Generated with the following code:

import numpy as np
import matplotlib.pyplot as plt

frames_per_cycle = 256
freq = 3
nr_frames = frames_per_cycle * freq
phase = 0
audio = np.fromfunction(lambda y : (y /  frames_per_cycle + phase) % 1 - 0.5, (nr_frames,))
maxfreq = 16
freq_plotstyle = "o"
ft = np.fft.rfft(audio[:frames_per_cycle]) / (frames_per_cycle / 2)
if maxfreq != None :
    ft = ft[:maxfreq]
#end if
abs_mag = True

fig, ax = plt.subplots(nrows = 2 + int(not abs_mag))
ax[0].plot(np.linspace(0, freq, nr_frames), audio, "-")
ax[0].set_title("Time Domain")
if abs_mag :
    ax[1].plot(np.linspace(0, len(ft), len(ft)), np.abs(ft), freq_plotstyle)
    ax[1].set_title("Frequency Domain")
else :
    ax[1].plot(np.linspace(0, len(ft), len(ft)), np.real(ft), freq_plotstyle)
    ax[1].set_title("Frequency Domain (Real)")
    ax[2].plot(np.linspace(0, len(ft), len(ft)), np.imag(ft), freq_plotstyle)
    ax[2].set_title("Frequency Domain (Imag)")
#end if
plt.subplots_adjust(hspace = 0.5)
plt.show()

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