xref: /petsc/src/tao/linesearch/impls/unit/unit.c (revision 2a0dac0797dfdf4a2942fb34b57c2a93ae7a8c7a)

#include <petsc/private/taolinesearchimpl.h>

static PetscErrorCode TaoLineSearchDestroy_Unit(TaoLineSearch ls)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  ierr = PetscFree(ls->data);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

static PetscErrorCode TaoLineSearchSetFromOptions_Unit(PetscOptionItems *PetscOptionsObject,TaoLineSearch ls)
{
  PetscErrorCode ierr;
  PetscFunctionBegin;
  ierr = PetscOptionsHead(PetscOptionsObject,"No Unit line search options");CHKERRQ(ierr);
  ierr = PetscOptionsTail();CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

static PetscErrorCode TaoLineSearchView_Unit(TaoLineSearch ls,PetscViewer viewer)
{
  PetscErrorCode ierr;
  PetscBool      isascii;

  PetscFunctionBegin;
  ierr = PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii);CHKERRQ(ierr);
  if (isascii) {
    ierr=PetscViewerASCIIPrintf(viewer,"  Line Search: Unit Step.\n");CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode TaoLineSearchApply_Unit(TaoLineSearch ls,Vec x,PetscReal *f,Vec g,Vec step_direction)
{
  PetscErrorCode ierr;
  PetscReal      ftry;
  PetscReal      startf = *f;

  PetscFunctionBegin;
  /* Take unit step (newx = startx + 1.0*step_direction) */
  ierr = TaoLineSearchMonitor(ls, 0, *f, 0.0);CHKERRQ(ierr);
  ierr = VecAXPY(x,1.0,step_direction);CHKERRQ(ierr);
  ierr = TaoLineSearchComputeObjectiveAndGradient(ls,x,&ftry,g);CHKERRQ(ierr);
  ierr = TaoLineSearchMonitor(ls, 1, *f, 1.0);CHKERRQ(ierr);
  ierr = PetscInfo1(ls,"Tao Apply Unit Step: %4.4e\n",1.0);CHKERRQ(ierr);
  if (startf < ftry){
    ierr = PetscInfo2(ls,"Tao Apply Unit Step, FINCREASE: F old:= %12.10e, F new: %12.10e\n",(double)startf,(double)ftry);CHKERRQ(ierr);
  }
  *f = ftry;
  ls->step = 1.0;
  ls->reason=TAOLINESEARCH_SUCCESS;
  PetscFunctionReturn(0);
}

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

   Input Parameters:
.  tao - Tao context

   Level: advanced

.keywords: Tao, linesearch
@*/
PETSC_EXTERN PetscErrorCode TaoLineSearchCreate_Unit(TaoLineSearch ls)
{
  PetscFunctionBegin;
  ls->ops->setup = 0;
  ls->ops->reset = 0;
  ls->ops->apply = TaoLineSearchApply_Unit;
  ls->ops->view = TaoLineSearchView_Unit;
  ls->ops->destroy = TaoLineSearchDestroy_Unit;
  ls->ops->setfromoptions = TaoLineSearchSetFromOptions_Unit;
  PetscFunctionReturn(0);
}