I feel incredibly stupid and awful about this, but a while ago I jokingly referred to my daughters' poo (in her nappy, not in the toilet) as a monster (because it was so big).  I think I have now given her a fear of pooping and having her diaper changed. I need to start toilet training but think I have really set her back now.  She now only poos every 2-3 days and tries to avoid diaper changes. I am going to start talking about how nice her poos are and praise her but has anyone else found something useful in this situation?

My son is almost 3 (33 months) and for the past few months, he has been holding his poop in, to the point that he won't go for many days a time. When this started, the doctor advised us to give him Miralax to make his stool softer so it comes out more easily. Even with the Miralax, he still managed to hold it for two days at a time sometimes, but at least it was coming out at all, so we continued with it.  Anyway, we've been giving him the Miralax for months now, and now he's (supposed to be) going to preschool in September, which of course requires that he be potty trained. We don't want to hold him back since he's developmentally ready otherwise, so we started potty training a few weeks ago.  He picked up the potty training really quickly – for peeing – but he still holds his poop in no matter what. If he's sitting on the potty, as soon as he's about to do it, he stands up and just keeps holding it in (and once he starts to stand, if we even so much as ask him to sit back down, he screams and cries).  We have tried everything to convince him (or distract him enough) to sit and poop: reading books, singing songs, playing games, playing with toys, offering him snacks/treats (graham crackers), giving him stickers, etc. Nothing works.  As of today, it has been a week since the last time he pooped, with the exception of a little bit today and a little bit yesterday (both of which ended up all over the bathroom floor since he won't sit down). The doctor says now we should give him an enema to force it all to come out, but even so, that won't solve anything going forward since he still won't go in his diaper or on the potty in the first place (what are we going to do, give him an enema every week, indefinitely?).  The issue isn't that he's scared of the potty itself, since (a) he was holding it before we started potty training, and (b) he knows exactly what he's supposed to do, since he has no problem with peeing (he sits down himself, points it out afterward, knows that it gets emptied into the big potty, etc.).  It's that he just won't poop, ever – not in his diaper, not on the potty – and the only reason why anything comes out at all is because we've been giving him the Miralax every day (and even then, these aren't "full" poops, just whatever happens to come out because it's soft enough that he's unable to hold it all in).  I'm at a complete loss as to why this even started, and what if anything we can do that would actually help. Is it a behavioral problem? Medical? Both?? Help!    UPDATE: I just wanted to update this question since a lot has changed since I originally posted it. We discovered there was a specific situation where he would go in his diaper voluntarily: in our bedroom closet with the door closed. So we knew then that the withholding was intentional, since it was now established that he could go if he wanted to.  So we let him continue going in the closet and, over time, found that he usually went around the same time each day. Based on that, we then had him sit on the potty when we knew it was most likely he would need to go. We also managed to find two things that distracted him enough to sit (blowing bubbles and playing with his toy laptop).  By doing this, we were able to get him to go on the potty without really realizing it (so he didn't try to fight it), and then made a big deal out of it every time he did. Over time, that helped establish that that's what he was supposed to do, and now he does so voluntarily. He hasn't pooped in his diaper in probably 3 weeks by now.  I wouldn't say he's "fully" potty trained, in that an adult still needs to go with him and distract him (and occasionally remind him when he needs to go in general), but finally we made progress.


I have an ArrayList that I am accessing in a Thread inside onStart method in JavaFX. When I am trying to access the ArrayList from another Thread again in a method that is triggered by a MenuItem it's null and I can't understand why.  Sample program:  package sample;  import javafx.application.Application; import javafx.event.ActionEvent; import javafx.fxml.FXML; import javafx.fxml.FXMLLoader; import javafx.scene.Parent; import javafx.scene.Scene; import javafx.stage.Stage;  import java.util.ArrayList;  public class Main extends Application {      private ArrayList<Integer> testArray;     private Thread t;      @Override     public void start(Stage primaryStage) throws Exception{         FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("sample.fxml"));         fxmlLoader.setController(new Main());         Parent root = (Parent)fxmlLoader.load();         primaryStage.setTitle("Hello World");         primaryStage.setScene(new Scene(root, 300, 275));         primaryStage.show();          testArray = new ArrayList<>();         testArray.add(10);         t = new Thread(() -> {             System.out.println("Test number is "+testArray.get(0));         });          t.start();     }      @FXML     public void menuItemActionMethod(ActionEvent event) {         Thread t2t = new Thread(() -> {             System.out.println("Test number is "+testArray.get(0));         });          t2t.start();     }       public static void main(String[] args) {         launch(args);     } }   sample.fxml  <?xml version="1.0" encoding="UTF-8"?>  <?import javafx.scene.control.*?> <?import java.lang.*?> <?import javafx.scene.layout.*?> <?import javafx.geometry.Insets?> <?import javafx.scene.layout.GridPane?> <?import javafx.scene.control.Button?> <?import javafx.scene.control.Label?>   <GridPane alignment="center" hgap="10" vgap="10" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8">    <columnConstraints>       <ColumnConstraints />    </columnConstraints>    <rowConstraints>       <RowConstraints />    </rowConstraints>    <children>       <Pane prefHeight="200.0" prefWidth="200.0">          <children>             <MenuBar>               <menus>                 <Menu mnemonicParsing="false" text="File">                   <items>                     <MenuItem mnemonicParsing="false" text="Close" />                   </items>                 </Menu>                 <Menu mnemonicParsing="false" text="Edit">                   <items>                     <MenuItem mnemonicParsing="false" onAction="#menuItemActionMethod" text="Delete" />                   </items>                 </Menu>                 <Menu mnemonicParsing="false" text="Help">                   <items>                     <MenuItem mnemonicParsing="false" text="About" />                   </items>                 </Menu>               </menus>             </MenuBar>          </children>       </Pane>    </children> </GridPane>   The output is the following:  Test number is 10 Exception in thread "Thread-5" java.lang.NullPointerException     at sample.Main.lambda$menuItemActionMethod$1(Main.java:39)     at java.lang.Thread.run(Thread.java:745)   I have attached menuItemActionMethod in FXML in Delete MenuItem. Running the sample and accessing Delete in the application should run the Method.

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?


I read a  of the Canon EF 24-105mm f/4L IS USM lens. It said:   Focus shifts while zooming. Zoom before you focus.   Surprised by this (I don't recall ever seeing the focus scale shift while zooming), I took my 24-105mm lens, and manually focused so that the focus scale was at 3 meters distance at the 24mm end. I then zoomed in to 105mm end, and the focus scale was still at 3 meters. So, zooming doesn't affect the focus scale at all (it might affect how autofocus sees things, however).  So, is the lens parfocal or not? If Ken Rockwell is right, this means the focus scale is accurate only at a certain focal length.

In photo cameras, i.e. (D)SLRs, digital cameras, etc., when you focus on an object and then you zoom (in or out), the object gets out of focus. On the other hand, in movie or TV cameras, the focus is kept across the whole zoom range. It is even the best practice to focus while zoomed in the most so that the focus is the best possible, and then zoom out as needed.  What is the difference in construction of the lenses for photo cameras compared to the movie/TV cameras? Or is this effect achieved in some other way than lens construction?


The network-wide counter on the top displayed the correct +9 value, but the activity page showed 8:

A downvoted and subsequently removed post showed  as being -1, which is clearly wrong.  The  was the only post affecting my reputation since the last view (as can be seen by the yellow shade), so it should have been 0.


I refer to these formulas:  $\sin(x±y)$ and $\cos(x±y)$  Is there an obvious or intuitive proof to derive their simpler identities in terms of $\sin(x), \sin(y), \cos(x), \cos(y)$?  I am tagging this with complex analysis because I'm open to such an explanation if it's simple enough to understand.

The "" formulas often come in handy, but it's not immediately obvious that they would be true.  \begin{align} \sin(\alpha \pm \beta) &= \sin \alpha \cos \beta \pm \cos \alpha \sin \beta \\ \cos(\alpha \pm \beta) &= \cos \alpha \cos \beta \mp \sin \alpha \sin \beta \end{align}  So what I want to know is,    How can I prove that these formulas are correct? More importantly, how can I understand these formulas intuitively?   Ideally, I'm looking for answers that make no reference to Calculus, or to , although such answers are still encouraged, for completeness.


I have a piece of code I am trying to understand , this is an Java-Android Based .       volumeControl.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {          @Override         public void onStartTrackingTouch(SeekBar seekBar) {         }          @Override         public void onStopTrackingTouch(SeekBar seekBar) {         }          @Override         public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {             audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0);         }      });   In this code there an @Override method done inside the parentheses is this the best way to do this code and how this is done .    How the java compiler understand this constructor call. There is a int variable called progress from where it gets it's value , how the function call is done.

What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?


I'm legally banned from the US and I need to get to Cost Rica or at least close to it. I can't find any direct flights from Ottawa or Montreal.   Will they arrest me if I land in the US for a flight transfer? Will they see that I am banned? Do they scan the passports?

I am a Canadian citizen and I have been denied from the USA in the past 2 years and last year I entered illegally and was caught and given voluntary departure, but I do not have a criminal record in the USA or Canada.   NOW - I am currently in Costa Rica and looking to fly back to Canada, and it would be ideally priced with a stop in the USA. I am not banned from entering the USA for any amount of time but CBP has said I need to present 12 consecutive months worth of pay stubs and rent receipts proving my ties to Canada. Is there any way I can take a flight from Costa Rica with a stop in the USA? Is my onward flight ticket proof enough? Or will I be turned back before boarding in the airport in Costa Rica? Is there a number I can call to ask US customs about my legal situation?


how do I install ubuntu.iso (downloaded from ubuntu.com[more than 700mb]) in my windows 7 ultimate 32bit. please explain step by step.. thanks

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


I am seeking for an intuitive and logic explanation for the degree of freedom of Linear Regression. Why the degree of freedom for Linear Regression is N-k with N is the number of observations and k is the number of features. Could you help to demonstrate this N-k result?

From , there are three interpretations of the degrees of freedom of a statistic:     In statistics, the number of degrees of freedom is the number of   values in the final calculation of a statistic that are free to vary.      Estimates of statistical parameters can be based upon different   amounts of information or data. The number of independent pieces of   information that go into the estimate of a parameter is called the   degrees of freedom (df). In general, the degrees of freedom of an   estimate of a parameter is equal to the number of independent scores   that go into the estimate minus the number of parameters used as   intermediate steps in the estimation of the parameter itself (which,   in sample variance, is one, since the sample mean is the only   intermediate step).      Mathematically, degrees of freedom is the dimension of the domain of a   random vector, or essentially the number of 'free' components: how   many components need to be known before the vector is fully   determined.   The bold words are what I don't quite understand. If possible, some mathematical formulations will help clarify the concept.  Also do the three interpretations agree with each other?


How do I show that for $n \geq 0$,  $$\sum_{k=0}^n \binom{n}{k}^2 = \binom{2n}{n}?$$  I know that $\sum_{k=0}^n \binom{n}{k} = 2^n$, but does this really tell me anything? Thanks.

I was hoping to find a more "mathematical" proof, instead of proving logically $\displaystyle \sum_{k = 0}^n {n \choose k}^2= {2n \choose n}$.  I already know the logical Proof:  $${n \choose k}^2 = {n \choose k}{ n \choose n-k}$$  Hence summation can be expressed as:  $$\binom{n}{0}\binom{n}{n} + \binom{n}{1}\binom{n}{n-1} + \cdots + \binom{n}{n}\binom{n}{0}$$  One can think of it as choosing $n$ people from a group of $2n$  (imagine dividing a group of $2n$ into $2$ groups of $n$ people each. I can get $k$ people from group $1$ and another $n-k$ people from group $2$. We do this from $k = 0$ to $n$.


I don't have much to go by here... but I'll give it a shot. I would have to say this movie was set in the late 80's early 90's. (May possibly be an episode of a TV show)  I remember one of the characters was an Asian guy who at one point jumps through a spinning fan/vent. The jump is in slow motion, and he lands on the other side of the spinning fan blades and kicks the fan from the other side to stop the blades from spinning, allowing the other people with him to get through.   I wanna say that the main character/hero is sort of a Robocop-type character. I even thought at one point that it WAS Robocop.. but I skimmed through the Robocop movies and couldn't find any familiar scenes. I remember that the three heroes of the movie were this potential "Robocop-like dude", the Asian dude, and a kid. There may have been a forth but I can't remember. At the very end of the movie, the "bad guy" was in some sort of air craft or space ship or laboratory or something, and he laughs just before the whole place explodes. I'm pretty sure the bad guy had a beard and mustache.

This is an incredibly vague scene depiction, but I'm trying to recall a sci-fi movie I watched as a very young kid. It would have been out perhaps early 80s.  I don't recall any of the story but the image has stuck in my head and for years I always wanted to know what the movie was about. I recall a man (possibly a cyborg) who carried a shield, and for the scene I recalled drove/hovered around on something that resembled a segway or a one person standing hover craft. There was a lot of shooting going on. He may (may!) have had red infared vision like terminator (although I may just be getting that part mixed up with terminator :) I know if I saw the scene again, I'd sure to recognize it.   Anyway if anyone has the slightest inclination to what film this may be, I'd love to hear. Sorry there isn't much more I recall, I guess this is the last chance for me to put this to bed :)


If $A=B+C$, where $B=\begin{bmatrix}a &b &c\\   d& e& f\\ g &h& i\end{bmatrix}$ and $C=\begin{bmatrix}k &k &k\\   0& 0& 0\\ 0 &0& 0\end{bmatrix}$, then $|A|=|B|+|C|$. Since $|C|=0$, so, $|A|=|B|$. But, if we consider the properties of determinants, then $\left| \begin{array}{c c c} a+k & b+k & c+k \\ d & e & f \\ g & h & i \end{array}\right|=\left| \begin{array}{c c c} a & b & c \\ d & e & f \\ g & h & i \end{array}\right|+\left| \begin{array}{c c c} k & k & k \\ d & e & f \\ g & h & i \end{array}\right|$. Thus, $|A|\ne|B|$. What is wrong in the first method?

I'm trying to calculate the following determinant: $$\begin{vmatrix} a_0 & a_1 & a_2 & \dots & a_n \\ a_0 & x & a_2 & \dots & a_n \\ a_0 & a_1 & x & \dots & a_n \\ \dots & \dots & \dots & \dots & \dots \\ a_0 & a_1 & a_2 & \dots & x \end{vmatrix} = $$ $$ = \begin{vmatrix} a_0 & a_1 & a_2 & \dots & a_n \\ a_0 & a_1 & a_2 & \dots & a_n \\ a_0 & a_1 & a_2 & \dots & a_n \\ \dots & \dots & \dots & \dots & \dots \\ a_0 & a_1 & a_2 & \dots & a_n \end{vmatrix} + \begin{vmatrix} 0 & 0 & 0 & \dots & 0 \\ 0 & x - a_1 & 0 & \dots & 0 \\ 0 & 0 & x - a_2 & \dots & 0 \\ \dots & \dots & \dots & \dots & \dots \\ 0 & 0 & 0 & \dots & x-a_n \end{vmatrix} = 0 + 0 = 0 $$  Still, experimental results contradict, since for one example I get a non-zero determinant.  What am I doing wrong?


I have SharePoint list. I have added Event receivers on SharePoint list for ItemAdded event.  Also I have SharePoint designer workflow on same list which triggers on Item created and Item Updated.  I would like to know which actually gets trigger first. Event Receiver or Workflow?  Please explain reason. also I would like to know if I have ItemUpdated event receiver and Designer workflow for trigger when item get updated.

Is it possible to know beforehand whether event receivers on a list will always execute before any workflows associated with that list?


I'm trying to write a loop that uses scanner to add integers to an established integer array list. It has to to be able to terminate the integer entries and proceed once "x" is entered, and prompt the user to re-enter an integer if any other letter is entered. My problem is that using .nextInt() I get run-time errors when entering a String. Am I simply using the wrong scanner method? This is what I have so far. I imported java.util.*  public static void main (String [] args)    {       Square square = new Square(); //constrcutor that establishes array list "square"       Scanner in = new Scanner(System.in);       int value = 0;        while (value != "x")       {          System.out.print("Enter an integer(x to exit): ");          value = in.nextInt();           if (in.nextInt() != "x" || value !> Integer.MIN_VALUE && value !< Integer.MAX_VALUE)          {             System.out.println("end");             System.exit(0);          }       square.add(value);          }    }

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


If I sell a car or boat at a profit, I assume I have to pay a capital gains tax.  Does it work in reverse as well? Can I declare a capital loss if lose money on the sale of a car or boat?

If I sell my car off at a loss, can I write that loss off against my income to save on tax? Does it matter if the car was used just for personal leisure use, or if I used the car to generate business income? (e.g. travel to work, to attend education seminars, etc.)


The rectangular equation is $$x^2+y^2-8z^2=0$$ $$x^2+y^2=8z^2$$ Know in the relationship between rectangular and spherical coords. we can manipulate our given to fit the form: $$x^2+y^2+z^2=9z^2$$ $$\rho^2=x^2+y^2+z^2, \space z=\rho\cos(\phi)$$ $$\rho^2=9\rho^2\cos^2(\phi)$$ $$1=9\cos^2(\phi)$$ $$\frac{1}{3}=\cos(\phi)$$ $$\arccos\left(\frac{1}{3}\right)=1.23 \space rads$$ And so the equation in spherical coords. is $\phi=1.23$ I know my math is correct but I have the wrong answer so ilm not sure where I went wrong.

The rectangular equation is $$x^2+y^2-8z^2=0$$ $$x^2+y^2=8z^2$$ Know in the relationship between rectangular and spherical coords. we can manipulate our given to fit the form: $$x^2+y^2+z^2=9z^2$$ $$\rho=x^2+y^2+z^2, \space z=\rho\cos(\phi)$$ $$\rho^2=9\rho^2\cos^2(\phi)$$ $$1=9\cos(\phi)$$ $$\frac{1}{3}=\cos(\phi)$$ $$\arccos(\frac{1}{3})=1.23 \space rads$$ And so the equation in spherical coords. is $\phi=1.23$ I know my math is correct but I have the wrong answer so I'm not sure where I went wrong.


I was wondering if someone could answer a question about the internals of bibtex.  I have a bibtex file that works well when the files are neat. For example  @article{HochwaldTC03, author = "{B.M. Hochwald} and ten Brink, S.", title = "{Achieving near-capacity on a multiple-antenna channel}", journal = "IEEE Transactions on Communications", ... }   works just fine. However, when I pull a bibtex citation from google scholar, it comes out like   @article{kenward2007multiple,   title={Multiple imputation: current perspectives},   author={Kenward, Michael G and Carpenter, James},   journal={Statistical Methods in Medical Research},   ...       }   There are brackets alone (instead of brackets and quotes). When I add this to my bib file, bibtex (or latex, I'm not sure) freaks out and cannot read it. I was wondering why this is.  I feel that if google scholar is putting it out with just braces, it's probably correct. Can anyone tell me how to make bibtex work when it only has braces?  Edit: I think it might be a bibtex compilation thing. I'll update soon.  It is in fact a bibtex thing. What I do is copy and paste the google scholar bibtex citations, and then compile bibtex twice, and then pdflatex 2 or 3 times and it works. But why is it like this?  It isn't an issue, the braces just make the word a unit that cannot be broken. My issue was with it not updating (which I attributed to braces), but the real problem was just with the order in which I ran bibtex and pdflatex.

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


Passport : Sri Lankan Holding a valid US Visa (F1). Spending only 3.15 hours at Toronto Airport. Flying in through United and leaving to my next layover (London) in Air Canada.

I'm passing through Canada, on my way to somewhere else. I'm staying only a short time.   Is there a website, or some other way of find out out if I need a visa?


For example  struct Option_1 {     template<class T> using Vector = std::vector<T>; };   I can do  typename Option_1::Vector<int> v;   But I prefer the following  Vector<Option_1, int> v;   or similars without the word "typename". I define an alias  template<class Option, class T> using Vector= typename Option::Vector<T>;   but failed with unrecognizable template declaration/definition. How to fix it?

In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway?    I have the following code:  template <typename T, typename Tail> // Tail will be a UnionNode too. struct UnionNode : public Tail {     // ...     template<typename U> struct inUnion {         // Q: where to add typename/template here?         typedef Tail::inUnion<U> dummy;      };     template< > struct inUnion<T> {     }; }; template <typename T> // For the last node Tn. struct UnionNode<T, void> {     // ...     template<typename U> struct inUnion {         char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U     };     template< > struct inUnion<T> {     }; };   The problem I have is in the typedef Tail::inUnion<U> dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion<U> names a type and not a function?


I've noticed that a lot of (especially older) content on Meta (and other places) which links directly to other content on the same site, following the link results in a 404 error.  Especially since the link target and destination are both on the same site, it seems like it would be especially possible for a script to run periodically and add strikethrough formatting to dead links.    Notice that I am not proposing either of the following:   A system for notifying AUTHORS of broken links in their posts to try to get them to fix something, as is proposed .   A moderation queue where people who come  can report them for MANUAL moderation, as suggested by Shadow Wizard.   I am instead proposing an AUTOMATIC way to format text to visually help READERS not waste their time clicking on dead links.

It would be really nice if SO scanned posted content and checked detected links, and then notified the user of bad or redirected links so they could verify links are still valid and/or fix them.


Have this situation where Windows Explorer hangs indefinitely every time I open it (Windows 10). But when you open Explorer for a specific folder (for instance by entering C:\ in the start menu search box) it opens and runs just fine. And without any delay. Everything is alright until you accidentally click on "Quick Access", then it also freezes. So it appears that it wants to show the "Quick Access" items by default. Quick Access appears to be the modern variant of the recently opened files list. Workaround: Elsewhere on the web I learned that if you have a chance to run explorer normally, you can temporarily fix the situation. If you have it running normally:  right click on the top left "Quick Access" tree node in the navigation pane choose "Options" from the popup menu find the "Privacy" group box in the dialog press the "Clear" button.  This makes the quick access screen forget about all the files - which possibly includes missing, broken or just very large files. So the bottom line is that there is a problem with this "Quick Access" frame, but how to debug something like this? Tried debugging with Visual Studio but then it only shows that the project is blocking on one of the win32 wait functions.

Does anybody know how to get rid of the annoying "Working on it ..." Message in the Windows 10 File Explorer.  It stays there (on the right side) for a few seconds to many seconds when opening the file explorer.  OS Window 10 System Partition SSD All other files which are used often are also on a SSD (only one HDD for bigger files which are also not used often, exists)  So showing recent files should really be fast. Also I do not mind if there is an option to deactivate this feature.


I spent this whole weekend trying to come up with a solution on my MSI GT70. Right now, I can boot using a Live USB under legacy mode with nomodeset.  However, I have trouble with booting it under UEFI. I tried following steps;   I disabled fastboot Disabled quick boot in win8.1 (I upgraded the pre-install system),  Ininstalled Intel rst  My SATA is under ACHI, so I disabled secure boot (though I'm sure that's not the case) Enabled CSM, I tried acip=off   none of these worked for me under UEFI. I even tried to install 12.04 LTS and 13.10 by changing the USB several times.  I'm frustrated and have no idea what to do now. There must be something that I'm missing. Because, when I used nomodeset, it runs into bunch of lines, and after that is a black screen. I never get to see the X desktop, It's always a black screen.  Can someone advise me what to do?  I tried everything on that post, nothing works, I can't boot my live USB, please do not just mark it as duplicate

I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS.  Should I do it with Wubi, or through the Live USB/DVD?  What steps do I need to take to correctly install Ubuntu?


Why is the electric field due to a charge enclosed by a Gaussian surface inside an uniformly charged thin spherical shell, zero?

It is quite easy to derive the gravitational field intensity at a point within a hollow sphere. However, the result is quite surprising. The field intensity at any point within a hollow sphere is zero.   What exactly is the reason behind this? Except for, of course, the mathematics behind it. Is there any logic why the field intensity should be zero within a sphere? For example, it is logical to say that the field intensity would be zero at the center, as all the intensities cancel out. However, this cannot be the case for any point within the sphere.


(Sorry if this question was asked here before, but I searched for it for hours now, and couldn't find anything. Someone said that what I want is possible, and he told me how, I did as he said yet it is total failure.)  First of all, here is a class diagram for the easier presenting of the question.     Then the code which doesn't do what I want:  int main() {     Employee jack("Jack", 100);     People guys(jack);             // using push_back  ... }   So when this happens, as the debug mode shows, guys[0] will only have a name, no salary. Is it even possible, to an object in the vector to have other members than name? Or my only choice is to make an Employee vector?  Edit: Person is virtual by the way.

Someone mentioned it in the IRC as the slicing problem.


I was trying to link part of an article on wikipedia - specifically  to refer to a specific section of the wikipedia entry. It quotes start of the article, as opposed to the part of the article I was trying to link to - it was a little confusing.    The onebox for     The section that the link actually points to.  Note that the link still works - it takes you to the correct section. But, the onebox implies it will go to the top-level article instead, which is confusing.   So... could we get oneboxes to be aware of sections in pages - they do seem to use a standard notation.

Not sure if this is a bug or a feature, but I noticed today that if I , it annoyingly one-boxes a link to the room, which is not a link to the info page! That's it. I'm gonna pack up and leave! Such annoyance! But for the time being,  Is this behavior expected? If so, what is the reason for changing the links? If this is really a bug since the responsible bot is not seeing parts of the URLs and ends up one-boxing, and hence linking to the wrong message, could this be fixed please? Worth pointing out that too much exposure to annoying things results in a higher blood pressure.


Can somebody explain why the numbers don't match up? Why is the reported size of the selected items less than subtracting the volume's free space from its total size?

How can I visualize which folders and files are taking up all of the space on my hard drive?  I'm getting some conflicting reports on the size of hard drive contents. Namely what is and isn't there and what folders are actually using the space.   I need to know which of the files or folders the culprits behind all this hidden bloat. Also there should be a print option to get it on paper.


Latex fails building the following code with error "Emergency stop."  \documentclass{article} \usepackage{tikz-qtree} \begin{document}     \begin{tikzpicture}     \Tree       [.a         [.b              [.c                 [.d                     [.e                         [.f]                     ]                 ]             ]         ]     ]     \end{tikzpicture} \end{document}   After removing the ".f" child, it compiles fine. Is there some limitation to qtree I have reached?

I've scoured this forum and it looks to me like I'm setting up the tree correctly, but I'm still getting this error, I have   \usepackage{tikz} \usepackage{tikz-qtree}   in the header.  Here is the code that is causing the problem:  \begin{tikzpicture}  \Tree  [.{Boolean Groups}     [.{Abelian Groups}         [.Groups]     ]     [.{Class 3}          [.{Class 5}]         [.{Class 1}]         [.{Class 2}]         [.{Class 4}]     ] ]  \end{tikzpicture}


UNEXPECTED INCONSISTENCY : RUN fsck MANUALLY  The root filesystem on /dev/sdb9 requires a manual fsck  BusyBox v1.21.1(Ubuntu 1:1.21.0-1ubuntu1) built in  shell(ash)  (initramfs)_

I dual boot Ubuntu and Windows 7. I was browsing on FireFox in Ubuntu and all of a sudden I get some error message, so I rebooted.  Now when I try to boot into Ubuntu I get this message:  fsck from util-linux 2.26.2 /dev/sda6 contains a file system with errors, check forced. /dev/sda6: Inodes that were part of a corrupted orphan linked list found.  /dev/sda6: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.         (i.e., without -a or -p options) fsck exited with status code 4 The root filesystem on /dev/sda6 requires a manual fsck  Busybox v1.22.1 (Ubuntu 1:1.22.0-15ubuntu1) built in shell (ash) Enter 'help' for a list of built-in commands.  (initramfs) _   How can I fix this?


Which statement is correct?  Alcohol, drug abuse and work equipment is a lethal mix.  or  Alcohol, drug abuse and work equipment are a lethal mix.

Possible Duplicate:          Would I use is or are in the following sentence?      The Pohutakawa Coast, Hauraki Gulf, and Waiheke Island is/are the backdrop for our day.   If I rewrote it so the subject (backdrop) starts the sentence, then it seems to me that as it is singular, the verb should be the singular is. But as it is written above, are seems less clumsy.


I read that the norm of a linear functional $f:V\to K$, with $K=\mathbb{R}\lor K=\mathbb{C}$, associated to the $p$-norm $\|x\|=(\sum_{i=1}^n|x_i|^p)^{\frac{1}{p}}$, for $p>1$, is $$\|f\|=\Big(\sum_{i=1}^n|f(e_i)|^q\Big)^{\frac{1}{q}}$$  where $\frac{1}{p}+\frac{1}{q}=1$ and $e_i,i=1,...,n$ are the elements of the basis of $V$.  Does anybody know a link to a proof or a proof of the fact that $\|f\|:=\sup_{\|x\|=1}|f(x)|=\sup_{\|x\|\leq 1}|f(x)|=\sup_{x\ne 0}\frac{|f(x)|}{\|x\|}$ is equal to $(\sum_{i=1}^n|f(e_i)|^q)^{\frac{1}{q}}$?  I know that for any $x=a_1 e_1+...+a_n e_n$ we have $f(x)=\sum_{i=1}^n a_if(e_i)$, but I cannot go further...  EDIT: I thank all the users that have linked the other question bearing a strong similarity with mine. I'm not deleting it, though, because I suppose the slight difference can make it useful for future readers of this site.

Let $\| \cdot \|$ be a norm on $\mathbb{R}^n$. The associated dual norm, denoted $\| \cdot \|_*$ is defined as $\| z \|_* = \sup\{ z^{t} x : \| x \| < 1 \}$.   Does someone know how to prove that the dual norm of the $\mathcal l_{p}$ norm is the $\mathcal l_{q}$ norm? I read about norms and it was stated without proof in a book.


Which of the following two sentences is correct:  Jon (and Michael) is smart. Jon (and Michael) are smart.   This example is clearly contrived but my question is whether the sentence should be grammatically correct when you erase the text in parentheses (Jon is smart) or should it be grammatically correct when read with the text in parentheses (Jon and Michael are smart).

If a set of parentheses lies between a subject and its verb, and the parentheses contain an substitutive subject whose singularity/plurality disagrees with the original subject, whose singularity/plurality should be chosen for the verb?  In other words, in the following example, should "questions" (and its verb "are") be singular, or should they remain plural as shown?     Many (if not every) questions on this StackExchange are answered.   My intuition tells me that the two words in question should remain in plural forms, since the text in parentheses only interrupts the sentence (and the sentence would be grammatically incorrect if everything in parentheses were removed and the words were in singular form).  On the other hand, when read aloud (assuming one reads the text in parentheses), this has an uncomfortable sound to it, and I've seen others write in what would be the above example's singular-form case, so I'm curious to find out which is correct.  And, thinking about it, I suppose the same question would apply when commas are used in place of parentheses.


I want to show that solution of this Cauchy problem \begin{cases} u'(t)=u(t)^2 + t \\ u(0)=0 \end{cases} is defined for $t \in [0,\alpha]$, with $\alpha <3 $  I tried to integrate, but it's not possible because of the $t$. I can see that $u'>0$ for all $t \geq 0$ , and that's all. I don't know how to argue honestly

Let $f:[0,\alpha]\to\mathbb{R}$ be a solution of the Cauchy problem:  $\begin{cases} f'(t)=(f(t))^2+t \\ f(0)=0 \end{cases} $  The question is: prove that $\alpha<3$.  It is clear that the problem admits a unique solution locally on some $[-\epsilon,\epsilon]$, since $(f)^2+t$ is $C^1$ in $(f,t)$, and we have $f(t)>0$ for all $t>0$, looking at the sign of $f'$. But now I don't know how to proceed. Thank you all!


Is the  of two parallel resistors the resistance of the individual resistors or the sum of their resistances?   Is the $R_e$ of two series resistors their sum?

Which type of circuit would have the greater resistance?  Which type would have the greater current? and Why?  My book says that parallel has the greater resistance than current as parallel wiring if thought as water pump tubes has greater resistance during water flow.  Contrary to my book, if I make up numbers to solve for which has the greater resistance, i find that  series has greater resistance.  Equivalent resistance of 2 Ohm resistor in series is greater than that of 2 resistors with 2 ohms in parallel. I


I am running into a bit of an issue / quirk here:  [root@s06p5bcsmta001 elves]# TEST=$(cat -e sendlog) [root@s06p5bcsmta001 elves]# echo $TEST | wc -l 1 [root@s06p5bcsmta001 elves]# cat sendlog | wc -l 1050 [root@s06p5bcsmta001 elves]# TEST=$(cat sendlog) [root@s06p5bcsmta001 elves]# echo $TEST | wc -l 1 [root@s06p5bcsmta001 elves]# echo -e $TEST | wc -l 1   How do I get the contents of the text file (with \n) into the variable?

Or, an introductory guide to robust filename handling and other string passing in shell scripts.  I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some file names).  I encountered a problem such as the following:   I have a file name containing a space hello world, and it was treated as two separate files hello and world. I have an input line with two consecutive spaces and they shrank to one in the input. Leading and trailing whitespace disappears from input lines. Sometimes, when the input contains one of the characters \[*?, they are replaced by some text which is is actually the name of files. There is an apostrophe ' (or a double quote ") in the input and things got weird after that point. There is a backslash in the input (or: I am using Cygwin and some of my file names have Windows-style \ separators).   What is going on and how do I fix it?


At the end of the second season of Sherlock (from BBC 1), we see that sherlock tries to fake his death. The next session begins with an explanation of his method (using a rope and Moriarty's corpse). But there is another explanation which Sherlock reveals himself: he jumped on a crash mat, a similar-looking, dead person is brought to the pavement, and Sherlock replaces him. I'm just confused!   Which one was the real explanation? Why did he have to fake his death? Moriarty was already dead, and Mycroft had convinced the snipers to cancel their plan by phone calls. Who was Sherlock trying to fool? Why did they use the similar-looking corpse (according to Sherlock's own explanation)? When Watson got to the corpse, it had been replaced by Sherlock! There was no need to this part of the plan.

In Sherlock, BBC Series, Season 2 Episode 3 - The Reichenbach Fall, how did Sherlock survive the fall? I've read some theories online regarding this, but in this , Steven Moffat says "There is a clue everybody's missed". He also says "Yes. We had to have Holmes dying in Watson's arms – and get away with that, which we have."  So how? Does anybody know yet?


Hey I'm trying to test my selection sort algorithm but all the output I get in the console is just "[I@15db9742" Could someone please explain to me why I'm getting junk output? It is really baffling me, could it possible be a problem with the IDE or is it something in the code?   Thanks  import java.util.Arrays;   public class SelectionSorterTest {      // Factories      // Queries      /**      * Sorts a copy of the input array.      * @param input an array.      * @return a sorted copy of input.      */     public static int[] sort (int[] input) {         int[] sorted = Arrays.copyOf(input, input.length);         for(int i = 0; i < sorted.length - 1; i++)         {             int minIndex = i;             for(int j = i + 1; j < sorted.length - 1; j++)             {                 if(sorted[j] < sorted[minIndex])                 {                     minIndex = j;                 }             }             if(i != minIndex)             {                 swap(sorted, minIndex, i);             }         }         return sorted;     }       // Commands      // Private      // disabled constructor     private SelectionSorterTest () { }      private static void swap (int[] arr, int x, int y) {         int temp = arr[x];         arr[x] = arr[y];         arr[y] = temp;     }      public static void main(String[] args)     {         int[] Array = {9,7,6,4,3,2,21,1};         System.out.println(sort(Array));      }  }

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


I make a simple Intel assembly code to print a literal string containing a special character (ñ) in standard output that doesn´t print it in the correct way.  I'm using NASM to assemble, GCC to link, _printf function to print. Windows 10 is my OS.  global  _main extern  _printf section  .data msg     db  'The letter ñ is used in spanish language',0 section  .bss section .text _main: push    msg call    _printf          add     esp,4        ret   Below the details of commands to assemble, linker and the result of program execution:  C:\nasm-2.14.02\MisProg>nasm utftest.asm -f win32  C:\nasm-2.14.02\MisProg>gcc utftest.obj -m32 -o utftest  C:\nasm-2.14.02\MisProg>utftest The letter ├▒ is used in spanish language C:\nasm-2.14.02\MisProg>   I couldn't find out what is needed to do to print the letter ñ in the correct way.

We have a project in Team Foundation Server (TFS) that has a non-English character (š) in it. When trying to script a few build-related things we've stumbled upon a problem - we can't pass the š letter to the command-line tools. The command prompt or what not else messes it up, and the tf.exe utility can't find the specified project.  I've tried different formats for the .bat file (ANSI, UTF-8 with and without ) as well as scripting it in JavaScript (which is Unicode inherently) - but no luck. How do I execute a program and pass it a Unicode command line?


So, here's the full question: Let $\{a_n\}_{n=1}^{\infty}$ be a sequence of real numbers. Suppose that every subsequence of $\{a_n\}_{n=1}^{\infty}$ has a subsequence that converges to a real number $L$. Prove that $\lim_{n \to \infty} a_n = L$.  Proof Attempt: To prove this, let us define our terms very carefully. Let $\{a_n\}_{n=1}^{\infty}$ be the main sequence we are considering. Let $\{n_k\}_{k=1}^{\infty}$ be a strictly increasing sequence of natural numbers and let $\{k_m\}_{m=1}^{\infty}$ be a strictly increasing sequence of natural numbers as well. Now, let $\{a_{n_k}\}_{k=1}^{\infty}$ be a subsequence of the main sequence. By hypothesis, this subsequence has a subsequence that converges to $L$. Let's denote this particular subsequence by $\{a_{n_{k_m}}\}_{m=1}^{\infty}$. By the definition of convergence, for any $\epsilon > 0$: $$\exists M \in \mathbb{N}: \forall m \geq M: |a_{n_{k_m}}-L| < \epsilon$$ Since $\{k_m\}_{m=1}^{\infty}$ is a strictly increasing sequence of natural numbers, we note that: $$\forall m > M: k_m > k_M$$ Let $K := k_M$. Then: $$\exists K \in \mathbb{N}: \forall k \geq K: |a_{n_k}-L| < \epsilon$$ This follows directly from the previous statement we made. If $m \geq M$, then $k_m \geq k_M = K$. Then, since $\{n_k\}_{k=1}^{\infty}$ is also a strictly increasing sequence of natural numbers, for all $k \geq K$, $n_k \geq n_K$. Define $N = n_K$. Then, we can finally see that: $$\exists N \in \mathbb{N}: \forall n \geq N: |a_n-L| < \epsilon$$ That is precisely the assertion that $\lim(a_n) = L$. That proves the desired result. Is the proof above correct? If it isn't, why? How can I fix it? Edit 1: Suppose that $\{a_n\}_{n=1}^{\infty}$ does not converge to $L$. It either converges or it diverges. If it converges, then it converges to some real number $M \neq L$. So, every subsequence of this sequence converges to that same real number. So, every subsequence of each subsequence must also converge to $M$. That's a contradiction. If it diverges, then: $$\exists \epsilon > 0: \forall N \in \mathbb{N}: \exists n \geq N: |a_n-L| \geq \epsilon$$ Define the set $S = \{n \in \mathbb{N}: |a_n-L| \geq \epsilon\}$. I claim that this set is infinite. If it were finite, then we would just define $N = \max(S) + 1$. So, for any $n \geq N$, $|a_n-L| < \epsilon$ and the sequence converges. That would contradict our assumption. So, $S$ has to be infinite. (Uhhh not really sure where to go from here?) Edit 2: I'm not quite sure why this question was closed. Even though the statement I'm proving has been posted by others, this is my version of the argument and a whole separate discussion on the specific thought process that I used. Surely it might have some value for the individual stumbling on this site. Besides, the question I asked was specifically a solution verification. All my questions have been of that nature and I don't really understand why that's an issue.

Suppose that $(u_n)$ is unbounded above. Then, we pick any arbitrary monotone increasing subsequence $(v_n)$ of $(u_n)$. But by hypothesis, we can find a subsequence of $(v_n)$ that converges to $0$. Hence, $\lim v_n =0$. Therefore, $(u_n)$ must be bounded above.  Again, let $(u_n)$ be unbounded below. Then we pick any monotone decreasing subsequence $(w_n)$. By similar arguments, $(u_n)$ must be bounded below.   Being bounded, it has a finite $\limsup =l$ and $\liminf =m$.  Hence, there must be convergent subsequences $(a_n)$ and $(b_n)$ that converge to $l$ and $m$ respectively. But every subsequences of the above two must converge to $l$ and $m$ respectively (treating the two as convergent sequences). Again, by hypothesis, they both have subsequences that converge to $0$. Therefore, both $(a_n)$ and $(b_n)$ converge to $0$.   In conclusion, $\limsup u_n = \liminf u_n = 0 =\lim u_n$  Is this alright?


How to write a matrix like this    I tryed this   $$ \begin{pmatrix} J_0 & O &\cdots\\ 0& J_{n+1} & 0\cdots \end{pmatrix} $$   I don't know how to do

I am struggling to create the matrix in the picture attached using Latex. I have tried using commands like \hline but the matrix ends up looking messy as the line goes all the way across.    Edit: To clarify, I am looking for each block to have a square outline.


Let $f\colon \mathbb{R}\to\mathbb{R}$ be continuous, bounded function such that the space $\operatorname{lin}(\{f_k\mid k \in \mathbb{N}\})$ is finite-dimensional, where $f_k(x)=f(x+k)$.   What can we say about $f$?    Thank you in advance.

Let $f:ℝ→ℝ$ be continuous, bounded function such that the space $\mathrm{lin}\{f_k(x)=f(x+k)∣k ∈\mathbb{N}\}$ is finite-dimensional.  Determine an expression of f.  I started with:  Let $P_f(X) = \sum_{k=0}^n p_k X^k$,  the degree is n,and we define f on [0,n] but after I do not know how to continue.   Thank you in advance.


Here is my rather simple idea. I will treat the set of real numbers as a set of discrete continuities, each separated by an Epsilon ball that tends to 0.  So, let's say P(b) is true. We then assume P(k) is true, and prove that P(k+e) is true, where e goes to zero.  I just want to know if this is a valid technique or not because our teacher said that mathematical induction can only be applied to discrete structures, but I see no difficulty in treating a continuous system as a set of infinitesimal discrete quantities. Mak

One of my Fellows asked me whether total induction is applicable to real numbers, too ( or at least all real numbers ≥ 0) . We only used that for natural numbers so far.  Of course you have to change some things in the inductive step, when you want to use it on real numbers.  I guess that using induction on real numbers isn't really possible, since $[r,r+\epsilon]$ with $\epsilon > 0$, $r \in \mathbb R$ is never empty.  Can you either give a good reason, why it isn't possible or provide an example where it is used?


I've been compiling some codes and found that the -llibrary flag has no effect in linking. Haven't really dealt with C++ before, so may be a simple mistake...  Here is the command I am using:  compiling:  g++ -c -Wall -std=c++11 -I/usr/include/flycapture -I/usr/include/ -I/usr/local/include/opencv2 -I/usr/include/glibmm-2.4 -I/usr/lib64/glibmm-2.4/include -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include/ -I/usr/include/sigc++-2.0 -I/usr/lib64/sigc++-2.0/include/  -I/usr/include/boost   FrameRateCounter.cpp -o FrameRateCounter.o g++ -c -Wall -std=c++11 -I/usr/include/flycapture -I/usr/include/ -I/usr/local/include/opencv2 -I/usr/include/glibmm-2.4 -I/usr/lib64/glibmm-2.4/include -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include/ -I/usr/include/sigc++-2.0 -I/usr/lib64/sigc++-2.0/include/  -I/usr/include/boost   SaveVideoClass.cpp -o SaveVideoClass.o g++ -c -Wall -std=c++11 -I/usr/include/flycapture -I/usr/include/ -I/usr/local/include/opencv2 -I/usr/include/glibmm-2.4 -I/usr/lib64/glibmm-2.4/include -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include/ -I/usr/include/sigc++-2.0 -I/usr/lib64/sigc++-2.0/include/  -I/usr/include/boost   SaveVideo.cpp -o SaveVideo.o   linking:  g++ -L/usr/local/lib -L/usr/lib/x86_64-linux-gnu/ -lopencv_core -lopencv_highgui -lopencv_imgproc -lopencv_videoio -lsigc-2.0 -lglibmm-2.4 -lglib-2.0  -lstdc++ -lncurses -lflycapture   FrameRateCounter.o SaveVideoClass.o SaveVideo.o -o saveVideo   The compiling worked okay, but when linking it gave me a lot of undefined reference error:  FrameRateCounter.o: In function  `FrameRateCounter::FrameRateCounter(unsigned long)': FrameRateCounter.cpp:(.text+0x48): undefined reference to `Glib::Timer::Timer()' FrameRateCounter.cpp:(.text+0x58): undefined reference to `Glib::Mutex::Mutex()' FrameRateCounter.cpp:(.text+0x68): undefined reference to `Glib::Timer::start()' ... SaveVideoClass.cpp:(.text+0x1512): undefined reference to `cv::VideoWriter::VideoWriter(cv::String const&, int, double, cv::Size_<int>, bool)' SaveVideoClass.cpp:(.text+0x1541): undefined reference to `cv::VideoWriter::~VideoWriter()' SaveVideoClass.cpp:(.text+0x1565): undefined reference to `cv::VideoWriter::isOpened() const'  ... SaveVideoClass.cpp:(.text+0x2ea): undefined reference to `FlyCapture2::Camera::IsConnected()' SaveVideoClass.cpp:(.text+0x308): undefined reference to `FlyCapture2::Camera::Disconnect()' SaveVideoClass.cpp:(.text+0x30d): undefined reference to `FlyCapture2::Error::operator!=(FlyCapture2::ErrorType const&) const'   Then, I removed all the -llibrary flags, and it gave me exactly the same error messages. That's the reason why I think these flags didn't take effect. But why?  Here's some output of pkg-config if it helps:  pkg-config --libs opencv  -L/usr/local/lib -lopencv_stitching -lopencv_superres -lopencv_videostab -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_dnn -lopencv_dpm -lopencv_fuzzy -lopencv_line_descriptor -lopencv_optflow -lopencv_plot -lopencv_reg -lopencv_saliency -lopencv_stereo -lopencv_structured_light -lopencv_rgbd -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_face -lopencv_xfeatures2d -lopencv_shape -lopencv_video -lopencv_ximgproc -lopencv_calib3d -lopencv_features2d -lopencv_flann -lopencv_xobjdetect -lopencv_objdetect -lopencv_ml -lopencv_xphoto -lippicv -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_photo -lopencv_imgproc -lopencv_core   pkg-config --libs glib-2.0:  -lglib-2.0   pkg-config --libs glibmm-2.4:  -lglibmm-2.4 -lgobject-2.0 -lglib-2.0 -lsigc-2.0   If anyone wants to take a look at the source code, here is the .  Update:  The order doesn't seem to be the problem. Libraries are given before the objects, so they should be available to FrameRateCounter.o, SaveVideoClass.o, and SaveVideo.o

Why does the order in which libraries are linked sometimes cause errors in GCC?


My father Wilfred Charles Shortland served as Engineering Officer for the .  I am trying to find the ships when he was stationed in Malta in 1929-1934 and ships when stationed in Hong Kong or China in 1935-1939.

Are there any records for the Royal Fleet Auxiliary?   Albert George Adcock was in the RFA at Chatham about 1934 he was posted to Hong Kong and was captain of the Navy tug "Enticer". He was drowned at sea when the tug was sunk during a typhoon, 21st December 1946, and is buried in Hong Kong. I have not been able to find any information about his WWII service.


My Pokémon Go account has locked me out and I can’t enter. This has happened very recently. Unfortunately, if I sign up as a returning player, I need my username and password, which I forgot. I would be able to get back my username if I entered the player ID and screen name, but I have no clue on what these two words mean! I really need someone’s help!

So I had 20+ Pokemon on my account and today when I tapped on the app, it brought me back to the original screen when you first start playing. My friend who signed up tested using my username when she first started and my username was unavailable, meaning the account still exists. I don't have the password for the account, but I do have the email. So I wanted to know if it was possible to log back into an account?


Suppose $\alpha$ is a regular curve p.a.l. lying on a surface of a sphere centered at origin, i.e. $\left||\alpha(s)\right||=constant$, with $\kappa',\tau\neq{0}$. a) Show that if we write $\alpha(s)=a(s)\mathscr{T(s)}+b(s)\mathscr{N(s)}+c(s)\mathscr{B(s)}$, then $a(s)\equiv{0}$ for all $s$. b) Hence, or otherwise, show that $\frac{\tau}{\kappa}+(\frac{1}{\tau}(\frac{1}{\kappa})')'=0$  Here $\mathscr{N(s)}$ is the normal vector and $\mathscr{T(s)}$ is the tagent vector and $\mathscr{B(s)}$ is the binormal vector. Here are my thoughts:  Since $\left||\alpha(s)\right||=constant$, if we take the differential, then we get $<\alpha(s),\alpha(s)'>=0$ Since $<\mathscr{N(s)},\mathscr{N(s)}>=0$, $<\mathscr{T(s)},\mathscr{T(s)}>=0$ and $<\mathscr{B(s)},\mathscr{B(s)}>=0$, I am able to make the equation above easier, however, it is still unclear to me what to do next.  I am not sure whether my idea is right. Could someone help?

Let $r(s)$ be a curve parametrized by arc length, and $\kappa,\kappa',\tau$ are non-zero. Show that $r$ is a spherical curve iff $(1/\kappa)^2+((1/\kappa)'(1/\tau))^2$ is a constant.    The teacher gave the hint "center = $r+(1/\kappa)N+(1/\kappa)'(1/\tau)B$". I know how to get the proof from this, but how can we show that this is the center? Please help. Thanks.


If a question is closed or put on hold, usually nobody bothers to fix spelling mistakes in it. But if a new user does it, should the edit be approved? It does technically edit the post, although not in a way that could possibly lead to it getting reopened.  Basically the question comes down to "is that an appropriate way to gain reputation"? Do we trust users more because they can find poorly spelled questions and correct them? On the other hand, editing questions is often pointed out as a good way to get comment privileges and closed question are an obvious source for edit-worthy looking posts.

Should questions or answers on questions that are closed be edited, even if the question is closed and the edit does not change anything about the reason it's closed? Example:  was just edited, which I saw in the review queue. It certainly improves the answer, but since the answer doesn't really have to exist on SE at all (because the question is off-topic), should this edit be made? In my understanding, the only reason that the edit option for a closed question is not greyed out is so that it can be edited to make it comply with the SE rules.


Which tense should I use if for instance I'm talking about a curiosity and I want to ask if the person knew it?

I came across this sentence today in a wait screen for a twitter client:  Did you know that this wait is actually Twitter's fault, not ours?  Is "Did" correct usage in this case? I didn't know it earlier, but I became aware of it as I read it. Hence this seems logically correct. But a  Do you know that this wait is actually Twitter's fault…?"  sounds more natural in this case. What tense would be correct in this case?


I have AMD Athlon 2600+ (works on 1.9 GHz), 768MB DDR1 ram and Ati Radeon 9500pro 128MB ram. Can I run Ubuntu 12.04 or 13.04 on this configuration?

I'm thinking about installing Ubuntu Desktop, but I don't know what flavor is the best for my system. What are the minimum and recommended hardware requirements? What kind of CPU? How much memory? Should I have Hardware Acceleration? What flavor should I use?  This is an attempt of a canonical answer. My answers have the "official  requirements", the recommended are a mix of official sources and opinion based (along with the answer it's told the source). You can comment or edit if you feel that the information is obsolete or incomplete. It is a good rule of thumb that any system capable of running Windows Vista, 7, 8, x86 (Intel) OS X will almost always be a lot faster with any Ubuntu flavor even if they are lower-spec than described below.


Let $f$ be a real-value Lebesgue integrable function on $R$. Prove that  \begin{equation}  \lim_{t \to 0} \int_{R} |f(x+t) - f(x) | dx =0  \end{equation}    I have seen the proof of this using approximation theorem. Using the fact that continuous compact functions are dense in $L^1$. Now, I wonder if I can use the Dominate Convergence Theorem to prove this as well.   Since $f(x + t) - f(x)| \leq 2|f(x)|$ which is in $L^1(R)$ we then have  \begin{equation}  \lim_{t \to 0} \int_{R} |f(x+t) - f(x) | dx =  \int_{R} \lim_{t \to 0}|f(x+t) - f(x) | dx = 0 \end{equation}

I am having a hard time with the following real analysis qual problem.  Any help would be awesome.  Suppose that $f \in L^p(\mathbb{R})$, where $1\leq p< + \infty$. Let $T_r(f)(t)=f(t−r)$. Show that $\lim_{r \to 0} \|T_rf−f\|_{L_p} =0$, that is $$ \lim_{r\to 0} \left( \int_{\mathbb R} |f(t-r) - f(t)|^p \mathrm d t\right)^{1/p} =0.$$


I am trying to click a picture of an image projected by a projector with a Nikon DSLR camera. But whenever I click the picture there are weird colors all over the captured image? How can I stop that?   Thanks.

I was shooting in a gallery that used what appears to be a multi-colored projector and had difficulty shooting in that type of scene as the color was not even across the scene. The image shown below is what I mean, you see traces of green, blue, and yellow colors in the picture when it's supposed to be all white/gray as seen by the naked eye.  Why does this occur to the camera's output (DSLR or mirrorless) when shooting a scene that's lit by a projector? Is it the type of projector used? Is there a way to fix this or camera settings wise?


This is my first time writing codes in C# and I tried converting char data type ('2') to an int, float and decimal data type but I am getting a very awkward and unexpected result and I want to know why? Here is the code; using System; using System.IO; using System.Linq; using System.Collections.Generic;   namespace Practice {    public static class Program    {       public static void Main()       {          int number = (int) '2';          Console.WriteLine(number);          Console.Read();       }    } }  But instead of returning 2 like I expected, the console returns 50 and I am very very very confused right now! Some please, what's going on?

I have a char in c#:  char foo = '2';   Now I want to get the 2 into an int.  I find that Convert.ToInt32 returns the actual decimal value of the char and not the number 2.  The following will work:  int bar = Convert.ToInt32(new string(foo, 1));   int.parse only works on strings as well.    Is there no native function in C# to go from a char to int without making it a string?  I know this is trivial but it just seems odd that there's nothing native to directly make the conversion.


I'm new to React and try to create a simple integer input field that allows only numbers to enter. My code: import React, {useState} from "react";   export const IntegerInput = props => {      const maxLength = props.maxLength ? parseInt(props.maxLength) : 10;      const [intValue, setIntValue] = useState(props.value);      const inputMask = new RegExp(/^[0-9\b]+$/);      function handleChange(e) {         let inputValue = e.target.value;          let isNumber = inputMask.test(inputValue);         let isEmpty = inputValue === '';          if (isEmpty || isNumber) {             console.log('Update value to: ' + inputValue);             setIntValue(inputValue);         } else {             console.log('Invalid input: ' + inputValue);         }      }      return (         <input name = {props.name}                id = {props.name + '-id'}                type = "text"                className = {props.className}                maxLength = {maxLength}                value = {intValue}                onChange = {handleChange}         />     );  }  There is no error in the console and setIntValue is called only if needed but still can enter any character in the input field. What could be the problem? Please note, that I want to use "text" input and not "number" and I have the problem on the React side and not with the JavaScript.

Is there a quick way to set an HTML text input (<input type=text />) to only allow numeric keystrokes (plus '.')?


Let $G$ be a group of odd order, and let $H$ be a subgroup of $G$ of index $5$. Prove that $H$ is a normal subgroup of $G$. Hint: Show that there is no subgroup of order $15$ in $S_5$.  I did prove the hint, but don't see how it helps.

Let $G$ be a finite group and $H$ a subgroup of index $p$, where $p$ is a prime. If $\operatorname{gcd}(|H|, p-1)=1$, then $H$ must be normal. Does somebody have a quick proof of this?


Question about the practical use of super dense coding in information transmission: We know that by using super dense coding it is possible to transmit 2n classical bits transmitting n qubits, belonging to a set of 2n entangled qubits.  Problem is, it is necessary, before starting the transmission, to deliver n qubits to Alice and n qubits to Bob, entangled together. In my opinion this fact makes super dense coding of no practical interest because normally in a transmission system the sequence of information (classical) bits is of indefinite length and consequently the length n of entangled bits given to Alice (the transmitter) should be equally of indefinite length. Which is practically very difficult! Am I correct or am I missing something? Thanks.

When you enter the field of quantum communications, you run at some point into the concept of superdense coding.  Basically it is a way to encode classical bits on the qubits of a quantum channel, which sounds interesting in the first place to increase classical throughput by benefitting of the exponential growth of the Hilbert space with multiple qubits.  Yet when you look at the protocol in more detail, you understand that even though it seems that you have encoded 2 classical bits in 1 qubit, you actually need a second, entangled, qubit to retrieve the information from the 1st qubit.  So there is no real benefit - if you need to send two photons, you can encode two bits classically.  So apart from a textbook example, where is the practical interest? Are there more subtle points I am missing? Are there more intricatre protocols to avoid that?


Use the substitution $u = \frac{1}{x}$ to show that $\int_{0}^{\infty} \frac{\ln(x)}{1+x^2} dx = 0$    I know that this is improper and I could rewrite this as   $$\lim_{A\to0^+} \int_{A}^{1} f(x)dx + \lim_{B\to\infty} \int_{1}^{B} f(x)dx$$  Now I'm currently trying to figure out the integration of this  Using u = $\frac{1}{x}$, then $-du = \frac{1}{x^2} dx$. We also have $x = \frac{1}{u}$  $$= - \int\frac{ln \left(\frac{1}{u}\right)}{1+ \frac{1}{u^2}}\frac{1}{u^2}du = -\int \frac{\ln(\frac{1}{u})}{u^2+1}du$$  No idea how to do do this after that.

Evaluate $$\int_0^\infty\frac{\ln x}{1+x^2}\ dx$$ I don't know where to start with this so either the full evaluation or any hints or pushes in the right direction would be appreciated.  Thanks.


I have a file test with some data and I am using sed command to modify some word in the file and then redirect the output to the same file but after the command is executed the file contains no data. I don't get the reason behind that behavior?  $ cat test foo bar 123 bar foo foo $ sed 's/foo/bar/' test > test $ cat test $

Normally we use a different file to redirect the output.  For example :  cat < first > temp   In this command the contents of first are redirected to temp instead of the standard output.  Then why does it truncates the file if I use the same file name?  Why can't it overwrite the same file?  cat < first > first


Can someone please help me figure out the syntax to add the time to an output file's name?  I was able to get the date, but the time isn't working for me.  I keep googling it but so far I have come up empty.  I have figured out how to add it to the file itself, but I want to be able to see it in the name. The code below, is just a super simple robocopy command that I have saved as test.cmd. Everything works, everything except adding the time. Feel free to steal it if you want.  Just make sure you Google the switches so that you know what you're doing. That part is easy to find. My Code @ECHO OFF if not exist "C:\Example" mkdir "C:\Example" ROBOCOPY.EXE C:\Example Source "\\192.168.0.100\Shared Storage" /E /Z /J /NOOFFLOAD /R:2 /W:1 /REG /UNILOG+:"C:\Example Source\%date:~-10,2%-%date:~-7,2%-%date:~-4,4% Time.txt" /MT:4 exit

Update: Now that it's 2016 I'd use PowerShell for this unless there's a really compelling backwards-compatible reason for it, particularly because of the regional settings issue with using date. See @npocmaka's     What's a Windows command line statement(s) I can use to get the current datetime in a format that I can put into a filename?  I want to have a .bat file that zips up a directory into an archive with the current date and time as part of the name, for example, Code_2008-10-14_2257.zip. Is there any easy way I can do this, independent of the regional settings of the machine?  I don't really mind about the date format, ideally it'd be yyyy-mm-dd, but anything simple is fine.  So far I've got this, which on my machine gives me Tue_10_14_2008_230050_91:  rem Get the datetime in a format that can go in a filename. set _my_datetime=%date%_%time% set _my_datetime=%_my_datetime: =_% set _my_datetime=%_my_datetime::=% set _my_datetime=%_my_datetime:/=_% set _my_datetime=%_my_datetime:.=_%  rem Now use the timestamp by in a new ZIP file name. "d:\Program Files\7-Zip\7z.exe" a -r Code_%_my_datetime%.zip Code   I can live with this, but it seems a bit clunky. Ideally it'd be briefer and have the format mentioned earlier.  I'm using Windows Server 2003 and Windows XP Professional. I don't want to install additional utilities to achieve this (although I realise there are some that will do nice date formatting).


I imagine that at some optimum distance the gravitational waves would create compression and rarefaction waves in air sufficiently loud to be heard by the human ear. What is that distance? The previous reference given came up with a change in length of 1% at 2000 miles distance. That IMHO would be a planet wrecker. I am looking for a distance where the sound could just be heard.

Assume two black holes in the most common size range, spiraling into each other until they merge. The event releases significant amounts of energy via gravitational waves, which warp the space-time.  If the distortion is powerful enough, it would get noticed in daily life, or perhaps even detected by the proprioceptors in the human body.  How close, as an order of magnitude estimate, would you have to be to the merger to perceive it like that, without any instrument?


I know a moderator of stackexchange sites has some special Privileges to close a question as off topic. For example ,the following  question      on stackoverflow was put on hold by   a stackoverflow moderator with 21K reps, but he doesn't have a Golden badge or 1k votes on any of his answer related tags.    My question here is : Can He close my question my question as duplicate with mod privilegs?

Some people have a diamond after their username (e.g. )    What special privileges do diamond moderators have? How can I become a diamond moderator? Who are the diamond moderators?  How many are there?      For more information, see  in the .     Note: not to confuse with certain Stack Exchange employees, for example  members or "community managers", who often have diamonds as well, but are not ordinary moderators.


im having trouble understanding why this occurs: with the following code;      #include <stdio.h>      int main()      {         double x=123;          printf("x is %f. Enter a new value for x.\n", x);         scanf("%f", &x);         printf("x is %f\n", x);          return 0;     }   when you enter 45678 as the new value for x, 'x is 123.000017' is printed. I know that this is fixed when you use %lf when scanning, but why does this happen when using %f?

Why is it that scanf() needs the l in "%lf" when reading a double, when printf() can use "%f" regardless of whether its argument is a double or a float?  Example code:  double d; scanf("%lf", &d); printf("%f", d);


For example, what would it mean to say:     cd ~/mydirectory

I'm new to Linux and Ubuntu. People keep using ~/filename in their answers to my questions. What does ~/ mean?


I feel embarrassed to ask this, but I cannot link my small demo program to the xmlrpc-c libs. I know it should be obvious but I am stumped.  I have the same problem if I install the library via apt (Debian) or build/install from source (Debian or macOS).  xmlrpc.c:(.text+0x86): undefined reference to `xmlrpc_client_setup_global_const' xmlrpc.c:(.text+0xba): undefined reference to `xmlrpc_client_create' xmlrpc.c:(.text+0xf9): undefined reference to `xmlrpc_client_call2f' xmlrpc.c:(.text+0x166): undefined reference to `xmlrpc_client_destroy' xmlrpc.c:(.text+0x16b): undefined reference to `xmlrpc_client_teardown_global_const'   The command I used to compile link was gcc $(xmlrpc-c-config --libs --cflags client) xmlrpc.c  The output from xmlrpc-c-config is  -L/usr/lib/x86_64-linux-gnu   -lxmlrpc  -lxmlrpc_xmlparse -lxmlrpc_xmltok -lxmlrpc_util  -I/usr/include    This all looks good and the libraries are in the expected place.  I have tried the traditional remedy of repeating the library names on the command line e.g.  gcc $(xmlrpc-c-config --cflags client) xmlrpc.c   $(xmlrpc-c-config --libs client) $(xmlrpc-c-config --libs client)  but this has had no effect. I have also reviewed the answers in , but that does not seem to fix anything.   I have no idea what to try next (I have googled for all I'm worth, but to no avail)

Why does the order in which libraries are linked sometimes cause errors in GCC?


I have a Normal WCF Service and a WPF application that obviously calls data from that service. I have an issue now where a mobile web application came into play and also needs to call the same data on the same service, and with a little Googling I have seen with web application you will need to use a WCF RESTful to access the data. ( I can be wrong :) )  Can anyone advice me on what or how I can make my service so without changing any big chunk of coding in my WPF application and give access to data for the mobile application?

I have a WCF service and I want to expose it as both a RESTfull service and as a SOAP service.  Anyone has done something like this before?


Here's the difficulty:  If I put the eggs in a pot with cold water, then I can't reliably control how they cook. There are too many factors: amount of water, pot size, heat setting, etc.  If I put them in already boiling water, then I can get good results by controlling only the timing. The problem is that too often the eggs will crack from the heat shock.    I tried placing the eggs in warm water (from the tap) for 5 minutes so they wouldn't be fridge cold, and also laying them gently in the pot with a spoon, but sometimes they still crack. Is there a way to avoid this?

Sometimes when I cook hard boiled eggs they will crack in the saucepan, and some of the egg will seep out into the water.  Am I boiling the water too vigorously, or can I add something to the water to prevent it?


Let $F$ be a field and $p\in F[x]$ a polynomial. Then $\langle p(x)\rangle$ is maximal if and only if $p(x)$ is irreducible.  The proof goes as follow: Suppose first that $\langle p(x)\rangle$ is a maximal ideal $\operatorname{in} F[x] .$ Clearly, $p(x)$ is neither the zero polynomial nor a unit in $F[x],$ because neither $\{0\}$ nor $F[x]$ is a maximal ideal in $F[x] .$ If $p(x)=g(x) h(x)$ is a factorization of $p(x)$ over $F,$ then $\langle p(x)\rangle \subset\langle g(x)\rangle \subset F[x] .$ Thus, $\langle p(x)\rangle=\langle g(x)\rangle$ or $F[x]=\langle g(x)\rangle$. I don't understand from the factorization of $p(x)$, we can deduce the relationship between $\langle p(x)\rangle,\langle g(x)\rangle$ and $F[x]$

Let $R$ be a PID (Principal Ideal Domain) and $x$ is an element R. Prove that the ideal $\langle x\rangle$ is maximal if and only if $x$ is irreducible.   Ok, so I know what an irreducible is. I'm thinking that this problem is asking us to set up a proof by contradiction but I can't see how. No one in my study group has any clue.


I want that all \section, \subsection & \subsubsection entries that appear in the resulting pdf file are displayed with a sans serif font. I already tried to redefine the \section command as follows: \renewcommand{\section{}}{\section{\textsf{}}}. Unfortionately, this doesn't format. The reason probably is that I don't pass the argument of \section. How can I define the redefinition correctly? Francky @Leyn.eu

I would like to increase the size of pretty much every headlines, so that it is more prominent than the normal text.  I read about the  package, but can't seem to find good example how to use the package.  Using Gonzalo Medina does in fact change the font size, however, it changes the default font as well.  Before:    After:


I have the following sentence and I need your help:  "Renewable energy sources can contribute to achieving the climate goals" Is this correct or do I have to write: "Renewable energy sources can contribute to achieve the climate goals"  I'd appreciate every comment.

I'm trying to find, which of the following sentences is correct?  A) We try to highlight how they contribute to investigate their importance. B) We try to highlight how they contribute to investigating their importance.  I found that both cases were used frequently in formal writing. Edited: Sources for each case: For A: "Their multifaceted nature means that there are very many routes to investigating their importance for understanding social change" in "A lineage for contemporary inter-city studies" book. B: "More factors are analysed to investigate their importance in scoring from shots and shot probabilities" in "Applications of logistic regression to shots at goal at association football" book.


I have a player (who is a Bard/Rogue) who wants to fire both weapons but while I'm not seeing any rules against it I'm consulting for additional opinions.  Is there anything to consider when doing this?

The Sharpshooter feat includes an interesting feature: you can choose to take -5 penalty to hit with a ranged weapon attack to increase its damage by 10. Normally, I'd dismiss the trade-off as too situational, but I've only just thought of combining it with the Archery fighting style (+2 to hit with ranged weapon attacks).  After building a sample character using these features, the end result looks quite effective. My questions are: Is this build valid? Have I interpreted the rules correctly? If so, how well does it compare against other damage-focused builds?  5th level variant Human Fighter:   Ability Scores (via point buy): Str 10, Dex 16, Con 16, Int 9, Wis 12, Cha 10 HP: 47, AC: 17 (or 18 with disadvantage on Stealth) Weapons: Hand Crossbow x 2 Fighting Style: Archery Martial Archetype: Battle Master (with the Precision Attack maneuver) Feat (variant Human): Crossbow Expert Feat (4th level ability score improvement): Sharpshooter   The end result is a fighter capable of hitting targets 120' away, behind 1/2 or 3/4 cover, or engaged in melee with him, all without penalty. Normally, he can make 3 such attacks per round (Attack action + Extra Attack + Crossbow Expert's bonus attack). Once per short rest he can make 5 attacks per round via Action Surge (Attack action 1 + Extra Attack, Attack action 2 + Extra Attack, Crossbow Expert's bonus attack).  His normal attack bonus is +8 (3 proficiency, 3 Dexterity, 2 Archery fighting style), and normal damage is 1d6+3. Not amazing damage, but nice accuracy and flexibility (attacks can be focused on one target, or spread around; works equally well in melee and ranged combat).  The real winner is his ability to take -5 on any of these attack rolls to increase the damage by 10, to an average of 16.5 per shot (excluding crits). If he lands his usual 3 attacks, that's ~47 damage; 5 attacks is ~83. While the -5 to hit seems imposing, he's still got superiority dice: he can increase his attack roll by 1d8 after seeing the result, up to 4 times per short rest. And even without the superiority dice, his attack bonus is still an acceptable +3; ok for hitting low AC targets, or those granting advantage on attack rolls (e.g. surprised or prone + adjacent).  With a decent AC, a Fighter's HP, and the Second Wind feature, he can also take a decent amount of damage. He'll also have decent Strength, Dexterity, and Constitution saving throws.  This build seems almost too well rounded. Unlike a blaster, he only requires short rests to recover his big hitters. Unlike a brawler, he can target just about anything on the field at a moment's notice. Have I missed any rules, or overlooked any drawbacks?


Since  hasn't been picked up, I propose a different use of the page title.  Whenever "something" is updated on a question, the title should reflect the number of changes or at least that changes exist.  My motivation behind it is that I'm interested in the question itself when I browse SE. I want to keep the tab open and see if there are updates to the question without opening the tab.  It should be easy to implement since the updates are already coming in.    Proposed updates that should be counted:   Edit to question New answer Edit to an answer (if there are no answers yet, number of new comments)

After asking a question, I may be interested in quick responses and react on comments quickly. So I leave the tab open. But I always need to check back to the tab to see whether there's a "something has been added" note somewhere, either a comment to the question, or a new answer or a comment update on an answer I already read. Couldn't this also be shown in the page title so I don't need to switch tabs all the time while I'm reading something else?


I have an older Mac (2012 Mini) which I am expecting to replace, and use as a spare in another room. It came with OSX installed and has been updated through several OS versions to Catalina, which is the last supported version. I would like to totally wipe it and start over, changing hard disks at the same time. I don't really understand how MacOS licensing works, or how I can do a clean install. I don't want to find myself in the situation I have a Mac I cannot use to download/run an installer! What is the correct process?

Sometimes it's hard to search for older versions of macOS & OS X  on the App Store.  This is an attempt to provide the canonical QA for this issue, as per the Meta QA -  I expect it to be modified over time to hopefully become a complete information resource.  How can I get any older version of a Mac OS to be able to run as a VM, or to reinstall on my Mac?


I am trying to print an integer in  with commas as thousands separators. For example, I want to show the number 1234567 as "1,234,567". How would I go about doing this?   Here is how I am doing it:  function numberWithCommas(x) {     x = x.toString();     var pattern = /(-?\d+)(\d{3})/;     while (pattern.test(x))         x = x.replace(pattern, "$1,$2");     return x; }   Is there a simpler or more elegant way to do it? It would be nice if it works with floats also, but that is not necessary. It does not need to be locale-specific to decide between periods and commas.

I would like to format a price in JavaScript. I'd like a function which takes a float as an argument and returns a string formatted like this: "$ 2,500.00"  What's the best way to do this?


I want to add the row      ['2008',777,333]   to var fun and maintain the structure:  var fun = [     ['Year', 'Sales', 'Expenses'],     ['2004',  1000,      400],     ['2005',  1170,      460],     ['2006',  660,       1120],     ['2007',  1030,      540]          ];   Using push or concat seems to destroy the structure.  Can this be done?

How do I append an object (such as a string or number) to an array in JavaScript?


I have checked some post in this web but in this particular situation I am finding trouble with the negation. I have tried supossing by hypothesis that $\forall x. \phi$ but the contradictions of this does not mean $\forall x . \neg \phi$. I am also not sure at all of some notation. Once I have supposed something by hypothesis and got a contradiction, how should I justify what I have proved by contradiction in next line?  Thank you for your attention.

I am reading Velleman's "How to Prove it", and in one example he proves  $\neg \exists x P(x)  \implies \forall x \neg P(x)$    in the following way:    Suppose $\neg \exists x P(x)$. Let x be arbitrary. Suppose $P(x)$. Since we have a specific $x$ for which P(x) is true, it follows that $\exists x P(x)$, which is a contradiction. Therefore $\neg P(x)$. Since $x$ was arbitrary, we can conclude that $\forall x \neg P(x)$, so $\neg \exists x P(x)  \implies \forall x \neg P(x)$    What makes me confused is the line in bold text, that is "Suppose $P(x)$". The reason is that he writes that he is doing proof by contradiction, but $P(x) \not\iff \neg\forall x \neg P(x)$. He is not treating all possible cases where $\forall x \neg P(x)$ is false by assuming $P(x)$, does he? So how can this be a valid proof by contradiction?    Edit: I deleted my first example since it was clearly not representative for the problem.  Edit 2: So the thing that I am opposing I guess is that $\neg \forall x \neg P(x)$ is not $P(x)$. And from what I have undestood, a proof by contradiction should use the negation of the consequent which I do not think that Velleman does.


How to align objects in a constrain angle mode? a picture is worth a thousand words    maybe a plugin do the job?

I'm doing some isometric drawing in Illustrator, and moving my objects around on 0°, 30° and 60° constrained angles.  I keep having to go to preferences (Control + K) to change the constrain angle depending on how and where I'm moving something around.  Is there a quicker way to handle this?


my setup is the following:  TP-Link TL-ER5120 Gigabit Load Balance Router   The router has 2 WANs and 3 LANs connected to it:   LAN 1 Cable goes to a TP-Link SG-1024 Gigabit Switch (24 gigabit ports) LAN 2 Cable goes to a wireless router LAN 3 Cable 3 goes to a wireless router   So, my server is currently connected to the gigabit switch via 1 cable. The server is used by about 20 people for project management and ownCloud (file sharing).   Would it improve performance to add another gigabit ethernet card and connect it to the switch on another port?  NOTE: The load balancer sends all port 80 and 443 requests to the IP that the current network card has. If I add another card I wouldn't be able to redirect traffic from port 80 and 443 to it I think.

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?


Q. If $m$ and $n$ are two positive integers and $f:A\to A,$ where $A=\{0,1,2,3,...,m-1\},$ is defined by $f(x)= nx\pmod m.$ Find the condition on $n$ and $m$ which ensures that $f$ is one-to-one and onto.   My attempt: Here $f^{-1}$ must exist if $f$ is a bijection. Now as $f$ maps $x$ to $nx$ under modulo $m$ so $f^{-1}$ must map $x$ to $n^{-1}x$ under modulo $m.$ But in $\mathbb Z_m$(or here $A$), $n^{-1}$ will exist iff $\gcd(m,n)=1.$ So I think the required condition should be that $m$ and $n$ are relatively prime. (I don't know what the actual answer is!) I have just started with number theory and discrete mathematics this semester. So I don't have much knowledge to deal with such type of questions involving moduler arithmetic. So kindly guide me saying that whether my approach is correct or not. If not, please suggest me a way to reach the answer to this question or if it is correct, then can we reach the same conclusion using a different approach? I would love to know about your insights. Thanks in advance...

Say we have two integers $n$ and $k$, such that $0 < k < n$ and $gcd(n, k) = 1$.  Why is it that if we take every integer $x\in\{0,\dots, n-1\}$ and compute $k\cdot x \ (mod \ n)$, we get as remainders all numbers from $0$ to $n-1$, with no repeats?  In other words, why is $\ f:\{0,\dots,n-1\}\rightarrow\{0,\dots,n-1\}$, $\ f(x)=k\cdot x\ (mod\ n)$ a bijection for $k,n\in\mathbb{N},\ gcd(k,n)=1$?


I have a 3.3v line, which I will need to pull low intermittently with a microcontroller to send data.  I have tried using a BC547B NPN transistor (also tried BC337, BC517 and BD139) with the Collector connected to ground, the Base connected to a digital pin of the MCU (an arduino) and the emitter connected to the 3.3v line.  When the MCU needs the 3.3v line to be pulled low, it sends +5v to the Base of the BC547 so the emitter should be pulled low. When the 3.3v line can return to normal, the MCU sends LOW (0v) to the BC547. I have also tried adding a 1k resistor between the Base and the MCU.  What am I doing wrong?   (I know I can use an Arduino to pull the bus low, but I don't want to run the bus directly to the Arduino because it might get damaged)

I'm trying to make a simpler approach to flash LPC1114 MCU.  If the MCU is reset while pin1.1 is held low it enters bootloader mode. I'm using a simple arduino sketch to drive reset & 1.1 pins via serial line.  It was pretty simple with reset:         – Schematic created using   I've just replaced my button with a transistor and it did the trick.  Now, with 1.1 pin I have the following setup:          i.e. by default it's not connected to anything, on button press it's pulled down. Well, replacing the button with transistor doesn't seem to work.  Any hints on how to fix that?


When I click on the "profile" tab of a user profile, it leads to 500 error along with the "Oops! Something Bad Happened" error message.    The issue seems to be present on MSE, MSO, SO and a few other sites.

I can not currently visit user profile pages on any site I've tested. Activity pages work just fine.    Visiting anyone else's profile link fails† since links default to the profile tab unless you're looking at your own page or you're on a site you moderate but if you force the page URL to the activity tab, you can visit their activity page with no issue, so it's only the profile part of the page that's broken. For example:  Shog9's default link (this should time out):     Shog9's activity tab link (this should work):     This is currently happening again, same time of day, same day of the week, so I'm guessing there's something running that's causing the profile pages to not populate.   So, something running on Sunday between 4:00 and 5:00  Zulu time.    †: Oddly, some user pages work just fine... so it's not all of them. Found a few staff profile pages that loaded just fine but some non-staff pages also work.


I have just installed Ubuntu using ubuntu-16.04.4-desktop-amd64.iso. I had Endless OS on my lepton and I decided to overwrite it by Ubuntu.  Now, when I start my laptop, I first see "acer" logo, then, for a second I see a purple screen and then black screen.  What can I do to bring my new laptop back to the operational state?

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


In the early Action and Superman volumes, Superman is described as "Leaping over skyscrapers", and similar such terms. He is also portrayed as running from place to place, which begs the question, if you can fly, why run? Apparently he could leap over skyscrapers, but long distance air travel was something else again. The old TV show also began with "Able to leap tall buildings in a single bound".   Seems from all this that Superman didn't really "fly" - i.e. he had no scheme to give him lift, or any sort of propulsion system - he just made very long, strong (strong enough to reach escape velocity from the earth and much larger worlds as well), high jumps, and was able to navigate using aerodynamic principles - similar to a flying squirrel or fish, as opposed to a bird or bat.   Even though later on we find that he did travel long distances by air, couldn't we explain all of Superman's maneuvers as extraordinary powerful and carefully calculated leaps and bounces?  The proof would be from situations where he demonstrates acceleration without a boost from some external source of energy: If it's all leaping, even if it's incredibly powerful, he would be constantly decelerating to some extent.  Is there any proof that he could actually fly using some sort of propulsion system, like an airplane or a bird, and not just engage in mighty, calculated leaps? Would constraining Superman's ability to jump (hard to imagine how...) result in him not being able to "fly"?  This question is definitely not a duplicate. I am not asking how he flies, I am asking if he actually flies. See accepted answer, from before this question was mistakenly closed.

If I remember correctly, Superman's powers come from the fact that Earth's sun is yellow and Krypton's sun was red. So he is supercharged by our sun's solar energy or something like that.  While this could explain his strength, how does it explain how he flies?


I need to prove the following equality by induction: $$\left(\sum_{i=0}^nx^i\right)^{} =\frac{1-x^{n+1}}{1-x}$$ for every x except $$x\neq 1$$ Could anyone give me a hint about this? Thank you

$$\sum_{k=0}^nq^k = \frac{1-q^{n+1}}{1-q}$$  I want to prove this by induction. Here's what I have.  $$\frac{1-q^{n+1}}{1-q} + q^{n+1} = \frac{1-q^{n+1}+q^{n+1}(1-q)}{1-q}$$  I wanted to factor a $q^{n+1}$ out of the second expression but that 1- is screwing it up...


In bash, when I use Ctrl-R to retrieve a previous command, why does it not work when the command starts with a whitespace? Can I make it match such a previous command?  $  date Fri Nov 23 ... 2018 (failed reverse-i-search)` date': cd database/

If I perform a sequence of commands like:  $ ls $ grep abc file.txt   and then use the up arrow key to get the previous one, the terminal will show the last cmd (which is the grep here)  But if I do something like this:  $ ls $   grep abc file.txt   where grep is preceded by spaces, pressing up gives ls, not grep.  Why is this?


As in the past I installed Lubuntu but I installed a light one so many things weren't installed. Today, I noticed that when I use the up arrow key to retype the previous command, instead of showing the previous command as expected it just shows ^[[A. What could be the problem?

I have installed ubuntu minimal(mini.iso) on my vm. I then used recovery mode to login as root and create an account with useradd -m admin and then set a password with passwd admin.  When I login on the new account, instead of the normal prompt I only see a $ sign. If I try to tab-complete a command or file name it prints a normal tab. If I try to use the arrow keys it prints ^[[A, ^[[B, ^[[C or ^[[D. Also, ls no longer adds colors.  None of these problems were in recovery mode. How can I fix this?


I don't have any idea to solve this problem. Find the value of  $$\sum_{k=n}^{2n} \binom{k}{n} 2^{-k}$$  For every integers $n\geq1$  Could you give me a hint to solve it? Once I get a hint, I will try to solve it again. Thanks

Determine the value of $\displaystyle \sum_{k=n}^{2n} \binom{k} {n} 2^{-k}$ for $n \geq 1$  My attempt: I have asked this question before in another math forum but it leads no solution. My friend suggested me to search for something like series-k. I also looked at my textbook in combinatoric section (which apparently leads to Binomial Theorem), but really I don't have any idea for this one.  Could you help me?


I am using python3.9 and trying to calculate the following: 17.36-14.76. It is a pretty easy calculation and the output should be 2.6 without any other additional digits. However, in python3.9 I get the following output: >>> 17.36-14.76 2.5999999999999996  I know, I can round the result to get the desired output. However, I don't understand why it calculates it in a weird manner because 17.36-14.76 IS NOT 2.5999999999999996, 17.36-14.76 is 2.6. Are there some weird settings python?

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


Looking at Pascal's triangle, it looks as though all rational numbers can also be expressed as binomial coefficients. Given a rational integer, is it possible to calculate n & k for the binomial coefficient that will evaluate to it?

If I want to find how many possible ways there are to choose k out of n elements I know you can use the simple formula below:  $$ \binom{n}{k} = \frac{n! }{ k!(n-k)! } .$$  What if I want to go the other way around though?  That is, I know I want to have $X$ possible combinations, and I want to find all the various pairs of $n$ and $k$ that will give me that number of combinations.  For example, if the number of combinations I want is $3$, I want a formula/method to find that all the pairs that will result in that number of combinations are $(3,1)$ and $(3,2)$  I know I could test all the possible pairs, but this would be impractical for large numbers.  But perhaps there's no easier way of doing this then the brute force approach?


I just found this:    But it hides the entire input element. In my case, I'm using Django's form and there is text like "no file selected" or after you choose a file, the file name shows up. I want to keep those bits but customize only the button part of the input element.  See below for current approach.     But I want something like the styled one below but that retains the text in the previous images.    Is there a way to do this?  EDIT  I guess I should have been clearer. I saw all the other answers out there but my question is different. First of all, I know how to add attributes to the form class. I'm already doing this. Secondly, the images I attached were from my code. In other words, I already implemented the answers in the so-called duplicates.  My question pertains to the text next to the actual button that says "Browse". I want to style the button but KEEP the text, because this text is dynamic and changes with user action.  As far as I can tell, the other answers (and my assumption) is that the entire element gets styled with the custom CSS, so when it's hidden or obscured, the text is also hidden.  Given this, can anyone propose an answer?  Solution  Thanks to @lmgonzalves, I have realized that my problem was hiding the entire element. I should have just made a button overlay with the custom button like the accepted answer. Thanks again!

How do you style an input type="file" button?