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

  4: typedef struct {
  5:   SNESLineSearchUserFunc func;
  6:   void                   *ctx;
  7: } SNESLineSearch_Shell;

  9: /*@C
 10:    SNESLineSearchShellSetUserFunc - Sets the user function for the SNESLineSearch Shell implementation.

 12:    Not Collective

 14:    Input Parameters:
 15: +  linesearch - SNESLineSearch context
 16: .  func - function implementing the linesearch shell.
 17: -  ctx - context for func

 19:    Calling sequence of func:
 20: +  linesearch - the linesearch instance
 21: -  ctx - the above mentioned context

 23:    Usage:

 25: $  PetscErrorCode shellfunc(SNESLineSearch linesearch,void * ctx)
 26: $  {
 27: $     Vec  X,Y,F,W,G;
 28: $     SNES snes;
 29: $     SNESLineSearchGetSNES(linesearch,&snes);
 30: $     SNESLineSearchSetReason(linesearch,SNES_LINESEARCH_SUCCEEDED);
 31: $     SNESLineSearchGetVecs(linesearch,&X,&F,&Y,&W,&G);
 32: $     .. determine lambda using W and G as work vecs..
 33: $     VecAXPY(X,-lambda,Y);
 34: $     SNESComputeFunction(snes,X,F);
 35: $     SNESLineSearchComputeNorms(linesearch);
 36: $     return 0;
 37: $  }
 38: $
 39: $  ...
 40: $
 41: $  SNESGetLineSearch(snes, &linesearch);
 42: $  SNESLineSearchSetType(linesearch, SNESLINESEARCHSHELL);
 43: $  SNESLineSearchShellSetUserFunc(linesearch, shellfunc, NULL);

 45:    Level: advanced

 47:    .seealso: SNESLineSearchShellGetUserFunc(), SNESLINESEARCHSHELL
 48: @*/
 49: PetscErrorCode SNESLineSearchShellSetUserFunc(SNESLineSearch linesearch, SNESLineSearchUserFunc func, void *ctx)
 50: {
 51:   PetscBool            flg;
 52:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;

 55:   PetscObjectTypeCompare((PetscObject)linesearch,SNESLINESEARCHSHELL,&flg);
 56:   if (flg) {
 57:     shell->ctx  = ctx;
 58:     shell->func = func;
 59:   }
 60:   return 0;
 61: }

 63: /*@C
 64:    SNESLineSearchShellGetUserFunc - Gets the user function and context for the shell implementation.

 66:    Not Collective

 68:    Input Parameter:
 69: .     linesearch - the line search object

 71:    Output Parameters:
 72: +    func  - the user function; can be NULL if you do not want it
 73: -    ctx   - the user function context; can be NULL if you do not want it

 75:    Level: advanced

 77:    .seealso: SNESLineSearchShellSetUserFunc()
 78: @*/
 79: PetscErrorCode SNESLineSearchShellGetUserFunc(SNESLineSearch linesearch, SNESLineSearchUserFunc *func, void **ctx)
 80: {
 81:   PetscBool            flg;
 82:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;

 87:   PetscObjectTypeCompare((PetscObject)linesearch,SNESLINESEARCHSHELL,&flg);
 88:   if (flg) {
 89:     if (func) *func = shell->func;
 90:     if (ctx) *ctx  = shell->ctx;
 91:   }
 92:   return 0;
 93: }

 95: static PetscErrorCode  SNESLineSearchApply_Shell(SNESLineSearch linesearch)
 96: {
 97:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;

 99:   /* apply the user function */
100:   if (shell->func) {
101:     (*shell->func)(linesearch, shell->ctx);
102:   } else SETERRQ(PetscObjectComm((PetscObject)linesearch), PETSC_ERR_USER, "SNESLineSearchShell needs to have a shell function set with SNESLineSearchShellSetUserFunc");
103:   return 0;
104: }

106: static PetscErrorCode  SNESLineSearchDestroy_Shell(SNESLineSearch linesearch)
107: {
108:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;

110:   PetscFree(shell);
111:   return 0;
112: }

114: /*MC
115:    SNESLINESEARCHSHELL - Provides context for a user-provided line search routine.

117: The user routine has one argument, the SNESLineSearch context.  The user uses the interface to
118: extract line search parameters and set them accordingly when the computation is finished.

120: Any of the other line searches may serve as a guide to how this is to be done.  There is also a basic
121: template in the documentation for SNESLineSearchShellSetUserFunc().

123: Level: advanced

125: M*/
126: PETSC_EXTERN PetscErrorCode SNESLineSearchCreate_Shell(SNESLineSearch linesearch)
127: {

129:   SNESLineSearch_Shell *shell;

131:   linesearch->ops->apply          = SNESLineSearchApply_Shell;
132:   linesearch->ops->destroy        = SNESLineSearchDestroy_Shell;
133:   linesearch->ops->setfromoptions = NULL;
134:   linesearch->ops->reset          = NULL;
135:   linesearch->ops->view           = NULL;
136:   linesearch->ops->setup          = NULL;

138:   PetscNewLog(linesearch,&shell);

140:   linesearch->data = (void*) shell;
141:   return 0;
142: }