#!/usr/bin/env python

# 2017-02-12 Orbit graph example
# http://algoristo.com/teaching/

import math
from random import random, choice

ninit = 10
niter = 10000

def rotate(x, y, degrees):
    s = math.sin(math.pi*degrees/180)
    c = math.cos(math.pi*degrees/180)
    return c*x - s*y, c*y + s*x

# Example: Gingerbreadman map
def gingerbread(x, y):
    # Constants -- try changing these
    M = 1
    L = 0
    A = 1
    B = 1
    
    return M*(1 + 2*L) - A*y + B*abs(x - L*M), x/A

ifs = [gingerbread]

datfile = open("orbit.dat", "w")

for i in range(1, ninit + 1):
    # Random point -- needs a wider range than 0 to 1
    x = 2*random()
    y = 2*random()

    for j in range(1, niter + 1):
        f = choice(ifs)
        x, y = f(x, y)

        # Write each stage of the orbit to the same file
        datfile.write("%f %f\n" % (x, y))

datfile.close()