ex19 comes to mind, though it's a bit overkill for what you're doing... http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/src/snes/examples/tutorials/ex19.c.html
ex19 uses DAs and DMMG, which is kind of like a meta-DA for using multigrid-style solvers. Both work well with structured grids. You may also want to review the PETSc manual section on DA. A On Tue, Aug 18, 2009 at 3:30 AM, nicolas aunai <nicolas.aunai at gmail.com>wrote: > Dear all, > > > I have a simulation code (particle in cell) in which I have to solve a > linear vector equation 4 times per time step. A typical run consists > of 50 000 time steps. The grid is rectangular and uniform of size Lx, > Ly, with nx+1 and ny+1 points in the x and y direction respectively., > (nx, ny) could be at max (1024,1024). > > The vector equation is the following : > > B(x,y) - a*Laplacian(B(x,y)) = S(x,y) > > > Where B and S are 2D vector fields with 3 components (Bx, By, Bz and > Sx, Sy, Sz), each depending on the x and y coordinates. > > > 'a' is a positive constant, smaller than one, typically a= 0.02 > > Boundary conditions may depend on for which B component we are solving > the equation. On the x=cst borders, the boundary is always periodic, > no matter what component is solved, but on y=cst borders, the boundary > condition can be either Neumann or Dirichlet. > > So far, I have written a small code that creates a vector solution, a > vector RHS and the matrix operator, and solve a scalar equation of > this type. Solving my vector equation would then just call 3 times > this kind of code... but I believe there is another way to deal with > vector fields and linear systems with Petsc, using DAs no ? Could > someone explain me how solve this the proper way and/or show me some > code solving linear system with vector fields ? (is there an example > in the exercices that I would not have seen ?) > > > > Thanks a lot > Nico > -- Aron Jamil Ahmadia Assistant Research Scientist King Abdullah University of Science and Technology -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20090818/1cb39e96/attachment.htm>
