Hi, MATLAB function ddesd can be used as it solves ODEs with variable delays:

https://fr.mathworks.com/help/matlab/ref/ddesd.html

Thank you! But how can I use this information in my situation? The delay as a function of t is determined by the differential equation included in the system.

Please look at the picture.

I can show my code, which works incorrectly.

clc;

sol = ddesd(@my1ddex1de,1,[1,1,1,1,0.01],[0,500])

plot3(sol.y(1,:),sol.y(2,:),sol.y(3,:));

deval(sol,500) - deval(sol,500-sol.y(4,end))

function dy1dt = my1ddex1de(t,y,Z)

r1 = 0.02;

r2 = 0.01;

F0 = 0.1;

ylag1 = Z(:,1);

S = y(5)*(ylag1(2)-y(2));

if (abs(S)F0) k2 = 1;

else k2 = 0;

end;

if (S

Hi, I heve not used ddesd, but according to the help the second argument "delays" must be a function that returns the values of the delays. These values may depend on both time t and the components of y.

Thanks for your answer!!!

I do not understand how to set the delay function as a solution to the differential equation included in the system. Any ideas?

Hi, I think you need the following commands and files:

https://www.radford.edu/~thompson/webddes/tutorial.pdf

http://matlab.cheme.cmu.edu/tag/delay-differential-equation/

http://www.unige.ch/~hairer/software.html

https://www.youtube.com/watch?v=IfggV4J2Qxk

Hi, there is an example of how to use the delay function in the MATLAB help page concerning ddesd.

Interested