egg|nomz|egg changed the topic of #kspacademia to: https://gist.github.com/pdn4kd/164b9b85435d87afbec0c3a7e69d3e6d | Dogs are cats. Spiders are cat interferometers. | Космизм сегодня! | Document well, for tomorrow you may get mauled by a ネコバス. | <UmbralRaptor> egg|nomz|egg: generally if your eyes are dewing over, that's not the weather. | <ferram4> I shall beat my problems to death with an engineer.
<SilverFox> egg, have you tried plotting all the times in all the reference frames?
<SilverFox> all the things*
<SilverFox> fun fact, we use the most superior unit in bloodwork; L/L
<SilverFox> litres per litres
<SilverFox> truly the best unit
<iximeow> what is measured in L per L?
<SilverFox> Hematocrit
<iximeow> oh huh, cool
<SilverFox> the amount of formed elements in whole blood when centrifuged
<SilverFox> so your platelets, RBCs and WBCs
<SilverFox> everything else is nutrient and electrolyte and water basically
<SilverFox> although it'll probably be late-stage, I'll have to add a Complete Blood Count With Differential to the diagnostic tests, these numbers please my autism
<kmath> <botandy> there's love in the air, you didn't follow the decontamination process correctly
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<Profound> How do I write a sequence that has more than one number
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<Profound> Like 2^n*3^m for all real integers n and m
<bofh> \{x_{n,m}\} is the notation I was taught.
<SilverFox> I thought that was an ascii character thing
* UmbralRaptor installs LaTeX on SilverFox's wetware.
<SilverFox> ew condoms
<Profound> O_o;
<Profound> What?
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<Profound> I mean, in like actual math notation
<UmbralRaptor> …
* Ellied can't tell if using balanced XLR cables for high-current stepper motor porpoises is clever or horrifying
<Ellied> I mean it probably keeps the EMI under control pretty well by using twisted pairs for each coil, since the "signals" technically are balanced
<Ellied> (or at least they should be)
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<UmbralRaptor> !acr -add:LITTLE_THINGS Local Irregulars That Trace Luminosity Extremes, The H i Nearby Galaxy Survey
<Qboid> UmbralRaptor: I added the explanation for this acronym.
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<egg|work|egg> UmbralRaptor: O_o
<UmbralRaptor> egg|work|egg: Astronomy ¯\_(ツ)_/¯
<UmbralRaptor> "The perturbation is treated using the methods of perturbation theory, "linearized" by ignoring all terms of order higher than one (quadratic in {\displaystyle h}, cubic in {\displaystyle h} etc...) in the perturbation."
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<bofh> UmbralRaptor: ROFL
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<awang> Hey, finally a news article about that macOS Unicode crash
<awang> !wpn -add:wpn verdigris
<Qboid> awang: Weapon added!
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<awang> Hmmm
<awang> TechCrunch says that the జ్ఞ‌ా crash is only with the default San Francisco font
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<awang> !wpn -add:wpn effective. Power لُلُصّبُلُلصّبُررً ॣ ॣh ॣ ॣ 冗
<Qboid> awang: Weapon added!
<APlayer> Is the period after "effective" intended?
<UmbralRaptor> awang:?
<awang> APlayer: idk, it's there in the examples I found
<awang> UmbralRaptor: It's an earlier version of జ్ఞ‌ా, I think?
<APlayer> Also, whatever that is, it behaves really weirdly when highlighted on Windows
<UmbralRaptor> I guess,
<UmbralRaptor> APlayer: probably because of Arabic being RTL?
<APlayer> Might be
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<APlayer> egg: In a RKF45 implementation, I tried avoiding 6D-vectors by separating position and velocity of the state vectors. I made my f(t, pos, vel) function return the resulting acceleration only, since the returned velocity is the same as the input velocity. I am now implementing the per-step k constant calculations. Every k-constant normally holds a velocity and acceleration component, but since I wanted to avoid
<APlayer> 6D-vectors and my f(t, pos, vel) function returns only the acceleration vector, my k-constants also hold only that. Now, the question is, do I need a separate set of k-constants for the velocities too, or can I refer to the starting velocity?
<APlayer> Sorry for my lacking explanation skills, if I should elaborate something, please tell me
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<APlayer> Also, egg: You already mentioned I'd need to process the difference of the resulting state vectors of different order RK-methods to get a proper error estimate. Is there a rule of thumb for that?
<awang> If I want to make a C# program with a UI
<awang> How much of a mistake is it to use WPF?
<awang> vs Windows Forms?
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* UmbralRaptor is slowly becoming convinced that correctly solving for S given E = A \cdot V \cdot T^n is impossible.
* UmbralRaptor 🔪 thermo.
* APlayer gives UmbralRaptor an Entropy
* UmbralRaptor isentropically detonates.
<awang> !wpn -add:adj isentropic
<Qboid> awang: Adjective already added!
* UmbralRaptor isothermally heats awang.
<UmbralRaptor> >_>
* awang stays at the same temperature
* awang doesn't remember any thermodynamics
* UmbralRaptor passes around homeopathic water.
* awang dies from dihydrogen monoxide poisoning
* UmbralRaptor remembers seeing something about how 2 of the major founders of thermodynamics died from suicide.
<bofh> I know Boltzmann did, not sure who else you're thinking of.
<UmbralRaptor> Ehrenfest
<awang> gesundheit
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<UmbralRaptor> !wpn egg
* Qboid gives egg a harmfully-considered submillimeter sNaN/extension hybrid
<awang> !wpn -add:adj supermillimeter
<Qboid> awang: Adjective added!
* egg stares at #1720
<Qboid> [#1720] title: CKAN Integration | Is it on the roadmap ? It would help a lot, as the install procedure is non-trivial.... | https://github.com/mockingbirdnest/principia/issues/1720
* egg stabs users
* UmbralRaptor stares at awang.
<UmbralRaptor> !w submillimeter
<UmbralRaptor> !g submillimeter
<Qboid> UmbralRaptor: https://www.merriam-webster.com/dictionary/submillimeter [Submillimeter | Definition of Submillimeter by Merriam-Webster] (82000 results found, took 0.58s)
<UmbralRaptor> uh
* awang stares at the floor
<awang> egg: So has the definition of "non-trivial" changed recently or something?
<awang> !g supermillimeter
<Qboid> awang: https://www.ebay.com/b/Sears-Vintage-Movie-Projector/11722/bn_2708060 [Sears Vintage Movie Projector | eBay] (12 results found, took 0.42s)
<awang> Uhhh
<UmbralRaptor> Note phl's comment, it is somewhat harder to install than a normal mod. At least on Windows.
* awang has been spoiled by macOS
<egg> UmbralRaptor: yes, also in a way not handled by CKAN
<egg> awang: apparently nontrivial means trivial or something
<APlayer> Is "suicidal" an adjective yet? Because I want to see suicidal hammers, explosions and formulae
<egg> I mean, considering how we use trivial in mathematics
<awang> What is there besides the C++ runtime that CKAN can't take care of?
<awang> For installation, at least
<egg> educating the user
<egg> :-p
<egg> !choose 🐕|狗|戌
<Qboid> egg: Your options are: 🐕, 狗, 戌. My choice: 🐕
<egg> ;choose 🐕|狗|戌
<kmath> egg: 戌
<egg> awangchoose 🐕|狗|戌
<awang> yes
<egg> raptorchoose 🐕|狗|戌
<egg> bofhchoose 🐕|狗|戌
<APlayer> choosegg
<awang> eggchoose |狗|戌
<awang> Er
<awang> eggchoose 🐕|狗|戌
<UmbralRaptor> awang: జ్ఞ‌ా
<egg> !seen rqou
<awang> Dangit copy/paste
<Qboid> egg: I haven't seen the user rqou yet.
<rqou> egg: more han unification drama? :P
<APlayer> egg: I've run a large set of randomizers to chose the options for you. Based on their conclusive results, you should chose either option with equal probability
<UmbralRaptor> egg: Please stab textbooks/lesson plans/documentation that extensively defines what something is, but provides 0 eggsamples.
<egg> rqou: nah, wondering what to tweet for the new release
<egg> rqou: principia releases every new moon
<rqou> wait really?
<egg> rqou: so there's a release for the new year
<rqou> lol
<egg> rqou: generally I start the release tweet with NEW MOON SYMBOL
<UmbralRaptor> Special dog edition.
<rqou> yup, i feel old
* rqou was born in the year of the dog
<egg> I'm wondering which of 🐕|狗|戌 I should put after that
* UmbralRaptor uh, same.
<awang> egg: How many bug reports do you think you'll get if Principia were CKAN'd
<egg> !u 🐕狗戌
<Qboid> U+1F415 DOG (🐕)
<Qboid> U+72D7 CJK IDEOGRAPH-72D7 (狗)
<Qboid> U+620C CJK IDEOGRAPH-620C (戌)
<UmbralRaptor> But possibly a different dog. o_O
<awang> UmbralRaptor: Ouch, my text renderer
<awang> egg: Why not all three?
<egg> rqou: me rooster
<egg> (also whitequark iirc?)
<awang> Or write your tween in Morse code, with 🐕 as the dots and 狗 as dashes
<awang> s/tween/tweet
<Qboid> awang meant to say: Or write your tweet in Morse code, with 🐕 as the dots and 狗 as dashes
<awang> UmbralRaptor: I'm now sort of curious if a more "normal" IRC client would crash on that Unicode sequence
<awang> i.e. a non-console client
<rqou> you should name it with some of these indic sequences :P https://manishearth.github.io/blog/2018/02/15/picking-apart-the-crashing-ios-string/
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<UmbralRaptor> awang_: not sure.
<APlayer> Uh, egg, sorry to be a bother, but have you received my questions on integrators?
<awang_> Whoops
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* UmbralRaptor 🤖📱
<egg> APlayer: on my phone, haven't looked at them yet
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<APlayer> Alright. When you find the time to answer them, I may re-send them
<awang> జ్ఞ‌ా
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<awang> Yep
<awang> It crashes Terminal.app if it's sent on irc
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<awang> Excellent
<egg> APlayer: well of course you need to do the same to the position as you do to the velocity if you split it, just because you split it for your convenience doesn't mean you should change the formula :-)
<APlayer> <insert a good old rant about Unicode-inconsiderate programmers here>
<rqou> i know how to fix unicode crashes! just forcefully interpret the bytes as windows-1252 :P
<egg> !u 🤖
<Qboid> U+1F916 ROBOT FACE (🤖)
<awang> Can't have Unicode crashes if you don't interpret as Unicode
<egg> rqou: aaaaaaaa
<rqou> mislabel it as iso 8859-1 of course :P :P
<APlayer> egg: I mean that the input velocity of the f(t, Y) formula stays the same as the output velocity. So, unless I am missing something, I can just refer to the velocity from Y_n-1 rather than k_n-1?
<egg> wait the ks and the ys aren't indexed by the same thing, the ks are stages and the ys are steps
<APlayer> What I might be missing indeed but am not sure of is, do the k constants all hold "variations" of the velocity and acceleration, or does that only apply to k_1, k_2 would hold a and a', k_3 would hold a' and a'' and so on?
<APlayer> Well, alright, Y_n-1 and k_m-1
<APlayer> Point being, previous Y and previous k
<egg> uh
<egg> using ' in a context where there are derivatives seems ill-advised
<egg> but I see what you mean
<egg> and no, you have an arbitrary linear combination
<egg> just look at the formula in https://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods#Explicit_Runge%E2%80%93Kutta_methods
<APlayer> ' was denoting derivatives
<egg> okay then you're completely confused
<egg> the k_i all have the same dimension, so they're not more derived for higher i
<APlayer> What I mean is, k_1 holds q' and q''. Does k_2 hold q_2' and q_2'' or q'' and q'''?
<APlayer> Alright, got it
<egg> look at the formulae and expand with y = (x, v) and f(x, v) = (v, F(x)) and you'll answer your own question
<egg> APlayer: and k_2 is the result of f, so it can't have a q''', f returns an acceleration, not a derivative thereof
<egg> that's not the right dimension
<APlayer> Okay
<APlayer> So for k_2, I can substitute the velocity component of k_1 with that of Y?
<APlayer> Well, for k_2 that's clear, yes
<APlayer> But for k_3, I'd use Y_velocity * h * a_21 instead of k_2_velocity
<APlayer> And so on
<egg> what do you mean by and so on
<egg> also Y_velocity * h * a_21 isn't a velocity (since h is a time and a_21 is dimensionless, it's a displacement)
<egg> so something is screwy here
<APlayer> k_4 would use Y_velocity * h * a_21 + Y_velocity * h * a_32 * h * a_21?
<egg> uh
<APlayer> I'd just substitute the terms. I may have failed at that, but...
<egg> okay let me try
<egg> making f autonomous so ignoring the t argument
<egg> and with y_n = (x, v)
<APlayer> I'm sorry for that, I need to go for dinner. I'll be back ASAP, meanwhile, please ;tell me what you wanted to say
<APlayer> Is that OK?
<egg> k_1 = f(x, v) = (v, F(x))
<egg> k_2 = f(x + h a_21 v, v + h a_21 F(x)) = (v + h a_21 F(x), F(x + h a_21 v))
<egg> APlayer: so already here the velocity part of k_2 is not what you said (it involves the previously-evaluated F)
<egg> and it only gets worse from there, with every stage depending on the previous ones
<egg> rqou: so, 🐕, 狗, or 戌 :-p
<rqou> lol all three?
<egg> that's a lot of dogs :-p
<egg> rqou: at least it's not the year of the catrabbit
<rqou> how about "wow, such release"
<rqou> old meme is old?
<egg> rqou: for the catrabbit I'd have to choose between 卯🐈猫🐇兔 :-p
<egg> (which probably means that 戌 is the one to choose, at it's not specific to the animal)
<APlayer> I'm back
<APlayer> egg: I'm still slightly confused by the f(x, v) = (v, F(x)) substitution. x denotes what?
<whitequark> egg: hm?
<whitequark> rooster?
<APlayer> egg: Judging by f(x, v), x should be the position. But in that case I am confused by the F(x) part - that's the integral of the position, or what?
<APlayer> I mean, it should be the acceleration, shouldn't it?
<egg> that's the acceleration as a function of position
<APlayer> But why F(x)?
<egg> I called it F because I am bad at names
<egg> I should have called it γ
<APlayer> And why is it a function when v is not, then?
<APlayer> Ah, because v remains unaltered
<egg> because I don't know what physical problem you're dealing with, but the velocity is just the velocity so I know that the velocity part of f(x, v) is just v
<egg> (I know that you have a 2nd order ODE, in other words)
<APlayer> Alright
<APlayer> So from the evaluation you did, I cannot short-cut the velocity part of the k-constants
<APlayer> That does suck, but well
<APlayer> As for the velocity multiplication with h, that's from the Y_n + h(a_21 * k_1) part
<APlayer> Okay, I am done with the k-constant trickery
<APlayer> egg: Okay, so I've implemented the integrator up to (and including) the Y_n+1 = Y_n + h * (stuff) and Y*_n+1 = Y*_n + h * (stuff) part. The difference between Y and Y* should be used for the error estimate. But how do I produce anything meaningful out of it?
<egg> (featuring a nice goto)
* APlayer last used gotos years ago
<UmbralRaptor> rqou: wow. such gravity. many bodies. wow.
<APlayer> egg: Alright, thank you very much!
<APlayer> What is a truncation error?
<awang> !wpn -add:wpn goto
<Qboid> awang: Weapon already added!
<APlayer> So it's just a fancy term for error?
<APlayer> !wpn awang
* Qboid gives awang a cell
<awang> !wpn -add:wpn cell phone
<Qboid> awang: Weapon added!
<awang> !wpn APlayer
* Qboid gives APlayer a busy walnut
<awang> !wpn egg
* Qboid gives egg a thesis
<APlayer> A busy walnut sounds fun
<APlayer> And I'd guess egg has enough theses already
<awang> !wpn -add:adj lazy
<Qboid> awang: Adjective added!
<awang> !wpn -add:adj eager
<Qboid> awang: Adjective added!
<APlayer> egg: "and by Taylor's theorem, it can be shown that (provided f is sufficiently smooth) the local truncation error is proportional to the square of the step size" Huh?
<APlayer> Why is that so?
<APlayer> https://wikimedia.org/api/rest_v1/media/math/render/svg/23cb25a251c68652d5cbb267a50a1024d73a8a5f Also, Judging by this, the actual error estimate is indeed just the difference between the two solutions? I am certain I am misunderstanding things here, but the definition?
<APlayer> Woops, I missed the time
<APlayer> I should go to bed now
<APlayer> Thank you for spending the time to explain things to someone as thick as I can sometimes be, haha
<APlayer> Anyway, see you tomorrow!
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<kmath> <eggleroy> 🌑戌🐕 Cohen, the new release of Principia, is out, using Estrin's method (for the monomial basis) instead of Clenshaw… https://t.co/EYL7IWV91x
<egg> bofh: twitter thinks this tweet is in romanian
<bofh> 恭喜发财!
<egg> bofh: amusingly, Paul Cohen was born on the year of the dog
<awang> !u 🌑戌🐕
<Qboid> U+1F311 NEW MOON SYMBOL (🌑)
<Qboid> U+620C CJK IDEOGRAPH-620C (戌)
<Qboid> U+1F415 DOG (🐕)
<awang> !u 恭喜发财
<Qboid> U+606D CJK IDEOGRAPH-606D (恭)
<Qboid> U+559C CJK IDEOGRAPH-559C (喜)
<Qboid> U+53D1 CJK IDEOGRAPH-53D1 (发)
<Qboid> U+8D22 CJK IDEOGRAPH-8D22 (财)
<SnoopJeDi> are those chars part of the release title?
<egg> Nah, the release is just called Cohen
<bofh> SnoopJeDi: 戌 is the 11th heavenly branch, signifying that the dog is in the context of being a mnemonic in the 12-year zodiac.
<SnoopJeDi> ah, thanks, I figured from context that char might refer to the zodiac somehow. Appreciate the clarity 😊
<SnoopJeDi> ...I fell *hard* for that Lamé shitpost
<soundnfury> SnoopJeDi: ?
<bofh> SnoopJeDi: I was unable to find a reference for it, sadly.
<SnoopJeDi> soundnfury, little known fact, Lamé here was picked up for drunken disorderly in 1831 in Paris, but ended up doing 6 months in jail in Toulon after shanking his cellmate with a protractor over a disagreement related to the handling of modulus over negative integers
<kmath> <cemerick> little known fact, Lamé here was picked up for drunken disorderly in 1831 in Paris, but ended up doing 6 months in… https://t.co/TqdUTTDDoE
<SnoopJeDi> oops, bad copy was bad