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

[Gideon Simpson]

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?

-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 <mailto: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 <mailto:knepley at gmail.com>> wrote:
>> 
>> On Fri, Sep 11, 2015 at 9:08 AM, Gideon Simpson <gideon.simpson at gmail.com <mailto: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

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