[petsc-users] MatCreateMPIAIJWithSplitArrays for symmetric matrix?

[Daniel Langr]

Jed,

MatCreateMPISBAIJWithArrays() copy the arrays, so it won't help me. I 
need all available memory for a matrix, so I cannot have it in memory twice.

Matrices emerge in new methods in nuclear structure computations 
(symmetry-adapted no-core shell models). I don't know how to allocate 
arrays exactly. But, I can generate a matrix into CSR format and then 
probably reorganize it (split into diagonal and off-diagonal entries).

Daniel

Dne 8.11.2010 11:19, Jed Brown napsal(a):
> On Mon, Nov 8, 2010 at 09:32, Daniel Langr <daniel.langr at gmail.com
> <mailto:daniel.langr at gmail.com>> wrote:
>
>     Is there an equivalent of MatCreateMPIAIJWithSplitArrays function
>     for symmetric matrices? Or does this function work with symmetric
>     matrices?
>
>
> There is MatCreateMPISBAIJWithArrays() in petsc-dev.
>
>     I work with symmetric matrices that are extremely expensive to
>     compute and I don't know their structure in advance. So to do
>     preallocation, it is not practical to compute a matrix twice -
>     firstly only to get d_nnz and o_nnz arrays and secondly to set
>     values. Now, I solve this problem by storing a matrix to a file
>     system, which is faster but still far from ideal. The best solution
>     I see is to compute a matrix only once, store it in memory as split
>     CSR arrays and then just call something like
>     MatCreateMPISBAIJWithSplitArrays.
>
>
> Where do the matrices come from?  How do you know how to allocate to
> create the arrays?
>
> Jed