def rankingEval(self):
		'''
		Sorting the pop. base on the fitnessEval result
		'''
		fitnessAll = numpy.zeros(self.length)
		fitnessNorm = numpy.zeros(self.length)
		for i in range(self.length):
			self.Ind[i].fitnessEval()
			fitnessAll[i] = self.Ind[i].fitness
		maxFitness = fitnessAll.max()
		for i in range(self.length):
			fitnessNorm[i] = (maxFitness - fitnessAll[i]) / maxFitness
		fitnessSorted = fitnessNorm.argsort()
		probability = numpy.zeros(self.length)
		S = 2.0
		for i in range(self.length):
			probability[fitnessSorted[i]] = ((2-S)/self.length) + (2*i*(S-1))/(self.length*(self.length-1))
		self.rankingComputed = 1
		self.fitness = 	fitnessAll
		return [fitnessAll, fitnessSorted[::-1], probability]