libc/newlib/libm/math/e_sinh.c
Jeff Johnston e0b0f63573 2000-08-23 Werner Almesberger <Werner.Almesberger@epfl.ch>
* libc/stdlib/mprec.c (ulp, b2d, d2b): changed a few expressions
        like  x << y-z  to the equivalent  x << (y-z).
        (d2b): changed if statements with assignment to perform the
        assignment prior to the if check.
        * libc/reent/reent.c: included stdlib.h for "_free_r" prototype.
        * libc/unix/getpass.c (getpass): moved "echo" assignment out of if.
        * libc/unix/ttyname.c: included string.h for "strcpy" prototype.
        * libc/unix/getcwd.c (ISDOT): added parentheses to clarify && and ||
        precedence.
        * libc/include/sys/unistd.h: added "vfork" prototype (for popen.c).
        Added "_execve" prototype (for execl.c, execle.c, execv.c, and
        execve.c).
        * libc/posix/popen.c (popen): added parentheses to clarify && and ||
        precedence.
        * libm/math/e_cosh.c (__ieee754_cosh): changed parentheses to
        clarify && and || precendence (and to remove pascalism).
        * libm/math/e_sinh.c (__ieee754_sinh): Ditto.
        * libm/math/s_infconst.c: added another pair of braces to all
        initializers for __infinity (need three: for __infinity[1] array,
        for union __dmath, and for i[2]).
2000-08-28 17:45:56 +00:00

87 lines
2.2 KiB
C

/* @(#)e_sinh.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.
* ====================================================
*/
/* __ieee754_sinh(x)
* Method :
* mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
* 1. Replace x by |x| (sinh(-x) = -sinh(x)).
* 2.
* E + E/(E+1)
* 0 <= x <= 22 : sinh(x) := --------------, E=expm1(x)
* 2
*
* 22 <= x <= lnovft : sinh(x) := exp(x)/2
* lnovft <= x <= ln2ovft: sinh(x) := exp(x/2)/2 * exp(x/2)
* ln2ovft < x : sinh(x) := x*shuge (overflow)
*
* Special cases:
* sinh(x) is |x| if x is +INF, -INF, or NaN.
* only sinh(0)=0 is exact for finite x.
*/
#include "fdlibm.h"
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
static const double one = 1.0, shuge = 1.0e307;
#else
static double one = 1.0, shuge = 1.0e307;
#endif
#ifdef __STDC__
double __ieee754_sinh(double x)
#else
double __ieee754_sinh(x)
double x;
#endif
{
double t,w,h;
__int32_t ix,jx;
__uint32_t lx;
/* High word of |x|. */
GET_HIGH_WORD(jx,x);
ix = jx&0x7fffffff;
/* x is INF or NaN */
if(ix>=0x7ff00000) return x+x;
h = 0.5;
if (jx<0) h = -h;
/* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
if (ix < 0x40360000) { /* |x|<22 */
if (ix<0x3e300000) /* |x|<2**-28 */
if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
t = expm1(fabs(x));
if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one));
return h*(t+t/(t+one));
}
/* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
if (ix < 0x40862E42) return h*__ieee754_exp(fabs(x));
/* |x| in [log(maxdouble), overflowthresold] */
GET_LOW_WORD(lx,x);
if (ix<0x408633CE || (ix==0x408633ce && lx<=(__uint32_t)0x8fb9f87d)) {
w = __ieee754_exp(0.5*fabs(x));
t = h*w;
return t*w;
}
/* |x| > overflowthresold, sinh(x) overflow */
return x*shuge;
}
#endif /* defined(_DOUBLE_IS_32BITS) */