Hi David,
So I don't have to re-invent the wheel, would you by chance know where such a
"library" for VB.NET might exist? My method is essentially brute force and
probably isn't all as accurate as it could be. However, like Jon mentions,
having an application that can generate where a planet is at various times
would be useful. Since what I'm working at would do that and then some, it
makes sense to try and find the EASY way first, then do it the hard way second.
Oddly enough, I did devise a method for determining distance based on hex ID -
but it was about 8 times larger than the source code I posted earlier in this
thread. Having someone else who knows what they are doing, and has posted the
algorithms for public use is far superior than anything I can cobble up. :)
Hal
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of David Scheidt
Sent: Tuesday, October 11, 2011 9:33 PM
To: The GURPSnet mailing list
Subject: Re: [gurps] Planetary movement example
On Tue, Oct 11, 2011 at 4:06 PM, Anthony Jackson <[email protected]> wrote:
> On 10/11/2011 5:34 AM, Captain Joy wrote:
>
>> No, but the angle a planet moves through given its current location
>> on the ellipse, semi major axis, delta-T, and eccentricity is an
>> equation that can be looked up.
>
> Actually, it isn't. There's no simple method of computing that, at least
> accurately when delta-T is a significant fraction of the orbital period.
Sure there are. There's no closed form, but there are iterative
methods that will produce a result with arbitrary accuracy. There are
libraries to do that in just about any reasonable programing language
(and some unreasonable ones, like Common Lisp and javascript.) you
would care to write a program in. Modern computation makes many hard
problems easy with a little bit of brute force. (Though Maple did a
fine job solving Kepler's equation via Newton's method when I was in
college, so it's not a problem that really requires a whole lot of
computational brute force.)
--
David Scheidt
[email protected]
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