Wrapped distribution
In probability theory and directional statistics, a wrapped probability distribution is a continuous probability distribution that describes data points that lie on a unit n-sphere. In one dimension, a wrapped distribution will consist of points on the unit circle. If φ is a random variate in the interval (-∞,∞;) with probability density function p(φ), then z = e will be a circular variable distributed according to the wrapped distribution pzw(z) and θ=arg(z) will be an angular variable in the interval (-π,π ] distributed according to the wrapped distribution pw(θ).