What is faster x**.5 or math.sqrt(x) in Python?

.gitignore

.tox/
/MANIFEST

claudiu.py

#!/usr/bin/env python
#http://stackoverflow.com/questions/327002/which-is-faster-in-python-x-5-or-math-sqrtx/327011#327011
import math

from timeit import default_timer as timer

try: xrange = xrange
except NameError:
    xrange = range # py3k

def timeit1():
    s = timer()
    for i in xrange(750000):
        z = i**.5
    print("Took %f seconds" % (timer() - s))

def timeit2(arg=math.sqrt):
    s = timer()
    for i in xrange(750000):
        z = arg(i)
    print("Took %f seconds" % (timer() - s))

timeit1()
timeit2()

# Results produced on machine:

# $ uname -vms
# Linux #42-Ubuntu SMP Thu Dec 2 02:41:37 UTC 2010 x86_64
# $ cat /proc/cpuinfo | grep 'model name' | head -1
# model name      : Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz

# | Interpreter    |  x**.5, |   sqrt, | sqrt faster, % |
# |                | seconds | seconds |                |
# |----------------+---------+---------+----------------|
# | Python 3.2rc1+ |    0.32 |    0.27 |             19 |
# | Python 3.1.2   |   0.136 |   0.088 |             55 |
# | Python 3.0.1   |   0.155 |   0.102 |             52 |
# | Python 2.7     |   0.132 |   0.079 |             67 |
# | Python 2.6.6   |   0.121 |   0.075 |             61 |
# | PyPy 1.4.1     |   0.083 |  0.0159 |            422 |
# | Jython 2.5.1   |   0.132 |    0.22 |            -40 |
# | Python 2.5.5   |   0.129 |   0.125 |              3 |
# | Python 2.4.6   |   0.131 |   0.123 |              7 |
##+TBLFM: $4=100*($2-$3)/$3;%.0f

# To reproduce results:

# * get source: [`git clone git://gist.github.com/783011.git gist-783011`][1]
# * install [`tox`][2]: `pip install tox`
# * run `tox` from the directory with `tox.ini` file.


#   [1]: https://gist.github.com/783011
#   [2]: http://codespeak.net/tox/

setup.py

"""Dummy file to satisfy `tox`."""
from distutils.core import setup

NAME             = 'dummy-package-for-tox'
VERSION          = '0.0.1'
LICENSE          = 'MIT'
AUTHOR           = "me"
AUTHOR_EMAIL     = "me@laptop"

setup(
    name=NAME,
    version=VERSION,
    license=LICENSE,
    author=AUTHOR,
    author_email=AUTHOR_EMAIL,
    maintainer=AUTHOR,
    maintainer_email=AUTHOR_EMAIL,
)

tox.ini

[tox]
envlist = py32,py31,py30,py27,py26,pypy,jython,py25,py24

[testenv]
commands=
    python -V
    python claudiu.py

[testenv:pypy]
basepython=pypy

[testenv:jython]
commands=
    jython -V
    jython claudiu.py