slepc-3.21.1 2024-04-26
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Specifies the eigenvalue comparison function when NEPSetWhichEigenpairs() is set to NEP_WHICH_USER.


#include "slepcnep.h" 
PetscErrorCode NEPSetEigenvalueComparison(NEP nep,PetscErrorCode (*comp)(PetscScalar ar,PetscScalar ai,PetscScalar br,PetscScalar bi,PetscInt *res,void *ctx),void* ctx)
Logically Collective

Input Parameters

nep  - eigensolver context obtained from NEPCreate()
comp  - a pointer to the comparison function
ctx  - a context pointer (the last parameter to the comparison function)

Calling sequence of comp

 PetscErrorCode comp(PetscScalar ar,PetscScalar ai,PetscScalar br,PetscScalar bi,PetscInt *res,void *ctx)
ar  - real part of the 1st eigenvalue
ai  - imaginary part of the 1st eigenvalue
br  - real part of the 2nd eigenvalue
bi  - imaginary part of the 2nd eigenvalue
res  - result of comparison
ctx  - optional context, as set by NEPSetEigenvalueComparison()


The returning parameter 'res' can be
negative  - if the 1st eigenvalue is preferred to the 2st one
zero  - if both eigenvalues are equally preferred
positive  - if the 2st eigenvalue is preferred to the 1st one

See Also

NEPSetWhichEigenpairs(), NEPWhich





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