There's a 3rd option - keeping a modifications' log and applying them all destructively on just 1 temporary copy only when the result is needed. A = normal

There's a 3rd option - keeping a modifications' log and applying them all destructively on just 1 temporary copy only when the result is needed. A = normalized(X*b - M*N*k); //creates a pipeline A.calculate(); //calculates all the stages destructively on the new copy