Two vectors and are said to be orthonormal
if they are both orthogonal
. A set of vectors which are pairwise orthonormal is called an orthonormal set
When referring to functions, usually the L²-norm is assumed unless otherwise stated, so that two functions and are orthonormal over the interval if
Unfortunately, the word normal
is sometimes used synonymously with orthogonal
See also: normalized vector, orthogonal, Lp space.