At the moment I write macros without breaking them up, like so:  \NewDocumentCommand{\HC}{ o }{\IfNoValueTF{#1} {\emph{HC}\xspace}{\emph{HC}, p.#1\xspace}}   This obviously gets pretty hard to follow once things get longer. Examples on this site are always broken into separate lines, using % at the end of each line. I have never been sure what the rules are for how to do this effectively, or what the practice of arranging code in this way is. I feel that I am falling into a very bad habit by ignoring this. Is there a guide to this anywhere on this site or elsewhere, or is it just personal preference?
I have been using LaTeX for a long time now, but still all my document files look a bit messy. Now I want to get rid of this bad habit and get some order into my code.  That is why I am wondering whether there are any coding style guidelines for LaTeX. Not necessarily anything official. It could for example make recommendations on how to format your code with respect to:   Setting comments in the text/preamble Whether to highlight sections/subsections etc. by some comments How to indent environements How to organize your preamble to make it readable etc.   If nothing as such exists (yet), it would be great if you could just post how you do it if you think your code looks rather nice.
How to derive this binomial identity? register_nav_menus() won't register menus Please help with menu registeration:  I have followed this guide (http://codex.wordpress.org/Navigation_Menus) step by step.  Added the following code to functions.php:  function register_my_menus() {   register_nav_menus(     array('header-menu' =&gt; __( 'Header Menu' ) )   ); }  add_action( 'init', 'register_my_menus' );   But the guide says that this will make the menu appear in the Appearance -> Menus admin screen in the "Theme Locations" box as "Header Menu".  When I go to Appearance -> Menus everything is greyed out and there is no option of "Theme Locations" Java Access Denied How do I free up more space in /boot? My /boot partition is nearly full and I get a warning every time I reboot my system. I already deleted old kernel packages (linux-headers...), actually I did that to install a newer kernel version that came with the automatic updates.  After installing that new version, the partition is nearly full again. So what else can I delete? Are there some other files associated to the old kernel images?  Here is a list of files that are on my /boot partition:  :~$ ls /boot/ abi-2.6.31-21-generic         lost+found abi-2.6.32-25-generic         memtest86+.bin abi-2.6.38-10-generic         memtest86+_multiboot.bin abi-2.6.38-11-generic         System.map-2.6.31-21-generic abi-2.6.38-12-generic         System.map-2.6.32-25-generic abi-2.6.38-8-generic          System.map-2.6.38-10-generic abi-3.0.0-12-generic          System.map-2.6.38-11-generic abi-3.0.0-13-generic          System.map-2.6.38-12-generic abi-3.0.0-14-generic          System.map-2.6.38-8-generic boot                          System.map-3.0.0-12-generic config-2.6.31-21-generic      System.map-3.0.0-13-generic config-2.6.32-25-generic      System.map-3.0.0-14-generic config-2.6.38-10-generic      vmcoreinfo-2.6.31-21-generic config-2.6.38-11-generic      vmcoreinfo-2.6.32-25-generic config-2.6.38-12-generic      vmcoreinfo-2.6.38-10-generic config-2.6.38-8-generic       vmcoreinfo-2.6.38-11-generic config-3.0.0-12-generic       vmcoreinfo-2.6.38-12-generic config-3.0.0-13-generic       vmcoreinfo-2.6.38-8-generic config-3.0.0-14-generic       vmcoreinfo-3.0.0-12-generic extlinux                      vmcoreinfo-3.0.0-13-generic grub                          vmcoreinfo-3.0.0-14-generic initrd.img-2.6.31-21-generic  vmlinuz-2.6.31-21-generic initrd.img-2.6.32-25-generic  vmlinuz-2.6.32-25-generic initrd.img-2.6.38-10-generic  vmlinuz-2.6.38-10-generic initrd.img-2.6.38-11-generic  vmlinuz-2.6.38-11-generic initrd.img-2.6.38-12-generic  vmlinuz-2.6.38-12-generic initrd.img-2.6.38-8-generic   vmlinuz-2.6.38-8-generic initrd.img-3.0.0-12-generic   vmlinuz-3.0.0-12-generic initrd.img-3.0.0-13-generic   vmlinuz-3.0.0-13-generic initrd.img-3.0.0-14-generic   vmlinuz-3.0.0-14-generic   Currently, I'm using the 3.0.0-14-generic kernel. Why can't I find a USB-C hub with multiple USB-C ports? My computer only has one USB-C port and I want to connect multiple USB-C devices to it.  I have trawled through Amazon but am amazed that I cannot find a single one. There are many hubs that have USB 3.1 USB-A ports but not USB-C ones.  Is there a limitation in the spec that prevents this being possible? Let $\theta \in R^{n}$. The Fisher Information Matrix is defined as:  $$I(\theta)_{i,j} = -E\left[\frac{\partial^{2} \log(f(X|\theta))}{\partial \theta_{i} \partial \theta_{j}}\bigg|\theta\right]$$  How can I prove the Fisher Information Matrix is positive semidefinite? Can I have dynamic custom variables in Word? I'm basically trying to create a variable in a document, let's say the name of a person, so that I can change the value in a single place and it updates through the whole document.  I've been reading about Fields and about a DOCVARIABLE, but I can't find where to edit the value (right clic didn't show an "edit" option). I'm using Word 2011 for Mac (that's what we have at work right now) so I'm wondering whether this version of Word is just not intuitive, or I cannot have variables like that in Word and I'm misinterpreting the documentation.  This is what I intend to do:  Hello, my name is PERSON_NAME, I have PERSON_AGE years old.   You get the idea.  PS: We actually want to modify the variables' values from our app, rather than from Word itself, kind of like injecting values to a .*docx file. I recently tried to use QGIS and I wondered if you can convert a draft ArcGIS map (*.mxd file) into a QGIS project (*.qgs file).   This would avoid thematize the entire project. I recently submitted an application to the AppExchange, only to have it not pass the security check due to "Insecure Storage of Sensitive Data Vulnerability." The problem is that my app accesses an external API, for which it has its own API Secret and API Key. These are static, and specific to the Salesforce App- they will be the same for all users, all installations, etc.  Perhaps stupidly, I stored them as private properties of the class that uses them.  private static String apiSecret = 'superS3|&lt;R37'; private static String apiKey = 'sameHerebutdifferent';   It is a Managed app, so users cannot see them. As such, I am puzzled as to 1. why this is insecure and 2. how better to store these values, given that we are apparently operating under the assumption that having them in the text of the class itself is insecure. I apologize for the subjective "best" keyword.  My friend and I have started creation of a 2D adventure game. It will be top-down in the style of pokemon or zelda (just the perspective). We have been discussing methods of creating a large world-map that the player can traverse without straining the memory capabilities of our machine.  Our first impulse was to create a large map and a circle around the player in which content will be loaded. We figured this won't hold for long and decided to partition the map into sections. First we had four large sections, but realized we could simply break it down into many tiny sections.  I played some Zelda from the SNES and saw that, during the shift of a map, the content could be loaded just then. What I mean is, instead of just checking a rectangular area for data to load, we simply section the map into many tiny chunks that load and de-load data as we move from map-portion to map-portion.  Today, he told me he wanted to create a simply 2D array map[WIDTH][HEIGHT] that contains data about every grid in the game and is a constant save-to-disk operation for data that we don't need.  I'm not sure about these ideas and thought that I might as it here. Any links, resources or tutorials on the subject would be greatly appreciated as well as direct answers to our question on how to do it efficiently. Division algorithm for polynomials in R[x], where R is a commutative ring with unity. Is there a division algorithm for polynomials in R[x], where R is a commutative ring with unity?    All the algebra books I read mention division algorithm for polynomials in F[x], where F is a field. Since the leading coefficient of a non zero polynomial in R[x] is not necessarily invertible, I find it difficult to proceed the same way we do for polynomials in F[x].  Can I get some help? Let $x&gt;0$, $y&gt;0$ and $z&gt;0$. Show that   $$x^3y+y^3z+z^3x\ge xyz(x+y+z).$$   I known we can't WLOG: $x\ge y\ge z$, if this, I can use rearrangement inequality, But other I can't it. Thanks? How to integrate this nasty integral How do you go about integrating this? For context purposes, $s$ is a constant and $n$ is just the variable we need to integrate for. If needed, a number can be substituted for $s$, but I would like it without preferably.   $$\int\frac{s\sqrt{3}\sqrt{s^2-2ns\sqrt{7}+4n^2}}{2s^2-4ns\sqrt{7}+8n^2}dn$$ Why is document.write considered a "bad practice"? How to redirect output of a running program to /dev/null I know that in order to suppress the output of a program I can redirect it to /dev/null, for example to hide all error and warning messages from chromium I can start the program like this  chromium-browser 2&gt; /dev/null &amp;   However, if I happen to forget about the error messages and type  chromium-browser &amp;   (which is quite annoying when they appear in the middle of a command) I don't know what to do except for stopping the application and starting it again properly.  Can I somehow redirect error output without restarting the application? What is the difference between a deep copy and a shallow copy? Environment variables are not passed to sub scripts while running on crontab I was trying to run one of the scripts (for example, wrapper.sh) which internally executes other scripts using crontab. It works fine without any issues.  When I have created a environment file (which stores the passwords-DB and paths) and trying to execute the main script (wrapper.sh) the cron entry doesn't work on those scripts which are called internally in the wrapper.  NOTE: I tried changing PATH, added env file location before the script in cron but it still didn't work:  9 9 * * * . /$SOMEPATH/some.env; /$SOMEPATH/wrapper.sh   The environment script and wrapper.sh are in same path. when the cron runs it passes the env variables to wrapper but not to the scripts which are called internally in wrapper. Also a mail is received on /var/mail/$user saying the env file as "No such file or Directory". I've gone through many posts but couldn't figure out the resolution. What are preimage resistance and collision resistance, and how can the lack thereof be exploited? What is "preimage resistance", and how can the lack thereof be exploited? How is this different from collision resistance, and are there any known preimage attacks that would be considered feasible? Can I dump my non-Retina Images for a iOS7 only app? No non-trivial clopen sets in $\mathbb{R}$? How to give a direct proof? How to give a direct proof of the following result?     Let $A$ be a subset of $\mathbb{R}$ such that $A$ is both open and closed. Then $A$ is either empty or all of $\mathbb{R}$?   My work:   If $A$ is not empty, let $u \in A$. Then there is some open interval $(a,b)$ such that $$u \in (a,b) \subset A.$$  Now if $\mathbb{R} - A$ is not empty either, then let $v \in \mathbb{R} - A$. Then there is some open interval $(c,d)$ such that  $$v \in (c,d) \subset \mathbb{R} - A.$$  Suppose that $u &lt; v$.   Since $$\emptyset \subset (a,b) \cap (c,d) \subset A \cap (\mathbb{R} - A) = \emptyset,$$ we must have $$(a,b) \cap (c,d) = \emptyset.$$ So we can conlclude that $$b \leq c.$$ But $b \in A$ and $c \in \mathbb{R} - A$. So we must have $$b &lt; c.$$  What next? Can anybody here please help complete the proof from here on?  An edit based on a comment by Marc Paul:   Let us assume that the set $A$ is a non-trivial clopen set in $\mathbb{R}$. Let us define a function $f \colon \mathbb{R} \to \mathbb{R}$ as follows:  $$f(x) \colon= \begin{cases} 1 \ \mbox{ for } \ x \in A; \\ 0 \ \mbox{ for } \ x \in \mathbb{R} - A. \end{cases}$$   Let $V$ be an open set in the range space $\mathbb{R}$. We show that the inverse image set $f^{-1}(V)$ is open in the domain space $\mathbb{R}$.   The following cases arise:   If $0, 1 \in V$, then $f^{-1}(V) = \mathbb{R}$.   If $0 \in V$ but $1 \not\in V$, then $f^{-1}(V) = \mathbb{R} - A$.   If $1 \in V$ but $0 \not\in V$, then $f^{-1}(V) = A$.   And, if $0 \not\in V$ and $1 \not\in V$, then $f^{-1}(V) = \emptyset$.   Thus, $f^{-1}(V)$ is open in the domain space $\mathbb{R}$.   Hence the function $f$ is continuous.   What next? How does this lead to our desired conclusion?   [Yet another edit, again based on valuable comments from Marc Paul: ]  So if both $A$ and $\mathbb{R} - A$ were non-empty, then let's suppose $a \in A$ and $b \in \mathbb{R} - A$, and we can assume without any loss of generality that $a &lt; b$.   Then $f(a) = 1$ and $f(b) = 0$. So by the intermediate value theorem there is a real number $c \in (a,b)$ such that $f(c) = 1/2$, which is a contradiction because the image set of $f$ does not contain $1/2$.