void anpassung()
{
  TH1* h = new TH1F( "h", "Histogramm", 100, 0, 10 );
  TF1* f1 = new TF1( "f1", "exp(-x)*x", 0, 10 );

  h->FillRandom( "f1", 1000 );
  h->SetMarkerStyle( 20 );
  h->SetMarkerSize( 0.5 );

  TF1* ffit = new TF1( "ffit", "[0]*exp(-[1]*x)*x", 0, 10 );
  ffit->SetParameters( 10, 1 );
  h->Fit("ffit","","e");
}