%
%  code10Fe.m -- 08 nov 02 -- djm
%
%  - runge-kutta method for coupled pendula

clear

%  set initial value as column vector

IV = [1  0  0  0];

%  invoke runge-kutta solver

opt = odeset('RelTol',1e-3,'AbsTol',1e-6);
[t y] = ode45(@Fpendula,[0 40*pi],IV,opt);

%  plot results for theta(t) and phi(t)

figure(1);  clf;  hold on

plot(t,y(:,1),'b')
plot(t,y(:,3),'r')

title('\bf runge-kutta solution')
xlabel('\bf t-axis')
ylabel('\bf \theta(t) in blue & \phi(t) in red')