NAME

asin - arc sine function

 SYNOPSIS

#include <math.h>

double asin(double x);

 DESCRIPTION

The asin() function computes the principal value of the arc sine of x. The value of x should be in the range [-1,1].

An application wishing to check for error situations should set errno to 0, then call asin(). If errno is non-zero on return, or the return value is NaN, an error has occurred.

 RETURN VALUE

Upon successful completion, asin() returns the arc sine of x, in the range [-/2, /2] radians. If the value of x is not in the range [-1,1], and is not ±Inf or NaN, either 0.0 or NaN is returned and errno is set to [EDOM].

If x is NaN, NaN is returned and errno may be set to [EDOM].

If x is ±Inf, either 0.0 is returned and errno is set to [EDOM] or NaN is returned and errno may be set to [EDOM].

If the result underflows, 0.0 is returned and errno may be set to [ERANGE].

 ERRORS

The asin() function will fail if:

[EDOM]

The value x is not ±Inf or NaN and is not in the range [-1,1].

The asin() function may fail if:

[EDOM]

The value of x is ±Inf or NaN.

[ERANGE]

The result underflows.

No other errors will occur.

 EXAMPLES

None.

 APPLICATION USAGE

None.

 FUTURE DIRECTIONS

None.

 SEE ALSO

isnan(), sin(), <math.h>.

DERIVATION

Derived from Issue 1 of the SVID.