Mean distance to the sun and a new graph theorem
The mean distance, over time, between a planet and its star is approximately the semimajor axis of its orbit.
John D. Cook Consulting Substack
Highlights from blog posts
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Latest posts
Compressing Matrices and Correcting Codes
Hadamard matrices are very special matrices, so you’d expect that they could be determined by less data than the full matrix.
Applications of Hadamard Matrices
This morning I wrote a post, mentioned in the previous letter, about constructing Hadamard matrices.
Dogs, Shells, Retro Crypto, etc.
I’ve written several unrelated posts since the previous newsletter.
DNA, Range Reduction, and Apostrophes
The latest post is a brief note about how Bessel functions where used in discovering the structure of DNA.
Math with big numbers
My three latest post all deal with doing math on numbers too large to represent as a standard floating point number.
Mathematical Alchemy
My three latest posts have been about alchemy, sorta.
Physics, Special Functions, and Asymptotics
How exactly do special functions come up in physics? If you know the asymptotic form of a sequence, can you find the form of its cumulative sum?
Counting Trees and Solving Equations
Algebraic equations that come out of differential equations.
Hiding cryptographic keys in decks of cards
I ran across an article that showed how to store a 128-bit key in the permutations of a deck of 52 cards.