mul.c
上传用户:qaz666999
上传日期:2022-08-06
资源大小:2570k
文件大小:3k
- /* mpq_mul -- multiply two rational numbers.
- Copyright 1991, 1994, 1995, 1996, 2000, 2001, 2002 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"
- void
- mpq_mul (mpq_ptr prod, mpq_srcptr op1, mpq_srcptr op2)
- {
- mpz_t gcd1, gcd2;
- mpz_t tmp1, tmp2;
- mp_size_t op1_num_size;
- mp_size_t op1_den_size;
- mp_size_t op2_num_size;
- mp_size_t op2_den_size;
- mp_size_t alloc;
- TMP_DECL;
- if (op1 == op2)
- {
- /* No need for any GCDs when squaring. */
- mpz_mul (mpq_numref (prod), mpq_numref (op1), mpq_numref (op1));
- mpz_mul (mpq_denref (prod), mpq_denref (op1), mpq_denref (op1));
- return;
- }
- op1_num_size = ABS (op1->_mp_num._mp_size);
- op1_den_size = op1->_mp_den._mp_size;
- op2_num_size = ABS (op2->_mp_num._mp_size);
- op2_den_size = op2->_mp_den._mp_size;
- if (op1_num_size == 0 || op2_num_size == 0)
- {
- /* We special case this to simplify allocation logic; gcd(0,x) = x
- is a singular case for the allocations. */
- prod->_mp_num._mp_size = 0;
- prod->_mp_den._mp_d[0] = 1;
- prod->_mp_den._mp_size = 1;
- return;
- }
- TMP_MARK;
- alloc = MIN (op1_num_size, op2_den_size);
- MPZ_TMP_INIT (gcd1, alloc);
- alloc = MIN (op2_num_size, op1_den_size);
- MPZ_TMP_INIT (gcd2, alloc);
- alloc = MAX (op1_num_size, op2_den_size);
- MPZ_TMP_INIT (tmp1, alloc);
- alloc = MAX (op2_num_size, op1_den_size);
- MPZ_TMP_INIT (tmp2, alloc);
- /* PROD might be identical to either operand, so don't store the result there
- until we are finished with the input operands. We can overwrite the
- numerator of PROD when we are finished with the numerators of OP1 and
- OP2. */
- mpz_gcd (gcd1, &(op1->_mp_num), &(op2->_mp_den));
- mpz_gcd (gcd2, &(op2->_mp_num), &(op1->_mp_den));
- mpz_divexact_gcd (tmp1, &(op1->_mp_num), gcd1);
- mpz_divexact_gcd (tmp2, &(op2->_mp_num), gcd2);
- mpz_mul (&(prod->_mp_num), tmp1, tmp2);
- mpz_divexact_gcd (tmp1, &(op2->_mp_den), gcd1);
- mpz_divexact_gcd (tmp2, &(op1->_mp_den), gcd2);
- mpz_mul (&(prod->_mp_den), tmp1, tmp2);
- TMP_FREE;
- }