On 2/6/08, Ben Tay <zonexo at gmail.com> wrote: Because my grid's are > non-uniform in both x,y directions. Shouldn't that result in a > non-symmetric matrix? But I think it's still PD, positive definite. > Correct me if I'm wrong.
I believe you are wrong, unless you are using a non-standart spatial discretization method. Is your Poisson equation using some additional terms than the usual Laplace operator? For standard finite elements and finite diferences, your matrix should be symmetric. Of course, symmetry can be lost if you use the common trick of zeroing-out rows for boundary conditions (using MatZeroRows and related). But even in that case, I believe you can still use CG. -- Lisandro Dalc?n --------------- Centro Internacional de M?todos Computacionales en Ingenier?a (CIMEC) Instituto de Desarrollo Tecnol?gico para la Industria Qu?mica (INTEC) Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) PTLC - G?emes 3450, (3000) Santa Fe, Argentina Tel/Fax: +54-(0)342-451.1594
