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Annotation of OpenXM_contrib/gmp/mpq/mul.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpq_mul -- mutiply two rational numbers.
                      2:
1.1.1.3 ! ohara       3: Copyright 1991, 1994, 1995, 1996, 2000, 2001 Free Software Foundation, Inc.
1.1       maekawa     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
1.1.1.2   maekawa     8: it under the terms of the GNU Lesser General Public License as published by
                      9: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1       maekawa    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
1.1.1.2   maekawa    14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    15: License for more details.
                     16:
1.1.1.2   maekawa    17: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    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:
1.1.1.3 ! ohara      25:
1.1       maekawa    26: void
                     27: mpq_mul (mpq_ptr prod, mpq_srcptr op1, mpq_srcptr op2)
                     28: {
                     29:   mpz_t gcd1, gcd2;
                     30:   mpz_t tmp1, tmp2;
                     31:
1.1.1.3 ! ohara      32:   if (op1 == op2)
        !            33:     {
        !            34:       /* No need for any GCDs when squaring. */
        !            35:       mpz_mul (mpq_numref (prod), mpq_numref (op1), mpq_numref (op1));
        !            36:       mpz_mul (mpq_denref (prod), mpq_denref (op1), mpq_denref (op1));
        !            37:       return;
        !            38:     }
        !            39:
1.1       maekawa    40:   mpz_init (gcd1);
                     41:   mpz_init (gcd2);
                     42:   mpz_init (tmp1);
                     43:   mpz_init (tmp2);
                     44:
                     45:   /* PROD might be identical to either operand, so don't store the
                     46:      result there until we are finished with the input operands.  We
                     47:      dare to overwrite the numerator of PROD when we are finished
                     48:      with the numerators of OP1 and OP2.  */
                     49:
                     50:   mpz_gcd (gcd1, &(op1->_mp_num), &(op2->_mp_den));
                     51:   mpz_gcd (gcd2, &(op2->_mp_num), &(op1->_mp_den));
                     52:
1.1.1.3 ! ohara      53:   mpz_divexact_gcd (tmp1, &(op1->_mp_num), gcd1);
        !            54:   mpz_divexact_gcd (tmp2, &(op2->_mp_num), gcd2);
1.1       maekawa    55:
                     56:   mpz_mul (&(prod->_mp_num), tmp1, tmp2);
                     57:
1.1.1.3 ! ohara      58:   mpz_divexact_gcd (tmp1, &(op2->_mp_den), gcd1);
        !            59:   mpz_divexact_gcd (tmp2, &(op1->_mp_den), gcd2);
1.1       maekawa    60:
                     61:   mpz_mul (&(prod->_mp_den), tmp1, tmp2);
                     62:
                     63:   mpz_clear (tmp2);
                     64:   mpz_clear (tmp1);
                     65:   mpz_clear (gcd2);
                     66:   mpz_clear (gcd1);
                     67: }