#!/usr/bin/python
# -*- coding: utf8 -*-
importmatplotlib.pyplotasplt
importmatplotlibasmpl
importnumpyasnp
frommathimport *
code_website = 'http://commons.wikimedia.org/wiki/User:Geek3/mplwp'
try:
 importmplwp
except ImportError, er:
 print 'ImportError:', er
 print 'You need to download mplwp.py from', code_website
 exit(1)
name = 'mplwp_Dickman_function_log.svg'
fig = mplwp.fig_standard(mpl)
xlim = 0, 15; fig.gca().set_xlim(xlim)
ylim = 1e-19, 1e1; fig.gca().set_ylim(ylim)
fig.gca().set_yscale('log')
fig.gca().yaxis.set_major_locator(mpl.ticker.FixedLocator(np.logspace(-18, 0, 10)))
mplwp.move_axes(fig, 8, 0)
n = 100 * 4 # multiple of 4
dx = 1. / n
x = np.arange(xlim[0], xlim[1] + dx/2., dx)
y = np.empty_like(x)
for i, xx in enumerate(x):
 if xx <= 1.0:
 y[i] = 1.0
 elif xx <= 2.0:
 y[i] = 1.0 - log(xx)
 else:
 # Simpson's rule to integrate x * y(x) = \int_{x-1}^x y(x) dx
 s = y[i-n]
 s += 2. * np.sum(y[i-n+2:i-1:2])
 s += 4. * np.sum(y[i-n+1:i:2])
 y[i] = s / (3. * xx / dx - 1.)
plt.plot(x, y, label='Dickman function')
plt.legend(loc='upper right').get_frame().set_alpha(0.9)
plt.savefig(name)
mplwp.postprocess(name)