acos(3)
NAME
acos, acosf, acosl - arc cosine function
SYNOPSIS
#include <math.h> double acos(double x); float acosf(float x); long double acosl(long double x); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): acosf(), acosl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
DESCRIPTION
The acos() function calculates the arc cosine of x; that is the value
whose cosine is x.
RETURN VALUE
On success, these functions return the arc cosine of x in radians; the
return value is in the range [0, pi].
If x is a NaN, a NaN is returned.
If x is +1, +0 is returned.
If x is positive infinity or negative infinity, a domain error occurs,
and a NaN is returned.
If x is outside the range [-1, 1], a domain error occurs, and a NaN is
returned.
ERRORS
See math_error(7) for information on how to determine whether an error
has occurred when calling these functions.
The following errors can occur:
- Domain error: x is outside the range [-1, 1]
- errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.
CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
4.3BSD, C89.
SEE ALSO
asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)
COLOPHON
- This page is part of release 3.25 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.