Specifications

freqresp
16-87
Algorithm For transfer functions or zero-pole-gain models, freqresp evaluates the
numerator(s) and denominator(s) at the specified frequency points. For
continuous-time state-space models , the frequency response is
For efficiency, is reduced to upper Hessenberg form and the linear
equation is solved at each frequency point, taking advantage
oftheHessenbergstructure.The reductiontoHessenbergformprovides a good
compromise between efficiency and reliability. See [1] for more details on this
technique.
Diagnostics If the system has a pole on the axis (or unit circle in the discrete-time case)
and
w happens to contain this frequency point, the gain is infinite, is
singular, and
freqresp produces the following warning message.
Singularity in freq. response due to jw-axis or unit circle pole.
See Also evalfr Response at single complex frequency
bode Bode plot
nyquist Nyquist plot
nichols Nichols plot
sigma Singular value plot
ltiview LTIsystemviewer
interp Interpolate FRD model between frequency points
References [1] Laub, A.J., “Efficient Multivariable Frequency Response Computations,”
IEEE Transactions on Automatic Control, AC-26 (1981), pp. 407-408.
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