xref: /petsc/include/petscsnes.h (revision 7a5338279d92d13360d231b9bd26d284f35eaa49)
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 #include <petscdrawtypes.h>
239 PETSC_EXTERN PetscErrorCode SNESMonitorLGRange(SNES, PetscInt, PetscReal, void *);
240 
241 PETSC_EXTERN PetscErrorCode SNESSetApplicationContext(SNES, void *);
242 PETSC_EXTERN PetscErrorCode SNESGetApplicationContext(SNES, void *);
243 PETSC_EXTERN PetscErrorCode SNESSetComputeApplicationContext(SNES, PetscErrorCode (*)(SNES, void **), PetscCtxDestroyFn *);
244 
245 PETSC_EXTERN PetscErrorCode SNESPythonSetType(SNES, const char[]);
246 PETSC_EXTERN PetscErrorCode SNESPythonGetType(SNES, const char *[]);
247 
248 PETSC_EXTERN PetscErrorCode SNESSetFunctionDomainError(SNES);
249 PETSC_EXTERN PetscErrorCode SNESGetFunctionDomainError(SNES, PetscBool *);
250 PETSC_EXTERN PetscErrorCode SNESGetJacobianDomainError(SNES, PetscBool *);
251 PETSC_EXTERN PetscErrorCode SNESSetJacobianDomainError(SNES);
252 PETSC_EXTERN PetscErrorCode SNESSetCheckJacobianDomainError(SNES, PetscBool);
253 PETSC_EXTERN PetscErrorCode SNESGetCheckJacobianDomainError(SNES, PetscBool *);
254 
255 #define SNES_CONVERGED_TR_DELTA_DEPRECATED SNES_CONVERGED_TR_DELTA PETSC_DEPRECATED_ENUM(3, 12, 0, "SNES_DIVERGED_TR_DELTA", )
256 /*E
257     SNESConvergedReason - reason a `SNESSolve()` was determined to have converged or diverged
258 
259    Values:
260 +  `SNES_CONVERGED_FNORM_ABS`      - 2-norm(F) <= abstol
261 .  `SNES_CONVERGED_FNORM_RELATIVE` - 2-norm(F) <= rtol*2-norm(F(x_0)) where x_0 is the initial guess
262 .  `SNES_CONVERGED_SNORM_RELATIVE` - The 2-norm of the last step <= stol * 2-norm(x) where x is the current
263 .  `SNES_CONVERGED_USER`           - The user has indicated convergence for an arbitrary reason
264 .  `SNES_DIVERGED_FUNCTION_COUNT`  - The user provided function has been called more times than the maximum set in `SNESSetTolerances()`
265 .  `SNES_DIVERGED_DTOL`            - The norm of the function has increased by a factor of divtol set with `SNESSetDivergenceTolerance()`
266 .  `SNES_DIVERGED_FNORM_NAN`       - the 2-norm of the current function evaluation is not-a-number (NaN), this
267                                      is usually caused by a division of 0 by 0.
268 .  `SNES_DIVERGED_MAX_IT`          - `SNESSolve()` has reached the maximum number of iterations requested
269 .  `SNES_DIVERGED_LINE_SEARCH`     - The line search has failed. This only occurs for `SNES` solvers that use a line search
270 .  `SNES_DIVERGED_LOCAL_MIN`       - the algorithm seems to have stagnated at a local minimum that is not zero.
271 .  `SNES_DIVERGED_USER`            - The user has indicated divergence for an arbitrary reason
272 -  `SNES_CONVERGED_ITERATING       - this only occurs if `SNESGetConvergedReason()` is called during the `SNESSolve()`
273 
274    Level: beginner
275 
276     Notes:
277    The two most common reasons for divergence are an incorrectly coded or computed Jacobian or failure or lack of convergence in the linear system
278    (in this case we recommend
279    testing with `-pc_type lu` to eliminate the linear solver as the cause of the problem).
280 
281    `SNES_DIVERGED_LOCAL_MIN` can only occur when using a `SNES` solver that uses a line search (`SNESLineSearch`).
282    The line search wants to minimize Q(alpha) = 1/2 || F(x + alpha s) ||^2_2  this occurs
283    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
284    you get Q'(alpha) = -F(x)^T F'(x)^(-1)^T F'(x+alpha s)F(x+alpha s); when alpha = 0
285    Q'(0) = - ||F(x)||^2_2 which is always NEGATIVE if F'(x) is invertible. This means the Newton
286    direction is a descent direction and the line search should succeed if alpha is small enough.
287 
288    If F'(x) is NOT invertible AND F'(x)^T F(x) = 0 then Q'(0) = 0 and the Newton direction
289    is NOT a descent direction so the line search will fail. All one can do at this point
290    is change the initial guess and try again.
291 
292    An alternative explanation: Newton's method can be regarded as replacing the function with
293    its linear approximation and minimizing the 2-norm of that. That is F(x+s) approx F(x) + F'(x)s
294    so we minimize || F(x) + F'(x) s ||^2_2; do this using Least Squares. If F'(x) is invertible then
295    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
296    exists a nontrivial (that is F'(x)s != 0) solution to the equation and this direction is
297    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)
298    = - (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
299    and F'(x)^T F'(x) has no negative eigenvalues Q'(0) < 0 so s is a descent direction and the line
300    search should succeed for small enough alpha.
301 
302    Note that this RARELY happens in practice. Far more likely the linear system is not being solved
303    (well enough?) or the Jacobian is wrong.
304 
305    `SNES_DIVERGED_MAX_IT` means that the solver reached the maximum number of iterations without satisfying any
306    convergence criteria. `SNES_CONVERGED_ITS` means that `SNESConvergedSkip()` was chosen as the convergence test;
307    thus the usual convergence criteria have not been checked and may or may not be satisfied.
308 
309 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPConvergedReason`, `SNESSetConvergenceTest()`, `SNESSetTolerances()`
310 E*/
311 typedef enum {                       /* converged */
312   SNES_CONVERGED_FNORM_ABS      = 2, /* ||F|| < atol */
313   SNES_CONVERGED_FNORM_RELATIVE = 3, /* ||F|| < rtol*||F_initial|| */
314   SNES_CONVERGED_SNORM_RELATIVE = 4, /* Newton computed step size small; || delta x || < stol || x ||*/
315   SNES_CONVERGED_ITS            = 5, /* maximum iterations reached */
316   SNES_BREAKOUT_INNER_ITER      = 6, /* Flag to break out of inner loop after checking custom convergence.
317                                         It is used in multi-phase flow when state changes */
318   SNES_CONVERGED_USER           = 7, /* The user has indicated convergence for an arbitrary reason */
319   /* diverged */
320   SNES_DIVERGED_FUNCTION_DOMAIN      = -1, /* the new x location passed the function is not in the domain of F */
321   SNES_DIVERGED_FUNCTION_COUNT       = -2,
322   SNES_DIVERGED_LINEAR_SOLVE         = -3, /* the linear solve failed */
323   SNES_DIVERGED_FNORM_NAN            = -4,
324   SNES_DIVERGED_MAX_IT               = -5,
325   SNES_DIVERGED_LINE_SEARCH          = -6,  /* the line search failed */
326   SNES_DIVERGED_INNER                = -7,  /* inner solve failed */
327   SNES_DIVERGED_LOCAL_MIN            = -8,  /* || J^T b || is small, implies converged to local minimum of F() */
328   SNES_DIVERGED_DTOL                 = -9,  /* || F || > divtol*||F_initial|| */
329   SNES_DIVERGED_JACOBIAN_DOMAIN      = -10, /* Jacobian calculation does not make sense */
330   SNES_DIVERGED_TR_DELTA             = -11,
331   SNES_CONVERGED_TR_DELTA_DEPRECATED = -11,
332   SNES_DIVERGED_USER                 = -12, /* The user has indicated divergence for an arbitrary reason */
333 
334   SNES_CONVERGED_ITERATING = 0
335 } SNESConvergedReason;
336 PETSC_EXTERN const char *const *SNESConvergedReasons;
337 
338 /*MC
339    SNES_CONVERGED_FNORM_ABS - 2-norm(F) <= abstol
340 
341    Level: beginner
342 
343 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
344 M*/
345 
346 /*MC
347    SNES_CONVERGED_FNORM_RELATIVE - 2-norm(F) <= rtol*2-norm(F(x_0)) where x_0 is the initial guess
348 
349    Level: beginner
350 
351 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
352 M*/
353 
354 /*MC
355   SNES_CONVERGED_SNORM_RELATIVE - The 2-norm of the last step <= stol * 2-norm(x) where x is the current
356   solution and stol is the 4th argument to `SNESSetTolerances()`
357 
358   Options Database Key:
359   -snes_stol <stol> - the step tolerance
360 
361    Level: beginner
362 
363 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
364 M*/
365 
366 /*MC
367    SNES_DIVERGED_FUNCTION_COUNT - The user provided function has been called more times then the final
368    argument to `SNESSetTolerances()`
369 
370    Level: beginner
371 
372 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
373 M*/
374 
375 /*MC
376    SNES_DIVERGED_DTOL - The norm of the function has increased by a factor of divtol set with `SNESSetDivergenceTolerance()`
377 
378    Level: beginner
379 
380 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`, `SNESSetDivergenceTolerance()`
381 M*/
382 
383 /*MC
384    SNES_DIVERGED_FNORM_NAN - the 2-norm of the current function evaluation is not-a-number (NaN), this
385    is usually caused by a division of 0 by 0.
386 
387    Level: beginner
388 
389 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
390 M*/
391 
392 /*MC
393    SNES_DIVERGED_MAX_IT - SNESSolve() has reached the maximum number of iterations requested
394 
395    Level: beginner
396 
397 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
398 M*/
399 
400 /*MC
401    SNES_DIVERGED_LINE_SEARCH - The line search has failed. This only occurs for a `SNES` solvers that use a line search
402 
403    Level: beginner
404 
405 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`, `SNESLineSearch`
406 M*/
407 
408 /*MC
409    SNES_DIVERGED_LOCAL_MIN - the algorithm seems to have stagnated at a local minimum that is not zero.
410    See the manual page for `SNESConvergedReason` for more details
411 
412    Level: beginner
413 
414 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
415 M*/
416 
417 /*MC
418    SNES_CONERGED_ITERATING - this only occurs if `SNESGetConvergedReason()` is called during the `SNESSolve()`
419 
420    Level: beginner
421 
422 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
423 M*/
424 
425 PETSC_EXTERN PetscErrorCode SNESSetConvergenceTest(SNES, PetscErrorCode (*)(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *), void *, PetscErrorCode (*)(void *));
426 PETSC_EXTERN PetscErrorCode SNESConvergedDefault(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *);
427 PETSC_EXTERN PetscErrorCode SNESConvergedSkip(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *);
428 PETSC_EXTERN PetscErrorCode SNESConvergedCorrectPressure(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *);
429 PETSC_EXTERN PetscErrorCode SNESGetConvergedReason(SNES, SNESConvergedReason *);
430 PETSC_EXTERN PetscErrorCode SNESGetConvergedReasonString(SNES, const char **);
431 PETSC_EXTERN PetscErrorCode SNESSetConvergedReason(SNES, SNESConvergedReason);
432 
433 PETSC_DEPRECATED_FUNCTION(3, 5, 0, "SNESConvergedSkip()", ) static inline void SNESSkipConverged(void)
434 { /* never called */
435 }
436 #define SNESSkipConverged (SNESSkipConverged, SNESConvergedSkip)
437 
438 /*S
439   SNESInitialGuessFn - A prototype of a `SNES` compute initial guess function that would be passed to `SNESSetComputeInitialGuess()`
440 
441   Calling Sequence:
442 + snes  - `SNES` context
443 . u   - output vector to contain initial guess
444 - ctx - [optional] user-defined function context
445 
446   Level: beginner
447 
448 .seealso: [](ch_snes), `SNES`, `SNESSetComputeInitialGuess()`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`, `SNESFunctionFn`
449 S*/
450 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESInitialGuessFn)(SNES snes, Vec u, void *ctx);
451 
452 /*S
453   SNESFunctionFn - A prototype of a `SNES` evaluation function that would be passed to `SNESSetFunction()`
454 
455   Calling Sequence:
456 + snes  - `SNES` context
457 . u   - input vector
458 . F   - function vector
459 - ctx - [optional] user-defined function context
460 
461   Level: beginner
462 
463 .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`, `SNESNGSFn`
464 S*/
465 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESFunctionFn)(SNES snes, Vec u, Vec F, void *ctx);
466 
467 /*S
468   SNESObjectiveFn - A prototype of a `SNES` objective evaluation function that would be passed to `SNESSetObjective()`
469 
470   Calling Sequence:
471 + snes  - `SNES` context
472 . u   - input vector
473 . o   - output value
474 - ctx - [optional] user-defined function context
475 
476   Level: beginner
477 
478 .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`, `SNESNGSFn`
479 S*/
480 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESObjectiveFn)(SNES snes, Vec u, PetscReal *o, void *ctx);
481 
482 /*S
483   SNESJacobianFn - A prototype of a `SNES` Jacobian evaluation function that would be passed to `SNESSetJacobian()`
484 
485   Calling Sequence:
486 + snes   - the `SNES` context obtained from `SNESCreate()`
487 . u    - input vector
488 . Amat - (approximate) Jacobian matrix
489 . Pmat - matrix used to construct the preconditioner, often the same as `Amat`
490 - ctx  - [optional] user-defined context for matrix evaluation routine
491 
492   Level: beginner
493 
494 .seealso: [](ch_snes), `SNES`, `SNESSetJacobian()`, `SNESGetJacobian()`, `SNESFunctionFn`, `SNESNGSFn`
495 S*/
496 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESJacobianFn)(SNES snes, Vec u, Mat Amat, Mat Pmat, void *ctx);
497 
498 /*S
499   SNESNGSFn - A prototype of a `SNES` nonlinear Gauss-Seidel function that would be passed to `SNESSetNGS()`
500 
501   Calling Sequence:
502 + snes   - the `SNES` context obtained from `SNESCreate()`
503 . u    - the current solution, updated in place
504 . b    - the right-hand side vector (which may be `NULL`)
505 - ctx  - [optional] user-defined context for matrix evaluation routine
506 
507   Level: beginner
508 
509 .seealso: [](ch_snes), `SNES`, `SNESSetJacobian()`, `SNESGetJacobian()`, `SNESFunctionFn`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESJacobianFn`
510 S*/
511 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESNGSFn)(SNES snes, Vec u, Vec b, void *ctx);
512 
513 /*S
514   SNESUpdateFn - A prototype of a `SNES` update function that would be passed to `SNESSetUpdate()`
515 
516   Calling Sequence:
517 + snes - `SNES` context
518 - step - the current iteration index
519 
520   Level: advanced
521 
522 .seealso: [](ch_snes), `SNES`, `SNESSetUpdate()`
523 S*/
524 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESUpdateFn)(SNES snes, PetscInt step);
525 
526 /* --------- Solving systems of nonlinear equations --------------- */
527 PETSC_EXTERN PetscErrorCode SNESSetFunction(SNES, Vec, SNESFunctionFn *, void *);
528 PETSC_EXTERN PetscErrorCode SNESGetFunction(SNES, Vec *, SNESFunctionFn **, void **);
529 PETSC_EXTERN PetscErrorCode SNESComputeFunction(SNES, Vec, Vec);
530 PETSC_EXTERN PetscErrorCode SNESComputeMFFunction(SNES, Vec, Vec);
531 PETSC_EXTERN PetscErrorCode SNESSetInitialFunction(SNES, Vec);
532 
533 PETSC_EXTERN PetscErrorCode SNESSetJacobian(SNES, Mat, Mat, SNESJacobianFn *, void *);
534 PETSC_EXTERN PetscErrorCode SNESGetJacobian(SNES, Mat *, Mat *, SNESJacobianFn **, void **);
535 PETSC_EXTERN SNESFunctionFn SNESObjectiveComputeFunctionDefaultFD;
536 PETSC_EXTERN SNESJacobianFn SNESComputeJacobianDefault;
537 PETSC_EXTERN SNESJacobianFn SNESComputeJacobianDefaultColor;
538 PETSC_EXTERN PetscErrorCode SNESPruneJacobianColor(SNES, Mat, Mat);
539 PETSC_EXTERN PetscErrorCode SNESSetComputeInitialGuess(SNES, SNESInitialGuessFn *, void *);
540 PETSC_EXTERN PetscErrorCode SNESSetPicard(SNES, Vec, SNESFunctionFn *, Mat, Mat, SNESJacobianFn *, void *);
541 PETSC_EXTERN PetscErrorCode SNESGetPicard(SNES, Vec *, SNESFunctionFn **, Mat *, Mat *, SNESJacobianFn **, void **);
542 PETSC_EXTERN SNESFunctionFn SNESPicardComputeFunction;
543 PETSC_EXTERN SNESFunctionFn SNESPicardComputeMFFunction;
544 PETSC_EXTERN SNESJacobianFn SNESPicardComputeJacobian;
545 
546 PETSC_EXTERN PetscErrorCode SNESSetObjective(SNES, SNESObjectiveFn *, void *);
547 PETSC_EXTERN PetscErrorCode SNESGetObjective(SNES, SNESObjectiveFn **, void **);
548 PETSC_EXTERN PetscErrorCode SNESComputeObjective(SNES, Vec, PetscReal *);
549 
550 PETSC_EXTERN PetscErrorCode SNESSetUpdate(SNES, SNESUpdateFn *);
551 
552 /*E
553    SNESNormSchedule - Frequency with which the norm is computed during a nonliner solve
554 
555    Values:
556 +   `SNES_NORM_DEFAULT`            - use the default behavior for the current `SNESType`
557 .   `SNES_NORM_NONE`               - avoid all norm computations
558 .   `SNES_NORM_ALWAYS`             - compute the norms whenever possible
559 .   `SNES_NORM_INITIAL_ONLY`       - compute the norm only when the algorithm starts
560 .   `SNES_NORM_FINAL_ONLY`         - compute the norm only when the algorithm finishes
561 -   `SNES_NORM_INITIAL_FINAL_ONLY` - compute the norm at the start and end of the algorithm
562 
563    Level: advanced
564 
565    Notes:
566    Support for these is highly dependent on the solver.
567 
568    Some options limit the convergence tests that can be used.
569 
570    The `SNES_NORM_NONE` option is most commonly used when the nonlinear solver is being used as a smoother, for example for `SNESFAS`
571 
572    This is primarily used to turn off extra norm and function computation
573    when the solvers are composed.
574 
575 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPSetNormType()`,
576           `KSPSetConvergenceTest()`, `KSPSetPCSide()`
577 E*/
578 typedef enum {
579   SNES_NORM_DEFAULT            = -1,
580   SNES_NORM_NONE               = 0,
581   SNES_NORM_ALWAYS             = 1,
582   SNES_NORM_INITIAL_ONLY       = 2,
583   SNES_NORM_FINAL_ONLY         = 3,
584   SNES_NORM_INITIAL_FINAL_ONLY = 4
585 } SNESNormSchedule;
586 PETSC_EXTERN const char *const *const SNESNormSchedules;
587 
588 /*MC
589    SNES_NORM_NONE - Don't compute function and its L2 norm when possible
590 
591    Level: advanced
592 
593    Note:
594    This is most useful for stationary solvers with a fixed number of iterations used as smoothers.
595 
596 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_DEFAULT`
597 M*/
598 
599 /*MC
600    SNES_NORM_ALWAYS - Compute the function and its L2 norm at each iteration.
601 
602    Level: advanced
603 
604    Note:
605    Most solvers will use this no matter what norm type is passed to them.
606 
607 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_NONE`
608 M*/
609 
610 /*MC
611    SNES_NORM_INITIAL_ONLY - Compute the function and its L2 at iteration 0, but do not update it.
612 
613    Level: advanced
614 
615    Notes:
616    This method is useful in composed methods, when a true solution might actually be found before `SNESSolve()` is called.
617    This option enables the solve to abort on the zeroth iteration if this is the case.
618 
619    For solvers that require the computation of the L2 norm of the function as part of the method, this merely cancels
620    the norm computation at the last iteration (if possible).
621 
622 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_FINAL_ONLY`, `SNES_NORM_INITIAL_FINAL_ONLY`
623 M*/
624 
625 /*MC
626    SNES_NORM_FINAL_ONLY - Compute the function and its L2 norm on only the final iteration.
627 
628    Level: advanced
629 
630    Note:
631    For solvers that require the computation of the L2 norm of the function as part of the method, behaves
632    exactly as `SNES_NORM_DEFAULT`.  This method is useful when the function is gotten after `SNESSolve()` and
633    used in subsequent computation for methods that do not need the norm computed during the rest of the
634    solution procedure.
635 
636 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_INITIAL_ONLY`, `SNES_NORM_INITIAL_FINAL_ONLY`
637 M*/
638 
639 /*MC
640    SNES_NORM_INITIAL_FINAL_ONLY - Compute the function and its L2 norm on only the initial and final iterations.
641 
642    Level: advanced
643 
644    Note:
645    This method combines the benefits of `SNES_NORM_INITIAL_ONLY` and `SNES_NORM_FINAL_ONLY`.
646 
647 .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_SNES_NORM_INITIAL_ONLY`, `SNES_NORM_FINAL_ONLY`
648 M*/
649 
650 PETSC_EXTERN PetscErrorCode SNESSetNormSchedule(SNES, SNESNormSchedule);
651 PETSC_EXTERN PetscErrorCode SNESGetNormSchedule(SNES, SNESNormSchedule *);
652 PETSC_EXTERN PetscErrorCode SNESSetFunctionNorm(SNES, PetscReal);
653 PETSC_EXTERN PetscErrorCode SNESGetFunctionNorm(SNES, PetscReal *);
654 PETSC_EXTERN PetscErrorCode SNESGetUpdateNorm(SNES, PetscReal *);
655 PETSC_EXTERN PetscErrorCode SNESGetSolutionNorm(SNES, PetscReal *);
656 
657 /*E
658    SNESFunctionType - Type of function computed
659 
660    Values:
661 +  `SNES_FUNCTION_DEFAULT`          - the default behavior for the current `SNESType`
662 .  `SNES_FUNCTION_UNPRECONDITIONED` - the original function provided
663 -  `SNES_FUNCTION_PRECONDITIONED`   - the modification of the function by the preconditioner
664 
665    Level: advanced
666 
667    Note:
668    Support for these is dependent on the solver.
669 
670 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPSetNormType()`,
671           `KSPSetConvergenceTest()`, `KSPSetPCSide()`
672 E*/
673 typedef enum {
674   SNES_FUNCTION_DEFAULT          = -1,
675   SNES_FUNCTION_UNPRECONDITIONED = 0,
676   SNES_FUNCTION_PRECONDITIONED   = 1
677 } SNESFunctionType;
678 PETSC_EXTERN const char *const *const SNESFunctionTypes;
679 
680 PETSC_EXTERN PetscErrorCode SNESSetFunctionType(SNES, SNESFunctionType);
681 PETSC_EXTERN PetscErrorCode SNESGetFunctionType(SNES, SNESFunctionType *);
682 
683 PETSC_EXTERN PetscErrorCode SNESSetNGS(SNES, SNESNGSFn *, void *);
684 PETSC_EXTERN PetscErrorCode SNESGetNGS(SNES, SNESNGSFn **, void **);
685 PETSC_EXTERN PetscErrorCode SNESComputeNGS(SNES, Vec, Vec);
686 
687 PETSC_EXTERN PetscErrorCode SNESNGSSetSweeps(SNES, PetscInt);
688 PETSC_EXTERN PetscErrorCode SNESNGSGetSweeps(SNES, PetscInt *);
689 PETSC_EXTERN PetscErrorCode SNESNGSSetTolerances(SNES, PetscReal, PetscReal, PetscReal, PetscInt);
690 PETSC_EXTERN PetscErrorCode SNESNGSGetTolerances(SNES, PetscReal *, PetscReal *, PetscReal *, PetscInt *);
691 
692 PETSC_EXTERN PetscErrorCode SNESSetAlwaysComputesFinalResidual(SNES, PetscBool);
693 PETSC_EXTERN PetscErrorCode SNESGetAlwaysComputesFinalResidual(SNES, PetscBool *);
694 
695 PETSC_EXTERN PetscErrorCode SNESShellGetContext(SNES, void *);
696 PETSC_EXTERN PetscErrorCode SNESShellSetContext(SNES, void *);
697 PETSC_EXTERN PetscErrorCode SNESShellSetSolve(SNES, PetscErrorCode (*)(SNES, Vec));
698 
699 /* --------- Routines specifically for line search methods --------------- */
700 
701 /*S
702    SNESLineSearch - Abstract PETSc object that manages line-search operations for nonlinear solvers
703 
704    Level: beginner
705 
706 .seealso: [](ch_snes), `SNESLineSearchType`, `SNESLineSearchCreate()`, `SNESLineSearchSetType()`, `SNES`
707 S*/
708 typedef struct _p_LineSearch *SNESLineSearch;
709 
710 /*J
711    SNESLineSearchType - String with the name of a PETSc line search method `SNESLineSearch`. Provides all the linesearches for the nonlinear solvers, `SNES`,
712                         in PETSc.
713 
714    Values:
715 +  `SNESLINESEARCHBASIC`   - (or equivalently `SNESLINESEARCHNONE`) Simple damping line search, defaults to using the full Newton step
716 .  `SNESLINESEARCHBT`      - Backtracking line search over the L2 norm of the function
717 .  `SNESLINESEARCHL2`      - Secant line search over the L2 norm of the function
718 .  `SNESLINESEARCHCP`      - Critical point secant line search assuming $F(x) = \nabla G(x)$ for some unknown $G(x)$
719 .  `SNESLINESEARCHNLEQERR` - Affine-covariant error-oriented linesearch
720 -  `SNESLINESEARCHSHELL`   - User provided `SNESLineSearch` implementation
721 
722    Level: beginner
723 
724    Note:
725    Use `SNESLineSearchSetType()` or the options database key `-snes_linesearch_type` to set
726    the specific line search algorithm to use with a given `SNES` object. Not all `SNESType` can utilize a line search.
727 
728 .seealso: [](ch_snes), `SNESLineSearch`, `SNESLineSearchSetType()`, `SNES`
729 J*/
730 typedef const char *SNESLineSearchType;
731 #define SNESLINESEARCHBT        "bt"
732 #define SNESLINESEARCHNLEQERR   "nleqerr"
733 #define SNESLINESEARCHBASIC     "basic"
734 #define SNESLINESEARCHNONE      "none"
735 #define SNESLINESEARCHL2        "l2"
736 #define SNESLINESEARCHCP        "cp"
737 #define SNESLINESEARCHSHELL     "shell"
738 #define SNESLINESEARCHNCGLINEAR "ncglinear"
739 #define SNESLINESEARCHBISECTION "bisection"
740 
741 PETSC_EXTERN PetscFunctionList SNESList;
742 PETSC_EXTERN PetscClassId      SNESLINESEARCH_CLASSID;
743 PETSC_EXTERN PetscFunctionList SNESLineSearchList;
744 
745 #define SNES_LINESEARCH_ORDER_LINEAR    1
746 #define SNES_LINESEARCH_ORDER_QUADRATIC 2
747 #define SNES_LINESEARCH_ORDER_CUBIC     3
748 
749 /*S
750   SNESLineSearchVIProjectFn - A prototype of a `SNES` function that projects a vector onto the VI bounds, passed to `SNESLineSearchSetVIFunctions()`
751 
752   Calling Sequence:
753 + snes  - `SNES` context
754 - u     - the vector to project to the bounds
755 
756   Level: advanced
757 
758   Note:
759   The deprecated `SNESLineSearchVIProjectFunc` still works as a replacement for `SNESLineSearchVIProjectFn` *.
760 
761 .seealso: [](ch_snes), `SNES`, `SNESLineSearch`
762 S*/
763 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchVIProjectFn)(SNES snes, Vec u);
764 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchVIProjectFn *SNESLineSearchVIProjectFunc; // deprecated
765 
766 /*S
767   SNESLineSearchVIProjectFn - A prototype of a `SNES` function that computes the norm of the active set variables in a vector in a VI solve,
768   passed to `SNESLineSearchSetVIFunctions()`
769 
770   Calling Sequence:
771 + snes  - `SNES` context
772 . f     - the vector to compute the norm of
773 . u     - the current solution, entries that are on the VI bounds are ignored
774 - fnorm - the resulting norm
775 
776   Level: advanced
777 
778   Note:
779   The deprecated `SNESLineSearchVINormFunc` still works as a replacement for `SNESLineSearchVINormFn` *.
780 
781 .seealso: [](ch_snes), `SNES`, `SNESLineSearch`
782 S*/
783 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchVINormFn)(SNES snes, Vec f, Vec u, PetscReal *fnorm);
784 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchVINormFn *SNESLineSearchVINormFunc; // deprecated
785 
786 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchApplyFn)(SNESLineSearch);
787 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchApplyFn *SNESLineSearchApplyFunc; // deprecated
788 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(SNESLineSearchShellApplyFn)(SNESLineSearch, void *);
789 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchShellApplyFn *SNESLineSearchUserFunc; // deprecated
790 
791 PETSC_EXTERN PetscErrorCode SNESLineSearchCreate(MPI_Comm, SNESLineSearch *);
792 PETSC_EXTERN PetscErrorCode SNESLineSearchReset(SNESLineSearch);
793 PETSC_EXTERN PetscErrorCode SNESLineSearchView(SNESLineSearch, PetscViewer);
794 PETSC_EXTERN PetscErrorCode SNESLineSearchDestroy(SNESLineSearch *);
795 PETSC_EXTERN PetscErrorCode SNESLineSearchGetType(SNESLineSearch, SNESLineSearchType *);
796 PETSC_EXTERN PetscErrorCode SNESLineSearchSetType(SNESLineSearch, SNESLineSearchType);
797 PETSC_EXTERN PetscErrorCode SNESLineSearchSetFromOptions(SNESLineSearch);
798 PETSC_EXTERN PetscErrorCode SNESLineSearchSetFunction(SNESLineSearch, PetscErrorCode (*)(SNES, Vec, Vec));
799 PETSC_EXTERN PetscErrorCode SNESLineSearchSetUp(SNESLineSearch);
800 PETSC_EXTERN PetscErrorCode SNESLineSearchApply(SNESLineSearch, Vec, Vec, PetscReal *, Vec);
801 PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheck(SNESLineSearch, Vec, Vec, PetscBool *);
802 PETSC_EXTERN PetscErrorCode SNESLineSearchPostCheck(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *);
803 PETSC_EXTERN PetscErrorCode SNESLineSearchSetWorkVecs(SNESLineSearch, PetscInt);
804 
805 /* set the functions for precheck and postcheck */
806 
807 PETSC_EXTERN PetscErrorCode SNESLineSearchSetPreCheck(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, Vec, Vec, PetscBool *, void *), void *ctx);
808 PETSC_EXTERN PetscErrorCode SNESLineSearchSetPostCheck(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void *ctx);
809 
810 PETSC_EXTERN PetscErrorCode SNESLineSearchGetPreCheck(SNESLineSearch, PetscErrorCode (**)(SNESLineSearch, Vec, Vec, PetscBool *, void *), void **ctx);
811 PETSC_EXTERN PetscErrorCode SNESLineSearchGetPostCheck(SNESLineSearch, PetscErrorCode (**)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void **ctx);
812 
813 /* set the functions for VI-specific line search operations */
814 
815 PETSC_EXTERN PetscErrorCode SNESLineSearchSetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn *, SNESLineSearchVINormFn *);
816 PETSC_EXTERN PetscErrorCode SNESLineSearchGetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn **, SNESLineSearchVINormFn **);
817 
818 /* pointers to the associated SNES in order to be able to get the function evaluation out */
819 PETSC_EXTERN PetscErrorCode SNESLineSearchSetSNES(SNESLineSearch, SNES);
820 PETSC_EXTERN PetscErrorCode SNESLineSearchGetSNES(SNESLineSearch, SNES *);
821 
822 /* set and get the parameters and vectors */
823 PETSC_EXTERN PetscErrorCode SNESLineSearchGetTolerances(SNESLineSearch, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscInt *);
824 PETSC_EXTERN PetscErrorCode SNESLineSearchSetTolerances(SNESLineSearch, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal, PetscInt);
825 
826 PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch, Vec, Vec, PetscBool *, void *);
827 
828 PETSC_EXTERN PetscErrorCode SNESLineSearchGetLambda(SNESLineSearch, PetscReal *);
829 PETSC_EXTERN PetscErrorCode SNESLineSearchSetLambda(SNESLineSearch, PetscReal);
830 
831 PETSC_EXTERN PetscErrorCode SNESLineSearchGetDamping(SNESLineSearch, PetscReal *);
832 PETSC_EXTERN PetscErrorCode SNESLineSearchSetDamping(SNESLineSearch, PetscReal);
833 
834 PETSC_EXTERN PetscErrorCode SNESLineSearchGetOrder(SNESLineSearch, PetscInt *order);
835 PETSC_EXTERN PetscErrorCode SNESLineSearchSetOrder(SNESLineSearch, PetscInt order);
836 
837 /*E
838     SNESLineSearchReason - indication if the line search has succeeded or failed and why
839 
840   Values:
841 +  `SNES_LINESEARCH_SUCCEEDED`       - the line search succeeded
842 .  `SNES_LINESEARCH_FAILED_NANORINF` - a not a number of infinity appeared in the computions
843 .  `SNES_LINESEARCH_FAILED_DOMAIN`   - the function was evaluated outside of its domain, see `SNESSetFunctionDomainError()` and `SNESSetJacobianDomainError()`
844 .  `SNES_LINESEARCH_FAILED_REDUCT`   - the linear search failed to get the requested decrease in its norm or objective
845 .  `SNES_LINESEARCH_FAILED_USER`     - used by `SNESLINESEARCHNLEQERR` to indicate the user changed the search direction inappropriately
846 -  `SNES_LINESEARCH_FAILED_FUNCTION` - indicates the maximum number of function evaluations allowed has been surpassed, `SNESConvergedReason` is also
847                                        set to `SNES_DIVERGED_FUNCTION_COUNT`
848 
849    Level: intermediate
850 
851    Developer Note:
852    Some of these reasons overlap with values of `SNESConvergedReason`
853 
854 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPConvergedReason`, `SNESSetConvergenceTest()`,
855           `SNESSetFunctionDomainError()` and `SNESSetJacobianDomainError()`
856 E*/
857 typedef enum {
858   SNES_LINESEARCH_SUCCEEDED,
859   SNES_LINESEARCH_FAILED_NANORINF,
860   SNES_LINESEARCH_FAILED_DOMAIN,
861   SNES_LINESEARCH_FAILED_REDUCT, /* INSUFFICIENT REDUCTION */
862   SNES_LINESEARCH_FAILED_USER,
863   SNES_LINESEARCH_FAILED_FUNCTION
864 } SNESLineSearchReason;
865 
866 PETSC_EXTERN PetscErrorCode SNESLineSearchGetReason(SNESLineSearch, SNESLineSearchReason *);
867 PETSC_EXTERN PetscErrorCode SNESLineSearchSetReason(SNESLineSearch, SNESLineSearchReason);
868 
869 PETSC_EXTERN PetscErrorCode SNESLineSearchGetVecs(SNESLineSearch, Vec *, Vec *, Vec *, Vec *, Vec *);
870 PETSC_EXTERN PetscErrorCode SNESLineSearchSetVecs(SNESLineSearch, Vec, Vec, Vec, Vec, Vec);
871 
872 PETSC_EXTERN PetscErrorCode SNESLineSearchGetNorms(SNESLineSearch, PetscReal *, PetscReal *, PetscReal *);
873 PETSC_EXTERN PetscErrorCode SNESLineSearchSetNorms(SNESLineSearch, PetscReal, PetscReal, PetscReal);
874 PETSC_EXTERN PetscErrorCode SNESLineSearchComputeNorms(SNESLineSearch);
875 PETSC_EXTERN PetscErrorCode SNESLineSearchSetComputeNorms(SNESLineSearch, PetscBool);
876 
877 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitor(SNESLineSearch);
878 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSet(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, void *), void *, PetscCtxDestroyFn *);
879 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSetFromOptions(SNESLineSearch, const char[], const char[], const char[], PetscErrorCode (*)(SNESLineSearch, PetscViewerAndFormat *), PetscErrorCode (*)(SNESLineSearch, PetscViewerAndFormat *));
880 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorCancel(SNESLineSearch);
881 PETSC_EXTERN PetscErrorCode SNESLineSearchSetDefaultMonitor(SNESLineSearch, PetscViewer);
882 PETSC_EXTERN PetscErrorCode SNESLineSearchGetDefaultMonitor(SNESLineSearch, PetscViewer *);
883 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSolutionUpdate(SNESLineSearch, PetscViewerAndFormat *);
884 
885 PETSC_EXTERN PetscErrorCode SNESLineSearchAppendOptionsPrefix(SNESLineSearch, const char prefix[]);
886 PETSC_EXTERN PetscErrorCode SNESLineSearchGetOptionsPrefix(SNESLineSearch, const char *prefix[]);
887 
888 /* Shell interface functions */
889 PETSC_EXTERN PetscErrorCode SNESLineSearchShellSetApply(SNESLineSearch, SNESLineSearchShellApplyFn, void *);
890 PETSC_EXTERN PetscErrorCode SNESLineSearchShellGetApply(SNESLineSearch, SNESLineSearchShellApplyFn **, void **);
891 
892 PETSC_DEPRECATED_FUNCTION(3, 21, 0, "SNESLinesearchShellSetApply()", ) static inline PetscErrorCode SNESLineSearchShellSetUserFunc(SNESLineSearch ls, SNESLineSearchUserFunc f, void *ctx)
893 {
894   return SNESLineSearchShellSetApply(ls, f, ctx);
895 }
896 
897 PETSC_DEPRECATED_FUNCTION(3, 21, 0, "SNESLinesearchShellGetApply()", ) static inline PetscErrorCode SNESLineSearchShellGetUserFunc(SNESLineSearch ls, SNESLineSearchUserFunc *f, void **ctx)
898 {
899   return SNESLineSearchShellGetApply(ls, f, ctx);
900 }
901 
902 /* BT interface functions */
903 PETSC_EXTERN PetscErrorCode SNESLineSearchBTSetAlpha(SNESLineSearch, PetscReal);
904 PETSC_EXTERN PetscErrorCode SNESLineSearchBTGetAlpha(SNESLineSearch, PetscReal *);
905 
906 /*register line search types */
907 PETSC_EXTERN PetscErrorCode SNESLineSearchRegister(const char[], PetscErrorCode (*)(SNESLineSearch));
908 
909 /* Routines for VI solver */
910 PETSC_EXTERN PetscErrorCode SNESVISetVariableBounds(SNES, Vec, Vec);
911 PETSC_EXTERN PetscErrorCode SNESVIGetVariableBounds(SNES, Vec *, Vec *);
912 PETSC_EXTERN PetscErrorCode SNESVISetComputeVariableBounds(SNES, PetscErrorCode (*)(SNES, Vec, Vec));
913 PETSC_EXTERN PetscErrorCode SNESVIGetInactiveSet(SNES, IS *);
914 PETSC_EXTERN PetscErrorCode SNESVIGetActiveSetIS(SNES, Vec, Vec, IS *);
915 PETSC_EXTERN PetscErrorCode SNESVIComputeInactiveSetFnorm(SNES, Vec, Vec, PetscReal *);
916 PETSC_EXTERN PetscErrorCode SNESVISetRedundancyCheck(SNES, PetscErrorCode (*)(SNES, IS, IS *, void *), void *);
917 PETSC_EXTERN PetscErrorCode SNESVIComputeMeritFunction(Vec, PetscReal *, PetscReal *);
918 PETSC_EXTERN PetscErrorCode SNESVIComputeFunction(SNES, Vec, Vec, void *);
919 PETSC_EXTERN PetscErrorCode DMSetVI(DM, IS);
920 PETSC_EXTERN PetscErrorCode DMDestroyVI(DM);
921 
922 PETSC_EXTERN PetscErrorCode SNESTestLocalMin(SNES);
923 
924 /* Should this routine be private? */
925 PETSC_EXTERN PetscErrorCode SNESComputeJacobian(SNES, Vec, Mat, Mat);
926 PETSC_EXTERN PetscErrorCode SNESTestJacobian(SNES);
927 PETSC_EXTERN PetscErrorCode SNESTestFunction(SNES);
928 
929 PETSC_EXTERN PetscErrorCode SNESSetDM(SNES, DM);
930 PETSC_EXTERN PetscErrorCode SNESGetDM(SNES, DM *);
931 PETSC_EXTERN PetscErrorCode SNESSetNPC(SNES, SNES);
932 PETSC_EXTERN PetscErrorCode SNESGetNPC(SNES, SNES *);
933 PETSC_EXTERN PetscErrorCode SNESHasNPC(SNES, PetscBool *);
934 PETSC_EXTERN PetscErrorCode SNESApplyNPC(SNES, Vec, Vec, Vec);
935 PETSC_EXTERN PetscErrorCode SNESGetNPCFunction(SNES, Vec, PetscReal *);
936 PETSC_EXTERN PetscErrorCode SNESComputeFunctionDefaultNPC(SNES, Vec, Vec);
937 PETSC_EXTERN PetscErrorCode SNESSetNPCSide(SNES, PCSide);
938 PETSC_EXTERN PetscErrorCode SNESGetNPCSide(SNES, PCSide *);
939 PETSC_EXTERN PetscErrorCode SNESSetLineSearch(SNES, SNESLineSearch);
940 PETSC_EXTERN PetscErrorCode SNESGetLineSearch(SNES, SNESLineSearch *);
941 
942 PETSC_DEPRECATED_FUNCTION(3, 4, 0, "SNESGetLineSearch()", ) static inline PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *ls)
943 {
944   return SNESGetLineSearch(snes, ls);
945 }
946 PETSC_DEPRECATED_FUNCTION(3, 4, 0, "SNESSetLineSearch()", ) static inline PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch ls)
947 {
948   return SNESSetLineSearch(snes, ls);
949 }
950 
951 PETSC_EXTERN PetscErrorCode SNESSetUpMatrices(SNES);
952 PETSC_EXTERN PetscErrorCode DMSNESSetFunction(DM, SNESFunctionFn *, void *);
953 PETSC_EXTERN PetscErrorCode DMSNESGetFunction(DM, SNESFunctionFn **, void **);
954 PETSC_EXTERN PetscErrorCode DMSNESSetFunctionContextDestroy(DM, PetscCtxDestroyFn *);
955 PETSC_EXTERN PetscErrorCode DMSNESSetMFFunction(DM, SNESFunctionFn *, void *);
956 PETSC_EXTERN PetscErrorCode DMSNESSetNGS(DM, SNESNGSFn *, void *);
957 PETSC_EXTERN PetscErrorCode DMSNESGetNGS(DM, SNESNGSFn **, void **);
958 PETSC_EXTERN PetscErrorCode DMSNESSetJacobian(DM, SNESJacobianFn *, void *);
959 PETSC_EXTERN PetscErrorCode DMSNESGetJacobian(DM, SNESJacobianFn **, void **);
960 PETSC_EXTERN PetscErrorCode DMSNESSetJacobianContextDestroy(DM, PetscCtxDestroyFn *);
961 PETSC_EXTERN PetscErrorCode DMSNESSetPicard(DM, SNESFunctionFn *, SNESJacobianFn *, void *);
962 PETSC_EXTERN PetscErrorCode DMSNESGetPicard(DM, SNESFunctionFn **, SNESJacobianFn **, void **);
963 PETSC_EXTERN PetscErrorCode DMSNESSetObjective(DM, SNESObjectiveFn *, void *);
964 PETSC_EXTERN PetscErrorCode DMSNESGetObjective(DM, SNESObjectiveFn **, void **);
965 PETSC_EXTERN PetscErrorCode DMCopyDMSNES(DM, DM);
966 
967 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESFunctionFn)(DMDALocalInfo *, void *, void *, void *);
968 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESJacobianFn)(DMDALocalInfo *, void *, Mat, Mat, void *);
969 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESObjectiveFn)(DMDALocalInfo *, void *, PetscReal *, void *);
970 
971 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESFunctionVecFn)(DMDALocalInfo *, Vec, Vec, void *);
972 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESJacobianVecFn)(DMDALocalInfo *, Vec, Mat, Mat, void *);
973 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(DMDASNESObjectiveVecFn)(DMDALocalInfo *, Vec, PetscReal *, void *);
974 
975 PETSC_EXTERN PetscErrorCode DMDASNESSetFunctionLocal(DM, InsertMode, DMDASNESFunctionFn *, void *);
976 PETSC_EXTERN PetscErrorCode DMDASNESSetJacobianLocal(DM, DMDASNESJacobianFn *, void *);
977 PETSC_EXTERN PetscErrorCode DMDASNESSetObjectiveLocal(DM, DMDASNESObjectiveFn *, void *);
978 PETSC_EXTERN PetscErrorCode DMDASNESSetPicardLocal(DM, InsertMode, DMDASNESFunctionFn *, DMDASNESJacobianFn, void *);
979 
980 PETSC_EXTERN PetscErrorCode DMDASNESSetFunctionLocalVec(DM, InsertMode, DMDASNESFunctionVecFn *, void *);
981 PETSC_EXTERN PetscErrorCode DMDASNESSetJacobianLocalVec(DM, DMDASNESJacobianVecFn *, void *);
982 PETSC_EXTERN PetscErrorCode DMDASNESSetObjectiveLocalVec(DM, DMDASNESObjectiveVecFn *, void *);
983 
984 PETSC_EXTERN PetscErrorCode DMSNESSetBoundaryLocal(DM, PetscErrorCode (*)(DM, Vec, void *), void *);
985 PETSC_EXTERN PetscErrorCode DMSNESSetObjectiveLocal(DM, PetscErrorCode (*)(DM, Vec, PetscReal *, void *), void *);
986 PETSC_EXTERN PetscErrorCode DMSNESSetFunctionLocal(DM, PetscErrorCode (*)(DM, Vec, Vec, void *), void *);
987 PETSC_EXTERN PetscErrorCode DMSNESSetJacobianLocal(DM, PetscErrorCode (*)(DM, Vec, Mat, Mat, void *), void *);
988 PETSC_EXTERN PetscErrorCode DMSNESGetBoundaryLocal(DM, PetscErrorCode (**)(DM, Vec, void *), void **);
989 PETSC_EXTERN PetscErrorCode DMSNESGetObjectiveLocal(DM, PetscErrorCode (**)(DM, Vec, PetscReal *, void *), void **);
990 PETSC_EXTERN PetscErrorCode DMSNESGetFunctionLocal(DM, PetscErrorCode (**)(DM, Vec, Vec, void *), void **);
991 PETSC_EXTERN PetscErrorCode DMSNESGetJacobianLocal(DM, PetscErrorCode (**)(DM, Vec, Mat, Mat, void *), void **);
992 
993 /* Routines for Multiblock solver */
994 PETSC_EXTERN PetscErrorCode SNESMultiblockSetFields(SNES, const char[], PetscInt, const PetscInt *);
995 PETSC_EXTERN PetscErrorCode SNESMultiblockSetIS(SNES, const char[], IS);
996 PETSC_EXTERN PetscErrorCode SNESMultiblockSetBlockSize(SNES, PetscInt);
997 PETSC_EXTERN PetscErrorCode SNESMultiblockSetType(SNES, PCCompositeType);
998 PETSC_EXTERN PetscErrorCode SNESMultiblockGetSubSNES(SNES, PetscInt *, SNES *[]);
999 
1000 /*J
1001    SNESMSType - String with the name of a PETSc `SNESMS` method.
1002 
1003    Level: intermediate
1004 
1005 .seealso: [](ch_snes), `SNESMS`, `SNESMSGetType()`, `SNESMSSetType()`, `SNES`
1006 J*/
1007 typedef const char *SNESMSType;
1008 #define SNESMSM62       "m62"
1009 #define SNESMSEULER     "euler"
1010 #define SNESMSJAMESON83 "jameson83"
1011 #define SNESMSVLTP11    "vltp11"
1012 #define SNESMSVLTP21    "vltp21"
1013 #define SNESMSVLTP31    "vltp31"
1014 #define SNESMSVLTP41    "vltp41"
1015 #define SNESMSVLTP51    "vltp51"
1016 #define SNESMSVLTP61    "vltp61"
1017 
1018 PETSC_EXTERN PetscErrorCode SNESMSRegister(SNESMSType, PetscInt, PetscInt, PetscReal, const PetscReal[], const PetscReal[], const PetscReal[]);
1019 PETSC_EXTERN PetscErrorCode SNESMSRegisterAll(void);
1020 PETSC_EXTERN PetscErrorCode SNESMSGetType(SNES, SNESMSType *);
1021 PETSC_EXTERN PetscErrorCode SNESMSSetType(SNES, SNESMSType);
1022 PETSC_EXTERN PetscErrorCode SNESMSGetDamping(SNES, PetscReal *);
1023 PETSC_EXTERN PetscErrorCode SNESMSSetDamping(SNES, PetscReal);
1024 PETSC_EXTERN PetscErrorCode SNESMSFinalizePackage(void);
1025 PETSC_EXTERN PetscErrorCode SNESMSInitializePackage(void);
1026 PETSC_EXTERN PetscErrorCode SNESMSRegisterDestroy(void);
1027 
1028 /*MC
1029    SNESNGMRESRestartType - the restart approach used by `SNESNGMRES`
1030 
1031   Values:
1032 +   `SNES_NGMRES_RESTART_NONE`       - never restart
1033 .   `SNES_NGMRES_RESTART_DIFFERENCE` - restart based upon difference criteria
1034 -   `SNES_NGMRES_RESTART_PERIODIC`   - restart after a fixed number of iterations
1035 
1036   Options Database Keys:
1037 + -snes_ngmres_restart_type <difference,periodic,none> - set the restart type
1038 - -snes_ngmres_restart <30>                            - sets the number of iterations before restart for periodic
1039 
1040    Level: intermediate
1041 
1042 .seealso: `SNES, `SNESNGMRES`, `SNESNGMRESSetSelectType()`, `SNESNGMRESGetSelectType()`, `SNESNGMRESSetRestartType()`,
1043           `SNESNGMRESGetRestartType()`, `SNESNGMRESSelectType`
1044 M*/
1045 typedef enum {
1046   SNES_NGMRES_RESTART_NONE       = 0,
1047   SNES_NGMRES_RESTART_PERIODIC   = 1,
1048   SNES_NGMRES_RESTART_DIFFERENCE = 2
1049 } SNESNGMRESRestartType;
1050 PETSC_EXTERN const char *const SNESNGMRESRestartTypes[];
1051 
1052 /*MC
1053    SNESNGMRESSelectType - the approach used by `SNESNGMRES` to determine how the candidate solution and
1054   combined solution are used to create the next iterate.
1055 
1056    Values:
1057 +   `SNES_NGMRES_SELECT_NONE`       - choose the combined solution all the time
1058 .   `SNES_NGMRES_SELECT_DIFFERENCE` - choose based upon the selection criteria
1059 -   `SNES_NGMRES_SELECT_LINESEARCH` - choose based upon line search combination
1060 
1061   Options Database Key:
1062 . -snes_ngmres_select_type<difference,none,linesearch> - select type
1063 
1064    Level: intermediate
1065 
1066 .seealso: `SNES, `SNESNGMRES`, `SNESNGMRESSetSelectType()`, `SNESNGMRESGetSelectType()`, `SNESNGMRESSetRestartType()`,
1067           `SNESNGMRESGetRestartType()`, `SNESNGMRESRestartType`
1068 M*/
1069 typedef enum {
1070   SNES_NGMRES_SELECT_NONE       = 0,
1071   SNES_NGMRES_SELECT_DIFFERENCE = 1,
1072   SNES_NGMRES_SELECT_LINESEARCH = 2
1073 } SNESNGMRESSelectType;
1074 PETSC_EXTERN const char *const SNESNGMRESSelectTypes[];
1075 
1076 PETSC_EXTERN PetscErrorCode SNESNGMRESSetRestartType(SNES, SNESNGMRESRestartType);
1077 PETSC_EXTERN PetscErrorCode SNESNGMRESSetSelectType(SNES, SNESNGMRESSelectType);
1078 PETSC_EXTERN PetscErrorCode SNESNGMRESSetRestartFmRise(SNES, PetscBool);
1079 PETSC_EXTERN PetscErrorCode SNESNGMRESGetRestartFmRise(SNES, PetscBool *);
1080 
1081 /*MC
1082    SNESNCGType - the conjugate update approach for `SNESNCG`
1083 
1084    Values:
1085 +   `SNES_NCG_FR`  - Fletcher-Reeves update
1086 .   `SNES_NCG_PRP` - Polak-Ribiere-Polyak update, the default and the only one that tolerates generalized search directions
1087 .   `SNES_NCG_HS`  - Hestenes-Steifel update
1088 .   `SNES_NCG_DY`  - Dai-Yuan update
1089 -   `SNES_NCG_CD`  - Conjugate Descent update
1090 
1091   Options Database Key:
1092 . -snes_ncg_type<fr,prp,hs,dy,cd> - select type
1093 
1094    Level: intermediate
1095 
1096 .seealso: `SNES, `SNESNCG`, `SNESNCGSetType()`
1097 M*/
1098 typedef enum {
1099   SNES_NCG_FR  = 0,
1100   SNES_NCG_PRP = 1,
1101   SNES_NCG_HS  = 2,
1102   SNES_NCG_DY  = 3,
1103   SNES_NCG_CD  = 4
1104 } SNESNCGType;
1105 PETSC_EXTERN const char *const SNESNCGTypes[];
1106 
1107 PETSC_EXTERN PetscErrorCode SNESNCGSetType(SNES, SNESNCGType);
1108 
1109 /*MC
1110    SNESQNScaleType - the scaling type used by `SNESQN`
1111 
1112    Values:
1113 +   `SNES_QN_SCALE_NONE`     - don't scale the problem
1114 .   `SNES_QN_SCALE_SCALAR`   - use Shanno scaling
1115 .   `SNES_QN_SCALE_DIAGONAL` - scale with a diagonalized BFGS formula (see Gilbert and Lemarechal 1989), available
1116 -   `SNES_QN_SCALE_JACOBIAN` - scale by solving a linear system coming from the Jacobian you provided with `SNESSetJacobian()`
1117                                computed at the first iteration of `SNESQN` and at ever restart.
1118 
1119     Options Database Key:
1120 . -snes_qn_scale_type <diagonal,none,scalar,jacobian> - Scaling type
1121 
1122    Level: intermediate
1123 
1124 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNType`, `SNESQNSetType()`, `SNESQNSetRestartType()`, `SNESQNRestartType`
1125 M*/
1126 typedef enum {
1127   SNES_QN_SCALE_DEFAULT  = 0,
1128   SNES_QN_SCALE_NONE     = 1,
1129   SNES_QN_SCALE_SCALAR   = 2,
1130   SNES_QN_SCALE_DIAGONAL = 3,
1131   SNES_QN_SCALE_JACOBIAN = 4
1132 } SNESQNScaleType;
1133 PETSC_EXTERN const char *const SNESQNScaleTypes[];
1134 
1135 /*MC
1136    SNESQNRestartType - the restart approached used by `SNESQN`
1137 
1138    Values:
1139 +   `SNES_QN_RESTART_NONE`     - never restart
1140 .   `SNES_QN_RESTART_POWELL`   - restart based upon descent criteria
1141 -   `SNES_QN_RESTART_PERIODIC` - restart after a fixed number of iterations
1142 
1143   Options Database Keys:
1144 + -snes_qn_restart_type <powell,periodic,none> - set the restart type
1145 - -snes_qn_m <m>                               - sets the number of stored updates and the restart period for periodic
1146 
1147    Level: intermediate
1148 
1149 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNType`, `SNESQNSetType()`, `SNESQNSetRestartType()`, `SNESQNScaleType`
1150 M*/
1151 typedef enum {
1152   SNES_QN_RESTART_DEFAULT  = 0,
1153   SNES_QN_RESTART_NONE     = 1,
1154   SNES_QN_RESTART_POWELL   = 2,
1155   SNES_QN_RESTART_PERIODIC = 3
1156 } SNESQNRestartType;
1157 PETSC_EXTERN const char *const SNESQNRestartTypes[];
1158 
1159 /*MC
1160    SNESQNType - the type used by `SNESQN`
1161 
1162   Values:
1163 +   `SNES_QN_LBFGS`      - LBFGS variant
1164 .   `SNES_QN_BROYDEN`    - Broyden variant
1165 -   `SNES_QN_BADBROYDEN` - Bad Broyden variant
1166 
1167   Options Database Key:
1168 . -snes_qn_type <lbfgs,broyden,badbroyden> - quasi-Newton type
1169 
1170    Level: intermediate
1171 
1172 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNSetType()`, `SNESQNScaleType`, `SNESQNRestartType`, `SNESQNSetRestartType()`
1173 M*/
1174 typedef enum {
1175   SNES_QN_LBFGS      = 0,
1176   SNES_QN_BROYDEN    = 1,
1177   SNES_QN_BADBROYDEN = 2
1178 } SNESQNType;
1179 PETSC_EXTERN const char *const SNESQNTypes[];
1180 
1181 PETSC_EXTERN PetscErrorCode SNESQNSetType(SNES, SNESQNType);
1182 PETSC_EXTERN PetscErrorCode SNESQNSetScaleType(SNES, SNESQNScaleType);
1183 PETSC_EXTERN PetscErrorCode SNESQNSetRestartType(SNES, SNESQNRestartType);
1184 
1185 PETSC_EXTERN PetscErrorCode SNESNASMGetType(SNES, PCASMType *);
1186 PETSC_EXTERN PetscErrorCode SNESNASMSetType(SNES, PCASMType);
1187 PETSC_EXTERN PetscErrorCode SNESNASMGetSubdomains(SNES, PetscInt *, SNES **, VecScatter **, VecScatter **, VecScatter **);
1188 PETSC_EXTERN PetscErrorCode SNESNASMSetSubdomains(SNES, PetscInt, SNES *, VecScatter *, VecScatter *, VecScatter *);
1189 PETSC_EXTERN PetscErrorCode SNESNASMSetDamping(SNES, PetscReal);
1190 PETSC_EXTERN PetscErrorCode SNESNASMGetDamping(SNES, PetscReal *);
1191 PETSC_EXTERN PetscErrorCode SNESNASMGetSubdomainVecs(SNES, PetscInt *, Vec **, Vec **, Vec **, Vec **);
1192 PETSC_EXTERN PetscErrorCode SNESNASMSetComputeFinalJacobian(SNES, PetscBool);
1193 PETSC_EXTERN PetscErrorCode SNESNASMGetSNES(SNES, PetscInt, SNES *);
1194 PETSC_EXTERN PetscErrorCode SNESNASMGetNumber(SNES, PetscInt *);
1195 PETSC_EXTERN PetscErrorCode SNESNASMSetWeight(SNES, Vec);
1196 
1197 /*E
1198   SNESCompositeType - Determines how two or more preconditioners are composed with the `SNESType` of `SNESCOMPOSITE`
1199 
1200   Values:
1201 + `SNES_COMPOSITE_ADDITIVE`        - results from application of all preconditioners are added together
1202 . `SNES_COMPOSITE_MULTIPLICATIVE`  - preconditioners are applied sequentially to the residual freshly
1203                                      computed after the previous preconditioner application
1204 - `SNES_COMPOSITE_ADDITIVEOPTIMAL` - uses a linear combination of the solutions obtained with each preconditioner that approximately minimize the function
1205                                      value at the new iteration.
1206 
1207    Level: beginner
1208 
1209 .seealso: [](sec_pc), `PCCOMPOSITE`, `PCFIELDSPLIT`, `PC`, `PCCompositeSetType()`, `PCCompositeType`
1210 E*/
1211 typedef enum {
1212   SNES_COMPOSITE_ADDITIVE,
1213   SNES_COMPOSITE_MULTIPLICATIVE,
1214   SNES_COMPOSITE_ADDITIVEOPTIMAL
1215 } SNESCompositeType;
1216 PETSC_EXTERN const char *const SNESCompositeTypes[];
1217 
1218 PETSC_EXTERN PetscErrorCode SNESCompositeSetType(SNES, SNESCompositeType);
1219 PETSC_EXTERN PetscErrorCode SNESCompositeAddSNES(SNES, SNESType);
1220 PETSC_EXTERN PetscErrorCode SNESCompositeGetSNES(SNES, PetscInt, SNES *);
1221 PETSC_EXTERN PetscErrorCode SNESCompositeGetNumber(SNES, PetscInt *);
1222 PETSC_EXTERN PetscErrorCode SNESCompositeSetDamping(SNES, PetscInt, PetscReal);
1223 
1224 PETSC_EXTERN PetscErrorCode SNESPatchSetDiscretisationInfo(SNES, PetscInt, DM *, PetscInt *, PetscInt *, const PetscInt **, const PetscInt *, PetscInt, const PetscInt *, PetscInt, const PetscInt *);
1225 PETSC_EXTERN PetscErrorCode SNESPatchSetComputeOperator(SNES, PetscErrorCode (*func)(PC, PetscInt, Vec, Mat, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *);
1226 PETSC_EXTERN PetscErrorCode SNESPatchSetComputeFunction(SNES, PetscErrorCode (*func)(PC, PetscInt, Vec, Vec, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *);
1227 PETSC_EXTERN PetscErrorCode SNESPatchSetConstructType(SNES, PCPatchConstructType, PetscErrorCode (*func)(PC, PetscInt *, IS **, IS *, void *), void *);
1228 PETSC_EXTERN PetscErrorCode SNESPatchSetCellNumbering(SNES, PetscSection);
1229 
1230 /*E
1231     SNESFASType - Determines the type of nonlinear multigrid method that is run.
1232 
1233    Values:
1234 +  `SNES_FAS_MULTIPLICATIVE` (default) - traditional V or W cycle as determined by `SNESFASSetCycles()`
1235 .  `SNES_FAS_ADDITIVE`                 - additive FAS cycle
1236 .  `SNES_FAS_FULL`                     - full FAS cycle
1237 -  `SNES_FAS_KASKADE`                  - Kaskade FAS cycle
1238 
1239    Level: beginner
1240 
1241 .seealso: [](ch_snes), `SNESFAS`, `PCMGSetType()`, `PCMGType`
1242 E*/
1243 typedef enum {
1244   SNES_FAS_MULTIPLICATIVE,
1245   SNES_FAS_ADDITIVE,
1246   SNES_FAS_FULL,
1247   SNES_FAS_KASKADE
1248 } SNESFASType;
1249 PETSC_EXTERN const char *const SNESFASTypes[];
1250 
1251 /* called on the finest level FAS instance*/
1252 PETSC_EXTERN PetscErrorCode SNESFASSetType(SNES, SNESFASType);
1253 PETSC_EXTERN PetscErrorCode SNESFASGetType(SNES, SNESFASType *);
1254 PETSC_EXTERN PetscErrorCode SNESFASSetLevels(SNES, PetscInt, MPI_Comm *);
1255 PETSC_EXTERN PetscErrorCode SNESFASGetLevels(SNES, PetscInt *);
1256 PETSC_EXTERN PetscErrorCode SNESFASGetCycleSNES(SNES, PetscInt, SNES *);
1257 PETSC_EXTERN PetscErrorCode SNESFASSetNumberSmoothUp(SNES, PetscInt);
1258 PETSC_EXTERN PetscErrorCode SNESFASSetNumberSmoothDown(SNES, PetscInt);
1259 PETSC_EXTERN PetscErrorCode SNESFASSetCycles(SNES, PetscInt);
1260 PETSC_EXTERN PetscErrorCode SNESFASSetMonitor(SNES, PetscViewerAndFormat *, PetscBool);
1261 PETSC_EXTERN PetscErrorCode SNESFASSetLog(SNES, PetscBool);
1262 
1263 PETSC_EXTERN PetscErrorCode SNESFASSetGalerkin(SNES, PetscBool);
1264 PETSC_EXTERN PetscErrorCode SNESFASGetGalerkin(SNES, PetscBool *);
1265 PETSC_EXTERN PetscErrorCode SNESFASGalerkinFunctionDefault(SNES, Vec, Vec, void *);
1266 
1267 /* called on any level -- "Cycle" FAS instance */
1268 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmoother(SNES, SNES *);
1269 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmootherUp(SNES, SNES *);
1270 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmootherDown(SNES, SNES *);
1271 PETSC_EXTERN PetscErrorCode SNESFASCycleGetCorrection(SNES, SNES *);
1272 PETSC_EXTERN PetscErrorCode SNESFASCycleGetInterpolation(SNES, Mat *);
1273 PETSC_EXTERN PetscErrorCode SNESFASCycleGetRestriction(SNES, Mat *);
1274 PETSC_EXTERN PetscErrorCode SNESFASCycleGetInjection(SNES, Mat *);
1275 PETSC_EXTERN PetscErrorCode SNESFASCycleGetRScale(SNES, Vec *);
1276 PETSC_EXTERN PetscErrorCode SNESFASCycleSetCycles(SNES, PetscInt);
1277 PETSC_EXTERN PetscErrorCode SNESFASCycleIsFine(SNES, PetscBool *);
1278 
1279 /* called on the (outer) finest level FAS to set/get parameters on any level instance */
1280 PETSC_EXTERN PetscErrorCode SNESFASSetInterpolation(SNES, PetscInt, Mat);
1281 PETSC_EXTERN PetscErrorCode SNESFASGetInterpolation(SNES, PetscInt, Mat *);
1282 PETSC_EXTERN PetscErrorCode SNESFASSetRestriction(SNES, PetscInt, Mat);
1283 PETSC_EXTERN PetscErrorCode SNESFASGetRestriction(SNES, PetscInt, Mat *);
1284 PETSC_EXTERN PetscErrorCode SNESFASSetInjection(SNES, PetscInt, Mat);
1285 PETSC_EXTERN PetscErrorCode SNESFASGetInjection(SNES, PetscInt, Mat *);
1286 PETSC_EXTERN PetscErrorCode SNESFASSetRScale(SNES, PetscInt, Vec);
1287 PETSC_EXTERN PetscErrorCode SNESFASGetRScale(SNES, PetscInt, Vec *);
1288 PETSC_EXTERN PetscErrorCode SNESFASSetContinuation(SNES, PetscBool);
1289 
1290 PETSC_EXTERN PetscErrorCode SNESFASGetSmoother(SNES, PetscInt, SNES *);
1291 PETSC_EXTERN PetscErrorCode SNESFASGetSmootherUp(SNES, PetscInt, SNES *);
1292 PETSC_EXTERN PetscErrorCode SNESFASGetSmootherDown(SNES, PetscInt, SNES *);
1293 PETSC_EXTERN PetscErrorCode SNESFASGetCoarseSolve(SNES, SNES *);
1294 
1295 /* parameters for full FAS */
1296 PETSC_EXTERN PetscErrorCode SNESFASFullSetDownSweep(SNES, PetscBool);
1297 PETSC_EXTERN PetscErrorCode SNESFASCreateCoarseVec(SNES, Vec *);
1298 PETSC_EXTERN PetscErrorCode SNESFASRestrict(SNES, Vec, Vec);
1299 PETSC_EXTERN PetscErrorCode SNESFASFullSetTotal(SNES, PetscBool);
1300 PETSC_EXTERN PetscErrorCode SNESFASFullGetTotal(SNES, PetscBool *);
1301 
1302 PETSC_EXTERN PetscErrorCode DMSNESCheckDiscretization(SNES, DM, PetscReal, Vec, PetscReal, PetscReal[]);
1303 PETSC_EXTERN PetscErrorCode DMSNESCheckResidual(SNES, DM, Vec, PetscReal, PetscReal *);
1304 PETSC_EXTERN PetscErrorCode DMSNESCheckJacobian(SNES, DM, Vec, PetscReal, PetscBool *, PetscReal *);
1305 PETSC_EXTERN PetscErrorCode DMSNESCheckFromOptions(SNES, Vec);
1306 PETSC_EXTERN PetscErrorCode DMSNESComputeJacobianAction(DM, Vec, Vec, Vec, void *);
1307 PETSC_EXTERN PetscErrorCode DMSNESCreateJacobianMF(DM, Vec, void *, Mat *);
1308 
1309 PETSC_EXTERN PetscErrorCode SNESNewtonALSetFunction(SNES, SNESFunctionFn *, void *ctx);
1310 PETSC_EXTERN PetscErrorCode SNESNewtonALGetFunction(SNES, SNESFunctionFn **, void **ctx);
1311 PETSC_EXTERN PetscErrorCode SNESNewtonALComputeFunction(SNES, Vec, Vec);
1312 PETSC_EXTERN PetscErrorCode SNESNewtonALGetLoadParameter(SNES, PetscReal *);
1313 
1314 /*MC
1315    SNESNewtonALCorrectionType - the approach used by `SNESNEWTONAL` to determine
1316    the correction to the current increment. While the exact correction satisfies
1317    the constraint surface at every iteration, it also requires solving a quadratic
1318    equation which may not have real roots. Conversely, the normal correction is more
1319    efficient and always yields a real correction and is the default.
1320 
1321    Values:
1322 +   `SNES_NEWTONAL_CORRECTION_EXACT` - choose the correction which exactly satisfies the constraint
1323 -   `SNES_NEWTONAL_CORRECTION_NORMAL` - choose the correction in the updated normal hyper-surface to the constraint surface
1324 
1325    Options Database Key:
1326 . -snes_newtonal_correction_type <exact> - select type from <exact,normal>
1327 
1328    Level: intermediate
1329 
1330 .seealso: `SNES`, `SNESNEWTONAL`, `SNESNewtonALSetCorrectionType()`
1331 M*/
1332 typedef enum {
1333   SNES_NEWTONAL_CORRECTION_EXACT  = 0,
1334   SNES_NEWTONAL_CORRECTION_NORMAL = 1,
1335 } SNESNewtonALCorrectionType;
1336 PETSC_EXTERN const char *const SNESNewtonALCorrectionTypes[];
1337 
1338 PETSC_EXTERN PetscErrorCode SNESNewtonALSetCorrectionType(SNES, SNESNewtonALCorrectionType);
1339