John D. Cook @johndcook.bsky.social · 24/09/2025@christosargyrop.bsky.social Kale sales and autism www.wmbriggs.com/post/58413/ 1414128
John D. Cook @johndcook.bsky.social · 05/08/2025Looking back at Martin Gardner’s RSA article www.johndcook.com/blog/2025/08... 040
John D. Cook @johndcook.bsky.social · 17/03/2025Gluons, quarks, letters, and envelopes www.johndcook.com/blog/2025/03... 020
John D. Cook @johndcook.bsky.social · 09/03/2025New post: Practical consequences of LLM tokenization details www.johndcook.com/blog/2025/03... 020
John D. Cook @johndcook.bsky.social · 13/02/2025Polynomial Encounters of the Third Kind www.johndcook.com/blog/2025/02... 121
John D. Cook @johndcook.bsky.social · 03/02/2025Does DeepSeek demonstrate that we don’t need as much compute power as we thought? www.johndcook.com/blog/2025/02... 071
John D. Cook @johndcook.bsky.social · 16/01/2025New podcast interview just dropped. Protecting Privacy in the Age of AI: A Conversation with John Cook www.trenegy.com/podcast/prot...trenegy.comProtecting Privacy in the Age of AI: A Conversation with John CookWe discuss safeguarding sensitive information in data-intensive industries, the balance of preserving data utility and protecting privacy as AI applications raise new concerns, and methods like differ... 050
John D. Cook @johndcook.bsky.social · 01/01/2025How the day of the week for New Years Day goes through a 28 year cycle. The green diamonds represent leap years and the blue squares represent ordinary years. 070
John D. Cook @johndcook.bsky.social · 31/12/2024Modal logic and science fiction www.johndcook.com/blog/2022/01... 000
John D. Cook @johndcook.bsky.social · 27/12/2024Unix Time and a Modest Proposal www.johndcook.com/blog/2024/12...johndcook.comUnix Time and a Modest ProposalWhy Unix time is not exactly what it is often described to be, and a proposal for fixing it. 131
John D. Cook @johndcook.bsky.social · 25/12/2024Centered triangular numbers are the number of dots in images such as the one below. The nth centered triangular number equals 1 + 3n(n + 1)/2. 053
John D. Cook @johndcook.bsky.social · 24/12/2024Most popular posts of 2024 www.johndcook.com/blog/2024/12...johndcook.comMost popular posts of 2024Most popular posts on this site in 2024, according to Hacker News. 061
John D. Cook @johndcook.bsky.social · 20/12/2024By the nth day of Christmas, my true love had sent to me n(n+1)(n+2)/6 gifts. www.johndcook.com/blog/2009/12...johndcook.comTwelve Days of Christmas and tetrahedral numbersHow many gifts are there in the song Twelve Days of Christmas? Day 1: 1 gift Day 2: 1 + 2 = 3 gifts Day 3: 1 + 2 + 3 = 6 gifts … Day 12: 1 + 2 + 3 + … + 12 = 78 gifts The number of gifts on day 040
John D. Cook @johndcook.bsky.social · 19/12/2024Intro to interval arithmetic. Applied to cosine iteration. www.johndcook.com/blog/2024/12... 041
John D. Cook @johndcook.bsky.social · 17/12/2024If you press the cosine key on a calculator over and over, you always get stuck on the same number. This post takes a more sophisticated look at a child’s amusement. www.johndcook.com/blog/2024/12... 0101
John D. Cook @johndcook.bsky.social · 16/12/2024A golden hospital gown is an allusion to The Emperor’s New Clothes, except the emperor is somewhere between sumptuously clothed and naked. www.johndcook.com/blog/2024/12... 010
John D. Cook @johndcook.bsky.social · 09/12/2024How many ways can you select six points in the plane so that every subset of three points forms the vertices of an isosceles triangle? www.johndcook.com/blog/2024/12... 050
John D. Cook @johndcook.bsky.social · 08/12/2024Bi-elliptic transfer orbit maneuver www.johndcook.com/blog/2024/12...johndcook.comBi-elliptic transfer orbit maneuverComparing bi-elliptic transfer orbit and the Hohmann transfer orbit. The latter can be more efficient when the target orbit is far larger than the initial orbit. 050
John D. Cook @johndcook.bsky.social · 08/12/2024Connecting powers of two and decibels www.johndcook.com/blog/2022/02...johndcook.comConnecting powers of two and decibelsPowers of two give the approximate significant figures in integer decibels. 040
John D. Cook @johndcook.bsky.social · 07/12/2024How to memorize the ASCII table www.johndcook.com/blog/2022/05... 070
John D. Cook @johndcook.bsky.social · 03/12/2024Sphere of influence www.johndcook.com/blog/2022/12... 061
John D. Cook @johndcook.bsky.social · 30/11/2024My Mastodon posts are automatically posted to the Bluesky account @johndcook.mathstodon.xyz.ap.brid.gy 0111
John D. Cook @johndcook.bsky.social · 30/11/2024Asymmetric generation / verification costs www.johndcook.com/blog/2024/11...johndcook.comAsymmetric generation / verification costsFive examples of problems for which it is orders of magnitude easier to verify a solution than to generate a solution. 150
John D. Cook @johndcook.bsky.social · 29/11/2024Number of elements in the nth row of the periodic table. 090
John D. Cook @johndcook.bsky.social · 28/11/2024A more convenient squircle equation www.johndcook.com/blog/2022/10... 2102
John D. Cook @johndcook.bsky.social · 28/11/2024A knight’s tour magic square www.johndcook.com/blog/2011/04... 020
John D. Cook @johndcook.bsky.social · 27/11/2024The hard part in becoming a command line wizard www.johndcook.com/blog/2019/02... 0130
John D. Cook @johndcook.bsky.social · 26/11/2024Vehicle Identification Number (VIN) check sum www.johndcook.com/blog/2019/09... 010
John D. Cook @johndcook.bsky.social · 26/11/2024Differential privacy in a nutshell www.johndcook.com/blog/differe... 061
John D. Cook @johndcook.bsky.social · 24/11/2024Gravitational attraction of stars and cows www.johndcook.com/blog/2018/03... 081
John D. Cook @johndcook.bsky.social · 23/11/2024Math and software notes www.johndcook.com/blog/notes/ 150
John D. Cook @johndcook.bsky.social · 21/11/2024Confidential image-to-text www.johndcook.com/blog/2024/11... 030
John D. Cook @johndcook.bsky.social · 20/11/2024Inverse optimization www.johndcook.com/blog/2020/05... 060
John D. Cook @johndcook.bsky.social · 20/11/2024If you’d like to see my blog posts as soon as they’re posted, please follow the Bluesky bridge to my Mathstodon account: johndcook.mathstodon.xyz.ap.brid.gyjohndcook.mathstodon.xyz.ap.brid.gy 050
John D. Cook @johndcook.bsky.social · 20/11/2024New post: Perfect numbers www.johndcook.com/blog/2024/11...johndcook.comPerfect numbersPerfect numbers and their connections to Mersenne primes, triangular numbers, and binary sequences 050
John D. Cook @johndcook.bsky.social · 19/11/2024Trigonometric interpolation www.johndcook.com/blog/2024/11... 040
John D. Cook @johndcook.bsky.social · 19/11/2024Jigsaw puzzles and SAT solvers www.johndcook.com/blog/2024/11... 010
John D. Cook @johndcook.bsky.social · 19/11/2024A swing cover of heavy metal! youtu.be/EIouvSWaFgMyoutu.be“Master of Puppets” (Metallica) Jazz Cover by Robyn Adele AndersonYouTube video by Robyn Adele Anderson 021
John D. Cook @johndcook.bsky.social · 18/11/2024I’ve set up a bridge that is supposed to repost my Mastodon content to Bluesky. I think it takes some time for the setup to propagate. www.johndcook.com/blog/2024/11...johndcook.comBluesky accountMy Bluesky account and a bridge that will repost my Mastodon content to Bluesky. 082
John D. Cook @johndcook.bsky.social · 18/11/2024The Postage Stamp Problem www.johndcook.com/blog/2024/11... 040
John D. Cook @johndcook.bsky.social · 17/11/2024Mathematics of GPS www.johndcook.com/blog/2024/11...johndcook.comThe mathematics of GPS | Global Positioning ProblemOverview of the mathematics of determining your position by observing several satellites. 1130
Reposted by John D. CookJohn Golden @johngolden.bsky.social · 25/08/2024Quick #geogebra applet for Ptolemy's Theorem, a sweet extension of the Pythagorean Theorem. www.geogebra.org/m/yrspy3mt was reminded of it by @johndcook.bsky.social www.johndcook.com/blog/2024/08...geogebra.orgPtolemy's TheoremIllustration of Ptolemy's Theorem. 072
John D. Cook @johndcook.bsky.social · 13/02/2024How much metadata is in a photo by default? www.johndcook.com/blog/2024/02... 050
John D. Cook @johndcook.bsky.social · 07/11/2023“45 things I learned in the gulag” www.theparisreview.org/blog/2018/06... 010
