orthogonality

orthogonality, In mathematics, a property synonymous with perpendicularity when applied to vectors but applicable more generally to functions. Two elements of an inner product space are orthogonal when their inner product—for vectors, the dot product (see vector operations); for functions, the definite integral of their product—is zero. A set of orthogonal vectors or functions can serve as the basis of an inner product space, meaning that any element of the space can be formed from a linear combination (see linear transformation) of the elements of such a set.