[petsc-users] Zero diagonal jacobian

[Guido Giuntoli]

Hi I want to solve a problem with a matrix of this kind

       K   1
J =
       1   0

that represents an elastic problem with Lagrange multipliers, this system
is really small so I want to try a direct solver so I put -pc_type lu and
it fails, probably because of the 0 diagonal. Is there any way, using
petsc, to solve this in direct way ? like doing a shifting of columns or
something like that.

Thank you, Guido.