function zd = foo(t,z) alpha = 0.1; beta = 2.0; delta = 0.4; gamma = 4.0; x = z(1,:); y = z(2,:); xd = alpha*x - beta*x.*y; yd = -delta*y + gamma*x.*y; zd = [xd;yd]; % zd(1,:) = alpha*z(1,:); % zd(2,:) = -delta*z(2,:); endfunction