Actual source code: petscsnes.h

      1: /*
      2:     User interface for the nonlinear solvers package.
      3: */
      4: #pragma once

      6: #include <petscksp.h>
      7: #include <petscdmtypes.h>
      8: #include <petscfvtypes.h>
      9: #include <petscdmdatypes.h>
     10: #include <petscsnestypes.h>

     12: /* SUBMANSEC = SNES */

     14: /*J
     15:    SNESType - String with the name of a PETSc `SNES` method. These are all the nonlinear solvers that PETSc provides.

     17:    Level: beginner

     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

     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"

     48: /* Logging support */
     49: PETSC_EXTERN PetscClassId SNES_CLASSID;
     50: PETSC_EXTERN PetscClassId DMSNES_CLASSID;

     52: PETSC_EXTERN PetscErrorCode SNESInitializePackage(void);
     53: PETSC_EXTERN PetscErrorCode SNESFinalizePackage(void);

     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);

     75: PETSC_EXTERN PetscErrorCode SNESSetWorkVecs(SNES, PetscInt);

     77: PETSC_EXTERN PetscErrorCode SNESAddOptionsChecker(PetscErrorCode (*)(SNES));

     79: PETSC_EXTERN PetscErrorCode SNESRegister(const char[], PetscErrorCode (*)(SNES));

     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);

     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: }

    104: #define SNES_FILE_CLASSID 1211224

    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);

    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);

    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 **);

    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);

    149: /*E
    150:    SNESNewtonTRFallbackType - type of fallback in case the solution of the trust-region subproblem is outside of the radius

    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

    157:    Level: intermediate

    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;

    167: PETSC_EXTERN const char *const SNESNewtonTRFallbackTypes[];

    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);

    178: /*E
    179:     SNESNewtonTRQNType - type of quasi-Newton model to use

    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

    186:    Level: intermediate

    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;

    196: PETSC_EXTERN const char *const SNESNewtonTRQNTypes[];

    198: PETSC_EXTERN PetscErrorCode SNESNewtonTRSetQNType(SNES, SNESNewtonTRQNType);

    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 *);

    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);

    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 *);

    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 *);

    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);

    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 *);

    238: PETSC_EXTERN PetscErrorCode SNESMonitorLGRange(SNES, PetscInt, PetscReal, void *);

    240: PETSC_EXTERN PetscErrorCode SNESSetApplicationContext(SNES, void *);
    241: PETSC_EXTERN PetscErrorCode SNESGetApplicationContext(SNES, void *);
    242: PETSC_EXTERN PetscErrorCode SNESSetComputeApplicationContext(SNES, PetscErrorCode (*)(SNES, void **), PetscCtxDestroyFn *);

    244: PETSC_EXTERN PetscErrorCode SNESPythonSetType(SNES, const char[]);
    245: PETSC_EXTERN PetscErrorCode SNESPythonGetType(SNES, const char *[]);

    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 *);

    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

    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()`

    273:    Level: beginner

    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).

    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.

    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.

    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.

    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.

    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.

    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 */

    332:   SNES_CONVERGED_ITERATING = 0
    333: } SNESConvergedReason;
    334: PETSC_EXTERN const char *const *SNESConvergedReasons;

    336: /*MC
    337:    SNES_CONVERGED_FNORM_ABS - 2-norm(F) <= abstol

    339:    Level: beginner

    341: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    342: M*/

    344: /*MC
    345:    SNES_CONVERGED_FNORM_RELATIVE - 2-norm(F) <= rtol*2-norm(F(x_0)) where x_0 is the initial guess

    347:    Level: beginner

    349: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    350: M*/

    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()`

    356:   Options Database Key:
    357:   -snes_stol <stol> - the step tolerance

    359:    Level: beginner

    361: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    362: M*/

    364: /*MC
    365:    SNES_DIVERGED_FUNCTION_COUNT - The user provided function has been called more times then the final
    366:    argument to `SNESSetTolerances()`

    368:    Level: beginner

    370: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    371: M*/

    373: /*MC
    374:    SNES_DIVERGED_DTOL - The norm of the function has increased by a factor of divtol set with `SNESSetDivergenceTolerance()`

    376:    Level: beginner

    378: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`, `SNESSetDivergenceTolerance()`
    379: M*/

    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.

    385:    Level: beginner

    387: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    388: M*/

    390: /*MC
    391:    SNES_DIVERGED_MAX_IT - SNESSolve() has reached the maximum number of iterations requested

    393:    Level: beginner

    395: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    396: M*/

    398: /*MC
    399:    SNES_DIVERGED_LINE_SEARCH - The line search has failed. This only occurs for a `SNES` solvers that use a line search

    401:    Level: beginner

    403: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`, `SNESLineSearch`
    404: M*/

    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

    410:    Level: beginner

    412: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    413: M*/

    415: /*MC
    416:    SNES_CONERGED_ITERATING - this only occurs if `SNESGetConvergedReason()` is called during the `SNESSolve()`

    418:    Level: beginner

    420: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergedReason()`, `SNESConvergedReason`, `SNESSetTolerances()`
    421: M*/

    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);

    431: PETSC_DEPRECATED_FUNCTION(3, 5, 0, "SNESConvergedSkip()", ) static inline void SNESSkipConverged(void)
    432: { /* never called */
    433: }
    434: #define SNESSkipConverged (SNESSkipConverged, SNESConvergedSkip)

    436: /*S
    437:   SNESInitialGuessFn - A prototype of a `SNES` compute initial guess function that would be passed to `SNESSetComputeInitialGuess()`

    439:   Calling Sequence:
    440: + snes  - `SNES` context
    441: . u   - output vector to contain initial guess
    442: - ctx - [optional] user-defined function context

    444:   Level: beginner

    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);

    450: /*S
    451:   SNESFunctionFn - A prototype of a `SNES` evaluation function that would be passed to `SNESSetFunction()`

    453:   Calling Sequence:
    454: + snes  - `SNES` context
    455: . u   - input vector
    456: . F   - function vector
    457: - ctx - [optional] user-defined function context

    459:   Level: beginner

    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);

    465: /*S
    466:   SNESObjectiveFn - A prototype of a `SNES` objective evaluation function that would be passed to `SNESSetObjective()`

    468:   Calling Sequence:
    469: + snes  - `SNES` context
    470: . u   - input vector
    471: . o   - output value
    472: - ctx - [optional] user-defined function context

    474:   Level: beginner

    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);

    480: /*S
    481:   SNESJacobianFn - A prototype of a `SNES` Jacobian evaluation function that would be passed to `SNESSetJacobian()`

    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

    490:   Level: beginner

    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);

    496: /*S
    497:   SNESNGSFn - A prototype of a `SNES` nonlinear Gauss-Seidel function that would be passed to `SNESSetNGS()`

    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

    505:   Level: beginner

    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);

    511: /*S
    512:   SNESUpdateFn - A prototype of a `SNES` update function that would be passed to `SNESSetUpdate()`

    514:   Calling Sequence:
    515: + snes - `SNES` context
    516: - step - the current iteration index

    518:   Level: advanced

    520: .seealso: [](ch_snes), `SNES`, `SNESSetUpdate()`
    521: S*/
    522: PETSC_EXTERN_TYPEDEF typedef PetscErrorCode SNESUpdateFn(SNES snes, PetscInt step);

    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);

    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;

    544: PETSC_EXTERN PetscErrorCode SNESSetObjective(SNES, SNESObjectiveFn *, void *);
    545: PETSC_EXTERN PetscErrorCode SNESGetObjective(SNES, SNESObjectiveFn **, void **);
    546: PETSC_EXTERN PetscErrorCode SNESComputeObjective(SNES, Vec, PetscReal *);

    548: PETSC_EXTERN PetscErrorCode SNESSetUpdate(SNES, SNESUpdateFn *);

    550: /*E
    551:    SNESNormSchedule - Frequency with which the norm is computed during a nonliner solve

    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

    561:    Level: advanced

    563:    Notes:
    564:    Support for these is highly dependent on the solver.

    566:    Some options limit the convergence tests that can be used.

    568:    The `SNES_NORM_NONE` option is most commonly used when the nonlinear solver is being used as a smoother, for example for `SNESFAS`

    570:    This is primarily used to turn off extra norm and function computation
    571:    when the solvers are composed.

    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;

    586: /*MC
    587:    SNES_NORM_NONE - Don't compute function and its L2 norm when possible

    589:    Level: advanced

    591:    Note:
    592:    This is most useful for stationary solvers with a fixed number of iterations used as smoothers.

    594: .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_DEFAULT`
    595: M*/

    597: /*MC
    598:    SNES_NORM_ALWAYS - Compute the function and its L2 norm at each iteration.

    600:    Level: advanced

    602:    Note:
    603:    Most solvers will use this no matter what norm type is passed to them.

    605: .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_NONE`
    606: M*/

    608: /*MC
    609:    SNES_NORM_INITIAL_ONLY - Compute the function and its L2 at iteration 0, but do not update it.

    611:    Level: advanced

    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.

    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).

    620: .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_FINAL_ONLY`, `SNES_NORM_INITIAL_FINAL_ONLY`
    621: M*/

    623: /*MC
    624:    SNES_NORM_FINAL_ONLY - Compute the function and its L2 norm on only the final iteration.

    626:    Level: advanced

    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.

    634: .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_INITIAL_ONLY`, `SNES_NORM_INITIAL_FINAL_ONLY`
    635: M*/

    637: /*MC
    638:    SNES_NORM_INITIAL_FINAL_ONLY - Compute the function and its L2 norm on only the initial and final iterations.

    640:    Level: advanced

    642:    Note:
    643:    This method combines the benefits of `SNES_NORM_INITIAL_ONLY` and `SNES_NORM_FINAL_ONLY`.

    645: .seealso: [](ch_snes), `SNESNormSchedule`, `SNES`, `SNESSetNormSchedule()`, `SNES_NORM_SNES_NORM_INITIAL_ONLY`, `SNES_NORM_FINAL_ONLY`
    646: M*/

    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 *);

    655: /*E
    656:    SNESFunctionType - Type of function computed

    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

    663:    Level: advanced

    665:    Note:
    666:    Support for these is dependent on the solver.

    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;

    678: PETSC_EXTERN PetscErrorCode SNESSetFunctionType(SNES, SNESFunctionType);
    679: PETSC_EXTERN PetscErrorCode SNESGetFunctionType(SNES, SNESFunctionType *);

    681: PETSC_EXTERN PetscErrorCode SNESSetNGS(SNES, SNESNGSFn *, void *);
    682: PETSC_EXTERN PetscErrorCode SNESGetNGS(SNES, SNESNGSFn **, void **);
    683: PETSC_EXTERN PetscErrorCode SNESComputeNGS(SNES, Vec, Vec);

    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 *);

    690: PETSC_EXTERN PetscErrorCode SNESSetAlwaysComputesFinalResidual(SNES, PetscBool);
    691: PETSC_EXTERN PetscErrorCode SNESGetAlwaysComputesFinalResidual(SNES, PetscBool *);

    693: PETSC_EXTERN PetscErrorCode SNESShellGetContext(SNES, void *);
    694: PETSC_EXTERN PetscErrorCode SNESShellSetContext(SNES, void *);
    695: PETSC_EXTERN PetscErrorCode SNESShellSetSolve(SNES, PetscErrorCode (*)(SNES, Vec));

    697: /* --------- Routines specifically for line search methods --------------- */

    699: /*S
    700:    SNESLineSearch - Abstract PETSc object that manages line-search operations for nonlinear solvers

    702:    Level: beginner

    704: .seealso: [](ch_snes), `SNESLineSearchType`, `SNESLineSearchCreate()`, `SNESLineSearchSetType()`, `SNES`
    705: S*/
    706: typedef struct _p_LineSearch *SNESLineSearch;

    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.

    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

    721:    Level: beginner

    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.

    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"

    741: PETSC_EXTERN PetscFunctionList SNESList;
    742: PETSC_EXTERN PetscClassId      SNESLINESEARCH_CLASSID;
    743: PETSC_EXTERN PetscFunctionList SNESLineSearchList;

    745: #define SNES_LINESEARCH_ORDER_LINEAR    1
    746: #define SNES_LINESEARCH_ORDER_QUADRATIC 2
    747: #define SNES_LINESEARCH_ORDER_CUBIC     3

    749: /*S
    750:   SNESLineSearchVIProjectFn - A prototype of a `SNES` function that projects a vector onto the VI bounds, passed to `SNESLineSearchSetVIFunctions()`

    752:   Calling Sequence:
    753: + snes  - `SNES` context
    754: - u     - the vector to project to the bounds

    756:   Level: advanced

    758:   Note:
    759:   The deprecated `SNESLineSearchVIProjectFunc` still works as a replacement for `SNESLineSearchVIProjectFn` *.

    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*", );

    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()`

    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

    776:   Level: advanced

    778:   Note:
    779:   The deprecated `SNESLineSearchVINormFunc` still works as a replacement for `SNESLineSearchVINormFn` *.

    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*", );

    786: /*S
    787:   SNESLineSearchVIDirDerivFn - A prototype of a `SNES` function that computes the directional derivative considering the VI bounds, passed to `SNESLineSearchSetVIFunctions()`

    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

    796:   Level: advanced

    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);

    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*", );

    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);

    821: /* set the functions for precheck and postcheck */

    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);

    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);

    829: /* set the functions for VI-specific line search operations */

    831: PETSC_EXTERN PetscErrorCode SNESLineSearchSetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn *, SNESLineSearchVINormFn *, SNESLineSearchVIDirDerivFn *);
    832: PETSC_EXTERN PetscErrorCode SNESLineSearchGetVIFunctions(SNESLineSearch, SNESLineSearchVIProjectFn **, SNESLineSearchVINormFn **, SNESLineSearchVIDirDerivFn **);

    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 *);

    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);

    842: PETSC_EXTERN PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch, Vec, Vec, PetscBool *, void *);

    844: PETSC_EXTERN PetscErrorCode SNESLineSearchGetLambda(SNESLineSearch, PetscReal *);
    845: PETSC_EXTERN PetscErrorCode SNESLineSearchSetLambda(SNESLineSearch, PetscReal);

    847: PETSC_EXTERN PetscErrorCode SNESLineSearchGetDamping(SNESLineSearch, PetscReal *);
    848: PETSC_EXTERN PetscErrorCode SNESLineSearchSetDamping(SNESLineSearch, PetscReal);

    850: PETSC_EXTERN PetscErrorCode SNESLineSearchGetOrder(SNESLineSearch, PetscInt *);
    851: PETSC_EXTERN PetscErrorCode SNESLineSearchSetOrder(SNESLineSearch, PetscInt);

    853: /*E
    854:     SNESLineSearchReason - indication if the line search has succeeded or failed and why

    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`

    865:    Level: intermediate

    867:    Developer Note:
    868:    Some of these reasons overlap with values of `SNESConvergedReason`

    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;

    882: PETSC_EXTERN PetscErrorCode SNESLineSearchGetReason(SNESLineSearch, SNESLineSearchReason *);
    883: PETSC_EXTERN PetscErrorCode SNESLineSearchSetReason(SNESLineSearch, SNESLineSearchReason);

    885: PETSC_EXTERN PetscErrorCode SNESLineSearchGetVecs(SNESLineSearch, Vec *, Vec *, Vec *, Vec *, Vec *);
    886: PETSC_EXTERN PetscErrorCode SNESLineSearchSetVecs(SNESLineSearch, Vec, Vec, Vec, Vec, Vec);

    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);

    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 *);

    901: PETSC_EXTERN PetscErrorCode SNESLineSearchAppendOptionsPrefix(SNESLineSearch, const char[]);
    902: PETSC_EXTERN PetscErrorCode SNESLineSearchGetOptionsPrefix(SNESLineSearch, const char *[]);

    904: /* Shell interface functions */
    905: PETSC_EXTERN PetscErrorCode SNESLineSearchShellSetApply(SNESLineSearch, SNESLineSearchShellApplyFn *, void *);
    906: PETSC_EXTERN PetscErrorCode SNESLineSearchShellGetApply(SNESLineSearch, SNESLineSearchShellApplyFn **, void **);

    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: }

    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: }

    918: /* BT interface functions */
    919: PETSC_EXTERN PetscErrorCode SNESLineSearchBTSetAlpha(SNESLineSearch, PetscReal);
    920: PETSC_EXTERN PetscErrorCode SNESLineSearchBTGetAlpha(SNESLineSearch, PetscReal *);

    922: /*register line search types */
    923: PETSC_EXTERN PetscErrorCode SNESLineSearchRegister(const char[], PetscErrorCode (*)(SNESLineSearch));

    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);

    939: PETSC_EXTERN PetscErrorCode SNESTestLocalMin(SNES);

    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);

    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 *);

    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: }

    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);

    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 *);

    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 *);

    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 *);

    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 *);

    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 **);

    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 *[]);

    1017: /*J
    1018:    SNESMSType - String with the name of a PETSc `SNESMS` method.

    1020:    Level: intermediate

    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"

    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);

    1045: /*MC
    1046:    SNESNGMRESRestartType - the restart approach used by `SNESNGMRES`

    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

    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

    1057:    Level: intermediate

    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[];

    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.

    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

    1078:   Options Database Key:
    1079: . -snes_ngmres_select_type<difference,none,linesearch> - select type

    1081:    Level: intermediate

    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[];

    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 *);

    1098: /*MC
    1099:    SNESNCGType - the conjugate update approach for `SNESNCG`

    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

    1108:   Options Database Key:
    1109: . -snes_ncg_type<fr,prp,hs,dy,cd> - select type

    1111:    Level: intermediate

    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[];

    1124: PETSC_EXTERN PetscErrorCode SNESNCGSetType(SNES, SNESNCGType);

    1126: /*MC
    1127:    SNESQNScaleType - the scaling type used by `SNESQN`

    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.

    1136:     Options Database Key:
    1137: . -snes_qn_scale_type <diagonal,none,scalar,jacobian> - Scaling type

    1139:    Level: intermediate

    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[];

    1152: /*MC
    1153:    SNESQNRestartType - the restart approached used by `SNESQN`

    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

    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

    1164:    Level: intermediate

    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[];

    1176: /*MC
    1177:    SNESQNType - the type used by `SNESQN`

    1179:   Values:
    1180: +   `SNES_QN_LBFGS`      - LBFGS variant
    1181: .   `SNES_QN_BROYDEN`    - Broyden variant
    1182: -   `SNES_QN_BADBROYDEN` - Bad Broyden variant

    1184:   Options Database Key:
    1185: . -snes_qn_type <lbfgs,broyden,badbroyden> - quasi-Newton type

    1187:    Level: intermediate

    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[];

    1198: PETSC_EXTERN PetscErrorCode SNESQNSetType(SNES, SNESQNType);
    1199: PETSC_EXTERN PetscErrorCode SNESQNSetScaleType(SNES, SNESQNScaleType);
    1200: PETSC_EXTERN PetscErrorCode SNESQNSetRestartType(SNES, SNESQNRestartType);

    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);

    1214: /*E
    1215:   SNESCompositeType - Determines how two or more preconditioners are composed with the `SNESType` of `SNESCOMPOSITE`

    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.

    1224:    Level: beginner

    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[];

    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);

    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);

    1247: /*E
    1248:     SNESFASType - Determines the type of nonlinear multigrid method that is run.

    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

    1256:    Level: beginner

    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[];

    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);

    1280: PETSC_EXTERN PetscErrorCode SNESFASSetGalerkin(SNES, PetscBool);
    1281: PETSC_EXTERN PetscErrorCode SNESFASGetGalerkin(SNES, PetscBool *);
    1282: PETSC_EXTERN PetscErrorCode SNESFASGalerkinFunctionDefault(SNES, Vec, Vec, void *);

    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 *);

    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);

    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 *);

    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 *);

    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 *);

    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 *);

    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.

    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

    1343:    Options Database Key:
    1344: . -snes_newtonal_correction_type <exact> - select type from <exact,normal>

    1346:    Level: intermediate

    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[];

    1356: PETSC_EXTERN PetscErrorCode SNESNewtonALSetCorrectionType(SNES, SNESNewtonALCorrectionType);