atan() - math

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.

Parameters : 
 arg - The argument to process 

Syntax

float atan
     ( float $arg
    )

Example

Output / Return Value

Limitations

Alternatives / See Also

Reference