Dear all, Happy new year!
I'm using the matrix-free method to solve NS equations. I call the SNESSetFunction to set the RHS function. I think SNES also uses that RHS function to evaluate the matrix vector product. But I want to set one function to evaluate the residual, and another different function to evaluate the matrix vector product. How can I do that? Does MatMFFDSetFunction do this job? Any suggestion is appreciated. Thank you. Song
