| Austin Schuh | dace2a6 | 2020-08-18 10:56:48 -0700 | [diff] [blame] | 1 | /* mpz_lcm -- mpz/mpz least common multiple. |
| 2 | |
| 3 | Copyright 1996, 2000, 2001, 2005, 2012 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of the GNU MP Library. |
| 6 | |
| 7 | The GNU MP Library is free software; you can redistribute it and/or modify |
| 8 | it under the terms of either: |
| 9 | |
| 10 | * the GNU Lesser General Public License as published by the Free |
| 11 | Software Foundation; either version 3 of the License, or (at your |
| 12 | option) any later version. |
| 13 | |
| 14 | or |
| 15 | |
| 16 | * the GNU General Public License as published by the Free Software |
| 17 | Foundation; either version 2 of the License, or (at your option) any |
| 18 | later version. |
| 19 | |
| 20 | or both in parallel, as here. |
| 21 | |
| 22 | The GNU MP Library is distributed in the hope that it will be useful, but |
| 23 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 24 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 25 | for more details. |
| 26 | |
| 27 | You should have received copies of the GNU General Public License and the |
| 28 | GNU Lesser General Public License along with the GNU MP Library. If not, |
| 29 | see https://www.gnu.org/licenses/. */ |
| 30 | |
| 31 | #include "gmp-impl.h" |
| 32 | |
| 33 | void |
| 34 | mpz_lcm (mpz_ptr r, mpz_srcptr u, mpz_srcptr v) |
| 35 | { |
| 36 | mpz_t g; |
| 37 | mp_size_t usize, vsize; |
| 38 | TMP_DECL; |
| 39 | |
| 40 | usize = SIZ (u); |
| 41 | vsize = SIZ (v); |
| 42 | if (usize == 0 || vsize == 0) |
| 43 | { |
| 44 | SIZ (r) = 0; |
| 45 | return; |
| 46 | } |
| 47 | usize = ABS (usize); |
| 48 | vsize = ABS (vsize); |
| 49 | |
| 50 | if (vsize == 1 || usize == 1) |
| 51 | { |
| 52 | mp_limb_t vl, gl, c; |
| 53 | mp_srcptr up; |
| 54 | mp_ptr rp; |
| 55 | |
| 56 | if (usize == 1) |
| 57 | { |
| 58 | usize = vsize; |
| 59 | MPZ_SRCPTR_SWAP (u, v); |
| 60 | } |
| 61 | |
| 62 | MPZ_REALLOC (r, usize+1); |
| 63 | |
| 64 | up = PTR(u); |
| 65 | vl = PTR(v)[0]; |
| 66 | gl = mpn_gcd_1 (up, usize, vl); |
| 67 | vl /= gl; |
| 68 | |
| 69 | rp = PTR(r); |
| 70 | c = mpn_mul_1 (rp, up, usize, vl); |
| 71 | rp[usize] = c; |
| 72 | usize += (c != 0); |
| 73 | SIZ(r) = usize; |
| 74 | return; |
| 75 | } |
| 76 | |
| 77 | TMP_MARK; |
| 78 | MPZ_TMP_INIT (g, usize); /* v != 0 implies |gcd(u,v)| <= |u| */ |
| 79 | |
| 80 | mpz_gcd (g, u, v); |
| 81 | mpz_divexact (g, u, g); |
| 82 | mpz_mul (r, g, v); |
| 83 | |
| 84 | SIZ (r) = ABS (SIZ (r)); /* result always positive */ |
| 85 | |
| 86 | TMP_FREE; |
| 87 | } |