Scalaで素数判定その３

PrimeNum.scala

import scala.math.sqrt
 
object PrimeNum {
 
  def main(args:Array[String]) {
    val num:Long = args(0).toLong
 
    if(isPrime(num)) println(num + " is Prime Number.")
    else println(num + " is NOT Prime Number.")
  }
 
  def isPrime(num:Long):Boolean = {
    if (num == 1 || num%2==0) {
      false
    } else {
      (3L to sqrt(num).toLong by 2).forall {
        e => num%e != 0
      }
    }
  }