asin(3)

NAME
asin, asinf, asinl - arc sine function

LIBRARY
Math library (libm, -lm)

SYNOPSIS
#include <math.h>

double asin(double x);
float asinf(float x);
long double asinl(long double x);

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

asinf(), asinl():
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
These functions calculate 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).
Interface | Attribute | Value
 | Thread safety | MT-Safe

STANDARDS
C11, POSIX.1-2008.

HISTORY
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)