I want to learn more about the -n or -z option  in IF condition, I tried: man if   man condition  don't know where I can getto the  the manpage of 'IF condition'.
I would like to know if there is any man page documenting the construction of the most basic script commands like if/then/else, while, for each, and all the relative switches, like -eq, -e, -ge, and so on.
How can I prevent inline math formulas from overflowing into the margin? When I compile my document in LaTeX, some formulas in the document in math mode, between $ $, go into the right margin area beyond all the text.  Is there a way to fix this aesthetic problem? Another question I am struggling with:  Let $f:\mathbb{R} \rightarrow \mathbb{R}$ be defined in a neighborhood of $a$ (except maybe $a$ itself) and suppose that, $\lim_{x \rightarrow a}\left(f(x)+\dfrac{1}{\left|f(x)\right|}\right)=0$. Find $\lim_{x \rightarrow a}f(x)$, and prove by definition, that this is indeed the limit.    Thank you all for your answers!!  But.. How can I prove by definition that this is indeed the limit? take $\epsilon&gt;0$, I have to show that there exists a $\delta&gt;0$ such that, $|x-a| \leq \delta$ implies $|f(x)+1| \leq \epsilon$. now, I do know that there exists an $\delta_1&gt;0$, such that $|f(x)+\frac{1}{|f(x)|}|&lt; \epsilon$.Or, $\frac{\epsilon}{k}$ for some constant $k$ But, how can I continue from there? Calculate the radius of a circle given the chord length and height of a segment I have a (circular) segment of known height and known chord length. Is is possible to determine the radius of the circle?  Any help much appreciated. Can a fundamentally deceptive character work? This question is in the spirit of another . I would like to explore a style of role-playing in DnD (specifically 3.5e) that may be slightly different from how characters usually work. The question aims to answer if and how such a character can work and be played for everyone's amusement. I am still relatively new to the game, so please forgive me if this question is naive. Probably people have tried before and discarded the idea.  Character concept The character is supposed to be deceptive, on both the character and the player level. He will thrive to achieve some higher goal that is different to the party's, but not in an open way. He will play along and work for the party's interest, but wait for his moment (ideally towards the end of the campaign) to strike. As such an evil religious fanatic would be ideal, who works towards achieving the goals of his deity by deceiving his party members, gaining their trust and acquiring resources together with them, but when given the choice would take the powerful magical item and bugger off with it. Motivation and Concerns The main motivation is to bring some diversity to the usual scheme. People tend to play funny characters and there is usually (at least in our games) happy peace in the party with the only dispute being about who gets the loot. I feel a character like the one suggested would make things more interesting since people can't take their party members for granted anymore. The concern is of course that it might not be very fun for the party to have their plans destroyed by one member of the party playing an &quot;extra cool&quot; character. I think done well, it could still be fun for the other players though, which is why the rest of the question will be about how to do it. How? First of all the DM should probably know, maybe he can even build it into his campaign. The exact story details will then depend on the exact setting, but I am sure together with the DM something could be worked out. I am mainly interested in if it can work and how it could be fun. Creating A Bootable USB Of Windows 8.1 On OS X? Reasons for wanting create such a usb include:   PC is unbootable and you want to prepare a bootable USB using the ISO file that you have on your external hard drive. to install Windows 8.1 on Mac without Boot Camp.   What are the necessary steps to create such a Windows 8.1 bootable usb on a Mac ? I have an iPhone with 100+ notes that I've collected over the last ten years (thanks to migrating from my PalmPilot). I realize that I can now synchronise these with Gmail, but that doesn't allow me to edit them from my computer. I'd rather switch to use a new app/website combo which allows for online editing of notes, automatic OTA syncing, etc.  It seems like Simplenote and Evernote are two of the better app/sites, as mentioned at  and from this , I think Simplenote is exactly what I'm looking for. The problem is, I can't figure out how to migrate all of my existing notes into whatever new notes app I choose.  How do I migrate my existing Apple iOS Notes into Simplenote or Evernote?  The best workaround I've found so far is to open each note, select all, copy, and create a new note in the iOS app but I'd rather not spend the time and hassle doing this for ~100 notes. How to recover deleted files? Are there any tools, methods, incantations to recover recently deleted files on Ubuntu?  If it makes any difference, I want to recover a  2.x database file. But would be better to have a method/tool that works on any kind of file. double perpendicular symbol (for independence) I found from  that I could use the independence symbol:     \newcommand\independent{\protect\mathpalette{\protect\independenT}{\perp}} \def\independenT#1#2{\mathrel{\rlap{$#1#2$}\mkern2mu{#1#2}}}    I was wondering how this works. Can anybody explain? I don't know the commands mathpalette, rlap, and mkern2mu. Typo in First Posts queue If you go to the First Posts review queue, and if there's an answer in the queue and if you hover with your mouse over "No Action Needed", then you get a tooltip "this answers seems to be valid":  But it should be "this answer seems to be valid". How to Fix Broken Packages? I've seen animated GIF images of screen casts (like the one below) promoted a few times on this site as a way to improve answers.    What toolchain is being used to create these? Is there a program that does this automagically, or are people taking screencasts, converting them into a series of static frames, and then creating the GIF images? Finding $\lim \limits_{x \to 0} \frac{1 - \cos x}{x}$, given $\lim \limits_{x \to 0} \frac{\sin x}{x} = 1$ Does a creature with Lifelink provide lifegain equal to its power, or the defender's toughness? I have recently began playing a deck that has a number of creatures with lifelink in it.  I want to be certain I understand the mechanic and the following question occurred to me.  Which damage total do you use to determine the life gain from lifelink?  I had assumed that if  a 3/3 creature with lifelink was blocked by a 2/2 creature that the life gain total would be 2, the maximum that the blocker can absorb before dying.  This seems to be incorrect, as when I read the example attached to CR 119.4c      [...] attacks with a 3/3 creature with wither and lifelink. It’s blocked by a 2/2 creature, [...]. The damage event starts out as [3 damage is dealt to the 2/2 creature, 2 damage is dealt to the 3/3 creature]   Have I been short changing myself? Today a couple of buffer overflows in NTP were announced , . It looks like updating my system to fix these issues is in order.   How can I find out if they have been fixed in the Ubuntu repositories, such that if I were to run:   sudo apt-get update sudo apt-get upgrade   then the fix would get installed and the vulnerability closed?   Edit: The selected answer specifically addresses the question of how to identify if a given CVE has been fixed or not, "Does Ubuntu generally post timely security updates?"  is certainly related but not identical Can an abstract class have a constructor? Can an abstract class have a constructor?  If so, how can it be used and for what purposes? Continuing in the Visual Studio debugger after an exception occurs When I debug a C# program and I get an exception throwed (either thrown by code OR thrown by the framework), the IDE stops and get me to the corresponding line in my code.  Everything is fine for now.  I then press "F5" to continue. From this moment, it seams like I'm in an infinite loop. The IDE always get me back to the exception line. I have to Shift + F5 (stop debugging/terminate the program) to get out of his.  I talked with some co-workers here and they told me that this happens sometime to them too.  What's happening? What is the best way to detect if a user leaves a web page?  The onunload JavaScript event doesn't work every time (the HTTP request takes longer than the time required to terminate the browser).  Creating one will probably be blocked by current browsers. How do I set my wireless network to be private instead of public? Trying to maintain good security settings on my laptop, I want my home network to be interpreted as private and the university network at school to be interpreted as public. However, my home network is currently showing as public.  Here is what my Network and Sharing Center looks like:    How do I change my home network from public to private on Windows 8 Consumer Preview? What graphics packages are there for creating graphics in LaTeX documents? Perform feature normalization before or within model validation? A common good practice in Machine Learning is to do feature normalization or data standardization of the predictor variables, that's it, center the data substracting the mean and normalize it dividing by the variance (or standard deviation too). For self containment and to my understanding we do this to achieve two main things:   Avoid extra small model weights for the purpose of numerical stability. Ensure quick convergence of optimization algorithms like e.g. Conjugate Gradient so that the large magnitude of one predictor dimension w.r.t. the others doesn't lead to slow convergence.   We usually split the data into training, validation and testing sets. In the literature we usually see that to do feature normalization they take the mean and variance (or standard deviation) over the whole set of predictor variables. The big flaw I see here is that if you do that, you are in fact introducing future information into the training predictor variables namely the future information contained in the mean and variance.  Therefore, I do feature normalization over the training data and save the mean and variance. Then I apply feature normalization to the predictor variables of the validation and test data sets using the training mean and variances. Are there any fundamental flaws with this? can anyone recommend a better alternative?