> On May 24, 2017, at 2:21 AM, Danyang Su <danyang...@gmail.com> wrote: > > Dear All, > > I use PCFactorSetLevels for ILU and PCFactorSetFill for other preconditioning > in my code to help solve the problems that the default option is hard to > solve. However, I found the latter one, PCFactorSetFill does not take effect > for my problem.
SetFill doesn't affect the numerical answers at all. It is just a prediction you make of how much memory you expect to be used inside the factorization. > The matrices and rhs as well as the solutions are attached from the link > below. I obtain the solution using hypre preconditioner and it takes 7 and 38 > iterations for matrix 1 and matrix 2. However, if I use other preconditioner, > the solver just failed at the first matrix. I have tested this matrix using > the native sequential solver (not PETSc) with ILU preconditioning. If I set > the incomplete factorization level to 0, this sequential solver will take > more than 100 iterations. If I increase the factorization level to 1 or more, > it just takes several iterations. This remind me that the PC factor for this > matrices should be increased. However, when I tried it in PETSc, it just does > not work. > > Matrix and rhs can be obtained from the link below. > > https://eilinator.eos.ubc.ca:8443/index.php/s/CalUcq9CMeblk4R > > Would anyone help to check if you can make this work by increasing the PC > factor level or fill? > > Thanks and regards, > > Danyang > >