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Re: How can I make this piece of code even faster?

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El domingo, 21 de julio de 2013 12:31:42 UTC+2, Steven D'Aprano  escribió:
> On Sun, 21 Jul 2013 03:19:24 -0700, pablobarhamalzas wrote:
> 
> 
> 
> > Thank's for all the replies! I've tried some of the imporovements you
> 
> > suggested (using math.exp() and sum() or math.fsum()). None of that made
> 
> > the code faster, because they are functions you are calling lots of
> 
> > times, and function calling is quite time expensive (same as x**(1/2) is
> 
> > faster than math.sqrt(x)).
> 
> 
> 
> You are *badly* mistaken. Not only is sqrt more accurate, but it is also 
> 
> much faster.
> 
> 
> 
> 
> 
> [steve@ando ~]$ python3.3 -m timeit -s "x = 2.357e7" "x**0.5"
> 
> 1000000 loops, best of 3: 0.319 usec per loop
> 
> [steve@ando ~]$ python3.3 -m timeit -s "x = 2.357e7" -s "from math import 
> 
> sqrt" "sqrt(x)"
> 
> 10000000 loops, best of 3: 0.172 usec per loop
> 
> 
> 
> 
> 
> How exactly are you timing the code?

I'm timing the whole program with cProfile. Removing math.sqrt() from a function and using **(1/2) instead cut the execution time for a significant amount (~0.035 to ~0.020). I can't see another explanation for the speed increase...

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How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-20 13:22 -0700
  Re: How can I make this piece of code even faster? Fabio Zadrozny <fabiofz@gmail.com> - 2013-07-20 18:05 -0300
  Re: How can I make this piece of code even faster? Roy Smith <roy@panix.com> - 2013-07-20 17:25 -0400
  Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-20 15:45 -0700
  Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 08:55 +1000
  Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-20 16:24 -0700
    Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 09:29 +1000
  Re: How can I make this piece of code even faster? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-21 05:11 +0000
    Re: How can I make this piece of code even faster? Paul Rudin <paul.nospam@rudin.co.uk> - 2013-07-21 08:11 +0100
      Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 19:21 +1000
  Re: How can I make this piece of code even faster? Peter Otten <__peter__@web.de> - 2013-07-21 09:10 +0200
  Re: How can I make this piece of code even faster? Serhiy Storchaka <storchaka@gmail.com> - 2013-07-21 10:11 +0300
  Re: How can I make this piece of code even faster? Christian Gollwitzer <auriocus@gmx.de> - 2013-07-21 09:24 +0200
  Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-21 03:19 -0700
    Re: How can I make this piece of code even faster? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-21 10:31 +0000
      Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-21 03:48 -0700
        Re: How can I make this piece of code even faster? Stefan Behnel <stefan_ml@behnel.de> - 2013-07-21 14:49 +0200
      Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 20:48 +1000
    Re: How can I make this piece of code even faster? Michael Torrie <torriem@gmail.com> - 2013-07-21 09:27 -0600
  Re: How can I make this piece of code even faster? Joshua Landau <joshua@landau.ws> - 2013-07-21 12:39 +0100

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