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% Simple ODE system for damped pendulum, with sinusoidal forcing
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function dx_dt = f5(t,x)
x1 = x(1);	%s1
x2 = x(2);	%s1_dot
x3 = x(3);	%s2
x4 = x(4);	%s2_dot
global  w02 f_input k l
input = feval(f_input,t);
dx_dt = [x2; -w02*(x1-l)+w02*(x3-x1-l) ; x4 ; w02*(x1-x3+l)+input];