PETSC_EXTERN_TYPEDEF typedef PetscErrorCode(NEPFunctionFn)(NEP nep,PetscScalar lambda,Mat T,Mat P,void *ctx);
| nep | - eigensolver context obtained from NEPCreate() | |
| 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 for private data for the function evaluation routine (may be NULL) |