v2.81.16 cycles; render shows nothing, finishes in .01 ms
Blank image when I render
Associativity of symmetric difference of sets Can I rephrase the sentence "Can you explain this word to me?" into "Can you explain me this word." How to see download count of an Android app on Google Play store? I cannot see the download counts of one app on Google Play.   How can we know that number of one app? Showing that $\int_0^\infty x^{-x} \mathrm{d}x \leq 2$. This integral is very closely related to the sophmores dream that states  $$ \int_0^1 x^{-x}\mathrm{d}x = \sum_{n=1}^\infty n^{-n} = 1.27\ldots $$  For example here   Now I want to bound the integral, and showing that is less that 2.  For the interval $[0,1]$ a good bound is rewriting it to $\exp(x\log x)$ and using the expansion   $$ 1 - x \log(x) + \frac12 (-x \log(x))^2$$  but how does one handle $[1,\infty)$ ? In this answer here     gives bounds to the integral, but they are not tight enough.. So to taste my question again, how does one prove that   $$ \int_0^\infty \frac{\mathrm{d}x}{x^x} \leq 2 $$ Get Record Type Developer Name without SOQL Query Biblatex: URL-breaking not working in DVI-mode I'm preparing my bibliography and noticed that biblatex-printbibliography produces Overfull \hbox several times.  Examples (gray lines indicates text margins, red line is the physical page margin):        Why is hyperref line-breaking not working as expected using pdflatex or even latex -&gt; dvipdfm BUT not using latex -&gt; dvips -&gt; ps2pdf?  Also it would be great if someone could point out how I can raise the indentation of the second (and following) lines, as this might look better.  edit: Customized question, as the answer given by lockstep solved the third problem. The second problem seems to be identical to the first.  \documentclass[12pt]{scrbook} \usepackage[english]{babel} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[ps2pdf]{hyperref} %\usepackage[ps2pdf,breaklinks=true]{hyperref} %This doesn't change anything. %\usepackage{breakurl} %That makes no difference either.  \usepackage[a4paper,twoside,showframe]{geometry} %show text margins  \usepackage[style=alphabetic,backend=biber,maxnames=4,minnames=3,maxbibnames=99]{biblatex} \bibliography{biblatex-issue}  \begin{document} \nocite{*}  \printbibliography[heading=subbibliography,type=article,prefixnumbers={A-}] \printbibliography[heading=subbibliography,type=book,prefixnumbers={B-}] \printbibliography[heading=subbibliography,type=online]  \end{document}   And the bib-file:  @online{GLS:datasheet,     title         = "GLS Datasheet",     organization  = "Optoelectronics Research Centre",     howpublished ="Website",     date = "2004-09",     urldate="2013-07-01",     url ="http://www.southampton.XXXX",     address       = "Southampton, United Kingdom" } @book {Lifante:Fundamentals,     title = "Integrated Photonics: Fundamentals",     author = "Lifante, Ginés",     publisher = "J.Wiley",     address = "Chichester",     year = "2003",     type = "text",     isbn = "9780470848685" } @article{Labadie:First_fringes,     author = {Labadie, L. and Mart\'{\i}n, G. and Anheier, N. C. and Arezki, B. and Qiao, H. A. and Bernacki, B. and Kern, P.},     title = {First fringes with an integrated-optics beam combiner at 10},     DOI= "10.1051/0004-6361/201116727",     journal = {A\&amp;A},     year = 2011,     volume = 531,     pages = "A48" }     P.S.: I noticed that the visiting-date of the GLS-datasheet is wrong ;-) Screen resolution stuck at 1024x768 Iterating each character in a string using Python In C++, I can iterate over an std::string like this:  std::string str = "Hello World!";  for (int i = 0; i &lt; str.length(); ++i) {     std::cout &lt;&lt; str[i] &lt;&lt; std::endl; }   How do I iterate over a string in Python? Suggested reading for renormalization (not only in QFT) What papers/books/reviews can you suggest to learn what  "really" is?  Standard QFT textbooks are usually computation-heavy and provide little physical insight in this regard - after my QFT course, I was left with the impression that Renormalization is just a technical, somewhat arbitrary trick (justified by experience) to get rid of divergences. However, the appearance of Renormalization in other fields of physics  approach in statistical physics etc.), where its necessity and effectiveness have, more or less, clear physical meaning, suggests a general concept beyond the mere "shut up and calculate" ad-hoc gadget it is served as in usual QFT courses.   I'm especially interested in texts providing some unifying insight about renormalization in QFT, statistical physics or pure mathematics. If I multiply two numbers, say $3$ and $5$, I know it means add $3$ to itself $5$ times or add $5$ to itself $3$ times.    But If I multiply two matrices, what does it mean ?  I mean I can't think it in terms of repetitive addition.       What is the intuitive way of thinking about multiplication of matrices? After enabling hibernate grub menu appears on start-up with 30s timeout My system is not dual boot just single OS UBUNTU 16.04. Prior to making the following changes, the Grub screen would not appear at start-up (OK).  After following these steps from  to enable hibernate in the system menu:   Open terminal and enter;   sudo nano /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla  add the lines into the empty file;  [Re-enable hibernate by default in upower] Identity=unix-user:* Action=org.freedesktop.upower.hibernate ResultActive=yes  [Re-enable hibernate by default in logind] Identity=unix-user:* Action=org.freedesktop.login1.hibernate;org.freedesktop.login1.handle-hibernate-key;org.freedesktop.login1;org.freedesktop.login1.hibernate-multiple-sessions;org.freedesktop.login1.hibernate-ignore-inhibit ResultActive=yes  ^X then Y to save (a filename was suggested and I accepted without taking note).  Reboot for the changes to take effect.   hibernate now works and appears in the menu (OK) but whenever I reboot I now get a Grub menu at start up with a full 30 second timeout (NOK). I tried playing around with the Grub menu timeout settings but still get the full 30 sec timeout.  How do I stop the Grub menu from appearing and reduce my boot time to what it was before I made these changes.   Current Grub settings;   GRUB_DEFAULT="0" GRUB_HIDDEN_TIMEOUT="0" GRUB_HIDDEN_TIMEOUT_QUIET="true" GRUB_TIMEOUT="1" GRUB_DISTRIBUTOR="`lsb_release -i -s 2&gt; /dev/null || echo Debian`" GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX="" How does Java's PreparedStatement work? How to convert an instance of std::string to lower case I want to convert a std::string to lowercase. I am aware of the function tolower(). However, in the past I have had issues with this function and it is hardly ideal anyway as using it with a std::string would require iterating over each character. Is there an alternative which works 100% of the time? Is there a rational number between any two irrationals? Suppose $i_1$ and $i_2$ are distinct irrational numbers with $i_1 &lt; i_2$.  Is it necessarily the case that there is a rational number $r$ in the interval $[i_1, i_2]$?  How would you construct such a rational number?  [I posted this only so that the useful answers at  could be merged here before that question was deleted.] I seem to be having issues when I try and save the output file as a .png, or .jpeg for that matter. I've set up my user preferences, File, Render Output to my desktop as well as render output in the editor window. What am I missing here? I'm obviously very new to this program and your help would be appreciated. Thanks for your time What is the word or term used to describe doing an activity or work with a high level of concentration and intention, trying your best? I find in many places mentions of pre-amplifiers being used to boost audio signals prior to feeding to a power amplifier.  Wikipedia's article on  gives some hints at their usage, but it doesn't really explain why it would be necessary to have two amplifiers in series rather than a single one with greater gain.  If a pre-amp is just a power amp with a smaller gain, what's the point, and why the distinction between the two kinds? Is the distinction in function, or simply purpose? It seems like I'm doing something wrong when using foreach variables to indicate node numbers. The two foreach loops are anchoring the paths to the east of each node. Why does this happen?    \documentclass{article}  \usepackage{tikz} \usetikzlibrary{backgrounds,fit,patterns,decorations.pathreplacing,calc}  \makeatletter \tikzset{   labelnode/.style={draw=none, fill=none, black},   latentnode/.style={draw, minimum width=5mm, shape=circle, ultra thick, black},   dagconn/.style={arrows=-&gt;, black, thick}, } \makeatother  \begin{document} \begin{tikzpicture}[scale=1]  \pgfmathsetmacro{\colgap}{1.6}  \pgfmathsetmacro{\rowgap}{1.3}   \node[labelnode] (x1) at (\colgap*0,\rowgap*1) {$X_1$};  \node[labelnode] (x2) at (\colgap*1,\rowgap*1) {$X_2$};  \node[labelnode] (x3) at (\colgap*2,\rowgap*1) {$X_3$};   \node[latentnode,blue] (x4) at (\colgap*0,\rowgap*0) {$X_4$};  \node[latentnode,red] (x5) at (\colgap*1,\rowgap*0) {$X_5$};  \node[labelnode] (x6) at (\colgap*2,\rowgap*0) {$X_6$};   \foreach \c in {1,...,2} {    \foreach \r in {1,...,2} {      \pgfmathsetmacro{\st}{(((\r-1)*3)+\c)}      \pgfmathsetmacro{\en}{\st+1}      \draw[dagconn] ([xshift=0.2cm]x\st) to ([xshift=-0.9cm]x\en);    }  }   \foreach \c in {1,...,3} {    \foreach \r in {1,...,1} {      \pgfmathsetmacro{\st}{((\r-1)*3)+\c}      \pgfmathsetmacro{\en}{\st+3}      \draw[dagconn] (x\st) to (x\en);    }  } \end{tikzpicture} \end{document} When doing calculations on very large numbers where integral data types such as double or int64 falls short, a separate class to handle such large numbers may be needed.    Does anyone care to offer an efficient algorithm on how best to do this? About finding the function such that $f(xy)=f(x)f(y)-f(x+y)+1$