Unitary Matrix

Author

Eric W. Weisstein
April 22, 2003

This notebook downloaded from http://mathworld.wolfram.com/notebooks/LinearAlgebra/UnitaryMatrix.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/UnitaryMatrix.html.

©2005 Wolfram Research, Inc. except for portions noted otherwise

Code

UnitaryQ[m_List?MatrixQ] :=
    (Conjugate@Transpose@m.m ==IdentityMatrix@Length@m)

Example

a={{1/Sqrt[2],1/Sqrt[2],0},{-I/Sqrt[2],I/Sqrt[2],0},{0,0,I}};

UnitaryQ[a]

UnitaryQ[a/2]