andWkNfork=0...N−1arecalledtheNth roots of unity. They’re called this because, incomplex arithmetic,(WkN)N=1 for allk. They’re vertices of a regular polygon inscribedin the unit circle of the complex plane, with one vertex at (1,0). Below are roots of unityforN=2,N=4, andN=8, graphed in the complex plane.