Problem with rectangular matrices

[Matthew Knepley]

On Tue, May 26, 2009 at 12:29 PM, Jed Brown <jed at 59a2.org> wrote:

> Matthew Knepley wrote:
>
> > It not computing Ab. Its computing Ab, A^2b, A^3b, etc.
>
> Of course, but that's all possible if A*b is computable.  Lisandro
> demonstrated that A*x was fine, which it better be because of how x was
> obtained.  Had he tried A*b, which is the first thing the KSP needs, the
> problem would have been obvious.


This is the whole point. b and x cannot have different local sizes in a
Krylov
method. It makes no sense.

  Matt


>
> Jed
>
-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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