atan2
See the current Perl documentation for atan2.
Here is our local, out-dated (pre-5.6) version:
atan2 - arctangent of Y/X
atan2 Y,X
Returns the arctangent of Y/X in the range -PI to PI.
For the tangent operation, you may use the POSIX::tan()
function, or use the familiar relation:
sub tan { sin($_[0]) / cos($_[0]) }