Is this a new operation?
what operation repeated $n$ times results in the addition operator?
How do I get an iball 3.5G modem working on Ubuntu? I purchased iball 3.5G  connect wireless modem 1 month before. I am trying to connect it with my laptop which is having ubuntu Operating System. After plug-in it to the ubuntu system it is not connecting with net.   This modem is plug and play but after plugging it nothing is displaying to the system.  I am expecting step-by-step method to connect this modem with my ubuntu 12.04 LTS sysetm from your expert's advice. is this set a regular surface? I'm reading "Differential Geometry of Curves and Surfaces of Manfredo Docarmo" I'm doing  the exercises of the chapter 2. Here is the definition of regular surface that we are following:   I have problems with this exercise:   Is with the first part, I think that it's not true that it's a regular surface (the second it is). I don't know how to prove that something is not a regular surface. Why does a force not do any work if it's perpendicular to the motion? I have a book that says the Moon's orbit is [in this context assumed to be] circular. The Earth does no work on the moon. The gravitational force is perpendicular to the motion. Why is there no work done if support force is perpendicular to the motion? I was wondering what is the purpose of piping the downloaded file by curl into sudo -E bash - in the following shell:   curl -sL https://deb.nodesource.com/setup_5.x | sudo -E bash - English version of Ubuntu with Italian keyboard I want to install Ubuntu in ENGLISH (UK) but I have an ITALIAN keyboard, which has a different layout to the English keyboard. How can I install Ubuntu in English but select an Italian layout for the keyboard. I tried, but it would only allow me to select an English keyboard. Thanks Are the various "Zelda" games supposed to take place in a common universe? I'm new to modelbuilder and python. I have used modelbuilder to iterate through all rows in a shapefile (Points), process them, and produce a seperate output shapefile for each row.  The filename is generated using an inline variable (I think that is the correct terminology).  i.e. all output files have identical filenames except that the value of the PointID from the original input file is appended to the filename to enable them to be distinguished.  This works fine.  I've also written a python script to take the above output files from the model one at a time and do additional processing.  At present the input filename is hard coded into the script (i.e. I have to edit the script to change the input filename each time I run it).  Again this works fine while just processing a single file. However, I want to integrate the model and the python script so that I can run the script for each row in the original feature class automatically.  My question is therefore, how do I replace the hard coded name of the input file with a variable in the python script and how do I pass the filename to the script. Any thoughts on a semidecadian badge for people with five years service and an average of N points per year? Given that Stack Overflow is close to its fifth birthday as a public site, has any thought been given to a 'semidecadian' badge for people who have:   been registered with the site five years (a semi-decade, hence the name), scored more than N points per year on average (where N might be 1000).   The idea behind 'average of N points per year' is to allow slow starters to gain the badge eventually, rather than ruling them out in year 1.  The details are obviously subject to tweaking.  This might be a gold badge (the platinum version would be the decadian badge, with a larger value of N required — and no-one eligible for another 5 years or so).  These would complement the current Yearling badge (which is silver). How to remove the top horizontal bar in fancyhdr? When using fancyhdr, how do you remove the top horizontal rule?  I do not want a header at all, just a footer.  This is what I do now:  \documentclass{article} \usepackage{fancyhdr} \pagestyle{fancy}  \lfoot{text} \cfoot{text 2} \rfoot{text 3}  \begin{document} Foo Bar \end{document} Find where java class is loaded from Does anyone know how to programmaticly find out where the java classloader actually loads the class from?    I often work on large projects where the classpath gets very long and manual searching is not really an option.  I recently had a  where the classloader was loading an incorrect version of a class because it was on the classpath in two different places.  So how can I get the classloader to tell me where on disk the actual class file is coming from?  Edit: What about if the classloader actually fails to load the class due to a version mismatch (or something else),  is there anyway we could find out what file its trying to read before it reads it? Show that the ring of all rational numbers, which when written in simplest form has an odd denominator, is a principal ideal domain. Show that the ring of all rational numbers $m/n$ with $n$ an odd integer is a principal ideal domain.  We haven't really discussed principal ideal domains. I've heard that this is easy, but I just lack the basic knowledge of what a principal ideal domain is. How do suggested edits work? How can I prove these statements? We have a org wide email addressed which has been "Verified" into our sandbox. I understant org wide email addressed is unsupported metadata, so this was achieved as pre deployment step.   Into our repo, we have a workflow that send email alert to that org wide email address. "  Workflow   ... &lt;senderAddress&gt;noreply@mycompany.com.au&lt;/senderAddress&gt; &lt;senderType&gt;OrgWideEmailAddress&lt;/senderType&gt;    The problem we are facing is that we are still getting the following error even if this org wide email address is verified:      You must specify a verified Org Wide Email Address for this sender   type.   Is that a bug in the metadata api or expected behaviour ? Ideally we would like to not have to do that as a post deployment step.   PS: We are running DX under api version 43.0 Why do physicists believe that particles are pointlike? String theory gives physicists reason to believe that particles are 1-dimensional strings because the theory has a purpose - unifying gravity with the gauge theories.   So why is it that it's popular belief that particles are 0-dimensional points? Was there ever a proposed theory of them being like this? And why?   What reason do physicists have to believe that particles are 0-dimensional points as opposed to 1-dimensional strings? Recovering from forgotten lock pattern My son has an impression tablet 10 and has forgot the lock pattern. How can we reset it without knowing the code? Describe in English a Turing machine that semidecides the following language - Is this solution correct? The language being L, which is described as follows:  $L$ = { $&lt;M&gt;$ | $M$ accepts the binary encodings of at least 4 odd numbers } .  My solution:  M generates the binary encodings in $\Sigma_M*$ in ascending order and uses dovetailing to interleave the computation of M on those binary encodings. As soon as four computations accept, M halts and accepts.  Is this correct? What corrections would have to be made if not? I am not sure if I am providing enough details in my solution which may cause it to be incorrect. Why does LuaTeX plus breqn quadruple output of \text{} when in display-math mode? MWE needs to be compiled with LuaTeX to reproduce the problem:  \documentclass[11pt]{report}% \usepackage{amsmath,mathtools} \usepackage{breqn}                          \begin{document} $J^{\ast} = \text{JFK} \to \text{NO} \to \text{SFO}$ \[ J^{\ast} = \text{JFK} \to \text{NO} \to \text{SFO} \] \end{document}   Gives (no compile error or any warning) the following strange output    I have to use breqn package. If I remove it, then I get the expected output    Is there a way to work around this, so I can use breqn and get correct output?  TL 2015. filelist: (compiled with lualatex)  This is LuaTeX, Version beta-0.80.0.1 (TeX Live 2015) (rev 5863)   *File List*   report.cls    2014/09/29 v1.4h Standard LaTeX document class   size11.clo    2014/09/29 v1.4h Standard LaTeX file (size option)  amsmath.sty    2013/01/14 v2.14 AMS math features  amstext.sty    2000/06/29 v2.01   amsgen.sty    1999/11/30 v2.0   amsbsy.sty    1999/11/29 v1.2d   amsopn.sty    1999/12/14 v2.01 operator names mathtools.sty    2015/11/12 v1.18 mathematical typesetting tools   keyval.sty    2014/10/28 v1.15 key=value parser (DPC)     calc.sty    2014/10/28 v4.3 Infix arithmetic (KKT,FJ)  mhsetup.sty    2010/01/21 v1.2a programming setup (MH)    breqn.sty    2015/08/11 v0.98d Breaking equations    expl3.sty    2015/12/20 v6326 L3 programming layer (loader)  expl3-code.tex    2015/12/20 v6326 L3 programming layer  l3pdfmode.def    2015/11/11 v6250 L3 Experimental driver: PDF mode flexisym.sty    2015/08/11 v0.98d Make math characters macros   cmbase.sym    2007/12/19 v0.92 mathstyle.sty    2015/08/11 v0.98d Tracking mathstyle implicitly graphicx.sty    2014/10/28 v1.0g Enhanced LaTeX Graphics (DPC,SPQR) graphics.sty    2014/10/28 v1.0p Standard LaTeX Graphics (DPC,SPQR)     trig.sty    1999/03/16 v1.09 sin cos tan (DPC) graphics.cfg    2010/04/23 v1.9 graphics configuration of TeX Live   pdftex.def    2011/05/27 v0.06d Graphics/color for pdfTeX infwarerr.sty    2010/04/08 v1.3 Providing info/warning/error messages (HO)  ltxcmds.sty    2011/11/09 v1.22 LaTeX kernel commands for general use (HO) supp-pdf.mkii pdftexcmds.sty    2011/11/29 v0.20 Utility functions of pdfTeX for LuaTeX (HO) ifluatex.sty    2010/03/01 v1.3 Provides the ifluatex switch (HO)    ifpdf.sty    2011/01/30 v2.3 Provides the ifpdf switch (HO) luatex-loader.sty    2010/03/09 v0.4 Lua module loader (HO) epstopdf-base.sty    2010/02/09 v2.5 Base part for package epstopdf   grfext.sty    2010/08/19 v1.1 Manage graphics extensions (HO) kvdefinekeys.sty    2011/04/07 v1.3 Define keys (HO) kvoptions.sty    2011/06/30 v3.11 Key value format for package options (HO) kvsetkeys.sty    2012/04/25 v1.16 Key value parser (HO) etexcmds.sty    2011/02/16 v1.5 Avoid name clashes with e-TeX commands (HO) epstopdf-sys.cfg    2010/07/13 v1.3 Configuration of (r)epstopdf for TeX Live  ***********   Update  I found another case of duplication when using breqn, which does not involve \text at all. But the solution provided below also fixes this issue. I am adding this second case here for reference just in case it might be useful. Here is MWE  \documentclass[11pt]{article} \usepackage[T1]{fontenc} \usepackage{amsmath,mathtools} \usepackage{breqn} \begin{document} \[ \underset{\mathbf{S}} {\operatorname{arg\,min}}      \sum_{i=1}^{k} \sum_{\mathbf x \in S_i}       \left\| \mathbf x - \boldsymbol\mu_i \right\|^2  \] \end{document}   The output is    After adding the patch in the answer below the correct output is now given, which is listings package in XeLaTeX: every tab in lstlisting compiles to "^^I" in the pdf In beamer class, when i compile using LaTeX, the output pdf results perfectly the way i expect it to. But when i change it to XeLaTeX, in the lstlisting environment, every tab in the code results in a "^^I"-Placeholder (See output-pdf below). How do I fix this?   if( Bedingung ) {  ^^I//Code, der nur ausgefuehrt wird, wenn die Bedingung wahr ist   }  ^^I^^I   LaTeX-Code (Reduced to the minimum, one frame as an example):  \begin{document}     \begin{frame}[fragile]{if-Statements}         \begin{block}{Syntax}                \begin{lstlisting} if( Bedingung ) {     //Code, der nur ausgefuehrt wird, wenn die Bedingung wahr ist }                    \end{lstlisting}         \end{block}         \begin{block}{Logik}                 \begin{itemize}                  \item Alles innerhalb eines if-Blocks wird nur ausgeführt, wenn die Bedingung (in Klammern) wahr ist.             \end{itemize}         \end{block}     \end{frame} \end{document} Draw power from a portable mobile charger to power circuits I usually power my beginner prototype circuits using mb102 power supply board, but it needs an external elimeter to draw power and then regulate it.  I was looking for a portable solution for my 5 volt and 3.3 volt circuit needs and came up with using a portable battery charger for mobile phones.  I tried powering up a simple transistor and LED circuit with it but it wouldn't power-up.   I feel that there is some load sensing circuit in the portable charger which doesn't detect these low power circuits.  I also tried connecting different resistors to the charger, the charger outputs 5 Volts for a few seconds and then again shuts down and doesn't stay ON continuously.  It would be really comfortable to use a portable charger since it could be charged using a phone charger and would be very handy.  What can I do to make the charger output power on low loads?