Learning about group velocity, phase velocity and particle velocity

I am studying quantum physics and I would like to know a bit more in detail about , particle velocity and .  Can you suggest some books/online resources where I can learn the same.


What is a recommended strategy on exercises in a mathematical textbook at graduate level?

When I read a mathematical textbook at graduate level to learn and master a particular subject that I am unfamiliar with, I always struggle with the strategy on the exercises. Sometimes I spent one hour on one exercise problem without making any progress. Sometimes I skip exercise problems with guilt and worried that I may not have learnt the material well. I can think of the following possible strategies on exercises:   Ignore all of them. Just focus on reading the main body of the textbook. Set a time limit. Say for every hour I spent on reading the main body, I spent twice much time on solving exercise problems. I try to solve whatever I can within two hours and skip the rest. Never move on to a new session unless I have solved all exercise problems in the previous session. If I get stuck, spend hours working on it and if still no success, look it up or ask somebody until I understand the solution. Spend a reasonable amount of time on each problem and if I could not solve it, read the solution from a solution manual. This strategy seldom works as for most books on graduate level, solution manuals are unavailable.   What strategy do you recommend? I personal feel that Strategy 3 is the most time-consuming but it is also the only one that does not bother my conscience. But because it consumes a huge amount of time, I am not sure if it is wise to adopt it.


Is there any way to draw an image to use 4 points rather than 3 (perspective warp)

Drawing a parallelgram is nicely supported with Graphics.DrawImage:  Bitmap destImage = new Bitmap(srcImage.Width, srcImage.Height); using (Graphics gr = new Graphics.FromImage(destImage)) {     Point[] destPts = new Point[] { new PointF(x1, y1),          new PointF(x2, y2), new PointF(x4, y4)};     gr.DrawImage(srcImage, destPts);   How, do you do 4 points (obviously the following is not supported, but this is what is wanted):  Bitmap destImage = new Bitmap(srcImage.Width, srcImage.Height); using (Graphics gr = new Graphics.FromImage(destImage)) {     Point[] destPts = new Point[] { new PointF(x1, y1), new PointF(x2, y2),         new PointF(x3, y3), new PointF(x4, y4)};     gr.DrawImage(srcImage, destPts); }


If $x,y,z$ are positive numbers, then prove that $\frac {x}{x+y} + \frac{y}{y+z} +\frac {z}{z+x} \le 2$

If $x$, $y$ and $z$ are positive numbers, then prove that $$\frac {x}{x+y} + \frac{y}{y+z} +\frac {z}{z+x} \le 2.$$   Though I have solved a lot of problems on AM-GM inequality, I am unable to solve this one. I am also not showing my working because I do not think that they will be of any help.


Im a newbie in Apex and im developing a page using Visualforce.  My string format is always like this "xx-xx-999999". In this format I need to get only the integer. For example the string is  "RO-W1-445567". I want to get only the integer 445567 in the string. Can someone willing to share a piece of apex code in my problem.  Your help is vey much appreciated.  Thanks in advance!  Ferdie Banu


egrep command usage to find lines starting with one character that also contain some string

Let's say I have a file which has some ls -l output:  waaa- foo.pdf -bbb- foobar.pdf -ccc- foobar waaa- foobar   I'd like to get just the first line   waaa -foo.pdf   as the final result, and I'm trying:  egrep -E "^w" .file | egrep -E "*.pdf"   Is there any way to combine these two searches?


I can't center horizontally a h6 (or any) tag inside a flex div. I think I've tried all approaches align-, justify-:self, items, content, but nothing works! I just want to place a div with 80% of its size and put text inside it, why is it supposed to be that hard?

I won't alignnnnnn


ABCDE is a regular pentagon, find angle CFD considering figure provided

As for the picture below, in which ABCDE is a regular    pentagon, find angle CFD. (List of problems for math olympics preparation)     Attempt: As ABCDE is a regular pentagon, all sides are equal and internal angles for the pentagon are $108^\circ$. So the angles FED and CBF are $84^\circ$. And angle BFE is $156^\circ$. But not seeing how to find a way to compute CFD.   Hints and solutions welcomed. Sorry if this is a duplicate.


Why doesn't Stack Exchange open links in a new tab?

It's simple to add an attribute to a hyperlink as target="_blank" - but Stack Exchange prefers to open the website in the same tab.  Every time as a user, I need to take care to open in a new tab, so that I can keep browsing other answers. This is mostly problematic when some one quotes another link in an answer - so you have not yet finished reading up the solution, but would be interested to check out that link as well.  Any of you have experienced this?


How many digits does the integer zero have?

Should zero be classified as having no digits, or 1 digit?


In a finite ring $R$ with identity show that $ab =1$ implies $ba = 1$, where $a,b \in R$.  I am having difficulty in doing this since there is no condition that there is no zero divisors and how will I use the finiteness of the ring!!


I use curl to submit sitemap but doesnt get reflection in webportal

this is TWO things confused me that how should I submit my sitemap.  First. It is understood that a sitemap can be submitted with cURL.   However, every time the sitemap submission doesnt reflect in the web portal. The timestamp in the webportal only shows the time I submit the sitemap in through the webportal.  Why they are different? Is submitting via curl working?  Second I found that google only crawl my website just after the first time I submit the sitemap. I update my site and sitemap regularly, and hoping google can crawl my site. However, it seems that google never come back.  What is wrong with these?   If you can see the picture, you will see there several peaks just after I submit the sitemap through Search Console. If you leave it alone, then it turns to be flat.


Is it possible to learn about an event that occurred outside of your observable universe?

I have mixed intuitions about this.  On one hand, nothing can travel faster than the speed of light and if there is enough space between you and an event then a signal will get stuck in the middle of nowhere traversing an ever-expanding void.  But, on the other hand, it seems reasonable enough that we could share information with other distant observers. That coupled with the fact that every observer has their own observable universe centered on them suggests to me that it would be possible to transmit an account of an event that another observer could never experience firsthand. While the information would have to travel farther than the radius of an observable universe, no individual particle would have to.    Would we be able to learn about something outside our observable universe if someone sent us pictures of, for example, the cosmic background radiation of their observable universe? Is this even a possibility?    Edit: To clarify, I'm talking about an observable universe limited by the  caused by the expansion of space and not the  caused by how far particles could have traveled given the age of the universe. As it stands right now, a mediator wouldn't be able to see anything novel since, as HDE226868 points out, our Particle horizon would have expanded to encompass the event by the time their forwarded signal would have reached us.    Edit2: Several answers have stated that any mediator would have been taken outside of our observable universe by the time it was able to transmit anything novel. But, is that going to always be the case? I was under the impression that gravity was sufficient to counteract the expansion of space to bind galaxies together. Is it unreasonable to suppose the existence of a mediator that has the appropriate velocity and acceleration to maintain a constant position relative to us for an arbitrary length of time despite the expansion of space?  Perhaps the movement of such an object has a relativistic effect on its observable universe?    Edit3: I think I figured out a good lead. While the Particle horizon is a ball around every observer and based on particles just not having had enough time to travel, the Future horizon is based on redshift which in turn is based on relative velocity among other things.  $$1 + z = \sqrt{\frac{1 + \frac{v}{c}}{1 - \frac{v}{c}}}$$  This suggests to me that two observers at a fixed position relative to each other (i.e. ) will have the same Future horizon due to the Doppler effect. However, there seems to be some room to reduce redshift back from infinity with some engineering.  For instance, a telescope in orbit around a planet would be able to see farther while pointing prograde than anyone on the planet since its relative velocity to distant events would be lower and signals would be blueshifted back up from infinity. This actually seems to suggest that a mediator could peer beyond our Future horizon for us.  However, there are some other factors that go into redshift other than the Doppler effect. Gravity wells and the expansion of space also have an effect. But, would these other effects frustrate this scenario?


Convergence of the $\sum_{n=1}^{\infty}n^3b_n^3$ where $b_n=\int_{-\pi}^{\pi}f(t)\sin (nt)\ dt$.

Let $f\in C^1[\pi,\pi]$. Define, for $n\in \mathbb{N}$, $b_n=\int_{-\pi}^{\pi}f(t)\sin (nt)\,\mathrm{d}t$. Which of the following statements are true?? a) $b_n\to 0, $as $n\to \infty$ b) $nb_n\to 0,$ as $n\to \infty$ c) The series $\sum_{n=1}^{\infty}n^3{b_n}^3$ is absolutely convergent.   Option a) is true by Riemann-Lebesgue Theorem but what about c)  ???I think b) is false ...


I have the 1.3 update and it's 2019 but it still doesn't work.i have defeated the golem about 20 times now and the lunatic cultist didn't spawn. Please help!


You learn in algebra that  $$\sqrt{ab}=\sqrt{a} \sqrt{b}$$ and that  $$\sqrt{\frac ab}=\frac {\sqrt a}{\sqrt b}$$ You also learn to never make the fatal mistake of thinking $$\sqrt{a+b}=\sqrt{a}+\sqrt{b}$$  However, I am wondering if there is a rule for $\sqrt{a+b}$. I would think it would be pretty complex, if it exists at all.  $$\sqrt{a+b}=\text{?}$$


Home button broken and Notification Center stuck

my home button on my ipod touch 5th Gen has been broken for  while so I have been using assistive touch. Earlier on my notification centre got stuck half way down the lock screen, making my ipod completely unusable.   I tried turning it off but the notification centre is blocking the slider and obviously I can't restart it since my home button is broken. Has anyone got any solutions? It's an absolute nightmare!


If Voldemort planned to make 7 Horcruxes and he did not plan for Harry to be one shouldn't there be another one?


Prove: $\operatorname{rank} A \leq 1$ iff $A=xy^T$ for some $x,y \in \mathbb{R}^{n \times 1}$.

Let $A \in \mathbb{R}^{n \times n}$. Then $\operatorname{rank} A \leq 1$ if and only if $A = xy^T$ for some $x, y \in \mathbb{R}^{n \times 1}$.  Need help. I can't find sufficient facts nor theorems to support my proof on the statement.


how do you compare two folders and copy the difference to a third folder using a shell script

#!/bin/sh # This is comment! echo Hello World for file1 in /C:/Users/shubham.tomar/Desktop/Shell/Test1/*;  do filename1=$(basename "$file1") echo $filename1 echo "------------------------" for file2 in /C:/Users/shubham.tomar/Desktop/Shell/Test2/*; do filename2=$(basename "$file2") echo $filename2 if [["filename1" = "filename2"]]; then echo "---File matched---" else mv -f /C:/Users/shubham.tomar/Desktop/Shell/Test2/$filename2 /C:/Users/shubham.tomar/Desktop/Shell/Moved/ fi echo "--------------File Moved-----------" done done   **  NOTE ABOUT PROBLEM  **  There are some files in a particular path for ex: Desktop/Test1 and Downloads/Test2 I want to write a shell script to move all the files present in Test2 and not in Test1 to a path for ex: Documents/MovedFiles  files may be of any type


Convert OSM File to get addresses using Osm2pgsql

I am working to covert OSM File to get all building's informations in the city.   I am using osm2pgsql package to transform the data. Now I am confused as I have 5 tables :      - planet_osm_point    - planet_osm_line    - planet_osm_roads    - planet_osm_polygon     I am confused now, how can I get buildings' informations from these tables. What do every table represent ?


Can anyone please tell me how to post code in this site? whenever i am trying to post code here I am getting some format error. It is saying like leave 4 lines or something like that.I am not getting it. Please help me. I am having some code problem which I want to post.


I'm trying to use the \begin{center} command twice on the same page, but weirdly it's not working, the second time it gives trouble. When I take it away from the first time, then the other one does work fine. Some code of a simple case to illustrate:  \documentclass{report}  \begin{document}  \vspace*{2em} \begin{center} \section*{Abstract} \end{center} \noindent bla bla   \vspace*{2em} \begin{center} \section*{Acknowledgements} \end{center} \noindent bla bla  \end{document}   Then the error I get is: ! LaTeX Error: Something's wrong--perhaps a missing \item. Which points to the second \end{center}. If I don't use centering of the first heading, but keep the centering for the second, then everything works fine.   Thanks in advance.


Do I really have to specify the width of my wrapfigure twice?

I'm trying to add a figure to my document. Because I want text to wrap around it, I use the wrapfigure environment:  \begin{wrapfigure}{r}{1cm}   \begin{center}     \includegraphics[width=1cm]{"My figure"}   \end{center}     \caption{A caption of my figure} \end{wrapfigure}   As you can see, I want my figure to be shrunk down (the file is quite large) so I set the width to 1 cm. But now I must also tell the wrapfigure to be 1 cm wide. Why can't wrapfigure just automatically be as wide as the figure it contains?


I might have been staring at the computer screen too long today and looked over something small but why can I not target these individual cells? (a1, a2, a3, etc...)

             sdf

   CSS:    div.row-a div.a div.1 {     border: 1px solid green;     margin-left: 5px;     margin-top: 5px;     background-color:red;     height: 50px;     width: 50px; }   jsFiddle:


I have at least 75 rep. I don't see any link underneath the comments to start a bounty:


Antiparticles travelling backward through time

Could someone please explain to me Feynman and Wheeler's theory of waves acting forward and backward in time?   I have read about their idea of an antiparticle behaving as a particle travelling backward through time, but cannot see how no paradoxes emerge.


Can instantiate a virtual object on the heap, but not on the stack?

Let me preface this by saying I'm coming from a Java background, so please forgive me if I've made some stupid mistake here....  I'm writing a C++ library that I would like to make compatible with both Arduino as well as the RaspberryPi. Most of the code is just clean, standard C++, but a few functions are hardware-specific (GPIO calls, for instance). Being from a Java background, I thought, I'll just create a HAL interface that defines those hardware-specific functions, and then I can create implementations of that interface for the RPi and Arduino, only to find out that interfaces are not a thing in C++ and you have to use virtual methods instead. Please see the bottom of my question for my source files.  However, when I went to actually use this, I discovered something quite strange: using the HAL on the heap compiles, but using it on the stack does not  //THIS DOES NOT COMPILE MyLibraryHAL hal = HAL_RaspberryPi(); hal.someHwSpecificFunction(65);  //BUT THIS DOES MyLibraryHAL* hal = new HAL_RaspberryPi(); hal->someHwSpecificFunction(65);   The error is: src.ino:67: undefined reference to MyLibraryHAL::someHwSpecificFunction(unsigned char).  Why is this? Is this just a feature of how virtual methods work? Or is there some concept I'm missing here?    MyLibraryHAL.h  #include <stdint.h>  #ifndef MyLibraryHAL_h #define MyLibraryHAL_h  class MyLibraryHAL {     public:         virtual void someHwSpecificFunction(uint8_t param); };  #endif   HAL_Arduino.h  #include <stdint.h> #include "MyLibraryHAL.h"  #ifndef HAL_Arduino_h #define HAL_Arduino_h  class HAL_Arduino : public MyLibraryHAL {     public:         void someHwSpecificFunction(uint8_t param); };  #endif   HAL_Arduino.cpp  #include <stdint.h> #include "HAL_Arduino.h"  void HAL_Arduino::someHwSpecificFunction(uint8_t param) {     //do things }   HAL_RaspberryPi.h  #include <stdint.h> #include "MyLibraryHAL.h"  #ifndef HAL_RaspberryPi_h #define HAL_RapsberryPi_h  class HAL_RaspberryPi : public MyLibraryHAL {     public:         void someHwSpecificFunction(uint8_t param); };  #endif   HAL_RaspberryPi.cpp  #include <stdint.h> #include "HAL_RaspberryPi.h"  void HAL_RaspberryPi::someHwSpecificFunction(uint8_t param) {     //do things }


lightning:recordEditForm onSuccess eventhandler Problem

I'm trying to catch the onsuccess event of a lightning:recordEditForm , because I need the Id of the record created. I'm not able to get that Id, how can I do that?  Thank you for your help. Below you'll find my code.  Component:
                 <lightning:recordEditForm aura:id="createContestForm" objectApiName="Case" recordTypeId="{!v.recordTypeId}" onsuccess="{!c.onSuccess}" onerror="{!c.onError}" onsubmit="{!c.onSubmit}">                     <lightning:messages />                          <lightning:inputField fieldName="Scope__c" value="Penale" />                         <lightning:inputField fieldName="Type__c"  value="Contestazione"/>                         <lightning:inputField fieldName="Subtype__c" value="{!v.casesubtype}" />                         <lightning:inputField fieldName="Description" />
                             <lightning:button aura:id="submit" variant="brand" class="slds-m-top_small" type="submit" label="Create" />
                  </lightning:recordEditForm>
   Controller:  // Intercept the sucess event     onSuccess  : function(component, event, helper) {         //event.preventDefault();          console.log('****onsuccess event****' , event);         var params = event.getParams();         console.log('response*****',params.response.Id);       },   Just for clarify I see 'response***** undefined' inside the browser console.


Does SEO value pass through canonical links pointing to another domain?

I have a relatively new price aggregation website (online for about one month). Part of it was also adapted (custom header/footer) and included into an older site, on a different domain, which already has a Google PageRank,  and domain authority.  In order to prevent duplicate content and to promote the main website, the integration contains canonical-url links on the old website pointing to the respective website pages on the new domain.  From a SEO point of view will any rank juice be passed from the older website and domain (which contains the integration) to the new one through the canonical links? Or is it better to just add "dofollow" links from the integration to the main website?


Running Windows Steam on Linux (Using Wine)

I just installed Ubuntu for the first time and am trying to figure a way to play Windows games on Linux. I've read you need to use Wine, and I'm just wondering how exactly I go about doing this correctly. I've read a lot of conflicting information.


Please help me solve this problem:  Let $X$ and $Y$ be independent standard normal random variables, let $Z$ have an arbitrary density function, and form $Q = \frac{X + YZ}{\sqrt{1+ Z^2}}$. Prove that $Q$ also has a standard normal density function.   Thanh you


can anyone tell me the transfer function for speed control of bldc motor using PI controller


Bayesian modeling: likelihood function for continuous random variables, why is it not always 0?

For continuous random variables, evaluating p(x) for a specific value of x is always 0 as show ,  and . So when we're calculating the likelihood for a random variable X that is represented by a continuous distribution we have:  $$ P(𝜃 \mid X) = P(x_1, x_2 ..., x_n \mid 𝜃) = \prod\limits_{i=1}^n = p(x_i \mid 𝜃) $$  There are two ways I consider thinking about.  1) The first is the intuitive definition of likelihood, e.g. how probable is a set of n draws for random variable X. Intuitively the likelihood seems like it calculates the probability of n draws occuring which, for any continuous random variable would be zero. This does not make much sense to me.  2) If we consider a gaussian distribution of µ = 0 and 𝜎 = 1 then p(0) = 0.4. This number doesn't represent anything concrete, but when used in the likelihood calculation, can serve as a relative reference for which model parameters 𝜃 fit our data better. In this scenario, likelihood is a bit of a misnomer as it isn't actually the probability of getting our observed data, but is a number that only draws meaning in reference to other likelihood calculations.    makes some really good points about interpreting a density function as density and not probability, which suggests that likelihood is indeed a bit of a misnomer. It's also somewhat confusing that the likelihood is expressed in terms of p(x), which I read as probability of x occurring.


Can I download an older version of an app from the App Store?

I want to download an older version of the Disney Now iOS app. The version I have installed is currently up to date, but I want one that is older.  Is there a way to do that?


Intersection of the empty set does not exist.

Let $S\neq\emptyset$ a set. Then $\bigcap S$ exists because it can be written in the form $\{x\in\bigcup S|x\in B~ \forall B\in S\}$ and we only have to use the axiom of union and Schema of Comprehension. But what happens when $S=\emptyset$? Given that $\bigcup\emptyset=\emptyset$ then we'd have $\bigcap S=\{x\in\emptyset|x\in B~ \forall B\in\emptyset\}$. How do I prove that this set does not exist?


Changing text colour of a text view using a spinner

So I am attempting to use a spinner to change the text colour of a message in a text view. However, when I attempt to use the function attached to my button click the activity crashes. I have attached the relevant part of the java code and the xml file  import android.content.Intent; import android.graphics.Color; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Spinner; import android.widget.TextView;  public class Colour extends AppCompatActivity {  private Spinner mySpinner; public static final String EXTRA_MESSAGE = "message"; @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_colour);     Intent intent = getIntent();     String messageText = intent.getStringExtra(EXTRA_MESSAGE);     TextView messageView = (TextView)findViewById(R.id.message);     messageView.setText(messageText); }  public void change(View v){     String text = mySpinner.getSelectedItem().toString();     TextView newColour = (TextView) findViewById(R.id.message);     if(text == "Red"){         newColour.setTextColor(Color.RED);     }     if(text == "Blue"){         newColour.setTextColor(Color.BLUE);     }     if(text == "Green"){         newColour.setTextColor(Color.GREEN);     } }   XML file:  <TextView     android:textColor="#000000"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:id="@+id/message" />  <Spinner     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:entries="@array/colours"     android:layout_centerHorizontal="true"     android:layout_marginTop="16dp"     android:id="@+id/spinner" />  <Button     android:text="HOME"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:id="@+id/button"     android:onClick="home"     android:layout_alignParentBottom="true"     android:layout_centerHorizontal="true"     android:layout_marginBottom="52dp" />  <Button     android:text="changeColour"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:id="@+id/button4"     android:layout_above="@+id/button"     android:layout_alignStart="@+id/button"     android:layout_marginBottom="101dp"     android:onClick="change" />


Since security is always something that is a concern, is it fine to just use the following method whenever I need to clean data that I don't know is safe?  function clean_data($input) {   return mysqli_real_escape_string($cxn, htmlspecialchars(strip_tags(trim($input)))); }   Or is something that I shouldn't do?


How much does a gigabyte worth of data physically weigh on a hard disk?

What is the physical weight of one gigabyte of memory/storage? Lets say this is on a hard disk.  What is the weight associated with the atoms that are actually storing the data on the disk?  How has this value changed as densities of disks have increased?


I believe that many of you know about the moving sofa problem; if not you can find the description of the problem .     In this question I am going to rotate the L shaped hall instead of moving a sofa around the corner. By rotating the hall $180^{\circ}$ what remains between the walls will give the shape of the sofa. Like this:    The points on the hall have the following properties:  \begin{eqnarray} A & = & \left( r\cos { \alpha  } ,t\sin { \alpha  }  \right)  \\ { A }' & = & \left( r\cos { \alpha  } +\sqrt { 2 } \cos { \left( \frac { \pi  }{ 4 } +\frac { \alpha  }{ 2 }  \right)  } ,t\sin { \alpha  } +\sqrt { 2 } \sin { \left( \frac { \pi  }{ 4 } +\frac { \alpha  }{ 2 }  \right)  }  \right)  \\ { B } & = & \left( r\cos { \alpha  } -\frac { t\sin { \alpha  }  }{ \tan { \left( \frac { \alpha  }{ 2 }  \right)  }  } ,0 \right)  \\ { B }' & = & \left( r\cos { \alpha  } -\frac { t\sin { \alpha  }  }{ \tan { \left( \frac { \alpha  }{ 2 }  \right)  }  } -\frac { 1 }{ \sin { \left( \frac { \alpha  }{ 2 }  \right)  }  } ,0 \right)  \\ C & = & \left( r\cos { \alpha  } +t\sin { \alpha  } \tan { \left( \frac { \alpha  }{ 2 }  \right)  } ,0 \right)  \\ { C }' & = & \left( r\cos { \alpha  } +t\sin { \alpha  } \tan { \left( \frac { \alpha  }{ 2 }  \right)  } +\frac { 1 }{ \cos { \left( \frac { \alpha  }{ 2 }  \right)  }  } ,0 \right)  \end{eqnarray}  Attention: $\alpha$ is not the angle of $AOC$, it is some angle $ADC$ where $D$ changes location on $x$ axis for $r\neq t$. I am saying this because images can create confusion. Anyways I will change them as soon as possible.  I could consider $r=f(\alpha)$ and $t=g(\alpha)$ but for this question I am going to take $r$ and $t$ as constants. If they were functions of $\alpha$ there would appear some interesting shapes. I experimented for different functions however the areas are more difficult to calculate, that's why I am not going to share. Maybe in the future.  We rotate the hall for $r=t$ in the example above: In this case:   point A moves on a semicircle  The envelope of lines between A' and C' is a circular arc. One has to prove this but I assume that it is true for $r=t$.   If my second assumption is correct the area of sofa is $A= 2r-\frac { \pi r^{ 2 } }{ 2 } +\frac { \pi  }{ 2 } $. The maximum area is reached when $r = 2/\pi$ and it's value is: $$A = 2/\pi+\pi/2 = 2,207416099$$  which matches with Hammersley's sofa. The shape is also similar or same:    Now I am going to increase $t$ with respect to $r$. For $r=2/\pi$ and $t=0.77$:    Well, this looks like .   I believe thearea can be maximized by finding the equations of envelopes above and below the sofa. Look at  where @Aretino has computed the area below $ABC$.   I don't know enough to find equations for envelopes. I am afraid that I will make mistakes. I considered to calculate area by counting number of pixels in it, but this is not a good idea because for optimizing the area I have to create many images.  I will give a bounty of 200 for whom calculates the maximum area. As I said the most difficult part of the problem is to find equations of envelopes. @Aretino did it.  PLUS: Could following be the longest sofa where $(r,t)=((\sqrt 5+1)/2,1)$ ?   If you want to investigate further or use animation for educational purposes here is the Geogebra file:      Ok, I had some free time and I count number of pixels in the sofa and I am sure that I have something bigger than Hammersley's constant.  First, I made a simulation for Hammersley's sofa where $r=t=2/\pi$ and exported the image to png in 300 dpi (6484x3342 pixels) and using Gimp counted number of pixels which have exactly same value. For Hammersley I got $3039086$ pixels.   For the second case $r=0.59$ and $t=0.66$ and I got $3052780$ pixels. To calculate area for this case:  $$\frac{3052780}{3039086}(2/\pi + \pi/2)=2.217362628$$  which is slightly less than Gerver's constant which is $2.2195$. Here is the sofa:


(Nearly) Width of page table with Multicolumn/Multirow and modified heights

I'm trying to create a header to go across a set of office documents; I tried to use the widetable package with multirow, but that didn't work. Here's the closest I've come so far, using  and the diagbox package:  \documentclass[a4paper,twoside,10pt]{report} \usepackage{diagbox} \usepackage{multirow}  \begin{document}  \begin{table}[] \centering \caption{My caption} \label{my-label} \begin{tabular}{lllll} \hline \multicolumn{1}{|l|}{\multirow{2}{*}{Model Effectivity}} & \multicolumn{4}{c|}{REVISIONS}                                                                                \\ \cline{2-5}  \multicolumn{1}{|l|}{}                                   & \multicolumn{1}{l|}{REV} & \multicolumn{1}{l|}{DESCRIPTION}     & \multicolumn{1}{l|}{DATE}     & \multicolumn{1}{l|}{APPROVED}  \\ \hline \multicolumn{1}{|l|}{\diagbox[dir=NE]{\hspace{35pt} }{ \hspace{35pt}}}                          & \multicolumn{1}{l|}{-}   & \multicolumn{1}{l|}{Initial Release} & \multicolumn{1}{l|}{1/1/2016} & \multicolumn{1}{l|}{Travis} \\ \hline                                                          &                          &                                      &                                \end{tabular} \end{table}   \end{document}   I need to tweak the vbox dimensions on the rows as well - the I had to use diagbox to get the diagonal box I wanted (seems obvious, right?) but it wouldn't go to the corner properly unless I added the hspace elements, which made that box too tall.  How can I get that diagonal slash and a wide table to coexist peacefully (without having to resort to trying to draw it in Tikz)?  Edit: I'm trying to span a much larger percentage of the width of the page than the other questions, I think - however, this is a pretty common type of "header" (not in the LaTeX sense) that is found on engineering documents.   I'm adding a similar image: there's quite a bit of blank space in it (so that later, the description of changes can have a few words about what was changed, or what ECO was incorporated.   [Edit 2] So I tried to force the widths to work out the way I wanted using eqsetminwidth, then used adjustwidth to bring the table back to center (by manually moving it around - which is not elegant at all, but at least it's the right idea!). Now just have to figure out why it has those vertical lines under the first column...   \documentclass[a4paper,twoside,10pt]{report} \usepackage{diagbox} \usepackage{array, multirow, caption} \usepackage{eqparbox} \usepackage{adjustbox} %\usepackage[showframe=true]{geometry} \usepackage{changepage}  \makeatletter \newcommand*{\centerfloat}{%   \parindent \z@   \leftskip \z@ \@plus 1fil \@minus \textwidth   \rightskip\leftskip   \parfillskip \z@skip} \makeatother  \begin{document} %\eqsetminwidth{<tag>}{<width>} \eqsetminwidth{R}{4.5in} \eqsetminwidth{D}{3.5in} %\begin{adjustbox}{center} \begin{table}[!htb] \makeatletter \setlength{\@fptop}{0pt} \makeatother %\centerfloat %\noindent \begin{adjustwidth}{-1.75cm}{}   \centering\renewcommand\arraystretch{1.333} %  \caption{My caption} %  \label{my-label}   \begin{tabular}{|*{5}{c|}}     \hline     \multicolumn{1}{|c|}{\multirow{2}{*}{\eqmakebox[H]{Model Effectivity}}} & \multicolumn{4}{c|}{\eqmakebox[R]{REVISIONS}} \\     \cline{2-5}                                                                                & \multicolumn{1}{l|}{REV} & \eqmakebox[D]{DESCRIPTION} & DATE & APPROVED \\     \hline     \diagbox[dir=NE, width =\dimexpr\eqboxwidth{H} + 2\tabcolsep\relax, height=0.6cm]{}{} & --- & Initial Release & 1/1/2016 & Travis \\     \hline    \end{tabular} \end{adjustwidth}    \end{table} %\end{adjustbox}  \end{document}


Is it possible to emulate a linked list in java by nesting a class within a class? I have tried to implement, but the summation function doesn't move passed the first class. This generates a 1 no matter what integer it is given:  public class Example {     static class Item{        boolean b;        double d;        Item nextItem;        Item (boolean b, double d, Item nextItem) {           this.b = b;           this.d = d;           this.nextItem = nextItem;        }     }      static double f(Item item) {        if(item != null)           return (item.b ? item.d : 0.0) + f(item.nextItem);        else           return 0.0;     }      static public void main(String args[]) {        int n = Integer.parseInt(args[0]);        Item firstItem = null;        firstItem = new Item((1%2!= 0), Math.sqrt(1), null);        if(n > 1){           Item nextItem = firstItem.nextItem;           for (int i = 2; i <= n; i++)  {              nextItem = new Item((i%2!=0), Math.sqrt(i), null);              nextItem = nextItem.nextItem;           }        }        double s = f(firstItem);        System.out.println("sum = " + s);    } }


How to avoid pagenumering with text in scrlttr2


Suggested edits pending approval indicator lights when I exceeded daily review limit

Recently top-bar started to feature indicator with number of pending reviews [actually it seems that it shows number of suggested edits approvals only, not sure]. That's good.  But why does it appear even after I have exceeded daily review limit? It's distracting, especially as it appears/disappears very frequently.  Is it a [kind-of] bug or does it have a purpose that I'm missing?


In what way am I more likely to be DDoS'd? Via http or other ports?

I am writing a web service that has a lot of vicious competitors. Vicious as in: people have been getting DDoS'd within hours of setting up shop in this arena.  The service will consist of:   a website that you can sign up to and check on stats/etc... (all of which is served using https) a web service that runs in the port 8000+ range.   What (if any) port will be easiest to attack and/or bring down the server? The web server or the web service?  I know nginx has some pretty good DDoS protection so I am looking into that and load balancing for the website.  Any suggestions as to dynamic DDoS protection against various other ports with linux would be appreciated.


Black screen after login to Windows Server on GCP

I have a problem when I launch a remote desktop that I created in Google Cloud Platform. I have a black screen and a command line on it. I can’t do anything. What is the problem and what should I do?


How can I give my friend one of my world saves in Terraria?

Me and my friends play Terraria a lot and we only use one main world and I created it. I am not always on as much as they are and they want to use be able to play when i'm not on. Is there a way that I could send  one of my friends the World Save so they could host it instead??


Viewing link to flag summary when you have not yet helpful flags

When someone creates a new account on an SE site, and when he/she flags a post for the first time, he/she can't see whether this flag is still active, or got declined, because the "Helpful flags" link only appears when someone has at least one flag marked as helpful. This could be annoying, because if this flag gets rejected, then he/she can't see why this flag was rejected (if a specific reason is added).  So, my suggestion is: after someone has flagged one post (and if it's not yet marked as helpful), show a "Helpful flags: 0" link, so people can see whether his/her flag is still active or declined.


Firefox style left hand bookmarks menu for chrome

Pressing ctrl + b in firefox opens a bookmarks toolbar, I'd like to move to chrome but this is holding me back.   Is the same functionality available in a chrome addon, searching hasn't yielded any results.


Is it possible to transform an armature into a curve?

I have a tunnel that I want a camera to go through, and want to replace the armature with a curve so it moves exactly on that path. I'd like the camera to also rotate to follow the bends of the tunnel. Using cycles.   Appreciate it, the problem I'm having now is that the camera follows the path, but after each turn, kind of snaps back or bumps, like a recoil of sorts. I reduced the size of the turns, but it still happens. And within the graph editor I can't change the interpolation mode, it's all greyed out. The only reason it looks kind of decent is because the camera is set to 15mm. Any ideas?


Where are some good places to find free illustrations?

Possible Duplicate:          I'm looking for good places to find illustrations (not photos). Any places online with free illustrations that you would recommend? I'm looking for "Caricatures", backgrounds, cartoonish.


grive-tools and google-drive-ocamlfuse are not more working...does someone know another free (better open source) service for google account in ubuntu? Thanks


How does the Twinned Spell metamagic option interact with the Draconic Bloodline sorcerer's Elemental Affinity feature?

The  states:  When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip). To be eligible, a spell must be incapable of targeting more than one creature at the spell’s current level.  The 's 6th-level Elemental Affinity feature (post-) states:  Starting at 6th level, when you cast a spell that deals damage of the type associated with your draconic ancestry, you can add your Charisma modifier to one damage roll of that spell.  It's known that Twinned Spell does not create another spell, it just targets another creature with the same spell. For example, . On the other hand, ; even if it applies to one damage roll, that damage roll is applied to all targets. That said, does Twinned Spell use the same damage roll against the two targets, thus allowing Elemental Affinity to apply to both targets? Or does it use different damage rolls, and thus Elemental Affinity applies only to one target?  The description of  in the rules says  If a spell or other effect deals damage to more than one target at the same time, roll the damage once for all of them. For example, when a Wizard casts Fireball or a Cleric casts Flame Strike, the spell’s damage is rolled once for all creatures caught in the blast.  So, the question can be rephrased as: does Twinned Spell make the spell deal damage to both targets at the same time or not?


Consider the ODE $$\frac{dy}{dx}=x^{2}+y^{2}, y(0)=0.$$ I have to find the interval of unique solution by using Picard method. As in my local book it is solved as $$|f(x,y)|=|x^{2}+y^{2}|\leq a^{2}+b^{2}=M. $$ $$h=\min\{a,\frac{b}{M}\}$$ where $M=a^{2}+b^{2}$. So $h=\min\{a,\frac{b}{a^{2}+b^{2}}\}$. Then my main problem is the author do like $$a=\frac{b}{a^{2}+b^{2}}$$ which gives a quadratic in $b$ as $ab^{2}-b+a^{3}=0$ with discriminant as  $1-4a^{4}=0$ gives $a=\frac{1}{\sqrt{2}}$ so $|h|\leq\frac{1}{\sqrt{2}}.$ Please suggest me how he  find $h=\min\{a,\frac{b}{a^{2}+b^{2}}\}$? Why he put $a=\frac{b}{a^{2}+b^{2}}$? Thanks in advance.


Is it possible to push on Git when I only have a subdirectory of the project on my local repository?

I have a local git repository that is configured to connect remotely over SSH on Gitlab (let's call it git@gitlab.com:myrepo/myproject.git), after cloning repositories I like to keep only a specific folder of the project locally, I do it using the command:  git filter-branch --prune-empty --subdirectory-filter subdirectory HEAD~..   This command makes the local repository keeps track of the subdirectory folder on the remote git project (and overlook all the files that are before this folder on my project). As long as I'm using it only for pulling it's fine... The problem is if I try to push changes to that remote branch, if I try I see the following error:  $ git push -u origin master To git@gitlab.com:myrepo/myproject.git  ! [rejected]        master -> master (fetch first) error: failed to push some refs to 'git@gitlab.com:myrepo/myproject.git' hint: Updates were rejected because the remote contains work that you do hint: not have locally. This is usually caused by another repository pushing hint: to the same ref. You may want to first integrate the remote changes hint: (e.g., 'git pull ...') before pushing again. hint: See the 'Note about fast-forwards' in 'git push --help' for details.   I haven't found anything to this specific case on git push --help. Does anyone know if it's possible to push on a remote folder when I only have a subfolder of the project on my local repository?


How do I prove that $p = x^2 +2y^2 $ iff p $\equiv$ 1 $\mod{8}$ or p $\equiv$ 3 $\mod{8}$?

The title pretty much says it. If $p$ is an odd prime, how do I prove the following?: $p = x^2 +2y^2 $ iff p $\equiv$ 1 $\mod{8}$ or p $\equiv$ 3 $\mod{8}$


Inequality involving the pseudo inverse $A^+$

Say I have a matrix of the form  $$ A =   \begin{bmatrix}    A_1     \\    A_2  \end{bmatrix} $$  where $A_1$ is a $n \times n$ matrix of full rank, and $A_2$ is a $(m-n) \times n$ matrix (arbitrary).  I would like to show that $||A^+||_2\leq||A_1^{-1}||_2$  where $A^{+}$ is the pseudo inverse, defined $(A^*A)^{-1}A^*$. I have said that, $$A^+ = (A_1^{*}A_1 + A_2^{*}A_2 )^{-1}[A_1^* A_2^*]$$  lets look at the first part of this matrix $$(A_1^{*}A_1 + A_2^{*}A_2 )^{-1}A_1^* = [A_1 + A_1^{-*}A_2^*A_2]^{-1}$$ this is as far as I can go with regards to manipulating this matrix as $A_2$ is not square it does not have inverse.  I am a bit unsure how to progress...


Given an SBox, how can I generate its component equations (in ANF)? given in this link:  For example, let's say I have this SBox: $$\{1, a, 4, c ,6 ,f ,3, 9, 2, d, b, 7, 5, 0, 8, e\}$$


Moving conductors in magnetic fields: is there electric field or not?

this is my first question on PhysicsSE (I'm already an user of MathSE).   I'm a mathematics students trying to understand Faraday's law, that is   $$\varepsilon= -\frac{d \Phi_B}{dt}$$  where $\varepsilon$ means electromotive force and   $$\Phi_B=\iint \mathbf{B}\cdot d\mathbf{S}$$   means flux of magnetic field. As my textbook points out, there is an interpretation problem here: if the change in magnetic flux is due to movement of the conductor, then free charges in it are subject to Lorentz force, which then causes a current. On the contrary, if the conductor holds steady in a changing magnetic field, the induced current must be explained in terms of an electric field $\mathbf{E}$, described by the equations   $$\begin{cases} \nabla \cdot \mathbf{E}=\frac{\rho}{\varepsilon_0} \\ \nabla \times \mathbf{E} = - \frac{\partial \mathbf{B}}{\partial t}\end{cases}.$$  Question Do those equations hold if we have a moving conductor in a stationary magnetic field? I guess not: this would mean $\mathbf{E}=\mathbf{0}$. How to solve this?


How to prove that $N\setminus A$ is finite?

$A \subseteq \mathcal{R}(N)$ and given that (by inductive definition):   $N ∈ S$. If $a \in R$, then $R \setminus \{a\} \in A$.    I need to prove that for each $A \in S$, $N\setminus A$ is finite. How can I prove this formally?


So I was thinking... If heat I feel is just lots of particles going wild and transferring their energy to other bodies, why am I not burned by the wind?  When I thought about it more I figured out that wind usually carries some humidity, and since particles of liquid are moving same speed as the wind, they are basically static relative to each other, so no energy is transferred between them (wind and water particles). And if that water sticks to my skin and wind blows, it'll evaporate thus taking energy from my skin and make me feel cold.  Thing is, I don't think that's really the case but even if it is, if I somehow dry out the wind, will it burn me if it's strong enough? And winds can reach some pretty high velocities (though I must admit I'm not sure if they are comparable to movement of atoms in warm bodies etc...).  So. Bottom line. Can I be burned by wind in some perfect scenario?


Are there any instances of a Jedi using the Force on themself?

The Force can be used for moving objects, including living animals.  There are a few instances I can think of where the Force is used on a person, such as Anakin using the Force in Season 1, Episode 4 of The Clone Wars on Padme when she has to jump between trains.  Has there ever been a situation, in TV shows, comics, or the EU, where a Jedi has used the Force on their own body, such as propelling themself up a ledge or almost flying?  I am excluding cases such as jumping higher than normal; I am thinking of more outright examples.


When do I say "I have seen people do it" and not "I have seen people doing it"?

What is the difference between  I have seen people do it and I have seen people doing it?


An expression that adds little information

There is a family of expressions called oxymorons which contain contradicting meanings. What about expressions that add little meaning like "fatally injured" or "the evening sunset"? What are these expressions called?


How do I smooth edges of polygons in QGIS?

Is there a built in function or plugin I can use to achieve smooth lines for my polygons instead of the blocky ones I have now?


I will be travelling to the USA in a month (by plane) but have found one-way flights are more expensive than return. Is there a good way to deal with this? So I can book the cheapest flight possible, when and where might I look to book?


Recover My account whose email address is closed

I have created my account on stackoveflow from my company email address. link :     Now as I have left the company so my email account has been closed. How I can recover my account.


To prove given set is basis for topology on $\mathbb{Z}$

An arithmetic progression in $\mathbb{Z}$ is a set  $A_a,_b=\bigg\{\dots,a-2b,a-b,a,a+b,\dots\bigg\}$ with $a,b\in\mathbb{Z}$ and $b\neq0.$ prove that the collection of arithmetic progressions   $B=\bigg\{A_a,_b|a,b\in\mathbb{Z}\ and\ b\neq0\bigg\}$ is a basis for topology on $\mathbb{Z}$  any hint


What would be better practice when giving a function the original variable to work with:  unsigned long x = 4;  void func1(unsigned long& val) {      val = 5;             } func1(x);   or:  void func2(unsigned long* val) {      *val = 5; } func2(&x);   IOW: Is there any reason to pick one over another?


Is it possible to clear only 301-redirects from Firefox's cache? CTRL+F5 doesn't do the job since you just reload the target without caching but do not clear the cached redirect.  An option to disable caching of those redirects completely would be fine, too - but some way (possibly through an extension) to remove those cached redirects would be better.  Note: I'm not looking for answers that disable all caching (including CSS, JS, etc.)


Amateur photographer unsure what camera to buy; would also like the ability to take high quality videos

I am an amateur photographer and filmmaker, it is now time to buy my own camera. I have had my eye on the Canon 760D but I was wondering if there were more models I could consider without spending so much money. A dSLR is definitely the main option. If I could get some advice on what to look for and what to get, that would be great.


YA coming-of-age fantasy series, protagonist keeps pigs

I lost a series books during a move and I'm thinking I might like to get them for my son.  They are about a teenage orphan who lives with a (sort of) wizard who's primarily known for his prize pig. There is a "bad guy" but he doesn't do much - he starts off the action in one by scaring the pig, and the boy has to chase after it. He goes on several such adventures, notably one to "find his true nature" that ends with him staring into a pool.  I suppose it could be the early books of , but I'm pretty sure I read them in the 1980s, not 90s, and title seems wrong. And unlike the Wiki description, in the series I'm thinking of, there's no real magic to speak of - its "out there" but does not seem to be part of the action that I recall.


I'm trying to write a function that formats every (string) member/variable in an object, for example with a callback function. The variable names are unknown to me, so it must work with objects of all classes.  How can I achieve something similar to array_map or array_walk with objects?


Is there a way to cast Func to Func given I know v1 and v2?

So I have this function that takes a function with no parameters:  public static bool RetryUntilSuccessOrTimeout(Func<bool> task, TimeSpan timeSpan)     {         bool success = false;         int elapsed = 0;         while ((!success) && (elapsed < timeSpan.TotalMilliseconds))         {             Thread.Sleep(1000);             elapsed += 1000;             success = task();         }         return success;     }   And then I have a bunch of functions like:  private static bool OnDeleted(object source, FileSystemEventArgs e){...} private static bool OnChanged(object source, FileSystemEventArgs e){...} private static bool OnCreated(object source, FileSystemEventArgs e){...}   I have a function that takes same aruments as those three. So I have that information provided. Is there a way to pass these function as ones not taking any arguments (because I provide them) so i can pass it into the "task" of RetryUntilSuccessOrTimeout() ?    An encapsulating image of the problem:


what type of hypotheses does "goodness of fit" signifies , i.e is it single tailed or two tailed?

Suppose it is required to test the fitting of binomial distribution to the following data ( at level $\alpha =0.05$) :    the parameter p is estimated as p = 0.494 , and the expected frequencies (given in red ) are also calculated .  let the claculated value of chisquare statistic (using the formula $\sum\frac{(O_i - E_i)^2}{E_i}$ ) be  $\chi_{cal}^2 $ (say)  my question is : what  type of hypotheses does "goodness of fit" signifies , i.e is it single tailed or two tailed ?  in other words ( or expressing my question more clearly by showing the way i attempt it)  $ H_0 : $ $ P = 0.494 $ or fit of the model is good   $ H_1 : $ $ P \ne 0.494$ or fit of the model is not good   then the test criteria should be to  accept $ H_0 $ iff  $\chi_{0.025}^2 \le \chi_{cal}^2  \le \chi_{0.975}^2 $  but thats not the actual story  , every source that i reffered , says that test criteria should be to  accept $ H_0 $ iff  $ \chi_{cal}^2  \le \chi_{0.05}^2 $ , why is this happening , if its a two tailed hypotheses then both ends should be reffered ? please correct me where i am wrong


How do I make a dynamic cli like the top command

I want to make a program that will display dynamic data in the way the "top" command does but, I haven't been able to find out how to make the command line interface work. Does anyone know of some resources for building that type of interface?


Is output buffering enabled by default in Python's interpreter for sys.stdout?  If the answer is positive, what are all the ways to disable it?  Suggestions so far:   Use the -u command line switch Wrap sys.stdout in an object that flushes after every write Set PYTHONUNBUFFERED env var sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)   Is there any other way to set some global flag in sys/sys.stdout programmatically during execution?


While reviewing some slides I see the following formula for calculating lift (which is defined as "measure of dependent/correlated events"):  $$lift(A,B) = \frac{s(A\cup B)}{s(A)\cdot s(B)}$$  which for this table:  \begin{matrix}  & A & \overline{A}\\  B & 400 & 350 \\  \overline{B} & 200 & 50 \end{matrix}  gives the following result: 0.4 / (0.6 * 0.75) = 0.89  and tells that if lift = 1 then events are independent, if < 1 negatively correlated and if > 1 - positively.  I can understand how the calculations are made, but I can not understand the reason behind it and how correlation is connected (wanted to write correlate :-) ) to the number 1.  I have seen a  about lift, but it looks to me like a completely different question.


Underscores in URLs are not correctly handled in comments

I first wrote the following comment.  It is not true that there is just a _White House_: In Moscow, there is a [government building](http://en.wikipedia.org/wiki/White_House,_Moscow) that is called _White House_.   It was not rendered correctly, as it appeared as follows. (See the first comment for this question.)     It is not true that there is just a White House: In Moscow, there is a  that is called _White House.   To make it render correctly, I had to rewrite it as:  It is not true that there is just a _White House_: In Moscow, there is a [government building](http://en.wikipedia.org/wiki/White_House,\_Moscow) that is called _White House_.   In this case, it is rendered correctly also in comments.     It is not true that there is just a White House: In Moscow, there is a  that is called White House.   Looking at the HTML produced for the comments, I understand what happened. In the first comment, the HTML is the following.  It is not true that there is just a White House: In Moscow, there is a government building that is called _White House.   In the second comment, the HTML is the following.  It is not true that there is just a White House: In Moscow, there is a government building that is called White House.   In the first comment, the URL is http://en.wikipedia.org/wiki/White_House,%3Ci%3EMoscow which means the underscore is changed to , and then the brackets are encoded, giving as result the %3Ci%3E part that is visible in the URL.  This happens only in comments. If I write the following Markdown in a post, it is rendered correctly, as visible here.  It is not true that there is just a _White House_: In Moscow, there is a [government building](http://en.wikipedia.org/wiki/White_House,_Moscow) that is called _White House_.      It is not true that there is just a White House: In Moscow, there is a  that is called White House.   The HTML in this case is the following one.
It is not true that there is just a White House: In Moscow, there is a government building that is called White House.


Calculate the Factor Group $(\mathbb{Z}_4 \times \mathbb{Z}_6)/\langle(0,2)\rangle$

I am attempting to understand and compute: $(\mathbb{Z}_4 \times \mathbb{Z}_6)/\langle(0,2)\rangle$   I know $(0,2)$ generates $H = \{(0,0),(0,2),(0,4)\}$, which has  order 3 because there are 3 elements. Now, I must find all the cosets  which there should be 8. The reason there should be 8 is because $4\cdot 6/3 = 8$.  This is where I run into the issue. I have a hard time generating the cosets, but furthermore, once I actually do get the cosets, I have a hard time analyzing them and knowing what it means. If someone could walk me through a step-by-step solution that would be great.  The answer is that the factor group is isomorphic to $\mathbb{Z}_4 \times \mathbb{Z}_2$.   Reference: Fraleigh, A First  Course in Abstract Algebra, p. 147, Example 15.10.


Word for someone who pays attention to details

I know I've seen a word that describes a person who has a high perception of details (for example, seeing specific information in a log file), but I can't recall it now.  Insights?


Since I have an onboard Intel graphics card, and a ATI Radeon display controller, I was wondering if I could switch between the two as my graphics in use, as I could in 14.04 LTS through ATI Catalyst?  16.04 LTS is using the onboard, and the hardware listing lists ATI as well as display controler, but not in use. Additional drivers don't provide anything.   So is AMDGPU being used, or is ATI disabled?  lspci:  00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated Graphics (rev 09) 04:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Venus XTX [Radeon HD 8890M / R9 M275X/M375X] (rev ff)   lspci -nnk | grep VGA -A1  00:02.0 VGA compatible controller [0300]: Intel Corporation Broadwell-U Integrated Graphics [8086:1616] (rev 09)     Subsystem: Lenovo Broadwell-U Integrated Graphics [17aa:3824]


How can I find out what RAM a computer system has?

I'm looking for a way to find out what kind of RAM a system has (clocking speed, DDR-X etc.). Is there a specific command for that? I'm only aware of free or lspci which don't offer those things.


How to remove array by it's value in php?

This is my array and i want to remove array which keyval is 60138. How to remove specific array using it's value ?  Array     (     [name] => Hydrangeas.jpg     [keyval] => 23905     )     Array     (         [name] => Chrysanthemum.jpg         [keyval] => 87936     )     Array     (         [name] => Penguins.jpg         [keyval] => 60138     )     Array     (         [name] => Tulips.jpg         [keyval] => 82902     )   Thanks in advance.


What is considered a matchmade game in LoL?

So recently (or maybe not recently, I just started playing again) Riot implemented a . I'm still really confused how it works, but I managed to obtain another box besides the one that they gave me as intro-freebee. Now I think I need a key, but i don't know how to earn one. The article i posted in that link above says:     Earn keys as rewards for winning any matchmade games or by purchasing them at the store for 125 RP. Keys unlock chests through Hextech Crafting.   But I don't know what a "matchmade" game is officially.  says:     anything that uses the matchmaking system, so custom games are out, and that's it   but that doesn't help because I still don't know what the matchmaking system is. Aren't all games made by matching? if so, why didn't i receive keys for winning a normal-draft game? And I have RP but whats the point of spending it on this if i can just win it somehow?


Creating coordinates from beg and end points on a line

Is it possible to create WGS-1984 coordinates from the start and end points along a line segment?   The line features were created using linear referencing but now I need to create lat and long coordinates for the start and end of each line segment.   Here is some of the data from the attribute table:  OBJECTID *  CORRIDOR_CODE_RB    FRFPOST TRFPOST Shape *    9        C001976N               0      0.76  Polyline M    10       C002068N             0.432    0.984 Polyline M    11       C002111N               0      0.432 Polyline M


access file when I am connected to his wi-fi network

I have an andriod device.Can I access files of another android device ? I am connected to his wi-fi network. if yes how??


Can I download Ubuntu on to a Mac, save it to a memory stick to install on a PC and leave the Mac untouched?


Why regular expression doesn't match input with sed command

I'd like to cut extra spaces from "ps aux" output and replace them with one space. What I do is:  ps axu | sed 's/[ ]+/ /g'   But output seems to be unchanged, I still get too much spaces between tokens.  username    4876 ... <the rest of columns ommitted>   Why this regular expression doesn't match empty space between username and pid?


Can I import animations into other blender files?

I want to know if I can create an animation in a separate Blender file, and put it into another file so I don't have to worry about the scenery in my Animation. Thanks!


Why does signing on to one site not sign me on to all of them?

I've seen this question asked 3 times, but in none of those threads did I find a satisfactory answer.  I'm not asking about reputation: it makes sense that different sites should have different reputations.  However, consider the StackExchange drop-down menu at the top left of the screen.  When looking through the "Hot questions", the links are often to sister websites of StackExchange (programmers.stackexchange i.e.).  It doesn't make sense to me that if I go to one of those sister sites, I'm no longer logged in.  I feel like it's counterintuitive to click a link to go answer a question, only to find that you can't answer that question until you log in.  What is the reason for this?  Is there an option to do as I'm suggesting?


How to disable/remove all badges and reputation?

Is there any setting/userscript/extension available to disable/remove all reputation, badges and badge notifications from the stackoverflow interface?  It just clutters the interface for me and I don't see the point in having them.  Activity on sites like stackoverflow as someone that answers questions should be purely altruistic anyway ;)  In addition to the greasemonkey script mentioned in the answers I'm also using this userscript in Opera  if(/(stackoverflow|superuser|serverfault)\.com$/.test(location.hostname)){     opera.addEventListener('BeforeScript', function(e){         var o = document.getElementById('notify-container')         if(o){             o.style.display = 'none';             removeEventListener.call(opera, 'BeforeScript', arguments.callee, false);         }     }, false); }


Show function $f(x,y)=(x^2-y^2,2xy)$ is $1$-$1$ by Inverse Function Theorem

I'm trying to prove the problem below - which comes from Munkres' "Analysis on Manifolds" book in the section on the Inverse function theorem.  Since its in the chapter on the Inverse Function Theorem I figured I'd start by showing that $f$ satisfies the conditions of the theorem.  Writing the Jacobian shows that it's both $C^r$ and we get $\det f'(x,y)=4x^2+4y^2\neq0$ when $x>0$.  So we can apply the theorem but I'm unsure of how to proceed to show that $f$ is $1$-$1$.  And I didn't see how to use the hint they provided.  Thanks!      Let $f\colon \mathbf R^2\to \mathbf R^2$ be defined by the equation   $$f(x,y)=(x^2-y^2,2xy).$$   (a) Show that $f$ is one-to-one on the set of all $(x,y)$ with $x>0$. [Hint: If $f(x,y)=f(a,b)$, then $\|f(x,y)\|=\|f(a,b)\|$.]


In the definition of 'Compact set', why do we require the existence of finite subcover for any open cover? Why not countable subcover?

For a given topological space, in the definition of 'Compact set', why do we require the existence of finite subcover for any open cover? Why not countable subcover? In particular, what is the importance of having finite subcover for an arbitrary space?   Any help in this regard would be appreciated.


What determines the path where the system searches for a file?

I am trying to get  to work. In the process, I seem to have two versions of it installed: A corrupt one installed in ~/bin, and another I just compiled and ran make install to put it in /usr/local/bin/npm. So, I moved the entire ~/bin folder into ~/old/bin ... but still when I run npm the system searches in ~/bin: $ which npm /usr/local/bin/npm $ alias npm -bash: alias: npm: not found $ npm -bash: /home/ubuntu/bin/npm: No such file or directory $ echo $PATH /home/ubuntu/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games $  What causes Ubuntu to look for npm in ~/bin/npm ? I'm using Ubuntu 11.10. I don't know if the question is ubuntu-specific or not, it can be moved to askubuntu if needed. I do see ~/bin in the PATH, but as far I as understand this only means that if npm was present at ~/bin then it would have used it ... but why does bash insist to look for it specifically there? Why doesn't it find /usr/local/bin/npm, even though the which command does find it?


What short story has a ball chasing a researcher to add him to its collection?

This story had a researcher landing on an uncharted planet to see if it was any good for mining some type of mineral/metal.  Whilst there he encounters this type of ball that chases him all over the planet. He ends up finding this ball’s collection of other things it has caught including animals all the way back to the dinosaurs.  On the ball it has the writing '+/-7.  In the end it chases him for so long that he weighs too little for the balls 'collection'.  Any ideas greatly appreciated.


I have been recently using the system monitor to track my memory usage. When checking I noticed that my Load is showing up as 25 or greater. I noticed the cpu doesn't seem that taxed though so I wonder why the load would be so high. The computer has an AMD A10-7850K 3.7GHz Quad-Core Processor and I'm running Ubuntu 16.04.    I'm mainly wondering if there is something I should check further or what my options are if this is indeed bad like I think it is.  edited:  uptime  20:34:02 up 1 day, 22:12,  8 users,  load average: 4.92, 4.70, 4.7   ps aux | grep kworker | grep -v u | grep -v H | wc -l  13


I'm trying to (more or less) replicate this phonological rewrite rule:    I'm using the package , and what I manage to accomplish is this:  \documentclass{article} \usepackage{phonrule} \begin{document}  \phonc     {\phonfeat{$-$cnt\\ +hi}}     {[$\alpha$grv]}     {\oneof{%         \phonfeat{$-$cnt\\ $\alpha$grv}\phold\\         \phold\phonfeat{$-$cnt\\ $\alpha$vce}%     }}  \end{document}     My main problem here is what appears after the "when" slash:  (1) The package only provides a left curly bracket - how can I add a right one as well?  (2) The two options within the curly brackets are not well aligned. I think comparing the two pictures themselves says it better than what I could do with words.


Sudo Not Working for Node and NPM Install

I have been running into issues with my Ubuntu server (EC2 instance) where I installed NVM (Node Version Manager) under the default ubuntu user that Amazon provides you (Also the recommended installation) and then installed node with npm version via NVM to the following path,   $which node /home/ubuntu/.nvm/versions/node/v6.12.3/bin/node  $which npm /home/ubuntu/.nvm/versions/node/v6.12.3/bin/npm   with $PATH equal to:  PATH=/home/ubuntu/bin:/home/ubuntu/.local/bin:/home/ubuntu/.nvm/versions/node/v6.12.3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin   but when I try to run sudo commands it is not picking up on npm or node and after some research I’m curious if it has to do with either of the following reasons or if it is something I’m not noticing.   Issue specific to Ubuntu where “node” is associated with a different package, so “nodejs” had to be used? nvm, node and npm need to be installed with sudo so path can be accessed by root   sudo errors:  sudo npm install sudo: npm: command not found  sudo node run sudo: node: command not found   Here are additional environment variables that might be helpful:  HOME=/home/ubuntu NVM_DIR=/home/ubuntu/.nvm USER=ubuntu   Error message sent from deployment logs:  [stderr]/usr/bin/env: ‘node’: No such file or directory


For a specific package, can I find out why it is installed?  So, can I see or it's manually installed, or that it is installed as a dependency of another package? Or that it is installed as part of the distro?


I have a database with an calender table that can be filled. Except date, title etc. You can also enter a brief description.  The description is of type: longtext  and Collation: latin1_swedisch_ci  When people use the form on the website (using text with ë, ä, ü etc) it all gets put into the database without a problem.  But when I try to get the data out of the DB to edit or to show, it doesnt show up. This is because of the special chars.  My website uses charset=iso-8859-1.  I tried to convert the column and the webpage to UTF-8 but nothing works. The Data either doesn't show, or breaks where the special is supposed to be.  Anyone has an idea how I can solve this??


Why do galaxies over time become more refined?

Why do galaxies over time become more refined, ordered and defined instead of more random and disordered?


Recover python process after ssh broken pipe

I'm running a python process on an EC2 instance which takes a few hours to complete. During that time I lost my ssh connection because my internet went out and the pipe broke. I've relogged into my machine but can no longer see the output of my process. I believe the process is still running. Is there a way to recover the output of the process so I can keep track of its progress?


Could not exec dpkg! E: Sub-process /usr/bin/dpkg returned an error code (100)

I'm using 12.04. I'm unable to perform any installation or remove because I lost my dpkg at /usr/bin/dpkg.  I tried with following procedure:  mkdir /tmp/dpkg cd /tmp/dpkg wget http://archive.ubuntu.com/ubuntu/pool/main/d/dpkg/dpkg_1.15.5.6ubuntu4_i386.deb ar x dpkg*.deb data.tar.gz tar xfvz data.tar.gz ./usr/bin/dpkg sudo cp ./usr/bin/dpkg /usr/bin/ sudo apt-get update   But I got an error after running that wget command:  tar xfvz data.tar.gz ./usr/bin/dpkg  tar (child): data.tar.gz: Cannot open: No such file or directory tar (child): Error is not recoverable: exiting now tar: Child returned status 2 tar: Error is not recoverable: exiting now   How can this be fixed?


What do you call a person who craves danger? Like how a person who believes that the pursuit of pleasure is the most important thing in life is known as a hedonist.


How to add a texture to the emitter surface of a hair particle object (over riding object material)

I'm trying to make carpet with a pattern. I applied an image texture to a particle emitter and it looks okay.  However I want the carpet strands to be more realistic so I made an object to emit instead..  But now I'm at a loss as to how to apply the pattern texture to the whole carpet again because the strands now take their material from the single object.


How to get rid of empty blocks on the dashboard?

I created a View called Recent comments and added a block to my dashboard. Afterwards, I deleted the View, which results in an empty block on my dashboard    and the following error message:     Notice: Undefined index: recent-comments-block in   dashboard_page_build() (line 192 of   C:\wamp\www\mysite\modules\dashboard\dashboard.module).   I tried to drag the empty block away after clicking Customize dashboard, but every time I hit Done, it is displayed again. Clearing caches did not help either.  What should I do to get rid of the empty block?


What PDF viewers are available for Ubuntu?

Every second e-mail I get suggests to download Adobe Acrobat reader, but .  Which PDF Viewer are there available for Ubuntu? I’m fine with partial solutions, a perfect match however would not only display PDF files, but also be able to:   stageless zoom (not just predefined steps)  open files in tabs display comments added with other PDF software add and save comments display forms filled in with other PDF software fill in and save PDF forms create and save bookmarks have a presentation mode


What is the rule-of-thumb relation between megapixels and printout size?  If I have a camera with that number of MP I will be approximately be able to print solid xx by yy inch (or cm) photos?


How to make the tick thickness as the axis line?

I am trying to make the thickness of the ticks equal to the axis line thickness. That is what I have so far:  \documentclass{article}   \usepackage{pgfplots}  \pgfplotsset{compat=1.5}   \begin{document}     \begin{tikzpicture}     \begin{axis}[         xlabel=Binding Energy (eV),         ylabel=Intensity (a.\,u.),         xtick pos=left,         x dir= reverse,         ytick = \empty,         every x tick/.style={color=black, thin},         tick align=outside,         xlabel near ticks,         ylabel near ticks,         xmin = 96,         xmax = 108     ]         %\addplot[mark=none] table[x=BE,y=cnts] {si2p.txt};         % This data looks similar:         \addplot[mark=none, smooth] table[x=BE,y=cnts] {             BE      cnts             95      1             98      1             99      10             99.5    5             100 6             101 2             108 2         };      \end{axis}     \end{tikzpicture} \end{document}     But if you take a closer look on the ticks on the outside, you'll see that they are somehow clipped or a least thinner. They are also black so the style seems to work for them.    Is this a bug or can I change the clipping region? And as a second question: is thin the correct value for the thickness?


Short story - Man invents easy to make doomsday device capable of cutting the Earth in half

I'm looking for a story I read in the 90s (probably written much earlier) about a man who is part of some sort of scientific group that discovers a way to build a doomsday weapon capable of cutting the planet in half. All it requires is a coil of wire and some commonly available chemicals.  The man discusses the matter with his wife, and they decide that      no one can be trusted with such dangerous information, so at their next meeting he murders everyone in the group by leaving a drop of acid to slowly burn into a cylinder full of nerve gas.   In the end,      his wife poisons him because she believes that not even her husband can be trusted not to someday use his knowledge to destroy the Earth.


Can I somehow control a PSU-powered fan using a 4-pin fan output on the motherboard?

I have a  that I want to power using an  and control via one of the 4-pin fan terminals on an .    Not considering the wattage of the fan, I originally plugged it into a (known working) fan terminal but it of course would not turn (and the BIOS correctly reported the RPM as 0).  Connecting it directly to the PSU is simple enough, but this would result in it turning at full speed at all times.    I am curious if there is a "DIY" way that I can supply the fan with power from the PSU and control how much actually reaches the fan using the output of the motherboard (using something like an optoisolator to keep the motherboard safe).    The motherboard is able to control 4-wire fans using PWM, and 3-wire fans using DC voltage level.  Is there a product or combination of parts that will do this?  I originally asked this on Super User, but it was deemed more appropriate here due to the involvement of DIY electronics.  Thanks in advance!  EDIT: The 4-pin connectors on the motherboard are indeed keyed to force correct connection of 3-pin plugs.  The BIOS includes a Fan interface that allows you to plot desired RPM vs temperature.  Each fan output can individually be set to either PWM or DC voltage level control.  The motherboard auto-detects what is plugged in (4 or 3 wire) and selects the appropriate setting, but it can be changed manually if desired.  The fan was not purchased through DigiKey, and came terminated with a keyed 3-hole connector (F). It also shipped with a 2-wire (but 4-wide) molex connector (M), unterminated on the opposite end.


I was just wondering what the bests way to include variables in printed-lines.  For example would it be better to do:  print("The cost will be $" + str(cost) + ".")   or  print("The cost will be ${}.".format(cost))   Thanks,  David  P.S. when explaining, note that I am new at programming in general, thanks :D


How I can return from function to main function 3 variable (c++). In the code need be function with take a,b,c value [funk()] and then returning to the main and then those values taking into function [rezult()] My code: #include <iostream> #include <cmath> using namespace std; int funk(); float rezult(float a, float b, float c){     //ax^2+bx-c=0     float D, x1, x2, help;     /*     D=b^2-4ac     x1 = ((-1) * b - sqrt(D)) / 2 * a     */     D = b * b - 4 * a * c;     if (D > 0){         help = (-1) * b - sqrt(D);         x1 = help / (2 * a);         help = (-1) * b + sqrt(D);         x2 = help / (2 * a);         cout << "x1 = " << x1 << endl;         cout << "x2 = " << x2 << endl;     }else if (D == 0){         x1 = ((-1) * b) / (2 * a);         cout << "x1,2 = " << x1 << endl;     }else{         cout << "x1,2 = n" << endl;     } }  int main() {     float a = 0.00, b = 0.00, c = 0.00; funk(); cout << a << b << c<< endl; rezult(a, b, c); return 0; } funk(){     float a, b, c;     cout << "a: ";     cin >> a;     cout << "b: ";     cin >> b;     cout << "c: ";     cin >> c;     return a, b, c; }  But in function funk(); code don't retuning a,b,c values. Where is mistake? a,b,c need be float type


Bounty limit still 100 after deleting answer

states that if you have answered a question and start a bounty on that question, the minimum bounty is set to 100.  I , answered it, deleted my answer (because the solution didn't work) and the bounty limit is still 100.  Is this still by design or is this a bug?  If it is by design, then what is the motivation of this? I understand not wanting to  but applying this to deleted questions seems to not fit with that.


Explain "Please wait while Windows configures..."?

I have installed a plug-in to a program on Windows 7.  However when I start the program I get a progress window saying "Please wait while Windows configures Plugin".  What is going on here? It seems that Windows Installer is running. However I would think that it would finish the installation when I installed the plugin.  I am trying to understand what is going on behind the scenes here. Does Windows ask the Windows Installer every time any program is started if the Windows Installer has an unfinished installation relating to the program or is it something in the program that makes this happen?   I stopped the Windows Installer but this did not help. Some process started it again. How can I find which process this was?  Finally, I deactivated Windows Installer and this "worked".


I am having trouble providing a proof by contrapositive here, can anyone provide a proper proof by contrapositive here?  Let $x \in \mathbb{Z}$. Prove that $3x+1$ is even if and only if $5x-2$ is odd.


Let $f(n) = \sum_{(k,n)=1} e^\frac{2\pi ik}{n}$. Show that $f(n) = \sum_{k=1}^{n}\left(\sum_{d\mid (k,n)} \mu(d)e^{\frac{2\pi ik}{n}} \right) $

I saw a proof for the above that went \begin{align*} f(n) &= \sum_{k=1}^{n}\left(\sum_{d\mid (k,n)} \mu(d)e^{\frac{2\pi ik}{n}} \right)\\  &= \sum_{d\mid n} \left( \mu(d) \sum_{k=0}^{(n/d)-1} e^{\frac{2\pi idk}{n}} \right), \end{align*} in which case for $g(n)=\sum_{k=0}^{n-1} e^{\frac{2\pi ik}{n}}$ we have \begin{equation*} f(n)=\sum_{d\mid n} \mu(d) g(n/d) \implies g(n) = \sum_{d\mid n} f(d), \end{equation*} which then proves the statement above by Mobius Inversion once more, since $g$ is $0$ for all $n>1$.   I understand most of the proof; I'm just not sure how we went through the first two steps of transforming $f(n)$ to get to the point where we can apply the inversion. If anyone can explain the first two steps for me I would appreciate it, thanks!


Find all integer for triplets$(a,b,c)$ [detail]

Find all integer   for  triplets$(a,b,c)$  that  $a+b+c =3$    $a+b^2+c^2=17$  and $a^2 +b^3+c^3 =21$  I have try to start with   $17-a =   ( 3-a   )^{2} - 2bc  \ \ $ and  $21-a^2 =   (3-a)\left ((17-a) -  bc  \right ) +3abc$  but It seems to not be working for me. Could you please guide me any brilliant solution for this problem? Thank you very much.


Google Chrome opens in a new window in a new launcher icon

When I open Google Chrome on Ubuntu 14.04, it opens a new window on a different launcher icon (I have Chrome in my Launcher pinned) and the title of the window is a tab that I don't have open any more. I have uninstalled and reinstalled Google Chrome.


Since I've become active on the Smoke Detector Project, I accumulated over 85 accounts on various stack exchange sites, and all but three are there mainly to flag spam.   I've recently been searching for a way to view a summary of my network-wide flags, with things like helpful/declined and status, like a per-site flag summary.  Does this already exist (if so where can I find it)?  Or could SE maybe provide something like that?  Or maybe could even an userscript provide something like that?


Total work done by friction on a system, when friction is static and internal to system?

Will the total work done by friction on a system be always zero if friction is static and internal to the system? Explain if possible by man boat problem as system and no friction is being provided by water to boat.  Friction only exists between man and boat and man is walking without skidding to the other end.


Novel(s) about a young women that survives an apocalypse and turns into a dragon?

I have vague memories about a novel or series of novels I borrowed from the library as a teenager (1990s). The protagonist was a young woman (pretty sure) who was exceptional. Civilization basically ended (nuclear war maybe). One significant trial she went through involved controlling an orbiting shuttle, trying to dock with a space station (maybe an orbiting Russian weapon?). Then somehow she transferred to a fantasy setting and became a dragon?  Update: A few more details I remember: The story starts out in the USA of the present (meaning the late 80s or early 90s, probably). The protagonist somehow receives early warning or is sheltered from the early parts of the apocalypse (nuclear or biological warfare I think) and goes to space to try to prevent further destruction.


I'm a newbie in LaTeX, I installed MikTeX 2.9 and WinEdt 5.5 . I have this code:  \documentclass[french,a4paper,12pt]{report} \usepackage{babel} \usepackage{graphicx} \usepackage{amsmath,amsfonts,amstext,amssymb} \usepackage{times} \usepackage{setspace} \usepackage{Lettrine} \usepackage{fancyhdr} \usepackage{multirow} \usepackage{pslatex} \usepackage[T1]{fontenc} \usepackage[latin1]{inputenc} \usepackage{array} \usepackage{enumerate} \usepackage{color} \usepackage{version} \usepackage{newcent} \usepackage{nestochp} \usepackage{anysize} \begin{document} \linespread{1.5} \include{page_de_garde} \end {document}    I got this error:    The nestochp.sty isn't found,   What is the reason of this problem? How can i fix it?


Is there a word spelled with a silent B at the start?

My dad and I were playing a game in the car where we picked a letter and then each alternated saying a word that started with that letter. We did it with b, for example, it might go:     Dad: bath   me: ball   dad: buffalo   me: bank   etc.   As we were playing/debating the rules of our game, I noticed that there were no b-words that I could think of that started with a sound other than /b/. Whereas, for example, for words starting with the letter t, some of them begin with the sound /ð/ or /θ/ rather than /t/.  Am I missing some obvious contradictions to this 'rule'? Is there any sort of etymological explanation for this?  To clarify as requested by a comment:  I am looking for   A word that starts with a b that makes a sound other than /b/. More broadly, whether or not there is an etymologically explained pattern among starting letters that shows whether or not there exists the non-phonetic sound at the beginning of a word for a certain letter (or the commonality of the existence of those cases).   From here I'm looking at which starting letters of words have a tendency to be pronounced non-phonetically.


Story about person assigned by test to be a miner when he wants to be an artist

Asking for a friend who is looking for a short story, but cannot remember the title. The friend thinks it is by Le Guin, but the anthologies she had didn’t contain it. "The story is about a land where people are given some kind of an aptitude test by the government and careers planned for them based on the test results. The main character had always wanted to be an artist, but the test says that he has to be a miner. He rails and rants and appeals, but to no avail. So he ends up in this mining place and just hates it. He keeps appealing, but all this requests are turned down. So he slowly adjusts to the place, its roughness and brutality – and makes a life. "One day he discovers some strange minerals in the mines, and takes it home to play with. Over time he creates a whole array of artistic creations that others come to like. And so his life goes on. And then one day there is an urgent missive from the ministry/government that they had screwed up – and that his tests had indeed showed that he needed to be an artist. This never happens they said, but we will make it right. "So he is shipped off to this artists paradise. And once there he realizes he hates these people – they are too airy-fairy and just live in their own heads, and that he wants to go back to his life as a miner and that over time he had come to like its roughness and the space he had built within it."


iPad not reacting to screen orientation - screen lock

How do I correct the "screen lock" on my iPad?  I used to be able to turn the unit a quarter turn and the screen would adjust to my movement. Now it is somehow "Locked".  How can this be fixed?


I have a class DynamicDataDemo, which has a null pointer catch. However I don't understand why jPanel is being passed as null. It is initialized by netbeans as a border layout and size is also declared.     public DynamicDataDemo(final String title){ this(title,null); }      public DynamicDataDemo(final String title, JPanel panel){ super(title); setContentPane(initContents(panel)); }  public JPanel initContents(JPanel contentPanel){     if (contentPanel == null){         System.out.print("You are Here");         contentPanel = new JPanel(new BorderLayout());     }       this.series = new TimeSeries("Data", Millisecond.class);     final TimeSeriesCollection dataset = new TimeSeriesCollection(this.series);     final JFreeChart chart = createChart(dataset);      final ChartPanel chartPanel = new ChartPanel(chart);     contentPanel.setLayout(new BorderLayout());     contentPanel.removeAll();     contentPanel.add(chartPanel, BorderLayout.CENTER);     contentPanel.validate();     return contentPanel;                }   In my main class I call  Final DynamicDataDemo dynamicPlot = new DynamicDataDemo("nameOfPlot", jPanel1);   Any suggestions or solutions greatly appreciated!  Following code was generated by netBeans:  private void initComponents() {      jPanel1 = new javax.swing.JPanel();     jPanel2 = new javax.swing.JPanel();      jPanel1.setBackground(new java.awt.Color(0, 0, 0));     jPanel1.setLayout(new java.awt.BorderLayout());      jPanel2.setBackground(new java.awt.Color(0, 0, 0));     jPanel2.setLayout(new java.awt.BorderLayout()); }  private javax.swing.JPanel jPanel1; private javax.swing.JPanel jPanel2; // End of variables declaration                      Code I wrote:   final DynamicDataDemo dynamicEyePlot = new DynamicDataDemo("Eye Height", jPanel1); final DynamicDataDemo dynamicGainPlot = new DynamicDataDemo("Gain",jPanel2);


How do i find and boot from windows boot manager in Grub 2 after deleting Ubuntu partition

Question: Is it possible to find, locate, or install the windows 10 boot manager through the grub 2 command line? If so, what are those commands? I cannot boot into windows of course and i can not enter ubuntu either. If the questions above are not possible, what are my options? I only want/need windows. Situation: I have a dual boot (windows 10 & Ubuntu) installation on my laptop HDD, and no longer wanted to keep ubuntu on my hdd. I wanted to erase all trace of ubuntu so that i could safely transfer data to an ssd. So Naturally, as someone new to linux, i thought it made sense to simply delete the linux partition from Windows’ Disk Manager since windows was (pre)installed first. Then migrate the data over to the clean ssd. Problem: After deleting the linux partition and extending the c drive to take over unallocated space, I can no longer boot windows. As soon as i turn on my laptop, the GNU GRUB ver 2.04 shows up. In the command line it displays: “grub> ” (It is Not grub rescue) Typing “exit” simply brings me back to the same screen. The UEFI menu that i have doesnt have any option change the boot back to windows bootmgr. I dont have a windows installation disk, or any external windows backup device that was recommended. And I dont currently have but could make another ubuntu live usb, if necessary. But it would be cool if i could do this in grub Neither the hdd nor the ssd can boot windows nor ubuntu. But both devices bring up the GRUB> command line. I now know that data migration moves everything except the boot manager itself. Ive also learned that installing ubuntu gave the booting reigns to ubuntu and took that control away from windows. Which is why uninstalling ubuntu from windows caused this issue.. So my question is, since ubuntu is gone, is windows boot manager also erased? Or is it possible to locate it through GRUB?


Windows 10 Audio input to programs broken

Recently my audio input, from USB headset and USB guitar cable have stopped working. Going into Windows 'Sounds' and enabling 'Listen to this device' outputs the audio as expected; the problem is not with the devices. However, as soon as I try to use them with any other program, discord, for example, no audio input is detected by discord.  I have tried everything I can think of and some suggestions from Googling around;   Updating everything - windows, drivers, all related software Rolling windows back to the last build Trying different USB ports Reinstalling drivers and software Running Windows troubleshooters Playing with device properties settings   But nothing seems to work, any suggestions?


Comparing two groups with different size on multiple continuous variables

I want to compare two groups on 9 continuous variables to see whether mean scores on these variables differ between the two groups. However, my samples have a very different size: one group includes 299 participants, the other group 45.  I performed a MANOVA with the continuous variables as 'dependents' and group membership as 'fixed factor'. I wonder whether I should control for multiple testing in this case? And if so, what is the best way to do this using spss?  Also, the two groups differ on a number of demographic characteristics (all categorical: gender, age, education level), it seems to me that I should check whether the difference I find between the two groups on the continuous variables is not influenced by the difference between the groups in demographic characteristics. But can I do this using MANOVA or would it then be better to perform a regression analysis, and to include the relevant demographic characteristics in a second block?


For my own DNS server, "dig ... @ip-address" works, but "dig ... @domainname" does not

I've recently begun virtualizing servers - one of which is a DNS server running BIND 9 on Debian 7.  My DHCP server correctly issues it as the primary DNS for the network, but I get the following error if I try to use dig kilraine.lan @dns.kilraine.lan  couldn't get address for 'dns.kilraine.lan': not found   Though I get the original dig output from dig kilraine.lan @192.168.1.2.  Details:  BIND 9 on Debian 7; Virtualized CT through Proxmox.  Zone file (the email has been changed to hide my personal info)  ; BIND data file for kilraine zone ; $TTL    604800 @       IN      SOA     kilraine.lan. myaddress.myemail.com. (                      2014060303         ; Serial                          604800         ; Refresh                           86400         ; Retry                         2419200         ; Expire                          604800 )       ; Negative Cache TTL          IN      A       192.168.1.2 ; @       IN      NS      dns.kilraine.lan @       IN      A       192.168.1.2  dns2    IN      A       192.168.1.1 dns     IN      A       192.168.1.2 dhcp    IN      A       192.168.1.3 main    IN     A      192.168.1.10   Reverse zone file  ; ; BIND reverse data file for kilraine.lan ; $TTL    604800 @       IN      SOA     kilraine.lan. myaddress.myemail.com. (                      3006201401         ; Serial                          604800         ; Refresh                           86400         ; Retry                         2419200         ; Expire                          604800 )       ; Negative Cache TTL ; @       IN      NS      dns. 1       IN      PTR     dns2.kilraine.lan 2       IN      PTR     dns.kilraine.lan 3       IN      PTR     dhcp.kilraine.lan 10      IN      PTR     main.kilraine.lan   And lastly my named.conf.local file.    // // Do any local configuration here //  // Consider adding the 1918 zones here, if they are not used in your // organization // include "/etc/bind/zones.rfc1918";  zone "kilraine.lan" {         type master;         file "/etc/bind/db.kilraine.lan"; };  zone "1.168.192.in-addr.arpa" {         type master;         file "/etc/bind/db.192"; };   I have restarted BIND 9 numerous times, and I have always gotten "OK".  I used the dnsutils tool 'dig' on both the server and a client, each return the following      ; <<>> DiG 9.8.4-rpz2+rl005.12-P1 <<>> kilraine.lan ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 46467 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0  ;; QUESTION SECTION: ;kilraine.lan.          IN  A  ;; Query time: 2 msec ;; SERVER: 192.168.1.2#53(192.168.1.2) ;; WHEN: Mon Jun 30 21:53:41 2014 ;; MSG SIZE  rcvd: 30


Explaining risks when seeking DNA testing by cousin?

It has recently occurred to me that I have been in intermittent contact with a second cousin who shares my father Y-DNA (subject to any mutations in the last two generations, which should be slight).  I don't believe he has ever had or considered Y-DNA, and I would like to pay for a test for him, as I have no other identified direct male descendants of my father's male line. My father, his siblings, their father and their father are all deceased and I can't identify any other candidate.  What should I say when broaching the subject to him to reassure him about his privacy/keeping control of the results and persuade him to test?   This is similar to  but the difference from that question is that I would particularly like to describe to him clearly and simply what the real risks of DNA testing are, and why some perceived risks are not risks at all. Some of these risks might be privacy risks; others might be risks from what he learns.


I have to take a website down for a month, which is the least intrusive way to keep achieved SEO optimizations?  should I just add in apache config:  <Directory /root-directory-of-web-site-to-be-redirected>     Redirect 301 /  http://www.otherdomain.com/temporarily_offline.html </Directory>   ....  Reason for the long downtime: some misconfiguration in ruby, while all other php sites work fine. I will fix this after a month when I am back from hollidays


how to make a box over my title? Just a box (like that one on the picture) on my titlepage?  kind regards


I am interested in describing the group of special orthogonal matrices $SO(n)$ by a set of parameters, in any dimension. I would also like to obtain an expression of the density of the Haar measure in this set of parameters. Could anyone help me on this or indicate a good reference? Thanks


Creating Map Book with face to face pages showing before and after digitizations?

I want to create a mapbook that displays changes in river flows over time. I have one shapefile of my recent digitizations, as well as ones done prior. I was hoping to display them, new on the left and old on the right.   Does anyone know if this is possible?  I'm using ArcGIS 10.1 for Desktop.


"Software" and "OS Updates"available in Ubuntu Software

I'm using Ubuntu 16.04.3 LTS, on a 64-bit system.   There are two available updates in "Updates" section of the Ubuntu Software, named OS Updates and Software respectively:      I usually update through Software Updater utility, (and occasionally used sudo apt update and sudo apt upgrade as recommended by some software installation tutorials)- anything that I think is required. So why is Ubuntu Software showing these updates? Should I install them?  As far as I know, these types of updates, if you look at the list, aren't ever available in the Software Updater.


How can I position an image in an arbitrary position in beamer?

I am making a presentation using beamer, and I want to be able to position a certain image the way I want in a frame. I am not sure how to do that. Is there some way you can specify coordinates in the frame and then set an image there?  Is there a better way to place images in various places with the beamer class?