What is the size of a boolean variable in Java?

Can any one tell the bit size of boolean in Java?


Discourage questions being marked as answered within an hour or so of being posted

I keep on seeing a fair number of questions (such as ) which get marked as answered within 5-10 minutes of being posted. Sometimes the questions like this are insanely popular and actually see some proper discussion, however often I see questions have few views and only 1 answer. The trouble with these questions is that very few people have scrutinised the answer for correctness, or possibly a better solution. I always make a point of not accepting my answers until a day or so has passed — would it not be a good idea to put a short (1 hour or so) time limit on accepting answers on new questions with few views or votes, or perhaps just an additional confirmation dialog, something along the lines of:  Your question is new and not many people have had a chance to look at it yet.  Are you sure you don't want to wait to see if anyone else has a better suggestion?


Minor Illusion can be up to a 5 cu ft in dimension as described in the spell. Any thing that touches the Illusion goes through it like it would a hologram then, right? Can you then hide inside the 5 cu ft dimension the Illusion occupies? While not truly invisible can one at the least get advantage to Stealth from it?  In the same vein, can you then cast Minor Illusion on yourself to make yourself look like a part of the environment to get an advantage on Stealth?  I had an idea for a Ninja/Sorcerer to Quicken cast Prestidigitation (flash/smoke bomb) and Minor Illusion together a la "Ninja Vanish" and to look like I've disappeared but still be there waiting for them to leave thinking I gave them the slip. Yes Misty Step can technically do that but I want to save that as a panic button to save myself from a potential early religious or infernal experience.


How to individually select  and then use modulus to select the odd ones

ALright so I got a homework from my teacher to first select every individual
 and then use modulus to select only the odd ones and change their color. And I have to say that I am completely stumped.  I have tried selecting using child nodes: var listaOne = document.getElementById ("lista1").childNodes[0];  HTML

List item 1

List item 2

List item 3

List item 4

List item 5

   JS      listaOne = document.getElementById ("lista1").childNodes[0]; listaTwo = document.getElementById ("lista1").childNodes[1]; listaThree = document.getElementById ("lista1").childNodes[2]; listaFour = document.getElementById ("lista1").childNodes[3]; listaFive = document.getElementById ("lista1").childNodes[4];   I want to be able to choose an
 individually


What would happen if ZFC were found to be inconsistent?

If, one fine day, someone found a contradiction in ZFC (or even ZF), what implications would such an event have for mathematicians? Is there currently any backup axiomatic system on par with ZFC that would enable mathematicians to continue pursuing mathematics, should the unthinkable occur?


Bash Query: how to append string variable to end of a specific line dictated by a int variable?

This is the code for appending string to a specific line number: sed -e '1s/$/has/' -i testapend.txt  However, how would you be able to do the same thing but using a variable for the string and for the line number (int)? I have so far tried inserting $variable into the slashes and chucking in braces, but it either says unknown command or extra characters after the command.


Linearly independent elements are less than generators in a module.

Let $R$ be a commutative ring and $M$ a finitely generated $R$-module. Let $s$ be the maximum number of linearly independent elements of $M$, while $t$ is the minimum number of a system of generators of $M$. Show that $s\leq t$.  It is immediate in the case of vector spaces, but my first attempt (explicit computation) didn't work here due to the fact that there are coefficients (elements of $R$) without an inverse. I tried in so much other ways spending a lot of time, and I should be very glad if you cold give me a precise, complete and rigorous proof. Thank you in advance.


I am an physics undergrad in my pre-final year. Recently, I tried learning some QFT (from the likes of Peskin and Schroeder’s 1st 4 chapters, David tong etc.) and got interested in it’s working in a condensed matter setting. As it happens, listening to broad applications of QFT in CMP got me interested in learning about Keldysh field theory and am curious to see how it handles non-eqm situations. Currently I am stuck about charting a  proper path/topics list that can help me reach Keldysh field theory in a proper manner. The only resource I have seen as such are ArviX articles which are quite inaccessible for me.  So I am asking about the necessary topics/chapters required to learn Keldysh Field theory. I’ve done some path integrals and am starting to know about imaginary time calculations. But I’ve no idea how exactly to proceed (another answer on  regd the resources is quite useful, but that assumes some pre-requisite, I wanted if a broad list of topics could be highlighted to reach there). Any resources/specific topics would be highly welcome.  As per my background - I have taken course work in Quantum mechanics (scattering/perturbation and relativistic) and am currently taking a course in solid state physics and stat mech. Ig some understanding of material here (i.e. coursework) would be pre-requisite, but till now following Negele and Orland’s book for the 1st couple of chapters, I’ve managed to build up whatever I need on the go. Hoping for suggestions!


How can I concatenate an int to a string?

I have done a good hour or so of research, but I can't find a method that works for me that I actually understand, as I don't understand how buffers work. I've tried the to_string method, I've tried the .append() method, and obviously, a simple concatenation method.  My code:   fileLog[fileLogIndex].append(playerTurn+":"+moveColumn);  //fileLog[fileLogIndex] += playerTurn && ":" && moveColumn && ", ";   So. The purpose of this, or my idea, was to keep track of each move in a connect 4 game I wrote today. This was supposed to append each move, in the format aforementioned. PlayerTurn is stored as an int, 1 being player 1, 2 being player 2, and the moveColumn variable is the column that the user selected to drop their piece. If player 1 dropped a piece into column 4, the idea was to append "1:4, " to the variable and then write that line to a file.  As you can see, I have tried a few methods, like append, and even though you can't see, I have tried to to_string () method, but I either get an error, or "1:1" gives me a smiley face in the dos window, or a null in notepad++ when opening the file.  I don't want to use a method I don't understand, so I apologize if this is a repeat of another thread, I'm just tired of staring at this 1 line of code and getting nowhere with the methods I am trying. If I have to use a buffer to do this, fine, but can someone explain to me, in somewhat newbie terms, what each line is doing?   For the record, I am using Visual Studio 2010, and I'm 90% sure I don't have C++11, which I read somewhere is the reason to_string isn't working as expected for me..


I have edited my profile at Stack Overflow many times. The edit form always reports as successful,  but my name at Stack Overflow is still  despite all my tries.


Implication as defined in mathematical logic

If we can take the truth of an implication to mean the validity of reasoning, then that would mean that all reasoning that begins with false premises is valid reasoning. Are there no counterexamples to this, how is this justified and why does it work in mathematics ? It is intuitively clear that if we start with true premises, and conduct valid reasoning, we must come at true conclusions.  And we can easily come up with examples where we start off with false premises, conduct valid reasoning and come at true conclusions (or false ones) for instance 3=5,              5=3 +              8=8 and so on. Does it even make sense to talk about valid/invalid reasoning when we start off with false premises ? What were the reasons and justifications for defining implication (its truth table) as we know it today, what's the historical background of it ?


Allow duplicate permalink slugs for posts in different categories

I have my permalink format set to /%category%/%postname%/ and I have two posts with the same permalink slug, but in different categories.  Ideally, the two permalinks should look like this:  http://example.com/category-1/post-title/ http://example.com/category-2/post-title/   But when I publish the second post, then its slug is changed to post-title-2, which makes the resulting URL http://example.com/category-2/post-title-2/.  How can I use the same slug for multiple posts that are in different categories?  suggests using an outdated plugin that doesn't work anymore.


What is the difference between thermodynamics and statistical mechanics?


Can't access my phone memory suddenly after using SD card as internal memory

A few weeks ago I integrated my SD card to use as phone memory. Everything was fine until a couple of days ago.  All of a sudden I saw the "insert SD card" notice appear on the notification bar. I open the back cover but the SD card looked like it was in place. I remove it and insert it back and the notice disappears. But then I notice that when I go to file explorer (FX) to access my files, it says "Access was denied". I can't access anything that is on my phone memory, although the apps are working. I guess system files are OK, but everything else is not.  My phone is rooted so I tried to access the files through TWRP but I can only see system folders.  Phone is a Moto C plus. Nougat.


For example, let $p = 3$ and $q= 11$, choose $e = 3$. What computation I have to apply in order to find the corresponding $d$? I know it's 7, but I want to know the exact process to be applied to find it.


How do the tenses and aspects in English correspond temporally to one another?

Non-native speakers often get confused about what the various tenses  and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter.  I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be  incorporated into the diagram.    Nota bene: What this is not is a discussion of whether there are  more than two tenses in English. , to which this question is not intended to supply arguments one way or the other.  Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better.  Breaking News There is now an excellent ELU blog article titled  . It is highly recommended reading.


How to create this curved 90-degree-angle quickly

I want to make this:    from this:    I created the beveled edge by beveling on the cube, then beveling the inner edge, however that resulted in a weird diamond shape:    So I ended up disolving edges and fighting with the uncooperative knife tool for the next 2 minutes or so, just to get a clean bevelled edge like I wanted. How to do it faster, without the hassle?


Messaging.InboundEmailHandler email test class not covering whole class

Please help cover bold lines dont know why email.plainTextBody.length() >=255 is not covering if(email.plainTextBody!=null && email.plainTextBody.length() >=255) { bodyString= email.plainTextBody.split('\n', 0); body = bodyString[0]; comment = bodyString[1];  uName = bodyString[2]; uString = uName.replaceAll(regex, ''); uniqueContractNo = uString.replaceAll( '\s+', ''); global class frEmailServiceClass implements Messaging.InboundEmailHandler {     global Messaging.InboundEmailResult handleInboundEmail(Messaging.InboundEmail email, Messaging.InboundEnvelope envelope) {     string body='', fromEmailId='';         list<string> approvalString = new list<string>{'APPROVE', 'APPROVED', 'YES'};         list<string> rejectionString = new list<string>{'REJECT', 'REJECTED', 'NO'};         string[] bodyString;         string comment;         string uniqueContractNo;         string subj =email.subject;         string regex = '[a-zA-Z]{1,}|\\:';         string cString = subj.replaceAll(regex, '');         string cName = cString.replaceAll( '\\s+', '');         string uName;         string uString;         try{         **if(email.plainTextBody!=null && email.plainTextBody.length() >=255) {           bodyString= email.plainTextBody.split('\n', 0);         body = bodyString[0]; comment = bodyString[1];  uName = bodyString[2];         uString = uName.replaceAll(regex, ''); uniqueContractNo = uString.replaceAll( '\\s+', '');**                                                                                }                 fromEmailId = email.fromAddress;            Contract_management__c   contractQuery = new Contract_management__c();             if(cName!=null){             system.debug(cName);         contractQuery = [select id,name,Status__c,Comments__c,Unique_Contract_Number__c,owner.email,Legal_Person_Email__c,Send_Email_To_Legal__c from Contract_management__c where name=:cName and Legal_Person_Email__c=:fromEmailId limit 1];             }                  **for(string a:approvalString){                     if(body.contains(a) && contractQuery!=null){ contractQuery.Status__c= 'Legal Approved';             contractQuery.Send_Email_To_Legal__c=false;  contractQuery.Comments__c=comment;             contractQuery.Unique_Contract_Number__c=uniqueContractNo;             }                            }                  for(string r:rejectionString){         if(body.contains(r) && contractQuery!=null){ contractQuery.Status__c= 'Legal Rejected';             contractQuery.Send_Email_To_Legal__c=false; contractQuery.Comments__c=comment;               contractQuery.Unique_Contract_Number__c=uniqueContractNo;             }                            }                           update contractQuery;**         }         catch(Exception ex){             System.debug('Line No: '+ex.getLineNumber()+' Message: '+ex.getMessage()+' Cause: '+ex.getCause());         }         Messaging.InboundEmailResult result = new Messaging.InboundEmailresult();             return result;     } }  Test class method @isTest      static void testContractEmailServiceMethod(){         string cid;         Contract_management__c queryC = [select id,name,Legal_Person_Email__c,Customer_Account__c,Contact__c,Contract_Type__c,Contract_Start_Date__c,Contract_End_Date__c,Status__c from Contract_management__c limit 1 ];         cid=queryC.name;     list<string> approvalString = new list<string>();     Messaging.InboundEmail email = new Messaging.InboundEmail() ;     Messaging.InboundEnvelope envelope = new Messaging.InboundEnvelope();          FREmailServiceClass contractClassObj = new FREmailServiceClass();          email.plainTextBody = 'APPROVED\n ok\n 0090';     email.fromAddress ='test@u.com';     email.subject = cid;               contractClassObj.handleInboundEmail(email, envelope); }


Can't find error in my SQL using named parameters

In PHP I'm building, at least trying to, a query using named parameters like so...  $answerNumber = "a1"; $questionNumber = "q2"; $answerText = "Test Answer";  //INSERT QUERY $sql = "INSERT INTO $questionNumber (:answerNumber) VALUES (:answerText)"; $stmt = $db->prepare($sql); $stmt->bindValue(':answerNumber', $answerNumber); $stmt->bindValue(':answerText', $answerText); $stmt->execute();  $errorInfo = $stmt->errorInfo();  if(isset($errorInfo[2])){     $error =    $errorInfo[2];     echo $error; } else {     echo "No errors."; };   But I keep getting an error thrown. The error returned...     You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''a1') VALUES ('Test Answer')' at line 1


Why are there so many bottomless pits in Star Wars

Possible Duplicate:          Nearly everywhere in the Star Wars universe there are bottomless pits. (I'm referring to the universe portrayed in the movies.) None of them have railings and people keep falling into them. You'd think they'd realize this is a bad design, but apparently not.     Why are there so many bottomless pits in the Star Wars universe?


Inﬁnite dimensional separable Hilbert space with orthonormal basis (weak convergence of $\frac{1}{N} \sum^{N^2}_{n=1} e_n$)

Let $H$ be an inﬁnite dimensional separable Hilbert space with orthonormal basis $(e_n)_n≥1$. Let $f_N = \frac{1}{N} \sum^{N^2}_{n=1} e_n$, $\forall N ≥ 1$.   I am trying to show that $e_n → 0$ weakly, as $n →∞$ and $f_N → 0$ weakly, as $N →∞$, while $ \|f_N\| = 1$, $\forall N ≥ 1$.


Book identification about boy who gets computer zapped into head

I remember this book from 15+ years ago about a normal boy who was working on his computer (replacing the motherboard maybe?) and he touched something and got zapped. When he came to he came to realize that the computer shocked itself into his head.   Cut to being the hero sometime down the line and maybe saving someone who was kidnapped? Or was kidnapped himself and had to get out of it using the computer?  I don't know why it's in my head all of the sudden but Google isn't helping me at all!


I know that you can't export blender models with their materials. Is there any way I may be able to turn the materials into a texture which I can export separately? Thanks, I'm quite new and I just need a solution to this problem.


How do I convert a git repository folder into a regular folder?

If I want to turn a local git repository into a regular (non versioned) folder what do I have to do?   I've had an SVN project before and in that case I had to delete an SVN folder from every directory. I've read git has one project folder but after some searching it sounds like there is more to it.   PS I do not want to export a repository because not all the contents are checked in.


I am stuck on whether to use 'frame' or 'frames' of reference. Example sentences: This study seeks to add value to the theologies of the Hebrew Scriptures in both its Hebrew and Greek frame/frames of reference. and ... exploring beliefs and ideologies when reference is made to the Divine in both its Hebrew and Greek conceptual frame/frames of reference.


Dual-boot. Windows 10 and Ubuntu 18.04 on different drives

I have a laptop Lenovo IdeaPad S340. Inside the laptop is the native NVME M.2 and I installed the SSD 2.5. I plan to use Windows for games, Ubuntu for work. I want to install Windows 10 and Ubuntu 18.04 LTS on different drives. When installing Ubuntu, I would like to encrypt the hard drive. I also want to hide a Windows disk from Ubuntu to avoid damaging the file system. My plan was to disable SSD 2.5 in BIOS and install Windows on NVME M.2. Then disable NVME M.2 and install Ubuntu on SSD 2.5. When I boot, I just select the drive I need. Perhaps for experienced users this seems primitive but it is ideal for me because of it simple.  But my Lenovo laptop has a limited BIOS with advanced settings disabled, so I cant manage SATA and PCIE configurations. I called Lenovo support and they refused to help me unlock the BIOS.  So here is what I have:   The BIOS says that plugged SSD 2.5 in SATA port 1, NVME M.2 in PCIE. The Windows USB installer defines SSD 2.5 as drive 0, NVME M.2 as drive 1 The Ubuntu USB installer defines NVME M.2 as /dev/nvme0n1, SSD 2.5 as SCSI2 (0,0,0) (sda) - /dev/sda.   Default settings in the BIOS:   Boot Mode - Legasy Support Boot Priority - UEFI FIRST Fast Boot - Enabled Secure Boot - Disabled (Unactive, grayout. It only becomes active if select Boot Mode - UEFI.)   To be honest, I'm confused.    What BIOS settings should I use? Which operating system should I install first and on which drive? I ask this because Windows installer define SSD 2.5 as the first disk, and Linux installer define NVME M.2 as the first disk.   Please help me find the best solution.  UPDATE:  I decided to install only Windows. Without Linux. This is too hard for me. Thanks to all.


How one can input a small keyboard or any figure in text?


"File ended while scanning use of \FancyVerbGetLine"

The following LaTeX manuscript  \documentclass{article} \usepackage{xparse,minted} \NewDocumentEnvironment{MyMinted}{}   {\begin{minted}[escapeinside=||,mathescape=true]{c}}   {\end{minted}} \begin{document} \begin{MyMinted}    double diff(double (*f)(double), double |$x_0$|) {       return |$\frac{d(*f)}{dx}(x_0)$|;   } \end{MyMinted} \end{document}   produces (upon compilation with pdflatex -shell-escape) the following error message:  Runaway argument? ! File ended while scanning use of \FancyVerbGetLine. <inserted text>                  \par   What's the problem, and how can I fix it?


On dual boot system, Is it possible to use VirtualBox to boot other installed OS?

I currently run Windows 7 from a 256GB SSD as my Operating System.  Lately, for school, I've been using openSUSE linux inside a VirtualBox PC and I'm really liking it.  I'm starting to hate even working in Windows.  But I can't just abandon Windows.    I've been considering dual booting openSUSE and will likely purchase another SSD for openSUSE.     Once I have the dual boot set-up, there is going to be times I need to do something quick in the operating system that I'm not currently in. It would be a pain to have to reboot the computer each time I need to switch the OS for a simple task, especially from Windows since it doesn't let you save it's state.    From openSUSE, I want to be able to start a VirtualBox Machine using my Windows Drive.  And in Windows, I want to be able to start a VirtualBox Machine of my openSUSE Drive.  Would this be possible?    The issue I'm worried about is drivers.  For instance, the OS will be installed on native hardware and have the native hardware's drivers configured.  When I try to boot the OS in a VirtualMachine,  I feel like the OS is not going to know what to do, and have to reconfigure itself or just not work.    About a year ago an old WinXP DELL computer's hardware failed.  I was able to turn the HD into a virtual disk and have the WinXP system live on inside VirtualBox.  I remember that it was a challenge to get booted.


How do I invert the color ramp in QGIS?  I am using RdYlGn, but I would rather use GnYlRd.  Seems really easy, but I can't seem to find where the invert is.  I am using 1.8.0 on Windows 7.


Prove that a finite abelian group is simple if and only if its order is prime.

So I'm having trouble with this problem. I know that the definition of a simple group means that the group has no nontrivial subgroups. I know that this can be proven somehow with the help of the converse of Lagrange's Theorem for Abelian groups: If G is abelian of order n, and d is a divisor of n, then G has a subgroup of order d.   My attempt: (=>)Assume that G is a finite abelian group and is simple, then G has no nontrivial normal  subgroups.  (Now I don't know how to show that this implies that G has order p, where p is prime.  (<=)Assume that G is a finite abelian group with order p, where p is a prime. (Since the order of p is prime then what does this mean?)  Edit: Can someone check my new attempt at the proof?   (=>) Suppose G is a simple finite abelian group. Suppose for the sake of contradiction that G does not have prime order, then |G|=p*k where p is a prime number and k is an integer such that k>1. Then G has an element of order p. Let the element of order p be called x. Then , the subgroup generated by x, is of order p and  is not all of G. Since G is abelian, this subgroup is normal, which leads us to a contradiction. Therefore, G must have prime order.   (<=) Suppose that G is a finite abelian group and it’s order is p, a prime. Since G has prime order, then the only two subgroups of G are the trivial subgroup and the group G. Then, by definition the group G is simple since there are no nontrivial proper subgroups, and thus no nontrivial normal subgroups.


Third-party js lib (jQuery + DataTable) not being loaded in LWC

I was trying to create a new LWC importing a third-party library that we already used in the past with VF but within a LWC. We decided to use this one instead of lightning-datatable because we need a real-time filtering feature.  Following the LoadScript documentation, we imported both jQuery and DataTable libraries to Static Resources but when running the component we always get a "this.template.querySelector(...).DataTable is not a function"  Find hereby the html and js file of our component:  filteredTable.html  <template>     <lightning-card title="OST Events">         <lightning-layout>             <lightning-layout-item>

                                 Column 1	                                 Column 2

                                 Row 1 Data 1	                                 Row 1 Data 2

                                 Row 2 Data 1	                                 Row 2 Data 2

                 <template if:true={error}>                     <c-error-panel errors={error}></c-error-panel>                 </template>             </lightning-layout-item>         </lightning-layout>     </lightning-card> </template>   filteredTable.js:  import { LightningElement, track } from 'lwc'; import { loadScript, loadStyle } from 'lightning/platformResourceLoader'; import DATATABLE from '@salesforce/resourceUrl/dataTablesv10_18'; import JQUERY from '@salesforce/resourceUrl/jQuery'; import { ShowToastEvent } from 'lightning/platformShowToastEvent';  export default class FilteredTable extends LightningElement {     DataTable;     @track error;     @track dataExample;     @track successMessage = '';      dataTablejsInitialized = false;      renderedCallback() {         if (this.dataTablejsInitialized) {             return;         }         this.dataTablejsInitialized = true;         loadScript(this,JQUERY)         .then(()=>{             Promise.all([             loadScript(this, DATATABLE+'/DataTables-1.10.18/js/jquery.dataTables.min.js'),             loadStyle(this, DATATABLE+'/DataTables-1.10.18/css/jquery.dataTables.min.css')             ])             .then(()=>{                 this.showSuccessMessage();             })             .catch(error => {                 this.error = error;                 this.dispatchEvent(                     new ShowToastEvent({                         title: 'Error loading DataTables',                         message: error.message,                         variant: 'error'                     })                 );             });         })         .catch(error => {             this.error = error;             this.dispatchEvent(                 new ShowToastEvent({                     title: 'Error loading DataTables',                     message: error.message,                     variant: 'error'                 })             );         });       }      showSuccessMessage() {         // eslint-disable-next-line no-undef         this.template.querySelector('.example').DataTable();     }  }   I followed the library documentation hereby:   Thanks! edit: Deleted a test line with the standard jQuery selector that I tested and corrected the selector to only match .example class.


What if we modify the experiment such that both twins have a spaceship and they both do exactly the same thing on time they agreed up front? They accelerate for 1 day the opposite direction. Then they stop accelerating and drift away from each other for 10 years (in their local time) near c. Then they simultaneously decelerate and do the same thing in reverse: accelerate backwards, drift towards each other for some years then at the same time (by their pre-agreed timing) decelerate to meet again in the middle. If they execute the above in a perfectly symmetrical manner then the acceleration phases will be identical for both of them and they should age the same way during accelerations so we can concentrate on the non-accelerating phases of their journey. And then the twin paradox is back again. From each others frame the other will be younger but they will meet in the end... What is the resolution of this modified paradox?


How was Leo Bonhart from "The Witcher" able to kill three Witchers?

How was possible that Leo Bonhart, an "ordinary" human, was able to kill three Witchers? Was he just well trained, or had magic to help him as well?


Combinatorics and statistics question regarding drawing every element

Assuming a set of size X, on average how many attempts would it take to randomly draw every element in the set (returning it back after drawing)?  I have a hard time formulating a title for this question so if anyone can do it after reading my question I would be thankful.


I have been doing so many sudo apt-get update/(dist-)upgrade since yesterday and  something happend - so that I am confused now whether I am using still beta or the stable version.   How do I figure that out?


In Harry Potter, we only know 2 children of Aurors, namely Harry and Neville. We know that Harry borders on obscenely rich, is there any evidence that Neville is similar? Or is Harry's fortune, to some extent, a family fortune?  Basically, how much money do Aurors actually earn?


R, given a set of center points how to define the cell area?

I have the coordinates for the police stations in a city, they are grouped close together at the center and sparse towards the suburbs.  Since I do not have the shapefile for the jurisdiction of each station, I want to do a rough estimate of the area by defining non overlapping variable size and dimension polygons with the police station as the center.  Is there a standard function in R or any other open source toolkit which will do this?  If a standard function is not available what algorithms is best suited for this task?


Determine remote client IP address for Java RMI call

When I implement an RMI server (implement an interface that extends java.rmi.Remote) is there a way to get information about the current RMI request context, specifically the remote client's IP address?  public void myMethod() throws RemoteException {      log.info("remote IP is "+ RMISomething.getSomething());  }


How to build a .deb file from apt-get packages?

I'm in need of deploying the same software over and over on multiple systems.  How can I build a .deb file from apt-get packages like ia32-libs in Ubuntu so I don't have to download this software on each and every system?  (and wait while doing so and consuming bandwidth?)


Use the Mean Value Theorem to prove that there exists a $c\in(0,1)$ such that $f(c) = f'(c)$

Suppose that $f:[0,1]\to\Bbb{R}$,  $f$ is continuous on $[0,1]$ and is differentiable on $(0,1)$. Furthermore, $f(0)=f(1)=0$.   Prove that there exists a $c\in(0,1)$ such that $f(c)=f'(c)$.    The only hint I am given is to use the Mean Value Theorem on $g:[0,1]\to\Bbb{R}$ where it is defined $\forall{x}\in[0,1]:g(x)=e^{-x}f(x)$  I am genuinely confused as to what the question is trying to ask me. Would trying to solve this lead me to a proof similar to Rolle's Theorem? Any help is appreciated!


I would like to use a single pin (tri-state buffer, 3.3V logic in case this matters) to drive two P-channel MOSFETs as high-side switches. Only one of them will be 'on' at any time. When the pin is in the high-impedance state (hi-Z), I would like both turned off.   The solution I came up with is to pull-up the hi-Z state (to 0.2*Vcc, see comments) and use two comparators (open collector type) to drive the FETs when the pin is in either the Lo or High state:         – Schematic created using   I wonder: is there a better, easier or more elegant approach to this? Is this solution suitable for fast switching?


Is it allowed to explicitly ask for upvotes in the body of a post?

← Vote up if you think this post is helpful.   That's an example. I often see such requests in comments, but not sure if it's suitable in post body.


Does every continuous map from $\mathbb{Q}$ to $\mathbb{Q}$ extends continuously as a map from $\mathbb{R}$ to $\mathbb{R}$?

Given a continuous function $f:\mathbb{Q}\to\mathbb{Q}$ ,does there exist a continuous function  $g:\mathbb{R}\to\mathbb{R}$ such that   $g|_{\Bbb Q} = f$?  What I have no Idea about how to attempt this Question! Any suggestion will be very helpful.


query that groups cell data based on attribute

What would I need to look into form making a query on a table that looks like this:  +---+---+---+ | A | B | C | +---+---+---+ | 1 | x | 2 | +---+---+---+ | 1 | x | 3 | +---+---+---+ | 1 | x | 4 | +---+---+---+ | 2 | y | 5 | +---+---+---+ | 2 | y | 6 | +---+---+---+  Into results that looks like this:  +---+---+-------+ | A | B | C     | +---+---+-------+ | 1 | x | 2 3 4 | +---+---+-------+ | 2 | y | 5 6   | +---+---+-------+   The rows that have similar values from attribute A are grouped into one column though the different values from C are merged together.  Please let me know if you can help. Thanks


Unity bounds includes the center of the scene

I'm trying to get the bounds of an object and put a box around it.  Sounds simple right? I just encapsulate all the bounds together and use its center and size to do so.  But the problem is one corner of the box is always at the center of the scene, like a part of the object is there, unless the center of the scene is in the bounds.  This is when object is at the center   This is when it isn't  This is the code i'm using:      public static Bounds Calculate(Transform TheObject)     {         Renderer renderer = TheObject.GetComponent<Renderer>();         Bounds combinedBounds = new Bounds();         if (renderer != null)             combinedBounds = renderer.bounds;         var renderers = TheObject.GetComponentsInChildren<Renderer>();         foreach (Renderer render in renderers)         {             if (render != renderer) combinedBounds.Encapsulate(render.bounds);         }         return combinedBounds;     }


Prime ideals in $F[x]$ when $F$ is a field

Let $F$ be a field. Prove that the polynomial ring $F[x]$ in one variable over $F$ has infinitely many prime ideals. All I can think of if that if we can show there are infinitely many irreducible polynomials in $F[x]$ but I see no reason why that should hold, I have no information about the field $F$.


Webmaster Tools, www and no-www, duplicate content and subdomains

My company has two websites a main one at www.example.com and one at subdomain.example.com which is a subdomain of the first and is our self hosted blog.   The way Google sees these with the www or no-www (called naked for now on) is that each of these actually are different when the www or naked version is used/not used in the front of the domain. I completely understand this. It is also advised that both should be set up in the Google Webmaster Tools, which I have done. Correct me if I am wrong on that in regard to having both set up.  Now the way it appears is that we can set a preferred domain up in Webmaster Tools only at the root domain level. The subdomain cannot have this and actually says the following:  **Restricted to root level domains only**.  So it appears that the domain should follow what the root domain says, which on our preferred one says to display the www.example.com and not the naked version. That is one issue I have in that one displays one way and the other displays another.   Is it that we have the wrong redirects in place for the subdomain? Another question is does this have any affect on SEO in regards to duplicate content on the web in how we have set this up?


I submitted a paper to a journal one week ago. What does "Awaiting ME Processing" mean?

The status from the very 1st day is "Awaiting ME Processing". Can someone tell me what does it mean?


How to make program autostart only in GNOME

I use both GNOME and KDE SC. In GNOME, I use Docky but I do not use it with KDE. So, I would like Docky to start up only when I login into GNOME not KDE. In KDE, there is an option to make a program autostart only in KDE. But I cannot find any such option in GNOME.    How can I do this?    Thanks in advance.


I recently submitted an article to a math journal and got a response from a reviewer, with an attachment. In it, I have found some good  advice that could improve my article tremendously.  I am a bit suspicious of its accuracy since it could resolve what I have been working with for some months in a few  sentences.   But anyway, it was enough for me to ask the reviewer for coauthoring with me.   My question would be, does it often happen that an author asks a referee for coauthoring during the review process? Or could it even be possible?  I was given a month to revise my article, but the chance that I could revise successfully by myself seems to be fat.  I would be looking forward to any advice.  Thanks in advance.


How can I improve this code to not be hacked easily?

I am a victim  of sql injection, they hacked into my mysql database and they started deleting data and also they changed passwords. I thought using PDO am safe. This is my login page for PHP. I need help where did I go wrong here which led to the attacks. I would like to be advised on how to improve this code to avoid similar attacks to happen again.   <?php session_start(); ?> <?php require_once('dbconnect/pdo.inc.php'); $username = (isset($_POST['username'])) ? trim($_POST['username']) : ''; $password = (isset($_POST['password'])) ? trim($_POST['password']) : ''; $pas = md5($password); $redirect = (isset($_REQUEST['redirect'])) ? $_REQUEST['redirect'] :         'index.php'; $result = array(); $result['error'] = FALSE; $result['message'] = ""; //if(isset($_POST['submit'])){  if (empty($password)) {     $result['error'] = true;     $result['message'] = "enter password"; //json encode and echo reusult.     $res = json_encode($result);     echo $res;     exit(); } if (empty($username)) {     $result['error'] = true;     $result['message'] = "enter username"; //json encode and echo reusult.  $res = json_encode($result);     echo $res;     exit(); } $query = ("SELECT username FROM users WHERE username=:username  AND password =:password"); $query_login = $con->prepare($query); $query_login->execute(array(     ':username' => $username,     ':password' => $pas)); $results = $query_login->rowCount(); if ($results > 0){     $_SESSION['username'] = $username;     $_SESSION['logged'] = 1;     $result['error'] = false;     $result['message'] = 'Successfully logedin';         header('Location:index.php');     $res = json_encode($result);      echo $res; } else{ //set these explicitly just to make sure      $result['error'] = true;     $result['message'] = 'User name invalid';     header('Location:login.php');  $res = json_encode($result);     echo $res;     exit(); } //  } ?>   //This is the way I connect to the database   <?php function connected_Db(){      $dsn  = 'mysql:host=localhost;dbname=usaDB;charset=utf8';     $opt  = array(         PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,         PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC     );     #echo "Yes we are connected";     return new PDO($dsn,'brrmingham','m#67yhfdelkomngf_()likf4', $opt);  } $con = connected_Db(); if($con){ //echo "connected "; } else { //echo "Connection faid "; exit(); } ?>


I am travelling to Iceland from Mumbai and have to change flights at Heathrow. From terminal 4 to terminal 2.   Do I need a transit visa?


I have to analyze 8 raster layers, 5 of them are 0.5 degree resolution and the other three are 0.05 degree resolution.  Firstly, should I resample the 5 to finer resolution (0.05 degree) and if possible how to do this.  Secondly, if it is better to resample the 3 to the resolution of the others (0.5), what tool do I use to do this without changing the values of the raster. The 3 fine resolution rasters are livestock count data.  I am using ArcGIS Desktop 10.2.


Let $V$ be an inner-product space, finite-dimensional over $\mathbb{C}$. Let the operator $T:V\to V$ satisfy $$T^2 = \frac{1}{2}(T+T^*)\,.$$  I'd like to prove that $T$ is normal, i.e., $T^*T = TT^*$, and that $\,T^2 - T = 0\,$ holds.  So I've tried the obvious: $$ \langle T(v), T^*(v) \rangle = \langle T^2(v), v \rangle = \frac{1}{2} \langle (T+T^*)(v), v \rangle = \frac{1}{2} \left(\langle T(v),v \rangle + \langle T^*(v), v\rangle \right) $$ I don't see we can infer something smart from those equalities. Any ideas?


I have problem in clean url i am trying to enable it but it showing radio buttons deactivated and showing Your system configuration does not currently support this feature.  My web is on shared hosting under the sub directory Like This  The main Web is "Oceanwis"  Your help is really appreciated


Having multiple Drush instances for different core versions

So in my environment, I have some websites on Drupal 7 and some on Drupal 8, and since the latest Drush 9 works with Drupal 8.4+ I was wondering if there's a way to be able to have both Drush 9 and (put another version here) to work on both major Drupal versions.  I'd like to be able to just use drush as my main alias and not define different aliases for different Drupal versions.


Why isn't calling a static method by way of an instance an error for the Java compiler?

I'm sure you all know the behaviour I mean - code such as:  Thread thread = new Thread(); int activeCount = thread.activeCount();   provokes a compiler warning.  Why isn't it an error?  EDIT:  To be clear: question has nothing to do with Threads.  I realise Thread examples are often given when discussing this because of the potential to really mess things up with them.  But really the problem is that such usage is always nonsense and you can't (competently) write such a call and mean it.  Any example of this type of method call would be barmy.  Here's another:  String hello = "hello"; String number123AsString = hello.valueOf(123);   Which makes it look as if each String instance comes with a "String valueOf(int i)" method.


Its the standard float issue. You have a bunch of floating elements inside a parent container div. Since the childs are floating, the parent doesnt expand to include all of them.  I know about the clearfix solution as well as setting the overflow property on the parent container div to "auto" or "hidden". To me setting the overflow method seems much nicer as its just one property. What I want to understand is when does the clearfix approach has advantage over this method cause I see it being used extremely often.  P.S. I am not concerned about IE6.


How can I get just one Parameters from different script

I have two different scripts. I want to get one variable from the script to use another script. I try that method but its give me this answer shown below.   scrip1.py  a=7 print(a) c =10 print(c) b=5   script2.py  from script1 import b print(b)   result is :  7 10 5   How can i get just value of b and the output will be ? :   5


I have a combinatorics problem, and I don't know my answer is correct or not.   The problem is the following :   Assume that X people line up to get into Y different clubs. How many ways are there to do it? (The people are distinguishable and the order people are in line matters.)  My attempt : we have Y different kinds of clubs. So, we have ${X+Y-1 \choose X}$. But, $X$ people are distinguishable, we have to permute them, $X!$. Thus, the final answer is $X!{X+Y-1 \choose X}$. Is that right answer?


This is the error I get when I run google-chrome in the terminal:  [0505/065554:ERROR:nss_util.cc(94)] Failed to create /home/pipi/.pki/nssdb directory. [0505/065554:ERROR:nss_util.cc(94)] Failed to create /home/pipi/.pki/nssdb directory. [3545:3545:0505/065557:ERROR:nss_util.cc(94)] Failed to create /home/pipi/.pki/nssdb directory. [3545:3545:0505/065558:ERROR:process_singleton_posix.cc(417)] readlink failed: Permission denied [3545:3545:0505/065558:ERROR:process_singleton_posix.cc(253)] readlink(/home/pipi/.config/google-chrome/SingletonLock) failed: Permission denied [3545:3545:0505/065558:ERROR:process_singleton_posix.cc(253)] readlink(/home/pipi/.config/google-chrome/SingletonLock) failed: Permission denied [3545:3545:0505/065558:ERROR:process_singleton_posix.cc(277)] Failed to create /home/pipi/.config/google-chrome/SingletonLock: Permission denied [3545:3545:0505/065558:ERROR:process_singleton_posix.cc(417)] readlink failed: Permission denied [3545:3545:0505/065558:ERROR:process_singleton_posix.cc(253)] readlink(/home/pipi/.config/google-chrome/SingletonLock) failed: Permission denied [3545:3545:0505/065558:ERROR:chrome_browser_main.cc(1213)] Failed to create a ProcessSingleton for your profile directory. This means that running multiple instances would start multiple browser processes rather than opening a new window in the existing process. Aborting now to avoid profile corruption.


Data from multiple lists using single REST API call

I need to get some data based on a key field from multiple lists. For this, I may need to do multiple API calls. Is there any way to avoid this ? To get all the data from multiple lists in a single API call ?


I have a question regarding the test for independence for matrices. If we have 3 vectors A1, A2, A3, then while creating the augmented matrix, do we write the 3 vectors horizontally (transpose) or do we write them vertically. I have seen both and I get confused which is the right way. If I am unable to express myself, I have attached examples.    This is the first picture. X1 was the 4 by 1 vector (1, 2, -1, 0)^t which got written horizontally.   In the second picture here,    the vectors are not written horizontally.   What is the reason behind choosing to write the transpose sometimes? Am I missing something? Any help will be really appreciated. Thank you!


How to revoke my old paper from a fake journal (waset.org)?

It was like more than 6 years ago, I was an undergrad senior in a south asian university, we did not have much internet connectivity back then.   I wanted to publish something on a journal/conference to get a feedback on my undergrad thesis (I was curious to know about the quality of my work) and submitted a paper to one of the journals listed on that notorious .  I was young and novice, above all, I had no idea that people could do such a scam with intellectual issues like "research papers", anyway.   but the thing is that when I search my name on a web search engine (google, duck-duck-go etc.), that biggest mistake of my life still comes up on the first page, I am now near the end of my PhD and looking for an academic/research job. So, I wanted to communicate with them so that I can request them to revoke my paper.  However, their site does not provide any specific contact address/person to whom I can discuss with.   I have no wish to resubmit that to any other place, after 7 years now I can understand that my undergrad thesis work was too "trivial" to be "published".   Is there anyone who is in the similar situation? and is there any way to retract the paper from  ?  any pointer will be greatly appreciated.   Apology: I am feeling very uneasy to share the link of my paper, but their website is provided.


Prove the absolute value function of a continuous function is continuous

Suppose that $f$ is a continuous function defined on an interval $I$. Prove that $|f|$ is continuous on $I$.  Our definition of continuity: Let $I$ be an interval, let $f:I\rightarrow\Bbb{R}$, and let $c\in I$. The function $f$ is continuous at $c$ if for each $\epsilon>0$ there exists $\delta>0$ such that $|f(x)-f(c)| < \epsilon$ for all $x\in I$ that satisfy $|x-c|<\delta$. The function $f$ is continuous on $I$ if $f$ is continuous at each point of $I$.


Does Ubuntu update after a new Debian version is released?

I'm not 100% clear on the relationship between Ubuntu and Debian. It seems like Ubuntu is (or was, at some point) some sort of fork of Debian; and that they share the same package manager (Ubuntu uses the unstable something and Debian uses the release or stable thing).  My question: there was a  (Debian 9 as it so happens). Will the next version(s) of Ubuntu be updated to use something from Debian 9?   Or are the two distros pretty much independent now?


Is the site association bonus taken into account for Brunhilde hat?

The  is described as:     earn 150 reputation points on three different sites (not including Stack Overflow) within 15 days.   Does the +100 site association bonus count towards the required 150?


Getting the average value of the list items value

Okay so, I'm getting my sharepoint listItems, and i want to count the average value of "_x0072_zb6" which is a price column, right now i'm getting the following error: Cannot read the property value of null ( elmt ) and Error 403, forbidden, please help!  function VisaLista() {     namn = document.getElementById("txtNamn");     var camlQuery = new SP.CamlQuery();     camlQuery.set_viewXml(     "<Where>" +     "<And>" +     "<Eq><FieldRef Name='Title'/><Value Type='Text'>" + namn + "</Value></Eq>" +     "<Or>" +     "<Eq><FieldRef Name='Prioritet'/><Value Type='Text'>Hög</Value></Eq>" +     "<Eq><FieldRef Name='Status'/><Value Type='Text'>Startad</Value></Eq>" +     "</Or>" +     "</And>" +     "</Where>");     listItems1 = list.getItems(camlQuery);     clientContext.load(listItems1);     clientContext.executeQueryAsync(OnSuccessVisa, OnFail); }     function OnSuccessVisa() {         var listEnumerator = listItems1.getEnumerator();         var elmt = 0;         while (listEnumerator.moveNext()) {             var currentItem = listEnumerator.get_current();             elmt = (currentItem.get_item('_x0072_zb6'));              var sum = 0;             for (var i = 0; i < elmt.length; i++) {                 sum += parseInt(elmt[i]);             }              var avg = sum / elmt.length;         }         $("#Kategori1").text = "Medelvärdet för dessa ordrar: " + avg     }


Are there any good resources and step by step tutorials on Simplex Noise? I have been Googling on it for a while now but I really can't find any good ones. I kinda understand the theory behind it but I have no clue how it works from A to Z and how to implement it.   (I am not looking for a library)  Why this is not a duplicate of   In this question I am asked how Simplex Noise works from A to Z, rather than how the coordinate system gets converted.


Since I have stopped working, I started to learn English at home.   Since I had stopped working,I started learning English at home.    Are both questions having the same meaning in this context?


I am new to programming.When I find this strange result while I learning python.  >>> 10/-7 -2


Mathematics GRE for graduate engineering admissions

I would like to apply for a Ph.D. in engineering in the US. My area of interest (control systems/dynamics) is closely related to (applied) mathematics. Would a reasonable but not outstanding result (e.g. 70%+) in the GRE mathematics subject test give me an edge during the admission process? To be more specific, I would like to understand how relevant is mathematics subject test for admission to (mathematics-heavy) engineering programs (subject tests are usually not required for admission to graduate engineering programs) and what would be considered a high/low subject test score in this context?


Prove that $n+2$ points in $\Bbb R^n$ cannot all be at a unit distance from each other.

I saw this on the FB group "Actually good math problems" where one solution was an illegible photo and the other involved intersecting spheres. I have a solution. I'd like to see how many good answers I get before I post it.  If $S$ is a set of $n+2$ points in $\Bbb R^n$ (with $n\in \Bbb N$) with the usual (Cartesian) norm, show there exist $2$ distinct $p,q\in S$ with $\|p-q\|\ne 1.$


I came across this problem while looking at Putnam problems a while ago:     Alan and Barbara play a game in which they take turns filling entries of an initially empty $2008 \times 2008$ array. Alan plays first. At each turn, a player chooses a real number and places it in a vacant entry. The game ends when all the entries are filled. Alan wins if the determinant of the resulting matrix is nonzero; Barbara wins if it is zero. Which player has a winning strategy?   I figured out the answer to the question they asked, but it made me wonder about a different question, which might not have an easy answer. For the original question, Barbara has a winning strategy. She can force the first two columns of the matrix to be the same, by copying whatever Alan plays in one column into the other column.   My question is: can Barbara still win if she goes first instead of Alan? She can't use the same strategy as before, because now Alan can force her to play in the first two columns by filling up the rest of the grid.   It might seem likely that Alan would have a winning strategy if Barbara went first, since he gets to control the last entry of the matrix. On the other hand, from sketching out a few games on paper, I concluded that Barbara could win whether she went first or second on both a $2 \times 2$ or a $3 \times 3$ matrix, so maybe that pattern continues to hold for larger matrices. I also sketched out a few games with a $4 \times 4$ matrix, but I wasn't able to come to a conclusion for that one.   Edit: Maybe the $2008 \times 2008$ array is too large of a problem. I would be equally happy knowing the answer to the $4 \times 4$ problem: is there a winning strategy if Barbara goes first in a $4 \times 4$ array?  Edit 2: It looks like my question was asked before:


Good block size for disk-cloning with diskdump (dd)

I use dd in its simplest form to clone a hard drive:  dd if=INPUT of=OUTPUT   However, I read in the manpage that dd knows a blocksize parameter. Is there an optimal value for the blocksize parameter that will speed up the cloning procedure?


is my MYSQL injection statement vulnerable?

I believe this statement is vulnerable for injection, but am unsure.    Any help in this regard?  Thanks.  function CheckUserLogin($userName,$password) {     $sql="SELECT user_id           FROM users           WHERE user_name='".addslashes($userName)."' AND password ='".addslashes($password)."'";         $this->query($sql);     if($this->movenext()>0)     {         return $this->col['user_id'];        }     else      {         return false;     } }   The query function is as such  function query($_query){     list($usec, $sec) = explode(" ",microtime());     $time_start  = ((float)$usec + (float)$sec);       $this->query = $_query;     $this->result = @mysql_query($_query, $this->link_id) or die("error in sql query

".$_query."
.mysql error : ".mysql_error($this->link_id)."
");      list($usec, $sec) = explode(" ",microtime());     $time_end  =  ((float)$usec + (float)$sec);     $time = $time_end - $time_start; }


Determining if an Object is of primitive type

I have an Object[] array, and I am trying to find the ones that are primitives. I've tried to use Class.isPrimitive(), but it seems I'm doing something wrong:  int i = 3; Object o = i;  System.out.println(o.getClass().getName() + ", " +                    o.getClass().isPrimitive());   prints java.lang.Integer, false.  Is there a right way or some alternative?


Is this statement equivalent to Goldbach's conjecture

Given a number $n\ge 3$, then one of these is true: \begin{equation} \begin{cases}2n = (6m-1)+P, \ \ \ P \in \mathbb P, \  6m-1 \in \mathbb P, \ 6m+1 \in \mathbb P \ \ \ \ (1) \\ 2n-1 \in \mathbb P, \ 2n-1 = P + 6k,\ 6k+1 \in \mathbb P \ \ \ \ (2) \end{cases} \end{equation}  In other words, any even number $2n$ greater than $4$ can be written either as a sum of a prime and another prime which is lower of a pair of twin primes or, if this cannot be done, then $2n-1$ is a prime and it can be written as a sum of a prime and a number divisible by six which is one smaller than a prime.  My justification for this is the Goldbach's conjecture.  Assume every even number greater than $2$ can be written as a sum of two primes. Then list every possible way to write $2n+2$ as sum of two primes: $h = \{P_1+P_2,P_3+P4... \}$  Now $2n = 2n-2$. Then $2n$ can be written as a sum of two primes as well, so there must be either some $P_n$ which is a component of some sum in $h$, for which $P_n-2 \in \mathbb P$ or, if no such prime exists, but we have to get the primes for $2n$ from somewhere, so some $P_n$ must be 3 and if $2n+2=3+P_s$, $2n = 1+P_s$ and $P_s$ can be expressed as a sum of a prime and a number $N$, such that $N+1 \in \mathbb P.$   Assume then that what I stated at the beginning is true. Then $2n$ can be written in one of the two forms and thus $2n+2$ is automatically a sum of two primes.  The other form is necessary, take as an example the smallest number for which the $(1)$ fails: $$38 = 19+19 = 7+31 = 37+1. $$ None of these is a lower of a twin prime pair, but $37$ is a prime and $37 = 31 + 6$ and $6 +1 = 7$ is a prime.


I have a my_module.routing.yml file and because of I have multi entity in my module its too big and not pretty.  Is there any way to split it for each entity and include them in one file like , I use below code but it's not work in drupal 8.  acme_demo_user:   resource: "@acmeDemoBundle/Resources/config/routing/user_routing.yml"   I also use absolute path for yml file but it's not work.


What is zero to the power of zero? $0^0$

Evaluate:   $$0^0$$   Would you use this law of indices?     $$x^0=1$$   Or would you use that:     $$\frac{x^n}{x^n}=x^0$$ which would mean $$\frac{0}{0}=undefined$$


I am struggling to verify this identity. I've tried using the Principle of Mathematical Induction, combinatorial proofs, and a generalization of Vandermonde's Identity, all to no avail. It's the $(2n)!$ that's giving me problems.


Why can't I access Area51 from the Stack Exchange App?

I use the iPhone app and I am really happy with it. However, Area51 is not listed in the list of sites to browse. Is there any way to access Area51.stackexchange.com from the app?


A few months ago our website got hacked, similar to what seems to be described in the following -   We fixed the original part of it, by clearing the website itself so we no longer display Japanese hoodie sale pages. I have also run a Wordfence scan which has come up saying the website is clean.  Currently, the issue we are having is that multiple 3rd party domains are still continuously generating links to our domain on their site and Google is indexing them e.g.   justaccounts.com/bumper23075 justaccounts.com/miraculously_G7nOG7nrnO. justaccounts.com/iterate_JeIEbNG0.   (I got these links by going to site:justaccounts.com)  All of these generated links are throwing 404 errors because the path now does not exist. This is causing us to have an extremely high bounce rate as most of our traffic now comes from Japan and surrounding countries to these dead links, and are immediately leaving because the page doesn't exist. This is, in turn, causing us to drop in search rankings massively.  Do you have any suggestions on how I can properly tackle this issue and have it sorted once and for all? Stopping these 3rd party link generations and having our domain show as clean and only displaying URL's submitted in our sitemap?  The steps have been followed to remove the 'This site may be hacked' message and I have also run a 'Wordfence' scan which is showing that the site itself is clean and secured, so the main issue is the 3rd party generated links.  Any help on this subject would be greatly appreciated as it is becoming a serious issue in terms of us utilizing our website properly.


How to copy files between two computers using SSH

Situation: I have 2 computers: Pc_A and Pc_B. I am also using a SSH connection that goes from A to B.   My problem: I have a folder saved on the desktop of Pc_A and I need to copy it to the desktop of Pc_B via terminal. The thing is that once I open the terminal on Pc_A and I connect to Pc_B I'm no longer capable of transferring data from one computer to another...    Question: does anyone have the idea of what should be done in such case?


I have this environment variable set in the system control panel on my Windows 7 machine:  C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\RSA SecurID Token Common;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\110\Tools\Binn\;C:\Program Files (x86)\Microsoft SQL Server\120\Tools\Binn\;C:\Program Files\Microsoft SQL Server\120\Tools\Binn\;C:\Program Files\Microsoft SQL Server\120\DTS\Binn\;C:\Program Files\CaseWare IDEA\IDEA;C:\Program Files (x86)\CaseWare IDEA\IDEA;C:\Program Files\Dell\Dell Data Protection\Encryption\;C:\HashiCorp\Vagrant\bin;C:\Program Files (x86)\Cisco\Cisco AnyConnect Secure Mobility Client\;C:\Program Files\Git\cmd; C:\Python27;C:\Program Files\Amazon\AWSCLI\; C:\Program Files\Splunk\bin   But for some reason none of the programs I'm trying to access like python, aws cli and splunk are not found when I try to run them.  For instance when I try to run splunk it's not found, even tho I clearly added it's bin file to the path:      PS C:\Users\tdunphy> splunk splunk : The term 'splunk' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again. At line:1 char:1 + splunk + ~~~~~~     + CategoryInfo          : ObjectNotFound: (splunk:String) [], CommandNotFoundException     + FullyQualifiedErrorId : CommandNotFoundException   What am I doing wrong?


If there exists $m,n\geq2$ such that $x^{m}y^{n}=yx$, for any $x,y\in M$, then prove that the operation is commutative

Let $M$ be a set, not null, and $*$ an operation that is associative. If there exist $m,n\geq2$ such that $x^{m}y^{n}=yx$, for any $x,y\in M$, then prove that the operation is commutative.    Now, I obtained a result by $x{\rightarrow}yxy^{-1}$ such that $yx=(yxy^{-1})^my^n=yx^my^{n-1}=yx^my^ny^{-1}=yyxy^{-1}$ and from here $yx=yyxy^{-1}{\Rightarrow}xy=yx$.     However, this works only if my set is a group. How can I adapt this to the form of the set?


I have used aluminum foil when I grill salmon because it keeps the oil from running onto the heating element and smoking the fish.  Can anyone suggest a substitute for aluminum foil?


Python slicing - Skips certain number of rows

I currently have 500 rows of data. I want to use the first fifty rows, then skip 50 rows and so on. How do I go on about doing this?


Can Ubuntu Touch be installed on a iPad one

I have an iPad one and would simply like to know if Ubuntu touch can be installed on it and where I can find information on how to do this, I have done many searches on Utube and google! so far nada.  Please help if you can. Best regards Susan.


Can't access host-only network when on two interfaces

I'm trying to use a host-only connection with my VirtualBox VM. My VM is set up and can ping the host (192.168.56.1) on vboxnet0.   If I disconnect the host from my local network (internet access) I can ping the VM no problem. However I would like to be able to access both the internet and the VM. This is what my ifconfig looks like:  enp0s25: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500         inet 10.0.7.30  netmask 255.255.255.0  broadcast 10.0.7.255         inet6 fe80::3e97:eff:fe2b:5d3e  prefixlen 64  scopeid 0x20<link>         ether 3c:97:0e:2b:5d:3e  txqueuelen 1000  (Ethernet)         RX packets 1468619  bytes 1793380003 (1.6 GiB)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 877021  bytes 94509833 (90.1 MiB)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0         device interrupt 20  memory 0xf2900000-f2920000    vboxnet0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500         inet 192.168.56.1  netmask 255.255.255.0  broadcast 192.168.56.255         inet6 fe80::800:27ff:fe00:0  prefixlen 64  scopeid 0x20<link>         ether 0a:00:27:00:00:00  txqueuelen 1000  (Ethernet)         RX packets 0  bytes 0 (0.0 B)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 6212  bytes 278937 (272.3 KiB)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0   Here's the output of route:  [user@localhost] : ~ $ route Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface default         gateway         0.0.0.0         UG    100    0        0 enp0s25 default         gateway         0.0.0.0         UG    101    0        0 vboxnet0 10.0.7.0        0.0.0.0         255.255.255.0   U     0      0        0 enp0s25 10.0.7.0        0.0.0.0         255.255.255.0   U     100    0        0 enp0s25 192.168.56.0    0.0.0.0         255.255.255.0   U     100    0        0 vboxnet0   It appears to me I'm correctly configured to use both interfaces but, like I said, I can't ping the VM (192.168.56.66) while I'm connected on enp0s25.


Can a Wizard learn to cast Cure Light Wounds from a bard scroll?

If a bard were to scribe Cure Light Wounds into a scroll, would it be possible for a Wizard to write it into his spellbook given that it's the arcane version of the spell?  I know about , but I'm unsure if the rules are different when dealing with a Wizard versus a Sorcerer.


How to restore my Mac OS X using time machine onto a new hard drive install?

I have a mid 2010 MacBook Pro and want to install a new hard drive but I'm not sure how to restore my Time Machine back ups (Yosemite) with a new hard drive.


Can someone give me a good reason why users are using ifmodule in their htaccess ? <IfModule mod_headers.c>    Header set Cache-Control "max-age=290304000, public" </IfModule> # Else, doesn't matter. It's fine anyway. Making business #  Isn't this a bad practice ? Why using ifmodule if they should be definitively sure they want to use some rules ? Anyway, is it possible that a module freezes/block/disable suddenly without knowing ?


Looking for old story: Ancient knights charge and take over alien space ship. Conquer aliens by laying siege to cities

The book starts out with human space explorers coming across very tall humans that left earth around a thousand years earlier. Turns out, the tall humans are descended from knights that charged an alien spaceship that landed on earth.  The knights end up conquering the aliens by laying siege to their cities and converting them to Christianity.


SciFi/Horror movie featuring alien city landing in a US desert, forshadowed by cave paintings

I finally registered in hope of finding people who maybe know the movie I have been looking for for ages...  The movie takes place in a very dry country in the States. I would guess it is Texas or so. The protagonist lives in or visits a small desert town and hears about some rumors of a coming event (or something like that). Searching the vicinity of the town he finds some carvings/paintings in a cave depicting some kind of alien city/huge UFO that is going to land.  And well, in the end it really lands and the inhabitants are not very friendly. As far as I can remember they look like humans with armor or cyborgs with huge weapons or so.  The "visitors" came with one or more huge cities the city/cities had a dome or shield and were built upon some kind of structure with landing supports and their leader was marching down some kind of huge ramp, had a big weapon and I think a bald head with pipes leading from his neck/head to his "armor".  Before they did land, they send some scouts who checked the area, oh yeah and this was definitely in color that much I know for sure.  What non American studio could have made such a movie in the 70s or 80s? It definitely was produced in the west.  I watched it as a little kid (thanks dad for the nightmares) in the mid 80s. So it is kinda old.


How can I play audio (it would be like a 1 second sound) from a Python script?  It would be best if it was platform independent, but firstly it needs to work on a Mac.  I know I could just execute the afplay file.mp3 command from within Python, but is it possible to do it in raw Python? I would also be better if it didn't rely on external libraries.


Does this sentence use nominative absolute phrase?

A scientist, he always thinks about what is best for the people.    Is this "a scientist" part a nominative absolute phrase? It seems like nominative absolute phrase has to have a verb or adjective after the noun like this:     The dragon slain, the knight could rest.    It is what makes me confused. I don't think the scientist sentence uses nominative absolute phrase since it only has a noun to describe "he". There is nothing more than a noun. So is it a nominative absolute phrase or not? If not, what's the name of that usage?


Could I be notified when a question I answered is deleted?

I poured my heart out to write a great answer to a question, and I earned a gold badge for it. I'm so proud of the answer that I've even linked to it on the web in several places.  To my surprise, I discovered that the question had been closed without notifying me, and that it had been deleted without notifying me.  Since there already is , this question is specifically about deletions.  Please could I be notified whenever a question that I posted an answer to is deleted? Especially if my answer is long, or earned lots of upvotes. I want to at least be able to fix any links to that question, and maybe convert that answer into a blog post or something, because I really do think it is making the Internet a better place.  Some high-rep users have already found the deleted question that caused me to discover this issue. But I want to be clear that I'm not trying to generate a discussion about whether the deletion was justified or not, I'm pointing out that I was never notified of the deletion, and I think I should have been.  My question is slightly different from , as I want to be notified when a question of my answer is deleted, not necessarily when my question has been deleted.


What's the difference between low energy photons and high energy photons?

This is probably a dumb question. I guess what I'm trying to ask is if radio waves travel the same speed as gamma rays, how do gamma photons carry more energy than radio photons? Do they spin faster? What other energy sources could they carry if they are moving the same speed through space?


Customs + Electronics per Traveller or as Family

My Wife, Daughter and I are traveling to India for 2 months from US. We would be there arriving at Mumbai.  Can we as a family take 1 iPad + 1 iPhone + 1 Camera + 1 my office laptop with me? Please note we are 2 Adults and 1 5 year old.


This question might have been asked before but I have not been able to find it.  How can I find: $$\sum_{i=0}^n 2^{-i}$$ Help?


Finding the derivatives of sin(x) and cos(x)

We all know that the following (hopefully):  $$\sin(x)=\sum^{\infty}_{n=0}(-1)^n \frac{x^{2n+1}}{(2n+1)!}\ , \ x\in \mathbb{R}$$  $$\cos(x)=\sum^{\infty}_{n=0}(-1)^n \frac{x^{2n}}{(2n)!}\ , \ x\in \mathbb{R}$$  But how do we find the derivates of $\sin(x)$ and $\cos(x)$ by using the definition of a derivative and the those definition above?  Like I should start by doing:  $$\lim_{h\to\infty}\frac{\sin(x+h)-\sin(x)}{h}$$  But after that no clue at all.  Help appreciated!


Question with zero answers has an accepted answer

I came across this oddity when I ran , sorted by votes:    That question has zero answers, but its search result summary is formatted as though it has an accepted answer (green box, yellow-highlighted text).  In fact, the CSS class on that div is class="status answered-accepted">.  Perhaps the Skynet Exchange Stack Exchange system has become so intelligent, that it knows the OP solved their own problem (answering it in the question portion of the post), and thus it's marked as "answered-accepted."  Or maybe, after over 5 years, the question has just accepted the fact that it isn't going to get any answers.   Regardless, this seems like a display bug =)


Are the LIGO observations proof of a black hole merger, and what happened to the black holes?

Recent reports claim that the gravitational waves detected by LIGO match up with the signal expected from two black holes merging as predicted by general relativity.  Additionally, the masses of both black holes were estimated. Questions:  How certain are we that the detected of gravitational waves are necessarily from two black holes merging?  Since supermassive black holes are typically at the center of a host galaxy, what happened to the galaxies that contained the two merging black holes?  For example, did their host galaxies merge?    Edit After reading the answers, I understand that the signals detected by LIGO are proof of the validity of gravitational wave generational artifacts as predicted by general relativity.  When additionally gravitational waves, caused by the merger of the supermassive black holes (those which ARE indeed located in the centers of the merging galaxies) will be detected, since mergers of galaxies could be observed by the methods independent of gravitational waves such as registering the fact of the quasar appearance (). Additional questions:  Could someone offer me the historical ASTRONOMY precedent when the second degree of inference (from the mathematical model, being associated with the theory of Physics) was accepted as the discovery of the astronomical object?  Could someone give a reference to trustable scientific publication, with the subject of study being discussion of requirements satisfying claim of astronomical discovery of an astronomical object?  Have independent scientific sources (outside of members of the LIGO team) analyzed methodology and results of the LIGO signal detection, and published their conclusions with regards of what was actually discovered?


I have stored a text  as .txt while saving it in Gedit in Ubuntu 14.04.  But after viewing that folder, which i have stored will have two files with that name but with 'Tilde Symbol' '~' for an another file and it will be hidden!!!  Say 'a.txt' means the folder will contain '~a.txt' too, which can be viewed only by making them unhidden  Why is it so? What does it mean? Any Problem/Error with that?  How to Rectify it?


How to express level of difficulty in exercises?

How would it be possible to have graphic expression of level of difficulty in  like in Stewart's book? Let say, to have those colored rectangles around the exercise number.


Compressing two identical folders give different result

I have two identical folders, with same structure and contents like this:  folder_1   hello.txt   subfolder     byebye.txt  folder_2   hello.txt   subfolder     byebye.txt   if I compress them as tar.xz formats I get two different archives with two different file sizes (just a few bytes, but they're not identical).  $ cd folder_1 && tar -Jcf archive.tar.xz * $ cd folder_2 && tar -Jcf archive.tar.xz *   I get:  folder_1/archive.tar.xz != folder_2/archive.tar.xz   and of course if I md5sum or sha1sum them I'll get two different hashes  And that's my problem... I need to check if a provided archive is identical to the one I have in my storage. I cannot use hashing nor just check file sizes.  Using zip instead of tar.xz works as zip always produces identical achives from identical files. Why is this happening? Is there a way to prevent it?


Drawing digital circuits can become a mess very fast which makes testing those even more difficult. Doing it offline is a painful job with all those wires. So, what GUI software is recommended for building digital circuits and testing them?


I'm iterating through a list of list of strings. I need to print each list in comma separated format except the last element. This is my code.  for(Iterator itr = list.iterator(); itr.hasNext();){     List<String> l = (List<String>) itr.next();     for(Iterator it = l.iterator(); it.hasNext();){        System.out.print(it.next() + " ");     }     System.out.println(); }   This prints something like   listen, silent, tinsel,   How do I format the print logic to remove the comma after the last element. I can do that on for i loop checking the value of i against the last index, but wish to know how to do it with an Iterator in Java.


How to delete all events on many dates all at once but not the whole Calendar in Google Calendar? I tried to click on a date that got an event to delete and dragged my mouse to 2 days after that date, but then I always see "create an Event". I thought I could press backspace or delete to delete all those events.  What I did so far = deleting event one by one :(


Why does the road look like it's wet on hot days?

Often, I'll be driving down the road on a summer day, and as I look ahead toward the horizon, I notice that the road looks like there's a puddle of water on it, or that it was somehow wet. Of course, as I get closer, the effect disappears.  I know that it is some kind of atmospheric effect. What is it called, and how does it work?


If $G$ is abelian, it has a subgroup in every order of $|G|'s$ divisors?

Assume that $G$ is an abelian group, I read somewhere that it can be derived from Lagrange's theorem that it has a number of subgroups that is equal to the number of $G$'s divisors.  Why does it hold? I'm confused...


Does a neutral object has an electric field of its own?

Today in class i have learned that an electric field is basically a region around the charged particle which will cause a force to be exerted on a charged object. I was wondering what if an object is neutral, would it still have an electric field?


Give badges to people for coming back and answering their own question

Someone's asked  the answer being that it's intended to help people learn about the site's functionality. Answering your own question  and there's a feature to .   The number of unanswered questions, on Stack Overflow at least, , so why not encourage people to fill in the blanks by answering their own questions more regularly?  I'm of two minds about the route to go down. I initially though of something like a silver self-learner badge with some conditions as follows: answer your own +3 scored question with an answer with a score of +5 but as there are only  open, unanswered questions with a score of 3 or more it seems fairly pointless.  A better way would be to allow people to earn a "self-learner" type badge multiple times but to stop people from getting it solely for self-answering. You could have a bronze badge (, or whatever) for people who:   Self-answer a positively scored question - This should not be open to negatively scored questions and I'd be wary of 0 scored to stop a deluge of people wanting the badge. That has not received an answer with a score of more than 1 since it was posted - Not completely sure about this but the goal is to answer the questions without answers More than 24 hours after the question was posted - Otherwise FGITW etc; the point is to get all the old questions answered. With a score of 2 or more - Otherwise you could answer it with anything, which is useless for the internet. Maybe +3 might be more appropriate?   There are  positively scored, unclosed questions with 0 answers so getting some of these answered is a worthy cause.


I couldn't find anything about Ubuntu acting as a  receiver or sender.   Can it work at all? Are there hardware prerequisites? Is WiFi a requirement or can it work over LAN or another kind of network connection? WiFi direct seems to be a necessary requirement, is it a sufficient one? (i.e. if a system supports WiFi direct does that mean it supports Miracast?) Are there differences in support between receiving/sending? How is the latency? (compared to the competition, i.e. VNC, commercial Miracast devices, etc.) How do I actually use it, if it's difficult?   Specifically, I plan to use it together with an Android phone (4.x Jelly Bean).


How do I see that every left ideal of a square matrix ring over a field is principal?

As the question title suggests, how do I see that every left ideal of a square matrix ring over a field is principal?


Annihilator of a finitely generated torsion module is nonzero?

Let $R$ be a commutative ring  and $M$ a finitely generated torsion $R$-module. Then the ideal $\mathrm{Ann}(M)$ is nonzero?   If $R$ is integral domain, this trivially holds since any two ideals have nontrivial intersections.   Add: I say $m\in M$ is torsion, if there is a nonzero element $r\in R$ such that $rm=0$.


Trend & Seasonality Determination in Time Series without looking at Graph

Most of the articles I have read describe determining Trends and Seasonal (TS) effects through rolling your eyes on Graphs. Graph is a nice visual representation,  but I am looking a way in either Python , R or through any other way and discover TS. In short I want to feed my time series data to some program in backend and through output values I determine Trend is Yes/No or Seasonal effects exists in my time series Yes/No. Will really appreciate your ideas. Thanks


implement xxtea algorithm that accepts hex value

I have to encrypt a code with XXTEA algorithm.  cipher = 16 byte key = 8 byte  Example : key: 0xAA 0xBB 0xCC 0xDD 0xAA 0xBB 0xCC 0xDD 0xAA 0xBB 0xCC 0xDD 0xAA 0xBB 0xCC 0xDD  msg : 0xFF 0xFF 0x87 0x30 0xFF 0xFF 0x87 0x30  And I expect this encrypted result  : 0X24 0x81 0xCE 0x89 0xA5 0x58 0x57 0x35  Now I'm using this code :   But for me is more difficult to use this code with hexadecimal byte values, because the byte function gives me the wrong value.  How can I implement an algorithm that accepts hexadecimal value and return encrypted value in a byte array  EDIT : I know how convert hex dump string to byte array (i learned it on stackoverflow =D ), but my problem is that if I use byte[] encrypt(byte[] data, byte[] key) I obtain a wrong result.


If so many people use set.seed(123) doesn't that affect randomness of world's reporting?

It seems like everyone just uses set.seed(123) or set.seed(1234) when they are doing random sampling.  If so many people use just a select few integers for set.seed(), doesn't that mean that everyone is drawing from the same state of the random number generator and therefore all results are not a true random sample?


Ubuntu 15.04 not showing the partitions after installing along side windows 8.1

I have dual boot system with Ubuntu 14.10 and Windows 8.1, both 32bit, with  5 partitons in windows 8.1.  I have insatalled Ubuntu 15.04 64 Bit. Now the 5 windows partitions are not visible and I cannot boot into Windows 8.1. How can I recover my partitons without loosing data.  Note that GRUB Menu is not showing the option to boot into Windows 8.1.  Here's the output of sudo parted -l, run from a live Ubuntu:


So, I'm having problem downloading apps from Play Store because apparently, I have insufficient space on device. The app I want to download is of only 12.68 MB and my system storage has 113 MB, phone storage has 596 MB, and SD card has 1.46 GB available.  I tried cache cleaning, uninstalling unwanted apps, moving the movable apps to SD card but it still won't work.  The device I'm using Micromax Bolt A089 with a 4 GB SD card.  Please help. Thank you.


I have a texture node, I want to keep as it is and try another texture creating another texture node. I don't want to use the same texture node to try both.  How can disable node in node editor temporarily? In Nuke, it used to be d (for disable). Pressing d, of course, does not work in Blender. My intuition says there might be similar in Blender.


This morning my dual boot (ubuntu 16.04/Win10) Lenovo x230i laptop showed the GRUB2 menu on power up, then decided to hang dead. After reboot it behaves as if there is no bootable disk, even though it sees HDD in BIOS and is able to run bad sector check on it.   Loading from Ubuntu Live CD I can not access the /dev/sda disk by any means, all I see is 467 Gb of unallocated disk space and i/o error.    Any routine to try and recover the HDD? If my HDD is (like it probably is) dead, any way to recover data?   Update:  Lenovo bad sector check fixed like 400 sectors, and now the disk can be accessed with no error. It still appears as unallocated space with no partitions. Gpart program is now doing is check and seems to have found two partitions 349 mb each (the system ones). I assume the hdd must be fried and I can get some data out at most.


Append a new row to a table using jQuery

I'm using the following code trying to append a new row to jquery but it's not working.  $('#search-results > tbody').append('
Test	test@test.com	07777777777	ocf83or	1pm
');   My table is setup like so:

             Name	             Email	             Phone Number	             Car Reg.	             Time

   EDIT  My full code is actually:  $('#search').submit(function(event) {     event.preventDefault();     $('#search-results > tbody').append('
Test	test@test.com	07777777777	ocf83or	1pm
'); });


What is the command to: Modify the "cat" command to automatically number paragraphs. These are separated by a single blank line.


There are $40$ letters and $40$ envelopes with addresses. The letters are put in envelopes at random. What is the expected number of letters in their corresponding (correct) envelopes ?  One envelope can hold only one letter.  I start with $E(X_i)=1\cdot\dfrac{1}{40}+0\cdot\dfrac{39}{40}=\dfrac{1}{40}$.  $X_i$ being the $i^{th}$ letter placed correctly or not ($1$, if correctly placed and $0$, if not). I need to calculate the expected count of letters assigned correctly.  Then add up all $\implies$ $E(X_1+X_2+\ldots+X_{40})=\underbrace{\dfrac{1}{40}+\dfrac{1}{40}+\ldots+\dfrac{1}{40}}_{40\text{ times}}=1$  Now my doubt is that if I put $39$ letters correctly, the $40^{th}$ one will be automatically assigned correctly . So should I add only $39$ times ?   Any other mistakes I may be doing here ? Please advise.


Distance between particles in pair annihilation (or any other matter antimatter collision)

Imagine a pair of electron and positron colliding in , which produces two gamma photons: $$e^+ + e^- \longrightarrow \gamma + \gamma $$ My question is that what exactly happens when two particles reach to each other. In other words, does the distance between them come to zero? If not, how does this relate to Heisenberg's uncertainty principle?


Length of stay in the Schengen area with a Turkish “special passport”

I have a Turkish “special passport” which exempts me from the requirement to hold a visa for the Schengen area.  My arrival date is: 13 June 2015, 11.00am My departure date is: 10 September 2015, 11.55pm  Do these dates exceed the limit of stay in the Schengen area?


jQuery : on horizontal scroll tell which element is in viewport

I only found answers for similar problems with vertical scrolling.  I have elements within a parent div, these elements have the same class and their parent is scrollable left and right. Only one of its children can be fully visible. I want to be able to tell which one is fully visible whenever the parent is scrolled :

     [...]


Is it true that, prior to puberty, there are no physical differences at all between boys and girls (except for their private organs)

And that even their physical appearances are exactly the same? This seems very counterintuitive and goes against many people's personal experiences and observations when they were kids. But i have comes across claims that prior to puberty, there are no differences in size, strength, speed or even physical appearance. How true is this?


Can I host multiple sites with one Amazon EC2 instance

I currently have VPS server and I pay around $75 per month and I get:  40GB HD 2Gb RAM 100GB BW 6 core cpu (but i dont use much)   I have only one live website running and traffic is only max 100 user visit per day. I mostly do the my testing stuff and some of my inter sites for playing with coding.  But I do need one server.  I am thinking of moving to Amazon EC2 if the price diff is not so much because then I can learn some more stuff.  I am thinking of getting the 3 years Heavy utilization Reserved instance because my server will be running all day and night. I tried their online caluclator  with  Medium Instance Heavy reserved for 3 years for EC2 it comes $31 per month(effective price) and for EBS and S3 , I think even if thats it $40 for all other stuff. I will be at no loss for what I am getting at present. Am i correct or I missed something??  Now In my current VPS I have Apache for PHP sites and MOD wsgi for python sites.    I am not sure if I will be able to do all that stuff in Amazon EC2. Can I host python and PHP sites both in Amazon EC2 instance using Named Virtual Hosts and Ngnix


One can use . However Preview on Mac OS X 10.7 does a too hard compression for my taste. There is only one compression setting.  Are there alternative tools that allows you to adjust the compression ratio?


Difference between int* p and int *p declaration

What is the difference between an int* p and an int *p declaration?


Irreducibility of $f_p(x^{p^{c-1}})$ when given $f_n(x)=x^{n-1} +x^{n-2}+.....+x+1$ where $n$ is positive integer.

For a positive integer $n$  let $f_n(x)=x^{n-1} +x^{n-2}+.....+x+1$  then what can we say about $\displaystyle f_p(x^{p^{c-1}})$ For every prime $p$ and every positive integer $c$ , is it reducible or irreducible over $\mathbb{Q}[x]$. Solution i tried - I know that for $f_p(x)=x^{p-1}+x^{p-2}+....+x+1 $ is a cyclotomic polynomial and irreducible over $\mathbb{Q}[x]$ but how can i use this to show that $\displaystyle f_p(x^{p^{c-1}})$  is reducible or irreducible over $\mathbb{Q}[x]$ ? please help Thank you


Difference between Grassmann and Stiefel manifolds

I'm working on an optimization problem on manifolds and I'm having a bit of a conceptual issue with choosing between the Grassmann and Stiefel manifolds. Grassmann(2, 3) is the linear subspace of dimension 2 within the space $\mathbb{R}^3$, so all planes through the origin. So a point on the manifold corresponds to a plane, invariant to linear mixing of support vectors. Stiefel(2, 3) would be all possible planes through the origin that are the span of two orthonormal vectors. So my questions are:   Does that mean that a point on the Stiefel manifold is also a point on the Grassmann manifold (in the sense that all linear subspaces of a given span can be reduced to the same orthonormal components)?  What do I gain by optimizing on the Grassmann vs the Stiefel manifold, if the parametrization of the points is the same?


Star rating not showing in rich snippets

We've recently been doing a lot of work on our site's SEO (www.betterthanreviews.com). We recently did a push to update the rich snippets breadcrumb, meta description, and star rating.   After giving Google some time to index the site, it has updated the breadcrumbs and meta descriptions for our review pages, but the stars are still not showing. This is currently how it appears on a Google search (link to the actual page: http://www.betterthanreviews.com/home-security/livewatch):     This is what the Rich Snippets is supposed to look like, and how it appears in Google's testing tool:    More context: As seen in our html, we are using schema.org language. We initially were using schema.org/Corporation for the site, but we now have the page labeled as schema.org/HomeAndConstructionBusiness because Google will not show star ratings for the Corporation language. However, in our Webmaster Tools, the Structured Data is still showing the Corporation language, which could be a potential issue.  Here is a look at some of the coding that we used. But it can be looked at closer by inspecting the element:

         <meta content="4.5" itemprop="ratingValue" title="4.5 out of 5 stars" class="star-rating-readonly">            <meta content="2013-12-05" itemprop="datePublished">
Way better than my previous system

Scott H.
             •
2 months ago

I love it! The experience I have had so far is extremely positive. I had another alarm system before and I didn't like it but this one is really nice. I am telling everybody about it.

   Any suggestions for how to fix this?


Even after properly installing the Pixel 2 device emulator, Android Studio is giving an error that "The user doesn't have permission to use kvm(/dev/kvm).  Changed the permission with the command "chmod u+x /dev/kvm". But that didn't work.The character-device file became executable but still the error persists. Android device emulator refused to open.


Is it enough to submit an XML file to get Orphan pages indexed and ranked?

We have our sitemap submitted to WMT. But we have a lot of Orphan pages on our website, and it seems that they do not rank or do not appear on search, therefore, hardly have any traffic or no traffic at all.   My theory: why would Google rank the pages that the own website do not link towards them. So we should add at least one link to each of those pages. (Because they are relevant pages to our website)  But how does it really work? Is it enough to submit a sitemap to WMT to have orphan pages indexed and ranked?


My teacher told  me that pressure variation is maximum at mean position in a sound wave. Though by proof of pressure wave and displacement wave, I am convinced but in understanding the physical meaning I am facing a problem as I have a counter argument. According to me pressure variation should be maximum there at extreme position because  pressure is maximum due to the fact that density is maximum as all particles come closest to each other due to compression.Hence by this argument the claim that pressure variation is maximum at mean position contradicts my understanding. please help


Modulo arithmetic: finding "c" when there is a number attached to it

I am fairly new to number systems and notations. I have a problem where I need to find $c$ in: $13c ≡ 27a − b^{3} \mod (43)$ given that $0 \leq c < 43$. Also, $a ≡ 27 \mod(43)$ and $b ≡ 19 (\mod 43)$ where $a$ and $b$ are integers. I know that the procedure is to solve the right-hand side, so, in this case, it should be: $c = 27 *27 - 19^{3} \mod(43) =  - 6130 \mod(43) = 19$ Now the $13$ one that is attached to $c$, should it also go into the equation thus c = 19 / 13? But, is weird since $c$ is supposed to be an integer, just like $a$ and $b$. Any clue?


We define a set $S \subset \Bbb{R}^n$ to be star convex if there exists $a \in S$, such that the line segment connecting $a$ and any other point in $S$ lies entirely in $S$.  I would like to show that it's simply connected.  Can someone verify my proof?  The set $S$ is certainly path connected since given $x,y \in S$, we can construct a path from $x$ to $a$ and $a$ to $y$ , and so adjoining the paths yields a path from $x$ to $y$.  Also given any loop $p(r)$, $r \in [0, 1]$, we have a straight-line homotopy  $$H(r, t) = ta + (1-t)p(r)$$  with $H((r, 0) = p(r)$ and $H(r, 1) = a$, so $p$ is homotopic to a point, meaning $S$ is simply connected.


No, I haven't already raised this flag (not here, anyway)

So for whatever reason I was going through  looking for questions that had slipped through the retag/migrate net. I found , which clearly didn't belong on SO, and probably would be migration-rejected here due to low quality; however, I can't custom-close-vote (not enough rep), and flags don't have a custom option. I flagged it for migration in the hope that it would be processed correctly.  I then came across , and decided to use the same tactic -        No, I haven't! (Apologies for the poor freehand-circle quality; the Surface RT is not very conducive to drawing them.)  Have I done something wrong and been covertly banned from raising close flags? Is there a new one-outstanding-close-flag limit? Is there a new no-more-close-flags-while-you-have-an-outstanding-migration-flag limit? Is this just a plain old bug?    Update: Turns out I flagged it two weeks ago, and the flag was still waiting for review. *facepalm*


I am presently riding a hybrid that apparently is a bit too small for me, and I'd like to replace it with a road bike. Having ridden this improperly-sized bike for as long as I have (about 8 months, including one MS150), I am interested in making sure that the next bike I buy is properly sized.  The sizing numbers published for different bike models are only somewhat helpful, because a 54cm bike, even of the same type, will fit different people depending on who made the bike. It would have been more helpful if the sizing was listed as a range of heights for riders (such as, "best fits riders from 175 to 185 cm").  Somewhat complicating the issue is that (as I have mentioned in another question) I am chronically short of funds, and there is a high chance that I'll be buying something off of Craig's List or some other such place. I don't want to waste the seller's time by trying the bike if there's any chance that I won't buy it. I'd much prefer to know when I show up to make the purchase that the bike is manufactured for a rider of my height.  The same goes for mail-order. If I go this route, I want a reasonable certainty that the bike is made for someone my size. I don't want to deal with the hassle of returning a bike that doesn't hit my own personal Goldilocks zone.  I'd also rather not trouble bike shop personnel to let me try a bike to see if the sizing is right unless I'm ready to buy from that shop (possible but by all means not certain); I like to think that I'm a golden rule sort of person and using their time in this way seems too much like taking advantage of them. However, if this is considered by them to be a cost of doing business, then it's not a show-stopper.  That all being said, what's the best way to go about finding what size bike will fit me best? (If it helps to be more specific, I'm mostly interested in a road bike.)