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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | SEE ALSO | COLOPHON |
ACOS(3) Linux Programmer's Manual ACOS(3)
acos, acosf, acosl - arc cosine function
#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():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
These functions calculate the arc cosine of x; that is the value
whose cosine is x.
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.
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.
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├─────────────────────────┼───────────────┼─────────┤
│acos(), acosf(), acosl() │ Thread safety │ MT-Safe │
└─────────────────────────┴───────────────┴─────────┘
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)
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latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2016-03-15 ACOS(3)
Pages that refer to this page: asin(3), atan2(3), atan(3), cos(3), sin(3), tan(3)