1 /* Compute complex base 10 logarithm for complex __float128.
2 Copyright (C) 1997-2012 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
20 #include "quadmath-imp.h"
24 #define M_LOG10_2q 0.3010299956639811952137388947244930267682Q
28 clog10q (__complex128 x)
31 int rcls = fpclassifyq (__real__ x);
32 int icls = fpclassifyq (__imag__ x);
34 if (__builtin_expect (rcls == QUADFP_ZERO && icls == QUADFP_ZERO, 0))
36 /* Real and imaginary part are 0.0. */
37 __imag__ result = signbitq (__real__ x) ? M_PIq : 0.0Q;
38 __imag__ result = copysignq (__imag__ result, __imag__ x);
39 /* Yes, the following line raises an exception. */
40 __real__ result = -1.0Q / fabsq (__real__ x);
42 else if (__builtin_expect (rcls != QUADFP_NAN && icls != QUADFP_NAN, 1))
44 /* Neither real nor imaginary part is NaN. */
45 __float128 absx = fabsq (__real__ x), absy = fabsq (__imag__ x);
55 if (absx > FLT128_MAX / 2.0Q)
58 absx = scalbnq (absx, scale);
59 absy = (absy >= FLT128_MIN * 2.0Q ? scalbnq (absy, scale) : 0.0Q);
61 else if (absx < FLT128_MIN && absy < FLT128_MIN)
63 scale = FLT128_MANT_DIG;
64 absx = scalbnq (absx, scale);
65 absy = scalbnq (absy, scale);
68 if (absx == 1.0Q && scale == 0)
70 __float128 absy2 = absy * absy;
71 if (absy2 <= FLT128_MIN * 2.0Q * M_LN10q)
73 = (absy2 / 2.0Q - absy2 * absy2 / 4.0Q) * M_LOG10Eq;
75 __real__ result = log1pq (absy2) * (M_LOG10Eq / 2.0Q);
77 else if (absx > 1.0Q && absx < 2.0Q && absy < 1.0Q && scale == 0)
79 __float128 d2m1 = (absx - 1.0Q) * (absx + 1.0Q);
80 if (absy >= FLT128_EPSILON)
82 __real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
86 && absy < FLT128_EPSILON / 2.0Q
89 __float128 d2m1 = (absx - 1.0Q) * (absx + 1.0Q);
90 __real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
92 else if (absx < 1.0Q && (absx >= 0.75Q || absy >= 0.5Q) && scale == 0)
94 __float128 d2m1 = __quadmath_x2y2m1q (absx, absy);
95 __real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
99 __float128 d = hypotq (absx, absy);
100 __real__ result = log10q (d) - scale * M_LOG10_2q;
103 __imag__ result = M_LOG10Eq * atan2q (__imag__ x, __real__ x);
107 __imag__ result = nanq ("");
108 if (rcls == QUADFP_INFINITE || icls == QUADFP_INFINITE)
109 /* Real or imaginary part is infinite. */
110 __real__ result = HUGE_VALQ;
112 __real__ result = nanq ("");