Here's an example:  Double d = (1/3); System.out.println(d);   This returns 0, not 0.33333... as it should.  Does anyone know?


I have a exploit virus detected by ClamTK that I Can't remove

I cannot delete or quarantine.    /usr/share/mime/mime.cache PUA.Win.Exploit.CVE_2012_01


How do I calculate the required value for a pull-up resistor?

There are many tutorials that use a pull-up or pull-down resistor in conjunction with a switch to avoid a floating ground, e.g.        Many of these projects use a 10K resistor, merely remarking that it is a good value.  Given a a particular circuit, how do I determine the appropriate value for a pull-down resistor?  Can it be calculated, or is it best determined by experimentation?


Upgrade to 20.04 from 19.10 isn't available

I upgraded from 18.04 to 19.10 some months ago and now I want to upgrade to 20.04. But update-manager -c doesn't show the new Ubuntu release 20.04.  Isn't the upgrade ready yet? Is it possible to upgrade to 20.04 from 19.10 now?


Blender 2.8 can no longer import module from Textblock

just downloaded todays Blender 2.8 build and it seems I can no longer import a function from another Textblock. Works well on a build from April 5th (haven't updated since then).  This simple example is not working in todays build:


Is there any way to make/run a bash script on reboot (like in Debian/Ubuntu for instance, since thats what my 2 boxes at home have)  Also, any recommended guides for doing cron jobs? I'm completely new to them (but they will be of great use)


Redirecting output of `man ` to file produces file with tons of `^H` characters on OS X

The following behavior occurs in OS X (10.9.5) with the BSD utils, but not Linux (Ubuntu 15.10) with the GNU utils.  OS X:   $ man -v  man, version 1.6c   Linux:   $ man --version  man 2.7.4   I'm trying to write a shell script to automatically parse the supported options for a given program for use in bash/tcsh autocompletion. For instance here's the name and synopsis section output by name perl when viewed in the terminal.  $ man perl | cat  NAME        perl - The Perl 5 language interpreter  SYNOPSIS        perl [ -sTtuUWX ]      [ -hv ] [ -V[:configvar] ]             [ -cw ] [ -d[t][:debugger] ] [ -D[number/list] ]             [ -pna ] [ -Fpattern ] [ -l[octal] ] [ -0[octal/hexadecimal] ]             [ -Idir ] [ -m[-]module ] [ -M[-]'module...' ] [ -f ]             [ -C [number/list] ]      [ -S ]      [ -x[dir] ]             [ -i[extension] ]             [ [-e|-E] 'command' ] [ -- ] [ programfile ] [ argument ]...  $ man perl > /tmp/perl.out   I first got suspicious when  $ </tmp/perl.out awk '/SYNOPSIS/ {print}'   didn't print any lines, then I opened the file in vi and saw this. Why the heck are there so many unnecessary duplicated characters and ^H characters.  N^HNA^HAM^HME^HE        perl - The Perl 5 language interpreter  S^HSY^HYN^HNO^HOP^HPS^HSI^HIS^HS        p^Hpe^Her^Hrl^Hl [ -^H-s^HsT^HTt^Htu^HuU^HUW^HWX^HX ]      [ -^H-h^Hhv^Hv ] [ -^H-V^HV[:_^Hc_^Ho_^Hn_^Hf_^Hi_^Hg_^Hv_^Ha_^Hr] ]             [ -^H-c^Hcw^Hw ] [ -^H-d^Hd[t^Ht][:_^Hd_^He_^Hb_^Hu_^Hg_^Hg_^He_^Hr] ] [ -^H-D^HD[_^Hn_^Hu_^Hm_^Hb_^He_^Hr_^H/_^Hl_^Hi_^Hs_^Ht] ]


When connecting to a server, is there a way to keep the SSH console open once disconnected? Or is there a program that does that, and that lets me connect back into where I left?  This situation can happen for instance if I start a simple manual backup using cp from towards that takes +1h. I may not be able to wait and have to close the connection, but I still want my command to finish and I may even login later and check the result message.  My current method achieving this, is to login to the a desktop installed on server using VNC. Open terminals remain open and I can let them run something, log off, and come back later and just continue where I where I stopped.  Is that possible within the command line so that I am not dependent on the remote desktop?


How can I connect to the same server in Agar.io?

Choose any server  Right click - Inspect element (or press f12) Click console  From console copy the websocket ip -> 'ws://x.x.x.x/x' write connect("ws://x.x.x.x/x") example: connect('ws://123.122.199.84:43')   These steps will allow to connect to a specific server. This way you can play with your friends in the same server.  My question is is there a way to open a web socket via url bar? For example is there a way to write something like  for directly connecting to a server?


How to obtain and use the .bbl file in my tex document for ArXiv submission?

I am submitting my first article to ArXiv and in the instructions they specify I have to include the .bbl file. Their instructions are:  "We do not run BibTeX in the auto-TeXing procedure. If you use it, include in your submission the .bbl file that BibTeX produces on your own machine; otherwise your references will not come out correctly. We do not run BibTeX because the .bib database files can be quite large, and the only thing necessary to resolve the references for a given paper is the .bbl file. The name of the .bbl file must match the name of the main .tex file for the system to process the references correctly."  My knowledge of LaTeX is basic, and I have not heard of .bbl file before. I am using TeXmaker. I have my tex file and my bib file. So what do I exactly do to obtain the .bbf file correctly and submit the article?  Thanks a lot!


Sort a list of custom object with String contains in the object

I have a list contains custom object Box. I want to sort the list alphabetically with a String  property of the object Box.  I have tried boxList.sort(), boxList.name.sort(). It does not work.  class Box(object):    name = “”    num = 0    ... box = Box(name, num) boxList.append(box)   I have a list of box in boxList. I want to sort boxList alphabetically by the String name contains in boxList.


Should I use t-test on highly skewed and discrete data?

I have samples from a highly skewed dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want to compare their mean. For that, I'm using two-sample unpaired t-tests(and t-tests with the Welch’s factor, when the samples had different variances). As I have heard that, for really large samples, it doesn't matter that the sample are not normal distributed.  My metrics are discrete, they are counts of the number of each user's participation. Of course we have those users who participate much more than the others, but I'm not considering them as outliers. Here are the data description:   My problem: someone, reviewing what I've done, said that the tests I am using were not suitable for my data. They suggested to log-transform my samples before using the t-tests.  I do know that I can't log-transform these, because all of them have zero-values on the samples. My guess is, if I can't use t-test, I should use the Mann Whitney U test.  Are they wrong? Am I wrong? If they are wrong, is there a book or scientific paper which I could cite/show them? If I am wrong, which test should I use?


I need to access all possible number of combinations of characters in a string. Without Using Any loop, because i have to filter records in thousands. loop can give performance issue.  lets Take a Example :  Any Custom method ABCD ===>> ABCD, ABDC,ACBD,ACDB, ADCB, BACD, BADC, BCAD, BCDA, BDAC , BDCA , CADB,CBDA,CDBA, CBAD, DABC, DBCA, DCBA,DCAB......  thanks in Advance


Prove that $\tan A + \tan B + \tan C = \tan A\tan B\tan C,$ $A+B+C = 180^\circ$

I want to prove  \begin{equation*} \tan A  + \tan B + \tan C = \tan A\tan B\tan C \quad\text{when } A+B+C = 180^\circ \end{equation*}  We know that   \begin{equation*} \tan(A+B) = \frac{\tan A+\tan B}{1-\tan A\tan B}~\text{and that}~A+B = 180^\circ-C. \end{equation*}  Therefore $\tan(A+B) = -\tan C.$ From here, I get stuck. Please help.


Is the field $\mathbb{Q}(3^{1/3},3^{1/4})$ a Galois extension of $\mathbb{Q}$?

My understanding is that for $\mathbb{Q}(3^{1/3},3^{1/4})$ to be a Galois extension of $\mathbb{Q}$ there must exist a polynomial over $\mathbb{Q}$ with roots $3^{1/3},3^{1/4}$ that splits in $\mathbb{Q}(3^{1/3},3^{1/4})$. Is it true then that this field is not a Galois extension in this case as the field does not contain $i$ (since some roots of $x^3-3$ and $x^4-3$ are complex) or am I missing the point?   Thanks.


So I've been cleaning up my desktop for the last few minutes, and I tried to delete this empty folder, but it has some 3.46GB of data in it!  Any ideas of why this is happening? I restarted my computer, thinking it was just some kind of fluke, but it is still happening.   (Click image to enlarge)


LaTeX not hyphenating properly, text running off page

I'm having a problem with LaTeX not hyphenating $\beta$-galactosidase, and the word as a result running off the page.  I have narrowed down the problem to a particular package, as a bare minumum LaTeX preamble with no packages avoids this problem.  Please help me to identify the offending package by process of elimination, and suggest a solution that retains the use of the package where possible.  \documentclass[a4paper,12pt]{article}  \usepackage[a4paper]{geometry}  \begin{document} Finally, all of the three antibiotics examined had a negative effect on $\beta$-galactosidase activity from the time they were introduced to the assay.  It is to be noted that chloramphenicol interferes with the 50S ribosomal subunit which negatively implicates peptide bond formation~\cite{chloram1962}, streptomycin interrupts the initiation stage of protein synthesis~\cite{strepto1968}, while rifampicin is an RNA-polymerase inhibitor~\cite{rifam1983}.  These results verify that both transcription and translation are needed for the gene product $\beta$-galactosidase to arise, which is probably not much more than a validation of the flow of genetic information in accordance with central dogma.  An interruption at the transcription or translational stage would prematurely or directly halt the production of $\beta$-galactosidase, in the two respective cases. \end{document}   Sample output:


Concerns about moving media files to a CDN and impact on SEO

I'd like to move all my media files to a CDN (Windows Azure is my best choice for now).   Two questions :   How can I avoid SEO and redirections issues for the previously uploaded media files ? For the next media files I'll upload, isn't using a CDN bad for SEO and search engine ranking ?


Is it correct to say that, in the Bias-Variance trade-off:  the bias error represents the ability of the model to possibly map the trend of the training set ?   and the variance represents how much the model is prone to variations if the dataset changes ?


Can statistical mechanics explain the second law completely?

Statistical mechanics is restricted to the postulate of the equal a priori probability, but this postulate does not need to be considered for thermodynamics, so the valid ranges of statistical mechanics and the second law of thermodynamics are different.  For example, consider a freely falling body, the potential energy of the body is converted into the kinetic energy of random motion in the process, the driving force of the process does not satisfy the condition of the postulate of the equal a priori probability, it is easy to calculate the change of the entropy of the process by thermodynamics.   The question is: Can anyone calculate the change of the entropy of the process by statistical mechanics?


I hope somebody has already figured this one out. I just installed Geoserver 2.9 on a vanilla Ubuntu 16.04 distro. The Geoserver 2.8 method of enabling CORS with the shanbe.hezoun class does no longer work with Jetty 9.2.13.  There are mentions that CORS support is already packaged with Jetty 9.2.13 in the jetty-servlets.jar.  The Jetty lib which is compiled with Geoserver contains a jetty-servlet-9.2.13.v20150730.jar in geoserver/lib but not jetty-servlets.9.2.13.v20150730.jar. Are these supposed to be the same jar with a different name?  It should be possible to enable CORS either in geoserver/etc/webdefault.xml or in geoserver/webapps/geoserver/WEB-INF/web.xml.  My understanding is that the webdefault.xml is applied first and the web.xml thereafter.  I have tried following filter in both xml. I haven't got as far as adding a filter mapping. Adding the filter alone will cause the Geoserver/Jetty service to not start proper.  <filter>     <filter-name>cross-origin</filter-name>     <filter-class>org.eclipse.jetty.servlets.CrossOriginFilter</filter-class> </filter>


Is there a "SHELL IN PRIVATE" mode for bash?

When I use a browser, I can "browse in private" if I don't want my browser history recorded on the local machine.  But what if I'm typing commands in the bash shell and maybe passwords, and I don't want that stored in my command history, but at the same time I don't want to wipe out my command history?  Is there a way to do that?


proof that translation of a function converges to function in $L^1$

Let $f \in L^1(\mathbb{R})$, for $a\in \mathbb{R}$ let $f_a(x)=f(x-a)$, prove that: $$\lim_{a\rightarrow 0}\|f_a -f \|_1=0$$  I know that there exists $g\in C(\mathbb{R})$ s.t $\|f-g\|_1 \leq \epsilon$, this is also true for $f_a$ and $g_a$.  Now I have the next estimation:  \begin{align*} \|f_a-f\|_1 &= \int_{\mathbb{R}} |f(x)-f(x-a)| dx \\ &= \int |f(x)-g(x)+g(x)-g(x-a)+g(x-a)-f(x-a)| \\ &\leq \|f-g\|_1 + \|f_a-g_a\|_1 + \int |g(x)-g(x-a)| \end{align*} my question is: I can argue that $\lim_{a\to0} \int |g(x)-g(x-a)| = \lim_{a\to0} \lim_{T\to\infty} |g(x_0)-g(x_0-a)| 2T$, now I think that I can change the order of the limits here, but I am not sure why?  P.s $x_0$ is some point in $[-T,T]$, and the above is valid from the intermediate integral theorem for continuous functions, right?  Thanks.


When users are deleted do you get reputation back from their downvotes?

I've noticed that I've lost some reputation when users are removed, since that's specifically called out in the inbox messages.  However, I am curious if lost reputation from downvotes the user gave are also restored in that situation.  All reputation lost due to deleted user accounts were evenly divisible by 5 so it doesn't appear to be the case.  (i.e. you gained +4 reputation because a user was deleted).  I only ask because in a particular question I answered it appeared as if someone went through and downvoted the question and each answer for no apparent reason.  Looks as if someone can damage your reputation and you can never get that back.  For me personally, I have enough reputation that the amount lost isn't that much but for someone just getting started it could be a problem.  The suggested duplicate did not cover the reputation change related to downvotes specifically so that was an open question.  Based on my observations the few times I had reputation changes due to users being deleted I never had a rep change value that would suggest downvotes were being restored.  Maybe they never downvoted me, or maybe the number of downvotes always ended up being a multiple of 10.  It was clear about the removal of upvotes though.


I have a question about coding style / indentation and alignment, and I don't know where (or if) there is a Stack Exchange site suitable for that.  I only figured that it would not be an o.k. question for Stack Overflow, because it is both off-topic and primarily opinion based, and I don't think it's suitable for Code Review either.    A sample question:  How should I align the following long construct to make it a little more readable?  return LongClassName.DoSomething<TReturn, TExceptionOnFailure, TPassedData>(myReturn, new MyException(), this.helper.Data);     Where can I ask such questions?


Need some advise on pitching Ubuntu SBS and desktops for my company

In the next couple of weeks I need to present an IT presentation for future I equipment for the small company I would with.  The have been shrouded by the Microsoft and Apple blanket and introducing Ubuntu to them is going to be a tough task.  Can anyone give me some advise who has had the task of pitching Ubuntu for business being the favourable OS over Windows which they are currently using?  I will say none of them are tech-savvy and some of them don't even know how to send emails.  Any advice would be gratefully appreciated.


I'm trying to learn classes in C++ but i'm unable to understand what's happening here. #include<iostream> #include<string>  class Dummy{      public:         std::string name;         void setName(std::string input){             name = input;         } };  int main(){     Dummy obj;     obj.setName("John");      Dummy obj1(); // error in this line     obj1.setName("John"); }  Error: prog.cpp: In function ‘int main()’: prog.cpp:18:10: error: request for member ‘setName’ in ‘obj1’, which is of non-class type ‘Dummy()’    18 |     obj1.setName("John");       |          ^~~~~~~


Show that: $\lim_{n \to \infty}\prod_{k=1}^n \cos(k\sqrt{\frac{3}{n^3}} t) = e^{- \frac{t^2}{2}}$

Is it true that $$\lim_{n \to \infty}\prod_{k=1}^n  \cos\left(k\sqrt{\frac{3}{n^3}} t\right) = e^{- \frac{t^2}{2}}$$ ? How to proceed ?


How to install Oracle Java on Ubuntu 14.04?

I am using Ubuntu 14.04.1 LTS, x64 architecture, and I specifically need to install . Now I know there are some  on the website which I follow but the same website does not . Can any one please help me with some instructions? Thanks!


Question 1: Why are irrational numbers uncountable and rationals countable?  I really struggle to understand this. I initially thought it had something to with the fact that between any two numbers there will always be a irrational number. But now it has come to my attention that the same holds for rational numbers. So I can't really see the difference between them. What is it that makes the difference? Why can we line up all rational numbers one-to-one with the natural numbers, but not the irrationals with the naturals?  Sorry for a perhaps basic question, but I really, really struggle with it. Thanks.


There's a film just out called Salmon fishing in the Yemen.  I've also heard people talk about the country Yemen as "the Yemen".  Is it wrong to call Yemen "The Yemen" - or does it date back to some colonial era, where that was what people said?


I am trying to figure out how to configure proper indentation when writing an algorithm in LaTex.  The algorithm code should look like:   Let a = 0 let b = 1 if (a > b)     do action 1 else if (a = b)     do action 2 else      do action 3 all done   I could have more than one level of indentation involved in the algorithms, so it needs to be a flexible solution.  Any suggestions are greatly appreciated.


Why are you required to file your taxes if you employer deducts them for you?

When you work for someone they automatically deduct tax from your pay and give it to the government. Filing your tax returns allows you to get money back if they taxed you too much. So why is not filing your taxes a crime even if you don't make any money from someone other than your employer? If you don't file your taxes the only thing that could happen is the government gets more money than they should, so it doesn't seem reasonable that not taking your money back from the government and letting them keep the extra money is a crime.


I am new to ubuntu.  I purchased (donation) a CD from Canonical in March 2015. The first time I inserted disk in drive and turned on laptop I got an error msg something like "no boot ???? found"  I didn't write it down and could not remember msg.  Laptop is Fuji-Siemens Amilo Li 1705 with Intel(R) Celeron(R) M cpu  440 @1.86GHz and 1.75GB RAM. I am running Windows Vista  Now, when I try to boot with the ubuntu cd laptop tries to read it for about 1 minute and then stops and Windows boots.  If I put CD in while Windows is running, laptop seems to be reading disk for about 1 min and then ejects CD and error msg asks me to insert disk.  Can anyone help please, or should I just ask Canonical  for another CD?


I have a new Lenovo Thinkpad E560, running Windows 7. I installed Ubuntu 16.10, creating partitions for root, home, tmp, and swap. A partition called "bios_grub" was created automatically.  Now whenever I boot the system it boots to Windows 7. My boot menu does not seem to be from grub, it shows only four items:  Windows ATAPI CD0 – boots from DVD ATA HDD0 – does nothing PCI LAN – does nothing   My question is not "how do I install Ubuntu". I have done that several times, without any major problems. This time, however, although Ubuntu has been installed on my disk, it does not appear in the boot menu.  I booted from an Ubuntu live DVD and ran boot-repair but it tells me it cannot deal with a BIOS boot, only UEFI. So I tried to change the Windows boot to UEFI. The result is no booting system at all, with the following message:  File: \EFI\Microsoft\Boot\BCD Status: 0xc000000d Info: An error occurred while attempting the boot configuration data.   When I changed the boot menu back to BIOS Windows worked again. No Ubuntu boot option.  The file \EFI\Microsoft\Boot\BCD exists on the EFI system partition, and the partition is flagged as "boot" and "esp" (shown by gparted). There is no other partion flagged as "boot". The disk is GPT. The Windows partition administration says the partition has status "no errors (EFI system partition)". It is the first partition on the disk.  I see two possible ways to proceed:  (1) Can I change my Windows boot to UEFI, so I can run boot-repair successfully?   (2) Alternatively, is there a way to get a dual boot (grub or whatever) running with BIOS?  Any help is appreciated. Please inform me if there is more information I should provide.    Edit: Output from "sudo lsblk -f":  NAME    FSTYPE    LABEL   … sda ├─sda1    vfat    SYSTEM_DRV                 … ├─sda2 ├─sda3    ntfs    Windows7_OS … ├─sda4    ntfs    Lenovo_Recovery … ├─sda5 ├─sda6    swap … ├─sda7    ext4 … ├─sda8    ext4 … ├─sda9    ext4 … ├─sda10   ext4 … sr0    tso9960    Ubuntu 16.04.1  LTS amd64      … /cdrom loop0    squashfs         …    /rofs   sudo lsblk -fm additionally gives the following sizes:  sda    931.5G sda1   100M     sda2   128M sda3   232.9G sda4   14G sda5   95M sda6   14.9G sda7   9.3G sda8   14.9G sda9   540.2G sda10  105.1G   I installed Ubuntu 16.10 from a live DVD, which I booted via the second item in my boot menu (ATAPI CD0). How can I "start installer in UEFI mode", as oldfred suggested? If I can do that, maybe it resolves my problem.  Sorry, I cannot answer in a comment (size limitation), so I have to edit my original question.    @ubfan1's hint to change my boot options from "BIOS first" to "UEFI first" solved my problem. I re-installed Ubuntu after changing this, and now I have a Grub menu. – ubfan1, if you re-enter this as an answer rather than a comment I will gladly give you credit.


Swap is filling up and shutting down applications, but most of my RAM is free

I have a mac pro with 64 GB of RAM and a 14 GB swap file. I'm running a Jupyter notebook that eats up a lot of memory, so much that the OS is telling me it's out of memory and I need to close applications. When I look at the total memory usage in htop, I see that the swap file is indeed full, but I have almost 40 GB of free RAM!  Why isn't MacOS using the available RAM?  How can I stop it from running out of swap when it has a lot of free RAM?


Using an shell glob (wildcard (*)) after a double quoted variable expansion

I read that it is a best practice to double quote all of your variable expansions in Bash. I also read that one cannot use a shell glob (wildcard(*)) right after a double quoted variable expansion. These situations conflict when one wants use the value of a regex pattern, expanded out of a variable.   The reason I would sometimes want to combine regex with a wildcard is to keep my regex minimal, neater, in my personal taste.  My particular problem  I downloaded phpmyadmin into my document root directory and unzipped it, but I fail to rename it with mv by a regex pattern I put in a variable, and available when expanding its variable. Here's the exact trace:  userName@compName:/var/www/html# ll total 11336 drwxr-xr-x  3 root root     4096 Feb 14 07:04 ./ drwxr-xr-x  3 root root     4096 Feb 14 06:56 ../ -rw-r--r--  1 root root      612 Feb 14 06:57 index.nginx-debian.html drwxr-xr-x 12 root root     4096 Dec 23 08:50 phpMyAdmin-4.7.7-all-languages/ -rw-r--r--  1 root root 11589684 Dec 23 14:08 phpMyAdmin-latest-all-languages.zip userName@compName:/var/www/html# echo $pma [pP][hH][pP][mM][yY][aA][dD][mM][iI][nN] userName@compName:/var/www/html# mv "$pma"*/ phpmyadmin/ mv: cannot stat '[pP][hH][pP][mM][yY][aA][dD][mM][iI][nN]*/': No such file or directory   If I'll unquote the variable expansion to ${pma} I would indeed be able to combine the variable expansion and the regex, as in ${pma}*, but it is important to me to follow the best practice without exceptions, if I can.  My question  How could I keep the variable expansion double quoted, but still using the extracted value with a wildcard?


How to get to the else statement without NullPointerException in my mini library program?

I've created a small program where I have an array of 100 strings (null unless value added using another function). If I am trying to issue a book that is not in the array, it is giving me NullPointerException error, instead of not running the if statement and printing that book isn't found. public void issueBook() {     Scanner sc = new Scanner(System.in);     System.out.print("Enter book title to issue: ");     String BookTitle = sc.nextLine();           //Asks for book name to be compared in the array     for (int i = 0; i < Books.length; i++) {    //loop to check         if (this.Books[i].equals(BookTitle)) {  //if statement to check the condition             System.out.println("Book has been issued.");             this.Books[i] = null; //If the book has been issued, it will null it's position in the array             return;             }         }         System.out.println("ERROR: Book not found.");   //If the book isn't found, it should print this     }


Proving a function is Lipschitz continuous

Show that the following function is Lipschitz continuous and find a Lipschitz constant  $$y\mapsto f(x,y)\\ f(x,y)=\frac{y}{x}\ln(\frac{y}{x})\text{  , } |x-1|\leq\frac{1}{2}\text{  , } |y-e|\leq\frac{e}{2} $$  I have no clue on where to begin to prove this.   My first question is how I should interpret this function, is $x$ a sort of constant?


Let $T$ be a theory, let $L$ be its language, let $A$ be its set of axioms and let $P_0 \in L$ be a property.  $P_0$ could be :   Consequence of $A$ The negation of a consequence of $A$ Independent of $A$   Assume that the property $P_1$ : "$P_0$ is independent of $A$" is also in $L$. Can $P_1$ be itself independent of $A$ ?  For instance, assume $P$ versus $NP$ is independent of the axioms (let's say ZFC), could it be the case that this independence is itself independent of the axioms ? This could explain why nobody already solved this problem.  More generally, assume that $P_{i+1}$ : "$P_i$ is independent of $A$" is also in $L$. Does it exist a property $P_0$ such that $\forall i.\ P_i$ is independent of $A$ ?  If $A$ is empty, any property is independent of the axioms, in particular all the $P_i$ are independent of the axioms whatever is $P_0$.  If $A$ is the axioms of Presburger arithmetic, none of the property is independent of the axioms, but I am not sure that we can express "$P_i$ independent of $A$" in the language of the theory.  What happens when A is ZFC, Peano axioms, Euclide axioms, or any other usual theory ?


Not able to add the fragments using Kotlin Extension function

I have a Kotlin extension function to add a fragment which is in another Kotlin file  fun Fragment.addFragment(tag: String?, id: Int, fragmentManager: FragmentManager) {   // will take care of adding the fragment.   val fragmentTransaction = fragmentManager.beginTransaction()   fragmentTransaction.add(id, this, tag)   fragmentTransaction.addToBackStack(tag)   fragmentTransaction.commit() }   But whenever I am using that extension function to add a fragment then I am getting this crash  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.Fragment.setNextAnim(int)' on a null object reference   I am using that extension function like this:  MyFragment().addFragment("MyFragment", R.id.frame, fragmentMaganer)   After the above statement if I tried to debug my code then its executed successfully till  fragmentTransaction.commit()   but after that in the onStart() method of my activity I am facing that NullPointerException issue  But if I use the same code directly in Activity like this:  val myFragment = MyFragment() val fragmentTransaction = fragmentManager.beginTransaction() fragmentTransaction.add(R.id.frame, myFragment, tag) fragmentTransaction.addToBackStack(tag) fragmentTransaction.commit()   then Its working fine. Can someone please explain why its no working with Extension function?


Say, I am trying to predict likelihood to buy ice cream (event =1 , non-event = 0) using logistic regression.   I have only one variable "Gender" (2 value= Male/Female), so, the formula would be like this.   $logit(p)=β_0+β_1∗female$  Odd ratio for female with reference to $male (A)  = \frac{odd(female)}{odd(male)}$  Next, I added in "TodayWeather" (2 $value = \frac{Sun}{Rain}$).   $logit(p)=β_0+β_1∗female+β_2*SUN$  Q1) Why does the Odd ratio for A with reference to male change? Shouldn't my Odd ratio for female still be the same as (A) above? Since it is still comparing female and male (i.e. the odd of female to buy ice cream if increase by one unit)?  Q2) Say (A) above is < 1, is it possible that once i added "TodayWeather", the odd ratio become > 1? Why?


prove this theorem. Let A be a set. Then ∪P(A)=A. I've tried to do a similar problem but I am unsure how to solve this problem.


Do I need a transit visa if I already have a UK Business visit visa

I currently have a valid UK and US Business visit Visa (Both are multiple entry visa's). I will be travelling to Portugal next month and my flights are from Mumbai through London to finally Porto. My travel agent was booking a ticket for a flight which will be landing in London heathrow airport and then get on another plane from Gatwick airport (with 5 hrs transit  to get to gatwick)... my question is ...do I need get a transit visa or can I manage with the UK business visa which I already have and have been granted a business visit visa to enter UK.... It would be few hours in London just to get to another airport within London. I will be getting a  Schengen visa to enter Portugal. .


Neyman allocation and proportional allocation

Suppose that a city has 90,000 dwelling units, of which 35.000 are houses, 45,000 are apartments,   and 10,000 are condominiums. We want to estimate the overall proportion (p) of households   in which energy conservation is practiced, with a bound on the error of estimation equal 0.1.   The cost for obtaining an observation is \$9 for houses, \$10 for apartment, and \$16 for   condominiums. Suppose that from an earlier study, we know that 47% of house dwellers, 23%   of apartment dwellers, and 3% of condominium residents practice energy conservation.        (a) (4 marks) Using a proportional allocation, find the strata sample sizes, $n_1$, $n_2$, and $n_3$,   and the sample size n.   (b) (4 marks) Using a optimal allocation, find the strata sample sizes, $n_1$, $n_2$, and $n_3$, and   the sample size n.   (c) (4 marks) Using a Neyman allocation, find the strata sample sizes, $n_1$, $n_2$, and $n_3$, and   the sample size n.   Neyman allocation is used when the cost of obtaining an observation is the same for all strata, while proportional allocation is used when costs are unequal among strata but variances are equal in all strata. But in this question, neither cost or variance are equal, then how can I apply the formula for Neyman and proportional allocation? Just ignore the cost and variance and set them equal or is there another formula for that?


Why is meteor speed what it appears to be?

Is the speed of a meteor through our sky because of the speed of the earth's axis  rotation, or because the meteor is speeding towards us at that speed?


Blank desktop on Ubuntu 14.04 (menu missing)

I had to shutdown my laptop unconventionally because of a programm error. Now if I startup I receive just the blue desktop wallpaper, without any menus. Can't even access the terminal. The right mouse button works and behaves normally and I can reach the settings. Something with gnome?  I already tried  sudo apt-get update sudo apt-get install ubuntu-desktop sudo apt-get install unity   from the command line without any success.  I also tried:  sudo apt-get install --reinstall ubuntu-desktop


The following code is not compiled.  I got it out of the manual.  Please tell me what is wrong with it. Also, please tell me where in the manual the options in the command node(b)[circle, draw]{A circle}; are explained.  \documentclass{amsart} \usepackage{tikz} \usetikzlibrary{calc,angles,positioning,intersections,quotes,decorations.markings}   \usepackage{pgfplots} \pgfplotsset{compat=1.11}   \begin{document}  \begin{tikzpicture}  \path (0,0) node(a)[ellipse, rotate=10, draw]{An ellipse} (3,-1) node(b)[circle, draw]{A circle}; \draw[thick](node cs:name=a) -- (node cs:name=b); \end{tikzpicture}   \end{document}


Are stackoverflow pages ( such as Questions, main pages of a posted question, profile page) auto-update?    If so, what is the update interval?


Users should be able to participate in deleting their own closed questions

Before you vote to close: there are a lot of questions with titles and/or bodies that are similar to this one. However, none of the ones I saw deal with this particular case.    I have an  that is appropriately closed as a duplicate of an FAQ entry. I just tried to delete it because it doesn't really add any useful search terms or overall value to MSO. I got the following message:     Sorry, this question has answers and cannot be deleted; flag it for moderator attention instead.   That's the same message that comes up when you try to delete your own unclosed answered questions. Since I'm a 10k user, I think the system should at least allow me to cast a regular, non-binding delete vote for that post, if not delete it unilaterally.  I also think that 20k users attempting to delete their own recently closed posts shouldn't have to wait through the 48-hour "possible reopening" period, but since my example question was closed over a year ago I don't know what the system actually does.


How to create a matrix with 20 columns in latex

The code below works,  but when I add 10 more columns, it does not. So, how can I add ten more columns to the matrix below?  \documentclass{article} \usepackage{amsmath} \begin{document}  \begin{equation} \begin{bmatrix}  1 & 0 & 0 & 0  & 0 & 1 & 0 & 0 & 1 & 0  \end{bmatrix} \end{equation}  \end{document}


Are sounds louder at night, in the winter?

Surface temperatures of -40C and +40C are not unheard of in habitable areas on Earth. That's a variation of over 30% in density (for a given barometric pressure).  Does that mean that for the same event (dropping something) or the same setting on a volume control, the sound level one hears can vary by 30% over this temperature range?


In the beginning of the story the Main character wakes up from what I believe is a tomb. In this world people have different colored eyes depending on the believe their attributes. Before the Main character went to sleep Golden eyes which the main character has are considered demon eyes because the demons had those color eyes and could control magic better. However, after he comes out of his slumber the golden eyes are seen as the weakest of all the colored eyes. Also a Demon girl that he rescued before going to sleep has been waiting for him all this time to wake up.


How to use SAGA Kriging in Sextante for QGIS?

Hello, I tried to use SAGA (Ordinary Kriging) via SEXTANTE in QGis. The Sextante log tells me the following problem. Does anyone have a solution for my problem? By the way I'm usually a SAGA user but I wanted to change to QGis.   Grid: [not set] Variance: [not set] Points: HERBST_Nuptake_Fert120 Attribute: NUPTAKE Create Variance Grid: yes Target Grid: user defined Variogram Model: Spherical Model Block Kriging: yes Block Size: 100.000000 Logarithmic Transformation: yes Nugget: 0.000000 Sill: 10.000000 Range: 100.000000 Linear Regression: 1.000000 Exponential Regression: 0.100000 Power Function - A: 1.000000 Power Function - B: 0.500000 Maximum Search Radius (map units): 1000.000000 Min./Max. Number of m_Points: [4.000000] - [20.000000]  error: executing module [Ordinary Kriging]  C:\Programme\Quantum GIS Lisboa>saga_cmd io_gdal 1 -GRIDS "C:\Dokumente und Einstellungen\user\sextante\tempdata\test.tif.sgrd" -FORMAT 1 -TYPE 0 -FILE "C:\Dokumente und Einstellungen\user\sextante\tempdata\test.tif"    ##   #####  ###  ##  # ## ##  #### #  ##### ##    #  #   ##  ##### #    library path:   D:\Programme\SAGA_Beta\saga_208\modules library name:   io_gdal module name :   GDAL: Export Raster author      :   O.Conrad (c) 2007    go...  Load grid: C:\Dokumente und Einstellungen\user\sextante\tempdata\test.tif.sgrd...  failed  error: Grid file could not be opened.


Software vs. Hardware Appliance DDOS & Firewalls

I run several Ubuntu Servers (virtualized) and have fail2ban installed for DDOS mitigation. For a firewall, each server has iptables.  I'm evaluating my security options and was wondering how well fail2ban protects you from DDOS attacks vs. a dedicated hardware appliance? And, is a hardware firewall going to provide you better/more protection than iptables (or is it just higher up in the stack)?


We know that the correct order of declaring variables in structures changes the size of a structure also because of padding. I have seen the reference .  Suppose a structure is:  struct s {     char b; //1 for char     char c; //1 for char + 2 for padding     int a; //4 for int }my_struct;   So the size of the my_struct is 8, but without padding it could be 6 which is less than 8.  So my question is: Why padding is done in structures? What is the necessity of this concept?  Because without padding the structure is of lesser size. My question is not related to when padding take place, it is more concerned about the concept of padding.


string[] columns   I want to delete the item on an index specified by a variable of type int.  How do I do this ?  I tried  columns.RemoveAt(MY_INT_HERE);   But apparently this does not works.


Python Equivalent To PHP True False line

In PHP, you would do something like:  $answer = ($x != null) ? true : false   instead of doing:  if($x != null) {      $answer = true; } else {     $answer = false; }   Is there anyway to do this in python? I've tried to google and to search in here but I couldn't find anything, plus google doesn't take symbols into searching.  You might say, why didn't you google search it by name? Well I do not know what that type of line code is called.


Throw an error preventing a table update in a MySQL trigger

If I have a trigger before the update on a table, how can I throw an error that prevents the update on that table?


What is the role of the logarithm in Shannon's entropy?

is the negative of the sum of the probabilities of each outcome multiplied by the logarithm of probabilities for each outcome. What purpose does the logarithm serve in this equation?  An intuitive or visual answer (as opposed to a deeply mathematical answer) will be given bonus points!


What does the writer mean by saing "said teeth"?

Toothaches are awful, aren't they? In fact, they are really high up there on the "pain scale" -- at least in my mind (and the minds of many patients that I see). I mean, think about it -- they are painful enough to drive someone to go see a professional who will drill (drill!) into said teeth (amongst other things). So yes, toothaches hurt.  I can't get its meaning or use.


How come a python file is executable even though its permissions are 644?

I think I am misunderstanding something here. I have made an easy python testing file to see how permissions affect the use of python files. I did so in order to be able to answer   SetUp  I have made a test.py file with the contents  print 'I am working'   Test case 1  ls -al test.py  -rw-r--r-- 1 joey joey 25 Dec 24 11:11 test.py python test.py I am working    How come python is executing this file even though I did not do chmod +x test.py?   Test case 2  chmod 400 test.py ls -al test.py  -r-------- 1 joey joey 25 Dec 24 11:11 test.py python test.py I am working   So apparently python only needs read permission in order to execute my file?  Test case 3  chmod 200 test.py ls -al test.py  --w------- 1 joey joey 25 Dec 24 11:11 test.py python test.py python: can't open file 'testo.py': [Errno 13] Permission denied   Write permissions are insufficient (and for the record, only executable permissions are insufficient as well).   How come python executes files without executable permissions?


What is the difference between Ubuntu and its derivatives?

What different Ubuntu derivatives are there? And what is special with them?


Toilet does full-blast, one-second refill every hour or so

I wouldn't lose sleep over this, except the unexpected and fierce sound startles my girlfriend and cat every time.  So I just replaced the refill valve on our toilet (using a kit, so everything from the lock nut to the overflow spout, but not the plunger or handle).  It works great. No signs of leaking (at least not on the floor or walls). It does a full refill every time right up to the refill line printed on the back of the tank. The overflow spout is above, not inside, the overflow pipe.  Every so often (maybe once an hour), the toilet shrieks for a half-second, like the float drops just enough to cut on the flow and then rises with just a squirt of water.  My first thought was evaporation, but 1) I'm surprised it's that sensitive and 2) I know our old fill valve didn't do this (at least I don't remember it doing it, and I'm sure both gf and cat would have mentioned it if it did).  The one thing I didn't tweak was the water level screw, because the critical point line and overflow pipe were the specified 1 inch apart (eyeballed) and the water fills to exactly the above-mentioned line.  If it is the water level, is this spontaneous and short burst indicative of needing to lower or raise the water level?  And can someone explain why it happens at all? I imagine the water-level adjustment changes where the float "floats" so if the water level is where it should be after a refill, why would it run 30-60 minutes later for a short burst?


Why does arXiv have a multi-day lag between submission and publication?

If you go on the  (now, 8th December 2020, 19:24 Italian time), there is for example the article "Exploring the Usage of Online Food Delivery Data for Intra-Urban Job and Housing Mobility Detection and Characterization". This article is under the heading "8 December". But if you , it was "Submitted on 4 Dec 2020". Why there is a lag between submission time and the header under which it appears for recent publications? I guess the arXiv staff have to approve the article before is being published .... is my guessing correct?


What direction to walk in to capture a targeted Pokemon?

There is a list of the nearby Pokemon and some approximate idea of the distance. But after I choose one, how do I actually walk towards it? Is there a way to see the Pokemon on the map or some direction indicator to follow?


Book where humans on another planets are cannibals

Trying to remember the name/author of a book:   Long book. Many many separate small chapters. Scifi about humans, on non-Earth planet. They have poisonous native life, and can only eat a few brought from Earth plants. Because of that, they practice cannibalism, to no waste human body proteins. The story opened with consuming a body of someone who recently died. It had a pretty complex plot, with politics, war, technology, social structures, etc.  Social/sexual customs were kind of weird even leaving aside rituals around cannibalism. But it was NOT Heinlein, I'm sure of that :)   I don't know the year it was published, but it was pretty old, I took it around 1993-95 from a library and the physical book looked well-read by that time.


make: *** No rule to make target 'install'. when trying to install xmr-stak

First I would like to say that I am new to Ubuntu and Linux.  I get an error with the make install when following the below instructions to install a Linux version of cpuminer-multi.     make: No rule to make target 'install'.  Stop.   I have placed what is in the folder that gets created when I attempt to install at the end. What am I missing?    SCRIPTS USED  sudo add-apt-repository ppa:ubuntu-toolchain-r/test sudo apt update sudo apt install gcc-5 g++-5 make sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-5 1 --slave /usr/bin/g++ g++ /usr/bin/g++-5 curl -L http://www.cmake.org/files/v3.4/cmake-3.4.1.tar.gz | tar -xvzf - -C /tmp/## Heading ## cd /tmp/cmake-3.4.1/ && ./configure && make && sudo make install && cd - sudo update-alternatives --install /usr/bin/cmake cmake /usr/local/bin/cmake 1 --force sudo apt install libmicrohttpd-dev libssl-dev libhwloc-dev git clone https://github.com/fireice-uk/xmr-stak.git mkdir xmr-stak/build cd xmr-stak/build cmake .. make install     FILES/FOLDERS GENERATED  build CMakeLists.txt doc LICENSE scripts xmrstak CI CONTRIBUTING.md Dockerfile README.md THIRD-PARTY-LICENSES


How would you explain mathematical induction to a novice in a simple and intuitive way?

How would you explain induction to a novice in a way that's simple and easy to comprehend? I'm a believer that the mark of someone who understands a topic well is their ability to communicate that topic with ease and simplicity. I think this post is an opportunity for us to exercise our imagination, our intuition, teaching, and communication skills in a rigorous subject matter. Moreover, it could be great place for someone who is struggling to grasp induction to get clarity and insight. I'm interested to see how we can explain this idea without getting too muddled with jargon and notation.


Java Regex match first occurrence of dot

In this string: jdbc:sqlserver://testserver.apple.com\A4534:54623 I want to match "testserver" "apple.com//A4534" and "54623" Regex:  jdbc:sqlserver:(.+)\.(.+):(.+) But I get, "testserver.apple" "com//A4534" and "54623"


If $H,K⊲G$ and $H∩K = \{1_G\}$, then all elements in $H$ commute with all elements in $K$

Let $H,K⊲G$ be two normal subgroups such that $H∩K = \{1_G\}$. Prove all elements in $H$ commute with all elements in $K$.  I have no idea how to do this.


Show that a division ring is simple.   With a division ring I mean a ring such that all onzero elements are invertible. And with a simple ring I mean a ring which has exactly two two-sided ideals.  I'm doing some exercises to prepare for a new course that start next week. I'm trying to get my ring theory neurons back in the shape they used to be 6 months ago


limit $\lim_{n\to \infty }\sum_{k=1}^{n}\frac{k}{k^2+n^2}$

How do I evaluate this?  $$\lim_{n\to \infty }\sum_{k=1}^{n}\frac{k}{k^2+n^2}$$  I got concerned for that, I've tried make it integral for Riemann but it still undone.


I recently ordered a batch of halloumi cheese online. It was packaged as fist-sized, vacuum-sealed pieces with a little liquid in each (brine I guess). It is supposed to be refrigerated, and the package had a gel pack for cooling. Unfortunately, the package was delayed by over a week, as the postal carrier mixed up. So I will have to assume that the halloumi has been sitting at room temperature for over a week. Should I be concerned about any food safety issues here (botulism etc.)? Especially anything that does not go away by grilling/frying? EDIT: I am aware of the two-hour rule etc., but that rule would already be violated if the package had arrived on time, as I cannot imagine that a little gel pack would keep temperatures in the safe zone for two days in a cardboard box sent halfway across the country (no special isolation or anything). I am really asking about the specifics of this particular food item.


A or an before slash phrase? A or an before parenthetical phrase equivalent to slash phrase?

NOT A DUPLICATE!  The other question only asks about parenthetical phrases, not slash phrases.  The other question's parenthetical phrase (answer(s) explained that it's not really a parenthetical phrase) is a separate word. Mine is an intra-word parenthetical prefix. That's different!       Extreme votes on a Stack Exchange post often indicates that there was a(n) (dis)agreement.        When you see spam on Stack Exchange, you should cast a(n) upvote/flag.        The ship traveled across a(n) sea/ocean.   The first example's parenthetical thingymajigger is equivalent to the slash phrase "agreement/disagreement."  What's the correct singular indefinite article to use before slash phrase (this/that) and parenthetical phrases ((a)sexual, (de)criminalize)?


I would like an alternative for the word "pedantic". "Pedantic" has the meaning of :     highly concerned with minute details or formalisms, especially in learning or teaching.   The problem is, "pedantic" is used in a negative way, that is, it is used for some one who is "ostentatious, and overly concerned". I would like to have a word that has the same meaning as this word(concerned with minute details), minus the negative connotations.   Some come to mind:   meticulous, but "meticulous" can also be used for habits, such as meticulous habits in tidiness etc. scholarly, but "scholarly" although used for study, does not necessarily have the connotation of highly meticulous study. It can just be study of a subject, without going in-depth.   Ideas please?


I have a problem with rounding. I need a 6 decimal precision and in "spoj" i get a good result, but the cout or printf round my outcome to 2 decimals. I tried using printf but still console rounds my outcome.  How can i avoid this?  #include <iomanip> #include <string>  void spoj(double** tab, double* vector, int columns, int rows) {     double** tab_t = new double* [columns];     for (int i = 0; i < columns; i++)     {         tab_t[i] = new double[rows];     }      for (int i = 0; i < columns; i++)     {         for (int j = 0; j < rows; j++)         {             tab_t[i][j] = tab[j][i];         }     }     //for (int i = 0; i < columns; i++)     //{     //  for (int j = 0; j < rows; j++)     //  {     //      std::cout << tab_t[i][j] << " ";     //  }     //  std::cout << "\n";     //}      double* outcome = new double[columns];     for (int i = 0; i < columns; i++)     {         outcome[i] = 0;         for (int j = 0; j < rows; j++)         {             outcome[i] += tab_t[i][j] * vector[j];         }     }      for (int i = 0; i < columns; i++)     {         printf("%.6f", outcome[i]);         std::cout << " ";     } }


Which board is proper to describe the state of any shop/restaurant?  For instance,     A restaurant with the board Close OR Closed?    A restaurant with the board Open OR Opened?   Well, if I think 'closed' is used when the restaurant is permanently or temporarily closed for more than a day (say for holidays or renovation), what about the conversation mentioned below? It takes -ed even for that day!     "Hey Mike, I forgot my specs at home. Do you see the restaurant there at distance? Is it open?   "Yeah, I do see. But it's closed.   I think open/opened or close/closed here is not a verb. If it isn't, then what is it in those examples?


I am fairly new to blender and I cannot seem to solve this issue;  Whenever I add a new object. I used to get this sort of menu. in the tools section on the right.    However, after working on my file for about an hour. I cannot access this menu upon adding a new object.


MYSQL JOIN 2 tables and return comma separated field

I have two tables:  appointments_recurring_forever  id | text  1 | some text here   2 | other text  3 | third appt text  recurring_appointments_exclude_dates  id | appt_id | date  1 | 1       | 2019-01-01  1 | 1       | 2019-05-21  2 | 2       | 2020-11-05   I want to join these two tables based on the appointment id, but my expected result needs to look like this:  appt_id | text           | excluded_dates  1      | some text here | 2019-01-01, 2019-05-21  2      | other text     | 2020-11-05  3      | third text     | null   I know how to create joins, but how to does one create a select that joins based on the appt_id while creating a comma separated concatenated row of the excluded dates?    This is what I can do so far...  SELECT appts.id AS appt_id, appts.text  FROM appointments_recurring_forever appts LEFT JOIN recurring_appointments_exclude_dates ex_date ON ex_date.appt_id =  appts.id   Thank you for any help.


Let $(a_n)_n$ be a sequence in $\mathbb C$ such that for any sequence $(x_n)_n \in c_0$ the sum $\sum a_nx_n$ is convergent. Show that $(a_n)_n$ is in $l^1$  I have shown $(a_n)_n$ is in $l^p$ for all $p>1$. I was trying to figure out what goes wrong for the sequence $(1/n)$ in which case we get a concrete $x_n=1/(log{ }n)$. So how do I do this general case ?  EDIT: Since there were some comments regarding duplicates of some post let me post an approach I was trying  We know $c_0^*=l^1$ so if $(a_n)_n$ is not in $l^1$ the functional from $c_0 \rightarrow \mathbb K$ given by $(x_n)_n \mapsto \sum a_nx_n $ is unbounded and hence we will get a sequence of sequences say $(x_{n,k})_n$ such that $ |x_{n,k}|<1/k$ $ \forall n$ but $\sum a_{n,k}x_n > \epsilon \forall k $ (after possibly multiplying by $e^{i\theta_k}$ )  Consider the sequence $(z_n)_n$ given by $z_n=\sum_{k} \frac {x_{n,k}}{k}$. Using DCT it is easy to see that $lim_{n\to \infty} z_n =lim_{n\to \infty} \sum_{k}\frac{x_{n,k}}{k}=0 $ and hence $(z_n)_n\in c_0$ but $\sum a_nz_n> \epsilon \sum 1/k$ which goes to infinity. But the catch is in the last part. Any insight will be helpful.


I've been experiencing a rather unusual problem lately. Sometimes I leave the computer on for a number of days before shutting it down if I don't plan to use it again within the next 8 hours. So it's usually on during the weekend and shutdown during the workday.  This past Thursday (2 days ago) I booted it up. The PC has a BIOS password that must be entered before Windows loads. Friday evening, the computer crashed, and as this is an old PC, that is not unusual in and of itself. Usually the entire display just freezes up and I can usually tell in the seconds leading up to the freeze that it will. This time, the video card just appeared to die all of a sudden, and the monitor stopped getting input from the computer. Usually I pull the plug to restart but this time the PC after a few minutes shut off by itself. I pressed the power button and it proceeded to the BIOS password screen, indicating yes it had shutoff.  I yanked the power again then and didn't actually boot up the PC until just this afternoon. And I could not have been more surprised. After the BIOS screen, Windows resumed as my session had been before it crashed! This has not happened before! Usually, all my work is lost. This time, all the Word documents that had been open were still open, and even the video open in my incognito Chrome window was still open to where it had been!  I am very upset about this, as if a computer loses power, there is no way a session should be restored. I believe the time the PC last crashed before yesterday was Wednesday, the day before I booted it up on Thursday.  It almost seems like the computer hibernated, yet the computer crashed.  I went and looked at the system uptime and found something even stranger. According to Windows, as of right now, the computer was last turned on this past Sunday, March 25th (today is Saturday the 31st). Yet, I shut the computer down normally on Tuesday, and it crashed "normally" on Wednesday and then crashed again on Friday in a way that all my windows reappeared completely undisturbed when I booted the PC up again today.     Hibernate and sleep are disabled, so I am not sure why this could occur.  Is there any way to prevent this from happening again? I would like to be certain that if the computer crashes, my work IS lost and my previous session does not suddenly get restored. I am not comfortable with Windows being able to restore my session after it has crashed unexpectantly, especially if I cut power. This is a major security hazard.  Further, could anyone explain how and why Windows thinks the computer has been on since Sunday, when it has been shutdown or crashed at least three times during the week? How can I ensure that when Windows shuts down, it is really shutting down and not performing some pseudoshutdown as evidenced by Task Manager and Command Prompt?


How do you become a "Trusted Community Member"?

When I submit a suggested edit, a notice would say that my edit "Won't be viewable to other people until it is approved by trusted community members" (sorry if I did a quotation mistake), but it doesn't specify how much reputation is required to become a "trusted community member."


Lattice based cryptography: How do negative coefficients in $Z_q[x]/(X^n+1)$ work?

I saw that in lattice-based cryptography schemes, for example , coefficients in $Z_q$ are allowed to be negative. For example, in Dilithium the secret key is $s_1 \in R_q^{k \times l}$, where $R_q = Z_q[X]/(X^n+1)$. In the reference implementation and also in the paper, all coefficients for $s$ are in the range $\{-2,\dots,+2\}$, so they explicitly allow negative numbers. So far I was the impression that $Z_q = \{0, \dots, q-1\}$, but it seems lattice-based cryptography often also allows negative numbers. How does the arithmetic (i.e. addition) work when also negative numbers are allowed? And what terms would I need to look up to read up about the underlying mathematical concepts used when also negative numbers are allowed?


Yesterday I downvoted on an answer, and posted a comment explaining why I disagree with the answer.  The author of the answer replied to my comment, and his reply convinced me that the answer was reasonable. Now I would like to remove my downvote, but I can't because it's locked in. What is the sense in that?


I came across a theorem used to calculate residues of rational functions that states that if f and g are analytic functions at $z_k$ and $g'(z_k)$ isn't 0, then the residue of $f(z)/g(z)$ at $z_k$ is $f(z_k)/g'(z_k)$. I want to prove this using Laurent series (taking out the coefficient of $(z-z_k)^-1$) but I can't get around the algebra of actually dividing the two Laurent series. Can someone guide me through this?


Test accuracy much lower than train and validation

I have 2 million samples and using a 60/20/20 split for train, validation and test. Validation and train accuracy are very close to each other at 80% and 85% respectively but test accuracy much lower at 55%. I know that we aren't supposed to monitor the test losses for each epoch but I checked and the test loss was increasing after 10 epochs but train and validation losses were both decreasing. What am I doing wrong?


Find out which raster has highest values

I have 3 rasters for water use and 1 raster for water supply.   I want to know which one has the highest values which will mean that it has the greatest influence on available water supply.  What tools can I use for this in arcmap 10.0 and how do I do this?


How to make this heart (♥) using keyboard?

On windows I have always used the "ALT+3" for creating a wonderful heart for expressing my love...    Is there a way to do this on Ubuntu?


Can an Animagus take the form of any animal?

Similar to my old question about  are there any limits to the animal forms an Animagus can be?     We know that the animal form can be much smaller than human (cat, rat, beetle) so I don't think size is a factor.   I'm not aware of any Animagus who transforms into a magical creature (e.g. unicorn or phoenix) so maybe those aren't possible.   Ultimately, what I'd like to know is whether there could be a T-Rex Animagus... (prompted by )


Convergence of a sequence of non-negative real numbers $x_n$ given that $x_{n+1} \leq x_n + 1/n^2$.

Let $x_n$ be a sequence of the type described above. It is not monotonic in general, so boundedness won't help. So, it seems as if I should show it's Cauchy. A wrong way to do this would be as follows (I'm on a mobile device, so I can't type absolute values. Bear with me.) $$\left|x_{n+1} - x_n\right| \leq \frac{1}{n^2}.$$ So, we have $$ \left|x_m -x_n\right| \leq \sum_{k=n}^{m} \frac{1}{k^2}$$ which is itself Cauchy, etc., etc. But, of course, I can't just use absolute values like that. One thing I have shown is that $x_n$ is bounded. Inductively, one may show $$ \limsup_{n \to \infty} x_n \leq x_k + \sum_{k=n}^{\infty} \frac{1}{k^2},$$ although I'm not sure this helps or matters at all. Thanks in advance.  Disclaimer I've noticed that asking a large number of questions in quick succession on this site is often frowned upon, especially when little or no effort has been given by the asker. However, I am preparing for a large test in a few days and will be sifting through dozens of problems. Therefore, I may post a couple a day. I will only do so when I have made some initial, meaningful progress. Thanks.


Trying to build a circuit for quantum teleportation on IBMQ I get ERROR_RUNNING_JOB error

I am trying to build a circuit for quantum teleportation. On the simulator, everything runs fine and according to expectations, however, I am not able to run the algorithm on the real quantum processor.  ERROR_RUNNING_JOB is returned without any other explanation. I tried to implement two different circuits, the first one with controlled X and Z gates, the second one with gates X and Z are controlled by a value in the classical register. Please find both circuits below.  I appreciate any help.  Thanks.


event.preventdefault() doesn't work in some places

Ahoy! I am writing a small json based database website as a school project. I am having the following problem with my code.  I want to make a link on the page that loads new content without refreshing the page. To serve this process i am using  tags with the jquery code to prevent the links from refreshing the page as shown below:  $("#sorter").click(function (e) {     e.preventDefault();     name = look_for_index($("#artist_input").val(), artist_lite_dict, "name");     global.load_artist(); });   In the case above this works, However in the case below this it just refuses to work at all and i have no idea why. i have tried getting everyone i know who knows Js to help me but people just leave confused. "code below":  $(".art").click(function(e){     console.log("CLICK");     e.preventDefault();     name = this.parent().sibling(".title").val()     title = this.children(span).val();     look_for_index(name, artist_full_dict, "name")     global.print_art(title); });   And the HTML that relates to this code is generated in javascript but here are the template objects if the bug is html related:  const art_list_template = ({     title,     date,     index }) => `
                          ${title}
             Date: ${date}, Index: ${index}

 `   link to the whole project on github:   -Thanks!, Stephan


Find elements $f,g\in\mathrm{End}(V)$ such that $f\circ g=id_V$ and $f,g\not\in \mathrm{End}(V)^{\times}$

Let $K$ be a field. Given $V$ a $K$ vector-space containing all sequences $a=(a_n)_{n\in \mathbb N}$ with values from $K$, such that $a_n\neq 0$ for only finitely many $n\in \mathbb N$.  I want to to find $f,g\in\mathrm{End}(V)$ such that $f\circ g=id_V$ and $f,g\not\in\mathrm{End}(V)^{\times}.$


Will Ubuntu 13.10 work fine on my netbook?? or should i choose some previos version?

I'm new to Linux, just downloaded Ubuntu 13.10 and finally decided to switch to Linux.  Is My Hp Mini Net book with Intel(R) Atom CPU N455 @ 1.67 Ghz , 2GB RAM fine to run this OS smoothly or should i choose someone else? I mean won't I be missing the new fun going on Linux if i choose older one.?


I just received the following comment from an Elsevier editor "The manuscript does not reach the required quality standard of this journal.". To my mind say just that or nothing is pretty much the same considering the minimum requirements for data openness and transparency. there is already a good explanation of the submission process here:  However, as an automated process, is prone to flaws as well as to improvements. And does not explain in detail the received comment stated above. Any thoughts on deciphering the comment stated above are greatly appreciated. thank you EDIT: When I posted this question I forgot to add an essential and relevant fact to this conversion, which is: many and many scientific researchers don't have the opportunity to develop their research works in a team or even do it collaboratively. They have to rely on themselves to present their findings and defend their thesis. And everyone here is acquainted with the syndrome of  "tunnel effect" when writing. So having someone, that can give a small contribution to unlocking someone else research writing, I see as a welcoming behavior that can only benefit the scientific community at the individual level.


How to add data into a dictionary from two lists

I have two lists  teams = [ India, Australia, England ] ratings = [ 12, 16, 11 ]   I want a dictionary like this   dict = { 'India':12, 'Australia':16, 'England':11}   I was trying to get it through looping elements of the first list, but I can't add two counters.  len1 = len(teams) for x in range(1, len1):     dict1[x] = rating     print dict1   How do I create this dictionary?


It seems that the    , and      are largely the same, with the notable exception that Debug usage is compiled out in a release configuration.    When would you use one and not the other?  The only answer to this I've dug up so far is just that you use the Debug class to generate output that you only see in debug configuration, and Trace will remain in a release configuration, but that doesn't really answer the question in my head.  If you're going to instrument your code, why would you ever use Debug, since Trace can be turned off without a recompile?


smallest number larger than x with sum of digits y

let us suppose that we have a number x and we need to find the smallest number larger than x who sum of digits are y. As an example lets take 3 as x and we need to find a number larger than x for which sum of digits is 2 and the answer is 11 . what should be the strategy ? I GOT this while solving a problem  .can i get an example of how to solve this ?                                                                                iterate through the digits of y from right to left, trying to                  increase the current digit and somehow change the digits to the right in order to reach the sum of digits equal to x. Note that if we are considering the (k + 1)-th digit from the right and increase it, we can make the sum of k least significant digits to be any number between 0 and 9k. When we find such position, that increasing a digit in it and changing the least significant digits gives us a number with sum of digits x, we stop the process and obtain the answer. Note that if k least significant digits should have sum m (where 0 ≤ m ≤ 9k), we should obtain the answer greedily, going from the right to the left and putting to the position the largest digit we can.


So I need to solve $\begin{pmatrix} 1 &2\\  1 &2 \end{pmatrix}X=\begin{pmatrix} -1 & -5\\  -1 &-5 \end{pmatrix}$. I took $X=\begin{pmatrix} a &b \\   c& d \end{pmatrix}$ and I got that $a+2c=-1$ and $b+2d=-5$. What do I do now or do you have any method to solve this and find values for $a,b,c,d$?  P.S. Determinants are $0$ so you can not use the inverse.


Ubuntu newbie trying to migrate from Windows.  I installed XAMPP, the installer placed the files in /opt/. I am trying to add my own work and after some digging I found that XAMPP serves files from the htdocs folder.   When I try to save a php file from VSCode to that directory it fails due to permissions. How do I get around this? Am I missing something, is this how you use XAMPP? I looked on their websites but couldn't find anything which lead me to believe I must be doing something wrong.  I am applying the same approach I used with WAMP on Windows.  Thanks in advance.  EDIT:  I ended up setting up a symbolic link using the second solution from this . Thanks @pa4080 for pointing it out.


Coloring digits with the listings package

I'm trying to typeset some python code, and I would like integer literals to be highlighted. I've come up, after about two hours of fighting with the documentation and various other questions here and on SO, with the following:  \lstset{ %     language=Python,     otherkeywords={1, 2, 3, 4, 5, 6, 7, 8, 9, 0},     morekeywords=[2]{1, 2, 3, 4, 5, 6, 7, 8, 9, 0},     keywordstyle=[2]{\color{orange}},     keywordstyle=\color{blue}\bfseries,     stringstyle=\color{red}, }   Unfortunately, that doesn't work. Numbers found in strings are also highlighted, which is rather annoying, and not only are they highlighted: they are highlighted in blue. Numerals in regular program text, on the other hand, are rightly highlighted in red.  Help?  EDIT: Thanks Peter Grill for your very nice solution. Is there a way to not break string colouring, though? When I use you code, the stringstyle=\color{red} doesn't seem to work anymore (strings are just plain black). Similarly, comments can be enclosed in triple quotes in python, and if I adapt your quote to detect """ blocks, then the corresponding  comments are not highlighted anymore.


Show that $\lim\limits_{n\to\infty}\frac{a_1+a_2+\dots+a_n}{n^2}$ exists and is independent of the choice of $a$

Suppose $f:\mathbb{R}\to\mathbb{R}$ has period 1, and for some $q\in(0,1)$:  $$|f(x)-f(y)|\leq q|x-y|\quad \forall x,y$$  Let $g(x)=x+f(x)$, for any $a\in\mathbb{R}$,define the following sequence:  $$a_1=a,\quad a_2=g(a_1),\quad a_3=g(a_2),\quad \dots,\quad a_{n+1}=g(a_n)$$  Show that  $$\lim_{n\to\infty}\frac{a_1+a_2+\dots+a_n}{n^2}$$  exists and does not depend on the choice of $a$.  I don't even know what is the possible approach, any hints? Thanks!


What are "Commited Memory", "Cached", "Paged", "Not-paged pool" & How They are Different with "In-Use Memory"

I was thinking to add some RAM to my computer as it goes slow these days, so i came to the Taskbar to see memory usage statistics but i had difficulty  guessing the real meaning of some memory management parameters. so  Q1: What exactly are Commited Memory, Cached, Paged , Not-Paged pool and how they are different with In-Use Memory.  Q2: As far as i know the kernel has a complex memory management algorithm, so if i have some free memory shown in my laptop's RAM can i conclude that my physical memory is sufficient?


Best way to "Save a Copy" of an image in Python?

I have an image (bpy.types.Image). I want to "Save a Copy" of the image, ie. save it to a specified file without modifying the image. I want to be able to specify the format to save as (eg. JPEG, PNG). What's the best way to do this in Python?


Card karte; Stack <Card> kartenstapel;   public Standard52() {       /** this works*/      this.karte = new Card(Suit.HEARTS,13);                              /** this throws a 0-pointer exception when I try to initial*/       this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));      this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));      this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));      this.kartenstapel.addElement(new Card(Suit.HEARTS, 13));  }   Why i get a null pointer exception when i try to inital it.  Its more theorie then practice but i do not undersstand my failure maybe some of you can explain me where my mistake is.


I'm just beginning to learn Python 3 and am having trouble creating a list of strings from a file. Instead, it appears to be making a list of list. Each line of the text file is an element is the list. Each word is an element of a list within the first list.   I've tried google searches for creating lists from files and have read a couple of books on Python. I've also watched Udemy videos.  fname = input('Enter file name: ') try:    fh = open(fname) except:     print('File not found')     quit()  list1 = list() for item in fh:     list1.append(item.rstrip().split())  print(list1)   Actual Result:  [["I'm", 'using', 'this', 'file', 'as', 'an', 'example'], ['of', 'pulling',    'a', 'list', 'of', 'strings', 'from', 'a', 'file'], ['Rather', 'than', 'making',    'each', 'word', 'an', 'element'], ["it's", 'making', 'each', 'line', 'an', 'element']]   Expected Result:  ["I'm", 'using', 'this', 'file', 'as', 'an', 'example','of', 'pulling', 'a',   'list', 'of', 'strings', 'from', 'a', 'file', 'Rather', 'than', 'making', 'each',  'word', 'an', 'element', "it's", 'making', 'each', 'line', 'an', 'element']


I am writing an installation script in PHP, where the user has to enter the username and password of the root MySQL user.   Currently I use:  fgets(STDIN)   to read the username and password, but this is not secure because other people might glance and see the password typed.  Is there a way to input the password from the user, such that it will look like this: "**", similar to how it looks like in a webpage?


Young Adult Science Fiction: Implants, Elite and Slave Classes

A friend described a book he remembered reading as "It was set in a future dystopia ruled by an aristocracy fitted with mental implants. At a certain age, all children got fitted with an implant, and those whose bodies accepted the implants became/remained part of the social elite, and those who rejected it became slaves (shaved heads were important somehow in this whole process - I THINK the slaves all had shaved heads).  The story was written from the point of view of a child of one of the most elite elites, as their social group approached their implant fittings.   In the end of the story, one of the child's close friends becomes a slave, and the child finds out that who will reject their implant, and hence become a slave, is in fact decided in advance and is done to maintain the status quo.  It would have been young-adult SciFi, PROBABLY written before the '80s."  It sounds very familiar but no matter what I search for or try to remember I can't get anywhere. Does anyone recognize this plot?


input autocomplete="off" not working in Chrome latest version

when I click input type text fields the address saved in browser shows. I do't want to show it. autocomplete="off" not working in input fields within the form in chrome Version 75.0.3770.142 (Official Build) (64-bit)


Trying to install xfce4 on Ubuntu server 18.04.1

I've been a long time user of xubuntu and finally bit the bullet and installed the server version as I am running this PC mainly for fileserver and streaming purposes.   That said, I'm trying to install xfce4 as the GUI, but even though every webpage states just use apt-get or just apt install xfce4 am met with the following:     Reading package list... Done   Building dependency tree   Reading state information... Done   E: unable to locate package xfce4     This seems to be the same for any files pertaining to xubuntu. I'm guessing there may be something lacking in my resources list,  But if this is the case....why do so many webpages just advise to install xfce4 and then lightdm??  I'm a stubborn @#£11!! and have no intention to go back to an xubuntu install as it takes an age to remove all the shash I don't want, so would rather get it right first time...


How do you remember(if you really do :-)) all the different levels and what each level does? Can anyone suggest an easy way to remember?


Set fixed sizes for display ad banners to prevent page content moving

The leaderboard banners seem to always have the same size. Setting this with CSS would allow the ads to load later than the page content without having the content move around or scroll position change.


I need some help with dual booting ubuntu 16.04 on windows 10

I'm trying to dual boot my HP notebook 15 and I can't install it from live USB.   I split my C: drive into C: and F:. I want to install Ubuntu on F:. It runs Windows 10 and has InsydeH2o BIOS.


How do you describe these animals' action/ state before attacking their prey?

Some animals like tigers, lions, cats, etc do this action before attacking their prey suddenly and unexpectedly. In fact they seem waiting insidiously (?) until the appropriate moment for attacking and (usually) the poor prey is not aware of their presence.  What is the verb, phrase, or idiom for describing this action/ state?  I have found  but I don't know wether it can be used for animals or not.


Can customs duty be avoided while carrying 3 laptops?

My uncle is travelling to India from the US. He has two office laptops and he's bringing one laptop for me. Is there any way he can avoid custom duty at the airport?


How to Simply Customize \Itemize to Display More Like \Description

Is there a simple way to customize \itemize so that the output indents beginning with the second line similar to that of \descripton? Consider \documentclass[12pt]{article} \usepackage{lipsum}  \begin{document}  \begin{itemize} \item  \lipsum[2] \end{itemize}  \begin{description} \item \lipsum[2] \end{description} \end{document}  which produces the output for \itemize:  and for \description:  Is there a way to embed the indententation feature of \descripion into \itemize (i) on an as-desired basis; (ii) at once for the entire document (if so desired)? Thank you.


The example below was taken from  which helps to identify a closure. for (var i = 0; i < 10; i++) {     (function f() {         var i2 = i;         setTimeout(function g() {             console.log(i2);         }, 1000);     })(); }  The following explanation was given:  For g: List the variables: console is a free variable. i2 is a free variable. Find the parent scope to which each free variable is bound: console is bound to the global scope. i2 is bound to the scope of f. In which scope is the function referenced? The scope of setTimeout. Hence console is not closed over by g. Hence i2 is closed over by g.  However I am not able to understand the bolded part - could you explain it to me?


How do I change the login manager's keyboard layout?

I have a netbook with an AZERTY layout. I've changed it to "bépo" to try it, but now I've reset it to a french layout.  While all the apps have taken the change into account, Ubuntu's login manager still uses bépo, making entering passwords a challenge. I've enabled the virtual keyboard for the time being so that I could login again.  I don't remember what I had done in the first place to switch the login screen to bépo, but now I can't switch it back.    EDIT : In the keyboard settings page, if I click "use system defaults", then everything is in bépo ! Where is this different keyboard layout set ?  ANOTHER EDIT : Here's what did not work :   Changing the layout in settings using the "use system defaults" checkbox in settings sudo dpkg-reconfigure keyboard-configuration changing it in Xconf adding a line in /etc/lightdm/lightdm.conf  sudo dpkg-reconfigure locales slaming head against desk dpkg-reconfigure lightdm sudo gsettings set org.gnome.libgnomekbd.keyboard layouts "['fr']" combinations of the above     Is it possible to relaunch the keyboard configuration tool that's in ubuntu's setup ? The thing has automatic layout detection and it changes the setting everywhere.


I have a simple circuit consisting of 2 ideal voltages sources (each 5V) parallel to a resistor of 5 ohms. The current along the resistor is 1A, right? But by applying the superposition principle (i.e. considering individual sources), I am not getting this result. Am I doing some blunder?


confused about java while loop ,hope anyone can help me .?

this question is about change a variable for while ,but not valid in it . the code like below:  public class StopThreadTest extends Thread { private boolean isStop = false;  private void setStop() {     isStop = true; }  @Override public void run() {     while (!isStop) {         try {             Thread.sleep(1);         } catch (Exception e) {             e.printStackTrace();         }     } }  public static void main(String[] args) throws InterruptedException {     StopThreadTest test = new StopThreadTest();     test.start();     //     Thread.sleep(2000);     test.setStop();     System.out.println(" has set stop ... "); }}   when i run this code ,the program can terminated normally. but when i comment out the code in run method (just like below) ,the program can't terminate itseslf.  @Override public void run() {     while (!isStop) {         try {             //when comment out the blow line ,the program will runs forever .             //Thread.sleep(1);         } catch (Exception e) {             e.printStackTrace();         }     } }   but when i set the variable "isStop" volatile ,the programe again run normal.  private volatile boolean isStop = false;   so, my question is :  a. if not use volatile ,the variable can't read again in while loop ? but why when has an operation (such as print a word,or sleep 1 mills) in while loop,it can work normal ?   and my env is (windows 10,x64, jdk1.8)  hope anyone can help to explain this phenomenon?


I am an American and pay taxes in US dollars. I have some holdings in another currency, for instance, the Euro. Obviously the funds have never been repatriated but this lack of tax event is messing with my accounting.  From my basic understanding, the tax event would be long or short term capital gains solely based on my initial entry into the foreign currency, and then how many dollars I have when I liquidate that foreign currency. Simple enough.  This starts becoming complicated for me when I am also invested in shares of companies denominated in this currency. The trades and investing has been largely successful, but is it such an absolute that there is no US tax event for these foreign denominated trades?  We can ignore PFIC regulations for this question. I am only concerned about income tax, capital gains tax and dividend withholding for the US jurisdiction.  The way I understand it right now, the only tax event is the one that occurs when I liquidate the financial products AND bring the proceeds back to my US accounts, and where new total is more than what I began with (capital gain).   And all of this is compounded by the fluctuations in the exchange rate. I feel like I can't even estimate my taxes if I wanted to. So I can't be the only one that has ever faced this dilemma, I have no need to actually realize capital gains or repatriate, so are there accepted guidelines


Let ($x_s$) be a convergent sequence, where $x_s>0$ for all s, and $y_s$ be a sequence such that   $$\displaystyle \Large y_s=\frac{s}{\frac{1}{x_1}+...+\frac{1}{x_s}}$$  Prove $\displaystyle \lim x_s$=$\lim y_s$  So I know things like $x_s$ is bounded, and that it's Cauchy, but I can't think of anything to solve it.  Any help is appreciated.


is there a way to set coloring for cd tab complete?

I use ubuntu 11.04.  Is there a way to set coloring for output after tab completion listing of a cd, ls, or etc. ?  i.e.   myshell@root$ cd ~/user/files/ I hit tab...  myfile myfoo  mybar <--  this output is colored?  I hope you enjoyed my diagram.


Popular depictions of electromagnetic wave: is there an error?

Here are some depictions of electromagnetic wave, similar to the depictions in other places:      Isn't there an error? It is logical to presume that the electric field should have maximum when magnetic field is at zero and vise versa, so that there is no moment when the both vectors are zero at the same time. Otherwise one comes to a conclusion that the total energy of the system becomes zero, then grows to maximum, then becomes zero again which contradicts the conservation law.


If $\tan\left(\frac{\pi}{4} + \frac{y}{2}\right) = \tan^3\left(\frac{\pi}{4} + \frac{x}{2}\right)$, prove that $\sin(y) = \sin(x)\left[\frac{3+\sin^2(x)}{1 + 3\sin^2(x)}\right]$  I come until the step where  $ \cos{y}=\cos^3{x}$  After this I dont now what to do


If I get a schengen visa issued from greece embassy, and it was the first visa on my passport, can I enter germany without any problem as a first entry?


Can I hook into user registration *before* a user is created?

I want to limit registration based on the domain associated with their email address. I was looking at the user_register action hook, but it fires after the user is already inserted, which, although it could be hacked into working, is less than ideal. I want to preempt rather than retroactively remove invalid users.  I've looked through the source in wp-includes/user.php, but nothing in there looks to be helpful. I did notice the pre_user_email filter, but that doesn't seem to offer any options for doing anything useful since I can't see a way to do anything with that.


Proving that there is some $x$ such that $\gcd(a + bx, c) = 1$

Let $\gcd(a,b) = 1$ and $c>0$. Pove that there is an integer x such that $\gcd(a + bx, c) = 1$. This question is from Section 2.3 (Covers the Chinese Remainder Theorem) Problem 15 of An Introduction to the Theory of Numbers by Niven and Zuckerman. I didn't use the Chinese Remainder Theorem in my attempt, but I suspect that it should, since $\gcd(a,b) = 1$. In fact I didn't even use that $\gcd(a,b)=1$, either. Attempt: Instead of finding $x$, we find what $x$ cannot be. That is, $y$ such that $\gcd(a+by,c) \neq 1$. Reduce $c$ into its prime factors, so that $c = c_{1}^{i_{1}}c_{2}^{i_{2}}c_{3}^{i_{3}}...c_{n}^{i_{n}}$. Then we can solve, for each $1 \leq m \leq n$, $a + by \equiv _{c_{m}}0 \Leftrightarrow by \equiv _{c_{m}} -a$ The point is that if $a + by$ and $c$ have a GCD other than $1$, then one prime factor must be in common. $by \equiv _{c_{m}} -a$ has solutions when $gcd(b,c_{m})$ divides $-a$ and has no solution otherwise. Suppose there are no solutions for all $m$. Then we are done, for there are no restrictions on $x$. Suppose for some or all $m$, there are solutions. Then $by \equiv _{c_{m}} -a$, has solutions $y \equiv _{c_{m}} -(\frac{a}{g})y_{0}+t(\frac{c_{m}}{g})$. Where $g = \gcd(b,c_{m})$, $t = 0,1,..,g - 1$, and $y_{0}$ is a solution to $(\frac{b}{g})y \equiv _{c_{m}}1$. But the set of all these solutions cannot equal $\mathbb{Z}$, because there are infinite primes and finite $c_{m}$. So there must be some integer $x$ such that $gcd(a + bx, c) = 1$. $\blacksquare$ I don't like this proof, because it's nonconstructive. Is there a way to use the CRT or some other basic number theorem?


Access Android log files for specific periods on android 7

Is it possible to access old log files,lets say 3 months old, to see the usage on the android device, by usage i mean, any app installed or unistalled, time spent online, via wifi or cellular, time offline, times switched on and switched off,apps used and any other usage data.  Is this possible through the ADB on windows? I want to be able to connect the tablet to my PC and access all the logs for the last 3 months, currently am just getting the current date only, i cannot even get logs for yesterday. The command am using is adb logcat > currentdevicelog.txt  Any help would be highly appreciated, the version of android on the device is Nougat-7.0


chromium mouse cursor is not changing, how to fix?

So, when hovering over links, or anything else on the chromium window, the mouse cursor will not change, it will remain the last one that changed because of some click event.  How to fix it?  I am on ubuntu linux , I am using latest chromium 53.0.2785.143-0ubuntu0.14.04.1.1145 I have an NVidia GeForce GTS 250


I'm new to both subjects and also this forum, so any help would be greatly appreciated.  Proof by induction if that $G$ is a complete graph with n vertices, then the number of edges of $G$ is $n (n - 1) / 2$.  Thanks in advance.


Question about number of elements in $HK$ if $H$ and $K$ are finite subgroups of some group $G$

Let $H$ and $K$ be the finite subgroups of some universal group $G$. Define $$HK = \{hk \,| \, h \in H, k \in K \}$$ I want to prove that $|HK| = \frac{|H||K|}{|H \cap K|}$, where $|Q|$ is the number of elements in set $Q$. This was my process:  I proved that $H\cap K$ is also a subgroup. Think of $HK$ as a collection of left cosets of $K$ defined by $H$ i.e. $$HK = h_1 K \cup h_2 K \cup \ldots \cup h_{|H|} K $$ The set $HK$ as defined above has $|H||K|$ products. But if an element of $hk$ is repeated, we need to make sure we don't overcount. If $$hk = h'k' \\ hk = (ht)(t^{-1}k) \implies h' = ht, k' = t^{-1} k\\ $$ where $t \in H \cap K$. This tells me that each element of $HK$ has at least $|H\cap K|$ repetitions, each.  The problem I have is, how do I prove that if $t \in H$ but $t \notin K$, the statement $h' = ht, k' = t^{-1}k$ is untrue? Essentially, if $a \in G, b\notin G$, is it always true that $ab \notin G$? The closure property of groups states that if $a,b \in G$, then $ab\in G$. But it makes no mention of $a \in G$ and $b \notin G$. I feel like I am missing something obvious, but I can't place my finger on it...


Is there a way to have c# open another program using events?

For example: if one program had an alert, another separate program pop up when that alarm goes off?


Why didn't James potter make himself the secret keeper?

I don't get why he had to choose one of his friends


In this  there are 11 steps to setup Conky; I did all of them but the terminal show this message:  The program 'conky' can be found in the following packages:          * conky-cli          * conky-std Try: sudo apt-get install <selected package>   I then try this but saw this message:  ismail@ismail-ASUS:~$ sudo apt-get install conky [sudo] password for ismail:  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?   Can you help me?


Determine if rectangle contains or has intersection with path

I have an image and all text is marked by rectangles around each word. I need to select some words by marking them with finger. To do so, I draw a line on the image. I need to check which rectangle contains that line.  how I can check if a rectangle contains that line.    i want get rectangle on which line as drawn  Edit This has been implemented in Google Translator App. I need exact same behavior.


Should I pay for a certificate showing the quality of my manuscript before I submit it to a journal?

Some commercial services sell certificates to manuscript authors.  Frequently these certificates are marketed to authors in developing countries where English is not widely spoken.  These services claim that the certificate indicates that the manuscript meets a certain standard of quality.  Often the certificate states that the manuscript is written in correct English.  The certificate may be accompanied by editing services.  Should I pay for a certificate and send the certificate to a journal?  This is a general question is inspired by  to avoid talking about a specific service.


How did Data's cat "Spot" change colors/breed/gender mid-series?

After seeing a question regarding the acquisition of Data's cat Spot, the point was brought up that Data's  midway through the series.  My question is, how? I have thought up two possibilities (see below to my own answer) but I'm wondering if there aren't possibly others that might fit better. Exhibit A- Spot the Younger  Exhibit B- Spot the Older


Do i have to pay customs on a year old desktop computer while travelling to india from usa

I built a gaming pc in usa and want to take it back to india will i be charged in customs? If yes how much?(the cost of the pc is around 2000 to 2200 usd) also if i bring a monitor (24 inch) how much will be the customs?


EU national traveling to EU home country with non EU spouse

I'm a Portuguese citizen, living and working with my Indian husband in UK. He has a British residence card. He has traveled visa free to other European countries with me. My question is, does he need a visa to travel along with me to Portugal? It's a tourist trip for a week. If yes, is it a free visa?


How do I position a div with a colored background over a preceding image?

Stumped.  I have a basic card with an image and a text tag I want to float over the image.  The tag should have a background color behind the text and above the image.  The background of the text goes behind the image instead.      html

Image Tag

     css  img {   max-width:100%;   height: auto;   margin: auto;   } .card {   max-width: 320px;   margin: auto;   } .card__tag p{   background: blue;   color: lime;   padding: 0.25rem;   margin-top: -3rem; }


How to turn every object on my Artboard into different layers in Illustrator?

I drew a popsicle and I want to animate it in After Effects but first I need to separate each object on my drawing into a new different layer   Is there a way to do that?


Is there a word to describe a person who gets uspet at work when he feels others are not working as hard as him?

I have a guy working for me who is at risk within his job. This is because he has, on a couple of occasions walked off the job he had been given as he felt he was working hard and the Boss running the area wasn't. When approached he often cites Team Leaders being lazy etc, the guy is actually a good worker, but by no means a superstar. The Team Leaders are good workers who, while not working as hard (not carrying out manual tasks), they are in fact doing the job they are employed to do, very well. Is there a term for this type of reaction or person?


using your android phone as a proxy server

I wanted to use my android phone as a proxy server, meaning that I wanted to be able to use the IP on the phone as a proxy, so all request and response are received on the phone and forwarded back to the original requestor. How do I do this?


Automorphisms of a finite non-abelian group

Sia $G$ un gruppo non abeliano di ordine $21$, quanti automorfismi possiede un gruppo siffatto?  Translation (by Davide): Let $G$ be a non-abelian group of order $21$. How many automorphisms does such a group possess?


Let $V$ be a vector space and $U,W$ and $Z$ subspaces of $V$.  Does $V = W \oplus Z$ and $V = U \oplus Z$ necessarily means that $W = U$?  Thanks!


Who are the 3 men who would have a chance against Jaime Lannister in a sword fight?

In Game of Thrones season 2, episode 8, "The Prince of Winterfell" , Jaime Lannister says to Brienne:     There are three men in the kingdoms who might have a chance against me [in a sword fight]   Who are those three people?                                  I don't believe this quote, or any variation, appears in the books. There was this quote from A Storm of Swords when he is fighting Brienne:     She is stronger than I am.      The realization chilled him. Robert had been stronger than him, to be sure. The White Bull Gerold Hightower as well, in his heyday, and Ser Arthur Dayne. Amongst the living, Greatjon Umber was stronger, Strongboar of Crakehall most likely, both Cleganes for a certainty. The Mountain’s strength was like nothing human. It did not matter. With speed and skill, Jaime could beat them all.   So in the books it suggest that Jaime can beat anyone, though he is only referring to people of great strength, not necessarily of great skill (somebody such as Barristan Selmy, who is not considered to be exceptionally strong but is exceptionally skillful, may be able to beat him).  Is there any canon evidence to suggest who these three people may be?  I won't accept any purely speculative answers. However if there is no direct canon quote answering the question (which I believe to be the case) I will consider answers that are strongly inferred from canonical sources (such as a canon quote saying X is the greatest fighter in the kingdom, for example).


Determining the standard error of a ratio of means

I hope that this request will make sense. I am not extremely proficient in these kinds of stats, so please also excuse my limited vocabulary.  I have two datasets, we'll call A and B, and for each dataset I am calculating a statistic that is the ratio of two means, i.e. $\%_A=\bar{x}_A/\bar{y}_A$ and  $\%_B=\bar{x}_B/\bar{y}_B$. What I want to figure out is whether the ratio for dataset A is statistically distinguishable from the ratio for dataset B (that is, looking at the ratios visually, they seem to be different, but can I actually say with any confidence that they are different based on the number of observations I have for each dataset?).  My understanding is that if I calculated the error for each mean, I could simply look to see if the error bars overlap - if they don't overlap then the difference might be real, but if they do overlap then I can't say if the difference is real or not. I would normally determine error by simply calculating standard error iof the mean (STDDEV/SQRT(num_obs) ), but I do not know how, or if, standard error would propogate when taking the ratio of two means this way.  Perhaps I am taking completely the wrong approach. I would appreciate any guidance you can offer.


Converting shapefiles to text (ASCII) files?

How can I convert a shapefile (GIS) to text, or, how can I extract the information in a shapefile?


I have an old laptop,Dell Vostro 1510. I needed to install Kubuntu 14.04.3 on it. It doesn't recognize the wireless. I entered:  lspci -nn | grep 0280  in a terminal, as @chili555 suggested in question 547746 right here in ask ubuntu, and the outcome is:  0c:00.0 Network controller [0280]: Broadcom Corporation BCM4312 802.11b/g LP-PHY [14e4:4315] (rev 01)   Kubuntu 14.04 recognized wireless while live. I know there are some questions exactly about this on www.askubuntu.com but none have reached an end. Thank you


How to remove the paste icon from my desktop

I am using Windows 7 and a Paste image got stuck on my windows screen which is not going away as shown in the image below. Does anyone know how should I remove it? I don't want to restart my computer every time to get rid of it which I have done many times in the recent past. Please let me know any other solution.