Celestia Forums

Here's a potential resource for integrating motions of objects in planetary systems, for possible future use with Celestia.

It may be applicable to close planetary flybys, double and multiple star systems (including hypothetical planets), etc.

It is evidently written in Fortran and would have to be converted to C.

The URL is

http://www.boulder.swri.edu/~hal/swift.html

- Hank


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SWIFT

A solar system integration software package

The SWIFT subroutine package written by Hal Levison and Martin Duncan is designed to integrate a set of mutually gravitationally interacting bodies together with a group of test particles which feel the gravitational influence of the massive bodies but do not affect each other or the massive bodies. Four integration techniques are included:

Wisdom-Holman Mapping[1] (WHM). This algorithm was created by Jack Wisdom & Matt Holman.

Regularized Mixed Variable Symplectic (RMVS) method. This handles close approachs between test particles and planets. This algorithm was created by Hal Levison & Martin Duncan and based on WHM.

A fourth order T+U Symplectic (TU4) method. This algorithm was created by Jeff Candy and W. Rozmus. Also see Martin Duncan, Brett Gladman, and Jeff Candy.

A Bulirsch-Stoer method.

The package is designed so that the calls to each of these look identical so that it is trivial to replace one with another.

We know that SWIFT will run on HP9000s, SUNs, MIPS, IBM RS6000, DEC alphas (UNIX and Linux), PC's (Linux) and DECstations. If you are going to run SWIFT on a machine not listed, please let us know how it works.

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Hello Hank,

Did you ever work with this SWIFT program? Well I am trying to run it on my computer and I'm having problems. Do you think you could kindly help me with a few questions?

Cheers-Leila

Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

The information about SWIFT seems to have been copied from its home page.
I suggest you contact its authors at SWRI for help.

ElChristou wrote:Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

I always thought that Chris L. has nominated him as his "deputy" quite a while ago

Fridger

t00fri wrote:

ElChristou wrote:Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

I always thought that Chris L. has nominated him as his "deputy" quite a while ago

Don't be such a bad boy!

ElChristou wrote:

t00fri wrote:

ElChristou wrote:Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

I always thought that Chris L. has nominated him as his "deputy" quite a while ago

Don't be such a bad boy!

Why, I am always sticking to the facts Here is the reference:

Chris wrote:

hank wrote:It might be a good idea to have a backup admin for the Celestia project at Sourceforge in any case.

Agreed. It's an essential part of making Celestia development less bottlenecked by me (though I have no plans to leave the project). Would you be up for it, Hank? I note that you're also in Seattle--the geographical concentration of Celestia project admins could be a liability should an errant asteroid come our way Perhaps we need a third person, ideally someone on another continent.

--Chris

Fridger

t00fri wrote:

ElChristou wrote:Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

I always thought that Chris L. has nominated him as his "deputy" quite a while ago

You have two choices, Fridger:
- You can stop ridiculing other Celestia contributors,
- Or, you can retire immediately from the project.

I appreciate your contributions, but I've had enough of this.

--Chris

chris wrote:

t00fri wrote:

ElChristou wrote:Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

I always thought that Chris L. has nominated him as his "deputy" quite a while ago

You have two choices, Fridger:
- You can stop ridiculing other Celestia contributors,
- Or, you can retire immediately from the project.

I appreciate your contributions, but I've had enough of this.

--Chris

What a choice!

After 7 years of collaboration, I take the latter option, of course...

Fridger

Guys, let's return to adult age please!

Anyway Chris, not that I want to side with Fridger on this one, but when someone begins stuff and then disappear from the day to the other, I guess a bit of irony is not thaaat misplaced...

Perhaps Hank had serious reasons to disappear, but a correct person would have post a note to inform the rest of the community... ...Strangely, that remind me your long absences without any advance notice some years ago driving people crazy... Would that be some kind of practice from Seattle? (kidding of course)

Last thing, just wanted to know, before giving Fridger 2 options, have you ask the rest of the dev team about this kind of injunction? Is there a consensus to treat such an important contributor this way?

Ok, I guess better I calm down else I will be also out...

ElChristou wrote: Last thing, just wanted to know, before giving Fridger 2 options, have you ask the rest of the dev team about this kind of injunction? Is there a consensus to treat such an important contributor this way?

Ok, I guess better I calm down else I will be also out...

No danger of that.

If you want to discuss this with me, send me a PM or email me. I don't want invite a nasty, prolonged flame war in this thread.

--Chris

chris wrote:...If you want to discuss this with me, send me a PM or email me. I don't want invite a nasty, prolonged flame war in this thread.

Sorry Chris, won't PM or email you because 1) I consider this to be VERY relevant for the community and the future of Celestia so I guess people deserve to know all the details of the problem, 2) In general it's not in my habit to talk in people's back; I'm not comfortable with this and prefer by far public explanations (this way one do have to weight his words...)

Anyway, from what I saw during these years, all problems with Fridger came from the fact that many people take their hobby for religion. The problem even is one have knowledge and is good at something, is that he should be careful in front of a professional. Each time a flame war begin, was because someone believe he knew something better than others. Each time Fridger was involved, he proved to be right. People want to leave because they have taken offense when they were wrong? Fine, good for them! If between what's best for the project and their pride, they chose their pride, then they are better FARRR away.

If this project was structured correctly with people clearly responsible of each branch (engine, UI, textures, databases, documents, etc...) thing would be different. That something I've been saying for years, and still don't understand why it's such a problem fro you guys to structure this project more seriously... (and please, I don't want to heard the song about the good old Celestia family where everybody is happy sharing all the stuff because clearly over years there is no much left of the family...)

chris wrote:...I don't want invite a nasty, prolonged flame war in this thread.

BTW, it's a 2002 thread, so nothing like a flame war to keep it at the sight of the public!

Just a quick note from the Brain-Dead here...

I am also prone to the "disappearing act" mentioned earlier in this thread.
I apologize for this, but it is what it is. My health, on occasion, forces me
to the hospital, and there is nothing I can do about that.

On the other hand, if I disappeared for 4 years or so, I would certainly
expect that the community should forget about me.

On the current topic concerning the "retirement" of Dr. Schrempp
from this community, I believe that this would be a terrible mistake.
Obviously, the Good Doctor needs to enhance his people skills, but
his undying efforts to improve Celestia are worth his occasional lack
of "people skills." Hee, hee...

Just my two cents worth.

Thanks, Brain-Dead

BobHegwood wrote:Just a quick note from the Brain-Dead here...

I am also prone to the "disappearing act" mentioned earlier in this thread.
I apologize for this, but it is what it is. My health, on occasion, forces me
to the hospital, and there is nothing I can do about that.

Bob, of course there is some extreme cases, but that is not the norm. Nowadays, because of "virtualization" of the society, people tend to not care anymore about the most simple and essential attentions they should offer to their correspondent. Saying a word (even a insult) don't cost much but show that you consider the guys at the other end of the line. I don't know you, I find quite insulting someone who abandon an open process (can be a simple discussion, or a real work) without leaving any traces...

BobHegwood wrote:On the current topic concerning the "retirement" of Dr. Schrempp
from this community, I believe that this would be a terrible mistake.

Of course it would be... and a big one...

BobHegwood wrote:Obviously, the Good Doctor needs to enhance his people skills, but
his undying efforts to improve Celestia are worth his occasional lack
of "people skills."

If only that was the real problem...

chris wrote:

t00fri wrote:

ElChristou wrote:Hi, Leila, not sure you saw the date of Hank's post; 2002... There is quite some time we don't see him on the board, so don't be surprise if you don't get any response. Anyway who knows...
Good luck!

I always thought that Chris L. has nominated him as his "deputy" quite a while ago

You have two choices, Fridger:
- You can stop ridiculing other Celestia contributors,
- Or, you can retire immediately from the project.

I?m sorry, i don?t see ridicule here. I see a joke. There is a smiley on it to tip you off, even.
Am i missing something?

- rthorvald

Unfortunately, what may be seen as a joke by others is often interpreted quite differently by the people directly involved.

selden wrote:Unfortunately, what may be seen as a joke by others is often interpreted quite differently by the people directly involved.

Yes, i know. But that is why we use emoticons - it?s what they are for

- rthorvald

What is funny (or perhaps makes want to cry) is how interested are people in this community... Perhaps it's really the sign we should all go for something else...

ElChristou wrote:What is funny (or perhaps makes want to cry) is how interested are people in this community... Perhaps it's really the sign we should all go for something else...

The release of your ISS model may change this !