User`s guide

evalfr
11-72
11evalfr
Purpose Evaluate frequency response at a single (complex) frequency
Syntax frsp = evalfr(sys,f)
Description frsp = evalfr(sys,f) evaluates the transfer function of the TF, SS, or ZPK
model
sys at the complex number f. For state-space m odels with data
,theresultis
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.
Example To evaluate the discrete-time t ransfer function
at , type
H = tf([1 –1],[1 1 1],–1)
z = 1+j
evalfr(H,z)
ans =
2.3077e–01 + 1.5385e–01i
Limitations The response is not finite when f is a pole of sys.
See Also bode Bode frequency response
freqresp Frequency response o ver a set of frequencies
sigma Singular value respo nse
ABCD
,,,()
Hf() DCfIA–()
1
–
B+=
Hz()
z 1
–
z
2
z 1++
------------------------=
z 1 j
+=