The Unitary group reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Unitary group

In mathematics, the unitary group of degree n over the field F (which is either the field R of real numbers or the field C of complex numbers) is the group of n by n unitary matrices with entries from F, with the group operation that of matrix multiplication. This is a subgroup of the general linear group Gl(n,F).

If the field F is the field of real numbers then the unitary group coincides with the orthogonal group O(n,R). If F is the field of complex numbers one usually writes U(n) for the unitary group of degree n.

The unitary group U(n) is a real Lie group of dimension n². The Lie algebra of U(n) consists of complex n-by-n Skew-hermitian matrices, with the Lie bracket given by the commutator.

See also: Special unitary group

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