John D. Cook
@johndcook.bsky.social
📤 1428
đź“Ą 8
đź“ť 60
Mathematician, data privacy consultant See also
@johndcook.mathstodon.xyz.ap.brid.gy
@christosargyrop.bsky.social
Kale sales and autism
www.wmbriggs.com/post/58413/
7 days ago
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Looking back at Martin Gardner’s RSA article
www.johndcook.com/blog/2025/08...
about 2 months ago
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Gluons, quarks, letters, and envelopes
www.johndcook.com/blog/2025/03...
7 months ago
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New post: Practical consequences of LLM tokenization details
www.johndcook.com/blog/2025/03...
7 months ago
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8 months ago
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Polynomial Encounters of the Third Kind
www.johndcook.com/blog/2025/02...
8 months ago
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Does DeepSeek demonstrate that we don’t need as much compute power as we thought?
www.johndcook.com/blog/2025/02...
8 months ago
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8 months ago
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New podcast interview just dropped. Protecting Privacy in the Age of AI: A Conversation with John Cook
www.trenegy.com/podcast/prot...
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Protecting Privacy in the Age of AI: A Conversation with John Cook
We 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...
https://www.trenegy.com/podcast/protecting-privacy-in-the-age-of-ai-a-conversation-with-john-cook
9 months ago
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How 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.
9 months ago
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Modal logic and science fiction
www.johndcook.com/blog/2022/01...
9 months ago
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Unix Time and a Modest Proposal
www.johndcook.com/blog/2024/12...
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Unix Time and a Modest Proposal
Why Unix time is not exactly what it is often described to be, and a proposal for fixing it.
https://www.johndcook.com/blog/2024/12/27/unix-time/
9 months ago
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Centered 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.
9 months ago
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Most popular posts of 2024
www.johndcook.com/blog/2024/12...
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Most popular posts of 2024
Most popular posts on this site in 2024, according to Hacker News.
https://www.johndcook.com/blog/2024/12/24/most-popular-2024/
9 months ago
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By 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...
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Twelve Days of Christmas and tetrahedral numbers
How 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
https://www.johndcook.com/blog/2009/12/08/tetrahedral-numbers/
10 months ago
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Intro to interval arithmetic. Applied to cosine iteration.
www.johndcook.com/blog/2024/12...
10 months ago
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If 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...
10 months ago
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A 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...
10 months ago
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How 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...
10 months ago
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Bi-elliptic transfer orbit maneuver
www.johndcook.com/blog/2024/12...
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Bi-elliptic transfer orbit maneuver
Comparing 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.
https://www.johndcook.com/blog/2024/12/03/bi-elliptic-transfer/
10 months ago
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Connecting powers of two and decibels
www.johndcook.com/blog/2022/02...
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Connecting powers of two and decibels
Powers of two give the approximate significant figures in integer decibels.
https://www.johndcook.com/blog/2022/02/28/power-two-lex/
10 months ago
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How to memorize the ASCII table
www.johndcook.com/blog/2022/05...
10 months ago
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10 months ago
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Sphere of influence
www.johndcook.com/blog/2022/12...
10 months ago
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My Mastodon posts are automatically posted to the Bluesky account
@johndcook.mathstodon.xyz.ap.brid.gy
10 months ago
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Asymmetric generation / verification costs
www.johndcook.com/blog/2024/11...
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Asymmetric generation / verification costs
Five examples of problems for which it is orders of magnitude easier to verify a solution than to generate a solution.
https://www.johndcook.com/blog/2024/11/30/generation-verification-costs/
10 months ago
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Number of elements in the nth row of the periodic table.
10 months ago
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Cobweb plots
www.johndcook.com/blog/2020/01...
10 months ago
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A more convenient squircle equation
www.johndcook.com/blog/2022/10...
10 months ago
2
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A knight’s tour magic square
www.johndcook.com/blog/2011/04...
10 months ago
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The hard part in becoming a command line wizard
www.johndcook.com/blog/2019/02...
10 months ago
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Vehicle Identification Number (VIN) check sum
www.johndcook.com/blog/2019/09...
10 months ago
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Differential privacy in a nutshell
www.johndcook.com/blog/differe...
10 months ago
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Gravitational attraction of stars and cows
www.johndcook.com/blog/2018/03...
10 months ago
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Harmonographs
www.johndcook.com/blog/2019/10...
10 months ago
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Math and software notes
www.johndcook.com/blog/notes/
10 months ago
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Confidential image-to-text
www.johndcook.com/blog/2024/11...
10 months ago
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Inverse optimization
www.johndcook.com/blog/2020/05...
11 months ago
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If 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.gy
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https://johndcook.mathstodon.xyz.ap.brid.gy
11 months ago
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New post: Perfect numbers
www.johndcook.com/blog/2024/11...
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Perfect numbers
Perfect numbers and their connections to Mersenne primes, triangular numbers, and binary sequences
https://www.johndcook.com/blog/2024/11/20/perfect-numbers/
11 months ago
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Trigonometric interpolation
www.johndcook.com/blog/2024/11...
11 months ago
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Jigsaw puzzles and SAT solvers
www.johndcook.com/blog/2024/11...
11 months ago
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A swing cover of heavy metal!
youtu.be/EIouvSWaFgM
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“Master of Puppets” (Metallica) Jazz Cover by Robyn Adele Anderson
YouTube video by Robyn Adele Anderson
https://youtu.be/EIouvSWaFgM
11 months ago
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I’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...
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Bluesky account
My Bluesky account and a bridge that will repost my Mastodon content to Bluesky.
https://www.johndcook.com/blog/2024/11/18/bluesky-account/
11 months ago
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The Postage Stamp Problem
www.johndcook.com/blog/2024/11...
11 months ago
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Mathematics of GPS
www.johndcook.com/blog/2024/11...
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The mathematics of GPS | Global Positioning Problem
Overview of the mathematics of determining your position by observing several satellites.
https://www.johndcook.com/blog/2024/11/16/the-mathematics-of-gps/
11 months ago
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reposted by
John D. Cook
John Golden
about 1 year ago
Quick
#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...
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Ptolemy's Theorem
Illustration of Ptolemy's Theorem.
https://www.geogebra.org/m/yrspy3mt
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over 1 year ago
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How much metadata is in a photo by default?
www.johndcook.com/blog/2024/02...
over 1 year ago
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“45 things I learned in the gulag”
www.theparisreview.org/blog/2018/06...
almost 2 years ago
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