Question

请问这道题怎么用matlab程序写？

Answer 1

可以这样写

---

clc;clear

odefun = @(t,y)[y(2); y(3); 3*y(3) + y(2)*y(1)];

tspan = [0,1];

y0 = [0;1;-1];

[t1, y1] = ode45(odefun, tspan, y0);

plot(t1, y1(:,1), 'k.')

hold on

plot(t1, y1(:,2), 'c.')

[t2, y2] = ode113(odefun, tspan, y0);

plot(t2, y2(:,1), 'b*')

plot(t2, y2(:,2),'r+')

legend('ode45-y_1','ode45-y_2','ode113-y_1','ode113-y_2')

---

y-t图

e可见ode45是时间步均匀的，ode113的时间步是可变的