Dynamic allocation of Non zeros?

Barry Smith bsmith at mcs.anl.gov
Thu Nov 1 16:25:15 CDT 2007

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


> Thanks,
> Berend.

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