Barry Smith wrote: > > On Nov 6, 2007, at 3:29 AM, Zhifeng Sheng wrote: > >> Dear all >> >> I tried to reorder my the preconditioner with different reordering >> schema. >> >> All worked well for ILU, but does not make any difference on ICC. It >> seems that the reordering schema does not work for ICC at all.... >> >> Is it supposed to be like this? > > > Yes, with sbaij only the upper triangular part of the matrix is > stored; hence reordering doesn't make sense > since the values needed in the reordered form are not available. You > can use the SeqAIJ format if you want > to do reorderings with the ICC. > > Barry > >> >> >> PS: I have a symmetric matrix and I would like to save some memory. I >> used SBAIJ with block=1, but some told me it's not efficient ... > > > SBAIJ with block=1 is just as efficient as AIJ! The is seperate code > for each block size. > > Barry > >> >> So... what can I do to save some memory on matrix and preconditioner? >> >> >> Thank you >> Best regards >> Zhifeng Sheng >> > Thank you for your answer.
Could you please tell me if I can first assemble the matrix with a sufficiently large nonzero number per row and then release the redundent memory after the assembly is done? and what does MatCompress do? I tried it on my matrix, nothing happened ... Thank you Best regards
