[petsc-dev] chevy is messing with me

Jed Brown jedbrown at mcs.anl.gov
Wed Jan 2 23:19:13 CST 2013

Mark, the problem was that the Inode structure was not learning about the
diagonal change in MatScale(). Fixed now:


I also modified the example to get rid of all the preprocessor crud with
the same functionality (now at run-time instead of compile time).


On Tue, Dec 18, 2012 at 4:02 PM, Mark F. Adams <mark.adams at columbia.edu>wrote:

> I'm getting a floating point exception in the eigen estimator for cheby on
> the 2nd solve of ex56 (you need to uncomment the define of TwoSolve) when I
> use sor PC (runex56 uses jacobi so you need to change that).  I see this on
> Cray and my Mac.
> I also found that the eigen estimator was called before the first solve,
> and worked fine, but I set the eigen values so I don't want it computing
> eigen values.
> I can understand cheby being the eager beaver and recomputing eigen values
> when I set a new matrix, but this not the semantics that I prefer.
> So there seem to be three issues:
> 1) seems the floating point exception.  This only happens with a non-debug
> build.  I'm also using 64 bit indices.
> 2) computing eigenvalues even though I set them.
> 3) I would like to tell cheby not to recompute eigenvalues.
> Mark
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