Re: Gamma function

From: Rene Brun <Rene.Brun_at_cern.ch>
Date: Fri, 3 Mar 2006 19:18:32 +0100 (MET)


Use

   ROOT::Math::conf_hyperg(1,2,x)
instead of

   ROOT::TMath::conf_hyperg(1,2,x)

Rene Brun

On Fri, 3 Mar 2006, George Japaridze
wrote:

> Hi,
> I'm getting the same while trying to plot incomplete gamma - just the
> straight line (ROOT v 5.08/00).
>
> And, I see another problem with the confluent hypergeometric function:
>
> 1) ROOT calculates it's OK (I have LibmathMore loaded):
> ----------------------------------------------------------
> root [8] ROOT::Math::conf_hyperg(1,2,3)
> (double)6.36184564106255568e+00
> _________________________________
>
> But, when I try to define the function I want to plot, that's the error
> message:
> ________________________________________________________________________________
> root [7] TF1 *f3 = new TF1("f3","ROOT::TMath::conf_hyperg(1,2,x)",0,10);
> Error in <TFormula::Compile>: Bad numerical expression :
> "ROOT::TMath::conf_hyperg(1,2,x)"
> Error in <TF1::TF1>: function: f3/ROOT::TMath::conf_hyperg(1,2,x) has 0
> parameters instead of 1
> _________________________________________________________________________________
>
> i.e. in distinct the with incomplete gamma function, I can not even define
> the confluent hypergeometric function.
>
> Need to use gsl functionality (special functions) included in ROOT.
>
> What am I doing wrong?
>
> Thanks,
>
> George
>
>
> PS. It would help greatly if syntax gets unified. E.g I can calculate
> incomplete gamma using both
> root [0] TMath::Gamma(1,2)
> and
> root [1] ROOT::TMath::Gamma(1,2)
>
> but only
> ROOT::Math::conf_hyperg(1,2,3)
>
> works for calculating the value of confluent hypergeometric.
>
> On Mar 2, 2006, at 3:53 PM, Benjamin-Alejandro Morales-Ruiz wrote:
>
>> TF1 *g1 = new TF1("g1","TMath::Gamma(1,x)",0,10);
>
>
>
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>
>
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>
>
> *******************************************************************************************
> Dr. George Japaridze CTSPS, Clark Atlanta
> University
>
> japar_at_ctsps.cau.edu 404 880 6420 Office
> http://ctsps.cau.edu/george/index.html 404 226 3847 Cell
>
>
>
>
>
Received on Fri Mar 03 2006 - 19:19:33 MET

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