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Add cosh optimized for 64-bit architectures

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Ulrich Drepper 2011-10-15 20:47:01 -04:00
parent bcf01e6d80
commit b61099b50a
3 changed files with 85 additions and 4 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2011-10-15 Ulrich Drepper <drepper@gmail.com>
* sysdeps/ieee754/dbl-64/e_cosh.c: Cleanup.
* sysdeps/ieee754/dbl-64/wordsize-64/e_cosh.c: New file.
* math/Versions [libm] (GLIBC_2.15): Add __exp_finite, __expf_finite,
__expl_finite.
* math/bits/math-finite.h: Add entries for exp.

4
sysdeps/ieee754/dbl-64/e_cosh.c
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@ -10,10 +10,6 @@
* ====================================================
*/
#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: e_cosh.c,v 1.7 1995/05/10 20:44:58 jtc Exp $";
#endif
/* __ieee754_cosh(x)
* Method :
* mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2

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sysdeps/ieee754/dbl-64/wordsize-64/e_cosh.c Normal file
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/* Optimized by Ulrich Drepper <drepper@gmail.com>, 2011 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/* __ieee754_cosh(x)
* Method :
* mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2
* 1. Replace x by |x| (cosh(x) = cosh(-x)).
* 2.
* [ exp(x) - 1 ]^2
* 0 <= x <= ln2/2 : cosh(x) := 1 + -------------------
* 2*exp(x)
*
* exp(x) + 1/exp(x)
* ln2/2 <= x <= 22 : cosh(x) := -------------------
* 2
* 22 <= x <= lnovft : cosh(x) := exp(x)/2
* lnovft <= x <= ln2ovft: cosh(x) := exp(x/2)/2 * exp(x/2)
* ln2ovft < x : cosh(x) := huge*huge (overflow)
*
* Special cases:
* cosh(x) is |x| if x is +INF, -INF, or NaN.
* only cosh(0)=1 is exact for finite x.
*/
#include "math.h"
#include "math_private.h"
static const double one = 1.0, half=0.5, huge = 1.0e300;
double
__ieee754_cosh (double x)
{
double t,w;
int32_t ix;
/* High word of |x|. */
GET_HIGH_WORD(ix,x);
ix &= 0x7fffffff;
/* |x| in [0,22] */
if (ix < 0x40360000) {
/* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
if(ix<0x3fd62e43) {
t = __expm1(fabs(x));
w = one+t;
if (ix<0x3c800000) return w; /* cosh(tiny) = 1 */
return one+(t*t)/(w+w);
}
/* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
t = __ieee754_exp(fabs(x));
return half*t+half/t;
}
/* |x| in [22, log(maxdouble)] return half*exp(|x|) */
if (ix < 0x40862e42) return half*__ieee754_exp(fabs(x));
/* |x| in [log(maxdouble), overflowthresold] */
int64_t fix;
EXTRACT_WORDS64(fix, x);
if (fix <= UINT64_C(0x408633ce8fb9f87d)) {
w = __ieee754_exp(half*fabs(x));
t = half*w;
return t*w;
}
/* x is INF or NaN */
if(ix>=0x7ff00000) return x*x;
/* |x| > overflowthresold, cosh(x) overflow */
return huge*huge;
}
strong_alias (__ieee754_cosh, __cosh_finite)