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Re: Simplify and Memory

  • To: mathgroup at
  • Subject: [mg58241] Re: [mg58216] Simplify and Memory
  • From: Daniel Lichtblau <danl at>
  • Date: Fri, 24 Jun 2005 02:50:00 -0400 (EDT)
  • References: <>
  • Sender: owner-wri-mathgroup at

Geraud wrote:
> Hi Group
> I have a list of complicated expressions ExprList={expr1,expr2,...} and 
> I try to (Full)Simplify them.
> If I apply (Full)Simplify to ExprList or to each of the expressions 
> inside (in a Do[] loop), the kernel goes out of memory (2 GB PIV computer).
> However if I save the expressions in a file and I simplify each 
> expression one after the other, quitting the kernel at each step, it works.
> It seems that Mathematica keeps in memory a lot of information about 
> past simplification processes. It is useful for saving time (try to 
> simplify two similar expressions), but very expensive as far as memory 
> is concerned.
> "Clear[Out]" or "Share[expr]" at each step does not help.
> How can I delete the memory associated with Simplify at each step, 
> rather than quitting the kernel and doing the loop by hand ?
> Thanks a lot.
> G.

Some amount of memory, perhaps a lot, is used in caching intermediate 
results. It can be freed by doing Developer`ClearCache[]. Obviously 
whether this is adequate is a very problem specific matter. Certainly it 
is worth a try.

Daniel Lichtblau
Wolfram Research

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