On Wed, Sep 28, 2022 at 2:27 PM wangzj997 <wangzj...@foxmail.com> wrote:
> 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 > How do you know it is positive definite? This is unusual when you have 0 on the diagonal. Preconditioners depend sensitively on the matrix properties. Is this a discretization of some operator? Thanks, Matt > 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. > > > > -- 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 https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>