Why is my plot blank? (New to MATLAB)

for x = linspace(-pi,pi,.01)
    S(x) = (2.*H(x))-1;
end
figure
plot(S(x),x,'-r*');
axis([-pi pi -3 3]);
title('S(x) vs. x');
xlabel('x');
ylabel('S(x)');

My assignment is dealing with the Fourier Series and the Heaviside Function and I am trying to plot S(x) vs. x but my plot is blank.

Answer 1

[Erivelton Gualter]

Try the following:

x = -pi:.1:pi;
for i=1:length(x)
    S(i) = (2.*heaviside(x(i)))-1;
end
figure
plot(S,x,'-r*');
axis([-pi pi -3 3]);
title('S(x) vs. x');
xlabel('x');
ylabel('S(x)');