lcm.c
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上传日期:2022-08-06
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- /* mpz_lcm -- mpz/mpz least common multiple.
- Copyright 1996, 2000, 2001, 2005 Free Software Foundation, Inc.
- This file is part of the GNU MP Library.
- The GNU MP Library is free software; you can redistribute it and/or modify
- it under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 3 of the License, or (at your
- option) any later version.
- The GNU MP Library 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.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include "gmp.h"
- #include "gmp-impl.h"
- #include "longlong.h"
- void
- mpz_lcm (mpz_ptr r, mpz_srcptr u, mpz_srcptr v)
- {
- mpz_t g;
- mp_size_t usize, vsize, size;
- TMP_DECL;
- usize = SIZ (u);
- vsize = SIZ (v);
- if (usize == 0 || vsize == 0)
- {
- SIZ (r) = 0;
- return;
- }
- usize = ABS (usize);
- vsize = ABS (vsize);
- if (vsize == 1)
- {
- mp_limb_t vl, gl, c;
- mp_srcptr up;
- mp_ptr rp;
- one:
- MPZ_REALLOC (r, usize+1);
- up = PTR(u);
- vl = PTR(v)[0];
- gl = mpn_gcd_1 (up, usize, vl);
- vl /= gl;
- rp = PTR(r);
- c = mpn_mul_1 (rp, up, usize, vl);
- rp[usize] = c;
- usize += (c != 0);
- SIZ(r) = usize;
- return;
- }
- if (usize == 1)
- {
- usize = vsize;
- MPZ_SRCPTR_SWAP (u, v);
- goto one;
- }
- TMP_MARK;
- size = MAX (usize, vsize);
- MPZ_TMP_INIT (g, size);
- mpz_gcd (g, u, v);
- mpz_divexact (g, u, g);
- mpz_mul (r, g, v);
- SIZ (r) = ABS (SIZ (r)); /* result always positive */
- TMP_FREE;
- }