2021-08-16 22:26:31 +00:00
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/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
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╚──────────────────────────────────────────────────────────────────────────────╝
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2021-02-28 09:06:00 +00:00
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│ │
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2021-08-16 22:26:31 +00:00
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│ Musl Libc │
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│ Copyright © 2005-2014 Rich Felker, et al. │
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│ │
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│ Permission is hereby granted, free of charge, to any person obtaining │
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│ a copy of this software and associated documentation files (the │
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│ "Software"), to deal in the Software without restriction, including │
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│ without limitation the rights to use, copy, modify, merge, publish, │
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│ distribute, sublicense, and/or sell copies of the Software, and to │
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│ permit persons to whom the Software is furnished to do so, subject to │
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│ the following conditions: │
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│ │
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│ The above copyright notice and this permission notice shall be │
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│ included in all copies or substantial portions of the Software. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
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│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
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│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
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│ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY │
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│ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, │
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│ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE │
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│ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
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2021-02-28 09:06:00 +00:00
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│ │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/math.h"
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2021-08-16 22:26:31 +00:00
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#include "libc/tinymath/ldshape.internal.h"
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asm(".ident\t\"\\n\\n\
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Musl libc (MIT License)\\n\
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Copyright 2005-2014 Rich Felker, et. al.\"");
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asm(".include \"libc/disclaimer.inc\"");
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/* clang-format off */
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2021-02-28 09:06:00 +00:00
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/**
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* Returns hyperbolic tangent of 𝑥.
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2021-08-16 22:26:31 +00:00
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*
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* tanh(x) = (exp(x) - exp(-x))/(exp(x) + exp(-x))
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* = (exp(2*x) - 1)/(exp(2*x) - 1 + 2)
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* = (1 - exp(-2*x))/(exp(-2*x) - 1 + 2)
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2021-02-28 09:06:00 +00:00
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*/
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2021-08-16 22:26:31 +00:00
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long double tanhl(long double x)
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{
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union ldshape u = {x};
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unsigned ex = u.i.se & 0x7fff;
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unsigned sign = u.i.se & 0x8000;
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uint32_t w;
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long double t;
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/* x = |x| */
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u.i.se = ex;
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x = u.f;
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w = u.i.m >> 32;
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if (ex > 0x3ffe || (ex == 0x3ffe && w > 0x8c9f53d5)) {
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/* |x| > log(3)/2 ~= 0.5493 or nan */
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if (ex >= 0x3fff+5) {
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/* |x| >= 32 */
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t = 1 + 0/(x + 0x1p-120f);
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} else {
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t = expm1l(2*x);
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t = 1 - 2/(t+2);
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}
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} else if (ex > 0x3ffd || (ex == 0x3ffd && w > 0x82c577d4)) {
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/* |x| > log(5/3)/2 ~= 0.2554 */
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t = expm1l(2*x);
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t = t/(t+2);
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} else {
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/* |x| is small */
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t = expm1l(-2*x);
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t = -t/(t+2);
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}
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return sign ? -t : t;
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2021-02-28 09:06:00 +00:00
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}
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