The Discrete Transfer Fcn block implements the z-transform transfer function:
H(z)=num(z)/den(z)=...
where m+1 and n+1 are the number of numerator and denominator coefficients, respectively. num and den contain the coefficients of the numerator and denominator in descending powers of z. num can be a vector or matrix, den must be a vector, and you specify both as parameters on the block dialog box. The order of the denominator must be greater than or equal to the order of the numerator.