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.
<whitequark>
sounds too real
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<UmbralRaptop>
I think the IoT sextoy with hard coded credentials already happened a few years ago?
<kmath>
<hfalcke> Ever wondered about the quality of some Elsevier journals ? They ask a radio astronomer to review a paper on air po… https://t.co/Z4YJTYfMyO
<bofh>
SnoopJeDi: now I want to find some surplus beer barrels and convert them into VHF cavity duplexers.
<SnoopJeDi>
👍
<SnoopJeDi>
I asked a mean question today to the head of the US magnet development program, after his talk about the FNAL efforts to build a 4-layer cosθ Nb3Sn magnet
<SnoopJeDi>
basically "cosθ is expensive, do you forsee any way to attack the cost problem in this, or are we resigning ourselves to paying 2X (or more) for these magnets?"
<SnoopJeDi>
answer was basically "who cares about cost let's build it first and then it'll magically become cheap" yea man like exactly what happened with LHC's dipoles 🙄
<SnoopJeDi>
left: shitload of metastasized prostate cancer, middle and right: after one/two treatments with 226-Ac (cc whitequark)
<SnoopJeDi>
err, 225-Ac
<SnoopJeDi>
(apparently one of the very underexplored radioisotopes because it's difficult to produce, but TRIUMF is interested in developing a programme for it)
<bofh>
SnoopJeDi: rofl
<bofh>
that's incredible re: the Nb3Sn magnet
<SnoopJeDi>
yea 4 layers is
<bofh>
(also obligatory "why not use YBCO-123 chilled to 4.2K - 20K" comment goes here)
<SnoopJeDi>
fuckin nuts
<SnoopJeDi>
it's not even 4 uniform layers
<bofh>
(that stuff has insanely high critical current densities and I think in accelerator magnets you want large blocks anyhow)
<SnoopJeDi>
it's graded, and I *think* it's 2 or 3 different types of Rutherford cables
<SnoopJeDi>
yea that was something like his answer, that you can treat it analytically and you need so-and-so thickness, period, so no not really a way to make it cheaper
<bofh>
also holy fuck that cancer radiotherapy
<SnoopJeDi>
I don't find that satisfactory, though
<SnoopJeDi>
not that it matters
<SnoopJeDi>
FNAL is truly leading with their *canted* cosθ
<SnoopJeDi>
which is like normal cosθ but crazier
<SnoopJeDi>
(it's tilted in the axial direction and the windings cancel each other out...?)
<egg|laptop|egg>
bofh: arguably 9.2 only has correctness of the inexact exception as a "should", whereas invalid operation is a "shall"
<egg|laptop|egg>
bofh: but still, correct rounding and exactness checking would be better :-p
<egg|laptop|egg>
bofh: yes, most dead beefs are quiet
<egg|laptop|egg>
bofh: "most dead beefs are quiet" << that's actually true, because 0x7FFD'EADB'EEF0'0000 is quiet :-p
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<egg|laptop|egg>
(assuming you use the preferred encoding for quietness described in 6.2.1)
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<egg|cat|egg>
!seen awang
<Qboid>
egg|cat|egg: I haven't seen the user awang yet.
<egg|cat|egg>
hm the "cannot be null" thing got fixed?
<egg|cat|egg>
!wpn Thomas
* Qboid
gives Thomas a Givens git
<egg|cat|egg>
!wpn bofh
* Qboid
gives bofh a dual basilect
<APlayer>
!wpn egg|cat|egg
* Qboid
gives egg|cat|egg an isobaric GIF
<egg|cat|egg>
!wpn APlayer
* Qboid
gives APlayer a ruby chisel
<APlayer>
Oh, shiny!
<UmbralRaptop>
!wpn egg && APlayer
* Qboid
gives egg && APlayer an actinium pigeon
<APlayer>
Now me and a cat-egg hybrid share one pideon
<APlayer>
pigeon*
<APlayer>
!wpn UmbralRaptop
* Qboid
gives UmbralRaptop a Grothendieck 🚀 which vaguely resembles a ruby
<UmbralRaptop>
Until the pigeon decays.
<APlayer>
What was first, the egg or the pigeon? Or was the egg eaten by human, or was the pigeon eaten by cat?
<bofh>
egg|cat|egg: wait, branching for NaN handling? a NaN fed into a householder routine will retu4n a NaN simply via propagation...
<UmbralRaptop>
!wpn -add:wpn robin
<Qboid>
UmbralRaptop: Weapon added!
<APlayer>
Which reminds me. Are actual weapons in the wpn database? Such as swords, spears, chain mail and similar
<UmbralRaptop>
Yes. But egg happened.
<egg|cat|egg>
meow
<egg|cat|egg>
bofh: yes, but see the comment
<egg|cat|egg>
bofh: you end up signaling overflows, also invalid because comparisons, also producing other NaNs from doing things to your overflows, and not preserving the payload
<egg|cat|egg>
with a decent predictor this branch is free anyway :-p
<egg|cat|egg>
APlayer: wpn is Ellied's idea originally
<egg|cat|egg>
and it instantly got weird things in it because egg
<APlayer>
Heh
<bofh>
egg|cat|egg: is there literally *anything* that wpuld care about the payload contents of a NaN fed to a transcendental f'n?
<egg|cat|egg>
bofh: I don't know, but IEEE says I shall return one of the input NaNs, I don't make the rules :-p
<egg|cat|egg>
bofh: honestly I have never seen NaN payloads used :-p
<bofh>
egg|cat|egg: I think one of the Mozilla JS interpreters uses them.
<egg|cat|egg>
bofh: O_o what for
<egg|cat|egg>
bofh: also is there something that uses sNaNs
<egg|cat|egg>
bofh: OK it's actually just should be one of the input NaNs, not shall
<egg|cat|egg>
bofh: but there's a shall requirement on being quiet when given a quiet NaN
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<egg|cat|egg>
!wpn UmbralRaptop
* Qboid
gives UmbralRaptop a brushless Minkowsky electron
<UmbralRaptop>
uh
<bofh>
egg|cat|egg: what exactly is the difference in behaviour of sNaN vs. qNaN?
<egg|cat|egg>
bofh: sNaNs get turned to qNaNs by most things, signaling the invalid operation exception in the process (whereas a qNaN does not signal the invalid operation exception)
<egg|cat|egg>
bofh: there's also some blurb about the purpose: qNaNs "should [...] afford retrospective diagnostic information inherited from invalid or unavailable data and results", sNaNs "afford representations for uninitialized variables and arithmetic-like enhancements"
<egg|cat|egg>
bofh: where they cite complex affine infinities and eggstremely wide range as eggsamples of those "enhancements"
<egg|cat|egg>
bofh: so I guess the idea is that you catch the invalid operation exception and then interpret your sNaNs to give an enhanced result
<egg|cat|egg>
bofh: so unsurprisingly switching to our cube root, which changes a couple of ULPs in the interpretation of orbits, massively changes the behaviour of the (unretrobopped) stock system :D
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<Ellied>
APlayer: twitter.com/diodebot also uses the wpn database (or an older snapshot of it, rather)
<bofh>
egg|cat|egg: that *is* surprising actually, b/c it implies a degree of sensitivity of those orbits that I wasn't expecting.
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<bofh>
like I wouldn't be surprised if the behaviour of Pol and Retrobop changed since rofl, but isn't the stock system (nominally) ~stable?
<bofh>
also I need to actually properly look at this code (holy fuck I have been too busy lately :/)
<UmbralRaptop>
Stock is grossly unstable.
<UmbralRaptop>
IIRC, they messed up the resonance.
<APlayer>
Ellied: Ah, got it. You guys really like fooling around with the wpns! :D
<APlayer>
Speaking of fooling... On April the 1st, !wpn should be limited to handing out fluffy cats! :-)
* UmbralRaptop
gives APlayer a floofy cat which clearly resembles a cat.
* APlayer
gives UmbralRaptop a floofy kitty which clearly resembles a feathery kitty
<APlayer>
One thing I still don't get... Why are planets/moons in resonance stable?
<egg|cat|egg>
bofh: well the moons of the Jool system are the interesting part
<UmbralRaptop>
Depends on the resonance.
<UmbralRaptop>
But AIUI, small perturbations result in forces that push the planets/moons back.
<APlayer>
Well, I also guess "stable" is not a mere yes/no thing.
<UmbralRaptop>
On the other talon, the Kirkwood gaps are resonances with Jupiter.
* APlayer
appreciates "On the other talon"
<Ellied>
a few years ago on april fool's, icefire made kmath do !wpn in response to ;mission
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* APlayer
gives UmbralRaptop a sphere of protons as dense as water with a radius of 168.5
<APlayer>
m
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* egg|cat|egg
pets a cat
<egg|cat|egg>
bofh: the new cbrt makes tylo escape after the early tylo-vall encounter in stock :D
<egg|cat|egg>
(with the old one, only vall escaped)
<bofh>
which of those two is more correct, dynamically speaking?
<bofh>
(I get the feeling "neither escapes" is correct since after that encounter they should both still remain gravitationally bound to their star...)
<egg|cat|egg>
bofh: escapes the jool system that is
<egg|cat|egg>
bofh: and which one is correct is a question devoid of meaning
<egg|cat|egg>
bofh: the wise wolf bowed his head solemnly and spoke: "theres actually zero difference between correct & incorrect roundings."
<egg|cat|egg>
bofh: the step should probably be massively reduced to get locally sane simulation in those close encounters, but since it's a matter of ULPs on the initial conditions anything goes
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<egg|cat|egg>
!wpn whitequark, котя, and the котяchrome kitten
* Qboid
gives whitequark, котя, and the котяchrome kitten a tweet with a DIAC attachment
<UmbralRaptop>
Also, consider tidal deformation, etc. >_>
<egg|cat|egg>
yes
<egg|cat|egg>
also the cat stole my armchair
<egg|cat|egg>
!wpn bofh
* Qboid
gives bofh a compressed scream which strongly resembles a beaker
<bofh>
egg|cat|egg: what I'm saying is both should remain gravitationally bound to the jool system :P
<egg|cat|egg>
bofh: but why
<bofh>
oh wait no in theory two planets interacting can give enough ∆v to eject one or both out of it
<bofh>
which is strange as you wouldn't expect that to have enough energy but it can.