[petsc-dev] strangness in Chebyshev estimate of eigenvalues

[Mark Adams]

On Tue, May 17, 2016 at 10:55 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Mark,
>
>    So it sounds like the right fix is to change the "random" option name
> to "noisy" and replace the use of the random number generator with Jed's
> hash and make it the default. (Where if you turn off the noisy it uses the
> right hand side which is useful for debugging the solvers)


So this means removing "PetscRandom      random;" from Cheby, I assume.


> If you make a pull request we'll move it through,
>
>    Thanks for bringing up the problem,
>
>   Barry
>
> > On May 17, 2016, at 9:44 PM, Jed Brown <jed at jedbrown.org> wrote:
> >
> > Barry Smith <bsmith at mcs.anl.gov> writes:
> >>  So are you proposing we have three options
> >>  KSPChebyshevEstEigSetRHSType() with (1) "use give rhs", (2) "use
> >>  random rhs", (3) "use hash scheme to produce same right hand side
> >>  independent of number of processes so long as the ordering stays the
> >>  same" or are you suggesting just bagging the random?
> >
> > Bag random for sure.
> >
> >>  or bagging also the right hand side and always just use the hash
> >>  scheme?
> >
> > I wouldn't have a problem with that.  The only nice thing about using
> > the RHS is that it doesn't depend on the ordering.
> >
> >>  By just using the hash scheme we can remove some current code and
> >>  options which is always a good thing... if they provide no added
> >>  value then they should be removed.
> >
> > Yes.
>
>
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