![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/942629/image.png)
Why my ODE is not solving?
1 vue (au cours des 30 derniers jours)
Afficher commentaires plus anciens
I'm trying to solve the ODE with an input of a cosine wave (x1) but i am not getting the output in a wave form. Please help me out. Thanks!
function [] = call_spring()
t=0:0.001:10;
y0=[0,1];
x1=2.5*cos(4*pi*t);
[t,y]=ode45(@spring,t,y0);
plot(t,y,t,x1)
function dzdt = spring(t,y)
k=342; m=2.853; x1=2.5*cos(4*pi*t);
y1=y(1);
y2=y(2);
dzdt = [y2 ; (-k/m)*(x1-y1)];
end
end
0 commentaires
Réponse acceptée
Sam Chak
le 27 Mar 2022
Modifié(e) : Sam Chak
le 27 Mar 2022
Because of the sign in this line. (minus) (minus) = plus. It means that energy is continuously injected into the system, and destabilizes it.
(-k/m)*(x1 - y1)
function [] = call_spring()
t = 0:0.001:10;
y0 = [0, 1];
x1 = 2.5*cos(4*pi*t);
[t, y] = ode45(@spring, t, y0);
plot(t, y, t, x1)
end
function dzdt = spring(t, y)
k = 342;
m = 2.853;
x1 = 2.5*cos(4*pi*t);
y1 = y(1);
y2 = y(2);
dzdt = [y2;
(-k/m)*(x1 + y1)];
end
Result
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/942629/image.png)
Also, please double check your equation. Could be this one too:
(-k/m)*y1 + (1/m)*x1
4 commentaires
Sam Chak
le 27 Mar 2022
You are welcome, @Aung Moe Zaw
There are two vectors in y. To plot only the first vector, then replace
plot(t, y, t, x1)
with
plot(t, y(:,1), t, x1)
grid on
xlabel('Time, t')
ylabel('y_{1} and x_{1}')
title('Time response of y_{1}, perturbed by x_{1}')
legend('y_{1}', 'x_{1}')
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Ordinary Differential Equations dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!