Solve and plot the phase portrait for van der pol ODE with time dependent term

9 次查看（过去 30 天）
F.O
F.O 2019-3-27
评论： Rena Berman 2019-4-2
I want to solve this system of ode by ode45 and then plot the x1 and x2 with t and phase portrait later but I got error which i couldint figure out
How i could draw the vector field and eigen vectors in the phase portrait because i dont get by using ode set and odephase 2
function [dxdt] = myode(t,x,gt,g,lambda,gamma,omega)
g=interp1(gt,g,t)
dxdt=zeros(2,1);
dxdt(1)=x(2);
dxdt(2)=lambda.*(1-x(1)^2)*x(2)-x(1)+g;
end
%script
gamma=0.25;
omega=[1.04 1.1];
gt=[0 ,500]
g=gamma.*sin(omega(1).*gt)
% g=gamma.*sin(omega(2).*gt)
lambda=0.01;
x0=[1 0]
tspan=[0 500];
opts = odeset('RelTol',1e-2,'AbsTol',1e-4);
[t2,x2]=ode45(@(t,x) myode(t,x,gt,g,gt,lambda,gamma,omega(1)),tspan,x0,opts);
% ploting the phase portait
function PLOT_VDP()
figure(1)
options=odeset('OutputFcn', @odephas2);
lambda=0.01;
gamma=0.25;
omega=[1.04 1.1];
x0=[1; 0]
x01=[3;0]
tspan=[0 500];
[t,x]=ode45(@(t,x) myode(t,x,g,lambda,gamma,omega(1)),tspan,x0,options);
end
  4 个评论
显示 2更早的评论
Jan
Jan 2019-3-31
And now all visitors of this page see this junk: "Solve mmmmmmmmmm​mmmmmmmmmm​mmmmmmmmmm" and "kkklllllll". Come on, F.O, you can see, that leaving junk in the forum is not useful.
The nature of the forum is the sharing of solutions. So explain your solution in an own answer and accept it, instead of inserting nonsense. Imagine how hillarious this forum would look like, if all users roll an angry armadillo over the keyboard, when their problem is solved.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

madhan ravi
madhan ravi 2019-3-27
编辑：madhan ravi 2019-3-27
g,lambda
%^—-missed it
Don’t name variable lambda (will shadow in-built function gamma())
  1 个评论
madhan ravi
madhan ravi 2019-3-27
编辑：madhan ravi 2019-3-27
After someone answers the question it’s not appropriate to edit the question!! You have some problems with declaring the input arguments while calling the function, analyse slowly and observe what obvious mistake you made.

请先登录，再进行评论。

类别

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

标签

产品


版本

R2018b

Community Treasure Hunt

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

Start Hunting!

Translated by