#!/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_polygamma03.svg'
fig = mplwp.fig_standard(mpl)

xlim = -2,4; fig.gca().set_xlim(xlim)
ylim = -13,13; fig.gca().set_ylim(ylim)
mplwp.mark_axeszero(fig.gca())

import mpmath
for m in range(3+1):
    for i, tlim in enumerate([(-2, -1), (-1, -0), (0, 4)]):
        if tlim[1] <= 0.0:
            x = np.linspace(tlim[0], tlim[1], 1001)[1:-1]
        else:
            x = np.linspace(tlim[0], tlim[1], 5001)[1:]
        y = [mpmath.psi(m, xx) for xx in x]
        label = u'\u03c8'
        if m != 0:
            label += mplwp.unicode_sub(m)
        if i == 0:
            plt.plot(x, y, label=label)
        else:
            plt.plot(x, y, color=fig.gca().lines[-1].get_color())

plt.legend(loc='lower right').get_frame().set_alpha(0.9)

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