[交流] 二阶微分方程组化为一阶微分方程组的方法

function question_24
clear;clc
%2017-2-13
U=100;
f=[1 4];
L=[1 2];
y0=[1 2 3 4];
tspan=[0 5];
[t,y]=ode23(@fun,tspan,y0);
plot(t,y(:,1),'-o',t,y(:,2),'-.')
function dydt=fun(t,y)
dydt=[y(1);
    y(2);
    1/2*(U-(2*y(3)-y(4)+4*pi^2*(2*f(1)^2*L(1)*y(1)-f(2)^2*L(2)^2*y(2))));
    1/2*(U-2*y(4)-4*pi^2*f(2)^2*L(2)*y(2))];
end
end

2楼: Originally posted by WanderingHeart at 2017-02-13 11:52:45
应该是化成四个方程的方程组咯？