egg|nomz|egg changed the topic of #kspacademia to: https://gist.github.com/pdn4kd/164b9b85435d87afbec0c3a7e69d3e6d | Dogs are cats. Spiders are cat interferometers. | Космизм сегодня! | Document well, for tomorrow you may get mauled by a ネコバス. | <UmbralRaptor> egg|nomz|egg: generally if your eyes are dewing over, that's not the weather. | <ferram4> I shall beat my problems to death with an engineer.
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<egg>
UmbralRaptor: uh what is I_RZ supposed to mean
<egg>
UmbralRaptor: I was talking about computing I_11 through I_33 with the given axes for x1 through x3, just *doing the integration* in cylindrical coords
<UmbralRaptor>
ah
<egg>
UmbralRaptor: like, moments of inertia along an axis tend to require an axis, so I'm not sure what I_RR is supposed to mean
<egg>
there's no R axis
<egg>
UmbralRaptor: so, like, <egg> UmbralRaptor: well then shrug, x1 = r cos φ, x2 = r sin φ, dV = r dφ dr dx3, sum for x3 ranging from 0 to h, for r ranging from 0 to R x3/h, for θ ranging from 0 to 2π of what you said
<egg>
UmbralRaptor: just use your formula for I_ij (just don't do an integration in cartesian coords over a cone because that sounds unpleasant)
<egg>
UmbralRaptor: and reorder your integrals to integrate over the angle first
<egg>
UmbralRaptor: you should immediately see that the off-diagonal entries vanish
<egg>
UmbralRaptor: do you see what I mean
<UmbralRaptor>
okay, I can see I_xy = 0, but I have an error somewhere in I_xx
<egg>
UmbralRaptor: so the integrand is (r^2+x3^2-x1^2)r, right? (where the outer r is from the volume element)
<egg>
(and there's the density but let's just factor that one out or set it to 1 or something)
<UmbralRaptor>
yeah
<soundnfury>
egg: just use naturalised units ;)
<soundnfury>
(that's how those work, right?)
<UmbralRaptor>
I set up the integrand wrong.
* UmbralRaptor
gives soundnfury an unnatural unit system. (probably designed by goblins)
<soundnfury>
thanks, I _love_ British Imperial units :)
<egg>
iirc those goblinoid units were rather weirder
<egg>
there was a two-ell telescope
* UmbralRaptor
heats soundnfury with a Baker's dozen of international British thermal units.
* soundnfury
recalls the time a rocket scientist measured s.h.c. in BTUs per lb Rankine
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<soundnfury>
egg: A law of King Edward I required that every town in England had an ellwand. (Source: wiki)
<egg>
UmbralRaptor: are there lines
<egg>
in the unnatural units
<UmbralRaptor>
Yes, but if they're 1/10 of an inch, it's probably not an avoirdupois inch.
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* egg
staring at the kspd&d backlog
* UmbralRaptor
does not give egg a three line rifle.
<soundnfury>
… is that where three-line whip comes from?
<UmbralRaptor>
?
<soundnfury>
… according to wiki, no. It refers to the number of times the !instructions are underlined.
<egg>
UmbralRaptor: ah yes there were bennettitalean seeds as units in that kspd&d thing
<egg>
UmbralRaptor: <egg|zzz|egg> the hadrosaur is tired and decides to sleep despite being glowy
egg is now known as egg|zzz|egg
<egg|zzz|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor an ultramatic planet
<UmbralRaptor>
uh
<soundnfury>
!wpn egg|zzz|egg
* Qboid
gives egg|zzz|egg an unitary reflector
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<egg|zzz|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a [DATA EXPUNGED] neutron diagram which strongly resembles a group
<UmbralRaptor>
x_x
<UmbralRaptor>
>_<
* egg|zzz|egg
pets UmbralRaptor
* UmbralRaptor
doesn't see a way to complete this homework.
<egg|zzz|egg>
what, the cone?
<egg|zzz|egg>
UmbralRaptor: don't you have the entire matrix?
<egg|zzz|egg>
and then just parallel-axis it to the centre of mass
<egg|phone|egg>
Z
* UmbralRaptor
ha been making lots of algebra errors.
* UmbralRaptor
integrates the Z from 0 to h.
<egg|phone|egg>
Zz
<egg|phone|egg>
Zzz
<egg|phone|egg>
zzZ
<UmbralRaptor>
zZz? ☡☡☡? ζζζ?
<egg|phone|egg>
Did you get i11
<UmbralRaptor>
yeah
<egg|phone|egg>
Yay
<egg|phone|egg>
So i33 is already a principal moment
<egg|phone|egg>
You just need to parallel axis the other
<egg|phone|egg>
Which requires finding how far down the centre of mass lives
<egg|phone|egg>
Which is triangles
<UmbralRaptor>
revolutionary triangles
<egg|phone|egg>
Barycentre, 2/3h down
<egg|phone|egg>
UmbralRaptor, yeah but their Revolution matters not
<egg|phone|egg>
Wait
<egg|phone|egg>
No I'm stupid
<egg|phone|egg>
It does
<egg|phone|egg>
I should sleep
<egg|phone|egg>
!Wpn UmbralRaptor
* Qboid
gives UmbralRaptor a triacontahedron anaconda
<kmath>
<kevinschawinski> Hi @gaylordnational @Marriott why did you just increase the rate of my confirmed reservation without telling me? cc… https://t.co/0q9Mn6FaDW
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* UmbralRaptor
still isn't sure whose idea it was to host the biggest astro conference in the US at such an expensive chain.
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UmbralRaptor is now known as NomalRaptor
<egg|work|egg>
!wpn NomalRaptor
* Qboid
gives NomalRaptor a quokka
<egg|work|egg>
NomalRaptor: how is your cone doing
<awang>
Someone here says that C# is interpreted down to bytecode
<Qboid>
4d 0h 0m 0s left to event #17: et al./Falcon 9 v1.2 [at 2017-12-08 18:20:00]. Say '!kountdown 17' for details
<awang>
And "compiling is a destructive process, interpreting isn't"
<SnoopJeDi>
The first statement doesn't really make sense, but this is that sticky issue of most "interpreted" languages not really being interpreted at all
<SnoopJeDi>
e.g. Python
<awang>
SnoopJeDi: In what way?
<awang>
Genuine question
<SnoopJeDi>
All the implementations people mean when they say "Python" are compiled to VM bytecode
<SnoopJeDi>
You *can* interpret Python, but I'm not aware off the top of my head of any implementations people actually use that do this?
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<SnoopJeDi>
anyway, AFAIK (I do not write it) C# is the same way, you compile for a VM and run it there, which makes sense because C# is very Java-like and Java runs on the JVM
<awang>
OK, that's what I thought
<SnoopJeDi>
I don't know what that person means by "destructive," but compiling can certainly mutate the patterns as writ in the human-readable code. Usually because the human did something stupid. Compiler design is all about doing this without changing the "content" of the code, but we're dangerously close to things I don't know about.
<egg|zzz|egg>
!wpn bofh
* Qboid
gives bofh an impedance-matched ███████
<egg|zzz|egg>
!wpn whitequark
<SnoopJeDi>
but like, yea if you write unreachable code, a compiler is likely to "destroy" that because there's no point carrying it around
* Qboid
gives whitequark a zeta implosion
<egg|zzz|egg>
!wpn Fiora
* Qboid
gives Fiora an IEEE 488 scream
<egg|zzz|egg>
!wpn котя
* Qboid
gives котя a chocolate dip pen
egg|zzz|egg is now known as egg
<egg>
!wpn NomalRaptor
* Qboid
gives NomalRaptor a neptunium hydrargentium density
egg is now known as egg|nomz|egg
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<egg|nomz|egg>
awang: can you try making a journal for your krash crash? I don't think we'll be able to diagnose it without that