wfwei/entropy.scala

## entropy.scala
def entropy(x:Double, y:Double):Double = {
    if(x==0 || y==0){
        0
    } else {
        val p1 = x / (x + y)
        val p2 = y / (x + y)
        - (p1*math.log(p1) + p2*math.log(p2))/math.log(2)
    }
}
	def entropy(x:Double, y:Double):Double = {
	if(x==0 \|\| y==0){
	0
	} else {
	val p1 = x / (x + y)
	val p2 = y / (x + y)
	- (p1math.log(p1) + p2math.log(p2))/math.log(2)
	}
	}