EPSSetWhichEigenpairs#

Specifies which portion of the spectrum is to be sought.

Synopsis#

#include "slepceps.h" 
PetscErrorCode EPSSetWhichEigenpairs(EPS eps,EPSWhich which)

Logically Collective

Input Parameters#

eps - the linear eigensolver context
which - the portion of the spectrum to be sought, see EPSWhich for possible values

Options Database Keys#

-eps_largest_magnitude - sets largest eigenvalues in magnitude
-eps_smallest_magnitude - sets smallest eigenvalues in magnitude
-eps_largest_real - sets largest real parts
-eps_smallest_real - sets smallest real parts
-eps_largest_imaginary - sets largest imaginary parts
-eps_smallest_imaginary - sets smallest imaginary parts
-eps_target_magnitude - sets eigenvalues closest to target
-eps_target_real - sets real parts closest to target
-eps_target_imaginary - sets imaginary parts closest to target
-eps_all - sets all eigenvalues in an interval or region

Notes#

Not all eigensolvers implemented in EPS 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 EPS_LARGEST_IMAGINARY and EPS_SMALLEST_IMAGINARY use the absolute value of the imaginary part for eigenvalue selection.

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

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

EPS_ALL is intended for use in combination with an interval (see EPSSetInterval()), when all eigenvalues within the interval are requested, or in the context of the EPSCISS solver for computing all eigenvalues in a region.