Hi
I have a relatively simple set of coupled ODE's that I am trying to solve by ODE45. The following is the content of the .m-file, which shows the coupled system:
function xprime = eoms(t, x)xprime = [ 1e9 + 5.0e4*x(3) - 50*x(1); 4.0e1*x(1) - 3.3e3*x(2); 2.0e3*x(2) - 5e4*x(3) + 3.5e7*heaviside(t-1)*x(4); 1.0e3*x(2) - heaviside(t-1)*5.0e7*x(4)];
I solve it using the following command:
x0 = [0 0 0 0];tspan = [0, 2];[t, x] = ode45(@eoms, tspan, x0);
However when I compile MatLAB just keeps calculating, it doesn't give me a result. I think it has something to due with the fact that the Heaviside step-function, because if I take it out then it nicely solves the remaining part. I have also tried in a competing software, and the same thing happens (actually, there the solver just gives an error).
Maybe it is also due to the very rapid rates in the equations. Anyhow, I am really lost on what to do – unfortunately I need the transient behavior, so I can't just assume steady-state for some of the equations.
Do I have any options here?
Thanks in advance.
Best, Niles.
Best Answer