Homothety
In mathematics, a homothety (or homothecy, or homogeneous dilation) is a transformation of an affine space determined by a point S called its center and a nonzero number k called its ratio, which sends point X to a point X′ by the rule, S X ′ → = k S X → {\displaystyle {\overrightarrow {SX'}}=k{\overrightarrow {SX}}} for a fixed number k ≠ 0 {\displaystyle k\neq 0} . Using position vectors: x ′ = s + k ( x − s ) .