1  #
       2  # Copyright (C) 2001-2012 Python Software Foundation. All Rights Reserved.
       3  # Modified and extended by Stefan Krah.
       4  #
       5  
       6  # Usage: ../../../python bench.py
       7  
       8  
       9  import time
      10  from test.support.import_helper import import_fresh_module
      11  
      12  C = import_fresh_module('decimal', fresh=['_decimal'])
      13  P = import_fresh_module('decimal', blocked=['_decimal'])
      14  
      15  #
      16  # NOTE: This is the pi function from the decimal documentation, modified
      17  # for benchmarking purposes. Since floats do not have a context, the higher
      18  # intermediate precision from the original is NOT used, so the modified
      19  # algorithm only gives an approximation to the correctly rounded result.
      20  # For serious use, refer to the documentation or the appropriate literature.
      21  #
      22  def pi_float():
      23      """native float"""
      24      lasts, t, s, n, na, d, da = 0, 3.0, 3, 1, 0, 0, 24
      25      while s != lasts:
      26          lasts = s
      27          n, na = n+na, na+8
      28          d, da = d+da, da+32
      29          t = (t * n) / d
      30          s += t
      31      return s
      32  
      33  def pi_cdecimal():
      34      """cdecimal"""
      35      D = C.Decimal
      36      lasts, t, s, n, na, d, da = D(0), D(3), D(3), D(1), D(0), D(0), D(24)
      37      while s != lasts:
      38          lasts = s
      39          n, na = n+na, na+8
      40          d, da = d+da, da+32
      41          t = (t * n) / d
      42          s += t
      43      return s
      44  
      45  def pi_decimal():
      46      """decimal"""
      47      D = P.Decimal
      48      lasts, t, s, n, na, d, da = D(0), D(3), D(3), D(1), D(0), D(0), D(24)
      49      while s != lasts:
      50          lasts = s
      51          n, na = n+na, na+8
      52          d, da = d+da, da+32
      53          t = (t * n) / d
      54          s += t
      55      return s
      56  
      57  def factorial(n, m):
      58      if (n > m):
      59          return factorial(m, n)
      60      elif m == 0:
      61          return 1
      62      elif n == m:
      63          return n
      64      else:
      65          return factorial(n, (n+m)//2) * factorial((n+m)//2 + 1, m)
      66  
      67  
      68  print("\n# ======================================================================")
      69  print("#                   Calculating pi, 10000 iterations")
      70  print("# ======================================================================\n")
      71  
      72  to_benchmark = [pi_float, pi_decimal]
      73  if C is not None:
      74      to_benchmark.insert(1, pi_cdecimal)
      75  
      76  for prec in [9, 19]:
      77      print("\nPrecision: %d decimal digits\n" % prec)
      78      for func in to_benchmark:
      79          start = time.time()
      80          if C is not None:
      81              C.getcontext().prec = prec
      82          P.getcontext().prec = prec
      83          for i in range(10000):
      84              x = func()
      85          print("%s:" % func.__name__.replace("pi_", ""))
      86          print("result: %s" % str(x))
      87          print("time: %fs\n" % (time.time()-start))
      88  
      89  
      90  print("\n# ======================================================================")
      91  print("#                               Factorial")
      92  print("# ======================================================================\n")
      93  
      94  if C is not None:
      95      c = C.getcontext()
      96      c.prec = C.MAX_PREC
      97      c.Emax = C.MAX_EMAX
      98      c.Emin = C.MIN_EMIN
      99  
     100  for n in [100000, 1000000]:
     101  
     102      print("n = %d\n" % n)
     103  
     104      if C is not None:
     105          # C version of decimal
     106          start_calc = time.time()
     107          x = factorial(C.Decimal(n), 0)
     108          end_calc = time.time()
     109          start_conv = time.time()
     110          sx = str(x)
     111          end_conv = time.time()
     112          print("cdecimal:")
     113          print("calculation time: %fs" % (end_calc-start_calc))
     114          print("conversion time: %fs\n" % (end_conv-start_conv))
     115  
     116      # Python integers
     117      start_calc = time.time()
     118      y = factorial(n, 0)
     119      end_calc = time.time()
     120      start_conv = time.time()
     121      sy = str(y)
     122      end_conv =  time.time()
     123  
     124      print("int:")
     125      print("calculation time: %fs" % (end_calc-start_calc))
     126      print("conversion time: %fs\n\n" % (end_conv-start_conv))
     127  
     128      if C is not None:
     129          assert(sx == sy)