I have a system verilog module as shown in (a) which passes the testbench in (b) but this should be the case as this is not the correct implementation. Correct implementation shown in (c). I am missing anything or any suggestions. Also, in my testbench I will like to get rid of the correct JK flip flop code block as the current testbench is dependent on it.  a)  module jk_ff (input j, input k, input clk, output logic q);   always @(posedge clk)   case ({j,k})   2'b01 : q <= 0 ;  2'b10 : q <= 1 ;  2'b11 : q <= ~ q ;  endcase   endmodule   b)  `include "jk.sv"  module tb_jk();      // open fitness file     int passedFile;     reg j;    reg k;    reg clk;    wire q;     logic q2;     always #5 clk = ~clk;     jk_ff    jk0 ( .j(j),                   .k(k),                   .clk(clk),                   .q(q));     initial begin      $dumpfile("test.vcd");      $dumpvars;      // open file     passedFile = $fopen("passed.txt", "w");     //if(!passedFile) $display("error");     //if(passedFile)     //  $display("file opened");     //else     //   $display("couldn't open the file");        clk = 0;       j = 0;       k = 1;        #10 if(clk == 1 && j == 0 && k == 1 && q === q2) $fdisplay(passedFile, "%d", 1);          else $fdisplay(passedFile, "%d", 0);       #10 j = 0; k = 0;        #10 if(clk == 1 && j == 0 && k == 0 && q === q2) $fdisplay(passedFile, "%d", 1);             else $fdisplay(passedFile, "%d", 0);       #10 j = 1; k = 0;         #10;  if(clk == 1 && j == 1 && k == 0 && q === q2) $fdisplay(passedFile, "%d", 1);              else $fdisplay(passedFile, "%d", 0);       #10 j = 1; k = 1;        #10 if(clk == 1 && j == 1 && k == 1 && q === q2) $fdisplay(passedFile, "%d", 1);             else $fdisplay(passedFile, "%d", 0);         #10 $finish;           // close file       $fclose(passedFile);    end      always @(posedge clk) begin : good        case ({j,k})            2'b00 :  q2 <= q2;            2'b01 :  q2 <= 0;            2'b10 :  q2 <= 1;            2'b11 :  q2 <= ~q2;        endcase    end     always @(negedge clk) begin        if (q === q2) begin            $display($time, " pass q=%b", q);            //$fdisplay(passedFile, "%d", 1);        end else begin            $display($time, " fail q=%b q2=%b", q, q2);            //$fdisplay(passedFile, "%d", 0);        end    end endmodule   c)  module jk_ff ( input j,                input k,                input clk,                output q);     reg q;     always @ (posedge clk)       case ({j,k})          2'b00 :  q <= q;          2'b01 :  q <= 0;          2'b10 :  q <= 1;          2'b11 :  q <= ~q;       endcase endmodule   Earlier post

I have a testbench written for a JK flip flop. Below I have the correct circuit that passes the testbench and another circuit which passes the testbench as well. Is there something wrong with my testbench.  a) Correct JK flip flop  module jk_ff (input j, input k, input clk, output logic q);     always @ (posedge clk)        case ({j,k})           2'b00 :  q <= q;           2'b01 :  q <= 0;           2'b10 :  q <= 1;           2'b11 :  q <= ~q;        endcase  endmodule   b) Wrong JK flip flop but passes all test cases in the testbench  module jk_ff (input j, input k, input clk, output logic q);  always @(posedge clk)  case ({j,k})  2'b10 : q <= ~ q ;  2'b01 : q <= 0 ;  2'b11 : q <= 0 ;   endcase  endmodule   c) Testbench  include "jk.sv"  module tb_jk();      // open fitness file     int passedFile;     reg j;    reg k;    reg clk;    wire q;     always #5 clk = ~clk;     jk_ff    jk0 ( .j(j),                   .k(k),                   .clk(clk),                   .q(q));     initial begin     // open file     passedFile = $fopen("passed.txt", "w");        clk = 0;       j = 0;       k = 1;        #10 if(clk == 1 && j == 0 && k == 1 && q == 0) $fdisplay(passedFile, "%d", 1);          else $fdisplay(passedFile, "%d", 0);       #10 j = 0; k = 0;        #10 if(clk == 1 && j == 0 && k == 0 && q == 0) $fdisplay(passedFile, "%d", 1);             else $fdisplay(passedFile, "%d", 0);       #10 j = 1; k = 0;         #10 if(clk == 1 && j == 1 && k == 0 && q == 1) $fdisplay(passedFile, "%d", 1);              else $fdisplay(passedFile, "%d", 0);       #10 j = 1; k = 1;        #10 if(clk == 1 && j == 1 && k == 1 && q == 0) $fdisplay(passedFile, "%d", 1);             else $fdisplay(passedFile, "%d", 0);         #10 $finish;         // close file       $fclose(passedFile);    end endmodule ```


In real world example I have elemental composition data for groundwater, which is known to be coming from two sources. I have control data where all predictors are from source A and data where all predictors are from source B. I would like to be able to take an unknown water sample and predict what percentage is source A vs. B based on the elemental composition of that sample.   The problem is not obvious to me because it is not a categorical outcome, but rather the relative contribution of two potential categories - if that makes sense.  I've looked for similar questions but couldn't find one - be gentle! Thanks

I am thinking of building a model predicting a ratio $a/b$, where $a \le b$ and $a > 0$ and $b > 0$. So, the ratio would be between $0$ and $1$.  I could use linear regression, although it doesn't naturally limit to 0..1.  I have no reason to believe the relationship is linear, but of course it is often used anyway, as a simple first model.  I could use a logistic regression, although it is normally used to predict the probability of a two-state outcome, not to predict a continuous value from the range 0..1.  Knowing nothing more, would you use linear regression, logistic regression, or hidden option c?


I have two identical methods, one returns a Vector2 and the other a Vector 3. For convenience I'd like to not have different method names.   If I declare a variable like this  private Vector2 to;   ...and call a method that returns a type on it  to = getMousePosition();   I would like it to automatically use the Vector2 method, so it should return a Vector2. I don't know if this is possible however as when I try I'll get this console error  A member `DrawBouncingLine.getMousePosition()' is already defined. Rename     this member or use different parameter types   Which is reasonable enough. But I was wondering all the same.  The method I use looks like this  private Vector3 getMousePosition() {     Vector3 _mousePosition = new Vector3 (Camera.main.ScreenToWorldPoint(Input.mousePosition).x, Camera.main.ScreenToWorldPoint(Input.mousePosition).y, 0);     return _mousePosition; }  private Vector2 getMousePosition() {     Vector2 _mousePosition = new Vector2 (Camera.main.ScreenToWorldPoint(Input.mousePosition).x, Camera.main.ScreenToWorldPoint(Input.mousePosition).y);     return _mousePosition; }

Duplicate:     Maybe this is a very silly question but I don't understand why I can't declare two methods that have the same signature when they have different return types.  public class MyClass {     private double d = 0;      public double MyMethod()     {         return d;     }      public string MyMethod()     {         return d.ToString();     } }   I get a compile error that states that the class already defines a member with the same parameter types.  (Obviously the way I'm using this in my code isn't as simple as my example code...but I think it gets the idea across.)  Am I missing something concerning OO design that makes what I'm trying to do an OOP anti-pattern? Surely the compiler should be able to determine which method I'm trying to use as long as I specifically tell it which one I want.  Given MyClass myClass = new MyClass(); I would expect the following code to work:  double d = myClass.MyMethod(); string s = myClass.MyMethod();   I would expect the following code to have problems:  var v = myClass.MyMethod();   But even in the case of var it should result in a compile error.  Can anyone see what I'm doing wrong here? I'm more than happy to be corrected. :-)


I need to upload the audios and videos on server in a specific folder via FTP and then let the content managers to select them when they want to upload any of them in add/content path (because it takes a long time to upload them via the Add Content user interface). Is there such a capability in Drupal 7?

How do you set an existing file path for a file field, in Drupal 7? The only option I see is to upload the file again.  In Drupal 6,  seems to do this.   Does  or  along with file field allow assignment of server files? Is there an API to programmatically manage file fields?  Edit I just discovered that this can all be done with the media module. I also have  installed. However it is not completely intuitive, so here are the steps I took:  Import to media library: /admin/content/media/import    Create a mediafile asset field. This allows you to attach from the library.    Display formats (example for audio) are at /admin/config/media/types/manage/audio/display/, instead of content type "manage display" which only provides "large", "small", "preview", etc.


How can I access cookies my browser stored? I am using Chrome.    This is the cookies panel in the Settings->Privacy->Content Settings->All cookies and site data. Is there a way to access these files manually and edit them?

I wish to view, add and edit the cookies of my google chrome. Can anyone suggest to me a way to do it?


I completely forgot I soaked the rice on Monday night. It was completely submerged in water. Left at room temperature. If I cook it now, would it be safe to eat?

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


It is handle after I configuring taskOuput's launchPath to "/usr/bin/sudo". How can I modify the code to make it works?  let theTask = Process() let stdin = FileHandle(forReadingAtPath:"c") let taskOutput = Pipe() theTask.launchPath = "/usr/bin/sudo" theTask.standardOutput = taskOutput theTask.standardInput = stdin theTask.standardError = taskOutput theTask.arguments = ["mkdir", "/usr/local/newfolder"] theTask.launch() theTask.waitUntilExit()

I'm writing a C Shell program that will be doing su or sudo or ssh. They all want their passwords in console input (the TTY) rather than stdin or the command line.  Does anybody know a solution?  Setting up password-less sudo is not an option.   could be an option, but it's not present on my stripped-down system.


I need to replace Blender 2.80, which I am unable to uninstall with Blender 2.82a.

I installed Blender for a project working on and it's way more than I need. I'd like to uninstall it, but can't figure out how to do so. It's not showing up in Programs (using Windows 9) and I can't find instructions on how to remove it in the Blender documentation. Any assistance would be greatly appreciated. Thanks.


When I put ice cubes in a glass of water, I find that sometimes they will stick together and form a sort of "bridge" between them as they melt.  There is usually a visible line where one ends and the other begins, and they break apart if pushed (but for the most part they stick together if they aren't interfered with).  I'm wondering how they form this bridge in the first place if they're melting, and why it stays together.

I was drinking iced-water from a drinking glass (made of glass) at a restaurant yesterday when I was taking a drink, I noticed that there is very little ice water coming out and then suddenly, the ice water mixture comes crashing down. With my open mouth overfilled with ice water, my shirt gets wet – I hate when this happens. After drying myself off, I started thinking why this does happen:   How does ice that starts off loose and separated in water fuse together to form one large clump? What causes the ice-water mixture to stop flowing momentarily and then suddenly starting flowing again? Is it that the ice fuses together in the glass and forms one large clump, and then the friction with the edges builds a "dam-like" situation? Or are there individual pieces of ice fusing with the edges of the drinking glass damming-up the ice?


If a zombie or skeleton that you have animated with  is reduced to 0 hit points, can you reanimate it using Animate dead?  The spell description only says:     Choose a pile of bones or a corpse of a Medium or Small humanoid within range.   Well presumably when a skeleton reduces to 0 hit points it becomes a pile of bones. Even if the bones are damaged, the spell does not require 'unbroken bones'.  As a dungeon master I might require using the  cantrip to restore broken bones to some degree, however I can't find any specific ruling.  I'm looking for a rules focused answer rather than a fluffy home rule answer :)

I’ve recently been doing some builds for Necromancers for a one-shot we’ll be doing. I have been struggling to find anything that mentions how to keep up with all of the corpses you will need for the Animate Dead and Create Undead spells.  There seems to be an indefinite period a corpse can stay a corpse within the 5E RAW.  I also haven’t found anything stating that undead that are killed again cannot be animated again, within RAW.   Once my zombie or skeleton dies and becomes a corpse again, may I reuse the now corpse according to RAW?


NOT the William P. McGivern/David W. O'Brien story. This short story had Brown colonized with helpful microbes (from the days before nanites) that did him all sorts of good, however sometimes they decided what his good would be, independent of his 'druthers—-so they would keep him from drinking alcohol or induce him to be aroused by a woman that the microbes themselves wanted to colonize. Probably from the late '60s through the '70s. Thanks.

Don't remember the exact start to the story, but it went something like "walking along a path" or something, and when he hears what sounds like a shotgun blast behind him, he then feels something strike him in the butt. He passes out, and when he awakens, he discovers that the "shotgun blast" was actually a miniature spaceship that exploded and shot miniature aliens into his body. The aliens prove to be very beneficial because they clean up all the toxins and other poisons in his body. They can be transmitted through kissing or sexual activity.  Any help with the name of the story would be greatly appreciated.  Dan


I am doing simple jsp servlet program to check whether the logged user is valid or not?  If I am running db program seperately, then it is working fine that means connection and other things are correct.  But if I am integrating it with JSP & Servlet with valid inputs then it is throwing java.lang.NullPointerException.  Connection.java  public class ConnectionClass {     public static Connection con=null;      public static Connection getOracleConnection() {         try {              Class.forName("oracle.jdbc.driver.OracleDriver");            con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe",Constants.OracleUsername,Constants.OraclePassword);           } catch(Exception e) {            System.out.println("Error to create the connection ");         }          return con;     } }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


As far as I understand, Signoid function is used for mapping the outputs of neural network to the values between 0 and 1. Why is using rectified linear unit(ReLU) as activation function in deep neural networks, works faster? Can you please explain the mathematical concept behind it?

I found rectified linear unit (ReLU) praised at several places as a solution to the  for neural networks. That is, one uses max(0,x) as activation function. When the activation is positive, it is obvious that this is better than, say, the sigmoid activation function, since its derivation is always 1 instead of an arbitrarily small value for large x. On the other hand, the derivation is exactly 0 when x is smaller than 0. In the worst case, when a unit is never activated, the weights for this unit would also never change anymore, and the unit would be forever useless - which seems much worse than even vanishingly small gradients. How do learning algorithms deal with that problem when they use ReLU?


When deleting a file or a folder, I don't get a prompt requesting confirmation of the deletion (the way I'm used to with Windows).

I'm sick of accidentally deleting files and directories as DEL button is badly located on my keyboard. I would really like it if ubuntu asked me to confirm before deleting anything. Is there a way to do this?


Let $X$ be the set of all continuous and real-valued functions on $\mathbb{R}$. X is a commutative ring with pointwise addition and multiplication.   Let $\alpha \in \mathbb{R}$ be arbitrary.      (1) Show that $I = \left\{f \in X \ \big\vert \  f(\alpha) = 0\right\}$ is a maximal ideal of $X$.      (2) Show that $X/I$ is isomorphic to $\mathbb{R}$   (1)  I tried to visualize this task. The only reason $I \neq X$ is position $\alpha$, where I cannot create another value than 0 using translation or rotation. If I take any function $f'$ for which $f'(\alpha) \neq 0$ applies, I can use the fact that $X$ contains all functions except for the ones being not 0 at $\alpha$, and can therefore create any continuous, real-valued function on $\mathbb{R}$.   While this seems clear visualized at the paper, I have no clue how to formally write this down, can you please help me to formalize it? I'm especially stuck because I don't know how to formally write down all continuous, real-valued functions on $\mathbb{R}$.  (2)   I need to find a bijection between $X/I$ and $\mathbb{R}$, but don't understand why this is possible. As far as I understand $X/I$ are all continuous real-valued functions on $\mathbb{R}$ that are not $0$ at position $\alpha$. But I can find more than one of those functions for each $r \in \mathbb{R}$ which is in $X/I$. So how could I find a bijection? Where is my mistake?

Well, the problem I'm trying to solve is this:      Let $A$ be the ring of all continuous functions from $\mathbb{R} \to \mathbb{R}$. Show that $M = \{f \in A: f(0)=0\}$ is a maximal ideal of $A$.   I tried to show that if $J$ is an ideal of A that properly contains M, so $J = A$: we know that there is a function $g \in J$ with $g(0) \neq 0$. So, we have that $$J \supseteq \langle g, M\rangle=\{ag+f;a \in A, f\in M\}$$   I tried to show that 1 $\in$ $\langle g,M\rangle$. However I'd have to find some function $h(x)\in A$ such that $h(x)(ag+f) = 1$, but this function $h$ has to be different from 0 for all x $\in \mathbb{R}$, so I don't know how to find this function.  My second idea to solve this problem was prove that the quocient $A/M$ is a field. We have that $$A/M = \{h(x) + M; h(x) \in A\},$$ but again I have the problem to show that all elements of $A/M$ are units.  If someone could help, I would be really grateful (:


Today this "forbidden" ethernet/airplane mode icon appeared in the Panel.    The little square one with the red circle. How do I remove it please? I've tried Alt+right-click, but the only option not grayed out is Always on top which isn't much help.

The following is a systray applet icon that appeared in my Unity session after I upgraded to Ubuntu 16.10. Its menu is tall, narrow and empty. What is it?


I found a big object file from .git/objects/ , I am wondering that what the file is(when added, from which file in working directory).  I tried cat-file but it shows only contents, not file names.  Is there a git command find file name(path) from object hash, It is like:  % git find-path? <object-hash> -> List of filename(path) of this object

Given the hash of a blob, is there a way to get a list of commits that have this blob in their tree?


N cannot be partitioned into a finite number of arithmetic progression with distinct steps except the trivial case $\{1,2,...\}$  The hint told me to consider: $$\sum_{n\in N}z^n=\sum_{i=1}^r\frac{z^{a_i}}{1-z^{d_i}}$$ and I figured out for some $j$ we have  $a_j=1$, but I don't know how to prove $d_j=1,r=1$

An arithmetic sequence of step $d$ is a set of the form: {$a, a+d, a+2d, a+3d, ...$} where $a, d$ are positive integers.    Show that the positive integers cannot be partitioned into a finite number of arithmetic sequences s.t. each sequence has a distinct step $d$. (Except the trivial sequence $a=1, d=1$.)  Now the book gives me a hint: Write $\sum_{n\in\mathbb{N}}z^n$ as a sum of terms of the type $\frac{z^a}{1-z^d}$.    But it isn't clear that the power series can even be put such a form, and even if it can, why does that help me?


Hello I am solving an integral with a natural logarithm that has a parameter. Let say $I(a)=\int_0^\pi\ln(1-2a\cos(x)+a^2)dx$ Then for differentiation under integral sign and that yields $I'(a)= \int_0^\pi\frac{2a-2\cos(x)dx}{ 1-2a\cos(x)+a^2}$.  I chose take $aI'(a)$ and then I have That $I(a)= \pi\ln(a^2)+a\pi$  My questions:    is there any wrong over result? where I shoud to take considerations about $a$? magnitude. what is the integral problem about this exercise?   Thanks, any help, any correction.

For $a\ge 0$ let's define $$I(a)=\int_{0}^{\pi}\ln\left(1-2a\cos x+a^2\right)dx.$$ Find explicit formula for $I(a)$.   My attempt: Let  $$\begin{align*} f_n(x) &= \frac{\ln\left(1-2 \left(a+\frac{1}{n}\right)\cos x+\left(a+\frac{1}{n}\right)^2\right)-\ln\left(1-2a\cos x+a^2\right)}{\frac{1}{n}}\\ &=\frac{\ln\left(\displaystyle\frac{1-2 \left(a+\frac{1}{n}\right)\cos x+\left(a+\frac{1}{n}\right)^2}{1-2a\cos x+a^2}\right)}{\frac{1}{n}}\\ &=\frac{\ln\left(1+\dfrac{1}{n}\left(\displaystyle\frac{2a-2\cos x+\frac{1}{n}}{1-2a\cos x+a^2}\right)\right)}{\frac{1}{n}}. \end{align*}$$ Now it is easy to see that $f_n(x) \to \frac{2a-2\cos x}{1-2a\cos x+a^2}$ as $n \to \infty$. $|f_n(x)|\le \frac{2a+2}{(1-a)^2}$ RHS is integrable so $\lim_{n\to\infty}\int_0^\pi f_n(x)dx = \int_0^\pi \frac{2a-2\cos x}{1-2a\cos x+a^2} dx=I'(a)$. But  $$\int_0^\pi \frac{2a-2\cos x}{1-2a\cos x+a^2}=\int_0^\pi\left(1-\frac{(1-a)^2}{1-2a\cos x+a^2}\right)dx.$$ Consider $$\int_0^\pi\frac{dx}{1-2a\cos x+a^2}=\int_0^\infty\frac{\frac{dy}{1+t^2}}{1-2a\frac{1-t^2}{1+t^2}+a^2}=\int_0^\infty\frac{dt}{1+t^2-2a(1-t^2)+a^2(1+t^2)}=\int_0^\infty\frac{dt}{(1-a)^2+\left((1+a)t\right)^2}\stackrel{(*)}{=}\frac{1}{(1-a)^2}\int_0^\infty\frac{dt}{1+\left(\frac{1+a}{1-a}t\right)^2}=\frac{1}{(1-a)(1+a)}\int_0^\infty\frac{du}{1+u^2}=\frac{1}{(1-a)(1+a)}\frac{\pi}{2}.$$ So $$I'(a)=\frac{\pi}{2}\left(2-\frac{1-a}{1+a}\right)\Rightarrow I(a)=\frac{\pi}{2}\left(3a-2\ln\left(a+1\right)\right).$$  It looks too easy, is there any crucial lack?  $(*)$ — we have to check $a=1$ here by hand and actually consider $[0,1), (1,\infty)$ but result on these two intervals may differ only by constant - it may be important but in my opinion not crucial for this proof.


For a map my friend was making, I was trying to make grenades but they failed. I need a data tag that can make it so that as soon as it touches the ground it explodes.

I am trying to make a snowball that triggers a command when it hits a player in 1.15, but I don't know how to do that. When I do execute at @e[type=snowball] run gamemode spectator @a[distance=..2] it only runs the command if it goes right next to them.


I am preparing response to comments given by the reviewers for my thesis. I wrote each of their comment as a question using exam document class. For giving response to their comments I am using answer option. So the format is somewhat like this:   \documentclass[answers]{exam} \begin{document} \section{First Reviewer Comments}     \begin{questions}     \question First comment.     \begin{solution}     My response.     \end{solution}     \end{questions} \end{document}   It prints [Solution: My response] inside a box. I want to replace "Solution" by "Response". How to do this ?

In exam class, how to print Answer instead of Solution when using  \begin{solution}  \end{solution}   in question-answer format?


On Linux Mint Rebecca, my current LC_TIME setting is LC_TIME="en_US.UTF-8"  I would like to execute date and watch how the current date is displayed in a Chinese format with Chinese characters.  Therefore, I thought I have to set the LC_TIME variable this way:  LC_TIME=zh_CN.UTF-8   however, when I execute date I still get the date in the English style format, moreover when I execute locale I see the LC_TIME variable did not change its value at all.   Output of locale -a:  C C.UTF-8 de_DE.utf8 en_AG en_AG.utf8 en_AU.utf8 en_BW.utf8 en_CA.utf8 en_DK.utf8 en_GB.utf8 en_HK.utf8 en_IE.utf8 en_IN en_IN.utf8 en_NG en_NG.utf8 en_NZ.utf8 en_PH.utf8 en_SG.utf8 en_US.utf8 en_ZA.utf8 en_ZM en_ZM.utf8 en_ZW.utf8 POSIX

I used to be able to copy&paste (or type if I load respective keyboard layout) any kind of characters (eg. é ö ñ ß و 好) in my console/terminal.  Now I bought a new computer and it does not work any more, only English/ASCII characters (but in other programs, e.g. firefox, it still works).  Distribution: Ubuntu. Terminals tried: gnome-terminal, xterm, konsole.  I tried  but after reboot echo $LANG still gives C. I also tried setting Character encoding to Unicode(UTF-8) in the gnome-terminal Terminal-menu - without effect.  Question: How can I get a terminal that is able to deal with non-English characters?


I try to add and get data using sharedPreferences, but I only receive this error in logcat:  Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference   The line of code:  public static final String PREFS_NAME = "MyPrefsFile"; SharedPreferences prefs = getSharedPreferences(PREFS_NAME, 0); // <-error here   I need create first the xml file?

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Consider a closed curve of finite length.     There is at least one straight line that can bisect both the perimeter and the area of the curve.   Why is this statment true?

Let $S$ be a simple closed curve in ${\Bbb R}^2$ enclosing a convex region $I$.  Must there exist a straight line which cuts $S$ into two pieces of equal length and also cuts $I$ into two regions of equal area?  If so, how can such a line be found?  [If the answer is, "no, because the sandwich might have a pathological boundary", then please also consider the case of non-pathological sandwiches.]


I want to generate random number in a specific range. (Ex. Range Between 65 to 80)  I try as per below code, but it is not very use full. It also returns the value greater then max. value(greater then 80).   Random r = new Random(); int i1 = (r.nextInt(80) + 65);   How can I generate random number in between range?

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


I wrote the code with extracts words from corpus, then tokenizes them and compares to sentences. The output is Bag of Words (if word is in the sentence 1, if not 0).   import nltk import numpy as np from nltk import FreqDist from nltk.corpus import brown   news = brown.words(categories='news')  news_sents = brown.sents(categories='news')   fdist = FreqDist(w.lower() for w in news)  vocabulary = [word for word, _ in fdist.most_common(100)]  num_sents = len(news_sents)   for i in range(num_sents):     features = {}     for word in vocabulary:          features[word] = int(word in news_sents[i])       bow = "".join(str(n) for n in list(features.values()))     f = open("D:\\test\\Vector.txt", "a")      print(bow, file=f)      f.close()   In this case output string is 100 characters long. I want to split it into chunks of some arbitrary length and assign chunk number to it. For example:  print(i+1, chunk_id, bow, sep="\t", end="\n", file=f)   Where i+1 will be sentence id. To visualize what I mean, lets take strings of length 12 >> "110010101111" and "011011000011". It should look like:  1 1 1100 1 2 0101 1 3 1111 2 1 0110 2 2 1100 2 3 0011

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


I am trying to implement PCA (NIPALS method) using Excel. The problem is that my results are not exactly matching with the results of R. There is only a difference in sign: if my scores are positive, then scores using R are negative.   I don't know what is going on. What to do?

I performed principal component analysis (PCA) with R using two different functions (prcomp and princomp) and observed that the PCA scores differed in sign. How can it be?  Consider this:  set.seed(999) prcomp(data.frame(1:10,rnorm(10)))$x              PC1        PC2  [1,] -4.508620 -0.2567655  [2,] -3.373772 -1.1369417  [3,] -2.679669  1.0903445  [4,] -1.615837  0.7108631  [5,] -0.548879  0.3093389  [6,]  0.481756  0.1639112  [7,]  1.656178 -0.9952875  [8,]  2.560345 -0.2490548  [9,]  3.508442  0.1874520 [10,]  4.520055  0.1761397  set.seed(999) princomp(data.frame(1:10,rnorm(10)))$scores          Comp.1     Comp.2  [1,]  4.508620  0.2567655  [2,]  3.373772  1.1369417  [3,]  2.679669 -1.0903445  [4,]  1.615837 -0.7108631  [5,]  0.548879 -0.3093389  [6,] -0.481756 -0.1639112  [7,] -1.656178  0.9952875  [8,] -2.560345  0.2490548  [9,] -3.508442 -0.1874520 [10,] -4.520055 -0.1761397   Why do the signs (+/-) differ for the two analyses? If I was then using principal components PC1 and PC2 as predictors in a regression, i.e. lm(y ~ PC1 + PC2), this would completely change my understanding of the effect of the two variables on y depending on which method I used! How could I then say that PC1 has e.g. a positive effect on y and PC2 has e.g. a negative effect on y?    In addition: If the sign of PCA components is meaningless, is this true for factor analysis (FA) as well? Is it acceptable to flip (reverse) the sign of individual PCA/FA component scores (or of loadings, as a column of loading matrix)?


I have a .ipa file which I want to install into iPhone simulator. I am trying this in a MAC m/c running OS X 10.7 version. Please help me on how to install the .ipa into iPhone simulator.  Thanks, Sitam

I have an iphone simulator running on my Mac.   I have a .ipa file, can you please tell me how can I install it on the simulator?


I have a task with a few different questions 'if a given set is a vector space'. I have chosen one to show my way of solving such examples and ask you if it is a correct way. So  We can simply say that these conditions   $(p+q)v = pv + qv$ $p(u+v) = pu + pv$ and so on...   (where u,v belong to $\Bbb Q_n[x]$ and $p,q$ belong to $\Bbb Q$)  Are gonna be fulfilled as we operate on 'normal/common' rational numbers And now I check if Q x Qn[x] gives us a rational number as a result yes? If so I can easily state that operations in which we use only rational numbers give us a rational result.  If my way of thinking is wrong please correct me and if you are able to do that let help me find the correct way of solving tasks like this one. Thanks.

Can someone please explain how polynomials are vector spaces? I don't understand this at all. Vectors are straight, so how could a polynomial be a vector. Is it just that the coefficients are vector spaces? I'm really not understanding how polynomials tie in to linear algebra at all? I can do all the problems with them, because they are done the same way as any other vector problem, but I can't understand intuitively what I'm doing at all.


I want to split the string first by the commas and then by the space. I have written the code but it is not working  public class HelloWorld{   public static void main(String []args){        String [] y={};        String [] l=null;        int k=0;    String val = "10.0.0.0 255.255.255.0 net-0-rtr.example.com 2,10.0.1.0                   255.255.255.0 net-1-rtr.example.com 1";    String [] x = val.split(",");   for(int i=0;i<x.length;i++){         y = x[i].split(" ");         int b=0;        for( ;k<y.length;){          l[k]=y[b];          k++;          b++;     }    k=b;}  }}   It is giving the following output:- Exception in thread "main" java.lang.NullPointerException     at HelloWorld.main(HelloWorld.java:16)


I am using Xubuntu 16.04 LTS.  When I run sudo apt-get dist-upgrade in the Terminal there isn't any problem.    After that, I want to copy the .deb file in /var/cache/apt/archives/ using Thunar file manager, but it doesn't exist.   See screenshot below:    But the locate command finds it:    The summary, file .deb is there in /var/cache/apt/archives/  I am confused, what’s wrong with my system? Could you help about this problem, please?

I know that packages installed with apt-get are stored in /var/cache/apt/archives.  I just installed mariadb server in Ubuntu 16.04 with following command:  sudo apt install mariadb-server   When I tried to find packages in /var/cache/apt/archives, there are no packages. Where are they stored if it's not in this directory?


Obviously, the magnitude of the orthogonal matrix is 1, which is easy to prove.. However, I wonder how can one prove that the eigenvalue of an orthogonal matrix is $-1$, if the determinant of this matrix is $-1$?  Thanks a lot.  Thanks for the help that I can prove it now from the conjugate pairs point of view.  Is there a method by proving that $\det(I+A)=0$?

I want to show that if a real orthogonal matrix $A$ has determinant $-1$ then $\lambda=-1$ must be an eigenvalue of $A$.  I have proven this in a long-winded way and I was wondering if these is a quick way of seeing it.


BeanUtils.copyProperties() throw NullPointerException on Tomcat, but on localhost it works fine.  I've checked everything and dto isn't null, only the properties of user is null which is fine.  public void saveUser(UserDTO dto) {     User user = new User();     BeanUtils.copyProperties(dto, user);      session.beginTransaction();     session.save(user);     session.getTransaction().commit(); }   my User.java  public class User {      @Id @GeneratedValue     private long id;      private String userId;     private String firstName;     private String lastName;     private String email;     @Enumerated(EnumType.STRING)     private Role role;     private String encryptedPassword;     private String salt;     private String token;  ... getters and setters method ... }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


In Deathly Hallows, why couldn’t Harry drink the polyjuice and turn into any Muggle?  Surely it would have been much easier than seven people turning into Harry Potter.

In the Battle of the Seven Potters (Chapter 'Seven Potters' in "Harry Potter and the Deathly Hallows"), 6 people (Ron/Fred/George/Hermione/Fleur/Mundungus) take the Polyjuice Potion to act as decoys for Harry.   Wouldn't it have made more sense for Harry to have taken the Polyjuice Potion to turn to some low-profile character instead, to escape the Dursleys' residence?


I am trying to restore a database with the following command:  $ sudo -u postgres pg_restore -C -d dvdrental dvdrental.tar  [sudo] password for t:    However, I am receiving the following error message:      could not change directory to "/home/t/mydata/.../relation model/SQL/implementations/Implementations, i.e. relational database management systems/postgreSQL/general/web/postgresqltutorial/databases": Permission denied      pg_restore: [archiver] could not open input file "dvdrental.tar": No such file or directory   I was wondering why I can't change directory to the current directory with permission denied?  File permission bits are:   -rw-rw-r-- 1 t t 2838016 May 26  2013 dvdrental.tar   Is it because one of its ancestry directory is not both readable and executable by any one?  The file has  many ancestry directories, and how can I verify that?


Thought experiment:   Entangle a pair of particles.  Package one half of each pair in a special package, and send it out in a nano-spaceship keep the other half of the pair of entangled particles here on earth accelerate nano-spaceship to 99.99999999999999% of the speed of light using a number of    Due to Lorentz ,  $$ L = L _\text{0} \sqrt {1 - \frac {v^{2}}{c^{2}}} $$  In one years time, the spaceship would have traveled 93B ly away from us.  After one year of travel, the spaceship could be preconfigured to detect the CMB in the direction of travel, and then trigger their quantum entangled particle to send a '0' or a '1' depending on whether the CMB was detected.  Repeat this process using any number of spaceships in any number of directions, and soon you would experimentally show how big the universe really is.  Any problems?

Thought experiment:   Entangle a pair of particles.  Package one half of each pair in a special package, and send it out in a nano-spaceship keep the other half of the pair of entangled particles here on earth accelerate nano-spaceship to 99.99999999999999% of the speed of light using a number of    Due to Lorentz ,  $$ L = L _\text{0} \sqrt {1 - \frac {v^{2}}{c^{2}}} $$  In one years time, the spaceship would have traveled 93B ly away from us (in the spaceships relative frame)  After one year of travel, the spaceship could be preconfigured to detect the CMB in the direction of travel, and then trigger their quantum entangled particle to send a '0' or a '1' depending on whether the CMB was detected.  Repeat this process using any number of spaceships in any number of directions, and soon you would experimentally show how big the universe really is.  Any problems?


Inspired by the  and , apart from SU(N), now I am particularly looking into the exact sequences of SO(N), but I will like to loosen the conditions of the previous ,     Q1. $$1 \to A \to SO(N) \to B \to 1$$   where any of $A$,$B$ can contain finite group or discrete groups.  I am further interested in just three cases SO(8), SO(9), SO(10),  -     Q2. $$1 \to A \to SO(n) \to B \to 1$$    I wonder whether, when there is any example such that $A$    $$A=U(1) \times SU(2) \times SU(3)\;\;\; \text{or} \;\;\;A \supseteq U(1) \times SU(2) \times SU(3)?$$   (there can be an additional discrete finite group parts for $A$ such as additional $\mathbb{Z_N}$)   or whether there is any example such that $B$    $$B=U(1) \times SU(2) \times SU(3)\;\;\; \text{or} \;\;\;B \supseteq U(1) \times SU(2) \times SU(3)?$$   (there can be an additional discrete finite group parts for $B$ such as additional $\mathbb{Z_N}$)

Inspired by the , I am particularly looking into the exact sequences of SU(N), but I will like to loosen the conditions of the previous ,     Q1. $$1 \to A \to SU(N) \to B \to 1$$   where any of $A$,$B$ can contain finite group or discrete groups.    I am particularly interested in SU(5),     Q2. $$1 \to A \to SU(5) \to B \to 1$$    I wonder whether there is any example such that both $A$ and $B$ contains the same number of generators of continuous part of Lie groups (there can be an additional discrete finite group parts such as additional $\mathbb{Z_N}$)? (for example $SU(5)$ has 24 generators. Is there any example such that $A$ and $B$ have 12 generators for continuous part of Lie groups for each $A$, $B$.) How about  $$A=U(1) \times SU(2) \times SU(3)\;\;\; \text{or} \;\;\;A \supset U(1) \times SU(2) \times SU(3)?$$  Or whether there is any example such that $B$  $$B=U(1) \times SU(2) \times SU(3)\;\;\; \text{or} \;\;\;B \supseteq U(1) \times SU(2) \times SU(3)?$$ (there can be an additional discrete finite group parts for $B$ such as additional $\mathbb{Z_N}$.)


Do we use "to" or "in" when talking about being to/in another location?

In the following two examples, what is the difference between the usage of been to and been in? They seem like they have the same meaning but I’m not sure.     -Have you ever been to Florida?   -Yes, I’ve been to Florida many times.              -Have you ever been in Florida?   -Yes, I’ve been in Florida many times.


I want to write a csv with the opencsv libary, however, when running the code I get a NullPointerException.  public void exportToCSV(ArrayList<Data> list) throws IOException {         log.info("write CSV file");          String writerPath = "C:\\Users\\User\\Desktop\\Output\\output.csv";          CSVWriter writer = new CSVWriter(new FileWriter(writerPath), ';');          //headers                 String [] entries = {"ID", "Date"};          writer.writeNext(entries);          List<String[]> data = new ArrayList<String[]>();         for (int m = 0; m < list.size(); m++) {             data.add(new String[] {                     list.get(m).getID,                     (list.get(m).getDate().toString()==null) ? "null" : list.get(m).getDate().toString(), //Here i get the NullPointerException             });         }         writer.writeAll(data);         writer.close();     }   I guess that getDate() is null, which type is a Timestamp. However, why does my proposed solution not work in writing a String when getDate() is null.  I apprecaite your reply!


The Ring of Spell Turning lets the target turn the spell back on the caster:     ...using the slot level, spell save DC, attack bonus, and spell casting ability of the caster.   The description is silent on who concentrates.  So if Hold Person was turned back on the caster, could the caster prevent the downsides of this by ceasing concentration? Or is concentration assumed by someone else?

A cleric casts a Command spell targeting you, specifying the Flee option.  You have a Ring of Spell Turning and you get a 20 for the save, so the spell is returned.  We are going to assume that the cleric fails his save.   The spell is returned but, can you specify other option for the spell (halt, approach, etc.) ? From where the cleric will flee?  From his original position, from you, from the ring, from himself? In case the spell was cast using a higher level (affecting a second creature), could be the spell be returned? Extra: In case the returned spell had concentration or a dismiss option. Could the original caster finish the spell ending the concentration or using the appropriate action to end the effect?  When could he finish the concentration?


I read this a long time ago, perhaps 30 years, and the story may have been older than that, in Danish. I remember some fragments that are really quite bizarre, but the main gist was that the general population lived in a sort of kindergarten, where everything was kept non-scary. Some points I remember:   Everybody was known by their first name only. When people got too old, they were given a party and euthanised. This was called something euphemistic, like 'retiring' or 'being let go' or similar. Once, an air-plane passed over the community and made a loud noise - and it was later announced that the pilot had been 'let go' as a consequence.   There is of course a young, male hero, who runs away, but this is where I think I may be mixing up two stories, because I seem to remember there was something about all the worries and trauma of reality being kept away from most people, but then channeled into a few individuals, somehow.

Things I remember about this book:   Every child was selected for a certain job/career; If twins were born, one was always killed; Seeing colors for the first time (describing the color of an apple); Seeing war and death and poverty.   Does anyone have any idea what this book might be?


$$\sum_{n=1}^{\infty} \left(\dfrac{n}{n+1}\right)^n$$  to show that this diverges should I use the $n^{th}$ term test?   So far I have substituted infinity for $n$. Could I use L'hopital's rule to then show that this series diverges?

I have managed to use the root test and get as far as getting the limit to equal to $1$. But, I still need clarification on why the answer for the limit to this questions is $\alpha < 1$. \begin{align} \sum _{n=0}^{\infty }\left( \frac {\alpha n} {n+1}\right) ^{n}\end{align} \begin{align} \lim _{n\rightarrow \infty }\left( \left( \frac {\alpha n} {n+1}\right) ^{n}\right) ^{1/n} =\left| \frac {\alpha n} {n+1}\right| =\alpha \lim _{n\rightarrow \infty }\left| \frac {n} {n+1}\right|=1.\end{align}


As I was going over my lecture notes I found the following problem which we haven't proof in class In the example we know $H$ is a Hausdorff topological space and $C$ is a compact topological space and we need to find a homomorphism between them. And my lecture notes say it suffices to find a continuous bijection $f$ from $C$ to $H.$ So I guess the following proposition which we haven't proof must hold If $H,C$ and $f$ as above then $g=f^{-1}$ is continuous. How can I prove this? Thank, You

A continuous map from a compact space to a Hausdorff space is closed. Why this is true?  Help me please I want to learn why this is correct.


I was stuck with a very strange issue. Can anyone suggest me what to do, the scenario is: I want to allow my site user to create record and along with that the user can upload the file(can be greater than 2 gb). File should be associated with that particular record in salesforce. Can anyone help me out in this scenario?

How to upload a file of size 2GB from Apex? Is there any sobject that I can make use of?


When discussing the interference pattern of a double slit, it is often described as two sets of concentric circles rippling out towards the wall and interfering with each other. In truth, each circle beyond the initial two propagating towards the wall represents a FOLLOWING wave (or particle)--one that happens slightly later in time than the wave crest before it. So how can these following waves interfere with the first wave if the photon is shot one at a time?  I must be understanding these diagrams wrong, but I don't understand how...    Here's another way of looking at the question:

In a double-slit experiment, interference patterns are shown when light passes through the slits and illuminate the screen. So the question is, if one shoots a single photon, does the screen show interference pattern? Or does the screen show only one location that the single photon particle is at?


In how many ways 2n people can be arranged in n rooms with exactly 2 people in each room  for example: arranging 4 people (1,2,3,4) in 2 rooms with above condition 1 is  (1,2) (3,4)  (1,3) (2,4)  (1,4) (2,3)  Thus 3 possible ways

There are $2n$ players in a chess tournament. The first round consists of pairing the players to participate in $n$ matches with every player playing one match. In terms of $n,$ how many ways can this pairing take place?  The first pair of people can be chosen from $\binom{2n}{2}.$  Since we chose the first pair, the next pair will be chosen from an amount of $\binom{2n-2}{2}.$   This pattern continues till $\binom{2}{2}$ which is for the $n$th pair.  Hence, the pairings will be $$\binom{2n}{2}\cdot\binom{2n-2}{2}\cdot...\cdot\binom{2}{2}.$$  Dividing by $n!$ gets the ways $2n$ people can be chosen to play $n$ games.  How do I simplify this?


Consider the following sentence     There are many different fruits (some are harmful: apple,   mango, etc.).   How do you deal with etc.).? It doesn't look nice at all.

Example:     It's all about apples, oranges, bananas, etc.   VS.     It's all about apples, oranges, bananas, etc..   Update  What happens if the abbreviation is inside parentheses, do you place a dot after and before the closing parenthesis?     It's all about fruit (apples, bananas, etc.).


(nautilus:6104): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed  (nautilus:6104): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed Could not register the application: Timeout was reached  (nautilus:6104): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed  (nautilus:6104): GLib-GObject-WARNING **: invalid (NULL) pointer instance  (nautilus:6104): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

When I type nautilus I have these lines:   (nautilus:28316): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed     (nautilus:28316): GLib-GIO-CRITICAL **: g_dbus_interface_skeleton_unexport: assertion 'interface_->priv->connections != NULL' failed Impossible d'enregistrer l'application: Le délai d'attente est dépassé    (nautilus:28316): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed     (nautilus:28316): GLib-GObject-WARNING **: invalid (NULL) pointer instance     (nautilus:28316): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed   I tried to reinstall Nautilus, but that did not fix the problem. Does somebody have any ideas as to how to fix the problem?


It seems to be that when I install an application via command line (with sudo apt-get someapp), that the application does not appear in the Ubuntu Software list. Is it possible to get such applications to appear there?    Running the command in the comments, it updates and I see this:    ...   All packages are up to date.   W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used.    GPG error: http://dl.google.com/linux/chrome/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13   W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used.    GPG error: http://dl.google.com/linux/earth/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13   W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13   W: Failed to fetch http://dl.google.com/linux/earth/deb/dists/stable/Release.gpg  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13   W: Some index files failed to download. They have been ignored, or old ones used instead.   Reading package lists... Done   Building dependency tree          Reading state information... Done Package software-center 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 'software-center' has no installation candidate     All packages are up to date. N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://dl.google.com/linux/earth/deb stable InRelease' doesn't support architecture 'i386' Reading package lists... Done Building dependency tree        Reading state information... Done Package software-center 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 'software-center' has no installation candidate

I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal?


I am trying to install OS X on VirtualBox VM on Windows 7, but it is giving me a message that "hardware acceleration" is missing on my PC.  How can I deal with this problem? …and is this suitable for iOS app development using Xcode?

I have finally successfully managed to install Mac OS X in a virtual machine on my Windows 7 laptop using VirtualBox and a tutorial from Lifehacker.  Performance is very slow, with Mountain Lion reporting that it is seeing just 4MB video memory (I didn't manage to load the Intel HD3000 driver). Youtube is essentially unplayable, with even the audio potion stuttering. That said, the interface and general UI is pretty acceptable.  Even with such slow performance, does it make sense to download and develop with Xcode? I am allocating 3GB of RAM. What would performance be like under those conditions?


(e.g. ) should have an ability to bookmark (star / favorite). If it’s available for reading, user should be able to bookmark it.  Similar question was raised in  “Can a historically locked question still be starred, or is that behavior frozen too?”   Also as we have reopen link for closed questions, should be similar link to vote for unlocking the Historical Locked question?

Historical locks are sometimes applied to questions.   What is a historical lock? What is the purpose of a historical lock? How are questions affected by historical locking? When is it appropriate to lock a question for historical reasons?  When is it not appropriate? How do I request a historical lock for a question? What should I do if I notice a serious problem with a historically-locked question or one of its answers?


I've heard from mathematicians, and not mathematicians, that the infinity is not a number. Is a concept, an idea.   Good! But we are in the world of mathematics, a world in where it's supposed to be able to define any mathematical object (I have doubts about this...) with precision and rigour.  I've been dealing with this concept in many areas but, SINCE THEN, I don't have the precise meaning. I don't like the idea of talking without definitions in math...  So I was wondering if the math definition of this concept exists? And where I can find it?

On , I was bored and asked for  and the result was (indeterminate). Another two that give the same result are  and .  From what I know, given $x$ being any number, excluding $0$, $\frac{x}{x} = 1$ is true.  So just what, exactly, is $\infty$?


So I recently had a shortage on EVERYTHING, and my vault became unhappy. Although they are all healed and I have full resource bars again, my dwellers that were originally at 90-100% happiness are now at 10%, any tips on how to fix this??

I am playing Fallout Shelter, and I do not know how to make everyone happy. I have tried getting a lot of Food, Energy, and Water, but that did not work. I have also gave them pets and bigger rooms but that does not work either. Do you have any advice?


This happened to me a couple times before, where i accidently click a key combination and it hides the outliner + other panels Pressing CTRL UP / DOWN / LEFT / RIGHT does not bring anything back for me. And restarting blender doesn't help..

I would like to find a different solution to closing these windows without having to do the click and drag.


For example, I have a question about C++11.  Then, should I also tag the question with a c++ tag? Are there any guidelines on this kind of situations?  Also, if I don't mention the c++ tag, will my question's title be prefixed with c++11 - etc.?

In my retagging madness today, I came across a few questions tagged similar to the following:  [visual-studio], [visual-studio-2005]  My question is: should questions be tagged like this with both tags, or is it better to only apply the more descriptive/precise tag? How would this affect searching?    Another issue. With a tag such as [visual-studio], there's 2 additional levels of tags: [visual-studio-2005] and [visual-studio-2005-expres] (trailing 's' is not a typo -- tag length limit is in play), so if I have to tag a question with VS2005 Express and I should tag with all 3, I've burned up 3 of the 5 allowed tags just for the environment I'm using, which doesn't seem right. In fairness, these instances are probably rare, but certainly 2 out 5 tags can be significant sometimes, too.


The original question is just below. $$2+\frac{5}{3\cdot2!}+\frac{5\cdot7}{3^2\cdot3!}+\frac{5\cdot7\cdot9}{3^3\cdot4!}+\space...\space=\space?$$ I tried to express it with the summation notation but was really confused by the geometric series in the numerator. I then decided to use double factorial. I don't know if I made the correct thing to start with but that was all I could afford. $$2+\lim\limits_{n\to\infty}\sum\limits_{k=1}^{n}\frac{(2k+3)!!}{3^{k+1}\space\cdot\space(k+1)!}$$ I don't have the answer. Could you please explain how to solve this question? As you see, I couldn't really do much, so it would be great if you could clearly explain each step.

If $$\alpha=\frac {5}{2!3}+\frac {5\cdot 7}{3!3^2}+\frac {5\cdot 7\cdot 9}{4!3^3}+\dots $$  Find the value of $\alpha^2+4\alpha $.   The possible options are:   21 23 25 27   I think $$\alpha=\sum \frac {(2n+4)!}{2^{n+2}(n+1)!(n+2)!3^{n+1}}$$ but cannot think of what else to do.


I have a following problem: A meson is generated $h$ meters above the earth's surface and begins to move towards the earth with velocity $v$. Its (proper) lifetime is $t_m$.   What is $v$ if the meson is to reach the surface of the earth? How long did the meson live, according to a clock on the surface of the earth? According to the meson, how far away from the surface of the earth was it created?   I familiarized myself with formulas for time dilation and length contraction. If we attach a primed frame of reference to the meson, then  $$\Delta t = \gamma \Delta t'$$ $$\Delta x = \frac{1}{\gamma} \Delta x'$$  But then, what is $v$? Is it $\frac{\Delta  x}{\Delta t}$ or $\frac{\Delta  x'}{\Delta t'}$? Clearly the two aren't the same, but I thought the velocity is 'set in stone' so to speak, regardless of the frame of reference? So what is the meaning of each of those two quantities?

I cannot for the life of me figure out what I am doing wrong with this problem:  If a high speed particle travels a distance of 39 Km with a half life of 1 micro sec, what must its speed be to travel said distance? I keep getting Erroneous calculations.  $$\Delta t' = \Delta t\gamma = \frac{\Delta x}{v}\gamma$$  therefore, the speed observed by the neutrino or whatever is  $$\begin{gather}\Delta t' = 1 \times 10^{-6} s = \frac{39 \times 10^3 m}{v\sqrt{1 -\frac{v^2}{c^2}}}\\  \sqrt{v^2 - \frac{v^4}{c^2}} =39\times 10^9 \frac{m}{s}\\ - c^{-2} v^4 + v^2 - (39)^2\times 10^{18} = 0\end{gather}$$  So I solve this quartic equation and I get really strange results  $$v^2 = -\frac{1}{2} \pm \frac{\sqrt{1 - 4c^{-2}\times(39)^2\times 10^{18}}}{2}$$  Which always yields imaginary values for $v$. what did I do wrong? Should my $\Delta x$ be negative? I don't see why it would matter since I can define positive in any direction.  Below the problem is stated in its entirety: "The particle is unstable. It decays into other particles with a half-life of only t = 1 microseconds. That means that, even if it were travelling at the speed of light, it would only be able to travel 300 meters  before disappearing. However," continues Professor Smith, "we find plenty of these Bluto particles at the ground level. We believe that they are created in the upper atmosphere at an altitude of H = 39 km above the ground. How in the world can they reach the ground before decaying?"  "Ah", answers Professor Jones, "have you taken into account the time dilation factor? If the Bluto particles are created with a high enough initial speed, they could reach the ground during their brief lifetime."  How fast must the particles be moving to reach the ground? Express your answer as a fraction of the speed of light. You must be correct to the sixth digit in order to be marked correct.


I've always wondered why there was only one creature like yoda in the star wars movies. Was he really one of a kind or does he appear in other media?  I'm trying to determine if there are enough of his kind to divulge a race.

We never seem to see any beings of Yoda's species - except, of course, Yoda himself.  This leads us to the question of where the rest of the li'l critt'rs are. Yoda had to have parents, correct? So what happened to them? Was Yoda, put simply, just one of the last of a dying species?


Show that if $0<b<1$ it follows that $$\lim_{n\to\infty}b^n=0$$ I have no idea how to express $N$ in terms of $\varepsilon$. I tried using logarithms but I don't see how to find $N$ from this.

Prove that the $\lim_{n\to \infty} r^n = 0$ for $|r|\lt 1$.   I can't think of a sequence to compare this to that'll work.  L'Hopital's rule doesn't apply.  I know there's some simple way of doing this, but it just isn't coming to me. :(


What does the circle in d) and e) means? In this exercise, I have to find inverse matrix. $h:\mathbb{R}^3 \to \mathbb{R}^3$ is given by $$h(x,y,z) = (4x+y,x+z,-2x+3y+z)$$ (d) $g \circ h$ (e) $h \circ g$

I have two function $f$ and $r$, such that: $y = f(x)$, $r(y) = x$. I read that it means that: $f \circ r = I_{U}$, where $x \in U, y \in U$, where $U$ is a finite set. What does $f \circ r = I_{U}$ mean? What does this circle mean and how could i read all this writing $f \circ r = I_{U}$ ?


I was going for a pacifist playthrough, and so I used the tranquilizer rifle and stun gun almost exclusively.  During the Cloak & Daggers side-mission, I was aiming to incapacitate Double-T, with the first obstacle being the henchman sitting on the couch outside his apartment door. I took out my stun-gun and made short work of him, but as I was dragging him away from where he collapsed I noticed that he appeared to be dead:    This is the first time I've had someone die after shooting him with the stun gun. Just to try it out, I reloaded and shot him with the tranquilizer rifle, only to have him die again (maybe he has a severe allergy to being unconscious).  So, is this just some sort of weird glitch, or does this actually count as a kill, thus disqualifying me for the pacifist achievement?

So I shot a tranq dart into someone's head and I got the Merciful Soul bonus, but then when I go up to loot the corpse, his icon shows a skull, does that mean he's dead and I just screwed up my pacifist attempt?


I try the upper solution to avoid my Ubuntu server (32x) to sleep, but now i just can't enter it, after i reboot aparently something avoid it enter to the console, it start to boot but don't end.  in my case just shows the console while booting, but the one with very big Letters on it and not a chance of write anything on it, like the lines of console who apparead when is turned on, but don't leave that state.  i don't have any gui installed and i really preffer fix the problem through terminal  Any question? please do it  Thanks in advance  PS: i can't modify the "grub" back like it was before the change, so i can't revert the changes done.  My version is 12.04

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I usually play some random hits station while we play, but I'd like to play something that more envelops what we do in 5e. My party seems to play better when the music matches the mood.   Instead of, you know, like Taylor Swift's "love story" coming on while trying to have the BBEG come out and seem ominous...   What are some songs or soundtracks that other DMs or players have going during their campaigns?

Music is an essential component of my games. When running games set in the Star Wars universe, the music of John Williams adds a new dimension to the experience, both for me and for my players. Now that I'm starting a fantasy campaign, I'm a bit more uncertain about which music to use.  How do I create a soundtrack suitable for using in a fantasy campaign?  Specifically:   What sort of characteristics make for good back ground music? What makes for bad background music? What should I look for to get a fantasy feel? Which genres/sub-genres support fantasy games? What are good sources for fantasy background music?   A few notes:   Because the music will be used in the background of game sessions, most of the tracks should be one minute or longer, to avoid repetitive loops. Likewise, soundtracks with a variety of themes are preferred, so that they can easily support different modes of the game: exploration, combat, and chases, to name a few. Orchestral or acoustic music is preferred over music with vocals or electric instruments.


I was trying to edit source.list for apt-get install update and generated new source code from repogen.simplylinux.ch and I don't know what happened during editing but now when I type version then it says:    WARNING:root:could not open file '/etc/apt/sources.list'    version: command not found   and when I do apt-get install mtools then it says:    root@spider-laptop:~# apt-get install mtools Reading package lists... Done Building dependency tree        Reading state information... Done Package mtools 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 'mtools' has no installation candidate

There are now errors when updating and I cannot install most software due to a corrupted  /etc/apt/sources.list   file. Is there a copy I can download to replace it?  The file would be for Ubuntu 12.04 (Final Beta) in the United States.


I recently built a filter panel similar to .  My panel is different in that it can be collapsed out of the way to free up room for the results (see below)    I felt that the first letter of the title should basically remain in the same place as a user clicks to expand / collapse the panel so I went with option A but another developer thinks option B looks better.  I can't find anything official so I thought I'd ask here.  After collapsing a panel should the title read down, up or not matter either way?

When rotating text with css, should it be rotated clockwise or counter-clockwise?  Is one more readable than the other?  Counter Clockwise:       —    Clockwise:


I want to disable middle mouse button paste, but still be able to:   Close tabs by clicking it with the scrollwheel Open links in a new tab by clicking the link with the scrollwheel.   I tried , but that makes closing tabs and clicking links unusable.  This question is not a duplicate because in the other question they want to disable the middle mouse button completely.

I don't like having the middle mouse button paste, because I often end up with uncompilable code in Eclipse. How can I turn this off (in all programs)? I'm running Fedora.


Two human explorers land on a planet and encounter an alien. The alien tells them that long ago humans were a cruel and oppressive space-faring species. For example, they genetically engineered one subjugate alien-race to remove a limb. A long war was fought that had been thought to exterminate humans but it seems it failed. The alien kills the humans and examines their space-craft to discover the location of Earth but the data was automatically erased when the humans died.  n.b. The book is not "" by H B Fyfe.

So the story goes, humans in a spaceship search for an inhabitable planet, being surprised they found none in the vicinity of Earth. They find one, and it seems uninhabited. At the same time are observed by the aliens, who go down on the planet to meet them. The aliens sit them down and tell them a story about war and conflict that ruled the galaxy, and how all the sentient races in the galaxy got together and got rid of the race that tried to conquer all by blowing up their planets.  In the end you realise man is this terrible conqueror the aliens are talking about.


I know that if two groups are isomorphic, they have same number of elements of order n. But will the converse holds? I think it won't  as there are many group characteristicss like abelian or cyclic will also matter. But I can't come up with example.

Suppose $G$ is a finite group and I know for every $k \leq |G|$ that exactly $n_k$ elements in $G$ have order $k$. Do I know what the group is? Is there a counterexample where two groups $G$ and $H$ have the same number of elements for each order, but $G$ is not isomorphic to $H$? I suspect that there is, but I haven't thought of one.


I have a data set where I am interested in the regression line the best explains the upper bound of that data. As an example the subset of data 'df2' from 'df' below represents the best 4 points describing the upper bound that all the data lies under:  df <- data.frame(x = c(38,  45,  78,  88,  99,  103, 117, 117, 120, 148),               y = c(256, 226, 185, 198, 187, 89,  167, 160, 138, 85)) df2 <- data.frame(x = c(38, 88, 99, 117), y = c(256, 198, 187, 167)) plot(df) abline(lm(y~x, df)) points(df2, pch = "x", col = "red") abline(lm(y~x, df2), col = "red")     The nature of the data is that 4 data points on upper bound and with reasonable spread should return an R^2 > 98%. Ultimately I am interested in the x- and y-intercepts of the red regression line depicted in the plot. Any suggestion for a function or method that can achieve this would be greatly appreciated.

I am analyzing data on a health variable and its relation to age, gender, height etc. I am more interested in 90th percentile of the health variable, which can be called upper limit of 'normal'. How will this analysis be different from regular analysis where one is trying to find out factors predicting the value of health variable?


We believe that the standard model is only an effective field theory of its true UV completion. However, effective theories have dimensionful couplings and are not renormalizable. The standard model has dimensionless couplings and is renormalizable. So then how is the standard model both an effective theory but also renormalizable?  Edit: Is this the answer: if we have a theory with dimensionless couplings, then look at it on a lower energy scale, it will look like an effective theory with dimensionful couplings. But a "grand unified theory" won't have dimensionless couplings. It will have dimensionful couplings, perhaps with the size of the planck mass. So while the standard model might be an "effective theory" of the "grand unified theory," it has dimensionless couplings instead of dimensionful couplings, because the "grand unified theory" already had dimensionless couplings that are irrelevant at our scale.  Is that a correct answer?  Edit 2: My question is different from other "why is the standard model renormalizable" questions because I am asking why the standard model is renormalizable given that it probably is an effective field theory.

Effective theories like Little Higgs models or Nambu-Jona-Lasinio model are non-renormalizable and there is no problem with it, since an effective theory does not need to be renormalizable. These theories are valid until a scale $\Lambda$ (ultraviolet cutoff), after this scale an effective theory need a UV completion, a more "general" theory.  The Standard Model, as an effective theory of particle physics, needs a more general theory that addresses the phenomena beyond the Standard Model (an UV completion?). So, why should the Standard Model be renormalizable?


In my passport, my name is Firstname middlename1 middlename2 lastname, and in the ticket is LASTNAME/FIRSTNAME MR.  Will be a problem? I'll travel from Brazil to Bali, Indonesia and according to the agency I bought the ticket from, there's no problem and it's common.  The airline is Qatar Airlines and I have looked , which says that the passenger name can't be changed after the booking has finished.  But I don't know if it is a problem.

As per passport my name is Manish Kumar Ahuja, but by mistake I book a ticket with the name of Manish Ahuja. My middle name is not on the ticket. Can I fly on this ticket? Because the airline can't add the name and they say that the ticket is non-refundable.


While installing Ubuntu, I accidentally made a NTFS drive into EXT4 drive. Then, all the data of that drive was gone. Can I recover that drive and those data?  While using Windows 10, I have tried some softwares but, they were paid. I just want to recover that drive and those data.

About two weeks ago I had a problem with my PC that my brother wrote a question about at .  I still haven't solved the problem, so my PC is unusable now.  Now I think that it would be simpler to re-install both Win7 & Ubuntu than repair them, but there're some data on their partitions. I want to recover this data.  These partitions are not mountable for some reason. I don't know why.  sudo fdisk -l about the problematic partitions:     Device    Boot      Start         End      Blocks   Id  System /dev/sda1            2048     147912703    73955328   83 Linux /dev/sdb2            206848   174079999    86936576    7  HPFS/NTFS/exFAT   And in GParted:      And the error of the mount command:  Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   And the exact same message for /dev/sda1  How can I recover my data from those HDDs?  EDIT     I have tried to specify the type of the drive:  $ sudo mount -t ext4 /dev/sda1 /olddisk mount: wrong fs type, bad option, bad superblock on /dev/sda1,        missing codepage or helper program, or other error        In some cases useful info is found in syslog - try        dmesg | tail  or so $ sudo mount -t ntfs /dev/sdb2 /olddisk NTFS signature is missing. Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   EDIT     sudo ntfsfix /dev/sdb2 returns:  Mounting volume... NTFS signature is missing. FAILED Attempting to correct errors... NTFS signature is missing. FAILED Failed to startup volume: Invalid argument NTFS signature is missing. Trying the alternate boot sector Unrecoverable error Volume is corrupt. You should run chkdsk.


So, I answered a question a few days ago, and it was accepted.  Then today, the OP decided that it did not fit his requirements and removed my answer as the accepted answer.  He said that he did this to raise attention to his question again, but while being similar, his new is in fact a very different one.    Is there any way to discourage this kind of action, or is it in fact acceptable?

I'm not sure if there's already an existing term for this, so I'm inventing my own. (tl;dr: I call them "chameleon questions" because they change every time you submit or edit an answer.  If you're already intimately familiar with the phenomenon, please skip past the first set of bullet points to where I ask for recommendations.)  I think many of us have experienced this on occasion:  You open up a narrow-looking question, usually dealing with some specific error message.  The question probably contains a snippet of sloppy but not quite awful code; code indicating that the author, typically a new/low-rep user, possibly a , doesn't really know what they're doing.  I'm not trying to be condescending here, they're probably very intelligent and hardworking, but in this specific case, they're clearly in way over their head.  However, as a question, it's not really too bad.  The goal and problem are both clearly stated.  The code is formatted (sort of).  Mort was polite and checked their spelling.  The question looks answerable, although from a rep perspective* it's an obvious dead-end, it's had maybe 3 views in the past 30 minutes.  So you decide, you know what, this person took the time to write up the question properly, they deserve an answer, put on your good citizen hat and throw them a bone.  You slog through the ugly code, find the offending line, direct their attention to it and explain why it's wrong and how it needs to be fixed.  Later, they leave a comment saying that yes, that was indeed the problem and your answer helped them fix it (great!).  Oh, but, now there's another problem (uh-oh...). Something else is broken.  After letting out a long sigh, you read the comment and/or edited question, roll up your sleeves, and write up Take 2, hoping that's the end of it.  And of course it's not the end.  Now maybe the error is gone, but it's not doing what it's supposed to.  If you're anything like me, your patience is now starting to wear thin. It's lousy code and you didn't volunteer to help them rewrite their whole app.  And of course, the question still only has 12 views, and nobody has upvoted either the question or your answer, including the person you're helping, so this is turning out to be a genuinely thankless task in all respects.  Welcome to "Family Tech Support", Web 2.0 Edition.   * Which is of course just an arbitrary number that none of us care about. Not really, anyway. Not very much, at least.  So, here's where I get to my question.  At this point, do you:  Leave a comment, stating as politely as possible that you've done your best to help them answer the original question they asked, and if they have a new problem then they should start a new question?  (I did this once, and actually ended up with an accept, but I felt kind of guilty afterwards, I don't think anybody answered their 2nd question).  Bite the bullet and edit your answer a 3rd, 4th, 5th time, however many times it takes to resolve their issue, knowing full well that they may not even remember to accept the answer once you're done? (I may work for free on SO, but that doesn't mean my time is worthless.)  Just abandon the question, hoping that it will force Mort to start thinking for himself?  Something else?   I've tried all three of the above and none of them ever quite feel right. I do want to help, but at the same time there are a lot more "lucrative" questions I could be answering. And I don't mind spending a lot of time on an answer either, if the question is interesting or important to me, but debugging is dull work. I'd prefer not to reference specific questions here; I'm pretty sure that this is a shared experience, and my objective isn't to point fingers at "misbehaving" members.  I'm more looking for some practical advice on how to dig myself out of these pits of despair. Anybody have any other ideas?


In the Einstein's model of time-space bending, in the simplified version, the fabric of the Universe is in 2D, while the planets are in 3D. This is the first inconsistency that I think ruins the explanation of the model. You can't arbitrarily dimensionaly downsize one part and not the other, you get a dimensionaly inconsistent model. But that's the less problematic part.  The real problem for me to understand is the following: if a heavy planet bends the cloth and creates a slope... this means that there is another vertical gravitational field that pushes the planet down into the fabric in order to bend it. Furthermore, the light object (a satellite for example) then falls onto the heavy object, meaning it's going down the slope. In order to have something react to a slope, you need to have a vertical down-pulling field. This all means that we're explaining gravity by another (vertical) gravity, without which the whole metaphor just doesn't work.  I'm not saying Einstein was wrong. I'm just saying that I have a serious problem understanding this model, firstly because it's half 2D and half 3D, and secondly, more importantly, because it presumes another gravity through the entire metaphorical universe. Since all physicians in the world agree with Einstein's idea I presume it's accurate, but this model of explanation, if you ask me, fails heavily. Can anyone please help me understand the model?

I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general relativity there is this one illustration, which is being used over and over (image from Wikipedia):    I always thought that general relativity gives another way how you can describe gravity. However for this illustration to work, there needs to be another force, pulling the object down (referring to a direction in the attached image). If I put two non-moving objects in the image, what force will pull them together?  So where is my understanding incorrect? Or is general relativity not about explaining gravity and just describes how heavy objects bends spacetime (in that case the analogy is being used not correctly in my opinion)?    UPDATE Thank you for the answers and comments. Namely the XKCD comics is a spot on. I understand that the analogy with bent sheet of fabric pretty bad, but it seems that it can be fixed if you don't bent the fabric, but just distort the drawn grid.   Would you be so kind and answer the second part of the question as well - whether general relativity is explaining gravitational force. To me it seems that it is not (bending of spacetime simply can not affect two non-moving objects). However most of the time it is being presented that it does.


I try to adjust the size of my figure. However, the moment I do that, by adding plt.figure(figsize=(10,5)) I don't see the dots anymore. The reason I want to change the size is mainly because of ylabel is not shown the way it is now.    import pandas as pd import matplotlib.pyplot as plt import numpy as np from sklearn import linear_model  # Check out the Data df = pd.read_csv("https://s3.amazonaws.com/codecademy-content/programs/data-science-path/linear_regression/honeyproduction.csv") # print(df.head()) # print(df.columns)  prod_per_year = df.groupby(['year']).totalprod.mean().reset_index() # print(prod_per_year)  X = prod_per_year['year'] X = X.values.reshape(-1, 1) y = prod_per_year['totalprod']  plt.scatter(X, y) plt.xlabel('Year') plt.ylabel('Total production') plt.show()  # Create and Fit a Linear Regression Model regr = linear_model.LinearRegression() regr.fit(X, y)  # Print out the slope (regr.coef_) and the intercept (regr.intercept_) print(regr.coef_) print(regr.intercept_)  y_predict = regr.predict(X) plt.figure(figsize=(10,5)) plt.plot(X, y_predict) plt.show()

How do you change the size of figure drawn with Matplotlib?


I am trying to follow some instructions, that seem to be a multiple line command line argument.  Here it is:  You will need a couple of packages before getting to work. Install them using the following command:  Debian based Systems:  sudo apt-get install git build-essential cmake gettext kdeartwork libqwt-dev \ kdelibs5-dev libxtst-dev libqt4-sql-sqlite libphonon-dev libattica0.4 libattica-dev zlib1g-dev \ libasound2-dev julius libpocketsphinx-dev libpocketsphinx3 sphinxtrain libsphinxbase-dev \ libsphinxbase3   When I simply copy and paste that into the command line, and run it, the computer says:  Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package kdeartwork

When I try to install any package through the command line, I get an error.   $ sudo apt-get install <package> Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package <package>   Can anyone help me on this?


I'm facing the same (or similar) issue as described here:   Unfortunately I cannot try the provided solution (), as I fail to log in. I always get Login incorrect.  I already checked my password by typing it in as login name. Everything is correct. No caps, no num. I also have no problems getting to my desktop with my user name and password. Could it be due to my username Stefan Schmid with a space?  The System is 14.04 LTS. On the login screen there is still the menu bar. I even can get to settings. But thats about it. E.g: when I click on users, nothing happens.  What should I do?

If I login on my Ubuntu 14.04, I get the following desktop:  This weird behavior appeared after I executed sudo apt-get update && sudo apt-get upgrade and restarted my computer. Don't know why though.  To my Ubuntu I have tried the following (nothing seems to work so far)  Fix any broken packages:  sudo apt-get update sudo apt-get autoclean sudo apt-get clean sudo apt-get autoremove   Locate any broken packages and reinstall them:  sudo apt-get install debsums sudo apt-get clean sudo debsums_init sudo debsums -cs sudo apt-get install --reinstall $(sudo dpkg -S $(sudo debsums -c) | cut -d : -f 1 | sort -u)   Removing some compiz files:  rm -r ~/.cache/compizconfig-1 rm -r ~/.compiz   Purging of NVIDIA and installing NVIDIA-prime:  sudo apt-get install --reinstall ubuntu-desktop sudo apt-get install unity sudo apt-get purge nvidia* bumblebee* sudo apt-get install nvidia-prime sudo shutdown -r now   Compizconfig Settings Manager:  sudo apt-get install compizconfig-settings-manager  export DISPLAY=:0 ccsm  // Back to UI and enablement of Unity Plugin   Unity replace, which stopped at a while and did nothing afterwards  unity --replace   Some dconf reset  dconf reset -f /org/compiz/ unity --reset-icons &disown   Actually dconf did not work and I got this error:  error: Cannot autolaunch D-Bus without X11 $DISPLAY   Can anybody help me on that?    This is my hardware (hope it helps in any way):   Intel® Core™ i7-3770 ASUS GTX660TI-DC2-OG-2GD5 () ASUS P8Z77-V LX Corsair DIMM 8 GB DDR3-1600 Kit Samsung 830series 2,5" 256 GB (Windows is installed here) Seagate ST31000524AS 1 TB (3/4 are reserved for files; 1/4 is for Ubuntu (16GB swap included))


Let's discuss what you're looking for exactly. OR Let's discuss what you're exactly looking for. The general question is : where to place the adverb in such a phrase ? As a non native it's hard to know what's correct or sounds better.

I want to ask a question whose meaning is "what is the exact way in which X works?". Where is the most appropriate place for the adverb "exactly"?   How exactly does X work? How does exactly X work? How does X exactly work? How does X work exactly?


This is my first time really getting to know Linux. I'm booting Ubuntu 12.10 on my HP G65 Notebook, which is pre installed with Windows 7 64 bit, from a live USB. The HP loads just fine and proceeds to try to boot Ubuntu but it freezes up on a black screen with syslinux 4.06 edd 2012-10-23 copyright (c) 1994-2012 H. petter Anvin et al and a blinking bar under it at the top.   I'm tired of windows and I want something far more stable. And try to keep the talk on a noob understandable level.

I am trying to install linux on my laptop, a Toshiba Satellite C6550-S5200. I did it once but something happened so I removed it then I had to destroy all data on hard drive so now I have nothing on it. Well I got a iso file burned to a CD and to a flash drive. With the flash drive I get.   SYSLINUX 4.06 EDD 4.06-pre7 Copyright (C) 1994-2012 H. Peter Anvin et al  With the CD it will start booting it but somewhere loading it up, the dots turn all orange and stay that way and my CD drive turns quiet.  Oh and some more info the images work because I tried loading them up on another pc and it worked just fine.  I manage to get the CD to boot I just had to let me pc boot up first then insert the CD and have it boot the CD then. Once I get done installing ubuntu it works fine but I have to leave the PC on 24/7 for if I turn it off the PC will freeze 5-10 seconds after booting back up no matter how I install it.


Here is the command I have used to check my bash shell for the Shellshock bug:  env x='() { :;}; echo vulnerable' bash -c "echo this is a test"   Can anyone please explain the command in details?

Recently, there have been news going around regarding "CVE-2014-6271" (See ), which is a vulnerability in Bash. How do I know if I am affected by this, how can I fix it, and why should I care?  This is designed as a canonical answer for this vulnerability, due to its scope and severity.


I'm looking for something different from . I'm considering a scenario in which one intends to use a certain tactic to defend oneself against some enemy. However, before the tactic can be used, it is stolen by the enemy and used against the person him/herself.  Example: Alex told the plagiarizer he'd sue them unless they delete the video. However, that only prompted the plagiarizer to ______ with a defamation lawsuit.

I'm looking for a word to describe using someone's own tactics against them. A formal word is preferable but a colloquialism will work as well.


I've got this function and I need to find the limit. I have tried multiple things. I've replaced $\cosh(x)$ with $e^x+e^{-x}$ and calculate on that. But it seems like no matter what I do, I always gets a problem with $\infty$.  Here is the function: $\lim\limits_{x \to \infty}\frac{1}{\cosh(x)}+\log\left(\frac{\cosh(x)}{1+\cosh(x)}\right)$

How can I - without using derivatives - find the limit of the function  $f(x)=\frac{1}{\cosh(x)}+\log \left(\frac{\cosh(x)}{1+\cosh(x)} \right)$  as $x \to \infty$ and as $x \to -\infty$?  We know that $\cosh(x) \to \infty$ as $x \to \pm \infty$ thus $\frac{1}{\cosh(x)} \to 0$ as $x \to \pm \infty$.  And I imagine that $\frac{\cosh(x)}{1+\cosh(x)} \to 1$ as $x \to \pm \infty$ thus $\log\left(\frac{\cosh(x)}{1+\cosh(x)}\right) \to 0$ as $x \to \pm \infty$.  Is this approach sufficiently formal?  Any help is appreciated.


Given a sequence of functions $(f_n)$, with $f_n : [a, b] → \mathbb{R}$ we say that it is uniformly Lipschitz if there exists $K > 0$ such that for every $n$ and every $x, y ∈ [a, b]$ we have  $|f_n(x) − f_n(y)| ≤ K|x − y|$  Prove that if $f_n → f$ and (f_n) is uniformly Lipschitz then $f$ is Lipschitz (i.e. there exists $M > 0$ such that for every $x, y ∈ [a, b]$ we have $|f(x) − f(y)| ≤ M|x − y|)$.  I have tried the triangle inequality, as in adding $|f_n(x) − f(x)|$, $|f(y) − f_n(y)|$, $|f(x) − f(y)|$ is greater than $|f_n(x) − f_n(y)|$, does this help?

Given $f_{n} : [a,b]\rightarrow \mathbb R$ is uniformly Lipschitz and $f_{n}\rightarrow f$, how can I show that $f$ is Lipschitz?  $f_{n}$ is uniformly Lipschitz $\leftrightarrow \exists K > 0$ such that for all $n$ and for every $x,y\in [a,b]$ we have $|f_{n}(x)-f_{n}(y)| < K|x-y|$.  $f_{n}\rightarrow f \leftrightarrow \forall~\epsilon>0~~\exists~N$ such that $\forall~n>N$ we have $\mid f_{n}(x) - f(x)\mid<\epsilon~~~(=\mid x-y\mid?)$  Then we have  \begin{align} |f(x)-f(y)| &\leq |f(x)- f_{n}(x)| + |f_{n}(y)-f(y)| + |f_{n}(x)-f_{n}(y)| \\ &\leq |x-y| + |x-y| + K|x-y| \\ &\leq (K + 2) |x - y| \end{align}  which shows that $f$ is Lipschitz. Can anybody tell me if this makes sense? Sorry if layout is poor.


Which of these is correct?      "If one or more of these situations apply to you ..."   or   "If one or more of these situations applies to you ..."   I think that "more" takes precedence over "one," so I would use the plural, "apply." Am I right?

Should the phrase be "one or more is...", or "one or more are..."?


This rather inelegant method takes an input array of objects and outputs a string result, which is the result of ToString() for each element, space separated.   string Format(object[] args) {    var res = string.Empty;    foreach (var o in args)    {       res += o.ToString();       if (o != args.Last())          res += " ";    } }   Surely there is a C# method hidden somewhere to do this type of operation, or if not, a more elegant way to write it using Linq? Another concern with how I have written this method is the garbage generation by building the string incrementally.

Is there any easy LINQ expression to concatenate my entire List<string> collection items to a single string with a delimiter character?  What if the collection is of custom objects instead of string? Imagine I need to concatenate on object.Name.


I have this A linear congruence is given by 2689x ≡ 3901 mod 4001. i. Show that the solution of the linear congruence exits. ii. Compute the general solution of the linear congruence. iii. Compute the least positive integer x satisfying the linear congruence and check your solution. I need help on this using Euclidean Algorithm. Also, reference to know this more will be appreciated, Thanks!

What is the best way to solve equations like the following:  $9x \equiv 33 \pmod{43}$  The only way I know would be to try all multiples of $43$ and $9$ and compare until I get $33$ for the remainder.  Is there a more efficient way ?   Help would be greatly appreciated!


The update fails with the following error messages:  bob@Proliant-Server:~$ sudo apt-get dist-upgrade Reading package lists... Error!  E: Encountered a section with no Package: header  E: Problem with MergeList /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_universe_i18n_Translation-en  E: The package lists or status file could not be parsed or opened.   I have run the following commands to no avail:  sudo apt-get clean sudo apt-get update   I am getting desperate! Any suggestions would be appreciated! TIA

The computer gave me this output in a window:  E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_natty_main_binary-i386_Packages E: The package lists or status file could not be parsed or opened.   How can I fix this?


Some new users ask questions and I sometimes reply in the comments. Also, some other users also comment on questions.   We will just comment and close the URL of the question, and if the OP comments again, we don't get the notification because he didn't tag any usernames. This way there are a lot of chances that they may miss help.  How can we avoid this? Can the system make it mandatory to add tags in the comments?

Lots of the first questions come with insufficient information, context and eventually left unanswered after days.  While other users comment below requesting more info, the inexperienced OP usually reply without @ believing it works exactly the same as facebook, but no one receives notification.   One or two days later, the OP feels really lost on the site, and convinced his/her question is so hard to be solved or the people on the site just trend to ignore him/her.  A little extreme example today on stackoverflow, a user deleted the question posted yesterday, and posted again to get other's attention. Simply because no one being notified.   Current  will notify other users when OP missed @ in such cases:   OP comment on an answer, the author of the answer will be notified. (not applicable, as most unnotified comments are under the question.) OP comment under his own post, and exactly one person commented. (not applicable in most cases, as a fuzzy question usually start a little discussion below.)   Which means basically, there won't be any notification for previous people who commented.   So is it possible to enforce (at least shows a tip) the new user comment with a @ in their first few comments?


My wife is learning English and she wrote the following sentence.  "When highlighting the large profit losses, the author identified a decrease in sales at Tasty Cream that is the only ice cream store in town."   She believes that this sentence is grammatically correct. However, I believe that using "Tasty Cream, which is the only ice cream store in town" or "Tasty Cream, the only ice cream store in town" is grammatically correct. Can someone help to explain which usage is correct and why? Thank you!

When is it appropriate to use that as opposed to which with relative clauses?


My large secondary HDD that I use for storing all my steam games has once again up and decided that it needs to be it's own person again and I no longer have execute permissions for it. so all my steam games look as though they were uninstalled in one reboot. I'm sure I can figure out how to get those permissions back with a quick google search.  but, why? why did it happen at all and why does it keep on happening? first it took away my read/write permissions, then it took away my execute permissions. is there something in the ubuntu updates that I don't know about and I should be running a command after every update?

I have got an external hard disk TOSHIBA 1TB USB 3, the permission is always READ ONLY.  fdisk -l (output) :  Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xf2198b37     Device Boot      Start         End      Blocks   Id  System /dev/sda1   *        2046   362369023   181183489    5  Extended /dev/sda3       362371072   976771071   307200000    7  HPFS/NTFS/exFAT /dev/sda5            2048      976895      487424   83  Linux /dev/sda6          978944   362369023   180695040   83  Linux  Disk /dev/sdb: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xeba6fb57     Device Boot      Start         End      Blocks   Id  System /dev/sdb1           16065   312576704   156280320    f  W95 Ext'd (LBA) /dev/sdb5           16128   312573708   156278790+   7  HPFS/NTFS/exFAT  Disk /dev/sdc: 1000.2 GB, 1000204885504 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525167 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x297c35de     Device Boot      Start         End      Blocks   Id  System /dev/sdc1              63  1953520064   976760001    7  HPFS/NTFS/exFAT   How can I change the owner and permission of this hard drive ?