On Fri, Nov 13, 2015 at 12:28 PM, Jed Brown <[email protected]> wrote:
> Matthew Knepley <[email protected]> writes: > > Something very strange is happening here. CG should converge > monotonically, > > but above it does not. What could be happening? > > Are you use -ksp_norm_type natural? CG is not monotone in other norms. > Yikes! I did not check that. Why do we have PRECONDITIONED as the default for CG? Matt Also, if boundary conditions are enforced using a nonsymmetric > formulation (for example), then you can get lack of monotonicity with CG > that may not be catastrophic. > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
