It’s been another slow week.

As I said, my alter ego the kid had picked up a recent textbook on seismology… and now I’m looking at continuum mechanics again. Although the impetus is the modeling of solids, I refuse to specialize yet, so I’m still looking at continua in general.

And I am beginning to understand the distinction between the Eulerian and Lagrangian points of view. I need to play with this some more. 13 months ago, I posted some links to videos about the 2 points of view.

Speaking of seismology, there were 3 earthquakes within 100 miles of me during the past week – all were between 2.6 and 2.7 in magnitude. So earthquakes that small are nowhere near as frequent as I expected, at least not in my “immediate” vicinity.

My alter ego Jimmie – who is responsible for 6 major subjects! – has picked up control theory. As a result, I have begun running Mathematica® version 8… it occurs to me that I have an update as yet uninstalled. (I have to alter the menu so that command-U gets me underlined text.)

Oh, I own “Control System Professional”, which was fine for earlier versions of Mathematica, but version 8 includes functions for control theory – and some things look better – so I’d rather use version 8 than the add-on and version 7. Apart from control theory, however, I’m still running version 7. As I keep saying, I do not even want to know what version 8 broke in my version 7 notebooks.

Jimmie is also responsible for time series analysis – that is, right now, regression – and he has my final post – at last! – ready for multicollinearity. He needs to start working on the next regression post – which will begin talking about the fundamental assumptions we make when we analyze regressions, and how they get us the usual statistical treatment of our results.

It would also be nice if he would finish off the calculations for the Higgs particle. I’ve gotten the simple illustration of spontaneous symmetry breaking… and I’ve gotten the massless Goldstone boson… but not a Higgs particle. But with the lecture about it behind me, all the urgency is gone.

My alter ego the undergraduate is done with trusses. He hasn’t decided what he’s doing next. Maybe, in fact, he’s the one already doing continuum mechanics.

My alter ego the graduate student is still working on rings… the failure of unique factorization, to be specific… but he has begun writing an introduction. For some reason – actually, simply because I am less comfortable with rings than with groups – it looks like this introduction will be a bit more formal than, for example, my introduction to groups.

So… a little regression, continuum mechanics, control theory, rings, and particle physics. That might keep me out of trouble this weekend.

But first, let’s see what my alter ego the kid wants to play with. There could be trouble.

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