Why MatSetSizes_SeqDense memzeroes values?

[Barry Smith]

   My guess is you can/should remove the zero completely.

   Barry

On Dec 3, 2008, at 12:09 PM, Lisandro Dalcin wrote:

> Please, review the changeset below, just pushed. Why is the memzero
> call being issued? Should it be completely removed?
>
> changeset:   13056:4ea189951503
> tag:         tip
> user:        Lisandro Dalcin <dalcinl at gmail.com>
> date:        Wed Dec 03 16:06:12 2008 -0200
> summary:     protect memzero call in MatSetSizes_SeqDense()
>
>
> I discovered the problem doing this:
>
> In [1]: from petsc4py import PETSc
> In [2]: A = PETSc.Mat().create()
> In [3]: A.setSizes([4,4])
> In [4]: A.setType('seqdense')
> In [5]: A.setSizes([4,4])
> ---------------------------------------------------------------------------
> Error                                     Traceback (most recent  
> call last)
> Error: error code 85
> [0] MatSetSizes() line 128 in src/mat/utils/gcreate.c
> [0] MatSetSizes_SeqDense() line 1529 in src/mat/impls/dense/seq/ 
> dense.c
> [0] PetscMemzero() line 189 in src/sys/utils/memc.c
> [0] Null argument, when expecting valid pointer
> [0] Trying to zero at a null pointer
>
>
> -- 
> Lisandro Dalcín
> ---------------
> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
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>