'''This script plots a logarithmic spiral (Fig. 14.12) and can be used for zooming in.
'''

from numpy import pi, exp, cos, sin, arange
import matplotlib.pyplot as plt

a, b = -4*pi, 2.1*pi
dt = 1e-4
t = arange(a, b, dt) 

plt.plot(exp(t)*cos(t), exp(t)*sin(t))
plt.axis([-100, 800, -200, 300])

plt.plot([-90, 750],[0, 0],'k',751,0,'k>',[0, 0],[-150, 250],'k',0, 252,'k^')
plt.show()