hppa: Cleanup libm-test-ulps.
[glibc.git] / math / s_ctanl.c
bloba22e30adeec35366360988ff36ad99cc361bb95d
1 /* Complex tangent function for long double.
2 Copyright (C) 1997-2013 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 <complex.h>
21 #include <fenv.h>
22 #include <math.h>
23 #include <math_private.h>
24 #include <float.h>
26 __complex__ long double
27 __ctanl (__complex__ long double x)
29 __complex__ long double res;
31 if (__builtin_expect (!isfinite (__real__ x) || !isfinite (__imag__ x), 0))
33 if (__isinf_nsl (__imag__ x))
35 __real__ res = __copysignl (0.0, __real__ x);
36 __imag__ res = __copysignl (1.0, __imag__ x);
38 else if (__real__ x == 0.0)
40 res = x;
42 else
44 __real__ res = __nanl ("");
45 __imag__ res = __nanl ("");
47 if (__isinf_nsl (__real__ x))
48 feraiseexcept (FE_INVALID);
51 else
53 long double sinrx, cosrx;
54 long double den;
55 const int t = (int) ((LDBL_MAX_EXP - 1) * M_LN2l / 2);
56 int rcls = fpclassify (__real__ x);
58 /* tan(x+iy) = (sin(2x) + i*sinh(2y))/(cos(2x) + cosh(2y))
59 = (sin(x)*cos(x) + i*sinh(y)*cosh(y)/(cos(x)^2 + sinh(y)^2). */
61 if (__builtin_expect (rcls != FP_SUBNORMAL, 1))
63 __sincosl (__real__ x, &sinrx, &cosrx);
65 else
67 sinrx = __real__ x;
68 cosrx = 1.0;
71 if (fabsl (__imag__ x) > t)
73 /* Avoid intermediate overflow when the real part of the
74 result may be subnormal. Ignoring negligible terms, the
75 imaginary part is +/- 1, the real part is
76 sin(x)*cos(x)/sinh(y)^2 = 4*sin(x)*cos(x)/exp(2y). */
77 long double exp_2t = __ieee754_expl (2 * t);
79 __imag__ res = __copysignl (1.0, __imag__ x);
80 __real__ res = 4 * sinrx * cosrx;
81 __imag__ x = fabsl (__imag__ x);
82 __imag__ x -= t;
83 __real__ res /= exp_2t;
84 if (__imag__ x > t)
86 /* Underflow (original imaginary part of x has absolute
87 value > 2t). */
88 __real__ res /= exp_2t;
90 else
91 __real__ res /= __ieee754_expl (2 * __imag__ x);
93 else
95 long double sinhix, coshix;
96 if (fabsl (__imag__ x) > LDBL_MIN)
98 sinhix = __ieee754_sinhl (__imag__ x);
99 coshix = __ieee754_coshl (__imag__ x);
101 else
103 sinhix = __imag__ x;
104 coshix = 1.0L;
107 if (fabsl (sinhix) > fabsl (cosrx) * LDBL_EPSILON)
108 den = cosrx * cosrx + sinhix * sinhix;
109 else
110 den = cosrx * cosrx;
111 __real__ res = sinrx * cosrx / den;
112 __imag__ res = sinhix * coshix / den;
116 return res;
118 weak_alias (__ctanl, ctanl)