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/* @(#)z_acos.c 1.0 98/08/13 */
/*
FUNCTION
<<acos>>, <<acosf>>---arc cosine
INDEX
acos
INDEX
acosf
SYNOPSIS
#include <math.h>
double acos(double <[x]>);
float acosf(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
@ifnottex
<<acos>> and <<acosf>> return values in radians, in the range of 0 to pi
.
@end ifnottex
@tex
<<acos>> and <<acosf>> return values in radians, in the range of <<0>> t
o $\pi$.
@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.
QUICKREF
ansi posix rentrant
acos y,y,m
acosf 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
*/
/*****************************************************************
* Arccosine
*
* Input:
* x - floating point value
*
* Output:
* arccosine of x
*
* Description:
* This routine returns the arccosine of x.
*
*****************************************************************/
#include "fdlibm.h"
#include "zmath.h"
#ifndef _DOUBLE_IS_32BITS
double
acos (double x)
{
return (asine (x, 1));
}
#endif /* _DOUBLE_IS_32BITS */
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