On Nov 19, 2011, at 5:46 PM, Carnë Draug wrote: > On 19 November 2011 23:58, Jerry <lancebo...@qwest.net> wrote: >> Hi All, >> >> The function zp2sos in Signals always returns 1.0 for the gain of the second >> order sections. This isn't very useful. I believe it should return the gain >> factor to make the cascade of second order sections equal to the input >> filter which is in the form [zeros poles gain]. Indeed, this is the behavior >> described for the Matlab version at >> http://www.mathworks.com/help/toolbox/signal/ref/zp2sos.html. >> >> An example that shows the problem is simply to convert a second order filter >> in z-p-g form to a single second order section: >> >> octave-3.4.0:1> [b,a] = butter(2, 0.2) >> b = >> >> 0.067455 0.134911 0.067455 >> >> a = >> >> 1.00000 -1.14298 0.41280 >> >> octave-3.4.0:2> [z, p, g] = butter(2, 0.2) >> z = >> >> -1 -1 >> >> p = >> >> 0.57149 + 0.29360i 0.57149 - 0.29360i >> >> g = 0.067455 >> octave-3.4.0:3> [sos, sos_g] = zp2sos(z', p') >> sos = >> e >> 1.00000 2.00000 1.00000 1.00000 -1.14298 0.41280 >> >> sos_g = 1 >>>>> Should be 0.067455 <<<<<< >> >> >> The filter from the first input line should be the same as from the last >> input line but it differs in the gain factor. This is easy to fix but as it >> is the user has to do it. >> >> On two related matters, the Octave documentation for zp2sos, >> http://octave.sourceforge.net/signal/function/zp2sos.html, states that the >> arguments to zp2sos should be column vectors but using either column or row >> vectors results in the same answer. >> >> Also, on the same doc page, a quantity called Bscale is mentioned, but only >> once; it does not reference anything on the page. This should also be fixed. >> It probably refers to g but g is incorrect as noted above. >> >> I suppose the functions mentioned in the "See also" should be checked for >> similar problems. >> >> Jerry > > > Hi Jerry, > > do you think you can submit a patch to fix these (or maybe just some) > of the issues? > > Carnë
I could fix the problem if the source is Octave, but not if it is C. Jerry ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Octave-dev mailing list Octave-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/octave-dev
