slepc-3.20.1 2023-11-27
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# NEPSetFunction

Sets the function to compute the nonlinear Function T(lambda) as well as the location to store the matrix.

### Synopsis

    #include "slepcnep.h"
    PetscErrorCode NEPSetFunction(NEP nep,Mat A,Mat B,PetscErrorCode (*fun)(NEP nep,PetscScalar lambda,Mat T,Mat P,void *ctx),void *ctx)

Collective

### Input Parameters

| nep | - the NEP context
| A | - Function matrix
| B | - preconditioner matrix (usually same as A)
| fun | - Function evaluation routine (if NULL then NEP retains any previously set value)
| ctx | - [optional] user-defined context for private data for the Function evaluation routine (may be NULL) (if NULL then NEP retains any previously set value)

### Calling sequence of fun

     PetscErrorCode fun(NEP nep,PetscScalar lambda,Mat T,Mat P,void *ctx)

| nep | - the NEP context
| lambda | - the scalar argument where T(.) must be evaluated
| T | - matrix that will contain T(lambda)
| P | - (optional) different matrix to build the preconditioner
| ctx | - (optional) user-defined context, as set by NEPSetFunction()

### See Also

NEPGetFunction(), NEPSetJacobian()

### Level

beginner

### Location

src/nep/interface/nepbasic.c

### Examples

src/nep/tutorials/ex20.c
src/nep/tutorials/ex20f90.F90
src/nep/tutorials/ex21.c
src/nep/tutorials/ex27.c
src/nep/tutorials/ex27f90.F90
src/nep/tutorials/ex54f90.F90
Index of all NEP routines
Table of Contents for all manual pages
Index of all manual pages