# routine atan2

Documentation for routine `atan2`

assembled from the following types:

# class Cool

From Cool

## (Cool) routine atan2

Defined as:

sub atan2(, = 1e0)method atan2( = 1e0)

The sub should usually be written with two arguments for clarity as it is seen in other languages and in mathematical texts, but the single-argument form is available; its result will always match that of atan.

say atan2 3, 1; # OUTPUT: «1.2490457723982544»say atan2 3; # OUTPUT: «1.2490457723982544»say atan2 ⅔, ⅓; # OUTPUT: «1.1071487177940904»

The method coerces self and its single argument to Numeric, using them to compute the two-argument arc-tangent in radians.

say 3.atan2; # OUTPUT: «1.24904577239825»say ⅔.atan2(⅓); # OUTPUT: «1.1071487177940904»

The $x argument in either the method or the sub defaults to 1 so, in both single-argument cases, the function will return the angle θ in radians between the x-axis and a vector that goes from the origin to the point (3, 1).