Lissajous curves

And after the Epitrochoids, we're going to see another family of wonderful figures: The Lissajous curves. The equations that describe these curves are the following

the curves vary with respect the parameter t and their appearance is determined by the ratio a/b and the value of δ.
As usual, I made a snippet to visualize them:

from numpy import sin,pi,linspace
from pylab import plot,show,subplot

a = [1,3,5,3] # plotting the curves for
b = [1,5,7,4] # different values of a/b
delta = pi/2
t = linspace(-pi,pi,300)

for i in range(0,4):
 x = sin(a[i] * t + delta)
 y = sin(b[i] * t)
 subplot(2,2,i+1)
 plot(x,y)

show()

This is the result

and setting delta = pi/4 the we have

while, if we set a = [1,2,2,1], b = [5,8,1,2] and delta = 0.709 the result is