On Nov 13, 2011, at 4:45 PM, Matthew Knepley wrote:

> On Sun, Nov 13, 2011 at 10:44 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> On Sun, Nov 13, 2011 at 16:36, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 1) It is legitimate to call KSPSetOperators with a null Amat so this is a bug 
> that crashes large parts of PETSc
> 
> This logic should be moved much later (like to KSPSetUp()).
> 
> I disagree, since SetOperators() is where we know that the matrix is changing.

  Yes, but the matrix may not exist.

> 
>    Matt
>  
>  
> 
> 2) Do you really want to do this? I am not sure I like it.
> 
> I think that attaching the null space to the Mat should be the preferred way 
> to communicate it, especially in the case of a deeply nested hierarchy.
> 
> 
> 
> -- 
> 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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