source: asp3_tinet_ecnl_arm/trunk/musl-1.1.18/src/math/tanhf.c@ 352

Last change on this file since 352 was 352, checked in by coas-nagasima, 6 years ago

arm向けASP3版ECNLを追加
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File size: 653 bytes
Line 
1#include "libm.h"
2
3float tanhf(float x)
4{
5 union {float f; uint32_t i;} u = {.f = x};
6 uint32_t w;
7 int sign;
8 float t;
9
10 /* x = |x| */
11 sign = u.i >> 31;
12 u.i &= 0x7fffffff;
13 x = u.f;
14 w = u.i;
15
16 if (w > 0x3f0c9f54) {
17 /* |x| > log(3)/2 ~= 0.5493 or nan */
18 if (w > 0x41200000) {
19 /* |x| > 10 */
20 t = 1 + 0/x;
21 } else {
22 t = expm1f(2*x);
23 t = 1 - 2/(t+2);
24 }
25 } else if (w > 0x3e82c578) {
26 /* |x| > log(5/3)/2 ~= 0.2554 */
27 t = expm1f(2*x);
28 t = t/(t+2);
29 } else if (w >= 0x00800000) {
30 /* |x| >= 0x1p-126 */
31 t = expm1f(-2*x);
32 t = -t/(t+2);
33 } else {
34 /* |x| is subnormal */
35 FORCE_EVAL(x*x);
36 t = x;
37 }
38 return sign ? -t : t;
39}
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