@robjohn The strange thing is that the person who asked the question knew I had already asked it. We've talked about it several times. I don't know why he just didn't ask me to bump my question. I would have been happy to do so.
@robjohn The hint in the book was to go backwards starting from the contour integral representation. So I never tried to go in the other direction. That was dumb on my part.
@robjohn I'm still able to access that question, but I can't do anything. Is that the way it should be?
@RandomVariable Yes, this is how merging works. One of two copies becomes the main one, and the other one gets locked. Answers are transferred from the latter to the former.
@TedShifrin I want to talk about transversality! Is it just a generalization of Lagrange multipliers, or the calculus of variations or an extension of it, to manifolds? If so, what is Morse theory, (which is what I thought that was)?
Hi, off topic question: Is my reasoning that $f(x)=x^2$ is not uniformly continuous on $\mathbb{R}$ sound? Let $\varepsilon=1. $ Given $\delta>0$, we can choose $x,y>0$ such that $\frac{\delta }{2}<\vert x-y \vert <\delta$ and x,y>\frac{1}{\delta}. Then $\vert x^2 - y^2\vert = \vert x-y\vert \cdot \vert x+y\vert \ge \frac{\delta}{2} \cdot \frac{2}{\delta}=1, $ therefore $f$ is not uniformly continuous.
Does anyone have any sketches of a proof (or applications and examples) of the fact that if $f$ is a function from a subset of $\mathbb{R}^n$ to $\mathbb{R}$ and the gradient of $f$ is bounded, then $f$ is uniformly continuous?
@Bananarama: Depends on where you are going, Downtown Berkeley to Powell Street SF takes about 25 mins. at 10am weekdays. Driving is about the same (with much larger variance), but you need to deal with parking.
@TheSubstitute: If the gradient is bounded the mean value theorem shows that $f$ is Lipschitz.
@RandomVariable You can't delete it? Let me look. I worked the other question and my answer is very similar to achille's. I've left it since it provides more detail, but I may delete it, if it appears to be a problem.
@RandomVariable Closing as duplicate seems to lock the question.
I'm having trouble appreciating the subject, the standard books I find aren't rigorous in that they stick to the real line too much when I want to measure abstract sets, and the Bourbaki-Radon approach just seems too specialized in a different direction, so the subject is pretty annoying
I think there's a mistake in this paper I am reading. They are proving lower and upper bounds for $n\choose{k}$. In the upper bound, they first go about stating $(1+x)^n=\sum_{i=0}^n$ $n\choose{i}$ $x^i$ for every $x$. But then they state, that if we assume $x\ge 0$ we have $(1+x)^n \ge \sum_{i=0}^n$ $n\choose{i}$ $x^i$
I have found an engineering paper (IEEE) where the author claims to have found 7 eigenvalues of a 6by6 matrix. I wonder whether I missed something or if the author made a mistake. would it be on topic for this SE?
@Bananarama generally (e.g., "from eq.(x.y) we have") I would agree. here the equation is 3 pages before and not recalled, I had to deduct it from the appearance of a variable used there.
@robjohn No, I can't delete it. And seemingly no one can delete it. But why does the other question have to link to it twice? If I had known that would happen, I would have just left it alone.
@RandomVariable If I remember correctly, if your question is closed as a duplicate, you need to wait two days before you can delete it yourself. Not sure if merging changes things. I'd think a moderator would be able to delete it, however.
the graphics for my published work is all done in tikz, but i mostly end up using mathematica on the fly. i ended up learning mathematica really thoroughly during my physics undergrad so it's easier for me to code in than anything else.
@robjohn Why would who care? I sent Cody an email asking him why he didn't ask me to bump my question or why he didn't attach a bounty to mine. His response was not very pleasant. So I thought the best thing to do would be to delete the question and pretend this never happened.
@AlexanderGruber In the latest post, most are done with Maple, and the quality is not great. No anti-aliasing. The last two are from Desmos, online calculator. But my favorite is Sage (which I guess uses Python's matplotlib), as seen here: calculus7.org/2013/06/04/real-zeros-of-sine-taylor-polynomials
@DanielFischer They don't vanish. They stay on the site and show up as locked. They are probably excluded from the question lists, but remain accessible via search.
@DanielFischer which is why, for example, there are a few homework-only-tagged things that will remain such (hence, become untagged).
I'm not worried about that, though. More worried about the failure to clean up the tag before Tim Post nukes it tomorrow.
@DanielFischer Exactly, since nobody looks at them anyway. As for others, I downloaded a list of questions that currently have the hw tag, so I can still take a look after the tag is gone.
And this thing definitely did not help the clean up effort. Grumble
@robjohn I might have already mentioned this, but I was working backwards trying to figure out where to place the vertex of the parabola. If I had started from the other direction, I imagine I would have figured it out. Maybe.
@MikeMiller As usual, I suggest the magic bookmarklet which makes the front page interesting at once. Works best if you have some favorite tags, but this is not necessary.
@MikeMiller By design, since I prefer to work with a blank sheet. It also removes questions that were posted less than an hour ago. The combination of two factors means that FGITW solvers of HW work for me, filtering the boring stuff out.
@MikeMiller If you don't want to exclude those, just bookmark the Interesting tab. The JavaScript just takes that page and filters it further.
@900sit-upsaday: Do you know if it is possible to search the DB for questions without a tag? I have a script that searches for homework-only questions, but I don't know if it will work after the purge.
I have asked a community manager, but have not gotten a reply.
@900sit-upsaday There are some sites I like to read but not answer on; is there any chance you have a variant of that that only shows answered questions?
@robjohn When burnination removes the sole tag from a question, it is automatically given untagged. Which is pretty much like any other tag, you can filter for it using the site interface, and edit those questions.
@MikeMiller The "interesting" tab promotes unanswered questions, so using it as a base level would be counterproductive. You can restrict to favorite tags like this
@robjohn Normally they don't exist. They may appear shortly after a mod-initiated migration from another site, if there is no matching tag on the destination site.
@robjohn In case of untagged, there can't be another tag. So the usual tag search works. In general, one can search for [tag name] is:question, and sort by relevance. The system thinks that the most relevant questions are those with only that tag. Example
@900sit-upsaday I, for one, am starting to downvote more. I'm also using my $5$ delete votes (and I'm using my closevotes strategically). A visit to Uber-meta (no umlaut on my keyboard, and I don't feel like internationalizing my layout) in addition to what 900 has said knocked some sense into me.
@pourjour deg(P)=deg(QD+R)=deg(QD)=deg(Q)+deg(D), so deg(Q)=deg(P)-deg(D) which is less than or equal to m-(n+1), since deg(P) is less than or equal to m and deg(D)=n+1
Hi people! I need your help! Here is an old, answered question, but recently I found some mistake... Please take a look at my edited answer. I have added a counter example. May you please figure out what's wrong? Again, the evaluation of the integral is due to @DanielFischer (from an even older question). Thanks a lot!
I have a dumb question: Why doesnt the Flinn Hills series \sum_{n=1}^\infty \frac{1}{n^3 \sin^2 n} converge by comparison with the series over all 1/n^3 ?
@nullgeppetto If you found a counterexample to an answer, add it either as a comment to the answer or into the original question. Don't add to the question in an answer, because that might get lost.
@anorton, I see, and you're right, but my answer is not new. There was there before the counterexample. I've also added a comment to the @p.s.'s answer, who originally gave an answer! Thanks!
Guys and gals, I feel super stupid but after trying to find a way to show that $\sqrt{\frac{\sum(x_i-y_i)^2}{n}} \geq \sum \frac{|x_i-y_i|}{n}$ for far too long - anybody got a hint?
@JasperLoy they do repeat what the op said, but henry additionally says "knowing k*0=0" which does clarify that indeed we need to know that first, although henry failed to emphasize this fact like you did even though it's really what op's question was supposed to be about, and henry additionally points out his hunch about what the real issue is. still waiting for verification on that one though.
@JasperLoy I'm not arguing that you do. if anything, your answer is useful but could potentially be improved (waiting on henry's hunch), and adam's answer communicates no new information yet his is the one most upvoted
@MikeMiller Indeed, he was quiet provocative and rude on meta.math.SE (with T. Bongers for e.g.) and he downvoted a lot of good answers with silly excuses.
