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January 28, 2013
Implementing Half Floats in D
http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674

Anyone care to do the reddit honors?
January 28, 2013
Re: Implementing Half Floats in D
On Monday, 28 January 2013 at 23:11:11 UTC, Walter Bright wrote:
> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
>
> Anyone care to do the reddit honors?

[quote]
  and crushed back down to 16 bytes for storage.
[/quote]

 Should be bits. Otherwise it looks really well done.
January 28, 2013
Re: Implementing Half Floats in D
On Mon, 28 Jan 2013 15:11:06 -0800, Walter Bright wrote:

> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
> 
> Anyone care to do the reddit honors?

Posted to /r/d_language, perhaps a x-post to /r/programming would be in 
order?

http://www.reddit.com/r/d_language/comments/17gkrk/
implementing_half_floats_in_d_dr_dobbs/
January 28, 2013
Re: Implementing Half Floats in D
On 1/28/13 6:40 PM, Justin Whear wrote:
> On Mon, 28 Jan 2013 15:11:06 -0800, Walter Bright wrote:
>
>> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
>>
>> Anyone care to do the reddit honors?
>
> Posted to /r/d_language, perhaps a x-post to /r/programming would be in
> order?
>
> http://www.reddit.com/r/d_language/comments/17gkrk/
> implementing_half_floats_in_d_dr_dobbs/

Not sure what's going on, I tried to submit and got "already submitted" 
and then got redirected to 
http://www.reddit.com/r/programming/comments/16ycws/implementing_half_floats_in_d/

Hoever, I can't find the post in http://www.reddit.com/r/programming/new/


Andrei
January 28, 2013
Re: Implementing Half Floats in D
On Mon, 28 Jan 2013 18:50:22 -0500, Andrei Alexandrescu wrote:

> On 1/28/13 6:40 PM, Justin Whear wrote:
>> On Mon, 28 Jan 2013 15:11:06 -0800, Walter Bright wrote:
>>
>>> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
>>>
>>> Anyone care to do the reddit honors?
>>
>> Posted to /r/d_language, perhaps a x-post to /r/programming would be in
>> order?
>>
>> http://www.reddit.com/r/d_language/comments/17gkrk/
>> implementing_half_floats_in_d_dr_dobbs/
> 
> Not sure what's going on, I tried to submit and got "already submitted"
> and then got redirected to
> http://www.reddit.com/r/programming/comments/16ycws/
implementing_half_floats_in_d/
> 
> Hoever, I can't find the post in
> http://www.reddit.com/r/programming/new/
> 
> 
> Andrei

Possibly this: http://code.reddit.com/wiki/help/
faq#Whyisntmysubmissioncommentshowingup

Walter is an admin; maybe he can check on it?
January 28, 2013
Re: Implementing Half Floats in D
On 1/28/2013 3:50 PM, Andrei Alexandrescu wrote:
> Not sure what's going on, I tried to submit and got "already submitted" and then
> got redirected to
> http://www.reddit.com/r/programming/comments/16ycws/implementing_half_floats_in_d/

8 days old, durn, it's sunsetted.
January 28, 2013
Re: Implementing Half Floats in D
On 1/28/2013 3:30 PM, Era Scarecrow wrote:
> On Monday, 28 January 2013 at 23:11:11 UTC, Walter Bright wrote:
>> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
>>
>> Anyone care to do the reddit honors?
>
> [quote]
>    and crushed back down to 16 bytes for storage.
> [/quote]
>
>   Should be bits. Otherwise it looks really well done.

thank you. Sorry that didn't get caught in review!
January 29, 2013
Re: Implementing Half Floats in D
Walter Bright:

> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674

From the article:

>Built-in types tend to run faster because the optimizer can take 
>advantage of mathematical identities,<

Generally in D we like the compiler to verify user-applied 
annotations like pure and const. For the compiler of a normal 
language today it's probably too much difficult to prove the 
theorems coming from those identities on user defined types. But 
if the compiler assumes the programmer to be right on this 
(because such types are usually defined in well reviewed 
libraries), then I think it's not too much hard to invent a small 
set of @annotations that attached to a user defined struct tell 
the compiler to allow some optimizations typical of integral 
numbers, floating point numbers, complex numbers, gaussian 
integers, quaternions, octonions and few others, according to 
them having associative, commutative, etc, properties, or not 
having them.

Bye,
bearophile
January 29, 2013
Re: Implementing Half Floats in D
On Tue, Jan 29, 2013 at 01:44:20AM +0100, bearophile wrote:
> Walter Bright:
> 
> >http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
> 
> From the article:
> 
> >Built-in types tend to run faster because the optimizer can take
> >advantage of mathematical identities,<
> 
> Generally in D we like the compiler to verify user-applied
> annotations like pure and const. For the compiler of a normal
> language today it's probably too much difficult to prove the
> theorems coming from those identities on user defined types. But if
> the compiler assumes the programmer to be right on this (because
> such types are usually defined in well reviewed libraries), then I
> think it's not too much hard to invent a small set of @annotations
> that attached to a user defined struct tell the compiler to allow
> some optimizations typical of integral numbers, floating point
> numbers, complex numbers, gaussian integers, quaternions, octonions
> and few others, according to them having associative, commutative,
> etc, properties, or not having them.
[...]

+1.  I've always wanted a language capable of user-specified
optimizations for custom types. This would be very useful on things like
matrix types, which would otherwise require heavy trickery with
expression templates in order to produce efficient code.


T

-- 
May you live all the days of your life. -- Jonathan Swift
January 29, 2013
Re: Implementing Half Floats in D
On Monday, 28 January 2013 at 23:58:40 UTC, Walter Bright wrote:
> On 1/28/2013 3:30 PM, Era Scarecrow wrote:
>> On Monday, 28 January 2013 at 23:11:11 UTC, Walter Bright 
>> wrote:
>>> http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674
>>>
>>> Anyone care to do the reddit honors?
>>
>> [quote]
>>   and crushed back down to 16 bytes for storage.
>> [/quote]
>>
>>  Should be bits. Otherwise it looks really well done.
>
> thank you. Sorry that didn't get caught in review!

"HalfFloat h = hf!1.3f;"

Maybe you could also demonstrate that it's possible to implement 
another literal syntax?
HalfFloat h = 1.3.hf;

some people will prefer that for sure.
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