Plotting third order differential equation using ode45

2 次查看（过去 30 天）
vaibhav gupta
vaibhav gupta 2020-12-6
评论： Ameer Hamza 2020-12-7
Hello
Could you please how to plot below third order differential equation using ODE45.
d3x/dt3 = +-1

请先登录，再回答此问题。

采纳的回答

Ameer Hamza
Ameer Hamza 2020-12-6
编辑：Ameer Hamza 2020-12-6
You need to convert this 3-rd order ODE to 3 first order ODEs. Also due to +-1, you have two systems of ODEs. Try following code
odeFun = @(t,x,a) [x(2);
x(3);
a];
tspan = [0 10];
IC = [1; 0; 0];
ode45(@(t,x) odeFun(t,x,1), tspan, IC)
hold on
ode45(@(t,x) odeFun(t,x,-1), tspan, IC)
legend({'$x$', '$\dot{x}$', '$\ddot{x}$'}, 'Interpreter', 'latex', 'FontSize', 16, ...
'Location', 'best')
  2 个评论
vaibhav gupta
vaibhav gupta 2020-12-6
编辑：vaibhav gupta 2020-12-6
Thank you! I just wanted to plot result of first ode. How can i supress rest? Also, i see that plot is continuing and not stopping at all. Shoudln't it be stopped rendering at some point of time?
Ameer Hamza
Ameer Hamza 2020-12-7
Try this
odeFun = @(t,x,a) [x(2);
x(3);
a];
tspan = [0 10];
IC = [1; 0; 0];
[t, y] = ode45(@(t,x) odeFun(t,x,1), tspan, IC);
plot(t, y(:,1))
hold on
[t, y] = ode45(@(t,x) odeFun(t,x,-1), tspan, IC);
plot(t, y(:,1))
legend({'$+1$', '$-1$'}, ...
'Interpreter', 'latex', ...
'FontSize', 16, ...
'Location', 'best')

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Ordinary Differential Equations 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by