<div class="gmail_quote">On Thu, Apr 14, 2011 at 05:48, Shiyuan <span dir="ltr"><<a href="mailto:gshy2014@gmail.com">gshy2014@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
I have two matrices A, B of different nonzero-pattern. Their size is about 60k*60k. I notices that MATAXPY() is extremely slow.</blockquote></div><br><div>What matrix format and what are you passing for MatStructure? With DIFFERENT_NONZERO_STRUCTURE, petsc-3.1 was not doing preallocation. This is fixed in petsc-dev.</div>