By left-multiplication with an appropriate invertible matrix "L", it can be achieved that row "t" of the matrix product is the sum of σ times the original row "t" and τ times the original row "k", that row "k" of the product is another linear combination of those original rows, and that all other rows are unchanged. Explicitly, if σ and τ satisfy the above equation, then for formula_60 and formula_61 (which divisions are possible by the definition of β) one has