Are you always using MatSetValuesBlocked()? Did you look at the three matrices (before passing to the solve), do they all have the exact same nonzero structure and entries?
Barry > On Mar 18, 2015, at 1:45 PM, Chung-Kan Huang <[email protected]> wrote: > > So go back to my original question, > > I found the resuls look like > MATBAIJ == MATBAIJ2MATAIJ != MATAIJ > as I was expected to see > MATBAIJ != MATBAIJ2MATAIJ == MATAIJ > > because I thought MATBAIJ2MATAIJ & MATAIJ should use the same ILU > factorization. > > On Wed, Mar 18, 2015 at 1:33 PM, Barry Smith <[email protected]> wrote: > > As I think I said earlier: ILU will behave differently with BAIJ and AIJ > format. With BAIJ it uses a point block factorization (doing an ILU treating > each block in the matrix as a single point (and doing a dense factorization > for the inverse) while AIJ ignores the block size and just uses a point ILU. > So in general the convergence with BAIJ vs AIJ and ILU will be different; > usually BAIJ will converge better but it need not. > > Barry > > > On Mar 18, 2015, at 1:23 PM, Chung-Kan Huang <[email protected]> wrote: > > > > Sorry I didn't state my problem more accurate. The entries in the input > > matrixes and vectors​ are correct -- they have right values and correct > > nonzero structure. > > The KSP was setup so I can solve the lienar systems for an unsteady state > > convective problem. > > I use KSPBCGS + PCILU and so far I only try sequential on a very small > > problem. > > I wonder if blocked ilu is actually used in MATBAIJ2MATAIJ case. > > > > Thanks, > > > > > > > > > -- > Cheers >
