Lotka-volterra with ode45

I have the following system of differential equations:

P' = P − 0.05PR

R' = −0.5R + 0.02PR

My function is the following one:

function xdot = Lotka(t,x)
xdot = [x(1) - 0.05*x(1)*x(2); -0.5*x(2)-0.02*x(1)*x(2)];

To find the solution i use ode45:

[t,x] = ode45(@Lotka, [0 20],[10 10]);
plot(t,x(:,1));
hold on
plot(t,x(:,2));

But Matlab is still running... No error is given... It just keeps running. What went wrong?

Answer 1

[James Tursa]

Problem may be stiff. Try ode15s instead.