xref: /petsc/src/snes/impls/vi/ss/viss.c (revision 5e71baeff2f3138f93cd4f5927dfd596eb8325cc)
1 
2 #include <../src/snes/impls/vi/ss/vissimpl.h> /*I "petscsnes.h" I*/
3 
4 /*
5   SNESVIComputeMeritFunction - Evaluates the merit function for the mixed complementarity problem.
6 
7   Input Parameter:
8 . phi - the semismooth function
9 
10   Output Parameter:
11 . merit - the merit function
12 . phinorm - ||phi||
13 
14   Notes:
15   The merit function for the mixed complementarity problem is defined as
16      merit = 0.5*phi^T*phi
17 */
18 static PetscErrorCode SNESVIComputeMeritFunction(Vec phi, PetscReal *merit,PetscReal *phinorm)
19 {
20   PetscErrorCode ierr;
21 
22   PetscFunctionBegin;
23   ierr = VecNormBegin(phi,NORM_2,phinorm);CHKERRQ(ierr);
24   ierr = VecNormEnd(phi,NORM_2,phinorm);CHKERRQ(ierr);
25 
26   *merit = 0.5*(*phinorm)*(*phinorm);
27   PetscFunctionReturn(0);
28 }
29 
30 PETSC_STATIC_INLINE PetscScalar Phi(PetscScalar a,PetscScalar b)
31 {
32   return a + b - PetscSqrtScalar(a*a + b*b);
33 }
34 
35 PETSC_STATIC_INLINE PetscScalar DPhi(PetscScalar a,PetscScalar b)
36 {
37   if ((PetscAbsScalar(a) >= 1.e-6) || (PetscAbsScalar(b) >= 1.e-6)) return 1.0 - a/ PetscSqrtScalar(a*a + b*b);
38   else return .5;
39 }
40 
41 /*
42    SNESVIComputeFunction - Reformulates a system of nonlinear equations in mixed complementarity form to a system of nonlinear equations in semismooth form.
43 
44    Input Parameters:
45 .  snes - the SNES context
46 .  X - current iterate
47 .  functx - user defined function context
48 
49    Output Parameters:
50 .  phi - Semismooth function
51 
52 */
53 static PetscErrorCode SNESVIComputeFunction(SNES snes,Vec X,Vec phi,void *functx)
54 {
55   PetscErrorCode    ierr;
56   SNES_VINEWTONSSLS *vi = (SNES_VINEWTONSSLS*)snes->data;
57   Vec               Xl  = snes->xl,Xu = snes->xu,F = snes->vec_func;
58   PetscScalar       *phi_arr,*f_arr,*l,*u;
59   const PetscScalar *x_arr;
60   PetscInt          i,nlocal;
61 
62   PetscFunctionBegin;
63   ierr = (*vi->computeuserfunction)(snes,X,F,functx);CHKERRQ(ierr);
64   ierr = VecGetLocalSize(X,&nlocal);CHKERRQ(ierr);
65   ierr = VecGetArrayRead(X,&x_arr);CHKERRQ(ierr);
66   ierr = VecGetArray(F,&f_arr);CHKERRQ(ierr);
67   ierr = VecGetArray(Xl,&l);CHKERRQ(ierr);
68   ierr = VecGetArray(Xu,&u);CHKERRQ(ierr);
69   ierr = VecGetArray(phi,&phi_arr);CHKERRQ(ierr);
70 
71   for (i=0; i < nlocal; i++) {
72     if ((PetscRealPart(l[i]) <= PETSC_NINFINITY) && (PetscRealPart(u[i]) >= PETSC_INFINITY)) { /* no constraints on variable */
73       phi_arr[i] = f_arr[i];
74     } else if (PetscRealPart(l[i]) <= PETSC_NINFINITY) {                      /* upper bound on variable only */
75       phi_arr[i] = -Phi(u[i] - x_arr[i],-f_arr[i]);
76     } else if (PetscRealPart(u[i]) >= PETSC_INFINITY) {                       /* lower bound on variable only */
77       phi_arr[i] = Phi(x_arr[i] - l[i],f_arr[i]);
78     } else if (l[i] == u[i]) {
79       phi_arr[i] = l[i] - x_arr[i];
80     } else {                                                /* both bounds on variable */
81       phi_arr[i] = Phi(x_arr[i] - l[i],-Phi(u[i] - x_arr[i],-f_arr[i]));
82     }
83   }
84 
85   ierr = VecRestoreArrayRead(X,&x_arr);CHKERRQ(ierr);
86   ierr = VecRestoreArray(F,&f_arr);CHKERRQ(ierr);
87   ierr = VecRestoreArray(Xl,&l);CHKERRQ(ierr);
88   ierr = VecRestoreArray(Xu,&u);CHKERRQ(ierr);
89   ierr = VecRestoreArray(phi,&phi_arr);CHKERRQ(ierr);
90   PetscFunctionReturn(0);
91 }
92 
93 /*
94    SNESVIComputeBsubdifferentialVectors - Computes the diagonal shift (Da) and row scaling (Db) vectors needed for the
95                                           the semismooth jacobian.
96 */
97 PetscErrorCode SNESVIComputeBsubdifferentialVectors(SNES snes,Vec X,Vec F,Mat jac,Vec Da,Vec Db)
98 {
99   PetscErrorCode ierr;
100   PetscScalar    *l,*u,*x,*f,*da,*db,da1,da2,db1,db2;
101   PetscInt       i,nlocal;
102 
103   PetscFunctionBegin;
104   ierr = VecGetArray(X,&x);CHKERRQ(ierr);
105   ierr = VecGetArray(F,&f);CHKERRQ(ierr);
106   ierr = VecGetArray(snes->xl,&l);CHKERRQ(ierr);
107   ierr = VecGetArray(snes->xu,&u);CHKERRQ(ierr);
108   ierr = VecGetArray(Da,&da);CHKERRQ(ierr);
109   ierr = VecGetArray(Db,&db);CHKERRQ(ierr);
110   ierr = VecGetLocalSize(X,&nlocal);CHKERRQ(ierr);
111 
112   for (i=0; i< nlocal; i++) {
113     if ((PetscRealPart(l[i]) <= PETSC_NINFINITY) && (PetscRealPart(u[i]) >= PETSC_INFINITY)) { /* no constraints on variable */
114       da[i] = 0;
115       db[i] = 1;
116     } else if (PetscRealPart(l[i]) <= PETSC_NINFINITY) {                     /* upper bound on variable only */
117       da[i] = DPhi(u[i] - x[i], -f[i]);
118       db[i] = DPhi(-f[i],u[i] - x[i]);
119     } else if (PetscRealPart(u[i]) >= PETSC_INFINITY) {                      /* lower bound on variable only */
120       da[i] = DPhi(x[i] - l[i], f[i]);
121       db[i] = DPhi(f[i],x[i] - l[i]);
122     } else if (l[i] == u[i]) {                              /* fixed variable */
123       da[i] = 1;
124       db[i] = 0;
125     } else {                                                /* upper and lower bounds on variable */
126       da1   = DPhi(x[i] - l[i], -Phi(u[i] - x[i], -f[i]));
127       db1   = DPhi(-Phi(u[i] - x[i], -f[i]),x[i] - l[i]);
128       da2   = DPhi(u[i] - x[i], -f[i]);
129       db2   = DPhi(-f[i],u[i] - x[i]);
130       da[i] = da1 + db1*da2;
131       db[i] = db1*db2;
132     }
133   }
134 
135   ierr = VecRestoreArray(X,&x);CHKERRQ(ierr);
136   ierr = VecRestoreArray(F,&f);CHKERRQ(ierr);
137   ierr = VecRestoreArray(snes->xl,&l);CHKERRQ(ierr);
138   ierr = VecRestoreArray(snes->xu,&u);CHKERRQ(ierr);
139   ierr = VecRestoreArray(Da,&da);CHKERRQ(ierr);
140   ierr = VecRestoreArray(Db,&db);CHKERRQ(ierr);
141   PetscFunctionReturn(0);
142 }
143 
144 /*
145    SNESVIComputeJacobian - Computes the jacobian of the semismooth function.The Jacobian for the semismooth function is an element of the B-subdifferential of the Fischer-Burmeister function for complementarity problems.
146 
147    Input Parameters:
148 .  Da       - Diagonal shift vector for the semismooth jacobian.
149 .  Db       - Row scaling vector for the semismooth jacobian.
150 
151    Output Parameters:
152 .  jac      - semismooth jacobian
153 .  jac_pre  - optional preconditioning matrix
154 
155    Notes:
156    The semismooth jacobian matrix is given by
157    jac = Da + Db*jacfun
158    where Db is the row scaling matrix stored as a vector,
159          Da is the diagonal perturbation matrix stored as a vector
160    and   jacfun is the jacobian of the original nonlinear function.
161 */
162 PetscErrorCode SNESVIComputeJacobian(Mat jac, Mat jac_pre,Vec Da, Vec Db)
163 {
164   PetscErrorCode ierr;
165 
166   /* Do row scaling  and add diagonal perturbation */
167   ierr = MatDiagonalScale(jac,Db,NULL);CHKERRQ(ierr);
168   ierr = MatDiagonalSet(jac,Da,ADD_VALUES);CHKERRQ(ierr);
169   if (jac != jac_pre) { /* If jac and jac_pre are different */
170     ierr = MatDiagonalScale(jac_pre,Db,NULL);CHKERRQ(ierr);
171     ierr = MatDiagonalSet(jac_pre,Da,ADD_VALUES);CHKERRQ(ierr);
172   }
173   PetscFunctionReturn(0);
174 }
175 
176 /*
177    SNESVIComputeMeritFunctionGradient - Computes the gradient of the merit function psi.
178 
179    Input Parameters:
180    phi - semismooth function.
181    H   - semismooth jacobian
182 
183    Output Parameters:
184    dpsi - merit function gradient
185 
186    Notes:
187   The merit function gradient is computed as follows
188         dpsi = H^T*phi
189 */
190 PetscErrorCode SNESVIComputeMeritFunctionGradient(Mat H, Vec phi, Vec dpsi)
191 {
192   PetscErrorCode ierr;
193 
194   PetscFunctionBegin;
195   ierr = MatMultTranspose(H,phi,dpsi);CHKERRQ(ierr);
196   PetscFunctionReturn(0);
197 }
198 
199 
200 
201 /*
202    SNESSolve_VINEWTONSSLS - Solves the complementarity problem with a semismooth Newton
203    method using a line search.
204 
205    Input Parameters:
206 .  snes - the SNES context
207 
208    Application Interface Routine: SNESSolve()
209 
210    Notes:
211    This implements essentially a semismooth Newton method with a
212    line search. The default line search does not do any line search
213    but rather takes a full Newton step.
214 
215    Developer Note: the code in this file should be slightly modified so that this routine need not exist and the SNESSolve_NEWTONLS() routine is called directly with the appropriate wrapped function and Jacobian evaluations
216 
217 */
218 PetscErrorCode SNESSolve_VINEWTONSSLS(SNES snes)
219 {
220   SNES_VINEWTONSSLS    *vi = (SNES_VINEWTONSSLS*)snes->data;
221   PetscErrorCode       ierr;
222   PetscInt             maxits,i,lits;
223   SNESLineSearchReason lssucceed;
224   PetscReal            gnorm,xnorm=0,ynorm;
225   Vec                  Y,X,F;
226   KSPConvergedReason   kspreason;
227   DM                   dm;
228   DMSNES               sdm;
229 
230   PetscFunctionBegin;
231   ierr = SNESGetDM(snes,&dm);CHKERRQ(ierr);
232   ierr = DMGetDMSNES(dm,&sdm);CHKERRQ(ierr);
233 
234   vi->computeuserfunction   = sdm->ops->computefunction;
235   sdm->ops->computefunction = SNESVIComputeFunction;
236 
237   snes->numFailures            = 0;
238   snes->numLinearSolveFailures = 0;
239   snes->reason                 = SNES_CONVERGED_ITERATING;
240 
241   maxits = snes->max_its;               /* maximum number of iterations */
242   X      = snes->vec_sol;               /* solution vector */
243   F      = snes->vec_func;              /* residual vector */
244   Y      = snes->work[0];               /* work vectors */
245 
246   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
247   snes->iter = 0;
248   snes->norm = 0.0;
249   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
250 
251   ierr = SNESVIProjectOntoBounds(snes,X);CHKERRQ(ierr);
252   ierr = SNESComputeFunction(snes,X,vi->phi);CHKERRQ(ierr);
253   if (snes->domainerror) {
254     snes->reason              = SNES_DIVERGED_FUNCTION_DOMAIN;
255     sdm->ops->computefunction = vi->computeuserfunction;
256     PetscFunctionReturn(0);
257   }
258   /* Compute Merit function */
259   ierr = SNESVIComputeMeritFunction(vi->phi,&vi->merit,&vi->phinorm);CHKERRQ(ierr);
260 
261   ierr = VecNormBegin(X,NORM_2,&xnorm);CHKERRQ(ierr);        /* xnorm <- ||x||  */
262   ierr = VecNormEnd(X,NORM_2,&xnorm);CHKERRQ(ierr);
263   SNESCheckFunctionNorm(snes,vi->merit);
264 
265   ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
266   snes->norm = vi->phinorm;
267   ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
268   ierr       = SNESLogConvergenceHistory(snes,vi->phinorm,0);CHKERRQ(ierr);
269   ierr       = SNESMonitor(snes,0,vi->phinorm);CHKERRQ(ierr);
270 
271   /* test convergence */
272   ierr = (*snes->ops->converged)(snes,0,0.0,0.0,vi->phinorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
273   if (snes->reason) {
274     sdm->ops->computefunction = vi->computeuserfunction;
275     PetscFunctionReturn(0);
276   }
277 
278   for (i=0; i<maxits; i++) {
279 
280     /* Call general purpose update function */
281     if (snes->ops->update) {
282       ierr = (*snes->ops->update)(snes, snes->iter);CHKERRQ(ierr);
283     }
284 
285     /* Solve J Y = Phi, where J is the semismooth jacobian */
286 
287     /* Get the jacobian -- note that the function must be the original function for snes_fd and snes_fd_color to work for this*/
288     sdm->ops->computefunction = vi->computeuserfunction;
289     ierr                      = SNESComputeJacobian(snes,X,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
290     sdm->ops->computefunction = SNESVIComputeFunction;
291 
292     /* Get the diagonal shift and row scaling vectors */
293     ierr = SNESVIComputeBsubdifferentialVectors(snes,X,F,snes->jacobian,vi->Da,vi->Db);CHKERRQ(ierr);
294     /* Compute the semismooth jacobian */
295     ierr = SNESVIComputeJacobian(snes->jacobian,snes->jacobian_pre,vi->Da,vi->Db);CHKERRQ(ierr);
296     /* Compute the merit function gradient */
297     ierr = SNESVIComputeMeritFunctionGradient(snes->jacobian,vi->phi,vi->dpsi);CHKERRQ(ierr);
298     ierr = KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);CHKERRQ(ierr);
299     ierr = KSPSolve(snes->ksp,vi->phi,Y);CHKERRQ(ierr);
300     ierr = KSPGetConvergedReason(snes->ksp,&kspreason);CHKERRQ(ierr);
301 
302     if (kspreason < 0) {
303       if (++snes->numLinearSolveFailures >= snes->maxLinearSolveFailures) {
304         ierr         = PetscInfo2(snes,"iter=%D, number linear solve failures %D greater than current SNES allowed, stopping solve\n",snes->iter,snes->numLinearSolveFailures);CHKERRQ(ierr);
305         snes->reason = SNES_DIVERGED_LINEAR_SOLVE;
306         break;
307       }
308     }
309     ierr              = KSPGetIterationNumber(snes->ksp,&lits);CHKERRQ(ierr);
310     snes->linear_its += lits;
311     ierr              = PetscInfo2(snes,"iter=%D, linear solve iterations=%D\n",snes->iter,lits);CHKERRQ(ierr);
312     /*
313     if (snes->ops->precheck) {
314       PetscBool changed_y = PETSC_FALSE;
315       ierr = (*snes->ops->precheck)(snes,X,Y,snes->precheck,&changed_y);CHKERRQ(ierr);
316     }
317 
318     if (PetscLogPrintInfo) {
319       ierr = SNESVICheckResidual_Private(snes,snes->jacobian,F,Y,G,W);CHKERRQ(ierr);
320     }
321     */
322     /* Compute a (scaled) negative update in the line search routine:
323          Y <- X - lambda*Y
324        and evaluate G = function(Y) (depends on the line search).
325     */
326     ierr  = VecCopy(Y,snes->vec_sol_update);CHKERRQ(ierr);
327     ynorm = 1; gnorm = vi->phinorm;
328     ierr = SNESLineSearchApply(snes->linesearch, X, vi->phi, &gnorm, Y);CHKERRQ(ierr);
329     ierr = SNESLineSearchGetReason(snes->linesearch, &lssucceed);CHKERRQ(ierr);
330     ierr = SNESLineSearchGetNorms(snes->linesearch, &xnorm, &gnorm, &ynorm);CHKERRQ(ierr);
331     ierr = PetscInfo4(snes,"fnorm=%18.16e, gnorm=%18.16e, ynorm=%18.16e, lssucceed=%d\n",(double)vi->phinorm,(double)gnorm,(double)ynorm,(int)lssucceed);CHKERRQ(ierr);
332     if (snes->reason == SNES_DIVERGED_FUNCTION_COUNT) break;
333     if (snes->domainerror) {
334       snes->reason              = SNES_DIVERGED_FUNCTION_DOMAIN;
335       sdm->ops->computefunction = vi->computeuserfunction;
336       PetscFunctionReturn(0);
337     }
338     if (lssucceed) {
339       if (++snes->numFailures >= snes->maxFailures) {
340         PetscBool ismin;
341         snes->reason = SNES_DIVERGED_LINE_SEARCH;
342         ierr         = SNESVICheckLocalMin_Private(snes,snes->jacobian,vi->phi,X,gnorm,&ismin);CHKERRQ(ierr);
343         if (ismin) snes->reason = SNES_DIVERGED_LOCAL_MIN;
344         break;
345       }
346     }
347     /* Update function and solution vectors */
348     vi->phinorm = gnorm;
349     vi->merit   = 0.5*vi->phinorm*vi->phinorm;
350     /* Monitor convergence */
351     ierr       = PetscObjectSAWsTakeAccess((PetscObject)snes);CHKERRQ(ierr);
352     snes->iter = i+1;
353     snes->norm = vi->phinorm;
354     ierr       = PetscObjectSAWsGrantAccess((PetscObject)snes);CHKERRQ(ierr);
355     ierr       = SNESLogConvergenceHistory(snes,snes->norm,lits);CHKERRQ(ierr);
356     ierr       = SNESMonitor(snes,snes->iter,snes->norm);CHKERRQ(ierr);
357     /* Test for convergence, xnorm = || X || */
358     if (snes->ops->converged != SNESConvergedSkip) { ierr = VecNorm(X,NORM_2,&xnorm);CHKERRQ(ierr); }
359     ierr = (*snes->ops->converged)(snes,snes->iter,xnorm,ynorm,vi->phinorm,&snes->reason,snes->cnvP);CHKERRQ(ierr);
360     if (snes->reason) break;
361   }
362   if (i == maxits) {
363     ierr = PetscInfo1(snes,"Maximum number of iterations has been reached: %D\n",maxits);CHKERRQ(ierr);
364     if (!snes->reason) snes->reason = SNES_DIVERGED_MAX_IT;
365   }
366   sdm->ops->computefunction = vi->computeuserfunction;
367   PetscFunctionReturn(0);
368 }
369 
370 /* -------------------------------------------------------------------------- */
371 /*
372    SNESSetUp_VINEWTONSSLS - Sets up the internal data structures for the later use
373    of the SNES nonlinear solver.
374 
375    Input Parameter:
376 .  snes - the SNES context
377 
378    Application Interface Routine: SNESSetUp()
379 
380    Notes:
381    For basic use of the SNES solvers, the user need not explicitly call
382    SNESSetUp(), since these actions will automatically occur during
383    the call to SNESSolve().
384  */
385 PetscErrorCode SNESSetUp_VINEWTONSSLS(SNES snes)
386 {
387   PetscErrorCode    ierr;
388   SNES_VINEWTONSSLS *vi = (SNES_VINEWTONSSLS*) snes->data;
389 
390   PetscFunctionBegin;
391   ierr = SNESSetUp_VI(snes);CHKERRQ(ierr);
392   ierr = VecDuplicate(snes->vec_sol, &vi->dpsi);CHKERRQ(ierr);
393   ierr = VecDuplicate(snes->vec_sol, &vi->phi);CHKERRQ(ierr);
394   ierr = VecDuplicate(snes->vec_sol, &vi->Da);CHKERRQ(ierr);
395   ierr = VecDuplicate(snes->vec_sol, &vi->Db);CHKERRQ(ierr);
396   ierr = VecDuplicate(snes->vec_sol, &vi->z);CHKERRQ(ierr);
397   ierr = VecDuplicate(snes->vec_sol, &vi->t);CHKERRQ(ierr);
398   PetscFunctionReturn(0);
399 }
400 /* -------------------------------------------------------------------------- */
401 PetscErrorCode SNESReset_VINEWTONSSLS(SNES snes)
402 {
403   SNES_VINEWTONSSLS *vi = (SNES_VINEWTONSSLS*) snes->data;
404   PetscErrorCode    ierr;
405 
406   PetscFunctionBegin;
407   ierr = SNESReset_VI(snes);CHKERRQ(ierr);
408   ierr = VecDestroy(&vi->dpsi);CHKERRQ(ierr);
409   ierr = VecDestroy(&vi->phi);CHKERRQ(ierr);
410   ierr = VecDestroy(&vi->Da);CHKERRQ(ierr);
411   ierr = VecDestroy(&vi->Db);CHKERRQ(ierr);
412   ierr = VecDestroy(&vi->z);CHKERRQ(ierr);
413   ierr = VecDestroy(&vi->t);CHKERRQ(ierr);
414   PetscFunctionReturn(0);
415 }
416 
417 /* -------------------------------------------------------------------------- */
418 /*
419    SNESSetFromOptions_VINEWTONSSLS - Sets various parameters for the SNESVI method.
420 
421    Input Parameter:
422 .  snes - the SNES context
423 
424    Application Interface Routine: SNESSetFromOptions()
425 */
426 static PetscErrorCode SNESSetFromOptions_VINEWTONSSLS(PetscOptionItems *PetscOptionsObject,SNES snes)
427 {
428   PetscErrorCode ierr;
429   SNESLineSearch linesearch;
430 
431   PetscFunctionBegin;
432   ierr = SNESSetFromOptions_VI(PetscOptionsObject,snes);CHKERRQ(ierr);
433   ierr = PetscOptionsHead(PetscOptionsObject,"SNES semismooth method options");CHKERRQ(ierr);
434   ierr = PetscOptionsTail();CHKERRQ(ierr);
435   /* set up the default line search */
436   if (!snes->linesearch) {
437     ierr = SNESGetLineSearch(snes, &linesearch);CHKERRQ(ierr);
438     ierr = SNESLineSearchSetType(linesearch, SNESLINESEARCHBT);CHKERRQ(ierr);
439     ierr = SNESLineSearchBTSetAlpha(linesearch, 0.0);CHKERRQ(ierr);
440   }
441   PetscFunctionReturn(0);
442 }
443 
444 
445 /* -------------------------------------------------------------------------- */
446 /*MC
447       SNESVINEWTONSSLS - Semi-smooth solver for variational inequalities based on Newton's method
448 
449    Options Database:
450 +   -snes_type <vinewtonssls,vinewtonrsls> a semi-smooth solver, a reduced space active set method
451 -   -snes_vi_monitor - prints the number of active constraints at each iteration.
452 
453    Level: beginner
454 
455    References:
456 +  1. -  T. S. Munson, F. Facchinei, M. C. Ferris, A. Fischer, and C. Kanzow. The semismooth
457      algorithm for large scale complementarity problems. INFORMS Journal on Computing, 13 (2001).
458 -  2. -  T. S. Munson, and S. Benson. Flexible Complementarity Solvers for Large Scale
459      Applications, Optimization Methods and Software, 21 (2006).
460 
461 .seealso:  SNESVISetVariableBounds(), SNESVISetComputeVariableBounds(), SNESCreate(), SNES, SNESSetType(), SNESVINEWTONRSLS, SNESNEWTONTR, SNESLineSearchSetType(),SNESLineSearchSetPostCheck(), SNESLineSearchSetPreCheck()
462 
463 M*/
464 PETSC_EXTERN PetscErrorCode SNESCreate_VINEWTONSSLS(SNES snes)
465 {
466   PetscErrorCode    ierr;
467   SNES_VINEWTONSSLS *vi;
468 
469   PetscFunctionBegin;
470   snes->ops->reset          = SNESReset_VINEWTONSSLS;
471   snes->ops->setup          = SNESSetUp_VINEWTONSSLS;
472   snes->ops->solve          = SNESSolve_VINEWTONSSLS;
473   snes->ops->destroy        = SNESDestroy_VI;
474   snes->ops->setfromoptions = SNESSetFromOptions_VINEWTONSSLS;
475   snes->ops->view           = NULL;
476 
477   snes->usesksp = PETSC_TRUE;
478   snes->usesnpc = PETSC_FALSE;
479 
480   snes->alwayscomputesfinalresidual = PETSC_FALSE;
481 
482   ierr       = PetscNewLog(snes,&vi);CHKERRQ(ierr);
483   snes->data = (void*)vi;
484 
485   ierr = PetscObjectComposeFunction((PetscObject)snes,"SNESVISetVariableBounds_C",SNESVISetVariableBounds_VI);CHKERRQ(ierr);
486   ierr = PetscObjectComposeFunction((PetscObject)snes,"SNESVISetComputeVariableBounds_C",SNESVISetComputeVariableBounds_VI);CHKERRQ(ierr);
487   PetscFunctionReturn(0);
488 }
489 
490