The conga page is getting there,But Facing error Parameter Id missing?

when i select the records in vf page ,after click on the VF Button the conga should be call along with id for generating the PDF but on button click the window is opening but showing error that "ID Parameter is missing" ?  VF Page:  <apex:commandButton value="Generate Invoice" action="{!GenerateInvoice}"  onclick="openConga()" reRender="table1"/>  <Script Language="JavaScript">               function openConga()                  {                      window.open('{!URLFOR($Action.Payment__c.Generate_PDF, Payment_Id)}', '','scrollbars=yes,menubar=no,height=600,width=800,resizable=yes, toolbar=no,location=yes,status=yes');          </Script>     Controller:  public PageReference GenerateInvoice()              {             selectedEsr = new List<Payment__c>();             for(wrappayment wp : paymentList)                 {                     if(wp.selected == true)                      {  Payment_Id=wp.pay.id;   }         }          return null;             }


This is a (soft!) question for students of set theory and their teachers.   OK: ZFC is the canonical set theory we all know and love. But what other, alternative set theories, should a serious student encounter (at least to the extent of knowing that the theory exists, and about why it is thought interesting)?  Suggestions might be SP (Scott-Potter), NBG, NF, ZFA, IST, ETCS (for a few sentences of explanation, see   But what would be on your list of alternative set theories would be it good for advanced students to hear about, if only briefly?


Overriding the equals method - having trouble

guys and/or gals.  I'm having some trouble with this programming assignment for my Programming 2 class.  I feel a bit ashamed that I'm so lost since I seemed to excel in the prior class.  I apologize in advance for what is most likely a trivial problem, but I'm having trouble applying any solutions I find online to my specific code.  Long story short, I've got a Car constructor that has two strings for a make and model (i.e. Honda, civic, respectively).    public Car(String make, String model, double basePrice, String plateNum) {     this.make = make;     this.model = model;     this.basePrice = basePrice;     this.plateNum = plateNum; }   In order for the equals method to function, the cars must have the same make and model.  Here's what I keep messing with, but it always returns false.  @Override public boolean equals(Object other) {     if(!(other instanceof Car))         return false;      Car temp = (Car)other;       if(this.equals(temp.getMake()) && this.equals(temp.getModel()))         return true;     else         return false; }   I've tried it without the "not" in front of the instanceof if statement, and I've tried inverting the this and temp, to no avail.  I know giving out answers to homework is frowned upon, and I understand it completely.  If not, perhaps someone could be kind enough to explain what I'm doing wrong?  I'm not entirely sure what "this" means.  I imagine that it is essentially a placeholder for what will be calling the method.  In this case, it would be a CarObject.equals.  Anyway, thank you again in advance.  This website has helped me out many times in the past, I'm looking forward to any replies. :)


What are useful tricks for determining whether groups are isomorphic?

In general, it is not too hard to find isomorphisms between two groups when their order is relatively low. However, as their orders grow, it becomes increasingly irritating to write down their entire Cayley tables and such. Is there a set of tricks that is generally useful when trying to prove that two groups are actually isomorphic? After all, it usually seems easier to prove that they aren't, as you just need to point out one property that doesn't correspond...  Example: in Armstrong's Groups and Symmetry, it is asked to show that the dihedral group of order 8 and the subgroup of S4 generated by (1234) and (24) are isomorphic. It is easy to send D4's "single-rotation" element r to S4's (1234) and D4's "flipping" element s to S4's (24), as they are all part of the generating set and their orders coincide, but what is the way to go from here? Also, how far should one go in showing the isomorphism - might pointing out the correspondence in generating elements even be enough?


I was looking for a tree or graph data structure in C# but I guess there isn't one provided.  explains a bit about why.  Is there a convenient library which is commonly used to provide this functionality?  Perhaps through a strategy pattern to solve the issues presented in the article.  I feel a bit silly implementing my own tree, just as I would implementing my own ArrayList.     I just want a generic tree which can be unbalanced.  Think of a directory tree.  C5 looks nifty, but their tree structures seem to be implemented as balanced red-black trees better suited to search than representing a hierarchy of nodes.


Our 3 month old wakes up almost every hour through the night and wants to breastfeed only to wake up again 1 hour to half hour later

We are new parents to our first baby boy. When we got home from the hospital 3 1/2 months ago, our baby cried a lot when put down, and just wanted to be held. He hated swaddling so after trying every swaddle we unswaddled.   Now fast forward 3 months, 12 days and our baby is waking up 6 to 7 times after 1 am looking to be fed, sometimes every hour to half hour.   They won't sleep through the night. Why is this happening?


I have a program where I generate a folder, its subfolders and files, and when I click the file, it has to show its content. My problem is that when I click, the function isn't called.  This is my function:       function printFile(params) {             //alert("Hello");             $.ajax({                     method: "GET",                     url: "getFile.php",                     data: {                         q: params                     }                 })                 .done(function(msg) {                     $("#continut").html(msg);                 });      }      window.onload = function(){         //alert("Hello");         $("li").click(function() {              printFile(this.id);         });      };   This is the body:  <?php     function listAll($path, $test) {          $fileList = glob($path);          //Loop through the array that glob returned.         foreach($fileList as $filename){         $pieces = explode("/", $filename);         if($test == 0){         if (strpos(end($pieces), '.') !== false) {         echo '
'.end($pieces)."
", '
';          }         else         echo '
'.end($pieces).'
', '
';          }         else         {         $spaceValue = 40*$test;         echo '
';         if (strpos(end($pieces), '.') !== false) {         echo '
'.end($pieces)."
", '
';          //echo $path;         }         else         echo '
'.end($pieces).'
', '
';          echo '
';         }         listAll($path.end($pieces)."/*", $test+1);         }     }      listAll("D:/xampp/htdocs/*", 0);    ?>   And this is getFile.php:  <?php       $val = $_GET['q'];      $fh = fopen($val,'r');     while ($line = fgets($fh)) {         echo($line."
");     }     fclose($fh);   ?>   What can I do to call the function printFile on generated li?


Find $\lim_{x\to\infty}\left( \sqrt{(x+a)(x+b)}-x \right)$ where $a,b \in \mathbb{R}$

Find the value of the following (using an epsilon proof or basic limit properties (no L'hospital)):  $$\lim_{x\to\infty}\left( \sqrt{(x+a)(x+b)}-x \right)\forall a,b\in\mathbb{R}$$  I've tried rewriting it in several ways, but I don't seem to bet getting very far; I always end up with something in indeterminate form.  How can you prove the value of this?  Any hints?


I did this once, but I can't find instructions how to do that again. It was probably kernel option that make live cd save in ram.  I have old Xubuntu but want to install nested version of Xubuntu, I've downloaded the iso on my old laptop but it have broken DVD, so how can I run live CD, of old Xubuntu, put it in RAM so I can put empty DVD and then burn new Xubuntu?


Can there be more than one power series expansion for a function.

I guess the answer is NO, for polynomials.  I know that there are more than one series expansion for every function.  But I am talking about power series here.  All Ideas are appreciated


how to send a list of integer values into prepared statement

I have been looking for sending a list of integer array into prepared statement, but i was unable to do it. can somebody help me do it.  my code as follows:  public int  Verify(int[] val) {   try { if (connection != null) {     pstmt = connection.prepareStatement("select cola from tableA where val in(?)");     pstmt.setInt(1, val);     rs = pstmt.executeQuery();   i know this wont work.can someone help me to send all values in array at one into "?".  Any help could be greatly appreciated.


What is the difference between "testing" and "quality assurance"?

Is there a difference between "testing" and "quality assurance"?  If so, what are the main goals of each process?  What are the critical differences?


Is it possible to separate professional Stack Exchange accounts from personal ones?

to  reminded me of something I have been trying to work out how to do for a while.  At the moment I just have one SO/SX account with one OpenID and both work and personal accounts all linked together. This is easy and simple, but means that during the day I get Inbox notifications for things which I only want to deal with out of work hours. Similarly, at home I get notifications for things which I want to deal with at work.  So, I'm considering trying to separate my work and personal Stack Exchange worlds, but I'm not even sure if this is possible now the accounts are all linked, without creating all new SX accounts.  I suspect that at the very least I will have to create a new OpenID with a different OpenID provider, add this openID to all of my personal accounts, update my display names on all of those accounts and then remove the original OpenID from them, but what else might I have to do?  Will switching them to another OpenID be enough? Or will the accounts all still be linked together? Has anyone done this, and if so, are there any issues I need to consider?  Note, I'm aiming for the two sets of SX sites to be completely disjoint. No site in my professional account will also be in my personal account and vice-versa, so no problems with appearing to be a sock-puppet. Also, obviously, I don't want to have create entirely new accounts for the SX sites I consider personal and have to start acquiring rep on them from scratch.


Where does the phrase "that tracks" come from?

I'm wondering where "that tracks" comes from, i.e. meaning "that makes sense". I've done a bit of Googling and all I could find was a Reddit post with a bunch of different guesses that all seem plausible, but I was hoping to get a more certain answer.


I have just learnt about the chain rule but my book doesn't mention a proof on it. I tried to write a proof myself but can't write it. So can someone please tell me about the proof for the chain rule in elementary terms because I have just started learning calculus.


Comma with 'who' in this specific sentence

Can you shed light into this?  The coach came to the defence of the player who has been sacked from the team following his differences with the captain.  OR  The coach came to the defence of the player, who has been sacked from the team following his differences with the captain.  Isn't the subordinate clause that begins with 'who', non-restrictive?


I'm working on an idea for a trading game. Players would be traders buying in place A and selling in place B, hopefully for a profit.  I want prices to be dynamic, based on demand and supply. So if place A produces less food than it consumes, prices for food would he high and getting higher the closer they get to running out, while in place B, which has much more production than supply, prices would be near the production cost (minimum price). But if someone buys up a lot of the supply in B, prices would rise, and if someone sells a lot in place A, prices would drop.  Obviously, there are many ways to game such a system if it's not well-designed. The most easy is to empty the market, wait for the price to adjust, then sell everything back.  How could I design this system? I mean the actual math and functions, not philosophical musings. I searched a lot and haven't found anything specific.  I found  but it and its answers are a lot more specific to the specific formula the guy uses in his game. I'm looking for a more generic approach (I want different price elasticity for different goods, maybe non-linear price curves, etc.)


I just noticed something in a rather innocuous text that I was sending a friend. The word "Left", for instance, could mean, "Hey, have you left already?" or "Is anyone left here?". Both these meanings are completely different from each other even if they are using the same word(in this case, "left").  My question is, "Does anyone know more of such words? And if so, is there a specific term for them?"


What does anonymous subclass mean in java?

Recently, I'm learning about JSON, using Google's Gson. And I come across a problem. Here is code:  Type type = new TypeToken<Collection<Data>>(){}.getType();   I can't understand what {} really mean.So I read source code, and get class description like: Constructs a new type literal. Derives represented class from type parameter... Clients create an empty anonymous subclass. anonymous subclass really make me confused? Can anyone explain it concretely?


Is it possible to make a recursive SQL query?

I have a table similar to this:  CREATE TABLE example (   id integer primary key,   name char(200),   parentid integer,   value integer);   I can use the parentid field to arrange data into a tree structure.  Now here's the bit I can't work out. Given a parentid, is it possible to write an SQL statement to add up all the value fields under that parentid and recurse down the branch of the tree ?  UPDATE: I'm using posgreSQL so the fancy MS-SQL features are not available to me. In any case, I'd like this to be treated as a generic SQL question.  BTW, I'm very impressed to have 6 answers within 15 minutes of asking the question! Go stack overflow!


Prove $\lim \frac{cos(x)-1}{x} = 0$ without l'Hopital

While deriving $\frac{\rm{d}}{\rm{dx}}\rm{sin}(x)$, using the definition of the derivative and expanding $\rm{sin}(x+h)$ leads to $\frac{\rm{d}}{\rm{dx}}\rm{sin}(x) = \rm{sin}(x)\lim_{h\to 0} \frac{cos(h)-1}{h} + \rm{cos}(x)lim_{h\to 0}\frac{\rm{sin}(h)}{h}$ The second limit can be evaluated by applying the squeeze theorem, and if I wasn't going from first principles I could use l'Hopital's rule for the first limit, but that would be circular logic. How can I evaluate $\lim_{h\to 0} \frac{cos(h)-1}{h}$ without l'Hopital?


Cannot open C, C++ and Objective-C compiler(clang) on Ubuntu

I was on the Ubuntu Software Center and downloaded "C, C++ and Objective-C compiler(clang)." I didn't see it anywhere so i went to "search your computer and online resources" and didn't see it anywhere. I went to Ubuntu Software Center and went to the "installed" tab and searched for it. But it was not there (by the way it said that it was installed when I searched for it again except this as in the all software center in Ubuntu software center). This was weird and annoying so I went to terminal and entered open  C, C++ and Objective-C compiler but it said that it couldn't get a file descriptor referring to the console. All helpful answers will be fully appreciated.   BTW my question is not a duplicate of "How can I know what programs some apt-get package contains?" as suggested by muru as one question is asking about how can they know what a package contains where my question is asking about where my download even is, obvious difference


Cannot install Xtreme Download Manager on Ubuntu 17.10 from NoobsLab PPA

I want to install xdman on Ubuntu 17.10 but it's not installing.  I ran the following commands :  sudo add-apt-repository ppa:noobslab/apps sudo apt-get update sudo apt-get install xdman


How to pass array of strings dynamically to SQL "IN" clause in Java?

I have a array of Strings "String[]" with certain values. I want to pass that array dynamically to SQL "IN" clause something like:  Select * from Employee where emp_name in (?);   Here "?" has to replaced with String Array. I want to do this in Java Class. I tried with   Array array = conn.createArrayOf("VARCHAR", new Object[]{"1", "2","3"}); pstmt.setArray(1, array);   But it is not working and getting exception "SQLFeatureException".  Thanks!!!


how to check my jtable if null pointer? my code is always null pointer and then can't export to xls. this my code  if (tbGudangSales.getValueAt(i, 5).toString().trim().length() == 0) {                         status = "tidak ada penjualan";                     } else{                         status = tbGudangSales.getValueAt(i, 5).toString();                     }                      label = new Label(4, baris, status, bordertabel);                     excelSheet.addCell(label);   this my error   this my value table


What's a clean and efficient JavaScript implementation to strip leading and trailing spaces from a string?   For example:  " dog"  "dog "  " dog "  "           dog "  all get turned into  "dog"


Server was hacked. Now login wont accept 'root' as username comes up invalid

On Fedora, root is coming up invalid.  WHat is solution?


There are situations, where it is practical to have a type-cast return a null value instead of throwing a ClassCastException. C# has the as operator to do this. Is there something equivalent available in Java so you don't have to explicitly check for the ClassCastException?


Microsoft Exchange 2013 is not receiving internet email

We are having issues with our exchange 2013 server. The server is running Windows Server 2008 R2 Standard.  The issue we're having is that our Exchange server isn't receiving internet emails. It can currently send mail out to internet addresses, and send and receive internal emails from the current email server. I have checked the settings of the receive connectors and everything seems correct. We have tried everything that we can think of.   We can send and receive email locally, and send out to a gmail account. However, we don't get the reply email from the gmail account to the inbox.    Thanks in advance!! Image is of the DNS settings on the exchange server.


Finding solution of non linear DE $x\ddot{x}-\dot{x}^2=1$

I am looking for help on how to find the solution of the following differential equation,  $$x\ddot{x}-\dot{x}^2=1,$$  which comes from solving the Euler-Lagrange equations for the lagrangian $L=x\sqrt{\dot{x}^2+1}$. It is from an exercise in my field theory course. My professor provided me with the solution $x(t)=c_1\cosh{\left(\frac{t-c_2}{c_1}\right)}$, which is a solution when plugged into the equation, but does not give any derivation.   Is there a way to solve this DE other than an educated guess? If so how?


Ubuntu software can't show any app in ubuntu 20.04

After upgrading from ubuntu 18.04 to 20.04 ubuntu software can't show any apps.


How to get a tool that can only break specific blocks and has a name?

So, right now I'm using this:  /give @p minecraft:diamond_pickaxe 1 0 {CanDestroy:[minecraft:stone]}   But I need one that also has the Name value. Anyone know this one?


Is every finite extension L/K separable?

I'm trying to determine whether this statement is true or false. However I only understand that every finite extension of a finite field is separable from another solution. ()  So what difference is finite or not with regards to the finite extension being separable or not?  Thank you


I just noticed that the FAQ link at the top of the page is replaced with "help". However, the description of the Analytical Badge is still "Visited every section of the FAQ". Shouldn't this also be changed to "Visited every section of the helpcenter" or something like that?  Also how will this badge be awarded now? Do you have to click on every link in the helpcenter to get this badge or do you just have to take the tour now?  Update: The description of the tag is now Visited every section of the FAQ (retired) so the issue is solved!


How can I vertically center a "div" element for all browsers using CSS?

I want to center a div vertically with CSS. I don't want tables or JavaScript, but only pure CSS. I found some solutions, but all of them are missing Internet Explorer 6 support.
Div to be aligned vertically
   How can I center a div vertically in all major browsers, including Internet Explorer 6?


Consider the group $G=\langle a,b \mid a^2=b^3=1 \rangle$.  I would like to show that $G$ is infinite by finding a homomorphism $\phi :G \rightarrow \mathbb{Z}$ and showing that this homomorphism is surjective. I am not sure how to define the map $\phi$.


URLs wrapped in  are not parsing correctly in comments

In the comments on StackOverflow,  was misparsed to include the trailing angle bracket.  Also there was a semi-colon after it for some reason.  See my comment below for an example.  In , three ways are suggested to indicate that a bit of text is a URL.   Angle brackets like <http://en.wikipedia.org/wiki/Inotify> Quotes like "http://en.wikipedia.org/wiki/Inotify" Whitespace like http://en.wikipedia.org/wiki/Inotify   Angle brackets are "especially recommended" in the RFC.  Markdown syntax also  and SO's .  The  doesn't say comments auto-link differently.  Comments do auto-link, why do it different?  Thanks for looking.  I know free-form URL parsing is a pain, I maintain a library myself.  UPDATE:  As you can see in this example --  -- the posting grammar knows how to deal with URLs in angle brackets.  Why not in comments?  They both do auto-linking.  Unless there's some other benefit to the user they should do them the same to avoid confusion.  This allows users to learn just ONE set of quirks, not two.


It has been almost a week as Apple has disabled downloads from  due to a security breach.  If you don't have App Store set up for whichever reason, how are you supposed to be using your brand new Mac for development?  Is there a copy of Xcode hidden somewhere within a brand new mid-2013 MacBook Air?  How do I get Xcode if I don't have an App Store account?  Nothing works without Xcode, I can't even use MacPorts to install the stuff I need, because it all depends on Xcode.


Is it possible to search by posts that contain an image?

Sometimes when going back through e.g. my previous answers to find some information, I know the question I am looking for contains an image, and I know the language tag, but I'm a little hazy on the other parameters.    Is there a search option to restrict results to only those posts that contain an image? Akin to filtering email to show only those with attachments I guess.  I see that with  you can filter by user, votes, answer count or whether a question has an accepted answer, or has been closed or migrated. But not images?


Why is $Q=p$, $P=-q$ a canonical transformation from the perspective of 2 variational principles satisfying boundary conditions?

This is to ask a more general question: Landau-Lifshitz say that for the variational principles $$\delta\int_{t_1}^{t_2}p\mathrm{d}q-H\mathrm{d}t =0$$$$ \delta\int_{t_1}^{t_2}P\mathrm{d}Q-H'\mathrm{d}t =0$$ to be equivalent, the difference $(p\mathrm{d}q-H\mathrm{d}t)-(P\mathrm{d}Q-H'\mathrm{d}t)$ must equal the differential of a certain function $F$ of $q,p$, and $t$. I would agree if $F$ were a function of $q$ and $t$ alone since the variational principles above are taken among $q,p$ such that $\delta q(t_i)=0$, $i=1,2$ so adding $\mathrm{d}F$ to the integrand adds a constant to the integral and the variational principle doesn't change. But in the case where it can depend on $p$ I don't see why. For instance in the case $Q=p$, $P=-q$, why would $\int_{t_1}^{t_2} \mathrm{d}(pq)$ be a constant?


Produce two distinct topologies of R such that the first is strictly finer than the second but the two are homeomorphic to each other.

Need to prove that they are homeomorphic to each other.  So if T_1 and T_2 are topologies on set X with T_1 contained in T_2, every element of T_1 will be in T_2 and T_2 is the "finer" (stronger and larger) topology. So to them be homeomorphic is T_1 going to have to be a hole in T_2?


Sending a notification popup in winforms from another thread

I've run into a unique little error in my basic chat program which states that I cannot send a  from another thread:  An exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll but was not handled in user code  Additional information: Cross-thread operation not valid: Control '' accessed from a thread other than the thread it was created on.   This occurs when I call popupNotification.Popup(); from this method:  void ChatServer_OnDataReceived(object sender, ReceivedArguments e)     {         string machine = e.Name;         string message = e.ReceivedData;         popupNotification.TitleText = "New  message";         popupNotification.ContentText = machine + " sent a message at " + DateTime.Now.ToShortTimeString() +             ", saying  \"" + message + "\"";         popupNotification.Popup();         changeTextBoxContents(e.Name + " sent a message at " + DateTime.Now.ToShortTimeString() +             ", saying  \"" + e.ReceivedData + "\"");     }   I'm trying to create the cross-thread code which should look like this:  public delegate void UpdatePopup(PopupNotifier notificationPopup);  void sendAPopup(PopupNotifier notificationPopup)     {         if (notificationPopup.InvokeRequired)         {             Invoke(new UpdatePopup(sendAPopup), new object[] { notificationPopup });         }         else         {             notificationPopup.Popup();         }     }   However, the notification popup window library doesn't have a Invoke Required method, so I'm out of luck on that fix.  Can anyone help?


How to recursively remove execute permissions from files without touching folders?

I made a backup to an NTFS drive, and well, this backup really proved necessary. However, the NTFS drive messed up permissions. I'd like to restore them to normal w/o manually fixing each and every file.  One problem is that suddenly all my text files gained execute permissions, which is wrong ofc. So I tried:  sudo chmod -R a-x folder\ with\ restored\ backup/   But it is wrong as it removes the x permission from directories as well which makes them unreadable.  What is the correct command in this case?


Mortarboard badges being awarded as a result of bounties after recalc

(Preface: I'm not on a badge witch hunt or anything, just saw something peculiar and potentially buggy)   recently got Mortarboard but , and that was 3 months ago.   states that Mortarboard is earned by        Exceed the rep cap         Exceeding the cap is defined as earning ≥200 reputation in one day from a combination of upvotes and accepts, but not bounties         But there's been no days like that as far as I can tell.  Is this a bug?  edit: and also the answer that got upvotes on the day of that bounty was to a CW question that's always been CW (plus, he would have gotten 250 + the upvote rep since the bounty is immune to the rep cap)


Special Parameter query - multiple used to obtain command name?

In a uni text provided us to cover bash scripting, the following variable assignment has got be stumped and I've yet to get an answer back from anyone, hence hopefully someone on here can help.  name=${0##*/}     This should expand to provide the name of the command entered. I can see how this is taken from argument $0, as the first character in the braces is 0. However, according to the information on the previous page (of said uni doc) and to sources I've looked at on the web so far, # means the number of arguments the script was called with, and * contains the argument as a string.  I just can't understand how these all of these special parameters are expanding only to argument $0.  I'd expect the name to expand to: code/script2 3 3 code/script2 fred george allison.  I'd really appreciate it if someone could explain what each of the special parameters between the braces is doing in order to expand to the name: code/script2  Thanks for your help in advance!   Below is the entire script and output for context:  1  #!/bin/bash 2  # A simple script showing some of the special variables 3 4 echo "The full name of this script is $0"  5 6 name=${0##*/} 7 8 echo "The name of this script is $name" 9 10 echo "The process ID of this script is $$" 11 12 echo "This script was called with $# parameters" 13 14 echo "The parameters are \"$*\"" 16  echo "Parameter 1 is - $1" 17  echo "Parameter 2 is - $2" 18  echo "Parameter 3 is - $3"  prompt: code/script2 fred george allison The full name of this script is code/script2  The name of this script is script2 The process ID of this script is 3501 This script was called with 3 parameters The parameters are "fred george allison" Parameter 1 is - fred Parameter 2 is - george Parameter 3 is - allison


D&D 5e Warlock Multiclass - Casting Warlock Spells Using Other Class Spell Slots

If I'm playing a level 5 character with Spellcasting and multiclass to gain level 1 Warlock gaining Pact Magic, can I use my primary spell slots to cast my Warlock spells?  For example, is casting Hex using one of my 3rd level slots allowed?


I'm trying to draw a truth table from the digital logic circuits, I suppose the one on the left is right, but the one on the right is confusing and I'm lost on how to start. I did some labeling and I'm unsure on this.


Is there a simple way of proving that $\text{GL}_n(R) \not\cong \text{GL}_m(R)$?

Letting $\mathbb{F}_{1}$ and $\mathbb{F}_{2}$ be fields, and letting $n \geq 3$ and $m$ be natural numbers, it is known that $\text{GL}_{m}(\mathbb{F}_{1})$ and $\text{GL}_{n}(\mathbb{F}_{2})$ are elementarily equivalent if and only if $m=n$ and $\mathbb{F}_{1} \equiv \mathbb{F}_{2}$ (as proven in "Elementary Properties of Linear Groups" in the collection "The Metamathematics of Algebraic Systems — Collected Papers: 1936–1967").  So, given a field $\mathbb{F}$, if $n \neq m$, then $\text{GL}_{m}(\mathbb{F}) \not\equiv \text{GL}_{n}(\mathbb{F})$, and thus $\text{GL}_{m}(\mathbb{F}) \not\cong \text{GL}_{n}(\mathbb{F})$.  Letting $R$ be a commutative ring (with unity), and letting $n, m \in \mathbb{N}$ be such that $n \neq m$, is there a simple "algebraic" way of proving that $\text{GL}_{m}(R)$ and $\text{GL}_{n}(R)$ are not isomorphic (as groups)? Is there a simple group-theoretic way of showing that $\text{GL}_{m}(\mathbb{F}) \not\cong \text{GL}_{n}(\mathbb{F})$ for a field $\mathbb{F}$?  Certain special cases of this problem trivially hold, for example in the case whereby $\mathbb{F}$ is finite, in which case $|\text{GL}_{m}(\mathbb{F})| \neq |\text{GL}_{n}(\mathbb{F})|$.


How do I completely uninstall Google Chrome and Chromium?

I'm having a problem with Chrome and one of its extensions, so I want to completely uninstall everything. I've uninstalled Chrome through the Software Center, but when I reinstall it, all of my extensions and preferences are still there.   If I want to start over from scratch, what do I need to do?


Laptop battery maintainence with proper guide

How do I proper use my laptop battery??currently I am using windows 8 in my lenovo b590 model. I am confused with its power plan mode(balanced & power saver). In which options I should go , whenever I am using my system in charging mode or in battery mode?? & please write to me it's charging & discharging procedure.Thank You for your support as always.


Is it possible to have a look at all .net objects which are collected upon calling GC.Collect()?  I need to see what objects are still in memory and not reclaimed, so I can find where reclaiming the objects should have done manual, but was forgotten by the programmer. I don't want to call GC.Collect because someone somewhere forgot to dispose an object which blocks some handles.


First Q here. If this has been asked before sorry (Did search)  Term for a choice that you like and you dislike? And you can/would probably only take the choice you like.  For example:  A justice department lawyer says to you "Either testify or go to prison for 25 to life". Or "Enter witness protection or Vito is going to put you in the ground".  In the above statements, we have two choices. But only one choice is viable. "To testify", or "Enter witness protection".  What is such a choice called? (It can not be called a dilemma).


AIC/BIC for model selection between GLM and LM?

I've got a couple different models (poisson regression vs. OLS linear model on log-transformed DV) and trying to compare the two. They both provide reasonably good fit to the data.   I have heard people state that you cannot use AIC/BIC to compare these two but cannot seem to find a reference to this effect. They are different kinds of models, so I'm curious to know how one should go about making the decision between them.


Interstellar: Can someone explain the ending?

I don't know an awful lot about physics but I'm educated enough and have read/watched/played enough SciFi to understand the basics. It is my understanding that oxygen is running out causing people to eventually die of lack of oxygen plus crops are dying. So in the end, how did whatever was tapped in Morse Code to Murphy enable her to do what she did? And I should probably also ask what it was that was tapped to her as well.


Loading .bib files with BibLaTeX on Overleaf

I am switching an existing file on Overleaf from BibTeX to BibLaTeX.  I have .bib files in the folder with the file (imported from JabRef) which worked just fine with BibTeX.  For some reason, BibLaTeX is not loading them; in other words, it does not recognize any of the bibtex keys cited in the text.  My format is: \addbibresource{filename1.bib,filename2.bib}  Anyone know why this isn't working?  I have found people talking about stuff like biber, which I don't really understand.  And I can't see how to do that kind of thing in Overleaf.  I tried adding [backend=biber] to the package line but that didn't change anything. Thank you! P.S. I am switching because I would like to have abbreviated reference lists as described here:  UPDATE: Following @DavidCarlisle's point, I now have the format: \addbibresource{filename1.bib} \addbibresource{filename2.bib}  Surprisingly, the bibtex keys in the text are still not recognized. The error message reads, "Package biblatex Warning: Please (re)run Biber on the file: output and rerun LaTeX afterwards." I thought I would provide this update, but moewe has kindly helped me solve my end goal (mentioned as P.S. above) in a different way:


Proving an entire, complex function with below bounded modulus is constant.

How would I show that an entire function $f$ with the property $|f(z)| \geq 1$ must be constant?    I'm aware of Liouville's theorem, just not sure how to apply it here.


Gateway GT5228 Problems after installation

I've tried Ubuntu, Xubuntu, & Lubuntu. The latter two did not even make it to the install screen, however the former managed to install without a hitch. All were the latest versions. As stated in the title, I have a Gateway GT5228 with all the stock hardware, except for an extra hdd & disc drive. That's a dual core AMD Athlon X2 4200+ & a Nvidia GeForce 6100. Ubuntu makes it to the desktop and then freezes. I can't bring up the command window or anything, all I can do at that point is hold down the power button and try something else.   I'm curious if this is a common problem or if it's something with my computer. I can run windows 7 Ultimate 64 bit just fine & Win 8 & Win xp. Any info would be appreciated, I haven't found much on my specific model having problems with Ubuntu.  thanks!


How to check when statistics was last executed?

We've been having a number of issues with our indexes lately which our DBA team has attributed to statistics not having been run recently. This has made me wonder - how can I check if statistics have been recently updated via SQL Management Studio?  I apologize if this question isn't explaining this very well - I've only been introduced to statistics until now and prior to this would look to indexes whenever I've had performance related issues.  Edit:  I'm using the following but receiving a syntax error:  use *databasename* exec sp_autostats *schema.tablename*   The error I'm receiving is:  Msg 102, Level 15, State 1, Line 2 Incorrect syntax near '.'.   Why is this?


Book about a boy who joins secret society that protects the timelines. They time travel through sleep

It has been some years (before 2009?) since I've read this book. The story starts off with this boy [teens] who can sleep anywhere, even with his eyes open, and can do this on cue! This secret company find him and tells him about this place with other kids. They tell him he has been selected for this group that protects the timelines or something. I not sure how but they do this through stripping off all their clothes and going to sleep. When they wake in "dream" they have proper clothes on for that time period, and have something they are looking for that doesn't belong or something.   He goes on this journey with two friends he makes. This girl who at some point gets her hair braided by these tribal women with amazing hair. In the end they strip again and fly to this secret place they been trying to find which is the root of this disturbance in time or something. I seem to recall this real meta guy comes and takes him to the beginning of time and they end up taking this whole civilization there to save them all and save time.  In the end he wake up and meets the head guy and I forget everything else but that's where it ends.   This story is part of a series of some kind and this was the 1st book. From my memory it was real big (over 500 pages) and had this snake on the cover in a circle of sorts (that's what caught my eye to pick it up) and I swear it had Dream in the name 1st. I don't remember it having any awards but I thought it was really good.


Identifying selected feature using PyQGIS?

If I select a feature and run self.iface.actionIdentify().trigger() it will open the identify window but won't open the selected feature's data, how can I make it open the data of the selected feature?


How does a desktop charging station decide its output voltage?

I have this charger:  It supports QC3.0 and has: Output USB-A DC 3.6-6.5V/9V/12V/14.5V/16V3A/19V/20V3.5A QC3.0 USB-C DC 5V/9V/12V/15V/18V/20V3A  i connected a 2pin 12v computer fan to one of its USB-A port and the multi-meter suggested that the charger is outputting 30v obviously, a 2 pin fan does not support any kind of charging protocol, why did it still getting a > 5v voltage? How does the charger decide its output voltage for old device like old iphones(5V 1A), or when D+/D- pins are not connected(like my fan)? I plan to drive a WS2812B RGB LEDs Strip (60 leds, DC 5V, 18W) with the charger, how can i control its output voltage? Update: i think its defaulting at 20V output on USB-A, while everyone is suggesting that the default output should 5V when there is not any negotiation not connected to any device  connected to a fan  connected to arduino


History of "different from", "different to", "different than"

Somehow I got the impression that "different to" (almost entirely unknown in America) is a locution that originated in the 20th century, and that "different from" is far older. Then I found "different to" in one of the Sherlock Holmes stories by Arthur Conan Doyle. Some (most?) of those were written in the 19th century, and all were written by a native speaker of English who reached adulthood before 1880. "Different than" seems like a far more recent locution, but again I don't know its history. I dislike "different than", but I've noticed that its use makes possible some efficient expressions that might not be possible otherwise (right now I can't remember any).   Is "different to" in fact a far newer locution than "different from"? If so, did it originate in the 19th century? Has "different from" become non-standard usage in some places where the vernacular language is English?


I have been reading about the working of transformers at "no load" condition, that is when no load is connected to secondary side of the transformer. I don't understand why the transformer still draws a little current called "no load current." I read about it on different websites and in books and found that it is to set up magnetic flux in the system.  Does drawing the current make the system stable or anything else, mustn't there be a requirement just like water has to go down a hill so that it can lower its potential energy?


Explain why the NodeMCU auto-program circuit would be useful

I'm looking at the  but could not understand why it is there at all.    From my point of view, this circuit enables open-collector outputs, but makes programming dependent on the time between switching the DTR and RTS pins being smaller than the ESP goes from reset to sampling the GPIO0 level.  Another reason I could imagine was to avoid invalid startup/connection resets, but I can't see why proper pulling couldn't fix this.  Is there any reasoning I couldn't see from my analysis? Why isn't DTR/CTS connected directly with one transistor on each line? Why controlling each line directly (and thus allowing to switch GPIO0 low before resetting without glitches) wouldn't be better?  EDIT: while the question is about the same structure shown in , I understand it's function and know it's not a flip-flop (no need to redraw it). What I'd like to do is know why was it chosen instead of a much simpler open collector configuration like the one below, specially since this one doesn't generate a glitch in the transition between the two programming states (from reset to/from GPIO0=0).


How to check if value is in range of cells?

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


Why is the identity element included in the definition of a group?

Why does definition of a group $G$ always include the requirement that there is identity element $e \in G$ such that for all $a \in G$, $ae=ea=a$, when I prove the existence of such an identity with only the inverse element $a$?


A word for someone who does something for personal gain or financial reward?

What do you call somebody that does something for someone else for money or other personal gain and not because they want to?  For example, when someone votes for a candidate in an election because they get paid to do so, and not because that's the candidate they want.     He only voted for the candidate because he was paid to do so. He's just a ________.


After using ElementaryOS I am back on Ubuntu. In eOS one of the features are "no desktop icons" and "no right-click option on desktop" and i prefer that setting, its simple and lightweight and I don't use the desktop anymore, only for wallpapers.  How can I completely deactivate the desktop in Ubuntu 14.10 (like eOS)?


Uninstall old kernel Fedora 28 Workstation

I have the below kernels installed on my machine:  [rajiviyer@rajiv-pc dnf]$ sudo dnf list installed kernel Installed Packages kernel.x86_64                     4.16.3-301.fc28                      @anaconda kernel.x86_64                     4.18.14-200.fc28                     @updates  [rajiviyer@rajiv-pc dnf]$    New Kernel: 4.18.14-200.fc28  Old Kernel: 4.16.3-301.fc28  Below is the list of dependencies for the Old Kernel: 4.16.3-301.fc28  [rajiviyer@rajiv-pc dnf]$ sudo dnf list installed kernel*4.16.3-301.fc28.x86_64 Installed Packages kernel.x86_64                            4.16.3-301.fc28               @anaconda kernel-core.x86_64                       4.16.3-301.fc28               @anaconda kernel-modules.x86_64                    4.16.3-301.fc28               @anaconda kernel-modules-extra.x86_64              4.16.3-301.fc28               @anaconda [rajiviyer@rajiv-pc dnf]$    I got a reference article which shows the steps to remove old kernel:   Kindly advice if I should proceed with the steps laid down in the article.  OR  Any GUI tool to remove kernel?  Post kernel removal what are post tasks need to be carried out? For e.g Updating GRUB


How to set nomodeset GRUB2 before I've installed Ubuntu

When I hit e this is what I see   where do I place nomodeset


How to restore Mac Normal boot (Login before booting up to macOS)

After Reinstall macOS Due to Blinking Folder into question mark, something changed I boot it up and asks me to login first before booting up I tried to Reset NVRAM/PRAM but it won't make changes Is it kind of the exploited Version?


I got a logo in blender and im trying to rotate it 360 degrees. But when i rotated it i realized it isnt centered. I found out that the logo got some invisible edge or something, because when i do "Origin to Geometry" it still isnt in the middle. (Sry for my bad english + second project in blender)


I am living in UK and using money earned outside of UK

I am currently a UK resident on spouse visa. I still have got my home country's bank account. I also have debit card linked to the account in my home country bank account. Can I use/spend this money in UK. Do I need to declare this in any tax form? or pay any taxes?


Incorrect grammar versus different dialects

My girlfriend, someone from southern New Jersey, constantly says phrases like "I'm done my homework" or "I'm done my dinner."  I try to correct her and say, "I'm done with my homework" or "I'm done with my dinner," but she insists this is what she has always said.  Is her grammar just plain incorrect, or is this allowed if she actually has a different dialect where everyone in the region says the same thing?


Is it possible to make a non-inverting amplifier with positive feedback?

The 'classic' non-inverting amplifier configuration uses negative feedback. What happens when the + and - terminals are switched? Based on my pencil-and-paper analysis and a Circuitlab simulation, it seems that the result is the same. Is this correct? Can we make a non-inverting amplifier with positive feedback?  Derivation for the positive feedback non-inverting amplifier: I assume that input impedance is infinite, output impedance is zero, and the output voltage is given by   $$ V_{out} = A(V^{+} - V^{-}) $$  Now using the voltage divider equation,   $$ V^{+} = V_{out} \frac{R_b}{R_a+R_b} $$  and for the negative terminal, we have  $$ V^{-} = V_{in} $$   Substituting into the equation for the output voltage,  $$ V_{out} = A(V^{+} - V^{-}) = AV_{out} \frac{R_b}{R_a + R_b} - AV_{in} $$  $$ V_{out}(1 - A \frac{R_b}{R_a + R_b}) = -AV_{in} $$  $$ V_{out} =  \frac{-AV_{in}}{1 - A \frac{R_b}{R_a + R_b}}$$  If the input frequency is relatively low, and both resistors are of a similar order of magnitude, then   $$ A \frac{R_b}{R_a + R_b} >> 1$$  $$ V_{out} \approx \frac{-AV_{in}}{ - A \frac{R_b}{R_a + R_b}} =  V_{in} \frac{Ra + R_b}{R_b} $$  Which is the formula commonly given for the output of the classic non-inverting amplifier. So is there any difference between these two circuits? If so, where does my analysis fail? What is a more accurate way of analyzing the positive feedback circuit presented below?     EDIT: As suggested by Jasen, the positive feedback circuit I posted is a Schmitt Trigger. The Wikipedia article on  explains it fairly well. It turns out that they key to analyzing it is to solve for the voltages at the input terminals and then treat the Op-Amp as a comparator. That is, find equations for V+ and V-, and then ask the question "When does V+ > V- hold?"


how to: Please sudo, do _not_ setup any environment, especially $SUDO_USER?

I want to start a process as another uid and it should not need any information from $(env), so I strip the environment prior to the sudo -u powerlessuser /bin/processCmd, that is I run this  env -i sudo -u powerlessuser /bin/processCmd   it turns out sudo thinks it is necessary to repopulate the environment, which I would like to ask it not to do. There is for instance $SUDO_USER set which even tells the powerlessuser's /bin/processCmd about me(tm) that called the command, which I find very indiscrete. Any help?  It is as I figured also possible to use env -i stripping after the sudo, i.e. do this:  sudo -u powerlessuser /usr/bin/env -i /bin/processCmd   which solves the problem somewhat, yet I would really like to know if there is a way to make sudo not add any information in the first place, I browsed  in which I found documentation that sudo adds environment and which, but no help how to make sudo not do that  @terdon♦: I want all environment variables cleaned that are not necessary. I am unable to tell which environmental variables are necessary but just to stick to the question, I have not found the reason why $SUDO_USER would be needed by a process to be called as an unpriveledged user. Therefore I would be satisfied to know how to tell sudo not to leak SUDO_USER  Update - xy-problem issue  As much as I am very interested in avoiding anything of the kind of a xy-problem, I fear it is not the case here. That is because, I do not have actually a different problem as the one stated in the question, namely that searching a way to make sudo not do something, which I can reasonably expect: Sudo get an cleaned up environment and should at best not add stuff to it, i.e. $SUDO_USER. For this reason I am rather very convinced not to have any other problem, since I have already a cure to that issue that sudo leaves me with, i.e. I can do:  sudo -u powerlessuser /usr/bin/env -i /bin/processCmd   which "cleans up after sudo", so in no way is my problem something else, because using the subsequent env -i solved any problem there. The only thing I ask is for knowing if there would have been indeed a way like  sudo --empty-env which then would spawn the new process with an emptied environment, one that at least would not tell $SUDO_USER which uid ran the original sudo.   For all that showed interest in helping me with this question, I like to thank them! I also leave some time, maybe there is such a --empty-env switch possibility. If not maybe somebody that is inside of sudo can tell, i.e. with reference to the sources that such a task is impossible, as sudo cannot but put that undesired $SUDO_USER inside.  Again no xy-problem, for the fact, that it is not really a problem to start with, i.e I do not suffer from the shortcomings of sudo here, as it is solved by a subsequent env -i, which in "unix philosophy" is the one thing that env -i does well, i.e. clean the environment. I should maybe not even have expected any reasonable behavior from sudo there, as sudo has a different one-purpose, which is not concerned about environment variables leaking. Even though, the fact that sudo does offer some flags relating to environment variables misleads into thinking it would deal with environment variables well.


Do "twice as high xxxxx as" , "twice as high" and "twice higher" mean the same thing?

What do the following sentences actually mean?  Are they the same in meaning?        The cost of living is twice as high in New York as it is in Tokyo.   The cost of living in New York is twice as high in Tokyo.   The cost of living in New York is twice higher than in Tokyo.   The cost of living in New York is two times higher than in Tokyo.      If they have the same meaning, then can I actually use them as a basis for composing other sentences having the same meanings? Such as:     1a. Your child is a hundred times as adorable as your pet dog.   1b. Your child is a hundred times adorable than your pet dog.      2a. Her room is twice as large as mine.   2b. Her room is twice larger than mine.


I have a document (Texstudio in OSX) written using the LatexBangla package (XeLaTex system). But I am unable incorporate a bibliography in English written using biblatex (biber). The minimal code is given below. \documentclass[11pt,a4paper,onesided, notitlepage]{article} %\usepackage[english]{babel} \usepackage[banglamainfont=Kalpurush, banglattfont=Siyam Rupali ]{latexbangla} \usepackage[backend=biber,style=alphabetic,sorting=nyt, language=english,autolang=other]{biblatex} \begin{document} Hello  \end{document}  I get the following error - line 7: Package etoolbox Error: Toggle 'blx@lang@captions@bengali' undefined. \begin{document} : 'babel/polyglossia' detected but 'csquotes' missing. : Unused global option(s): [onesided]. : Language 'bengali' not supported. : No file bengali_test.bbl. : There were undefined references. : Please (re)run Biber on the file:(biblatex) bengali_test(biblatex) and rerun LaTeX afterwards.


This question comes about because I usually always spell the word incorrectly and the spell checker underlines in red the word: compatible.  In my head, I always want to spell it compatable, and my logic is as follows.  First, look at a definition:     Definition of compatible   a. - Capable of existing in harmony; congruous; suitable; not repugnant; -- usually followed by with.    There's a few words in there that make sense to my brain. Capable and suitable both have the -able suffix, because they can do something.  The root of the suffix is pretty self-explanatory.  Able, suggestive of the ability to do whatever it is that the suffix is appended to.  Examples of words that make sense to me are:    persuadable: the ability, or able-ness to be persuaded placable: [...] to be placed unappeasable: the inability, or unable-ness to be appeased   Other words of which the spellings are confusing to me: accessible, compatible, fallible, immersible  Why the -ible, and not -able when the end result seems to be expressing the same able-ness?  To me, they should be spelled accessable, compatable, fallable, immersable.  What's the root of -ible being used and not -able?


I'm new to RMI, and was following the Oracle's RMI tutorial code at  and wrote something similar.  My code was working correctly, everything fine. But I didn't touch the code, and today after 3 weeks when I just came and tried to run it again , surprisingly it was not running anymore, and throws the following exception: (of course I did start rmiregistry).   How can I fix the problem? I am running Java 1.8.0.60 and use eclipse.  SOLUTION: I should have run rmiregistry in the bin folder (or probably set classpath with other ways).  Server exception: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:      java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:      java.lang.ClassNotFoundException: test.Hello java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:      java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:      java.lang.ClassNotFoundException: test.Hello ... continued ...   Here is the code for HelloServer:  package test;  import java.rmi.registry.LocateRegistry; import java.rmi.registry.Registry; import java.rmi.server.UnicastRemoteObject;  public class HelloServer implements Hello {      public HelloServer() {}      public String pollServer() {         String data= EchoServerRMI.queuePoll();         System.out.println("polling test"+data);         return data; //      return "1";     }      public static void main(String args[]) {          try {             HelloServer obj = new HelloServer();             Hello stub = (Hello) UnicastRemoteObject.exportObject(obj, 0);              // Bind the remote object's stub in the registry             Registry registry = LocateRegistry.getRegistry();             registry.bind("Hello", stub);             System.err.println("Server ready");         } catch (Exception e) {             System.err.println("Server exception: " + e.toString());             e.printStackTrace();         }     } }   And here is the code for Hello class:  package test;  import java.rmi.*;  public interface Hello extends Remote {     String pollServer() throws RemoteException; }


Is there an operator for 'contained in set or subset or subset of subset' and so on?

Assume I have a set, the elements of which may be sets, some of which may have sets as elements in turn, and so on. Is there an operator or a convenient way to express this relationship?


java.lang.NullPointerException with EditText Android Studio

I have resolved this before but I can't remember what I did. Basically its a simple EditText and finding it's view by id but i get the error messagejava.lang.NullPointerException when running the app.  public class MainActivity extends Activity {  CallbackManager callbackManager; public static final String SECRET_KEY = "65EB1D3A-F8D8-D6DC-FF21-E111F9409600"; public static final String APP_ID = "F5931D23-2392-1B65-FF65-BC4256BB9300"; RegisterAccount register; EditText mName = (EditText) findViewById(R.id.userName); EditText mEmail = (EditText) findViewById(R.id.userEmail); EditText mPassword = (EditText) findViewById(R.id.userPassword); EditText mConfirmPassword = (EditText) findViewById(R.id.userConfirmPassword);  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     FacebookSdk.sdkInitialize(this.getApplicationContext());     requestWindowFeature(Window.FEATURE_NO_TITLE);     getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,             WindowManager.LayoutParams.FLAG_FULLSCREEN);      setContentView(R.layout.activity_main);     Backendless.initApp(MainActivity.this, APP_ID, SECRET_KEY, "v1");      BackendlessUser user = new BackendlessUser();     user.setEmail(mEmail.getText().toString());     user.setPassword(mPassword.getText().toString());      Backendless.UserService.register(user, new AsyncCallback<BackendlessUser>() {         @Override         public void handleResponse(BackendlessUser backendlessUser) {              Intent logIntent = new Intent(MainActivity.this, ContentActivity.class);             logIntent.putExtra("Name", mEmail.getText().toString());             startActivity(logIntent);         }          @Override         public void handleFault(BackendlessFault backendlessFault) {             // On failure         }   });


What happens to photons after they hit objects?

If I am not wrong when light hits for example white wall most of the photons are absorbed and transformed into heat and few of the photons at certain wavelength are reflected from the object. So white wall reflects photons at wavelength corresponding to white color so we can see it.  1.Can someone clarify if it is correct?  2.What happens if that photons reflected from white wall hit another white wall (are they reflected once? If that so can they be reflected forever?)  3.What happens when I "shoot" photons of certain wavelength into object which color corresponds to that photons wavelength e.g. Blue light into blue wall


Convert a value into a "Binary Number" in a shell script

I know of bc:  $> var="304" $> echo "obase=2; $var" | bc 100110000   Could it be done in shell (no external call)?  This question:  Asks how to convert FROM binary, not TO a binary number.  The answers there deal either with binary byte (as opposed to binary number, i.e.: a base-2 number) using xxd, or some other external tool. So, no, this question is not a duplicate of that.


Draw integers independently & uniformly at random from 1 to $N$ using fair d6?

I wish to draw integers from 1 to some specific $N$ by rolling some number of fair six-sided dice (d6). A good answer will explain why its method produces uniform and independent integers.  As an illustrative example, it would be helpful to explain how a solution works for the case of $N=150$.  Furthermore, I wish for the procedure to be as efficient as possible: roll the least number of d6 on average for each number generated.  Conversions from  to decimal are permissible.    .


Did Professors at Hogwarts Take a Salary?

Would the professors of Hogwarts be paid a salary for their teaching?  There's obviously Gringot's where the wizarding world (at least in the UK) would store their riches. I seem to recall there being mention of folks at the Ministry of Magic being paid (I think Ron's dad mentions something about his salary at one point in the movies).  But there's no real mention, as far as I know, of Hogwart's professors being paid, I would assume they'd just live at the school and have their needs met through the 'government'.  It also begs the question of would they be paid in the currency of the local 'muggle world'? Harry visits his parent's vault shortly before heading to Hogwarts and takes out a bunch of galleons to pay his tuition. In the muggle world, this seems like it would be a strange interaction when buying something, ex. paying for groceries using some galleons.


What happens if I don't use & at the end of a nohup command?

What's the difference between nohup foocommand and nohup foocommand &?   I understand that & marks the task/job/process as running in the background but does that make it more resilient than it would otherwise be?   What happens in both scenarios if my SSH session timeouts or if I get disconnected?


How to resolve java.lang.NoSuchMethodError

I have a project that I can run correctly from within Eclipse, but running the standalone jar gives me the java.lang.NoSuchMethodError for a class at runtime.   I unpacked the jar file and can see the class file in one library file in jar and I do see the method defined in the class. The exception is not about class not found, but just can't find the method in the class.   Could not find any helpful information on the internet for how to solve it.


Use awk to list all values seen in a column


New ways of ending the question -- solved by myself, solved by comment

OK, for me it is pretty obvious, but Stack Exchange still does not have such features:  I asked a question and a week later I found an answer -- I would like to edit the question to add section "solution" and mark question as solved (not closed though) I asked a question, and somebody commented:  hey, why don't you use foo and bar?    which appears to be a perfect solution -- thus I would like to mark a COMMENT as THE answer; it would be nice, if the Stack Exchange engine automagically ripped off that comment and put it as an answer (reply).


Are there Fingerprint taking processes in Polish airports for Schengen Visa Holders at the time of entry to the country?


I want a book in general topology with many interesting and hard exercises. I mean a book with topics the same as Munkres  but with challenging questions to improve my problem solving ability.


Are there any known MD5 hashes that can´t occure, no matter what (finite) input is taken?   Thanks


I am looking for a way to convert an int to a string of a given length. If the representation of the number is shorter, it should be zero-filled.  I.e., what I'd like to see:  snprintf(buffer, 3, "%d", 5); -> 005 snprintf(buffer, 2, "%d", 55); -> 55   Actually, snprintf(buffer, 3, "%d", 5); just return 5 in string.  Is there a simple way to do this ?


Illustrator - Delete everything that's outside Objects

How do I delete all the unnecessary white shapes, only keep the ones on the logo itself.


Aligning several \begin{align} blocks in LaTeX

Just a quick question regarding aligning equations in LaTeX. Basically, this is a snippet of my source code:  \begin{align*}   dU&=\partial Q - \partial W \\   \partial Q &= dU + \partial W \end{align*} Since $U_E$ was already calculated, $U_A$ can be calculated using equation (1.1) as well: \begin{align*}   U_A&=\frac{3}{2}PV \\   U_A&=\frac{3}{2}*10^5*10^{-3}\\   U_A&=150J \end{align*}   Now, the problem I'm facing is that the first align* tag is not aligned with the second one, I mean the equations are shifted. I'm not 100% sure why this happens or how to fix this.


(Enderton set theory) Hartog's theorem and cardinal numbers

Assume that A is a set and define (as in Hartogs' theorem) $\alpha$ to be the set of ordinals dominated by A. Show that (i) $\alpha$  is a cardinal number, (ii) card A < $\alpha$ , and (iii) $\alpha$  is the least cardinal greater than card A. This question is from Enderton textbook. Any help would be appreciated! Edit: I have tried the following to think about (i), (ii) and (iii), although I don't think it's a meaningful progress. (i) $\alpha$ has to be an initial ordinal number for it to be a cardinal number. How do we show if $\alpha$ is an initial ordinal number? (ii) $\alpha$ is equinumerous to card($\alpha$). Since $\alpha$ is the set of ordinals dominated by A, $card (\alpha)\leq card A$. I feel like this problem shouldn't be hard, but I'm stuck for some reason. I would appreciate any help on this problem and any suggestion as to how I could improve on thinking about those problems. (I don't think my understanding of axiom of choice is thorough - how would you advise me to study the axiom of choice?)


Do light particles come in different sizes?

Do light particles come in different sizes if it makes sense to even think about them that way?


Why do all of Riley's emotions in Inside Out look different?

Ever since I first watched Inside Out, I've always wondered why Riley's emotions all had such different designs. When it shows her mom's, they all have similar hair and glasses and they're all female, her dad's all have suits and mustaches and they're all male, and the curly headed kid's all have curly hair and hats and were all boys. Riley's emotions all have very different appearances and different genders, and I never really understood why that was.I don't know if it's just to make Riley's character stand out, or if it was just part of the design process, but I was always just curious.


Python testing tool like Behat in the PHP

I am trying to test a web-application, using python, I am new in python so don't know much Python testing tools, i have written tests in Selenium/Pink/Behat in the PHP world, Now i have to use python for Behavior-Driven-Development (BDD), I have been looked Google, but I couldn't really get a definitive answer. can any one please suggest me best python testing tool, like Behat.  Thanks in Advance


How to send array with CURL? Should I `urlencode` it?

When I assign an array of data to be POSTed as a cURL option (via CURLOPT_POSTFIELDS), do I need to urlencode that data first or will that be taken care of?


How may I return a const reference to an object from a method?

public Item getItem(ulong itemId) {     Item item = items[itemId]     return item; }   Now the problem is: the callee of getItem must be able to retrieve information that item holds; but not modify it.  Sorry, but I know C++ better than C#... I'm afraid I must fall back to C++ for a teeny tiny while just to make myself clear what I'm trying to achieve... So this is what I'd do in C++ in this situation:  const Item& getItem(unsigned long itemId) {     const Item& item = items[itemId];     return item; }   Very well - now whoever called getItem may call getters on item, but not setters.  I need to achieve a similar result in C#... is it possible?


Boolean intersect behaves sometimes unpredictably

I'm having some weird and mostly unreproducable error concerning the boolean-intersect modifier. In rare cases, it does not cut objA along the edge of objB but rather along the contour. See the following pictures for clearification:   The modifier on the heel behaves as expected when intersecting the plane, but the one on the forefoot sometimes yields these strange results.    Does someone have an idea why that behaviour occurs? Thanks!


How to create a freeze Header/column table with dynamic data in visualforce

I have to create a table which gets data dynamically. Its rows and columns are populated dynamically and I am using Pageblocktable. Now I have to freeze its header and first column. Can anyone help me.  Thank you Suja


I get This error when I try to install MySQL on ubuntu:  sudo apt-get install mysql-server [sudo] password for xxxxx:   Reading package lists...  Done Building dependency tree        Reading state information... Done E: Unable to locate package mysql-server   How can I fix this?


How do I fit a constrained regression in R so that coefficients total = 1?

I see a similar constrained regression here:    but my requirement is slightly different. I need the coefficients to add up to 1. Specifically I am regressing the returns of 1 foreign exchange series against 3 other foreign exchange series, so that investors may replace their exposure to that series with a combination of exposure to the other 3, but their cash outlay must not change, and preferably (but this is not mandatory), the coefficients should be positive.   I have tried to search for constrained regression in R and Google but with little luck.


How to move files between Ubuntu and iPhone

I recently got an iPhone 6s. Is there a way to transfer files (music, photos, PDF, or really anything actually) between Ubuntu and the phone? It should not involve syncing via an internet service, as I may have the need to transfer large or private files. Also, I do not want to jailbreak the device.  There are a few results when searching for this on Google, but none seems very up to date.


Unable to access external hard disk "unknown filesystem type 'exfat'"

Error mounting systems managed device /dev/sdb1: Command-line mount"/mnt/5617-A6EF" exited with non-zero exit status 32:mount:mnt/5617-A6EF:unknown filesystem type 'exfat'.   How to fix this?


I'm trying to figure out how to set a default host for my nginx installation. I found this article in the nginx Wiki:    Unfortunately, this doesn’t work. After restarting I get this:  Restarting nginx: nginx: [emerg] unknown directive "http" in /etc/nginx/sites-enabled/catchall:1 nginx: configuration file /etc/nginx/nginx.conf test failed   After removing the http directive I get this:  Restarting nginx: nginx: [emerg] unknown log format "main" in /etc/nginx/sites-enabled/catchall:7 nginx: configuration file /etc/nginx/nginx.conf test failed   I’m on Ubuntu 10.04.3 where I’m using the official nginx PPA. Version 1.0.9 of nginx is running.


So I have this piece of Java code:  if (e1.getNodeName().contains("column")) {     String temp_type = "";     String temp_index = "";     String name = "";     String format = "";     int index = 0;     DataType type = null;      try {         name = e1.getElementsByTagName("name").item(0).getTextContent();         System.out.println("Name: " + name);     } catch (NullPointerException e) {         System.out.println("No name");     }      try {         temp_index = e1.getAttributes().getNamedItem("index").getNodeValue();         index = Integer.parseInt(temp_index);         System.out.println("Index: " + index);     } catch (NullPointerException e) {         System.out.println("No index");     }      try {         temp_type = e1.getElementsByTagName("type").item(0).getTextContent();         try {             type= DataType.typeOf(temp_type);         } catch (UnknownDataTypeException e) {             System.out.println("Unknown Data Type");         }         System.out.println("Type: " + type);     } catch (NullPointerException e) {         System.out.println("No type");     }      try {         format = e1.getAttributes().getNamedItem("format").getNodeValue();         System.out.println("Format: " + format);     } catch (NullPointerException e) {         System.out.println("No format");     }   I am reading an XML file by implementing a DOM parser. I have a sample XML file and ever entry DOES NOT contain all of the following values (name is missing for the first entry). When I run this piece of code, everything prints out perfectly and I am able to handle the errors exactly how I want to.   My next step is to use each of these values (name, index, DataType, format) to create a Person object which I have defined in a previous class. I thus having the following piece of code to create a Person object and add it to an ArrayList (personList):  Person c = new Person(name, index, type, format); personList.add(c);   Those two lines above give me a NullPointerException, even though I handle the thrown errors and I define initial values for my instance variables name, format, index and type at the beginning of the code.  Why doesn't Java see that I have already dealt with those errors and allow me to properly create a Person object?  I deeply appreciate all help.   Below is my Person class:  public class Person {     public String name;     public int index;     public DataType dataType;     public String dateFormat;      public Person(String name, int index, DataType dataType, String dateFormat) {         this.name = name;         this.index = index;         this.dataType = dataType;         this.dateFormat = dateFormat;     }      public String getName() {         return name;     }      public int getIndex() {         return index;     }      public DataType getDataType() {         return dataType;     }      public String getDateFormat() {         return dateFormat;     }     enter code here  }


MEDIATEK Corp. MT7630e 802.11bgn: recipe for target 'dkms' failed

lspci -knn | grep Net -A3 03:00.0 Network controller [0280]: MEDIATEK Corp. MT7630e 802.11bgn Wireless Network Adapter [14c3:7630]     Subsystem: Foxconn International, Inc. MT7630e 802.11bgn Wireless Network Adapter [105b:e074]     Kernel modules: wl 04:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTL8411 PCI Express Card Reader [10ec:5289] (rev 01)   UPDATE:  ~/MT7630E$ sudo make dkms cp -v firmware/*/* /lib/firmware/ 'firmware/BT/mt76x0.bin' -> '/lib/firmware/mt76x0.bin' 'firmware/Wi-FI/MT7650E234.bin' -> '/lib/firmware/MT7650E234.bin' cp -R . /usr/src/mt7630e-`sed -n 's/^[[:blank:]]*PACKAGE_VERSION=\([^[:blank:]]*\).*/\1/p' dkms.conf` dkms add -m mt7630e -v `sed -n 's/^[[:blank:]]*PACKAGE_VERSION=\([^[:blank:]]*\).*/\1/p' dkms.conf` Error! DKMS tree already contains: mt7630e-2.1.0 You cannot add the same module/version combo more than once. Makefile:29: recipe for target 'dkms' failed make: *** [dkms] Error 3


namespace ClientApp {     [Service(Exported = false)]     class RegistrationIntentService : IntentService     {         static object locker = new object();          public RegistrationIntentService() :  base("RegistrationIntentService") { }   In the snippet above, the constructor extends a base("RegistrationIntentService"), what is this doing? I found this example at:    Does it mean the contructor is the same as the RegistrationIntentService constructor?


How do i save query result as .csv file?

Following is my sql query to get data from mysql database. So how do i save it as .csv file ?   <?php $sqlagentdetails = "select * from users WHERE company_name != ''"; $rowresult = mysql_query($sqlagentdetails);  while($row = mysql_fetch_array($rowresult, MYSQL_ASSOC)){     $pc1 = $row['pc1'];     $pc2 = $row['pc2'];     $pc3 = $row['pc3'];     $pc4 = $row['pc4'];                           $emailAgent = $row['user_email'];                           $user_id = $row['id'];  $myQuery =  mysql_query("  SELECT *     FROM user_property upr    WHERE (postcode = '$pc1' OR          postcode = '$pc2' OR          postcode = '$pc3' OR          postcode = '$pc4') AND          datediff(CURDATE(), upr.creation_date) <= 7 AND          NOT EXISTS(SELECT ofr.property_id                        FROM offers ofr                       WHERE ofr.property_id = upr.property_id AND                            ofr.agent_id IN(SELECT id                                               FROM users                                              WHERE company_name !=''                                           )                    ) ORDER BY property_id DESC"); $num =  mysql_num_rows($myQuery); while($row = mysql_fetch_array($myQuery)){        /// data is showing here............      }// second while statement  }// first while statement ?>   It's showing following data column  Email | Pcode | Quote | type | House | type | B | Ba | P | Value | Date |  Listed | Status


How can I install Skype on Ubuntu 14.04 with synaptic? I don't want to download from the site


Long display name with no spaces breaks design of review history pages

See for yourself:        Name with a space doesn't cause any problem as far as I could see.


Dissolve without removing interior lines in ArcMap?

I'm fairly new to GIS and I'm having an issue that I hope someone can help me resolve?  Basically, what I'm trying to do is merge features based on a single attribute so that my table no longer displays the duplicates and the features are merged/grouped on screen. Other than going through my attribute table and manually selecting the features before clicking 'merge', the only other way that I could think to do this would be to use 'dissolve'. However, using this tool causes the features that are touching or overlapping to become one entity, which is the opposite to what I want to achieve.  In short, I wish to keep my features as separate entities that are grouped/merged together based on a single attribute whilst removing duplicates from my attribute table - is this possible?  Also, it's worth noting that I have 1000's of features to do this with, so I'm looking for an automated method of some kind?


In the attached picture, that the model is in the center of the point. I want to change from pivot point to point, where I want to picture it. In Maya 2017 Student version works like this, when it is possible to change with the D keypad.  Blender is so possible?  Thank you in advance for your help!


proving convergence of $a_{n+1}=1+\frac{1}{1+a_{n}}$

$a_1=1.$ $a_{n+1}=1+\frac{1}{1+a_{n}}$  Prove that the sequence is convergent. I'm trying to prove the convergence of this sequence but having trouble. At first I thought this might be a monotone sequence since then I can try monotone convergence theorem to prove its convergence. But after checking some terms, I realized it seemed the sequence is oscillating. So I'm not sure how to prove the convergence of this sequence. Thanks.


Where to put coding a validation script for store?

I am pretty new using WordPress and was asked to validate the number of items in the cart for an eCommerce site that lets you "make a pack" in which you have several steps, step 1 is a page in which you select the box, this doesn't need validation but the next 4 steps do, each step is a new page and each has a different amount of the item that you need to select, what I need is to either disable the hyperlink that says "Next step" until you select the correct amount of items for each step or just display a message when you click with the incorrect amount  Now my question is not code itself but where to put it in WordPress, I checked everything in the WordPress admin part of the site and on the hosting site but can't find where I am supposed to code the validation for each page.


Ideals in $F[x]$ and Euclidean domains are generated by any element of minimal degree

Let's start with a definition:     Definition: Let $F$ be a field, $I$ a nonzero ideal in $F[x]$, and $g(x)$ an element of $F[x]$. Then, $I= \langle g(x)\rangle$ if and only if $g(x)$ is a nonzero polynomial of minimum degree in $I$.   Now it gets completely foggy what is meant with "minimum degree".I constantly come across the "minimal polynomial". This seems to be linked, but it seems strange that there is a division here.   Could someone give a pointer to what the second line actually means. Maybe some example or diagram (if possible) would help a lot here.


Within a JavaScript function how do I know if I was invoked with new?

If I have function:  function Thing( name_of_thing ) {     this.name = name_of_thing; }   Is there a way to know if invoked by:  var my_thing = new Thing( 'Something' ); // result: { name: "Something" }   versus:  var my_thing = Thing( 'Something' ); // result: undefined


i have a problem with syntax in the align environment:  \documentclass[10pt,a4paper]{article} \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{pgfplots} \begin{document} \begin{alignat*}{4} P'_1(t)&=-\lambda P_1(t)+\lambda P_0(t)\\ \Leftrightarrow &&\qquad  P'_1(t)+\lambda P_1(t)&=\lambda e^{-\lambda t} && (2.6)\\ \Leftrightarrow &&  e^{\lambda t}P'_1(t)+\lambda e^{\lambda t}P_1(t)&=\lambda e^{\lambda t} e^{-\lambda t}=\lambda \\ \Leftrightarrow && \frac{d}{dt}(e^{\lambda t}P_1(t))&=e^{\lambda t}P'_1(t)+\lambda e^{\lambda t}P_1(t)=\lambda\\ \end{alignat*} \end{document}   I just want to have the first line exactly above the equation in the second line but the && commands are pulling the first line to the left. Is there any easy possibility to fix this?  Thank you


I am new to QGIS (ESRI shop at work). I am attemping to concatenate fields in the label expression  field1 = number field2 = number   label expression I tired but fails  str(field1) + " - " + str(field2)   it says its not valid. This would work in ArcMap... how is it different?


Prove that if $a_{2n} \rightarrow g$ and $a_{2n+1} \rightarrow g$ then $a_n \rightarrow g$

The problem is in the question:  Prove that if sequences $a_{2n} \rightarrow g$ and $a_{2n+1} \rightarrow g$ then $a_n \rightarrow g$.  I don't know how to prove that - it seems obvious when we look at the definition that for sufficiently large $n$ (let's say $n>N$) we have $|a_{2n}-g|$ and $|a_{2n+1}-g|$ less than any given $\epsilon$ and these  are all elements of $a_n$ when $n>N$ (even and odd terms). Does this need more formal proof?


Let X1, · · · , Xn be independent N(0, 1) and Let $u_4 = E[X^{4}_1]$ Im having problems in how to calculate the expected value. I know that $\sum X^{2}_1$ of a normal(0,1) becomes a chi squared with E(X) = 1. How can i calculate $u_4$?


fontspec error with Urdu in LuaLaTeX / XeLaTeX

This is my document with some Urdu text between English.       \documentclass[smallextended]{svjour3}      \usepackage{xltxtra}     \usepackage{fontspec}     \usepackage{polyglossia}     \setmainlanguage{english}     \setotherlanguage{urdu}     \newfontfamily\urdufont[Script=Arabic,Language=Urdu,Scale=1.5]{Jameel Noori Nastaleeq}       \begin{document}     \title{Title goes here}     \maketitle     \section{Introduction}     English text here \texturdu{ اردو ٹیکسٹ} English text here     \end{document}   When I compile with LuaLaTeX or XeLaTeX it gives the following error:  ! Undefined control sequence. <argument> \LaTeX3 error:  Erroneous variable \c__fontspec_shape_n_n_tl used! l.3530 \emfontdeclare{ \emshape, \eminnershape }  ?


What's the easiest way to automatically insert images in a figure environment without fiddling with them endlessly?

Yes, this has been asked before but I can't find an answer. I've been experimenting with LaTeX on overleaf for around 3 months and I still can't get the hang of inserting images. Just let me plonk that shit down, why do I have to add five different modifiers and fiddle for two hours with pixel measurements to make something just fit on the page properly. Is there any way to automatically resize images, everything I try to insert is too large, so it gets off or gets its own page, which looks terrible It's always in the wrong position too, never where I insert it in the source code? What am I missing? I don't think I've ever been this frustrated working with something before besides coding. I know this is more of a rant than a question. If I wanted to plonk stuff down I'd just use a word, but I wanna make it work. If it's just one image it's fine, but inserting 5 or more images shouldn't take hours, should it? If someone decides to answer this, thank you! I'm not really expecting an answer, I'll probably get banned for having violated some rule  I haven't read about because this is too ranty or something. Clarification: I just wanted to get it out, but let's say I'm starting with the basic: \begin{figure}     \centering     \includegraphics{images/image.jpg}     \caption{Caption}     \label{fig:my_label} \end{figure}  What do I have to do to accomplish these things: 1-I want the image to appear where I put it in the code, not on the next page. 2-The image should be as wide as a line of text. I tried doing this: \begin{figure}[h!]     \centering     \includegraphics[width=\textwidth]{Agrobacteria.PNG}     \caption{Genomen van \cite{tzfira_agrobacterium-mediated_2006}}     \label{fig:my_label} \end{figure}  And it worked, but only on this one picture, when I try to copy the code and place it somewhere else the image moves to the next page or section.


I want to add two Principled BSDF in one material to one as texture  and principles for logo only with transparency to control roughness.


Normally clicking on the badges/reputation/avatar image of the top-bar links to the info tab of the own profile.  Lately  also got the new top-bar but it links to the reputation tab of my profile. That can't be right, right?


How leave Jenkins running remotely on the server?

I am running as follows Jenkins on my server:  $> labes@labes-jenkins:~/jenkins$ java -jar jenkins-1.622.war   But when I unplug my machine the application of jenkins goes down, as I do to get the application running at the same end my SSH session?  Note: Jenkins has the jetty embedded server inside the .war artifact.


Why Rogue One name (and not something more appropriate)

I watched Episode 3½ (Rogue One) and cannot understand why the name is Rogue One? It is the name of stolen ship but is this ship so important to name the film? Nothing more important than this... "The Death Star" (for example) would be more clear and understandable name.


Interest Rate vs. Annual Percentage Yield (APY)

I'm curious as to what the difference between the Interest Rate and Annual Percentage Yield is.  For example: This Bank I was looking at offers 0.45% interest rate on savings account balances over $100,000. It also has an APY of 0.45% on balances >$100,000.  I'm not interested in opening a savings account with $100,000+ for 0.45% so I'm not looking for feedback on whether that's a good idea or not, I'm just curious as to when they numbers are different, and why. I know they can be different with government bonds, but I would like a simplified example.


Converting a geocentric latitude to a geodetic latitude

I'm working with a 3D model of the earth (WGS84).   The input to my problem is a geocentric lat-long. Is there an efficient way to convert this to a geodetic lat-long?  My initial attempt to solve this seems to work correctly: First, convert the geocentric lat-long back to it's corresponding point in 3D space. Then, feed that XYZ into a library function that returns the geodetic latitude.   It's straightforward, but the conversion from XYZ to geodetic lat-long is not cheap because it uses some fixed number of iterations to come up with a reasonably accurate result... I am looking for something that runs faster.  Given the geocentric latitude, is there a more efficient route I can take to get the corresponding geodetic latitude?


In information theory, specifically in information content, I am struggling to conceptualise what the unit of measurement actually is. I have read quite a few similar  and worked through the derivation in Probability Theory: The Logic of Science, E.T Jaynes but still struggling to piece together the information.   The part I am struggling with is why the information content takes the form.  $$ I_X(x) = log\biggl(\frac{1}{p_X(x)}\biggr)$$  From what I have read so far, the use of the logarithm function makes sense, but $\bigl(\frac{1}{p_X(x)}\bigr)$ is where I am stuck. In plain english, I understand this to mean the quantity of information transmitted, or level of surprise when some event occurs. But I don't follow why this would takes this form. One idea I have trying to confirm (unsuccessfully so far) is that if that if some event $E$ occurs with probability $P$, then the amount of information received when this event occurs could be considered as $1 - P$.   If this is true, while also satisfying the requirements outlined by Shannon, is information content defined as above due to the following?  $$ I_X(x) = log\bigl(1\bigr) - log\bigl(p_X(x)\bigr)$$ $$ I_X(x) = 0 - log\bigl(p_X(x)\bigr)$$  or  $$ I_X(x) = log\biggl(\frac{1}{p_X(x)}\biggr)$$  I'm not sure if this is just assumed as being obvious, or a coincidence, but I haven't yet found an explanation that formally describes information content in this way (i.e. why information is $\frac{1}{p_X(x)}$).


Dynamically change  on link click without reloading any content

TL;DR  What is the best way to change a page's <title> tag when a link is clicked but page content is not re-loaded (simply shown/hidden via CSS)? Some JavaScript, I would assume?    On this page () I have two methods for viewing individual magazines. Clicking on the magazine cover on the right completely re-loads the page with a query string (e.g. ?mag=1) appended to the URL and we have set the <title> tag to change then, but this was additional functionality we added via PHP. The framework's original method of changing content was simply to change shown/hidden content via CSS (basic JavaScript to add and remove an active class) by clicking on the left-hand tabs.  However, I would like for the page title to change when these left-hand tabs are clicked, also. The HTML code for the tabs is as follows:

Electric &amp; Hybrid Marine

Marine Catering

Marine Maintenance

Shipping Port

ALL TITLES

   And for their content:

   I tried investigating, and I think something needs to happen in the DOM, but my JavaScript knowledge is unfortunately, almost completely non-existent. Can anyone kindly help?  EDIT:  I've tried changing my  tags to the following, but this doesn't seem to do anything:  <a onclick="window.document.title='<?=$title?> | UKIP Media &amp; Events'" href="#" class="skip" gumby-goto="#top_of_page" gumby-offset="-60">   ($title is a PHP variable set on page load)  SECOND EDIT @MGA  My link now looks like so:     With this script at the bottom of the page:     But still nothing happens?


Is it possible to use QGIS to convert a vector that contains points/polygons into a csv file and, if yes, in which way?


How much can a power brick safely vary from what the device it's used with expects?  As an example, let's say I have a device that needs an AC=>DC power brick. The device expects 19V/1.58A, but the brick is missing. Now let's say I find a brick where the connector fits the device and is also 19V, but outputs 3.42A. How safe is this likely to be for the device? Will the device only draw the power it needs, or am I likely to blow a capacitor somewhere?  If that latter, this example the brick provides more than twice the current requested. How much closer would have I have to get to be reasonable? How much can voltage vary vs amps? Given different devices likely have more tolerances than others, is there a good rule of thumb to look for to know how much you cheat on matching power brick to device?  While the example does match a real situation, I'm also interested in the general case.


What configuration is required to render images in terminal?

I'm looking for a way to open an image in tty*  I have this Memory about hearing w3m can render images.  If I use w3m to open an image in a GUI it spawns a child window. This was the only way with my current settings to get it to show an image.  Is there a supported file list for w3m? I might have been trying to open an unsupported file type.  Is there some configuration in Ubuntu where I can permit or add the ability to draw images in terminal?  Is there a different command that can render an image in terminal?  I know this question has been asked a few times before but at least one had no solution and it was closed for being unclear; there were answers on other questions but they suggested using commands to spawn x-windows or they would use colored spaces to render the image.  The solution I'm looking for is something that can get pixel level access on a character block or that this is not possible [in Ubuntu 17.10 but it is possible in ...].  If the only available answer is to convert the image to colored ANSII/Unicode I would be super interested but it isn't the answer to this question.


This is a follow-up question to:   In order to know which ligatures I might consider disabling (I have in mind microtype's \DisableLigatures command; some important notes about selective disabling of ligatures are found under ), knowledge about which ligatures might be applied will be very useful. Which ligatures do the fonts used in my document offer?


I am using "^[(\+[0-9]{1,3}\.[0-9]{4,14}(?:x.+)?]$"  regex to validate phone number. I want it to work for international numbers as well. It is working for the patterns: +4454475294x364  I want to add space and '-' also.  example: +44 544-75294 x364.  What changes I need more in my regex.  Thanks.


I am trying to calculate the "overall" median of a variable that is spread across two datasets. I have access to the raw data in each dataset but can't bring their raw data together. What would be the best way to calculate the median (or any quantile for that matter)? What I was thinking to do was to get the quantiles from the "remote" dataset, say with N_1 samples and bring them to the other dataset; then sample N_1 values from these quantiles (essentially discrete empirical CDF) and use these values as "raw" scores to calculate the overall median or any other quantile. I wonder if there is a more sophisticated way of doing this? I can't combine the two datasets because of data governance issues, where I have to analyse them separately on different computers.


Electromagnetic wave and quantum mechanics

I'm very new to physics. I studied and read about quantum mechanics and what the assumptions are (wave particle duality, uncertainty principle, observation, wave function collapse, etc.), but I also have been reading about electromagnetism.  I have several questions about electromagnetism (electromagnetic radiation) and quantum mechanics.   The oscillating electromagnetic wave, why is the wave oscillating between electric and magnetic waves? Is the photon creating the electric field and then it is creating the magnetic field? How specifically does the wave works in simple terms? Why don't the photon or the electron in the wave just go outside the wave and what is holding them together to form a wave? This is more classical electromagnetic wave question. When reading about quantum mechanics, there is always talk of uncertainty of finding the electron, but it seems to contradict the electromagnetic wave? The wave is in predictable places and is oscillating between electric and magnetic field (nicely)? How is the nice fluid electromagnetic radiation wave interpreted in quantum mechanics? Is there any contradiction? In other words I don't see the craziness of quantum mechanics being seen or applied to electromagnetic wave? Am I missing something?   Thank you for your answer. I'm just trying to understand the classical electrodynamics in quantum mechanical uncertainty-way. I'm looking for a simple answer for quite a newbie and any pointers for further reading of the fundamentals of electromagnetic wave being reconciled with the quantum superposition.


How to use Airtel 4G LTE Dongle with Ubuntu?

I have recently installed Ubuntu 13.04 in my PC. Everything works fine except my Airtel 4G LTE dongle (Model MF825A). Ubuntu does not give any option to select 4G LTE when setting up a mobile broadband connection.   How can Airtel 4G LTE (Model MF825A) dongle be used with Ubuntu? Are there any patches or other updates available for getting this problem solved?


What's the smallest number that we don't know if it's prime or composite?

What's the biggest $n$ such that for all $1<x<n$, we know for sure if $x$ is prime?  The smallest primes are easy to find, and the biggest ones we haven't found yet. At the top, we have Mersenne primes, but not all primes are Mersenne primes. There's an unclear boundry, up to which we know some of the primes, but probably not all.


Which is the biggest object which can interfere with itself?

I've heard that scientist proof that viruses of  the Tobacco mosaic virus could interfere with themselves. I'm referring to quantum interference-- the same as photons. Unfortunately, I couldn't find any material on this problem on the Internet , so I don't know if it's true. Viruses have a width between 20nm and 1000nm, so they should be applied to mesoscopic physics, where that phenomenon is possible.   Is there proof that some species of virus can interfere with themselves?  If not, which is the biggest object where we may observe that interference?


Suppose $f$ and $g$ are entire functions, and $|f(z)| \leq |g(z)|$ for all $z \in \mathbb{C}$, Prove that $f(z)=cg(z)$.   My try :  I consider $h(z)=\frac{f(z)}{g(z)}$. If I prove that $h(z)$ is entire, using the fact that $|h(z)|\leq 1$, the result follows immediately from Liouville's theorem.  To prove that $h(z)$ is entire, I have to prove that $h(z)$ has removable singularities at possible zeros of $g(z)$.  Suppose $g(z_0)=0 \Rightarrow |g(z_0)|=0 \Rightarrow |f(z_0)|=0$, BUT what if $z_0$ be a root of of order $k$ of $g(z)$ (i.e. $f^{(n)}(z_0) = 0 $ for all $ 0 \leq n \leq k-1$) and be a zero of order $m$ of $f(z)$ and $k>m$ ?  And if that's not the case, how to rigorously show that $z_0$ is a removable singularity ?  Thank you all in advance.


/etc/sudoers file ignored or overrriden somehow?

Here are the contents of my /etc/sudoers file  $ sudo cat /etc/sudoers # # This file MUST be edited with the 'visudo' command as root. # # Please consider adding local content in /etc/sudoers.d/ instead of # directly modifying this file. # # See the man page for details on how to write a sudoers file. # Defaults    env_reset Defaults    mail_badpass Defaults    secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"  # Host alias specification  # User alias specification  # Cmnd alias specification  # User privilege specification root    ALL=(ALL:ALL) ALL  pkaramol ALL=(ALL:ALL) NOPASSWD:ALL # Members of the admin group may gain root privileges %admin ALL=(ALL) ALL  # Allow members of group sudo to execute any command %sudo   ALL=(ALL:ALL) ALL  # See sudoers(5) for more information on "#include" directives:  #includedir /etc/sudoers.d   And here is what's inside /etc/sudoers.d  /home/pkaramol $ sudo ls /etc/sudoers.d/ README   However, still no password-less sudo:  /home/pkaramol $ sudo -k /home/pkaramol $ sudo -i [sudo] password for pkaramol:    Why is that?