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

Anyone care to do the reddit honors?

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.

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/

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

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?

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.

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!

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

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

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.