function deriv = lorzrk(s,t,param) % Returns right-hand side of Lorenz model ODEs % Inputs % s State vector [x y z] % t Time (not used) % param Parameters [r sigma b] % Output % deriv Derivatives [dx/dt dy/dt dz/dt] %* For clarity, unravel input vectors x = s(1); y = s(2); z = s(3); r = param(1); sigma = param(2); b = param(3); %* Return the derivatives [dx/dt dy/dt dz/dt] deriv(1) = sigma*(y-x); deriv(2) = r*x - y - x*z; deriv(3) = x*y - b*z; return;