Run the example /petsc/src/snes/examples/tutorials/ex28.c using the following options(found in the makefile)
./ex28 -da_grid_x 20 -snes_converged_reason -snes_monitor_short -problem_type 2 It works using default analytic Jacobian to solve coupled system, however, I comment Line 434 : ierr = SNESSetJacobian(snes,B,B,FormJacobian_All,user);CHKERRQ(ierr); and run the code again using the same options (i.e., FD Jacobian instead of analytic Jacobian), we will get the results: Nonlinear solve did not converge due to DIVERGED_MAX_IT iterations 50 Could you explain why it does not work using FD Jacobian in this example? Thanks -- ------------------------------ This message and its contents, including attachments are intended solely for the original recipient. If you are not the intended recipient or have received this message in error, please notify me immediately and delete this message from your computer system. Any unauthorized use or distribution is prohibited. Please consider the environment before printing this email.
