[petsc-users] PetscLayoutCreate for Fortran

[Hossein Talebi]

Thank you.

Well, only the first part. I move around the elements and identify the Halo
nodes etc. However, I do not renumber the vertices to be contiguous on the
CPUs like what you said.

BUT, I just noticed: I partition the domain based on the computational
wight of the elements which is different to that of Mat-Vec calculation.
This means my portioning may not be efficient for the solution process.

I think I will then go with the copy-in, solve, copy-out option.




On Wed, May 14, 2014 at 3:06 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> On May 13, 2014, at 11:42 AM, Hossein Talebi <talebi.hossein at gmail.com>
> wrote:
>
> >
> > I have already decomposed the Finite Element system using Metis. I just
> need to have the global rows exactly like how I define and I like to have
> the answer in the same layout so I don't have to move things around the
> processes again.
>
>    Metis tells you a good partitioning IT DOES NOT MOVE the elements to
> form a good partitioning. Do you move the elements around based on what
> metis told you and similarly do you renumber the elements (and vertices) to
> be contiquously numbered on each process with the first process getting the
> first set of numbers, the second process the second set of numbers etc?
>
>    If you do all that then when you create Vec and Mat you should simply
> set the local size (based on the number of local vertices on each process).
> You never need to use PetscLayoutCreate and in fact if your code was in C
> you would never use PetscLayoutCreate()
>
>    If you do not do all that then you need to do that first before you
> start calling PETSc.
>
>    Barry
>
> >
> > No, I don't need it for something else.
> >
> > Cheers
> > Hossein
> >
> >
> >
> >
> > On Tue, May 13, 2014 at 6:36 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
> > On Tue, May 13, 2014 at 11:07 AM, Hossein Talebi <
> talebi.hossein at gmail.com> wrote:
> > Hi All,
> >
> >
> > I am using PETSC from Fortran. I would like to define my own layout i.e.
> which row belongs to which CPU since I have already done the domain
> decomposition.  It appears that  "PetscLayoutCreate" and the other routine
> do this. But in the manual it says it is not provided in Fortran.
> >
> > Is there any way that I can do this using Fortran? Anyone has an example?
> >
> > You can do this for Vec and Mat directly. Do you want it for something
> else?
> >
> >   Thanks,
> >
> >      Matt
> >
> > Cheers
> > Hossein
> >
> >
> >
> >
> > --
> > 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
> >
> >
> >
> > --
> > www.permix.org
>
>


-- 
www.permix.org
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