#import matplotlib.pyplot as plt



def npi(n,x,y):
    m = [[0.0 for i in range(n)] for j in range(n+1)]
    print m
    m[0]=x
    m[1]=y
    print m
    for i in range(0,n):
        for j in range(i,n-1):
            print i,j
            print m[2+i-1][j+1]
            print m[2+i-1][j]
            print m[0][j+1]
            print m[0][j-i]

            m[2+i][j+1]=(m[2+i-1][j+1]-m[2+i-1][j])/(m[0][j+1]-m[0][j-i])
            print m[2+i][j+1]
            print "---"


   #plt.plot([1, 2, 3, 4], [1, 4, 9, 16])

    #plt.show()

print "hello"
npi(3,[-1.0,0.0,2.0],[0.5,1.0,4.0])