Hardware support for UNUM floating point arithmetic [pdf]

#1

Post by g0xA52A2A » Fri, Nov 03, 2017, 8:52 AM UTC

Hardware support for UNUM floating point arithmetic [pdf]
hal.inria.fr

Re: Hardware support for UNUM floating point arithmetic [pdf]

#2

Post by screeny05 » Fri, Nov 03, 2017, 3:31 PM UTC

please add a [PDF] to the header

Re: Hardware support for UNUM floating point arithmetic [pdf]

#3

Post by noahdesu » Fri, Nov 03, 2017, 3:50 PM UTC

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

Re: Hardware support for UNUM floating point arithmetic [pdf]

#4

Post by gjem97 » Fri, Nov 03, 2017, 3:54 PM UTC

screeny05 wrote: post #2

please add a [PDF] to the header

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

Re: Hardware support for UNUM floating point arithmetic [pdf]

#5

Post by [deleted] » Fri, Nov 03, 2017, 3:58 PM UTC

[deleted]

Re: Hardware support for UNUM floating point arithmetic [pdf]

#6

Post by petermonsson » Fri, Nov 03, 2017, 4:06 PM UTC

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?

Re: Hardware support for UNUM floating point arithmetic [pdf]

#7

Post by fdej » Fri, Nov 03, 2017, 4:14 PM UTC

petermonsson wrote: post #6

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?

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.

Re: Hardware support for UNUM floating point arithmetic [pdf]

#8

Post by j_s » Fri, Nov 03, 2017, 4:16 PM UTC

noahdesu wrote: post #3

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

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

Posit Paper: 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

Re: Hardware support for UNUM floating point arithmetic [pdf]

#9

Post by dEnigma » Fri, Nov 03, 2017, 4:16 PM UTC

gjem97 wrote: post #4

screeny05 wrote: post #2

please add a [PDF] to the header

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

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.

Re: Hardware support for UNUM floating point arithmetic [pdf]

#10

Post by iainmerrick » Fri, Nov 03, 2017, 4:41 PM UTC

petermonsson wrote: post #6

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?

If it's exactly reproducible on different hardware and software configurations, as seems to be one of the goals, that alone would be a useful improvement on IEEE754.