function dY=pendulatest1(t,Y,options,N);

w=0.55+t/300;
M1=0.9;
M=6.5;
aa=0.03;

p=-sin(w*t)*M1;
%p=cos(w*t)*(M*(1-exp(-t/20))+(M1-M)*(1-exp(-t/170)));

dY(1)=Y(N+1);
dY(N+1)=4*(p+Y(2)-2*Y(1))-sin(Y(1))-aa*Y(N+1); 
dY(N)=Y(2*N);
dY(2*N)=4*(Y(N-1)-Y(N))-sin(Y(N))-aa*Y(2*N); 

for n=2:N-1,
dY(n)=Y(N+n);
dY(N+n)=4*(Y(n+1)+Y(n-1)-2*Y(n))-sin(Y(n))-aa*Y(N+n); 
end

dY=dY';