function periodic in matlab

i have a function (f=x^2 for -pi/2<=x<=pi/2) and i want to make this function periodic , how i can do it?

Answer 1

[the cyclist]

I think this does what you want:

x = -3*pi : 0.01 : 3*pi;
f = @(x) (mod(x+pi/2,pi) - pi/2).^2;

figure
plot(x,f(x))