Integer multiplication below n log n

(github.com)

23 points | by E-Reverance 1 hour ago

4 comments

  • shmoil 16 minutes ago
    I laughed out loud at the n lg n ^ (1 - 2^{-182}). It is so funny.
    • elcritch 3 minutes ago
      Wowzers!

      This also reaffirms my (wishful) thinking that if there’s a way to do FTL communication it’ll be something with an absurdly tiny factor like 2^-182 with a slight asymmetry in a probability somewhere.

      Then you’re not violating FTL, just gaining a very slight chance that you might know something FTL – probably.

    • qarl 11 minutes ago
      Dangit! I was betting on -183.
  • 12390asdjkas 4 minutes ago
    this is perfect for when i have an array of at LEAST 2^118000 items

    i will NEVER care about proposed multiplication speedups unless they are truly generalized

  • MinimalAction 12 minutes ago
    For the uninitiated, why is this interesting given it doesn't seem to be so much below the threshold?
    • Chinjut 7 minutes ago
      It's interesting because people wondered if it was possible to go below the threshold at all, that's all. Many suspected it was not possible.
  • infocollector 27 minutes ago
    This is pretty remarkable, IF someone can understand it :)
    • saagarjha 19 minutes ago
      I only skimmed the paper but it doesn’t see particularly dense, mostly just relying on college math?
      • cr4zy 12 minutes ago
        It's 50 pages and cites this other paper in the same repo:

        OpenAI. An explicit power saving for the exact discrete Fourier transform.

        Here's a random excerpt:

        8.3 The middle transform and the final permutation The factor QFt in (35) can be computed from a cyclic convolution and two pointwise phase multiplications. The chirp identity below performs the frequency change in Q without applying Q as a separate permutation of the array. The second identity shows how the retained source permutation R cancels when computing a convolution. Here ∗ denotes cyclic convolution on the product of the coordinate groups and a dot denotes coordinatewise multiplication.