Ok... I had a problem with indexing (-1 offset) in the local to global mapping and now I get the following:
Testing hand-coded Jacobian, if the ratio is O(1.e-8), the hand-coded Jacobian is probably correct. Run with -snes_test_display to show difference of hand-coded and finite difference Jacobian. Norm of matrix ratio 3.24883e-07 difference 3.24883e-05 Norm of matrix ratio 3.25662e-07 difference 3.25662e-05 Norm of matrix ratio 3.26517e-07 difference 3.26517e-05 [0]PETSC ERROR: SNESSolve() line 2255 in src/snes/interface/snes.c so I guess this means that it is slightly wrong :) can you explain now what it is doing here (and why I get this error)... can I make it try to solve the equation with the approximated fd jacobian (is it doing that already?)
