Need to use ode45 to solve a problem

I need to use ode 45 to solve the next problem.

The only thing I can't figure out is how to use the function on R(t-T) (T is a constant).

Is there a way to solve it this function?

Answer 1

[Torsten]

This is a delay differential equation.

You will have to use DDE23 instead of ode45.

[Noam Lusthaus]

And if T is known and is a constant?

[John D'Errico]

http://scholarpedia.org/article/Delay-differential_equations#:~:text=Delay%20differential%20equations%20differ%20from%20ordinary%20differential%20equations,%28t-%20au_1%29%2C%20y%20%28t-%20au_2%29%2C%5Cldots%2C%20y%20%28t-%20au_k%29%29

Delay differential equations can and often do involve a constant time lag or delay. See the link I show, to note the first example, described in the very first paragraph.

As Torsten said, you will use DDE23.