petsc/include/petscksp.h

/*
   Defines the interface functions for the Krylov subspace accelerators.
*/
#ifndef PETSCKSP_H
#define PETSCKSP_H

#include <petscpc.h>

/* SUBMANSEC = KSP */

PETSC_EXTERN PetscErrorCode KSPInitializePackage(void);

/*S
     KSP - Abstract PETSc object that manages all Krylov methods. This is the object that manages the
         linear solves in PETSc (even those such as direct solvers that do no use Krylov accelerators).

   Level: beginner

   Note:
    When a direct solver is used, but no Krylov solver is used, the `KSP` object is still used but with a
    `KSPType` of `KSPPREONLY`, meaning that only application of the preconditioner is used as the linear solver.

.seealso: [](chapter_ksp), `KSPCreate()`, `KSPSetType()`, `KSPType`, `SNES`, `TS`, `PC`, `KSP`, `KSPDestroy()`, `KSPCG`, `KSPGMRES`
S*/
typedef struct _p_KSP *KSP;

/*J
    KSPType - String with the name of a PETSc Krylov method.

   Level: beginner

.seealso: [](chapter_ksp), `KSPSetType()`, `KSP`, `KSPRegister()`, `KSPCreate()`, `KSPSetFromOptions()`
J*/
typedef const char *KSPType;
#define KSPRICHARDSON "richardson"
#define KSPCHEBYSHEV  "chebyshev"
#define KSPCG         "cg"
#define KSPGROPPCG    "groppcg"
#define KSPPIPECG     "pipecg"
#define KSPPIPECGRR   "pipecgrr"
#define KSPPIPELCG    "pipelcg"
#define KSPPIPEPRCG   "pipeprcg"
#define KSPPIPECG2    "pipecg2"
#define KSPCGNE       "cgne"
#define KSPNASH       "nash"
#define KSPSTCG       "stcg"
#define KSPGLTR       "gltr"
#define KSPCGNASH     PETSC_DEPRECATED_MACRO("GCC warning \"KSPCGNASH macro is deprecated use KSPNASH (since version 3.11)\"") "nash"
#define KSPCGSTCG     PETSC_DEPRECATED_MACRO("GCC warning \"KSPCGSTCG macro is deprecated use KSPSTCG (since version 3.11)\"") "stcg"
#define KSPCGGLTR     PETSC_DEPRECATED_MACRO("GCC warning \"KSPCGGLTR macro is deprecated use KSPSGLTR (since version 3.11)\"") "gltr"
#define KSPFCG        "fcg"
#define KSPPIPEFCG    "pipefcg"
#define KSPGMRES      "gmres"
#define KSPPIPEFGMRES "pipefgmres"
#define KSPFGMRES     "fgmres"
#define KSPLGMRES     "lgmres"
#define KSPDGMRES     "dgmres"
#define KSPPGMRES     "pgmres"
#define KSPTCQMR      "tcqmr"
#define KSPBCGS       "bcgs"
#define KSPIBCGS      "ibcgs"
#define KSPQMRCGS     "qmrcgs"
#define KSPFBCGS      "fbcgs"
#define KSPFBCGSR     "fbcgsr"
#define KSPBCGSL      "bcgsl"
#define KSPPIPEBCGS   "pipebcgs"
#define KSPCGS        "cgs"
#define KSPTFQMR      "tfqmr"
#define KSPCR         "cr"
#define KSPPIPECR     "pipecr"
#define KSPLSQR       "lsqr"
#define KSPPREONLY    "preonly"
#define KSPNONE       "none"
#define KSPQCG        "qcg"
#define KSPBICG       "bicg"
#define KSPMINRES     "minres"
#define KSPSYMMLQ     "symmlq"
#define KSPLCD        "lcd"
#define KSPPYTHON     "python"
#define KSPGCR        "gcr"
#define KSPPIPEGCR    "pipegcr"
#define KSPTSIRM      "tsirm"
#define KSPCGLS       "cgls"
#define KSPFETIDP     "fetidp"
#define KSPHPDDM      "hpddm"

/* Logging support */
PETSC_EXTERN PetscClassId KSP_CLASSID;
PETSC_EXTERN PetscClassId KSPGUESS_CLASSID;
PETSC_EXTERN PetscClassId DMKSP_CLASSID;

PETSC_EXTERN PetscErrorCode KSPCreate(MPI_Comm, KSP *);
PETSC_EXTERN PetscErrorCode KSPSetType(KSP, KSPType);
PETSC_EXTERN PetscErrorCode KSPGetType(KSP, KSPType *);
PETSC_EXTERN PetscErrorCode KSPSetUp(KSP);
PETSC_EXTERN PetscErrorCode KSPSetUpOnBlocks(KSP);
PETSC_EXTERN PetscErrorCode KSPSolve(KSP, Vec, Vec);
PETSC_EXTERN PetscErrorCode KSPSolveTranspose(KSP, Vec, Vec);
PETSC_EXTERN PetscErrorCode KSPSetUseExplicitTranspose(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPMatSolve(KSP, Mat, Mat);
PETSC_EXTERN PetscErrorCode KSPSetMatSolveBatchSize(KSP, PetscInt);
PETSC_DEPRECATED_FUNCTION("Use KSPSetMatSolveBatchSize() (since version 3.15)") static inline PetscErrorCode KSPSetMatSolveBlockSize(KSP ksp, PetscInt n)
{
  return KSPSetMatSolveBatchSize(ksp, n);
}
PETSC_EXTERN PetscErrorCode KSPGetMatSolveBatchSize(KSP, PetscInt *);
PETSC_DEPRECATED_FUNCTION("Use KSPGetMatSolveBatchSize() (since version 3.15)") static inline PetscErrorCode KSPGetMatSolveBlockSize(KSP ksp, PetscInt *n)
{
  return KSPGetMatSolveBatchSize(ksp, n);
}
PETSC_EXTERN PetscErrorCode KSPReset(KSP);
PETSC_EXTERN PetscErrorCode KSPResetViewers(KSP);
PETSC_EXTERN PetscErrorCode KSPDestroy(KSP *);
PETSC_EXTERN PetscErrorCode KSPSetReusePreconditioner(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetReusePreconditioner(KSP, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPSetSkipPCSetFromOptions(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPCheckSolve(KSP, PC, Vec);

PETSC_EXTERN PetscFunctionList KSPList;
PETSC_EXTERN PetscFunctionList KSPGuessList;
PETSC_EXTERN PetscFunctionList KSPMonitorList;
PETSC_EXTERN PetscFunctionList KSPMonitorCreateList;
PETSC_EXTERN PetscFunctionList KSPMonitorDestroyList;
PETSC_EXTERN PetscErrorCode    KSPRegister(const char[], PetscErrorCode (*)(KSP));
PETSC_EXTERN PetscErrorCode KSPMonitorRegister(const char[], PetscViewerType, PetscViewerFormat, PetscErrorCode (*)(KSP, PetscInt, PetscReal, PetscViewerAndFormat *), PetscErrorCode (*)(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **), PetscErrorCode (*)(PetscViewerAndFormat **));

PETSC_EXTERN PetscErrorCode KSPSetPCSide(KSP, PCSide);
PETSC_EXTERN PetscErrorCode KSPGetPCSide(KSP, PCSide *);
PETSC_EXTERN PetscErrorCode KSPSetTolerances(KSP, PetscReal, PetscReal, PetscReal, PetscInt);
PETSC_EXTERN PetscErrorCode KSPGetTolerances(KSP, PetscReal *, PetscReal *, PetscReal *, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPSetInitialGuessNonzero(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetInitialGuessNonzero(KSP, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPSetErrorIfNotConverged(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetErrorIfNotConverged(KSP, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPSetComputeEigenvalues(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPSetComputeRitz(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetComputeEigenvalues(KSP, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPSetComputeSingularValues(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetComputeSingularValues(KSP, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPGetRhs(KSP, Vec *);
PETSC_EXTERN PetscErrorCode KSPGetSolution(KSP, Vec *);
PETSC_EXTERN PetscErrorCode KSPGetResidualNorm(KSP, PetscReal *);
PETSC_EXTERN PetscErrorCode KSPGetIterationNumber(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPGetTotalIterations(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPCreateVecs(KSP, PetscInt, Vec **, PetscInt, Vec **);
PETSC_DEPRECATED_FUNCTION("Use KSPCreateVecs() (since version 3.6)") static inline PetscErrorCode KSPGetVecs(KSP ksp, PetscInt n, Vec **x, PetscInt m, Vec **y)
{
  return KSPCreateVecs(ksp, n, x, m, y);
}

PETSC_EXTERN PetscErrorCode KSPSetPreSolve(KSP, PetscErrorCode (*)(KSP, Vec, Vec, void *), void *);
PETSC_EXTERN PetscErrorCode KSPSetPostSolve(KSP, PetscErrorCode (*)(KSP, Vec, Vec, void *), void *);

PETSC_EXTERN PetscErrorCode KSPSetPC(KSP, PC);
PETSC_EXTERN PetscErrorCode KSPGetPC(KSP, PC *);

PETSC_EXTERN PetscErrorCode KSPMonitor(KSP, PetscInt, PetscReal);
PETSC_EXTERN PetscErrorCode KSPMonitorSet(KSP, PetscErrorCode (*)(KSP, PetscInt, PetscReal, void *), void *, PetscErrorCode (*)(void **));
PETSC_EXTERN PetscErrorCode KSPMonitorCancel(KSP);
PETSC_EXTERN PetscErrorCode KSPGetMonitorContext(KSP, void *);
PETSC_EXTERN PetscErrorCode KSPGetResidualHistory(KSP, const PetscReal *[], PetscInt *);
PETSC_EXTERN PetscErrorCode KSPSetResidualHistory(KSP, PetscReal[], PetscInt, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetErrorHistory(KSP, const PetscReal *[], PetscInt *);
PETSC_EXTERN PetscErrorCode KSPSetErrorHistory(KSP, PetscReal[], PetscInt, PetscBool);

PETSC_EXTERN PetscErrorCode KSPBuildSolutionDefault(KSP, Vec, Vec *);
PETSC_EXTERN PetscErrorCode KSPBuildResidualDefault(KSP, Vec, Vec, Vec *);
PETSC_EXTERN PetscErrorCode KSPDestroyDefault(KSP);
PETSC_EXTERN PetscErrorCode KSPSetWorkVecs(KSP, PetscInt);

PETSC_EXTERN PetscErrorCode PCKSPGetKSP(PC, KSP *);
PETSC_EXTERN PetscErrorCode PCKSPSetKSP(PC, KSP);
PETSC_EXTERN PetscErrorCode PCBJacobiGetSubKSP(PC, PetscInt *, PetscInt *, KSP *[]);
PETSC_EXTERN PetscErrorCode PCASMGetSubKSP(PC, PetscInt *, PetscInt *, KSP *[]);
PETSC_EXTERN PetscErrorCode PCGASMGetSubKSP(PC, PetscInt *, PetscInt *, KSP *[]);
PETSC_EXTERN PetscErrorCode PCFieldSplitGetSubKSP(PC, PetscInt *, KSP *[]);
PETSC_EXTERN PetscErrorCode PCFieldSplitSchurGetSubKSP(PC, PetscInt *, KSP *[]);
PETSC_EXTERN PetscErrorCode PCMGGetSmoother(PC, PetscInt, KSP *);
PETSC_EXTERN PetscErrorCode PCMGGetSmootherDown(PC, PetscInt, KSP *);
PETSC_EXTERN PetscErrorCode PCMGGetSmootherUp(PC, PetscInt, KSP *);
PETSC_EXTERN PetscErrorCode PCMGGetCoarseSolve(PC, KSP *);
PETSC_EXTERN PetscErrorCode PCGalerkinGetKSP(PC, KSP *);
PETSC_EXTERN PetscErrorCode PCDeflationGetCoarseKSP(PC, KSP *);
/*
  PCMGCoarseList contains the list of coarse space constructor currently registered
  These are added with PCMGRegisterCoarseSpaceConstructor()
*/
PETSC_EXTERN PetscFunctionList PCMGCoarseList;
PETSC_EXTERN PetscErrorCode    PCMGRegisterCoarseSpaceConstructor(const char[], PetscErrorCode (*)(PC, PetscInt, DM, KSP, PetscInt, Mat, Mat *));
PETSC_EXTERN PetscErrorCode    PCMGGetCoarseSpaceConstructor(const char[], PetscErrorCode (**)(PC, PetscInt, DM, KSP, PetscInt, Mat, Mat *));

PETSC_EXTERN PetscErrorCode KSPBuildSolution(KSP, Vec, Vec *);
PETSC_EXTERN PetscErrorCode KSPBuildResidual(KSP, Vec, Vec, Vec *);

PETSC_EXTERN PetscErrorCode KSPRichardsonSetScale(KSP, PetscReal);
PETSC_EXTERN PetscErrorCode KSPRichardsonSetSelfScale(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPChebyshevSetEigenvalues(KSP, PetscReal, PetscReal);
PETSC_EXTERN PetscErrorCode KSPChebyshevEstEigSet(KSP, PetscReal, PetscReal, PetscReal, PetscReal);
PETSC_EXTERN PetscErrorCode KSPChebyshevEstEigSetUseNoisy(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPChebyshevEstEigGetKSP(KSP, KSP *);
PETSC_EXTERN PetscErrorCode KSPComputeExtremeSingularValues(KSP, PetscReal *, PetscReal *);
PETSC_EXTERN PetscErrorCode KSPComputeEigenvalues(KSP, PetscInt, PetscReal[], PetscReal[], PetscInt *);
PETSC_EXTERN PetscErrorCode KSPComputeEigenvaluesExplicitly(KSP, PetscInt, PetscReal[], PetscReal[]);
PETSC_EXTERN PetscErrorCode KSPComputeRitz(KSP, PetscBool, PetscBool, PetscInt *, Vec[], PetscReal[], PetscReal[]);

/*E

  KSPFCDTruncationType - Define how stored directions are used to orthogonalize in flexible conjugate directions (FCD) methods

  Values:
+ `KSP_FCD_TRUNC_TYPE_STANDARD` - uses all (up to mmax) stored directions
- `KSP_FCD_TRUNC_TYPE_NOTAY` - uses the last max(1,mod(i,mmax)) stored directions at iteration i=0,1..

   Level: intermediate

.seealso: [](chapter_ksp), `KSP`, `KSPFCG`, `KSPPIPEFCG`, `KSPPIPEGCR`, `KSPFCGSetTruncationType()`, `KSPFCGGetTruncationType()`
E*/
typedef enum {
  KSP_FCD_TRUNC_TYPE_STANDARD,
  KSP_FCD_TRUNC_TYPE_NOTAY
} KSPFCDTruncationType;
PETSC_EXTERN const char *const KSPFCDTruncationTypes[];

PETSC_EXTERN PetscErrorCode KSPFCGSetMmax(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPFCGGetMmax(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPFCGSetNprealloc(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPFCGGetNprealloc(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPFCGSetTruncationType(KSP, KSPFCDTruncationType);
PETSC_EXTERN PetscErrorCode KSPFCGGetTruncationType(KSP, KSPFCDTruncationType *);

PETSC_EXTERN PetscErrorCode KSPPIPEFCGSetMmax(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPPIPEFCGGetMmax(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPPIPEFCGSetNprealloc(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPPIPEFCGGetNprealloc(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPPIPEFCGSetTruncationType(KSP, KSPFCDTruncationType);
PETSC_EXTERN PetscErrorCode KSPPIPEFCGGetTruncationType(KSP, KSPFCDTruncationType *);

PETSC_EXTERN PetscErrorCode KSPPIPEGCRSetMmax(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRGetMmax(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRSetNprealloc(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRGetNprealloc(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRSetTruncationType(KSP, KSPFCDTruncationType);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRGetTruncationType(KSP, KSPFCDTruncationType *);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRSetUnrollW(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPPIPEGCRGetUnrollW(KSP, PetscBool *);

PETSC_EXTERN PetscErrorCode KSPGMRESSetRestart(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPGMRESGetRestart(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPGMRESSetHapTol(KSP, PetscReal);
PETSC_EXTERN PetscErrorCode KSPGMRESSetBreakdownTolerance(KSP, PetscReal);

PETSC_EXTERN PetscErrorCode KSPGMRESSetPreAllocateVectors(KSP);
PETSC_EXTERN PetscErrorCode KSPGMRESSetOrthogonalization(KSP, PetscErrorCode (*)(KSP, PetscInt));
PETSC_EXTERN PetscErrorCode KSPGMRESGetOrthogonalization(KSP, PetscErrorCode (**)(KSP, PetscInt));
PETSC_EXTERN PetscErrorCode KSPGMRESModifiedGramSchmidtOrthogonalization(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPGMRESClassicalGramSchmidtOrthogonalization(KSP, PetscInt);

PETSC_EXTERN PetscErrorCode KSPLGMRESSetAugDim(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPLGMRESSetConstant(KSP);

PETSC_EXTERN PetscErrorCode KSPPIPEFGMRESSetShift(KSP, PetscScalar);

PETSC_EXTERN PetscErrorCode KSPGCRSetRestart(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPGCRGetRestart(KSP, PetscInt *);
PETSC_EXTERN PetscErrorCode KSPGCRSetModifyPC(KSP, PetscErrorCode (*)(KSP, PetscInt, PetscReal, void *), void *, PetscErrorCode (*)(void *));

PETSC_EXTERN PetscErrorCode KSPFETIDPGetInnerBDDC(KSP, PC *);
PETSC_EXTERN PetscErrorCode KSPFETIDPSetInnerBDDC(KSP, PC);
PETSC_EXTERN PetscErrorCode KSPFETIDPGetInnerKSP(KSP, KSP *);
PETSC_EXTERN PetscErrorCode KSPFETIDPSetPressureOperator(KSP, Mat);

PETSC_EXTERN PetscErrorCode KSPHPDDMSetDeflationMat(KSP, Mat);
PETSC_EXTERN PetscErrorCode KSPHPDDMGetDeflationMat(KSP, Mat *);
#if PetscDefined(HAVE_HPDDM)
PETSC_DEPRECATED_FUNCTION("Use KSPHPDDMSetDeflationMat() (since version 3.18)") static inline PetscErrorCode KSPHPDDMSetDeflationSpace(KSP ksp, Mat U)
{
  return KSPHPDDMSetDeflationMat(ksp, U);
}
PETSC_DEPRECATED_FUNCTION("Use KSPHPDDMGetDeflationMat() (since version 3.18)") static inline PetscErrorCode KSPHPDDMGetDeflationSpace(KSP ksp, Mat *U)
{
  return KSPHPDDMGetDeflationMat(ksp, U);
}
#endif
PETSC_DEPRECATED_FUNCTION("Use KSPMatSolve() (since version 3.14)") static inline PetscErrorCode KSPHPDDMMatSolve(KSP ksp, Mat B, Mat X)
{
  return KSPMatSolve(ksp, B, X);
}
/*E
    KSPHPDDMType - Type of Krylov method used by `KSPHPDDM`

    Level: intermediate

    Values:
+   `KSP_HPDDM_TYPE_GMRES` (default) - Generalized Minimal Residual method
.   `KSP_HPDDM_TYPE_BGMRES` - block GMRES
.   `KSP_HPDDM_TYPE_CG` - Conjugate Gradient
.   `KSP_HPDDM_TYPE_BCG` - block CG
.   `KSP_HPDDM_TYPE_GCRODR` - Generalized Conjugate Residual method with inner Orthogonalization and Deflated Restarting
.   `KSP_HPDDM_TYPE_BGCRODR` - block GCRODR
.   `KSP_HPDDM_TYPE_BFBCG` - breakdown-free BCG
-   `KSP_HPDDM_TYPE_PREONLY` - apply the preconditioner only

.seealso: [](chapter_ksp), `KSPHPDDM`, `KSPHPDDMSetType()`
E*/
typedef enum {
  KSP_HPDDM_TYPE_GMRES   = 0,
  KSP_HPDDM_TYPE_BGMRES  = 1,
  KSP_HPDDM_TYPE_CG      = 2,
  KSP_HPDDM_TYPE_BCG     = 3,
  KSP_HPDDM_TYPE_GCRODR  = 4,
  KSP_HPDDM_TYPE_BGCRODR = 5,
  KSP_HPDDM_TYPE_BFBCG   = 6,
  KSP_HPDDM_TYPE_PREONLY = 7
} KSPHPDDMType;
PETSC_EXTERN const char *const KSPHPDDMTypes[];

/*E
    KSPHPDDMPrecision - Precision of Krylov bases used by `KSPHPDDM`

    Level: intermediate

    Values:
+   `KSP_HPDDM_PRECISION_HALF` - default when PETSc is configured `--with-precision=__fp16`
.   `KSP_HPDDM_PRECISION_SINGLE` - default when PETSc is configured `--with-precision=single`
.   `KSP_HPDDM_PRECISION_DOUBLE` - default when PETSc is configured `--with-precision=double`
-   `KSP_HPDDM_PRECISION_QUADRUPLE` - default when PETSc is configured `--with-precision=__float128`

.seealso: [](chapter_ksp), `KSP`, `KSPHPDDM`
E*/
typedef enum {
  KSP_HPDDM_PRECISION_HALF      = 0,
  KSP_HPDDM_PRECISION_SINGLE    = 1,
  KSP_HPDDM_PRECISION_DOUBLE    = 2,
  KSP_HPDDM_PRECISION_QUADRUPLE = 3
} KSPHPDDMPrecision;
PETSC_EXTERN PetscErrorCode KSPHPDDMSetType(KSP, KSPHPDDMType);
PETSC_EXTERN PetscErrorCode KSPHPDDMGetType(KSP, KSPHPDDMType *);

/*E
    KSPGMRESCGSRefinementType - How the classical (unmodified) Gram-Schmidt is performed.

   Level: advanced

    Values:
+   `KSP_GMRES_CGS_REFINE_NEVER` - one step of classical Gram-Schmidt
.   `KSP_GMRES_CGS_REFINE_IFNEEDED` - a second step is performed if the first step does not satisfy some criteria
-   `KSP_GMRES_CGS_REFINE_ALWAYS` - always perform two steps

.seealso: [](chapter_ksp), `KSP`, `KSPGMRESClassicalGramSchmidtOrthogonalization()`, `KSPGMRESSetOrthogonalization()`,
          `KSPGMRESGetOrthogonalization()`,
          `KSPGMRESSetCGSRefinementType()`, `KSPGMRESGetCGSRefinementType()`, `KSPGMRESModifiedGramSchmidtOrthogonalization()`
E*/
typedef enum {
  KSP_GMRES_CGS_REFINE_NEVER,
  KSP_GMRES_CGS_REFINE_IFNEEDED,
  KSP_GMRES_CGS_REFINE_ALWAYS
} KSPGMRESCGSRefinementType;
PETSC_EXTERN const char *const KSPGMRESCGSRefinementTypes[];
/*MC
    KSP_GMRES_CGS_REFINE_NEVER - Do the classical (unmodified) Gram-Schmidt process

   Level: advanced

   Note:
   Possibly unstable, but the fastest to compute

.seealso: [](chapter_ksp), `KSPGMRESCGSRefinementType`, `KSPGMRESClassicalGramSchmidtOrthogonalization()`, `KSPGMRESSetOrthogonalization()`,
          `KSP`, `KSPGMRESGetOrthogonalization()`,
          `KSPGMRESSetCGSRefinementType()`, `KSPGMRESGetCGSRefinementType()`, `KSP_GMRES_CGS_REFINE_IFNEEDED`, `KSP_GMRES_CGS_REFINE_ALWAYS`,
          `KSPGMRESModifiedGramSchmidtOrthogonalization()`
M*/

/*MC
    KSP_GMRES_CGS_REFINE_IFNEEDED - Do the classical (unmodified) Gram-Schmidt process and one step of
          iterative refinement if an estimate of the orthogonality of the resulting vectors indicates
          poor orthogonality.

   Level: advanced

   Note:
   This is slower than `KSP_GMRES_CGS_REFINE_NEVER` because it requires an extra norm computation to
   estimate the orthogonality but is more stable.

.seealso: [](chapter_ksp), `KSPGMRESCGSRefinementType`, `KSPGMRESClassicalGramSchmidtOrthogonalization()`, `KSPGMRESSetOrthogonalization()`,
          `KSP`, `KSPGMRESGetOrthogonalization()`,
          `KSPGMRESSetCGSRefinementType()`, `KSPGMRESGetCGSRefinementType()`, `KSP_GMRES_CGS_REFINE_NEVER`, `KSP_GMRES_CGS_REFINE_ALWAYS`,
          `KSPGMRESModifiedGramSchmidtOrthogonalization()`
M*/

/*MC
    KSP_GMRES_CGS_REFINE_NEVER - Do two steps of the classical (unmodified) Gram-Schmidt process.

   Level: advanced

   Notes:
   This is roughly twice the cost of `KSP_GMRES_CGS_REFINE_NEVER` because it performs the process twice
   but it saves the extra norm calculation needed by `KSP_GMRES_CGS_REFINE_IFNEEDED`.

   You should only use this if you absolutely know that the iterative refinement is needed.

.seealso: [](chapter_ksp), `KSPGMRESCGSRefinementType`, `KSPGMRESClassicalGramSchmidtOrthogonalization()`, `KSPGMRESSetOrthogonalization()`,
          `KSP`, `KSPGMRESGetOrthogonalization()`,
          `KSPGMRESSetCGSRefinementType()`, `KSPGMRESGetCGSRefinementType()`, `KSP_GMRES_CGS_REFINE_IFNEEDED`, `KSP_GMRES_CGS_REFINE_ALWAYS`,
          `KSPGMRESModifiedGramSchmidtOrthogonalization()`
M*/

PETSC_EXTERN PetscErrorCode KSPGMRESSetCGSRefinementType(KSP, KSPGMRESCGSRefinementType);
PETSC_EXTERN PetscErrorCode KSPGMRESGetCGSRefinementType(KSP, KSPGMRESCGSRefinementType *);

PETSC_EXTERN PetscErrorCode KSPFGMRESModifyPCNoChange(KSP, PetscInt, PetscInt, PetscReal, void *);
PETSC_EXTERN PetscErrorCode KSPFGMRESModifyPCKSP(KSP, PetscInt, PetscInt, PetscReal, void *);
PETSC_EXTERN PetscErrorCode KSPFGMRESSetModifyPC(KSP, PetscErrorCode (*)(KSP, PetscInt, PetscInt, PetscReal, void *), void *, PetscErrorCode (*)(void *));

PETSC_EXTERN PetscErrorCode KSPQCGSetTrustRegionRadius(KSP, PetscReal);
PETSC_EXTERN PetscErrorCode KSPQCGGetQuadratic(KSP, PetscReal *);
PETSC_EXTERN PetscErrorCode KSPQCGGetTrialStepNorm(KSP, PetscReal *);

PETSC_EXTERN PetscErrorCode KSPBCGSLSetXRes(KSP, PetscReal);
PETSC_EXTERN PetscErrorCode KSPBCGSLSetPol(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPBCGSLSetEll(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPBCGSLSetUsePseudoinverse(KSP, PetscBool);

PETSC_EXTERN PetscErrorCode KSPSetFromOptions(KSP);
PETSC_EXTERN PetscErrorCode KSPResetFromOptions(KSP);
PETSC_EXTERN PetscErrorCode KSPAddOptionsChecker(PetscErrorCode (*)(KSP));

PETSC_EXTERN PetscErrorCode KSPMonitorSetFromOptions(KSP, const char[], const char[], void *);
PETSC_EXTERN PetscErrorCode KSPMonitorLGCreate(MPI_Comm, const char[], const char[], const char[], PetscInt, const char *[], int, int, int, int, PetscDrawLG *);
PETSC_EXTERN PetscErrorCode KSPMonitorResidual(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorResidualDraw(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorResidualDrawLG(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorResidualDrawLGCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);
PETSC_EXTERN PetscErrorCode KSPMonitorResidualShort(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorResidualRange(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorTrueResidual(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorTrueResidualDraw(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorTrueResidualDrawLG(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorTrueResidualDrawLGCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);
PETSC_EXTERN PetscErrorCode KSPMonitorTrueResidualMax(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorError(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorErrorDraw(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorErrorDrawLG(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorErrorDrawLGCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);
PETSC_EXTERN PetscErrorCode KSPMonitorSolution(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorSolutionDraw(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorSolutionDrawLG(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorSolutionDrawLGCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);
PETSC_EXTERN PetscErrorCode KSPMonitorSingularValue(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPMonitorSingularValueCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);
PETSC_DEPRECATED_FUNCTION("Use KSPMonitorResidual() (since version 3.15)") static inline PetscErrorCode KSPMonitorDefault(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
{
  return KSPMonitorResidual(ksp, n, rnorm, vf);
}
PETSC_DEPRECATED_FUNCTION("Use KSPMonitorTrueResidual() (since version 3.15)") static inline PetscErrorCode KSPMonitorTrueResidualNorm(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
{
  return KSPMonitorTrueResidual(ksp, n, rnorm, vf);
}
PETSC_DEPRECATED_FUNCTION("Use KSPMonitorTrueResidualMax() (since version 3.15)") static inline PetscErrorCode KSPMonitorTrueResidualMaxNorm(KSP ksp, PetscInt n, PetscReal rnorm, PetscViewerAndFormat *vf)
{
  return KSPMonitorTrueResidualMax(ksp, n, rnorm, vf);
}

PETSC_EXTERN PetscErrorCode KSPGMRESMonitorKrylov(KSP, PetscInt, PetscReal, void *);
PETSC_EXTERN PetscErrorCode KSPMonitorDynamicTolerance(KSP, PetscInt, PetscReal, void *);
PETSC_EXTERN PetscErrorCode KSPMonitorDynamicToleranceDestroy(void **);
PETSC_EXTERN PetscErrorCode KSPMonitorDynamicToleranceCreate(void *);
PETSC_EXTERN PetscErrorCode KSPMonitorDynamicToleranceSetCoefficient(void *, PetscReal);
PETSC_EXTERN PetscErrorCode KSPMonitorSAWs(KSP, PetscInt, PetscReal, void *);
PETSC_EXTERN PetscErrorCode KSPMonitorSAWsCreate(KSP, void **);
PETSC_EXTERN PetscErrorCode KSPMonitorSAWsDestroy(void **);

PETSC_EXTERN PetscErrorCode KSPUnwindPreconditioner(KSP, Vec, Vec);
PETSC_EXTERN PetscErrorCode KSPInitialResidual(KSP, Vec, Vec, Vec, Vec, Vec);

PETSC_EXTERN PetscErrorCode KSPSetOperators(KSP, Mat, Mat);
PETSC_EXTERN PetscErrorCode KSPGetOperators(KSP, Mat *, Mat *);
PETSC_EXTERN PetscErrorCode KSPGetOperatorsSet(KSP, PetscBool *, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPSetOptionsPrefix(KSP, const char[]);
PETSC_EXTERN PetscErrorCode KSPAppendOptionsPrefix(KSP, const char[]);
PETSC_EXTERN PetscErrorCode KSPGetOptionsPrefix(KSP, const char *[]);

PETSC_EXTERN PetscErrorCode KSPSetDiagonalScale(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetDiagonalScale(KSP, PetscBool *);
PETSC_EXTERN PetscErrorCode KSPSetDiagonalScaleFix(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetDiagonalScaleFix(KSP, PetscBool *);

PETSC_EXTERN PetscErrorCode KSPView(KSP, PetscViewer);
PETSC_EXTERN PetscErrorCode KSPLoad(KSP, PetscViewer);
PETSC_EXTERN PetscErrorCode KSPViewFromOptions(KSP, PetscObject, const char[]);
PETSC_EXTERN PetscErrorCode KSPConvergedReasonView(KSP, PetscViewer);
PETSC_EXTERN PetscErrorCode KSPConvergedReasonViewSet(KSP, PetscErrorCode (*)(KSP, void *), void *vctx, PetscErrorCode (*)(void **));
PETSC_EXTERN PetscErrorCode KSPConvergedReasonViewFromOptions(KSP);
PETSC_EXTERN PetscErrorCode KSPConvergedReasonViewCancel(KSP);
PETSC_EXTERN PetscErrorCode KSPConvergedRateView(KSP, PetscViewer);

PETSC_DEPRECATED_FUNCTION("Use KSPConvergedReasonView() (since version 3.14)") static inline PetscErrorCode KSPReasonView(KSP ksp, PetscViewer v)
{
  return KSPConvergedReasonView(ksp, v);
}
PETSC_DEPRECATED_FUNCTION("Use KSPConvergedReasonViewFromOptions() (since version 3.14)") static inline PetscErrorCode KSPReasonViewFromOptions(KSP ksp)
{
  return KSPConvergedReasonViewFromOptions(ksp);
}

#define KSP_FILE_CLASSID 1211223

PETSC_EXTERN PetscErrorCode KSPLSQRSetExactMatNorm(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPLSQRSetComputeStandardErrorVec(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPLSQRGetStandardErrorVec(KSP, Vec *);
PETSC_EXTERN PetscErrorCode KSPLSQRGetNorms(KSP, PetscReal *, PetscReal *);
PETSC_EXTERN PetscErrorCode KSPLSQRMonitorResidual(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPLSQRMonitorResidualDrawLG(KSP, PetscInt, PetscReal, PetscViewerAndFormat *);
PETSC_EXTERN PetscErrorCode KSPLSQRMonitorResidualDrawLGCreate(PetscViewer, PetscViewerFormat, void *, PetscViewerAndFormat **);

PETSC_EXTERN PetscErrorCode PCRedundantGetKSP(PC, KSP *);
PETSC_EXTERN PetscErrorCode PCRedistributeGetKSP(PC, KSP *);
PETSC_EXTERN PetscErrorCode PCTelescopeGetKSP(PC, KSP *);

/*E
    KSPNormType - Norm calculated by the `KSP` and passed in the Krylov convergence
       test routines.

    Values:
+   `KSP_NORM_DEFAULT` - use the default for the current `KSPType`
.   `KSP_NORM_NONE` - use no norm calculation
.   `KSP_NORM_PRECONDITIONED` - use the preconditioned residual norm
.   `KSP_NORM_UNPRECONDITIONED` - use the unpreconditioned residual norm
-   `KSP_NORM_NATURAL` - use the natural norm (the norm induced by the linear operator)

   Level: advanced

   Note:
   Each solver only supports a subset of these and some may support different ones
   depending on left or right preconditioning, see `KSPSetPCSide()`

   Developer Note:
   This must match the values in petsc/finclude/petscksp.h

.seealso: [](chapter_ksp), `KSP`, `PCSide`, `KSPSolve()`, `KSPGetConvergedReason()`, `KSPSetNormType()`,
          `KSPSetConvergenceTest()`, `KSPSetPCSide()`
E*/
typedef enum {
  KSP_NORM_DEFAULT          = -1,
  KSP_NORM_NONE             = 0,
  KSP_NORM_PRECONDITIONED   = 1,
  KSP_NORM_UNPRECONDITIONED = 2,
  KSP_NORM_NATURAL          = 3
} KSPNormType;
#define KSP_NORM_MAX (KSP_NORM_NATURAL + 1)
PETSC_EXTERN const char *const *const KSPNormTypes;

/*MC
    KSP_NORM_NONE - Do not compute a norm during the Krylov process. This will
          possibly save some computation but means the convergence test cannot
          be based on a norm of a residual etc.

   Level: advanced

    Note:
    Some Krylov methods need to compute a residual norm (such as `KPSGMRES`) and then this option is ignored

.seealso: [](chapter_ksp), `KSPNormType`, `KSP`, `KSPSetNormType()`, `KSP_NORM_PRECONDITIONED`, `KSP_NORM_UNPRECONDITIONED`, `KSP_NORM_NATURAL`
M*/

/*MC
    KSP_NORM_PRECONDITIONED - Compute the norm of the preconditioned residual B*(b - A*x), if left preconditioning, and pass that to the
       convergence test routine.

   Level: advanced

.seealso: [](chapter_ksp), `KSPNormType`, `KSP`, `KSPSetNormType()`, `KSP_NORM_NONE`, `KSP_NORM_UNPRECONDITIONED`, `KSP_NORM_NATURAL`, `KSPSetConvergenceTest()`
M*/

/*MC
    KSP_NORM_UNPRECONDITIONED - Compute the norm of the true residual (b - A*x) and pass that to the
       convergence test routine.

   Level: advanced

.seealso: [](chapter_ksp), `KSPNormType`, `KSP`, `KSPSetNormType()`, `KSP_NORM_NONE`, `KSP_NORM_PRECONDITIONED`, `KSP_NORM_NATURAL`, `KSPSetConvergenceTest()`
M*/

/*MC
    KSP_NORM_NATURAL - Compute the 'natural norm' of residual sqrt((b - A*x)*B*(b - A*x)) and pass that to the
       convergence test routine. This is only supported by  `KSPCG`, `KSPCR`, `KSPCGNE`, `KSPCGS`, `KSPFCG`, `KSPPIPEFCG`, `KSPPIPEGCR`

   Level: advanced

.seealso: [](chapter_ksp), `KSPNormType`, `KSP`, `KSPSetNormType()`, `KSP_NORM_NONE`, `KSP_NORM_PRECONDITIONED`, `KSP_NORM_UNPRECONDITIONED`, `KSPSetConvergenceTest()`
M*/

PETSC_EXTERN PetscErrorCode KSPSetNormType(KSP, KSPNormType);
PETSC_EXTERN PetscErrorCode KSPGetNormType(KSP, KSPNormType *);
PETSC_EXTERN PetscErrorCode KSPSetSupportedNorm(KSP ksp, KSPNormType, PCSide, PetscInt);
PETSC_EXTERN PetscErrorCode KSPSetCheckNormIteration(KSP, PetscInt);
PETSC_EXTERN PetscErrorCode KSPSetLagNorm(KSP, PetscBool);

#define KSP_DIVERGED_PCSETUP_FAILED_DEPRECATED KSP_DIVERGED_PCSETUP_FAILED PETSC_DEPRECATED_ENUM("Use KSP_DIVERGED_PC_FAILED (since version 3.11)")
/*E
    KSPConvergedReason - reason a Krylov method was determined to have converged or diverged

   Level: beginner

   Values:
+  `KSP_CONVERGED_RTOL_NORMAL` - requested decrease in the residual for the normal equations
.  `KSP_CONVERGED_ATOL_NORMAL` - requested absolute value in the residual for the normal equations
.  `KSP_CONVERGED_RTOL` - requested decrease in the residual
.  `KSP_CONVERGED_ATOL` - requested absolute value in the residual
.  `KSP_CONVERGED_ITS` - requested number of iterations
.  `KSP_CONVERGED_CG_NEG_CURVE` - see note below
.  `KSP_CONVERGED_CG_CONSTRAINED` - see note below
.  `KSP_CONVERGED_STEP_LENGTH` - see note below
.  `KSP_CONVERGED_HAPPY_BREAKDOWN` - happy breakdown (meaning early convergence of the `KSPType` occurred.
.  `KSP_DIVERGED_NULL` - breakdown when solving the Hessenberg system within GMRES
.  `KSP_DIVERGED_ITS` - requested number of iterations
.  `KSP_DIVERGED_DTOL` - large increase in the residual norm
.  `KSP_DIVERGED_BREAKDOWN` - breakdown in the Krylov method
.  `KSP_DIVERGED_BREAKDOWN_BICG` - breakdown in the `KSPBGCS` Krylov method
.  `KSP_DIVERGED_NONSYMMETRIC` - the operator or preonditioner was not symmetric for a `KSPType` that requires symmetry
.  `KSP_DIVERGED_INDEFINITE_PC` - the preconditioner was indefinite for a `KSPType` that requires it be definite
.  `KSP_DIVERGED_NANORINF` - a not a number of infinity was detected in a vector during the computation
.  `KSP_DIVERGED_INDEFINITE_MAT` - the operator was indefinite for a `KSPType` that requires it be definite
-  `KSP_DIVERGED_PC_FAILED` - the action of the preconditioner failed for some reason

   Note:
   The values  `KSP_CONVERGED_CG_NEG_CURVE`, `KSP_CONVERGED_CG_CONSTRAINED`, and `KSP_CONVERGED_STEP_LENGTH` are returned only by the special `KSPNASH`,
   `KSPSTCG`, and `KSPGLTR` solvers which are used by the `SNESNEWTONTR` (trust region) solver.

   Developer Notes:
   This must match the values in petsc/finclude/petscksp.h

   The string versions of these are `KSPConvergedReasons`; if you change
   any of the values here also change them that array of names.

.seealso: [](chapter_ksp), `KSP`, `KSPSolve()`, `KSPGetConvergedReason()`, `KSPSetTolerances()`, `KSPConvergedReasonView()`
E*/
typedef enum { /* converged */
  KSP_CONVERGED_RTOL_NORMAL     = 1,
  KSP_CONVERGED_ATOL_NORMAL     = 9,
  KSP_CONVERGED_RTOL            = 2,
  KSP_CONVERGED_ATOL            = 3,
  KSP_CONVERGED_ITS             = 4,
  KSP_CONVERGED_CG_NEG_CURVE    = 5,
  KSP_CONVERGED_CG_CONSTRAINED  = 6,
  KSP_CONVERGED_STEP_LENGTH     = 7,
  KSP_CONVERGED_HAPPY_BREAKDOWN = 8,
  /* diverged */
  KSP_DIVERGED_NULL                      = -2,
  KSP_DIVERGED_ITS                       = -3,
  KSP_DIVERGED_DTOL                      = -4,
  KSP_DIVERGED_BREAKDOWN                 = -5,
  KSP_DIVERGED_BREAKDOWN_BICG            = -6,
  KSP_DIVERGED_NONSYMMETRIC              = -7,
  KSP_DIVERGED_INDEFINITE_PC             = -8,
  KSP_DIVERGED_NANORINF                  = -9,
  KSP_DIVERGED_INDEFINITE_MAT            = -10,
  KSP_DIVERGED_PC_FAILED                 = -11,
  KSP_DIVERGED_PCSETUP_FAILED_DEPRECATED = -11,

  KSP_CONVERGED_ITERATING = 0
} KSPConvergedReason;
PETSC_EXTERN const char *const *KSPConvergedReasons;

/*MC
     KSP_CONVERGED_RTOL - norm(r) <= rtol*norm(b) or rtol*norm(b - A*x_0) if `KSPConvergedDefaultSetUIRNorm()` was called

   Level: beginner

   See `KSPNormType` and `KSPSetNormType()` for possible norms that may be used. By default
   for left preconditioning it is the 2-norm of the preconditioned residual, and the
   2-norm of the residual for right preconditioning

   See also `KSP_CONVERGED_ATOL` which may apply before this tolerance.

.seealso: [](chapter_ksp), `KSPNormType`, `KSP_CONVERGED_ATOL`, `KSP_DIVERGED_DTOL`, `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_CONVERGED_ATOL - norm(r) <= atol

   Level: beginner

   See `KSPNormType` and `KSPSetNormType()` for possible norms that may be used. By default
       for left preconditioning it is the 2-norm of the preconditioned residual, and the
       2-norm of the residual for right preconditioning

   See also `KSP_CONVERGED_RTOL` which may apply before this tolerance.

.seealso: [](chapter_ksp), `KSPNormType`, `KSP_CONVERGED_RTOL`, `KSP_DIVERGED_DTOL`, `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_DTOL - norm(r) >= dtol*norm(b)

   Level: beginner

   See `KSPNormType` and `KSPSetNormType()` for possible norms that may be used. By default
       for left preconditioning it is the 2-norm of the preconditioned residual, and the
       2-norm of the residual for right preconditioning

   Level: beginner

.seealso: [](chapter_ksp), `KSPNormType`, `KSP_CONVERGED_ATOL`, `KSP_DIVERGED_RTOL`, `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_ITS - Ran out of iterations before any convergence criteria was
      reached

   Level: beginner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_CONVERGED_ITS - Used by the `KSPPREONLY` solver after the single iteration of
           the preconditioner is applied. Also used when the `KSPConvergedSkip()` convergence
           test routine is set in KSP.

   Level: beginner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_BREAKDOWN - A breakdown in the Krylov method was detected so the
          method could not continue to enlarge the Krylov space. Could be due to a singular matrix or
          preconditioner. In `KSPHPDDM`, this is also returned when some search directions within a block
          are colinear.

   Level: beginner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_BREAKDOWN_BICG - A breakdown in the `KSPBICG` method was detected so the
          method could not continue to enlarge the Krylov space.

   Level: beginner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_NONSYMMETRIC - It appears the operator or preconditioner is not
        symmetric and this Krylov method (`KSPCG`, `KSPMINRES`, `KSPCR`) requires symmetry

   Level: beginner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_INDEFINITE_PC - It appears the preconditioner is indefinite (has both
        positive and negative eigenvalues) and this Krylov method (`KSPCG`) requires it to
        be positive definite

   Level: beginner

     Note:
    This can happen with the `PCICC` preconditioner, use the options database option `-pc_factor_shift_positive_definite` to force
  the `PCICC` preconditioner to generate a positive definite preconditioner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_DIVERGED_PC_FAILED - It was not possible to build or use the requested preconditioner. This is usually due to a
     zero pivot in a factorization. It can also result from a failure in a subpreconditioner inside a nested preconditioner
     such as `PCFIELDSPLIT`.

   Level: beginner

    Note:
    Run with `-ksp_error_if_not_converged` to stop the program when the error is detected and print an error message with details.

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

/*MC
     KSP_CONVERGED_ITERATING - This flag is returned if `KSPGetConvergedReason()` is called
        while `KSPSolve()` is still running.

   Level: beginner

.seealso: [](chapter_ksp), `KSPSolve()`, `KSPGetConvergedReason()`, `KSPConvergedReason`, `KSPSetTolerances()`

M*/

PETSC_EXTERN PetscErrorCode KSPSetConvergenceTest(KSP, PetscErrorCode (*)(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *), void *, PetscErrorCode (*)(void *));
PETSC_EXTERN PetscErrorCode KSPGetConvergenceTest(KSP, PetscErrorCode (**)(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *), void **, PetscErrorCode (**)(void *));
PETSC_EXTERN PetscErrorCode KSPGetAndClearConvergenceTest(KSP, PetscErrorCode (**)(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *), void **, PetscErrorCode (**)(void *));
PETSC_EXTERN PetscErrorCode KSPGetConvergenceContext(KSP, void *);
PETSC_EXTERN PetscErrorCode KSPConvergedDefault(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *);
PETSC_EXTERN PetscErrorCode KSPLSQRConvergedDefault(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *);
PETSC_EXTERN PetscErrorCode KSPConvergedDefaultDestroy(void *);
PETSC_EXTERN PetscErrorCode KSPConvergedDefaultCreate(void **);
PETSC_EXTERN PetscErrorCode KSPConvergedDefaultSetUIRNorm(KSP);
PETSC_EXTERN PetscErrorCode KSPConvergedDefaultSetUMIRNorm(KSP);
PETSC_EXTERN PetscErrorCode KSPConvergedDefaultSetConvergedMaxits(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPConvergedSkip(KSP, PetscInt, PetscReal, KSPConvergedReason *, void *);
PETSC_EXTERN PetscErrorCode KSPGetConvergedReason(KSP, KSPConvergedReason *);
PETSC_EXTERN PetscErrorCode KSPGetConvergedReasonString(KSP, const char **);
PETSC_EXTERN PetscErrorCode KSPComputeConvergenceRate(KSP, PetscReal *, PetscReal *, PetscReal *, PetscReal *);

PETSC_DEPRECATED_FUNCTION("Use KSPConvergedDefault() (since version 3.5)") static inline void KSPDefaultConverged(void)
{ /* never called */
}
#define KSPDefaultConverged (KSPDefaultConverged, KSPConvergedDefault)
PETSC_DEPRECATED_FUNCTION("Use KSPConvergedDefaultDestroy() (since version 3.5)") static inline void KSPDefaultConvergedDestroy(void)
{ /* never called */
}
#define KSPDefaultConvergedDestroy (KSPDefaultConvergedDestroy, KSPConvergedDefaultDestroy)
PETSC_DEPRECATED_FUNCTION("Use KSPConvergedDefaultCreate() (since version 3.5)") static inline void KSPDefaultConvergedCreate(void)
{ /* never called */
}
#define KSPDefaultConvergedCreate (KSPDefaultConvergedCreate, KSPConvergedDefaultCreate)
PETSC_DEPRECATED_FUNCTION("Use KSPConvergedDefaultSetUIRNorm() (since version 3.5)") static inline void KSPDefaultConvergedSetUIRNorm(void)
{ /* never called */
}
#define KSPDefaultConvergedSetUIRNorm (KSPDefaultConvergedSetUIRNorm, KSPConvergedDefaultSetUIRNorm)
PETSC_DEPRECATED_FUNCTION("Use KSPConvergedDefaultSetUMIRNorm() (since version 3.5)") static inline void KSPDefaultConvergedSetUMIRNorm(void)
{ /* never called */
}
#define KSPDefaultConvergedSetUMIRNorm (KSPDefaultConvergedSetUMIRNorm, KSPConvergedDefaultSetUMIRNorm)
PETSC_DEPRECATED_FUNCTION("Use KSPConvergedSkip() (since version 3.5)") static inline void KSPSkipConverged(void)
{ /* never called */
}
#define KSPSkipConverged (KSPSkipConverged, KSPConvergedSkip)

PETSC_EXTERN PetscErrorCode KSPComputeOperator(KSP, MatType, Mat *);
PETSC_DEPRECATED_FUNCTION("Use KSPComputeOperator() (since version 3.12)") static inline PetscErrorCode KSPComputeExplicitOperator(KSP A, Mat *B)
{
  return KSPComputeOperator(A, NULL, B);
}

/*E
    KSPCGType - Determines what type of `KSPCG` to use

   Level: beginner

   Values:
 + `KSP_CG_SYMMETRIC` - the matrix is complex symmetric
 - `KSP_CG_HERMITIAN` - the matrix is complex Hermitian

.seealso: [](chapter_ksp), `KSP`, `KSPCGSetType()`
E*/
typedef enum {
  KSP_CG_SYMMETRIC = 0,
  KSP_CG_HERMITIAN = 1
} KSPCGType;
PETSC_EXTERN const char *const KSPCGTypes[];

PETSC_EXTERN PetscErrorCode KSPCGSetType(KSP, KSPCGType);
PETSC_EXTERN PetscErrorCode KSPCGUseSingleReduction(KSP, PetscBool);

PETSC_EXTERN PetscErrorCode KSPCGSetRadius(KSP, PetscReal);
PETSC_EXTERN PetscErrorCode KSPCGGetNormD(KSP, PetscReal *);
PETSC_EXTERN PetscErrorCode KSPCGGetObjFcn(KSP, PetscReal *);

PETSC_EXTERN PetscErrorCode KSPGLTRGetMinEig(KSP, PetscReal *);
PETSC_EXTERN PetscErrorCode KSPGLTRGetLambda(KSP, PetscReal *);
PETSC_DEPRECATED_FUNCTION("Use KSPGLTRGetMinEig (since v3.12)") static inline PetscErrorCode KSPCGGLTRGetMinEig(KSP ksp, PetscReal *x)
{
  return KSPGLTRGetMinEig(ksp, x);
}
PETSC_DEPRECATED_FUNCTION("Use KSPGLTRGetLambda (since v3.12)") static inline PetscErrorCode KSPCGGLTRGetLambda(KSP ksp, PetscReal *x)
{
  return KSPGLTRGetLambda(ksp, x);
}

PETSC_EXTERN PetscErrorCode KSPPythonSetType(KSP, const char[]);
PETSC_EXTERN PetscErrorCode KSPPythonGetType(KSP, const char *[]);

PETSC_EXTERN PetscErrorCode PCSetPreSolve(PC, PetscErrorCode (*)(PC, KSP));
PETSC_EXTERN PetscErrorCode PCPreSolve(PC, KSP);
PETSC_EXTERN PetscErrorCode PCPostSolve(PC, KSP);

#include <petscdrawtypes.h>
PETSC_EXTERN PetscErrorCode KSPMonitorLGRange(KSP, PetscInt, PetscReal, void *);

PETSC_EXTERN PetscErrorCode PCShellSetPreSolve(PC, PetscErrorCode (*)(PC, KSP, Vec, Vec));
PETSC_EXTERN PetscErrorCode PCShellSetPostSolve(PC, PetscErrorCode (*)(PC, KSP, Vec, Vec));

/*S
     KSPGuess - Abstract PETSc object that manages all initial guess generation methods for Krylov methods.

   Level: intermediate

.seealso: [](chapter_ksp), `KSPCreate()`, `KSPSetGuessType()`, `KSPGuessType`
S*/
typedef struct _p_KSPGuess *KSPGuess;
/*J
    KSPGuessType - String with the name of a PETSc initial guess approach for Krylov methods.

   Level: intermediate

   Values:
 + `KSPGUESSFISCHER` - methodology developed by Paul Fischer
 - `KSPGUESSPOD` - methodology based on proper orthogonal decomposition

.seealso: [](chapter_ksp), `KSP`, `KSPGuess`
J*/
typedef const char *KSPGuessType;
#define KSPGUESSFISCHER "fischer"
#define KSPGUESSPOD     "pod"

PETSC_EXTERN PetscErrorCode KSPGuessRegister(const char[], PetscErrorCode (*)(KSPGuess));
PETSC_EXTERN PetscErrorCode KSPSetGuess(KSP, KSPGuess);
PETSC_EXTERN PetscErrorCode KSPGetGuess(KSP, KSPGuess *);
PETSC_EXTERN PetscErrorCode KSPGuessView(KSPGuess, PetscViewer);
PETSC_EXTERN PetscErrorCode KSPGuessDestroy(KSPGuess *);
PETSC_EXTERN PetscErrorCode KSPGuessCreate(MPI_Comm, KSPGuess *);
PETSC_EXTERN PetscErrorCode KSPGuessSetType(KSPGuess, KSPGuessType);
PETSC_EXTERN PetscErrorCode KSPGuessGetType(KSPGuess, KSPGuessType *);
PETSC_EXTERN PetscErrorCode KSPGuessSetTolerance(KSPGuess, PetscReal);
PETSC_EXTERN PetscErrorCode KSPGuessSetUp(KSPGuess);
PETSC_EXTERN PetscErrorCode KSPGuessUpdate(KSPGuess, Vec, Vec);
PETSC_EXTERN PetscErrorCode KSPGuessFormGuess(KSPGuess, Vec, Vec);
PETSC_EXTERN PetscErrorCode KSPGuessSetFromOptions(KSPGuess);
PETSC_EXTERN PetscErrorCode KSPGuessFischerSetModel(KSPGuess, PetscInt, PetscInt);
PETSC_EXTERN PetscErrorCode KSPSetUseFischerGuess(KSP, PetscInt, PetscInt);
PETSC_EXTERN PetscErrorCode KSPSetInitialGuessKnoll(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetInitialGuessKnoll(KSP, PetscBool *);

/*E
    MatSchurComplementAinvType - Determines how to approximate the inverse of the (0,0) block in Schur complement preconditioning matrix assembly routines

    Level: intermediate

.seealso: `MatSchurComplementGetAinvType()`, `MatSchurComplementSetAinvType()`, `MatSchurComplementGetPmat()`, `MatGetSchurComplement()`,
          `MatCreateSchurComplementPmat()`
E*/
typedef enum {
  MAT_SCHUR_COMPLEMENT_AINV_DIAG,
  MAT_SCHUR_COMPLEMENT_AINV_LUMP,
  MAT_SCHUR_COMPLEMENT_AINV_BLOCK_DIAG,
  MAT_SCHUR_COMPLEMENT_AINV_FULL
} MatSchurComplementAinvType;
PETSC_EXTERN const char *const MatSchurComplementAinvTypes[];

typedef enum {
  MAT_LMVM_SYMBROYDEN_SCALE_NONE     = 0,
  MAT_LMVM_SYMBROYDEN_SCALE_SCALAR   = 1,
  MAT_LMVM_SYMBROYDEN_SCALE_DIAGONAL = 2,
  MAT_LMVM_SYMBROYDEN_SCALE_USER     = 3
} MatLMVMSymBroydenScaleType;
PETSC_EXTERN const char *const MatLMVMSymBroydenScaleTypes[];

PETSC_EXTERN PetscErrorCode MatCreateSchurComplement(Mat, Mat, Mat, Mat, Mat, Mat *);
PETSC_EXTERN PetscErrorCode MatSchurComplementGetKSP(Mat, KSP *);
PETSC_EXTERN PetscErrorCode MatSchurComplementSetKSP(Mat, KSP);
PETSC_EXTERN PetscErrorCode MatSchurComplementSetSubMatrices(Mat, Mat, Mat, Mat, Mat, Mat);
PETSC_EXTERN PetscErrorCode MatSchurComplementUpdateSubMatrices(Mat, Mat, Mat, Mat, Mat, Mat);
PETSC_EXTERN PetscErrorCode MatSchurComplementGetSubMatrices(Mat, Mat *, Mat *, Mat *, Mat *, Mat *);
PETSC_EXTERN PetscErrorCode MatSchurComplementSetAinvType(Mat, MatSchurComplementAinvType);
PETSC_EXTERN PetscErrorCode MatSchurComplementGetAinvType(Mat, MatSchurComplementAinvType *);
PETSC_EXTERN PetscErrorCode MatSchurComplementGetPmat(Mat, MatReuse, Mat *);
PETSC_EXTERN PetscErrorCode MatSchurComplementComputeExplicitOperator(Mat, Mat *);
PETSC_EXTERN PetscErrorCode MatGetSchurComplement(Mat, IS, IS, IS, IS, MatReuse, Mat *, MatSchurComplementAinvType, MatReuse, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateSchurComplementPmat(Mat, Mat, Mat, Mat, MatSchurComplementAinvType, MatReuse, Mat *);

PETSC_EXTERN PetscErrorCode MatCreateLMVMDFP(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMBFGS(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMSR1(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMBroyden(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMBadBroyden(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMSymBroyden(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMSymBadBroyden(MPI_Comm, PetscInt, PetscInt, Mat *);
PETSC_EXTERN PetscErrorCode MatCreateLMVMDiagBroyden(MPI_Comm, PetscInt, PetscInt, Mat *);

PETSC_EXTERN PetscErrorCode MatLMVMUpdate(Mat, Vec, Vec);
PETSC_EXTERN PetscErrorCode MatLMVMIsAllocated(Mat, PetscBool *);
PETSC_EXTERN PetscErrorCode MatLMVMAllocate(Mat, Vec, Vec);
PETSC_EXTERN PetscErrorCode MatLMVMReset(Mat, PetscBool);
PETSC_EXTERN PetscErrorCode MatLMVMResetShift(Mat);
PETSC_EXTERN PetscErrorCode MatLMVMClearJ0(Mat);
PETSC_EXTERN PetscErrorCode MatLMVMSetJ0(Mat, Mat);
PETSC_EXTERN PetscErrorCode MatLMVMSetJ0Scale(Mat, PetscReal);
PETSC_EXTERN PetscErrorCode MatLMVMSetJ0Diag(Mat, Vec);
PETSC_EXTERN PetscErrorCode MatLMVMSetJ0PC(Mat, PC);
PETSC_EXTERN PetscErrorCode MatLMVMSetJ0KSP(Mat, KSP);
PETSC_EXTERN PetscErrorCode MatLMVMApplyJ0Fwd(Mat, Vec, Vec);
PETSC_EXTERN PetscErrorCode MatLMVMApplyJ0Inv(Mat, Vec, Vec);
PETSC_EXTERN PetscErrorCode MatLMVMGetJ0(Mat, Mat *);
PETSC_EXTERN PetscErrorCode MatLMVMGetJ0PC(Mat, PC *);
PETSC_EXTERN PetscErrorCode MatLMVMGetJ0KSP(Mat, KSP *);
PETSC_EXTERN PetscErrorCode MatLMVMSetHistorySize(Mat, PetscInt);
PETSC_EXTERN PetscErrorCode MatLMVMGetUpdateCount(Mat, PetscInt *);
PETSC_EXTERN PetscErrorCode MatLMVMGetRejectCount(Mat, PetscInt *);
PETSC_EXTERN PetscErrorCode MatLMVMSymBroydenSetDelta(Mat, PetscScalar);
PETSC_EXTERN PetscErrorCode MatLMVMSymBroydenSetScaleType(Mat, MatLMVMSymBroydenScaleType);

PETSC_EXTERN PetscErrorCode KSPSetDM(KSP, DM);
PETSC_EXTERN PetscErrorCode KSPSetDMActive(KSP, PetscBool);
PETSC_EXTERN PetscErrorCode KSPGetDM(KSP, DM *);
PETSC_EXTERN PetscErrorCode KSPSetApplicationContext(KSP, void *);
PETSC_EXTERN PetscErrorCode KSPGetApplicationContext(KSP, void *);
PETSC_EXTERN PetscErrorCode KSPSetComputeRHS(KSP, PetscErrorCode (*func)(KSP, Vec, void *), void *);
PETSC_EXTERN PetscErrorCode KSPSetComputeOperators(KSP, PetscErrorCode (*)(KSP, Mat, Mat, void *), void *);
PETSC_EXTERN PetscErrorCode KSPSetComputeInitialGuess(KSP, PetscErrorCode (*)(KSP, Vec, void *), void *);
PETSC_EXTERN PetscErrorCode DMKSPSetComputeOperators(DM, PetscErrorCode (*)(KSP, Mat, Mat, void *), void *);
PETSC_EXTERN PetscErrorCode DMKSPGetComputeOperators(DM, PetscErrorCode (**)(KSP, Mat, Mat, void *), void *);
PETSC_EXTERN PetscErrorCode DMKSPSetComputeRHS(DM, PetscErrorCode (*)(KSP, Vec, void *), void *);
PETSC_EXTERN PetscErrorCode DMKSPGetComputeRHS(DM, PetscErrorCode (**)(KSP, Vec, void *), void *);
PETSC_EXTERN PetscErrorCode DMKSPSetComputeInitialGuess(DM, PetscErrorCode (*)(KSP, Vec, void *), void *);
PETSC_EXTERN PetscErrorCode DMKSPGetComputeInitialGuess(DM, PetscErrorCode (**)(KSP, Vec, void *), void *);

PETSC_EXTERN PetscErrorCode DMGlobalToLocalSolve(DM, Vec, Vec);
PETSC_EXTERN PetscErrorCode DMProjectField(DM, PetscReal, Vec, void (**)(PetscInt, PetscInt, PetscInt, const PetscInt[], const PetscInt[], const PetscScalar[], const PetscScalar[], const PetscScalar[], const PetscInt[], const PetscInt[], const PetscScalar[], const PetscScalar[], const PetscScalar[], PetscReal, const PetscReal[], PetscInt, const PetscScalar[], PetscScalar[]), InsertMode, Vec);

PETSC_EXTERN PetscErrorCode DMAdaptInterpolator(DM, DM, Mat, KSP, Mat, Mat, Mat *, void *);
PETSC_EXTERN PetscErrorCode DMCheckInterpolator(DM, Mat, Mat, Mat, PetscReal);
#endif