Cartesian coordinates are a fundamental concept in mathematics and are central to computer graphics. Such rectangular coordinates are just offsets relative to some origin. Other coordinate systems also exist such as polar, spherical and cylindrical coordinates, and they, too, require an origin. Barycentric coordinates, on the other hand, locate points relative to existing points, rather than to an origin and are known as local coordinates. The German mathematician August Möbius (1790–1868) is credited with their discovery.