A variant of atan.
Converts both arguments to doubles.
Returns the angle in radians between the positive x-axis
and the vector (
The result is in the range -PI..PI.
b is positive, this is the same as
The result is negative when
a is negative (including when
a is the
a is equal to zero, the vector (
a) is considered parallel to
the x-axis, even if
b is also equal to zero. The sign of
the direction of the vector along the x-axis.
Returns NaN if either argument is NaN.
external double atan2(num a, num b);