Hi Fabrice,
Recently, I posted the following example:
void fit2d()
{
//example illustrating how to fit a 2-d histogram of type y=f(x)
const Int_t n = 6;
Float_t x[n] = {0.092,0.83,0.94,0.81,0.12,0.1};
Float_t y[n] = {0.71,9.4,9,8,0.3,0.71};
TCutG *cut = new TCutG("cut",n,x,y);
TH2F *h2 = new TH2F("h2","h2",40,0,1,40,0,10);
Float_t u,v;
for (Int_t i=0;i<100000;i++) {
u = gRandom->Rndm();
v = 10*gRandom->Rndm();
if (cut->IsInside(u,v)) h2->Fill(u,v);
}
TCanvas *c1 = new TCanvas("c1","show profile",600,900);
c1->Divide(1,2);
c1->cd(1);
h2->Draw();
c1->cd(2);
TProfile *prof = h2->ProfileX();
prof->Fit("pol1");
}
Rene Brun
Fabrice Podlyski wrote:
>
> Hello,
>
> I try to do a linear fit (ax+b) in a 2d histogram.
> In fact, i just want "regression line".
> I have searched in the Tutorial examples, but i 've
> found more complicated examples !
> (I try to update the myfit2.C program to my case by replacing
> the fitf function but without success !)
>
> Is it possible to do that ?
>
> Thank you in advance for your help,
>
> regards
>
> FP
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