function xprime = lorenz(x)
% rhs for lorenz strange attractor system
sigma = 10;
b = 8/3;
r = 28;

xprime(1) = sigma*(x(2)-x(1));
xprime(2) = r*x(1) - x(2) - x(1)*x(3);
xprime(3) = x(1)*x(2) - b*x(3);