DSGetEigenvalueComparison

Gets the eigenvalue comparison function used for sorting.

Synopsis

#include "slepcds.h" 
PetscErrorCode DSGetEigenvalueComparison(DS ds,PetscErrorCode (**fun)(PetscScalar,PetscScalar,PetscScalar,PetscScalar,PetscInt*,void*),void** ctx)
Not Collective

Input Parameter

ds - the direct solver context

Output Parameters

fun - a pointer to the comparison function
ctx - a context pointer (the last parameter to the comparison function)

Calling Sequence of fun

 func(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 DSSetEigenvalueComparison()

Note

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

DSSort(), DSSetEigenvalueComparison()

Location: src/ds/interface/dsbasic.c
Index of all DS routines
Table of Contents for all manual pages
Index of all manual pages