cljs.math/atan2

functionsince v1.11.50Edit
(atan2 y x)

Source docstring:
Returns the angle theta from the conversion of rectangular coordinates (x, y) to polar coordinates (r, theta).
Computes the phase theta by computing an arc tangent of y/x in the range of -pi to pi.
For more details on special cases, see:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/atan
Source code @ clojurescript:src/main/cljs/cljs/math.cljs
(defn ^number atan2
  {:added "1.11.10"}
  [y x] (Math/atan2 y x))