Re: plot("same")

Hello Holger,

See below:

On Tue, 8 Feb 2011, Holger Meyer wrote:

> Hello,
>
> how can I plot a histogram and a function in the same canvas so that
> both use the same scale?
> This macro (problem.C) shows the problem:
>
>
> Double_t Gaus2D(Double_t *x, Double_t *par)
> {
> if(par[2] > 0 && par[4] > 0)
> {
> double rx=(x[0]-par[1])/par[2];
> double ry=(x[1]-par[3])/par[4];
> return par[0]*TMath::Exp(-(rx*rx+ry*ry)/2.);
> }
> else
> return 0.;
> }
>
> problem() {
> TCanvas* cnv = new TCanvas("cnv","Canvas",800,400);
> cnv->Divide(2);
> cnv->cd(1);
>
> //draw a histogram
> TH2F* h2 = new TH2F("h2","Hist2D",50,-25.,25., 50,-25.,25.);
> h2->SetBinContent(1275,10.);
> h2->Draw("lego");
>
> //draw a function in another pad so it is easy to compare the range
> cnv->cd(2);
> TF2* f = new TF2("g2d",Gaus2D,-10.,10.,-10.,10.,5);
> f->SetParameter(0,10.);
> f->SetParameter(1,2.);
> f->SetParameter(2,3.);
> f->SetParameter(3,0.);
> f->SetParameter(4,3.);
> f->SetLineColor(616);
> f->Draw("surf");
>
> //plot the same function superimposed on the histogram
> //Why does it not respect the axis range given in this pad by the
> histogram?
> cnv->cd(1);

    f->SetMaximum(h2->GetMaximum());
    f->SetMinimum(h2->GetMinimum());