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.
<rqou> i guess another major question would be: "If you were to start over and explain what they're trying to do here, how would you explain it?"
<egg|zzz|egg> if I understood what the hell they're trying to do maybe I could answer that question
<egg|zzz|egg> the problem being that for you to explain that to me you'd have to understand this stuff sufficiently to teach it, at which point there'd be no need for my eggsplanations :D
<rqou> lol
<egg|zzz|egg> lemme try to stare at one slide
<rqou> unfortunately, afaict one central goal of this class's abuse of notation is "make it easier to shove into matlab"
<rqou> hence the 6x1 vectors
* egg|zzz|egg tries to keep ignoring the v_qB since it seems particularly daft
<egg|zzz|egg> but at least the vqA seems to make sense
<rqou> yeah, i just don't intuitively "get" v_qB
<egg|zzz|egg> well it's vqA
<egg|zzz|egg> except you use coordinates that rotate, but it's vqA and you have a stupid time-dependent basis
<rqou> it seems to me like it's "we somehow know we're moving, and we tried to write how we're moving in our own reference frame"
<rqou> but if there's no outside reference, idk how you're supposed to no that you're moving?
<egg|zzz|egg> don't try to make more sense out of it than that, it makes no sense
<rqou> *know
<egg|zzz|egg> it is at best a convenience so you can have all your things in the same basis, at worst a good way to shoot yourself in the foot by mixing reference frames
<rqou> also, i just realized that the B frame is non-inertial (in the physics sense)
<rqou> so i guess that's how you can detect that something is moving? :P
<rqou> i actually legitimately don't know how to do physics in non-inertial frames because i never had to learn that :P
<rqou> it's weird how we seem to be conflating "change of basis" and "actually transformed space"
<egg|zzz|egg> do not try to make sense of the vqB for it is the same vector as vqA, except the choice of basis is daft and time-dependent
<rqou> but in the example, the coordinates/numbers of vqB are simpler than vqA
<egg|zzz|egg> thou shalt not use the vqB, thou shalt strongly type thy reference frames
<egg|zzz|egg> thou shalt not work in co-ordinates
<egg|zzz|egg> co-ordinates are the destruction of the abstractions
<rqou> i see
<rqou> so how do i use not-coordinates?
<rqou> i have to somehow assign numbers to something, right?
<egg|zzz|egg> nah who needs those :-p
<rqou> who needs numbers?
<egg|zzz|egg> eggsactly
<rqou> well, unfortunately i need numbers because i've got actual robots made of actual motors and electronics and stuff
<rqou> not just made up of equations
<rqou> although i had a friend who was a physics major with an emphasis on astrophysics explaining to me how astrophysicists use weird normalized units
<rqou> so once they've solved some equations, you can't actually use any of the results
* egg|zzz|egg pages UmbralRaptor for astrophysics
<rqou> somebody has to take the answer and re-solve it with more-usable units if they want to actually look in the sky and see something
<egg|zzz|egg> rqou: ok so let's start with SO(3) so we need only vectors and not affine spaces
<rqou> sure
<egg|zzz|egg> rqou: you have an ideal omnidirectional joint whence emanates an arm (a literal arm, that ends with a hand, so we can figure out its orientation), and you're interested in the degrees of freedom of that hand
<egg|zzz|egg> so you get SO(3)
<egg|zzz|egg> rqou: expressed in the coordinates of the hand, the position of the hand is at (0 orthogonal to the arm and thumb, 0 along the thumb sticking out, 1 down the arm)
<egg|zzz|egg> (that's how I define arm coordinates if you will)
<rqou> so the origin is at the rotation axis?
<rqou> and then the hand is at 1?
<egg|zzz|egg> yeah
<rqou> ok
<egg|zzz|egg> (or alternatively there's no origin and we just have vectors, abstractly)
<egg|zzz|egg> (so the origin is absolute and common to all chosen coordinate systems)
<rqou> how can you pin down the hand with just vectors?
<egg|zzz|egg> (because I want to just deal with SO(3))
<rqou> ooh right because it's only SO(3) that's fine
<egg|zzz|egg> rqou: the hand is pinned down at the origin, which contrary to the real world where all positions are the same thing, is a magical absolute which is 0, independently of the coordinates
<egg|zzz|egg> (i.e. I planted a flag somewhere, said it's the origin, and by doing that turned your affine space into a vector space; I didn't give a canonical basis, so you only have a vector space, not triples of numbers)
<rqou> ok
<rqou> you really hate coordinates don't you? :P
<egg|zzz|egg> they're for talking to your motors, not for doing calculations
<rqou> sure
<bofh> "The introduction of a coordinate system to geometry is an act of violence." —Hermann Weyl
<bofh> :P
<egg|zzz|egg> rqou: expressed in some other coordinates (let's say the equator and equinox of J2000 to amuse UmbralRaptor), the coordinates of the arm are R(t) (0 middle finger 0 thumb 1 index)
<egg|zzz|egg> rqou: note that R(t) is a thing that changes the coordinate system, so if you want to talk types it takes a vector-of-the-hand-kind to a vector-of-the-ircf-kind
<egg|zzz|egg> they live in different vector spaces really
<egg|zzz|egg> it's not an endomorphism
<rqou> hmm, why not?
<egg|zzz|egg> you can't add the things (well you can, but then you have to put your coordinate changes back in, and then it's nicer if you just say that you have different spaces)
<egg|zzz|egg> rqou: well because we have coordinates (although we hid them)
<egg|zzz|egg> rqou: so the thing is R doesn't do anything conceptually, it takes a vector and... returns the same vector?
<egg|zzz|egg> rqou: so to sort that out, you can split the two: you have the space of vectors-in-hand-coords, and the space of vectors-in-icrf-coords
<rqou> ah, so it's _not_ "actually moves a point from one place to another"
<egg|zzz|egg> rqou: you can add vectors in hand coords by adding the tuples of numbers that underlie them in the implementation, and vectors in icrf coords similarly
<egg|zzz|egg> but you can't add vectors<hand> to vectors<icrf>
<rqou> right
<egg|zzz|egg> (because if you added the numbers you'd be doing nonsense)
<egg|zzz|egg> you need a coordinate change, and by virtue of having distinguished the spaces, that's an actual homomorphism that you *need* to apply in order for the operation to even make sense
<egg|zzz|egg> always distinguish things
<egg|zzz|egg> by giving them names
<egg|zzz|egg> name your ignorance
<rqou> so when i'm doing "herp derp i haz a computer doing 3d graphics or something" i like to think of the transformations as "actually moves points" but i suppose that's not accurate
<egg|zzz|egg> I find that extremely misleading
<rqou> it's a good way to cause "why is my screen black" though :P
<egg|zzz|egg> (whereas if you think of them as converting things it's safer)
<egg|zzz|egg> (it's literally safer if you go out of your way to use the type system to check that you're not adding vectors in different coords)
<egg|zzz|egg> rqou: so, R(t) is a kinda weird animal, it maps vector<hand> to vector<icrf>, and it's "a rotation"; what does taht mean since the source and target spaces differ?
<egg|zzz|egg> well both the source and target spaces have inner products
<rqou> hmm, so if i were writing a vidya, "running the physics engine" --> "actually moves points" and "doing rendering" --> "just renames vectors" would be a better way to think about it?
<egg|zzz|egg> rqou: and even "actually moves things" can sometimes better be described as "let's go to the reference frame where this doesn't move, and go back a bit later"
<egg|zzz|egg> (if you have something that rotates it falls into place nicely that way)
<egg|zzz|egg> but yes, physics tend to move things
<rqou> but rendering doesn't
<egg|zzz|egg> eggsactly
<egg|zzz|egg> (yes principia has rendering code now, because it is growing to have everything)
<egg|zzz|egg> bofh: eventually we'll run principia on a multivac...
<egg|zzz|egg> rqou: so, back to "what does it mean to be a rotation", or rather let's start with being an orthogonal map, it means that if you take the inner product, it's the same as if you rotate, then take the inner product in the new coords.
<rqou> right, that was the original definition from the dark ages of lecture 1 or so :P
e_14159 has quit [Ping timeout: 204 seconds]
<egg|zzz|egg> rqou: let's call our two vector spaces VH and VI, Q:VH->VI is orthogonal if for all v,w in VH, <v,w>_VH=<Qv,Qw>_VI
<egg|zzz|egg> note that I subscripted my inner products (in programmer speak, I didn't overload), to make it clear that they're in different spaces
<egg|zzz|egg> rqou: now for being a rotation, you also need to preserve orientation, and that's tricky to define (if you're from a space to itself you use the determinant, but we're between spaces, so you really need to define orientation and let's not go there)
e_14159 has joined #kspacademia
<rqou> ooh right i forgot we did that by handwaving it :P
<egg|zzz|egg> rqou: conceptually, a change of coords that's a rotation is one that doesn't go from a right hand basis to a left hand one
<egg|zzz|egg> rqou: and that's also a case where you really want to think of things as "converting the vector" rather than "moving the vector", because few reasonable motions turn your left hand into your right hand, whereas you do that all too much in graphics
<egg|zzz|egg> but alright, we have R(t), and qI(t) = R(t)(qH), all good. Now what the hell is qI'(t)? in coordinates it's clear that you're differentiating a rotation, so an angular velocity will pop up; however formally we don't have a Lie group here (you can't compose a rotation VH->VI with another one), and I have confused myself.
<egg|zzz|egg> bofh: any idea what kind of object this should be? it seems that this is elementary differential geometry but I'm not awake
<egg|zzz|egg> bofh: rqou: the answer probably lies within this comment with some unpacking https://github.com/mockingbirdnest/Principia/blob/e36821709a5ce4ffe3350e7098f3bea93bf7ff52/physics/rigid_motion.hpp#L56-L59
<Ellied> egg: I just tried, and Rust does not appear to produce the classic floating-point rounding errors for simple thing like 0.2+0.1 and 1/3+1/3+1/3 (0.3 and 1.0, respectively). does it apply some kind of correction for trivial cases like this, or what?
<bofh> ugh. *something* on the tangent bundle? I actually forget.
<rqou> Ellied: isn't it just because Rust uses a Dragon-like "minimum digits" algorithm to print floats?
<Ellied> I wouldn't know, I'm relatively new to this
<egg|zzz|egg> Ellied: try equality-comparing things
<egg|zzz|egg> printing numbers should be done with care and not trusted otherwise for last few bits trickery
<Ellied> I did, it passes. 1.0/3.0 + 1.0/3.0 + 1.0/3.0 == 1.0 is true
<egg|zzz|egg> uh
<egg|zzz|egg> stupid hexchat
<egg|zzz|egg> !csharp 1.0/3.0 + 1.0/3.0 + 1.0/3.0 == 1.0
<Qboid> true
<egg|zzz|egg> that might be because it's true?
<Ellied> I thought the classic case of fp rounding errors would have the left-hand statement equal 0.99999999999999 or something
<Ellied> !csharp 0.1+0.2 == 0.3
<Qboid> false
<Ellied> yeah, that's true in Rust
<rqou> constant folding might be done with arbitrary precision?
<egg|zzz|egg> ^ possibly
<Ellied> ah, so it might produce errors if they're assigned to variables first?
<rqou> also, i just had a thought...
<rqou> !csharp System.Environment.OSVersion
<Qboid> Unix 4.4.0.31
<Ellied> huh, I assigned a = 0.1f32, b = 0.2f32, and c = 0.3f32, and a+b == c is true
<rqou> !csharp System.Threading.Sleep(1000000000)
<Qboid> (1,19): error CS0234: The type or namespace name `Sleep' does not exist in the namespace `System.Threading'. Are you missing an assembly reference?
<rqou> aw :(
<Ellied> ohh, if I don't declare the types explicitly with suffixes then it's false
<egg|zzz|egg> rqou: stop trying to break Thomas's bot
<rqou> lol
<Ellied> curious
<egg|zzz|egg> !csharp 0.1f+0.2f==0.3f
<Qboid> false
<UmbralRaptor> egg|zzz|egg: Why stop? Because Qboid doesn't know where the WMDs are?
<egg|zzz|egg> rqou: Ellied: things seem to differ as expected? https://godbolt.org/g/CXdNDx
<egg|zzz|egg> (1 ULP)
<rqou> hmm are lambdas enabled in the bot?
<rqou> !csharp () => { return 42; }
<Qboid> (1,2): error CS1660: Cannot convert `lambda expression' to non-delegate type `object'
<rqou> !csharp () => { return 42; }()
<Qboid> (1,21): error CS1525: Unexpected symbol `(', expecting `;'
<rqou> !csharp (() => { return 42; })()
<Qboid> (1,2): error CS0119: Expression denotes a `anonymous method', where a `method group' was expected
<rqou> apparently i can't c#
<egg|zzz|egg> !csharp rqous_own_method=() => { return 42; };
<Qboid> (1,2): error CS0103: The name `rqous_own_method' does not exist in the current context
<egg|zzz|egg> !csharp var rqous_own_method=() => { return 42; };
<Qboid> (1,2): error CS0815: An implicitly typed local variable declaration cannot be initialized with `anonymous method'
<egg|zzz|egg> !csharp Action rqous_own_method=() => { return 42; };
<Qboid> (1,34): error CS8030: Anonymous function or lambda expression converted to a void returning delegate cannot return a value
<rqou> !csharp new Action(() => { return 42; })()
<Qboid> (1,21): error CS8030: Anonymous function or lambda expression converted to a void returning delegate cannot return a value
<egg|zzz|egg> !csharp Func<int> rqous_own_method=() => { return 42; };
<egg|zzz|egg> !csharp rqous_own_method()
<Qboid> 42
<egg|zzz|egg> rqou: ^
<rqou> wait, it's stateful?
<Ellied> ooh, are those persistent?
<Ellied> !csharp rqous_own_method
<Qboid> System.Func`1[System.Int32]
<Ellied> !csharp rqous_own_method()
<Qboid> 42
<egg|zzz|egg> not that persistent, I think when the bot dies it goes unless you ask very politely
<egg|zzz|egg> and there's a command to clear the state
<rqou> but how good is the sandboxing?
<Ellied> yeah, I was gonna ask that. how much trust is involved here? :P
<egg|zzz|egg> rqou: please don't do silly things to Thomas's machine
<egg|zzz|egg> !wpn
* Qboid gives egg|zzz|egg an expansion
* egg|zzz|egg waves an expansion around
<rqou> lol
<rqou> anyways, back to the original question of "halp, i can't math"
<rqou> what if we somehow handwaved enough that you do have a Lie group?
<egg|zzz|egg> rqou: well we got to the point where we formalized a couple of lines of your slides and then bofh and I got to "halp I can't tangent bundle" too :D
<rqou> oh dang i just realized it's super late over in Zurich
<rqou> maybe you can explain it more some other time?
<rqou> thanks for the help so far at least
<rqou> i definitely need to buy you something somehow at some point :P
<egg|zzz|egg> catpics
<rqou> unfortunately i'm not surrounded by cats right now
<rqou> a friend used to have a cat, but that cat finally passed away a while back
<rqou> egg|zzz|egg: ok, here's one low-quality catpic: https://photos.app.goo.gl/wITFZTX0wffIG4wy1
<egg|zzz|egg> cat!
<rqou> RIP cat
<rqou> anyways, egg|zzz|egg you should go zzz for now since homework isn't imminently due :P
<egg|zzz|egg> 貓
<bofh> 學名：Felis silvestris catus
<egg|zzz|egg> ᠮᠦᠦᠷ
<egg|zzz|egg> (please turn your screen to view the preceding line)
<rqou> wtf
<rqou> Mongolian or Manchu?
<egg|zzz|egg> mongolian
hattivat has quit [Quit: WeeChat 1.9]
<bofh> ugh, I need to install a Mongolian font.
<bofh> https://en.wikipedia.org/wiki/Rijndael_MixColumns WHY IS THIS A WIKIPEDIA ARTICLE.
<egg|zzz|egg> there are weird articles
<bofh> like it comes with test vectors and a matrix for how to multiply by 3,9,11,13 & 14 in GF(2^8), even
* egg|zzz|egg continues finding the notation GF oddd
<SnoopJeDi> holy moly, 1500 observable periods?!
icefire has quit [Read error: Connection reset by peer]
<SnoopJeDi> apropos of nothing, Michener's "Space" gives a shout-out to Penzias and Wilson! Two of the characters get into an argument about the coming death of the Apollo program and it comes up as an example of on-going fundamental science.
<UmbralRaptor> ?
<SnoopJeDi> CMBR \o/
<SnoopJeDi> UmbralRaptor, "Space" is historical fiction about space research/rocketry from the end of WWII until roughly the shuttle program (it was published in the 80s)
<SnoopJeDi> it, uh...well, right now, it's inventing an Apollo 18 to visit the far side to give the fictional main characters some stuff to do.
<SnoopJeDi> but overall it treats the history pretty fairly, Michener's known for good historical fiction
<bofh> not bad, certainly sounds cool.
<SnoopJeDi> I wish it was annotated like "Texas" was, I'm not sure if that was a one-off for him or if "Space" is the outlier with the history being so recent
<SnoopJeDi> but wikipedia fills the gap nicely
<SnoopJeDi> Actually, I have a copy of "Chesapeake" waiting to be read on my bookshelf...guess I could check if that has endnotes.
<SnoopJeDi> Ack, it does not :(
<bofh> damn
<SnoopJeDi> That one should be fun though, hometown history :D
<Ellied> ah, the joys of linux text editors.
<Ellied> Me: "are you sure you want to use IDLE? it kinda sucks compared to a proper editor." Students: "Well, what do you use?" Me: "er, vim, but you don't have t-" Them: *eyeroll*
<SnoopJeDi> hey, gvim works just fine on Windows!
<SnoopJeDi> IDLE is...well, I don't know of a single person who recommends it aside from Guido
<Ellied> now they've found some weird IDE for python that apparently won't let you run a script if it doesn't pass some nebulous non-standard criterion and treats GPIO channel-in-use warnings as fatal errors
<SnoopJeDi> it's like if you wanted to use IPython, Jupyter, or Spyder, except have it be bad
<Ellied> they're all on RPis, so linux abounds
<SnoopJeDi> I'm just being a git
<SnoopJeDi> but yea, IDLE is pretty objectively bad :(
<Ellied> most of them also have macs, only two use windows and neither tends to bring their laptop to class
<Ellied> they agreed with me about IDLE at least
<Ellied> most of them just use nano now. I suspect they will succumb to the cult of vim eventually.
<Ellied> I thought Vim was great once I got past the first ~2 hours or so
<Ellied> there's like four stages of vim: 1. "how the hell do I exit this *&^(*@&^* program?!" 2. "ok fine maybe it's good but I don't have time to learn it." 3. "huh, this isn't too bad, but it occasionally does weird things and I have to mash keys till it stops." 4. "Vim is the only REAL text editor."
<SnoopJeDi> vim-adventures.com is a nice propaganda tool
<SnoopJeDi> LOL I hadn't heard before that LIGO Livingston had been shot
<SnoopJeDi> ...there should be a Wikipedia article "List of scientific instruments damaged by gunfire"
<bofh> ROFL, WHAT? DETAILS.
<SnoopJeDi> Haven't tracked it down to anything, but catching up on the LIGO presser and during the YouTube Q&A they said the detector in Lousiana has been (unintentionally) shot at by hunters before
<SnoopJeDi> oh, huh. It was anticipated in '89
<SnoopJeDi> https://dcc.ligo.org/public/0038/G990012/000/G990012-00.pdf slide 35 has a picture of a bullethole
<soundnfury> Ellied: you know I have to mention ed now
<FluffyFoxeh> Ellied: I'm a vim user. But recently I've been trying emacs
<FluffyFoxeh> emacs seems to be a different class of program altogether, really
<FluffyFoxeh> I mean, it ships with an IRC client, a newsreader, an email client, and a bunch of games (snake, pong, etc). I think there's a text editor in there somewhere
<FluffyFoxeh> Swiss army knife of text editors
<FluffyFoxeh> oh and a web browser lol
xShadowx has quit [Ping timeout: 383 seconds]
xShadowx has joined #kspacademia
<egg|zzz|egg> !wpn whitequark
* Qboid gives whitequark a depressurized descriptive goose
<egg|zzz|egg> that reminds me of that conversation with Ellied and Iskierka about depressurizing a fish
<egg|zzz|egg> !wpn Fiora
* Qboid gives Fiora an ideal Ꙭ
<egg|zzz|egg> !wpn bofh
* Qboid gives bofh a decomposition
<whitequark> !wpn Fiora
* Qboid gives Fiora an involutory cube/µa741 hybrid
<soundnfury> !wpn egg|zzz|egg
* Qboid gives egg|zzz|egg a backward variety
<egg|zzz|egg> whitequark: have you found an additional kitten?
egg|phone|egg has joined #kspacademia
egg|cell|egg has quit [Ping timeout: 183 seconds]
egg|phone|egg has quit [Read error: Connection reset by peer]
egg|phone|egg has joined #kspacademia
egg|phone|egg has quit [Read error: Connection reset by peer]
<whitequark> egg|zzz|egg: nope
<egg|work|egg> aw
<egg|work|egg> whitequark: is kotya doing ok? (sorry I haven't set up a cyrillic layout on my work keyboard yet)
<egg|work|egg> !u U+A999
<Qboid> U+A999 JAVANESE LETTER JA MAHAPRANA (ꦙ)
<egg|work|egg> !wpn Iskierka
* Qboid gives Iskierka a Hermitian hydra
TonyC1 has quit [Ping timeout: 183 seconds]
<kmath> <kevinschawinski> I just realized that I haven’t used the letter “ß” in… years? A decade?
<egg|work|egg> !u U+13379
<Qboid> U+13379 EGYPTIAN HIEROGLYPH V011A (?)
<egg|work|egg> UmbralRaptor: yeah, in switzerland it's not used
<egg|work|egg> (otoh if I don't use it here e_14159 will probably and rightfully yell at me)
<Iskierka> Switßerland
* Iskierka runs
<egg|work|egg> !wpn Iskierka
* Qboid gives Iskierka a Jovian soap/ruby hybrid
<UmbralRaptor> !wpn Iskierka
* Qboid gives Iskierka a venomous axe
<kmath> <evolscientist> "Do you have any special items that need extra care?" "I have a woolly mammoth fossil." "A what??" First time the movers ever got that one.
* Iskierka uses the axe on the ruby
<Thomas> In germany we recently even got a capital ß. Because...reasons
APlayer has joined #kspacademia
<UmbralRaptor> !wpn APlayer
* Qboid gives APlayer a californium purpose
<APlayer> !wpn UmbralRaptor
* Qboid gives UmbralRaptor a baize aluminium tarrasque-like piston
APlayer has quit [Ping timeout: 383 seconds]
APlayer has joined #kspacademia
<e_14159> egg|work|egg: I will not yell at you.
<e_14159> I might write a strongly-worded chat message.
<egg|work|egg> !wpn e_14159
* Qboid gives e_14159 a modular coilgun
* e_14159 swaps out a module.
* egg|work|egg gives e_14159 an ſz
* egg|work|egg gives e_14159 a ꜩ
* e_14159 hands egg fossilized language features.
<SnoopJeDi> heh, I guess Steven Weinberg feels left out with the LIGO fuss yesterday, he's been giving a colloquium for the last hour or so which is kinda rambly
* UmbralRaptor ? things
<APlayer> Ellied: Another problem. After one cycle of the circuit, the capacitor "saturates" on the MOSFET Gate connected side, and does not permit the setup to power up. Will it "recharge" from the ground and the low UART pin within a reasonable time?
<APlayer> That is, no, it saturates from the battery terminal connected side
<APlayer> It needs a way to drain, I guess?
<APlayer> Please ;tell me if you have any idea, I'll be back soon.
APlayer has quit [Ping timeout: 204 seconds]
APlayer has joined #kspacademia
<APlayer> Back!
<whitequark> egg|work|egg: not that well
<whitequark> really stressed out
scribbles has joined #kspacademia
<UmbralRaptor> So today was more exciting than I wanted, but my car is back and (mostly) legal.
<UmbralRaptor> whitequark: it's weirdly ambiguous as to if you or the kitten are stressed out. (both?)
scribbles has left #kspacademia [Leaving]
<Ellied> s
<bofh> SnoopJeDi: wait, you're at a Weinberg colloquium?
<Ellied> APlayer: It should. If there's any trouble with that, add a large resistor (e.g. 100k) from the battery + to the battery -.
<APlayer> And what causes it to lose charge?
<APlayer> loose*
<APlayer> (Or which is correct?)
<Ellied> when the battery stops supplying power, it can discharge through that resistor.
<APlayer> I mean without resistor
<Ellied> without a resistor it should slowly lose charge through the 100k resistor and switched-off n-channel FET, but that will be slow
<APlayer> Ah.
<APlayer> According to falstad, the charge changed by 0.17 V within 20 sec
<APlayer> IIRC, at least
<APlayer> Would it be a better option to wire in a button and open the case/press the button whenever I need to start up the Pi soon after switching it off?
<APlayer> A button instead of a resistor, that is
<Ellied> unless you need to start it up right after you turn it off very often (specifically, without using reboot, actually fully shutting it down and then turning it back on)
<APlayer> I don't see that happening, no
<Ellied> if you really want to get rid of that behavior, add a diode with its anode in ground and its cathode on the gate of the N-channel, to make the capacitor go back to neutral almost immediately.
<Ellied> that might be a good idea anyway if you're using a polarized capacitor, which you likely are at 20 µF
<Iskierka> trying to verilog over ssh -x: slow
<Iskierka> but at least it's mostly written and I'm just poking at things
<Ellied> assuming you mean -X, try -XC?
<Ellied> that'll enable compression and likely make things a little faster
<APlayer> After you suggested that I lower the MOSFETs voltage, I reduced the capacitance to 5 uF and eventually found a 4.7 uF one at home
<Iskierka> google states that -C disables compression
<APlayer> Seems to work well in the sim
<Ellied> say what
<Ellied> Iskierka: my man page for ssh on debian says the following:
<Ellied> -C - Requests compression of all data (including stdin, stdout, stderr, and data for forwarded X11, TCP and UNIX-domain connections). The compression algorithm is the same used by gzip(1). Compression is desirable on modem lines and other slow connections, but will only slow down things on fast networks. The default value can be set on a host-by-host basis in the configuration files; see the
<Ellied> Compression option.
<APlayer> Ellied: Funny thing, I thought of using a diode but I couldn't figure out in my head how that would work and be useful. To be honest, I am not even sure now that you've told me
<Iskierka> I've restarted with it as it seemed to have given up doing things anyway, but I think it's more just the amount of back-and-forth over a small but significant latency
<APlayer> You mean it would be pointing from the battery in the direction of the capacitor?
<Ellied> APlayer: it allows current to flow from ground to the gate if it goes negative (e.g. if a resistor is pulling down the other side of the capacitor)
<Ellied> here, I'll link you the falstad thing
<APlayer> Well, no, that's not quite happening
<APlayer> It's that the upper half of the capacitor remains charged at just below 5 V
<Ellied> you need that resistor
<APlayer> The 100K resistor left of the battery?
<Ellied> yes
<Ellied> that will discharge the capacitor to ground after power is removed
<APlayer> Yeah... Still seems weird to "short" the battery just like that
<APlayer> Would it draw a lot of energy?
<Ellied> No.
<APlayer> Humm, okay
<APlayer> Is there a way to measure that in falstad?
<Ellied> 5V/100000Ω = 50µA, no?
<APlayer> I mean over the whole circuit
<Iskierka> unfun: the 9 windows it decides to open if you misclicked elaborating the test module
<Ellied> yeah, if you roll over the power +5V node it tells you the total current
<APlayer> Ellied: Yes, but that's another 50 uA drawn during RPi operation
<Ellied> the Pi draws like 500 mA
<Ellied> that's peanuts by comparison
<APlayer> I don't think it was 500 mA
<APlayer> IIRC it was around 50 mA including the display
<APlayer> Anyway my battery is 5200 mAh rated but I suspect it's way below that by now, it is old
<APlayer> Well, no
<APlayer> No way it draws 50 mA
<Iskierka> depending on use patterns batteries that old may still have very good capacity. Time alone is a poor predictor of lithium performance
<APlayer> Must be more
<Ellied> I don't believe your Pi and screen only draw 50 mA between them. The lowest I've heard is someone getting an original Pi Zero down to 30 mA by disabling all the peripherals and running idle
<APlayer> Iskierka: There is also that it seems to discharge pretty quickly even when not used. Nearly empty in less than a week.
<APlayer> Ellied: Yes, seems too little indeed
<Iskierka> you have one with a control package, yes? Might be that something stays connected and does use power
<APlayer> I just had this number in my head from back when I was choosing a suitable battery
<Ellied> a Pi 3 doing anything with wifi enabled will draw at *least* 200 mA, likely much more
<APlayer> Iskierka: Maybe... That would suck, I am designing this thing with a custom-tailored battery holder and it was envisioned as a portable device
<Ellied> my uni's wifi just went to shit again, I'll be in and out
<APlayer> If a new battery of the same model does the same, I don't know too
<SnoopJeDi> bofh, naw he broadcast it on YouTube. Shoulda linked it. Nothing really worth reporting I think https://www.youtube.com/watch?v=mX2R8-nJhLQ
<kmath> YouTube - "Reminiscences of the Standard Model" - Special Colloquium by Steven Weinberg
<APlayer> Ellied: IIRC I rated it so that it would last for 4 hours on a 3200 mAh battery. Probably will last the same on this one
<Iskierka> ... okay, I suppose I shouldn't be surprised the strange way I did subtraction is setting the wrong flags, but is it getting the right number ...
<SnoopJeDi> I started watching at the end though, so I may have missed the "good stuff"
<APlayer> Since I still suspect it underperforms
<SnoopJeDi> the audio quality is atrocious though :(
<Iskierka> answer: yes. Further question: what does it take to fix these flaaaaaags
<Ellied> you would *think* I would get few latency problems talking to a computer that's *upstairs* but apparently anything can be a federal fucking issue in DePaul University IT
<bofh> SnoopJeDi: so I think my time'd be better spent rereading Weinberg vol. 1 :P
<Iskierka> ... remarkably the overflow flag is working o.O
<SnoopJeDi> Probably :)
<Ellied> latency from there to the IRC server is a complete non-issue, it's entirely internal
<SnoopJeDi> I think maybe he got jealous of LIGO/Virgo bofh
<APlayer> Also, a question on W-LAN connections...
<APlayer> A while ago I was staying at a room for vacations. They had a portable WiFi device and told us we had to charge it overnight and we could take it out to the garden during the day, and it povided W-LAN
<APlayer> And then it hit me: How can that work?
<Ellied> That uses a cellular data connection
<Ellied> just like a smartphone using wi-fi tethering
<APlayer> Might be...
<Ellied> I mean, those are very common here and I don't know of any other kind of portable hotspot like that
<Iskierka> literally is
<Ellied> it's just a cell-to-wifi bridge
<APlayer> Okay then? I've never seen such a thing before
<Ellied> see if it has a sim slot somewhere on it
<SnoopJeDi> they've been around for a while, but didn't start taking off until c.a. 2010
<Iskierka> some higher-performance ones can use multiple networks at once and are used for real-time streaming by just throwing ALL the data and hoping one of them will manage to work
<APlayer> At first it sounded to me like "charge up some internet overnight and use it during the day"
<Ellied> lol, not sure how that would work
<APlayer> That's the point. I am not either. :P
<Iskierka> a smart thing to offer though, as they can give you the password only to the one for your room and monitor each visitor individually with ease
<Ellied> barring causality violations, all real-time internet connections need to involve a data link that operates during said particular time
<Iskierka> (or just leave it fully responsibility of the mobile operator)
<SnoopJeDi> cache all the things?
<Iskierka> Ellied: RFC 2549
<SnoopJeDi> counts as a link :P
<Iskierka> what amuses me is the thought that it RFC 2549 may actually form the basis for the internet on a mars colony
<Ellied> I mean to say that this conversation is not fully cached, in order to answer you, I have to first see your message, meaning it has to be sent first. :P
<SnoopJeDi> worked great for that one white-water rafting company
<SnoopJeDi> attach SD card with photos, send downriver and print out photos for disembarking passengers
<Ellied> downriver just floating in the river?
<SnoopJeDi> ahead of the rafts IIRC
<SnoopJeDi> I don't remember the specifics and it was a kind of weird niche curiosity anyway
<SnoopJeDi> the point being that high-latency-high-throughput is a useful thing, as it has always been
<Iskierka> woo the weird way to subtract worked
<Iskierka> not sure if it's technically faster than the two's complement though
<SnoopJeDi> Iskierka, "woo the weird way to subtract worked: the story of QCD"
<Iskierka> QCD?
<Qboid> Iskierka: [QCD] => Quantum ChromoDynamics
* UmbralRaptor renormalizes SnoopJeDi.
<APlayer> Ellied: This conversation is happening as random messages are restored from cache in real-time
<UmbralRaptor> Ellied: something something acausal com- *is eaten by a basilisk*
<Iskierka> I can see intuitively why ~(~A+B) == (A+ 2c(B)) == (A-B), but I'm slightly unnerved by how easy the flags are
<Iskierka> I feel like I should be screwing up the overflow or something with an off-by-one condition
<Iskierka> but instead the full test stimulus doesn't find a case where the flags mismatch, so ...
<Ellied> My prof is using Sonic Pi for class and it's a little strange
<bofh> Sonic Pi?
<Ellied> the idea of it is that you write code and it makes music
<UmbralRaptor> Is it fast? Does it use a (token) ring network?
<Ellied> the strange thing is that he's trying to use it to generate various combinations of tones, except when you tell it to sustain a note produced using any voice, it ignores all but one frequency and sustains that one while the rest damp out just the same
<Ellied> do you get what sounds like a damped guitar chord or whatever followed by annoying sine ringing
<SnoopJeDi> oh my gosh, not only is there a 600 page book about LBNL's history, my library has electronic access ?
<Ellied> so no matter what instrument voice you choose, the sustained sound is *always* a sine
<APlayer> Ellied: That one resistor doubles the current consumed by the circuit, actually
<Ellied> puts a bit of a damper, no pun intended, on having students view the different waveforms of different instruments on the "oscilloscopes" (actually logger pro, grumble grumble) unless they sample during the first half-second the note plays.
<Ellied> APlayer: that's because you didn't make the Pi in your simulation draw realistic amounts of current
<APlayer> Well, yes
<APlayer> But I mean the circuit only, not the RPi
<SnoopJeDi> crappy digital o-scopes are a wonderful thing for labs
<APlayer> Also, when I do this and shut off the battery, it errors out with "Convergence failed"
<APlayer> Huh
<Ellied> dunno about the convergence thing, but I'm pretty sure the circuit drawing a few tens of microamps isn't going to matter compared to the Pi
<Ellied> even if the Pi and screen really do draw only 50 mA together, that resistor draws *1000 times* less.
<APlayer> Very well, convinced me
<APlayer> Could you have a final look at this? http://tinyurl.com/y7ctutaq
<APlayer> Ah, wait, that's the one with the error. Just reset it
<Ellied> looks good to me
<APlayer> Okay then. I did not use the diode, because, really, do I care about that?
<SnoopJeDi> ooooh, neat. "Many of the Laboratory's earliest workers, including Lawrence, had been radio hams in their youth; they continued the sport on a grand scale by a ham link between the Laboratory and one of its earliest satellites at the University of Michigan."
<APlayer> It'll have some negative charge there, but it quickly disappears
<Ellied> yeah, probably not necessary
<APlayer> Okay, thanks!
<SnoopJeDi> "It is said that Lawrence used to tune his home radio to the cyclotron's operating frequency to monitor its, and his students', performance."
<SnoopJeDi> HAH
<bofh> ROFL
<APlayer> Just one more thing. I should write a list of the MOSFET specs I will need so I can ask at my school and my father can ask at his work. What kind of specs do I care about? Is there some sort of maximum rated current/voltage? Aside from the threshold voltage.
<bofh> SnoopJeDi: hey that *would* work.
<bofh> 19:09 <@SnoopJeDi> crappy digital o-scopes are a wonderful thing for labs
<APlayer> SnoopJeDi: I don't think I got that
<SnoopJeDi> evidently! the fore material of this chapter is talking about how it interfered with commercial/police broadcasting
<bofh> more than just for labs, thank heavens for cheapo Rigol DS1052Es
<SnoopJeDi> fair nuff :)
<bofh> (I've come a long way since my first oscilloscope, which was literally a CRT TV I found at the side of the road and a guitar amp a friend gave to me)
<SnoopJeDi> APlayer, which part? Cyclotrons (and modern accelerators) are inherently radio-frequency devices
<Ellied> >can't open libmozsqlite3.so: no such file or directory. >libmozsqlite3.so is literally right there, in that directory
<SnoopJeDi> bofh, what's the scientific equivalent of "that's metal" because that's metal
<Iskierka> "cheapo" £245 ex VAT
<Ellied> that's cheap for a digital scope
<bofh> ^
<APlayer> SnoopJeDi: How does that help monitor anyone's performance?
<bofh> (horizontal deflection coils go to +HV, input to vertical deflection coils goes to guitar amp which is run in the "okay, it's mostly linear here" regime)
<SnoopJeDi> oh it probably doesn't very much and is probably just an idiosyncratic expression of scientists being weirdos who can't properly separate work and leisure
<Ellied> the "cheap" scopes we have at my uni are over a kilobuck. The "good one" is probably at least ten times that.
<Iskierka> he can hear them break it
<SnoopJeDi> but I guess if something went wrong he'd hear a pop
<SnoopJeDi> (and then silence)
<APlayer> Okay
<bofh> Yep, similarly here. Agilent shit ain't cheap.
<bofh> granted, a lot of that is due to hilarious fucking markup.
<Ellied> people on freenode keep asking me if my uni's physics department is "underfunded" because we still use RS232 for things, and I'm like, dude, just the equipment they let me sit on in my own lab is probably worth the price of a decent used car
<SnoopJeDi> they must make them out of calculators
<soundnfury> bofh: is that amusingly overpriced intercourse, or overpricing of amusing intercourse?
<bofh> once replaced a start capacitor on a rotary vane vacuum pump with an identical one that cost $10 on Newark/Element14, would've cost $195 from the company (or wait who knows how long for the university to handle it, at which point that lab would be at 1 working rotary vane pump out of 3).
<APlayer> Ellied: But the WiFi is probably worth the price of one that was sat upon by a decent used car :P
<Ellied> sounds about right
<SnoopJeDi> Ellied, the microscopy and counting equipment we used in my ugrad modern physics lab used zip drives as the primary means of transferring our data, heh
<SnoopJeDi> because neither networks nor USB are real and Win2000 is the only OS
<bofh> hey, at least that Win2000 isn't internet-facing... I hope?
<Ellied> the physics department has the funding to get nice things; IT is a completely separate department made of prowling goblins that do things at random and try to kill you if you talk to them
<SnoopJeDi> s'fair bofh and hey if the SEM ain't broken don't fix it
<APlayer> Yesterday at school we found a 0.2 * 0.2 * 0.4 m box. Turns out it was a 5 MB hard drive
<bofh> yep, good lord.
<bofh> SEMs are ungodly expensive and finicky as fuck.
<APlayer> Well, no, probably larger
<SnoopJeDi> it's insane how recent they are, too
<SnoopJeDi> but they're already a ho-hum tool
* SnoopJeDi is, relatedly, deeply concerned how few colleagues know the story of STM->AFM
<bofh> Admittedly, AFM is new enough that many people are unfamiliar with it.
<bofh> (Also is unspeakably trippy as fuck)
<Ellied> My response to those freenode people is "some equipment is so expensive that you don't upgrade it just because a slightly shinier interface bus came out"
<Ellied> Although while I say that, a *very suspicious* quantity of our equipment has GPIB, so I suspect they may have done exactly that back in the 1980s or whatever
<bofh> nah, GPIB is just insanely ubiquitous.
<SnoopJeDi> bofh, I love that IBM revisited making STM stop-motion movies, it warmed my heart
<Ellied> is it really? I thought it was a fairly narrow window while it was the thing
<bofh> thankfully, GPIB<->USB adapters exist nowadays so I no longer routinely check the e-waste for ISA GPIB controllers.
<Iskierka> an uprgade for a controlling PC of an SEM seems more justifiable. presumably doesn't need what would be called a giant today
<SnoopJeDi> Iskierka, software is hard.
<bofh> Iskierka: that could mean totally rewriting the controlling s/w.
<SnoopJeDi> Like, orders of magnitude harder than hardware
<Ellied> I would check e-waste for anything GPIB just to salvage the connector for stuff
* SnoopJeDi glances at the rise of VMs
<bofh> and s/w is hard, *especially* if your business is SEMs, not C# or whatever.
<Iskierka> and the manufacturer doesn't have a version for anything other than 2000?
<APlayer> "Is your ware hard enough? Nokia disagrees"
<Ellied> what's that connector called, anyway? Is it bespoke to GPIB, or used for other things too?
<SnoopJeDi> Iskierka, see above: if it ain't broke, don't fix it
<Iskierka> 2000 tho
<SnoopJeDi> low gain, high risk
<Iskierka> it is broke
<SnoopJeDi> now that said, it *should* probably at least be connected to the intranet so you can get the gorram files off the thing :|
<SnoopJeDi> idk duct-tape some crazy FTP shit together or something just let me get my images without a zip disk I happened to save from my teenage years
<Ellied> our spectrometer doesn't have software for later than 2000, although it apparently runs on XP. my prof's approach was just to develop a new driver for the RPi.
<Iskierka> connect it via a pi that will only allow transmission of appropriate files to avoid exposing the 2000-ness
<Ellied> that is, have me do that. I wrote a few hundred lines of python that *mostly* do the trick, although calibration is still uncertain.
<SnoopJeDi> yea the SEM was probably the more up-to-date computer
<SnoopJeDi> The ones we used for positron/electron counting were...older.
<APlayer> Anyway, Ellied, so I mainly care about the threshold voltage, the continuous drain current and the gate-source voltage?
<bofh> Ellied: I think they're only used for RS-488, like Amphenol specifically designed them for that.
<Ellied> is it really called RS-488? I've only seen it written IEEE 488.
<Ellied> or in the case of the ornery control box we have for it, "IEEEE 488"
<SnoopJeDi> hehe
<bofh> rofl
<Ellied> APlayer: for the N-channel, you basically only care about threshold, since it will not see any major current. The P-channel needs to be beefy since it handles the actual current, and needs a threshold less than about 4 volts or so.
* APlayer helplessly watches a new browser window slowly but surely fill up with tabs
<bofh> Ellied: you're right, I conflated a few things. I meant IEEE-488.
<Ellied> or rather, greater than -4 volts, as it will likely be written.
<bofh> (sorry, IEEEE-488 :P)
<APlayer> Ellied: Makes sense, thanks. Also, I am not sure, are the terms used on mouser.com what I think they are?
<Ellied> APlayer: they likely are
<APlayer> I.e. did I just name the terms for the maximum rated current and voltage?
<APlayer> Yeah, -4 volts
<APlayer> I just estimated -3, but I guess anything in the range -1 to -4 is fine
<Ellied> yeah, continuous drain current is the max current it can handle while on, gate-source voltage max is probably *not* something you care about unless it happens to be less than ±5V, threshold gate-source voltage is the one you want to get as small as you can find
<APlayer> What does the threshold gate-source do?
<APlayer> Is it just the threshold that falstad prompts me to enter too?
<Ellied> threshold gate-source (Vgs_thr) is where it turns on. max gate-source (Vgs_max) is where it breaks.
<Ellied> the ones in falstad have no max as far as I know because it doesn't model component failure.
<APlayer> Ah, makes sense
<Ellied> exceeding the gate-source voltage max is the easiest way to break them, because you can do it just with the little bit of static charge on your body if you touch the gate with the source attached to something else. That voltage between you and it might be hundreds or thousands of volts, but you might not even feel a thing because it equalizes so fast.
<Ellied> problem is it might equalize by blowing a hole in the oxide layer inside the FET, which will kill it.
<APlayer> Okay, so I am looking for an N-channel one with Vgs_thr of 0.5 - 1 V, Id of at least 1 mA and a P-channel one with Vgs_thr of -1 - -4 V, Id of at least 1 A. Both with Vds_max of around 10 V or more
<Ellied> sounds good
<Ellied> Vgs_thr of 2V on the N-channel should work. I doubt you'll find one very far below 1V.
<APlayer> I am not sure 2V gives me the delay I need... let me look
<APlayer> Nope, not enough
<APlayer> But 1.2 V was just barely
<SnoopJeDi> LOL I have Weinberg on in the backround and he just said "technicolor theories" in reference to exotic no-Higgs scenarios
<Ellied> try increasing the capacitance or resistance or both
<APlayer> Resistance seems the easier way
<Ellied> yeah 10M is a common resistance
<Iskierka> isn't higgs now confirmed?
<APlayer> Ellied: Charges more slowly now, though
<bofh> Iskierka: it is, beyond any doubt, so I have no clue what Weinberg was talking about.
<APlayer> 10 sec now and not charged fully yet...
<SnoopJeDi> oh he's giving an oral history so he was talking about pre-discovery
<SnoopJeDi> and CMS/ATLAS were *very* careful to say "we found *a* Higgs" rather than "we found *the* Higgs"
<SnoopJeDi> because truth is we don't know very much at all about it as yet
<Ellied> charges more slowly? what do you mean
<APlayer> The capacitor charges slowly if the discharge resistor is increased
<APlayer> I used 2 M and it seems good with a 2 V threshold on the MOSFET
<APlayer> 10 M was just too slow
<APlayer> And I am mildly concerned about falstad going mad when I shut down the "battery"
APlayer has quit [Ping timeout: 383 seconds]
hattivat has joined #kspacademia
APlayer has joined #kspacademia
<egg|zzz|egg> !wpn hattivat
* Qboid gives hattivat a magnetohydrodynamic Лидов ship
<egg|zzz|egg> hattivat: well I ended up writing cat in hieroglyphs on my whiteboard while discussing something with a colleague today
* egg|zzz|egg is good at nerd sniping
* egg|zzz|egg is not very good at birbs though, my quail chick looks like a pigeon with a huge head
APlayer has quit [Ping timeout: 204 seconds]
<Iskierka> cat requires birb?
<kmath> https://twitter.com/hamesatron/status/920130873873145856 <hamesatron> hi im a 32 year old audio director and this is how i name my tracks even though nobody ever sees them https://t.co/PEE0iiwDTD
<SnoopJeDi> "PIA-YES???" gave me a good exhale
<hattivat> egg|zzz|egg: awesome!
<hattivat> !wpn egg|zzz|egg
* Qboid gives egg|zzz|egg a death IDE
<UmbralRaptor> Integrated Death Environment
<egg|zzz|egg> Iskierka: yes, cat requires birb
<egg|zzz|egg> Iskierka: ????
<egg|zzz|egg> Iskierka: milk jug - reed - quail chick - cat
<egg|zzz|egg> (cat also requires cat, as a determinative)
<Iskierka> ... egyptians are weird
<UmbralRaptor> egg|zzz|egg: resolving circular dependencies wasn't accomplished until the Ptolemaic period?
<egg|zzz|egg> hattivat: can cat also be used logographically?
<egg|zzz|egg> hattivat: do you need to stand the cat on a pole to do that?
<UmbralRaptor> Uh
<rqou> why do i have the font for this?
* UmbralRaptor hopes that pun was intended?
<rqou> !u ????
<Qboid> U+133C7 EGYPTIAN HIEROGLYPH W019 (?)
<Qboid> U+131CB EGYPTIAN HIEROGLYPH M017 (?)
<Qboid> U+13171 EGYPTIAN HIEROGLYPH G043 (?)
<Qboid> U+130E0 EGYPTIAN HIEROGLYPH E013 (?)
<egg|zzz|egg> UmbralRaptor: yes though you literally stand logograms on a stick https://en.wikipedia.org/wiki/Egyptian_hieroglyphs#Logograms
<UmbralRaptor> rqou: Did you install Oreo?
<rqou> no, this is my laptop
<Iskierka> rqou, everyone does these days
<Iskierka> thanks emoji
<rqou> also, no oreo for me using a huawei phone :P
<kmath> https://twitter.com/bofh453/status/920399491450236928 <bofh453> <@eggleroy> (cat also requires cat, as determinative) <@Newpa_Hasai> resolving circular deps wasn't accomplished until the Ptolemaic period?
<hattivat> egg|zzz|egg: I guess, though honestly no idea
<hattivat> also, aren't hierglyphs mostly phonetic?
<bofh> SnoopJeDi: I lost it at "im not sure what this is" "oh its more drums phew"
<UmbralRaptor> rqou: All hail the Nexus 5X!
<bofh> also "straight up?? a tuba"
<rqou> i had a 6p that died due to battery issues
* UmbralRaptor ignores the severe hardware flaw.
<egg|zzz|egg> hattivat: yeah but *really specific* determinatives
<egg|zzz|egg> hattivat: also some logograms
<hattivat> yeah, I know, but would they need one for cats?
<hattivat> I guess they might have one for Bastet, assuming she counts as a cat
<egg|zzz|egg> hattivat: they have a determinative for cat
<egg|zzz|egg> it's a picture of a cat
<Iskierka> egg|zzz|egg, what is ???? phonetically?
<egg|zzz|egg> mi i w [determinative for cat]
<hattivat> miiw? <3
<Iskierka> ... you're saying they literally called cats meows?
icefire has joined #kspacademia
<hattivat> another brutal example, divine cat-rabbit slashing a snake with a leaf http://1.bp.blogspot.com/-clyZ0dH6zB0/UcgDd9_U8SI/AAAAAAAAogo/k4brP79Oto4/s1600/apofis_el_gran_enemigo_de_re_807x762.jpg
<Iskierka> unrelated link says yes, cats are meows
<egg|zzz|egg> hattivat: the ram hymn Ꙩ_ꙩ https://www.flickr.com/photos/ckirie/34268340834
<hattivat> egg|zzz|egg: that link doesn't show me anything about ram
<kmath> https://twitter.com/Newpa_Hasai/status/920322446837854208 <Newpa_Hasai> Additional achievement unlocked: Car sufficiently beat up that your apartment complex assumes you have abandoned it. https://t.co/3KrdNUy3QS
<egg|zzz|egg> (auf deutsch)
<egg|zzz|egg> hattivat: wait what
<hattivat> "every single sign is a ram"
<Iskierka> scroll down to next paragraph
<hattivat> I'm not seeing it
<hattivat> ...it doesn't show me any paragraphs
<hattivat> maybe it's geoblocked or sth ? O_o
<UmbralRaptor> bofh: Actual situation was a bit more complicated, and involved registration problems also.
<Iskierka> ... it should be a link to a google book?
<hattivat> first time I'm seeing something like that on google books
<UmbralRaptor> Incidentally, the DMV at city hall seems way better than the one at the mall. >_>
<hattivat> it is, but it just shows me the cover and description
<hattivat> not the actual contents
<bofh> UmbralRaptor: there's a DMV at your local mall? :P
<UmbralRaptor> bofh: Virginia is weird.
<egg|zzz|egg> hattivat: blarg
<hattivat> egg|zzz|egg: is that sign discussed on page 8 what of http://archiv.ub.uni-heidelberg.de/propylaeumdok/3139/1/Leitz_Die_beiden_kryptographischen_Inschriften_2001.pdf what I think it is?
<hattivat> 7-8 to be exact
<hattivat> example (12) on page 7 looks particularly disturbing ;D
<egg|zzz|egg> hattivat: ah I think you're referring to two distinct hieroglyphs in fact
<egg|zzz|egg> !u ??
<Qboid> U+130B8 EGYPTIAN HIEROGLYPH D052 (?)
<Qboid> U+130BA EGYPTIAN HIEROGLYPH D053 (?)
<hattivat> well, yeah, the pre-satisfied and post-satisfied variety
<hattivat> interesting how it doesn't seem to appear in the context of crocodiles
<hattivat> only cattle
<hattivat> pastoral society, I guess
<hattivat> oh cthulhu, it really does mean that
<hattivat> D053 "penis"
<hattivat> D053 "penis with issue of fluid"
<egg|zzz|egg> hattivat: no the former is D052
<egg|zzz|egg> hattivat: used as a determinative: https://en.wikipedia.org/wiki/List_of_hieroglyphs/D
<Iskierka> egg: what were dogs called
<egg|zzz|egg> so there is a north african dog hieroglyph, and a lying dog or jackal hieroglyph
<egg|zzz|egg> Iskierka: aha here we go https://en.wiktionary.org/wiki/%E1%B9%AFzm#Egyptian
<Iskierka> ofc it doesn't give font version
<egg|zzz|egg> Iskierka: tether - door bolt - owl - north african dog
<hattivat> egg|zzz|egg: yeah, that's what I meant, brain fart
<hattivat> in any case, that cow - penis - cow - penis sequence is now even more disturbing
<hattivat> although thankfully it's not cow - penis - cow - penis with issue of fluid
<egg|zzz|egg> hattivat: aren't those rams?
<egg|zzz|egg> Iskierka: ????
<egg|zzz|egg> (except you would really need some of the proposed or newly accepted hieroglyph layout characters to make this look non-silly)
<rqou> so, how long until wordfilters start blocking U+130B8/U+130BA? :P
<hattivat> egg|zzz|egg: might be, doesn't make it any better though
<Iskierka> I assume those are coming in a future unicode and aren't available even if up to date
<egg|zzz|egg> yeah, some are in but very recent
* whitequark pokes in
<egg|zzz|egg> their absence has meant that nobody uses unicode for hieroglyphs so far
<whitequark> "cow penis cow penis"
<whitequark> what
<egg|zzz|egg> no it's actually ram penis ram penis
<whitequark> what
<rqou> troll suggestion: abuse cjk ideographic description characters to lay out hieroglyphs
<egg|zzz|egg> whitequark: hieroglyphs
<egg|zzz|egg> unicode has three penises
<egg|zzz|egg> rqou: re. word filters, dunno, people seem to be using aubergines instead for some reason, *shrug*
<rqou> lol right i forgot about that
<egg|zzz|egg> whitequark: so there's an hymn on a temple of a ram god where they wrote every word with a ram because hieroglyphs are highly redundant so you can do that
<bofh> the best part is that Segoe UI Historic has a gap in their Egyptian Hieroglyphs block.
<bofh> it is specifically the 3 penises.
<bofh> It implements *every other character* in that block.
<egg|zzz|egg> whitequark: and determinatives are used to give meaning to the text (rather than make it a herd of rams :-p)
<egg|zzz|egg> whitequark: D52 and D53 are determinatives
<hattivat> whitequark: which essentially means you use them when you want make it real clear that you are talking about the dangly bits
<rqou> egg|zzz|egg: how do you feel about "abuse cjk ideographic description characters to lay out hieroglyphs"?
<Iskierka> I saw a quote saying it was easy for an expert to read due to determinatives, but I'd argue the determinatives only help because there's too many characters to begin with. A short phonetic or near-phonetic alphabet quickly and clearly describes the word and confusion is restricted to the same as speech
<Iskierka> which then means that speech will optimise for communication and writing can follow it
<egg|zzz|egg> rqou: hm but I think the description characters are not there to perform layout, they're there to be actually rendered as-is to describe layout
<rqou> that's true, but you're forgetting the power of the ZWJ :P
<egg|zzz|egg> rqou: there are actual proposals for ideographic layout, and at least one got accepted iirc
<Iskierka> does CJK have characters to mark furigana or do systems still need to implement that themselves?
<egg|zzz|egg> s/ideogra/hierogly/
<Qboid> egg|zzz|egg meant to say: rqou: there are actual proposals for hieroglyphic layout, and at least one got accepted iirc
<rqou> yes, but i forgot what they are
<rqou> @eevee mentioned them somewhere
<rqou> ah, U+FFF9, U+FFFA, U+FFFB
<egg|zzz|egg> and http://www.unicode.org/L2/L2017/17112r-quadrat-encoding.pdf is a follow up because that might not be enough
<egg|zzz|egg> rqou: also fun, you can write hieroglyphs either RTL or LTR, but you have to flip the animals etc. around
<egg|zzz|egg> you read facing the animals as it were
<bofh> some fonts even have glyphs for this, in an OpenType 'rtla' block.
<rqou> so, when will we get hilarious things like <apple emoji>+zwj+<computer emoji> = <Macbook Pro (TM) emoji>? :P
<bofh> (I've even seen an 'rtla' block that contained RTL glyphs for the Phaistos Disc Unicode block, of all thins)
<bofh> things*
<bofh> rqou: I'm still waiting for <wastebasket emoji>+ZWJ+<fire emoji> = <trashfire emoji>
<rqou> why not <wastebasket emoji>+ZWJ+<fire emoji> = <image of donald trump>?
<bofh> b/c I don't need more reminders of that thing's existence, is why.
* egg|zzz|egg woners if we'll get coloured hieroglyphs in plain text thanks to emoji
<egg|zzz|egg> s/ner/nder/
<Qboid> egg|zzz|egg meant to say: /me wonders if we'll get coloured hieroglyphs in plain text thanks to emoji
<rqou> we already get colored astrological symbols
<rqou> but only some of them
<egg|zzz|egg> because they have emoji presentation
<egg|zzz|egg> which pisses me off because some of them are also used in astronomical texts
<rqou> i'm sure the homestuck fans love it though
<bofh> Adding 'Trump', 'Republican(s)', 'Democrat(s)' & 'congress' to my twitter muted keywords list was something I honestly should've done a year ago, but it's made things a lot more usable.
<egg|zzz|egg> (origin of right ascension)
<bofh> egg|zzz|egg: how long until coloured alchemical symbols? :P
<egg|zzz|egg> argh
<egg|zzz|egg> why don't you colour the hieroglyphs that actually should be instead :'(
<egg|zzz|egg> (although they can also be in "text presentation" of course)
<rqou> so, i'm waiting for some troll proposal for a set of 256 codepoints "U+xxxxNN EMBEDDED PNG EMOJI OCTET 0xNN"
<Iskierka> test
<Iskierka> aw
<rqou> egg|zzz|egg: very stabbity? :P
<UmbralRaptor> ping?
<rqou> UmbralRaptor: ping timeout :P
<egg|zzz|egg> "stabbity" pings the raptor
<egg|zzz|egg> hattivat: I'm really impressed at how distinguishable the birds are in cursive https://upload.wikimedia.org/wikipedia/commons/9/9d/Papyrus_Ani_curs_hiero.jpg
<rqou> egg|zzz|egg: ZWJ sequences are controlled by the font right, not some other part of the text rendering stack?
* egg|zzz|egg does not know
<egg|zzz|egg> bofh, do you?
* egg|zzz|egg doesn't know how variation selectors actually work either
<rqou> it'd be really cool to actually make @eevee's e<ZWJ>e<ZWJ>v<ZWJ>e<ZWJ>e = <map icon of an eevee>
<egg|zzz|egg> >_>
<rqou> e<ZWJ>e<ZWJ>v<ZWJ>e<ZWJ>e<VSn> = <icon of an eevee with shiny palette>
<rqou> :P
<rqou> i mean, we already have "bullshit" ligatures except the tooling to build that is a giant PITA to use
<bofh> rqou: egg|zzz|egg: well they *can be* controlled by the font, and those don't even have to be ZWJ sequences.
<egg|zzz|egg> yeah fonts can do a lot of stuff with ligatures
* egg|zzz|egg likes Qu ligatures
<rqou> why is font-related tooling awful?
<bofh> you just need a 'liga' table which forwards to a Type 3 Contextual Substitution lookup table that maps <certain char><ZWJ><certain char> to something else, in GSUB.
<egg|zzz|egg> also Th is nice in english
<bofh> rqou: I DON'T KNOW BUT IT FUCKING SUCKS
<bofh> sorry
<bofh> mild PTSD
<bofh> (I'm only half-joking :/ It's all unspeakably awful & FontForge is the worst of it by far)
<egg|zzz|egg> kinda like st and ct but some people find them noisy
<rqou> i "love" ff/fi/ffi ligatures where after you copy them out of the pdf it turns into some random PUA codepoint
<bofh> https://mobile.twitter.com/bofh453/status/745075219975507969 actual line from fontforge's code.
<kmath> https://twitter.com/bofh453/status/745075219975507969 <bofh453> Oh for fuck's sake fontforge: scaled_width = (int)rint((rint(fabs(stem->width)) * ppem * 64.0)/EM); (EM, ppem & scaled_width are all ints).
<Iskierka> just extract the font along with it!
<bofh> ahahahahahahahahahahahahahahahaha FUCK that presents its own "fun" set of complications.
<bofh> So PDF embedded fonts, if they're TrueType, will almost always lack a 'cmap' dictionary. Which means there's effectively no way to map characters to glyphs.
<bofh> If you're lucky, there's a ToUnicode CMap (which is different from an SFNT 'cmap' despite being named the fucking same), which you can parse and use to generate a 'cmap' table, and then just rewrite the font.
<bofh> This is the case... about 65% - 75% of the time, I find.
<rqou> there's also WebDings/Symbol and similar which somehow replace normal ascii characters with something else
<rqou> which somehow seems to have slowly broken over the years, but i'm not sure how
* Iskierka searches and immediately finds the proper ligatures, which render nicely in bookerly
<Iskierka> webdings/symbol are pretty straightforward ... just define the shape differently
<Iskierka> breaking is not something I've tested so don't know about though
<rqou> e.g. "Symbol" has greek where it's "supposed to have" latin
<bofh> The remainder of the cases you're literally SOL and have to artisanally hand-construct a 'cmap' yourself via visual inspection, oh and don't forget that ttx will (at least as of last git, and I should really submit my patch), fail to construct a GlyphOrder table & thus utterly fail at font decompositions if there are no 'cmap' tables in a TrueType SFNT.
<rqou> which will occasionally turn micrograms in your homework into milligrams
<rqou> yeah, now that i think about it the breaking was with "Symbol" not WebDings
<bofh> "Symbol", other than being a font (fun fact: the Greek chars in Symbol are out of extended Times New Roman. Yes, the outlines are identical. I checked) is also a name for a specific type of 'cmap' (above when I said 'cmap' I specifically meant *Unicode* 'cmap', aka a Type 4, 6 or 12 CMap with maj ID 3 & minor ID 1)
<bofh> Basically the Symbol 'cmap' (3.0 instead of 3.1) is a fixed 256-char entry map which starts at 0xF020 and ends at 0xF0FF, you're supposed to map to and back from it by ORing with 0xF000/ANDing with ~0xF000.
<Iskierka> You can solve that by just XOR, can't you?
<bofh> Needless to say if your software isn't expecting this it will get very confused, since there's actually nothing at 0x0020 - 0x00FF (or anywhere else), and if it only checks 3.1 'cmap' tables it will generally barf with 'this font has no glyphs'
<bofh> Iskierka: ...hurr. Thanks.
<Iskierka> basically symbol was mathematician's/physicist's pre-unicode solution
<Iskierka> but now those symbols actually exist so they're not here any more, go look elsewhere
<bofh> Yep.
<bofh> The only real use is legacy cases in PDF.
<rqou> well, go tell the programmers at Pearson :P
<rqou> (maybe they fixed it by now, this was a few years back)
<Iskierka> updating, the bane of working computer systems
* Iskierka wonders how long before major data is stolen by krack
<Iskierka> and, conversely, how long until the last data is stolen by this method
<rqou> Pearson Mastering<Subject> would try to encode micrograms by something similar to <font face="Symbol">m</font>g
<rqou> which firefox would render as <fuzzy m>g
<rqou> which is how after you've been burned once you can learn to recognize real milligrams from pretend milligrams
* UmbralRaptor ? Pearson with a χ².
<icefire> microsoft and ubuntu have updated for krack, some routers have. Apple vaguely mentioned that there will be an update at some point
<icefire> google has said there will be an update which probably means waiting for the next months cycle
<egg|zzz|egg> "abbreviated quail chick"
<icefire> DD-WRT has an update
<egg|zzz|egg> !wpn bofh
* Qboid gives bofh a terbium ſtabber
<icefire> my router doesn't so I should probably migrate
<egg|zzz|egg> !wpn Iskierka
* Qboid gives Iskierka a killing diffeomorphism
<egg|zzz|egg> !wpn rqou
* Qboid gives rqou a clopen porpoise
<egg|zzz|egg> !wpn Fiora
* Qboid gives Fiora a ⅝λ polygon
<egg|zzz|egg> !wpn whitequark
* Qboid gives whitequark a triaxial woomera
<kmath> https://twitter.com/bofh453/status/738794360121241600 <bofh453> *manages to segfault fontforge 12 times in 5 minutes, in 8 different code locations, while trying to do fairly simple things* WELL. THEN.
<rqou> why is "⅝λ" an adjective that Qboid has?
<rqou> is this the "wavelength" lambda or VLSI lambda?
<UmbralRaptor> I think Ellied added it?
<Iskierka> https://i.imgur.com/uhHgdGC.mp4 having not played it but going on tropes, this feels like it owuld be good for an atelier thing?
<Ellied> I don't recall adding anything with unicode fractions
<egg|zzz|egg> whitequark: hattivat: so to come back to those rams and penises, the relevant line in that german paper is "ram with a cobra on its head, penis, egg above ram, penis", which is translated to "the copulating ram", kꜣ sṯ, with the k, s, and t being denoted by the cobra, egg, and ram respectively; both penises serve as determinatives.
<whitequark> ...
<egg|zzz|egg> whitequark: the two words in the transliteration are https://en.wiktionary.org/wiki/k%EA%9C%A3 and sṯ which is mentioned here https://en.wikipedia.org/wiki/Satis_(goddess)#Names
<rqou> why does egyptian transliteration look like unpronounceable consonant soup?
<egg|zzz|egg> so I guess one of the rams has to be there to mean ram, since otherwise this doesn't appear to mean ram; but that's good because only one was used phonetically so now we're back on the expected number of rams
<hattivat> rquo: because it's a Semitic language
<rqou> ah
<hattivat> and in semitic languages vowels don't matter much
<hattivat> I mean, they are there, but you can usually skip them in writing to save on characters and still be understood
<rqou> yes, every linguistics-related course ever has to talk about k-t-b and triconsonantal roots
<hattivat> indeed
<rqou> it's then extra fun when we learn about non-semitic languages that borrowed just the word "kitab" (thanks Islam)
<hattivat> Indonesian is full of borrowings like that
<egg|zzz|egg> whitequark: if you want there's a full translation in english here https://amentetneferet.wordpress.com/gods/khnum/ (scroll down to "THE CRYPTOGRAPHIC RAM HYMN TO KHNUM-RA")
<rqou> indonesian was actually exactly what i had in mind
<egg|zzz|egg> "Maker of rams"
<hattivat> maker of rams sounds like an awful euphemism
<egg|zzz|egg> hattivat: yeah but then two lines above they said copulating ram so they're not trying to euphemize
<hattivat> true
<hattivat> copulating *rams* though
<egg|zzz|egg> nono, it's a hymn to the ram god
<egg|zzz|egg> so it's "praise to you [...] copulating ram"
<hattivat> still better than the interpretation I've had, which involved a human penis
<hattivat> oh, I see
<hattivat> so there being two rams is just coincidental, ok
<hattivat> still looks funny though
<egg|zzz|egg> well it's because they have this silly pun of writing *every word with ram*
<hattivat> neat, sort of like shi shi shi shi shi shi shi poem
<egg|zzz|egg> whitequark: hattivat: so, "he who creates rams" is written eye, bowl with smoke, ram, (some sort of sheep? can't find a sheep in gardiner's list), transliterated to ỉr bꜣw; (bowl with smoke, ram) means ram, https://en.wiktionary.org/wiki/b%EA%9C%A3#Etymology_2, and eye means make https://en.wiktionary.org/wiki/jrj#Egyptian. I have no idea what the sheep is, or is for; did they just decide to draw a sheep
<egg|zzz|egg> for padding? the german text doesn't mention its function either, if it's anything it's a determinative
<hattivat> padding with sheeps, that's interesting
<hattivat> I'm more used to geese padding, but that might be a cultural thing ;p
<hattivat> ok guys, time for me to sleep, good night everyone
* egg|zzz|egg should zzz too
<hattivat> s/guys/guys and gals
<Qboid> hattivat meant to say: ok guys and gals, time for me to sleep, good night everyone
<hattivat> gendered words suck genitalia
hattivat has quit [Quit: WeeChat 1.9]
<SnoopJeDi> so, talk today by one of our faculty who works on DES. it got super-subsumed by NS merger stuff (DES did some observing because Chile), but one thing in particular struck me about the "actual" work
<SnoopJeDi> bofh, UmbralRaptor: https://arxiv.org/abs/1512.01558
<UmbralRaptor> SnoopJeDi: ETA on HPF and NEID?
<SnoopJeDi> The abstract buries the lede badly, but tl;dr Local Group dwarf Reticulum II shows abnormally high abundances of r-process and the most likely explanation appears to be a SINGLE neutron star merger "poisoning" the entire population
<SnoopJeDi> UmbralRaptor, dunno what those are :v
<egg|zzz|egg> !wpn UmbralRaptor
* Qboid gives UmbralRaptor an Agile chromatograph
<UmbralRaptor> !wpn egg|zzz|egg
* Qboid gives egg|zzz|egg a magic bustard
<UmbralRaptor> !acr -add:HPF Habitable Planet Finder
<Qboid> UmbralRaptor: I added the explanation for this acronym.
<UmbralRaptor> !acr -add:NEID From the Tohono O'dham word for "to see" (confusingly, this is not an acronym)
<Qboid> UmbralRaptor: I added the explanation for this acronym.
<SnoopJeDi> so we had back-to-back talks actually (who the hell thought this was a good idea?)
<UmbralRaptor> SnoopJeDi: high precision spectrographs. HPF is an IR one that will go on the Hobby-Eberly telescope.
<UmbralRaptor> NEID is optical, and will go on the WIYN.
<SnoopJeDi> second one was quite disorganized, but the speaker was a lovely German fellow with lots of stories about Wheeler, Gödel, and so on
<UmbralRaptor> SnoopJeDi: like at a conference?
<SnoopJeDi> he showed us a photo of his signed copy of Misner/Thorne/Wheeler
<UmbralRaptor> (back to back talks)
<UmbralRaptor> shoby
<SnoopJeDi> Whence Thorne signed "Don't believe everything you read here"
<UmbralRaptor> shiny
<UmbralRaptor> Hah!
<SnoopJeDi> And I think Wheeler wrote "We will first understand how simple the universe is when we realize how strange it is."
<SnoopJeDi> But it's difficult to tell if that's a quote he's sort of known for or a one-off
<SnoopJeDi> UmbralRaptor, the second speaker was hosted by our local quantum optics fellow who is...well, divisive.
<UmbralRaptor> how so?
<SnoopJeDi> His institute just installed a card-swipe access lock to our 5th floor, because nothing says community like "screw you, grad students, these are *our* chalkboards"
<SnoopJeDi> Just the usual big personality that comes with success and money, UmbralRaptor
<SnoopJeDi> Same guy who pulled out a crisp $100 bill to give to Robert Byer to settle a bet about accelerators on a chip
<bofh> SnoopJeDi: holy fuck. but apparently supernova mergers do disproportionately generate most of our heavy elements.
<SnoopJeDi> ("I bet you $100 you'll never give a colloquium on this subject," he allegedly said back in the 70s)
<SnoopJeDi> bofh, I don't grok enough of it to really sort out SN vs NS, but I found the quirky story of an early merger influencing the ENTIRE HISTORY of a very nearby object very compelling
<SnoopJeDi> Perhaps it's common since their populations are quite small to begin with, but it feels...like something special. It made me feel nice to know a story like that about Home.