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John D. Cook

@johndcook.mathstodon.xyz.ap.brid.gy
226 followers 0 following 627 posts

Consultant in applied mathematics and data privacy www.johndcook.com [bridged from mathstodon.xyz/@johndcook on the fediverse by fed.brid.gy ]

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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 21/10/2026
Deliberate imperfection www.johndcook.com/blog/2026/10/21/d…
sheet music for fate motif
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 17/10/2026
Latest newsletter: Lagrange Points, Backdoors, and Edgar Allan Poe johndcookconsulting.substack.com/p/…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 16/10/2026
Monoliths and Lagrange points www.johndcook.com/blog/2026/10/16/m…
MISSION ANALYSIS: COMPOSITION OF SECOND MONOLITY ... UNKNOWN. POSITION OF SECOND MONOLITH ... LA GRANGE POINT BETWEEN JUPITER AND IO. POSSITION OF U.S.S. DISCOVERY ... ORBIT AROUND IO. CONDITION OF U.S.S. DISCOVERY ... UNKNOWN.
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 14/10/2026
Pascal's triangle with odd numbers highlighted. LaTeX package for creating the illustration. www.johndcook.com/blog/2026/10/14/l…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 14/10/2026
The regions with the same color have the same area. www.johndcook.com/blog/2026/10/14/p…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 14/10/2026
The differential equation implicit in The Pit and the Pendulum by Edgar Allan Poe. www.johndcook.com/blog/2026/10/14/p…
Book cover
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 13/10/2026
The harmonic triangle www.johndcook.com/blog/2026/10/13/h…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 12/10/2026
Categorical models of logics www.johndcook.com/blog/2026/10/12/c…
Table summarizing the Curry-Howard-Lambek corresonodence between logic and category theory
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 08/10/2026
New post: Privacy Policies and Modal Logic www.johndcook.com/blog/2026/10/08/p…
Temporal logic operators: box, diamond, box minus, diamond minus
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 07/10/2026
Lissajous and Bowditch www.johndcook.com/blog/2026/10/06/l…
Lissajous curve
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 03/10/2026
Miquel's pivot theorem www.johndcook.com/blog/2026/10/03/m…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 22/09/2026
New post: Nathaniel Bowditch A self-taught mathematician who corrected errors in Newton and filled in gaps in Laplace www.johndcook.com/blog/2026/09/22/n…
Cover of the book Carry On, Mr. Bowditch
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 17/09/2026
Empirical fractal www.johndcook.com/blog/2026/09/17/e…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 17/09/2026
Vintage business cards and phone words www.johndcook.com/blog/2026/09/17/p…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 16/09/2026
New post on the subtlety of word vectors www.johndcook.com/blog/2026/09/16/c…
coffee + milk ?= latte
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 15/09/2026
Vector embeddings of words can approximately satisfy conceptual arithmetic. But when you look at the numbers, this might not seem true. The numbers need to be placed in context. www.johndcook.com/blog/2026/09/15/c…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 10/09/2026
Bayesian OCR www.johndcook.com/blog/2026/09/10/b…
blurry eszett or beta
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 07/09/2026
The error rate in Google's Ngram data is much higher than I thought. The graph below cannot be right. www.johndcook.com/blog/2026/09/07/n…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 04/09/2026
Unicode-based easter egg in NVIDIA's offer to buy Hugging Face www.johndcook.com/blog/2026/09/03/h…
Hugging Face emoji
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 23/08/2026
The difference orbit inclination makes www.johndcook.com/blog/2026/08/22/i…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 20/08/2026
New post: AI-generated ASCII diagrams www.johndcook.com/blog/2026/08/20/a…
ASCII art diagram of DES encryption round
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 19/08/2026
Ron Graham's hexagon has diameter 1 but a larger area than a regular hexagon with diameter 1. www.johndcook.com/blog/2026/08/18/b…
Graham's hexagon
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 18/08/2026
The recently proven imbalance conjecture www.johndcook.com/blog/2026/08/18/t…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 14/08/2026
How NASA used Hadamard matrices to transmit photos from Mars. www.johndcook.com/blog/2026/08/13/m…
Mariner 9's photo of the Olympus Mons caldera
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 11/08/2026
Distribution of dog names in New York City www.johndcook.com/blog/2026/08/11/d…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 09/08/2026
DNA and Bessel functions www.johndcook.com/blog/2026/08/09/d…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 05/08/2026
Enumerating rooted trees and non-overlapping circles www.johndcook.com/blog/2026/08/05/e…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 01/08/2026
Counting rooted trees www.johndcook.com/blog/2026/08/01/c…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 30/07/2026
Comparing forward Euler and symplectic Euler ODE solvers on the preditor-prey equations. www.johndcook.com/blog/2020/09/12/s…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 28/07/2026
New post: Hiding data in permutations www.johndcook.com/blog/2026/07/27/h…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 26/07/2026
New post: The exp_q function www.johndcook.com/blog/2026/07/26/e…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 22/07/2026
Find all solutions to sin(x degrees) = sin(x radians). www.johndcook.com/blog/2026/07/22/d…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 20/07/2026
Volume to Area ratio for Regular Solids www.johndcook.com/blog/2026/07/20/v…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 20/07/2026
Solving a chess puzzle by asking Grok 4.5 to generate Lean 4 and Prolog code. www.johndcook.com/blog/2026/07/20/g…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 17/07/2026
Visualizing the number of medical codes (ICD-10 and HCPCS) that start with each letter. www.johndcook.com/blog/2026/07/17/v…
ICD-10 codes per letter
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 14/07/2026
How ICD-10 chapters and code letters relate www.johndcook.com/blog/2026/07/14/i…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 12/07/2026
New post: Posterior varaince www.johndcook.com/blog/2026/07/12/p…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 10/07/2026
Linear interpolation calculator www.johndcook.com/interpolator.html
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 06/07/2026
Reproducing a geometry theorem diagram www.johndcook.com/blog/2026/07/06/a…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 04/07/2026
The following number 888 ... 333 is prime. In the image below, the 3's are red, the 1's are white, and the 8's are blue. There are four 9's in the image that are black.
American flag prime
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 30/06/2026
Silver Rectangles and the Ways of Kings www.johndcook.com/blog/2026/06/30/s…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 29/06/2026
Who you gonna believe: Grok or the docs? Neither. Do a test. www.johndcook.com/blog/2026/06/29/w…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 28/06/2026
Unpacking a bash brace expansion example by Peter Krummins. www.johndcook.com/blog/2026/06/27/b…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 27/06/2026
Heights of harmonic numbers www.johndcook.com/blog/2026/06/27/h…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 25/06/2026
Hart's theorem www.johndcook.com/blog/2026/06/25/h…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 25/06/2026
Incircles and excircles of Pythagorean triangles www.johndcook.com/blog/2026/06/25/i…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 25/06/2026
The Star Trek lemma www.johndcook.com/blog/2026/06/24/s…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 22/06/2026
Queens of a prime order chessboard www.johndcook.com/blog/2026/06/21/q…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 20/06/2026
Placing all six chess pieces on a 6 by 5 board so that no piece attacks another. Solution using Claude to generate Z3/Python. www.johndcook.com/blog/2026/06/20/z…
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John D. Cook @johndcook.mathstodon.xyz.ap.brid.gy · 16/06/2026
Testing pentagonal numbers www.johndcook.com/blog/2026/06/15/t…
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