Hi Mikhail,
Nested function calls are not allowed in the TF1 constructor that you are using.
You should write a small interpreted or compiled function with this kind
of statements and use the corresponding TF1 constructor.
Example:
Double_t pow2(Double_t *x, Double_t *par)
{
Double_t xx = x[0];
return TMath::Power(TMath::Power(xx,2),2);
}
void powpow()
{
TCanvas *c1 = new TCanvas("c1","the fit canvas",500,400);
TF1 *pow2 = new TF1("pow2",pow2,-2,2,0);
pow2->Draw();
}
Rene Brun
Mikhail Jabitski (Zhabitsky) wrote:
>
> Dear ROOT'ers!
>
> It looks that TF1 doesn't analyze properly expressions with nested calls of
> pow():
>
> root [0] TF1 *f = new TF1("f","pow(pow(x,2.0),2.0)")
>
> *ERROR 22 :
> POW requires two arguments
> root [1]
>
> Best regards,
> Mikhail
>
> PS
> I use ROOT 2.25/03
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