Does this look good: Norm of matrix ratio 2.19793e-09, difference 2.14739e-07 (user-defined state) Norm of matrix ratio 1.10356e-08, difference 1.07917e-06 (constant state -1.0) Norm of matrix ratio 1.15084e-08, difference 1.12541e-06 (constant state 1.0)
On Thu, Aug 17, 2017 at 12:44 AM, Mark Adams <[email protected]> wrote: > I see, I had a tiny time step that make the Jacobian big and the errors > small. > > On Thu, Aug 17, 2017 at 12:30 AM, Mark Adams <[email protected]> wrote: > >> >> >> On Thu, Aug 17, 2017 at 12:22 AM, Matthew Knepley <[email protected]> >> wrote: >> >>> On Wed, Aug 16, 2017 at 10:14 AM, Mark Adams <[email protected]> wrote: >>> >>>> I just want to check the interpretation of snes_type test. Is this >>>> pretty conclusively good? >>>> >>> >>> It looks right, but the entires in the Jacobian are crazy. You should >>> non-dimensionalize first. >>> >> >> This is non-dimensionalize and it is 2D FE 2nd order equation so >> everything should be O(1), that is, there is no 1/h like term. And the >> domain is (1) and the grid is small so h is O(1) anyway. >> >> >>> >>> Matt >>> >>> >>>> 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 1.38299e-16, difference 1.11738 (user-defined >>>> state) >>>> Norm of matrix ratio 9.50529e-09, difference 7.67972e+07 (constant >>>> state -1.0) >>>> Norm of matrix ratio 1.07438e-08, difference 8.68036e+07 (constant >>>> state 1.0) >>>> >>>> >>> >>> >>> -- >>> 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 >>> >>> http://www.caam.rice.edu/~mk51/ >>> >> >> >
