function dy=trajectory1_eq0(t,y,l,g); 

%---2006.3.30----
%%%  nonlinear System

%---------------definition---------------------------------------
%                   g
%     q'' +   ---------- sin(q)=0
%                   l
%     x1:=q   x2:=q'
%     x'1=x2
%     x'2=-(g/l)sin(x1)
%-----------------------------------------------------------------
%----------------definition---   
%  y(1,1)   y(2,1)        
%           dy(1,1)        
%-----------------------------------------------------------------

global ni
dy=zeros(2,1);

dy(1,1)=y(2,1);
dy(2,1)= -(g/l) * sin( y(1,1) );







