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Re: combinations
- To: "Czerminski, Ryszard" <ryszard at arqule dot com>
- Subject: Re: combinations
- From: Brian Gough <bjg at network-theory dot co dot uk>
- Date: Sun, 26 Sep 1999 23:33:30 +0100 (BST)
- Cc: "'gsl-discuss at sourceware dot cygnus dot com'" <gsl-discuss at sourceware dot cygnus dot com>
- References: <6B00FB949906D211A88800104B8AE520F419F6@WIREHEAD>
I'm not aware of any routines apart from the one you mention (in TOMS
on netlib), but I'm no expert in that area so there may be others.
Czerminski, Ryszard writes:
> I am looking for a function which could compute
> combinations given lexicographical index e.g.
>
> C(1;3,2) -> 1,2
> C(2;3,2) -> 1,3
> C(3;3,2) -> 2,3
>
> I have found function which does this
> ( http://math.nist.gov/GAMS.html ) but it is limited
> to small numbers since it is using regular 4 bytes
> representation for integers and therefore index
> range is severly limited ( < 2^32 ).
>
> Any pointers to the software which does this for
> integers of arbitrary length would be very much
> appreciated.
>
> Ryszard Czerminski phone: (781)395-1269 x 479
> ArQule, Inc. e-mail: ryszard@arqule.com
> 200 Boston Avenue http://www.arqule.com
> Medford, MA 02155