CustomFloat

[Andrei Alexandrescu]

Paul D. Anderson wrote:
> Andrei Alexandrescu Wrote:
> 
>> I found myself in need for smaller and specialized floating point
>> types, where I configure the exact configuration (sign, mantissa,
>> exponent, bias). See http://en.wikipedia.org/wiki/Half_precision
>> for a half precision number slated for inclusion in IEEE 754r.
>> 
>> Would it be interesting to add a CustomFloat template to phobos?
>> I'm thinking along the lines of:
>> 
>> template CustomFloat!(bool sign, uint mantissa, uint exponent, uint
>> bias) { ... }
>> 
>> So half-precision numbers are:
>> 
>> alias CustomFloat!(true, 5, 10, 15) HalfFloat;
>> 
>> There are quite a few details to kink out but this is definitely
>> doable. Numbers like 24-bit floating point and even 8-bit floating
>> point would be easy to support too. For now CustomFloat would be
>> intended exclusively as a compact storage mechanism; only
>> conversion to the standard floating points would be implemented.
>> Later, maybe we can get to implement some operations natively at
>> least on machines that support them in hardware. I wanted to gauge
>> interest in the topic.
>> 
>> 
>> Andrei
> 
> I've done some work on a set of decimal floating point numbers
> consistent with the new 754r decimal formats approved in June. Some
> of that work would be applicable here, I think.
> 
> It would probably make sense to add the decimal formats at the same
> time. Let me know if I can help.

Sounds interesting, and thanks for the offer. I'd be glad to add decimal 
types too, in case there's enough interest. I think monetary 
calculations can be helped, and what don't we do nowadays to help people 
involved in monetary calculations? :o)

Andrei