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https://github.com/jart/cosmopolitan.git
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2fc507c98f
* modelines: tw -> sw shiftwidth, not textwidth. * space-surround modelines * fix irregular modelines * Fix modeline in titlegen.c
82 lines
3.7 KiB
C
82 lines
3.7 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│ vi: set noet ft=c ts=8 sw=8 fenc=utf-8 :vi │
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╚──────────────────────────────────────────────────────────────────────────────╝
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│ │
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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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│ │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/math.h"
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#include "libc/tinymath/feval.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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/**
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* Returns hyperbolic tangent of 𝑥.
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*/
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double tanh(double x)
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{
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union {double f; uint64_t i;} u = {.f = x};
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uint32_t w;
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int sign;
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double_t t;
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/* x = |x| */
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sign = u.i >> 63;
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u.i &= (uint64_t)-1/2;
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x = u.f;
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w = u.i >> 32;
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if (w > 0x3fe193ea) {
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/* |x| > log(3)/2 ~= 0.5493 or nan */
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if (w > 0x40340000) {
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/* |x| > 20 or nan */
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/* note: this branch avoids raising overflow */
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t = 1 - 0/x;
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} else {
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t = expm1(2*x);
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t = 1 - 2/(t+2);
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}
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} else if (w > 0x3fd058ae) {
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/* |x| > log(5/3)/2 ~= 0.2554 */
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t = expm1(2*x);
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t = t/(t+2);
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} else if (w >= 0x00100000) {
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/* |x| >= 0x1p-1022, up to 2ulp error in [0.1,0.2554] */
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t = expm1(-2*x);
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t = -t/(t+2);
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} else {
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/* |x| is subnormal */
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/* note: the branch above would not raise underflow in [0x1p-1023,0x1p-1022) */
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fevalf(x);
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t = x;
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}
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return sign ? -t : t;
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}
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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__weak_reference(tanh, tanhl);
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#endif
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