<div class="gmail_quote">On Tue, May 31, 2011 at 01:31, Matthew Knepley <span dir="ltr"><<a href="mailto:knepley@gmail.com">knepley@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div>You generate a NaN somewhere. I usually check for this using norms, since NaN propagate. Check the norm</div><div>of the rhs, initial solution, matrix, etc.</div></blockquote></div><br><div>You can also run with -fp_trap, possibly in a debugger, and it should break at the first place the NaN was computed. This works better (on more platforms) with petsc-dev.</div>