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new beta version (Read 56945 times)
Tony
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new beta version
04/16/07 at 18:54:35
 
***  The most recent versions are at thebottom of this thread ***
 
I'm going to start making the beta versions public, as the beta is now far superior to the 2.0 version, and the new featuress seem to be quite stable.
 
This is the latest version.  It runs about 60% faster than the previous beta version, at least on my computer.  I'd be curious to know what results others get.
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta17Apr2007.exe
 
Download it into the same folder as your existing gravitysimulator.exe or your existing beta version and use it instead.
 
Future versions of the beta will include a contribution from frankuitaalst:  an Picard integrator.  So stay tuned...
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« Last Edit: 12/03/07 at 14:49:02 by Tony »  
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Re: new beta version
Reply #1 - 04/18/07 at 00:33:45
 
Yup. Runs much faster on my machine as well. Good job, Tony.
 
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Tony
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Re: new beta version
Reply #2 - 04/22/07 at 17:29:34
 
This one may be quicker yet, depending on how many objects are in your simulation.  Give it a try and let me know what you think.  Create a new folder for this one, and copy all 3 files into the folder:
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta22Apr2007.exe
http://orbitsimulator.com//gravity/beta/CodeOptomizer.dll
http://orbitsimulator.com//gravity/beta/resume.gsim
 
You can use any resume.gsim that you want.  It's just important that there is one in your folder.  This CodeOptomizer.dll is different than the one you have now.  It's the same code, just compiled more efficiently.  This is why I suggest you create a new folder.
 
And remember, this is a beta version, .so there may be bugs to be ironed out. And the new .dll may not work with all processors.  If you have trouble or successes, I'd love to know.
 
Richard "Publius", "Grav", and others from the Bad Astronomy forum are helping me with this one.  
http://www.bautforum.com/showthread.php?t=57336
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Re: new beta version
Reply #3 - 04/22/07 at 19:02:42
 

     Hi all. I'm "publius" that Tony mentioned above. I compiled the above version of the .dll using Intel's highly optimizing compiler. The version above requires a Pentium 4 or equivalent Athlon CPU with SSE2 instructions.  
 
         If your CPU doesn't have them, it will crash the program with an illegal instruction fault.  
 
         Second, we were trying to get some of the code to "vectorize" and made use of some static arrays. Just testing we hard coded 800 elements max. If a simulation uses more than 800 objects, then the .dll will crash with a buffer overrun.
 
           So just keep that in mind. It will not run on a PIII or earlier.  Once I get everything figured out, I'll try to compiler a PIII optimized version, and see if it does any better than the original code. But the SSE2 instructions really shine on large numbers of objects.
 
                                                                -Richard
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Re: new beta version
Reply #4 - 12/04/07 at 00:17:58
 
Download these into the same folder:
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta4Dec2007.exe
http://orbitsimulator.com//gravity/beta/CodeOptomizer.dll  
http://orbitsimulator.com//gravity/beta/resume.gsim
 
There are no huge changes.  But there's a new feature that lets you add a description to your simulations in the file menu.
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Re: new beta version
Reply #5 - 01/20/08 at 02:17:34
 
A bug in the new description feature is fixed
menu Objects > Create Objects now allows you to specify a Gaussian distribution.  However, my recent attempts to duplicate the odds predicted for asteroid 2007 WD5, when they were 1 in ~30 leave me wondering if I did this right.  I could only generate 1 hit for every ~300 objects, using JPL's figures and error bars, despite them claiming at the time that the odds were as low as ~1 in 30.
 
The rotating frame now allows you to stop plotting, without a new orientation being chosen for you when you begin plotting again.  (No one ever complained about this before, so you probably have no idea what I'm talking about Cheesy)
 
And one of the most reported bugs:  The x-position box in menu Objects > Edit Objects now works as advertised!
 
One small concern... The previous exe's for betas were twice the file size of this one.  And I didn't do anything different to reduce the file size.  I'm still in New Zealand, and working off of a system that I'm not quite familiar with, so that may explain the difference, but I'd appreciate any feedback just to make sure.
 
As usual, if you already have Gravity Simulator 2.0 installed on your system, simply download these files into the same folder, and use the beta exe instead:
 
 
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta20Jan2008.exe
http://orbitsimulator.com//gravity/beta/CodeOptomizer.dll  
http://orbitsimulator.com//gravity/beta/resume.gsim
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Re: new beta version
Reply #6 - 01/20/08 at 03:11:58
 
Quote from Tony on 01/20/08 at 02:17:34:

One small concern... The previous exe's for betas were twice the file size of this one.  And I didn't do anything different to reduce the file size.  I'm still in New Zealand, and working off of a system that I'm not quite familiar with, so that may explain the difference, but I'd appreciate any feedback just to make sure.

Good job , I tried the new version.  
Seems to work fine , adding new bodies with the 1SD works ...
But running the program I got this flickering picture ... any idea why ?  Grin
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Re: new beta version
Reply #7 - 01/20/08 at 03:26:06
 
Concerning the 1SD used by JPL I think this is a tricky subject as I think there  is an interference between the standard deviations .  
If there are 6 parameters with each their uncertainty of 1SD and you create a set on SMA of fi 10 bodies , the "outer" values  are less sure . So they must be "weighted" . The central body may have a value 1... the bodies at the side are less likely to occur ...
Second problem is that if one creates 10 bodies ranging in SMA for -1SD to +1SD , each of this bodies has a subset for e , which in turn has a subset in i ,...and so on .  
So it may ( I'm not quite sure )  be necessary to create 10^6 bodies to cover the full range of uncertainty.  
I think both items may be responible for the different results .
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Re: new beta version
Reply #8 - 01/28/08 at 21:40:11
 
Quote from Tony on 01/20/08 at 02:17:34:
One small concern... The previous exe's for betas were twice the file size of this one. And I didn't do anything different to reduce the file size. I'm still in New Zealand, and working off of a system that I'm not quite familiar with, so that may explain the difference, but I'd appreciate any feedback just to make sure.

 
Are you using different compiling software? I think that can change the exe size, if it's compiled more efficiently.
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Re: new beta version
Reply #9 - 01/29/08 at 13:57:19
 
Quote from Mal on 01/28/08 at 21:40:11:
Quote from Tony on 01/20/08 at 02:17:34:
One small concern... The previous exe's for betas were twice the file size of this one.  And I didn't do anything different to reduce the file size.  I'm still in New Zealand, and working off of a system that I'm not quite familiar with, so that may explain the difference, but I'd appreciate any feedback just to make sure.


Are you using different compiling software? I think that can change the exe size, if it's compiled more efficiently.

No, it's the same one only on a different computer.  This time I complied on my laptop instead of my desktop.  It doesn't sound like anyone has any trouble with the new beta, so a smaller file is good.
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Re: new beta version
Reply #10 - 01/30/08 at 14:31:54
 
Tony,  I just tried the latest beta, I have not noticed anything wrong. So it looks good. However I did have one question, are you still planning to implement the ability to edit object using the same variables used to create them. I am working on a system with 12 planets, trying to figure out a stable resonance, and I find it somewhat frustrating having to reenter all the variable because the current edit object just give the XYZ and motion vector.  
 
Thanks
 
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Re: new beta version
Reply #11 - 10/13/08 at 20:14:43
 
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta2008october13.exe
 
This version includes a linear distribution for creating objects.
 
Quote from Mal on 10/13/08 at 09:37:12:
... Can we please have a way to specify the width of the belt that isn't done by percentages? i.e. to specify a distance and then say "+X AU" and "-Y AU". It's much easier to specify the range that way. It'd be even easier to specify the belt's "minimum sma" and "maximum sma", so we could say "100 objects between 0.909 and 1.454 AU" without having to calculate where the middle is first.

 
Ask and you shall receive (unless I ignore you  Wink )
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta2008october13.exe
This version includes a linear distribution for creating objects.
 
What was called "Uniform" was changed to "Random".  There are now 3 modes:
Random
Random Gaussian
Linear
 
To use Linear, enter a range, min,max seperated by a comma.  For example, to create objects between 1 and 5 sma, enter 1,5
I spent 2 hours programming this, and 20 minutes testing it, so there probably will be bugs.
I don't police the input yet, so you can probably crash the program if you forget the comma.
 
Also, you may now choose different distributions for different properties, instead of having to use the same distribution for everything.  Let me know how it works.
 
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Re: new beta version
Reply #12 - 11/04/08 at 20:49:55
 
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta2008November4.exe
 
There is a feature I introduced a few versions ago, but it was buggy, so I fixed and improved it.  It's the "Pointer" feature.  To use it, choose menu View > Show Pointer
It allows you to place an arrow on the screen that points to an object of your choosing.  When you first display the pointer, it points to the Sun.  You can drag it around the screen by dragging the words "To Sun".  To change the object it points to, right click the words "To Sun" and a dropdown list will appear that allows you to change the object.
 
Another change I made is that you can fine-tune the rotation of the rotating frame.  As it was, if you were in rotating frame, Pressing "<" or ">" (you had to hold the shift key) rotated the rotating frame by 36 degrees, so 10 presses made a complete circle.  Now "<" and ">" shift it by 0.5 degrees, and "." and "," (which are < and > without the shift key) rotate the rotating frame by 36 degrees.
 
 
What inspired these fixes is that I wanted to recreate the diagram and trajectory on this page:
http://neo.jpl.nasa.gov/news/2008tc3.html
(I'm hotlinking their image  Wink)
 
And here's my effort

 
 
To try this yourself, download this simulation
http://orbitsimulator.com/gravity/simulations/2008TC3earthcenteredview.gsim
 
This simulation is in a rotating frame with a very long period (quadrillions of years).  This allows you to have basically a non-rotating frame, while giving you the ability to adjust the orientation.
 

  • Run the simulation, and use the "<>,." buttons to rotate the screen until the Sun pointer points straight down.  Don't worry if you're not fast enough to do it before the asteroid impacts Earth.
  • Pause the simulation
  • Re-open the simulation (it should now be the first simulation in the "recently opened" simulations in the File menu.
  • Increase the time step to .06
  • Unpause the simulation
  • Autopilot will pause the simulation for you a few moments before impact, so the screen won't clear on you
  • You should now have the same image as above.

 
With the time step set to .06 seconds, and the graphics update in the Preferences menu set to 15000, you get 1 tick every 15000*.06=900 seconds, or every 15 minutes like the Nasa image.
 
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Re: new beta version
Reply #13 - 12/02/08 at 09:17:10
 
I keep getting random memory errors with this latest build on both my XP box at work and my vista box at home
 
if I have more then about 400 bodies
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Re: new beta version
Reply #14 - 02/25/09 at 15:27:37
 
http://orbitsimulator.com/gravity/beta/GravitySimulatorBeta2009February25.exe
 
menu Time > Time Step Control
 
Enable the control by clicking "on".
Set the minimum distance two objects are allowed to pass before the time step slows.
Set the slow time step.
Set the fast time step.
If you want a log of the time step changes, select the "report" option.
 
For example, if you started with a simulation of all the planets plus Earth's moon, you would want to set your minimum distance to less than about 90% of the moon's distance.  Let's choose 300,000 km.  Since the moon is always farther than this, this prevents it from triggering a slow time step.
 
Enter 2048 for the fast time step.
Enter 1 for the slow time step.
Choose to make a report.
 
Your simulation should run at time step 2048 unless any two objects are within 300,000 of each other, in which case it will run at time step 1 until the close encounter is over.
 
It doesn't check for close encounters with each iteration.  Rather it is controlled by the "Do Events" interval in the preferences menu.  This is set to 50 by default, but you may want to slow it down to 5.
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