Hi I am trying to solve a simple set of coupled ODE's by ODE45. The coupled system is given by: Code (Text): 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: Code (Text): 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. Maybe it is due to the very rapid rates in the equations. Do I have any options here, or am I not able to solve for the transient behavior? Thanks in advance. Best, Niles.