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Re: A question on Matlab compatibility

From: Ron Crummett
Subject: Re: A question on Matlab compatibility
Date: Sat, 16 Sep 2006 16:06:31 -0700
User-agent: Thunderbird (X11/20060909)

I'm not sure if I completely follow that. Looking at the code for both series and sysmult, I see that both were copyrighted in 1996 but that sysmult was again copyrighted in 1999. Whether sysmult was written before the Matlab control toolbox came out or after, it looks to me like there was a function called series that performed a cascade of systems. But really, that's beside the point.

All I am really trying to do is raise the issue of compatibility. If Matlab has a function that performs a series cascade of two systems and it is called 'series', and Octave has one that does the same thing, also called 'series', but it is preferred that you use this other one called 'sysmult' instead...why not just call it 'series' and maintain compatibility?

This is just one example that I have seen. There are others...for example, there are no filter conversion functions such as 'lp2lp' and 'lp2bp' - instead, there is just one, 'sftrans', which I have never been able to figure out and which has no Matlab counterpart. Again, I am sure that sftrans is a fine function and does its job well...but when I write code under Matlab and then try to run it on Octave later, I am expecting to be able to do so without having to do a lot of editing in my code. Some is necessary, I understand that. But when I want to do 'a' and am told that 'a' does not exist but 'b' does the same thing...why not just call it 'a' in the first place and save a lot of headache? If it is a simple matter of renaming the functions and resubmitting them, I'll do it. I can change a line of code or two, save it under a different filename and resubmit it, so long as I don't upset the powers that be who wrote these functions in the first place.


A. Scottedward Hodel wrote:
Because sysmult and the rest of the octave controls toolbox was written a year or more before MATLAB came out with object-oriented functionality in its controls toolbox. Of course, that was over 10 years ago. Bear in mind that MATLAB's controls functions make extensive use of MATLAB's user-defined objects, so it would be a significant effort to make octave's toolbox behave identically to MATLAB's.


A. Scottedward Hodel address@hidden

On Sep 15, 2006, at 7:11 PM, Ron Crummett wrote:

Hi -

I am currently taking a course in control theory and are assigned a
number of Matlab-based problems.  One problem discusses the use of the
'series' function, used to cascade two systems in series.  When I call
this function in Octave, I get a warning that the function is obsolete,
and to use 'sysmult' instead.  I am sure that 'sysmult' is a fine
function, but if the goal with Octave is Matlab compatibility (I've been
told more than once that it is), why create a similar function with a
different name?  Why not improve the existing series function and keep
the name?

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