i have installed ubuntu on a partition and then i went to windows 7 and installed "easybcd" software to make grub as default loader and i also selected skip boot menu or something like that. From then on when i try to boot windows 7 from grub my system restarts and continues loading from grub. My windows boot loader menu is missing.  i have attached a picture which clearly shows i have windows 7 on a partition.Please help ![

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


I want to calculate a string in C# using either NCalc or DynamicExpresso library, the problem is, when the calculation gets complex and the numbers are big, it returns the wrong result. For example the code below returns -808182895 when it should return 3486784401  string value = "387420489*9"; value = new Interpreter().Eval(value).ToString();   Am i doing anything wrong? Thanks for the help.

If I have a string with a valid math expression such as:  String s = "1 + 2 * 7";   Is there a built in library/function in .NET that will parse and evaluate that expression for me and return the result? In this case 15.


my ubuntu is 17.04 and now I can't upgrade because of this error

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


If I'm looking for a tool or set of tools (software, mostly) to do something that I'm clearly not knowledgeable enough to create on my own, how can I get that without asking an off-topic shopping question on SE?  In other words, if I were to create my own tools, I could ask about all the details in multiple questions, and all of them would be perfectly legitimate.  But what if I want to just use a tool that someone else probably made already?  How do I find that?  I'm sure there are lots of people on the SE network that would know.  The only problem is that it's not allowed to ask here as far as I can tell.

I have a list of requirements for a program, but I don't know what program meets these criteria. That's about general-purpose software, for example, not a programming IDE or statistical workbench, questions about which would certainly go to respective sites.  Is this question appropriate on Stack Overflow? Where should I ask about it? On Super User or elsewhere?


Arrows show wrong axes. Something went wrong with the axes and they began to show absolutely wrong directions. Maybe someone know how to fix this?

For some reason the pivot point on my object has become rotated (other objects show normally oriented pivot points). I have to set the "transformation orientation" (see the bottom of my screenshot) to be able to see it though. Does anyone know how to change it back? That is, change it to be aligned with the "world orientation".


I know this may have been answered previously, but I'm trying to use the suggestions that were given to no effect. The solutions I tried are from this last post:  and here:   I'd welcome any advice. I even tried changing the paper orientation to landscape.  \begin{table}[] \centering \caption{My caption} \label{my-label} \begin{tabular}{|l|l|l|l|l|l|} \hline \textbf{Article Info} & \textbf{Study Size} & \textbf{RV EDV} & \textbf{RV ESV} & \textbf{LV EDV} & \textbf{LV ESV} \\ \hline ASO Guidelines: Cardiac Chamber Quantification. Citation: "Age-, Body Size-, and Sex-Specific Reference Values for Right Ventricular Volumes and Ejection Fraction by Three-Dimensional Echocardiography" & 540 & \begin{tabular}[c]{@{}l@{}}Men: 35-87 mL/m2\\ Women: 32-74 mL/m2\end{tabular} & \begin{tabular}[c]{@{}l@{}}Men: 10-44 mL/m2\\ Women: 8-36 mL/m2\end{tabular} & \begin{tabular}[c]{@{}l@{}}Men: 34-74 mL/m2\\ Women: 29-61 mL/m2\end{tabular} & \begin{tabular}[c]{@{}l@{}}Men: 11-31 mL/m2\\ Women: 8-24 mL/m2\end{tabular} \\ \hline Reference right ventricular systolic and diastolic function normalized to age, gender and body surface area from steady-state free precession cardiovascular magnetic resonance. Table 2 and 3. Stratified by age. & 120 & \begin{tabular}[c]{@{}l@{}}Men: a) 20-29 y/o: 91 b) 30 - 39 y/o: 88 c) 40 - 49 y/o: 85 d) 50 - 59 y/o : 82 e) 60 - 69 y/o: 79 f) 70 - 79 y/o: 75\\ \\ Women: a) 20-29 y/o: 84 b) 30 - 39 y/o: 80 c) 40 - 49 y/o: 76 d) 50 - 59 y/o : 72 e) 60 - 69 y/o: 68 f) 70 - 79 y/o: 64\end{tabular} & \begin{tabular}[c]{@{}l@{}}Men: a) 20-29 y/o: 35 b) 30 - 39 y/o: 33 c) 40 - 49 y/o: 30 d) 50 - 59 y/o : 28 e) 60 - 69 y/o: 25 f) 70 - 79 y/o: 23\\ \\ Women: a) 20-29 y/o: 32 b) 30 - 39 y/o: 30 c) 40 - 49 y/o: 27 d) 50 - 59 y/o : 24 e) 60 - 69 y/o: 21 f) 70 - 79 y/o: 19\end{tabular} & Not measured in this study & Not measured in this study \\ \hline Reference Values for Real Time Three-Dimensional Echocardiography–Derived Left Ventricular Volumes and Ejection Fraction: Review and Meta-Analysis of Currently Available Studies. Table 2 & 2806 & Not measured in this study & Not measured in this study & \begin{tabular}[c]{@{}l@{}}Men: 54.3 mL/m2\\ \\ Women: 49.0 mL/m2\end{tabular} & \begin{tabular}[c]{@{}l@{}}Men: 20.8 mL/m2\\ \\ Women: 17.3 mL/m2\end{tabular} \\ \hline \end{tabular} \end{table}   Thank you all in advance!

I have a table that I want to insert on a page, but at least one (perhaps both) of the following conditions are met:   The table is too wide to fit within the text block or page. That is, I'm exceeding some horizontal restriction. The table is too tall to fit within the text block or page. That is, I'm exceeding some vertical restriction.   What are my options to make this table fit? If it doesn't fit, regardless of my attempts, what other options exist?


We have to store lot of images with nested folder structure levels which is shared by many ASP.NET websites.What is the right approach? Should i Store content images in TFS or share folder? We also want to maintain multiple versions of the same image in future.

After having read  which I have followed a few questions come to mind that I am wondering if anyone can comment on.  I have a few components that make up a project I am working on. I have a smartclient, a webservice, a proxy for the webservice that the smartclient uses, a daemon and a common utilities library that is used in both the smartclient and the webservice. Each of the components are related to the same work project.  I have structured my source tree so that each of the components is independent - in other words each component (smartclient, webservice, daemon, proxy, common utilities) has its own trunk and its own solution file as I want to be able to release each component independently. For components that are used by other components, such as in the case of the smartclient using the proxy and the common utilities, I have created releases that are handled like any other 3rd party library (binaries referenced instead of projects). Can anyone confirm that this is somewhat a best-practice and if not how should this be done otherwise?  I have been building releases of my components using tfs build and am wondering where I should put the releases if anywhere other than in the build output directory where all the tfs builds reside. Should I perhaps check them (e.g. proxy release assemblies to be used by the smartclient) into TFS along with any other 3rd party libraries and then branch the release assemblies where they are to be used (e.g. branch proxy release dlls to the smartclient lib directory)?


I want to serve my website locally with my hostname. It's gibberish now, but people in my network can reach it. Let's say my hostname is  >hostname ABCabcABC   And, if my local people open a browser and open http://ABCabcABC, they can reach my website.   I want my website to be reached at, let's say, http://aaa  I tried changing my hostname with hostname command. It didn't work.   I tried to make a new VirtualHost file and typed a new 'ServerName` value, but it didn't work either.   How can I fix this?   Thanks in advance.

I have a Linux server (Ubuntu 12.04) I'm using to learn as much as I can about server management. I've got as far as getting a full LAMP setup running, but have hit a dead end trying to get a domain name to point to my server.  I've set up a virtual host in an Apache .conf file, and set up the IP address in the hosts file with the domain name, and have pointed the A record to the IP address with no luck. I've also installed bind9, but thought I'd see if I'm going in the wrong direction rather than messing anything up with that.  What is the best way to get a domain name up and running - ideally in a way that would be production ready rather than a temporary setup  EDIT: Thanks for the tips - just to better inform the situation - I have a few spare domain names registered that I can use, and I'm renting a VPS to play with. Currently I have the DNS * and @ A record pointing to the IP, but the nameservers are with the registrar if that makes a difference?


In , I read that the product of inertia $I_{xy}$ can be interpreted as the moment of inertia about the x-axis when the object rotates around the y-axis. I don't really understand this. Could somebody give me more details?

The tensor of moment of inertia contains six off-diagonal matrix elements, which vanish if we choose a reference frame aligned with the principal axes of the rotating rigid body; the angular momentum vector is then parallel to the angular velocity. But while considering the general case, what are the off-diagonal moment of inertia matrix elements? That is, do they have any physical significance as [say] the components of a vector? Or is it merely a mathematical construction with no definite physical meaning (which seems rather wrong to me)?  A similar thread exists  but they are more interested in the principal axes of the body. It also says:     The physical significance of the off-diagonal components is that   you're using a coordinate system not aligned with the principal   directions of the object. They tell us nothing interesting about the   object itself.   Is that all or is there more to it, perhaps related to properties of tensors in general?


Can quantum entanglement provide a faster way of transfer of information than the speed of light as it travells at a speed which is 10000 times faster than the speed of light

recently i was watching a  on quantum computing where the narrators describes that quantum entanglement information travels faster than light!  Is it really possible for anything to move faster than light? Or are the narrators just wrong?  Regards,


I've been reading through the questions about installing Ubuntu alongside Windows 10, but none seem to address this question. If I have a computer with a Windows 10 installation but no backup media, and I want to install Ubuntu alongside my original Windows 10 installation, how do I go about this? I do not want to brick my Windows 10 installation.   I have Windows 10 installed already but I observe that when I shutdown Windows 10 I have to be careful to actually shut it down - otherwise it will do a hibernate/sleep which has an associated hiberfile. This makes it impossible to mount the drive from an Ubuntu live disc.   Also, I have noticed that Windows 7 is finicky and will complain if I edit the disk using gparted to create additional partitions. (complain = unrecoverable boot error) I have to make partition changes in Windows itself.   What are the specific actions I should take in order to be able to have a functioning Ubuntu 16.04 installation and the original Windows 10 installation on the same computer? If I don't get answers to this question, my plan is to forge ahead with trying to do this and write up my path to success as an answer. It would be great if this has already been done and there is a writeup somewhere.

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


How do we solve this? I am stuck because of sqrt root to the power of 3  $$\lim_{x \to 0} \frac{(1+x)^{1/3}-1}{x}$$  Thsnk you for helping!

I currently have $$\lim_{h\to 0}\frac{\sqrt[3]{h+1}-1}{h}$$  Now, I know that when you have square root instead of a cubic root it's easy. You just multiply by the conjugate and simplify afterwards. If it were a sqrt I know that the limit is 1/2. I know that the result here is 1/3 but I can't seem to get there. I always end up with 1/4 due to getting something like: $$\frac{h+1-1}{h(\sqrt[3]{h+1}+1)(\sqrt[3]{h+1}+1)}$$  After simplifying and evaluating the limit you end up with $$\frac{1}{(\sqrt[3]{0+1}+1)(\sqrt[3]{0+1}+1)}$$  which turns out to be $1/4$.  What am I doing wrong?


Any advise on how I can delete all my photos in Google Photos?  I accidentally synced all the pictures from my iPhone, and now they consume all my 15gb capacity.  I highly appreciate any advise or workaround for this.

I've got 40GB of photos from my old Picasa Web Albums service and now I've just cancelled my storage plan.  Is there any way to remove all the photos and albums?  I searched a lot and I have no clue how to do it, I'm not going to delete near 400 albums individually, and obviously, not paying again for the storage plan.  I remember old days when google-cli was able to do this kind of stuff, but sadly it seems abandoned.


What is beyond the point of singularity in a black hole and universe expands in all the three $x$, $y$ and $z$ axis?  So how can one thing be on top of another when we don't know where the end point of the things is?  And how does a black hole connect two parallel universes?  And if there is another universe then is there another milky way, solar system and Earth?  And how does a black hole connect them?

I have four questions about black holes and universe formations.   Do new universes form on the other side of black holes? Was our own universe formed by this process? Was our big bang a black hole seen from the other side? Are there solid reasons why this might not be the case?


Q: Suppose $a$, $b$, $c$ and $d$ are real numbers, prove $[a,b] \sim (c,d]$. My thought: If the question was "prove $[a,b] \sim [c,d]$" then take the first interval on the x-axis and the second one on y-axis. Then we can define a function like $y=c+ \frac{d-c}{b-a}(x-a)$ that maps all the points in $[a, b]$ to $[c,d]$. However the interval in the question is different. I don't know how to apply the idea to this. Thank you.

I need to give an explicit bijection between $(0, 1]$ and $[0,1]$ and I'm wondering if my bijection/proof is correct. Using the hint that was given, I constructed the following function $f: (0, 1] \to [0,1]$: $$ x \mapsto \left\{ \begin{array}{ll} 2 - 2^{-i} - 2^{-i-1} - x & \text{if } x \in (1-2^{-i}, 1-2^{-i-1}]\text{ for an } i \in \mathbb{N}_0 \\ 1 & \text{if } x = 1 \end{array}\right. $$  It's easy to see that for every $x \in (0, 1)$, there exists such an $i$.  Now define $\tilde{f}: [0,1] \mapsto (0,1]$ with  $$ x \mapsto \left\{ \begin{array}{ll} 2 - 2^{-i} - 2^{-i-1} - x & \text{if } x \in [1-2^{-i}, 1-2^{-i-1})\text{ for an } i \in \mathbb{N}_0 \\ 1 & \text{if } x = 1 \end{array}\right. $$  I want to prove that $\tilde{f}(f(x)) = f(\tilde{f}(x)) =  x$, so it has an inverse and therefore is a bijection. The case $x=1$ is trivial, so assume that $x \in (0,1)$ with $x \in (1-2^{-i}, 1-2^{-i-1}]$ for some $i \in \mathbb{N}_0$. This interval has length $1-2^{-i-1} - (1-2^{-i}) = 2^{-i-1}$, so we can write $x = 1-2^{-i} + \epsilon\cdot 2^{-i-1}$ for some $\epsilon \in (0, 1]$. We now calculate $f(x)$: \begin{align*} f(x) &= 2 - 2^{-i} - 2^{-i-1} - x\\ &= 2 - 2^{-i} - 2^{-i-1} - (1-2^{-i} + \epsilon\cdot 2^{-i-1})\\ &= 1 - 2^{-i-1}(1+\epsilon). \end{align*} We conclude that $f(x) \in [1-2^{-i}, 1-2^{-i-1})$. We now use the definition of $\tilde{f}$, so if we calculate $\tilde{f}(f(x))$, we get \begin{align*} \tilde{f}(f(x))  &= 2 - 2^{-i} - 2^{-i-1} - f(x) \\ &= 2 - 2^{-i} - 2^{-i-1} - (2-2^{-i} - 2^{-i-1} - x) \\ &= x. \end{align*}  We conclude that $f$ has an inverse. Using exactly the same reasoning, we get that $f(\tilde{f}(x)) = x$ for all $x \in [0,1]$. Therefore it's inverse exists and it has to be a bijection.  I know there are less cumbersome methods of proving this fact, but as of now this is the only thing I can come up with.


I want to reduce the transaction log file size of my Database frequently.  If I use transactional log backup frequently for example every 1 hour will it reduce the database log size or not? Does transactional log backup affect database log file size?  Is shrinking the Database log file frequently a good idea or not?  Please guide which approach should I use.

This one seems to be a common question in most forums and all over the web, it is asked here in many formats that typically sound like this:  In SQL Server -  What are some reasons the transaction log grows so large? Why is my log file so big? What are some ways to prevent this problem from occurring? What do I do when I get myself on track with the underlying cause and want to put my transaction log file to a healthy size?


It appears that the iOS app still displays tags that are set to be ignored via the web interface.

I tend to use the Stack Exchange app over the weekends to do a bit of general browsing.  One of the sites is Board & Card Games, on which I've set it up, on the website, to hide magic-the-gathering tagged questions.  These still show on the iPad, and given the nature of the site tend to drown out most other questions.  The app already highlights questions tagged with a user's favorite tags.  Could we also have the app hide questions tagged with tags the user has marked for being ignored?


I want to capture the words after me_start: pattern with the following with regular expression me_start: ([\s\S]{1,})(?:end_1|end_2|end3) and till any of the described words in this OR list will be found. But it works in other way and capture the longest possible group.  Example:  me_start: cat end_1 dog end_2 in this sentence I want to capture cat word, but it catches cat end_1 dog words.  How to make it in the way I need

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


Wondering why the reference    \bibliographystyle{plain} \bibliography{Reference}   does not appear in my pdf when I compile it?  Any help appreciated.

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


\begin{tikzpicture}     \draw[black] (0,0) -- (3,0)     node[ pos=0.01,label=below:{-2}]{|}     node[ pos=0.16,label=above:{+}]{}     node[ pos=0.33,label=below:{0}]{o}     node[ pos=0.48,label=below:{-}]{}     node[ pos=0.66,label=below:{2}]{o}     node[ pos=0.81,label=above:{+}]{}     node[ pos=0.98,label=below:{3}]{|}    \end{tikzpicture}

My code is   \documentclass{standalone} \usepackage{pgf-umlcd}  \renewcommand{\unidirectionalAssociation}[4] {   draw[umlcd style, ->] (#1) -- (#4)   node[near end, auto]{#2}   node[near end, auto,swap]{#3}; }  \begin{document} \begin{tikzpicture}    \begin{abstractclass}[text width = 6cm]{FileStore}{0,0}     \attribute{$\sim$ com.alhelal.textpad}     \operation{+ orderFile(file : File) : EditableFile}      \operation[0]{\# createFile(file : File) : EditableFile}   \end{abstractclass}    \begin{class}[text width = 6cm,anchor = west,xshift = 5cm]{ProgrammFileFactory}{FileStore.east}     \inherit{FileStore}     \attribute{$\sim$ com.alhelal.textpad}     \operation{+ orderFile(file : File) : EditableFile}    \end{class}    \begin{class}[text width = 11cm, yshift = -2cm]{EditableFile}{ProgrammFileFactory.south}     \attribute{$\sim$ com.alhelal.textpad}     \attribute{+ languageBehavior : LanguageBehavior}      \operation{+ options : Options}      \operation{+ getCodeAreaFromTab(tb : Tab) : CodeArea}      \operation{+ saveFile(fileTabArrayList : ArrayList$<$FileTab$>$, option : Options)}     \operation{+ printFile(node : Node)}     \operation{+ toggleLineNumber(cd : CodeArea)}     \operation{+ setLanguageBehavior(langBehavior : LanguageBehavior)}     \operation{+ performRunCode(file : File)}     \operation{+ performBuildCode(file : File)}     \operation{+ performSetHighlightableText()}     \operation{+ performSetAutocompletableText()}   \end{class}    \begin{class}[text width = 3.5cm,anchor=north east,yshift = -2cm, xshift=-6cm]{TextFile}{EditableFile.south west}     \inherit{EditableFile}     \attribute{$\sim$ com.alhelal.textpad}   \end{class}    \begin{class}[text width = 3.5cm,anchor=north east,yshift = -2cm, xshift = -1.5cm]{CFile}{EditableFile.south west}     \inherit{EditableFile}     \attribute{$\sim$ com.alhelal.textpad}     \attribute{-path : String}   \end{class}    \begin{class}[text width=3.5cm,anchor=north west,yshift = -2cm,xshift=-3cm]{CplusFile}{EditableFile.south}     \inherit{EditableFile}     \attribute{$\sim$ com.alhelal.textpad}   \end{class}    \begin{class}[text width  = 3.5cm, anchor = north west, yshift = -2cm, xshift = -4cm]{JavaFile}{EditableFile.south east}     \inherit{EditableFile}     \attribute{$\sim$ com.alhelal.textpad}   \end{class}    \begin{class}[text width = 3.5cm,yshift = -2cm,xshift = 1cm]{PythonFile}{EditableFile.south east}     \inherit{EditableFile}     \attribute{$\sim$ com.alhelal.textpad}   \end{class}    \begin{class}[text width = 3.5cm, anchor = north west, yshift =-2cm,xshift = 5cm]{LaTeXFile}{EditableFile.south east}     \inherit{EditableFile}     \attribute{$\sim$ com.alhelal.textpad}   \end{class}   \unidirectionalAssociation{ProgrammFileFactory}{}{$<<$instantiate$>>$}{EditableFile}   \node [above=3mm] at (current bounding box.north) {Factory Method Pattern} \end{tikzpicture} \end{document}   I run this using pdflatex in terminal that results in


I try to run some commands at boot. I learned that one should add them in the /etc/rc.local file (on ubuntu 12.04 LTS).  Here my file:  #!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will "exit 0" on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing.  /usr/bin/touch /tmp/test.rc.local  exit 0   But after reboot no file was created in /tmp/ which indicates to me that rc.local was never executed.  Note: rc.local as (in my opinion) the right permission:  > ls -l rc.local  -rwxr-xr-x 1 root root 446 Sep  3 15:55 rc.local

I am PXE booting some Ubuntu machines in a cluster. All of a sudden my rc.local script has stopped working.  I've check the permission of /etc/rc.local:  -rwxr-xr-x 1 root root 1087 Jan 14 11:04 /etc/rc.local   I've checked that rc.local is symlinked in the following folders:  /etc/rc2.d  /etc/rc3.d /etc/rc4.d  /etc/rc5.d   They all symlink to /etc/init.d/rc.local.  I've tried to output echo lines from the script to /tmp/test.out but no luck. When I execute the rc.local script after the machines has booted, it works fine.  What can cause rc.local not to run?


I am trying to build my regex to validate phone numbers. These are the rules:   Telephones should not contain any characters except numbers and +  Other strings which doesn't start with 06 or +316 or 0316 or 00316 are invalid.   This is what I tried: $telephone = preg_replace('/[^0-9+]/','', $telephone);  removes all characters except + and numbers . Here still I need to check if the + is the first character or not. For example 466116+ or 21323+3122 are invalid.  preg_match('/^(06|+316)/i', $telephone) . I am trying here to add the starting conditions , but it doesn't work . Could you please help me out?  I am lost with regex :| Thank you

I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant.


According to Einstein's theory, nothing can travel faster then light and also a black hole doesn't allow light to escape but recently scientists got an image of a black hole. Here I am confused: if light can't escape from black hole as it lost most of its mass then how did scientists get the image of a black hole? If we can only see things which can reflect back light and if light can't be reflected back from the black hole then how do we get the image? Or is it just an illusion? Please guide me.

What exactly is the origin of the orange ring around M$87$?  I understand that the image was not taken in the visible light range. The colors are therefore artificial.   I also read that the image shows the shadow of the black hole on a brighter region of space which is "glowing" gas. Still I wonder about the following:   Why is the bright region circularly shaped and centered around the black hole? Is the bright region at the same distance as the black hole or much further away?


In May of 2015 my iPad Mini died because it got wet. I purchased a new iPad Mini 3 and reinstalled the apps I wanted on it ( and mourned the loss of my old Mini). Now that it's July and my new mini has its own backup I've discovered that I still have the backup to the old Mini (I know, I was pretty dumb that I didn't realize this sooner.)   Is there anyway to restore the old backup to the new iPad without losing the new backup? In other words, can I combine them?

I have an iPhone 6 (with proper iTunes backup) where all of my contacts where, but I bought a new iPhone 7 and had to initialize it as new iPhone, due to several time-related constraints, so now I have a few but new contacts on my new phone, but none of the older ones, but would be the best practice oriented, for just recovering the old contacts from the iTunes backups?  PS: I still have the old iPhone 6, so it could be used as "temporary storage" if needed.


Working with point data from Texas and am unfamiliar with what coordinate system it's using. Unfortunately, I am on a work computer which doesn't allow me to do much without admin privileges, so downloading and running Projectionuesser isn't a possibility at this moment.   Below is some examples of the point data:  2127838.753,    13709652.5  2061615.337,    13718121.64  2061615.337,    13718121.64  These points should all be in the San Antonio area of Texas.

I have a Shapefile but its coordinate system is Unknown, and there is no *.prj file.   How can I identify it now?


After I recently updated my computer software "Ubuntu" I went to my "System Settings" And click on "Software And Updates" There was something new I have never seen before.  Nvidia Corporation: G96 [GeForce 9500 GT] Below There are 5 Options.  1. "Using NVIDIA binary driver - version 340.76 from nvidia-340 (proprietary, tested)"  2. "Using NVIDIA legacy binary driver - version 304.125 from nvidia-304-updates (proprietary)"   3. "Using NVIDIA legacy binary driver - version 304.125 from nvidia-304 (proprietary)"  4. "Using X.Org X server - Nouveau disaplay driver from xsever-xorg-video-nouveau (open source)"  5. "Using NVIDIA binary driver - version 340.76  from nvidia-340-updates (proprietary)   I really don't know what these mean so if you do please tell me withc one to choose.   Theres one more also, below the options,   Unknown: Unknown This device is not working.  1. "Using Processor microcode firmware for AMD CPU's from amd64-microcode (proprietary)   2. Do not use this device  So I have no clue on what these are if you have any info or idea on witch one i should use, Please Tell me Thanks!  System Info  Processor AMD Phenom(tm) II X6 1090T Processor × 6  Graphics GeForce 9500 GT/PCIe/SSE2  OS type 64-bit  Disk 968.0 GB  Ubuntu 15.04

Is there a package of Ubuntu drivers as driver pack solution? I tried to search for it, but I did not find it. If there is, how can I easily get it?


Here is the code: File tempFile = new File("myTempFile.txt"); tempFile.createNewFile(); File inputFile = new File("Friend_list.txt");  BufferedReader reader = new BufferedReader(new FileReader(inputFile));     String currentLine;  while((currentLine = reader.readLine()) != null) {     String trimmedLine;     trimmedLine = currentLine.trim(); }             In this part of the code, there is a NullPointerException. The exact exception is mentioned below: Exception in thread "main" java.lang.NullPointerException: Cannot invoke  "String.trim()" because "currentLine" is null at com.company.Main.delete(Main.java:167) at com.company.Main.main(Main.java:48)  The question is if the string is null then how could it enter the while loop? I cross checked the file, data is there in the file then how could it be null?

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I have noticed that some native English speakers do not pronounce the "T" in "won't" in the middle of a sentence.  For example:     I won't make you happy   sounds like:     I wo make you happy   Is this correct ?

Well, I usually say "twenny" instead of "twenty" (not "twendy" even). I recently noticed that I never heard the same from any native english speakers during any talks I ever had with them.  Recently I had a brief search on the 'net and it seems that it is somehow okay to say "twenny", but it might look the least correct pronunciation for most of the people, or they might think you have strange accent, etc.  So, my question is, is there any good reference which clearly proves saying "twenny" instead of "twenty" is totally correct or wrong?  P.S. You're most welcome to write your very personal opinion if you don't know any good references.  Update  I've already looked at the major dictionaries and didn't find any of them lists "twenny" in their pronunciation's section, however I'm sure that I didn't made that up, but I heard that while ago. Maybe in a movie, maybe from someone, and that's why I'm looking for the answer.


Harmonic series diverges and pseudo Cauchy however it's not bounded. So how can I find such a sequence?  A sequence $(s_n)$ is pseudo-Cauchy if, for all $\xi>0$, there exists an $N$ such that if $n ≥ N$, then $|s_{n+1}−s_n| < ξ$.

If I have a sequence {$a_n$} that has the property of $\lim(a_{n+1}-a_n)=0$, does that make it a Cauchy Sequence. I think it doesn't because $a_n = \sum_{k=1}^n \frac{1}{k}$ is a counter example.   However, by definition, there exists a $M$ such that if $n \geq M$ then $|a_{n+1}-a_n| < \frac{\epsilon}{m-n}$  Hence, we have $|a_m - a_{m-1}|+.....+|a_{n+1}-a_n|<|a_m -a_n| <\epsilon$  This proof doesn't work because I cannot be sure I can find a fixed $M$ which might change according to n.  But I wonder if I have an additional condition that says $a_n$ is bounded, I think then the proof works and that I should be able to find a fixed $M$. However, I don't know how to justify this. Maybe I am wrong. Can someone kindly help me figure out this problem. Thanks


I'm having problem trying to fit a long text inside a box. I can't change the size of the box due to client's design specification so I have to get the text to fit the box instead. It can be achieved with html css js or jquery it doesn't matter as long as I get to the desired effect.

     MyNameIs30CharactersLong

     MyNameIsShort

   Here's a screenshot of what I'm trying to achieve:    Here's how it is with a long name:    Thank you for your help!

I need to display user entered text into a fixed size div.  What i want is for the font size to be automatically adjusted so that the text fills the box as much as possible.  So - If the div is 400px x 300px.  If someone enters ABC then it's really big font.  If they enter a paragraph, then it would be a tiny font.  I'd probably want to start with a maximum font size - maybe 32px, and while the text is too big to fit the container, shrink the font size until it fits.


I wonder, what's the difference between I'm finished and I finished (or even I've finished)?  To be more specific:  I'm given = someone gives something to me  I'm told = someone tells something to me  I'm finished = NOT someone makes me finish BUT  I have finished doing something.  Why?

I was trying to say the following and got bewildered with the different choices.     I have "To Kill a Mockingbird" on my list. I will write you about it when I am finished reading it.      I have "To Kill a Mockingbird" on my list. I will write you about it when I have finished reading it.      I have "To Kill a Mockingbird" on my list. I will write you about it when I am done reading it.      I have "To Kill a Mockingbird" on my list. I will write you about it when I finish reading it.   I am not sure which one to pick. I am confused with the exact meanings of these various choices. Could someone also shed some light on what meanings the different tenses convey in a context like this.


I was setting up some ignored tags today, and I noticed that after adding an ignored tag through the sidebar UI, the Ignored Tags section disappears after you refresh the page, and won't show up again until you click the "edit" button to edit your favorite/ignored tags again (see screenshots).  Before (after adding ignored tag)    After page refresh    I've reproduced the behaviour in both:   Chrome 45.0.2454.101 m Opera 31.0   so I assume that this isn't specific to a particular browser. I've also reproduced the behaviour here on MSE, as well as Stack Overflow, so I assume that it's not specific to a particular exchange site either.  So is this a bug, or is this the intended behaviour? If intended, what's the rationale behind it?

On Stack Overflow, I got bunch of favorite tags and couple of ignored tags. Both groups used to show in the front page, until today:        When editing the favorite tags they do appear though so not all is lost:        Can I see my ignored tags without having to edit?


What is today's date vs What date is it today ?  Is there an alternative to this?

Which of the following is grammatical?        What date/day is it today?     What date/day is today?


Can anyone help me to find out that how can we increase website speed to resolve Add expires headers for google maps and Analytics. Please see below images. There are 9 component without expire header tags.

I am trying to decrease the loading time of my website which is hosted in . So when I check the performance scores via  under YSlow section it mention to "Add expire headers" for four static components as below.        Add Expires headers   There are 4 static components without a far-future expiration date.      https://www.googletagmanager.com/gtag/js?id=UA-49812165-2     https://www.google-analytics.com/analytics.js     https://www.trustedsite.com/rpc/ajax?do=tmjs-visit&host=surf2ship.com&rand=1565102041274     https://cdn.ywxi.net/meter/surf2ship.com/105.png   So to have a better answer for this I have google the issue and below links were studied       All of above pages explain how to add expire headers for common file types. For a example see below .htaccess file. It specify all common formats rather than specifying a exact source.   # Media: images, video, audio   ExpiresByType audio/ogg "access plus 1 month"   ExpiresByType image/gif "access plus 1 month"   ExpiresByType image/jpeg "access plus 1 month"    How to add Expire headers for a specific url? Like for https://www.google-analytics.com/analytics.js  This is my current scores for the site


I have a project where I need to add a custom marker when the user clicks on the map. I have created my own SVG in order to show this custom marker. The problem I am facing is that the marker doesn't show correctly where the mouse has clicked. The marker is positioned with the left top border on the mouse position. But I need the bottom of the pin to be positioned where the mouse has clicked.  var svg = `<svg width="19px" height="29px" viewBox="0 0 19 29" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">     <title>Combined Shape</title>     <desc>Created with Sketch.</desc>     <g id="Onboarding" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">         <g id="2.6-Charging-rate" transform="translate(-728.000000, -436.000000)" fill="#FFFFFF">             <g id="Group-14" transform="translate(728.000000, 436.000000)">                 <path d="M9.5,0 C14.7467051,0 19,4.32791409 19,9.66666667 C19,15.0054192 11.4233864,29 9.5,29 C7.57661364,29 0,15.0054192 0,9.66666667 C0,4.32791409 4.25329488,0 9.5,0 Z M9.5,5 C7.01471863,5 5,7.01471863 5,9.5 C5,11.9852814 7.01471863,14 9.5,14 C11.9852814,14 14,11.9852814 14,9.5 C14,7.01471863 11.9852814,5 9.5,5 Z" id="Combined-Shape"></path>             </g>         </g>     </g> </svg>`;  var iconUrl = 'data:image/svg+xml;base64,' + btoa(svg); var icon = L.icon({   iconUrl: iconUrl }); this.marker = new L.Marker([e.latlng.lat, e.latlng.lng], {   icon: icon }).addTo(this.map);

I am using a customer marker to represent metro stops in my leaflet map. The problem is that the markers are changing their position every time I zoom in or out. When I finally zoom in to the last level they reach their specified position. How can I make them stay at the same place at all times like the default leaflet markers? The icon anchor option isn't working for me. Which option or property am I missing?


I am in minecraft 1.8.9, and when I try to do /gamerule KeepInventory true, it says the command has been updated, and then I go and do /kill. But I still lose my items, both in creative and in survival. What am I doing wrong?  @Arperum mentioned in the comments that it should be keepInventory, but on some worlds, when I type /gamerule and cycle through the rules, the one with the uppercase "K" shows up. Is that a glitch?

I once played a vanilla Minecraft adventure map (called "Herobrine's Mansion") that prevented the player from losing their items on death. Which commands can be used to prevent the player from losing their items on death (in vanilla Minecraft)?


I am trying to iterate through a simple php array, and have run into bizarre behavior that is causing iteration to terminate early. My php version is 5.6.3.  The following code prints the numbers 1 through 5, as expected...  $values = array(1, 2, 3, 4, 5);      foreach ($values as $v)         //$temp_variable = $v;         echo "v: " . "$v" . "\n";     However, if I uncomment the line with the temporary variable, like so, we only get one iteration!  $values = array(1, 2, 3, 4, 5);      foreach ($values as $v)         $temp_variable = $v;         echo "v: " . "$v" . "\n";     This seems extremely bizarre. How could the act of creating an unused temporary variable cause our loop to go off-the-rails? Any advice would be appreciated, thank you!

Why does everyone tell me writing code like this is a bad practice?  if (foo)     Bar();  //or  for(int i = 0 i < count; i++)     Bar(i);   My biggest argument for omitting the curly braces is that it can sometimes be twice as many lines with them. For example, here is some code to paint a glow effect for a label in C#.  using (Brush br = new SolidBrush(Color.FromArgb(15, GlowColor))) {     for (int x = 0; x <= GlowAmount; x++)     {         for (int y = 0; y <= GlowAmount; y++)         {             g.DrawString(Text, this.Font, br, new Point(IconOffset + x, y));         }      }  }  //versus using (Brush br = new SolidBrush(Color.FromArgb(15, GlowColor)))     for (int x = 0; x <= GlowAmount; x++)         for (int y = 0; y <= GlowAmount; y++)             g.DrawString(Text, this.Font, br, new Point(IconOffset + x, y));   You can also get the added benefit of chaining usings together without having to indent a million times.  using (Graphics g = Graphics.FromImage(bmp)) {     using (Brush brush = new SolidBrush(backgroundColor))     {         using (Pen pen = new Pen(Color.FromArgb(penColor)))         {             //do lots of work         }     }  } //versus using (Graphics g = Graphics.FromImage(bmp)) using (Brush brush = new SolidBrush(backgroundColor)) using (Pen pen = new Pen(Color.FromArgb(penColor))) {     //do lots of work }     The most common argument for curly braces revolves around maintance programming, and the problems that would ensue by inserting code between the original if statement and its intended result:  if (foo)     Bar();     Biz();     Questions:   Is it wrong to want to use the more compact syntax which the language offers? The people that design these languages are smart, I can't imagine they would put a feature which is always bad to use. Should we or Shouldn't we write code so the lowest common denominator can understand and have no problems working with it?  Is there another argument that I'm missing?


Declaration: Ive searched high and low on SOF for an answer but I doesnt click with my problem. attempting to create a condition that if the last two elements of an input argument = 'sh' or 'ch', append 'es' to the end. elif word [-2:-1].lower() == 's' + 'h' or (word [-2:-1].lower() == 'c' + 'h'):            word = word + 'es'      dictionary ['plural'] = word; dictionary ['status'] = 'success'  #dictionary format  the output im getting at the moment : pouch --> {'plural': 'pouchs', 'status': 'success'}  This is taking place (i think) since I have a prior condition that any input argument that does not come from my file (containing a list of strings) should be pluralized with the letter 's'. This would be my last condition in my program: elif word not in proper_nouns:                                   word = word + 's'      dictionary ['plural'] = word; dictionary ['status'] = 'success'

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


I want to know how to calculate the value of sin, not using table values or calculator.  I found this $\frac{(e^{ix})^2-1}{2ie^{ix}}$, but how to deal with $i$ number, if it's $\sqrt{-1}$?

In school, we just started learning about trigonometry, and I was wondering: is there a way to find the sine, cosine, tangent, cosecant, secant, and cotangent of a single angle without using a calculator?  Sometimes I don't feel right when I can't do things out myself and let a machine do it when I can't.  Or, if you could redirect me to a place that explains how to do it, please do so.  My dad said there isn't, but I just had to make sure.  Thanks.


So basically i am a beginner 3D modeler, i tried to 3d camera track a video but i keep getting solve errors, my tracking points are not dancing it is still as a rock, Please help me, i already tried to

Whenever I do camera tracking in Blender the reconstruction is always zooming out or not on the axis. I have a great quality camera, but the end results of the camera tracking always has the model sliding. If you have a solution please tell me.


Before the first time I use a none-stick teflon pan, how should I do seasoning?  1- Should I first rub oil on it then heat it? [ref1] or first I should heat it then remove heat and rub oil on it? [ref2],[ref3]  2- How long should I heat it for 30 seconds (ref3)?  an hour (ref4)!!! or 2-3 minutes (ref5)?  3- How much hot should oil be? Smoking point or light flame?  4- After seasoning what to do? should I wash the oil off? or leave it on the pan for a while?  5- Should I use cooking oil or frying oil (I think they write cooking oil but they mean frying oil)?  6- After each time using pan, should I wash it immediately or letting oil solidify on pan then after I ate my food I wash it?  7- To extend life span, should I rub some oil on pan after each time washing?  I appologize for links. Since I do not have 10 reputation, I cannot have more than 2 links.  ref1: www.thekitchn.com/surprising-tip-do-you-season-your-nonstick-pans-187938  ref2: en.wikipedia.org/wiki/Seasoning_%28cookware%29  ref3: www.ehow.com/how_7745528_season-non-stick-cookware.html  ref4: cooking.stackexchange.com/questions/34420/wok-patina-comes-off/41164  ref5: www.productknowledge.com/more-myths-nonstick-coatings-myth-13.html

I am not sure if I am allowed to say the brand & model, but here is the spec   Can also be used in the oven since it is made entirely of metal. Thick base with one layer of aluminium between two layers of stainless steel. Gives an even and energy-efficient heat, which reduces the risk of food burning and sticking. Made of stainless steel, which makes the pan durable and easy to clean. Treated with Teflon® Platinum plus, a very hardwearing non-stick coating that makes the pan suitable for everyday use. The exterior is made of brushed steel which means that stains do not show as much as on a high-gloss surface.   Should I season it?  Related question:


In a past narrative, I often see people using Past Perfect Progressive for things that are still true, which is odd to me, as the Past Perfect Progressive is an action that started in the past and continued up until a point in the past. For instance  He asked calmly, scuffing his shoes on the carpet that hadn't been vacuumed for a long time  Shouldn't it be:  [...] wasn't been vacuumed for a long time  Since the Past P. is supposedly for things that stopped being true after some point in the past?

Is it more natural to speak in simple past or past perfect when explaining past events to a friend? It seems like Americans use more simple past in everyday life than past perfect. I found this example online:     I had almost completed my essay when my computer suddenly crashed and I noticed that I had forgotten to save the document.   Is it wrong to say the following instead?     I was almost done with my essay when my computer suddenly crashed and I noticed that I forgot to save the document.   Maybe it's just my friends, but I rarely hear them speak in past perfect, so I'm really torn about using past perfect when it isn't necessary.


I want to subtract from the output of the nproc command and run another command using the calculated value.  The following doesn't work in linux:  somecommand --set_cpus = (nproc - 1)

So I have a script that, when I give it two addresses, will search two HTML links:  echo "http://maps.google.be/maps?saddr\=$1\&daddr\=$2" | sed 's/ /%/g'   I want to send this to wget and then save the output in a file called temp.html. I tried this, but it doesn't work. Can someone explain why and/or give me a solution please?  #!/bin/bash url = echo "http://maps.google.be/maps?saddr\=$1\&daddr\=$2" |  sed 's/ /%/g' wget $url


I know this sounds really weird, but I don't want access to my Stack Exchange account for a while, but I would like to keep it to use in the future. Is it possible for the SE team to freeze my account?  It is like this: I like SE. I am beginning to feel I like it a bit too much. In order to make sure that participating on SE does not have a negative impact on other priorities, I have decided to put my activity on hold. This brings me to a position in which it is a choice between having my account frozen somehow, or deleting it. I really don't want to delete my account, as I have just made it over 2k rep; I would lose all of my rep, badges and privileges, and have to start all over again from scratch.  That brings me back to the question: Is there any way possible to have my account locked or frozen?

Is it possible to obtain a suspension on one's own user account by request?  If so, will the message on my profile make it clear that the suspension was requested, or will it look like I got in trouble?


I have numpy arrays as follows.  x = array([0.1]) y = array([0.2]) z= array([-0.05])   I want to get the value of them as a number. Therefore, I did the follwoing.  print(x.tolist()[0]) print(y.tolist()[0]) print(z.tolist()[0])   However, it gave me the following results which is incorrect.  0.09999999999999996 0.19999999999999998 -0.049999999999999975   I am wondering if there is a way to get 0.1, 0.2, -0.05 respectively.  I am happy to provide more details if needed.

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I'm trying to use a multi valued string in a Store Procedure, but the IN operator is only accepting the values in Hard Coded mode.  Like, if I write the values directly in the Code it works, but if the value is retrieved from the SELECT command, it return nothing...   Anyone can help on this?  For testing:  DECLARE @AUX nvarchar(255);  SET @AUX = (SELECT GROUP FROM FRUITS WHERE FRUIT = 'APPLES');  PRINT @AUX;  SELECT *  FROM FRUITS  WHERE FRUIT IN (@AUX);   This returns nothing. But the value inside @AUX is retrieved, and contains something like 'Red','Green','Starkling' .  If I use that Select command only it works.  And if I hard core inside the IN the Values it works also.  SELECT *  FROM FRUITS  WHERE FRUIT IN ('Red', 'Green', 'Starkling');   This works.  I tried to output the value inside the variable @AUX and is correct... So why the IN doesn't read the values?  TIA

How do I parameterize a query containing an IN clause with a variable number of arguments, like this one?  SELECT * FROM Tags  WHERE Name IN ('ruby','rails','scruffy','rubyonrails') ORDER BY Count DESC   In this query, the number of arguments could be anywhere from 1 to 5.  I would prefer not to use a dedicated stored procedure for this (or XML), but if there is some elegant way specific to , I am open to that.


Given 3 balls, there are 3 ways to partition them into bins:  (3) (2,1) (1,1,1)   Note that (1,2) is already covered in (2,1), since we don't care about the order of the bins.  I'd like to write a function that gets the number of balls n and outputs all  possible partitions, in an efficient way.  This is what I came up with:  from itertools import combinations from functools import reduce def all_partitions(n):     n_bits_on=set([tuple(reduce(lambda x,y:x[:y]+[1]+x[y+1:],c,[0]*(2*n-1))) for c in combinations(range(2*n-1),n)])     return set([tuple(sorted(filter(lambda i:i>0,reduce(lambda x,y: x+[y] if y==0 else x[:-1]+[x[-1]+1,],p,[0])))) for p in n_bits_on])   What the code does is:   Generate all bit-arrays of size 2n-1 and n bits on (using itertools.combinations) Regard zeros as partitions and ones as balls - sum the number of ones between two zeros (with reduce) Sorting all options, and removing duplicates with set()   The code works, but it is very slow.  Any ideas how can it be improved ?

I needed an algorithm to generate all possible partitions of a positive number, and I came up with one (posted as an answer), but it's exponential time.  The algorithm should return all the possible ways a number can be expressed as the sum of positive numbers less than or equal to itself. So for example for the number 5, the result would be:   5 4+1 3+2 3+1+1 2+2+1 2+1+1+1 1+1+1+1+1   So my question is: is there a more efficient algorithm for this?  EDIT: Question was titled "Sum decomposition of a number", since I didn't really know what this was called.  that they were called "partitions," so I edited the question title accordingly.


I played Star Trek Catan for the first time last night and really enjoyed what the command cards (Sulu, Kirk, Spock) added to the game.  I would like to purchase a deck of command cards themed to match regular Settlers of Catan. Does this exist in one of the expansions, or as a standalone?  Edit: Sorry, this is a duplicate of

I see that "Star Trek" catan has some extra role cards, which add a new element to the game (and are the only things that do).  I'd like to try these, but I don't really like the "Star Trek" theme, and it's expensive.  Has anyone made some printable versions of these cards that fit the original Catan theme?


I'm a self-learning graphic designer. I work with Photoshop, Illustrator and InDesign and I thought I was doing fine until I got this big shock at work. I've been working for a year at some web design company and just now they tell me I'm inexperienced and that I failed with the task that I've been assigned to me.  Now from my perspective, I want to know how to sharpen my talent. I know I have the talent, but I think I maybe missed some basic concepts and principles which I would have studied had I attended the a graphic design school. I want to spot my weaknesses and I desperately need a good mentor who is willing to help me find them and guide me in fixing them.

I'm currently a student at an art school, however I know I lack a large amount of experience to even be considered a graphic designer. I don't think I have the portfolio/experience yet to do internships. I do personal projects of my own, research, and read as much as I can about the industry.   But I want to learn as much as I can and gain as much knowledge/advice from experienced graphic designers. But I want to be as respectful and professional as I can about this, so I don't waste the person's time. So I was wondering where I could begin to look and how I could even go about this. I wouldn't mind simple email correspondence with the individual, but I wasn't sure if that was deemed professional. Thank you!


It has pretty much been answered here,   but I don't really understand how it was done. Also, is there another, simpler way to show this than the way in the question above?

I'm an intro analysis student trying to prove that any field $f$ that contains the integers contains the rationals as a subfield. I'm asked to proceed by proving  that there exists a subset $F'$ of $F$ and a function $Φ: F'→\mathbb{Q}$ such that $\mathbb{Z} ⊂ \mathbb{Q}$ and $Φ$  satisfies the three following properties:    $Φ $ is bijective  $Φ(a + b) = Φ(a) + Φ(b)$, for $a$, $b$ ∈ $F$ $Φ(a.b) = Φ(a).Φ(b)$, for $a$, $b ∈ F$   I have gone through a few answers for similar questions but I am not sure how to proceed. We have not covered isomorphisms in the course yet so I am unsure how this is related to it (though other posts like  and  indicate that there's a connection). Any help would be greatly appreciated.


I heard this problem from my friend today, but unfortunately we could not figure out what's happening here.  $$x^{x^{\large x^{x^{\unicode{x22F0}}}}}=2$$ $$x^2=2$$ $$x=\sqrt2$$  but  $$x^{x^{\large  x^{x^{\unicode{x22F0}}}}}=4$$ $$x^4=4$$ $$x=\sqrt2$$  I have a feeling that this might be a duplicate, but I could not find this problem (basically I couldn't figure out what to search). So what's happening here, and what's the real value of $$\sqrt2^{\sqrt2^{\large  \sqrt2^{\sqrt2^{\unicode{x22F0}}}}}$$  ?

Find $x$ in   $$ \Large 2 = x^{x^{x^{\:\cdot^{\:\cdot^{\:\cdot}}}}}$$   A trick to solve this is to see that $$\large 2 = x^{x^{x^{\:\cdot^{\:\cdot^{\:\cdot}}}}} \quad\implies\quad 2 = x^{\Big(x^{x^{x^{\:\cdot^{\:\cdot^{\:\cdot}}}}}\Big)} = x^2 \quad\implies\quad x = \pm \sqrt{2} $$  Are these solutions correct? If not, why? If yes, are there other solutions?    PS: An extension of this discussion can be found in


I'm doing a calculator, in which is asked to the user to put two numbers, and then an aritmethical operator, so a set of IFs will understand what operator it is and do the operation required: public class Calc {    public static void main(String args[]) { Scanner input = new Scanner(System.in);   System.out.print("First number: "); double num1 = input.nextDouble();  System.out.print("Second number: "); double num2 = input.nextDouble();  System.out.print("Artithemtical operator(-, +, :, x): "); String segn = input.nextLine();   if(segn == "+" ) { System.out.println(num1 + " + " + num2 + " = " + (num1 + num2)); } else if(segn == "-") { System.out.println(num1 + " - " + num2 + " = " + (num1 - num2)); } else if(segn == "x") { System.out.println(num1 + " x " + num2 + " = " + (num1 * num2)); } else if(segn == ":") {    System.out.println(num1 + " : " + num2 + " = " + (num1 / num2)); }      } }  as you can see if the input is a specific operator it will perform the specific task. It works well, it makes you put the two numbers, the operator but then it does nothing, what shall I do?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


How do I get the start command from an existing launcher entry on 16.04?

I want to use some applications shown on the Unity Launcher in a terminal, but I need to know the appropriate command to run them. How can I achieve that?


Euclid's lemma: Let $A$ be a principal ring with $x$ and $y$ belonging to $A$, and $p$ an irreducible element of $A$. If $p$ divides the product $xy$, then $p$ divides $x$ or $p$ divides $y$. Definition of irreducible element: A non zero element p is said to be irreducible in A (where A is an integral domain) if p is non invertible in A and all divisors of p in A are trivial. In other words a nonzero element p of A is irreducible iff p is non invertible and the only divisors of p in A are the invertible elements of A and the elements associated to p. Question: Should $A$ be an integral domain too? And I need a justification why please. I'm not quite grasping why an integral domain can help with such lemmas.

Could anyone explain to me why maximal ideals are prime?  I'm approaching it like this, let $R$ be a commutative ring with $1$ and let $A$ be a maximal ideal. Let $a,b\in R:ab\in A$.  I'm trying to construct an ideal $B$ such that $A\subset B \neq A$ As this would be a contradiction. An alternative idea I had was to prove that $R/A$ is an integral domain, but this reduces to the same problem.  EDIT: Ergh.. just realized that I've learnt a theorem that states is $A$ is a maximal ideal then $R/A$ is a field


Until 19.04 i had a link to my secondary drive located on the desktop, now there seems to be no way to save such a link.

I upgraded to Ubuntu 19.04 from 17.10 and now I do not have anything on my desktop at all. I am running this on Virtual Box 6. I know enough about Unix to be dangerous, I just use it for developing websites.    From looking around various articles I have tried these commands as suggested but nothing has worked, any ideas?  From SSH I have tried these:  sudo apt-get install --reinstall ubuntu-desktop sudo apt install --reinstall gnome-shell-extension-desktop-icons sudo apt install --reinstall gnome


Is there a way to convert  to Lat/Long in Javascript?  I have seen another thread on this but it was in Java and Python which won't help me much.  Please let me know, thanks.

I have a bunch of files with coordinates in UTM form. For each coordinate I have easting, northing and zone. I need to convert this to LatLng for use with Google Map API to show the information in a map.  I have found some online calculators that does this, but no actual code or libraries.  is a projection library for Javascript, but looking at the demo it doesn't include UTM projection.  I am still pretty fresh to the entire GIS domain, so what I want is something ala:  (lat,lng) = transform(easting, northing, zone)


This was something I found when testing a bit of low-quality content against the system.  This error:  Appeared when I clicked the "Post question" button (not the review), but the page scrolled back up to show this:  Instead of scrolling down a touch to show you the error.  I imagine this would be a little confusing for new users, and was confusing to me too. Steps to reproduce:  Enter This is a test title to test something in the title and body. Enter  as the tag. Click "Review" and then "Post question".  Can we fix this please, and don't show the "Question ready to publish" notice when the quality error comes up.

Don't say "Your question is ready to publish!" if "This post does not meet our quality standards".   Steps to reproduce this:  Go to  (note: the issue is not specific to this Stack Exchange website) Add "Is the expression “very worth” proper English, and if not, what are some alternatives?" in the title and body Add "gmail" as tag Click on "review your question" Click on "post your question"  To be clear, I'm not asking for specific feedback on the question above. It is just an example that I used to demonstrate the issue I'm concerned about, which is that the "Your question is ready to publish!" message is displaying for questions that don't meet the site's quality standards. Instead of that message, the user should be told that the question isn't ready to publish because it doesn't meet quality standards.


We publish an app which is a managed package and contains an article type object in Classic Knowledge. With Lightning Knowledge coming in picture, Lightning knowledge customer upgrades are failing due to an article type existing in our package. What are options for us to immediately avoid this situation as our customers are blocked from upgrades?  Edit: I came across this idea submitted on Salesforce board:, anyone knows of an existing workaround for this?

We manage a Salesforce app via a managed package which includes a Classic knowledge article type object lets say 'Comm_Article__kav' . Now that our customers are using Salesforce orgs with Lightning knowledge enabled in their environments, our app installation fails in them on the ground of  Article types are not allowed in Lightning knowledge enabled orgs. So how can we handle this situation. Snippet of error message while installing the package:      (Comm_Article__kav) When Lightning Knowledge is enabled, you can’t add   an article type. Comm_Article__kav: When Lightning Knowledge is   enabled, you can’t add an article type.   Possible solutions I thought of:    Alter package to support Lightning Knowledge and Classic Knowledge both as few of our customers still use classic knowledge Build our package to use dynamic references exclusively, and  dynamically determine whether org is operating in Lightning or Classic  Knowledge.   Are these feasible ? If yes, how?


$0 = 0 + 0 + 0 + ...$   $0 = (1 - 1) + (1 - 1) + (1 - 1) + ...$   $0 = 1 - 1 + 1 - 1 + 1 - 1 + ...$   $0 = 1 + (-1 + 1) + (-1 + 1) + (-1 + ...$   $0 = 1 + 0 + 0 + 0 + ...$   $0 = 1$   I can't really tell what is obviously wrong with this. It seems to use the same logic as we see in the derivation of things like $\sum_{k=1}^{\infty} k = -\frac{1}{12}$ which appears to be a quirky but accepted fact in mathematics.

Today, a friend gave me a "proof" of $1=2$ and challenged me to find the fallacy.     $1 = 1$      $1 = 1 + 0 + 0 + 0 ...$      $1 = 1 + 1 - 1 + 1 - 1 + 1 - 1 ...$      $1 = 2 - 1 + 1 - 1 + 1 - 1 ...$      $1 = 2 + 0 + 0 ...$      $1 = 2$   My answer was that once you turn the initial $1 + 1$ into a 2, everything is offset so a $-1$ is always left at the end no matter how many times it is repeated. This negative one balances out the $2$ at the beginning so $1=1$ still holds true. I.e.  $$1 = 1 + 0 + 0 + 0 ... = 1 + (1 - 1) + (1 - 1) + (1 - 1) = 2 + (-1 + 1) + (-1 + 1) - 1$$  However, my friend claimed that my answer only applies if the $+ 1 - 1$ repeats for a finite number of times. He argues that because the sequence repeats infinitely and things work differently when working with infinity, my answer is not valid.  Can anyone enlighten me to the true fallacy in this proof?


I flagged  as "Not an answer" but my flag was declined:    I want to improve my flags by understanding what posts should I flag and what kind of flag should I arise, so I entered the question to see it again. I saw that it was deleted by a moderator and it's totally not an answer.   What could be the reason for declining my flag? That's not the first time my flag was declined but the post was deleted by a moderator after that.

I flagged a post and (choose one)   my flag was marked as helpful, yet nothing was done my flag was marked as declined, yet the post was deleted/edited/closed   Why?


Today, after being on StackOverflow for five years, I have discovered the { } button, after reading some blog post. My life was changed.  Well, not exactly, but it did make it a lot easier to indent code in questions asked by SO beginners. Before today, I would copy/paste the code in a local editor, indent, then paste back. That, even though I was visually aware of the button since I clicked the "image" icon to its right many times to paste or insert images.  And I'm .  Proposal  One way to alleviate the problem is to make said code button less easy to overlook. How can we make it more easily discoverable?   Move it towards the left (except for right-to-left sites) in the toolbar, based on its frequency of use. I'd guess that it's the most useful tool, perhaps after the link tool. B and I I think are rarely used, because it's comparatively much easier to just type * or _ before and after the text.   This move could be applied only on code-related SE sites. If the { } button were placed before B, it would be hard to miss, while B and I would be also highly visible (and familiar from the toolbars in many other editors). A slight, subtle, one-time emphasis on the code button (just like the one we have when landing on an anchor, a fading out light orange border - ), for first-time users, perhaps when unindented code is detected (we already have an ). After the button is clicked for the first time, the user's profile would store a flag indicating that the emphasis should not be repeated.   Notes   The argument that there's a shortcut key for the code button misses the point - a user who doesn't see the button on the toolbar won't mouse over it to learn the shortcut key from the tooltip. They're also less likely to venture in the help and learn about that shortcut key. History - A previous related proposal has implemented an , but only for users under 50 rep, which some moderators  is too low of a limit - "I think the reputation limit it too low. I've seen poorly formatted code from people with much higher reputation. –  ChrisF♦ Jul 13 '11 at 12:35"

One feature of SO that pains me every single time is having to manually indent all code four spaces, and usually copy four spaces to the clipboard so Ctrl+V acts as 'Tab'.  Maybe it's on purpose to stop walls of code, but I want to discuss it anyway because everything else seems to go so smoothly and this annoys me and slows me down every day.  ....  And I JUST found the 'code block' feature after many months (having looked through a similar question or two).  I guess then can I rephrase as, 'Please make the CODE BLOCK editor feature/button more obvious' ?


I don't see why why I should be warned about being made unable to ask or answer for deleting questions and answers I've put up when they have been deemed off-topic and closed, or voted down and become "protected" by Stack Exchange moderators.

Given the recent number of users who come here to complain that their account has been suspended because they deleted too many of their own questions, could a warning message be added after the first deletion which points to the policy "Your account will be suspended if you delete too many questions"?  Or even a simple: "Are you sure you need to delete this questions? "  Update: See also the  results for many examples of users who were suspended.


I have looked at many questions regarding this but none have solved my issue. I am using a template to write my thesis and want to change the size of my paper but am unable to do so with the command:     \documentclass[letterpaper, 12pt, oneside]{Thesis}   I have tried the following as well     \usepackage[letterpaper]{geometry}   but that ends up changing the formatting of the document and puts all the written content to the top left hand of the page.

Quick question to anyone who has used this LaTeX template:    Any ideas on how to change the left margin to get more words onto one page?


In oracle an empty varchar2 and null are treated the same because Oracle internally changes empty string to NULL values. Please consider  following example :  --1- create table CREATE TABLE persons(     person_id NUMBER GENERATED BY DEFAULT AS IDENTITY,     first_name VARCHAR2(50)  ,     last_name VARCHAR2(50)  ,     PRIMARY KEY(person_id) );   --2-insert sample data insert into persons (first_name,last_name) values('n1','l1'); insert into persons (first_name,last_name) values('n2',null); insert into persons (first_name,last_name) values('n3',''); insert into persons (first_name) values('n4');    the following query has result :  select * from persons where last_name is null;  PERSON_ID FIRST_NAME      LAST_NAME                                             2      n2                                                                                3      n3                                                                                4      n4          and      select * from persons where last_name is not null;     PERSON_ID FIRST_NAME       LAST_NAME                                   1      n1                  l1        My question :   1-Why this queries result are “no rows selected”  select * from persons where last_name =''; --   no rows selected select * from persons where last_name !=''; --  no rows selected   2-More important question is wonderful behavior for the following query:  select * from persons where last_name !='' or last_name =''; --  no rows selected

I know that it does consider ' ' as NULL, but that doesn't do much to tell me why this is the case.  As I understand the SQL specifications, ' ' is not the same as NULL -- one is a valid datum, and the other is indicating the absence of that same information.  Feel free to speculate, but please indicate if that's the case.  If there's anyone from Oracle who can comment on it, that'd be fantastic!


Please help, in this sentence is "a number" an attribute or the subject of the sentence?

Formally, is it correct to write:     A number of questions has been asked here.   or:     A number of questions have been asked here.   As a non-native speaker of English, I would prefer the former: the subject seems to be "number", therefore the verb ought to be singular, I'd say. However, the latter seems more common, and therefore I believe that my gut feeling is just plain wrong — but I would really like to have a definite answer.  Moreover, is it the same for "a myriad of", "a plethora of", and so on?


Why does it take longer for an object thrown upwards to fall back down than it does for it to reach its highest point? We can draw a free body diagram for when the object is falling down and for when it's going up, but what does that tell us? Is there a simple argument for this or does one need to solve a differential equation? I first learned of this phenomenon during my first semester of physics but apparently I never really understood why it occurs.

A ball is shot directly upward, and then it comes back to the place where it was shot. Suppose we have air resistance. Suppose $t_1$ is the time period from the moment that the ball was shot to the moment that it reached its highest altitude, and $t_2$ is the time period from the moment it reached its highest altitude to the moment it reached its original position. Is $t_1=t_2$? Why or why not?


I am working on the problem:     If G is a group of order 2n, show that the number of elements of G of order 2 is odd.   which already has solution (in the link below), please explain the solution in that link

I am working on the following problem from group theory:     If $G$ is a group of order $2n$, show that the number of elements of $G$ of order $2$ is odd.   That is, for some integer $k$, there are $2k+1$ elements $a$ such that $a \in G,\;\; a*a = e$, where $e$ is the identity element of $G$.


Supposed I have 3 resistor, R1=1 Ohm, R2=2 Ohm, R3=3 Ohm. I connect them with copper wire to form a ring R1-R2-R3-R1 I used a device to generate changing magnetic flux in that ring. So there must be induced current flow in the ring. The problem is if I measure voltage between two ends of R1, what would that voltage be ? Since it is closed circuit then Ohm law indicate that I  *R1 = I * (R2+R3) EDIT: As suggested in comments, this question duplicate

The circuit shown below consists of two resistors connected in series that form a closed loop. No electrical sources are in that loop.Let’s assume that the resistance of the wires that connect the resistors and form the loop is zero.Inside the loop is an external changing magnetic field that induces inside that loop a constant EMF of 1 V.   The current inside the loop is calculated using Ohm’s Law :  The problem was introduced by former MIT professor Walter Lewin. The problem was introduced in this video (starting at 35th min of the video):  In the video is shown that two voltmeters connected to the same terminals show different values. Can two voltmeters connected to the same terminals show different values? My solution to this problem would be: To measure the voltage between points D and A, the circuit has to be divided into two halves, the left half of the loop and the right half of the loop. If the induced EMF is considered to be equally distributed through the loop then in every half of the loop there is an induced EMF of 0.5 V:  The polarity of the the induced EMFs is according to Lenz law.  The voltage between points D and A by writing the equation trough the left half of the loop is:  The voltage between points D and A by writing the equation trough the right half of the loop is:  The conclusion is that there is a unique voltage value between points D and A, and the measured value should be 0.4 V. Now let’s connect to the circuit between points D and A two voltmeters. The two connected voltmeters together with the wires that connect them to the main circuit form a second loop. Let’s assume that the resistance of the wire that connects the voltmeters and forms the second loop is zero. The left half of the second loop is connected to the voltmeter between points C and B, the right half of the second loop is connected to the voltmeter between points F and E. There is also an induced EMF of 1V inside the second loop. If the induced EMF is considered to be equally distributed through the second loop then the final circuit can be represented with the model shown on below.  The voltage between points C and B is defined with the following equations:  The voltage between points F and E is defined with the following equations:  The calculations above match the measurement performed by professor Walter Lewin. My main question is : What is the theoretical potential difference between points D and A?


Here is the command:     opam init  Here is the error I am getting:     bash: /use/local/bin/opam: cannot execute binary file: Exec format error  Are there any suggestions on what we should try?

I'm trying to run a program, but an error happens like this:  bash: ./program: cannot execute binary file: Exec format error   The result of file program was:  program: ELF-32-bit LSB executable, ARM, EABI4 version 1 (SYSV), dynamically linked(uses share libs), for GNU/LINUX 2.6.16, not stripped   How can I fix this error?  I'm using Ubuntu 14.04.2 (amd64) with VMware. I also tried with Ubuntu i386, but result was same.


Let us, initially, analysis only a two dimension situation. Assume that $F(x,y)$ is a force dependent on the particle position (give by $x,y$) is proposed that if   \begin{equation} \frac{\partial \frac{\partial F_x}{\partial x}}{\partial y} = \frac{\partial \frac{\partial F_y}{\partial y}}{\partial x} \end{equation}  where $F_x$ is the component of the force in $x$ axis and $F_y$ is the component of the force in $y$ axis.     The proposition is: If the equation above is true to the force $F$ then this force is  and we can write a potential function associated with this force.    Is this proposition true?  Remembering that the equation above is the same of say:  \begin{equation} \frac{\partial \frac{\partial (-U)}{\partial x}}{\partial y} = \frac{\partial \frac{\partial (-U)}{\partial y}}{\partial x} \end{equation}  implying for example that the work done by this force in any path does not depend on the path only in the initial and final positions..  in this lecture one can see better what is asked:

There are several conditions that must be met in order for a force to be . One of them is that the curl of that force must be equal to zero? What is the physical intuition behind this? If you can, please explain it to me via the magnetic force fields because i have read that time-varying magnetic fields are not conservative because they do not meet that condition.I do not understand this.


You might have heard of the  that has never been fixed (). Essentially you can't printscreen while a menu is active. Today, I was working with two monitors, vscode in one and the browser on the other. I right clicked on the vscode text editor to open the . While opened, I tried taking a rectangular screenshot using Ctrl+Shift+PrtScr and click-and-dragged on the vscode app to select the screenshot region. Then BAM. Not only it didn't work, but the whole UI became buggy. I couldn't click anything anymore, I tried Ctrl+Tabing sometimes and I was eventually able to click on the browser, but the rest is still unresponsive (side and top menus aren't clickable, vscode isn't clickable...) I feel this bug is just getting worse with time, and it's kind of mindblowing it has never been fixed. Is there any known workaround for this?

I need to capture a drop-down menu of a program. If I open the menu and then press PrntScr (print screen button), it first closes the menu and then captures the screen. I tried Ctrl+PrntScr, Shift+PrntScr, Alt+PrntScr but no success. I am using Ubuntu 14.04.


I experienced a bug in "meta.stackoverflow.com" site.  Steps to reproduce:   Visit "MyLogins", for me, it is:  Click "add more logins…", then it redirects to:  Try to use any login method on that page, and get redirected to:    It says "Page Not Found".

I've seen this behavior on multiple meta sites, for example:        As soon as you choose to add a new login (To be honest I only tried Google, Facebook and the OpenId box), you get redirected to a 404 page at [meta site url]/users/authenticate. .  In my opinion, since when trying to login (i.e. first time login) on a meta site it redirects to the login page of its main, the "Add more logins" page on meta should also redirect to its main "add more logins" page. I think this would just make it more consistent.


We can use same logic for both types (string/bigint) to generate consecutive ids (e.g. like ). This way both are naturally sortable. So, let's say we have a value 30722102503933550. What is the real performance difference if we would leave it as bigint (30722102503933550::bigint) vs using as a string ("30722102503933550"::text) for a primary key.

I am developing an application in Ruby on Rails with the PostgreSQL (9.4) database. For my use case, columns in tables will be looked up very frequently, as the whole point of the application is searching for very specific attributes on a model.  I am currently deciding whether to use an integer type or simply use a typical string type (e.g. character varying(255), ) for the columns, as I'm not sure what the performance difference will be on the index.  These columns are enums. They have a fixed size for the amount of possible values they can have. Most enum lengths do not exceed 5, meaning the index would be more or less fixed throughout the lifetime of the application; thus, the integer and string indexes would be identical in the number of nodes.  However, the string that would be indexed could be around 20 characters long, which in memory is roughly 5x that of the integer (if an integer is 4 bytes, and the strings are pure ASCII at 1 byte per character, then this holds). I don't know how database engines do index look-ups, but if it needs to "scan" the string until it matches exactly, then in essence that means that the string lookup would be 5x slower than an integer lookup; the "scan" until match for the integer lookup would be 4 bytes instead of 20. This is what I'm imagining:  The lookup value is (integer) 4:     scanning............................ FOUND | getting records...   |BYTE_1|BYTE_2|BYTE_3|BYTE_4|BYTE_5|BYTE_6|BYTE_7|BYTE_8|...|   The lookup value is (string) "some_val" (8 bytes):     scanning.....................................................................................   FOUND | getting records...   |BYTE_1|BYTE_2|BYTE_3|BYTE_4|BYTE_5|BYTE_6|BYTE_7|BYTE_8|...|   I hope that that makes sense. Basically, because the integer takes up less space, it can be "matched on" faster than its string counterpart. Perhaps this is a completely wrong guess, but I'm no expert, so that's why I'm asking you guys! I suppose that  seems to support my hypothesis, but I want to be sure.  The number of possible values in the column wouldn't change in using either one, so the index itself would not change (unless I added a new value to the enum). In this case, would there be a performance difference in using integer or varchar(255), or does using an integer type make more sense?    The reason I am asking is that Rails' enum type maps integers to string keys, but they aren't meant to be user-facing columns. Essentially, you can't do verification that the enum value is a valid one, because an invalid value will cause an ArgumentError before any validations can be run. Using a string type would allow validations, but if there's a performance cost I'd rather just hack away around the validation problem.


I am trying to run a fixed effects logit-regression in R using glm() as follows glm(binary_outcome ~ as.factor(region)*as.factor(birth_cohort) + as.factor(region)*as.factor(gender)+as.factor(birth_cohort)*as.factor(gender)+treated:as.factor(gender)-1, data, family = "binomial") This gives the following error "Warning message: glm.fit: algorithm did not converge" Also, in other contexts, if I get something similar to run, the estimates don't make sense and the standard errors are huge (in the order of 10+e8). I suspect the problem is multicollinearity, so I am wondering, if glm() knows, how to normalize the fixed effects regression, since this obviously needs normalizations. If not, is there a simple way to specify it?

I'm trying to predict a binary outcome using 50 continuous explanatory variables (the range of most of the variables is $-\infty$ to $\infty$). My data set has almost 24,000 rows. When I run glm in R, I get:  Warning messages:   1: glm.fit: algorithm did not converge   2: glm.fit: fitted probabilities numerically 0 or 1 occurred    I've read the other responses that suggest perfect separation might be occurring, but I'm confident that isn't the case in my data (though quasi-complete separation could exist; how can I test to see if that's the case?). If I remove some variables, the "did not converge" error might go away. But that's not always what happens.  I tried using the same variables in a bayesglm function and got the same errors.  What steps would you take to figure out exactly what's going on here? How do you figure out which variables are causing the problems?


I have 5 files called file1, file2, file3, file4, file5, . I am attempting to run the following command echo "contents" >> file{1,2,3,4,5}. I get the following error when I run this command; -bash: file{1,2,3,4,5}: ambiguous redirect. My goal is to echo some text to multiply files in one command. How can I achieve this? Thanks in advance.

How to redirect standard output to multiple log files? The following does not work:  some_command 1> output_log_1 output_log_2 2>&1


If one were to list several exclamatory quotations within a single sentence, where and how do commas fit in?  For instance;    "When children are on my lawn I like to yell, "Get away you mangy kids!", "I'm going to call the police again!", Here comes the garden hose!", "I know where you live!", or something to that effect."  Do the commas belong outside the quotation marks, inside following the exclamation mark, or do they not belong at all?

I recently learned that I have developed a consistent, but entirely wrong approach to punctuating direct speech in fiction. I am in the unenviable position of trying to relearn.  Previously I wrote such things as:     "I'm done." She said.   when the quoted speech was definitely, absolutely the end of a sentence. So now I know I need.     "I'm done," she said.   This follows the rule that a period is only allowed when the end of the spoken sentence is also the end of the sentence in the narrative. For example:     "I'm done." She slammed the door on the way out.   So, it now looks odd to me when there are multiple sentences in the speech:     "I can't take her. I'm done," she said.   Can you reassure me that is correct, or give the correct form? Please don't suggest rewriting the sentence to put 'she said' in the middle - I'm aware of that: I'm specifically asking about the punctuation rules.  The other odd case is speech ending with an ellipsis. Do sentence terminating ellipses (four periods normally) become:     "I can't take her. You know, ...," she said, nodding towards Jane.   If so, are non-terminating ellipses dealt with the same way?     "I can't take ...," she nodded towards Jane, "any more!"   or can non-terminating ellipses be used unadorned?     "I can't take ..." she nodded towards Jane, "any more!"   I'd be very grateful if you could point me at references as well as answers. For the record I am a British writer writing for both British and US publication, so any variation is also interesting to me!


I found this kind of magnet key ring:    Is it safe to attach one end to an USB stick?

I know it is possible to wipe a hard disk, but I'm wondering if something similar can be done to SSD disks as well?


Does anyone here know why Hunter x Hunter chapter 350 has not been released yet?  When is it coming out? I would be grateful for any answers or comments you are able to provide.

I think the Hunter x Hunter manga has been on hiatus for months now; does anyone know the reason for the hiatus? Is the author planning to continue the series?


Let $F$ be a field of characteristic $p > 0$.  Show that $(\alpha + \beta)^{p^m} = \alpha^{p^m}+\beta^{p^m}$, for all $\alpha,\beta \in F$ and $m > 0$.  I am stuck on this question; can anybody help?

Prove that if $F$ is a field with $p^n$ elements and $\alpha,\beta \in F$, then   $$(\alpha + \beta)^{p^n} = \alpha^{p^n} + \beta^{p^n}$$   From Newton identity, we have that $$(a + b)^n = \sum_{i = 0}^n \binom ni a^i b^{n - i}$$ However, I'm already stuck because in a finite field we cannot necessarily compute the binomial, since we may divide by zero. How do I get around this?  Furthermore, since $F$ has characteristic $p$, isn't it $p^n = 0$? How does it make sense in the first place? I'm a bit confused.


suppose we have a vector $x \in \mathbb{R}^{n}$, and a closed convex set $C \in \mathbb{R}^{n}$. $C =\{x|Ax=b\}$  how to calculate the vector $y \in \mathbb{R}^{n}$, which is the projection of $x$ onto set $C$. The vector $y\in C$ and have the smallest distance to $x$.

Suppose $A$ is fat(number of columns > number of rows) and full row rank. The projection of $z$ onto $\{x\mid Ax = b\}$ is (affine)        $$P(z) = z - A^T(AA^T)^{-1}(Az-b)$$       How to show this?       Note:  $A^T(AA^T)^{-1}$ is the pseudo-inverse of $A$   What I am thinking is from:   Least square problem:  $$\text{min $\left\|\: Ax-b \,\right\|_2$}$$ The solution for this is $\hat{x} = A^T(AA^T)^{-1}b$. It seems $(Az - b )$ above is the role of $b$ here.   Vector projection of $x$ onto $y$:    $$p = \frac{x^Ty}{y^Ty}y$$      But I still cannot figure out how to prove the above result.


Permittivity can be described as the opposition of an electric field (and accordingly flux) by a medium through which the field passes. I understand this opposition is generally produced by dipole moments of the atoms within the medium, but in the absence of these atoms and thus the dipole moments (as in free space), what causes the opposition?  In other words, what opposes an electric field in a vacuum and gives rise to $\epsilon_0$, the permittivity of free space?

When light travels through a material, it gets "slowed down" (at least its net speed decreases).  The atoms in the material "disturb" the light in some way which causes it to make stops on its path.  This is expressed in the material's permittivity and permeability:  Its ability to transmit electromagnetic waves.  But then what causes the limited permittivity and permeability of vacuum?  There are no atoms there to disturb the light, so what is keeping it from travelling at infinite speed?  Is there a special property of space itself which determines the speed of light?  Or is it the virtual particles in vacuum which interact with the light?


I know 'come tuesday' or 'come spring' are correct (or I think I do). But can I say for example 'come the end of the world' or, when I'm driving my car and a tire blows out, 'come one of the tires blow out'? I'm not a native English speaker and google isn't helping one bit. So I'm hoping someone can shine some light onto this mysterious 'come-business' for me. Thanks in advance!

I’ve stumbled upon the following sentence reading a blogpost:     Come C++11 (programming language) there are some extra options for our ownership policies.   What does come mean here? It doesn’t look analogous to any clause I’m aware of.  (Well, I understand the general meaning of the sentence but I don’t understand how come in such a syntactic form fits in here. If anything (maybe the blog author was incorrect?), the sentence means that after C++11 has come there are those options.)


I've been learning about the Lagrangian formulation recently, and while I'm with the process, I am still struggling somewhat with the theory behind it. As I (rather poorly) understand it, the formulation is based on the principle of least action. The Euler-Lagrange equation is used to find the minimums of the integrals of the Lagrangian (the action), which is then used to solve for whatever value you are interested in.   What I DON'T understand is why the Lagrangian is equal to the difference between the total kinetic and potential energy of the system. The definition seems arbitrary. What is the significance of that particular difference? Every lecture I've found seems to brush past the point, and I've yet to find a satisfying explanation. Can anyone provide a better justification?

Is there a proof from the first principle that for the Lagrangian $L$,    $$L = T\text{(kinetic energy)} - V\text{(potential energy)}$$  in classical mechanics? Assume that Cartesian coordinates are used. Among the combinations, $L = T - nV$, only $n=1$ works. Is there a fundamental reason for it?  On the other hand, the variational principle used in deriving the equations of motion, Euler-Lagrange equation, is general enough (can be used to to find the optimum of any parametrized integral) and does not specify the form of Lagrangian. I appreciate for anyone who gives the  answer, and if possible, the primary source (who published the answer first in the literature).      Notes added on Sept 22: - Both answers are correct as far as I can find. Both answerers were not sure about what I meant by the term I used: 'first principle'. I like to elaborate what I was thinking, not meant to be condescending or anything near to that. Please have a little understanding if the words I use are not well-thought of. - We do science by collecting facts, forming empirical laws, building a theory which generalizes the laws, then we go back to the lab and find if the generalization part can stand up to the verification. Newton's laws are close to the end of empirical laws, meaning that they are easily verified in the lab. These laws are not limited to gravity, but are used mostly under the condition of gravity. When we generalize and express them in Lagrangian or Hamiltonian, they can be used where Newton's laws cannot, for example, on electromagnetism, or any other forces unknown to us. Lagrangian or Hamiltonian and the derived equations of motion are generalizations and more on the theory side, relatively speaking; at least those are a little more theoretical than Newton's laws. We still go to lab to verify these generalizations, but it's somewhat harder to do so, like we have to use Large Hadron Collider. - But here is a new problem, as @Jerry Schirmer pointed out in his comment and I agreed. Lagrangian is great tool if we know its expression. If we don't, then we are at lost. Lagrangian is almost as useless as Newton's laws for a new mysterious force. It's almost as useless but not quite, because we can try and error. We have much better luck to try and error on Lagrangian than on equations of motion. - Oh, variational principle is a 'first principle' in my mind and is used to derive Euler-Lagrange equation. But variational principle does not give a clue about the explicit expression of Lagrangian. This is the point I'm driving at. This is why I'm looking for help, say, in Physics SE. If someone knew the reason why n=1 in L=T-nV, then we could use this reasoning to find out about a mysterious force. It looks like that someone is in the future.


I have forgotten my Gmail account password and the phone number, Gmail is asking for sending a code,  is also deactivated. So how could I open my Gmail account?

I have forgotten the password or username for my Google account, or I'm unable to access my account for other reasons.  How can I recover my account?  (This Q&A is meant as a general description for all Google and Gmail username/password questions. See: )


I have a dedicated 240 volt circuit that's hard wired into my air conditioning unit.  The circuit has a 30 amp breaker at the main box and another 30 amp breaker on the wall next to my air conditioner.  Since the main breaker box is on the opposite side of the house from the garage, another run would be price preclusive.  Instead, I am considering the install of a switch (e.g. DPDT Center-Off) like the Leviton 1288:   (see figure 3)  The goal is to keep the circuit dedicated - regardless of which load it is directed to (i.e. air conditioner OR NEMA 14-30).  The NEMA 14-30 would be used in the garage for charging an electric vehicle.  The air conditioning unit is outside (just on the other side of the wall).  Two questions:   Does this use case violate NEC code? Is DPDT a reasonable choice for this use case?   Another answer in the forum (slightly different question) stated that it is 'more elegant' to switch the Neutral wire (since it too is a conductor).  I have not been able to locate a wiring diagram depicting Neutral with a DPDT.  What's the scoop?

I've got a situation where I have a 240V 30A dryer line, and I want to power something else from the same circuit, but NEVER at the same time as the dryer. I'm looking for a switch to use, like a DPDT ON-ON break-before-make switch. There are tons of DPDT switches I've found, and most seem to be ON-OFF. Hardly any show their wiring diagrams, so if they don't give more details, I don't know if they'll work. Note: the second circuit will not use more than 15A, maybe just 12A.  I'm hoping someone can recommend specific switches that will do what I want. Manufacturer and exact part# is what I'm looking for.   Personally, I don't care if it's a knife switch, something that looks like a standard light switch, two buttons, has relays, I don't care. The breaker box is full, it's a long and difficult wire run, and I do not need a separate circuit because I'll NEVER need to run both devices at once.  I could resort to just using one plug and unplugging one then plugging the other one in, but I don't see the point of constantly exposing live wires (the plugs) where something could inadvertently fall on them or water could be sprayed, instead of keeping things all sealed in the wall with a safe, simple switch between two plugs.