{
 TF1  *f1 = new TF1("f1","gaus(x)",0,10);
 TF1  *f2 = new TF1("f2","10.-x",0,10);
f2->SetParameter(0,1);
f2->Draw();
f1->SetParameter(0,2);
f1->SetParameter(1,4);
f1->SetParameter(2,2.5);
f1->Draw();
TF1  *f3 = new TF1("f3","f1+f2",0,10);
f3->Draw();
f3->SetParameter(0,3);
f3->SetParameter(2,0.5);
f3->Draw();
f2->Draw("same");
f1->SetParameter(0,3);
f1->SetParameter(2,0.5);
f1->Draw("same");
}