# -*- coding: utf-8 -*-
"""
Created on Wed Dec 17 15:08:08 2014

@author: grivet

Listing 5.3 : calcul du polynôme de Wilkinson

"""
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.ticker as mtick

def p(x):
   deg = 12
   pp = 1
   for i in range(1,deg+1):
       pp = pp*(x-i)
   return pp
def q(x,k):
   return p(x) + x**11/2**k
   
x = np.linspace(0.5,12.5,200)
plt.plot(x,p(x),"-k",x,q(x,19),"-r",x,q(x,18),"-g",x,q(x,17),"-b")
plt.ylim(-2e6,2e6)
plt.yticks(np.arange(-2,3)*10**6)
#
#gca() renvoie un pointeur sur le graphique en cours
#
plt.gca().yaxis.set_major_formatter(mtick.FormatStrFormatter('%.1e')) 
plt.title("polynômes de Wilkinson")
plt.show()




#plt.gca().yaxis.set_major_formatter(mtick.FormatStrFormatter('%.0e'))