UmbralRaptor 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> … one of the other grad students just compared me to nomal O_o | <ferram4> I shall beat my problems to death with an engineer.
<bofh> egg|zzz|egg: true.
<UmbralRaptor> egg|zzz|egg: Tuco the telescope operator?
<bofh> egg|zzz|egg: helps I also learned Functional Analysis properly immediately after. And then convex geometry/optimization.
* egg|zzz|egg still not clear whether UmbralRaptor has opposable thumbs
<egg|zzz|egg> bofh: that I haven't learned :-p
<egg|zzz|egg> (see also principia just having a Bisect for root finding :-p)
<egg|zzz|egg> bofh: though tbh a lot of principia's fancier stuff falls directly under https://twitter.com/sigfig/status/922151296429428736
<kmath> <sigfig> was there ever a time when it was actually easier to learn a field of math from introductory texts rather than from current research
<egg|zzz|egg> (amusingly sigfig starred the principia repo :-p)
<bofh> yeah see I basically use the most optimal root finder that I can apply.
<bofh> which usually means L-BFGS with DIIS extrapolation.
<egg|zzz|egg> bofh: going through the list of people who starred the principia repository brings up strange things: a pole who writes Ada https://github.com/darkestkhan
<UmbralRaptor> Are they doing condensed matter physics?
<kmath> https://twitter.com/usa_satcom/status/921874019648860161 <usa_satcom> Today's GOES-16 Full Disk. This satellite is going to move out of range for me soon. GOES-17 in 2018. https://t.co/sPUQcYtRby
<bofh> UmbralRaptor: doesn't look like it?
<egg|zzz|egg> bofh: I remember watching that one the year I learned elementary topology https://twitter.com/stephentyrone/status/922255681574658048 :-p
<kmath> <stephentyrone> This is a strong contender for “best Downfall meme”: https://t.co/1e2NSGXQ3y
<kmath> <barrelshifter> Boy adventure https://t.co/30OM7lBua4
<UmbralRaptor> uncomfortable cat?
<bofh> Huh, apparently a heaping tablespoon is a bit too much extra salt for instant noodles, even for me.
<bofh> Had to dilute it a bit with water >_>
<Iskierka> "heaped <>spoon" is the worst kind of measurement
<Iskierka> different materials heap differently. Even different brands
<bofh> ~4.5g granulated iodized table salt, according to a scale (4533mg in this test)
<bofh> better? :P
<Fiora> 4.5g? that's a pretty reasonable amount of salt
<Fiora> i may be biased
<Fiora> as someone who eats soy sauce plain
<bofh> Fiora: I've gone that, it's tasty.
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<egg|zzz|egg> bofh: what percentage in mass does that represent
<egg|zzz|egg> (I am terrible at sleeping >_<)
<egg|zzz|egg> !wpn Iskierka
* Qboid gives Iskierka a 22 AWG snakehead
<bofh> egg|zzz|egg: percentage in mass?
<egg|zzz|egg> of the food
<egg|zzz|egg> (because I have a hard time figuring out how salty those 4.5 g are if I don't know what's around them :-p)
<bofh> add another 650mg (actually prolly more than that, since that's just Sodium) from the flavour packet and so the whole ~5.1g is dissolved in ~450mL of water.
<kmath> <jasonlatour> PORKY PIG VS. RYAN NORTH. A true enough story. Featuring @ryanqnorth & @zdarsky. As told by me... https://t.co/8H4IxvjYM3
<UmbralRaptor> !wa atomic mass sodium
<Qboid> UmbralRaptor: sodium | atomic mass: 22.98976928 u (unified atomic mass units)
<UmbralRaptor> !wa atomic mass chlorine
<Qboid> UmbralRaptor: chlorine | atomic mass: 35.45 u (unified atomic mass units)
<UmbralRaptor> !wa 5.1/0.45*2/(22.98976928+35.45)
<Qboid> UmbralRaptor: 5.1/0.45×2/(22.98976928 + 35.45): 0.387863726122271690574796647565865726612031324341783347072...
<egg|mobile|egg> That doesn't seem unreasonable? ... Suddenly I realize I'm comparing with figures for sauces or water wherein I boil potatoes
<UmbralRaptor> So 0.39 molar?
<bofh> It's not, honestly.
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<bofh> ...I swear to fucking god this terrible bro-country song I heard on the radio at the local 24-hour convenience store AUTOTUNED THE GUITAR TRACK.
<egg|zzz|egg> !wpn bofh, Fiora, Iskierka, et al.
* Qboid gives bofh, Fiora, Iskierka, et al. a RS-232 Taylor bustard which vaguely resembles an explosion
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<egg|afk|egg> !wpn whitequark
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<egg|work|egg> !wpn whitequark
* Qboid gives whitequark a nitrated dynamo
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<egg|work|egg> !wpn InfectedRaptor
* Qboid gives InfectedRaptor a Jovian zeta motor/chlorofluorocarbon hybrid
<APlayer> InfectedRaptor: Uh, get well soon?
<InfectedRaptor> APlayer: I'll try.
<InfectedRaptor> !wpn egg
* Qboid gives egg a fluorine spectrometer-like involution
<APlayer> Qboid has a fluorine surplus, currently?
<InfectedRaptor> current status: https://photos.app.goo.gl/a4NfviAmHMieG4b12
<InfectedRaptor> Fluorine is a somewhat rare element, so I'm not sure what Qboid is doing.
<APlayer> Oooh, what book is that?
<APlayer> s/book is/books are/
<Qboid> APlayer meant to say: Oooh, what books are that?
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<InfectedRaptor> They're classical mechanics texts.
<APlayer> Uh, the images are the same :P
* InfectedRaptor ? ?
<APlayer> Ah, that's noice
<InfectedRaptor> Yeah, they've both got the amusing warnings about not selling the books outside of the Indian subcontinent.
<egg|work|egg> O_o
<egg|work|egg> !wpn whitequark
* Qboid gives whitequark an ordinal
<egg|work|egg> !wpn InfectedRaptor
* Qboid gives InfectedRaptor a sodium term-like formalism
<egg|work|egg> !wpn bofh
* Qboid gives bofh a chocolate ordinal
<egg|work|egg> oh, more on that stuff from yesterday https://twitter.com/stephentyrone/status/922461886934810625
<kmath> <stephentyrone> @FioraAeterna Optimal multiply chains are NP complete in the stupidest way possible—the obvious trivial algorithm i… https://t.co/DFUgN9DLXL
<egg|work|egg> !wpn Fiora
* Qboid gives Fiora a triaxial profuct
<InfectedRaptor> egg|work|egg: because the "India" editions cost $20, while US ones cost $200.
<kmath> <chemDrV> ACS student chapter is selling a periodic table of cupcakes! https://t.co/2KBAZuf0gl
<APlayer> egg: Not sure I understand that tweet...
<InfectedRaptor> ^bofh
<APlayer> Let's begin with optimal chains
<APlayer> Oh gods, even more complicated maths
<APlayer> I mean, I usually like that, but come on. That's a bit /too/ complicated
<egg|work|egg> !seen TechnicallyAsleep
<Qboid> egg|work|egg: I haven't seen the user TechnicallyAsleep yet.
<egg|work|egg> !seen TechnicalFool
<Qboid> egg|work|egg: I haven't seen the user TechnicalFool yet.
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<kmath> https://twitter.com/RichFelker/status/922499003270533120 <RichFelker> @FioraAeterna No it's O(1) because multiplication isn't associative and there's no reordering that's equivalent. ;-)
<egg|work|egg> Fiora: alternatively, do the thing with some additional precision so you're last-bit-precise on the product, and then reorder *that* to keep it correct
<egg|work|egg> :-p
<Fiora> egg|work|egg: still wrong
<egg|work|egg> Fiora: ?
<Fiora> the best thing about """precise""" floating point
<Fiora> is that the precise order of roundoffs matters
<egg|work|egg> yeah, I know
<Fiora> so you can be wrong by being more correct
<egg|work|egg> I badly worded that
<egg|work|egg> I meant "consider the problem of reordering while keeping the correctness of the whole, on e.g. code that does last-bit-precise multiplication of 5 binary64 floating point numbers"
<egg|work|egg> (mind you there might be no such reorderings, I'm even sure what the code would look like to start with)
<egg|work|egg> Fiora: I *think* you need an FMA to do exact double-double multiplication, you might need one there too?
<TechnicallyAsleep> Hullo eggping
<egg|work|egg> o/
<egg|work|egg> TechnicallyAsleep: there's someone on the principia thread who seems rather excited about their feature request :-p
<TechnicallyAsleep> "rather excited" eh?
<kmath> <FioraAeterna> @RichFelker @pikhq i'm part of the cabal that tells people to never use == on floats
<egg|work|egg> (though I guess given what you've told me of graphics things that might be sound advice for graphics)
<Fiora> It's probably okay for things like zero and so on
<Fiora> I mean, graphics is that wonderful place where people just use clamp() every 4 ops
<Fiora> lol
<egg|work|egg> :D
<egg|work|egg> Fiora: so from the "I can actually assume IEEE 754 and non-flushed denormals" side of things == often means "I'm removing a removable singularity" or something like that (need to look at the conditioning around it often, but not in principle bad)
<TechnicallyAsleep> well Scotskerb has an interesting quirky behaviour with a mod.
<egg|work|egg> TechnicallyAsleep: yeah just saw that
<egg|work|egg> Fiora: also testing of course, where I have things that I know should be exact; but that's rather a special case
<egg|work|egg> bofh: hm, what are uses of equality that are not tied to removing a removable singularity
<TechnicallyAsleep> insert identity politics based joke here.
<kmath> <FioraAeterna> @RichFelker @pikhq fun fact: there's a GPU where in some cases (max(a,b) == a || max(a,b) == b) returns false for non-NaN inputs
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<kmath> https://twitter.com/stephentyrone/status/922501944563859458 <stephentyrone> @RichFelker @FioraAeterna @pikhq Keep in min @FioraAeterna lives in GPU land where no one cares about the low ~20 b… https://t.co/QltRzviGmv
<kmath> https://twitter.com/stephentyrone/status/922505697908215808 <stephentyrone> @science_dot @FioraAeterna @RichFelker @pikhq Aaaaaah, no, my eyes! There are times when it's perfectly appropriate to use exact equality!
<kmath> https://twitter.com/stephentyrone/status/922509465274011648 <stephentyrone> @FioraAeterna @science_dot @RichFelker @pikhq Special shout-out to C# and it's completely insane definition of epsi… https://t.co/3QfQAHl7R5
<Iskierka> playing matchmaker between a turtle and a rat. This is a weird game
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<egg> !wpn Fiora, bofh, et al.
* Qboid gives Fiora, bofh, et al. a valid croissant
<egg> TechnicallyAsleep: "rather excited" mostly in that they requested the same thing a hanful of posts above :-p
<egg> !wpn whitequark
* Qboid gives whitequark a Schmidt-Cassegrain solderless falcon
<egg> !wpn InfectedRaptor
* Qboid gives InfectedRaptor a boron polytrope
<InfectedRaptor> egg: currently struggling with "simple" orbital mechanics problems.
<egg> InfectedRaptor: do tell
<InfectedRaptor> well, sort of. One has a Yukawa potential.
<TechnicallyAsleep> arhar
<InfectedRaptor> 19b and 20b https://photos.app.goo.gl/f3oJPrIR7BXamz0j1
<kmath> <FioraAeterna> @RichFelker @pikhq @hikari_no_yume omfg I didn’t know it was -supposed- to be able to do it and they botched it
<InfectedRaptor> Okay, I have a bad solution for 20.
<InfectedRaptor> (make assumptions so that you can claim simple harmonic motion)
<kmath> https://twitter.com/atonal440/status/922527564912103424 <atonal440> @bofh453 What I want to know is if morgoth's density exceeds the Chandrasekhar limit, but I don't think it does.
<egg> !wpn bofh
* Qboid gives bofh a physicist
<bofh> redundancy :D
<bofh> (hey just what I need to compute a Chandrasekhar limit!).
<egg> bofh: [from above] can you think of any usages of floating-point equality that are not 1. last-bit work 2. removable singularities?
<bofh> Not off the top of my head, but let me actually think about it more.
<kmath> <barrelshifter> he’s tired of my bullshit https://t.co/AHeg8kdvG4
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<egg> !wpn Sarbian
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<Fiora> egg|work|egg: i see you are enjoying that thread
<egg> Fiora: :D
<egg> Fiora: also I'm not sure how to navigate twitter's conversation trees
<egg> Fiora: do you understand what is going on with the C++ modules proposals?
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<Fiora> i have no idea what a C++ module is
<egg> basically same, there's this thing https://clang.llvm.org/docs/Modules.html and there's this stuff and I can't tell whether they're related http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0142r0.pdf
<egg> hm, I seem to recall whitequark saying something about modules a while back, maybe she has a better understanding of those things
<Qboid> 7d 0h 0m 0s left to event #12: 무궁화 5A호/Falcon 9 v1.2 [at 2017-10-30 19:34:00]. Say '!kountdown 12' for details
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* InfectedRaptor sobs
<egg> InfectedRaptor: ?
<InfectedRaptor> Frustration at the problems seeming insoluble.
<egg> InfectedRaptor: what do you get for 19a?
<InfectedRaptor> Nothing easily accessible, as that was last week.
<InfectedRaptor> r" + ((k/m)r^-2 + (k/ma)r^-1)exp(-r/a) = 0
<InfectedRaptor> mr²θ' = l
<InfectedRaptor> er, the r" equation is wrong.
* egg thinks he's going to get nerd-sniped into actually doing this one
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<InfectedRaptor> oops
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<kmath> https://twitter.com/bofh453/status/922579058520715271 <bofh453> Kindly go fuck yourselves with cacti, Elsevier. (Thank heavens for @Sci_Hub). https://t.co/j9Z9jSqiRu
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<InfectedRaptor> bofh: Incidentally, Lidov's paper (on the Kozai-Lidov mechanism) from around then is also paywalled.
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<egg> InfectedRaptor: blarrgh, no idea; ask bofh, who actually has taken a classical mechanics (/me is actually rather clueless there)
<InfectedRaptor> blarg
* egg has tried some series eggspansions but they're not very effeggtive
<InfectedRaptor> Hilariously, exp(x) ≈ 1+x does significantly simplify the problem. Not enough to make it integrable, but still…
<bofh> Wait, really? I think that should suffice.
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<bofh> At the very least that turns into a usable DE.
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<InfectedRaptor> It ends up being r" + Ar^-2 + B = 0, right?
* egg confused
<bofh> Erm, r^-1 unless you misplaced a bracket.
<bofh> on the A term.
<egg> for 2b, I'd think one could poke at the force for perturbed r around ρ and expand that to get an ODE for the radial perturbation in the nearly-circular case?
<egg> but then I get the wrong signs to start with
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<egg> argh right in the rotating frame, a radial perturbation isn't going to work >_<
<egg> bofh: but shouldn't some manner of perturbative thing in the rotating frame work? though if it's not a radial perturbation maybe it's not worth it
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<egg> !wpn bofh
* Qboid gives bofh a Radon capacitive star
<egg> !wpn whitequark
* Qboid gives whitequark an adiabatic gantlet
<egg> !wpn Fiora
* Qboid gives Fiora a pressurized honed eidolon
<egg> !wpn InfectedRaptor
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<whitequark> !wpn egg
* Qboid gives egg an unremarkable resonance
<InfectedRaptor> !wpn egg|zzz|egg
* Qboid gives egg|zzz|egg an antimony interferometer which strongly resembles a perturbation
<whitequark> котя is better
<InfectedRaptor> … a perturbation? AAAAAAA
<whitequark> especially when left alone without the kitten running around
<egg|zzz|egg> whitequark: yay!
<egg|zzz|egg> whitequark: where is the kitten?
<egg|zzz|egg> whitequark: also, do you have any котяpics?
<egg|zzz|egg> whitequark: also do you know what's going on with the modules proposal and the weird clang modules? they seem nearly unrelated somehow Ꙩ_ꙩ
<egg|zzz|egg> !acr -add:ALPHA Antihydrogen Laser PHysics Apparatus
<Qboid> egg|zzz|egg: I added the explanation for this acronym.
* egg|zzz|egg pokes Coriolis with a stick
<egg|zzz|egg> bofh: InfectedRaptor: ok I'm not convinced that trying to look at differential equation for the perturbation from the circular orbit in the rotating frame leads to sanity
<InfectedRaptor> Hah
<InfectedRaptor> … wait, I should have eaten today.
<egg|zzz|egg> ask whitequark to teach you how to catch a moth?
<bofh> https://mobile.twitter.com/bofh453/status/922612481679175680?p=p at least I THINK this is GL(4) and not O(4)
<kmath> https://twitter.com/bofh453/status/922612481679175680 <bofh453> Notation hell continues with the Lie Group ?₃, which, for fuck's sake, is "GL(4,ℂ)" really that much harder to write?
<bofh> but who the hell created this notation?
<egg|zzz|egg> I had never seen that
<egg|zzz|egg> I was happy never to have seen it
<egg|zzz|egg> why 3
<InfectedRaptor> egg|zzz|egg: moths seem a bit low on calories.
<egg|zzz|egg> InfectedRaptor: eat *several* moths
<InfectedRaptor> Especially since I'm probably 10-15x the mass of kotya.
<egg|zzz|egg> whitequark: what is the mass of котя
<egg|zzz|egg> !wa mass of a velociraptor
<Qboid> egg|zzz|egg: Velociraptor (dinosaur) | weight: (16 to 18) kg (kilograms)
<bofh> egg|zzz|egg: also apparently did you know that ?(0,0) is isomorphic to the direct sum of ?₃ and (ℰ)?
<egg|zzz|egg> (0,0)
<egg|zzz|egg> ^ see, this notation has a self-referential thing to it
<bofh> this notation is FUCKING HORRIBLE