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Mathematics-Online course: Linear Algebra - Matrices - Special Matrices

Orthogonal and Unitary Matrices


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A complex $ n\times n$-matrix $ A$ is called unitary if

$\displaystyle A^{-1} = {\overline{A}}^{\operatorname t}=A^\ast\,
,
$

that is, if the columns of $ A$ form a orthonormal basis of $ \mathbb{C}^n$. For real matrices the complex conjugation can be omitted (as with the scalar product). A unitary matrix with real entries is called orthogonal matrix.

Orthogonal (unitary) matrices form a subgroup of $ \operatorname{GL}(n, \mathbb{R})$ ( $ \operatorname{GL}(n, \mathbb{C})$).


  automatically generated 4/21/2005