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.
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<UmbralRaptop> Are catpix worth it if the camera app somehow needs so much ram that your irc client gets killed?
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<iximeow> UmbralRaptop: yes
<UmbralRaptop> Note to self: do not tell Office 365 to install updates on a system that currently does not have internet access.
<Ellied> eep
<Ellied> SnoopJeDi: okay WOW that's cool
<rqou> egg, bofh: are you familiar with relative degree and feedback linearization?
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<UmbralRaptop> Dessert Lunch Site? https://photos.app.goo.gl/jAHNh52Hr4hRQtzh8
<UmbralRaptop> (partial credit for this joke goes to taniwa)
<Ellied> what's with the little coat hangers next to the kerbals' names
<ferram4> egg|zzz|egg, I am sorry, abou the delay, but I have no idea. Not something I've been paying attention to.
<rqou> anybody here familiar with sliding mode control?
<rqou> hmm, it appears my sliding mode control simulation is not numerically stable, but good enough for homework purposes
<UmbralRaptop> Ellied: click on them to change the kerbals' clothing.
<bofh> whitequark: I was this close to tweeting that "no, can't be done, b/c the string contains repeats of literals in it and those'd get converted to matches in the LZ77 encoder" but no they're all of length <= 2 so you just get some extra bits and a trivial reversible transformation applied to the string.
<bofh> 1 sec and I am pretty sure I'll have a binary sequence that does exactly what you want.
<rqou> bofh plz 2 halp me with numerics? :P
<bofh> rqou: sadly not hugely familiar with sliding mode control, s'ry :/
<rqou> ok, i'll just turn in the "homework-quality" simulation :P
<rqou> hmm now i have a new question about diffeqs
<rqou> i have that xdot = f(x)
<rqou> f(0) = 0
<rqou> W(t) = x(t)^T x(t)
<rqou> |f(x)| <= L|x|
<rqou> i have proven that -2LW(t) <= Wdot(t) <= 2LW(t)
<rqou> i need to show that |x(t)|e^{-Lt} <= |x(t)| <= |x(0)|e^{Lt}
<rqou> but i have no idea how to begin showing that
<rqou> it's not any of the bounded-input things that i learned about
<rqou> because there isn't actually an input here
<egg|zzz|egg> !wpn whitequark
* Qboid gives whitequark a voltage-dependent torpedo
<egg|zzz|egg> !wpn rqou
* Qboid gives rqou a polarized triode
<whitequark> bofh: ahem
<whitequark> did you write that one or should i resume my attempt
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<egg|zzz|egg> !u ߀
<Qboid> U+07C0 NKO DIGIT ZERO (߀)
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<bofh> whitequark: feel free to resume, I'll resume myself this evening
<bofh> (it's marginally more complicated than I said earlier, since the function isn't bitrev(ch + 0x30), it's that if ch is <= 143 & 2*bitrev(ch + 0x30) + 1 for 9 bits of output if ch is > 143. makes inverting it irritatingly harder).
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<egg|anbo|egg> current status: cat
<egg|anbo|egg> !wpn bofh, UmbralRaptop, whitequark, et al.
* Qboid gives bofh, UmbralRaptop, whitequark, et al. a vile page table
<bofh> oh, so a 5-level pagetable? :P
* UmbralRaptop pets egg|anbo|egg.
* egg|anbo|egg is petted
<egg|anbo|egg> XMM?
<Qboid> egg|anbo|egg: [XMM] => X-ray Multi-Mirror
<egg|anbo|egg> YMM?
<egg|anbo|egg> MMX?
<egg|anbo|egg> bofh: is there a difference between pand and andpd?
<bofh> you mean andps (andpd is literally the exact same instruction path except it's a byte longer and generates SIGILL on pre-SSE2 machines)
<bofh> and the answer is... on recent systems, no. on Nehalem-gen yes, in the sense that the "floating-point" bitwise ops like andps, orps, xorps went thru port 5 (the shuffle unit), whereas the integer ones went thru the SIMD integer processing unit, and there was no penalty for domain crossing, so you generally wanted to use the FP ones. pre-Nehalem the situation is even weirder, b/c there would be a 1-cycle
<bofh> penalty in latency for using integer and float ...
<bofh> ... ops on the same xmm register in sequence, but it only on *some* generations applied to bitwise ops. moreover, on say Conroe this exists but the FP versions also are 1 cycle faster, so it cancels??? it's bloody weird.
<bofh> in terms of effects: it's a SIMD bitwise AND. of course there's no difference between the two at all.
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<egg|cat|egg> bofh: sigill on pre-sse2 machines is not a concern for principia :-p
<egg|cat|egg> bofh: also O_o
<egg|cat|egg> bofh: and what changed that makes it the same on recent systems?
<bofh> As of HSW it's no longer the case that there's *exactly* one execution port that can do SIMD shuffles. :P
<bofh> (I've actually written SIMD FFT code that is bottlenecked pre-HSW on *shuffles*).
* egg|cat|egg is confused
* egg|cat|egg pets a cat
<UmbralRaptop> Apparently I get hit with a $5 service fee if pay my water bill online.
<UmbralRaptop> (raised I think?)
<APlayer> UmbralRaptop: Well, running the server costs money. Who will pay for it, if not those who use it? ;-)
<egg|cat|egg> UmbralRaptop: why don't you use a more conventional payment method like sending your messenger with a purse of silver and clay tablets
<UmbralRaptop> APlayer: well, they supply an envelope so mailing a check costs ~$0.50…
<UmbralRaptop> egg|cat|egg: Last time, they messed up the delivery of copper ingots.
<APlayer> Send your servants to deliver the mail in the supplied envelope. :-)
<egg|anbo|egg> bofh: uh wat, trying both with iaca, the andpd/andnpd/orpd version of my cbrt is analysed as slower both on hsw and snb than the pand/pandn/por Ꙩ_ꙩ
<egg|anbo|egg> bofh: wait no it's the reverse
<egg|cat|egg> so that makes more sense i guess
<egg|cat|egg> !wpn Ellied
* Qboid gives Ellied an associative sNaN which vaguely resembles an underflow
<egg|cat|egg> bofh: nevermind, it does say it's slower on snb
* egg|cat|egg utterly confused
<egg|cat|egg> ok, pand &c. version, iaca says 123 cycles on snb, 120 on hsw
<egg|cat|egg> andps/andnpd &c., iaca says 125 cycles on snb, 121 cycles on hsw
<egg|cat|egg> bofh: wat
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* Ellied wonders if any languages have ints become NaN on overflow or underflow
<egg|cat|egg> Ellied: not nan, but setl has omega
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<egg|cat|egg> bofh: wait, it makes sense considering what you said? since I'm not using the integer processing unit at all otherwise
<egg|cat|egg> bofh: except if I run it for throughput analysis it says they're all on port 5 anyway so wtf
<egg|cat|egg> confusion intensifies
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<egg|cat|egg> bofh: and actually measuring, on skylake it's noticeably faster with andps etc.
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<APlayer> After a chess game of four hours yesterday, my cognitive apparatus has not yet recovered enough to be able to think
<APlayer> May also be because I slept for 11 hours
<UmbralRaptop> That shouldn't be a problem.
<UmbralRaptop> Insufficient caffeine / water / food?
<APlayer> Anyway, I am mentally devastated. The food and water part seem okay, but I don't drink coffee
<APlayer> (I know I am an embarrassment for the programming and academia communities)
<UmbralRaptop> Heh.
<APlayer> It's weird. I am not tired as in I want to sleep, but I /am/ tired as in I can't focus and I have this weird feeling in my eyes as if I wanted to sleep
<kmath> <xdroop> @GeologyCat @ObservatoryCats Way ahead of you bro https://t.co/irDQbnGtHL
<APlayer> That's one smart cat
<bofh> APlayer: for that I specifically recommend amphetamines.
<egg|anbo|egg> !wpn bofh
* Qboid gives bofh a Giger ray tube/⚛ hybrid
<APlayer> bofh: I am pretty sure I don't have a stock of that in my basement, LOL
<UmbralRaptop> Giger counters measure fear, right?
<egg|anbo|egg> bofh: lolwut in the version with rescaling against over/underflows pand is faster ??!
<egg|anbo|egg> bofh: why does nothing make sense
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<Ellied> I had a dream that I accidentally blew up the detector tube of one of my uni's nice geiger counters with a bremmstrahlung x-ray source I made as a project for some class
<Ellied> my prof said he'd try to keep me from getting in trouble with the other faculty, but also made me go see a doctor to make sure the radiation dose to my hands wasn't life-threatening
<UmbralRaptop> !!!
<UmbralRaptop> Oh, dream.
<kmath> <comex> @ https://t.co/gt2G5gV6Ms
<iximeow> oh cool twitter actually renders the quote tweet
<iximeow> clicking it produces broken page, trying to rt or quote through the api fails
<egg|anbo|egg> UmbralRaptop: it's cloudy above ANBO
<egg|anbo|egg> bofh: I don't know what to make of those benchmark results Ꙩ_ꙩ
<UmbralRaptop> egg|anbo|egg: have you tried turning the sun off for a few weeks?
<egg|anbo|egg> any suggestions on how to do that
<egg|anbo|egg> bofh: do you want to try benchmarking this nonsense on your side?
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<egg|anbo|egg> bofh: https://hastebin.com/fojoqiyipi.cpp if you feel like poking at it
<Ellied> UmbralRaptop: yes, presumably referencing the time I held a geiger counter over the XRF while it was running and got it to go EEEEEEEEEEEEEEEEEEEE
<Ellied> (which I believe was still a negligible dose for the few seconds or so it was on)