Checking the Jacobian, this is a pretty standard output:
Testing hand-coded Jacobian, if the ratio is O(1.e-8), the hand-coded
Jacobian is probably correct.
Finite difference Jacobian
Hand-coded Jacobian
Hand-coded minus finite difference Jacobian
6.08281e-10 = ||J - Jfd||//J|| 0.000151055 = ||J - Jfd||
Things look favorable in terms of relative difference, but the absolute
difference is a bit more suspect.
-gideon
> On Sep 8, 2015, at 11:49 PM, Barry Smith <[email protected]> wrote:
>
>>
>> On Sep 8, 2015, at 10:28 PM, Gideon Simpson <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> I should clarify, in that run, I ran with the analytic jacobian, but I did
>> not use -snes_mf_operator. If I use that flag, the performance is a bit
>> different. In particular, the true residual norms are not as good. How
>> should I interpret that?
>
> The "analytic Jacobians" are wrong. Of course, that is easy to say, the hard
> part is figuring out exactly what entries are wrong.
>
> You can try the following options. They are experimental so may be flaky run
> with the options below (but not -snes_fd or -snes_mf_operators)
>
> -snes_check_jacobian
> -snes_check_jacobian_view
>
