[petsc-users] Null spaces with fieldsplit preconditioning

Hello, I have a mixed FEM system, for which the null space is constant functions in one of the sub spaces. That is, I have W = V * Q and the null space is a constant function in Q (and zero in V). If I assemble the operator, I get a block structure: X = [A B, C D] When I solve this

Re: [petsc-users] Null spaces with fieldsplit preconditioning

On Wed, Mar 12, 2014 at 6:44 AM, Lawrence Mitchell lawrence.mitch...@imperial.ac.uk wrote: Hello, I have a mixed FEM system, for which the null space is constant functions in one of the sub spaces. That is, I have W = V * Q and the null space is a constant function in Q (and zero in V).