Some time ago, I wrote a little shell script called next, which used the date command to output the date some number of weekdays after the current date. So if I ran it today (Thursday, May 2, 2024) with this invocation, | Continue reading
I saw Steve Mould’s latest video this morning. It’s about mechanisms that store elastic energy and release it quickly. His examples come from insects and human-made devices. You should take 15 minutes and watch it. | Continue reading
After writing the last post, I decided to do the calculations necessary to make Newmark’s influence chart. | Continue reading
In a post this morning, John D. Cook listed several types of partial differential equation that are unusual in that they can be solved analytically. The last one in his list caught my eye because it’s one that I know pretty well from the theory of elasticity: Boussinesq’s equatio … | Continue reading
This morning, I read a short article describing certain deficiencies in Bing Copilot when it comes to doing math. The article interested me for two reasons: | Continue reading
A couple of days ago, two tweets appeared in my Mastodon timeline1 that got me thinking about how and why I type special characters on my Mac. The first was from Cabel Sasser, | Continue reading
One of the things I planned to do upon retirement was study topics that I had missed, or nearly missed, in school. Some of these would be things that were barely touched on in class; some would be material that was in the textbook but not covered in class; and some would be topic … | Continue reading
I tried the Apple Sports app when it came out in February and abandoned it almost immediately. Lots was written about Sports in its first couple of weeks, but I was on a blogging hiatus back then. I’ve recently looked at it again to see if I was too hasty or if its failings had b … | Continue reading
In this morning’s blog post, John D. Cook talks about poker hands and their probabilities. In particular, he says | Continue reading
I drove down to Vincennes, Indiana, yesterday to see the eclipse, and everything was just about perfect—some through planning and some through serendipity. Here’s a brief review. | Continue reading
As promised last time, we’ll now work out the solution for this three-span continuous beam with a uniform distributed load. | Continue reading
I thought I’d run through how the moment diagrams in the last post were made. It’ll probably take two articles to get through it all. | Continue reading
I don’t have anything particularly insightful to say about the collapse last week of the Francis Scott Key Bridge in Baltimore. But while reading some of the early reports on the collapse, I noticed two seemingly contradictory comments on the role of structural continuity in the … | Continue reading
I assume that most of you have already listened—at least in part—to the latest episode of Upgrade, the 40th Anniversary of the Mac Draft. Any podcast with both John Gruber and John Siracusa is going be longer than your average Upgrade; I’m impressed they brought it in at 2½ hours … | Continue reading
My last post ended with this graph: | Continue reading
Rhett Allain, who’s the physics columnist for Wired and a professor of physics at Southeast Louisiana State University, solved a funny problem a couple of weeks ago involving a ladder leaning against a wall. You can see his solution on YouTube or Medium. I think of it as an oddba … | Continue reading
Julia Evans has been posting on Mastodon recently about the GNU Project’s insistence on documenting its commands through info pages instead of man pages and (the following may be biased by my own thoughts) how absolutely awful that is. The posts reminded me that although I wrote … | Continue reading
Wolfram touts its Knowledgebase as “the world’s largest and broadest repository of computable knowledge” and “carefully curated expert knowledge directly derived from primary sources.” There’s certainly a lot in there, but there are some inexplicable holes that could be filled wi … | Continue reading
Tuesday morning, which was November 28, John D. Cook started a post with | Continue reading
Here are some little tricks associated with Wordle and Conlextions, the Connections-like puzzle put out by Lex Friedman. | Continue reading
Last week I solved Wordle in a single guess. My go-to first guess, IRATE, finally came in after months (over a year, I think) of use. So what do I do now? Seems like a good time to switch my starting guess. | Continue reading
Earlier today, I talked about sticking with a problem longer than I probably should because I can’t stop. Let’s apply that pathology to the Taskmaster coin flip subtask and think about a slightly different problem.1 Suppose we flip a fair coin and stop when we’ve flipped either f … | Continue reading
I recently did that thing we’ve all done, where I kept working on a problem, refining the solution far beyond its value. I don’t think it’s necessarily wrong to overwork a problem—I always learn from the experience, and the reason I keep at it is that I’m having fun making the li … | Continue reading
In the latest episode of Taskmaster, of which Channel 4 has posted a sneak peek, there’s a subtask related to my last post on Markov chains. The contestants are required to flip a coin and get five consecutive heads before moving on to the next part of the task. As you might expe … | Continue reading
This week’s Numberphile video features the BBC’s favorite mathematician, Marcus du Sautoy, who explains how the game Snakes and Ladders1 is governed by the mathematics of Markov chains. Despite some experience analyzing Markov chains in grad school, I had trouble understanding on … | Continue reading
Writing about how I work leads me to think about improvements I can make, which I then want to write about, leading me to think about making further improvements, and so on. So it was with my recent “one notebook” post. The last paragraph included this ominous sentence: | Continue reading
Science writer Jennifer Ouillette linked to this Scientific American article on Mastodon this morning. It’s about happy and sad numbers, which I had never heard of before. The article is by Manon Bischof, and was originally published in Spektrum der Wissenschaft, where she’s an e … | Continue reading
Recently, Brad Dowdy—you know, The Pen Addict— ran a poll on Mastodon, asking how many different notebooks people use. | Continue reading
A couple of days ago, Matt Parker posted this video about antiprisms. | Continue reading
Many years ago, I wrote about how many Friday the 13ths you can have in a year. At some point in the intervening decade, I read that the 13th of the month occurs more often on Friday than any other weekday, but I never checked up on it. This morning I did. | Continue reading
Yesterday, longtime friend of the blog Nathan Grigg posted this on Mastodon: | Continue reading
I’ve been thinking a lot about the NY Times Connections game lately, mainly because my family keeps playing it wrong. They’d get mad at me if I told them that, so I’m telling you. | Continue reading
Generally speaking, I dislike writing shell scripts. The operators are cryptic (yes, I’ve enjoyed writing Perl), whitespace matters way more than it should (yes, I’ve enjoyed writing Python), and I just always feel I’m one step away from disaster. A lot of my scripts start out as … | Continue reading
A couple of days ago, I wrote a post that included this image: | Continue reading
As I mentioned on Mastodon yesterday, I expect to be be including more equations in future posts, and I’d like the equations to appear readable in my RSS feed. This is a test to see if MathML will work. | Continue reading
During yesterday’s keynote, I learned some things about the switch from stainless steel to titanium in the iPhone 15 Pro that I’d been guessing about before. I also did some quick and dirty calculations that might explain why Jason Snell thought the 15 Pro seemed distinctly light … | Continue reading
John Cook posted a fun article today about the all the possible football scores. The key is to recognize that a team’s score can be any non-negative integer other than one.1 If the most points a team can score is M, then Cook’s reasoning is | Continue reading
This afternoon, there will be a hearing in the Georgia state court case against Donald Trump and his 18 co-defendants. Judge Scott McAfee ordered the hearing yesterday and asked DA Fanni Willis’s office to make | Continue reading
Last week, John D. Cook wrote an article that I kind of agree with and kind of disagree with. Weirdly, I think he kind of disagrees with it, too. | Continue reading
Earlier this year, I had some trouble publishing one of my posts. I think it was this one, and the problem was caused by the parentheses in the title. The code I’d written long ago to turn a title into the slug used in the URL wasn’t as robust as I thought it was. At the time, I … | Continue reading
For a long time, I’ve been using ImageOptim to reduce the size of PNG files I use here on the blog. The SnapClip and SnapSCP macros I use for taking most of my screenshots run ImageOptim automatically, but when I need to annotate or otherwise edit a screenshot, I have to run Imag … | Continue reading
A couple of days ago, Numberphile posted another Tom Crawford video in which he presents an interesting problem and explains it in an unnecessarily complicated way. This time, it’s the Sleeping Beauty problem. | Continue reading
My last post ends with “one last thing” about continued fractions. That turned out to be a lie. After playing around a bit more, I decided I should have some functions that compute continued fractions in Python, so I looked around for continued fraction libraries. I found some, b … | Continue reading
A few days ago, Rhett Allain, professor of physics education at Southeastern Louisana University and Wired columnist, posted a video in which he wrote a short Python script that used mediants to convert real numbers into fractions. I thought it was worth a few comments. | Continue reading
For the past few weeks, my family has been playing a new (it’s in “beta”) New York Times game called Connections. Our daughter found it—she has an NYT games subscription—and got the rest of the family hooked on it. | Continue reading
Back in March, my doctor prescribed a new pill for me to take every day. That brought the number up to six—five in the morning and one at night—and I decided to give the medication tracking feature of the iOS Health app a try. This was a new addition last fall when iOS 16 came ou … | Continue reading
A couple of days ago, as I was out taking my morning walk, I passed a guy on a bicycle who was coming the opposite way down the path. I was northbound, he was southbound. He was, annoyingly, playing his music out loud through a speaker instead of privately through earbuds. Less a … | Continue reading
Sometimes I realize I’ve been doing something the slow way for a really long time, and it’s kind of embarrassing. A few days ago, I needed to take a column of numbers from a spreadsheet and convert it into a comma-separated list for pasting into Mathematica. I pasted the numbers … | Continue reading