ASIN(3) Linux Programmer's Manual ASIN(3)
**NAME**
asin - arc sine function
**SYNOPSIS**
**#include** **<math.h>**
**double** **asin(double** *x***);**
**DESCRIPTION**
The **asin()** function calculates the arc sine of *x*; that is
the value whose sine is *x*. If *x* falls outside the range
-1 to 1, **asin()** fails and *errno* is set.
**RETURN** **VALUE**
The **asin()** function returns the arc sine in radians and
the value is mathematically defined to be between -PI/2
and PI/2 (inclusive).
**ERRORS**
**EDOM** *x* is out of range.
**CONFORMING** **TO**
SVID 3, POSIX, BSD 4.3, ISO 9899
**SEE** **ALSO**
**acos**(3), **atan**(3), **atan2**(3), **cos**(3), **sin**(3), **tan**(3)
June 8, 1993 1