bugGNU Octave - Bugs: bug #52604, [octave forge] (signal) invfreqs,...

 
 

bug #52604: [octave forge] (signal) invfreqs, invfreqz iterative algorithm is not implemented

Submitter:  Stephen <sh986>
Submitted:  Wed 06 Dec 2017 05:14:23 PM UTC
   
 
Category:  Octave Package Severity:  1 - Wish
Priority:  1 - Later Item Group:  Matlab Compatibility
Status:  Postponed Assigned to:  None
Originator Name:  Stephen Open/Closed:  * Open
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
* Mandatory Fields

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Wed 21 Mar 2018 08:40:06 AM UTC, comment #3: 

I have added a warning message to the invfreqs and invfreqz functions when the iter or tol arguments are given. It should now be clear that the iterative algorithm is not yet implemented in these functions.

http://hg.code.sf.net/p/octave/signal/rev/20e85c76d212

Mike Miller <mtmiller>
Group Member
Thu 15 Feb 2018 09:28:48 PM UTC, comment #2: 

There is supposed to be a warning message printed in this function when the iteration parameter is given. The function should print

"no implementation for iter yet"

So this is a known missing feature of this function. Printing the warning again is easy, implementing the missing feature is a larger project.

Mike Miller <mtmiller>
Group Member
Wed 06 Dec 2017 05:41:43 PM UTC, comment #1: 

Also, invfreqz(h,w,3,3,wt,30) shown below doesn't return the same result as matlab (see https://edoras.sdsu.edu/doc/matlab/toolbox/signal/spectop9.html)


>> [b,a] = butter(4,0.4)

b =

   0.046583   0.186332   0.279497   0.186332   0.046583

a =

   1.000000  -0.782095   0.679979  -0.182676   0.030119

>> [h,w] = freqz(b,a,64);
>> [b4,a4] = invfreqz(h,w,4,4)

b4 =

   0.046583   0.186332   0.279497   0.186332   0.046583

a4 =

   1.000000  -0.782095   0.679979  -0.182676   0.030119

>> wt = ones(size(w));
>> [b30,a30] = invfreqz(h,w,3,3,wt,30)

b30 =

   0.046389   0.178546   0.244578   0.127586

a30 =

   1.00000  -0.95016   0.73823  -0.20056

Stephen <sh986>
Wed 06 Dec 2017 05:14:23 PM UTC, original submission:  

Matlab invfreqz(h,w,4,5,[],30) example doesn't give sample output as octave.

See https://www.mathworks.com/help/signal/ref/invfreqz.html

Stephen <sh986>

 

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    Follow 9 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-02-26 mtmiller Releaseother dev
    2019-02-26 mtmiller Carbon-CopyRemoved 80942 -
    2018-03-21 mtmiller Severity3 - Normal 1 - Wish
        Release4.2.1 other
        Summary[octave forge] (signal) invfreqz(..., iterations) is not implemented [octave forge] (signal) invfreqs, invfreqz iterative algorithm is not implemented
    2018-02-15 mtmiller Priority5 - Normal 1 - Later
        StatusNone Postponed
        Operating SystemMicrosoft Windows Any
        SummaryMatlab invfreqz(h,w,4,5,[],30) example doesn't give sample output as octave [octave forge] (signal) invfreqz(..., iterations) is not implemented

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