ACOS(3) BSD Programmer's Manual ACOS(3)NAME
acos, acosf - arc cosine functions
SYNOPSIS
#include <math.h>
double
acos(double x);
float
acosf(float x);
DESCRIPTION
The acos() and the acosf() functions compute the principal value of the
arc cosine of x in the range [0, pi] radians. For a discussion of error
reporting, see math(3).
ERRORS
If |x| > 1 then:
_IEEE_ The return value is NaN.
_POSIX_ The return value is 0, and errno is set to EDOM.
_XOPEN_ Same as _POSIX_, but errno is only set if matherr(3) returns 0.
The exception type is DOMAIN.
_SVID_ Same as _XOPEN_, and a message is printed to stderr if errno is
set.
SEE ALSOasin(3), atan(3), atan2(3), cos(3), cosh(3), math(3), sin(3),
sinh(3), tan(3), tanh(3)STANDARDS
The acos() function conforms to ANSI C X3.159-1989 (``ANSI C '').
BSDI BSD/OS February 17, 1998 1