Man page - acos(3)

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Manual

acos

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
STANDARDS
HISTORY
SEE ALSO

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 attributes (7).

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STANDARDS

C11, POSIX.1-2008.

HISTORY

C99, POSIX.1-2001.

The variant returning double also conforms to C89, SVr4, 4.3BSD.

SEE ALSO

asin (3), atan (3), atan2 (3), cacos (3), cos (3), sin (3), tan (3)