Simplify implementation of coeff-based products to fully exploit our reduxion mechanisms. If this results in performance regressions, then we should optimize reduxion rather than somehow duplicate the code.
Simplify implementation of coeff-based products to fully exploit our reduxion mechanisms.
If this results in performance regressions, then we should optimize reduxion rather than
somehow duplicate the code.

madlib/eigen,madlib/eigen,madlib/eigen,madlib/eigen