Creating a new vector based on a already distributed set of Vecs

[Vijay S. Mahadevan]

There is more than 1 vector involved, with different data and layout
dependent on the physics and mesh. Since the different Vec objects in
systems have their own layout, I do not want to modify them or recreate
them. I just want to create an interface vector so that I can pass it on to
SNESSolve without having the hassle of synchronizing the individual vectors
in each system.

I am writing a multi-physics code and this global vector concept could be
applied to the global nonlinear residual and the global solution vector. It
doesn't make sense to recreate an entirely new vector and synchronizing
these at every call to the residual. And there lies my motivation. But if
you see an alternative way to approach this, I would be glad to hear it !

Sorry if I wasn’t too clear before.

-----Original Message-----
From: owner-petsc-users at mcs.anl.gov [mailto:owner-petsc-users at mcs.anl.gov]
On Behalf Of Matthew Knepley
Sent: Sunday, March 23, 2008 3:13 PM
To: petsc-users at mcs.anl.gov
Subject: Re: Creating a new vector based on a already distributed set of
Vecs

2008/3/23 Vijay S. Mahadevan <vijay.m at gmail.com>:
> Hi all,
>
>  I am sure the subject line wasn't too explanatory and so here goes.
>
>  I have a system which already has a Vec object created and distributed on
>  many processors based on domain decomposition. I could have several such
>  systems, each with a solution vector and a residual vector pertaining to
its
>  physics.
>
>  Now, can I create a global vector which would just be pointers to the
>  already existing vectors but from PETSc's point of view, appears to be a
>  globally valid, (and possibly weirdly) distributed vector. Such an option
>  will save the memory needed for the global vector and eliminates errors
as
>  to synchronization of the solution, residuals for the systems.

I do not understand what you want. If you want a vector with the same
layout,
use VecDuplicate(). If you want the same data, just use the Vec itself.

  Thanks,

    Matt

>  I was reading the documentation and found the PetscMap data structure.
But I
>  am not entirely sure if this is what I am looking for.
>
>  I hope that makes sense. I would appreciate any help you can provide to
>  point me in the right direction.
>
>  Cheers,
>  Vijay
>
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>  4:43 PM
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>
>



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