"""
Exercise A.19 from "A primer on..."
Implement a scaled version of the logistic
growth model, and experiment with different
parameter values. 
"""


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()


"""
Terminal> growth_logistic2.py 0.3 1 50
(gives a "well-behaved" plot)
Terminal> growth_logistic2.py 0.3 2 50
(gives a plot with oscillates around y=1)
Terminal> growth_logistic2.py 0.3 3 50
(plot with more dramatic oscillations)
"""