#include "petscsnes.h" PetscErrorCode SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.
| r | - the vector that is used to store residuals (or NULL if you don't want it) | |
| f | - the function (or NULL if you don't want it); see SNESFunction for calling sequence details | |
| ctx | - the function context (or NULL if you don't want it) |
Notes: The vector r DOES NOT, in general contain the current value of the SNES nonlinear function