I am using PETSc's nonlinear solver package SNES to solve a system of nonlinear equations obtained by discretizing a partial differential equation. How can I determine why the solver is not converging and what can I do to successfully solve my equations?
Newton's method may not converge for many reasons, here are some of the most common.
Here are some of the ways to help debug lack of convergence of Newton.
Here are some ways to help the Newton process if everything above checks out