Date: 2022-03-04T17:39:31+00:00

Actual source code: linesearchshell.c

      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: }