2: #include <petsc/private/taolinesearchimpl.h>

  6: static PetscErrorCode TaoLineSearchDestroy_Unit(TaoLineSearch ls)
  7: {
 10:   PetscFree(ls->data);
 11:   return(0);
 12: }

 16: static PetscErrorCode TaoLineSearchSetFromOptions_Unit(PetscOptionItems *PetscOptionsObject,TaoLineSearch ls)
 17: {
 20:   PetscOptionsHead(PetscOptionsObject,"No Unit line search options");
 21:   PetscOptionsTail();
 22:   return(0);
 23: }

 27: static PetscErrorCode TaoLineSearchView_Unit(TaoLineSearch ls,PetscViewer viewer)
 28: {
 30:   PetscBool      isascii;

 33:   PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii);
 34:   if (isascii) {
 35:     ierr=PetscViewerASCIIPrintf(viewer,"  Line Search: Unit Step.\n");
 36:   }
 37:   return(0);
 38: }

 42: static PetscErrorCode TaoLineSearchApply_Unit(TaoLineSearch ls,Vec x,PetscReal *f,Vec g,Vec step_direction)
 43: {
 45:   PetscReal      ftry;
 46:   PetscReal      startf = *f;

 49:   /* Take unit step (newx = startx + 1.0*step_direction) */
 50:   VecAXPY(x,1.0,step_direction);
 51:   TaoLineSearchComputeObjectiveAndGradient(ls,x,&ftry,g);
 52:   PetscInfo1(ls,"Tao Apply Unit Step: %4.4e\n",1.0);
 53:   if (startf < ftry){
 54:     PetscInfo2(ls,"Tao Apply Unit Step, FINCREASE: F old:= %12.10e, F new: %12.10e\n",(double)startf,(double)ftry);
 55:   }
 56:   *f = ftry;
 57:   ls->step = 1.0;
 58:   ls->reason=TAOLINESEARCH_SUCCESS;
 59:   return(0);
 60: }

 64: /*@C
 65:    TaoCreateUnitLineSearch - Always use step length of 1.0

 67:    Input Parameters:
 68: .  tao - Tao context

 70:    Level: advanced

 72: .keywords: Tao, linesearch
 73: @*/
 74: PETSC_EXTERN PetscErrorCode TaoLineSearchCreate_Unit(TaoLineSearch ls)
 75: {
 77:   ls->ops->setup = 0;
 78:   ls->ops->reset = 0;
 79:   ls->ops->apply = TaoLineSearchApply_Unit;
 80:   ls->ops->view = TaoLineSearchView_Unit;
 81:   ls->ops->destroy = TaoLineSearchDestroy_Unit;
 82:   ls->ops->setfromoptions = TaoLineSearchSetFromOptions_Unit;
 83:   return(0);
 84: }