=over
=item atan2 Y,X
X X X X
Returns the arctangent of Y/X in the range -PI to PI.
For the tangent operation, you may use the
L|Math::Trig/B> function, or use the familiar
relation:
sub tan { sin($_[0]) / cos($_[0]) }
The return value for C is implementation-defined; consult
your L manpage for more information.
Portability issues: L.
=back