X-Wing vs Star Destroyer game won't run
How to run shell script via terminal
How do I mirror the faces of a cube (edit all of them when I edit one)? Custom macro for multicolumn with & without xparse The following example has two normal LaTeX \newcommand macros and two xparse \NewDocumentCommand for specifying multicolumn text. The only difference between each pair of commands is one has the alignment character as part of the macro and one does not.  However, the xparse version that requires the alignment character to be outside of the macro does NOT work and results in Misplaced \omit. error.  \documentclass{article} \usepackage{xparse}  \newcommand{\MulticolumnA}[3]{&amp;\multicolumn{#1}{#2}{#3}} \newcommand{\MulticolumnB}[3]{ \multicolumn{#1}{#2}{#3}}  \NewDocumentCommand{\MulticolumnX}{m m m}{&amp;\multicolumn{#1}{#2}{#3}} \NewDocumentCommand{\MulticolumnY}{m m m}{ \multicolumn{#1}{#2}{#3}}  \begin{document} \[ \begin{tabular}{lllllll}     {a} \MulticolumnA{4}{l}{A-abcdefghijkli}\\     {a}&amp;\MulticolumnB{4}{l}{B-abcdefghijkli}\\     {a} \MulticolumnX{4}{l}{X-abcdefghijkli}\\     %{a}&amp;\MulticolumnY{4}{l}{Y-abcdefghijkli}\\     {col1}&amp;col2&amp;{col3}&amp;{col4}&amp;{col5}\\ \end{tabular} \] \end{document}   Above compiles as is, but does not compile if the one line is uncommented. I'm struggling to understand the difference between the standard error and the standard deviation. How are they different and why do you need to measure the standard error? Compute $e^{e^z}$, where z is a complex number I am self-studying the MAT 67 linear algebra course and I got stuck at a problem in Chapter 2:     Compute the real and imaginary parts of $e^{e^z}$ for $z$ $\in$ $\Bbb C$.   I tried to expand it using Euler's formula but it seemed endless. Any help? Which is correct?     Everyone were convinced that he would go to the game.   Everyone was convinced that he would go to the game.   I think it's "was", because "everyone" is singular, but I just wanted to check. What does protection from [quality] do? Example 1) Let's say I have some random creature with protection from white, and my opponent plays , a white card with the effect "Destroy all creatures." Can my creature with protection from white be destroyed by a white card that isn't actually targeting it specifically?  Example 2) I was playing a match with a friend where I had  on the field against his 3 zombies. Is he able to declare his zombies as blockers even though Elite Inquisitor has "protection" from zombies?  If he can declare them as blockers, does protection mean that no damage is dealt by the zombies to  Elite Inquisitor? How do I remap certain keys or devices? i want to add watermark on some videos but problem is because image in some videos its too small and in some videos its too big, (i think it depends on input link resulution)   so all my videos have output '640:360' so how can i make watermark image to be same in all videos not on some videos smaller in some bigger   ffmpeg -i "link" -i "/var/www/logo/logo1.png" -filter_complex 'overlay=10:10' -vcodec h264 -crf 25 -preset superfast -maxrate 600k -bufsize 600k -aspect '640:360' -s '640:360' .... I went to the doctor's I have run across such a sentence:     Yesterday I was ill, so I went to the doctor's.   What is the function of possessive here, that is doctor's? I've believed for a long time that every Lie group can be decomposed as the semidirect product of a connected Lie group and a discrete Lie group. However, in , it is mentioned that this is not true, and that there exist obstructions to this decomposition. Unfortunately, the level of complexity in the answers goes a bit over my head.  This type of decomposition is also addressed in .  With this loss of faith in my intuition, I have three questions:   Is it true that Lie groups do not necessarily decompose into the semidirect product of a connected group and a discrete group? If this decomposition doesn't always work, then is there a particularly nice argument as to why it doesn't? If this decomposition doesn't always work, then is there a nice example I can use to convince myself that my intuition is wrong?   Edit: As much as I love Qiaochu Yuan's answer, which is thorough and (as usual) a role model among Stack Exchange answers, this is not what I'm looking for. I'm aware of the general extension problem, and that not every short exact sequence splits, but my intuition has led me to think that each Lie group can be decomposed this way. I will certainly play around with his outline for a construction, but I would much prefer a more concrete answer. Once again, thank you!  Edit: As of yet, playing with the construction suggested by Qiaochu hasn't yielded anything interesting. This question is still open to answers! How to add a directory to the PATH? Finding parenthesis via regular expression Why does resistivity increase with temperature?  The explanations I have heard so far are that increasing temperature increases vibrations in the lattice structure resulting in the number of collisions increasing.  But the vibrations from thermal energy are random, so around half of the vibrations would result in the atoms moving out of the electrons way and half would result in atoms moving into the way of the electrons.  And since half of the vibrations result in increasing the drift speed and half reduce it, shouldn't the average drift speed remain the same? My awk program to change spaces into tabs doesn't work How to write a shell script which uses awk to read in the data file students.txt and output the data in the tabbed format as shown:  Surname Forename MSc Stream Date of Birth Smith John IT 15.01.1986 Taylor Susan IT 04.05.1987 Thomas Steve MIT 19.04.1986    Do not worry if tabbed columns don’t line up. The distance between each of (Surname, Forename, MSc Stream and Date of Birth) column is one tab.   Question:  Why this bellow code doesn't work for me?  awk 'BEGIN {IFS=" "} {OFS="\t"} {print $1,$2,$3,$4}' students.txt Is it possible to have several different views of one scene and set them as named "presets"? Prove $(x+y) \text{ mod } n = ((x \text{ mod } n)+(y \text{ mod } n)) \text{ mod } n,\,$ and product analog For all $n \in \mathbb{N}$, $n &gt; 1$ and $x,y \in \mathbb{Z}$ prove that      \begin{equation}   (x+y) \text{ mod } n   = ((x \text{ mod } n)+(y \text{ mod } n))\text{ mod } n. \end{equation}   Would this be a proof if I say:  Let $x = x' \text{ mod } n$ and let $y=y' \text{ mod } n$. Then  \begin{equation}   x+y = x'+y' \text{ mod } n. \end{equation}  Now, if we look at the current thing we want prove, this will follow:  \begin{equation}   x+y \text { mod } n = (x \text{ mod } n + y \text{ mod } n) \text{ mod } n. \end{equation}    I'm not sure if this is allowed or will count as a "proof" at all. Maybe you can show me some other ways of doing this, more precise ones? Consider a text file with the following entries:  aaa bbb ccc ddd eee fff ggg hhh iii   Given a pattern (e.g. fff), I would like to grep the file above to get in the output:  all_lines except (pattern_matching_lines  U (B lines_before) U (A lines_after))   For example, if B = 2 and A = 1, the output with pattern = fff should be:  aaa bbb ccc hhh iii   How can I do this with grep or other command line tools?    Note, when I try:  grep -v 'fff'  -A1 -B2 file.txt   I don't get what I want. I instead get:  aaa bbb ccc ddd eee fff -- -- fff ggg hhh iii Unexpected voltage with switch turned off I recently installed Ubuntu 17.10, and when I tried to set my keyboard layout to change with alt+shift, I hit a . There is  which works, but then it creates an unwanted behaviour on Firefox (perhaps other programs as well).   After setting alt+shift through gnome-tweak-tool as the combination to change language, whenever this combination is pressed within Firefox, it triggers a toggle that Firefox uses to show/hide the Menu Bar (with File/Edit/View etc.), and 'focus' is taken away from wherever the cursor was.   It's very frustrating, because one has to go and click again at the cursor.  The only solution I found was to permanently enable Menu Bar in Firefox because then alt doesn't do anything and I can use it to change languages. But I don't want to have Menu Bar on top always.  I hope you can understand what I'm trying to explain.  Any thoughts? Is it possible to prevent an NSURLRequest from caching data or remove cached data following a request? On iPhone, I perform a HTTP request using NSURLRequest for a chunk of data. Object allocation spikes and I assign the data accordingly. When I finish with the data, I free it up accordingly - however instruments doesn't show any data to have been freed!  My theory is that by default HTTP requests are cached, however - I don't want my iPhone app to cache this data.   Is there a way to clear this cache after a request or prevent any data from being cached in the first place?  I've tried using all the cache policies documented a little like below:  NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]]; theRequest.cachePolicy = NSURLRequestReloadIgnoringLocalCacheData;   but nothing seems to free up the memory!