<div class="gmail_quote">On Wed, Sep 7, 2011 at 08:59, Kostas Kontzialis <span dir="ltr"><<a href="mailto:ckontzialis@lycos.com">ckontzialis@lycos.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
I'm using a matrix free method for the solution of the Navier-Stokes equaiotns on unstructured meshes. I want to numerically evaluate the elements of the residual's Jacobian matrix. I know where the non zero elements of the matrix are, but I read on the manual, that function MatGetColoring works only on sequential matrices. What should I do?</blockquote>
</div><br><div>It actually works for parallel matrices, but the underlying algorithm is serial. You can use it for tests and small problems, but it does not scale.</div><div><br></div><div>PETSc does not currently have a parallel graph coloring implementation, so you would have to compute a coloring yourself if you intend to use this for larger problem sizes.</div>