NAME lfactor - smallest prime factor in first specified number of primes SYNOPSIS lfactor(n, m) TYPES n integer m nonnegative integer <= 203280221 (= number of primes < 2^32) return positive integer DESCRIPTION This function ignores the signs of n and m, so here we shall assume n and limit are both nonnegative. If n is nonzero and abs(n) has a prime proper factor in the first m primes (2, 3, 5, ...), then lfactor(n, m) returns the smallest such factor. Otherwise 1 is returned. If n is nonzero and m = pix(limit), then lfactor(n, m) returns the same as factor(n, limit). Both lfactor(n, 0) and lfactor(1, m) return 1 for all n and m. Also lfactor(0, m) always returns 1, and factor(0, limit) always returns 2 if limit >= 2. EXAMPLE ; print lfactor(35,2), lfactor(35,3), lfactor(-35, 3) 1 5 5 ; print lfactor(2^32+1,115), lfactor(2^32+1,116), lfactor(2^59-1,1e5) 1 641 179951 LIMITS m <= 203280221 (= number of primes < 2^32) LINK LIBRARY NUMBER *qlowfactor(NUMBER *n, NUMBER *count) FULL zlowfactor(ZVALUE z, long count) SEE ALSO factor, isprime, nextcand, nextprime, prevcand, prevprime, pfact, pix, ptest ## Copyright (C) 1999-2006 Landon Curt Noll ## ## Calc is open software; you can redistribute it and/or modify it under ## the terms of the version 2.1 of the GNU Lesser General Public License ## as published by the Free Software Foundation. ## ## Calc is distributed in the hope that it will be useful, but WITHOUT ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY ## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General ## Public License for more details. ## ## A copy of version 2.1 of the GNU Lesser General Public License is ## distributed with calc under the filename COPYING-LGPL. You should have ## received a copy with calc; if not, write to Free Software Foundation, Inc. ## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. ## ## @(#) $Revision: 30.1 $ ## @(#) $Id: lfactor,v 30.1 2007/03/16 11:10:42 chongo Exp $ ## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/lfactor,v $ ## ## Under source code control: 1995/12/18 12:34:57 ## File existed as early as: 1995 ## ## chongo /\oo/\ http://www.isthe.com/chongo/ ## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/