OK, I had gather all the pattern of A+A^T by my code. Can I call MatSeqAIJSetPreallocation again for enlarge preallocated memory? And then I can add 0 to some entry to make the matrix symmetrical.
> 2011/1/26 Gong Ding <gdiso at ustc.edu> > >> I have unsymmetrical jacobian matrix in MPIAIJ format (it is nearlly >> symmetric, I guess). I'd like to pad it to symmetrical pattern by just add 0 >> to corresponding matrix entry, which is required to some matrix partition >> step. > > > How are you obtaining the matrix? The best way is to preallocate those > extra zeros. > > A traditional purely algebraic way is to add the transpose (zeroed in this > case), but transpose is a bad operation to perform in parallel so I would > try to avoid it. >
