-- Perl 5.10.0 documentation --
atan2
Perl functions A-Z | Perl functions by category | The 'perlfunc' manpage
  • atan2 Y,X

    Returns the arctangent of Y/X in the range -PI to PI.

    For the tangent operation, you may use the Math::Trig::tan function, or use the familiar relation:

        sub tan { sin($_[0]) / cos($_[0])  }

    Note that atan2(0, 0) is not well-defined.