[petsc-users] MatMPIBAIJSetPreallocationCSR i and j indices

Matteo Parsani parsani.matteo at gmail.com
Sun Sep 29 17:22:47 CDT 2013

Hi Barry and Jed,
just a curiosity and maybe a good point to learn something:

1- why are those* inconvenient *"convenience routines" ?

2 - why those routines *should not be used* when writing a fresh code or a
large re-factoring?

Thanks in advance.

On Sun, Sep 29, 2013 at 3:52 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> Barry Smith <bsmith at mcs.anl.gov> writes:
> >    We can do all this, but how much effort do we really want to make
> >    for supporting these inconvenient "convenience routines"?
> Not much, but this is a tiny amount of code.
> >    BTW: We should really label these function with
> >
> >    Level: Recommended only for legacy applications being quickly ported
> to PETSc
> >
> >     I really only want people who already have a working non-PETSc
> >     code that uses CSR directly already to use these routines so they
> >     can quickly try out PETSc, I never want someone writing fresh code
> >     or doing a large refactorization to EVER use these routines.
> Agreed.
> >> On second thought, why don't we just document that
> >> MatMPIBAIJSetPreallocationCSR respects MAT_ROW_ORIENTED within each
> >> block and let the user choose which they want to use?
> >
> >     Also there is no way to get this flag into
> MatCreateMPIBAIJWithArrays()
> The user calls MatSetOption before making that call and changes it
> afterward if they want.

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