An orthogonal-matrix is a square-matrix and its transpose is equal to its inverse.
(<=> (Orthogonal-Matrix ?M)
(And (Square-Matrix ?M)
(Same-Values ?M Transpose Matrix-Inverse)))
(Square-Matrix ?M)
(<=> (Orthogonal-Matrix ?M)
(And (Square-Matrix ?M)
(Same-Values ?M Transpose Matrix-Inverse)))