Re: Triple parity and beyond

Hi Piergiorgio,

Checking better I found that for PAR3 it was also evaluated a Cauchy
matrix, but they preferred to use a RS with FFT in GF(2^16 +1).

http://sourceforge.net/mailarchive/forum.php?forum_name=parchive-devel&max_rows=25&style=nested&viewmonth=201006

Note that using a Cauchy matrix for a MDS is something well known.
What I did is just to adapt a Cauchy matrix to be compatible with the
present Linux kernel implementation. I think it has a value only for
Linux or compatible implementations.

Ciao,
Andrea

On Sat, Nov 23, 2013 at 11:10 PM, Piergiorgio Sartor
[off-list ref] wrote:

Hi Andrea,

On Sat, Nov 23, 2013 at 08:55:08AM +0100, Andrea Mazzoleni wrote:

quoted

Hi Piergiorgio,

quoted

How about par2? How does this work?

I checked the matrix they use, and sometimes it contains some singular
square submatrix.
It seems that in GF(2^16) these cases are just less common. Maybe they
were just unnoticed.

Anyway, this seems to be an already known problem for PAR2, with an
hypothetical PAR3 fixing it:

http://sourceforge.net/p/parchive/discussion/96282/thread/d3c6597b/

you did a pretty damn good research work!

Maybe you should consider to contact them too.
I'm not sure if your approach can be extended
to GF(2^16), I guess yes, in that case they
might be interested too.

bye,

--

piergiorgio