import math


def computeProb(i, j, lf, le, lamb):
	"""

	Compute numerator

	i,j : int
	alignment of word i to j

	lf, le: int
	length of target sentence(lf) and source sentence(le)

	lamb: float
	Hyper parameters, currently set to be 4.0
	
	"""
	h = -1.0 * abs( float(j) / float(le) - float(i) / float(lf))
	return math.exp(h * lamb)