# ASIN

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

CONFORMING TO

SEE ALSO

COLOPHON

## NAME

asin, asinf,
asinl − arc sine function

## SYNOPSIS

**#include
<math.h>**

**double
asin(double** *x***); **

float asinf(float *x***); **

long double asinl(long double *x***);**

Link with
*−lm*.

Feature Test
Macro Requirements for glibc (see
**feature_test_macros**(7)):

**asinf**(),
**asinl**():

_BSD_SOURCE || _SVID_SOURCE ||
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;

or *cc -std=c99*

## DESCRIPTION

The
**asin**() function calculates the principal value of the
arc sine of *x*; that is the value whose sine is
*x*.

## RETURN VALUE

On success,
these functions return the principal value of the arc sine
of *x* in radians; the return value is in the range
[−pi/2, pi/2].

If *x* is
a NaN, a NaN is returned.

If *x* is
+0 (−0), +0 (−0) 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).

## CONFORMING TO

C99,
POSIX.1-2001. The variant returning *double* also
conforms to SVr4, 4.3BSD, C89.

## SEE ALSO

**acos**(3),
**atan**(3), **atan2**(3), **casin**(3),
**cos**(3), **sin**(3), **tan**(3)

## COLOPHON

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