#include "TF1.h"
#include "TGraph.h"
#include "TMinuit.h"

void otherChi2(int &n,double *x, double &f, double *p, int k){
  double chi2=0;
  for (int i=0;i<k;i++) chi2+=(x[i]-p[i])*(x[i]-p[i]);
  f=chi2;
}

void example03_A(){

  gMinuit = new TMinuit(2);
  gMinuit->SetFCN(otherChi2);

  TGraphErrors *myData = new TGraphErrors("dataset1.dat","%lg %lg %lg");

  TF1 *myFunc = new TF1("myF","[0]*x+[1]",0,10);
  myFunc->SetParName(0,"alpha");
  myFunc->SetParName(1,"omega");
  
  myData->SetTitle("Cross Section #sigma_{CC} (E_{#nu})");
  myData->SetMarkerStyle(kFullSquare);
  myData->SetMarkerColor(kRed);
  myData->GetXaxis()->SetTitle("E_{#nu} (GeV)");
  myData->GetXaxis()->SetTitleSize(0.050);
  myData->GetYaxis()->SetTitle("#sigma #times 10^{-42} m^{2}");
  myData->GetYaxis()->SetTitleSize(0.050);
  
  myData->GetXaxis()->SetLabelSize(0.045);
  myData->GetYaxis()->SetLabelSize(0.045);
  
  myData->Draw("APE");
  
  myData->Fit(myFunc);
  
  
}