The Three Alternative Branches of Government

Parabolic, Elliptic, and Hyperbolic.

Fun Fact: The "Hyperbolic Branch" of government has plenty of shocks. :)

Bonus (for devotees of complex variables): Transcendental, Logarithmic, and Principal https://t.co/wly6LdMXBn

— Mason Porter (@masonporter) December 22, 2019

Introduction to "Confusion Equations"

Proposal: "Convection–Diffusion Equations" should be called "Confusion Equations" (or at least "Conffusion Equations").

John Nash and Louis Nirenberg Share 2015 Abel Prize

John Nash and Louis Nirenberg have been jointly awarded the 2015 Abel Prize for their work on partial differential equations.

(Tip of the cap to Physics Today for their post on Facebook.)

Laplace's Equation: The Game

Thanks to my Somerville undergraduates for the very nice gift and card that they brought to today's leavers party. (The game is called Squint.)

Seminar of the Week

One of the Mathematical Institute's seminars next week is the following:


Monday 13th Feb
*Partial Differential Equations Seminar
17.00 Gibson 1st Floor SR
The problem of wedge entry
Bryce McLeod (OxPDE)



Maybe it's just me, but I'm not so sure how keen I am to hear an old British guy discussing "wedge entry"...

Fun with Equation Names

I looked at a very interesting paper today (that I need to read carefully) that refers to a paper called the "modified MKdV" equation, which is called the MMKdV equation for short. Let's unpack this name:

The KdV equation stands for the Korteweg-de Vries equation. In other words, it's named after two people.

The MKdV equation stands for the "modified KdV" equation, which means that the MMKdV is in fact the "modified modified KdV" equation, which I would prefer to called the (modified)^2 KdV equation, although I'd really prefer a different adjective entirely be applied to KdV.

It's not close to as bad as "The Los Angeles Angels of Anaheim" (which means "The The Angels Angels of Anaheim" or (The)^2 (Angels)^2 of Anaheim), but it's not exactly great. I have started to get a little bit of personal experience in how equation names arise. Namely, I wrote a paper and found myself in a paper constantly citing the book of a guy who formulated an equation that showed up in what we were doing, so my collaborators and I decided to name the bloody thing after the guy just so we wouldn't have to awkwardly cite the equation from his book so many damned times. He can thank us later.

Overheard in ACM 210a

In ACM 210a today, Professor Tom Hou said, "You don't want to jump the shock."

This is my quote of the day, and it will require some unraveling to convey the full significance.

First of all, it immediately made me think of the phrase jump the shark, an appreciation of which is required to fully enjoy the quote above. If you don't know what that phrase means -- and most of you should because I've discussed it on my blog before -- you owe it to yourself to take a look at the wikipedia entry on the other side of the link I provided.

The topic of the class is numerical methods for partial differential equations, and in the class of systems we're studying right now shocks are very common. When designing numerical schemes to deal with systems that can have this stuff, they typically have to be lower-order near the shock because if you're going to use nearby points for interpolation, you don't want points on both sides of the shock. That is, you don't want to jump the shock. Thus, Hou's comment (which was completely intentional) makes absolutely perfect sense scientifically. Moreover, he is as far as I can tell completely unaware of the term "jumping the shark," so it seems that he doesn't realize just how funny that comment is.

If I ever discuss the numerics of such systems in a talk, I am so going to use the picture of the Fonz jumping the shark on one of my slides. Maybe only one or two people in the audience will get the joke because it admittedly requires a reference leap, but it is bloody awesome!