Parallel ISCreateGeneral()

[Matthew Knepley]

On Nov 18, 2007 11:52 AM, Tim Stitt <timothy.stitt at ichec.ie> wrote:
> Matt,
>
> It is in setup for MatLUFactorSymbolic() and MatLUFactorNumeric() calls
> which require index sets. I have distributed my rows across the
> processes and now just a bit confused about the arguments to the
> ISCreateGeneral() routine to set up the IS sets used by the Factor
> routines in parallel.
>
> So my basic question is what in general is the length and integers that
> get passed to ISCreateGeneral() when doing this type of calculation in
> parallel? Are they local index values (0..#rows on process-1) or do they
> refer to the distributed indices of the global matrix?

To be consistent, these would be local sizes and global numberings. However,
I am not sure why you would be doing this. I do not believe any of the parallel
LU packages accept an ordering from the user (they calculate their own),
and I would really only use them from a KSP (or PC at the least).

  Matt

> Tim.
>
>
> Matthew Knepley wrote:
> > On Nov 18, 2007 11:34 AM, Tim Stitt <timothy.stitt at ichec.ie> wrote:
> >
> >> OK..so I should be using the aggregate length returned by
> >> MatGetOwnershipRange() routine?
> >>
> >
> > If you are using it to permute a Mat, yes.
> >
> >   Matt
> >
> >
> >> Thanks Matt for you help.
> >>
> >>
> >> Matthew Knepley wrote:
> >>
> >>> IS are not really parallel, so all the lengths, etc. only refer to local things.
> >>>
> >>>   Matt
> >>>
> >>> On Nov 18, 2007 11:22 AM, Tim Stitt <timothy.stitt at ichec.ie> wrote:
> >>>
> >>>
> >>>> Hi all,
> >>>>
> >>>> Just wanted to know if the "the length of the index set" for a call to
> >>>> ISCreateGeneral() in a parallel code, is a global length, or the length
> >>>> of the local elements on each process?
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Tim.
> >>>>
> >>>> --
> >>>> Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
> >>>> HPC Application Consultant - ICHEC (www.ichec.ie)
> >>>>
> >>>> Dublin Institute for Advanced Studies
> >>>> 5 Merrion Square - Dublin 2 - Ireland
> >>>>
> >>>> +353-1-6621333 (tel) / +353-1-6621477 (fax)
> >>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >> --
> >> Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
> >> HPC Application Consultant - ICHEC (www.ichec.ie)
> >>
> >> Dublin Institute for Advanced Studies
> >> 5 Merrion Square - Dublin 2 - Ireland
> >>
> >> +353-1-6621333 (tel) / +353-1-6621477 (fax)
> >>
> >>
> >>
> >
> >
> >
> >
>
>
> --
> Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
> HPC Application Consultant - ICHEC (www.ichec.ie)
>
> Dublin Institute for Advanced Studies
> 5 Merrion Square - Dublin 2 - Ireland
>
> +353-1-6621333 (tel) / +353-1-6621477 (fax)
>
>



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What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which
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