[Users] Definitions of different reductions in CarpetIOScalar

[Roland Haas]

Hello Shamim Haque,

Gald to have been able to help.

Yours,
Roland

> Hello Roland,
> 
> This helps. Thanks a lot.
> 
> Regards
> Shamim Haque
> Senior Research Fellow (SRF)
> Department of Physics
> IISER Bhopal
> 
> ᐧ
> 
> On Fri, Mar 8, 2024 at 9:14 PM Roland Haas <rhaas at illinois.edu> wrote:
> 
> > Hello Shamin,
> >  
> > > CarpetIOScalar thorn has the following options from outscalar_reductions:
> > >
> > > count minimum maximum sum average norm1 norm2 norm_inf icount iaverage
> > > inorm1 inorm2
> > >
> > > What are the expressions/definitions for each? I could not find them in  
> > the  
> > > ETK documentation. Please help.  
> >
> > They are defined by CarpetReduce
> > (https://urldefense.com/v3/__https://bitbucket.org/eschnett/carpet/src/master/CarpetReduce/__;!!DZ3fjg!95Yy0JllwSa-J8mctaaso3iAcNHMeKjuSqSbCXMcaJzSr__dMzz4tMv2Yb93afgIZAm_Q9w2wySfEofrMDEx$ ) and
> > mostly match the corresponding ones in LocalReduce (which has docs):
> >
> >
> > https://urldefense.com/v3/__http://einsteintoolkit.org/thornguide/CactusNumerical/LocalReduce/documentation.html__;!!DZ3fjg!95Yy0JllwSa-J8mctaaso3iAcNHMeKjuSqSbCXMcaJzSr__dMzz4tMv2Yb93afgIZAm_Q9w2wySfEkzMOFTP$ 
> >
> > The difference between the "i" and non "i" flavors is that the regular
> > ones weigh the influence of a grid point by the volume of its cell so
> > that eg the "sum" reduction becomes (up to a constant factor of the
> > cell volume on the coarsest grid) the Riemann sum (integral) of the
> > data.
> >
> > The "i" ones leave out that factor so just sum up the values.
> >
> > For reductions that do not perform sums (min/max) I don't think there
> > is is a difference between the two.
> >
> > Yours,
> > Roland
> >
> > --
> > My email is as private as my paper mail. I therefore support encrypting
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> >  


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