clc
clearvars
close all

M=1; % 1 (início), 10 e 100 (final)
s=linspace(-10,10,400*M);
fs=2*M*(sin(2*pi*s*M)./(2*pi*s*M));

figure(1)
plot(s,fs,'-b')
hold on
plot([-10 10],[0 0],'k-',[0 0],[-M 2.5*M],'k-')
hold off
axis([-10 10 -M 2.5*M])
xlabel('s')
ylabel('f(s)')
grid on

text(-0.5,2*M,'2M') % valor de fs para s=0
text(1/(4*M),0.05*M,'s=1/2M') % primeiro valor de s para fs=0