xref: /petsc/src/tao/unconstrained/impls/lmvm/lmvm.c (revision 3c9e27cfca911a7d7e3219758be42726e83c4ab2)

#include "taolinesearch.h"
#include "../src/tao/matrix/lmvmmat.h"
#include "lmvm.h"

#define LMVM_BFGS                0
#define LMVM_SCALED_GRADIENT     1
#define LMVM_GRADIENT            2

#undef __FUNCT__
#define __FUNCT__ "TaoSolve_LMVM"
static PetscErrorCode TaoSolve_LMVM(TaoSolver tao)
{

  TAO_LMVM *lmP = (TAO_LMVM *)tao->data;

  PetscReal f, fold, gdx, gnorm;
  PetscReal step = 1.0;

  PetscReal delta;

  PetscErrorCode ierr;
  PetscInt stepType;
  PetscInt iter = 0;
  TaoSolverTerminationReason reason = TAO_CONTINUE_ITERATING;
  TaoLineSearchTerminationReason ls_status = TAOLINESEARCH_CONTINUE_ITERATING;

  PetscFunctionBegin;

  if (tao->XL || tao->XU || tao->ops->computebounds) {
    ierr = PetscPrintf(((PetscObject)tao)->comm,"WARNING: Variable bounds have been set but will be ignored by lmvm algorithm\n"); CHKERRQ(ierr);
  }

  /*  Check convergence criteria */
  ierr = TaoComputeObjectiveAndGradient(tao, tao->solution, &f, tao->gradient); CHKERRQ(ierr);
  ierr = VecNorm(tao->gradient,NORM_2,&gnorm); CHKERRQ(ierr);
  if (PetscIsInfOrNanReal(f) || PetscIsInfOrNanReal(gnorm)) {
    SETERRQ(PETSC_COMM_SELF,1, "User provided compute function generated Inf or NaN");
  }

  ierr = TaoMonitor(tao, iter, f, gnorm, 0.0, step, &reason); CHKERRQ(ierr);
  if (reason != TAO_CONTINUE_ITERATING) {
    PetscFunctionReturn(0);
  }

  /*  Set initial scaling for the function */
  if (f != 0.0) {
    delta = 2.0 * PetscAbsScalar(f) / (gnorm*gnorm);
  }
  else {
    delta = 2.0 / (gnorm*gnorm);
  }
  ierr = MatLMVMSetDelta(lmP->M,delta); CHKERRQ(ierr);

  /*  Set counter for gradient/reset steps */
  lmP->bfgs = 0;
  lmP->sgrad = 0;
  lmP->grad = 0;

  /*  Have not converged; continue with Newton method */
  while (reason == TAO_CONTINUE_ITERATING) {
    /*  Compute direction */
    ierr = MatLMVMUpdate(lmP->M,tao->solution,tao->gradient); CHKERRQ(ierr);
    ierr = MatLMVMSolve(lmP->M, tao->gradient, lmP->D); CHKERRQ(ierr);
    ++lmP->bfgs;

    /*  Check for success (descent direction) */
    ierr = VecDot(lmP->D, tao->gradient, &gdx); CHKERRQ(ierr);
    if ((gdx <= 0.0) || PetscIsInfOrNanReal(gdx)) {
      /* Step is not descent or direction produced not a number
         We can assert bfgsUpdates > 1 in this case because
         the first solve produces the scaled gradient direction,
         which is guaranteed to be descent

         Use steepest descent direction (scaled)
      */

      ++lmP->grad;

      if (f != 0.0) {
        delta = 2.0 * PetscAbsScalar(f) / (gnorm*gnorm);
      }
      else {
        delta = 2.0 / (gnorm*gnorm);
      }
      ierr = MatLMVMSetDelta(lmP->M, delta); CHKERRQ(ierr);
      ierr = MatLMVMReset(lmP->M); CHKERRQ(ierr);
      ierr = MatLMVMUpdate(lmP->M, tao->solution, tao->gradient); CHKERRQ(ierr);
      ierr = MatLMVMSolve(lmP->M,tao->gradient, lmP->D); CHKERRQ(ierr);

      /* On a reset, the direction cannot be not a number; it is a
	 scaled gradient step.  No need to check for this condition. */

      lmP->bfgs = 1;
      ++lmP->sgrad;
      stepType = LMVM_SCALED_GRADIENT;
    }
    else {
      if (1 == lmP->bfgs) {
        /*  The first BFGS direction is always the scaled gradient */
        ++lmP->sgrad;
        stepType = LMVM_SCALED_GRADIENT;
      }
      else {
        ++lmP->bfgs;
        stepType = LMVM_BFGS;
      }
    }
    ierr = VecScale(lmP->D, -1.0); CHKERRQ(ierr);

    /*  Perform the linesearch */
    fold = f;
    ierr = VecCopy(tao->solution, lmP->Xold); CHKERRQ(ierr);
    ierr = VecCopy(tao->gradient, lmP->Gold); CHKERRQ(ierr);

    ierr = TaoLineSearchApply(tao->linesearch, tao->solution, &f, tao->gradient, lmP->D, &step,&ls_status); CHKERRQ(ierr);
    ierr = TaoAddLineSearchCounts(tao); CHKERRQ(ierr);


    while (ls_status != TAOLINESEARCH_SUCCESS &&
	   ls_status != TAOLINESEARCH_SUCCESS_USER
	   && (stepType != LMVM_GRADIENT)) {
      /*  Linesearch failed */
      /*  Reset factors and use scaled gradient step */
      f = fold;
      ierr = VecCopy(lmP->Xold, tao->solution); CHKERRQ(ierr);
      ierr = VecCopy(lmP->Gold, tao->gradient); CHKERRQ(ierr);

      switch(stepType) {
      case LMVM_BFGS:
        /*  Failed to obtain acceptable iterate with BFGS step */
        /*  Attempt to use the scaled gradient direction */

        if (f != 0.0) {
          delta = 2.0 * PetscAbsScalar(f) / (gnorm*gnorm);
        }
        else {
          delta = 2.0 / (gnorm*gnorm);
        }
	ierr = MatLMVMSetDelta(lmP->M, delta); CHKERRQ(ierr);
	ierr = MatLMVMReset(lmP->M); CHKERRQ(ierr);
	ierr = MatLMVMUpdate(lmP->M, tao->solution, tao->gradient); CHKERRQ(ierr);
	ierr = MatLMVMSolve(lmP->M, tao->gradient, lmP->D); CHKERRQ(ierr);

        /* On a reset, the direction cannot be not a number; it is a
	   scaled gradient step.  No need to check for this condition. */

	lmP->bfgs = 1;
	++lmP->sgrad;
	stepType = LMVM_SCALED_GRADIENT;
	break;

      case LMVM_SCALED_GRADIENT:
        /* The scaled gradient step did not produce a new iterate;
	   attempt to use the gradient direction.
	   Need to make sure we are not using a different diagonal scaling */
	ierr = MatLMVMSetDelta(lmP->M, 1.0); CHKERRQ(ierr);
	ierr = MatLMVMReset(lmP->M); CHKERRQ(ierr);
	ierr = MatLMVMUpdate(lmP->M, tao->solution, tao->gradient); CHKERRQ(ierr);
	ierr = MatLMVMSolve(lmP->M, tao->gradient, lmP->D); CHKERRQ(ierr);

        lmP->bfgs = 1;
        ++lmP->grad;
        stepType = LMVM_GRADIENT;
        break;
      }
      ierr = VecScale(lmP->D, -1.0); CHKERRQ(ierr);

      /*  Perform the linesearch */
      ierr = TaoLineSearchApply(tao->linesearch, tao->solution, &f, tao->gradient, lmP->D, &step, &ls_status); CHKERRQ(ierr);
      ierr = TaoAddLineSearchCounts(tao); CHKERRQ(ierr);

    }

    if (ls_status != TAOLINESEARCH_SUCCESS &&
	ls_status != TAOLINESEARCH_SUCCESS_USER) {
      /*  Failed to find an improving point */
      f = fold;
      ierr = VecCopy(lmP->Xold, tao->solution); CHKERRQ(ierr);
      ierr = VecCopy(lmP->Gold, tao->gradient); CHKERRQ(ierr);
      step = 0.0;
      reason = TAO_DIVERGED_LS_FAILURE;
      tao->reason = TAO_DIVERGED_LS_FAILURE;
    }
    /*  Check for termination */
    ierr = VecNorm(tao->gradient, NORM_2, &gnorm); CHKERRQ(ierr);
    iter++;
    ierr = TaoMonitor(tao,iter,f,gnorm,0.0,step,&reason); CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "TaoSetUp_LMVM"
static PetscErrorCode TaoSetUp_LMVM(TaoSolver tao)
{
  TAO_LMVM *lmP = (TAO_LMVM *)tao->data;
  PetscInt n,N;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  /* Existence of tao->solution checked in TaoSetUp() */
  if (!tao->gradient) {ierr = VecDuplicate(tao->solution,&tao->gradient); CHKERRQ(ierr);  }
  if (!tao->stepdirection) {ierr = VecDuplicate(tao->solution,&tao->stepdirection); CHKERRQ(ierr);  }
  if (!lmP->D) {ierr = VecDuplicate(tao->solution,&lmP->D); CHKERRQ(ierr);  }
  if (!lmP->Xold) {ierr = VecDuplicate(tao->solution,&lmP->Xold); CHKERRQ(ierr);  }
  if (!lmP->Gold) {ierr = VecDuplicate(tao->solution,&lmP->Gold); CHKERRQ(ierr);  }

  /*  Create matrix for the limited memory approximation */
  ierr = VecGetLocalSize(tao->solution,&n); CHKERRQ(ierr);
  ierr = VecGetSize(tao->solution,&N); CHKERRQ(ierr);
  ierr = MatCreateLMVM(((PetscObject)tao)->comm,n,N,&lmP->M); CHKERRQ(ierr);
  ierr = MatLMVMAllocateVectors(lmP->M,tao->solution); CHKERRQ(ierr);


  PetscFunctionReturn(0);
}

/* ---------------------------------------------------------- */
#undef __FUNCT__
#define __FUNCT__ "TaoDestroy_LMVM"
static PetscErrorCode TaoDestroy_LMVM(TaoSolver tao)
{

  TAO_LMVM *lmP = (TAO_LMVM *)tao->data;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  if (tao->setupcalled) {
    ierr = VecDestroy(&lmP->Xold); CHKERRQ(ierr);
    ierr = VecDestroy(&lmP->Gold); CHKERRQ(ierr);
    ierr = VecDestroy(&lmP->D); CHKERRQ(ierr);
    ierr = MatDestroy(&lmP->M); CHKERRQ(ierr);
  }
  ierr = PetscFree(tao->data); CHKERRQ(ierr);
  tao->data = PETSC_NULL;

  PetscFunctionReturn(0);
}

/*------------------------------------------------------------*/
#undef __FUNCT__
#define __FUNCT__ "TaoSetFromOptions_LMVM"
static PetscErrorCode TaoSetFromOptions_LMVM(TaoSolver tao)
{

  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscOptionsHead("Limited-memory variable-metric method for unconstrained optimization"); CHKERRQ(ierr);
  ierr = TaoLineSearchSetFromOptions(tao->linesearch); CHKERRQ(ierr);
  ierr = PetscOptionsTail(); CHKERRQ(ierr);
  PetscFunctionReturn(0);

  PetscFunctionReturn(0);
}

/*------------------------------------------------------------*/
#undef __FUNCT__
#define __FUNCT__ "TaoView_LMVM"
static PetscErrorCode TaoView_LMVM(TaoSolver tao, PetscViewer viewer)
{

    TAO_LMVM *lm = (TAO_LMVM *)tao->data;
    PetscBool isascii;
    PetscErrorCode ierr;


    PetscFunctionBegin;
    ierr = PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii); CHKERRQ(ierr);
    if (isascii) {

        ierr = PetscViewerASCIIPushTab(viewer); CHKERRQ(ierr);
	ierr = PetscViewerASCIIPrintf(viewer, "BFGS steps: %D\n", lm->bfgs); CHKERRQ(ierr);
	ierr = PetscViewerASCIIPrintf(viewer, "Scaled gradient steps: %D\n", lm->sgrad); CHKERRQ(ierr);
	ierr = PetscViewerASCIIPrintf(viewer, "Gradient steps: %D\n", lm->grad); CHKERRQ(ierr);
        ierr = PetscViewerASCIIPopTab(viewer); CHKERRQ(ierr);
    } else {
      SETERRQ1(((PetscObject)tao)->comm,PETSC_ERR_SUP,"Viewer type %s not supported for TAO LMVM",((PetscObject)viewer)->type_name);
    }
    PetscFunctionReturn(0);
}

/* ---------------------------------------------------------- */

EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "TaoCreate_LMVM"
PetscErrorCode TaoCreate_LMVM(TaoSolver tao)
{

  TAO_LMVM *lmP;
  const char *morethuente_type = TAOLINESEARCH_MT;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  tao->ops->setup = TaoSetUp_LMVM;
  tao->ops->solve = TaoSolve_LMVM;
  tao->ops->view = TaoView_LMVM;
  tao->ops->setfromoptions = TaoSetFromOptions_LMVM;
  tao->ops->destroy = TaoDestroy_LMVM;

  ierr = PetscNewLog(tao,&lmP); CHKERRQ(ierr);
  lmP->D = 0;
  lmP->M = 0;
  lmP->Xold = 0;
  lmP->Gold = 0;

  tao->data = (void*)lmP;
  tao->max_it = 2000;
  tao->max_funcs = 4000;
  tao->fatol = 1e-4;
  tao->frtol = 1e-4;

  ierr = TaoLineSearchCreate(((PetscObject)tao)->comm,&tao->linesearch); CHKERRQ(ierr);
  ierr = TaoLineSearchSetType(tao->linesearch,morethuente_type); CHKERRQ(ierr);
  ierr = TaoLineSearchUseTaoSolverRoutines(tao->linesearch,tao); CHKERRQ(ierr);

  PetscFunctionReturn(0);
}
EXTERN_C_END