by Daniel Shiffman. Create a more complex wave by adding two waves together.

```xspacing = 8    # How far apart should each horizontal location be spaced
maxwaves = 4    # total # of waves to add together
theta = 0.0

amplitude = []  # Height of wave
# Value for incrementing X, to be calculated as a function of period and
# xspacing
dx = []
yvalues = []

def setup():
size(640, 360)
frameRate(30)
colorMode(RGB, 255, 255, 255, 100)
w = width + 16
for i in range(maxwaves):
amplitude.append(random(10, 30))
period = random(100, 300)  # How many pixels before the wave repeats
dx.append((TWO_PI / period) * xspacing)
for _ in range(w / xspacing + 1):
yvalues.append(0.0)

def draw():
background(0)
calcWave()
renderWave()

def calcWave():
global theta
# Increment theta (try different values for 'angular velocity' here
theta += 0.02
# Set all height values to zero
for i in range(len(yvalues)):
yvalues[i] = 0
# Accumulate wave height values
for j in range(maxwaves):
x = theta
for i in range(len(yvalues)):
# Every other wave is cosine instead of sine
if j % 2 == 0:
yvalues[i] += sin(x) * amplitude[j]
else:
yvalues[i] += cos(x) * amplitude[j]
x += dx[j]

def renderWave():
# A simple way to draw the wave with an ellipse at each location
noStroke()
fill(255, 50)
ellipseMode(CENTER)
for x, v in enumerate(yvalues):
ellipse(x * xspacing, height / 2 + v, 16, 16)
```