Square Functions

The square periodic functions are derived from the geometry of the curve (3.1) | y | + | x | = 1. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429446238/d61a7316-5f65-4e0a-956e-ef5c7afc82a1/content/eq276.tif"/>