I just now learned about this discussion and I see quite a few messages I
need to reply to.
I am very excited about a Julia version of unum arithmetic, and it does
seem like the ideal language for it. Alan Edelman, Deepak Vinchhi, and
Viral Shah proposed to create it with funding from A*STAR
What IEEE 754 did with negative zero is a half-baked attempt to represent
inexactness. Consider, for example, that the square root of negative zero
is defined to be negative zero. Unums have the same representation of zero
as floats in that the sign bit can be 0 or 1, but the sign bit is
Zenna,
If unums are used without the ubox method and some of the other techniques
described in the book (like tightest-possible evaluation in the *g*-layer
for a well-defined set of functions), they will indeed fall prey to two of
the main problems of interval arithmetic: the dependency
The chapter Permission to Guess explains how to round unums. The
guess function replaces an inexact unum with an exact one, either the one
closest to the midpoint if there is at least one more bit of fraction
precision available, or one of the endpoints if the ULP size is already as
small as
Actually, Jason, the book went through intense peer review repeatedly for
over a year before it hit the shelves. Horst Simon, the series editor,
vetted the manuscript and made sure William Kahan saw it as well. Kahan,
the guy behind the IEEE 754 Standard for floats and a Turing Award
Speaking of going out on a limb: are you aware of Mark Kikgard's work on GPU
accelerated path rendering?
http://www.slideshare.net/mobile/Mark_Kilgard/gtc-2014-nvidia-path-rendering
There is obvious *thematic* overlap, with the promise of faster, more accurate
2D graphics using LESS power.
My comment was only relating to ordinary floating point, I still don't
really understand unums.
On Thursday, 30 July 2015 14:47:20 UTC+1, Tom Breloff wrote:
Simon: if I understand what you're suggesting, you'd like to add a
rounding direction flag whenever the ubit is set that would indicate
On Wednesday, 29 July 2015 22:07:45 UTC+1, Steven G. Johnson wrote:
And I don't see a clear practical use-case for an inexact bit per value,
as opposed to a single inexact flag for a whole set of computations (as in
IEEE).
Probably not quite what others had in mind, but an
Simon: if I understand what you're suggesting, you'd like to add a
rounding direction flag whenever the ubit is set that would indicate
which direction you *would* round if you wanted to? I like this idea, as
it allows you to throw away the implicit open interval in favor of a
rounded exact value
+1 for grain of salt
On Saturday, July 25, 2015 at 9:11:54 AM UTC-4, Job van der Zwan wrote:
So I came across the concept of UNUMs on the Pony language mailing list
http://lists.ponylang.org/pipermail/ponydev/2015-July/71.html this
morning. I hadn't heard of them before, and a quick
How about moving the discussion here:
https://github.com/tbreloff/Unums.jl/issues/2
On Thu, Jul 30, 2015 at 1:09 PM, Jeffrey Sarnoff jeffrey.sarn...@gmail.com
wrote:
+1 for grain of salt
On Saturday, July 25, 2015 at 9:11:54 AM UTC-4, Job van der Zwan wrote:
So I came across the concept of
On Wednesday, July 29, 2015 at 5:31:12 PM UTC-4, Stefan Karpinski wrote:
The most compelling part of the proposal to me was the claim of
associativity, which I suppose comes along with the variable precision
since you can actually drop trailing bits that you can't get right.
I bought a
On Wednesday, July 29, 2015 at 4:59:02 PM UTC-4, Zenna Tavares wrote:
I read the book (well, somewhere between a skim and a proper read). It's
not formal but it is clear and the ideas are concise.
I actually think it's a pretty good example of how to explain an idea
without unnecessary
On Wed, Jul 29, 2015 at 4:59 PM, Zenna Tavares zennatava...@gmail.com
wrote:
As a result of these properties, unums can be closed under arithmetic
operations and won't hide your errors due to approximation.
I'm glad to hear this because this was that part that made me question the
whole
I read the book (well, somewhere between a skim and a proper read). It's
not formal but it is clear and the ideas are concise.
I actually think it's a pretty good example of how to explain an idea
without unnecessary jargon.
As for unums themselves, I am mostly convinced of his arguments on
On Sunday, July 26, 2015 at 4:06:05 AM UTC-4, Job van der Zwan wrote:
On Sunday, 26 July 2015 05:00:44 UTC+3, Scott Jones wrote:
There also doesn't seem to be any representation of -0.0, which from what
I've read, is important to represent negative underflows.
Apparently, his format
So on an impulse I got the ebook, and even for a physics dropout like me
it's surprisingly engaging and accessible! There's some stuff in there that
isn't mentioned in the online slides that might clarify the idea better.
For example, floats already have a way to represent the largest
On Sunday, July 26, 2015 at 7:51:51 AM UTC-4, Job van der Zwan wrote:
So on an impulse I got the ebook, and even for a physics dropout like me
it's surprisingly engaging and accessible! There's some stuff in there that
isn't mentioned in the online slides that might clarify the idea
On Sunday, 26 July 2015 05:00:44 UTC+3, Scott Jones wrote:
There also doesn't seem to be any representation of -0.0, which from what
I've read, is important to represent negative underflows.
Apparently, his format doesn't have underflow, or overflow. I'm still
trying to wrap my head around
How cool!
I don't know much about this matter, but this looks very exciting!
Julia seems to be a good fit to prototype this!
Am Samstag, 25. Juli 2015 15:11:54 UTC+2 schrieb Job van der Zwan:
So I came across the concept of UNUMs on the Pony language mailing list
On Saturday, 25 July 2015 23:34:45 UTC+3, Simon Byrne wrote:
Some HN discussion here:
https://news.ycombinator.com/item?id=9943589
Oh, hadn't seen that. The linked presentation is also more recent! I found
the slidecast version of it, where he presents the slides in podcast form.
Some HN discussion here:
https://news.ycombinator.com/item?id=9943589
I'd be keen to know more but he hasn't really published any details other
than his book
http://www.amazon.com/The-End-Error-Computing-Computational/dp/1482239868.
Based
on the free preview, it looks like a bit of a diatribe
This seems interesting, I'd like to know what David Sanders
(https://github.com/dpsanders) thinks of the math (I missed his talk at
JuliaCon, I'm waiting for the video, but the description made it sound
relevant).
There also doesn't seem to be any representation of -0.0, which from what
I've
23 matches
Mail list logo
