Implement the "unum" representation in D ?

[jmh530 via Digitalmars-d]

On Wednesday, 16 September 2015 at 08:38:25 UTC, deadalnix wrote:
>
> Also, predictable size mean you can split your dataset and 
> process it in parallel, which is impossible if sizes are random.

I don't recall how he would deal with something similar to cache 
misses when you have to promote or demote a unum. However, my 
recollection of the book is that there was quite a bit of focus 
on a unum representation that has the same size as a double. If 
you only did the computations with this format, I would expect 
the sizes would be more-or-less fixed. Promotion would be pretty 
rare, but still possible, I would think.

Compared to calculations with doubles there might not be a strong 
case for energy efficiency (but I don't really know for sure). My 
understanding was that the benefit for energy efficiency is only 
when you use a smaller sized unum instead of a float. I don't 
recall how he would resolve your point about cache misses.

Anyway, while I can see a benefit from using unum numbers 
(accuracy, avoiding overflow, etc.) rather than floating point 
numbers, I think that performance or energy efficiency would have 
to be within range of floating point numbers for it to have any 
meaningful adoption.