> Eigen does this via expression templates; it essentially optimises the computation graph at compile time. That's wrong too. The right query execution plan ca

> Eigen does this via expression templates; it essentially optimises the computation graph at compile time. That's wrong too. The right query execution plan can depend heavily on the sizes and statistical distributions of the operands. Eigen doesn't have enough information at compile time to make good decisions in all cases. This kind of computation really calls for a JIT.