- To: mathgroup at smc.vnet.net
- Subject: [mg62421] Re: permutations
- From: "Scout" <Scout at nodomain.com>
- Date: Thu, 24 Nov 2005 06:33:20 -0500 (EST)
- References: <email@example.com>
- Sender: owner-wri-mathgroup at wolfram.com
"Francisco Gutierrez" <fgutiers2002 at yahoo.com>
> Dear Group:
> If I do for example:
> my computer runs out of memory.
> This is not such a poor computer. Actually, I would need to do
> permutations of lists of Length 20, perhaps 25. I am aware these
> calculations are big (Length[x]!), but I wonder if there is some way
> around the problem. Compilating Permutations? But then how? Can somebody
> help me?
> Francisco Gutiérrez
have you already tried to use the NextPermutation function?
NextPermutations[ l ] gives
that differ from the previous list in only one change.
So, applying repeatedly NextPermutation you can cover
all the Length[l]! permutations.
I hope this help you,
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