// Program to illustrate use of ROOT random number and histogram classes
// Glen Cowan, RHUL, Physics, November 2007

#include <iostream>
#include <cmath>
#include <TH1D.h>
#include <TFile.h>
#include <TRandom3.h>

using namespace std;

int main(){

// Open output file (apparently needs to be done before booking)

  TFile file("simpleMC.root", "recreate");

// Book histograms, i.e., create TH1D objects
// 1st argument is a string; by convention same as object name
// 2nd argument is histogram title (will appear on plots)
// 3rd argument is number of bins (type int)
// 4th and 5th arguments:  upper and lower limits of histogram (type double)

  TH1D h_Uniform("h_Uniform", "uniform random numbers",  100,  0, 1.0);

// Create a TRandom3 object to generate random numbers

  int seed = 12345;
  TRandom3 ran(seed);

// Generate some random numbers and fill histograms

  const int numValues = 10000;
  for (int i=0; i<numValues; ++i){
    double r = ran.Rndm();             // uniform in ]0,1]
    h_Uniform.Fill(r);
  }

// Store all histograms in the output file and close up

  file.Write();
  file.Close();

  return 0;
}