[Octave-bug-tracker] [bug #35730] freqz returns incorrectly scaled magnitude response

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?35730>

                 Summary: freqz returns incorrectly scaled magnitude response
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Tue 06 Mar 2012 09:34:30 AM UTC
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Jerry B
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.4.0
        Operating System: Mac OS

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Details:

If h is an FIR impulse response, then
freqz(h);
performs as advertised. However, 
freqz(h, N);
where N is any number including the default 512 returns incorrect magnitude
results. The incorrect result is wrong by a scale factor of 1/N, so that dB
plots are low by 20.0 * log10(N). If instead
freqz(h * N, N);
is used, the results are as would be expected if freqz were not broken.




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