asin - arc sine function
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.
The asin() function returns the arc sine in radians
and the value is mathematically defined to be between -PI/2
and PI/2 (inclusive).
x is out of range.
SVID 3, POSIX, BSD 4.3, ISO 9899
acos(3), atan(3), atan2(3),
cos(3), sin(3), tan(3)