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.

See also: atanh(), asin(), and acos().