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Frequency response of rational function object


[resp,outfreq] = freqresp(h,infreq)


[resp,outfreq] = freqresp(h,infreq) computes the frequency response, resp, of the rational function object, h, at the frequencies specified by freq.

The input h is the handle of a rational function object returned by rationalfit, and infreq is a vector of positive frequencies, in Hz, over which the frequency response is calculated.

The output argument outfreq is a vector that contains the same frequencies as the input frequency vector, in order of increasing frequency. The frequency response, resp, is a vector of frequency response values corresponding to these frequencies. It is computed using the analytical form of the rational function


where A, C, D, and Delay are properties of the rational function object, h.


collapse all

Compute the frequency response of data stored in the file,|passive.s2p| by reading it into an rfdata object, fitting a rational function object to the data, and using the freqresp method to compute the frequency response of the object



orig_data = with properties:

            Freq: [202x1 double]
    S_Parameters: [2x2x202 double]
      GroupDelay: [202x1 double]
              NF: [202x1 double]
            OIP3: [202x1 double]
              Z0: 50.0000 + 0.0000i
              ZS: 50.0000 + 0.0000i
              ZL: 50.0000 + 0.0000i
        IntpType: 'Linear'
            Name: 'Data object'

fit_data = 

   rfmodel.rational with properties:

        A: [6x1 double]
        C: [6x1 double]
        D: 0
    Delay: 0
     Name: 'Rational Function'

Introduced in R2006b

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