We are given an  infinite nested radical as follows  $$\sqrt{1+\sqrt{2+\sqrt{3+\cdots}}},$$  which can be proven that it is convergent, namely, is equal to a real constant.  For this purpose, we consider applying the monotone convergence principle. Since its monotone property is obvious, what we need is to show it is bounded above.  First, we claim      $${\frac{n}{2^{2^{n-1}}}\leq 1(\forall n)}$$   $Proof~~~~$ It's easy to show $2^{n-1}\geq n.$ For $n=1,2$, it holds trivially. For $n \geq 3$, by Newton's binominal theorem, we have $$2^n=(1+1)^n=\binom n0+\binom n1+\cdots+\binom n{n-1}+\binom nn\geq 1+n+n+1\geq 2n.$$ Thus $2^{n-1}\geq n$. Furthur, $2^{2^{n-1}}\geq 2^n \geq 2^{n-1}\geq n,$ which implies ${\dfrac{n}{2^{2^{n-1}}}\leq 1(\forall n)}$.  Next, we claim     $${ \sqrt{1+\sqrt{1+\sqrt{1+\cdots}}}<\infty}.$$   This is a well-known result. In fact, substituting $1$ among here for any $a>0$, it's also true. For the recursion $x_1=\sqrt{a},x_n=\sqrt{a+x_{n-1}}(n\geq2)$, we can show that $a_n\leq a$, just by mathematical induction.  Now, go back to the present problem. Notice that  \begin{align*} \sqrt{1+\sqrt{2+\sqrt{3+\cdots}}}&=\sqrt{2}\cdot\sqrt{\frac1 {2}+\sqrt{\frac2{2^2}+\sqrt{\frac3{2^4}+\cdots}}}\\ &\leq\sqrt{2}\cdot\sqrt{1+\sqrt{1+\sqrt{1+\cdots}}}\\ &<\infty, \end{align*}  which is desired.  But, my question is that, can we evaluate it? In another word, can the limit be expressed as an elementary closed form?


I am upgrading my 14.04LTS Ubuntu to 16.04. The problem is that it's been at the same step (Configuring openssl amd64) for like 20 hours. I tried to get to the terminal to know what is happening but the terminal just doesn't open. In Xterm I ran a few commands to resume the installation since Possibly my laptop lost connection and typed in XTerm:  $ sudo apt-get install -f which displays Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-fronted), is an other process using it? Which is understandable for the somewhat frozen upgrading process. Then I typed:  sudo screen -D -r But the screen: is not found Sutting down my laptop is not an option here since I do not want to ducplicate packages. Also, installing a virtual machine to run something remote I am not sure how to do it. Can this be fixed from the XTerm? Thanks in advance and looking forward to your replies.

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


I am trying to look for a source of clean Shapefiles in .shp format with country borders, for every country around the globe.  Would you be able to point me to an online free source?

I need the names of countries, country regions and cities of the world.  Where do I get that kind of information?


var numbers = [1, 5, 10, 15]; var doubles = numbers.map(function(x) {   return x * 2;   //doubles is now [2, 10, 20, 30]   I am following this above example, This is working for a constant 2, how can I mulitply the elements with variable this.price,  var numbers = [1, 5, 10, 15]; var doubles = numbers.map(function(x) {    return x * this.price;   How can I make this works? this.price is a public variable.

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


I am new to C++ and I'm reading a book called Big C++. In the book, all of the example programs I've seen so far end with return 0; before the final }. I can apparently make C++ programs run without return 0; at the end, so I'm wondering what purpose it serves. I am familiar with returning something from a method in java, but I don't understand why int main() would need to return 0 in C++. To get more to the point: Should I always end my main() with return 0; in C++? If not, when do I need to and when shouldn't I? What is return 0; telling the program to do?  In a related question, I am assuming that the main() in C++ is setting up the main function like the main method in java. Is that correct? Why is the main method being declared as an integer? Is that what is happening in the line int main() {?

What is the correct (most efficient) way to define the main() function in C and C++ — int main() or void main() — and why? And how about the arguments? If int main() then return 1 or return 0?  There are numerous duplicates of this question, including:       — For C++, with a very good answer indeed.     Related:


In linux:  I can open a folder via xdg-open command from terminal. Then define a keyboard shortcut to any a combination of key to open a common used folder. e.g ctrl + shift + c to open the dir /home/me/note/cs  On mac:  I can open a folder via open /path/to/dir from terminal. But is it possible to define a shortcut so that I can open a specific dir with a specific shortcut?

What are the options which would be faster than opening Finder and browsing the folder, to open it?  (I like to keep the desktop completely clean so will avoid Desktop shortcuts if other options are available)  Usually what happens with me is that there are a few folders (favorites?) which I need to open very frequently like multiple times a day and almost daily (and get landed to some other folder while browsing through Finder).  Can imagine something like 'pinning' to the Finder icon on the Dock could be of great help, like one can pin favorite folders on the taskbar on Windows.  What do you do to quickly go to your favorite folders?


On Call of Duty: Black Ops 2 the controller goes down when I want to go up and up when I want to go down. How do I fix this?

When I play Black Ops 2, it seems that my xbox controller is inverted. Example: if I press up, my character looks down and vice versa. It was not like this before. Does anyone know how to reset the controller back to its original settings?


I have a string named "var" where the text string is set as doc1, doc2 or doc3  String var = "doc2" // doc1 or doc2 or doc3   I get content from the website using Jsoup this way  Document doc_comp = Jsoup.connect("http://www.computer.org").get();                     Elements doc1_comp  = doc_comp.select("ul > doc1" );                                         Elements doc2_comp  = doc_comp.select("ul > doc2" );         Elements doc3_comp  = doc_comp.select("ul > doc3" );   I use switch case for the corresponding values to be printed         switch(var)         {         case "doc1": System.out.println(doc1_comp.text());         break;         case "doc2":System.out.println(doc2_comp.text());         break;         case "doc3":System.out.println(doc3_comp.text());         break;         default: System.out.println("no info");         }   Everything works perfectly fine with the switch case but I want to use a single line of code to replace switch case like this  System.out.println(var.concat("_comp.text()"));   but it straight away prints as a string "var_comp.text()" but does not execute it and print the content inside it.  Is there a way around to make it run

If I have two variables:  Object obj; String methodName = "getName";   Without knowing the class of obj, how can I call the method identified by methodName on it?  The method being called has no parameters, and a String return value. It's a getter for a Java bean.


I want to know if is there any programme to download music from YouTube, not video, just audio, like DVDvideosoft in Windows.

There are several Q&A threads that explain how to download youtube videos using the terminal.  However, I would also like to learn how to extract the video's soundtracks as MP3 files--also using only the terminal.  Answers briefly explaining how to use youtube-dl or other similar utilities before explaining how to extract the MP3 would be ideal for the sake of having all the information in one place--even though this aspect has been covered in other posts.


I've been dealing with C++ strings and currently I am wondering how can I split the article of a string and the data that's left.  Let's say I have this string:  a gold coin   How can I split the article which in this case is a into a separate string and then get all the other data contents into a different string which in this case is gold coin?  Please note that the article can sometimes be an and sometimes have no article.  Edit I am not trying to split strings from a space token I am splitting special words from the string in condition for extracting a pronoun article name and the pronoun string.

I'm trying to iterate over the words of a string.  The string can be assumed to be composed of words separated by whitespace.  Note that I'm not interested in C string functions or that kind of character manipulation/access. Also, please give precedence to elegance over efficiency in your answer.  The best solution I have right now is:  #include <iostream> #include <sstream> #include <string>  using namespace std;  int main() {     string s = "Somewhere down the road";     istringstream iss(s);      do     {         string subs;         iss >> subs;         cout << "Substring: " << subs << endl;     } while (iss); }   Is there a more elegant way to do this?


I need the current time with nanosec. As string "%.9f" % float_time it is 1502872986.653693676. You can see 76 at the end. If I try to write the same time as int int(float_time*10**9), it will be 1502872986653693696 and 96 at the end. Why? And which is the right way to get nano format?  from time import time  float_time = time() print("float_time:", float_time) int_nano_time = int(float_time*10**9) print("int_nano_time:", int_nano_time) str_nano_time = "%.9f" % float_time print("str_nano_time:", str_nano_time)      float_time: 1502872986.6536937      int_nano_time: 1502872986653693696      str_nano_time: 1502872986.653693676   Solution:  time.monotonic()      float_time: 536596.296      int_nano_time: 536596296000000      str_nano_time: 536596.296000000

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


I was going through some old code that I'd been using, and knew worked because it was still functioning. I was, however, confused when I found I'd written a <?, but not <?PHP. And yet, the code after that still worked. Is this defined? Is this supposed to work like this? Have I been writing slightly more code than I could be? It feels dirty to leave off the PHP, but if it's okay, I might as well, right?    Sandbox:

Here's the information :     There are four different pairs of   opening and closing tags which can be   used in PHP. Two of those, <?php ?>   and <script language="php"> </script>,   are always available. The other two   are short tags and ASP style tags, and   can be turned on and off from the   php.ini configuration file. As such,   while some people find short tags and   ASP style tags convenient, they are   less portable, and generally not   recommended.   In my experience most servers do have short tags enabled. Typing  <?=   is far more convenient than typing  <?php echo    The programmers convenience is an important factor, so why are they not recommended?


I am extremely new to LaTeX so this question will definitely make me look like a newbie. I'm attempting to put in two images into a report. The first one was placed exactly where I wanted it and it looks good. The second image does not fit onto the page and so it vectors it onto the next (which is completely fine). The issue is that it automatically places the image into the middle of the next page, which I don't want. I would like it to be at the top of the page. Here is my code: \begin{figure}[hbt!] \centering \includegraphics[width=\textwidth]{Images/CvsT.png} \caption{C vs. T} \label{fig:inputs} \end{figure}  Any help is greatly appreciated.

I just got a short algorithm on my page, and it keeps getting aligned at the center of the page. But I want to have it aligned at the top, what do I have to do?


Currently on SO there are 2 identical pairs of 2 identical tags:    (11,957)      POST is one of the HTTP protocol methods;      (2,195)      POST is one of the HTTP protocol methods   Please merge and synonymize [post] into [http-post].  Same for  (4,720):     HTTP GET is a request method   and  (456):     GET is one of many request methods supported by the HTTP protocol.   I think http-* is more readable thus should be a master tag.

When I say "get", what does it mean to you? A GET request? To retrieve something? To query a database? To call the get method on a C# property?  appears to encompass all of those and more. We should either burn it or split it up.  However, splitting it up would just result it . For the SQL query, we already have . Ultimately, most should questions should be retagged .  Its tag wiki suggests that it is for the HTTP GET protocol, however, there are quesions tagged with  that don't fit that description. A manual retag might be the only solution with ~375 questions tagged with it. There are also some that have both the  tags. The fact that you need two to describe the question shows that they really should be changed to .  As suggested by RiaD, maybe use . We could maybe burn  and replace it with ?


I'm having issues with a clean local install of 4.3, my admin is broken and it seems a JS issue. Please check the attached screenshot. No plugins or themes are installed.  Anybody is experiencing the same? No error in console either. I tried both in Chrome and Firefox.

I'm having an issue with my admin menu in WordPress. As you can see in the image below the formatting of the menu is out of order. This happens whenever I first land on one of the admin pages but if I refresh the page the menu looks fine. I tried disabling my plugins but none of them seem to be causing the issue.


New Mac Machine is asking apple id on start up of machine is it really required or mandatory to have an apple id to start with this? if so can i create an apple id without providing any credit card info?. Please guide this newbe...

I bought my mother an iPad 2 as a gift for her birthday, hoping that it would enable my toddler son to do Facetime with his grandmother.  I tried to walk her through the activation process (over email) by having her download iTunes to her Windows laptop, etc.  She managed to do that much, but when the activation process asked her to create an Apple ID and give a credit card number, she refused to proceed.  I can't imagine that she would even buy an app, or music, or a book.   I thought the device would be worth it just for mobile Safari, Facetime, and the other built in apps.  Is it possible to activate the device without creating an Apple ID?  If not, is it possible to get around the credit-card number field?


My logrotate works perfectly, except for this configuration:  /var/awdata/awarchive.*.log  /var/log/awstats.log  {         rotate 12 }   This is my logrotate -d /etc/logorate.conf output:  considering log /var/awdata/awarchive.domain1.it.log    log needs rotating   and then:  rotating log /var/awdata/awarchive.domain1.it.log, log->rotateCount is 4 dateext suffix '-20120517' glob pattern '-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]' fscreate context set to unconfined_u:object_r:var_t:s0 renaming /var/awdata/awarchive.domain1.it.log to /var/awdata/awarchive.domain1.it.log-20120517 creating new /var/awdata/awarchive.domain1.it.log mode = 0666 uid = 99 gid = 501   logrotate seems to work perfectly, but it does not do what I wrote. :-(  ==  ls -lah /var/awdata/*domain1*   About domain1:  -rw-rw-rw-. 1 nobody nogroup 4.7G May 17 17:16 /var/awdata/awarchive.domain1.it.log -rw-rw-rw-. 1 nobody nogroup 7.6G May  9 04:16 /var/awdata/awarchive.domain1.it.log-20120509   The only rotate log *-20120509 was forced with the -f option.  [root@lnx1 awdata]# ls -ld /var/awdata drwxr-xr-x. 2 nobody nogroup 188416 May 17 18:52 /var/awdata   Any ideas?

I have this logrotate config and I am running on Ubuntu 10.04.  /var/log/mysql/mysql-slow.log {     daily     rotate 3     compress     notifempty     missingok     create 660 mysql adm     postrotate      if test -x /usr/bin/mysqladmin && \        /usr/bin/mysqladmin  ping &>/dev/null     then        /usr/bin/mysqladmin  flush-logs     fi endscript   }  I put this in /etc/logrotate.d yesterday and today the log was not rotated.  Below are the things that I have done:   I verified that the log is indeed in /var/log/mysql/mysql-slow.log  mysqladmin lines work fine when run as root mysql is able to write to the mysql-slow.log   When I did this:  $ logrotate -d -f mysql-slow  reading config file mysql-slow reading config info for /var/log/mysql/mysql-slow.log   Handling 1 logs  rotating pattern: /var/log/mysql/mysql-slow.log  forced from command line (3 rotations) empty log files are not rotated, old logs are removed considering log /var/log/mysql/mysql-slow.log  log needs rotating rotating log /var/log/mysql/mysql-slow.log, log->rotateCount is 3 dateext suffix '-20120329' glob pattern '-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]' renaming /var/log/mysql/mysql-slow.log.3.gz to /var/log/mysql/mysql-slow.log.4.gz     (rotatecount 3, logstart 1, i 3),  renaming /var/log/mysql/mysql-slow.log.2.gz to /var/log/mysql/mysql-slow.log.3.gz (rotatecount 3, logstart 1, i 2),  renaming /var/log/mysql/mysql-slow.log.1.gz to /var/log/mysql/mysql-slow.log.2.gz (rotatecount 3, logstart 1, i 1),  renaming /var/log/mysql/mysql-slow.log.0.gz to /var/log/mysql/mysql-slow.log.1.gz (rotatecount 3, logstart 1, i 0),  renaming /var/log/mysql/mysql-slow.log to /var/log/mysql/mysql-slow.log.1 creating new /var/log/mysql/mysql-slow.log mode = 0660 uid = 20004 gid = 4 running postrotate script running script (multiple) with arg /var/log/mysql/mysql-slow.log : "      if test -x /usr/bin/mysqladmin && \        /usr/bin/mysqladmin &>/dev/null     then        /usr/bin/mysqladmin flush-logs     fi " compressing log with: /bin/gzip removing old log /var/log/mysql/mysql-slow.log.4.gz    Where is the log that shows that logrotate was successful? I want to see if there is anything that would say that there was a problem. Any ideas on why the logrotate is not working?


Let $A$ be a set that is countable. Let there be a function mapping $A$ onto a set $B$. I'm asked to prove the statement "$B$ is countable".   This is my attempt at a solution.   Since $A$ is countable it is either finite or countable infinite.  If it is finite the statement is obvious. If it is countably infinite, it is by definition in one-to-one correspondence with the set $N$ consisting of positive integers. Since there exists a function mapping $A$ onto $B$, every element in $B$ has a direct relation to atleast one element in $A$, which in turn has a relation to $N$. And thus it $B$ must be countable since by proxy it is in one-to-one correspondence with $N$.  Does this logic prove anything, am I missing something? Am I completely on the wrong track and if so, how would I go about proving it? What happens in extreme cases if every element in $B$ is the image of a lot of elements in $A$?

Is my logic correct/accepted?   Let A be a countable set. Let f:A->B, surjective. $\exists$g:A->N, bijective. Using definition from 1. $\exists$h:N->B, surjective. $\therefore$B is countable by definition using 4.   Am I allowed to assume #4? Does anything need to be cleared up?


I have heard that no one escape from the intense gravitational field of a black hole (obviously that's why it is black). And gravitational force is due to the mass having the body, no mass no gravity, as  $$F=GMm/r^2$$ Putting $0$ in one of the two bodies' masses, gives no gravitational force.  But light cannot escape from black hole due to its strong gravity, does that mean that light has mass? please correct me.

I understand that a black hole bends the fabric of space time to a point that no object can escape.   I understand that light travels in a straight line along spacetime unless distorted by gravity. If spacetime is being curved by gravity then light should follow that bend in spacetime.  In Newton's Law of Universal Gravitation, the mass of both objects must be entered, but photon has no mass, why should a massless photon  be affected by gravity in by Newton's equations?  What am I missing?


If I install a software by executing:  ./configure make make install    Is there a generic way to uninstall it (like sudo apg-get remove)?

I used source code to build one package such as below:  ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --libexecdir=/usr/lib --with-package-name="Myplugin" --with-package-origin="http://www.ubuntu.org/" --enable-gtk-doc --disable-static make make install   But unfortunately, i discovered that its the latest version, and has lot of bugs, so i need to remove it/uninstall it. But how can i do so? I tried make clean; make uninstall but still i see it exist:  # pkg-config --list-all | grep Myplugin myplugin-.... $ ls /usr/lib/myplugin/libXYZ.so exist....   How do you remove this now?


An extremely deadly/hostile atmosphere on a planet/moon/asteroid is being exploited (mined?) by biological avatars controlled from orbiting ships. The protagonist begins to lose the distinction between his avatar "self" and "reality".

Humans in a spaceship orbiting an alien planet have a machine that they can hook their heads up to that lets them take telepathic control (and receive the senses of) of massive (I think at least something like Rhinoceros-size) six-legged leonine creatures on the planet below. Not direct muscle control -- the creature just feels an intense desire to go in the direction the orbiting human in the headset wants it to go. The main human character, stays in daily contact with one creature over a few weeks. The main character gradually realizes through the link that the creature being coerced to travel to a coast (far outside of its usual hunting range) is actually intelligent.  The feline-like aliens don't see with eyes, instead having IR-sensing plates, I think perhaps due to a perpetually darkly overcast atmosphere.  At the end the main chracter actually meets the creature in person, I think (a shuttle touches down on the coast). I don't remember why the humans were there -- research? Maybe prospecting for resources? The planet was not remotely hospitable to humans -- I think it was either too dense, too hot, wrong gas mix, or some combination.  I had a copy of the paperback book that someone gave me, that was missing the front cover (maybe they got it from a book store's discards that are supposed to be pulped), but on the back was a picture of the snarling or roaring face of one of the creatures, black-furred like a panther. I think it was a gray- or silver-background cover.  This book would probably have been from the 1990s or 1980s.


I was playing with datatypes in python.  Every time, when I do  remaining_amount  = .1 + .1 + .1 - .3 python gives an exponential result.  I try to do the same with c#  double remainingAmount = .1 + .1 + .1 - .3  It is also giving result in exponential form. In both cases, the result is 5.55111512312578E-17  But in c#, when I change double to decimal, the result is 0.0  I am unable to understand why this is happening in both languages.  And how can I fix this in python?

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


Here's a sample of my csv file  5,DENTISTRY,MAJOR,null,TRUE 6,DERMATOLOGY,MAJOR,null,TRUE 7,"EYE, EAR, NOSE, THROAT",MAJOR,null,TRUE 8,EMERGENCY MEDICINE,MAJOR,null,TRUE   How do I split this csv file while ignoring the comma inside double quotes?

Can anyone recommend a simple API that will allow me to use read a CSV input file, do some simple transformations, and then write it.  A quick google has found  which looks promising.  I just wanted to check what others are using before I couple myself to this API.


I want to back up some files on an external disk. I won't be accessing the files as often, but I want them to be secure and private. It goes without saying that I don't want to upload them on the cloud, I want them offline.  So my question is, are HDDs suitable for long term storage, or are SSDs better in this regard? What are the variables that I need to consider?

Okay,  which was closed as being too localized and I understand the idea of that closure: Systems, environments and usage are all different. But my question is about using SSD for minimal write use, archival purposes. Meaning, instead of storing tapes, optical media (BluRay, DVD-R, DVD-RAM, etc…) or even a hard drive somewhere safe, what about SSD which uses NAND flash memory for storage? I assume the act of simply plugging in an SSD, copying data and then tossing the drive in safe/secure archival space disconnected from a system is a solid (no pun intended) way of storing long term data? I have worked with institutions that routinely archive things on hard disk drives in such a way. But as we all know a hard disk drive is one drop away from being wiped out. SSDs seem inherently much more resilient.  seems to state that modern SSDs — even those used on a daily basis — will outlast their own self-professed max lifetime. The reason I am asking this now is SSDs on a very basic consumer level are very cheap nowadays with — for example — 120GB SSDs going for as low as $40, I believe these things would be a good long term storage for things such as archived photos, videos and such… And will only get cheaper as time goes on.


A good friend just installed a new hardrive in my daughters old Toshiba Satellite L355D, which she passed on to me. I'm retired and looking to expand my old age horizons. This friend gave me a disc witb Lumbuntu 14.04.2 on it to download to is new hardrive. I've done that part and accepted/loaded all the updates the system asked for.  The most computer experience I've had was with Windows Vista and 7 at the job I retired from. I do have an iPhone and an Android Kit Kat tablet that I manage to use fairly well. I'm looking for some basic, low tech oriented instructions for this Lumbuntu OS. Preferably something I can access and read from my tablet? This friend was really exited for me to start using this OS. He said its lite weight and made for beginners like me.

I've just started using Lubuntu 13.10. It's the first time I've ever used Linux.  Can any of you send me a tutorial-video for new users or explain the basics to me?


In the Middle Earth universe, "Wizards" are actually Maia, angelic or  beings who have taken mortal form (and accepted some Human frailties) to act as guides and advisors in the struggle against Sauron.  They have specialties (or at least personal preferences), determined by their association to whichever Vala they serve.  Within Middle Earth they appear as aged Men with long beards, wearing robes of colors which denote their rank.  And they each carry a staff.    Why?  If they are, themselves, semi-divine beings, then presumably all their powers (even in the abstract way that magic works in Tolkien's universe) come from their own selves, rather than from any devices.  I've never heard of any tales about the "forging of the staves," and no one seems to be able to gain greater power by taking them. (At least, no one seems to try, and Sauron would likely be seeking them if their powers were transferable.)   Broken or lost staves , but at the same time, the loss of one seems to be significant for the Wizard who loses it:   In the movies, at least, Saruman is implied to have greater power when he takes Gandalf's staff and uses it along with his own during their fight in Orthanc, though that fight doesn't exist in the books.  (Notably, this would indicate that a staff's power IS transferable, at least between the Istari.) Wormtongue insists that the guards of Meduseld "take the Wizard's staff" when Gandalf arrives. Given that Wormtongue is in league with Saruman, he would presumably know whether this would have any effect on Gandalf's abilities, and he clearly thinks it would. Gandalf makes a special effort to retain his staff when entering Meduseld, confirming that losing it would have an effect on his abilities. Gandalf prominently declares "Your staff is broken!" when Saruman is defeated, as though it is an important, even ceremonial, act. The destruction of his staff seems traumatic for Saruman, perhaps even somewhat painful from he way he gasps for breath.     What is the function of the staff for one of the Istari?  What does it allow them to do, that they would not otherwise be able to do?  Is it a way of exercising their Maia-level abilities, when they are otherwise restricted to their mortal forms?  Or are they a device crafted after the arrival of the Istari, sort of like the Rings, to expand and augment their natural magic?  What do we know about the staffs of the Wizards?  Note: I've read , which focuses on Gandalf's relative strength with and without the staff.  This question is more general than that: what does the staff even do, and where do they come from?

Before Gandalf freed Théoden from Saruman/Gríma's hold, he refused to give away his staff.      Háma: I cannot allow you before Théoden King so armed, Gandalf Greyhame... by order of Gríma Wormtongue.   [Gandalf nods, and they hand over their weapons]   Háma: Your staff.   Gandalf: Oh... you would not part an old man from his walking stick?     After that, while he was breaking theirs hold on him, Gríma shouted to the guards      His staff! I told you to take the wizard's staff!   But what if he was denied the use of his staff? How much of his power is tied to his staff? Is he harmless/defenseless without his staff? If his staff is taken by an other magically capable being, how much of Gandalf's power would it have?


I selected Eclipse from within USC and clicked the 'Use this source' button. The 'Progress' icon whirls for a few seconds, and then I get a message box:  Failed to download repository information  W:Failed to fetch http://security.ubuntu.com/ubuntu/dists/quantal-security/main/source/Sources  404  Not Found [IP: 2001:67c:1562::17 80]   Why won't it download?

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


I'm doing a problem about arranging people into groups, and having watched Numberphile's video on partitions recently, I'm trying to use partitions to solve it.   Is there any way to find the number of partitions which have a certain number of elements?  For example, one can sum to $4$ in only one way using 3 positive integers: $\{2, 1, 1\}$.  Is there any way to find the number of ways of doing this for numbers $n \leq 20$?  Thank you.

For a fixed $n$ and $M$, I am interested in the number of unordered non-negative integer solutions to $$\sum_{i = 1}^n a_i = M$$  Or, in other words, I am interested in the number of solutions with distinct numbers. For $n = 2$ and $M = 5$, I would consider solutions $(1,4)$ and $(4,1)$ equivalent, and choose the solution with $a_1 \ge a_2 \ge ... \ge a_n \ge 0$ as the representative of the class of equivalent solutions.  I know how to obtain the number of total, ordered, solutions with the "stars and bars" method. But unfortunately, I cannot just divide the result by $n!$ since that would only work if all the $a_i$ are distinct.


I have never used this software before. My dad unexpectedly passed away one week ago today. His computer is locked. Me and my siblings want to gain access to see if there are pictures, any last words, letters anything. How can we unlock without a password? Can we at all? Who would I even go to about it to try? I’m lost and just looking for answers.

I'm working on a Ubuntu system, and my client has completely forgotten his administrative password. He doesn't even remember entering one; however it is there.  I've tried the suggestions on the website, and I have been unsuccessful in deleting the password so that I can download applets required for running some files. Is there a solution?


This table  \begin{tabular}{ | l | l | } \hline Ausdruck & Wert \\ \hline int x = 49; & -- \\ \hline !(x >= 0 \&\& x < 50 || x > 50 \&\& x <= 100) & true \\ \hline x++ == 49 || x-- == 49 & false \\ \hline !(x >= 0 \&\& x < 50 || x > 50 \&\& x <= 100) & true \\ \hline int k; scanf("\%d", \&k); & -- \\ \hline !(k > 0 \&\& k\%10 <= 7) == (!(k > 0) || !(k\%10 <= 7)) & true \\ \hline \end{tabular}   produces the following result:    Issues   > is output as ¿ < is output as ¡ || is output as ——   It should look like    Any suggestions on how to put those code snippets inside the table?

When typing < or > in LaTeX and compiling with pdflatex, the less than and greater than symbols appear at upside down exclamation points. I'm not in math mode.


Why does this inequality hold?  $$(x+y)^\alpha \leq x^\alpha + y^\alpha$$  where $x$, $y\geq 0$ and $\alpha \in (0,1)$.  Thanks in advance!

If $p,q$ are positive quantities and $0 \leq m\leq 1$ then Prove that $$(p+q)^m \leq p^m+q^m$$    Trial: For $m=0$, $(p+q)^0=1 < 2= p^0+q^0$  and for $m=1$, $(p+q)^1=p+q =p^1+q^1$.   So, For $m=0,1$ the inequality is true.How I show that the inequality is also true for $0 < m < 1$.   Please help.


I have been just introduced to the term tensor while studying Rotational Dynamics, particularly about Inertia. But I just don't get a clear line separating vector from a tensor. What does someone mean when stating a particular physical quantity as a tensor quantity?

Physics texts like to define vector as something that transform like a vector and tensor as something that transform like a tensor, which is different from the definition in math books. I am having difficulty understanding this kind of definition. To me, it goes like this:   First we have a collection of bases or coordinate systems (do these represent reference frames?) and the transformations between them. A vector/tensor is an assignment of an array of numbers to each basis, and these arrays are related to each other by coordinate transformations.   I am wondering how coordinate systems and transformations are specified.    Do we need all possible coordinate systems and transformations to define a vector space or just a few of them? How to define the concept of basis and coordinate transformation without completing the very notion of vector?


I have a list of spheres with some known characteristics (ids, radii, masses, and positions) with ids, radii, and masses being 1D arrays with shape (511, ) and positions being 3D array with shape (511, 3) inside some big spherical volume with known center, (0, 0, 0) and radius, distance_max. hal_ids_data = np.array([19895, 19896, ..., 24249])                    hal_radiuss_data = np.array([1.047, 1.078, ..., 3.263])                  hal_masss_data = np.array([2.427e+06, 8.268e+06, ..., 8.954e+07]      hal_positions_data = np.array([np.array([-33.78, 10.4, 33.83]), np.array([-33.61, 6.34, 35.64]), ..., np.array([-0.4014, 4.121, 33.05])])  I would like to randomly place these tiny spheres throughout the volume within the big sphere while keeping their individual characteristics intact meaning only their positions need to be shuffled subject to two constraints shown below. for hal_id, hal_position, hal_radius, hal_mass in zip(hal_ids_data, hal_positions_data, hal_radiuss_data, hal_masss_data):      # check if 1) any one of the small spheres are above some mass threshold AND 2) inside the big sphere     if ((np.sqrt(pow(hal_position[0], 2)+pow(hal_position[1], 2)+pow(hal_position[2], 2)) < distance_max) and (log10(hal_mass)>=1e8)):          # if so, then do the following stuff down here but to the shuffled populations of small spheres meeting the conditions above rather than to the original population  What is the fastest and shortest numerical algorithm to shuffle my small spheres under the last if statement before doing some stuff on them? (I do need my original population info though for later use so I cannot disregard it)

The present question follows on from some other questions on this site asking how to generate uniform points inside a disc (see e.g., ,  and ).  The natural extension of that problem is to generate points inside an $m$-dimensional   with centre $\mathbf{c} \in \mathbb{R}^m$ and radius $r \geqslant 0$.  That is, we want to generate IID random variables from the following distribution: $$\mathbf{X} \sim \text{U}(\mathcal{B}(\mathbf{c},r)) \quad \quad \quad  \mathcal{B}(\mathbf{c},r) \equiv \Big\{ \mathbf{x} \in \mathbb{R}^m \Big| ||\mathbf{x} - \mathbf{c}|| \leqslant r \Big\}.$$ How do we generate IID uniform points on this space?  Is there a simple way to program this?


I tried using partial fractions to compute the sum of the series $$ \sum_{n=1}^{\infty}\frac{1}{n(n + 1/3)} $$  Another technique is to turn this series into a definite integral of 0 to 1. but do not know how to do.    Thanks for any help.

A while ago, I started to look at expressions of the following form: $$ S_p:=\sum_{n=1}^\infty \frac1n - \frac1{n+1/p}, $$  where $p$ is prime, because otherwise things get too complicated for me at the moment.  What I found so far is the following: $$ S_p= p -\log(2p) - \frac12 \pi \cot\left(\frac\pi p\right) + T_p, $$ where $T_p$ contains $\frac{p-1}2$ terms $t_{p,k}$ of the form:  \begin{cases} \pm 2 \sin\left(\frac{k\pi}{2p}\right) \log\left(\sin\left(\frac{k\pi}{2p}\right)\right) \\ \pm 2 \cos\left(\frac{k\pi}{2p}\right) \log\left(\sin\left(\frac{k\pi}{2p}\right)\right)\\ \pm 2 \sin\left(\frac{k\pi}{2p}\right) \log\left(\cos\left(\frac{k\pi}{2p}\right)\right)  \\ \pm 2 \cos\left(\frac{k\pi}{2p}\right) \log\left(\cos\left(\frac{k\pi}{2p}\right)\right)  \end{cases}   An example can be found .     How does the closed form for $\sum_{n=1}^\infty \frac1n - \frac1{a+n}$ look like? (EDIT: where $a=1/p$)


I am new to Javascript event handling, today I have encountered an issue for click event,
        some more stufff    <button onclick='remove(1,1);'>remove</button>
   Now, When I click on the button, the remove functions called then the editField function too. I know why it called...  I want to prevent the editField function when the button gets clicked.  Thanks in advance!

Consider the following:
   something inside the header
   How can I make it so that when the user clicks the span, it does not fire the div's click event?


How can i access the Linux machine remotely ? That means i want to access my friend laptop which is booted with ubuntu16.04, and my laptop also booted with ubuntu16.04. what and all softwares i want install and send the procedure too

How do I remotely control another desktop (both are Ubuntu 12.04) from my client machine?  Is it possible to use Remmina Remote Desktop Client?


I am trying to make a login system in java by using the result that a page gives me when getting the page's content over java like when i get the data from       http://localhost/java.php?un=dubking&password=password   when the login credentials are correct that page will only show "true" as html but when i use the array that has the data from that page wich actually has "true" in it in an if statement the if statement doesn't work, is there something I did wrong or is this just not possible in Java?  import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.MalformedURLException; import java.net.URL; class test2 {     public void calc() {         try {              URL yahoo = new URL("http://localhost/java.php?un=" + username + "&password=" + password);              BufferedReader in = new BufferedReader(                      new InputStreamReader(yahoo.openStream()));              String inputLine;               while ((inputLine = in.readLine()) != null) {                  // Process each line.                 String html = inputLine;                 if (html == "true") {                     System.out.print("You have successfully logged in.");                 } else {                     if (html == "false") {                         System.out.println("Wrong username or password.");                     }                     if (html != "true" && html != "false") {                          System.out.println("something went wrong.");                         System.out.println(html);                     }                 }             }              in.close();           } catch (MalformedURLException me) {              System.out.println(me);           } catch (IOException ioe) {              System.out.println(ioe);          }       } }

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?


Suppose that we have irreducible polynomials over a field, $f,g\in F[x]$, and that $g$ divides $f$ in $L[x]$ where $L$ is a field containing splitting fields of $f$ and $g$ over $F$. Can we say that $g$ divides $f$ in $F[x]$? I've got this question from the following proof: "If there is finite group $G\subseteq \text{Aut }E$ satisfying $F=\text{Inv}(G)$ then $E/F$ is a Galois' extension." Considerations:  $f\in F[x]$ irreducible; $r$ such that $f(r)=0$; $\mathcal{O}_r=\left\{\sigma(r):\: \sigma\in G\right\}=\left\{r_1,...,r_m\right\}$; $g=\prod (x-r_i)$.  The author concludes that $g$ divides $f$ in $F[x]$ immediately after showing that $g\in F[x]$. But I don't consider that so trivial. I proved that it's true because if $f=gh$ for some $h\in L[x]$ then $\widehat{\sigma}(h)=h$ for any $\sigma\in G$ where $\widehat{\sigma}\:\colon E[x]\to E[x]$ is the unique ring homomorphism mapping $a\mapsto \sigma(a)$ and $x\mapsto x$, hence $h\in F[x]$. Is there any forward way?

I would like to verify the validity of the following line of thought:  Let $K \subset E$ be a field extension. Let $K[x]$ be the polynomial ring over $x$ and denote $K(x)$ its field of quotients (the rational functions over $K$).  Now assume $f(x)=g(x)h(x)$ with $f(x),g(x) \in K[x]$ and $h(x) \in E[x]$ and all $f$, $g$, $h$ are different than zero. Then $\frac{f(x)}{g(x)} = h(x)$ in $E(x)$. So $h(x) \in K(x)$. But $h(x)$ is a polynomial, so $h(x) \in K[x]$.  Is there any other simpler argument than that?  Added:  Let me be more specific. Let $x^p - a \in K[x]$, with $p$ being prime and $char(K)=p$. Let $b$ be the unique root of $x^p - a$ in its splitting field $K(b)$. Then $x^p - a=(x-b)^p \in K(b)[x].$ Let $m_b(x) \in K[x]$ be the minimal polynomial of $b$ over $K$. Then $m_b(x)$ divides $(x-b)^p$ and so $m_b(x)=(x-b)^l$ and $l$ is the smallest positive integer for which $(x-b)^l \in K[x]$. Let $p = lq+r$ where $0 \ge <l$. Then $x^p-a=(m_b(x))^q (x-b)^r$. Can i conclude that $(x-b)^r \in K[x]$ and so $r=0$ by the minimality of $l$?  Thanks.


Could not find any sources talking about this (in a clear manner). If the Na+ / K+ ATPase pumps 3 Na+ out for every 2 K+ it pumps in, thus making the cell more negative, why is the Na+ / K+ ATPase used to restore resting membrane potential following hyperpolarization? Wouldn't that must make the cell more negative, which is the opposite of what we want?

(Firstly, I know this is similar to other questions, but I have read those answers and they do not really cover this topic).  My understanding of resting potential: action potential is not being transmitted; by way of action potentials via Na+ and K+ pumps, for every 2K+ pumped in, 3Na+ is pumped out of the cell. This process is termed "resting potential" and the transmembrane pd roughly = -65mV.   If more Na+ are pumped out than K+ in, why does the resting potential difference remain at -65, why does it not continue to decrease (until an action potential is triggered)?


I newly installed Ubuntu alongside Windows on my laptop and no connection to the internet is available.  Ubuntu Version should be the newest and I am new to Ubuntu and wanted to get some experience in it. I tried e.g. sudo apt-get update and other suggested commands but no packages (so every installation doesn't work) were found and connections to some http-resources failed also, because the site couldn't resolve.  Any hints for the solution would be awesome!  If any information is needed, just let me know  Output of lspci | grep -i network:  03:00.0 Network controller: Broadcom Limited BCM43228 802.11a/b/g/n

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


In the Last Jedi,       Holdo ran the Raddus into the First Order fleet at light-speed,  doing massive damage.    Why has no-one thought of this before?  Fit a light-speed drive to a cheap ship, and make your own super missile. You could even fill it with a warhead for added damage. Why is it not a standard tactic?   Not only do you have incredible tactical speed advantage (compare this to the slow projectiles as the FO fleet shot at the Raddus, and it even looks faster than energy bolts), but it seemed to ignore the shields.

This question is related to "The Last Jedi":  The maneuvre that vice admiral Holdo (with the purple hair) uses towards the end of the film seems remarkably effective.   It seems that it would have worked pretty well much earlier. Especially as two other ships were just allowed to run out of fuel and be destroyed.  It seems doing it earlier with different assets would have incurred less losses. Yet nobody seemed to consider it. Any in universe reason why?


A few months ago I installed ubuntu alongside windows and everything was working fine. However I only gave the ubuntu partition ~7GB of memory, thinking I wouldn't use it as much. Long story short, turns out I needed a lot more memory for it, so I completely wiped my hard drive, merged all the various partitions I had and started from scratch. I first installed windows. While doing that, from the windows installer I created 3 partitions. 1 - Windows (~300GB), 2 - Various stuff (~50GB), 3 - Ubuntu (~350GB). I installed windows on the first partition with no problem whatsoever. But when I tried to install ubuntu on partition 3, it popped an error saying:   "/dev/sda contains GPT signatures indicating that it has a GT table.      However it does not have a valid fake msdos partitiontable as it should. Perhaps it was corupted possibly by a program that doesn't    understand     GPT partition tables or perhaps you deleted the GPT table and are now using an msdos partition table.Is this a GPT partition table?"   I am pretty new to the world of "partitioning" so I have absolutely no idea what any of that means. So, any kind of help would be immensely appreciated. But please, PLEASE, remember that I'm a newbie to all that stuff, so I probably won't understand very technical solutions. If you kept it simple, you'd have my never ending gratitude.  Thank you in advance.  EDIT: I forgot to mention something I think is rather important. When I try to create a partition using the ubuntu installer, it says that I have ~685GB of unallocated space. (I have a 700GB hard drive, so it thinks it's completely empty). I think it doesn't recognize any of my current partitions.

/dev/sda contains GPT signatures indicating that it has a GPT table. However, it has a fake msdos partition table as it should. Perhaps it was corrupted? Is this a GPT partition table?  So, that's the error message and this is during my first OS install of Ubuntu. Can close the message box. Can't click yes and can't click no. What do I do?


If I were to disagree with an opinion, how should I write it in a respectful and idiomatic way? Normally I would write;  "Tinged with regret, I respectfully disagree."  Are there any other phrases or expressions to differ in opinion?

My classmate told me I should always say, "With all due respect," or "I politely disagree," when disagreeing someone - especially an educator - in order to avoid being perceived as rude.  For example:     Teacher: This class always infuriates me. Most of you are either absent or   late for my class. I will give you all failing grades in this subject!      Me: With all due respect Ma'am, many of my classmates actually do attend your class, and arrive early, to learn something about your subject. I think you should take all those students who attend your class on time and daily, into consideration.   or      Teacher: There's a higher incidence of suicide in men than women because men choose to hide their suffering or pain without telling anybody.      Me: Ma'am, I politely disagree with this opinion. According to the most recent studies of the American Psychiatric Association about suicide, more women attempt suicide than men, although men seem to be more successful in their attempts, resulting in more fatalities.     Can you suggest some polite variations?


I am trying converts a Fahrenheit degree to Celsius.Now I have a Error,When I use this:  double fahrenheit=input.nextDouble();  double celsius= ( **5** /9)*(fahrenheit-32);(Error)   Then again I am trying given (5.0) then it is work why?

Here's an example:  Double d = (1/3); System.out.println(d);   This returns 0, not 0.33333... as it should.  Does anyone know?


I'm a student taking a real analysis course at university. I'm working down my problem sheet and have been asked the following (which is the full version of the shortened question in the title).  Q:Suppose $f:[0,2 \pi] \rightarrow \mathbb{R}$ is a continuous function satisfying $f(0) = f(2 \pi)$. Show that there is a number $c \in [0,\pi]$ such that $f(c) = f(c+ \pi)$.  The question seems to be referencing $\sin(x)$. A solution I know exists in the range $[0, \pi]$ is $c=0$, therefore $\sin(0)= \sin(\pi)$. However $\sin(x)$ doesn't appear to be directly referenced and I am not sure how to show a value for $c$ only knowing $f(0) = f(2 \pi)$.  If anyone can help it would be much appreciated!

Suppose that $f$ is continuous on $[0, 2\pi]$ and that $f(0) = f(2\pi)$.  Prove that there exists a $c$ in $[0, 2\pi]$ for which $f(c) = f(c+\pi)$.  Here is what i did: if $f(c) = f(c+\pi)$, then $f(c) = f(c-\pi)$.  $f(c+\pi) = f(c-\pi)$ for which $\lvert{\sin(x)}\rvert$ is the function that comes to my mind, and I'm stuck here. I must use the mean value theorem and maybe Rolle's theorem since it's a question from that section, but $\lvert{\sin(x)}\rvert$ is not differentiable. Yet the question itself doesn't mention anything about differentiability of the function. Could anyone solve this, please?


I spent some time fixing up the formatting for  and it was automatically rejected.  Is it because the question has several downvotes?

Why does the Community user sometimes approve or reject edits? How does a machine know if my edit is valid? What does it mean if my edit was rejected by Community?     See also:


just had a quick question.  Should be a simple fix.  When I am trying to bring in HDRs for lighting, it seems to not be scaling or working properly.  I can't see the HDR in the background.  I have kind of fiddled around with it by trying to use texture coordinate and mapping in the world section of the node editor but nothing was working.  It appears that the HDR is still lighting my scene for the most part but it's all thrown off.  Here is a screenshot of what it looks like.  You'll notice there is some blue in the background, but that's not very helpful.  Also, you can see what the HDR looks like in the preview area on the properties editor.  Thanks for the help!

I have added a background image to the world settings. However, it has disappeared from my 3D view and only shows when I view the scene from the camera. Does anyone know if there is something I can do to make it reappear?


I'm listing the customers names on my webpage with PHP retrieving data from MySql, but some of them are called José, João, but when I echo the result on the page, it shows Jos� and Jo�o. The collations of the tables are all on utf8_general_ci what can I possibly be doing wrong??

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


How can I formally evaluate the following integral?$$\int_{1}^5 \frac{\log(7-x)}{\log((7-x)(x+1))}dx.$$ I tried the substitution $t=\log(7-x)$ and the integrand reduces to  $$\frac{-te^{t}}{t+\log(8-e^{t})},$$ although this does not look much simpler.  According to Wolfram, the answer appears to be $2$.  I am not sure how this can be obtained; perhaps there is some elegant trick that I am missing, because the result is unexpectedly simple.

How can I find the value of this following definite integral?     $$\int_2^4\frac{\sqrt{\log(9-x)}}{\sqrt{\log(9-x)}+\sqrt{\log(3+x)}}dx$$


If this rather trivial I apologize. How we can embed very quickly a video (mp4) in a beamer slide? From what I have seen I cannot figure out the proper way.  I tried with the multimedia package (following this ) but it din't work. (The slides will be in pdf format. I use Adobe reader XI.)  \documentclass{beamer} \usepackage{multimedia} \begin{document} \begin{frame}{myvideo} \movie[]{}{video.mp4} \end{document}

I have written the following document  \documentclass[aspectratio=1610]{beamer}  \usetheme[hideallsubsections]{Berkeley} \useinnertheme{rounded} \usepackage{multimedia} \title[]{{\scshape Infodag wiskunde}} \date{{\scshape 16 maart 2013}}  \begin{document}  \begin{frame} \titlepage \end{frame}  \begin{frame}\label{chaosfrag1}\frametitle{{\scshape Chaos 1 - }} \begin{center} \movie[showcontrols]{\includegraphics[width=0.8\textwidth]{chaos1.png}}{chaos1.mpg} \end{center} \end{frame}  \end{document}   For some reason however, neither Adobe Reader nor Foxit PDF Reader are able to display the movie on click. I figured the issue was probably with the pdf readers, but last year I made a similar document, and though I no longer have the TeXcode, I still have the pdf, and this does work. (the embedded media there is also .mpg). I already tried different media types (.avi, .mp4, .flv) but none of them work.  I know about the media9 package, however, as my final document will contain about 18 movies of each 10 minutes, the resulting pdf would be 2GB. Whenever I open it, it takes at least 10 seconds to start playing the media, and even then, it doesn't work (I just get a gray rectangle).  EDIT: Okay, appearantly i was using a wrong code for media9, so now I can play the video (though the filesize still is huge). But still, it would be nice to see if I made a mistake somewhere in the \movie command or something...  I hope someone can help :)


I've deleted all my sub Stack Exchange sites, like . I do not have any profile now. I wish to delete my main account as well. But there is no such option to remove it. I want to completely remove any account associated with my email, but the main account itself doesn’t seem to allow to be deleted ever if everything else was deleted. I need help! Note: I had to create a meta account for this.

Stack Exchange seems to have made it impossible to delete accounts. I can delete the accounts from other individual sites like Ask Ubuntu, but I can't delete the main account on stackexchange.com. I want to be rid of Stack Exchange completely! I don't want a Stack Exchange account whatsoever! I really don't like Stack Exchange and I want nothing to do with it. Please help me delete my stackexchange.com account!


I currently read a java book and I am stuck at an example including this line :  Bird titi = new Swan();   where Swan is a subclass of Bird.  I could explain this as follow:     when java executes this line, it stores memory for the value titi, and the memory stored can contain an information for an object of type Bird. next, the second part of the line call the Swan constructor without any argument, which initializes the titi value.   if I am right, I can't explain why a Swan instance can be stored in a Bird type because Swan, as a subclass, contains more information than Bird. so I think I am something wrong. where?  and, extra-question : in which case this type of statement is useful?  thank you

In terms of Java, when someone asks:      what is polymorphism?   Would overloading or overriding be an acceptable answer?  I think there is a bit more to it than that.   IF you had a abstract base class that defined a method with no implementation, and you defined that method in the sub class, is that still overridding?  I think overloading is not the right answer for sure.


Consider areas in Mathematics such as Percolation Theory, Reliability Engineering, Reliability Theory, Theoretical Physics, Theoretical Computer Science, Algebraic Geometry — do I write the names with a capital letter or with small letters?

Do I say "I study computer science," or "I study Computer Science"? Similarly, "I really liked that computer science course," vs. "I really liked that Computer Science course."


In iOS 11, I can't disable Bluetooth or Wi-Fi using the redesigned Control Center. It disconnects from any Bluetooth/Wi-Fi devices but the radios are still on, draining battery. It also doesn't disable AirDrop either. If I disable Bluetooth or Wi-Fi using settings this shows:     How can I quickly disable Bluetooth/Wi-Fi without having to go to settings?

I'm facing this issue after updating iOS11 in my recently bought iPhone 7  I usually turn off wifi during the night and found it ON in the morning. It automatically turns ON resulting in unnecessary battery drains.  Would appreciate a fix !!


I am using Debian 9 (stable) and I recently decided to install mingw-w64 so that I could do cross platform C/++ development since I don't have consistent access to a Windows machine. When I had first installed it a couple days ago to test out doing 32 and 64-bit builds, it seemed to work but now the 64-bit command (x86_64-w64-mingw32-gcc) seems to only put out 32-bit executables despite the fact that it should only put out 64-bit by default. I even explicitly declared the options -m64 and -march=x86_64 in an attempt to force it, but it seems like no matter what I try now it will only do a 32-bit build.  For reference, all the code consists of is three files: hello.c, hellofunc.c, and hellofunc.h. The file hello.c simply calls a function defined in hellofunc.c called printHelloWorld:  void printHelloWorld(void){     long z;      printf("Hello World!\n");      switch(sizeof(z)){         case 4:             printf("This program is 32-bit\n");             break;         case 8:             printf("This program is 64-bit\n");             break;         default:             printf("This program is of unknown bit size\n");     }       printf("Long int size is %i bytes long!\n", sizeof(z)); }   With the expected output being "This program is 32-bit" or 64-bit, with an explicit statement showing the byte length of a long variable. The problem I am having is that despite the fact that the 64-bit mingw-w64 gcc command is being used, when I do test it on Windows it will display the 32-bit message and a byte length of 4 instead of the expected 8.  Again, when I initially tested it right after download it worked as expected and I have no idea what could have changed the default functionality of it over the last couple of days- I didn't install anything new, and all I was doing was trying to work with makefiles (this directory does not contain one though). Also, for the record, the default gcc native to my Debian system works perfectly well with the -m32 and -m64 commands so it's not like my system isn't capable of it and... in fact, if anything, I would expect the behavior to be backwards as Linux seems to require special set-up to do 32-bit builds or run 32-bit programs on a 64-bit machine.  For the last attempt to understand the problem myself I ran the command x86_64-w64-mingw32-gcc -v -o hello.exe hello.c hellofunc.c -I . so that I could get the full command sequence of the compiler, and I also ran gcc on it as well.  is the full output I put on pastebin just for reference. I don't 100% understand the output, but it seriously looks like all the configuration and options should be outputting 64-bit?? I don't know, I'm still pretty new to Linux and still don't entirely understand how to dissect when something goes wrong- especially when something runs counter to the explicitly defined functionality lol.  If somebody could recommend possible fixes for this or alternatives I probably didn't think of, I would really appreciate. I tried Googling for answers before hand, but x86_64-w64-ming32-gcc seems to only ever come up in conversation to tell newbies that it's the obvious default way to compile for 64-bit architecture.  Thanks for reading and any help you can give, cheers~

Not to long ago, someone told me that long are not 64 bits on 64 bit machines and I should always use int. This did not make sense to me. I have seen docs (such as the one on Apple's official site) say that long are indeed 64 bits when compiling for a 64-bit CPU. I looked up what it was on 64-bit Windows and found         Windows: long and int remain 32-bit in length, and special new data types   are defined for 64-bit integers.      (from )  What should I use? Should I define something like uw, sw ((un)signed width) as a long if not on Windows, and otherwise do a check on the target CPU bitsize?


$$ \lim_{x\to 1} \frac{ \sqrt{x} - 1}{\sqrt[3]{x} - 1} $$  I multiply it with:  $$ \frac{ \sqrt{x} + 1}{\sqrt{x} + 1} $$  And I get :  $$ \lim_{x\to 1} \frac{ \sqrt{x}^2 - 1^2}{(\sqrt[3]{x} - 1) * (\sqrt{x} + 1)} $$  But the solution is still division by 0 and not possible, so I think I've made a mistake somewhere..

Consider this limit:  $$ \lim_{x \to 1} \frac{\sqrt x -  1}{ \sqrt[3] x -  1}  $$  The answer is given to be 2 in the textbook.  Our math professor skipped this question telling us it is not in our syllabus, but how can it be solved?


I'm trying to rollback a particular edit on  but for some reason am unable to rollback the edit. I'm getting the below error message when trying to rollback.    I'm trying to rollback from  because that particular edit actually breaks the code comment. Not sure why am unable to roll it back. Can anybody throw some light on this?

I'm getting a "Unable to rollback to the current revision" alert box when clicking on the rollback option of the revision 2 of the post below:    Update: Right now, no error message is shown, but no rollback is made either.  @JasonC (comments) also reports a problem: "Same issue trying to roll back to revision 4 of  (currently at revision 5)"


I was getting all those messages from firefox that I didn't care about:  Gtk-Message: Failed to load module "pk-gtk-module" Gtk-Message: Failed to load module "canberra-gtk-module"   So I killed firefox and restarted it like this:  $ firefox 2>&1 > /dev/null &   As in "redirect stderr into stdout and pipe both of them out into the null".  Unfortunately, those pesky messages didn't disappear. In fact, the terminal window where I started the firefox session into which I am currently typing this question is still producing them.  So the questions are:  Why the above redirection didn't work?  How do I redirect them correctly?

If several redirections are used together, does changing their order make difference?  How shall one understand the meaning of their order? Is the chained channel of redirections built as reading the redirections from left to right, or from right to left?  For example  command 2>&1 > somefile  command > somefile 2>&1   Thanks and regards!


I'm reading mechanics at undergraduate level and I'm wondering if I understand power correctly.  Let's suppose we have mass and we push on it with the constant net force $ \mathbf{F} $ along the positive x-axis (there is no friction.) If $ \mathbf{v_{t_1}}$ is the velocity along x-axis at some time $t_1$ the power is $ \mathbf{F} \cdot \mathbf{v_{t_1}} $   This implies that the power increases with increasing velocity. So after some time $t_2 = t_1 + dt$ it is true that $ \mathbf{F} \cdot \mathbf{v_{t_1}} < \mathbf{F} \cdot \mathbf{v_{t_2}} $  Is this correct?   If so it just feels strange to me as I have earlier thought, in high school, that the power is constant if we apply a constant force on a mass. One of the reasons I think it's strange is that if the velocity of the mass goes to light-speed then a very small push on the mass will change the power dramatically and will cause a big change in the kinetic energy of the mass. Where as if you push, with the same force, on the mass when it has a low velocity it will cause a small change in power and kinetic energy.   If all this is correct then I think it implies that if we want to dramatically change the kinetic energy of an object, we should apply a force on it when the object has a very large velocity. (I don't know how this would turn out in practice though.)

For a constant force, $P=Fv$. I understand the mathematical derivation of this, but this seems to me, intuitively, to be nonsense. I feel that my discomfort with this comes from a fundamental misunderstanding of force and Newton's Second Law, so I'm not really looking for any mathematical explanation. So, to begin:  How is it that a constant force does not add energy to a system at a fixed rate? Consider a rocket burning a fuel at a constant rate. The chemical potential energy should be converted to kinetic energy at a constant rate, that is, $(1/2)mv^2$ should be increase linearly. The magnitude of the velocity of the rocket would then increase at a less than linear rate, implying a nonconstant acceleration and therefore, a nonconstant force/thrust (F=ma).  If force is indeed a "push or a pull," shouldn't that constant rate of burning of fuel yield a constant "push or pull" as well? Clearly not, so I would have to think that, somehow, a given force applied to a certain object at rest would in some way be different than that a force of the same magnitude being applied to that same object in motion. In this sense, is force merely a mathematical construct? What does it tangibly mean, in physical terms? Would a given force acting upon me "feel" differently to me (in terms of tug) as I am moving at differing velocities?  Force being defined as a "push or pull," which is how it has been taught in my high school class, seems rather "handwavy," and maybe that's the issue. It's been troubling me for a couple of weeks and my teacher hasn't really been able to help, so thanks!


I've written a command that takes a number of minutes and formats it like so: Xh Xmin.    The logic of the command works fine, but if I use it in combination with other command or itself, it produces unwanted spacing in front of the text.      The Command    \newcommand{\timeFormat}[1] { \def\hours{} \def\minutes{} \IfInteger{#1} {     \ifnum\intcalcDiv{#1}{60} > 0         \appto\hours{\intcalcDiv{#1}{60}}     \fi     \ifnum\intcalcMod{#1}{60} > 0         \appto\minutes{\intcalcMod{#1}{60}}     \fi     \ifthenelse{\equal{\hours}{}}     {\ifthenelse{\equal{\minutes}{}}         {}         {\minutes min}}     {\ifthenelse{\equal{\minutes}{}}         {\hours h}         {\hours h \minutes min}} }{} }   Dependencies  \usepackage{intcalc} \usepackage{xstring}   Usage  \timeFormat{100}\timeFormat{1}\timeFormat{60}   Result    So far, I haven't figured out how to get rid of the spacing and I've run out of ideas. How can i fix this?

I see that the code in many packages and examples contains percent signs % at the end of (many) lines. What are they used for? Do they affect the parsing of those lines?


I want to create a matrix of list, but when I create the lists inside the matrix it created a linked list, and I don't need that.  A=[[{}]*3]*3 result: [[{}, {}, {}], [{}, {}, {}], [{}, {}, {}]] A[0][2]['h1']=1 result: [[{'h1': 1}, {'h1': 1}, {'h1': 1}],  [{'h1': 1}, {'h1': 1}, {'h1': 1}],  [{'h1': 1}, {'h1': 1}, {'h1': 1}]]   Anyone knows how to avoid this? I need a list inside each field of the matrix.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I am upgrading to 13.10 and discovered my root partition was too small. I used partition editor to shrink my home partition by 2GB. Now I want to take the unallocated space and add it to sda1. I can't figure out how to accomplish this.  (This is an old question where I found an answer - below. It has been suggested that it is a duplicate of , but this isn't exactly the case. I was using gparted but my problem turned out to be connected to the swap.)

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


Disclaimer: The statement may be false, but for now I'm operating under the assumption it's true and trying to prove it.   My workings:  I got a common denominator and expressed it as:  $$\frac{ab^2 + bc^2 + ca^2}{abc} \ge 3$$ $$ab^2 + bc^2 + ca^2 \ge 3abc$$  This is where I'm stuck. I feel as if I keep encountering this same result in various different problems and always am stumped on how to show it is true.   I tried to look at similar problems and it seems AM-GM inequality is the usual line of attack, so using that I reasoned, $$a^2 + b^2 + c^2 \ge 3abc$$, and now I need to establish $$ca^2 + ab^2 + bc^2 \ge a^2 + b^2 + c^2$$  However, this doesn't seem like it'd be true for general positive $a,b,c$.

Suppose $x,y,z$ are real positive numbers, prove that: $$\dfrac{x}{y} +\dfrac{y}{z} + \dfrac{z}{x} \ge 3$$ with equality when $x=y=z$.  Can someone help me find an easier solution? I started with assume only two are equal, without loss of generality, $x=y$. Then we get $$1 + \dfrac{x}{z} + \dfrac{z}{x}$$ $$1 + \dfrac{x^2 + z^2}{xz} = 1+ \dfrac{(x-z)^2 + 2xz}{xz} = 1 + 2 + \dfrac{(x-z)^2}{xz} \ge 3$$ To prove the general result I considered using a derivative with respect to $y$ to show that, starting with $x=y$ and increasing $y$ by a tiny amount, will show the equation's derivative as positive. I haven't gotten this to work yet. Any ideas?


The power delivered by a force is given by the relation $$P=\frac{\alpha}{\beta}e^{-\beta t},$$ where $t$ is time. Find the dimensional formula for $\alpha$.   So, $-\beta t$ doesn't make sense for the dimensional formula of $P$. But then we have two unknowns and one equation since we do not know if $\beta$'s dimensions. But then if I put $\beta t$ as dimensionless, it fits just right with the answer $([ML^2 T^{-4}])$ . But does this happen exactly. Why is  $\beta t$ dimensionless, because we are just using it's numerical value. Please help. I don't understand it.

Take this equation  $$v^2 = 2 a \sin(2\pi b t)$$ where $v$ is a velocity and $t$ is a time. Find the dimensions of $a$ and $b$.   Finding the dimensions of $a$ is easy as the $\sin$ has no dimension  so it will have the same dimensions as $v^2$.  But the problem is finding the dimensions of $b$ because the $\sin$ takes an angle as a parameter, and angles have no dimension we can simply say that $b$ should be $1/[\mathrm{T}]$ which will make the entire argument dimensionless. But isn't that just wrong?   Because there are some physical laws that have $\sin(t)$ for example where $t$ is a time, so it isn't a condition that the angle's value should be dimensionless.  This is really confusing.


I'm trying to execute a shell script from Java.The script is supposed to download the file from the URL using wget.Here goes my code.       public class RunShellScriptFromJava {          public static void main(String a[]) {          try {               ProcessBuilder pb = new ProcessBuilder("/bin/sh","script.sh");               Process p = pb.start();               p.waitFor();               System.out.println("Success");          } catch (Exception e) {          e.printStackTrace();       }      }     }   Content of script.sh       echo "start"      wget http://alex.smola.org/drafts/thebook.pdf      echo "end"   My Question: Is this the right way doing it?If not please point me in the right direction.It doesn't throw any exception but I see that the file is not getting downloaded.Any lead/help is appreciated.  Thanks.  PS:I have given execute permission for the script

It is quite simple to run a Unix command from Java.   Runtime.getRuntime().exec(myCommand);   But is it possible to run a Unix shell script from Java code? If yes, would it be a good practice to run a shell script from within Java code?


I wanted to report a bug in the Android app here on MSE (as suggested by the help text) and got a warning "some of your questions have not been well received..."   As I only have asked two questions yet (both positive score) I wonder why.

When I came to post (about an unrelated SSL cert bug that turns out to be a duplicate), I saw a warning about a potential question ban on meta.SE.  I seem to have three questions on meta.SE, all with positive scores.  Why is this, and do I need to worry?  I am banned from asking questions on programmers.SE.


I saw some answers using a preseed file (that were said not to work because of a bug), but I'm interested in using the standard live image and not editing the preseed file there. If squid-deb-proxy is on another machine on the network, can I just install the client in the live system and install as normal, or is there something more to it?

Using Lucid, installing from the Lucid mini.iso.  Both AMD64.  In the following I've tried as \, all of apt-get, apt-install, anna-install, dpkg:  d-i preseed/early_command string <cmd+opt> squid-deb-proxy-client   I've also tried:   d-i preseed/early_command string /usr/bin/wget \     -O squid-deb-proxy-client_0.3.1_all.deb \     http://ubuntu.media.mit.edu/ubuntu//pool/universe/s/squid-deb-proxy/squid-deb-proxy-client_0.3.1_all.deb && dpkg -i squid-deb-proxy-client_0.3.1_all.deb   Is this possible, and if nor what is the earliest point one can get a installation to use the squid-deb-proxy server?


I know abelian groups have only 1D representations. Is the converse proposition true? i.e. If a finite group has only 1D irreducible representations, is it abelian?

Suppose $G$ is a group and that every irreducible representation of $G$ has dimension $1$. Why does this mean that $G$ is abelian?  The number of $1$-dimensional representations of $G$ is given by $|G/G'|$, where $G'$ is the derived subgroup of $G$. So if every irreducible representation of $G$ has degree $1$, then the number of conjugacy classes of $G$ is equal to $|G/G'|$. I can't see how to conclude that $G$ is abelian (or if this is the right approach).  Any help appreciated. Thanks


Let $(a_n)_{n \in \mathbb{N}}$ be a bounded sequence in $\mathbb{R}$. Denote by $L := \sup\{a_n : n \in \mathbb{N}\}$ the Supremum. Suppose that $L \notin \{a_n : n \in \mathbb{N}\}$. How can I show that $L$ is an accumulation point,i.e., I have to show hat there is a subsequence $(a_{n_{k}})_{k \in \mathbb{N}}$ of $(a_n)_{n \in \mathbb{N}}$ such that $$ \lim\limits_{k \to \infty} a_{n_{k}} = L. $$ In other words $$ \limsup\limits_{n \to \infty} a_n = \sup\{a_n : n \in \mathbb{N}\}. $$ My idea was to give a proof by contradiction. But this seems hopeless. First I have to show that for $\varepsilon > 0$ there exist a $m \in \mathbb{N}$ such that for all $k > m$ we have $$ |a_{n_{k}} - L| < \varepsilon. $$ This would show me that there exists an infinite set of terms of $(a_n)_{n \in \mathbb{N}}$ which satisfy $|a_n - L| < \varepsilon$. How can I prove this? Then I think it is not difficult to construct a subsequence which converges to $L$. I only need help for the first part.

It just seems like I can't wrap my head around this. For a set $A$ how can I show that the supremum of that set $\sup(A)$ is also a limit point of said set? Can I just set $$a=\sup(A)$$ $$b\le a \: \:  \forall \: b \in A$$ and then show that there's a point different from $a$ in any $\epsilon$-neighbourhood for any $\epsilon>0$? Or should I use a completely different approach?


In this sentence is "at school": Everyone at school knew he was the new kid on the block.  In this sentence is "in school": When I was in school I would go to the library day to day to study. Can you teach me about that difference.

I know that we use the preposition at to describe a place. I learned French at school is one of the examples I can think of.   I came across two examples that use the preposition 'in' with 'schools' in the context of 'learning'.   Example #1 from the  website:      Eleven things that you will never learn in school.   Example #2 from      Do you think the skills you learn in school will help you get the job you want?   The use that I had in my mind is here on      Should Parents Control What Kids Learn at School?


I saw on  today, viewing it through the Android app, that the question body, and answers body is missing.   This is the first time I saw this problem.

Note: the bug has returned in version 1.0.89 in a somewhat different form. See:      This possible bug report is similar to the bug in  that was deemed not-reproducible.  I can reproduce something similar with more recent app & Android versions.   App Version: 1.0.34 (original report; is still present in 1.0.38, 1.0.42, 1.0.58) Android Version: 4.4 (up to 4.4.4) Device: Motorola Droid Maxx   In the examples below, you can see some blank answer bodies.  These are on different sites, and represent answers with both edited and non-edited text. In the first example, I clicked on the top answer tab to get to the answers, and in the second example I clicked on the bottom "View n Answers" button. (Trying to be a good little tester!)  Because I've seen this blank-answer-body intermittently over the past couple weeks (before the May 7 update), my process to test was just to go to the first site I frequent and then systematically click through the question list until I found a question with answers in which at least one answer was blank.  For all three sites shown below, it was within the first 5 or 7 questions sorted by newest.  Please note that I have seen many questions with several answers, none of which were blank. It is truly intermittent.  Example blank answer body at Workplace.SE:    Example blank answer body at Programmers.SE:    Example blank answer body at UX.SE:    And now here's the kicker, which makes me think this is some sort of content-loading latency issue rather than a rendering issue:  I returned to the left-side menu, selected the User Experience site, picked the same question as above, and then clicked the top answer tab to view answers again, and lo and behold the text is there:    I then went back to the other questions with blank answers, shown above, and the answer bodies were no longer blank.  I am happy to go through more tests/paths and do screenshots if it is helpful.  The same bug also appears in question bodies.


What can it be the reason to get NullPointerException sometimes with below code piece.    Exception in thread "main" java.lang.NullPointerException      [java]  at java.io.Reader.<init>(Reader.java:78)      [java]  at java.io.InputStreamReader.<init>(InputStreamReader.java:72)      [java]  at helloworld.HelloWorld.fixture(Unknown Source)      [java]  at helloworld.HelloWorld.replaceScheduler(Unknown Source)      [java]  at helloworld.HelloWorld.test(Unknown Source)      [java]  at helloworld.HelloWorld.main(Unknown Source)     My code i trying to read that file extension .fscript ; the problem is getResourceAsStream(name) is returning null  Here is all code:    public class HelloWorld {     FScriptInterpreter fscript;     Node rootNode;           private Reader fixture(String name) {         InputStream stream = HelloWorld.class.getClassLoader().getResourceAsStream(name);         return new InputStreamReader(stream);     }        private Component getChildByName(Component parent, String name)             throws NoSuchInterfaceException {         ContentController cc = Fractal.getContentController(parent);         for (Component child : cc.getFcSubComponents()) {             if (name.equals(Fractal.getNameController(child).getFcName())) {                 return child;             }         }         return null;     }    public void replaceScheduler(Component root) throws Exception {         Component client = getChildByName(root, "client");         fscript.loadDefinitions(fixture("replace-scheduler.fscript"));         fscript.apply("replace-scheduler", new Object[] { rootNode });         Component newScheduler = getChildByName(client, "client1");         assertNotNull("New scheduler not found.", newScheduler);     }     public void test() throws Exception {       Factory factory = FactoryFactory.getFactory(FactoryFactory.FRACTAL_BACKEND);          Component root = (Component) factory.newComponent("helloworld.ClientServerImpl",new HashMap());          Fractal.getLifeCycleController(root).startFc();          ((java.lang.Runnable)root.getFcInterface("r")).run();          replaceScheduler(root);      }           public static void main(String[] args) throws Exception {            HelloWorld h=new HelloWorld();      h.test();     } }

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?


has been migrated on . When I noticed it, I created an account on that site, and my answer was associated with my account, but the comments I posted before the migration have not been associated with my account.    The comments should be associated with the account, after I create one on the site where the question has been migrated. I could have made comments that were pertinent on the previous site, and I could like to remove them; sometimes, I could just delete the old comment, and add a new comment that is more pertinent for the site where the question has been migrated.

Background: when question is migrated from site A to site B and the author doesn't have account in site B, their name will appear "gray" until they log in to site B and associate the accounts, then the avatar show and all is good. No problems here, same for answers and their authors. Problem: if user from site A posted comments while the question was still in site A, their name will stay gray and unclickable even after they logs in and have account in site B:  , but most likely it's global problem, not specific to that one occurrence.


Axiom of regularity:  Every non-empty set x contains a member y such that x and y are disjoint sets. \begin{align*} \forall x (x\ne \phi \Rightarrow \exists y \epsilon x (y \cap x = \phi)) \end{align*}  As I have taken the set as a subset of natural numbers, and they are not Sets themselves. i.e 1 is not a set. As all the elements of A are not sets, how can we show the above axiom is satisfied?  we can't show  $1 \cap A = \phi$, as 1 is a number and A is a set. incompatibility of the operation $\cap$. (if I am not wrong.)

I cannot understand the axiom of regularity. It says that any generic non-empty set $A$ contains an element $X$ such that $ X\cap A = \emptyset $. How can this be true? If, for example I have a set $A = \{1,2,3\}$, according to this axiom there must be an element inside of this set such that its intersection with $A$ is the empty set, but $1,2,3$ are part of $A$, how can the intersection be an empty set?


i have a 5 bit binary number and now i want to display the 5 bit number on seven segment display i have 20 digital inputs and i have added them using full adder the output result is a five bit bonary number and now i want to display them on two digit seven segment display guide me in the most easiest way i have tried using logic gates but the connections take very long time and also there is complexity

I'm having trouble displaying a binary number into a display. I'm not sure of how to split a number in binary into its individual numbers.  For example, if I want to display 25, I want to split this into "2" and "5" in binary.  I have 8 bits coming in and would like to split it into two 4 bit parts with the first 4 bits representing the first digit in binary and second 4 bits representing the second digit in binary.   EDIT: To clarify, I'm trying to do this using logic gates.


Is it possible to put on trace or  get log of all activity on android device. If so, How?Also are there any key logger application

There is a lot of interesting stuff in the Android system log, that is helpful in many ways   find root causes of problems identify misbehaving apps   How can I view and examine the Android log?


So, I just wrote down the following sentence.   'Now my attempt is to understand the cause of such behaviour. Is it the childhood experiences, as we find in the movie?'  I'm not sure if I've got the punctuation correct in the last sentence with the use of question mark. If reading out, you'd expect the speaker to take a pause after 'experiences' and then provide more information. However, 'as we find in the movie' isn't really an interrogative so putting the question market after it seems erroneous. Kindly suggest the correct punctuation.

Is this the correct use of the question mark?  Should it be at the end outside of the closing bracket?  See example below     How do we deliver it? (to the learner)


When I tried to add color to the cells to differentiate concavity points up from down, the text in the cells moved down versus the cells with no color added. What can I do to keep all cells text at the same level?  \documentclass[12pt,table]{report} \usepackage{xcolor} \usepackage{mathtools}  \usepackage{longtable,tabu}  \setlength{\extrarowheight}{4pt}  \begin{document}  \bigbreak \begin{longtabu}{ |p{\dimexpr.25\linewidth-2\tabcolsep-1.3333\arrayrulewidth} |p{\dimexpr.15\linewidth-2\tabcolsep-1.3333\arrayrulewidth} |p{\dimexpr.25\linewidth-2\tabcolsep-1.3333\arrayrulewidth} |} %\textwidth \hline \centering \boldmath $\text{Lable on Sketch}$ & \centering \boldmath  $x$ & \centering \textbf{Concavity} \tabularnewline\hline  \centering $x_{0}$ & \centering $0$ & \centering \color{red}Concave up\\\hline   \centering $x_{0}$ & \centering $0$ & \centering Concave up\\\hline  \end{longtabu}  \end{document}

The following code shows that a \color{red} command increases the height of a tabular cell. I want to use a switch, not a command as \textcolor{red}{text}.  \documentclass{article}  \usepackage{xcolor} \usepackage{float}  \begin{document}  \begin{table}[H] \begin{tabular}{*{2}{p{0.45\textwidth}}} \hline \color{red} header & header \tabularnewline \hline  %  content  & content \tabularnewline  content  & content \tabularnewline  content  & content \tabularnewline \hline \end{tabular} \end{table}  \end{document}     How can I work around this problem?


As can be seen in , the site  is closed until further notice (which can take long weeks/months) hence all the links pointing to it are dead.  I would like to suggest removing the dead links from the election results page in Stack Exchange sites, e.g. on :        The link More Information about the candidates points to the URL  which returns a 404.

I can't connect to  or  — the initial connection times out every time. I check this every week, and it worked fine last time, so it must be something pretty recent. (Further HTTPS deployment?)


Each of the tasks from the Patient Task panel illustrated previously is shown on the Tasks tab of the Visit.  Each of the tasks from the Patient Task panel illustrated previously are shown on the Tasks tab of the Visit.  Which is correct?

A source says that the word "each" should always be followed by a singular noun, but however I look at it in this sentence it just doesn't seem to fit:     foo [comprises] multiple binary programs that each performs a single task.   Should it be "performs" or "perform"?


What I have: $A \in \mathbb{R}^{n \times n}$ is a symmetric positive-definite matrix and has Singular Value Decomposition $A = U\Sigma V^T$.  What I want: prove that $U = V$.  Also... does $A$ has to be positive-definite for this to be true?  Edit: There is the exactly same question , but none of the answers there satisfy my doubts. I'm talking in comments with people here and there. If I come up with a detailed enough answer I might write it there. But I suggest also reading the comments on my question here, they are helpful.

Consider the SVD of matrix $A$:  $$A = U \Sigma V^\top$$  If $A$ is a symmetric, positive semidefinite real matrix, is there a guarantee that $U = V$?  Second question (out of curiosity): what is the minimum necessary condition for  $U = V$?


I’ve just got Ubuntu 14.04. I changed from Google Chrome (I have a Chromebook) and I’m finding it hard installing NFS world. It says I have unmet dependencies and so forth. I tried getting Wine but that was unsuccessful as well...  user@chrubuntu:~$ sudo apt-get install wine Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  wine : Depends: wine1.6 but it is not going to be installed or                  wine1.7 but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I tried to update and upgrade when I updated it this is what appeared:  (it runs a few stuff in between)  Reading package lists... Done W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages) W: You may want to run apt-get update to correct these problems   Why is it saying that when I just ran the update?  user@chrubuntu:~$ sudo apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following package was automatically installed and is no longer required:   kde-l10n-engb Use 'apt-get autoremove' to remove it. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   I need some help. I only changed to this so I could play NFS world.

After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


Find all $n,k \in \Bbb N^+$ such that $(n-1)!=n^k-1$  Using $n^k-1=(n-1)(1+n^2+...+n^{k-1})$ and cancelling $(n-1)$ in each side, we get that $$(n-2)!|1+n^2+...+n^{k-1}$$ So, let's suppose $n$ is an even number, in $(1+n^2+...+n^{k-1})$ we have $k$ terms, where $k-1$ are even ($n^i$ for $i>0$) and one is odd ($1$), so we have that $1+n^2+...+n^{k-1}$ is odd. Also, if $n$ is even, then $n-2$ has the same parity so n-2 is even; therefore, if $n-2>0$ then $(n-2)!$ is even and that is a contradiction. So with this, when n is an even number, the only solution is $n=2, k=1$ Now, in every other solution, $n$ is odd.  Let's suppose $k=1$. we have $(n-2)!=1$ (for $n, n-2$ odd) and it follows $n=3, k=1$.    Using this, if $n$ is odd, then $n^x$ is odd too, so it follows that we have $k$ odd terms, so if $k$ is even, then $(1+n^2+...+n^{k-1})$ is even, since every pair of terms sums an even number. From $n=4$ onwards, $(n-2)!$ is even so k has to be even too.   Let's suppose $k=2$. Then $$(n-2)!|n^2+1$$ $n=5$ works and let's prove is the only solution. Supose there is a $n=5+m$ for $m>0$. So: $$(m+3)!|m+6$$ And it's not hard to prove that $(m+3)!>m+6$ if $m$ is not $0$  So I got stuck here, I could only find these 3 solutions, and I don't know how to prove that there aren't more, since, for more bigger values it seems that $(n-2)!$ is greater if $k<n-1$. Would appreciate any help on the proof, or hints. thanks.

How to find all positive integers $n$ such that $(n-1)!+1$ can be written as $n^k$ for some positive integer $k$?


For example, I have windows of my browser open, I want one to be open in one workspace and one in another. In the dock it shows multiple windows open, and when I click it it switches me to the other workspace where the other window is. Is there any way I can prevent it switching workspaces like this, and just show the windows open in my current workspace?

I would like my Dock to show only the windows of the current workspace. Especially in the little preview window. I find it very confusing to jump around workspaces when trying to find the right window.


I would need a hint to prove the following statement :  For every $\epsilon>0$ there exists $C_{\epsilon}>0$ such that for every couple $a,b\ge 0$ we have  $(a+b)^p\leq(1+\epsilon)a^p+C_{\epsilon}b^p$

In , the following theorem is used implicitly (see Example (a) on page 488):     Let $0<p<\infty$. For every $\epsilon > 0$, there exists some $C_{\epsilon} > 0$ such that $\forall a,b \in \mathbb{C}$:   $$ \left||a+b|^p - |a|^p \right| \leq \epsilon |a|^p + C_{\epsilon} |b|^p $$   Is this a well-known result? I would like to know its proof, and its name if it has one. Can someone point me towards a reference to this result which includes a proof, or give me a proof outline?  I've tried using Jensen's Inequality for the case $p>1, a,b>0$, but it doesn't seem to work out.


In medicine, the sign 'R/' or 'Rx' is often used to denote prescription or treatment.  I use it a lot when taking notes in class and I'd like to use it in my LaTeX documents, too. The problem is that it's hard to find out how to write this in LaTeX, because searches like 'latex medicine' or 'latex prescription' will be overflooded by pages about latex allergies.  How can I write this sign in LaTeX?

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


I want to do a really simple thing: add OpenLayers/Google Maps basemap as WMS layers. I found this answer:    I installed the OpenLayers plugin, restarted QGIS, but under "Plugins" dropdown there is no OpenLayers plugin. Is it a bug? Or I need to do also some other things to add plugin? Or where else I can find this plugin settings?  Probably my question is: how to add world basemap layer to QGIS?

Although I have installed the OpenLayers plugin in QGIS 2.4, I cannot see it in the list when I click on Plugins.    Does anyone else have this issue?


I found a problem:  How can I solve this error?

I get this error message, during compiling my .tex-document.  line 234 - ! Package inputenc Error: Unicode char ́ (U+301)(inputenc) not set up for use with LaTeX.See the inputenc package documentation for explanation.Type H <return> for immediate help.... \cleardoublepage   I am writing my thesis right now and I am very confused about this error message, since it seems to be connected to a special character, which I do not use in my manuscript. The solution up to now was the reloading of an older version of my manuscript...after some hours of work and after several times of successful compiling this error suddenly occurs again. I don't get it why, since I just write some text, add some figures and nothing more...  any suggestions, how I can solve that issue? I have no idea, what kind of MWE I should post here :( where does this comment "line234" refer to. Line 234 is normal text in my manuscript...