Hello Matt, Ah ok. I had tried specifying -pc_mg_levels earlier, but it asks for interpolation to be setup. I am currently working on using DMDA from examples 32 and 34, which sets up the interpolation, using DMDASetInterpolationType. So this is the recommended way to go forward right?
Since I supply the sparse matrix format and the rhs values to PETSc, does it make sense to do a DMDACreate1d instead of 3d? I did a sample implementation using DMDA 1d and when I call KSPSolve and fetch the solution, it comes out all zeros, with the solver having converged. I am trying to understand what I am doing wrong there. On Mon, Oct 12, 2015 at 10:17 PM, Matthew Knepley <[email protected]> wrote: > On Mon, Oct 12, 2015 at 9:11 PM, K. N. Ramachandran <[email protected]> > wrote: > >> Hello Matt, >> >> Actually I felt the boundary conditions were having a role to play and >> set all the boundary conditions to Dirichlet. In this case, convergence was >> almost immediate with the Hypre preconditioner, taking 17 seconds with 3 >> iterations. The MG method took about the same time though. >> >> So I reverted to the Dirichlet, Neumann mix of BCs and Hypre starts to >> diverge. Please find attached the output for the Hypre run using Dirichlet >> and Neumann for a 21^3 grid (rows), with a max of 7 nonzeros per row. >> Details of the options used before running are in the file. The solver used >> in all cases is bcgs. >> >> Also attached is the MG output for 101^3 grid >> 1) Dirichlet and Neumann >> 2) Dirichlet only >> >> where it seems to take about the same time. >> > > Notice that you have no levels of MG here. You need to use -pc_mg_levels > <n> > > Matt > > >> >> Thanking You, Ramachandran K.N. Ph: 814-441-4279
