[petsc-users] how to speed up convergence

[Jed Brown]

On Fri, Nov 11, 2011 at 05:52, Konstantinos Kontzialis <
ckontzialis at lycos.com> wrote:

> However as you may see the convergence is very very slow? Any suggestions?


The linear solve is still diverging, so it's meaningless what the SNES
residual is. You need to monitor the true residual and find out why the
linear solve is failing. As I told you many times, you need to check the
scaling of the equations. It appears that you are seeing noise from
rounding error in finite differencing. This usually means that you need to
rescale your equations (choose different units). I also asked several times
about ordering of unknowns, but you never replied to that part either.
Please go through the items in this FAQ:

http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#kspdiverged
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