Hi,

In message "[ruby-talk:01288] Bug in doc for atan2?"
    on 00/02/09, Andrew Hunt <Andy / Toolshed.Com> writes:

|The source for Math.atan2 documents its parameters as (x, y), as does
|the Japanese Ruby book (pg 504).  However, the atan2 function takes
|its arguments as (y, x) according to the Unix man pages and the Java
|documentation (which is based netlib's math library).
|
|I'm assuming it should be atan2(y,x), right?

Right, it was documentation bug.