#! /usr/bin/env python
# -*- mode:python; coding:utf-8; -*-

#  Calculation of Pi using quadrature.  Using the python-csp package by Sarah Mount.
#
#  Copyright © 2009–2011 Russel Winder

import time
import multiprocessing

from csp.os_process import process , Channel , Par

def execute ( processCount ) :
    n = 10000000 # 100 times fewer due to speed issues.
    delta = 1.0 / n
    startTime = time.time ( )
    sliceSize = n / processCount
    channel = Channel ( )
    @process
    def calculator ( id ) :
        sum = 0.0
        for i in xrange ( 1 + id * sliceSize ,  ( id + 1 ) * sliceSize + 1 ) :
            x = ( i - 0.5 ) * delta
            sum += 1.0 / ( 1.0 + x * x )
        channel.write ( sum )
    @process
    def accumulator ( ) :
        pi = 4.0 * delta * sum ( [ channel.read ( ) for i in xrange ( 0 , processCount ) ] )
        elapseTime = time.time ( ) - startTime
        print ( "==== Python CSP Single NestedShallow pi = " + str ( pi ) )
        print ( "==== Python CSP Single NestedShallow iteration count = " + str ( n ) )
        print ( "==== Python CSP Single NestedShallow elapse = " + str ( elapseTime ) )
        print ( "==== Python CSP Single NestedShallow process count = " + str ( processCount ) )
        print ( "==== Python CSP Single NestedShallow processor count = " + str ( multiprocessing.cpu_count ( ) ) )
    processes = [ ] 
    for i in xrange ( 0 , processCount ) : processes.append ( calculator ( i ) )
    processes.append ( accumulator ( ) )
    Par ( *processes ).start ( )

if __name__ == '__main__' :
    execute ( 1 )
    print
    execute ( 2 )
    print
    execute ( 8 )
    print
    execute ( 32 )