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22:17
hey math people, I was just wondering if you would like this question from Physics:
0
Q: volume charge density of hydrogen atom

user17574The potential of the hydrogenatom is given by: $\phi(r) = \frac{1}{4 \pi \epsilon_0} \frac{e}{r} ( 1 + \frac{r}{a_0}) e^{-\frac{2r}{a_0}}$ I'm no supposed to find the volume charge density $\psi$ which produces such a potential, which conceptually is fairly simple, just slap on the Laplacian fr...

It seems to be essentially mathematical but I'm not sure if it's too homework-y for you.
looks hard
give it here
@DavidZaslavsky, why do you have this physics.stackexchange.com/questions/54985/… but not like the charge density one?
oh I see
@skull Skullito, are you there ?
@user58512 ?
hey @mick
22:28
@Charlie Hi !
@user58512 Hi ! whats up with the satanism ?
I found this but it doesn't seem to help jstor.org/stable/3029387
@mick hi Micky!
@user58512 aha still thinking about the lucky numbers :)
yeah
I was trying to think if there was something like a mobius function for it, but I got nothing
In fact I could easily double all my questions by replacing integer or prime with " lucky" but I guess It would not increase my rep much :)
22:32
lol
Just saying this is HUGE
even Goldbach appears true for lucky numbers !
@anon how are you?
alright
@Charlie whats on your mind ?
@mick what I have to do tomorrow... I'm a little dizzy...
22:35
I wonder about this , how do you show the domain of an inverse function is open , or closed ...
@Charlie play DBZ on PS3 ?
dizzy ?
from my questions ? :p
@mick I only have xbox 2$\pi$
Let me give an example of what I mean
@anon Hey
No I'm dizzy, a little weird....
@anon Does this seem right to you? math.stackexchange.com/a/313419/38268
@AlexYoucis Hey
22:38
@BenjaLim Hey
Let f(z) be an entire function , Let f^-1 be the inverse.
@anon Have you done any class field theory?
@AlexYoucis Does my answer seem right here?
is f^-1(z) = real true in (0,1) or )0,1( or )0,1) or (0,1( ??
THAT TROUBLES ME
@mick That doesn't make any sense, but the inverse of a bijective entire function is holomorphic and thus open
22:40
@AlexYoucis I think my answer is right; the left hand side can't be zero
@BenjaLim I'll read it in a minute
@AlexYoucis thanks
@AlexYoucis I think it does make sense.
consider it a branch cut
like sqrt(z) goes to imaginary or such
user19161
@argon How is your weekend?
@AlexYoucis I have to go to class now, but do ping me and I will see your message
22:45
bye
@BenjaLim yes
@AlexYoucis no (besides skim over a definition or two)
@anon I don't understand countinghaus'
answer
@anon I tried yesterday to produce a $K[G]$ - module $C$ such that $\text{Ext}^1 ( K[G]/U ,C ) \neq 0$
Put another way : let f be continu at (0,2) apart from a discontinu point at 1. If f is constant at (0,1( how to prove (IN a case where it is true) that f(1) is the same value as f(0) ?
In other words , when I know there is discontinu point , i want to know the output value
@user58512 do you understand what i mean ?
@Charlie are you sick ?
@BenjaLim Since U is the kernel of tr:K[G]->K, in order for K[G]=U(+)V we must have V iso to K as a G-module, which means V must be generated by a G-invariant element of K[G], and such a thing has equal coefficients hence trace zero hence is in U, contrary to the assumption of directness of the decomposition of K[G] into U and V.
I am not familiar with Ext, Tor, etc
@BenjaLim What course are you taking now?
22:49
@user58512 because the one you linked is about physical intuition, whereas the hydrogen atom one is just math (just asking how to solve an equation).
I want to know if the range of f(z) = c is open or closed or half-open ...
I fear that question is too general , but I want an answer :/
I know it can be solved for simple fourrier series ...
@anon you look like a super saiyan ...
indeed
this isn't even my final form
@anon makes sense since you got 35.9 k
thats over 9000
Do you need to go to final form to answer my question or can you answer now ?
ping me if you are still awake people !
:/
@anon what does that mean ?
23:01
it's the mckayla face
you might as well answered 42 :)
How do I enable chatjax ?
@anon I understand the question is general , but I would like some quite general techniques to solve such questions. That is assuming you understand what I said or maybe better stated : Assuming I made myself clear.
never mind, I got it
@GitGud hi
23:05
@mick Yo.
@mick the singleton set and interval {c}=[c,c] is closed. I am assuming you are looking at the range of a constant function f(z)=c.
closed in the complex plane, too, if c is complex (no longer really an "interval" then though)
Lets say f( (0,1( ) => A and f( )1,2) ) => A where A is a connected set.
How do I FIND f(1) ??
I cannot understand your notation
are you saying the images of (0,1] and [1,2) under f are both some connected set A?
@anon (0,1( is a halfopen interval and )1,2) is a halfopen inteval
@anon yes
I've never seen that notation used before
23:12
and now I want to know f(1)
it is not uniquely determined; are you looking for the subset of A of possible values for f(1)?
yes
btw connected means a curve in the complex plane here
and f is a riemann surface
I am not familiar with riemann surfaces
but my opinion is that f(1) can be anything in A in general
ok then lets say f is the inverse function of an analytic function
yes , but if f is given , how to find f(1) ?
plug in 1
23:17
but at 1 there is a discontinuity
so its numerically unstable
we've gone from pure theory to numerical approximation. I feel you are taking me on a goose chase.
No im serious
you gave no indication this was a numerical problem until this point in the conversation. did you seriously not think it relevant?
its a bit like asking how to compute f(1) on a periodic fourrier series with period 1 and a discontinuity there.
@anon I did way in the beginning somewhere
I am not a numerical analyst, so I don't think I can continue at this point
well, those are my just deserts for entering the conversation late, then
23:20
@anon I do not know what that means , my english is not so good sorry
don't worry about it
k
Im trying to come up with a simple example function f , but I cant :/
In order to clarify the question
@JacobBlack Weekend was fine. And yours?
I fear it might be a convergeance on the boundary question :(
Im going offline , maybe Ill be more lucky next time
bye@anon
bye@Charlie
@mick bye
23:27
@robjohn Hey Rob ! maybe you can help me ?
@mick with?
@robjohn a question of course :)
@mick yes, but what question?
Lets say f( [0,1[ ) => A and f( ]1,2] ) => A where A is a connected set (curve on the complex plane) .
How do I FIND f(1) when f is given ?? ( f is the inverse of an analytic function )
@robjohn
can we post links to our questions here? or are we supposed to type the question in chat, if help is required..thanks
23:32
@user52932 you can post a link to your question here , but do not spam :)
I need help with some differential equations stuff dealing with lipschitz....here is the link
2
Q: Existence of Solution to Differential Equations.

user52932$f$ is locally Lipschitz in $y$ if for every $(t_0, y_0) \in (c,d) \times U$, there exists a neighborhood V of $(t_0, y_0)$, (i.e. $V = \{f(t,y) \in(c,d) \times U : ||t-t_0|<a \ \text{and} \ |y-y_0|\leq b\}$) and a constant K = K(V) such that $||f(t,x)-f(t,y)||\leq K||x-y||$ for any $(t,x),(t,...

I have solved some of the problem in the comments on this link, any help would be much appreciated
@mick Is $f$ continuous?
@robjohn yes
@mick Then the limit as $x\to1^-$ should be the same as the limit as $x\to1^+$, yes?
@robjohn No its discontinu
but one of those is f(1)
23:40
@mick Oh, that is why I asked about the continuity. If it is discontinuous, then I don't see how you can find the value. With Fourier Series, the convergence at a discontinuity is the average of the limits from either side.
@robjohn yes I know. But this might not be the case here. that IS my problem
@mick I see that. As I said, I don't see how you can find the value if you don;t know anything about the continuity
@robjohn I have to go , we can continue this later I guess ?
bye
@robjohn ok ?
im off guys
bye bye
Bye.
@mick sure
23:57
@robjohn any chance you could take a look at this for me?
2
Q: Schwartz Reflection Principle -- Mapping across horizontal lines

ArkamisI am stuck on the following problem: Suppose an entire function maps two horizontal lines onto two other horizontal lines. Prove that its derivative is periodic. The author supplies a hint: Assume $f = u+iv$ maps the lines $y=y_1$ and $y=y_2$ onto $v=v_1$ and $v=v_2$ with $y_2-y_1 = c$ and ...

Does chatjax also works on facebook ?
@Kasper If you include the $...$ etc there, then the bookmark will work
@Kasper On Facebook's chat, I think so.
Never tried walls or comments.
@Arkamis let me look
@PeterTamaroff It does work on walls/comments
23:59
Good.
Of course, all your non-math friends will be like "wtf..."

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