freq frequency response [x]=freq(A,B,C [,D],f) [x]=freq(NUM,DEN,f) A, B, C, D real matrices of respective dimensions nxn, nxp, mxn, mxp. NUM,DEN polynomial matrices of dimension mxp x real or complex matrix x=freq(A,B,C [,D],f) returns a real or complex mxp*t matrix such that: x(:,k*p:(k+1)*p)= C*inv(f(k)*eye()-A)*B + D. Thus, for f taking values along the imaginary axis or on the unit circle x is the continuous or discrete time frequency response of (A,B,C,D). x=freq(NUM,DEN,f) returns a real or complex matrix x such that columns k*(p-1)+1 to k*p of x contain the matrix NUM(f(k))./DEN(f(k)) repfreq horner