http://dec64.org/

I recently discovered this while watching a presentation by Doug Crockford on YouTube.

I know that Dlang is not in the category of languages that this new numeric representation is aimed at, but Dlang might well be used to implement a VM or compiler for one that is.

I think it is ripe for implementation along the same lines as half floats.

The reference implementation is on github (linked from the above) and is marked as public domain but porting the assembler (or rather the macros) non-trivial with my skill-set.

Anyone else convinced or opposed?

Anyone with more assembler-foo willing to lend a hand to the porting effort?

A...

On Saturday, 12 April 2014 at 21:48:15 UTC, Alix Pexton wrote:
> http://dec64.org/
>
> I recently discovered this while watching a presentation by Doug Crockford on YouTube.
>
> I know that Dlang is not in the category of languages that this new numeric representation is aimed at, but Dlang might well be used to implement a VM or compiler for one that is.
>
> I think it is ripe for implementation along the same lines as half floats.
>
> The reference implementation is on github (linked from the above) and is marked as public domain but porting the assembler (or rather the macros) non-trivial with my skill-set.
>
> Anyone else convinced or opposed?
>
> Anyone with more assembler-foo willing to lend a hand to the porting effort?
>
> A...

I don't quite see the point in this, when there is already a standard for floating point decimals http://en.wikipedia.org/wiki/Decimal64_floating-point_format
I really should take a deeper look at this, it might be more interesting that I am expecting.

On 13/04/2014 4:29 PM, Francesco Cattoglio wrote:

> I don't quite see the point in this, when there is already a standard
> for floating point decimals
> http://en.wikipedia.org/wiki/Decimal64_floating-point_format
> I really should take a deeper look at this, it might be more interesting
> that I am expecting.

The talk I watched only touched on the motivation for a new format very briefly, but the gist was that the existing offerings were too computationally expensive to emulate in software and hardware support is not forthcoming. My understanding is that this format is designed around what can be done efficiently with the instructions that are available in hardware today.

A...

On Sunday, 13 April 2014 at 18:42:43 UTC, Alix Pexton wrote:
> The talk I watched only touched on the motivation for a new format very briefly, but the gist was that the existing offerings were too computationally expensive to emulate in software and hardware support is not forthcoming. My understanding is that this format is designed around what can be done efficiently with the instructions that are available in hardware today.
>
> A...

This would make sense, at least partially, if hardware supporting the ieee was non-existant, but apparently hardware support for the decimal64 standard is already here!

Being a numerical analyst I can say I'm extremely interested when someone comes up with new interesting ideas, but as far as I can tell we still need to go down a long road before finding something better than good old floats. And I really think that one should stick to the standards, as long as the standard is good enough.

On a side note, I think that support for decimal64 might be something nice to have in the D language, because apparently that one is the most used floating point type in the economic sectors.

On 14/04/2014 10:44 AM, Francesco Cattoglio wrote:

> This would make sense, at least partially, if hardware supporting the
> ieee was non-existant, but apparently hardware support for the decimal64
> standard is already here!
>
> Being a numerical analyst I can say I'm extremely interested when
> someone comes up with new interesting ideas, but as far as I can tell we
> still need to go down a long road before finding something better than
> good old floats. And I really think that one should stick to the
> standards, as long as the standard is good enough.
>
> On a side note, I think that support for decimal64 might be something
> nice to have in the D language, because apparently that one is the most
> used floating point type in the economic sectors.

I did a little research, you are right, IBM has implemented the IEEE decimal floats in their Power6 and z9 chips (since 2007), and Sparc64 chips have it too (since 2012). But the amount of silicon required to create these decimal FPUs is significantly greater than for binary FPUs (as the format is essentially a dense form of BCD) and this makes it very unlikely that they will ever make their way into desktop or mobile processors.

The Dec64 decimal float is not a form of BCD, which is part of the reason why it can be emulated in software in a significantly more efficient way than the IEEE standard. While no hardware design exists, this would suggest that it would require less silicon, giving a greater chance that it will get into non-mainframe hardware.

A while ago there was a proposal for a new decimal float format to be included in ECMAScript 4 but the resources for that proposal seem to have been purged ()I've only found a few broken links. But as Doug Crockford (who at least wrote the dec64 reference implementation if not conceived the whole design) is on the TC39 committee that works on the standards for ECMAScript, I assume that it is related to that proposal and might even become a part of ECMAscript standard in the future.

Doug is a competent and respected programmer and speaker (among other things, he "discovered" JSON), and I believe that he would not have begun this project if there were not a compelling reason to do so. I hope that I am not misrepresenting him any way.

I will endeavour to port the reference implementation solo as it will undoubtedly be educational, and also to find more evidence that the effort is worth my time! I'll gladly share both.

A...

I contacted Doug to ask if he had any additional resources that I could use to make my argument for DEC64. I only got a brief reply (happy to get any reply from someone so busy) to the effect that everything he has to say on the matter is in the motivation segment of his web site for the proposal [1].

The most salient part is the last 2 sentences...

>	A later revision of IEEE 754 attempted to remedy this, but the
>	formats it recommended were so inefficient that it has not
>	found much acceptance. DEC64 is a better alternative.

I encourage anyone who is dismissive of the adoption of DEC64 or who would prefer to see the IEEE decimal floats implemented to take the time to read the full article. I also recommend the presentation that alerted me to DEC64 either in full (46:10) [2] or at least just the segment about numbers [3].

A...

[1]	http://dec64.org
[2]	https://www.youtube.com/watch?v=3WgVHE5Augc
[3] https://www.youtube.com/watch?feature=player_detailpage&v=3WgVHE5Augc#t=818

On Tuesday, 15 April 2014 at 07:12:41 UTC, Alix Pexton wrote:
> I contacted Doug to ask if he had any additional resources that I could use to make my argument for DEC64. I only got a brief reply (happy to get any reply from someone so busy) to the effect that everything he has to say on the matter is in the motivation segment of his web site for the proposal [1].
>
> The most salient part is the last 2 sentences...
>
> >	A later revision of IEEE 754 attempted to remedy this, but the
> >	formats it recommended were so inefficient that it has not
> >	found much acceptance. DEC64 is a better alternative.
>
> I encourage anyone who is dismissive of the adoption of DEC64 or who would prefer to see the IEEE decimal floats implemented to take the time to read the full article. I also recommend the presentation that alerted me to DEC64 either in full (46:10) [2] or at least just the segment about numbers [3].
>
> A...
>
> [1]	http://dec64.org
> [2]	https://www.youtube.com/watch?v=3WgVHE5Augc
> [3] https://www.youtube.com/watch?feature=player_detailpage&v=3WgVHE5Augc#t=818

I believe one form of decimal64 was intended for inclusion in D since at least 2009, according to this article: http://dlang.org/d-floating-point.html

This is an old thread but does any one know if any decimal types were ever implemented?

On 31/03/2015 7:22 PM, Gary Willoughby wrote:
> This is an old thread but does any one know if any decimal types were
> ever implemented?

I set off trying to implement DEC64 based on the halffloat module, but never got very far.

My main problem is that the assembler in the reference implementation renames all the registers, and as a result I really struggle to follow it ><

A...