xref: /petsc/include/petscsnes.h (revision 6dd63270497ad23dcf16ae500a87ff2b2a0b7474)
1 /*
2     User interface for the nonlinear solvers package.
3 */
4 #pragma once
5 
6 #include <petscksp.h>
7 #include <petscdmtypes.h>
8 #include <petscfvtypes.h>
9 #include <petscdmdatypes.h>
10 #include <petscsnestypes.h>
11 
12 /* SUBMANSEC = SNES */
13 
14 /*J
15    SNESType - String with the name of a PETSc `SNES` method. These are all the nonlinear solvers that PETSc provides.
16 
17    Level: beginner
18 
19    Note:
20    Use `SNESSetType()` or the options database key `-snes_type` to set the specific nonlinear solver algorithm to use with a given `SNES` object
21 
22 .seealso: [](doc_nonlinsolve), [](ch_snes), `SNESSetType()`, `SNES`, `SNESCreate()`, `SNESDestroy()`, `SNESSetFromOptions()`
23 J*/
24 typedef const char *SNESType;
25 #define SNESNEWTONLS         "newtonls"
26 #define SNESNEWTONTR         "newtontr"
27 #define SNESNEWTONTRDC       "newtontrdc"
28 #define SNESPYTHON           "python"
29 #define SNESNRICHARDSON      "nrichardson"
30 #define SNESKSPONLY          "ksponly"
31 #define SNESKSPTRANSPOSEONLY "ksptransposeonly"
32 #define SNESVINEWTONRSLS     "vinewtonrsls"
33 #define SNESVINEWTONSSLS     "vinewtonssls"
34 #define SNESNGMRES           "ngmres"
35 #define SNESQN               "qn"
36 #define SNESSHELL            "shell"
37 #define SNESNGS              "ngs"
38 #define SNESNCG              "ncg"
39 #define SNESFAS              "fas"
40 #define SNESMS               "ms"
41 #define SNESNASM             "nasm"
42 #define SNESANDERSON         "anderson"
43 #define SNESASPIN            "aspin"
44 #define SNESCOMPOSITE        "composite"
45 #define SNESPATCH            "patch"
46 #define SNESNEWTONAL         "newtonal"
47 
48 /* Logging support */
49 PETSC_EXTERN PetscClassId SNES_CLASSID;
50 PETSC_EXTERN PetscClassId DMSNES_CLASSID;
51 
52 PETSC_EXTERN PetscErrorCode SNESInitializePackage(void);
53 PETSC_EXTERN PetscErrorCode SNESFinalizePackage(void);
54 
55 PETSC_EXTERN PetscErrorCode SNESCreate(MPI_Comm, SNES *);
56 PETSC_EXTERN PetscErrorCode SNESParametersInitialize(SNES);
57 PETSC_EXTERN PetscErrorCode SNESReset(SNES);
58 PETSC_EXTERN PetscErrorCode SNESDestroy(SNES *);
59 PETSC_EXTERN PetscErrorCode SNESSetType(SNES, SNESType);
60 PETSC_EXTERN PetscErrorCode SNESMonitor(SNES, PetscInt, PetscReal);
61 PETSC_EXTERN PetscErrorCode SNESMonitorSet(SNES, PetscErrorCode (*)(SNES, PetscInt, PetscReal, void *), void *, PetscCtxDestroyFn *);
62 PETSC_EXTERN PetscErrorCode SNESMonitorSetFromOptions(SNES, const char[], const char[], const char[], PetscErrorCode (*)(SNES, PetscInt, PetscReal, PetscViewerAndFormat *), PetscErrorCode (*)(SNES, PetscViewerAndFormat *));
63 PETSC_EXTERN PetscErrorCode SNESMonitorCancel(SNES);
64 PETSC_EXTERN PetscErrorCode SNESMonitorSAWs(SNES, PetscInt, PetscReal, void *);
65 PETSC_EXTERN PetscErrorCode SNESMonitorSAWsCreate(SNES, void **);
66 PETSC_EXTERN PetscErrorCode SNESMonitorSAWsDestroy(void **);
67 PETSC_EXTERN PetscErrorCode SNESSetConvergenceHistory(SNES, PetscReal[], PetscInt[], PetscInt, PetscBool);
68 PETSC_EXTERN PetscErrorCode SNESGetConvergenceHistory(SNES, PetscReal *[], PetscInt *[], PetscInt *);
69 PETSC_EXTERN PetscErrorCode SNESSetUp(SNES);
70 PETSC_EXTERN PetscErrorCode SNESSolve(SNES, Vec, Vec);
71 PETSC_EXTERN PetscErrorCode SNESSetErrorIfNotConverged(SNES, PetscBool);
72 PETSC_EXTERN PetscErrorCode SNESGetErrorIfNotConverged(SNES, PetscBool *);
73 PETSC_EXTERN PetscErrorCode SNESConverged(SNES, PetscInt, PetscReal, PetscReal, PetscReal);
74 
75 PETSC_EXTERN PetscErrorCode SNESSetWorkVecs(SNES, PetscInt);
76 
77 PETSC_EXTERN PetscErrorCode SNESAddOptionsChecker(PetscErrorCode (*)(SNES));
78 
79 PETSC_EXTERN PetscErrorCode SNESRegister(const char[], PetscErrorCode (*)(SNES));
80 
81 PETSC_EXTERN PetscErrorCode SNESGetKSP(SNES, KSP *);
82 PETSC_EXTERN PetscErrorCode SNESSetKSP(SNES, KSP);
83 PETSC_EXTERN PetscErrorCode SNESSetSolution(SNES, Vec);
84 PETSC_EXTERN PetscErrorCode SNESGetSolution(SNES, Vec *);
85 PETSC_EXTERN PetscErrorCode SNESGetSolutionUpdate(SNES, Vec *);
86 PETSC_EXTERN PetscErrorCode SNESGetRhs(SNES, Vec *);
87 PETSC_EXTERN PetscErrorCode SNESView(SNES, PetscViewer);
88 PETSC_EXTERN PetscErrorCode SNESLoad(SNES, PetscViewer);
89 PETSC_EXTERN PetscErrorCode SNESConvergedReasonViewSet(SNES, PetscErrorCode (*)(SNES, void *), void *, PetscCtxDestroyFn *);
90 PETSC_EXTERN PetscErrorCode SNESViewFromOptions(SNES, PetscObject, const char[]);
91 PETSC_EXTERN PetscErrorCode SNESConvergedReasonView(SNES, PetscViewer);
92 PETSC_EXTERN PetscErrorCode SNESConvergedReasonViewFromOptions(SNES);
93 PETSC_EXTERN PetscErrorCode SNESConvergedReasonViewCancel(SNES);
94 
95 PETSC_DEPRECATED_FUNCTION(3, 14, 0, "SNESConvergedReasonView()", ) static inline PetscErrorCode SNESReasonView(SNES snes, PetscViewer v)
96 {
97   return SNESConvergedReasonView(snes, v);
98 }
99 PETSC_DEPRECATED_FUNCTION(3, 14, 0, "SNESConvergedReasonViewFromOptions()", ) static inline PetscErrorCode SNESReasonViewFromOptions(SNES snes)
100 {
101   return SNESConvergedReasonViewFromOptions(snes);
102 }
103 
104 #define SNES_FILE_CLASSID 1211224
105 
106 PETSC_EXTERN PetscErrorCode SNESSetOptionsPrefix(SNES, const char[]);
107 PETSC_EXTERN PetscErrorCode SNESAppendOptionsPrefix(SNES, const char[]);
108 PETSC_EXTERN PetscErrorCode SNESGetOptionsPrefix(SNES, const char *[]);
109 PETSC_EXTERN PetscErrorCode SNESSetFromOptions(SNES);
110 PETSC_EXTERN PetscErrorCode SNESResetFromOptions(SNES);
111 
112 PETSC_EXTERN PetscErrorCode SNESSetUseMatrixFree(SNES, PetscBool, PetscBool);
113 PETSC_EXTERN PetscErrorCode SNESGetUseMatrixFree(SNES, PetscBool *, PetscBool *);
114 PETSC_EXTERN PetscErrorCode MatCreateSNESMF(SNES, Mat *);
115 PETSC_EXTERN PetscErrorCode MatSNESMFGetSNES(Mat, SNES *);
116 PETSC_EXTERN PetscErrorCode MatSNESMFSetReuseBase(Mat, PetscBool);
117 PETSC_EXTERN PetscErrorCode MatSNESMFGetReuseBase(Mat, PetscBool *);
118 PETSC_EXTERN PetscErrorCode MatMFFDComputeJacobian(SNES, Vec, Mat, Mat, void *);
119 PETSC_EXTERN PetscErrorCode MatCreateSNESMFMore(SNES, Vec, Mat *);
120 PETSC_EXTERN PetscErrorCode MatSNESMFMoreSetParameters(Mat, PetscReal, PetscReal, PetscReal);
121 
122 PETSC_EXTERN PetscErrorCode SNESGetType(SNES, SNESType *);
123 PETSC_EXTERN PetscErrorCode SNESMonitorDefaultSetUp(SNES, PetscViewerAndFormat *);
124 PETSC_EXTERN PetscErrorCode SNESMonitorDefault(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
125 PETSC_EXTERN PetscErrorCode SNESMonitorScaling(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
126 PETSC_EXTERN PetscErrorCode SNESMonitorRange(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
127 PETSC_EXTERN PetscErrorCode SNESMonitorRatio(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
128 PETSC_EXTERN PetscErrorCode SNESMonitorRatioSetUp(SNES, PetscViewerAndFormat *);
129 PETSC_EXTERN PetscErrorCode SNESMonitorSolution(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
130 PETSC_EXTERN PetscErrorCode SNESMonitorResidual(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
131 PETSC_EXTERN PetscErrorCode SNESMonitorSolutionUpdate(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
132 PETSC_EXTERN PetscErrorCode SNESMonitorDefaultShort(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
133 PETSC_EXTERN PetscErrorCode SNESMonitorDefaultField(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
134 PETSC_EXTERN PetscErrorCode SNESMonitorJacUpdateSpectrum(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
135 PETSC_EXTERN PetscErrorCode SNESMonitorFields(SNES, PetscInt, PetscReal, PetscViewerAndFormat *);
136 PETSC_EXTERN PetscErrorCode KSPMonitorSNESResidual(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
137 PETSC_EXTERN PetscErrorCode KSPMonitorSNESResidualDrawLG(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
138 PETSC_EXTERN PetscErrorCode KSPMonitorSNESResidualDrawLGCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);
139 
140 PETSC_EXTERN PetscErrorCode SNESSetTolerances(SNES, PetscReal, PetscReal, PetscReal, PetscInt, PetscInt);
141 PETSC_EXTERN PetscErrorCode SNESSetDivergenceTolerance(SNES, PetscReal);
142 PETSC_EXTERN PetscErrorCode SNESGetTolerances(SNES, PetscReal *, PetscReal *, PetscReal *, PetscInt *, PetscInt *);
143 PETSC_EXTERN PetscErrorCode SNESGetDivergenceTolerance(SNES, PetscReal *);
144 PETSC_EXTERN PetscErrorCode SNESGetForceIteration(SNES, PetscBool *);
145 PETSC_EXTERN PetscErrorCode SNESSetForceIteration(SNES, PetscBool);
146 PETSC_EXTERN PetscErrorCode SNESGetIterationNumber(SNES, PetscInt *);
147 PETSC_EXTERN PetscErrorCode SNESSetIterationNumber(SNES, PetscInt);
148 
149 /*E
150    SNESNewtonTRFallbackType - type of fallback in case the solution of the trust-region subproblem is outside of the radius
151 
152    Values:
153 +  `SNES_TR_FALLBACK_NEWTON` - use scaled Newton step
154 .  `SNES_TR_FALLBACK_CAUCHY` - use Cauchy direction
155 -  `SNES_TR_FALLBACK_DOGLEG` - use dogleg method
156 
157    Level: intermediate
158 
159 .seealso: [](ch_snes), `SNES`, `SNESNEWTONTR`, `SNESNEWTONTRDC`
160 E*/
161 typedef enum {
162   SNES_TR_FALLBACK_NEWTON,
163   SNES_TR_FALLBACK_CAUCHY,
164   SNES_TR_FALLBACK_DOGLEG,
165 } SNESNewtonTRFallbackType;
166 
167 PETSC_EXTERN const char *const SNESNewtonTRFallbackTypes[];
168 
169 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetPreCheck(SNES, PetscErrorCode (*)(SNES, Vec, Vec, PetscBool *, void *), void *ctx);
170 PETSC_EXTERN PetscErrorCode SNESNewtonTRGetPreCheck(SNES, PetscErrorCode (**)(SNES, Vec, Vec, PetscBool *, void *), void **ctx);
171 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetPostCheck(SNES, PetscErrorCode (*)(SNES, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void *ctx);
172 PETSC_EXTERN PetscErrorCode SNESNewtonTRGetPostCheck(SNES, PetscErrorCode (**)(SNES, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void **ctx);
173 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetFallbackType(SNES, SNESNewtonTRFallbackType);
174 PETSC_EXTERN PetscErrorCode SNESNewtonTRPreCheck(SNES, Vec, Vec, PetscBool *);
175 PETSC_EXTERN PetscErrorCode SNESNewtonTRPostCheck(SNES, Vec, Vec, Vec, PetscBool *, PetscBool *);
176 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetNormType(SNES, NormType);
177 
178 /*E
179     SNESNewtonTRQNType - type of quasi-Newton model to use
180 
181    Values:
182 +  `SNES_TR_QN_NONE` - do not use a quasi-Newton model
183 .  `SNES_TR_QN_SAME` - use the same quasi-Newton model for matrix and preconditioner
184 -  `SNES_TR_QN_DIFFERENT` - use different quasi-Newton models for matrix and preconditioner
185 
186    Level: intermediate
187 
188 .seealso: [](ch_snes), `SNES`, `SNESNEWTONTR`
189 E*/
190 typedef enum {
191   SNES_TR_QN_NONE,
192   SNES_TR_QN_SAME,
193   SNES_TR_QN_DIFFERENT,
194 } SNESNewtonTRQNType;
195 
196 PETSC_EXTERN const char *const SNESNewtonTRQNTypes[];
197 
198 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetQNType(SNES, SNESNewtonTRQNType);
199 
200 PETSC_EXTERN PETSC_DEPRECATED_FUNCTION(3, 22, 0, "SNESNewtonTRSetTolerances()", ) PetscErrorCode SNESSetTrustRegionTolerance(SNES, PetscReal);
201 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetTolerances(SNES, PetscReal, PetscReal, PetscReal);
202 PETSC_EXTERN PetscErrorCode SNESNewtonTRGetTolerances(SNES, PetscReal *, PetscReal *, PetscReal *);
203 PETSC_EXTERN PetscErrorCode SNESNewtonTRSetUpdateParameters(SNES, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal);
204 PETSC_EXTERN PetscErrorCode SNESNewtonTRGetUpdateParameters(SNES, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscReal *);
205 
206 PETSC_EXTERN PetscErrorCode SNESNewtonTRDCGetRhoFlag(SNES, PetscBool *);
207 PETSC_EXTERN PetscErrorCode SNESNewtonTRDCSetPreCheck(SNES, PetscErrorCode (*)(SNES, Vec, Vec, PetscBool *, void *), void *ctx);
208 PETSC_EXTERN PetscErrorCode SNESNewtonTRDCGetPreCheck(SNES, PetscErrorCode (**)(SNES, Vec, Vec, PetscBool *, void *), void **ctx);
209 PETSC_EXTERN PetscErrorCode SNESNewtonTRDCSetPostCheck(SNES, PetscErrorCode (*)(SNES, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void *ctx);
210 PETSC_EXTERN PetscErrorCode SNESNewtonTRDCGetPostCheck(SNES, PetscErrorCode (**)(SNES, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void **ctx);
211 
212 PETSC_EXTERN PetscErrorCode SNESGetNonlinearStepFailures(SNES, PetscInt *);
213 PETSC_EXTERN PetscErrorCode SNESSetMaxNonlinearStepFailures(SNES, PetscInt);
214 PETSC_EXTERN PetscErrorCode SNESGetMaxNonlinearStepFailures(SNES, PetscInt *);
215 PETSC_EXTERN PetscErrorCode SNESGetNumberFunctionEvals(SNES, PetscInt *);
216 
217 PETSC_EXTERN PetscErrorCode SNESSetLagPreconditioner(SNES, PetscInt);
218 PETSC_EXTERN PetscErrorCode SNESGetLagPreconditioner(SNES, PetscInt *);
219 PETSC_EXTERN PetscErrorCode SNESSetLagJacobian(SNES, PetscInt);
220 PETSC_EXTERN PetscErrorCode SNESGetLagJacobian(SNES, PetscInt *);
221 PETSC_EXTERN PetscErrorCode SNESSetLagPreconditionerPersists(SNES, PetscBool);
222 PETSC_EXTERN PetscErrorCode SNESSetLagJacobianPersists(SNES, PetscBool);
223 PETSC_EXTERN PetscErrorCode SNESSetGridSequence(SNES, PetscInt);
224 PETSC_EXTERN PetscErrorCode SNESGetGridSequence(SNES, PetscInt *);
225 
226 PETSC_EXTERN PetscErrorCode SNESGetLinearSolveIterations(SNES, PetscInt *);
227 PETSC_EXTERN PetscErrorCode SNESGetLinearSolveFailures(SNES, PetscInt *);
228 PETSC_EXTERN PetscErrorCode SNESSetMaxLinearSolveFailures(SNES, PetscInt);
229 PETSC_EXTERN PetscErrorCode SNESGetMaxLinearSolveFailures(SNES, PetscInt *);
230 PETSC_EXTERN PetscErrorCode SNESSetCountersReset(SNES, PetscBool);
231 PETSC_EXTERN PetscErrorCode SNESResetCounters(SNES);
232 
233 PETSC_EXTERN PetscErrorCode SNESKSPSetUseEW(SNES, PetscBool);
234 PETSC_EXTERN PetscErrorCode SNESKSPGetUseEW(SNES, PetscBool *);
235 PETSC_EXTERN PetscErrorCode SNESKSPSetParametersEW(SNES, PetscInt, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal);
236 PETSC_EXTERN PetscErrorCode SNESKSPGetParametersEW(SNES, PetscInt *, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscReal *);
237 
238 PETSC_EXTERN PetscErrorCode SNESMonitorLGRange(SNES, PetscInt, PetscReal, void *);
239 
240 PETSC_EXTERN PetscErrorCode SNESSetApplicationContext(SNES, void *);
241 PETSC_EXTERN PetscErrorCode SNESGetApplicationContext(SNES, void *);
242 PETSC_EXTERN PetscErrorCode SNESSetComputeApplicationContext(SNES, PetscErrorCode (*)(SNES, void **), PetscCtxDestroyFn *);
243 
244 PETSC_EXTERN PetscErrorCode SNESPythonSetType(SNES, const char[]);
245 PETSC_EXTERN PetscErrorCode SNESPythonGetType(SNES, const char *[]);
246 
247 PETSC_EXTERN PetscErrorCode SNESSetFunctionDomainError(SNES);
248 PETSC_EXTERN PetscErrorCode SNESGetFunctionDomainError(SNES, PetscBool *);
249 PETSC_EXTERN PetscErrorCode SNESGetJacobianDomainError(SNES, PetscBool *);
250 PETSC_EXTERN PetscErrorCode SNESSetJacobianDomainError(SNES);
251 PETSC_EXTERN PetscErrorCode SNESSetCheckJacobianDomainError(SNES, PetscBool);
252 PETSC_EXTERN PetscErrorCode SNESGetCheckJacobianDomainError(SNES, PetscBool *);
253 
254 #define SNES_CONVERGED_TR_DELTA_DEPRECATED SNES_CONVERGED_TR_DELTA PETSC_DEPRECATED_ENUM(3, 12, 0, "SNES_DIVERGED_TR_DELTA", )
255 /*E
256     SNESConvergedReason - reason a `SNESSolve()` was determined to have converged or diverged
257 
258    Values:
259 +  `SNES_CONVERGED_FNORM_ABS`      - 2-norm(F) <= abstol
260 .  `SNES_CONVERGED_FNORM_RELATIVE` - 2-norm(F) <= rtol*2-norm(F(x_0)) where x_0 is the initial guess
261 .  `SNES_CONVERGED_SNORM_RELATIVE` - The 2-norm of the last step <= stol * 2-norm(x) where x is the current
262 .  `SNES_CONVERGED_USER`           - The user has indicated convergence for an arbitrary reason
263 .  `SNES_DIVERGED_FUNCTION_COUNT`  - The user provided function has been called more times than the maximum set in `SNESSetTolerances()`
264 .  `SNES_DIVERGED_DTOL`            - The norm of the function has increased by a factor of divtol set with `SNESSetDivergenceTolerance()`
265 .  `SNES_DIVERGED_FNORM_NAN`       - the 2-norm of the current function evaluation is not-a-number (NaN), this
266                                      is usually caused by a division of 0 by 0.
267 .  `SNES_DIVERGED_MAX_IT`          - `SNESSolve()` has reached the maximum number of iterations requested
268 .  `SNES_DIVERGED_LINE_SEARCH`     - The line search has failed. This only occurs for `SNES` solvers that use a line search
269 .  `SNES_DIVERGED_LOCAL_MIN`       - the algorithm seems to have stagnated at a local minimum that is not zero.
270 .  `SNES_DIVERGED_USER`            - The user has indicated divergence for an arbitrary reason
271 -  `SNES_CONVERGED_ITERATING       - this only occurs if `SNESGetConvergedReason()` is called during the `SNESSolve()`
272 
273    Level: beginner
274 
275     Notes:
276    The two most common reasons for divergence are an incorrectly coded or computed Jacobian or failure or lack of convergence in the linear system
277    (in this case we recommend
278    testing with `-pc_type lu` to eliminate the linear solver as the cause of the problem).
279 
280    `SNES_DIVERGED_LOCAL_MIN` can only occur when using a `SNES` solver that uses a line search (`SNESLineSearch`).
281    The line search wants to minimize Q(alpha) = 1/2 || F(x + alpha s) ||^2_2  this occurs
282    at Q'(alpha) = s^T F'(x+alpha s)^T F(x+alpha s) = 0. If s is the Newton direction - F'(x)^(-1)F(x) then
283    you get Q'(alpha) = -F(x)^T F'(x)^(-1)^T F'(x+alpha s)F(x+alpha s); when alpha = 0
284    Q'(0) = - ||F(x)||^2_2 which is always NEGATIVE if F'(x) is invertible. This means the Newton
285    direction is a descent direction and the line search should succeed if alpha is small enough.
286 
287    If F'(x) is NOT invertible AND F'(x)^T F(x) = 0 then Q'(0) = 0 and the Newton direction
288    is NOT a descent direction so the line search will fail. All one can do at this point
289    is change the initial guess and try again.
290 
291    An alternative explanation: Newton's method can be regarded as replacing the function with
292    its linear approximation and minimizing the 2-norm of that. That is F(x+s) approx F(x) + F'(x)s
293    so we minimize || F(x) + F'(x) s ||^2_2; do this using Least Squares. If F'(x) is invertible then
294    s = - F'(x)^(-1)F(x) otherwise F'(x)^T F'(x) s = -F'(x)^T F(x). If F'(x)^T F(x) is NOT zero then there
295    exists a nontrivial (that is F'(x)s != 0) solution to the equation and this direction is
296    s = - [F'(x)^T F'(x)]^(-1) F'(x)^T F(x) so Q'(0) = - F(x)^T F'(x) [F'(x)^T F'(x)]^(-T) F'(x)^T F(x)
297    = - (F'(x)^T F(x)) [F'(x)^T F'(x)]^(-T) (F'(x)^T F(x)). Since we are assuming (F'(x)^T F(x)) != 0
298    and F'(x)^T F'(x) has no negative eigenvalues Q'(0) < 0 so s is a descent direction and the line
299    search should succeed for small enough alpha.
300 
301    Note that this RARELY happens in practice. Far more likely the linear system is not being solved
302    (well enough?) or the Jacobian is wrong.
303 
304    `SNES_DIVERGED_MAX_IT` means that the solver reached the maximum number of iterations without satisfying any
305    convergence criteria. `SNES_CONVERGED_ITS` means that `SNESConvergedSkip()` was chosen as the convergence test;
306    thus the usual convergence criteria have not been checked and may or may not be satisfied.
307 
308 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPConvergedReason`, `SNESSetConvergenceTest()`, `SNESSetTolerances()`
309 E*/
310 typedef enum {                       /* converged */
311   SNES_CONVERGED_FNORM_ABS      = 2, /* ||F|| < atol */
312   SNES_CONVERGED_FNORM_RELATIVE = 3, /* ||F|| < rtol*||F_initial|| */
313   SNES_CONVERGED_SNORM_RELATIVE = 4, /* Newton computed step size small; || delta x || < stol || x || */
314   SNES_CONVERGED_ITS            = 5, /* maximum iterations reached */
315   SNES_BREAKOUT_INNER_ITER      = 6, /* Flag to break out of inner loop after checking custom convergence, used in multi-phase flow when state changes */
316   SNES_CONVERGED_USER           = 7, /* The user has indicated convergence for an arbitrary reason */
317   /* diverged */
318   SNES_DIVERGED_FUNCTION_DOMAIN      = -1, /* the new x location passed the function is not in the domain of F */
319   SNES_DIVERGED_FUNCTION_COUNT       = -2,
320   SNES_DIVERGED_LINEAR_SOLVE         = -3, /* the linear solve failed */
321   SNES_DIVERGED_FNORM_NAN            = -4,
322   SNES_DIVERGED_MAX_IT               = -5,
323   SNES_DIVERGED_LINE_SEARCH          = -6,  /* the line search failed */
324   SNES_DIVERGED_INNER                = -7,  /* inner solve failed */
325   SNES_DIVERGED_LOCAL_MIN            = -8,  /* || J^T b || is small, implies converged to local minimum of F() */
326   SNES_DIVERGED_DTOL                 = -9,  /* || F || > divtol*||F_initial|| */
327   SNES_DIVERGED_JACOBIAN_DOMAIN      = -10, /* Jacobian calculation does not make sense */
328   SNES_DIVERGED_TR_DELTA             = -11,
329   SNES_CONVERGED_TR_DELTA_DEPRECATED = -11,
330   SNES_DIVERGED_USER                 = -12, /* The user has indicated divergence for an arbitrary reason */
331 
332   SNES_CONVERGED_ITERATING = 0
333 } SNESConvergedReason;
334 PETSC_EXTERN const char *const *SNESConvergedReasons;
335 
336 /*MC
337    SNES_CONVERGED_FNORM_ABS - 2-norm(F) <= abstol
338 
339    Level: beginner
340 
341 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
342 M*/
343 
344 /*MC
345    SNES_CONVERGED_FNORM_RELATIVE - 2-norm(F) <= rtol*2-norm(F(x_0)) where x_0 is the initial guess
346 
347    Level: beginner
348 
349 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
350 M*/
351 
352 /*MC
353   SNES_CONVERGED_SNORM_RELATIVE - The 2-norm of the last step <= stol * 2-norm(x) where x is the current
354   solution and stol is the 4th argument to `SNESSetTolerances()`
355 
356   Options Database Key:
357   -snes_stol <stol> - the step tolerance
358 
359    Level: beginner
360 
361 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
362 M*/
363 
364 /*MC
365    SNES_DIVERGED_FUNCTION_COUNT - The user provided function has been called more times then the final
366    argument to `SNESSetTolerances()`
367 
368    Level: beginner
369 
370 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
371 M*/
372 
373 /*MC
374    SNES_DIVERGED_DTOL - The norm of the function has increased by a factor of divtol set with `SNESSetDivergenceTolerance()`
375 
376    Level: beginner
377 
378 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`, `SNESSetDivergenceTolerance()`
379 M*/
380 
381 /*MC
382    SNES_DIVERGED_FNORM_NAN - the 2-norm of the current function evaluation is not-a-number (NaN), this
383    is usually caused by a division of 0 by 0.
384 
385    Level: beginner
386 
387 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
388 M*/
389 
390 /*MC
391    SNES_DIVERGED_MAX_IT - SNESSolve() has reached the maximum number of iterations requested
392 
393    Level: beginner
394 
395 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
396 M*/
397 
398 /*MC
399    SNES_DIVERGED_LINE_SEARCH - The line search has failed. This only occurs for a `SNES` solvers that use a line search
400 
401    Level: beginner
402 
403 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`, `SNESLineSearch`
404 M*/
405 
406 /*MC
407    SNES_DIVERGED_LOCAL_MIN - the algorithm seems to have stagnated at a local minimum that is not zero.
408    See the manual page for `SNESConvergedReason` for more details
409 
410    Level: beginner
411 
412 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
413 M*/
414 
415 /*MC
416    SNES_CONERGED_ITERATING - this only occurs if `SNESGetConvergedReason()` is called during the `SNESSolve()`
417 
418    Level: beginner
419 
420 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
421 M*/
422 
423 PETSC_EXTERN PetscErrorCode SNESSetConvergenceTest(SNES, PetscErrorCode (*)(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *), void *, PetscErrorCode (*)(void *));
424 PETSC_EXTERN PetscErrorCode SNESConvergedDefault(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *);
425 PETSC_EXTERN PetscErrorCode SNESConvergedSkip(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *);
426 PETSC_EXTERN PetscErrorCode SNESConvergedCorrectPressure(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *);
427 PETSC_EXTERN PetscErrorCode SNESGetConvergedReason(SNES, SNESConvergedReason *);
428 PETSC_EXTERN PetscErrorCode SNESGetConvergedReasonString(SNES, const char **);
429 PETSC_EXTERN PetscErrorCode SNESSetConvergedReason(SNES, SNESConvergedReason);
430 
431 PETSC_DEPRECATED_FUNCTION(3, 5, 0, "SNESConvergedSkip()", ) static inline void SNESSkipConverged(void)
432 { /* never called */
433 }
434 #define SNESSkipConverged (SNESSkipConverged, SNESConvergedSkip)
435 
436 /*S
437   SNESInitialGuessFn - A prototype of a `SNES` compute initial guess function that would be passed to `SNESSetComputeInitialGuess()`
438 
439   Calling Sequence:
440 + snes  - `SNES` context
441 . u   - output vector to contain initial guess
442 - ctx - [optional] user-defined function context
443 
444   Level: beginner
445 
446 .seealso: [](ch_snes), `SNES`, `SNESSetComputeInitialGuess()`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`, `SNESFunctionFn`
447 S*/
448 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESInitialGuessFn)(SNES snes, Vec u, void *ctx);
449 
450 /*S
451   SNESFunctionFn - A prototype of a `SNES` evaluation function that would be passed to `SNESSetFunction()`
452 
453   Calling Sequence:
454 + snes  - `SNES` context
455 . u   - input vector
456 . F   - function vector
457 - ctx - [optional] user-defined function context
458 
459   Level: beginner
460 
461 .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`, `SNESNGSFn`
462 S*/
463 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESFunctionFn)(SNES snes, Vec u, Vec F, void *ctx);
464 
465 /*S
466   SNESObjectiveFn - A prototype of a `SNES` objective evaluation function that would be passed to `SNESSetObjective()`
467 
468   Calling Sequence:
469 + snes  - `SNES` context
470 . u   - input vector
471 . o   - output value
472 - ctx - [optional] user-defined function context
473 
474   Level: beginner
475 
476 .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`, `SNESNGSFn`
477 S*/
478 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESObjectiveFn)(SNES snes, Vec u, PetscReal *o, void *ctx);
479 
480 /*S
481   SNESJacobianFn - A prototype of a `SNES` Jacobian evaluation function that would be passed to `SNESSetJacobian()`
482 
483   Calling Sequence:
484 + snes   - the `SNES` context obtained from `SNESCreate()`
485 . u    - input vector
486 . Amat - (approximate) Jacobian matrix
487 . Pmat - matrix used to construct the preconditioner, often the same as `Amat`
488 - ctx  - [optional] user-defined context for matrix evaluation routine
489 
490   Level: beginner
491 
492 .seealso: [](ch_snes), `SNES`, `SNESSetJacobian()`, `SNESGetJacobian()`, `SNESFunctionFn`, `SNESNGSFn`
493 S*/
494 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESJacobianFn)(SNES snes, Vec u, Mat Amat, Mat Pmat, void *ctx);
495 
496 /*S
497   SNESNGSFn - A prototype of a `SNES` nonlinear Gauss-Seidel function that would be passed to `SNESSetNGS()`
498 
499   Calling Sequence:
500 + snes   - the `SNES` context obtained from `SNESCreate()`
501 . u    - the current solution, updated in place
502 . b    - the right-hand side vector (which may be `NULL`)
503 - ctx  - [optional] user-defined context for matrix evaluation routine
504 
505   Level: beginner
506 
507 .seealso: [](ch_snes), `SNES`, `SNESSetJacobian()`, `SNESGetJacobian()`, `SNESFunctionFn`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`
508 S*/
509 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESNGSFn)(SNES snes, Vec u, Vec b, void *ctx);
510 
511 /*S
512   SNESUpdateFn - A prototype of a `SNES` update function that would be passed to `SNESSetUpdate()`
513 
514   Calling Sequence:
515 + snes - `SNES` context
516 - step - the current iteration index
517 
518   Level: advanced
519 
520 .seealso: [](ch_snes), `SNES`, `SNESSetUpdate()`
521 S*/
522 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESUpdateFn)(SNES snes, PetscInt step);
523 
524 /* --------- Solving systems of nonlinear equations --------------- */
525 PETSC_EXTERN PetscErrorCode SNESSetFunction(SNES, Vec, SNESFunctionFn *, void *);
526 PETSC_EXTERN PetscErrorCode SNESGetFunction(SNES, Vec *, SNESFunctionFn **, void **);
527 PETSC_EXTERN PetscErrorCode SNESComputeFunction(SNES, Vec, Vec);
528 PETSC_EXTERN PetscErrorCode SNESComputeMFFunction(SNES, Vec, Vec);
529 PETSC_EXTERN PetscErrorCode SNESSetInitialFunction(SNES, Vec);
530 
531 PETSC_EXTERN PetscErrorCode SNESSetJacobian(SNES, Mat, Mat, SNESJacobianFn *, void *);
532 PETSC_EXTERN PetscErrorCode SNESGetJacobian(SNES, Mat *, Mat *, SNESJacobianFn **, void **);
533 PETSC_EXTERN SNESFunctionFn SNESObjectiveComputeFunctionDefaultFD;
534 PETSC_EXTERN SNESJacobianFn SNESComputeJacobianDefault;
535 PETSC_EXTERN SNESJacobianFn SNESComputeJacobianDefaultColor;
536 PETSC_EXTERN PetscErrorCode SNESPruneJacobianColor(SNES, Mat, Mat);
537 PETSC_EXTERN PetscErrorCode SNESSetComputeInitialGuess(SNES, SNESInitialGuessFn *, void *);
538 PETSC_EXTERN PetscErrorCode SNESSetPicard(SNES, Vec, SNESFunctionFn *, Mat, Mat, SNESJacobianFn *, void *);
539 PETSC_EXTERN PetscErrorCode SNESGetPicard(SNES, Vec *, SNESFunctionFn **, Mat *, Mat *, SNESJacobianFn **, void **);
540 PETSC_EXTERN SNESFunctionFn SNESPicardComputeFunction;
541 PETSC_EXTERN SNESFunctionFn SNESPicardComputeMFFunction;
542 PETSC_EXTERN SNESJacobianFn SNESPicardComputeJacobian;
543 
544 PETSC_EXTERN PetscErrorCode SNESSetObjective(SNES, SNESObjectiveFn *, void *);
545 PETSC_EXTERN PetscErrorCode SNESGetObjective(SNES, SNESObjectiveFn **, void **);
546 PETSC_EXTERN PetscErrorCode SNESComputeObjective(SNES, Vec, PetscReal *);
547 
548 PETSC_EXTERN PetscErrorCode SNESSetUpdate(SNES, SNESUpdateFn *);
549 
550 /*E
551    SNESNormSchedule - Frequency with which the norm is computed during a nonliner solve
552 
553    Values:
554 +   `SNES_NORM_DEFAULT`            - use the default behavior for the current `SNESType`
555 .   `SNES_NORM_NONE`               - avoid all norm computations
556 .   `SNES_NORM_ALWAYS`             - compute the norms whenever possible
557 .   `SNES_NORM_INITIAL_ONLY`       - compute the norm only when the algorithm starts
558 .   `SNES_NORM_FINAL_ONLY`         - compute the norm only when the algorithm finishes
559 -   `SNES_NORM_INITIAL_FINAL_ONLY` - compute the norm at the start and end of the algorithm
560 
561    Level: advanced
562 
563    Notes:
564    Support for these is highly dependent on the solver.
565 
566    Some options limit the convergence tests that can be used.
567 
568    The `SNES_NORM_NONE` option is most commonly used when the nonlinear solver is being used as a smoother, for example for `SNESFAS`
569 
570    This is primarily used to turn off extra norm and function computation
571    when the solvers are composed.
572 
573 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPSetNormType()`,
574           `KSPSetConvergenceTest()`, `KSPSetPCSide()`
575 E*/
576 typedef enum {
577   SNES_NORM_DEFAULT            = -1,
578   SNES_NORM_NONE               = 0,
579   SNES_NORM_ALWAYS             = 1,
580   SNES_NORM_INITIAL_ONLY       = 2,
581   SNES_NORM_FINAL_ONLY         = 3,
582   SNES_NORM_INITIAL_FINAL_ONLY = 4
583 } SNESNormSchedule;
584 PETSC_EXTERN const char *const *const SNESNormSchedules;
585 
586 /*MC
587    SNES_NORM_NONE - Don't compute function and its L2 norm when possible
588 
589    Level: advanced
590 
591    Note:
592    This is most useful for stationary solvers with a fixed number of iterations used as smoothers.
593 
594 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_DEFAULT`
595 M*/
596 
597 /*MC
598    SNES_NORM_ALWAYS - Compute the function and its L2 norm at each iteration.
599 
600    Level: advanced
601 
602    Note:
603    Most solvers will use this no matter what norm type is passed to them.
604 
605 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_NONE`
606 M*/
607 
608 /*MC
609    SNES_NORM_INITIAL_ONLY - Compute the function and its L2 at iteration 0, but do not update it.
610 
611    Level: advanced
612 
613    Notes:
614    This method is useful in composed methods, when a true solution might actually be found before `SNESSolve()` is called.
615    This option enables the solve to abort on the zeroth iteration if this is the case.
616 
617    For solvers that require the computation of the L2 norm of the function as part of the method, this merely cancels
618    the norm computation at the last iteration (if possible).
619 
620 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_FINAL_ONLY`, `SNES_NORM_INITIAL_FINAL_ONLY`
621 M*/
622 
623 /*MC
624    SNES_NORM_FINAL_ONLY - Compute the function and its L2 norm on only the final iteration.
625 
626    Level: advanced
627 
628    Note:
629    For solvers that require the computation of the L2 norm of the function as part of the method, behaves
630    exactly as `SNES_NORM_DEFAULT`.  This method is useful when the function is gotten after `SNESSolve()` and
631    used in subsequent computation for methods that do not need the norm computed during the rest of the
632    solution procedure.
633 
634 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_INITIAL_ONLY`, `SNES_NORM_INITIAL_FINAL_ONLY`
635 M*/
636 
637 /*MC
638    SNES_NORM_INITIAL_FINAL_ONLY - Compute the function and its L2 norm on only the initial and final iterations.
639 
640    Level: advanced
641 
642    Note:
643    This method combines the benefits of `SNES_NORM_INITIAL_ONLY` and `SNES_NORM_FINAL_ONLY`.
644 
645 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_SNES_NORM_INITIAL_ONLY`, `SNES_NORM_FINAL_ONLY`
646 M*/
647 
648 PETSC_EXTERN PetscErrorCode SNESSetNormSchedule(SNES, SNESNormSchedule);
649 PETSC_EXTERN PetscErrorCode SNESGetNormSchedule(SNES, SNESNormSchedule *);
650 PETSC_EXTERN PetscErrorCode SNESSetFunctionNorm(SNES, PetscReal);
651 PETSC_EXTERN PetscErrorCode SNESGetFunctionNorm(SNES, PetscReal *);
652 PETSC_EXTERN PetscErrorCode SNESGetUpdateNorm(SNES, PetscReal *);
653 PETSC_EXTERN PetscErrorCode SNESGetSolutionNorm(SNES, PetscReal *);
654 
655 /*E
656    SNESFunctionType - Type of function computed
657 
658    Values:
659 +  `SNES_FUNCTION_DEFAULT`          - the default behavior for the current `SNESType`
660 .  `SNES_FUNCTION_UNPRECONDITIONED` - the original function provided
661 -  `SNES_FUNCTION_PRECONDITIONED`   - the modification of the function by the preconditioner
662 
663    Level: advanced
664 
665    Note:
666    Support for these is dependent on the solver.
667 
668 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPSetNormType()`,
669           `KSPSetConvergenceTest()`, `KSPSetPCSide()`
670 E*/
671 typedef enum {
672   SNES_FUNCTION_DEFAULT          = -1,
673   SNES_FUNCTION_UNPRECONDITIONED = 0,
674   SNES_FUNCTION_PRECONDITIONED   = 1
675 } SNESFunctionType;
676 PETSC_EXTERN const char *const *const SNESFunctionTypes;
677 
678 PETSC_EXTERN PetscErrorCode SNESSetFunctionType(SNES, SNESFunctionType);
679 PETSC_EXTERN PetscErrorCode SNESGetFunctionType(SNES, SNESFunctionType *);
680 
681 PETSC_EXTERN PetscErrorCode SNESSetNGS(SNES, SNESNGSFn *, void *);
682 PETSC_EXTERN PetscErrorCode SNESGetNGS(SNES, SNESNGSFn **, void **);
683 PETSC_EXTERN PetscErrorCode SNESComputeNGS(SNES, Vec, Vec);
684 
685 PETSC_EXTERN PetscErrorCode SNESNGSSetSweeps(SNES, PetscInt);
686 PETSC_EXTERN PetscErrorCode SNESNGSGetSweeps(SNES, PetscInt *);
687 PETSC_EXTERN PetscErrorCode SNESNGSSetTolerances(SNES, PetscReal, PetscReal, PetscReal, PetscInt);
688 PETSC_EXTERN PetscErrorCode SNESNGSGetTolerances(SNES, PetscReal *, PetscReal *, PetscReal *, PetscInt *);
689 
690 PETSC_EXTERN PetscErrorCode SNESSetAlwaysComputesFinalResidual(SNES, PetscBool);
691 PETSC_EXTERN PetscErrorCode SNESGetAlwaysComputesFinalResidual(SNES, PetscBool *);
692 
693 PETSC_EXTERN PetscErrorCode SNESShellGetContext(SNES, void *);
694 PETSC_EXTERN PetscErrorCode SNESShellSetContext(SNES, void *);
695 PETSC_EXTERN PetscErrorCode SNESShellSetSolve(SNES, PetscErrorCode (*)(SNES, Vec));
696 
697 /* --------- Routines specifically for line search methods --------------- */
698 
699 /*S
700    SNESLineSearch - Abstract PETSc object that manages line-search operations for nonlinear solvers
701 
702    Level: beginner
703 
704 .seealso: [](ch_snes), `SNESLineSearchType`, `SNESLineSearchCreate()`, `SNESLineSearchSetType()`, `SNES`
705 S*/
706 typedef struct _p_LineSearch *SNESLineSearch;
707 
708 /*J
709    SNESLineSearchType - String with the name of a PETSc line search method `SNESLineSearch`. Provides all the linesearches for the nonlinear solvers, `SNES`,
710                         in PETSc.
711 
712    Values:
713 +  `SNESLINESEARCHBASIC`   - (or equivalently `SNESLINESEARCHNONE`) Simple damping line search, defaults to using the full Newton step
714 .  `SNESLINESEARCHBT`      - Backtracking line search over the L2 norm of the function
715 .  `SNESLINESEARCHL2`      - Secant line search over the L2 norm of the function
716 .  `SNESLINESEARCHCP`      - Critical point secant line search assuming $F(x) = \nabla G(x)$ for some unknown $G(x)$
717 .  `SNESLINESEARCHNLEQERR` - Affine-covariant error-oriented linesearch
718 -  `SNESLINESEARCHSHELL`   - User provided `SNESLineSearch` implementation
719 
720    Level: beginner
721 
722    Note:
723    Use `SNESLineSearchSetType()` or the options database key `-snes_linesearch_type` to set
724    the specific line search algorithm to use with a given `SNES` object. Not all `SNESType` can utilize a line search.
725 
726 .seealso: [](ch_snes), `SNESLineSearch`, `SNESLineSearchSetType()`, `SNES`
727 J*/
728 typedef const char *SNESLineSearchType;
729 #define SNESLINESEARCHBT        "bt"
730 #define SNESLINESEARCHNLEQERR   "nleqerr"
731 #define SNESLINESEARCHBASIC     "basic"
732 #define SNESLINESEARCHNONE      "none"
733 #define SNESLINESEARCHL2        "l2"
734 #define SNESLINESEARCHCP        "cp"
735 #define SNESLINESEARCHSHELL     "shell"
736 #define SNESLINESEARCHNCGLINEAR "ncglinear"
737 #define SNESLINESEARCHBISECTION "bisection"
738 
739 PETSC_EXTERN PetscFunctionList SNESList;
740 PETSC_EXTERN PetscClassId      SNESLINESEARCH_CLASSID;
741 PETSC_EXTERN PetscFunctionList SNESLineSearchList;
742 
743 #define SNES_LINESEARCH_ORDER_LINEAR    1
744 #define SNES_LINESEARCH_ORDER_QUADRATIC 2
745 #define SNES_LINESEARCH_ORDER_CUBIC     3
746 
747 /*S
748   SNESLineSearchVIProjectFn - A prototype of a `SNES` function that projects a vector onto the VI bounds, passed to `SNESLineSearchSetVIFunctions()`
749 
750   Calling Sequence:
751 + snes  - `SNES` context
752 - u     - the vector to project to the bounds
753 
754   Level: advanced
755 
756   Note:
757   The deprecated `SNESLineSearchVIProjectFunc` still works as a replacement for `SNESLineSearchVIProjectFn` *.
758 
759 .seealso: [](ch_snes), `SNES`, `SNESLineSearch`
760 S*/
761 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchVIProjectFn)(SNES snes, Vec u);
762 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchVIProjectFn *SNESLineSearchVIProjectFunc; // deprecated
763 
764 /*S
765   SNESLineSearchVIProjectFn - A prototype of a `SNES` function that computes the norm of the active set variables in a vector in a VI solve,
766   passed to `SNESLineSearchSetVIFunctions()`
767 
768   Calling Sequence:
769 + snes  - `SNES` context
770 . f     - the vector to compute the norm of
771 . u     - the current solution, entries that are on the VI bounds are ignored
772 - fnorm - the resulting norm
773 
774   Level: advanced
775 
776   Note:
777   The deprecated `SNESLineSearchVINormFunc` still works as a replacement for `SNESLineSearchVINormFn` *.
778 
779 .seealso: [](ch_snes), `SNES`, `SNESLineSearch`
780 S*/
781 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchVINormFn)(SNES snes, Vec f, Vec u, PetscReal *fnorm);
782 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchVINormFn *SNESLineSearchVINormFunc; // deprecated
783 
784 /*S
785   SNESLineSearchVIDirDerivFn - A prototype of a `SNES` function that computes the directional derivative considering the VI bounds, passed to `SNESLineSearchSetVIFunctions()`
786 
787   Calling Sequence:
788 + snes  - `SNES` context
789 . f     - the function vector to compute the directional derivative with
790 . u     - the current solution, entries that are on the VI bounds are ignored
791 . y     - the direction to compute the directional derivative
792 - fty   - the resulting directional derivative
793 
794   Level: advanced
795 
796 .seealso: [](ch_snes), `SNES`, `SNESLineSearch`, `SNESLineSearchVIProjectFn`, `SNESLineSearchVIProjectFn`, `SNESLineSearchSetVIFunctions()`, `SNESLineSearchGetVIFunctions()`
797 S*/
798 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchVIDirDerivFn)(SNES snes, Vec f, Vec u, Vec y, PetscScalar *fty);
799 
800 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchApplyFn)(SNESLineSearch);
801 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchApplyFn *SNESLineSearchApplyFunc; // deprecated
802 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchShellApplyFn)(SNESLineSearch, void *);
803 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchShellApplyFn *SNESLineSearchUserFunc; // deprecated
804 
805 PETSC_EXTERN PetscErrorCode SNESLineSearchCreate(MPI_Comm, SNESLineSearch *);
806 PETSC_EXTERN PetscErrorCode SNESLineSearchReset(SNESLineSearch);
807 PETSC_EXTERN PetscErrorCode SNESLineSearchView(SNESLineSearch, PetscViewer);
808 PETSC_EXTERN PetscErrorCode SNESLineSearchDestroy(SNESLineSearch *);
809 PETSC_EXTERN PetscErrorCode SNESLineSearchGetType(SNESLineSearch, SNESLineSearchType *);
810 PETSC_EXTERN PetscErrorCode SNESLineSearchSetType(SNESLineSearch, SNESLineSearchType);
811 PETSC_EXTERN PetscErrorCode SNESLineSearchSetFromOptions(SNESLineSearch);
812 PETSC_EXTERN PetscErrorCode SNESLineSearchSetFunction(SNESLineSearch, PetscErrorCode (*)(SNES, Vec, Vec));
813 PETSC_EXTERN PetscErrorCode SNESLineSearchSetUp(SNESLineSearch);
814 PETSC_EXTERN PetscErrorCode SNESLineSearchApply(SNESLineSearch, Vec, Vec, PetscReal *, Vec);
815 PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheck(SNESLineSearch, Vec, Vec, PetscBool *);
816 PETSC_EXTERN PetscErrorCode SNESLineSearchPostCheck(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *);
817 PETSC_EXTERN PetscErrorCode SNESLineSearchSetWorkVecs(SNESLineSearch, PetscInt);
818 
819 /* set the functions for precheck and postcheck */
820 
821 PETSC_EXTERN PetscErrorCode SNESLineSearchSetPreCheck(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, Vec, Vec, PetscBool *, void *), void *ctx);
822 PETSC_EXTERN PetscErrorCode SNESLineSearchSetPostCheck(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void *ctx);
823 
824 PETSC_EXTERN PetscErrorCode SNESLineSearchGetPreCheck(SNESLineSearch, PetscErrorCode (**)(SNESLineSearch, Vec, Vec, PetscBool *, void *), void **ctx);
825 PETSC_EXTERN PetscErrorCode SNESLineSearchGetPostCheck(SNESLineSearch, PetscErrorCode (**)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void **ctx);
826 
827 /* set the functions for VI-specific line search operations */
828 
829 PETSC_EXTERN PetscErrorCode SNESLineSearchSetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn *, SNESLineSearchVINormFn *, SNESLineSearchVIDirDerivFn *);
830 PETSC_EXTERN PetscErrorCode SNESLineSearchGetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn **, SNESLineSearchVINormFn **, SNESLineSearchVIDirDerivFn **);
831 
832 /* pointers to the associated SNES in order to be able to get the function evaluation out */
833 PETSC_EXTERN PetscErrorCode SNESLineSearchSetSNES(SNESLineSearch, SNES);
834 PETSC_EXTERN PetscErrorCode SNESLineSearchGetSNES(SNESLineSearch, SNES *);
835 
836 /* set and get the parameters and vectors */
837 PETSC_EXTERN PetscErrorCode SNESLineSearchGetTolerances(SNESLineSearch, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscInt *);
838 PETSC_EXTERN PetscErrorCode SNESLineSearchSetTolerances(SNESLineSearch, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal, PetscInt);
839 
840 PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch, Vec, Vec, PetscBool *, void *);
841 
842 PETSC_EXTERN PetscErrorCode SNESLineSearchGetLambda(SNESLineSearch, PetscReal *);
843 PETSC_EXTERN PetscErrorCode SNESLineSearchSetLambda(SNESLineSearch, PetscReal);
844 
845 PETSC_EXTERN PetscErrorCode SNESLineSearchGetDamping(SNESLineSearch, PetscReal *);
846 PETSC_EXTERN PetscErrorCode SNESLineSearchSetDamping(SNESLineSearch, PetscReal);
847 
848 PETSC_EXTERN PetscErrorCode SNESLineSearchGetOrder(SNESLineSearch, PetscInt *);
849 PETSC_EXTERN PetscErrorCode SNESLineSearchSetOrder(SNESLineSearch, PetscInt);
850 
851 /*E
852     SNESLineSearchReason - indication if the line search has succeeded or failed and why
853 
854   Values:
855 +  `SNES_LINESEARCH_SUCCEEDED`       - the line search succeeded
856 .  `SNES_LINESEARCH_FAILED_NANORINF` - a not a number of infinity appeared in the computions
857 .  `SNES_LINESEARCH_FAILED_DOMAIN`   - the function was evaluated outside of its domain, see `SNESSetFunctionDomainError()` and `SNESSetJacobianDomainError()`
858 .  `SNES_LINESEARCH_FAILED_REDUCT`   - the linear search failed to get the requested decrease in its norm or objective
859 .  `SNES_LINESEARCH_FAILED_USER`     - used by `SNESLINESEARCHNLEQERR` to indicate the user changed the search direction inappropriately
860 -  `SNES_LINESEARCH_FAILED_FUNCTION` - indicates the maximum number of function evaluations allowed has been surpassed, `SNESConvergedReason` is also
861                                        set to `SNES_DIVERGED_FUNCTION_COUNT`
862 
863    Level: intermediate
864 
865    Developer Note:
866    Some of these reasons overlap with values of `SNESConvergedReason`
867 
868 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPConvergedReason`, `SNESSetConvergenceTest()`,
869           `SNESSetFunctionDomainError()` and `SNESSetJacobianDomainError()`
870 E*/
871 typedef enum {
872   SNES_LINESEARCH_SUCCEEDED,
873   SNES_LINESEARCH_FAILED_NANORINF,
874   SNES_LINESEARCH_FAILED_DOMAIN,
875   SNES_LINESEARCH_FAILED_REDUCT, /* INSUFFICIENT REDUCTION */
876   SNES_LINESEARCH_FAILED_USER,
877   SNES_LINESEARCH_FAILED_FUNCTION
878 } SNESLineSearchReason;
879 
880 PETSC_EXTERN PetscErrorCode SNESLineSearchGetReason(SNESLineSearch, SNESLineSearchReason *);
881 PETSC_EXTERN PetscErrorCode SNESLineSearchSetReason(SNESLineSearch, SNESLineSearchReason);
882 
883 PETSC_EXTERN PetscErrorCode SNESLineSearchGetVecs(SNESLineSearch, Vec *, Vec *, Vec *, Vec *, Vec *);
884 PETSC_EXTERN PetscErrorCode SNESLineSearchSetVecs(SNESLineSearch, Vec, Vec, Vec, Vec, Vec);
885 
886 PETSC_EXTERN PetscErrorCode SNESLineSearchGetNorms(SNESLineSearch, PetscReal *, PetscReal *, PetscReal *);
887 PETSC_EXTERN PetscErrorCode SNESLineSearchSetNorms(SNESLineSearch, PetscReal, PetscReal, PetscReal);
888 PETSC_EXTERN PetscErrorCode SNESLineSearchComputeNorms(SNESLineSearch);
889 PETSC_EXTERN PetscErrorCode SNESLineSearchSetComputeNorms(SNESLineSearch, PetscBool);
890 
891 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitor(SNESLineSearch);
892 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSet(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, void *), void *, PetscCtxDestroyFn *);
893 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSetFromOptions(SNESLineSearch, const char[], const char[], const char[], PetscErrorCode (*)(SNESLineSearch, PetscViewerAndFormat *), PetscErrorCode (*)(SNESLineSearch, PetscViewerAndFormat *));
894 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorCancel(SNESLineSearch);
895 PETSC_EXTERN PetscErrorCode SNESLineSearchSetDefaultMonitor(SNESLineSearch, PetscViewer);
896 PETSC_EXTERN PetscErrorCode SNESLineSearchGetDefaultMonitor(SNESLineSearch, PetscViewer *);
897 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSolutionUpdate(SNESLineSearch, PetscViewerAndFormat *);
898 
899 PETSC_EXTERN PetscErrorCode SNESLineSearchAppendOptionsPrefix(SNESLineSearch, const char[]);
900 PETSC_EXTERN PetscErrorCode SNESLineSearchGetOptionsPrefix(SNESLineSearch, const char *[]);
901 
902 /* Shell interface functions */
903 PETSC_EXTERN PetscErrorCode SNESLineSearchShellSetApply(SNESLineSearch, SNESLineSearchShellApplyFn, void *);
904 PETSC_EXTERN PetscErrorCode SNESLineSearchShellGetApply(SNESLineSearch, SNESLineSearchShellApplyFn **, void **);
905 
906 PETSC_DEPRECATED_FUNCTION(3, 21, 0, "SNESLinesearchShellSetApply()", ) static inline PetscErrorCode SNESLineSearchShellSetUserFunc(SNESLineSearch ls, SNESLineSearchUserFunc f, void *ctx)
907 {
908   return SNESLineSearchShellSetApply(ls, f, ctx);
909 }
910 
911 PETSC_DEPRECATED_FUNCTION(3, 21, 0, "SNESLinesearchShellGetApply()", ) static inline PetscErrorCode SNESLineSearchShellGetUserFunc(SNESLineSearch ls, SNESLineSearchUserFunc *f, void **ctx)
912 {
913   return SNESLineSearchShellGetApply(ls, f, ctx);
914 }
915 
916 /* BT interface functions */
917 PETSC_EXTERN PetscErrorCode SNESLineSearchBTSetAlpha(SNESLineSearch, PetscReal);
918 PETSC_EXTERN PetscErrorCode SNESLineSearchBTGetAlpha(SNESLineSearch, PetscReal *);
919 
920 /*register line search types */
921 PETSC_EXTERN PetscErrorCode SNESLineSearchRegister(const char[], PetscErrorCode (*)(SNESLineSearch));
922 
923 /* Routines for VI solver */
924 PETSC_EXTERN PetscErrorCode SNESVISetVariableBounds(SNES, Vec, Vec);
925 PETSC_EXTERN PetscErrorCode SNESVIGetVariableBounds(SNES, Vec *, Vec *);
926 PETSC_EXTERN PetscErrorCode SNESVISetComputeVariableBounds(SNES, PetscErrorCode (*)(SNES, Vec, Vec));
927 PETSC_EXTERN PetscErrorCode SNESVIGetInactiveSet(SNES, IS *);
928 PETSC_EXTERN PetscErrorCode SNESVIGetActiveSetIS(SNES, Vec, Vec, IS *);
929 PETSC_EXTERN PetscErrorCode SNESVIComputeInactiveSetFnorm(SNES, Vec, Vec, PetscReal *);
930 PETSC_EXTERN PetscErrorCode SNESVIComputeInactiveSetFtY(SNES, Vec, Vec, Vec, PetscScalar *);
931 PETSC_EXTERN PetscErrorCode SNESVISetRedundancyCheck(SNES, PetscErrorCode (*)(SNES, IS, IS *, void *), void *);
932 PETSC_EXTERN PetscErrorCode SNESVIComputeMeritFunction(Vec, PetscReal *, PetscReal *);
933 PETSC_EXTERN PetscErrorCode SNESVIComputeFunction(SNES, Vec, Vec, void *);
934 PETSC_EXTERN PetscErrorCode DMSetVI(DM, IS);
935 PETSC_EXTERN PetscErrorCode DMDestroyVI(DM);
936 
937 PETSC_EXTERN PetscErrorCode SNESTestLocalMin(SNES);
938 
939 /* Should this routine be private? */
940 PETSC_EXTERN PetscErrorCode SNESComputeJacobian(SNES, Vec, Mat, Mat);
941 PETSC_EXTERN PetscErrorCode SNESTestJacobian(SNES);
942 PETSC_EXTERN PetscErrorCode SNESTestFunction(SNES);
943 
944 PETSC_EXTERN PetscErrorCode SNESSetDM(SNES, DM);
945 PETSC_EXTERN PetscErrorCode SNESGetDM(SNES, DM *);
946 PETSC_EXTERN PetscErrorCode SNESSetNPC(SNES, SNES);
947 PETSC_EXTERN PetscErrorCode SNESGetNPC(SNES, SNES *);
948 PETSC_EXTERN PetscErrorCode SNESHasNPC(SNES, PetscBool *);
949 PETSC_EXTERN PetscErrorCode SNESApplyNPC(SNES, Vec, Vec, Vec);
950 PETSC_EXTERN PetscErrorCode SNESGetNPCFunction(SNES, Vec, PetscReal *);
951 PETSC_EXTERN PetscErrorCode SNESComputeFunctionDefaultNPC(SNES, Vec, Vec);
952 PETSC_EXTERN PetscErrorCode SNESSetNPCSide(SNES, PCSide);
953 PETSC_EXTERN PetscErrorCode SNESGetNPCSide(SNES, PCSide *);
954 PETSC_EXTERN PetscErrorCode SNESSetLineSearch(SNES, SNESLineSearch);
955 PETSC_EXTERN PetscErrorCode SNESGetLineSearch(SNES, SNESLineSearch *);
956 
957 PETSC_DEPRECATED_FUNCTION(3, 4, 0, "SNESGetLineSearch()", ) static inline PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *ls)
958 {
959   return SNESGetLineSearch(snes, ls);
960 }
961 PETSC_DEPRECATED_FUNCTION(3, 4, 0, "SNESSetLineSearch()", ) static inline PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch ls)
962 {
963   return SNESSetLineSearch(snes, ls);
964 }
965 
966 PETSC_EXTERN PetscErrorCode SNESSetUpMatrices(SNES);
967 PETSC_EXTERN PetscErrorCode DMSNESSetFunction(DM, SNESFunctionFn *, void *);
968 PETSC_EXTERN PetscErrorCode DMSNESGetFunction(DM, SNESFunctionFn **, void **);
969 PETSC_EXTERN PetscErrorCode DMSNESSetFunctionContextDestroy(DM, PetscCtxDestroyFn *);
970 PETSC_EXTERN PetscErrorCode DMSNESSetMFFunction(DM, SNESFunctionFn *, void *);
971 PETSC_EXTERN PetscErrorCode DMSNESSetNGS(DM, SNESNGSFn *, void *);
972 PETSC_EXTERN PetscErrorCode DMSNESGetNGS(DM, SNESNGSFn **, void **);
973 PETSC_EXTERN PetscErrorCode DMSNESSetJacobian(DM, SNESJacobianFn *, void *);
974 PETSC_EXTERN PetscErrorCode DMSNESGetJacobian(DM, SNESJacobianFn **, void **);
975 PETSC_EXTERN PetscErrorCode DMSNESSetJacobianContextDestroy(DM, PetscCtxDestroyFn *);
976 PETSC_EXTERN PetscErrorCode DMSNESSetPicard(DM, SNESFunctionFn *, SNESJacobianFn *, void *);
977 PETSC_EXTERN PetscErrorCode DMSNESGetPicard(DM, SNESFunctionFn **, SNESJacobianFn **, void **);
978 PETSC_EXTERN PetscErrorCode DMSNESSetObjective(DM, SNESObjectiveFn *, void *);
979 PETSC_EXTERN PetscErrorCode DMSNESGetObjective(DM, SNESObjectiveFn **, void **);
980 PETSC_EXTERN PetscErrorCode DMCopyDMSNES(DM, DM);
981 
982 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESFunctionFn)(DMDALocalInfo *, void *, void *, void *);
983 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESJacobianFn)(DMDALocalInfo *, void *, Mat, Mat, void *);
984 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESObjectiveFn)(DMDALocalInfo *, void *, PetscReal *, void *);
985 
986 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESFunctionVecFn)(DMDALocalInfo *, Vec, Vec, void *);
987 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESJacobianVecFn)(DMDALocalInfo *, Vec, Mat, Mat, void *);
988 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESObjectiveVecFn)(DMDALocalInfo *, Vec, PetscReal *, void *);
989 
990 PETSC_EXTERN PetscErrorCode DMDASNESSetFunctionLocal(DM, InsertMode, DMDASNESFunctionFn *, void *);
991 PETSC_EXTERN PetscErrorCode DMDASNESSetJacobianLocal(DM, DMDASNESJacobianFn *, void *);
992 PETSC_EXTERN PetscErrorCode DMDASNESSetObjectiveLocal(DM, DMDASNESObjectiveFn *, void *);
993 PETSC_EXTERN PetscErrorCode DMDASNESSetPicardLocal(DM, InsertMode, DMDASNESFunctionFn *, DMDASNESJacobianFn, void *);
994 
995 PETSC_EXTERN PetscErrorCode DMDASNESSetFunctionLocalVec(DM, InsertMode, DMDASNESFunctionVecFn *, void *);
996 PETSC_EXTERN PetscErrorCode DMDASNESSetJacobianLocalVec(DM, DMDASNESJacobianVecFn *, void *);
997 PETSC_EXTERN PetscErrorCode DMDASNESSetObjectiveLocalVec(DM, DMDASNESObjectiveVecFn *, void *);
998 
999 PETSC_EXTERN PetscErrorCode DMSNESSetBoundaryLocal(DM, PetscErrorCode (*)(DM, Vec, void *), void *);
1000 PETSC_EXTERN PetscErrorCode DMSNESSetObjectiveLocal(DM, PetscErrorCode (*)(DM, Vec, PetscReal *, void *), void *);
1001 PETSC_EXTERN PetscErrorCode DMSNESSetFunctionLocal(DM, PetscErrorCode (*)(DM, Vec, Vec, void *), void *);
1002 PETSC_EXTERN PetscErrorCode DMSNESSetJacobianLocal(DM, PetscErrorCode (*)(DM, Vec, Mat, Mat, void *), void *);
1003 PETSC_EXTERN PetscErrorCode DMSNESGetBoundaryLocal(DM, PetscErrorCode (**)(DM, Vec, void *), void **);
1004 PETSC_EXTERN PetscErrorCode DMSNESGetObjectiveLocal(DM, PetscErrorCode (**)(DM, Vec, PetscReal *, void *), void **);
1005 PETSC_EXTERN PetscErrorCode DMSNESGetFunctionLocal(DM, PetscErrorCode (**)(DM, Vec, Vec, void *), void **);
1006 PETSC_EXTERN PetscErrorCode DMSNESGetJacobianLocal(DM, PetscErrorCode (**)(DM, Vec, Mat, Mat, void *), void **);
1007 
1008 /* Routines for Multiblock solver */
1009 PETSC_EXTERN PetscErrorCode SNESMultiblockSetFields(SNES, const char[], PetscInt, const PetscInt *);
1010 PETSC_EXTERN PetscErrorCode SNESMultiblockSetIS(SNES, const char[], IS);
1011 PETSC_EXTERN PetscErrorCode SNESMultiblockSetBlockSize(SNES, PetscInt);
1012 PETSC_EXTERN PetscErrorCode SNESMultiblockSetType(SNES, PCCompositeType);
1013 PETSC_EXTERN PetscErrorCode SNESMultiblockGetSubSNES(SNES, PetscInt *, SNES *[]);
1014 
1015 /*J
1016    SNESMSType - String with the name of a PETSc `SNESMS` method.
1017 
1018    Level: intermediate
1019 
1020 .seealso: [](ch_snes), `SNESMS`, `SNESMSGetType()`, `SNESMSSetType()`, `SNES`
1021 J*/
1022 typedef const char *SNESMSType;
1023 #define SNESMSM62       "m62"
1024 #define SNESMSEULER     "euler"
1025 #define SNESMSJAMESON83 "jameson83"
1026 #define SNESMSVLTP11    "vltp11"
1027 #define SNESMSVLTP21    "vltp21"
1028 #define SNESMSVLTP31    "vltp31"
1029 #define SNESMSVLTP41    "vltp41"
1030 #define SNESMSVLTP51    "vltp51"
1031 #define SNESMSVLTP61    "vltp61"
1032 
1033 PETSC_EXTERN PetscErrorCode SNESMSRegister(SNESMSType, PetscInt, PetscInt, PetscReal, const PetscReal[], const PetscReal[], const PetscReal[]);
1034 PETSC_EXTERN PetscErrorCode SNESMSRegisterAll(void);
1035 PETSC_EXTERN PetscErrorCode SNESMSGetType(SNES, SNESMSType *);
1036 PETSC_EXTERN PetscErrorCode SNESMSSetType(SNES, SNESMSType);
1037 PETSC_EXTERN PetscErrorCode SNESMSGetDamping(SNES, PetscReal *);
1038 PETSC_EXTERN PetscErrorCode SNESMSSetDamping(SNES, PetscReal);
1039 PETSC_EXTERN PetscErrorCode SNESMSFinalizePackage(void);
1040 PETSC_EXTERN PetscErrorCode SNESMSInitializePackage(void);
1041 PETSC_EXTERN PetscErrorCode SNESMSRegisterDestroy(void);
1042 
1043 /*MC
1044    SNESNGMRESRestartType - the restart approach used by `SNESNGMRES`
1045 
1046   Values:
1047 +   `SNES_NGMRES_RESTART_NONE`       - never restart
1048 .   `SNES_NGMRES_RESTART_DIFFERENCE` - restart based upon difference criteria
1049 -   `SNES_NGMRES_RESTART_PERIODIC`   - restart after a fixed number of iterations
1050 
1051   Options Database Keys:
1052 + -snes_ngmres_restart_type <difference,periodic,none> - set the restart type
1053 - -snes_ngmres_restart <30>                            - sets the number of iterations before restart for periodic
1054 
1055    Level: intermediate
1056 
1057 .seealso: `SNES, `SNESNGMRES`, `SNESNGMRESSetSelectType()`, `SNESNGMRESGetSelectType()`, `SNESNGMRESSetRestartType()`,
1058           `SNESNGMRESGetRestartType()`, `SNESNGMRESSelectType`
1059 M*/
1060 typedef enum {
1061   SNES_NGMRES_RESTART_NONE       = 0,
1062   SNES_NGMRES_RESTART_PERIODIC   = 1,
1063   SNES_NGMRES_RESTART_DIFFERENCE = 2
1064 } SNESNGMRESRestartType;
1065 PETSC_EXTERN const char *const SNESNGMRESRestartTypes[];
1066 
1067 /*MC
1068    SNESNGMRESSelectType - the approach used by `SNESNGMRES` to determine how the candidate solution and
1069   combined solution are used to create the next iterate.
1070 
1071    Values:
1072 +   `SNES_NGMRES_SELECT_NONE`       - choose the combined solution all the time
1073 .   `SNES_NGMRES_SELECT_DIFFERENCE` - choose based upon the selection criteria
1074 -   `SNES_NGMRES_SELECT_LINESEARCH` - choose based upon line search combination
1075 
1076   Options Database Key:
1077 . -snes_ngmres_select_type<difference,none,linesearch> - select type
1078 
1079    Level: intermediate
1080 
1081 .seealso: `SNES, `SNESNGMRES`, `SNESNGMRESSetSelectType()`, `SNESNGMRESGetSelectType()`, `SNESNGMRESSetRestartType()`,
1082           `SNESNGMRESGetRestartType()`, `SNESNGMRESRestartType`
1083 M*/
1084 typedef enum {
1085   SNES_NGMRES_SELECT_NONE       = 0,
1086   SNES_NGMRES_SELECT_DIFFERENCE = 1,
1087   SNES_NGMRES_SELECT_LINESEARCH = 2
1088 } SNESNGMRESSelectType;
1089 PETSC_EXTERN const char *const SNESNGMRESSelectTypes[];
1090 
1091 PETSC_EXTERN PetscErrorCode SNESNGMRESSetRestartType(SNES, SNESNGMRESRestartType);
1092 PETSC_EXTERN PetscErrorCode SNESNGMRESSetSelectType(SNES, SNESNGMRESSelectType);
1093 PETSC_EXTERN PetscErrorCode SNESNGMRESSetRestartFmRise(SNES, PetscBool);
1094 PETSC_EXTERN PetscErrorCode SNESNGMRESGetRestartFmRise(SNES, PetscBool *);
1095 
1096 /*MC
1097    SNESNCGType - the conjugate update approach for `SNESNCG`
1098 
1099    Values:
1100 +   `SNES_NCG_FR`  - Fletcher-Reeves update
1101 .   `SNES_NCG_PRP` - Polak-Ribiere-Polyak update, the default and the only one that tolerates generalized search directions
1102 .   `SNES_NCG_HS`  - Hestenes-Steifel update
1103 .   `SNES_NCG_DY`  - Dai-Yuan update
1104 -   `SNES_NCG_CD`  - Conjugate Descent update
1105 
1106   Options Database Key:
1107 . -snes_ncg_type<fr,prp,hs,dy,cd> - select type
1108 
1109    Level: intermediate
1110 
1111 .seealso: `SNES, `SNESNCG`, `SNESNCGSetType()`
1112 M*/
1113 typedef enum {
1114   SNES_NCG_FR  = 0,
1115   SNES_NCG_PRP = 1,
1116   SNES_NCG_HS  = 2,
1117   SNES_NCG_DY  = 3,
1118   SNES_NCG_CD  = 4
1119 } SNESNCGType;
1120 PETSC_EXTERN const char *const SNESNCGTypes[];
1121 
1122 PETSC_EXTERN PetscErrorCode SNESNCGSetType(SNES, SNESNCGType);
1123 
1124 /*MC
1125    SNESQNScaleType - the scaling type used by `SNESQN`
1126 
1127    Values:
1128 +   `SNES_QN_SCALE_NONE`     - don't scale the problem
1129 .   `SNES_QN_SCALE_SCALAR`   - use Shanno scaling
1130 .   `SNES_QN_SCALE_DIAGONAL` - scale with a diagonalized BFGS formula (see Gilbert and Lemarechal 1989), available
1131 -   `SNES_QN_SCALE_JACOBIAN` - scale by solving a linear system coming from the Jacobian you provided with `SNESSetJacobian()`
1132                                computed at the first iteration of `SNESQN` and at ever restart.
1133 
1134     Options Database Key:
1135 . -snes_qn_scale_type <diagonal,none,scalar,jacobian> - Scaling type
1136 
1137    Level: intermediate
1138 
1139 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNType`, `SNESQNSetType()`, `SNESQNSetRestartType()`, `SNESQNRestartType`
1140 M*/
1141 typedef enum {
1142   SNES_QN_SCALE_DEFAULT  = 0,
1143   SNES_QN_SCALE_NONE     = 1,
1144   SNES_QN_SCALE_SCALAR   = 2,
1145   SNES_QN_SCALE_DIAGONAL = 3,
1146   SNES_QN_SCALE_JACOBIAN = 4
1147 } SNESQNScaleType;
1148 PETSC_EXTERN const char *const SNESQNScaleTypes[];
1149 
1150 /*MC
1151    SNESQNRestartType - the restart approached used by `SNESQN`
1152 
1153    Values:
1154 +   `SNES_QN_RESTART_NONE`     - never restart
1155 .   `SNES_QN_RESTART_POWELL`   - restart based upon descent criteria
1156 -   `SNES_QN_RESTART_PERIODIC` - restart after a fixed number of iterations
1157 
1158   Options Database Keys:
1159 + -snes_qn_restart_type <powell,periodic,none> - set the restart type
1160 - -snes_qn_m <m>                               - sets the number of stored updates and the restart period for periodic
1161 
1162    Level: intermediate
1163 
1164 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNType`, `SNESQNSetType()`, `SNESQNSetRestartType()`, `SNESQNScaleType`
1165 M*/
1166 typedef enum {
1167   SNES_QN_RESTART_DEFAULT  = 0,
1168   SNES_QN_RESTART_NONE     = 1,
1169   SNES_QN_RESTART_POWELL   = 2,
1170   SNES_QN_RESTART_PERIODIC = 3
1171 } SNESQNRestartType;
1172 PETSC_EXTERN const char *const SNESQNRestartTypes[];
1173 
1174 /*MC
1175    SNESQNType - the type used by `SNESQN`
1176 
1177   Values:
1178 +   `SNES_QN_LBFGS`      - LBFGS variant
1179 .   `SNES_QN_BROYDEN`    - Broyden variant
1180 -   `SNES_QN_BADBROYDEN` - Bad Broyden variant
1181 
1182   Options Database Key:
1183 . -snes_qn_type <lbfgs,broyden,badbroyden> - quasi-Newton type
1184 
1185    Level: intermediate
1186 
1187 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNSetType()`, `SNESQNScaleType`, `SNESQNRestartType`, `SNESQNSetRestartType()`
1188 M*/
1189 typedef enum {
1190   SNES_QN_LBFGS      = 0,
1191   SNES_QN_BROYDEN    = 1,
1192   SNES_QN_BADBROYDEN = 2
1193 } SNESQNType;
1194 PETSC_EXTERN const char *const SNESQNTypes[];
1195 
1196 PETSC_EXTERN PetscErrorCode SNESQNSetType(SNES, SNESQNType);
1197 PETSC_EXTERN PetscErrorCode SNESQNSetScaleType(SNES, SNESQNScaleType);
1198 PETSC_EXTERN PetscErrorCode SNESQNSetRestartType(SNES, SNESQNRestartType);
1199 
1200 PETSC_EXTERN PetscErrorCode SNESNASMGetType(SNES, PCASMType *);
1201 PETSC_EXTERN PetscErrorCode SNESNASMSetType(SNES, PCASMType);
1202 PETSC_EXTERN PetscErrorCode SNESNASMGetSubdomains(SNES, PetscInt *, SNES *[], VecScatter *[], VecScatter *[], VecScatter *[]);
1203 PETSC_EXTERN PetscErrorCode SNESNASMSetSubdomains(SNES, PetscInt, SNES[], VecScatter[], VecScatter[], VecScatter[]);
1204 PETSC_EXTERN PetscErrorCode SNESNASMSetDamping(SNES, PetscReal);
1205 PETSC_EXTERN PetscErrorCode SNESNASMGetDamping(SNES, PetscReal *);
1206 PETSC_EXTERN PetscErrorCode SNESNASMGetSubdomainVecs(SNES, PetscInt *, Vec *[], Vec *[], Vec *[], Vec *[]);
1207 PETSC_EXTERN PetscErrorCode SNESNASMSetComputeFinalJacobian(SNES, PetscBool);
1208 PETSC_EXTERN PetscErrorCode SNESNASMGetSNES(SNES, PetscInt, SNES *);
1209 PETSC_EXTERN PetscErrorCode SNESNASMGetNumber(SNES, PetscInt *);
1210 PETSC_EXTERN PetscErrorCode SNESNASMSetWeight(SNES, Vec);
1211 
1212 /*E
1213   SNESCompositeType - Determines how two or more preconditioners are composed with the `SNESType` of `SNESCOMPOSITE`
1214 
1215   Values:
1216 + `SNES_COMPOSITE_ADDITIVE`        - results from application of all preconditioners are added together
1217 . `SNES_COMPOSITE_MULTIPLICATIVE`  - preconditioners are applied sequentially to the residual freshly
1218                                      computed after the previous preconditioner application
1219 - `SNES_COMPOSITE_ADDITIVEOPTIMAL` - uses a linear combination of the solutions obtained with each preconditioner that approximately minimize the function
1220                                      value at the new iteration.
1221 
1222    Level: beginner
1223 
1224 .seealso: [](sec_pc), `PCCOMPOSITE`, `PCFIELDSPLIT`, `PC`, `PCCompositeSetType()`, `PCCompositeType`
1225 E*/
1226 typedef enum {
1227   SNES_COMPOSITE_ADDITIVE,
1228   SNES_COMPOSITE_MULTIPLICATIVE,
1229   SNES_COMPOSITE_ADDITIVEOPTIMAL
1230 } SNESCompositeType;
1231 PETSC_EXTERN const char *const SNESCompositeTypes[];
1232 
1233 PETSC_EXTERN PetscErrorCode SNESCompositeSetType(SNES, SNESCompositeType);
1234 PETSC_EXTERN PetscErrorCode SNESCompositeAddSNES(SNES, SNESType);
1235 PETSC_EXTERN PetscErrorCode SNESCompositeGetSNES(SNES, PetscInt, SNES *);
1236 PETSC_EXTERN PetscErrorCode SNESCompositeGetNumber(SNES, PetscInt *);
1237 PETSC_EXTERN PetscErrorCode SNESCompositeSetDamping(SNES, PetscInt, PetscReal);
1238 
1239 PETSC_EXTERN PetscErrorCode SNESPatchSetDiscretisationInfo(SNES, PetscInt, DM *, PetscInt *, PetscInt *, const PetscInt **, const PetscInt *, PetscInt, const PetscInt *, PetscInt, const PetscInt *);
1240 PETSC_EXTERN PetscErrorCode SNESPatchSetComputeOperator(SNES, PetscErrorCode (*func)(PC, PetscInt, Vec, Mat, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *);
1241 PETSC_EXTERN PetscErrorCode SNESPatchSetComputeFunction(SNES, PetscErrorCode (*func)(PC, PetscInt, Vec, Vec, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *);
1242 PETSC_EXTERN PetscErrorCode SNESPatchSetConstructType(SNES, PCPatchConstructType, PetscErrorCode (*func)(PC, PetscInt *, IS **, IS *, void *), void *);
1243 PETSC_EXTERN PetscErrorCode SNESPatchSetCellNumbering(SNES, PetscSection);
1244 
1245 /*E
1246     SNESFASType - Determines the type of nonlinear multigrid method that is run.
1247 
1248    Values:
1249 +  `SNES_FAS_MULTIPLICATIVE` (default) - traditional V or W cycle as determined by `SNESFASSetCycles()`
1250 .  `SNES_FAS_ADDITIVE`                 - additive FAS cycle
1251 .  `SNES_FAS_FULL`                     - full FAS cycle
1252 -  `SNES_FAS_KASKADE`                  - Kaskade FAS cycle
1253 
1254    Level: beginner
1255 
1256 .seealso: [](ch_snes), `SNESFAS`, `PCMGSetType()`, `PCMGType`
1257 E*/
1258 typedef enum {
1259   SNES_FAS_MULTIPLICATIVE,
1260   SNES_FAS_ADDITIVE,
1261   SNES_FAS_FULL,
1262   SNES_FAS_KASKADE
1263 } SNESFASType;
1264 PETSC_EXTERN const char *const SNESFASTypes[];
1265 
1266 /* called on the finest level FAS instance*/
1267 PETSC_EXTERN PetscErrorCode SNESFASSetType(SNES, SNESFASType);
1268 PETSC_EXTERN PetscErrorCode SNESFASGetType(SNES, SNESFASType *);
1269 PETSC_EXTERN PetscErrorCode SNESFASSetLevels(SNES, PetscInt, MPI_Comm *);
1270 PETSC_EXTERN PetscErrorCode SNESFASGetLevels(SNES, PetscInt *);
1271 PETSC_EXTERN PetscErrorCode SNESFASGetCycleSNES(SNES, PetscInt, SNES *);
1272 PETSC_EXTERN PetscErrorCode SNESFASSetNumberSmoothUp(SNES, PetscInt);
1273 PETSC_EXTERN PetscErrorCode SNESFASSetNumberSmoothDown(SNES, PetscInt);
1274 PETSC_EXTERN PetscErrorCode SNESFASSetCycles(SNES, PetscInt);
1275 PETSC_EXTERN PetscErrorCode SNESFASSetMonitor(SNES, PetscViewerAndFormat *, PetscBool);
1276 PETSC_EXTERN PetscErrorCode SNESFASSetLog(SNES, PetscBool);
1277 
1278 PETSC_EXTERN PetscErrorCode SNESFASSetGalerkin(SNES, PetscBool);
1279 PETSC_EXTERN PetscErrorCode SNESFASGetGalerkin(SNES, PetscBool *);
1280 PETSC_EXTERN PetscErrorCode SNESFASGalerkinFunctionDefault(SNES, Vec, Vec, void *);
1281 
1282 /* called on any level -- "Cycle" FAS instance */
1283 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmoother(SNES, SNES *);
1284 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmootherUp(SNES, SNES *);
1285 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmootherDown(SNES, SNES *);
1286 PETSC_EXTERN PetscErrorCode SNESFASCycleGetCorrection(SNES, SNES *);
1287 PETSC_EXTERN PetscErrorCode SNESFASCycleGetInterpolation(SNES, Mat *);
1288 PETSC_EXTERN PetscErrorCode SNESFASCycleGetRestriction(SNES, Mat *);
1289 PETSC_EXTERN PetscErrorCode SNESFASCycleGetInjection(SNES, Mat *);
1290 PETSC_EXTERN PetscErrorCode SNESFASCycleGetRScale(SNES, Vec *);
1291 PETSC_EXTERN PetscErrorCode SNESFASCycleSetCycles(SNES, PetscInt);
1292 PETSC_EXTERN PetscErrorCode SNESFASCycleIsFine(SNES, PetscBool *);
1293 
1294 /* called on the (outer) finest level FAS to set/get parameters on any level instance */
1295 PETSC_EXTERN PetscErrorCode SNESFASSetInterpolation(SNES, PetscInt, Mat);
1296 PETSC_EXTERN PetscErrorCode SNESFASGetInterpolation(SNES, PetscInt, Mat *);
1297 PETSC_EXTERN PetscErrorCode SNESFASSetRestriction(SNES, PetscInt, Mat);
1298 PETSC_EXTERN PetscErrorCode SNESFASGetRestriction(SNES, PetscInt, Mat *);
1299 PETSC_EXTERN PetscErrorCode SNESFASSetInjection(SNES, PetscInt, Mat);
1300 PETSC_EXTERN PetscErrorCode SNESFASGetInjection(SNES, PetscInt, Mat *);
1301 PETSC_EXTERN PetscErrorCode SNESFASSetRScale(SNES, PetscInt, Vec);
1302 PETSC_EXTERN PetscErrorCode SNESFASGetRScale(SNES, PetscInt, Vec *);
1303 PETSC_EXTERN PetscErrorCode SNESFASSetContinuation(SNES, PetscBool);
1304 
1305 PETSC_EXTERN PetscErrorCode SNESFASGetSmoother(SNES, PetscInt, SNES *);
1306 PETSC_EXTERN PetscErrorCode SNESFASGetSmootherUp(SNES, PetscInt, SNES *);
1307 PETSC_EXTERN PetscErrorCode SNESFASGetSmootherDown(SNES, PetscInt, SNES *);
1308 PETSC_EXTERN PetscErrorCode SNESFASGetCoarseSolve(SNES, SNES *);
1309 
1310 /* parameters for full FAS */
1311 PETSC_EXTERN PetscErrorCode SNESFASFullSetDownSweep(SNES, PetscBool);
1312 PETSC_EXTERN PetscErrorCode SNESFASCreateCoarseVec(SNES, Vec *);
1313 PETSC_EXTERN PetscErrorCode SNESFASRestrict(SNES, Vec, Vec);
1314 PETSC_EXTERN PetscErrorCode SNESFASFullSetTotal(SNES, PetscBool);
1315 PETSC_EXTERN PetscErrorCode SNESFASFullGetTotal(SNES, PetscBool *);
1316 
1317 PETSC_EXTERN PetscErrorCode DMPlexSetSNESVariableBounds(DM, SNES);
1318 PETSC_EXTERN PetscErrorCode DMSNESCheckDiscretization(SNES, DM, PetscReal, Vec, PetscReal, PetscReal[]);
1319 PETSC_EXTERN PetscErrorCode DMSNESCheckResidual(SNES, DM, Vec, PetscReal, PetscReal *);
1320 PETSC_EXTERN PetscErrorCode DMSNESCheckJacobian(SNES, DM, Vec, PetscReal, PetscBool *, PetscReal *);
1321 PETSC_EXTERN PetscErrorCode DMSNESCheckFromOptions(SNES, Vec);
1322 PETSC_EXTERN PetscErrorCode DMSNESComputeJacobianAction(DM, Vec, Vec, Vec, void *);
1323 PETSC_EXTERN PetscErrorCode DMSNESCreateJacobianMF(DM, Vec, void *, Mat *);
1324 
1325 PETSC_EXTERN PetscErrorCode SNESNewtonALSetFunction(SNES, SNESFunctionFn *, void *ctx);
1326 PETSC_EXTERN PetscErrorCode SNESNewtonALGetFunction(SNES, SNESFunctionFn **, void **ctx);
1327 PETSC_EXTERN PetscErrorCode SNESNewtonALComputeFunction(SNES, Vec, Vec);
1328 PETSC_EXTERN PetscErrorCode SNESNewtonALGetLoadParameter(SNES, PetscReal *);
1329 
1330 /*MC
1331    SNESNewtonALCorrectionType - the approach used by `SNESNEWTONAL` to determine
1332    the correction to the current increment. While the exact correction satisfies
1333    the constraint surface at every iteration, it also requires solving a quadratic
1334    equation which may not have real roots. Conversely, the normal correction is more
1335    efficient and always yields a real correction and is the default.
1336 
1337    Values:
1338 +   `SNES_NEWTONAL_CORRECTION_EXACT` - choose the correction which exactly satisfies the constraint
1339 -   `SNES_NEWTONAL_CORRECTION_NORMAL` - choose the correction in the updated normal hyper-surface to the constraint surface
1340 
1341    Options Database Key:
1342 . -snes_newtonal_correction_type <exact> - select type from <exact,normal>
1343 
1344    Level: intermediate
1345 
1346 .seealso: `SNES`, `SNESNEWTONAL`, `SNESNewtonALSetCorrectionType()`
1347 M*/
1348 typedef enum {
1349   SNES_NEWTONAL_CORRECTION_EXACT  = 0,
1350   SNES_NEWTONAL_CORRECTION_NORMAL = 1,
1351 } SNESNewtonALCorrectionType;
1352 PETSC_EXTERN const char *const SNESNewtonALCorrectionTypes[];
1353 
1354 PETSC_EXTERN PetscErrorCode SNESNewtonALSetCorrectionType(SNES, SNESNewtonALCorrectionType);
1355