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66 lines
1.8 KiB
Plaintext
66 lines
1.8 KiB
Plaintext
NAME
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comb - combinatorial number
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SYNOPSIS
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comb(x, y)
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TYPES
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x integer
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y integer
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return integer
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DESCRIPTION
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Return the combinatorial number C(x,y) which is defined as:
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x!
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---------
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y!*(x-y)!
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This function computes the number of combinations in which y things
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may be chosen from x items ignoring the order in which they are chosen.
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EXAMPLE
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; print comb(7,3), comb(7,4), comb(7,5), comb(3,0), comb(0,0)
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35 35 21 1 1
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; print comb(2^31+1,2^31-1)
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2305843010287435776
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LIMITS
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x >= y >= 0
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y < 2^24
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x-y < 2^24
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LINK LIBRARY
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void zcomb(ZVALUE x, ZVALUE y, ZVALUE *res)
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SEE ALSO
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fact, perm, randperm
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## Copyright (C) 1999-2006 Landon Curt Noll
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##
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## Calc is open software; you can redistribute it and/or modify it under
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## the terms of the version 2.1 of the GNU Lesser General Public License
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## as published by the Free Software Foundation.
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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## distributed with calc under the filename COPYING-LGPL. You should have
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
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##
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## @(#) $Revision: 29.4 $
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## @(#) $Id: comb,v 29.4 2006/06/25 22:16:55 chongo Exp $
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## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/comb,v $
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##
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## Under source code control: 1994/10/20 04:03:02
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## File existed as early as: 1994
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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