I was reading  and came across this explanation:     By using mount -t iso9660 /dev/cdrom /media/cdrom, you tell the system: "take this very long string of bytes that you have in /dev/cdrom, interpret it as a directory tree in the iso9660 format, and allow me to access it under the location /media/cdrom"   and other answers along this line. This makes sense and from this logic, I understood that mounting essentially couples a filesystem to a device which interprets the contents of the device in a way that the kernel can fit it into the existing filesystem hierarchy.  If this is indeed the case, why is a loop mount needed?   Since a mount -o loop is technically identical to the operation mount is meant to do: read a file and interpret its content in the context of a filesystem, why can we not generalize the mount operation without creating a special device?  Edit: I understand that a loop device provides a block-device API to a file. My question is, however, more general. How is reading from a regular file (iso or similar disk image formats) different from reading from a special file, if they contain the same data?  My mental model of how mount works is this: given an arbitrary set of bytes exposed by a /dev/device file which are consequently interpreted by a filesystem driver (ext4, for example), the mount command associates it with the root hierarchy so that it appears transparent to the end user.  However, this arbitrary set of bytes can occur anywhere. If interpreted by a filesystem driver they should be recognized as a valid filesystem. What constrains a filesystem driver to read only from a special file and not a regular file?

I am mounting an ISO file, and looking at . They use the command:  $ mount -o loop disk1.iso /mnt/disk   I'm trying to understand the use of -o loop. I have two questions:   When I look at the long man page for mount, it takes time to find that -o option. If I do man mount | grep "-o" I get an error, and when I look in the file I do not find any info that "loop" is a command text for option -o. Where is that documented? Also, what is the "loop device" concept for mounting?


Does anyone here know how to print elements from the array one by one? I have this code here:   import java.util.ArrayList; import java.util.Iterator;  public class SimpleCollection {      private String name;     private ArrayList<String> elements;      public SimpleCollection(String name) {         this.name = name;         this.elements = new ArrayList<>();     }      public void add(String element) {         this.elements.add(element);     }      public ArrayList<String> getElements() {         return this.elements;     }      public String toString(){         String printOutput = "The collection "+ this.name+ " has "+ elements.size()+ " elements: ";         String e = "";         if(elements.isEmpty()){             return(printOutput+ " is empty.");         }if(elements.size()==1){             return "The collection "+ this.name+ " has "+ elements.size()+" element:"+ "\n"+ elements.get(0)+ "\n";          }             e = printOutput + "\n"+ getElements() + "\n";          return e;     }  }   The toString method of mine prints elements as an array: how can i print them one by one? Something like:  The collection characters has 3 elements: magneto mystique  phoenix

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 cannot find the JavaScript equivalent of PHP array_keys() / array_values(). For people unfamiliar with PHP given the following JavaScript hash: var myHash = {"apples": 3, "oranges": 4, "bananas": 42}  How can I get an array of keys, i.e., ["apples", "oranges", "bananas"]  The same question with the values, i.e., [3, 4, 42]  jQuery can be used.

I know in JavaScript, objects double as hashes, but I have been unable to find a built-in function to get the keys: var h = {a:'b', c:'d'};  I want something like var k = h.keys() ; // k = ['a', 'c'];  It is simple to write a function myself to iterate over the items and add the keys to an array that I return, but is there a standard cleaner way to do that? I keep feeling it must be a simple built in function that I missed but I can't find it!


I have sample string as below :  input - {"page":1,"per_page":10,"total":76,"total_pages":8,"data":""}  I want to filter out the total_pages as 8 in a sample Java program. For that I thought to build a regex to filter out substring as "total_pages":8,     Below is code .  **String regex = "/(.*total_pages.*?,/)"; String res =  "{\"(page\":1,\"per_page\":10,\"total\":76,\"total_pages\":8,\"data\":)"; System.out.println(res); System.out.println(Pattern.matches(regex,res));**   Please tell why It never matches with the substring.

I have several strings in the rough form:  [some text] [some number] [some more text]   I want to extract the text in [some number] using the Java Regex classes.  I know roughly what regular expression I want to use (though all suggestions are welcome). What I'm really interested in are the Java calls to take the regex string and use it on the source data to produce the value of [some number].  EDIT: I should add that I'm only interested in a single [some number] (basically, the first instance). The source strings are short and I'm not going to be looking for multiple occurrences of [some number].


How do I find sum of $\sum_{r=2}^\infty \frac{1}{r^2-1}$? The answer given in my book is 3/4. I can decompose the general term into $(\frac{1}{r-1}-\frac{1}{r+1})$ multiplied by 1/2 but since it is infinite I don't know what to do next. How should  I do this?


Colors like red and green are not visible to people with colour blindness.So is it a good idea to use red or variations of red as a user interface colour?

I want a green for "correct answer" and a red for "wrong answer". My current choice is rgb(144, 238, 144) for the green and rgb(250, 128, 114) for the red. (See wikilearner.net/wiki for the colours in action.)  I have been told that these colors are very close in contrast, making it difficult for a person with red-green color-blindness. What would be a better choice?


string = (input("Enter your own string: ")) if string == string[::-1]:   print("This is a Palindrome") else:   print("This is not a Palindrome")  I want this code to not care about lower or upper case please

How can I do case insensitive string comparison in Python?  I would like to encapsulate comparison of a regular strings to a repository string using in a very simple and Pythonic way. I also would like to have ability to look up values in a dict hashed by strings using regular python strings.


Just wondering. How can there have been one thousand avatars in the course of 10,000 years. Must have had pretty long lifespans.  Quote to back this up. Jeong-Jeong saying to Aang:      You Are Weak   Avatar Roku says     You think i am weak?   Jeong-Jeong says     No, no. I did not mean that   Avatar Roku says     I have mastered the elements a thousand times and now I must do it again. You will teach the Avatar firebending.   Jeong-Jeong says

If Avatar Wan lived 10,00 years prior to Korra's lifetime, then how many Avatars have there been?


I'm writing a Java code that would run a simple automation scenario in Chrome or Firefox - depending on the user's input. It starts running (opens a browser), but then throws java.lang.NullPointerException. I thought then the null I assigned the driver variable would later be overridden, but it isn't. How can this be fixed? Thanks!  package com.selenium;  import java.util.Scanner;  import org.openqa.selenium.By; import org.openqa.selenium.Keys; import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.chrome.ChromeDriver; import org.openqa.selenium.firefox.FirefoxDriver;  public class Main {      public static void main(String[] args) throws InterruptedException {         // environment variable         System.setProperty("webdriver.chrome.driver", "C:\\Automation\\libs\\Drivers\\chromedriver.exe");         //WebDriver chromeDriver = new ChromeDriver();         System.setProperty("webdriver.gecko.driver", "C:\\Automation\\libs\\Drivers\\geckodriver.exe");         WebDriver driver = null;          Scanner scanner = new Scanner(System.in);         int option = scanner.nextInt();         System.out.println("Please enter 1 for Chrome or 2 for Firefox " + option);         if (option == 1)         {             WebDriver driver1= new FirefoxDriver();         }         else if          (option == 2)         {             WebDriver driver2 = new ChromeDriver();         }         else              System.out.println("Please enter a correct number " + option);          String baseURL = "https://login.salesforce.com/?locale=eu";          driver.get(baseURL);          WebElement userName = driver.findElement(By.id("username"));         userName.sendKeys("Yan");          WebElement password = driver.findElement(By.id("password"));         password.sendKeys("123456");          WebElement rememberCheckbox = driver.findElement(By.id("rememberUn"));         rememberCheckbox.click();          WebElement bLogin = driver.findElement(By.id("Login"));         bLogin.click();          }      }

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?


During making of new variants performing steps. node edit form->add new variant->variant type ->panel->selection rules->node type->context continue->choose layout 2 column->continue->render->standard->continue after this white display occur,i am stuck here.what is the problem.

I have a issue with my Drupal installation, for example:   when I enable or disable the modules, It redirects me to a blank page, when I create a new content type and save it, redirects me to a blank page, when I add a new view and save it, it redirects me to a blank page, when I try to clear the cache, it redirects me back to a blank page, or in similar cases.   Basically all the confirmation pages redirect me to a white screen. When I refresh it again, it shows me the page. I tried to increase the PHP memory value but it doesn't help.  Are there any other solutions for this?  The error which I'm having:      Fatal error: Allowed memory size of 100663296 bytes exhausted (tried to allocate 8192 bytes) in sites/all/modules/views/plugins/views_plugin_localization_none.inc on line 1


I created an animation in blender, exported it as a series of png files, used the blender video editor to merge them as frames in a clip, and continued to add sounds, transitions, etc. to complete the scene.  When I attempted to export the final product to a video file, all of the frames were re-rendered, but instead of the correct color view they rendered as greyscale scene view (essentially not even rendering anything). All of the images were overwritten instantly, and the previous hours spent rendering were wasted.  Now, I'm trying my hardest to re-render the entire scene, but every time I try to render the animation (or even just a still image), it keeps rendering the greyscale image scene as opposed to the actual product. How can I fix this? Also, once this is fixed, what is the proper way to render the final video?

Blender is rendering an older version of my project, not the most recent one. I have made it using the Blender Render but it does not want to render in cycles either. A black and grey screen is rendered as if everything is transparent. Checked general camera, lighting and compute devises in case I messed something up but I can't find anything. All my textures and objects look normal, does anybody know what is wrong or what to check?  Ok added link:


I've been lurking Stack Overflow whenever I had a problem for at least the last 2+ years. More times than not, I find my solution (or cobble one together) before I get frustrated enough to have the innernets help me with my specific custom problem.  Many times, the only commentary I would be able to add would be "thanks!" which really only wastes bits and bandwidth.  I understand implementing measures to keep the bots and SEO kids out, but sometimes it's a PITA to start participating in a community.  If you couldn't extract my question from the above rant (or title), this might be a little more clear:  Why do I require 15 reps to just up-vote something?  I feel like it's kinda silly.  Additionally, I noticed the quote off to the left:     We prefer questions that can be answered, not just discussed.   yet I have looked around here and haven't been able to find any justifiable explanation.

I think more reputation points should be required to add a new answer than to upvote an existing answer.  I don't continually watch for new questions, so usually when I find a question it has already been answered.  It seems bit inappropriate to answer an already-answered question in order to contribute to the conversation, but until you earn reputation, you can't upvote or comment; you can only add new answers, which prevents me from contributing at the moment as much as I would like to.  This seems backwards to me. If someone incorrectly upvotes a bad answer, the damage is minimal, as other users can down vote it and upvote the correct answers. On the other hand, an incorrect answer wastes the time of everyone who reads it.  So, IMHO, it should require more reputation points to add an answer than to upvote or comment on an existing answer.  I wouldn't say say that users should be prevented from answering unanswered questions until they have x reputation points, as that might prevent users who have answers from providing them, but perhaps it should be required if the question is already answered, to discourage users from reiterating previously given answers.  What do you think?


My 5 year old pristine laptop decided to die. Every time I plug in the power it shorts the adapter so I think my motherboard is gone. Is it possible in anyway to boot into that install from another different Intel based laptop? Through a virtual machine? Or some sort of safety mode?  I know there is naturally a driver issue here but it's there any way to overcome it? I'm running fedora 25.

I know that it can, in some circumstances, be difficult to move a Windows installation from one computer to another (physically move the hard drive), but how does that work on linux? Aren't most of the driver modules loaded at bootup? So theoretically would it be that much of a hassle?  Obviously xorg configs would change and proprietary ATI drivers and such would have to be recompiled (maybe?). Is there more to it than I'm thinking of?  Assume the 2 computers are from the same era, ie both i7s but slightly different hardware.  Update: Thanks for the answers. This is mostly for my own curiosity. I have my linux system up and running at work, but eventually I'd like to move to a computer that I can get dual video cards into so I can run more than 2 monitors. But not any time soon


To have text and images on the same slide, I use this kind of code:  \frametitle{My title} \begin{tabular}{l} \parbox{0.5\linewidth}{ \begin{itemize} \onslide<2->{\item Item 1} \onslide<3->{\item Item 2} \end{itemize}} \end{tabular} \begin{tabular}{c} \only<2>{\includegraphics[height=3cm]{Image1}} \only<3>{\includegraphics[height=3cm]{Image2}} \end{tabular}   I'm pretty happy with the output, except for this small detail: even if Image1 and Image2 are the same dimensions in pixels, Image2 is slightly shifted to the right compared to Image1. Any idea how to fix this ?

I see that the code in many packages and examples contains percent signs % at the end of (many) lines. What are they used for? Do they affect the parsing of those lines?


I’m loading a JSON file a reading the values into an array using a for loop   I’m concerned that sometimes the JSON file might become corrupted ie the values Im reading in might become ASCII letters ie 1t3 where the value should of been 123   Is there a test case where you could say if values[a]  does not equal a number then set it to “   “ or blank   Thanks,  Ben

What's the cleanest, most effective way to validate decimal numbers in JavaScript?  Bonus points for:   Clarity. Solution should be clean and simple. Cross-platform.   Test cases:  01. IsNumeric('-1')      => true 02. IsNumeric('-1.5')    => true 03. IsNumeric('0')       => true 04. IsNumeric('0.42')    => true 05. IsNumeric('.42')     => true 06. IsNumeric('99,999')  => false 07. IsNumeric('0x89f')   => false 08. IsNumeric('#abcdef') => false 09. IsNumeric('1.2.3')   => false 10. IsNumeric('')        => false 11. IsNumeric('blah')    => false


When a user votes, but they have under the rep requirement. Upvoting - less than 15rep; Downvoting under 125rep - () They get this message:  Thanks for the feedback! Votes cast by those with less than 125 reputation are recorded, but do not change the publicly displayed post score.   My question is, where exactly are they "recorded"? What happens to them?

On many stackexchange sites I haven't enough reputation to cast an up-vote. Always I get the message "Thanks for the feedback! Votes cast by those with less than 15 reputation are recorded, but do not change the publicly displayed post score".  What does recorded mean exactly?    Can the owner of the up-voted question/answer see in any kind, that he/she got my up-vote? Does he/she get rep for this? What happens with these votes, if I reach the 15 rep? Will they take effect subsequently? Or are they just recorded for my "vote-history"?


Let k ≥ 1 be an integer and consider a sequence $n_1, n_2, . . . , n_k$ of positive integers. Use a combinatorial proof to show that  $\binom{n_1}{2}$ + $\binom{n_2}{2}$ +...+ $\binom{n_k}{2}$ $\le$ $\binom{n_1 + n_2 + ...+ n_k}{2}$   For each $i$ with $1 ≤ i ≤ k$, consider the complete graph on $n_i$ vertices. How many edges does this graph have?  Stuck on this problem and I don't know how to start. Was wondering if someone can point me to the right direction.


What is a regular expression for a positive integer? I need it in an if clause in a bash script and I tried [[ $myvar == [1-9][0-9]* ]] and I don't get why it says, for instance, that 6 is not an integer and 20O0O0 is.

I want to check if a variable has a valid year using a regular expression. Reading the  I understand I could use the operator =~  Looking at the example below, I would expect to see "not OK" but I see "OK". What am I doing wrong?  i="test" if [ $i=~"200[78]" ] then   echo "OK" else   echo "not OK" fi


A user in the comment section of  noticed that the question also appeared on another website:    Actually, it appears that this website is actively copying posts from Mathematica SO and pasting them there. Is there something that SE can do in such a situation?

of Stack Overflow, all content posted on Stack Exchange sites by their users (i.e. you wonderful people) has been provided to the whole universe under . For my fellow non-lawyers, that license basically means:   Anyone can use any Stack Exchange posts at any time without having to ask for permission Making money off of the copied content is permitted You don't even have to copy stuff from here verbatim; you can just use it as a starting point and make whatever edits you want There are just two rules you have to follow:   You have to provide . Simple links to the original post and author info are just fine. You have to  and allow other people to use your content, as long as they follow these very same rules. How meta!    (If you ever forget any of that, and want to refresh your memory, the license info is linked to in the footer of every page.)  There are, in fact, a lot of people who republish varying amounts of our content for assorted reasons. Unfortunately, there are some Stack Content Republishers Attributing Poorly and/or Excelling at Ranking (SCRAPERs, for short).  In this context, "attributing poorly" means any use that doesn't follow our attribution rules or make any other reasonable attempt at give credit. This can get pretty egregious; I've seen SCRAPERs that not only don't link back to SE originals, but also use fake author info and post dates to make it harder to find originals. By "excelling at ranking," I'm referring to copycat sites that end up higher in Google results than the original SE sites do for the same content. That's not necessarily wrong, but in some cases, it indicates inappropriate SEO hackery.  So, the question is: what can you do if you spot a SCRAPER?


I've heard that the $\alpha$ and $\beta$ parameters of the Beta distribution intuitively represent the number of successes and failures, respectively.   1) If so, what's the purpose of subtracting $1$ from them in the exponent?  2) If so, why would then $\alpha=1$ and $\beta=1$ represent a uniform distribution? Do we assume that there is one success and failure initially? Does this have anything to do with Laplace's Rule of Succession?  3) How can we intuitively understand positive real-valued shape parameters for the distribution?

Disclaimer: I'm not a statistician but a software engineer. Most of my knowledge in statistics comes from self-education, thus I still have many gaps in understanding concepts that may seem trivial for other people here. So I would be very thankful if answers included less specific terms and more explanation. Imagine that you are talking to your grandma :)  I'm trying to grasp the nature of beta distribution – what it should be used for and how to interpret it in each case. If we were talking about, say, normal distribution, one could describe it as arrival time of a train: most frequently it arrives just in time, a bit less frequently it is 1 minute earlier or 1 minute late and very rarely it arrives with difference of 20 minutes from the mean. Uniform distribution describes, in particular, chance of each ticket in lottery. Binomial distribution may be described with coin flips and so on. But is there such intuitive explanation of beta distribution?    Let's say, $\alpha=.99$ and $\beta=.5$. Beta distribution $B(\alpha, \beta)$ in this case looks like this (generated in R):     But what does it actually mean? Y-axis is obviously a probability density, but what is on the X-axis?   I would highly appreciate any explanation, either with this example or any other.


How is Yongnuo allowed to copy Canon, and why does Canon allow it? Does Canon see a significant loss in sales to Yongnuo?

Yongnuo has recently released their 50 mm f/1.8 lens that is almost identical to the Canon 50 mm f1.8 in their external design. They've also created a lot of clones of Canon flashguns and accessories like YN600EX-RT (Canon 600EX-RT) and the YN-E3-RT Radio Transmitter (ST-E3-RT Speedlite Transmitter) that are actually not that easy to tell apart from the Canon counterparts.  I guess that the patents regarding the 50 mm lens might be outdated, but the 600EX-RT was released in March 2012 so surely its protection must still be valid.  How can these products be legal to sell, and perhaps more important to photographers, are they legal to buy?  I realise that law may differ a lot between countries, but a general answer would be helpful too.


With the death of Chrome for 32-bit Ubuntu, is there a way to watch Netflix using Chromium?  The old Firefox/pipelight solution works, but performance is much worse than native Netflix on Chrome.  The solution at  has not worked for me.  Updating to 64 bit hardware is not an option for me at this time.

Just got the Firefox 49 update (yay!)  But Netflix still wants to install Silverlight (boo!)  How can I watch Netflix in Firefox, as ?


I have a piece of code here that theoretically should work, but in fact it doesn't.          Extras = getIntent().getExtras();     if(Extras!=null)     if(Extras.getString("startup")!=null)         StartUp = Extras.getString("startup");     else         StartUp = "0";      prefs = this.getSharedPreferences("runonstartup", 0);     start.setChecked(prefs.getBoolean("yesorno", false));      Toast.makeText(getApplicationContext(), "Start-up: "+StartUp+"\nChecked: "+String.valueOf(start.isChecked()), Toast.LENGTH_LONG).show();      if(StartUp=="1"&&start.isChecked())      {         new PostTask3().execute("testing");     }   The toast there shows: Start-up: 1 and Checked: true. Yet "if" fails to evaluate the expression as true and run PostTask3.  Help ... ?

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?


Q) $x^{2}+x+1$ is a factor of $(x+1)^{n} - x^{n} - 1$, whenever  (A) $n$ is odd  (B) $n$ is odd and a multiple of $3$  (C) $n$ is an even multiple of $3$  (D) $n$ is odd and not a multiple of $3$    My Attempt :- I don't know the formal approach to prove it. I have taken some small values of $n$ and I have eliminated options (A),(B) and (C) as :-  Here, I can rewrite $(x+1)^{n} - x^{n} - 1$ as :-   $[\binom{n}{0}x^{n} + \binom{n}{1}x^{n-1} + \binom{n}{2}x^{n-2} +......+\binom{n}{r}x^{n-r}+.....+\binom{n}{n-1}x^{1} + \binom{n}{n}x^{0}]  – x^{n} - 1$  $\binom{n}{1}x^{n-1} + \binom{n}{2}x^{n-2} +......+\binom{n}{r}x^{n-r}+.....+\binom{n}{n-1}x^{1}$  Now, if $n=3$ then it becomes $3x^{2} + 3x$. Since , $x^{2}+x+1$ does not divide it. So, $x^{2}+x+1$ is not a factor of $(x+1)^{n} - x^{n} - 1$ when $n=3$ , So, I have eliminated options (A) and (B)  Now, when $n=6$ then it becomes $\binom{5}{1}x^{5} + \binom{6}{2}x^{4}+\binom{6}{3}x^{3}+ \binom{6}{4}x^{2}+\binom{6}{5}x^{1}$ $=6x^{3}(1+x+x^{2}) + 6x(1+x+x^{2}) + 9x^{4}+8x^{3}+9x^{2}$.So, $x^{2}+x+1$ is a not a factor of $(x+1)^{n} - x^{n} - 1$ when $n=6$. So, I have eliminated option $(C)$.   So, I am getting answer as $(D)$ but I don't know how to prove it formally for all $n$=odd which should also not be multiple of $3$. Please help.

I have to find the form of n i.e. whether n is even or odd and whether it is multiple of 2 or 3 such that:  $x^2 + x + 1$ is a factor of $(x+1)^n - x^n - 1$  What I tried:  $$x^2 + x + 1 = (x + 1)^2 - x $$  also,  $$(x+1)^n-x^n-1= \binom{n}{o}x^n + \binom{n}{1}x^{n-1} + ... + \binom{n}{n-1}x + \binom{n}{n}.1 - x^n - 1$$  $$=\binom{n}{1}x^{n-1} + ... + \binom{n}{n-1}x$$  after getting this far I tried with taking x and n common but still couldn't able to find the right direction.  I need extra hints to solve this.


Suppose $\mathbb{F}$ is an infinite field. Define $p:\mathbb{F}\to\mathbb{F}^2$   as $p(t)=(p_1(t),p_2(t))$ where $p_1,p_2:\mathbb{F}\to\mathbb{F}$ are   polynomials.   Show that the image of $p$ lies in the zero set of some polynomial   $q:\mathbb{F}^2\to\mathbb{F}$.      (Bonus) Give a lower bound to the degree of $q$.   Any polynomial $q:\mathbb{F}^2\to\mathbb{F}$ of degree $D$ looks like $$q(x,y)=\sum_{0\leq i+j\leq D}c_{ij}x^iy^j\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;(1)$$ where $c_{ij}\in\mathbb{F}$. Now finding $q$ is solving the equation $$q(p(t))=q(p_1(t),p_2(t))=0.(2)$$ Plugging (1) in (2) we will have the equation $$\sum_{0\leq i+j\leq D}c_{ij}p_1(t)^ip_2(t)^j=0,\;\;\text{ for all }t\in\mathbb{F}.$$  Since this is true for all $t\in\mathbb{F}$ and the field is infinite, we can choose $t_1,t_2,\ldots,t_{N=\frac{(D+1)(D+2)}{2}}$ values for $t$ from $\mathbb{F}$ so that we get a system \begin{cases} \sum_{0\leq i+j\leq D}c_{ij}p_1(t_1)^ip_2(t_1)^j=0\\ \vdots\\ \sum_{0\leq i+j\leq D}c_{ij}p_1(t_N)^ip_2(t_N)^j=0 \end{cases}  So now we want to show that there exists those $t_1,t_2,\ldots,t_N$ that make this system not invertible. How to do that?

I have started working through the textbook Ideals, Varieties, and Algorithms by Cox, Little, and O'Shea and I am stuck on one part of an introductory question.  The question begins by getting one to show   (1) If $f(t)$ and $g(t)$ are polynomials of degree $\le n$ in $t$, then for $m$ large enough, the monomials  $$[f(t)]^e[g(t)]^f$$ with $e+f\le m$ form a linearly dependent set in $k[t]$.  The next part of the question asks one to deduce      (2) If $C\,:\,x=f(t),\,y=g(t)$ is any polynomial parametic curve in $k^2$, then $C$ is contained in $\textbf{V}(F)$ for some $F\in k[x,y]$.   I have demonstrated (1), but I am at a loss as to how to use that fact to prove (2). It doesn't seem like it is supposed to be a hard problem, but never the less I am having trouble wrapping my head around it. Additionally I assume that for (2) we are not interested in the trivial solution $F=0$.  [Added for completeness]  To do part (1), we recognize that if $\deg(f),\deg(g)\le n$, then $$\deg\left([f(t)]^e[g(t)]^f\right)\le ne+nf\le nm$$ Hence if we have more than $nm+1$ polynomials of the form $[f(t)]^e[g(t)]^f$ then we have a dependent set (since $d+1$ is the dimension of the vector space of polynomials of degree less than or equal to $d$). Now we simply count the number of polynomials in this form (this was an exercise before the problem) - it is $\binom{m+2}{2}=\frac{1}{2}(m+1)(m+2)$ from a standard application of . Ensuring $m$ large enough (specifically $m>2n-3$) gives us the conclusion.


I have a expired Indian Passport with a Valid US Visa in perfect condition. Due to some unfortunate event the old US Visa(expired in 2015) on the expired Passport got smudged and now looks a bit faded. Is the expired Passport now invalid, and so is the Valid US Visa which in perfect condition?  Do I need to get the Visa re stamped on the new Passport?   Thanks.

I have a valid B1/B2 US visa expiring about a year from now. The passport it's in expired a few years ago, and I recently got a new one.   The passport number does not match, but the national ID number, mentioned in both, does (it used to be the same as your national ID, but not anymore)  Can I travel to the US carrying both passports? Or is it asking for trouble? (I read a few years ago that it was possible, but that might have changed)  Should I just get a new visa to avoid potential complications?


I have been trying to write a Python script that uses global variables. I am getting what seems to be unexpected results in my code. Instead of dumping all the code here, I have created a small piece of code to show what I'm seeing.  def func1():     global aaa     aaa = 1  def func2():     while aaa < 5:         print(aaa)         aaa += 1  func1() func2()   I am expecting to get,  1 2 3 4   What I get instead is,  Traceback (most recent call last):   File "test2.py", line 11, in <module>     func2()   File "test2.py", line 6, in func2     while aaa < 5: UnboundLocalError: local variable 'aaa' referenced before assignment   If I change func2 to remove the while loop & just print the aaa variable, it works fine, so the global variable is accessible.  def func1():     global aaa     aaa = 1  def func2():     print(aaa)  func1() func2()    Running it produces,  1   If I set the aaa value at the top of func2 it also works.  def func1():     global aaa     aaa = 1  def func2():     aaa = 1     while aaa < 5:         print(aaa)         aaa += 1  func1() func2()   Which results in,  1 2 3 4   I have experience with Perl, but am new to Python. Is there something that I'm missing here?

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


Back in the day, when SO Documentation was in its beta phases and had its own meta site, I registered and added it to my sites on the android app. I just noticed it appears as "Unknown Site docs-beta":         I'm guessing the same behavior would reproduce with any closed site (such as failed betas), although I can't think of a way to test this theory at the moment.  System details:   App version: 1.0.89 Android version: 5.1.1 Phone model: Nexus 4   P.S. IMHO, this is a bug report on the android app, not a documentation specific question. If the mods, disagree, please migrate it to MSO.

Recently I was in the private beta for Game Theory, however it didn't take off and the site was closed down. When the site was closed, it was automatically removed my from my favorites in the drop down menu on the desktop version. The android app however did not remove it from the favorites and now is reporting it as an unknown site. It seems like the site should have been removed from the desktop and android versions at the same time.  When I went in to edit the pinned sites on my android app they did not appear and were gone when I canceled. So the app will correct itself but you must go in to attempt to edit first.


My system:  Ubuntu14.04  Linux version 4.4.0-144-generic (buildd@lgw01-amd64-023) (gcc version 4.8.4 )  I try to change the login procedure to realize a function that a NULL string and my password can both login in Ubuntu.Some web info suggest me download util-linux-2.13-pre7.tar.bz2 and remake the login.c.But when I make the login.c(in util-linux-2.13-pre7/login-utils/),there is a error:  /usr/include/time.h:192:15: note: expected ‘time_t *’ but argument is of type ‘int32_t *’  extern time_t time (time_t *__timer) __THROW;  I have google this error and knew that is a 32bit/64bit linux bug.So I doubt that the login.c in util-linux-2.13-pre7.tar.bz2 is not suitable for Ubuntu14.04.   So my question are :   1.If the util-linux-2.13-pre7.tar.bz2 is not suitable for Ubuntu14.04,which version is suitable for Ubuntu14.04.   2.Could I change the login procedure through remake login.c?

I am assuming that all application installed through apt-get are open source; but for those that are available in that manner, where can I get the source code for these applications as well as update them?   I have a couple applications I use regularly that aren't being actively developed any longer and I would like to add features. Where would I go to get the rights to update these applications?  In this case specifically, I am referring to the hellanzb package


what is the right way to say?  "combat sports lesson" (sports with s) or "combat sport lesson"?  It should not mean a specific style of combat sport like wrestling or karate.  It should mean combat sport in general.  Thank you.

Sorry for the title, it is not very evident and intuitive but I really do not how to tell it better...  Well, you know, several times, or better, many times, we use this form:  If I want to say:      "development of special weapons was   the first point in Hitler's   program..."   I will say this (a better form):      "special weapon development was..."   OK...  is it      "special weapon development"   or      "special weapons development" (note   the plural...)   what's the grammar rule in order to understand how to use this very used form?


My directory structure:  root\bin\run.sh \\main shell file i am trying to write root\folder1\script.py   root\folder2\script2.py  So, I want to execute run.sh (from anywhere).. and then first execute   python root\folder1\script.py  python root\folder2/script2.py   But, I don't want to give the full path.. as that might change (depending on which system, I am running the code...) but the relative paths between run.sh script.py and script2.py will not change.. So, how do i do this in shell?

How do I get the path of the directory in which a  script is located, inside that script? I want to use a Bash script as a launcher for another application. I want to change the working directory to the one where the Bash script is located, so I can operate on the files in that directory, like so: $ ./application


This happened within the last hour or so on Mi Yodeya:      The achievements drop-down is similarly affected.  This happens on every site I've tried (responsive or old design, with or without an account) except for Meta.SE, which has the correct icons.  I see that some (but not all) HNQ icons in the right column are also affected, but haven't looked for a pattern there.  I know that "meta is different", but this isn't the kind of "different" we usually see.

I see the same problem has occurred in the past, the most-linked one being   Is this happening for anyone else?   I've marked the icons I could recognize as incorrect.  This exists on every page, is on both chrome and firefox (from Ubuntu 16.04), and persists after hard-refreshes in each.  Edit: The icons in Meta's Hot Network Questions tab appear to be consistently accurate. Every other page I checked (including Unix, Workplace, English Language & Usage, Money, and Sci-fi) have a handful of incorrect ones, even for some of the same questions that are displayed correctly in Meta.  Further note: if it matters, the icons are also incorrect in the drop down community-search feature on the right end of the header. Again, they appear correct on this Meta page, and incorrect on all other pages I've checked. Some of the ones that are consistently incorrect:   computational science constructed languages movies and TV raspberri pi rpg russian language science fiction and fantasy sitecore skeptics super user latex workplace   That distribution seems skewed, but I may just be disproportionately familiar with the sites at the end of the alphabet. Many others could be wrong, those are just the ones I could recognize.    Last edit: apparently my Google skills were lacking -  was asked an hour prior.


Let $A, B$ - sets such that $A \setminus B$ is infinite, $B$ - finite. Proof that $(A \setminus B) \sim A$

A is a finite subset of S, which is an infinite set.  How can I prove that $|S| = |S \setminus A|$?  I just finished proving that $|T \cup S|$ where $T$ is infinite and $S$ is countable is $|T|$. They seem related but I can't solve it because I am confused by the concepts.  Can someone help me?


I use this html code and it works well. The button can be clicked and change a page like I want to.

          #id	          name	          info

       1	       jui co.	       <button style="background-color: #FAF0BA; color:#00CCA5;" data-role ="button" data-mini="true" data-inline="true" data-icon ="info" class="info" value="1">info</button>

   now i want to add id and name into sqlite database. After i add i wan to show is under div id="my_data" using$('#my_data').empty().append(). my code that append is the same as code i use above.  function renderList(tx, results) {     var htmlstring = '
\n';      htmlstring += "
\n";     htmlstring += "

\n";     htmlstring += "
\n";     htmlstring += "#id	\n";     htmlstring += "name	\n";     htmlstring += "info	\n";     htmlstring += "
\n";     htmlstring +="
\n";     var len = results.rows.length;     for (var i = 0; i < len; i++) {         htmlstring += "
";         htmlstring += "" + results.rows.item(i).cid + "	";         htmlstring += "" + results.rows.item(i).name + "	";         htmlstring += "<button style=\"background-color: #FAF0BA; color:#00CCA5;\" data-role =\"button\" data-mini=\"true\" data-inline=\"true\" data-icon =\"info\" class=\"info\" value=\"" + results.rows.item(i).cid + "\">info</button>	";         htmlstring += "
";     }       htmlstring +="
";       $('#my_data').empty().append(htmlstring); }   It shows on screen but is look like when I did't import jquery and jquery mobile (which I did and it works well on the first code) and went I click the button, it doesn't work. It look like it isn't loading jquery and jquery mobile. It looks the same when I remove jquery and jquery mobile import and run the first code. How to make it work?  ps.my click code.  $(document).ready(function () {     $(".info").on("tap",             function () {                 document.location.href = "./customer_info.html" + "#id=" + $(this).attr("value") + "&name=" + uid;             }); });   --------------------------update1------------------------  i try the code below but it still don't work  $(document).ready(function () {     $('#my_data').on("tap",".info",             function () {                 document.location.href = "./customer_info.html" + "#id=" + $(this).attr("value") + "&name=" + uid;             }); });

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


It's a time cost heavily job when compile something on server. But, my VPS ssh connection is unstable. Connection will be lost in about 10 minutes. How can I let my command continue run when ssh connection lost ?

I'm working on a Linux machine through SSH (Putty). I need to leave a process running during the night, so I thought I could do that by starting the process in background (with an ampersand at the end of the command) and redirecting stdout to a file.  To my surprise, that doesn't work. As soon as I close the Putty window, the process is stopped.  How can I prevent that from happening??


I have fixed many 404 pages on the site, and added a few blogs with deep links, and some good authoritative backlinks, but it is still not ranking. Tried submitting to webmaster, added some fundamental SEO apps, but worried this is going to take a year to come back to life because of the 404s that I had. Any ideas on what could be the problem. I have tried literally everything, the URLs are canonical, etc.. still issue... I use to have  really high ranking bog, but I hosted it on a different site, and forwarded my blog links to this other site, then I thought traffic would be higher if I matched everything over to the same site, but appears this was more of an issue,

There has been a significant drop (90%) in traffic from Google to one of my well-established sites (6+ years) in the last week. Searches show that the top 3 wide keywords all dropped 4 spots. Searches for other keywords do not show ANY results in the first 10 to 25 pages of results, while previously one 1st or 2nd page at most.  Since there are , the question really is:  What steps are necessary to figure out what caused such a drop?  There have been no major changes during this period or the last month on the site and certainly not in the homepage which has dropped in rank. Over all the years of running this site and plenty of others, I have never experienced this. There are is duplicate content on my site and I have rigorously used canonical links for the last few years to ensure it is not misinterpreted as such.


How can I prove this: $$a^x\times a^y=a^{x+y} $$ when $card(A)=a$ , $card(X)=x$ and $card(Y)=y$.

Let $A,B,C$ be sets, and $B \cap C=\emptyset$. Show $|A^{B \cup C}|=|A^B \times A^C|$ by defining a bijection $f:A^{B \cup C} \rightarrow A^B \times A^C$.  Any hints on this one?  Thank you!


I want to delete a file but it cannot be deleted because is used by another program. how can I find the program which is using this file? I've seen task manager but there is nothing there to find out it!  I'm using windows 7.

On Windows XP, when I try and delete a specific file it says:     Cannot delete blah.blah: Make sure the   disk is not full or write-protected   and that the file is not currently in   use.   How can I go around this warning and delete it anyway?


I have got this weird bug were my number is really long like this:    I think it is so because i get it from a label.  Double(lblsSteppers[i].0.text!)!   I also seems to happen to only certain numbers like 9.2.  But i don't know a way to prevent it. So does anybody also else have encountered this? And what have they done to prevent it.  Update:  The error that i got is floating-numbers of some sort. So now somebody suggest to format the numbers for viewing them. But how can i do that?

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


I need to use the 'checked' option in a radio button, but I want to use it dynamically. That is, either the right or the left button is pre-checked based on data from a database and the user can choose to accept or change it. To do this, I need the String "checked" as part of my radio button tag. I created two variables, chekR and chekL, with the plan that one of them would evaluate to "" while the other would evaluate to " checked". However, my IF condition fails to do the job. The value Right or Left comes from a form, and I tried printing it, which works fine, but the actual comparison is failing.  The variable passed from the form is stored as String D. If I try evaluating (D == "Right"), it returns a false every time. I tried two IFs (see code), I tried IF-ELSE, but no success.  String chekR = ""; String chekL = ""; if(D == "Left") { chekL = " checked";} if(D == "Right") { chekR = " checked";} <form action = update3.jsp>
 <input type="radio" name="PtEye" value="Right" <%=chekR%>>Right <input type="radio" name="PtEye" value="Left" <%=chekL%> required>Left
<input type="submit" value="Confirm"><input type="reset" value="Restore to original"></form>   I need the expression <%=chekL%> to produce either a blank or the word checked, depending upon the value of D.

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


I'm having trouble about understanding id in Python3. I always thought holding same value means pointing to same address until i got output like this :  >>> a = 1000 >>> b = 1000 >>> id(a) 140241096743312 >>> id(b) 140241096274640 >>> id(1000) 140241096274800 >>> c = 5 >>> d = 5 >>> id(c)  == id(d) True   Why am i getting different addresses ? What makes 1000 special or different from 5 so that variables point different addresses ?

Why does the following behave unexpectedly in Python?  >>> a = 256 >>> b = 256 >>> a is b True           # This is an expected result >>> a = 257 >>> b = 257 >>> a is b False          # What happened here? Why is this False? >>> 257 is 257 True           # Yet the literal numbers compare properly   I am using Python 2.5.2. Trying some different versions of Python, it appears that Python 2.3.3 shows the above behaviour between 99 and 100.  Based on the above, I can hypothesize that Python is internally implemented such that "small" integers are stored in a different way than larger integers and the is operator can tell the difference. Why the leaky abstraction? What is a better way of comparing two arbitrary objects to see whether they are the same when I don't know in advance whether they are numbers or not?


The energy lost on charging a capacitor can be easily found from the change in energy of the components of the circuit and the energy supplied by the battery. On charging a capacitor I know that the energy loss appears as heat in the internal resistance of the battery and the wires. But what if I take (Purely theoretically) a battery with 0 internal resistance and wires with 0 resistance? I can't see why the capacitor won't be charged, so from the calculation there must be energy dissipated in the circuit. So in that case, where is the heat dissipated? Or is this ideal case faulty?

For a simple circuit with a battery supplying a voltage $V$ to a capacitor, let us assume that the charge on the capacitor is $Q$. Now, the work done by the battery or the energy supplied is given by the relation:  $$W=QV$$  But the energy stored in the capacitor is given by:  $$U = \tfrac12 QV$$  The value of $Q$ as well as that of $V$ should be the same in both the equations.  Now my question is, where is the other half of the energy that the battery supplied?


I installed prime-indicator, which allows to quickly switch between Intel and Nvidia graphics cards, as reported here:    No problems with Unity or Gnome Shell, but here what happens in xfce4 environment, with the appindicator plugin:    How to solve?

I have strange problem. My Wallch icon is huge. See the screenshot:    I removed XFCE settings and reordered items a little. How can I restore normal Wallch icon size?  Update:  My /usr/share/applications/wallch-nautilus.desktop file:  [Desktop Entry] Version=4 Name=Wallch Comment=Change desktop wallpapers automatically Exec=/usr/bin/wallch %U Icon=wallch Terminal=false Type=Application Categories=Utility;Application; MimeType=inode/directory;  Actions=Change_Wallpaper;Start;  [Desktop Action Change_Wallpaper] Name=Change Wallpaper Once Exec=/usr/bin/wallch --change TargetEnvironmet=Unity  [Desktop Action Start] Name=Start/Stop Wallpapers Exec=/usr/bin/wallch --start TargetEnvironment=Unity   And the /usr/share/pixmaps/wallch.png:


I have Ubuntu 13.04 installed on a Gigabyte BRIX and serving as a HTPC (plugged into my television through a HDMI connection)  My question is pretty simple, is it possible to start Ubuntu without the Unity desktop and still be able to launch graphical applications such as XBMC ?

I want to do a small computer just for internet browsing. I dont want to load a desktop environment to keep RAM, CPU and GPU ussage as low as possible. The computer is going to run on a ARM CPU. I dont care with Distro I use, I thought about good old plain Debian.


Let $a_1,a_2,a_3,a_4\in\Bbb R$ such that $a_1+a_2+a_3+a_4=0$ and $a_1^2+ a_2^2+ a_3^2+ a_4^2$ = 1. Then find the maximum value of the expression $(a_1-a_2)^2 + (a_2-a_3)^2 + (a_3-a_4)^2 + (a_4-a_1)^2$   question has been asked here before, however previously only the minimum value was asked. For $a_1=\frac{1}{2}, a_2=\frac{-1}{2}, a_3=\frac{1}{2},a_4=\frac{-1}{2}$ the expression is $=4$ and I can see that this is probably the maximum. However I can't think of how to prove it. Any hints will be appreciated, thanks


HIV spreads only through body fluids. If a mosquito bites an HIV infected individual and then an uninfected individual, will the virus spread  to the new individual?

It is known that HIV is usually transmitted by direct blood or body fluid contact between an infected individual and a healthy person (like blood transfusion or needle sharing):  Suppose a mosquito bites an individual suffering from AIDS and in the process sucks up some T cells infected with HIV along with RBCs. Then it bites another person not suffering from the disease, and transfers these infected T cells. Isn't there a high probability of the second individual contracting HIV?


Using natbib together with hl or st from soul (or soulutf8) produces Argument of \@citex has an extra }. [{\st\cite] errors, as already mentioned in .  While a solution is to wrap all the \cite commands with an additional pair of curly brackets, or when this fails with \mbox, this solution may not be very convenient.  Consider in particular the situation in which we have a document, in which for some reason we are forced to use natbib for the references (like what happens when using revtex document classes). We have lots of text with lots of \cite in it. We want to define a command \remove that highlights text to be removed, with something like \newcommand{\remove}[1]{{\color{red}\st{#1}}}.  To use this command in blocks of text containing lots of \cite can be very annoying, requiring to wrap all of them with brackets or \mbox. Is there a way to define a "smarter" command that can be used over \cite without modifying the original text?    A MWE of the problem of using \hl and \cite together is already given in the linked question, but I'll include another just for completeness:  Tex file:  \documentclass{article}  \usepackage{soulutf8} \usepackage{natbib}  % how can I more smartly define this command, to use it to wrap text containing \cite{...}? \newcommand{\remove}[1]{{\st{#1}}}  \begin{document}  \remove{\cite{foo}}  \bibliography{bibliography} \end{document}   bibliography.bib:  @article{foo,  author = {SomeGuy},  journal = {Somewhere},  title = {Foo} }

The soul package provides a useful command \hl for highlighting text. However, \cite, \ref, and some other commands (maybe equations too) must be placed within an \mbox in order for \hl to work properly.  Is there any way to make this automatic? Meaning that to modify \hl (and other commands provided by soul) to put everything except plain text in an \mbox?  \documentclass[12pt]{article} \usepackage{soul} \begin{document}  \section{1}\label{sec} This is to show that \textbackslash{hl} fails to highlight texts containing citations or reference!  \hl{ This is one line containing a citation \mbox{\cite{}}}  \hl{ This is one line containing a reference \mbox{\ref{sec}}}   \end{document}


Here a beginners question.  Is there any difference in JAVA between passing an object as argument to a method or returning that object from the method. For instance: Is it better to pass a List as an argument and fill it in the method or just allow the method to return a list?  My guess is that it should be no difference since a reference is returned and nothing is copied. But is there something more subtle behind?  thanks in advance  Altober

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


How do I check to see if a cell contains a phrase from a defined range of cells?  I have a column filled with keywords, if one of the keywords is mentioned in a Column A, I want Column B to display FALSE, otherwise TRUE.

I want to check if the value of a cell exists in a range of cells. How can I do this?  Just like you would be able to do "if value in list_of_values" in Python for example.


I have 10 months of work, which's my first work experience, and during this period I haven't saved anything in my bank account. I spend all of my salary on rent, which represents 32% of it and the rest in the daily expenses. I want a way to keep as much money as possible because I really need it to do many things.

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


My Windows 10 boots very slowly. At startup it remains stuck on the boot image with no hard disk working for 1-2 minutes; after that it starts normally.   I've already checked if I have "fast boot up" option active, but I don't have that option.   So my question is: how to find what program/service causes this lag?

In august 2015, I have upgrade my laptop from windows 8.1 to windows 10. But it spends always 10 minutes to boot it. It is not normal that it spends so long. What can I do for boot him faster? Below some information about my laptop.   age: +/- 2 year (on august 2015) edition: Windows 10 Home   File trace are removed.  Update:    I must also say that always there comes a windows update, I have the same problem again form slow booting. Is it good that I turn off the updates? If yes, how can I do that? Also it is in periods that my pc booting to slow. Some time it is like normal (a few seconds) and other times a few minutes. I don't know how it comes that it is fast or slow.


I use windows 7 and every install I've ever had starts to start up really slow after several months of use. Instead of trying to speed it up (like I already did with pretty much every widespread tweek out there), I want to know what is slowing down my windows 7 startup. It goes a good minute after the logon screen, with nothing running, with 0% - 1% CPU usage and only after that period of time it opens the programs that I've already clicked, which leads me to believe there's something deliberately delaying my programs initialization and I want to know what

When I start my PC, it boots into Windows (Windows 7 32-bit) quite happily, I login and the main Windows screen appears. At that point, however, the system is extremely unresponsive for up to 5 minutes - if I click on Firefox to start it, nothing appears to happen for a long time, etc, etc. The mouse and Windows UI is responsive, but programs take forever to start, webpages seem to hang (or at least load extremely slowly) and so on.  I imagine that the issue is with one or more programs that run on startup, but I don't know quite how to identify which one it might be. The event log shows nothing of any obvious interest. I can't see any high CPU activity in task manager or Process Explorer, and I can't hear any high disk activity.  I'd rather understand what's happening and then work out how to address it, than have to go for a blind "switch things off and see what helps" approach, but maybe that's being optimistic :-)  I suspect disk bottlenecks or network, but I don't know how I could set something up to diagnose this (and in particular, given that I can't get programs to start in a timely manner, I'd prefer something that automatically starts and logs data for later analysis than something like Process Explorer, which always leaves me worrying that by the time it started the problem had gone away :-)  I guess my ideal would be 2 things:   Something that gave me an overall "what are the current key bottlenecks in this system" summary (ideally, which could be set to run in the background and collect data for later analysis). Some means of starting a program (say, Firefox) and have it record what was going on in terms of waits and delays in the system.   Unfortunately, I've never really found anything like either of these.  I'm not a professional systems admin - my background is database admin - so if there are "obvious" tools to look at or try, then I'd be grateful to know of them (particularly if the information they give is easy for an amateur to analyze) :-)


For example, if I wanted to say, "This student is large.", would it be proper to instead say, "This student's large."? I don't recall ever reading something like this, but I remember hearing people speak like this. Is this purely a speaking shortcut or is it also proper to write as well?

How compelled should I feel to use non-contracted forms (do not rather than don't and so on) when writing in a rather formal text, say an academic paper? In one case I am afraid to seem too stilted, in the other, too casual. Are there good guidelines?  And are there differences in this regard between British and American English?  (In this  there was not much more than "Contractions are more frequent in informal than formal contexts".)


I want to extrude these edges outward so that they are all the same length from their origin edge. Does anyone know how I could do this without doing each edge individually?

Is there an operation similar to inset that creates faces in the opposite direction? That is, instead of creating faces inwards, they create faces outwards? A normal inset operation:  What I would like:


When I run sudo apt-get update on Ubuntu Server 14.04, it seems to be making a lot of requests to http:// sources. I would expect that something as important (and dangerous!) as updates would be handled over an encrypted connection (https://) but it appears it isn't. Why is that?

Does apt-get use https or any kind of encryption? Is there a way to configure it to use it?


I know how to do the commands already, but I can't seem to be able to get to do it all in one command, because I can't target an already made item so I can enchant, but not name/ give it lore.

I have heard it was possible to change the names and lores of Minecraft items WITHOUT the use of third-party programs like MCEdit. Given the things that my friends have told me, and from the information gathered online, my guess is that, since Minecraft has started using JavaScript, /give @p 35 1 14 {name:"Red Wool",lore:"bob"}. Whenever I run this command block, all I get is a piece of Red Wool with no Lore, nor a name. I also get no errors in this process.


I'm trying to find a book I remember reading a long time ago.  In it the main character could teleport or "cast" objects.  A few of the details I remember (here's hoping I don't have multiple books mixed in my mind):  Teleporters could cast 1000 kg and not a bit more.  They had to go to a school to learn to compensate for momentum differences between the start and the target location.  The main character ran into someone who called themselves an 'anchor' who could block the teleportation.  They got past the anchor by teleporting drugs meant for him directly into the anchor.  I think there was a part at the beginning about someone who seemed to be in withdrawal finding him as a baby by following a ringing noise and saying he had 'rung a gold' or something like that.  The guy seemed to recover once he hung around the boy and trained him.  That last part could be a different book however...

I could swear that I got this answered once via the TVTropes YKTS forum, but all I can find is my failed query.   It's a Sci-fi novel, involves the last member of an alien race saying that a particular child will be a savior of the galaxy. Everyone assumes that this means that he will be able to transcend the teleportation limits (if I recall correctly, they could teleport up to some amount, say 22 kilograms, but the moment they added a gram more, it failed). His father was a former football player and it was referenced a few times that he used a football carry for the baby with the head in one hand and the rest of the body on one forearm. The parents were killed by some sort of extremists and the boy was tested for his teleportation abilities and they found that he couldn't transcend the limit. And... that's about all I remember.  I read it in middle school, I believe, so that means it was definitely published before 2000 and likely before 1994.


The shellscript is very simple:  retroarch $* -c /tmp/retroarch/Data/retroarch/gambatte.cfg   ("retroarch" is another shellscript)  If the filename passed contains spaces it fails:  RetroArch [ERROR] :: Could not read ROM file.

I wrote the following script to diff the outputs of two directores with all the same files in them as such:  #!/bin/bash  for file in `find . -name "*.csv"`   do      echo "file = $file";      diff $file /some/other/path/$file;      read char; done   I know there are other ways to achieve this.  Curiously though, this script fails when the files have spaces in them.  How can I deal with this?  Example output of find:  ./zQuery - abc - Do Not Prompt for Date.csv


I am currently using a wizard. I was wondering, if I decided to take a feat that would allow me to use heavier than light armor, would that affect my spellcasting?  I thought I read something about it in the rule book but I can't find it.

I've just read the , and I'm not sure I'm up to speed regarding casting spells while clad in armor. The only mention I can find about this (page 79):     Because of the mental focus and precise gestures required for   spellcasting, you must be proficient with the armor you are wearing to   cast a spell. You are otherwise too distracted and physically hampered   by your armor for spellcasting.   Does this mean that a character who starts out with a single level fighter (or any other class with heavy armor proficiency) can from then on gain levels as wizard and forever more cast spells, without any penalty whatsoever, while wearing full plate?  I've played all editions of D&D, and this seems both a bit overpowered and very un-D&D-ish to me. Have I missed something?


I am creating a dynamically generated html
 in jquery which has some
 elements in it. I want an active class be added to any of the
 elements by hovering. I've tried some functions in jquery but it won't change
 elements, it will only work if I try it on
 element. Here is my html code:

    My Javascript code:   $.ajax({         url: myURL,         method: "GET",         headers: { "Accept": "application/json; odata=verbose" },         success: function (data) {             if (data.d.results.length > 0) {                 AllTask = data.d.results;                 html = '';                              for (var i = 0; i < Number(AllTask.length); i++) {                     html += '
';                     html += '

';                     html += '';                     html += '
' + AllTask[i].Title + '
';                     html += '
' + AllTask[i].meeting_place + '' + JDate + '

';                                      }  document.getElementsByClassName('meeting_lists')[0].innerHTML = html;    and my jquery function:   $(".all_session_section  ul > li").hover(   function () {     $(this).addClass("active");   },   function () {     $(this).removeClass("active");   } );    if anyone can help me with this, I would really appreciate that.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


So unbelievably I have never cleared my history in SMS/iMessages/Messages. Ostensibly, I should be able to scroll up and eventually see my first text message from my first gen iPhone. This is, unsurprisingly, taking up a considerable amount of space on my phone, but a big part of why I've never cleaned it out is that it contains a tremendous number of pictures of my daughters my wife has sent me over the years. It doesn't seem like these get saved to my photo roll and there doesn't appear to be any way to bulk export them. It may be worth noting that I use desktop messages in Yosemite and it seems work well, so there may be an approach I can use from that angle.  What's the best way for me to archive all the photo attachments from almost seven years of text messages?

I am getting a new iPhone come next month. I want to save all of my nostalgic conversations for the future.  Is there a way to transfer an entire chat log to the computer in plain text?  Or will I have to painstakingly take screenshot after screenshot as I scroll up in the text history?


I just found out that the following code is not a valid C++ (it doesn't parse at int after ~):    int x = 5; x.~int();   However, the following snippet does work:  int32_t x = 5; x.~int32_t();   This is because int32_t is a typedef in my particular implementation of C++, and a destructor can, apparently, be called on any typedef'ed type.  My question is: is any implementation of C++ required to allow the second snipped to compile? In particular, is int32_t guaranteed to be a typedef, and is the compiler required to allow a destruction of a typedef if it knows that typedef typedefs something to int?

In C++ the following code gives a compiler error:  void destruct1 (int * item) {   item->~int(); }   This code is nearly the same, I just typedef the int to another type and something magic happens:  typedef int myint;  void destruct2 (myint * item) {   item->~myint(); }   Why does the second code work? Does an int get a destructor just because it has been typedefed?  In case you wonder why one ever would like to do this: This comes from refactoring C++ code. We're removing the standard heap and replacing it with selfmade pools. This requires us to call placement-new and the destructors. I know that calling destructors for primitive types is useless, but we want them in the code nevertheless in case we later replace PODs with real classes.  Finding out that naked int's don't work but typedefed ones do was quite a surprise.  Btw - I have a solution that involves template-functions. We just typedef inside the template and everything is fine.


I'm currently working on a Regression Model involving multiple categorical variables. While researching on how to proceed on this I came across "Dummy Coding", which I'm totally fine with and later I stumbled upon "Effect Coding", which is bothering me with.   I want to know, how do these two ways of coding differ and also what changes would it make to my model, if I code my Categorical variables with both these models separately.  Would be highly helpful if someone could explain with some R code samples.

If you fit a linear model or a mixed model there are different types of codings available to transform a categorical or nominal varibale into a number of variables for which paramaters are estimated, such as dummy conding (the R default) and effects coding.  I heard that effects coding (sometimes called deviation or contrast coding) is preferred when you have interactions, but what are the possible contrasts and when would you use which type of contrast?  The context is mixed modeling in R using lme4, but I think broader responses are fine. Sorry, if I missed a similar question.  EDIT: Two helpful links are:  &  explained.


I have come across some shots from other people and they create something like an illusion to me and trick me of the scale of the actual scenery.  For example, this shot by  on Unsplash made me think that this it is miniature; some sort of Meccano, plastic model or a 3D recreation. It looks too perfect and clean!   Proof that it is actually real can be seen when you zoom-in and notice there's a person near the front of the bus, some too fine detail on the roof of the bus stop and some other details.  I have tried to capture pictures in a similar style using a DJI Mavic Pro Platinum drone, tried editing with Photoshop, but I can't give my shots that feeling.  What do you think the camera configuration and settings are? Is this effect entirely made with graphic manipulation? Any hint or advice will be highly appreciated!

I was browsing Behance and came upon these pictures:   I was wondering how he got this miniature style effect? I'm guessing a Gaussian Blur on a strip of the picture in Photoshop...but couldn't get right. What's the step-by-step process for doing this with software?  (For getting this effect with a special lens, see )


I have two files with the same number of words and column fields in each line. I want to append these two files word by word. For example:  File 1:  A1 B1 C1 D1 E1 B1 C1   File 2:  A2 B2 C2 D2 E2 B2 C2   The output should be (the number of words should be respected):  A1_A2 B1_B2 C1_C2  D1_D2 E1_E2 B1_B2 C1_C2

I have 2 large files (3000 columns, 15000 rows) of the following format  file1 (tab-separated):  1/0 0/0 0/0 0/0 1/1 0/0 1/1 0/1 0/0   file2 (tab-separated):  3 5 2 1 7 10 3 4 3   I'd like to combine the values from the first column of each file with a ":" separator, then move on to the second, third, etc. columns.  Desired output (tab-separated):  1/0:3 0/0:5 0/0:2 0/0:1 1/1:7 0/0:10 1/1:3 0/1:4 0/0:3   Efficiency isn't critical, so any language is fine. I apologize if this has been asked before.


Let let $$f(x,y)=\frac{x^3-y^3}{x^2+y^2}$$ and $(x,y)\not=(0,0)$   How to prove that the function has a limit as $(x,y)\to (0,0)$     Should I look at firstly on the x axis and then on y-axis?

In class, we were simply given that this limit is undefined since along the paths $y=\pm x$, the function is undefined.  Am I right to think that this should be the case for any function, where the denominator is $x^2-y^2$, regardless of what the numerator is?  Just wanted to see if this is a quick way to identify limits of this form.  Thanks for the discussion and help!


I have a publish subscribe queue message listener method which fires an event when it reads a message in the queue & adds the message to a publisherPostListenerList  in the ApplicationListener class.   The messages added in the list are being pushed to multiple subscribers like real time notifications from the controller method.   After pushing the message to a respective logged in user I am removing the message from the list to avoid the push of redundant message to the user also it keeps in check the size of the list.   The problem is there is only single instance of publisherPostListenerList for all the logged in users. The list being an instance list there should be a separate copy for every logged in user but its not the case. Please correct me if I am wrong.  If I delete a message it deletes the message from the publisherPostListenerList  for all the subscribers.   Now my questions are   1. Shouldn't there be an individual copy of publisherPostListenerList list for every logged in user, the list being an instance list.  2. How do I create a separate copy of list for all the logged In users  P.S. I tried changing the bean scope to prototype but didn't work.   Below is the ApplicationEventListener class which holds the list & the controller code.   ApplicationListener.java  @Component public class ApplicationEventListener {      private List<Post> publisherPostListenerList = new CopyOnWriteArrayList<Post>();      private static final Logger logger = Logger.getLogger(ApplicationEventListener.class);      @EventListener     public void postSubmissionEventHandler(PostSubmissionEvent event) throws IOException {         Post post = event.getPost();         logger.debug("application published user post received " + post);         publisherPostListenerList.add(post);     }      public List<Post> getPublisherPostListenerList() {         return publisherPostListenerList;     }      public void setPublisherPostListenerList(List<Post> publisherPostListenerList) {         this.publisherPostListenerList = publisherPostListenerList;     } }   Controller method for pushing the message to the subscriber  @RequestMapping(value="/getRealTimeServerPushUserPosts")     public SseEmitter getRealTimeServerPushUserPosts(@RequestParam("userId") int userId){         SseEmitter sseEmitter = new SseEmitter();         CustomUserDetail myUserDetails = currentUserAccessor.getCurrentLoggedInUser();         User loggedInUser=myUserDetails.getUser();          List<Integer> userPublisherIDList = this.userService.loadUserPublisherIdListWhichLoggedInUserFollows(loggedInUser);         List<Post> postList =eventListener.getPublisherPostListenerList();           for(Integer userPublisherId : userPublisherIDList){             for(Post post:postList){                     if((userPublisherId.intValue()) == (post.getUser().getUserId().intValue())){                         try {                         sseEmitter.send(post);                         postList.remove(post); //removes the post for all the subscribers as the list acts as a global list.                     } catch (IOException e) {                         logger.error(e);                     }                 }              }          }         return sseEmitter;     }

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


I'm using this command: gnome-open file_name.xxx(xxx file extension) command but it's not working. I'm using Ubuntu 14.04.

I used to work on the Mac terminal before and I used:   open file2open.pdf   and the PDF file would be opened on preview or whatever my default viewer was. When I use it in the terminal in Ubuntu I get this error message:   Couldn't get a file descriptor referring to the console


Is it posible to compile Java source (which uses libraries like Swing etc) in an exe file, so the user doesn't need to install JavaSE?  I am looking for some way to bundle a mini-JRE and the .jar in a single file (exe) or some way to compile everything (source and libraries) into native code.  PS: Obviously I don't care about cross-compat for that program.

If I have a Java source file (*.java) or a class file (*.class), how can I convert it to a .exe file?  I also need an installer for my program.


I need help in the following proposition:  Let $f_n$ be a sequence of lebesgue measurable functions $f_n : [a,b] \rightarrow \mathbb{\overline{R}}$ then lim sup $f_n$, lim inf $f_n$ $[a,b] \rightarrow \mathbb{\overline{R}}$ are both lebesgue measurable functions.  I don't know how to manipulate those functions to proove $ \{x\in[a,b]: f^*(x)> \alpha \} $ where $f^* $ is limit superior and $f_*$ is limit inferior

I need help to prove the following theorem      Suppose $f$ is the pointwise limit of a sequence of $f_n$, $n = 1, 2, \cdots$, where $f_n$ is a Borel measurable function on $X$. Then $f$ is Borel measurable on $X$.   My idea is to use the standard definition like for every $c$,$\{x:f(x)<c\}$ is Borel measurable. But got stuck as how to do it for sequence of $f_n$.


I want to align a text in a  or  element to this custom switch button:    .switch {   position: relative;   display: inline-block;   width: 60px;   height: 34px; }  .switch input {   opacity: 0;   width: 0;   height: 0; }  .slider {   position: absolute;   cursor: pointer;   top: 0;   left: 0;   right: 0;   bottom: 0;   background-color: #ccc;   -webkit-transition: .4s;   transition: .4s; }  .slider:before {   position: absolute;   content: "";   height: 26px;   width: 26px;   left: 4px;   bottom: 4px;   background-color: white;   -webkit-transition: .4s;   transition: .4s; }  input:checked+.slider {   background-color: #2196F3; }  input:focus+.slider {   box-shadow: 0 0 1px #2196F3; }  input:checked+.slider:before {   -webkit-transform: translateX(26px);   -ms-transform: translateX(26px);   transform: translateX(26px); } /* Rounded sliders */ .slider.round {   border-radius: 34px; } .slider.round:before {   border-radius: 50%; } Custom switch    <input type="checkbox" checked>         I cannot get it working setting the margin or float on the switch class element.

I have a div with two images and an h1. All of them need to be vertically aligned within the div, next to each other. One of the images needs to be absolute positioned within the div. What is the CSS needed for this to work on all common browsers?

testing...


I want to know, what is the largest prime number? I know prime numbers are whole numbers that cannot be divided by any whole number except 1 and themselves, I also know some primes  like 2, 3, 5, 7, 11... But what is the largest prime number?

This is just a curiosity. I have come across multiple proofs of the fact that there are infinitely many primes, some of them were quite trivial, but some others were really, really fancy. I'll show you what proofs I have and I'd like to know more because I think it's cool to see that something can be proved in so many different ways.  Proof 1 : Euclid's. If there are finitely many primes then $p_1 p_2 ... p_n + 1$ is coprime to all of these guys. This is the basic idea in most proofs : generate a number coprime to all previous primes.  Proof 2 : Consider the sequence $a_n = 2^{2^n} + 1$. We have that  $$ 2^{2^n}-1 = (2^{2^1} - 1) \prod_{m=1}^{n-1} (2^{2^m}+1), $$  so that for $m < n$, $(2^{2^m} + 1, 2^{2^n} + 1) \, | \, (2^{2^n}-1, 2^{2^n} +1) = 1$. Since we have an infinite sequence of numbers coprime in pairs, at least one prime number must divide each one of them and they are all distinct primes, thus giving an infinity of them.  Proof 3 : (Note : I particularly like this one.) Define a topology on $\mathbb Z$ in the following way : a set $\mathscr N$ of integers is said to be open if for every $n \in \mathscr N$ there is an arithmetic progression $\mathscr A$ such that $n \in \mathscr A \subseteq \mathscr N$. This can easily be proven to define a topology on $\mathbb Z$. Note that under this topology arithmetic progressions are open and closed. Supposing there are finitely many primes, notice that this means that the set $$ \mathscr U \,\,\,\, \overset{def}{=} \,\,\, \bigcup_{p} \,\, p \mathbb Z $$ should be open and closed, but by the fundamental theorem of arithmetic, its complement in $\mathbb Z$ is the set $\{ -1, 1 \}$, which is not open, thus giving a contradiction.   Proof 4 : Let $a,b$ be coprime integers and $c > 0$. There exists $x$ such that $(a+bx, c) = 1$. To see this, choose $x$ such that $a+bx \not\equiv 0 \, \mathrm{mod}$ $p_i$ for all primes $p_i$ dividing $c$. If $a \equiv 0 \, \mathrm{mod}$ $p_i$, since $a$ and $b$ are coprime, $b$ has an inverse mod $p_i$, call it $\overline{b}$. Choosing $x \equiv \overline{b} \, \mathrm{mod}$ $p_i$, you are done. If $a \not\equiv 0 \, \mathrm{mod}$ $p_i$, then choosing $x \equiv 0 \, \mathrm{mod}$ $p_i$ works fine. Find $x$ using the Chinese Remainder Theorem.   Now assuming there are finitely many primes, let $c$ be the product of all of them. Our construction generates an integer coprime to $c$, giving a contradiction to the fundamental theorem of arithmetic.  Proof 5 : Dirichlet's theorem on arithmetic progressions (just so that you not bring it up as an example...)  Do you have any other nice proofs?


How to make so that page will have no number in latex? I mean for example if i dont want first page to have number "1" under

I am a newbie in Latex. I know there are many manuals where I can learn how to use Latex but I am facing a problem I can't manage to solve simply. The structure of my document is this:   title page abstract table of contents   The problem is that I don't want that the abstract page to have the page number at the bottom. To do this in the title page I simply used the command \pagestyle{empty} . Now if I try to do the same with the abstract page it doesn't work. Here it is the code of my document:  \begin{document}  \pagestyle{empty}  \begin{figure}[t] \centering \includegraphics[scale=.40]{Sapienza.png} \vspace{3em} \end{figure}  \begin{center} %%%% here there are many sentences \end{center}  \clearpage{\pagestyle{empty}\cleardoublepage}  \pagestyle{empty} %%in order to delete the number at the bottom of the page  \chapter*{Abstract} %%sentences  \pagestyle{plain}%%to insert again the number of the page  \tableofcontents   The problem is that the abstract page keeps showing the page number and I can't manage to delete it. Can you please help me?


I recently purchased a new, Silicon Power high-quality micro-SD card. I used it multiple times as a boot disk for my Raspberry Pi, each time I burned a 4gb disk image and installed the OS, then connected it to my computer and reformatted the SD card to a 64gb FAT32 filesystem with Windows' diskpart program. However, yesterday, after successfully burning the disk image, which was able to successfully boot the computer, I am unable to resize and reformat the disk. I tried using Diskpart, but i get data error (Cyclic Redundancy Check), and since a number of sites recommended chkdsk, I am unable to use chkdsk because I have a raw filesystem.  This seems like a dead end, because people recommend chkdsk to fix a cyclic redundancy check, but I cannot use chkdsk because I am stuck with a RAW filesystem, which I am unable to format because of Cyclic Redundancy Check errors. There is absolutely no important data on my drive, and I do not have any problem reformatting and clearing all the data on the drive, so I am not looking for a data recovery solution, I am looking for a solution that will allow me to use my 64gb drive again.  I am stuck, please help me recover my drive. Thank you very much!  EDIT: I broke my Raspberry Pi, so I can no longer do any solutions that require the Raspberry Pi. However, I still have a Windows laptop running Windows 8.1.

I received a new HDD from my uncle, RAW file system. Tried CHKDSK, but it didn't work because of the RAW file system.      Update  I ran SpinRite 6 overnight and it got nowhere. Stayed at 0% for the whole 10 hours. SpinRite also gave me a notification that this drive is most probably toast. I think I am going to throw this drive away.


I am new to QGIS.   I have multiple DEM raster files (.tif) added to my map. However, I am unable to alter any of the style options under the "Band Rendering" section.  I have attempted to make changes and then save it as a new style, just clicking okay, just clicking apply, etc. Yet, every time, the original style choices are still there when I reopen the raster's properties. I am able to make changes to all other style options.  I'm particularly interesting in changing the color gradient from "Black to white" to "White to black".

In a raster layer's Style Properties, I can choose pseudocolor render type, and choose a color ramp and classify the raster.      However, when I click the 'Apply' button, or click 'OK', the visualization of the raster never changes.  I was able to output a 'colorized' version of the same raster using GRASS plugin.  I also reinstalled QGIS 2.8, and was able to adjust and see a raster stylings using the steps I outlined above.  So, can anyone confirm this as an issue, or confirm that there's a mistake somewhere in my process?  I should note that I'm on a Mac, 10.10.4, and I'm using the QGIS provided by , 2.10.1-1 .  Update 1: Here's a screenshot of the rest of my settings.      I have Grayscale set to off in the Style setting.  Also, I don't believe grayscale/color-blind Preview is available on the Mac version of QGIS.  They're does't appear to be the option where it , in the Menu Bar under View / Preview / Photocopy (grayscale) etc.  Either way-- I added a shapefile to show color.  Update 2: I've experimented with setting color interpolation to discrete, linear, and exact, but still am not able stylize using Singleband pseudocolor.  I've also confirmed that the 'Render' box on the the main map view is checked.  Also, I am able to adjust Color Rendering settings, like Hue, Blending Mode, etc., and see the results when clicking 'Apply' or 'OK'.  Update 3: As other Mac users are confirming this, I think it may be a bug. I've created a bug report at the official .


Let $f:[0,\infty)\to\mathbb{R}$ be bounded on every interval $[0,b]$ for $b\gt0$. Assume that $$\lim_{x\rightarrow\infty}\left(f(x+1)-f(x)\right)=0.$$ How do I prove that $$\lim_{x\rightarrow\infty} \frac{f(x)}{x}=0?$$

Let $f:[0,+\infty)\to\Bbb R$ be a function bounded on each finite interval. I want to show that if $\lim\limits_{x\to+\infty}[f(x+1)-f(x)]= L,$ then also $\lim\limits_{x\to+\infty}\dfrac{f(x)}x = L$


Why does Quantum Field Theory use usually Lagrangians rather than Hamiltonains?  I heard many reasons, but I'm not sure which is true.   Some say it's just a matter of beauty, so Lagrangians are more beautiful because they don't break/separate the space-time variables (so space-time is a single variable, like in the Klein-Gordon Lagrangian and Hamiltonian).  Some say that Hamiltonians are not always Lorentz invariant.  Could someone explain in a little bit more details?

Undergraduate classical mechanics introduces both Lagrangians and Hamiltonians, while undergrad quantum mechanics seems to only use the Hamiltonian. But particle physics, and more generally quantum field theory seem to only use the Lagrangian, e.g. you hear about the Klein-Gordon Lagrangian, Dirac Lagrangian, Standard Model Lagrangian and so on. Why is there a mismatch here? Why does it seem like only Hamiltonians are used in undergraduate quantum mechanics, but only Lagrangians are used in quantum field theory?


i hava a php code inside a javasript for loop  code the problem is the php code run once even though the loop go many times  here is my code  <script>    function myFunction() {     var j,i,k,x=[];       <?php $k=0; ?>;   <?php $faculys= App\faculty::all();     $i=0;      foreach($faculys as $faculty)     {       $array[]=$faculty->name;       $i++;     }       ?>;       i= <?php echo $i; ?>; for(j=0; j<i; j++)       {          x[j]='<?php  echo $array[$k];  ?>';        <?php $k++; ?>;        }    k= <?php echo $k; ?>; </script>   the result of $k and k is always one what is my error.

I want to use a PHP variable in JavaScript. How is it possible?


I am new to lubuntu. I have installed java8 in my laptop. i need to set up environment variable (sudo nano /etc/environmet) i have entered the JAVA_HOME =" path" but i dont know how to properly save and exit the window. Can you please help me with this ?

Sometimes, a graphical text editor like gedit or kate cannot be used (because you're in a virtual console for example). Luckily, there are text editors for the terminal. An easy one is nano, but I cannot understand how to work with it.  If I start nano by running nano, the bottom text is supposed to help me but all I see are things like ^G Get Help    ^O WriteOut.   How can I open text files for editing? How can I save the file? How can I quit the editor without saving the changes? How to edit? I heard that you've to enter some commands to begin editing in vi, is this true for nano too? Sometimes, if I manage to open a file, the text is unreadable due to its colors. How can I disable these colors? (see the image below) In the some files, lines are truncated because those do not fit in the screen. How can I prevent that from happening? (see the image below)


I am new to JAVA and just started learning IS-A and HAS-A relation but couldn't get much .I want to visualize how these two are different and when we should be using IS-A and HAS-A ?

Why prefer composition over inheritance?  What trade-offs are there for each approach?  When should you choose inheritance over composition?


Let $S=[0,1)\cup [2,3]$ and let $f:S\to \mathbb{R}$ be strictly increasing such that $f(S)$ is an connected subset of $\mathbb R$. How to show that $f$ is continuous?  $f(S)$ is connected means it is an interval. Also $f$ is one-one. But I couldn't proceed further. Please suggest!

Let $S = [0,1) \cup [2,3]$ and $f\colon S \rightarrow \mathbb R$ be such that $f(S)$ is connected . Which of the following are true:  a) $f$ is discontinuous exactly at one point.  b) $f$ is discontinuous exactly at two points.  c) $f$ is discontinuous at infinite many points.  d) $f$ is continous.  I think $f$ is continuous . We need to show that $\lim_{x \to a^+}f(x) = f(a)$ for any $a \in S$. Since $f(x)$ is increasing, $\lim_{x \to a^+}f(x) \leq f(a)$. Suppose $\lim_{x \to a^+}f(x) < f(a)$. Then there is $l$ such that $\lim_{x \to a^+}f(x) < l <f(a)$, which contradicts connectedness of $f(S)$. Similarly we can show that $\lim_{x \to a^-}f(x) = f(a)$.  I would be thankful if anyone would check my solution and correct me if there are any errors.


Imagine two objects of mass $m$ each (both of them in outer space), with initial velocities $v_0$ and $0$. Now I apply a constant force $F$ on both of them for time $t$. Now the change in energies of the masses are $$\Delta E_1=m v_0\Delta v + \frac{1}{2}m\Delta v^2$$ $$\Delta E_2=\frac{1}{2}m\Delta v^2$$ What these equations are saying is that I lose more energy when I try to accelerate an already moving object (same amount of momentum transfer doesn't mean same amount of energy transfer). This doesn't make sense. If I look at it mathematically, i.e $dW = \vec{F} \cdot \vec{ds}$, I completely understand why I'll have to spend more energy on the moving object. But for some reason my intuition says if I apply same force on objects moving at different velocity for the same amount of time, I'll lose the same amount of calories. Where is my intuition wrong?

Consider a rocket in deep space with no external forces. Using the formula for linear kinetic energy $$\text{KE} = mv^2/2$$ we find that adding $100\ \text{m/s}$ while initially travelling at $1000\ \text{m/s}$ will add a great deal more energy to the ship than adding $100 \ \text{m/s}$ while initially at rest: $$(1100^2 - 1000^2) \frac{m}{2} \gg (100^2) \frac{m}{2}.$$ In both cases, the $\Delta v$ is the same, and is dependent on the mass of fuel used, hence the same mass and number of molecules is used in the combustion process to obtain this $\Delta v$. So I'd wager the same quantity of chemical energy is converted to kinetic energy, yet I'm left with this seemingly unexplained $200,000\ \text{J/kg}$ more energy, and I'm clueless as to where it could have come from.


Blender 2.79 Two objects with identical material settings and no texture. Viewed in Object Mode/Solid View the one on the left has a dark, bluish tint. The two look identical in other views and render with identical colors. But why the different colors in Solid View?  A minor but nagging and annoying nuisance. Much thanks from a newbie.

While rendering a mesh with smooth shading on, I get a dark region/shadow on certain faces. The effect is more evident when smooth shading is applied to a mesh containing ngons, with the ngons turning black when rendered.   The blackening effect is visible in the viewport too.  How can I solve this problem?


I can't get the AWS CLI using python2.7 to work after upgrading to Ubuntu 16.04LTS.  I've tried the suggestions from  with no luck.  I also uninstalled and reinstalled python2.7.  The error I get is ImportError: No module named datetime

OS: Ubuntu 14.04 LTS  Python: 2.7.6  My installation of Gourmet Recipe Manager suddenly stopped loading. When I run it in a terminal window, I get the following at the end of the traceback:  import datetime as dt ImportError: No module named datetime   So far as I can tell, nothing has been changed and my Python installation is up to date. It simply quit working yesterday. I'd certainly appreciate a good approach to diagnose and fix this problem!  Update: thanks to all who replied!  Tim, I'm sorry if I asked this question in the wrong place. Please chalk it up to being a new guy simply following the links from the Ubuntu website.  TheSchwa, I tried your suggestion and got the same error message as above.  muru, the package seems to be installed, but I have no idea if it's installed/configured correctly. How might I find out?  I'm sorry for all the questions, but I'm an old RedHat guy who has been away from Linux for some time. All of the apt/dpkg stuff is new to me.


$mx''+25x = 12 cos(36πt)$ my take on this: ${\omega_0} = \sqrt{k \over m} = \sqrt{25 \over m}$ $x_h = c_1cos({\omega_0}t) + c_2sin({\omega_0}t)$ $x_h = c_1cos(\sqrt{25 \over m} t) + c_2sin(\sqrt{25 \over m}t)$ $x_p = {{12 \over {m({\omega_0^2 - \omega^2})}}cos(36\pi t)} = {{12 \over {25-1296m^2}}cos(36\pi t)}$ but I am stuck here. am I on the wrong road?

Problem:  $$y''+20y=100\sin(wt)$$  conditions:  $$y(0)=2, y'(0)=0$$  What would the solution for $y(t)$ be when $w=2\sqrt 5$  So far I have GS(H)=Acos($\sqrt 20$)+Bsin($\sqrt 20$).


I know the original movies, as well as I think the Clone Wars and Rebels cartoons were brought forward. I know Disney's movies are canon, and I assume the books being released after Disney purchase are canon as well.  But are all things put out after Disney purchase canon? Like story mode of Battlefront 2?  Curious what gets labeled as canon and what does not, and is there a distinction to know the difference?

For all types of derivative works, namely:   Movies Novels Comic books Other written works (including RPG materials) Cartoons Video games Derivative movies (such as the infamous Ewok movies and even more infamous )   According to what rules does something become "canon" and who is responsible for the evaluation of a published work?


UPDATE:  It's a padding: every such non-rwx area is preceded with a readable and/or writable area and together they constitute a 64Mb segment (for 64bit architecture).  A relevant question on SO:   I have discovered there are plenty of VM segments that don't have any of rwx flags, just p:  7f7e98033000-7f7e9c000000 ---p 00000000 00:00 0 Size:              65332 kB Rss:                   0 kB Pss:                   0 kB Shared_Clean:          0 kB Shared_Dirty:          0 kB Private_Clean:         0 kB Private_Dirty:         0 kB Referenced:            0 kB Anonymous:             0 kB AnonHugePages:         0 kB Swap:                  0 kB KernelPageSize:        4 kB MMUPageSize:           4 kB   Any reference on what it means?  Unlike what's described in , it's not a mapping from a shared library since it does not have a corresponding fd attached. It's a custom long running C++ daemon, but I found some other processes have similar usage patterns: eg erlang (which also has plenty of them). In contrast long running php-fpm and python processes have literally 0 of such segments. "What other mappings does it have?" --- everything else is kind of expected and usual: just normal r/w private segments and shared libraries.

Why does /proc/pid/maps contain a few records for the same library ? Here is an example:  7fae7db9f000-7fae7dc8f000 r-xp 00000000 08:05 536861                     /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20 7fae7dc8f000-7fae7de8f000 ---p 000f0000 08:05 536861                     /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20 7fae7de8f000-7fae7de97000 r--p 000f0000 08:05 536861                     /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20 7fae7de97000-7fae7de99000 rw-p 000f8000 08:05 536861                     /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20   What does this mean ?


Is there a way to make underscored/underlined text?  I read editing help and there seem to be nothing about that. By underscored I mean what in HTML is done with ...:  Alice wanted to emphasize that her dress is fabulous.   "Layman's logic" would suggest using actual underscore _ to create such feat but it make things italicized.  So question remains - is there a way to underscore a text?

Why is it that italic and bold formatting is available while underline is not?  I guess it is voluntary, I'm just wondering why that would be the case.