0cbb654791
zero, one, two, half are replaced by const literals The policy was to use the f suffix for float consts (1.0f), but don't use suffix for long double consts (these consts can be exactly represented as double).
59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
/* origin: OpenBSD /usr/src/lib/libm/src/ld80/e_acoshl.c */
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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 SunPro, 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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/* acoshl(x)
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* Method :
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* Based on
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* acoshl(x) = logl [ x + sqrtl(x*x-1) ]
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* we have
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* acoshl(x) := logl(x)+ln2, if x is large; else
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* acoshl(x) := logl(2x-1/(sqrtl(x*x-1)+x)) if x>2; else
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* acoshl(x) := log1pl(t+sqrtl(2.0*t+t*t)); where t=x-1.
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*
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* Special cases:
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* acoshl(x) is NaN with signal if x<1.
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* acoshl(NaN) is NaN without signal.
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*/
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#include "libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double acoshl(long double x)
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{
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return acosh(x);
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}
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#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
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static const long double
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ln2 = 6.931471805599453094287e-01L; /* 0x3FFE, 0xB17217F7, 0xD1CF79AC */
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long double acoshl(long double x)
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{
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long double t;
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uint32_t se,i0,i1;
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GET_LDOUBLE_WORDS(se, i0, i1, x);
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if (se < 0x3fff || se & 0x8000) { /* x < 1 */
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return (x-x)/(x-x);
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} else if (se >= 0x401d) { /* x > 2**30 */
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if (se >= 0x7fff) /* x is inf or NaN */
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return x+x;
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return logl(x) + ln2; /* acoshl(huge) = logl(2x) */
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} else if (((se-0x3fff)|i0|i1) == 0) {
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return 0.0; /* acosh(1) = 0 */
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} else if (se > 0x4000) { /* x > 2 */
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t = x*x;
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return logl(2.0*x - 1.0/(x + sqrtl(t - 1.0)));
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}
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/* 1 < x <= 2 */
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t = x - 1.0;
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return log1pl(t + sqrtl(2.0*t + t*t));
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}
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#endif
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