[petsc-users] checking jacobian

[Matthew Knepley]

On Tue, Aug 11, 2015 at 1:09 PM, Gideon Simpson <gideon.simpson at gmail.com>
wrote:

> I don’t see it listed in -help, but I do get
>
> ./blowup -xmax 50 -nx 1000 -snes_check_jacobian
>       Testing hand-coded Jacobian, if the ratio is O(1.e-8), the
> hand-coded Jacobian is probably correct.
>       Run with -snes_check_jacobian_view [viewer][:filename][:format] to
> show difference of hand-coded and finite difference Jacobian.
>     63386.1 = ||J - Jfd||//J|| 63386.1  = ||J - Jfd||
>

It must be broken in 3.5.3 for some reason. I would use the latest release.

   Matt


> -gideon
>
> On Aug 11, 2015, at 2:07 PM, Matthew Knepley <knepley at gmail.com> wrote:
>
> On Tue, Aug 11, 2015 at 1:04 PM, Gideon Simpson <gideon.simpson at gmail.com>
> wrote:
>
>> Macports installation of 3.5.3.
>>
>
> Use -help to find the option name. Maybe its -snes_test.
>
>   Thanks,
>
>     Matt
>
>
>> -gideon
>>
>> On Aug 11, 2015, at 2:03 PM, Matthew Knepley <knepley at gmail.com> wrote:
>>
>> On Tue, Aug 11, 2015 at 12:51 PM, Gideon Simpson <
>> gideon.simpson at gmail.com> wrote:
>>
>>> #End of PETSc Option Table entries
>>> There is one unused database option. It is:
>>> Option left: name:-snes_check_jacobian_view (no value)
>>>
>>
>> This is the option for the newest release. What are you using?
>>
>>    Matt
>>
>>
>>> -gideon
>>>
>>> On Aug 11, 2015, at 1:50 PM, Matthew Knepley <knepley at gmail.com> wrote:
>>>
>>> On Tue, Aug 11, 2015 at 12:49 PM, Gideon Simpson <
>>> gideon.simpson at gmail.com> wrote:
>>>
>>>> Maybe it’s a quirk of the macports installation of petsc, but nothing
>>>> seems to be getting generated.
>>>>
>>>
>>> Run with -options_left. Is it reading the option?
>>>
>>>   Matt
>>>
>>>
>>>> -gideon
>>>>
>>>> On Aug 11, 2015, at 1:40 PM, Jed Brown <jed at jedbrown.org> wrote:
>>>>
>>>> Gideon Simpson <gideon.simpson at gmail.com> writes:
>>>>
>>>> I’m a bit confused by the following options:
>>>>
>>>> Run with -snes_check_jacobian_view [viewer][:filename][:format] to show
>>>> difference of hand-coded and finite difference Jacobian.
>>>>
>>>> What flags do I pass it to get some output to diagnose my Jacobian
>>>> error?
>>>>
>>>>
>>>> Nothing to display ASCII to the screen.  You might use
>>>> "binary:thematrix" if you want to read it in with Python or MATLAB, for
>>>> example.
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> 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
>>>
>>>
>>>
>>
>>
>> --
>> 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
>>
>>
>>
>
>
> --
> 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
>
>
>


-- 
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
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