(1) -> A:=matrix [[0,-%i],[%i,0]]

        +0   - %i+
   (1)  |        |
        +%i   0  +
                                               Type: Matrix(Complex(Integer))
(2) -> A^4

        +1  0+
   (2)  |    |
        +0  1+
                                               Type: Matrix(Complex(Integer))
(3) -> A^(-1)

        +0   - %i+
   (3)  |        |
        +%i   0  +
                                     Type: Matrix(Fraction(Complex(Integer)))
(4) -> inverse A

        +0   - %i+
   (4)  |        |
        +%i   0  +
                          Type: Union(Matrix(Fraction(Complex(Integer))),...)