Eiko, Cynthia,
You will find below a simple example using a profile histogram
as suggested by Petar. The example uses a straight line fit.
You can change it to any type of function according to the shape
of your 2-d distribution.
Rene Brun
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");
}
Shin-Shan Yu wrote:
>
> Hi! I want to use TMinuit and fit a 2D histogram. Say fit d0 = Acos(phi0)+
> Bsin(phi0), A and B are free parameters. Could you show me an example to
> do it? Thanks!
>
> -Eiko
>
> ******************************************************************************
> Shin-Shan Yu
> Graduate Student, Dept. of Physics, University of Pennsylvania
> Office: B0 trailer 170 P
> Phone: (O) 630-840-3509
> (H) 630-428-0230
> Home Page: http://newton.hep.upenn.edu/~eiko/my.html
> ******************************************************************************
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