Re: [OctDev] new release?

[David B. <Dav...@mo...>]

Quentin,

The reason for the reversal is a stupidity in matlab. I can't remember
the details offhand but I believe hammgen and cyclgen return the matrices
in reverse order. Similarly the polynomials with cyclpoly are reversed...
I tried to keep the functions consistent with each other, so that they
might be used interchangably.

Regards
David

According to Quentin Spencer <qsp...@ie...> (on 07/06/04):
> I just returned from vacation and noticed that CVS contained several 
> updates to the files in question in my previous mail below. I'm happy to 
> report that cyclgen appears to work properly for the inputs that I 
> tested. I also tested cyclpoly and discovered that when compared to the 
> ouput of the same function in Matlab, the results are the same but 
> appear in reverse order, i.e. fliplr(cyclgen(255,247)) is equivalent to 
> cyclgen(255,247) in Matlab. Thank you for all the work you have done in 
> fixing these functions.
> 
> -Quentin
> 
> 
> 
> Quentin Spencer wrote:
> 
> >OK, I tested your changes to the coding stuff and this is what I found:
> >
> >bchpoly appears to give correct results for the cases I tested
> >cyclgen(255,bchpoly(255,247)) gives the correct result
> >cyclgen(255,bchpoly(255,239)) gives a matrix that is correct in the
> >first 8x8 submatrix, and zeros everywhere else !?
> >cyclpoly gives a vector containing all zeros for every input I tried.
> >
> >Well, I guess there's at least some progress since one case worked. I'm
> >sorry the news isn't better.
> >
> >-Quentin
> >
> >
> >David Bateman wrote:
> >
> >>According to Quentin Spencer <qsp...@ie...> (on 06/16/04):
> >>
> >>>David,
> >>>
> >>>Thanks. The updates fixed hammgen. However, now I've found another 
> >>>bug. I don't know if it was there all along or newly introduced. The 
> >>>following command should produce the 16x255 parity check matrix for 
> >>>a BCH 2-error correcting code:
> >>>cyclgen(255,bchpoly(255,239))
> >>>
> >>>The result instead is:
> >>>error: cyclgen: generator polynomial does not produce cyclic code
> >>>
> >>>I verified the resulting polynomial against MATLAB and they matched.
> >>
> >>Ok, I'm a bit draft. The test I added checks if the polynomial is 
> >>primitive
> >>rather than just irreducible. I'd previously tried to adapt this test in
> >>the older code, but failed.
> >>
> >>So I went back to the basic implementation of dividing x^n-1 by the
> >>polynomial and checking that there was no remainder. It appears to
> >>work correctly for you test case now. Though maybe you want to give
> >>it a bit more testing.. Changes checked into the CVS
> >>
> >>Regards
> >>David
> >

-- 
David Bateman                                Dav...@mo...
Motorola CRM                                 +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 1 69 35 77 01 (Fax) 
91193 Gif-Sur-Yvette FRANCE

The information contained in this communication has been classified as: 

[x] General Business Information 
[ ] Motorola Internal Use Only 
[ ] Motorola Confidential Proprietary