Hi Dan,
If you are using recent ROOT you can use TMath::Poisson function in
TFormula. And for factorial you can use TMath::Gamma function, e.g.
TFormula factorial("factorial","TMath::Gamma(x+1)");
factorial.Eval(10)
(Double_t)3.62880000000318652e+06
or to define Poisson PDF:
TF1 poiss("poiss","[0]*TMath::Poisson(x,[1])",0,5);
poiss.SetParameter(0,1);
poiss.SetParameter(1,1);
poiss.Draw()
Best regards,
Stanislav.
On Wed, 5 Nov 2003, Dan Holmes wrote:
> Hello,
>
> my problem for today is that i would like to define a TFormula with a
> factorial in it (poisson distribution) with the aim of being able
> to evaluate and integrate it at non-integer points..
>
> i have a bit of c++ code that works out factorials but i want to be able
> to define the formula and plot it as a function..
>
> do you have any examples of this?
>
> cheers,
>
> Dan.
>
>
>
>
>
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