[      0,  I*pi/2, -I*pi/2,       0],
        [      0, -I*pi/2,  I*pi/2,       0],
        [-I*pi/2,       0,       0,  I*pi/2]])
        z+Logarithm is valid only for square matricesz[Logarithm is implemented only for matrices for which the Jordan normal form can be computedc