atan
(PHP 3, PHP 4 , PHP 5)
atan -- Arc tangent
Description
float
atan ( float arg)
Returns the arc tangent of arg in radians. atan() is the complementary function of tan(), which means that a==tan(atan(a)) for every value of a that is within atan()'s range.
Смотрите также: atanh(), asin(), and acos().