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A First Course in Differential Equations for Scientists and Engineers

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Re: A First Course in Differential Equations for Scientists and Engineers

#41

While the linked course seems a lot more thorough, I took the Udacity "Differential Equations in Action" [1] course, which I found very well done. For the homework you write Python programs to compute things like gravitational slingshots, modeling epidemics, wildfires, and the n-body problem. [1] https://www.udacity.com/course/differential-equations-in-act...

Can we get to the text and videos without all the school-ish crud? (starting a course, timelines etc.)

Re: A First Course in Differential Equations for Scientists and Engineers

#42
post #32
post #27

Earlier quoted context omitted.

With calculus, you are already well into ordinary differential equations -- partial differential equations are different, but with calculus you have a good start on the basics of those, too. A simple ordinary differential equation is below where of course just from calculus y'(t) = d/dt y(t) and the equation is y'(t) = k y(t) ( b - y(t)) So, for the context: t is time, say, in seconds. y is some real valued function…

> I looked through it, saw lots of intricate stuff, but wondered just why I should dig into that. Since then I read a story about Rota about how, apparently, he felt much the same about the material Ah yes, the classic rant by Rota. Entertaining read, and good perspective (10 pages). Apparently written in 1997. https://web.williams.edu/Mathematics/lg5/Rota.pdf

Btw, the third formula on p. 9 is slightly wrong. Don't anyone lose your sleep over it.

Re: A First Course in Differential Equations for Scientists and Engineers

#44

On a related note, how do you take notes for math subjects with their multiline integrals and sumation and subscripts, division etc? I'm very much attached to recording every thing in simple text editors. Is there a "Notepad" or "TextEdit" for mathematical notation?

Do not deprive yourself of the delight of browsing through your handwritten notes some years in the future!

Re: A First Course in Differential Equations for Scientists and Engineers

#45
post #7

Look at Arnold's book on Diff, it is harder then others, but has absolutely different outlook.

That book is totally mindblowing, and obliterates artificial boundaries between physics and mathematics. It also (in the older Dover editions) had a cover where the phase portrait on the front looked like two angry eyes glaring at you that you hadn't learned enough math yet.

Well, modern theoretical physics seems to be nothing but mathematics (mostly advanced differential geometry and group theory). And this is a good thing, as it is the sign of how far along the subject has gone in its evolution. The theory of differential equations also reduces to differential geometry, which is what Arnold’s book seems to be striving to show, as does his other excellent text on mathematical principles of classical mechanics.

Re: A First Course in Differential Equations for Scientists and Engineers

#46
post #4

Lately I have been looking for a practical (not too much theory) book on how to model problems with differential equations, with lots of examples. I imagine I'd plug them into Wolfram Alpha to get a solution. Does anyone have recommendations?

You can also look into "system dynamics" software, which allows for the modeling of complex systems with very little user-facing mathematics. Dana Meadows wrote a book called "Thinking in Systems," which is a great intro to this subject.¹

I personally have used Stella by isee systems, which will output an equation from your model if you are so inclined, but I think there is cheaper/free software out there that will do similar types of modeling.

1. https://wtf.tw/ref/meadows.pdf

Re: A First Course in Differential Equations for Scientists and Engineers

#47
post #43

Speaking of differential equations, an oldie (1997) but goodie, "Ten Lessons I Wish I Had Learned Before I Started Teaching Differential Equations" by Gian-Carlo Rota: https://web.williams.edu/Mathematics/lg5/Rota.pdf

> 4. Teach Changes of Variables

As someone who has basically no formal training in mathematics outside what's required for undergraduate computer science this is a big one. The first time I saw it I was blown away. Everyone who knows of it seems to treat it as natural as breathing, and not worth the exposition

Re: A First Course in Differential Equations for Scientists and Engineers

#49

While the linked course seems a lot more thorough, I took the Udacity "Differential Equations in Action" [1] course, which I found very well done. For the homework you write Python programs to compute things like gravitational slingshots, modeling epidemics, wildfires, and the n-body problem. [1] https://www.udacity.com/course/differential-equations-in-act...

I took the first part of that course, enough to write an n-body game:

https://github.com/madengr/nbody

While it was a good course, I wish it covered the analytic portion, rather than dive straight into numerical solutions.

Re: A First Course in Differential Equations for Scientists and Engineers

#50
post #39

Earlier quoted context omitted.

Those useless transforms (are you referring to Laplace and friends?) are pretty useful in EE.

Yep, the transforms and series solutions are actually the most important part of ODEs, not just in EE but also in PDEs.

All fair criticisms, but I was recollecting on reading Boyce & DiPrima where the Laplace was relegated to IVP.

I was left with feeling that I had only learned yet another trick until I read Churchill & Brown's Complex Variables and Applications.

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