On my server spamming files are uploaded , which start with   <?php ${"\x47\x4cO\x42A\x4c\x53"}["cgw\x71\x77\x77\x64\x79q"]   I'm trying to find all files on server which is having above string and delete the file.  For that I'm using following command.    find . | xargs grep -l -r '<?php ${/"\x47\x4cO\x42A\x4c\x53/"}' /home/ | awk '{print "rm "$1}' > doit.sh   But seems it is not working. Anyone have suggestion for command so that i can delete all this malicious file.


How do I overcome "permission denied" when using sudo?

I’m using Ubuntu 14.04.  I’m having trouble clearing out a file.  I’m getting permission denied even though I’m using sudo.  Here’s what’s happening …  myuser@mymachine:~$ sudo chmod 755 /var/log/unicorn/unicorn.log myuser@mymachine:~$ sudo echo '' > /var/log/unicorn/unicorn.log -bash: /var/log/unicorn/unicorn.log: Permission denied myuser@mymachine:~$ ls -al /var/log/unicorn/unicorn.log -rwxr-xr-x 1 rails root 304746186 Dec 31 15:08 /var/log/unicorn/unicorn.log   What evil demonic possessions have taken over and how can I conquer this crazy file?


Can my father sponsor me for Schengen visa?

I belong to a third country going on a Schengen visa to Spain as a tourist. But I am currently a student who wants to travel and experience the startup culture. Can my father residing in my home country sponsor me for the whole trip? What formalities he has to make for it ?


Constant factor in centering inequality of sub-gaussian distributions?

Subgaussian norm of a random variable $X$ is defined as: $$ \|X\|_{\psi_2} = \inf\left\{t > 0: \mathbb{E}\left[e^{\frac{X^2}{t^2}}\right] \leq 2\right\}. $$ For $L_2$ norm of a random variable we can write $\|X - \mathbb{E}[X]\|_2 \leq \|X\|_2$ which is called centering inequality. It is easy to prove that a similar inequality holds for subgaussian random variables as well. Namely, $$ \|X - \mathbb{E}[X]\|_{\psi_2} \leq C\|X\|_{\psi_2} $$ for some $C \geq 1$ which does not depend on $X$. I would like to see if this inequality holds for $C = 1$?


I was planning to design a database (relational model). Someone with good experience in this matter suggested to me that before choosing a  database system I would have to consider the sizing of the database and other factors. I have been reading quite a lot. I bumped into a lot of information of database (relational model) however I can not find information on previous stages of database design to be considered. How can I measure the sizing of the database?


Why my overload inherit function is not hiding a base function?

I have this code:  enum type{FOO, BAR}  class base{     funct(type t); } class other : base{     funct(type t); }  int main(){     base x;     x = other();     x-funct(FOO); //This call base::funct() }   Always call to base function, i dont get it.


Holomorphic function between $\{z\in \mathbb{C}: 1\leq |z|\leq 4\}$ and $\{z\in \mathbb{C}: 1\leq |z|\leq 2\}$

Does there exist a holomorphic function $h$ that sends the set $\{z\in \mathbb{C}: 1\leq |z|\leq 4\}$ to the set $\{z\in \mathbb{C}: 1\leq |z|\leq 2\}$?   I tried proving it but I could not.  Thanks for your help


Asp.Net MVC PartialView MasterDetail Page with ajax scripts stop working

Im trying to make an asp.net mvc View with 2 PartialViews who get their informations by an ajax call with javascript.

                     <input id="CategoryName" class="form-control" />

                 <input id="AddCatButton" type="button" class="btn btn-default custombtn" value="asd" />

                 @Html.PartialFor("_Categories", Model.Categories, "Categories")

                 <input id="CategoryItemName" class="form-control" />

                 <input id="AddItemButton" type="button" class="btn btn-default custombtn" value="asd" />

             @*Contentn of the Detailpage*@

   everythings is working fine i can name and add a new Category the Partialview will "refresh" and then the scripts stop working.  ive included them in the _Layout.cshtml   The script calls the Controller and give back an PartialView("_Categories",model) with every category in the database and also a second method gives back every item of a category but the script stopped working until i reload the whole page.  ive tried it to include the scripts on each partialview but then when i created a new category it creates 2,4,8,16,and so on Do I habe to include the script somewhere elöse or what is the solution.  The Javascript is one script with 3 Methods in it    $("#CatList li").on('click', function () { //    Shows all items in a category and refresh the itemlist partialview  }); $("#AddItemButton li").on('click', function () { //    Adding an item to the selected Category //    and refreshes the itemlist partialview }); $("#AddCatButton li").on('click', function () { //    add a Category and refresh the category partialview  });


I have an XML File for an API. The API responses everytime "Errormesage: Expected argument of type "string", "array" given".   $SimpleXML_loaded_File = simplexml_load_file("http://graphics.edc-internet.nl/b2b_feed.php?key=tc62te28wt3e2t73ctr9c1cw42601337&sort=xml&type=xml&lang=de");  foreach ($SimpleXML_loaded_File->product as $product) {    /*$client->post('articles', array(       'name' => $product->titel,       'taxId' => 1,       'supplier' => $product->merk,       'mainDetail' => array(           'number' => $product->artikelnummer       )   ));*/  echo "<pre>"; var_dump($product->artikelnummer); echo "</pre>";  }   If i var_dump the Output i dont get a string i`m getting the object  object(SimpleXMLElement)#6 (1) {   [0]=>   string(7) "0633178" }   How do i get only the string ?


Why are FTP connections read-only when I use "Connect to Server..."?

I'm just trying to connect to the server hosting my website through Finder, but it's always read only, even though I'm logging in with my username and password.  Obviously, I can connect with an FTP client (Fetch), and through the terminal, etc. – but what's the trick to FTP-uploading with Finder?


Binomial regression does not give coefficients for all IVs

I have a dataset with the dependent variable presence / absence (0 and 1) for a certain species. I have three categorised IV's (2 IV's with 3 categories and 1 with 2 categories). To test the response of the presence / absence to the 3 IV's, I have to perform a binomial regression, right?  I can run a model in R which looks like this:  glm(species.presenceabsence~TREATMENT+WEEK+TYPE, data=speciesdata, family=binomial))   The outcome looks like this:  Coefficients:                Estimate Std. Error z value Pr(>|z|) (Intercept)    -19.4779  2955.2811  -0.007    0.995 TREATMENTHigh  -19.1984  2955.2812  -0.006    0.995 TREATMENTLow    -0.9217     0.8101  -1.138    0.255 WEEK10          18.2767  2955.2812   0.006    0.995 WEEK15          19.1984  2955.2812   0.006    0.995 TYPEF           -0.3083     0.7881  -0.391    0.696   What I don't understand is why R doesn't give the coefficients of all the IV's. How do I interpret these data? I'm a bit surprised that none of the coefficients has a significant effect.


Clicking community promotion ad renders an instance of SO within the frame of that ad

Today I came across an ad on this question on SO:  (I don't expect it to stay very long).   There was a community promotion ad on the right hand side of the site, I think for one of our English sites. It had a sentence that I only partially remember:     Idiom ... poor or even poorer   I found it interesting, so I clicked that ad. Which caused a new instance of SO to open within the ad space. Unfortunately I failed to take a screenshot. I've been refreshing the page like crazy, but can't get the ad to appear again.  Edit: I managed to get a new community add, for the photography site, and captured a screenshot:   Edit2: This bug still persists, I saw it today with an OOP add from CodeReview, and an area 51 add.


Finding a sufficient statistic for a rectangular distribution

Iam trying to use this theorem for the problem below:     a statistic is sufficient for $\mathcal{P} = \{P_{\theta}: \theta \in \Theta \}$ iff there exist nonnegative functions $g(\cdot; \theta)$ and $h$ such that the probability  functions $p(\cdot ; \theta)$ satisfy:   \begin{equation}p(\boldsymbol{x};\theta) = g(T(\boldsymbol{x});\theta )h(\boldsymbol{x}) \end{equation}  suppose $(x_1,...,x_n)$ represent independent  realisations of a random variable $X$, uniformly distributed over the interval $(\theta-1,\theta+1)$. The 'book' claims that a sufficient statistic for $\theta$ is $T(x) = (x_{(1)},x_{(n)}-x_{(1)})$   this is what i tried:  $f(\boldsymbol{x};\theta) = \prod\limits_{i=1}^{n} \dfrac{1}{(\theta+1)-(\theta-1)}\mathbb{1}_{(\theta-1,\infty)}(x_{(1)})\mathbb{1}_{(-\infty,\theta +1)}(x_{(n)}) =\dfrac{1}{2^n} \cdot\prod\limits_{i=1}^{n}\mathbb{1}_{(\theta-1,\infty)}(x_{(1)})\mathbb{1}_{(-\infty,\theta +1)}(x_{(n)}) $  But i get that the sufficient statistic has to be $T(x) = (x_{(1)},x_{(n)})$, maybe another sufficent statistic is $T^*(x) = (x_{(1)},x_{(n)}-x_{(1)})$ but can someone tell me how?


I am trying to connect to a Linode (running Ubuntu 12.04 LTS) from my local machine (also running Ubuntu 12.04 LTS)  I have created a private and public key on my local machine and copied my public key to my Linode's authorized_keys file.  However, whenever I try to ssh to my Linode I get the error message Permission denied (publickey).    It's not a problem with how ssh is set up on my Linode because I can ssh to it from my Windows machine using key authentication.    In my .ssh directory on my local Ubuntu machine, I have my id_rsa and id_rsa.pub files.  Do I need to create an authorized_keys file on my local machine?    EDIT:  This is what I get when I run ssh -vvv -i id_rsa [youruser]@[yourLinode]:  debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey).


Bibtex, citations and bibliography not showing

I downloaded this thesis template:    PROBLEM: Citations not working and bibliography not showing:     This is BibTeX, Version 0.99d (TeX Live 2016) The top-level auxiliary   file: main.aux I found no \citation commands---while reading file   main.aux I found no \bibdata command---while reading file main.aux I   found no \bibstyle command---while reading file main.aux (There were 3   error messages)   I am using TexMaker.   I tried several solutions online but nothing worked.


Installing a new 3 way dimmer switch - on the back of it there is the green grounding wire, the white neutral wire, 2 'traveler' outlets and 1 line/load outlet.  However, the wiring when I removed the switch has 1 wire (it was white but wrapped in black electrical tape), and then another black and red wire (which I assume are the 2 traveler wires) and the ground wire which I connected to the green wire from the dimmer switch....so I only have 3 other wires, but 4 more connections on the dimmer switch...


How should I order the members of a C++ class?

Is it better to have all the private members, then all the protected ones, then all the public ones?  Or the reverse?  Or should there be multiple private, protected and public labels so that the operations can be kept separate from the constructors and so on?  What issues should I take into account when making this decision?


Can I use a Thunderbolt display for a macbook pro with a mini display port?

I have an older macbook pro with a mini display port. Can I use a Thunderbolt display as an external monitor?


Do the Nine Kings of Men still wear the rings after turning into Nazgûl?

Sauron gave several rings of power to many species that inhabited Middle Earth. The men were the most gullible and had been transformed into wraiths that are loyal to Sauron. After this transformation, did the wraiths continue to wear their rings or did they get rid of them? Or does Sauron need to have the rings on the Nazgûl to maintain his control over them?


PATH variable not working properly with hg

I am having a CentOS remote machine where I have hg installed. It was working fine for long time and today when I am trying to use hg  commands, I got the following errors,  [dinesh@lab test]$ hg st -bash: hg: command not found [dinesh@lab test]$   Then I realized that it might be missed from PATH. (But, how?, not sure.). I checked the which hg command and it failed to give me the path.  hg is located at /usr/local/bin/hg and using the whole path for hg, made it work. I tried adding the hg path to PATH variable like,   PATH=$PATH:/usr/local/bin/hg   which also didn't work. Then I have created an alias for hg command as,  alias hg="/usr/local/bin/hg"   which at least made it work.   But, eventually, I end up with the same issue for kdiff3 (which is also working fine till yesterday). Tried the above and only alias made it work. (again)  Now, I am in need of using hg kdiff3 command and for which I am keep on getting   /bin/sh: kdiff3: command not found   But, I have the kdiff3 extension enabled in the hgrc file for the repository. (which is again working till yesterday)  :(  [dinesh@lab test]$ cat .hg/hgrc [paths] default = ssh://remoteuser@xxx.xx.xx.xxx//repo/code  [ui] username= dinesh <dinesh.sivaji@domain.com>  [extensions] mq = fetch = purge = hgext.extdiff = hgext.acl =  [extdiff] cmd.kdiff3 =  [dinesh@lab test]$      Note : After making changes in the .profile file for PATH or alias, I am sourcing them each time, for changes to take effect.   Can anyone suggest what can I do to overcome this issue ?


Using Fermat's little theorem to find remainders.

I don't understand how to use Fermat's little theorem to find remainders e.g if we are asked to find remainder of 50^50 on division by 13, what is a and what is p in the formula? What is going on?? Are we using congruence classes when using Fermat's little theorem? Can someone please give me a step by step explanation from the beginning, I'm  just not understanding this stuff.


Splitting a sandwich and not feeling deceived

This is a problem that has haunted me for more than a decade. Not all the time - but from time to time, and always on windy or rainy days, it suddenly reappears in my mind, stares at me for half an hour to an hour, and then just grins at me, and whispers whole day: "You will never solve me..."  Please save me from this torturer.  Here it is:  Let's say there are two people and a sandwich. They want to share the sandwich, but they don't trust each other. However, they found the way how both of them will have a lunch without feeling deceived: One of them will cut the sandwich in two halves, and another will choose which half will be his. Fair, right?    The problem is:  Is there such mechanism for three people and a sandwich?    EDIT: This was roller-coaster for me. Now, it turns out that there are at least two books devoted exclusively on this problem and its variations:          Yesterday, I was in a coffee shop in a small company. We ordered coffee and some chocolate cakes. As I was cutting my cake for my first bite, I felt sweat on my forehead. I thought, 'What if some of my buddies just interrupt me and say: Stop! You are not cutting the cake in a fair manner!' My hands started shaking in fear of that. But, no, nothing happened, fortunately.


Proof involving Fibonacci number and binomial coefficient

Question: Let $F_m$ be the mth Fibonacci number given by $F_1=F_2=1$ and $F_{m+2} = F_m + F_{m+1}$ for all $m\ge1$.   Show that  $\sum_m(C_{n,k})=F_{m+1}$ ;  here the sum is over all pairs of integers $n\ge k\ge0$ with $n+k=m$.  My Approach: $F_3=2,F_4=3,F_5=5$;  Now for $m=4$: $F_5=5$ and $(n,k)$ for $m=4$ are $(4,0),(3,1),(2,2)$, so $\sum_{n+k=4} C_{n,k}=C_{4,0} + C_{3,1} + C_{2,2} = 1+3+1 = 5 $.  Next how can i proceed??


I noticed that the shown communities on the profile of every user are ordered by the reputation the user has in the different community.        But if an user has the same reputation in two communities they seem to be ordered randomly. This is also metioned in .         I would suggest to change this so it is sorted by the overall activity in the specific communities, for example based on posts and/or badges or even based on personal preference.


Bootcamp: The startup disk does not have enough space to be partitioned

When clicking continue on the first Boot Camp screen,  I am presented with a dialog that displays:     The startup disk does not have enough space to be partitioned.   You must have at least 39 GB of free space available.     This is despite "About this Mac" reporting 271GB of free space:    And "Disk Utility" reporting 268GB of free space:    Searching online I found  which suggested it was the result of Time Machine which i recently enabled and suggests to run sudo tmutil thinlocalsnapshots / 999999999999 which I did, it ran sucessfully, and I restarted, yet to no avail.  What is the solution to this instance of Apple's poor engineering?  Running macOS High Sierra 10.13.4 (17E202)


I used a template from overleaf, I can not figure out which setting made this problem happen, so .  And the problem is in the file:     Chapters/Chapter1.tex   on line 30:  \caption{Related work \label{table:related_work}} \\     I tried:  \setcounter{table}{0}   But it doesn't seem to make any difference.


I've generated the simplest code I could think of to illustrate my problem.  Suppose I want the "foo" command to work with files that end with ".cc".   complete -G '*.cc' foo   Now let's suppose my current directory contains "foo.cc", "bar.cc", and "blah.cc". If I type "foo" and tab, I get:  $ foo <tab><tab> bar.cc   blah.cc  foo.cc    $ foo    which I expected. But if I type the first letter 'b' and try again:  $ foo b<tab><tab> bar.cc   blah.cc  foo.cc $ foo b   It didn't filter the results to those that start with 'b' as it would have for -W.  I've searched everything I could find, and haven't found an example of complete -G that does what I want. I'm sure this is a common-enough thing to do; what's the best practices here?


When asking a question, could the page suggest relevant tags?

Sometimes when I'm new to a SE site I end up having to come up with some tags for my question that don't really fit into what people normally use on the site. Is there any way we could have the "ask question" page make some suggestions for what tags you might want to use for a particular question based on the question text?


Whenever I attempt to login, I end up getting redirected back to the homepage and not be logged in. I am getting a 404 error:  Failed to load resource: the server responded with a status of 404 (Not Found)


How to change number of vertices for cylinder after created it?

I've created a cylinder object which is fine at first. But as modeling goes by I've decided to change some properties,like number of vertices, of the cylinder just to see it in real-time. But cannot find the solution. Search the internet only come up as using "Adjust Last operation". I know I can just add new one. But for the sake of knowledge and future work flow. Thanks in advance.


Singular or plural verb following "any" with a plural noun

Is it correct to say "If any of the parties are required,...."?  Is it correct to say, "If any of the parties is required,...."?


Initialization of all elements of an array to one default value in C++?

has a nice list over initialization of arrays. I have a  int array[100] = {-1};   expecting it to be full with -1's but its not, only first value is and the rest are 0's mixed with random values.  The code  int array[100] = {0};   works just fine and sets each element to 0.  What am I missing here.. Can't one initialize it if the value isn't zero ?  And 2: Is the default initialization (as above) faster than the usual loop through the whole array and assign a value or does it do the same thing?


Create reference to variable based on another variable name in a bash script?

Assume I've got these variables in a bash script:  path_family="/home/family" path_family_log="/var/log/family.log" path_friends="/home/friends" path_friends_log="/var/log/friends.log" path_pets="/home/pets" path_pets_log="/var/log/pets.log"   I want to create a for loop where I could do something like the following:  for TYPE in family friends pets do   for FILE in $path_<TYPE>   do     cat $FILE >> $path_<TYPE>_log   done done   Obviously this isn't correct code, just most direct way to express what I want. I'm pulling my hair out trying to figure out how to do the substring substitution on the variable name and have it work as intended.


vmplayer never keep virtual machines on library?

I have installed "Vmplayer(version 6.0.2 build-1744117)" on my Ubuntu 14.04 LTS.   I have created 3 virtual machines on my home directory. When i open vmplayer, library always empty and every time i have to browse and select them to open. I tried different folder permissions and it didn't help. current folder permission is 755 and owner is current user(me).   How do i keep my vms on library, any idea? thanks.


The Hadamard Operator on one qubit is:  \begin{align*} H = \tfrac{1}{\sqrt{2}}\left[\,\left(\color{darkgreen}{|0\rangle + |1\rangle}\right)\color{darkblue}{\langle 0|}+\left(\color{darkgreen}{|0\rangle - |1\rangle}\right)\color{darkblue}{\langle 1|}\,\right] \end{align*}  Show that: \begin{align*} H^{\otimes n} = \frac{1}{\sqrt{2^n}}\sum_{x,y}(-1)^{x \cdot y}\,\left|x\rangle \langle y\right| \end{align*}  I can evaluate things like $H \otimes H$ in practice, but I don't know how to get a general formula for $H^{\otimes n}$. Are there any tricks I could use?


list all suggested packages for currently installed packages

Every time I install a package:  sudo apt-get install <pkg>   apt-get displays a list of suggested packages. I have simply ignored these so far, but some of these suggestions are actually good (and some are not). I would like to recover all these lists into one big list (so that I can review it and decide if there is some package I want to install), but I could not see them in /var/log/apt/history.log.   That is, I'm looking for something like  list = [] for package in installed_packages:     list.append(package.name) print list


Process substitution and cat: can't read stdin

The process substitution <(cat) doesn't work. Why?  head <(cat)  cat: -: Input/output error   I can use an extra file descriptor, but I don't understand why the above doesn't work.  # Using file descriptor 3 to reroute the input (head <(cat <&3)) 3<&0


The following is an image of the AND logic gate from  and my representation of that in EveryCircuit, where I've used the "Logic input" as the A/B inputs on the left (equivalent to a 5V battery).     Is this the correct representation of the AND circuit? Additionally, what is the usual voltage or current requirement for an A/B input to be considered in the 'on' position?


Quorum for 3 nodes AlwaysOn Availability Group

If I am going to set an Alwayson Availability group with 3 nodes, with read-only routing. Do I need to configure a Quorum ?


Closed form of $\int_0^\infty \sin(x)\sin\left(\frac{1}{x}\right)dx$?

I have stumbled onto an interesting integral$$\int_0^\infty \sin(x)\sin\left(\frac{1}{x}\right)dx$$ which I noticed graphically that it appears to be $1$, but I have no idea on how to evaluate it. Maybe it could be done with the use of Bessel Functions? Any help is appreciated.


How much did Lucius Malfoy know about the workings of the diary?

From CoS (or was it from HBP?) we get a very vague hint at how much Lucius knew about the diary; Dumbledore tells Harry that Voldemort probably told Lucius that the diary would help open the Chamber of Secrets, and there was some plan that Voldemort wanted to put into action, which never happened because his power got destroyed when he attacked Harry (sorry I don't remember the exact scene).    Non-the-less I doubt Voldemort told him any details on how the diary worked. He had to keep his horcruxes a top secret, and somehow I don't see him telling Lucius that the diary had his actual memories locked inside of it, and that it had the capability to possess other people. However, from book 2 we know that Lucius knew enough to plant the diary on a student going to Hogwarts, that it would definitely open the Chamber of Secrets, and somehow the student who had the diary planted on would be blamed for it (which was the reason he planted it on Arthur Weasley's daughter). We also know that a lot of the things in book 2 happened due to pure luck. After Ginny threw the diary down Myrtle's toilet, it just happened to have been picked up by Harry. It might have been picked up by anybody, might have been flushed down a different toilet entirely (the reason it was even found by Harry was because Myrtle threw it back out), or it might not have been taken to Hogwarts in the first place (if Ginny's parents had checked her books after returning home from Diagon Alley before giving them to her, they might have realized the diary was not something they bought and might have just kept it at the house, possibly even recognized that it had some dark magic on it).    So I am curious to know, how much about the diary did Lucius know exactly? What was he hoping would happen? Did he think it would just cause chaos, or even cause Voldemort to come back somehow (this I doubt, seeing how scared he was when Voldemort did come back in book 4, and he doesn't seem like the person to be that loyal, to actually want Voldemort to come back)? Is any information available on this topic?


For which values is polynomial divisible by a prime number?

Let $f=aX^2+bX+c \in \mathbb{Z}[X]$ be a quadratic polynomial and $p$ a prime number. I need to find all solutions $x \in \mathbb{Z}$, s.t. $p$ divides $f(x)\in \mathbb{Z}$. I'm sure there is an algorithm for it, but unfortunately I don't know it.


A basic question: Where do I find the command line?  There is a lot of information about commands and using the command line, but I'm an absolutely new Ubuntu user: I can't find find the command line.


Web server benchmark - explanation of results?

I made a small benchmark, in which I compare Apache HTTP server deployed to the Virtualbox, and Apache HTTP in Docker (official Alpine and Debian based images) deployed to the Virtualbox. The results of average requests per second are in the following image .  The question is what cause the performance peaks?   For benchmark was used abc (GWAN) wrapper with weighttp. Settings of VM were updated according to   Benchmark run with [0-500:3000+10x3] => make 3000 request with concurrency from 0 to 500 (with step 10). Every test repeat for 3 times. Configurations of HTTP servers were untouched (default by install). Virtualbox instances were made via Vagrant (Debian Stretch).  I also expect, the default configuration caused that the native Apache HTTP server was slower (with higher concurrency) than the Docker instance. I made the same test for Nginx and results shown same performance stability of docker instance.  BTW, the conclusion of the comparison: performance differences between docker images based on Alpine and Debian are insignificant.


What is the value of $\displaystyle\sum_{k=1}^{\infty}\frac1{(3k+1)(3k+2)}$?


How do I search for available packages from the command-line?

I have successfully installed some packages using the command line 'sudo apt-get install packagename' when I have known in advance that those packages are available.  But how can I search for or get a list of what is available in the repositories?


I can't seem to figure out:  How can I make my website look/check csgo.steamanalyst.com or steamcommunity.com/market market for Counter-Strike Global Offensive skin prices?  I have made so people can log onto my webpage and I got all information of the logged in user, except the password ofc. I'm making a CSGO betting website. I have everything made, I just need some kind of script, that checks what the skins are worth on steamcommunity or steamanalyst.   Thanks in advance.


How do I create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office?

How can I create an Excel spreadsheet with C# without requiring Excel to be installed on the machine that's running the code?


\sqrt: The vinculum and the rest of the radical are misaligned

When the height of the radicand exceeds a certain threshold, LaTeX replaces the check-sign-like part of the root sign with a more vertical one. This behavior has a flaw: The vertical replacement part does not align properly with the vinculum (the horizontal bar). For example,  \documentclass{article} \begin{document} \[ \sqrt{\sqrt{\sqrt{\sqrt{\sqrt{\sqrt{\sqrt{}}}}}}} \] \end{document}   produces  .  I've found a few related questions here on Stack Exchange. The question  is nominally about LuaLaTeX, but the first comment, by user egreg, seems to imply that the question is related to mine. The comment blames the PDF rendering, and there may be some truth to that — the misalignment seems less noticeable to me on a high-density screen (eg. the retina MacBook Pro). However, it's not a problem with any single PDF viewer: I've seen the misalignment in Latexian, Preview, and Skim on OS X, in Adobe Reader on Windows, and on a printed copy.  The solitary answer to that question, by the way, doesn't seem to relate my problem.  The misalignment is also evident in the question . Its solution produces a slanted radical, but leaves a noticeable gap between the two components of the radical.  Does anyone else see the misalignment? Any idea what the underlying cause is? And are there any workarounds?


How do I migrate from SO to apple.stackexchange.com (not on the list)

is on how to use an OSX program and would seem ideal for apple.se.  However, the only migration options are meta, superuser, tex, dba and sharepoint, none of which are at all suitable.


Why are my render times 30+ minutes, but other people's are ~3 minutes?

I am currently using Sheep It! to render my blend (built on v2.68c) on multiple computers, and I noticed something rather strange. According to the log on-site, the frames rendered from other people's blends were completing in 3 to 4 minutes. This was on an 4 core i5. My main rig (with an 8 core i7) was completing frames in no less than half an hour. How is this possible?  To clarify, these people's frames are very complex, often with very detailed textures. I have 2 objects in my blend. Below are the options I changed for my blend:   Aspect Ratio: 1000px x 1000px Output: PNG Clamp Indirect: 0.98 Render Sampling: 128 Min Light Bounces: 0 Max Light Bounces: 4 Cycles Render   Is there something in there that I should change to make it go faster? I can't really comprehend how it's going to quickly.  EDIT: To answer what @Duarte asked...   System Specs: i7-920, 3GB DDR3, GT 630, Windows 10 I have two circles, extended to form a sort of coin with a star on it. It is not complex at all. I have Firefox and Steam running in the background, but not actively. I've been away from the computer for 8 hours and noticed this behavior. (I am running Blender from Steam.) I made sure when I began rendering that the blend was set for CPU rendering.          And to answer what @pycoder asked, yes, I am using Cycles Render.


What’s the difference between “from your lips” and “from your lips to God’s ears”?

I read in one website that the former is a short version of the later, but I found no other source saying so. Also, I know the meaning of the former, but I’m not sure what “from your lips” mean. Is it really just a shorter version? If not, then what does it mean?


What is the minimum time between UK toursit visas?

I want to stay in the UK for 6 months on a tourist visa. Then I will leave and return for another 6 months. What is the minimum time I must be out of the country before re-entering?


Double booked - User bookmarking question recorded twice

In this  one user is shown as having bookmarked  twice:  This doesn't appear to be the same question as:  or  though it's certainly possible that the cause is the same.


GNOME 3 merge top bar and Ubuntu dock (side/bottom bar)

Is there a way to merge to two bars in GNOME 3? Best case scenario would be to have one single bottom or top bar that has all the symbols on the left side and the rest like the time indicator, connections, on/off button, etc. on the right side.  Is that possible in any way?


Do any sea creatures exist in The Lord of the Rings?

Are there any water based creatures in The Lord of the Rings aside from the  who attacked the Fellowship in Moria?


How do I play local user-provided audio files on an Android or iOS device?

I'd like to allow a user to select a path to local audio files, in Android and iOS devices. Is there a way I could provide a list of available songs, in Android or iOS devices, so the user could pick and play them?


I was watching Episode 5 recently and something strange come to my eye. When Luke arrives at Dagobah it seems that neither Yoda and R2D2 seems to remember each other.   As far as I know R2D2 never had a memory wipe according to Star Wars wikis and this question:   I don't know if R2D2 knew Yoda personally but he should have known him. For Yoda it maybe was just another R2 unit.   Is there a universe (Legends or extended) explanation why R2D2 seem to doesn't know him?


How do we use myself as the only subject of a sentence?   For example I once heard some people saying Myself am to be blamed. Is this grammatically correct? How is it different from I am to be blamed?


How to make a shortcode for my WP_Query Loop?

I'm a noob Wordpress Developer and I just created my first Custom Template Page using Advanced Custom Fields and managed to loop.     <?php              $args = array(                 'post_type' => 'art',                 'orderby' => 'title',                 'order' => 'ASC'             );             $the_query = new WP_Query( $args );                  ?>         <?php if ( have_posts() ) : while ( $the_query->have_posts() ) : $the_query->the_post(); ?>           <?php get_template_part( 'content', 'art' ); ?>          <?php endwhile; endif; ?>   But I will like to use it not only inside a template page, but anywhere I want. Therefore I need to create a shortcode.  Example:  function foobar_func( $atts ){     return "foo and bar"; } add_shortcode( 'foobar', 'foobar_func' );   My question would be: How can i put the loop inside my shortcode?


Chart computation in weighted projective space

I'm confused about a relatively simple algebraic geometry computation. Let's take the affine plane curve $x^3-y^2=1$; this is an open subset of an elliptic curve. Indeed, if we embed affine space into projective space in the usual way, we get the genus one projective curve $x^3-y^2z=z^3$; so far so good. Now consider the weighted projective space $\mathbb{P}(2,3,1)$ with coordinates $x_2,y_3,z_1$. The affine chart away with $z_1=1$ is just the $(x_2,y_3)$-plane, so we can embed our above curve into $\mathbb{P}(2,3,1)$ via $x\mapsto x_2$, $y\mapsto y_3$; the completion inside the weighted projective space is then given by the homogenous equation $x^3_2-y^2_3 = z_1^6$. Consider now the affine chart $x_2=1$; this is the quotient by $\mu_2$ acting with weights $(3,1)=(1,1)$ on $y_3,z_1$, so its ring of functions is $\mathbb{C}[y_3^2,z_1^2,y_3z_1]$. Write $a=y_3^2,b=z_1^2,t=y_3z_1$, so that this ring can be written $\mathbb{C}[a,b,t]/(ab-t^2)$. Then the restriction of the complete curve $x^3_2-y^2_3 = z_1^6$ to the chart is given by $\mathbb{C}[a,b,t]/(ab-t^2,1-a-b^3)= \mathbb{C}[b,t]/((1-b^3)b-t^2)$. But now we see that this affine piece of the curve is cut out in affine $(b,t)$-space by the degree-$4$ equation $-b^4 +b-t^2=0$; it's easy to verify this is non-singular, so it's a Zariski open inside a smooth genus-$3$ curve. So the conclusion seems to be that the curve defined by $x^3_2-y^2_3 = z_1^6$ has a piece which is a Zariski open inside a genus-$1$ curve, and also a piece which is a Zariski open inside a genus-$3$ curve, which is impossible. What's going on?


Cannot connect to non standard port number with Windows command-line ftp (cmd ftp username not show)

I have a Windows 7 IIS - FTP Website on my localhost. Its IP is 192.168.2.77:15555,  I can successfully connect to ftp://192.168.2.77:15555/ and get the file list after enter username/password  through browser like Chrome.  But when I open cmd, and use ftp 192.168.2.77 or ftp 192.168.2.77:15555, the prompt for username/password does not show (which should show in normal procedure)  It changed to ftp> directly, and if I execute ls -al it tells me I'm not connected:  C:\Users\username>ftp 192.168.2.77:15555 Unknown host 192.168.2.77:15555. ftp> ls -al Not connected. ftp>     C:\Users\username>ftp 192.168.2.77 ftp> ls -al Not connected. ftp>   What should I do further to connect to FTP through cmd?


I am not sure if this belongs on Mathematics Stack Exchange, but it is somewhat relevant here.       The Problem If you've installed any graphing/plotting apps on your smartphone, you will notice that the app will only take the equation in form of a single variable for 2D (e.g  $y=f(x)$) or in 2 variables for a 3D plot (e.g $z=f(x,y)$). This is problematic as many equations are tough to reduce to the form of $y=f(x)$ or $z=f(x,y)$. The plotters like this because this is the only way they can plot it in form of lines connecting multiple points. These plotters compute the $y$ value at fixed intervals of $x$ and join the point to the previous one. The brute force approach to counter this is to check if the function satisfies it at each point on the image. The problem is that this not only takes more time, but gives discontinuous graph for the function as the image cannot have infinite resolution.         The Question The only way to fix this is to identify which point comes after the next in the plot and join them together by a line. That is where I am stuck. How do you identify which point is sequentially the next one for a given function? Keep in mind that for a human, this might be very easy to do. But, for a computer, this requires a general algorithm. Any ideas?


A sequence is defined recursively by $a_1=1$ and $a_{n+1} = 1 + \frac{1}{1+a_{n}}$.   Find the first eight terms of the sequence $a_n$. What do you notice about the odd terms and the even terms? By considering the odd and even terms separately, show that $a_n$ is convergent and deduce that its limit is $\sqrt{2}$.    EDIT: Ok, so I was being an idiot and forgot how to basic math for a little. The first 8 terms are as follows:  EVENS:  a2 = 1.5 a4 = 1.46666... a6 = 1.415731... a8 = 1.41426...   ODDS:  a1 = 1 a3 = 1.4 a5 = 1.4054... a7 = 1.41395...   From these I see that the even terms are decreasing while the odd terms are increasing. How can I use these to prove that $\{a_n\}$ converges? Does it have something to do with alternating series or something similar?


Don't allow questions that have the same title but different punctuation such as a question mark or hyphen

I was on Music, and I saw this question title:    I found a question it is apparently a duplicate of with this title:    If I were to ask a question called "What is concert pitch?" the system would stop me, as it would have the same title as another—I assume to avoid some obvious duplicates. However, apparently because of the lack of a question mark (), the newer question was able to be titled that.  If a question has a question mark or other punctuation as the only difference between its title and another, it should be treated as the same question title and not be allowed. This could stop things like if I tried to ask a question called "How do you conjugate the first-person imperative?" on Spanish and then change it to "How do you conjugate the first person imperative" (which ) to get it through, making an dupe and filling the review queues.


I have ubuntu 13.04 desktop installed and I've been reading about kernel 3.9s release yesterday. My issue is that I have no sound output with HDMI, something the new kernel apparently fixes. In reading, I've also come across kernels built for specific processors (I have an i5 on this laptop).  I guess my question is there a place to get this 3.9 kernel for my i5 processor for install in ubuntu?


How to prove that $m!n!(m+n)!|(2m)!(2n)!$ for every pair of positive integers $(m,n)$?

I want to prove that     For every pair of positive integers $(m,n)$, the statement $m!n!(m+n)!|(2m)!(2n)!$ holds.   which is equivalent to     For every pair of positive integers $(m,n)$, the statement $$ \sum_{i=1}^{\infty}\left\lfloor\frac m{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac n{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac {m+n}{p^i}\right\rfloor \le\sum_{i=1}^{\infty}\left\lfloor\frac {2m}{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac {2n}{p^i}\right\rfloor$$ holds for every prime number $p$.   I have tried setting $m=ap+c,n=bp+d$ with $a,b,c,d$ nonnegative integers and $c,d<p$. From that, the inequality becomes $$ a+\sum_{i=1}^{\infty}\left\lfloor\frac a{p^i}\right\rfloor+ b+\sum_{i=1}^{\infty}\left\lfloor\frac b{p^i}\right\rfloor+ a+b+\left\lfloor\frac{c+d}{p}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac{a+b}{p^i}+\frac {c+d}{p^{i+1}}\right\rfloor \\\le 2a+\left\lfloor\frac{2c}{p}\right\rfloor+\sum_{i=1}^{\infty}\left\lfloor\frac {2a}{p^i}+\frac{2c}{p^{i+1}}\right\rfloor\\+ 2b+\left\lfloor\frac{2d}{p}\right\rfloor+\sum_{i=1}^{\infty}\left\lfloor\frac {2b}{p^i}+\frac{2d}{p^{i+1}}\right\rfloor$$ $$\iff \sum_{i=1}^{\infty}\left\lfloor\frac a{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac b{p^i}\right\rfloor+ \left\lfloor\frac{c+d}{p}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac{a+b+\frac {c+d}{p}}{p^i}\right\rfloor \\\le \left\lfloor\frac{2c}{p}\right\rfloor+\sum_{i=1}^{\infty}\left\lfloor\frac {2a+\frac{2c}{p}}{p^i}\right\rfloor\\+ \left\lfloor\frac{2d}{p}\right\rfloor+\sum_{i=1}^{\infty}\left\lfloor\frac {2b+\frac{2d}{p}}{p^i}\right\rfloor\text.$$  After that, I tried splitting cases based on whether $2c\ge p$, whether $2d\ge p$, and whether $c+d\ge p$. The case where $2c<p$, $2d\ge p$, and $c+d\ge p$ becomes $$\sum_{i=1}^{\infty}\left\lfloor\frac a{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac b{p^i}\right\rfloor+ 1+\sum_{i=1}^{\infty}\left\lfloor\frac{a+b+1}{p^i}\right\rfloor \le \sum_{i=1}^{\infty}\left\lfloor\frac {2a}{p^i}\right\rfloor+ 1+\sum_{i=1}^{\infty}\left\lfloor\frac {2b+1}{p^i}\right\rfloor$$ $$\iff \sum_{i=1}^{\infty}\left\lfloor\frac a{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac b{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac{a+b+1}{p^i}\right\rfloor \le \sum_{i=1}^{\infty}\left\lfloor\frac {2a}{p^i}\right\rfloor+ \sum_{i=1}^{\infty}\left\lfloor\frac {2b+1}{p^i}\right\rfloor$$ $$\iff \sum_{i=1}^{\infty}\left( \left\lfloor\frac a{p^i}\right\rfloor+ \left\lfloor\frac b{p^i}\right\rfloor+ \left\lfloor\frac{a+b+1}{p^i}\right\rfloor\right) \le \sum_{i=1}^{\infty}\left( \left\lfloor\frac {2a}{p^i}\right\rfloor+ \left\lfloor\frac {2b+1}{p^i}\right\rfloor\right)\text.$$  How to carry on from there?


The largest value of $n$ such that $n+10| n^3+100$

If $n\in \mathbb{Z}$ and follow the property  $$n+10| n^3+100$$  then what is the largest value of $n$  Please help me to solve this!!!


How to protect SHTML pages from crawlers/spiders/scrapers?

I have A LOT of SHTML pages I want to protect from crawlers, spiders & scrapers.   I understand the limitations of SSIs. An implementation of the following can be suggested in conjunction with any technology/technologies you wish:     The idea is that if you request too many pages too fast you're added to a blacklist for 24 hrs and shown a captcha instead of content, upon every page you request. If you enter the captcha correctly you've removed from the blacklist.   There is a whitelist so GoogleBot, etc. will never get blocked.   Which is the best/easiest way to implement this idea?  Server = IIS    Cleaning out the old tuples from a DB every 24 hrs is easily done so no need to explain that.


Explain how (or if) a box full of photons would weigh more due to massless photons

I understand that mass-energy equivalence is often misinterpreted as saying that mass can be converted into energy and vice versa.  The reality is that energy is always manifested as mass in some form, but I struggle with some cases:  Understood Nuclear Decay Example  In the case of a simple nuclear reaction, for instance, the total system mass remains the same since the mass deficit (in rest masses) is accounted for in the greater relativistic masses of the products per $E=\Delta m c^2$.  When a neutron decays and you are left with a fast proton and a relativistic electron.  If you could weigh those two without slowing them down, you would find it weighed as much as the original neutron.  Light in a Box  This becomes more difficult for me when moving to massless particles like photons.  Photons can transmit energy from one heavy particle to another.  When a photon is absorbed the relativistic mass (not the rest mass) of the (previously stationary) particle that absorbs it increases.  But if my understanding is correct, the energy must still be manifested as mass somehow while the photon is in-flight, in spite of the fact that the photon does not have mass.  So let's consider a box with the interior entirely lined with perfect mirrors.  I have the tare weight of the box with no photons in it.  When photons are present the box has an additional quantifiable amount of energy (quantified below) due to the in-flight photons.  Say there are $N$ photons... obviously assume $N$ is large.  $$\Delta m = \frac{ E }{ c^2 } = \frac{ N h }{ \lambda c}$$  Interactions are limited to reflections with the wall, which manifest as a constant pressure on the walls.  If I hold this box in a constant gravitational field (like the surface of Earth) then there will be a gradient in the pressure that pushes down slightly.  Is this correct?  Wouldn't there still technically be mass as the photons are in-flight, which would cause its own gravitational field just as all matter does?  How is this all consistent with the assertion that photons are massless?  Is it really correct to say that photons don't have mass?  It seems to be a big stretch.  Please offer a more complete and physically accurate account of this mirror-box.


Proving image of $f:D^n\rightarrow \mathbb{R}^n \;$ contains $\;D^n$

Consider a closed disc $D^n\subseteq \mathbb{R}^n$ and let $f:D^n\rightarrow \mathbb{R}^n$ be a continuous map with $f|_{S^{n-1}}$ is the identity on the boundary of $D^n$. Prove that $D^n \subseteq \operatorname{Im}(f)$. Is my following argument correct? Suppose $x\in D^n$ and $x\not \in f(D^n)$. Then we have $\operatorname{id}_{S^{n-1}}$ factors through $f\circ i:S^{n-1} \hookrightarrow D^n \rightarrow \mathbb{R}^n-\{x\}$. Recalling the fact that $\mathbb{R}^n-\{x\}$ deform retracts to $S^{n-1}$, the contradiction here comes from applying the $H_{n-1}$ functor to obtain that $H_{n-1}(f\circ i):\mathbb{Z}\rightarrow 0 \rightarrow \mathbb{Z}$ is the zero homomorphism, certainly not equal to the identity homomorphism $H_{n-1}(\operatorname{id}_{S^{n-1}}):\mathbb{Z}\rightarrow \mathbb{Z}$. Hence $f$ must contain its image. Also is there a way to prove this directly? I think I can smell Brouwer's fixed point theorem and/or Borsuk-Ulam but I'm not sure how to employ it.


Photoshop. How to remove all white space, background + unenclosed space

Hi everyone here a problem I have,  basically I want to remove all white from this image so I can paint beneath the illustration.  When I remove the white using magic eraser or the magic wand I'm still left with loads of 'white enclosed spaces'   < this is my problem. It seems like I'll have to go into the image and use the magic wand individually for each white space?.  Is there an easier way to remove all of the white automatically?


I thought Mavericks was suppose to utilize RAM memory better, thus run smoother.  Running ML on Mac mini 2012, with 16GB RAM...always running smoothly even with over a dozen apps running.  Now, after installing Mavericks, my Mac is SLOW, eating up RAM like crazy! Looking over usage, of the 16GB of installed memory...on average it uses 10-14 GB RAM when barely running a few apps!!!   There is this kernel_task that is always running with over 1GB of RAM and most apps are not taking that much RAM, so what is using up all my RAM?! File cache? It shows very high in that new description, with about 1/3 of my total RAM


My collaborator added \usepackage[no-math]{fontspec} to a document we're working on. The result is that \_ underscores become v. long: cf. pictures below.   \documentclass{article} \usepackage[no-math]{fontspec} \pagestyle{empty}  \begin{document} \textrm{metric\_space} \end{document}   With fontspec:    Without fontspec:   The underscores are about twice as long with fontspec, and also much thinner. My question is, how do I get back to the original width? (Ideally I would like to preserve the thinness -- it looks much nicer than the original.)  In case someone asks, "why are you using \_?", the short answer is that I need to typeset identifiers involving an underscore. See  for an example in context. I'd be happy with using something other than \textrm, if it looks decent in the context of that example.


We (myself, wife and two children) are planning to visit UK in the summer (I have already started to regret it!!).   I have some visa related questions:   Does each applicant have to create their own login/password and create an application? Do minors need their own login/password and application ? do they need their own email address? Do I have to make four separate payments, one for each of us? If I submit four separate applications, what is the guarantee that I will get a same-day appointment for all of us. Obviously, I hate to make four separate trips to the interview center which means my wife and I have to take time off from work four times. Is the visa fee for children the same as for adults?


Is this inequality true? $ (x + y)^{\alpha} < x^{\alpha} + y^{\alpha} $, for positive $x$ & $y$, and for $0 < \alpha < 1$

If $0 < \alpha < 1$, then       $$ (x + y)^{\alpha} < x^{\alpha} + y^{\alpha} $$      for $x$, $y$ positive.   Is this inequality true in general?  I tried using Young's Inequality: For $z,t > 0$, and for $n$, $m$ such that $n+m=1$, then   $$ z^n + t^m \leq nz + mt $$  So, using this we have   $$ (x+y)^{\alpha} \cdot 1^{1 - \alpha} \leq \alpha(x+y) + (1-\alpha) = \alpha x + \alpha y + (1-\alpha)$$  which is not as tight as I want.


how to add android-studio/bin/ to my PATH environmental variable?


What command should I use in Linux to format completely as in Windows?

I would like to know if there is any command in Linux (Ubuntu, Linux Mint, etc) that is equivalent to the Windows full format option.


Do I need any article in the following case?

Today we've designed Unforgettable Day campaign. or Today we've designed the Unforgettable Day campaign.


Access a variable inside an asynchron function

I do have an asynchron function. In this function I need to have the value of an variable, which is defined outside the function. How is it possible to access the variable inside the asynchron function. Thanks for your help.   var valueTest = "Hello";  doUpdate(source) .then(myValue => {   // do something with MyValue is working   // How can I use the valueTest variable at this position?   // I need it in the function doUpdateTest   doUpdateTest(valueTest, myValue); })


Can I simplify or approximate this equation without sigma and combination?  \begin{align} \sum_{i = 0}^n (-1)^i {n \choose i} \frac{{d+1}}{d(di + 1)} \end{align}


Prepopulating fields of user edit form (also: passing {{user}} into a javascript function?)

Basically, I'm trying to make an edit profile modal with fields that are already prepopulated by the user's original data. I passed django models into my javascript files by using these brackets {{}} but it doesn't seem to work for {{user}} (as in request.user).   This is what I did for simple fields:
     Email     <input value={{user.email}} type="email" name="email" placeholder="Email">
   {{user.email}} successfully is set as the default value for the input.  Is there a different way to prepopulate fields? If there is, let me know and I might not have to deal with this next situation.   My naive solution works for text fields but if I have a multiselect like:
     Native Language         <select name="nativelanguage" id="nativedrop" class="ui fluid search selection dropdown">         <option value="">Language</option>         <option value="English">English</option>         <option value="Spanish">Spanish</option>         <option value="French">French</option>     </select>
   my solution no longer works. I want to pass {{ user }} into a javascript function like myFunction({{ user }}) but it seems that this is not possible.   Could anyone give me advice on how to prepopulate fields or fix the second issue below? Thanks!


My desktop shows docks on two positions, one on the right and one on the bottom of the screen, as shown in the screenshot.  How can I exclude the right one? The GNOME extensions that are currently active in my system are:  Dash to Dock  User themes


How can I compute the distance between two coordinates in TikZ?

Given two points (defined, for instance using nodes), I want to compute the distance between them.   Is there some build in functionality in tikz to do this? If not, how can it be done using the mathematical engine?   The application I have in mind is to draw an circular arc centered at (a) and passing through some second point (b), where only (a) and (b) are known.


node.js app on ubuntu linux with postgresql on virtual box on windows client

I set up, ubuntu linux on virtual box. Then I installed postgresql and node.js  So basically I made a clean installation and i want that  ubuntu handles my requests.  When i run node server.js , a Sequelize.js error occurred.   Unhandled rejection SequelizeConnetionRefusedError: connect ECONNREFUSED 127.0.0.1:5433  PostgreSQL is listening on port 5432, and once i run node server.js,tables are created with no problem.  I think is a problem with my client, and I don't know why.  postgres.conf listen_addresses='*'.  pg_hba.conf  host all all 0.0.0.0/0 trust.  I have little bit experience with Linux Ubuntu and configuration So a big hug and thanks for who will help me


"Stack-overview" a dashboard for cross site users

I have now signed up to the 4 sites and I am trying to swap between them easily.  In my usual slackness and developer mindframe I was wonding if there were any plans to have an overview for a person to see all their stuff across all the sites in one screen. A sort of mash up or web parts or something.


$G$ is Topological $\implies$ $\pi_1(G,e)$ is Abelian

Hypothesis: Let $G$ be a topological group with identity element $e$.  Let $\mu$ denote the multiplication mapping in $G$.  Goal: Show that $\pi_1(G,e) = \pi(G)$ is an abelian group via the hint below.  Hint: There are two products on $\pi(G)$.  The usual product $\circ$ defined for the fundamental group and the product $\ast$ induced by  $$ \ast: \pi(G) \times \pi(G) \cong \pi(G \times G) \overset{\pi(\mu)}{\rightarrow} \pi(G). $$  Show that there is a common two sided unit, $u \in \pi(G)$ for both products and there is a distributive law  $$ (f \ast g) \circ (a \ast b) = (f \circ a) \ast (g \circ b) $$  Attempt:   Suppose the distributive law in the hint holds.  Suppose further that $1$ -- the identity element in $\pi(G)$ with respect to $\circ$ -- serves also as the identity element in $\pi(G)$ with respect to $\ast$. Then for $a,b \in \pi(G)$, we would have the following relationship:  $$ (1 \ast a) \circ (b \ast 1) = (1 \circ b) \ast (a \circ 1) $$  so that  $$ a \circ b = b \ast a $$ Then if we can show that for all $f,g \in \pi(G)$ that $f \ast g \iff f \circ g$, we could complete the above relation to  $$ a \circ b = b \ast a = b \circ a $$  so that $\pi(G)$ is abelian as desired.   Question: Am I on the right track?


Show that series $\sum_{n=2}^{\infty} \frac{1}{(\log(n))^{\log(\log(n))}}$ is divergent

Show that series $$\sum_{n=2}^{\infty} \frac{1}{(\log(n))^{\log(\log(n))}}$$ is divergent . What inequality can we use here. i tried various method but none of these give any result. Any hint please .


Whatsapp, Keeping the number on the new phone but without the old sim card. Ok the situation is I love my old number and to be honest don't want to ask everybody to change my number again and again. But I do not have the old sim card, and that bums me out. If there is any way to achieve this?


Should I use a canonical link which refers to the current URL with pagination?

I know there are similar questions to this, but they either did not cover what I was looking for or I did not understand them fully, therefore I am asking this here.  My situation  At the moment I am using rel prev and rel next as pagination.  <link rel="prev" href="http://www.example.com/category/blablabla/page/2" /> <link rel="next" href="http://www.example.com/category/blablabla/page/4" />   I currently also add a canonical link which refers to the first page, i.e:  <link href="http://www.example.com/category/blablabla" rel="canonical">   The problem  The situation is like this:  The first page has only 20 items (as all other pages do).  With this canonical link i.e to the first page, only the first page gets indexed by Google.  I would like all the pages to get indexed because important content might get lost if they are not indexed.  Should I just change the canonical link to the current URL? i.e the current page, in this case:  <link href="http://www.example.com/category/blablabla/page/3" rel="canonical">   Or should I do something else, if yes, then what would it be?


How does the lift force of an airplane work?

At first I thought that the lift force of an airplane wing came from the buoyant force of the air. Thus we can calculate it's lift force using $$ F_b={\rho}gV$$   However, that does not seem to be true since this would yield a smaller number than the weight of the plane consequently the plane would be in free-fall which is not the case. Then I tried reasoning with Bernoulli's equation.  $$P_1+{\rho}gh+0.5{\rho}v_1^2=P_2+{\rho}gh+0.5{\rho}v_2^2$$ Where $v_1$ is the speed of the wind above the wing and $v_2$ is the speed below the wing. Now if I assumed that the thickness of the wing to be negligible I can simplify the equation as such  $$P_1+0.5{\rho}v_1^2=P_2+0.5{\rho}v_2^2$$  Algebraically moving things around  $$P_2-P_1=0.5{\rho}(v_1^2-v_2^2)$$ Lastly, using $\Delta PA=F$ $$(0.5{\rho}(v_1^2-v_2^2))*A=F$$ Where $F$ represents the lift force on the airplane wing. Can I set this F equal to ${\rho}vg$? Resulting in this $$(0.5{\rho}(v_1^2-v_2^2))*A={\rho}Vg$$ $$(0.5(v_1^2-v_2^2))*A=Vg$$ Would it make sense setting the lift force equal to the buoyant force? Since I keep thinking that it must be the buoyant force that lifts the wings. Otherwise there does not seem to be any other force that could hold up the plane.


I have a generic class that I'm trying to implement implicit type casting for.  While it mostly works, it won't work for interface casting.  Upon further investigation, I found that there is a compiler error: "User-defined conversion from interface" that applies.  While I understand that this should be enforced in some cases, what I'm trying to do does seem like a legitimate case.  Here's an example:  public class Foo<T> where T : IBar {     private readonly T instance;      public Foo(T instance)     {         this.instance = instance;     }     public T Instance     {         get { return instance; }     }     public static implicit operator Foo<T>(T instance)     {         return new Foo<T>(instance);     } }   Code to use it:  var concreteReferenceToBar = new ConcreteBar(); IBar intefaceReferenceToBar = concreteReferenceToBar; Foo<ConcreteBar> concreteFooFromConcreteBar = concreteReferenceToBar; Foo<IBar> fooFromConcreteBar = concreteReferenceToBar; Foo<IBar> fooFromInterfaceBar = intefaceReferenceToBar; // doesn't work   Does anyone know a workaround, or can anyone explain in a satisfactory way why I shuouldn't be able to cast interfaceReferenceToBar implicitly to Foo<IBar>, since in my case it is not being converted, but only contained within Foo?  EDIT: It looks like covariance might offer salvation.  Let's hope the C# 4.0 specification allows for implicit casting of interface types using covariance.


simple frontend with qml (for n2n client)

I am trying to write a simple qml application being a n2n frontend of the client and following the . This application is first intended for the desktop, but if it can also be used as a phone application for Ubuntu Touch, even better.  You can see the code hereunder, but since I am not really a developer, I have basic questions:   How can I execute a shell command in qml (the n2n programme is run in the terminal with the "edge" command + few parameters). How can I pass variable in this shell command to be executed? How to store the parameters in a configfile for the next time?   Thanks in advance for your help!  The code:  import QtQuick 2.0 import Ubuntu.Components 0.1 import "components" import Ubuntu.Components.ListItems 0.1 import Ubuntu.Components.Popups 0.1  /*! \brief MainView with a Label and Button elements. */  MainView { id: root // objectName for functional testing purposes (autopilot-qt5) objectName: "mainView"  // Note! applicationName needs to match the "name" field of the click manifest applicationName: "com.ubuntu.developer.No Launchpad user ID configured..n2nedge"  /*  This property enables the application to change orientation  when the device is rotated. The default is false. */ //automaticOrientation: true  width: units.gu(30) height: units.gu(50)  property real margins: units.gu(2) property real buttonWidth: units.gu(9)  Page {     title: i18n.tr("n2n edge")      Column {         id: pageLayout          anchors {             fill:parent             margins: root.margins         }         spacing: units.gu(1)          Row {             spacing: units.gu(1)              TextField {                 id: networkPwd                 placeholderText: "Password"                 echoMode: TextInput.normal             }         }         Row {             TextField {                 id: nodeIP                 placeholderText: "Node IP"                 echoMode: TextInput.normal             }         }         Row {             TextField {                 id: nodePort                 placeholderText: "Node port"                 echoMode: TextInput.normal             }         }         Row {             TextField {                 id: networkName                 placeholderText: "Network name"                 echoMode: TextInput.normal             }         }         Row {             TextField {                 id: clientIP                 placeholderText: "client IP"                 echoMode: TextInput.normal             }         }         Row {             Button {                 id: validatePwdButton                 text: i18n.tr("Validate")                 width: units.gu(12)                 onClicked: {                     cmdForm.update();                 }             }         }         Row {              TextField {                 id: cmdForm                 placeholderText: "sudo edge -a ClientIP -c NetworkName -k pwdForm -l NodeIP:NodePort"                 echoMode: TextInput.normal             }         }     } } }


Can I automatically save datetime for every entry in my spatialite tabel?

I'm using QGIS and SpatiaLite. Is it possible to store date and time in a field "datetime" for every entry automatically - maybe with some python code? Already existing datetime should not be updated.


Why did Palpatine choose Jango Fett's gene to create Clone Army?

The plan of Palpatine for Clone Army was to make it accepted by The Galactic Republic. Couldn't a Bounty Hunter's gene make it difficult? Also, what was the benefits of using Jango Fett's gene? Why didn't he pick any random guy instead of Jango Fett?


Include and work with flowcharts and diagrams in posts

I would really like to be able to include a wire frame in my posts.  I have a few questions that could really benefit from a flow chart, especially one that people could fill in as part of their answer.  Is there something out there like this (Mockingbird or Google docs plugin?)    If not, I think that Stack Exchange would really benefit from one. All that would be required is a site plugin that could read, render and edit XML code (for the diagram).  The diagram XML could exist in a special code section on any post or answer.  This code could then be copied, edited, quoted, etc. just like any other section on the posts.   Here is a great example of a diagramming system that saves and loads XML code:


Difference between fractions and rational numbers?

What is the difference between fractions and rational numbers? is $\frac{\pi}{1}$ a fraction?


I have two date strings in DDMMYYYY format. say startdate="18/02/2013" and enddate ="26/02/2013".  How can I compare these dates. I want enddate to be greater than or equal to startdate Thanks for Your Time.


Why $\cos a\cdot \cos b+\sin a\cdot \sin b = \cos (b-a)$

I do not get why  $$\cos a\cdot \cos b+\sin a\cdot \sin b = \cos (b-a)$$  Thank you for your help


i have that $H_p(X,Y)$ is isomorphic to $Z_p(X,Y)/(B_p(X)+C_p(Y))$, where  $Z_p(X,Y)=\lbrace \sigma\in C_p(X), \partial\sigma\in C_{p-1}(Y)\rbrace$  and i want to deduce that $H_0(X,Y)$ is the free module generated by the path connected components of $X$ that do not contain points of $Y$  but i don't know how to prove it ?  can someone help me ?  Thank you


Can a character move after using the Help action in combat?

If, say, a Fighter is engaged in melee with an orc, can the Cleric, starting 10' away from the Orc, move 5' toward the orc, Help the Fighter (to give him Advantage), then move away 25'? He would provoke an attack of opportunity, but would the Help action still work?   Put another way, do you have to be within 5' of the target when the Helped friendly creature attacks in order for it to gain Advantage, or only during your (Help) action?


Let $\langle G,*\rangle$ be an abelian group with identity element $e$. Prove that $H = \{x ∈ G | x ∗ x = e\}$ is a subgroup of $G$

Let $\langle G,*\rangle$ be an abelian group with identity element $e$.  Prove that $H = \{x \in G | x ∗ x = e\}$ is a subgroup of $G$.


I’m trying to duplicate the lower part of my mesh to the other side of the model. So I select it, and mirror it to face the correct way, I join the vertices on the model. Seems nothing is odd, but once I add the modifier, I get 2 jagged vertices appearing. I cannot figure where they’re coming from.  Thank you.


Why do some domains have a '/' at the end of the home page URL?

I am wondering why some websites have a / at the end of their URL, but others don't.  For example:   www.google.com/ but then www.khanacademy.org (No /)


What is a single-word to describe a person who refuses to apologize or admit when they're wrong, especially when dealing with others?

This is in regards to something objective that I am writing about unhealthy familial dynamics and how someone can move on in healthy ways. This is for a course I am taking.  What is a single-word to describe a family member who refuses to apologize or admit when they're wrong, especially when they've hurt or betrayed their family members? These slights could be trivial - hurt feelings, moderate - abuse/neglect, or extreme - criminal/exploitative.  Here are a few examples of each:   Trivial - A mother in her 60s hurts the feelings of her 40 year old daughter by calling her cute and/or adorable. Not only does the mother fail to notice that her daughter is hurt, but dismisses other people when she's told that her daughter was clearly hurt and that it's considered inappropriate to refer to someone in that age group as being cute or adorable. The mother immediately dismisses what is being said by stating that she didn't do anything wrong. When asked if anyone ever refered to her as being cute and/or adorable at 40 years old, she responds with no, but refuses to make any distinction. Moderate - A father continually calls his daughter fat. She develops issues in regards to her self-image and it has a negative effect on her overall mental health. She falls behind at school. When others attempt to intervene, the father refuses to hold himself accountable or responsible and continues calling his daughter fat, even when he's aware of the consequences. Child Protective Services are brought in and the girl is removed from the home. Extreme - A son uses his parents social security numbers to take out many large loans without their knowledge. He defaults on all of the loans, leaving his parents in millions of dollars in debt. He refuses to go forward and admit to the banks/federal agencies that he used his parents social security numbers without their consent, letting his parents take the fall.   I hope for objective answers.


Java null pointer exception. What is the error in my code?

So I am new into Java and android development. I know basic Java (abstraction, inference, etc.) and I was going through one of the books on android development. I was supposed to build a small quiz app that has a text field and 3 buttons (true, false and next question). I have 2 classes, one is a controller and the other is a Model class. The app doesn't agree to run and the most I can make out from Logcat is something known as a null pointer exception. It would be great if anyone could help  I followed the instructions but had made small tweaks, but since that didn't work I simply just copy-pasted. Still the program isn't running  The controller class:  @Override protected void onCreate(Bundle savedInstanceState) {     Button mTrue;     Button mFalse;      TextView question=(TextView)findViewById(R.id.question_field);     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      TrueFalse[] ind= new  TrueFalse[]{new TrueFalse(R.string.q1, false),             new TrueFalse(R.string.q2, true),             new TrueFalse(R.string.q3, true),             new TrueFalse(R.string.q4, true),             new TrueFalse(R.string.q5, false)     };      int mIndex=0;      int questions= ind[mIndex].getMquestion();     question.setText(questions);}`   The model class:  public class TrueFalse { private int mquestion; private boolean mtruefalse;  public TrueFalse(int quest, boolean mtrue){     mquestion= quest;     mtruefalse= mtrue; }  public int getMquestion() {     return mquestion; }  public void setMquestion(int mquestion) {     this.mquestion = mquestion; }  public boolean isMtruefalse() {     return mtruefalse; }  public void setMtruefalse(boolean mtruefalse) {     this.mtruefalse = mtruefalse; }   So the program was supposed to display the question in the text field as per the questions I preset on the strings.xml. I haven't hooked the next button as yet so that was nonfunctional. I have edited other attributes via the xml (which I don't think is a problem so I haven't put that up here).   Thanks


Why does the SARS-CoV2 virus not remain infectious forever? Or does it?

Given that the majority of biologists do not currently consider viruses to be alive, a virus can never die.  It can, however, get destroyed by long exposures to soapy water, alcohol, and apparently certain frequencies of UV light.  Why is an individual SARS-CoV2 virion not infectious forever?  Or is it?


Show when a post is in the process of being edited

My issue:  On this answer I dig in a comment and stated that the poster should add more than just a bare-bones code answer, then we got into a little chat about Impatience and editing, as should be exampled by the link.  What this brings up to me is it would be very, very helpful to have a small note on a post that when I load a question (and answers) on a page that I can see a flag marker that the Q or A is currently being edited.   Who by and the details of the edit are not needed, simply the fact that someone has the question open as an edit and that I can wait a few minutes to see the additions before posting my comments or scoring based on the pre-edit condition of the post.  This is not the same as  where the answer  is a good answer, but the answers core reasoning only applys if the information is given in the context of a parallel edit.     All the topics on META that I've found about this seem to be based on parallel edits and on people editing posts at the same time needing to know if someone else is, I think that bare if at all croses over to this where I think a comment or a vote on a question/answer can be better saved/posted if they knew that the question/anwser was currently being edited.      This is not a duplicate post of     That post is all about parallel editing this is about informing readers that a post is being edited. There is a crucial difference here.


How do you keep user.config settings across different assembly versions in .net?

Basically the problem is that each time the assembly version changes (i.e. the user installs a new version of the application) all their settings are reset the the defaults (or more accurately a new user.config file is created in a folder with a different version number as the name)  How can I keep the same settings when upgrading versions, since using ini files or the registry seem to be discouraged?  When we used Clickonce it seemed to be able to handle this, so it seems like it should be able to be done, but I'm not sure how.


I am working through a statistics course right now and struggling a lot with this question. I'm not really sure where to begin.  Any reading or idea where I should begin? I really need to understand this and I just dont.


Where was this photograph used as a Windows 10 wallpaper taken?

The photograph below is available as a wallpaper in Windows 10. Where was it taken?


How do I make one bone that controls the entire rotation and movement of the armature? (or do I need to do that?)

I'm currently using Megaman from Legends to study rigging. The bone that I have selected above, I want to use to control the rotation and movement of the entire armature for animation. Now my question is this - do I need a bone to control the rotation and position of the armature with a bone (and how do I do that?), or should I just control the rotation and position of the armature in object mode? Please note: I will be making a game (with a separate original character), so I will need the animation to transfer nicely into Unity.


Just tried some approach (Stolz-Cesàro theorem and sandwich theorem) can't prove this equation $$\lim_{n \to \infty}^{}\frac{\sum\limits_{k=1}^{n}k^{p}}{(n+1)^{p}} =\frac{1}{p+1}$$


How to assign a path variable on a bash file?

I need to create a bash file that automatically makes new directories and assign some of them to a variable. I can make folder without problems but when I test variables with echo the console return me nothing: #!/bin/bash  mkdir ~/Scrivania/TEST2/Salmonella_enterica mkdir ~/Scrivania/TEST2/Salmonella_enterica/NCBI mkdir ~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2 mkdir ~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Annotation mkdir ~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Sequence mkdir ~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Sequence/Chromosomes mkdir ~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Sequence/WholeGenomeFasta CHR="~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Sequence/Chromosomes" ANN="~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Annotation" WGF="~/Scrivania/TEST2/Salmonella_enterica/NCBI/vs2/Sequence/WholeGenomeFasta" cd ~/Scrivania/TEST2  When I try to assign the variable directly from terminal it works perfectly (copy-pasted from the script, so no typo), it just does nothing when i execute the .sh, except creating folders. Thanks, i'm sure it's a stupid question but I never used bash files before.


The name of the last one should be NOT "Butterknife". Very minor issue, I know ... ;)     App version: 1.0.85 Device manufacturer: Xiaomi Device model: Redmi Note 3 OS version: 5.1.1 (V7.3.6.0.LHOMIDD)


Inequality in three variables $a,b,c$ given $abc\geq 1$

Let $a,b,c$ be three real positive numbers such that $abc\geq 1$. Prove that $$\frac{a}{b} + \frac{b}{c} +\frac{c}{a} ≥ \frac{1}{a} + \frac{1}{b} + \frac{1}{c}.$$   Here's what I have done. The expression is equivalent to  $$a^2c+b^2a+c^2b \geq  ab+bc+ac .$$  Denote $f(a,b,c)=a^2c+b^2a+c^2b-(ab+bc+ac)$. We need to show that $f(a,b,c)\geq 0$.   By AM-GM, $a^2c+b^2a+c^2b \geq 3$ (Given, $abc\geq 1$). By AM-HM, $(a+b+c)(1/a +1/b +1/c)\geq 9$ by AM-GM, min value of $a+b+c=3$ so $1/a + 1/b + 1/c \geq 9/3=3$. Thus, The minimal value of $f(a,b,c)$ is equal to the min value of $a^2c+b^2a+c^2b$ minus the min value of $ab+bc+ca=3-3=0$.  Please let me know if there is fault in argument.


Why is the speed of light exactly $299,792.458$ m/s and not faster or slower?

Why is the speed of light $299,792,458$ metres per second, and not faster or slower.  Why not $500$ trillion kilometers per second or $120$ miles per hour?  This has been 'bothering' me for a while. Googling it usually found answers about why isn't '$c$' infinite et cetera, and the answers were usually saying (from my interpretation) that if $c$ were infinite, then matter couldn't exist.  I recently found , but despite its blatantly obvious attempt to explain to laymen, I still don't understand why $c$ is (roughly) $300$ million meters per second.  A 'dummy's' guide to my understanding why '$c$' is the number/speed that it is, would be greatly appreciated by me and all others who will read your answer in the future.


What is the origin and use of "remember me to her/him"?

Is anybody familiar with the use of remember as in remember me to her/him?  I think I've see it in 19th century literature.  Most likely it's archaic.  I believe the speaker is commanding someone to give somebody his regards, or say hello.  It seems awkward to hear it now as we only use remember in the imperative to remind someone of something, as in, "remember to walk the dog".  Where does this use of remember come from and is it out of use?


Least upper bound on set of positive semidefinite matrices

Short version: Does the Loewner order have the least-upper-bound property? Long version: Suppose I have a finite set of finite-dimensional positive semidefinite matrices $\mathcal{M}$. That is, we have $M\ge 0$ for all $M\in\mathcal{M}$.  Here "$\ge$" is the , which is a partial order on matrices where we say $A \ge B$ when $v^*(A-B)v \ge 0$ for all vectors $v$ (and where "${}^*$" is the adjoint). An "upper bound" on the set $\mathcal{M}$ is a matrix $A$ satisfying $A \ge M$ for all $M\in\mathcal{M}$. For any set $\mathcal{M}$, is there necessarily a matrix $\bar{M}$ that provides a least upper bound in the sense that $\bar{M} \le A$ for all upper bounds $A$? It seems relevant that the space of upper bounds is convex, i.e., if $A$ and $B$ are upper bounds then so is $C_\lambda = \lambda A + (1-\lambda)B$ for any $\lambda\in [0,1]$.  However, it's easy to check that for any two upper bounds $A$ and $B$ there need not be a choice $\lambda$ such that $C_\lambda \le A$ and $C_\lambda \le B$.


Prove that this number is divisible by 7

Without using induction, how can it be proved that 7 divides $3^{2n+1}+2^{n+2}$ for each $n\in\mathbb{N}$? I tried to expand it using $\frac{x^{n+1}-1}{x-1}=1+x+..+x^n$ but I had no success. It would be great if more than one proof is provided.


When do player characters leave turn-based action (i.e. initiative order) if they are in a hostile area?

In most circumstances, it is easy to determine when turn based combat ends:   One side is completely killed, unconscious or has fled All parties declared truce   But when in a hostile area, like a Dungeon, do you end turn based action after each chamber with an encounter or do you stay in it for the whole crawl?  This is relevant because there are various effects in the game where you gain a bonus each time you roll initiative or depending on whether an enemy already acted.  As an example:  When you are in a dungeon or building completely filled with enemies and the PCs just cleared a room from enemies, but they don't know whether there are enemies in the next room and if there are whether they have noticed the sounds of battle.  Do you keep them in round based action, because maybe the door opens and enemies enter? Or do you leave it and possible give away that there is no nearby danger or have to reroll initiative when enemies enter the room (and give them the corresponding bonuses).


What is the emotion for being glad of someone getting their just deserts

Is there a word for the feeling of satisfaction when someone 'bad' gets punished? For example, when watching a movie and seeing the villain finally get defeated, the audience feels a sense of... what?  I thought I've heard of this word before but I can't find anything. Schadenfreude is a bit off and doesn't cover the "good, that guy finally got what he deserved" feeling (there's also a sense of moral superiority involved, I suppose?). I also found vindictive, but that doesn't convey the sense of satisfaction.


What does the "fast forward" mission feature in Borderlands 2 do?

Can anyone explain what this fast-foward prompt means?  I jumped in on the BNK-3R quest of "Where Angels fear to tread" with friends in co-op before I got to that point in my own game.  When I accepted the quest for "Angels" from Roland it prompted me to fast foward through parts of the mission i already completed.  I said yes but I don't understand what saying "yes" did and if i should say "no" in the future.


Opinions on the lack of private messaging

Foreword: Firstly I would like to state I am not requesting this feature be added. I am not foolish enough to believe that yet another person asking for it will have any impact on its implementation. Instead, I opt to ask people's opinions on the matter, find out what peoples' reasons are for wanting or not wanting such a feature.  Background: I'm a reasonably active StackOverflow user, I ask questions when I get stuck, I answer questions when I get bored. Recently I found a question from a person that obviously didn't quite understand the way SO works, he was asking for some suggestions on how to learn a specific language and better his programming skills. Unfortunately his question got put on hold, and long story short it got me thinking just why there isn't a private messaging system. So I looked here in meta and the continual debate, but I didn't feel any of these questions were actually targeting people's feelings about such a system, they were all asking to implement it or asking why it isn't implemented - not explicitly asking people's opinions on the matter. So, I'm asking now.  Question: What are your opinions on the lack of a private messaging system?  Do you like it because you like the disassociation and believe that SO serves well as a "programmer's wiki", or would you rather a messaging system be implemented despite accusations that it would drag SO down and make it more akin to a forum or social network?  Discuss.


Why isn't my Minecraft LAN server working?

My LAN server won't let my cousin join me or me join my cousin. It won't show up on the multiplayer screen - it keeps saying "scanning for LAN servers" but it never finds it. I am at his house and we use different computers but it won't connect. How can I fix this?


Partitioning a number into set of coprimes such that their product is maximum and sum of partition is the number itself

Example 1) Let the number be 7. Then we have a set {3,4}, so the product of the numbers is 10 and the numbers are mutually coprime.  Example 2) for n=12, coprimes set = {3,4,5}, where product is 60 which is maximum.  Example 3) n = 9, coprimes set = {4,5}, product is 20 which is maximum product.


Please. I am trying to understand the proof, that cdf of minimum of $n$ random variables is $1-[1-F(x)]^n$  If I have $n$ independent random variables $X_1, \dots, X_n$, all of them have the same CDF $F(x)$, what is the point of searching for the $\min=\{X_1, \dots, X_n\}$? Shouldn't $X_1, \dots, X_n$ have the same value for every x? (In the meaning: $P (\min \{X_1, \dots, X_n\}≤x) = P (\bigcup_{i=1}^n X_i\}≤x) \cdots$)  Thanks.


Good day! I am having a problem wherein fire does not render. I followed a . Followed everything in his tutorial. However, the fire in my scene does not render at all. I wanted it to look like rocket thrusters. As of now, this is what I currently have for my Smoke Domain material.  I temporarily set the smoke to 0 because it may be blocking the flame. I've provided the screenshots where the smoke is enabled and disabled. (Forgive the quality of the rendered images, I lowered down the samples to quickly render the image.  And for my scene, this is what it looks like.  I am rendering it using GPU compute. If there's anything missing in the  current scene setup, just ask for it and i'll provide the necessary requirements. I tried searching for solutions but nothing worked out for me. Thank you and have a nice day!


Does my machine support ? I found  where the list contains the required hardware requirements. Please find the below screenshots of few of my machine. Does any one of the below support OpenCL?  Screenshot from machine 1:    Screenshot from machine 2:    Screenshot from machine 3:    Does any of my three machines support OpenCL? Or do all the three support OpenCL? I am trying to run a basic OpenCL face-detection program and am failing. I have posted Stack Overflow question  regarding the same.  After running , the "1st machine" is of type GPU 1: Intel HD Graphics 2000. Does it support OpenCL?


Usage of "%"  I'm almost positive it's a prepositional phrase since it's really means "per cent" or "per 100".  So in a sentence like:     90% of my street are doing lawn work.   It would be "are" and not "is" because both "%" and "of my street" are prepositional phrases and therefore cannot contain the subject.  Am I right?


rename middle name of multiple files using bash

I've multiple files located in /opt/rec/ which I want to rename only some part of it using bash.  Original file name:  WK6LZTPR99999999_dig_2017-07-10 01:55:57.xy   which I want to change all files with in that directory as:  WK6LZTPR99999999_cur_2017-07-10 01:55:57.mp3


I have recently had a logo designed for my company only to realise after rebranding my vehicle and website is shares certain similarities with another well-known logo. Could somebody with a better understanding of what is legal and what not be able to help me out?  Our logo    The well-known logo


Why does the electric dipole moment of the electron tell us about its sphericity?

There are a bunch of experiments that claim to show that the electron is highly spherical by measuring the electron electric dipole moment. See e.g.:       However, according to the Cartesian expansion of a charge distribution (see ), if we assume the electron is made up of two small balls of negative charge $q$ separated by a small distance $2\mathrm{d}z$, and calculate the dipole moment in the centre of the two balls, the dipole moment is zero.  $$(-q)(-\mathrm{d}z)+(-q)(\mathrm{d}z)=0$$  which means even a highly non-spherical shape produces a dipole moment of zero.  So if the dipole moment is measured to be tiny, why does that imply the electron is highly spherical?    Some similar questions on this site:    is a different question because I am not asking about the mass distribution, I am asking about how the dipole moment in a Cartesian expansion tells us about the sphericity of the electron.  is also not what I am asking; I am asking why it is that the dipole moment can be used to tell you that the electron is spherical when in the example I give of a non-spherical object, the dipole moment is zero and is therefore not a measure of the degree to which the electron is spherical.


I recently failed an audit in the queue for auto-flagged low-quality posts.   Side question: can I somehow look that failed audit up to post the details here? In the meantime, I will recite from memory.  I pondered a while over the question because it was just a one-liner with a link attached. Basically, it read "use capital Y instead of non-capital y in your format string. You can find an explanation here: tutorial-link".  Although I did not know the language, the question was about date formatting and it does indeed work that way in languages I do know, so it looked ok, content-wise. If it were not ok for that specific language, that should have been a matter of voting/commenting, not closing/flagging.  Considering the answer would still provide help even if the link went dead, I think it was an edge case for link-only, but still ok. Certainly not the best answer I ever saw on SO, but not worth deleting either.  When I clicked "Looks good", I was greeted by the "you failed" message, telling me that the answer was deleted for "abusive language and spam". Abusive language and spam? Who did that? That's way off. And who decided this would make a good audit?  I never actually followed that link, maybe it did redirect to spam. If it had been flagged for spam I would have checked, but in the context of low-quality, I do not actually follow every link just to make sure it actually leads where it seems to lead.  There are a lot of other threads about auditing audits and I voted on them.   But after reading the other threads, I still wonder: who decides what makes a good audit?


What is the danger if a non-prime is chosen for RSA?

I was reading  about generating primes for RSA keys. The answers point out that most implementations of of the algorithm use probabilistic prime-ness checking algorithms.  by  made the most sense to me:     That is, if the test uses a randomly-chosen value (the "witness") which serves as the basis for the test. If the test passes, then the number is probably prime, but possibly not. We can repeat the same test with a new "witness", and if the test passes again then we have increased our certainty. We can continue to re-test as many times as we want until we've reached the level of certainty that we need.   This (and the other answers) heavily imply that we're never actually 100% certain that the numbers we've chosen for a key are actually prime.   Do any implementations follow up the probabilistic prime checks with exhaustive checks? I'm guessing not, because RSA key generation has to be pretty fast (compared to the heat death of the universe) to be useful. What "level of certainty" do we "need" for RSA keys? Is this an actual downside? If a non-prime number is used in an RSA key, to what degree would the search space of a brute force attack be decreased?  I'm torn on this, because as I understand it, a brute force attack relies on factoring the key, which is difficult for the length of numbers we've chosen. If we're 99.99...% certain a number is prime, then the most likely thing we've done is selected a number that's a product of two or more reasonably large primes. That would imply that the brute force attack is only a few orders of magnitude easier to conduct; according to , the RSA algorithm has orders of magnitude to spare. Are there better attacks that will succeed in much less time that could work by assuming one or both of the secret numbers are non-prime? Even if this is one-in-a-billion chance, if the attack is fast enough, it seems like its worth it.


Why is Janeway an Admiral and Picard is not?

Checking out  on Memory Alpha, I see that she had her first assignment sometime in the 2350's.       She was promoted to Admiral shortly after Voyager's return home, which was in 2378.   Now,  on the other hand, had his first assignment in 2327. He was then ordered by Admiral Janeway to Romulus in 2379. Is there any canonical reason why Picard never became an Admiral?


How to fix a downloads directory in UBUNTU 18.04?

I lost the downloads directory by mistake. Updates did not replace it. I do not want to reinstall UBUNTU as a solution to fix this issue. I am using UBUNTU 18.04. I get a message asking me to use blueman-services to configure a downloads directory but I couldn't. Is there a solution other than reinstalling UBUNTU?


I realised, reading another Phys.SE question about  that I don't really understand how  works. Particularly concerning, for a SCUBA diver.  The top answers to that question seem to claim that balloons get their "sense of down" from a pressure differential. They continue: when a car accelerates, the air at the back of the car becomes more dense, and at the front less dense, changing the plane of the pressure differential and so also, the balloon's sense of up. I find that extremely hard to credit. However, I realised that I don't really know why less dense things float in more dense things.  I'm fairly sure it's something to do with displacement of heavier things by lighter things, and I think pressure acting on the lighter thing's surface has something to do with it, but that's about it.


Unable to create bootable usb in Ubuntu 16.04

I'm trying to convert a Windows 7 iso file to bootable usb through Startup disk creator.  Startup disk creator not detecting my Windows 7 iso file.  But it detacts my Ubuntu iso file.  Note: It not detecting any windows iso's. But it detects all Ubuntu iso's.  Any restrictions with iso file name..?  Any help would be appreciated.


How to remap the Shift key to Caps Lock key

I have a minilaptop which shift keys do not work. I want to remap the layout so when I press CapsLock key it behaves like shift. I have seen many turials on this matter but most of them are either too broad or too specific, and I have not been able to solve this problem.  My minilaptop runs Ubuntu 18.04 with the LXDE desktop.  Edit: issue solved!  Answer below.


What is Catalina (and no other OSX) doing with/to the disk?

My question is at  Tetsujin closed it pointing to  but just look at the very different O.S.s in the two questions. Also, my question is vastly different in that I have expressly identified that the Case of the Vanishing Disk-Space is solely attributable to Catalina as no such thing was happening in Sierra, and there are also further particulars stated in the question. In one line, What on earth is Catalina doing with and to the disk that other OSXs didn't? With due respect to 'One-Percenters' of apple.stackexchange, please try to read and understand the question and its specifics and don't keep being so trigger-happy in shutting down questions/threads/discussions.


don't know the equation of the function but want to plot it

I know how to plot a function if i know the equation but in this case i don't know the equation of itself , thus i want to plot it by using some curve or approximation command     thanks for the help


Transcendental numbers involving primes?

Is the  value  $$ P(2)=\sum_{p \in \mathrm{primes}} \frac{1}{p^2} = 0.452247420041065498506543364832247934173231343\ldots $$  a transcendental number ?  What about the following sum ? $$\sum_{p \in \mathrm{primes}} \frac{1}{p^p} = 0.2873582513062241797364180458789322069559088\ldots $$  For the last sum,  might help because of the fast converging series.  The first sum might have been checked, as it is natural to come to such a sum. Perhaps, it is at least known if it is irrational.


How to "compose" a number knowing its bits value in C/C++

I want to compose a 1-byte (unsigned char) number, knowing its bits value.  For example, 7th and 6th are always 0 and 1 respectively, values of 5th to 3rd are stored in three other variables, and 2nd to 0th bits shall take a value stored in one variable, e.g. decimal 5.  At first I fought I can create an array of 8 elements, to store each bit, then convert it to a decimal number using custom bin2dec, but the problem is 1) I don't want to use additional "self-written" functions, 2) I'm not sure, how to put value 5 there (it looks like I need to dec2bin at first).  I can solve this problem using SystemC, but I'm interested how to do it using C/C++ methods (without additional downloaded libs).


I recently installed DataGrip from JetBrains, I extracted in /usr/local/share and I added into my ~/.zshrc to execute from the terminal like this  DATAGRIP_HOME=/usr/local/share/DataGrip/ export PATH="$PATH:~/.local/bin:$DATAGRIP_HOME:$DATAGRIP_HOME/bin:$JAVA_HOME:$ACTIVATOR:$ACTIVATOR/bin:$SCALA:$SCALA/bin:$TMUXIFIER:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"   Every time I execute datagrip.sh the proccess keep attached into the terminal and I get all the log of the application  which is the way to detach it?


Exam question: Showing $z = \left(\frac{1 +z}{\left|1 + z\right|} \right)^2$ for $z\in\mathbb{C}$ and $\left| z \right| = 1$

The following was a midterm exam question in an abstract algebra course I was not able to solve:     Let $z \in \mathbb{C}$ with $\left| z \right| = 1$ and $z \neq -1$.   Show that the following holds true:      $z = \left(\frac{1 +z}{\left|1 + z\right|} \right)^2$      Hint: This is a possible definition for a "principal root" of $z$.   In the exam, I tried to attack this using the fact that if $\left| z \right| = 1$ holds true, I can write $z$ as $\exp(it)$ for some $t\in \left[0, 2\pi \right[$. I tried to work on the left side of the equation using the properties of $\exp$, but didn't know how to deal with the norm in the denominator.  In hindsight, how can this be solved? Is the hint actually helpful?


I am using C and I am trying to write a small game. But I need to read the input whenever the player tabs on a key (say s), and the program does something, without pressing the enter.  I have seen many posts answering this, but they all use getchar() or getch() from curses or conio.h in Windows. But that's not what I want. The result can definitely done because of 2 examples:   vim when the user tabs on the :, it will immediately turns into the command mode to let you type in the commands. the readcommand in bash, whose -n${number_you_want} parameter can limit the chars it reads without enter.   But I wonder how they can do this even I already have the source of the functions in the examples. I still can't figure out how they do this. The source code of vim's  from getchar.c and the read command from bash source .  Can anyone help me explain how they works? Thanks in advance.