Robuta

https://www.wolfram.com/mathematica/new-in-8/new-and-improved-core-algorithms/fast-null-space-computation-for-integer-matrices.html Fast Null Space Computation for Integer Matrices: New in Mathematica 8 null space integer matrices fast computation https://easychair.org/publications/preprint/dwFQ 2 x 2 Integer Matrices: Composition of Binary Quadratic Forms 2 x integer matrices composition binary quadratic