Hi Alessio,
TF1::GetHistogram returns a pointer to the internal TH1 object used to
draw the function. This object is only created when you paint the TF1.
If you want to map a TF1 to a TH1, do, eg:
root > TF1 *f1 = new TF1("f1","sin(x)/x",0,10);
root > TH1F h("h","",100,0,10);
root > h.Eval(f1);
Rene Brun
Alessio PICCIOLI wrote:
>
> How can i use TF1::GetHistogram() without drawing the function (using
> TF1::Draw()) ?
>
> If i do not use draw() i get the following error:
>
> root [13] TF1 *func = new TF1 ( "func" , "x" , 0 , 1 ) ;
> root [14] TH1D *histo = func -> GetHistogram ( ) ;
> root [15] histo -> Draw ( ) ;
> Error: illegal pointer to class object histo 0x0 148 FILE:(tmpfile) LINE:1
> *** Interpreter error recovered ***
>
> Alessio
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