You can solve this problem by using the PETSc interface to MUMPS. See this post, replace -pc_type hypre by -pc_type lu (though for simple problems such as heat equations and such, you should definitely use hypre and not MUMPS).
You can solve this problem by using the PETSc interface to MUMPS. See this post, replace -pc_type hypre by -pc_type lu (though for simple problems such as heat equations and such, you should definitely use hypre and not MUMPS).