Kerbal Space Program

Here is a video of the effect in Vanilla KSP with the Kerbal X craft using windows 7 64bit 32Gb ram GTX 570 I7

http://www.youtube.com/watch?v=Tt_Zr0es_7k

After more testing this effect is centered on the halfway points between orbital markers. At Ap and Pe the effect is reduced below resolution. On an 80km orbit the largest effect is about 45m change to the height of each marker.

It is possible to deorbit a craft from an 80Km orbit using only this effect. The eccentricity of the orbit seems not to be a factor.

That comes from the craft being on rails at warp and entering physics (leaving warp) makes micro wobbling adjust the orbit on that scale.
I think it's not really a bug but rather a side effect and I don't think it's easy to avoid.

And 45m jumps are a joke, make a 20m/s orbit around Gilly, your AP / PE might circle all around it constantly, the more circular (less eccentrical) the worse it gets.

Thank you for restating my bug report but I cannot see how your post was helpful. I have deorbited a craft with this effect and only posted the bug here after being urged to do so by a Mod who finally realised it was not the issue you are talking about. The effect is not changed by whether the orbit is circular or not, it just becomes more noticable. I have stated a very easy fix to this issue in the thread I started in the bug reporting area on the forum.

I am FULLY aware of the problems of which you speak which is why I have noticed this bug.

You are misunderstanding this bug on the most basic level. This is not a bug caused by circular orbits. This is a bug that will change your orbit whether it is circular or not and by choice you can make it more eccentric or more circular in a reliably predictable and repeatable (read that as fixable) way.
This bug is fixable but the problems with circular orbits are not. This is not caused by the `problems of going from rails to physics` as you and a lot of people seem to think, it is a bug in the implementation of that. If you cannot see that one is hard maths with all its problems and one is a bug then please do not post here.

"the craft being on rails at warp and entering physics (leaving warp) makes micro wobbling adjust the orbit on that scale." this would not cause this effect which is consistant in applying force in the same direction and at a force which can be calculated as a sin (possibly) of the percentage of the distance between Pe and Ap with one side of the orbit giving a circularising effect and the other half increasing eccentricity.

A calculation error caused by insufficient resolution would not produce such a consistent predictable effect. This is not the issue you are talking about.

This is a bug in the calculations at the point of going on rail to off. It can be fixed by looking at that code and seeing the mistake. The issue you describe cannot and I would not report that as a bug.

To pre-empt anybody else who wishes to waste my time as has been done far too much in the other thread. You may think this is not a bug but it has been established by more than one mod that this is a bug, it is serious enough to be reported here and that I should do that which I have.

PLEASE DO NOT REFER TO THE PROBLEMS OF AN ORBIT WHICH IS TOO CIRCULAR HERE OR CALCULATION RESOLUTION LIMITS AS THIS IS NOT THOSE ISSUES YOU ARE CONFUSED AND YOU WILL CONFUSE OTHERS PLEASE DO NOT THREADJACK

Could people please read the sentence above before posting. Sorry for shouting, I have tried many times without in the other thread and people just want to argue...

This is clearly a (very) consistant rounding error when going between the rails on warp and the real-time physics.

Yes, it is a rounding error, however consistant it may be.

To pre-empt anybody else who wishes to waste my time as has been done far too much in the other thread. You may think this is not a bug but it has been established by more than one mod that this is a bug, it is serious enough to be reported here and I was advised that I should do that which I have.

Could people please read the sentence above before posting.

Thank you for your reply and for confirming the bug. It is very possible I did not react well as I only posted here to get away from the bug forum where I had been badgered by a particular user about this until I was told that I had found a novel bug (which had not been posted on the bugtracker) by a Mod who understood what I was trying to say. I decided this problem should have a post on the bugtracker so it could be dealt with by the correct people. This is what I have done. All I wanted was to post the information describing the bug so that the people who actually deal with these issues (yourself I assume) could look at the information and make a decision as to exactly what was going on and decide whether it was worth addressing. This I have done. I did not and still do not wish to be engaged in a big debate about this. I just wanted to report the bug, how it manifests and an idea for a possible solution in this particular case and then get on with my life.

As a slight aside, I know abut the calculation problems you refer to, why Ap and Pe `wobble` when your orbit is fairly circular, and the moving universe as opposed to the moving craft and the calculation problems connected with this (or at least to the level described in the article about that) and the precision issues connected with going on and off rails. Using KOS (for automation) and this effect, I have deorbited a craft which was at a circular 80km orbit around Kerbin. This is how I noticed the effect, my KOS program could not reach Pe (IIRC) as leaving warp moved it so much my program tried to warp to it again. I now use this effect to get circular orbits (within 1m) using KOS and warp. I now just run a program I made called bugcirc. (which just warps to makes sure it is on the right half of the orbit and goes in and out of warp until the orbit is circular) and I get a perfectly circular orbit using no fuel. To my mind a rounding error would not be quite so predictable.

Whatever the cause, a very simple solution would be to simply adjust the values by the amount they are in error. If it is a rounding error (and by implication unfixable) then it is one that introduces such a predictable change in the values that it could be calculated based on your orbital information and eliminated in the case I have described by adjusting the underlying calculations. If it can be predicted, it can be mitigated. There is no need to increase precision.

Truepikachu, I did misunderstand bloodyrain2K`s post (sorry bloodyrain2K) but I disagree with the conclusion still. The bug I reported was not an inevitable result of the process but an error in the calculation code for that process. One is not fixable the other very much is.

I have done some research on rounding errors and looked at the cases of the circularising bug as a result of so many people contradicting things I thought to be fact. I can now be more definite about my statements.

"the bug which this entry was created for is caused by errors with respect to floating point numbers" is not accurate. Errors in floating point resolution would produce a random effect, not a predictable one. Looking at the way the bug manifests eliminates this as a possible cause.

I can now say for sure this bug is neither of those. Rounding errors do not produce predictable effects due to their nature and the effect happened with all orbits, not just circular ones. These two facts eliminate those two possible causes.

On a nice note, it seems this bug has been eliminated in 0.23.5, looks like it was very possible to fix and may have been so easy that it was fixed in the course of going over the code for ARM...

I apologise for my harsh reaction to the effect I noticed being called a joke and for people telling over and over the error in calculation code was a rounding error (which produces different effects) I can understand now this is part of the process but I still cannot see how it helps. In this case they were a distraction from the actual bug.

IMO this bug has now been fixed. I have tested the same conditions with 0.23.5 and the effect is gone or is below altimeter resolution

To me the very fact the bug has been eliminated says that it was not an inevitable result of the way physics is handled in KSP or a rounding error and it was, in fact, a bug of the type I described.

In the last 32 years that I have spent finding bugs, I have found that `known bugs` often hide other bugs which have similar but distinct effects and can only be distinguished by knowing what sort of code manifests which sort of behaviour and being able to eliminate causes based on this. Relating bugs based purely on their effects (like the circular bug/rounding error and this one) can lead to bugs not being fixed.

This appears to be a case in point.

Giving this a bump for visibility due to it possibly causing the unexplained loss of craft.