On Wed, May 24, 2017 at 12:50 PM, Danyang Su <[email protected]> wrote:
> Hi Matthew and Barry, > > Thanks for the quick response. > > I also tried superlu and mumps, both work but it is about four times > slower than ILU(dt) prec through hypre, with 24 processors I have tested. > You mean the total time is 4x? And you are taking hundreds of iterates? That seems hard to believe, unless you are dropping a huge number of elements. > When I look into the convergence information, the method using ILU(dt) > still takes 200 to 3000 linear iterations for each newton iteration. One > reason is this equation is hard to solve. As for the general cases, the > same method works awesome and get very good speedup. > I do not understand what you mean here. > I also doubt if I use hypre correctly for this case. Is there anyway to > check this problem, or is it possible to increase the factorization level > through hypre? > > I don't know. Matt > Thanks, > > Danyang > > On 17-05-24 04:59 AM, Matthew Knepley wrote: > > On Wed, May 24, 2017 at 2:21 AM, Danyang Su <[email protected]> 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. 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? >> > > We have ILU(k) supported in serial. However ILU(dt) which takes a > tolerance only works through Hypre > > http://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html > > I recommend you try SuperLU or MUMPS, which can both be downloaded > automatically by configure, and > do a full sparse LU. > > Thanks, > > Matt > > >> Thanks and regards, >> >> Danyang >> >> >> > > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener > > http://www.caam.rice.edu/~mk51/ > > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener http://www.caam.rice.edu/~mk51/
