An $n\times n$ real matrix $A$ is orthogonal if its column vectors (equivalently, its row vectors) are orthonormal. That is, the product of $A$ with its transpose $A^T$ is equal to the identity matrix $I_n$: \(AA^T = A^TA = I_n\) Equivalently, the transpose of an orthogonal matrix $A$ is equal to its inverse: $A^T = A^{-1}$.
Wikidata ID: Q333871