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00:02
@nerdy Maybe this helps?
i should have said differentials haha i dont wnna go to hyperreal numbers
I saw this from wikipedia "The precise meaning of the variables dy and dx depends on the context of the application and the required level of mathematical rigor."
@nerdy What is it you want to know?
Where i can find that mathematical rigor about dy and dx ?
i want to understand them
know what they represent ( are they a function,. are they a number ? ) ?
are they a variable
what does dx mean ?
etc
It is not usually a "stand alone" symbol.
That is, you cannot isolate it from say $$\int_a^b f(x) dx$$ or $$\frac{dy}{dx}$$
That is simply notation.
but we often do
f(x) = x²
y = f(x)
dy = f '(x) dx
in that case, dy = 2x dx
00:07
@nerdy It is rather an informal but useful manipulation.
hm, is it ?
didnt know
I think of it as meaning "an infinitesimally small change in the function, smaller than any number you can think of, but not zero."
@PeterTamaroff voted as spam.
Still have no closing powers.
And it's gone.
@PeterTamaroff Have you voted to close the sister question?
01:16
@BenjaLim Didn't see that one.
@PeterTamaroff Common the one about my sister refuses to learn math
A friend of mine just told me that his teacher wrote $$\frac{a*\infty}{b*\infty}$$.
Now there's this post to close Just look at the OP's track record!
@amWhy I prefer to ignore those.
It's the track record that troubles me. It hardly seems like a sincere question.
@PeterTamaroff I typically do to...
02:04
Anyone know if there's a table of Mellin transforms online somewhere?
besides wikipedia / mathworld / planetmath?
(assuming one of them has one)
@amWhy seems sincere to me. and also revealing of a nonsensical understanding of math concepts.
but it's not very extensive.
@anon I guess you're right...I suspect you can glean (by now) that I am fairly permissive about content on the site, questions etc ... So it's not usually like me to write off a question. I think I've been a little soured today...or I'm tired, or both. I stand by my downvote, but would have rather not voted to close.
dude needs to sit down and relearn intro analysis and elementary set theory, properly
@anon amen...fully agreed!
02:19
does anyone here can help me with a probability problem??
21 hours ago, by anon
just ask, don't ask to ask
:-)
we have 6 machines the lifetime of each ~ exp(-ln(.7)=0.35) if one machine fail it is reapair the next day .What is the probability that some particular day NO machine work?? ./So far I got : If the lifetime is grater than the perticular day the probability = 0 I also think to separate the even days of the not even /
Is this the right path ??
02:41
So who actually reviews the flagged comments?
Moderators?
10K+ users?
Or is it some feature I don't know about?
both
only moderators can act unilaterally on them I think
others (don't remember the exact rep threshold) just vote on whether they're reasonable or not, essentially
03:41
Exciting news from meta.SO: kinder, gentler closing process. Coming soon to a StackExchange site near you.
2
@user79365 Thanks for the news! Has this also been posted to meta.math.se?
04:04
Hi @amWhy how are you?
@skullpatrol Hello! Okay...thinking about bedtime... How 'bout you?
@amWhy Fine thanks :-)
04:16
How 'bout a boat?
@Ethan [One reason why you shouldn't remove your messages(yumceleb.com/pics/2013/01/i-see-what-you-did-there-261.jpg)
@amWhy I considered this, but I don't vote to close (<3K), so I'm not the right user to open meta discussion on this topic.
05:02
Yo @Παρθ Κοχλι wazzup?
@skullpatrol Hi, I'm doing good
 
1 hour later…
06:09
(-:
Hi @JayeshBadwaik how are you?
@skullpatrol Hi, I am good. What about you?
@JayeshBadwaik Fine thanks.
Also, I saw your message about "Do you want a piece of me?" I did not understand it (do not know about Britney Spears or rather her songs much).
@JayeshBadwaik It was just a joke :D
06:13
She is basically a bad joke of the western part of the word...
...sort of like Gangnum style is to the east.
Gangnam Style is not a joke (atleast to me), its a parody alright. But the song itself is not a joke.
A LOT of people agree with you!!!
"As of June 7, 2013, the music video has been viewed over 1.639 billion times on YouTube, and it is the site's most watched video after surpassing Justin Bieber's single "Baby.""
can someone help me evaluate $$\lim_{s\to 1} \frac{d}{ds}(\zeta(s,q)-\frac{1}{s-1}) $$ in terms of a special function where $\zeta(s,q)$ is the hurrwitz zeta function
Morning ^_^
@Ethan Still the same question ? :)
@JayeshBadwaik Can you help me with a Levy Curve ?
06:29
no thx
lol joking
what do you need help with?
I dont know asking this question in math SE is appropriate or not thats y i am writing this question here. I want to know whether limit obeys distributive law
I need to make a program to make it but I am kinda confused about the logic
@Ethan Tell me when you opoen the page
06:31
@t3st can you be more specific
Yes it does
@t3st
@ethan for example $\lim_{x\rightarrow a}f(x)-f(x)g(x)$ can be written as this $f(x)(\lim_{x\rightarrow a}1-gx)$
@LittleChild that is kind of vague
If both $\lim_{x\to a}f(x)$ exist, and $\lim_{x\to a} 1-g(x)$ exist
$\lim_{x\to3}[f(x) + g(x)]$ = $\lim_{x\to3}f(x) + \lim_{x\to3}g(x)$
Yes, assuming both the limits exist
Take $f(x)=sin(x)^2$, $g(x)=cos(x)^2$
06:33
k so its possible if limit exist
Yes. In highschool calculus they will give you problems where limit will exist :)
$1=\lim_{x\to\infty}sin^2(x)+cos^2(x)\ne \lim_{x\to\infty} sin(x)^2+ \lim_{x\to\infty} cos(x)^2$
So.. anyone going to help me with Levy Curve ?
i still don't understand what you need help with
YOu did not open the page
How can I continue further ? :)
06:35
i did open it
Ok, have a look at the diagram
thanks liitlechild and ethan
we start with a single line and make an isoceles triangle out of it
We now use the two sides of the triangle to repeat the same process.
so we have two lines, two triangles
but then after third iteration, this pattern breaks
@Ethan We get 6 lines, 8 triangles
sorry nvm, I don't want to help
06:38
lol
You can clearly see now. Black lines are original lines.
Blues are the ones we construct
Hello. First time using the chat boards on this site.
yes it looks boring
Found the relationship
triangles to draw = number of lines + (number of lines)/3
06:41
@DanielMargolis Welcome :-)
Hi @Lord_Farin how are you?
@skullpatrol Fine, I guess.
Is there a transcendental number which does not have a trigonometric explanation? As all rationals and non-transcendental irrationals have an algebraic explanation?
what do you mean by explanation
It can be termed using algebraic numbers and trigonometric functions.
termed?
what do you mean
by that
06:46
@DanielMargolis Using at most countably many operations, we can still only write down countably many expressions, so at most countably many real numbers can be of the form you describe. The rest is just... let us say, intangible.
Yes. It means using a cosine function, a hyperbolic sine function, or a inverse tangent function, you can form this value by plugging in any algebraic function.
Is cos(1) intangible?
@DanielMargolis Well, no. My comment was more to the extent that if you take, say $\{\sin,\cos,\exp,\log,+,\times,\ldots\}$ (at most countably many operations), and apply them to the algebraic numbers (of which there are countably many), then you can still only express countably many real numbers.
Naturally, $\cos(1)$ is one of them.
Therefore the infinitesimals are included in $R$?
Now, the current tools in number theory aren't very good at helping us determine if e.g. $\pi^e$ is tangible over the six operations I wrote above, but we know that there must be a large reservoir of inexpressible reals.
Until a new operation, math, and way of thinking is made to make up for that.
06:55
@DanielMargolis No. To say that there are intangible numbers between any two tangible numbers is wholly different from the existence of a number $x$ that has $0< x< \frac1n$ for all natural $n$.
(The quantifiers are interchanged.)
@DanielMargolis Indeed. And that's how mathematics has often progressed throughout the centuries. Many large research fields arose when trying to solve a certain open problem.
:-)
I must get back to my topology if I ever want to be a professor.
@DanielMargolis Ok. I hope to have answered your questions regarding intangible/transcendental numbers.
I am still intensely interested in the existence of uniquely significant values in R / Q. May the search continue!
Also. e and \pi are trigonometric transcendentals. Therefore, so is e^pi and pi^e.
07:17
Presumably by "tangible" Farin means "definable."
and presumably "trigonometric transcendentals" in this context are those numbers that cannot be expressed as a basic trig function evaluated at an argument in a certain set (e.g. rationals or rational multiples of pi)
Define arccos(x)=pi. I'm not entirely certain of how to obtain an isolated e without using imaginary numbers or hyperbolic f(x)
dunno what x=-1 has to do with anything
you will not obtain e using only sin, cos, tan, cot, sec, csc, pi, and rationals.
the imaginary unit i or equivalently hyperbolic functions would be required
You can using hyperbolic sin and hyperbolic cosine now that I think about it.
yes
Cosh(x)+sinh(x) = e^x
07:29
well, cosh(x)+i*sinh(x)=e^x
Is that trigonometric?
err, scratch that
cosh and sinh are hyperbolic trig functions
Haha I think it's the collapse of cos(x) + isin(x) onto reals, but this requires linear algebra, complex variables of root 2, and logic functions of graphs.
Like the absolute value only for given i's
if you replace x with -ix in the expression e^ix = cos(x)+i sin(x), you get e^x=cosh(x)+sinh(x). no linear algebra, complex numbers are involved yes, but complex variables of root 2 and logic functions of graphs are very strangely constructed phrases.
What is the 4th root of -1?
07:41
there is more then one
why is there more then one
?
@DanielMargolis $e^{i\pi}=(-1)$
?
(-1)^(1/4)
07:46
$(e^{i\pi/4})^4=e^{i\pi}=-1$
$(e^{i\pi 3/4})^4=e^{i\pi 3}=e^{i\pi}=-1$
there are n distinct nth roots of unity in the complex plane. as corollary, there are n distinct nth roots of any nonzero complex number. for instance, there are two different square roots of 1: namely, 1 and -1.
This doesn't make sense
what doesn't make sense
with choices of things called "branch cuts" in the complex plane, one can construct "nth root functions," i.e. a function such that f(x)^n=x for all x. of course f() can only ever take on the value of one of the nth roots of a number, not all of them.
(sqrt2/2+isqrt2/2)^4 = -1
07:51
yes
if you write z=(1+i)/sqrt(2), the fourth roots of -1 are {z,iz,-z,-iz}
ok, this seems to prove there are only one forth root of -1.
I gave you four different values, namely {z,iz,-z,-iz}, all of which when taken to the fourth power equal -1, i.e. four different fourth roots of -1. how does showing four things prove there is only one thing?
So I shouldn't assume (-1)^3 is -1
when you say things like that it makes me wonder if your account is simply a practical joke
(-1)^3=-1 is true, why wouldn't it be?
Meant 1/3
08:00
le sigh
generally you can define nth root functions for all real numbers if n is an odd whole number, or nonnegative reals if n is an even whole number, without any issues.
(-1)^1/3 is not -1?
1 min ago, by anon
generally you can define nth root functions for all real numbers if n is an odd whole number, or nonnegative reals if n is an even whole number, without any issues.
n=3 is odd; you can define a third root function on all real numbers, -1 is a real number. in the context of real numbers you can say (-1)^1/3=-1. however in the complex plane one needs to make choices in how one constructs a 3rd root function, and in the process (-1)^1/3 may or may not be -1 depending on those choices.
(1+isqrt3)/2 = z
So one would need to construct rationals with w/v =/= nw/nv
Far simpler to count them this way.
08:23
hello
@anon
08:44
Oh I've been trifling with the Beal conjecture and found some interesting results when you set A B and C equal. A must be divisible by 2.
 
6 hours later…
14:17
it is really quiet here
 
1 hour later…
15:27
@DominicMichaelis so?
16:10
HI
anyone here?
w1[ a1;b1;c1] + w2[a2;b2;c2]
hi
Derivative of a vector with Respect to scalar
f=w1[ a1;b1;c1] + w2[a2;b2;c2],what is the partial f partial w1?
Have anyone see such thing before?
hello
16:16
hi
please i need help
loool
16:55
someone WHO KNOWS probability ?? math.stackexchange.com/questions/418964/…
17:15
Solve $ax-a^2=bx-b^2$ for $x$.
ax-bx=(a-b)x=a^2-b^2 -->x= a^2-b^2/(a-b)
Simplify please.
x=a+b
You are missing something in your answer...
$x=a+b$ is correct.
(a-b) can not be 0
17:22
Yes.
$a\neq b$
Do you know something about probability ??
or know someone who does??
guys, is a subspace simply a lower dimensional version of a space?
is a subset of the space with certain proporties
the subspace can sometimes not look like the space so i wouldnt call it a lower dimensional version
18:27
hi
@MaisamHedyelloo ?
 
1 hour later…
19:33
@Gmath If you ask in the main and then spam it in the chat, people will refuse to answer.
The question in the main already has exposition.
if I want to solve the Integral $\int_{-\infty}^\infty e^{-\alpha x^2-i\omega x} dx$, how do I do that? I am guessing Residue theorem
however, I dont know around which point
Greetings
Here is lovely series I'm thinking of right now: if $b(k)$ is the number of zeros in base $7$ representation of $k$, then I want to find for which $x$ the series converges
$$\sum_{k=1}^{\infty} \frac{x^{b(k)}}{k^7}$$
19:58
Greetings :D
@skullpatrol hello! How are you? :D
@Chris'swisesister Fine thank you, how are you?
@skullpatrol playing around with some cute calculus questions.
@BandeiraGustavo How do I spam!!?? I answer some doubts
20:18
Hello people.
Hello.
@Lord_Farin Great Farin! Hello! How is it going there? :-)
@Chris'swisesister Good and bad. I'm displaying more and more discipline, but I discover that there is more still to do than I thought.
20:25
hi
@JulianKuelshammer Hello Julian, valued fellow crusader. :)
@Lord_Farin interesting.
@Lord_Farin we are making progress, but not as fast as one would hope for
@JulianKuelshammer It would be great to have our team expanded by another two or three.
But in principle it's already an achievement that we are gaining; it means that we are answering more questions than there are asked per day.
20:39
These "revival" badges keep flowing in...
@Lord_Farin have you seen the series I posted above?
@Chris'swisesister I have now.
@Lord_Farin it seems so lovely to me. I think I make up an wallpaper with it and set it on my desktop background.
@Chris'swisesister It's radius of convergence is $1$. Calculating it for a given $x$ will be a pain.
I'm glad you encounter things you consider beautiful in mathematics. To me, such hints at where you should try to focus on, since more often than not, joy will team up with skill and ability.
@Lord_Farin math is full of beauty.
20:46
and vice versa
@Chris'swisesister I know. But while I primarily find it in logic, your most plentiful source is analysis.
@Lord_Farin that's right.
20:58
Does anyone know how to show that $Res. \frac{zeta(s)}{s-1} = \gamma$?
er
$Res. \frac{\zeta(s)}{s - 1} = \gamma$
$\zeta(s)/(s-1)$ has no poles. the residue of $\zeta(s)$ at the pole $s=1$ is simply $1$. you are probably thinking of $\lim\limits_{s\to1}\left[\zeta(s)-\frac{1}{s-1}\right]=\gamma$
ah, I'm thinking of $(s-1)\zeta(s)$, derpola cola
HERPA DERPA :)
Hm, this proof turned out a bit longer than I expected when I started it...
21:15
@anon I'm guessing the residue can be shown by dividing the Laurent series for the zeta function en.wikipedia.org/wiki/Riemann_zeta_function#Laurent_series by s-1.
what I am also wondering about is this wolfram alpha result: wolframalpha.com/input/…
that doesn't seem right.
21:36
it should have residues of $\frac{1}{2}, \frac{-1}{12}, and \frac{-1}{2}$ if I've done my math correctly
22:14
@Lord_Farin TL;DR?
+1 on faith.
@PeterTamaroff Be sure to at least read the part that is not natural deduction. :)
22:50
@skull ;-)
@amWhy :D
@skullpatrol Does what I wrote make sense?
@amWhy Yes.
@skullpatrol good!
@Bitrex Perhaps you mean that $\lim\limits_{s\to1}\zeta(s)(s-1)=1$
@Bitrex This is a much simpler result:math.stackexchange.com/a/412668/13854
22:56
no, see the W|A link given
@Lord_Farin Any idea if ZF is sufficient to prove that any compact connected Hausdorff space with at least two points is uncountable? I've been asking around and searching around and coming up empty.
@anon Yeah, I just noticed. I prove that somewhere too
0
A: How to show that the Laurent series of the Riemann Zeta function has $\gamma$ as its constant term?

robjohnIn this article, I show that $$ \zeta(s)=\frac1{1 - 2^{1-s}}\sum_{n=1}^\infty\frac{(-1)^{n-1}}{n^s}\tag{1} $$ converges for $\mathrm{Re}(s)>0$ by applying the Generalized Dirichlet Test. To apply the test, we need to show that the partial sum of $(-1)^{n-1}$ is bounded, $|n^{-s}|\to0$, and $$ \s...

0 votes for that answer :-)
@robjohn Thanks!
Now I have two votes for that answer, but I've already capped :-( I should have waited an hour to mention that answer :-)
23:13
I'm hoping to break 1000 sometime this year :D
It probably won't be via answers, so I will have to think of good questions.
23:47
$$(x+y)^n=\sum_{j=0}^n\binom{n}{j}x^{n-j}y^j$$
In a summation such as this one, j is always equal zero?
@BandeiraGustavo no. $j$ takes on any value from $0$ to $n$
I think he meant does $j$ always start at zero.
@robjohn Then n is always equal to n? I'll just have to "move" j, right?
@BandeiraGustavo Yes. $j$ will iterate through all integers from $0$ to $n$
Sorry, I have to go pick up some things for my wife. bbl
@robjohn Ok. Thanks.

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