Stanford Online
5 HN recommenders · recommended in 9 months, 2017–2021
1:31:28 · 33K views · Feb 3, 2017
John Gustafson presents posits, a proposed drop-in replacement for IEEE 754 floats that is simpler in hardware and more flexible in precision. The seminar includes a live demo and machine learning results.
Cited in floating-point threads as the main introduction to posits and unums as an alternative to IEEE floats.
13 comments from Hacker News
Well unums in particular (especially the new type 3 "posits" ones) are very interesting and practical for hardware implementation. John Gustafson, the creator of unums, gave the first talk on type 3 unums at Stanford earlier this month, and there are already multiple hardware implementation efforts (one of which I am indirectly overseeing). While many people have recently hyped up low precision floating point for things like machine learning, Posits provide greater dynamic range AND greater accuracy for very few bits (as low as four, but with good ML starting 8 to 10 bits). On top of all of that, it costs less area and power in silicon than IEEE hardware. Check out the talk: this video
I'm very surprised nobody has brought up John Gustafson's Unum work. His latest iteration is the posit, which he presented at Stanford earlier this month[0][1] EDIT: apologies to CalChris[2]. What I should have said is discussed Gustafson's Unum work. [0] this video (relevant question at 1h22m37s) [1] [LINK] [2] [LINK]
You may like: this video It turns out the math is slightly harder but it's faster than IEEE FP in hardware, probably because of less conditionals in the spec. There is better performance in terms of numerical accuracy at the cost of substantially more difficult error analysis. Disclaimer: I'm in the video.
For anyone interested in this sort of thing you'd probably also be interested in John Gustafson's work on unums/posits. Here's a nice introductory presentation this video
Have you seen "Stanford Seminar: Beyond Floating Point: Next Generation Computer Arithmetic"? this video