/*
Shift spectral transformation, applies (A + sigma I) as operator, or
inv(B)(A + sigma B) for generalized problems
*/
#include "src/st/stimpl.h" /*I "slepcst.h" I*/
#undef __FUNCT__
#define __FUNCT__ "STApply_Shift"
int STApply_Shift(ST st,Vec x,Vec y)
{
int ierr;
Vec w;
PetscFunctionBegin;
if (st->B) {
/* generalized eigenproblem: y = (B^-1 A + sI) x */
w = (Vec) st->data;
ierr = MatMult(st->A,x,w);CHKERRQ(ierr);
ierr = STAssociatedKSPSolve(st,w,y);CHKERRQ(ierr);
}
else {
/* standard eigenproblem: y = (A + sI) x */
ierr = MatMult(st->A,x,y);CHKERRQ(ierr);
}
if (st->sigma != 0.0) {
ierr = VecAXPY(&st->sigma,x,y);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "STBackTransform_Shift"
int STBackTransform_Shift(ST st,PetscScalar *eigr,PetscScalar *eigi)
{
PetscFunctionBegin;
if (eigr) *eigr -= st->sigma;
PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "STSetUp_Shift"
static int STSetUp_Shift(ST st)
{
int ierr;
Vec w;
PetscFunctionBegin;
if (st->B) {
ierr = VecDuplicate(st->vec,&w);CHKERRQ(ierr);
st->data = (void *) w;
ierr = KSPSetOperators(st->ksp,st->B,st->B,DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);
ierr = KSPSetUp(st->ksp);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "STDestroy_Shift"
static int STDestroy_Shift(ST st)
{
int ierr;
Vec w;
PetscFunctionBegin;
if (st->data) {
w = (Vec) st->data;
ierr = VecDestroy(w);CHKERRQ(ierr);
}
PetscFunctionReturn(0);
}
EXTERN_C_BEGIN
#undef __FUNCT__
#define __FUNCT__ "STCreate_Shift"
int STCreate_Shift(ST st)
{
PetscFunctionBegin;
st->numberofshifts = 1;
st->ops->apply = STApply_Shift;
st->ops->backtr = STBackTransform_Shift;
st->ops->destroy = STDestroy_Shift;
st->ops->setup = STSetUp_Shift;
st->checknullspace = 0;
PetscFunctionReturn(0);
}
EXTERN_C_END