The square matrix
consisting of pairwise scalar products of elements (vectors) of a (pre-)Hilbert space. All Gram matrices are non-negative definite. The matrix is positive definite if are linearly independent. The converse is also true: Any non-negative (positive) definite -matrix is a Gram matrix (with linearly independent defining vectors).
If are -dimensional vectors (columns) of an -dimensional Euclidean (Hermitian) space with the ordinary scalar product
|[a1]||H. Schwerdtfeger, "Introduction to linear algebra and the theory of matrices" , Noordhoff (1950) (Translated from German)|
Gram matrix. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Gram_matrix&oldid=35177