% DGL-Funktion für ode45 zur Funktion spirale( k ) 
function  dv_dt = Fun_Spirale( t, v, w2 )

   dv_dt(1,1) = v(2);         % dx /dt = vx
   dv_dt(2,1) = - w2 * v(1);  % dvx/dt = - w^2 * x
   
   dv_dt(3,1) = v(4);         % dy /dt = vy
   dv_dt(4,1) = - w2 * v(3);  % dvy/dt = - w^2 * y
   
   dv_dt(5,1) = v(6);         % dz /dt = vz
   dv_dt(6,1) = 0;            % dvz/dt = 0   
   
   