Re: Wigner D-function in ROOT or C++?

From: Arthur E. Snyder <snyder_at_slac.stanford.edu>
Date: Mon, 3 Jul 2006 10:20:19 -0700 (PDT)


Hi Rene,

I'm not looking for Breit-Wigner but for Wigner's so called D-function (D(alpha,beta,gamma)) which are functions of anlges used in partial wave analysis based on the Jacob and Wick formalism.

The article I refer to proposes somekind of mathlib to collect in C++ form a lot of mathmatical functions available dispersed among a lot libraries of functions like cernlib, clhep, napl, and so forth. The D-functions are just mentioned in one of the tables .. google hunted them out .. with a search for "Wigner D-function C++".

Anyway I need the D-function in a form I can access from ROOT. I may just have to code the few lower order ones I need myself, but I'd rather have a nice (well debugged) set from some package or class library.

-Art S.

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On Mon, 3 Jul 2006, Rene Brun wrote:

> Art,
>
> I am curious to know the talk/article you are referring to ::)
> In ROOT we have the Breit-Wigner distributtion. See
> http://root.cern.ch/root/htmldoc/src/TMath.cxx.html#TMath:BreitWigner
> http://root.cern.ch/root/htmldoc/src/TRandom.cxx.html#TRandom:BreitWigner
>
> see also:
> http://root.cern.ch/root/roottalk/roottalk05/0954.html
>
> Rene Brun
>
> Snyder, Arthur E. wrote:
> > Does anybody know where to find a implentation of Wigner D-functions that I can use in ROOT?
> >
> > I found a talk/article by Rene where they are mentioned but the implentation seems to be in
> > the future.
> >
> > -Art S.
> >
> >
> > -----Original Message-----
> > From: owner-roottalk_at_pcroot.cern.ch on behalf of Fine, Valeri
> > Sent: Sun 7/2/2006 6:56 PM
> > To: nasim; roottalk_at_pcroot.cern.ch
> > Subject: RE: [ROOT] geting the values stored in the histograms.
> >
> >
> > You need either
> > http://root.cern.ch/root/htmldoc/TH1.html#TH1:GetBinLowEdge
> > or
> > http://root.cern.ch/root/htmldoc/TH1.html#TH1:GetBinCenter
> >
> > Valeri
> >
> >> There are two ways:
> >>
> >> 1. Each concrete histogram class is derived from TArray class
> >> http://root.cern.ch/root/htmldoc/TH1F.html
> >> This means one can treat each histogram object as a plain array of
> >> "float" number and use it as such. (For example method "[int]} returns
> >> what you want)
> >>
> >> TH1F *histogram = new TH1F( some parameters);
> >> TH1F &bins = *histogram;
> >> for (int i=0; i< 100; i++)
> >> printf(" Bin %i contains the value %f\n", i, bins[i]);
> >>
> >> 2. One can use the methods like TH1::GetBin<XXX>
> >> , where XXX could be "Center", "Content", "Error" etc
> >> see doc please
> >> http://root.cern.ch/root/htmldoc/TH1.html#TH1:GetBinContent
> >>
> >>
> >
> >
> >
> >> Hope this helps.
> >>
> >> ----
> >> Best regards
> >> Valeri
> >>
> >>
> >>
> >>> -----Original Message-----
> >>> From: owner-roottalk_at_pcroot.cern.ch
> >>>
> >> [mailto:owner-roottalk_at_pcroot.cern.ch] On
> >>
> >>> Behalf Of nasim
> >>> Sent: Sunday, July 02, 2006 7:43 PM
> >>> To: roottalk_at_pcroot.cern.ch
> >>> Subject: [ROOT] geting the values stored in the histograms.
> >>>
> >>>
> >>> Hi,
> >>> If we have one dimensional histogram with 100 entries.
> >>> Is it possible to extract the value of its x axis for each entry?
> >>>
> >>> Any help would be appreciated,
> >>>
> >>> Nasim
> >>>
> >>>
> >>> --
> >>>
> >
> >
> >
> >
> >
> >
> >
>
>
Received on Mon Jul 03 2006 - 19:20:31 MEST

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