Documentation for routine
atan2 assembled from the following types:
method atan2( = 1e0)
say 3.atan2; # OUTPUT: «1.24904577239825␤»say ⅔.atan2(⅓); # OUTPUT: «1.1071487177940904␤»
The first argument defaults to 1, so in the first case the function will return the angle θ in radians between a vector that goes from origin to the point (3, 1) and the x axis.