egg changed the topic of #principia to: Logs: https://esper.irclog.whitequark.org/principia | <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/ | <egg> calculating the influence of lamont on Pluto is a bit silly…
<queqiao->
⟨egg⟩ No, Principia computes things from 1951, but internally, before even knowing about the vessels. Then the vessels, which are still being positioned by KSP relative to the planets, are added wherever they are found. So if they have been positioned in a low orbit, they will be found in a low orbit, and will be in a low orbit. A transfer to the moon on the other hand will be going to the void, because the moon is wrong if you do not have...
<queqiao->
... Principia.
<queqiao->
⟨egg⟩ No, Principia computes things from 1951, but internally, before even knowing about the vessels. Then the vessels, which are still being positioned by KSP relative to the planets, are added wherever they are found. So if they have been positioned in a low orbit, they will be found in a low orbit, and will be in a low orbit. A transfer to the moon on the other hand will be going to the void, because the motion of the moon is wrong if you...
<queqiao->
... do not have Principia.
<queqiao->
⟨qazerowl⟩ So if I'm adding principia to a game that's in 2951, it'll sit there and simulate 1000 years of celestial body motion on the first load?
<queqiao->
⟨drveyl⟩ Unless you also tell it a different set of starting positions and times (ie, specify a different start state), yes?
<queqiao->
⟨test_account9540⟩ Going through a singularity and back 😨
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<raptop>
I'd be somewhat concerned about running out of RAM while doing 1000 years of calculations
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<queqiao->
⟨sichelgaita⟩ 1000 years would be 30 minutes of actual computation time. Not great, not insane.
<queqiao->
⟨sichelgaita⟩ Of course, an ephemeris that far in the future will be largely meaningless for the small bodies. JPL Horizons, for instance, doesn't go beyond AD 2500.
<queqiao->
⟨test_account9540⟩ What if principia used an already calculated ephemeris for celestials in RSS 🤔 could it maybe improve performance?
<paculino>
Isn't reading files why loading is so slow?
<queqiao->
⟨siimav⟩ Not 30-minutes-slow.
<paculino>
Is 9540 suggesting only reading files, or files to have alternative start date configs (we have that, don't we?)? I assumed the former.
<queqiao->
⟨egg⟩ The computation of the motion of celestial bodies is the thing that least constrains performance—which is why timewarp is much smoother in the absence of any vessels—, can we please stop wasting precious keystrokes on the discussion of the silly case of the lag on initial game setup where you are somehow playing RSS starting in the year 3000?
<queqiao->
⟨egg⟩ In fact we had to go out of our way to _not_ store the ephemeris for the _past_, and instead to recompute it; because _storing_ it was what hampered performance.
<queqiao->
⟨egg⟩ Wait no, I am misremembering, we were recomputing it from 1950, and now we are recomputing it backward in chunks on demand; I guess it was always too big to store. https://github.com/mockingbirdnest/Principia/wiki/Change-Log#gr%C3%B6bner
<queqiao->
⟨alforath⟩ Can MJ trigger stating on Principia node? I know how to align to node with Smart AAS