atan package:copilot-language

a version of arctangent taking two real floating-point arguments. For real floating x and y, atan2 y x computes the angle (from the positive x-axis) of the vector from the origin to the point (x,y). atan2 y x returns a value in the range [-pi, pi]. It follows the Common Lisp semantics for the origin when signed zeroes are supported. atan2 y 1, with y in a type that is RealFloat, should return the same value as atan y. A default definition of atan2 is provided, but implementors can provide a more accurate implementation.

Point-wise application of atan2 to the values of two streams. For each pair of real floating-point samples x and y, one from each stream, atan2 computes the angle of the vector from (0, 0) to the point (x, y). This definition clashes with one in RealFloat in Haskell's Prelude, re-exported from Language.Copilot, so you need to import this module qualified to use this function.