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.
<soundnfury>
!wpn egg|zzz|egg
* Qboid
gives egg|zzz|egg a proactinium gegenschein
<G-Mobile>
if you emit a photon at an imperfect reflector, what happens? is the imperfectitudinality of the reflector a representation of non-reflective imperfections in the reflector, some statistical loss in the reflection process, both?
<G-Mobile>
egg, have you considered owning more cats?
<whitequark>
egg|zzz|egg: yeah, she does it pretty well, actually
<whitequark>
what helped is taking эта хуйня by the scabbard and pointedly slapping in front of котя
<whitequark>
so she understood that she is, in fact, allowed to do that too
<egg|zzz|egg>
:D
<egg|zzz|egg>
!wpn bofh
* Qboid
gives bofh a lead diprotodon
<soundnfury>
!wpn egg|zzz|egg
* Qboid
gives egg|zzz|egg a sonic screwdriver/compactification hybrid
<soundnfury>
ah! both can be used to solve contrived problems in unexplained ways!
APlayer has joined #kspacademia
<bofh>
touché
<APlayer>
Uh, I may need some help
<APlayer>
Some may remember when I was working on a tool to simulate low thrust maneuvers and you guys taught me that RK4 is a thing...
<APlayer>
Now, for RK4, I need a t0 and a t1, right? That is, t1 has to be defined, or may I omit that?
<egg|zzz|egg>
bofh: so that spike in Vall's spectrum near Bop doesn't seem to be a resonance with anything else that I can see Ꙩ_ꙩ
<egg|zzz|egg>
but then I'm also seeing nothing at 2 tylo periods = 5 vall periods in the spectra?
<egg|zzz|egg>
bofh: oh, there's a lot of 4/φ weirdness in those spectra, that laythe/vall weird spike is 4/φ from the spike in vall's spectrum near bop...
<bofh>
heh. next time, don't cram a φ into your orbital elements :P
<UmbralRaptor>
Use a more safely transcendental number?
<UmbralRaptor>
APlayer: t1 is the time you're finding the values for and t0 is the tine you already know them, I assume? Notation varies. But if I'm correct, t1 is just t0 plus your time step.
<UmbralRaptor>
Greys: blarg, everything I did with reflection was purely classical. >_>
<APlayer>
t0 is the time when the simulation starts, t1 is the time when the simulation ends.
<UmbralRaptor>
That makes t1 sound unnecessary.
<APlayer>
Okay, that solves my problem. Thanks!
<UmbralRaptor>
Though for testing, you probably wan it to stop after a few tinesteps?
<UmbralRaptor>
*timesteps
<soundnfury>
Greys: at least for radio waves reflecting off metal, I believe the loss is in the form of resistive heating in the reflector (due to the evanescent-wave currents flowing therein)
<soundnfury>
optical frequencies may be more complicated, because the wavelength is small enough for Weird Quantum Shit™ to happen with the atoms of the reflector
<UmbralRaptor>
It's possible that properly quantum stuff is more a feature of xray optics.
<soundnfury>
well, quantum stuff with the atom size near λ is an xray thing, but quantum stuff with electron jumps near hf is a feature of visible-light optics
APlayer has quit [Ping timeout: 204 seconds]
<egg|zzz|egg>
bofh: well why is φ such a bad choice though, doesn't its continued fraction make it the best choice to prevent resonances?
<bofh>
erm, I was under the impression resonances are *desired* :P
<bofh>
it's not a bad choice if you explicitly want to prevent them
<egg|zzz|egg>
bofh: not really
<bofh>
tho now I'm curious how something transcendental would fare instead
<egg|zzz|egg>
bofh: the galilean moons suggest that of course, and that's why the devs (well nova) went with 1:2:4
<bofh>
(but not π for obvious reasons
<bofh>
+)*
<egg|zzz|egg>
but jool is a couple of orders of magnitude too light
<egg|zzz|egg>
the resonance destabilizes things
<bofh>
what's jool's GM?
<egg|zzz|egg>
UmbralRaptor: you remember numbers iirc
<egg|zzz|egg>
bofh: hm, I'd need to compute the spectra absent bop, or with 2:5 resonances instead of 1:4ф dissonances to see how things change...
<egg|zzz|egg>
so many simulations to run
<egg|zzz|egg>
s/4φ/4\/φ/
<SpreadsheetRaptor>
Bop is actually an insect.
<egg|zzz|egg>
!u фφ
<Qboid>
U+0444 CYRILLIC SMALL LETTER EF (ф)
<Qboid>
U+03C6 GREEK SMALL LETTER PHI (φ)
<SpreadsheetRaptor>
Also, ow at Laythe.
<egg|zzz|egg>
argh so many keyboald layouts
<egg|zzz|egg>
SpreadsheetRaptor: ah yes it does get high-frequency
<bofh>
it's the innermost moon, so that makes sense
<egg|zzz|egg>
bofh: thing is φ itself has a messy continued fraction of course, but 4/φ has a fairly good convergent with 5/2
<soundnfury>
yeah, you want something that's just not near any small-number ratios or products thereof. √2 is surprisingly good for that (cf. wolf fifth)
<Ellied>
Easy: Use Google's network location service. Hard: Replace it with a third-party middleware and backend that uses Mozilla's location service. Ellie: Carry around a 5 GB database of every known cell tower in the world.
<bofh>
egg|zzz|egg/soundnfury: you'll still hit one eventually, the rationals are dense in the reals after all.
<egg|zzz|egg>
bofh: the question being how early, 2 and 5 are still fairly smol numbers
<soundnfury>
yeah see φ:1 sounds like a slightly sharp minor sixth, whereas √2:1 sounds like the actual devil
<soundnfury>
(the best intonation I've been able to find for it is 45/32)
<soundnfury>
egg|zzz|egg: maybe you should have used Farey sequences.
<egg|zzz|egg>
soundnfury: what about 7/5 for √2?
<soundnfury>
that's not quite as close
<soundnfury>
but point taken
<soundnfury>
that _is_ the interval between a justly intoned major third (5:4) and minor seventh (7:4), which _is_ six semitones.
<egg|zzz|egg>
soundnfury: and even failing that you have the next convergent, 17/12, and here you're getting really close
<soundnfury>
egg|zzz|egg: yes but 17 isn't a number
<egg|zzz|egg>
:D
<soundnfury>
(at least as far as musical intonation is concerned :P)
<soundnfury>
I mean, you show me a string or pipe playing its 17th harmonic
<bofh>
Ellied: where does one get this 5GiB database?
<egg|zzz|egg>
!wpn bofh
* Qboid
gives bofh a hafnium ?
<bofh>
*a* hafnium? like are we talking 1 atom, 1 mol, what?
<egg|zzz|egg>
bofh: it says a hafnium ?, is the ? not rendering for you?
<soundnfury>
!u ?
<Qboid>
U+1F4A9 PILE OF POO (?)
<egg|zzz|egg>
bofh: also, still no news from atlas on rootn vs squareRoot?
<bofh>
ahh. yeah, it inexplicably failed to render here. *glares at fonts on this machine*
<Ellied>
bofh: OpenCellID and Mozilla. F-Droid has a "Local GSM" location backend for microg that will download from both.
<Ellied>
(for the former you need to give them your name and email for an API key)
<Ellied>
so "every known cell tower in the world" is a stretch to say the least, but they at least appear to have quite good coverage in major population centers.
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<bofh>
tbh I just use gps, but this is still useful info to have
<Ellied>
I spend a lot of time inside buildings, and for some reason it doesn't seem to want to save GPS data for last-known-position stuff
<egg|zzz|egg>
!wpn u
* Qboid
gives u a serpentine radius
<egg|zzz|egg>
um
<egg|zzz|egg>
!wpn SpreadsheetRaptor
* Qboid
gives SpreadsheetRaptor a radon surjective bomb
<Ellied>
There is also a backend that will use GPS data to maintain a local database of wifi networks for location
<Ellied>
that is, wifi AP BSSIDs.
SpreadsheetRaptor is now known as UmbralRaptor
<UmbralRaptor>
attwifi location: everywhere
<egg|zzz|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a postorder pharmacy/ideal hybrid
<Ellied>
UmbralRaptor: well, that's why I corrected myself to BSSIDs, because it's keying in on the individual broadcast stations instead of the whole network.
<UmbralRaptor>
!wpn egg|zzz|egg
* Qboid
gives egg|zzz|egg a Sturm-Liouville license
<UmbralRaptor>
Ellied: ah
<Ellied>
I don't know if it actually triangulates or just assumes "hey, I can see that one, I must be within a few meters of it"
<soundnfury>
egg|zzz|egg: if I drop you in a lake, do you become an œ?
<Ellied>
UmbralRaptor: so, another step towards understanding trans health care as well as 1930s Germany did?
<UmbralRaptor>
Something like that.
<egg|zzz|egg>
!wpn котя
* Qboid
gives котя a praesiodymium homomorphism
<egg|zzz|egg>
!wpn whitequark
* Qboid
gives whitequark a cone
<UmbralRaptor>
Ellied: though hopefully without the destruction of records part this time. =S
<UmbralRaptor>
!wpn egg|zzz|egg
* Qboid
gives egg|zzz|egg a basilect
<Ellied>
Hopefully.
<Ellied>
Granted, destroying records is considerably harder in the modern age than it was back then.
<Ellied>
All they had to do was set a library on fire and it was over. Nowadays most records are not only multi-site-redundant, but also often stored on media with a better-than-even chance of surviving a building fire.
<Ellied>
OTOH, destroying data from said media can now be accomplished in a very short time and can be initiated remotely. :I
<Ellied>
I keep thinking about those EPA climate scientists who started backing up all the climate data they could reach onto personal drives a year or so ago in case the administration decided to order its destruction.
<egg|zzz|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a nefarious cow
<egg|zzz|egg>
!wpn Ellied
* Qboid
gives Ellied a symmetric spiral cut product
<egg|zzz|egg>
!wpn rqou
* Qboid
gives rqou a trihexaflexagon
<rqou>
!wpn egg|zzz|egg
* Qboid
gives egg|zzz|egg an arsenic overclocked † which vaguely resembles a banana
<egg|zzz|egg>
rqou!
<egg|zzz|egg>
rqou: did the eggsplanation make some amount of sense
<UmbralRaptor>
"nefarious cow" sounds very Swiss.
<rqou>
somewhat
<soundnfury>
UmbralRaptor: the nefarious cow is being observed through a sneaky telescope
<soundnfury>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor an Ebers-Moll torpedo
<UmbralRaptor>
!wpn soundnfury && egg|zzz|egg
* Qboid
gives soundnfury && egg|zzz|egg a gregarious polytrope
<egg|zzz|egg>
rqou: so <egg|zzz* = (zzz|egg>)*
<rqou>
er, so i vaguely know that the QM bra and ket notation is somehow related to adjoints and/or dual spaces, but i don't know anything beyond that
<egg|zzz|egg>
rqou: so, typically you write the inner product of vectors v and w <v,w>
<egg|zzz|egg>
rqou: sometimes you might see the notation <v|w>
<egg|zzz|egg>
rqou: now, <v|.> (. being a placeholder) is a linear function that returns a scalar, aka an element of the dual
<egg|zzz|egg>
and then you can apply it to a vector w and get <v|w>
<soundnfury>
egg|zzz|egg: "linear form"
<egg|zzz|egg>
yes I know soundnfury
<egg|zzz|egg>
rqou: the physicists write <v| for <v|.>, and then |w> for a vector w
<soundnfury>
(I thought I'd mention it in case that was what he knew it as)
<egg|zzz|egg>
good point
<egg|zzz|egg>
rqou: so then <v| applied to |w> is <v|w>, which is a fairly neat notation
<egg|zzz|egg>
rqou: now say you have a matrix (linear endomorphism, whatever) A; you can multiply A and w, instead of writing that Aw you write it A|w> since you call your vector |w>
<soundnfury>
(if you're a co-ordinates thinker like me, <v| is just vᵀ)
* egg|zzz|egg
throws soundnfury in an infinite-dimensional vector space without the axiom of choice
* soundnfury
stabs egg|zzz|egg with a lemon
<egg|zzz|egg>
or v*, we're in a Hilbert space (or v dagger depending whether you're feeling stabbity)
<egg|zzz|egg>
well <v| = |v>* really
<soundnfury>
egg|zzz|egg: we're _always_ feeling stabbity in here
<egg|zzz|egg>
rqou: anyway, the nice thing with that is that you can use an arbitrary matrix as your bilinear form and it looks like you're using a bilinear form: <v|A|w>, which means v* A w, but it clearly looks like we're doing a bilinear thing, whereas v* A w has this weird asymmetry
<egg|zzz|egg>
(the proper thing to do would be to not use an endomorphism as a bilinear form of course, and to say that A is a bilinear form that you apply to v and w, A(v,w), but then the coordinated people get annoyed
* UmbralRaptor
stabs soundnfury with an orange.
<egg|zzz|egg>
or we could use Einstein notation and indices)
<rqou>
so one thing that seems a bit weird: if <v| is supposed to be a linear functional, what basis is used to turn it into a vector of numbers?
<egg|zzz|egg>
rqou: you don't need a basis, just an inner product
<egg|zzz|egg>
the inner product turns v=|v> into <v|, by saying <v| = <v|,.>
<rqou>
right, but then there is that "<v| is just vᵀ" thing
<egg|zzz|egg>
that's because ᵀ is just that
<egg|zzz|egg>
you don't need a basis to transpose
<rqou>
i thought transpose is supposed to take a vector and give me a new vector, but the inner product takes a vector and gives me a function
<egg|zzz|egg>
you merely need an inner product, vᵀ = <v,.>
<SnoopJeDi>
rqou, it's perhaps more accurate to say that the transpose is the operation egg|zzz|egg is describing
<egg|zzz|egg>
rqou: a row vector is a linear functional
<SnoopJeDi>
i.e. tranposition as she is taught is not the more fundamental concept
<egg|zzz|egg>
rqou: or rather it's the coordinates of a linear functional
<soundnfury>
UmbralRaptor: but Zorn doesn't have an orange!
<rqou>
ah ok
<egg|zzz|egg>
rqou: now, in coordinates vᵀ(in the turn the vector sense) = <v,.> is true only taking the inner product which is consistent with the coordinates
<egg|zzz|egg>
rqou: which you probably know you can compute as <v,w>=vᵀw
<soundnfury>
rqou: if you do want a co-ordinate thinking: (<v|e_x>, <v|e_y>, <v|e_z>)
<egg|zzz|egg>
rqou: (and there it's quite obvious that vᵀ = <v,.> since <v,w>=vᵀw right)
<soundnfury>
that's how you turn a linear form into a row-vector with a basis
<rqou>
but that only works if you're using the standard inner product, right? not some weird one just for lulz
<kmath>
<stephentyrone> Twitter truly does not understand its audience. https://t.co/NVk2cy2G80
<egg|zzz|egg>
rqou: if you're using an inner product that's inconsistent with your coordinates, then you shouldn't be using the transpose that comes from your coordinates :-p
<egg|zzz|egg>
(or at least you should be careful)
<soundnfury>
I think it works as long as your inner product distributes?
* soundnfury
shrugs
<egg|zzz|egg>
rqou: say you're using some other inner product which, in your coordinates, is computed as <v,w>_B = vᵀBw; then in those coordinates, the linear functional induced by <.,.>_B from v is vᵀB
<rqou>
ah i see
<egg|zzz|egg>
rqou: but let's say you can go to <.,.>_B-orthonormal coordinates with the matrix A: (Av)ᵀ(Aw)=vᵀBw (so that B=AᵀA), then in those coordinates the transpose is as above, and in fact to get the B-transpose of v, you go to those coordinates, get Av, transpose, (Av)ᵀ=vᵀAᵀ, and now use the coordinate transformation for row vectors to go back, vᵀAᵀA)