[R] A slightly unorthodox matrix product.

[Berry, Charles]

> On Aug 4, 2018, at 12:59 PM, Jeff Newmiller <jdnewmil using dcn.davis.ca.us> wrote:
> 
...

> Slick work on the vectorizing, but for the future reference it was slightly buggy:
> 

Thanks for catching that!

Chuck