I was working in my living room.  My computer was upstairs, but I had my phone and tablet.  I'm working on The Book ("Perturbation methods using backward error", with Nic Fillion, which will be published by SIAM next year some time).

I've discovered something quite cool, historically, about the WKB method and George Green's original invention of the idea (that bears other people's names, or, well, initials, anyway).  (As usual.)  Green had written down a PDE modelling waves in a long narrow canal of slowly varying breadth 2*beta(x) and slowly varying depth 2*gamma(x).  Turns out his "approximate" solution is actually an exact solution to an equation of a very similar kind, with an extra term E(x)*phi(x,t).  The extra term depends in a funny way on beta(x) and gamma(x), and only on those.  So a natural kind of question is, "is there a canal shape for which Green's solution is the exact solution with E(x)==0?"  Can we find beta(x) and gamma(x) for which this works?

Yes.  Lots of cases.  In particular, if the breadth beta(x) is constant, you can write down a differential equation for gamma(x).  I wrote it in my notebook using y and not gamma.  I wrote it pretty neatly.  Then I fired up the Maple Calculator on my little tablet, opened the camera, and pow!  Solved.

I wrote the solution down underneath the equation.  It checks out, too.  See the attached image.

Now, after the fact, I figured out how to solve it myself (using Ricatti's trick: put y' = v, then y'' = v*dv/dy, and the resulting first order equation is separable).  But that whole "take a picture of the equation and write down the solution" thing is pretty impressive.

So: kudos to the designers and implementers of the Maple Calculator.  Three cheers!

Maple Transactions has just published the Autumn 2024 issue at mapletransactions.org

From the header:

This Autumn Issue contains a "Puzzles" section, with some recherché questions, which we hope you will find to be fun to think about.  The Borwein integral (not the Borwein integral of XKCD fame, another one) set out in that section is, so far as we know, open: we "know" the value of the integral because how could the identity be true for thousands of digits but yet not be really true? Even if there is no proof.  But, Jon and Peter Borwein had this wonderful paper on Strange Series and High Precision Fraud showing examples of just that kind of trickery.  So, we don't know.  Maybe you will be the one to prove it! (Or prove it false.)

We also have some historical papers (one by a student, discussing the work of his great grandfather), and another paper describing what I think is a fun use of Maple not only to compute integrals (and to compute them very rapidly) but which actually required us to make an improvement to a well-known tool in asymptotic evaluation of integrals, namely Watson's Lemma, just to explain why Maple is so successful here.

Finally, we have an important paper on rational interpolation, which tells you how to deal well with interpolation points that are not so well distributed.

Enjoy the issue, and keep your contributions coming.

The Proceedings of the Maple Conference 2023 is now out, at

mapletransactions.org

The presentations these are based on (and more) can be found at https://www.maplesoft.com/mapleconference/2023/full-program.aspx#schedule .

There are several math research papers using Maple, an application paper by an undergraduate student, an engineering application paper, and an interesting geometry teaching paper.

Please have a look, and don't forget to register for the Maple Conference 2024.

Maple Transactions frequently gets submissions that contain Maple code.  The papers (or videos, or Maple documents, or Jupyter notebooks) that we get are, if the author wants a refereed submission, sent to referees by a fairly usual academic process.  We look for well-written papers on topics of interest to the Maple community.

But we could use some help in reviewing code, for some of the submissions.  Usually the snippets are short, but sometimes the packages involved are more substantial.

If you would be interested in having your name on the list of potential code reviewers, please email me (or Paulina Chin, or Jürgen Gerhard) and we will gratefully add you.  You might not get called on immediately---it depends on what we have in the queue.

Thank you very much, in advance, for sharing your expertise.

Rob

My friend and colleague Nic Fillion and I are writing another book, this one on perturbation methods using backward error analysis (and Maple).  We have decided to make the supporting materials available by means of Jupyter notebooks with a Maple kernel (there are some Maple worksheets and workbooks already, but going forward we will use Jupyter).

The presentation style is meant to aid reproducibility, and to allow others to solve related problems by changing the scripts as needed.

The first one is up at 

https://github.com/rcorless/Perturbation-Methods-in-Maple

Comments very welcome.  This particular method is a bit advanced in theory (but it's very simple in practice, for weakly nonlinear oscillators).  I haven't coded for efficiency and there may be some improvements possible ("may" he says, sheesh).  Comments on that are also welcome.

-r