# QEPSetLeftVectorsWanted

Specifies which eigenvectors are required.

### Synopsis

    #include "slepcqep.h"
    PetscErrorCode QEPSetLeftVectorsWanted(QEP qep,PetscBool leftvecs)

Logically Collective on QEP

### Input Parameters

| qep | - the quadratic eigensolver context
| leftvecs | - whether left eigenvectors are required or not

### Options Database Keys

-qep_left_vectors <boolean> - Sets/resets the boolean flag 'leftvecs'

### Notes

If the user sets leftvecs=PETSC_TRUE then the solver uses a variant of the algorithm that computes both right and left eigenvectors. This is usually much more costly. This option is not available in all solvers.

### See Also

QEPGetLeftVectorsWanted()

Location: src/qep/interface/qepopts.c
Index of all QEP routines
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Index of all manual pages