[LORENE] regarding to the definition of shift vector in Bin_NS

Jian Tao jtao at artsci.wustl.edu
Thu Dec 9 23:07:54 CET 2004

>Do I understand correctely that you do not have
>any trouble with irrotational data, but only
>with corotating data ?


In the irrotational case The residue of the constraint equations converges
to the 2nd order to zero when I increased the resolution.
However, in the corotational case, the Momentum constraint doesn't converge
at all, though the Hamiltonian constraint seems to converge to some big value.  

>I will have again a look about the sign convention
>of the shift vector (I've just discussed this with
>Lap-Ming. I guess he will write you).

The constraint problem is a seperate issue since the shift vector should not
affect the constraints at all. I noticed the sigh difference in the 3+1 formalism
when I read your paper for the first time and considered that when I began to 
use Meudon datasets.


>    Eric.
>Jian Tao wrote:
>>Dear Eric,
>>On Thursday 09 December 2004 02:43 am, you wrote:
>>>Actually I've corrected these comments after
>>>your first remark about this.
>>>I think everything is correct now.
>>>By the way, can you tell me which data set
>>>you are using exactely. Some data sets may
>>>be better than others (this is why I am
>>Currently I am using the following two datasets to test things out and 
>>compare against Luca Baiotti's results.
>>Dataset #1: G2_I14vs14_D4R33_45km 
>>Dataset #2: G2_C14vs14_D4R33_45km
>>I calculated both Ham and Mom constraints of both datasets. You can 
>>have a look at the results at 
>>1. Irrotation: 
>>FILE NAME:  Ir_HAM.ps Ir_MOMY.ps         
>>   All the constraints calculated at a resolution 
>>higher than 50^3 are scaled to the 2nd order. 
>>e.g. when the number of grid points is 75, I timed (75/50)^2 to the
>>All the constraints converge to the 2nd order as I expect. 
>>It is good !
>>2. Corotation:
>>FILE NAME:  Cr_HAM.ps Cr_MOMY.ps              
>>  All the constraints are plotted directly from the output files. 
>>It seems the Hamiltonian converges to some value, which is much bigger
>>than, what you suggested in your previous email, 10^-5
>>The momentum(momy along x axis) constraint doesn't converge 
>>at all. I got this result after I did a fresh CVS checkout from Lorene
>>CVS server. However,  the old Lorene code(before you fixed the bug)
>>gives converging momentum constraints, but they also converged to
>>some big values.  
>>Considering various tests have been done to verify the integrity of Meudon
>>datasets in numerous papers,  I doubt the thought that this kind of tests have
>> never been done before.  I will be glad to know what you got.
>>Lorene.list mailing list
>>Lorene.list at obspm.fr
>Eric Gourgoulhon
>Laboratoire de l'Univers et de ses THeories (LUTH)
>UMR 8102 du CNRS / Observatoire de Paris, F-92195 Meudon Cedex, France
>tel: +33 1 45 07 74 33 (secretariat : +33 1 45 07 75 10)
>e-mail: eric.gourgoulhon/at/obspm.fr    WWW: http://www.luth.obspm.fr/

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