1. Symmetric, Skew-symmetric and Orthogonal matrices Def. Symmetric, Skew-symmetric and Orthogonal matrices A real square matrix $A$ = [$a_jk$] is called symmetric : $A^T$ = $A$ skew-symmetric : $A^T$ = -$A$ orthogonal : $A^T$ = $A^{-1}$ → $AA^T$ = $I$ cf) skew-symmetric : 대각선 성분들이 모두 0인 특성을 가짐 cf) 모든 matrix 는 R + S 로 나타낼 수 있다. R : symmetric matrix → $1/2$($A$ + $A^T$) S : skew-symmetric matrix ..
