BAIJ and AIJ formats

Hong Zhang hzhang at
Sun Sep 28 16:58:42 CDT 2008


If your matrix can be stored as BAIJ
with dense blocks, then using BAIJ would be
more memory efficient.
See slides 42 of


On Sun, 28 Sep 2008, Manav Bhatia wrote:

> One more question:
> When is it advantageous to use BAIJ format instead of AIJ?
> Thanks,
> Manav
> On Sep 28, 2008, at 3:48 PM, Manav Bhatia wrote:
>> Hi,
>>   I have a few questions about the block format matrix.
>>    In the function: MatCreateSeqBAIJ, the arguments are
>> bs	- size of block
>> m	- number of rows
>> n	- number of columns
>> nz	- number of nonzero blocks per block row (same for all rows)
>> nnz	- array containing the number of nonzero blocks in the various block 
>> rows (possibly different for each block row) or PETSC_NULL
>> If I specify the nnz vector, then what is the dimension of this vector? Is 
>> that equal to the block size? If so, then is it assumed that all blocks 
>> have the same number of non-zeros per row?
>> If my blocks have different non-zero patterns, then should I use an AIJ 
>> format instead of a BAIJ format?
>> Thanks,
>> Manav

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