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12:10 AM
@TedShifrin Aw shucks...I figured. Just curious. Thanks though!
 
12:50 AM
Hello, I'm making a volumetric renderer. I'm trying to render the union of a rectangular plane and a square whose sides are equal to the maximum length of one side of the rectangle, but without using "if" in the GLSL shader code. Any ideas?
The rectangle and square are coplanar and the centers of both are aligned.
I'm also trying to calculate a vector using a sphere segment sitting on the square. The circular plane on the segment is coplanar with the square and the screen, and the width of the segment is equal to the width of the square.
 
Isa
1:27 AM
Complex Analysis: To transform the plane with slit [−1,1] into the upper half plane, I have the following: $T_1(z)=z-1,T_2(z)=1/z,T_3(z)= ? , T_4(z)=\sqrt(z),T_5(z)=iz $ thus $T=T_5\circ T_4\circ T_3\circ T_2\circ T_1$ is the desired transformation. My question is how should $T_3$ be defined?
 
 
5 hours later…
6:53 AM
[Random]
0.10010101=[1,4,6,8]
0.10110101=[1,3,4,6,8]
[a]+[a]=[a-1]
[a,a+1]+[a+1]=[a,a]=[a]+[a]=[a-1]
[a]+[b]=[a,b] if a<b
0.10010101+0.10110101=[1,4,6,8]+[1,3,4,6,8]=[1,1,3,4,4,6,6,8,8]=[2,3,3,5,7]=[2,2‌​,5,7]=[1,5,7]=0.1000101
But
0.10010101+0.10110101=1.01001010=[0,2,5,7]
hmm... careless mistake...
[1,4,6,8]+[1,3,4,6,8]=[1,1,3,4,4,6,6,8,8]=[0,3,3,5,7]=[0,2,5,7]
Cool, it works
And since I can do this from big to small, I can generate a sequence of sums of truncations that limits to $\pi + e$. If eventually periodic phenomenon is observed, then we are settled
For those who don't know what I am doing, here's a brief summary:
The above shorthands allows the computation of sums from the largest digit to the smallest digit by taking cared of carryovers in a commutative and associative manner. The basic idea is as follows:
1. Write the binary number you are interested in say 10010.01
2. Write the positions, denoted by the negative of the exponent, where it is one. i.e. $[-4,-1,2]$
3. Do the same for another binary number e.g. $111.01 \implies [-2,-1,0,2]$
4. Combine the contents of the two lists together $[-4,-1,2]+[-2,-1,0,2] = [-4,-2,-1,-1,0,2,2]$
5. Use the following axioms to simplify the resulting list
$[a,a]=[a-1]$
$[a]+[b]=[a,b], a < b$
Thus we have:
$[-4,-2,-1,-1,0,2,2] = [-4,-2,-2,0,1] = [-4,-3,0,1] \implies 11001.10$
I use negative of the exponent so that when I deal with $\pi + e$ I don't need to put minus signs everywhere which is annoying. If you want a more natural formulation, you can just write the positions as the exponents. Then you will use these rules instead:
$[a,a]=[a+1]$
$[a]+[b] = [b,a], a< b$
Now back to business
$\pi \implies$ [-1,0,3,6,11,12,13,14,15,16,18,19,21,23,25,29,33,38,40,41,43,47,48,53,57,58,60,6‌​3,64,6‌​8,71,72,76,77,80,81,85,87,91,93,94,95,103,104,106,107,108,114,115,116,119‌​,120,122‌​,126]
 
7:19 AM
@Sil Maybe you'd like this one as well: anvaka.github.io
@Sil Sorry! The URL was a bit wrong there. Here it is: anvaka.github.io/fieldplay
 
$e \implies$ [-1,1,3,4,6,7,8,9,10,11,16,18,20,24,26,27,31,33,37,39,41,42,43,45,46,48,51,53,55‌​,58,‌​59,61,63,65,67,68,69,70,71,72,74,75,76,80,82,84,85,89,97,100,101,102,105,10‌​6,107,‌​108,110,113,114,115,116,119,120,121,122,126]
Common digits places with value 1 between $\pi$ and $e$ in binary expansion:
[-1,3,6,11,16,18,33,41,43,48,53,58,63,68,71,72,76,80,85,106,107,108,114,115,116,‌​119,‌​120,122,126]*2
($*$2 means each element is actually duplicated. Alternately, think about adding two identical lists together)
Now to simplify it:
[-1,3,6,11,16,18,33,41,43,48,53,58,63,68,71,72,76,80,85,106,107,108,114,115,116,‌​‌​119,‌​120,122,126]*2 = [-2,2,5,10,15,17,32,40,42,47,52,57,62,67,70,71,75,79,84,105,106,107,113,114,115,‌​‌​118,‌​119,121,125]
So you see, the lists of common digits is that they all get shifted to the left by 1 unit
Now we can compare this with the digits in the $\pi, e$ that are not taken cared of, i.e.
$\pi$ remaining [0,12,13,14,15,19,21,23,25,29,38,40,47,57,60,64,77,81,87,91,93,94,95,103,104]
$e$ remaining [1,4,7,8,9,10,20,24,26,27,31,37,39,42,45,46,51,55‌​,59,61,65,67,69,70,74,75,82,8‌​4,89,97,100,101,102,105,​110,113,121]
Commons[-2,2,5,10,15,17,32,40,42,47,52,57,62,67,70,71,75,79,84,105,106,107,113,1‌​14,115,‌​‌​118,‌​119,121,125]
Common in both $e$ and Commons:
[10,42,67,70,75,84,105,113,121]*2
e remaining [1,4,7,8,9,20,24,26,27,31,37,39,45,46,51,55,59,61,65,69,74,82,89,97,100,101,102,‌​110]
Commons remaining:
[-2,2,5,15,17,32,40,47,52,57,62,71,79,106,107,1‌​14,115,‌​‌​118,‌​119,125]
Common in both $\pi$ and Commons remaining
[15,40,47,57]*2
Commons remaining:
[-2,2,5,17,32,52,62,71,79,106,107,1‌​14,115,‌​‌​118,‌​119,125]
$\pi$ remaining [0,12,13,14,19,21,23,25,29,38,60,64,77,81,87,91,93,94,95,103,104]
New commons:
[10,42,67,70,75,84,105,113,121]*2 = [9,41,66,69,74,83,104,112,120]
[15,40,47,57]*2 = [14,39,46,56]
Further increments after another series of commons are taken account of:
[9,41,66,69,74,83,104,112,120] => [8,41,66,68,73,83,103,112,120]
[14,39,46,56] => [13,38,45,56]
$\pi$ remaining [0,12,13,19,21,23,25,29,38,60,64,77,81,87,91,93,94,95,103]
$e$ remaining [1,4,7,8,20,24,26,27,31,37,45,51,55,59,61,65,82,89,97,100,101,102,‌​110]
Commons remaining [-2,2,5,17,32,52,62,71,79,106,107,1‌​14,115,‌​‌​118,‌​119,125]
And finally:
[6,41,66,68,73,83,103,112,120]
[11,37,44,56]
[0,19,21,23,25,29,60,64,77,81,87,91,93,94,95,103]
[1,4,20,24,26,27,31,51,55,59,61,65,82,89,97,100,101,102,‌​110]
[-2,2,5,17,32,52,62,71,79,106,107,1‌​14,115,‌​‌​118,‌​119,125]
There are no carryovers remained, thus the sum is done
Now, as you may have noticed, during this whole iteration, usually the carryovers in each step tend to be eaten up by $e$ instead of $\pi$
 
7:56 AM
How much do you have left?
 
This means, at least for this length, the probability that the digits of $e$ get shifted to the left by one is at least twice as high than those of $\pi$
In addition, the regions where there is a cluster of ones seemed to be uniformly spaced from each other, suggesting some kind of quasiperiodicity
It is unclear if as we make the binary expansion longer, it will tend towards periodicity
For comparision, here's the plot for the distributions of ones in $\pi$ and $e$
 
8:21 AM
$\pi$
$e$
$\pi +e$
All 3 of them. Note how there are digits that are never populated by $\pi,e\,\pi +e$ at least for this truncation
Also note how similar is the distribution of ones between $e$ and $\pi +e$, except with more periodicity. This suggests that while mostly what happens in the addition is that the ones in $e$ preferentially get shifted to the left, the occasional shifting of the digits of $\pi$ lead to more periodicity
In order to investigate further, we need some tools to quantify this change in the distribution, in order to figure out whether in the limit of countable places, $\pi+e$ will be eventually periodic
 
8:39 AM
Hmm maybe a plot of the carry overs will be more useful
 
 
1 hour later…
9:45 AM
@Cosinux looks like a lense
or lentil
 
10:00 AM
hmm...
We knew that $\pi$ is irrational, and there are many ways to write $\pi$ as an infinite series of rationals
What happens if we do a Fourier transform on pi to work out how many period 1, pipers 2, period 3 etc. components are there?
One suspicion is that the carryovers are actually blowing up some of these components, thus result in more periodicity
 
o..o'
 
@Secret Who are you writing with?
 
just sharing because Rambles got frozen due to inactivity
 
rip math chat
 
@Secret Please stop or go make a new room then. I am fairly certain nobody is reading any of that stuff, and it takes up a ton of space
14
 
10:10 AM
Hey. Can anyone explain it to me? It is claimed that every Einstein solution with cosmological constant in vacuum is locally isomorphic to Minkowski, deSitter, or adS?
 
The GR experts are in h bar
you should go there
 
10:36 AM
In other new Slereah returns
Given the desolation here. It is ripe to trigger another Berlin strike, $\pi$
but anyway...
 
I'm with @Tobias, @Secret.
 
Mornin
I went to bed; no idea what happened. Did I get an answer?
 
11:02 AM
Well then, I will see if I can get a mod to unfrozen my room cause pretty sure nobody want to have gazillion of rooms flooding the maths chat
 
no you didn't
 
In this que
https://math.stackexchange.com/questions/667998/show-that-ex-1-x-x2-2-cdots-xk-k-for-n-geq-0-x-0-by-in,
6005 says that $e^x > 1$ for $x > 0$; shouldn't that be $e^x = 1 + x$?
 
Leaky: Well if each Rambles get frozen due to inactivity and I had to make a new one, you can easily see how quickly those rooms will pile up. In fact, who's idea in SE to make chat rooms expire such that room owners cannot unlock them
 
@Tug'Tegin no
@Secret you can always ask mods to unfreeze them
 
I might see if ACM or other can help then, math chat mods are too inactive to find
 
11:13 AM
I think I'll ask my question another day.
 
In other news, I think this is where it started to go downhill, and I think this is the 3rd time I encounter this weird chemistry spike phenomenon:
yesterday, by Oskar Tegby
Is this what happens when drinking and doing math at the same time?
Still don't really understood how social chemistry works
> Once people think you are a lunatic, they stop getting interested and this is irreversible
 
Is it true that the image of a bounded variation path to a metric space is contained in a compact set in the metric topology?
 
hey, does someone here know how to use a class file in latex?
 
12:16 PM
What do you mean by "class a file"?
Haha! Woops! Sorry! I obviously misread that.
Here you go, @ShaVuklia

https://www.sharelatex.com/learn/Understanding_packages_and_class_files
I'm not entirely sure what your questions is.
Do you mean how to use \documentclass?
 
hey @OskarTegby!
yea so I got a class file
it's this:
\NeedsTeXFormat{LaTeX2e}
\ProvidesClass{uvamath}[2017/10/27 0.4 Bachelor Wiskunde LaTeX document class]
\LoadClassWithOptions{scrreprt}
\RequirePackage{graphicx}
\DeclareOption{english}{
% English values for translatable constant text
\def\supervisortextsingular{Supervisor}
\def\supervisortextplural{Supervisors}
\def\titletext{Title}
\def\authortextsingular{Authors}
\def\authortextplural{Authors}
\def\datetext{End date}
\def\secondgradertextsingular{Second grader}
\def\secondgradertextplural{Second grader}
and my file has to look a certain way, but I'm not sure how to get this
for instance, "project report mathematics year 2" should be right above supervisor
but I'm not sure how to get that
 
m.imgur.com/2vaVs3x Can somebody give me a hand with this?
I’m unsure as to what would be in vector d for one
But also unsure as to how it would solve for x?
 
@ShaVuklia Maybe this could help. :) I just Googled it. I don't know myself. There's a forum for LaTeX that also has a chat. You should search or ask there!

https://tex.stackexchange.com

https://www.tug.org/twg/mactex/tutorials/ltxprimer-1.0.pdf
 
thanks!
 
12:30 PM
surely it does not just stop at 5 sides I think
 
 
2 hours later…
2:02 PM
If $V$ is a vector space, does any norm on $V$ make it a locally convex topological vector space?
 
Do you mean any as in that there exists one such norm or as in that every norm that exists is such a norm?
If it is the latter, then it can't be true as every normed vector space would be a convex topological vector space.
 
I mean every norm on $V$.
 
That's just my intuition without knowing anything about topological vector spaces.
 
Yeah, that's basically what I am asking about: is every normed vector space a locally convex topological vector space.
 
If it's the case, then why bother with the definition of a convex topological vector space?
 
2:08 PM
Probably because there are non-normable topologies which make $V$ into a locally convex TVS.
 
However, I don't know about the details. I think that @TedShifrin might do.
Okay.
 
In fact, the finest locally convex topology is defined by all semi-norms, so there probably isn't one single norm which generates it.
Okay. I think the answer is yes, because the vector space operations are continuous wrt to the norm and the open discs defined by the norm are convex.
 
2:31 PM
@geocalc33 Hey! How are you doing?
 
2:41 PM
@MatsGranvik, I think I might be able to interest you in the last question I wrote... based on some previous questions I have seen you answer/engage with.
 
3:00 PM
math is cool
 
@Mason Looks a bit like Dirichlet series for logarithms. I know that such series converge if the sum of the period is zero but I don't know exactly why.
 
I can prove that they diverge if the sum is not zero.
for s=1 anyway.
@MatsGranvik. I just thought it well aligned with your interests.
 
@Mason Jaume Oliver Lafont in the OEIS has made the same discovery before me. And Akiva Weinberger has also asked about them here on the forum.
 
Yes. Those names look familiar to me. i707 also would be a good person to have take a look.
 
3:50 PM
@MatsGranvik. Ok. I tried to make the problem a little more exciting
Maybe some specific values will bring the problem to life for some people.
Do you know if I am using the proper symbol for the Algebraic multiples of a constant c
just A[c] no?
 
@Mason Looks like you are doing Hurwitz zeta functions or almost the same the generalized Riemann zeta function, according to the Wolfram Alpha output.
 
Yeah. We should be able to write this as rational linear combinations the the generalized zeta function.
 
@Mason What is the union or intersection that you are asking about?
 
hmm? That's the whole question?
 
Yes that is the part I don't understand.
 
3:58 PM
That's not good.
Ok. Let me try.
The values you can create with a periodic sequence and some fixed s. Say we have s=7.
How many different numbers can we make?
Countably many.
How come? Because there are countably many periodic sequences.
And each sequence gets you a value.
Now fix s to some other value.
say s=13.
The numbers you can create with s=7 and the numbers you can create when s=13. What is the overlap?
 
good question
 
I thought so too!
Very little excitement for what I think must be an essential question about the real numbers.
Should I change anything about my question? I added some numbers to make it more relateable.
 
For complex numbers $s$ you will have intersections.
 
!!! Really/
 
Yes but you will not be able to say what they (the complex numbers $s$) are with algebra.
Or I think so. I have not checked.
 
4:09 PM
Well. My real focus was to alert you to a problem that I thought you might enjoy. (and get feedback on the question).
 
Heyyo guys! :-)
 
If we are going to chat about the question itself it should be somewhere that future readers can find it.
@lush. Hello.
@MatsGranvik. If you are correct about this (and I suspect you must be at least in some trivial ways: consider $s=1+i$ and $s=1-i$... these must relate to one another.) It should be a comment on the page itself so other readers can see it.
 
Hi @all!
@Mason I think I did not get the question completely
 
Thanks.
Let me work on it. I appreciate the feedback.
@Rudi_Birnbaum. I was going after Mats because I know they have interest in reimann zeta functions.
The last question that I posted on here on MSE is what we were talking about
And I just gave a specific example above.
 
Just to comment on your question further.

This is how you raise a number to a complex power s=b+I*c

1/a^(b + I*c) = 1/a^b*(Cos[c*Log[1/a]] + I*Sin[c*Log[1/a]])

This is an equation Mathetmatica can solve:
Reduce[Cos[x*Log[2]] == Cos[x*Log[3]], x]

Solving this equation would be a mathematical breakthrough:

Reduce[Cos[x*Log[2]] == Cos[x*Log[3]] + Cos[x*Log[5]], x]

So much for the hope of algebra to find those intersections. What you can do is replace the logarithms with rational numbers but it will not get you anywhere before you understand this picture:
 
4:21 PM
 
user131753
Let $X\ne \emptyset$ and $Cl_1$ and $Cl_2$ be two topological closure operators on $X$. If both of them induces same topology on $X$, are they equal?
 
user131753
I don't think they are. However I am lacking a specific counterexample.
 
5:17 PM
@Mason OK, thanks for the info!
 
@user170039 I think they are equal, take $A \subseteq X$. Then $Cl_1(A)$ and $Cl_2(A)$ both represent the closure of $A$ in the topology on $X$ (since they induce the same topology) so $Cl_1(A) = Cl_2(A)$. This applies for every $A \in P(X)$ so $Cl_1 = Cl_2$.
 
5:35 PM
@user170039 yes, because you can recover the closure operator from the topology
 
5:51 PM
Is max monotone? i.e. for $a<c$,$b<d$ then $\max\{a,b\}<\max\{c,d\}$?
It is true isn't it?
 
6:32 PM
o..o
 
7:12 PM
It has to be true geometrically, but I have no idea how to prove this algebraically
since no matter where I put my b,d pair wrt a,c, I get the same outcome
 
7:44 PM
@OskarTegby hey! Doing alright, been very busy. How are you?
 
I mean, the boring proof by casework would seem to suffice
Tedious but straightforward
Hmm, is the following true: if a<b, then max(a,c)<=max(b,c) ?
It’s not a strict inequality since one could have a<b<c
 
8:18 PM
@Nick yes math is pretty cool :)
 
 
1 hour later…
9:19 PM
Pleased to announce that math formatting is now enabled on SE:AI Feel free to come take a look and see if any open questions are of interest!
 
9:47 PM
@geocalc I'm fine. School's starting soon. Looking forward to meet everyone again. What have you been busy with?
 
When you have a commutative local ring with a nilpotent maximal ideal, is it necessarily complete w.r.t. the ideal?
I have no feeling for these things.
 
@rschwieb yes
 
@MatheinBoulomenos Hi!
@MatheinBoulomenos Actually, I sent you an email recently with some diagrams... did it get caught in spam-filter hell?
 
10:02 PM
@rschwieb Hi
no, I got it, but I didn't have time to look at it in detail.
 
@MatheinBoulomenos ok :) that's understandable
 
@quallenjäger: By symmetry you can assume $\max(a,c)=a$. Then $a<b\le\max(b,d)$. Done.
 
and if I have $f(x)<g(x)$ and $h(x)<b(x)$, do I have $max(f(x),h(x))<max(g(x),b(x))$?
 
Why is that a different question?
 
because it is a function with infinite many point.
previously we have only finite sets.
 
10:12 PM
You put $(x)$ there ... so it's about individual values.
 
Ah ok I see.
Sorry I am really weak in so basics.
 
Do you mean to take the maximum of all values of $f$ and all values of $h$?
That maximum might not exist, for starters.
 
No, I don't I compare them pointwise
 
Now I don't understand.
 
I mean I don't, I compare them pointwise.
 
10:14 PM
Oh, then it's exactly what we did already.
 
Yes, thanks
Lol I started with theoretical physics.
I never have been taught rigorous analysis and this kind of stuff.
All I have been taught is what I can do and I never understand why.
It's now some kind such a pain to track down basics.
d
 
For some things my YouTube lectures might help you. For basic proofs/reasoning, I'm fond of a book by a British guy named Kevin Houston. It's called How to Think Like a Mathematician.
2
 
Thanks! I will check them out.
 
heya @MikeM
 
10:30 PM
hi @Ted
 
heya @Mathein
 
Hi @Ted
 
I'm super-dumb tonight so can someone help me with this simple problem: |z| = 1 and |z^3 + i| = 1 (z is complex)
 
|z^3| is also 1 - use that and draw a picture
 
I thought taking powers of numbers on the unit circle meant rotating them, so I can't really figure out how +i would ever result on something still on the unit circle
 
10:43 PM
I was about to say the same thing.
Think about intersecting the circles $|z|=1$ and $|z+i|=1$. (Really it's $z^3$ in the second one, but we'll get to that in a moment.)
 
right ok I get the intersecting circles thing
 
So, look at the point in the 4th quadrant.
 
mhm
 
For what $z$ does $z^3$ give you that point?
 
@OskarTegby moving, and trying to understand complex-to-simple state transitions and vice versa, via Hamiltonian concavity-convexity mappings
 
10:47 PM
@TedShifrin I'm not sure, the one whose phi is 1/3 of z's?
 
@jcora: That's one, yes. In fact, there will be three different points :)
 
wait why three?
 
Find me three $z$ on the unit circle that satisfy $z^3=1$.
 
;_; I would say that holds of any point on the unit circle
 
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