On Thu, Oct 3, 2013 at 8:04 AM, mary sweat <mary.swea...@yahoo.it> wrote:
> Hi all > I am very new to petsc and to c programming. I need to build a huge sparse > matrix with a block structure. > The problem is that my matrx may be huge (200000*200000) so i Need a way > to define it through the kronecker product or memorizing just the > overdiagonal, diagonal and subdiagonal block. > Is it possible in petsc? any suggestions? > thanks a million in advance > This is the 2D Laplacian with a 5-point FD stencil. There are many PETSc examples which form and solve this. For example, here is an example: 1,640,961 unknowns (on the fine level) 8,199,681 nonzeros ./ex5 -da_grid_x 21 -da_grid_y 21 -da_refine 6 -ksp_rtol 1.0e-9 -pc_type mg -pc_mg_levels 4 -snes_monitor -snes_view This takes 375s on my underpowered Mac Air laptop. Thanks, Matt -- 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