Is the work-done by a magnetic field on a moving point charge zero?
Work is not done by the magnetic field?
How to mathematically evaluate a string like "2-1" to produce "1"? Custom attributes - Yea or nay? How can I stop the symbolic x coords to be plotted twice? I have created a bar diagram similar to:   But at a certain width the symbolic x coords are plotted twice. How can I manage the x axis correctly?  Here is my mini example:  \documentclass[12pt,a4paper,]{scrartcl} \usepackage{a4wide} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[ngerman]{babel} \usepackage{graphicx} \usepackage{tikz} \usepackage[miktex]{gnuplottex}  \usepackage{pgfplots}    \begin{document}     \begin{figure}         \begin{tikzpicture}         \begin{axis}[%         width=1\linewidth,         height=0.5\linewidth,         axis x line=center,         axis y line=left,         symbolic x coords={CP-Schelle,Mistel-Schelle V2,Mistel-Schelle V4,Mistel-Schelle V4.2D,Gewickelt nach Inspire},         enlargelimits=true,         ymin=0,         nodes near coords,         x tick label style={         font=\small,         text width=1cm,         align=center         },         ybar]         \addplot[color=gray, fill] coordinates {(CP-Schelle,1.000)};         \addplot[color=blue, fill] coordinates {(Mistel-Schelle V2,2.459)(Mistel-Schelle V4,3.318)(Mistel-Schelle V4.2D,2.243)(Gewickelt nach Inspire,1.782)};         \end{axis}         \end{tikzpicture}     \end{figure}      \begin{figure}         \begin{tikzpicture}         \begin{axis}[%         width=0.6\linewidth,         height=0.5\linewidth,         axis x line=center,         axis y line=left,         symbolic x coords={CP-Schelle,Mistel-Schelle V2,Mistel-Schelle V4,Mistel-Schelle V4.2D,Gewickelt nach Inspire},         enlargelimits=true,         ymin=0,         nodes near coords,         x tick label style={             font=\small,             text width=1cm,             align=center         },         ybar]         \addplot[color=gray, fill] coordinates {(CP-Schelle,1.000)};         \addplot[color=blue, fill] coordinates {(Mistel-Schelle V2,2.459)(Mistel-Schelle V4,3.318)(Mistel-Schelle V4.2D,2.243)(Gewickelt nach Inspire,1.782)};         \end{axis}         \end{tikzpicture}     \end{figure}  \end{document} For bash script, I can use "$@" to access arguments. What's the equivalent when I use an alias? Is there a constructive way to exhibit a basis for $\mathbb{R}^\mathbb{N}$? Assuming the Axiom of Choice, every vector space has a basis, though it can be troublesome to show one explicitly. Is there any constructive way to exhibit a basis for $\mathbb{R}^\mathbb{N}$, the vector space of real sequences? How to check if a string "StartsWith" another string? Is the series $\sum_{1}^{\infty}\frac{1}{p_{j}}$ where $p_{j}$ is the $j$th prime convergent? Does the series $\sum_{n=1 }^{\infty}1/p_{j} $ of  reciprocal primes converge?  Experimentally, it seems convergent. If we had an airtight container that was large enough, say extended out to the Karman line, would there still be a pressure gradient? If we assume that the pressure at the bottom was $1\ \mathrm{atm}$, would it have the same exact pressure gradient at 6 miles up on the outside? This is assuming that the gravity is still $9.8\ \mathrm{m/s^2}$. How do I trim a string in JavaScript? That is, how do I remove all whitespace from the beginning and the end of the string in JavaScript? Adding objects algorithm in Objective-C Every $R$-module is a quotient of a free module I'm reading through my notes, and I have a theorem as the title says. As proof I have only a picture.    where $v:m\mapsto(0,...,0,1,0,...,0)$ and 1 is at $m$-th position. I know, that $\oplus_M R$ is a free module generated by set  $M$, but is this all? I do not see how the statement is proved. How can I search for special characters? Situation: It started out as me  for the literal string C-c in  but it ended up omitting the - sign and showing results which contained the strings C/C++ and C &amp; C++.  is an example of a post which contains that string of characters (yet fails to show up in the results).  Things I've tried:   post suggests that I can use the undocumented code: operator, but when I do that, it just wraps the whole term in double quotes like .  As @terdon in Unix &amp; Linux chat has , using this  does yield some relevant results, but it doesn't show me  that is supposed to be there. edit: It appears that the Symbolhound query no longer returns that result.  Finally,  says that you can search for literal characters, but as you can see:    Quoted phrases are exact matches except for case-sensitivity, for example, you can search  or .  The second example (symbols) leads to 0 results.  So by now I assume that the search engine has changed (but the old documentation still lingers on this site). Is there a method for me to search for strings that include special (or is it literal?) characters? Why my U.S. B1 Visa got refused under 214 (b)? I went for B1 U.S. Visa at the U.S. Embassy in Delhi.   Interviewer: *Good Morning*. Me: *Good Morning* Interviewer: *What is your designation?* Me: *I am a Software Engineer.* Interviewer: *What is the name of your company?* Me: *It is XXX (I replied).* Interviewer: *What is the name of your client?* Me: *It is YYY (I replied).* Interviewer: *Have you ever been to U.S. before?* Me: *NO* Interviewer: *Have you ever been abroad before?* Me: *NO*   At this point he rejected my Visa with letter mentioning 214 (b) as the reason. I don't know why he actually rejected it.  But, I have decent 2+ years of experience with my company. And, I was going on a business meeting with the client. I would have come back after 2 weeks.  I don't know if re applying will help. How can I secure an Ethernet-over-power network? I just bought myself an Ethernet-over-power adapter, and plugged it in. It seems to be working great, but now I'm concerned that my neighbours may be able to access my network.  I live in a rowhome complex; is it possible they can access my network? If so, how can I secure it? How to find previous boot log after Ubuntu 16.04+ restarts? My question is, how can I find boot log from previous system boot attempt?  Today when first powering on my PC, boot process stopped on Ubuntu logo, when I pressed Esc I have seen several lines containing some kernel error and restart required at the bottom, so I pressed Ctrl+ALt+Del and next boot went OK without problems.  I have trouble finding messages from the screen I have seen during the first unsuccessful boot. Should I have taken picture to my phone?  /var/log/boot is there but empty, I searched  and  for strings I remembered with today's date like error but found nothing familiar to what I have seen on previous boot screen.  $ journalctl -b -1 gives me only kernel messages during boot, I can find that elsewhere too, and they are not what was appearing on screen during boot, journalctl is useless for me, I am looking for messages appearing on screen during boot time.  For now, only option is take a photo of write the message on paper. execute command on a defined range of directories Is it possible to 'partition' a directory listing - say in to blocks of some number, to perform different actions on each 'range'?  For example, lets say I have the following directories inside another folder:  $ ls test abc/ def/ hij/ klm/ nop/ qrs/ tuv/ wxy/ zzz/   And I want to perform some action on the first 3 directories, another on the second 3, and so on.  My thought was that perhaps a loop across numbers would work, based on the output of something like ls | nl (but before anyone mentions it, I know parsing ls is a no-no!)  This obviously doesn't work, but illustrates my point I hope:  for dir in `ls | nl`;  do     do-something-with ${dir{1..3}} # Where $dir has taken on some numerical value linked to the folder)     do-something-with ${dir{4..6}}  # And so on...     do-something-with ${dir{n-3..n}}  done   The folders I intend to actually do this on, can be worked on in any order (i.e. the final splits can be totally arbitrary), but they have no logical naming consistency - by which I mean they can't be organised sensibly alphabetically or numerically based on any key within the directory name themselves. No surname on passport and applying for Japanese Visa How can I determine the sudo password? What is the default password of the sudo? I visit some forums, it tells that the default password is password, but it doesn't work, how can I determine the password? Seedable JavaScript random number generator The latex file coding is not there but the pdf file is there I wrote all my coding in the .tex file. The next day when I opened it the coding is all gone and the pdf file is opening with it and is displayed as an output. How do I bring back my coding?