2000-02-18 03:39:52 +08:00
|
|
|
|
|
|
|
/* @(#)w_acos.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.
|
|
|
|
* ====================================================
|
|
|
|
*/
|
|
|
|
|
|
|
|
/*
|
|
|
|
FUNCTION
|
|
|
|
<<acos>>, <<acosf>>---arc cosine
|
|
|
|
|
|
|
|
INDEX
|
|
|
|
acos
|
|
|
|
INDEX
|
|
|
|
acosf
|
|
|
|
|
|
|
|
ANSI_SYNOPSIS
|
|
|
|
#include <math.h>
|
|
|
|
double acos(double <[x]>);
|
|
|
|
float acosf(float <[x]>);
|
|
|
|
|
|
|
|
TRAD_SYNOPSIS
|
|
|
|
#include <math.h>
|
|
|
|
double acos(<[x]>)
|
|
|
|
double <[x]>;
|
|
|
|
|
|
|
|
float acosf(<[x]>)
|
|
|
|
float <[x]>;
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
DESCRIPTION
|
|
|
|
|
|
|
|
<<acos>> computes the inverse cosine (arc cosine) of the input value.
|
|
|
|
Arguments to <<acos>> must be in the range @minus{}1 to 1.
|
|
|
|
|
|
|
|
<<acosf>> is identical to <<acos>>, except that it performs
|
|
|
|
its calculations on <<floats>>.
|
|
|
|
|
|
|
|
RETURNS
|
2003-10-21 02:46:38 +08:00
|
|
|
@ifnottex
|
2000-02-18 03:39:52 +08:00
|
|
|
<<acos>> and <<acosf>> return values in radians, in the range of 0 to pi.
|
2003-10-21 02:46:38 +08:00
|
|
|
@end ifnottex
|
2000-02-18 03:39:52 +08:00
|
|
|
@tex
|
|
|
|
<<acos>> and <<acosf>> return values in radians, in the range of <<0>> to $\pi$.
|
|
|
|
@end tex
|
|
|
|
|
|
|
|
If <[x]> is not between @minus{}1 and 1, the returned value is NaN
|
|
|
|
(not a number) the global variable <<errno>> is set to <<EDOM>>, and a
|
|
|
|
<<DOMAIN error>> message is sent as standard error output.
|
|
|
|
|
|
|
|
You can modify error handling for these functions using <<matherr>>.
|
|
|
|
|
|
|
|
|
|
|
|
QUICKREF ANSI SVID POSIX RENTRANT
|
|
|
|
acos y,y,y,m
|
|
|
|
acosf n,n,n,m
|
|
|
|
|
|
|
|
MATHREF
|
|
|
|
acos, [-1,1], acos(arg),,,
|
|
|
|
acos, NAN, arg,DOMAIN,EDOM
|
|
|
|
|
|
|
|
MATHREF
|
|
|
|
acosf, [-1,1], acosf(arg),,,
|
|
|
|
acosf, NAN, argf,DOMAIN,EDOM
|
|
|
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
/*
|
|
|
|
* wrap_acos(x)
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include "fdlibm.h"
|
|
|
|
#include <errno.h>
|
|
|
|
|
|
|
|
#ifndef _DOUBLE_IS_32BITS
|
|
|
|
|
|
|
|
#ifdef __STDC__
|
|
|
|
double acos(double x) /* wrapper acos */
|
|
|
|
#else
|
|
|
|
double acos(x) /* wrapper acos */
|
|
|
|
double x;
|
|
|
|
#endif
|
|
|
|
{
|
|
|
|
#ifdef _IEEE_LIBM
|
|
|
|
return __ieee754_acos(x);
|
|
|
|
#else
|
|
|
|
double z;
|
|
|
|
struct exception exc;
|
|
|
|
z = __ieee754_acos(x);
|
|
|
|
if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
|
|
|
|
if(fabs(x)>1.0) {
|
|
|
|
/* acos(|x|>1) */
|
|
|
|
exc.type = DOMAIN;
|
|
|
|
exc.name = "acos";
|
|
|
|
exc.err = 0;
|
|
|
|
exc.arg1 = exc.arg2 = x;
|
|
|
|
exc.retval = 0.0;
|
|
|
|
if (_LIB_VERSION == _POSIX_)
|
|
|
|
errno = EDOM;
|
|
|
|
else if (!matherr(&exc)) {
|
|
|
|
errno = EDOM;
|
|
|
|
}
|
|
|
|
if (exc.err != 0)
|
|
|
|
errno = exc.err;
|
|
|
|
return exc.retval;
|
|
|
|
} else
|
|
|
|
return z;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
|
|
|
|
#endif /* defined(_DOUBLE_IS_32BITS) */
|