“…For both and -width defined by (11) can be computed exactly [33], where is the set of trigonometric polynomials of degree no larger than , and is any -dimensional subspace of . The model set has been used extensively for identification in [1], [3], [4], [18], [20], [21], [26], [28], [31], [32], and the set is recently investigated in [12]. Finally, we would like to mention that if one aims at identification of normalized left coprime factors of , the assumption , the number of inputs is larger than or equal to the number of outputs, needs to be imposed for loopshaping purposes.…”