w = 2*pi;

t = linspace(-0.5,0.5);

x1 =  cos(w*t)+sin(w*t);
x2 =  cos(w*t)-sin(w*t);
x3 = -cos(w*t)+sin(w*t);
x4 = -cos(w*t)-sin(w*t);

plot(t,x1); hold on;
plot(t,x2);
plot(t,x3);
plot(t,x4);