Why does itemsep not work in setbeamertemplate?

I'm trying to change the spacing between itemize items in a beamer frame.  I've read that you should adjust beamer settings using the setbeamertemplate command so I'd like to follow that advice.  I can make some changes, like making the font \small and adjusting the vertical spacing before the itemize.  But wherever I try and put vspace or itemsep it seems to make no difference to the spacing between items.  Why is this, and how can I achieve, say, 5cm spacing between items using setbeamertemplate?    \documentclass{beamer} % itemsep does nothing here: \setbeamertemplate{itemize/enumerate body begin}{\vspace{1cm}\tiny\itemsep5cm} % vspace and itemsep do nothing here: \setbeamertemplate{itemize item}{\vspace{5cm}\itemsep5cm---} \begin{document} \begin{frame}{Title}{subtitle} Foo \begin{itemize} \item First \item Second \item Third \end{itemize} \end{frame} \end{document}


Beamer: Vertical alignment of multi-column ToC

In my LaTeX  presentation I have a long Table of Contents, which has been split across two columns by using the  package. The problem is that I have not found any way to control vertical alignment in the multicols environment. Right now the left column starts lower than the right column, which looks weird. Instead, I would like the left column, or both columns, to be vertically aligned to the top.  I've found some related questions but nothing that solves my problem.  Look at the MWE shown below. As you can see right before Section 3, I tried adding a \vfill along a manual column break, but it didn't help... (The manual column break was added in order to keep Section 3's subsections together with the section in ToC).  Do you have any tricks?  Screenshot of the ToC slide:    MWE:  % MWE showing problems with vertical spacing in multicol ToC \pagenumbering{arabic} \documentclass[compress,14pt,t]{beamer} \usepackage[latin1]{inputenc} \usepackage{multicol} \usepackage{charter} \frenchspacing  \begin{document}  \begin{frame}     \frametitle{Outline}     \begin{multicols}{2}         \tableofcontents     \end{multicols} \end{frame}  \section{Section 1} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}     \subsection{Subsection 4}     \begin{frame}Test\end{frame}  \section{Section 2} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}  \addtocontents{toc}{\newpage}           % Splits manually the ToC into 2 columns %\addtocontents{toc}{\vfill\newpage}    % No difference \section{Section 3} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}  \section{Section 4} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}     \subsection{Subsection 3}     \begin{frame}Test\end{frame}     \subsection{Subsection 4}     \begin{frame}Test\end{frame}  \section{Section 5} \begin{frame}Test\end{frame}     \subsection{Subsection 1}     \begin{frame}Test\end{frame}     \subsection{Subsection 2}     \begin{frame}Test\end{frame}  \end{document}


Choosing numbers without consecutive numbers.

In how many ways can we choose $r$ numbers from $\{1,2,3,...,n\}$,   In a way where we have no consecutive numbers in the set? (like $1,2$)


Hello, could you help me to understand the next error? texmaker (Mac)

This is the error!:  Overfull \hbox (12.10773pt too wide) in paragraph at lines 13--19  I don´t understand it!  It has apareces when i try to compilate with the next document:  \documentclass[11pt]{book} \usepackage[utf8]{inputenc} \usepackage[spanish,mexico]{babel} \usepackage[T1]{fontenc} %\usepackage{amsmath} %\usepackage{amsfonts} %\usepackage{amssymb} %\usepackage{graphicx} \usepackage{apacite}  \title{Manual de estrategias psicopedagógicas en el manejo de grupo desde la perspectiva sociocultural} \author{Itzel Viridiana Gutiérrez Ruiz\\Mayra Yurieth Hernández Robledo} \date{} \begin{document} \frontmatter \maketitle %\tableofcontents %\mainmatter \include{introduccion} \backmatter \bibliographystyle{apacite} \bibliography{bibliografia} \end{document}


Calling Overridden Constructor and Base Constructor in C#

I have two classes, Foo and Bar, that have constructors like this:  class Foo {     Foo()     {       // do some stuff     }      Foo(int arg)     {       // do some other stuff     } }  class Bar : Foo {     Bar() : base()     {       // some third thing     } }   Now I want to introduce a constructor for Bar that takes an int, but I want the stuff that happens in Bar() to run as well as the stuff from Foo(int).  Something like this:  Bar(int arg) : Bar(), base(arg) {   // some fourth thing }   Is there any way to do this in C#?  The best I have so far is putting the work done by Bar() into a function, that also gets called by Bar(int), but this is pretty inelegant.


Do declined comment flags count towards the ban?

It seems like only post flags' declination counts towards the ban.  Do declined comment flags also count towards the ban?


Should proper nouns used as verbs be capitalized?

When a proper noun like "Skype" is used as a verb ("Skyping"), should it be capitalized?  My thinking is that it should be capitalized because the root is a proper noun.  Does anyone know of a rule about this question?


Basically I have 1889 rooms discovered and I am at 200.5% and I absolutely cannot see which room I need to discover in order to make that final 0.1%  Is there a completed a map that would show me where I might be missing a room?


I was trying to upgrade the PHP packages on my Ubuntu 14.04 LTS server and I keep getting errors. I know there is a duplicate of this Qn but i removed the error causing file from /var/cache/apt/archives/ but it did not work.  I ran these commands:  sudo apt-add-repository ppa:ondrej/php5 sudo apt-get autoremove sudo apt-get update sudo apt-get -f install   Then I got this:  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following packages will be REMOVED:   apache2-mpm-prefork apache2.2-bin apache2.2-common php5-dev php5-gd The following NEW packages will be installed:   apache2-bin apache2-data libjson-c2 php5-json php5-ssh2 The following packages have been kept back:   libgd2-xpm-dev libssl-dev openssl The following packages will be upgraded:   apache2 libssh2-php php-pear php5 php5-cli php5-common php5-curl php5-fpm php5-mcrypt php5-mysql 10 upgraded, 5 newly installed, 5 to remove and 3 not upgraded. 1 not fully installed or removed. Need to get 375 kB/8007 kB of archives. After this operation, 2457 kB disk space will be freed. Do you want to continue [Y/n]? y Get:1 http://ppa.launchpad.net/ondrej/php5/ubuntu/ precise/main php-pear all 5.5.30+dfsg-1+deb.sury.org~precise+1 [373 kB] Get:2 http://ppa.launchpad.net/ondrej/php5/ubuntu/ precise/main php5 all 5.5.30+dfsg-1+deb.sury.org~precise+1 [1220 B] Fetched 375 kB in 0s (1074 kB/s) perl: warning: Setting locale failed. perl: warning: Please check that your locale settings:     LANGUAGE = "en_US:en",     LC_ALL = (unset),     LC_CTYPE = "UTF-8",     LANG = "en_US.UTF-8"     are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory (Reading database ... 96522 files and directories currently installed.) Unpacking apache2-bin (from .../apache2-bin_2.4.16-4+deb.sury.org~precise+4_amd64.deb) ... dpkg: error processing /var/cache/apt/archives/apache2-bin_2.4.16-4+deb.sury.org~precise+4_amd64.deb (--unpack):  trying to overwrite '/usr/share/man/man8/apache2.8.gz', which is also in package apache2.2-common 2.2.22-1ubuntu1.10 dpkg-deb (subprocess): subprocess data was killed by signal (Broken pipe) dpkg-deb: error: subprocess <decompress> returned error exit status 2 Processing triggers for man-db ... Errors were encountered while processing:  /var/cache/apt/archives/apache2-bin_2.4.16-4+deb.sury.org~precise+4_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)


I'm trying to work out the partial derivatives of a function $L$ in terms of $x_i$: $$ A \in \mathbb{R}^{m x n} \quad b \in \mathbb{R}^m \quad x \in \mathbb{R}^n $$ $$\begin{aligned} L(x) &= \left\|{Ax - b }\right\|^2 \\&= (Ax-b)^T(Ax-b) \\ &= x^TA^TAx - b^TAx - x^TA^Tb + b^Tb\end{aligned}$$ All four of these terms are scalars so I think I can transpose the third term to get: $$\begin{aligned} &= x^TA^TAx - 2b^TAx + b^Tb\end{aligned}$$ I'm a little stuck on how to transform $x^TA^TAx$ further. Calculating the partial derivatives, the final term $b^Tb$ is constant so goes to zero, the second term has coefficient vector $2b^TA$ so we just drop the $x$, its again the first term I'm stuck on: $$\frac{\partial{L(x)}}{\partial x} = ??? -2b^TA$$ What's the derivative of $x^TA^TAx$ in terms of $x$?  How you work it out? Update: After looking at the potential duplicate, I think I'm mostly covered - however it's not immediately obvious to me why: $$\frac {\partial(x^TMx)} {\partial x}=(M+M^T)x$$ How is this rule derived?


What is the status of Mpemba effect investigations?

There is this puzzling thing that is called : paradoxically, warm (35°C) water freezes faster than cold (5°C) water.  As a physisist, I've been asked about it several times already. And I have no definite answer to that, apart from the standard: "there are many things that can influence it".  So, does anyone knows about the status or progress on that effect? Any recent reviews, publications or other references?


I have a problem with my HTML5 webpage that I haven't been able to research an answer for. Im using swedish letters in the text (åäö) and started out by using UTF-8 encodig as such:  <!DOCTYPE html> <html lang = 'sv'>  <head>     <title> </title>     <meta charset='utf-8'>     <meta name="description" content=' '>     <link rel = 'stylesheet' href = './css/auroracss.css'> </head>   This doesn't work for displaying the swedish letters in 3 out of 4 of my HTML5 pages, as I get the � chars when I preview. However, for the fourth page, using exactly the same head tag, the characters are displayed properly.   When I  switch out UTF-8 to ISO-8859-1 the opposite is true - displaying the characters will work fine for 3 out of 4 pages but the same one which displayed properly with UTF-8 will show  � chars when the ISO enconding is applied.  Everything validates.   I would like to stick to only one encoding choice here and not mix them even though that may be a quick fix. What is the cause for the problem?


Convert datetime.timedelta Object to HH:MM

My database table has a column whose datatype is datetime, so when queried it returns HH:MM:SS. However, using Python it returns (datetime.timedelta(0, 57360),).  This is obviously the time difference in seconds. How do I convert the returned object into a string in the format HH:MM?


What are matter waves made of and what is their speed?

We know electromagnetic waves are made of oscillating  electric and magnetic fields that can travel at the speed of light without a need for a medium. But, how about matter waves proposed by de Broglie? What are they made of? What is their speed? Do they need a medium to travel?


Plotting Normal distribution in pgfplots

I'm trying to reproduce the following diagram in TikZ and pgfplots.   My MWE with regenerated graph is below:  \documentclass{standalone} \usepackage{pgfplots}  \begin{document}  \pgfmathdeclarefunction{gauss}{2}{%   \pgfmathparse{1/(#2*sqrt(2*pi))*exp(-((x-#1)^2)/(2*#2^2))}% }  \begin{tikzpicture} \begin{axis}[   no markers,    domain=0:6,    samples=100,   axis lines*=left,    xlabel=$x$,   every axis y label/.style={at=(current axis.above origin),anchor=south},   every axis x label/.style={at=(current axis.right of origin),anchor=west},   height=5cm,    width=12cm,   xtick=\empty,    ytick=\empty,   enlargelimits=false,    clip=false,    axis on top,   grid = major   ]   \addplot [very thick,cyan!50!black] {gauss(3, 1)}; \draw [yshift=1.4cm, latex-latex](axis cs:2, 0) -- node [fill=white] {$0.683$} (axis cs:4, 0); \draw [yshift=0.3cm, latex-latex](axis cs:1, 0) -- node [fill=white] {$0.954$} (axis cs:5, 0);   \end{axis}  \node[below] at (1, 0)  {$\mu - 2\sigma$};  \node[below] at (2, 0)  {$\mu - \sigma$};  \node[below] at (3, 0)  {$\mu$};    \end{tikzpicture}  \end{document}     Issues   Nodes are not properly placed. How to remove y-axis? How to draw vertical dotted line?   Any help will be highly appreciated. Thanks


How to simplify streets such that seperate driving tracks are reduced?

Streets in Openstreetmap have more detail than I need. For instance I do not need seperate street tracks for each driving direction, instead I just want to show the general path of the street. Example:    OSM linestrings for a street    Simpified linestring(s) (here it is just one, but in case of sidearms would be > 1)  input:  collection of linestrings output: collection of linestrings  simplified lines = f(osm lines) f = ?   the output is a collection as well, since sidearms should remain available.  How do I programatically simplify such linestring collections?  Would like to use JTS, NTS, GEOS but not PostGIS if possible.


What exactly does duty free mean at the various airports? Does it mean that the items are cheaper because they have no tax/duty applied on it OR does it mean the item would "not count" for the free allowance amount at our home country?  Just to add, I checked the prices of various items at Doha airport duty free shops (for iPhones, perfumes, etc) but did not find much price difference from what is available in India? So wanted to understand.


Driver for Realtek rtl8821ce (Lenovo 720S-13ARR ultrabook)

I built the required module for the 8821ce chip from source (). 2.4GHz wifi is working fine, however 5GHz as well as bluetooth is not available. Do I miss something or is it just not implemented completely by now?


How to redirect to the list where the document is located

I am defining an email message which I want to contain in its body a link to the list where the document is located. I am doing this to approve some documents within a Workflow that will be reaching certain recipients. I would like that when you click on the link it will be redirected directly to the list where the document is located.


Does the appositive in this sentence need to be set off with commas?

On the freelancing website Upwork, there is a US Punctuation and Mechanics test one can take to boost credibility on one's profile for potential clients. These tests are administered by third-party companies that often hire non-native English speakers, so they're known to have some inaccuracies. Unfortunately, because you're allowed to retake the exams after a certain period passes, the correct answers are never revealed. One of the questions on this exam is the following:  Richard’s wife(A) Abigail(B) is an incredibly talented cook(C) and gardener. Comma at (A) Comma at (B) Comma at (C) Comma at (A) and (B) No commas needed  I answered "No commas needed", but I suspected afterwards that the answer key was looking for the answer choice above it, "Comma at (A) and (B)". After searching this question online, I found a website with answers for the various questions on the test, and the site claims that "Comma at (A) and (B)" is in fact the correct answer for this particular question. Is the answer key wrong? I feel like there's really no need for any commas, but on the other hand, the appositive Abigail isn't restrictive because it doesn't offer terribly "essential" information, suggesting it could be set off by commas.


How do you use the EM algorithm to calculate MLEs for a latent variable formulation of a zero inflated Poisson model?

The zero inflated Poisson regression model is defined for a sample $(y_1,\ldots,y_n)$ by $$ Y_i = \begin{cases} 0 & \text{with probability} \ p_i+(1-p_i)e^{-\lambda_i}\\ k & \text{with probability} \ (1-p_i)e^{-\lambda_i} \lambda_{i}^{k}/k! \end{cases}$$ and it further assumes that the parameters $\mathbf{\lambda} = (\lambda_1, \dots, \lambda_n)$ and $\textbf{p} = (p_1, \dots, p_n)$ satisfy   $$\eqalign{ \log(\mathbf{\lambda}) &= \textbf{B} \beta \\ \text{logit}(\textbf{p}) &= \log(\textbf{p}/(1-\textbf{p})) = \textbf{G} \mathbf{\gamma}. }$$  The corresponding log likelihood of the zero-inflated Poisson regression model is  $$\eqalign{ L(\gamma,\mathbf{\beta}; \mathbf{y}) &= \sum_{y_i=0} \log(e^{G_i \gamma}+\exp(-e^{\textbf{B}_i \mathbf{\beta}})) +\sum_{y_i >0} (y_i \textbf{B}_i \mathbf{\beta}-e^{\textbf{B}_i \mathbf{\beta}})\\ &\quad -\sum_{i=1}^{n} \log(1+e^{G_{i} \gamma})-\sum_{y_i >0} \log(y_{i}!)}$$  Here, $\mathrm{B}$ and $\mathrm{G}$ are the design matrices. These matrices could be the same, depending on the features one desires to use for the two generating processes. They have the same number of rows, however.  Assuming that we could observe $Z_i = 1$ when $Y_i$ is from the perfect, zero state and $Z_i = 0$ when $Y_i$ is from the Poisson state the log-likelihood would be   $$L(\gamma,\mathbf{\beta}; \mathbf{y}, \mathbf{z}) = \sum_{i=1}^{n} \log(f(z_i|\mathbf{\gamma}))+\sum_{i=1}^{n} \log(f(y_i|z_i, \mathbf{\beta}))$$  $$ = \sum_{i=1}^{n} z_{i} (\textbf{G}_i \gamma-\log(1+e^{G_{i} \gamma}))+ -\sum_{i=1}^{n} (1-z_{i})\log(1+e^{G_{i} \gamma})+ \sum_{i=1}^{n} (1-z_i)[y_{i} \textbf{B}_i \beta-e^{\textbf{B}_i \beta} - \log(y_{i}!)]$$ The first two terms are the loss in a logistic regression to separate $z_i=0$ from $z_i=1$. The second term is a regression to the points generated by the Poisson process.  But aren't latent variables unobservable? The purpose is to maximize the first log-likelihood. But we have to introduce latent variables and derive a new log-likelihood. Then using the EM algorithm, we can maximize the second log-likelihood. But this assumes that we know that either $Z_i = 0$ or $Z_i = 1$?


Windows 7 booting fail with error code 0xc0000225

I have an HP laptop Pavilion DV4. Last night, I installed Ubuntu and there was an problem about partitioning the hard disk, and I think I deleted the Windows boot record.  I didn't burn a recovery disc but there is built-in recovery partition on the hard disk.  All I want to do is to perform a Factory Restore but I need recovery disc. I could burn that disc from the recovery partition using HP recovery manager, but can't burn now. I can't also boot HP recovery manager using F11 key, because it has the same boot error.  I want to boot Windows 7 and want to burn recovery disc. How can I boot into my old windows 7. If I can boot it, I can burn Recovery Disc and I will make Factory Restore if it's needed.  I didn't make any changes to windows 7 partition but I did a problem about Boot Record.  There is a system partition on hard disk with the size of about 200 MB.There is BOOT folder too.  Installation of Ubuntu also failed, so I'm booting from Live Ubuntu USB.


How to compute the integral $\int^{\pi/2}_0\ln(1+\tan\theta)d\theta$?

How to compute the integral $\int^{\pi/2}_0\ln(1+\tan\theta)d\theta$. If we let $t=\tan\theta$, then the integral becomes to  $$\int^{\pi/2}_0\ln(1+\tan\theta)d\theta=\int_0^\infty\frac{\ln(1+t)}{1+t^2}dt$$.  Can we calculate this integral explicitly?


Saracino Ex 3.17: Associative binary operation with unique right identity, left inverse implies group

Suppose $G$ is a set and $\star$ is an associative binary operation on $G$ such that there is a unique right identity element and every element has a left inverse. Prove that $(G,\star)$ is a group. Here's my work so far: We know there is a unique $e \in G$ such that $x \star e = x$ for all $x \in G$. We also know that for each $x \in G$ there exists some $x^{-1} \in G$ such that $x^{-1} \star x = e$. My trouble is with establishing that $e$ is also a left identity element. If I can show that $e \star x = x \star e = x$ for all $x$, then I am able to prove that $x \star x^{-1} = x^{-1} \star x = e$ for all $x \in G$ with the following argument: \begin{align*}     x \star e = x \implies (x \star e) \star x^{-1} &= x \star x^{-1} && \text{Multiplying by } x^{-1} \text{ on the right} \\[3pt]     \implies (x \star e) \star x^{-1} &= e  && \text{(Defn. of inverse)} \\[3pt]     \implies (e \star x) \star x^{-1} &= e && (\text{Assuming } x \star e = e \star x) \\[3pt]     \implies e \star ( x \star x^{-1}) &= e && \text{(Associativity)} \\[3pt]     \implies x \star x^{-1} &= e && (e \text{ is the unique right identity element}).  \end{align*} My attempts at showing that $e$ is a left identity have been fruitless...I know I somehow must use the fact that $e$ is a unique right identity element because the text explained that without the uniqueness condition, $(G,\star)$ is not a group. Any help would be appreciated!


Used Air Drop to move a folder with mp3 files in it to my phone. Where are they now?

I moved some mp3s to my iPhone using AirDrop expecting they would be available in the Music app, but I can't seem to find them. Where can I find them on my phone?  There was no error or anything saying the files didn't go through. It appears as if they have been copied to my phone.


comparison of truncate vs delete in mysql/sqlserver

One thing struck in my head about mysql/sqlserver i.e delete/ truncate  Which one is better and faster ?  where to use delete?  where to use truncate?


Can I export a jpeg or something similar?

I am very new to blender and am really excited to have found this amazing world of Blender and all of its beautiful people and possibilities. I am trying to capture an image of my projects to record and share progress. Can I export a simple jpeg or something similar? Or do I need to take a screenshot? And can that be done within Blender?   Thanks for your time And Answers... and possibly a better solution to my query.


Reference request: product Borel $\sigma$-algebra of non-separable metric spaces

The following is a proposition in Folland's Real Analysis about product sigma algebra:    Here $\mathcal{B}_X$ denotes the Borel $\sigma$-algebra on $X$.      Could anyone come up with an example that    $$ \mathcal{B}_X\setminus\otimes_{1}^n\mathcal{B}_{X_j} $$   is nonempty?


Here is the algorithm of insertion sort in C++ (from tutorial):  void insertionSort(int arr[], int length) {       int i, j, tmp;       for (i = 1; i < length; i++) {             j = i;             while (j > 0 && arr[j - 1] > arr[j]) {                   tmp = arr[j];                   arr[j] = arr[j - 1];                   arr[j - 1] = tmp;                   j--;             }       } }   and here is what I'm doing in Ruby  a = [12, 1, 18, -3, -2, 66, 31] puts a  def insertion_sort(source)     source.to_enum.with_index(1).each do |item, i|         j = i         while((j>0) && (source[j-1] > source[j]))             source[j], source[j-1] = source[j-1], source[j]             j -= 1           end     end end  insertion_sort(a) puts a   it throws an error of comparison of Fixnum with nil failed (ArgumentError). Probably because of overflow.  What did I do wrong?


Regular expressions in Groovy - extract part before first underscore only

Given is a string variable elementOne.   def elemenOne = 'AB_CD_EF_GH'   The challenge is to extract only the 'AB', the first part of its value, only that which precedes the first underscore symbol (counted from the left to right).  I have written a code:  def elementTwo = (element_one =~ /^.*(?=(_))/)[0][0]   but it extracts 'AB_CD_EF' instead of only 'AB'.  How should I modify my code, in order to extract only 'AB' part from 'AB_CD_EF_GH'?  Thank you!


Can't read directory from owner with 700 permissions

I have directory with rwx permission for current user, but he's unable to access it, why?  : sudo ls /usr/data/user-data  -lad drwx------ 9 andrew andrew 4096 May 17 11:13 /usr/data/user-data  : whoami  andrew  : ls /usr/data/user-data  ls: cannot access '/usr/data/user-data': Permission denied  : touch /usr/data/user-data/test touch: cannot touch '/usr/data/user-data/test': Permission denied   EDIT:  : sudo namei -lx /usr/data/user-data [sudo] password for andrew:  f: /usr/data/user-data Drwxr-xr-x root   root   / drwxr-xr-x root   root   usr drwxr--r-- root   root   data drwx------ andrew andrew user-data


I am building a network of Raspberry Pi  receivers.  Several nodes placed at different locations: home, lodge, parents, maybe more to come... They are all set up to  to an  using a reverse ssh tunnel.  What I really want to achieve is some way of distinction of which node is which and what local port to use for SSH to the node.  Since sudo netstat -tlpe --numeric-ports | grep sshd show what users is running the process I am thinking to have one user for each tunnel.  I want to restrict the users for SSH reverse tunnel only. Preferably I want to keep all node (multiple) keys in the same authorized_keys file and keep StrictModes yes for all other users.  I ended up running theese commands:  sudo groupadd sshtungrp sudo useradd sshtunnel -m -d /home/sshtunnel -s /bin/true -g sshtungrp while read p; do sudo useradd $p -M -d /home/sshtunnel -s /bin/true -g sshtungrp; done < users.txt;  sudo -u sshtunnel mkdir /home/sshtunnel/.ssh sudo -u sshtunnel vim /home/sshtunnel/.ssh/authorized_keys  sudo -u sshtunnel chmod 750 /home/sshtunnel sudo -u sshtunnel chmod 750 /home/sshtunnel/.ssh sudo -u sshtunnel chmod 640 /home/sshtunnel/.ssh/authorized_keys   To /etc/ssh/sshd_config I've added:  Match Group *,!sshtungrp         StrictModes yes   And I get the error message Directive 'StrictModes' is not allowed within a Match block.  How may I overcome this or otherwise end up achieving my goal of knowing which node is which and what local port to use for SSH to the node?


Can this set exists $\{\{\{\ldots\}\}\}$?

I know from the axiom of regularity that the set $\{\{\{\ldots\}\}\}$ cannot exist in ZFC.  Is there another set theory where it's possible ? If yes, how would we construct it ?


QGIS Python - Convert the CRS of an in memory vector layer

In a python script of qgis I load layers from different datasources using the QgsVectorLayer() and  the QgsRasterLayer() commands. The coordinate reference systems of the data sources differs. Since I have for some sources only the permission to read, I cannot transfrom the CRS of the datasource. Thus, i have to change the CRS from old CRS into new CRS in the in memory layer. What is the way to do it, e.g. to get an extent() in the new coordinates?


What is the closed formula for finding      $$ \sum_{i=0}^{k} \binom{n}{2i}=?\quad ,k\leq \lfloor{n/2}\rfloor $$   I need summation only up to some intermediate  $k$ where $k\leq \lfloor{n/2}\rfloor$ .  SAY I need a closed formula to calculate $\binom{8}{0}+ \binom{8}{2}+\binom{8}{4} +\binom{8}{6}$  HERE $n=8$ and $k=6$


pgfplots: Changing horizontal spacing in the legend

I'm drawing a simple scatter plot with pgfplots, which also includes a legend as shown in the upper part of the picture next.    However, I find the horizontal spacing odd because the distance between the symbol and the corresponding description is the same as to the next description. I would like to have it like "faked" in the lower part of the picture.  A simple example is produced by the following code. Here, the descriptions are a,b,c,d.  \documentclass{scrartcl} \usepackage{pgfplots} \begin{document}  \begin{tikzpicture}     \begin{axis}[legend columns=-1, legend pos=outer north east]         \addplot+ coordinates {(0,0) (0,1)};         \addplot+ coordinates {(1,0) (0,0)};         \addplot+ coordinates {(0,0) (1,1)};         \addplot+ coordinates {(1,1) (0,0)};         \legend{a,b,c,d};     \end{axis} \end{tikzpicture}  \end{document}   If I understand the manual correctly, the legend is composed of a matrix. However, I could not figure out how to change the spacing accordingly. Your help is much appreciated ;)


After upgrading to Fedora 18, I am seeing the following critical messages on /var/log/messages whenever I log on to the computer:  CRITICAL: gsm_manager_set_phase: assertion \`GSM_IS_MANAGER<br> Gtk-CRITICAL: gtk_main_quit: assertion `main_loops != NULL' failed   Based on my limited knowledge, critical messages and above can affect the usage of my computer if I don't deal with these urgently. Not that they are affecting the current usage of my computer, but I would like to find out more about them (seems to deal with mobile technology and GIMP toolkit?) and how to turn them off if I do not need these services.


$f$ is continuous and open implies $f$ injective

Question:  Let $f: \mathbb R \to \mathbb R$ be continuous and open, that is if $A \subset \mathbb R$ is open then $f(A) \subset \mathbb R$ is open. Prove that $f$ is injective.   Attempt:  Suppose $f$ is not injective then there exit $x, y \in \mathbb R$ such that $$x < y \implies f(x) = f(y) = c$$  Take the closed inteval $[x,y] \subset \mathbb R$, as $f$ is continuous then $\displaystyle {f|_{[x,y]}}$ is continuous, by Weierstrass Theorem we have that $f$ has a maximum or a minimum point.   Let's assume $m = \max \{f(a) ; a \in [x,y]\}$. Now there is  $x' \in [x,y]$ such that $f(x') = m$. If we take the open $(x'-\delta, x'+\delta)$ centered at $x'$ and  we have  (1)  If $m = c$ then $f$ is constant on the interval $[x,y]$ and $f((x'-\delta, x'+\delta)) = \{c\}$ which is closed, thus a contradiction;   (2)  If $m \neq c$ then we would have $f((x'-\delta,  x'+\delta)) = (b, m]$, where $b$ can also be $b = \infty$. Again a contradiction.   Well, this is my least embarassing attempt. I'm not sure how to show $(2)$ $100 \%$.   I have also tried to show $f^{-1}f(A) = A$ for any $A \subset \mathbb R$, tried to work on the connected space  $\mathbb R$ by finding a contradiction using the intervals $E_{[f > c]}$ and  $E_{[f < c]}$ open when $A$ is open.   Any thoughts?  Note: I've already seen  to try something out, but the fact that $f$ is monotone on this exercise comes as a consequence.


Why can the Euler beta function be interpreted as a scattering amplitude?

The  claims that the  can be interpretted as a scattering amplitude. Why is this?  In another word, when the  Euler beta function is interpreted as a scattering amplitude, what features does it have that make it able to explain strong force of ?  What properties of (or why) the Euler beta function (when interpreted as scattering amplitude) has string behavior?


If I try to open Files nothing happens except a spinny icon and my computer fans running fast.  If I run xdg-open . then I get Failed to register: Timeout was reached  I've attempted to google but couldn't figure it out. No logs were written to dmesg or /var/log/syslog  Ubuntu 18.04  Edit: Running sudo xdg-open . works but is not ideal as I'd be editing the files as root.


Back in the day, I remember having an e-mail program (perhaps it was Eudora?) that could schedule the sending of mail, so when composing a message, you could set some preference for when it would be sent. The message would be composed and queued up, but would not send until the computer was connected to the internet at or after the schedule time.  Is there a way to duplicate this feature in Apple Mail? Specifically, I want to compose a message, but rather than clicking "Send", I click "Delayed send" (either from the Services menu, the AppleScript menu, or, ideally, from an icon magically added to the Mail toolbar, but I don't expect that will be easy to pull ofF). When I do this, I'd get a dialog box asking me when I want to send the message. I enter the information, and the message is queued up and will be sent at the soonest time after the scheduled send time/date when the computer is on and connected.


I made a small app in android studio, which is tic tac (XO) game. All was working fine and I've tested the app on the emulator many times. But at a moment the application crashed and the well known message says: Unfortunately, "tictactoe has stopped". And then I wasn't even able to start the app, all the time it crashes when trying to run it.   Android logcat showed those messages:     E/AndroidRuntime: FATAL EXCEPTION: main      E/AndroidRuntime: java.lang.RuntimeException: Unable to resume activity {.tictactoe/.tictactoe.MainGame}: java.lang.NullPointerException     E/AndroidRuntime:     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2575)      E/AndroidRuntime:     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)      E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)      E/AndroidRuntime:   at android.app.ActivityThread.access$600(ActivityThread.java:130)   With many more messages. Any help?  Update: more logcat:     E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)      E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99)      E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137)


Why does this question have 26 "entered HNQ" revision entries?

I answered a question on Science Fiction & Fantasy Stack Exchange, which I noticed had gotten a relatively large amount of votes. I figured it had probably gone HNQ, and went to check the  (spoilers for Harry Potter and the Half-Blood Prince, BTW). I found out that boy yeah it had gone HNQ:  All in all, there were 26 entries for "Became Hot Network Question" in the post revision history. Which... seems odd, since I'm pretty sure there's only supposed to be . This seems like a bug; there probably shouldn't be 26 different entries for a question hitting HNQ.


Lost Administrator Password for Windows 2003 R2 Enterprise Server

I am trying get an unused server up and running, it booted fine but i was greeted with the login window and none of the known passwords seem to work. The server I am trying to get to work is not a Domain Controller and has not been used in a long time.  OS: Windows 2003 Server R2 Enterprise Edition  I tried Ophcrack XP (there is no WinServer version of Ophcrack) - it couldn't locate the partitions with hashes. I tried mounting the partitions myself (#mount /dev/hda*x* /mnt/ntfs), but it gave me an error saying /dev/hda*x* didn't exist.  Next I tried booting into a Ubuntu 10.04.3 LiveCD so that I could install and use chntpw - no go, Ubuntu Live wouldn't boot.  Based on what I've read up the following tools may be of help:   Windows Password recovery Petter Nordahl-Hagen's Offline NT Password & Registry Editor Openwall's John the Ripper EBCD – Emergency Boot CD - Bootable CD (R)ecovery (I)s (P)ossible Linux rescue system   I am hoping that someone here has prior experience with Win2k3 Administrator password resets so that I don't end up having to try all of the above to find out which one works.


I have a polygon layer. I extracted the coordinates of vertices, and now I need to add these coordinates in each polygon. The final shapefile should have an attribute table as follows:    where X1, X2, etc.. are the vertices coordinates for each polygon.  Any ideas on how to do this using ArcGIS for Desktop?


90s space novel or short-story series about synergy of knowledge

I'm trying to remember a book where generalization of knowledge was mentioned in every chapter at least once.   The book contained either a series of short stories with the same protagonists, either a novel in which each chapter was devoted to a specific, stand-alone situation. There might have been an overarching plot, but the book had a distinct "Sherlock Holmes solves one case after another"-feel.  IIRC, the book was set on a spaceship, traveling between planets. It had a crew of scientists, each of whom was an expert in their respective field. Every time the crew would get in trouble, the protagonist would find a solution. The main identifying detail (and the leitmotif for the whole book) was that the protagonist was a polymath with an extensive knowledge in multiple, largely unrelated subjects. Despite other people being more knowledgeable or skillful in something, "Sherlock" would always be the one with the right answer, because he was able to integrate expertise from many domains. Synergy/Integration of knowledge was repeatedly hailed as the only way to survive in the future.   I read it in the mid- to late 90s, so I'm assuming it's from the early 1990s, but it might be actually older.


How many bits of symmetric security does RSA-3072 actually provide?

I know that the sizes are standardized to $1024$, $2048$ etc. but they actually provide different security than $128$, $256$... for example $\texttt{RSA-}2048$ is actually $112$ bits of security and $128$ bits would be $2304$, so how many bits of security is $\texttt{RSA-}3072$ actually providing?


In which language did attributes first appear

It seems that almost all features in C# were borrowed from another languages (OOP from Java, generics (parametric polymorphism) and lambdas from ML family, LINQ from Haskell's monads and dynamic from dynamic languages), but I don't know the origin of attributes(annotations in Java world). Is C# the first language that introduced attributes?


Are submodules of finitely generated free modules always free?

I don't believe it's true that all submodules of a finitely generated free module are free just based on results from google. Is there a canonical simple example of a finitely generated free module with a submodule that is not free?


I need to plot the Bessel functions of first and second kind (J and Y), and the modified Bessel functions of first and second kind (I and K), with integer order, from order 0 to order 5, using pgfplots. Several solutions have been already presented in other questions, but:  Gnuplot makes available for plots only the Bessel functions of the first and second kind and only of order 0 and 1, so  is not suitable. I would not like to use nor pstricks, neither LuaTeX, so also  and  are not suitable.  is quite similar, but has no answer and no examples in the comments.  How to accomplish this with pgfplots? Also an external solution with numpy, scipy and Matplotlib as in  would be ok (however, the code seems to work only for the J function).    I tried using the code in the last linked , inserting as an \addplot the file example-04.txt. It works for the function J, but it prints unacceptable values (e+09) for function Y, which is very large and negative near 0. The code which generates example-04.txt is Python and here it would be almost certainly OT.


What is the proposed penalty for students that paid an essaywriting service to complete their papers for them?

I had noticed a sudden change in the quality of the essays submitted two of my students. When I confronted them, they were quite frank and admitted that due to lack of time, they had assigned their papers to be written by an outside source, an essaywriting service (a booming business that must be).   What is the proposed penalty?   If I take this on an administrative level, they face a pause of educational activities for 6 months to 1 year. But since this is the first incident, I do want them to learn their lesson, but at the same time taking into account that they were honest with me, not being punished too hard.  What do you propose? Is there something I can do to keep this from an administrative level and at the same time punish them?


Well, obviously billions of years if it is the moon. Or not very long if it is only 100km above the Earth, due to atmospheric drag. Also, how long it stays up would depend on density ie how much energy it has to dissipate in order to lose speed to drag due to mass/cross sectional area.  However, somewhere in the middle we have satellites that will stay up for... how long? How long will geo-sync satellites remain in orbit? What forces are exerted on them that will affect their stay eg magnetic field effects, solar wind etc? If we wanted to put a satellite in orbit and keep it there (say) 10,000 years how close could we get to Earth before this became unrealistic?


I'm trying to get my head round the following calculation of the fundamental group of the torus, using Seifert Van-Kampen (I know it's easier to do this by considering covering spaces, but I'm trying to learn the Seifert Van-Kampen method).   Consider the torus $T$ as the unit square in $\mathbb R^2$ with opposite edges identified. Let $A$ be an open disc (say of radius $1/4$ about the origin), and $\overline{A}$ be it's closure. Let $B$ be complement of $A$, so that $A \cap B = S^1$. Then we have $T = A \cup B$ where $A$ and $B$ are a neighbourhood deformation retract pair, so we can use Van Kampen. It is clear that $\pi_1(A) = \{e \}$ and $\pi_1(A \cap B) = \mathbb Z$. So we need to find $\pi_1(B)$. Observe that $B$ deformation retracts onto the boundary of the square which, after identification, is homeomorphic to $S^1 \vee S^1$; in this way we see that $B$ and $S^1 \vee S^1$ are homotopy equivalent (inclusion in one direction, the retraction in another), and so $\pi(S^1 \vee S^1) = F_2$ (which can be calculated by Van Kampen, or by using the theory of covering spaces). So, by Van Kampen, $\pi_1(T) \cong F_2 *_{\mathbb Z} \{e\}$. This is the quotient of $F_2$ by the normal closure of the image of $l_* : \pi_1(A \cap B) \to \pi_1(B)$ (where $l_*$ is the homomorphism induced from the inclusion map $l : A \cap B \hookrightarrow B$). The following is causing me confusion: The generator of $\pi_1(A \cap B)$ is homotopic in $B$ to a loop of the form $u.v.\overline{u}.\overline{v}$, where $u$ and $v$ represent the two generators of $F_2$. So $\pi_1(T) \cong \langle a,b ; aba^{-1}b^{-1} \rangle$, the free abelian group on two generators.  Any explanation or geometric intuition would be really appreciated. Thanks


TikZ: draw objects in transparent objects (3d)

I want to draw a cuboid in another transparent cuboid with TikZ. Therefore I've created a \newcommand to draw a cuboid.  \documentclass[11pt, halfparskip]{scrartcl} \usepackage{ucs} \usepackage[utf8x]{inputenc} \usepackage{tikz}  \begin{document} \newcommand{\cuboid}[7]{     % bottom     \draw[#7] (#1, #2, #3) -- ++(#4, 0, 0) -- ++(0, 0, #6) -- ++(-#4, 0, 0) -- cycle;     % back     \draw[#7] (#1, #2, #3) -- ++(#4, 0, 0) -- ++(0, #5, 0) -- ++(-#4, 0, 0) -- cycle;     % left     \draw[#7] (#1, #2, #3) -- ++(0, 0, #6) -- ++(0, #5, 0) -- ++(0, 0, -#6) -- cycle;     % right     \draw[#7] (#1+#4, #2, #3) -- ++(0, 0, #6) -- ++(0, #5, 0) -- ++(0, 0, -#6) -- cycle;     % front     \draw[#7] (#1, #2, #3+#6) -- ++(#4, 0, 0) -- ++(0, #5, 0) -- ++(-#4, 0, 0) -- cycle;     % top     \draw[#7] (#1, #2+#5, #3) -- ++(#4, 0, 0) -- ++(0, 0, #6) -- ++(-#4, 0, 0) -- cycle; } \begin{tikzpicture}   \tikzstyle{bottomfill} = [thick, fill=lightgray, fill opacity=.5] \tikzstyle{camerafill} = [thick, fill=blue!20]  \cuboid{0}{0}{0}{4}{4}{4}{bottomfill} \cuboid{1}{1}{1}{1}{1}{1}{camerafill}  \draw[->, thick] (2, 1.5, 1.5) -- ++(4, 0, 0);  \end{tikzpicture} \end{document}   But the result looks strange (The inner cuboid seems to be outside the transparent cuboid; compare the cuboid and and the arrow of the second image)    The result looks right if I'm adding the planes in the right z-order (but that's exhausting)  \documentclass[11pt, halfparskip]{scrartcl} \usepackage{ucs} \usepackage[utf8x]{inputenc} \usepackage{tikz}  \begin{document} \begin{tikzpicture} \tikzstyle{bottomfill} = [thick, fill=lightgray, fill opacity=.5] \tikzstyle{camerafill} = [thick, fill=blue!20]  % 1 bottom \draw[bottomfill] (0, 0, 0) -- ++(4, 0, 0) -- ++(0, 0, 4) -- ++(-4, 0, 0) -- cycle; % 1 back \draw[bottomfill] (0, 0, 0) -- ++(4, 0, 0) -- ++(0, 4, 0) -- ++(-4, 0, 0) -- cycle; % 1 left \draw[bottomfill] (0, 0, 0) -- ++(0, 0, 4) -- ++(0, 4, 0) -- ++(0, 0, -4) -- cycle;  % 2 bottom \draw[camerafill] (1, 1, 1) -- ++(1, 0, 0) -- ++(0, 0, 1) -- ++(-1, 0, 0) -- cycle; % 2 back \draw[camerafill] (1, 1, 1) -- ++(1, 0, 0) -- ++(0, 1, 0) -- ++(-1, 0, 0) -- cycle; % 2 left \draw[camerafill] (1, 1, 1) -- ++(0, 0, 1) -- ++(0, 1, 0) -- ++(0, 0, -1) -- cycle; % 2 right \draw[camerafill] (1+1, 1, 1) -- ++(0, 0, 1) -- ++(0, 1, 0) -- ++(0, 0, -1) -- cycle; % 2 front \draw[camerafill] (1, 1, 1+1) -- ++(1, 0, 0) -- ++(0, 1, 0) -- ++(-1, 0, 0) -- cycle; % 2 top \draw[camerafill] (1, 1+1, 1) -- ++(1, 0, 0) -- ++(0, 0, 1) -- ++(-1, 0, 0) -- cycle;  \draw[thick] (2, 1.5, 1.5) -- ++(2, 0, 0);  % 1 right \draw[bottomfill] (0+4, 0, 0) -- ++(0, 0, 4) -- ++(0, 4, 0) -- ++(0, 0, -4) -- cycle; % 1 front \draw[bottomfill] (0, 0, 0+4) -- ++(4, 0, 0) -- ++(0, 4, 0) -- ++(-4, 0, 0) -- cycle; % 1 top \draw[bottomfill] (0, 0+4, 0) -- ++(4, 0, 0) -- ++(0, 0, 4) -- ++(-4, 0, 0) -- cycle;  \draw[->, thick] (4, 1.5, 1.5) -- ++(2, 0, 0); \end{tikzpicture} \end{document}   With the result    My question: is there a possibility in TikZ to draw an object in a transparent object with without adding the shapes in the right z-order?


How can I block these windows that appear in web pages when scolling down?

I would like to know if it is possible to block these type of windows that appear when you scroll to the bottom of the web page or even when you just load them. It seems to me they are CSS. Generally they try to force you to subscribe to a newsletter or register to the website.  I use Firefox 36


Can I find a number, such that the its SHA-256 hash is all-0

I want to find a number, such that the result of its SHA-256 hash is all 0. I don't know if this number exists.


I keep getting this messages :  W:Failed to fetch gzip:/var/lib/apt/lists/partial/ph.archive.ubuntu.com_ubuntu_dists_trusty_multiverse_source_Sources  Hash Sum mismatch W:Failed to fetch gzip:/var/lib/apt/lists/partial/ph.archive.ubuntu.com_ubuntu_dists_trusty_universe_binary-i386_Packages  Hash Sum mismatch E:Some index files failed to download. They have been ignored, or old ones used instead.


I want to compile my program with the latest version of gcc.  Ubuntu 14.04 comes with gcc 4.8.2, however there's 4.9.0 available, moreover, I see that it is available as a package: . I tried to install it  sudo apt-get install gcc-4.9   but it says  Reading package lists... Done Building dependency tree        Reading state information... Done Note, selecting 'gcc-4.9-base' for regex 'gcc-4.9' gcc-4.9-base is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   Looks like it is already installed, just not as the default one? How do I utilize it to build my program?


The low quality queue doesn't believe I have enough rep to comment

When reviewing an answer in the low quality queue the question doesn't believe that I have enough reputation to comment.        I can't remember if commenting on the post not actually being reviewed was ever allowed?


2 orderby in wp_query with 2 custom fields

I'm triyng to display hotels (taxonomy which i have created) by two 'orderby' with wp_query but i'm not success.  Results looks likes:  Hotel 1 :       2 persons          5 stars Hotel 2 :       2 persons          4 stars Hotel 3 :       2 persons          3 stars Hotel 4 :       3 persons          5 stars Hotel 5 :       5 persons          5 stars Hotel 6:        10 persons         2 stars Hotel 7:        10 persons         1 star   The first 'order by' is on the number of persons(the biggest in first) and the second 'order by' is on the rating in stars (so, if several hotels have the same number of persons, the hotel with the biggest stars rating would be in first).  Below my code. I have tried to add an array inside an array with meta_query but it doesn't work.  $args=             array(                                     'post_type' => 'hotel',                                     'Services' => $Services,                                     'Town' => $Town,                                      'meta_key' => 'Number_persons',                                     'orderby' => 'meta_value_num',                                     'order' => 'ASC',                                        'meta_query' => array(                                                            array(                                                                'meta_key' => 'Rating',                                                                'orderby' => 'meta_value',                                                                'order' => 'DESC',                                                               )                                                        )                  );   $the_query = new WP_Query( $args );   Thanks a lot :)


Duo of alien xenologists study couple of Terran explorers, later save them

I once read a SF short story in the 80's, but I can't remember either the name nor the author. The protagonists are two alien anthropologists (one shaped like a tiger, the other like a dragon, I think) intent  on secretly studying two Terran explorers. The Terrans (dubbed "the big one" and "the small one") we soon learn are a couple and at one point they get in some kind of danger.  The two alien anthropologists decide to save them and manage to do so without revealing themselves, thus also "saving" their study.


18.04: How to get Wayland back after upgrade to 18.04?

Since 17.10 I got familiar with Wayland and I really need the per-monitor-scaling!  How can I start a wayland session after dist-upgrade to Bionic? There is no option in GDM available out-of-the-box.  I do not see what is described as     The Wayland session will still be available, pre-installed


Why put methods on the prototype of a class instead of declaring them in the constructor?

I'm trying to learn more about prototypal inheritance and I'm a little confused about the difference between adding methods to the prototype and adding them to the instance. Why would I do one over the other?  Prototype method:  function Foo() {} Foo.prototype.doBar = console.log.bind(console, 'Did bar!'); var foo = new Foo(); foo.doBar(); // prints "Did bar!"   Instance method:  function Foo() {   this.doBar = console.log.bind(console, 'Did bar!'); } var foo = new Foo(); foo.doBar(); // prints "Did bar!"   What is the advantage of putting my methods on the prototype? Is there ever a time when it makes more sense to declare the method on the instance via the constructor?


Let me give an example:  $ echo Hello > file1 $ echo Hello > file2 $ echo Hello > .file3 $ grep Hello * 2>/dev/null file1:Hello file2:Hello   Here you can see the grep ignored .file3 which is starting from .  Expected result:  $ grep Hello * 2>/dev/null .file3:Hello file1:Hello file2:Hello   In case of ls, there is an argument -a to tell do not ignore entries starting with . but I can't find any feature for grep  So, Is there anyway to tell grep do not ignore entries starting with .? or why grep ignores them?


A friend of mine came from Australia on the WVP and stayed 92 days. I made a mistake booking Her flight scheduling a Saturday arrival/departure at DFW. This amounted to a 92 day stay and with no funds to rebook a low cost flight through Qantas it was necessary to leave on the scheduled flight.   Question # 1) Was a automatic I-94W submitted by the airlines? She had no customs forms to fill out upon departure.   Question #2) How does this effect another WVP being issued if applied for?


When is the derivative of expectation the expectation of the derivative?

I am wondering what the conditions (if any) are for the derivative of an expectation to be equal to the expectation of a derivative: $$ \frac{d E[X(t)]}{dt} = E \left[\frac{dX(t)}{dt} \right] $$  where X(t) is some random variable.


I'm trying to align this 2 minipage on the top, but it doesn't work.....Any body help?  \documentclass{article} \usepackage{tikz} \usepackage{graphicx}  \begin{document} \begin{minipage}[t]{0.3\textwidth} $2+2=4$ \end{minipage} \begin{minipage}[t]{0.3\textwidth} \begin{tikzpicture} \draw (0,0) circle (3cm); \end{tikzpicture} \end{minipage} \end{document}   It gives me this:   I want this:   How can I get this???


What are my chances of getting a tourist visa to Croatia after 3 successive rejections?

First, I applied for a tourist visa for 16 days, showing a reservation for a hotel as I thought that visiting places nearby could be done in a single day. Also I showed my interest to meet friends I met online but didn't provide their details.  Result: visa refusal saying "Justification of purpose and conditions of the intended stay was not provided."  I required to reschedule my flight and changed the itinerary because of less time.  The second time, I applied right away for a tourist visa again for 9 days, showing a proper itinerary with different locations and different accommodation reservations. I added a letter to tell them about changes in the plan. I told them I wouldn't meet friends because my main purpose is tourism and I wouldn't have time to meet them.  Result: refusal with 3 points:  "proof of sufficient means of subsistence...".  "There are reasonable doubts as to the authenticity of the supporting documents or the veracity of their contents or the reliability of the statements made".  "There are reasonable doubts as to your intention to leave the territory of the republic of Croatia before the expiry of the visa applied for".  The third time, I applied again for a tourist visa with the same planning. And as I found that I didn't have movements in my savings account so may be it caused the issue. I added my salary account statements and other saving account statements. But I didn't have anything to prove my intention to leave the country other than my confirmed return flight, booking of final day accommodation. I thought the bank statement was issue for doubts on supporting document. So my new evidence will clear it.  Result: visa refusal with 2 points:  "There are reasonable doubts as to the authenticity of the supporting documents or the veracity of their contents or the reliability of the statements made".  "There are reasonable doubts as to your intention to leave the territory of the republic of Croatia before the expiry of the visa applied for".  After the third rejection I rescheduled my flights to next year. But still I am unable to find what the exact reason behind the refusal was. Recently I found that the company where I'm currently working was registered in February but I joined in January. So is it possible that they checked the company registration?  Can it be the reason of refusal of the visa application?  This year I am planning to go to a nearby country for my first international  trip. Will it be helpful for my next application? Can buying a car be evidence of property? Can having a fixed deposit of 4,000 USD be evidence of property?  How can I improve my circumstance before applying again?  I tried to contact several consultants but they even didn't answer after listening to my query.  Any help would be appreciated. Thank you.


Why does linear motion not emit gravitational waves?

Gravitational waves have been detected emanating from the decaying orbits of massive bodies, such as binary neutron star or black hole systems. To my understanding, two such bodies in what would otherwise be a stable orbit, will instead slowly radiate away their orbital momentum as gravitational waves and spiral inwards towards a merger. My question: if the circular motion of masses in spacetime can be lost as spiral gravitational waves, why can't the linear motion of masses in spacetime be lost as bow/wake shaped gravitational waves, as seen in ? I imagine the answer lies in the linear acceleration of masses compared to the linear inertial motion of them?


var legend=[{"min":0,             "max":first_color,             "color":"#1a9850"   },   {       "min":first_color,       "max":sec_color,       "color":"#fee08b"   },   {       "min":sec_color,       "max":thrd_color,       "color":"#ff3300"   },   {       "min":thrd_color,       "max":frth_color,       "color":"#d73027"       "Abc":"gsfg"   }    ];   I'd like to find out each object's property count. E.g. the first 3 objects have 3 properties and 4th one has 4 props, etc.


Application started by Udev rule closes after 4 seconds

File /etc/udev/rules.d/90-test.rules: ACTION=="add", SUBSYSTEM=="usb", ENV{DISPLAY}=":0", ENV{HOME}="/home/user", RUN+="/etc/udev/rules.d/test.sh"  File /etc/udev/rules.d/test.sh: #!/usr/bin/env bash /usr/bin/kcalc &  When I plug in an USB device, kcalc starts as expected (2 times because the rule is kept simple). But after 4 to 5 seconds, kcalc closes again. I also tried it with nohup but without success. Same occurs for other applications like konsole and kate. When I don't run kcalc in the background (no &), it doesn't close but it seems like further processing is blocked. The Device Notifier notifies me only after I closed kcalc. I dislike this solution because it affects other parts of the system. So why do the applications close and how can I prevent it?


Show the question nearby as you are typing your answer

When I'm answering a question, and my question is the 3rd or 4th answer, I can't see the original question while I'm typing.  I often scroll up to re-read some part of the original question.  Sometimes I even paste the question into the answer box as I'm typing, so that it will be right there for me to read.  I suggest that when answering, the position of the question and the answer edit box should always look the way it does for the very first person to answer a question- that is, the question should be directly above the editor.  Then after submitting an answer, it would fall to the bottom, just as it currently does.


Can I access the shrine near Kakariko village after completing the rest of the game?

I've done every possible quest in Kakariko. I am also unable to obtain the shrine ball through the event. Is it possible that I broke it due to me completing the game and ignoring that event? I didn't know it existed until now. I already know about the quests needed, I simply missed the event. I completed all Kakariko Side/Shrine Quests. I am at post-Endgame and accidentally ignored this event in my run. I've done the event on a different profile and it worked.


$(1+px+qx^2)^8 \equiv  1+8x+52x^2+kx^3...$  Given that expression, calculate the values of p, q, and k.  I'm guessing this is a trinomial that needs to be turned into a binomial, but how would you do it? I have no idea.


I am trying to create a table with specific cells coloured either green or red. As a trial, I used the following code to colour one cell green \documentclass[a4paper,12pt]{extarticle} %% Language and font encodings \usepackage[english]{babel} \usepackage[utf8x]{inputenc} \usepackage[T1]{fontenc}  %% Sets page size and margins \usepackage[a4paper,top=2.5cm,bottom=2.5cm,left=2.5cm,right=2.5cm,marginparwidth=1.75cm]{geometry}  \usepackage{amsmath} \usepackage{amsfonts}  \usepackage{amssymb} \usepackage{amsthm} \usepackage{mathtools} \usepackage{optidef}  \usepackage[framed,numbered,autolinebreaks,useliterate]{mcode} \usepackage[table]{xcolor}  \begin{document} \begin{table} \centering \begin{tabular}{ | l | l | l | }       \hline       A & B & C \\       \hline       D & E & \cellcolor{green}F \\       \hline       G & H & I \\       \hline \end{tabular} \end{table} \end{document}  Here I have used \usepackage[table]{xcolor}. This did not work, and the output generated is shown below  Is there a way to create a table with specific cell colours


Beside our internal IT infrastructure, we've got around 500 Linux machines hosting our services for the on-line world. They are grouped in a bunch of clusters like Database A-n, Product A-n, NFS, Backoffice and so on. Furthermore, they are administered by an external provider, according to our specifications and requirements.  However, we face a lot of trouble during (web-) software development, roll-out and deploy - especially because the dev- and staging-environments have almost nothing in common with the live systems (I spare out the nasty details..).  Thus, I've tried to create virtual machines, copied the various live-systems as exactly as possible and prepared them to connect to e.g. the development-databases instead of the "real" ones transparently for developers (they aren't root). This works pretty well, but...  I was wondering how one could administer those systems remotely and in bulk? Is there some software family I'm not aware of? Or, at least, some techniques or principles one should be familiar with?  We would provide every developer with a bunch of images to be run locally (VirtualBox). The QA dept. would get virtual clusters (XEN or Hyper-V). If I need to provide an additional server-module, re-route a new database connection or just want to update everything provided by the package manager... how could I possibly do that without being forced to log on to every system and/or ask my colleagues to download and run some fixture-script?  I believe there are plenty of solutions. Well, somehow I'm too stupid to enter the correct keywords into the search engines... Or isn't this issue as trivial as it sounds?  For the record:   Almost all systems are running Debian GNU/Linux 6.x "squeeze" No developer is forced to use a particular OS at his/her workstation The budget is limited, of course, but not too small to buy proprietary software A solution that would involve our aforementioned provider is preferred


I have got a NFC key to enter in my room and i want to make a copy of this key in case of loss. I read the nfc tag key with my nexus 5 with Broadcom BCM20793M NFC controller. The phone reads the tag and retrivies all the infos but when i try to copy the tag it gives an "Error reading the tag" message. The tag is a  NXP MIFARE Classic. I read that it is not compatible with the newest chips so i wanna buy an Arduino NFC reader to read and copy the tag.  Might it works?    Below all the infos retrieved from the nfc key:


ODE, change of form and unsolvable unknown

So I have tried many methods including Laplace transform and differentiation but the p and q seems to be unsolvable, I would like to know how does the form change from the first equation, then substitude the Y = e^t to get the second equation. also my second question is why is how can i solve for p and q if i dont have any initial conditions?


Is there a "canonical" probabilistic version of the step function?

Step and switch-like functions can be thought of as deterministic switches at some threshold, so smooth sigmoidal-like functions describe that switch with uncertainty around that value.  The machine learning literature discusses 'activation functions' extensively, but the choices are usually justified by application results. I am not aware of an argument for particular functions form first principles. The heaviside function is sometimes approximated by $H(x) \approx \frac{1}{2} + \frac{1}{2}tanh(rx)$, and I think the gaussian CDF has a more immediate probabilistic interpretation. Since probability distributions can be described as arising from idealized processes (e.g. gaussian from brownian motion, Gamma from sequence of exponential waiting times, binomial from repeated sampling with a fixed probability) my question is whether there is a canonical choice, or canonical choices depending on the process that generates the step function. EDIT The question is not whether there are continuous approximations to the step or Heaviside functions, nor whether there are functions that are popular or commonly used (so it's different from ) as an alternative to the discontinuous step. The question is whether there are functions that represent probabilistic switch-like behavior and arise naturally from probabilistic reasoning (if not in general, for specific processes that generate some sort of switch).


Prove $R\times S$ is not an integral domain

Let $R$ and $S$ be two commutative rings with unity. Prove that $R\times S$ is NOT an integral domain.   This is the best I could think of so far, please give me a push in the right direction and correct me.  It suffices to show that $R\times S$ has zero-divisors  Therefore, let $a$ be an element of $R$ and $b$ be an element of $S$, thus $R\times S$ has elements of the form $(a,b)$.  Consider the elements $A=(a,0)$ and $B=(0,b)$, such that $a$ does not equal zero and $b$ does not equal zero. Then $AB = 0$. Therefore $R\times S$ has zero divisors.


The minecarts are all broken. Seems like they are pretty useful for fast traveling between some places around the city, farm and mines.  How do I make these work?


As a very new researcher who is exploring the best way to generate ideas, some guidance on this question would be very helpful. I have found that this is NOT easy. Ideas seem to pop out of my Professor every day and I wonder how he does it. This question is broad;   How do you tend to come up with initial/seed ideas? What is your search method (if you have one)? What proportion of your ideas for past papers come from; (i) colleagues, (ii) intentionally browsing the literature for ideas, (iii) on the spot inspiration, (iv) conferences, (v) other? How do you prioritize research ideas? Is there any special, generalizable method that you've discovered to sift out those ideas that are likely to be unrealistic early on in the process of idea generation?   Based on small amounts of anecdotal evidence I have reason to believe that there is vast heterogeneity among professors regarding the above questions. For example, economist Steven Levitt says he works on 22 papers at once. A professor I know will have maybe 25% of this at any one time.  Related but not duplicate:


Finding out why my phone vibrates occasionally

Recently, my phone has started to vibrate shortly every few hours, as if to notify me of something. But when I check it, there aren't any (non-permanent) notifications. How to find out what/what app is causing this?


Unnamed/anonymous namespaces vs. static functions

A feature of C++ is the ability to create unnamed (anonymous) namespaces, like so:  namespace {     int cannotAccessOutsideThisFile() { ... } } // namespace   You would think that such a feature would be useless -- since you can't specify the name of the namespace, it's impossible to access anything within it from outside. But these unnamed namespaces are accessible within the file they're created in, as if you had an implicit using-clause to them.  My question is, why or when would this be preferable to using static functions? Or are they essentially two ways of doing the exact same thing?


Rendering shiny steel on a white background?

Even though there are several other questions with answers in this blog, I found the answers to my following question very useful. I want to render animations of a shiny type of steel, for example, the goal is having a rendering like this, but with a white background!  It seems the lighting, environment and HDRI are important, but I could not make it work! The result of my rendering is this picture:  Can you please have a look at this file and give any hints about any changes that I should do?  Thanks, Kind regards


How to justify unicyclic connected graphs formula?

I have read this formula in a book for $c(k,k)$, the number of unicyclic connected graphs on $k$ vertices , i.e. $n=m=k$.  How can one prove it? It seems that it is iterating on the length of the cycle. In addition how to prove the approximation?  $$c(k,k)=\sum_{r=3}^n {n\choose r}\frac{(r-1)!}{2}rk^{k-r-1} \sim \frac{\pi}8k^{k-0.5}$$


When i open an image the brushes are not there?

I was going to try to do the line art of one of my drawings on adobe illustrator, but when i open the file the brushes are not there. There's only the basic brush and i can't reduce its size. I've tried to open the image in various formats, but it didn't work. How can i solve this?


Need a Stack Exchange site for discussion about Hinduism

I think in this network (Stack Exchange) there should be a site for  Q&A about Hinduism! I saw two pages for Christianity and Islam. Hinduism is the third  largest religion and having 115cr+ followers. Then why not for Hinduism?


How can I cancel an edit I made on another user's question or answer?

Edits made by users who do not have edit privileges are placed in a queue until it is peer reviewed.  E.g., I edited someone else's answer. but changed my mind. If I'd edited my own question/answer, there would be a "Rollback" button, but there's no such button in the scenario I'm describing (at least none that I can see).  This is more relevant today because users can only have at most five edits waiting in the queue, and allowing one to cancel an edit would permit them to free up one of their five pending edits for something else.  Is there a way to remove one's edit from the peer review queue?


What is a good criterion or rule-of-thumb for determining when a control should be greyed-out and when should it be completely invisible?


Maxwell demon : how can the demon move the door without doing any work ?

Here is something that I never understood about Maxwell's demon paradox : in order to contradict the second law of thermodynamics, the demon must open and close the door without doing any work... But how is that possible ?   I know it is just a thought experiment but still, as I see it, it just shows (by contraposition) that, if you assume the second principle to hold true, then there cannot exist a device that will open and close the door in this way without doing any actual work (for instance, there will necessarily be some friction or whatever which will creates some work..)  Seeing things this way there is no paradox and it only states, as a corollary of the second law, that such a demon cannot exist...  Obviously, I am missing something here since there seems to be much more to this thought experiment than that... I would be extremely grateful if someone would take the time to explain to me where I am mistaken ! :)  Thanks !


Find all positive integers $m$ that satisfies: $a^2 \equiv 0\mod{m} \Rightarrow a \equiv 0 \mod{m}$, $\forall a \in \mathbb{Z}$

I could prove that this is statement is true if $m=1$ or if $m$ is prime.  However, I couldn't prove that the statement doesn't hold if $m>1$ is not prime.  Any hints?


Relationship between factors and exponents (cubic example)

This is a very basic question to illustrate an idea, but I'd be curious if I'm missing something. Let's say I have some positive natural numbers, $x,n,Q$ and I know the following: $x^3 = nQ$ and $x > Q$. Can we infer $x = fQ$, where $f$ is also a natural positive number? I'm not sure if there's a standard way to approach this, but my thoughts are this; we begin by not assuming $f$ a natural number, but note it must be a positive rational number. As it reduces to a positive number after multiplication by $Q$, then we express it as $f = P/Q$ where $P$ is also a positive natural number and $P>Q$. Then, we note $x^3 = (fQ)^3 = (P^3/Q^3)Q^3 = nQ$ and thus, $n = P^3/Q$. Now, if (P/Q) is a natural number, then we're done. But if not, then $P = mQ + a$, when $a$ is a natural number less than $Q$. It follows that $P^3/Q = n$ leaves a fractional term of $a^3/Q$, and thus the only way this can equate to a natural number is if $a=0$ and $f$ is a natural number. My two questions are (a) is this logic / proof outline correct, or am I missing something? and (b) Is there a clearer way to show this?


I came across the following statements $$\sum_{n=1}^{\infty} \frac{1}{n(2 n+1)}=2-2\ln 2 \qquad \tag{1}$$ $$\sum_{n=1}^{\infty} \frac{1}{n(3 n+1)}=3-\frac{3 \ln 3}{2}-\frac{\pi}{2 \sqrt{3}} \qquad \tag{2}$$ $$\sum_{n=1}^{\infty} \frac{1}{n(4 n+1)}=4-\frac{\pi}{2}-3 \ln 2 \qquad \tag{3}$$ $$\sum_{n=1}^{\infty} \frac{1}{n(6 n+1)}=6-\frac{\sqrt{3} \pi}{2}-\frac{3 \ln 3}{2}-2 \ln 2 \qquad \tag{3}$$ The (1) by partial fractions $$\sum_{n=1}^{\infty}\frac{1}{n(2n+1)}=\sum_{n=1}^{\infty}\frac{1}{n}-\frac{2}{2n+1}$$ $$=\sum_{n=1}^{\infty}\frac{1}{n}-\frac{1}{n+\frac{1}{2}}$$ Recall the Digamma function $$\psi(x+1)=\gamma+\sum_{n=1}^{\infty}\frac{1}{n}-\frac{1}{n+x}$$ Therefore $$\sum_{n=1}^{\infty}\frac{1}{n}-\frac{1}{n+\frac{1}{2}}=\psi(1+\frac{1}{2})-\gamma$$ $$\sum_{n=1}^{\infty}\frac{1}{n(2n+1)}=\psi\left(\frac{3}{2}\right)-\gamma$$ In the same token we can derive the relation for the other three ralations. My Question is: can we calculate the values of the digamma function for those values without resorting in the Gauss´s Digamma formula? $$\psi\left(\frac{r}{m}\right)=-\gamma-\ln (2 m)-\frac{\pi}{2} \cot \left(\frac{r \pi}{m}\right)+2 \sum_{n=1}^{\left\lfloor\frac{m-1}{2}\right\rfloor} \cos \left(\frac{2 \pi n r}{m}\right) \ln \sin \left(\frac{\pi n}{m}\right)$$  I tried this approach also, but I think the resulting integral is divergent $$\sum_{n=1}^{\infty} \frac{1}{n(2 n+1)}=\sum_{n=1}^{\infty} \frac{1}{n}\int_{0}^{1}x^{2n}dx=\int_{0}^{1}\sum_{n=1}^{\infty} \frac{x^{2n}}{n}=-\int_{0}^{1}\ln(1-x^2)dx $$


Seemingly I cannot update using the older IPSW files, only iOS 14. I have an iPhone 7 test device with iOS 12, and I only want to update to iOS 13 (iOS 13.7). Every attempt failed with basically the "not authorized" error. Tried with Finder, and iMazing. How can I update to only iOS 13 (without jailbreaking)?


"serverhit.com" seems to be a clone/scrapper of Ask Ubuntu

Website in question:   Screenshot of ServerHit:    First question on ServerHit is taken from Ask Ubuntu:    I have already utilized the contact form, however, I am additionally submitting here for visibility.


Can't create directory in etc for hadoop?

I am following . It says that     Unpack the downloaded Hadoop distribution. In the distribution, edit the file etc/hadoop/hadoop-env.sh to define some parameters as follows:   but when I open etc directory, I right-click to create a new directory inside. But "Create New Folder" option is disabled in context-menu. How can I create it?


Jumpy scrolling behavior using Chromium with my touchpad hardware buttons

I am experiencing very jumpy scrolling in Chromium. When use my touchpad hardware buttons to click anywhere on a page, and then use two fingers to scroll, the scrolling gesture will cause Chromium to jump to the top of the page and then start scrolling. This issue started about 1-2 months back. I have been hoping that it would be taken care of in an update, but that has not been the case.  I used Google Docs, xev and an external mouse to narrow down the behavior. It turns out that I cannot reproduce the event if I involve the external mouse in any way (touchpad click followed by external mouse scrolling or external mouse clicking followed by touchpad scrolling). I also can't reproduce the event when tapping the touchpad surface to emulate a click, it is only when I use any of the three physical touchpad buttons and then try to scroll with two fingers on the touchpad that the page jumps around.  When I used xev to monitor keystrokes, there is no even reported when I start dragging two fingers over the mousepad in a way that causes the page to jump. If I then continue to drag the two fingers, xev starts reporting the scroll event and the page also scrolls as normal.  I am using the synaptics drivers for the touchpad (xf86-input-synaptics 1.8.99.1-1) and I have been using these drivers previously without the problem. I did install the new libinput drivers and I do not see the problem with them, but they are introducing other problems, so I prefer the synaptics drivers. Chromium is the only application this is happening with. I am using Chromium 51.0.2704.103 (64-bit) on Antergos Linux (arch derivative), with Gnome 3.20.3 and kernel 4.6.3-1. My laptop is a Lenovo Yoga Thinkpad 12" 2nd Gen.  What can I do to resolve this issue?


Is it bad form to cross post to Stack Overflow and GitHub?

If I have a question about an open source project on GitHub, is it considered good or bad etiquette to open a new issue for that project on GitHub and post the same question on Stack Overflow (or other, appropriate SE site)?


How can I solve this limit: $\lim_{n\to \infty } \left(\frac{1}{1+n} + \frac{1}{2+n} + ... + \frac{1}{2n} \right) $?

how can I solve this?  $$\lim_{n\to \infty } \left(\frac{1}{1+n} + \frac{1}{2+n} + ... + \frac{1}{2n}  \right) $$  but the limit of this?  $$(x_n) = \frac{1}{\ln(n^2)} + \frac{1}{\ln(n^3)} + ... + \frac{1}{\ln(n^n)} $$  At the second sequence I tried  this:  $$ (x_n) = \frac{1}{\ln(n)}\Bigl(\frac{1}{2} + \frac{1}{3} + ... + \frac{1}{n}\Bigr)$$ That is indetermination $ 0\cdot \infty$ since the sum diverges, but I don't know how to continue.


I am passing data through a bean, but whenever I use the passed data in a if function it never passes the first check.  I will also post the result for just printing out the Get_Functions I am using.  The inputs I use are just admin and password.  JSP Code:  <jsp:useBean id="user" class="User.GetInfo" scope="session"/>  <HTML> <BODY> <% if (user.getUsername() == "admin") {     if (user.getPassword() == "password" ) {         session.setAttribute( "LoggedIn", true );         response.sendRedirect("AdminPage.jsp");      } else {         session.setAttribute( "LoginError", "Wrong password." );          response.sendRedirect("AdminLogin.jsp");     } } else {      session.setAttribute( "LoginError", "Wrong username." );      response.sendRedirect("AdminLogin.jsp"); } %> </BODY> </HTML>   Results for just printing out code:  You entered  Name: admin  Email: password


Difference between pointer to pointer and reference to pointer

These two function do exactly the same thing.  But in one the function argument is pointer to pointer and in the second it is reference to pointer.  1) Is there any difference between the two   2) when to choose which one.  #include <iostream>   using namespace std;   int global_var = 42;   // function to change pointer to pointer value  void changePointerValue(int** ptr_ptr)  {      *ptr_ptr = &global_var;  }   int main()  {      int var = 23;      int* pointer_to_var = &var;       cout << "Passing a pointer to a pointer to function " << endl;       cout << "Before :" << *pointer_to_var << endl; // display 23       changePointerValue(&pointer_to_var);       cout << "After :" << *pointer_to_var << endl; // display 42       return 0;  }   /////////////////////////////////////////////////////////////////////  #include <iostream>   using namespace std;   int gobal_var = 42;   // function to change Reference to pointer value  void changeReferenceValue(int*& pp)  {      pp = &gobal_var;  }   int main()  {      int var = 23;      int* ptr_to_var = &var;       cout << "Passing a Reference to a pointer to function" << endl;       cout << "Before :" << *ptr_to_var << endl; // display 23       changeReferenceValue(ptr_to_var);       cout << "After :" << *ptr_to_var << endl; // display 42       return 0;  }


What is the right way to join aluminum house wiring to aluminum fixture wiring?

My home is 1970s construction with aluminum wiring. I have recently upgraded several fixtures in my bathroom and basement. These fixtures have all been internally wired with stranded aluminum wiring. The directions for these fixtures make no mention of special care needed for joining aluminum to copper. About half of the fixtures have shipped with some sort of crimp connector to join to the house wiring, the remainder have shipped with bog standard wire nuts. These fixtures are all LED lights. I expect them to be fairly low draw.  I am well aware of the risks of AL wiring when adding fixtures and outlets. CO/ALR receptacles triple the cost of simple work in my home. I am well aware of the risks and needs of joining aluminum wiring to fixtures made for copper.  Do I need to take any special precautions when wiring aluminum to aluminum for these new fixtures?   Do AL to AL connections pose any risks distinct from AL to CU connections?


Can you ever use an ASI to increase an Ability Score above 20?

My question stems from this one:   How exactly does increasing an ability score above 20, by any means, work at all? Relevant quotes:  Ability Score Increases: Some of these features allow you to increase your ability scores, either increasing two scores by 1 each or increasing one score by 2. You can't increase an ability score above 20. -PHB pg. 15 Manual of Gainful Exercise: ...your Strength score increases by 2, as does your maximum for that score.  Say you have a Strength score of 18, and use a Manual of Gainful Exercise to increase it to 20, can you still not use an ASI to increase it to 22, despite the "maximum" now being 22? In fact, is 20 even the maximum for your ability score when using items; the quote seems to only apply to Class Features.


Why does this Java long calculation return NaN?

import java.util.*; import java.lang.*; import java.io.*;  public class MyClass {     public static void main (final String[] args) {         float distanceInMeters = 0.0f;         long time = 1439230171182L;         long previousTime = 1439230111554L;         float speed = (distanceInMeters / 1000) / ((time - previousTime)/3600000);         System.out.println(speed);     } }   This calculation returns "NaN". Does anyone know why?


SELECT within SELECT PDO prepared statement

I'm thinking of an example like this one:  The request hits a page at an url (by whichever means), with a parameter. example.com/api/page?name=bob. It's my understanding that you should do a prepared statement to get the $_POST[name]parameter and make sure it's not anything funky, but it does so by evaluating the expression.   My first question is: How does it do so (evaluate the expression)?  My second question is:  What if a user inputs something along the lines of "SELECT * FROM users" or "DROP TABLE users" that gets passed to the $_POST['name'] parameter (the ?name=bob at the end), what would happen in that case?  Just as an example, the final query would be something like   SELECT name, continent FROM world WHERE continent IN (SELECT continent FROM world WHERE name='Brazil')   the second select acting as the user input parameter - so $_POST['name'] contains this query SELECT continent FROM world WHERE name='Brazil'  Lastly, the third question i have is how can i protect against something like that?   I'm guessing PDO is design specifically to prevent query within query(?), but after reading around a bit i'm still quite confused.  I'm still learning all of this so if i'm not clear or specific enough in my inquiry please let me know, and i'll try and address that.  EDIT: To clear any confusion, what i'm doing is this:  $pdo = new PDO('..'); $sql = 'SELECT id FROM users WHERE username = :username'; $statement = $pdo->prepare($sql); $statement->bindParam(':username', $_POST['username']);   Question is, what if $_POST['username'] contains 'SELECT * FROM users' (or any other query) ? How does prepare() work? Can what i described actually present a security hole? I need some help in understanding this.


Can I withdraw Roth 401k contributions penalty-free before age 59.5?

I know that with a Roth IRA, contributions can be withdrawn penalty-free at any time. If I rollover a Roth 401k into a Roth IRA, can I do the same with the contributions made to the Roth 401k?   I've  that the entire Roth 401k->Roth IRA rollover counts for penalty-free/tax-free early withdrawal, but that sounds too good to be true.


Changing TOC to include figure and table and fancy header

How can I change the TOC to display Figure: X and Table X? Also if you notice in the header there is a somewhat fancy header with the name and a horizontal line, I would like to get that too.  I currently have like this like.   And I want to make it look like this.    Can someone help me?


random forests variable importance plot - interpretation in R (VarImpPlot)

I have constructed two variable importance plots in r using random forests regression the dependent variable is wheat yield and the independent variables are topographic and vegetative parameters. I am wanting to know which topographic/vegetative variables have the most importance influence on wheat yield. I have done this for two years of data.  The variable importance plot is shown below for both years.  How do I interpret this? the node purity for the two years is different?  Also, how do I know which plot is most accurate?  The variation explained in 2015 is 70%. while the variation explained in 2016 is 40% (the graph for 2016 looks more accurate though?) - please correct me if I am mistaken.  library(randomForest) rf1 <- randomForest(Yield_2015~TWI +Upslope_length+ Curvature + Aspect+Slope+NDVI_2015+SAVI_2015,                 data=Topo_yield) rf1$importance varImpPlot(rf1,main="Important variables for Yield 2015") rf2 <- randomForest(Yield_2016~TWI +Upslope_length+ Curvature + Aspect+Slope+NDVI_2016+SAVI_2016,                 data=Topo_yield_16) varImpPlot(rf2,main="Important variables for Yield 2016")


Python inheritance with dictionary mutation

I'm curious on how inheritance works in case of dictionary mutations, I always thought that with each new instance the inherited classes get recreated.  class A(object):     test = {"B": 0}      def change_test(self, index):         self.test["B"] += index      def __init__(self, **kwargs):         self.change_test(self.index)         super(A, self).__init__(**kwargs)   class B(A):     index = 1     def print_test(self):         print self.test   class C(A):     index = 2     def print_test(self):         print self.test  b = B() b.print_test()  c = C() c.print_test()   Why does this return {'B': 1} {'B': 3} and not {'B': 1} {'B': 2}?


Proving the divisibility of large numbers without making large calculations

How would you you show that $2^{32}+1$ is divisible by $641$ without making large calculations?


How do I echo a string with multiple spaces in bash "untouched"?

I assigned a var like this:  MYCUSTOMTAB='     '   But using it in echo both:  echo $MYCUSTOMTAB"blah blah"   or  echo -e $MYCUSTOMTAB"blah blah"   just returns a single space and the rest of the string:   blah blah   How can I print the full string untouched? I want to use it for have a custom indent because \t is too much wide for my tastes.


How to limit reverse SSH tunelling ports?

We have a public server which accepts SSH connections from multiple clients behind firewalls.   Each of these clients create a Reverse SSH tunnel by using the ssh -R command from their web servers at port 80 to our public server.  The destination port(at the client side) of the Reverse SSH Tunnel is 80 and the source port(at public server side) depends on the user. We are planning on maintaining a map of port addresses for each user.  For example, client A would tunnel their web server at port 80 to our port 8000; client B from 80 to 8001; client C from 80 to 8002.  Client A: ssh -R 8000:internal.webserver:80 clienta@publicserver  Client B: ssh -R 8001:internal.webserver:80 clientb@publicserver  Client C: ssh -R 8002:internal.webserver:80 clientc@publicserver   Basically, what we are trying to do is bind each user with a port and not allow them to tunnel to any other ports.   If we were using the forward tunneling feature of SSH with ssh -L, we could permit which port to be tunneled by using the permitopen=host:port configuration. However, there is no equivalent for reverse SSH tunnel.  Is there a way of restricting reverse tunneling ports per user?


How can I warm up my new LED recessed lighting

I was just buying some halogen replacement bulbs for my kitchen recessed lighting  when the salesperson talked me into buying recessed LEDs instead. The sales pitch was great about how long they last and energy efficiency. They look super cool too.....until you turn them on.  Then they have a really harsh, blue light as opposed to the beautiful warm glow of my halogens. I've read that you can use photo gels somehow, but I just need to know more details about how to actually install them.  Do you just sort of "fit" them into the opening?  Will they get too hot?  What color should I get?  Anybody have any ideas?


iPad Mini 1st Gen (Jailbroken), want to upgrade from 7.1.2 > 9.0.2, not 7.1.2 > 9.3.5, don't know where to start.

So I have an iPad Mini First Generation that is currently jailbroken using Pangu. It is currently on 7.1.2 and I want to upgrade it to 9.0.2, but not the latest, which is 9.3.5. I've heard about using BLOBs and unsigned IPSWs but I'm not sure what to do. Could someone shed some light on me?  Thanks!


Can a c# DateTime value be set to a specific invalid value (like double.NaN)?

I would like to initialize a DateTime value object with a value that does not represent a valid date because I need to distinguish an invalid or unset date from any valid value. For floating point numbers I would use not-a-number values like in this example:  Double value = Double.NaN;   Is there a similar value for DateTime objects in c#? For example something like that:  DateTime datval = DateTime.Invalid;


Complex structure on $\mathbb{C}\mathbb{P}^2\# \dots \# \mathbb{C}\mathbb{P}^2$

I know the chern classes-related theorem that states that $\mathbb{C}\mathbb{P}^2\# \dots \# \mathbb{C}\mathbb{P}^2$ ($k$ times) has no almost complex structure (hence no complex structure) if and only if $k$ is even.  I also know that $\mathbb{C}\mathbb{P}^2\# \mathbb{C}\mathbb{P}^2 \# \mathbb{C}\mathbb{P}^2$ has no complex structure, hence the almost complex ones you define on it are not integrable.  Where can I find a proof of this proposition? How do I see that the connected sum of three (or five, or seven, or every odd number) copies of $\mathbb{C}\mathbb{P}^2$ doesn't admit a complex structure?


Is my stepson being exposed to something inappropriate?

My step son is 5 years old and spends most of his time with his biological mom. We don't agree with a lot of the things she does but I have never though there was anything not good going on. However, a few weeks ago he was watching my hubby play a video game. He said he liked the girl characters boobs and that he wanted to put his wiener on them. More recently he told me that after his dad went to work he wanted me to pull my pants down and sit on his head. I feel like this is not normal for his age and I'm wondering if he is being exposed to something inappropriate at his mom's. Am I wrong? Is this normal for a 5 year old?


i'm facing the error please help me sort it out,as i have my project to be submitted....please...   import java.util.*;  public class project {          public static void intro1() {     Scanner obj= new Scanner((System.in));     System.out.println(" This converter will be related as follows" );     System.out.println(" 1.Digital Storage" );     System.out.println(" 2.Distance(length)" );     System.out.println(" 3.Currency" );     System.out.println(" 4.Temperature" );     System.out.println(" Please choose your option,which you want to be converted,please type that number related" );     int q= obj.nextInt();     System.out.println(" Command received!....executing..." );     String w=Integer.toString(q);     String a=(w.trim());     int n=Integer.parseInt(a);     switch(n)     {         case 1:         {             //some codes here          }         break;         case 2:         {             //some codes here           }         break;         case 3:         {          }         break;         case 4:         {             //some codes here `enter code here`         }         break;          default:         {             System.out.println(" I'm sorry you have chosen the wrong option...please enter again" );             {                 intro1();             }         }     }     exit(); }  public static void exit() {     Scanner obj=new Scanner (System.in);     System.out.println("to continue type 'cont' or else type 'exit'");     String pi=obj.nextLine();     if(pi=="exit")     {         System.exit(0);     }     else      {         intro1();     } } }   i'm facing the error please help me sort it out,as i have my project to be submitted....please...


Let $\sum a_n$ be a series of non-negative terms and let $$L = \lim_{n\to\infty}n\left(1-\frac{a_{n+1}}{a_n}\right)$$ Prove that the series converges (resp. diverges) if $L > 1$ (resp. $L<1$). I've tried, for example, that when $L<1$, $$n\left(1-\frac{a_{n+1}}{a_n}-L\right)= \frac{n(a_n-a_{n+1}-La_n)}{a_n}\ge\frac{n(a_n-a_{n+1}-a_n)}{a_n}=\frac{-na_{n+1}}{a_n}$$ and then using epsilons and the sort, but I can't get anywhere. Any tips?  P.S. using Kummer's test doesn't count


How can I back up and replicate a large MySQL database?

How can I backup a large database in mysql? And what is the best way to replicate the database?    what i'm looking for is backing up large database with large amount of data in a small time limit then restoring it within a small time of limit??


Radius of convergence for an unusual series?

I'm working through a pair of power series questions.  Find the radius of convergence for the following series: (1) $\sum_{n=0}^{\infty} 2^{n/2}x^n$ (2) $\sum_{n=0}^{\infty} 2^{n/2}x^{2^n}$ The unusual series is the second one.  It has the term $x^{2^n}$.  In particular its exponent is $2^n$ and I'm not sure how to proceed for figuring out its radius of convergence. How would you figure out the radius of convergence?  What would you use to do this?


Could we allow child Meta questions to be closed as duplicates of Meta.SE ones?

Now that we have one central cross-network Meta, we have a core place where network-wide issues can be discussed. There are a lot of great frequently asked questions and answers here, ones that will come up time and again on child Metas (like the new Meta.SO).  It would be great to be able to close these child Meta questions as duplicates of canonical entries here. This has come up a few times on Meta.SO already (such as for  on Meta.SO, which is a duplicate of  on Meta.SE), and we're ending up repeating ourselves by copying the answers from Meta.SE to answer the child Meta questions.  I know that there typically has not been an interest in allowing closing of cross-site duplicates as such, but this is a special case where I think there could be some benefit. It would both preserve one central repository of common canonical network-wide questions and answers and inform people of the presence of this site.   Otherwise, we'll be fragmenting the same questions across all of the child Metas, and in particular on Meta.SO we'll need to build up another set of canonical responses to the weekly "comments required for downvoting" and "why am I question banned" posts that we will certainly see so that we can close them properly.


Java - Return two dimensional array value

I want to return all values of 2D array. How I can return it if I use get method with String type?  public class Data { private final String[][] table; public Data(){     table = new String[][] {{"ID", "NAME"},                          {"101", "A"},                          {"102", "B"},                          {"103", "C"},                          {"104", "D"},                          {"105", "E"}}; }  public String[][] get(){     for (int i = 0; i < table.length; i++) {         for (int j = 0; j < table[i].length; j++) {             table[i][j] = table[i][j];         }     }     return table; }  public void displayMessage(){     System.out.println(get()); }   }


How do you show that $x^n+x+3$ is irreducible for all $n \ge 2$?


Is this proof for Theorem 16.4 Munkres Topology correct?

The followings is the Theorem $16.4$ from Munkres' Topology:    In the textbook it uses concept of subbasis to prove the theorem which I can't understand it. I tried to prove that in another way but I am not sure if I am correct.   Proof?:   1- Both $Y$ and $\emptyset$ are open in both typologies.   2- Basis elements in order topology in $Y$ are one of the three types: (1) All open intervals $(a,b)$ in $Y$; (2) All intervals of the form $[a_0,b)$, where $a_0$ is the smallest element (if any) of $Y$; (2) All intervals of the form $(a,b_0]$, where $b_0$ is the largest element (if any) of $Y$. Each of them can be written as $(c,d) \cap Y$ for $(c,d) \subset X$ an open set in $X$. And since $(c,d) \cap Y$ is open so the topology $Y$ inherited as a subspace of $X$ is finer than order topology in $Y$.   3- Any open set the topology $Y$ inherited as a subspace of $X$ is in the form $(c,d) \cap Y$ for $(c,d) \subset X$ an open set in $X$. This intersection is either $Y$ or $\emptyset$ or one the mentioned types of basis elements in order topology in $Y$ in paragraph 2. So the topology $Y$ inherited as a subspace of $X$ is coarser than order topology in $Y$. And we are done!   Is this proof a correct and rigorous one? And if not, is there any other simple proof not using subbasis?


Limit terminal command memory usage (previously CPU usage)

I have some binary I want to run in terminal, but if I run it, it quickly starts to use 100% of both CPUs, 100% of memory and the whole Linux freeze in a few seconds. Also I don't have source (in order to calm it down right from the inside). I googled a lot and found and tried two possible solutions:   nice - does literally nothing, the binary still uses 100% of both CPUs and 100% of memory quickly after I run it ulimit -v makes binary and even some other commands (like git) crash and throw some error   Is there any easy solution to limit CPU usage or memory by this binary and let it use e.g. only one CPU or 50% of both CPUs or only some small amount memory? I imagine something like this:  user@linux:~$ magical_command --limitmemory 1M --command mybinary    or:  user@linux:~$ magical_command --cpu both --limitcpu 50% --command mybinary   or:  user@linux:~$ magical_command --cpu one --limitcpu 100% --command mybinary     Update: From the comments below it looks like it is caused by memory rather than CPU overload, therefore I edited the question, but I still recommend @dbkeys' answer for those looking for CPU limiting magical command.  Update 2: As requested in the comments below: if I restart my notebook and only run terminal and that binary from terminal, nothing else, my notebook is significantly slowed down, mouse and keyboard works with delays or jerkily. But the binary is working for hours (most of time downloading and compiling dependencies), therefore I open Chrome and do some other stuff. If I open Chrome and let the binary run in the background, the whole linux freezes at all and nothing, even not mouse responds. I have to push a switch-off buton for 5 seconds to hard shutdown. But I can't just run it and go away, I want to work on some other stuff, therefore I want to limit somehow maybe both, that binary and Chrome.


When to use function expression and when to use function declaration

Here i have two questions regarding javascript functions   When to use function declaration and when to use function expression  This is an function expression   var run = function (){  // code stuff  }     This is an function declaration   function walk(){ // code stuff }   What do we call functions written inside below object(human) is it declaration or expression?   var human = {    think : function(){         }   roll : function(){       }   }