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12:04 AM
that seems like a really good option. i only recently (last month or so) bit the bullet and purchased a mathematica license. i still am getting used to it but the way it handles functions is nicer than anything else ive worked with.
 
12:24 AM
Very powerful!
 
 
2 hours later…
2:31 AM
I'm sorry to bother this chat with simple and trivial questions but why is it that the polynomials of degree $\leq 2$ form a set of representatives for $\mathbb{Z}_3[X]/(X^3+1)$?
 
from the division algorithm, any polynomial in Z_3[x] is a polynomial multiple of (x^3 + 1) plus a 'remainder' that's degree at most 2
 
Oh, because to find an element of that finite field I would have to get a polynomial, divide it by $X^3+1$ and get the remainder
Yes!!! Ok!!
Sorry!
 
no apology necessary
 
@NoName @TedShifrin, like this?
 
d/dx g(f(x)) = g'(f(x)) * ___
 
2:45 AM
Yeah, so the derivative of ln is 1/x
And f(x) becomes f'x
 
i'm with you on the 1/f(x) bit
but ___
 
Ok ok
Thanks leslie,i screwed up chaining
 
your imagine reminds me of something weird i noticed when i was unpacking from the last move and saw some stuff i had written 25 years ago
in my handwriting, the bar of my lowercase f used to go straight through the stem of the f
 
@leslietownes d/dx g(f(x)) = g'(f(x)) * g(f'(x))
 
but now when i write it, it stops at the stem (like yours above)
 
2:49 AM
Hehe,i like the later f better than a straight through,
My problem is i dunno what f' is
Oh but i do have a differential equation
 
___ should be f'(x), not g(f'(x))
 
Ohhhh... oui!
Oops
Thankyou!
 
3:08 AM
Saved me the exclamation!
 
3:52 AM
@TedShifrin how to get linear combination?
 
You have to use the areas as coefficients and prove you get $0$.
 
Hi @TedShifrin
 
Hi, koro
 
I asked for hint yesterday
on how to prove that a group with no proper subgroup is of prime order p
I managed to prove it and I have written my proof on the aforementioned link that is here: math.stackexchange.com/questions/4134590/…
I request your review sir @TedShifrin
 
Idea looks right, but don't use $p$ and $q$ when they're not necessarily prime.
 
3:56 AM
Noted :)
Rest all is correct I think :)
 
Yes, idea is fine now!
 
Thanks a lot sir @TedShifrin :)
 
Sure :)
 
EM4
4:25 AM
@TedShifrin
 
Hi, @EM4
 
EM4
how are you?
 
Still kicking, and you?
 
EM4
trying to survive got finals back to back to back next week.
 
In math one should be prepared all along the way, not cramming for finals.
5
 
4:34 AM
H
 
EM4
yes
did you seen my email I send.
 
Yes, I saw it.
@Euler2 K
 
4:53 AM
Hello Does someone know why an MSE could have the value of 2 thousand?
I came across a paper, and among their results there was MSE=2227.416
That looks very strange
I've never seen that kind of values.. MSE is usually decimals
 
5:26 AM
What could MSE possibly be?
 
if the numbers were super big and varying i guess i wouldn't be too surprised by that
 
mean square error I think
 
i mean, sometimes it's small just because people choose units where things don't numerically vary too much
 
however, i would consider 2227.416 to be a decimal?
 
oh haha i didn't even notice
i took it to mean "number less than 1"
fair point, it's not MMCCXXVII.416, is it
 
5:42 AM
Mental Stability Examination
lol
my iq is 314
var iq = 314;
 
5:57 AM
@copper.hat Mean Square Error
 
it could be any non negative number, it really depends on what you are observing.
 
@copper.hat ahh, I had this silly idea that it was among, say, .9 to .000...
 
it is just one way of quantifying error, there are many.
 
6:29 AM
@copper.hat Yes, yes, I somehow didn't saw that. ugh..
well, thank you for your assistance
Thanks leslie too
 
 
2 hours later…
8:26 AM
a nice name for this function?
 
@TedShifrin: It seems that case (2) here has problems math.stackexchange.com/questions/4134590/…
 
 
1 hour later…
9:45 AM
Guys , pls check your answer for this Q.
If the range of this function $f(x)$=$\frac{x-A}{x^2-5x+6}$ = R. Then, solve for A .
Textbook says 2,3
I think that is wrong.
 
 
2 hours later…
12:11 PM
WTH does this even mean "If we start at c and nudge x a little to the right, f(x) changes by f’(c) times the amount we changed x. If this factor is positive, then f(x) changed by a positive amount, so ff is increasing near c."?
wth is nudge?
I assume it's epsilon then it makes sense
 
12:55 PM
Maybe this is a silly question but for two real functions $f$ and $g$, does $f\leq g$ always just mean a pointwise comparison of $f(x)$ and $g(x)$ for all $x$ in the domain?
 
1:23 PM
I have seen it used for that. But yes a bit ambiguous
If I defined a geodesic between two densities via the wasserstein metric will the result also be a density ? ( i.e will it be absolutely continuous to the lebesgue measure
 
 
1 hour later…
2:32 PM
dw solved it
 
2:55 PM
@user863565 in this instance, change a slight bit
 
3:16 PM
@TedShifrin can you give out yesterday's question?
Find the value of $\lambda$ so that the points p q r s on the sides OA, OB ,OC and QB respectively of a regular tetrahedron OABC are coplanar. It is given that $\frac{OP}{OA}=\frac{1}{3}, \frac{OQ}{OB}=\frac{1}{2},\frac{OR}{OC}=\frac{1}{3} $ and $\frac{OS}{AB}=\lambda$
 
3:30 PM
@SrijanM.T if A is not 2 or 3, then as x approaches 2(or 3), the function will approach $\infty$. So A must be 2 (or 3), in which case the limit as x approaches 2(or 3) becomes -1 (or 1). I.e finite.
 
3:43 PM
@Rover Here's the general result you should try to prove (using determinants or cross products). If $A,B,C$ are the vertices of a triangle and $X$ is a point in the plane, you can write $X=\lambda A + \mu B + \nu C$ for unique scalars $\lambda,\mu,\nu$ with $\lambda + \mu + \nu = 1$. And the geometric interpretation is that, for example, $\nu$ is the ratio of the (signed) area of $\triangle $ABX$ to the area of $\triangle ABC$.
 
@TedShifrin does anything obvious stand out to you as a solution for this PDE? $\partial_t \rho = -v \cdot \nabla_x \rho + \nabla_v \cdot ((\gamma v + \nabla U(x)) \rho - \frac{k_B T}{\gamma} \nabla_v \rho)$
if we had $-v \cdot \nabla_x \rho = 0$, then the solution is $C e^{-U(x) / k_B T}$
the solution is probably not far off from that
 
Hell no, @JoeShmo.
 
:-) prof's a great guy, but it's his first time teaching this course (I think?) and the book is brand new, too. I hate being a lab rat
 
4:07 PM
Hi @TedShifrin
There was a mistake in the proof we discussed earlier
I have fixed those and posted an answer/fix here math.stackexchange.com/a/4135318/266435
I request your review on this also.
 
Is the function $x^x^x^x...$ has a name?
 
To summarize the problem in earlier proof: $G$ was asserted to be finite but that was to be proven. That's one. Another issue was in my case (2).
 
4:35 PM
@satan29 I was checking up Q on this site and I saw someone Q which I liked. I’ll share it
That guy had answer as -6
0
Q: Find this Question value using range method.

RiderIf the range of this function $f(x)$=$\frac{x-A}{x^2-5x+6}$ = R. Then, solve for A . How can I solve this question.

So , the person who answered it gave the Ans as -6
 
@SrijanM.T: A can't be 2 or 3.
Reason is that if $A=2$, then you get $\frac1{x-3 }$ and its range is not $\mathbb R$. Range is actually, $\mathbb R-\{0,-1\ }$
 
@Koro Ok, then why does satan29 say that it must be 2 or 3 ?
 
I have added some more clarification in my comment.
Can you fill in the gaps?
 
5:17 PM
@JoeShmo stop complaining and have some more cheese.
@TedShifrin is that the mantra of the day?
 
Maybe of the year!
 
It flows even better than "Hell, no! We won't go!"
 
@Koro: I am tired of this question. Please stop pinging me about it.
We're showing our age, @robjohn.
 
Why aren't Mike, Balarka, Thor, Italy man showing up these days?
 
Mike disappeared quite a while ago. Balarka and Thor and Alessandro have been around (although Balarka took a break).
 
5:22 PM
Oh right. Thor seems to be active.
 
@TedShifrin Dec 6, 1967 is apparently when that chant was started.
 
Actually, its me who is irregular.
 
Yup, Vietnam.
 
@feynhat fiber
 
@robjohn's "humor" seems to have taken a hit with his increased age.
 
5:24 PM
@TedShifrin get offa my lawn!
 
@robjohn I'm afraid to ask. What did you mean?
 
@feynhat you said you were irregular. I was making a suggestion to help with that.
jokes die in explanation.
 
ugh... I get it.
It was terrible btw.
I thought somewhere in math there was a notion of '(ir)regular fiber', and you were trying to refer to that.
Nope.
 
nope; nothing as high-brow as that. I could have said psyllium, but that would have been too clear in math room.
 
@feynhat: They're called singular fibers, so close.
 
5:36 PM
I got my first dose of vax today.
 
@feynhat Congrats!
 
Yippee!
 
@feynhat which kind? (Pfizer, Moderna, J&J, ...)
 
The Oxford-AstraZeneca one.
 
@feynhat is that a two-dose vaccine?
 
5:44 PM
Yes.
The second one is supposed be administered about 4-6 weeks after the first.
 
5:57 PM
that's good. My son got his second vaccination on Saturday, so our household is completed. One Moderna and two Pfizer
My wife, who had Moderna, was out of work for 3-4 days after the second shot.
My son said he was tired after his second. I did not react to either.
@feynhat let us know how you feel afterwards.
the next day is usually the telling day
 
My mother was sick for a day or two after her first Oxford shot.
My father and one of my sisters had no issue at all. (But she had already tested positive in December last year and recovered pretty quick).
@robjohn Will.
I am already feeling a bit dizzy, and ofcourse it stings a little at the point(?) where they injected.
 
6:18 PM
is it possible to show the collatz squence starting in $s$ must hit the same value twice?
oh nvm
If the conjecture is false, it can only be because there is some starting number which gives rise to a sequence that does not contain 1. Such a sequence would either enter a repeating cycle that excludes 1, or increase without bound. No such sequence has been found.
it seems it's open
 
Professor @robjohn
I request your review of my this proof please math.stackexchange.com/a/4135318/266435
It is to prove that a group with no proper subgroup is of prime order.
 
did stack just crash for a sec for anyone else?
 
@feynhat yeah smh, I'm exist
 
6:39 PM
You're exist? @Thor
 
i just got pfizer #2. the 5g service in my house has increased in quality
 
Even without a new phone! Spectacular!
 
yeah, i didn't realize my galaxy s5 even had an option to display 5g service.
but here we are.
 
If $L/K$ is a purely inseparable field extension of degree $q$, is it then true that $L^q\subset K$? (and if so why?)
 
did the 5g service improve?
Or was it a harmless lie needed for the joke?
 
6:43 PM
lie needed for the joke. in some parts of the world, maybe not harmless.
 
could i ask a favor, could someone glance at math.stackexchange.com/questions/4131027/spivak-calculus-7-ch-22-convergence-of-a-continued-fraction-sequence/4134805#4134805 and tell me if i am missing something obvious please? i'm trying to understand why it is marked for deletion.
 
Oh I saw it got marked for deletion a couple hours ago
 
i care less about the rep, i'm just curious what is going on.
 
It's been happening for a couple months now
 
beats me
 
6:45 PM
tell me about it.
ok, so it is happening to others as well, that is good to know
thx
 
maybe the cardinal sin of answering a question that didn't include enough context or past attempts.
i trust you'll discuss this in confession
 
the OP added an effort in the comments, i waited an appropriate amount of time before answering...
bless me father...
 
original sin?
 
Yeah I found about this a couple weeks ago
 
we are all born with downvotes inside us.
 
6:47 PM
i'm off to limbo
 
there's a meta thread where you can see all of the deletion undeletion wars
 
ugggh.
 
46
Q: Requests for Reopen & Undeletion Votes (volume 07/2018 - 12/2020)

quidThe purpose of this thread is to help focus the attention of the community on posts that may require reopen and undeletion votes. A request should be posted as an answer below (one request per answer). Some guidelines: Please be polite, and respect the many different viewpoints in our diverse co...

it's sorta depressing
I think I'm over it now
 
i used to answer questions for some personal therapy, now i'll have to go to quora
no exercise for 5 days, this is going to be a problem. line up them psqs...
 
there's also r/askmath
yeah answering easy questions is pretty relaxing for me also
 
6:56 PM
@ShaVuklia what's your defn of purely inseparable
 
@copper It doesn't look deleted to me. I guess the problem is the people who keep posting absolutely zero effort questions. I'm no longer answering those.
 
Hi @TedShifrin, it wasn't deleted, but has Delete (1) on it. The OP added some effort in a comment which is good enough for me.
I have to avoid repetitive exercise for 5 days, so I will be even crankier than usual :-)
 
Ah. And great news … Not. Bicycling is repetitive exercise? Walking? What isn't?
 
I am just supposed to walk for the next 5 days. Some hip injection thing.
Exercise is my therapy :-)
and I need lots of it!
 
Ah. I may have to have a lower back surgery … hoping my new orthotics help.
 
7:09 PM
oooh, sorry to hear it.
 
Yes, I'm procrastinating …
 
i believe i understand the procrastination completely
any intervention is something that requires thought.
 
@copper.hat
Yes
Group theory question?
 
7:49 PM
@copper.hat Hubertus
I didn't know that mathematicians had a patron saint
 
@Koro my group theory is not even at an ungergrad level...
 
Hubertus might help me then :)
 
if you don't zoom in it kind of looks like he's wearing a trucker hat in that stained glass
 
8:10 PM
@robjohn i had no idea :-)
almost seems contradictory...
 
and his stag adorns bottles of jaegermeister. that seems somehow appropriate
 
@copper.hat I moved the comments into the question.
@leslietownes Oh, I thought he might also be the patron saint of truckers.
 
@robjohn will do, generally i only make changes if it requires capitalisation (ironic, i know) or some gross & obvious mistake. thanks!
 
@copper.hat yeah, well, there are some zealots out there.
removing the editorialzation
 
i seem to have raised the ire of one lately :-)
 
8:18 PM
it used to be thought kind of rude to edit questions for anything other than typos and such. or at least that is what i had inferred.
but i like pasting further comments into the Q as a CYA against the inquisition
 
Yeah, well, people add context in the comments, so I add a section to their answer labeled as such
 
cool. i will use this approach
 
i guess that is where is feel strain with mse; some habits acquired over a lifetime are not easily changed, partly age but also because they are normal human interaction skills.
and i am not a good bullying target
 
when will you humans learn that normal human interaction skills are just noise in the channel
like PSQs
 
:-)
 
8:23 PM
Yeah. Sometimes the more zealous of those who speak out against question posters not putting effort into their questions, would rather comment, downvote, and flag, rather than improving the question. In this case, simply copying the comment into the question would have sufficed. Perhaps they are worried about giving their effort to the reputation of the OP.
who cares about the reputation? improve the site. improve the questions, when it is easy to do so.
</rant>
 
My turn to rant?
 
<ted rant>
 
sure, why not.
 
i'm waiting ...
 
I'll have to prepare.
 
8:39 PM
 
Jerry calculated the distance wrong but still pole hit Tom
😁
 
9:01 PM
ha, i sometimes do that too. if there's an equation on a blackboard in the background of a scene, or something, i pause and inspect it
most of the time, nonsense
 
9:12 PM
Hello
 
sometimes there is a hidden message in the margin...
 
I don't know how chat is. I speak very bad English(French). Could someone help me. I want to ask a question.
 
9:34 PM
Go ahead & ask, sometimes there is someone here who can answer. Unfortunately I do not speak French.
 
9:45 PM
Je sais un peu de francais
:)
 
I studied it for 5 years, but it has all evaporated unfortunately,
 
10:10 PM
@StéphaneJaouen: c'est pas vraiment facile de répondre si nous ne savons pas quelle est ta question...
 
On pourrait donner une réponse quelconque!
 
certes :D
 
the answer is 5
 
I have to disagree.
Finally.
 
not only with me, either. i asked my daughter how many crackers she wants. she wanted 5.
 
10:13 PM
Too many. She has misbehaved.
 
she used to always ask for two. then she realized that two wasn't a lot
 
@Stéphane a disparu.
 
10:28 PM
@user3733558 salut !
@TedShifrin, je n'avais pas de réponse ; alors je suis parti du chat. Je viens d'arriver sur le site depuis quelques semaines seulement et je suis un peu perdu.
 
Tout le monde se perd. De quoi s’agit-il?
 
@TedShifrin, un de mes posts vient d'être supprimé.
Et je n'ai pas tout compris
Tout est en anglais et je baragouine très mal l'anglais
 
Ça se passe souvent quand ce n'est qu’un exercise sans effort.
 
Il était question de "dupe question"
Qu'est-ce que c'est "dupe question" ?
 
OK, alors, qu'est-ce que vous voulez nous poser?
Une question déjà posée.
 
10:35 PM
En français, "une question de dupe" a un sens très fort !
 
Duplicate
 
la question est un doublon, une question déjà posée dans le passé, avec des réponses satisfaisantes
 
En Anglais, "dupe" signifie seulement "question déjà posée" ?
Sans la connotation très forte du français ?
 
C’est un peu d’argot pour dupliqué …
 
"dupe" est juste la version courte de "duplicate"
 
10:38 PM
Ouf !
Je suis soulagé.
 
Il ne faut pas se fâcher
 
Ce n'est pas facile du tout quand on connait très mal l'anglais
très mal l'anglais d'une part, et le site lui-même d'autre part.
 
Il vous reste beaucoup à apprendre :)
Alors, une question de maths?
 
vous voulez que je vous pose une question de maths ?
C'était une question de maths , celle que j'ai posée.
 
Si vous en avez une.
 
10:41 PM
Sur ce, bonne nuit à tous
 
Bonne nuit.
 
Non, je n'ai pas de question de maths, Ted. J'avoue que cela m'a un peu désarçonné.
peut-être combien font 2+2? (:))
 
Ok … trop difficile pour moi!
 
Je trouve en effet que c'est une question très profonde (:))
 
Il y a @Astyx qui est français et qui se trouve souvent ici.
 
10:44 PM
c'est la première fois que je viens sur le chat
merci pour l'info sur Astyx
 
Comme ça vous apprendrez encore de l’anglais.
 
je ne veux pas vous déranger davantage. J'utilise google traduction.
je suis très impressionné par google traduction.
 
Je suis ravi de ne pas avoir oublié tout mon français!
 
vous écrivez très bien, j'ai cru que vous étiez français
D'où êtes vous ?
 
J’ai bien étudié le français. Il y a 40 ans j'ai donné des conférences en français à Paris.
Je suis américain.
 
10:48 PM
je suis tellement désarçonné que je n'avais même pas regardé votre nom, je vous ai pris pour un français. Enchanté.
Je vis près de Paris, j'y travaille
 
C'est un nom russe :) Enchanté, et bienvenu.
 
merci, je ne veux pas abuser de votre temps
 
OK, une autre fois!
 
bonne nuit et merci beaucoup de m'avoir rassuré. See you soon
 
A tout à l’heure!
 
10:50 PM
A la prochaine !
 

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