Dear PETSc development team?? Currently, I am learning and trying to use PETSc's KSP to solve large-scale sparse linear systems Ax= b, where A is symmetric positive definite and nonsingular. However, the main diagonal of A contains many 0 items, which leads to the fact that many preconditioners cannot be used when using MPI for multi-process solution, and the number of iterations is large, and the convergence is slow. May I ask how to solve this problem? If it is necessary to make the main diagonal of A all non-zero items, is there any solution in PETSc?
I would be grateful if you would reply and answer my question. Best Regards.
