1.1 Special Form Matrices oDiagonal matrices and anti-diagonal matrices 、 = diag(d,d2,…,dn) D- Upper/lower triangular matrices R-t When all diagonal elements are equal to 1,call the above matrices unit upper/lower triangular matrices. 1 Special Matrices 2/601.1 Special Form Matrices Diagonal matrices and anti-diagonal matrices D =   d1 d2 . . . dn   = diag(d1, d2, · · · , dn) D¯ =   d1 d2 . . . dn   Upper/lower triangular matrices R =   ∗ ∗ · · · ∗ ∗ · · · ∗ . . . . . . ∗   L =   ∗ ∗ ∗ . . . . . . . . . ∗ ∗ ∗   When all diagonal elements are equal to 1, call the above matrices unit upper/lower triangular matrices. 1 Special Matrices 2 / 60