The value must be [] or a Ny-by-Ny-by-Nf 3D numeric array, where Ny = number of outputs and Nf = number of frequen

[fyousefi]

The value must be [] or a Ny-by-Ny-by-Nf 3D numeric array, where Ny = number of outputs and Nf = number of frequency points. You can use a vector of length Nf for single output systems (Ny=1).