atan2(sin(x),cos(x)) achieves the same computation as
fabs(x,2*pi()). The manual warns that
fabs() can induce sampling issues; would the same issues apply to the atan2 version?
Warning is due to possible discontinuity in gradient. The same applies for any function which may produce discontinuity in gradient.
Gotcha. I have nil training in calculus; presumably
atan2(sin(x),cos(x)) has a discontinuous gradient?
At n*pi, the derivative is undefined because the function is discontinuous.