acos(3) Library Functions Manual acos(3)
NAME
acos, acosf, acosl - arc cosine function
LIBRARY
Math library (libm, -lm)
SYNOPSIS
#include <math.h>
double acos(double x);
float acosf(float x);
long double acosl(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
acosf(), acosl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
These functions calculate 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.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│acos(), acosf(), acosl() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSO
asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)
Linux man-pages 6.03 2023-02-05 acos(3)
Generated by dwww version 1.15 on Wed Jun 26 18:13:34 CEST 2024.