xref: /petsc/include/petscsnes.h (revision ccfb0f9f40a0131988d7995ed9679700dae2a75a)
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 or an objective function
715 .  `SNESLINESEARCHSECANT`    - Secant line search over the L2 norm of the function or an objective 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 -  `SNESLINESEARCHBISECTION` - bisection line search for a root in the directional derivative
719 -  `SNESLINESEARCHSHELL`     - User provided `SNESLineSearch` implementation
720 
721    Level: beginner
722 
723    Note:
724    Use `SNESLineSearchSetType()` or the options database key `-snes_linesearch_type` to set
725    the specific line search algorithm to use with a given `SNES` object. Not all `SNESType` can utilize a line search.
726 
727 .seealso: [](ch_snes), `SNESLineSearch`, `SNESLineSearchSetType()`, `SNES`
728 J*/
729 typedef const char *SNESLineSearchType;
730 #define SNESLINESEARCHBT        "bt"
731 #define SNESLINESEARCHNLEQERR   "nleqerr"
732 #define SNESLINESEARCHBASIC     "basic"
733 #define SNESLINESEARCHNONE      "none"
734 #define SNESLINESEARCHSECANT    "secant"
735 #define SNESLINESEARCHL2        PETSC_DEPRECATED_MACRO(3, 24, 0, "SNESLINESEARCHSECANT", ) "secant"
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 PETSC_DEPRECATED_TYPEDEF(3, 21, 0, "SNESLineSearchVIProjectFn*", );
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 PETSC_DEPRECATED_TYPEDEF(3, 21, 0, "SNESLineSearchVINormFnn*", );
785 
786 /*S
787   SNESLineSearchVIDirDerivFn - A prototype of a `SNES` function that computes the directional derivative considering the VI bounds, passed to `SNESLineSearchSetVIFunctions()`
788 
789   Calling Sequence:
790 + snes  - `SNES` context
791 . f     - the function vector to compute the directional derivative with
792 . u     - the current solution, entries that are on the VI bounds are ignored
793 . y     - the direction to compute the directional derivative
794 - fty   - the resulting directional derivative
795 
796   Level: advanced
797 
798 .seealso: [](ch_snes), `SNES`, `SNESLineSearch`, `SNESLineSearchVIProjectFn`, `SNESLineSearchVIProjectFn`, `SNESLineSearchSetVIFunctions()`, `SNESLineSearchGetVIFunctions()`
799 S*/
800 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode SNESLineSearchVIDirDerivFn(SNES snes, Vec f, Vec u, Vec y, PetscScalar *fty);
801 
802 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode              SNESLineSearchApplyFn(SNESLineSearch);
803 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchApplyFn      *SNESLineSearchApplyFunc PETSC_DEPRECATED_TYPEDEF(3, 21, 0, "SNESLineSearchApplyFn*", );
804 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode              SNESLineSearchShellApplyFn(SNESLineSearch, void *);
805 PETSC_EXTERN_TYPEDEF typedef SNESLineSearchShellApplyFn *SNESLineSearchUserFunc PETSC_DEPRECATED_TYPEDEF(3, 21, 0, "SNESLineSearchApplyFn*", );
806 
807 PETSC_EXTERN PetscErrorCode SNESLineSearchCreate(MPI_Comm, SNESLineSearch *);
808 PETSC_EXTERN PetscErrorCode SNESLineSearchReset(SNESLineSearch);
809 PETSC_EXTERN PetscErrorCode SNESLineSearchView(SNESLineSearch, PetscViewer);
810 PETSC_EXTERN PetscErrorCode SNESLineSearchDestroy(SNESLineSearch *);
811 PETSC_EXTERN PetscErrorCode SNESLineSearchGetType(SNESLineSearch, SNESLineSearchType *);
812 PETSC_EXTERN PetscErrorCode SNESLineSearchSetType(SNESLineSearch, SNESLineSearchType);
813 PETSC_EXTERN PetscErrorCode SNESLineSearchSetFromOptions(SNESLineSearch);
814 PETSC_EXTERN PetscErrorCode SNESLineSearchSetFunction(SNESLineSearch, PetscErrorCode (*)(SNES, Vec, Vec));
815 PETSC_EXTERN PetscErrorCode SNESLineSearchSetUp(SNESLineSearch);
816 PETSC_EXTERN PetscErrorCode SNESLineSearchApply(SNESLineSearch, Vec, Vec, PetscReal *, Vec);
817 PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheck(SNESLineSearch, Vec, Vec, PetscBool *);
818 PETSC_EXTERN PetscErrorCode SNESLineSearchPostCheck(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *);
819 PETSC_EXTERN PetscErrorCode SNESLineSearchSetWorkVecs(SNESLineSearch, PetscInt);
820 
821 /* set the functions for precheck and postcheck */
822 
823 PETSC_EXTERN PetscErrorCode SNESLineSearchSetPreCheck(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, Vec, Vec, PetscBool *, void *), void *ctx);
824 PETSC_EXTERN PetscErrorCode SNESLineSearchSetPostCheck(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void *ctx);
825 
826 PETSC_EXTERN PetscErrorCode SNESLineSearchGetPreCheck(SNESLineSearch, PetscErrorCode (**)(SNESLineSearch, Vec, Vec, PetscBool *, void *), void **ctx);
827 PETSC_EXTERN PetscErrorCode SNESLineSearchGetPostCheck(SNESLineSearch, PetscErrorCode (**)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *), void **ctx);
828 
829 /* set the functions for VI-specific line search operations */
830 
831 PETSC_EXTERN PetscErrorCode SNESLineSearchSetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn *, SNESLineSearchVINormFn *, SNESLineSearchVIDirDerivFn *);
832 PETSC_EXTERN PetscErrorCode SNESLineSearchGetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn **, SNESLineSearchVINormFn **, SNESLineSearchVIDirDerivFn **);
833 
834 /* pointers to the associated SNES in order to be able to get the function evaluation out */
835 PETSC_EXTERN PetscErrorCode SNESLineSearchSetSNES(SNESLineSearch, SNES);
836 PETSC_EXTERN PetscErrorCode SNESLineSearchGetSNES(SNESLineSearch, SNES *);
837 
838 /* set and get the parameters and vectors */
839 PETSC_EXTERN PetscErrorCode SNESLineSearchGetTolerances(SNESLineSearch, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscReal *, PetscInt *);
840 PETSC_EXTERN PetscErrorCode SNESLineSearchSetTolerances(SNESLineSearch, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal, PetscInt);
841 
842 PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch, Vec, Vec, PetscBool *, void *);
843 
844 PETSC_EXTERN PetscErrorCode SNESLineSearchGetLambda(SNESLineSearch, PetscReal *);
845 PETSC_EXTERN PetscErrorCode SNESLineSearchSetLambda(SNESLineSearch, PetscReal);
846 
847 PETSC_EXTERN PetscErrorCode SNESLineSearchGetDamping(SNESLineSearch, PetscReal *);
848 PETSC_EXTERN PetscErrorCode SNESLineSearchSetDamping(SNESLineSearch, PetscReal);
849 
850 PETSC_EXTERN PetscErrorCode SNESLineSearchGetOrder(SNESLineSearch, PetscInt *);
851 PETSC_EXTERN PetscErrorCode SNESLineSearchSetOrder(SNESLineSearch, PetscInt);
852 
853 /*E
854     SNESLineSearchReason - indication if the line search has succeeded or failed and why
855 
856   Values:
857 +  `SNES_LINESEARCH_SUCCEEDED`       - the line search succeeded
858 .  `SNES_LINESEARCH_FAILED_NANORINF` - a not a number of infinity appeared in the computions
859 .  `SNES_LINESEARCH_FAILED_DOMAIN`   - the function was evaluated outside of its domain, see `SNESSetFunctionDomainError()` and `SNESSetJacobianDomainError()`
860 .  `SNES_LINESEARCH_FAILED_REDUCT`   - the linear search failed to get the requested decrease in its norm or objective
861 .  `SNES_LINESEARCH_FAILED_USER`     - used by `SNESLINESEARCHNLEQERR` to indicate the user changed the search direction inappropriately
862 -  `SNES_LINESEARCH_FAILED_FUNCTION` - indicates the maximum number of function evaluations allowed has been surpassed, `SNESConvergedReason` is also
863                                        set to `SNES_DIVERGED_FUNCTION_COUNT`
864 
865    Level: intermediate
866 
867    Developer Note:
868    Some of these reasons overlap with values of `SNESConvergedReason`
869 
870 .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `KSPConvergedReason`, `SNESSetConvergenceTest()`,
871           `SNESSetFunctionDomainError()` and `SNESSetJacobianDomainError()`
872 E*/
873 typedef enum {
874   SNES_LINESEARCH_SUCCEEDED,
875   SNES_LINESEARCH_FAILED_NANORINF,
876   SNES_LINESEARCH_FAILED_DOMAIN,
877   SNES_LINESEARCH_FAILED_REDUCT, /* INSUFFICIENT REDUCTION */
878   SNES_LINESEARCH_FAILED_USER,
879   SNES_LINESEARCH_FAILED_FUNCTION
880 } SNESLineSearchReason;
881 
882 PETSC_EXTERN PetscErrorCode SNESLineSearchGetReason(SNESLineSearch, SNESLineSearchReason *);
883 PETSC_EXTERN PetscErrorCode SNESLineSearchSetReason(SNESLineSearch, SNESLineSearchReason);
884 
885 PETSC_EXTERN PetscErrorCode SNESLineSearchGetVecs(SNESLineSearch, Vec *, Vec *, Vec *, Vec *, Vec *);
886 PETSC_EXTERN PetscErrorCode SNESLineSearchSetVecs(SNESLineSearch, Vec, Vec, Vec, Vec, Vec);
887 
888 PETSC_EXTERN PetscErrorCode SNESLineSearchGetNorms(SNESLineSearch, PetscReal *, PetscReal *, PetscReal *);
889 PETSC_EXTERN PetscErrorCode SNESLineSearchSetNorms(SNESLineSearch, PetscReal, PetscReal, PetscReal);
890 PETSC_EXTERN PetscErrorCode SNESLineSearchComputeNorms(SNESLineSearch);
891 PETSC_EXTERN PetscErrorCode SNESLineSearchSetComputeNorms(SNESLineSearch, PetscBool);
892 
893 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitor(SNESLineSearch);
894 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSet(SNESLineSearch, PetscErrorCode (*)(SNESLineSearch, void *), void *, PetscCtxDestroyFn *);
895 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSetFromOptions(SNESLineSearch, const char[], const char[], const char[], PetscErrorCode (*)(SNESLineSearch, PetscViewerAndFormat *), PetscErrorCode (*)(SNESLineSearch, PetscViewerAndFormat *));
896 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorCancel(SNESLineSearch);
897 PETSC_EXTERN PetscErrorCode SNESLineSearchSetDefaultMonitor(SNESLineSearch, PetscViewer);
898 PETSC_EXTERN PetscErrorCode SNESLineSearchGetDefaultMonitor(SNESLineSearch, PetscViewer *);
899 PETSC_EXTERN PetscErrorCode SNESLineSearchMonitorSolutionUpdate(SNESLineSearch, PetscViewerAndFormat *);
900 
901 PETSC_EXTERN PetscErrorCode SNESLineSearchAppendOptionsPrefix(SNESLineSearch, const char[]);
902 PETSC_EXTERN PetscErrorCode SNESLineSearchGetOptionsPrefix(SNESLineSearch, const char *[]);
903 
904 /* Shell interface functions */
905 PETSC_EXTERN PetscErrorCode SNESLineSearchShellSetApply(SNESLineSearch, SNESLineSearchShellApplyFn *, void *);
906 PETSC_EXTERN PetscErrorCode SNESLineSearchShellGetApply(SNESLineSearch, SNESLineSearchShellApplyFn **, void **);
907 
908 PETSC_DEPRECATED_FUNCTION(3, 21, 0, "SNESLinesearchShellSetApply()", ) static inline PetscErrorCode SNESLineSearchShellSetUserFunc(SNESLineSearch ls, SNESLineSearchShellApplyFn *f, void *ctx)
909 {
910   return SNESLineSearchShellSetApply(ls, f, ctx);
911 }
912 
913 PETSC_DEPRECATED_FUNCTION(3, 21, 0, "SNESLinesearchShellGetApply()", ) static inline PetscErrorCode SNESLineSearchShellGetUserFunc(SNESLineSearch ls, SNESLineSearchShellApplyFn **f, void **ctx)
914 {
915   return SNESLineSearchShellGetApply(ls, f, ctx);
916 }
917 
918 /* BT interface functions */
919 PETSC_EXTERN PetscErrorCode SNESLineSearchBTSetAlpha(SNESLineSearch, PetscReal);
920 PETSC_EXTERN PetscErrorCode SNESLineSearchBTGetAlpha(SNESLineSearch, PetscReal *);
921 
922 /*register line search types */
923 PETSC_EXTERN PetscErrorCode SNESLineSearchRegister(const char[], PetscErrorCode (*)(SNESLineSearch));
924 
925 /* Routines for VI solver */
926 PETSC_EXTERN PetscErrorCode SNESVISetVariableBounds(SNES, Vec, Vec);
927 PETSC_EXTERN PetscErrorCode SNESVIGetVariableBounds(SNES, Vec *, Vec *);
928 PETSC_EXTERN PetscErrorCode SNESVISetComputeVariableBounds(SNES, PetscErrorCode (*)(SNES, Vec, Vec));
929 PETSC_EXTERN PetscErrorCode SNESVIGetInactiveSet(SNES, IS *);
930 PETSC_EXTERN PetscErrorCode SNESVIGetActiveSetIS(SNES, Vec, Vec, IS *);
931 PETSC_EXTERN PetscErrorCode SNESVIComputeInactiveSetFnorm(SNES, Vec, Vec, PetscReal *);
932 PETSC_EXTERN PetscErrorCode SNESVIComputeInactiveSetFtY(SNES, Vec, Vec, Vec, PetscScalar *);
933 PETSC_EXTERN PetscErrorCode SNESVISetRedundancyCheck(SNES, PetscErrorCode (*)(SNES, IS, IS *, void *), void *);
934 PETSC_EXTERN PetscErrorCode SNESVIComputeMeritFunction(Vec, PetscReal *, PetscReal *);
935 PETSC_EXTERN PetscErrorCode SNESVIComputeFunction(SNES, Vec, Vec, void *);
936 PETSC_EXTERN PetscErrorCode DMSetVI(DM, IS);
937 PETSC_EXTERN PetscErrorCode DMDestroyVI(DM);
938 
939 PETSC_EXTERN PetscErrorCode SNESTestLocalMin(SNES);
940 
941 /* Should this routine be private? */
942 PETSC_EXTERN PetscErrorCode SNESComputeJacobian(SNES, Vec, Mat, Mat);
943 PETSC_EXTERN PetscErrorCode SNESTestJacobian(SNES, PetscReal *, PetscReal *);
944 PETSC_EXTERN PetscErrorCode SNESTestFunction(SNES);
945 
946 PETSC_EXTERN PetscErrorCode SNESSetDM(SNES, DM);
947 PETSC_EXTERN PetscErrorCode SNESGetDM(SNES, DM *);
948 PETSC_EXTERN PetscErrorCode SNESSetNPC(SNES, SNES);
949 PETSC_EXTERN PetscErrorCode SNESGetNPC(SNES, SNES *);
950 PETSC_EXTERN PetscErrorCode SNESHasNPC(SNES, PetscBool *);
951 PETSC_EXTERN PetscErrorCode SNESApplyNPC(SNES, Vec, Vec, Vec);
952 PETSC_EXTERN PetscErrorCode SNESGetNPCFunction(SNES, Vec, PetscReal *);
953 PETSC_EXTERN PetscErrorCode SNESComputeFunctionDefaultNPC(SNES, Vec, Vec);
954 PETSC_EXTERN PetscErrorCode SNESSetNPCSide(SNES, PCSide);
955 PETSC_EXTERN PetscErrorCode SNESGetNPCSide(SNES, PCSide *);
956 PETSC_EXTERN PetscErrorCode SNESSetLineSearch(SNES, SNESLineSearch);
957 PETSC_EXTERN PetscErrorCode SNESGetLineSearch(SNES, SNESLineSearch *);
958 
959 PETSC_DEPRECATED_FUNCTION(3, 4, 0, "SNESGetLineSearch()", ) static inline PetscErrorCode SNESGetSNESLineSearch(SNES snes, SNESLineSearch *ls)
960 {
961   return SNESGetLineSearch(snes, ls);
962 }
963 PETSC_DEPRECATED_FUNCTION(3, 4, 0, "SNESSetLineSearch()", ) static inline PetscErrorCode SNESSetSNESLineSearch(SNES snes, SNESLineSearch ls)
964 {
965   return SNESSetLineSearch(snes, ls);
966 }
967 
968 PETSC_EXTERN PetscErrorCode SNESSetUpMatrices(SNES);
969 PETSC_EXTERN PetscErrorCode DMSNESSetFunction(DM, SNESFunctionFn *, void *);
970 PETSC_EXTERN PetscErrorCode DMSNESGetFunction(DM, SNESFunctionFn **, void **);
971 PETSC_EXTERN PetscErrorCode DMSNESSetFunctionContextDestroy(DM, PetscCtxDestroyFn *);
972 PETSC_EXTERN PetscErrorCode DMSNESSetMFFunction(DM, SNESFunctionFn *, void *);
973 PETSC_EXTERN PetscErrorCode DMSNESSetNGS(DM, SNESNGSFn *, void *);
974 PETSC_EXTERN PetscErrorCode DMSNESGetNGS(DM, SNESNGSFn **, void **);
975 PETSC_EXTERN PetscErrorCode DMSNESSetJacobian(DM, SNESJacobianFn *, void *);
976 PETSC_EXTERN PetscErrorCode DMSNESGetJacobian(DM, SNESJacobianFn **, void **);
977 PETSC_EXTERN PetscErrorCode DMSNESSetJacobianContextDestroy(DM, PetscCtxDestroyFn *);
978 PETSC_EXTERN PetscErrorCode DMSNESSetPicard(DM, SNESFunctionFn *, SNESJacobianFn *, void *);
979 PETSC_EXTERN PetscErrorCode DMSNESGetPicard(DM, SNESFunctionFn **, SNESJacobianFn **, void **);
980 PETSC_EXTERN PetscErrorCode DMSNESSetObjective(DM, SNESObjectiveFn *, void *);
981 PETSC_EXTERN PetscErrorCode DMSNESGetObjective(DM, SNESObjectiveFn **, void **);
982 PETSC_EXTERN PetscErrorCode DMCopyDMSNES(DM, DM);
983 
984 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode DMDASNESFunctionFn(DMDALocalInfo *, void *, void *, void *);
985 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode DMDASNESJacobianFn(DMDALocalInfo *, void *, Mat, Mat, void *);
986 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode DMDASNESObjectiveFn(DMDALocalInfo *, void *, PetscReal *, void *);
987 
988 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode DMDASNESFunctionVecFn(DMDALocalInfo *, Vec, Vec, void *);
989 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode DMDASNESJacobianVecFn(DMDALocalInfo *, Vec, Mat, Mat, void *);
990 PETSC_EXTERN_TYPEDEF typedef PetscErrorCode DMDASNESObjectiveVecFn(DMDALocalInfo *, Vec, PetscReal *, void *);
991 
992 PETSC_EXTERN PetscErrorCode DMDASNESSetFunctionLocal(DM, InsertMode, DMDASNESFunctionFn *, void *);
993 PETSC_EXTERN PetscErrorCode DMDASNESSetJacobianLocal(DM, DMDASNESJacobianFn *, void *);
994 PETSC_EXTERN PetscErrorCode DMDASNESSetObjectiveLocal(DM, DMDASNESObjectiveFn *, void *);
995 PETSC_EXTERN PetscErrorCode DMDASNESSetPicardLocal(DM, InsertMode, DMDASNESFunctionFn *, DMDASNESJacobianFn, void *);
996 
997 PETSC_EXTERN PetscErrorCode DMDASNESSetFunctionLocalVec(DM, InsertMode, DMDASNESFunctionVecFn *, void *);
998 PETSC_EXTERN PetscErrorCode DMDASNESSetJacobianLocalVec(DM, DMDASNESJacobianVecFn *, void *);
999 PETSC_EXTERN PetscErrorCode DMDASNESSetObjectiveLocalVec(DM, DMDASNESObjectiveVecFn *, void *);
1000 
1001 PETSC_EXTERN PetscErrorCode DMSNESSetBoundaryLocal(DM, PetscErrorCode (*)(DM, Vec, void *), void *);
1002 PETSC_EXTERN PetscErrorCode DMSNESSetObjectiveLocal(DM, PetscErrorCode (*)(DM, Vec, PetscReal *, void *), void *);
1003 PETSC_EXTERN PetscErrorCode DMSNESSetFunctionLocal(DM, PetscErrorCode (*)(DM, Vec, Vec, void *), void *);
1004 PETSC_EXTERN PetscErrorCode DMSNESSetJacobianLocal(DM, PetscErrorCode (*)(DM, Vec, Mat, Mat, void *), void *);
1005 PETSC_EXTERN PetscErrorCode DMSNESGetBoundaryLocal(DM, PetscErrorCode (**)(DM, Vec, void *), void **);
1006 PETSC_EXTERN PetscErrorCode DMSNESGetObjectiveLocal(DM, PetscErrorCode (**)(DM, Vec, PetscReal *, void *), void **);
1007 PETSC_EXTERN PetscErrorCode DMSNESGetFunctionLocal(DM, PetscErrorCode (**)(DM, Vec, Vec, void *), void **);
1008 PETSC_EXTERN PetscErrorCode DMSNESGetJacobianLocal(DM, PetscErrorCode (**)(DM, Vec, Mat, Mat, void *), void **);
1009 
1010 /* Routines for Multiblock solver */
1011 PETSC_EXTERN PetscErrorCode SNESMultiblockSetFields(SNES, const char[], PetscInt, const PetscInt *);
1012 PETSC_EXTERN PetscErrorCode SNESMultiblockSetIS(SNES, const char[], IS);
1013 PETSC_EXTERN PetscErrorCode SNESMultiblockSetBlockSize(SNES, PetscInt);
1014 PETSC_EXTERN PetscErrorCode SNESMultiblockSetType(SNES, PCCompositeType);
1015 PETSC_EXTERN PetscErrorCode SNESMultiblockGetSubSNES(SNES, PetscInt *, SNES *[]);
1016 
1017 /*J
1018    SNESMSType - String with the name of a PETSc `SNESMS` method.
1019 
1020    Level: intermediate
1021 
1022 .seealso: [](ch_snes), `SNESMS`, `SNESMSGetType()`, `SNESMSSetType()`, `SNES`
1023 J*/
1024 typedef const char *SNESMSType;
1025 #define SNESMSM62       "m62"
1026 #define SNESMSEULER     "euler"
1027 #define SNESMSJAMESON83 "jameson83"
1028 #define SNESMSVLTP11    "vltp11"
1029 #define SNESMSVLTP21    "vltp21"
1030 #define SNESMSVLTP31    "vltp31"
1031 #define SNESMSVLTP41    "vltp41"
1032 #define SNESMSVLTP51    "vltp51"
1033 #define SNESMSVLTP61    "vltp61"
1034 
1035 PETSC_EXTERN PetscErrorCode SNESMSRegister(SNESMSType, PetscInt, PetscInt, PetscReal, const PetscReal[], const PetscReal[], const PetscReal[]);
1036 PETSC_EXTERN PetscErrorCode SNESMSRegisterAll(void);
1037 PETSC_EXTERN PetscErrorCode SNESMSGetType(SNES, SNESMSType *);
1038 PETSC_EXTERN PetscErrorCode SNESMSSetType(SNES, SNESMSType);
1039 PETSC_EXTERN PetscErrorCode SNESMSGetDamping(SNES, PetscReal *);
1040 PETSC_EXTERN PetscErrorCode SNESMSSetDamping(SNES, PetscReal);
1041 PETSC_EXTERN PetscErrorCode SNESMSFinalizePackage(void);
1042 PETSC_EXTERN PetscErrorCode SNESMSInitializePackage(void);
1043 PETSC_EXTERN PetscErrorCode SNESMSRegisterDestroy(void);
1044 
1045 /*MC
1046    SNESNGMRESRestartType - the restart approach used by `SNESNGMRES`
1047 
1048   Values:
1049 +   `SNES_NGMRES_RESTART_NONE`       - never restart
1050 .   `SNES_NGMRES_RESTART_DIFFERENCE` - restart based upon difference criteria
1051 -   `SNES_NGMRES_RESTART_PERIODIC`   - restart after a fixed number of iterations
1052 
1053   Options Database Keys:
1054 + -snes_ngmres_restart_type <difference,periodic,none> - set the restart type
1055 - -snes_ngmres_restart <30>                            - sets the number of iterations before restart for periodic
1056 
1057    Level: intermediate
1058 
1059 .seealso: `SNES, `SNESNGMRES`, `SNESNGMRESSetSelectType()`, `SNESNGMRESGetSelectType()`, `SNESNGMRESSetRestartType()`,
1060           `SNESNGMRESGetRestartType()`, `SNESNGMRESSelectType`
1061 M*/
1062 typedef enum {
1063   SNES_NGMRES_RESTART_NONE       = 0,
1064   SNES_NGMRES_RESTART_PERIODIC   = 1,
1065   SNES_NGMRES_RESTART_DIFFERENCE = 2
1066 } SNESNGMRESRestartType;
1067 PETSC_EXTERN const char *const SNESNGMRESRestartTypes[];
1068 
1069 /*MC
1070    SNESNGMRESSelectType - the approach used by `SNESNGMRES` to determine how the candidate solution and
1071   combined solution are used to create the next iterate.
1072 
1073    Values:
1074 +   `SNES_NGMRES_SELECT_NONE`       - choose the combined solution all the time
1075 .   `SNES_NGMRES_SELECT_DIFFERENCE` - choose based upon the selection criteria
1076 -   `SNES_NGMRES_SELECT_LINESEARCH` - choose based upon line search combination
1077 
1078   Options Database Key:
1079 . -snes_ngmres_select_type<difference,none,linesearch> - select type
1080 
1081    Level: intermediate
1082 
1083 .seealso: `SNES, `SNESNGMRES`, `SNESNGMRESSetSelectType()`, `SNESNGMRESGetSelectType()`, `SNESNGMRESSetRestartType()`,
1084           `SNESNGMRESGetRestartType()`, `SNESNGMRESRestartType`
1085 M*/
1086 typedef enum {
1087   SNES_NGMRES_SELECT_NONE       = 0,
1088   SNES_NGMRES_SELECT_DIFFERENCE = 1,
1089   SNES_NGMRES_SELECT_LINESEARCH = 2
1090 } SNESNGMRESSelectType;
1091 PETSC_EXTERN const char *const SNESNGMRESSelectTypes[];
1092 
1093 PETSC_EXTERN PetscErrorCode SNESNGMRESSetRestartType(SNES, SNESNGMRESRestartType);
1094 PETSC_EXTERN PetscErrorCode SNESNGMRESSetSelectType(SNES, SNESNGMRESSelectType);
1095 PETSC_EXTERN PetscErrorCode SNESNGMRESSetRestartFmRise(SNES, PetscBool);
1096 PETSC_EXTERN PetscErrorCode SNESNGMRESGetRestartFmRise(SNES, PetscBool *);
1097 
1098 /*MC
1099    SNESNCGType - the conjugate update approach for `SNESNCG`
1100 
1101    Values:
1102 +   `SNES_NCG_FR`  - Fletcher-Reeves update
1103 .   `SNES_NCG_PRP` - Polak-Ribiere-Polyak update, the default and the only one that tolerates generalized search directions
1104 .   `SNES_NCG_HS`  - Hestenes-Steifel update
1105 .   `SNES_NCG_DY`  - Dai-Yuan update
1106 -   `SNES_NCG_CD`  - Conjugate Descent update
1107 
1108   Options Database Key:
1109 . -snes_ncg_type<fr,prp,hs,dy,cd> - select type
1110 
1111    Level: intermediate
1112 
1113 .seealso: `SNES, `SNESNCG`, `SNESNCGSetType()`
1114 M*/
1115 typedef enum {
1116   SNES_NCG_FR  = 0,
1117   SNES_NCG_PRP = 1,
1118   SNES_NCG_HS  = 2,
1119   SNES_NCG_DY  = 3,
1120   SNES_NCG_CD  = 4
1121 } SNESNCGType;
1122 PETSC_EXTERN const char *const SNESNCGTypes[];
1123 
1124 PETSC_EXTERN PetscErrorCode SNESNCGSetType(SNES, SNESNCGType);
1125 
1126 /*MC
1127    SNESQNScaleType - the scaling type used by `SNESQN`
1128 
1129    Values:
1130 +   `SNES_QN_SCALE_NONE`     - don't scale the problem
1131 .   `SNES_QN_SCALE_SCALAR`   - use Shanno scaling
1132 .   `SNES_QN_SCALE_DIAGONAL` - scale with a diagonalized BFGS formula (see Gilbert and Lemarechal 1989), available
1133 -   `SNES_QN_SCALE_JACOBIAN` - scale by solving a linear system coming from the Jacobian you provided with `SNESSetJacobian()`
1134                                computed at the first iteration of `SNESQN` and at ever restart.
1135 
1136     Options Database Key:
1137 . -snes_qn_scale_type <diagonal,none,scalar,jacobian> - Scaling type
1138 
1139    Level: intermediate
1140 
1141 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNType`, `SNESQNSetType()`, `SNESQNSetRestartType()`, `SNESQNRestartType`
1142 M*/
1143 typedef enum {
1144   SNES_QN_SCALE_DEFAULT  = 0,
1145   SNES_QN_SCALE_NONE     = 1,
1146   SNES_QN_SCALE_SCALAR   = 2,
1147   SNES_QN_SCALE_DIAGONAL = 3,
1148   SNES_QN_SCALE_JACOBIAN = 4
1149 } SNESQNScaleType;
1150 PETSC_EXTERN const char *const SNESQNScaleTypes[];
1151 
1152 /*MC
1153    SNESQNRestartType - the restart approached used by `SNESQN`
1154 
1155    Values:
1156 +   `SNES_QN_RESTART_NONE`     - never restart
1157 .   `SNES_QN_RESTART_POWELL`   - restart based upon descent criteria
1158 -   `SNES_QN_RESTART_PERIODIC` - restart after a fixed number of iterations
1159 
1160   Options Database Keys:
1161 + -snes_qn_restart_type <powell,periodic,none> - set the restart type
1162 - -snes_qn_m <m>                               - sets the number of stored updates and the restart period for periodic
1163 
1164    Level: intermediate
1165 
1166 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNType`, `SNESQNSetType()`, `SNESQNSetRestartType()`, `SNESQNScaleType`
1167 M*/
1168 typedef enum {
1169   SNES_QN_RESTART_DEFAULT  = 0,
1170   SNES_QN_RESTART_NONE     = 1,
1171   SNES_QN_RESTART_POWELL   = 2,
1172   SNES_QN_RESTART_PERIODIC = 3
1173 } SNESQNRestartType;
1174 PETSC_EXTERN const char *const SNESQNRestartTypes[];
1175 
1176 /*MC
1177    SNESQNType - the type used by `SNESQN`
1178 
1179   Values:
1180 +   `SNES_QN_LBFGS`      - LBFGS variant
1181 .   `SNES_QN_BROYDEN`    - Broyden variant
1182 -   `SNES_QN_BADBROYDEN` - Bad Broyden variant
1183 
1184   Options Database Key:
1185 . -snes_qn_type <lbfgs,broyden,badbroyden> - quasi-Newton type
1186 
1187    Level: intermediate
1188 
1189 .seealso: `SNES, `SNESQN`, `SNESQNSetScaleType()`, `SNESQNSetType()`, `SNESQNScaleType`, `SNESQNRestartType`, `SNESQNSetRestartType()`
1190 M*/
1191 typedef enum {
1192   SNES_QN_LBFGS      = 0,
1193   SNES_QN_BROYDEN    = 1,
1194   SNES_QN_BADBROYDEN = 2
1195 } SNESQNType;
1196 PETSC_EXTERN const char *const SNESQNTypes[];
1197 
1198 PETSC_EXTERN PetscErrorCode SNESQNSetType(SNES, SNESQNType);
1199 PETSC_EXTERN PetscErrorCode SNESQNSetScaleType(SNES, SNESQNScaleType);
1200 PETSC_EXTERN PetscErrorCode SNESQNSetRestartType(SNES, SNESQNRestartType);
1201 
1202 PETSC_EXTERN PetscErrorCode SNESNASMGetType(SNES, PCASMType *);
1203 PETSC_EXTERN PetscErrorCode SNESNASMSetType(SNES, PCASMType);
1204 PETSC_EXTERN PetscErrorCode SNESNASMGetSubdomains(SNES, PetscInt *, SNES *[], VecScatter *[], VecScatter *[], VecScatter *[]);
1205 PETSC_EXTERN PetscErrorCode SNESNASMSetSubdomains(SNES, PetscInt, SNES[], VecScatter[], VecScatter[], VecScatter[]);
1206 PETSC_EXTERN PetscErrorCode SNESNASMSetDamping(SNES, PetscReal);
1207 PETSC_EXTERN PetscErrorCode SNESNASMGetDamping(SNES, PetscReal *);
1208 PETSC_EXTERN PetscErrorCode SNESNASMGetSubdomainVecs(SNES, PetscInt *, Vec *[], Vec *[], Vec *[], Vec *[]);
1209 PETSC_EXTERN PetscErrorCode SNESNASMSetComputeFinalJacobian(SNES, PetscBool);
1210 PETSC_EXTERN PetscErrorCode SNESNASMGetSNES(SNES, PetscInt, SNES *);
1211 PETSC_EXTERN PetscErrorCode SNESNASMGetNumber(SNES, PetscInt *);
1212 PETSC_EXTERN PetscErrorCode SNESNASMSetWeight(SNES, Vec);
1213 
1214 /*E
1215   SNESCompositeType - Determines how two or more preconditioners are composed with the `SNESType` of `SNESCOMPOSITE`
1216 
1217   Values:
1218 + `SNES_COMPOSITE_ADDITIVE`        - results from application of all preconditioners are added together
1219 . `SNES_COMPOSITE_MULTIPLICATIVE`  - preconditioners are applied sequentially to the residual freshly
1220                                      computed after the previous preconditioner application
1221 - `SNES_COMPOSITE_ADDITIVEOPTIMAL` - uses a linear combination of the solutions obtained with each preconditioner that approximately minimize the function
1222                                      value at the new iteration.
1223 
1224    Level: beginner
1225 
1226 .seealso: [](sec_pc), `PCCOMPOSITE`, `PCFIELDSPLIT`, `PC`, `PCCompositeSetType()`, `PCCompositeType`
1227 E*/
1228 typedef enum {
1229   SNES_COMPOSITE_ADDITIVE,
1230   SNES_COMPOSITE_MULTIPLICATIVE,
1231   SNES_COMPOSITE_ADDITIVEOPTIMAL
1232 } SNESCompositeType;
1233 PETSC_EXTERN const char *const SNESCompositeTypes[];
1234 
1235 PETSC_EXTERN PetscErrorCode SNESCompositeSetType(SNES, SNESCompositeType);
1236 PETSC_EXTERN PetscErrorCode SNESCompositeAddSNES(SNES, SNESType);
1237 PETSC_EXTERN PetscErrorCode SNESCompositeGetSNES(SNES, PetscInt, SNES *);
1238 PETSC_EXTERN PetscErrorCode SNESCompositeGetNumber(SNES, PetscInt *);
1239 PETSC_EXTERN PetscErrorCode SNESCompositeSetDamping(SNES, PetscInt, PetscReal);
1240 
1241 PETSC_EXTERN PetscErrorCode SNESPatchSetDiscretisationInfo(SNES, PetscInt, DM *, PetscInt *, PetscInt *, const PetscInt **, const PetscInt *, PetscInt, const PetscInt *, PetscInt, const PetscInt *);
1242 PETSC_EXTERN PetscErrorCode SNESPatchSetComputeOperator(SNES, PetscErrorCode (*func)(PC, PetscInt, Vec, Mat, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *);
1243 PETSC_EXTERN PetscErrorCode SNESPatchSetComputeFunction(SNES, PetscErrorCode (*func)(PC, PetscInt, Vec, Vec, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *);
1244 PETSC_EXTERN PetscErrorCode SNESPatchSetConstructType(SNES, PCPatchConstructType, PetscErrorCode (*func)(PC, PetscInt *, IS **, IS *, void *), void *);
1245 PETSC_EXTERN PetscErrorCode SNESPatchSetCellNumbering(SNES, PetscSection);
1246 
1247 /*E
1248     SNESFASType - Determines the type of nonlinear multigrid method that is run.
1249 
1250    Values:
1251 +  `SNES_FAS_MULTIPLICATIVE` (default) - traditional V or W cycle as determined by `SNESFASSetCycles()`
1252 .  `SNES_FAS_ADDITIVE`                 - additive FAS cycle
1253 .  `SNES_FAS_FULL`                     - full FAS cycle
1254 -  `SNES_FAS_KASKADE`                  - Kaskade FAS cycle
1255 
1256    Level: beginner
1257 
1258 .seealso: [](ch_snes), `SNESFAS`, `PCMGSetType()`, `PCMGType`
1259 E*/
1260 typedef enum {
1261   SNES_FAS_MULTIPLICATIVE,
1262   SNES_FAS_ADDITIVE,
1263   SNES_FAS_FULL,
1264   SNES_FAS_KASKADE
1265 } SNESFASType;
1266 PETSC_EXTERN const char *const SNESFASTypes[];
1267 
1268 /* called on the finest level FAS instance*/
1269 PETSC_EXTERN PetscErrorCode SNESFASSetType(SNES, SNESFASType);
1270 PETSC_EXTERN PetscErrorCode SNESFASGetType(SNES, SNESFASType *);
1271 PETSC_EXTERN PetscErrorCode SNESFASSetLevels(SNES, PetscInt, MPI_Comm *);
1272 PETSC_EXTERN PetscErrorCode SNESFASGetLevels(SNES, PetscInt *);
1273 PETSC_EXTERN PetscErrorCode SNESFASGetCycleSNES(SNES, PetscInt, SNES *);
1274 PETSC_EXTERN PetscErrorCode SNESFASSetNumberSmoothUp(SNES, PetscInt);
1275 PETSC_EXTERN PetscErrorCode SNESFASSetNumberSmoothDown(SNES, PetscInt);
1276 PETSC_EXTERN PetscErrorCode SNESFASSetCycles(SNES, PetscInt);
1277 PETSC_EXTERN PetscErrorCode SNESFASSetMonitor(SNES, PetscViewerAndFormat *, PetscBool);
1278 PETSC_EXTERN PetscErrorCode SNESFASSetLog(SNES, PetscBool);
1279 
1280 PETSC_EXTERN PetscErrorCode SNESFASSetGalerkin(SNES, PetscBool);
1281 PETSC_EXTERN PetscErrorCode SNESFASGetGalerkin(SNES, PetscBool *);
1282 PETSC_EXTERN PetscErrorCode SNESFASGalerkinFunctionDefault(SNES, Vec, Vec, void *);
1283 
1284 /* called on any level -- "Cycle" FAS instance */
1285 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmoother(SNES, SNES *);
1286 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmootherUp(SNES, SNES *);
1287 PETSC_EXTERN PetscErrorCode SNESFASCycleGetSmootherDown(SNES, SNES *);
1288 PETSC_EXTERN PetscErrorCode SNESFASCycleGetCorrection(SNES, SNES *);
1289 PETSC_EXTERN PetscErrorCode SNESFASCycleGetInterpolation(SNES, Mat *);
1290 PETSC_EXTERN PetscErrorCode SNESFASCycleGetRestriction(SNES, Mat *);
1291 PETSC_EXTERN PetscErrorCode SNESFASCycleGetInjection(SNES, Mat *);
1292 PETSC_EXTERN PetscErrorCode SNESFASCycleGetRScale(SNES, Vec *);
1293 PETSC_EXTERN PetscErrorCode SNESFASCycleSetCycles(SNES, PetscInt);
1294 PETSC_EXTERN PetscErrorCode SNESFASCycleIsFine(SNES, PetscBool *);
1295 
1296 /* called on the (outer) finest level FAS to set/get parameters on any level instance */
1297 PETSC_EXTERN PetscErrorCode SNESFASSetInterpolation(SNES, PetscInt, Mat);
1298 PETSC_EXTERN PetscErrorCode SNESFASGetInterpolation(SNES, PetscInt, Mat *);
1299 PETSC_EXTERN PetscErrorCode SNESFASSetRestriction(SNES, PetscInt, Mat);
1300 PETSC_EXTERN PetscErrorCode SNESFASGetRestriction(SNES, PetscInt, Mat *);
1301 PETSC_EXTERN PetscErrorCode SNESFASSetInjection(SNES, PetscInt, Mat);
1302 PETSC_EXTERN PetscErrorCode SNESFASGetInjection(SNES, PetscInt, Mat *);
1303 PETSC_EXTERN PetscErrorCode SNESFASSetRScale(SNES, PetscInt, Vec);
1304 PETSC_EXTERN PetscErrorCode SNESFASGetRScale(SNES, PetscInt, Vec *);
1305 PETSC_EXTERN PetscErrorCode SNESFASSetContinuation(SNES, PetscBool);
1306 
1307 PETSC_EXTERN PetscErrorCode SNESFASGetSmoother(SNES, PetscInt, SNES *);
1308 PETSC_EXTERN PetscErrorCode SNESFASGetSmootherUp(SNES, PetscInt, SNES *);
1309 PETSC_EXTERN PetscErrorCode SNESFASGetSmootherDown(SNES, PetscInt, SNES *);
1310 PETSC_EXTERN PetscErrorCode SNESFASGetCoarseSolve(SNES, SNES *);
1311 
1312 /* parameters for full FAS */
1313 PETSC_EXTERN PetscErrorCode SNESFASFullSetDownSweep(SNES, PetscBool);
1314 PETSC_EXTERN PetscErrorCode SNESFASCreateCoarseVec(SNES, Vec *);
1315 PETSC_EXTERN PetscErrorCode SNESFASRestrict(SNES, Vec, Vec);
1316 PETSC_EXTERN PetscErrorCode SNESFASFullSetTotal(SNES, PetscBool);
1317 PETSC_EXTERN PetscErrorCode SNESFASFullGetTotal(SNES, PetscBool *);
1318 
1319 PETSC_EXTERN PetscErrorCode DMPlexSetSNESVariableBounds(DM, SNES);
1320 PETSC_EXTERN PetscErrorCode DMSNESCheckDiscretization(SNES, DM, PetscReal, Vec, PetscReal, PetscReal[]);
1321 PETSC_EXTERN PetscErrorCode DMSNESCheckResidual(SNES, DM, Vec, PetscReal, PetscReal *);
1322 PETSC_EXTERN PetscErrorCode DMSNESCheckJacobian(SNES, DM, Vec, PetscReal, PetscBool *, PetscReal *);
1323 PETSC_EXTERN PetscErrorCode DMSNESCheckFromOptions(SNES, Vec);
1324 PETSC_EXTERN PetscErrorCode DMSNESComputeJacobianAction(DM, Vec, Vec, Vec, void *);
1325 PETSC_EXTERN PetscErrorCode DMSNESCreateJacobianMF(DM, Vec, void *, Mat *);
1326 
1327 PETSC_EXTERN PetscErrorCode SNESNewtonALSetFunction(SNES, SNESFunctionFn *, void *ctx);
1328 PETSC_EXTERN PetscErrorCode SNESNewtonALGetFunction(SNES, SNESFunctionFn **, void **ctx);
1329 PETSC_EXTERN PetscErrorCode SNESNewtonALComputeFunction(SNES, Vec, Vec);
1330 PETSC_EXTERN PetscErrorCode SNESNewtonALGetLoadParameter(SNES, PetscReal *);
1331 
1332 /*MC
1333    SNESNewtonALCorrectionType - the approach used by `SNESNEWTONAL` to determine
1334    the correction to the current increment. While the exact correction satisfies
1335    the constraint surface at every iteration, it also requires solving a quadratic
1336    equation which may not have real roots. Conversely, the normal correction is more
1337    efficient and always yields a real correction and is the default.
1338 
1339    Values:
1340 +   `SNES_NEWTONAL_CORRECTION_EXACT` - choose the correction which exactly satisfies the constraint
1341 -   `SNES_NEWTONAL_CORRECTION_NORMAL` - choose the correction in the updated normal hyper-surface to the constraint surface
1342 
1343    Options Database Key:
1344 . -snes_newtonal_correction_type <exact> - select type from <exact,normal>
1345 
1346    Level: intermediate
1347 
1348 .seealso: `SNES`, `SNESNEWTONAL`, `SNESNewtonALSetCorrectionType()`
1349 M*/
1350 typedef enum {
1351   SNES_NEWTONAL_CORRECTION_EXACT  = 0,
1352   SNES_NEWTONAL_CORRECTION_NORMAL = 1,
1353 } SNESNewtonALCorrectionType;
1354 PETSC_EXTERN const char *const SNESNewtonALCorrectionTypes[];
1355 
1356 PETSC_EXTERN PetscErrorCode SNESNewtonALSetCorrectionType(SNES, SNESNewtonALCorrectionType);
1357