[petsc-users] checking jacobian

[Gideon Simpson]

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||

-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 <mailto: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 <mailto:knepley at gmail.com>> wrote:
>> 
>> On Tue, Aug 11, 2015 at 12:51 PM, Gideon Simpson <gideon.simpson at gmail.com <mailto: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 <mailto:knepley at gmail.com>> wrote:
>>> 
>>> On Tue, Aug 11, 2015 at 12:49 PM, Gideon Simpson <gideon.simpson at gmail.com <mailto: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 <mailto:jed at jedbrown.org>> wrote:
>>>> 
>>>> Gideon Simpson <gideon.simpson at gmail.com <mailto: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

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