Evaluate frequency response at given frequency
frsp = evalfr(sys,f)
H(f) = D + C (fI – A)–1B
evalfr is a simplified version of freqresp meant for quick evaluation of the response at a single point. Use freqresp to compute the frequency response over a set of frequencies.
To evaluate the discrete-time transfer function
at z = 1 + j, type
H = tf([1 -1],[1 1 1],-1); z = 1+j; evalfr(H,z)
to get the result:
ans = 2.3077e-01 + 1.5385e-01i
To evaluate the frequency response of a continuous-time IDTF model at frequency w = 0.1 rad/s, type:
sys = idtf(1,[1 2 1]); w = 0.1; s = 1j*w; evalfr(sys, s)
The result is same as freqresp(sys, w).