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

 
 

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

Submitted by:  Stephen <sh986>
Submitted on:  Wed 06 Dec 2017 05:14:23 PM UTC  
 
Category: Octave Forge PackageSeverity: 1 - Wish
Priority: 1 - LaterItem Group: Matlab Compatibility
Status: PostponedAssigned to: None
Originator Name: StephenOpen/Closed: Open
Release: otherOperating System: Any

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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>
Project Administrator
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>
Project Administrator
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 7 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Wed 21 Mar 2018 08:40:06 AM UTCmtmillerSeverity3 - 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
    Thu 15 Feb 2018 09:28:48 PM UTCmtmillerPriority5 - 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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