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.
<kmath>
<NuclearAnthro> I OPENED TO A RANDOM PAGE AND I AM ALREADY FILLED WITH PURE RAGE AND DISTRESS. https://t.co/eayvHJGnoY
<UmbralRaptor>
Since I'm unable yo load the pics, is this the page with maritime safety, and bonkers conspiracy theories that nuclear weapons and spaceflight are hoaxes?
<Iskierka>
is a book by a "Akio Nakatani" which appears that it may be a fake name
<Iskierka>
book should be first google result as amazon listing
<UmbralRaptor>
Ah, this is something else.
<Iskierka>
it appears to criticise the 100-ton pre-test and gadget having approximately the same size creater while ignoring that gadget is on a 100ft tower (5x taller, where naive energy scaling vs volume would suggest a 4.6x larger crater for same position), and neglects to consider differing dynamics for an almost-conventional detonation
<Iskierka>
interestingly article does not clearly source where it obtains the 100-ton test dimensions
<Iskierka>
there are sources around for other details but they're all books so would be harder to read
<Iskierka>
oh yes, as it may not be clear: the book is citing wikipedia as its source for the 100-ton test crater diameter
<kmath>
<bofh453> @stephentyrone (I thought I had an idea but no, csqrt has a different quadrant mapping since it uses the principal… https://t.co/zDDFm89KCD
<Fiora>
lemme see if i can remember. this came up at work
<Fiora>
wait actually no are you sure?
<Fiora>
For y > 0 and not an odd integer, if x is +/-0, +0 shall be returned. <-- IEEE definition of pow
<egg|zzz|egg>
sure whereof?
<Fiora>
If x is ±0 or +Inf, x shall be returned. <-- for sqrt
<Fiora>
wow
<Fiora>
WOW
<egg|zzz|egg>
indeed
<Fiora>
sqrt(x) is not the same as pow(x, 0.5)
<Fiora>
WHAT.
<egg|zzz|egg>
hence asking the cat
<egg|zzz|egg>
Fiora: it's also inconsistent with the complex sqrt
<Fiora>
the case that hit *us* was *rsqrt*(-0)
<Fiora>
which isn't the same issue
<egg|zzz|egg>
which is consistent with sqrt tho
<egg|zzz|egg>
so it's negative infinity at -0
<Fiora>
yup. NOT NaN
<egg|zzz|egg>
indeed
<Fiora>
which is extremely weird, right? how can 1 / sqrt(x) return -inf? sqrt(x) returns positive values! and yet.
<egg|zzz|egg>
Fiora: so I can see two "sensible" values for sqrt(-0), and they are +0 and NaN (NaN is a bit annoying but justifiable as a limit of NaNs, +0 is the only real 0 that should be there)
<egg|zzz|egg>
Fiora: and yeah, this is inconsistent with both pow and powr
<egg|zzz|egg>
Fiora: also icymi I linked that book whitequark was referring to about traveling with xenon oxides on an aircraft
<Fiora>
oh fuck it's worse
<Fiora>
there's TWO places pow isn't the same as sqrt
<Fiora>
pow(-inf, 0.5) is inf????????
<egg|zzz|egg>
Fiora: yeah but you should be comparing with powr to be fair I think
<egg|zzz|egg>
Fiora: eggstremely weirder is "rootn(±0, n) is +0 for even integral n>0"
<Fiora>
is powr a thing in IEEE
<egg|zzz|egg>
Fiora: so sqrt is not rootn(_, 2)
<Fiora>
wHAT.
<egg|zzz|egg>
Fiora: yup, looking at the 2008 version
<Fiora>
For y an odd integer > 0, if x is -Inf, -Inf shall be returned.
<Fiora>
For y > 0 and not an odd integer, if x is -Inf, +Inf shall be returned.
<Fiora>
LLVM even has code for this.
<Fiora>
(I checked LLVM's conditions for optimizing pow -> sqrt in safe math)
<egg|zzz|egg>
Fiora: that doesn't seem to be something IEEE itself says tho
<Fiora>
..... does POSIX differ with IEEE?!
<egg|zzz|egg>
(IEEE 754 that is)
<egg|zzz|egg>
Fiora: that would not surprise me too much?
<egg|zzz|egg>
Fiora: otoh, IEEE recommending something weird for sqrt that's inconsistent with its own recommendations for similar functions weirds me out
<Fiora>
"This function returns the first value raised to the second power, returning the same values as the libm pow functions would, and handles error conditions in the same way."
<Fiora>
okay, so LLVM matches libm
<egg|zzz|egg>
afk a bit
<Fiora>
oh my fucking god tim murray
<Fiora>
"born to round / double is a fuck / kill em all 754 / I am denorm man / 410,757,864,530 can't be represented as a float"
<soundnfury>
double precision / may not solve your rounding woes; / Condition matters.
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<egg|cell|egg>
Fiora: i can't find a specification for what pow(-∞,1／2) does in IEEE 754-2008
<egg|cell|egg>
For finite negative x it would NaN
<egg|cell|egg>
(and non integer y that is)
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<whitequark>
powr sounds like a motorola phone codename
* Qboid
gives whitequark and UmbralRaptor a regular analemma
<Ellied>
!wpn egg
* Qboid
gives egg a technetium scream
<UmbralRaptor>
!wpn egg|work|egg && Ellied
* Qboid
gives egg|work|egg && Ellied a cryo expectation
* UmbralRaptor
? people who think Harvard is representative of US higher education.
<egg|work|egg>
!wpn Fiora
* Qboid
gives Fiora a charm motor
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<egg|phone|egg>
Bofh : hm, still no reply from the cat?
<bofh>
egg|phone|egg: atlas has shownthat sometimes he takes awhile to respond. patience ;)
<egg|phone|egg>
:-p
<bofh>
whitequark: ahh yes, the motorola powr
<egg|phone|egg>
Bofh: this confused Fiora too, see above
<bofh>
egg|phone|egg: yeah, sec
<egg|phone|egg>
Also my phone keeps switching to Italian when I type Fiora, è fastidioso
<egg|phone|egg>
UmbralRaptor: 古在！
<bofh>
LOL
<bofh>
06:57 <@Fiora> pow(-inf, 0.5) is inf????????
<bofh>
what the fuck
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<bofh>
07:07 <@Fiora> LLVM even has code for this.
<bofh>
just checked fdlibm, that special case indeed maps -Inf -> NaN, +Inf, itsself (-Inf) if y is: non-integer, odd integer, even integer respectively.
<bofh>
actually wait what the flying fuck that makes no sense whatsoever
<bofh>
oh swap even and odd
<egg|cell|egg>
That sounds reasonable?
<bofh>
I can't read.
<bofh>
egg|cell|egg: it is reasonable, once you read correctly.
<egg|afk|egg>
infinity being even
<egg|afk|egg>
bofh: wait, with Fiora and Atlas that makes two floating-point cats
<egg|afk|egg>
is everyone that does numerics a cat
<kmath>
<stephentyrone> @FioraAeterna @rygorous Unfortunately the feeling was that languages would provide it anyway, so defining the edge… https://t.co/dEIAonRGfC
<egg>
Fiora: but I'd say the weirder thing in all that is that IEEE 754 squareRoot and rootn(·, 2) are inconsistent
* Qboid
gives bofh and Fiora a Gaussian squeeze surprise
<egg>
!wpn Ellied
* Qboid
gives Ellied a code-switching thermometer
<bofh>
my favourite!
<egg>
bofh: frankly with rootn(-0, 2) = +0 whereas squareRoot(-0) = -0 I'd be inclined to think that the latter is just standardizing existing daft practice
<bofh>
egg: at this point who knows.
<egg>
bofh: but then that would mean Atlas was confused when posting on stack overflow 4 years ago, which is odd
<bofh>
yeah. huh.
<egg>
!kd -help
<Qboid>
egg: Invalid ID!
<egg>
!help kd
<Qboid>
kd: Prints out the details for Kountdown Events
<Qboid>
example: !kountdown 1
<Qboid>
parameters: -add (Add Kountdown event. Syntax: !kountdown -add name|description|time.), -list (List pending Kountdown Events or subscribers), -remove (Delete Kountdown by id.), -edit (Edits a Kountdown by id.), -subscribe (Subscribe yourself or a channel to Kountdown.), -unsubscribe (Unsubscribes yourself or a channel from the Kountdown.)
<kmath>
<FioraAeterna> i love this tweet because for 5 seconds i thought it was a bad 'splain and then my brain melted https://t.co/Qr7U7DsTg3
<UmbralRaptor>
"Applications are open for fellowships to begin in fall 2018. We anticipate offering up to 24 fellowships this year, contingent upon funding. NHFP is open to applicants of any nationality who have earned their doctoral degrees on or after January 1, 2015, in astronomy, physics, or related disciplines."
<UmbralRaptor>
!wa number of physics and astronomy PhDs awarded in 2015
<Qboid>
UmbralRaptor: Seems that Wolfram is unable to understand that.
<soundnfury>
bofh: for each precision (except for half and octuple), the IEEE specifies two floating-point types: _metric_ and _imperial_.
<soundnfury>
floating point numbers have a _sign bit_, which denotes whether the number has been cryptographically signed.
<kmath>
<bofh453> LRT: YAHTZEE!!! (tho I honestly don't think t-Butyl Hydroperoxide deserves a 4 for toxicity. 2 at best). https://t.co/Ln1eVVDRLy
<soundnfury>
bofh: of course, clearly the best way to avoid all these confusing signed-zero rules is to use a float format that's twos complement instead of s&m
<soundnfury>
(and thus have a space-of-numbers that's asymmetric about 0 ;)
<soundnfury>
in fact I've just realised how _gloriously horrifying_ that really is: 1 and -1 would have different exponents!
<soundnfury>
(1×2^0 vs -2×2^-1, because a mantissa of 100...0 is not -1 but -2)
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<bofh>
soundnfury: oops
<Fiora>
bofh: *hops back on irc* *catches up*
<bofh>
Fiora: mostly just more floating point insanity and me going thru Arkema's organic hydroperoxide list.
<bofh>
but then again I consider t-butyllithium something to be treated with respect, but fairly tame
<bofh>
(tho that's largely b/c I've played with dimethylzinc before)
<bofh>
my fav thing from the DmZn MSDS is prolly:
<bofh>
"INGESTION: highly unlikely, as liquid or vapor either ignites spontaneously or reacts with moisture to form methane and zinc oxide. Do NOT induce vomiting; immediately dilute material by giving large amounts of water or milk; if vomiting occurs, give more fluids; when vomiting ceases, milk or olive oil may be given for their soothing effect; get medical attention. (USCG, 1999)"
<bofh>
"INHALATION: highly unlikely, as liquid or vapor either ignites spontaneously or reacts with moisture to form methane and zinc oxide. Move victim to clean air and administer mouth-to-mouth resuscitation if breathing has ceased; give oxygen only when authorized by physician; keep victim warm and comfortable; call physician immediately."
<bofh>
damn. well honestly it shouldn't be hard, just hook up an arduino to USB and some solenoids controlling gasoline sprays, and then modify StepMania a bit
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<bofh>
I mean basically you want a timed mis-step to activate the corresponding flamethrower
<kmath>
<AnthonyMKreis> Black smoke from the Russian consulate in San Francisco. We'll have to wait a little longer for our next POTUS. https://t.co/76JwbiB9Ti
<UmbralRaptor>
More seriously, are they burning documents?
<kmath>
<VeraMBergen> The photo of this convo between firefighters and Russian officials saying "nothing to see here" doesn't disappoint… https://t.co/uwyvTmWHjh
<kmath>
<Kisai> @BadAstronomer @maritzac Well it's black smoke, so that means they're likely burning plastic (eg cd-rom's, SD cards… https://t.co/XIXRwFdhu2
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<Qboid>
4d 0h 0m 0s left to event #8: Intelsat 37e & BSAT 4a/Ariane 5 ECA [at 2017-09-05 21:51:00]. Say '!kountdown 8' for details
<UmbralRaptor>
Today in disappointing meals: a near-0 scoville dish with "Thai" in its name.
<kmath>
<bofh453> @Newpa_Hasai Still the only time other than blatant obvious cheating when I wished I could hand out negative marks.
<bofh>
UmbralRaptor: that *is* a disappointment.
<UmbralRaptor>
Also, owch at those students.
<icefire>
a massive pun thread is exactly what I needed after a 5 hour flight
<egg>
!wpn bofh
* Qboid
gives bofh an extradimensional atom
<egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a capybara
<bofh>
!wpn egg
* Qboid
gives egg an unremarkable cell
<bofh>
UmbralRaptor: my favourite cheating story was when I was searching online for some question and happened upon the recent queue of Ask A Topologist
<bofh>
and one of the recent questions was, verbatim, a question off this week's Real Analysis assignment, due tomorrow
<bofh>
and the person asking it used his email and real name and was in my class >_>
<bofh>
I recall thinking "really?! you're in *third year*. third year pure mathematics. what the actual fuck."