double myFunc(double *x, double *par){
  double result = 1. + .1/(1.+exp(+((x[0])*(x[0]))/1.));
  return result;
}

int funzione() {
  TF1 miaFunc("miaFunc",myFunc,-3.14.,3.14.,0);
  miaFunc.SetMinimum(0.7);
  miaFunc.DrawClone();
  h1f = new TH1F("h1f","Test random numbers",200,-3.14,3.14);
  h1f->FillRandom("miaFunc",10000000);
  h1f->Draw();
}