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% Compute position and velocity of coupled masses with f external
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

s10		= 0.2;			% initial position
s1_dot0		= -1;			% initial velocity
s20		= 0.4;			% initial position
s2_dot0		= -1;			% initial velocity

tspan		= [0 10];		% time boundaries
x0		= [s10;s1_dot0;s20;s2_dot0];

global w02 f_input k l
w02	= 5;
l=1;

f_input = inline('0'); %no external forcing. 

[t,x]	= ode45('f5',tspan, x0);

x1	= x(:,1);
x2	= x(:,2);
x3	= x(:,3);
x4	= x(:,4);


subplot(3,1,1)
plot(t,x1,t,x3);
xlabel('time in s'); ylabel('positions (m)'); 
title('simple damped pendulum with forcing');
subplot(3,1,2)
plot(t,x2,t,x4);
xlabel('time in s'); ylabel('velocities (m/s)'); 
subplot(3,1,3)
plot(t,f_input(t));
xlabel('time in s'); ylabel('input');