What happens to Spider-Man's webs?
How much web can Spider-Man produce?
How to make tr aware of non-ascii(unicode) characters? I'm trying to remove some characters from file(UTF-8). I'm using tr for this purpose:   tr -cs '[[:alpha:][:space:]]' ' ' &lt;testdata.dat    File contains some foreign characters (like "Латвийская" or "àé"). tr doesn't seem to understand them: it treats them as non-alpha and removes too.  I've tried changing some of my locale settings:  LC_CTYPE=C LC_COLLATE=C tr -cs '[[:alpha:][:space:]]' ' ' &lt;testdata.dat LC_CTYPE=ru_RU.UTF-8 LC_COLLATE=C tr -cs '[[:alpha:][:space:]]' ' ' &lt;testdata.dat LC_CTYPE=ru_RU.UTF-8 LC_COLLATE=ru_RU.UTF-8 tr -cs '[[:alpha:][:space:]]' ' ' &lt;testdata.dat   Unfortunately, none of these worked.  How can I make tr understand Unicode? I've been thinking of animating some dice and while most are easy to make, I'm having some trouble figuring out a way to generate a regular dodecahedron. I could hand build it but it would be potentially uneven. Would using the base of a 5 sided cylinder and then some variation on spin be the best option or is there a better way? How do I solve this limit: $\lim _{x \to 0} \left(\frac{ \sin x}{x}\right)^{1/x}$? If a function $f$ is continuous $\implies$ $|f|$ is continuous.(Answered by Myself) $(i)$ Given a function $f:E \rightarrow \mathbb{R}$ define $|f|:E \rightarrow \mathbb{R}$ by $|f|(x)=|f(x)|$ for $x \in E$ show if $f$ is continuous at $c \in E$ then so is $|f|$.        $(ii)$ Now the converse is not true, find $f$ such that $|f|$ is continuous but $f$ is not. Bounded measurable function and integral with charcteristic function Showing this metric space is complete Let $X=(0,1]$ and $d(x,y)=\left|\frac{1}{x}-\frac{1}{y}\right|$. I've proven $(X,d)$ is a metric space but I don't know how to show its completeness. How can I do that? Is it possible to sort non-stackable items in minecraft? are super sweet.  But, I have a skeleton farm, and am getting tons of non-stackable drops.  Since armor can be smelted into iron/gold, I'd like to smelt those drops in a furnace, and burn bows in a furnace.  And trash all leather armor.  Is there a way to sort out these non-stackable items in vanilla survival? How do I evaluate $\sum_{k=0}^{n} {n \choose k}{m \choose k}$ for a given $n$ and $m$.  I have tried to use binomial expansion and combine factorials, but I have gotten nowhere. I don't really know how to start this problem.  The answer is ${n+m \choose n}$. Any help is greatly appreciated.  EDIT: I'm looking for  a proof of this identity. Wires do not connect in Circuitikz I've been trying to use relative coordinates to make my drawings more precise but it seems I don't know how the command \node works since I've been having this problem while connecting a circuit element to another:    I'm trying to eliminate the blank between the two wires.  This is the minimal code:  \documentclass{book} \usepackage[siunitx,RPvoltages]{circuitikz} %Circuit Schematics/Diagram \usetikzlibrary{arrows,shapes,calc,positioning} \begin{document}     \begin{circuitikz}             \path (0,0) coordinate (C);             % Comparatore             \path (C) + (0,-1) + (1,0) coordinate (com) node[above]{};             \path (com) + (1.5,-1) node[op amp] (comp) {};             % Collegamenti Comparatore             \node (G1) at ([shift=({-1.3cm,0cm})]comp.-) {};             \draw (G1) -- (comp.-);             \node (G2) at ([shift=({-1.3cm,0cm})]comp.+) {};             \draw (G2) -- (comp.+);             \draw (C) -- (G1); % Collegamento Rettificatore - Comparatore         \end{circuitikz} \end{document}   Thanks for any help! Number of Homomorphisms from $\Bbb{Z}_m$ to $\Bbb{Z}_n$ I have been using Ubuntu 12.04 for quite a while and have never had a problem come at me out of the blue like this. I'm trying to install python 3.2 on my Ubuntu system and every time I run the code to compile the python source, I get this error:  'Command 'sudo' is available in '/usr/bin/sudo' The command could not be located because '/usr/bin' is not included in the PATH environment variable. sudo: command not found'   I've also tried running gksudo command to view what my environment shows but I pretty much get the same error. I hope this is not a repeat question. I tried searching but couldn't come up with the right search words for this question.  I see the following in the sidebar of my flagging history tab:    I notice that I have raised 28 helpful flags from my user page, but I see "27 deemed helpful" and "1 deemed helpful". What is the difference between the top half and the bottom half of the entries in the flagging history sidebar? How should I interpret the results displayed in the sidebar? HTML 5 Video stretch When (and why) should you take the log of a distribution (of numbers)? Hamiltonian Monte Carlo for dummies Could you provide a step-by-step for dummies explanation of how Hamiltonian Monte Carlo work?  PS: I've already read the answers here, , and here, , and here,  and they do not address it in a step-by-step way. I need to render a model on a transparent background. The models have a light source so they should be casting a shadow on a surface (the XY plane). The purpose for this is to overlay the rendered images (out of blender) on an image of the actual surface, so I want to generate the render including a semi-transparent shadow.  I don´t have any problem rendering the models on transparent background, but I can not make a shadow appear. I tried adding a surface below the model so the shadow can fall on it, but now there's the problem of keeping the surface from rendering.  How can I render the shadow on a transparent background? Highest quality website screenshot? I have created a  that i would like to add to my portfolio, but i'm having a hard time getting high quality screenshots of the full site. I tried to save the website as PDF, but that was full of errors, other online services cant recreate the images and so on. I've also just tried to take regular screenshots on the mac at put it all together, but it really lost a lot of quality when i scaled it down.  Any good ideas? :) When should we use "can", "could", "will", "would"? Most people say I wish I could, I wish you would.    Can we use I wish I can, I wish you will?    I'd like to know what the main differences between the usage of can/will and could/would are when wishing.  Is it related to the subjunctive? Because one says “I wish I were”, not “I wish I am”, so are would and could the subjunctive forms of can and will?  Or is it something else entirely? I am testing against the following test document:  &lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"                        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"&gt; &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;    &lt;head&gt;         &lt;title&gt;hi there&lt;/title&gt;     &lt;/head&gt;     &lt;body&gt;         &lt;img class="foo" src="bar.png"/&gt;     &lt;/body&gt; &lt;/html&gt;   If I parse the document using lxml.html, I can get the IMG with an xpath just fine:  &gt;&gt;&gt; root = lxml.html.fromstring(doc) &gt;&gt;&gt; root.xpath("//img") [&lt;Element img at 1879e30&gt;]   However, if I parse the document as XML and try to get the IMG tag, I get an empty result:  &gt;&gt;&gt; tree = etree.parse(StringIO(doc)) &gt;&gt;&gt; tree.getroot().xpath("//img") []   I can navigate to the element directly:  &gt;&gt;&gt; tree.getroot().getchildren()[1].getchildren()[0] &lt;Element {http://www.w3.org/1999/xhtml}img at f56810&gt;   But of course that doesn't help me process arbitrary documents.  I would also expect to be able to query etree to get an xpath expression that will directly identify this element, which, technically I can do:  &gt;&gt;&gt; tree.getpath(tree.getroot().getchildren()[1].getchildren()[0]) '/*/*[2]/*' &gt;&gt;&gt; tree.getroot().xpath('/*/*[2]/*') [&lt;Element {http://www.w3.org/1999/xhtml}img at fa1750&gt;]   But that xpath is, again, obviously not useful for parsing arbitrary documents.  Obviously I am missing some key issue here, but I don't know what it is.  My best guess is that it has something to do with namespaces but the only namespace defined is the default and I don't know what else I might need to consider in regards to namespaces.  So, what am I missing? "All X" vs. "all of X" vs. "all the X" Is there any difference between "all X", "all of the X", "all the X"? E.g.,        all friends   all of the friends   all the friends