On Apr 15, 8:45 am, Andrea Gobbi <[email protected]> wrote:
> Hi!
> I'm using sage for coding theory, and it sems to be great! I have a
> linear code like this:
> MS = MatrixSpace(GF(3),10,27)
> G  = MS([
> [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],
> [1,2,0,0,0,0,1,1,2,2,0,0,0,0,1,1,2,2,1,1,1,1,2,2,2,2,0],
> [0,0,1,2,0,0,1,2,1,2,1,1,2,2,0,0,0,0,1,1,2,2,1,1,2,2,0],
> [0,0,0,0,1,2,0,0,0,0,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,0],
> [0,0,0,0,0,0,1,2,2,1,0,0,0,0,0,0,0,0,1,1,2,2,2,2,1,1,0],
> [0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,2,2,1,1,2,1,2,2,1,2,1,0],
> [0,0,0,0,0,0,0,0,0,0,1,2,2,1,0,0,0,0,1,2,2,1,1,2,2,1,0],
> [1,1,0,0,0,0,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,0],
> [0,0,1,1,0,0,1,1,1,1,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1,0],
> [0,0,0,0,1,1,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0]]);
> C  = LinearCode(G);
> C.dimension();
> C.length();
> C.minimum_distance();
> C.weight_distribution();
> And I want use the minimum distance (in this case 9) for correct a
> vector with 8 erasures. There are some tools in sage to do this? I try

If the minimum distance is 9, then, I think, only vectors with 4
erasures or less can be decoded correctly. Consider, for example, the
last row with 5 zeros replaced with ones - if 5 erasures were allowed,
then erasing them, we would get the last row, but erasing 4 remaining
zeros in it instead, we would get the first row - so it couldn't be
uniquely decoded.

Alec

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