In LaTeX, there are two epsilons: \varepsilon and \epsilon.    When I see the second one used in mathematics texts, I consider it a typo, because the first one corresponds to what is used in the majority of texts but also what is used when writing maths by hand. By personal taste, I prefer the first one and consider it the correct version.   Be that as it may, whichever is the correct one, there seems to be no need to have two. Hence my question:   Why are there two versions or epsilons? Why does the command \epsilon not get compile into the first version?  \documentclass{article} \usepackage{amssymb}  \begin{document} \begin{tabular}{ll} \texttt{\textbackslash{}varepsilon}     &amp; \(\varepsilon\)   \\ \texttt{\textbackslash{}epsilon}        &amp;\(\epsilon\)            \end{tabular} \end{document}
I cannot remember anyone writing the letter epsilon in any other way than \varepsilon in any math class; but in LaTeX \epsilon and \varepsilon are different symbols. Do any of you know why there are two different symbols? (I.e. if \epsilon is the correct way to write the letter epsilon, why aren't mathematicians using it, and when is, according to the standards today, the correct situation to use each of the symbols?)
Read Post Data submitted to ASP.Net Form I have a working login form in an asp.net application.  Standard stuff with a username and password text box and a button to process the login.  Works fine.  I have a new requirement to allow the user to input the username and password from a separate plain html page that is not a part of my asp.net application.  I plan on achieving this using standard html - form, input, submit button etc.  The form action will be the URL of my asp.net login page and its method will be POST.    What I want to do in the C# code behind page of the asp.net login form, presumably in the Page_Load event, is to check if the request for the page contains a username and password value being passed in.  If it does then I need to read those values and process the login as if someone had clicked the login button on the asp.net page.  If not then I will display the login form as usual.    How do I check for the existence of, and read, the username and password values in the request for my page. Where does tidal energy come from? Kind of an odd, random question that popped into my head. Tidal energy - earth's ocean movement, volcanism on some of Jupiter's moons, etc. - obviously comes from the gravitational interaction between large bodies. On earth the interactions with the moon are pulling water around the surface, creating some amount of heat due to friction, etc.   My question is, where does that energy come from exactly? More specifically, what potential energy source is getting depleted to do that work? Is the earth minutely slowing down in its spin - or are the orbits of earth and the moon subtly altered over time by the counteractive movement and friction of liquids and gasses? If $\sin(a)\sin(b)\sin(c)+\cos(a)\cos(b)=1$ then find the value of $\sin(c)$ He who must not be named? (aka Anyone can ping everyone in chat) For some or other reason, typing @ᔕᖺᘎᕊ in a chat room pings everyone who's been in that chat room for the last 7 days...    Seems to work in all chat rooms (I only tested 2 as I don't want to upset too many people...)  How should we proceed? How to set system-wide environment variables on OS X Mavericks Stack Exchange iOS app crashes on start Upon clicking on SE icon, blue (starting) screen appears and then I am back to home screen, SE app simply won't start. This kind of behaviour never happened before (on any other app). I tried to remove it from &quot;task manager&quot;, reinstalling and logging back in; neither did work. In Settings -&gt; Stack Exchange -&gt; Notices I found a log message:  FILE DOESN'T EXIST, WILL CREATE: users/dev/buildagent/work/{id}/pods/target support files/pods/pods-ack...plist   App Version: 1.4.0 Device: iPhone7,2 OS Version: Version 9.1 (Build 13B143)   TLDR: app starts when cellphone has no internet access. I just noticed when I am on 3G (cellular internet) it crashes ASAP, but when I am on wifi that has no internet (for LAN etc.) app starts normally but no new content, when I turn off WiFi and iPhone switches to cellular; app crashes. Note: I turn off WiFi using control center - so I never leave the app. Another thing, when I force iPhone to use EDGE (slowest possible internet) app starts, and crashes after 5 seconds or so. I assume when app downloads some data from server.  Known workaround (works for me too)  I found a workaround: turn on Airplane Mode, launch the app, then turn Airplane Mode off. – NobodyNada Install MySQLdb (for python) as non-compressed egg How does one go about proving that the function $x \sin x$ is not uniformly continuous on the set of real numbers ?  Any method that uses the sequential criterion for discontinuity would be preferred.  Thanks in advance ! I wanted to add classpath to my JDK. While searching a way to do it I noticed everyone open .profile file using terminal. But when I want to open and edit it with a text editor I couldn't see that file in Home folder.  Can someone tell me why is this. And also if possible how can I access .profile in home folder the GUI way. Microsoft has steadily improved its operating cash flows in the past three years. Microsoft has steadily improved its operating cash flows in the last three years. Microsoft has steadily improved its operating cash flows for the past three years. Microsoft has steadily improved its operating cash flows for the last three years. Microsoft has steadily improved its operating cash flows for the past three years. (&quot;for&quot; omitted) Microsoft has steadily improved its operating cash flows for the last three years. (&quot;for&quot; omitted) Microsoft has steadily improved its operating cash flows during the past three years. Microsoft has steadily improved its operating cash flows during the last three years. Microsoft has steadily improved its operating cash flows over the past three years. Microsoft has steadily improved its operating cash flows over the last three years.  Which of them are idiomatic and preferred? Are they interchangeable? LaTeX Error: Option clash for package xcolor How to select an element inside "this" in jQuery? Where were the capital ships and bombers? When I´m in a secure part of a web-site I´m developing (entering a specific page or folder using https), the relative links to the normal pages are automatically converted to https as well. Is there a way to tell an &lt;a&gt; tag to always use the http protocol instead of the https protocol (or the other way around)? I know it´s easy using the complete link ( or ), but I would like it to work with relative links (index.html, ../index.html, etc.). I am attempting to install Ubuntu on a box which was previously running Windows 7.  I have also experienced the dreaded "Unable to install GRUB" error.  I am not attempting to dual boot. I have previously run a Windows boot disk and removed all existing partitions.  If I run the Ubuntu 12.04 install CD and click install after the config screens, I get the error   Executing 'grub-install /dev/sda' failed. This is a fatal error. (It is the same error as this question: )  All the questions I've read while looking for a solution are related to dual boot.  I'm not interested in dual boot, I'm after a clean out the box Ubuntu install. How can I achieve this?  (For my sanity, please use very simple instructions when responding. I don't claim to have any talent either for linux or as a sysadmin)    Additional details copied from comments dated: 2012-05-29 ~15:19Z  After booting from the CD, clicking Try Ubuntu, and then sudo fdisk /dev/sda I get fdisk: unable to seek on /dev/sda: Invalid argument  sudo fdisk /dev/sdb gives   Device contains neither a valid DOS partiion table, nor Sun, SGI or OSF disklabel.  Building a new DOS disklabel with disk identifier 0x15228d1d.  Changes will remain in memory only until you decide to write them.  After that of course, the previous content won't be recoverable.  Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite).  Command (m for help):   I should add the Live CD desktop is graphically bad. I've got missing parts of programs and the terminal occasionally reflects to the bottom of the screen. But I can't imagine this is related. A problem about Vandemonde matrix Is it correct to say "What was your name?"? The reason I am asking this is, generally the name of the person will not change. One should say "What is your name?" I just came onto a project with a pretty huge code base.   I'm mostly dealing with C++ and a lot of the code they write uses double negation for their boolean logic.    if (!!variable &amp;&amp; (!!api.lookup("some-string"))) {        do_some_stuff();  }                                      I know these guys are intelligent programmers, it's obvious they aren't doing this by accident.   I'm no seasoned C++ expert, my only guess at why they are doing this is that they want to make absolutely positive that the value being evaluated is the actual boolean representation. So they negate it, then negate that again to get it back to its actual boolean value.   Is this correct, or am I missing something? Would this look natural:     StackExchange is a helluva site! I found out about this site at Facebook.    Or should we use the preposition on:     StackExchange is a helluva site! I found out about this site on Facebook.    Or are both okay?   (Inspired by a ) Login not redirecting back to page where login link was clicked if account created