[petsc-dev] Matrix Options shown too many times in -help

[Aron Ahmadia]

Agreed, the overwhelming output from -h is tremendously annoying, and I
cannot always grep because I don't know what I'm grepping for :(

A

On Mon, Apr 18, 2011 at 3:43 PM, Jed Brown <jed at 59a2.org> wrote:

> Currently Matrix Options are printed in MatView_Private which is called
> from many places, e.g.
>
> MatAssemblyEnd
> MatZeroRowsColumns
> MatZeroRows
> MatLUFactorNumeric
> MatCholeskyFactorNumeric
>
> The problem here is that in time-stepping or a multigrid solve, it's common
> to have these functions called hundreds or thousands of times which is
> really overwhelming to -help output. One solution would be to store on a
> per-matrix basis whether help has been displayed and only view it once (this
> implies caching all the -mat_view_* options in the Mat, or calling with
> PetscOptionsGetBool after the first time). The options could even be moved
> to MatSetFromOptions, but that doesn't get called nearly as much as we would
> probably like.
>
> There is also the somewhat deeper problem of multiple objects with the same
> prefix (often no prefix). This is most visible for matrices inside of
> multigrid and/or fieldsplit. It is easy to have more than 20 matrices with
> no prefix so even if the multiple-output problem above was solved, it would
> still be fairly overwhelming. I think this is somewhat harder to fix because
> it would imply a per-prefix log of whether the option has been printed. I
> think that the one special case of no-prefix Mat would already be a
> significant usability improvement.
>
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