Hello, I am working to solve a linear system of equations using a KSP solver. The size of the matrix is approximately ~370,000. The following settings have been used to set up the solver"
[image: Inline image 1] The L2 norm of the RHS for this problem is ~365, which has been calculated using the subroutine *VecNorm*. When I solve this system, I am finding that irrespective of the number of maximum iterations the L2 norm of final residual is pretty much constant around ~37860. The L2 norm of the residual has been found using the subroutine *KSPGetResidualNorm. *The following is how the residual is varying for different maximum iterations. *[image: Inline image 2]* With such being the case, I have the following doubts to clarify: - Are the settings used by me for the KSP solver adequate enough? Or am I missing something? - What could be reasons for my KSP solver to not converge below the permissible tolerance? - For a linear system of given size, how can one determine the number of maximum iterations that should be set for the KSP solver? Is there a thumb rule? Regards, Rachit Prasad
