"""
Exercise A.19 from a primer on. Solve the
logistic equation and demonstrate that certain
parameter choices give rise to oscillating
solutions. For experiments of this kind it
is convenient to read in the parameters as
command line arguments, but hard-coding 
the values directly in the file is also 
perfectly fine. 
"""

import numpy as np
import matplotlib.pyplot as plt
import sys

y0 = float(sys.argv[1])
q = float(sys.argv[2])
N = int(sys.argv[3])

y = np.zeros(N + 1)

y[0] = y0
for n in range(1, N + 1):
    y[n] = y[n-1] + q * y[n-1] * (1 - y[n-1])

plt.plot(y)
plt.show()