[Carpet] weight is initialised differently with use_grid_structure_from_checkpoint feature turned on

[Erik Schnetter]

On Feb 21, 2007, at 08:04:09, Thomas Radke wrote:

> Hi,
>
> various people had reported the problem of norm output being  
> slightly different after recovery compared with the values from the  
> original checkpoint run. Bruno created the attached WaveToy  
> parameter file which can be used to easily reproduce the problem.
>
> I found that this happens only if  
> IOHDF5::use_grid_structure_from_checkpoint is turned on, and buffer  
> zones are being used. Disabling this feature does produce exactly  
> the same values for all norms.
>
> Luckily the problem doesn't seem to be in the recovery code or in  
> the Carpet scheduler, affecting the entire evolution. In addition  
> to the norms, I also compared the full phi function as 3D ASCII  
> data and found it to be bitwise-identical. This indicates that the  
> problem is related to the calculation of the norms only. Indeed,  
> comparing the weight function in 3D ASCII does show differences in  
> the buffer zones. Somehow the weight is initialised differently  
> after recovery.
>
> Is that enough information for you, Erik, to fix the problem ?

I looked at this problem yesterday, and I think I corrected it  
yesterday with a patch to the development version.  The problem was  
indeed that the weights which are used for reduction operations were  
not initialised correctly.

My patch changed things to that, after recovery, the postregrid bin  
is run for all time levels.  This should initialise the weight (and  
all other such grid functions with time levels) correctly.  I checked  
with Bruno's parameter file, and it works now correctly for me.

I asked Bruno to check whether this solves his problem.  Is there is  
a problem left over which I did not catch?

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>

My email is as private as my paper mail.  I therefore support encrypting
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