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Annotation of OpenXM_contrib/gmp/mpq/mul.c, Revision 1.1.1.2

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
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:
                     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: }