Study the following limit: $$ \lim\limits_{ (x,y,z) \to (0,0,0) } \frac{xy-z^2}{x^2+y^2+z^2} $$   I'm not sure if this way of proving that the limit does not exist is correct so I'm this is basically for a proof verification.  Approaching $(0,0,0)$ through the plane $z=0$, then the limit becomes  $$ \lim\limits_{ (x,y) \to (0,0) } \frac{xy}{x^2+y^2} $$  Now this limit does not exist, because approaching $(0,0)$ through the line $y=0$, the limit becomes  $$ \lim\limits_{ x \to 0 } \frac{0}{x^2} =0$$  But if we approach $(0,0)$ through the line $y=x$ we have that  $$ \lim\limits_{ (x,x) \to (0,0) } \frac{x^2}{2x^2}=\lim\limits_{ (x,x) \to (0,0) } \frac{1}{2} =\frac{1}{2}$$  So the limit $ \lim\limits_{ (x,y) \to (0,0) } \frac{xy}{x^2+y^2} $ doesn't exist. This means that the limit we began with doesn't exist, correct?


Lenovo Thunderbolt 3 Dock ethernet 17.04

Coming from a Dell E series to the Lenovo X1 Carbon (5th Gen).  Got the Lenovo Thunderbolt 3 dock to go with it.  Had to disable thunderbolt security in the BIOS to get the USB and other ports working.  Can't get the ethernet working.  It only sees the internal ethernet card.  I saw somewhere else that it is a realtek 8152, and I looked at dmsg and found this:  [    3.505021] usbcore: registered new interface driver r8152 [    3.647253] r8152 6-1:1.0 (unnamed net_device) (uninitialized): Unknown version 0x6010 [    3.647255] r8152 6-1:1.0 (unnamed net_device) (uninitialized): Unknown Device   Not sure where to go from here.  Any ideas?  Thanks.  lsusb:  Bus 006 Device 002: ID 17ef:3069 Lenovo  Bus 006 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 005 Device 003: ID 046d:c404 Logitech, Inc. TrackMan Wheel Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 004: ID 17ef:3066 Lenovo  Bus 003 Device 003: ID 13ba:0017 PCPlay PS/2 Keyboard+Mouse Adapter Bus 003 Device 002: ID 17ef:306a Lenovo  Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 004: ID 138a:0097 Validity Sensors, Inc.  Bus 001 Device 003: ID 04f2:b5ce Chicony Electronics Co., Ltd  Bus 001 Device 002: ID 8087:0a2b Intel Corp.  Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub   Yes, docked  usb-devices | awk '/17ef/' RS=  T:  Bus=06 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=5000 MxCh= 0 D:  Ver= 3.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 9 #Cfgs=  2 P:  Vendor=17ef ProdID=3069 Rev=31.03 S:  Manufacturer=Lenovo S:  Product=ThinkPad TBT3 LAN S:  SerialNumber=301000001 C:  #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=288mA I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=00 Driver=(none)


Is there a way to customize keyboard shortcuts for Outlook 2013?

I've searched a fair deal, but the  I found was for Word 2013, but the same steps don't work for Outlook.  Is there a way to customize Outlook 2013's keyboard shortcuts?


Why does `++a++` not compile in C++ but `(++a)++` does?

What the title says. For C++, (++a)++ does compile. Strangely enough, though, ++(a++) does not:  int main() {     int a = 0;     ++a++; // does not compile     (++a)++; // does compile     ++(a++); // does not compile }   But in Java, it does not for all three:  public class Test {     public static void main(String[] args) {         int a = 0;         ++a++; // does not compile         (++a)++; // does not compile         ++(a++); // does not compile     } }   Is there any reason why C++ compiles this but not in Java?


I was looking for a way to see what was edited in one of my questions on the Android app, but there doesn't seem to be a way of viewing the edit history.  Is there a way to fo this and if not can we add it in?


I would like to know how to find multiplicative inverses in $\mathrm{GF}(2^8)$. I know how to multiply two elements of $\mathrm{GF}(2^8)$ (for example, I know that 0x1b*0xaa equals 0x8c).  I follow , but I still don't understand the process. More specifically: How exactly (step-by-step) are logarithm and antilogarithm tables for AES' finite field formed?


I'm fairly new to Blender, in fact, I've been '3d modelling' in Blender for no longer than 10 days. While my 3d modelling skills are slowly getting sharpened I'm completely clueless on how I would unwrap this model I'm currently working on. This is an asset for a game, by the way is far from be finished, but I wanted to test the components scales, so I though, let me chuck some materials and see how it look in the game with proper lighting and stuff... I couldn't be more disappointed with the results. Here's my model in Blender:  And here's how it looks when I import it to my game using smart UV project or lightmap pack to generate the texture.  Like I said, I'm fairly new to Blender and based on the researches I did, it seems that I should be using seams although I also noticed that there are several different strategies, and I have no idea where to start from... So if somebody could provide some sort of guidance, or point me into a tutorial, or something that would help me to solve this problem I would very much appreciate. PS: I can link my 3d model if necessary. Thanks!


I was trying to log in to  (with the Stack Exchange account) and keep getting the "Oops! Something Bad Happened" page indicating there is something wrong.  Is there something going on right now?  I tried this both on Chrome (v31) and IE8.


Trying to use setConverter() on my comboBox, but I get a null pointer exception if I put it in my initialize function

The convertCombo() in my initialize method causes a null pointer exception, and I am not sure why. Is there any better way to convert my Objects User in the combo box so its a readable String, but still keep it as an object in the combobox so I can pass the ID from my object for later use. public class SelectionController implements Initializable {      @FXML     private ComboBox<User> combobox;     @FXML     private Button selectButton;                    @Override     public void initialize(URL arg, ResourceBundle arg2) {         try {             Connection conn = DBConnecter.getConnection();             ResultSet rs = conn.createStatement().executeQuery("SELECT id,fname FROM students");             ObservableList<User> data = FXCollections.observableArrayList();             if(conn != null) {                 System.out.println("connected");             }             while(rs.next()) {                 data.add(new User(rs.getInt("id"),rs.getString("fname")));             }             combobox.setItems(data);             convertCombo();         } catch (Exception e) {             e.printStackTrace();         }               }              public void convertCombo() {         combobox.setConverter(new StringConverter<User>() {              @Override             public User fromString(String arg) {                 return null;             }              @Override             public String toString(User arg) {                 return arg.getName();             }                      });     }      }


$post->ID not working but the get_the_id() is

I created a custom post type from a Plugin. Then in a function like show_data() I queried the post type along with its post meta data (Custom Fields). Then in Page Template I used the function to show the queried data. Within the loop I did something like:  while( $my_query->have_posts() ){    $my_query->the_post();     echo $post->ID;     echo get_the_id();     echo get_post_meta( $post->ID, 'my_field', true );     echo get_the_title();  } wp_reset_postdata();   I did not return anything but simply those echos. And in my Page Template I used simply:  show_data();   Now the problem is: the loop is showing the Post Title (get_the_title()) and the post ID from get_the_id() only.  But the $post->ID is not showing the ID, so the post_meta is not showing too.  What can cause the problem?


Expansion of $(a+b+c+d+e+....)^n$, but with all coefficients equal to 1.

I'm looking for a formula to calculate the sum of $(a+b+c+d+...)^n$ but with coefficients equal to 1. For example in $(a+b+c)^2$. I want the sum of $a^2 + b^2 + c^2 + ab + bc + ca$. And for $(a+b+c+d)^3$, I want the sum of $a^3 + b^3 + c^3 + a^2b + a^2c + b^2a + b^2c + c^2a + c^2b + abc$. Similarly, I want the sum of expansion of $(a+b+c+d+e+....)^n$ with coefficient equal to 1. I tried to find the pattern by expanding the $(a+b+c)^2$. And I found that its formula is $a^2 + b^2 + c^2$ + $\frac{((a+b+c)^2 - a^2-b^2-c^2)}{2}$. This works for the power of 2. But fails on other powers. Any help will be really appreciated.


Under what license is Ubuntu? Can it be legally modified and distributed?

What license does Ubuntu fall into (GPL, MIT, a mix)? Would it be legal to modify it and redistribute my modified version?


Beamer ignoring a \label when used inside certain \only's

For space reasons I want to break up the contents of an itemize list into separate slides, which I have been doing without much problem using \only.  However, the following minimal document complains that the label eq:formula is not defined:  \documentclass{beamer} \begin{document} \begin{frame}{Title}  \begin{itemize}  \only<1>{   \item Item 1.  }             % Comment   \only<2>{     % these lines   \item Item 2, with equation   \begin{equation}    \label{eq:formula}    xyz   \end{equation}    \item Item 3, with reference \eqref{eq:formula}.  }  \end{itemize} \end{frame} \end{document}   As you can see, it is clearly defined.  The problem goes away if you comment out the marked lines (thus, printing everything on one slide).  I see using \tracingmacros that there is a serious redefinition of \label in beamer, and as such it appears that this is a bug with detecting what slide the label is printed on.  Is that right, and what is the solution?


My webhoster seems to have some troubles with DDOS attacks and routing overload. This makes my IP to be not available sometimes and I'd like to add a failover IP for the domain.  However, 2 A-Records means that it's similar to a load balancer which is NOT what i am looking for. I do not want the fallback machine to be accessed any time - except in case of real troubles or downtime of first choice IP.  Is there a out-of-the box solution that allows me such a failover ip?  If not, if it requires a DNS re-configuration: Is there a recommended script or similar that can be run on the secondary machine (of course, this is with a different hoster). This has to check whether the first choice ip is down and must overwrite the A-record, right? This requires my domain hoster to provide an API for the DNS settings...


Having Trouble Finding a Faculty Member for Math Undergraduate Research

I am an undergraduate pursuing mathematics and computer science in the research university at U.S.  Inspired from the applications of algebra to math and statistics, I have been trying to find a suitable project in the mathematics with supervision from a faculty member, or a reading course in some topics of the pure mathematics.  I have been sending emails to professors at the math department for either a reading course or a project (regardless of the difficulty) I can pursue, but they are either not interested or ignoring my emails and corresponding followup reminders.  When I visited one of faculties during her office hour, she told me that she have been ignoring my emails since she is not interested in my proposal of research idea (I felt sad for a while as I hope she just informed me she is not available).    The general outline is that I approach professors doing research similar to my interest, and ask them if they have any available project.  If they do not have projects, then I ask them if they are interested in hearing about my own ideas.  I am started to feel anxious about it as I really like to work with professors in the mathematics (my interests are not really in the domain of CS, but more or less the pure mathematics and its applications in theories of CS); I am interested in their research, but they are not interested. I understand the busy schedules of professors, so I am curious if there us any way to approach them to acquire the opportunities of project or reading course. So far, none of the professors at the department is interested or available...


I am currently in the process of reading a book on C++, and in this book the author explains that it is better to use a constant rather than NULL macro, but without really explaining why or giving any advantages or disadvantages.  So why it's better to do use:   const int NULL = 0; int *ptr = NULL;   instead of:  int *ptr = NULL;   The only explanation is given is that the NULL macro is not type-safe.


Apache POI remove multiple columns effectively

I have a program which changes multiple excel files in given directory. I need to remove multiple columns from excel file. For example, I want to remove all columns after 5th.  private void deleteColumns(Sheet sheet, int columnIndex) {     for (Row row : sheet) {         int j = 0;          for (Cell cell : row) {             if (j >= columnIndex) {                 row.removeCell(cell);             }             j++;         }     } }   I get ConcurrentModificationException.  I saw a post on how to delete a cell.   This idea is clear for me. I will need to create a row, clone necessary cells there, and remove the row.   What are other solutions?  I also tried to create a substitute row, to clone cells which I need, and then remove the original row. I took this idea from here.    I would like to see some better solutions, with less code or more effective then removing cells one by one.


Prop: If two functions $f,g$ are bijective, their compositions are also bijective.  Pf: Let $f:A\rightarrow B$ and $g : B \rightarrow A$. By definition, an injective function is invertible.  $f(g(x)) = f(g(y))$. Since $g$ is a bijection, $f(f^{-1}(x)) = f(f^{-1}(y)) \implies x = y$. Then, $f(g(x)) = f(g(y))$ is a bijection.   Conversely, $g(f(x)) = g(f(y)) \implies g(g^{-1}(x))=g(g^{-1}(y)) \implies x =y$.  $g(f(x))=g(f(y))$ is also a bijection as required.


I'm trying to prove that $L = \{ww^R : w \in \{a,b\}^*\}$ ($w^R$ is the reverse of $w$) is not regular using the pumping lemma.  Let $p$ be the pumping length and $s = a^pbba^p$.  $x = \epsilon$, $y = a^p$, $z = bba^p \implies s = \epsilon a^p bba^p = a^pbba^p$  1) Was $s$ properly divided?  Let's see:  $|xy| \leq p$  $|y| > 0$ (I'm not sure about this since $|y|$ depends on $p$?)  If we take $i = 2$, $xyyz = \epsilon a^p a^p bba^p \notin L$, so $L$ is not regular.  2) What about $i = 0$? $xz = \epsilon bba^p \notin L$, so $L$ is not regular.


"Name" class nullpointerexception; attempting to rework code

I have looked at "What is a NullPointerException and how do I fix it?", although that question and its answers simply don't help. I understand my problem; the "NameTest" program is attempting to reference the "Name" object while it's null, but I'm not sure how to rework it to fix this, as I want the lastName, firstName, and fullName to be accessible by all "Name" methods. In the "Name" program, I'm attempting to create a "Name" class, with which a blank name object can be created, and then later assign a String/Stringbuffer value (depending which would work better) with setName() method. Here is the "Name" code:  public class Name { private StringBuffer lastName; private StringBuffer firstName; private StringBuffer fullName;  public Name() {     lastName.replace( 0, 0, "" );     firstName.replace( 0, 0, "" );     fullName.replace( 0, 0, "" ); }  public Name( String lN, String fiN ) {      lastName.replace( 0, lN.length() - 1, lN );       firstName.replace( 0, fiN.length() - 1, fiN );            fullName.replace( 0, (lastName.length() + firstName.length()) + 2, lastName + ", " + firstName); }  public Name( String fuN ) {     String[] fuNTemp = fuN.split( ", " );     lastName.replace( 0, fuNTemp[0].length() - 1, fuNTemp[0] );     firstName.replace( 0, fuNTemp[1].length() - 1, fuNTemp[1] );      fullName.replace( 0, (lastName.length() + firstName.length()) + 2, lastName + ", " + firstName); }  public void setName( String n ) {     String[] nTemp = n.split( ", " );     lastName.replace( 0, nTemp[0].length() - 1, nTemp[0] );     firstName.replace( 0, nTemp[1].length() - 1, nTemp[1] );      fullName.replace( 0, (lastName.length() + firstName.length()) + 2, lastName + ", " + firstName); }  public void setName( String lN, String fiN ) {     lastName.equals( lN );     firstName.equals( fiN );      fullName.equals( lastName + ", " + firstName ); }   public StringBuffer getName() {     return fullName; } }   Here is the program "NameTest", which I created simply to help figure out "Name":  public class NameTest { public static void main( String [] args ) {     Name test = new Name();      System.out.println( test.getName() );     System.out.println();      String Doe = new String( "Doe" );     String John = new String( "John" );      test.setName( Doe, John );      System.out.println( test.getName() ); } }   Here is the error message from "NameTest":  Exception in thread "main" java.lang.NullPointerException     at Name.<init>(Name.java:9)     at NameTest.main(NameTest.java:5)


How to prevent a \lstinputlisting being split across pages?

shows how to prevent a long listing from being split across several pages when the code is written directly into the tex file. I want to achieve the same effect when including code in separate files using \lstinputlisting like so:  \lstinputlisting[label=lst:mylist,caption=A Caption]{code/parametrised.xml}   How do I modify the listing environment definition given in the above question to do so?  \lstnewenvironment{code}[1][]%   {\minipage{\linewidth}     \lstset{basicstyle=\ttfamily\footnotesize,frame=single,#1}}   {\endminipage}   Any help would be greatly appreciated!  Edit: The question has been rephrased for clarity - The answers here relate to preventing a listing from being split across pages by ensuring it's treated like a unbreakable float. Howvever, this also means that listings longer than a page will not be paginated and will run off the bottom of the page.


Sequential Menu (Drill down) or Accordion

I have 3 levels in my information architecture for my desktop dashboard. In the vertical navigation which measures H:500px W:200px I have;   Top level: 8 items Second level: 9 items in total (one of my top level item has 7 second levels) Third level: 12 items   Would you use an accordion style (which will make the menu long when expanded) or a sequential drill down menu? and why?  Cheers,  Chris


Some reference on quadratic rings or introductory algebraic number theory.

I have found many posts on this matter. But none of them fulfills my purpose. So I am describing my situation briely. I have read ring theory from Dummit & Foote. I have been reading some field theory from the book Galois theory by Rotman. I am particularly interested in quadratic integer rings. I've also read some articles on this and started to read the number theory book by Ireland and Rosen. I really liked the subject. But while reading some things didn't come to naturally, like when they introduced universal side divisors and proved some integral domains are not euclidean domains and when they introduced Dedekind-Hasse norm and proved R is a PID iff R has a D-H norm. These were especially the parts I liked the most. But the applications of these were really hard (very manipulative). I would really like to read more about this area. Although I don't want to start algebraic number theory now. Any introductory or intermediate reference or some expostiory articles will be helpful.


MySql calculate number of connections needed

I am trying to figure my needs regarding web service hosting.  After trying Azure I have realized that the default MySql they provide (through a third party) limits the account to 4 connections. You can then upgrade the account to 15, 30 or 40 connections (which is quite expensive). Their 15 connections plan is descirbed as:      "Excellent choice for light test and staging apps that need a reliable   MySQL database".   I have 2 questions:   if my application is a web service which needs to preform ~120k Queries a day (Normal/BELL distribution) and each query is ~150ms(duration)/~400ms(fetch), how many connection do I need? If instead of using cloud computing, I will choose a VPS, how many connections will I be able to handle on a 1GB 2 cores VPS?   Thank you!


I understand that you'se is not considered a formal English word by the Oxford. Colloquially, many people use the word you'se all the time in common conversation. As such, there is a gap in formal English for pointing out the subject as two or more people being adressed.  For example, if I were to say      You should buy that Lear Jet.   It would be pronounced the same as      You [people] should buy that Lear Jet.   The only thing separating the two statements is context, which is sometimes hard to encapsulate across different media etc.  Why then is you'se not a formal word for this situation?  For example:     You'se [all people being addressed] should buy that Lear Jet.   It becomes obvious that verbally, the pronoun of the conversation is now referencing more than one person and dispelling confusion. I understand that ye was the Middle English form of this word. As such, why is you'se frowned upon?  Edit: For non-Australians, the word you'se is equivalent to y'all and can be substituted throughout my question.


Theorem 20 Hoffman Kunze Linear Algebra book Section 3.6

What I don't understand here is why is $h(\alpha)=0$ for all $\alpha$ in $N_{k}$. Is there a typo?  In case there is not, could someone please detail that last step please?


What are positive contributions to SO when you have a ban?

Suppose my account is banned for questions. I have 2 questions:   Is retagging a positive contribution to SO? Is editing a positive contribution to SO?


Is there any mention of the lands east of Mordor?

Sauron seems to have huge armies east of Mordor, the Blue Wizards went there and didn't come back, and early maps of Arda when it was still flat show rough landmarks, but not much, and everything changed after the Second Age.  Is there any canonical information about the East?


Determine all units of the domain $\mathbb{Z}[\sqrt{2}]$

I would like to determine all units of the domain $\mathbb{Z}[\sqrt{2}]$.    Recall that if $D$ is an integral domain, then a unit of $D$ is an associate of the multiplicative identity $1$, i.e. $u \in D$ is a unit iff $u$ divides $1$ and $1$ also divides $u$. Equivalently, $u \in D$ is a unit iff it is a divisor of $1$, i.e.  iff $\exists x \in D$ such that $ux=1$.  Thus, units are also called invertible elements.  The set $\mathbb{Z}[\sqrt{2}] := \{a+b \sqrt{2}: a,b \in \mathbb{Z} \}$, under the usual addition and multiplication operations, forms a domain.  How do I find all its units?  Suppose $a+b \sqrt{2}$ is a unit. Then $(a+b \sqrt{2})(x+y \sqrt{2})=1$ for some $x,y \in \mathbb{Z}$. Thus, $ax+2by=1$ and $ay+bx=0$.  Solving for $x,y$, we obtain that $x=\frac{a}{a^2 - 2b^2}$ and $y=\frac{-b}{a^2 - 2b^2}$ must be integers.  How do I obtain the set of values of $a,b$ for which $x$ and $y$ are integral?   Since $(\sqrt{2}-1)(\sqrt{2}+1)= 2-1^2=1$, the two factors $\pm 1 + 1 \sqrt{2}$ are units.  Can we systematically find all the units of $\mathbb{Z}[\sqrt{2}]$?   This answer given  to a related question shows only that if $a+b \sqrt{2}$ is a unit and  is > 1, and if $a,b>0$, then $a+b \sqrt{2}$ is of the form $(1+\sqrt{2})^n$.  The case where $a,b$ are of opposite signs, and the case where the unit is between 0 and 1 (such units exist, for eg, $3-2 \sqrt{2}$) are open.


Opening document library files in popup or new window

Is there any easy way to open the document library files in a new window or popup depending on the file types?  e.g. PDF - In Adobe reader (currently opens in IE)  Image file (currently opens in IE)


Using Wilson's theorem, show that if $p$ is prime of the form $p=4n+1$ and if $y=(\frac {p-1}2)!$, then $y^2\equiv -1\mod p$.   My attempt: By Wilson, $(4n+1-1)!\equiv (4n+1-1) \mod p$,$(4n)!\equiv4n\mod p$. The statement we want to show is equivalent to  $((2n)!)^2\equiv 4n\mod p$, which is transformed into $((2n)!)^2\equiv (4n)!\mod p$


"There is no argument given that corresponds to the required formal parameter" - when trying to test OOP Inheritance

I'm just trying to understand how Inheritance works in C#. (even though I think I got it, I want to try to do something practical in order to understand)  So I've been trying to create a class with a property and a constructor and another one which inherits this one. But I get an error and I don't really seem to get why.  using System; using System.Collections.Generic; using System.Text;  namespace ConsoleApp2 {     public class Test     {         public int testing { get; }         public Test(int p)         {             this.testing = p;         }     }     public class Test2 : Test {      } }   There is no argument given that corresponds to the required formal parameter 'p' of 'Test.Test(int)' for line 15   Can someone help me understand what's happening and why do I get that error? Thanks.


i wanted to know why i can't transform all my letter into lowercase in my string in my function. I try to print the string before the "if" and it worked so i dont understand why i cannot do :  string[i] = string[i] - 'A' + 'a';   Here my function :  bool is_string_in_array(char * strings[], int n, char * string) {   for (int i=0;i<strlen(string);i++) {         printf("%c\n",string[i]);     if (string[i] >= 'A' && string[i] <= 'Z') {         string[i] = string[i] - 'A' + 'a';      } } for (int i = 0; i < n; i++) {     if (strcmp(strings[i], string) == 0){         return true;     } } return false;   }  And i can not use tolower() function ... and i called with :  char *test ={"DOG"}; is_string_in_array(banned_words,n,test);   Thank you for your time


When I run the debugger: "failed to set controlling terminal"

In a book I read, the author's CPU was 32-bit. Mine is 64-bit. I run the NASM assembler in the terminal with:  nasm -f elf -g -F stabs asmwork/eatsyscall.asm   Then I run the linker:  ld -o eatsyscall eatsyscall.o   This returned:  ld: i386 architecture of input file eatsyscall.o is incompatible with i386:x86-64 output  I read some answers and it said I needed to use elf64 (not as the book said). I run the assembler and it solved this message.  Now I run in the terminal kdbg eatsyscall.o. It opens the KDbg software and KDbg: Program output.  I select a breakpoint in a line and as usual a red circle appears. I click run and the red circle is not changed for an arrow. Instead in the KDbg: Program output it outputs this message (I'm not showing where the .o file is as in the output it is written):  warning: GDB: Failed to set controlling terminal: Operation not permitted  /bin/bash: Permission denied  /bin/bash: line 0: exec: cannot execute: Permission denied.   Or on one occasion, just this message:  warning: GDB: Failed to set controlling terminal: Operation not permitted     In Settings > Global Options I have the following.   How to invoke GDB: gdb --fullname --nx Terminal for program output: xterm -name kdbgio -title %T -e sh -c %C     What can I do? Why do I get a permission error? Is it something related to the command sudo?    UPDATE  For running the debugger I have used kdbg program and kdbg ./program. The executable file I want to debug is called program and it is located in the folder asmwork. When my working directory is with that folder, I write ls -l and I get the following about the file:  -rwxrwxr-x 1 adam adam 1304 יול 24 17:56 program


Minecraft Bedrock Server and Minecraft on Same PC - Minecraft doesn't see server

I was hoping to get information from the same question in another location but it never got answered and posting another question to it wasn't allowed.  So I'll just ask it again.  Windows 10 Minecraft Windows/Bedrock Edition - whatever it is called   I installed, setup, and ran the server on my main PC on my home network. My son fired up Minecraft on his computer also on the home network. He was able to easily connect to the server. I then connected to it on my Android phone with no problems. Since that worked I bought another copy of Minecraft to play on my PC, the same PC running the server. Minecraft on my PC doesn't even see it...there are no options for LAN under the friends tab. I read in the "bedrock_server_how_to.html" and in the other question here that I might need to run a command in the CMD as admin, but neither location mentions any special instructions other than that. I ran that command, in CMD, as admin.  CMD responded with "OK" I tried this with the server running and it didn't work. I then closed the server and tried it again, fired the server back up, fired Minecraft back up, still no luck.   How exactly should I get Minecraft on my machine to see the server?  Everyone else on the network can see it.  Internet works fine.  My old TF2 server works fine and I can play it from this machine. Etc, etc, etc.


In Apostol's "Introduction to Analytic Number Theory", there is a definition for the Riemann Zeta Function for $0<s<1$.    Is there a justification for this formula?


I try to install menulibre, but i get this error Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  menulibre : Depends: python3-psutil but it is not installable E: Unable to correct problems, you have held broken packages.  When i try to install psutill, i got: flitzcore@flitzcore-Lenovo-G470:~$ sudo apt-get update Hit:1 http://ppa.launchpad.net/kdenlive/kdenlive-stable/ubuntu focal InRelease Hit:2 http://archive.ubuntu.com/ubuntu focal InRelease                      Hit:3 http://ppa.launchpad.net/uget-team/ppa/ubuntu focal InRelease       Reading package lists... Done flitzcore@flitzcore-Lenovo-G470:~$ sudo apt install python3-psutil Reading package lists... Done Building dependency tree        Reading state information... Done Package python3-psutil is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'python3-psutil' has no installation candidate  Anyone know how to solve this problem?


I have recently read in English grammar book like this:     You___________ your notebooks from tomorrow   1. need not bring   2. need not to bring      The answer is need not bring   But why not another?


For primes $p≡3\pmod 4$, prove that $[(p−1)/2]!≡±1\pmod p$.

I know to use Wilson's Theorem and that each element in the second half is congruent to the negative of the first half, but I'm not sure how to construct a proof for it.


Let a,b and c be the three sides of a triangle. Show that $\dfrac 1a+\dfrac 1b+\dfrac 1c\le \dfrac 1{a+b-c}+\dfrac 1{a-b+c}+\dfrac 1{-a+b+c}.$ When does equality occur? I have used the Ravi-transformation and obtained $\frac{1}{x+y} + \frac{1}{x+z} + \frac{1}{y+z} \leq \frac{1}{(x+y)+(y+z)-(x+z)} + \frac{1}{(x+y)-(y+z)+(x+z)} \\ +  \frac{1}{-(x+y)+(y+z)+(x+z)} \Longleftrightarrow  \frac{1}{x+y} + \frac{1}{x+z} + \frac{1}{y+z} \leq \frac{1}{2x} + \frac{1}{2y} + \frac{1}{2z}.$ But I get stuck here. Does anyone have an idea to proceed?


How far could the "Eye of Sauron" see and what is its resolution?

How far and how clear could the "Eye of Sauron" see? Could it see through the whole of Middle-earth or is it limited to only Mordor? Could it distinguish the human face, the small artifacts like rings, or not? Saruman says the "Eye of Sauron"  "sees all — his gaze pierces cloud, shadow, earth and flesh. You know of what I speak, Gandalf — a great Eye… lidless… wreathed in flame"  when he is intimidating Gandalf. This implies that Sauron could see everything, just like Superman. If this is true, how could the One Ring escape his gaze? Sauron just needed to scan the land of the Shire. I am afraid that the meeting in Rivendell is also under Sauron's sight. When Frodo brings up the One Ring and Gimli wields his axe, Sauron will see. And once he saw the Ring, he can see it always. Does this mean that Saruman is exaggerating? What is the true limit of the "Eye of Sauron"?


Unable to drag & drop icons & links from firefox (I'm New)

Hi so I recently switched over to Ubuntu and one things that I dislike is that I'm unable to drag & drop icons & links from firefox to my desktop. I checked under permissions and I have full permission.


No WiFi internet on Ubuntu under VirtualBox

I have just installed Ubuntu 14.04 under VirtualBox 4.3.20 on a Windows 8.1 host. I can't get any internet access over WiFi (and I can't get an Ethernet connection anywhere near the computer). All of the help I can find when I Google this problem either a) tells me to change Windows 7 settings that I can't find in Windows 8.1, or b) tells me to sudo apt-get install something, which doesn't work because I have no internet connection.  Can somebody tell me in easy steps (I don't really know Linux, and I certainly don't know networking) how to get the internet connection working?  Thanks.


squidguard issue configuring.getting same error over and over again

Well, I installed Squid3 the other day and then installed Quintolabs, but I discovered this program squidguard that looks much easier to work with and configure and it looks like it would serve as a more adequate web filter for my needs.   I installed squidguard seemingly without a problem and I am following .  I am at the part when I just finished installing the blacklist and now I am trying to do a test run of squidguard with output to stderr using the command squidGuard -d (I am a total newbie with linux and am not that familiar with any commands or the file system or anything being used to Windows for so long).  This is what shows in the terminal which includes the error:  administrator@LinuxWebFilter:~$ squidGuard -d squidGuard: error while loading shared libraries: libdb-4.8.so: cannot open shared object file: No such file or directory   I have no idea what to do or how to fix this.  Can someone please help with this?


So I've got a persistent program running in the background. Killing it just causes it to restart with a different PID. I'd like to suspend it (put it to sleep without actually killing it). Does kill -9 do this? If not, how should this be done?


Proof of a proposition about recursion definition (Terence Tao's Analysis I)

Exercise 3.5.12. Let $ f: \mathbb N \times \mathbb N \to \mathbb N$ be a function, and let c be a natural number. Show that there exists a function $a:\mathbb N\to \mathbb N$ such that $$a(0)=c$$ and $$a(n++)=f(n,a(n))\;for\;all\;n\in \mathbb N,$$ and furthermore that this function is unique. Tao gives the hint: first show inductively, by a modification of the proof of Lemma 3.5.12, that for every natural number $N\in \mathbb N$, there exists a unique function $a_N:\{ n\in \mathbb N:n\lt N\}\to \mathbb N $ such that $a_N(0)=c$ and $ a_N(n++)=f(n,a(n))$ for all $n\in \mathbb N$ such that $n\lt N$.  In my opinion, we could solve it by proving that $\forall n\in \mathbb N,a(n)\in \mathbb N$ according to mathematcial induction.  The property P(n) is:$$\forall n\in \mathbb N, a(n)\;is\;unique$$ P(0) is true. And if P(n) holds, P(n++) is true because different natural numbers must have different successors. $$a(n++)=f(n,a(n))$$ $$a(m++)=f(m,a(m))$$ $$n++=m++\Rightarrow n=m\Rightarrow a(n++)=a(m++)$$ It's similar to the proof of  Proposition 2.1.16 (Recursive definitions): Suppose for each natural number $n$, we have some function $f_{n} : \mathbb{N} \rightarrow \mathbb{N}$ from the natural numbers to the natural numbers. Let $c$ be a natural number. Then we can assign a unique natural number $a_{n}$ to each natural number $n$, such that $a_{0} = c$ and $a_{n{++}} = f_{n} (a_{n})$ for each natural number $n$.  This proof indicates both the existence and uniqueness of the function $a$. I don't know why Tao says it's informal.  But regarding the hint, how do we get the function f even if we've got the conclusion from the hint. Also it seems like the function a(n) can be diffentent considering different N. I don't know if the hint is correct.


My Ipad locked on it on I don't remember my I cloud ID or Password How do I unlock it? It came up on my Ipad Activation lock.


Mail App keeps popping up in the background in Mac OS Mojave

When I am doing some work on my macbook pro, Mail app's main window keeps popping up in the background, it even pops up when I watch movies by interrupting full screen. This is so frustrating, I can't find out solution to this, googled and went to many discussion forums, no luck, suggestions that I found are very old and outdated. Has anyone faced similar issues or does anyone knows solution to this?


Orthogonality Relations Exercise, Brezis' Book Functional Analysis

I studying Brezis' book and I have somes partial solutions of the exercise $1.17.$  Let be $E$ a normed space and $f\in E^*$ be a linear functional nonzero. Consider the set  $M=[f=0]$ given by  $$M=\{x\in E \ : \ \langle f,x\rangle = 0 \}.$$  Here, $\langle f,x\rangle$ denote $f(x)$ and note that $M$ is just $\ker f$.     Dertemine $M^\perp.$   By definition   $$M^\perp=\{g\in E^* \ : \ \langle g,x\rangle=0, \forall x\in M \}.$$  So, the first doubt is: $M^\perp$ is just  $$M^\perp=\{g\in E^* \ : \ \ker f \subset \ker g  \} ?$$     Show that $\forall x\in E$, we have $d(x,M)=\inf_{y\in M}{\|x-y\|}=\frac{|\langle f,x\rangle|}{\|f\|}.$   Since $y\in M$, $|\langle f,x\rangle|=|\langle f,x-y\rangle|\le \|f\|\|x-y\|$. Then  $$\frac{|\langle f,x\rangle|}{\|f\|}\le d(x,M).$$  How can I show the equality? I know that since $\{x\}$ is a compact set and $M$ is a closed subspace of $E$, there is $y_0\in M$, such that $d(x,M)=\inf_{y\in M}{\|x-y\|}=\|x-y_0\|,$ but I don't know if that it is a help.  I tried to show that $\forall \varepsilon >0$, there is $z\in M$ such that  $$\|x-z\|<\frac{|\langle f,x\rangle|}{\|f\|}+\varepsilon,$$  but I could not. The last doubt is:     Let be $E=\{u\in C([0,1],\Bbb{R}) \ : \ u(0)=0\}$ and $f\in E^*$ given for each $u\in E$ by   $$\langle f,u\rangle = \int_0^1 u(t)dt.$$ Show that if $u\in E-M$ then $d(u,M)$ is never achieved.   For that, I tried something by absurd method but I found nothing. Can someone give a little help? Thanks.


Is an object like $$\int^0_0 x^{-1} dx$$ defined?    Context: when considering functions such as  $$f(x)=\int^{x^2}_xt^{-1}dt$$  would it therefore be necessary to give a piecewise definition of $f$ if we wished to include $0$ in the domain?    A little bit of random speculation, but if the object is supposedly defined to be $0$, then we would be allowed to write something like  $$\int^0_0\sqrt{\text{banana}}\quad d(\text{apple})=0$$  ???


Let $T = \lambda z + \mu \bar z$ where $\lambda, \mu \in \mathbb{C}$. Show that $T$ is bijective exactly when $\lambda \bar\lambda \ne \mu \bar\mu$.


Problems after installing the “New Hardware Support is Available”

Problem started July 11th 2014 when I got the update. Each time when booting up my Ubuntu 12.04 LTS, I got a black screen with this message "Could not write Bytes: Broken Pipe" on the top Left hand corner. Today I reinstalled Ubuntu 12.04 LTS and now when I click on Software updater I see “New Hardware Support is Available”. Do I really need to get this update? Is there a way to avoid it? My PC is working fine without that update...


Sensing +12V signal using ST STM8AF5288 microcontroller digital input

I am using an ST STM8AF5288 microcontroller powered by 5V in one of my projects (, ). Is it possible to directly sense a +12V signal input by port pins?  I am using a current limit resistor in the input. All the port pins in the ST STM8AF5288 microcontroller have clamping diodes. Will I able to sense a +12V signal input? Below is the circuit used in my project:


I'm fairly new to Dr. Who, just having watched some of the newer episodes, and find Daleks rather, well, odd. The idea seems to be that they probably are cheesy villains by today's standards but weren't in the 1960s, and given that modern Dr. Who does have some   monsters, .  Still, even in-universe it's hard to glean their terror. They seem slow and dumb. Perhaps they're durable but maybe you can tip them over or something. In the scenes I've watched with Daleks the show of course takes it for granted that you, the viewer, are terrified. So, why should I be?


I want to write matrices in diagram.help me

I have drawn the diagram but I can not make the matrices  \documentclass[margin=3mm]{standalone} \usepackage{amsmath,mathtools} \usepackage{tikz-cd}  \begin{document}     \begin{tikzcd}     k^2 &&\arrow[ll,shift left]       \arrow[ll,shift right,swap]     k     \end{tikzcd} \end{document}


The symbol \in doesn't seem to fit quite right in the subscript of the sum \sum_{i \in I} \Pr(A_i)  For some reason the set-membership symbol seems to be going below the I and it looks weird:  Is there any way I can get the \in symbol to look better here? Or is there something I can do to the I to make it align properly?


Is it possible for Blender to interface with other software and hardware?  I would like to create a robot and have it display feedback on motor positions, etc, in Blender.


How to Install Ubuntu in my Windows laptop

I have downloaded the Ubuntu ISO file and I am new to the Linux and in learning phase.  How can I setup Ubuntu in my laptop?


How to put an event on a class that may not be in the document using jQuery selector

Here is the code I'm trying to use :  $(document, ".openScript").on("click", function() {     $("#scriptWindow").modal("show"); });   This will call the event at any click. But because the .openScript isn't present at the beginning, if I do like below once, it won't be attached to the element that will be created after this code :  $(".openScript").on("click", function() {     $("#scriptWindow").modal("show"); });   I thought it was possible to do like the first example, is there no other way than calling the second code at any time I create an element that has the .openScript class ?


Should the noun that follows 'both' be singular or plural?

Should the noun that follows both be singular or plural? Which of the following is/are correct?  I tested both inverting and non-inverting configuration. I tested both inverting and non-inverting configurations. I tested both the inverting and non-inverting configurations. I tested both the inverting and non-inverting configuration. I tested both the inverting and the non-inverting configurations. I tested both the inverting and the non-inverting configuration.


How do I format and word my questions to avoid the "You shouldn't be doing X, do Y" answers?

This is a problem I've experienced, and i've seen it talked about outside of Stack Exchange as a criticism of it.  The basic problem is me, or someone else asking the question     How do I do X? I have attempted this, and that, but I don't understand why this isn't working.   But many responses end up like     No no no, don't do X. You should be doing Y instead. Here's how you do Y.   Y, while it'd be helpful advice, it does not solve the problem of how to properly do X. The problem continues even if you explain why you have a constraint of only doing X instead of Y.  The "" image, while it's an edit, is a great example of this.  I'd like to know how to word my questions to attempt to avoid falling into this kind of issue that doesn't really result in anyone's problem being solved.


How to use files names on command line copied in File Explorer?

In Windows File Explorer, you can highlight several files and then click the "Copy path" button from the menu.  Show below is an example.  I'd then like to process these files on the command line, preferably in a PowerShell terminal.  I've tried enclosing them in more quotes, single quotes, and backticks, to no avail. Here's an example of the files copied to the clipboard:  "C:\Users\me\100_0909.jpg" "C:\Users\me\100_0521.jpg" "C:\Users\me\100_0519.jpg"  I'd like to be able to take the files above and include them in a command like:  magick "C:\Users\me\100_0909.jpg" "C:\Users\me\100_0521.jpg" "C:\Users\me\100_0519.jpg" +append new.jpg


$$\int \sin (x^3)dx$$ I have tried some substitutions, but I haven't reached the goal... Can you help me?


Determine $"a"$ for which the system has no solutions, infinitely many solutions, or has one solution

Consider the system $$x+y+5z=-7$$ $$-2x-y-2z=5$$ $$x+2y+(a^2+9)z=4a-8 $$    Determine the value of $a$ (if any) for which the system has no solutions. Determine the value of $a$ (if any) for which the system has exactly one solution. Determine the value of $a$ (if any) for which the system has infinitely many solutions   I created a matrix: $$\begin{pmatrix} 1 &1 & 5 & \Big\vert & -7\\ -2 & -1 & -2 & \Big\vert& 5\\1 & 2 & a^2+9 & \Big\vert& 4a-8\end{pmatrix}$$ I have no idea what to do after though.


Curl of Magnetic Field in Cartesian Coordinates

I'm struggling to understand why the curl of this magnetic vector field would be zero: $$B(x,y,z)=\left(\frac{-y}{(x^2+y^2)},\frac{x}{(x^2+y^2)},0\right)$$ This cartesian field was derived from the equation for a long, straight current carrying wire, with current flowing on the Z axis. I found this derivation . Note that I removed the constants for simplicity ($\frac{\mu_0*I}{2\pi}$) If I plot this field (shown in x-y Plane), it looks obvious that it should have curl; since the magnitude of the field lines increase approaching the center, any point in this graph should "spin" clockwise. I realize that this is an intuitive definition of curl, so please correct me if I'm wrong for using it.  Also, since this equation was derived from a magnetic field equation, barring any computation error, this HAS TO have curl from Ampere's/Maxwell's Law: $$\nabla X B=\frac{1}{c}\left(4\pi J + \frac{dE}{dt}\right)$$ In the constant current example, $\frac{dE}{dt}=0$, but current density $J$ is proportional to current and distance from the wire. However, when I calculate the curl of this it results with zero: $$[-2*\frac{x^2}{(x^2 + y^2)^2} - 2*\frac{y^2}{(x^2 + y^2)^2} + \frac{2}{(x^2 + y^2)}]\hat k=0$$ If anyone could help out mistakes or poor assumptions made here, I would greatly appreciate it!


How to channel Redstone current vertically?

I'm making a door with piston sliding sideways that reacts to pressure plates. As the pressure plates are sending the current to redstone at a very low level, I need to raise it somehow, and this leads to awkward stairs of redstone.    So I'm wondering whether there are better ways of sending the redstone current up, maybe even vertically.


How to have a common height of subscripts when some got superscripts too?

I am writing a script and got a formula with inverses, and I noticed that the subscripts have a different heigth.   This is the minimal working example:  \documentclass{scrbook} \begin{document} \[ \underline{h_1 h_1^{}  h_1^{-1}} \] \end{document}    after compiling this gives     The underline isn't really necessary but it makes it easier to see the difference, the -1 in the superscript is necessary, as only using 1 in the superscript gives the same heigth in the subscripts. I would like to have all subscripts on the same heigth. My only idea was with ^{}, but as the MWE shows it still gives a small difference. Is there another solution?


When I try to render an animation i made using a tutorial all the frames are blank. I've tried everything I can find on this website and others and nothing is working. Any help?  File:


Should I write/say "Island of Guernsay", "Island of Madagascar", "Island of Taiwan", etc. or is it OK to write/say "Island Guernsay", "Island Taiwan", etc without "OF" as it is in German and Dutch? (Sorry, English is not my native language)


What were the wolves that attacked the Fellowship of the Ring?

Shortly after they were defeated by the mountain of Caradhras, the Fellowship decided to go through Moria so that they could pass the Misty Mountains. One night on their way to Moria, they were attacked by a large pack of wolves. After a little while (and with a particularly powerful spell from Gandalf) they managed to push the wolves back, but in the morning they discovered something strange:  When the full light of the morning came no signs of the wolves were to be found, and they looked in vain for the bodies of the dead. No trace of the fight remained but the charred trees and the arrows of Legolas lying on the hill-top. All were undamaged save one of which only the point was left.  "It is as I feared," said Gandalf. "These were no ordinary wolves hunting for food in the wilderness. Let us eat quickly and go!" The Lord of the Rings Book 2 Chapter 4: A Journey in the Dark  If they weren't "ordinary" wolves, what were they? I understand that they were probably servants of Sauron, but what was special about them that made their bodies apparently disappear? Where did they come from?


Fetch Metadata from Salesforce using Tooling API objects

I am building a tool in Java to fetch all the metadata from Salesforce using the Tooling API.  For Ex: I want to fetch all the profiles details including object-permission, field-premission, recordtype settings, tab setting etc. using Tooling API.  Can anyone suggest me how to fetch all these details using Tooling API?


is uniform convergent sequence leads to bounded function?

Suppose there is there is uniform convergent sequence $(f_n)$ on the set $A$, and each $f_n$ is bounded on $A$, i.e., there exist $M_n>0$ such that $|f_n(x)|\le M_n$ for all $x\in A$ Is it true that there exist a function $f$ that is bounded on set A? Can I prove it this way:  Since $f_n \to f$ uniformly on A, $\exists n \ge N$ such that $$|f_N(x) - f(x)| \le 1$$ and $$|f_n(x)-f_N(x)| \le 1$$  Therefore, $|f(x)| \le |f_N(x)|+1 \le M_N + 1$ and $|f_n(x)| \le |f_N(x)| + 1 \le M_N + 1$, $x \in A , n \ge N$  Let $M = \max\{M_1, M_2,\dots,M_N\} + 1$ : $|f_n(x)| \le M$, $\forall x\in A$  Therefore, $f$ is a bounded function on A.


Is there a name for the UK English repeating of a subject in a sentence - IE "I can do science, me"

The catchphrase of an old British science show called Brainiac is "I can do science, me." I've noted the likes of Karl Pilkington in the UK doing this sort of "double subject" structure. "I'm a nice guy I am", "He's a good guy him", etc... I cannot provide any more particular examples but I have seen this enough to associate it with British English, perhaps northern in particular. I've searched to find what this might be called but can't find any other discussions of it. Any insight?


Operation overloading for namespaced classes

So let's say I have the following class :  namespace Example {     class Bar {}; }   Now in case I want to overload the operators for the class Bar, should I do :   namespace Example  {     class Bar {};      ostream& operator<<(ostream& os, const Bar& b)     {/*..........*/} }   or should I do :  namespace Example {     class Bar {}; }  ostream& operator<<(ostream& os, const Example::Bar& b) {/*..........*/}   If I'm supposed to do either of the above, please post the explanation for why it should be done that way.  P.S. /*.....*/ simply means the body of the functions(omitted for simplicity)


De Rham Cohomology of the tangent bundle of a manifold

I would like to compute the de Rham cohomology of the tangent bundle $TM$ of a manifold $M$. It seems to me that we can just homotopy each fibre to a point, and that this would give a homotopy equivalence between $TM$ and $M$. Since de Rham cohomology is a homotopy invariant, this would imply that $H^*_{\text{dR}}(TM) \cong H^*_{\text{dR}}(M)$.     Is it always true that the tangent bundle of a manifold is homotopic to the manifold itself by the homotopy of each fibre with a point?


Install translation files that should survive updates

Someone prepared me a .po and a .mo file for a commercial theme we are using.  How can I install them in such a way that future updates won't destroy them?  Putting them into the languages folder was a bad idea. Putting them into the theme folder will make theme updates problematic. I'm thinking of creating a custom plugin that contains the translations. Better ideas?


Cannot find amsmath amstools package even though the doc used to compile

This is from a document that used to compile. I want to use it as a template as it was a really good template.  However when I press compile it says that it cannot find the amsmath or amstools packages. I have included a screenshot.  Furthermore, I cannot see how these packages can be installed.


What does "ww35" or "ww20" mean in a URL or domain, like in ww35.mydomain.com?

What does "ww35" or "ww20" mean in a URL or domain like, in ww35.mydomain.com?  What is they used for?   Why when I visit some page using these, receive a message "This IP has been banned". Which IP is banned? The sites' IP or mine? (I mean the IP my ISP provider asign to my modem) This message is only in an specific URL's with ww35. and ww20. URL's and both are the URL resulting of a redirected domain with a common www. prefix. Is th same question, this second part of question is my concern about if this prefixes are in potentially dangerous sites to my PC.  IS a diferent question of wwws with an additional "s" because it was specific with its the relation with the protocol https, I want to know if is really the same 3 w's or 2 w's and the difference between both if it exists.


Book series about aliens who put "caps" on people to control them

I remember reading a series when I was around 7th or 8th grade about aliens who had taken over Earth by putting metal caps on people when they were "entering adulthood" to control them (not direct control, but it would keep them from rebelling). There was a faction of people who able to escape and had fake caps and would save teens who were about to be capped.  The main protagonist was a teen boy who was a boxer (or training to be a boxer or something). The aliens would hold tournaments for the humans and whoever won would be "worthy" to serve as personal slaves to the aliens.     The protagonist won and was able to get inside to try and learn more about the aliens from the inside.


Errors in Apex Class - List has no rows for assignment to SObject

I want to add an apex message inside of my method that will showup if query returns a null value. Here is a bit of the code that includes query.  AccName = [Select Name, Customer_Account_Number__c               from Account where Customer_Account_Number__c =:uano limit 1].Name;      if (AccName == Null) {          ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.Warning, ''));                 system.debug('Empty string');      }      else{system.debug('found acc name ');}   unfortunately when a user types in a wrong number an error message in a salesforce pages shows up and I'm trying to avoid that. What could a best solution for that be ?


Prove that $F_n < 2^n$ for every $n \geq 0$ - Mathematical induction

The Fibonacci sequence $0$, $1$, $1$, $2$, $3$, $5$, $8$, $13$, ... is defined as a sequence whose two first terms are $F_0=0$, $F_1=1$ and each subsequent term is the sum of the two previous ones: $F_n = F_{n-1} + F_{n-2}$ (for $n \geq 2$). Prove that $F_n < 2^n$ for every $n \geq 0$.   My solution:  Basic step: $F_2=1 < 2^2$  Inductive step: Suppose $F_i<2^i$ for $i \leq n$. Show that $F_{n+1} < 2^{n+1}$.  $F_{n+1}=F_{n} + F_{n-1} < 2^n + 2^{n-1}<2^{n} + 2^{n} = 2^{n+1}$.   Do I have the right to use mathematical induction that way in the proof? If so, can you explain why compared to the usual definition of induction?


If $\lim\limits_{x \rightarrow \infty} f'(x)^2 + f^3(x) = 0$ , show that $\lim \limits_ {x\rightarrow \infty} f(x) = 0$

If   $f : \mathbb{R} \rightarrow \mathbb{R}$ is a differentiable function and  $\lim\limits_{x  \rightarrow \infty} f'(x)^2 + f^3(x) = 0$ , show that $\lim\limits_{x\rightarrow \infty} f(x) = 0$.  I really have no clue how to start, I tried things like MVT and using definition of derivatives but I really can't figure this out.


ERROR pj_get_spheroid_defn EXTENSION POSTGIS2_96 POSTGRES-9.6

I recently had this error, and surely other people also are going to have when they update the POSTGIS and POSTGRESQL, so I want to share the solution.  OS: CENTOS 6 (x86_64)  Installed: postgresql-9.6 from   yum install postgresql96-server postgresql96   installer: postgis2_96  yum install postgis2_96   problem/error when start to enable POSTGIS using psql or pgAdminIII :  psql (9.6.3)     postgres=# \connect SANTANDER     You are now connected to database "SANTANDER" as user "postgres".     SANTANDER=# CREATE EXTENSION postgis;     ERROR:  could not load library "/usr/pgsql-9.6/lib/postgis-2.3.so": /usr/pgsql-9.6/lib/postgis-2.3.so: undefined symbol: pj_get_spheroid_defn   I checked the PROJ version:  $ yum list installed | grep proj  proj.x86_64        4.7.0-1.el6                           @epel   the problem is solved upgrading the PROJ  $ yum upgrade proj Updated:   proj.x86_64 0:4.8.0-2.rhel6


How to approximate acceleration from a trajectory's coordinates?

If I only know $x$- and $y$- coordinates of every point on a trajectory without knowledge of time information, is there any way to approximate Cartesian acceleration angle at each point? Time interval between every two points is very small, ~0.03 second.


Using stainless steel utensiles on aluminum

I roast vegetables in aluminum baking pan. To remove these, as they do get crispy, I use stainless steel spatula.  I have noticed slight scratches on the baking pan.   Will this affect baking in the baking pan? Does this matter other than esthetics?


What is a gerund? A noun or a verb? 'His smoking upset me’

I've been studying the Huddleston and Pullum book for four months now. So far only one thing confuses me: the identity of gerund. Is it a noun or a verb?        His constant smoking upset me.  smoking seems  noun because of adjective constant.   Him/His constantly smoking upset me. smoking seems to be verb because of adverb constantly.   Him/His smoking cigars upset me. smoking seems to be a verb because of object cigars.      "His smoking upset me." So is this smoking gerund a noun or verb? Because there is no differentiation, is it both verb and noun? Maybe it's new word category?  Also his seems to be both  sometimes a subject and at other times a possessive determiner. Is that correct?


variable assignment in python and references

My understanding of variable assignment in Python is that when you do a = 1, the interpreter allocates some memory, stores the number 1 and then a is a reference to that number. Why does the following happen:  a = 1 b = 1 a is b #True   On the other hand:  a = 1. b = 1. a is b #False   What is going on? I expected both statements to evaluate to False


How does one define the entropy of a natural network (say for example, a river network, or a morphological skeletal network of a lake in the figure below) ? For example, the following report suggests defining it in terms of a topological diameter. But,again it involves defining the generator of the fractal network.  Ref:


How to move the camera while in camera view?

I want to know how to move the camera along my view, so I can render the point where I want. I have seen many people moving the camera along their view and they are in modelling tab. I don't know whether there's an option to move.


Recent events have made it clear to me that after giving up attempts to create a friendly environment years ago, Stack Exchange now prioritises  over everything else. This is not an environment to which I wish to contribute.  Unfortunately, the instructions for deleting accounts appear to be out of date. They say there is a link "Edit Profile & Settings" on the "profile page" or on the "user page". Presumably that would be the page that I can reach by clicking on 'my' icon when logged in. There is no such link there, nor anything similar, and I can't find anything better.  So how can one delete one's profile nowadays?


Given the curve $y = 2 x ^3 + 3 x ^2 − 36 x$ on the interval $− 1 \le x \le4$ , find the absolute minimum?

I know I have to find the first derivative which is $y'=6x^2+6x-36.$ Then I set it to $0.$ Which I got $0 = 6(x^2+x-6)$ and then $x=-3$ or $x=2.$


How to search for a particular file or all files from a graphical interface

Is there some graphical tool to search for a particular file or all files of that format from a folder and many sub-folders and which takes a query like *.txt and the path of the partition on which the folder with many sub-folders is located and output the result?


Proving that $e^{\pi}-{\pi}^e\lt 1$ without using a calculator


Can we sure that a bounded linear operator is compact just having a condition on the range?

The problem is the next:  Suppose that $A\in B(X,Y)$, $K\in K(X,Y)$, where $X,Y$ are Banach spaces. Show that, if $A(X)\subset K(X)$, then $A\in K(X,Y)$.  Here $B(X,Y)$ stands for the set of all bounded linear operators from $X$ to $Y$, and $K(X,Y)$ stands for all compact operators from $X$ to $Y$.  I've tried some ways to prove it, but none of them successfully. What I reach to prove is the easy case, when $K$ is a surjective operator, because in this case$Y$ is finite-dimensional and every bounded linear operator on a finite-dimensional space is a compact operator. Then, I remember (but I'm not sure if it is true!) that a compact operator is one-to-one if and only if it is not surjective, so if we suppose that $K$ is not a surjective operator, then $K$ is one-to-one. I've tried to use this property but I could conclude nothing.  Any help or hint is well received.


How do I round a number in js with negative precision like in Excel round function

I am trying to round the value from 8904000 to 8900000 is there any possible way to change this using Math.round. example  in MS Excel   =round(8904000,-5); ANS: 8900000         I tried the code below but Math.round does not take a second argument  Math.round(8904000,-5); ANS: 8904000   In short I want to round of the number to the nearest 100,000 number  So that  5300*56*30= 8904000 becomes 8900000


Which of the following is considered correct? ". . . where I was at age five." or ". . . where I was at age 5."


i am having lenovo g505s laptop with windows7(not preloaded),i want to install ubuntu alongside with windows 7, but it is not showing install alongside option, how do i get that? it is not detecting my os. i went from bios menu, theres no option like disable secure boot, boot mode :Legacy            UEFI  i have tried enabling both alternately still didnt worked . Need Help,  I Love Ubuntu ;


attempt to invoke virtual method on a null Object (NullPointerException)


I have set few aliases in .bashrc file. I need those aliases most of the time, but sometimes I need to run those command without options set in that particular alias.  How to not execute alias command?


Solve the Diophantine equations: $|a^2 -2b^2|=1$?

Find all integers $a$ and $b$ such that: $$|a^2 -2b^2|=1$$ The solutions to this equation are related to the units of the ring $\mathbb{Z}[\sqrt{2}]$.


Currently, to see console.log() entries from StackSnippets, you need to open your browser console, and make sure it's recording from frames. Things could be a lot simpler if you would add a console to the snippets. Maybe something at the bottom of the snippet.  This could be done by overwriting the default console.log function with a custom one that both writes to the browser console (keep a reference to the original function), and also writes to the snippet's console.  EDIT: And perhaps also show errors thrown in this console.


How to decode an (unknown) Unicode character to its assigned name (description) on the command line?

Given an unknown Unicode character, how can I tell the (ASCII) name of that character using Linux cmdline tools only ?   I'm looking for a more elegant way than fetching the Wikipedia page on the Unicode block, grepping the HTML oder wikitext source for the charcter code and finding the description next to it.


Prove that $(x-1)^2\mid f(x)=nx^{n+1}-(n+1)x^n+1$  We can prove this easily by showing $f(1)=f'(1)=0$. But is there a way to solve this problem without using calculus?


Will a PC's passive ability function while they are polymorphed?

Let's say a Gnome bard polymorphs themselves into a triceratops, then has to make a strength check to bust through a door frame. Would they be able to add jack of all trades to said check? As it is a passive ability?


When I use sudo apt-get update, I get an error:  $ sudo apt-get update E: Malformed entry 56 in list file /etc/apt/sources.list (URI parse) E: The list of sources could not be read.   I've found the line throwing the error:  deb http;//archive.canonical.com/ xenial partner   Any help would be greatly appreciated.


I am running Ubuntu 12.10 alongside Windows 7 I can connect to the internet using ethernet but cannot detect any wireless networks. When I use Windows 7 I can connect fine. Any help would be greatly appreciated. The output for lspci -v | grep -iA 10 network was:  02:00.0 Network controller: Broadcom Corporation BCM43142 802.11b/g/n (rev 01) Subsystem: Dell Wireless 1704 802.11n + BT 4.0 Flags: bus master, fast devsel, latency 0, IRQ 11 Memory at c0500000 (64-bit, non-prefetchable) [size=32K] Capabilities: <access denied>   lsmod:  Module                  Size  Used by joydev                 17457  0  snd_hda_codec_hdmi     32007  1  snd_hda_codec_conexant    57842  1  rfcomm                 46619  12  bnep                   18140  2  parport_pc             32688  0  ppdev                  17073  0  lp                     17759  0  parport                46345  3 parport_pc,ppdev,lp coretemp               13400  0  kvm_intel             132759  0  kvm                   414070  1 kvm_intel ghash_clmulni_intel    13180  0  cryptd                 20403  1 ghash_clmulni_intel dell_wmi               12681  0  sparse_keymap          13890  1 dell_wmi psmouse                95552  0  dell_laptop            17369  0  dcdbas                 14438  1 dell_laptop microcode              22803  0  snd_hda_intel          33491  3  snd_hda_codec         134212  3        snd_hda_codec_hdmi,snd_hda_codec_conexant,snd_hda_intel snd_hwdep              13602  1 snd_hda_codec uvcvideo               76749  0  videobuf2_core         32851  1 uvcvideo videodev              120309  2 uvcvideo,videobuf2_core videobuf2_vmalloc      12860  1 uvcvideo videobuf2_memops       13368  1 videobuf2_vmalloc snd_pcm                96580  3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec snd_seq_midi           13324  0  snd_rawmidi            30512  1 snd_seq_midi wmi                    19070  1 dell_wmi btusb                  18334  0  bluetooth             209199  22 rfcomm,bnep,btusb snd_seq_midi_event     14899  1 snd_seq_midi mac_hid                13205  0  snd_seq                61521  2 snd_seq_midi,snd_seq_midi_event snd_timer              29425  2 snd_pcm,snd_seq snd_seq_device         14497  3 snd_seq_midi,snd_rawmidi,snd_seq rts5139               356158  0  snd                    78734  16   snd_hda_codec_hdmi,snd_hda_codec_conexant,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,s    nd_rawmidi,snd_seq,snd_timer,snd_seq_device i915                  520519  3  drm_kms_helper         46784  1 i915 drm                   275528  4 i915,drm_kms_helper i2c_algo_bit           13413  1 i915 soundcore              15047  1 snd snd_page_alloc         18484  2 snd_hda_intel,snd_pcm serio_raw              13215  0  lpc_ich                17061  0  mei                    40690  0  video                  19335  1 i915 r8169                  61650  0    iwconfig:   eth0      no wireless extensions.  lo        no wireless extensions.   rfkill list all  0: hci0: Bluetooth Soft blocked: no Hard blocked: no


Create a text file using user input from a batch file

Is it possible to write a batch file that will create a popup window for the user to input some specific information, and place that information into a text file? The text file should already have some text in it but I just want a couple lines to have input from the user. This is what the text file should look like:  PARTSN="USER INPUT1" PART=blahblah WORKSTATION=blahblah USERID="USER INPUT2" SIZE=blahblah   Where it says "USER INPUT1,2" is where I want the information from the user placed.  Any help would be great!


How to use Internet from Windows PC to Android tablet?

I am using Windows 7 PC and Samsung Galaxy Tab 2 p3100 tablet. I use internet mostly on my PC. But i also want to use on my tablet, but i don't know how..  "I don't want to use any router or something."  So, without any router is there any way to use internet from my PC to tablet? I just know how to use internet on PC from Tablet. (ie, by USB Tethering)  Thanks.


What does  signify when using Vim LatexSuite?

I have a LaTeX editing environment that does some assistive stuff such as auto-indenting, closing parentheses, etc.  However, one of the things that it does is unknown to me, and is difficult to search for. If I type an empty set of braces, it replaces them with  {}<++>   If I type two empty sets, for example when I'm setting up a fraction \frac{}{} what I actually get is  \frac\left\{ } \right\}<++>}<++>   Is this a problem? What does <++> do?  Edit: This is using


Is there any advantage of using size_t over int in this code?

#include <iostream> #include <array>   int main() {     std::array myArray { 7, 3, 1, 9, 5 };       // Iterate through the array and print the value of the elements     for (int i{ 0 }; i < myArray.size(); ++i)         std::cout << myArray[i] << ' ';       std::cout << '\n';       return 0; }  It is stated that There is a signed/unsigned mismatch. The size() function and array index parameter to operator[] use a type called size_type.  Our loop counter/index (variable i) is a signed int. Therefore both the comparison i < myArray.size() and the array index myArray[i] have type mismatches. I understand the statement, but what is the consequence of this mismatch? My IDE (VS2019) neither gives a error nor a warning. Are there any performance benefits from using std::size_t in place of int in this code? #include <array> #include <cstddef> // std::size_t #include <iostream>   int main() {     std::array myArray { 7, 3, 1, 9, 5 };       for (std::size_t i{ 0 }; i < myArray.size(); ++i)         std::cout << myArray[i] << ' ';       std::cout << '\n';       return 0; }


I am trying to measure the current flows over time of a Particle Argon from the initial boot, through normal processing then going into deep sleep mode. My code runs great on its own and does exactly what I want, repeatedly when I wire things up like in Scenario A.  However, Scenario B I am using a Siglent multimeter to do the current measurements and the Argon fails after the initial power on, resets, and trys again.  This process repeats indefinitely.  The power amp is set to deliver a max of 1A which is well beyond what the Argon would pull right at power up. Is my multimeter "faulty" or is there something I am not considering in my setup to make this measurement successfully?  I realize the Siglent SDM3055 is not the highest end multimeter, but surely it is made well enough to do this type of test?  Any thoughts would be greatly appreciated. Note same power supply and setting used in both scenarios.


Creating a 5x5 poylgon in ArcGIS with a predetermined center with coordinates X, Y

I need to build a polygon (5x5 km) centered on a coordinate X,Y. I want to use this 5x5 square for an eventual clip.  How should I proceed in ArcMap?


Using ion radiation to make electricity?

Is it possible to capture the ion radiation from a nuclear source and make electricity from it? I always thought it was possible, but never looked into it? Is this what a beta voltaic battery does?


How to determine $\int x^2 e^{-x^2}\mathrm dx$?

I was wondering how to determine $$\int x^2 e^{-x^2}\mathrm dx?$$ I tried to move the exponential into the integrator, and apply integration by parts, but that will make the integrand more complicated. Thank you!


Counting two ways, $\sum \binom{n}{k} \binom{m}{n-k} = \binom{n+m}{n}$

prove by counting two ways:    I though to prove the right hand side I would say: Let n represent a number of boys and m a number of girls. We want to choose a group of n from boys and girls. But for the left hand side I want to keep the variables m and n girls and boys. But I don't know what k will be. Suggestions?


What do free and leading variable mean and how can they be found?

Can someone please explain what the leading variable actually means in a matrix as well as what the heck is a free variable and where can it be found? Thank you!! I am so lost in this course


What is the difference between -all and ~all in a DNS SPF record?

I've found that our current DNS SPF record uses the ~all keyword, but in most examples I've seen -all used.    What's the difference between the two?


I'm pretty new to blender, and i wanted to try to render something pretty simple, so i made a house. But the problem is, that when i try to apply my seamless texture to roof, it is showing/acting like color. I really don't know why, because the texture is ok. I have tried to figure it out using nodes, but i didn't came up with a solution...


Checkout branch does not revert my changes

I created a new local repo with 1 file in it.  + foo |- .git |- foo.txt (4 bytes)   I now modify foo.txt and stage my change. Afterwards I execute git checkout -b new-branch. Shouldn't my new branch have the state and files of the upstream-branch before my temporary changes?  Here is an example:  #-------setup git repo with 1 file and foo.txt (4 bytes)------- $ git init .                   Initialized empty Git repository in foo/.git/ $ echo 1234 > foo.txt $ git add . $ git commit -m 'first message' [master (root-commit) 4aa4409] first message 1 file changed, 1 insertion(+) create mode 100644 foo.txt  #-------modify foo.txt, stage and create new branch------- $ echo 123456789 > foo.txt $ git stage foo.txt  $ git checkout -b new-branch Switched to a new branch 'new-branch' $ cat foo.txt 123456789     #<---- I expected 1234 here


How to handle JavaScript being disabled in AngularJS

AngularJS is dependent upon JavaScript being enabled. This means that if someone visits an application or website built in AngularJS it will not render properly.  What are common conventions used to handle visitors with JavaScript disabled when using AngularJS?  Please explain why this is the case?  Included in the problem is the case of handling angular JS directives and {{data_bindings}}. So that the data does not show when the page cannot render the page.


I'm trying to find speed of network interface using file-descriptor. It's easy to do it for ethX, just calling cat /sys/class/net/eth0/speed. Unfortunately this method doesn't work with wireless interface. When I call /sys/class/net/wlan0/speed I get error: invalid argument.   So, do you know any /sys/class/net/eth0/speed like analog for wlan interface?


How the money is paid to the IPL players?

If a player is auctioned for Rs. 14cr and he played only 3 match will he be entitled to get his entire fees or he will be paid on a prorata basis for e.g no of match played.


ResultSet instance is not null, but next() call throws NullPointerException

I have two cursors which are used to display details in UI.   headerCur = (ResultSet) cstmt.getObject(4); serialCur = (ResultSet) cstmt.getObject(5);    When the user enters a wrong value, it goes to serialCur.next().  while (serialCur.next()) {     // ... }    However, it throws a NullPointerException.  I have logged and found that the serialCur is not null, but the next() call throws null pointer exception anyway.  How is this caused and how can I solve it?


Can blender render on multiple graphics cards?

I have a PC which has 2 CPU's in the mainboard, 40 GB RAM and 3 Graphics Cards. Can Blender render for example one frame on all gpus at the same time? And generally: is it possible to render on cpu and gpu at the same time?


I want to use an old drive as a secondary hard drive without reformatting. But this old hard drive contains my old Vista installation which takes up gigs of space.  I tried changing ownership and it works to some extent but I can not delete anything in Windows/System32 folder.  Is there an easy way to change permissions so I can delete everything?    The solution is to use Takeown as Wil suggested and use cacls to take full control of the files. Since cacls doesn't seem to be recursive, I fired up cygwin and ran this command to recursively change all the files:  for d in $(find directory-of-interest -type d);do   cacls $d'/*' /e /G username:F; done   where directory-of-interest is in my case /cygdrive/g/Windows and username is my username.  I had to manually run it on directories that had spaces in its name. But after all this, I can now delete the directory. Warning: it seems to me that cacls can potentially royally screw things up if improperly used.


Does male or female DNA contain more information?

I wonder if the male or the female DNA contains more or less information than the other?


Why can't we make CON, PRN,Null folder in windows?

When i make new folder and rename it to nul it says The Specified device name is invalid.   then I searched which are the other folders we can't make, and get names con, nul, prn ?   what are these names stands for ? and why can't we make folders with these names ?


I'm running a nightly build, will apt-get upgrade keep me current?

I'm trying out the xenial nightly, and I'm wondering if I have to download a new nightly once in a while to keep up to date, or if running sudo apt-get dist-upgrade will keep me current.


I am adding a number of strings together to create a linestring but as such I need spaces between the initial XY values and the end XY values, plus a comma in between the two halves.  Should result in LINESTRING(97763.88319  434314.9609 , 97620.90369  434175.115) but the space is not recognized like it would be in excel I don't want to make another attribute which only holds a space to then include it as a variable.  This is the expression I used:  concat("LINESTRING(", "X", " ", "Y", " , ", "newX", " " , "newY")


Computer want to install Ubuntu when I restart after I completed installation

It is very strange,  I just installed Ubuntu 16 on my computer, and at the end of the installation, the system says that I need to restart my computer. When I do it, I get back to the black screen that asks me if I want to try Ubuntu or if I want to install it. I'm stuck in an infinite loop.  However the first time I did the installation, I was able to do the crypted one, protected by password. Now I can't. Also, sometimes the system says that some files already exists, which certainly come from the first installation, and that it may cause issues.


What "exactly" happens when someone turns to the Dark Side?

When I saw the original Star Wars saga as a kid, the concept of the Dark Side imprinted in me was quite simple. You did a bad thing, so you're a bad person so you go to the Dark Side and keep doing bad things.  Now, obviously this doesn't hold true in reality. In my mind it is perfectly reasonable for Luke to kill the Emperor and Vader and then just flee the Death Star and rejoin the Alliance. After all they are at war, those are enemy officers that have captured him and are taunting him by threatening with death of all loved ones and the whole operation was intended to kill the Emperor anyway.   The same would hold true for Anakin. He could have killed Mace Windu to save the Chancellor and Padme but that doesn't mean he's going to then go mad and kill all Jedis including children. It doesn't add up from a merely psychological point of view. He had a set of objectives and that made him want to keep the Chancellor alive (quite valid by the way, Mace Windu is quite clumsy on that) but just after killing him he goes into "Yes master I'll do whatever you say" which from a normal point of view will NEVER ever make sense.  In both cases it seems like the assumption is once you use the Dark Side you completely turn to the Dark Side and become a different person that you were before. That would be coherent with Anakin "dying" and Vader being born.  Is that the way the Dark Side works? Is there any canon information about what happens when someone turns to the Dark Side? Specifically to whether they become a different person or how he or she actually changes?  Note: Vader is angry after he finds out Padme is dead, even though he's already turned.  Example of what I mean. In Buffy they explain how people that turn into Vampires lose their soul and it's taken over by a demon, and thus they are, in all effects, a different person with their memories.


Convergence of $\sum _{k=1}^\infty (1-\frac{1}{k})^{k^2}$

Found the alternative form: $\sum _{k=1}^\infty ((1-\frac{1}{k})^{k})^k$. Tried various criteria, no luck so far.


Calculations with operators - Proof: Equation of Operators

I have a problem in Quantum mechanics 1 with Operators. I have to prove the following equation. I tried it for about 4 hours without any result:  Condition: $[[\hat A,\hat B],\hat A]=[[\hat A,\hat B],\hat B]=0$  $$ e^{\hat A} \hat B = (\hat B + [\hat A,\hat B]) e^{\hat A} $$   Info: $e^{\hat A}=\sum\limits_{n=0}^\infty \frac{(\hat A) ^n}{n!}$  Maybe you could help me?  I've done these steps:  $$ [e^{\hat A}, \hat B] = [\hat A,\hat B] e^{\hat A} = e^{\hat A} [\hat A,\hat B]  $$  $$ \sum\limits_{n=0}^\infty \left( \frac{(\hat A)^n}{n!} \hat B - \hat B \frac{(\hat A)^n}{n!}\right) = \sum\limits_{n=0}^\infty \left( \frac{(\hat A)^n}{n!} \hat A \hat B - \frac{(\hat A)^n}{n!} \hat B  \hat A\right)  $$  But now I don't know how to go on...


I'm creating a Java application, and when creating an interface to use with an ADT, it finds the need to initialize a random number as an ID number.  public class StackFullException extends RuntimeException {     private static final long serialVersionUID = 1L;     public StackFullException(){}     public StackFullException(String message) {         super(message);     } }   I'm curious as to whether leaving this out will impact anything consequential about my program and if so, how to avoid it.


simulating linux's "cd" command in python , and persist the directory change after the program exits

i used the following code so to persist the directory change after the program exits but the drawback is that it opens a new sub shell , so each tim a run it a new subshell is opened   import os, subprocess newpath="/usr/local/www/nginx" oschdir(newpath) subprocess.call(['bash'])   is there a wayout , i want to do this in FreeBSD 10.1,python3 , irrespective of the shell .  Is there a way out.


Why do we have to apply location, scale, rotation onto a mesh and what are its consequences?

I'm asking as everyone in tutorials apply it onto the mesh but they don't explain it properly. It seems to me that it causes some problems. But I still didn't get why it causes problems if I don't apply location, rotation, scale to a mesh.


Is the differentiation operator an open mapping?

Consider the vector spaces $C([0, 1])$ and $C^1([0, 1])$ with norm, \begin{align*} \displaystyle \|f\|_\infty=\sup_{x\in [0, 1]}|f(x)|, \end{align*} and let $T:C^1([0, 1])\to C([0, 1])$ the operator given by, \begin{align*} \displaystyle Tf=f'. \end{align*} Is $T$ defined this way an open mapping? If it's, how to prove it?


Are there any repositories of "killer slides" for Beamer?

I used to work as a consultant and have been spoiled with nice looking slides. For instance, being able to create slides that have 2, 3, or 4 graphs (perfectly positioned and with nice headers!) at the click of a mouse button via macros.  Similarly, there are many other kinds of word slides that had multiple columns, etc. that would be nice to recreate as well as objects like "main point" boxes at the bottom that summarize a main point and ways to add a transparent highlight to any part of the screen.  Is this kind of functionality far beyond anything that LaTeX presentations can do or is there an archive somewhere of code for making more intricate presentations?


Let's forget how it is used or what it might imply , because why , is why? (?) Regardless am I not correct." Why, thank you" makes little sense to use unless you are asking why someone is thanking you. let's keep it real , I don't think there is another language that uses such , so  commonly.It is not correct....it makes no sense.  Am i the only one here that feels this way?


I've got this meta SoapHeader, SoapDocumentMethod...how can I know when they are executed?, before the method is executed or after it is executed? and where is the method that this metas are executing? what name it has?  [SoapHeader("AgentInfoHeaderValue")] [SoapDocumentMethod("http://www.example.com/xml/andromeda#WORK", RequestNamespace = "http://www.example.com/xml/someapi", ResponseNamespace = "http://www.example.com/xml/someapi",      Use = System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle = SoapParameterStyle.Wrapped)] [return: XmlElement("return", Namespace = "", IsNullable = false, DataType = "base64Binary")] public byte[] WORK([XmlElement(Namespace = "http://www.example.com/xml/someapi", DataType = "string", Form = XmlSchemaForm.Qualified)] string guid, [XmlElement(Namespace = "http://www.example.com/xml/someapi", DataType = "base64Binary", Form = XmlSchemaForm.Qualified)] byte[] data) {    //some actions }


How to quickly move current window to another Task View / desktop in Windows 10?

Windows 10 introduced Task View - the ability to have multiple virtual desktops. When I am in a window on Desktop 1, what's the quickest way to move it to Desktop 2?  Currently, I need to enter the task switcher (icon in the Taskbar or Win + Tab), find the window, and drag & drop it between desktops. It is inconvenient. Is there a quicker way?


I have tried all solution. installed ppa manager, run the sudo apt-get update command but still its not working. It shows the pop-up for update and when i click ok, it says installation of untrusted files. And if i press ok it gets closed. what to do. i m using asus x 550cc


Why Autoboxed Integer isn't incremented inside the caller

Consider the code:  static void incr(Integer n) {     n++; }  public static void main(String args[]) {    Integer n = 66; // Autoboxing     incr(n);     System.out.println(n); }   The above program outputs 66. I expected it to print 67 and here is why. Boxing a value converts the primitive value to an object, right. In case of objects, Java passes the pointer to the object to a called function, that's incr in the above example. incr() increments the value in the memory cell passed to it. So, the change in value must occur in n too. Now please tell me, what am I missing?


Why does Ubuntu keep asking for my gmail password?

After upgrading to 13.10, I am now getting a prompt for my gmail password every time I log in. There is no indication as to which service or application needs this information. If I enter the correct password I'm told it is incorrect. My gmail account does not use two factor authentication. The problem has only started after an upgrade from 13.04 to 13.10.  How can I prevent this prompt appearing, and/or what is doing the prompting?


Php function to prevent SQL injection.  I am developing a Wordpress project wich I require users to insert some data of their need.  I have created new tables in database for my use, though, now I need to be safe and protect from SQL injection.  For this use I have created following var.  function sql_escape($var){ if(is_string($var)) { $result = strip_tags(addslashes(str_replace(array('SELECT', 'select', 'DELETE', 'delete', 'INSERT', 'insert', 'JOIN', 'join', 'CREATE', 'create', 'UPDATE', 'update', 'FROM', 'from', 'WHERE', 'where', '*', '=', '+', '-', '<', '>'), '...', $var))); return $result; }  if( is_numeric($var) || is_float($var) ){     $result = $var;     return $result; }}   Do you think this could be enough ? Thanks everyone for support.


Increase thickness only on specific parts of a 3D model

I am trying to improve the model shown below. As it can be  seen, the cloak of the model contains some holes. I tried to apply the Solidify modifier, but in this case the thickness of the whole model is affected (i.e. the neck of the model becomes to wide). Is there any way to fill these holes?


Suppose $\theta \neq \frac pq * \pi$. Show ${\{e^{in\theta} : n \ \epsilon \ N}\}$ is dense in $S^1=\{x + iy: x^2 + y^2 = 1\} \subseteq C$

Essentially, I need to show that e^inx is dense in the complex unit circle for irrational angle x. I'm not sure how to go about this but I think I need to show that between any two points on the unit circle, we can find some e^inx.


If I have the following sentences, which version is correct:   This chapter provides.... or This Chapter provides....   Note the capitalisation of 'c'.   Chapter 1 provides.... Chapter One provides...   Note the use of numbers   This model was discussed in Chapter One This model was discussed in chapter one This model was discussed in Chapter 1 This model was discussed in chapter 1   Note the use of capitalisation and numbers in the last part of the sentence.  Many thanks.


Why does my posterior distribution have probability values greater than 1?

I'm attempting to learn Bayesian modelling with PyMC, so I have been going through Cam Pilon Davidson's Probabilistic Programming for Hackers. I literally copied his code from chapter 1 and used my own storm data. Here is the  of my code.  My problem is with the posterior distributions. One of them returns probabilities over 1. Or are they not actually probabilities? Should I be using a different alpha for my exponential distributions? Am I asking the right questions?  I'm not a heavy math person, so I may have a fundamental misunderstanding about what is going on here...  Thanks for any help!


Let $f$ be a irreducible polynomial in $\mathbb{F}_p[x]$ of degree $n$.  Why are there $p^n$ elements in the quotient field $\mathbb{F}_p [x]/ (f)$  I am having some difficulty convincing myself this is true.  Any help or insight is deeply appreciated


Comment Package: Problem when using German Special Character "ß" (Similar to "ss")

I am preparing a bilingual document and using the  to distinguish between the two languages.  When I use the special character ß in a comment environment then I get an error message (Undefined control sequence.) although I use \usepackage[latin1]{inputenc} correctly.  Outside of the comment environment the character works fine.  The document class seems not to matter - I have the problem with scrbook and book.  \documentclass[]{scrbook}  \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc}  \usepackage[     english,     ngerman]         {babel}  \usepackage{comment}  \includecomment{Version-DE} \excludecomment{Version-EN}  \begin{document} ß % <-- no problem here  \begin{Version-DE} Version-DE ß % <-- big problem here! \end{Version-DE}  \begin{Version-EN} Version-EN \end{Version-EN}  \end{document}   I am not sure what tags to use here...  For Future Reference  I have found some other packages that maybe could be an alternative:    (recommended by the author of the tagging package Brent Longborough, see )  --> seems to be pretty robust and flexible so far     (extra "s")       Here's all the packages of this kind (conditional typesetting) on CTAN:


How to reach from Terminal 3 to Terminal 2 in Dubai airport

Good day.  I am going to take a trip from Sydney (SYD) to Yerevan (EVN) via Dubai (DXB). The first part of the flight is with Emirates (EK), the second part with Fly Dubai (FZ). In Dubai airport I should change terminals between 3 to 2. I would like to know how I can reach Terminal 2 from Terminal 3. And do I need a visa if I am not going to leave the airport?


Can you blind a Demilich/creature that has Truesight?

RAW, I don't see why you can't blind something with Truesight, but I feel like it shouldn't be possible. (Maybe vestiges of previous editions?) I wonder whether I've overlooked some basic rule.


Where are .exr files listed in Properties dropdowns in Blender?

city.exr, courtyard.exr, forest.exr, interior.exr, night.exr, studio.exr, sunrise.exr, sunset.exr are shipped with Blender 2.92 and courtyard.exr wants to load by default into a simple refraction construct--it's visible here in the area below the UV skydome I set on top of the XY plane:  Before I discovered these samples in the Shading top-screen tab, I think I encountered the list of same .exr names elsewhere in the side screen control panels (but I don't remember where). Therefore my question is where are these .exr files in Properties dropdowns and elsewhere in Blender?


Far away things (skybox cube) not showing up?

When making a little animation thing, I ran into a problem, the camera could not see the entire skybox. (a large cube with textures on it) As in the camera would not render the entire box. Here is a picture:   Can anybody help me? Essentially I want the camera to be able to see further.


Why does the compiler think this is a funcition?

I'm having trouble distinguishing the differences when initializing objects using constructors.  I've also read that Bjarne recommends the {} syntax but that it's mostly equivalent to the () syntax so I think that I understand that part.  The problem occurs on line 40 with Car b();.  #include <iostream> #include <conio.h>  class Car { public:     Car() // initialize car     {         std::cout << "Default constructor called" << std::endl;         ++carNumber;     }     ~Car() // destroy car     {         --carNumber;     }      static int getCarNumber() { return carNumber; };  private:     static int carNumber; }; int Car::carNumber = 0;  int main() {      // Equivalent     std::cout << "Car a{};" << std::endl;     Car a{};     std::cout << "Car d = Car{};" << std::endl;     Car d = Car{};      // Equivalent     std::cout << "Car e;" << std::endl;     Car e;     std::cout << "Car c = Car();" << std::endl;     Car c = Car();       std::cout << "Car b(); " << std::endl;     Car b(); // this line      std::cout << "CarNumber: " << Car::getCarNumber() << std::endl;     _getch();     return 0; }   This is the output of the program:  Car a{}; Default constructor called Car d = Car{}; Default constructor called Car e; Default constructor called Car c = Car(); Default constructor called Car b(); CarNumber: 4   I'm confused with "Car b()". I think the compiler is interpreting it as a funcition that returns a Car, but if that's the case I don't see where the function may be implemented (it should cause an error?").  I expected "Car b()" to call the default constructor I made but it doesn't.


I had a requirement that using the main method arguments we have to do operations like Sum,Subtraction,Multiplication... For example: If the input is java Compute 1 2 3 add the last argument should be taken as the input for Addition and do operation...  I have written follwing code for requirement but its is not going inside if condtion and execute the code..can any one help ... thanq    package com.project;  public class Compute  {  public static void main(String[] args)  {      int Last = args.length-1;     String method[] = {"add","sub","mul"};     if(args[Last] == method[0])     {         //System.out.println(method[0]);         int sum = 0;         for(int i=0; i < args.length-1; i++)         {             sum += Integer.parseInt(args[i]);             System.out.println("Sum is:"+sum);          }     }else if(args[Last] == method[1])         {             //System.out.println(method[0]);             int sub = 0;             for(int i=0; i < args.length-1; i++)             {                 sub -= Integer.parseInt(args[i]);                 System.out.println("Substraction is:"+sub);             }         }else if(args[Last] == method[2])             {                 //System.out.println(method[0]);                 int mul = 0;                 for(int i=0; i < args.length-1; i++)                 {                     mul *= Integer.parseInt(args[i]);                     System.out.println("Multiplication is:"+mul);                 }     } } }


How to calculate $\int \frac{1}{\sqrt{\sin x\cos^7x}}dx$? I found  a problem, but the link is not valid.


How do I understand the quantization of the total orbital angular momentum to values $l(l+1)\hbar^2$?

I understand why the angular momentum along a particular axis ought to be quantized to values $m\hbar$. This is because the rotation unitary operator should return to the identity after each rotation by $2\pi$ and angular momentum (along that axis), being the generator of these rotations is also then quantized accordingly.   But why is the total orbital angular momentum $L^2$ quantized? More precisely why is it quantized to values  $l(l+1)\hbar^2$.


In the following sentence can the first comma be replaced with a semicolon for smoother reading?     "An hour drifted by, and the lady, whose name was Arcey Pierre, called it a day."


I modeled my room using an Add-on called Archimesh to make more easily windows doors and so on when I finally modeled the room and rendered it I faced 2 problems which are:   I added a sunlight that passes through the window of the room there is light in the room however it is really dim and the glass material of the WINDOW is not transparent I watched how BlenderGuru made the material for the glass and mine still is solid despite the fact that light is coming through the room. The next problem is rendering I used the Cycles render engine to render the room and got a really grainy image in the sampler I tried increasing the render value to 1000 still looks like crap.


Why does string theory require 9 dimensions of space and one dimension of time?

String theorists say that there are many more dimensions out there, but they are too small to be detected.    However, I do not understand why there are ten dimensions and not just any other number?  Also, if all the other dimensions are so coiled up in such a tiny space, how do we distinguish one dimension from the other?  If so, how do we define dimension?


Would casting banishment on a Revenant permanently send it away to another plane?

In my campaign I'm being chased by a revenant and I'm about to reach level 7. I was thinking of taking banishment to cast on the revenant. The spell states that it brings creatures native to my plane back after a minute but if the creature belongs to another plane it goes there. So because the revenant is dead would it go back to the land of the dead?