function [output1, output2, output3] = vdp3(t, y, flag) if strcmp(flag, '') mu = 1; output1 = [y(2); mu*(1-y(1)^2)*y(2)-y(1)]; % dy/dt elseif strcmp(flag, 'init'), output1 = [0; 25]; % Time span output2 = [3; 3]; % Initial conditions output3 = odeset; % ODE options end