Re: Dynamic allocation of Non zeros?

[Barry Smith <bsmith@xxxxxxxxxxx>]

On Nov 1, 2007, at 4:17 PM, Berend van Wachem wrote:

> Hi Barry,
>
>
> >    Perhaps you could describe how your matrix entries are generated  
> > and we can suggest a
> > preallocation scheme?
>
> Are there examples of preallocation schemes for PETSc? For instance,  
> if I would like to solve Poisson equation on an irregular grid (9  
> point stencil in 2d and 27 in 3d) on n processors?

  This would depend on how you store your grid information; is it  
treated as unstructured? For structured or semi-structured
take a look at DAGetMatrix2d_MPIAIJ() in src/dm/da/utils/fdda.c

  Barry


> Thanks,
> Berend.