> > You probably forgot to set the near null space. You can use > MatSetNearNullSpace (and maybe MatNullSpaceCreateRigidBody) or the more > hacky (IMO) PCSetCoordinates. It's important to have translational
No debate this is a hack and but people use it and I don't want to force them to commute the RBM (error prone and tedious). I've never heard of MatNullSpaceCreateRigidBody, and its easy so I'd recommend using it. I'll fix ex55 & ex56 to use this one day. > *and* rotational modes in the near null space that GAMG uses to build a > coarse space. This can be tricky in testing because if you just crush a cube (not a bad test problem) then there are not rotational modes in the solution and so rotational bodes don't help. Which, as Jed points out correctly is not a good general conclusion.
