diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/e_acoshl.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/e_acoshl.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c b/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c new file mode 100644 index 0000000000..00576c76c8 --- /dev/null +++ b/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c @@ -0,0 +1,69 @@ +/* @(#)e_acosh.c 5.1 93/09/24 */ +/* + * ==================================================== + * 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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: e_acosh.c,v 1.9 1995/05/12 04:57:18 jtc Exp $"; +#endif + +/* __ieee754_acosh(x) + * Method : + * Based on + * acosh(x) = log [ x + sqrt(x*x-1) ] + * we have + * acosh(x) := log(x)+ln2, if x is large; else + * acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else + * acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1. + * + * Special cases: + * acosh(x) is NaN with signal if x<1. + * acosh(NaN) is NaN without signal. + */ + +#include "math.h" +#include "math_private.h" + +#ifdef __STDC__ +static const long double +#else +static long double +#endif +one = 1.0L, +ln2 = 6.93147180559945286227e-01L; /* 0x3FE62E42, 0xFEFA39EF */ + +#ifdef __STDC__ + long double __ieee754_acoshl(long double x) +#else + long double __ieee754_acoshl(x) + long double x; +#endif +{ + long double t; + int64_t hx; + u_int64_t lx; + GET_LDOUBLE_WORDS64(hx,lx,x); + if(hx<0x3ff0000000000000LL) { /* x < 1 */ + return (x-x)/(x-x); + } else if(hx >=0x41b0000000000000LL) { /* x > 2**28 */ + if(hx >=0x7ff0000000000000LL) { /* x is inf of NaN */ + return x+x; + } else + return __ieee754_logl(x)+ln2; /* acosh(huge)=log(2x) */ + } else if (((hx-0x3ff0000000000000LL)|(lx&0x7fffffffffffffffLL))==0) { + return 0.0; /* acosh(1) = 0 */ + } else if (hx > 0x4000000000000000LL) { /* 2**28 > x > 2 */ + t=x*x; + return __ieee754_logl(2.0*x-one/(x+__ieee754_sqrtl(t-one))); + } else { /* 1<x<2 */ + t = x-one; + return __log1p(t+__sqrtl(2.0*t+t*t)); + } +} |