Jan Marthedal Rasmussen
@janmr.com
Programmer, amateur mathematician, BJJ brown belt
https://janmr.com
https://janmr.com
How to Draw a Straight Line (Peaucellier–Lipkin linkage) www.futilitycloset.com/2014/12/05/s... #math #geometry
Straight and Narrow - Futility Closet
A.B. Kempe’s provocatively titled How to Draw a Straight Line (1877) addresses a fundamental question. In the Elements, Euclid derives his results by drawing straight lines and circles. We can draw a ...
www.futilitycloset.com
December 10, 2025 at 6:18 AM
How to Draw a Straight Line (Peaucellier–Lipkin linkage) www.futilitycloset.com/2014/12/05/s... #math #geometry
December 9, 2025 at 6:53 AM
Two Notes on Notation by Donald E. Knuth (Iverson’s convention and Stirling numbers) arxiv.org/abs/math/920... #math #notation
December 8, 2025 at 8:14 AM
Two Notes on Notation by Donald E. Knuth (Iverson’s convention and Stirling numbers) arxiv.org/abs/math/920... #math #notation
December 7, 2025 at 11:45 AM
Langford pairs: Arrange the 2n numbers {1, 1, 2, 2, ..., n, n} such that exactly k numbers occur between the two appearances of each digit k dialectrix.com/langford.html #math #combinatorics
December 6, 2025 at 2:52 PM
Langford pairs: Arrange the 2n numbers {1, 1, 2, 2, ..., n, n} such that exactly k numbers occur between the two appearances of each digit k dialectrix.com/langford.html #math #combinatorics
Continued Fractions and Continuants janmr.com/posts/contin... #math #computerscience #algoritms #continuedfractions
December 5, 2025 at 6:39 AM
Continued Fractions and Continuants janmr.com/posts/contin... #math #computerscience #algoritms #continuedfractions
Computing the Greatest Common Divisor janmr.com/posts/comput... #math #programming #number-theory #algorithm
December 2, 2025 at 1:52 PM
Computing the Greatest Common Divisor janmr.com/posts/comput... #math #programming #number-theory #algorithm
Guido on introducing the shortcut conditional expression to Python.
Some usages are "intentionally ugly" and finishes by adding "It's still my language! :-)".
mail.python.org/pipermail/py...
Some usages are "intentionally ugly" and finishes by adding "It's still my language! :-)".
mail.python.org/pipermail/py...
December 1, 2025 at 2:19 PM
Guido on introducing the shortcut conditional expression to Python.
Some usages are "intentionally ugly" and finishes by adding "It's still my language! :-)".
mail.python.org/pipermail/py...
Some usages are "intentionally ugly" and finishes by adding "It's still my language! :-)".
mail.python.org/pipermail/py...
Useful Properties of the Floor and Ceil Functions janmr.com/posts/useful... #floor #ceil #functions #math #programming
November 30, 2025 at 10:15 AM
Useful Properties of the Floor and Ceil Functions janmr.com/posts/useful... #floor #ceil #functions #math #programming
Google humor: Did you mean recursion? www.google.com/search?q=rec...
November 29, 2025 at 3:20 PM
Google humor: Did you mean recursion? www.google.com/search?q=rec...
November 28, 2025 at 7:53 AM
Reposted by Jan Marthedal Rasmussen
![Comic. Panels up to the 10-year point are grayed out. New panels since the Ten Years comic, which chronicles the first ten years of PERSON 1's journey with cancer: (1) [two people in bed] PERSON 1 (woman): One more chapter? PERSON 2 (man): Don’t we both have to get up early? PERSON 1: Nnnnnggggh PERSON 2: Sure, good point. (2) [many people wearing masks, walking while looking at graphs on their phones] (3) [birds landing on people] PERSON 2 in beanie and scarf: Hah! They like *my* seeds best. PERSON 1 in scarf holding phone with a bird sitting on it: Wait, how do I take a picture of this one? (4) [two people rowing boats with tree landscape] (5) [Person 1 carries overflowing stack of things to Person 2 in bed] PERSON 1: I brought you honey lemon tea, more pillows, a cinnamon roll, Tylenol, another blanket, a– PERSON 2: It was just Appendicitis, I’m really– PERSON 1: *It is my turn to take care of you and I am going to do it right!* (6) [Two people in car] (7) [still in car) PERSON 1: Oh my god. PERSON 2: Oh my god. (8) [car driving] PERSON 1: Pull over! PERSON 2: I am! (9) [both people get out of car] (10) [Large colored panel of aurora borealis over water with both people looking on] (11) [Person 1 sits against tree while Person 2 lies on the ground] PERSON 1: Fifteen years. No sign of the cancer. (12) I *am* having some weird symptoms. Joint pain. Fatigue. I think I’m losing my close-up vision. PERSON 2: Yeah. Me too. (13) PERSON 2: I think we’re getting old. (14) PERSON 1: I guess that’s okay. PERSON 2: It’s all I wanted.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cz73r7iyiqn26upot4jtjdhk/bafkreihwhjblp5lyiwp63ouar7ocfea7evmckytoeo7rkfuoo4gw5rnrra@jpeg)
November 26, 2025 at 10:32 PM
Modern Computer Arithmetic, a book about algorithms for performing arithmetic, and their implementation on modern computers maths-people.anu.edu.au/~brent/pub/p... members.loria.fr/PZimmermann/... #multiple-precision #arithmetic #algorithms #online #book
November 27, 2025 at 6:53 AM
Modern Computer Arithmetic, a book about algorithms for performing arithmetic, and their implementation on modern computers maths-people.anu.edu.au/~brent/pub/p... members.loria.fr/PZimmermann/... #multiple-precision #arithmetic #algorithms #online #book
Nice Proof of a Geometric Progression Sum janmr.com/posts/nice-g... #math #visualization #visual-proof
November 26, 2025 at 5:59 AM
Nice Proof of a Geometric Progression Sum janmr.com/posts/nice-g... #math #visualization #visual-proof
Math.sumPrecise developer.mozilla.org/en-US/docs/W...
Math.sumPrecise() - JavaScript | MDN
The Math.sumPrecise() static method takes an iterable of numbers and returns the sum of them. It is more precise than summing them up in a loop, because it avoids floating point precision loss in inte...
developer.mozilla.org
August 1, 2025 at 6:26 AM
Math.sumPrecise developer.mozilla.org/en-US/docs/W...
A leap year check in three instructions hueffner.de/falk/blog/a-...
A leap year check in three instructions
How to test for leap years (until year 102499) in the proleptic Gregorian calendar with just three 32-bit instructions, with detailed explanation of the bit-level tricks.
hueffner.de
May 22, 2025 at 11:57 AM
A leap year check in three instructions hueffner.de/falk/blog/a-...
Full unicode emoji list unicode.org/emoji/charts...
unicode.org
May 20, 2025 at 7:47 AM
Full unicode emoji list unicode.org/emoji/charts...
An ongoing multi-author open source project to formalise a proof of Fermat's Last Theorem in the Lean theorem prover imperialcollegelondon.github.io/FLT/ #lean
Fermat’s Last Theorem
An ongoing multi-author open source project to formalise a proof of Fermat’s Last Theorem in the Lean theorem prover.
imperialcollegelondon.github.io
May 19, 2025 at 10:53 AM
An ongoing multi-author open source project to formalise a proof of Fermat's Last Theorem in the Lean theorem prover imperialcollegelondon.github.io/FLT/ #lean
Fast and maintainable patterns for fetching from a database by @sophiebits.com sophiebits.com/2020/01/01/f...
Fast and maintainable patterns for fetching from a database
sophiebits.com
May 7, 2025 at 5:09 AM
Fast and maintainable patterns for fetching from a database by @sophiebits.com sophiebits.com/2020/01/01/f...
Celebrate 50 years of Microsoft with the company’s original source code by Bill Gates www.gatesnotes.com/home/home-pa...
Celebrating 50 years of Microsoft | Bill Gates
This one piece of code led to a half century of innovation from Microsoft.
www.gatesnotes.com
April 4, 2025 at 11:44 AM
Celebrate 50 years of Microsoft with the company’s original source code by Bill Gates www.gatesnotes.com/home/home-pa...
Free math texts by Jim Hefferon (Linear Algebra, Theory of Computation, Introduction to Proofs) hefferon.net
Free Math Texts and more, from Jim Hefferon
Free Texts in Mathematics and Computer Science and more, from Jim Hefferon
hefferon.net
April 2, 2025 at 12:11 PM
Free math texts by Jim Hefferon (Linear Algebra, Theory of Computation, Introduction to Proofs) hefferon.net
@acm.org ACM has named Andrew G. Barto and Richard S. Sutton as the recipients of the 2024 ACM A.M. Turing Award for developing the conceptual and algorithmic foundations of reinforcement learning awards.acm.org/about/2024-t...
Andrew Barto and Richard Sutton are the recipients of the 2024 ACM A.M. Turing Award for developing the conceptual and algorithmic foundations of reinforcement learning.
Andrew Barto and Richard Sutton as the recipients of the 2024 ACM A.M. Turing Award for developing the conceptual and algorithmic foundations of reinforcement learning. In a series of papers beginning...
awards.acm.org
March 5, 2025 at 10:31 AM
@acm.org ACM has named Andrew G. Barto and Richard S. Sutton as the recipients of the 2024 ACM A.M. Turing Award for developing the conceptual and algorithmic foundations of reinforcement learning awards.acm.org/about/2024-t...
Reposted by Jan Marthedal Rasmussen
Watch Firefly land on the Moon! After identifying surface hazards and selecting a safe landing site, #BlueGhost landed directly over the target in Mare Crisium. A historic moment on March 2 we'll never forget. We have Moon dust on our boots! #BGM1
youtu.be/NpHhEybJdxg
youtu.be/NpHhEybJdxg
Moon Landing - Firefly Blue Ghost Makes History
YouTube video by Firefly Aerospace
youtu.be
March 4, 2025 at 6:56 PM
Watch Firefly land on the Moon! After identifying surface hazards and selecting a safe landing site, #BlueGhost landed directly over the target in Mare Crisium. A historic moment on March 2 we'll never forget. We have Moon dust on our boots! #BGM1
youtu.be/NpHhEybJdxg
youtu.be/NpHhEybJdxg