359 lines
12 KiB
C
359 lines
12 KiB
C
/* @(#)e_lgamma_r.c 1.3 95/01/18 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*
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* See e_lgamma_r.c for complete comments.
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*
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* Converted to long double by Steven G. Kargl.
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*/
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#ifdef __i386__
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#include <ieeefp.h>
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#endif
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#include "fpmath.h"
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#include "math.h"
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#include "math_private.h"
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static const volatile double vzero = 0;
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static const double
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zero= 0,
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half= 0.5,
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one = 1;
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static const union IEEEl2bits
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piu = LD80C(0xc90fdaa22168c235, 1, 3.14159265358979323851e+00L);
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#define pi (piu.e)
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/*
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* Domain y in [0x1p-70, 0.27], range ~[-4.5264e-22, 4.5264e-22]:
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* |(lgamma(2 - y) + y / 2) / y - a(y)| < 2**-70.9
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*/
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static const union IEEEl2bits
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a0u = LD80C(0x9e233f1bed863d26, -4, 7.72156649015328606028e-02L),
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a1u = LD80C(0xa51a6625307d3249, -2, 3.22467033424113218889e-01L),
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a2u = LD80C(0x89f000d2abafda8c, -4, 6.73523010531979398946e-02L),
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a3u = LD80C(0xa8991563eca75f26, -6, 2.05808084277991211934e-02L),
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a4u = LD80C(0xf2027e10634ce6b6, -8, 7.38555102796070454026e-03L),
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a5u = LD80C(0xbd6eb76dd22187f4, -9, 2.89051035162703932972e-03L),
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a6u = LD80C(0x9c562ab05e0458ed, -10, 1.19275351624639999297e-03L),
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a7u = LD80C(0x859baed93ee48e46, -11, 5.09674593842117925320e-04L),
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a8u = LD80C(0xe9f28a4432949af2, -13, 2.23109648015769155122e-04L),
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a9u = LD80C(0xd12ad0d9b93c6bb0, -14, 9.97387167479808509830e-05L),
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a10u= LD80C(0xb7522643c78a219b, -15, 4.37071076331030136818e-05L),
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a11u= LD80C(0xca024dcdece2cb79, -16, 2.40813493372040143061e-05L),
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a12u= LD80C(0xbb90fb6968ebdbf9, -19, 2.79495621083634031729e-06L),
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a13u= LD80C(0xba1c9ffeeae07b37, -17, 1.10931287015513924136e-05L);
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#define a0 (a0u.e)
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#define a1 (a1u.e)
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#define a2 (a2u.e)
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#define a3 (a3u.e)
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#define a4 (a4u.e)
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#define a5 (a5u.e)
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#define a6 (a6u.e)
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#define a7 (a7u.e)
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#define a8 (a8u.e)
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#define a9 (a9u.e)
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#define a10 (a10u.e)
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#define a11 (a11u.e)
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#define a12 (a12u.e)
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#define a13 (a13u.e)
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/*
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* Domain x in [tc-0.24, tc+0.28], range ~[-6.1205e-22, 6.1205e-22]:
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* |(lgamma(x) - tf) - t(x - tc)| < 2**-70.5
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*/
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static const union IEEEl2bits
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tcu = LD80C(0xbb16c31ab5f1fb71, 0, 1.46163214496836234128e+00L),
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tfu = LD80C(0xf8cdcde61c520e0f, -4, -1.21486290535849608093e-01L),
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ttu = LD80C(0xd46ee54b27d4de99, -69, -2.81152980996018785880e-21L),
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t0u = LD80C(0x80b9406556a62a6b, -68, 3.40728634996055147231e-21L),
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t1u = LD80C(0xc7e9c6f6df3f8c39, -67, -1.05833162742737073665e-20L),
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t2u = LD80C(0xf7b95e4771c55d51, -2, 4.83836122723810583532e-01L),
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t3u = LD80C(0x97213c6e35e119ff, -3, -1.47587722994530691476e-01L),
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t4u = LD80C(0x845a14a6a81dc94b, -4, 6.46249402389135358063e-02L),
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t5u = LD80C(0x864d46fa89997796, -5, -3.27885410884846056084e-02L),
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t6u = LD80C(0x93373cbd00297438, -6, 1.79706751150707171293e-02L),
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t7u = LD80C(0xa8fcfca7eddc8d1d, -7, -1.03142230361450732547e-02L),
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t8u = LD80C(0xc7e7015ff4bc45af, -8, 6.10053603296546099193e-03L),
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t9u = LD80C(0xf178d2247adc5093, -9, -3.68456964904901200152e-03L),
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t10u = LD80C(0x94188d58f12e5e9f, -9, 2.25976420273774583089e-03L),
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t11u = LD80C(0xb7cbaef14e1406f1, -10, -1.40224943666225639823e-03L),
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t12u = LD80C(0xe63a671e6704ea4d, -11, 8.78250640744776944887e-04L),
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t13u = LD80C(0x914b6c9cae61783e, -11, -5.54255012657716808811e-04L),
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t14u = LD80C(0xb858f5bdb79276fe, -12, 3.51614951536825927370e-04L),
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t15u = LD80C(0xea73e744c34b9591, -13, -2.23591563824520112236e-04L),
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t16u = LD80C(0x99aeabb0d67ba835, -13, 1.46562869351659194136e-04L),
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t17u = LD80C(0xd7c6938325db2024, -14, -1.02889866046435680588e-04L),
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t18u = LD80C(0xe24cb1e3b0474775, -15, 5.39540265505221957652e-05L);
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#define tc (tcu.e)
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#define tf (tfu.e)
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#define tt (ttu.e)
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#define t0 (t0u.e)
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#define t1 (t1u.e)
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#define t2 (t2u.e)
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#define t3 (t3u.e)
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#define t4 (t4u.e)
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#define t5 (t5u.e)
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#define t6 (t6u.e)
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#define t7 (t7u.e)
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#define t8 (t8u.e)
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#define t9 (t9u.e)
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#define t10 (t10u.e)
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#define t11 (t11u.e)
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#define t12 (t12u.e)
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#define t13 (t13u.e)
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#define t14 (t14u.e)
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#define t15 (t15u.e)
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#define t16 (t16u.e)
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#define t17 (t17u.e)
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#define t18 (t18u.e)
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/*
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* Domain y in [-0.1, 0.232], range ~[-8.1938e-22, 8.3815e-22]:
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* |(lgamma(1 + y) + 0.5 * y) / y - u(y) / v(y)| < 2**-71.2
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*/
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static const union IEEEl2bits
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u0u = LD80C(0x9e233f1bed863d27, -4, -7.72156649015328606095e-02L),
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u1u = LD80C(0x98280ee45e4ddd3d, -1, 5.94361239198682739769e-01L),
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u2u = LD80C(0xe330c8ead4130733, 0, 1.77492629495841234275e+00L),
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u3u = LD80C(0xd4a213f1a002ec52, 0, 1.66119622514818078064e+00L),
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u4u = LD80C(0xa5a9ca6f5bc62163, -1, 6.47122051417476492989e-01L),
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u5u = LD80C(0xc980e49cd5b019e6, -4, 9.83903751718671509455e-02L),
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u6u = LD80C(0xff636a8bdce7025b, -9, 3.89691687802305743450e-03L),
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v1u = LD80C(0xbd109c533a19fbf5, 1, 2.95413883330948556544e+00L),
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v2u = LD80C(0xd295cbf96f31f099, 1, 3.29039286955665403176e+00L),
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v3u = LD80C(0xdab8bcfee40496cb, 0, 1.70876276441416471410e+00L),
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v4u = LD80C(0xd2f2dc3638567e9f, -2, 4.12009126299534668571e-01L),
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v5u = LD80C(0xa07d9b0851070f41, -5, 3.91822868305682491442e-02L),
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v6u = LD80C(0xe3cd8318f7adb2c4, -11, 8.68998648222144351114e-04L);
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#define u0 (u0u.e)
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#define u1 (u1u.e)
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#define u2 (u2u.e)
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#define u3 (u3u.e)
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#define u4 (u4u.e)
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#define u5 (u5u.e)
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#define u6 (u6u.e)
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#define v1 (v1u.e)
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#define v2 (v2u.e)
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#define v3 (v3u.e)
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#define v4 (v4u.e)
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#define v5 (v5u.e)
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#define v6 (v6u.e)
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/*
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* Domain x in (2, 3], range ~[-3.3648e-22, 3.4416e-22]:
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* |(lgamma(y+2) - 0.5 * y) / y - s(y)/r(y)| < 2**-72.3
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* with y = x - 2.
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*/
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static const union IEEEl2bits
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s0u = LD80C(0x9e233f1bed863d27, -4, -7.72156649015328606095e-02L),
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s1u = LD80C(0xd3ff0dcc7fa91f94, -3, 2.07027640921219389860e-01L),
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s2u = LD80C(0xb2bb62782478ef31, -2, 3.49085881391362090549e-01L),
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s3u = LD80C(0xb49f7438c4611a74, -3, 1.76389518704213357954e-01L),
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s4u = LD80C(0x9a957008fa27ecf9, -5, 3.77401710862930008071e-02L),
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s5u = LD80C(0xda9b389a6ca7a7ac, -9, 3.33566791452943399399e-03L),
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s6u = LD80C(0xbc7a2263faf59c14, -14, 8.98728786745638844395e-05L),
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r1u = LD80C(0xbf5cff5b11477d4d, 0, 1.49502555796294337722e+00L),
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r2u = LD80C(0xd9aec89de08e3da6, -1, 8.50323236984473285866e-01L),
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r3u = LD80C(0xeab7ae5057c443f9, -3, 2.29216312078225806131e-01L),
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r4u = LD80C(0xf29707d9bd2b1e37, -6, 2.96130326586640089145e-02L),
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r5u = LD80C(0xd376c2f09736c5a3, -10, 1.61334161411590662495e-03L),
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r6u = LD80C(0xc985983d0cd34e3d, -16, 2.40232770710953450636e-05L),
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r7u = LD80C(0xe5c7a4f7fc2ef13d, -25, -5.34997929289167573510e-08L);
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#define s0 (s0u.e)
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#define s1 (s1u.e)
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#define s2 (s2u.e)
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#define s3 (s3u.e)
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#define s4 (s4u.e)
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#define s5 (s5u.e)
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#define s6 (s6u.e)
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#define r1 (r1u.e)
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#define r2 (r2u.e)
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#define r3 (r3u.e)
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#define r4 (r4u.e)
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#define r5 (r5u.e)
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#define r6 (r6u.e)
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#define r7 (r7u.e)
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/*
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* Domain z in [8, 0x1p70], range ~[-3.0235e-22, 3.0563e-22]:
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* |lgamma(x) - (x - 0.5) * (log(x) - 1) - w(1/x)| < 2**-71.7
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*/
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static const union IEEEl2bits
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w0u = LD80C(0xd67f1c864beb4a69, -2, 4.18938533204672741776e-01L),
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w1u = LD80C(0xaaaaaaaaaaaaaaa1, -4, 8.33333333333333332678e-02L),
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w2u = LD80C(0xb60b60b60b5491c9, -9, -2.77777777777760927870e-03L),
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w3u = LD80C(0xd00d00cf58aede4c, -11, 7.93650793490637233668e-04L),
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w4u = LD80C(0x9c09bf626783d4a5, -11, -5.95238023926039051268e-04L),
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w5u = LD80C(0xdca7cadc5baa517b, -11, 8.41733700408000822962e-04L),
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w6u = LD80C(0xfb060e361e1ffd07, -10, -1.91515849570245136604e-03L),
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w7u = LD80C(0xcbd5101bb58d1f2b, -8, 6.22046743903262649294e-03L),
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w8u = LD80C(0xad27a668d32c821b, -6, -2.11370706734662081843e-02L);
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#define w0 (w0u.e)
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#define w1 (w1u.e)
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#define w2 (w2u.e)
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#define w3 (w3u.e)
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#define w4 (w4u.e)
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#define w5 (w5u.e)
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#define w6 (w6u.e)
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#define w7 (w7u.e)
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#define w8 (w8u.e)
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static long double
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sin_pil(long double x)
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{
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volatile long double vz;
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long double y,z;
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uint64_t n;
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uint16_t hx;
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y = -x;
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vz = y+0x1p63;
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z = vz-0x1p63;
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if (z == y)
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return zero;
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vz = y+0x1p61;
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EXTRACT_LDBL80_WORDS(hx,n,vz);
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z = vz-0x1p61;
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if (z > y) {
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z -= 0.25; /* adjust to round down */
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n--;
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}
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n &= 7; /* octant of y mod 2 */
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y = y - z + n * 0.25; /* y mod 2 */
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switch (n) {
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case 0: y = __kernel_sinl(pi*y,zero,0); break;
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case 1:
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case 2: y = __kernel_cosl(pi*(0.5-y),zero); break;
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case 3:
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case 4: y = __kernel_sinl(pi*(one-y),zero,0); break;
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case 5:
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case 6: y = -__kernel_cosl(pi*(y-1.5),zero); break;
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default: y = __kernel_sinl(pi*(y-2.0),zero,0); break;
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}
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return -y;
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}
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long double
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lgammal_r(long double x, int *signgamp)
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{
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long double nadj,p,p1,p2,q,r,t,w,y,z;
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uint64_t lx;
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int i;
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uint16_t hx,ix;
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EXTRACT_LDBL80_WORDS(hx,lx,x);
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/* purge +-Inf and NaNs */
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*signgamp = 1;
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ix = hx&0x7fff;
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if(ix==0x7fff) return x*x;
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ENTERI();
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/* purge +-0 and tiny arguments */
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*signgamp = 1-2*(hx>>15);
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if(ix<0x3fff-67) { /* |x|<2**-(p+3), return -log(|x|) */
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if((ix|lx)==0)
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RETURNI(one/vzero);
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RETURNI(-logl(fabsl(x)));
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}
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/* purge negative integers and start evaluation for other x < 0 */
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if(hx&0x8000) {
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*signgamp = 1;
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if(ix>=0x3fff+63) /* |x|>=2**(p-1), must be -integer */
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RETURNI(one/vzero);
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t = sin_pil(x);
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if(t==zero) RETURNI(one/vzero); /* -integer */
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nadj = logl(pi/fabsl(t*x));
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if(t<zero) *signgamp = -1;
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x = -x;
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}
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/* purge 1 and 2 */
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if((ix==0x3fff || ix==0x4000) && lx==0x8000000000000000ULL) r = 0;
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/* for x < 2.0 */
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else if(ix<0x4000) {
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/*
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* XXX Supposedly, one can use the following information to replace the
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* XXX FP rational expressions. A similar approach is appropriate
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* XXX for ld128, but one (may need?) needs to consider llx, too.
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*
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* 8.9999961853027344e-01 3ffe e666600000000000
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* 7.3159980773925781e-01 3ffe bb4a200000000000
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* 2.3163998126983643e-01 3ffc ed33080000000000
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* 1.7316312789916992e+00 3fff dda6180000000000
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* 1.2316322326660156e+00 3fff 9da6200000000000
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*/
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if(x<8.9999961853027344e-01) {
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r = -logl(x);
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if(x>=7.3159980773925781e-01) {y = 1-x; i= 0;}
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else if(x>=2.3163998126983643e-01) {y= x-(tc-1); i=1;}
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else {y = x; i=2;}
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} else {
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r = 0;
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if(x>=1.7316312789916992e+00) {y=2-x;i=0;}
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else if(x>=1.2316322326660156e+00) {y=x-tc;i=1;}
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else {y=x-1;i=2;}
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}
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switch(i) {
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case 0:
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z = y*y;
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p1 = a0+z*(a2+z*(a4+z*(a6+z*(a8+z*(a10+z*a12)))));
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p2 = z*(a1+z*(a3+z*(a5+z*(a7+z*(a9+z*(a11+z*a13))))));
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p = y*p1+p2;
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r += p-y/2; break;
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case 1:
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p = t0+y*t1+tt+y*y*(t2+y*(t3+y*(t4+y*(t5+y*(t6+y*(t7+y*(t8+
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y*(t9+y*(t10+y*(t11+y*(t12+y*(t13+y*(t14+y*(t15+y*(t16+
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y*(t17+y*t18))))))))))))))));
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r += tf + p; break;
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case 2:
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p1 = y*(u0+y*(u1+y*(u2+y*(u3+y*(u4+y*(u5+y*u6))))));
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p2 = 1+y*(v1+y*(v2+y*(v3+y*(v4+y*(v5+y*v6)))));
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r += p1/p2-y/2;
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}
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}
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/* x < 8.0 */
|
|
else if(ix<0x4002) {
|
|
i = x;
|
|
y = x-i;
|
|
p = y*(s0+y*(s1+y*(s2+y*(s3+y*(s4+y*(s5+y*s6))))));
|
|
q = 1+y*(r1+y*(r2+y*(r3+y*(r4+y*(r5+y*(r6+y*r7))))));
|
|
r = y/2+p/q;
|
|
z = 1; /* lgamma(1+s) = log(s) + lgamma(s) */
|
|
switch(i) {
|
|
case 7: z *= (y+6); /* FALLTHRU */
|
|
case 6: z *= (y+5); /* FALLTHRU */
|
|
case 5: z *= (y+4); /* FALLTHRU */
|
|
case 4: z *= (y+3); /* FALLTHRU */
|
|
case 3: z *= (y+2); /* FALLTHRU */
|
|
r += logl(z); break;
|
|
}
|
|
/* 8.0 <= x < 2**(p+3) */
|
|
} else if (ix<0x3fff+67) {
|
|
t = logl(x);
|
|
z = one/x;
|
|
y = z*z;
|
|
w = w0+z*(w1+y*(w2+y*(w3+y*(w4+y*(w5+y*(w6+y*(w7+y*w8)))))));
|
|
r = (x-half)*(t-one)+w;
|
|
/* 2**(p+3) <= x <= inf */
|
|
} else
|
|
r = x*(logl(x)-1);
|
|
if(hx&0x8000) r = nadj - r;
|
|
RETURNI(r);
|
|
}
|