# Gram matrix

From Encyclopedia of Mathematics

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

then

where is the -matrix consisting of the columns . The symbol denotes the operation of matrix transposition, while the bar denotes complex conjugation of the variable. See also Gram determinant.

#### Comments

#### References

[a1] | H. Schwerdtfeger, "Introduction to linear algebra and the theory of matrices" , Noordhoff (1950) (Translated from German) |

**How to Cite This Entry:**

Gram matrix. L.P. Kuptsov (originator),

*Encyclopedia of Mathematics.*URL: http://www.encyclopediaofmath.org/index.php?title=Gram_matrix&oldid=19116

This text originally appeared in Encyclopedia of Mathematics - ISBN 1402006098