Add version set GLIBC_2.19 for linux/powerpc
[glibc.git] / math / s_csqrtf.c
blob7f45cc1320b4db9799dd934328cfdae0982146f7
1 /* Complex square root of float value.
2 Copyright (C) 1997-2015 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Based on an algorithm by Stephen L. Moshier <moshier@world.std.com>.
5 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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/>. */
21 #include <complex.h>
22 #include <math.h>
23 #include <math_private.h>
24 #include <float.h>
26 __complex__ float
27 __csqrtf (__complex__ float x)
29 __complex__ float res;
30 int rcls = fpclassify (__real__ x);
31 int icls = fpclassify (__imag__ x);
33 if (__glibc_unlikely (rcls <= FP_INFINITE || icls <= FP_INFINITE))
35 if (icls == FP_INFINITE)
37 __real__ res = HUGE_VALF;
38 __imag__ res = __imag__ x;
40 else if (rcls == FP_INFINITE)
42 if (__real__ x < 0.0)
44 __real__ res = icls == FP_NAN ? __nanf ("") : 0;
45 __imag__ res = __copysignf (HUGE_VALF, __imag__ x);
47 else
49 __real__ res = __real__ x;
50 __imag__ res = (icls == FP_NAN
51 ? __nanf ("") : __copysignf (0.0, __imag__ x));
54 else
56 __real__ res = __nanf ("");
57 __imag__ res = __nanf ("");
60 else
62 if (__glibc_unlikely (icls == FP_ZERO))
64 if (__real__ x < 0.0)
66 __real__ res = 0.0;
67 __imag__ res = __copysignf (__ieee754_sqrtf (-__real__ x),
68 __imag__ x);
70 else
72 __real__ res = fabsf (__ieee754_sqrtf (__real__ x));
73 __imag__ res = __copysignf (0.0, __imag__ x);
76 else if (__glibc_unlikely (rcls == FP_ZERO))
78 float r;
79 if (fabsf (__imag__ x) >= 2.0f * FLT_MIN)
80 r = __ieee754_sqrtf (0.5f * fabsf (__imag__ x));
81 else
82 r = 0.5f * __ieee754_sqrtf (2.0f * fabsf (__imag__ x));
84 __real__ res = r;
85 __imag__ res = __copysignf (r, __imag__ x);
87 else
89 float d, r, s;
90 int scale = 0;
92 if (fabsf (__real__ x) > FLT_MAX / 4.0f)
94 scale = 1;
95 __real__ x = __scalbnf (__real__ x, -2 * scale);
96 __imag__ x = __scalbnf (__imag__ x, -2 * scale);
98 else if (fabsf (__imag__ x) > FLT_MAX / 4.0f)
100 scale = 1;
101 if (fabsf (__real__ x) >= 4.0f * FLT_MIN)
102 __real__ x = __scalbnf (__real__ x, -2 * scale);
103 else
104 __real__ x = 0.0f;
105 __imag__ x = __scalbnf (__imag__ x, -2 * scale);
107 else if (fabsf (__real__ x) < FLT_MIN
108 && fabsf (__imag__ x) < FLT_MIN)
110 scale = -(FLT_MANT_DIG / 2);
111 __real__ x = __scalbnf (__real__ x, -2 * scale);
112 __imag__ x = __scalbnf (__imag__ x, -2 * scale);
115 d = __ieee754_hypotf (__real__ x, __imag__ x);
116 /* Use the identity 2 Re res Im res = Im x
117 to avoid cancellation error in d +/- Re x. */
118 if (__real__ x > 0)
120 r = __ieee754_sqrtf (0.5f * (d + __real__ x));
121 if (scale == 1 && fabsf (__imag__ x) < 1.0f)
123 /* Avoid possible intermediate underflow. */
124 s = __imag__ x / r;
125 r = __scalbnf (r, scale);
126 scale = 0;
128 else
129 s = 0.5f * (__imag__ x / r);
131 else
133 s = __ieee754_sqrtf (0.5f * (d - __real__ x));
134 if (scale == 1 && fabsf (__imag__ x) < 1.0f)
136 /* Avoid possible intermediate underflow. */
137 r = fabsf (__imag__ x / s);
138 s = __scalbnf (s, scale);
139 scale = 0;
141 else
142 r = fabsf (0.5f * (__imag__ x / s));
145 if (scale)
147 r = __scalbnf (r, scale);
148 s = __scalbnf (s, scale);
151 __real__ res = r;
152 __imag__ res = __copysignf (s, __imag__ x);
156 return res;
158 #ifndef __csqrtf
159 weak_alias (__csqrtf, csqrtf)
160 #endif