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author | Pasha <pasha@member.fsf.org> | 2023-01-27 00:54:07 +0000 |
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committer | Pasha <pasha@member.fsf.org> | 2023-01-27 00:54:07 +0000 |
commit | ef800d4ffafdbde7d7a172ad73bd984b1695c138 (patch) | |
tree | 920cc189130f1e98f252283fce94851443641a6d /glpk-5.0/src/misc/gcd.c | |
parent | ec4ae3c2b5cb0e83fb667f14f832ea94f68ef075 (diff) | |
download | oneapi-ef800d4ffafdbde7d7a172ad73bd984b1695c138.tar.gz oneapi-ef800d4ffafdbde7d7a172ad73bd984b1695c138.tar.bz2 |
Diffstat (limited to 'glpk-5.0/src/misc/gcd.c')
-rw-r--r-- | glpk-5.0/src/misc/gcd.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/glpk-5.0/src/misc/gcd.c b/glpk-5.0/src/misc/gcd.c new file mode 100644 index 0000000..78a4e51 --- /dev/null +++ b/glpk-5.0/src/misc/gcd.c @@ -0,0 +1,100 @@ +/* gcd.c (greatest common divisor) */ + +/*********************************************************************** +* This code is part of GLPK (GNU Linear Programming Kit). +* Copyright (C) 2000 Free Software Foundation, Inc. +* Written by Andrew Makhorin <mao@gnu.org>. +* +* GLPK is free software: you can redistribute it and/or modify it +* under the terms of the GNU General Public License as published by +* the Free Software Foundation, either version 3 of the License, or +* (at your option) any later version. +* +* GLPK 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 General Public +* License for more details. +* +* You should have received a copy of the GNU General Public License +* along with GLPK. If not, see <http://www.gnu.org/licenses/>. +***********************************************************************/ + +#include "env.h" +#include "misc.h" + +/*********************************************************************** +* NAME +* +* gcd - find greatest common divisor of two integers +* +* SYNOPSIS +* +* #include "misc.h" +* int gcd(int x, int y); +* +* RETURNS +* +* The routine gcd returns gcd(x, y), the greatest common divisor of +* the two positive integers given. +* +* ALGORITHM +* +* The routine gcd is based on Euclid's algorithm. +* +* REFERENCES +* +* Don Knuth, The Art of Computer Programming, Vol.2: Seminumerical +* Algorithms, 3rd Edition, Addison-Wesley, 1997. Section 4.5.2: The +* Greatest Common Divisor, pp. 333-56. */ + +int gcd(int x, int y) +{ int r; + xassert(x > 0 && y > 0); + while (y > 0) + r = x % y, x = y, y = r; + return x; +} + +/*********************************************************************** +* NAME +* +* gcdn - find greatest common divisor of n integers +* +* SYNOPSIS +* +* #include "misc.h" +* int gcdn(int n, int x[]); +* +* RETURNS +* +* The routine gcdn returns gcd(x[1], x[2], ..., x[n]), the greatest +* common divisor of n positive integers given, n > 0. +* +* BACKGROUND +* +* The routine gcdn is based on the following identity: +* +* gcd(x, y, z) = gcd(gcd(x, y), z). +* +* REFERENCES +* +* Don Knuth, The Art of Computer Programming, Vol.2: Seminumerical +* Algorithms, 3rd Edition, Addison-Wesley, 1997. Section 4.5.2: The +* Greatest Common Divisor, pp. 333-56. */ + +int gcdn(int n, int x[]) +{ int d, j; + xassert(n > 0); + for (j = 1; j <= n; j++) + { xassert(x[j] > 0); + if (j == 1) + d = x[1]; + else + d = gcd(d, x[j]); + if (d == 1) + break; + } + return d; +} + +/* eof */ |