I'm not sure trig identity to use. Would we use $1+\cot^2(x) = \csc^2(x)$? I know that we break down into $\csc^2(x)$ and $\csc(x)$. Could I get hints?


request.onreadystatechange = function () {   if (this.readyState === 4) {     var nav = this.responseText;   } };  -->use nav here<--  How can I use my variable nav outside this function without being undefined?


Identicons changed on profiles (but not posts)

It seems that users who have auto-generated identicons as profile images are showing different images on their profile vs on posts. The images shown on posts and in chat are the regular images that have always been, but on profile pages, and reputation leagues, I am seeing different new images. Also seems that the network profile shows the original image but per-site profiles are showing the new image.  Weirdly, other people don't seem to be seeing this (after asking in chat), but I do even when I'm not logged in and on different network connections. I've only looked at a handful of accounts but all the ones I have checked are showing the same inconsistency.        Some affected profiles:


I believe this to be fraud — hired, then asked to cash check and send cash as Bitcoin

I have been "hired" by Nissan Motor as a key account specialist.  My first assignment is to cash two checks that I have received. Both were written by a customer who has already received the engines. The total is $2500. I am to cash the checks, get the money, take out my bonus and any other related expenses and deposit into a Bitcoin ATM. Then make copy of receipt and electronically send to my "manager".  I contacted a lawyer, was told to talk to the Department of Labor, who said they will not get involved, as this is between me and my employer. Any advice?


Why do I have two docks in Ubuntu desktop (with GNOME 3) after installing Dash to Dock?

What's going on here? I've installed the  on Ubuntu 17.10. Everything was cool, and as I was trying to hone and tweak the look of my desktop, at some point the shortcuts bar (dock?) on the left is duplicated.  (Click image to enlarge) The default, which normally disappears with Dash to Dock, is there underneath the one that usually shows up when I install Dash to Dock. Why? I've tried to go through the options for Dash to Dock, the GNOME Tweak Tool, and the regular Ubuntu settings, but I can't figure it out.


How can I recover lost, erased, files from Hard disk bad shut-down. Free apps only please. MacBook.I had a bad shut down, then restarted system. I lost bunch of docs, pics, music


Remove any number and the remaining numbers can be partitioned into two subsets of equal sum; prove all numbers are equal.

Supposed I have a list of $n$ real numbers, where $n$ is odd. The list is constructed such that I can remove any arbitrary number from the list, and the remaining numbers can be partitioned into two equal-sized subsets with equal sums. Prove that all numbers in the list are equal.   This should be somehow related to linear algebra. A way I could think of to interpret this is that the list is essentially a $1 \times n$ row, and there exist $n$ $n \times 1$ vectors with one zero in some entry and $1$'s and $-1$'s in other entries with the entries summing to $0$, such that the product of the row and the column vector is $[0]$.  In other words, the entries/$1 \times 1$ columns in the row are linearly dependent once we remove any arbitrary entry/column. I'm not sure how this is/could be related to the proof though.  Thanks in advance!


How do I upgrade a hardware driver with no internet connection. can I do it from a usb stick?

I installed a new pci card into my pc and it does not work.  It is a new version of old card so I think I need to update my drivers for this card.


Differnce between a function and a sequence

What is the difference between a function and a sequence? I have googled it but I have not found any solid answer anywhere.


Importance of setting cpu architecture type in Visual Studio C#

Is it really important to specify architecture type if I'm making a simple Windows program that utilizes HttpWebRequests, or is it ok to leave it as "Any CPU"?


How to tell Chrome what to do with a magnet link?

Right now Chrome throws its apron over its head and calls Firefox, which opens the link with rtorrent.  What do I need to do to eliminate the Firefox step?


I have an AJAX callback function inside my functions.php file, which displays posts in a specific category.  add_action( 'wp_ajax_ajaxified_function', 'ajaxified_function' ); add_action( 'wp_ajax_nopriv_ajaxified_function', 'ajaxified_function' ); function ajaxified_function()  {      $post = get_post($_POST['post_id']);     $feat_image = get_the_post_thumbnail($post->ID);     $desc_values = get_post_custom_values("designation",$post->ID);     $title = current(explode(' ', get_the_title($post->ID)));     if( is_array( $desc_values ) )     {      foreach($desc_values as $key => $value );     }        $email_values = get_post_custom_values("email",$post->ID);     if( is_array( $email_values ) )     {         foreach($email_values as $key => $email_value );     }     echo '
'.$feat_image.'
'.$post->post_.'
'.$post->post_title.'

'.$value.'

Email '.$title.'

'.$post->post_content.'
';      echo '';        echo '

';                 echo do_shortcode('[contact-form-7 id="698" title="Meet The Team Email"]');             echo '

';       die();   }   When I use this its just echoing the shortcode instead of showing the contact form.  I am working on local now. I have a demo which just uses just   You can see a Email link in the biography div. On clicking on that link I want to show a colorbox with the contact form.


Should I use 'is' or 'are' in ambiguous sentences like this one?

I understand that you should use 'is' for singular and 'are' for plural, but in this sentence I am not sure which applies. Take the sentence  Bees are an important part of our ecosystem.  Let's say I wanted to reword it so that the subject is at the end of the sentence. Which of these two is correct?  An important part of our ecosystem are bees.   An important part of our ecosystem is bees.  To me they both sound wrong, so I want to know how I can determine correct grammar in these cases.


If we see only the reflected colour, how coloured shadows are of same colour?

We know, for instance, if something is blue, it is because it is absorbing all other wavelengths of coloured light and reflecting the blue colour. But when we pass a white light through a  coloured translucent object, the shadow it forms, contains the hue of the same colour. If the blue light has been reflected, and absorbed light is everything but blue. Why is it so? Also, is this phenomena related to some specific number of boundaries and mediums light has to go across?


Moving inside identifier-words (underscore, camelcase) in vim

I would like a quick way to move between parts of a word e.g.:  this_is_a_variable_name ^    ^  ^ ^        ^  thisIsAFunctionName ^   ^ ^^       ^     This would increase the speed in certain situations when only part of the word needs to be modified / deleted e.g.:  +--------+----------------------+------------------+---------------------+ | change | k_error_write_stream | sendAckMessage   | printMessageAndExit | | to     | k_error_read_stream  | sendReplyMessage | printMessage        | +--------+----------------------+------------------+---------------------+


Apache serving modified static assets incorrectly: serves obsolete file with sizes adjusted to match that of the new file

I've got a CakePHP project running in a CentOS VirtualBox. The website is served with Apache 2.2.15.  There are JS files in the document root folder. Apache seemed to serve them file.  But after i edit a JS file, Apache would serve the old file. It will modify the size of the old file to match the size of the new file and serve the modified old file:   If the new file is smaller than the old file, it would cut the old file and serve the result; If the new file is larger than the old file, it would append � symbols to the old file and serve the result.   Restarting Apache does not resolve the issue.  The only way i found to make Apache serve the current file is to move the file to another location. Then CakePHP will display a fancy 404 page. Then i move the file back, and Apache displays the file in it's current state.  But i2.2.15t will freeze the file in that state and after modifying the file again i will have to repeat the trick again.  Apache logs are clean, the access log file displays this:     172.28.128.1 - - [12/Jul/2014:07:42:13 -0400] "GET /assets/js/compiled/editable_group.js HTTP/1.1" 200 903   What is the reason of the problem and how do i resolve it?  PS I will be happy to provide any details, logs, configs, etc. Just tell me what you want to see.


What are good initial weights in a neural network?

I have just heard, that it's a good idea to choose initial weights of a neural network from the range $(\frac{-1}{\sqrt d} , \frac{1}{\sqrt d})$, where $d$ is the number of inputs to a given neuron. It is assumed, that the sets are normalized - mean 0, variance 1 (don't know if this matters).  Why is this a good idea?


Prove that if $(ab)^i = a^ib^i \forall a,b\in G$ for three consecutive integers $i$ then G is abelian

I've been working on this problem listed in Herstein's Topics in Algebra (Chapter 2.3, problem 4):     If $G$ is a group such that $(ab)^i = a^ib^i$ for three consecutive integers $i$ for all $a, b\in G$, show that $G$ is abelian.   I managed to prove it, but I'm not very happy with my result (I think there's a neater way to prove this). Anyway, I'm just looking to see if there's a different approach to this.   My approach:  Let $j=i+1, k=i+2$ for some $i\in \mathbb{Z}$.  Then we have that $(ab)^i = a^ib^i$, $(ab)^j = a^jb^j$ and $(ab)^k = a^kb^k$.  If $(ab)^k = a^kb^k$, then $a^jb^jab =a^jab^jb$.   We cancel on the left and right and we have $b^ja = ab^j$, that is $b^iba = ab^j$.  Multiply both sides by $a^i$ on the left and we get $a^ib^iba = a^jb^j$, so $(ab)^iba = (ab)^j$. But that is $(ab)^iba = (ab)^iab$.   Cancelling on the left yields $ab=ba$, which holds for all $a,b \in G$, and therefore, $G$ is abelian.  Thanks!


My system has 2 OS: Win 7 x64 and Ubuntu 12.10. I'm getting 2 Windows boot options: "on dev/sda1" and "on dev/sda2". What does this mean? What implications does this have for my continued Windows usage and for when I may remove the Ubuntu installation later?  Longer: I was running just Win 7 x64, then installed Ubuntu 12.10 along side it. Was trying to boot back to Windows 7 only to get a "disc reading error." Booted back to Ubuntu, grabbed boot-repair, then used mbr repair in boot-repair. System could then boot back to Windows but in fact always did so directly, i.e. always by-passed Ubuntu. Then I used the Ubuntu LiveCD to get boot-repair and used the "Recommended" repair option. Now everything works normally except for the issue described here. Both Windows options in Grub boot to the same Win installation I had previously.  p.s. Running "sudo update-grub" maintains both the Windows options.


Are gravitons bound by the event horizon?

I understand that photons, even when traveling at the speed of light, cannot escape the event horizon of a black hole.  Are gravitons and other virtual particles traveling at the speed of light also confined by event horizons?  If so, it seems that the gravitational field created by the black hole would result only from the mass of the black hole beyond the event horizon, where gravitons are capable of escaping.  As a result, would  there would be a disparity between the apparent mass of the black hole due to its gravitational field on other celestial bodies and the total amount of matter contained within the black hole?   Also, I was reading this question: , which suggests that gravitons and curved space may be indistinguishable.  However, if gravitons are bound by the event horizon it seems that a black hole would act differently based on whether gravity results from gravitons or curved space-time.  The existence of bound gravitons would negate the gravitational field of mass within the event horizon, resulting in a significantly lower gravitational field outside of the black hole.  Would this occur, or am I neglecting some effect of relativity upon the gravitational field?


Gaussian curvature and geodesics. Can such a surface have non vanishing curvature?

Consider a surface diffeomorphic to a cylinder (the boundary is 2 curves diffeomorphic to circles). Suppose the boundary curves are geodesic, can the surface have non-vanishing gaussian curvature (i.e. $K \neq 0$ everywhere)?  I tried to use the Gauss-Bonnet theorem, but I'm not sure how.


Wrong (generic) Mac dock application icon

I have the following problem since upgrading to OS X 10.13.1 High Sierra on MBP 2017.  A generic icon is shown for nearly all my apps. See the image below. Does anyone know how to fix this and get the applications icons back?


What's the current state of LaTeX3 (2020)?

There are a few questions on this forum asking about why Latex3 is taking so long to come out. However, all of these are from the early 2010s. I'm just wondering what the current state of the project is and whether it's ready (or nearly ready) for prime time?


Birthdate field in bio does not allow older than 94 years?

I notice that entering an old date in the "birthdate" field returns the error "Date must be later than 1920/01/01" which is actually not true, because you can enter a date of 1920/01/01.  Also, are the developers assuming no one on the site is older than 94? I know that SAS database dates have a range begin at 1920. Tell me they are not using SAS to power Stack Exchange.


I am trying to find a way where I can read a local text file using java script. am aware of file reader API however I want to do this in IE7 and the filereader is for IE10 above. Been searching the web and not many good solutions come up? any ideas?   thanks


My Apache 2.2 is running on port "8080" I want to call my site url http://www.example.in:8080/abc/xyz.html/index.php  (xyz.html is a folder)    as ....  http://www.example.in:8080/abc/xyz.html  Can any one help me with the .htaccess for this..


I would like to have bold enumerate labels that both have a Roman numeral and a custom text in them, like on page 26 (pdf page 2) of .    I'm using the following code to just have bold Roman numerals (using enumitem), but I can't figure out how to add custom text.  \documentclass{article} \usepackage{enumitem} \begin{document} \begin{enumerate}[label=\textbf{\Roman*}]     \item item one.     \item item two. \end{enumerate} \end{document}   How can this be done?


OpenLayers: transfer from custom projection to map projection

I am building a web application with OpenLayers that contains a map that allows insert, edit and remove points, my map is now using “EPSG:4326" projection.  I have shapefiles and xlsx files that contain polygons and points that I need to insert as layer in the map.  The problem is that the shapefiles use EPSG:2309 projection, this is Israel tm grid projection that OpenLayers doesn't recognize.  How do I transfer these points/polygons to the EPSG:4326 projection?  I found this:  But I don't know if its can be helpful, or how...


Posting and answering questions you have already found the answer to

Sometimes you spend a day or more solving a technical problem, and when you finally solve it, you may want to post it on your blog (if you have one) to share with the community.  However, most developers don't have a lot of time to update their blogs, and that is why personal blogs are not ranked very highly on Google/Bing.  So even if you describe a brilliant idea, chances are that, except a few of your friends, nobody will ever find it. This is a common reason why some developers start their blogs and soon give up; it is not interesting to write for the community if you have no feedback on your posts.  Unlike personal blogs, Stack Exchange sites are highly ranked in Google (I was amazed when I saw that a question asked on SO just an hour ago appeared 3rd in my Google search!), so if your question and answer are valuable for others, they will be rated highly and will be visible for other developers.  With this in mind, is it good practice to post a question and answer it yourself immediately when you want to share an idea with the community?


I would like to ask for advice how to solve a problem i am having with my mail server.  I have  I have a problem to send emails from my mail server using my web sites.  every time i am trying to sendemail from my site i get this error:  Mailbox unavailable. The server response was: Authentication is required for relay  can anybody advice me how to fix it in a way that all emails thas are going out from my web server are allowed to be send.  My Code Fro Sending Email is :  MailMessage MyMailMessage = new MailMessage(); MyMailMessage.From = new MailAddress("xxx@gmail.com"); MyMailMessage.To.Add("xxx@gmail.com"); MyMailMessage.Subject = "Inquiry Form"; MyMailMessage.IsBodyHtml = true; MyMailMessage.Body = "Hello"; SmtpClient SMTPServer = new SmtpClient("mail.DomainName.com");  SMTPServer.Port = 25;  SMTPServer.Credentials = new NetworkCredential("UserName", "Password"); SMTPServer.EnableSsl = false;  SMTPServer.Send(MyMailMessage);   Also i have code in Web.config file :   <system.net> <mailSettings>   <smtp from="mail.domainname.com">     <network host = "mail.domainname.com" userName ="xxxxx" password= "xxxxx" />   </smtp> </mailSettings>


Regular expression for invalid characters in XML

I am trying to figure out a way where I can find all the invalid characters in an XML.  According to  these are the valid characters in an XML:  #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]   Converting it to decimal:  9 10 13 32-55295 57344-65533 65536-1114111   are the valid xml characters.  I am trying to search in notepad++ using the appropriate regular expression for the invalid characters.  A snippet from my XML:          <custom-attribute attribute-id="isContendFeed">fal &#11; se</custom-attribute>         <custom-attribute attribute-id="pageNoFollow">fal &#3; se</custom-attribute>         <custom-attribute attribute-id="pageNoIndex">fal &#13; se</custom-attribute>         <custom-attribute attribute-id="rrRecommendable">false</custom-attribute>   From the above example I want that my regular expression finds &#11; and  &#3; for me because these are not allowed in an XML.  I am not able to construct the regular expression for this.  The regular expression I made for the numeric ranges:  32-55295 : (3[2-9]|[4-9][0-9]|[1-9][0-9]{2,3}|[1-4][0-9]{4}|5[0-4][0-9]{3}|55[01][0-9]{2}|552[0-8][0-9]|5529[0-5]) 57344-65533 : (5734[4-9]|573[5-9][0-9]|57[4-9][0-9]{2}|5[89][0-9]{3}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-3]) 65536-1114111 : (6(5(5(3[6-9]|[4-9][0-9])|[6-9][0-9]{2})|[6-9][0-9]{3})|[7-9][0-9]{4}|[1-9][0-9]{5}|1(0[0-9]{5}|1(0[0-9]{4}|1([0-3][0-9]{3}|4(0[0-9]{2}|1(0[0-9]|1[01])))))))   These regular expression are working if used separately but I am not able to make the complete regex.  Is there any other way other than the regular expression by which I can find the invalid characters? If not, please help me in constructing the regular expression which can find invalid characters present in my XML.


Personally, I have a tendency to write politely when I post questions, given the fact I'm asking for help.  I noticed that many times, when editing a question I wrote, the editor deletes the opening 'Hi' or the closing 'Thanks' etc. Is there a real reason to remove curtsies?  I appreciate your thoughts on the subject.  Edit  I got the point from the answers so far. I suppose I'll stop using greetings and thanks, if that's the site's spirit.


Can a Bristling Hydra activate Hexproof when an instant is cast?

I summoned the  and it was killed instantly before I declared I was making it Hexproof. Could I have prevented it's death if I had said it was Hexproof before the other player cast his spell?  The additional reason for asking this is due to the energy production of the card and the energy requirement for playing the ability.  When bristling hydra resolves it provides 3 energy and the ability requires 3 energy therefore this question has some additional implications about how the spell could potentially resolve i.e. does the energy resolve in time for the player to use the ability or do you need an additional source of energy


Prove that $\int_a^b \left( \int_c^d f(x,y)dy\right) dx=\int_c^d \left( \int_a^b f(x,y)dx\right) dy$

Let $f$ be continuous function on $[a,b]\times [c,d]$. Prove that      Prove that $$\int_a^b \left( \int_c^d f(x,y)dy\right) dx=\int_c^d  \left( \int_a^b f(x,y)dx\right) dy$$   First of all, note that $ \int_c^d f(x,y)dy$ is continuous in $x$ and $ \int_a^b f(x,y)dx$ is continuous in $y$ so both integrals exist.  We have  $$\frac{d\left[\int_a^b \left( \int_c^t f(x,y)dy\right) dx \right]}{dt}=\int_a^b f(x,t) dx$$  (We used differentiation under the integral sign and the fundamental theorem of calculus)  Also  $$\frac{d\left[\int_c^t  \left( \int_a^b f(x,y)dx\right) dy \right]}{dt}=\int_a^b f(x,t) dx$$  (Here we used the fundamental theorem of calculus)  Thus $$\int_a^b \left( \int_c^t f(x,y)dy\right) dx-\int_c^t  \left( \int_a^b f(x,y)dx\right) dy$$  as a function of $t$ is constant on $(c,d)$.  It remains to show that this constant is $0$. How can I do this?


Noether's current expression in Peskin and Schroeder

In the second chapter of Peskin and Schroeder, An Introduction to Quantum Field Theory, it is said that the action is invariant if the Lagrangian density changes by a four-divergence. But if we calculate any change in Lagrangian density we observe that under the conditions of equation of motion being satisfied, it only changes by a four-divergence term.  If ${\cal L}(x) $ changes to $ {\cal L}(x) + \alpha \partial_\mu J^{\mu} (x) $ then action is invariant. But isn't this only in the case of extremization of action to obtain Euler-Lagrange equations.   Comparing this to $ \delta {\cal L}$  $$ \alpha \delta {\cal L} = \frac{\partial {\cal L}}{\partial \phi} (\alpha \delta \phi) + \frac{\partial {\cal L}}{\partial \partial_{\mu}\phi} \partial_{\mu}(\alpha \delta \phi) $$  $$= \alpha \partial_\mu \left(\frac{\partial {\cal L}}{\partial \partial_{\mu}\phi} \delta \phi \right) + \alpha \left[ \frac{\partial {\cal L}}{\partial \phi} - \partial_\mu \left(\frac{\partial {\cal L}}{\partial \partial_{\mu}\phi} \right) \right] \delta \phi.    $$   Getting the second term to zero assuming application of equations of motion. Doesn't this imply that the noether's current itself is zero, rather than its derivative? That is:  $$J^{\mu} (x) =  \frac{\partial {\cal L}}{\partial \partial_{\mu}\phi} \delta \phi .$$  I add that my doubt is why changing ${\cal L}$ by a four divergence term lead to invariance of action globally when that idea itself was derived while extremizing the action which I assume is a local extremization and not a global one.


.NET: Which Exception to Throw When Required Property is Not Set?

Assume I have a class like this:  public class Foo {     public Bar RequiredProperty { get; set;}      public void Baz()     {         if (this.RequiredProperty == null)         {             // Which exception should I throw?         }     } }   My solution has a class that is designed to be reused without having to pass a lot of arguments to the Bar method over and over again. So, what should I throw when Bar isn't initialized to a non-null value?  More Information I'm essentially rolling my own code parser and formatter. Call it an object lesson. One of the classes is an HtmlCodeFormatter that has the following properties (in honor of Dependency Injection):  public IFormatter Formatter { get; set; } public IParser Parsre { get; set; }   This allows me to write any number of language-specific parsers and formatters. For example, I have a CSharpParser and a JavascriptParser. I also have an HtmlCodeFormatter, and there are plans for another (of dubious utility).  The idea is that you can instantiate the HtmlFormatter using an object initializer, like this:  var formatter = new HtmlCodeFormatter()     {         Parser = new CSharpParser();         Formatter = new HtmlCodeFormatter();     }; formatter.Format("Console.WriteLine(\"Hello, world!\"));   When HtmlCodeFormatter.Format is invoked, it needs to be able to verify that both a parser and a formatter have been provided. That's no problem, really, but I'm kind of stumped about which exception to throw. I'm leaning towards InvalidOperationException, but I'm not entirely certain that's the best choice.


What is the last mission I can do for each faction before they'd hate me?

As you reach the end, you get 3 missions, each indicating that one of the 3 main factions (the NCR, Caesar's Legion and Mr. House) are watching you and if you continue to help the other 2 factions you'll be treated as an enemy and fail any remaining missions with those factions.  I am wondering, what is the last mission I can do for each of the main factions before they hate me? This would be under the assumption that I've done NCR and Legion side quests before triggering the Reputation Reset with them after I made contact with Mr. House.


prompt not appearing after running `perl`

I have asked a similar question  but it eventually evolved into a series of comments. So once again, what package should I install to see the following prompt > after running perl but now not raku (all under Cygwin)?  EDIT -l doesn't work either.  EDIT 2 Perl -d -e1 doesn't work for me either (Answer in comments as this question is closed):


Is there any way to tell if people have opened a Google Drive document that you have shared?

I sent out links (read-only) to a number of people and am curious if there is a way to see whether people are actually going out and viewing that document.   I understand it likely won't have names for everyone/anyone that looks at it, but I'd be interested at least in knowing how many "hits" it got to make sure that at least some of those I sent it too actually looked at it.


How do I delete my account and associated posts on a specific site?

I want to delete my account; can anyone help me to delete  my account?  The reason I want to do this is because Stack Overflow reduced my reputation by 500 points in a single day. Now I don't want to participate on this site anymore. So please help me to delete all of my questions and answers.


In acute angle triangle, prove that $\cos (A-B) \cos (B-C) \cos (C-A)\ge 8\cos A \cos B \cos C$

In acute angle triangle, prove that    $$\cos (A-B) \cos (B-C) \cos (C-A)\ge 8\cos A \cos B \cos C$$   My progress:  $$\cos(A-B)=2\cos A\cos B+\cos C\ge 2\sqrt{2\cos A\cos B\cos C}$$  $$\implies \prod\cos(A-B)\ge 8\left (2\prod \cos A\right )^{\frac 32}$$


Chaining up 5v LED strips using 5v cellphone chargers

I want to chain up a very long LED strip to a single source of data. I will be using an ESP8266 and about 15 meters of WS2812b LEDs. With about 30 LEDs per meter, I need to power about 450 of these total. I've read multiple places they're about 60 mAh each, so 60 * 450 = 27A required to run all of these, assuming I want full brightness at red or white (not sure which draws most).   I've experienced that I can (but should not) power about 6 meters (180 LEDs) with a single 2.1A supply, which actually ended up drawing 2.3A (Samsung phone charger). I wrapped the 6 meters around a tube, so I could easily solder some wires from the top to the bottom, so the voltage drop was lower. Every color looked great, but white had a yellow look to them. I know that wasn't suitable at all, but I was simply trying it out.  I'm now trying a different approach, which should work much better. If I for every 3 or 4 meters wire up a wall charger to the strip, can I achieve what I want? This is what I had in mind:    Here's another thing I had in mind, which would help a lot, since I don't have wall outlets every x meters in my house. Can I do something like this instead, if I make sure to use good gauge wires, so they don't lose voltage?:    As a third option, I have a couple of 12v 2A supplies (like the ones above). Can I buy some cheap, alternative hardware, such as voltage regulators, and wire it up in an alternative way?  The question here is not powering the strips. The question is really if chaining the supplies as my first image is possible and what might could go wrong, if I do it that way.


"I hold doors open just to see people do that little run" - do vs doing

What would be the correct form and why? Both could be used, but I think the do version is colloquial. I am interested in the reason though I hold doors open just to see people do that little run or I hold doors open just to see people doing that little run?


Does Mercy's damage buff affect structures?

Mercy's Caduceus staff has an alt-fire that increases an ally's damage while channeled.  Does this damage buff also extend to structures, such as Torbjörn's turrets or Symmetra's sentries, if their owner is currently receiving the buff? If so, is it global -- that is, is there a maximum range the structures can be from Mercy or her target to receive the buff?


I want to make an attendance sheet in excel. If a child is present, the teacher will write P in a cell, or A for absent, or L for latecomer. I want to get the number of P or L in a range to calculate total number of days in a month for each child, where the child has been either present or late.  How can I accomplish this?


I've searched for a similar question and haven't found one yet, so here goes:  How do I roll back to a previous installation of WINE without knowing what that version was?  Backstory:  I played a game on my Ubuntu machine using WINE a few months ago and noticed that an error kept occurring under certain circumstances that made it almost unplayable.I stopped playing.  Fast forward a few months and a few WINE updates and I decide to give the game another go. To my delight, the error has stopped occurring. Then, I notice a new WINE update and decide to install it.   Using these commands:  wget -nc https://dl.winehq.org/wine-builds/Release.key sudo apt-key add Release.key sudo apt-add-repository https://dl.winehq.org/wine-builds/ubuntu/ sudo apt-get update sudo apt-get install --install-recommends winehq-stable   Now the game is performing the same error and it has become unplayable again.   So, my question is:  Without knowing what that last version of WINE was, how do I get back to it? This game is in early alpha and has not been released yet. It's also a very 'niche' sort of game, so there wont be a large amount of people playing it, and even fewer on Linux (I'm the only one I know of). I can't expect any help from other players. They're all on either Windows or Mac.


I unwrapped a simple plane and applied the following 80x80 pixel picture:    Yes, it's quite small. The problem is, the result is all blurry, like so:    How do I make it accurate to the pixel?


Android Google Maps getMapAsync() gives NullPointer (tried other suggestions)

I want to implement a map on a fragment. But when I call getMapAsync() it gives a NullpointerException:  java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.SupportMapFragment.getMapAsync(com.google.android.gms.maps.OnMapReadyCallback)' on a null object reference                                                                             at kontrolleur.radar.de.radar.fragment.MapFragment.inOnCreateView(MapFragment.java:33)   MapFragment.class:  public class MapFragment extends BaseFragment implements OnMapReadyCallback {  public static MapFragment create(){     return new MapFragment(); }  @Override public int getLayoutResId() {     return R.layout.fragment_map; }  @Override public void inOnCreateView(View root, @Nullable ViewGroup container, Bundle savedInstanceState) {     SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map_container);     mapFragment.getMapAsync(this); }  private GoogleMap googleMap;  @Override public void onMapReady(GoogleMap googleMap) {     this.googleMap = googleMap; } }   The fragment lays within a ViewPager btw.  Here's the fragment_map.xml:  <?xml version="1.0" encoding="utf-8"?> <RelativeLayout  xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent">  <com.google.android.gms.maps.MapView     android:id="@+id/map_container"     android:layout_width="match_parent"     android:layout_height="match_parent"     />     My Manifest File:  <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="kontrolleur.radar.de.radar">  <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />  <application     android:allowBackup="true"     android:icon="@mipmap/ic_launcher"     android:label="@string/app_name"     android:roundIcon="@mipmap/ic_launcher_round"     android:supportsRtl="true"     android:theme="@style/AppTheme">     <meta-data         android:name="com.google.android.geo.API_KEY"         android:value="@string/google_maps_key" />     <meta-data android:name="com.google.android.maps.v2.API_KEY"         android:value="@string/google_maps_key" />     <meta-data         android:name="com.google.android.gms.version"         android:value="@integer/google_play_services_version" />     <activity android:name=".MainActivity"         android:theme="@style/FullScreenTheme">         <intent-filter>             <action android:name="android.intent.action.MAIN" />              <category android:name="android.intent.category.LAUNCHER" />         </intent-filter>     </activity> </application>     The api key lays within the google_maps_api.xml and is valid.  What I tried:  First I replaced the mapFragment with a new Instance of SupportMapFragment. But this didnt work and put a blank screen on the fragment.  Then I tried to put the mapFragment.getMapAsync(this); into different methods (like onCreate, onViewCreated etc.). Still a nullpointerexception.  I also replaced getChildFragmentManager() with getActivity().getFragmentManager().  Am I missing something?  My MainActivity extends AppCompatActivity and BaseFragment extends Fragment if that is a help.


How could I run this command as an alias? alias findsum='find /home/sams/ -name sum.txt -exec grep -H "$1" {} \;'  This should be very simple, but I am not able to make it work. findsum test find: paths must precede expression: `test'


Unable to set selected attribute of dropdown using Jquery 3.4.1, c# mvc

I am trying to set default value in dropdown when HTML page is loaded. I have filled the dropdown values dynamically from code as 0 = Select, 1 = Required and 2 = Not Required  I have written below line of code to set the value as "Required".  $("#ddltest option:contains('Required')").attr('selected', 'selected');   However the "Not Required" option is getting set.  C# fiddler link below:


How to match first occurrence of a string with Regex?

My regular expression matches the string in the last occurrence of VALUE. How do I tweak my RegEx to match the string only in the first occurrence after a certain string?  Regex: NAME="var1".+VALUE="(.+)" Text:  <INPUT TYPE="HIDDEN" NAME="var1" VALUE="value that i want to be captured"/><INPUT TYPE="HIDDEN" NAME="var2" VALUE="value2"/><INPUT TYPE="SUBMIT" VALUE="value that is captured, but i don't want to be captured" />   My current RegEx captures the value: "value that is captured, but i don't want to be captured"


Why doesn't `sudo su -l -c "java"` work even though `sudo su -l -c "echo $PATH"` displays the location of the java binary?

I have a server with Java binaries from a tarball on a custom location, and the following in /etc/bash.bashrc:  export JAVA_HOME=/path/to/java/home export PATH=$JAVA_HOME/bin:$PATH   When I run sudo su -l -c "java", I get -su: java: command not found. However, when I sudo su -l in directly, I can run java without errors.  Furthermore, sudo su -l -c "echo $PATH includes the location of java.  Why does sudo su -l -c "java" fail to run?  EDIT: Even though it is /etc/bash.bashrc and not ~/.bashrc, the same reasoning applies in the linked question/answer.


What practical options does Ubuntu have to make daily personal backups?

To protect my personal data against sudden hard drive failure, I basically began mirroring my internal drives to an external hard drive a while ago. I do this regularly with all of my data partitions, since I am unable to cleanly separate my most important data from other things, which may not be essential, but possibly not easy to replace.  Since the space on both drives is still sufficient, I see the benefit in simply copying all data, so that even a complete system failure would leave me with my newest files and system structure still intact on my external drive, which I find very reassuring.  The problem with this method is that:   I can't be sure that the mirrored data is identical to the original files (except if I would do a checksum comparison on all files, which I only would know how to do manually at the moment and which would take a lot of time). Tools to mirror two partitions usually look for changes in the editing date of two files to identify what data must be copied, but are unable to tell if a file has canged on either side because of drive failure in some sectors and may have become corrupted or unreadable.   I would like to keep the ability to make a daily backup within some minutes and without imaging/copying my whole partition every time, but increase the security of my data with a different method than "simply copying" the files.  Is there any program or workflow available on Ubuntu that lets me keep my backup habits and addresses the issues I outlined above?


Did merging Black Holes in GW150914 give up entropy and information to the gravitational waves, since they lost 3 solar masses?

Since the final Black Hole (BH) had 3 solar masses less of mass than the original binary BH, it seems the 2 BHs lost mass, and with it event surface area, entropy, and information. If that came from inside the BHs it seems that it would be a contradiction of what a BH is --'nothing escapes its event horizon'. Some may say that came from the rotational energy of the pair, but the new BH now seems to have less than the two original ones summed. So, did some of that escape the horizons?


Command line MP3 and OGG tagger with picture support (cover fetcher)

I am searching a command-line tagging tool that supports ogg- and mp3-tagging and allows to add a picture to the tags.  Currently I use  but that does not support pictures.  is the tool I use before but it is lacking picture support as well.


Python: Creating a new list out of a range of indices from another list

I have a list: A = [6, 4, 3, 5, 2, 1] and I want to create a new list: B = [] where B is populated by the elements from A in range of indices 0 ---> 0 + some variable.   (that is, given a range of indices in A, how can I copy the elements over that range into a new list B?)


Where did Schrödinger solve the radiating problem of Bohr's model?

One of the problems with Bohr's theory to describe the hydrogen atom, was that the electron orbiting around the nucleus has an acceleration. Therefore it radiates and loses energy, until it would collapse with the nucleus.  Now Schrödinger describes the electron as a wave function. His theory is able to describe all atoms (in contrast to Bohr's model), but how is the radiation problem solved? I understand that the wave has not an exact position in the time anymore. But the electron still "moves", so it has an acceleration anyway (because of vibrations or so).   Why is in this theory the electron not radiating anymore? And if it is, why doesn't the atom collapse?


When would you call java's thread.run() instead of thread.start()?

When would you call Java's thread.run() instead of thread.start()?


Let $X$ be a noetherian space. We say a subset $Z$ of $X$ is constructible in $X$, if it is a finite union of locally closed subsets of $X$.  There is the following theorem of Chevalley(we are not supposed to prove it in this thread).  Theorem of Chevalley Let $X$ be a scheme. Let $Y$ be a noetherian scheme. Let $f\colon X \rightarrow Y$ be a morphism of finite type. Then $f(Z)$ is constructible in $Y$ for every constructible subset $Z$ of $X$.  Hartshorne Exercise II. 3.19 (a) is as follows. Show that the above thorem can be reduced to the following proposition.  Let $X, Y$ be affine and integral noetherian schemes. Let $f\colon X \rightarrow Y$ be a dominant morphism of finite type. Then $f(X)$ is constructible in $Y$.  How do we show this?


Consultation Linux command "chmod'. Why this command no work?

I have a faulty equipment with OS Linux. I found a spare part, but I need change the it serial number through Linux. I'm trying to change it using the command chmod. But it no working. Information about serial number is available here: cd /proc/board_info/ ls -l -r--r--r--    1 root     root            0 Jan  1 00:03 serial_number Change access for /proc - OK  Before cd /proc  ls -l dr-xr-xr-x    2 root     root            0 Jan  1 00:03 board_info  After  chmod 777 /proc ls -l drwxrwxrwx   31 root     root            0 Jan  1 00:00 proc Change access for /proc/board_info - Negative  Before  cd /proc ls -l dr-xr-xr-x    2 root     root            0 Jan  1 00:03 board_info  After chmod 777 board_info/  ls -l dr-xr-xr-x    2 root     root            0 Jan  1 01:29 board_info OR chmod 777 -R /proc/board_info/ cd /proc ls -l dr-xr-xr-x    2 root     root            0 Jan  1 01:28 board_info


CSS Vertically & Horizontally Center Div

I have a pop up which contains an ASP.NET form, click the link "Request Information" and the form appears.  However, the pages that have the link "Request Information" to trigger the pop up have a lot of content therefore scrolling is required to see the link.   I need to have the div always centered if a user scrolls to read the content, otherwise if they don't scroll the pop up still appears centered on screen.  The div is positioned absolutely, the whole page width is 960px with margin set to 0 auto.


What does "like someone for someone" mean?

I have come across it in the 9th episode of the 10th season of Friends. Here is the contex:  Chandler: Monica, I want a baby too, but this woman is giving away her child. She deserves to know who it's going to. Monica: (realizes Chandler is right. She's almost crying) okay, right. (They hug) Chandler: So, we'll tell the truth and who knows, maybe she'll like us for us.  I think it means to like someone for what they are, but it's the first time I have seen the phrase. If it means exactly the same as like some for what they are, would it sound as natural if Chandler said maybe she'll like us for what we are? If not, what are other ways to paraphrase it?


Can I use a different voltage / amp to what the device is rated?

Please bear with me as my knowledge on electrical is very limited.  Background   Question relates to a driving simulator product = Thrustmaster T500 Product uses a 24v / 6.67a 4 pin power supply (factory supplied)   Context   I intend to purchase one but it does not come with a power supply I can source one on Amazon / Ebay but it is extremely expensive ($100AUD) The product will be used in Australia. There is someone who has used a 19v / 7.1a laptop power supply and simply cut the wires (male from power unit / femal in the base) and connected the positive and negatives back together in order to power the unit. They claim everything works, and been using it for over a year with no problems   Concerns   I understand if I do this I will lose any warranty on the base Unsure if not using recommended volt/amp is a wise decision Asthetically it will look ugly as its hard to hide all the wires The only Pro is that the cost will be very minimal, especially if I can find a 2nd hand laptop PSU   Question   Is doing it the "cheap" way possible and logical ? What are the implications of using the non recommended volt/amp   BTW - I tried to find an answer to no avail. Thanks heaps for reading up this far and your feedback will be greatly appreciated :)  Kind regards  Gary


Is there a simple yet accurate formula for where on Earth the Sun and Moon are directly overhead?

I'm trying to improve  that shows the region of the Earth currently under daylight, and I  need a formula that, given the current time, tells where  (latitude/longitude) the sun and moon are overhead, accurate to 1  mile. Can anyone come up with one?  Ideally I'm hoping to get something JavaScript can calculate at a "reasonable  speed" without recursion, loops, or extra libraries.   I've tried several things (eg, Fourier series on the Sun/Moon's  RA/DEC), but nothing seems quite accurate enough.   Note: I realize my calculations for sun/moon rise/set ignore  refraction and lunar parallax: for now, I'm focusing on finding the  overhead positions. I realize I can pull data from a non-JavaScript CGI program (and have tried that), but it seems like a lot of unnecessary network access.  EDIT: Thanks, Dustin and everyone.   Actually, I'm aware of  and even  wrote programs to download and parse their data  (  and  )  with the hope of finding simple formulas  (  and others), but got nowhere.   I realize I could hardcode the data into my JavaScript but that would  make the script unnecessarily large.   Currently, I rebuild the script every minute  ()  using interpolated JPLs data (the sun/moonfakex/y.txt files in  ), but this  seems insanely complicated.   This may be an inherently difficult and/or pointless question: to get  accuracy of 1 mile, you have to calculate the position within 52  seconds of arc, which is considerably smaller than the 30 minute (1800  seconds) width of the sun and moon themselves.   The ultimate goal is to let people zoom into their city on google maps  and watch the sunset "sweep" over their city (ie, predict the sun is  setting over a certain part of the city and have people in that part  of the city confirm it), but given refraction and parallax, this may  be impossible.


It seems like Hibernate function is not working properly on Ubuntu 18.04. I have tried with several commands like sudo pm-hibernate, and sudo systemctl hibernate etc. Nothing works.  Is hibernate also related to Hardware? My laptop RAM is 16GB and I have created the swap partition with the size of 24GB.  Any suggestion?


C++ - double type alternative for subtraction of decimals?

I'm writing a function which accepts a double data type, say variable 't', and if 't' is equal to 0.05, the function does something.  Now, my problem is that if 't' is 100-99.5, the function fails to work. But it works for 't' = 0.05-0. I'm guessing this is something to do with how numbers are stored. What's the work around?  PS : I'm not a programmer, merely using C++ as a tool, so I don't know much about it other than the basics. A simple solution would be very appreciated.


Im having a null pointer exception error in below code.   Exception in thread "main" java.lang.NullPointerException at BookTest.createInstances(BookTest.java:53) at BookTest.main(BookTest.java:20)   i could really use some help, ive been stuck on this for quite a long time.   import java.io.*; import java.io.FileNotFoundException; import java.io.FileWriter; import java.io.IOException; import java.util.ArrayList; import java.util.Formatter; import java.util.Scanner;  import javax.swing.JOptionPane;  public class BookTest {   public static void main (String[] args){  ArrayList list = createInstances(); writeFile(list);  }   public  static ArrayList<Book> createInstances() { ArrayList<Book> bookArray = new ArrayList<Book>(); String inputArray[] = new String [10]; int i = 0; Scanner input;     // Read the text file and stores into inputArray where each line is stored as String. try  {     input = new Scanner( new File("book.txt"));     input.useDelimiter("\n");     while (input.hasNext()){         inputArray[i]=input.next();         i++;     }          // dataArray defines the two dimensional array that store all the values in the line.     String dataArray [] [] = new String [10] [11];       System.out.println(inputArray.length);     for (int k =0; k<inputArray.length; k++){          String getLine = inputArray[k];         String[] eachLine =getLine.split(" ");         int length = eachLine.length;             for ( int j=0; j<length;j++){              dataArray [k][j]= eachLine[j];          }     }        for (int l = 0; l < 10; l++)         {             if (dataArray[l][0].equals("Fiction"))             {                 Publisher p = new Publisher(dataArray[l][3], dataArray[l][4]);                 bookArray.add(new Fiction(dataArray[l][1], dataArray[l][2], dataArray[l][5],                 p, Double.parseDouble(dataArray[l][6]), dataArray[l][7], l));             }              else              {                 Publisher p = new Publisher(dataArray[l][3], dataArray[l][4]);                 bookArray.add(new NonFiction(dataArray[l][1], dataArray[l][2],dataArray[l][5],                 p, Double.parseDouble(dataArray[l][6]), dataArray[l][7], l));             }         }  }   catch (FileNotFoundException e) {      e.printStackTrace(); } return bookArray; }   public static void writeFile(ArrayList arrayOfBook)  { Formatter output ;   try   {      output = new Formatter("book.txt");             for(int i = 0; i<11;i++)             {                 output.format( "%s %s %s %s %s %s %s %s %s %s %s \n", arrayOfBook.get(i));             }     }         catch (IOException e)    {         // TODO Auto-generated catch block         e.printStackTrace();         }       }   }   this is the file im trying to read   Fiction AbrahamLincolnVampireHunter Grahame-Smith Wiley NY 978-0446563079 13.99 222 true 12 1/1/2015   Fiction Frankenstein Shelley Prescott GA 978-0486282114 7.99 321 true 8 5/12/2008  NonFiction LifeofKennedy Jones Pearson MT 758-29304566 12.90 biography 3 11/11/2011


The question In my native language we have two ways of saying the food is hot. One meaning spicy and one meaning too/very warm.  I am now looking for a way to use this sentence:     The food is ...{single word here}...   I want the meaning to be clear (the food is warm to the point where caution is recommended). If there is not a single word for this that is also fine, I could then at least start looking for better workarounds.  Thoughts so far I always used 'hot' but that can easily be confused with spicy so I am currently using workarounds.  'Warm' can mean 'nice and warm' or 'too warm', so I am not satisfied by that either.


How do you export a rendered 2D animation?

I've been attempting to render my 2D animation by selecting "render", "render animation", but I can't see where to proceed from there.  Is there a way for me to save the render or export the animation as a video file rather than a .blend file?


What is the relation between image file size and image quality?

Is small image file size means low image quality?what is JPEG image file size of 5d mark iv .Can we achive better image in small image file size?


With seemingly increasing frequency I come across a phrase using 'learn' when I think it should be 'teach'.  The classic example is 'that will learn them!', as in "Shoot all criminals - that will learn them!". I thought this was being deliberately wrong for comedic effect, in keeping with the general sentiment of the sentence.  Another example from a Stack Exchange site (http://programmers.stackexchange.com/questions/53880/stuff-you-should-have-learned-in-school-but-didnt-pay-attention-to-at-the-time)     I don't know if you can learn someone   to write at this age   Am I being overly fussy/old fashioned or is this just wrong?


How did Rømer measure the speed of light by observing Jupiter's moons, centuries ago?

I am interested in the practical method and I like to discover if it is cheap enough to be done as an experiment in a high school.


Re-projecting shapefile from an unknown projection

I have been given a shapefile which is supposedly in a NAD1927_Zone16 projection. I need to align it with a raster image in a Lambert Conformal Conic (NAD 1927) projection.  I've tried to use the Project and Define Projection tools to verify that this shapefile is in NAD1927_Zone16, but when I compare to other data it is no where near where it should be (leading me to believe that the projection indicated on the shapefile is not correct).   In addition, I've edited the Standard Paralell and Latitude of Origin and Central Meridian values as per:    And I've also tried loading in a custom projection from a .prj file downloaded from the following site:   I haven't done much with projections or transformations before, but I really didn't expect it to be this complicated when I agreed to the task.


Is there any Linux based compiler which supports graphics.h library? I want to implement graphic programs, so please kindly let me know if there is any such software.    If not then how  can I use it?


The question is is the interior of closure of an open set equal the interior of the set?  That is, is this true:  $(\overline{E})^\circ=E^\circ$  ($E$ open)  Thanks.


If the range of $f(x)= \frac{x^2+x+c}{x^2+2x+c}, x\in \mathbb R$ is $\left[\frac 56, \frac 32\right]$ then what is $c$?

If the range of the function $f(x)= \dfrac{x^2+x+c}{x^2+2x+c}, x\in \mathbb R$ is $\left[\dfrac 56, \dfrac 32\right]$ then $c$ is equal to?    Attempt:   $y=  \dfrac{x^2+x+c}{x^2+2x+c}$  For real values of $x$, $\Delta \ge 0$  $\implies 4y^2(1-4c) +1-4y(1-2c) - 4c \ge 0$  What do I do next? I am really unable to understand the concept to be followed after this. Could someone explain that?   The answer is:       $c= 4$


An installation of owncloud requires 12.04 server but mine is not stated as"server"

I am a super newbie so I hope this is not a stupid question but what will I need to qualify to run this software package? I've installed openssh and apache2 and they work fine so I think many of the server attributes may be on my system but how might my system yet be lacking?


(1) I want to work in a small company.  (2) I want to work at a small company.  (3) I want to work for a small company.  (4) I want to work with a small company.  What are the connotations given by these prepositions?


regexp in ksh for extensions tgz, tar.tgz

I'm trying to get a regexp (in ksh) to identify files with only the following extensions: tgz, tar.gz, TGZ and TAR.GZ. I tried several but can't get them to work. I'm using this regexp to select only files files with those extensions to do some work with them:  if [ -f $myregexp ]; then    .....  fi


Does the Flaming Sphere spell come with or as a bonus action as a default?

Reading PHB p. 242 about  (second paragraph) it begins “As a bonus action, you can...”.  Does this mean that when it is cast that a wizard gets to use a bonus action and move the sphere?  And if so, does this mean that on each of this wizard’s turns (within 1 minute duration), he gets to use a bonus action to move the sphere?  Or  Does a wizard have to have a bonus action (in his back pocket so to speak) to make use of this feature of the spell (being able to move it).


Why was my answer, linking to my Google Code project, deleted?

My answer to a question was recently deleted by Andrew Barber (20K+ member) and I am wondering why. It fundamentally answers the question (although it wasn't the accepted answer) and was also up-voted twice.   is the question.   is the answer in question.


Is every group the commutator subgroup of some other group?

This is a result I haven't been able to find. An answer for finite groups or general groups would be great. A simple proof would be appreciated if possible.


By mistake I have installed 64-bit linux(hey! it happens to every1!). How can I run 32-bit  app under that linux?


How do I remove top panel on dual screen on secondary monitor?

How do I remove top bar on secondary monitor??


What is the cardinality of a transcendence basis of $\mathbb{C}$ over $\mathbb{Q}$? Is it that of the continuum? Proof?


Mounting FreeBSD formatted HDD (ufs) in Ubuntu?

New here(and to Linux), hope someone can help me. I'm trying to mount two HDDs that come from a FreeBSD box (mainboard died) on my freshly installed Ubuntu (16.04). I get the following error...  tv@Media-Centre:~$ sudo mount -r -t ufs -o ufstype=ufs2 /dev/sdb /home/tv/ufs_mount mount: wrong fs type, bad option, bad superblock on /dev/sdb, missing codepage or helper program, or other error  In some cases useful info is found in syslog - try dmesg | tail or so.   Any pointers please?


Does $30$ always divide $n^5-n$ where $n \in \mathbb{Z^+}$?

Does $30$ always divide  $n^5-n$ where $n \in \mathbb{Z^+}$ ?


How to access the second argument from the last command in the history ?

I am starting to learn some Regex, therefore I use this command repeatedly:  grep pattern /usr/share/dict/american-english    Only the part with pattern changes, so I have to write the long expression "/usr/share/dict/american-english" again and again.   Someone made the remark that it is possible to expand an argument of a command from the command history by typing cryptic character combinations instead of the full expression.  Could you tell me those cryptic character combinations ?


Why are the costumes in comics and movie adaptations not the same?

For example, take the Wolverine character.  Wolverine in comics look like this:    Whereas in movies he looks like this:    Why are the costumes not the same in the comics and their movie adaptations?


Galaxy S not detected, how do I make it work?

Can anyone please provide the necessary steps to connect a Samsung Galaxy S with Ubuntu 10.10 please? I was thinking that perhaps it could detect something, but it doesn't, Anyone succeeded ?   Thanks


Can I have multiple Schengen visas for future travels in my passport?

I'm a citizen of Ukraine planning on visiting Italy early in October for tourism. Later that month I'm accepted as a speaker at the conference in Prague, Czech Republic. Both countries are members of Schengen agreement and a visa is required for me to visit them. Therefore, I need to visit Schengen countries 2 times and I need to get my visas ASAP (to confirm my talk to the conference organizers, as well as to avoid overpaying for hotels/flight tickets).   I've heard a number of times that a single person can't apply for a Schengen visa if already in possession of one, but I'd like to clarify this. Say, I've got a visa from Italy for the period of October 1st - October 14th. Can I get another one from Czech Republic for October 25th - October 30th before I visit Italy? Would the answer be different if I were to visit the second country (CZ) on October 13th - October 20th, thus, having a single day overlap between these visits. It would be of a tremendous help if you could link to the official documents that prove your point, but I'd certainly appreciate answers even without such links.  Both times I'm going to apply for a short-term tourist visa covering the dates of my travel. If the answer to both questions above is no - would several visits to multiple Schengen countries over a short period of time be a valid reason to apply for a single multiple-entry visa that covers the whole period from October 1st to October 30th from Italy?


Show by induction : $n^7-n$ is a multiple of 7

I have to prove this : "$n^7-n$ is a multiple of 7". This is what I have done this so far :  $P(n):n^7-n$ On putting $n=1,$ $P(1):1^7-1=0$, which is a multiple of 7. So, $P(1)$ is true. Let $P(k)$ be a multiple of 7. So, $k^7-k$ is a multiple of 7. So, $k^7-k=7m$, where $m$ is any natural number. Let $P(k+1)$ be true, Hence, $(k+1)^7-(k+1)$ is a multiple of 7.  Now, how do I evaluate $(k+1)^7$ without using the binomial theorem ? Or is there some other way to do it ?


Mathematical Induction question talking about words

This is the question:   I am still struggling with this and here is my answer so far:    I found some difficulties to get the a3. Can you check my implementation? then, how do I actually get the expression for my finding?


Increasing effort for "Visiting the site each day"... Participation Badges?

I am presently 30 days away from earning the gold ; however, in retrospect, I feel that this badge, and the silver , when compared to other silver and gold badges, are far too easy to attain.  In my opinion, the difficulty of the Enthusiast badge should make it a bronze badge, not silver, and the Fanatic badge a silver, not gold. My perspective is that a gold badge should be something that takes a considerable amount of dedication, effort, and/or hard work to attain, just like all of the other gold badges.    If you look at our present numbers, there are over 64,000 people that have earned the Enthusiast badge, and well over 10,000 that have earned the gold Fanatic badge.  And when you compare these numbers to many of the other silver and gold badge, the numbers just don't line up.  I'm not expecting a 1:1 relationship here, but I am expecting to see a similar pattern of a low percentage of people earning the gold badge; however, in this case, there are many more people earning the gold Fanatic badge, than there are people earning many of the silver badges! It's just way to skewed IMO.  So, I have the following suggestions to remedy this:   Enthusiast badge: Change from Silver to Bronze, keeping the existing requirement, "Visited the site each day for 30 consecutive days." Fanatic badge: Change from Gold to Silver, keeping the existing requirement, "Visited the site each day for 100 consecutive days." Add a new gold badge:     Possible names: A. "Devoted" B. "Dedicated" C. "Habitual" D. "Zealous"   Eligibility: "Visited the site each day for 365 consecutive days."    I feel that this change will put these new bronze, silver, and gold badges in alignment with many of the other badges in regards to difficulty and/or amount of effort.


How to delete attachments/images from an email without deleting the email itself (Gmail)?

I've received a bunch of emails with large attachments and images.  I want to keep the emails (including their headers) for my records, but I don't want the attachments and images using up my allotment of storage on Google's servers.  I also want to keep my backups small, and they add unneeded bulk to my backup files. In Gmail, how can one delete attachments/images from emails without deleting the email itself? To keep this QA generic enough to help everyone, answers addressing sent and/or received emails are fine.


Times New Roman font installation problem in ubuntu 16.04

I have installed times new roman font through terminal ubuntu 16.04, at the last moment terminal got struck. Now I cant reinstall times new roman font. I ran few commands with following result:  $ sudo apt update   .   . update done $ sudo apt-get install ttf-mscorefonts-installer E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it? $ sudo apt-get remove --purge ttf-mscorefonts-installer E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?


I am a casual TeX user. Mostly I have used it to type up some reports/homeworks for class in my graduate engineering work. In the past I have used document type "article". And then kept all the defaults.  I need to self publish something online. At the highest level I would like to know: How do you setup a TeX document to self publish a book online?  Some more low level questions:   Is there a document type for "book" and what is its name? I am looking at Amazon Createspace. : filetype=pdf, trim size, margins (gutter and outside margins). All of these various trim size, margins gutter/outside can be adjusted in the Tex document?   Has anyone seen any good TeX templates for Amazon Createspace? If you could demonstrate how to tweak a specific "book" document type that would be very helpful also.    Other than the above questions, please feel free to offer any other sort of help since I am completely new to this process (advice, links to good tutorials, links to wikibooks).


Where does this matrix rotation formula come from?

Im in a book and they use this rotation matrix formula in the picture.    Where does it come from. I know that the c in the matrix is for Cos and the s is for Sin.  Is there a proof?


Let questions stay open for a minimum amount of time before being closed

Feature Request  *****Make questions unclosable until one hour after they've been asked, with an exception for flagged questions.*****  Question  What reason can you give for a non-abusive but otherwise bad question being closed as soon as possible?  Bonus points for explaining the rationale behind your answer.  Rebuttal  Since closed questions can still show up on various lists, the implication is that deletion is the goal of closing a question.  Since a question can't be deleted for two days (), why the fuss about delaying the closing of a question for a relatively small number of minutes?  The notion that the signal-to-noise ratio on the home page outweighs all other considerations assumes that most people answer questions mainly from there.  I almost never use the home page, preferring the newest or active tabs, or using a tag.  Seeing as the number of closed questions is so low, I'd hesitate to call them "pollution." I would guess that less then 10% of any of the regular lists consists of closed questions.  Also, it seems that it is much easier to close a question than to .  If you disagree, I invite you to put your reasons in an answer or a comment before doing so with a downvote.   is not a duplicate of this because it is asking what the social norm of the community is for voting and mine is a feature request.  For those who claim that keeping a question open pollutes the home page, I would say why don't we request a feature so that questions with even 1 close vote not appear on the main page at all? This solves the so-called 'pollution' issue.  Related question


Save and close VF page Pop Up on Single Click

I am trying to save and close a VF page on clicking 'Save' command button.Here's my code  <script type="text/javascript">     function closewindow(){         window.close();         geopointe.api.closeAction();     } </script>  <apex:pageBlockButtons>     <apex:commandButton value="Save" action="{!save}" oncomplete="closewindow();"/> </apex:pageBlockButtons>   The issue here is oncomplete function is getting executed without saving the record and closing the popup.If I remove the autocomplete function then ,my code is working fine,running validations on page and then saving the record.Does anyone has an idea how can I  perform the save before closing the window? Thanks in advance!


Where did folder "merge" or "keep both" go in OS X 10.9 Mavericks?

Before Mavericks one could hold the ALT key and move a folder "A" onto a folder "B" where already an "A" existed. In this case Mac OS X asked in Lion if I want to merge - or on Mountain Lion if I want to keep both (which was also a merge).  I can't find this option in Mavericks.  Did Apple remove this useful feature?  Any hints?  (And yes: I own ForkLift, which can do it - I just sometimes still prefer the Finder).


Root directory only showing about half of total available drive space

I am running Ubuntu 18.04 server edition on an Intel NUC7CJYH, and noticed I only had about 50% of my SSD available. Running sudo lsblk showed the following: NAME                      MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT sda                         8:0    0 465.8G  0 disk ├─sda1                      8:1    0   512M  0 part /boot/efi ├─sda2                      8:2    0     1G  0 part /boot └─sda3                      8:3    0 464.3G  0 part   └─ubuntu--vg-ubuntu--lv 253:0    0   200G  0 lvm  /  How can I resize the partition under sda3 to make use of the entire drive? I found , but it is quite a bit more complex than what I am working with, and I'm not quite sure what to google to get to the root of my issue. I appreciate any help!


UID/GID mapping for external storage across different POSIX systems

I have access to multiple POSIX desktops where my personal user account has different UID/GID.  I use an ext4 formatted portable SSD, which is great for my work, except for the permissioning issues arising from having different UID/GID on the different desktops.  I understand the design trade-offs of UID/GID permissioning, and synchronizing UID/GID across those desktops is not an option.  Is there a better solution than starting my work session on each desktop with:   sudo chown -R `id -un`:`id -gn` /media/$USER/disk   that   does not require root priviliege; does not unnecessarily write metadata (and wear the SSD); does not require the creation/management of additional groups or other UID/GID manipulations on any of the concerned desktops; does not require setting specific permission to individual files; and does not add (unnecessary) complexity?


Ethernet cable connections from coaxial cables

I have two unused coax cables in my the garage. Considering that Ethernet uses only 4 conductors, can I use these two coax cables as my 4 conductors? I could wire the ends to Cat 5 connectors.


How does polaroid filter work at the atomic level?

I know it works by blocking electric or magnetic component of wave while allowing other but what happens at the atomic level , do the atoms absorb the electric component e.g by excitation of electrons ? or do the bonds resonate at frequency of electric component of wave ?


multiple citation with specific pages biblatex-apa

I'm using biblatex-apa and trying to get a multiple citation wit specific pages  What i want to get:     (Author1,p.1; Author2,p.2)   my (working) workaround right now is this:  (\cite[][1]{author1}; \cite[][2]{author2})   but the problem here is the missing sortcites option   is there a way to do this with \parencite ?  when I'm trying to use \cite described like  does not work; my code:  \cite[][1]{author1}[][2]{author2}   neither does \parencite work  \parencite[][1]{author1}[][2]{author2}


Problem with TikZ commutative diagrams: No shape named tikz@f@1-2-2 is known

I am using the Cambridge thesis class file that can be openly found    In specific I want to use a commutative diagram with tikz-cd but I cannot make it work:   \[ \begin{tikzcd}   A \arrow[rd] \arrow[r] & B \\   \end{tikzcd} \]   Is there any way to fix this? The error reads   ! Package pgf Error: No shape named tikz@f@1-2-2 is known.


Why would a company care about the price of its own shares in the stock market?

After a company has issued shares, why should it care if the value of the shares fluctuate? Since the shares are now publicly traded, if the value fluctuates, that is strictly a transaction between buyer and seller, none of whom are directly related to the company. E.g. if I sell X an iPhone for $100, why should I care if X is selling the iPhone to Y for 1 dollar or 1000 dollars? I have got my $100, so I need not bother. No?


I am displaying the date and time in Android with this format: 2015-11-25 23:25:00  How can I change it to the following format? 2015-11-25  I wrote some code ,but not working correctly.      public static Date toDate(boolean isCurrentDate, String dateString) {     Date date=null;     DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");     try {         if (isCurrentDate)             date = new Date();         else             date = formatter.parse(dateString);         System.err.println("Printresult" + formatter.parse(formatter.format(date)));      } catch (ParseException e1) {         e1.printStackTrace();     }      System.err.println("Printresult2" + date.toString());     return date; }   I log and result is like this  Wed Nov 25 00:00:00 GMT+00:00 2015   How i can change date format  like this : ? (2015-11-25)


My Ubuntu VM keeps wanting to reinstall Ubuntu!

I've already installed ubuntu 12.04 in Virtual Machine but whenever I shut down the machine and open the Virtual Machine again it keeps asking to install it again?  Any idea how to solve this problem?


How to save php file in /opt/lampp/htdocs without going to terminal and type sudo gedit?

I am very new to Ubuntu and I still don't understand a lot of basic concepts so please bear with me.  I successfully installed XAMPP 1.7.4  in my ubuntu 11.04. The XAMPP is installed in /opt/lampp. I know how to write php file in /opt/lampp/htdocs using the bash terminal command sudo gedit /opt/lampp/htdocs/myphpfile.php but what if I already have an existing php file inside a folder? Of course I don't want to write it again using sudo command. All I want to do is copy that folder that contains the php files inside htdocs like I always do in Windows WAMP. Is there a command in which I could set the /opt folder to writeable? Please help me.


What version of Ubuntu should I install on a Samsung - Galaxy Chromebook?

I want to connect to an external hard drive. It's an easystore HDD. I'd like to run desktop-style files on it thru Ubuntu. I'm new to Ubuntu, though, and not very computer savvy, but I'm really interested in learning. Any suggestions on what I should use for operating systems on it? This is the machine I have Samsung - Galaxy 13.3" 4K Ultra HD Touch-Screen Chromebook Intel Core i5 8GB Memory 256GB SSD


How to permanently set a custom resolution?

I'm using bootable persistent USB key. I think there are some display problems, so I have to set resolution manually. These commands do it right:  sudo xrandr --newmode "1440x900_60.00"  106.50  1440 1528 1672 1904  900 903 909 934 -hsync +vsync sudo xrandr --addmode VGA1 1440x900_60.00 sudo xrandr -s 1440x900   It would be great if I wouldn't need to manually run these every time my machine starts.


Does separability imply the Lindelöf property?

Does separability imply a sort of Lindelöf property?  Since I can't prove this fact I'm beginning to think that my conjecture is false.  Intuitively, $\mathbb{R}$ has a countable subset $\mathbb{Q}$ which is used to form a countable basis for $\mathbb{R}$ with the usual topology and prove the Lindeöf property.


Serialized online story about people creating a death sport after an AI makes everyone immortal

Several years ago (4-5?), I read a story online that I believe was still being actively being published in a serial format.  The principle idea, as I recall, was that an artificial intelligence determined that it could essentially prevent people from dying altogether by suffusing everything with nanomachines (or something to that effect). The end result was that, years after the fact, a group of people made a sport of trying to kill themselves in increasingly inventive ways, with an ultimate goal of finding a loophole that allows them to die before the AI can prevent it. I think one of the main characters was the oldest woman on Earth prior to everyone becoming immortal, but that may be a different story.  I can't recall what the name of it was, and every attempt to google anything with 'AI' in the search just gives a bunch of current news articles. Thanks for the help!


Our main goal is, to keep the ability to go back SOMEWHERE but we don’t want it to be too prominent. Where should we put that button?  This is the link to the live page where this button called 'Ürün listesine geri dön'


Add time restriction in ArcGIS Network Analyst

I'm trying to use train tracks as a network in ArcGIS Network Analyst.   We are trying to create a model for security agents on board our trains and we'd like to optimize their daily "route". For now, it's all made by hand.   My approach is to take our gtfs data and create a network using stop times to determine when the train segment is "traversable". When there's a train on the segment, it's open, if not, it's restricted.   The problem is I can't set a restriction based on time in Network Analyst (or wasn't able to). I would like to be able to say by a formula or script than you can take that segment only from 7:03 AM to 7:10 AM for example.  Is it possible?  Thanks!


polar decomposition of a square A when A is not full rank/invertible

I am on the proof of the polar decomposition w/o using SVD:  Let $A$ be a real $n \times n$ matrix. Show that there exists $Q$: orthogonal, $P$: positive semi-definite symmetric matrix such that $A = QP$.   Consider the product $A^*A$, it is a self-adjoint and positive semi-definite (as we are in $\mathbb{R}$) symmetric matrix, so it has a decomposition $EDE^{-1}$ where $D$ is diagonal and $E$ is orthonormal and contains eigenvectors of $A^*A$. Now let $$   P = \sqrt{A^*A} =  E\sqrt{D}E^{-1}     $$ where $\sqrt{D}$ has diagonal elements being the squareroot of $D$. Notice that $||Px|| = ||Ax||,  $ so we can expect the product $AP^{-1}$ to be orthogonal. Provided that $P^{-1}$ exists (i.e. $P$ is positive definite), we have $||AP^{-1}x||=||x||$, so we do find our desired decomposition by letting $Q = AP^{-1}$.  The problem is that if $A$ is not invertible, then $P$ will also not invertible, regarding the whole proof useless. How should I fix it in this case?


complicated command replace in files using sed

I want to replace the below strings  replace: print 'Status Code: {code}'.format(code=r.status_code)  with: print('Status Code: {code}'.format(code=r.status_code))  Here is the command I ran which fails  find ./ -type f -exec  gsed 's/'print 'Status Code: {code}'.format(code=r.status_code)'/'print('Status Code: {code}'.format(code=r.status_code))'/g' {} \;   I tried to use \ to avoid the special characters effect but still fails too and just hangs.   find ./ -type f -exec  gsed -i 's/print \'Status Code: {code}\'.format\(code=r.status_code\)/print\(\'Status Code: {code}\'.format\(code=r.status_code\)\)/g' {} \; >  >  >


If $E=pc$ for massless particles, then it should be $p=0$ as $p=mv$ and $m=0$. Why do we use the equation $E=pc$ for massless particles?


If last two digits of $ 7^{7^{7}}=k$, find $k-38$?

I have managed to get the answer as $07$ using modular arithmetic but answer seems wrong to me because the answer after evaluation of $k-38$ is $5$.  Please help.


What is meant by __('page','twentytwelve')

I'm using twentytwelve theme with 1.0 version. I saw many codes like following,  'name' = __('page','twentytwelve');   If I give,  'name' = 'page';   It's also working fine. Then why using __()? What is use of that?


How do you set a program as a service in Linux (Debian) but have it switched off by default?

When you install Alfresco, it gives you an option of having it installed as a service or not.  If you install it as a service, the service starts up on booting but since it's using Tomcat it's too heavy to leave as a background program. In addition, it takes a lot longer to stop than Apache.  Therefore, I would like to keep it as a service but have it set to off by default so all I need to do is type sudo service alfresco start.  While I can leave it set-up not as a service and write a bash script or two, I'd like to learn more about how "services" work in Linux. Apache's not a problem but it would be nice to know where its service parameters are stored and how you can change these.


What should be the optimal parameters for Random Forest classifier?

Currently i am using RF toolbox on MATLAB for a binary classification Problem  Data Set: 50000 samples  and more than 250 features  So what should be the number of trees and randomly selected feature on each split to grow the trees? can any other parameter greatly affect the results?


How to generalize symmetry for higher-dimensional arrays?

@BrianM.Scott 's answer to this question  suggests that there is no standard concept of symmetry for 3-, 4-, N-dimensional arrays, in constrast to the case for 2-D arrays, as in linear algebra for matrices.  Are there alternative definitions of symmetry for higher-dimensional arrays?  Are there specific definitions that are widely used in certain contexts, e.g. in tensor calculus?  (I don't have a specific need; I'm trying to help implement a symmetry test for a matrix library [ for the Clojure language].  Since the library allows higher-dimensional arrays, there's a question about whether there is a natural choice for what the symmetry test should return for higher-dimensional arrays.)


How do I configure my static DNS in interfaces?

I am using Ubuntu 12.04.  My /etc/network/interfaces file consists of:    # The loopback network interface   auto lo   iface lo inet loopback     # The primary network interface   auto eth0  iface eth0 inet static   address 192.168.1.58   gateway 192.168.1.1 network 192.168.1.0   broadcast 192.168.1.255 dns-nameservers 66.212.63.228 66.212.48.10     I ran the command: /etc/init.d/networking restart  Which responded with:   *Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces   *Reconfiguring network interfaces...   RTNETLINK answers: File exists   Failed to bring up eth0   [ OK ]     Next I ran ping google.com and received:    ping: unknown host google.com   I am not sure if my interfaces refreshed. How do I properly configure my network with my static DNS addresses?


I'm trying to understand the working of RSA algorithm. I am getting confused in the decryption part. I'm assuming   $$n = pq$$ $$m = \phi(n) = (p - 1)(q - 1)$$  E is the encryption key $\gcd(\phi(n), E) = 1$  D is the decryption key, and  $DE = 1 \mod \phi(n)$  $x$ is the plain text  Encryption works as ($y = x^E \mod n$) and decryption works as ($x = y^D \mod n$)  The explanation for why the decryption works is that since $DE = 1 + k\phi(n)$,  $$y^D = x^{ED} = x^{1 + k \phi(n)} = x(x^{\phi(n)})^k = x \mod n$$  The reason why last expression works is $x^{\phi(n)} =  1 \mod n$ ? According to Eulers theorem this is true only if $x \text{ and }\phi(n)$ are coprimes. But $x$ is only restricted to be  $0 < x < n$  and $\phi(n) < n$. So $x$ should be chosen to be coprime with $\phi(n)$?  Help me clear out the confusion!


I'm new to the forest package and created a tree with a node between two nodes, that is not centered. In the picture, it's the ZS(A; C) below root. This is the code:  \documentclass{standalone} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage{forest}  \begin{document} \tikzset{>=latex}  \begin{forest} for tree={align=center} [TH(3; A; B; C), for children={l+=2ex}     [TH(2; A; C; B)          [TH(1; A; B; C)             [ZS(A; C)]         ]         [ZS(A; B)]         [TH(1; C; A; B)             [ZS(C; B)]         ]     ]      [ZS(A; C)]     [TH(2; B; A; C)         [TH(1; B; C; A)             [ZS(B; A)]         ]         [ZS(B; C)]         [TH(1; A; B; C             [ZS(A; C)]         ]     ] ] \end{forest}  \end{document}   What am I doing wrong?


I would like to package Nagios 4 on Ubuntu. Installation from source involves multiple make commands and a configure command.  wget -O nagioscore.tar.gz https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.3.4.tar.gz tar xzf nagioscore.tar.gz cd /tmp/nagioscore-nagios-4.3.4/ ./configure --with-httpd-conf=/etc/apache2/sites-enabled make all make install make install-init make install-commandmode make install-config make install-webconf    How do I make a deb or apt package out of this?   I tried following the Ubuntu instructions  When I run the bzr dh-make package version package.tar.gz, I get the following error  bzr: ERROR: Either run the command from an existing branch of upstream, or move nagioscore-nagios-4.3.4 aside and a new branch will be created there.


What is the expected number of coin tosses it takes to observe tails followed by 2 consecutive heads, given that the coin is fair?   I have calculated the expected number of coin tosses for 2 consecutive heads (=6), is there a way to use this piece of information to calculate the above question? Or is there a way to tackle this question completely from scratch?


itemize inside itemize and some of borders around the gray title section are missing

I'm interested of th Following Question   I would like to know how can I use itemize inside 'itemize' inside table I tried code of @Zarko but with no luck besides I wonder why I can't  get all 4 borders around the gray title section  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage[table]{xcolor} \usepackage{tabularx} \usepackage{enumitem}  \begin{document}     \begin{center} \setlist[itemize]{nosep,                   topsep= 0pt,                   partopsep=0pt,                   leftmargin= *,                   label=\textendash,                   before=\vspace{-0.6\baselineskip},                   after=\vspace{-\baselineskip}                   } \bfseries \begin{tabularx}{\linewidth}{ | l | X | }     \hline \multicolumn{2}{|>{\centering\arraybackslash}p{\dimexpr\linewidth-2\tabcolsep}|}{\cellcolor{gray!30}     Very long text here and centered     Very long text here and centered     Very long text here and centered}    \\     \hline \multicolumn{2}{c}{}                    \\     \hline Description &   \begin{itemize}                 \item   long text bla bla bla bla                 \item   long text bla bla bla bla                 \item   long text bla bla bla bla                 \item   long text bla bla bla bla                 \end{itemize}          \\     \hline Addition    & long text bla bla bla bla long text bla bla bla bla\\     \hline \end{tabularx}     \end{center} \end{document}


In most of Mathematics in English, the argument $x$ of a function (or partial map) $f$ with value $y$ is written $y=f(x)$ instead of, at least in Semigroup Theory and Formal Languages & Automata, $xf=y$. Why?   Thoughts:  A function $f$ is a subset of the Cartesian product of its domain $D$ and its codomain $C$ (i.e., $f\subseteq D\times C$) such that for each $d$ in $D$, $\lvert\{(d, c)\mid c\in C\}\rvert=1$. We write either $y=f(x)$ or $xf=y$ for $(x, y)\in f$.  The $xf=y$ notation has its strengths: composition of functions is usually taken left-to-right with this notation, as read in English, instead of right-to-left, with the argument $x$ first, as, I suppose, one usually has when evaluating $y$; one can read it as "$x$ through $f$ is $y$" instead of, say, "$y$ is $f$ at $x$"; and the left-to-right order respects that of going from the domain to the codomain.  Let me know if you can think of any strengths & weaknesses of the $xf=y$ notation.  I think history might have gotten the better of convention, that's all.


How can I recognize that a certain Linux distribution is based on Debian, looking at file structure?

I have an unknown (let's assume uname -a returns nothing) Linux distribution I have root access to.   How can I verify, looking at file structure, that it is based on Debian?


Multiple vs single field capture for phone number form input

Working on a form dealing with phone numbers, I've seen two methods to capture user input .   In past practices example 2 (image below) has proved effective in controlling phone number lengths on forms.   However with responsive in mind it would seem example 1 is considered a more popular pattern on forms. I've researched both patterns with the findings below.     Example 1  Pros   1 input = less taps on mobile device 1 input = less coding   Cons   could be difficult to control phone number format (1-555-555-5555, +22444455555, and etc)   Example 2  Pros   easier to control phone format reduced user error   Cons   3 inputs = more taps on mobile device more inputs = more coding   Both inputs have pros and cons and I'm not such which method would provide the best user experience for responsive environments. Can anyone share some insight or provide a better way to use phone number inputs?


I get the following error when trying to install gparted:  E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   Please help. I need to install an extra hard drive. I have typed in all the stuff that everyone else has done and I still cannot get anything to do anything.


Where in Harry Potter would a wizard or witch go for non magical illness or injury?

I know that St. Mungo's treats illness and injuries caused by magic. What about those injuries or illness that are not caused by magic? Do they go to a Muggle doctor or hospital for treatment? Example Dumbledore and Harry wear glasses where do they go have their eyes examined? I would think wizards/witches being part human would get Muggle related illnesses also.


How to apply modular division correctly?

As described :  $$\frac{a}{b} \bmod{n} = \left((a \bmod{n})(b^{-1} \bmod n)\right) \bmod n$$  When I apply this formula to the case $(1023/3) \bmod 7$: $$\begin{align*}     (1023/3) \bmod 7 &= \left((1023 \bmod 7)((1/3) \bmod 7)\right) \bmod 7 \\                    &= ( 1 \cdot (1/3)) \mod 7 \\                    &= ( 1/3) \mod 7 \\                    &=   1/3 \end{align*} $$ However, the real answer should be $(341) \bmod 7 = \mathbf{5}$.  What am I missing? How do you find $(a/b) \bmod n$ correctly?


How to disable Chrome themes/skins and get default window decorations

Is there a way to disable Chrome's custom window skinning such that it lets the OS draw standard window title bars, borders, etc, in the style I have configured the OS to draw such things with?  I didn't spend all that time with the control panel setting a window style that pleases me just to have applications decide that they know better than me how I want my windows to look. As a practical matter, having each application decide for itself which color cues to use to show "this is the active window" becomes very confusing.  Alternatively, is there a tool somewhere that reads the Windows 7 color and window style settings and produces a Chrome theme that imitates them?


Issues using real names in a soccer player game

Is illegal to use the real player and team names in a game? When I say game could be and desktop, mobile or fantasy game.  If is illegal, is ok to change a little bit names? Instead of using Messi could I use Messsi (or something similar)?  All gambling and statistics soccer websites have permissions to use those names?  Thanks!


Does wearing magic items with armor affect AC negatively?

If I’m wearing a set of full plate  armor and I replace the gauntlets with gauntlets of ogre strength do I lose the AC provided by the full plate as I’m no longer wearing a full set of full plate armor?


Which sentence sounds better:   "Who is she speaking to?"  or  "To whom is she speaking?".  As I see, the both are grammatically correct, whereas books have the former example and in speech I notice the latter.


Dictionaries provide the following-     surely/ˈʃʊəli,ˈʃɔːli/ adverb, used to emphasize the speaker's firm   belief that what they are saying is true and often their surprise that   there is any doubt of this.      certainly/ˈsəːt(ə)nli,-tɪn-/ adverb, used to emphasize the speaker's   belief that what is said is true.    Are there any usage nuances?


Show that ${\sin^4x\over a}+{\cos^4x\over b}={1\over a+b} \implies {\sin^6x\over a^2}+{\cos^6x\over b^2}={1\over (a+b)^2}$

If $${\sin^4x\over a}+{\cos^4x\over b}={1\over a+b}$$  then show that  $${\sin^6x\over a^2}+{\cos^6x\over b^2}={1\over (a+b)^2}$$


Terminal fills with `y` when I answer `yes` to "Are you root?" when installing packages. What's the correct answer?

What is the answer to the question "Are you root?" asked by APT?  I was installing the restricted extras package when I got this message after typing my password.   I typed yes in answer to the question and now the terminal is filling up with the letter y!  What should I do?


Catalan numbers - number of ways to stack coins

How many ways are there to stack coins on top of the other (2D stack) without any coin falling down ? Here's an example for $n=3$:  Now this is most likely just like the monotonic path of Catalan number with up and down instead of up and right but I just don't get why is that ? Well, any advice would be appreciated.


How do I load layers defined by PostGIS views in QGIS 2.18?

I have a layer that is defined by a complex SQL query.   It works fine but I would like to move that complexity out of QGIS and into the data base so I can access it from elsewhere (GeoServer).  I have tried creating a postgres view which represents the layer by using the database manager in QGIS (save as view) and by creating the view from the database itself but when I try and load the layer it is marked with a '!' and I can not select it.  Yes this is a duplicate question (sorry I don't know how to insert a reference to it) but the answers to that question don't work with current (2.18) versions of QGIS.  In particular they do not include the step to click on the schema button which is what I was missing.  I suspect that needing to do this is a bug but I will check this in QGIS 3 before reporting it as such.  The process of adding views is rather unintuitive and 'Get Spatial's explanation is clearer than any of the answers to the original question.  If we dump my question (feel free :) then please ensure that this answer gets added to the original one.  I note that several people besides me have up voted that answer.


Azure DNS does not lookup SPF policies for certain domains

I run my own mail server on an Azure Linux VM with Postfix. Since I was under heavy spam attack I reinforced my mail server security measures.  Without going into the security things, today I noticed something particularly unusual.  Postfix was not getting mail from some well known domains. Only some  #  /var/log/mail postfix/smtpd[40702]: NOQUEUE: reject: RCPT from xxxx.ing.net[xx.xx.xx.xx]: 451 4.3.5 <prvs=2022b5a257=xxxxx@ing.com>: Sender address rejected: Server configuration problem; from=<xxxxxxx@ing.com> to=<xxxxxxxxxx> proto=ESMTP helo=<xxxx.ing.net>  # /var/log/warn postfix/smtpd[32944]: warning: problem talking to server private/spf-policy: Connection timed out   What I dumbly did was to ping for SPF record on ing.com / ing.net  From my Windows box nslookup   ing.com Server:  [8.8.8.8] Address:  8.8.8.8  Risposta da un server non autorevole: ing.com text =          "MS=ms77059065" ing.com text =          "v=spf1 include:_spf.ing.net ip4:91.209.197.6 ip4:89.20.160.55 ip4:78.136.53.254 ip4:95.138.135.251 ip4:92.52.81.2 ip4:146.148.26.249 ip4:83.231.160.132 ip4:83.231.160.128/26 ip4:212.187.169.64/26"         " include:_spf_mx.solvinity.com include:mailplus.nl ip4:24.157.48.85 ip4:141.155.214.85 ip4:160.34.64.28 ip4:192.254.112.185 ip4:118.127.87.207 ip4:128.242.118.200 ip4:62.73.172.35 ip4:83.217.248.35 ip4:91.209.197.7 -all" ing.com text =          "adobe-idp-site-verification=8b81f7b92ccac0b65bab7d47f9fcecaeda6f04ac870b79133d8ac54be7b53534" ing.com text =   From the email server box nslookup  > nslookup > set type=txt > ing.com ;; Truncated, retrying in TCP mode.   From mail server box setting the DNS server to 8.8.8.8 returns the same SPF payload.  Question is: what is causing this issue with TXT DNS resolution in Azure VM? Before blindly changing the system DNS settings, I would like to understand the error and its cause, and why happening only on Azure default DNS


How can I customize a full-screen console background (TTY)?

I used to use full-screen consoles (those opened with Ctrl+Alt+F1...F6) actively and have come to an idea that I would like to try decorating it with a "wallpaper" of a sort (a rather dark and monotonous one of course so that it wouldn't decrease readability), perhaps this could look and feel nice (or not, but I need to try). It would even better if I could set different pictures as different console's background (one for Ctrl+Alt+F1, another for Ctrl+Alt+F2 etc).  The fact the consoles have much higher resolution that pure text mode provides suggests that full-fledged graphical mode is used for them and everything is possible. But how?


Show that if $a$ and $b$ are positive integers then $(a, b) = (a + b, [a, b])$.

Show that if $a$ and $b$ are positive integers then $(a, b)=(a + b, [a, b])$.  I was thinking that since $[a, b]=LCM(a, b)=\frac{ab}{(a, b)}$ that if $d= (a + b, [a, b])$, then $d|[a,b]$ and thus $d|(a, b)$ since $(a, b)|[a, b]$  Then I would just have to prove that $(a+b, (a, b)) = (a, b)$.  Is that the right way to go?


Density of states for arbitrary dispersion relation

If I have a 3D dispersion relation   $E=E(k_x, k_y, k_z)$ I have an equation for the density of states, which is   $D(E)=\frac{1}{\nabla_k E}\int\frac{dS}{(2\pi)^3}$  1) I am confused about the integral. What am I integrating over, exactly? It must have units of the $k$ vector, so it's a k-space integral, but what is the surface that is relevant?  3) Where does that equation come from, how is it derived?


$\sqrt{m}+\sqrt{n}\notin\mathbb{Q}$ Irrationals, Roots Proof

Let $n,m\in\mathbb{N}_0$ and $\sqrt{n}\not\in\mathbb{Q}$. Conclude that $\sqrt{n}+\sqrt{m}\not\in\mathbb{Q}$   What would you recommend me to read to be able to solve this?  Because apart from the case that if $\sqrt{m}\in\mathbb{Q}$ I am kinda stuck.  If $\sqrt{m}\in\mathbb{Q}$ then by "rational+irrational=irrational" the statement holds. (still left to prove tho..)


fixing polygons with "ring not closed" errors

I have a shapefile with a single Polygon feature. This feature has a "ring not closed" geometry error (seen here in QGIS):   I tried using buffering and the GRASS v.clean command as suggested in other answers, but no luck. I also can't find the gap by inspecting the feature visually (it looks perfect).  I need a valid geometry here. Ideally, I'd like to have a Python/command line solution. Any way of doing this manually in QGIS/ArcGIS would also be great.  UPDATE: this shapefile can be downloaded .


I want to know how does Ubuntu install software. For instance I know that executables are moved in /usr/bin and .desktop files in /usr/share/applications but I want to know why and know more about it.


I want to define my loss function as following picture    How can i do this?