Path: utzoo!attcan!uunet!mcsun!ukc!tcdcs!swift.cs.tcd.ie!vax1.tcd.ie!rmclvrty
From: rmclvrty@vax1.tcd.ie
Newsgroups: comp.dsp
Subject: MATLAB laziness
Message-ID: <1990Nov30.164632.7336@vax1.tcd.ie>
Date: 30 Nov 90 16:46:32 GMT
Organization: Trinity College Dublin
Lines: 30


To whom it concerns,
			I write in connection with the MATLAB signal
processing package.  I have been using it for some time now, particularly
the functions in the signal processing toolbox.  Specifically, I use
version 3.5f VAX MATLAB.  I have incorporated my own PASCAL module into
this; this passes variable complex frequency responses to MATLAB.  I ultimately
need to realise these responses with real-time digital filters in full
audio (20kHz) bandwidth.  I have chosen IIR design methods and have set the
order to 20-over-20.  For programming and error propagation reasons I wish
to implement the filters in second order cascaded sections; common
practice.  This raises the issues of pole-zero pairing and cascade section
ordering.  There are indeed rules of thumb which may be applied which
minimise large response fluctuations between individual sections and which
order the sections to minimise noise power at the filter output.  
I have met with difficulty in doing this in a systematic way as
I have hundreds of coefficient sets to handle.  My version of MATLAB does
not have a cascading fuction-this surprises me as it is a widely practised
procedure.  Does MATLAB now feature a programmed solution to this problem?; 
i.e. the problem of optimally cascading 20 coefficients of a Z-plane digital
filter to 10 sections of order 2 and ordering those sections to minimise 
noise at the output.  If not, please refer me to literature or persons in
the know on this topic.
	Another small query: does MATLAB now facilitate labelling the axes
of mesh plots?- this has always been a nagging problem with my version.  
Thank you in advance for your attention.
        If anybody has any information that could aid me in my predicament and
cure this ailment please e-mail the 'aspirin' to maccabe@mee.tcd.ie , and not
to the above address.
                                         


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