Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Code optimization

  • To: mathgroup at smc.vnet.net
  • Subject: [mg109773] Re: Code optimization
  • From: "M.Roellig" <markus.roellig at googlemail.com>
  • Date: Sun, 16 May 2010 08:51:59 -0400 (EDT)
  • References: <hsofh5$3if$1@smc.vnet.net>

Hi,

Instead of writing

 foo =(expression 1)/(obscenely complex expression )+ (expression 2)/
(obscenely complex expression )

it pays out to do something like :

denominator = obscenely complex expression ;

foo=(expression 1)/denominator + (expression 2)/denominator

Mathematica will calculate the complex expression once and store the
result in denominator
and only use that for later occurances of denominator.

If you use

denominator := obscenely complex expression ;

instead, it will recalculate the complex stuff each time denominator
is encountered.

Markus


>
> foo =(expression 1)/denominator + (expression 2)/denominator
>
> where "denominator" is itself a complex expression. Is it worthwhile for
> me to compute "denominator" once and use it explicitly in foo, or will
> Mathematica cleverly deduce that it needs to be computed only once?
>
> My guess is that Mathematica is an interpreter so it will not optimize the code.
>
> Steve Gray


  • Prev by Date: Re: Latex, Mathematica, and journals
  • Next by Date: Re: Latex, Mathematica, and journals
  • Previous by thread: Code optimization
  • Next by thread: Re: Code optimization