Orthogonal MatrixMatrix의 row vector (and column vector)들이자기자신을 제외한 나머지 row vector (and column vector)들과 orthonormal인 square matrix.$$A^{-1}=A^\top \\ A^\top A = I \\ \mathbf{a}_i^\top \mathbf{a}_j = \mathbf{a}_i \cdot \mathbf{a}_j = 0, \quad \text{ where } i\ne j \\ \mathbf{a}_i^\top \mathbf{a}_j = \mathbf{a}_i \cdot \mathbf{a}_j = 0, \quad \text{ where } i = j$$엄격히 애기해서 orthogonal matrix는 $A^{-..