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Annotation of OpenXM_contrib/gmp/mpq/mul.c, Revision 1.1

1.1     ! maekawa     1: /* mpq_mul -- mutiply two rational numbers.
        !             2:
        !             3: Copyright (C) 1991, 1994, 1995, 1996 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 the GNU Library General Public License as published by
        !             9: the Free Software Foundation; either version 2 of the License, or (at your
        !            10: option) any later version.
        !            11:
        !            12: The GNU MP Library is distributed in the hope that it will be useful, but
        !            13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Library General Public License
        !            18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            20: MA 02111-1307, USA. */
        !            21:
        !            22: #include "gmp.h"
        !            23: #include "gmp-impl.h"
        !            24:
        !            25: void
        !            26: #if __STDC__
        !            27: mpq_mul (mpq_ptr prod, mpq_srcptr op1, mpq_srcptr op2)
        !            28: #else
        !            29: mpq_mul (prod, op1, op2)
        !            30:      mpq_ptr prod;
        !            31:      mpq_srcptr op1;
        !            32:      mpq_srcptr op2;
        !            33: #endif
        !            34: {
        !            35:   mpz_t gcd1, gcd2;
        !            36:   mpz_t tmp1, tmp2;
        !            37:
        !            38:   mpz_init (gcd1);
        !            39:   mpz_init (gcd2);
        !            40:   mpz_init (tmp1);
        !            41:   mpz_init (tmp2);
        !            42:
        !            43:   /* PROD might be identical to either operand, so don't store the
        !            44:      result there until we are finished with the input operands.  We
        !            45:      dare to overwrite the numerator of PROD when we are finished
        !            46:      with the numerators of OP1 and OP2.  */
        !            47:
        !            48:   mpz_gcd (gcd1, &(op1->_mp_num), &(op2->_mp_den));
        !            49:   mpz_gcd (gcd2, &(op2->_mp_num), &(op1->_mp_den));
        !            50:
        !            51:   if (gcd1->_mp_size > 1 || gcd1->_mp_d[0] != 1)
        !            52:     mpz_divexact (tmp1, &(op1->_mp_num), gcd1);
        !            53:   else
        !            54:     mpz_set (tmp1, &(op1->_mp_num));
        !            55:
        !            56:   if (gcd2->_mp_size > 1 || gcd2->_mp_d[0] != 1)
        !            57:     mpz_divexact (tmp2, &(op2->_mp_num), gcd2);
        !            58:   else
        !            59:     mpz_set (tmp2, &(op2->_mp_num));
        !            60:
        !            61:   mpz_mul (&(prod->_mp_num), tmp1, tmp2);
        !            62:
        !            63:   if (gcd1->_mp_size > 1 || gcd1->_mp_d[0] != 1)
        !            64:     mpz_divexact (tmp1, &(op2->_mp_den), gcd1);
        !            65:   else
        !            66:     mpz_set (tmp1, &(op2->_mp_den));
        !            67:
        !            68:   if (gcd2->_mp_size > 1 || gcd2->_mp_d[0] != 1)
        !            69:     mpz_divexact (tmp2, &(op1->_mp_den), gcd2);
        !            70:   else
        !            71:     mpz_set (tmp2, &(op1->_mp_den));
        !            72:
        !            73:   mpz_mul (&(prod->_mp_den), tmp1, tmp2);
        !            74:
        !            75:   mpz_clear (tmp2);
        !            76:   mpz_clear (tmp1);
        !            77:   mpz_clear (gcd2);
        !            78:   mpz_clear (gcd1);
        !            79: }