xref: /petsc/src/ts/interface/ts.c (revision 6d187b9135d66ac23f29b4e7e5d4e626b6954b97)
1 
2 #include <petsc-private/tsimpl.h>        /*I "petscts.h"  I*/
3 #include <petscdmshell.h>
4 
5 /* Logging support */
6 PetscClassId  TS_CLASSID, DMTS_CLASSID;
7 PetscLogEvent  TS_Step, TS_PseudoComputeTimeStep, TS_FunctionEval, TS_JacobianEval;
8 
9 const char *const TSExactFinalTimeOptions[] = {"STEPOVER","INTERPOLATE","MATCHSTEP","TSExactFinalTimeOption","TS_EXACTFINALTIME_",0};
10 
11 #undef __FUNCT__
12 #define __FUNCT__ "TSSetTypeFromOptions"
13 /*
14   TSSetTypeFromOptions - Sets the type of ts from user options.
15 
16   Collective on TS
17 
18   Input Parameter:
19 . ts - The ts
20 
21   Level: intermediate
22 
23 .keywords: TS, set, options, database, type
24 .seealso: TSSetFromOptions(), TSSetType()
25 */
26 static PetscErrorCode TSSetTypeFromOptions(TS ts)
27 {
28   PetscBool      opt;
29   const char     *defaultType;
30   char           typeName[256];
31   PetscErrorCode ierr;
32 
33   PetscFunctionBegin;
34   if (((PetscObject)ts)->type_name) {
35     defaultType = ((PetscObject)ts)->type_name;
36   } else {
37     defaultType = TSEULER;
38   }
39 
40   if (!TSRegisterAllCalled) {ierr = TSRegisterAll(PETSC_NULL);CHKERRQ(ierr);}
41   ierr = PetscOptionsList("-ts_type", "TS method"," TSSetType", TSList, defaultType, typeName, 256, &opt);CHKERRQ(ierr);
42   if (opt) {
43     ierr = TSSetType(ts, typeName);CHKERRQ(ierr);
44   } else {
45     ierr = TSSetType(ts, defaultType);CHKERRQ(ierr);
46   }
47   PetscFunctionReturn(0);
48 }
49 
50 #undef __FUNCT__
51 #define __FUNCT__ "TSSetFromOptions"
52 /*@
53    TSSetFromOptions - Sets various TS parameters from user options.
54 
55    Collective on TS
56 
57    Input Parameter:
58 .  ts - the TS context obtained from TSCreate()
59 
60    Options Database Keys:
61 +  -ts_type <type> - TSEULER, TSBEULER, TSSUNDIALS, TSPSEUDO, TSCN, TSRK, TSTHETA, TSGL, TSSSP
62 .  -ts_max_steps maxsteps - maximum number of time-steps to take
63 .  -ts_final_time time - maximum time to compute to
64 .  -ts_dt dt - initial time step
65 .  -ts_monitor - print information at each timestep
66 .  -ts_monitor_lg_timestep - Monitor timestep size graphically
67 .  -ts_monitor_lg_solution - Monitor solution graphically
68 .  -ts_monitor_lg_error - Monitor error graphically
69 .  -ts_monitor_lg_snes_iterations - Monitor number nonlinear iterations for each timestep graphically
70 .  -ts_monitor_lg_ksp_iterations - Monitor number nonlinear iterations for each timestep graphically
71 .  -ts_monitor_sp_eig - Monitor eigenvalues of linearized operator graphically
72 .  -ts_monitor_draw_solution - Monitor solution graphically
73 .  -ts_monitor_draw_solution - Monitor solution graphically
74 .  -ts_monitor_draw_error - Monitor error graphically
75 .  -ts_monitor_draw_solution_binary <filename> - Save each solution to a binary file
76 -  -ts_monitor_draw_solution_vtk <filename.vts> - Save each time step to a binary file, use filename-%%03D.vts
77 
78    Level: beginner
79 
80 .keywords: TS, timestep, set, options, database
81 
82 .seealso: TSGetType()
83 @*/
84 PetscErrorCode  TSSetFromOptions(TS ts)
85 {
86   PetscBool      opt,flg;
87   PetscErrorCode ierr;
88   PetscViewer    monviewer;
89   char           monfilename[PETSC_MAX_PATH_LEN];
90   SNES           snes;
91   TSAdapt        adapt;
92   PetscReal      time_step;
93   TSExactFinalTimeOption      eftopt;
94 
95   PetscFunctionBegin;
96   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
97   ierr = PetscObjectOptionsBegin((PetscObject)ts);CHKERRQ(ierr);
98     /* Handle TS type options */
99     ierr = TSSetTypeFromOptions(ts);CHKERRQ(ierr);
100 
101     /* Handle generic TS options */
102     ierr = PetscOptionsInt("-ts_max_steps","Maximum number of time steps","TSSetDuration",ts->max_steps,&ts->max_steps,PETSC_NULL);CHKERRQ(ierr);
103     ierr = PetscOptionsReal("-ts_final_time","Time to run to","TSSetDuration",ts->max_time,&ts->max_time,PETSC_NULL);CHKERRQ(ierr);
104     ierr = PetscOptionsReal("-ts_init_time","Initial time","TSSetTime",ts->ptime,&ts->ptime,PETSC_NULL);CHKERRQ(ierr);
105     ierr = PetscOptionsReal("-ts_dt","Initial time step","TSSetTimeStep",ts->time_step,&time_step,&flg);CHKERRQ(ierr);
106     if (flg) {
107       ierr = TSSetTimeStep(ts,time_step);CHKERRQ(ierr);
108     }
109     ierr = PetscOptionsEnum("-ts_exact_final_time","Option for handling of final time step","TSSetExactFinalTime",TSExactFinalTimeOptions,(PetscEnum)ts->exact_final_time,(PetscEnum*)&eftopt,&flg);CHKERRQ(ierr);
110     if (flg) {ierr = TSSetExactFinalTime(ts,eftopt);CHKERRQ(ierr);}
111     ierr = PetscOptionsInt("-ts_max_snes_failures","Maximum number of nonlinear solve failures","TSSetMaxSNESFailures",ts->max_snes_failures,&ts->max_snes_failures,PETSC_NULL);CHKERRQ(ierr);
112     ierr = PetscOptionsInt("-ts_max_reject","Maximum number of step rejections before step fails","TSSetMaxStepRejections",ts->max_reject,&ts->max_reject,PETSC_NULL);CHKERRQ(ierr);
113     ierr = PetscOptionsBool("-ts_error_if_step_fails","Error if no step succeeds","TSSetErrorIfStepFails",ts->errorifstepfailed,&ts->errorifstepfailed,PETSC_NULL);CHKERRQ(ierr);
114     ierr = PetscOptionsReal("-ts_rtol","Relative tolerance for local truncation error","TSSetTolerances",ts->rtol,&ts->rtol,PETSC_NULL);CHKERRQ(ierr);
115     ierr = PetscOptionsReal("-ts_atol","Absolute tolerance for local truncation error","TSSetTolerances",ts->atol,&ts->atol,PETSC_NULL);CHKERRQ(ierr);
116 
117     /* Monitor options */
118     ierr = PetscOptionsString("-ts_monitor","Monitor timestep size","TSMonitorDefault","stdout",monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
119     if (flg) {
120       ierr = PetscViewerASCIIOpen(((PetscObject)ts)->comm,monfilename,&monviewer);CHKERRQ(ierr);
121       ierr = TSMonitorSet(ts,TSMonitorDefault,monviewer,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
122     }
123     ierr = PetscOptionsString("-ts_monitor_python","Use Python function","TSMonitorSet",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
124     if (flg) {ierr = PetscPythonMonitorSet((PetscObject)ts,monfilename);CHKERRQ(ierr);}
125 
126     ierr = PetscOptionsName("-ts_monitor_lg_timestep","Monitor timestep size graphically","TSMonitorLGTimeStep",&opt);CHKERRQ(ierr);
127     if (opt) {
128       TSMonitorLGCtx ctx;
129       PetscInt       howoften = 1;
130 
131       ierr = PetscOptionsInt("-ts_monitor_lg_timestep","Monitor timestep size graphically","TSMonitorLGTimeStep",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
132       ierr = TSMonitorLGCtxCreate(((PetscObject)ts)->comm,0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,howoften,&ctx);CHKERRQ(ierr);
133       ierr = TSMonitorSet(ts,TSMonitorLGTimeStep,ctx,(PetscErrorCode (*)(void**))TSMonitorLGCtxDestroy);CHKERRQ(ierr);
134     }
135     ierr = PetscOptionsName("-ts_monitor_lg_solution","Monitor solution graphically","TSMonitorLGSolution",&opt);CHKERRQ(ierr);
136     if (opt) {
137       TSMonitorLGCtx ctx;
138       PetscInt       howoften = 1;
139 
140       ierr = PetscOptionsInt("-ts_monitor_lg_solution","Monitor solution graphically","TSMonitorLGSolution",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
141       ierr = TSMonitorLGCtxCreate(PETSC_COMM_SELF,0,0,PETSC_DECIDE,PETSC_DECIDE,600,400,howoften,&ctx);
142       ierr = TSMonitorSet(ts,TSMonitorLGSolution,ctx,(PetscErrorCode (*)(void**))TSMonitorLGCtxDestroy);CHKERRQ(ierr);
143     }
144     ierr = PetscOptionsName("-ts_monitor_lg_error","Monitor error graphically","TSMonitorLGError",&opt);CHKERRQ(ierr);
145     if (opt) {
146       TSMonitorLGCtx ctx;
147       PetscInt       howoften = 1;
148 
149       ierr = PetscOptionsInt("-ts_monitor_lg_error","Monitor error graphically","TSMonitorLGError",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
150       ierr = TSMonitorLGCtxCreate(PETSC_COMM_SELF,0,0,PETSC_DECIDE,PETSC_DECIDE,600,400,howoften,&ctx);
151       ierr = TSMonitorSet(ts,TSMonitorLGError,ctx,(PetscErrorCode (*)(void**))TSMonitorLGCtxDestroy);CHKERRQ(ierr);
152     }
153     ierr = PetscOptionsName("-ts_monitor_lg_snes_iterations","Monitor number nonlinear iterations for each timestep graphically","TSMonitorLGSNESIterations",&opt);CHKERRQ(ierr);
154     if (opt) {
155       TSMonitorLGCtx ctx;
156       PetscInt       howoften = 1;
157 
158       ierr = PetscOptionsInt("-ts_monitor_lg_snes_iterations","Monitor number nonlinear iterations for each timestep graphically","TSMonitorLGSNESIterations",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
159       ierr = TSMonitorLGCtxCreate(PETSC_COMM_SELF,0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,howoften,&ctx);
160       ierr = TSMonitorSet(ts,TSMonitorLGSNESIterations,ctx,(PetscErrorCode (*)(void**))TSMonitorLGCtxDestroy);CHKERRQ(ierr);
161     }
162     ierr = PetscOptionsName("-ts_monitor_lg_ksp_iterations","Monitor number nonlinear iterations for each timestep graphically","TSMonitorLGKSPIterations",&opt);CHKERRQ(ierr);
163     if (opt) {
164       TSMonitorLGCtx ctx;
165       PetscInt       howoften = 1;
166 
167       ierr = PetscOptionsInt("-ts_monitor_lg_ksp_iterations","Monitor number nonlinear iterations for each timestep graphically","TSMonitorLGKSPIterations",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
168       ierr = TSMonitorLGCtxCreate(PETSC_COMM_SELF,0,0,PETSC_DECIDE,PETSC_DECIDE,300,300,howoften,&ctx);
169       ierr = TSMonitorSet(ts,TSMonitorLGKSPIterations,ctx,(PetscErrorCode (*)(void**))TSMonitorLGCtxDestroy);CHKERRQ(ierr);
170     }
171     ierr = PetscOptionsName("-ts_monitor_sp_eig","Monitor eigenvalues of linearized operator graphically","TSMonitorSPEig",&opt);CHKERRQ(ierr);
172     if (opt) {
173       TSMonitorSPEigCtx ctx;
174       PetscInt          howoften = 1;
175 
176       ierr = PetscOptionsInt("-ts_monitor_sp_eig","Monitor eigenvalues of linearized operator graphically","TSMonitorSPEig",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
177       ierr = TSMonitorSPEigCtxCreate(PETSC_COMM_SELF,0,0,PETSC_DECIDE,PETSC_DECIDE,600,400,howoften,&ctx);
178       ierr = TSMonitorSet(ts,TSMonitorSPEig,ctx,(PetscErrorCode (*)(void**))TSMonitorSPEigCtxDestroy);CHKERRQ(ierr);
179     }
180     opt  = PETSC_FALSE;
181     ierr = PetscOptionsName("-ts_monitor_draw_solution","Monitor solution graphically","TSMonitorDrawSolution",&opt);CHKERRQ(ierr);
182     if (opt) {
183       TSMonitorDrawCtx ctx;
184       PetscInt         howoften = 1;
185 
186       ierr = PetscOptionsInt("-ts_monitor_draw_solution","Monitor solution graphically","TSMonitorDrawSolution",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
187       ierr = TSMonitorDrawCtxCreate(((PetscObject)ts)->comm,0,0,PETSC_DECIDE,PETSC_DECIDE,600,400,howoften,&ctx);
188       ierr = TSMonitorSet(ts,TSMonitorDrawSolution,ctx,(PetscErrorCode (*)(void**))TSMonitorDrawCtxDestroy);CHKERRQ(ierr);
189     }
190     opt  = PETSC_FALSE;
191     ierr = PetscOptionsName("-ts_monitor_draw_error","Monitor error graphically","TSMonitorDrawError",&opt);CHKERRQ(ierr);
192     if (opt) {
193       TSMonitorDrawCtx ctx;
194       PetscInt         howoften = 1;
195 
196       ierr = PetscOptionsInt("-ts_monitor_draw_error","Monitor error graphically","TSMonitorDrawError",howoften,&howoften,PETSC_NULL);CHKERRQ(ierr);
197       ierr = TSMonitorDrawCtxCreate(((PetscObject)ts)->comm,0,0,PETSC_DECIDE,PETSC_DECIDE,600,400,howoften,&ctx);
198       ierr = TSMonitorSet(ts,TSMonitorDrawError,ctx,(PetscErrorCode (*)(void**))TSMonitorDrawCtxDestroy);CHKERRQ(ierr);
199     }
200     opt  = PETSC_FALSE;
201     ierr = PetscOptionsString("-ts_monitor_draw_solution_binary","Save each solution to a binary file","TSMonitorSolutionBinary",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
202     if (flg) {
203       PetscViewer ctx;
204       if (monfilename[0]) {
205         ierr = PetscViewerBinaryOpen(((PetscObject)ts)->comm,monfilename,FILE_MODE_WRITE,&ctx);CHKERRQ(ierr);
206       } else {
207         ctx = PETSC_VIEWER_BINARY_(((PetscObject)ts)->comm);
208       }
209       ierr = TSMonitorSet(ts,TSMonitorSolutionBinary,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);CHKERRQ(ierr);
210     }
211     opt  = PETSC_FALSE;
212     ierr = PetscOptionsString("-ts_monitor_draw_solution_vtk","Save each time step to a binary file, use filename-%%03D.vts","TSMonitorSolutionVTK",0,monfilename,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
213     if (flg) {
214       const char *ptr,*ptr2;
215       char *filetemplate;
216       if (!monfilename[0]) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"-ts_monitor_draw_solution_vtk requires a file template, e.g. filename-%%03D.vts");
217       /* Do some cursory validation of the input. */
218       ierr = PetscStrstr(monfilename,"%",(char**)&ptr);CHKERRQ(ierr);
219       if (!ptr) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"-ts_monitor_draw_solution_vtk requires a file template, e.g. filename-%%03D.vts");
220       for (ptr++ ; ptr && *ptr; ptr++) {
221         ierr = PetscStrchr("DdiouxX",*ptr,(char**)&ptr2);CHKERRQ(ierr);
222         if (!ptr2 && (*ptr < '0' || '9' < *ptr)) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"Invalid file template argument to -ts_monitor_draw_solution_vtk, should look like filename-%%03D.vts");
223         if (ptr2) break;
224       }
225       ierr = PetscStrallocpy(monfilename,&filetemplate);CHKERRQ(ierr);
226       ierr = TSMonitorSet(ts,TSMonitorSolutionVTK,filetemplate,(PetscErrorCode (*)(void**))TSMonitorSolutionVTKDestroy);CHKERRQ(ierr);
227     }
228 
229     ierr = TSGetTSAdapt(ts,&adapt);CHKERRQ(ierr);
230     ierr = TSAdaptSetFromOptions(adapt);CHKERRQ(ierr);
231 
232     ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
233     if (ts->problem_type == TS_LINEAR) {ierr = SNESSetType(snes,SNESKSPONLY);CHKERRQ(ierr);}
234 
235     /* Handle specific TS options */
236     if (ts->ops->setfromoptions) {
237       ierr = (*ts->ops->setfromoptions)(ts);CHKERRQ(ierr);
238     }
239 
240     /* process any options handlers added with PetscObjectAddOptionsHandler() */
241     ierr = PetscObjectProcessOptionsHandlers((PetscObject)ts);CHKERRQ(ierr);
242   ierr = PetscOptionsEnd();CHKERRQ(ierr);
243   PetscFunctionReturn(0);
244 }
245 
246 #undef __FUNCT__
247 #undef __FUNCT__
248 #define __FUNCT__ "TSComputeRHSJacobian"
249 /*@
250    TSComputeRHSJacobian - Computes the Jacobian matrix that has been
251       set with TSSetRHSJacobian().
252 
253    Collective on TS and Vec
254 
255    Input Parameters:
256 +  ts - the TS context
257 .  t - current timestep
258 -  U - input vector
259 
260    Output Parameters:
261 +  A - Jacobian matrix
262 .  B - optional preconditioning matrix
263 -  flag - flag indicating matrix structure
264 
265    Notes:
266    Most users should not need to explicitly call this routine, as it
267    is used internally within the nonlinear solvers.
268 
269    See KSPSetOperators() for important information about setting the
270    flag parameter.
271 
272    Level: developer
273 
274 .keywords: SNES, compute, Jacobian, matrix
275 
276 .seealso:  TSSetRHSJacobian(), KSPSetOperators()
277 @*/
278 PetscErrorCode  TSComputeRHSJacobian(TS ts,PetscReal t,Vec U,Mat *A,Mat *B,MatStructure *flg)
279 {
280   PetscErrorCode ierr;
281   PetscInt       Ustate;
282   DM             dm;
283   DMTS           tsdm;
284   TSRHSJacobian  rhsjacobianfunc;
285   void           *ctx;
286   TSIJacobian    ijacobianfunc;
287 
288   PetscFunctionBegin;
289   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
290   PetscValidHeaderSpecific(U,VEC_CLASSID,3);
291   PetscCheckSameComm(ts,1,U,3);
292   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
293   ierr = DMGetDMTS(dm,&tsdm);CHKERRQ(ierr);
294   ierr = DMTSGetRHSJacobian(dm,&rhsjacobianfunc,&ctx);CHKERRQ(ierr);
295   ierr = DMTSGetIJacobian(dm,&ijacobianfunc,PETSC_NULL);CHKERRQ(ierr);
296   ierr = PetscObjectStateQuery((PetscObject)U,&Ustate);CHKERRQ(ierr);
297   if (ts->rhsjacobian.time == t && (ts->problem_type == TS_LINEAR || (ts->rhsjacobian.X == U && ts->rhsjacobian.Xstate == Ustate))) {
298     *flg = ts->rhsjacobian.mstructure;
299     PetscFunctionReturn(0);
300   }
301 
302   if (!rhsjacobianfunc && !ijacobianfunc) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"Must call TSSetRHSJacobian() and / or TSSetIJacobian()");
303 
304   if (rhsjacobianfunc) {
305     ierr = PetscLogEventBegin(TS_JacobianEval,ts,U,*A,*B);CHKERRQ(ierr);
306     *flg = DIFFERENT_NONZERO_PATTERN;
307     PetscStackPush("TS user Jacobian function");
308     ierr = (*rhsjacobianfunc)(ts,t,U,A,B,flg,ctx);CHKERRQ(ierr);
309     PetscStackPop;
310     ierr = PetscLogEventEnd(TS_JacobianEval,ts,U,*A,*B);CHKERRQ(ierr);
311     /* make sure user returned a correct Jacobian and preconditioner */
312     PetscValidHeaderSpecific(*A,MAT_CLASSID,4);
313     PetscValidHeaderSpecific(*B,MAT_CLASSID,5);
314   } else {
315     ierr = MatZeroEntries(*A);CHKERRQ(ierr);
316     if (*A != *B) {ierr = MatZeroEntries(*B);CHKERRQ(ierr);}
317     *flg = SAME_NONZERO_PATTERN;
318   }
319   ts->rhsjacobian.time = t;
320   ts->rhsjacobian.X = U;
321   ierr = PetscObjectStateQuery((PetscObject)U,&ts->rhsjacobian.Xstate);CHKERRQ(ierr);
322   ts->rhsjacobian.mstructure = *flg;
323   PetscFunctionReturn(0);
324 }
325 
326 #undef __FUNCT__
327 #define __FUNCT__ "TSComputeRHSFunction"
328 /*@
329    TSComputeRHSFunction - Evaluates the right-hand-side function.
330 
331    Collective on TS and Vec
332 
333    Input Parameters:
334 +  ts - the TS context
335 .  t - current time
336 -  U - state vector
337 
338    Output Parameter:
339 .  y - right hand side
340 
341    Note:
342    Most users should not need to explicitly call this routine, as it
343    is used internally within the nonlinear solvers.
344 
345    Level: developer
346 
347 .keywords: TS, compute
348 
349 .seealso: TSSetRHSFunction(), TSComputeIFunction()
350 @*/
351 PetscErrorCode TSComputeRHSFunction(TS ts,PetscReal t,Vec U,Vec y)
352 {
353   PetscErrorCode ierr;
354   TSRHSFunction  rhsfunction;
355   TSIFunction    ifunction;
356   void           *ctx;
357   DM             dm;
358 
359   PetscFunctionBegin;
360   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
361   PetscValidHeaderSpecific(U,VEC_CLASSID,3);
362   PetscValidHeaderSpecific(y,VEC_CLASSID,4);
363   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
364   ierr = DMTSGetRHSFunction(dm,&rhsfunction,&ctx);CHKERRQ(ierr);
365   ierr = DMTSGetIFunction(dm,&ifunction,PETSC_NULL);CHKERRQ(ierr);
366 
367   if (!rhsfunction && !ifunction) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"Must call TSSetRHSFunction() and / or TSSetIFunction()");
368 
369   ierr = PetscLogEventBegin(TS_FunctionEval,ts,U,y,0);CHKERRQ(ierr);
370   if (rhsfunction) {
371     PetscStackPush("TS user right-hand-side function");
372     ierr = (*rhsfunction)(ts,t,U,y,ctx);CHKERRQ(ierr);
373     PetscStackPop;
374   } else {
375     ierr = VecZeroEntries(y);CHKERRQ(ierr);
376   }
377 
378   ierr = PetscLogEventEnd(TS_FunctionEval,ts,U,y,0);CHKERRQ(ierr);
379   PetscFunctionReturn(0);
380 }
381 
382 #undef __FUNCT__
383 #define __FUNCT__ "TSComputeSolutionFunction"
384 /*@
385    TSComputeSolutionFunction - Evaluates the solution function.
386 
387    Collective on TS and Vec
388 
389    Input Parameters:
390 +  ts - the TS context
391 -  t - current time
392 
393    Output Parameter:
394 .  U - the solution
395 
396    Note:
397    Most users should not need to explicitly call this routine, as it
398    is used internally within the nonlinear solvers.
399 
400    Level: developer
401 
402 .keywords: TS, compute
403 
404 .seealso: TSSetSolutionFunction(), TSSetRHSFunction(), TSComputeIFunction()
405 @*/
406 PetscErrorCode TSComputeSolutionFunction(TS ts,PetscReal t,Vec U)
407 {
408   PetscErrorCode     ierr;
409   TSSolutionFunction solutionfunction;
410   void               *ctx;
411   DM                 dm;
412 
413   PetscFunctionBegin;
414   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
415   PetscValidHeaderSpecific(U,VEC_CLASSID,3);
416   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
417   ierr = DMTSGetSolutionFunction(dm,&solutionfunction,&ctx);CHKERRQ(ierr);
418 
419   if (solutionfunction) {
420     PetscStackPush("TS user right-hand-side function");
421     ierr = (*solutionfunction)(ts,t,U,ctx);CHKERRQ(ierr);
422     PetscStackPop;
423   }
424   PetscFunctionReturn(0);
425 }
426 
427 #undef __FUNCT__
428 #define __FUNCT__ "TSGetRHSVec_Private"
429 static PetscErrorCode TSGetRHSVec_Private(TS ts,Vec *Frhs)
430 {
431   Vec            F;
432   PetscErrorCode ierr;
433 
434   PetscFunctionBegin;
435   *Frhs = PETSC_NULL;
436   ierr = TSGetIFunction(ts,&F,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
437   if (!ts->Frhs) {
438     ierr = VecDuplicate(F,&ts->Frhs);CHKERRQ(ierr);
439   }
440   *Frhs = ts->Frhs;
441   PetscFunctionReturn(0);
442 }
443 
444 #undef __FUNCT__
445 #define __FUNCT__ "TSGetRHSMats_Private"
446 static PetscErrorCode TSGetRHSMats_Private(TS ts,Mat *Arhs,Mat *Brhs)
447 {
448   Mat            A,B;
449   PetscErrorCode ierr;
450 
451   PetscFunctionBegin;
452   ierr = TSGetIJacobian(ts,&A,&B,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
453   if (Arhs) {
454     if (!ts->Arhs) {
455       ierr = MatDuplicate(A,MAT_DO_NOT_COPY_VALUES,&ts->Arhs);CHKERRQ(ierr);
456     }
457     *Arhs = ts->Arhs;
458   }
459   if (Brhs) {
460     if (!ts->Brhs) {
461       ierr = MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&ts->Brhs);CHKERRQ(ierr);
462     }
463     *Brhs = ts->Brhs;
464   }
465   PetscFunctionReturn(0);
466 }
467 
468 #undef __FUNCT__
469 #define __FUNCT__ "TSComputeIFunction"
470 /*@
471    TSComputeIFunction - Evaluates the DAE residual written in implicit form F(t,U,Udot)=0
472 
473    Collective on TS and Vec
474 
475    Input Parameters:
476 +  ts - the TS context
477 .  t - current time
478 .  U - state vector
479 .  Udot - time derivative of state vector
480 -  imex - flag indicates if the method is IMEX so that the RHSFunction should be kept separate
481 
482    Output Parameter:
483 .  Y - right hand side
484 
485    Note:
486    Most users should not need to explicitly call this routine, as it
487    is used internally within the nonlinear solvers.
488 
489    If the user did did not write their equations in implicit form, this
490    function recasts them in implicit form.
491 
492    Level: developer
493 
494 .keywords: TS, compute
495 
496 .seealso: TSSetIFunction(), TSComputeRHSFunction()
497 @*/
498 PetscErrorCode TSComputeIFunction(TS ts,PetscReal t,Vec U,Vec Udot,Vec Y,PetscBool imex)
499 {
500   PetscErrorCode ierr;
501   TSIFunction    ifunction;
502   TSRHSFunction  rhsfunction;
503   void           *ctx;
504   DM             dm;
505 
506   PetscFunctionBegin;
507   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
508   PetscValidHeaderSpecific(U,VEC_CLASSID,3);
509   PetscValidHeaderSpecific(Udot,VEC_CLASSID,4);
510   PetscValidHeaderSpecific(Y,VEC_CLASSID,5);
511 
512   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
513   ierr = DMTSGetIFunction(dm,&ifunction,&ctx);CHKERRQ(ierr);
514   ierr = DMTSGetRHSFunction(dm,&rhsfunction,PETSC_NULL);CHKERRQ(ierr);
515 
516   if (!rhsfunction && !ifunction) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"Must call TSSetRHSFunction() and / or TSSetIFunction()");
517 
518   ierr = PetscLogEventBegin(TS_FunctionEval,ts,U,Udot,Y);CHKERRQ(ierr);
519   if (ifunction) {
520     PetscStackPush("TS user implicit function");
521     ierr = (*ifunction)(ts,t,U,Udot,Y,ctx);CHKERRQ(ierr);
522     PetscStackPop;
523   }
524   if (imex) {
525     if (!ifunction) {
526       ierr = VecCopy(Udot,Y);CHKERRQ(ierr);
527     }
528   } else if (rhsfunction) {
529     if (ifunction) {
530       Vec Frhs;
531       ierr = TSGetRHSVec_Private(ts,&Frhs);CHKERRQ(ierr);
532       ierr = TSComputeRHSFunction(ts,t,U,Frhs);CHKERRQ(ierr);
533       ierr = VecAXPY(Y,-1,Frhs);CHKERRQ(ierr);
534     } else {
535       ierr = TSComputeRHSFunction(ts,t,U,Y);CHKERRQ(ierr);
536       ierr = VecAYPX(Y,-1,Udot);CHKERRQ(ierr);
537     }
538   }
539   ierr = PetscLogEventEnd(TS_FunctionEval,ts,U,Udot,Y);CHKERRQ(ierr);
540   PetscFunctionReturn(0);
541 }
542 
543 #undef __FUNCT__
544 #define __FUNCT__ "TSComputeIJacobian"
545 /*@
546    TSComputeIJacobian - Evaluates the Jacobian of the DAE
547 
548    Collective on TS and Vec
549 
550    Input
551       Input Parameters:
552 +  ts - the TS context
553 .  t - current timestep
554 .  U - state vector
555 .  Udot - time derivative of state vector
556 .  shift - shift to apply, see note below
557 -  imex - flag indicates if the method is IMEX so that the RHSJacobian should be kept separate
558 
559    Output Parameters:
560 +  A - Jacobian matrix
561 .  B - optional preconditioning matrix
562 -  flag - flag indicating matrix structure
563 
564    Notes:
565    If F(t,U,Udot)=0 is the DAE, the required Jacobian is
566 
567    dF/dU + shift*dF/dUdot
568 
569    Most users should not need to explicitly call this routine, as it
570    is used internally within the nonlinear solvers.
571 
572    Level: developer
573 
574 .keywords: TS, compute, Jacobian, matrix
575 
576 .seealso:  TSSetIJacobian()
577 @*/
578 PetscErrorCode TSComputeIJacobian(TS ts,PetscReal t,Vec U,Vec Udot,PetscReal shift,Mat *A,Mat *B,MatStructure *flg,PetscBool imex)
579 {
580   PetscInt       Ustate, Udotstate;
581   PetscErrorCode ierr;
582   TSIJacobian    ijacobian;
583   TSRHSJacobian  rhsjacobian;
584   DM             dm;
585   void           *ctx;
586 
587   PetscFunctionBegin;
588 
589   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
590   PetscValidHeaderSpecific(U,VEC_CLASSID,3);
591   PetscValidHeaderSpecific(Udot,VEC_CLASSID,4);
592   PetscValidPointer(A,6);
593   PetscValidHeaderSpecific(*A,MAT_CLASSID,6);
594   PetscValidPointer(B,7);
595   PetscValidHeaderSpecific(*B,MAT_CLASSID,7);
596   PetscValidPointer(flg,8);
597 
598   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
599   ierr = DMTSGetIJacobian(dm,&ijacobian,&ctx);CHKERRQ(ierr);
600   ierr = DMTSGetRHSJacobian(dm,&rhsjacobian,PETSC_NULL);CHKERRQ(ierr);
601 
602   ierr = PetscObjectStateQuery((PetscObject)U,&Ustate);CHKERRQ(ierr);
603   ierr = PetscObjectStateQuery((PetscObject)Udot,&Udotstate);CHKERRQ(ierr);
604   if (ts->ijacobian.time == t && (ts->problem_type == TS_LINEAR || (ts->ijacobian.X == U && ts->ijacobian.Xstate == Ustate && ts->ijacobian.Xdot == Udot && ts->ijacobian.Xdotstate == Udotstate && ts->ijacobian.imex == imex))) {
605     *flg = ts->ijacobian.mstructure;
606     ierr = MatScale(*A, shift / ts->ijacobian.shift);CHKERRQ(ierr);
607     PetscFunctionReturn(0);
608   }
609 
610   if (!rhsjacobian && !ijacobian) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_USER,"Must call TSSetRHSJacobian() and / or TSSetIJacobian()");
611 
612   *flg = SAME_NONZERO_PATTERN;  /* In case we're solving a linear problem in which case it wouldn't get initialized below. */
613   ierr = PetscLogEventBegin(TS_JacobianEval,ts,U,*A,*B);CHKERRQ(ierr);
614   if (ijacobian) {
615     *flg = DIFFERENT_NONZERO_PATTERN;
616     PetscStackPush("TS user implicit Jacobian");
617     ierr = (*ijacobian)(ts,t,U,Udot,shift,A,B,flg,ctx);CHKERRQ(ierr);
618     PetscStackPop;
619     /* make sure user returned a correct Jacobian and preconditioner */
620     PetscValidHeaderSpecific(*A,MAT_CLASSID,4);
621     PetscValidHeaderSpecific(*B,MAT_CLASSID,5);
622   }
623   if (imex) {
624     if (!ijacobian) {  /* system was written as Udot = G(t,U) */
625       ierr = MatZeroEntries(*A);CHKERRQ(ierr);
626       ierr = MatShift(*A,shift);CHKERRQ(ierr);
627       if (*A != *B) {
628         ierr = MatZeroEntries(*B);CHKERRQ(ierr);
629         ierr = MatShift(*B,shift);CHKERRQ(ierr);
630       }
631       *flg = SAME_PRECONDITIONER;
632     }
633   } else {
634     if (!ijacobian) {
635       ierr = TSComputeRHSJacobian(ts,t,U,A,B,flg);CHKERRQ(ierr);
636       ierr = MatScale(*A,-1);CHKERRQ(ierr);
637       ierr = MatShift(*A,shift);CHKERRQ(ierr);
638       if (*A != *B) {
639         ierr = MatScale(*B,-1);CHKERRQ(ierr);
640         ierr = MatShift(*B,shift);CHKERRQ(ierr);
641       }
642     } else if (rhsjacobian) {
643       Mat Arhs,Brhs;
644       MatStructure axpy,flg2 = DIFFERENT_NONZERO_PATTERN;
645       ierr = TSGetRHSMats_Private(ts,&Arhs,&Brhs);CHKERRQ(ierr);
646       ierr = TSComputeRHSJacobian(ts,t,U,&Arhs,&Brhs,&flg2);CHKERRQ(ierr);
647       axpy = (*flg == flg2) ? SAME_NONZERO_PATTERN : DIFFERENT_NONZERO_PATTERN;
648       ierr = MatAXPY(*A,-1,Arhs,axpy);CHKERRQ(ierr);
649       if (*A != *B) {
650         ierr = MatAXPY(*B,-1,Brhs,axpy);CHKERRQ(ierr);
651       }
652       *flg = PetscMin(*flg,flg2);
653     }
654   }
655 
656   ts->ijacobian.time = t;
657   ts->ijacobian.X = U;
658   ts->ijacobian.Xdot = Udot;
659   ierr = PetscObjectStateQuery((PetscObject)U,&ts->ijacobian.Xstate);CHKERRQ(ierr);
660   ierr = PetscObjectStateQuery((PetscObject)Udot,&ts->ijacobian.Xdotstate);CHKERRQ(ierr);
661   ts->ijacobian.shift = shift;
662   ts->ijacobian.imex = imex;
663   ts->ijacobian.mstructure = *flg;
664   ierr = PetscLogEventEnd(TS_JacobianEval,ts,U,*A,*B);CHKERRQ(ierr);
665   PetscFunctionReturn(0);
666 }
667 
668 #undef __FUNCT__
669 #define __FUNCT__ "TSSetRHSFunction"
670 /*@C
671     TSSetRHSFunction - Sets the routine for evaluating the function,
672     where U_t = G(t,u).
673 
674     Logically Collective on TS
675 
676     Input Parameters:
677 +   ts - the TS context obtained from TSCreate()
678 .   r - vector to put the computed right hand side (or PETSC_NULL to have it created)
679 .   f - routine for evaluating the right-hand-side function
680 -   ctx - [optional] user-defined context for private data for the
681           function evaluation routine (may be PETSC_NULL)
682 
683     Calling sequence of func:
684 $     func (TS ts,PetscReal t,Vec u,Vec F,void *ctx);
685 
686 +   t - current timestep
687 .   u - input vector
688 .   F - function vector
689 -   ctx - [optional] user-defined function context
690 
691     Level: beginner
692 
693 .keywords: TS, timestep, set, right-hand-side, function
694 
695 .seealso: TSSetRHSJacobian(), TSSetIJacobian()
696 @*/
697 PetscErrorCode  TSSetRHSFunction(TS ts,Vec r,PetscErrorCode (*f)(TS,PetscReal,Vec,Vec,void*),void *ctx)
698 {
699   PetscErrorCode ierr;
700   SNES           snes;
701   Vec            ralloc = PETSC_NULL;
702   DM             dm;
703 
704   PetscFunctionBegin;
705   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
706   if (r) PetscValidHeaderSpecific(r,VEC_CLASSID,2);
707 
708   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
709   ierr = DMTSSetRHSFunction(dm,f,ctx);CHKERRQ(ierr);
710   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
711   if (!r && !ts->dm && ts->vec_sol) {
712     ierr = VecDuplicate(ts->vec_sol,&ralloc);CHKERRQ(ierr);
713     r = ralloc;
714   }
715   ierr = SNESSetFunction(snes,r,SNESTSFormFunction,ts);CHKERRQ(ierr);
716   ierr = VecDestroy(&ralloc);CHKERRQ(ierr);
717   PetscFunctionReturn(0);
718 }
719 
720 #undef __FUNCT__
721 #define __FUNCT__ "TSSetSolutionFunction"
722 /*@C
723     TSSetSolutionFunction - Provide a function that computes the solution of the ODE or DAE
724 
725     Logically Collective on TS
726 
727     Input Parameters:
728 +   ts - the TS context obtained from TSCreate()
729 .   f - routine for evaluating the solution
730 -   ctx - [optional] user-defined context for private data for the
731           function evaluation routine (may be PETSC_NULL)
732 
733     Calling sequence of func:
734 $     func (TS ts,PetscReal t,Vec u,void *ctx);
735 
736 +   t - current timestep
737 .   u - output vector
738 -   ctx - [optional] user-defined function context
739 
740     Notes:
741     This routine is used for testing accuracy of time integration schemes when you already know the solution.
742     If analytic solutions are not known for your system, consider using the Method of Manufactured Solutions to
743     create closed-form solutions with non-physical forcing terms.
744 
745     For low-dimensional problems solved in serial, such as small discrete systems, TSMonitorLGError() can be used to monitor the error history.
746 
747     Level: beginner
748 
749 .keywords: TS, timestep, set, right-hand-side, function
750 
751 .seealso: TSSetRHSJacobian(), TSSetIJacobian(), TSComputeSolutionFunction()
752 @*/
753 PetscErrorCode  TSSetSolutionFunction(TS ts,PetscErrorCode (*f)(TS,PetscReal,Vec,void*),void *ctx)
754 {
755   PetscErrorCode ierr;
756   DM             dm;
757 
758   PetscFunctionBegin;
759   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
760   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
761   ierr = DMTSSetSolutionFunction(dm,f,ctx);CHKERRQ(ierr);
762   PetscFunctionReturn(0);
763 }
764 
765 #undef __FUNCT__
766 #define __FUNCT__ "TSSetRHSJacobian"
767 /*@C
768    TSSetRHSJacobian - Sets the function to compute the Jacobian of F,
769    where U_t = G(U,t), as well as the location to store the matrix.
770 
771    Logically Collective on TS
772 
773    Input Parameters:
774 +  ts  - the TS context obtained from TSCreate()
775 .  A   - Jacobian matrix
776 .  B   - preconditioner matrix (usually same as A)
777 .  f   - the Jacobian evaluation routine
778 -  ctx - [optional] user-defined context for private data for the
779          Jacobian evaluation routine (may be PETSC_NULL)
780 
781    Calling sequence of func:
782 $     func (TS ts,PetscReal t,Vec u,Mat *A,Mat *B,MatStructure *flag,void *ctx);
783 
784 +  t - current timestep
785 .  u - input vector
786 .  A - matrix A, where U_t = A(t)u
787 .  B - preconditioner matrix, usually the same as A
788 .  flag - flag indicating information about the preconditioner matrix
789           structure (same as flag in KSPSetOperators())
790 -  ctx - [optional] user-defined context for matrix evaluation routine
791 
792    Notes:
793    See KSPSetOperators() for important information about setting the flag
794    output parameter in the routine func().  Be sure to read this information!
795 
796    The routine func() takes Mat * as the matrix arguments rather than Mat.
797    This allows the matrix evaluation routine to replace A and/or B with a
798    completely new matrix structure (not just different matrix elements)
799    when appropriate, for instance, if the nonzero structure is changing
800    throughout the global iterations.
801 
802    Level: beginner
803 
804 .keywords: TS, timestep, set, right-hand-side, Jacobian
805 
806 .seealso: SNESDefaultComputeJacobianColor(), TSSetRHSFunction()
807 
808 @*/
809 PetscErrorCode  TSSetRHSJacobian(TS ts,Mat A,Mat B,TSRHSJacobian f,void *ctx)
810 {
811   PetscErrorCode ierr;
812   SNES           snes;
813   DM             dm;
814   TSIJacobian    ijacobian;
815 
816   PetscFunctionBegin;
817   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
818   if (A) PetscValidHeaderSpecific(A,MAT_CLASSID,2);
819   if (B) PetscValidHeaderSpecific(B,MAT_CLASSID,3);
820   if (A) PetscCheckSameComm(ts,1,A,2);
821   if (B) PetscCheckSameComm(ts,1,B,3);
822 
823   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
824   ierr = DMTSSetRHSJacobian(dm,f,ctx);CHKERRQ(ierr);
825   ierr = DMTSGetIJacobian(dm,&ijacobian,PETSC_NULL);CHKERRQ(ierr);
826 
827   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
828   if (!ijacobian) {
829     ierr = SNESSetJacobian(snes,A,B,SNESTSFormJacobian,ts);CHKERRQ(ierr);
830   }
831   if (A) {
832     ierr = PetscObjectReference((PetscObject)A);CHKERRQ(ierr);
833     ierr = MatDestroy(&ts->Arhs);CHKERRQ(ierr);
834     ts->Arhs = A;
835   }
836   if (B) {
837     ierr = PetscObjectReference((PetscObject)B);CHKERRQ(ierr);
838     ierr = MatDestroy(&ts->Brhs);CHKERRQ(ierr);
839     ts->Brhs = B;
840   }
841   PetscFunctionReturn(0);
842 }
843 
844 
845 #undef __FUNCT__
846 #define __FUNCT__ "TSSetIFunction"
847 /*@C
848    TSSetIFunction - Set the function to compute F(t,U,U_t) where F() = 0 is the DAE to be solved.
849 
850    Logically Collective on TS
851 
852    Input Parameters:
853 +  ts  - the TS context obtained from TSCreate()
854 .  r   - vector to hold the residual (or PETSC_NULL to have it created internally)
855 .  f   - the function evaluation routine
856 -  ctx - user-defined context for private data for the function evaluation routine (may be PETSC_NULL)
857 
858    Calling sequence of f:
859 $  f(TS ts,PetscReal t,Vec u,Vec u_t,Vec F,ctx);
860 
861 +  t   - time at step/stage being solved
862 .  u   - state vector
863 .  u_t - time derivative of state vector
864 .  F   - function vector
865 -  ctx - [optional] user-defined context for matrix evaluation routine
866 
867    Important:
868    The user MUST call either this routine, TSSetRHSFunction().  This routine must be used when not solving an ODE, for example a DAE.
869 
870    Level: beginner
871 
872 .keywords: TS, timestep, set, DAE, Jacobian
873 
874 .seealso: TSSetRHSJacobian(), TSSetRHSFunction(), TSSetIJacobian()
875 @*/
876 PetscErrorCode  TSSetIFunction(TS ts,Vec res,TSIFunction f,void *ctx)
877 {
878   PetscErrorCode ierr;
879   SNES           snes;
880   Vec            resalloc = PETSC_NULL;
881   DM             dm;
882 
883   PetscFunctionBegin;
884   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
885   if (res) PetscValidHeaderSpecific(res,VEC_CLASSID,2);
886 
887   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
888   ierr = DMTSSetIFunction(dm,f,ctx);CHKERRQ(ierr);
889 
890   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
891   if (!res && !ts->dm && ts->vec_sol) {
892     ierr = VecDuplicate(ts->vec_sol,&resalloc);CHKERRQ(ierr);
893     res = resalloc;
894   }
895   ierr = SNESSetFunction(snes,res,SNESTSFormFunction,ts);CHKERRQ(ierr);
896   ierr = VecDestroy(&resalloc);CHKERRQ(ierr);
897 
898   PetscFunctionReturn(0);
899 }
900 
901 #undef __FUNCT__
902 #define __FUNCT__ "TSGetIFunction"
903 /*@C
904    TSGetIFunction - Returns the vector where the implicit residual is stored and the function/contex to compute it.
905 
906    Not Collective
907 
908    Input Parameter:
909 .  ts - the TS context
910 
911    Output Parameter:
912 +  r - vector to hold residual (or PETSC_NULL)
913 .  func - the function to compute residual (or PETSC_NULL)
914 -  ctx - the function context (or PETSC_NULL)
915 
916    Level: advanced
917 
918 .keywords: TS, nonlinear, get, function
919 
920 .seealso: TSSetIFunction(), SNESGetFunction()
921 @*/
922 PetscErrorCode TSGetIFunction(TS ts,Vec *r,TSIFunction *func,void **ctx)
923 {
924   PetscErrorCode ierr;
925   SNES           snes;
926   DM             dm;
927 
928   PetscFunctionBegin;
929   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
930   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
931   ierr = SNESGetFunction(snes,r,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
932   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
933   ierr = DMTSGetIFunction(dm,func,ctx);CHKERRQ(ierr);
934   PetscFunctionReturn(0);
935 }
936 
937 #undef __FUNCT__
938 #define __FUNCT__ "TSGetRHSFunction"
939 /*@C
940    TSGetRHSFunction - Returns the vector where the right hand side is stored and the function/context to compute it.
941 
942    Not Collective
943 
944    Input Parameter:
945 .  ts - the TS context
946 
947    Output Parameter:
948 +  r - vector to hold computed right hand side (or PETSC_NULL)
949 .  func - the function to compute right hand side (or PETSC_NULL)
950 -  ctx - the function context (or PETSC_NULL)
951 
952    Level: advanced
953 
954 .keywords: TS, nonlinear, get, function
955 
956 .seealso: TSSetRhsfunction(), SNESGetFunction()
957 @*/
958 PetscErrorCode TSGetRHSFunction(TS ts,Vec *r,TSRHSFunction *func,void **ctx)
959 {
960   PetscErrorCode ierr;
961   SNES           snes;
962   DM             dm;
963 
964   PetscFunctionBegin;
965   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
966   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
967   ierr = SNESGetFunction(snes,r,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
968   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
969   ierr = DMTSGetRHSFunction(dm,func,ctx);CHKERRQ(ierr);
970   PetscFunctionReturn(0);
971 }
972 
973 #undef __FUNCT__
974 #define __FUNCT__ "TSSetIJacobian"
975 /*@C
976    TSSetIJacobian - Set the function to compute the matrix dF/dU + a*dF/dU_t where F(t,U,U_t) is the function
977         you provided with TSSetIFunction().
978 
979    Logically Collective on TS
980 
981    Input Parameters:
982 +  ts  - the TS context obtained from TSCreate()
983 .  A   - Jacobian matrix
984 .  B   - preconditioning matrix for A (may be same as A)
985 .  f   - the Jacobian evaluation routine
986 -  ctx - user-defined context for private data for the Jacobian evaluation routine (may be PETSC_NULL)
987 
988    Calling sequence of f:
989 $  f(TS ts,PetscReal t,Vec U,Vec U_t,PetscReal a,Mat *A,Mat *B,MatStructure *flag,void *ctx);
990 
991 +  t    - time at step/stage being solved
992 .  U    - state vector
993 .  U_t  - time derivative of state vector
994 .  a    - shift
995 .  A    - Jacobian of F(t,U,W+a*U), equivalent to dF/dU + a*dF/dU_t
996 .  B    - preconditioning matrix for A, may be same as A
997 .  flag - flag indicating information about the preconditioner matrix
998           structure (same as flag in KSPSetOperators())
999 -  ctx  - [optional] user-defined context for matrix evaluation routine
1000 
1001    Notes:
1002    The matrices A and B are exactly the matrices that are used by SNES for the nonlinear solve.
1003 
1004    The matrix dF/dU + a*dF/dU_t you provide turns out to be
1005    the Jacobian of F(t,U,W+a*U) where F(t,U,U_t) = 0 is the DAE to be solved.
1006    The time integrator internally approximates U_t by W+a*U where the positive "shift"
1007    a and vector W depend on the integration method, step size, and past states. For example with
1008    the backward Euler method a = 1/dt and W = -a*U(previous timestep) so
1009    W + a*U = a*(U - U(previous timestep)) = (U - U(previous timestep))/dt
1010 
1011    Level: beginner
1012 
1013 .keywords: TS, timestep, DAE, Jacobian
1014 
1015 .seealso: TSSetIFunction(), TSSetRHSJacobian(), SNESDefaultComputeJacobianColor(), SNESDefaultComputeJacobian()
1016 
1017 @*/
1018 PetscErrorCode  TSSetIJacobian(TS ts,Mat A,Mat B,TSIJacobian f,void *ctx)
1019 {
1020   PetscErrorCode ierr;
1021   SNES           snes;
1022   DM             dm;
1023 
1024   PetscFunctionBegin;
1025   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1026   if (A) PetscValidHeaderSpecific(A,MAT_CLASSID,2);
1027   if (B) PetscValidHeaderSpecific(B,MAT_CLASSID,3);
1028   if (A) PetscCheckSameComm(ts,1,A,2);
1029   if (B) PetscCheckSameComm(ts,1,B,3);
1030 
1031   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
1032   ierr = DMTSSetIJacobian(dm,f,ctx);CHKERRQ(ierr);
1033 
1034   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
1035   ierr = SNESSetJacobian(snes,A,B,SNESTSFormJacobian,ts);CHKERRQ(ierr);
1036   PetscFunctionReturn(0);
1037 }
1038 
1039 #undef __FUNCT__
1040 #define __FUNCT__ "TSLoad"
1041 /*@C
1042   TSLoad - Loads a KSP that has been stored in binary  with KSPView().
1043 
1044   Collective on PetscViewer
1045 
1046   Input Parameters:
1047 + newdm - the newly loaded TS, this needs to have been created with TSCreate() or
1048            some related function before a call to TSLoad().
1049 - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()
1050 
1051    Level: intermediate
1052 
1053   Notes:
1054    The type is determined by the data in the file, any type set into the TS before this call is ignored.
1055 
1056   Notes for advanced users:
1057   Most users should not need to know the details of the binary storage
1058   format, since TSLoad() and TSView() completely hide these details.
1059   But for anyone who's interested, the standard binary matrix storage
1060   format is
1061 .vb
1062      has not yet been determined
1063 .ve
1064 
1065 .seealso: PetscViewerBinaryOpen(), TSView(), MatLoad(), VecLoad()
1066 @*/
1067 PetscErrorCode  TSLoad(TS ts, PetscViewer viewer)
1068 {
1069   PetscErrorCode ierr;
1070   PetscBool      isbinary;
1071   PetscInt       classid;
1072   char           type[256];
1073   DMTS           sdm;
1074   DM             dm;
1075 
1076   PetscFunctionBegin;
1077   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1078   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
1079   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
1080   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");
1081 
1082   ierr = PetscViewerBinaryRead(viewer,&classid,1,PETSC_INT);CHKERRQ(ierr);
1083   if (classid != TS_FILE_CLASSID) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_ARG_WRONG,"Not TS next in file");
1084   ierr = PetscViewerBinaryRead(viewer,type,256,PETSC_CHAR);CHKERRQ(ierr);
1085   ierr = TSSetType(ts, type);CHKERRQ(ierr);
1086   if (ts->ops->load) {
1087     ierr = (*ts->ops->load)(ts,viewer);CHKERRQ(ierr);
1088   }
1089   ierr = DMCreate(((PetscObject)ts)->comm,&dm);CHKERRQ(ierr);
1090   ierr = DMLoad(dm,viewer);CHKERRQ(ierr);
1091   ierr = TSSetDM(ts,dm);CHKERRQ(ierr);
1092   ierr = DMCreateGlobalVector(ts->dm,&ts->vec_sol);CHKERRQ(ierr);
1093   ierr = VecLoad(ts->vec_sol,viewer);CHKERRQ(ierr);
1094   ierr = DMGetDMTS(ts->dm,&sdm);CHKERRQ(ierr);
1095   ierr = DMTSLoad(sdm,viewer);CHKERRQ(ierr);
1096   PetscFunctionReturn(0);
1097 }
1098 
1099 #undef __FUNCT__
1100 #define __FUNCT__ "TSView"
1101 /*@C
1102     TSView - Prints the TS data structure.
1103 
1104     Collective on TS
1105 
1106     Input Parameters:
1107 +   ts - the TS context obtained from TSCreate()
1108 -   viewer - visualization context
1109 
1110     Options Database Key:
1111 .   -ts_view - calls TSView() at end of TSStep()
1112 
1113     Notes:
1114     The available visualization contexts include
1115 +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
1116 -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
1117          output where only the first processor opens
1118          the file.  All other processors send their
1119          data to the first processor to print.
1120 
1121     The user can open an alternative visualization context with
1122     PetscViewerASCIIOpen() - output to a specified file.
1123 
1124     Level: beginner
1125 
1126 .keywords: TS, timestep, view
1127 
1128 .seealso: PetscViewerASCIIOpen()
1129 @*/
1130 PetscErrorCode  TSView(TS ts,PetscViewer viewer)
1131 {
1132   PetscErrorCode ierr;
1133   TSType         type;
1134   PetscBool      iascii,isstring,isundials,isbinary,isdraw;
1135   DMTS           sdm;
1136 
1137   PetscFunctionBegin;
1138   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1139   if (!viewer) {
1140     ierr = PetscViewerASCIIGetStdout(((PetscObject)ts)->comm,&viewer);CHKERRQ(ierr);
1141   }
1142   PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,2);
1143   PetscCheckSameComm(ts,1,viewer,2);
1144 
1145   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
1146   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
1147   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);CHKERRQ(ierr);
1148   ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
1149   if (iascii) {
1150     ierr = PetscObjectPrintClassNamePrefixType((PetscObject)ts,viewer,"TS Object");CHKERRQ(ierr);
1151     ierr = PetscViewerASCIIPrintf(viewer,"  maximum steps=%D\n",ts->max_steps);CHKERRQ(ierr);
1152     ierr = PetscViewerASCIIPrintf(viewer,"  maximum time=%G\n",ts->max_time);CHKERRQ(ierr);
1153     if (ts->problem_type == TS_NONLINEAR) {
1154       ierr = PetscViewerASCIIPrintf(viewer,"  total number of nonlinear solver iterations=%D\n",ts->snes_its);CHKERRQ(ierr);
1155       ierr = PetscViewerASCIIPrintf(viewer,"  total number of nonlinear solve failures=%D\n",ts->num_snes_failures);CHKERRQ(ierr);
1156     }
1157     ierr = PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",ts->ksp_its);CHKERRQ(ierr);
1158     ierr = PetscViewerASCIIPrintf(viewer,"  total number of rejected steps=%D\n",ts->reject);CHKERRQ(ierr);
1159     ierr = DMGetDMTS(ts->dm,&sdm);CHKERRQ(ierr);
1160     ierr = DMTSView(sdm,viewer);CHKERRQ(ierr);
1161     if (ts->ops->view) {
1162       ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
1163       ierr = (*ts->ops->view)(ts,viewer);CHKERRQ(ierr);
1164       ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
1165     }
1166   } else if (isstring) {
1167     ierr = TSGetType(ts,&type);CHKERRQ(ierr);
1168     ierr = PetscViewerStringSPrintf(viewer," %-7.7s",type);CHKERRQ(ierr);
1169   } else if (isbinary) {
1170     PetscInt         classid = TS_FILE_CLASSID;
1171     MPI_Comm         comm;
1172     PetscMPIInt      rank;
1173     char             type[256];
1174 
1175     ierr = PetscObjectGetComm((PetscObject)ts,&comm);CHKERRQ(ierr);
1176     ierr = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
1177     if (!rank) {
1178       ierr = PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);CHKERRQ(ierr);
1179       ierr = PetscStrncpy(type,((PetscObject)ts)->type_name,256);CHKERRQ(ierr);
1180       ierr = PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);CHKERRQ(ierr);
1181     }
1182     if (ts->ops->view) {
1183       ierr = (*ts->ops->view)(ts,viewer);CHKERRQ(ierr);
1184     }
1185     ierr = DMView(ts->dm,viewer);CHKERRQ(ierr);
1186     ierr = VecView(ts->vec_sol,viewer);CHKERRQ(ierr);
1187     ierr = DMGetDMTS(ts->dm,&sdm);CHKERRQ(ierr);
1188     ierr = DMTSView(sdm,viewer);CHKERRQ(ierr);
1189   } else if (isdraw) {
1190     PetscDraw draw;
1191     char      str[36];
1192     PetscReal x,y,bottom,h;
1193 
1194     ierr = PetscViewerDrawGetDraw(viewer,0,&draw);CHKERRQ(ierr);
1195     ierr = PetscDrawGetCurrentPoint(draw,&x,&y);CHKERRQ(ierr);
1196     ierr = PetscStrcpy(str,"TS: ");CHKERRQ(ierr);
1197     ierr = PetscStrcat(str,((PetscObject)ts)->type_name);CHKERRQ(ierr);
1198     ierr = PetscDrawBoxedString(draw,x,y,PETSC_DRAW_BLACK,PETSC_DRAW_BLACK,str,PETSC_NULL,&h);CHKERRQ(ierr);
1199     bottom = y - h;
1200     ierr = PetscDrawPushCurrentPoint(draw,x,bottom);CHKERRQ(ierr);
1201     if (ts->ops->view) {
1202       ierr = (*ts->ops->view)(ts,viewer);CHKERRQ(ierr);
1203     }
1204     ierr = PetscDrawPopCurrentPoint(draw);CHKERRQ(ierr);
1205   }
1206   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
1207   ierr = PetscObjectTypeCompare((PetscObject)ts,TSSUNDIALS,&isundials);CHKERRQ(ierr);
1208   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
1209   PetscFunctionReturn(0);
1210 }
1211 
1212 
1213 #undef __FUNCT__
1214 #define __FUNCT__ "TSSetApplicationContext"
1215 /*@
1216    TSSetApplicationContext - Sets an optional user-defined context for
1217    the timesteppers.
1218 
1219    Logically Collective on TS
1220 
1221    Input Parameters:
1222 +  ts - the TS context obtained from TSCreate()
1223 -  usrP - optional user context
1224 
1225    Level: intermediate
1226 
1227 .keywords: TS, timestep, set, application, context
1228 
1229 .seealso: TSGetApplicationContext()
1230 @*/
1231 PetscErrorCode  TSSetApplicationContext(TS ts,void *usrP)
1232 {
1233   PetscFunctionBegin;
1234   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1235   ts->user = usrP;
1236   PetscFunctionReturn(0);
1237 }
1238 
1239 #undef __FUNCT__
1240 #define __FUNCT__ "TSGetApplicationContext"
1241 /*@
1242     TSGetApplicationContext - Gets the user-defined context for the
1243     timestepper.
1244 
1245     Not Collective
1246 
1247     Input Parameter:
1248 .   ts - the TS context obtained from TSCreate()
1249 
1250     Output Parameter:
1251 .   usrP - user context
1252 
1253     Level: intermediate
1254 
1255 .keywords: TS, timestep, get, application, context
1256 
1257 .seealso: TSSetApplicationContext()
1258 @*/
1259 PetscErrorCode  TSGetApplicationContext(TS ts,void *usrP)
1260 {
1261   PetscFunctionBegin;
1262   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1263   *(void**)usrP = ts->user;
1264   PetscFunctionReturn(0);
1265 }
1266 
1267 #undef __FUNCT__
1268 #define __FUNCT__ "TSGetTimeStepNumber"
1269 /*@
1270    TSGetTimeStepNumber - Gets the number of time steps completed.
1271 
1272    Not Collective
1273 
1274    Input Parameter:
1275 .  ts - the TS context obtained from TSCreate()
1276 
1277    Output Parameter:
1278 .  iter - number of steps completed so far
1279 
1280    Level: intermediate
1281 
1282 .keywords: TS, timestep, get, iteration, number
1283 .seealso: TSGetTime(), TSGetTimeStep(), TSSetPreStep(), TSSetPreStage(), TSSetPostStep()
1284 @*/
1285 PetscErrorCode  TSGetTimeStepNumber(TS ts,PetscInt* iter)
1286 {
1287   PetscFunctionBegin;
1288   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1289   PetscValidIntPointer(iter,2);
1290   *iter = ts->steps;
1291   PetscFunctionReturn(0);
1292 }
1293 
1294 #undef __FUNCT__
1295 #define __FUNCT__ "TSSetInitialTimeStep"
1296 /*@
1297    TSSetInitialTimeStep - Sets the initial timestep to be used,
1298    as well as the initial time.
1299 
1300    Logically Collective on TS
1301 
1302    Input Parameters:
1303 +  ts - the TS context obtained from TSCreate()
1304 .  initial_time - the initial time
1305 -  time_step - the size of the timestep
1306 
1307    Level: intermediate
1308 
1309 .seealso: TSSetTimeStep(), TSGetTimeStep()
1310 
1311 .keywords: TS, set, initial, timestep
1312 @*/
1313 PetscErrorCode  TSSetInitialTimeStep(TS ts,PetscReal initial_time,PetscReal time_step)
1314 {
1315   PetscErrorCode ierr;
1316 
1317   PetscFunctionBegin;
1318   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1319   ierr = TSSetTimeStep(ts,time_step);CHKERRQ(ierr);
1320   ierr = TSSetTime(ts,initial_time);CHKERRQ(ierr);
1321   PetscFunctionReturn(0);
1322 }
1323 
1324 #undef __FUNCT__
1325 #define __FUNCT__ "TSSetTimeStep"
1326 /*@
1327    TSSetTimeStep - Allows one to reset the timestep at any time,
1328    useful for simple pseudo-timestepping codes.
1329 
1330    Logically Collective on TS
1331 
1332    Input Parameters:
1333 +  ts - the TS context obtained from TSCreate()
1334 -  time_step - the size of the timestep
1335 
1336    Level: intermediate
1337 
1338 .seealso: TSSetInitialTimeStep(), TSGetTimeStep()
1339 
1340 .keywords: TS, set, timestep
1341 @*/
1342 PetscErrorCode  TSSetTimeStep(TS ts,PetscReal time_step)
1343 {
1344   PetscFunctionBegin;
1345   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1346   PetscValidLogicalCollectiveReal(ts,time_step,2);
1347   ts->time_step = time_step;
1348   ts->time_step_orig = time_step;
1349   PetscFunctionReturn(0);
1350 }
1351 
1352 #undef __FUNCT__
1353 #define __FUNCT__ "TSSetExactFinalTime"
1354 /*@
1355    TSSetExactFinalTime - Determines whether to adapt the final time step to
1356      match the exact final time, interpolate solution to the exact final time,
1357      or just return at the final time TS computed.
1358 
1359   Logically Collective on TS
1360 
1361    Input Parameter:
1362 +   ts - the time-step context
1363 -   eftopt - exact final time option
1364 
1365    Level: beginner
1366 
1367 .seealso: TSExactFinalTime
1368 @*/
1369 PetscErrorCode  TSSetExactFinalTime(TS ts,TSExactFinalTimeOption eftopt)
1370 {
1371   PetscFunctionBegin;
1372   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1373   PetscValidLogicalCollectiveEnum(ts,eftopt,2);
1374   ts->exact_final_time = eftopt;
1375   PetscFunctionReturn(0);
1376 }
1377 
1378 #undef __FUNCT__
1379 #define __FUNCT__ "TSGetTimeStep"
1380 /*@
1381    TSGetTimeStep - Gets the current timestep size.
1382 
1383    Not Collective
1384 
1385    Input Parameter:
1386 .  ts - the TS context obtained from TSCreate()
1387 
1388    Output Parameter:
1389 .  dt - the current timestep size
1390 
1391    Level: intermediate
1392 
1393 .seealso: TSSetInitialTimeStep(), TSGetTimeStep()
1394 
1395 .keywords: TS, get, timestep
1396 @*/
1397 PetscErrorCode  TSGetTimeStep(TS ts,PetscReal* dt)
1398 {
1399   PetscFunctionBegin;
1400   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1401   PetscValidRealPointer(dt,2);
1402   *dt = ts->time_step;
1403   PetscFunctionReturn(0);
1404 }
1405 
1406 #undef __FUNCT__
1407 #define __FUNCT__ "TSGetSolution"
1408 /*@
1409    TSGetSolution - Returns the solution at the present timestep. It
1410    is valid to call this routine inside the function that you are evaluating
1411    in order to move to the new timestep. This vector not changed until
1412    the solution at the next timestep has been calculated.
1413 
1414    Not Collective, but Vec returned is parallel if TS is parallel
1415 
1416    Input Parameter:
1417 .  ts - the TS context obtained from TSCreate()
1418 
1419    Output Parameter:
1420 .  v - the vector containing the solution
1421 
1422    Level: intermediate
1423 
1424 .seealso: TSGetTimeStep()
1425 
1426 .keywords: TS, timestep, get, solution
1427 @*/
1428 PetscErrorCode  TSGetSolution(TS ts,Vec *v)
1429 {
1430   PetscFunctionBegin;
1431   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1432   PetscValidPointer(v,2);
1433   *v = ts->vec_sol;
1434   PetscFunctionReturn(0);
1435 }
1436 
1437 /* ----- Routines to initialize and destroy a timestepper ---- */
1438 #undef __FUNCT__
1439 #define __FUNCT__ "TSSetProblemType"
1440 /*@
1441   TSSetProblemType - Sets the type of problem to be solved.
1442 
1443   Not collective
1444 
1445   Input Parameters:
1446 + ts   - The TS
1447 - type - One of TS_LINEAR, TS_NONLINEAR where these types refer to problems of the forms
1448 .vb
1449          U_t - A U = 0      (linear)
1450          U_t - A(t) U = 0   (linear)
1451          F(t,U,U_t) = 0     (nonlinear)
1452 .ve
1453 
1454    Level: beginner
1455 
1456 .keywords: TS, problem type
1457 .seealso: TSSetUp(), TSProblemType, TS
1458 @*/
1459 PetscErrorCode  TSSetProblemType(TS ts, TSProblemType type)
1460 {
1461   PetscErrorCode ierr;
1462 
1463   PetscFunctionBegin;
1464   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
1465   ts->problem_type = type;
1466   if (type == TS_LINEAR) {
1467     SNES snes;
1468     ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
1469     ierr = SNESSetType(snes,SNESKSPONLY);CHKERRQ(ierr);
1470   }
1471   PetscFunctionReturn(0);
1472 }
1473 
1474 #undef __FUNCT__
1475 #define __FUNCT__ "TSGetProblemType"
1476 /*@C
1477   TSGetProblemType - Gets the type of problem to be solved.
1478 
1479   Not collective
1480 
1481   Input Parameter:
1482 . ts   - The TS
1483 
1484   Output Parameter:
1485 . type - One of TS_LINEAR, TS_NONLINEAR where these types refer to problems of the forms
1486 .vb
1487          M U_t = A U
1488          M(t) U_t = A(t) U
1489          F(t,U,U_t)
1490 .ve
1491 
1492    Level: beginner
1493 
1494 .keywords: TS, problem type
1495 .seealso: TSSetUp(), TSProblemType, TS
1496 @*/
1497 PetscErrorCode  TSGetProblemType(TS ts, TSProblemType *type)
1498 {
1499   PetscFunctionBegin;
1500   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
1501   PetscValidIntPointer(type,2);
1502   *type = ts->problem_type;
1503   PetscFunctionReturn(0);
1504 }
1505 
1506 #undef __FUNCT__
1507 #define __FUNCT__ "TSSetUp"
1508 /*@
1509    TSSetUp - Sets up the internal data structures for the later use
1510    of a timestepper.
1511 
1512    Collective on TS
1513 
1514    Input Parameter:
1515 .  ts - the TS context obtained from TSCreate()
1516 
1517    Notes:
1518    For basic use of the TS solvers the user need not explicitly call
1519    TSSetUp(), since these actions will automatically occur during
1520    the call to TSStep().  However, if one wishes to control this
1521    phase separately, TSSetUp() should be called after TSCreate()
1522    and optional routines of the form TSSetXXX(), but before TSStep().
1523 
1524    Level: advanced
1525 
1526 .keywords: TS, timestep, setup
1527 
1528 .seealso: TSCreate(), TSStep(), TSDestroy()
1529 @*/
1530 PetscErrorCode  TSSetUp(TS ts)
1531 {
1532   PetscErrorCode ierr;
1533   DM             dm;
1534   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
1535   PetscErrorCode (*jac)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
1536   TSIJacobian    ijac;
1537   TSRHSJacobian  rhsjac;
1538 
1539   PetscFunctionBegin;
1540   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1541   if (ts->setupcalled) PetscFunctionReturn(0);
1542 
1543   if (!((PetscObject)ts)->type_name) {
1544     ierr = TSSetType(ts,TSEULER);CHKERRQ(ierr);
1545   }
1546 
1547   if (!ts->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Must call TSSetSolution() first");
1548 
1549   ierr = TSGetTSAdapt(ts,&ts->adapt);CHKERRQ(ierr);
1550 
1551   if (ts->ops->setup) {
1552     ierr = (*ts->ops->setup)(ts);CHKERRQ(ierr);
1553   }
1554 
1555   /* in the case where we've set a DMTSFunction or what have you, we need the default SNESFunction
1556    to be set right but can't do it elsewhere due to the overreliance on ctx=ts.
1557    */
1558   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
1559   ierr = DMSNESGetFunction(dm,&func,PETSC_NULL);CHKERRQ(ierr);
1560   if (!func) {
1561     ierr =DMSNESSetFunction(dm,SNESTSFormFunction,ts);CHKERRQ(ierr);
1562   }
1563   /* if the SNES doesn't have a jacobian set and the TS has an ijacobian or rhsjacobian set, set the SNES to use it.
1564      Otherwise, the SNES will use coloring internally to form the Jacobian.
1565    */
1566   ierr = DMSNESGetJacobian(dm,&jac,PETSC_NULL);CHKERRQ(ierr);
1567   ierr = DMTSGetIJacobian(dm,&ijac,PETSC_NULL);CHKERRQ(ierr);
1568   ierr = DMTSGetRHSJacobian(dm,&rhsjac,PETSC_NULL);CHKERRQ(ierr);
1569   if (!jac && (ijac || rhsjac)) {
1570     ierr = DMSNESSetJacobian(dm,SNESTSFormJacobian,ts);CHKERRQ(ierr);
1571   }
1572   ts->setupcalled = PETSC_TRUE;
1573   PetscFunctionReturn(0);
1574 }
1575 
1576 #undef __FUNCT__
1577 #define __FUNCT__ "TSReset"
1578 /*@
1579    TSReset - Resets a TS context and removes any allocated Vecs and Mats.
1580 
1581    Collective on TS
1582 
1583    Input Parameter:
1584 .  ts - the TS context obtained from TSCreate()
1585 
1586    Level: beginner
1587 
1588 .keywords: TS, timestep, reset
1589 
1590 .seealso: TSCreate(), TSSetup(), TSDestroy()
1591 @*/
1592 PetscErrorCode  TSReset(TS ts)
1593 {
1594   PetscErrorCode ierr;
1595 
1596   PetscFunctionBegin;
1597   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1598   if (ts->ops->reset) {
1599     ierr = (*ts->ops->reset)(ts);CHKERRQ(ierr);
1600   }
1601   if (ts->snes) {ierr = SNESReset(ts->snes);CHKERRQ(ierr);}
1602   ierr = MatDestroy(&ts->Arhs);CHKERRQ(ierr);
1603   ierr = MatDestroy(&ts->Brhs);CHKERRQ(ierr);
1604   ierr = VecDestroy(&ts->Frhs);CHKERRQ(ierr);
1605   ierr = VecDestroy(&ts->vec_sol);CHKERRQ(ierr);
1606   ierr = VecDestroy(&ts->vatol);CHKERRQ(ierr);
1607   ierr = VecDestroy(&ts->vrtol);CHKERRQ(ierr);
1608   ierr = VecDestroyVecs(ts->nwork,&ts->work);CHKERRQ(ierr);
1609   ts->setupcalled = PETSC_FALSE;
1610   PetscFunctionReturn(0);
1611 }
1612 
1613 #undef __FUNCT__
1614 #define __FUNCT__ "TSDestroy"
1615 /*@
1616    TSDestroy - Destroys the timestepper context that was created
1617    with TSCreate().
1618 
1619    Collective on TS
1620 
1621    Input Parameter:
1622 .  ts - the TS context obtained from TSCreate()
1623 
1624    Level: beginner
1625 
1626 .keywords: TS, timestepper, destroy
1627 
1628 .seealso: TSCreate(), TSSetUp(), TSSolve()
1629 @*/
1630 PetscErrorCode  TSDestroy(TS *ts)
1631 {
1632   PetscErrorCode ierr;
1633 
1634   PetscFunctionBegin;
1635   if (!*ts) PetscFunctionReturn(0);
1636   PetscValidHeaderSpecific((*ts),TS_CLASSID,1);
1637   if (--((PetscObject)(*ts))->refct > 0) {*ts = 0; PetscFunctionReturn(0);}
1638 
1639   ierr = TSReset((*ts));CHKERRQ(ierr);
1640 
1641   /* if memory was published with AMS then destroy it */
1642   ierr = PetscObjectDepublish((*ts));CHKERRQ(ierr);
1643   if ((*ts)->ops->destroy) {ierr = (*(*ts)->ops->destroy)((*ts));CHKERRQ(ierr);}
1644 
1645   ierr = TSAdaptDestroy(&(*ts)->adapt);CHKERRQ(ierr);
1646   ierr = SNESDestroy(&(*ts)->snes);CHKERRQ(ierr);
1647   ierr = DMDestroy(&(*ts)->dm);CHKERRQ(ierr);
1648   ierr = TSMonitorCancel((*ts));CHKERRQ(ierr);
1649 
1650   ierr = PetscHeaderDestroy(ts);CHKERRQ(ierr);
1651   PetscFunctionReturn(0);
1652 }
1653 
1654 #undef __FUNCT__
1655 #define __FUNCT__ "TSGetSNES"
1656 /*@
1657    TSGetSNES - Returns the SNES (nonlinear solver) associated with
1658    a TS (timestepper) context. Valid only for nonlinear problems.
1659 
1660    Not Collective, but SNES is parallel if TS is parallel
1661 
1662    Input Parameter:
1663 .  ts - the TS context obtained from TSCreate()
1664 
1665    Output Parameter:
1666 .  snes - the nonlinear solver context
1667 
1668    Notes:
1669    The user can then directly manipulate the SNES context to set various
1670    options, etc.  Likewise, the user can then extract and manipulate the
1671    KSP, KSP, and PC contexts as well.
1672 
1673    TSGetSNES() does not work for integrators that do not use SNES; in
1674    this case TSGetSNES() returns PETSC_NULL in snes.
1675 
1676    Level: beginner
1677 
1678 .keywords: timestep, get, SNES
1679 @*/
1680 PetscErrorCode  TSGetSNES(TS ts,SNES *snes)
1681 {
1682   PetscErrorCode ierr;
1683 
1684   PetscFunctionBegin;
1685   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1686   PetscValidPointer(snes,2);
1687   if (!ts->snes) {
1688     ierr = SNESCreate(((PetscObject)ts)->comm,&ts->snes);CHKERRQ(ierr);
1689     ierr = SNESSetFunction(ts->snes,PETSC_NULL,SNESTSFormFunction,ts);CHKERRQ(ierr);
1690     ierr = PetscLogObjectParent(ts,ts->snes);CHKERRQ(ierr);
1691     ierr = PetscObjectIncrementTabLevel((PetscObject)ts->snes,(PetscObject)ts,1);CHKERRQ(ierr);
1692     if (ts->dm) {ierr = SNESSetDM(ts->snes,ts->dm);CHKERRQ(ierr);}
1693     if (ts->problem_type == TS_LINEAR) {
1694       ierr = SNESSetType(ts->snes,SNESKSPONLY);CHKERRQ(ierr);
1695     }
1696   }
1697   *snes = ts->snes;
1698   PetscFunctionReturn(0);
1699 }
1700 
1701 #undef __FUNCT__
1702 #define __FUNCT__ "TSGetKSP"
1703 /*@
1704    TSGetKSP - Returns the KSP (linear solver) associated with
1705    a TS (timestepper) context.
1706 
1707    Not Collective, but KSP is parallel if TS is parallel
1708 
1709    Input Parameter:
1710 .  ts - the TS context obtained from TSCreate()
1711 
1712    Output Parameter:
1713 .  ksp - the nonlinear solver context
1714 
1715    Notes:
1716    The user can then directly manipulate the KSP context to set various
1717    options, etc.  Likewise, the user can then extract and manipulate the
1718    KSP and PC contexts as well.
1719 
1720    TSGetKSP() does not work for integrators that do not use KSP;
1721    in this case TSGetKSP() returns PETSC_NULL in ksp.
1722 
1723    Level: beginner
1724 
1725 .keywords: timestep, get, KSP
1726 @*/
1727 PetscErrorCode  TSGetKSP(TS ts,KSP *ksp)
1728 {
1729   PetscErrorCode ierr;
1730   SNES           snes;
1731 
1732   PetscFunctionBegin;
1733   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1734   PetscValidPointer(ksp,2);
1735   if (!((PetscObject)ts)->type_name) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_NULL,"KSP is not created yet. Call TSSetType() first");
1736   if (ts->problem_type != TS_LINEAR) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Linear only; use TSGetSNES()");
1737   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
1738   ierr = SNESGetKSP(snes,ksp);CHKERRQ(ierr);
1739   PetscFunctionReturn(0);
1740 }
1741 
1742 /* ----------- Routines to set solver parameters ---------- */
1743 
1744 #undef __FUNCT__
1745 #define __FUNCT__ "TSGetDuration"
1746 /*@
1747    TSGetDuration - Gets the maximum number of timesteps to use and
1748    maximum time for iteration.
1749 
1750    Not Collective
1751 
1752    Input Parameters:
1753 +  ts       - the TS context obtained from TSCreate()
1754 .  maxsteps - maximum number of iterations to use, or PETSC_NULL
1755 -  maxtime  - final time to iterate to, or PETSC_NULL
1756 
1757    Level: intermediate
1758 
1759 .keywords: TS, timestep, get, maximum, iterations, time
1760 @*/
1761 PetscErrorCode  TSGetDuration(TS ts, PetscInt *maxsteps, PetscReal *maxtime)
1762 {
1763   PetscFunctionBegin;
1764   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
1765   if (maxsteps) {
1766     PetscValidIntPointer(maxsteps,2);
1767     *maxsteps = ts->max_steps;
1768   }
1769   if (maxtime) {
1770     PetscValidScalarPointer(maxtime,3);
1771     *maxtime  = ts->max_time;
1772   }
1773   PetscFunctionReturn(0);
1774 }
1775 
1776 #undef __FUNCT__
1777 #define __FUNCT__ "TSSetDuration"
1778 /*@
1779    TSSetDuration - Sets the maximum number of timesteps to use and
1780    maximum time for iteration.
1781 
1782    Logically Collective on TS
1783 
1784    Input Parameters:
1785 +  ts - the TS context obtained from TSCreate()
1786 .  maxsteps - maximum number of iterations to use
1787 -  maxtime - final time to iterate to
1788 
1789    Options Database Keys:
1790 .  -ts_max_steps <maxsteps> - Sets maxsteps
1791 .  -ts_final_time <maxtime> - Sets maxtime
1792 
1793    Notes:
1794    The default maximum number of iterations is 5000. Default time is 5.0
1795 
1796    Level: intermediate
1797 
1798 .keywords: TS, timestep, set, maximum, iterations
1799 
1800 .seealso: TSSetExactFinalTime()
1801 @*/
1802 PetscErrorCode  TSSetDuration(TS ts,PetscInt maxsteps,PetscReal maxtime)
1803 {
1804   PetscFunctionBegin;
1805   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1806   PetscValidLogicalCollectiveInt(ts,maxsteps,2);
1807   PetscValidLogicalCollectiveReal(ts,maxtime,2);
1808   if (maxsteps >= 0) ts->max_steps = maxsteps;
1809   if (maxtime != PETSC_DEFAULT) ts->max_time  = maxtime;
1810   PetscFunctionReturn(0);
1811 }
1812 
1813 #undef __FUNCT__
1814 #define __FUNCT__ "TSSetSolution"
1815 /*@
1816    TSSetSolution - Sets the initial solution vector
1817    for use by the TS routines.
1818 
1819    Logically Collective on TS and Vec
1820 
1821    Input Parameters:
1822 +  ts - the TS context obtained from TSCreate()
1823 -  u - the solution vector
1824 
1825    Level: beginner
1826 
1827 .keywords: TS, timestep, set, solution, initial conditions
1828 @*/
1829 PetscErrorCode  TSSetSolution(TS ts,Vec u)
1830 {
1831   PetscErrorCode ierr;
1832   DM             dm;
1833 
1834   PetscFunctionBegin;
1835   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1836   PetscValidHeaderSpecific(u,VEC_CLASSID,2);
1837   ierr = PetscObjectReference((PetscObject)u);CHKERRQ(ierr);
1838   ierr = VecDestroy(&ts->vec_sol);CHKERRQ(ierr);
1839   ts->vec_sol = u;
1840   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
1841   ierr = DMShellSetGlobalVector(dm,u);CHKERRQ(ierr);
1842   PetscFunctionReturn(0);
1843 }
1844 
1845 #undef __FUNCT__
1846 #define __FUNCT__ "TSSetPreStep"
1847 /*@C
1848   TSSetPreStep - Sets the general-purpose function
1849   called once at the beginning of each time step.
1850 
1851   Logically Collective on TS
1852 
1853   Input Parameters:
1854 + ts   - The TS context obtained from TSCreate()
1855 - func - The function
1856 
1857   Calling sequence of func:
1858 . func (TS ts);
1859 
1860   Level: intermediate
1861 
1862   Note:
1863   If a step is rejected, TSStep() will call this routine again before each attempt.
1864   The last completed time step number can be queried using TSGetTimeStepNumber(), the
1865   size of the step being attempted can be obtained using TSGetTimeStep().
1866 
1867 .keywords: TS, timestep
1868 .seealso: TSSetPreStage(), TSSetPostStep(), TSStep()
1869 @*/
1870 PetscErrorCode  TSSetPreStep(TS ts, PetscErrorCode (*func)(TS))
1871 {
1872   PetscFunctionBegin;
1873   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
1874   ts->ops->prestep = func;
1875   PetscFunctionReturn(0);
1876 }
1877 
1878 #undef __FUNCT__
1879 #define __FUNCT__ "TSPreStep"
1880 /*@
1881   TSPreStep - Runs the user-defined pre-step function.
1882 
1883   Collective on TS
1884 
1885   Input Parameters:
1886 . ts   - The TS context obtained from TSCreate()
1887 
1888   Notes:
1889   TSPreStep() is typically used within time stepping implementations,
1890   so most users would not generally call this routine themselves.
1891 
1892   Level: developer
1893 
1894 .keywords: TS, timestep
1895 .seealso: TSSetPreStep(), TSPreStage(), TSPostStep()
1896 @*/
1897 PetscErrorCode  TSPreStep(TS ts)
1898 {
1899   PetscErrorCode ierr;
1900 
1901   PetscFunctionBegin;
1902   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1903   if (ts->ops->prestep) {
1904     PetscStackPush("TS PreStep function");
1905     ierr = (*ts->ops->prestep)(ts);CHKERRQ(ierr);
1906     PetscStackPop;
1907   }
1908   PetscFunctionReturn(0);
1909 }
1910 
1911 #undef __FUNCT__
1912 #define __FUNCT__ "TSSetPreStage"
1913 /*@C
1914   TSSetPreStage - Sets the general-purpose function
1915   called once at the beginning of each stage.
1916 
1917   Logically Collective on TS
1918 
1919   Input Parameters:
1920 + ts   - The TS context obtained from TSCreate()
1921 - func - The function
1922 
1923   Calling sequence of func:
1924 . PetscErrorCode func(TS ts, PetscReal stagetime);
1925 
1926   Level: intermediate
1927 
1928   Note:
1929   There may be several stages per time step. If the solve for a given stage fails, the step may be rejected and retried.
1930   The time step number being computed can be queried using TSGetTimeStepNumber() and the total size of the step being
1931   attempted can be obtained using TSGetTimeStep(). The time at the start of the step is available via TSGetTime().
1932 
1933 .keywords: TS, timestep
1934 .seealso: TSSetPreStep(), TSSetPostStep(), TSGetApplicationContext()
1935 @*/
1936 PetscErrorCode  TSSetPreStage(TS ts, PetscErrorCode (*func)(TS,PetscReal))
1937 {
1938   PetscFunctionBegin;
1939   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
1940   ts->ops->prestage = func;
1941   PetscFunctionReturn(0);
1942 }
1943 
1944 #undef __FUNCT__
1945 #define __FUNCT__ "TSPreStage"
1946 /*@
1947   TSPreStage - Runs the user-defined pre-stage function set using TSSetPreStage()
1948 
1949   Collective on TS
1950 
1951   Input Parameters:
1952 . ts   - The TS context obtained from TSCreate()
1953 
1954   Notes:
1955   TSPreStage() is typically used within time stepping implementations,
1956   most users would not generally call this routine themselves.
1957 
1958   Level: developer
1959 
1960 .keywords: TS, timestep
1961 .seealso: TSSetPreStep(), TSPreStep(), TSPostStep()
1962 @*/
1963 PetscErrorCode  TSPreStage(TS ts, PetscReal stagetime)
1964 {
1965   PetscErrorCode ierr;
1966 
1967   PetscFunctionBegin;
1968   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
1969   if (ts->ops->prestage) {
1970     PetscStackPush("TS PreStage function");
1971     ierr = (*ts->ops->prestage)(ts,stagetime);CHKERRQ(ierr);
1972     PetscStackPop;
1973   }
1974   PetscFunctionReturn(0);
1975 }
1976 
1977 #undef __FUNCT__
1978 #define __FUNCT__ "TSSetPostStep"
1979 /*@C
1980   TSSetPostStep - Sets the general-purpose function
1981   called once at the end of each time step.
1982 
1983   Logically Collective on TS
1984 
1985   Input Parameters:
1986 + ts   - The TS context obtained from TSCreate()
1987 - func - The function
1988 
1989   Calling sequence of func:
1990 $ func (TS ts);
1991 
1992   Level: intermediate
1993 
1994 .keywords: TS, timestep
1995 .seealso: TSSetPreStep(), TSSetPreStage(), TSGetTimeStep(), TSGetTimeStepNumber(), TSGetTime()
1996 @*/
1997 PetscErrorCode  TSSetPostStep(TS ts, PetscErrorCode (*func)(TS))
1998 {
1999   PetscFunctionBegin;
2000   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
2001   ts->ops->poststep = func;
2002   PetscFunctionReturn(0);
2003 }
2004 
2005 #undef __FUNCT__
2006 #define __FUNCT__ "TSPostStep"
2007 /*@
2008   TSPostStep - Runs the user-defined post-step function.
2009 
2010   Collective on TS
2011 
2012   Input Parameters:
2013 . ts   - The TS context obtained from TSCreate()
2014 
2015   Notes:
2016   TSPostStep() is typically used within time stepping implementations,
2017   so most users would not generally call this routine themselves.
2018 
2019   Level: developer
2020 
2021 .keywords: TS, timestep
2022 @*/
2023 PetscErrorCode  TSPostStep(TS ts)
2024 {
2025   PetscErrorCode ierr;
2026 
2027   PetscFunctionBegin;
2028   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2029   if (ts->ops->poststep) {
2030     PetscStackPush("TS PostStep function");
2031     ierr = (*ts->ops->poststep)(ts);CHKERRQ(ierr);
2032     PetscStackPop;
2033   }
2034   PetscFunctionReturn(0);
2035 }
2036 
2037 /* ------------ Routines to set performance monitoring options ----------- */
2038 
2039 #undef __FUNCT__
2040 #define __FUNCT__ "TSMonitorSet"
2041 /*@C
2042    TSMonitorSet - Sets an ADDITIONAL function that is to be used at every
2043    timestep to display the iteration's  progress.
2044 
2045    Logically Collective on TS
2046 
2047    Input Parameters:
2048 +  ts - the TS context obtained from TSCreate()
2049 .  monitor - monitoring routine
2050 .  mctx - [optional] user-defined context for private data for the
2051              monitor routine (use PETSC_NULL if no context is desired)
2052 -  monitordestroy - [optional] routine that frees monitor context
2053           (may be PETSC_NULL)
2054 
2055    Calling sequence of monitor:
2056 $    int monitor(TS ts,PetscInt steps,PetscReal time,Vec u,void *mctx)
2057 
2058 +    ts - the TS context
2059 .    steps - iteration number (after the final time step the monitor routine is called with a step of -1, this is at the final time which may have
2060                                been interpolated to)
2061 .    time - current time
2062 .    u - current iterate
2063 -    mctx - [optional] monitoring context
2064 
2065    Notes:
2066    This routine adds an additional monitor to the list of monitors that
2067    already has been loaded.
2068 
2069    Fortran notes: Only a single monitor function can be set for each TS object
2070 
2071    Level: intermediate
2072 
2073 .keywords: TS, timestep, set, monitor
2074 
2075 .seealso: TSMonitorDefault(), TSMonitorCancel()
2076 @*/
2077 PetscErrorCode  TSMonitorSet(TS ts,PetscErrorCode (*monitor)(TS,PetscInt,PetscReal,Vec,void*),void *mctx,PetscErrorCode (*mdestroy)(void**))
2078 {
2079   PetscFunctionBegin;
2080   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2081   if (ts->numbermonitors >= MAXTSMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
2082   ts->monitor[ts->numbermonitors]           = monitor;
2083   ts->monitordestroy[ts->numbermonitors]    = mdestroy;
2084   ts->monitorcontext[ts->numbermonitors++]  = (void*)mctx;
2085   PetscFunctionReturn(0);
2086 }
2087 
2088 #undef __FUNCT__
2089 #define __FUNCT__ "TSMonitorCancel"
2090 /*@C
2091    TSMonitorCancel - Clears all the monitors that have been set on a time-step object.
2092 
2093    Logically Collective on TS
2094 
2095    Input Parameters:
2096 .  ts - the TS context obtained from TSCreate()
2097 
2098    Notes:
2099    There is no way to remove a single, specific monitor.
2100 
2101    Level: intermediate
2102 
2103 .keywords: TS, timestep, set, monitor
2104 
2105 .seealso: TSMonitorDefault(), TSMonitorSet()
2106 @*/
2107 PetscErrorCode  TSMonitorCancel(TS ts)
2108 {
2109   PetscErrorCode ierr;
2110   PetscInt       i;
2111 
2112   PetscFunctionBegin;
2113   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2114   for (i=0; i<ts->numbermonitors; i++) {
2115     if (ts->monitordestroy[i]) {
2116       ierr = (*ts->monitordestroy[i])(&ts->monitorcontext[i]);CHKERRQ(ierr);
2117     }
2118   }
2119   ts->numbermonitors = 0;
2120   PetscFunctionReturn(0);
2121 }
2122 
2123 #undef __FUNCT__
2124 #define __FUNCT__ "TSMonitorDefault"
2125 /*@
2126    TSMonitorDefault - Sets the Default monitor
2127 
2128    Level: intermediate
2129 
2130 .keywords: TS, set, monitor
2131 
2132 .seealso: TSMonitorDefault(), TSMonitorSet()
2133 @*/
2134 PetscErrorCode TSMonitorDefault(TS ts,PetscInt step,PetscReal ptime,Vec v,void *dummy)
2135 {
2136   PetscErrorCode ierr;
2137   PetscViewer    viewer = dummy ? (PetscViewer) dummy : PETSC_VIEWER_STDOUT_(((PetscObject)ts)->comm);
2138 
2139   PetscFunctionBegin;
2140   ierr = PetscViewerASCIIAddTab(viewer,((PetscObject)ts)->tablevel);CHKERRQ(ierr);
2141   ierr = PetscViewerASCIIPrintf(viewer,"%D TS dt %g time %g\n",step,(double)ts->time_step,(double)ptime);CHKERRQ(ierr);
2142   ierr = PetscViewerASCIISubtractTab(viewer,((PetscObject)ts)->tablevel);CHKERRQ(ierr);
2143   PetscFunctionReturn(0);
2144 }
2145 
2146 #undef __FUNCT__
2147 #define __FUNCT__ "TSSetRetainStages"
2148 /*@
2149    TSSetRetainStages - Request that all stages in the upcoming step be stored so that interpolation will be available.
2150 
2151    Logically Collective on TS
2152 
2153    Input Argument:
2154 .  ts - time stepping context
2155 
2156    Output Argument:
2157 .  flg - PETSC_TRUE or PETSC_FALSE
2158 
2159    Level: intermediate
2160 
2161 .keywords: TS, set
2162 
2163 .seealso: TSInterpolate(), TSSetPostStep()
2164 @*/
2165 PetscErrorCode TSSetRetainStages(TS ts,PetscBool flg)
2166 {
2167   PetscFunctionBegin;
2168   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2169   ts->retain_stages = flg;
2170   PetscFunctionReturn(0);
2171 }
2172 
2173 #undef __FUNCT__
2174 #define __FUNCT__ "TSInterpolate"
2175 /*@
2176    TSInterpolate - Interpolate the solution computed during the previous step to an arbitrary location in the interval
2177 
2178    Collective on TS
2179 
2180    Input Argument:
2181 +  ts - time stepping context
2182 -  t - time to interpolate to
2183 
2184    Output Argument:
2185 .  U - state at given time
2186 
2187    Notes:
2188    The user should call TSSetRetainStages() before taking a step in which interpolation will be requested.
2189 
2190    Level: intermediate
2191 
2192    Developer Notes:
2193    TSInterpolate() and the storing of previous steps/stages should be generalized to support delay differential equations and continuous adjoints.
2194 
2195 .keywords: TS, set
2196 
2197 .seealso: TSSetRetainStages(), TSSetPostStep()
2198 @*/
2199 PetscErrorCode TSInterpolate(TS ts,PetscReal t,Vec U)
2200 {
2201   PetscErrorCode ierr;
2202 
2203   PetscFunctionBegin;
2204   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2205   if (t < ts->ptime - ts->time_step_prev || t > ts->ptime) SETERRQ3(((PetscObject)ts)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Requested time %G not in last time steps [%G,%G]",t,ts->ptime-ts->time_step_prev,ts->ptime);
2206   if (!ts->ops->interpolate) SETERRQ1(((PetscObject)ts)->comm,PETSC_ERR_SUP,"%s does not provide interpolation",((PetscObject)ts)->type_name);
2207   ierr = (*ts->ops->interpolate)(ts,t,U);CHKERRQ(ierr);
2208   PetscFunctionReturn(0);
2209 }
2210 
2211 #undef __FUNCT__
2212 #define __FUNCT__ "TSStep"
2213 /*@
2214    TSStep - Steps one time step
2215 
2216    Collective on TS
2217 
2218    Input Parameter:
2219 .  ts - the TS context obtained from TSCreate()
2220 
2221    Level: intermediate
2222 
2223    Notes:
2224    The hook set using TSSetPreStep() is called before each attempt to take the step. In general, the time step size may
2225    be changed due to adaptive error controller or solve failures. Note that steps may contain multiple stages.
2226 
2227    This may over-step the final time provided in TSSetDuration() depending on the time-step used. TSSolve() interpolates to exactly the
2228    time provided in TSSetDuration(). One can use TSInterpolate() to determine an interpolated solution within the final timestep.
2229 
2230 .keywords: TS, timestep, solve
2231 
2232 .seealso: TSCreate(), TSSetUp(), TSDestroy(), TSSolve(), TSSetPreStep(), TSSetPreStage(), TSInterpolate()
2233 @*/
2234 PetscErrorCode  TSStep(TS ts)
2235 {
2236   PetscReal      ptime_prev;
2237   PetscErrorCode ierr;
2238 
2239   PetscFunctionBegin;
2240   PetscValidHeaderSpecific(ts, TS_CLASSID,1);
2241   ierr = TSSetUp(ts);CHKERRQ(ierr);
2242 
2243   ts->reason = TS_CONVERGED_ITERATING;
2244 
2245   ptime_prev = ts->ptime;
2246   ierr = PetscLogEventBegin(TS_Step,ts,0,0,0);CHKERRQ(ierr);
2247   ierr = (*ts->ops->step)(ts);CHKERRQ(ierr);
2248   ierr = PetscLogEventEnd(TS_Step,ts,0,0,0);CHKERRQ(ierr);
2249   ts->time_step_prev = ts->ptime - ptime_prev;
2250 
2251   if (ts->reason < 0) {
2252     if (ts->errorifstepfailed) {
2253       if (ts->reason == TS_DIVERGED_NONLINEAR_SOLVE) {
2254         SETERRQ1(((PetscObject)ts)->comm,PETSC_ERR_NOT_CONVERGED,"TSStep has failed due to %s, increase -ts_max_snes_failures or make negative to attempt recovery",TSConvergedReasons[ts->reason]);
2255       } else SETERRQ1(((PetscObject)ts)->comm,PETSC_ERR_NOT_CONVERGED,"TSStep has failed due to %s",TSConvergedReasons[ts->reason]);
2256     }
2257   } else if (!ts->reason) {
2258     if (ts->steps >= ts->max_steps)
2259       ts->reason = TS_CONVERGED_ITS;
2260     else if (ts->ptime >= ts->max_time)
2261       ts->reason = TS_CONVERGED_TIME;
2262   }
2263 
2264   PetscFunctionReturn(0);
2265 }
2266 
2267 #undef __FUNCT__
2268 #define __FUNCT__ "TSEvaluateStep"
2269 /*@
2270    TSEvaluateStep - Evaluate the solution at the end of a time step with a given order of accuracy.
2271 
2272    Collective on TS
2273 
2274    Input Arguments:
2275 +  ts - time stepping context
2276 .  order - desired order of accuracy
2277 -  done - whether the step was evaluated at this order (pass PETSC_NULL to generate an error if not available)
2278 
2279    Output Arguments:
2280 .  U - state at the end of the current step
2281 
2282    Level: advanced
2283 
2284    Notes:
2285    This function cannot be called until all stages have been evaluated.
2286    It is normally called by adaptive controllers before a step has been accepted and may also be called by the user after TSStep() has returned.
2287 
2288 .seealso: TSStep(), TSAdapt
2289 @*/
2290 PetscErrorCode TSEvaluateStep(TS ts,PetscInt order,Vec U,PetscBool *done)
2291 {
2292   PetscErrorCode ierr;
2293 
2294   PetscFunctionBegin;
2295   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2296   PetscValidType(ts,1);
2297   PetscValidHeaderSpecific(U,VEC_CLASSID,3);
2298   if (!ts->ops->evaluatestep) SETERRQ1(((PetscObject)ts)->comm,PETSC_ERR_SUP,"TSEvaluateStep not implemented for type '%s'",((PetscObject)ts)->type_name);
2299   ierr = (*ts->ops->evaluatestep)(ts,order,U,done);CHKERRQ(ierr);
2300   PetscFunctionReturn(0);
2301 }
2302 
2303 #undef __FUNCT__
2304 #define __FUNCT__ "TSSolve"
2305 /*@
2306    TSSolve - Steps the requested number of timesteps.
2307 
2308    Collective on TS
2309 
2310    Input Parameter:
2311 +  ts - the TS context obtained from TSCreate()
2312 -  u - the solution vector  (can be null if TSSetSolution() was used, otherwise must contain the initial conditions)
2313 
2314    Level: beginner
2315 
2316    Notes:
2317    The final time returned by this function may be different from the time of the internally
2318    held state accessible by TSGetSolution() and TSGetTime() because the method may have
2319    stepped over the final time.
2320 
2321 .keywords: TS, timestep, solve
2322 
2323 .seealso: TSCreate(), TSSetSolution(), TSStep()
2324 @*/
2325 PetscErrorCode TSSolve(TS ts,Vec u)
2326 {
2327   PetscBool      flg;
2328   PetscViewer    viewer;
2329   PetscErrorCode ierr;
2330 
2331   PetscFunctionBegin;
2332   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2333   if (u) PetscValidHeaderSpecific(u,VEC_CLASSID,2);
2334   if (ts->exact_final_time == TS_EXACTFINALTIME_INTERPOLATE) {   /* Need ts->vec_sol to be distinct so it is not overwritten when we interpolate at the end */
2335     if (!ts->vec_sol || u == ts->vec_sol) {
2336       Vec y;
2337       ierr = VecDuplicate(u,&y);CHKERRQ(ierr);
2338       ierr = TSSetSolution(ts,y);CHKERRQ(ierr);
2339       ierr = VecDestroy(&y);CHKERRQ(ierr); /* grant ownership */
2340     }
2341     if (u) {
2342       ierr = VecCopy(u,ts->vec_sol);CHKERRQ(ierr);
2343     }
2344   } else {
2345     if (u) {
2346       ierr = TSSetSolution(ts,u);CHKERRQ(ierr);
2347     }
2348   }
2349   ierr = TSSetUp(ts);CHKERRQ(ierr);
2350   /* reset time step and iteration counters */
2351   ts->steps = 0;
2352   ts->ksp_its = 0;
2353   ts->snes_its = 0;
2354   ts->num_snes_failures = 0;
2355   ts->reject = 0;
2356   ts->reason = TS_CONVERGED_ITERATING;
2357 
2358   if (ts->ops->solve) {         /* This private interface is transitional and should be removed when all implementations are updated. */
2359     ierr = (*ts->ops->solve)(ts);CHKERRQ(ierr);
2360     ierr = VecCopy(ts->vec_sol,u);CHKERRQ(ierr);
2361     ts->solvetime = ts->ptime;
2362   } else {
2363     /* steps the requested number of timesteps. */
2364     ierr = TSMonitor(ts,ts->steps,ts->ptime,ts->vec_sol);CHKERRQ(ierr);
2365     if (ts->steps >= ts->max_steps)
2366       ts->reason = TS_CONVERGED_ITS;
2367     else if (ts->ptime >= ts->max_time)
2368       ts->reason = TS_CONVERGED_TIME;
2369     while (!ts->reason) {
2370       ierr = TSStep(ts);CHKERRQ(ierr);
2371       ierr = TSPostStep(ts);CHKERRQ(ierr);
2372       ierr = TSMonitor(ts,ts->steps,ts->ptime,ts->vec_sol);CHKERRQ(ierr);
2373     }
2374     if (ts->exact_final_time == TS_EXACTFINALTIME_INTERPOLATE && ts->ptime > ts->max_time) {
2375       ierr = TSInterpolate(ts,ts->max_time,u);CHKERRQ(ierr);
2376       ts->solvetime = ts->max_time;
2377     } else {
2378       if (u) {ierr = VecCopy(ts->vec_sol,u);CHKERRQ(ierr);}
2379       ts->solvetime = ts->ptime;
2380     }
2381   }
2382   ierr = TSMonitor(ts,-1,ts->ptime,ts->vec_sol);CHKERRQ(ierr);
2383   ierr = PetscOptionsGetViewer(((PetscObject)ts)->comm,((PetscObject)ts)->prefix,"-ts_view",&viewer,&flg);CHKERRQ(ierr);
2384   if (flg && !PetscPreLoadingOn) {
2385     ierr = TSView(ts,viewer);CHKERRQ(ierr);
2386     ierr = PetscOptionsRestoreViewer(viewer);CHKERRQ(ierr);
2387   }
2388   PetscFunctionReturn(0);
2389 }
2390 
2391 #undef __FUNCT__
2392 #define __FUNCT__ "TSMonitor"
2393 /*@
2394    TSMonitor - Runs all user-provided monitor routines set using TSMonitorSet()
2395 
2396    Collective on TS
2397 
2398    Input Parameters:
2399 +  ts - time stepping context obtained from TSCreate()
2400 .  step - step number that has just completed
2401 .  ptime - model time of the state
2402 -  u - state at the current model time
2403 
2404    Notes:
2405    TSMonitor() is typically used within the time stepping implementations.
2406    Users might call this function when using the TSStep() interface instead of TSSolve().
2407 
2408    Level: advanced
2409 
2410 .keywords: TS, timestep
2411 @*/
2412 PetscErrorCode TSMonitor(TS ts,PetscInt step,PetscReal ptime,Vec u)
2413 {
2414   PetscErrorCode ierr;
2415   PetscInt       i,n = ts->numbermonitors;
2416 
2417   PetscFunctionBegin;
2418   for (i=0; i<n; i++) {
2419     ierr = (*ts->monitor[i])(ts,step,ptime,u,ts->monitorcontext[i]);CHKERRQ(ierr);
2420   }
2421   PetscFunctionReturn(0);
2422 }
2423 
2424 /* ------------------------------------------------------------------------*/
2425 struct _n_TSMonitorLGCtx {
2426   PetscDrawLG lg;
2427   PetscInt    howoften;  /* when > 0 uses step % howoften, when negative only final solution plotted */
2428   PetscInt    ksp_its,snes_its;
2429 };
2430 
2431 
2432 #undef __FUNCT__
2433 #define __FUNCT__ "TSMonitorLGCtxCreate"
2434 /*@C
2435    TSMonitorLGCtxCreate - Creates a line graph context for use with
2436    TS to monitor the solution process graphically in various ways
2437 
2438    Collective on TS
2439 
2440    Input Parameters:
2441 +  host - the X display to open, or null for the local machine
2442 .  label - the title to put in the title bar
2443 .  x, y - the screen coordinates of the upper left coordinate of the window
2444 .  m, n - the screen width and height in pixels
2445 -  howoften - if positive then determines the frequency of the plotting, if -1 then only at the final time
2446 
2447    Output Parameter:
2448 .  ctx - the context
2449 
2450    Options Database Key:
2451 +  -ts_monitor_lg_timestep - automatically sets line graph monitor
2452 .  -ts_monitor_lg_solution -
2453 .  -ts_monitor_lg_error -
2454 .  -ts_monitor_lg_ksp_iterations -
2455 .  -ts_monitor_lg_snes_iterations -
2456 -  -lg_indicate_data_points <true,false> - indicate the data points (at each time step) on the plot; default is true
2457 
2458    Notes:
2459    Use TSMonitorLGCtxDestroy() to destroy.
2460 
2461    Level: intermediate
2462 
2463 .keywords: TS, monitor, line graph, residual, seealso
2464 
2465 .seealso: TSMonitorLGTimeStep(), TSMonitorSet(), TSMonitorLGSolution(), TSMonitorLGError()
2466 
2467 @*/
2468 PetscErrorCode  TSMonitorLGCtxCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscInt howoften,TSMonitorLGCtx *ctx)
2469 {
2470   PetscDraw      win;
2471   PetscErrorCode ierr;
2472   PetscBool      flg = PETSC_TRUE;
2473 
2474   PetscFunctionBegin;
2475   ierr = PetscNew(struct _n_TSMonitorLGCtx,ctx);CHKERRQ(ierr);
2476   ierr = PetscDrawCreate(comm,host,label,x,y,m,n,&win);CHKERRQ(ierr);
2477   ierr = PetscDrawSetFromOptions(win);CHKERRQ(ierr);
2478   ierr = PetscDrawLGCreate(win,1,&(*ctx)->lg);CHKERRQ(ierr);
2479   ierr = PetscOptionsGetBool(PETSC_NULL,"-lg_indicate_data_points",&flg,PETSC_NULL);CHKERRQ(ierr);
2480   if (flg) {
2481     ierr = PetscDrawLGIndicateDataPoints((*ctx)->lg);CHKERRQ(ierr);
2482   }
2483   ierr = PetscLogObjectParent((*ctx)->lg,win);CHKERRQ(ierr);
2484   (*ctx)->howoften = howoften;
2485   PetscFunctionReturn(0);
2486 }
2487 
2488 #undef __FUNCT__
2489 #define __FUNCT__ "TSMonitorLGTimeStep"
2490 PetscErrorCode TSMonitorLGTimeStep(TS ts,PetscInt n,PetscReal ptime,Vec v,void *monctx)
2491 {
2492   TSMonitorLGCtx ctx = (TSMonitorLGCtx) monctx;
2493   PetscReal      x = ptime,y;
2494   PetscErrorCode ierr;
2495 
2496   PetscFunctionBegin;
2497   if (!n) {
2498     PetscDrawAxis  axis;
2499     ierr = PetscDrawLGGetAxis(ctx->lg,&axis);CHKERRQ(ierr);
2500     ierr = PetscDrawAxisSetLabels(axis,"Timestep as function of time","Time","Time step");CHKERRQ(ierr);
2501     ierr = PetscDrawLGReset(ctx->lg);CHKERRQ(ierr);
2502   }
2503   ierr = TSGetTimeStep(ts,&y);CHKERRQ(ierr);
2504   ierr = PetscDrawLGAddPoint(ctx->lg,&x,&y);CHKERRQ(ierr);
2505   if (((ctx->howoften > 0) && (!(n % ctx->howoften))) || ((ctx->howoften == -1) && (n == -1))){
2506     ierr = PetscDrawLGDraw(ctx->lg);CHKERRQ(ierr);
2507   }
2508   PetscFunctionReturn(0);
2509 }
2510 
2511 #undef __FUNCT__
2512 #define __FUNCT__ "TSMonitorLGCtxDestroy"
2513 /*@C
2514    TSMonitorLGCtxDestroy - Destroys a line graph context that was created
2515    with TSMonitorLGCtxCreate().
2516 
2517    Collective on TSMonitorLGCtx
2518 
2519    Input Parameter:
2520 .  ctx - the monitor context
2521 
2522    Level: intermediate
2523 
2524 .keywords: TS, monitor, line graph, destroy
2525 
2526 .seealso: TSMonitorLGCtxCreate(),  TSMonitorSet(), TSMonitorLGTimeStep();
2527 @*/
2528 PetscErrorCode  TSMonitorLGCtxDestroy(TSMonitorLGCtx *ctx)
2529 {
2530   PetscDraw      draw;
2531   PetscErrorCode ierr;
2532 
2533   PetscFunctionBegin;
2534   ierr = PetscDrawLGGetDraw((*ctx)->lg,&draw);CHKERRQ(ierr);
2535   ierr = PetscDrawDestroy(&draw);CHKERRQ(ierr);
2536   ierr = PetscDrawLGDestroy(&(*ctx)->lg);CHKERRQ(ierr);
2537   ierr = PetscFree(*ctx);CHKERRQ(ierr);
2538   PetscFunctionReturn(0);
2539 }
2540 
2541 #undef __FUNCT__
2542 #define __FUNCT__ "TSGetTime"
2543 /*@
2544    TSGetTime - Gets the time of the most recently completed step.
2545 
2546    Not Collective
2547 
2548    Input Parameter:
2549 .  ts - the TS context obtained from TSCreate()
2550 
2551    Output Parameter:
2552 .  t  - the current time
2553 
2554    Level: beginner
2555 
2556    Note:
2557    When called during time step evaluation (e.g. during residual evaluation or via hooks set using TSSetPreStep(),
2558    TSSetPreStage(), or TSSetPostStep()), the time is the time at the start of the step being evaluated.
2559 
2560 .seealso: TSSetInitialTimeStep(), TSGetTimeStep()
2561 
2562 .keywords: TS, get, time
2563 @*/
2564 PetscErrorCode  TSGetTime(TS ts,PetscReal* t)
2565 {
2566   PetscFunctionBegin;
2567   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2568   PetscValidRealPointer(t,2);
2569   *t = ts->ptime;
2570   PetscFunctionReturn(0);
2571 }
2572 
2573 #undef __FUNCT__
2574 #define __FUNCT__ "TSSetTime"
2575 /*@
2576    TSSetTime - Allows one to reset the time.
2577 
2578    Logically Collective on TS
2579 
2580    Input Parameters:
2581 +  ts - the TS context obtained from TSCreate()
2582 -  time - the time
2583 
2584    Level: intermediate
2585 
2586 .seealso: TSGetTime(), TSSetDuration()
2587 
2588 .keywords: TS, set, time
2589 @*/
2590 PetscErrorCode  TSSetTime(TS ts, PetscReal t)
2591 {
2592   PetscFunctionBegin;
2593   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2594   PetscValidLogicalCollectiveReal(ts,t,2);
2595   ts->ptime = t;
2596   PetscFunctionReturn(0);
2597 }
2598 
2599 #undef __FUNCT__
2600 #define __FUNCT__ "TSSetOptionsPrefix"
2601 /*@C
2602    TSSetOptionsPrefix - Sets the prefix used for searching for all
2603    TS options in the database.
2604 
2605    Logically Collective on TS
2606 
2607    Input Parameter:
2608 +  ts     - The TS context
2609 -  prefix - The prefix to prepend to all option names
2610 
2611    Notes:
2612    A hyphen (-) must NOT be given at the beginning of the prefix name.
2613    The first character of all runtime options is AUTOMATICALLY the
2614    hyphen.
2615 
2616    Level: advanced
2617 
2618 .keywords: TS, set, options, prefix, database
2619 
2620 .seealso: TSSetFromOptions()
2621 
2622 @*/
2623 PetscErrorCode  TSSetOptionsPrefix(TS ts,const char prefix[])
2624 {
2625   PetscErrorCode ierr;
2626   SNES           snes;
2627 
2628   PetscFunctionBegin;
2629   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2630   ierr = PetscObjectSetOptionsPrefix((PetscObject)ts,prefix);CHKERRQ(ierr);
2631   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
2632   ierr = SNESSetOptionsPrefix(snes,prefix);CHKERRQ(ierr);
2633   PetscFunctionReturn(0);
2634 }
2635 
2636 
2637 #undef __FUNCT__
2638 #define __FUNCT__ "TSAppendOptionsPrefix"
2639 /*@C
2640    TSAppendOptionsPrefix - Appends to the prefix used for searching for all
2641    TS options in the database.
2642 
2643    Logically Collective on TS
2644 
2645    Input Parameter:
2646 +  ts     - The TS context
2647 -  prefix - The prefix to prepend to all option names
2648 
2649    Notes:
2650    A hyphen (-) must NOT be given at the beginning of the prefix name.
2651    The first character of all runtime options is AUTOMATICALLY the
2652    hyphen.
2653 
2654    Level: advanced
2655 
2656 .keywords: TS, append, options, prefix, database
2657 
2658 .seealso: TSGetOptionsPrefix()
2659 
2660 @*/
2661 PetscErrorCode  TSAppendOptionsPrefix(TS ts,const char prefix[])
2662 {
2663   PetscErrorCode ierr;
2664   SNES           snes;
2665 
2666   PetscFunctionBegin;
2667   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2668   ierr = PetscObjectAppendOptionsPrefix((PetscObject)ts,prefix);CHKERRQ(ierr);
2669   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
2670   ierr = SNESAppendOptionsPrefix(snes,prefix);CHKERRQ(ierr);
2671   PetscFunctionReturn(0);
2672 }
2673 
2674 #undef __FUNCT__
2675 #define __FUNCT__ "TSGetOptionsPrefix"
2676 /*@C
2677    TSGetOptionsPrefix - Sets the prefix used for searching for all
2678    TS options in the database.
2679 
2680    Not Collective
2681 
2682    Input Parameter:
2683 .  ts - The TS context
2684 
2685    Output Parameter:
2686 .  prefix - A pointer to the prefix string used
2687 
2688    Notes: On the fortran side, the user should pass in a string 'prifix' of
2689    sufficient length to hold the prefix.
2690 
2691    Level: intermediate
2692 
2693 .keywords: TS, get, options, prefix, database
2694 
2695 .seealso: TSAppendOptionsPrefix()
2696 @*/
2697 PetscErrorCode  TSGetOptionsPrefix(TS ts,const char *prefix[])
2698 {
2699   PetscErrorCode ierr;
2700 
2701   PetscFunctionBegin;
2702   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2703   PetscValidPointer(prefix,2);
2704   ierr = PetscObjectGetOptionsPrefix((PetscObject)ts,prefix);CHKERRQ(ierr);
2705   PetscFunctionReturn(0);
2706 }
2707 
2708 #undef __FUNCT__
2709 #define __FUNCT__ "TSGetRHSJacobian"
2710 /*@C
2711    TSGetRHSJacobian - Returns the Jacobian J at the present timestep.
2712 
2713    Not Collective, but parallel objects are returned if TS is parallel
2714 
2715    Input Parameter:
2716 .  ts  - The TS context obtained from TSCreate()
2717 
2718    Output Parameters:
2719 +  J   - The Jacobian J of F, where U_t = G(U,t)
2720 .  M   - The preconditioner matrix, usually the same as J
2721 .  func - Function to compute the Jacobian of the RHS
2722 -  ctx - User-defined context for Jacobian evaluation routine
2723 
2724    Notes: You can pass in PETSC_NULL for any return argument you do not need.
2725 
2726    Level: intermediate
2727 
2728 .seealso: TSGetTimeStep(), TSGetMatrices(), TSGetTime(), TSGetTimeStepNumber()
2729 
2730 .keywords: TS, timestep, get, matrix, Jacobian
2731 @*/
2732 PetscErrorCode  TSGetRHSJacobian(TS ts,Mat *J,Mat *M,TSRHSJacobian *func,void **ctx)
2733 {
2734   PetscErrorCode ierr;
2735   SNES           snes;
2736   DM             dm;
2737 
2738   PetscFunctionBegin;
2739   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
2740   ierr = SNESGetJacobian(snes,J,M,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
2741   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
2742   ierr = DMTSGetRHSJacobian(dm,func,ctx);CHKERRQ(ierr);
2743   PetscFunctionReturn(0);
2744 }
2745 
2746 #undef __FUNCT__
2747 #define __FUNCT__ "TSGetIJacobian"
2748 /*@C
2749    TSGetIJacobian - Returns the implicit Jacobian at the present timestep.
2750 
2751    Not Collective, but parallel objects are returned if TS is parallel
2752 
2753    Input Parameter:
2754 .  ts  - The TS context obtained from TSCreate()
2755 
2756    Output Parameters:
2757 +  A   - The Jacobian of F(t,U,U_t)
2758 .  B   - The preconditioner matrix, often the same as A
2759 .  f   - The function to compute the matrices
2760 - ctx - User-defined context for Jacobian evaluation routine
2761 
2762    Notes: You can pass in PETSC_NULL for any return argument you do not need.
2763 
2764    Level: advanced
2765 
2766 .seealso: TSGetTimeStep(), TSGetRHSJacobian(), TSGetMatrices(), TSGetTime(), TSGetTimeStepNumber()
2767 
2768 .keywords: TS, timestep, get, matrix, Jacobian
2769 @*/
2770 PetscErrorCode  TSGetIJacobian(TS ts,Mat *A,Mat *B,TSIJacobian *f,void **ctx)
2771 {
2772   PetscErrorCode ierr;
2773   SNES           snes;
2774   DM             dm;
2775 
2776   PetscFunctionBegin;
2777   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
2778   ierr = SNESSetUpMatrices(snes);CHKERRQ(ierr);
2779   ierr = SNESGetJacobian(snes,A,B,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
2780   ierr = TSGetDM(ts,&dm);CHKERRQ(ierr);
2781   ierr = DMTSGetIJacobian(dm,f,ctx);CHKERRQ(ierr);
2782   PetscFunctionReturn(0);
2783 }
2784 
2785 struct _n_TSMonitorDrawCtx {
2786   PetscViewer viewer;
2787   Vec         initialsolution;
2788   PetscBool   showinitial;
2789   PetscInt    howoften;  /* when > 0 uses step % howoften, when negative only final solution plotted */
2790 };
2791 
2792 #undef __FUNCT__
2793 #define __FUNCT__ "TSMonitorDrawSolution"
2794 /*@C
2795    TSMonitorDrawSolution - Monitors progress of the TS solvers by calling
2796    VecView() for the solution at each timestep
2797 
2798    Collective on TS
2799 
2800    Input Parameters:
2801 +  ts - the TS context
2802 .  step - current time-step
2803 .  ptime - current time
2804 -  dummy - either a viewer or PETSC_NULL
2805 
2806    Options Database:
2807 .   -ts_monitor_draw_solution_initial - show initial solution as well as current solution
2808 
2809    Notes: the initial solution and current solution are not displayed with a common axis scaling so generally the option -ts_monitor_draw_solution_initial
2810        will look bad
2811 
2812    Level: intermediate
2813 
2814 .keywords: TS,  vector, monitor, view
2815 
2816 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView()
2817 @*/
2818 PetscErrorCode  TSMonitorDrawSolution(TS ts,PetscInt step,PetscReal ptime,Vec u,void *dummy)
2819 {
2820   PetscErrorCode   ierr;
2821   TSMonitorDrawCtx ictx = (TSMonitorDrawCtx)dummy;
2822 
2823   PetscFunctionBegin;
2824   if (!step && ictx->showinitial) {
2825     if (!ictx->initialsolution) {
2826       ierr = VecDuplicate(u,&ictx->initialsolution);CHKERRQ(ierr);
2827     }
2828     ierr = VecCopy(u,ictx->initialsolution);CHKERRQ(ierr);
2829   }
2830   if (!(((ictx->howoften > 0) && (!(step % ictx->howoften)) && (step > -1)) || ((ictx->howoften == -1) && (step == -1)))) PetscFunctionReturn(0);
2831 
2832   if (ictx->showinitial) {
2833     PetscReal pause;
2834     ierr = PetscViewerDrawGetPause(ictx->viewer,&pause);CHKERRQ(ierr);
2835     ierr = PetscViewerDrawSetPause(ictx->viewer,0.0);CHKERRQ(ierr);
2836     ierr = VecView(ictx->initialsolution,ictx->viewer);CHKERRQ(ierr);
2837     ierr = PetscViewerDrawSetPause(ictx->viewer,pause);CHKERRQ(ierr);
2838     ierr = PetscViewerDrawSetHold(ictx->viewer,PETSC_TRUE);CHKERRQ(ierr);
2839   }
2840   ierr = VecView(u,ictx->viewer);CHKERRQ(ierr);
2841   if (ictx->showinitial) {
2842     ierr = PetscViewerDrawSetHold(ictx->viewer,PETSC_FALSE);CHKERRQ(ierr);
2843   }
2844   PetscFunctionReturn(0);
2845 }
2846 
2847 
2848 #undef __FUNCT__
2849 #define __FUNCT__ "TSMonitorDrawCtxDestroy"
2850 /*@C
2851    TSMonitorDrawCtxDestroy - Destroys the monitor context for TSMonitorDrawSolution()
2852 
2853    Collective on TS
2854 
2855    Input Parameters:
2856 .    ctx - the monitor context
2857 
2858    Level: intermediate
2859 
2860 .keywords: TS,  vector, monitor, view
2861 
2862 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView(), TSMonitorDrawSolution(), TSMonitorDrawError()
2863 @*/
2864 PetscErrorCode  TSMonitorDrawCtxDestroy(TSMonitorDrawCtx *ictx)
2865 {
2866   PetscErrorCode       ierr;
2867 
2868   PetscFunctionBegin;
2869   ierr = PetscViewerDestroy(&(*ictx)->viewer);CHKERRQ(ierr);
2870   ierr = VecDestroy(&(*ictx)->initialsolution);CHKERRQ(ierr);
2871   ierr = PetscFree(*ictx);CHKERRQ(ierr);
2872   PetscFunctionReturn(0);
2873 }
2874 
2875 #undef __FUNCT__
2876 #define __FUNCT__ "TSMonitorDrawCtxCreate"
2877 /*@C
2878    TSMonitorDrawCtxCreate - Creates the monitor context for TSMonitorDrawCtx
2879 
2880    Collective on TS
2881 
2882    Input Parameter:
2883 .    ts - time-step context
2884 
2885    Output Patameter:
2886 .    ctx - the monitor context
2887 
2888    Options Database:
2889 .   -ts_monitor_draw_solution_initial - show initial solution as well as current solution
2890 
2891    Level: intermediate
2892 
2893 .keywords: TS,  vector, monitor, view
2894 
2895 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView(), TSMonitorDrawCtx()
2896 @*/
2897 PetscErrorCode  TSMonitorDrawCtxCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscInt howoften,TSMonitorDrawCtx *ctx)
2898 {
2899   PetscErrorCode   ierr;
2900 
2901   PetscFunctionBegin;
2902   ierr = PetscNew(struct _n_TSMonitorDrawCtx,ctx);CHKERRQ(ierr);
2903   ierr = PetscViewerDrawOpen(comm,host,label,x,y,m,n,&(*ctx)->viewer);CHKERRQ(ierr);
2904   (*ctx)->showinitial = PETSC_FALSE;
2905   (*ctx)->howoften    = howoften;
2906   ierr = PetscOptionsGetBool(PETSC_NULL,"-ts_monitor_draw_solution_initial",&(*ctx)->showinitial,PETSC_NULL);CHKERRQ(ierr);
2907   PetscFunctionReturn(0);
2908 }
2909 
2910 #undef __FUNCT__
2911 #define __FUNCT__ "TSMonitorDrawError"
2912 /*@C
2913    TSMonitorDrawError - Monitors progress of the TS solvers by calling
2914    VecView() for the error at each timestep
2915 
2916    Collective on TS
2917 
2918    Input Parameters:
2919 +  ts - the TS context
2920 .  step - current time-step
2921 .  ptime - current time
2922 -  dummy - either a viewer or PETSC_NULL
2923 
2924    Level: intermediate
2925 
2926 .keywords: TS,  vector, monitor, view
2927 
2928 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView()
2929 @*/
2930 PetscErrorCode  TSMonitorDrawError(TS ts,PetscInt step,PetscReal ptime,Vec u,void *dummy)
2931 {
2932   PetscErrorCode   ierr;
2933   TSMonitorDrawCtx ctx = (TSMonitorDrawCtx)dummy;
2934   PetscViewer      viewer = ctx->viewer;
2935   Vec              work;
2936 
2937   PetscFunctionBegin;
2938   if (!(((ctx->howoften > 0) && (!(step % ctx->howoften)) && (step > -1)) || ((ctx->howoften == -1) && (step == -1)))) PetscFunctionReturn(0);
2939   ierr = VecDuplicate(u,&work);CHKERRQ(ierr);
2940   ierr = TSComputeSolutionFunction(ts,ptime,work);CHKERRQ(ierr);
2941   ierr = VecAXPY(work,-1.0,u);CHKERRQ(ierr);
2942   ierr = VecView(work,viewer);CHKERRQ(ierr);
2943   ierr = VecDestroy(&work);CHKERRQ(ierr);
2944   PetscFunctionReturn(0);
2945 }
2946 
2947 #include <petsc-private/dmimpl.h>
2948 #undef __FUNCT__
2949 #define __FUNCT__ "TSSetDM"
2950 /*@
2951    TSSetDM - Sets the DM that may be used by some preconditioners
2952 
2953    Logically Collective on TS and DM
2954 
2955    Input Parameters:
2956 +  ts - the preconditioner context
2957 -  dm - the dm
2958 
2959    Level: intermediate
2960 
2961 
2962 .seealso: TSGetDM(), SNESSetDM(), SNESGetDM()
2963 @*/
2964 PetscErrorCode  TSSetDM(TS ts,DM dm)
2965 {
2966   PetscErrorCode ierr;
2967   SNES           snes;
2968   DMTS           tsdm;
2969 
2970   PetscFunctionBegin;
2971   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
2972   ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);
2973   if (ts->dm) {               /* Move the DMTS context over to the new DM unless the new DM already has one */
2974     if (ts->dm->dmts && !dm->dmts) {
2975       ierr = DMCopyDMTS(ts->dm,dm);CHKERRQ(ierr);
2976       ierr = DMGetDMTS(ts->dm,&tsdm);CHKERRQ(ierr);
2977       if (tsdm->originaldm == ts->dm) { /* Grant write privileges to the replacement DM */
2978         tsdm->originaldm = dm;
2979       }
2980     }
2981     ierr = DMDestroy(&ts->dm);CHKERRQ(ierr);
2982   }
2983   ts->dm = dm;
2984   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
2985   ierr = SNESSetDM(snes,dm);CHKERRQ(ierr);
2986   PetscFunctionReturn(0);
2987 }
2988 
2989 #undef __FUNCT__
2990 #define __FUNCT__ "TSGetDM"
2991 /*@
2992    TSGetDM - Gets the DM that may be used by some preconditioners
2993 
2994    Not Collective
2995 
2996    Input Parameter:
2997 . ts - the preconditioner context
2998 
2999    Output Parameter:
3000 .  dm - the dm
3001 
3002    Level: intermediate
3003 
3004 
3005 .seealso: TSSetDM(), SNESSetDM(), SNESGetDM()
3006 @*/
3007 PetscErrorCode  TSGetDM(TS ts,DM *dm)
3008 {
3009   PetscErrorCode ierr;
3010 
3011   PetscFunctionBegin;
3012   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3013   if (!ts->dm) {
3014     ierr = DMShellCreate(((PetscObject)ts)->comm,&ts->dm);CHKERRQ(ierr);
3015     if (ts->snes) {ierr = SNESSetDM(ts->snes,ts->dm);CHKERRQ(ierr);}
3016   }
3017   *dm = ts->dm;
3018   PetscFunctionReturn(0);
3019 }
3020 
3021 #undef __FUNCT__
3022 #define __FUNCT__ "SNESTSFormFunction"
3023 /*@
3024    SNESTSFormFunction - Function to evaluate nonlinear residual
3025 
3026    Logically Collective on SNES
3027 
3028    Input Parameter:
3029 + snes - nonlinear solver
3030 . U - the current state at which to evaluate the residual
3031 - ctx - user context, must be a TS
3032 
3033    Output Parameter:
3034 . F - the nonlinear residual
3035 
3036    Notes:
3037    This function is not normally called by users and is automatically registered with the SNES used by TS.
3038    It is most frequently passed to MatFDColoringSetFunction().
3039 
3040    Level: advanced
3041 
3042 .seealso: SNESSetFunction(), MatFDColoringSetFunction()
3043 @*/
3044 PetscErrorCode  SNESTSFormFunction(SNES snes,Vec U,Vec F,void *ctx)
3045 {
3046   TS             ts = (TS)ctx;
3047   PetscErrorCode ierr;
3048 
3049   PetscFunctionBegin;
3050   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3051   PetscValidHeaderSpecific(U,VEC_CLASSID,2);
3052   PetscValidHeaderSpecific(F,VEC_CLASSID,3);
3053   PetscValidHeaderSpecific(ts,TS_CLASSID,4);
3054   ierr = (ts->ops->snesfunction)(snes,U,F,ts);CHKERRQ(ierr);
3055   PetscFunctionReturn(0);
3056 }
3057 
3058 #undef __FUNCT__
3059 #define __FUNCT__ "SNESTSFormJacobian"
3060 /*@
3061    SNESTSFormJacobian - Function to evaluate the Jacobian
3062 
3063    Collective on SNES
3064 
3065    Input Parameter:
3066 + snes - nonlinear solver
3067 . U - the current state at which to evaluate the residual
3068 - ctx - user context, must be a TS
3069 
3070    Output Parameter:
3071 + A - the Jacobian
3072 . B - the preconditioning matrix (may be the same as A)
3073 - flag - indicates any structure change in the matrix
3074 
3075    Notes:
3076    This function is not normally called by users and is automatically registered with the SNES used by TS.
3077 
3078    Level: developer
3079 
3080 .seealso: SNESSetJacobian()
3081 @*/
3082 PetscErrorCode  SNESTSFormJacobian(SNES snes,Vec U,Mat *A,Mat *B,MatStructure *flag,void *ctx)
3083 {
3084   TS             ts = (TS)ctx;
3085   PetscErrorCode ierr;
3086 
3087   PetscFunctionBegin;
3088   PetscValidHeaderSpecific(snes,SNES_CLASSID,1);
3089   PetscValidHeaderSpecific(U,VEC_CLASSID,2);
3090   PetscValidPointer(A,3);
3091   PetscValidHeaderSpecific(*A,MAT_CLASSID,3);
3092   PetscValidPointer(B,4);
3093   PetscValidHeaderSpecific(*B,MAT_CLASSID,4);
3094   PetscValidPointer(flag,5);
3095   PetscValidHeaderSpecific(ts,TS_CLASSID,6);
3096   ierr = (ts->ops->snesjacobian)(snes,U,A,B,flag,ts);CHKERRQ(ierr);
3097   PetscFunctionReturn(0);
3098 }
3099 
3100 #undef __FUNCT__
3101 #define __FUNCT__ "TSComputeRHSFunctionLinear"
3102 /*@C
3103    TSComputeRHSFunctionLinear - Evaluate the right hand side via the user-provided Jacobian, for linear problems only
3104 
3105    Collective on TS
3106 
3107    Input Arguments:
3108 +  ts - time stepping context
3109 .  t - time at which to evaluate
3110 .  U - state at which to evaluate
3111 -  ctx - context
3112 
3113    Output Arguments:
3114 .  F - right hand side
3115 
3116    Level: intermediate
3117 
3118    Notes:
3119    This function is intended to be passed to TSSetRHSFunction() to evaluate the right hand side for linear problems.
3120    The matrix (and optionally the evaluation context) should be passed to TSSetRHSJacobian().
3121 
3122 .seealso: TSSetRHSFunction(), TSSetRHSJacobian(), TSComputeRHSJacobianConstant()
3123 @*/
3124 PetscErrorCode TSComputeRHSFunctionLinear(TS ts,PetscReal t,Vec U,Vec F,void *ctx)
3125 {
3126   PetscErrorCode ierr;
3127   Mat            Arhs,Brhs;
3128   MatStructure   flg2;
3129 
3130   PetscFunctionBegin;
3131   ierr = TSGetRHSMats_Private(ts,&Arhs,&Brhs);CHKERRQ(ierr);
3132   ierr = TSComputeRHSJacobian(ts,t,U,&Arhs,&Brhs,&flg2);CHKERRQ(ierr);
3133   ierr = MatMult(Arhs,U,F);CHKERRQ(ierr);
3134   PetscFunctionReturn(0);
3135 }
3136 
3137 #undef __FUNCT__
3138 #define __FUNCT__ "TSComputeRHSJacobianConstant"
3139 /*@C
3140    TSComputeRHSJacobianConstant - Reuses a Jacobian that is time-independent.
3141 
3142    Collective on TS
3143 
3144    Input Arguments:
3145 +  ts - time stepping context
3146 .  t - time at which to evaluate
3147 .  U - state at which to evaluate
3148 -  ctx - context
3149 
3150    Output Arguments:
3151 +  A - pointer to operator
3152 .  B - pointer to preconditioning matrix
3153 -  flg - matrix structure flag
3154 
3155    Level: intermediate
3156 
3157    Notes:
3158    This function is intended to be passed to TSSetRHSJacobian() to evaluate the Jacobian for linear time-independent problems.
3159 
3160 .seealso: TSSetRHSFunction(), TSSetRHSJacobian(), TSComputeRHSFunctionLinear()
3161 @*/
3162 PetscErrorCode TSComputeRHSJacobianConstant(TS ts,PetscReal t,Vec U,Mat *A,Mat *B,MatStructure *flg,void *ctx)
3163 {
3164   PetscFunctionBegin;
3165   *flg = SAME_PRECONDITIONER;
3166   PetscFunctionReturn(0);
3167 }
3168 
3169 #undef __FUNCT__
3170 #define __FUNCT__ "TSComputeIFunctionLinear"
3171 /*@C
3172    TSComputeIFunctionLinear - Evaluate the left hand side via the user-provided Jacobian, for linear problems only
3173 
3174    Collective on TS
3175 
3176    Input Arguments:
3177 +  ts - time stepping context
3178 .  t - time at which to evaluate
3179 .  U - state at which to evaluate
3180 .  Udot - time derivative of state vector
3181 -  ctx - context
3182 
3183    Output Arguments:
3184 .  F - left hand side
3185 
3186    Level: intermediate
3187 
3188    Notes:
3189    The assumption here is that the left hand side is of the form A*Udot (and not A*Udot + B*U). For other cases, the
3190    user is required to write their own TSComputeIFunction.
3191    This function is intended to be passed to TSSetIFunction() to evaluate the left hand side for linear problems.
3192    The matrix (and optionally the evaluation context) should be passed to TSSetIJacobian().
3193 
3194 .seealso: TSSetIFunction(), TSSetIJacobian(), TSComputeIJacobianConstant()
3195 @*/
3196 PetscErrorCode TSComputeIFunctionLinear(TS ts,PetscReal t,Vec U,Vec Udot,Vec F,void *ctx)
3197 {
3198   PetscErrorCode ierr;
3199   Mat            A,B;
3200   MatStructure   flg2;
3201 
3202   PetscFunctionBegin;
3203   ierr = TSGetIJacobian(ts,&A,&B,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
3204   ierr = TSComputeIJacobian(ts,t,U,Udot,1.0,&A,&B,&flg2,PETSC_TRUE);CHKERRQ(ierr);
3205   ierr = MatMult(A,Udot,F);CHKERRQ(ierr);
3206   PetscFunctionReturn(0);
3207 }
3208 
3209 #undef __FUNCT__
3210 #define __FUNCT__ "TSComputeIJacobianConstant"
3211 /*@C
3212    TSComputeIJacobianConstant - Reuses a Jacobian that is time-independent.
3213 
3214    Collective on TS
3215 
3216    Input Arguments:
3217 +  ts - time stepping context
3218 .  t - time at which to evaluate
3219 .  U - state at which to evaluate
3220 .  Udot - time derivative of state vector
3221 .  shift - shift to apply
3222 -  ctx - context
3223 
3224    Output Arguments:
3225 +  A - pointer to operator
3226 .  B - pointer to preconditioning matrix
3227 -  flg - matrix structure flag
3228 
3229    Level: intermediate
3230 
3231    Notes:
3232    This function is intended to be passed to TSSetIJacobian() to evaluate the Jacobian for linear time-independent problems.
3233 
3234 .seealso: TSSetIFunction(), TSSetIJacobian(), TSComputeIFunctionLinear()
3235 @*/
3236 PetscErrorCode TSComputeIJacobianConstant(TS ts,PetscReal t,Vec U,Vec Udot,PetscReal shift,Mat *A,Mat *B,MatStructure *flg,void *ctx)
3237 {
3238   PetscFunctionBegin;
3239   *flg = SAME_PRECONDITIONER;
3240   PetscFunctionReturn(0);
3241 }
3242 
3243 #undef __FUNCT__
3244 #define __FUNCT__ "TSGetConvergedReason"
3245 /*@
3246    TSGetConvergedReason - Gets the reason the TS iteration was stopped.
3247 
3248    Not Collective
3249 
3250    Input Parameter:
3251 .  ts - the TS context
3252 
3253    Output Parameter:
3254 .  reason - negative value indicates diverged, positive value converged, see TSConvergedReason or the
3255             manual pages for the individual convergence tests for complete lists
3256 
3257    Level: beginner
3258 
3259    Notes:
3260    Can only be called after the call to TSSolve() is complete.
3261 
3262 .keywords: TS, nonlinear, set, convergence, test
3263 
3264 .seealso: TSSetConvergenceTest(), TSConvergedReason
3265 @*/
3266 PetscErrorCode  TSGetConvergedReason(TS ts,TSConvergedReason *reason)
3267 {
3268   PetscFunctionBegin;
3269   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3270   PetscValidPointer(reason,2);
3271   *reason = ts->reason;
3272   PetscFunctionReturn(0);
3273 }
3274 
3275 #undef __FUNCT__
3276 #define __FUNCT__ "TSSetConvergedReason"
3277 /*@
3278    TSSetConvergedReason - Sets the reason for handling the convergence of TSSolve.
3279 
3280    Not Collective
3281 
3282    Input Parameter:
3283 +  ts - the TS context
3284 .  reason - negative value indicates diverged, positive value converged, see TSConvergedReason or the
3285             manual pages for the individual convergence tests for complete lists
3286 
3287    Level: advanced
3288 
3289    Notes:
3290    Can only be called during TSSolve() is active.
3291 
3292 .keywords: TS, nonlinear, set, convergence, test
3293 
3294 .seealso: TSConvergedReason
3295 @*/
3296 PetscErrorCode  TSSetConvergedReason(TS ts,TSConvergedReason reason)
3297 {
3298   PetscFunctionBegin;
3299   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3300   ts->reason = reason;
3301   PetscFunctionReturn(0);
3302 }
3303 
3304 #undef __FUNCT__
3305 #define __FUNCT__ "TSGetSolveTime"
3306 /*@
3307    TSGetSolveTime - Gets the time after a call to TSSolve()
3308 
3309    Not Collective
3310 
3311    Input Parameter:
3312 .  ts - the TS context
3313 
3314    Output Parameter:
3315 .  ftime - the final time. This time should correspond to the final time set with TSSetDuration()
3316 
3317    Level: beginner
3318 
3319    Notes:
3320    Can only be called after the call to TSSolve() is complete.
3321 
3322 .keywords: TS, nonlinear, set, convergence, test
3323 
3324 .seealso: TSSetConvergenceTest(), TSConvergedReason
3325 @*/
3326 PetscErrorCode  TSGetSolveTime(TS ts,PetscReal *ftime)
3327 {
3328   PetscFunctionBegin;
3329   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3330   PetscValidPointer(ftime,2);
3331   *ftime = ts->solvetime;
3332   PetscFunctionReturn(0);
3333 }
3334 
3335 #undef __FUNCT__
3336 #define __FUNCT__ "TSGetSNESIterations"
3337 /*@
3338    TSGetSNESIterations - Gets the total number of nonlinear iterations
3339    used by the time integrator.
3340 
3341    Not Collective
3342 
3343    Input Parameter:
3344 .  ts - TS context
3345 
3346    Output Parameter:
3347 .  nits - number of nonlinear iterations
3348 
3349    Notes:
3350    This counter is reset to zero for each successive call to TSSolve().
3351 
3352    Level: intermediate
3353 
3354 .keywords: TS, get, number, nonlinear, iterations
3355 
3356 .seealso:  TSGetKSPIterations()
3357 @*/
3358 PetscErrorCode TSGetSNESIterations(TS ts,PetscInt *nits)
3359 {
3360   PetscFunctionBegin;
3361   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3362   PetscValidIntPointer(nits,2);
3363   *nits = ts->snes_its;
3364   PetscFunctionReturn(0);
3365 }
3366 
3367 #undef __FUNCT__
3368 #define __FUNCT__ "TSGetKSPIterations"
3369 /*@
3370    TSGetKSPIterations - Gets the total number of linear iterations
3371    used by the time integrator.
3372 
3373    Not Collective
3374 
3375    Input Parameter:
3376 .  ts - TS context
3377 
3378    Output Parameter:
3379 .  lits - number of linear iterations
3380 
3381    Notes:
3382    This counter is reset to zero for each successive call to TSSolve().
3383 
3384    Level: intermediate
3385 
3386 .keywords: TS, get, number, linear, iterations
3387 
3388 .seealso:  TSGetSNESIterations(), SNESGetKSPIterations()
3389 @*/
3390 PetscErrorCode TSGetKSPIterations(TS ts,PetscInt *lits)
3391 {
3392   PetscFunctionBegin;
3393   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3394   PetscValidIntPointer(lits,2);
3395   *lits = ts->ksp_its;
3396   PetscFunctionReturn(0);
3397 }
3398 
3399 #undef __FUNCT__
3400 #define __FUNCT__ "TSGetStepRejections"
3401 /*@
3402    TSGetStepRejections - Gets the total number of rejected steps.
3403 
3404    Not Collective
3405 
3406    Input Parameter:
3407 .  ts - TS context
3408 
3409    Output Parameter:
3410 .  rejects - number of steps rejected
3411 
3412    Notes:
3413    This counter is reset to zero for each successive call to TSSolve().
3414 
3415    Level: intermediate
3416 
3417 .keywords: TS, get, number
3418 
3419 .seealso:  TSGetSNESIterations(), TSGetKSPIterations(), TSSetMaxStepRejections(), TSGetSNESFailures(), TSSetMaxSNESFailures(), TSSetErrorIfStepFails()
3420 @*/
3421 PetscErrorCode TSGetStepRejections(TS ts,PetscInt *rejects)
3422 {
3423   PetscFunctionBegin;
3424   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3425   PetscValidIntPointer(rejects,2);
3426   *rejects = ts->reject;
3427   PetscFunctionReturn(0);
3428 }
3429 
3430 #undef __FUNCT__
3431 #define __FUNCT__ "TSGetSNESFailures"
3432 /*@
3433    TSGetSNESFailures - Gets the total number of failed SNES solves
3434 
3435    Not Collective
3436 
3437    Input Parameter:
3438 .  ts - TS context
3439 
3440    Output Parameter:
3441 .  fails - number of failed nonlinear solves
3442 
3443    Notes:
3444    This counter is reset to zero for each successive call to TSSolve().
3445 
3446    Level: intermediate
3447 
3448 .keywords: TS, get, number
3449 
3450 .seealso:  TSGetSNESIterations(), TSGetKSPIterations(), TSSetMaxStepRejections(), TSGetStepRejections(), TSSetMaxSNESFailures()
3451 @*/
3452 PetscErrorCode TSGetSNESFailures(TS ts,PetscInt *fails)
3453 {
3454   PetscFunctionBegin;
3455   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3456   PetscValidIntPointer(fails,2);
3457   *fails = ts->num_snes_failures;
3458   PetscFunctionReturn(0);
3459 }
3460 
3461 #undef __FUNCT__
3462 #define __FUNCT__ "TSSetMaxStepRejections"
3463 /*@
3464    TSSetMaxStepRejections - Sets the maximum number of step rejections before a step fails
3465 
3466    Not Collective
3467 
3468    Input Parameter:
3469 +  ts - TS context
3470 -  rejects - maximum number of rejected steps, pass -1 for unlimited
3471 
3472    Notes:
3473    The counter is reset to zero for each step
3474 
3475    Options Database Key:
3476  .  -ts_max_reject - Maximum number of step rejections before a step fails
3477 
3478    Level: intermediate
3479 
3480 .keywords: TS, set, maximum, number
3481 
3482 .seealso:  TSGetSNESIterations(), TSGetKSPIterations(), TSSetMaxSNESFailures(), TSGetStepRejections(), TSGetSNESFailures(), TSSetErrorIfStepFails(), TSGetConvergedReason()
3483 @*/
3484 PetscErrorCode TSSetMaxStepRejections(TS ts,PetscInt rejects)
3485 {
3486   PetscFunctionBegin;
3487   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3488   ts->max_reject = rejects;
3489   PetscFunctionReturn(0);
3490 }
3491 
3492 #undef __FUNCT__
3493 #define __FUNCT__ "TSSetMaxSNESFailures"
3494 /*@
3495    TSSetMaxSNESFailures - Sets the maximum number of failed SNES solves
3496 
3497    Not Collective
3498 
3499    Input Parameter:
3500 +  ts - TS context
3501 -  fails - maximum number of failed nonlinear solves, pass -1 for unlimited
3502 
3503    Notes:
3504    The counter is reset to zero for each successive call to TSSolve().
3505 
3506    Options Database Key:
3507  .  -ts_max_snes_failures - Maximum number of nonlinear solve failures
3508 
3509    Level: intermediate
3510 
3511 .keywords: TS, set, maximum, number
3512 
3513 .seealso:  TSGetSNESIterations(), TSGetKSPIterations(), TSSetMaxStepRejections(), TSGetStepRejections(), TSGetSNESFailures(), SNESGetConvergedReason(), TSGetConvergedReason()
3514 @*/
3515 PetscErrorCode TSSetMaxSNESFailures(TS ts,PetscInt fails)
3516 {
3517   PetscFunctionBegin;
3518   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3519   ts->max_snes_failures = fails;
3520   PetscFunctionReturn(0);
3521 }
3522 
3523 #undef __FUNCT__
3524 #define __FUNCT__ "TSSetErrorIfStepFails()"
3525 /*@
3526    TSSetErrorIfStepFails - Error if no step succeeds
3527 
3528    Not Collective
3529 
3530    Input Parameter:
3531 +  ts - TS context
3532 -  err - PETSC_TRUE to error if no step succeeds, PETSC_FALSE to return without failure
3533 
3534    Options Database Key:
3535  .  -ts_error_if_step_fails - Error if no step succeeds
3536 
3537    Level: intermediate
3538 
3539 .keywords: TS, set, error
3540 
3541 .seealso:  TSGetSNESIterations(), TSGetKSPIterations(), TSSetMaxStepRejections(), TSGetStepRejections(), TSGetSNESFailures(), TSSetErrorIfStepFails(), TSGetConvergedReason()
3542 @*/
3543 PetscErrorCode TSSetErrorIfStepFails(TS ts,PetscBool err)
3544 {
3545   PetscFunctionBegin;
3546   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3547   ts->errorifstepfailed = err;
3548   PetscFunctionReturn(0);
3549 }
3550 
3551 #undef __FUNCT__
3552 #define __FUNCT__ "TSMonitorSolutionBinary"
3553 /*@C
3554    TSMonitorSolutionBinary - Monitors progress of the TS solvers by VecView() for the solution at each timestep. Normally the viewer is a binary file
3555 
3556    Collective on TS
3557 
3558    Input Parameters:
3559 +  ts - the TS context
3560 .  step - current time-step
3561 .  ptime - current time
3562 .  u - current state
3563 -  viewer - binary viewer
3564 
3565    Level: intermediate
3566 
3567 .keywords: TS,  vector, monitor, view
3568 
3569 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView()
3570 @*/
3571 PetscErrorCode  TSMonitorSolutionBinary(TS ts,PetscInt step,PetscReal ptime,Vec u,void *viewer)
3572 {
3573   PetscErrorCode ierr;
3574   PetscViewer    v = (PetscViewer)viewer;
3575 
3576   PetscFunctionBegin;
3577   ierr = VecView(u,v);CHKERRQ(ierr);
3578   PetscFunctionReturn(0);
3579 }
3580 
3581 #undef __FUNCT__
3582 #define __FUNCT__ "TSMonitorSolutionVTK"
3583 /*@C
3584    TSMonitorSolutionVTK - Monitors progress of the TS solvers by VecView() for the solution at each timestep.
3585 
3586    Collective on TS
3587 
3588    Input Parameters:
3589 +  ts - the TS context
3590 .  step - current time-step
3591 .  ptime - current time
3592 .  u - current state
3593 -  filenametemplate - string containing a format specifier for the integer time step (e.g. %03D)
3594 
3595    Level: intermediate
3596 
3597    Notes:
3598    The VTK format does not allow writing multiple time steps in the same file, therefore a different file will be written for each time step.
3599    These are named according to the file name template.
3600 
3601    This function is normally passed as an argument to TSMonitorSet() along with TSMonitorSolutionVTKDestroy().
3602 
3603 .keywords: TS,  vector, monitor, view
3604 
3605 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView()
3606 @*/
3607 PetscErrorCode TSMonitorSolutionVTK(TS ts,PetscInt step,PetscReal ptime,Vec u,void *filenametemplate)
3608 {
3609   PetscErrorCode ierr;
3610   char           filename[PETSC_MAX_PATH_LEN];
3611   PetscViewer    viewer;
3612 
3613   PetscFunctionBegin;
3614   ierr = PetscSNPrintf(filename,sizeof(filename),(const char*)filenametemplate,step);CHKERRQ(ierr);
3615   ierr = PetscViewerVTKOpen(((PetscObject)ts)->comm,filename,FILE_MODE_WRITE,&viewer);CHKERRQ(ierr);
3616   ierr = VecView(u,viewer);CHKERRQ(ierr);
3617   ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
3618   PetscFunctionReturn(0);
3619 }
3620 
3621 #undef __FUNCT__
3622 #define __FUNCT__ "TSMonitorSolutionVTKDestroy"
3623 /*@C
3624    TSMonitorSolutionVTKDestroy - Destroy context for monitoring
3625 
3626    Collective on TS
3627 
3628    Input Parameters:
3629 .  filenametemplate - string containing a format specifier for the integer time step (e.g. %03D)
3630 
3631    Level: intermediate
3632 
3633    Note:
3634    This function is normally passed to TSMonitorSet() along with TSMonitorSolutionVTK().
3635 
3636 .keywords: TS,  vector, monitor, view
3637 
3638 .seealso: TSMonitorSet(), TSMonitorSolutionVTK()
3639 @*/
3640 PetscErrorCode TSMonitorSolutionVTKDestroy(void *filenametemplate)
3641 {
3642   PetscErrorCode ierr;
3643 
3644   PetscFunctionBegin;
3645   ierr = PetscFree(*(char**)filenametemplate);CHKERRQ(ierr);
3646   PetscFunctionReturn(0);
3647 }
3648 
3649 #undef __FUNCT__
3650 #define __FUNCT__ "TSGetTSAdapt"
3651 /*@
3652    TSGetTSAdapt - Get the adaptive controller context for the current method
3653 
3654    Collective on TS if controller has not been created yet
3655 
3656    Input Arguments:
3657 .  ts - time stepping context
3658 
3659    Output Arguments:
3660 .  adapt - adaptive controller
3661 
3662    Level: intermediate
3663 
3664 .seealso: TSAdapt, TSAdaptSetType(), TSAdaptChoose()
3665 @*/
3666 PetscErrorCode TSGetTSAdapt(TS ts,TSAdapt *adapt)
3667 {
3668   PetscErrorCode ierr;
3669 
3670   PetscFunctionBegin;
3671   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3672   PetscValidPointer(adapt,2);
3673   if (!ts->adapt) {
3674     ierr = TSAdaptCreate(((PetscObject)ts)->comm,&ts->adapt);CHKERRQ(ierr);
3675     ierr = PetscLogObjectParent(ts,ts->adapt);CHKERRQ(ierr);
3676     ierr = PetscObjectIncrementTabLevel((PetscObject)ts->adapt,(PetscObject)ts,1);CHKERRQ(ierr);
3677   }
3678   *adapt = ts->adapt;
3679   PetscFunctionReturn(0);
3680 }
3681 
3682 #undef __FUNCT__
3683 #define __FUNCT__ "TSSetTolerances"
3684 /*@
3685    TSSetTolerances - Set tolerances for local truncation error when using adaptive controller
3686 
3687    Logically Collective
3688 
3689    Input Arguments:
3690 +  ts - time integration context
3691 .  atol - scalar absolute tolerances, PETSC_DECIDE to leave current value
3692 .  vatol - vector of absolute tolerances or PETSC_NULL, used in preference to atol if present
3693 .  rtol - scalar relative tolerances, PETSC_DECIDE to leave current value
3694 -  vrtol - vector of relative tolerances or PETSC_NULL, used in preference to atol if present
3695 
3696    Level: beginner
3697 
3698 .seealso: TS, TSAdapt, TSVecNormWRMS(), TSGetTolerances()
3699 @*/
3700 PetscErrorCode TSSetTolerances(TS ts,PetscReal atol,Vec vatol,PetscReal rtol,Vec vrtol)
3701 {
3702   PetscErrorCode ierr;
3703 
3704   PetscFunctionBegin;
3705   if (atol != PETSC_DECIDE && atol != PETSC_DEFAULT) ts->atol = atol;
3706   if (vatol) {
3707     ierr = PetscObjectReference((PetscObject)vatol);CHKERRQ(ierr);
3708     ierr = VecDestroy(&ts->vatol);CHKERRQ(ierr);
3709     ts->vatol = vatol;
3710   }
3711   if (rtol != PETSC_DECIDE && rtol != PETSC_DEFAULT) ts->rtol = rtol;
3712   if (vrtol) {
3713     ierr = PetscObjectReference((PetscObject)vrtol);CHKERRQ(ierr);
3714     ierr = VecDestroy(&ts->vrtol);CHKERRQ(ierr);
3715     ts->vrtol = vrtol;
3716   }
3717   PetscFunctionReturn(0);
3718 }
3719 
3720 #undef __FUNCT__
3721 #define __FUNCT__ "TSGetTolerances"
3722 /*@
3723    TSGetTolerances - Get tolerances for local truncation error when using adaptive controller
3724 
3725    Logically Collective
3726 
3727    Input Arguments:
3728 .  ts - time integration context
3729 
3730    Output Arguments:
3731 +  atol - scalar absolute tolerances, PETSC_NULL to ignore
3732 .  vatol - vector of absolute tolerances, PETSC_NULL to ignore
3733 .  rtol - scalar relative tolerances, PETSC_NULL to ignore
3734 -  vrtol - vector of relative tolerances, PETSC_NULL to ignore
3735 
3736    Level: beginner
3737 
3738 .seealso: TS, TSAdapt, TSVecNormWRMS(), TSSetTolerances()
3739 @*/
3740 PetscErrorCode TSGetTolerances(TS ts,PetscReal *atol,Vec *vatol,PetscReal *rtol,Vec *vrtol)
3741 {
3742   PetscFunctionBegin;
3743   if (atol)  *atol  = ts->atol;
3744   if (vatol) *vatol = ts->vatol;
3745   if (rtol)  *rtol  = ts->rtol;
3746   if (vrtol) *vrtol = ts->vrtol;
3747   PetscFunctionReturn(0);
3748 }
3749 
3750 #undef __FUNCT__
3751 #define __FUNCT__ "TSErrorNormWRMS"
3752 /*@
3753    TSErrorNormWRMS - compute a weighted norm of the difference between a vector and the current state
3754 
3755    Collective on TS
3756 
3757    Input Arguments:
3758 +  ts - time stepping context
3759 -  Y - state vector to be compared to ts->vec_sol
3760 
3761    Output Arguments:
3762 .  norm - weighted norm, a value of 1.0 is considered small
3763 
3764    Level: developer
3765 
3766 .seealso: TSSetTolerances()
3767 @*/
3768 PetscErrorCode TSErrorNormWRMS(TS ts,Vec Y,PetscReal *norm)
3769 {
3770   PetscErrorCode    ierr;
3771   PetscInt          i,n,N;
3772   const PetscScalar *u,*y;
3773   Vec               U;
3774   PetscReal         sum,gsum;
3775 
3776   PetscFunctionBegin;
3777   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3778   PetscValidHeaderSpecific(Y,VEC_CLASSID,2);
3779   PetscValidPointer(norm,3);
3780   U = ts->vec_sol;
3781   PetscCheckSameTypeAndComm(U,1,Y,2);
3782   if (U == Y) SETERRQ(((PetscObject)U)->comm,PETSC_ERR_ARG_IDN,"Y cannot be the TS solution vector");
3783 
3784   ierr = VecGetSize(U,&N);CHKERRQ(ierr);
3785   ierr = VecGetLocalSize(U,&n);CHKERRQ(ierr);
3786   ierr = VecGetArrayRead(U,&u);CHKERRQ(ierr);
3787   ierr = VecGetArrayRead(Y,&y);CHKERRQ(ierr);
3788   sum = 0.;
3789   if (ts->vatol && ts->vrtol) {
3790     const PetscScalar *atol,*rtol;
3791     ierr = VecGetArrayRead(ts->vatol,&atol);CHKERRQ(ierr);
3792     ierr = VecGetArrayRead(ts->vrtol,&rtol);CHKERRQ(ierr);
3793     for (i=0; i<n; i++) {
3794       PetscReal tol = PetscRealPart(atol[i]) + PetscRealPart(rtol[i]) * PetscMax(PetscAbsScalar(u[i]),PetscAbsScalar(y[i]));
3795       sum += PetscSqr(PetscAbsScalar(y[i] - u[i]) / tol);
3796     }
3797     ierr = VecRestoreArrayRead(ts->vatol,&atol);CHKERRQ(ierr);
3798     ierr = VecRestoreArrayRead(ts->vrtol,&rtol);CHKERRQ(ierr);
3799   } else if (ts->vatol) {       /* vector atol, scalar rtol */
3800     const PetscScalar *atol;
3801     ierr = VecGetArrayRead(ts->vatol,&atol);CHKERRQ(ierr);
3802     for (i=0; i<n; i++) {
3803       PetscReal tol = PetscRealPart(atol[i]) + ts->rtol * PetscMax(PetscAbsScalar(u[i]),PetscAbsScalar(y[i]));
3804       sum += PetscSqr(PetscAbsScalar(y[i] - u[i]) / tol);
3805     }
3806     ierr = VecRestoreArrayRead(ts->vatol,&atol);CHKERRQ(ierr);
3807   } else if (ts->vrtol) {       /* scalar atol, vector rtol */
3808     const PetscScalar *rtol;
3809     ierr = VecGetArrayRead(ts->vrtol,&rtol);CHKERRQ(ierr);
3810     for (i=0; i<n; i++) {
3811       PetscReal tol = ts->atol + PetscRealPart(rtol[i]) * PetscMax(PetscAbsScalar(u[i]),PetscAbsScalar(y[i]));
3812       sum += PetscSqr(PetscAbsScalar(y[i] - u[i]) / tol);
3813     }
3814     ierr = VecRestoreArrayRead(ts->vrtol,&rtol);CHKERRQ(ierr);
3815   } else {                      /* scalar atol, scalar rtol */
3816     for (i=0; i<n; i++) {
3817       PetscReal tol = ts->atol + ts->rtol * PetscMax(PetscAbsScalar(u[i]),PetscAbsScalar(y[i]));
3818       sum += PetscSqr(PetscAbsScalar(y[i] - u[i]) / tol);
3819     }
3820   }
3821   ierr = VecRestoreArrayRead(U,&u);CHKERRQ(ierr);
3822   ierr = VecRestoreArrayRead(Y,&y);CHKERRQ(ierr);
3823 
3824   ierr = MPI_Allreduce(&sum,&gsum,1,MPIU_REAL,MPIU_SUM,((PetscObject)ts)->comm);CHKERRQ(ierr);
3825   *norm = PetscSqrtReal(gsum / N);
3826   if (PetscIsInfOrNanScalar(*norm)) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_FP,"Infinite or not-a-number generated in norm");
3827   PetscFunctionReturn(0);
3828 }
3829 
3830 #undef __FUNCT__
3831 #define __FUNCT__ "TSSetCFLTimeLocal"
3832 /*@
3833    TSSetCFLTimeLocal - Set the local CFL constraint relative to forward Euler
3834 
3835    Logically Collective on TS
3836 
3837    Input Arguments:
3838 +  ts - time stepping context
3839 -  cfltime - maximum stable time step if using forward Euler (value can be different on each process)
3840 
3841    Note:
3842    After calling this function, the global CFL time can be obtained by calling TSGetCFLTime()
3843 
3844    Level: intermediate
3845 
3846 .seealso: TSGetCFLTime(), TSADAPTCFL
3847 @*/
3848 PetscErrorCode TSSetCFLTimeLocal(TS ts,PetscReal cfltime)
3849 {
3850   PetscFunctionBegin;
3851   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
3852   ts->cfltime_local = cfltime;
3853   ts->cfltime = -1.;
3854   PetscFunctionReturn(0);
3855 }
3856 
3857 #undef __FUNCT__
3858 #define __FUNCT__ "TSGetCFLTime"
3859 /*@
3860    TSGetCFLTime - Get the maximum stable time step according to CFL criteria applied to forward Euler
3861 
3862    Collective on TS
3863 
3864    Input Arguments:
3865 .  ts - time stepping context
3866 
3867    Output Arguments:
3868 .  cfltime - maximum stable time step for forward Euler
3869 
3870    Level: advanced
3871 
3872 .seealso: TSSetCFLTimeLocal()
3873 @*/
3874 PetscErrorCode TSGetCFLTime(TS ts,PetscReal *cfltime)
3875 {
3876   PetscErrorCode ierr;
3877 
3878   PetscFunctionBegin;
3879   if (ts->cfltime < 0) {
3880     ierr = MPI_Allreduce(&ts->cfltime_local,&ts->cfltime,1,MPIU_REAL,MPIU_MIN,((PetscObject)ts)->comm);CHKERRQ(ierr);
3881   }
3882   *cfltime = ts->cfltime;
3883   PetscFunctionReturn(0);
3884 }
3885 
3886 #undef __FUNCT__
3887 #define __FUNCT__ "TSVISetVariableBounds"
3888 /*@
3889    TSVISetVariableBounds - Sets the lower and upper bounds for the solution vector. xl <= x <= xu
3890 
3891    Input Parameters:
3892 .  ts   - the TS context.
3893 .  xl   - lower bound.
3894 .  xu   - upper bound.
3895 
3896    Notes:
3897    If this routine is not called then the lower and upper bounds are set to
3898    SNES_VI_NINF and SNES_VI_INF respectively during SNESSetUp().
3899 
3900    Level: advanced
3901 
3902 @*/
3903 PetscErrorCode TSVISetVariableBounds(TS ts, Vec xl, Vec xu)
3904 {
3905   PetscErrorCode ierr;
3906   SNES           snes;
3907 
3908   PetscFunctionBegin;
3909   ierr = TSGetSNES(ts,&snes);CHKERRQ(ierr);
3910   ierr = SNESVISetVariableBounds(snes,xl,xu);CHKERRQ(ierr);
3911   PetscFunctionReturn(0);
3912 }
3913 
3914 #if defined(PETSC_HAVE_MATLAB_ENGINE)
3915 #include <mex.h>
3916 
3917 typedef struct {char *funcname; mxArray *ctx;} TSMatlabContext;
3918 
3919 #undef __FUNCT__
3920 #define __FUNCT__ "TSComputeFunction_Matlab"
3921 /*
3922    TSComputeFunction_Matlab - Calls the function that has been set with
3923                          TSSetFunctionMatlab().
3924 
3925    Collective on TS
3926 
3927    Input Parameters:
3928 +  snes - the TS context
3929 -  u - input vector
3930 
3931    Output Parameter:
3932 .  y - function vector, as set by TSSetFunction()
3933 
3934    Notes:
3935    TSComputeFunction() is typically used within nonlinear solvers
3936    implementations, so most users would not generally call this routine
3937    themselves.
3938 
3939    Level: developer
3940 
3941 .keywords: TS, nonlinear, compute, function
3942 
3943 .seealso: TSSetFunction(), TSGetFunction()
3944 */
3945 PetscErrorCode  TSComputeFunction_Matlab(TS snes,PetscReal time,Vec u,Vec udot,Vec y, void *ctx)
3946 {
3947   PetscErrorCode   ierr;
3948   TSMatlabContext *sctx = (TSMatlabContext *)ctx;
3949   int              nlhs = 1,nrhs = 7;
3950   mxArray          *plhs[1],*prhs[7];
3951   long long int    lx = 0,lxdot = 0,ly = 0,ls = 0;
3952 
3953   PetscFunctionBegin;
3954   PetscValidHeaderSpecific(snes,TS_CLASSID,1);
3955   PetscValidHeaderSpecific(u,VEC_CLASSID,3);
3956   PetscValidHeaderSpecific(udot,VEC_CLASSID,4);
3957   PetscValidHeaderSpecific(y,VEC_CLASSID,5);
3958   PetscCheckSameComm(snes,1,u,3);
3959   PetscCheckSameComm(snes,1,y,5);
3960 
3961   ierr = PetscMemcpy(&ls,&snes,sizeof(snes));CHKERRQ(ierr);
3962   ierr = PetscMemcpy(&lx,&u,sizeof(u));CHKERRQ(ierr);
3963   ierr = PetscMemcpy(&lxdot,&udot,sizeof(udot));CHKERRQ(ierr);
3964   ierr = PetscMemcpy(&ly,&y,sizeof(u));CHKERRQ(ierr);
3965   prhs[0] =  mxCreateDoubleScalar((double)ls);
3966   prhs[1] =  mxCreateDoubleScalar(time);
3967   prhs[2] =  mxCreateDoubleScalar((double)lx);
3968   prhs[3] =  mxCreateDoubleScalar((double)lxdot);
3969   prhs[4] =  mxCreateDoubleScalar((double)ly);
3970   prhs[5] =  mxCreateString(sctx->funcname);
3971   prhs[6] =  sctx->ctx;
3972   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscTSComputeFunctionInternal");CHKERRQ(ierr);
3973   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
3974   mxDestroyArray(prhs[0]);
3975   mxDestroyArray(prhs[1]);
3976   mxDestroyArray(prhs[2]);
3977   mxDestroyArray(prhs[3]);
3978   mxDestroyArray(prhs[4]);
3979   mxDestroyArray(prhs[5]);
3980   mxDestroyArray(plhs[0]);
3981   PetscFunctionReturn(0);
3982 }
3983 
3984 
3985 #undef __FUNCT__
3986 #define __FUNCT__ "TSSetFunctionMatlab"
3987 /*
3988    TSSetFunctionMatlab - Sets the function evaluation routine and function
3989    vector for use by the TS routines in solving ODEs
3990    equations from MATLAB. Here the function is a string containing the name of a MATLAB function
3991 
3992    Logically Collective on TS
3993 
3994    Input Parameters:
3995 +  ts - the TS context
3996 -  func - function evaluation routine
3997 
3998    Calling sequence of func:
3999 $    func (TS ts,PetscReal time,Vec u,Vec udot,Vec f,void *ctx);
4000 
4001    Level: beginner
4002 
4003 .keywords: TS, nonlinear, set, function
4004 
4005 .seealso: TSGetFunction(), TSComputeFunction(), TSSetJacobian(), TSSetFunction()
4006 */
4007 PetscErrorCode  TSSetFunctionMatlab(TS ts,const char *func,mxArray *ctx)
4008 {
4009   PetscErrorCode  ierr;
4010   TSMatlabContext *sctx;
4011 
4012   PetscFunctionBegin;
4013   /* currently sctx is memory bleed */
4014   ierr = PetscMalloc(sizeof(TSMatlabContext),&sctx);CHKERRQ(ierr);
4015   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4016   /*
4017      This should work, but it doesn't
4018   sctx->ctx = ctx;
4019   mexMakeArrayPersistent(sctx->ctx);
4020   */
4021   sctx->ctx = mxDuplicateArray(ctx);
4022   ierr = TSSetIFunction(ts,PETSC_NULL,TSComputeFunction_Matlab,sctx);CHKERRQ(ierr);
4023   PetscFunctionReturn(0);
4024 }
4025 
4026 #undef __FUNCT__
4027 #define __FUNCT__ "TSComputeJacobian_Matlab"
4028 /*
4029    TSComputeJacobian_Matlab - Calls the function that has been set with
4030                          TSSetJacobianMatlab().
4031 
4032    Collective on TS
4033 
4034    Input Parameters:
4035 +  ts - the TS context
4036 .  u - input vector
4037 .  A, B - the matrices
4038 -  ctx - user context
4039 
4040    Output Parameter:
4041 .  flag - structure of the matrix
4042 
4043    Level: developer
4044 
4045 .keywords: TS, nonlinear, compute, function
4046 
4047 .seealso: TSSetFunction(), TSGetFunction()
4048 @*/
4049 PetscErrorCode  TSComputeJacobian_Matlab(TS ts,PetscReal time,Vec u,Vec udot,PetscReal shift,Mat *A,Mat *B,MatStructure *flag, void *ctx)
4050 {
4051   PetscErrorCode  ierr;
4052   TSMatlabContext *sctx = (TSMatlabContext *)ctx;
4053   int             nlhs = 2,nrhs = 9;
4054   mxArray         *plhs[2],*prhs[9];
4055   long long int   lx = 0,lxdot = 0,lA = 0,ls = 0, lB = 0;
4056 
4057   PetscFunctionBegin;
4058   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
4059   PetscValidHeaderSpecific(u,VEC_CLASSID,3);
4060 
4061   /* call Matlab function in ctx with arguments u and y */
4062 
4063   ierr = PetscMemcpy(&ls,&ts,sizeof(ts));CHKERRQ(ierr);
4064   ierr = PetscMemcpy(&lx,&u,sizeof(u));CHKERRQ(ierr);
4065   ierr = PetscMemcpy(&lxdot,&udot,sizeof(u));CHKERRQ(ierr);
4066   ierr = PetscMemcpy(&lA,A,sizeof(u));CHKERRQ(ierr);
4067   ierr = PetscMemcpy(&lB,B,sizeof(u));CHKERRQ(ierr);
4068   prhs[0] =  mxCreateDoubleScalar((double)ls);
4069   prhs[1] =  mxCreateDoubleScalar((double)time);
4070   prhs[2] =  mxCreateDoubleScalar((double)lx);
4071   prhs[3] =  mxCreateDoubleScalar((double)lxdot);
4072   prhs[4] =  mxCreateDoubleScalar((double)shift);
4073   prhs[5] =  mxCreateDoubleScalar((double)lA);
4074   prhs[6] =  mxCreateDoubleScalar((double)lB);
4075   prhs[7] =  mxCreateString(sctx->funcname);
4076   prhs[8] =  sctx->ctx;
4077   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscTSComputeJacobianInternal");CHKERRQ(ierr);
4078   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4079   *flag   =  (MatStructure) mxGetScalar(plhs[1]);CHKERRQ(ierr);
4080   mxDestroyArray(prhs[0]);
4081   mxDestroyArray(prhs[1]);
4082   mxDestroyArray(prhs[2]);
4083   mxDestroyArray(prhs[3]);
4084   mxDestroyArray(prhs[4]);
4085   mxDestroyArray(prhs[5]);
4086   mxDestroyArray(prhs[6]);
4087   mxDestroyArray(prhs[7]);
4088   mxDestroyArray(plhs[0]);
4089   mxDestroyArray(plhs[1]);
4090   PetscFunctionReturn(0);
4091 }
4092 
4093 
4094 #undef __FUNCT__
4095 #define __FUNCT__ "TSSetJacobianMatlab"
4096 /*
4097    TSSetJacobianMatlab - Sets the Jacobian function evaluation routine and two empty Jacobian matrices
4098    vector for use by the TS routines in solving ODEs from MATLAB. Here the function is a string containing the name of a MATLAB function
4099 
4100    Logically Collective on TS
4101 
4102    Input Parameters:
4103 +  ts - the TS context
4104 .  A,B - Jacobian matrices
4105 .  func - function evaluation routine
4106 -  ctx - user context
4107 
4108    Calling sequence of func:
4109 $    flag = func (TS ts,PetscReal time,Vec u,Vec udot,Mat A,Mat B,void *ctx);
4110 
4111 
4112    Level: developer
4113 
4114 .keywords: TS, nonlinear, set, function
4115 
4116 .seealso: TSGetFunction(), TSComputeFunction(), TSSetJacobian(), TSSetFunction()
4117 */
4118 PetscErrorCode  TSSetJacobianMatlab(TS ts,Mat A,Mat B,const char *func,mxArray *ctx)
4119 {
4120   PetscErrorCode    ierr;
4121   TSMatlabContext *sctx;
4122 
4123   PetscFunctionBegin;
4124   /* currently sctx is memory bleed */
4125   ierr = PetscMalloc(sizeof(TSMatlabContext),&sctx);CHKERRQ(ierr);
4126   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4127   /*
4128      This should work, but it doesn't
4129   sctx->ctx = ctx;
4130   mexMakeArrayPersistent(sctx->ctx);
4131   */
4132   sctx->ctx = mxDuplicateArray(ctx);
4133   ierr = TSSetIJacobian(ts,A,B,TSComputeJacobian_Matlab,sctx);CHKERRQ(ierr);
4134   PetscFunctionReturn(0);
4135 }
4136 
4137 #undef __FUNCT__
4138 #define __FUNCT__ "TSMonitor_Matlab"
4139 /*
4140    TSMonitor_Matlab - Calls the function that has been set with TSMonitorSetMatlab().
4141 
4142    Collective on TS
4143 
4144 .seealso: TSSetFunction(), TSGetFunction()
4145 @*/
4146 PetscErrorCode  TSMonitor_Matlab(TS ts,PetscInt it, PetscReal time,Vec u, void *ctx)
4147 {
4148   PetscErrorCode  ierr;
4149   TSMatlabContext *sctx = (TSMatlabContext *)ctx;
4150   int             nlhs = 1,nrhs = 6;
4151   mxArray         *plhs[1],*prhs[6];
4152   long long int   lx = 0,ls = 0;
4153 
4154   PetscFunctionBegin;
4155   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
4156   PetscValidHeaderSpecific(u,VEC_CLASSID,4);
4157 
4158   ierr = PetscMemcpy(&ls,&ts,sizeof(ts));CHKERRQ(ierr);
4159   ierr = PetscMemcpy(&lx,&u,sizeof(u));CHKERRQ(ierr);
4160   prhs[0] =  mxCreateDoubleScalar((double)ls);
4161   prhs[1] =  mxCreateDoubleScalar((double)it);
4162   prhs[2] =  mxCreateDoubleScalar((double)time);
4163   prhs[3] =  mxCreateDoubleScalar((double)lx);
4164   prhs[4] =  mxCreateString(sctx->funcname);
4165   prhs[5] =  sctx->ctx;
4166   ierr    =  mexCallMATLAB(nlhs,plhs,nrhs,prhs,"PetscTSMonitorInternal");CHKERRQ(ierr);
4167   ierr    =  mxGetScalar(plhs[0]);CHKERRQ(ierr);
4168   mxDestroyArray(prhs[0]);
4169   mxDestroyArray(prhs[1]);
4170   mxDestroyArray(prhs[2]);
4171   mxDestroyArray(prhs[3]);
4172   mxDestroyArray(prhs[4]);
4173   mxDestroyArray(plhs[0]);
4174   PetscFunctionReturn(0);
4175 }
4176 
4177 
4178 #undef __FUNCT__
4179 #define __FUNCT__ "TSMonitorSetMatlab"
4180 /*
4181    TSMonitorSetMatlab - Sets the monitor function from Matlab
4182 
4183    Level: developer
4184 
4185 .keywords: TS, nonlinear, set, function
4186 
4187 .seealso: TSGetFunction(), TSComputeFunction(), TSSetJacobian(), TSSetFunction()
4188 */
4189 PetscErrorCode  TSMonitorSetMatlab(TS ts,const char *func,mxArray *ctx)
4190 {
4191   PetscErrorCode    ierr;
4192   TSMatlabContext *sctx;
4193 
4194   PetscFunctionBegin;
4195   /* currently sctx is memory bleed */
4196   ierr = PetscMalloc(sizeof(TSMatlabContext),&sctx);CHKERRQ(ierr);
4197   ierr = PetscStrallocpy(func,&sctx->funcname);CHKERRQ(ierr);
4198   /*
4199      This should work, but it doesn't
4200   sctx->ctx = ctx;
4201   mexMakeArrayPersistent(sctx->ctx);
4202   */
4203   sctx->ctx = mxDuplicateArray(ctx);
4204   ierr = TSMonitorSet(ts,TSMonitor_Matlab,sctx,PETSC_NULL);CHKERRQ(ierr);
4205   PetscFunctionReturn(0);
4206 }
4207 #endif
4208 
4209 
4210 
4211 #undef __FUNCT__
4212 #define __FUNCT__ "TSMonitorLGSolution"
4213 /*@C
4214    TSMonitorLGSolution - Monitors progress of the TS solvers by plotting each component of the solution vector
4215        in a time based line graph
4216 
4217    Collective on TS
4218 
4219    Input Parameters:
4220 +  ts - the TS context
4221 .  step - current time-step
4222 .  ptime - current time
4223 -  lg - a line graph object
4224 
4225    Level: intermediate
4226 
4227     Notes: each process in a parallel run displays its component solutions in a separate window
4228 
4229 .keywords: TS,  vector, monitor, view
4230 
4231 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView()
4232 @*/
4233 PetscErrorCode  TSMonitorLGSolution(TS ts,PetscInt step,PetscReal ptime,Vec u,void *dummy)
4234 {
4235   PetscErrorCode    ierr;
4236   TSMonitorLGCtx    ctx = (TSMonitorLGCtx)dummy;
4237   const PetscScalar *yy;
4238   PetscInt          dim;
4239 
4240   PetscFunctionBegin;
4241   if (!step) {
4242     PetscDrawAxis  axis;
4243     ierr = PetscDrawLGGetAxis(ctx->lg,&axis);CHKERRQ(ierr);
4244     ierr = PetscDrawAxisSetLabels(axis,"Solution as function of time","Time","Solution");CHKERRQ(ierr);
4245     ierr = VecGetLocalSize(u,&dim);CHKERRQ(ierr);
4246     ierr = PetscDrawLGSetDimension(ctx->lg,dim);CHKERRQ(ierr);
4247     ierr = PetscDrawLGReset(ctx->lg);CHKERRQ(ierr);
4248   }
4249   ierr = VecGetArrayRead(u,&yy);CHKERRQ(ierr);
4250 #if defined(PETSC_USE_COMPLEX)
4251   {
4252     PetscReal *yreal;
4253     PetscInt i,n;
4254     ierr = VecGetLocalSize(u,&n);CHKERRQ(ierr);
4255     ierr = PetscMalloc(n*sizeof(PetscReal),&yreal);CHKERRQ(ierr);
4256     for (i=0; i<n; i++) yreal[i] = PetscRealPart(yy[i]);
4257     ierr = PetscDrawLGAddCommonPoint(ctx->lg,ptime,yreal);CHKERRQ(ierr);
4258     ierr = PetscFree(yreal);CHKERRQ(ierr);
4259   }
4260 #else
4261   ierr = PetscDrawLGAddCommonPoint(ctx->lg,ptime,yy);CHKERRQ(ierr);
4262 #endif
4263   ierr = VecRestoreArrayRead(u,&yy);CHKERRQ(ierr);
4264   if (((ctx->howoften > 0) && (!(step % ctx->howoften)) && (step > -1)) || ((ctx->howoften == -1) && (step == -1))){
4265     ierr = PetscDrawLGDraw(ctx->lg);CHKERRQ(ierr);
4266   }
4267   PetscFunctionReturn(0);
4268 }
4269 
4270 #undef __FUNCT__
4271 #define __FUNCT__ "TSMonitorLGError"
4272 /*@C
4273    TSMonitorLGError - Monitors progress of the TS solvers by plotting each component of the solution vector
4274        in a time based line graph
4275 
4276    Collective on TS
4277 
4278    Input Parameters:
4279 +  ts - the TS context
4280 .  step - current time-step
4281 .  ptime - current time
4282 -  lg - a line graph object
4283 
4284    Level: intermediate
4285 
4286    Notes:
4287    Only for sequential solves.
4288 
4289    The user must provide the solution using TSSetSolutionFunction() to use this monitor.
4290 
4291    Options Database Keys:
4292 .  -ts_monitor_lg_error - create a graphical monitor of error history
4293 
4294 .keywords: TS,  vector, monitor, view
4295 
4296 .seealso: TSMonitorSet(), TSMonitorDefault(), VecView(), TSSetSolutionFunction()
4297 @*/
4298 PetscErrorCode  TSMonitorLGError(TS ts,PetscInt step,PetscReal ptime,Vec u,void *dummy)
4299 {
4300   PetscErrorCode    ierr;
4301   TSMonitorLGCtx    ctx = (TSMonitorLGCtx)dummy;
4302   const PetscScalar *yy;
4303   Vec               y;
4304   PetscInt          dim;
4305 
4306   PetscFunctionBegin;
4307   if (!step) {
4308     PetscDrawAxis  axis;
4309     ierr = PetscDrawLGGetAxis(ctx->lg,&axis);CHKERRQ(ierr);
4310     ierr = PetscDrawAxisSetLabels(axis,"Error in solution as function of time","Time","Solution");CHKERRQ(ierr);
4311     ierr = VecGetLocalSize(u,&dim);CHKERRQ(ierr);
4312     ierr = PetscDrawLGSetDimension(ctx->lg,dim);CHKERRQ(ierr);
4313     ierr = PetscDrawLGReset(ctx->lg);CHKERRQ(ierr);
4314   }
4315   ierr = VecDuplicate(u,&y);CHKERRQ(ierr);
4316   ierr = TSComputeSolutionFunction(ts,ptime,y);CHKERRQ(ierr);
4317   ierr = VecAXPY(y,-1.0,u);CHKERRQ(ierr);
4318   ierr = VecGetArrayRead(y,&yy);CHKERRQ(ierr);
4319 #if defined(PETSC_USE_COMPLEX)
4320   {
4321     PetscReal *yreal;
4322     PetscInt  i,n;
4323     ierr = VecGetLocalSize(y,&n);CHKERRQ(ierr);
4324     ierr = PetscMalloc(n*sizeof(PetscReal),&yreal);CHKERRQ(ierr);
4325     for (i=0; i<n; i++) yreal[i] = PetscRealPart(yy[i]);
4326     ierr = PetscDrawLGAddCommonPoint(ctx->lg,ptime,yreal);CHKERRQ(ierr);
4327     ierr = PetscFree(yreal);CHKERRQ(ierr);
4328   }
4329 #else
4330   ierr = PetscDrawLGAddCommonPoint(ctx->lg,ptime,yy);CHKERRQ(ierr);
4331 #endif
4332   ierr = VecRestoreArrayRead(y,&yy);CHKERRQ(ierr);
4333   ierr = VecDestroy(&y);CHKERRQ(ierr);
4334   if (((ctx->howoften > 0) && (!(step % ctx->howoften)) && (step > -1)) || ((ctx->howoften == -1) && (step == -1))){
4335     ierr = PetscDrawLGDraw(ctx->lg);CHKERRQ(ierr);
4336   }
4337   PetscFunctionReturn(0);
4338 }
4339 
4340 #undef __FUNCT__
4341 #define __FUNCT__ "TSMonitorLGSNESIterations"
4342 PetscErrorCode TSMonitorLGSNESIterations(TS ts,PetscInt n,PetscReal ptime,Vec v,void *monctx)
4343 {
4344   TSMonitorLGCtx ctx = (TSMonitorLGCtx) monctx;
4345   PetscReal      x = ptime,y;
4346   PetscErrorCode ierr;
4347   PetscInt       its;
4348 
4349   PetscFunctionBegin;
4350   if (!n) {
4351     PetscDrawAxis  axis;
4352     ierr = PetscDrawLGGetAxis(ctx->lg,&axis);CHKERRQ(ierr);
4353     ierr = PetscDrawAxisSetLabels(axis,"Nonlinear iterations as function of time","Time","SNES Iterations");CHKERRQ(ierr);
4354     ierr = PetscDrawLGReset(ctx->lg);CHKERRQ(ierr);
4355     ctx->snes_its  = 0;
4356   }
4357   ierr = TSGetSNESIterations(ts,&its);CHKERRQ(ierr);
4358   y    = its - ctx->snes_its;
4359   ierr = PetscDrawLGAddPoint(ctx->lg,&x,&y);CHKERRQ(ierr);
4360   if (((ctx->howoften > 0) && (!(n % ctx->howoften)) && (n > -1)) || ((ctx->howoften == -1) && (n == -1))){
4361     ierr = PetscDrawLGDraw(ctx->lg);CHKERRQ(ierr);
4362   }
4363   ctx->snes_its = its;
4364   PetscFunctionReturn(0);
4365 }
4366 
4367 #undef __FUNCT__
4368 #define __FUNCT__ "TSMonitorLGKSPIterations"
4369 PetscErrorCode TSMonitorLGKSPIterations(TS ts,PetscInt n,PetscReal ptime,Vec v,void *monctx)
4370 {
4371   TSMonitorLGCtx ctx = (TSMonitorLGCtx) monctx;
4372   PetscReal      x = ptime,y;
4373   PetscErrorCode ierr;
4374   PetscInt       its;
4375 
4376   PetscFunctionBegin;
4377   if (!n) {
4378     PetscDrawAxis  axis;
4379     ierr = PetscDrawLGGetAxis(ctx->lg,&axis);CHKERRQ(ierr);
4380     ierr = PetscDrawAxisSetLabels(axis,"Linear iterations as function of time","Time","KSP Iterations");CHKERRQ(ierr);
4381     ierr = PetscDrawLGReset(ctx->lg);CHKERRQ(ierr);
4382     ctx->ksp_its = 0;
4383   }
4384   ierr = TSGetKSPIterations(ts,&its);CHKERRQ(ierr);
4385   y    = its - ctx->ksp_its;
4386   ierr = PetscDrawLGAddPoint(ctx->lg,&x,&y);CHKERRQ(ierr);
4387   if (((ctx->howoften > 0) && (!(n % ctx->howoften)) && (n > -1)) || ((ctx->howoften == -1) && (n == -1))){
4388     ierr = PetscDrawLGDraw(ctx->lg);CHKERRQ(ierr);
4389   }
4390   ctx->ksp_its = its;
4391   PetscFunctionReturn(0);
4392 }
4393 
4394 #undef __FUNCT__
4395 #define __FUNCT__ "TSComputeLinearStability"
4396 /*@
4397    TSComputeLinearStability - computes the linear stability function at a point
4398 
4399    Collective on TS and Vec
4400 
4401    Input Parameters:
4402 +  ts - the TS context
4403 -  xr,xi - real and imaginary part of input arguments
4404 
4405    Output Parameters:
4406 .  yr,yi - real and imaginary part of function value
4407 
4408    Level: developer
4409 
4410 .keywords: TS, compute
4411 
4412 .seealso: TSSetRHSFunction(), TSComputeIFunction()
4413 @*/
4414 PetscErrorCode TSComputeLinearStability(TS ts,PetscReal xr,PetscReal xi,PetscReal *yr,PetscReal *yi)
4415 {
4416   PetscErrorCode ierr;
4417 
4418   PetscFunctionBegin;
4419   PetscValidHeaderSpecific(ts,TS_CLASSID,1);
4420   if (!ts->ops->linearstability) SETERRQ(((PetscObject)ts)->comm,PETSC_ERR_SUP,"Linearized stability function not provided for this method");
4421   ierr = (*ts->ops->linearstability)(ts,xr,xi,yr,yi);CHKERRQ(ierr);
4422   PetscFunctionReturn(0);
4423 }
4424