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Message started by Mal on 08/19/07 at 17:22:03

Title: The Disturbing Function?
Post by Mal on 08/19/07 at 17:22:03

I'm guessing that several folks here have Murray and Dermott's Solar System Dynamics book... I'm just wondering if anyone understands how the Disturbing Function that is described in it works. I've never been able to get my head around it at all.

Title: Re: The Disturbing Function?
Post by Tony on 08/20/07 at 17:03:24

13 views and no replies.  That's disturbing  :o

I wish I could help you, but there's a reason I prefer numerical methods  ;)

Title: Re: The Disturbing Function?
Post by Mal on 08/20/07 at 17:32:31

Yeah, I was kinda hoping that people here of all places might have some clue how to use it... but I guess you guys find out stuff by directly modelling it ;)

It's really dense stuff, full of series expansions, but section 6.7 in the book (p248) is about "Use of the Disturbing Function". It gives 9 steps for how to use it, but I'm blowed if I can even understand how to figure out the first step - it helpfully says "Decide which combination of angles is applicable to the problem at hand", and then points you to section 6.9 to figure that out... which is similarly incomprehensible.

I'm sure it's useful somehow, but it's way over my head. And I did the course that the book was based on while at QMW and didn't understand it then either! :(

Title: Re: The Disturbing Function?
Post by Tony on 08/20/07 at 21:11:03


Mal wrote:
... but I guess you guys find out stuff by directly modelling it ;)

Us guys?  Don't try to distance yourself from us with your 181 posts.  It's too late.  You're one of us now.  ;D

If it makes you feel any better, next year I may take a course at UC Berkeley by Eugene Chiang.  Solar System Dynamics is the textbook for the course.  I just need to take Calc III first so I don't get too lost.

When I look at my copy of the book, it's beat up, wrinkled, it looks like I took it camping for a year and slept with it.  It's one of my favorite books ever, which is kinda strange considering I understand about 10% of it.

But it's fun using Gravity Simulator to recreate some of the things they talk about.  Recreating the concepts without understanding the math can be gratifying.

Title: Re: The Disturbing Function?
Post by Mal on 08/20/07 at 21:28:02

Hehe, same here really. My book's not so much bashed up as full of scribbled notes and bookmarks! My understanding goes as far as understanding the two-body stuff, and the tidal stuff. Everything else goes over my head, though I can get some of it qualitatively at least. Didn't help that I did the MSc that the SSD course was part of (taught by Carl Murray, incidentally) with absolutely no relevant maths background beyond 1st year university maths (basic calculus was about all I could handle) - all that series expansion and vector calculus went waaaay over my head. Still, it is one of my most referred to text-books :).

And I'm really nowhere in the league of you and Frank when it comes to playing with GravSim. I don't even understand half the stuff that Frank comes up with, all I know is that it makes pretty patterns! I just use gravity simulator to test out the systems I make for Traveller :)

Title: Re: The Disturbing Function?
Post by frankuitaalst on 08/21/07 at 08:51:10

[quote author=Mal link=1187569323/0#4 date=1187670482] I don't even understand half the stuff that Frank comes up with....quote]
I think I have to have a course in English I guess .  :-[
By the way : I don't know/have the book but it seems to be interesting . Is it possible to provide me with a legal copy of the pages mentionned above ?

Title: Re: The Disturbing Function?
Post by Mal on 08/21/07 at 20:51:11


frankuitaalst wrote:
I think I have to have a course in English I guess .  :-[/quote]

Oh, your english is fine, that's not what I have trouble understanding :). It's just that I look at your amazing animations and don't have a clue what I'm looking at! ;)

[quote]By the way : I don't know/have the book but it seems to be interesting . Is it possible to provide me with a legal copy of the pages mentionned above ?


You're in Germany, aren't you? You can find it on amazon.de (http://www.amazon.de/Solar-System-Dynamics-Carl-Murray/dp/0521575974/ref=sr_1_12/028-5462556-3284515?ie=UTF8&s=books-intl-de&qid=1187754610&sr=8-12)

EDIT: oops, never mind, you're in belgium. Still, amazon.de is probably the most european Amazon isn't it?

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