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Subject: Re: [OMPI users] Send variable size of matrices
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-07-27 09:59:08


If you don't know the size a priori, you could always make a derived
type that covers the memory region you want, send the size of that
first, and then send the message with the real data (i.e., likely a
derived type).

On Jul 21, 2009, at 2:55 AM, Prasadcse Perera wrote:

> Hi,
> Its C bindings and if I clear the picture a bit more, what it does
> is partitioning the original matrix in to a set of sub matrices to
> be processed by the a other processes. And it seems that the only
> option left is to bundle off in to a temp buffer before sending as
> you have suggested. It would have been nice if there was a derived
> data type to do the trick :) ?
>
> Thanks,
> Prasad.
>
> On Tue, Jul 21, 2009 at 12:00 PM, Terry Frankcombe
> <terry_at_[hidden]> wrote:
> Which language bindings?
>
> For Fortran, consider pack or reshape. (I *think* whether array
> sections are bundled off into temporary, contiguous storage is
> implementation-dependent.)
>
> Isn't it easier to broadcast the size first?
>
>
> On Tue, 2009-07-21 at 11:53 +0530, Prasadcse Perera wrote:
> > Hi all,
> > I'm writing an application which requires sending some variable size
> > of sub matrices to a set of processes by a lead process who holds
> the
> > original matrix. Here, the matrices are square matrices and the
> > receiving process doesn't know the size of the receiving matrix. In
> > MPI_Bcast, I have seen that we can broadcast a whole matrix. Is
> there
> > a similar way to do this with a derived data type for the matrices
> > which we can send a matrix without looping the blocks ?.
> >
> > Thanks,
> > Prasad.
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-- 
Jeff Squyres
jsquyres_at_[hidden]