ACOS
Section: Linux Programmer's Manual (3)
Updated: 2010-09-20
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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 ||
_POSIX_C_SOURCE >= 200112L;
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)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- SEE ALSO
-
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