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00:00 - 19:0019:00 - 00:00

19:01
No. A left or right inverse may exist, but it will not be two-sided since the dimensions will be wrong.
@Zibadwa Many statistical methods require me to use inverse like the Mahalanobis Distance. How should I proceed in such cases?
See this equation which represents the Bhattacharyya Distance
19:30
any help please
Can someone, by any chance, have look at this math.stackexchange.com/a/102888/59219 ? In particular, why does this equation $ \lim\limits_{h\to 0}\frac{\overline{f(\overline{z+h})}-\overline{f(\overline z)}}{h} =\lim\limits_{h\to 0}\overline{\left( \frac{f(\overline z+\overline h)-f(\overline z)}{\overline h} \right)} $ hold?
test $\LaTeX$
It's just the definition and properties of complex conjugation.
but why $h$ become $\overline{h}$?
Ok, I get it now. It's just properties of complex conjugation http://en.wikipedia.org/wiki/Complex_conjugate#Properties. Thanks.
19:54
You're welcome.
@SohaibI Not my area of expertise. Looks like you can't. Determinants don't even make sense over non-square matrices. At best you could perhaps use some of the matrices from a SVD, as a rough non-expert guess.
20:17
-1
Q: Changing cylindrical coordinates to cartesians's

pourjourI was wondering how to find $e_r$ using $e_x$ and $e_y$ as you can see in the scheme: So what I really want is to prove that: with a deep proof using maths

Senior Math Challenge tomorrow
must learn divisibility by all primes under 20
@Zibadawa Thanks. I found another method using cholesky factorization that works.
But now an error pops up saying matrix must be positive definitive.
My 60 x 120 matrix has currently elements from -1 to 1 with two rows columns as completely zeroes.
If I scale it between 0 and 2 will it have an impact on my overall result?
20:49
@PedroTamaroff You know the series I derived from the gamma function like integral
@robjohn How do we know the integral in $(9.10)$ here has no poles?
Sorry, I just linked here! Here is the right link: nhn.nhn.ou.edu/~milton/p5013/zeta.pdf
21:10
@Argon Does it not explain in the paragraph below?
@Alizter I know the Gamma function introduces poles and I know that the integral must converge at least for $s > 1$. What about the rest?
Is there a standard technique to prove an ideal is prime in a multivariate polynomial ring? Specifically, I'm trying to show the principal ideal generated by $y^2-x^2(x-1)$ is prime in $F[x,y]$ where $F$ is an arbitrary field.
@Argon What rest?
@Alizter $s < 1$
It says a contour that encloses 0
21:17
So? The contour is not closed, there is even a branch cut through it
@Argon TBH I have no idea sorry
No problem
21:37
@AlexanderGruber had problems for me!
Where are they?
@PedroTamaroff Have you checked the two conveniently placed empty warehouses with barrels of oil in them?
@Alizter That's suspicious.
=)
Now I have to go.
@Argon @Charlie Ask Alexander°!
@PedroTamaroff ask what? I'm confus
Grubby doesn't show up here too often
@Alizter ali, what is Pedro Nicolás talking about?
21:53
He lost them.
user96977
is the kernel of a homomorphism $\theta = ${$g \in G | \theta(g) = 1$} a normal subgroup of $G$?
@Alizter lost whom?
I have no idea. We are talking crap.
@Alizter you guys...
hey guise
22:04
@TruthSerum Indeed.
22:33
Oi @leo
leo
leo
@Charlie hellow
yello
@TruthSerum Yes. In fact, that is how normal subgroups arise.
As kernels of homomorphisms.
@PedroTamaroff pedro nicolás!
@Charlie Heya.
@PedroTamaroff how are you?
@PedroTamaroff I misspoke, I should have said integral domain, not field
also hi @Charlie
23:09
@anon Yeah, just realized =P
@anon hello
It is weird the edit doesn't show up!
@anon How are your diff. eqns. doing?
eh, why?
forgot how to solve $ax^2y''+bxy'+cy=f(x)$ until the last second on my test
@anon Dunno, just small talking man =)
@anon Euler!
yes
23:20
@Pedro @anon!
@anon What kind of course is that one? Do you dwell into the theory? Because the theory of diff. eqns. is pretty nice!
@TedShifrin Helloes!
We never dwell!
@TedShifrin What?
Re your query @anon
@TedShifrin Ah.
23:23
Last time I taught that stuff was first year of grad school... I.e., a millennium ago.
@PedroTamaroff no, it's not at the level where you would dwell on things, only at the level where you memorize grab-bags of handy tricks
@TedShifrin Hehe, I am thinking about reading a book by Coddington and Levinston.
@anon Ah. So I am guessing you're not too thrilled about it.
nah
@anon Gusfrava.
Birkhoff/Rota and Hirsch/Smale are good books. Particularly the latter.
23:27
@TedShifrin Googles.
You google me alot, @Pedro!
@TedShifrin Well, yeah!
"DIFFERENTIAL EQUATIONS, DYNAMICAL SYSTEMS, AND AN INTRODUCTION TO CHAOS"
Better than ogle, I guess :)
The chaos stuff was added by Krantz in the latest version, but the old ones are great.
@anon
Today I was given a nice argument that $\Bbb Q[\sqrt 2+\sqrt 3]=\Bbb Q[\sqrt 2,\sqrt 3]$
In fact, two.
its conjugate is its inverse, then (anti)symmetrize
23:31
@anon Yes, that is what I used.
So three solutions so far. =P
So, it is readily seen that $\Bbb Q[\sqrt 2+\sqrt 3]\subseteq \Bbb Q[\sqrt 2,\sqrt 3]$,
Dinnertime. See y'all later.
@anon Now give me a sec, this surpases my TeXing.
@anon
Now, we know that $d$ cannot be $1,2$ or $3$, so $d=4$, $d'=1$ and done.
@Clayton !
23:47
@PedroTamaroff: Haha, nice clip.
@Clayton (The guy with the gun is named Clayton.)
Ah hahahaha, now it has purpose. I was confused as to the relevance. I didn't know I was famous
@Clayton Never watched Tarzan? It is one of the best movies of my childhood. =)
@PedroTamaroff: I have seen it, but it has been so long since I've seen it that I hadn't remembered.
Is anyone in here that likes a bit of algebra in multivariate polynomials?
@PedroTamaroff I just thought of that when I read his name :)
23:57
@Charlie =D
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