Reed-Solomon: inverting a matrix of GF elements

How does one invert a matrix of GF elements? 
  
Specifically, I would like to see the case of a 3x3 matrix.
Thank you for any information.

On Nov 8, 7:58&#4294967295;pm, "lindasel" <lselt...@alumni.caltech.edu> wrote:
> How does one invert a matrix of GF elements?
>
> Specifically, I would like to see the case of a 3x3 matrix.
> Thank you for any information.

Pretty much the same way as with any other matrix. You just need to do
the intermediate arithmetic in GF(p^n) instead of in R or C.

 - Kenn

More specifically, one step in inverting a conventional matrix is to find
the cofactors from the transpose.  In a 3x3 matrix, for example, there is a
sign change for the cofactors of the second row.  Is there any operation
that has to be done for the second row of the cofactors matrix when a GF
matrix is inverted, or is everything computed with XORs with nothing
different in the second row?

I got the inverse to work.  It wasn't necessary to change anything in the
second row.