/*
 *  Calculation of Pi using quadrature realized with a basic sequential algorithm using a for "loop".
 *
 *  Copyright © 2009–2011 Russel Winder
 */

//  When using the idiom of extending Application to create a main procedure, variables are represented as
//  methods and this means performance seriously plummets.  The idiom must therefore be to only have
//  function calls in the main sequence.  cf. Pi_Scala_Sequential.scala.

object Pi_Scala_Sequential_Application_Alt extends App {
  def doStuff ( ) = {
    val n = 1000000000
    val delta = 1.0 / n
    val startTimeNanos = System.nanoTime
    var sum = 0.0
    for ( i <- 1 to n ) {
      val x = ( i - 0.5 ) * delta
      sum += 1.0 / ( 1.0 + x * x )
    }
    val pi = 4.0 * delta * sum
    def elapseTime = ( System.nanoTime - startTimeNanos ) / 1e9
    println ( "==== Scala Sequential Application Alt pi = " + pi )
    println ( "==== Scala Sequential Application Alt iteration count = " + n )
    println ( "==== Scala Sequential Applciation Alt elapse = " + elapseTime )
  }
  doStuff ( )
}