// file funktionen
void funktionen()
{
 TF1 *f1 = new TF1("f1","sin(x)", 0, 10 );
 TCanvas* c0 = new TCanvas("f1","f1",0,0,300,200);
 f1->Draw();
 TF1 *f2 = new TF1("f2","cos(x)", 0, 10 );
 TCanvas* c1 = new TCanvas("f2","f2",10,10,300,200);
 f2->Draw();         
 f1->Draw("same");         
 TF1 *f4 = new TF1("f4","abs(f1)/x", 0, 10 );   
 TCanvas* c2 = new TCanvas("f4","f4",20,20,300,200);
 f4->Draw();                                      
 gPad->SetLogy();
 TF2 *ff1 = new TF2("f5","abs(f1)*y**2", 0, 10, -10, 10 );
 TCanvas* c4 = new TCanvas("ff1","ff1",30,30,300,200);
 ff1->Draw("surf1");
 // options: lego cont surf  
 return;
}