94 lines
1.8 KiB
C
94 lines
1.8 KiB
C
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/* @(#)z_acos.c 1.0 98/08/13 */
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/*
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FUNCTION
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<<acos>>, <<acosf>>---arc cosine
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INDEX
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acos
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INDEX
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acosf
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ANSI_SYNOPSIS
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#include <math.h>
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double acos(double <[x]>);
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float acosf(float <[x]>);
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TRAD_SYNOPSIS
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#include <math.h>
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double acos(<[x]>)
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double <[x]>;
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float acosf(<[x]>)
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float <[x]>;
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DESCRIPTION
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<<acos>> computes the inverse cosine (arc cosine) of the input value.
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Arguments to <<acos>> must be in the range @minus{}1 to 1.
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<<acosf>> is identical to <<acos>>, except that it performs
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its calculations on <<floats>>.
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RETURNS
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@ifinfo
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<<acos>> and <<acosf>> return values in radians, in the range of 0 to pi
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.
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@end ifinfo
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@tex
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<<acos>> and <<acosf>> return values in radians, in the range of <<0>> t
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o $\pi$.
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@end tex
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If <[x]> is not between @minus{}1 and 1, the returned value is NaN
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(not a number) the global variable <<errno>> is set to <<EDOM>>, and a
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<<DOMAIN error>> message is sent as standard error output.
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You can modify error handling for these functions using <<matherr>>.
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QUICKREF ANSI SVID POSIX RENTRANT
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acos y,y,y,m
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acosf n,n,n,m
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MATHREF
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acos, [-1,1], acos(arg),,,
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acos, NAN, arg,DOMAIN,EDOM
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MATHREF
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acosf, [-1,1], acosf(arg),,,
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acosf, NAN, argf,DOMAIN,EDOM
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*/
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/*****************************************************************
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* Arccosine
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*
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* Input:
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* x - floating point value
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*
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* Output:
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* arccosine of x
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*
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* Description:
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* This routine returns the arccosine of x.
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*
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*****************************************************************/
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#include "fdlibm.h"
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#include "zmath.h"
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#ifndef _DOUBLE_IS_32BITS
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double
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_DEFUN (acos, (double),
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double x)
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{
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return (asine (x, 1));
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}
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#endif /* _DOUBLE_IS_32BITS */
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