Subversion Repositories slepc-dev

/*

    The ST (spectral transformation) interface routines, callable by users.

*/

#include "src/st/stimpl.h"            /*I "slepcst.h" I*/

#undef __FUNCT__  

#define __FUNCT__ "STApply"

/*@

   STApply - Applies the spectral transformation operator to a vector, for

   instance (A - sB)^-1 B in the case of the shift-and-invert tranformation

   and generalized eigenproblem.

   Collective on ST and Vec

   Input Parameters:

+  st - the spectral transformation context

-  x  - input vector

   Output Parameter:

.  y - output vector

   Level: developer

.seealso: STApplyB()

@*/

PetscErrorCode STApply(ST st,Vec x,Vec y)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  PetscValidHeaderSpecific(x,VEC_COOKIE,2);

  PetscValidHeaderSpecific(y,VEC_COOKIE,3);

  if (x == y) SETERRQ(PETSC_ERR_ARG_IDN,"x and y must be different vectors");

  if (!st->setupcalled) { ierr = STSetUp(st); CHKERRQ(ierr); }

  ierr = PetscLogEventBegin(ST_Apply,st,x,y,0);CHKERRQ(ierr);

  st->applys++;

  ierr = (*st->ops->apply)(st,x,y);CHKERRQ(ierr);

  ierr = PetscLogEventEnd(ST_Apply,st,x,y,0);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STApplyB"

/*@

   STApplyB - Applies the B matrix to a vector.

   Collective on ST and Vec

   Input Parameters:

+  st - the spectral transformation context

-  x - input vector

   Output Parameter:

.  y - output vector

   Level: developer

.seealso: STApply()

@*/

PetscErrorCode STApplyB(ST st,Vec x,Vec y)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  PetscValidHeaderSpecific(x,VEC_COOKIE,2);

  PetscValidHeaderSpecific(y,VEC_COOKIE,3);

  if (x == y) SETERRQ(PETSC_ERR_ARG_IDN,"x and y must be different vectors");

  if (!st->setupcalled) { ierr = STSetUp(st); CHKERRQ(ierr); }

  if (x->id == st->xid && x->state == st->xstate) {

    ierr = VecCopy(st->Bx, y);CHKERRQ(ierr);

    PetscFunctionReturn(0);

  }

  ierr = PetscLogEventBegin(ST_ApplyB,st,x,y,0);CHKERRQ(ierr);

  ierr = (*st->ops->applyB)(st,x,y);CHKERRQ(ierr);

  ierr = PetscLogEventEnd(ST_ApplyB,st,x,y,0);CHKERRQ(ierr);

  st->xid = x->id;

  st->xstate = x->state;

  ierr = VecCopy(y,st->Bx);CHKERRQ(ierr);  

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STApplyB_Default"

PetscErrorCode STApplyB_Default(ST st,Vec x,Vec y)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  if( st->B ) {

    ierr = MatMult( st->B, x, y ); CHKERRQ(ierr);

  }

  else {

    ierr = VecCopy( x, y ); CHKERRQ(ierr);

  }

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STApplyTranspose"

/*@

   STApplyTranspose - Applies the transpose of the operator to a vector, for

   instance B^T(A - sB)^-T in the case of the shift-and-invert tranformation

   and generalized eigenproblem.

   Collective on ST and Vec

   Input Parameters:

+  st - the spectral transformation context

-  x  - input vector

   Output Parameter:

.  y - output vector

   Level: developer

.seealso: STApply()

@*/

PetscErrorCode STApplyTranspose(ST st,Vec x,Vec y)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  PetscValidHeaderSpecific(x,VEC_COOKIE,2);

  PetscValidHeaderSpecific(y,VEC_COOKIE,3);

  if (x == y) SETERRQ(PETSC_ERR_ARG_IDN,"x and y must be different vectors");

  if (!st->setupcalled) { ierr = STSetUp(st); CHKERRQ(ierr); }

  ierr = PetscLogEventBegin(ST_ApplyTranspose,st,x,y,0);CHKERRQ(ierr);

  ierr = (*st->ops->applytrans)(st,x,y);CHKERRQ(ierr);

  ierr = PetscLogEventEnd(ST_ApplyTranspose,st,x,y,0);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STComputeExplicitOperator"

/*@

    STComputeExplicitOperator - Computes the explicit operator associated

    to the eigenvalue problem with the specified spectral transformation.  

    Collective on ST

    Input Parameter:

.   st - the spectral transform context

    Output Parameter:

.   mat - the explicit operator

    Notes:

    This routine builds a matrix containing the explicit operator. For

    example, in generalized problems with shift-and-invert spectral

    transformation the result would be matrix (A - s B)^-1 B.

    This computation is done by applying the operator to columns of the

    identity matrix. Note that the result is a dense matrix.

    Level: advanced

.seealso: STApply()  

@*/

PetscErrorCode STComputeExplicitOperator(ST st,Mat *mat)

{

  PetscErrorCode ierr;

  Vec            in,out;

  PetscInt       i,M,m,*rows,start,end;

  PetscScalar    *array,one = 1.0;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  PetscValidPointer(mat,2);

  ierr = MatGetVecs(st->A,&in,&out);CHKERRQ(ierr);

  ierr = VecGetSize(out,&M);CHKERRQ(ierr);

  ierr = VecGetLocalSize(out,&m);CHKERRQ(ierr);

  ierr = VecGetOwnershipRange(out,&start,&end);CHKERRQ(ierr);

  ierr = PetscMalloc(m*sizeof(int),&rows);CHKERRQ(ierr);

  for (i=0; i<m; i++) rows[i] = start + i;

  ierr = MatCreateMPIDense(st->comm,m,m,M,M,PETSC_NULL,mat);CHKERRQ(ierr);

  for (i=0; i<M; i++) {

    ierr = VecSet(in,0.0);CHKERRQ(ierr);

    ierr = VecSetValues(in,1,&i,&one,INSERT_VALUES);CHKERRQ(ierr);

    ierr = VecAssemblyBegin(in);CHKERRQ(ierr);

    ierr = VecAssemblyEnd(in);CHKERRQ(ierr);

    ierr = STApply(st,in,out); CHKERRQ(ierr);

    ierr = VecGetArray(out,&array);CHKERRQ(ierr);

    ierr = MatSetValues(*mat,m,rows,1,&i,array,INSERT_VALUES);CHKERRQ(ierr);

    ierr = VecRestoreArray(out,&array);CHKERRQ(ierr);

  }

  ierr = PetscFree(rows);CHKERRQ(ierr);

  ierr = VecDestroy(in);CHKERRQ(ierr);

  ierr = VecDestroy(out);CHKERRQ(ierr);

  ierr = MatAssemblyBegin(*mat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);

  ierr = MatAssemblyEnd(*mat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STSetUp"

/*@

   STSetUp - Prepares for the use of a spectral transformation.

   Collective on ST

   Input Parameter:

.  st - the spectral transformation context

   Level: advanced

.seealso: STCreate(), STApply(), STDestroy()

@*/

PetscErrorCode STSetUp(ST st)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  PetscInfo(st,"Setting up new ST\n");

  if (st->setupcalled) PetscFunctionReturn(0);

  ierr = PetscLogEventBegin(ST_SetUp,st,0,0,0);CHKERRQ(ierr);

  if (!st->A) {SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"Matrix must be set first");}

  if (!st->type_name) {

    ierr = STSetType(st,STSHIFT);CHKERRQ(ierr);

  }

  if (st->w) { ierr = VecDestroy(st->w);CHKERRQ(ierr); }

  if (st->Bx) { ierr = VecDestroy(st->Bx);CHKERRQ(ierr); }

  ierr = MatGetVecs(st->A,&st->w,&st->Bx);CHKERRQ(ierr);

  st->xid = 0;

  if (st->ops->setup) {

    ierr = (*st->ops->setup)(st); CHKERRQ(ierr);

  }

  st->setupcalled = 1;

  ierr = PetscLogEventEnd(ST_SetUp,st,0,0,0);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STPostSolve"

/*@

   STPostSolve - Optional post-solve phase, intended for any actions that must

   be performed on the ST object after the eigensolver has finished.

   Collective on ST

   Input Parameters:

.  st  - the spectral transformation context

   Level: developer

.seealso: EPSSolve()

@*/

PetscErrorCode STPostSolve(ST st)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  if (st->ops->postsolve) {

    ierr = (*st->ops->postsolve)(st);CHKERRQ(ierr);

  }

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "STBackTransform"

/*@

   STBackTransform - Back-transformation phase, intended for

   spectral transformations which require to transform the computed

   eigenvalues back to the original eigenvalue problem.

   Collective on ST

   Input Parameters:

   st   - the spectral transformation context

   eigr - real part of a computed eigenvalue

   eigi - imaginary part of a computed eigenvalue

   Level: developer

.seealso: EPSBackTransform()

@*/

PetscErrorCode STBackTransform(ST st,PetscScalar* eigr,PetscScalar* eigi)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(st,ST_COOKIE,1);

  if (st->ops->backtr) {

    ierr = (*st->ops->backtr)(st,eigr,eigi);CHKERRQ(ierr);

  }

  PetscFunctionReturn(0);

}