There is only one Hadamard equivalence class of 8 x 8 Hadamard
matrices. We construct one matrix, and two of its designs.
> R := MatrixRing(Integers(), 8);
> H := R![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, -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,
> 1, -1, -1, 1, 1, -1, 1, -1];
> IsHadamard(H);
true
> DR := HadamardRowDesign(H, 3);
> DR: Maximal;
3-(8, 4, 1) Design with 14 blocks
Points: {@ 1, 2, 3, 4, 5, 6, 7, 8 @}
Blocks:
{1, 2, 5, 6},
{1, 2, 7, 8},
{1, 2, 3, 4},
{1, 4, 5, 7},
{1, 4, 6, 8},
{1, 3, 6, 7},
{1, 3, 5, 8},
{3, 4, 7, 8},
{3, 4, 5, 6},
{5, 6, 7, 8},
{2, 3, 6, 8},
{2, 3, 5, 7},
{2, 4, 5, 8},
{2, 4, 6, 7}
> HadamardColumnDesign(H, 8);
3-(8, 4, 1) Design with 14 blocks