Re: Triple parity and beyond

Hi,

First, create a 3 by 6 cauchy matrix, using x_i = 2^-i, and y_i = 0 for i=0, and y_i = 2^i for other i.
In this case:   x = { 1, 142, 71, 173, 216, 108 }  y = { 0, 2, 4).  The cauchy matrix is:

  1   2   4   8  16  32
244  83  78 183 118  47
167  39 213  59 153  82

Divide row 2 by 244 and row 3 by 167.  Then extend it with a row of ones on top and it's still MDS,
and  that's the code for m=4, with RAID-6 as a subset.  Very nice!

You got it Jim!

Thanks,
Andrea