Pointer to histogram

Tadeusz Pytlos (pytlos@fizwe5.fic.uni.lodz.pl)
Tue, 7 Apr 1998 18:32:19 +0200 (CEST)

Hello Rooters,
I can't understand how to operate on histograms.
I just want to receive h14=h4, but I solved it
in quite unelegant way. Would you tell me what is wrong in my macro?
I reckon that operating togeher on objects and pointers
causes a complicating notation. I wish there was no pointers at all
or there were hidden pointers, but I understand that there are many
benefits of pointers...
Best wishes,
Tadeusz

{
//////////////////////////////////////////////////////////
// This file has been automatically generated
// (Mon Nov 24 12:46:19 1997 by ROOT version 1.03/07)
// from TTree kas/BASKET
// found on file: dst00459.root
//////////////////////////////////////////////////////////

//Reset ROOT and connect tree file
gROOT->Reset();
TFile hfile("dep.root");
page = new TCanvas("page","Example",0,0,500,700);
page->SetFillColor(10);
page->Divide(1,1);

TH1F *h44 = new TH1F("h44","Example",100,0,50);
TH1F *h14 = new TH1F("h14","Example",100,0,50);
// Of course there h4 is the same.

// It's correct
// h44->Add(h4,h4);
// h14->Add(h44,h4,1,-1);
// There are nice figures

// It's wrong
h44=(*h4)+(*h4);
h14=(*h4);
// There is nothing ...

Int_t k;
char padname[20];
char hname[20];
TH1 *h;

k=0;
sprintf(padname,"page_%d",k+1);
TPad *pad = (TPad*)page->GetPrimitive(padname);
pad->cd();
pad->SetGrid();
pad->GetFrame()->SetFillColor(42);
pad->GetFrame()->SetBorderMode(-1);
pad->GetFrame()->SetBorderSize(5);
pad->Draw();

sprintf(hname,"h1%d",k+4);
h=(TH1F*)hfile.Get(hname);
h.SetLineWidth(2);
h.SetLineStyle(1);
h.SetLineColor(4);
h.SetXTitle("E[MeV]");
h.SetYTitle("N");
h.SetMinimum(0);
h.SetMaximum(2.5e5);
h.Draw();

sprintf(hname,"h4%d",k+4);
h=(TH1F*)hfile.Get(hname);
h.SetLineWidth(2);
h.SetLineStyle(1);
h.SetLineColor(2);
h.SetMinimum(0);
h.SetMaximum(2.5e5);
h.Draw("same");

page.Update();
TPostScript mps("dep21.ps");
page.Draw();
mps.Close();

page->cd();

}

--
Tadeusz Pytlos        
mailto:pytlos@fizwe5.fic.uni.lodz.pl 
Lodz, Poland