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

[Gideon Simpson]

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

-gideon

> 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 <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

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