I want to make an overline via " $\overline{O}$VERLINE " above a letter but this letter then appears in an italic shape. How do I avoid this?
If I want to draw an overline over some text, not an equation, how can I do it? \overline seems to only work in math mode, and when used outside of math mode, it automatically says "Missing $ inserted".
Evaluate $\mathop {\lim }\limits_{x \to 0} \left( {{1 \over {{{\sin }^2}x}} - {1 \over {{x^2}}}} \right)$ I tried l'Hospital but that will require a lot (and I mean A LOT!!!) of differentiating  Is there a shortcut? $$\mathop {\lim }\limits_{x \to 0} \left( {{1 \over {{{\sin }^2}x}} - {1 \over {{x^2}}}} \right)$$  Thanks in advance The problem from Burton: show that the equation $n^2 + (n+1)^2 = m^3$ has no solution in the positive integers.  So far, I can see that gcd($n$,$n+1$)$=1$ and $m \equiv_4 1$ and $m=a^2 + b^2$ for some integers a,b. I'm guessing I need to reach a contradiction.  At this point, I am stuck. Any hints? Latex create a second keywordstyle using listing doesn't work My wireless/WiFi connection does not work. What information is needed to diagnose the issue? Your situation   You have successfully installed Ubuntu.  You have just downloaded and booted Ubuntu live media.  The latest LTS (see also ) or latest non-LTS release are preferred. See the list of  that are currently supported.) You upgraded your Ubuntu installation to the latest release that the software updater offered you. WiFi worked before, but not now on the new release. You  to new hardware.   Your problem   The wireless of your laptop or desktop is not working. You tried switching the wireless switch off and on and you tried rebooting several times, but you don't see any WiFi access points. You can see your wireless access point, but you cannot establish a connection. You want to analyze the problem, but you don't know where to start or what information you can provide.   This question and answer was written to give people the wireless script that will provide the information needed in most cases to diagnose their wireless issue's.   Related questions I always see pictures of the solar system where our sun is in the middle and the planets surround the sun. All these planets move on orbits on the same layer. Why? How to create a matrix with 20 columns in latex The code below works,  but when I add 10 more columns, it does not. So, how can I add ten more columns to the matrix below?  \documentclass{article} \usepackage{amsmath} \begin{document}  \begin{equation} \begin{bmatrix}  1 &amp; 0 &amp; 0 &amp; 0  &amp; 0 &amp; 1 &amp; 0 &amp; 0 &amp; 1 &amp; 0  \end{bmatrix} \end{equation}  \end{document} Is mass converted into energy in exothermic chemical/nuclear reactions?  My (A Level) knowledge of chemistry suggests that this isn't the case. In a simple burning reaction, e.g.   $$\mathrm{C + O_2 \to CO_2}$$  energy is released by the $\mathrm{C-O}$ bonds forming; the atoms lose potential energy when they pull themselves towards each other, in the same way that a falling object converts GPE to KE. There are the same number of protons, electrons etc. in both the reactants and products. I would have assumed that this reasoning extends to nuclear fission/fusion as well, but one physics textbook repeatedly references very small amounts of mass being converted into energy in nuclear reactions.  So I just wanted to know if I was wrong about either of these types of reactions, and if so, what mass is lost exactly? Difference between "been to" and "been in" Is Innate Spellcasting counterspellable? On p.85 of Xanathar’s Guide to Everything, there’s a section clarifying that you need to perceive a spell being cast (by either a verbal, somatic or material component) in order to counterspell it.  It then goes on saying this :     If the need for a spell’s components has been removed by a special ability, such as the sorcerer’s Subtle Spell feature or the Innate Spellcasting trait possessed by many creatures, the casting of the spell is imperceptible.   The thing is that many monsters’ Innate spellcasting specify that only material components are discarded (not verbal or somatic). So I am not sure whether you can actually counterspell innate spellcasting when the stat block only mentions removing material components.  There seems to be  supporting that such spells could be counterspelled (although it is confusing a bit).  It basically comes down to whether the above quote’s “many creatures” refers to all creatures with innate spellcasting, or only those that forgo all spell components to innanely cast. So, which is it ? arXiv is smart enough to detect whether your PDF is generated by LaTeX. If it is, arXiv asks for the sources of the PDF instead of the PDF file itself. This is really annoying and inconvenient.  I ask a way to fool the arXiv and avoid PDFs being detected as generated by LaTeX (even if they were indeed).  I have tried this: : "create a pdf from word and then simply insert pages from your article, and delete the word's page".  And it did not work. Can anyone help me with this problem?     Let $f:[0,\infty)\longrightarrow \mathbb R$ be a continuous function such that for each $x&gt;0$, we have $\lim_{n\to \infty}f(nx)=0$. Then prove that $\lim_{x\to \infty}f(x)=0$.   Our teacher told first to prove Baire's theorem, and then show that this is a consequence of that theorem. I proved Baire's theorem, and I spend a few hours thinking on how Baire's theorem is related to this problem, but I couldn't find anything. I'd really appreciate your help. The system cannot find the file specified I have just downloaded WinEdt and written my first code, but it will not run because I keep getting the following error.  I am at a loss as to how to fix this.  Error launching Console Application PDFLaTeX ... Command Line: pdflatex.exe --interaction=errorstopmode --synctex=-1 &quot;practice.tex&quot; Startup Folder: C:\Users\shahand\WinEdt Team\WinEdt 8 The system cannot find the file specified. So, I'm using a script I've made to convert videos to the webm format. A certain program calls the script, sending %f which is the full, absolute file name of the video, like this:  converter.sh %f   where %f has two possible extensions, .avi or .mpg.  # /bin/bash ffmpeg -i $1 `dirname $1``basename $1 avi`webm &amp;&amp; rm $1   It currently works perfectly when $1 contains a .avi file, because basename removes the .avi extension. When $1 ends with .mpg instead, the result is .mpgwebm.  How can I modify that script to be able to receive those two possible different formats?    Resuming: If $1 is /somedir/video.avi, the script should do:  ffmpeg -i /somedir/video.avi /somedir/video.webm   And if $1 is /somedir/video.mpg, the script should do:  ffmpeg -i /somedir/video.mpg /somedir/video.webm   I know this might be fool for some people, but I'm kind of new with the bash. Proof that the nth root of a rational s/t is irrational unless s and t are perfect nth powers I'm trying to prove that $\sqrt[n]{\frac{s}{t}}$ is irrational unless both s and t are perfect nth powers. I have found plenty of proofs for nth root of an integer but cannot find anything for rationals. Also trying to work up from the proofs I have found is rather difficult.  My lecturer wants me to prove this using uniqueness of prime factorisation but I also have no idea where to start with that.   Any help is greatly appreciated. NOTE: Signing up or Logging in via OpenID is no longer officially supported from any of our sites. Currently,  is still on the internet, but we are in the process of completely removing it.    Stack Overflow was an early and strong supporter of . We built our sign up/log in flow around it. We were idealistic and had , but these hopes weren't realized. Over the years people have wondered if  is . We've had to remove support as OpenID providers  or .  The time has come to part ways. The reality is OpenID support has created a ton of complexity in our codebase and the number of users actively using OpenID simply don't justify that cost. Users have spoken with their actions. You prefer Google, Facebook and Stack Exchange (aka email/PW) based account auth.     Of our 9,813,747 accounts around one-tenth of a percent are actively using OpenID (defined as having visited a site in the past 12 months). If you include all the inactive accounts it is still less than 2.9% of all accounts.  So, what is the plan?   DONE - Remove the ability to create a new account with most OpenID providers DONE - Add the ability to  DONE - Convert Launchpad (used on  ) to OAuth DONE - Remove creating new accounts with Steam from  (Steam removed support for OAuth. Only 454 accounts that use Steam have visited Arqade in the past 6 months.) DONE - We will email all users that rely on deprecated OpenID credentials and request that they  DONE - Run an announcement banner for any user who signs in with deprecated OpenID credentials urging them to  DONE - End support for logging in via OpenID  In progress - Remove  (note: only 0.2% of authorized sites in the last year have been non-Stack Exchange sites.)   Obviously, if your account relies on OpenID, then make life easy and go now and .   If you've forgotten what you credentials you use to login, then  to refresh your memory. If you don't see one of the three account types shown in the image below (Google, Facebook or Stack Exchange) then click the "add more logins" button to add one of them to your account.    Remember, SE OpenID accounts are really email/pw accounts handled through complicated OpenID code path. They will be migrated to a simpler email/pw only code path as a part of this change. No extra work required on your part. Two paths that show that $\frac{x-y}{x^2 + y^2}$ has no limit when $(x,y) \rightarrow (0,0)$ Background: I'm giving a presentation to colleagues at work on hypothesis testing, and understand most of it fine but there's one aspect that I'm tying myself up in knots trying to understand as well as explain it to others.  This is what I think I know (please correct if wrong!)   Statistics that would be normal if variance was known, follow a $t$-distribution if the variance is unknown CLT (Central Limit Theorem): The sampling distribution of the sample mean is approximately normal for sufficiently large $n$ (could be $30$, could be up to $300$ for highly skewed distributions) The $t$-distribution can be considered Normal for degrees of freedom $&gt; 30$   You use the $z$-test if:   Population normal and variance known (for any sample size) Population normal, variance unknown and $n&gt;30$ (due to CLT) Population binomial, $np&gt;10$, $nq&gt;10$   You use the $t$-test if:   Population normal, variance unknown and $n&lt;30$ No knowledge about population or variance and $n&lt;30$, but sample data looks normal / passes tests etc so population can be assumed normal   So I'm left with:    For samples $&gt;30$ and $&lt;\approx 300$(?), no knowledge about population and variance known / unknown.   So my questions are:   At what sample size can you assume (where no knowledge about population distribution or variance) that the sampling distribution of the mean is normal (i.e. CLT has kicked in) when the sampling distribution looks non-normal? I know that some distributions need $n&gt;300$, but some resources seem to say use the $z$-test whenever $n&gt;30$... For the cases I'm unsure about, I presume I look at the data for normality. Now, if the sample data does looks normal do I use the $z$-test (since assume population normal, and since $n&gt;30$)? What about where the sample data for cases I'm uncertain about don't look normal? Are there any circumstances where you'd still use a $t$-test or $z$-test or do you always look to transform / use non-parametric tests? I know that, due to CLT, at some value of $n$ the sampling distribution of the mean will approximate to normal but the sample data won't tell me what that value of $n$ is; the sample data could be non-normal whilst the sample mean follows a normal / $t$.  Are there cases where you'd be transforming / using a non-parametric test when in fact the sampling distribution of the mean was normal / $t$ but you couldn't tell? How to change file encoding in NetBeans? C++ performance of accessing member variables versus local variables Is it more efficient for a class to access member variables or local variables? For example, suppose you have a (callback) method whose sole responsibility is to receive data, perform calculations on it, then pass it off to other classes. Performance-wise, would it make more sense to have a list of member variables that the method populates as it receives data? Or just declare local variables each time the callback method is called?  Assume this method would be called hundreds of times a second...  In case I'm not being clear, here's some quick examples:  // use local variables class thisClass {     public:         void callback( msg&amp; msg )         {             int varA;             double varB;             std::string varC;             varA = msg.getInt();             varB = msg.getDouble();             varC = msg.getString();              // do a bunch of calculations          }  };  // use member variables class thisClass {     public:         void callback( msg&amp; msg )         {              m_varA = msg.getInt();              m_varB = msg.getDouble();              m_varC = msg.getString();               // do a bunch of calculations         }      private:         int m_varA;         double m_varB;         std::string m_varC;  }; How do I hide the System Reserved partition from the Windows Explorer?    On the above screenshot, I want to get rid of System Reserved (D:). How do I do that?  I will never need to access it from there, why would I need the entry then?  PS: I want to hide it, not delete it.