I am new to this site.  While browsing questions, I've found some to be very interesting.  Can anyone tell me how to track those questions?
What does bookmarking a question mean? How do you bookmark a question? Do users get updates on their bookmarked questions? Are my bookmarks publicly visible? How do you see your own bookmarks? How do you see other users' bookmarks? How do you see which users have bookmarked a particular question? What impact does the bookmark system have on the voting system? Can I &quot;un-bookmark&quot; a question? Can I search within my bookmarks?
C++ equivalent of java's instanceof What is the preferred method to achieve the C++ equivalent of java's instanceof? Say I have a variable named choice it is equal to 2. How would I access the name of the variable? Something equivalent to  In [53]: namestr(choice) Out[53]: 'choice'   for use in making a dictionary. There's a good way to do this and I'm just missing it.  EDIT:  The reason to do this is thus. I am running some data analysis stuff where I call the program with multiple parameters that I would like to tweak, or not tweak, at runtime. I read in the parameters I used in the last run from a .config file formated as  filename no_sig_resonance.dat  mass_peak 700  choice 1,2,3   When prompted for values, the previously used is displayed and an empty string input will use the previously used value.  My question comes about because when it comes to writing the dictionary that these values have been scanned into. If a parameter is needed I run get_param which accesses the file and finds the parameter.   I think I will avoid the problem all together by reading the .config file once and producing a dictionary from that. I avoided that originally for... reasons I no longer remember. Perfect situation to update my code! To prove the convergence of the p-series   $$\sum_{n=1}^{\infty} \frac1{n^p}$$  for $p &gt; 1$, one typically appeals to either the Integral Test or the Cauchy Condensation Test.  I am wondering if there is a self-contained proof that this series converges which does not rely on either test.    I suspect that any proof would have to use the ideas behind one of these two tests. I have a little problem with the placement of my picture. I want to insert it at the end of the introduction chapter but its place is not where I want.   I think the problem become from the:  \begin{figure} ... \end{figure}   Because when I insert the picture without using \begin{figure}... the picture is at the end of the chapter as I want.   Look the picture below. How can I get Gnome3 to remember my session? I am running Gnome3, but I had the same problem with Unity, on Ubuntu 12.04.  I have a fairly elaborate setup I enjoy using day-to-day. A LibreOffice spreadsheet with everyone's extension numbers; a window with reference data I use regularly; two mulit-tabbed Konsole/Terminal windows with several remote systems sessions, firefox with a set of open tabs, and so on. But whenever I log out, when I return, I must set up everything from scratch. I remember the good 'ol days, when I rebooted, I'd re-log in, and all my windows came back up in the same places as they were when I logged out, and my Konsole/Term would come up with the same remote logins as before.... I'd have to re -setup  some of my programs, but that's better than having to move every win into place, and resize them, etc.  How do I get this functionality back? Suspending with root on USB I have a laptop running Ubuntu 14.04 from a root file system on USB storage. This is not working well, because after wake up from suspend, ext4 will frequently try to write to the root file system before USB is ready.  Here is what I see in the kernel log when this happens, notice how I get a bunch of I/O errors on sda1, and then one second later the USB storage drive is finally detected by the kernel.  [ 2826.517419] wlan0: associated [ 2826.517452] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready [ 2827.575371] EXT4-fs warning (device sda1): ext4_end_bio:317: I/O error -5 writing to inode 1733735 (offset 0 size 0 starting block 12629950) [ 2827.575380] Buffer I/O error on device sda1, logical block 12629694 [ 2827.575400] EXT4-fs warning (device sda1): ext4_end_bio:317: I/O error -5 writing to inode 3148603 (offset 0 size 8192 starting block 12844470) [ 2827.575404] Buffer I/O error on device sda1, logical block 12844212 [ 2827.575411] Buffer I/O error on device sda1, logical block 12844213 [ 2827.575448] EXT4-fs warning (device sda1): ext4_end_bio:317: I/O error -5 writing to inode 3015015 (offset 0 size 90112 starting block 6588832) [ 2827.575453] Buffer I/O error on device sda1, logical block 6588576 [ 2827.575461] Buffer I/O error on device sda1, logical block 6588577 [ 2827.575465] Buffer I/O error on device sda1, logical block 6588578 [ 2827.575469] Buffer I/O error on device sda1, logical block 6588579 [ 2827.575473] Buffer I/O error on device sda1, logical block 6588580 [ 2827.575477] Buffer I/O error on device sda1, logical block 6588581 [ 2827.575481] Buffer I/O error on device sda1, logical block 6588582 [ 2828.857284] sd 0:0:0:0: [sda] No Caching mode page found [ 2828.857293] sd 0:0:0:0: [sda] Assuming drive cache: write through   At first there is no visible indication outside of the kernel log, that the problem has triggered, but if I let Ubuntu stay running beyond this point, then the file system will get errors and eventually switch to read only mode. At that point I have to reboot into recovery mode and run fsck.ext4 manually from a root shell in order to repair the file system.  Is there some setting I can change such that access to the root device after waking from suspend can be delayed until the USB drive is ready? How to assign same Data to multiple object copies I have to format my entire disk and reinstall Ubuntu.  I have installed a lot of software on my current system. And I will have to reinstall all those updates, drivers and applications too.  Is there any way I can make an .iso image of my installed Ubuntu along with all the software, preferences, drivers etc in it ?  Is there any way I can back up my whole OS along with all its software, drives, updates and all ? A friend of mine was trying to explain to me how all infinities are equal. For example, they were saying that there are the same amount of numbers between $0$–$1$ as there are between $0$–$2$.  The way they explained it, you could prove that there are the same amount of numbers by getting a match to each number.  For example, for any number in the range from $0$–$2$, you can find a matching number in the range $0$–$1$ by dividing the number by 2. In every case, the ending number will end up between $0$–$1$. In addition, if you multiplied any number in the range of $0$–$1$ by 2, you will always end up with a number between $0$–$2$ Therefore, there should be the same infinite amount of numbers between  $0$–$1$ as there are between $0$–$2$.  Is this principle accurate? The problem that I had with it was, if in-fact there are the same amount of numbers between 0 and 1 as there are between 0 and 2, why is 2 greater than 1? Problems with french accents automatically understood by LaTeX Subdivision surface modifier creates pinching at corners I've only been 3D modelling for a few days now, so this may just be a newbie mistake:  However, because this model is for use in a game I am trying to stay away from proximity loops for performance reasons. Instead, I have used edge creases to maintain the structure of the model. It has led to certain vertices not being affected by the subsurf modifier, causing undesirable lighting at high subsurf levels.  Manually moving each point in a bit seems kind of sloppy but I'm not too sure what the best way to go about this is.  If any more information is needed I'll give what I can, thanks in advance :) Scoping in assigning a derivative I was just reading Harry Potter and the Deathly Hallows, and I was wondering, when Hermione Granger changed into Bellatrix Lestrange, she should've obtained the Dark Mark, temporarily.  Now, my question is: would the Dark Mark work if pressed? Is Con modifier × level added to HP every level-up? diameter on a compact metric space I have troubles showing the following:  Let $(X,\rho)$ be a compact metric space and $F \subset X$ a closed subset. Prove that if diam $F &lt; \infty$, then there exist $x_{0}, y_{0} \in F$ such that diam $F= \rho(x_{0},y_{0})$.  It looks so trivial yet hard to find the trick. In biblatex, treat periods in journal as abbreviation dots I would like to consistently have a comma between the journal and volume number for article references using biblatex with biber as the backend. Unfortunately, the punctuation between the journal and volume is not consistent. Journals whose last word is abbreviated have no comma between the journal and the volume, and the word "Vol." is capitalized. Journals whose last word is not abbreviated have a comma and the word "vol." is not capitalized. I can fix the capitalization by un-commenting the commented lines in the below MWE, but the comma problem is quite perplexing. Apologies if this fix is in an answer somewhere, but I cannot find it (or at least, I don't know what to search for!).  Current output: [1] First Author. “Blah Blah 2”. In: Am. J. Phys. Vol. 72, no. 3 (Mar. 2004), pp. 367–375. [2] Second Author. “Blah blah”. In: Energy Fuel, vol. 27, no. 12 (Dec. 2013), pp. 7778–7789.  Expected output: [1] First Author. “Blah Blah 2”. In: Am. J. Phys., vol. 72, no. 3 (Mar. 2004), pp. 367–375. [2] Second Author. “Blah blah”. In: Energy Fuel, vol. 27, no. 12 (Dec. 2013), pp. 7778–7789.  MWE:  \documentclass{article} \usepackage{filecontents} \usepackage[     backend=biber,     citestyle=numeric-comp, ]{biblatex} \addbibresource{\jobname} % \DefineBibliographyStrings{english}{%     % volume = {\lowercase{v}ol\adddot}, % avoid capitalization after dots. % } \DeclareFieldFormat[article]{volume}{\bibstring{volume}\addspace #1} \DeclareFieldFormat[article]{number}{\bibstring{number}\addspace #1} \renewbibmacro*{volume+number+eid}{%   \printfield{volume}%   \setunit{\addcomma\space}%&lt;---- was \setunit*{\adddot}%   \printfield{number}%   \setunit{\addcomma\space}%   \printfield{eid}} \renewbibmacro*{journal+issuetitle}{%   \usebibmacro{journal}%   \setunit*{\addcomma\addspace}%&lt;---- was \setunit*{\addspace}%   \iffieldundef{series}     {}     {\newunit      \printfield{series}%      \setunit{\addspace}}%   \usebibmacro{volume+number+eid}%   \setunit{\addspace}%   \usebibmacro{issue+date}%   \setunit{\addcolon\space}%   \usebibmacro{issue}%   \newunit}  \begin{filecontents*}{\jobname.bib} @article{York2004, author = {Author, First}, journal = {Am. J. Phys.}, month = mar, number = {3}, pages = {367--375}, title = {{Blah Blah 2}}, volume = {72}, year = {2004} } @article{Baumgardner2013a, author = {Author, Second}, journal = {Energy Fuel}, month = dec, number = {12}, pages = {7778--7789}, title = {{Blah blah}}, volume = {27}, year = {2013} } \end{filecontents*}  \begin{document} \nocite{*} \printbibliography \end{document} Proof of the L'Hôpital Rule for $\frac{\infty}{\infty}$ I ask for the proof of the L'Hôpital rule for the indeterminate form $\frac{\infty}{\infty}$ utilizing the rule for the form $\frac{0}{0}$.   Theorem: Let $f,g:(a,b)\to \mathbb{R}$ be two differentiable functions such as that:  $\forall x\in(a,b)\ \ g(x)\neq 0\text{ and }g^{\prime}(x)\neq 0$ and $\lim_{x\to a^+}f(x)=\lim_{x\to a^+}g(x)=+\infty$ If the limit $$\lim_{x\to a^+}\frac{f^{\prime}(x)}{g^{\prime}(x)}$$ exists and is finite, then  $$\lim_{x\to a^+}\frac{f(x)}{g(x)}=\lim_{x\to a^+}\frac{f^{\prime}(x)}{g^{\prime}(x)}$$  My attempt:  Since $\lim_{x\to a^+}f(x)=+\infty$, $$\exists \delta&gt;0:a&lt;x&lt;a+\delta&lt;b\Rightarrow f(x)&gt;0\Rightarrow f(x)\neq 0$$  Let $F,G:(a,a+\delta)\to \mathbb{R}$, $F(x)=\frac{1}{f(x)}$, $G(x)=\frac{1}{g(x)}$. Then by the hypothesis $\lim_{x\to a^+}F(x)=\lim_{x\to a^+}G(x)=0$, $$\forall x\in(a,b)\ \ G(x)\neq 0\text{ and }G^{\prime}(x)=-\frac{1}{g^2(x)}g^{\prime}(x)\neq 0$$ The question is, does the limit $$\lim_{x\to a^+}\frac{F^{\prime}(x)}{G^{\prime}(x)}=\lim_{x\to a^+}\frac{-\frac{1}{f^2(x)}f^{\prime}(x)}{-\frac{1}{g^2(x)}g^{\prime}(X)}=\lim_{x\to a^+}\frac{g^2(x)f^{\prime}(x)}{f^2(x)g^{\prime}(x)}$$ exist?   The limit $$\lim_{x\to a^+}\frac{f^{\prime}(x)}{g^{\prime}(x)}$$ exists by the hypothesis but we don't know if the limit $\displaystyle\lim_{x\to a^+}\frac{g^2(x)}{f^2(x)}$ exists to deduce that the limit $$\lim_{x\to a^+}\frac{F^{\prime}(x)}{G^{\prime}(x)}$$ exists to use the L'Hôpital Rule for the form $\frac{0}{0}$.  EDIT: After discussing it with other users in the site, we came to the conclusion that this proof is only partial and can't logically be continued to yield the Theorem.  As a result, the rule for the $\frac{0}{0}$ form can't be used to proove the rule for the  $\frac{\infty}{\infty}$ form. Mr. Tavares and myself have already given two different proofs (with the pretty much the same main idea) of the Theorem in question using Cauchy's Mean Value Theorem. You can read them below. You can also read the proof Rudin gives for a stronger version of the Theorem (that does not suppose that $\lim_{x\to a^+}f(x)=+\infty$) in his book Principle of Meathematical Analysis. If you have any objections in either proofs please let me know. Thank you. There is this puzzling thing that is called : paradoxically, warm (35°C) water freezes faster than cold (5°C) water.  As a physisist, I've been asked about it several times already. And I have no definite answer to that, apart from the standard: "there are many things that can influence it".  So, does anyone knows about the status or progress on that effect? Any recent reviews, publications or other references? Is there a way to access an iteration-counter in Java's for-each loop? Is there a way in Java's for-each loop  for(String s : stringArray) {   doSomethingWith(s); }   to find out how often the loop has already been processed?  Aside from using the old and well-known for(int i=0; i &lt; boundary; i++) - loop, is the construct  int i = 0; for(String s : stringArray) {   doSomethingWith(s);   i++; }   the only way to have such a counter available in a for-each loop? I have a major problem that I hope someone can help with. On my Google Maps feature under my Location History it shows a location that I was never at at any point, but when my wife happened to see that location she doesn't believe me that the GPS could be wrong and pinpoint that location if I was never there.  I was first wondering myself how could that could be possible if I was never there or my phone was never at that location that was 35 miles away from me and second is there any way I could prove the GPS being wrong? Can I contact Google Maps and can they give an official printout of that certain day and every location I was? I really need to prove my honesty to her and hope there is a way.