1 /* mpfr_reldiff -- compute relative difference of two floating-point numbers.
3 Copyright 2000-2001, 2004-2016 Free Software Foundation, Inc.
4 Contributed by the AriC and Caramba projects, INRIA.
6 This file is part of the GNU MPFR Library.
8 The GNU MPFR Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or (at your
11 option) any later version.
13 The GNU MPFR Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16 License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23 #include "mpfr-impl.h"
25 /* reldiff(b, c) = abs(b-c)/b */
27 mpfr_reldiff (mpfr_ptr a
, mpfr_srcptr b
, mpfr_srcptr c
, mpfr_rnd_t rnd_mode
)
31 if (MPFR_ARE_SINGULAR (b
, c
))
33 if (MPFR_IS_NAN(b
) || MPFR_IS_NAN(c
))
38 else if (MPFR_IS_INF(b
))
40 if (MPFR_IS_INF (c
) && (MPFR_SIGN (c
) == MPFR_SIGN (b
)))
46 else if (MPFR_IS_INF(c
))
48 MPFR_SET_SAME_SIGN (a
, b
);
52 else if (MPFR_IS_ZERO(b
)) /* reldiff = abs(c)/c = sign(c) */
54 mpfr_set_si (a
, MPFR_INT_SIGN (c
), rnd_mode
);
62 mpfr_init2 (b_copy
, MPFR_PREC(b
));
63 mpfr_set (b_copy
, b
, MPFR_RNDN
);
66 mpfr_sub (a
, b
, c
, rnd_mode
);
67 mpfr_abs (a
, a
, rnd_mode
); /* for compatibility with MPF */
68 mpfr_div (a
, a
, (a
== b
) ? b_copy
: b
, rnd_mode
);