[petsc-users] conditioning of snes with dmcomposite & grid sequencing

[Barry Smith]

> On Sep 11, 2015, at 4:30 PM, Gideon Simpson <gideon.simpson at gmail.com> wrote:
> 
> Are there any built in routines for freezing variables in SNES, or will that need to be handled by hand.
> 
> Also, I remain curious about the starting guess that the grid sequence uses during each refinement.  Is there a way to dump those to disk for inspection?
  
  Not really. You can look in SNESSolve() and see where the interpolation takes place and add your own call to VecView() to save the result.

  Barry

> 
> -gideon
> 
>> On Sep 11, 2015, at 4:05 PM, Matthew Knepley <knepley at gmail.com> wrote:
>> 
>> On Fri, Sep 11, 2015 at 1:05 PM, Gideon Simpson <gideon.simpson at gmail.com> wrote:
>> Since the problem has not only the two components in the DM, but the second component has 4 degrees of freedom per mesh point, I thought it best to do the post processing separately.  See attached
>> 
>> So the whole thing is being controlled by 1 variable.
>> 
>> We should try freezing everything else, and just solving that scalar equation I guess.
>> 
>>    Matt
>>  
>> -gideon
>> <Screen Shot 2015-09-11 at 2.04.25 PM.png>
>>> On Sep 11, 2015, at 10:16 AM, Matthew Knepley <knepley at gmail.com> wrote:
>>> 
>>> On Fri, Sep 11, 2015 at 9:08 AM, Gideon Simpson <gideon.simpson at gmail.com> wrote:
>>> Following up on the previous thread, for my dm composite problem, I find that at the end of the first grid sequence,where it fails to converge, the distribution of the norms between the two pieces are:
>>> 
>>>  39 SNES Function norm 2.253098577796e+02 
>>>  40 SNES Function norm 2.253098577331e+02 
>>>  41 SNES Function norm 2.253098577228e+02 
>>>  42 SNES Function norm 2.253098577212e+02 
>>>  43 SNES Function norm 2.253098577174e+02 
>>>  44 SNES Function norm 2.253098577166e+02 
>>>  45 SNES Function norm 2.253098577158e+02 
>>>  46 SNES Function norm 2.253098577157e+02 
>>>  47 SNES Function norm 2.253098577156e+02 
>>>  48 SNES Function norm 2.253098577156e+02 
>>> Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 48
>>>  ||r|| = 225.31, 7999 entries
>>>  ||rp|| = 140.021, 3 entries
>>>  ||rQ|| = 176.518, 7996 entries
>>> 
>>> Since I think we were convinced that this was intrinsic to the problem, and not a function of the Jacobian function, I am using my Jacobian.
>>> 
>>> Okay, I see no pattern in the fields. Lets plot these 2 vectors, -vec_view draw, and screenshot.
>>> 
>>>   Matt
>>>  
>>> -gideon
>>> 
>>> 
>>> 
>>> -- 
>>> 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
>