Suppose, I somehow happen to dig a hole diametrically through the Earth (neglecting all constraints like molten core etc ) ... and I throw an object from one side of the hole, will it reach the other end?

...And you jumped in.  What would happen when you got to the middle of the Earth? Would you gradually slow down, until you got to the middle and once you were in middle would every direction feel like it was up?


How to calculate $$\sum_{n=1}^{\infty} \frac{1}{(a+n)(b+n)}$$ where $0 <a,b< 1$?

How can I find the value of the series $$\sum_{n=1}^\infty \frac{1}{(b+n)(a+n)}$$ where $a,b\in[0,1)$?  It is obvious by standard arguments that the series converges, but how can I derive the explicit value dependent on $a$ and $b$.  Thanks  EDIT: $a,b$ can be assumed to be different.


When I review my reputation activity, I can see where I have downvoted posts & lost reputation. When I display the details asssociated the number matches the loss initially displayed    I noticed for one post I had a loss of 2 reputation but when I clicked to view the details it showed a gain of 2 reputation for an edit I had made.    How should I interpret this and/or how did this occur?

I found something in my reputation history that I cannot explain. Could someone please put some light on this?  According to this log, 25+10=36


I'm totally new to jQuery so I might've missed something here. Let's say the html looks something like this:

       text

       text

       text

       text

       text

       text

   I'd like to be able to access each "message" div within the scope of the "child" div, instead of just using this to iterate through each "message" class element:   $('.message').each(function(index, e) {});   I understand that I can get each jquery object using this, but want to then filter through using the code above to get each text within the scope of its parent class.  var message = $('.child');

I have a layout similar to this:

   and would like to use a jQuery selector to select the child img inside the div on click.  To get the div, I've got this selector:  $(this)   How can I get the child img using a selector?


Is it true that $(\mathbb{Q},+) \simeq (\mathbb{Q}^*_+, \times)$? If yes then is there any constructive isomorphism?

A question that may sound very trivial, apologies beforehand. I am wondering why $( \mathbb{Q}_{>0} , \times )$ is not isomorphic to $( \mathbb{Q} , + )$. I can see for the case when $( \mathbb{Q} , \times )$, not required to be positive, one can argue the group contains elements with order 2 (namely all negatives). In the case of the requirement for all rationals to be positive this argument does not fly. What trivial fact am I missing here?


The recent license posts  and  generated some confusion over the interpretation of the voting under the first feedback question, resulting in some potential misunderstandings complained by  and  answers, requiring  and  reviews.  I am not a licensing expert, so, personally, I upvoted the question at first because I thought it was a good change (and a good topic to discuss), but after reading the answers disagreeing with the proposal, I changed my opinion, and wanted to disagree and downvote it, but I couldn't change my vote right after that since I had already voted and the question hadn't changed.  Moreover, I thought it wouldn't matter much, since I still agreed that the question was important regardless of my agreement with the proposal, so the upvote would still represent my intent. Many of others also thought that way, and it kind of created a false-positive voting feedback.  That's reasonable, because our current guideline leaves two open interpretations: vote for well-written, and vote for agreement or disagreement, as we can see in the  (italic emphasis mine):     Voting is different on meta sites      Your Meta Stack Exchange account functions like an account on any   other Stack Exchange Q&A site: your reputation score goes up when   others vote up your questions and answers, and you earn badges for   your activity here.      For most posts, votes reflect the perceived usefulness: well-written,   well-reasoned, and well-researched posts tend to get more attention   and more upvotes.      Unlike normal Stack Exchange sites, meta invites the community to   discuss, debate, and propose changes to the way the community itself   behaves, as well as how the software works. On posts tagged   , voting can indicate agreement or disagreement with   the proposed change rather than just the quality or usefulness of the   post itself.   Another point is that the first post was actually migrated from , which allowed anyone to give a real feedback regardless of reputation, but the migration prevented a lot of users to give a negative feedback properly (or, as you possibly were expecting), as we can notice ,  (deleted), and .  Those are just examples of how the feedback questions have currently a bad mechanism. It should be clearer if the question voting represents or not the voter acceptance and agreement. I guess that the default behavior is that is doesn't, and if it actually does, we are not aware of it! And worst: we can't freely vote in it, since it requires 125 of reputation here (and not in any of the network-wide sites), blocking users to demonstrate their feedback (such issue is well discussed at ).  We know that something simple like the community wiki checkbox that changes some behaviors or something separated like the elections were successful enhancements for their unique needs.  I guess we have solid indicators that it is time for to enhance the voting mechanism intended for getting community feedback. Just to explore some possible solutions:   implementing a new way to vote; tuning Meta's privileges reputation; updating Meta's Tour and other guidelines to be clearer; other.    What do you think?

To make your opinion known on MSE you need both up and downvotes. Given at the moment you need 125 rep to downvote on this site, the voting patterns will be skewed positive because not everyone is active on the site.   This is to be expected for regular Stack Exchange sites as you are expected to be involved in the community before you are deemed knowledgeable enough to be part of the community voice. However, MSE is different because you are voting for the entirety of the Stack Exchange network and you shouldn't need to be active on MSE itself to have a voice on changes to the entire network.  This is especially important for questions like  because it will effect every network to do with coding at all. This was brought up in .  I would suggest reducing the rep required to downvote on MSE down to 100 (or 101) rep. This is the amount you get for the site association bonus. This is given once you achieve 200 rep on any network site and shows that you are active in at least one community. I think this would be the perfect use of the association bonus in showing that you are a member of the Stack Exchange community.


Let $a_n,b_n>0$ for all $n\in\mathbb N$.  Prove that  $\limsup (a_n b_n ) \leq \limsup a_n \cdot \limsup b_n$  I know that $\limsup (a_n+b_n ) \leq \limsup a_n + \limsup b_n$. But I don't know how to use this to get what I want to show.

I´m not sure how to start with this proof, how can I do it? $$ \limsup ( a_n b_n ) \leqslant \limsup a_n \limsup b_n  $$ I also have to prove, if $ \lim a_n $ exists then: $$ \limsup ( a_n b_n  ) = \limsup a_n \limsup b_n  $$ Help please, it´s not a homework I want to learn.


When creating a user defined exception What is the best practice, should the exception be created as checked or unchecked ?  I know unchecked/runtime exceptions need not be handled in the code.

In Java (or any other language with checked exceptions), when creating your own exception class, how do you decide whether it should be checked or unchecked?  My instinct is to say that a checked exception would be called for in cases where the caller might be able to recover in some productive way, where as an unchecked exception would be more for unrecoverable cases, but I'd be interested in other's thoughts.


Similar questions have been asked here before, for example , but my point is slightly different. I have absolutely no issue with the total number of SE sites, on the contrary. However I don't think it makes sense to split topics if there is a high correlation between the users interested in these topics. Here is an example which I personally find a bit annoying:  The Stack Exchange site which I find most helpful and in which I am most active is Stack Overflow. Now as a professional software developer I am not only interested in coding issues but also in topics like project management or requirements engineering which become more and more off-topic in Stack Overflow.  To ask or answer such questions, I need to go to other sites like Project Management or Programmers. Especially the boundary between Stack Overflow and Programmers is far from being obvious.  I would find it much more convenient to have all software development related topics on one site. Of course this is my personal opinion but many questions, answers and comments give me the impression that lots of other users have the same issue.  Am I missing something?

I was just thinking that maybe if we have more Stack Exchange websites then each person would be a member of more different sites on average. Since the time a person can spend online on average is limited it means he will be spending less time on each website. But would this affect the quality of these websites? I'm not talking only about the quality answers given but also the number of answers given, the promptness. Won't these things go down?  I think that the rate of questions won't go down much because you need to know what you need to know. However, the average time a person spends browsing through these websites (and chances upon a question he can answer) would decrease. So are we creating too many different Stack Exchange sites?


A few people have already asked the question of how to increase the maximum memory LaTeX is allowed to use (see  and ) because it is quite common for LaTeX to run out of memory when using, for example, pgfplots to plot experimental data.  Following the instructions from , I managed to successfully increase the memory limit. However, I was not able to increase the limit to an amount capable of processing a 10,000-data-points plot. When I ran fmtutil-sys --all as instructed, the process terminated with errors. The problem was that, according to texmf.cnf, I had exceeded the memory limit by using main_memory = 50000000:  % Memory. Must be less than 8,000,000 total.  I was wondering why that is the case and whether there is a way to circumvent that limit. If there isn't a limit, what are the maximum values I can set the main_memory, extra_mem_top and extra_mem_bot to? Do the latter two count towards the total memory (I assume they do!)? Is there another variable that is more closely related to the "type of memory" that pgfplots uses so that I can increase that instead?  For your information, I externalize my figures using mode=list and make and I already tried lualatex, but I'm it still complains about running out of memory (even though it uses only around 1Gb of RAM).  I understand that people will argue that it is unnecessary to plot such a large number of data points in such a short space, but I would at least to know why LaTeX imposes such memory limits, especially with memory being so cheap these days.

I am trying to compile a large file which contains a tikz picture with more data points than tex can handle.  Following the questions  and  I set to increase the capacity of tex by changing the file texmf.cnf in my path /usr/local/texlive/2012. I included the line  main_memory = 10000000   and on terminal I run  sudo fmtutil-sys --all   The problem is that this memory is not enough, and numbers bigger than that don't finish the fmtutil run properly. I get the error   fmtutil: Error! Not all formats have been built successfully.   To give a better idea of where the problem is coming from, if I only include in the file texmf.cnf the lines  main_memory.latex = 15000000 main_memory.pdflatex = 15000000   then these are the files which are not properly built:  This is a summary of all `failed' messages: `pdftex -ini  -jobname=latex -progname=latex -translate-file=cp227.tcx *latex.ini' failed `pdftex -ini  -jobname=pdflatex -progname=pdflatex -translate-file=cp227.tcx *pdflatex.ini' failed   How can I increase the size of the memory beyond 10000000? Am I doing anything wrong?  (BTW, I am running texlive 2012 on a mac)


Let $f : \mathbb{R}^n → \mathbb{R}_∞$ be a function and let $C ⊂ dom f$ be a convex set.  $$**Part I**$$ Prove that $f$ is a convex function if and only if $f$ is convex over every line $L_{v,x_0}$ where $L_{v,x_0} := \{x_0 + tv : t \in \mathbb{R}\}$.  i.e. f is convex iff when restricted to any line, it be convex on that certain line.  So essentially to handle this proof I need to show that convexity for $f$ holds when its convex over any arbitrary line, and on the converse it does not hold when $f$ is not convex over that arbitrary line. If $f$ is convex then,  $$\forall x,y \in C, a \in [0,1]$$ it holds that $$f(ax+(1-a)y) \leq af(x) + (1-a)f(y) \space \space\space\space\space\space\space\space\space\space\space\space (1)$$  EDIT: $$**Part II**$$  Let $f : \mathbb{R}^n \to \mathbb{R}_∞$ be a function.   I want to prove that $f$ is convex over the line $L_{v,x_0}$ iff $\psi : \mathbb{R} \to \mathbb{R}_∞$  $\psi(t) := f (x_0 + tv)$, is convex over $I (x_0, v )$.  where $L_{v,x_0}:= \{x_0 + tv : t ∈ \mathbb{R}\}$, and $I(x_0,v):=\{t \in \mathbb{R} : x_0 + tv \in C\}$  Any help is very much appreciated


$A$ is an $m\times n$ matrix and $B$ is an $n\times m$ matrix.  $$ \det(I_m + AB) = \det(I_n + BA) $$ Solution: I found this guys: $$ \det\begin{pmatrix}I&-B\\\\A&I\end{pmatrix} \det\begin{pmatrix}I&B\\\\0&I\end{pmatrix} =\det\begin{pmatrix}I&-B\\\\A&I\end{pmatrix}\begin{pmatrix}I&B\\\\0&I\end{pmatrix} =\det\begin{pmatrix}I&0\\\\A&AB+I\end{pmatrix} =\det(I+AB) $$  and  $$ \det\begin{pmatrix}I&B\\\\0&I\end{pmatrix} \det\begin{pmatrix}I&-B\\\\A&I\end{pmatrix} =\det\begin{pmatrix}I&B\\\\0&I\end{pmatrix} \begin{pmatrix}I&-B\\\\A&I\end{pmatrix} =\det\begin{pmatrix}I+BA&0\\\\A&I\end{pmatrix} =\det(I+BA) $$  Source:

Sylvester's determinant identity states that if $A$ and $B$ are matrices of sizes $m\times n$ and $n\times m$, then   $$ \det(I_m+AB) = \det(I_n+BA)$$   where $I_m$ and $I_n$ denote the $m \times m$ and $n \times n$ identity matrices, respectively.  Could you sketch a proof for me, or point to an accessible reference?


I got a "site may be hacked" warning from Google in one of my Drupal sites and while working to resolve this, I noticed that a hacker gained access to the /includes/theme.inc folder and added codes inside the template_process_html(&$variables) function   I commented out the part that was adding links on my site and kept it as it is. Now after 2 days I checked the site again and saw that another set of codes are inserted in the same function which now looks like this:  // Render page_top and page_bottom into top level variables.   $variables['page_top'] = drupal_render($variables['page']['page_top']);   $variables['page_bottom'] = drupal_render($variables['page']['page_bottom']);   // Place the rendered HTML for the page body into a top level variable.   $variables['page']              = $variables['page']['#children'];   $variables['page_bottom'] .= drupal_get_js('footer');   if($variables['classes_array'][1]=='front')     $variables['page_bottom'] .= '
The beginning of the process you should find some nice bargains is the internet. You could possibly find a websites selling such designer shoes at much reduced prices. You will, therefore, need to observe a quantity of sites and compare prices before finally settling for the offer it is possible to comfortably have. However, you have to remember that you won\'t have the chance to try the shoe you want to purchase. Additionally you need always be wary from the online sale scams.Custom Cheap Jordans is genuine. There are 24 customized versions of Jordans. You can buy, Jordan, does not have any for good quality, very supportive shoes to wear while to the basketball judge. They come in various colors, market, they are generally have a great performance top basketball shoes, 72-10 11s for sale Michael Jordan famous. Women Air Jordan Shoes are designed with women\'s basketball players read more was formed. With superior quality materials and design ...... 100s of links here      $variables['head']    = drupal_get_html_head();   $variables['css']     = drupal_add_css();   $variables['styles']  = drupal_get_css();   $variables['scripts'] = drupal_get_js();   So now it is clear that site has a backdoor, I need to find that backdoor to keep my site clean and remove that warning from Google.

I just updated all my sites using the patch method of resolving the Drupal SA-CORE-2014-005 exploit. I just read reports that just yesterday there is someone from a Russian IP infiltrating drupal sites.     My main concerns are now:   How do I tell if my sites have been comprised? What should I search for in my apache access logs to detect if my site was a victim or not? So far what are these hackers doing to comprised sites?


I've been having this problem for about 4-5 months now. It all started when I joined my boyfriend's hosted server using hamachi. A couple nights later, it started giving me that error. I've recently just factory reset my pc. I tried joining my brother's server (LAN) by typing in the ip or "localhost", but it still gave me the same "failed to connect to the server" message. I've tried:   turning the Firewall on/off uninstalling and installing minecraft restarting the router (even getting a new one) changing port number to 25565 factory resetting my pc   I've tried every solution I could find, but none worked so far. I guess not a lot of people come across this problem. They said theirs were fixed in a couple of weeks, but my problem has been occurring for almost half a year now.  I'm running Java version 8 update 171.

I am getting the following error when I try to connect to a Minecraft server:  This is all servers, not just one. The error says:  io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: no further information: Version 1.12  I've tried:  Restarting Minecraft Restarting Computer Uninstalling and Reinstalling Mincraft Uninstalling and Reinstalling Java Altering Firewall Restarting Internet I've messed with my port, made a second windows account, reset netsh winsock Checked hosts Made a new WINDOWS account  The overlay in the bottom right is Geforce's Overlay for game capturing. I don't have any mods installed. A Mojang support ticket wouldn't help. Im desperate.


In a  the Doctor has, in his fourth and eleventh incarnations landed on the Enterprise. Regardless of whether Kirk or Picard he has entered the trek universe but in "The Impossible Astronaut" an elderly woman asks a member of The Silence if his costume is from the Star Trek show.  My question is, can the Star Trek universe and 'Whoniverse' coincide with each other? Also if they can be linked together could the aliens from Star Trek appear on Doctor Who?  I feel as though mixing them would give a larger audience to both shows. Would there be as many legal complications in using the aliens like romulins, volcan, borgs etc... in Doctor who?

IDW Publishing are bringing out a , Assimilation2, set in ST:TNG (presumably the TNG in the timeline prior to the events of the 2009 movie) featuring the 11th Doctor.  Is the canon of these two universes at all compatible?  Both feature a lot of time travel, so we've seen the development of humanity through many centuries in the future.  Are there direct contradictions that make it impossible for these two universes to merge, without some sort of trick like having the Doctor come from an alternate universe?  Or, given the vast spread of time, is it possible that the events of the Star Trek stories have taken place between Doctor Who stories?


I want to activate Windows with a product key by doing a clean install.Is it possible to get rid of digital entitlement on a system

I'm currently running Win10 Pro and I'm looking to upgrade to Win10 Enterprise (to get rid of Windows bloatware and telemetry etc). Is it possible to install Enterprise while keeping my installed programs? I'm not worried about my files as I have them on a separate drive. I'm just worried about registry stuff because I really want to avoid the hassle of reinstalling and reactivating all my software. I've recently discovered Win10 Education but a) I'm not sure if I can keep it forever, and b) it doesn't include Cortana and I'm not sure if the taskbar search bar is part of Cortana because if it is I don't want to lose it because I use it a lot.  Recap: I'm on Win10 Pro, I want Win10 Enterprise but without losing my programs. Win10 Education is an option but I'm not sure if a) there is a time limit and b) if it removes the search bar at the bottom.  Can anyone shed any light on this?


Is it possible for a dual national who happens to be a citizen of two countries to travel between two countries who can accept only national IDs upon entry from their own nationals, and hence not require stamps to their passports (either because they're not stamped by their own authorities either because they're not necessary)?  Let's say I'm a citizen of Belgium and the UAE, and both countries require only national ID(s) from their respective citizens to enter. Can I simply switch between national IDs, in a proper manner of course?

I am a citizen of two different countries, and have two passports.  How should I use my passports when traveling?


Let f : [a, b] → R be continuous. Assume that there exist constants α and β such that ∀c ∈ [a, b], we have α$\int_a^c$f(x) dx + β$\int_c^b$f(x) dx = 0. Show that f = 0. I guess there is a mistake in the question since if α and β = 0 , then the condition is satisfied but the fuction need not be zero function. If α $\ne$ 0 and β $\ne$0, I think f = 0. But I can't prove it. Please give a hint

If $f$ is continous in $[a,b] \subset \mathbb{R}$ and exist real numbers $\alpha \not= \beta$ such that $$\alpha\int_{a}^{c} f(x) dx + \beta\int_{c}^{b} f(x) dx  =0$$ for all $c \in [a,b]$ show that $f (x)=0$ for all $x \in [a,b].$


A commutative ring $R$. The set $\Sigma$ consists of all ideals in which every element is a zero-divisor. Clearly $\Sigma$ has a maximal element $M$. I want to prove that $M$ is a prime ideal of $R$. (Atiyah & MacDonald Ex.1.14)  Here is my idea: suppose that $M$ is not prime. Choose $a, b\in R-M$ such that $ab=m\in M$, and argue that $(M\cup {a})$ is an ideal consisting of zero-divisors. But how to prove this? I have no idea.

This is in follow-up to .     Let $R$ be a commutative ring with identity and consider the set $Z \subset R$ of zero divisors. If the ideal $I\subset Z$ is maximal with respect to the constraint, need it be prime?    Since Zorn's Lemma applies equally well to proving that either minimal prime ideals exist or that maximal ideals contained in $Z$ exist, this would provide an alternative proof of that question if true.  A naive approach to proving this is to assume $ab \in I$ with $a, b \notin I$. Since $ab \in I$, it follows that $ab$ is a zero divisor, so $abx = 0$ for some $x \neq 0$, and therefore either $a$ is a zero divisor annihilated by $bx \neq 0$ or $b$ is a zero divisor annihilated by $x$. In either case, the obvious thing to consider would be $aR+I$ or $bR+I$, but there's no obvious reason why either of these ideals should consist of zero divisors.  According to rschwieb, the answer is yes for reduced Noetherian rings.


I have two networks at my home -- a LAN where I'd like to share my files, and a phone that provides my only Internet via a wi-fi hotspot feature. Hoping to access both at once, I outfitted my Windows 8 laptop with a second network adapter.  Unfortunately, as soon as I try connecting to the LAN, every request for a webpage bounces off the LAN router, and fails. The order I connect to these two wi-fi networks doesn't seem to change this problem.  What do I do to remedy the situation? Is there some way to change which network is used for Internet connectivity? I can configure my router, but probably not my wi-fi hotspot.

I have been tring this for a while now, without success. I have read online this can be done, either by changing the default gateway (DG) or messing with the DG's metric  The short story is: I need to connect to my company's ERP system (port 80 for some web services and port 22 for sftp and bash) with using my notebook computer's LAN card - but I can't connect to the Internet on this network. So I have my mobile phone's 3g hotspot when I need to go online. But I want to use both at the same time without so much as opening another web browser process.  At the moment, I am using the ERP system regularly - and whenever I need to go online to check a mail or research something related to work, I need to unplug the network cable so the wifi can kick in... which is starting to become annoying especially if I am connected to the ERP system using FTP (Filezilla) or Shell (putty)  Can someone help me with the configurations?  Below are some of the details I can provide:  Wired network - office LAN - for connection to the ERP system: DHCP -    Yes IPv4      10.64.200.245 Subnet    255.255.240.0 DG        10.64.193.254 DHCP Serv 10.64.17.191 DNS       10.68.72.200           10.68.20.200 WINS      10.68.77.200           10.64.20.200   Below are the details for my WiFi internet connection - over my mobile hotspot  DHCP      Yes IPv4      192.168.43.39 <- I'm guessing this changes every time I restart the wifi subnet    255.255.255.0 DG        192.168.43.1 DHCP      192.168.43.1 DNS       192.168.43.1   Finally, here is the tracert results (btw, I'm on Windows 7, 64bit and the remote system should be on Linux) - the target ERP ip address is 10.76.142.39  Tracing route to 10.76.142.39 over a maximum of ...    1    <1 ms    <1 ms    <1 ms  10.64.193.253   2    <1 ms    <1 ms    <1 ms  10.64.4.13   3    <1 ms    <1 ms    <1 ms  10.76.23.124   4     1 ms    <1 ms    <1 ms  10.76.23.93   5     1 ms    <1 ms    <1 ms  2xx-xx-xx-9.adsl...   6     1 ms     1 ms     1 ms  2xx-xx-xx-9.adsl...   7     1 ms     1 ms     1 ms  2xx-xx-xx-10.adsl..   8     2 ms     1 ms     2 ms  10.76.135.125   9     1 ms     1 ms     1 ms  10.76.142.39   sorry, I had to mask out some details above... wasn't sure if they would have any confidentiality issues.  Any help is much appreciated.


Suppose I have $A_1 \to B$ and $A_2 \to B$ in some category where fiber products exist. I am stuck on trying to prove that it is unique up to unique isomorphism. Suppose I have $C$ with $\pi_i: C \to A_i$ and $D$ with $p_i: D \to A_i$ both satisfying the universal property as a fiber product of $A_1 \to B$ and $A_2 \to B$. I want to show $C$ and $D$ are isomorphic. Let  $\phi: D \to C$ and $\psi: C \to D$ obtained by the universal property. What I can get by drawing commutative diagrams is $$ p_i \circ \psi \circ \phi = p_i \circ Id_D.   $$ How can I prove $\psi \circ \phi = Id_D$ from here? Thank you.

Browsing some , it is claimed that two universal objects are isomorphic because they admit the identity morphism on themselves. But from two identity morphisms, how would you get an isomorphism between the two?


I intend to have a Javascript/HTML5 game with a global leaderboard. I have devised a very simple system for submitting highscores as follow:     When the game finishes, the game client makes a POST request to server hosting the leaderboard that contains the name of the player and their score. Then, the server inserts the submission into its database.   However, this system can easily be cheated by an individual with an html form submitting POST requests with whatever score they want to my server.  I already know that a foolproof anti-cheat system is impossible because of how easy it is to modify Javascript and HTML on the client. I also know that I should never trust the client. However, implementing everything on the server side will be impractical for me since my server will not have the resources necessary to perform all the calculations for all the players.   So instead, I simply wish to make it as hard as possible for the average individual to cheat (and recognizing that it will always be possible to cheat), while making it as easy as possible for me to identify when a score that was submitted might possibly be fake.   What are strategies I can use to accomplish such? Please include examples whenever possible. For example, I have heard someone suggest using "pre-shared keys". However, I am not a cryptography expert and I have no idea how to go about implementing that.

I'm planning on venturing on making a single player action rpg in js/html5, and I'd like to prevent cheating. I don't need 100% protection, since it's not going to be a multiplayer game, but I want some level of protection.   So what strategies you suggest beyond minify and obfuscation?  I wouldn't bother to make some server side simple checking, but I don't want to go the Diablo 3 path keeping all my game state changes on the server side.  Since it's going to be a rpg of sorts I came up with the idea of making a stats inspector that checks abrupt changes in their values, but I'm not sure how it consistent and trusty it can be.  What about variables and functions escopes? Working on smaller escopes whenever possible is safer, but it's worth the effort?  Is there anyway for the javascript to self inspect it's text, like in a checksum?   There are browser specific solutions? I wouldn't bother to restrain it for Chrome only in the early builds.


I have a CSV with 500 ship routes.  Every row is a different trip and the columns have the values of ship_name, lat_1, lng_1, lat_2, lng_2,lat_3, lng_3... lat_20, lng_20  How can I insert this information in QGIS and create polylines between this coordinates?

I have a CSV file where one line looks like this:  Duration, user, lat-start, long-start, lat-end, long-end 298, Casual,38.9101,-77.0444,38.91554,-77.03818   Each row in the CSV has two points and I need to draw a line between those two points for each row.   How can I do this using QGIS 1.8.0?   I have tried using the delimited text file plug-in, but it just draws points and has no line option from what I can see.


I was uninstalling Ubuntu when I restarted my computer and it booted to grub terminal type. The problem is my keyboard is on (the lights work), but the keys are not working. I tried entering BIOS, no luck. I don’t know what to do. I have tried everything. I can't type anything and have tried all my USB ports.  If I unplug my mouse it shows the options for the BIOS and stuff, but when I press the key it does nothing.

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


I am a computer teacher. I am introducing my students to Linux, and I wish to create a multi boot live-DVD (single layer, 4.5GB)  with all the Ubuntu flavors (Kubuntu, Lubuntu, Xubuntu and Ubuntu 14.04) to use it in class. I have tried the following Windows utilities (because I am used to Windows, but I also have installed Ubuntu 12.04 LTS on my computer): - X-boot: the ISO image is too big to fit in a single DVD (it duplicates the ISOs). - SARDU: only support certain flavors of Ubuntu (Ubuntu y Kubuntu) - Magic ISO: created the ISO image successfuly, but it failed to recognize the blank DVD in the DVD unit. Tried to burn the ISO with Nero, but the DVD does not boot, an error message appears.  I got tired to search over the internet, so I hope someone could help me  Regards  Jorge Arce Ortiz

I always find it a waste putting a 790MB Ubuntu iso on a 4GB DVD, and I was wondering how to put multiple operating systems on one DVD with a grub menu. I know it is possible, but I just don't know how!


On stackoverflow.com I can edit a post and it goes into a queue for approval. The Android app let's me do the edit and then says 'this account is not allowed to edit'. Either it should allow me to edit or it should not. I like the look and feel of the app.

I edited a question, on Stack overflow and when submitting preview, got red bar telling me my account isn't allowed to make suggested edits.  On the Sandbox android question it works fine, but that is editing an answer to my question.   The message I receive is:     Account is not allowed to suggest edits   Are the rules for suggested edits different for Android app?


I tried to put some thai sings into a utf8 (utf8_general_ci) mysql database. The data is from the facebook api. In the JSON it looks like \u0e41\u0e15\u0e07\u0e08\u0e49 (original: แตแจ้) and in the database i got some ???? (question marks).  What is the best solution to save this characters into a database?  This is my database connection with mysqli:  $DB = new mysqli('localhost', 'XXX', 'XXXXXX', 'XXXX'); $DB->query("SET CHARACTER SET 'UTF8'"); $DB->set_charset("UTF8");

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


Which is correct? Paul's and Freda's Anniversary or Paul and Freda's Anniversary?

Which option is grammatical?        There will be readings from Nikki Giovanni’s and Alice Walker’s writings.   There will be readings from Nikki Giovanni and Alice Walker's writings.      Saying it out loud the latter sounds right, but looking at it the former looks better.


Is there a way to use both a firewall and a vpn app on android. I have tried allowing the vpn through the firewall but one invaraibly goes off when I start the other. Is there some way around this -- to establish two tunnels at the same time.

I'm using the only open source firewall for Android:  and would like to use a VPN in addition. Is this possible? If so: how?  Both types of apps typically use virtual VPN tunnels. NetGuard has network settings too.


I'm new to linux and ran into this error, couldn't figure out how to fix it. Help much appreciated! "sudo apt-add-repository 'deb  bionic main' E: Malformed entry 1 in list file /etc/apt/sources.list.d/wine-obs.list (Suite) E: The list of sources could not be read."

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


So i have this value that i simply want to "cout" it double f = -922337203.6854775808; std::cout.precision(19); //cout.setf( std::ios::fixed, std:: ios::floatfield ); cout << f<< endl;  output : -922337203.6854776144 value changes here. Any information can help.

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


does anybody know how to enable fingerprint login in a LUBUNTU LXQT 0.14.1? I have a Lenovo X230 Thank you

I have a  with a fingerprint reader:    How to make Ubuntu recognise it and use it for login?  I already tried:  sudo add-apt-repository ppa:fingerprint/fingerprint-gui sudo apt-get update   ... but this GUI did not recognizes my device. Does anyone knows any other option?


I intended to zip a directory, so I used:  gzip -r myfolder   When I checked the output, it has been zipped all the files within the directory and its subdirectories. It wasn't what I explected  How can I unzip these so many zipped files to their original state?

I am learning Linux and I was trying the gzip command. I tried it on a folder which has a hierarchy like  Personal/Folder1/file1.amr Personal/Folder2/file2.amr Personal/Folder3/file3.amr Personal/Folder4/file4.amr   I ran     "gzip -r Personal" and now its like  Personal/Folder1/file1.amr.gz Personal/Folder2/file2.amr.gz Personal/Folder3/file3.amr.gz Personal/Folder4/file4.amr.gz   How do I go back?


Reading the Hunger Games books and watching the movies, I have noticed that everyone in Panem's districts seems to live in the same general area. Everyone in District 12 knows everyone; there is no mention of people having to travel to a central city in the district in order for the Reaping to be conducted.   This seems strange, considering that the districts are all rather large. Yes, the war nearly a century ago decimated the population, and yes, famine has been a problem. But is it realistic to expect everyone living in a large district to live in the same central area?   Could the population in the districts other than 12 be more spread out, requiring Reaping procedures to be different? Or are all districts like 12, with the entire population apparently living in only one small central area?  Would Reaping procedures have to be more complicated than the books suggest?

In , the nation of Panem (implied to be North America after some sort of post apocalyptic scenario) is divided into 13 districts and the Capitol. District 12 is hinted to be in the Appalachia Mountains, and the Capitol is hinted to be in the Rocky Mountains. District 13, which was destroyed, is described as "east of District 12", which made me think it's where Washington D.C. is today.  The other districts, however, were mostly ignored, and almost no detail was provided as to their locations in the books. Has there been any supplemental information that reveals where the districts are?


I am viewing it with pdflatex.  I could not understand the other question's solution   \documentclass[12pt]{proc}  \usepackage[margin=1in]{geometry} \usepackage{graphicx}  \title{Bus Rapid Transit} \author{Mohamed Mirza} \date{May 9, 2018}   \begin{document} \maketitle  \section{Introduction}  A common phenomenon that has repeatedly been experienced by humanity is  urbanization. Urbanization, which happens to share the same suffix as  modernization and industrialization, represents the expanding number of  individuals that populate urban areas, e.g. cities and suburbs. Currently,  over 54\% of the entire human population lives within urban areas and that  number is only expected to increase in the coming years. Following this  population shift from rural to urban areas, cities within the Twenty-First  Century face a plethora of problems at unprecedented levels.   A current problem faced by densely populated cities revolves around traffic  congestion. Traffic congestion is dynamic since it negatively affects  several components of society. Public transportation systems suffer  directly en masse as a result of traffic congestion.   Transportation systems are central to fueling a city's economic  productivity and can influence positive socio-economic environment changes  that lead to community development. Hence, there has been a growing  interest from federal governments and academic institutions to study and  examine how different forms of transportation systems react to traffic  congestion in an attempt to better design and replace aging infrastructure  to serve stakeholders. In order to examine how a Bus Rapid Transit system,  also represented by the acronym \textbf{\emph{BRT}}, can benefit cities, it  is important to first understand what a transportation system is and its  effect on economic, social, and physical systems.   \end{document}

Could anyone tell me why the date is not being shown in the title of my document. The document class is proc. If I remove \date{\today} my title moves down a return, but no date is displayed when I leave it in.   \title{Title} \author{Me\\         Email\\} \date{\today} \maketitle


I have appeal for refusal of Schengen visa (Spain), but I decided to apply for fresh visa from other Schengen State (Czech Republic). I want to know, does my appeal to Spain affect my visa in Czech Republic? How to cancel appeal of visa refusal?

My visa got denied by the Greek embassy in Abu Dhabi for the reason below: the information submitted regarding the justification for the purpose and conditions of the intended stay was not reliable.  Does it make sense to appeal for this?  I have no idea why they denied my application while my friend got hers. We applied together and submitted the same documents, booked hotels and tickets. My purpose is a tour for 6 days.  Here are the documents I submitted:   Schengen visa application form (Greece) copy of my passport recently renewed valid from 16/05/2015 to 15/15/2017 copy of my UAE visa valid 2017/05/13 3.5 x4cm photo in white background RSA travel insurance with a coverage of Euro 30,000 from 02/10/2015 to 10/10/2015 6months NBD bank account statement with a nice balance (original with bank stamp) No-objection letter from my employee stating my position, salary, date of my recruitment. Booked hotel & ticket fares with itinerary details


Let $\tau$ be a transposition (2-cycle) in $S_n$. Prove that for all permutations $\sigma$ in $S_n$, that $\sigma\tau\sigma^{-1}$ is a transposition.  It is clear to me that the order is 2, but it is not necessarily clear that $\tau$ is a transposition.

I have heard that two permutations are conjugate if they have the same cyclic structure. Is there an intuitive way to understand why this is?


I set up external flash drive to run ubuntu. How do I get it to work and not load windows XP?

I would like to see a full how-to guide on how to install Ubuntu.


float num1 = 1;  if (num1 == 1) {      printf("Yes, it is equal!!\n"); } else {      printf("No, it is not equal\n"); }   output -->  Yes, it is equal!  whereas  float num1 = 1.2;  if (num1 == 1.2) {     printf("Yes, it is equal!!\n"); } else {     printf("No, it is not equal\n"); }   output -->  No, it is not equal  but why?  Please explain in detail.


Where are the 'I/O Read Bytes' & 'I/O Write Bytes' columns in task manager in Windows 8? In Windows 7 there was a list of columns where one can chose the columns to display. I can't find the equivalent in Windows 8?

Up until Windows 7, the  of the  would allow you to add the  (see for instance ):     to show it, choose theView menu, click Select Columns and check the CPU Time.   As of the ,    the Select Select Columns menu item is gone the App History tab has a CPU Time column the App History tab only shows Metro style apps (not all processes)   How (apart from using non-TaskManager tools like ) can I get the CPU Time column back in the Processes tab?


I have an orthomosaic GeoTIFF and it has 4 bands. I want to convert it to a PNG/JPEG image to show it on Cesium. I've tried gdal_translate like this : gdal_translate -a_nodata 0 -of PNG 1.tif 1.png -scale -colorinterp_1 red  -colorinterp_2 green -colorinterp_3 blue and it's not working. I'm completely new to QGIS. Can you please guide me what options I should use to get data? I already have 2D generated picture using photoshop and I think it's not losing any data. I don't want to keep projection or elevation data. I just want a normal image.  Point: it's not possible for JPG because I'm getting this error : libjpeg: Maximum supported image dimension is 65500 pixels  This is gdalinfo result :  Files: /Users/tfiroozian/Downloads/2_111318_SKYG_Nautilus_1_3mi_transparent_mosaic_group1.tif Size is 41705, 77008 Coordinate System is:  PROJCS["NAD_1983_StatePlane_Texas_Central_FIPS_4203_Feet",     GEOGCS["NAD83",         DATUM["North_American_Datum_1983",             SPHEROID["GRS 1980",6378137,298.2572221010042,                 AUTHORITY["EPSG","7019"]],             AUTHORITY["EPSG","6269"]],         PRIMEM["Greenwich",0],         UNIT["degree",0.0174532925199433],         AUTHORITY["EPSG","4269"]],     PROJECTION["Lambert_Conformal_Conic_2SP"],     PARAMETER["standard_parallel_1",30.11666666666667],     PARAMETER["standard_parallel_2",31.88333333333333],     PARAMETER["latitude_of_origin",29.66666666666667],     PARAMETER["central_meridian",-100.3333333333333],     PARAMETER["false_easting",2296583.333333333],     PARAMETER["false_northing",9842500],     UNIT["US survey foot",0.3048006096012192,         AUTHORITY["EPSG","9003"]]] Origin = (1285949.954140000045300,10626980.503550000488758) Pixel Size = (0.081470000000000,-0.081470000000000) Metadata:   AREA_OR_POINT=Area   TIFFTAG_SOFTWARE=pix4dmapper Image Structure Metadata:   COMPRESSION=LZW   INTERLEAVE=PIXEL Corner Coordinates: Upper Left  ( 1285949.954,10626980.504) (103d35'10.24"W, 31d46'58.51"N) Lower Left  ( 1285949.954,10620706.662) (103d35' 8.11"W, 31d45'56.45"N) Upper Right ( 1289347.660,10626980.504) (103d34'30.89"W, 31d46'59.49"N) Lower Right ( 1289347.660,10620706.662) (103d34'28.77"W, 31d45'57.43"N) Center      ( 1287648.807,10623843.583) (103d34'49.50"W, 31d46'27.97"N) Band 1 Block=41705x1 Type=Byte, ColorInterp=Red   NoData Value=-10000   Mask Flags: PER_DATASET ALPHA  Band 2 Block=41705x1 Type=Byte, ColorInterp=Green   NoData Value=-10000   Mask Flags: PER_DATASET ALPHA  Band 3 Block=41705x1 Type=Byte, ColorInterp=Blue   NoData Value=-10000    Mask Flags: PER_DATASET ALPHA Band 4 Block=41705x1 Type=Byte, ColorInterp=Alpha   NoData Value=-10000

I have a number of aerial photos containing both RGB and a near-infrared band. The images are in TIF-format, however I need to convert them to PNG without losing any of the bands. I have tried converting/exporting data in ArcMap, however this fails, unless I choose to "use renderer" in the "Export Data" dialogue, resulting in only 3 bands being saved.  I have also tried the GDAL-translate alghorhitm in QGIS, however this didn't seem to work either.  Do I have any other options?


I have a few commands that I need to run to install some packages, including going into virtual environment to activate and it feels tedious to copy paste them one by one. So is there a way that I can wrap them up in a script file, and just run the script file with a command like running a powershell script? sudo apt update sudo apt-get install python3-dev sudo apt-get install python3-venv python3 -m venv env      cd env . bin/activate sudo apt install python-pip pip install --upgrade pip sudo apt-get install libgeos-dev sudo apt-get install libpq-dev etc```

In Windows I can write a file containing commands for cmd (usually .cmd or .bat files).  When I click on those files it will open cmd.exe and run them commands the file contains.  How would I do this in Ubuntu?         I'm sure this is a duplicate, but I can't find my answer. Its similar to these questions, but they don't answer the question:


I am running 18.04LTS and am trying to get my system to download the 20.04 release.  Running update-manager with no arguments is failing.  It starts downloading the repository information, gets 90% done, then aborts with "Failed to download repository information.  Check your internet connectiion."  I am able to ping, traceroute and http to www.ubuntu.com and archive.ubuntu.com with no problems.  My internet connection is just fine for other destinations.  Now "apt update" is not working.  sudo apt update [sudo] password for jms:  Hit:1 http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease Hit:2 http://archive.ubuntu.com/ubuntu bionic InRelease Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]       Ign:4 http://ppa.launchpad.net/videolan/stable-daily/ubuntu bionic InRelease    Err:5 http://ppa.launchpad.net/videolan/stable-daily/ubuntu bionic Release        404  Not Found [IP: 2001:67c:1560:8008::15 80] Get:6 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB] Get:7 http://archive.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB] Exception ignored in: <_io.TextIOWrapper name='<stdout>' mode='w' encoding='UTF-8'> BrokenPipeError: [Errno 32] Broken pipe Reading package lists... Done E: The repository 'http://ppa.launchpad.net/videolan/stable-daily/ubuntu bionic Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. W: Skipping acquire of configured file 'allow-insecure=yes/binary-i386/Packages' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/binary-amd64/Packages' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/i18n/Translation-en' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/i18n/Translation-en_US' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/dep11/Components-amd64.yml' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/dep11/icons-48x48.tar' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/dep11/icons-64x64.tar' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?) W: Skipping acquire of configured file 'allow-insecure=yes/cnf/Commands-amd64' as repository 'http://ppa.launchpad.net/mc3man/bionic-media/ubuntu bionic InRelease' doesn't have the component 'allow-insecure=yes' (component misspelt in sources.list?)

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


Is there a way that we can solve a system of congruences,  $x \equiv m \, (modp)$   $y \equiv n \, (modq)$  while satisfying the condition $x+y=N$, when $m,n,p,q$ and $N$ are known?  Here $p,q$ are primes, $N=p^2 q$ and   case 1: $m=p, n=q$  case 2:$m=n=0$  Thanks a lot in advance.

We want to find the solution $x$ to the congruence system  $$\begin{align} x &\equiv r_1 \!\!\!\pmod{\!m_1}\\ x &\equiv r_2 \!\!\!\pmod{\!m_2}\end{align},\ \ {\rm where}\ \  \gcd(m_1, m_2) = 1$$  These can be rewritten as  $$\begin{align} x &= r_1 + m_1 j\\ x &= r_2 - m_2k\end{align}$$  for unknown integers $j, k$. So we set those two equations as equal and rearrange them to  $$m_1j + m_2k = r_2 - r_1$$  Now assume we perform $\text{egcd}(m_1, m_2)$, which gives us the solution to  $$m_1u + m_2v = \gcd(m_1, m_2)$$  Let the integer $\,h\,$ make $\,h \gcd(m_1, m_2) = r_2 - r_1$.  Then $\qquad hm_1u + hm_2v = h\gcd(m_1, m_2) =  r_2 - r_1 = m_1j + m_2k$  At this point I am lost because I don't think we can just assume  $hm_1u = m_1j$ and extract $j = hu$.   How do I get the values of $j$ or $k$ so I can get the value of $x$?


I'm attempting to access a Child Business Unit using an Installed Package created in the Parent Business Unit. I am POSTing this payload {   grant_type: 'client_credentials',   client_id: {{ Parent Business Unit client_id }},   client_secret: {{ Parent Business Unit client_secret }},   account_id: {{ Child Business Unit MID }} }  to https://<yourSubdomain>.auth.marketingcloudapis.com/v2/token The error message I'm getting back from the API is {   "error": "invalid_client",   "error_description": "Client authentication failed. Make sure that the client ID and client secret are valid and that the package is installed and enabled.",   "error_uri": "https://developer.salesforce.com/docs" }  I know that the credentials are working because I can successfully get an access token for the Parent BU. I reviewed the post here  and the accepted answer doesn't solve the issue. Is there something I'm missing in the docs about how to access the Child BU?

We have our main BU (business unit) at the top of the tree, and one of the other BUs is TEST. In TEST we have created an Installed Package and in that installed package we have added a Server-to-Server API Integration. In the Access tab of that API Integration we've disabled the integration for the Parent BU, and have enabled it for the TEST BU.  When we make Rest API calls to the endpoint created in that API Integration we always get data from the "Main" BU, and not from the TEST BU.  If I create a contact that is available in both the Parent and TEST BU, but if I try to trigger an email based on a Triggered Send definition only the definitions created in the Parent BU are available and not the definitions from the TEST BU.  How can I access the data in the TEST BU from the Rest API? And why aren't the permissions preventing me from taking actions on the Parent BU?


There have been several times I have been helping a user with a question and things aren't quite working out perfectly, and the comments keep getting longer and longer and longer. We've all been there, the comment system isn't made for long discussions, and at some point we just want to throw up our hands and give up.  I've tried creating a chat room to discuss the issue in a better environment, but if they have less than 20 reputation that isn't possible. If you are room owner of that chat room (like you probably are if you created it) and have 1k rep you can make a room read-only, but you can't give a user explicit write access to a room, even though you have access to the controls.     TL;DR  Can we please allow users with 1k (or some amount) of reputation the ability to give write access to users with less than 20 reputation in chat? .    This question  is related, but isn't really the same request.

I'm aware of the preference for 'general answers to general questions' attitude on SO, and wholeheartedly agree that questions that are focused on specific, one-time issues are not as valuable to the site.  However, where an issue is potentially useful but getting to the heart of it is taking some doing, the obvious option is to migrate the discussion to chat.  Once the user has a better understanding of their issue, the question can be edited to a useful form and answered succinctly for future readers.  The issue, as noted in other questions here, is that these situations most often occur with a sub 20 rep user, and so with the chat feature denied a long discussion in the comments becomes likely.  I totally understand the sentiments expressed here: , and I don't feel that a chat session should be used to completely solve a users problem, but it would be nice if the chat could be made available while a user's issue is being made clear.  And so...  The Actual Proposal  Would it be possible to enable the invite to chat feature for sub 20 rep users, based on an invite from a higher rep user who can be trusted to use the chat conversation in the correct manner and take the results back to the originating question?    The sub 20 rep user could be locked to that single chat instance, and still unable to participate in the main boards.  The inviting user should have a much higher rep, somewhere in the thousands, and so would hopefully use the feature responsibly in a way that was aimed at providing a worthwhile question and answer as the result.


I sometimes install .deb files that have a "Provides" field. From what I understand, if e.g. a package called "expack" is listed here then if another .deb file depends on expack it will not need to install it (if I do apt-get). But if I do apt-cache show expack then it will not show that it's installed. So how do I check that the 'expack' dependency is installed (without using a specific package that depends on 'expack', just using only the argument 'expack') ?

Possible Duplicate:          I want a shell script method to test/report if a package is installed. I don't need details, only a yes/no.  I've come up with this method. Is there a more direct way?  is_installed=0 test_installed=( `apt-cache policy domy-ce | grep Installed: ` ) [ ! "${test_installed[1]}" == "(none)" ] && is_installed=1


I want to know what unique IDs exists in Windows. I can think of the Volume Serial Number:  VOL C:   But this is a 32-bit number and so it is not too hard to have collisions.  There is also the HDD serial number:  wmic DISKDRIVE GET SerialNumber   Are there any other unique IDs?  Note: I know that I can generate my own GUID but this is not what I want.

I need to write a function that generates an id that is unique for a given machine running a Windows OS.  Currently, I'm using WMI to query various hardware parameters and concatenate them together and hash them to derive the unique id. My question is, what are the suggested parameters I should use?  Currently, I'm using a combination of bios\cpu\disk data to generate the unique id. And am using the first result if multiple results are there for each metric.  However, I ran into an issue where a machine that dual boots into 2 different Windows OS generates different site codes on each OS, which should ideally not happen.  For reference, these are the metrics I'm currently using:  Win32_Processor:UniqueID,ProcessorID,Name,Manufacturer,MaxClockSpeed Win32_BIOS:Manufacturer Win32_BIOS:SMBIOSBIOSVersion,IdentificationCode,SerialNumber,ReleaseDate,Version Win32_DiskDrive:Model, Manufacturer, Signature, TotalHeads Win32_BaseBoard:Model, Manufacturer, Name, SerialNumber Win32_VideoController:DriverVersion, Name


I know the CMYK code.(100, 64, 0, 75) I want to know the Ral color for this code. I need help from someone I know.

A client needs to produce a large logo for their front office and the production company requires us to convert the CMYK 40,48,77,17 to RAL or Pantone. I have never been faced with such a request and not sure how to approach this correctly? The logo is black text + an icon in this single CMYK code (flat color). thanks


Prove that $$\sum_{n=1}^{\infty}\frac{1}{n^2}=\frac{\pi^2}{6}$$  I have actually got the HINT for this Proof from a very nice book:  The HINT i started with is:  $$\frac{1}{\sin^2 x}=\frac{1}{4\sin^2\left(\frac{x}{2}\right)\cos^2\left(\frac{x}{2}\right)}=\frac{1}{4}\left(\frac{1}{\sin^2\left(\frac{x}{2}\right)}+\frac{1}{\sin^2\left(\frac{x+\pi}{2}\right)}\right) \tag{1}$$  Now we have:  $$1=\frac{1}{\sin^2\left(\frac{\pi}{2}\right)}=\frac{1}{4}\left(\frac{1}{\sin^2\left(\frac{\pi}{4}\right)}+\frac{1}{\sin^2\left(\frac{3\pi}{4}\right)}\right)$$  Applying $(1)$ Repeatedly we get  $$1=\frac{1}{16}\left (\frac{1}{\sin^2\left(\frac{\pi}{8}\right)}+\frac{1}{\sin^2\left(\frac{3\pi}{8}\right)}+\frac{1}{\sin^2\left(\frac{5\pi}{8}\right)}+\frac{1}{\sin^2\left(\frac{7\pi}{8}\right)}\right)$$  So Generalizing we get:  $$1=\frac{1}{4^n}\sum_{k=0}^{2^n-1} \frac{1}{\sin^2\left(\frac{(2k+1)\pi}{2^{n+1}}\right)}$$  EDIT:  Ok let me explain the next step the author of the book has followed: $$1=\frac{1}{4^n}\sum_{k=0}^{2^n-1} \frac{1}{\sin^2\left(\frac{(2k+1)\pi}{2^{n+1}}\right)}=\frac{2}{4^n}\sum_{k=0}^{2^{n-1}-1} \frac{1}{\sin^2\left(\frac{(2k+1)\pi}{2^{n+1}}\right)}$$  My doubt is how a factor of $2$ came outside and why the upper limit has changed?

As I have heard people did not trust Euler when he first discovered the formula (solution of the ) $$\zeta(2)=\sum_{k=1}^\infty \frac{1}{k^2}=\frac{\pi^2}{6}.$$ However, Euler was Euler and he gave other proofs.   I believe many of you know some nice proofs of this, can you please share it with us?


Using the following bit of code in an otherwise black text:  \color[HTML]{636060}27.~Mai/1.~Juni: Gegenregierung in Kanton unter Sun Ke (☞~S.~\pageref{bio:SunKe}). Diese wird im Dez. von Nanking kooptiert.   produces the required grey paragraph, except that the referenced page number is still displayed in black.   The relevant line in the preamble is:  \usepackage[colorlinks,filecolor=black,linkcolor=black,citecolor=black,urlcolor=black,breaklinks,pdfa]{hyperref}   changing that to e.g.: \usepackage[colorlinks,filecolor=black, %linkcolor=black, citecolor=black,urlcolor=black,breaklinks,pdfa]{hyperref}  of course defaults ALL references to red. As far as the hyperref documentation is concerned “23  Localized nullifying of package” appears to be relevant. I can't make sense of that code.  Summing up the question: Is there a (simple) way of definig linkcolor (here [HTML]{636060}) for a single/few instances only?

I've got a document where I'd like two colours of links - cyan for links in headers that since it's brighter, and navy blue for links in the main body which is more subtle/less distracting. I already tried using the xcolor package and changing the text colour with textcolor, like \textcolor{cyan}{\href{url.com}{link name}}, but it doesn't override whatever link or url colour I have defined in hypersetup.   So this is what I've done:   I've defined the colour navy:   \definecolor{navy}{HTML}{2F729C}    And also imported the hyperref package and defined commands to set the global link/url colours to cyan / navy.   \usepackage{hyperref}                         \hypersetup{colorlinks=true,linkcolor=navy,urlcolor=navy}                        \newcommand{\navylinks}{\hypersetup{linkcolor=navy,urlcolor=navy}}               \newcommand{\bluelinks}{\hypersetup{linkcolor=cyan,urlcolor=cyan}}     Then I've defined another command specifically for the header links, where I turn on cyan links globally, include the header text and link, and then turn on navy links again:   \newcommand{\headerlink}[1]{\bluelinks\href{#2}{#1}\navylinks}   My issue with this is that I feel like there could be a better way to do it than to set the global link colour every time I use a link macro; is there a way to define the link colour just for one link, like one would do with \textcolor{...}, that would be able to override hypersetup?


$A$ is positive-defined matrix, and we define $f: \mathbb{R}^n \to \mathbb{R} $ by: $$f(x) = <Ax, x> + 2<b,x> +c$$ Where $b \in \mathbb{R}^n$ and $c \in \mathbb{R}$. Find the absolute minimum of the function. I was able to get the derivative, and I got $\nabla f(x) = 2Ax+2bx$ and therefore the derivative is $0$ for $x_0$ such that $Ax_0=-b$. For such $x_0$, we have $f(x_0)= <-b,x_0>+2<b,x_0>+c = <b,x_0>+c$   Now how do I prove this is the minimal value? I need to prove that $f(x) \geq <b,x_0>+c$  How do I do that?

Let $f(x) = \frac{1}{2}x^tQx-b^tx, Q\in\mathbb{R}^{n\times n}$   symmetric definite positive and $b\in\mathbb{R}^n$. Let $x^0, x^1,  \cdots, x^n\in\mathbb{R}^n$ and define $\delta^j = x^j-x^0$, $\gamma^j  = \nabla f(x^j)-\nabla f(x^0)$, $j=0,1\cdots,n$. Prove that the vectors $\{\delta^j\}_{j=1}^n$ are linearly independent, then   $$\overline{x} = x^n-[\delta^1\cdots \delta^n]\cdot[\gamma^1\cdots  \gamma^n]^{-1}\cdot\nabla f(x^n)$$ is a global minimizer of $f$   So, that's what I did:  $$\nabla f(x) = Qx-b^t\implies \gamma^j = Qx^j-b^t-(Qx^0-b^t) = Q(x^j-x^0)\implies\\\gamma^j = Q\delta^j\implies\delta^j = Q^{-1}\gamma^j$$  So  $$\overline{x} = x^n-[Q^{-1}\gamma^1\cdots Q^{-1}\gamma^n]\cdot[\gamma^1\cdots  \gamma^n]^{-1}\cdot\nabla f(x^n) =\\ x^n -Q^{-1}[\gamma^1\cdots \gamma^n][\gamma^1\cdots \gamma^n]^{-1}\cdot\nabla f(x^n) = x^n-Q^{-1}\nabla f(x^n) \implies \\\overline{x} = x^n-Q^{-1}(Qx^n-b^t) = x^n-x^n+Q^{-1}b^t = Q^{-1}b^t$$  So I need to prove $\overline{x} = Q^{-1}b^t$ is a global minimizer? Also, I need to use linear independence of $\{\delta^j\}$ to something. I guess it is related with the inverse matrix. Maybe linear independence of $\{\delta\}^j$ implies that that matrix has an inverse, but I don't know why.  Also, as I recall, $f(x)$ is quadratic and therefore convex. So shouldn't it has only one minimum? (therefore, since it is convex, it's the global?) So I should need to prove only that $\overline{x}$ is a local minimum? In that case I should only have to calculate $\nabla f(\overline{x}) = Q(Q^{-1}b^t)-b^t = 0$. The second derivative is just $Q$ and is definite positive. So: first derivative zero, second derivatie def. positive. Therefore this point $\overline{x}$ should be a minimum.  Even though I think I solved the exercise I don't know what all this means. It could just have asked if $Q^{-1}b^t$ is a global minimum. I think it is trying to show me a process of finding a global minimum for a quadratic function but I don't see the motivation.


I want to use Unity desktop environment on my modern Ubuntu 18.10 instead of GNOME Shell.  Which package should I install?

I recently installed Ubuntu 18.04 and I'm not keen on the desktop environment. I want the desktop env. I used to have in Ubuntu 14.04. How can I get it?  I've attempted to use , but when I try to install the Unity's 7.2.5 version using the command:  apt install unity=7.2.5   it gives me   E: Version '7.2.5' for 'unity' was not found   For sure I need to add a PPA for this, but which one!?


Is there an easy way to see the review menu on the mobile? or is it planned to add it.  In the past on my mobile I cheated by selecting the notification when you win the badge to review close vote, it bring to a non-mobile website layout.  Now I found the menu by following the 'full site' link at the bottom, after I can go review.   Let me know if there is an easy way ! (or if planned to add) Thanks

The other day I was looking at Stack Overflow on my Android phone. All is made very nice and all, but I could not find the Review button/link. Is it being implemented, did I miss it, or it is not available?


How to show that $f(X)=tr(X^{-1})$ is convex over the set of symmetric real positive definite matrices by showing that $g(t)=f(X+tV)$ is convex for any such $X$ and $V$? Clearly we need to show that $$g(t)\le (1-t)g(0)+tg(1)$$ but I'm stuck to find a simplified version of $tr((X+tV)^{-1})$. Thank you for your help!

Hi I would like to know whether the trace of the inverse of a symmetric positive definite matrix $\mathrm{trace}(S^{-1})$ is convex.  Actually I know that the trace of a symmetric positive definite matrix $S\in M_{m,m}$ is convex since we can find $B\in M_{n,m}$ such that $S=B^T\times B$ then we can write the trace as the sum of scalar quadratic forms, i.e. $\mathrm{trace}(S)=\mathrm{trace}(B^T\times B)=\sum_{j=1}^mb_j^T\times b_j$ where $b_j$ is the $j^{th}$ column of $B$.  for instance if we have  $trace([\begin{array}{cc} 1 & 2  \\ 3 & 4  \\ \end{array}] \times [\begin{array}{cc} 1 & 3  \\ 2 & 4  \\ \end{array}])= [\begin{array}{cc} 1 & 2  \\ \end{array}]\times [\begin{array}{c} 1   \\ 2   \\ \end{array}]+ [\begin{array}{cc} 3 & 4  \\ \end{array}]\times [\begin{array}{c} 3   \\ 4   \\ \end{array}]=30$  And so I wonder if $\mathrm{trace}(S^{-1})$ is convex too..


I’m trying to create a “secret” number finder without using a loop that counts from 1 to 10. Now what I am trying is to random out 10 numbers that if they are higher than the secret number in this case number 5 the loop will only look for number between 5 – 10 or if its lower 0-5.  Sometimes the function gives me an output that can look like this Higher: 0 Lower : 8 And then the error  Exception in thread "main" java.lang.IllegalArgumentException: n must be positive     at java.util.Random.nextInt(Unknown Source)     at test1.testvoid$TestVoidMethod.main(testvoid.java:31)   Otherwise  I can get the output  Higher : 1 The secret number is: 3   Without an error.   This is as far I get. I know this is a wot, but its hard to point out where the problem could be.   import java.util.Random;     public class testvoid {         public static class TestVoidMethod {             static int secretNumber = 3;             public static void main(String[] args) {                  Random randomGenerator = new Random();                 String result = "";                  int[] myIntArray = new int[10];                 int i = 0;                 int lastGuess = 0;                  result = checkWhichNumberThisIs(0);                   while (!result.equals("Equal"))                    {                     if(result.equals("Higher"))                     {          int randomInt = randomGenerator.nextInt(10 - (lastGuess - 1)) + lastGuess;                         lastGuess = randomInt;                         result = checkWhichNumberThisIs(randomInt);                     }                         else if(result.equals("Lower"))                     {                         int randomInt = randomGenerator.nextInt(lastGuess);                          lastGuess = randomInt;                             if(myIntArray.equals(randomInt)){                         result = checkWhichNumberThisIs(randomInt);                         }                     }                      myIntArray[i] = lastGuess;                     i++;                 }             }              public static String checkWhichNumberThisIs(int numberGuess) {                  String result = "";                  if (secretNumber < numberGuess) {                     result = "Lower";                       System.out.println("Lower " + numberGuess);                   }                   else if (secretNumber > numberGuess) {                     result = "Higher";                      System.out.println("Higher " + numberGuess);                    }                   else if (secretNumber == numberGuess) {                     result = "Equal";                      System.out.println("The secret number is: " + numberGuess);                   }                  return result;                 }             }      }

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


I am considering two options for installing Xubuntu 14.04.1 on my PC. I can install Ubuntu using  disc image, and then use the repositories to install the Xubuntu desktop.  The other option is to install Xubuntu using  disc image directly.  What are the differences between these two paths to getting the Xubuntu desktop on my PC? What are the pros and cons?

My question is what is difference between installing perticular desktop environment on Ubuntu And Using directly that (Default -environmented) distro/flavour of Ubuntu?  Example: Two options:   Install ubuntu-gnome-desktop or kubuntu-desktop or xubuntu-desktopetc. (official & recognized derivatives) alternatively on Ubuntu (Default -Unity Desktop) Use (Run) perticular distro/flavour Ubuntu-Gnome or Kubuntu or Xubuntu etc.   I want to know is both method working same performance? and which is proper method to use Desktop Environment.


When I was browsing through a stackexchange site recently, I noticed this:    As you can see, the tags  and  were showing through the spoiler section. The cause for this is that the spoiler css masks the color property of the tag, but not the background-color, so the blue background bleeds through. Here is an image of the css:  (It's quite small so you'll have to open it in a new tab and zoom in). As you can see from the strikethrough, the color is being overwritten by the spoiler but the tag is not.     This is an example of a spoiler. When this  is fixed, the tags  and  should not show through.     Please fix this by changing the css for spoilers to overwrite background color!

Tags in spoilers are always visible, even if you don't put your mouse on the spoiler (on  for example). See the screenshot:      Looks a bit strange on this site too:        that needs !


I need a help with this page layout:   top/bottom margins: 2cm for all pages on even pages: 3.5cm - 2cm on odd pages:  2cm - 2cm   I tried:  \setlrmarginsandblock{3cm}{2cm}{*} \setulmarginsandblock{2cm}{2cm}{*} \checkandfixthelayout   But  this doesn't resolve my problem. What's is the solution using memoir package?

in some (very rare) cases, it might be desirable to have the type area, particularly the text width, be different on even and odd pages. Let's say we're typesetting a textbook that's supposed to have small illustrations or annotations in the margin of the odd pages -- so we'd need a narrower type area on these. Like this:   Here's an attempt at a solution I came up with. It isn't as smart as I thought it was. I thought we might just combine everyshi and an \ifthispageodd test to change the typearea at every shipout. Obviously, that's not how it works:  \documentclass[paper=a5,pagesize,10pt,DIV=12,twoside=true]{scrreprt} \usepackage{everyshi,blindtext} \EveryShipout{% \ifthispageodd{\areaset{6cm}{12cm}}{\areaset{9cm}{12cm}}}  \begin{document} \Blinddocument \end{document}   this results in:  ! Bad space factor (0). <recently read> \@savsf   l.7 \Blinddocument   Is there a way to improve this? Or something entirely different?


So I have one male and one female dwellers that have high special. If I let them make a baby dweller do I get a good chance of getting a good baby dweller?

New dwellers seem to all start with very low starting stats.  Is there a way to get new dwellers with higher than normal stats?


Why functions are called methods in java. I am not asking the difference between the two. Why Java community choose to name them methods. Is there any concrete reason behind this decision or it's just a name? When i think of literal meaning as far as i could think function is related to internal working of some machine. Method is a way of working to achieve a goal(mathematical solution) or may be method is a way of implementing an Object. Is that where it came from or i just missed the real picture?

Can someone provide a simple explanation of methods vs. functions in OOP context?


I need to host a static website, single page deal, and instead of paying for hosting I thought I might use a cloud service, however an issue I can see of this is bandwidth allowance. Does anyone know which allows more bandwidth per link, Dropbox, Google Drive or another service?

This is a "catch-all" question designed to serve as an answer for all questions about choosing web hosting.  Pro Webmasters no longer accepts new questions about how to choose hosting.  All future questions pertaining to finding web hosting should be closed as a duplicate of this question. For more information about this policy please see .    How to find web hosting that meets my requirements?  What we're looking for in answers to this question are the basics about web hosting:   What is web hosting? What is the difference between shared, VPS, and dedicated hosting? How does a content delivery network relate to web hosting? Anything else you feel is helpful in finding a web host.   What we do not want is:   Endorsements or recommendations for specific web hosts We do not want your experience or other subjective information (just the facts please)


Hi I'm learning how to use terminal and I've created and image folder through terminal and now I'm wondering how I add an image that I already have saved on my computer by using terminal. I'm wondering if I can add an image to the folder without having to go through finder...

I have read about copying files with terminal but these examples will help me a lot. So here is what I want to do:  Examples:   I have a file in /home/levan/kdenlive untitelds.mpg and I want to copy this file to /media/sda3/SkyDrive and do not want to delete any thing in SkyDrive directory. I have a file in /media/sda3/SkyDrive untitelds.mpg and I want to copy this file to /home/levan/kdenlive  and do not want to delete any thing in kdenlive directory  I want to copy a folder from home directory to sda3 and do not want to delete any thing on sda3 directory and opposite I want to cut a folder/file and copy to other place without deleting files in that directory I cut it into.


Is there anyway to redirect filtered output to multiple files by running mycommand.sh only once?  Example output should be similar to this:  mycommand.sh | grep --line-buffered -B 1 A >> file1 ; my command.sh | grep --line-buffered -A 1 B >> file2   Or maybe with egrep somehow...

There are some commands which filter or act on input, and then pass it along as output, I think usually to stdout - but some commands will just take the stdin and do whatever they do with it, and output nothing.  I'm most familiar with OS X and so there are two that come to mind immediately are pbcopy and pbpaste- which are means of accessing the system clipboard.  Anyhow, I know that if I want to take stdout and spit the output to go to both stdout and a file then I can use the tee command. And I know a little about xargs, but I don't think that's what I'm looking for.  I want to know how I can split stdout to go between two (or more) commands. For example:  cat file.txt | stdout-split -c1 pbcopy -c2 grep -i errors   There is probably a better example than that one, but I really am interested in knowing how I can send stdout to a command that does not relay it and while keeping stdout from being "muted" - I'm not asking about how to cat a file and grep part of it and copy it to the clipboard - the specific commands are not that important.  Also - I'm not asking how to send this to a file and stdout - this may be a "duplicate" question (sorry) but I did some looking and could only find similar ones that were asking about how to split between stdout and a file - and the answers to those questions seemed to be tee, which I don't think will work for me.  Finally, you may ask "why not just make pbcopy the last thing in the pipe chain?" and my response is 1) what if I want to use it and still see the output in the console? 2) what if I want to use two commands which do not output stdout after they process the input?  Oh, and one more thing - I realize I could use tee and a named pipe (mkfifo) but I was hoping for a way this could be done inline, concisely, without a prior setup :)


\begin{figure}[h] \centering \label{fig:serviceworker} \includegraphics[width=\textwidth]{img/sw} \caption{Service workers en HTTP Requests} \end{figure}  In Figuur \ref{fig:serviceworker} wordt er getoond hoe de service worker als een brug functioneert tussen de website en de server waar de applicatie zijn data van haalt. Op deze manier kan de service worker toch nog informatie teruggeven aan de website als de verbinding met de server niet kan gemaakt worden. Dit zorgt er dus voor dat je de applicatie kan blijven gebruiken bij  geen of een slechte internetconnectie.   The problem is that the figure has number 3.1. But when I try to reference it in the text it shows as (Figure 3.2). What am I doing wrong here?

\documentclass{article} \usepackage{algorithm}  \begin{document} \setcounter{section}{54} \section{A section with no label} \begin{algorithm} \label{myalg} \caption{An algorithm with the label `myalg'.} \end{algorithm} Reference to myalg: \ref{myalg}. \end{document}   With this code, the reference givens 55 (the section number); if I move the label after the caption command, I get the correct reference (1).  Why should this be the case? I find it confusing: when thinking about an algorithm as an environment, you expect to be able to label it right after you began it. At the very least I would expect some kind of error or "??" to appear, rather than the previous environment or reference-able entity being used.


This really confused me, when I do a cat cmd, I always see something like % at the end of a file, but if I open the file on editor or sublime, it is gone. So how to make sure my file is in a correct format for example, run cmd cat -e test.txt abc$ sdf$ adg$ adsf$ afg%

I've noticed this on occasion with a variety of applications. I've often thought it was because the output was cancelled early (ctrl+c, for example) or something similar, and zsh is filling in a new line character. But now curiosity has gotten the best of me, since it doesn't seem to do this in bash.   zsh    bash    The Sequence program is something I pulled from a book while reading on Java certifications and just wanted to see if it would compile and run. I did notice that it does not use the println() method from the System.out package/class. Instead it uses plain old print().  Is the lack of a new line character the reason I get this symbol?


Here is a brief, self-explanatory bash session on Linux:  $ env | grep LD_LIBRARY_PATH $ export LD_LIBRARY_PATH=foo $ env | grep LD_LIBRARY_PATH LD_LIBRARY_PATH=foo $ echo $LD_LIBRARY_PATH  foo   Here is the same session on a Mac:  $ env | grep LD_LIBRARY_PATH $ export LD_LIBRARY_PATH=foo $ env | grep LD_LIBRARY_PATH $ echo $LD_LIBRARY_PATH foo   Notice that, oddly, env does not include LD_LIBRARY_PATH, even though it has been exported, and echo finds it. But it's not just an env thing. Other programs cannot find the environment variable. Here is a JVM (via the Scala REPL), after setting export LD_LIBRARY_PATH=foo:  scala> System.getenv("LD_LIBRARY_PATH") res0: String = null  scala> System.getenv("SHELL") res1: String = /bin/bash   On Linux, System.getenv("LD_LIBRARY_PATH") yields the expected foo.  I'm trying to execute an external process from Scala that needs to inherit LD_LIBRARY_PATH from the parent shell. But if the JVM can't see the parent shell's LD_LIBRARY_PATH, and doesn't inherit automatically, it's hard to get right.  On Linux everything works as expected.  Thank you for your help!

In shell scripts used for unit testing with dynamic libraries in a directory other than the typical @rpath, I have previously been able to set DYLD_FALLBACK_LIBRARY_PATH to set the directory containing the libraries. Under 10.11.1, bash seems to ignore attempts to set this environment variable:  $ sh -x testscript.sh + DYLD_FALLBACK_LIBRARY_PATH=/Users/something/testinglibs + export DYLD_FALLBACK_LIBRARY_PATH + exec printenv   and DYLD_FALLBACK_LIBRARY_PATH is not present in printenv's output.  Is this a security-related hack in 10.11's shell? I haven't been able to find this change documented in man pages or online.


I know from the axiom of regularity that the set $\{\{\{\ldots\}\}\}$ cannot exist in ZFC.  Is there another set theory where it's possible ? If yes, how would we construct it ?

Ignoring the axiom of regularity (and therefore the implication of "no set can contain itself"), would it be correct to state that the set that contains only itself is unique?  My argument is that if $x$ is said set, then $$ x = \{x\} = \{\{x\}\} = \{\{\{\cdot\cdot\cdot\}\}\} $$ Ad infinitum, which seems to be unique.


I find SRIMA model (0,1,1)*(1,1,1)[12] to fit my time series model but i don't know how to write the model with mathematical way. I need help.

I'm trying to write a seasonal ARIMA model ARIMA(1,0,3)(1,2,0) period 5 mathematically but I don't seem to be able to follow what this resource is saying   The example they use is ARIMA(1,1,1)(1,1,1)4 so it makes it very hard for me to follow what's actually going on because all the numbers are the same.  Could someone help me write out my model mathematically and possibly explain how it's done?


First of all I haven't enabled the overclocking anywhere yet, how can my cpu work at its Overclock frequency?(4.4 Ghz as you can see on the screenshot bellow!) and if that is the case why it's called overclocking since I can't manage the throttle, that's not gonna age the cpu faster since this is not its base frequency, and my cpu is literally clocking 4.4 right now??, just like a cpu with the base frequency of 4.4?  Second, I just started up the windows 10(Fresh Factory-Reset, Bare metal) with one PotPlayer and Micrsoft Word, with no game running, why 7.3 GB of my memory is already occupied.  Third, I have one Intel GPU and one NVIDIA Quadro T2000, Windows can use them at the same time? So if I run a GPU intense program, it will be multi threaded through the both GPU's pipelines?

I just got a new Intel CPU, and the specifications say 3.5GHz but with turbo boost to 3.9GHz. What does Intel Turbo Boost do? From the description it sounds like they are saying "The road's speed limit is 100 km/hr, but if you get to that speed then the new speed limit is 140 km/hr". Why not just set the clock speed to 3.9GHz to start with? So what is Intel Turbo Boost actually doing?


I have an android phone and use chrome. I have the stack exchange app. But I happened to be googling and went to the stack exchange via chrome. A pop up came up that asked me whether I would prefer to use chrome or the stack exchange app whenever I click on a stack exchange link.   Unfortunately, I accidentally set it so that it always chooses chrome. Really, I would prefer to be asked each time. Is there a way to reset this?

I used the ADWLauncher EX by default while having Gingerbread 2.3.6.  Today I have manually updated my Nexus S to Ice Cream Sandwich 4.0.3, and I wanted to give the new default launcher a shot, but I cannot find anymore where to select / forget the default application for an action.  I've turned the settings of my phone inside out, googled and crawled the forums, but without success. If anybody can tell me how to change a default application in ICS, I'd be grateful!      Yeah, I never thought I'd want to see that Complete action using... window again! :D


On the last page of , the following statements are made (I'll jump right to around the point of interest):  Example: Consider $A=p_x$, $B=x$. Then  $$\langle A\rangle=\langle B\rangle=0;\,\,\,\Delta A=\sqrt{p_x^2},\,\,\,\Delta B=\sqrt{x^2}$$ $$[x,p]=i\hbar\implies C=\hbar=\langle C\rangle$$ $$\Delta p_x \Delta x \geq \frac{\hbar}{2}$$ For the minimum uncertainty state we have, $$p_x\psi = \frac{i\hbar}{2(\Delta x)^2}x\psi \tag{1}$$ With $p_x=i\hbar\frac{d}{dx}$, the solution to the differential equation gives $$\psi(x)=\frac{1}{\sqrt[4]{2\pi(\Delta x)^2}}e^{-\frac{x^2}{2(\Delta x)^2}}$$  It's clear that notation is being abused like Matilda, but putting that aside I can't see where equation $(1)$ came from. This looks like a good proof that Gaussians make HUP into an equality, so I would very much appreciate if you could help point me in the right direction.

Can anyone point me to a reference (preferably either something online or something a small liberal arts school would be likely to have in its library) that goes through a derivation of the minimum uncertainty wavefunction in more detail than in the Griffiths?  Edit I've moved the second part of my original question to a separate post:


I am finding it hard to find a detailed step by step process. Do I have to make a truth table?  Workings so far: I can guess that I would need 2 4-16 decoders, which share the 5 inputs of the required 5-32 decoder, and gives 32 outputs. But that leaves me with 1 extra input that I can't cater to, where is it going to come from?

I have an idea of how to get started, but not sure where to go from there.  Since I am using two 3-8 decoders to develop a 4-to-16 decoder, I want to use 4 inputs out of the two 3-8 decoders.  So I'll use all three of the first and the first of the second, and connect the last two inputs to ground, since they won't be used.  Any pointers on where to go from here are appreciated.


I'm peeking through some shell scripts - what's the purpose of the x in the comarison shcu as   if [ "x$USER" != "x$RUN_AS_USER" ]; then         su - $RUN_AS_USER -c "$CATALINA_HOME/bin/startup.sh"  else         $CATALINA_HOME/bin/startup.sh  fi

I see this often in the build scripts of projects that use autotools (autoconf, automake).  When somebody wants to check the value of a shell variable, they frequently use this idiom:  if test "x$SHELL_VAR" = "xyes"; then ...   What is the advantage to this over simply checking the value like this:  if test $SHELL_VAR = "yes"; then ...   I figure there must be some reason that I see this so often, but I can't figure out what it is.


I'm looking for a script to automatically back up files from a connected USB drive, with a pre-defined file extension, to a local directory on my machine. The script given in the top answer in  basically provides what I am looking for, except that it doesn't provide a way to limit it to files of a certain type. My programming knowledge is limited, I don't know how I would go about modifying the script to suit my needs and was hoping that someone might have a solution. Cheers

I have a growing music collection which I manually keep in sync with an external USB drive. Sometimes I edit their ID3 tags, add or delete a file in either the hard drive or the USB drive, and I would like to keep those changes synchronized between both.  Does Ubuntu has something available that would help me with this scenario? Preferably something easy to use with a UI.  Update: To clarify my question, changes may happen on both the local hard drive or the USB drive, so the sync process must be on both directions.


I did assume that the answer was yes, but I have developed some doubts about that because I observe something which seems to contradict:  I have a netlayer containing road segments (LineStrings) with a corresponding spatial index netindex. Now I wish to find the closest segment to a given QgsPoint pt.  I use the netindex.nearestNeighbor(pt,n) to obtain the corresponding featureIds:  req = QgsFeatureRequest();  req.setFilterFids(netindex.nearestNeighbor(pt,n)) fs = [f for f in netlayer.getFeatures(req)] closestEdgeGeoms = [f.geometry() for f in fs] ptGeom = QgsGeometry.fromPoint(pt) dists = [g.distance(ptGeom) for g in closestEdgeGeoms]   Now let's have a look what the dists are for increasing n:  n=1 # -> dists=[132.57922743885197] n=2 # -> dists=[44.65094179417814, 132.57922743885197], ups!? n=3 # -> dists=[232.91196346783073, 44.65094179417814, 132.57922743885197] n=4 # -> dists=[186.9821211234746, 232.91196346783073, 44.65094179417814, 132.57922743885197], again found sth closer... ...   That's it. Does someone have an idea how large n should be to guarantee to catch the closest geometry? Or is this a bug?    Edit: As  pointed out  is related. My question is actually answered by  answer.

I'm trying to get the closest line to a point using PyQGIS in a plugin. The active code file is this:   When I request the closest line (only 1)  nearestIds = self.spIndex.nearestNeighbor(self.feat2.geometry().centroid().asPoint(),1)   I sometimes get a list with two lines and the first one is not the closest but as far as I can see the second one is. Why is this?   Does QgsSpatialIndex use only boundingboxes for lines? How do I get the real closest line always, not only most of the time?


A cartoon in which gems turn into monsters. I remember a monster that can use vine whip and he had a horn he had a green gem, this is not Pokémon. The cartoon was based in magical world. In the first episode a girl steals a book. I believe this show was on cartoon network.

What is the name of the anime TV show where a boy can summon beasts with crystals/gems. It was on SABC 2. There was also a boy that could summon a purple turtle . I think the gems were blue, green, and red.


There is often information “hidden” in the data that is not readily evident.  What does it mean by "readily evident"?

A  asks whether the modifier "clearly" changes the meaning of "evident". I would have said, prior to examining a few dictionaries, that evident did not necessarily mean readily apparent, but to my surprise it does.  This brings me to ask what word or expression would mean something can be taken as a true fact, but not through an easily constructed (not obvious or readily apparent) rationale?   For example, if Sherlock Holmes says something is true while everyone else is still sitting on their hands, then it is evident to Holmes, but not to the rest of the world. So, from everyone else's point of view, it is not readily apparent, and (by definition) apparently it is not evident, clear, or clearly evident at all, based on the dictionary definitions. But (let's stipulate) it is true and deducible from the observable evidence. What would we call this?  Update  An update is highlighted above. I can see from some of the answers and comments that I may have gone off my mark with the phrase "not through an easy-to-follow rationale”, and I have modified the question to correct this. I understand that there can be rationales, arguments, or proofs that, once explained, may or may not be easy to follow. What I intend is that the rationale to support the indisputable conclusion is not (initially) easy to recognize or construct (not readily apparent) in the first place. I apologize for the confusion. (The original can be seen in the change history.)  Update 2  Shortly after offering a bounty to this request, I recalled a single word that I now believe is a very good match to the parameters specified in this inquiry as it is stated above. That word has not yet been suggested (or approached) by any answer or comment (active or deleted) at the time of this edit. This request is changed to a single word request. (However, if you feel a single word fits well but not without some additional supporting words, please offer your thoughts in an answer.) While my curiosity for the term has already been met, the request and bounty remain as an open challenge. I will post my own answer once the bounty has expired and been awarded.


I need to write an WPF application, that can be launched as default application at doubleclick on the file with extension .specext in files explorer.  The problem appears... at the beginning. I don't know where can I find the file content or even the information, that the application was launched on opening the file.  Where should I start searching? How to get this file content?  Edit:  I know how to associate file with an application. I don't know how to display its' content when the application is launched.  Edit 2 (solution):  Currently I'm using Environment.CommandLine to get the file path.

I'd like to to associate a file extension to the current executable in C#. This way when the user clicks on the file afterwards in explorer, it'll run my executable with the given file as the first argument. Ideally it'd also set the icon for the given file extensions to the icon for my executable. Thanks all.


My Macbook Pro ( Retina 13 inch early 2015), all of a sudden, started showing "Condition: Replace Now" on battery. Everything was working fine till last night; when I turned on the laptop in the morning, it asked me to restore the work (as if it was crashed when I turned it off at night).  The laptop was slow, and I noticed this "Condition: Replace Now" on battery status. I shut down the laptop, rebooted, did SMC reset, PRAM reset, but its still showing the same. The battery is showing 0% when I remove the charger the laptop turned off. And when its off when I connect the charger its starts the laptop.   My battery cycle is just 385. I am running macOS Sierra. Can anyone please advise what is the workaround to fix this.

Model: MacBook Pro Retina, 13-inch, Early 2015 While I was working, I didn't realize that the battery was low and as a result, my MacBook Pro shut down when the battery had no power. So, then I plugged in the charger and powered it on. This time I noticed something was strange. The battery was stuck in 0% for like around 10 minutes and the date got reset to 1st January 2017. I tried resetting NVRAM. Nothing happened. So, then I ran diagnostics and I got this as a result:  Here's the battery information:  Here's a screenshot from Battery Health:  Now it is pretty obvious that you might ask me to change the battery because the screenshots say so, but I want a final opinion from you guys what to do next. Everything was working fine and all of a sudden this happens. I feel if I plugged the charger in time, I wouldn't have to see all this. And also a new battery isn't exactly affordable for me at the moment. And it is also important to note that while the charger is on, it shows orange LED. So, what should I do?


Are there any books or references that exhaustively list cross-sections for various processes in QED or particle physics? I think such a book would make for a very useful reference, and in particular I would like to practice deriving cross-sections.

Where to find cross section data for $e^{-}$ + $p$ $\longrightarrow$  $p$ + $e^{-}$ ?  does not include it.