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;
 30: $     SNESLineSearchGetSNES(linesearch,&snes);
 31: $     SNESLineSearchSetReason(linesearch,SNES_LINESEARCH_SUCCEEDED);
 32: $     SNESLineSearchGetVecs(linesearch,&X,&F,&Y,&W,&G);
 33: $     .. determine lambda using W and G as work vecs..
 34: $     VecAXPY(X,-lambda,Y);
 35: $     SNESComputeFunction(snes,X,F);
 36: $     SNESLineSearchComputeNorms(linesearch);
 37: $     return(0);
 38: $  }
 39: $
 40: $  ...
 41: $
 42: $  SNESGetLineSearch(snes, &linesearch);
 43: $  SNESLineSearchSetType(linesearch, SNESLINESEARCHSHELL);
 44: $  SNESLineSearchShellSetUserFunc(linesearch, shellfunc, NULL);

 46:    Level: advanced

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

 58:   PetscObjectTypeCompare((PetscObject)linesearch,SNESLINESEARCHSHELL,&flg);
 59:   if (flg) {
 60:     shell->ctx  = ctx;
 61:     shell->func = func;
 62:   }
 63:   return(0);
 64: }

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

 69:    Not Collective

 71:    Input Parameter:
 72: .     linesearch - the line search object

 74:    Output Parameters:
 75: +    func  - the user function; can be NULL if you do not want it
 76: -    ctx   - the user function context; can be NULL if you do not want it

 78:    Level: advanced

 80:    .seealso: SNESLineSearchShellSetUserFunc()
 81: @*/
 82: PetscErrorCode SNESLineSearchShellGetUserFunc(SNESLineSearch linesearch, SNESLineSearchUserFunc *func, void **ctx)
 83: {
 84:   PetscErrorCode       ierr;
 85:   PetscBool            flg;
 86:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;

 92:   PetscObjectTypeCompare((PetscObject)linesearch,SNESLINESEARCHSHELL,&flg);
 93:   if (flg) {
 94:     if (func) *func = shell->func;
 95:     if (ctx) *ctx  = shell->ctx;
 96:   }
 97:   return(0);
 98: }

100: static PetscErrorCode  SNESLineSearchApply_Shell(SNESLineSearch linesearch)
101: {
102:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;
103:   PetscErrorCode       ierr;

106:   /* apply the user function */
107:   if (shell->func) {
108:     (*shell->func)(linesearch, shell->ctx);
109:   } else SETERRQ(PetscObjectComm((PetscObject)linesearch), PETSC_ERR_USER, "SNESLineSearchShell needs to have a shell function set with SNESLineSearchShellSetUserFunc");
110:   return(0);
111: }

113: static PetscErrorCode  SNESLineSearchDestroy_Shell(SNESLineSearch linesearch)
114: {
115:   SNESLineSearch_Shell *shell = (SNESLineSearch_Shell*)linesearch->data;
116:   PetscErrorCode       ierr;

119:   PetscFree(shell);
120:   return(0);
121: }

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

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

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

132: Level: advanced

134: M*/
135: PETSC_EXTERN PetscErrorCode SNESLineSearchCreate_Shell(SNESLineSearch linesearch)
136: {

138:   SNESLineSearch_Shell *shell;
139:   PetscErrorCode       ierr;

142:   linesearch->ops->apply          = SNESLineSearchApply_Shell;
143:   linesearch->ops->destroy        = SNESLineSearchDestroy_Shell;
144:   linesearch->ops->setfromoptions = NULL;
145:   linesearch->ops->reset          = NULL;
146:   linesearch->ops->view           = NULL;
147:   linesearch->ops->setup          = NULL;

149:   PetscNewLog(linesearch,&shell);

151:   linesearch->data = (void*) shell;
152:   return(0);
153: }