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Annotation of OpenXM_contrib/gmp/mpq/div.c, Revision 1.1.1.1

1.1       maekawa     1: /* mpq_div -- divide 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_div (mpq_ptr quot, mpq_srcptr op1, mpq_srcptr op2)
                     28: #else
                     29: mpq_div (quot, op1, op2)
                     30:      mpq_ptr quot;
                     31:      mpq_srcptr op1;
                     32:      mpq_srcptr op2;
                     33: #endif
                     34: {
                     35:   mpz_t gcd1, gcd2;
                     36:   mpz_t tmp1, tmp2;
                     37:   mpz_t numtmp;
                     38:
                     39:   mpz_init (gcd1);
                     40:   mpz_init (gcd2);
                     41:   mpz_init (tmp1);
                     42:   mpz_init (tmp2);
                     43:   mpz_init (numtmp);
                     44:
                     45:   /* QUOT 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 QUOT when we are finished
                     48:      with the numerators of OP1 and OP2.  */
                     49:
                     50:   mpz_gcd (gcd1, &(op1->_mp_num), &(op2->_mp_num));
                     51:   mpz_gcd (gcd2, &(op2->_mp_den), &(op1->_mp_den));
                     52:
                     53:   if (gcd1->_mp_size > 1 || gcd1->_mp_d[0] != 1)
                     54:     mpz_divexact (tmp1, &(op1->_mp_num), gcd1);
                     55:   else
                     56:     mpz_set (tmp1, &(op1->_mp_num));
                     57:
                     58:   if (gcd2->_mp_size > 1 || gcd2->_mp_d[0] != 1)
                     59:     mpz_divexact (tmp2, &(op2->_mp_den), gcd2);
                     60:   else
                     61:     mpz_set (tmp2, &(op2->_mp_den));
                     62:
                     63:   mpz_mul (numtmp, tmp1, tmp2);
                     64:
                     65:   if (gcd1->_mp_size > 1 || gcd1->_mp_d[0] != 1)
                     66:     mpz_divexact (tmp1, &(op2->_mp_num), gcd1);
                     67:   else
                     68:     mpz_set (tmp1, &(op2->_mp_num));
                     69:
                     70:   if (gcd2->_mp_size > 1 || gcd2->_mp_d[0] != 1)
                     71:     mpz_divexact (tmp2, &(op1->_mp_den), gcd2);
                     72:   else
                     73:     mpz_set (tmp2, &(op1->_mp_den));
                     74:
                     75:   mpz_mul (&(quot->_mp_den), tmp1, tmp2);
                     76:
                     77:   /* We needed to go via NUMTMP to take care of QUOT being the same
                     78:      as either input operands.  Now move NUMTMP to QUOT->_mp_num.  */
                     79:   mpz_set (&(quot->_mp_num), numtmp);
                     80:
                     81:   /* Keep the denominator positive.  */
                     82:   if (quot->_mp_den._mp_size < 0)
                     83:     {
                     84:       quot->_mp_den._mp_size = -quot->_mp_den._mp_size;
                     85:       quot->_mp_num._mp_size = -quot->_mp_num._mp_size;
                     86:     }
                     87:
                     88:   mpz_clear (numtmp);
                     89:   mpz_clear (tmp2);
                     90:   mpz_clear (tmp1);
                     91:   mpz_clear (gcd2);
                     92:   mpz_clear (gcd1);
                     93: }