i am not getting chaotic plot because of warning

Question

nune pratyusha 2022-2-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1648465-i-am-not-getting-chaotic-plot-because-of-warning

评论： Walter Roberson 2022-2-16

function dx = compactchua(t,x)

dx=zeros(4,1);

dx(1) = -(1/(8200*47*1e-9))*x(2);

dx(2) = (((x(3)-x(2))/2000) -(x(4).^3*4.7e3+1e3))/6.8e-9;

dx(3) = ((x(2)-x(3))/2000 - x(4))/68e-9;

dx(4) = (x(3))/(22*10^-9);

end

[t,x] = ode15s(@compactchua,[0 5e-7],[0 12.24e-3 12.24e-3 1.7]);

plot(x(:,2),x(:,3));

error

Warning: Failure at t=6.943264e-08. Unable to meet integration tolerances without reducing the step size below

the smallest value allowed (2.117582e-22) at time t.

>>

2 个评论
显示无隐藏无

David Goodmanson 2022-2-16

Hi nune,

you might want to double check the equations, especially the signs, because the solution gives the impression of wanting to increase without bound.

Walter Roberson 2022-2-16

Which equations are you using?

https://people.eecs.berkeley.edu/~chua/papers/Pospisil00.pdf

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Bhavana Ravirala 2022-2-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1648465-i-am-not-getting-chaotic-plot-because-of-warning#answer_897440

Hi Pratyusha,

In case of sharp discontinuities in the reference input, it is possible that this warning is generated at intermediate time steps. As it tries to reduce the time step to a small amount in order to counter the abrupt change due to the discontinuity in the reference input.

For sharp discontinuities, it might not be possible to avoid this warning. However, for non-discontinuous inputs we can set relative and absolute tolerance to a higher number than the default setting.

For more information refer the below links:

Absolute and relative tolerance definitions - (mathworks.com)

https://www.mathworks.com/help/matlab/ref/odeset.html#:~:text=RelTol%20%E2%80%94%20Relative%20error%20tolerance

Hope this helps.