Let us assume that we have a graph created by a program different from LaTeX (that is not with PStricks or Tikz). I was wandering if it is possible to incorporate mathematical symbols on that graph using a TeX editor.  Thank you.
Recently I have learned how to draw simple stuff with TikZ. I really like it. Now I wonder if it is possible to draw with TikZ on a image. Instead of pasting a image in Illustrator and adding some vectors to point something in the picture I would like to do it using TikZ. Is it possible?   For example, on a picture of a computer (PNG,etc) I would like to draw some arrows and labels saying "Keyboard", "Monitor", etc.
The Definitive C++ Book Guide and List Makeindex error when ! used in \index in align environment See MWE below. The symbol ! in the \index causes an error. This is only the case in align environments (not in equation). So it seems to have to do something with amsmath. If ! is put in an \mbox there is no error. But then of course the font size is not adjusted to subindices. Curiously enough, \index{$C_{K!!}$} (two exclamation marks) doesn't cause any error.    \documentclass{article} \usepackage{amsmath} \usepackage{imakeidx} \makeindex \begin{document} \begin{align} y\index{$C_{K!}$} \end{align} \printindex \end{document}     Any solutions suggested? Why are there scenes that will not render on GPU but will render fine on CPU? I've already tried GPU Rendering and it seem to be twice as fast as the CPU. However I have some situation where tried to render on the GPU, but it doesn't do anything. When I switch to CPU it renders.  I have some fur texture/materials using particle systems. I wonder if that causes the GPU not to render, I'm not really sure. Chat Feature-Request: Thumbs-Up Add an additional form of "I agree" besides starring or pinning (since pinning is restricted to a smaller subset to begin with) or something that we can use to not clog up the right hand star bar.  This is because sometimes you want to say "I agree" but you don't want to star it because ... let's face it, that's not star-worthy, and you don't want to clutter the stream with fifty thousand "like totes for sure, hella right!" because then it becomes one big back-patting party and you lose all semblance of conversation.  So I would propose a fourth "flag" for chat, that allows us to say "I {agree with|like|am of the same opinion as} this comment" and that it would only be useful in the live-chat (and maybe but not really in the transcript) and that it have no other useful semantics (no badges, no list of's [unless the list is of comments you've upthumbed]). How do I connect to a MySQL Database in Python? How do I connect to a MySQL database using a python program? Renaming a bunch of files with date modified timestamp at the end of the filename? Why is the sky not purple? I realise the question of why this sky is blue is considered reasonably often here, one way or another.  You can take that knowledge as given.  What I'm wondering is, given that the spectrum of Rayleigh scattering goes like $\omega^4$, why is the sky not purple, rather than blue?    I think this is a reasonable question because  (or, strictly, violet or indigo) in rainbows, so why not across the whole sky if that's the strongest part of the spectrum?  There are two possible lines of argument I've  and I'm not sure which (if not both) is correct.  Firstly, the Sun's thermal emission peaks in the visible range, so we do actually receive less purple than blue. Secondly, the receptor's in our eye are balanced so that we are most sensitive to (roughly) .  Our eyes are simply less sensitive to the purple light than to the blue. What does [param: NotNull] mean in C#? How To Set Default Wallpaper As Login Screen Wallpaper [Automatically]? identity element of $(D_n ,\gcd)$ Let $x*y=\gcd(x,y)$ on $D_n=\{x\in \mathbb N:x |n\}$. I have to prove that $(D_n,*)$ is a commutative monoid and I have a problem when finding the identity element.  $x*e=x$  So $gcd(x,e)=x \to e=xk,k\in \mathbb N^*$ and $e \leq n$  A good $e$ is $0$ but it's not in $D_n$ Brasero says it won't burn the CD because the file is too big, what's going on? Closing Etiquette: Why Do Some Answer *and* Close? I've noticed quite a few cases () where people not only vote to close a question, but then also answer said question. At best this is just silly, and at worst it is totally hypocritical and seems almost like rep whoring (since often the closers answers are the only ones that remain to be voted on since no new answers can be given).  If you want to close a question, it makes more sense to simply add a comment if you feel the need to say something. This also leaves the option open for the author of the question to delete it if they want to. If the author realizes they've asked a duplicate, or they want to avoid the onslaught of downvotes that can often accompany a closed question, they should be allowed to delete it. However, if any answers to the question have upvotes, the author can't delete it.  So why do people answer and close? Should we try to crack down on this sort of thing, via either new features, clearly stating it in the FAQs, or just getting the word out through commenting when we see it?  EDIT: Just to clarify, I'm asking this in relation to SO, not MetaSO. Remove .php extension with .htaccess Command run in terminal, not with shortcuts As explain in this , I want to add shortcuts to switch workspaces (in Mate).  I found a way to switch workspace for the terminal: wmctrl -s $(wmctrl -d | grep "*" | awk '{print $1+1}').  But this command line does not work when I add it in the shortcut manager. Does any one know why ? Flirtatious Primes Here's a possibly interesting prime puzzle. Call a prime $p$ flirtatious if the sum of its digits is also prime. Are there finitely many flirtatious primes, or infinitely many? Relative pronouns "where" and "when": where can they be omitted? I need to prove this equivalence   Let $a,b \in \mathbb{Q^{+}}$ then $\sqrt{a} + \sqrt{b} \in \mathbb{Q} $ if and only if $\sqrt{a} \in \mathbb{Q}$ and $\sqrt{b} \in \mathbb{Q}$  I have already proved the reciprocal (the obvious part) but I am having difficulties with the other part  Please any hint will be appreciated.  Thanks in advance. What is time dilation really? I'm not quite sure how the total attack bonus interacts with BAB.   Can you make more attacks than shown by your BAB (e.g. +11/+6/+1 BAB allows you to make 3 attacks) by having a high enough DEX, STR or other attack bonus modifiers? Assuming I have +11/+6/+1 BAB, and a spell gives me +6 attack bonus, would that make me able to attack as if I had +17/+12/+7/+2 BAB, giving me an extra attack?)   Can you make multiple attacks even if you have one of your stats drained, making your attack bonus negative, or less than 5?      It says in the SRD that the formula for attack bonus in melee is this:       Base attack bonus + Strength modifier + size modifier   I've also been told that you can make multiple attacks in one turn, but each attack gains a -5 penalty to attack bonus. If $11z^{10}+10iz^9+10iz-11 = 0$. Then possible value of $\mid z \mid,$ is If $11z^{10}+10iz^9+10iz-11 = 0$. Then possible value of $\mid z \mid,$ is  $\bf{My\; Try::}$ Given $11z^{10}+10iz^9+10iz-11 = 0\Rightarrow \displaystyle z^9 = \frac{11-10iz}{11z+10i}.$  Now Put $z = x+iy\;,$ we get $\displaystyle (x+iy)^9 = \frac{11-10i(x+iy)}{11(x+iy)+10i} = \frac{(11+10y)-10ix}{11x+i(10+11y)}$  Now i did not understand how can i solve it,  Help Required  Thanks