space allocation for a parallel matrix

[Satish Balay]

One issue that migh be cause for confusion is: for sparse mat-vec -
only a part of the vec from other procs is needed.

This part is communicated during Mat-Vec [using VecScatters]

So the 'whole 'vec' is not stored on each proc..

Satish

On Tue, 3 Feb 2009, Matthew Knepley wrote:

> On Tue, Feb 3, 2009 at 9:56 AM, Yixun Liu <enjoywm at cs.wm.edu> wrote:
> > It means that it is better to set n to be equal to the column to avoid
> > the communication. Right? If it does, I am confusing why we need this
> > parameter. Just for dealing with very large vector x?
> > Thanks.!
> 
> No. Please take a look at the book I recommended. If you do as you suggest,
> this is no longer parallel computing.
> 
>   Matt
> 
>