reference implementation of BLAS

[Tim Prince]

Steve Kargl wrote:

> 
> Are you using -ffast-math?  DON'T!
> 

There are a few potentially useful optimizations included in 
-ffast-math, such as optimization of sum reduction by parallel addition, 
abrupt underflow, and optimization of repeated division by an invariant.
Apparently, there are also shortcuts for multiply by 1. and 0. They are 
outweighed by other performance losses, as well as the bugs you no doubt 
encounter.  Generally, in addition, people tend to set it up to invoke 
some broken shortcuts in math libraries, or mathinline.h.  If you could 
find out how to invoke the individual optimizations which have a chance 
of success, that might be interesting.