Synopsis
#include <math.h>
double asin(double x);
Description
asin returns the principal value, in radians, of the inverse circular sine of x. The principal value lies in the interval [-PI/2, +PI/2] radians.
Fast math library behavior
If |x| > 1, errno is set to EDOM and asin returns HUGE_VAL.
IEC 60559 math library behavior
If x is NaN, asin returns x.
If |x| > 1, asin returns NaN with invalid signal.
Portability
asin conforms to ISO/IEC 9899:1990 (C90) and ISO/IEC 9899:1999 (C99).