close all
clear all 
clc

t = -1:.01:5;
s = (t>=0).*exp((-1+1i*2*pi)*t);
figure
subplot(2,2,1)
plot(t,real(s))
grid on
axis([-1 5 -1.1 1.1])
title('real part')
subplot(2,2,2)
plot(t,imag(s))
grid on
axis([-1 5 -1.1 1.1])
title('imaginary part')
subplot(2,2,3)
plot(t,abs(s))
grid on
axis([-1 5 -.1 1.1])
title('absolute value')
subplot(2,2,4)
plot(t,angle(s))
grid on
yticks([-pi,-pi/2,0,pi/2,pi])
yticklabels({'-\pi','-\pi/2','0','\pi/2','\pi'})
axis([-1 5 -3.5 3.5])
title('phase')

% printing figure in png format
set(gcf,'PaperUnits','inches','PaperPosition',[0, 0, 8/1.5, 6/1.5])
print -dpng homework4.png -r100