[petsc-users] KSP diverging

Jed Brown jedbrown at mcs.anl.gov
Fri Dec 23 09:23:04 CST 2011

On Fri, Dec 23, 2011 at 07:43, Matthew Knepley <knepley at gmail.com> wrote:

> Even if you lose orthogonality, it will just stagnate since you always
> have the solution
> from the first few vectors. Likewise, I do not see how you can get an
> diverging sequence
> from restarting since you always have the last residual, you just stagnate.

The true residual can grow even though the estimate of the preconditioned
residual decreases monotonically. When you restart, you re-evaluate the
actual residual, which might be much larger.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20111223/300c4290/attachment.htm>

More information about the petsc-users mailing list