[Users] Definitions of different reductions in CarpetIOScalar

[Shamim Haque 1910511]

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://bitbucket.org/eschnett/carpet/src/master/CarpetReduce/) and
> mostly match the corresponding ones in LocalReduce (which has docs):
>
>
> http://einsteintoolkit.org/thornguide/CactusNumerical/LocalReduce/documentation.html
>
> 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
>
> --
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