Some special types of matrix identity matrix (or unit matrix):a diagonal matrix with all its diagonal elements equal to 1. 命电有这女子 Matrix Theory Matrices -5/14Some special types of matrix ▸ identity matrix (or unit matrix): a diagonal matrix with all its diagonal elements equal to 1. The following are identity matrices: ⎛ ⎜ ⎝ 1 0 0 0 1 0 0 0 1 ⎞ ⎟ ⎠ ( 1 0 0 1 ) ⎛ ⎜ ⎜ ⎜ ⎝ 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 ⎞ ⎟ ⎟ ⎟ ⎠ Notes: 1. The symbol I is usually reserved for labelling identity matrices. 2. The columns of the identity matrix are also called canonical vectors ei. 3. Use a subscript to indicate the size of the particular identity matrix we are discussing. So we might write I3 = ⎛ ⎜ ⎝ 1 0 0 0 1 0 0 0 1 ⎞ ⎟ ⎠ I2 = ( 1 0 0 1 ) I4 = ⎛ ⎜ ⎜ ⎜ ⎝ 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 ⎞ ⎟ ⎟ ⎟ ⎠ Matrix Theory Matrices - 5/14