[petsc-users] pcfieldsplitting not working for VI

[Lawrence Mitchell]

> On 29 Nov 2016, at 02:02, Justin Chang <jychang48 at gmail.com> wrote:
> 
> Why is this happening? It seems to me VINEWTONRSLS is not understanding that I have a two-field formulation. 

For the built in solvers, we set up a dmshell on the snes that knows how to do field splitting.  Because you set your snes up by hand, it isn't available. You'll need to call snes.setDM. The mixed finctionspace provides the correct dm via a ._dm property I think. 

Lawrence