1 /* Return arc hyperbole sine for long double value, with the imaginary
2 part of the result possibly adjusted for use in computing other
4 Copyright (C) 1997-2013 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
12 The GNU C 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 GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <http://www.gnu.org/licenses/>. */
23 #include <math_private.h>
26 /* To avoid spurious overflows, use this definition to treat IBM long
27 double as approximating an IEEE-style format. */
28 #if LDBL_MANT_DIG == 106
30 # define LDBL_EPSILON 0x1p-106L
33 /* Return the complex inverse hyperbolic sine of finite nonzero Z,
34 with the imaginary part of the result subtracted from pi/2 if ADJ
37 __complex__ long double
38 __kernel_casinhl (__complex__ long double x, int adj)
40 __complex__ long double res;
42 __complex__ long double y;
44 /* Avoid cancellation by reducing to the first quadrant. */
45 rx = fabsl (__real__ x);
46 ix = fabsl (__imag__ x);
48 if (rx >= 1.0L / LDBL_EPSILON || ix >= 1.0L / LDBL_EPSILON)
50 /* For large x in the first quadrant, x + csqrt (1 + x * x)
51 is sufficiently close to 2 * x to make no significant
52 difference to the result; avoid possible overflow from
53 the squaring and addition. */
59 long double t = __real__ y;
60 __real__ y = __copysignl (__imag__ y, __imag__ x);
65 __real__ res += M_LN2l;
69 __real__ y = (rx - ix) * (rx + ix) + 1.0;
70 __imag__ y = 2.0 * rx * ix;
79 long double t = __real__ y;
80 __real__ y = __copysignl (__imag__ y, __imag__ x);
87 /* Give results the correct sign for the original argument. */
88 __real__ res = __copysignl (__real__ res, __real__ x);
89 __imag__ res = __copysignl (__imag__ res, (adj ? 1.0L : __imag__ x));