#!/usr/bin/env python
# -*- coding: utf-8 -*-

# This program is copyright 2014, P. Lutus
# It is released under the GPL:
# http://www.gnu.org/copyleft/gpl.html

# Created on Aug 8, 2014 12:37:36 PM

import pylab as g

# modified logistic function with non-renewable term
  
kr = 100 # renewable carrying capacity
kn = 300 # nonrenewable carrying capacity
nr = .04 # nonrenewable rate of consumption
p = 1    # initial population
r = .05  # population growth rate per period

a = []
b = []
c = []
d = []

for t in range(101):
    p *= 1 + r * (kn+kr-p)/kr
    kn = max(kn-p * nr,0)
    a.append(t)
    b.append(p)
    c.append(kr)
    d.append(kn+kr)

g.plot(a,c)
g.plot(a,b)
g.plot(a,d)
g.grid(True)
g.gcf().set_size_inches(5,4)
# g.savefig('../graphics/nonrenewable_graph.png')
g.show()