Hi I am new to petsc and am attempting to parallelize ex13.c (Poisson example) in the ksp tutorials. I have been able to write some simple test codes and get them to work correctly and learn some of the mechanics of what petsc is doing, with respect to creating mpi vectors and matrices and in using the DA functions. I attempting to test the different solvers I am having some trouble... When I try to run with the same solver it fails with a message about Matrix format for mpiaij does not have a built-in PETSc direct solver. Which solvers are available for mpiaij formats? Also I created the Matrix and Vectors using the DACreate2d(dA,PETSC_COMM_WORLD,..... DAGetMatrix(dA,MATMPIAIJ,&A) DACreateGlobalVector(dA,&x) DACreateGlobalVector(dA,&b) .... is this dictating the types of solvers available? Is there another example of the variable Poisson in Parallel? or creating in a variable RHS and the rho variable in ex13 that maps from local to global indices? Thanks Chris Bording