Solve and plot the phase portrait for van der pol ODE with time dependent term
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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
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/211639/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/211640/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/211641/image.png)
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 commentaires
Jan
le 31 Mar 2019
And now all visitors of this page see this junk: "Solve mmmmmmmmmmmmmmmmmmmmmmmmmmmmmm" 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.
Réponses (1)
madhan ravi
le 27 Mar 2019
Modifié(e) : madhan ravi
le 27 Mar 2019
g,lambda
%^—-missed it
Don’t name variable lambda (will shadow in-built function gamma())
1 commentaire
madhan ravi
le 27 Mar 2019
Modifié(e) : madhan ravi
le 27 Mar 2019
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.
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