#include "petscsnes.h" #include "petscdm.h" PetscErrorCode MatSNESMFSetReuseBase(Mat J,PetscBool use)Logically Collective on Mat
| J | - the MatMFFD matrix | |
| use | - if true always reuse the base vector instead of recomputing f(u) even if the function in the MatSNESMF is not SNESComputeFunction() |
Notes: Care must be taken when using this routine to insure that the function provided to MatMFFDSetFunction(), call it F_MF() is compatible with with that provided to SNESSetFunction(), call it F_SNES(). That is, (F_MF(u + h*d) - F_SNES(u))/h has to approximate the derivative
Developer Notes: This was provided for the MOOSE team who desired to have a SNESSetFunction() function that could change configurations due to contacts while the function provided to MatMFFDSetFunction() cannot. Except for the possibility of changing the configuration both functions compute the same mathematical function so the differencing makes sense.