Implement the "unum" representation in D ?

jmh530 via Digitalmars-d digitalmars-d at puremagic.com
Wed Feb 17 08:35:41 PST 2016


On Wednesday, 17 February 2016 at 08:11:21 UTC, Nick B wrote:
> Hi
>
> John Gustafson was in town (Wellington, NZ) for the Multicore 
> World Conference 2016 ( http://www.multicoreworld.com/) 
> conference. I caught up with him, tonight, and spoke to him for 
> about two hours. Here is a quick summary of what we discussed.  
> John has just redesigned Unums, to address the design issues in 
> version 1.0.  He presented his Powerpoint presentation to the 
> conference, with the details of Unums 2.0 (this is a tentative 
> name at present).  Its a improved design, but I will only brief 
> detail it:  "It  will have  more dynamic range with 16-bit 
> values than IEEE half-precision, but only by a small amount. 
> Still remarkable to be uniformly better in dynamic range and 
> precision, with support for inexact values and perfect 
> reciprocation. If a language supports just one unum data type, 
> John believes it should be the 16-bit one".  John has agreed to 
> provide a link to the Powerpoint presentation, in a couple of 
> weeks, and then later, a link to his new published paper on the 
> subject, when it is ready.  There will likely be a new book, 
> building on version 1.0, and, again, tentatively titled 'Unums 
> 2.0'. I also discussed with him, about integrating it with D. 
> At the present, there is a 'C' codebase under construction, but 
> this could be rewritten in D in the future.  D may require some 
> language changes, and a new phobos library, to support this 
> advanced functionality. Of course Walter will have decide if he 
> wants this advanced numbering system as a part of D.
>

I would be interested in the Powerpoint when it becomes available.

As for getting it to work in D, I'm not sure how much language 
changes would be necessary. If they can get it to work in C, then 
surely it would work in D. After all, the book has an 
implementation in python (albeit this is not the latest and great 
version apparently).

Wrt phobos, I would just recommend that whatever unum library 
gets eventually written has a companion with the equivalent of 
the functions from std.math.


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