mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-23 13:30:06 +00:00
62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
/* e_acoshl.c -- long double version of e_acosh.c.
|
|
* Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz.
|
|
*/
|
|
|
|
/*
|
|
* ====================================================
|
|
* 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_acoshl(x)
|
|
* Method :
|
|
* Based on
|
|
* acoshl(x) = logl [ x + sqrtl(x*x-1) ]
|
|
* we have
|
|
* acoshl(x) := logl(x)+ln2, if x is large; else
|
|
* acoshl(x) := logl(2x-1/(sqrtl(x*x-1)+x)) if x>2; else
|
|
* acoshl(x) := log1pl(t+sqrtl(2.0*t+t*t)); where t=x-1.
|
|
*
|
|
* Special cases:
|
|
* acoshl(x) is NaN with signal if x<1.
|
|
* acoshl(NaN) is NaN without signal.
|
|
*/
|
|
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
static const long double
|
|
one = 1.0,
|
|
ln2 = 0.6931471805599453094172321214581766L;
|
|
|
|
long double
|
|
__ieee754_acoshl(long double x)
|
|
{
|
|
long double t;
|
|
u_int64_t lx;
|
|
int64_t hx;
|
|
GET_LDOUBLE_WORDS64(hx,lx,x);
|
|
if(hx<0x3fff000000000000LL) { /* x < 1 */
|
|
return (x-x)/(x-x);
|
|
} else if(hx >=0x4035000000000000LL) { /* x > 2**54 */
|
|
if(hx >=0x7fff000000000000LL) { /* x is inf of NaN */
|
|
return x+x;
|
|
} else
|
|
return __ieee754_logl(x)+ln2; /* acoshl(huge)=logl(2x) */
|
|
} else if(((hx-0x3fff000000000000LL)|lx)==0) {
|
|
return 0.0L; /* acosh(1) = 0 */
|
|
} else if (hx > 0x4000000000000000LL) { /* 2**28 > x > 2 */
|
|
t=x*x;
|
|
return __ieee754_logl(2.0L*x-one/(x+__ieee754_sqrtl(t-one)));
|
|
} else { /* 1<x<2 */
|
|
t = x-one;
|
|
return __log1pl(t+__sqrtl(2.0L*t+t*t));
|
|
}
|
|
}
|
|
strong_alias (__ieee754_acoshl, __acoshl_finite)
|