PEPSetWhichEigenpairs#

Specifies which portion of the spectrum is to be sought.

Synopsis#

#include "slepcpep.h" 
PetscErrorCode PEPSetWhichEigenpairs(PEP pep,PEPWhich which)

Logically Collective

Input Parameters#

pep - the polynomial eigensolver context
which - the portion of the spectrum to be sought, see PEPWhich for possible values

Options Database Keys#

-pep_largest_magnitude - sets largest eigenvalues in magnitude
-pep_smallest_magnitude - sets smallest eigenvalues in magnitude
-pep_largest_real - sets largest real parts
-pep_smallest_real - sets smallest real parts
-pep_largest_imaginary - sets largest imaginary parts
-pep_smallest_imaginary - sets smallest imaginary parts
-pep_target_magnitude - sets eigenvalues closest to target
-pep_target_real - sets real parts closest to target
-pep_target_imaginary - sets imaginary parts closest to target
-pep_all - sets all eigenvalues in an interval or region

Notes#

Not all eigensolvers implemented in PEP account for all the possible values of which. Also, some values make sense only for certain types of problems. If SLEPc is compiled for real numbers PEP_LARGEST_IMAGINARY and PEP_SMALLEST_IMAGINARY use the absolute value of the imaginary part for eigenvalue selection.

The target is a scalar value provided with PEPSetTarget().

The criterion PEP_TARGET_IMAGINARY is available only in case PETSc and SLEPc have been built with complex scalars.

PEP_ALL is intended for use in combination with an interval (see PEPSetInterval()), when all eigenvalues within the interval are requested, and also for computing all eigenvalues in a region with the PEPCISS solver.