In Fragment and in Dialogs I have put some code relative to CRUD operation on my Firestore database. These operations are, e.g., addSnapshotListener , get, update , WriteBatches , ...  The problem is that the user can rotates the screen, leading to a re-execution of those CRUD operations, which are not free - I have the Firebase SPARK Plan so it's actually free but if the limit is reached, no further CRUD operation will be done until the month ends or something like that.  So my question is: should I put these CRUD operations in another callback than onActivityCreated (if yes: how could I put the UI code that I've written in the CRUD operations' onComplete callback, which must be put in onActivityCreated?)? Or: is there another solution, for example a cache system?

In my Android application, when I rotate the device (slide out the keyboard) then my Activity is restarted (onCreate is called). Now, this is probably how it's supposed to be, but I do a lot of initial setting up in the onCreate method, so I need either:   Put all the initial setting up in another function so it's not all lost on device rotation or Make it so onCreate is not called again and the layout just adjusts or Limit the app to just portrait so that onCreate is not called.


According to the  Ubuntu 16.04 uses Python 3 by default and should not even include include Python 2:  Python 3 Python2 is not installed anymore by default on the server, cloud and the touch images, long live Python3! Python3 itself has been upgraded to the 3.5 series.  However, the command line tells me that not only is Python 2 installed, it is actually the default interpreter: $ python Python 2.7.11+ (default, Apr 17 2016, 14:00:29)  [GCC 5.3.1 20160413] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>>   What would be the correct way to set Python 3 as the default interpreter for the whole system? Please do not ask me to create an alias in .bashrc, that is a lame workaround at best.

I type python in a terminal window. I get Python 2.7 and not Python 3.5. According to the docs, Python 3.5 should come preloaded.


According to the C++ Primer 5th Ed by Stanley Lipp:     The standard also reserves a set of names for use in the standard library. The identifiers we define in our own programs may not contain two consecutive underscores, nor can an identifier begin with an underscore followed immediately by an uppercase letter. In addition, identifiers defined outside a function may not begin with an underscore.   All the following did compiled:         g++ -std=c++11 -o test test.cc   int _I=40; int main() {     int __=10;     int _B=20; }   I thought it shouldn't compile ..

It's common in C++ to name member variables with some kind of prefix to denote the fact that they're member variables, rather than local variables or parameters. If you've come from an MFC background, you'll probably use m_foo. I've also seen myFoo occasionally.  C# (or possibly just .NET) seems to recommend using just an underscore, as in _foo. Is this allowed by the C++ standard?


I'd like to see the time-graph of how many points an answer (or a question, I guess?) had.  Can I get at that data (even in a raw form, to shove into Excel!)

Is it possible to view a graph showing a post's up and down votes over time?   Not who voted for it, just "vote received at [timestamp]". I know if a user has enough rep they can see the total up and down votes their post has received so far, but I'm not aware of being able to see the history of votes on a post.


Let $a_i , b_i \geqslant 0$  $\forall i \in \{1 , 2 , 3 , .... , n\}$ Prove that $$min\{\frac{a_i}{b_i}\} \leqslant \frac{\sum_{i=1}^n a_i}{\sum_{i=1}^n b_i} \leqslant max\{\frac{a_i}{b_i}\}$$ Given that $min\{...\}$ and $max\{...\}$ equals to the minimum and the maximum element in the set.  I don’t know how to deal with minimum and maximum. I would like some hints (or solution) please. Thank you.


So my SSL is using SNI, Bing doesn't want to index my site because of that and also some other sites are having problems. Such as reddit.  Is it possible to detect if client supports SNI?  I was thinking something like:  if (sni_support)  - force https  else  - http   I'm using latest Apache2 on Ubuntu.

I have Apache 2.2 with mod_ssl and a bunch of sites in HTTPS on the same IP/port with VirtualHosting, so client must support SNI to connect to those virtual hosts.  I would like to configure my server the following way:  When a user types www.dummysite.com and his browser supports SNI (Server Name Indication), any HTTP request is redirected to https:// where an HSTS header is sent. But if the browser doesn't support SNI then the request is served by HTTP.  The above rule, stated as is, is actually a fallback rule for those people that still run old browsers, as Mozilla and Chrome don't have this problem, just to avoid leaving these users out of the site.  I would like to do this redirecting at the Apache config level, perhaps with a filter on the user agent. I wouldn't like to touch running applications except making sure that no direct http:// references are present (otherwise they imply a security warning)  [Edit] (while editing the question I forgot the question): what is the list of SNI-enabled user agents to redirect?


How do you pronounce forte?  Fort or for-tay?

I've always heard people say something like     "Pronunciation is not my [for-tay]"   ... but I feel that I've heard that the correct pronunciation is     "Confusing people is my [fort]"   What is the proper way to pronounce this word?


The achievements dialog drop-down in the top bar shows the recent achievements across all sites. Each entry has a site-specific icon next to it, so you know where it's from. Badges, however, seem to be displayed relative to the site that you're on.  Here is the view from :    Here is the view from :    Here is the view from :    This seems like a bug; the badge icon should also stay with the site.

It's so cool that the notification reminds you of the colour of badge you've earned. But I am a little puzzled by the symbols:      Is it feasible to use the symbol from the earned site? At the moment it uses the symbol from the site I happen to be on (as you can see by looking to the left of the dropdown in each case.)


Does there exist an epimorphism from the ring $\mathbb{Z_{24}}$ onto the ring $\mathbb{Z_{7}}$? an epimorphism is a surjective homomorphism Could someone give me an idea how to know this? to be honest I have no idea

Let $A$ and $B$ be rings having respective characteristics $n$ and $k.$ Show that if there exists a ring homomorphism $f : A \to B$, then $k$ divides $n$. I don't know how to start this problem. If someone has tips, I would appreciate it.


I am trying to solve this inequality by induction. I just started to learn induction this week and all the inequalities we had been solved were like an equation less than another equation (e.g. $n! \geq 2^n$) So I am confused how to prove an inequality that is less than a particular value like the following problem? Thanks in advance.     $$\frac1{1^2}+\frac1{2^2}+\frac1{3^2}+\ldots+\frac1{n^2}<2$$

So I'm a bit stuck on the following problem I'm attempting to solve. Essentially, I'm required to prove that $\frac{1}{2^2}+\frac{1}{3^2}+\cdots+\frac{1}{n^2} < 1$ for all $n$. I've been toiling with some algebraic gymnastics for a while now, but I can't seem to get the proof right. Proving it using calculus isn't a problem, but I'm struggling hither.


I am stuck with this one, have tried apt-get install -f, dpkg --configure -a and they both tell me about the same.   I have no held packages (dpkg -l|grep -i '^h' is empty). Where do I start to look?  # apt-get upgrade Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies:  compiz-plugins : Depends: compiz-core (= 1:0.9.13.1+17.10.20170901-0ubuntu1) but 1:0.9.12.2+16.04.20160823-0ubuntu1 is installed                   Depends: compiz-plugins-default (= 1:0.9.13.1+17.10.20170901-0ubuntu1) but 1:0.9.12.2+16.04.20160823-0ubuntu1 is installed  libcompizconfig0 : Depends: compiz-core (= 1:0.9.13.1+17.10.20170901-0ubuntu1) but 1:0.9.12.2+16.04.20160823-0ubuntu1 is installed  libgail-3-0 : Depends: libgtk-3-0 (= 3.22.25-0ubuntu0.1) but 3.18.9-1ubuntu3.3 is installed  libmetacity1 : Depends: metacity-common (= 1:3.26.0-1) but 1:3.18.7-0ubuntu0.3 is installed                 Depends: libgtk-3-0 (>= 3.20.0) but 3.18.9-1ubuntu3.3 is installed  metacity : Depends: metacity-common (= 1:3.26.0-1) but 1:3.18.7-0ubuntu0.3 is installed             Depends: libgtk-3-0 (>= 3.21.5) but 3.18.9-1ubuntu3.3 is installed  unity : Depends: libunity-core-6.0-9 (= 7.4.0+16.04.20160906-0ubuntu1) but 7.5.0+17.10.20171010-0ubuntu1 is installed E: Unmet dependencies. Try using -f.   EDIT: As one answer comments, there are some mixed versions. This is because I tried to do a dist-upgrade to get rid of the error earlier. Apparently it has changed the error, but I believed it to be the same error, and didn't find the dist-upgrade relevant. My bad. I'll look into remove those pkgs then.  EDIT2: I don't think this is an exact duplicate of the two mentioned, at least not on at level I can comprehend.  QUESTION ANSWERED: I think the answers froms user535733 and karel are the ones that helped me. I'm sorry I do no seem to be able to accept the answer officially - could that be because the question is marked as a duplicate? I will try to accept again later.  Anyway: I pegged my installation at 16.04 (apt-get install -t xenial) and went around disabling the 17.10 packages. But then I got lost, gave up and made a clean 17.10 installation. Thanks for your time :-)

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


i was trying to uninstall wine, but the command i got from this site destroyed my ubuntu machine. the command was "sudo apt-get remove wine*" or --purge in place of remove would do same thing. it uninstalled everything. luckly i had everything on an external hdd.  so i reinstalled 12.04 64bit. started up virtual box, made a virtual machine for 12.04 32bit. (was going to test wine apps in it). the installation process was ok. but after reboot of the virtual machine, i get low graphics window at bootup. then i deleted and tried again. same thing.  i gave the virtual machine:  2 CPU cores  2GB ram  128MB video ram  3d & 2d acceleration.  16GB HDD.  my ubuntu 64bit machine has: AMD 4 core 16GB ram nvidia gtx 650 1TB+  It was working before the melt down. soo im not getting it...

I'm using currently Ubuntu 12.04 LTS as a host machine, and I've virtualized three machines:   a Xubuntu 12.04 guest a Windows 7 guest a Ubuntu 12.10 guest   All the guests have the same VirtualBox default settings, but Ubuntu 12.10 is slower!  The installation took 1h 40 min! (Normally, it takes 40 minutes.) Now it is impossible to use it, and all operations are very, very slow.  I'm using VirtualBox version 4.2.4.  Any ideas?  Why is it slow? And how can I make it faster?


I'll make this more simple than before, since the answer did not work.    I need the first shirt with the lines behind it look like this:    I just took the lasso tool to create this example, which is not what I want to do. I want to keep it a vector image but have the same outcome.

Im new to Illustrator and have found the clipping mask is not so easy compared to Phtoshop. Could any one tell me how i can make this line texture a clipping mask over the circle?


Consider the set of all mappings of class $C^1$ defined from $[-1,1]$ into $\mathbb{R}$.  Consider the two norms  $N_1=\sup_{x\in[-1,1]}|f(x)|$ and $N_2=|f(0)|+\sup_{x\in[-1,1]}|f'(x)|$.  Are they equivalent?

Consider the space $C^1([0,1])$ and the function $d:C([0,1])\times C([0,1]) \to \mathbb R$ defined as $d(f,g)=|f(0)-g(0)|+sup_{x \in [0,1]}|f'(x)-g'(x)|$. Decide whether the metrics $d$ and $d_{\infty}$ are topologically equivalent in $C^1([0,1])$ (where $d_{\infty}=sup_{x \in [0,1]}|f(x)-g(x)|)$  My attempt at a solution:  If two metrics are topologically equivalent, then they have the same convergent sequences. Honestly, I couldn't do anything. I am trying to define a sequence of functions $\{f_n\}_{n \in \mathbb N}$ such that $f_n \to f$ in, for instance, $(C^1([0,1]),d)$ but $f_n \not \to f$ in $(C^1([0,1]),d_{\infty})$. Could it be this two metrics are topologically equivalent? If this is the case, how could I prove it? If not, I would appreciate any hint to find an adequate sequence of functions that works for what I am trying to prove.


Error: Read only property   'StoreFrontController.productDisplay.quantity'   Visualforce :      <apex:page controller="StoreFrontController" tabStyle="Product__c" > <apex:form>      <apex:pageBlock title="Our Products">         <apex:pageBlockSection columns="1">             <apex:pageBlockTable value="{!products}" var="pitem">                 <apex:column headerValue="Product">                 <apex:outputText value="{!pitem.Name}"/>                 </apex:column>                 <apex:column headerValue="Condition">                 <apex:outputText value="{!pitem.condition}"/>                 </apex:column>                <apex:column headerValue="Price">                 <apex:outputText value="{0,number,currency}" style="text-align: right;">                 <apex:param value="{!pitem.Price}"/>                 </apex:outputText>                    </apex:column>                 <apex:column headerValue="Stock">                 <apex:outputText value="{!pitem.stock}"/>                 </apex:column>                 <apex:column headerValue="Qty to Buy">                 <apex:inputText value="{!pitem.quantity}" rendered="{! pitem.Stock}"/>                 <apex:outputText value="Out of Stock" rendered="{! NOT(pitem.Stock)}"/>                 </apex:column>             </apex:pageBlockTable>         </apex:pageBlockSection>         <apex:pageBlockSection>             <apex:commandButton title="Add to Cart" value="{!addToCart}"/>         </apex:pageBlockSection>     </apex:pageBlock>     <apex:pageBlock title="Cart Contents" id="shopping_cart">         <apex:outputText value="{!cartContents}" escape="false" />     </apex:pageBlock>     </apex:form> </apex:page>   **Apex Class : **      public class StoreFrontController {     list<productDisplay> prd;     list<productDisplay> shoppingCart = new list<productDisplay>();      public pageReference addToCart()     {         for(productDisplay ploop : prd)         {             if(0<ploop.quantity)             {                 shoppingCart.add(ploop);             }         }         return null;     }     public String getCartContents()     {         if(0==shoppingCart.size())         {             return '(Empty)';         }         String msg = '<ul>\n';         for(productDisplay pdLoop : shoppingCart)         {             msg += '<li>';             msg += pdLoop.name + ' (' + pdLoop.quantity + ')';             msg += '<li>\n';         }         msg += '</ul>';         return msg;     }         public list<productDisplay> getProducts()     {         if(prd == null)         {             prd = new list<productDisplay>();             for(product__C item : [ SELECT Id, Name, quantity__c, condition__c, Price__c,                                         stock__c FROM product__c])              {                 prd.add(new productDisplay(item));             }         }         return prd;     }     public class productDisplay {     public Product__c p;     productDisplay(Product__c itemDisplay) {         this.p = itemDisplay;     }     public String name     {         get{return p.name;}     }     public String condition     {         get{return p.condition__c;}     }     public Decimal price     {         get{return p.price__c;}     }      public boolean stock     {         get{return(0<p.Stock__c);}     }     public Decimal quantity {get{return(p.Quantity__c);}     } } }


i want to create a array of ArrayAdapter and array of List, to use in some spinners.   This is my script:      String[] items = new String[]{"Select","A","B", "C", "D"};     ArrayAdapter<String>[] adaptador;     List<String>[] List;  .....     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_inventario);         restart_spinner(11);     }  public void restart_spinner(int sp) { List[sp] = new ArrayList<>(Arrays.asList(items2)); adaptador[sp] = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, List[sp]); spinner = (Spinner) findViewById(getResources().getIdentifier("p"+sp, "id", getPackageName())); spinner.setAdapter(adaptador[sp]); }   but i get a java.lang.NullPointerException in this line List[sp] = new ArrayList<>(Arrays.asList(items2));  How i can do to fix that?

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Here what i am trying to achive is to print a anchor pane by getting the default printer and here is the code.  public class printnodeController { @FXML private AnchorPane print; public void print (){      Printer printer = Printer.getDefaultPrinter();     PageLayout pageLayout         = printer.createPageLayout(Paper.A4, PageOrientation.PORTRAIT,  Printer.MarginType.HARDWARE_MINIMUM);     PrinterAttributes attr = printer.getPrinterAttributes();     PrinterJob job = PrinterJob.createPrinterJob();     double scaleX         = pageLayout.getPrintableWidth() /  print.getBoundsInParent().getWidth();     double scaleY         = pageLayout.getPrintableHeight() /  print.getBoundsInParent().getHeight();     Scale scale = new Scale(scaleX, scaleY);     print.getTransforms().add(scale);      if (job != null && job.showPrintDialog(print.getScene().getWindow())) {       boolean success = job.printPage(pageLayout, print);       if (success) {         job.endJob();        }     }     print.getTransforms().remove(scale);  } }   but i am getting this error:      java.lang.reflect.InvocationTargetException     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)     at java.lang.reflect.Method.invoke(Unknown Source)     at     com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)     at       com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)     at java.lang.reflect.Method.invoke(Unknown Source)     at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)     Caused by: java.lang.NullPointerException     at application.printnodeController.print(printnodeController.java:25)     at application.Main.main(Main.java:47)     ... 11 more     Exception running application application.Main   i had tried searching but didnt find any solution ; please help  new to this site Thankyou in advance.


How do you stop the notifications on the notes that says the cellular data is off? I know it is off. I turned it off. I do not want my notes on my phone and my iPad to sync. Both places gets messed up.

On iOS 7, there is a feature under Cellular in Settings called: Use Cellular Data For:. This lists all of the apps I have on my iPhone 4 with individual On/Off Switches to disable or enable cellular data. So, I disable it on several of my apps, one of which being Music. When I open my Music app, it tells me…     Cellular Data is Turned Off for "Music"   You can turn on cellular data for this app in Settings.   This alert does not occur once, but every time I clear the Music app from my multitasking and re-open it. Is there a way to dismiss this alert once and forever?  The alert looks something like this, but for Music:


He as well as his friends _____ going to play cricket in that playground.

My question arises from , where OP asks whether he should use the singular or plural verb form after "the title, as well as the tone,"  As luck would have it, when I searched Google Books for , I found...        ...and...        At the risk of having this question closed as just peeving, I feel that the first one should have been plural "err", because without the commas it seems to me both "the title" and "the tone" have more or less equal status as "joint" subjects of the verb, making it plural.  On the other hand, I feel the commas in the second example effectively demote "the tone" to "parenthetical" status (the clause is almost incidental). Since this encourages us think of "the title" as the primary subject, it should have been singular "derives".  I'm no great fan of "grammatical rules", but it seems weird to me that the only two relevant examples for this specific wording should both (in opposite ways!) contradict my inclinations.  What's going on?


every time i turn off Real-time protection, its off for a few days (maybe 3 days?) then it automatically turns itself on again, how do i stop it?

I just upgraded to Win 10 (RTM build). I have disabled the built in AV's (Defender) real time protection because I do not run it, never did and have never gotten a virus (and I've had a computer for 30 years).  I was able to disable real time scans by turning on the Group Policy's Disable Defender Policy. But this disables the application entirely. Is it possible to use this profile (which I used with Win 7's Security Essentials) with Win10 Defender:   Real time scan off Scheduled scans (2AM) active On demand (shell integration right click) scans active   ?  Or do I have to install a 3rd party scanner? I already run  Premium,  and  (those are protecting in real time, as their impact on performance is minimum), but I would really like to avoid a 3rd party AV.  TIA


I have mail() function that sends email and seems to me the problem is not in the mail headers but stil I got 2 positions in the mail SPAM assignation that makes some email providers to classify my emails as spam. This is : 0.0 URIBL_BLOCKED          ADMINISTRATOR NOTICE: The query to URIBL was                          blocked.  See                          http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block                           for more information.                          [URIs: shoppingbulgaria.com]   0.8 BAYES_50               BODY: Bayes spam probability is 40 to 60%                          [score: 0.5000]  -0.0 SPF_PASS               SPF: sender matches SPF record  -0.0 SPF_HELO_PASS          SPF: HELO matches SPF record   0.1 MIME_HTML_ONLY         BODY: Message only has text/html MIME parts   0.0 HTML_FONT_LOW_CONTRAST BODY: HTML font color similar or                          identical to background   0.0 HTML_MESSAGE           BODY: HTML included in message   0.0 HTML_IMAGE_ONLY_32     BODY: HTML: images with 2800-3200 bytes of                          words   0.1 DKIM_SIGNED            Message has a DKIM or DK signature, not necessarily                          valid  -0.1 DKIM_VALID_EF          Message has a valid DKIM or DK signature from                          envelope-from domain  -0.1 DKIM_VALID_AU          Message has a valid DKIM or DK signature from                          author's domain  -0.1 DKIM_VALID             Message has at least one valid DKIM or DK signature   2.5 PHP_SCRIPT             Sent by PHP script   2.2 HAS_X_OUTGOING_SPAM_STAT Has header claiming outbound spam scan                          - why trust the results?  As you can see last 2 positions make the difference of being marked as SPAM or not: 2.5 PHP_SCRIPT             Sent by PHP script 2.2 HAS_X_OUTGOING_SPAM_STAT  Unfortunately I could not find any information and explanation for this: 2.5 PHP_SCRIPT             Sent by PHP script  Why the fact its been sent by php script could be a reason for being marked as SPAM? And what this means: 2.2 HAS_X_OUTGOING_SPAM_STAT Has header claiming outbound spam scan                      - why trust the results?  $headers =''; if(isset($p['from_name'])) $headers .= "From: ".official_site_name." <".$p['from_email'].">\r\n"; if(isset($p['from_email'])) $headers .= "Reply-To: ".official_site_name." <".strip_tags($p['from_email']).">\r\n"; else $headers .= "Reply-To: ".official_site_name." <".official_mail_sender.">\r\n"; $headers .= "Return-Path: <".official_mail_sender.">\r\n"; if(!empty($p['cc'])) $headers .= "CC: <".strip_tags($p['cc']).">\r\n"; if(!empty($p['bcc'])) $headers .= "BCC: <".strip_tags($p['bcc']).">\r\n"; $headers .= "Content-Type: text/html; charset=UTF-8\r\n"; $headers .= "Content-Transfer-Encoding: 8bit\r\n"; $headers .= "X-Mailer: PHP/". phpversion() ."\r\n" ; $headers .= "MIME-Version: 1.0\r\n"; $random_hash = md5(date('r')); $body='  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> <title>'.$p['subject'].'</title>  Body text';  mail("<".$p['to'].">", '=?utf-8?B?'.base64_encode(strip_tags($p['subject'])).'?=', $body, $headers, "-f ".official_mail_sender."");  The body has normal registration welcome text.. Thanks for any help

This is a tricky one and I've always relied on techniques, such as permission-based emails (i.e. only sending to people you have permission to send to) and not using blatantly spamish terminology.  Of late, some of the emails I send out programmatically have started being shuffled into people's spam folder automatically and I'm wondering what I can do about it.  This is despite the fact that these particular emails are not ones that humans would mark as spam, specifically, they are emails that contain license keys that people have paid good money for, so I don't think they're going to consider them spam  I figure this is a big topic in which I am essentially an ignorant simpleton.


Someone please help me identify the S at the top left corner of my picture

I'm concerned about an app on my child's phone. I saw an app icon in the notification area that looked strange (Andy Android head, slightly tilted as its icon).  How can I find out what app it is from just having seen that icon in the notification bar?


I read  and understood that you can only be using either biblatex or natbib. However, I have been able to compile just fine with citations without writing neither \usepackage{natbib} nor \usepackage{biblatex}. To compile, I use the macOS terminal and run:     pdflatex     bibtex     pdflatex     pdflatex.   I am using texlive.  So, which package I am using when I don't specify the package? Or how is it possible that my file is compiling just fine when I am not writing specifically \usepackage ?

According to , biblatex and natbib are packages while biber and bibtex are backends. If I don't specify either any package or any backend, it still compiles fine. Which package and backend combination is being used in this case?  demo.tex  \documentclass{article} \begin{document}  \nocite{*} \bibliographystyle{ieeetr} \bibliography{pub}  \end{document}   pub.bib  @article{janssen1996evaluation,     title={Evaluation of the DNA fingerprinting method AFLP as a new tool in bacterial taxonomy},     author={Janssen, Paul and Coopman, Renata and Huys, Geert and Swings, Jean and Bleeker, Marjo and Vos, Pieter and Zabeau, Marc and Kersters, Karel},     journal={Microbiology},     volume={142},     number={7},     pages={1881--1893},     year={1996},     publisher={Soc General Microbiol} }  @article{vos1995aflp,     title={AFLP: a new technique for DNA fingerprinting},     author={Vos, Pieter and Hogers, Rene and Bleeker, Marjo and Reijans, Martin and Van de Lee, Theo and Hornes, Miranda and Friters, Adrie and Pot, Jerina and Paleman, Johan and Kuiper, Martin and others},     journal={Nucleic acids research},     volume={23},     number={21},     pages={4407--4414},     year={1995},     publisher={Oxford Univ Press} }


I cannot pay for courier charges for UK visit visa for my family. I'm using a UPS label. I tried to pay as a group but I cannot. Do I have to apply individually?

We are sponsoring a family to visit us in UK as friends from Madagascar for two weeks. They have a 6 year old and a 16 month old.   Do the kids need their own visas, and are they the standard visitor visa or a special child visa?   Also, when I try and apply on the website I can only apply for one person so how do I apply for all the individuals in the family?   I have looked on the Immigration website and can't find the answers I need.


I need an empty list with the following structure so I can later populate it without getting out of range errors:  [5[2[]]]  i.e.: [[[], []], [[], []], [[], []], [[], []]]  So I tried declaring it this way: [[[]]*n]*m / n=2, m=5  But * is copying references, so if i do something like this:  >>> foo = [[[]]*2]*5 >>> foo    [[[], []], [[], []], [[], []], [[], []]]  >>> foo[3][0] = 1 >>> foo    [[1, []], [1, []], [1, []], [1, []]]   The assigned value gets copied to all sub-lists with the same reference.  I can fix this by declaring foo's sizes "statically" like:  foo = [[[], []], [[], []], [[], []], [[], []]]  But I need a parametric way like the previous example.  I would like to know if there's a parametric pythonic/compact way of of declaring and empty list of lists (like with n and m in the example), where all its elements have individual references.  Thanks in advance!

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I want a unix command to check the directory is empty or not(need to exclude . and ..) ?  thanks in advance.

From a shell script, how do I check if a directory contains files?  Something similar to this  if [ -e /some/dir/* ]; then echo "huzzah"; fi;   but which works if the directory contains one or several files (the above one only works with exactly 0 or 1 files).


$$\frac{1^2}{1!}+ \frac{2^2}{2!}+ \frac{3^2}{3!} + \frac{4^2}{4!} + \dotsb$$  I wrote it as: $$\lim_{n\to \infty}\sum_{r=1}^n \frac{(r^2)}{r!}.$$  Then I thought of sandwich theorem, it didn't work. Now I am trying to convert it into difference of two consecutive terms but can't. Need hints.

For some series, it is easy to say whether it is convergent or not by the "convergence test", e.g., ratio test. However, it is nontrivial to calculate the value of the sum when the series converges. The question is motivated from the simple exercise to determining whether the series $\sum\limits_{k=1}^{\infty}\frac{k^2}{k!}$ is convergent. One may immediately get that it is convergent by the ratio test. So here is my question:     What's the value of $$\sum_{k=1}^{\infty}\frac{k^2}{k!}?$$


I have the following query (SQL SERVER):  select id,id_nivel_estructura from estructuras_empleado where id in (1,2)   The result is the following:    but I want to display in columns in the following way:   1 | 4 | 67 | 146 | 345 | 2158   2 | 3 | 34 | 267 | 345 | 2152   Could you help me?

Trying to find some simple SQL Server PIVOT examples.  Most of the examples that I have found involve counting or summing up numbers.  I just want to pivot some string data.  For example, I have a query returning the following.  Action1 VIEW   Action1 EDIT   Action2 VIEW   Action3 VIEW   Action3 EDIT     I would like to use PIVOT (if even possible) to make the results like so:  Action1 VIEW EDIT   Action2 VIEW NULL   Action3 VIEW EDIT     Is this even possible with the PIVOT functionality?


I'm a noob, so I'm probably messing this up somehow, but can anyone tell me why the materials preview looks nothing like the render? Below, I have two screenshots to illustrate this (the better looking one is the material preview). Using Cycles fixes it, but I'm curious as to why it's not working properly in eevee. Thanks for any help!

I want to export my objects to unity, but in blender I`m using Eevee engine. However the light in rendered more and material preview mode is completely different, which impacts the colors of objects. Which one can i trust to see the true final colors of the objects so that they will be the same when i export them to unity?


I want to create jquery listener to check internet connectivity.         function checkInternetConnection()     {         onConnectionClosed:function(){             dialog.show("Connection closed please wait");         }         onConnectionOpened:function(){             dialog.hide();         }     }          $(document).ready(function(){         checkInternetConnection();     }); <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>     So, when the connection is turned off, I want to show a dialog to user. When the connection is back I want to hide the dialog. How can I do this?

How to detect the Internet connection is offline in JavaScript?


I must prove that the ring of formal power series $\mathbb{R} [[x]]$ is a Euclidean domain.    So I started and I think I should start with for each nonpower series $P$, define $f(P)$ as degree of the smallest power of $x$ occurring in $P$. In particular, for two nonzero power series $P$ and $Q$, $f(P) < f(Q)$ iff $P$ divides $Q$.

Let $k$ be a field. Let $R$ be the formal power series ring $k[[x]]$. Define $N$ on $R \setminus \{0\}$ as follows: $N(f)$ is the smallest $n$ of which the coefficient of $x^n$ in $f$ is nonzero.  (a) Prove that $R$ is a Euclidean domain with Euclidean norm $N$.  (b) For $a$, $b$, $a+b$ nonzero elements of $R$, prove that $N(a+b)$ cannot be bounded as a function of $N(a)$ and $N(b)$.  (c) Prove that if $a$ and $b$ are two power series such that $b$ does not divide $a$ (and $b \neq 0$), there are infinitely many pairs $(q, r)$ for which $a = bq + r$ and $N(r) < N(b)$.


Suppose there are two identical capacitors of capacitance C and one of them is charged to a potential V and gets a charge q. The energy stored in this capacitor is \$1/2cv^2\$ or \$q^2/2c\$ . Now this capacitor is connected with the uncharged capacitor. Now the net energy of this system will be \$q^2/4c\$ . How is the other half of the energy lost ? Where does it go ?

The energy stored in a capacitor is $$ U= \dfrac{1}{2} CV^2 $$    So when I have a 1F supercap charged to 1V the energy is 0.5 J. When I connect a second supercap, also 1F in parallel the charge will distribute and the voltage will halve. Then    $$ U = \dfrac{1}{2} 2F (0.5V)^2 = 0.25 J $$  What happened to the other 0.25 J?


This is an exercise from Rotman's An Introduction to the Theory of Groups:     Exercise 3.30. Let $G$ be a group of order $2^mk$, where $k$ is odd. Prove that if $G$ contains an element of order $2^m$, then the set of all elements of odd order in $G$ is a (normal) subgroup of $G$. (Hint: Consider $G$ as permutations via Cayley's theorem, and show that it contains an odd permutation.)   My attempt: Let $a\in G$ with $|a|=2^m$. Following the hint, we imbed $G\hookrightarrow S_G$ and identify $G$ with its image. The element $a$ is the product of $k$ disjoint $2^m$-cycles (since $a$ is a regular permutation) and thus $a$ is an odd permutation. Then $G$ has exactly $2^{m-1}k$ odd permutations. Any element in $G$ of odd order is an even permutation. However, the converse is false. I am unable to proceed. I think I must be missing something. Any hints will be appreciated!

I searched in the existing post and didn't find this problem. I am sorry if someone else have already posted.     Let $G$ be a group of order $2m$ where $m$ is odd. Prove that $G$ contains a normal subgroup of order $m$.   There is a hint:     Denote by $\rho$ the regular represetation of $G$: find an odd permutation in ${\rho}(G)$.   I don't know how to find an odd permutation in the regular representation. I am wondering whether all the elements of $G$ of odd order form this subgroup in this case.  Thanks.


function F (v) {     var v = v;     this.fun = function f () {             console.log(v);     }; };  var i = new F(1);   i.fun();    Just to clarify, I don't this my question is solved by a knowledge of closures. To my understanding, i is just: {fun: function f () {console.log(v)}}. So how is i.fun() able to access v - one of the variables in a constructor function that only helped to make i?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


For reference im using an AVR Atmega 328p, and the servo specs i'll be using says this:   Pulse Cycle: 20 ms (I assume this means the "period")  Pulse Width: 600-2400 µs   So from my understanding, using fast PWM and lets say a 1Mhz clock. I make the Width by setting 2 values. One when it reaches TOP-whatever width (lets pretend 1800 ms, I think people use ICR1 for this) and then the top (I think they usually use OCR1A here).   So the time between ICR1 and OCR1A (Which is the top) is where I turn the "Pin" to the Servo on correct? And then it turns off when OCR1A ends  IE: Turn on when it reaches ICR1, turn off when it reaches OCR1A. If I want a width of 1.8 ms i'd need to make that 1800 steps correct? Since 1800 "ticks" would be 1.8ms (If Im understanding my units correct)  The pulse cycle is where I get confused. That would just be the "TOP" value right? IE: if I need a 20ms pulse cycle. and every tick at 1MHz is 1/1000 of a milliseconds, so to do 20ms pulse cycle, ill need 20000 ticks. because every tick is 1/1000 of a ms  Am I thinking of this correctly? I think the "Ticks" with the CPU Frequency and then trying to get that figured out with cycles and widths is just sort of throwing me for a loop.

I wanted to control the direction of servo motor with a switch. I am using an Atmega32.  Outputs are PIND4 and PIND5 and the input is PINA3, but the two servo motors turn only in 1 direction.  #ifndef F_CPU  #define F_CPU 1000000UL   #endif  #include <avr/io.h> #include <util/delay.h> #include <avr/interrupt.h>   int main(void) { DDRD= 0xFF ; DDRA=0x00; PORTA =0x00; // FAST PWM TCCR1A |= 1<<COM1A0 | 1<<COM1A1 | 1<<WGM11 |1<<COM1B0|1<<COM1B1 ; TCCR1B= 1<<WGM12|1<<WGM13 ; ICR1 = 19999 ;  TCCR1B |=1<<CS10 ; while (1) {    if(PORTA==0x08) //if pina3 is 1    {     OCR1A = ICR1 -2000 ;   //turn servo 1     _delay_ms(1000);          OCR1B=ICR1-2000;    //turn servo 2     _delay_ms(1000);     }     if(PORTA==0x00)// if pina3 is 0     {       OCR1A = ICR1 -900 ; //turn servo 1 in the other direction       _delay_ms(1000);               OCR1B=ICR1-900;     //turn servo 2 in the other direction       _delay_ms(1000);      } }       return 0 ;  }


How can you stop a tail -f command after seeing a specific string/word?  I'm trying to follow an expanding log and stop the tail after finding a specific word. Is there any kill command for that? I'm just starting with UNIX.

I've got a CI server with a command-line interface that allows me to remotely kick-off a job (jenkins CI server and the jenkins-cli.jar tool).  After I kick the job off I tail -f the log (sorry for the messy command):  ssh -t my-jenkins-host.com "tail -f \"/var/lib/jenkins/jobs/$job_name/builds/\`ls -ltr /var/lib/jenkins/jobs/$job_name/builds/ | grep '^l' | tail -n 1|awk '{print \$9}'\`/log\""   After the job successfully completes, usually after at least 5 minutes, I get the following line on the output:  Finished: SUCCESS   Is there a good way to stop tailing the log at this point? i.e. is there like a tail_until 'some line' my-file.log command?  BONUS: extra credit if you can supply an answer that returns 0 when SUCCESS is matched, 1 when FAILURE is matched, and your solution works on mac! (which i believe is bsd based)


Penzias and Wilson famously discovered the CMB as a signal that they failed to be able to account for after removing all other known radio-sources. It's apparently close to the same strength in all directions etc. etc. Is there an analogue for gravitational waves - a gravitational echo of the Big Bang? Can we/have we detected it or would the precision required be too great for modern technology?

The recent discovery by the LIGO made me wonder about this.  We know that there exists a CMBR, Cosmic Microwave Background Radiation, a blanket of electromagnetic energy covering the universe, made by the Big Bang.  But, the big bang was an explosive event. The huge "shockwave" made by it sent ripples in space time. (Primordial gravitational waves)  Wouldn't these ripples flood the universe creating sort of a Cosmic Gravitational Background Radiation (not exactly radiation)?  If such waves do flood the universe, couldn't a much more sensetive version of LIGO be able to detect this and use it as a contrast to create "gravitational telescopes"?


In Episode V, what did Vader mean when he told the Emperor:      Obi-Wan can no longer help him?    Help him in what way? Obi-Wan's Force ghost 'had been' helping Luke since the Battle of Yavin which happend 3 years earlier. Were Vader and Palpatine just ignorant of the fact that living Force-sensitives could commune with the dead?

OK, I understand that Obi-Wan turned into a force ghost when Vader struck him down, but why was Vader surprised by the lack of a body? It's not the transition into a force ghost but Vader's reaction that bugs me.


I'm using this code:       function ucfirst(field) {        field.value = field.value.substr(0, 1).toUpperCase() +       field.value.substr(1); }   this is working if i have a city like california ==> California. But if I have new york it will not convert the first letter.   Any tips how to make this code work?

Is there a simple way to convert a string to Title Case? E.g. john smith becomes John Smith. I'm not looking for something complicated like , just (hopefully) some kind of one- or two-liner.


I was presented a correlation graph with data set A Vs data set B and there was no correlation. Then I was shown another graph with Y=A x B Vs B and there there was correlation. As Y is calculated from B I thought there should automatically be a correlation between Y and B so why doing that correlation graph. But I did some simulation with randomly generated sets of B (A staying the same) and it was not always correlated. Does anyone has a mathematical explanation why Y = A x B should or should not be correlated to B Thanks

Suppose you fit a model $y = x_1 + x_2 + x_1\times x_2$. Are there any practical implications for estimation of the interaction effect if $x_1$ and $x_2$ are correlated?   I understand there could be collinearity issues if $x_1$ and $x_2$ are very correlated but that shouldn't affect the interaction term right?


How will the SEO be affected if I move a website to new host, the domain name will remain the same and old urls map to new ones. The owner wants to update some content (add and remove) on the new sites pages? Will adding content negatively affect the SEO of the pages?

I have been hosting in a server from last 2 years. I am planning to change the hosting server. Before I change the hosting server I would like to know whether it affects my site's rankings or not?


I already know there are a few vegan egg replacements, such as:   Aquafaba Coconut milk One tablespoon of apple puree with 1 tablespoon of dense oil (coconut oil or corn oil I guess) Chickpea flour with some starches   I know that each one of these, as well as others I don't know → aren't multipurpose as eggs are and thus and should be used for different groups of recipes respectively.  What can replace eggs when making a vegan sponge cake?

I spent about 2 1/2 years as a lacto-ovo vegetarian but, I gave up eggs in October. The problem is that I really like cake. Unfortunately, the cake recipes that I've found that don't use eggs produce very dense cakes. Is there a way around this?


While trying assignment questions of Field Theory of my class I am unable to solve this particular problem.  Let $ f/g \in K(x) $ with f/g not belonging to K and f, g a relatively prime in K[x] and consider the extension of K by K(x).  Then prove that x is algebraic over K(f/g) and [ K(x) : K(f/g) ] = max ( deg f, deg g). I have showed it algebraic by considering polynomial p(a)=  f/g × g(a) - f(a). But I am unable to prove the result related to degree. Edit 1: This question had some part which I am unable to solve : The assignment $ x \to f/g $ induces a homomorphism $\sigma : K(x) \to K(x)$ such that $\frac{\phi(x)}{\psi(x)} \to \frac{\phi(f/g)}{\psi(f/g)}$. I am not well in problems in which it is to be proved that an homomorphism is induced. Can you please tell basic philosophy behind it? Thanks!!

Let $F$ be a field and $x$ transcendental over $F$. Let $y=f(x)/g(x)$ be a nonconstant rational function with relatively prime polynomials $f,g\in F[x]$. Prove $[F(x):F(y)]=\max(\deg f,\deg g)$.  My attempt: By replacing $y$ with $\frac{1}{y}$ if necessary we assume $\deg g\geq\deg f$. By the Euclid algorithm we assume $\deg g>\deg f$. Then $\deg g=\max(\deg f,\deg g)$, let $n=\deg g$. Let $R(t)$ be this polynomial $$R(t)=yg(t)-f(t)=\frac{f(x)}{g(x)}g(t)-f(t)$$ Then $\deg R=\deg g=n$ because $n=\deg g>\deg f$. The coefficients of $R(t)$ lie in $F(y)$ and hence $R(t)\in F(y)[t]$. Clearly $R(x)=0$.  Now I only have to prove $R(t)$ is actually the minimal polynomial of $x$ over $F(y)$. I believe the next step is to obtain a contradiction that $R(t)$ being reducible can lead to $f,g$ being not coprime, but I can't figure out how to do that.  P.S. A hint is preferred over a full answer.


I was discussing this at work with a colleague today, which form (or both) is grammatically correct when referring to dates? "on the 5th of November" vs "on the 5th November"

A friend of mine, native EN speaker, told me that the following is correct written like this:      We met on the 1st of June.   Is that really true? I cannot see any reference that these are used in written text.


i've been looking over possible duplicates of this question and haven't found one yet.  so, using Wikipedia as the textual source:   The Principle of Relativity – The laws by which the states of physical systems undergo change are not affected, whether these changes of state be referred to the one or the other of two systems in uniform translatory motion relative to each other. The Principle of Invariant Light Speed – "... light is always propagated in empty space with a definite velocity [speed] $c$ which is independent of the state of motion of the emitting body". That is, light in vacuum propagates with the speed $c$ (a fixed constant, independent of direction) in at least one system of inertial coordinates (the "stationary system"), regardless of the state of motion of the light source.   so, is it not the case that observers in "one or the other of two systems in uniform translatory motion relative to each other" have the very same $\epsilon_0$ and $\mu_0$?  if they don't, that contradicts the premise of the 1st Postulate.  i just cannot see how the 2nd Postulate is not redundant.  it comes about directly from the 1st and from the known laws of physics preceding SR.  you see, it's not just about light and $c$ and $\epsilon_0$ and $\mu_0$.  it's all the other laws of physics and the parameters that come with these laws.  i.e. every inertial frame of reference has the same Planck's constant, $\hbar$, same gravitational constant, $G$, and same elementary charge $e$.  if the frames of reference didn't have the same values, such would violate the 1st Postulate, but that wouldn't violate the 2nd Postulate since that's restricted to $c$.

Einstein's two postulates of special relativity are as follows,     1. The principle of relativity: The laws of physics are the same in all inertial   systems. There is no way to detect absolute motion, and no preferred   inertial system exists.      2. The constancy of the speed of light: Observers in all inertial systems mea-   sure the same value for the speed of light in a vacuum.   Now for an exercise in my book, I am requested the following:     'Explain why Einstein argued that the constancy of the   speed of light (postulate 2) actually follows from the   principle of relativity (postulate 1).'   I have been trying to figure this out for a very long time now with no luck. I thought of identifying a physical law that if not the same in two different inertial systems leads to a contradiction, but I can't think of anything. Could you push me in the right direction?


I tried upgrading pip3 using su -c 'pip3 install' --upgrade pip' because I got errors and it failed when trying to upgrade it as a normal user.  This removed the pre-installed pip from /usr/bin and dumped it in /tmp, replacing it with a system wide installation of pip which is only accessible by root. I haven't tried to uninstall this new pip because I suspect it would lead to more problems.  Since I still have the old pre-installed pip in /tmp, how do I get back the pre-installed pip using this executable that is still in /tmp?  Location of pip in /tmp:  /tmp/pip-ufkfr3th-uninstall └── usr     └── bin         └── pip

Is there a command to recover/undelete deleted files by rm?  $ rm -rf /path/to/myfile   How can I recover myfile? If there is such a tool how can I use it?


we have five different meanings for canary:   having the color of a canary; of a light to moderate yellow any of several small Old World finches a female singer a moderate yellow with a greenish tinge someone acting as an informer or decoy for the police   I have a sixth:   a fail bird that dies as an warning indicator   My question is: What is a synonym for canary? (being a fail bird that dies as an warning indicator)

Is there a single word to describe the canary in the phrase "Canary in a coalmine"?  The best I can come up with is sentinel, but I'm nearly positive there's a more precise option.  Edit: To clarify I'm not looking for words that describe the canary but rather for a word the encapsulates the entire phrase.  That is, I don't want to finish the phrase "the canary is a ...".  I do want to finish the phrase "$PERSON was a ..." where the blank implies as many of the attributes of the proverbial canary as possible (e.g. going down the dangerous road first, warning those that follow, connotations of captivity, &c).  I'm reluctant to use the phrase, or "canary" as it strikes me too colloquial/lighthearted for the work at hand.    @senex suggestion of bellwether and @bib suggestion of tocsin are closest to what I'm looking for thusfar.


Here is my code, i cannot figure out the difference between these two lists of list:   cow = 1 column = 1 size = 3 board1=[[0,0,0],[0,0,0],[0,0,0]] print board1 board2=[[0] * size] * size print board2  if board1==board2: print 'same'  board1[cow][column] =1 board2[1][2] =1 print "Board 1 is :", board1 print "Board 2 is :", board2   Result:  [[0, 0, 0], [0, 0, 0], [0, 0, 0]] [[0, 0, 0], [0, 0, 0], [0, 0, 0]] same Board 1 is : [[0, 0, 0], [0, 1, 0], [0, 0, 0]] Board 2 is : [[0, 1, 0], [0, 1, 0], [0, 1, 0]]

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


It's pretty obvious why it doesn't work using the sequence algorithms.  So the way I thought of it:(n is the number of vertices)  at n = 1: you get 0, which is the graph of just one vertex  at n =2: you get 1, 0 which is two vertices with one having a degree of 1, but the other vertex has no edges so this is impossible.  this continues on for n greater than 2 as well. Not sure if this is enough to answer the question.  Edit: possible new solution, there are n possible degrees for n vertices which is impossible when $n\geq2$

Any help would be appreciated.  If $n$ is a natural number $\ge 2$ how do I prove that any graph with $n$ vertices has at least two vertices of the same degree?


The PDF of a Beta distribution is $$ f_X(x) = {{x^{a-1}(1-x)^{b-1}}\over {B(a,b)}}  $$ and CDF $$ F_X(x) =  I_x(a,b) $$ The PDF of a uniform distribution is $$ f_Y(y) =  {1 \over {b-a}} \space for \space  x \in [a,b] $$ and CDF $$ { x - a} \over {b - a} $$ I've know that if X and Y are two independent, continuous random variables, described by probability density functions above of $f_X(x)$ and $f_Y(x)$ then probability density function of $Z = XY$ is $$  f_Z(z) = \int_\infty^\infty f_X(x)f_Y({z\over x}){1\over abs(x)}dx  $$ but I'm struggling with the algebra to get  from this to the PDF and the CDF of the joint distribution. I'm using the uniform distribution between 0 and 1.

I am looking at trigger efficiencies, meaning that I have some device that fires on $k$ out of $n$ events. In the end I am interested in some estimate of the efficiency $\epsilon$ which is the probability to fire on a randomly given event. Using a Bayesian approach with a uniform prior over $[0,1]$ I can model the probability distribution for $\epsilon$ as a Beta distribution $\beta(\epsilon; k+1, n-k+1)$.  Now comes the question: I calculate the efficiency using "bootstrapping" which means that the final trigger efficiency is the product of two trigger efficiencies, both of which can be modelled as Beta distributions.  How can I calculate this product of the two Beta PDFs for large values of $k_{1,2}$ and $n_{1,2}$ efficiently? Is there a closed form of the product (AFAIK not)? At the moment I am doing this numerically, but this is rather slow.   has the answer how to evaluate integrals of the Beta distribution for large argument values, but this does not help here.  I hope my question is clear and not completely stupid...


I looked at a chat where people said there were about 730ish steps along the way, but I was wondering if they counted the steps in each row as one or counted all individual steps, because in some cases there won't be one step per stair, there can be 2-4 steps where the one whole stair is. Can anyone clarify how many steps there are as every single stone slab on it's own as a step?

The title says it all.  It is mentioned several times that there are 7000 steps on the path to High Hrothgar. Are there actually 7000 steps or are the NPCs exaggerating?


I am very new to Ubuntu and to rails. I tried to do a bundle install after installing rails through rvm, but I had an error back with the openssl. I looked online for a solution and I uninstalled the openssl with this command sudo apt-get remove --purge openssl After that chrome and software center disappeared, I am not able to even install the software center and I have this message back when I try to do so. Package software-center is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'software-center' has no installation candidate  How can I fix it?  Thank you

What does the above Error mean? What is an installation candidate?  I was trying to do  sudo apt-get install munin-memcached     and I get this message:  Reading package lists... Done Building dependency tree        Reading state information... Done Package munin-memcached is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package munin-memcached has no installation candidate   I googled for the problem and someone said to do a apt-get upgrade but it still did not solve my problem.


I have a form that is being inserted inside of a node edit form and the inserted form is given a custom submit handler. The inserted form's submit button is defined as follows:     $form['decision_select']['update'] = [       '#type' => 'submit',       '#value' => $this->t('Select Segment Set'),       '#submit' => [[$this, 'updateSegmentSet']],       '#limit_validation_errors' => [],       '#ajax' => [         'callback' => [$this, 'updateSegmentSetAjax'],         'wrapper' => $wrapper_id,       ],     ];  However, when I click 'Select Segment Set' the entire node form is submitted to the backend (I've verified this by printing the request/route objects sent to the backend). Is there any way to press that submit button and have only the inserted form sent to the backend along with this custom submit handler? The idea is to have this inserted form filled with values given to it via ajax before the node form is ever submitted to save the node.

I'm porting a module that currently works with Blocks/BlockForms to Paragraphs/NodeForms. I'm inserting an embedded form inside a Paragraph inside a Node Edit page using a hook_field_widget_entity_reference_paragraphs_form_alter. The general structure where the form gets inserted is: $form['field']['widget'][0]['settings'][form here]  After this the form displays as expected on the node edit page. The inserted form goes through a number of #process steps. The element in question is a select form that when the button underneath it is pressed, is supposed to retrieve some data via a custom submit handler and place it on the page with ajax:  The array for this element looks like this:  You can see the custom submit handler that is supposed to fire when 'Select Segment Set' is pressed After debugging, I've found that the entire NodeForm appears to be submitted to the backend, and the only handler that is found is from some other field that uses ajax. In short 'updateSegmentSet' is never discovered as a submit handler. When I debug the original module based on block/blockforms, I do see the correct submit handler being discovered. Now in the latter case, of course a blockForm is submitted to the back end with the correct plugin. Given that this is basically a form within a form within a form, is there something special I have to do to get the custom submit handler to run? I've read a few things online e.g. the 'settings' key and '#tree' = true. EDIT The Ajax property looks like this:       '#ajax' => [         'callback' => [$this, 'updateSegmentSetAjax'],         'wrapper' => $wrapper_id,       ],    public function updateSegmentSetAjax(array &$form, FormStateInterface $form_state) {     $button = $form_state->getTriggeringElement();     // Go one level up in the form, to the widgets container.     return NestedArray::getValue($form, array_slice($button['#array_parents'], 0, -2));   }  As best I can tell, this is never called either.


In $\oplus$, '+' sign is there inside a circle. I want to put similarly a '+' sing inside a square. How is it possible in latex?

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


I have a large group playing DnD. Some players are doing well with it, others not so much.    A "not so much" player is the Druid. he runs through encounters setting fire to everything, including the forest -- which seems to not be the style for a Druid.    I'm struggling creatively (writer's block as it were) to come up with a method of stripping the player's Druidic powers, and then working out some kind of challenge system that works in-line with Druid teachings for him to redeem himself and restore his powers.   What consequences are for a Druid not acting like a Druid?  What training (or remedial training) is required to be a Druid?  Where does a Druid's power come from and how can that link be severed?

I have a player who created a Druid and is mostly playing like a barbarian in combat and like a rogue the rest of the time.  This means he kills animals, does not care for plants, does not use his magic even when someone could use Cure Wounds... (although that last one is certainly okay for a neutral character.)  And when in the presence of an NPC that looks rich, multiple attempts to steal as much as possible from it (like a level 1 character should steal from a cloud giant...)  What would you do in this situation? I'm playing 5e and am allowing all extensions so the characters can multi-class. On my end, I was thinking to force him to choose another class once at level 2. Would that be wise? I think that would be much more likely to teach him a lesson rather than letting him continue as this barbarian/rogue under the disguise of a druid...    To answer the first comment fully:  PHB p64. under Power of Nature     Druids revere nature above all.   So being the first to kill everything, including animals, seems quite contradictory to the class already... (were he evil, I could understand that he like monstrosities, and not "regular" animals, but that is not the case here.)  PHB p64. under Preserve The Balance  Already the title sounds like a Druid seeking just gold and gems and other riches is not going to help much in preserving the balance...     [...] Druids oppose cults of Elemental Evil and others who promote to the exclusion of others.   Gold and gems could be viewed as promoting the Earth Elemental.     Druids are also concerned with the delicate ecological balance that sustains plant and animal life, and the need for civilized folk to live in harmony with nature, not in opposition to it.   This re-enforces my first excerpt.  PHB p65. under Creating A Druid     When making a druid, consider why your character has such a close bond with nature.   I will say, Barbarian are considered to be close to nature as well... so a barbaric fighting aspect may not be too far off from a Druid's devotion. Plus Druids may fight like Barbarian when their territory is at risk.    Now... looking at the Circle of the Moon, I guess I could force him to join that circle rather than the other one made of mystics and sages.


I removed the /bin instead of ~/bin :(  My laptop no longer boots up! It has no DVD or CD drive!  How can I restore the OS X?  It is MacBook Pro OS X 10.8, SSD 128GB.

I've deleted a system file from my Mac and need to get it back.  System files can include:   hidden files in the root of / - especially unix files in /private  /System files /Library files /Applications files that ship with the core OS   System files are not any app, user files or files that can be regenerated by a known sequence such as cache files, Spotlight index files, etc…    Canonical question and answer for .


Using: QGIS version 2.12.0-Lyon. No Add-on available.  Problem: I do not know where to start after opening the Python console with regards to writing a script that creates a new layer per value queried from a field within QGIS Desktop. I have experience with arcpy and am trying to start with a basic scripted action to learn Python for QGIS.  At the moment I can list all the attributes found in the "active" layer see below:      lyr = iface.activeLayer()      features = lyr.getFeatures()      for feat in features:         attrs = feat.attributes()         print attrs[1]   However, I would like to iterate this and create a new memory layer (i.e. only available whilst the project is open) per feature per attribute creating a new layer where a query is set to equal that attribute (i.e. Name = feat[0])  Can anyone assist in building a template script solution?  This can be partly completed without using Python by using the "Split Vector Layer" tool. However, this tool will create a folder of shapefiles and not "in memory" layers.

Is there a way, using Python, to duplicate a layer in QGIS as many times as the single occurrences of a variable contained in a field and with a filter applied on the duplicated layer based on the variable itself?   An example: I have layer0 with a field0 that contains var1, var2, var3, etc. I would like the layer0 duplicated to layer1, layer2, layer3 etc. so that layer1 has a filter where field0 = var1, layer2 has a filter where field0 = var2, etc.  The idea is similar to the LayersByField plugin but instead of creating a new layer for each occurrence of a variable I wish to just duplicate the "master" layer (so to avoid unnecessary files on disk)


I have a machine which all its system drive files e.g /etc/* /lib/* /home/* where moved to a storage system by mistake. Now I moved them back to their original places but I don't know how to set the permissions to the original one?

I accidently ran  sudo chmod 755 -R /   instead of  sudo chmod 755 -R ./   I stopped it after few seconds, but now there is some problems such as  sudo: must be setuid root   How can I revert permissions back?


So I have npm and installed gulp globally. gulp.cmd is available under %Appdata%/npm and it had added the NODE_PATH user variable.  When I type in gulp in my command prompt, it returns 'gulp' is not recognized as an internal or external command. But it is! It is in %Appdata%/npm.  Why is that? I've checked and the links are valid and I can execute gulp like so %node_path%/gulp

Questions about    setting environment variables the PATH   are very common here, and in most cases the answers are very similar to each other. In the future it would be nice to have a good Q/A for this.  So the question is: What are environment variables, like the executable PATH, and how can I change and use them on major operating systems?  A good answer would include a simple explanation of what environment variables and especially PATH mean to the OS, as well as simple guidelines on how to set and read them accordingly.


I am trying to validate a mobile number of 11 digit , where the 1st 3 digit will be 019 , 018 , 017 , 016 . How can I check this that the first 3 digit will be fall among the four criteria??  I can validate if the number is a character or is it less than 11 digit using the code bellow.Now the problem is I want to check If the 1st 3 digit fall into the four criteria( 019 , 018 , 017 , 016)   var phoneno = /^\d{11}$/;     if(inputtxt.value.match(phoneno))     {         return true;     }

I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant.


I don't know how, but there's a . I don't have to explain how incredibly handy that would be.  Unfortunately, Stack Exchange is unable to get the images from that site, not even by direct URL, so I have to create a file like an idiot every time.  It appears like this is just due to Stack Exchange , could this feature please be added?

I've tried to find other questions covering this, but (surprisingly) I did not find any.  When I want to add a screenshot to a post, as far I know the only way to do it is to save it as a file and then upload the file, using Stack Overflow's image hosting. OK, much better than finding a hosting site yourself, but sometimes I wish I could just paste the image from the clipboard.  It's not as straightforward as it may seem, I know. , and it needs a Java applet to get it done.


What would you call a person who always want to learn new things (new skills/informations)

Is there a term that means "a person who enjoys learning"? This term might be used to describe someone who:   Is a self-motivated learner. Is curious, wants to understand many things.   I understand the term "philosopher" might be a good fit, in terms of its root words, however, the general population has an inconsistent understanding of this term, so I am looking for a more precise term.


I'm writing a bash script that modifies a program, then adds an icon to the unity launcher. Although I've created the .desktop file in /usr/share/applications, I can't see a way to programmatically add the shortcut to the launcher.

I am customizing an Ubuntu 14.04 Live CD with UCK (Ubuntu Customization Kit). The program gives you a chroot environment in a terminal to make changes.   I want to add and remove what programs appear on the dock.  I'm not sure if this can be accomplished by modifying the .desktop file?  How can this be done using the terminal?


I recently needed some of the really useful nirsoft tools.  Many are command line tools and they need a location in the path to run from.  I dumped them somewhere to get things done but I want to know if there is an official place in the file system for these tools.   I do not think they should be directly in "Program Files" nor do I like the proliferation of application specific locations because they bloat the path environment variable.  Its hard enough to read as it is.  I am considering a top level "bin" directory or "tools" but I fear it might offend some MS rule.  suggestions?

On the Windows platform, most large applications come with their own installer which sets up folders under C:\Program Files, possibly some other places, and perhaps adding some registry keys, etc.  But there's still quite a few tools around that consist of just an .exe or maybe also a README and a .dll or two.  How should I install such tools? Directly in C:\Program Files? All in one subfolder under C:\Program Files? Somewhere under C:\Users\Me? Somewhere totally different?  Or maybe different approaches for the tools with just an .exe to those that also have other files, or maybe only the ones with .dlls need to be treated differenty ...  Is there any standard accepted way to do this? A "best practice"? If the answer depends on the Windows version, I'm using Windows 7.  In particular, what might strike people as the obvious answer seems to have a catch:  I had tried to manually create new subfolders under C:\Program Files. In fact I thought I had done so before, but Windows puts up a dialog Destination Folder Access Denied. This caused me to think twice rather than just blindly click Continue.      On the assumption that greater minds than mine have come up against this many times over the years I'd like to ask the community if some kind of "best practice" has come to be accepted.


Google Chrome is set being my default browser in System Settings, Details. And is also set as default browser within Google Chrome 46.0.2490.80 (64-bit) I reboot three or four times a day and Google constantly asks whether it should be the default. Bug?

Since the Ubuntu 15.10 upgrade, google-chrome-stable keeps asking if it should be set as default browser, even though it already is. I tried to reinstall it, but that didn't help. Any ideas?


So i have downloaded an object, when i open it on blender, it shows gray object (no texture). There is a file called "character texture.psd", how do i apply the .psd file on my object? I'm new on blender, glad you'll help.

For the first time I'm working with an artist who is going to be creating the textures for the models I create in Blender.  Up till now I had been building the models and the texturing them myself using pre-built textures from websites.  My question is: What is the easiest process for me to apply the textures our artist creates to my model?  Should I give the artist the UV Map from my model, or should I just get textures from the artist and fit them to the UV Map?  Basically I have no idea how this process works in a professional environment.


The full question is: Let $K \subseteq \mathbb{C}$ be a cyclic exntesion of $\mathbb{Q}$ of degree 4. Prove that $i \notin K$.  I was thinking that since $K$ over $\mathbb{Q}$ is finite (has degree 4) and is separable (since it's Galois), by the Primitive Element Theorem, $K = \mathbb{Q}(\alpha)$ for some $\alpha \notin \mathbb{Q}$. So if I show that $i \neq \alpha$ then the statement holds. So suppose $i = \alpha$. Then $K = \mathbb{Q}(i)$. However, the degree of $\mathbb{Q}(i)$ over $\mathbb{Q}$ is not equal to 4. So $i \neq \alpha$.   Does this work? If not, please explain why/any ideas you may have. Thank you!

Suppose $K$ is an extension of $\mathbb{Q}$ in $\mathbb{C}$, where $Gal(K/\mathbb{Q})$ is cyclic of order 4. Show that $i\notin K$.   ($i$ is the imaginary number $i^2=-1$.)  My Galois theory is quite weak, hope someone can check if my attempt is correct.    My attempt:  Suppose to the contrary $i\in K$. Let $\sigma\in Gal(K/\mathbb{Q})$.  Note that $\sigma (i)\sigma(i)=\sigma(i^2)=\sigma(-1)=-1$ since $\sigma$ fixes $\mathbb{Q}$.  This means that $\sigma(i)=i$ or $\sigma(i)=-i$. The first case is ruled out since $\sigma$ only fixes $\mathbb{Q}$.  So $\sigma(i)=-i$. This means that $\sigma(a+bi)=a-bi$, so $\sigma$ is effectively complex conjugation, which has order 2.   Since $\sigma$ was arbitrary, this contradicts that $Gal(K/\mathbb{Q})$ has an element of order 4.    Is this ok?  Thanks.  Update: Now I see that my argument is clearly flawed. What would be the correct proof?


This is an excercise from Spivak's Calculus. Show that if $x^n=y^n$ and $n$ is odd, then $x=y$. Hint: first explain why it suffices to consider only the case x and y greater than 0, then show that x smaller than y or greater y are both impossible.  I try to prove this by using induction. The base case $n=1$ is correct. Assume that $n=2k+1$ is true, prove that $n=2k+3$ is also true. But now I don't know how to proceed.

Here, we suppose that $x,y\in\mathbb{R}$ and that $x^n=y^n$, where $n$ is odd. I want to prove that $x=y$.  Maybe we can use that $x^n-y^n=(x-y)(x^{n-1}+x^{n-2}y+...+xy^{n-2}+y^{n-1})$  So, it suffices to show that if $x^n=y^n$ then $x^{n-1}+x^{n-2}y+...+xy^{n-2}+y^{n-1}\neq 0$  Any hint?


I properly(i think) installed ubuntu along side with windows 8.1 which is my computers first OS.  I have done the "Try ubuntu without installing" option and then trying to install and it tells me that ubuntu is already installed.    The problem is that I cannot get ubuntu to boot.  My computer jumps straight to Windows 8.1 everytime.  I have enable legacy booting, and tried everything i can think of.  Any suggestions?

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


If $n > 0$, then prove the following by using induction: $$133|(11^{n+2} + 12^{2n+1}).$$

Problem taken from a  on mathematical induction by Gerardo Con Diaz. Although it doesn't look like anything special, I have spent a considerable amount of time trying to crack this, with no luck. Most likely, due to the late hour, I am missing something very trivial here.     Prove that for any integer $n$, the number $11^{n+1}+12^{2n-1}$ is divisible by $133$.   I have tried multiplying through by $12$ and rearranging, but like I said with meager results. I arrived at $11^{n+2}+12^{2n+1}$ which satisfies the induction hypothesis for LHS, but for the RHS I got stuck at $12 \times 133m-11^{n+1}-11^{n+3}$ or $12^2 \times 133m-12 \times11^{n+1}-11^{n+3}$ and several other combinations none of which would let me factor out $133$.


I am thinking about entering the world of money and what should a first time investor should do to get a idea of what they are doing?

I am young, just started my career, and looking to begin investing so I can make my money work for me. I'm still living like I did in college (occasional purchase on myself, but most of it goes into savings) and I would like to take the extra money and invest it.   What would you suggest are the best options for me to begin? I was considering getting a personal investor [a financial advisor] for perhaps a year or so, but I've heard that they really are not worth the money. I wanted to get the input of the great minds here.


I want regx for following condition      1.Combination of Letters and Digits should accept.      2.Combination of Letters and symbols should accept.      3.Only Letters should accept.      4.Only digits should not accept.      5.Only Symbols should not accept.      6.Combination of letters,digits,symbols should accept.   I am trying like this:  /^([a-zA-Z]+\s*)*[a-zA-Z]+$/   What is wrong.

I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them?


I have a simple question for the gurus... How bad is this?    A few days ago I was using my laptop and next day I have this on the screen. So I installed the HDD on my desktop to see if I can get all my stuff from the disk, but I can't. This is the message when I try to boot with this HDD.

Upon trying to upgrade from 10.10 to 11.04 all seemed to go well until the restart. This error message is what comes up:  Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)   How do we fix that?


I am a U.S. citizen and will be laying over in Paris for 23 hours.  I want to go into Paris and look around.  Will I need to have a visa or something to do so?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


I'm getting no core dumps, and  says the problem might be that my kernel might be configured with CONFIG_COREDUMP, how do I find out if it is true?  I'm on Mint 17.3 (uname -a: Linux laptop 3.19.0-32-generic #37~14.04.1-Ubuntu SMP Thu Oct 22 09:41:40 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux).

I'm pretty sure that all Red Hat and Debian based distributions follow the convention of shipping the kernel configuration in /boot/config-*, but what of other distributions?  Or, if this convention is extremely common, which distributions don't follow it?


What is the difference between these 2 sentences?  1. Audi has grown to compete with such cars as Lamborghini. 2. Audi has grown to compete with cars such as Lamborghini.    To me, both sentences seem to mean the same. Is there any unapparent difference?

I read a lot of English books, and I have noticed that when authors need to list examples of something, they tend to use "such things as" rather than "things such as", although they both sound correct. The latter even seems to have a better structure, since it doesn't split the "such as" (a phrase commonly used to indicate examples).   Is there any subtle difference in meaning between the two? Why is the former preferred?  For example:     Eventually, the device becomes stable, but its final state is unpredictable since it is based on such things as construction differences and thermal noise.


Let $f: S^1 \subset \mathbb{R}^2 \to \mathbb{R}$ be a continuous function on the unit circle $S^1$. Show that there is $x \in S^1$ s.t. $f(x)=f(-x)$  Intuitively this is quite clear since I can imagine if this does not hold, we should have sort of a spiral that is not continuous at one point. But I'm not sure how to show this exactly. Any ideas?

Let $S^{1} := \lbrace(\cos\alpha, \sin\alpha) \subset \mathbb{R}^{2} | \alpha \in \mathbb{R}\rbrace$ be the circumference of radius $1$ and $f: S^{1} \to \mathbb{R}$ a continuous function. Prove that there exist two points diametrically opposed at which $f$ assumes the same value.  My idea for the solution: Define $\varphi: S^{1} \to \mathbb{R}$ as$$\varphi(\cos\alpha, \sin\alpha) = f(\cos\alpha, \sin\alpha) - f(-\cos\alpha, -\sin\alpha).$$ If $f(\cos\alpha, \sin\alpha) = f(-\cos\alpha, -\sin\alpha)$ for all $\alpha \in \mathbb{R}$, the result follows. Otherwise, there exist $\alpha_{1},\alpha_{2}$ such that $$f(\cos\alpha_{1}, \sin\alpha_{1}) - f(-\cos\alpha_{1}, -\sin\alpha_{1}) > 0$$ and $$f(\cos\alpha_{2}, \sin\alpha_{2}) - f(-\cos\alpha_{2}, -\sin\alpha_{2}) < 0.$$ Applying the intermediate value theorem, we prove the result. Is this a correct idea? I appreciate your commentd. Thanks!


I want to know if I could install ubuntu touch on a Samsung Galaxy Core Plus.  I have not tried anything yet, I am looking into buying this phone but I would like to know if I can get ubuntu on it first.

With the announcement of the Ubuntu Phone OS I'd like to know what phone (and tablet) models are supported at this time.  Note from foss & Oli: We are making this the master question for all future "Will this work on <insert random tablet/phone/device here>?!" questions


Considering A as a unique factorization domain, we must show that every prime ideal of A is generated by a set of prime elements. I was able to do it for a principal prime ideal, but I couldn't do it for other cases.

Fulton, "Algebraic Curves," Exercise 1.39(a):     Let $R$ be a UFD, and $P = (t)$ a principal, proper, prime ideal.    Show there is no prime ideal $Q$ with $0 \subset Q \subset P$.   After being stumped for some time, I came up with the following proof while attending a concert (my ears are still ringing an hour later):     Suppose there is such an ideal.  Take some $0 \neq q \in Q$.  Since $Q \subset P$, $q = rt$ for some $r \in R$.  Since $Q$ is prime, and $t \not \in Q$ by assumption, we must have $r \in Q$.  Applying the preceding to $r$ instead of $q$, we have $r = r't$ for some $r' \in Q$.  So $q = rt = (r't)t = r't^2$.  Proceeding along these lines, $q$ is divisible by $t^n$ for all $n \geq 0$.  Notice that $t$ is irreducible, since $P = (t)$ is prime.  Now, what possible factorization into irreducibles could $q$ have?   So far as I can tell, this seems to work, but it also seems exceedingly silly.  What's the "right" way to prove this?


How can I overwrite the style of my Instagram Feed? I want the the following applied, but don't know where to set my css, it doesn't work neither in the header or the footer of my page. .Header{display:none;} .PrimaryCTA {display:none;} .PrimaryCTA {display:none;} .Feedback  {display:none;}

Is it possible to change styles of a div that resides inside an iframe on the page using CSS only?


I just completed reading the lotr books for the 3rd time a couple of weeks back and this entire issue with Arwen and her immortality is bugging me way more than it should! I feel like I really need to get it off my chest.  So Arwen's marriage to Aragon is only the 3rd time in all of tolkien history in which an Elf has wed a Man, the other 2 being Luthien & Beren (married under extreme circumstances, more of a one-time basis) and Tuor & Idril (married without much difficulty with the approval of Idril's father, King Turgon). As you can see there is not much previous references to go on, which leads me to my first question:   Could Arwen simply have married Aragon without having to give up her immortality? If not why couldn't she do so? (Idril married Tuor without giving it up)   I understand that being Half-Elven she had the choice to choose between being an Elf or a mortal , much like her father and Elros. But wouldn't she have solved a huge 'problem' by marrying Aragon whilst still 'choosing' to be an immortal Elf? I can't find any text that says she has to give up her immortality to marry Aragon. In fact I can't find any text that says an Elf must relinquish their immortality to marry a mortal (I'd be more than happy to be corrected on this point)  In the books, Arwen clearly loves her father dearly almost as much as she loves Aragon and she is torn between the two. Which makes me wonder for my 2nd question:   Would it be possible for her to marry Aragon, live together as a happily married couple till his days on middle-earth is up before departing for the Undying Lands to rejoin her people and Elrond?   I say this because in the Tales Of Aragon And Arwen, even on his deathbed Aragon seems to confirm the fact that Arwen still had a choice     '"I speak no comfort to you, for there is no comfort for such pain within the circles of the world. The uttermost choice is before you: to repent and go to the Havens and bear away into the West the memory of our days together that shall there be evergreen but never more than memory; or else to abide the Doom of Men." Appendix A, RoTK   Correct me if I am interpretting it wrongly but it seems to me that Arwen still has the "uttermost choice" before her to sail to Valinor to reunite with her father.  This would have been made even easier by the fact that upon learning of Aragon's death, Legolas built a ship and sailed to Valinor together with Gimli. I'm assuming that Arwen could have joined the both of them on this final journey?

I am sure Elrond is half-elven, so Arwen is too.  I recall something saying Argorn was half-elven as well.  Shouldn't half-elves not have to become mortal to marry each other?


I'm having a big problem with the bezier curves in Blender. Im trying to fill up the curves, but i can't. I have already saw some videos from youtube, telling that I have to clic on the 2D button.    But when i clic on the 2D button, this is what it happens.    I will really appreciate any help.  Thank you very much.

I'm having a big problem with the bezier curves in Blender. I'm trying to fill up the curves, but I can't. I have already seen some videos from YouTube, that say that I have to click on the 2D button.    But when i click on the 2D button, this is what it happens.    I thought it was a problem with the camera, but:    What am I doing wrong?


I'd like to add, next to bluetooth, wifi indicator, etc. another button that would bring conky to the front of opened windows.  Any tips? Googling didn't really help me much, only instructions how to set up conky.  My Ubuntu version is 18.04 my desktop enviroment is GNOME3.

This is more of a asking for direction. What are the means of developing programs that can add something to the Ubuntu top bar?  Let's say I want to make a program that shows the network traffic on the topbar. I'm focusing on GNOME. What should I learn?  p.s. I am not a newbie to programming and bash.


I have this problem with Comodo:     (Reading database ... 143450 files and directories currently installed.) Preparing to unpack cav-linux_x64.deb ... Unpacking cav-linux (1.1.268025-1) over (1.1.268025-1) ... Uninstallation succeed! dpkg: dependency problems prevent configuration of cav-linux:  cav-linux depends on libssl0.9.8 (>= 0.9.8m-1); however:   Package libssl0.9.8 is not installed. dpkg: error processing package cav-linux (--install):  dependency problems - leaving unconfigured Errors were encountered while processing:  cav-linux   Is any simple solution or is better to wait for Comodo updates that fit Ubuntu 18.04 LTS 64-bit.  Thanks

What does the above Error mean? What is an installation candidate?  I was trying to do  sudo apt-get install munin-memcached     and I get this message:  Reading package lists... Done Building dependency tree        Reading state information... Done Package munin-memcached is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package munin-memcached has no installation candidate   I googled for the problem and someone said to do a apt-get upgrade but it still did not solve my problem.


I've encountered a number of problems in my coursework that require me to find $\lim_{x\rightarrow\infty}x^{\frac{1}{x}}$, the solutions to which apply the following identity:  $$\lim_{x\rightarrow\infty}e^\frac{\ln{x}}{x}=e^{\lim_{x\rightarrow\infty}\frac{\ln{x}}{x}}$$  What principle allows us to move the limit operator into the exponent?  Are there any conditions (aside from the limit not existing) under which this is not allowed?

I've seen some limit problems where you can do this: $$ \lim_{x \to \infty} \exp\left({g(x)}\right) = \exp \left( \lim_{x \to \infty }g(x)\right) . $$ So, I've tried to generalize the result as: $$ \lim_{x \to \infty} f(g(x)) = f \left( \lim_{x \to \infty }g(x) \right) $$ and I was just wondering if the result above is actually true, and on what conditions? Perhaps someone can point me to a theorem.


Fanatic badge description says "visit site 100 days in a row", is this applicable to StackExchange android app as well ?, most of the time i check stackoverflow only with app.

If I do any of the below, which would normally constitute "activity" on any Stack Exchange site (including mobile):   View my profile Vote on any question or comment Visit one or more questions   ...then Stack Exchange considers me to have "visited" the site.  If I do any of the below on the mobile app:   Vote on any question or comment Visit one or more questions   ...then Stack Exchange does not consider me to have visited the site.  If one wants the app to have feature parity with the mobile site, then shouldn't my participation within the app also count towards the Enthusiast/Fanatic badge?


How can I show that $\arctan (x) + \arctan(1/x) =\frac{\pi}{2}$?   I tried to let $x = \tan(u)$. Then   $$ \arctan(\tan(u)) + \arctan(\tan(\frac{\pi}{2} - x)) = \frac{\pi}{2}$$  but it does not seem useful.      I'd appreciate most a proof that gives intuition and / or uses geometric   insight.

In my textbook it asks for me to:  Prove that there is no constant $C$ such that $\text{arccot}(x) - \text{arctan}(\frac{1}{x}) = C $ for all $x \ne 0$. Explain why this does not violate the zero-derivative theorem.  But I believe I have found such a $C$, i.e. $C =0$! I even asked WolframAlpha () which corroborates my answer.    This question appears in Apostol's Calculus Volume I, Second Edition: Exersize 6.22-11b  Edit: Mathematica's definition of arccot is different from the one in my textbook. Apostol's arccot maps a real number into $(0, \pi)$ while Mathematica's maps a real number into $(-\pi/2, \pi/2)$ Here they are super-imposed:


How I can to draw using GDAL in python or c a polygon shapefile shape.shp with a GeoTIFF as background background.tiff file?  Both files are in the same projection.  The result could be a PNG, JPEG or whatever.  To clarify I'm going to put screen shoots of the done with QGIS. First one is the shapefile, second the GeoTIFF, and finally the union.

I am using gdal_rasterize to create a raster of a huge file containing polygons. I managed to generate the raster file with the right color and with the minimum size to tile it after with the gdal2tile.  gdal_rasterize -of GTiff -co COMPRESS=DEFLATE  -b 1 -b 2 -b 3 -burn 136-burn 46 -burn 17 -co PREDICTOR=2  -co ZLEVEL=9 -ot Byte  -a_nodata 255  -a Niveau  -ts 500000 500000  -l layer W:/layer.shp W:/layer.tif   Tile will be used to overlay Google Maps so the polygon must be transparent.  Has anybody experimented with this usage of gdal_rasterize and succeeded in setting the opacity of the output raster?


I have a question. If a normed function, that is to say  $$ \int_{-\infty}^{\infty}|f(x)|^2dx<\infty~~~\text{(summable square function)}$$  then,   $$\underset{\begin{array}{c} x\rightarrow+\infty\\ x\rightarrow-\infty \end{array}}{lim}f(x)=0$$  It is true, why?  thanks

I have difficulty to demonstrate this:  $$ \int_{-\infty}^{\infty}|f(x)|^2dx<\infty~~~\text{(summable square function)}$$  then,   $$\lim_{|x|\rightarrow\infty }f(x)=0$$  thank you.


Prove that for all positive real $a,b,c$, we have  $$(a^2+2)(b^2+2)(c^2+2) \geq 9(ab+bc+ca).$$  Because of the term $a^2+2$, this motiveates me to substitute $a=\sqrt{2}\tan A, b=\sqrt{2}\tan B, c=\sqrt{2}\tan C$ and the fact that $1+\tan^2x=\sec^2x$, then the desired inequality becomes $$2^2\sec^2 A\sec^2 B \sec^2 C\geq 3^2(\tan A\tan C + \tan B\tan C + \tan C \tan A).$$  But then I was stuck and couldn't move further, please helps.

Let $a$, $b$, $c$ be nonnegative real numbers.   Prove $(a^{2}+2)(b^{2}+2)(c^{2}+2)\geq 9(ab+bc+ca)$.


I have got a login page and I want to align form element to the center of the page.   .signininp {   border-radius: 20px;   width: 20%;   margin-top: 10px;   padding: 5px; } <form>   <input class="signininp" type="input" name="email">
   <input class="signininp" type="input" name="pass">
   <input class="signininp" type="submit" name="submit" value="Giriş Yap"> </form>

How can I horizontally center a
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 using CSS?

Foo foo


Although I could be wrong, I suspect the question in my title will be answered in the negative.  Let $f:D \to \mathbb{C}$, where $D$ is the open unit disk. Assume that $\forall k \in \mathbb{Z}^+\left[f(\frac1{2k})=f(\frac1{2k+1})=\frac1{2k}\right].$ Assume further that $f$ is analytic on $D$. I will try to derive a contradiction.  By continuity of $f$, I see that $f(0)=\lim\limits_{k \to \infty}f(1/2k)=\lim\limits_{k \to \infty}(1/2k)=0.$  I also see that $f'(0)=\lim\limits_{h \to 0} \frac {f(h)} h=\lim\limits_{k \to \infty} \frac {f(1/2k)} {1/2k}=1$.  Since the zeroes of a non-identically-zero function are isolated, $\exists r>0[0<|z|<r \to f(z)\neq 0] $  Is there a way to derive a contradiction from the above statements?

I was working out some problems from a entrance test paper, and this problem looked a bit difficult.    Does there exist an analytic function on $\mathbb{C}$ such that $$f\biggl(\frac{1}{2n}\biggr)=f\biggl(\frac{1}{2n+1}\biggr)=\frac{1}{2n} \quad \ \text{for all} \ n\geq 1?$$   I did apply $f$ repeatedly to get some more insights about the problem, but couldn't get anything from it. So how do i solve this one?


I discovered this post   Does autotrash itself runs automatically?  If not, how to config it?

I want to schedule a task to run on a regular basis and have heard that Cron is the way to do this.  How do I add Cron jobs in Ubuntu?


inspired by  at first I thought 3 faces of a cube and half a sphere seem opposite extremes both with 50% surface area visible. then I considered a regular triangular pyramid which can be seen with 75% area.  Is this the maximal visible percentage for a regular platonic solid?  what about a regular polyhedron?

What is the highest percentage of surface area that can be seen at any given moment on a symmetrical object?  On a sphere its 50% right? (or close to it)  On a four-sided pyramid viewed from one of its points it would be 75%?  Can you get any higher?


I am trying to enumerate a range of integers using a variable but having some trouble.  When I type  echo {1..5}   I get  1 2 3 4 5   However, when I type a variable, I am unable to get the enumeration.  For example  $ num=5 $ echo {1..$num} {1..5}   I am stumped as to why the result is not the same.  I have tried using quotes and that has not helped either.  Can someone help or explain?

I want to use $var in a shell brace expansion with a range, in bash. Simply putting {$var1..$var2} doesn't work, so I went "lateral"...   The following works, but it's a bit kludgey.    # remove the split files echo rm foo.{$ext0..$extN} rm-segments > rm-segments source rm-segments   Is there a more "normal" way?


How can I see crash log on original iPad?

It's cumbersome to sync with iTunes to get a crash report. I'm looking for an app that can view and copy/paste or email crash reports from any other app on my iPhone. I want to see the full stack trace from the crash.  Is there an app for that?


I need to find the first empty line in the text file using the sed command regular expression.  below is the content that I have   this is defile to be cleaned skip rest consl   In the above content, I need to find only the first line that is an empty line and delete the first line.  I have used below regular expression, but it did not work for me, it is finding empty lines everywhere in the file.  ^\s*$

I would like to update a large number of C++ source files with an extra include directive before any existing #includes. For this sort of task, I normally use a small bash script with sed to re-write the file.   How do I get sed to replace just the first occurrence of a string in a file rather than replacing every occurrence?  If I use  sed s/#include/#include "newfile.h"\n#include/   it replaces all #includes.   Alternative suggestions to achieve the same thing are also welcome.


For example: if you are using a Maul, can you make an attack with it, sheath it, and then make an attack with a Greatsword, potentially doing this with four different weapons when unlocking the fighter's Extra Attack (4) feature?

When one uses the Extra Attack class feature, must it be done with only one weapon?  If I had, for example, one throwing axe and sword, couldn't I throw the axe and attack with the sword as part of the same "extra attack action"?


What is the intuition behind the fact that: $$ 0.9999999\ldots = 1 $$ My Teacher's Proof: We know that any number which belongs to the interval $[0,1)$ can be uniquely written as decimal expansion: $$ x=0.a_1a_2a_3 \ldots = a_1×10^-1+a_2×10^-2+a_3×10^-3 + \ldots $$ where the digits $a_1,a_2,a_3 \ldots$ satisfy the following: Each digit $a_i$ is an integer in the 10-element set ${0,1,2,....,9}$ So, $$ 0.9999999 \ldots = \frac{9}{10} + \frac{9}{100} + \frac{9}{1000} \ldots = 9 [$\frac{1}{10} + \frac{1}{100} + \frac{1}{1000} \ldots$)] = 9 × \frac{1}{9} = 1 $$ My doubt: Since $$ [\frac{1}{10} + \frac{1}{100} + \frac{1}{1000} \ldots)] ≈ \frac{1}{9} $$ So $0.9999999 \ldots ≈ 1$ not exactly equal to $1$. Am I correct? Suppose some people jump towards the right with velocity $u$ relative to a cart. Let the mass of each person be $m$ and that of cart be $M$. If there are $N$ people then, $Nm=M$ Case 2: All people jump simultaneously. $$ \Rightarrow Nm(u-v_B)=M(v_B) $$ Hence, $v_B=\frac{u}{2}$ Case 1: People jump one after other. After the first man jumps off the velocity $v_1$, acquired by the cart to the left, $$ m(u-v_1)=(M+Nm-m)v_1 $$ Hence, $v_1 = \frac{mu}{M+Nm}$ After the second person jumps off, the velocity $v_2$ acquired by cart to the left, $$ m(u-v_2)+(M+Nm-m)v_1=(M+Nm-2m)v_2 $$ Hence, $v_2=v_1+\frac{mu}{M+Nm-m}$ Similarly, after the $n^{th}$ person jumps off, the velocity $v_n$ acquired by the cart to the left $(2≤n≤N)$. So, $v_n=v_{n-1}+\frac{mu}{M+Nm-nm}$ Therefore the velocity $(v_A)$ after all people have jumped off, $$ v_A=\frac{mu}{M+Nm}+\frac{mu}{M+(N-1)m}+\cdots+\frac{mu}{M+m} $$ How do I proceed from here? Answer:  $$\frac{v_A}{v_B}=2ln2 $$

I'm told by smart people that $$0.999999999\ldots=1$$ and I believe them, but is there a proof that explains why this is?