Hi i am having a problem making a custom tag for this equation  \begin{equation*}\label{eq:3}         C_1 = \theta \left(Y_1^L -T_1+\frac{1}{1+r}(Y_2^L+T_2)+V_1\right) \tag(3)     \end{equation*}   I want to refer to an equation from a book (as part of my class) which i called equation 3. But i simply can't change it without getting a lot of syntax errors.  I have tryed different things form the forum, but so far without luck.  Hope you can help.
I would like to label an equation with an arbitrary symbol, rather than a number, or letter.  Is this possible?
Is it okay to use my US visa after a name change? Is it possible to schedule my laptop to mute and unmute at a specific time? I always used to wake up to my favorite radio station on my alarm clock. However, I have moved and can no longer get that radio station over the air. To solve this problem, I would like to stream the station on my laptop, but have it muted overnight, then set it to unmute at a specific time in the morning, so that it will act as an alarm clock. Is there a way to schedule my laptop (Windows 7 64-bit) to unmute at a specific time? Monty hall problem extended. I just learned about the Monty Hall problem and found it quite amazing. So I thought about extending the problem a bit to understand more about it. In this modification of the Monty Hall Problem, instead of three doors, we have four (or maybe $n$) doors, one with a car and the other three (or $n-1$) with a goat each (I want the car).  We need to choose any one of the doors. After we have chosen the door, Monty deliberately reveals one of the doors that has a goat and asks us if we wish to change our choice.  So should we switch the door we have chosen, or does it not matter if we switch or stay with our choice?  It would be even better if we knew the probability of winning upon switching given that Monty opens $k$ doors. Does this email mean that I have been granted the visa? I have a windows forms app with a textbox control that I want to only accept integer values. In the past I've done this kind of validation by overloading the KeyPress event and just removing characters which didn't fit the specification. I've looked at the MaskedTextBox control but I'd like a more general solution that could work with perhaps a regular expression, or depend on the values of other controls.  Ideally this would behave such that pressing a non numeric character would either produce no result or immediately provide the user with feedback about the invalid character. In my program I have one array with 25 double values 0.04 When I try to sum these values in a loop I get following results:  0.0 + 0.04 = 0.04 0.04 + 0.04 = 0.08 0.08 + 0.04 = 0.12 0.12 + 0.04 = 0.16 0.16 + 0.04 = 0.2 0.2 + 0.04 = 0.24000000000000002 0.24000000000000002 + 0.04 = 0.28 0.28 + 0.04 = 0.32 0.32 + 0.04 = 0.36 0.36 + 0.04 = 0.39999999999999997 0.39999999999999997 + 0.04 = 0.43999999999999995 0.43999999999999995 + 0.04 = 0.4799999999999999 0.4799999999999999 + 0.04 = 0.5199999999999999 0.5199999999999999 + 0.04 = 0.5599999999999999 0.5599999999999999 + 0.04 = 0.6 0.6 + 0.04 = 0.64 0.64 + 0.04 = 0.68 0.68 + 0.04 = 0.7200000000000001 0.7200000000000001 + 0.04 = 0.7600000000000001 0.7600000000000001 + 0.04 = 0.8000000000000002 0.8000000000000002 + 0.04 = 0.8400000000000002 0.8400000000000002 + 0.04 = 0.8800000000000002 0.8800000000000002 + 0.04 = 0.9200000000000003 0.9200000000000003 + 0.04 = 0.9600000000000003   Why on earth could that happen?! What a pluperfect a##hole Picklist dependent on 2 controlling picklist Why and how is the speed of light in vacuum constant, i.e., independent of reference frame? Collection of short stories; in one a spy attempts to escape detection on Mars's moon by moving faster than the spaceship can scan This is an unproven proposition I've come across in multiple places.   Suppose $A$ is a commutative Noetherian ring, and $S$ a multiplicative subset of $A$. Then $S^{-1}A$ is Noetherian.  Why is this? I thought about taking some chain of submodules $$ S^{-1}M_1\subset S^{-1}M_2\subset\cdots $$ and pulling back to a chain  $$ M_1\subset M_2\subset\cdots $$ of submodules of $A$ which must eventually stablize. Is there more to it than this? I kind of wary of assuming all submodules of $S^{-1}A$ have form $S^{-1}M$ for $M\leq A$. I installed an alpha or beta, am I up to date with the final release if I keep upgrading? I'm sorry if this question goes against the meta for posting questions - I attached all the "beware, this is a soft-question" tags I could.  This is a question I've been asking myself now for some time. In most areas, there's a "cut off age" to be good at something. For example, you're not going to make the NHL if you start playing hockey at 20. It just won't happen.  So my question then, how late is too late to start studying math and make a career out of it? By "start studying math" I mean, to really try to understand and comprehend the material (as opposed to just being able to do well in a formal, intuitional environment).   I don't mean this from a "do what you love, its not too late" motivational perspective. I mean this from a purely biological perspective; at approximately what age has your brain's capacity to learn effectively and be influenced by your learning stop? When does the biological clock for learning new math run out?  My reasoning for asking this question is (for those who care): I love math. Really I do. But , having spent the first 21 years of my life in sports/video games/obtaining a degree in a scientific field which I care nothing of/etc, despite all my best attempts at trying to learn math, am I just too late starting to ever actually be good enough at it to make it a career? I've almost completed my second degree (in Math), but find that in many cases, despite how I look at a problem, I lack the intuition to comprehend it. I'm going to single him out (sorry), only as an example, but Qiaochu Yuan is my age.   Note 1: If this question isn't a suitable post, I won't be offended at all if you vote to close - I know this question borders what's acceptable to ask.  Note 2: Thanks to everyone for reading and taking the time for the great responses. Really appreciate it! Incorrect plot using pgfplots (trigonometric functions like cos, sin and tan) I'm trying to plot a function with pgfplots for LaTeX. Unfortunately, pgfplots plots the function incorrectly.  Here is the LaTeX code I use:  \begin{figure}[H] \centering \begin{tikzpicture}     \begin{axis}[xlabel=Gameplays,ylabel=Rating]         \addplot+[gray,domain=1:30]         {0.5 + 0.5 * ((atan(x) * 2 / pi)^11.79)};     \end{axis} \end{tikzpicture} \caption{Omzetten van aantal gameplays tot impliciete rating} \label{fig:omzetten_impliciete_ratings} \end{figure}   Here is how the function should look like:     This is how it is plotted:    Does anyone know what I do wrong?  Thanks in advance! Is there a filesystem that is "friendly" to both windows and Linux? C programming: How to program for Unicode? Where can I get a Thunderbolt hub or splitter? Apple has just announced the new MacBook Airs, Mac mini, and Thunderbolt display. One of the features of the Thunderbolt display that caught my eye was its ability to daisy-chain two displays together from one Thunderbolt port (on a MacBook Pro).  I already have two 24" monitors and I don't feel like paying for two £900 displays. I worked out that all I need is a Thunderbolt hub/splitter so that I can plug the two cables that emerge into mini DisplayPort-to-DVI adapters.  Does anyone know of any Thunderbolt hubs or splitters? Or does anyone know of an alternative method? "If $1/a + 1/b = 1 /c$ where $a, b, c$ are positive integers with no common factor, $(a + b)$ is the square of an integer" If $1/a  +  1/b  =  1 /c$   where $a, b, c$ are positive integers with no common factor, $(a + b)$ is the square of an integer.  I found this question in RMO 1992 paper !  Can anyone help me to prove this ?  May be it's too easy and simple . But , I'm just novice in number theory ! Dictionary for TeXstudio: “No dictionary Available” I have trouble spell checking my document in TeXstudio. When I press spellcheck, I get the error No dictionary Available. Am I supposed to install a dictionary separately? How? Any suggestion? How to get week number in Python?