#!/usr/bin/python
# -*- coding: utf8 -*-

import matplotlib.pyplot as plt
import matplotlib as mpl
import numpy as np
from math import *

code_website = 'http://commons.wikimedia.org/wiki/User:Geek3/mplwp'
try:
    import mplwp
except ImportError, er:
    print 'ImportError:', er
    print 'You need to download mplwp.py from', code_website
    exit(1)

name = 'mplwp_Ei_E1_positive.svg'
fig = mplwp.fig_standard(mpl)

xlim = 0,2.5; fig.gca().set_xlim(xlim)
ylim = -5,7; fig.gca().set_ylim(ylim)
fig.gca().xaxis.set_major_locator(mpl.ticker.MultipleLocator(0.5))
fig.gca().yaxis.set_major_locator(mpl.ticker.MultipleLocator(1))
mplwp.mark_axeszero(fig.gca())

import mpmath
x = np.linspace(0, xlim[1], 5001)[1:]
yei = [mpmath.ei(xx) for xx in x]
ye1 = [mpmath.e1(xx) for xx in x]

plt.plot(x, yei, label=r'Ei', zorder=-1)
plt.plot(x, ye1, label=r'$E_1$', zorder=-2)
plt.legend(loc='upper center')

plt.savefig(name)
mplwp.postprocess(name)