acos
(PHP 4, PHP 5)
acos — Arc cosine
說明
float acos
( float $arg
)
Returns the arc cosine of arg in radians. acos() is the complementary function of cos(), which means that a==cos(acos(a)) for every value of a that is within acos()' range.
參數
- arg
-
The argument to process
Return值
The arc consine of arg in radians.