snes/utils/dmsnes.c

#include <petsc/private/snesimpl.h> /*I "petscsnes.h" I*/
#include <petsc/private/dmimpl.h>   /*I "petscdm.h" I*/

static PetscErrorCode DMSNESUnsetFunctionContext_DMSNES(DMSNES sdm) {
  PetscFunctionBegin;
  PetscCall(PetscObjectCompose((PetscObject)sdm, "function ctx", NULL));
  sdm->functionctxcontainer = NULL;
  PetscFunctionReturn(0);
}

static PetscErrorCode DMSNESUnsetJacobianContext_DMSNES(DMSNES sdm) {
  PetscFunctionBegin;
  PetscCall(PetscObjectCompose((PetscObject)sdm, "jacobian ctx", NULL));
  sdm->jacobianctxcontainer = NULL;
  PetscFunctionReturn(0);
}

static PetscErrorCode DMSNESDestroy(DMSNES *kdm) {
  PetscFunctionBegin;
  if (!*kdm) PetscFunctionReturn(0);
  PetscValidHeaderSpecific((*kdm), DMSNES_CLASSID, 1);
  if (--((PetscObject)(*kdm))->refct > 0) {
    *kdm = NULL;
    PetscFunctionReturn(0);
  }
  PetscCall(DMSNESUnsetFunctionContext_DMSNES(*kdm));
  PetscCall(DMSNESUnsetJacobianContext_DMSNES(*kdm));
  if ((*kdm)->ops->destroy) PetscCall(((*kdm)->ops->destroy)(*kdm));
  PetscCall(PetscHeaderDestroy(kdm));
  PetscFunctionReturn(0);
}

PetscErrorCode DMSNESLoad(DMSNES kdm, PetscViewer viewer) {
  PetscFunctionBegin;
  PetscCall(PetscViewerBinaryRead(viewer, &kdm->ops->computefunction, 1, NULL, PETSC_FUNCTION));
  PetscCall(PetscViewerBinaryRead(viewer, &kdm->ops->computejacobian, 1, NULL, PETSC_FUNCTION));
  PetscFunctionReturn(0);
}

PetscErrorCode DMSNESView(DMSNES kdm, PetscViewer viewer) {
  PetscBool isascii, isbinary;

  PetscFunctionBegin;
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
  if (isascii) {
#if defined(PETSC_SERIALIZE_FUNCTIONS) && defined(PETSC_SERIALIZE_FUNCTIONS_VIEW)
    const char *fname;

    PetscCall(PetscFPTFind(kdm->ops->computefunction, &fname));
    if (fname) { PetscCall(PetscViewerASCIIPrintf(viewer, "Function used by SNES: %s\n", fname)); }
    PetscCall(PetscFPTFind(kdm->ops->computejacobian, &fname));
    if (fname) { PetscCall(PetscViewerASCIIPrintf(viewer, "Jacobian function used by SNES: %s\n", fname)); }
#endif
  } else if (isbinary) {
    struct {
      PetscErrorCode (*func)(SNES, Vec, Vec, void *);
    } funcstruct;
    struct {
      PetscErrorCode (*jac)(SNES, Vec, Mat, Mat, void *);
    } jacstruct;
    funcstruct.func = kdm->ops->computefunction;
    jacstruct.jac   = kdm->ops->computejacobian;
    PetscCall(PetscViewerBinaryWrite(viewer, &funcstruct, 1, PETSC_FUNCTION));
    PetscCall(PetscViewerBinaryWrite(viewer, &jacstruct, 1, PETSC_FUNCTION));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMSNESCreate(MPI_Comm comm, DMSNES *kdm) {
  PetscFunctionBegin;
  PetscCall(SNESInitializePackage());
  PetscCall(PetscHeaderCreate(*kdm, DMSNES_CLASSID, "DMSNES", "DMSNES", "DMSNES", comm, DMSNESDestroy, DMSNESView));
  PetscFunctionReturn(0);
}

/* Attaches the DMSNES to the coarse level.
 * Under what conditions should we copy versus duplicate?
 */
static PetscErrorCode DMCoarsenHook_DMSNES(DM dm, DM dmc, void *ctx) {
  PetscFunctionBegin;
  PetscCall(DMCopyDMSNES(dm, dmc));
  PetscFunctionReturn(0);
}

/* This could restrict auxiliary information to the coarse level.
 */
static PetscErrorCode DMRestrictHook_DMSNES(DM dm, Mat Restrict, Vec rscale, Mat Inject, DM dmc, void *ctx) {
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

/* Attaches the DMSNES to the subdomain. */
static PetscErrorCode DMSubDomainHook_DMSNES(DM dm, DM subdm, void *ctx) {
  PetscFunctionBegin;
  PetscCall(DMCopyDMSNES(dm, subdm));
  PetscFunctionReturn(0);
}

/* This could restrict auxiliary information to the coarse level.
 */
static PetscErrorCode DMSubDomainRestrictHook_DMSNES(DM dm, VecScatter gscat, VecScatter lscat, DM subdm, void *ctx) {
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

static PetscErrorCode DMRefineHook_DMSNES(DM dm, DM dmf, void *ctx) {
  PetscFunctionBegin;
  PetscCall(DMCopyDMSNES(dm, dmf));
  PetscFunctionReturn(0);
}

/* This could restrict auxiliary information to the coarse level.
 */
static PetscErrorCode DMInterpolateHook_DMSNES(DM dm, Mat Interp, DM dmf, void *ctx) {
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESCopy - copies the information in a DMSNES to another DMSNES

   Not Collective

   Input Parameters:
+  kdm - Original DMSNES
-  nkdm - DMSNES to receive the data, should have been created with DMSNESCreate()

   Level: developer

.seealso: `DMSNESCreate()`, `DMSNESDestroy()`
@*/
PetscErrorCode DMSNESCopy(DMSNES kdm, DMSNES nkdm) {
  PetscFunctionBegin;
  PetscValidHeaderSpecific(kdm, DMSNES_CLASSID, 1);
  PetscValidHeaderSpecific(nkdm, DMSNES_CLASSID, 2);
  nkdm->ops->computefunction  = kdm->ops->computefunction;
  nkdm->ops->computejacobian  = kdm->ops->computejacobian;
  nkdm->ops->computegs        = kdm->ops->computegs;
  nkdm->ops->computeobjective = kdm->ops->computeobjective;
  nkdm->ops->computepjacobian = kdm->ops->computepjacobian;
  nkdm->ops->computepfunction = kdm->ops->computepfunction;
  nkdm->ops->destroy          = kdm->ops->destroy;
  nkdm->ops->duplicate        = kdm->ops->duplicate;

  nkdm->gsctx                = kdm->gsctx;
  nkdm->pctx                 = kdm->pctx;
  nkdm->objectivectx         = kdm->objectivectx;
  nkdm->originaldm           = kdm->originaldm;
  nkdm->functionctxcontainer = kdm->functionctxcontainer;
  nkdm->jacobianctxcontainer = kdm->jacobianctxcontainer;
  if (nkdm->functionctxcontainer) PetscCall(PetscObjectCompose((PetscObject)nkdm, "function ctx", (PetscObject)nkdm->functionctxcontainer));
  if (nkdm->jacobianctxcontainer) PetscCall(PetscObjectCompose((PetscObject)nkdm, "jacobian ctx", (PetscObject)nkdm->jacobianctxcontainer));

  /*
  nkdm->fortran_func_pointers[0] = kdm->fortran_func_pointers[0];
  nkdm->fortran_func_pointers[1] = kdm->fortran_func_pointers[1];
  nkdm->fortran_func_pointers[2] = kdm->fortran_func_pointers[2];
  */

  /* implementation specific copy hooks */
  PetscTryTypeMethod(kdm, duplicate, nkdm);
  PetscFunctionReturn(0);
}

/*@C
   DMGetDMSNES - get read-only private DMSNES context from a DM

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameter:
.  snesdm - private DMSNES context

   Level: developer

   Notes:
   Use DMGetDMSNESWrite() if write access is needed. The DMSNESSetXXX API should be used wherever possible.

.seealso: `DMGetDMSNESWrite()`
@*/
PetscErrorCode DMGetDMSNES(DM dm, DMSNES *snesdm) {
  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  *snesdm = (DMSNES)dm->dmsnes;
  if (!*snesdm) {
    PetscCall(PetscInfo(dm, "Creating new DMSNES\n"));
    PetscCall(DMSNESCreate(PetscObjectComm((PetscObject)dm), snesdm));

    dm->dmsnes            = (PetscObject)*snesdm;
    (*snesdm)->originaldm = dm;
    PetscCall(DMCoarsenHookAdd(dm, DMCoarsenHook_DMSNES, DMRestrictHook_DMSNES, NULL));
    PetscCall(DMRefineHookAdd(dm, DMRefineHook_DMSNES, DMInterpolateHook_DMSNES, NULL));
    PetscCall(DMSubDomainHookAdd(dm, DMSubDomainHook_DMSNES, DMSubDomainRestrictHook_DMSNES, NULL));
  }
  PetscFunctionReturn(0);
}

/*@C
   DMGetDMSNESWrite - get write access to private DMSNES context from a DM

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameter:
.  snesdm - private DMSNES context

   Level: developer

.seealso: `DMGetDMSNES()`
@*/
PetscErrorCode DMGetDMSNESWrite(DM dm, DMSNES *snesdm) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  PetscCheck(sdm->originaldm, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "DMSNES has a NULL originaldm");
  if (sdm->originaldm != dm) { /* Copy on write */
    DMSNES oldsdm = sdm;
    PetscCall(PetscInfo(dm, "Copying DMSNES due to write\n"));
    PetscCall(DMSNESCreate(PetscObjectComm((PetscObject)dm), &sdm));
    PetscCall(DMSNESCopy(oldsdm, sdm));
    PetscCall(DMSNESDestroy((DMSNES *)&dm->dmsnes));
    dm->dmsnes      = (PetscObject)sdm;
    sdm->originaldm = dm;
  }
  *snesdm = sdm;
  PetscFunctionReturn(0);
}

/*@C
   DMCopyDMSNES - copies a DM context to a new DM

   Logically Collective

   Input Parameters:
+  dmsrc - DM to obtain context from
-  dmdest - DM to add context to

   Level: developer

   Note:
   The context is copied by reference. This function does not ensure that a context exists.

.seealso: `DMGetDMSNES()`, `SNESSetDM()`
@*/
PetscErrorCode DMCopyDMSNES(DM dmsrc, DM dmdest) {
  PetscFunctionBegin;
  PetscValidHeaderSpecific(dmsrc, DM_CLASSID, 1);
  PetscValidHeaderSpecific(dmdest, DM_CLASSID, 2);
  if (!dmdest->dmsnes) PetscCall(DMSNESCreate(PetscObjectComm((PetscObject)dmdest), (DMSNES *)&dmdest->dmsnes));
  PetscCall(DMSNESCopy((DMSNES)dmsrc->dmsnes, (DMSNES)dmdest->dmsnes));
  PetscCall(DMCoarsenHookAdd(dmdest, DMCoarsenHook_DMSNES, NULL, NULL));
  PetscCall(DMRefineHookAdd(dmdest, DMRefineHook_DMSNES, NULL, NULL));
  PetscCall(DMSubDomainHookAdd(dmdest, DMSubDomainHook_DMSNES, DMSubDomainRestrictHook_DMSNES, NULL));
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetFunction - set SNES residual evaluation function

   Not Collective

   Input Parameters:
+  dm - DM to be used with SNES
.  f - residual evaluation function; see SNESFunction for details
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESSetFunction() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.  This makes the interface consistent regardless of whether the user interacts with a DM or
   not. If DM took a more central role at some later date, this could become the primary method of setting the residual.

.seealso: `DMSNESSetContext()`, `SNESSetFunction()`, `DMSNESSetJacobian()`, `SNESFunction`
@*/
PetscErrorCode DMSNESSetFunction(DM dm, PetscErrorCode (*f)(SNES, Vec, Vec, void *), void *ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNESWrite(dm, &sdm));
  if (f) sdm->ops->computefunction = f;
  if (ctx) {
    PetscContainer ctxcontainer;
    PetscCall(PetscContainerCreate(PetscObjectComm((PetscObject)sdm), &ctxcontainer));
    PetscCall(PetscContainerSetPointer(ctxcontainer, ctx));
    PetscCall(PetscObjectCompose((PetscObject)sdm, "function ctx", (PetscObject)ctxcontainer));
    sdm->functionctxcontainer = ctxcontainer;
    PetscCall(PetscContainerDestroy(&ctxcontainer));
  }
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetFunctionContextDestroy - set `SNES` residual evaluation context destroy function

   Not Collective

   Input Parameters:
+  dm - `DM` to be used with `SNES`
-  f - residual evaluation context destroy function

   Level: advanced

.seealso: `DMSNESSetFunction()`, `SNESSetFunction()`
@*/
PetscErrorCode DMSNESSetFunctionContextDestroy(DM dm, PetscErrorCode (*f)(void *)) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNESWrite(dm, &sdm));
  if (sdm->functionctxcontainer) PetscCall(PetscContainerSetUserDestroy(sdm->functionctxcontainer, f));
  PetscFunctionReturn(0);
}

PetscErrorCode DMSNESUnsetFunctionContext_Internal(DM dm) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNESWrite(dm, &sdm));
  PetscCall(DMSNESUnsetFunctionContext_DMSNES(sdm));
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetMFFunction - set SNES residual evaluation function used in applying the matrix-free Jacobian with -snes_mf_operator

   Logically Collective on dm

   Input Parameters:
+  dm - DM to be used with SNES
-  f - residual evaluation function; see SNESFunction for details

   Level: advanced

.seealso: `DMSNESSetContext()`, `SNESSetFunction()`, `DMSNESSetJacobian()`, `SNESFunction`, `DMSNESSetFunction()`
@*/
PetscErrorCode DMSNESSetMFFunction(DM dm, PetscErrorCode (*f)(SNES, Vec, Vec, void *), void *ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  if (f || ctx) { PetscCall(DMGetDMSNESWrite(dm, &sdm)); }
  if (f) sdm->ops->computemffunction = f;
  if (ctx) sdm->mffunctionctx = ctx;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESGetFunction - get SNES residual evaluation function

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameters:
+  f - residual evaluation function; see SNESFunction for details
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESGetFunction() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.

.seealso: `DMSNESSetContext()`, `DMSNESSetFunction()`, `SNESSetFunction()`, `SNESFunction`
@*/
PetscErrorCode DMSNESGetFunction(DM dm, PetscErrorCode (**f)(SNES, Vec, Vec, void *), void **ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  if (f) *f = sdm->ops->computefunction;
  if (ctx) {
    if (sdm->functionctxcontainer) PetscCall(PetscContainerGetPointer(sdm->functionctxcontainer, ctx));
    else *ctx = NULL;
  }
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetObjective - set SNES objective evaluation function

   Not Collective

   Input Parameters:
+  dm - DM to be used with SNES
.  obj - objective evaluation function; see SNESObjectiveFunction for details
-  ctx - context for residual evaluation

   Level: advanced

.seealso: `DMSNESSetContext()`, `SNESGetObjective()`, `DMSNESSetFunction()`
@*/
PetscErrorCode DMSNESSetObjective(DM dm, PetscErrorCode (*obj)(SNES, Vec, PetscReal *, void *), void *ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  if (obj || ctx) { PetscCall(DMGetDMSNESWrite(dm, &sdm)); }
  if (obj) sdm->ops->computeobjective = obj;
  if (ctx) sdm->objectivectx = ctx;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESGetObjective - get SNES objective evaluation function

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameters:
+  obj- residual evaluation function; see SNESObjectiveFunction for details
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESGetFunction() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.

.seealso: `DMSNESSetContext()`, `DMSNESSetObjective()`, `SNESSetFunction()`
@*/
PetscErrorCode DMSNESGetObjective(DM dm, PetscErrorCode (**obj)(SNES, Vec, PetscReal *, void *), void **ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  if (obj) *obj = sdm->ops->computeobjective;
  if (ctx) *ctx = sdm->objectivectx;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetNGS - set SNES Gauss-Seidel relaxation function

   Not Collective

   Input Parameters:
+  dm - DM to be used with SNES
.  f  - relaxation function, see SNESGSFunction
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESSetNGS() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.  This makes the interface consistent regardless of whether the user interacts with a DM or
   not. If DM took a more central role at some later date, this could become the primary method of setting the residual.

.seealso: `DMSNESSetContext()`, `SNESSetFunction()`, `DMSNESSetJacobian()`, `DMSNESSetFunction()`, `SNESGSFunction`
@*/
PetscErrorCode DMSNESSetNGS(DM dm, PetscErrorCode (*f)(SNES, Vec, Vec, void *), void *ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  if (f || ctx) { PetscCall(DMGetDMSNESWrite(dm, &sdm)); }
  if (f) sdm->ops->computegs = f;
  if (ctx) sdm->gsctx = ctx;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESGetNGS - get SNES Gauss-Seidel relaxation function

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameters:
+  f - relaxation function which performs Gauss-Seidel sweeps, see SNESGSFunction
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESGetNGS() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.  This makes the interface consistent regardless of whether the user interacts with a DM or
   not. If DM took a more central role at some later date, this could become the primary method of setting the residual.

.seealso: `DMSNESSetContext()`, `SNESGetNGS()`, `DMSNESGetJacobian()`, `DMSNESGetFunction()`, `SNESNGSFunction`
@*/
PetscErrorCode DMSNESGetNGS(DM dm, PetscErrorCode (**f)(SNES, Vec, Vec, void *), void **ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  if (f) *f = sdm->ops->computegs;
  if (ctx) *ctx = sdm->gsctx;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetJacobian - set SNES Jacobian evaluation function

   Not Collective

   Input Parameters:
+  dm - DM to be used with SNES
.  J - Jacobian evaluation function
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESSetJacobian() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.  This makes the interface consistent regardless of whether the user interacts with a DM or
   not. If DM took a more central role at some later date, this could become the primary method of setting the Jacobian.

.seealso: `DMSNESSetContext()`, `SNESSetFunction()`, `DMSNESGetJacobian()`, `SNESSetJacobian()`, `SNESJacobianFunction`
@*/
PetscErrorCode DMSNESSetJacobian(DM dm, PetscErrorCode (*J)(SNES, Vec, Mat, Mat, void *), void *ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  if (J || ctx) PetscCall(DMGetDMSNESWrite(dm, &sdm));
  if (J) sdm->ops->computejacobian = J;
  if (ctx) {
    PetscContainer ctxcontainer;
    PetscCall(PetscContainerCreate(PetscObjectComm((PetscObject)sdm), &ctxcontainer));
    PetscCall(PetscContainerSetPointer(ctxcontainer, ctx));
    PetscCall(PetscObjectCompose((PetscObject)sdm, "jacobian ctx", (PetscObject)ctxcontainer));
    sdm->jacobianctxcontainer = ctxcontainer;
    PetscCall(PetscContainerDestroy(&ctxcontainer));
  }
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetJacobianContextDestroy - set `SNES` Jacobian evaluation context destroy function

   Not Collective

   Input Parameters:
+  dm - `DM` to be used with `SNES`
-  f - Jacobian evaluation contex destroy function

   Level: advanced

.seealso: `DMSNESSetJacobian()`
@*/
PetscErrorCode DMSNESSetJacobianContextDestroy(DM dm, PetscErrorCode (*f)(void *)) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNESWrite(dm, &sdm));
  if (sdm->jacobianctxcontainer) PetscCall(PetscContainerSetUserDestroy(sdm->jacobianctxcontainer, f));
  PetscFunctionReturn(0);
}

PetscErrorCode DMSNESUnsetJacobianContext_Internal(DM dm) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNESWrite(dm, &sdm));
  PetscCall(DMSNESUnsetJacobianContext_DMSNES(sdm));
  PetscFunctionReturn(0);
}

/*@C
   DMSNESGetJacobian - get SNES Jacobian evaluation function

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameters:
+  J - Jacobian evaluation function; see SNESJacobianFunction for all calling sequence
-  ctx - context for residual evaluation

   Level: advanced

   Note:
   SNESGetJacobian() is normally used, but it calls this function internally because the user context is actually
   associated with the DM.  This makes the interface consistent regardless of whether the user interacts with a DM or
   not. If DM took a more central role at some later date, this could become the primary method of setting the Jacobian.

.seealso: `DMSNESSetContext()`, `SNESSetFunction()`, `DMSNESSetJacobian()`, `SNESJacobianFunction`
@*/
PetscErrorCode DMSNESGetJacobian(DM dm, PetscErrorCode (**J)(SNES, Vec, Mat, Mat, void *), void **ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  if (J) *J = sdm->ops->computejacobian;
  if (ctx) {
    if (sdm->jacobianctxcontainer) PetscCall(PetscContainerGetPointer(sdm->jacobianctxcontainer, ctx));
    else *ctx = NULL;
  }
  PetscFunctionReturn(0);
}

/*@C
   DMSNESSetPicard - set SNES Picard iteration matrix and RHS evaluation functions.

   Not Collective

   Input Parameters:
+  dm - DM to be used with SNES
.  b - RHS evaluation function
.  J - Picard matrix evaluation function
-  ctx - context for residual evaluation

   Level: advanced

.seealso: `SNESSetPicard()`, `DMSNESSetFunction()`, `DMSNESSetJacobian()`
@*/
PetscErrorCode DMSNESSetPicard(DM dm, PetscErrorCode (*b)(SNES, Vec, Vec, void *), PetscErrorCode (*J)(SNES, Vec, Mat, Mat, void *), void *ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  if (b) sdm->ops->computepfunction = b;
  if (J) sdm->ops->computepjacobian = J;
  if (ctx) sdm->pctx = ctx;
  PetscFunctionReturn(0);
}

/*@C
   DMSNESGetPicard - get SNES Picard iteration evaluation functions

   Not Collective

   Input Parameter:
.  dm - DM to be used with SNES

   Output Parameters:
+  b - RHS evaluation function; see SNESFunction for details
.  J  - RHS evaluation function; see SNESJacobianFunction for detailsa
-  ctx - context for residual evaluation

   Level: advanced

.seealso: `DMSNESSetContext()`, `SNESSetFunction()`, `DMSNESSetJacobian()`
@*/
PetscErrorCode DMSNESGetPicard(DM dm, PetscErrorCode (**b)(SNES, Vec, Vec, void *), PetscErrorCode (**J)(SNES, Vec, Mat, Mat, void *), void **ctx) {
  DMSNES sdm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMGetDMSNES(dm, &sdm));
  if (b) *b = sdm->ops->computepfunction;
  if (J) *J = sdm->ops->computepjacobian;
  if (ctx) *ctx = sdm->pctx;
  PetscFunctionReturn(0);
}