slepc-3.22.2 2024-12-02
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# EPSSetEigenvalueComparison

Specifies the eigenvalue comparison function when EPSSetWhichEigenpairs() is set to EPS_WHICH_USER.

### Synopsis

    #include "slepceps.h"
    PetscErrorCode EPSSetEigenvalueComparison(EPS eps,SlepcEigenvalueComparisonFn *func,void* ctx)

Logically Collective

### Input Parameters

| eps | - eigensolver context obtained from EPSCreate()
| func | - the comparison function, see EPSEigenvalueComparisonFn for the calling sequence
| ctx | - a context pointer (the last parameter to the comparison function)

### 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

EPSSetWhichEigenpairs(), EPSWhich

### Level

advanced

### Location

src/eps/interface/epsopts.c

### Examples

src/eps/tutorials/ex18.c
Index of all EPS routines
Table of Contents for all manual pages
Index of all manual pages