How to print selected number of lines in repeated fashion from a long file?

I want to be able print line 1,2,3,4,7 by skipping Lines 5,6,8,9 and repeat the pattern till the end of file.  Sample INPUT:  Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8 Line 9 Line 10 Line 11 Line 12 Line 13 Line 14 Line 15 Line 16 Line 17 Line 18   Desired Output:  Line 1 Line 2 Line 3 Line 4 Line 7 Line 10 Line 11 Line 12 Line 13 Line 16   Using Solaris 10, KSH. Would love an nawk or sed solution


Will reputation spiral out of all control?

Since reputation is relatively 'cheap' to gain, it can be awarded to others 'for free', and can only seldom be lowered, does this mean overall reputation scores will get higher and higher and, effectively, become meaningless?


Question  If $a=\langle12,5\rangle$ and $b=\langle6,8\rangle$, give orthogonal vectors $u_1$ and $u_2$ that $u_1$ lies on a and $u_1+u_2=b$  My steps:  I am not sure whether or not $u_1$ has to lie in the same direction as vector a.  but I know that it has to intersect it  then I recognize that $u_1$ and $u_2$ has to lie perpendicular on vector b,  but I do not know what to do from here  a detailed explanation is much appreciated.


meridian convergence local coordinate systems

I am new to the concept of meridian convergence. I understand that it is the angle between True North and Grid North. But I have problems understanding how   meridian convergence affects local Coordinate Reference System (CRS), such as the Gauss-Krüger system?


Link to league table in Area 51 Discussion Zone leads to 404 error

The "top 10% overall" link goes to this URL:    which is a 404 error.


I upgraded my version of blender to 2.76, and to my horror, quickly discovered it replaces spaces in the file names with underscores. Is there a way I can turn this off?  Even a script would do!


How to remove the superfluous empty line before the list environment?

I want to put the section title in the left margin using titlesec. However, it results to a superfluous empty line when using list environment. How should I remove it without using vspace?  Minimal example:  \documentclass{article}  \usepackage{geometry} \geometry{   a4paper,   top=2cm,   bottom=2cm,   left=4.5cm,   right=1.5cm, }  \usepackage{titlesec} \titleformat{\section}[leftmargin]{\large\scshape\sffamily}{}{0cm}{} \titlespacing{\section}{2.5cm}{2ex}{0.5cm}  \usepackage{enumitem}  \usepackage{mwe}  \begin{document}  \section{Section A}  This line is aligned with the section title.  \blindtext  \section{Section B}  \begin{itemize}[nosep]   \item This line is not aligned with the section title. \end{itemize}  \end{document}


How to correct bad georeference data in a raster?

I'm doing a bit of vegetation mapping and  I'm relatively new to GIS.  My issue is that the aerial photographs I have are georeferenced with world files (.jpgw) but they are ever-so-slightly off. The images are referenced in WGS 84 Pseudo Mercator (EPSG: 3857), and come from qimagery.information.qld.gov.au/. The project is in same CRS as rasters (better to project vectors, right?), and I'm using QGIS.       (Green = NP boundary, Blue = Creeks (Aus. Albers, GDA94 respectively)  I could use the GDAL Georeferencer, but this can subject the image to warping which I'd like to avoid. As far as I can tell they don't need any transformation, just a small shift on the lon/lat. It's probably frowned upon, but I just need to click and drag into position -- if my project/target CRS matches the raster I assume it's safe (especially on a small scale like this).  Could I edit the lon/lat in the world file/georef data?  (This ideal because I could perform in batch)  Or is it something simple like the ellipsoid?  (Currently set to WGS 84 to match raster)


but why would I use them? What is the utility of a hard link?


I am currently rather uneducated on the subject, but I was thinking of a general relativity thought experiment. Say I take a charge from infinity and give it velocity to orbit a planet in a circle. Now from the earth's perspective the charge is accelerating thus it should radiate EM waves. But Einstein says there is no experiment you can perform (locally) to determine if you are in free fall in a gravitational field as opposed to floating in free space. But if what I described was the case then there would be an experiment you could perform; you could check for the emission of a photon. Where is the problem?


How do I use albedo, heightmap and normalmap on a material?

I've been going through a couple of tutorials on applying textures using the node editor, but I can't seem to get it right. I downloaded some 3d images, they include (albedo, heightmap and normalmap) but that's as far as I can go. I don't know how I should apply them. While following a tutorial it seems so easy but now that I'm trying it by myself, things get a bit tricky :p. I've already UV unwraped my mesh, now I just need some sort of guideline. Thanks in advance.


Show that $L_p =\frac{1^p+2^p+3^p+...+(p-1)^p}{p}$ is an integer and generalize the integer for all odd integers p

proof the integer: From Fermat's little theorem, if $\gcd(a,p) = 1$, then we have: $a^p \equiv a \pmod p$. Since $p$ is only divisible by itself and 1, so we have: $1^p+2^p+3^p+...+(p-1)^p \equiv 1+2 + ...+ p-1 \pmod p$  $\equiv p(p-1)/2$. Since p is odd prime, $p -1 = 2k$. So we have:  $p(p-1) = kp\equiv 0 \pmod p$. Therefore $L_p$ is an integer.  The question is how can I generalize the integer $L_p$ for all odd integers $p$. That is, in the expression for $L_p$ replace the exponent $p$ with another non-constant quantity depend on $p$ in a way that $L_p$ remains an integer for all odd integer $p$, and justify the choice of exponent.


Accordingly to the result  $$ (\bar{\psi}\psi)^\dagger = (-1)\bar{\psi}\psi \tag1$$  coming from the fact that fields with and without bar anti-commutes, you can deduce that the QCD mass term  $$ -m\bar{\psi}\psi, \quad m \in \mathbb{R} \tag2$$  is not hermitian, so QCD Lagrangian is not. Nevertheless, it has to be hermitian since we have the scattering matrix to be unitary. What is happening here?


Which one of these sounds correct (American English)? Is there a better way of saying this?    I was not sober enough for you not to notice I'd been drinking. I was not sober enough for you to not notice I'd been drinking.


Remove all .class files from folders in bash

I'm making a bash file to remove all .class files that java generates inside the src folder and it's subfolders. The structure is:  project    src       /utils          utils.class       /game          game.class          gameManager.class   So when I execute the script inside the project folder, it search all .class files and remove them, but it doesn't work.  I just created this script:  find . -path "src/*/*" -name "*.class" -exec rm -f {} \;   How can I fix it?


I'm trying to make a very abstract PDO select function, but for some reason, I'm getting an empty array returned.  function listAllProducts () {     return select('products', '', ''); }   function select( $tableName, $property, $value ){     switch($tableName)     {         case "products":             $tbl = 'products';             break;         case "cart":             $tbl = 'cart';             break;     }     switch($property){         case "id":             $property = 'id';             break;         case "name":             $property = 'name';             break;     }      $db = new PDO('mysql:host=localhost;dbname=ecom;charset=utf8', 'root', 'PASSWORD');     if( strcmp($value, '') != 0 ){ //if $value is not empty         $query = "SELECT * FROM $tbl WHERE $property = :value";         $stmt = $db->prepare($query);         //bind params         $stmt->bindValue(':value', $value);      }     else{         $query = "SELECT * FROM $tbl";         $stmt = $db->prepare($query);     }     //execute     try{         $stmt->execute();         $result = $stmt->fetchAll();         return $result;     }     catch(Exception $e){         return $e;     } }   Is there something simple I'm missing?   EDIT: Thanks for the help, but after adding a switch and removing table and columns from my bound params, I'm still getting an empty result set :(  EDIT 2: I've found a somewhat convoluted solution, added it above, but it looks like it's working for now! More testing is necessary.


Detect is site opened in iframe and redirect

there is a web app. It suppouse to be avilable only in specific iframe (corp. site), so uninvited guests are redirect to clients web site by script.  Code below is working, but java could be disable in browser. IP white list would be a great solution, but too many dynamic IP is used.  What php trick can be used to check is site opened in iframe?  <script>                 if (top === self) window.location.replace('http://uninvited-guests-go.here');  </script> <?php header('X-Frame-Options: ALLOW-FROM https://iframe.allow.only'); ?>


How to receive a POST request in your org?

I need to create lead records when a non-salesforce piece of software sends a POST request with data to my org. How is it done?


Another bad (really bad!) close review audit

When  I was certain it was an audit verifying I would close it as Off topic: asking to recommend a favorite tool, library, offsite resource, whatever.. Turns out to have been the opposite - it was a review audit expecting me to Leave Open which  I failed.  What's the best option for creating a GUI for golang I want to know what my best choice is for creating a GUI desktop application with Go. Is it best to use a browser based ui like webkit?  That's it; that's literally the whole thing, which got 5 upvotes. It seems like a pretty clear case for closure recommending favorite tools & libraries, or even "primarily opinion based" to me. Can this get taken out of the review audits?


If every subspace of V is T-invariant, prove that T is a multiple of the identity map.

Suppose V is a vector space and T is a linear transformation. If every subspace of V is T-invariant, prove that T is a scalar multiple of the identity map.


For an abelian group, is the order of a+b the lowest common multiple of orders a+b

A true or false question, is there a counter example or short proof for this statement? Let G be an abelian group. For all a, b ∈ G the order of a + b is the lowest common multiple of the orders of a and b.


I just started experimenting with Linux, and wsl2 seems like a great option to do so, and still keep Windows 10. I know for sure I can install programs (since I decided to test it with the Minecraft Linux launcher, and got no errors) But how can I display the window inside Windows? So far I have received this error:  Gtk-WARNING **: 15:16:44.531: cannot open display:  I suppose that means that Windows currently "owns" the displays, and Linux would have to make some remote connection, in order to make it work. I've found some instructions online (even on superuser), but I'm currently too big of a Linux noob to make it function.


What documents can I use to return to US if I don't have a passport?

I am an American citizen born in the United States. I am in Mexico at present.  Can I use my birth certificate and drivers license to cross the border by foot if I don't have a passport?


I want to reverse a char array and print the reversed word as an array

I am trying to print the given char array into the reversed char array  I tried but getting the given char array as a reversed string.  public class Test {  public static void main(String[] args) {                char[] letters = {'J','A','V','A'};     int i = letters.length - 1, j = 0;     char[] let = new char[letters.length];     while(i >= 0){          let[j] = letters[i];          i--;          j++;     }     for (char c : let){          System.out.print(c);     } }  }   expected result is if Input: {'J','A','V','A'} then output should be {'A','V','A','J'}  But actual output im getting is "AVAJ"


What should someone from the US know when driving in Italy?

For instance, I know one should not turn on red lights, which is different from US/Mass. rules.   What are other things which can confuse a driver from US while driving in Italy? More generally, are there things a North American driver should know about driving in Europe?


Let be $a, b$ in $(0,1)$ such that $a+b>1$. I need to prove that:  $$2^a+3^b<3a+4b$$  I'm looking for an elementary proof that doesn't resort to the calculus tools.


My STL format export is only 1KB in size? Any idea what went wrong?

I created a simple model and exported the file as an STL. However, when I go to the folder the file is a Certificate Trust List and is only 1KB in size. I don't know what I did wrong.


"A discrete random variable must have a finite range." Is this true? Provide examples where possible

new to the community here and this topic on random variables. This was a discussion question posed to my group, and I have difficulties answering the question. I know that discrete means that its countable, but thats about it.  I saw the question posed called "Properties of a discrete random variable" but it didn't do much help for me.  Many thanks for reading this question.


Cannot update: "No available releases found"

I cannot update some of the modules and the Drupal core itself from "Available Updates" menu. The error is "No available releases found". However, I can list the updates with drush ups.                Why?


A required field that isn't really required?

...the email field in my clients data entry system is required but users of the system are allowed to enter na@na.com if the customer refuses or doesn't have an email address. Is this best practice? Have any suggestions or workarounds for their solution?


What references should be cited to support using 30 as a large enough sample size?

I have read/heard many times that the sample size of at least 30 units is considered as "large sample" (normality assumptions of means usually approximately holds due to the CLT, ...).  Therefore, in my experiments, I usually generate samples of 30 units. Can you please give me some reference which should be cited when using sample size 30?


Windows 8.1 Text Showing Up as Random Artifacts

I had this very random and very debilitating bug occur in Windows 8.1 today and wanted to document it so others can learn how to fix it and maybe someone knows how to prevent it that can provide some advice.  Upon starting my PC, all of my text looked like this picture:   The only thing I know that happened before this is that I tried to install a ttc (Avenir Next Condensed.ttc) font to be used with a Photoshop design file that upon clicking "Install", windows said "this file does not appear to be a valid font". It should be noted that this font was installed on another computer before being transferred to mine (ie it works on another computer, not Windows 8.1, though.)  It also appears this could be a bug related to Visual Studio 2013. (My entire project was missing. - Fortunately, I checked in my code before turning it off... Thank god...)   Shows a solution of copying over fonts from another computer as well as others experience this issue seemingly at random.  To see this bug in action:


Factorization of a number obtained by a modular multiplication operation can reveal factors of the used operands?

Consider a number $r$ obtained by:  $r=a \cdot b \mod n$  Can knowing the factorization of $r$ reveal some information (bits) of $a$ and $b$ ?


If $f(x)=1+2x$ and $g(f(x))=x+3$, what is the value of $g(5)$? Help would be appreciated on how to solve this problem as there has been debate over the right answer ($5$ or $8$).


Trying to save difference between DOB and Current date in years in database C#

i am trying to save years into sql database which I got from subtracting two dates. DOB and Current date. But I get error   Input string was not in a correct format When converting a string to DateTime, parse the string to take the date before putting each variable into the DateTime object   I have tried converting the date to string  * Convert.ToString(txtAge);  Client    function CalculateAge() {                 var dob1 = document.getElementById("<%=txtDOB.ClientID%>");                 var age1 = document.getElementById("<%=txtAge.ClientID%>");                 var dateAry = dob1.value.split("/");                 var birthDay = parseInt(dateAry[0]);                 var birthMonth = parseInt(dateAry[1]);                 var birthYear = parseInt(dateAry[2]);                 var birthDate = new Date(birthYear, birthMonth, birthDay);                 var currentDate = new Date();                  age = currentDate - birthDate;                   mtg = new String(age / 86400000)                   point = mtg.indexOf(".")                           days = mtg.substring(0, point)                      years = days / 365;                  mtg = new String(years);                 point = mtg.indexOf(".");                      years = mtg.substring(0, point);                  age1.value = years.toString();            }


I had submitted a paper to a reputed Computer Science Journal. The reviewer has a lot of constructive changes, in addition to that he also suggested citing a few more papers, all by the same author. Since this is a double blind process, we don't know each other's identity. So, is it common for reviewers to suggest references in this field or any other field ?


My son can’t remember his password on an old Dell that we want to recycle.  I can’t follow the directions provided elsewhere since I don’t have a password and it won’t let me proceed when I type sudo passwd at the terminal prompt with a guest logon.  I don’t need to reformat - just want to clear whatever he had on there before we donate/recycle.  Thanks for your help.


Using an external HD as my applications folder

I need to install more applications - can I use my external HD (samsung T5) and add an additional applications folder? I have loads of space on it and it the speeds are great.


I'm writing my first WordPress theme and have a question about the use of The Loop in page templates. The page templates I've looked at all follow basically the same pattern (example from Twenty Twelve):  <?php while ( have_posts() ) : the_post(); ?> <?php get_template_part( 'content', 'page' ); ?> <?php comments_template( '', true ); ?> <?php endwhile; // end of the loop. ?>   But a page will only have one post associated with it so iterating through the posts seems unnecessary. My page template is more readable and seems to work fine:  <?php the_post(); the_title('<h1>', '</h1>'); the_content(); ?>   Is this a good practice? Are there any downsides?


How to change Figure Label? (Fig.: n instead Figure: n)

This question seems to be asked a lot. I tried some different solutions and any of them did not work.  My figure caption is displayed as  Figure 1: Caption Here   But I want to display:  Fig. 1: Caption Here   I tried the instructions from several questions in the stackExchange website.  Currently my code looks like   \documentclass[12pt, a4paper]{article}  \pagestyle{headings}  \usepackage{tikz} %\addto\captionsenglish{\renewcommand{\figurename}{Fig.}}  \usepackage[font=small,labelfont=bf, figurename=Fig.]{caption}  \renewcommand{\figurename}{Fig.}  \usepackage[english]{babel} \usepackage[latin1]{inputenc} \usepackage{latexsym} \usepackage{amsmath} \usepackage{amsthm} \usepackage{amssymb} \usepackage{verbatim} \usepackage{stmaryrd}  \begin{document} \begin{figure} Drawing here \caption{Caption here} \label{fig:label} \end{figure}  \end{document}   If I uncomment the line \addto... the code does not compile.    I found these references in the following questions:        none of them worked.  I also tried the solution the solution in this other link:  but no success.   I imagine that some of my packages might be in conflict with the caption one. But which one?  Any advice?


I was working on a project while I came across a strange problem. here is my code let newEvent = event; console.log(changes, event, newEvent); newEvent.title = changes.title; newEvent.description = changes.description; console.log(changes, event, newEvent);  The first console.log outputted:  {title: 'Event 2', description: 'blaat'} {title: 'Event 1', description: ''} {title: 'Event 1', description: ''}  and this is what I expected, but what is didn't expect was the next console.log which outputted:  {title: 'Event 2', description: 'blaat'} {title: 'Event 2', description: 'blaat'} {title: 'Event 2', description: 'blaat'}  I expected the following output:  {title: 'Event 2', description: 'blaat'} {title: 'Event 1', description: ''} {title: 'Event 2', description: 'blaat'}  Is there anybody that can help me whit this problem, thanks id advance


Seeking GIS-related magazines and monthly papers

Can you recommend some magazines or other GIS-related papers (printed or digital) which are released on a monthly basis (or every 2-3 months);  I am looking to keep in touch with the GIS fast-growing world and I would prefer something other than books or websites.  Maybe some of you already have a subscription at some magazine.  I am quite interested in Open Source Software but not only.  This post would be the magazine equivalent to another one with useful information about books:


Result: If $X_{1},...,X_{n}$ are iid $f(x;\theta_{0})$, then P[L($\theta_{0}$;$\undertilde{X}$)  > L($\theta;\undertilde{X}$)] Everything shows up fine, but the ">" sign comes out as an upside down "?" if anyone can explain


How do I remove a Windows 7 boot option?

After getting a new SSD I went on and got windows 7 on that one instead of the HDD.  Now during boot up windows asks me to choose between two copies of Windows 7, where one does not work and the other is fully workable. It didn't bother me much except for the fact that I can't leave my computer while it's booting because it will choose the wrong Windows 7.  My question is how do I remove the faulty one? It's quite annoying to wait for this screen to popup before I can leave it alone.


I took out my harddrive (WD 2TB) out of an external casing and put it into an other via usb reading sata docking station which changed something so Windows asks me to format the disk. I got no real experience and knowledge about recovering data from disks unfortunatly and I am not getting any useful information from other persons trys to recover data on other forums and sites.  I got a big truecrypt container on the harddrive which nearly takes all space execpt a little portion where i had a truecrypt.exe laying so i could mount my disk on other systems too. My goal is to restore the disks file system or atleast get this truecrypt container from the disk.  The disk is shown to be "RAW" in the windows Disk Management Tool. This is as narrow as i can describe my problem as my knowdlege allows me to.  I'll post some data about the disk which may be of help for those who understand the information below.


I am wanting advice in securing an email server for large quantities of outbound emails daily.    Would like recommendations on hardware and software, plus cost estimates.   WOuld like system to grow with volume.   Starting out at 30,000 emails per day, and then growing from there.    Want to make sure my business plan can afford this.


prove that $\mathbb{Q}$ can not be $G_{\delta}$ set in $\mathbb{R}$.  let $\mathbb{Q}$ is $G_{\delta}$ set. then $\mathbb{Q}=\cap_{i=1}^{\infty}\  O_i$.  for open sets $O_i$. now each open set in $\mathbb{R}$ is countable union of disjoints  open intervels . then each open set $O_i$ containg $\mathbb{Q}$ must be of the form $\mathbb{R}/P_i,$ where $P_i$  contain countable many irrationals points.  i am not getting this last line that $O_i =\mathbb{R}/P_i,$ with $P_i$  contain countable many irrationals points.  any hint.thanks in advanced.


I'm pretty much every open days in the  with some other regular folks and I just noticed that stars could need a little clean-up and that the  is pretty much absent. Even on SO, ... (not an accusation, right, everyone doesn't need to be an SO addict right? ;) ) I think that the ownership of chatroom should be given to another person if the owner is offline after xx weeks or months. As a room can have many owners, we don't have to remove the ownership from the original one. But, we need some cleanup and small moderation like in the  which is pretty well handled with 5 owners. What do you think?


Question : Show that $\arctan(n)$ is irrational for all $n \in \mathbb{N}$.  Hint:  My solution doesn't use continued fraction.     I am interested in other possible proofs for this question.


How to introduce a line break in a TikZ node label?

I need to introduce line breaks into the label of a node. This is what I've tried so far, but none of it worked:  1:  \node[node, label={[split parts = 4]alpha \nodepart{two} bravo \nodepart{three} charlie nodepart{four} delta }, below of = 5] (8) {$8$};   2:  \node[node, label={alpha\\bravo\\charlie\\delta}] below of = 5] (8) {$8$};   3:  \node[node, label={alpha \newline bravo \newline charlie \newline delta}] below of = 5] (8) {$8$};   All of those approaches are fairly similar. I found solutions on line breaks inside nodes, and on labels on edges, but not in labels of nodes.  In fact, I've tried the suggestions I found on labels of nodes, but it didn't work as well.


Reply icon is not showing for comment in Android app

As mentioned in , when tapping a comment in the Android app, we should have a reply icon, letting us reply to the comment, instead of the auto complete on the site:        However, when I tap a comment I get the "flag" icon instead of reply icon:        What is going on? Can this please be fixed?


When I was a relative newcomer to Yorkshire, in the North of England, I was slightly annoyed when I heard people talking about 'bibs and bobs' (meaning odds and ends). I wanted to correct them by saying it should be 'bits and bobs' but I realised that this had become a dialect issue. I'm wondering if 'bibs and bobs' is in common use in other parts of the UK. (By the way, I know I'm an established Yorkshireman now because I've recently named my new cat Bibs and Bobs.)


The function $f(x)=4^x+6^x-9^x$ is such that $f(0)=1>0, f(1)=1>0, f(2)=-29$ and next $g(x)=(4/9)^x+(6/9)^x-1 \implies f'(x)<0$ for all real values of $x$. So $g(x)$ being monotonic the equation $$4^x+6^x=9^x$$ has exactly one real solution. The question is whether this real root can be found analytically by hand.


Does the Association Bonus count towards the Mortarboard badge?

Recently I passed 200 reputation and got the 100 point Association Bonus.  For the week, it says I only earned 105 reputation, then it says under my profile that I earned 210. Does the association not help? Do I quality for the Mortarboard badge?


Let $p$ a prime number  and let $\mathbf{F}_p(X)$ the field of rational functions over $\mathbf{F}_p$.   The degree $[\mathbf{F}_p(X):\mathbf{F}_p(X^p)]$ is $p$?  I'm a little confused; thanks.


Exception in thread "main" java.lang.NullPointerException at revArr.main(revArr.java:6) in InelliJ IDE

I'm getting the following error while running the program in IntelliJ IDE. It's a simple program which takes input from cmd and prints it. When i run it through cmd it works fine but dosen't work on intelliJ     Exception in thread "main" java.lang.NullPointerException at   revArr.main(revArr.java:6)   public class revArr {     public static void main(String[] args)     {         // Using Console to input data from user         String name = System.console().readLine();          System.out.println(name);     } }


Something is a little bit unclear to me. In the image below you see that you need to divide the angle by a half.  Acccording to wikipedia they say that this is so that I could rotate clockwise or counter clockwise. The sine function returns a value between 1 and -1. So I don't understand it. Could somebody explain why I need to divide my angle by a half?


Can I apply for a US visa in Myanmar as an Indian citizen?

I am a Indian passport holder. I am in Myanmar (Burma). Can I get a visa for the USA from here?


Show that $S_n=0$ for infinitely many $n$

Let the series $\sum_{n=1}^{\infty}a_n$ is convergent but not absolutely convergent and $\sum_{n=0}^{\infty}a_n=0$. Denote by $S_k$ the partial sums, Then prove that $S_k=0$ for infinitely many $k$.  My Efforts  Using the definition that a series converges if and only sequence of partial sum converges.   Now it is given that $\sum_{n=0}^{\infty}a_n=0$, it follows that sequence of partial sum converges to $0$.  Now we can only conclude that around each neighborhood of $0$ however small there exist a stage after which we have infinitely many $S_k$ belong to the neighborhood but that does not prove that $S_k=0$  I request for some helpful comments so that I can solve this problem.


Can a Wizard "reverse-engineer" a magic item to copy the spell into his spellbook?

Is it possible for a wizard to research the magical spell within an item, thus learning how it's composed and legally copy it into his/her spellbook? After some discussion with people who have come with answers stating that it's not possible to learn spells from item which doesn't contain a written spell (like a scroll or a book /tome). I then wonder why it shouldn't be possible for the wizard to research the spell embedded into the magic item, trace the process backwards or just keep using the spell to gain an understanding of how it works and the magics that lies within.  ... For a real-world example, it's the difference between finding a recipe, and finding a cake. You can study the cake all you like, but you probably won't be able to bake one exactly like it unless you find the recipe somewhere. ... //anaximander  This guy definitely has a point, but then again, if you can taste the cake you can figure out what basic components are needed in it, especially if you were a pastry chef or something alike. Shouldn't that go for wizards as well? The reason I'm not satisfied with the given answers is because so far there hasn't been a specific rule stating that it's not possible, just hinting towards and suggesting. Now if we take the cake example and apply it to the wand, we try to backtrack the process of embedding a spell into a wand. How is that done? Is the spell written inside the wand and thus readable with some kind of divination magic maybe? Is there actually a good rule that helps my case (I want it to be possible, but if I get a solid proof that directly states it's impossible I'm accepting defeat) or is it just up to the DM to make a final decision? Summary: Can a wizard learn Magic Missile from the item Wand of Magic Missile? If yes/no, why/why not?  After having asked on the official  page, I've gotten the answer that it's not possible for a Wizard to learn a spell from a magic item the way I've described it. Here's the direct quotes from the person(s) I was in contact with.  The rules on page 114 of the Player's Handbook are pretty specific as far as to what you can use to copy down a spell. Generally, the rules do not support learning spells from magic items that perform similar roles. You are, however, more than welcome to work with your Dungeon Master on a house rule for this if you feel like it should function differently! The rules do only support written sources, as you indicated from that section. Something like a spellbook or a scroll would be able to provide the verbal incantations necessary for a spell, while an item may not necessarily do that. These are the means that are explicitly provided by the rules. Again, you are more than welcome to coordinate with your DM about a house rule!  We see that the major reason why my theory fell apart (sadly) was due to the wand not being able to provide the "verbal incantations necessary". So we can now all rest as the issue has fully resolved. The previous question can be found here:


Make the error "This edit would have to be a suggested edit" more verbose

From  post I found that the error "This edit would have to be a suggested edit" occurs because there has already been an edit suggested for the same post, but the error message is still confusing. Can the error "This edit would have to be a suggested edit" be made more verbose?


Try to add more property to Jquery for .css()

I have this line of code that helps me to add a parallax effect to an arrow. but i want to rotate it in the same time and I tried to add another property of "transform" but it does not work, maybe something is typed wrong. Can someone help me?  So, the line that works is this:  $("#arroww").css("transform",'translate(0px, -'+Scroleaza/3+'%)');   And I tried to use this but still, only the parallax effect is working. If I put the rotate property first, it works and the parallax effect stops working and vice-versa.  $("#dirty").css( "transform",'translate(0px, -'+Scroleaza/3+'%)',"transform",'rotate(50deg)');


Why is .rar file being downloaded instead of .iso while downloading Ubuntu 18.04?

I am trying to download Ubuntu 18.04.3 LTS. I observed that I am downloading a .rar file instead of an .iso file. The official tutorial  assumes that the file is an iso.   I am an amateur. This had happened when I tried to install Kali for fun. So I copied the contents of the folder of the download into my pen drive and booted from it. I am now greeted with a GRUB command line instead of the expected live environment.  Is it expected to download a rar file? If so, am I doing the right thing?  Edit:    Apparently Windows is telling me it's a rar archive even though the extension is .iso.


How can I get the source directory of a Bash script from within the script itself?

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


sudo error: " No valid sudoers uid 601, should be 0 " OSX Catalina

Running OSX Catalina on a 2012 Macbook Pro, I recently edited the etc/hosts file and after I did I started having this problem in during my next startup, I somehow lost all use of sudo, anytime I try and use sudo I get the same error message:  sudo: /etc/sudoers is owned by uid 601, should be 0 sudo: no valid sudoers sources found, quitting sudo: unable to initialize policy plugin  Even when I change the etc/hosts file back it doesn't help so I'm not sure what or why this  triggered the issue. Any advice on how to fix this? Is this bound to happen anytime I edit the /etc/hosts file?


Checking from method for what method called it

Say, I have some Java code  public static void method1(){ ...//method body method2(); } public static void method2(){ ...//method body }   I want method2 to be able to know, as a String, what method called it. For example, in this case, if method1 were run, calling method2, method2  could print out that it was called from method1.  Thanks in advance!


Well, here is the situation. I have four students. They did a test. Suppose that the regulation is a student getting a score below 40 gets the remark "study hard" which is written at the bottom of the work instead of a numerical score. When I want to confirm this, may I say:  They get study hard if their SCORE IS (instead of SCORES ARE) below 40, right?


When did Obito awaken the Eternal Mangekyou Sharingan?

Spoilers if you didn't see episode 473 of the anime yet:      In anime episode 473, Kakashi uses Obito's eyes to create Susanoo. But Obito's eyes were not Eternal Mangekyou. Previously, he had Rinnegan which he has borrowed in addition to one of his own eyes, and that's why he could do lots of stuff.    Note: this is not the same question as the closure says! Eternal Mangekyou is when someone from Uchiha gives his Mangekyou to to someone dear then it becomes eternal and the powers will be activated.


I cannot hit this node application from the browser 52.138.7.79 refused to connect. but i can load up nginx on 80 fine. also i can hit it on the machine using curl. This is running on a Azure Vm and the port is open, the rhel firewall is disabled ... any help is appreciated.


Why don't we treat rubbish the same as spam?

Spam gets fairly heavily punished - 100 reputation penalty, if I recall correctly, and the content itself gets hidden in the revision history.  Now if we just have some rubbish:     dfajiojaifojadiofjadhigaowkokaomdiovnuiyhioqejgioqejgio   I'm not talking about someone posting a question or comment as an answer (i.e. possibly just not knowing the rules or being frustrated with not having the required privileges), or someone making some really horrible attempt at answering the question, I'm talking about an answer that clearly shows absolutely no observation of any content on the page.  This, in my opinion, causes a similar amount of harm to the site - I'm inclined to say the fact that someone posts spam isn't as important as the fact that they're posting something that needs to be deleted, since we're likely going to delete it pretty quickly, and they're (likely) behaving maliciously, or am I wrong?  Why don't we treat this equally harshly, or why do we treat spam as harshly as we do?    Side notes:  I'm sure I've seen a few times where users get punished for posting spam when their link is likely actually relevant to the question and useful (should I flag these? They are still link-only answers, so they shouldn't really come back, and often I'm just not sure enough). While false positives are bad, it seems worse that we're treating worse behaviour better.  I'm assuming that's not what "abusive" in this reason is referring to: (I'm also not sure, off the top of my head, how this one gets treated)     It is offensive, abusive, or hate speech


How to find chromatic number of the $n$-dimensional hypercube $Q_n$?

How to find chromatic number the $n$-dimensional hypercube $Q_n$?  I know $\chi(Q_2)$=2 , $\chi(Q_3)$=2 , $\chi(Q_4)$=4


how can the slopes be calculated using a covariance matrix?

I am very new to the concept of regression. While going through an R output for a multiple regression I came across a set of estimates for the slope and got interested to solve for the same. for 2 independent variables the formula derived from  the covariance matrix works fine but the trouble starts while solving it for more than 2 variables. Can some one help me with how the formula is extended in case of more than 2 IVs? Sorry for this naive question.But I am very curious about the fact. The formula that I have been following is- β1=Cov(y,x1)var(x2)−Cov(y,x2)Cov(x1,x2)/var(x1)var(x2)−Cov(x1,x2)2  For three IVs, does the following formula make any sense? β1=Cov(y,x1)var(x2)var(x3)−Cov(y,x2)Cov(y,x3)Cov(x1,x2)Cov(x1,x3)cov(x2,x3)/var(x1)var(x2)var(x3)−{Cov(x1,x2)Cov(x2,x3)Cov(x1,x3)}2  It will be of huge relief if someone could correct me. Thank YOU.


I got a problem while making a model of a product. I have tried a lot even seen lots of tutorial but did not get the thing that i want. I am using Blender 9.92 and I am just a beginner I got my hands on Blender 7-8 days ago. I've just basic knowledge about I am trying to model a product "Mattress Topper"   This is the exact look of the product, Help me how i can model this product and render realistic images.


How to install wunderlist on Ubuntu 14.04 LTS?

I cannot install wunderlist from the Software Center. Can anyone help me out? Thanks!


I have a dedicated server with 2 TB storage.   My problem is that the whole storage is allotted to the root partition.   Whenever I try to resize it using lvresize, the root partition gets corrupted and then I have to reprovision the server.   Is there any option to resize the root partition without unmounting in lvm?  I am trying to reduce the root partition to 100GB.  Vgs  root@s93079:/home/customer# vgs   VG        #PV #LV #SN Attr   VSize VFree   s93079-vg   1   2   0 wz--n- 1.82t    0   Lvs  LV     VG        Attr       LSize  Pool Origin Data%  Meta %  Move Log Cpy%Sync Convert   root   s93079-vg -wi-ao----  1.79t    swap_1 s93079-vg -wi-ao---- 32.00g   Fdisk - l  Device     Boot  Start        End    Sectors  Size Id Type /dev/sda1  *      2048     499711     497664  243M 83 Linux /dev/sda2       501758 3907028991 3906527234  1.8T  5 Extend /dev/sda5       501760 3907028991 3906527232  1.8T 8e Linux  Disk /dev/mapper/s93079--vg-root: 1.8 TiB, 1965782204416 byt es, 3839418368 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mapper/s93079--vg-swap_1: 32 GiB, 34355544064 byte s, 67100672 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes   Vgdisplay   --- Volume group ---   VG Name               s93079-vg   System ID   Format                lvm2   Metadata Areas        1   Metadata Sequence No  3   VG Access             read/write   VG Status             resizable   MAX LV                0   Cur LV                2   Open LV               2   Max PV                0   Cur PV                1   Act PV                1   VG Size               1.82 TiB   PE Size               4.00 MiB   Total PE              476870   Alloc PE / Size       476870 / 1.82 TiB   Free  PE / Size       0 / 0   VG UUID               dPrEwA-77pM-pGai-9jZB-ldMZ-iL20-HAe9 Dj   lvdisplay /dev/s93079-vg/root   --- Logical volume ---   LV Path                /dev/s93079-vg/root   LV Name                root   VG Name                s93079-vg   LV UUID                bpGNau-XirV-P7PA-8d6k-OCOy-TAwN-HXl FVI   LV Write Access        read/write   LV Creation host, time s93079, 2016-08-27 09:22:05 -0500   LV Status              available   # open                 1   LV Size                1.79 TiB   Current LE             468679   Segments               1   Allocation             inherit   Read ahead sectors     auto   - currently set to     256   Block device           254:0   Lvdisplay /dev/s93079-vg/swap_1  --- Logical volume ---  LV Path                /dev/s93079-vg/swap_1  LV Name                swap_1  VG Name                s93079-vg  LV UUID                j74PLZ-E9gK-9Bbb-EkKq-xRJv-TuU4-FgH gm  LV Write Access        read/write  LV Creation host, time s93079, 2016-08-27 09:22:05 -0500  LV Status              available  # open                 2  LV Size                32.00 GiB  Current LE             8191  Segments               1  Allocation             inherit  Read ahead sectors     auto  - currently set to     256  Block device           254:1   Df - h  /dev/dm-0       1.8T  923M  1.7T   1% / udev             10M     0   10M   0% /dev tmpfs           3.2G  8.5M  3.2G   1% /run tmpfs           7.9G     0  7.9G   0% /dev/shm tmpfs           5.0M     0  5.0M   0% /run/lock tmpfs           7.9G     0  7.9G   0% /sys/fs/cgroup /dev/sda1       236M   33M  191M  15% /boot


Ternary String - finding recurrence relation

A. Find a recurrence relation for the number of ternary strings of length n that contain two consecutive 2s.  B. Use this recurrence relation to compute the number of ternary strings of length 5 that contains two consecutive 2s(not 0s or 1s).  How do I go about and solve this problem step by step as I don't have any idea on how to start it.


How to change the ID in pure CSS JS ?Why My code is not working?

This code is not working, although it seems correct to me. Can you please tell me what's the issue?
hii


I would like to be able to track exports of reports including the filters of the reports. Do you know of any way that this is possible outside of manual recording?


My Samsung netbook (Model Number : Samsung NP-NC108-PO1BD) has 2GB RAM and a 1.6GHz Intel Atom dual core processor.   I installed Ubuntu 14.04 (32-bit version). After the successful installation it is having problems like slow performance, crashing after boot, etc.   I would like to know which distro would be perfect for me. More specifically I have to use it for doing assignments (editing Word, Excel, PowerPoint, pdf making/editing, pdf to doc conversion, etc.). In addition, a little bit of multimedia purposes like web surfing, YouTube and so on. Finally, I am extremely bored with Microsoft and want to switch to Linux completely.  What should I do now? I certainly do not want to go back to Windows.


Why would I not rollover my 401k into an IRA when permitted?

Currently in the US there are circumstances which allow you to rollover your existing 401K into an IRA, such as when you change employers. You may also keep it in the existing employer's plan or roll it into your new employer's plan.  Assuming there is no issue of minimum balances for the funds of interest, why would I not choose to rollover my 401K into my IRA whenever I'm allowed to do so?  It seems to me that an IRA is a superior account type.


Sirius himself says at some point in Goblet of Fire that Crouch pushed through legislation to have him convicted and thrown in Azkaban without a trial.  There seems to be a general consensus, specifically voiced by Fudge but also implicit in Crouch pushing through this legislation, that Sirius was considered one of Voldemort’s innermost, most dangerous, and most trusted right hands. Easily as inner-circle as the Lestranges, for example.  It seems quite unlikely to me that someone so close to Voldemort should not be a Death Eater—apart from Fenrir Greyback (who I would think is much less inner-circle), I do not recall hearing of any of Voldemort’s important servants not being Death Eaters.  As far as canon describes, all Death Eaters have the Dark Mark magic-tattooed on their arm, to be used as a way for Voldemort to summon them to him. Considering that Karkaroff, who had definitely burnt all his Death Eater bridges, still had the Dark Mark, I am assuming that getting rid of the Mark is not possible: once it’s on, it stays on.  Yet, as Hermione points out in Order of the Phoenix (ch. 16, “In the Hog’s Head”), Sirius does not have the Dark Mark.  So why was he so swiftly convicted and locked up? I mean, I know they were eager to be seen to be doing something (as Fudge keeps pointing out is his excuse for most of the miscarriages of justice he commits)… but seriously, did no one think to check if Sirius actually had a Dark Mark on his arm or not? Did the Ministry of Magic not even know at the time that all Death Eaters had the Mark? Or were they just happy to accept—without the scrutiny of a full trial—that a non-Death Eater would commit mass murder for a Voldemort who was presumed defeated?


How to make Generic parameter T Nullable in C#?

I'm creating a generic method which should be able to return null.  As an example I've created this method GetSecondSmallest(List<T>) below. This function loops through all of the IComparable items and returns the second smallest item if possible. If this item does not exist it returns null.  public T? GetSecondSmallest<T>(List<T> items) where T : Nullable, IComparable {     if (items.Count == 0) return null;      T smallest = items[0];     T? secondSmallest = null;      // Find second smallest by looping through list      return secondSmallest; }   Two example usages of this method would be:  GetSecondSmallest(new List<int> {4, 2, 3, 1, 6, 8}) // Should return 2 GetSecondSmallest(new List<MyComparable> {new MyComparable('x')}) // Should return null   When you try to compile this code you'll see what the problem is here:     Error   CS0717 'Nullable': static classes cannot be used as constraints   How can I make this method return either an instance of T or null?    EDIT: I have already seen , but this does not answer my question, because in my situation the parameter is also generic, and should be Nullable. So the provided answers there aren't applicable.


Unable to understand negative string slicing in python

Example code: name = "i am a student" print(name[::-1])  Output: tneduts a ma i


I would like to format some Python code using lstlistings and have function and class definitions in bold, i.e. anything that follows the word class or def. I don't want to individually define the keywords however, as when the functions are called they shouldn't be bold.  MWE:  \documentclass{article} \usepackage[T1]{fontenc} \usepackage[lighttt]{lmodern} % bold and italic ttfamily \usepackage{color} \usepackage{listings} \usepackage{setspace}  \definecolor{Code}{rgb}{0.1,0.1,0.1} \definecolor{Decorators}{rgb}{0.7,0,0.7} \definecolor{Numbers}{rgb}{0.5,0,0} \definecolor{MatchingBrackets}{rgb}{0.25,0.5,0.5} \definecolor{Keywords}{rgb}{0,0,1} \definecolor{self}{rgb}{.87,.46,0} \definecolor{Strings}{rgb}{0,0.66,0} \definecolor{Comments}{rgb}{0.388,0.4705,0.518} \definecolor{Backquotes}{rgb}{0,0,0} \definecolor{Classname}{rgb}{0,0,0} \definecolor{FunctionName}{rgb}{0,0,0} \definecolor{Operators}{rgb}{0,0,0} \definecolor{Background}{rgb}{0.99,0.99,0.99}  \lstset{ language=Python, numbers=left, numberstyle=\footnotesize, numbersep=1em, xleftmargin=3em, linewidth=23cm, framextopmargin=1em, framexbottommargin=1em, showspaces=false, showtabs=false, showstringspaces=false, frame=l, tabsize=4, % Basic basicstyle=\ttfamily\small, backgroundcolor=\color{Background}, % Comments commentstyle=\color{Comments}\slshape, % Strings stringstyle=\color{Strings}, morecomment=[s][\color{Strings}]{"""}{"""}, morecomment=[s][\color{Strings}]{'''}{'''}, % keywords keywordstyle={\color{Keywords}\bfseries}, % additional keywords keywordstyle={[2]\color{Decorators}}, emph={self}, emphstyle={\color{self}\slshape}, }%      \begin{document} \lstset{language=Python, breaklines=true} \begin{lstlisting}     class MyClass:         def __init__(self):             print('do a thing')      foo = MyClass() \end{lstlisting}  \end{document}   This produces     I would like the first instance of MyClass (following keyword class) and __init__ (following def) to be bold, but the second instance of MyClass should be as shown. How would I go about doing that?  Note that only the word between the keyword and the : or the ( should be bold.  EDIT: I've tried adding  \lstset{moredelim=[s][\bfseries]{class }{:},     moredelim=[s][\bfseries]{def }{(},}   with no luck


Replace auto-inserted markdown duplicate banners with real duplicate banners

Long, long ago, duplicate banners used to be mere markdown in the body of a post. Like, for example,   > **Possible Duplicate:**   > [particle で　versus particle　と](https://japanese.stackexchange.com/questions/8107/particle-%e3%81%a7%e3%80%80versus-particle%e3%80%80%e3%81%a8)    <!-- End of automatically inserted text -->   Nowadays, of course, duplicate banners are some separate thing - not part of the body of a post.   Would it be possible to convert markdown duplicate banners into real duplicate banners, either as part of some behind-the-scenes batch job, or as part of some magic that happens when one edits a duplicate post that has a markdown banner?  This would also fix this issue, I guess: .   (Why am I editing duplicate posts that are so old that they predate the current banner system? In this case, to force markdown to be re-baked following this change to the markdown parser: . Unlike questions closed for other reasons, I think duplicates ought to be maintained - users may still come across them and find them useful for whatever reason.)


Why multiplicative group $\mathbb{Z}_n^*$ is not cyclic for $n = 2^k$ and $k \ge 3$

Let G be the multiplicative group $\mathbb{Z}_n^*$ for $n = 2^k$ and $k \ge 3$.  Can we prove that no element has order bigger than $2^{k-2}$ ?  My solution (not really a solution) :  Since $n=2^k$, I thought that this group is cyclic and the generator is 2. I'm not sure if the group order can't be bigger than $2^{k-2}$?


Javascript date function for monthly subscription

I'm trying to calculate dates for monthly subscriptions. I've seen many  to use some variance of: const oneMonthFromNow = new Date(new Date().setMonth(new Date().getMonth()+1));  But when I test this for edge cases it doesn't work as expected, some examples:  Today: 31st march => Expected: 30th of April => Output: 1st of may (since 31 doesn't exist...?) Today: 30th January => Expected: 28th of February => Output: 2nd of March (what about leap years??)  Any ideas on how I can make this work without adding exception rules?


finding value of $\lim_{n\rightarrow \infty}\sqrt[n]{\frac{(27)^n(n!)^3}{(3n)!}}$

Finding value of $\lim_{n\rightarrow \infty}\sqrt[n]{\frac{(27)^n(n!)^3}{(3n)!}}$  what i try  $\displaystyle l=\lim_{n\rightarrow \infty}\bigg(\frac{(27)^n(n!)^3}{(3n)!}\bigg)^{\frac{1}{n}}$  $\displaystyle \ln(l)=\lim_{n\rightarrow \infty}\frac{1}{n}\bigg[n\ln(27)+3\ln(n!)-\ln((3n)!)\bigg]$  How do i solve it help me please


Running find . -name index.html | xargs vi  instead of, say, find . -name index.html -exec vi {} +, seems to do what I want, but with some odd side-effects: backspace prints the delete character ^?, and my Terminal prints text strangely after closing Vim. There are a  of  about find | xargs in general, but my understanding is that xargs without arguments yields space-separated filenames (vi file1 file2 ....), which ordinarily works fine with Vim. What's going on here? Using macOS Big Sur + iTerm2 if it's relevant.


How old did the Istari look when they arrived?

While bound to their mortal bodies, the Istari, though Maia, are susceptible to the same flaws and weaknesses that they are otherwise not - hunger, fatigue, even the temptation of the Ring. Ageing is not an exception. So, if the Istari do age, if ever so slowly, then how old did they look when they arrived, two thousand years before the War of the Ring, relative to an ordinary Man?


Why 'try/finally' interacts strangely with 'return' in Python?

Can someone please explain me why does this work like it does? Python 3.6.3  In [1]: def test():    ...:     try:    ...:         return 1    ...:     finally:    ...:         return 2    ...:       In [2]: test() Out[2]: 2   EDIT: This is not exactly duplicate as linked questions raise exceptions in their try : and my example uses return which I expected to work. This function looks like it should return 1 yet it returns 2 - so basically return 1 is ignored. finally makes a good job of eating any risen exceptions but should it also eat returns?


Gimp installation failed due to depedency

I want to install gimp in 13.10. I follow these procedure to install gimp.  sudo add-apt-repository ppa:otto-kesselgulasch/gimp-edge sudo apt-get update sudo apt-get install gimp   But after i update the system, when i go for the last command.(sudo apt-get install gimp) It show this error  The following packages have unmet dependencies:  gimp : Depends: libgimp2.0 (>= 2.9.1.119-build~33915~145295a~saucy0~ppa) but it is not going to be installed         Depends: libgimp2.0 (<= 2.9.1.119-z) but it is not going to be installed         Depends: libgegl-0.3-0 but it is not going to be installed E: Unable to correct problems, you have held broken packages.   How can i install the gimp and resolve the error. please help me.


Reconstruct the data using first principal component

I would like to know how do I reconstruct the data using only the first principal component of the PCA?


Anomaly in accessing global variables inside a function in Python 2/3

Global variables cannot be accessed within a function without using the global keyword; (fine) but I did not expect the following:  Case 1:  a = 1  def f():   a += 1   print(a)  >>> f() ... UnboundLocalError: local variable 'a' referenced before assignment   Reason I presume: Function could not find variable a in its local scope.  Case 2:  a = 1  def f():   print(a)  >>> f() 1   But now, the function finds variable a in its local scope. Contradicts, the reason I presumed in the previous case.  Why is this happening?


I add this plane, and when I move it, the donut and plane move together.


I am in QGIS. I have a raster layer of mountains and a lake. I have a vector layer (shapefile) of the lake. It sits nicely where it supposed to be over the raster level. I am going to convert this height map to an STL so that I can cnc this out of wood, so I'd like the actual lake to be something like 200 feet lower than it shows on the raster layer so that I can fill it with blue epoxy. I have read a lot of clipping and everything else, and I am lost.


Rename field in SHP file (DBF) with ArcCatalog

I want to rename some fileds on a SHP file, (the fields on the DBF file), using ArcCatalog (ArcGIS Desktop v10.2.2).  From ArcCatalog, right click on a SHP file -> Properties... -> Fields. Then the program let you rename the field and change the data type... apparently.    When I hit Enter or click Apply, an error appears: Failed to alter the name of the field.  The file is not in use, nor read only, and the name of the field is under the 10 character limit.  Ironically, I can do it with gvSIG!


How can I really disable the Cmd to Win key mapping in Parallels Desktop 5?

Removed it from System Preferences > Keyboard. No go. Remapped ⌘ Cmd to be Ctrl. No go. Ripping out the ⌘ Cmd key shouldn't be the solution. Anyone?...


Will it be possible to create apps/games in Java SE or Java ME on new Ubuntu phones?


Can I start such a contact with one researcher that does not know me in one online conference?

I have a major in Mathematics and a masters in Physics and am currently starting my PhD in Physics. Since I've started my masters I am very interested in one particular research field. The main developments in this field have been carried out by a group lead by a very respected researcher. Moreover the book he wrote about the subject together with the papers of his group are what made me be interested in the field. For my PhD I wanted to work with this field. My supervisor works in related stuff and he spent one year in the US doing his own research, but in a group that was actively discussing the subject I'm interested in, so that he got interested as well. In that case he accepted to supervise me. We are right now deciding on what to take as a concrete objective. In that sense I had one particular idea that my supervisor really enjoyed and said it could really be the way to go. We are discussing now the particular details. Now, I'm participating on one online conference and that physicist who leads the group which is making the most significant contributions to the field is participating. Moreover people say that he is approachable and there is one particular moment every day in the conference on which people are encouraged to talk to one another. In that setting, I have been considering starting an interaction with that professor and ask him his view on the general idea of my proposal. In fact, in one of his papers there is one very short footnote briefly saying that one could perhaps do something related to what I have in mind, but his group followed a distinct direction. Now while I think that trying to talk to him could be beneficial I fear whether or not I can do it and how to approach it in this online environment. For starters he doesn't know me and we don't have any common acquaintances. Isn't it a bit of too much asking him privately in one online conference an opinion about an idea I had for my PhD project? In that sense my question here is: can I try starting such an interaction? And if so how is the correct way to approach it given that he doesn't know me?


Unstable projection in LDA space in $n<p$ situation

I'm trying to classify (LDA) few samples (n=12) in a high dimensional feature space (p=24) into 3 classes.  First I reduced the dimension of my initial dataset with a PCA, keeping only the first two Eigen vectors. Update: turns out, I was actually using all 11 PCs for the LDA. Then I had a look at the projection of my n x 2 n x 11 dataset in the LDA space (1st vs 2nd Eigen vector) and I obtained the following:   I was quite happy because the LDA found a strong separation between the 3 classes.  So I tried a leave-one-out cross validation to evaluate the LDA. I trained the classifier with 11 samples and tested it with the last one, and looped around.  The problem is the classifier performs at chance level (30% success rate).  I noticed that the LDA space changes drastically between each iteration, depending on the 11 samples used to compute it. Moreover, when I project the tested sample in the corresponding LDA space, it falls quite far away from what should be its group, explaining the poor success rate.   My questions are: is it normal that such a (visually) nice separation between classes leads to such a poor classification? Is it due to the small number of samples? Is there anything I can do to improve the situation?


Finding the $\mathbb{Q}$-automorphisms of the splitting field of $x^p-2$ over $\mathbb{Q}$.

I have this:  The splitting field of $x^p-2$ over $\mathbb{Q}$ is $\mathbb{Q}(\sqrt[p]{2},\xi)$ with $\xi=e^{{2\pi i}/p}$. $[\mathbb{Q}(\sqrt[p]{2})(\xi):\mathbb{Q}(\sqrt[p]{2})][\mathbb{Q}(\sqrt[p]{2}):\mathbb{Q}]=[\mathbb{Q}(\sqrt[p]{2})(\xi):\mathbb{Q}(\sqrt[p]{2})]\cdot p$ $\xi$ is a root of $x^{p}-1$. Then $min_{\mathbb{Q}(\sqrt[p]{2})}(e^{{2\pi i}/p})$ divides $x^p-1$. $x^p-1=(x-1)(x^{p-1}+x^{p-2}+\cdots +x+1)$ and $\xi$ is root of $(x^{p-1}+x^{p-2}+\cdots +x+1)$ therefore $min_{\mathbb{Q}(\sqrt[p]{2})}(e^{{2\pi i}/p})$ divides $(x^{p-1}+x^{p-2}+\cdots +x+1)$   According to me, it is true that $min_{\mathbb{Q}(\sqrt[p]{2})}(e^{{2\pi i}/p})=(x^{p-1}+x^{p-2}+\cdots +x+1)$ but  i dont'know proves it  (on another topic I saw that $min_{\mathbb{Q}}(e^{{2\pi i}/p})=(x^{p-1}+x^{p-2}+\cdots +x+1)$ (over $\mathbb{Q})$ but now I need to prove that it is irreducible over $\mathbb{Q}(\sqrt[p]{2})$  Let $\psi:\mathbb{Q}(\sqrt[p]{2},\xi)\to \mathbb{Q}(\sqrt[p]{2},\xi)$ automorphism such that for all $x\in \mathbb{Q},\, \psi(x)=x$.  I need find the extension of $\mathbb{Q}(\sqrt[p]{2})\to \mathbb{Q}(\sqrt[p]{2},\xi)$. Since $x^p-2=0$ implies  (on $\mathbb{Q}(\sqrt[p]{2},\xi)$) that $x\in \left\{\sqrt[p]{2},\sqrt[p]{2}\xi,\sqrt[p]{2}\xi^2,\ldots, \sqrt[p]{2}\xi^{p-1}\right\}$. By  a theorem, exists $p$ extensions (because exists $p$ rootS of $x^p-2=0$) This $p$ extensions are: $\psi_1:\sqrt[p]{2}\mapsto \sqrt[p]{2},\psi_2:\sqrt[p]{2}\mapsto \sqrt[p]{2}\xi,\ldots, \psi_{p}:\sqrt[p]{2}\mapsto \sqrt[p]{2}\xi^{p-1}$  Now, I need find the extension of $\mathbb{Q}(\sqrt[p]{2})(\xi)\to \mathbb{Q}(\sqrt[p]{2},\xi)$. In this case, because $x^{p-1}+x^{p-2}+\cdots +x+1=\min_{\mathbb{Q}(\sqrt[p]{2})}(\xi)$, i have that $x^{p-1}+x^{p-2}+\cdots+x+1=0$ implies $x\in \left\{\xi,\xi^2,\ldots, \xi^{p-1}\right\}$ (therefore, exists $p-1$ extensions) The extensions are: $\bar{\psi}_{1}:\xi\mapsto \xi,\ldots, \bar{\psi}_{p-1}:\xi\mapsto \xi^{p-1}$  By 6) and 7), there are $p(p-1)$ $\mathbb{Q}$-automorphism of $\mathbb{Q}(\sqrt[p]{2},\xi)$. This are:   $\psi_{i,j}:\sqrt[p]{2}\mapsto \sqrt[p]{2}\xi^{i},\, \xi\to \xi^{j}$ where $i=0,1,2,\ldots, p-1$ and $j=1,2,\ldots, p-1.$ I would need to prove that $\min_{\mathbb{Q}(\sqrt[p]{2})}(e^{{2\pi i}/p})=x^{p-1}+x^{p-2}+\cdots +x+1$  and  explicitly find the group of automorphisms (that is, see some group isomorphic to the group of automorphisms found in part 8) How can I find the group? actualization 1. Is $x^{p-1}+x^{p-2}+\cdots+ x+1$ irreducible over irrationals (or in real numbers)? (and, by consecuence, irreducibl over $\mathbb{Q}[\sqrt[p]{2})$


$G$ a group s.t. every non-identity element has order 2. If $G$ is finite, prove $|G| = 2^n$ and $G \simeq C_2 \times C_2 \times\cdots\times C_2$

Let $G$ be a group s.t. every non-identity element has order 2. If $G$ is finite, prove $|G| = 2^n$ and $G \simeq C_2 \times C_2 \times\cdots\times C_2$  I know G is abelian since $ab = (ab)^{-1} = b^{-1} a^{-1} = ba$ for all non-trivial $a,b \in G$ so I have several questions remaining:    How do I prove $|G| = 2^n$? I'd like to say we use induction to prove this but I'm at a loss as to where I would start. Why is $G \simeq C_2 \times C_2 \times\cdots\times C_2$?   I've read several answers to question similar to this yet unfortunately most of them involve Galois Fields and vector spaces, both concepts I'm unfamiliar with. I'd greatly appreciate an intuitive proof.


Prove that $\lim_{n\to \infty} [\int_E f^n (x) dx)]^{1/n} = M$ where $M = \sup_{x\in E} f (x)$

In the book of Mathematical Analysis II, by Zorich at page 128, it is given that     Let $E$ be a Jordan-measurable set of nonzero measure, $f : E →  \mathbb{R}^n$ a continuous nonnegative integrable function on $E$, and   $M = \sup_{x\in E} f (x)$. Prove that      $$\lim_{n\to \infty} [\int_E f^n (x) dx)]^{1/n} = M$$   I have already proved that  $$\lim_{n\to \infty} [\int_E f^n (x) dx)]^{1/n} \leq M$$ since $E$ is Jordan measurable and has nonzero measure, but I'm having trouble proving the reverse of that statement, so any help is appreciated.  Edit:  I'm new to this topic, and I even do not understand the premise of the asked question, so I would appreciate if you could post an answer that is formulated in terms of the statement that I have given in the question.


How many times do I have to play a random fraction of a playlist to hear each song at least once?

Let's say we have a playlist consisting of $N$ songs. Each time I want to listen to music, I pick a random sample of $k\leq N$ different songs ($k$ is constant and deterministic over time) from that playlist and listen to them. Note that in the $k$ songs of one sample there are no duplicates, but the next may contain songs I've already heard in other samples. What is the expected number of samples I have to pick such that I have heard each song of that playlist at least once?  I calculated a simple example, where $N=3, k=2$ and let $X$ denote the random variable representing the number of samples it takes to cover all songs. Then $$ E[X]=\sum_{n=1}^{\infty}n\cdot Pr(X=n)=0+2\cdot\frac{2}{3}+3\cdot\frac{1}{3}\cdot\frac{2}{3}\dots=\sum_{n\geq 2} n\cdot\frac{2}{3}\cdot\frac{1}{3^{n-2}} \\ =\frac{2}{3}\cdot\sum_{n\geq 0}\frac{n+2}{3^n}=\frac{2}{3}\cdot\left(\frac{3}{(3-1)^2}+\frac{2}{3-1}\right)= \frac{7}{6} $$  But if I try to be more general or even only consider a little more difficult example I have problems calculating the individual probabilities as the possible combinations for $X=n$ depend on the previous combinations and I don't know how to take that into account.  Can anybody help me out with that and maybe also verify if my calculations for the example were correct?


The following is an interview question.     Consider a $10$-digit number where first digit is the number of zeros, second digit is the number of ones, etc. What is the number?   I know that the question is related to  and the answer is  $$6210001000.$$ However, I do not know how to deduce the answer.  From the question, we know that the sum of all digits is $10$ as there are $10$ digits.  But other than this equation, what can we obtain?


A novel where contract breach is worse than femicide, from the 70’s or earlier

I read this novel at least 40 years ago.  It is clearly SF, some of the action is not on Earth. I don’t remember interstellar travel, only within solar system, Moon and/or Mars and/or  Venus and/or asteroids. So space colonisation is there, but in fact is a minor ingredient : if those parts of the action had been on some remote corner on Earth, it would not have changed the plot much, really.  What I remember best is some "sociological" aspects. There seem to be no countries, no polities.  Big companies rule the world (the worlds, rather, since there are several inhabited planets/satellites). Even law and order are maintained by private security agencies. I think I remember Brink’s being mentioned.   The main protagonist works for one such big company. He has no decision power, but has the ear of the CEO of that company, who trusts him. Of course, some people are not happy with that.  So one morning the main protagonist  wakes up, probably not on Earth, as an indentured worker (translate : a slave) and is shown a contract he is supposed to have signed to pay back some huge debt he has no memory of owing. And since his expenses are higher than his salary, he’ll never pay it back. I don’t remember how he does it, but he manages to escape, without killing anyone. However he is now wanted by the authorities-that-be for contract breach and “femicide”.   At some point he gets in touch with, either the CEO he worked for, or some person really loyal to the latter. In any case, this person does not blink an eye at the charge of femicide, but asks him whether the contract that was breached really was invalid.  (It is not clear where, in this hierarchy of severity, homicide would find its position.)  At his assurance that the contract was totally phoney, he obtains help, but there are still more happenings that I forgot.   In the end, the CEO dies and the main protagonist is told by a inheritance lawyer that the CEO has willed him a majority of shares of some obscure sub-company. But by some complicated mechanisms, this puts him in control of the entire big company of which he becomes the CEO.


I have a site where some pages are "virtual".  The path is :   internal_node/XYZ   where  * internal_node/% is defined in a hook_menu() * XYZ is a number  my "internal_node" callback  call an external service using XYZ like argument, get soma data and display this data to the user. All works without problem. And all is legal.   Now I want to add all "interal_node" links to my google's sitemap.  I have installed xmlsitemap, but this module create a google sitemap for only all internal drupal node and my "internal_node" are not a drupal node.   So, how can I add link to xmlsitemap ?   Thanks.


How strong of magnetic field would noticibly attract a person?

There is iron in our blood, which is magnetic. Roughly how strong would a magnet have to be to induce a noticeable attraction? It would be nice to know this for several distances. Also, do electromagnets that strong exist?


sports-related questions appearing on SO

probbaly a bug somewhere, but there's a lot of sports related questions popping up on SO, getting voted down real fast and disappearing. probably a glitch in some other stackexchange site? (for example, see )


Strange behaviour with mod(x,4) at pgfplots

Why does mod(x,4) is 4 when x = {12, 24, 32}? should be 0, as in x = 4 and x = 8.   \documentclass{article} \usepackage[a4paper, total={6in, 9in}]{geometry} \usepackage{tikz} \usepackage{pgfplots} \pgfplotsset{compat=1.15}  \begin{document}  \begin{tikzpicture} \begin{axis}[ axis x line = middle, axis y line = left, style={draw=none}, xmin=-0, xmax=32, ymin=-1, ymax=6, width=15cm,height=10cm, ylabel=$y$, xtick={0,1,...,32}, %ytick=\empty, xlabel=t] \addplot+[const plot,samples at={0,1,...,32}] {(mod(x,4))}; \end{axis} \end{tikzpicture}  \end{document}


Prove the integral of $f$ is positive if $f ≥ 0$, $f$ continuous at $x_0$ and $f(x_0)>0$

Prove that $\int_a^b f(x)\,dx  \gt 0$ if $f \geq 0$ for all $x \in [a,b]$ and $f$ is continuous at $x_0 \in [a,b]$ and $f(x_0) \gt 0$  EDIT. Please ignore below. It is very confusing actually -.-    Note: After typing this all out, I think I realized that my proof is complete, but I'll just post it to make sure :)  Attempt:   Find a partition $P = \{t_0,\ldots,t_n\}$ of $[a,b]$ s.t. $f(x)\gt f(x_0)/2$ for any $x \in [t_{i-1},t_i]$  Thus, the lower sum, $L(f,P)\geq x_0 (t_{i}-t_{i-1})/2 > 0$  [Basic Idea: since f is continuous at $x_0$, in the worst case scenario (i.e. $f=0$ at all points except in a nbhd of $x_0$) there must be some "bump" at $x_0$, which prevents the integral from actually equaling $0$. If we can find just one lower sum of a partition to be $> 0$, we will be done (I think...)]


How to get mDNS working for Chrome on Android?

Is there a way to connect to  using Chrome on Android, or is there another browser that works?  I travel from network to network with my laptop and my phone and I often have to connect my phone to a website on my laptop. With Safari on an iPhone I can simply use  (usually hitting reload on an open browser window), but with my Android device I always have to figure out the current IP of my laptop punch it in by hand and connect to it (I don't control many of the networks I'm on and they don't seem to ever have DNS integrated with DHCP).   I've searched a for an answer and it seems most people simply hack around the issues using static DNS, or they control DHCP and DNS, neither of which apply for my situation. Also I see code libraries for supporting mDNS (and other zeroconf stuff) in a specific Android application, so perhaps there's a Chrome add on out  there, or some other browser that supports it?   Also, is there any official word on device wide support for mDNS and the .local domain on Android? I had trouble finding that as well.


How to change the sorting order in view selector?

On a document library (under SP2013) we have created multiple views. In the view selector, the default view is listed at leftmost. All the other views are sorted in alphabetical order based on the view name.  Our user would like to determine the sorting order of view selector. Take below screenshot as example, how can we put the view selector in this order:   Deeds - Permits - All Documents - Agreements    P.S. I have read  and seems a good start but not exactly answer my question.


Number of samples for final render in Cycles

I am rendering with GPU and sample rate is 300 [no ambient occlusion] But i am getting too noise and fog type things here in this image you can see. can you please tell me the best rendering settings for this types of render. also a tutorial about to nice studio light setup.


Does there exist a continuous function $f\colon \Bbb R\rightarrow \Bbb R$ such that $f(f(x))=-x$ for all $x\in\Bbb R$?


Maven how to change dependancy version according to platform configuration (MySQL)

I'm trying to build a JavaFX software application for windows platforms including windows XP, Vista, 7, 8, 10.  I'm using Maven as a dependancy manager to build the project.  In my application, i make use of MySQL Driver for JDBC connectivity. However, when targeting old OS such as XP, i'm obliged to use old drivers because nowdays versions of MySQL are impossible to start on XP.  I need my project to get built with MySQL 5.1.6 Driver for Windows XP platform, and MySQL 5.7 Driver for the rest of platforms.  I'm aware that i can do that by building the project 2 times and proving 2 .jar files and then 2 different .exe files, but is there any other elegant way to do that ?  Thanks in advance.


Convert NTFS to FAT32 without losing data

I understand that you can  without formatting or backing up the data and later restoring - is the same thing possible in the other direction?  I want to convert my NTFS portable hard drive to FAT32 so that my PS3 will recognise it.  If it's not possible from within Windows, are there any free programs which will allow me to do it?


Most user profile pages seem to be failing; activity tab unaffected

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


Noob question: Why do trignometric functions repeat on a graph?

When a sine wave (or a cosine wave) is graphed, it repeats itself at a fixed period. However, the value $\sin(\frac{\pi}{2})$ is geometrically undefined because you can't have a triangle with two right angles. The same argument is true for all obtuse angles. So why do we still graph these and use these values as valid inputs to trignometric functions?


Can I take pictures from posters and slide presentations in a conference?

If I do not ask for permission, is it acceptable to take pictures from posters and slide presentations in a conference by camera? Can I record a presentation?


When does the amount of skew or prevalence of outliers make the median preferable to the mean?

I know that "deviations in the data are devil", and when the distribution is highly skewed, it is better to consider median as average rather than mean, but how to decide these hard-limits.  For example:   CASE 1:   Assume X = 10,20,30,40,50,60,70 In this case, I think that it is better to use mean and that it will give very accurate results.  CASE 2:   Assume X = 10,20,30,40,50,60,70,7000 In this case, I think that it is better to use median instead of using the mean.  CASE 3:    Assume X = 10,20,30,400,500,600,700 In this case, I think it is better to use IQR (Inter Quartile Range)    But I'm stuck with how to decide these hard-limits i.e. which to use in which condition, in general.   I've found a tool working on subjected principle, which takes context-less sample-distribution as input and determines whether mean is close/moderate or against the null-hypothesis.  Find References:-     (For Mean Test)  (For Median Test)   What I'm really looking is a good answer which states how to derive these conclusions.


My space used and free space doesn't add up

See pic - the numbers don't add up!   Screenshot (click for larger variant)  This is a 16GB Nexus 7 The listed items only add up to a little over 9GB. So 4GB worth of files are missing.  How can I find those missing files?


What happens if you fly a drone inside moving passenger airplane?

I have a little question. If I mark an X in the center of a passenger airplane, and try to fly a drone from the X mark in the moving passenger airplane (800-900 km/h), what will happen to the drone?  Is it going to fly up and standstill above the X mark? Or will it fly up above the X mark then gradually heading to the end of the plane? Put aside the FAA rules and something like that.


How to make .append() html content clickable?

I need to make certain "appended" html content "clickable". Here is the code:  function displayContacts(contactArray){         var jsonObject = $.parseJSON(contactArray);         jsonObject.forEach(function (dat) {             //Begin Contact Unit             $('.feed')                 .append('
\

\                 ' + dat.firstName + ' ' + dat.lastName + '

');             //End Contact Unit         }); }   I have a AJAX call not shown that gets 3 pieces of data in JSON. This function then appends that data to an html doc in order to create a list of contacts - in this case it's a master list of every user in the db. My question is: how would I go about making these elements (the images, for example) clickable? The goal is to make this list of contacts in such a way that the user can select one by clicking on the avatar. I have tried using .on, .click, many different things and I think it may require one of those but I am not sure where to place it in the actual code. The way I understand it is these elements are dynamically created, which makes them special.  Thank you for any help - this has really confused me.


Some cards in magic has something happen for each {something}. For instance:  makes you gain 2 life for each creature you control. Tapping  adds one green mana to your mana pool, and you gain 1 life for each non-land card revealed.  How is this life gained: all at once or "one bit" at a time? Say I tap Selvala and 1 land, and 2 non-lands are revealed: do I gain 2 life, or do I gain 1 life two times? Would  have one or two +1/+1 counters placed on it if I had it in play at that point?


Probability enemy territory captured in X turns

I am playing Warlight online (something like Risk), and my goal is to create a bot which plays against other bots.  n=100 attacking troops will on average kill 60 (p=0.6) troops each turn,  n=100 defending troops will on average kill 70 (p=0.7) troops each turn. They attack exactly at the same time. Binomial distribution such that variance=n*p*(1-p)   My question is the following: imagine we have 40 troops and the enemy has 25 troops. I am interested in the case that I continuously attack. What would be the chance that I have won by turn X (e.g. X=5)?  For turn = 1, it is simply the cumulative sum from at least 25 kills:   $$\sum_{i=25}^{40} {40 \choose i} * 0.6^i * (1-0.6)^{(40-i)} = 0.440$$   I have played around with the binomial distribution, but I find it difficult to calculate because of this "in X turns"; it seems it really explodes the amount of calculations needed (by lack of a smart trick).  Can this be done analytically or am I best off just to simulate this (which I assume will be much slower)?  EDIT: Perhaps it can simply be done by using the 60% and 70%?


Looking to sort array from smallest to largest remove duplicates

As the title says, I'm taking a free online course in C# and I've been stuck on this question for a bit. It's asking to write  function with an array that sorts from smallest to largest and removes duplicate entries. The course has gone over arrays and sorting, but not how to remove duplicates so far. If you could help with this I'd appreciate it greatly.


I would like to use git to track changes in crontab.  I have initialized a new git repository in /var/spool/cron/crontabs/  Now the problem is, when crontab is saved, the second line of the header changes because it contains timestamp.  # DO NOT EDIT THIS FILE - edit the master and reinstall. # (/tmp/crontab.ubNueW/crontab installed on Thu Aug  1 06:29:24 2019)   What would be the easiest way to ignore these irrelevant changes ?  The  does not address the main point of my question: How to ignore the first 2 irrelevant lines from crontab. Instead, it addresses some other questions which I have not asked, such as some hooks.


Is it a sane approach to "back up" the $IFS variable?

I am always really hesitant to mess around with $IFS because it's clobbering a global.   But often it makes loading strings into a bash array nice and concise, and for bash scripting, conciseness is hard to come by.   So I figure it might be better than nothing if I try to "save" the starting contents of $IFS to another variable and then restore it immediately after i am done using $IFS for something.   Is this practical? Or is it essentially pointless and I should just directly set IFS back to whatever it needs to be for its subsequent uses?


I have found the command to delete files older than 5 days in a folder  find /path/to/files* -mtime +5 -exec rm {} \;   But how do I also do this for subdirectories in that folder?


Where can I ask "Find a tool"-Questions?

Where can I ask questions like:   "Do you know a tool/program for doing ...?"  "Are there alternatives to the software ... ?"


Why, intuitively, does $log(x)$ come in as the integral of $1/x$, wheras the integral of other powers of $x$ are powers of $x$?

Question in title really, something I always found strange when I was learning calculus.  I can see that $\int \frac{1}{x} dx$ can't be $\frac{x^0}{0}$ since this is not defined, and then the definite integral $\int_1^t \frac{1}{x} dx$ comes down to $$\lim_{\delta \rightarrow 0} \frac{t^{\delta}-1}{\delta} = \log (t).$$   But this understanding just comes from l'Hopital's rule, and also it still just seems really bizaare that the log function should fit into the set of power functions like this.  Can anyone de-mystify this at all?


How do I enable cache of the Google Analytics file to increase my PageSpeed Insights score?

I have the following rule in my .htaccess file:  # 1 Month for most static assets <filesMatch ".(css|jpg|jpeg|png|gif|js|ico|woff)$"> Header set Cache-Control "max-age=2592000, public" </filesMatch>   And I have but when I check my page on Google page insights I still see that one .js file has not been cached , the file the following file:  http://www.google-analytics.com/analytics.js (2 hours)   Now how exactly do I cache this file? How do I cache a Google analytics file?


What is the benefit of "claiming" a Fort or other location for your guild?

Like, does the guild get a collective character buff or ...something? Is it just to look pretty?


Where is earth in relation to the center of the Universe? If we point a telescope in any given direction will we come up with the same distance to "as far as we can see"? Or can we see farther in some direction(s) as opposed to others. If the universe is indeed expanding then we should be traveling further from one part than another, unless we are indeed in the center, thus every part would be moving away from us in a more or less uniform manner.


Finding number of positive integers based on condition given

This problem is from prmo 2021  find sum of all positive integers n for which $|2^n+5^n-65|$ is a perfect square  My method $2^n+5^n-65=\pm m^2$ case 1 $2^n+5^n=65-m^2$ This is satisfied by n=2 only case 2 $2^n+5^n=65+m^2$ This condition gave me value for many n on counting right from n=1 to large number which increases the chance of missing a number. Is there a better way to calculate without actually counting all numbers


Change background of Terminal.app from the commandline

Is it possible to change the background color of Terminal.app from the shell? If so, how?


How to install a CA key (self signed SSL) on ubuntu?

I have a bunch of machines that need to fetch https: off a server (or collection of servers). I'm operating a CA and self-signing the certificates on the server(s).  The client machines are running ubuntu. Some of the fetches are via apt, some via wget.  How do I install the CA's certificate on the clients so that all of its certs are recognized without warnings or errors? (Just the directory location is sufficient, I'll package it in an appropriate way.)  Thanks.


Is there any limit to the number of expressions|parameters in a 'while loop'

Traditional programming with while-loop is done with a single parameter ex:   while(1) (or) while(a==b) (or) while(a&&b) (or) while(!a) etc The code below takes two parameters in the while loop  ssize_t r_read(int fd, void *buf, size_t size)  {     ssize_t retval;     while (retval = read(fd, buf, size), retval == -1 && errno == EINTR);     return retval; }    Is there any limit to the parameters inside the while loop? Is there any possible explanation for this or does this methodology have a name?


Dual citizen, British and Malaysian. Going through a neutral country might be better. Why?

I am a dual citizen, Britain and Malaysian. Right now I am in Malaysia. I will be doing my university degree in the Netherlands this September, and will be away for 3 years.  Can I leave Malaysia, showing my Malaysian passport at immigration, fly to the Netherlands, and at the Netherlands immigration produce my UK passport (because I don't need a student visa and getting a job is much easier)? Then after three years, when I leave the Netherlands, show my British passport there, and at immigration into Malaysia produce my Malaysian passport.  Will there be a problem? Will Malaysia be suspicious of something because I was in the Netherlands for 3 years? I don't want to lose both my citizenships and I don't want Malaysia to find out.  In the question  I read that going through a neutral country might be better.  Note: Malaysia doesn't allow its citizens to also hold other citizenships. If Malaysia finds out that I have a British passport, I will have to cancel one citizenship.


Handling imbalanced data for classification

What are the best ways to deal with imbalanced datasets for classifying whether or not individuals pay their tuition? The data is 75% positive class (paid) and 25% negative (unpaid). Some approaches I have read about include stratified k-folds , undersampling and oversampling, and synthetic data with approaches like SMOTE. One challenge I am currently facing is that my XGBoost classifier predicts almost all positives because there is a class imbalance leaning towards the positive class.  Instead of tackling the imbalance by modifying the data, can certain classification algorithms handle imbalanced data better than others?   Lastly, when is data considered imbalanced from a practical standpoint (60-40, 80-20, 95-5, etc.)? Essentially I am asking whether the mild cases of imbalance are still worth addressing, or only severe ones?


For which Natural $n\ge2$ does this occur with?: $\phi(n)=n/2$


Today I'm checking the system processes. I checked the System Idle Process and it said it started a day ago. How?? Last night my computer is off, without power. How did it start a day ago? Last night my computer is shut down, powered off and unplugged from the power socket. Anyone can tell what is going on?


product distribution of two uniform distribution, what about 3 or more

Say $X_1, X_2, \ldots, X_n$ are independent and identically distributed uniform random variables on the interval $(0,1)$.  What is the product distribution of two of such random variables, e.g., $Z_2 = X_1 \cdot X_2$?  What if there are 3; $Z_3 = X_1 \cdot X_2 \cdot X_3$?  What if there are $n$ of such uniform variables? $Z_n = X_1 \cdot X_2 \cdot \ldots \cdot X_n$?


Cardinal of quotient rings of gaussian integers.

It is known that $\mathbb{Z}[i]$ is a PID and that $\mathbb{Z}[i]/(a+bi)\mathbb{Z}[i]$ is finite for all $(a,b) \in \mathbb{Z}^2\backslash \{(0,0)\}$.  My question :      Is there any result on the cardinal of  $\mathbb{Z}[i]/(a+bi)\mathbb{Z}[i]$ ?


Does blinding a monster neutralize its petrifying gaze?

In a past quest I have awarded a Gem of Brighness as part of a treasure to my PCs. Now in the near future they may encounter some creatures with petrifying gaze, like a Basilisk or a Medusa.  The Gem of Brightness can blind those creatures; will this neutralize their petrifying gaze?


We have a sequence $(x_{n})_{n=1}^\infty$ in a Hilbert space $H$ and we know that:   for every $n \in \mathbb{N}$ holds $\|x_{n}\|\le1$ for every $m\ne n$ holds $\|x_{n}-x_{m}\|\ge r > 0$   How I can show that $r \le \sqrt2$ ?


Auto-linkification of Tags.TagName fails when the tag name contains nonstandard characters

Run the following SEDE query: . All the tags except kyūjitai-and-shinjitai, renyōkei, あれ, and たい-form get auto-linkified. These happen to also be the only four tags that contain characters outside the standard set of allowed characters [a-z 0-9 + # - .]. It would be nice if these would auto-linkify too. (I imagine this is even more applicable for other language sites like  - if you , you find that well over half the tags don't linkify because they contain Cyrillic characters.)


is there a mathematical equation for 2 + 2^2 + 2^3 + 2^4 + 2^5 ...

Is there a mathematical equation for:  2 + 2^2 + 2^3 + 2^4 + 2^5 + ... 2^n  I'm not sure what this type of pattern is called.


Let $F$ be a field, let $p , q$ be two coprime natural numbers and we consider the two polynomials $$ f(X) = \sum_{i = 0}^{p - 1} X^{k i} \qquad \mbox{ and } \qquad g(X) = \sum_{j = 0}^{q - 1} X^{k j} $$ in $F[X]$, where $k \in \mathbb{N}$. If $x$ is an arbitrary element in $F$, how can I show that $\gcd(f(x) , g(x)) = 1$?


Adding pictures to mathematical academic papers

I was wondering if there is this "universal" program that generates a picture of a graph (you make), then exports it to SVG form. The SVG is because I want to export my whole project to PDF, so I need everything to be scalable vectors. I was really curious how do people add different style of graphs, from regular "circles connected with lines/arrows" to graphs of automata like so (Apologies, I cannot make this picture view from the front as I don't have enough reputation):  My question is basically if there are some good (free) softwares to create graphs (any time of graph), so that it would look nice in a PDF, and not pixel-y. Or do they make these on photoshop alone? I was really trying hard to find some, the closest thing I found is  which costs money for SVG, and on top of that, I did not see how to make this automata style. (The automata is just an example of a "bizarre" graph/image, but I really mean all styles) Thank you very much!


Is cafe an English word or a misspelling of café? The same goes for touche and touché.  This isn't the same as  since I'm asking if cafe is a English word, not if I should use a diacritical mark on the "e".


I want to label a table for reference purpose. Can someone tell me what is the command for this?

How can I label a table and then refer it to my latex file?


Given $a_{n+1}=a_{n}+\frac{1}{a_{n}}$, how can I find $\lfloor a_{1000} \rfloor$?

Given $a_{n+1}=a_{n}+\frac{1}{a_{n}}$, and $a_0=5,$ how can I find $\lfloor a_{1000} \rfloor$? I've tried coming up with reasonable bounds, but to no avail (ex. ones like $\sqrt{x^2+1} < x + \frac{1}{x}$ are terrible).  I have looked at the only similar post I can find on this site (), but it doesn't seem to help.  Thanks in advance!


How could an ideal conductor with 0 resistance conduct electricity?

A very simple circuit consist of a resistor, a battery, and some conducting wires connecting the resistor to the battery(assuming resistance of the conducting wire is $0$). It is always assumed that both the ends of the conducting wire, i.e. one connecting to battery's terminal and other connecting to the terminal of resistor, are at equal potential and hence the potential difference is zero.   If the potential difference is zero inside conducting wire, then it implies that electric field inside the conductor must be zero. If this is the case then why does an electron inside the conducting wire move, and why there is current flowing through the wire?  My Idea  If the electric field inside conducting wire is zero then it only means that electrons inside conducting wire are not accelerating but can move with a constant speed and since current is the rate of flow of charge per unit time, so it is possible for electric current to exist in the conductor.


Let $E$ be an extension field of $F$. If $a \in E$ has a minimal polynomial of odd degree over $F$, show that $F(a)=F(a^2)$.  let $n$ be the degree of the minimal polynomial $p(x)$ of $a$ over $F$ and $k$ be the degree of the minimal polynomial $q(x)$ of $a^2$ over $F$.   Since $a^2 \in F(a)$, We have $F(a^2) \subset F(a)$, then $k\le n$  In order to prove the converse:  $q(a^2)=b_0+b_1a^2+b_2(a^2)^2\ldots+b_k(a^2)^k=0$   implies   $q(a)=b_0+b_1a^2+b_2a^4\ldots+b_ka^{2k}=0$ Then   $p(x)|q(x)$, because $p(x)$ is the minimal polynomial of $a$ over $F$.  If I prove that $n|2k$ we done, since $k$ is odd, we have $n|k$ and $n\le k$ and finally $n=k$.  So I almost finished the question I only need to know how to prove that $n|2k$ It should be only a detail, but I can't see, someone can help me please?  Thanks


How to automate a webbrowser that supports javascript?

I have to automate the "imitation" of a "human" by using a webbrowser that supports javascript.   I need it because there is a javascript link on the website that can be only used if the webbrowser supports javascript, so curl/wget cannot do it.   Question: How can I do this on a Linux terminal? Or is it impossible?


Epson LX-310 not working after Cumulative Update 2017-11 Windows 10

I have Windows 10 Pro x32 and an Epson LX-310 printer that was working. Yesterday, Windows 10 automatically updated with 2017-11 Cumulative Update for Windows 10.   Today, I cannot print. The printer status is on. When I click "Print a test page", it quickly says the test page has been sent but the printer does not print it.   My printer is connected to a USB port. What wrong with my Windows 10?


What is the difference between Hamburger icon and Ellipsis icon?

I'm working on an enterprise application with a possible responsive design in future. What is the difference between the hamburger icon (3 horizontal bars) and the Ellipsis (3 horizontal / vertical dots)? Can a screen have both the icons together - once being primary navigation and the other being a secondary actions button (could be additional information or actions etc)?  Any insights would be very helpful!  Thanks!


Do serious grammarians endorse the "Can I"/"May I" distinction?

Just now, I wanted to ask a question that was something like, "Can I get a thorough list of all the parts of speech that a sentence can be broken down into?" But then a nagging voice appeared in my head and said,  "Of course you can! You certainly have the capability -- but that's not what you want, is it." "You're asking for help, so use may."  My question is: Should I invariably trust that voice, instilled in students by grammar school teachers everywhere? What do serious linguists and language enthusiasts think about the "Can I"/"May I" distinction?  Would they agree, or is it fair to say that using "can" there has become proper idiomatic English? I ask because I couldn't really think of a quick way to rephrase that sentence using "may", and began to wonder whether it was just another one of those kludgy myths megalomaniac teachers enforce on their students...


Nonzero rationals under multiplication are not a cyclic group

Are nonzero rationals under multiplication cyclic?   Here's my thinking:   They are not. The generator must be a rational $q = a/b$, $a$, $b$ integers with no common factors. Assume $a/b$ generates $\mathbb Q\setminus \{0\}$, then $q^n = a^n/b^n$ or $(1/q)^n = b^n/a^n$. This is impossible since we can find a prime (there're infinitely many of them) that doesn't divide either $a$ or $b$, which have a finite number of prime factors. Not sure if it proves it though.


Proving that $G$ is a group if $a*x=b$ and $y*a=b$ have solutions.

(Reference : Fraleigh, A first course in abstract algebra)     Prove that a nonempty set $G$, together with an associative binary operation * on $G$ such that $a*x=b$ and $y*a=b$ have solutions in G, $\forall a,b\in G$, is a group.   Because * is an associatie operation, we have to prove that: there exists $e\in G$ such that $e*a=a=a*e$ for any $a\in G$, and that for any $a\in G$ there exists $\alpha \in G$ such that $a*\alpha=e=\alpha *a$.  This is very confusing, first I tried to prove the identity exists. If we consider a=b, then $a*x=a=y*a$, and because of the hypothesis $x,y\in G$ always exists, now we have to show that $x=y$, but I just can't do this with out inverses, so I tried to prove that the inverses exists, however I have no idea how the identity looks like, I'm stuck.  And I tried to get unstuck, so I thought particular cases, first if $G$ had only one element, then what would happend if it had just two elements... but I remembered that we don't know if G is finite or not, and I think this makes things a little bit more complicated.  What can I do?