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114 lines
3.7 KiB
114 lines
3.7 KiB
4 months ago
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/*
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* Copyright (c) 2014,2015 Advanced Micro Devices, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* 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, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <clc/clc.h>
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#include "math.h"
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#include "../clcmacro.h"
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_CLC_OVERLOAD _CLC_DEF float atanh(float x) {
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uint ux = as_uint(x);
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uint ax = ux & EXSIGNBIT_SP32;
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uint xs = ux ^ ax;
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// |x| > 1 or NaN
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float z = as_float(QNANBITPATT_SP32);
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// |x| == 1
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float t = as_float(xs | PINFBITPATT_SP32);
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z = ax == 0x3f800000U ? t : z;
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// 1/2 <= |x| < 1
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t = as_float(ax);
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t = MATH_DIVIDE(2.0f*t, 1.0f - t);
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t = 0.5f * log1p(t);
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t = as_float(xs | as_uint(t));
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z = ax < 0x3f800000U ? t : z;
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// |x| < 1/2
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t = x * x;
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float a = mad(mad(0.92834212715e-2f, t, -0.28120347286e0f), t, 0.39453629046e0f);
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float b = mad(mad(0.45281890445e0f, t, -0.15537744551e1f), t, 0.11836088638e1f);
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float p = MATH_DIVIDE(a, b);
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t = mad(x*t, p, x);
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z = ax < 0x3f000000 ? t : z;
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// |x| < 2^-13
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z = ax < 0x39000000U ? x : z;
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return z;
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}
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_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, float, atanh, float)
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#ifdef cl_khr_fp64
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#pragma OPENCL EXTENSION cl_khr_fp64 : enable
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_CLC_OVERLOAD _CLC_DEF double atanh(double x) {
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double absx = fabs(x);
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double ret = absx == 1.0 ? as_double(PINFBITPATT_DP64) : as_double(QNANBITPATT_DP64);
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// |x| >= 0.5
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// Note that atanh(x) = 0.5 * ln((1+x)/(1-x))
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// For greater accuracy we use
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// ln((1+x)/(1-x)) = ln(1 + 2x/(1-x)) = log1p(2x/(1-x)).
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double r = 0.5 * log1p(2.0 * absx / (1.0 - absx));
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ret = absx < 1.0 ? r : ret;
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r = -ret;
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ret = x < 0.0 ? r : ret;
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// Arguments up to 0.5 in magnitude are
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// approximated by a [5,5] minimax polynomial
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double t = x * x;
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double pn = fma(t,
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fma(t,
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fma(t,
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fma(t,
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fma(t, -0.10468158892753136958e-3, 0.28728638600548514553e-1),
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-0.28180210961780814148e0),
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0.88468142536501647470e0),
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-0.11028356797846341457e1),
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0.47482573589747356373e0);
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double pd = fma(t,
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fma(t,
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fma(t,
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fma(t,
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fma(t, -0.35861554370169537512e-1, 0.49561196555503101989e0),
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-0.22608883748988489342e1),
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0.45414700626084508355e1),
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-0.41631933639693546274e1),
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0.14244772076924206909e1);
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r = fma(x*t, pn/pd, x);
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ret = absx < 0.5 ? r : ret;
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return ret;
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}
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_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, atanh, double)
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#endif
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