You might want to give a look at KSPSetDMActive() to use a DM description of the problem without forming your operator.
Best, Luc On 29 janv. 2014, at 11:09, Konstantinos Kontzialis wrote: > Dear all, > > I am using a matrix free method with a user defined preconditioner. > I run with the option -snes_mf_operator, but I get the following: > > Must call DMShellSetMatrix() or DMShellSetCreateMatrix()! > > Why is this happening? I use the TS library. > > Kostas
