
Hardware support for UNUM floating point arithmetic [pdf] - gbrown_
https://hal.inria.fr/hal-01618698/document
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noahdesu
Woah, really cool. My understanding is that Posit, the successor to unum
versions 1 and 2, is the future and is much easier to implement in hardware
[0].

[0]: [https://posithub.org/about](https://posithub.org/about)

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j_s
There is a Posit BoF at SC17 (supercomputing) Nov 14 DEN:
[http://sc17.supercomputing.org/presentation/?id=bof135&sess=...](http://sc17.supercomputing.org/presentation/?id=bof135&sess=sess333)

Posit Paper:
[http://johngustafson.net/pdfs/BeatingFloatingPoint.pdf](http://johngustafson.net/pdfs/BeatingFloatingPoint.pdf)

 _A new data type called a posit is designed as a direct drop-in replacement
for IEEE Standard 754 floating-point numbers (floats). Unlike earlier forms of
universal number (unum) arithmetic, posits do not require interval arithmetic
or variable size operands; like floats, they round if an answer is inexact.
However, they provide compelling advantages over floats, including larger
dynamic range, higher accuracy, better closure, bitwise identical results
across systems, simpler hardware, and simpler exception handling._

source:
[https://twitter.com/daniel_bilar/status/920252363159539712](https://twitter.com/daniel_bilar/status/920252363159539712)

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petermonsson
I am confused. I see half the performance and 3-5x the area of IEEE754, but
the conclusion is that UNUM is comparable. That would not be my conclusion.
What am I missing?

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fdej
The idea is that computers spend much more energy moving data between the
processor and memory than actually processing the data. Unums use a variable
length encoding which makes processing more costly but reduces the amount of
data transfer. At least in theory; whether this is a net benefit remains to be
proven.

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screeny05
please add a [PDF] to the header

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gjem97
Just wondering: why is it useful to know it's a PDF before clicking?

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dEnigma
In my case, while I'm on my phone, the pdf is automatically downloaded and
opened in a different app; so it is nice to have a warning.

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pasbesoin
It's also something of a legacy convention (though one I prefer to maintain),
from when PDF files were a leading vector for malware.

Though even back then, malware concerns aside, people would curse when a link
caused Acrobat Reader (or, depending on one's system, the full Acrobat
program) to unexpectedly fire up. Once upon a time, browsers didn't have
integrated PDF handling.

And, even now, with integrated PDF handling, said handling is not proof
against exploits.

