uwsgi errno 24 too many open files on CentOS / nginx

I have a python bottle app being served by nginx and uwsgi.  After running for a very few hours, I start getting a 500 error from the web app, and in /var/log/messages I see:  uwsgi: OSError: [Errno 24] Too many open files   lsof for the failing process shows 1023 files open  I've added fs.file-max=200000 to /etc/sysctl.conf  I've added to /etc/security/limit.conf:  uwsgi    soft  nofile 10000 uwsgi    hard  nofile 30000   I've done sysctl -p, and I've rebooted the machine. I still get the app failing when it hits 1,024 file descriptors.  Am I missing some uwsgi configuration, or something else? I can't seem to convince CentOS to give my app more files.


After trying to delete apache and tomcat, and now trying to reinstall apache 2, I am missing the init.d/apache2 file to start/stop my server.  I am not sure if the new install actualy worked, and my apt-get purge apache2 didn't remove everything in the first place!  How can I get the init.d/apache2 file to test if server starts / is installed properly (I had removed files and directories manually)?


What is the meaning of 'N-SING' in the Collins COBUILD dictionary?

N-SING represents singular noun according to the explanation in the Collins COBUILD dictionary. Can I interpret it as a noun that is countable but unable to be used in plural form and only able to be used in singular form?


How to calculate the exponential inverse in elliptic curve Diffie-Hellman?

In Diffie-Hellman over $Z_p$, I know that if I choose a random $a$ in $Z_p$ and compute the modular inverse mod p-1, not mod p, then, with generator $g$ of my group, I can compute, for example, $(g^{ab})^{(a^{-1})} = g^{aa^{-1}b} = g^{b}$.  I am asking if a similar process is possible over elliptic curves? If I have a generator $P$ and I choose a random $a$ and compute $aP$. How do I do about calculating $a^{-1}$ such that $(aP)a^{-1} = P$?


Looking libunwind.h docs(),  All functions(ex.libunwind-ia64(3), unw_get_proc_name(3)) have fnc name + (3). What means (3)?


How to evaluate this limit with Sandwich Theorem

Here it is the limit \begin{align*} \lim_{n\rightarrow\infty}\prod_{k=1}^{n}\left(1 + \frac{k}{n^{2}}\right) \end{align*}  I have proved that it is smaller than the square root of $e$


What is a subnet mask, and the difference between a subnet mask of 255.255.255.0 and 255.0.0.0?

My DSL/WiFi router provided by my ISP has an internal IP address of 10.0.0.138, the addresses provided by DHCP are in the format of 10.0.0.xxx.  Now, I want to start using static IP addresses on my local network, and I don't know what to provide for the subnet mask.  What is a subnet mask?  Should I be using 255.255.255.0 or 255.0.0.0 as my subnet mask? What is the difference?


Okay, so when I downloaded Ubuntu I deleted Windows XP because of activation issues. So there's nothing running side-by-side, its JUST Ubuntu. But anyhow, I want to play the games I had on my other OS on this one. For example, games like Sims 2, Hitman Absolution, etc. They read that they're in the ROM, but don't start up the install. So is there some special dealieo I need to download before they install due to the games being made for Windows or Mac? Basically, how do I install and play games on Ubuntu that I had on Windows XP? Thanks y'all.


Capitals in research areas and names of theories etc in mathematics?

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


Tell me I can't award the bounty before the warning:

This    appears before this    Please can the order be changed, so I don't get the popup before the notice.


Finite sigma-additive measure is of bounded variation

I came across a proposition, which doesn't seem obvious, but I'm curious about whether it is actually true:   Proposition:  If $\mu$ is a  sigma-additive signed measure (i.e. set function) which is finite, then it is of bounded variation.


Equirectangular sky texture in Blender Internal?

Is it possible to use an equirectangular sky texture as a world background in Blender Internal?  I'm used to doing this in Cycles, but don't know if there's a BI equivalent:    I would like to avoid mapping the environment texture onto a UV sphere if there is a more elegant way. Thanks.


what is the difference between Device driver and kernel module

i know that driver is a software that can communicate with the hardware in order to control the device that attached to the computer.whereas kernel module is a small piece of code that can inserted into the kernel to improve the performance of the kernel. I want to ask how do the driver work together with the kernel and what is the main difference between device driver and kernel module,also how do they work?


In my career I've often encountered signals that are active low (Reset being the most common). I've even seen interfaces where all control signals are actively low.  To me, this is very unintuitive and confusing. Why is there ever a need to use actively low?  Is it merely historic or is there actual gate count / power concerns that explains it?


How come Australians refer to Aboriginal citizens as 'Aboriginal peoples', not 'Aboriginal people'

I've noticed in a lot of proceedings that Aboriginal citizens in Australia are referred to as 'Aboriginal peoples', not 'Aboriginal people' - is there any specific reason?


We recently migrated our web platform from php application to nodejs react application. Ever since we are facing a major drop in organic traffic from google search. While debugging found an issue where our site's google webcache is through below error    This error was when trying to access link - bit.ly/2upsOrO  changing the link from https to http is working i.e link bit.ly/2upT9pt is giving proper cached content.  Also weird part is changing the domain to any blah domain is giving cache content, i.e link bit.ly/2uoERpe is giving proper cached content.  Couldn't understand the issue, kindly help me debug the same, also let me know if further information is needed.


Terminal display name is changed after a Time Machine Backup restore

I recently restored a Time Machine backup. After that the display name in Terminal.app is changed. MyName@M2004J19C-Redmi9 ~ %. Why M2004J19C-Redmi9?? Terminal works properly but why MacBookPro-etc. is disappeared? How can I change that? If I go to Shell>Change Title Under "Path" I have: file://M2004J19C-Redmi9/Users/MyName


Resolve filename from a remote URL without downloading a file

I am creating a script, which should download latest version of an application from repository and deploy the app.  The main issue: there are several repositories and I need to check, which of them has most recent version.  E.g.  http://repo1/xyz/LATEST -> (redirects to) -> http://repo1/xyz/app-1.0.0.0.zip http://repo2/xyz/LATEST -> (redirects to) -> http://repo1/xyz/app-1.1.0.0.zip   So I need to iterate over available repositories and get only a filename - no need to download obsolette versions of software.


Is there any way to identify which standard object supports trigger and which not?

Some standard object does not support trigger. So when I start writing trigger and then it gives error. Is there any proper way/ documentation which I can refer to decide whether any salesforce standard object supports trigger or not?  I know we can rely on Developer Console where before writing trigger we need to select salesforce object, but I am looking for some kind of documentation which clearly gives idea about whether trigger can be written or not.


I want to prove that:     If $F$ is a free abelian group of rank $n$, then $\text{Aut}(F)$ is isomorphic to the multiplicative group of all $n\times n$ matrices over $\mathbb Z$ with $\text{det}=\pm1$.   What I have tried:  Since $F$ is a free abelian group of rank $n$ so I can write $F=\langle x_1,x_2,...,x_n\rangle$. If $\phi\in\text{Aut}(F)$ then it should map any $x_i$ to another element $x_j$ of the basis $X=\{x_1,x_2,...,x_n\}$. My idea is to map any element of $\text{Aut}(F)$ to a suitable matrix. For example when $n=2$: $$\phi_1:=\{x_1\to x_1, x_2\to x_2\}\Longrightarrow \left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right)\\ \phi_2:=\{x_1\to x_2, x_2\to x_1\}\Longrightarrow \left( \begin{array}{cc} 0 & 1 \\  1 & 0 \end{array} \right)$$  Am I on a right approach? Or there is another better way? Thanks.


How can a magnet in a magnetic field have a potential energy, when the magnetic field is not conservative?

Even though the magnetic field is a non conservative field, the potential energy of a magnetic dipole (current-carrying log or bar magnet) is defined in a magnetic field. How can this be possible? Please explain. From what I have learned from reading other answers, the magnetic field, in some cases, behaves like a conservative force field. It’s called non conservative due to its field lines forming closed loops. Its nature is not exactly defined due to it acting at right angles to the velocity of charge particle, which is different than other generally known forces, and due to the non existence of magnetic monopoles. But this didn’t exactly answer my question.


Using start and end event logs to create a table/view containing spans between the times of each log


How to check if a id is already in my array

I want to know if I can check every id in my array to check if the id is already in the array.  In my case:  I have a array called "idsVoting", which is empty when the bot starts. (its a discord bot) Now the user is using a command and his user id will be save in the array. What i tried to check was :  if(idsVoting !== message.author.id)   I was thinking this will check every id in the array, but it won't. Can someone give me an idea to use? Or would a for-loop be better / easier here?


Application windows are behind Unity launcher in Ubuntu 16.04

The programs that I open are behind the Unity launcher.    How do I solve this issue?


If I have IF condition like:  if(x == 0 || y == 4) { // ... }   then if x == 0 is true does c# checks if y == 4 while we already know the whole expression is true?


Why does probability need the Axiom of pairwise disjoint events?

I'm a beginning student of Probability and Statistics and I've been reading the book Elementary Probability for Applications by Rick Durret.  In this book, he outlines the 4 Axioms of Probability.   For any event $A$, $0 \leq P (A) \leq 1$. If $\Omega $ is the sample space then $P (\Omega) =1$. If $A$ and $B$ are disjoint, that is, the intersection $A \cap B = \emptyset$, then $$P(A\cup B) = P(A) + P(B)$$ If $A_1, A_2,\ldots$, is an infinite sequence of pairwise disjoint events (that is, $A_i\cap A_j = \emptyset$ when $i \neq j $) then  $$P\left(\bigcup_{i=1}^\infty A_i\right)=\sum_{i=1}^\infty P(A_i).$$   The book fails to explain why we need Axiom 4. I have tried searching on Wikipedia but I haven't had any luck. I don't understand how we can have a probability of disjoint infinite events. The book states that when the you have infinitely many events, the last argument breaks down and this is now a new assumption. But then the book states that we need this or else the theory of Probability becomes useless.   I was wondering if there were any intuitive examples of situations where this fourth axiom applies.   Why is it so important for probabilty theory? And why does the author state that not everyone believes we should use this axiom.


Need currency format from a number in template

I am not a Django programmer but trying to look at how I can change the output of number which is supposed to printed to the page as USD. For example: It prints "Price: 3295000" when I would like it to say "Price: $3,295,000". This is the template part:
Price: {{property.price}}
  What code can I put in the template to output this in the way that I'm looking for?


How to use json_decode a post_meta value?

I have used get_post_meta($post->ID) to get all custom fields for my post since I have many of htem. Some of them were checkbox values and var_dumping the variable gives me this  array (size=1) 0 => string 'a:3:{i:0;s:6:"ozujak";i:1;s:7:"travanj";i:2;s:7:"svibanj";}   How do I echo those values?  I have tried  var_dump(json_decode($meta['my_var'])); but it gives me null


Average delay to get a badge after completing the requirements

What is the average delay between the time that all of the conditions for the badge have been met and the user actually receiving the badge?


Mortgage company using principal payment to make advanced house payments

My mortgage payment is 1200.00. I send in the 1200.00 each month along with a additional PRINCIPAL payment of 2000.00 clearly noted on the payment book as intended as a principal payment. But each month the mortgage company takes 1200.00 away from my Principal payment and  makes the next months regular payment of 1200 in advance and then applies the other 800.00 as a principal payment.  I clearly noted that the whole additional 2000.00 is for a principal payment. They have done this repeatedly when ever my principal payment is over 1200.00.   This seems like some type of scam; anyone heard of this practice before. Thanks for any help.  When I have sent in a principal payment less the the 1200.00 then they don't do it ; seems because it is not enough to use it as a regular house payment.


understanding time complexity of a set and a map

Is the time complexity when it comes to maps AND sets the same for operations like insertion, removal, search ? I read somewhere that underlying structure is a hash table meaning that time would be constant o(1) ? is that always the case ?


$C$ Hermitian, show $\text{Tr}(C)=0 \iff \exists P,Q \text{ Hermitian s.t.} \,\, PQ-QP=iC$

Let $C$ be an $n\times n$ Hermitian matrix. Show that $$\text{Tr}(C)=0  \iff \exists P,Q \text{ Hermitian s.t.} \,\, PQ-QP=iC.$$   Ideas: The right-to-left direction I have no problem with. For the left-to-right direction, I'm going to start with the fact that $$\text{Tr}(C)=0 \implies \exists A,B \in M_n \text{ s.t. } C = AB-BA.$$  I'm having trouble showing we can choose $A,B$ Hermitian. One method would be to try to show $A,B$ must be Hermitian, but that seems too strong. Along this road...  $\text{Tr}(iC)=0$, so we can write $iC=AB-BA$. $iC$ is diagonalizable with all imaginary eigenvalues, so it is skew-Hermitian. Thus $$BA-AB=-(AB-BA)=(AB-BA)^*\\=(AB)^* - (BA)^* = B^*A^*-A^*B^*.$$  But this hasn't gotten me anywhere.


How can I unescape a string that contains &#xxx; ?   Example:  "Quelque petite scratch sur l&#233;cran"  "Quelque petite scratch sur lécran"  &#232; | è  &#233; | é


Is there a word or phrase for "when someone tells you to do something and you're going to do but they continuously tell you to do it"

There are a lot of people like this. They tell you to do something, you say OK and you're going to do it (in a short time like 10 minutes or so), but if they see that you are not doing immediately what they told you, they will continuously tell you "do it", "do it", "do it". Like, every 10 seconds, they tell you to do it and annoy you so much so you do it. Is there a word or phrase to express that in English? I only want to know a phrase for telling again and again continuously. Example: My uncle told me to bring him tea while I was reading a book. I was in the middle of a paragraph when he told me that. I told him "OK, bringing". Then I continued reading, just wanted to finish the paragraph, my uncle says again "bring the tea". And he continued to say that after every 10 seconds. I had not finished the paragraph and he said that so many times that he made me stop reading and bring him tea. Is there a word or phrase for that?


Calculating the determinant gives $(a^2+b^2+c^2+d^2)^2$?

I need to calculate the following determinant in order to prove the following equality:  $$\det\begin{pmatrix} a & b & c & d \\ -b & a & -d & c \\ -c & d & a & -b \\ -d & -c & b & a \end{pmatrix} = (a^2+b^2+c^2+d^2)^2.$$  I tried using Gauss-algorithm to get an easier matrix, but I'm not sure if I did it correctly.  Calling the $4$ lines $I$, $II$, $III$ and $IV$, I did:  (1) $II \cdot a$  (2) $III \cdot a$  (3) $IV \cdot a$  After this I did:  (4) $II' + I \cdot b$  (5) $III' + I \cdot c$  (6) $IV' + I \cdot d$  So finally I got the following matrix:  $$\begin{pmatrix} a & b & c & d \\ 0 & a^2+b^2 & bc-ad & ac+bd \\ 0 & ad+bc & a^2+c^2 & cd-ab \\ 0 & bd-ac & ab-cd & a^2+d^2 \end{pmatrix}.$$  I thought this would make the determinant a bit easier, unfortunately I must have done something wrong. Is multiplication with single lines allowed as I have done it?  Thank you very much.


Native MATLAB function for sequential evaluation of functions?

So I was trying to polish my input validation in MATLAB functions and in the process I ended up creating the following function that really makes my code cleaner. I put it here in full in case someone finds it useful:  function [] = callFunctions(varargin) %callFunctions Calls a sequence of functions on their respective arguments. %   The inputs are expected as funcHdl1, {input1}, funcHdl2, {input2}, ... %   Then callFunctions calls sequentially func1(input1); func2(input2); ...  %% === INPUT VALIDATION ===  % Check that the callFunctions has at least one argument message = 'The number of arguments must be positive.'; assert(nargin > 0, message);  % Check that the callFunctions has an even number of arguments message = 'The number of arguments must be even.'; assert(mod(nargin,2)==0,message);  % Name the handles numHandles = nargin/2; handleNames = cell(1,numHandles); inputNames = cell(1,numHandles); for k=1:numHandles     handleNames{k} = 'handle';     handleNames{k} = cat(2, handleNames{k}, int2str(k));     inputNames{k} = 'input';     inputNames{k} = cat(2, inputNames{k}, int2str(k)); end  % Function to check that the inputs are function handles isValidFunctionHdl = @(x) validateattributes(x, {'function_handle'}, {});  % Create an input parser p = inputParser; % Add all arguments to check if they are handles. Don't check the inputs. for k=1:numHandles     p.addOptional(handleNames{k}, 0, isValidFunctionHdl);     p.addOptional(inputNames{k}, 0); end % Parse the input p.parse(varargin{:});   %% === PROGRAM ===  % Evaluate all the functions on their inputs for k=1:numHandles     feval(varargin{2*k-1},varargin{2*k}{:});  end  end   Now the last part called %% === PROGRAM === is the important part. It just evaluates the functions func1, func2, func3, ... on their respective inputs input1, input2, input3, ..., all of which are given as inputs to callFunctions. It is called as:  callFunctions(funcHdl1, {input1}, funcHdl2, {input2}, ...)   My question is simple: is there a native MATLAB function that does what callFunctions does? I use this during input validation (in combination with assert and validateattributes). So Ì intend to use callFunctions in nearly every function I write. I'd like to use the least custom functions possible for this.  Ben  EDIT: I didn't want to go into this to keep the post short. But yes there is a context where this seems necessary for me. This is when I do input validation with the input parser. I often need to check multiple conditions, like this (completely made up example):  % Made up function to illustrate context function [] = myFunction(input)  % Create an input parser p = inputParser; % Create functions to validate input. Must be a 2d logical array with at least one false value isValidArray = @(x) validateattributes(x, {'logical'}, {'2d'}); hasAtLeastOneFalse = @(x) assert(length(find(x)) < length(x), 'Must be at least one false.'); isValidInput = @(x) callFunctions( isValidArray, {x}, hasAtLeastOneFalse, {x} ); % Add the required input p.addRequired('input', isValidInput); % Parse the input p.parse(input);  end   This makes my code much cleaner because it allows me to combine multiple validateattributes and assert statements in the call to addRequired.


Cannot insert when word contains single quotes

I want to add single quotes word like "Dwi'q" and "Jum'at" in PHP MYSQL, but I cant add that word, I try search anything but I dont found it.  my query is:  $query=mysql_query("INSERT INTO `pln`(`ppno`,`persno`,`pernum`,`psgrup`,`lv`,`pos`,`nppsimkp`,`persub`,`busrea`,`pdthr`,`gk`,`marstakey`,`bkey`,`bakun`,`numtd`,`email`,`bdate`) VALUES ('".$ppno."','".$persno."','".$pernum."','".$psgrup."','".$lv."','".$pos."','".$nppsimkp."','".$persub."','".$busrea."','".$pdthr."','".$gk."','".$marstakey."','".$bkey."','".$bakun."','".$numtd."','".$email."','".$bdate."')") or die(mysql_error());   Thanks for help.


Why the determinant of even-sized magic matrices are zero? Anything special?

The determinant of even-magic square matrix is 0.   For example, this 4x4 magic square matrix:  {{16, 2, 3, 13},   {5, 11, 10, 8},  {9, 7, 6, 12},  {4, 14, 15, 1}}   And this 6x6 matrix:     {{35, 1, 6, 26, 19, 24},      {30, 5, 7, 21, 23, 25},      {31, 9, 2, 22, 27, 20},     {8, 28, 33, 17, 10, 15},      {3, 32, 34, 12, 14, 16},      {4, 36, 29, 13, 18, 11}}   So is true for 8x8,10x10...  Is there anything special here? Is it possible to recognize this kind of matrix and conclude that its determinant is zero?  Reference for magic square matrix:


How to iterate through a module's functions

I have this function call after importing foo.py. Foo has several methods that I need to call e.g. foo.paint, foo.draw:  import foo  code  if foo:     getattr(foo, 'paint')()   I need to use a while loop to call and iterate through all the functions foo.paint, foo.draw etc. How do i go about it?


Does "minor revision" mean "accepted with minor revision"?

I just received a decision letter from a journal editor (after three rounds of major revision). The letter shows that the reviewers "have asked for some other minor revisions". After getting the minor revision letter, I immediately completed the revision in accordance with the feedback from the reviewers (the suggested changes just involve adding a few sentences) and immediately resubmitted the revision to ScholarOne. A week has passed since I submitted the revision, but the status in ScholarOne remains unchanged. Is this normal? Can I assume that this basically means "acceptance with minor revision"? Thanks for your insight and sharing.


If I write an app for iOS and it's accepted by the AppStore, how do I know if the app is actually the app I compiled and has not being substituted/altered by, say, a "Man in the middle" style interception/attack? Is there a way to do a checksum either after the fact or from inside the app itself?


How do I use the epsilon N definition to prove this?

I must use the $\epsilon-N$ definition to prove $$\lim_{n\to\infty}\dfrac{a_1+a_2 \hspace{3px}+\hspace{3px}...\hspace{3px}+\hspace{3px}a_n}{n} = L$$ when $\displaystyle \lim_{n\to \infty} a_n = L$. Does anybody have any pointers as to how to start this problem? I'm stumped.


Prove that $\sum_{i=1}^k i!$ can never be of the form $n^m$ (where $n,m\in\mathbb N$ and $m\ge 2$) for $k\ge 4$.

I have proved that for $k\ge 4$ the sum $$\sum_{i=1}^k i!$$ can never be a perfect square i.e., of the form $n^2\, (m=2).$ But am struggling with the generalisation i.e., with the form $n^m$. Is the statement valid? I found this question on quora and no one has answered it.. Please suggest something... Thanks in advance.


How does one 'vote' for a release codename?

So I know there are questions similar to this but they don't answer this question of where can i go and vote for a codename and/or suggest one. So, does anybody know an actual url with which I can accomplish this?


I am attempting to set a value in a textarea field using jquery with the following code:  $("textarea#ExampleMessage").attr("value", result.exampleMessage);   The issue is, once this code executes, it is not altering the text in the textarea?  However when performing an alert($("textarea#ExampleMessage").attr("value")) the newly set value is returned?


Why pay for specialist studio photography lighting aka strobes when you can use continuous light sources which are more powerful and cheaper?

I am new to strobes (studio lighting) in photography. I love the idea of blowing out the background, or making the image very emotive, with a dark black background for sports portraits.  However I am not sure what are the advantages of buying studio lighting specifically for photography over just high powered (very bright) lighting which you can buy from any light store or camping store?  I get that with studio lights you can attach wireless triggers and make the lights go off only when you click the shutter button, but other than that power/money/function wise what am I missing which makes strobes worth the money?  The only factors I can see are branding build quality, and maybe the ability /flexibility to use a wireless trigger (I have yong nuo Y622 C) over a cable when connecting your camera to your studio lighting (strobes)?  And obviously you would pay more for both the build quality and added functionality in the ways you can trigger the lights.  The only downside though that I can see to just using high powered lamps is the fact you wouldn't be able to control the light, only turning it on when you click the shutter button. Instead it would be always on or always off. (since there seems to be no standard for measuring light, specialy across disciplines, e.g. photography >> watt seconds?, cycling >> luminosity, building houses >> watts)  Other than that detractor there must be something I am missing on this topic. For photography lighting I would have though the higher the power or watt sec the better (it can light up more of a scene, and still work really well at night).


I have omega 4 installed as my sub-theme, in which i have a custom layout. Now i am trying to make my home page custom, for which i have defined page--front.tpl.php in my templates/system folder, but its not working. I did explored the drupal questions/answers but nothing worked for me. I also tried to add  $variables['theme_hook_suggestions'] = array('page__front');   But it doesn't seems to be working either. How do i make it work, please help??


New to Ubuntu. Can't connect to Wifi, only ethernet

New to Ubuntu.  Trying to connect to wifi, can only connect on ethernet.  Saw this post  which introduced me to this script download  wget -N -t 5 -T 10 https://github.com/UbuntuForums/wireless-info/raw/master/wireless-info &&   chmod +x wireless-info &&   ./wireless-info   and told me to post outputs to here.  What do I need to do to fix this? Pastebin output:


Mysql - Access denied for user 'root'@'x.x.x.x'

I am trying to connect to a remote mysql database from my local box. Initially I was not even able to hit the mysql db. But after commenting the binding_address in the my.cnf file and restarting the mysql server, I am now able to hit it.  But now, I am getting an Access denied error  mysql -u root -h x.x.x.x -p Enter password: ERROR 1045 (28000): Access denied for user 'root'@'x.x.x.x' (using password: YES)   Is my IP being blacklisted or something? I can change that since I have admin permission on the remote box. Somebody help me.


Copy from Evernote to Paste to Wordpress preserving formating

Is it possible to post texts directly from the Windows desktop Evernote application to Wordpress, and retain the formating? Simple copy/past leads to format break.


In 1960, Kervaire found the first example of a PL-manifold which does not admit a smooth structure. Since then, I understand that there are many examples of non-smoothable manifolds that can be built. My question is: Which is the "easiest" non-smoothable manifold? Easiest in the sense that among all the non-smoothable manifolds, this manifold has the easiest construction process.  Thanks everyone for your help !!  Cheers...


A body in free fall "feels" no gravitational force (equivalence). Why does it continue to accelerate. Why is your program refusing my question?


Change current directory and view available directories

This isnt a duplicate, as the original answer did not help into implementing it into my raw input command interpreter. Credit to original question/answer where due.  So I'm working on a DOS style Operating System in python and I was wondering how or even if it is possible to execute a command that would let me switch between directories like a regular command prompt would let you do.   Im not sure how well I'm explaining myself but basically I would have the same command as cd in terminal so I could read files imbedded in folders, change between folders etc. I don't need any sort of limit on how complex it is but i would prefer if it isn't too long.  I have yet to find a clear solution to this. in a best case scenario, this is all you would need to input  cd folder1 cd folderinfolder1   this would be inputted into a raw input or a input and then executed so im assuming it would require splits so it knows that before the space there is cd and after the space there is the filename, such as folder I am also have an issue with using os.listdir only showing files, and not any folders.   it would be used like this  directory=raw_input("enter cd followed with a directory")    This might be a bit much to ask, not even sure if it is possible


Is there a way to reach a `protected` member of another object from a derived type?

class MyBase {     protected object PropertyOfBase { get; set; } }  class MyType : MyBase {     void MyMethod(MyBase parameter)     {         // I am looking for:         object p = parameter.PropertyOfBase;  // error CS1540: Cannot access protected member 'MyBase.PropertyOfBase' via a qualifier of type 'MyBase'; the qualifier must be of type 'MyType' (or derived from it)     } }   Is there a way to get a protected property of a parameter of a type from an extending type without reflection? Since the extending class knows of the property through its base type, it would make sense if possible.


Why is there no flag link in the LQP queue?

, for example, should certainly be flagged for spam. But to do so, I have to click the question title below and find the answer. Why can't there be a Flag button next to the Recommend Deletion button?


chocolatey - is it safe to delete the hidden .chocolatey folder in Windows 10

I'm not sure if it's okay to remove this folder located here C:\ProgramData\chocolatey  This is not related to  as this did not solve the issue.    Is there a built-in choco command to purge old uninstalled programs.  Nothing in the docs or running the command choco -? leads to believe there's nothing natively to do so.  Here are the contents of my chocolatey folder.  `  Then when I run the command choco outdated I get the response Chocolatey has determined 0 package(s) are outdated.  Yet these 3 programs are no longer install, yet remnants of them apps remain.  They were all uninstalled via the choco uninstall app-name command.


Prove if metric space $X$ contains a connected dense subset, then $X$ is connected.

I am attempting to solve the following question.     Q. Suppose a metric space $X$ contains a connected dense subset $A$. Show that $X$ is connected.   Here is my attempt at a solution:     A. Assume to the contrary that $X$ is not connected, that is, let $X=U \cup V$ where $U$ and $V$ are two disjoint, non-empty, open sets.  Since $A$ is dense, we have that $cl(A)=U \cup V$ and since $X$ is a metric space, then $A \subseteq U \cup V$...   This is where I get stuck. I'd like to show that $A$ is not dense, but I'm not really sure where to go from here.  Any help would be appreciated!


Is it possible to add / inform clearly new users that the first minutes after they post a question they get 60-90 percent of the brain power people have to offer?  Most often, people post and go away for 1, 2 hours...


Is there any way to open program which is running in background. I've developed an application in java for ubuntu and want to open that application through its pid if it is already being running just like skype, skype is not create new instance if it is already running whethere clicks from the launcher(menu) insted of new instance it reopen same process.


I am from Brazil and travel a lot in Schengen countries. Under the rules of Schengen visa (3 months stay in a 6 months period). In my passport are the entrance and exit stamps, also to chec the days I stay in Schengen.  I need a new passport and will get this in Brazil. So in this new passport are NOT the stamps. Does this mean I start new with the Schengen visa rule? I seems like. The new passport is empty. Or do I miss something? It would be great because I am almost on my 90 days stay in the period of 180 days.


This question doesn't specifically pertain to R, but I   chose to use R to illustrate it.  Consider the code for producing confidence bands round a (normal) qq-line:  library(car) library(MASS) b0<-lm(deaths~.,data=road) qqPlot(b0$resid,pch=16,line="robust")   I'm looking for an explanation of (or alternative a link to a paper/online document explaining) how these confidence bands are constructed (I have  seen a reference to Fox 2002 in the help files of R  but sadly I don't have this book handy).   My question will be made more precise with an example.  Here's how R computes these particular CI's (I've  shortened/simplified the code used in car::qqPlot)  x<-b0$resid good<-!is.na(x) ord<-order(x[good]) ord.x<-x[good][ord] n<-length(ord.x) P<-ppoints(n) z<-qnorm(P) plot(z,ord.x,type="n") coef<-coef(rlm(ord.x~z)) a<-coef[1] b<-coef[2] abline(a,b,col="red",lwd=2) conf<-0.95 zz<-qnorm(1-(1-conf)/2) SE<-(b/dnorm(z))*sqrt(P*(1-P)/n)     #[WHY?] fit.value<-a+b*z upper<-fit.value+zz*SE lower<-fit.value-zz*SE lines(z,upper,lty=2,lwd=2,col="red") lines(z,lower,lty=2,lwd=2,col="red")   The question is: what is the justification for  the formula used to compute these SE (e.g. the line SE<-(b/dnorm(z))*sqrt(P*(1-P)/n)).   FWIW this formula is very different from the formula of the usual


How to indent long code in question or answer?

Suppose I had to post 400 lines of code then will I have to indent all those lines by four spaces one by one or is there any other way ?


I no longer have privilege to comment (while reviewing)?

So, I was reviewing the Low Quality Posts review queue, when this item popped up in front of me:   I went down the page to see if the question was copied from a comment or something; and I found myself getting the following statement:     add comment (requires )      I understand it might(?) be because I was in a review queue and all, but I think either it should show     No comments allowed in review queues   or, pop-up a blue coloured modal (I don't remember what it is referred to as, exactly) with message similar to above one, instead of outright denying me the privilege to comment.


The integration formula of $\int \sin^n{x}\cos^{m}{x}\ dx$.

I am in war with my textbook. It says that $\int \sin^n{x}\cos^m{x}\ dx=\frac{\sin^{n+1}x\cos^{m-1}x}{n+m}+\frac{m-1}{n+m}\int \sin{x}\cos^{m-2}\ dx$.  Then I wrote the proof. Here is what I got. \begin{equation*} \begin{split} \int \sin^n{x}\cos^m{x}\ dx&=\int \sin^n{x}\cos^{m-1}{x}\cos{x}\ dx\\ &=\int \sin^{n}{x}\cos^{m-1}\ d(\sin{x})\\ &=\cos^{m-1}x\frac{\sin^{n+1}{x}}{n+1}-\int \frac{\sin^{n+1}{x}}{n+1}(m-1)\cos^{m-2}{x}\ dx\\ &=\frac{\sin^{n+1}{x}\cos^{m-1}{x}}{n+1}-\frac{m-1}{n+1}\int\sin^{n+1}{x}\cos^{m-2}{x}\ dx \end{split} \end{equation*}  Maybe you know what I missed?


Why do delimited files always ask to save after I already have?

I'll hit save on a comma and/or tab delimited file - Prompt: "Do you want to keep using this format?" Me: "Yes."  Then when closing the window and without making any changes, a prompt asks me, "Do you want to save?".... "Do you want to keep using this format?" Whether one hits yes or no here, the file will open just as it was saved a moment before.  Anyone know why this is and if there's a config to make it stop?


Making Commas appear at the top instead of bottom

How would one make a symbol, say \circ in a symbol separated set of letters i.e. A_{\circ} B appear at the top between the letters i.e. A^{\circ} B, but to an arbitrary height (not just using _ or ^)?  Thanks.


What happens when a bounty question has no good answer.?

I asked a question on SO, and there was only one answer given to that. I could not understand that and hence I decided to give it a bounty. Now its 4 days since bounty and I have not received any new answers. The old answer is nether accepted nor having votes. And I don't want to award bounty to that. Now how and who will get the bounty if no new answers come after the bounty ends.?


I'm kinda new to Ubuntu.  I have 2 operating systems, Windows 7 on partition C and Ubuntu 14 on partition D. I need to reinstall Windows, wiping only partition C (I need to preserve all files on D). I don't have an installation disc or USB for Windows, only an .iso image. Is it possible to reinstall Windows with this? How can it be done?


When I want to use sudo in Terminal I get this error: E: Type 'sudo' is not known on line 2 in source list /etc/apt/sources.list.d/mono-official-stable.list E: The list of sources could not be read. E: Type 'sudo' is not known on line 2 in source list /etc/apt/sources.list.d/mono-official-stable.list E: The list of sources could not be read  I know cause of this problem is Mono and I tried to delete it but I couldn't


parseInt returning values that differs by 1

I have data like this:  var currentValue="12345678901234561";   and I'm trying to parse it:  var number = parseInt(currentValue, 10) || 0;   and my result is:  number = 12345678901234560   now lets try:  currentValue="12345678901234567"   in this case parseInt(currentValue,10) will result in 12345678901234568  Can anyone explain me why parseInt is adding/substracting 1 from values provided by me?


C# .NET: How to check if we're running on battery?

i want to be a good developer citizen, , and disable things if we're running over Remote Desktop, or running on battery.  If we're running over remote desktop (or equivalently in a Terminal server session), we must disable animations and double-buffering. You can check this with:  /// <summary> /// Indicates if we're running in a remote desktop session. /// If we are, then you MUST disable animations and double buffering i.e. Pay your taxes! ///  /// </summary> /// <returns></returns> public static Boolean IsRemoteSession {     //This is just a friendly wrapper around the built-in way     get     {         return System.Windows.Forms.SystemInformation.TerminalServerSession;     } }   Now i need to find out if the user is running on battery power. If they are, i don't want to blow through their battery. i want to do things such as   disable animations disable background spell-checking disable background printing turn off gradients  use graphics.SmoothingMode = SmoothingMode.HighSpeed;  use graphics.InterpolationMode = InterpolationMode.Low; use graphics.CompositingQuality = CompositingQuality.HighSpeed; minimize hard drive access - to avoid spin up minimize network access - to save WiFi power   Is there a managed way to see if the machine is currently running on battery?  Bonus Reading    ()  ()  ()


Finding examples of infinite groups where all elements have finite order

I was trying to figure out if there could be an infinite group where all elements had finite order. I gave it a thought and then came up with the group of all integer sequences $\mod n$, which I think can be formally written as $\mathbb{Z}_n^\infty $.  After another moment of thought I realized I didn't like this example, as I just took a finite group and created sequences of elements there.  Are there any other, more satisfying examples? Or is it true that if $G $ satisfies what I am asking, then $G $ is an infinite product of finite groups?  How do these things extend to rings? Defining the product as component-wise I can still think of $\Bbb{Z}_n^\infty$.


Why must the determinant of a matrix with with integer entries be an integer?

Why must the determinant of a matrix with integer entries be an integer?   Note: I know what a determinant of a matrix is, not sure how to explain this question.  Is that because if the matrix is made with integers the determinant has to be an integer as well?


How are echo and print different in PHP?

Possible Duplicate:          Is there any major and fundamental difference between these two functions in PHP?


Let $X \sim Bin(n,p)$ show that $X/n \nsim Bin()$

Let $X \sim Bin(n,p)$   Part A.  Show that the argument      "Then $X/n \sim Bin()$ with $E[X/n]=p$and $Var[X/n]=pq/n$"    is false.   My book says we can prove this result using a moment generating function. But to me it makes no intuitive sense: We have Bin-distributed RV $X$ and if we rescale it with $1/n$ of course it will be Bin-distributed.  And we know from standard formulas that $E[aX]=aE[X]$ and $Var[aX] = a^2Var[X]$ so I think the argument is correct.   (For full disclosure, the argument we should falsify according to the book is "Let X be a binomial random variable with mean np and variance np(1−p). Show that the ratio X/n also has a binomial distribution with mean p and variance p(1−p)/n." But I think the argument is correct. )    Ok, now I get part A. Here is Part B. Prove it using the moment generating function of $X/n$.   Attempt: I get $$m_X(t)=E[\exp(tX/n)]=(m_X(t))^{1/n}$$


How is $0.9999\ldots$ equal to $1$? I researched it a bit on , and I find a lot of different ways, but I'd just like to clear upon them. Intuitive: I understand that this explanation is saying that $1$ is the highest number greater than $0.\bar{9}$, but that doesn't make sense why they are equal, for example, $0$ wouldn't be equal to $0.00000(1)$. Discussion on completeness: I honestly didn't understand what it meant, but in the next paragraph it says the previous paragraph isn't proof. Formal proof: I followed it for a while until to the $0\le 1-x\ldots$ line, then I got lost in how it was trying to prove. Algebraic arguments: I don't follow how this one works, because, say $x = 0.99$ (To simplify things, it could be $0.999$ if wanted), $10x = 9.9$ $10x = 9+0.9$ while in the argument it stated $10x = 9+0.99$ (I believe $0.99$ should be $0.9$) $10x = 9+x$ $9x = 9$ $x = 1$ Analytical Proof: This time I haven't got the faintest clue how this relates, and what it's saying. I know I didn't cover most of the arguments, and there's a lot of math concepts I haven't scratch the surface of yet, but I was just curious how this is true. I didn't understand if possible for the questions, show a summary of what it was trying to say. Lastly, I just wanted to say I have a very elementary knowledge of mathematics. I still have an extremely long journey to go, so if don't understand a lot of the complicated, or even simple concepts that may help explain the problem, please be patient.


Repetition in Stack Apps user of the month

My profile is repeated in top Stack Apps users of the month as shown in the snapshot.  Is it normal?


My teacher told me that sun is a black body but after reading at various sites whre they say that sun is not a black body but has black body radiations because it cannot absorb all radiations.


How to best represent a ToggleButton (representing on/off) with the ability to be locked

I'm designing a ToggleButton control that has the ability to be in a locked state in which user interaction will not be able to further toggle the control. In general I would like the button to appear somewhat natural in the natural scheme of rules laid out in Microsoft's UXGuide but I don't mind the idea of using some sort of custom graphic or unique concept to signify fact that the control is locked.  As far as button appearance I could use:   An iPhone style . A toggle button featuring a custom graphic icon such as a power button that lights up when activated. A plain old Check Box.   If I'm to go with a check box I could use the disabled state to represent that the control is locked however this may look to the user as if the control's setting isn't in effect since it normally appears muted via a grayed out style. For the other two options, the only reasonable thing I can think of is to overly some type of padlock style icon on or near the toggle button when it is locked.  If somebody can lead me in the right direction it would be greatly appreciated.  Proposal#1: Below is a concept that I came up with that I think looks somewhat similar to the iPhone toggle but which was inspired by the . Also I incorporated the suggestion by Hisham to only show the padlock icon when in a locked state. This concept is more specific to toggle button that represnts on/off states but for that purpose I think it appears quite adequate.    Proposal#2: This is another take on the example above but uses the ubiquitous power icon instead of the on/off text. Additionally I used a grayed out text instead of the padlock to signify that the control is on but cannot be toggled any further. Note, I have seen some cases where the line that intersects the circle in the power symbol changes it's position depending on whether power is on or off however I cannot dig up any examples of this right now.    UPDATE: Since sometimes context is everything, I created a rough but more specific mockup to show how the toggle control I'm developing will be used. In general I would like be able to apply some of the concepts we develop here to other more common user interfaces but I figured I should at least elaborate further on what is leading more twords hardware style buttons. In the long run, whether I'm going to emulate a hardware look or not the important point is that this toggle control will be repeated in many places and will serve an identical purpose thus perhaps in some cases a specialized toggle control like the one I've proposed would be a good solution otherwise in some cases perhaps a more traditional UI one could use two radio buttons for the ON and OFF states and then use a label to explain or just disable these controls when they are to be in a locked state.    From this example one can see why I'm also moving away from the padlock metaphor as well since placing a padlock icon on the on/off toggle button may mislead the user into thinking the whole control is locked which would not be the case. The locked/disabled state is only supposed to affect the ability to switch the effect control on/off.  Some related links:


"Toward" or "towards" – what would a native speaker use?

In  we learn that toward and towards are interchangeable, but that the former is somewhat more typical of U.S. English and the latter of British English, although there is some indication that this does not always hold true.  But how about actual use? Being a non-native speaker, I cannot completely trust my intuition about what "sounds right". Is it true that toward sounds more formal than towards to a native English speaker? Does it vary between different variants of English? Should I use one in academic text and the other in casual communication? What are the nuances? In summary, how should I choose which one to use if I want to be consistent in my writing style? I'm looking for intuition for different kinds of situations.


Cant get opera to use flash on Linux mint ulyssa 20.1

I want to use opera but cant get it to display video. How do I get it to allow flash.Can I download flash to get it to work or do I need to do something else.


I Have a Samsung Tab 3 8" Galaxy, which uses an "Exynos Dual-core Processor. Is there going to be a suitable version of Ubuntu for it?


Determine all continuous real function which satisfies the following

We are required to determine all continuous real valued functions $f$ such that $$f(f(x))=-x$$  I’ve determined that if such a function exists, it must be bijective. But I don’t know if such a function exists, let alone find all such functions. Any hints and suggestions will be appreciated.


Stand-By Flights, Regardless of Destination?

I've started seeing commercials for some company doing a kind of "travel roulette" where a traveler is randomly given a destination and their vacation is free if they agree to go right now.  Which is pretty cool, but the idea got me thinking...  If someone were to set up a general time slot (say, 2 weeks) and just show up at the airport  (US in this case) with only a carry-on bag, is there some way to sort of hang around in a stand-by status and pick up a last-minute stand-by flight really cheap?  Basically, not caring about where to go, just wanting to go on some sort of travel "adventure" somewhere in the world?  (That is, this is specifically asking about international flights.)  I feel like that used to be possible back in the day, but I don't know much about the rules and regulations these days in US airports aside from just shuffling through like any other traveler.  For example, one used to be able to get to the gates without a boarding pass (which I imagine would be the ideal place to grab a last-minute "the doors are closing now and there are still empty seats" ticket), but that's no longer the case.  For anybody who happens to work in or know about the workings of airline travel, is this something that's possible?  It occurs to me that, at that last moment when the plane is boarding, any empty seat is essentially lost revenue.  So I would think that there should be some way to get into one of those seats at cost plus a moderate fee.  Or is this just wishful thinking?  Even if it is possible, is it not worth it because getting back home would be cost-prohibitive?


How to compute and interpret the confidence interval on a QQ plot

I often see QQ-plots with a confidence interval:    For my application, I have a QQ plot of test p-values against a uniform distribution. I want to add the 95% CI of the observed p-values on the plot, but I don't know how to compute them.  In other words, I am not sure:   That I correctly understand what the CI represents on QQ plots. How they are computed.


Google results for sponsee have scattered definitions in unreliable sources, so it does not appear that is a real word. I'm looking for something similar, a single word.  The specific context is a social group membership application where new members must be sponsored (as in definition 2, here - "one who assumes responsibility for some other person or thing") by existing members. I am looking for a single word to describe the target of such a sponsorship. I am about to sponsor a fraternity, but I would like to have a more general word for what I'm sponsoring. Next time, the fraternity could well be a study club, or something else.  Therefore, what is the sponsored party also called? E.g. if I sponsor somebody, that person is my __?


What can be said about $\sum a_n^{\frac{n-1}{n}} $?

If $a_n$ are positive real numbers such that $$ \sum a_n$$ converges, what can be said about $$\sum a_n^{\frac{n-1}{n}} ?$$     To see how the land lies let's test a few standard cases.    If we have a converging geometric series $a_n=aq^n, 0<q<1$, $a>0$, then for all $n\ge1$ $$a_n^{(n-1)/n}=a^{(n-1)/n}q^{n-1}\le Aq^{n-1}$$ with $A=\max\{1,a\}$. Meaning that the new series is majorized by a converging geometric series. If $a_n=1/n^{1+\epsilon}$ for some $\epsilon>0$, another standard converging test series, then, for $n>2/\epsilon$, we have $(n-1)/n>1-\dfrac\epsilon2$, and consequently $$a_n^{(n-1)/n}<\frac1{n^{(1+\epsilon)(1-\epsilon/2)}}.$$ Meaning that we have again a converging majorant as the exponent is a constant $>1$.   But what happens in general?


How do I get Serena to follow me after I completed the dawnguard quest line?

I completed the dawnguard quest line and after killing Harkon I asked Serena to make me a vampire so I could travel back the soul cairn and get valerica to come back to tamriel. Than I cured myself of being a vampire and I got Serena to do the same. A few days later she came back to the dawnguard castle and after telling me she was now a human, I was not able to start a conversation with her. She would only say "yes?" Or "what do you need?" And that was it.


How can I complete the prerequisites for Masters in Computer Science on my own?

My Background: I am an EE graduate, working in a Software Company from last 2+ years as an Application Developer(Java & J2EE). Recently I started thinking of going back to college and do my Master's in CS, as most of the jobs in industry require a degree in CS.  Country of Residence: India  Countries of Interest for University Applications: US, UK, Australia and EU.  I have noticed that there are prerequisites to get admitted to those programs. Specifically, I need to have completed courses in Data Structures, Algorithms, Operating Systems, Theory of Computation, Compilers and Computer Networks. My undergraduate degree did have courses like Computer Networks, but nothing else.   In some other Universities, I can get admitted to MS in CS, but then I need to complete those courses at the College before starting graduate school coursework. I understand all of those things, as I took various Computer Science Courses online. I understand all the things that there are in undergraduate Computer Science Course. So here are my options:-  1) Take a post-bacc Course in computer science. (That Costs a lot in money and Time)  2) Do Nothing and apply without requirements being completed and let them decide whether or not I should enroll in UG CS courses at college.  3) Do some online Computer Science courses on edX, Coursera and show them that.  Which one of them is more favourable to a person working in Software Industry with an EE background?


After some updates a few months ago I get these outputs:  W: Erro GPG: http://sft.if.usp.br trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32 W: Erro GPG: https://download.01.org trusty InRelease: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY A902DDA375E52366 W: Erro GPG: http://extras.ubuntu.com trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 16126D3A3E5C1192 W: Erro GPG: http://sft.if.usp.br trusty-updates Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32 W: Erro GPG: http://archive.canonical.com trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32 W: Erro GPG: http://sft.if.usp.br trusty-backports Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32 W: Erro GPG: http://archive.canonical.com trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32 W: Erro GPG: http://sft.if.usp.br trusty-security Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32 W: Erro GPG: http://ppa.launchpad.net trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY C71839136CF5CE97 W: Erro GPG: http://ppa.launchpad.net trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 90BD7EACED8E640A W: Erro GPG: http://ppa.launchpad.net trusty Release: As assinaturas a seguir não puderam ser verificadas devido à chave pública não estar disponível: NO_PUBKEY 9641080A705C2B92   I know how to fix this ordinarily, but this time I'm getting too many. Except for the first one (about intel graphics) the others seems to be related to Ubuntu itself. I have tried changing mirrors but I'm stuck with the same error.  Update : sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com  returns this error and many similar:  gpg: recurso do bloco de chaves: `/etc/apt/trusted.gpg.d/tuxpoldo-btsync.gpg': limite de recurso   I suppose that's "resource limit"  `


For an incident photon to be absorbed by a material, must it exactly equal a difference in the electron energy levels, or does it just have to be more than one such difference.  If more is okay, what happens to the remaining photon energy?  Does it continue on as a lower energy photon, if so, the remnant photon might not have enough energy to be absorbed.  Would it just continue to travel onward through the material indefinitely?  Can one or more electrons be knocked off by a single photon?  The  concepts of exact energy levels sounds a bit unnatural, like perfect sine wave.  Are there uncertainty bands in these electron energy levels?


I tried this example in $S_3$ and saw that this held but I couldn't figure out how to prove it for all $S_n$. Any help would be appreciated.


I am trying to type a matrix, but the parentheses looks bigger. How can I make the parentheses fit?  It looks like the problem is caused by the doublespacing, but I want the double spacing for the text. How can I get around this?  Below is the code:  \documentclass{article} \usepackage{amsmath} \usepackage[doublespacing]{setspace} \begin{document} \begin{equation} \rho= \begin{pmatrix} \rho_{00} & \rho_{01}\\ \rho_{10} & \rho_{11} \end{pmatrix} \end{equation}  \end{document}   Here is the image:


why do we use dy/dx as ratio though it is not while solving the problems of integration by substitution

According to my knowledge dy/dx is not a ratio. Then while solving the problems of integration by substitution how can we use it as ratio. Because of we have dx/dt =f(x). Then while shoving it by substitution why do we take it as dx=dt•f(x).


I'm just a newbie in Linux and recently got a VPS (Ubuntu 14.04 LTS Server). How can I secure its ssh server from brute-force attacks?


Some answers contain characters that look like keyboard keys. They look like      Ctrl + E   What markup do I need to add to make Ctrl and E look like actual keys? That's not mentioned in the formatting help.


Postfix sometimes fails to forward accepted mail

I have postfix on my box. All it should do is accepting all email and forwarding it somewhere else. I did it like so: main.cf: # (default config) virtual_alias_domains = domain.one domain.two virtual_alias_maps = regexp:/etc/postfix/virtual  virtual: /^admin@/ mail.one@example.org /^webmaster@/ mail.one@example.org /^security@/ mail.one@example.org  /@soptik.tech$/ mail.one@example.org /@prenoc.cz$/ mail.two@example.org  This works most of the time. But sometimes, the email gets undelivered. For example, I just donated to mozilla when I saw they had to lay off third of they workforce. But instead of an email, I received this: /var/log/mail.log (this seems to be most relevant line) Aug 11 20:38:59 junko postfix/smtp[13518]: 3D8A93F57B: to=<mail.one@example.org>, orig_to=<me@domain.one>, relay=mx1.seznam.cz[77.75.78.42]:25, delay=1.6, delays=0.43/0.01/1.1/0.16, dsn=5.7.1, status=bounced (host mx1.seznam.cz[77.75.78.42] said: 550 5.7.1 Sender Policy Framework of `bounce.e.mozilla.org' domain denied your IP address. (in reply to MAIL FROM command))  Why does it fail because of Sender Policy Framework? Forwarding works for almost all normal mails and lot of spam, but it seems to not work for Mozilla. I would thought that this will either work for everything, or nothing. Is there an issue with my configuration, or does the server I forward my mail to just failed to verify mozilla email? If so, can I, together with forwarding the mail, save it locally as well, just to be sure? Thanks.


Prove a function attains each complex value.

Let $p$ and $q$ be non constant polynomials. Prove that the function $f(z) =p(z) e^{q(z)} $ attains every complex value.   I tried to use the little picard but i cant solve it.  I assumed that there exists $w_0$ complex that $f$ does not attain. Then i wrote $p(z) =\frac{f(z)} {e^{q(z)}} $. The problem is that the argument that since $f$ ommits $w_0$ and the denominator ommits the value one does not imply that the polynomial $p$ommits also the same value hence a contradiction. Could you help me?


Further questions on hatcheck problem: what is the probability of r people receiving the correct hat?

Since the original hatcheck problem is really famous and many questions have been posted on the forum, I think I can safely skip the context part. Note that, the probability of exactly one man receives the correct hat is 1/n, this can be solved by using the linearity of expectations. Moreover, no man receives correct hat is a derangement, which can be solved by inclusion-exclusion principle. Now, to take a step further, if we are to calculate the probability of exactly r man receives the correct hat, how can we exploit the information we have already have to derive a simpler answer? Since all the materials online seems to be particularly interested in the above two cases, I feel rather confused.


I have tried everything to adjust and fix the sensors on my garage door. They will not close when the sun is hitting them. Can I just remove them?


What are the best practices, or guidelines, to having a web form auto-save and manually save?

There are many ways in which a web form is made to auto-save and manually save; I'm wondering what would be the best practices to do so.  Form is a web application form, and I want to save user values for the purpose of tracking progress and not losing their work if they take a break or want to resume working on it later. I want them to also be able to click the save button manually. I want them to be able to click a "submit" button to mark it as submitted and asynchronously send it to the database, once all the saves have validated that the form is completed successfully.  Here are some of my concerns (some are technical and others are not):   How often should I auto-save the form? 30 seconds? A minute? More? Less? What determines the best interval to save? Should I save onBlur of every form element, or should I do it onFocusOut at the form? How do I save while user is still filling out a textArea without leaving the focus, yet? How do Gmail and StackExchange do it? I've read that , but when should I asynchronously submit it to the database as opposed to keep it local? What if the user leaves the locally saved form and it still hasn't been submitted to the database? What's the best failsafe for crashing? When should I notify the user that the form is saved like when Gmail does it? Is it bad practice to also include a save button in addition to having a auto-save feature? Should anything change when filling out the form on mobile as opposed to desktop? Is it possible to make the form 100% capable of not losing progress, or is the user bound to lose some data at some point?   Anything else I should be aware of, keep into consideration, or try to implement in order to make the experience more convenient for the user?  If there are any good sources other than  and  for me to read on, please let me know.


I am a graduate student of math right now but I was not able to get a topology subject in my undergrad... I just would like to know if you guys know the best one..


What is the meaning of (sudo)?.I looked for the meaning, but I could not find it.


Let $a,b$ and $c$ be vectors in $\mathbb{R}^3$. How do I show that    $$\|a-b\| \le \|a-c\|+\|c-b\|$$  and   $$\|a \times b\|^2=\|a\|^2\|b\|^2-(a\cdot b)^2$$ ?


Express one set in a partition through the others

Let $S=A\cup B\cup C$, $A$, $B$ and $C$ are mutually disjoint. Clearly, $C=S-(A\cup B)=(A\cup B)^c$. How do we derive this identity? Or it's supposed to be obvious (and it is) from the fact that ${A, B, C}$ is a partition of $S$? It's used in my textbook but the author never mentioned where it came from.


It would be awesome if the top bar stays always on top, so if i scrolled down it doesn't disappear..  See  as an Example.


Aborted during 18.04 config phase, how to resume?

I am running Ubuntu 16.04 and decided today to install the 18.04 version. I followed the instructions here:  After about 30-45 minutes I get to a phase of the installation where it is asking if my previously configured dotfiles should be overwritten with fresh ones from the upgraded packages. During one of them I select to view the diff, but then cannot find out how to exit the view. ESC, q, etc. don't work, so I try Ctrl-C, which results in a complete abort of the process. I'm afraid I now have a half-baked installation going. For example, System Settings only have about 7 entries, where the old version had about 20 or so. Also the Software & Updates part of the system settings looks completely wrong. Running the command sudo do-release-upgrade results in a message that no new release is found. Is there any way to resume the configuration or re-run the installation? Edit: I have tried looking into other posts here and their solutions, but my problem is that dpkg is locked. For instance when I try sudo apt-get install -f I get:  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?  Edit 2: I came closer to what the problem really was. I restarted by mistake a found myself unable to log back in. I have a dual boot with Windows and use Grub to handle it. The standard Ubuntu option resulted in just a purple screen. Going to the Advanced options for Ubuntu, the first option resulted in the same error described here . Not sure how the boot problem arose from the aborted OS upgrade, but here we are.


Explorer.exe keeps trying to Visit Suspicious Website

Today, I have been receiving pop-ups from Malwarebytes roughly every 20 minutes telling me that it blocked C:\Windows\explorer.exe from attempting to visit appexsports.trafficmanager.net. A full scan with neither Malwarebytes nor Windows Defender does not find anything. Reading online, this issue seems to come with an array of browser hijacking issues, none of which I have experienced beyond what seems to be the hijacking of explorer.exe. Does anyone know how to remove this?


I'm working with a WPF ListBox and inside the ItemTemplate I have a StackPanel.  I'm trying to bind the width of the StackPanel to the ViewportWidth of the ListBox but I'm not able to find a way to do so.  If I bind the ActualWidth it's close, but since the vertical scrollbar is included in the ActualWidth I still end up with things hidden behind it and a horizonal scroll bar.  Please see the XAML below:  <ListBox x:Name="MessagesGrid" Grid.Column="2" HorizontalContentAlignment="Stretch"> <ListBox.ItemTemplate>     <DataTemplate>         <Grid Width="{Binding Path=ActualWidth, ElementName=MessagesGrid}" HorizontalAlignment="Stretch">             <StackPanel Name="ToMe"  HorizontalAlignment="Stretch" Visibility="{Binding IsFromMe, Converter={StaticResource BooleanToHiddenConverter}}">                 <TextBlock Text="{Binding Date}" FontSize="8" TextWrapping="Wrap" Padding="0,0,60,0"/>                 <TextBlock Text="{Binding Text}" FontSize="12" TextWrapping="Wrap" Padding="0,0,60,0"/>             </StackPanel>             <StackPanel Name="FromMe" HorizontalAlignment="Stretch" Visibility="{Binding IsFromMe, Converter={StaticResource BooleanToVisibleConverter}}">                 <TextBlock Text="{Binding Date}" HorizontalAlignment="Right" FontSize="8" TextWrapping="Wrap" Padding="60,0,0,0"/>                 <TextBlock Text="{Binding Text}" HorizontalAlignment="Right"  FontSize="12" TextWrapping="Wrap" Padding="60,0,0,0"/>             </StackPanel>         </Grid>     </DataTemplate> </ListBox.ItemTemplate> </ListBox>


Trying to make a div appear when hovering over an image

I'm trying to make a div with some information about an image appear when I hover over the image, my code doesn't seem to work.  HTML:  < div class="batmobile-info">This is Batman's batmobile, he uses it to chase his enemies or to flee from the police.< /div>  < img class="batmobile" src="images/batmobile.png" alt="batmobile" >   CSS:  .batmobile{ position:relative; width:500px; height:200px; top:350px; left:200px; }  .batmobile-info{ visibility:hidden; }  .batmobile:hover .batmobile-info{ background-color:white; text-align:center; width:290px; height:40px; position:absolute; top:500px; left:700px; visibility: visible; }


How do I set up my LaTeX document to enable me to cite from my BibTeX bibliography?

This may be an overly simplistic question but please bear with me...  I have a BibTeX bibliography containing all of my references, set up using BibDesk. I am now trying to cite these references in my LaTeX documents. Following the advice on the LaTeX wikibooks page, I have included the following lines into my LaTeX document...  \bibliographystyle{plain} \bibliography{/Users/Graeme/Documents/References/BIBliography.bib}   ... where BIBliography is my .bib file, created in BibDesk.  Unfortunately, when I cite something in the document, using \cite{citekey} and typeset the document, the log tells me that there were undefined references. In the .pdf that is produced, there is a [?] where the references should be.  Am I doing something wrong? Do I need to store my .bib for in a particular location? I know there can be some errors that mean you need to typeset the document several times, but I have tried countless times to no avail.  I would be very grateful if someone could help out.


Can motherboard support 256GB RAM if specs say max 128?

I have ASRock Z390 Taichi motherboard with 9th gen core i5-9400F. The motherboard manual says that max 128GB ram is supported with 32GB per slot. I recently saw that we now have DDR4 ram in market with 64GB per DIMM. I was wondering if the motherboard will support 4 of these, making the total to 256 GB. The reason I ask is that I have a couple of computers whose max rating is 16 GB per slot but putting in 32 GB seems to work perfectly, with all the ram showing up.


Use of "post-hoc" tests - do these require an ANOVA to be performed first?

I would like to compare multiple means using a method such as an ANOVA. This would have to be followed up with either Scheffe's test or the Games-Howell post-hoc method (my data is non-normal - to different degrees and can't all be transformed to normality using the same transformation - heteroscedastic and has greatly differing sample sizes).  In their Opthalmic and Physiological Optics paper, Armstrong et al. (2000) state that these tests can only be performed after an ANOVA returns a significant result. My question is this - how can an ANOVA be appropriately applied to data such as mine, which require these post-hoc tests simply because they violate so many assumptions of the ANOVA? It seems odd to me that they should advocate the use of an ANOVA before post-hoc tests that are used in place of others because of the violations of the ANOVA assumptions.  Also - on a side note, does anyone have any advice as to whether to use the above approach or to use the multcomp package available in R?  Many thanks!


Short scifi story about a children-only society because they killed them all

A 2nd half of 20th century story about a society with no adults except one individual. The punch line is something like “..we killed them [the adults] all”.


Why does SE have SO as stand-alone domain, and others as sub-domains?

As the title states, why does Stack Exchange (SE) have Stack Overflow (SO) its' own domain, and yet everything else is just sub-domains under SE?  Is it because SO came first, and then SE was a product of that?  Just curious...


Is there any way to boot Windows automatically if it is hibernated in Grub?  I mean is there any way to force the user to boot the hibernated Windows without any choices?


What are the different ways to set file permissions etc on gnu/linux

On Unix, a long time back, I learned about chmod: the traditional way to set permissions, on Unix (and to allow programs to gain privileges, using setuid, setgid).   I have recently discovered some newer commands, on GNU/Linux:    setfacl extends the traditional ugo:rwx bits and the t bit of chmod. setcap gives more fin-grain control than ug:s bits of chmod. chattr Allows some other controls(a bit of a mix) of the file.   Are there any others?


Optimal estimation of a single parameter given data at different scales

Let $A,B,C,D$ be independent normal random variables distributed according to $\mathcal{N}(0,\sigma^2)$ and $E = A+B+C+D$.  The goal is to provide an optimal estimate of $\sigma^2$ given samples of $A,B,E$ but not $C,D$.  In this case optimal refers to minimising the root-mean square deviation of the estimate $\hat{\sigma}^2$:  $$RMSD(\hat{\sigma}^2) = \sqrt{\mathbb{E}\left[\left(\hat{\sigma}^2-\sigma^2\right)^2\right]}$$  I can think of a simple approach to estimate $\sigma^2$ given samples of $A,B$ which is to simply compute the sample variance. Also I know that the variance of $E$ is $4\sigma^2$ so I could compute the sample variance of $E$ and divide it by 4 to get an estimate of $\sigma^2$. However it should be possible to combine the information from both $E$ and $A,B$ to improve estimation $\sigma^2$. Could you outline the approach to use both sets of information?


Properties of a set of all isomorphisms $ f: G \to G $

I'm kinda stuck with this task. Let $G$ be a group and $ S $ the set of all isomorphisms $ f: G \to G$. I first want to show that $ (S, \circ) $ is also a group. I believe I've shown that all the properties of a group is fulfilled with $ (S, \circ) $: i) Assume that $ x \in $ and $ f_1,f_2 \in S$. Then $f_2(x) = y \in G$, since $ f_1 $ is an ismorphism. $ f_2(y) = z \in G $ since $ f_2 $ is an ismorphism. Then $ f_1(f_2(x)) = f_1(y) = z = f_1 \circ f_2(x),$ hence $f_1, f_2 \in S \longrightarrow f_1 \circ f_2 \in S.$ ii) $id$ is an isomorphism $ \longrightarrow id \in S$. iii) $ f $ is an isomorphism $ \longrightarrow \exists f^{-1}$, one can show that $ f^{-1} $ is also an isomorphism, $ \longrightarrow f^{-1} \in S$. Now, assume that $ | S | = 1$, then I want to show that $ G $ is abelian and each element has an order of 1 or 2. Im kinda lost with that $ | S | = 1 $. If $ f \in S $ then $f^{-1} \in S $ due to previous result, should not $ | S | = 1 $ imply that $ f = f^{-1} = id$? And how do I move forward from this? Any hints is muy appreciated!


I have recently installed Ubuntu 19.04 in my Lenovo ideapad along with windows 10 .   I could not find how to turn on WiFi.I could not even get anything like " No WiFi adapter found" or something like that.  I do not have any experience of using Linux.   Help me.   Edit  Output of lspci -knn | grep Net -A3; rfkill list:  Network controller [ 0280 ] : Realtek semiconductor co ., ltd RTL8821CE 802.11ac PCIe wireless network Adapter [ 10ec : c821 ] 0: ideapad_WLAN: wireless soft blocked : none , hard blocked : none


Linux Mint: How to enable cryptswap with custom password?

When you want to use hibernation and you care for security, you'd like to have the swap encrypted. But not with the random password, chosen for you at startup, but with a fixed one, supplied by you at the boot time, so the hibernated state would be available for resuming upon next boot.  There was a cool way to do this, that worked up until Mint 15:   This doesn't work anymore on Petra. Can anyone help me with working it out? The main culprit, the /usr/share/initramfs-tools/scripts/local-top script didn't change, so I guess it has something to do with the kernel. It looks like the recent kernel just ignores all the scirpt, or at least the part that asks for a password for swap.  Oh, and I was able to get the password prompt, when I accidentally booted the Mint 16 with the kernel from Mint 15.   See also a related question:       Some debug info  After opening the swap device with sudo cryptsetup luksOpen /dev/sda5 cryptswap:  sudo lsblk -o name,uuid  NAME                  UUID sda                    ├─sda1                F251-38C0 ├─sda2                c66b8e51-dd1b-4d92-8605-a3ba7df6af83 ├─sda3                77af32db-038d-4c10-b302-039634cf943a ├─sda4                7a3cde35-ab80-4618-ad76-7aa064d55f56 ├─sda5                fc068dd2-759c-4779-b521-c73cc5499e86 │ └─cryptswap (dm-1)  964eafeb-c88b-49c8-8b5e-6f8395e040b4 ├─sda6                926fa7cc-6f97-4672-85a7-a1ed8f5bd842 ├─sda7                804b9c88-907b-43d9-b23f-964c32ecc2ac └─sda8                ce2cd926-133f-4e20-86f8-45bc4844271c   └─adama-docs (dm-0) 61a32b98-3b65-4af6-81ff-da090cae039f sr0                 cat /etc/crypttab  #cryptswap1 /dev/sda5 /dev/urandom swap,cipher=aes-cbc-essiv:sha256 swap UUID=fc068dd2-759c-4779-b521-c73cc5499e86  none luks   cat /etc/fstab  UUID=926fa7cc-6f97-4672-85a7-a1ed8f5bd842   /   btrfs   defaults,subvol=@,compress,autodefrag   0   1 # /boot was on /dev/sda2 during installation UUID=c66b8e51-dd1b-4d92-8605-a3ba7df6af83   /boot   ext3    defaults    0   2 # /boot/efi was on /dev/sda1 during installation UUID=F251-38C0  /boot/efi   vfat    defaults    0   1 # /home was on /dev/sda6 during installation UUID=926fa7cc-6f97-4672-85a7-a1ed8f5bd842   /home   btrfs   defaults,subvol=@home   0   2 # /mnt/ext4 was on /dev/sda7 during installation UUID=804b9c88-907b-43d9-b23f-964c32ecc2ac   /mnt/ext4   ext4    defaults    0   0 # swap was on /dev/sda5 during installation UUID=964eafeb-c88b-49c8-8b5e-6f8395e040b4 none            swap    sw              0       0   /etc/initramfs-tools/conf.d/resume  RESUME=/dev/disk/by-uuid/964eafeb-c88b-49c8-8b5e-6f8395e040b4     update:  When I setup everything like above, the system does display the familiar password prompt. It doesn't do that every time, and if it does, it is a fraction of second before the login screen (Linux Mint uses mdm for login). I guess there is racing condition; the mounting of swap is done parallel with the system booting; I expect the system to wait booting until the swap is mounted, and do it as early as possible. Otherwise how could it resume the hibernated state?  There is a similar question for Ubuntu:  It seems, that it worked for someone if he encrypted the root as well.


Getting a NullPointerException and can't figure out why

Pretty new coder here.. Working on the Princeton algorithms one course and I'm attempting the "Stack with max" assignment. public class Stack {          private Node first = null;          private class Node {         int item;         Node next;     }          public void push(int item, Stack max) {         Node oldFirst = first;         first = new Node();         first.item = item;         first.next = oldFirst;         // if the first value is null put it to max stack         if(first == null) {             max.first.item = item;             max.first.next = oldFirst;         }         // otherwise if the item is greater than the max stack's top value, add it to the max stack         else if(item >= max.first.item) {             max.first.item = item;             max.first.next = oldFirst;         }     }          public int pop(Stack max) {         int item = first.item;         first = first.next;         // if the item removed is the max value (top of max stack) then also remove it from the max stack         if(item == max.first.item) {             max.first = max.first.next;         }         return item;     }          public static void main(String[] args) {         Stack allValues = new Stack();         Stack maxValues = new Stack();                  allValues.push(3, maxValues);     } }  Whenever I run the code, I get a nullpointerexception pointing to line 22. else if(item >= max.first.item)  I'm not sure why this is happening as I'm only trying to push an item into the max stack when the first item is not null. Any help would be greatly appreciated. Thank you :)


Suppose that $R$ is a ring. Prove that if $a\in R$, $a^2 = a$, then R is a commutative ring.  So, I know that this means that the ring multiplication is commutative. So... is this saying that for ANY $a\in R$, $a^2 = a$? Which means that every element of R is its own multiplicative inverse... But inverses, if they exist, are unique, so then the only element of R is unity. And if all you have is unity, then of course multiplication is commutative?   I'm probably way off here.  EDIT:   So, following the advice in the comments, I produced something that looks like this:  Since R is a ring, if $a,b\in R$, then $ab\in R$. Thus   $(ab)^2 = ab$  $\to (ab)(ab)=ab $  $\to (ab)(ab)a=aba $  $\to a(ba)(ba)=a(ba)$  $\to a(ba)^2=a(ba)$  So, AM I allowed to just say "by cancellation" $(ba)^2=ba$ therefore R is a commutative ring?


Can't upgrade OS Install (MATE); How to solve, please?

I have seen similar issues but am not being able to quite solve the issue... Probably easy I guess... W: Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-pt_BR) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-pt) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target CNF (main/cnf/Commands-i386) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target CNF (main/cnf/Commands-all) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-pt_BR) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target Translations (main/i18n/Translation-pt) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target CNF (main/cnf/Commands-i386) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3 W: Target CNF (main/cnf/Commands-all) is configured multiple times in /etc/apt/sources.list:52 and /etc/apt/sources.list.d/vivaldi.list:3  Appreciate a lot!


I want to have my news section repeats when i click on add button using jQuery and javascript. it repeats but repeats twice. but i want to repeat it only once, also remove button is not working i mean when i click on remove button there is no action.  need help here is my code,  HTML

               <form id="formtwo" name="formone" method="post" enctype="multipart/form-data">

News
	<input type="text" readonly="readonly" value="1" name="newsid" id="newsletter"  />

                Title of news:	                <input type="text"  name="newstitle"  />

               Description:	               <textarea rows="5" cols="30" name="description" ></textarea>

               Title of Link:	               <input type="text" name="titleoflink"  />

               URL of News:	               <input type="text" name="urlofnews"  />

               News image:	               <input type="file" name="fileToUpload" id="fileToUpload" >

               	               <input class="add" type="button" value="Add" /><input  class="remove" type="button" value="remove" />

        </form>

   JS  $(document).ready(function(){  $('.add').click(function() {        $(".test").append('

News
	<input type="text" readonly="readonly" value="1" name="newsid" id="newsletter"  />

Title of news:	<input type="text"  name="newstitle"  />

Description:	<textarea rows="5" cols="30" name="description" ></textarea>

Title of Link:	<input type="text" name="titleoflink"  />

URL of News:	<input type="text" name="urlofnews"  />

News image:	<input type="file" name="fileToUpload" id="fileToUpload" >

	<input class="add" type="button" value="Add" /><input class="remove" type="button" value="remove" />

');   });   });     $('.remove').click(function() {     if($(".test tr").length != 2)      {         $(".test tr:last-child").remove();      }   else      {         alert("You cannot delete first row");      } });


If $n$ is a positive integer such that the sum of all positive integers $a$...

I am stuck with the following problem that says:  If $n$ is a positive integer such that the sum of all positive integers $a$ satisfying $1 \le a \le n$ and GCD $(a,n)=1$ is equal to $240n,$ then the number of summands ,namely,$\phi(n),$ is  $120$ $124$ $240$ $480$   MY TRY: Just for understanding, if  I take $n=5,$then $a_i$'s such that gcd $(a_i,5)=1$ and $\sum a_i=240\times 5$. But, $a_i$'s can only be $1,2,3,4$ ,since $n=5$. Now, I do not know which way to go. Can someone explain? Thanks in advance for your time.


How to add musical symbols like flats and sharps in text

I need a to use musical symbols, flats, sharps and such in my thesis. This is what I would like it to look like:    I use ShareLaTeX, the online LaTeX thing.


Should you declare methods using overloads or optional parameters in C# 4.0?

I was watching , and it got me thinking about when optional parameters are available in C# what is going to be the recommended way to declare methods that do not need all parameters specified?  For example something like the FileStream class has about fifteen different constructors which can be divided into logical 'families' e.g. the ones below from a string, the ones from an IntPtr and the ones from a SafeFileHandle.  FileStream(string,FileMode); FileStream(string,FileMode,FileAccess); FileStream(string,FileMode,FileAccess,FileShare); FileStream(string,FileMode,FileAccess,FileShare,int); FileStream(string,FileMode,FileAccess,FileShare,int,bool);   It seems to me that this type of pattern could be simplified by having three constructors instead, and using optional parameters for the ones that can be defaulted, which would make the different families of constructors more distinct [note: I know this change will not be made in the BCL, I'm talking hypothetically for this type of situation].  What do you think? From C# 4.0 will it make more sense to make closely related groups of constructors and methods a single method with optional parameters, or is there a good reason to stick with the traditional many-overload mechanism?


Converting Raw HTTP Request into HTTPWebRequest Object

In .NET is it possible to convert a raw HTTP request to HTTPWebRequest object?  I'm sure .NET internally doing it. Any idea which part of the .NET is actually handling this? Can I call it or is there any external library which allows raw HTTP connections?


apt-get update command results in 404 Not Found error

Please help with this error.   sudo apt-get update  W: Failed to fetch http://ppa.launchpad.net/upubuntu-com/office/ubuntu/dists/saucy/main/binary-i386/Packages  404  Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.


The anti-particle corresponding to a proton or an electron is a particle with an equal mass, but an opposite charge. So what is the anti-particle corresponding to a neutron (which does not possess a charge)? And if it is just another neutron, will its collision with the original neutron be as destructive as the collision of a proton with an anti-proton or an electron with an anti-electron?


I've read a lot of conflicting advice on whether it's advisable to store eggs in the refrigerator. The case against seems twofold: (1) that eggshells are porous, and eggs can take on unwelcome flavours, or even spoil faster in the fridge, and (2) that cooking with cold eggs can be problematic. But lots of people refrigerate eggs through perceived necessity.  Do eggs last longer in the fridge, and is the shelf life gain worth it? Or should I just stick them in the cupboard?


Continuous and Differentiable function with discontinuous derivatives

Is it possible for a function to be continuous and differentiable in an interval, but its derivative over that interval is not continuous?


File /etc/resolv.conf deleted on every reboot, why or what?

I am having an issue where DHCP (I though as I read in other similar topics) is clearing the /etc/resolv.conf file on each boot. I am not sure about how to deal with this since the post I have found (,  and some others) are for Debian based distros or other but not Fedora.  This is the output of ifcfg-enp0s31f6 so for sure is DHCP:  cat /etc/sysconfig/network-scripts/ifcfg-enp0s31f6  HWADDR=C8:5B:76:1A:8E:55 TYPE=Ethernet DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=no IPV6_AUTOCONF=no IPV6_DEFROUTE=no IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=enp0s31f6 UUID=0af812a3-ac8e-32a0-887d-10884872d6c7 ONBOOT=yes IPV6_PEERDNS=no IPV6_PEERROUTES=no BOOTPROTO=dhcp PEERDNS=yes PEERROUTES=yes   In the other side I don't know if Network Manager is doing something else around this.  Update: Content of NetworkManager.conf (I have removed the comments since are useless)  $ cat /etc/NetworkManager/NetworkManager.conf  [main] #plugins=ifcfg-rh,ibft dns=none  [logging] #domains=ALL   Can I get some help with this? It's annonying be setting up the file once and once on every reboot.  UPDATE 2  After a month I'm still having the same issue where file gets deleted by "something".   Here is the steps I did follow in order to make a fresh test:   Reboot the PC After PC gets restarted open a terminal and try to ping Google servers of course without success:  $ ping google.com ping: google.com: Name or service not known  Check the network configuration were all seems to be fine:  $ cat /etc/sysconfig/network-scripts/ifcfg-enp0s31f6  NAME=enp0s31f6 ONBOOT=yes HWADDR=C8:5B:76:1A:8E:55 MACADDR=C8:5B:76:1A:8E:55 UUID=0af812a3-ac8e-32a0-887d-10884872d6c7 BOOTPROTO=static PEERDNS=no DNS1=8.8.8.8 DNS2=8.8.4.4 DNS3=192.168.1.10 NM_CONTROLLED=yes IPADDR=192.168.1.66 NETMASK=255.255.255.0 BROADCAST=192.168.1.255 GATEWAY=192.168.1.1 TYPE=Ethernet DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=no  Restart the network service:  $ sudo service network restart [sudo] password for <current_user>:  Restarting network (via systemctl):                        [  OK  ]  Try to ping Google servers again, with no success:  $ ping google.com ping: google.com: Name or service not known  Check for file /etc/resolv.conf:  $ cat /etc/resolv.conf  cat: /etc/resolv.conf: No such file or directory  File doesn't exists anymore - and this is the problem something is deleting it on every reboot Create the file and add the content of DNS:  $ sudo nano /etc/resolv.conf   Ping Google servers this time with success:  $ ping google.com PING google.com (216.58.192.110) 56(84) bytes of data. 64 bytes from mia07s35-in-f110.1e100.net (216.58.192.110): icmp_seq=1 ttl=57 time=3.87 ms    Any ideas in what could be happening here?


How do I get into contact with the IRS to ask some tax questions?

Way back in March I filed my taxes, and applied for a payment plan. My request actually never went through, and I ended up having to re-apply on April 20th. The representative I talked to said that my plan would start in May and would end in August.  Since then I have received 3 letters from the IRS; the first one came around the first week of May, and stated that my taxes weren't done processing, so my payment plan wasn't active yet. The next two letters were notifications telling me to cancel my payment plan if I didn't sign up for one. Then nothing.  I would like to get in contact with the IRS, and talk to an actual person about the status of my plan and ask the following questions: Should I be making payments if it isn't done processing? Will my payment plan begin once my taxes are done processing? Will I be held responsible for money owed in May if I did not receive any sort of notification informing me of the obligation?  The question I am asking here is just how to reasonably get into contact with the IRS. How can I talk to someone who can find all these answers for me? Their web portal for payment agreements has never worked for me, and all the phone numbers are just touch tone mazes filled with dead ends.  I really would like to be able to budget for my future, but I have no clue what the IRS is expecting of me at this time.


After I editted my .bashrc I got ghosts in my prompt

I added the following to my ~/.bashrc:  export PS1="\e[0;35m[\u@\h \W]\$ \e[m " echo -e "\e[0;35mYOU ARE ON THE LIVE SERVER !!\e[0m"   sadly, now, every time I paste something long into bash it goes squiffy and ghost tab characters appears all over the screen, and lines eat each other, does anyone know why?


When "of course" is at the end of a sentence, should a comma precede it?


Unchained Monk, Unarmed attacks, Natural attacks, and Flurry of Blows: Counting the Attacks

So, my question, and I haven't found a succinct, well laid out answer anywhere (if you have, please share), but how many attacks does an unchained monk with natural attacks get, and is it worth flurrying?  The scenario is a level 3 Tiefling Unchained Monk with Maw or Claw Alternate Racial Trait, choosing the 2 claw attacks, and the feats Feral Combat Training and Weapon Focus (Claws).  By my understanding, a full attack would allow 1 unarmed attack at +3 (assuming 10 str) and 2 claw attacks at -1 (+3bab, +1 weapon focus, -5 secondary), or:  UA+3, Claw -1, Claw -1  Also by my understanding, a Flurry of Blows would be 1 attack (unarmed or claw), and then the Flurry of Blows attack which also could be an unarmed or claw attack, but at full bab, so it would look like this:  UA+3, FOB UA+3 or Claw+4, FOB UA+3 or even Claw+4, FOB Claw+4  So, you end up with 1 less attack, but at higher chance to hit.  Is this accurate?  Or am I missing something?  And to make sure I'm not missing anything at higher levels, what would level 6, 11, and 16 look like?  Ultimately, again, is Flurrying worth it if you have natural attacks?


Why didn't the Enterprise-E crew just use holodeck machine guns against the Borg?

Picard is pursued by the Borg while they take over the Enterprise-E. He starts a chapter of some crime-drama holo-novel on the holodeck. The crime boss and his henchmen carry tommy guns, which Picard steals to shoot at the Borg drones. He also turns off the safety protocols on the holodeck so that the bullets are real.                                  We see that bullets can kill Borg drones.  We know from ST:TNG episodes that physical objects can be removed from the holodeck. (Water in the pilot episode, Encounter at Far Point, and a piece of paper in the episode, Elementary, Dear Data.)  This means Picard should be able to take the tommy guns out of the holodeck to kill the Borg.  Not just that, but he should be able to tell the holodeck to create "guns, lots of guns".                                  Could Picard have brought the tommy guns out of the holodeck?  Edit to add from comment: Even if Picard can't bring a working tommy gun out of the holodeck, he could still ask the replicators to make tommy guns. That's a good point by Rebel-Scum and still fits within the overall question. Why not use projectile weapons against the Borg?  Could the Borg have adapted quickly to projectile weapons to make that tactic useless?


What does typedef enum syntax like '1 << 0' mean?

I'm somewhat familiar with the typedef enum syntax of C and C++.  I'm now programming in Objective-C and came across the syntax in the following example.  I'm not sure if the syntax is Objective-C specific or not.  But, my question is in the following code snippet, what does syntax like 1 << 0 mean?  typedef enum {    CMAttitudeReferenceFrameXArbitraryZVertical = 1 << 0,    CMAttitudeReferenceFrameXArbitraryCorrectedZVertical = 1 << 1,    CMAttitudeReferenceFrameXMagneticNorthZVertical = 1 << 2,    CMAttitudeReferenceFrameXTrueNorthZVertical = 1 << 3 } CMAttitudeReferenceFrame;