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53 lines
1.4 KiB
Plaintext
53 lines
1.4 KiB
Plaintext
/*
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* pollard - factor using Pollard's p-1 method
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*
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* Copyright (C) 1999 David I. Bell
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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: 29.2 $
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* @(#) $Id: pollard.cal,v 29.2 2000/06/07 14:02:25 chongo Exp $
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* @(#) $Source: /usr/local/src/cmd/calc/cal/RCS/pollard.cal,v $
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*
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* Under source code control: 1991/05/22 21:56:37
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* File existed as early as: 1991
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*
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* Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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*/
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define pfactor(N, B, ai, af)
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{
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local a, k, i, d;
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if (isnull(B))
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B = 1000;
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if (isnull(ai))
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ai = 2;
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if (isnull(af))
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af = ai + 20;
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k = lcmfact(B);
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d = lfactor(N, B);
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if (d > 1)
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return d;
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for (a = ai; a <= af; a++) {
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i = pmod(a, k, N);
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d = gcd(i - 1, N);
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if ((d > 1) && (d != N))
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return d;
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}
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return 1;
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}
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