Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
Skins
  • Light
  • Brite
  • Cerulean
  • Cosmo
  • Flatly
  • Journal
  • Litera
  • Lumen
  • Lux
  • Materia
  • Minty
  • Morph
  • Pulse
  • Sandstone
  • Simplex
  • Sketchy
  • Spacelab
  • United
  • Yeti
  • Zephyr
  • Dark
  • Cyborg
  • Darkly
  • Quartz
  • Slate
  • Solar
  • Superhero
  • Vapor

  • Default (No Skin)
  • No Skin
Collapse

The New Coffee Room

  1. TNCR
  2. General Discussion
  3. Puzzle time - the Fibonacci numbers

Puzzle time - the Fibonacci numbers

Scheduled Pinned Locked Moved General Discussion
31 Posts 4 Posters 387 Views
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • jon-nycJ Online
    jon-nycJ Online
    jon-nyc
    wrote on last edited by jon-nyc
    #22

    No, the cycle length of Fib mod (2^n) = 3*2^(n-1))

    Check Fmod2, Fmod4, Fmod8, Fmod16 etc for their cycle lengths. You’ll get 3,6,12,24,48 etc. I’m wondering if it holds. I think it will.

    The whole reason we call them illegal aliens is because they’re subject to our laws.

    1 Reply Last reply
    • KlausK Offline
      KlausK Offline
      Klaus
      wrote on last edited by
      #23

      Here's a list of pairs where the first number shows the "n" (but only for powers of 2) and the second one the associated cycle length. Maybe I missunderstood something but your conjecture doesn't seem to hold.

      [(2,6),(4,24),(8,60),(16,24),(32,36),(64,120),(128,420),(256,264),(512,516),(1024,72),(2048,600),(4096,1368),(8192,720)]
      
      1 Reply Last reply
      • jon-nycJ Online
        jon-nycJ Online
        jon-nyc
        wrote on last edited by jon-nyc
        #24

        But your original list is this one:

        (left side numbering mine, right side list yours)

        3e9774ed-e059-4cd4-956f-c8646a08d27b-image.png

        The whole reason we call them illegal aliens is because they’re subject to our laws.

        1 Reply Last reply
        • KlausK Offline
          KlausK Offline
          Klaus
          wrote on last edited by
          #25

          Ah, looks like an "off by two" error somewhere. Hmm....

          1 Reply Last reply
          • KlausK Offline
            KlausK Offline
            Klaus
            wrote on last edited by Klaus
            #26

            Turned out to be two "off by 1" errors that have to do with indices starting at 0 and not 1.

            What about this result?

            [(2,3),(4,6),(8,12),(16,24),(32,48),(64,96),(128,192),(256,384),(512,768),(1024,1536),(2048,3072),(4096,6144),(8192,12288)]
            
            1 Reply Last reply
            • KlausK Offline
              KlausK Offline
              Klaus
              wrote on last edited by Klaus
              #27

              It looks like linear relations between the cycle length happen quite frequently. This is a scatter plot of the cycle lengths I computed above (haven't used R in a while - fun for plotting data!). Observe all the dotted lines. The points you identified are on one of those lines. Also interesting to see a few outliers.

              440d6f5b-c0a6-4d2d-b301-7d3d66c1fafd-image.png

              I have marked the points you are interested in in red. You see that there are way more points on that line.

              1 Reply Last reply
              • jon-nycJ Online
                jon-nycJ Online
                jon-nyc
                wrote on last edited by
                #28

                Interesting.

                So it turns out Fibonacci cycle lengths a thing people study. They’re called Pisano numbers and understanding them is really about understanding Pisano numbers for prime powers.

                A neat property is that if n and m are coprime then period(mn) is least common multiple of period(n) and period(m).

                The whole reason we call them illegal aliens is because they’re subject to our laws.

                1 Reply Last reply
                • jon-nycJ Online
                  jon-nycJ Online
                  jon-nyc
                  wrote on last edited by
                  #29

                  Wait a minute, is that really your graph up there? This is from Wiki

                  396851CA-71EE-4E8B-AB14-42964B4121AC.png

                  The whole reason we call them illegal aliens is because they’re subject to our laws.

                  1 Reply Last reply
                  • KlausK Offline
                    KlausK Offline
                    Klaus
                    wrote on last edited by Klaus
                    #30

                    Yes, it's my graph. I haven't seen the WIki graph yet, but it shows the same data, so of course it's similar. It's an interesting coincidence that they also cut off at 10,000.

                    1 Reply Last reply
                    • KlausK Offline
                      KlausK Offline
                      Klaus
                      wrote on last edited by
                      #31

                      Just for fun, here's the continuation of the dataset for cycle lengths up to 20000.

                      1549ea7c-ea85-4eca-aea0-3b73c980f9aa-image.png

                      1 Reply Last reply

                      Hello! It looks like you're interested in this conversation, but you don't have an account yet.

                      Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.

                      With your input, this post could be even better 💗

                      Register Login
                      Reply
                      • Reply as topic
                      Log in to reply
                      • Oldest to Newest
                      • Newest to Oldest
                      • Most Votes


                      • Login

                      • Don't have an account? Register

                      • Login or register to search.
                      • First post
                        Last post
                      0
                      • Categories
                      • Recent
                      • Tags
                      • Popular
                      • Users
                      • Groups