How to avoid repeated recalculation of the same function

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From	pgeipi10@gmail.com
Newsgroups	comp.soft-sys.math.mathematica
Subject	How to avoid repeated recalculation of the same function
Date	Fri, 2 May 2014 06:18:56 +0000 (UTC)
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Hi,

I'm doing a calculaton that's purly symbolic (no graphing, numerical integration, etc.).

Suppose I have a function f[x_]:=... that's very complex to build. In fact, f[x] ends up being a manageable expression (about 30 characters) but it takes Mathematica about 30 min to build that expression.

Another function g[] uses the function f[x] and references it many times. I've discovered that g[] actually builds f[x] every time it's referenced which takes 30 minutes each time. Theoretically, Mathematica could build it once and then use the resulting expression every time it's referenced.

So how do I accomplish that? That is, how do I make it build f[x] once and then use the resulting expression when it's needed?

Thanks,


Pavel

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How to avoid repeated recalculation of the same function pgeipi10@gmail.com - 2014-05-02 06:18 +0000
  Re: How to avoid repeated recalculation of the same function Richard Fateman <fateman@cs.berkeley.edu> - 2014-05-03 07:39 +0000
  Re: How to avoid repeated recalculation of the same function Joe Gwinn <joegwinn@comcast.net> - 2014-05-03 07:40 +0000
  Re: How to avoid repeated recalculation of the same function psycho_dad <s.nesseris@gmail.com> - 2014-05-04 06:27 +0000
  Re: How to avoid repeated recalculation of the same function Roland Franzius <roland.franzius@uos.de> - 2014-05-04 06:28 +0000

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