slepc-3.15.0 2021-03-31
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# DSSetRefined

Sets a flag to indicate that refined vectors must be computed.

### Synopsis

#include "slepcds.h"
PetscErrorCode DSSetRefined(DS ds,PetscBool ref)

Logically Collective on ds

### Input Parameter

 ds - the direct solver context ref - a boolean flag

### Notes

Normally the vectors returned in DS_MAT_X are eigenvectors of the projected matrix. With this flag activated, DSVectors() will return the right singular vector of the smallest singular value of matrix \tilde{A}-theta*I, where \tilde{A} is the extended (n+1)xn matrix and theta is the Ritz value. This is used in the refined Ritz approximation.

The default is PETSC_FALSE.