slepc-3.21.1 2024-04-26
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Specifies which portion of the spectrum is to be sought.


#include "slepcnep.h" 
PetscErrorCode NEPSetWhichEigenpairs(NEP nep,NEPWhich which)
Logically Collective

Input Parameters

nep  - eigensolver context obtained from NEPCreate()
which  - the portion of the spectrum to be sought

Options Database Keys

-nep_largest_magnitude  - Sets largest eigenvalues in magnitude
-nep_smallest_magnitude  - Sets smallest eigenvalues in magnitude
-nep_largest_real  - Sets largest real parts
-nep_smallest_real  - Sets smallest real parts
-nep_largest_imaginary  - Sets largest imaginary parts
-nep_smallest_imaginary  - Sets smallest imaginary parts
-nep_target_magnitude  - Sets eigenvalues closest to target
-nep_target_real  - Sets real parts closest to target
-nep_target_imaginary  - Sets imaginary parts closest to target
-nep_all  - Sets all eigenvalues in a region


The parameter 'which' can have one of these values

NEP_LARGEST_MAGNITUDE  - largest eigenvalues in magnitude (default)
NEP_SMALLEST_MAGNITUDE  - smallest eigenvalues in magnitude
NEP_LARGEST_REAL  - largest real parts
NEP_SMALLEST_REAL  - smallest real parts
NEP_LARGEST_IMAGINARY  - largest imaginary parts
NEP_SMALLEST_IMAGINARY  - smallest imaginary parts
NEP_TARGET_MAGNITUDE  - eigenvalues closest to the target (in magnitude)
NEP_TARGET_REAL  - eigenvalues with real part closest to target
NEP_TARGET_IMAGINARY  - eigenvalues with imaginary part closest to target
NEP_ALL  - all eigenvalues contained in a given region
NEP_WHICH_USER  - user defined ordering set with NEPSetEigenvalueComparison()

Not all eigensolvers implemented in NEP account for all the possible values stated above. If SLEPc is compiled for real numbers NEP_LARGEST_IMAGINARY and NEP_SMALLEST_IMAGINARY use the absolute value of the imaginary part for eigenvalue selection.

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

NEP_ALL is intended for use in the context of the CISS solver for computing all eigenvalues in a region.

See Also

NEPGetWhichEigenpairs(), NEPSetTarget(), NEPSetEigenvalueComparison(), NEPWhich





Index of all NEP routines
Table of Contents for all manual pages
Index of all manual pages