System of non linear differential equations

Hi, I'm trying to solve a system of non linear differential equations, in which dv/dt is a function of two parameters (v and r) and dr/dt is a function of v and r. I need to obtain the values of v and r. Any suggestions?

Answer 1

[Sara]

You can use ode45 for non-stiff problems and ode15s for stiff problems

[Antonio]

thank you:) now I want to transform the two differential equations into a space state system, because I wanna know the step response through the command "lsim". How can I resolve?

[Sara]

I can't help you with that. You may want to post a new question.