how can i generate a single period rectangular pulse in both negative and positive y axis together and seperate negative y axis rectangular wave

fs=50; t=-1.5:1/fs:1.5; y=2*(rectpuls(t)); subplot(3,1,2) plot(t,y); axis([-1.7 1.7 -2 2]) title('rectangular waveform'); xlabel('time(ms)'); ylabel('amplitude'); grid on;

this is giving me only positive rectangular pulse. i want to generate it in both positive and negative y axis