function Ut=Pendel(Y_0,g,l)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Pendel-ligning...
% Ut(1,1)=(d/dt)Theta...
% Ut(2,1)=(d/dt)^2Theta...
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Ut(1,1)=Y_0(2,1);
Ut(2,1)=-(g/l)*sin(Y_0(1,1));