function calcJ2()

  m = input( 'Masse/kg = ' );
  ra = input( 'Außenradius/m = ' );
  ri = input( 'Innenradius/m = ' ); 

  J = m/2* ( ra^2 + ri^2 ); 
  
  fprintf( 'Trägheitsmoment J = %g kg m^2 \n', J );
  