1: #include <petsc/private/snesimpl.h>

  3: typedef struct {
  4:   PetscErrorCode (*solve)(SNES, Vec);
  5:   PetscCtx ctx;
  6: } SNES_Shell;

  8: /*@C
  9:   SNESShellSetSolve - Sets routine to apply as solver to a `SNESSHELL` `SNES` object

 11:   Logically Collective

 13:   Input Parameters:
 14: + snes  - the `SNES` nonlinear solver context
 15: - solve - the application-provided solver routine

 17:   Calling sequence of `apply`:
 18: + snes - the preconditioner, get the application context with `SNESShellGetContext()` provided with `SNESShellSetContext()`
 19: - xout - solution vector

 21:   Level: advanced

 23: .seealso: [](ch_snes), `SNES`, `SNESSHELL`, `SNESShellSetContext()`, `SNESShellGetContext()`
 24: @*/
 25: PetscErrorCode SNESShellSetSolve(SNES snes, PetscErrorCode (*solve)(SNES snes, Vec xout))
 26: {
 27:   PetscFunctionBegin;
 29:   PetscTryMethod(snes, "SNESShellSetSolve_C", (SNES, PetscErrorCode (*)(SNES, Vec)), (snes, solve));
 30:   PetscFunctionReturn(PETSC_SUCCESS);
 31: }

 33: static PetscErrorCode SNESDestroy_Shell(SNES snes)
 34: {
 35:   PetscFunctionBegin;
 36:   PetscCall(PetscFree(snes->data));
 37:   PetscFunctionReturn(PETSC_SUCCESS);
 38: }

 40: /*@
 41:   SNESShellGetContext - Returns the user-provided context associated with a `SNESSHELL`

 43:   Not Collective

 45:   Input Parameter:
 46: . snes - should have been created with `SNESSetType`(snes,`SNESSHELL`);

 48:   Output Parameter:
 49: . ctx - the user provided context

 51:   Level: advanced

 53:   Fortran Notes:
 54:   This only works when the context is a Fortran derived type or a `PetscObject`. Declare `ctx` with
 55: .vb
 56:   type(tUsertype), pointer :: ctx
 57: .ve

 59: .seealso: [](ch_snes), `SNES`, `SNESSHELL`, `SNESCreateShell()`, `SNESShellSetContext()`
 60: @*/
 61: PetscErrorCode SNESShellGetContext(SNES snes, PetscCtxRt ctx)
 62: {
 63:   PetscBool flg;

 65:   PetscFunctionBegin;
 67:   PetscAssertPointer(ctx, 2);
 68:   PetscCall(PetscObjectTypeCompare((PetscObject)snes, SNESSHELL, &flg));
 69:   if (!flg) *(void **)ctx = NULL;
 70:   else *(void **)ctx = ((SNES_Shell *)snes->data)->ctx;
 71:   PetscFunctionReturn(PETSC_SUCCESS);
 72: }

 74: /*@
 75:   SNESShellSetContext - sets the context for a `SNESSHELL`

 77:   Logically Collective

 79:   Input Parameters:
 80: + snes - the `SNESSHELL`
 81: - ctx  - the context

 83:   Level: advanced

 85: .seealso: [](ch_snes), `SNES`, `SNESSHELL`, `SNESCreateShell()`, `SNESShellGetContext()`
 86: @*/
 87: PetscErrorCode SNESShellSetContext(SNES snes, PetscCtx ctx)
 88: {
 89:   SNES_Shell *shell = (SNES_Shell *)snes->data;
 90:   PetscBool   flg;

 92:   PetscFunctionBegin;
 94:   PetscCall(PetscObjectTypeCompare((PetscObject)snes, SNESSHELL, &flg));
 95:   if (flg) shell->ctx = ctx;
 96:   PetscFunctionReturn(PETSC_SUCCESS);
 97: }

 99: static PetscErrorCode SNESSolve_Shell(SNES snes)
100: {
101:   SNES_Shell *shell = (SNES_Shell *)snes->data;

103:   PetscFunctionBegin;
104:   PetscCheck(shell->solve, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONGSTATE, "Must call SNESShellSetSolve() first");
105:   snes->reason = SNES_CONVERGED_ITS;
106:   PetscCall((*shell->solve)(snes, snes->vec_sol));
107:   PetscFunctionReturn(PETSC_SUCCESS);
108: }

110: static PetscErrorCode SNESShellSetSolve_Shell(SNES snes, PetscErrorCode (*solve)(SNES, Vec))
111: {
112:   SNES_Shell *shell = (SNES_Shell *)snes->data;

114:   PetscFunctionBegin;
115:   shell->solve = solve;
116:   PetscFunctionReturn(PETSC_SUCCESS);
117: }

119: /*MC
120:   SNESSHELL - a user provided nonlinear solver

122:    Level: advanced

124: .seealso: [](ch_snes), `SNESCreate()`, `SNES`, `SNESSetType()`, `SNESType`, `SNESShellGetContext()`, `SNESShellSetContext()`, `SNESShellSetSolve()`
125: M*/

127: PETSC_EXTERN PetscErrorCode SNESCreate_Shell(SNES snes)
128: {
129:   SNES_Shell *shell;

131:   PetscFunctionBegin;
132:   snes->ops->destroy = SNESDestroy_Shell;
133:   snes->ops->solve   = SNESSolve_Shell;

135:   snes->usesksp = PETSC_FALSE;
136:   snes->usesnpc = PETSC_FALSE;

138:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

140:   PetscCall(SNESParametersInitialize(snes));

142:   PetscCall(PetscNew(&shell));
143:   snes->data = (void *)shell;
144:   PetscCall(PetscObjectComposeFunction((PetscObject)snes, "SNESShellSetSolve_C", SNESShellSetSolve_Shell));
145:   PetscFunctionReturn(PETSC_SUCCESS);
146: }