[petsc-users] sparse matrix addition

[Jed Brown]

On Thu, Apr 14, 2011 at 05:48, Shiyuan <gshy2014 at gmail.com> wrote:

> I have two matrices A, B of different nonzero-pattern. Their size is about
> 60k*60k. I notices that MATAXPY() is extremely slow.


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.
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