Re: Gamma function

From: George Japaridze <>
Date: Fri, 3 Mar 2006 12:55:11 -0500

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?



PS. It would help greatly if syntax gets unified. E.g I can calculate incomplete gamma using both
root [0] TMath::Gamma(1,2)
root [1] ROOT::TMath::Gamma(1,2)

but only

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);

Dr. George Japaridze                                    CTSPS, Clark  
Atlanta University                                    404 880 6420  
Office           404 226 3847 Cell
Received on Fri Mar 03 2006 - 18:55:27 MET

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