Dear GAP Forum,

Stas Bulygin wrote:
>
> Dear GAP-Forum,
> I got the following problem in package GUAVA 1.4:
> gap> GeneratorMat(HammingCode(3,GF(2)));
> [ <an immutable GF2 vector of length 7>, <an immutable GF2 vector of length
> 7>
> , <an immutable GF2 vector of length 7>,
> <an immutable GF2 vector of length 7> ]
>
> What should I do to obtain the generator matrix in the explicit form, or how
> should I read this output?

The following should work.

gap> RequirePackage("guava");
gap> G:=GeneratorMat(HammingCode(3,GF(2)));
[ <an immutable GF2 vector of length 7>, <an immutable GF2 vector of
length 7>
    , <an immutable GF2 vector of length 7>, 
  <an immutable GF2 vector of length 7> ]
gap> GM:=[];                        
[  ]
gap> for j in [1..4] do
> GM[j]:=List([1..7],i->G[j][i]);
> od;
gap> GM;
[ [ Z(2)^0, Z(2)^0, Z(2)^0, 0*Z(2), 0*Z(2), 0*Z(2), 0*Z(2) ], 
  [ Z(2)^0, 0*Z(2), 0*Z(2), Z(2)^0, Z(2)^0, 0*Z(2), 0*Z(2) ], 
  [ 0*Z(2), Z(2)^0, 0*Z(2), Z(2)^0, 0*Z(2), Z(2)^0, 0*Z(2) ], 
  [ Z(2)^0, Z(2)^0, 0*Z(2), Z(2)^0, 0*Z(2), 0*Z(2), Z(2)^0 ] ]

Hope that helps. - David

--
Prof David Joyner, Mathematics Department
U. S. Naval Academy, Annapolis, MD 21402
phone: (410) 293-6738