asin
(PHP 3, PHP 4 , PHP 5)
asin -- Arc sine
Description
float
asin ( float arg )
Returns the arc sine of arg in radians.
asin() is the complementary function of
sin(), which means that
a==sin(asin(a)) for every value of a that is within
asin()'s range.
See also:
asinh(),
acos(), and
atan().