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Mail Archives: djgpp/1998/03/19/13:31:24

From: NOSPAMsl AT psycode DOT com (Gili)
Newsgroups: nctu.club.astronomy,relcom.fido.su.astronomy,sl AT psycode DOT com,comp.os.msdos.djgpp,gac.physics.astronomy
Subject: Re: Orbits, planets, PLEASE HELP!
Date: 19 Mar 1998 18:06:48 GMT
Organization: Generation.NET
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References: <bWLoegW7sFse-pn2-nOBQTFs4XI88 AT portA01 DOT Generation DOT NET> <350DFA18 DOT DF98FAE5 AT mail DOT coos DOT or DOT us>
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On Tue, 17 Mar 1998 04:20:40, Jason Dagit <thedagit AT mail DOT coos DOT or DOT us> 
wrote:

> Hello,
> 
> Here is how I would tackle this dilema:
> 
> Perhaps I'm just ignorant (I'm 18 and still in HS) but wouldn't it be
> possible to find the paths of the celestial objects simply by applying
> the forces of gravity in 3 dimensions?  I mean, you can find out the
> masses, you know the formula for gravity (or at least it should be easy
> to find) and if you can find the velocities and distances you're set. 
> Of course this would be a very slow and time consuming process to
> calculate the gravity equation for all the celestial objects every
> second.  One optimization would be to consider the ratio of masses and
> what the force of gravity was before the distance changed then use that
> to find the new force of gravity given a change in distance.  Also, I
> think to get the right answers you would need to keep all the original
> information until you have processed all the celestial objects, then
> write over that old data with the new.  Perhaps you could store all the
> changes in force in a transition matrix and then use that.  I'm not sure
> about the best/fastest implementation.
> 
> One forseeable (is that a word?!?) problem is that your data types won't
> give enough precision.  Arbitrary math libs are out there, but they are
> slower than intrinsic data types.
> 
> Before anyone calls me dumb for doing it this way, let me say, I've only
> had one year of physics and no one else has suggested a way in this ng.

	Actually, that's EXACTLY the way I'm doing it. It's working, kinda, 
so far... Umm, what did you mean about my variable types leading to 
error?

Gili

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