const int n = 6; float x[n] = {0.092,0.83,0.94,0.81,0.12,0.1}; float 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 u,v; for (int 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"); %jsroot on gROOT->GetListOfCanvases()->Draw()