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00:00 - 17:0017:00 - 00:00

5:00 PM
@caveman wtf, you say hi back to them but NOT ME!!
 
I've got no idea how to start with it
$$\sum_{k=1}^{\infty} \frac{1}{2^k k^2}$$
 
@caveman: it's the last challenge to me. It just crossed my mind the following" how about proving it elementarily?" :-)
 
I couldn't do it at all, let alone elementary
 
@caveman: my insight tells me that we can do it. Perhaps I need to think of it a bit longer.
 
sorry @greekletters
 
5:03 PM
np
:)
You can call me skullpatrol
 
SKULLPATROL
 
cool
 
@κρανίοπεριπολία ;-)
 
5:07 PM
@caveman its a special value of the dilogarithm
@caveman using some of the functional equations for dilogarithms to solve for it
 
thanks Ethan
 
@κρανίοπεριπολία : /
 
hhh
Do you know how to plot the Joukowski? I am stumbling with Mathematica:

http://mathematica.stackexchange.com/questions/21920/complexmapplotz-1-z-z-circle0-25-0-1-25-with-newer-mathematica
 
$\Huge\text{(}$removed$\Huge\text{)}$
@Charlie what?
 
@hhh sorry, I'm not familiar with Mathematica
 
5:11 PM
@κρανίοπεριπολία oh.... : / kind bored, I don't know...
 
hey :)
 
@Charlie Got bored? Why don't you watch the following?
 
@ManishEarth what brings you here?
 
chat flags
(nothing to worry about)
 
5:13 PM
it's amazing Karl'sstudents
can they realyplay this well
 
@κρανίοπεριπολία rly
 
> Sinistar is a destructive cosmic force. In order to fulfill its goal of total annihilation, it needs a physical host. The only physical form that Sinistar is compatible with is negatively charged Sinisite crystals. Once 20 crystals have been gathered together, the host is complete, and the Sinistar essence fills the structure. From that moment on, it is free to rampage around the galaxy, growing stronger with every destruction.
 
@Karl'sstudents funny
 
5:17 PM
@Charlie The little girl's smile is not natural I think :D
 
Yip yip yip
 
hhh
@Nimza I am trying to understand what the complex plot is: $a,b\in\mathbb R$ so that $z=a+ib$.
 
@Karl'sstudents yeah...."do it or die"
 
hhh
for two 2D where complex is one axis and the real is one axis
-
 
5:19 PM
@κρανίοπεριπολία yep yep yep
 
@κρανίοπεριπολία yap yap yap
 
@hhh what do you want to draw? I thought you want to draw an image of 1-d real curve under such transformation. it is still 1-d curve in plane
 
@Charlie WTF!!! are you telling me I yap too much? Fine I'm leaving >8(
 
@hhh or you want to glue together such Jukowski profiles of wing into a wing?
 
5:22 PM
@κρανίοπεριπολία :(
 
hhh
@Nimza yes trying...

ParametricPlot3D[{xx, yy, k}, {z == x + I*y}, {xx, 0, 1}, {yy, 0,
1}, {k, 0, 1}]
(fail)
 
@hhh I don't know how to deal with Mathematica, but maybe you should use Re and Im somewhere in this string?
 
@κρανίοπεριπολία what about the context stuff?
 
@hhh for example if I have 1d array of complex numbers that represent curve in Matlab I plot it with plot(real(z),imag(z))
 
@Charlie Very good. Now you know I was being sarcastic ;-)
 
5:27 PM
@κρανίοπεριπολία ;)
 
$\Huge\text{Context}$ is everything.
and sometimes yyp yyp yyp
 
@κρανίοπεριπολία however, we can hide out intentions inserting them into a context, true, but we still can give another meanings that transcends the simple context, using it as an excuse to day what we actually wanted. Not that I meant that.
 
Hi @anon @seaturtles
@Charlie True, I was just trying to make a point that by taking things out of context you can change their meaning, right?
 
hhh
@Nimza How would you plot with an implicit function like J(z)=z+1/z?
 
@hhh I will obtain an array of values $\{ J(z) \}$ and since it locally preserves order of points I will plot it
 
hhh
5:41 PM
@Nimza so your k coordinate (up coordinate) is J(z) and z=x+yi so x is the x-coordinate and y is the y coordinate?
 
@hhh hm, why? I will just plot plot(real(J(z)),imag(J(z)), where $z$ is an array of points giving a circumference
@hhh if you want a graph you can surf(real(z),imag(z),real(J(z)),imag(J(z)) where z is a matrix giving a 2d region in $\mathbb{C}$
 
hhh
@Nimza what is the matlab command you use?
 
@hhh i've written it, just plot
 
hhh
@Nimza you use the symbolic toolbox in matlab?
 
hehe, let me run Matlab, one moment
 
hhh
5:45 PM
syms z
 
no, numerically
 
hhh
Can you share some small demo?
I have matlab to try...
 
okay, what you want to do?
 
hhh
I want to see just a plot with complex numbers -- it would be cool to see the J(z)=z+1/z
 
good
 
5:48 PM
or sin(1/x)?
 
you cant plot a complex valued complex function
you could plot it's image but not it's graph
 
`phi = linspace(0,2*pi,200);
z = -0.1 + 0.4i + 0.8*exp(1i*phi);
w = z + 1./z;
plot(real(w),imag(w));
`
 
cause the graph is a subset of IC x IC which you need to plot as IR^2 x IR^2
 
multiply by 1/2
@DominicMichaelis yes, but surf provide coloring option, so you can visualize fourth dimension by color
 
that is quite sensesless as colors only makes sense in a 2 dimensional plot
 
5:56 PM
is not a graph of a number just a point?
that is paired with the number
 
@κρανίοπεριπολία haha, a graph of number in $\mathop{\mathrm{Spec}} \mathbb{Z}$ not :D
 
@skullie the problem is that our points are already 2 dimensional, like our numbers
in a very non strict way spoken
 
@DominicMichaelis for example color is very useful of you plot graph of $z \mapsto \sqrt{z}$
 
but her you use two graphics, one for the real part one for the imaginary don't you ?
 
5:59 PM
no
 
@κρανίοπεριπολία absolutely
 
I select 2 lines
for example re and im, values on second are colors
 
I am hungry.
 
and I use projections of my function image on second as colors of graph
 
could you make a screenshot, i hardly believe that you can see a lot there
 
6:01 PM
aha
 
@Charlie so context is a very important avenue to deliver meaning (as shown by your quotes in the zone)
 
hhh
@Nimza How did you choose the initial point?
 
@Charlie all of which were taken out of context, correct?
 
@DominicMichaelis without colors it is a messy kitchen
@hhh heuristically :)
 
6:05 PM
every plane is a line right?
 
@Russian guy Hey.
*Greek apparently
Looked like cyrillic to me.
 
@DominicMichaelis hm? x-axis is real part of argument, y-axis is an imaginary part of argument, z-axis is a real part of function value, color is an imaginary part of function value
 
@GitGud That's skullpatrol in Greek :)
 
Oh, hi.
 
6:06 PM
@κρανίοπεριπολία I understood what you meant, okay? :)
 
@Charlie Now did you, really?
 
@DominicMichaelis sorry, I'm going to eat now
 
@nimza enjoy your meal
 
thank you))
 
@κρανίοπεριπολία OF COURSE :-S
 
6:11 PM
@Charlie Are you intentionally "SHOUTING" at me? :(
@Charlie If so, I apologize for offending you.
Good bye.
(removed)
 
@Nimza Did you use ImageMagick to make the GIF?
 
what happened to the link in mse main?
 
hhh
Can you try circle as initialization like this

ComplexMapPlot[z + 1/z, z, {Circle[{0.25, 0}, 1.25]}]
 
The last message posted by skullpatrol
 
@κρανίοπεριπολία enough of jokes, please, enough of "I'm showing you that quoting me pure and simply didn't mean anything because its out of context" I repeat: I fucking understood what you said.
2
 
6:20 PM
 
Am I the only having an issue with this question: math.stackexchange.com/questions/338961/… ?
 
@PeterTamaroff hey dude, wassup?
howz algebra coming off?
 
@GitGud i am a bit confused too
 
@JayeshBadwaik Cool, for the time being.
 
Has anyone seen house of cards?
 
6:22 PM
I'm just chilling now.
 
what is the name of the symphony?
 
@PeterTamaroff I see. nice.
 
@DominicMichaelis There are two answers already. WTF? I can't even understand the question.
 
isn't marvis answers tautological ?
 
did you mean circular
 
6:28 PM
jupp
 
no, it's a valid proof
 
@DominicMichaelis so funny :)
 
@peter why you removed your comment ?
 
@DominicMichaelis I don't wanna be startin' somethin'.
 
@PeterTamaroff yeah yeah
@jasper hiiii!
 
6:38 PM
@peter i guess my way is more elementary anyway
 
@DominicMichaelis I upvoted you. I didn't upvote Marvis.
 
i didn't upvote marvis either, i think his way is cheating a bit
 
it's called mathematics
 
well he is saying it needs to make sense hence it is that way
 
@caveman mathematics is cheating?
 
6:48 PM
@DominicMichaelis he is using so many concepts at once, it is difficult for his argument to not be circular, so I agree with you.
 
7:07 PM
@JasperLoy Thanks. =)
@Karl'sstudents Mathematical sense. XD
 
Is there a moderator around?
 
@GustavoBandeira Just another one you might have NOT seen before.
3 hours ago, by Karl's students
user image
 
@GustavoBandeira Do you need me to zoom in the crucial part and trim the other parts?
 
Crucial parts?!
 
7:11 PM
@GustavoBandeira The tongue and its vicinity.
 
Haha
:8653006 Krakka Kaka kab... Cabbage.
 
@κρανίοπεριπολία: please undelete your previous comment. I want to read it.
 
@Karl'sstudents There is no "undelete."
 
@κρανίοπεριπολία You can make a new same one.
@Potato robjohn with yellow avatar is our mod.
 
7:28 PM
@Karl'sstudents
undeleted.
 
@κρανίοπεριπολία Hm... looks like batman's ears.
 
OK folks, it is enough for playing. Let's talk some mathematics problems.
 
user19161
This site has strange meta questions.
 
Is there a good free tutorial about "necessary", "sufficient" conditions, and its variant ?
@JasperLoy What is the question?
 
user19161
7:32 PM
@Karl'sstudents Many of them are strange.
 
user19161
@Karl'sstudents What do you need to know?
 
@JasperLoy For example?
 
user19161
@Karl'sstudents Never mind.
 
@JasperLoy Oh I have watched it. John Nash!
 
@Karl'sstudents What do you need to know?
About "necessary", "sufficient" conditions, and its variant ?
 
7:44 PM
@κρανίοπεριπολία Definitions and examples.
 
@Karl'sstudents Start with a College Standard Dictionary.
 
@robjohn Could you ping me when you get back? I need to talk to a mod.
 
@jasper hi!
@Karl'sstudents Hi
:'(
 
@Charlie Yes, I do like the autumn wind.
 
@κρανίοπεριπολία Great!
@κρανίοπεριπολία and this?
 
8:00 PM
@Charlie Entertaining... but like you: "not a fan though."
 
@κρανίοπεριπολία rating please
 
oh
 
...passes on entertainment value only...
 
@κρανίοπεριπολία what about this?
 
8:04 PM
8 because it made her a star.
 
@κρανίοπεριπολία :)
 
@κρανίοπεριπολία what, my smile?
 
i always have the feeling if you say am - gm you get at least 5 upvotes
 
@κρανίοπεριπολία agree
 
8:06 PM
@DominicMichaelis duuude, you have to agree, it was a very cool solution. :-)
 
yeah for sure
 
@κρανίοπεριπολία and this?
¿quién me va a entregar sus emociones?
¿quién me va a pedir que nunca le abandone?
¿quién me tapará esta noche si hace frío?
¿quién me va a curar el corazón partío?
¿quién llenará de primaveras este enero,
Y bajará la luna para que juguemos?
Dime, si tú te vas, dime cariño mío,
¿quién me va a curar el corazón partío?
 
@Charlie Sorry I can only rate English songs, but the tune/melody is nice...
 
@κρανίοπεριπολία cool, it's one of the few spanish songs i like, because i usually don't like them.
Who is going to deliver your emotions?
Who is going to ask you to never give up?
Who clog me tonight if it's cold?
Who is going to heal this broken heart?
Who will fill the spring this January
And the moon will fall for us to play?
Tell me, if you go, tell me my dear,
Who is going to heal this broken heart?
 
...7 for tune/melody.
 
8:12 PM
@κρανίοπεριπολία good, fair
 
@κρανίοπεριπολία ^that was the translation
 
Thanks.
The video is a bit "unimaginative,"
in that they only use the standard romantic symbols repeatedly.
 
@Potato yes?
 
8:20 PM
@κρανίοπεριπολία yip
@κρανίοπεριπολία I don't like spanish...shhhhh
 
@κρανίοπεριπολία it bothers me....
 
@κρανίοπεριπολία i dunno, i don't like its sound
@jasper hi
 
user19161
@Charlie Hello.
 
8:22 PM
@JasperLoy :D
 
got 99 upvotes on calculus and 97 on real analysis i guess in some days i get the tag badge for them :)
 
user19161
@DominicMichaelis Ah, I usually don't care about badges!
 
i am just excited about the first fancy red one :D
 
8:38 PM
@Robjohn, is there somewhere we can talk privately?
 
@Potato invite him to a room :)
 
user19161
@Potato Hello! I like to eat potatoes.
 
@JasperLoy me too!
 
user19161
9:18 PM
@DominicMichaelis That is not private, everyone still can read.
 
@JasperLoy: I am writing a free tutorial on PSTricks and I need some native English speakers to proofread it voluntarily. :D Do you have any idea?
@JasperLoy: Or you want to participate?
 
user19161
@Karl'sstudents Hmm, sorry, don't want to proofread this.
 
oh...
 
@JasperLoy Oh my ghost!
3 centuries later...
 
@Karl'sstudents OH NOES!
 
9:35 PM
The last message was posted 1 year ago...
 
Hello mathematicians!
I have a question
 
ask
 
Given 2 foci and 2 arbitrary points, can we construct its equation?
be careful, I am talking about rotated ellipse .
 
hello
what do you mean 2 arbitrary points?
 
0
Q: How to draw an ellipse if 2 foci and 2 arbitrary points are given?

Karl's students How to draw an ellipse if 2 foci and 2 arbitrary points are given?

 
@Karl'sstudents obviously not, take two points symmetric to a focus
 
@Karl'sstudents
what do you mean 2 arbitrary points?
 
@caveman any points on the ellipse
 
so if you have two foci: F_1 and F_2 and a point P on the ellipse
 
9:55 PM
you only need one point
 
the distance k from F_1 to P is equal to the distance k from F_2 to P
and the equation of the ellipse is the points P where distance(F_1,P) = distance(F_2,P) = k
 
@caveman if both distances are the same we can't have arbitrary points
as just take one of the points of the line where the focis are on
 
everything I said was wrong
the distance k1 from F_1 to P is not equal to the distance k2 from F_2 to P
but the equation of the ellipse is the points P where distance(F_1,P) + distance(F_2,P) = k1 + k2
 
but k1+k2 is for every p the smae
 
why do square brackets look so bad in latex, how can I improve them?
I mean
$$S_{[X]}$$
square brackets in subscripts
 
10:02 PM
Updated
2
Q: How to draw an ellipse if a center and 2 arbitrary points on it are given?

Karl's students How to draw an ellipse if a center and 2 arbitrary points on it are given?

 
@Karl'sstudents, what is a center?
 
intersection between major and minor
 
if you say the center it will be clearer
 
need 3 arbitrary points?
 
10:22 PM
$$||2||$$
what's the right way to make thos double bars?
 
$\|2\|$
@caveman \| a\|
 
@Karl'sstudents you are really 14?
 
@Charlie I will not reveal my privacy here as what Jasper Loy does. :D
 
why
 
10:30 PM
@Karl'sstudents haha okay
 
why is everyone so weird about privacy
 
@Karl'sstudents you speak japanese?
 
(removed)
 
@Karl'sstudents i didn't see the message....
 
karl's how old are you?
 
10:33 PM
(moved)
 
(ved)
 
@Ethan Oh my ghost.
 
()
 
10:34 PM
@κρανίοπεριπολία Won't you Choo choo me home?
 
My Father, if it is possible, may this question be taken from me.
 
what
 
(removed)
(emove)
(mov)
(o)
$\emptyset$
 
O my Father, if it be possible, let this question pass from me.
 
@Karl'sstudents ?
 
10:47 PM
@Charlie Yes. I am here!
 
@Karl'sstudents :D
 
11:07 PM
@κρανίοπεριπολία Bye, Skull
 
11:18 PM
Hi @jonas
 
11:34 PM
4 years later...
Are you hungry or angry?
 
11:59 PM
@Karl'sstudents :P
 
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