www.gusucode.com > MATLAB2008应用程序接口编程技术源码程序 > MATLAB2008应用程序接口编程技术源码程序/code/第4章/4.2/yprime.m

    function yp = yprime(t,y)

mu = 1/82.45;
mus = 1-mu;
r1 = norm([y(1)+mu, y(3)]);   % Distance to the earth
r2 = norm([y(1)-mus, y(3)]);  % Distance to the moon
yp(1) = y(2);
yp(2) = 2*y(4) + y(1) - mus*(y(1)+mu)/r1^3 - mu*(y(1)-mus)/r2^3;
yp(3) = y(4);
yp(4) = -2*y(2) + y(3) - mus*y(3)/r1^3 - mu*y(3)/r2^3;
% yp = yp';