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/*

       This file implements a wrapper to the TRLAN package

   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

   SLEPc - Scalable Library for Eigenvalue Problem Computations

   Copyright (c) 2002-2010, Universidad Politecnica de Valencia, Spain

   This file is part of SLEPc.

   SLEPc is free software: you can redistribute it and/or modify it under  the

   terms of version 3 of the GNU Lesser General Public License as published by

   the Free Software Foundation.

   SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY

   WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS

   FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for

   more details.

   You  should have received a copy of the GNU Lesser General  Public  License

   along with SLEPc. If not, see <http://www.gnu.org/licenses/>.

   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

*/

#include "src/eps/impls/external/trlan/trlanp.h"

PetscErrorCode EPSSolve_TRLAN(EPS);

/* Nasty global variable to access EPS data from TRLan_ */

static EPS globaleps;

#undef __FUNCT__  

#define __FUNCT__ "EPSSetUp_TRLAN"

PetscErrorCode EPSSetUp_TRLAN(EPS eps)

{

  PetscErrorCode ierr;

  EPS_TRLAN      *tr = (EPS_TRLAN *)eps->data;

  PetscFunctionBegin;

  if (eps->ncv) {

    if (eps->ncv<eps->nev) SETERRQ(1,"The value of ncv must be at least nev");

  }

  else eps->ncv = eps->nev;

  if (eps->mpd) PetscInfo(eps,"Warning: parameter mpd ignored\n");

  if (!eps->max_it) eps->max_it = PetscMax(1000,eps->n);

  if (!eps->ishermitian)

    SETERRQ(PETSC_ERR_SUP,"Requested method is only available for Hermitian problems");

  if (eps->isgeneralized)

    SETERRQ(PETSC_ERR_SUP,"Requested method is not available for generalized problems");

  if (!eps->which) eps->which = EPS_LARGEST_REAL;

  if (eps->which!=EPS_LARGEST_REAL && eps->which!=EPS_SMALLEST_REAL && eps->which!=EPS_TARGET_REAL)

    SETERRQ(1,"Wrong value of eps->which");

  tr->restart = 0;

  tr->maxlan = PetscBLASIntCast(eps->nev+PetscMin(eps->nev,6));

  if (tr->maxlan+1-eps->ncv<=0) { tr->lwork = PetscBLASIntCast(tr->maxlan*(tr->maxlan+10)); }

  else { tr->lwork = PetscBLASIntCast(eps->nloc*(tr->maxlan+1-eps->ncv) + tr->maxlan*(tr->maxlan+10)); }

  ierr = PetscMalloc(tr->lwork*sizeof(PetscReal),&tr->work);CHKERRQ(ierr);

  if (eps->extraction) {

     ierr = PetscInfo(eps,"Warning: extraction type ignored\n");CHKERRQ(ierr);

  }

  ierr = EPSAllocateSolution(eps);CHKERRQ(ierr);

  /* dispatch solve method */

  if (eps->leftvecs) SETERRQ(PETSC_ERR_SUP,"Left vectors not supported in this solver");

  eps->ops->solve = EPSSolve_TRLAN;

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "MatMult_TRLAN"

static PetscBLASInt MatMult_TRLAN(PetscBLASInt *n,PetscBLASInt *m,PetscReal *xin,PetscBLASInt *ldx,PetscReal *yout,PetscBLASInt *ldy)

{

  PetscErrorCode ierr;

  Vec            x,y;

  PetscBLASInt            i;

  PetscFunctionBegin;

  ierr = VecCreateMPIWithArray(((PetscObject)globaleps)->comm,*n,PETSC_DECIDE,PETSC_NULL,&x);CHKERRQ(ierr);

  ierr = VecCreateMPIWithArray(((PetscObject)globaleps)->comm,*n,PETSC_DECIDE,PETSC_NULL,&y);CHKERRQ(ierr);

  for (i=0;i<*m;i++) {

    ierr = VecPlaceArray(x,(PetscScalar*)xin+i*(*ldx));CHKERRQ(ierr);

    ierr = VecPlaceArray(y,(PetscScalar*)yout+i*(*ldy));CHKERRQ(ierr);

    ierr = STApply(globaleps->OP,x,y);CHKERRQ(ierr);

    ierr = IPOrthogonalize(globaleps->ip,0,PETSC_NULL,globaleps->nds,PETSC_NULL,globaleps->DS,y,PETSC_NULL,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);

    ierr = VecResetArray(x);CHKERRQ(ierr);

    ierr = VecResetArray(y);CHKERRQ(ierr);     

  }

  ierr = VecDestroy(x);CHKERRQ(ierr);

  ierr = VecDestroy(y);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "EPSSolve_TRLAN"

PetscErrorCode EPSSolve_TRLAN(EPS eps)

{

  PetscErrorCode ierr;

  PetscInt       i;

  PetscBLASInt   ipar[32], n, lohi, stat, ncv;

  EPS_TRLAN      *tr = (EPS_TRLAN *)eps->data;     

  PetscScalar    *pV;                              

  PetscFunctionBegin;

  ncv = PetscBLASIntCast(eps->ncv);

  n = PetscBLASIntCast(eps->nloc);

  if (eps->which==EPS_LARGEST_REAL || eps->which==EPS_TARGET_REAL) lohi = 1;

  else if (eps->which==EPS_SMALLEST_REAL) lohi = -1;

  else SETERRQ(1,"Wrong value of eps->which");

  globaleps = eps;

  ipar[0]  = 0;            /* stat: error flag */

  ipar[1]  = lohi;         /* smallest (lohi<0) or largest eigenvalues (lohi>0) */

  ipar[2]  = PetscBLASIntCast(eps->nev); /* number of desired eigenpairs */

  ipar[3]  = 0;            /* number of eigenpairs already converged */

  ipar[4]  = tr->maxlan;   /* maximum Lanczos basis size */

  ipar[5]  = tr->restart;  /* restarting scheme */

  ipar[6]  = PetscBLASIntCast(eps->max_it); /* maximum number of MATVECs */

  ipar[7]  = PetscBLASIntCast(MPI_Comm_c2f(((PetscObject)eps)->comm)); /* communicator */

  ipar[8]  = 0;            /* verboseness */

  ipar[9]  = 99;           /* Fortran IO unit number used to write log messages */

  ipar[10] = 1;            /* use supplied starting vector */

  ipar[11] = 0;            /* checkpointing flag */

  ipar[12] = 98;           /* Fortran IO unit number used to write checkpoint files */

  ipar[13] = 0;            /* number of flops per matvec per PE (not used) */

  tr->work[0] = eps->tol;  /* relative tolerance on residual norms */

  for (i=0;i<eps->ncv;i++) eps->eigr[i]=0.0;

  ierr = EPSGetStartVector(eps,0,eps->V[0],PETSC_NULL);CHKERRQ(ierr);

  ierr = VecGetArray(eps->V[0],&pV);CHKERRQ(ierr);

  TRLan_ ( MatMult_TRLAN, ipar, &n, &ncv, eps->eigr, pV, &n, tr->work, &tr->lwork );

  ierr = VecRestoreArray( eps->V[0], &pV );CHKERRQ(ierr);

  stat        = ipar[0];

  eps->nconv  = ipar[3];

  eps->its    = ipar[25];

  eps->reason = EPS_CONVERGED_TOL;

  if (stat!=0) { SETERRQ1(PETSC_ERR_LIB,"Error in TRLAN (code=%d)",stat);}

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "EPSDestroy_TRLAN"

PetscErrorCode EPSDestroy_TRLAN(EPS eps)

{

  PetscErrorCode ierr;

  EPS_TRLAN      *tr = (EPS_TRLAN *)eps->data;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(eps,EPS_COOKIE,1);

  ierr = PetscFree(tr->work);CHKERRQ(ierr);

  ierr = PetscFree(eps->data);CHKERRQ(ierr);

  ierr = EPSFreeSolution(eps);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

EXTERN_C_BEGIN

#undef __FUNCT__  

#define __FUNCT__ "EPSCreate_TRLAN"

PetscErrorCode EPSCreate_TRLAN(EPS eps)

{

  PetscErrorCode ierr;

  EPS_TRLAN      *trlan;

  PetscFunctionBegin;

  ierr = PetscNew(EPS_TRLAN,&trlan);CHKERRQ(ierr);

  PetscLogObjectMemory(eps,sizeof(EPS_TRLAN));

  eps->data                      = (void *) trlan;

  eps->ops->setup                = EPSSetUp_TRLAN;

  eps->ops->destroy              = EPSDestroy_TRLAN;

  eps->ops->backtransform        = EPSBackTransform_Default;

  eps->ops->computevectors       = EPSComputeVectors_Default;

  PetscFunctionReturn(0);

}

EXTERN_C_END