## My Things for Pi Day

I regret not having the time or energy to write something original about π for today. I hope you’ll accept this offering of past Reading the Comics posts covering the day, and some of my other π-related writings:

For the Pi Day Of The Century (3/14/15) I wrote Calculating Pi Terribly. It’s about a legitimate way to calculate the digits of π, using so very much work that nobody will ever do it. But the wonderful thing about it is it’s experimental. And it doesn’t involve something with an obvious circle. A couple months later I followed up with Calculating Pi Less Terribly, using one of the most famous numerical methods for calculating the digits of π. It’s still not that good, but it’s far better than the experimental approach.

In 2019, as part of that year’s A-to-Z, I wrote more extensively about Buffon’s Needle problem, the core of this experimental method for finding digits of π.

And then there’s comic strips. I seem to complain every year that there’s fewer Pi Day comic strips than I expected, which invites the question of just what I expect. Here’s, as best I can tell, the actual record:

I have not yet read today’s comics, so don’t know what they’ll offer. We shall see! Also, I apologize but some of the comics may have been removed from GoComics or Comics Kingdom, and so the links may be dead. I’m not happy about that. But if I wanted the essays discussing these strips to stay permanently sensible I’d have posted the comics on my own web site.

And one last thing, bringing up an essay I’ve shared before. The End 2016 Mathematics A To Z: Normal Numbers is … maybe … about π. Nobody knows whether π is a normal number. It most likely is, but we haven’t been able to prove it.

And the last thing. When I thought I would have time this March, I hoped to write something about how π can be defined starting from differential equations. Things changed my plans out from under me. But my 2020 A-to-Z essay on the Exponential gets at some of why π should turn up in the correct differential equation. That essay sets you up more to understand a famous equation, that $e^{\pi \imath} + 1 = 0$. But it’s not too far to getting π out of solving $y''(t) = -y(t)$ in the right circumstances. I may get to writing that one yet.

## Calculating Pi Terribly

I’m not really a fan of Pi Day. I’m not fond of the 3/14 format for writing dates to start with — it feels intolerably ambiguous to me for the first third of the month — and it requires reading the / as a . to make sense, when that just is not how the slash works. To use the / in any of its normal forms then Pi Day should be the 22nd of July, but that’s incompatible with the normal American date-writing conventions and leaves a day that’s nominally a promotion of the idea that “mathematics is cool” in the middle of summer vacation. This particular objection evaporates if you use . as the separator between month and day, but I don’t like that either, since it uses something indistinguishable from a decimal point as something which is not any kind of decimal point.

Also it encourages people to post a lot of pictures of pies, and make jokes about pies, and that’s really not a good pun. It plays on the coincidence of sounds without having any of the kind of ambiguity or contrast between or insight into concepts that normally make for the strongest puns, and it hasn’t even got the spontaneity of being something that just came up in conversation. We could use better jokes is my point.

But I don’t want to be relentlessly down about what’s essentially a bit of whimsy. (Although, also, dropping the ’20’ from 2015 so as to make this the Pi Day Of The Century? Tom Servo has a little song about that sort of thing.) So, here’s a neat and spectacularly inefficient way to generate the value of pi, that doesn’t superficially rely on anything to do with circles or diameters, and that’s probability-based. The wonderful randomness of the universe can give us a very specific and definite bit of information.