a method to find the nearest multiple of 2pi

Question

I need to make an efficient function that matches this footprint:

public static double NearestAngle(this double currentAngle, double targetAngle);

where the return value is targetAngle +/- n*2pi. The return value should minimize the absolute difference between itself and currentAngle. How can I do this efficiently in C#? I want to avoid loops as the inputs can be many circles apart.

Answer 1

return targetAngle + Math.Round((currentAngle - targetAngle)/(2*Math.Pi))*2*Math.Pi;