1 /* mpq_add -- add two rational numbers.
3 Copyright (C) 1991 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 The GNU MP Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with the GNU MP Library; see the file COPYING. If not, write to
19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
26 mpq_add (MP_RAT *sum, const MP_RAT *a1, const MP_RAT *a2)
42 /* SUM might be identical to either operand, so don't store the
43 result there until we are finished with the input operands. We
44 dare to overwrite the numerator of SUM when we are finished
45 with the numerators of A1 and A2. */
47 mpz_gcd (&gcd1, &(a1->den), &(a2->den));
48 if (gcd1.size > 1 || gcd1.d[0] != 1)
54 mpz_div (&tmp1, &(a2->den), &gcd1);
55 mpz_mul (&tmp1, &(a1->num), &tmp1);
57 mpz_div (&tmp2, &(a1->den), &gcd1);
58 mpz_mul (&tmp2, &(a2->num), &tmp2);
60 mpz_add (&t, &tmp1, &tmp2);
61 mpz_gcd (&gcd2, &t, &gcd1);
63 mpz_div (&(sum->num), &t, &gcd2);
65 mpz_div (&tmp1, &(a1->den), &gcd1);
66 mpz_div (&tmp2, &(a2->den), &gcd2);
67 mpz_mul (&(sum->den), &tmp1, &tmp2);
73 /* The common divisior is 1. This is the case (for random input) with
74 probability 6/(pi**2). */
75 mpz_mul (&tmp1, &(a1->num), &(a2->den));
76 mpz_mul (&tmp2, &(a2->num), &(a1->den));
77 mpz_add (&(sum->num), &tmp1, &tmp2);
78 mpz_mul (&(sum->den), &(a1->den), &(a2->den));