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71 lines
2.3 KiB
Plaintext
71 lines
2.3 KiB
Plaintext
NAME
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lfactor - smallest prime factor in first specified number of primes
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SYNOPSIS
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lfactor(n, m)
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TYPES
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n integer
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m nonnegative integer <= 203280221 (= number of primes < 2^32)
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return positive integer
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DESCRIPTION
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This function ignores the signs of n and m, so here we shall
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assume n and limit are both nonnegative.
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If n is nonzero and abs(n) has a prime proper factor in the first
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m primes (2, 3, 5, ...), then lfactor(n, m) returns the smallest
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such factor. Otherwise 1 is returned.
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If n is nonzero and m = pix(limit), then lfactor(n, m) returns the
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same as factor(n, limit).
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Both lfactor(n, 0) and lfactor(1, m) return 1 for all n and m.
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Also lfactor(0, m) always returns 1, and factor(0, limit) always
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returns 2 if limit >= 2.
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EXAMPLE
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; print lfactor(35,2), lfactor(35,3), lfactor(-35, 3)
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1 5 5
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; print lfactor(2^32+1,115), lfactor(2^32+1,116), lfactor(2^59-1,1e5)
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1 641 179951
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LIMITS
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m <= 203280221 (= number of primes < 2^32)
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LINK LIBRARY
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NUMBER *qlowfactor(NUMBER *n, NUMBER *count)
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FULL zlowfactor(ZVALUE z, long count)
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SEE ALSO
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factor, isprime, nextcand, nextprime, prevcand, prevprime,
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pfact, pix, ptest
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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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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## @(#) $Revision: 30.1 $
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## @(#) $Id: lfactor,v 30.1 2007/03/16 11:10:42 chongo Exp $
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## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/lfactor,v $
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##
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## Under source code control: 1995/12/18 12:34:57
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## File existed as early as: 1995
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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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