Re: formula with multiple TFormula

From: Rene Brun (Rene.Brun@cern.ch)
Date: Mon Dec 07 1998 - 16:34:29 MET


"T Auger
> 
> Hi ROOTers,
> I would like to draw formula using user defined basic
> formula (defined with TFormula).
> 
> e.g :
> 
> pomeron = new TFormula("pomeron","[0]*pow((x-0.939*0.939)/1.878,[1])");
> f = new TFormula("f","([2]*pow((x-0.939*0.939)/1.878,[3]))");
> 
> total = new TF1("total","pomeron+f",1,20);
> or
> total = new TFormula("total","pomeron+f");
> 
> but I cannot combine "pomeron" and "f" ( the call above misfortunely
> don't add up to give me the sum). I could do it by writing them
> down as a whole but I figure it would be nice if one could combine
> TFormula to obtain new ones. Is this possible?
> 

Hi Thierry,
I have no problems executing your macro. I have made slight changes
to show two functions on the same graph.
A similar example is given in tutorials/fillrandom.C
I assume you run with 2.00/13 or 2.20.

Rene Brun

{
   gROOT->Reset();
   TFormula *pomeron = new
TFormula("pomeron","[0]*pow((x-0.939*0.939)/1.878,[1])");
   TFormula *f = new
TFormula("f","([2]*pow((x-0.939*0.939)/1.878,[3]))");
   TF1 *total = new TF1("total","pomeron + f",1,20);
   total->SetParameters(1,2,1.5,2.4);
   total->Draw();
   TF1 *one = new TF1("one","pomeron",1,20);
   one->SetParameters(1,2,1.5);
   one->Draw("same");
}



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