mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 13:00:06 +00:00
55 lines
2.0 KiB
C
55 lines
2.0 KiB
C
/* Single-precision vector (SVE) atanh function
|
|
|
|
Copyright (C) 2024 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include "sv_log1pf_inline.h"
|
|
|
|
#define One (0x3f800000)
|
|
#define Half (0x3f000000)
|
|
|
|
static svfloat32_t NOINLINE
|
|
special_case (svfloat32_t x, svfloat32_t y, svbool_t special)
|
|
{
|
|
return sv_call_f32 (atanhf, x, y, special);
|
|
}
|
|
|
|
/* Approximation for vector single-precision atanh(x) using modified log1p.
|
|
The maximum error is 2.28 ULP:
|
|
_ZGVsMxv_atanhf(0x1.ff1194p-5) got 0x1.ffbbbcp-5
|
|
want 0x1.ffbbb6p-5. */
|
|
svfloat32_t SV_NAME_F1 (atanh) (svfloat32_t x, const svbool_t pg)
|
|
{
|
|
svfloat32_t ax = svabs_x (pg, x);
|
|
svuint32_t iax = svreinterpret_u32 (ax);
|
|
svuint32_t sign = sveor_x (pg, svreinterpret_u32 (x), iax);
|
|
svfloat32_t halfsign = svreinterpret_f32 (svorr_x (pg, sign, Half));
|
|
svbool_t special = svcmpge (pg, iax, One);
|
|
|
|
/* Computation is performed based on the following sequence of equality:
|
|
* (1+x)/(1-x) = 1 + 2x/(1-x). */
|
|
svfloat32_t y = svadd_x (pg, ax, ax);
|
|
y = svdiv_x (pg, y, svsub_x (pg, sv_f32 (1), ax));
|
|
/* ln((1+x)/(1-x)) = ln(1+2x/(1-x)) = ln(1 + y). */
|
|
y = sv_log1pf_inline (y, pg);
|
|
|
|
if (__glibc_unlikely (svptest_any (pg, special)))
|
|
return special_case (x, svmul_x (pg, halfsign, y), special);
|
|
|
|
return svmul_x (pg, halfsign, y);
|
|
}
|