On Mar 18, 2012, at 11:39 AM, Matthew Knepley wrote:

> https://bitbucket.org/petsc/petsc-dev/changeset/7ae47bfbd6e9
>
> Why are we using the assembled flag to determine whether garray and colmap
> should be created? That seems like an abuse of the flag. Shouldn't we check
> for these when we need them?

This has always been the use of that flag since day one. That is the reason for the existence of that flag. Now you want to change the meaning of the flag.

Since your MatGetRow() MatSetValues() paradigm only works properly if no new nonzeros are introduced (otherwise people will get assembled errors after they've put in some values) what is wrong with my proposed solution of MatGetRowWrite() which is the correct interface for changing some values in the row but not the nonzero structure.

Your own metric. It complicates the interface. I have to know that I only want to change existing nonzeros, when it is

perfectly easy for SetValues() to detect this AND I already went and found all the places where this happens.

Matt

Barry

>
> Matt
>
> --
> 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