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10:00 PM
The big goal is to talk about Log and 1/z and complex exponentials not working the way you want to.
 
@TedShifrin Yeah I assumed that's the story Mike wanted to say
 
We're thinking about 1/z on and off as we go forward, so on Thursday they will see it doesn't have an antiderivative on C - 0
 
The pesky $d\theta$ thst isn't exact.
 
Hey guys
 
@TedShifrin The Laurent of Laurent series is less catchy
 
10:01 PM
Taylored joke, 2/10
 
LOL ... Hey, Demonark.
 
Hello
 
Hi @Amin
@MikeMiller @TedShifrin Here's a similar type of mindfuck example: $1+z^2$ has no logarithm in $\Bbb C \setminus [-i, i]$, but it has a square root. Obvious if one knows theory, not so easy otherwise.
 
@BalarkaSen Cant find a maclaurini pun
@BalarkaSen I'm very fond of this example yeah
 
Yeah I had to draw my friends the Riemann surface to explain this
@MikeMiller Old Maclaurin had a germ, $\sum_{n = 0}^\infty f^{(n)}(0)/n!\cdot z^n$
(Sorry)
 
10:06 PM
Groan.
 
The guy's name was Colin Maclaurin, that's pun in itself, come on
 
@BalarkaSen Sorry that I am asking this, How you posted a graduate level posts on MSE while you was an undergraduate?
 
What about high school?
 
@C.F.G Just generally curious about math, I guess.
 
People would be better off if they never compared themselves to other students
 
10:09 PM
@TedShifrin ؟
 
Took me a decade to learn
 
It actually becomes clear if you compare yourself to John Pardon
(That you would be better off not doing so I mean)
 
Ah, it's 5, time to drink
 
What’s a 2 by 1 vector
 
Transpose of a 1 by 2 vector
 
10:11 PM
Classic Daminark
 
Duh
 
Usually n\times m means n rows and m columns
 
Yeah thanks 😊
 
You're ahead of me, @MikeM.
 
@AminIdelhaj (Take the elevator and walk down the hallway)
 
10:12 PM
@MikeMiller RE: Took me a decade to learn: Do you meant from undergraduate to PHD or ?
 
I mean it took me 10 (maybe 15) years of life being self conscious about other people's skills before I realized that is counterproductive.
Those 10-15 years were not exclusively spent in my undergrad or PhD, no, it's just a general life phenomenon that people are too quick to compare achievement to others
 
@MikeMiller: Well, I remember that once I asked my topology professor that what is the intuitive meaning of "compact space" he answered that "it has no intuition and is abstract". This happened to me a lot. And the result I am self-study from beginning after 8 years.
 
That is probably better than learning from someone that does not have an intuition for compact spaces. :)
 
Having advisers who were in the top whatever percent of math for the 20th century taught me fast. I knew I was nothing.
6
 
When did you discover that math was big?
 
10:20 PM
We are like attack ships on fire off the shoulder of Orion, or C-beams glittering in the dark near the Tannhäuser Gate. Soon to be lost in time, like tears in rain
 
@MikeMiller But most of undergraduate students rely on their eyes.
 
Is that an original poem?
 
Nope, it's from the original Blade Runner :)
I modified a little of course
 
@BalarkaSen Oh that's slick
 
@C.F.G I do not follow the metaphor. I will admit I need my eyes too. I would not do well as a blind man.
 
10:22 PM
I discovered that math the realm was big about 3 years ago when
 
Maybe if I became blind I'd be able to learn sphere eversion
Correlation => causation and all that
 
Haha
Morin is a serious legend
 
What
Is left
Multiplication
 
geocalc I feel like I've heard you ask functional analysis questions before unless I'm very much confusing you with someone else
 
@MikeMiller: So What is your opinion about Pontryagin and Euler both were blind?
 
10:24 PM
Wait they were?
 
Euler became blind over time I think
I didn't know Pontryagin was blind. Interesting
 
@AminIdelhaj I’ve asked 1 or 2 func anal questions yes
 
I'm not sure what an opinion on that matter is.
I trust you that it is true
 
Milnor's book preface: Pontrjagin's many contributions to mathematics are the more
remarkable in that he is totally blind, having lost his eyesight in an
accident at the age of fourteen.)
 
That’s unfortunate
 
10:28 PM
I can't imagine it that how he learnt math did high level research.
 
Somehow asking about functional analysis and then not knowing what left multiplication is feels mildly sus to me
 
Sus
Mildly
 
Oh speaking of prefaces
So there's this algebraic number theory book which in the preface has one of my favorite lines of all time
 
I asked beginner function analysis question
Very beginner
 
"The editors must emphasize, however, that neither the lecturers nor the note-takers have any responsibility for any inaccuracies which may remain: they are an act of God."
 
10:32 PM
I will become an expert in left multiplication in 4 years
I’m left handed so that should help
 
Is there a $C^2$ map $f: R\to R$ such that $f''(0)\neq 0 $ and $f'(x)=f(x+1)-f(x)$?
 
Pony tragic was blind. He did not have the duality of blindness
So what is left multiplication?
 
Multiply on the left
 
I contest that.
 
x -> ax
 
10:42 PM
interestingly, the mirror image of left multiplication by c is not right multiplication by c
 
Ok yeah you’re right. Was just checking that you knew as well
 
rather it is right multiplication by ɔ
 
lol
 
Lo f-omg lol
I should not have drunk a vat of coffee
 
good luck
 
10:46 PM
Am I going to be ok
 
@C.F.G I don't have a solution, but by the mean value theorem, every value of f'(x) must occur infinitely often
so my first guess was looking at sines/cosines to get such a function, if it exists
 
Son back to left multiplication
So*
Let’s multiply a 2 by 1 vector by a 2 by 2 matrix
And let’s act on it by left multiplication
What geometric information do you get from thus
0
Q: Composition of two matrix transformations

geocalc33Consider two matrices acting on points in $(0,1)^2$ in the real plane, $$h_s=\begin{pmatrix} e^{-e^{s}} & 0 \\ 0 & e^{-e^{-s}} \end{pmatrix}.$$ and $$g_s=\begin{pmatrix} 1-e^{-e^{s}} & 0 \\ 0 & e^{-e^{-s}} \end{pmatrix}.$$ How do you compose these transformations? I tried to do $h_s...

More detail
 
11:35 PM
This equation is throwing me off a bit:
$$
\int_{a}^{\infty} p\left(y, s \mid v^{\prime}, t^{\prime}\right) L_{y} p(v, t \mid y, s) d y=\int_{a}^{\infty} p(v, t \mid y, s) L_{y}^{*} p\left(y, s \mid v^{\prime}, t^{\prime}\right) d y
$$
Here, p is a conditional density
Here, L is the differential operator from the fokker-planck equation
$$L g(x):=\frac{1}{2} \sigma^{2}(x) g^{\prime \prime}(x)+f(x) g^{\prime}(x)$$
And its adjoint is $$L_{y}^{*} g(y)=\frac{1}{2}\left(\sigma^{2} g\right)_{y y}(y)-(f g)_{y}(y)$$
What space is the operator defined on, and what is the reference inner product?
Is this with reference to L^2? That would explain how one switches around in the integrals
Ah yeah this is more simple than I expected, the notation threw me off. It's just the adjoint property w.r.t. L^2
 
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