void cangaroo_fit(void)
{
  float x[6] ={0.258.,0.299., 0.367., 0.540., 0.962., 2.454.};
  float ex[6]={0.064., 0.066., 0.080., 0.102., 0.356., 0.653.};
  float y[6] = {0.14e-8, 0.82e-9, 0.2e-9, 0.54e-10, 0.3e-11, 0.73e-13};
  float ey[6]= {0.06e-8, 0.22e-9, 0.08e-9, 0.19e-10, 0.28e-11, 1.19e-13};


  TGraphErrors * gr = new TGraphErrors(6,x,y,ex,ey);
  gr->SetMinimum(1e-15);

  TF1 * f =new TF1("f","[0]*pow(x,[1])",0.200,3.000);
  f->SetParameter(0,1e-11);
  f->SetParameter(1,-4.);

  // f->SetParameter(1,-4.4);

  TCanvas * cc = new TCanvas("cc","cc",600,400);
  cc->SetGridx();
  cc->SetGridy();
  cc->SetLogx();
  cc->SetLogy();


  gr->Draw("AP");
  gr->Fit(f,"RLM","");

}