mirror of https://github.com/macssh/macssh.git
86 lines
2.8 KiB
C
Executable File
86 lines
2.8 KiB
C
Executable File
/* mpq_sub -- subtract two rational numbers.
|
|
|
|
Copyright (C) 1991, 1994, 1995, 1996, 1997 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 2.1 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; see the file COPYING.LIB. If not, write to
|
|
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
|
|
MA 02111-1307, USA. */
|
|
|
|
#include "gmp.h"
|
|
#include "gmp-impl.h"
|
|
|
|
void
|
|
#if __STDC__
|
|
mpq_sub (mpq_ptr rop, mpq_srcptr op1, mpq_srcptr op2)
|
|
#else
|
|
mpq_sub (rop, op1, op2)
|
|
mpq_ptr rop;
|
|
mpq_srcptr op1;
|
|
mpq_srcptr op2;
|
|
#endif
|
|
{
|
|
mpz_t gcd;
|
|
mpz_t tmp1, tmp2;
|
|
mp_size_t op1_num_size = ABS (op1->_mp_num._mp_size);
|
|
mp_size_t op1_den_size = ABS (op1->_mp_den._mp_size);
|
|
mp_size_t op2_num_size = ABS (op2->_mp_num._mp_size);
|
|
mp_size_t op2_den_size = ABS (op2->_mp_den._mp_size);
|
|
TMP_DECL (marker);
|
|
|
|
TMP_MARK (marker);
|
|
MPZ_TMP_INIT (gcd, MIN (op1_den_size, op2_den_size));
|
|
MPZ_TMP_INIT (tmp1, op1_num_size + op2_den_size);
|
|
MPZ_TMP_INIT (tmp2, op2_num_size + op1_den_size);
|
|
|
|
/* ROP might be identical to either operand, so don't store the
|
|
result there until we are finished with the input operands. We
|
|
dare to overwrite the numerator of ROP when we are finished
|
|
with the numerators of OP1 and OP2. */
|
|
|
|
mpz_gcd (gcd, &(op1->_mp_den), &(op2->_mp_den));
|
|
if (gcd->_mp_size > 1 || gcd->_mp_d[0] != 1)
|
|
{
|
|
mpz_t t;
|
|
|
|
mpz_divexact (tmp1, &(op2->_mp_den), gcd);
|
|
mpz_mul (tmp1, &(op1->_mp_num), tmp1);
|
|
|
|
mpz_divexact (tmp2, &(op1->_mp_den), gcd);
|
|
mpz_mul (tmp2, &(op2->_mp_num), tmp2);
|
|
|
|
MPZ_TMP_INIT (t, MAX (ABS (tmp1->_mp_size), ABS (tmp2->_mp_size)) + 1);
|
|
|
|
mpz_sub (t, tmp1, tmp2);
|
|
mpz_divexact (tmp2, &(op1->_mp_den), gcd);
|
|
mpz_gcd (gcd, t, gcd);
|
|
|
|
mpz_divexact (&(rop->_mp_num), t, gcd);
|
|
|
|
mpz_divexact (tmp1, &(op2->_mp_den), gcd);
|
|
mpz_mul (&(rop->_mp_den), tmp1, tmp2);
|
|
}
|
|
else
|
|
{
|
|
/* The common divisor is 1. This is the case (for random input) with
|
|
probability 6/(pi**2). */
|
|
mpz_mul (tmp1, &(op1->_mp_num), &(op2->_mp_den));
|
|
mpz_mul (tmp2, &(op2->_mp_num), &(op1->_mp_den));
|
|
mpz_sub (&(rop->_mp_num), tmp1, tmp2);
|
|
mpz_mul (&(rop->_mp_den), &(op1->_mp_den), &(op2->_mp_den));
|
|
}
|
|
TMP_FREE (marker);
|
|
}
|