{

Int_t nDots = 4;
Double_t dac[4] = {1., 2., 3., 4.};
Double_t npe[4] = {1.56, 2.03, 2.89, 3.15};
Double_t sigma[4] = {.2, .3, .4, .5};
 
TGraphErrors *g = new TGraphErrors(nDots, dac, npe, NULL, sigma);

char graph_title[200];
sprintf(graph_title, "Led Characteristic curve. Brd=%d Ch=%d", 3, 2);
g->SetTitle(graph_title);
char canvas_name[200];
sprintf(canvas_name, "canv%d", 2); 
TCanvas *c = new TCanvas(canvas_name, canvas_name);
c->cd();
g->Draw("AP");
g->GetXaxis()->SetTitle("DAC");
g->GetYaxis()->SetTitle("pe");
g->SetMarkerStyle(8);
g->SetMarkerSize(.5);
g->SetMarkerColor(4);
gPad->SetGridx();
gPad->SetGridy();
TPaveText *pave = new TPaveText(0.12, 0.58, 0.32, 0.88, "NDC");
char tmp_str[200];
sprintf(tmp_str, "run = %d", 3);
pave->AddText(tmp_str);
sprintf(tmp_str, "time = %.3f", 34.5);
pave->AddText(tmp_str);
sprintf(tmp_str, "single_pe_dac = %d", 15);
pave->AddText(tmp_str);
sprintf(tmp_str, "single_pe = %.2f", .23);      
pave->AddText(tmp_str);

sprintf(tmp_str, "single_pe_eff = %.2f %%", 34);      
TText *te = pave->AddText(tmp_str);
te->SetTextColor(2);

sprintf(tmp_str, "max_pe = %.2f", 79);      
TText *tm = pave->AddText(tmp_str);
tm->SetTextColor(2);

pave->Draw();

char canvas_file[200];
sprintf(canvas_file, "led_fit_run%d_ch%d.C", 13, 2); 
c->SaveAs(canvas_file);
}