Calculates the probability of a distribution of multidimensional stocastic variables (binominal distrubution).

MultiDimBin.scala

package probability
import scala.math
/***
 * Calculates the probability of a distribution of multidimensional stocastic variables (binominal distrubution). 
 * 
 * param n: number of events
 * param probabilityList: Array of the probabilites of the different event
 * param occurance: Array of number of occurances we want to know the probability of
 *   
 * called with i.e. multidimensionalBinProb(12, Array(0.5, 0.5), Array(6,6))
 */
object utils {
	def factorial(number : Int) : Int = {
	    number match {
	        case 1 => 1
	        case 0 => 0
	        case x if x < 0 => throw new IllegalArgumentException("Only values larger than 0")
	        case _ => number * factorial(number - 1)
	    }
	}
	
	def multidimensionalBinProb(n: Int, probabilityList : Array[Double], occurance : Array[Int]) : Double = {
		assert(probabilityList.length == occurance.length, println("Not of equal length"))
		val totalK : Double = occurance.map(factorial(_)).foldLeft(1)(_*_) 
		var probList : Array[Double] = Array()
		for (i <- 0 until probabilityList.length) probList = probList :+ math.pow(probabilityList(i),occurance(i)) 
		val totalProb = probList.foldLeft(1.0)(_*_)
		(factorial(n) / totalK ) * totalProb
	}
	def main(string : Array[String]) {
	    println(multidimensionalBinProb(12, Array(0.5, 0.5), Array(6,6)))
	}
}