Re:Hardware cost evaluation of the posit number system
by ori_b on Tuesday July 09, 2019 @11:28PM
(#20398947)
For a posit based float with 127 unique unisgned values. If you can tolerate that little precision, you can implement arithmetic as a smallish lookup table.
Re:Hardware cost evaluation of the posit number system
by benjaminogles on Tuesday July 09, 2019 @04:14PM
(#20396109)
I have not read the paper yet but the abstract says that they compared two hardware adders synthesized from C++ code. It seems like a fair comparison but I wonder whether it might be possible to hand design a much more efficient posit adder that is more competitive with hand designed floating point adders. I can see how the number of lookup tables used in synthesis would be proportional to the number of gates used on a dedicated chip though so maybe there would be no difference in comparing hand optimized adders on ICs.
Re:Hardware cost evaluation of the posit number system
by s_tec on Tuesday July 09, 2019 @03:54PM
(#20395898)
Bummer. The posit number system (http://www.johngustafson.net/pdfs/BeatingFloatingPoint.pdf) is super-cool, and its inventors often speak of its potential performance advantages. On the other hand, their claims did seems a little "too good to be true" - variable-width fields require mux gates, and somebody needs to pay for those.
Because there isn't much difference in that regard... values deviate no more than 25%, which is not insignificant, but not overwhelming either.
What I find even more suprising: Is there almost no difference in latencies for FP-operations between software-implemented and hardware-supported FPs?