I got as far as   $$|z-2i|=3|z+3| \Leftrightarrow \\  (\ldots) \Leftrightarrow \\ x^2-y^2+4y-4=9x^2+54x+81-9y^2 \Leftrightarrow \\ x^2-9x^2-y^2+9y^2+4y-4-54x-81=0\Leftrightarrow \\ -8x^2+8y^2+4y-85-54x=0 \Leftrightarrow \\ 8y^2+4y-8x^2-54x-85=0\Leftrightarrow \\ y^2+\frac{1}{2}y-x^2-\frac{27}{4}x=\frac{85}{8}$$  Then I tried to complete the square:  $$y^2+\frac{1}{2}y = 0\Leftrightarrow (y+\frac{1}{4})^2-\frac{1}{16}$$  $$-x^2-\frac{27}{4}x=0 \Leftrightarrow -(x+\frac{27}{8})^2+\frac{729}{64} = 0 \Leftrightarrow (x+\frac{27}{8})^2-\frac{729}{64} = 0$$  And so the equation becomes:  $$(y+\frac{1}{4})^2-\frac{1}{16}+(x+\frac{27}{8})^2-\frac{729}{64}=\frac{85}{8} \Leftrightarrow \\ (y+\frac{1}{4})^2+(x+\frac{27}{8})^2=\frac{85}{8}+\frac{1}{16}+\frac{729}{64} $$  According to my book the center is $-\frac{27}{8}-\frac{1}{4}i$ which I got right but the radius is $\frac{\sqrt{117}}{8}$.  What went wrong?


I need help recovering my old accounts and I have a bunch to find and I've tried looking up by phone number and it didn't work


The closure of $c_{00}$ is $c_{0}$ in $\ell^\infty$

let $x=(x(1),x(2),\ldots,x(n),\ldots)\in c_0$  So for any $\varepsilon>0$ there exists a $n_0\in\mathbb{N}$ such that $|x(n)|<\varepsilon_2$ for all $n\geq n_0$.  Now for all $n\geq n_0$ ,$||x_n−x||_\infty=\sup{|x(m)|}_{m\geq n_0}\leq \varepsilon_2<\varepsilon$  i have a doubt that regarding the last line. What makes it possible?


A question about a limit involving nested radicals

$$\lim\limits_{n\rightarrow \infty}1＋\sqrt{2+\sqrt[3]{3＋…\sqrt[n]{n}}}$$  Any hint will be appreciated


If $a+b\equiv0\pmod m$ and $c+d\equiv 0\pmod m$ then $ac\equiv bd\pmod m$. Demonstration.

If $a+b\equiv0\pmod m$ and $c+d\equiv 0\pmod m$ then $ac\equiv bd\pmod m$ How to show?$$$$ I tried $$a+b\equiv0\pmod m\Longrightarrow m\mid a+b\\c+d\equiv0\pmod m\Longrightarrow m\mid c+d\\a+b=mk\;\;\text{and}\;\;c+d=mj\\(a+b)(c+d)=m(mjk)\\m\mid ab+ad+bc+bd$$ But from here could solve anything.


Creating a Conversation Between Two Users

So I'm getting an error with my code and I can't find where it's at, and after so long I'm reaching out. I'm trying to create a conversation between two users which I have created before, all fine on this part. The problem is when I'm going to create a new conversation, I'm getting a NullPointerException. I think the code is right and I have tried to do it in other ways, but I am always getting the same error and it doesn't create the conversation I want to create the conversation between the two and then retrieve it or retrieve every conversation that one user has with other  The error is the following:  Exception in thread "main" java.lang.NullPointerException  The lines are marked in the code.  Main Class  private static void INC(Scanner in, Chat ch){      int iduser1=0;     int iduser2=0;     int transvalue=0;       System.out.print("Insert ID User 1:");      iduser1=in.nextInt();      if(iduser1==ch.getUserNameID(iduser1)){         System.out.print("Found" + ch.getUserName(iduser1));     }     in.nextLine();      System.out.print("Insert ID User 2:");     iduser2=in.nextInt();      if(iduser2==ch.getUserNameID(iduser2)){         System.out.print("Found"+ch.getUserName(iduser2));     }     in.nextLine();       do{             System.out.print("Factor de Translacao:");         transvalue=in.nextInt();         in.nextLine();         if (transvalue<1 || transvalue>26){             System.out.println("Factor between 0 and 26");         }      }while(transvalue<1 || transvalue>26);      if(!ch.hasConversation(iduser1)){ /*------------------------Here*/          ch.addConversation(iduser1,iduser2,transvalue);          System.out.println("Sucess " +ch.getConversation(iduser1)+ " e " +ch.getConversation(iduser2));      }else{         System.out.println("Conversation" +ch.getConversation(iduser1)+ " e " + ch.getConversation(iduser2)+ "Already exists");     }  }   Conversation  public class Conversation {      private int ids1=0;     private int ids2=0;     private int transvalue=0;      public Conversation(int iduser1, int iduser2, int transvalue){         this.ids1=iduser1;         this.ids2=iduser2;         this.transvalue=transvalue;     }      public int getIds1() {         return ids1;     }      public void setIds1(int ids1) {         this.ids1 = ids1;     }      public int getIds2() {         return ids2;     }      public void setIds2(int ids2) {         this.ids2 = ids2;     }      public int getTransvalue() {         return transvalue;     }      public void setTransvalue(int transvalue) {         this.transvalue = transvalue;     }  }   Chat  public Chat(){     counter = 0;     current=-1;     users = new Users[MaxUsers];      conversation = new Conversation[MaxConversation];      }  public void addConversation(int iduser1, int iduser2, int transvalue){     if(counter == conversation.length)         resizeConversation();     conversation[counter++] = new Conversation(iduser1,iduser2,transvalue); }  public int getConversation(int iduser1){     return conversation[searchIndexConversation(iduser1)].getIds1() ; }  public boolean hasConversation(int iduser1){     return ((searchIndexConversation(iduser1) >= 0 )); /*------------------------Here*/ }  private int searchIndexConversation(int iduser1){     int i = 0;     int result= -1;     boolean found1= false;     while((i< counter) && (!found1))         if(conversation[i].getIds1()==iduser1)  /*------------------------Here*/             found1 = true;         else i++;      if(found1) result = i;         return result; }


How can I enable permissions to edit Email Deliverability access level? Currently it is not editable and in system mode. I need to edit it and set it to "All Email so I can test Approval and workflow functionality. is it restricted to our organization?


It is said that we should always use std::unique_ptr instead of std::auto_ptr and it is said that we were not able to store a auto_ptr in a container But consider this example:  int main(int argc, char* argv[]){      std::vector< std::auto_ptr<int> > v;     std::auto_ptr<int> u(new int(5));     v.push_back(u);     v.push_back(std::auto_ptr<int>(new int(10)));      typedef std::vector< std::auto_ptr<int> >::iterator v_ap_it;     for(v_ap_it beg = v.begin(), e = v.end(); beg != e; ++beg)         std::cout << **beg << " ";        std::cout << std::endl;     return 0; }   The program runs fine. I've tested it on vC++ 6.0 and it works fine but doesn't run on C++11 and C++14 ! So how could it be not possible to store it in a container?  * does this mean VC++ 6.0 is erroneous? I think so because it a buggy IDE.


Find all positive integers $x$ and $y$ for which $\frac{1}{x} + \frac{1}{y} = \frac{1}{p}.$

Let $p$ be a prime number. Find all positive integers $x$ and $y$ for which $$\dfrac{1}{x} + \dfrac{1}{y} = \dfrac{1}{p}.$$  Multiplying the given expression by $xy$ results in $y+x = \dfrac{xy}{p} \Rightarrow p(x+y) = xy$. I was suggested to get this to the form $(x-p)(y-p) = p^2$, which seems a bit weird to me since I usually with these kinds of questions I would find a system which would lead to finding the correct $(x, y)$, but having the term $p^2$ is not something I've seen before. Is the idea behind this so that I would want to have an expression where I have something of the form $(x-k)(y-n) = p$ and could deduce from here that either $(x-k) = 1$, $(y-n) = p$ or the other way around since $p$ can only have the factors $1$ and $p$?


Short story ID: Bouncing-Ball Time Travel

A little help please. The story I'm looking for is probably late-50's to mid-60's, and may well have occurred in an SF magazine.  A professor is demonstrating his new time machine to a scientific audience. The machine looks like two large spheres touching each other. In operation, one is sent back into deep time (let's say, although my memory has dropped this particular datum, 10 billion years). It will then return to the present, then bounce off its twin and jump back half that temporal distance (5 billion years), return, bounce half again (2.5 billion years), etc. Each trip will take half the time (in present-day units) as the previous, so the whole thing will be over in a finite time.  Before anyone can stop him, he activates it. He begins lecturing the audience, asserting that whatever has happened has always happened. At decreasing intervals the sphere reappears and bounces with a resonant "Boing!". At each jump, the narrative establishes that the appearance of the sphere did change history, and these changes are reflected in the professor's speech.  So it becomes something like "(Boing!) And those who say that this is dangerous might as well be claiming that the day is not 26 hours long (Boing!) or that there are three moons, not seven (Boing!)", etc. And when the final (Boi-Bo-B-B-Boing!) fades away he raises his tentacles in triumph and cries, "See? Nothing has changed!"


when i update and upgrade , i show these lines  The following packages have been kept back:    mysql-utilities   0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.  but when i use dist-upgrade then i show these lines   sudo apt-get dist-upgrade [sudo] password for anki:  Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   sudo apt-get upgrade [sudo] password for anki:  Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following packages have been kept back:   mysql-utilities 0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.   unable to upgrade


Grammaticality of 'that' relative clause in phrase beginning with possessive pronoun

I would like to ask about the grammaticality of a 'that' relative clause modifying a noun phrase that begins with a possessive pronoun. Please consider these examples:        Please send in your technician that I can talk to.   They scrapped our project that had taken us so much effort.      From a somewhat prescriptive standpoint (I'm trying to quit...), I would like to ask whether this construction might require the 'that' pronoun to be replaced with the stronger alternatives, 'which' or 'who', also preceded by a comma.        Please send in your technician, who I can talk to.   They scrapped our project, which had taken us so much effort.      Alternatively, beginning the noun phrases with an indefinite article would then allow the 'that' relative clause.        Please send in a technician that I can talk to.   They scrapped a project that had taken us so much effort.      I would really appreciate knowing your views on this--particularly on the ungrammaticality I see in the first examples.  Thank you very much.


Verification not working for Uncaught TypeError: Cannot read property 'top' of undefined

I have a script that is designed to make an element sticky when it reaches a specific point on the page.  That is working correctly, however on some pages that section doesn't exist (by design).  As a result I am getting an Uncaught TypeError.  I have tried a few methods of verifying the var but it's still not working correctly on pages without the JumpTo div.  Here is my code:  jQuery(document).ready(function() {     var jumpToTop = jQuery(".jump-to").offset().top - 160;     if (jumpToTop !== undefined) {         jQuery(window).scroll(function() {             if (jQuery(window).scrollTop() > jumpToTop) {                 jQuery(".jump-to").addClass("sticky-jump-to");             } else {                 jQuery(".jump-to").removeClass("sticky-jump-to");             }         });     } });   Please help me with the verification or other method so that the function only runs when .jump-to is present and I don't get the Uncaught TypeError.


div element not found while using $A.createComponent

I am trying to create a div using $A.createComponent but its throwing error.  `$A.createComponent("aura:HTML",         {              "tag": "div",             "HTMLAttributes":{"id": "filter-"+ component.get('v.index') +"", "Text":"Test"},             "class":""         },         function(result, status, errorMessage){              if (status === "SUCCESS") {                 $A.createComponents(components,                                     function(components, status, errorMessage){                                          if (status === "SUCCESS") {                                            var divElement = document.getElementById("filter-" + component.get("v.index"));                                            //var divElement = component.find(component.get('v.targetDiv'));                                            console.log('Div element');                                            var elementBody = divElement.get("v.body");                                          }                                      }                                      );                        }           }        );   Please ignore if any missing brackets are there I may have made mistake while copying it.  It throws that divElement does not have get method or divElement is undefined. I know that component.find(component.get('v.index')) is trying to assign some value which never exist.  how can I over come this situation?


I'm working on a model at the moment and I've spent hours texturing the torso of my character. The node setup is okay (I think), the paint worked perfectly, it was all fine and dandy until I stopped to texture a 2nd object. As soon as I had done this, the texture on the first object disappeared entirely, to be replaced with solid black. I suspect it might be something simple, but I honestly can't for the life of me figure it out & would really appreciate some help.  P.S I did UV unwrap, did create an image texture, and the image texture is still saved in the blend file. Did I need to save the UVs somehow perhaps?


I want to write an equation with bold extended brackets.  For example:  \begin{equation} x_k = \left[\begin{matrix} 1 & T_s & \displaystyle \dfrac{T_s^2}{2} \\ 0 & 1 & T_s \\ 0 & 0 & 1\end{matrix}\right] x_{k-1} + \xi  \end{equation}   But I can't obtain bold brackets ([ and ]).  Thank you for helping.


I've got a function, $r(\theta)$, of the radius of an ellipse relative to one focus of the ellipse: $$ r(\theta) = \frac{l}{1 - e\cos \theta} $$ where $e$ is the eccentricity and $l$ is the semi-latus rectum.  I've also found an equation for the arc length from $\theta = 0$ as a function of time, $L(t)$. ($L(t)$ is a bit of a mess, so I'll leave it out unless someone wants to see it).  I'm trying to find $\theta$ as a function of $t$, so that I can use that in conjunction with my ellipse equation to find a parametric form of the ellipse, $\bigl(r(t),\,\theta(t)\bigr)$. The only way that I can think to do this is to solve the equation $$ L(t) = \int_0^t \!\sqrt{r^2 + \left(\frac{\mathrm{d}r}{\mathrm{d}\theta}\right)^2}\mathrm\;{d}\theta $$ for $\theta$. However, this is proving to be beyond both my and Mathematica's abilities. Is there a better way to get $\theta(t)$?


Beamer navigation bar content overflowing

I am creating a presentation in LaTex using the beamer document class. I am using the Hannover theme. This produces a navigation bar on the left hand side of each slide.  I have a lot of sections and subsections. These are indicated on the navigation bar. The problem is that these overflow the navigation bar. Neither do I want to delete any section or subsection nor do I want to make the text in the navigation bar smaller.  But still, I want the navigation bar to show all the "relevant" sections and subsections (along with the previous and next ones). How do I achieve this?  Edit 1  Here's an MWE (a screenshot of how the navigation bar looks like when there are too many sections and subsections):   As you can see, the navigation bar is overflowing. I do not want this to happen. Instead I want the following to happen:     Whenever I am presenting a section, only that section (and it's   subsections along with the name of the previous and next section only)   must be displayed on the navigation bar - nothing else. If I move onto   a next  section, only this section (and it's subsections along with the   name of the previous and next section only) must be displayed on the   navigation bar - nothing else.   How can I make this happen?


How to setblock a command block with a command in it during a /summon falling_block command?

I have: Passengers:[{id:falling_block,Block:command_block,Time:1,TileEntityData:{Command:"setblock ~4 ~-5 ~ command_block 1 replace {Command:"fill ~-2 ~-1 ~-2 ~4 ~3 ~2 minecraft:air"}"} (there is more code but that isn't relevant). Anyway, when I run the command block it says there is an error:     [09:59:24] Data tag parsing failed: Expected '}' but got 'f' at: ...command_block 1 replace {Command:"f<--[HERE]    Please help :V


Proving closed interval [0,1] has same cardinality as Real Numbers

I want to prove that the closed interval [0, 1] has same cardinality as Real Numbers. I was able to figure out (0, 1), but need help with proving the closed part. What I have so far is:  the function $y = tan x$ gives us a bijection between $(−π/2, π/2)$ and $R$, and that the function $y = (2x − 1)π/2$ gives a bijection between $(0, 1)$ and $(−π/2, π/2)$. Therefore $y = tan (2x − 1)π/2$ gives a bijection between (0, 1) and $R$.  How do I finish this off for the closed aspect?


Is there a known isotope that generates anti-matter?

I heard that even a banana generates a minute quantity of antimatter. Does any know radioactive nuclear reaction produce antimatter along with alpha, beta and gamma radiation?


Polylogarithms of negative integer order

The  of order $s$ are defined by $$\mathrm{Li}_s (z) = \sum_{k \geqslant 1} \frac{z^k}{k^s},  \quad |z| < 1.$$ From the above definition, derivatives for the polylogarithms immediately follow. Here we have $$\frac{d}{dz} \mathrm{Li}_s (z) = \frac{\mathrm{Li_{s - 1}}(z)}{z}.$$ When $s = 0$ the following series which is geometric results $$\mathrm{Li}_0(z) = \sum_{k \geqslant 1} z^k = \frac{z}{1 - z}.$$ Starting with the expression for $\mathrm{Li}_0(z)$, repeated application of the derivative rule allows explicit expressions for the polylogarithms to all negative integer orders to be found. The first few are: \begin{align*} \mathrm{Li}_{-1} (z) &= \frac{z}{(1 - z)^2}\\ \mathrm{Li}_{-2}(z) &= \frac{z(1 + z)}{(1 - z)^3}\\ \mathrm{Li}_{-3}(z) &= \frac{z(1 + 4z +z^2)}{(1 - z)^4}\\ & \vdots \end{align*} All are rational functions in $z$. A closed form expression for $\mathrm{Li}_{-n}(z)$ where $n \in \mathbb{N}$ in terms of either  or  can be found. In terms of Eulerian numbers $\left\langle n \atop k\right\rangle$ the result is $$\mathrm{Li}_{-n} (z) = \frac{1}{(1 - z)^{n + 1}} \sum^n_{k = 0} \left\langle n \atop k\right\rangle z^{n - k}, \quad n \geqslant 1.$$ What I wish to know is how can such a result be proved. Of course once one knows what one is looking for, the result can be readily guessed, and I suppose induction used to prove the claim is true for all $n$, but is there a way to prove the result directly?


The use of -s on third person verbs in a question starting with "does"

I was watching this video about Cyclopia on youtube and noticed this sentence: How does an animal that normally has two eyes develop just one in the center of its face.   I tried to google it but I couldn't find an answer, and it's really nagging me. So, shouldn't it be "develops" being the subject of the verb "an animal"? Btw, I also heard someone saying "It doesn't seem safe", instead of "It doesn't seems safe" in a movie. Can someone explain to me the proper usage, and if you can keep it simple, please... I'm not a native speaker, and most of my English I learned from watching movies and tv shows, I'm just now trying to learn about grammar and stuff.    Ps: Was this post to lengthy? That's my first time here on stackexchange and I'm not really sure how I should approach writing my questions.


Make it possible to log into all my SE sites at once

Welcome back Mad Scientist, you've been logged in. Click here to refresh the page.   I see than banner far too often.  SE decided in the beginning that there should be one account per site, and not a global network account. I disagree with this choice to some extent, but I'm also not really a typical user, and the choice of separate accounts has certainly some merit. So I'm not trying to convince SE to change this, but I'd like to eliminate some of the more annoying aspects this choice inflicts on users that are active on many different SE sites.  The primary annoyance for me is that I have to log into SE sites far too often. Part of the reason is that I use SE from three different desktop computers, a tablet and a mobile phone. The other part is that SE for some reason tends to forget that I was logged in. This is certainly intentional to some part, but I suspect it also happens sometimes unintentionally. Regardless, this means that I see the banner mentioned at the beginning on every single site I visit.   What I'd like to have is the option to log into all the SE sites at once. I think this would even make sense as default behaviour, but simply having the possibility to do that would be enough for me. This wouldn't create any account on sites where I don't have one, but it should log me into all SE sites at once.  This would eliminate the major annoyance that the fragmented account system causses.


Regex sometimes doesn't work as expected

I'm parsing TrackMania's .Gbx replay files. It's mixed with bytecode and XML  header part that I'm interested in. I'm trying to extract that part from replay file. For most replays it works just fine. But I encountered specific replay that breaks regex.  import re  string = r''' <map uid="Y48WnfHlw9SkYptpMIVkd0PUpRm"  name="$fffTM$09FProLeague$fff xtasis -$09F GWF$fff2018 " author="w_1r" authorzone="World|Europe|Netherlands|Gelderland"/><desc  envir="Stadium" mood="Day" maptype="TrackMania\Race" mapstyle="" displaycost="2149" mod="" /><playermodel id="StadiumCar"/><times  best="92373" respawns="1" stuntscore="7" validable="1"/><checkpoints cur="13" onelap="13"/> ''' header = r'(<header)(.*)()' print(re.findall(header, string))   Other parts of file seems like don't matter, since even with hand copied header part, regex doesn't work.   Could anyone help to find what I'm missing?


How do they make a huge crowd in a movie?

We usually see a huge crowd in a movie:   In scenes in war movies having a huge crowd, where you'll have an army force with costumes In musical shows set in a movie, games like football, cricket, or such, where they show huge numbers of fans/audience members in attendance During scenes where attendees are assembled for a speech from some leader   Process question:  How do they gather such a huge crowd? like any agency which provides huge crowds? How do crowd are made with animation techniques now-days?  Cost Question  How much do they generally pay to individual for being a part of the crowd(specify some countries examples)?


I'm new to blender. How do you change the render engine?   According to this video, the button should be along the top. I've searched google, and the blender documentation with no luck.


How to find $\int_0^2\frac{\arctan x}{x^2+2x+2}\,dx$?

Find $$\int_0^2\frac{\arctan x}{x^2+2x+2}\,dx$$   Any hints on how to approach this problem in the first place? The answer should be: $$\frac{1}{2}\arctan(2)\arctan\left(\frac{1}{2}\right)$$  I tried parts, and using $x=\frac1t$, but to no use. I also tried using an integral calculator, but it uses complex analysis, which I haven't learned yet.


Propositional Logic: $Τ\vDash\varphi\implies\existsΤ_0\subseteq T$ such that $Τ_0\vDash\varphi$

Suppose $Τ$ is an infinite set of propositional types and $\varphi$ a propositional type. Prove that if $Τ\vDash\varphi$, then a finite set $Τ_0\subseteq T$ exists, such that $Τ_0\vDash\varphi$.  I understand this is true based on my intuition but I cannot think of a strict mathematical way to justify it.   Any help would be appreciated.


No matter how thick the wall is, the player will glitch through. I've tried changing the settings on the rigidbody but nothing have worked. The walls fits together almost perfectly. Why is this happening?  I already searched a lot and also found a lot of questions regarding the same problem at "Unity Answers" - not a single one of them gets answered. I dont know why, it seems theyr community is almost dead.


why do I keep getting errors when I try to use getters to access a List I created as an instance variable for my superclass?

This is my code for the Powers superclass:  import java.util.*;  public abstract class Powers implements Sequence {    private ArrayList<Double> powers;     public Powers()    {       powers = new ArrayList<Double>();     }     public abstract List<Double> firstTenTerms();    public abstract List<Double> firstNTerms(int n);      public void setPowers(ArrayList<Double> newlist)    {       powers = newlist;    }     public List<Double> getPowers()    {       return powers;    } }   And below is my code for PowersofTwo Subclass (well, part of it, since the code is quite long):     import java.util.*;  public class PowersOfTwo extends Powers {       public PowersOfTwo()    {       super();    }     public List<Double> firstTenTerms()    {       if(Powers.getPowers().size()!=0)       {          while(Powers.getPowers().size()>0)          {             Powers.getPowers().remove(powers.size()-1);          }       }        for(int k=0; k<10; k++)       {          Powers.getPowers().add(Math.pow(2.0,(double) k));       }       return Powers.getPowers();    } }   When I try to compile the subclass, I keep on getting this kind of error message:  PowersOfTwo.java:15: error: non-static method getPowers() cannot be referenced from a static context  Or, if I just try "powers" rather than "Powers.getPowers()", I still get this:  PowersOfTwo.java:19: error: powers has private access in Powers  The problems I had encountered in classes were usually solved by using the getters, and now I am really stumped as to what to do to try fix this error. Any help would really be appreciated!


Prove that if n is a positive integer, then $\left|\frac{sin(\frac{n\theta}{2})}{sin(\frac{\theta}{2})}\right|\le n$ for $(θ ≠ 0, ±2π, ±4π, . . .)$ Any hint on how to start this question will be appreciated.


I've been trying to pair up my bluetooth keyboard with my computer after reinstalling from a standard ubuntu 12.04 to a minimal install.  In the minimal install I have no gui, so I've been trying to use the various command line tools available, but I can't figure out how the pairing is supposed to go. Pairing when I had a gui worked flawlessly.  I've asked for help here:   No one has replied but a lot of details of my situation is available there.  How is one supposed to pair bluetooth devices from the command line?


Can Non-Robot Minions be Reclaimed via Microbot Reclaimer?

When a Microbot Alpha has been played, it gives an ongoing action of     [...] All of your minions are considered Microbots.   Does this include minions in your discard pile?  The question came up in a game where a subsequent Microbot Reclaimer was played, which states:     [...] Shuffle any number of Microbots from your discard pile into your deck.   Does this combination allow for reclaiming minions "considered" as Microbots, even when they are in the discard pile as well as from another faction?


Where does Google Chrome store bookmarks on Ubuntu?

How can I get Google Chrome's bookmarks other than starting the browser and exporting?  I'm running Ubuntu.


In Python 3 when I had to merge two dicts I usually did something like this -  payload = {'key':'value'}  another_payload = {'another_key':'another_val'} final_payload = {**payload, **another_payload}   However, now when I do the same in Python 2.7 it throws a Syntax Error. Does Python2 not support it? If it supports how to do the above?


Adding a sequential number using ArcGIS field calculator to string file and keeping the 0 in front of the number?

I want to know if anyone has a code to count +1 starting at a certain number for Field Calc. ArcGIS. (I.e. 04312, 04313) It also must keep the 0 in front.  rec=0 def autoIncrement():  global rec  pStart = 040150117669  pInterval = 1  if (rec == 0):    rec = pStart   else:    rec = rec + pInterval   return rec      str(autoIncrement( )).zfill(12)   parsing error syntaxerror:invalid token (line 4)


How to prove that $|HK| = \dfrac{|H| \; |K|}{|H \cap K|}$?

I am wondering how to prove the formula $|HK| = \dfrac{|H| \; |K|}{|H \cap K|}$ where $H$ and $K$ are finite groups. Let $|H|$ denote the order of $H$ and so on.  I have seen proofs from these websites:  and .  But I do not really understand the idea of the proof. Can someone explain the proof to me, please? Thanks so much.


Why do i always get solving errors with good tracking?

So basically i am a beginner 3D modeler, i tried to 3d camera track a video but i keep getting solve errors, my tracking points are not dancing it is still as a rock, Please help me, i already tried to


unable to remove google play store search history

I see the list of internet word searches every I go to google play. No matter what settings I use the words are still there. Show searches I made on the device. But only in google playstore. It could become embarrassing. I cleared data for all application I could find use history and cache cleaners. Nothing works.


I  I can redirect all terminal output to a file, but does that work the other way around?   Can I have a terminal window open, in Tmux or elsewhere, that is receiving redirected output from a file in real time? IE if another process is writing to the file, this is being directed to a terminal window?  Use case: REPL swamped by output  The reason I would like this is I would like to see the output of some code in a REPL (Erlang it turns out) which has many processes creating terminal output stuff in background, but this output is very rapid and I "lose" my REPL command line constantly as it is drowned by the output. So I'd like those processes to output to a file instead, but, in another terminal, I still want to see what that output is in real time.


Why is there nothing on the Internet about split second ads that appear to be designed that way?

It seems to me that recently there has been an upswing in commercials that appear to actually be meant to last for less than a tenth of a second. I first started seeing them on the Late Show with Stephen Colbert, the first one being an ad for Greenpeace which would pop up after a car ad or whatever. It was just the Greenpeace logo on a black background, and was clearly readable.  I have also seen the same length of "ad" that just said it was paid for by such-and-such family, showing that family playing a board game in their living room.   I have also seen ones that seemed to be cut off from the end of fund raising ads, notably one for Doctors Without Borders, which was much harder to latch onto in freeze frame mode on my DVR than the first two examples. Are these all just cut off bits of longer ads?


How to install Linux applications onto an external hard drive

The laptop that I have acquired only came with a 16GB SSD. I installed XFCE onto it and now the SSD is almost completely full. I have an external hard drive with 1TB of memory, and I was wondering if I could move applications over to it instead of having them take up space on my SSD. I would also like to be able to access them, having the SSD inserted into the USB 3.0 slot.


What to do when you have low app space for Android 4.1 or up?

You may have already removed all possible apps that are not useful to you, But your Android phone still keeps saying insufficient memory and can't install anything because of low app space available. What will you do?


How do I use the 'scientific' mode in the Calculator?

I am trying configure the Calculator to do some binary to hexadecimal conversions but I can't seem to get to scientific mode. Please can someone tell me how I configure?


Given the sequence $(x_n)$ is unbounded, show that there exist a subsequence $(x_{n_k})$ such that $\lim(1/x_n)=0$.

Given the sequence $(x_n)$ is unbounded, show that there exist a subsequence $(x_{n_k})$ such that $\lim(1/x_{n_k})=0$.   I guess I have to prove that $(x_{n_k})$ diverge, but I don't know how to carry on.  Thanks.


Leveling bathroom floor with purlins (surface shims, leveling strips)under tub

I have a small 5 x 11 bathroom in 1961 coop/condo, wood subfloor (pictured) is not level. We don’t think water damage just building settling. This is a gut job, all fixtures being replaced. Would it make sense to use purlins then 3/4 plywood to level floor, then place new tub on new plywood?  Or backer board & tile entire floor and put tub on top of tile?  Can’t put tub on joists or current subfloor as uneven. Can’t use self leveling compound as depth of pitch too deep (1/2 an inch or more).


My teacher said that "stop to do" had two meanings: quit doing present work to do next work (which is following after the word "do") and pause for a while then continue. I have searched a lot about its meanings but what i got just about the first meaning. Is the second one true?  For examples:   I stop to play games.   First meaning: i stop doing something in order to play games.  Second meaning: i pause playing games for a while then i continue.


Prove that there exists a row or a column of the chessboard which contains at least √n distinct numbers.

On each cell of an $n \times n$ chessboard, we write a number from $1, 2, 3, .  . . , n$ in such a way that each number appears exactly $n$ times. Prove   that there exists a row or a column of the chessboard which contains   at least $\sqrt{n}$ distinct numbers.   This question is dying for a proof by contradiction, but I can't seem to show how. When I searched through the Internet, there is the following hint:     Assume each row and each column has less than $\sqrt{n}$ distinct numbers in   it. For each row or column, consider the number of distinct numbers in   it.   I feel like double counting is involved in the process, but what to count in two different ways? Also I can prove the statement with the probabilistic method but I would really like to learn the double counting approach.  Here is the other proof:  Choose a random row or column ($2n$ choices). Let $\textbf X$ be the number of distinct entries in it. Use the indicator variable $I_i$, for the existence of number $i$ in the block: $\textbf X = \sum I_i.$ Clearly, $E[I_i] = P[I_i = 1]$.  Then $P[I_i = 1] \geq 2\sqrt n / (2n) = 1/\sqrt n$. The lower bound is obtained if all the $i$ happens to be in some $\sqrt n$ edged square sub-matrix. Hence, by linearity $\textbf E[X] \geq \sqrt n$. This proves the existence.


Does a round-the-world ticket get invalidated if you miss a flight in the midst of an itinerary?

In normal tickets, it would get all of your subsequent flights invalid once you miss a flight in the midst of the whole itinerary. How about the case on the RTW ticket?  Usually the RTW ticket doesn't allow you to change the route, but allows you to change the date of the flight. If you miss a flight, can you change the date of the (missed) flight after the departure date?  Or can I buy a separate ticket by myself to make up for the missed flight and resume the remaining part of the itinerary from the next city onward?  If the specific program is required, it is the Star Alliance award ticket redeemed on ANA mileage program. But I would like to get a generic answer, if possible.


Why does a magnetic field "curl" around a current carrying element?

From all the texts I've read, it's always stated that the magnetic field would either curl or warp around the the current flowing within a conductive element, yet, I never was clarified as to why that is. Why would the field "curl" around it? I'm curious if there is an explanation for that nature.    Amazingly, it seems like a perfect circle too, similar to the diagrams that I've studied.


I know from verious other discussions that 'can not' and 'cannot' are basically both correct but 'cannot' is being used more often. Nonetheless what happens if I have a 'not only...but also' construction like in  the following sentence:  "Heat pumps cannot only be used for space heating but also for space cooling."  Is it also correct to use 'cannot' in this context?  I'd appreciate every comment.


I had a mistake with a trigger which resulted in errors in PostgreSQL 9.4.3 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit.  Each time during the error, the primary key of SERIAL increased.  After fixing the bug, the table measurements is    measurement_id | measurement_size_in_bytes |             time               ----------------+---------------------------+-------------------------------               1 |                     77777 | 2015-07-14 18:29:56.858703+03               2 |                       888 | 2015-07-14 18:29:56.882552+03               3 |                       888 | 2015-07-14 18:30:15.505957+03               4 |                       888 | 2015-07-14 18:41:01.878106+03              39 |                     77777 | 2015-07-15 12:11:21.21391+03              40 |                     77777 | 2015-07-15 12:11:59.551973+03              41 |                     77777 | 2015-07-15 12:12:05.48982+03              42 |                     77777 | 2015-07-15 12:13:02.402053+03              43 |                     77777 | 2015-07-15 12:13:02.419412+03              44 |                       888 | 2015-07-15 12:13:02.434728+03          ...   where the amount of error statements has been 35 (= 39-4).  This jump in IDs may become a challenge later when I want to integrate this table with a partial index where order matters.   Table  CREATE TABLE measurements     (         measurement_id SERIAL PRIMARY KEY NOT NULL,         measurement_size_in_bytes INTEGER NOT NULL,         time TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,         CONSTRAINT no_duplicate_measurements UNIQUE (time)     );       What are the challenges of keys with gaps?


Can I save installed packages when I need to reinstall Ubuntu?

Last night my Ubuntu system was working fine but today its getting stuck at the start screen. I can tell you my system states that Grub is working fine. My system is dual boot with Windows 7 as my other OS. and I can work on it. I have tried recovery mode options, dkgp and fsck. but still no success.  I don't have a graphics card.  I think that the only thing that is left for me to try is reinstall, but I have installed many package and spent so much time on it.   Is there a way to keep all those packages intact?  Or is there any other alternative solution?  I really don't want to spent time on installation of all those dependencies again.


Prove that $ℤ[i]^*= \{1,-1,i,-i\}$.  $\{1,-1,i,-i\} ⊂ ℤ[i]^*$ is trivial. But I'm not sure about the other inclusion.  Let $(a+bi) \in ℤ[i]^*$. Then there exist $c,d \in ℤ$ such that $(a+bi)(c+di)=1$. Then $ac+bci+adi-bd=1$. Then $bc-ad=0$ and $ac=1+bd$. What can I conclude from this ?


In python how to check if a file has already been open by other softwares? (in linux)

I am developing a software in python. It receive videos and detect if there are any porn moments, and if it detects some porn moments on this video, this software would record the video name and the specific time to a log file. If I have 2 movies ('Titanic' and 'SAMSARA') I will run this software 2 times given different movie path and after several minutes I can get the following log file generated by my softwares. ID    video_name    porn_time(h:m:s) 1       Titanic       1:12:23 2       Titanic       1:29:10 3       SAMSARA       0:45:50 4       Titanic       1:56:00 5       SAMSARA       0:49:56  Every time I want to write new row, I would read the log file to know the ID of the last row, then I set a new_ID = ID + 1, and write the new_ID and new row into the log file. I found the running software should check if the log file is open by other softwares (especially when a lot of movies are detected at the same time), otherwise the ID would be wrong or it will fail to write new row to the log file. I hope to find a way to check if the log file is open by other softwares. If so, I can wait several seconds to let others' softwares finish their job and close it. The code would be:     while True:         if file_is_open():             time.sleep(3)         else:             write_data_to_log_file()             break    gave a solution but I found it does not work on my server with linux system.


How does a string store information during wave superposition?

Given we have two Guassian wave pulses in the same medium (string) but in opposite directions. The principle of superposition states that they should pass through each other without being disturbed, and that the net displacement is the vector sum of the individual displacements.   Like this:    My question is, how does the string have 'memory' of the information on the shape and velocity of both pulses separately? For instance, consider if the interference were destructive. Then when the string is perfectly flat, it cannot have memory of what brought it to this state; similar to how a particle does not continue to accelerate after a force has stopped acting: it has no memory. I understand that although the displacement is zero, the velocity is non zero and at this point the string has kinetic energy. How can the string know from the velocities of various points which waves will emerge?  How do both the waves emerge unchanged?  I think my confusion stems from a lack of conceptual clarity on the principle of superposition, I may not completely understand it. Any help is appreciated.   Note to moderators: I request that this question not be treated as a duplicate. While there are similar questions  and , none of the answers are able to justify how this happens in terms that make sense to me.


Ubuntu installed on a pendrive - bootloader issue

In my PC I have a HDD and SSD. On my SSD I have installed Windows 8.1, and my HDD's sole purpose is to hold some data. I needed access to Ubuntu, so I installed in on a pendrive and it's working fine if I've choosen booting in Legacy mode (and put pendrive before SSD with Windows bootloader). However, it doesn't work in UEFI mode at all. I don't want to use this Legacy mode, as I want my Windows to be available ASAP and UEFI simply works faster. However, I want my Ubuntu start if this pendrive is attached to my laptop. During installation I showed that I want to have bootloader installed on my pendrive. What can I do? My version - Ubuntu 14.04LTS.


There is only a little/little tea in the teapot, which one is correct? I'm confused. When only is used, do we add or drop the article "a"?


Can a willing lycanthrope be True Polymorphed?

Can a lycanthrope or other shapeshifter be willingly affected by the spell True Polymorph? I know that it can be affected by regular Polymorph, but the text for the enhanced version seems to differ.


How occurs the enantiomorph of the mirror?

How occurs the  of the mirror?  I would like to know how occurs the RELATIONS OF THE RAYS with the mirror and the image, everything that happens to be flipped image from the right to the left.


Podcasting seems to be exploding these days but I was wondering if anyone has come across a podcast or podcasts explores the stuff that is happening out there in the geospatial world?  I have found one that a really like "" but I would love to hear if anyone out there that has any other recommendations.


Uppercase the keywords in a string in C# (SQL Beautification with keywords)?

I have some keywords  private static readonly string[] Keywords = {   "SELECT", "FROM", "WHERE", "GROUP", "HAVING", "ORDER", "LEFT", "RIGHT", JOIN", "INNER", "OUTER", "ASC", "DESC", "AND", "OR","IN", "BETWEEN", "BY", "NOT", "ON", "AS", "CASE", "WHEN", "ELSE" };   I want to uppercase these keywords in a string    string Query = "Select * fRom TableA"   This string should be converted to SELECT * FROM TableA  That is, Case will be ignored and keywords will be uppercased.  For this, I have written a function      public static string GetUppercaseKeyword(string sqlStr)     {         string sqlText = string.Empty;         int foundAt = 0;          foreach (var keyword in Keywords)         {             if (sqlStr.IndexOf(keyword, foundAt, StringComparison.CurrentCultureIgnoreCase) == -1)             {                 continue;             }              sqlStr = Replace(sqlStr, keyword, keyword.ToUpper(), StringComparison.OrdinalIgnoreCase);         }          return sqlStr;     }   and the replace function is    public static string Replace(string str, string old, string @new, StringComparison comparison)     {         @new = @new ?? "";         if (string.IsNullOrEmpty(str) || string.IsNullOrEmpty(old))             return str;         int foundAt = 0;         while ((foundAt = str.IndexOf(old, foundAt, StringComparison.CurrentCultureIgnoreCase)) != -1)         {             str = str.Remove(foundAt, old.Length).Insert(foundAt, @new);             foundAt += @new.Length;         }         return str;     }   The thing that happens here is, if a substring matches with the keywords, the method uppercase the substrings, as in Replace method I use IndexOf  For example, select * From OrderTable will output SELECT * FROM ORDERTable.  How can I solve the problem?  My other questions are, is there any easy way to implement it? Is there any existing algorithm for this type of purposes?


Check if string contains an @ symbol or if the string is null

Basically, I have a form where people can enter stuff in, and there is one part where they input an email address. Sometimes, people just put in their name and don't put an actual email address. Sometimes they do not fill it out at all.  Is there any easy way to check to see if the string has an @ symbol in it and check to see if its Null?   Any help is appreciated


Stack that returns the minimum value in Java

I'm trying to implement a stack that apart from offering the standard push and pop also returns the minimum value in O(1) time.   This is my code.   import java.util.Comparator; import java.util.Iterator; import java.util.ListIterator;  public class MinStack<T> {      private Node head;     private Node minHead;     private T minValue;       private class Node<T extends Comparable<T>>  {         private T data;         private Node next;          public Node(T data){             this.data = data;             this.next = null;         }          public int compareTo(T other){             return data.compareTo(other);         }      }      public void push(T item){         Node p = new Node((Comparable) item);         if(head == null){             head = p;             minHead = p;             return;         }         p.next = head;         head = p;          if(((Comparable) item).compareTo(minValue) < 0){             minValue = item;             Node m = new Node((Comparable) item);             m.next = minHead;             minHead = m;         }      }      public T pop(){         if(head == null){             System.out.println("Popping off an empty stack!!!");             System.exit(-1);         }         Node item = (Node) head.data;         if(item == minValue){             minHead = minHead.next;         }         head = head.next;         return (T) item;     }      public T getMin(){         return minValue;     }      public void trace(){         Node current = head;         while(current != null){             if(current.next == null){               System.out.println(current.data);             }else{                 System.out.println(current.data + "->");             }             current = current.next;         }     }      public void minTrace(){         Node current = minHead;         while(current != null){             if(current.next == null){                 System.out.println(current.data);             }else{                 System.out.println(current.data + "->");             }             current = current.next;         }     } }   When i use the following client code,  MinStack<Integer> stack = new MinStack<>();         stack.push(12);         stack.push(1);         stack.push(7);         stack.push(9);         stack.push(3);         stack.push(2);         stack.trace();   I get a null pointer exception at the line where the T values are compared using the compareTo function. Can someone help me understand what am I doing wrong here.


1920 1080 resolution is not showing up [VBOX Cent OS 6.6]

MY /etc/X011/xorg.conf has the following configuration, but its not showing up 1920x1080 resolution in Guest centos 6.6  Section "Monitor"         Identifier   "Monitor0"         VendorName   "Monitor Vendor"         ModelName    "Monitor Model"         HorizSync   28.0 - 70.0         VertRefresh     56.0 - 75.0 EndSection  Section "Device"         Identifier  "Card0"         Driver      "vesa" EndSection  Section "Screen"         Identifier "Screen0"         Device     "Card0"         Monitor    "Monitor0"         SubSection "Display"                 Viewport   0 0                 Depth     24                 Modes     "1152x768" "1920x1080"         EndSubSection EndSection   Anyone facing this kind of issue ? Please help


Boot to command line without loading GUI

I'm running Ubuntu server 19.10 In order to do a few things I installe KDE-Plasma desktop.  But I still want to just boot into TTY command line without loading the GUI etc. I don't want to remove plasma, just not load any of it at boot. Ctrl-Alt-F3 works but still seems that it loads a lot of processes (sleeping but still).  Thank you for any help!


Multiple correct question based on permutation group

I try to solve this the number of permutation in $S_{n}$ for $n\geq 4$ which are product of two disjoint $2$-cycles is $\frac{n(n-1)(n-2)(n-3)}{8}$. So after putting $n=5$ and $n=4$ I get different answer. Am I right ? Please help how to solve this. Thanks.


What's the difference between:     " I'm short, I would have liked to be taller."      " I'm short, I would like to be taller. "


Cancer patient travels back in time to WW2 to prevent the development of a cure for cancer

Looking for the name of a story about a time traveler who goes back to WW2 England to prevent the development of a cure for cancer. The traveler is a well known cancer patient, who appears at a clinic where a doctor has made a breakthrough discovery that will lead to a cure for cancer. The doctor does not even know the implications of his discovery yet, and the traveler eventually morphs himself into a bomb and blows up the doctor, himself, and the lab.


Choice between past tense and present tense?

Todd is asking Dan about his concept of slow travel. The following passage is part of  Dan's reply.     Yeah, I mean especially maybe because I'm a blogger, we're always   seeking to define things in unique ways. And there’s a lot of terms   out there. There’s expat; people that have left their native country.   There’s backpacker, which is someone who tries to keep their cost very   low and they’re continually moving from place to place. There’s flash   packer, which is a term that means you still have income from   somewhere and you have more tech and toys, and you stay at maybe nicer   hotels.      But what I did was always a little bit different, which is I would go   and get long term leases or medium term leases at apartments. So I   would go and get a house or an apartment in a place for anywhere from   one to six months, and enjoy what it feels like to actually live   somewhere.And that to me is so exciting, you know. Although the   sights and everything are cool, and hanging out with tourists can be   fun, I much prefer to go down to the local café, open up my laptop,   talk to the people that are working there, and really get a sense for   what it’s like to live in a city. (From   )   At first the speaker is using the present tense (the entire first paragraph). Then he suddenly starts using the past tense(did, would go, would go), and then returns to the present tense again.   The speaker could well have said the following instead to keep the tense consistency.      But what I do is always a little bit different, which is I go and   get long term leases or medium term leases at apartments. So I go   and get a house or an apartment in a place for anywhere from one to   six months, and enjoy what it feels like to actually live somewhere.   I want to know why the speaker chooses the past tense over the present tense in the beginning of the second paragraph.  Thanks for the comments and the answer which help me clarify my question.


I'm trying to create a 3D textured model of a boomerang based on this image  I have a good model and have applied a wood texture to it, but I'm pretty stumped when it comes to creating the designs in a way that looks convincing. If anyone knows a good way to approach this the help would be greatly appreciated. Here's my model so far:


Identity link and log link in Poisson regression

Can anyone please explain the identity link and log link in Poisson regression with simple example? For example, I have run a script using the mtcars data set in R.    head(mtcars)  glm(mpg~disp+hp+wt, data=mtcars, family=poisson(link="identity"))   mpg, disp, and wt are variables in the data set. I got the results:    (Intercept)= 35.205669 Coefficient of disp=-0.004313 Coefficient of hp=-0.028214 Coefficient of wt=-3.102409   How do I interpret these coefficients? How does the model look like mathematically? What does link="identity" mean in the model?


How did they simplify normal equations for OLS in linear regression?

How did they go from (1) to (2): \begin{align*}       S_{xx} &= \sum(X_i - \bar{X})^2 \tag1 \\               &= \sum(X_i - \bar{X}) X_i \tag2 \\              &= \sum X_i^2 - \left(\sum{X_i}\right)^2/n \\              &= \sum X_i^2 - n \bar{X} \end{align*} In (2), are they simply saying that $(X_i - \bar{X}) = X_i$? Why is that so?  It is also seen here in OLS equation: $$b_1 = \frac{\sum X_i Y_i - \left[\left(\sum X_i \right) \left(\sum Y_i \right)\right]/n}{\sum X_i^2 - \left( \sum X_i\right)^2 /n} = \frac{ \sum\left(X_i -\bar{X}\right) \left(Y_i - \bar{Y}\right)}{\sum \left(X_i - \bar{X} \right)^2}$$  The technique is used again in the denominator, when they go from middle equation to the right. Why is it?


How to linkify urls in a string with php?

I have the following strings having pattern which given below:  1)click on http://www.google.com  2) click onhttp://www.google.com".  3) click on www.google.com  4) click onwww.google.com  5) click on www.google.com#xyz  6) click onwww.google.com#xyz   I need to convert all these string to below manner with using of regular expression:  click on http://www.google.com  click onhttp://www.google.com  click on www.google.com  click onwww.google.com  click on www.google.com#xyz  click onwww.google.com


How do I test an application for SQL injections?

I'm supposed to test a web application for SQL injections. I'm new to this type of security testing and I'd like to get some tips on the matter. Are there any best practices or do I simply search on the Internet for the most common SQL injections and try them out on my application?  I hope some guidance would be profitable for other newbies like me, so please, help me complete the following lists:   List of "places" in the application to be tested:   username  password(s)  e-mail search field  text fields any other fields that are available to the user  List of tests to be performed:   ...?    Thanks!


Add a way to dismiss the "Internet Explorer is no longer supported" banner

When browsing the site using Internet Explorer, a new banner indicating that IE is no longer officially supported appears:    Unfortunately, there is no way to dismiss this prompt. Can there please be a way to dismiss this prompt? (Especially since there are platforms on which it's not possible to install other browsers, e.g. Windows RT or some older company PCs.)


How to derive "a blob of water in space becomes a sphere" analytically?

I'd like to understand better the assertion that planets are spheres because of gravity.  The thing which I believe is true, but don't completely get, is that any arrangement of a sufficient number of molecules, all with zero velocity, in isolation from anything else, will over time form a sphere due to gravitational attraction between the molecules.  If this is true, what is the argument for why this will happen? (i.e. what is the proof that I can't construct a weird initial arrangement of molecules for which it won't happen?) Can we do some math and see it pop out? If this is false, what additional stipulations do I need?


Why did the writers select the date November 5, 1955 in Back to the Future?

Is there any significance to the date November 5, 1955 that was chosen in Back to the Future? Is it one of the directors birthday or something like that or were there specific real life events that day in history?   I am not looking for in-universe answers.


'$' predefined shell variable (called as "$$"). What does it hold?

I had a typo and wrote $$ in a bash script (as argument to echo).  It printed a number (1979).  I tried many times, and all of them printed the same number, so I thought it might have to do with the Unix epoch.  I didn't find any information about it in the bash manual, or in the internet at all.  Then I tried on a basic sh; it printed a different number, 5755, and after closing and opening a new sh, it printed a slightly different number. What is that variable supposed to hold?  What is the meaning of that number?


I have to prove that. While I know this is true by thinking about it I'm having a lot of trouble actually writing the proof


On an expansion of $(1+a+a^2+\cdots+a^n)^2$

Question: What is an easy or efficient way to see or prove that   $$ 1+2a+3a^2+\cdots+na^{n-1}+(n+1)a^n+na^{n+1}+\cdots+3a^{2n-2}+2a^{2n-1}+a^{2n}\tag{1} $$   is equal to   $$ (1+a+a^2+\cdots+a^n)^2\tag{2} $$   Maybe this is a particular case of a more general, well-known result?   Context: This is used with $a:=e^{it}$ to get an expression in terms of $\sin$ for the .  Thoughts: I thought about calculating the coefficient $c_k$ of $a^k$. But my method is not so obvious that we can get from $(1)$ to $(2)$ in the blink of an eye.  $\mathbf{k=0}$ : clearly $c_0=1$.  $\mathbf{1\leq k\leq n}$ : $c_k$ is the number of integer solutions of $x_1+x_2=k$ with $0\leq x_1,x_2\leq k$, which in turn is the number of ways we can choose a bar $|$ in $$ \underbrace{|\star|\star|\cdots|\star|}_{k\text{ stars}} $$ So $c_k=k+1$.  $\mathbf{k=n+i\quad(1\leq i\leq n)}$ : $c_k$ is the number of integer solutions to $x_1+x_k=n+i$ with $0\leq x_1,x_2\leq n$, which in turn is the number of ways we can choose a bar $|$ in $$ \underbrace{|\star|\star|\cdots|\star|}_{n+i\text{ stars}} $$ different from the $i$-th one from each side. So $c_k=(n+i)+1-2i=n-i+1$.


Why does my Properties panel cover my whole active 3D Viewport when I press P? It never used to do this, it always toggled my Properties panel open and closed, as it should. But just starting today, when I press P, it covers my whole active viewport, but it doesn't even show any of the properties on the panel. Also interesting is that once the panel has covered the viewport, pressing P again will not close it again -- the only way to get it to close is press ESC, and then the panel just goes back to being open normally, not fully closed:      By the way, I'm using 2.70, and this problem continues even if I quit & restart Blender, and also if I reboot my computer.      Also interesting is the fact that if the Tools panel is open when I press P, the Properties panel will cover even it:


I have run following command accidentally   sudo chown [username] -hR /   Now sudo su getting error:  sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set   How to Solve This?


Prevent shutdown if user locks machine in Windows 8.1

I lock the PC when I leave it unattended, but the lock screen has a GUI power button which my child likes to click when no-one's looking, so often I lose work. How can I disallow soft power cycling while the lock screen is up?


I still have doubts about the subject. I need help.  Are there really open axioms?  I do not think so. What exists, in fact, I think, are seemingly open axioms, with some implicit quantifier.  For example, when it is stated that x = x is an equality axiom, it seems to me that the following statement is implicit: for every x, x = x.  Am I right?


How are White Walkers created in Game of Thrones?

Does anyone know how White Walkers were created and why? Or who they were created by?


Is it possible we've got too many Stack Exchange sites/categories?

Consider the question   Asymptotic notation questions have been pretty standard for Stack Overflow.  This fairly interesting beginner question is up, but has already accumulated a couple of 'close' votes.  One of them is for 'off topic' but, possibly because I'm a theory guy, it seems very much on topic for programming and related topics.  You could argue for "computer science" potentially, but it would seem this, like questions on, oh, NP-complete problems and such, are things serious professional programmers should know and are interested in.  You could also make a case for mathematics and event the theory stack, although it's probably a little light for theory.  But with all of these separate categories, there seems to me to be a real risk that interesting questions will be modded/closed/moved until the OP loses interest.  Perhaps we've gotten a little too compartmentalized?


if $A_n \longrightarrow \infty $ and $B_n \longrightarrow \infty $  then $(A_n+B_n) \longrightarrow  \infty$.  How do you prove it?


Difference between the use of double quote and quotes in python

Is there any difference between the use of double quotes to single quotes in Python?   "A string with double quotes" 'A string with single quotes'   Are they identical? Are there differences in how python interprets these strings?


I don't see the pattern.. does anyone understand this..?

Note.. the numbers are actually in a 7 x 6 grid.. graphics did not show here..  What is the number in the * cell? 88      63                   25      9                    16      24                   13      49                   *       10                     9      Possible answers  15  52  25  17


Best practice for a Java method returning multiple values?

I need a non-static instance method to return multiple values. For the sake of a simple example let's say these are boolean success and Object obj - but in the general case there could be more and they could be unrelated to each other. Can think of a few different ways of doing this:  Solution 1  private boolean aMethod(int aParam, Object obj) { ...set obj parameter & return value... }   Solution 2  private Pair<Boolean, Object> aMethod(int aParam) { ...set return pair values... }   Solution 3  private Object obj; ... private boolean aMethod(int aParam) { ...set obj field & return value... }   Solution 4  private class MethodReturn { // Nested class - could be a separate class instead     boolean success;     Object obj;     // ... Getters and setters omitted for brevity }  private MethodReturn aMethod(int aParam) { ...set return object values... }   Are there any more possibilities I might have missed? And could anyone comment as to the pros and cons of each (and ideally, which might be the best to use under most circumstances)?


How to provide a picture for a 'global' class?

Is there a way to provide pictures for a 'global accessible' class file?  To use my own class and style files from everywhere, I put them in      C:\Users\myself\AppData\Roaming\MiKTeX\2.9\tex\latex\myfiles   One class file contains a titlepage  \ProvidesClass{classMyClass}[2014/05/06 my own class] \LoadClassWithOptions{scrreprt}  \newcommand{\myTitelblatt}{     \begin{titlepage}         \includegraphics[width=8cm]{./pics/header}     \end{titlepage}   Now I access the from let's say      C:\myTexts\myText.tex   \documentclass{classFestoDocu_fbwk} \begin{document} \myTitelblatt hello \end{document}   Is there a way I can provide the picture 'header' for the titlepage in the class file the same way as the class file itself? I want no subdirection 'pics' in C:\myTexts\but in C:\Users\myself\AppData\Roaming\MiKTeX\2.9\tex\latex\myfiles.


What's the inverse operation of exponents?

You know, like addition is the inverse operation of subtraction, vice versa, multiplication is the inverse of division, vice versa , square is the inverse of square root, vice versa.  What's the inverse operation of exponents (exponents: 3^5)


Communities list is counting my reputation wrong on some sites

I have 101 rep on  and am not suspended there. But the site switcher thinks I only have 1 rep there:     I noticed this after I .   To test this, I just added Expats and Reverse Engineering to my site switcher list. On both of those sites I have 101 rep and am not suspended. Results:    Huh?


What's the best new feature/change of iOS7.0.1, iOS7.0.2, and iOS7.0.3?

One feature/change per post.  Please search the current answers before listing yours.  If it's difficult to explain with words, please use pictures.  Changes that can increase productivity of the user, consumption of media are likely to attract more votes.  The change could have been made in any current revision of iOS7, but has to still be available in iOS7.0.3.


I have a set up to kill all hostile mobs the minute they spawn on my server, should I just always have a /clear kind of command running? Or is there an alternative way to make it so people can get stuff from mining and such?


Java SE 14 installation , how to do with 20.04

As the title say,  I am new to Java SE 14 , what is the process to install it on ubuntu 20.04


Why are we still teaching Newtonian physics if it's "false"?

Why are we teaching an outdated theory when the math in general relativity isn't that hard? I really don't see a reason why we should teach a highly oversimplified theory in our schools. For me, it's like teaching that atoms are small balls that cannot be divided any further.


What's the difference between "made from" and "made of"? Could anyone give me some examples?


I had installed MS Word through Wine on my Ubuntu Desktop. It work perfectly.  But everytime when I run MS Word 07 I have error message. If close this a error window. Word still runs and works fine.    How to fix this pesky message ?


Use the definition of the derivative to find $f'(x)$ for $f(x)=\sqrt{x-2}$. I don't even know where to start with this. I have done $\sqrt{x-2}= (x-2)^.5$.  Is this correct?


How to make fresh new hard drive partitions during ubuntu installation

Currently I have no partitions only a single 500(488)GB drive. I want to format the hard drive and make fresh new partitions.  How do I do this?


I love to use mathfrak letters.  However I need an `A' and the mathfrak A looks a lot like a U to me:      Are there alternative `mathfrak' looking fonts?


What is the lowest frequency of light that can be found in nature?

To be more specific can an electron emit any wavelength thus frequency of light and if so is it likely to do so in nature (outside lab)? I'am a student so excuse me if the question is illogical. Thank you for your time all answers are welcome!


Construction of matrices under ZFC axioms

Do anybody know how matrices are built into ZFC theory ? I pretty have no idea how to build them from ZFC axioms. I would like a constructive proof of their existence if possible.  Thanks in advance.


proxy:error AH00898: Error during SSL Handshake with remote server

I have a server that acts as a front-end for a cPanel mailserver in a network. The apache proxy on the front-end server ran for 152 days without fault then suddenly I now get 500/502 errors when using it to access the webmail clients of the mailserver.  The front-end server uses a signed SSL cert, the cPanel sever is using a self signed cert. Here is the error log output from the front-end server when it first started happening:   [Tue Sep 10 18:22:52.959291 2013] [proxy:error] [pid 19531] (502)Unknown error 502: [client 173.xx.xx.xx:9558] AH01084: pass request body failed to 184.xx.xx.xx:2096 (184.xx.xx.xx), referer:   [Tue Sep 10 18:22:52.959469 2013] [proxy:error] [pid 19531] [client 173.xx.xx.xx:9558] AH00898: Error during SSL Handshake with remote server returned by /cpsess12385596/3rdparty/roundcube/, referer:    The front-end server is an EC2 instance running Apache/2.4.6 (Amazon) My VirtualHost setup for the proxy on this server is as follows:   < VirtualHost *:2096>     ServerName domain.com  SSLEngine on SSLProxyEngine on SSLProxyVerify none SSLProxyCheckPeerCN off  SSLCertificateFile /x/x/x/domain.com.crt SSLCertificateKeyFile /x/x/x/domain.com.key SSLCACertificateFile /x/x/x/domain.com.cabundle  ProxyPass / https://184.xx.xx.xx:2096/ ProxyPassReverse / https://184.xx.xx.xx:2096/ ProxyPassReverseCookieDomain 184.xx.xx.xx:2096 domain.com ProxyPassReverseCookiePath / /  SetOutputFilter INFLATE;proxy-html;DEFLATE ProxyHTMLURLMap https://184.xx.xx.xx:2096 /   < /VirtualHost>   As far as I can think nothing has changed on the front-end server, I didn't do an update or anything, once noticing this problem and fiddling with no success I tried a restart on both servers but it did nothing to fix this.  Any suggestions?


Insert tex code in pdf document as metadata

I am trying to save the LaTeX code needed for generating some document in the document itself as metadata. So far I found the command to set the pdf metadata using the hyperref package but now I am stuck....  This clearly does not work..  % file.tex \documentclass[a4paper,10pt]{report}  \usepackage{hyperref,listings}  \hypersetup{     pdfauthor=myself,     pdftitle=Title,     pdfsubject={\lstinputlisting{file.tex}} }  \begin{document} Hello world   \end{document}


I recently installed Windows 10 using Bootcamp. When I try to turn up the audio nothing happens. I went into device manager and the High Definition Audio Controller has a triangle with an exclamation mark over it. I tried to update the drivers but it said they were already up to date.


Moderators should not close crap, flamebait questions, let the community

When a moderator comes across a question that deserves to be closed, they should not. This should be left to the community to handle.   Here's a fresh example right out of the Stack Overflow oven: "".   It's a crappy question, to be sure.  It is long, ranty, and flame-fodder.  It should have been closed, but not by a moderator.  It is not the moderators' jobs to decide on their own what is and is not proper content for a site.  That is the job of the community.


Hide backface with xray and object wire mode?

I'm doing retopology and find it convenient to turn on xray for the object I am building. However, I now see ngons facing away from me as well. It's hard to navigate.  I would also like to set the display type to wire (like in image below). This way the original mesh isn't hidden and I can easily create new geometry around eyes, nose and mouth without hiding them.  I guess a mirror modifier could help along the x-axis since I can eliminate that half of the mesh. But I would like it even better if I didn't see the back of the skull when working on the face.


To calculate $\lim_{x\rightarrow +\infty}\cos(\sqrt{x+1})-\cos(\sqrt{x})$ can I use prostaferesis formula?


I would appreciate some advice. We live in the UK but have a sudden requirement to visit Japan (family reasons).  My 4 month old son has a Japanese passport but his UK one will more than likely not be ready in time for the trip.  Would it be allowed for him to fly out of the UK on his Japanese passport, and also return on it, without a UK one?  Would it mean when we fly back to the UK that he is only allowed in as a tourist? Are there any other complications i need to consider?   Searched for the guidance but is hard to find anything. Many Thanks Graham


If we let $f_n$ be a sequence of functions on $[a,b]$ such that,  -there exists a point $x_0\in[a,b]$ where $lim_{n->\infty}f_n(x_0)$ exists -each $f_n$ is differentiable -the sequence $(f'_n)$ converges uniformly on $[a,b]$  I want to prove that $f_n$ converges uniformly on $[a,b]$ to some function $f$  My logic:  if I use the triangle inequality to write,  $$|f_n(x)-f_m(x)|<=|(f_n(x)-f_m(x))-(f_n(x_0)-f_m(x_0))|+|f_n(x_0)-f_m(x_0)|$$  Then I can try and apply the mean value theorem to the first term on the left hand side to prove that $f_n$ converges uniformly on $[a,b]$ to some function $f$.  The mean value theorem states,  Suppose f(x) is a function that satisfies both of the following conditions,  -$f(x)$ is continuous on the closed interval $[a,b]$ -$f(x)$ is differentiable on the open interbal $(a,b)$  Then there is a number $c$ such that $a<c<b$ and,  $f'(c)=\frac{f(b)-f(a)}{b-a}$


How can I get Explorer Search to search for #?

How can I get Explorer Search to find all and only files containing the character # ?  Here:    simply entering # gives a false result:    Likewise, entering "#" .  EDIT: Folder Options, 'Find partial matches' is checkmarked and 'Use natural language search' is not.


Want to convert Numeric value of month to text

I have a month field which stores the value of month as 1,2,3 etc. How can I convert this to Jan, Feb, March etc.  Following is my controller code:   public List<OpportunityData> getOpportunityData() { Integer regnInt = (regn!=null) ? Integer.valueOf(regn) : -1;   AggregateResult[] result = [SELECT Month__c, Sum(Rental_Revenue_Actual__c) Reve, Sum(Rental_Revenue_Goal__c) Gol FROM User_Stats__C where Year__c = '2013' and Region__c =: regnInt and District__c =: dist and Sales_Rep__c != null and Rental_Revenue_Actual__c != null and Rental_Revenue_Actual__c != 0 and Rental_Revenue_Goal__c != null and Rental_Revenue_Goal__c != 0 GROUP BY Month__c ORDER BY Month__c];  List<OpportunityData> oppsData = new List<OpportunityData>(); for (AggregateResult a : result) {     OpportunityData opp = new OpportunityData((String)a.get('Month__c'),                                               (Double)a.get('Reve'),                                               (Double)a.get('Gol'));         oppsData.add(opp); } oppsData.sort(); return oppsData; } public class OpportunityData implements Comparable { public Integer compareTo(Object o) {     return month-((OpportunityData)o).month; } public Integer month { get; set; } public Double Revenue { get; set; } public Double Goal { get; set; } public Double Attnmnt { get; set; }         public OpportunityData(String mon, Double Reve, Double Gol) {     month = integer.valueof(mon);     Revenue = Reve/1000;     Goal = Gol/1000;     Attnmnt = Reve / Gol * 100;              } public String getMonth() {  return DateTime.newInstanceGMT(System.Date.newInstance(2000, month, 1), Time.newInstance(0, 0, 0, 0)).formatGMT('MMM'); }   VF page:     <apex:chart height="350" width="700" data="{!OpportunityData}" background="#FFFFFF">     <apex:legend position="right"/>     <apex:axis type="Numeric" position="left" fields="Revenue,Goal" title="Revenue (In $ '000)" minimum="0"/>     <apex:axis type="Category" position="bottom" fields="Month" title="Month of the Year">         <apex:chartLabel rotate="315"/>     </apex:axis>     <apex:barSeries title="Actual, Goal" orientation="vertical" axis="left" xField="Month" yField="Revenue,Goal" colorset="#32CD32,#1E90FF" groupGutter="10">         <apex:chartTips height="20" width="120"/>     </apex:barSeries>     <apex:axis type="Numeric" position="right" fields="Attnmnt" title="Attainment (%)" grid="true" minimum="0"/>    <apex:lineSeries title="Attnmnt(%)" axis="right" xField="Month" yField="Attnmnt" fill="false" strokeColor="#FFD700" strokeWidth="2" Smooth="3" markerType="circle" markerSize="3" markerFill="#808080"/> </apex:chart>   Please Help.


I am sorry that my question is not whether $\sum^\infty_{n=2} \frac{1}{\ln{(n!)}}$ convergent or not.  My question is how to compute the sum of series:  $$\sum^\infty_{n=2} \frac{1}{\ln{(n!)}},$$ It is a question in a textbook, and I have worked on it for days, but fail.


Why does rotating the camera mess up camera solve?

I am working on a project using camera tracking. I have a solve error of 0.3, and when I set up the tracking scene, besides the fact that the camera is rotated incorrectly, everything works great. When I try to fix the camera's rotation, things get messed up.  I am wondering how I can fix this, am I doing something wrong? Thanks in advance!


Tikz offsets origin when compiled in XeLaTeX as compared to PDFLaTeX

In the code given below, if I compile using WinEdt and XeLaTeX, my equation comes out like:    However, when I use PFDLaTeX to compile, the equation comes out correctly:    How to get the equation to show up correctly using XeLaTeX?  Here is the code:  \documentclass{book}  \usepackage{amsmath,amsfonts,amssymb,amsthm, bm} \usepackage{tikz}  \usetikzlibrary{tikzmark,calc,arrows,shapes,fit,decorations.pathreplacing,pgfplots.groupplots, matrix} \tikzset{every picture/.style={remember picture}}  \begin{document}  \begin{equation} \tikz{\node{\subnode{d4}{$\hat{{\theta}}_{BLU}(k+1)$} = \subnode{d5}{$\hat{{\theta}}_{BLU}(k)$} + \subnode{d6} {$\mathbf{K_{B}}(k+1)$}\subnode{d7}{$\big(\underbrace{z(k+1)-\mathbf{h}'(k+1)\hat{{\theta}}_{BLU}(k)}\big)$}};} \end{equation}  \begin{tikzpicture}[remember picture,overlay] \draw[blue,thick,->] (d4) to [in=90,out=245] + (245:2.2cm) node[anchor=north,text = black] {current estimate}; \draw[blue,thick,->] (d5) to [in=90,out=265] +(255:1.1cm) node[anchor=north,text = black] {previous estimate}; \draw[blue,thick,->] (d6) to [in=90,out=265] +(279:2.0cm) node[anchor=north,text = black,text width=3cm,align=center]  {(gain)\\ The weight\\ of the adjustment}; \draw[blue,thick,->] (d7) to [in=90,out=265] +(335:1.6cm) node[anchor=north,text = black,text width=4cm,align=center]  {residual prediction\\ how far the previous\\ estimation from the \\ current measurement}; \end{tikzpicture}  \end{document}


I am using Windows 10. I am trying to install 1 open source software.  In the readme.txt of that software, it says it requires Visual C++ 2008 Redistributable. I found that my Windows already has Visual Studio 2012 Redistributable installed.  After I install the open source software, it seems that it is working, even though I haven't installed Visual C++ 2008 Redistributable.  Do I need to install Visual C++ 2008 Redistributable if my Windows already has Visual Studio 2012 Redistributable?


Typically a figure is placed at the end or beginning of  a section. How can I place a figure after I refer to it in a paragraph and after the current line?


char label[] = "Single"; char *labelPtr; labelPtr = label; cout<<labelPtr;; return 0;   The ouput with the above code is Single. I'am confused about the output.   As far as my understanding labelPtr should contain the address of label[0]. So shouldn't the output be equivalent to &label[0]?


Android: Boot BroadcastReceiver not working

My application is deigned to start a BroadcastReceiver when the phone boots up, however i get a NullPointerException. I'm not sure if I'm setting up the receivers properly.   The error i got when booting up the device, using the adb logcat command:  12-01 09:46:12.542  6465  6465 E AndroidRuntime: FATAL EXCEPTION: main 12-01 09:46:12.542  6465  6465 E AndroidRuntime: Process: com.idkbro.pashchallenge, PID: 6465 12-01 09:46:12.542  6465  6465 E AndroidRuntime: java.lang.RuntimeException: Unable to instantiate receiver com.idkbro.pashchallenge.BootReceiver: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.app.ActivityThread.handleReceiver(ActivityThread.java:2992) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.app.ActivityThread.-wrap18(ActivityThread.java) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1544) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.os.Handler.dispatchMessage(Handler.java:102) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.os.Looper.loop(Looper.java:154) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.app.ActivityThread.main(ActivityThread.java:6077) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at java.lang.reflect.Method.invoke(Native Method) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 12-01 09:46:12.542  6465  6465 E AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.content.ComponentName.<init>(ComponentName.java:128) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.content.Intent.<init>(Intent.java:4868) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at com.idkbro.pashchallenge.BootReceiver.<init>(BootReceiver.java:24) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at java.lang.Class.newInstance(Native Method) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        at android.app.ActivityThread.handleReceiver(ActivityThread.java:2987) 12-01 09:46:12.542  6465  6465 E AndroidRuntime:        ... 8 more    The BootReceiver class:  public class BootReceiver extends BroadcastReceiver {  @Override public void onReceive(Context context, Intent intent) {      if (intent.getAction().equals("android.intent.action.BOOT_COMPLETED")){         Log.i("Xu", "Boot receiver is working");       }    } }   The Manifest for it:  <receiver         android:name=".BootReceiver"         android:enabled="true">         <intent-filter>             <action android:name="android.intent.action.BOOT_COMPLETED" />          </intent-filter>     </receiver>


Configuring auto-completion with TeXstudio

TeXstudio does a pretty good job with autocompletion. For example, when I type \eqref{, it already comes with suggestions, see the example below.    However, suppose that I don't want to use \eqref but a customized command using newcommand (I do this so that I can quickly switch to different styles, e.g., some for journals/conferences "Eq. (1)" is needed, whereas sometimes "(1)" suffices). In this case, TeXstudio does not do the auto-completion, see the example below.    Is it possible to configure TeXstudio such that it does the auto-completion for custom commands that require a reference?  Note that one option is to redefine \eqref using \renewcommand, but I'm looking for another way so that I can use if for many more commands, not just for \eqref.   Here is my MWE:  \documentclass{article} \usepackage{amsmath}  \newcommand{\alternative}[1]{Eq.~(\ref{#1})}  \begin{document}     \begin{equation}         \label{eq:emc2}         E = mc^2     \end{equation}     I can refer to the equation using \eqref{eq:emc2} and using \alternative{eq:emc2}. \end{document}


I'm using overleaf and getting errors while trying to run  \subsection{Decomposition of circular functions as a product of elemental trigonometric functions \footnote{We take elemental trigonometric functions to mean circular functions having a period of $2 \pi$ (i.e. $\sin x$, $\cos x$).}}    The error im getting is:  Argument of \@sect has an extra }.  <inserted text>                  \par  l.24 ...od of $2 \pi$ (i.e. $\sin x$, $\cos x$).}}  I've run across a `}' that doesn't seem to match anything. For example, `\def\a#1{...}' and `\a}' would produce this error. If you simply proceed now, the `\par' that I've just inserted will cause me to report a runaway argument that might be the root of the problem. But if your `}' was spurious, just type `2' and it will go away.  main.tex, line 24  Runaway argument?  {\normalfont \large \bfseries }{\@xfootnote }\def \reserved@b {\stepcounter \ETC. ! Paragraph ended before \@sect was complete. <to be read again>                     \par  l.24 ...od of $2 \pi$ (i.e. $\sin x$, $\cos x$).}}  I suspect you've forgotten a `}', causing me to apply this control sequence to too much text. How can we recover? My plan is to forget the whole thing and hope for the best.


How can I check if there is a link from the current file on Linux? Say, I have:  touch foo ln -s foo bar ll foo bar  bar -> foo  foo   Now, I want to know, if there are any file linked from foo:e.g.   $magic-command foo foo<-bar


What Happens to electrons after Alpha Decay and Nuclear Fission?

Where do the electrons go? In alpha decay do 2 electrons follow the alpha particle and make stable Helium or does the larger daughter nucleus become an anion?  Also what do the electrons do in the mixture of fission and alpha decay? With Beryllium-8 it decays into two alpha particles and 4 lonely electrons or do you get two Helium atoms?If someone could add an entry to Holocron it would be greatly appreciated, thanks.


$f:\mathbb{R}\to\mathbb{R}$ is continuous and $\int_{0}^{\infty} f(x)dx$ exists  could any one tell me which of the following statements are correct?  $1. \text{if } \lim_{x\to\infty} f(x) \text{ exists, then it is 0}$  $2.  \lim_{x\to\infty} f(x) \text{ must exists, and it is 0}$  $3. \text{ in case if f is non negative } \lim_{x\to\infty} f(x) \text{ exists, and it is 0}$  $4. \text{ in case if f is differentiable } \lim_{x\to\infty} f'(x) \text{ exists, and it is 0}$  I solved one problem in past which says: if $f$ is uniformly continuos and $\int_{0}^{\infty} f(x)dx$ exists then $\lim_{x\to\infty} f(x)=0$, so the condition in one says $f$ is uniformly continuous? and hence $1$ is true? well I have no idea about the other statements. will be pleased for your help.


QGIS - Eliminate sliver polygons in standalone Python code

I am trying to remove sliver polygons under a certain area.  I need to do this in a stand alone Python script, and not from within the GUI.  Is this possible?  In standalone python I was trying a piece of code base on processing.run("qgis:eliminateselectedpolygons",\  but that is not available from an external script.  Eliminate works great if I'm in the GUI.


Difference between Small Raw, Medium Raw and Raw in Canon 70D

Canon 70D does provide 3 options of getting raw images - Small, Medium and Raw. I would like to know whats the difference between 3. Recently i did my tour and got some very good results from medium raw images. Would like to know the following things 1. I do understand size of the image varies in the 3 cases and what is the extent of information loss in Full vs Medium Raw 2. Which option to use in what condition. 3. Didn't look like 70D did any software processing in case of any of the raw images but does it w.r.t Medium and Small Raw


Suppose that there is a prime number. Now I want to approximate the next prime number. (It does not have to be exact.) What would be the time-efficient way to do this?  Edit: what happens if we limit the case to the prime number of the form $4k+1$ where k is a natural number?   Edit: it's fine to replace approximate prime number with finding any prime number that is bigger than the given prime number in a time-efficient way.


Updating JDBC using GUI jButton in Java causes java.lang.NullPointerException

I have written these two classes. First, is the GUI I created and second is the JDBC connector between Java and SQL. I want to add an update statement in my code but no matter what I have tried I get the same error.  This is for a university project. I have already tried Prepared Statement instead of Statement, I have test this query:  String query = "UPDATE user SET name = 'TEST' WHERE username = 'cleogeo'";  instead of the one in the code and I know connection and getters and setters are working properly since the rest of the program executes fine.  CandidateUI Class (GUI): Here I create "edit and save mode" in the GUI to make it easier for the user to change his profile settings.   private void EditAndSaveActionPerformed(java.awt.event.ActionEvent evt) {                                                     counter++;         if(counter%2 == 1){             changePassword.setEditable(true);             changeName.setEditable(true);             changeSurname.setEditable(true);             changeEmail.setEditable(true);             changeBio.setEditable(true);             EditAndSave.setText("Save");         } else {             changePassword.setEditable(false);             changeName.setEditable(false);             changeSurname.setEditable(false);             changeEmail.setEditable(false);             changeBio.setEditable(false);             EditAndSave.setText("Edit");             newPassword = changePassword.getText();             newName = changeName.getText();             newSurname = changeSurname.getText();             newEmail = changeEmail.getText();             newBio = changeBio.getText();             iCRUDImpl.getCandidateUI(changeUsername.getText());         }     }   Then I create getters and setters for every "new" variable.  ICRUDImpl Class (JDBC):  public CandidateUI getCandidateUI(String username) {         try{             CandidateUI candidateUI = new CandidateUI();             Statement statement = connection.createStatement();             String query = "UPDATE user SET password = '" + candidateUI.getNewPassword() + "', name = '" + candidateUI.getNewName() + "', surname = '" + candidateUI.getNewSurname() + "', email = '" + candidateUI.getNewEmail() + "' WHERE username = '" + username + "';UPDATE candidate SET bio = '" + candidateUI.getNewBio() + "'";             statement.executeUpdate(query);             return candidateUI;         } catch (SQLException e) {             return null;         }     }   The error I get is a java.lang.NullPointerException in line  Statement statement = connection.createStatement();   of JDBC.  Here is also my Connection Method:  public void openConnection() {         try {             Class.forName("com.mysql.jdbc.Driver");             this.connection = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/erecruit", "root", "");             System.out.println("Connection established successfully with the database server.");         } catch (ClassNotFoundException | SQLException e) {             System.err.println("Error: " + e.getMessage());         }     }


Can I use virtualbox with a 64 Bit image in a 32 bit host

I have Virtualbox 4.1.20 in Ubuntu 12.04 32 Bit (With PAE) and I want to run Ubuntu Server 64 Bit on the Guest. Is this possible?. I ask since I get the following warning:    I want to make sure that there is no option to "emulate" this. I have a 64 bit CPU that supports virtualization. The Intel DZ68DB motherboard with an Intel I7 2600 CPU.


Problem: Let $R$ be a ring with $1$ and $e\in R$ such that $e^2=e$. If $R$ is finite and does not contain any nonzero nilpotent element then show that $Re=eRe$.  I think I solved the problem yet I do not use the finiteness of $R$. Thus, I doubt that my solution might be wrong.  Solution:   Claim 1:  $R=ker(f)\oplus im(f)$ where $f$ is a homomorphism (with respect to $+$) from $R$ to $eR$ by $f(r)=er$.  For any $r\in R$, we can write $r=(r-er)+er$ where $r-er\in ker(f)$ and $er\in im(f)$. Thus, clearly we have $R=ker(f)+ im(f)$. Now let $k\in ker(f)\cap im(f)$ then $k=ex$ for some $x\in R$ and $ek=0$.  $$0=ek=eex=ex=k.$$  Thus the sum is direct as claimed.  Claim 2: Set $K=\{r-er \mid r\in R\}$. Then $K=ker(f)$.  Note that $K\leq ker(f)$ as $r-er\in ker(f)$ for each $r\in R$. Thus, the sum $K+im(f)$ is also direct. On the other hand, $r=(r-er)+er$ for all $r\in R$, and hence $R=K\oplus im(f)$.  Now pick $x\in ker(f)$. Then $x=k+i$ where $k\in K$ and $i\in im(f)$. Then $i=x-k\in ker(f)$, and hence $i=0$. We obtain $x=k$ and $ker(f)=K$ as desired.  Claim 3: $eR=eRe$.  We have $R=ker(f)\oplus eR$, and hence $Re=ker(f)e\oplus eRe$.  Pick $t\in ker(f)e$ then $t=re-ere$ for some $r\in R$.  $$t^2=((re)^2-re^2re-erere+ere^2re)=0$$  and hence $t=0$ by hypothesis. Then $ker(f)e=0$, and $Re=eRe$ as desired. Similarly, we would have $eR=eRe$.


This is how you type set a nested list in LaTeX:  \begin{itemize}     \item I have a house     \begin{itemize}         \item It has 4 walls         \item a roof,         \item two windows,         \item and a door         \begin{itemize}             \item with a handle             \item and a lock         \end{itemize}     \end{itemize}     \item I also have a car     \begin{itemize}         \item but I will not talk of it further     \end{itemize} \end{itemize}   This is the same list in Markdown:   - I have a house     - It has 4 walls,     - a roof,     - two windows     - and a door          - with a handle          - and a lock  - I also have a car     - But I will not talk of it further   The Latex one is really verbose. I am finding it particularly annoying when writing slides with Beamer. Nesting 3 deep is rarely a good idea, but having a list that contains  a few subitems for every item is not bad at all, but will still be uncomfortable verbose.  Is there a package that provides a alternative syntax for writing lists?    Using a few defs can help maybe, but seems hacky  \newcommand{\ol}{\begin{itemize} } \newcommand{\ole}{\end{itemize} } \newcommand{\li}{\item }   Parsing markdown lists syntax seems like it could be done with Lua, or maybe even with xargs, but I am not so great at this kinda thing (yet).


As a non-native speaker, i wonder whether there are any guidelines concerning the usage of hyphens.  Would you write      Task-planning for robots ...   or rather     Task planning for robots ...


When does sum to infinity starts getting negative?

There is a popular claim going around the internet that the sum of the positive integers is $-1/12$. There are proofs to this statement and I am not going to try and refute them. But I could not understand at what point the sum starts becoming more negative, since when I add positive numbers, the sum just gets more positive.


Can you use different Voltage and Amps to a charge phone?

If I buy a solar panel that outputs 18 Volts and between 250-300 mili-Amps will it charge my phone? I looked at the charger output for my phone and it is 5 Volts and 1 Amp.  I know that Power (units in Watts) = Voltage X Amps.  So if  18 Volts X 250 mA = 4.5 Watts (for solar panel)and  5 Volts X 1 Amp = 5 Watts (for wall charger) would my phone charge because you get roughly the same Wattage or does it have to what the charger output says?  If I use 18 Volts and 250 mA will my phone get fried?  Thank you, I am learning electricity


Proof about matrix exponentiation with conmutative matrix and Taylor series.

Exercise Let $A, B \in M_{m\times m}(\mathbb{C})$ complex matrix such that $AB = BA$. Show that $e^{A+B} = e^{A}  e^{B} = e^{B}e^{A}$. Proof: As we know, $e^{A+B} = \sum_{n=0}^{\infty} \frac{(A+B)^{n}}{n!}$ an the goal is show that this expression is equal to $\sum_{n=0}^{\infty} \sum_{m=0}^{\infty} \frac{A^{n}B^{m}}{n!\cdot m!}$ so I proceed as follows: $$\begin{align}   e^{A+B} &= \sum_{n=0}^{\infty} \frac{(A+B)^{n}}{n!} \\ &= \sum_{n=0}^{\infty} \frac{\sum_{i=0}^{n} {n\choose i}A^{n-i}B^{i}}{n!} \\ &= \sum_{n=0}^{\infty} \frac{\sum_{i=0}^{n} \frac{n!}{i!(n-1)!}A^{n-i}B^{i}}{n!} \\ &= \sum_{n=0}^{\infty} \sum_{i=0}^{n} \frac{A^{n-i}}{(n-i)!}\cdot \frac{B^{i}}{i!}   \end{align}$$ And I got stuck at this point of the demonstration. As you can see, I really feel closer to the result, but I don't know how to manipulate the last equation. I appreciate any ideas :)


Superimposing architectural models onto street photographs

I wanted to use 3D MAX to create architectural renders, but I have a Mac, so I am looking into Blender as an alternative solution.  The models look amazing and the rendering is fab, but I am struggling to find a tutorial to help me superimpose my model onto the photograph of a street or equivalent. I have to supply images of the model in situ, so I am really hoping there is a way. Please can someone help me?  Thank you


Is it possible to downgrade from Android version 4.0(ICS) to 3.0(Honeycomb) after upgrading to ICS? Can any one help me.


From George Grätzer's Book; More Math Into LaTeX (5th edition) at the subsection 2.6 Your errors: Davey's Dos and Don'ts, it is mentioned that when you submit an article to a journal,   Don't use \left\{,  \right\}, \left(, \right), and so on, [...]. Even when \left and \right do not change the size of the symbol, they add extra space after the closing delimiter.   Why shouldn't we use these very useful commands?  Is there an alternative, except manually change the size?


How can I pass a class member function as a callback?

I'm using an API that requires me to pass a function pointer as a callback. I'm trying to use this API from my class but I'm getting compilation errors.   Here is what I did from my constructor:  m_cRedundencyManager->Init(this->RedundencyManagerCallBack);   This doesn't compile - I get the following error:      Error  8 error C3867: 'CLoggersInfra::RedundencyManagerCallBack': function call missing argument list; use '&CLoggersInfra::RedundencyManagerCallBack' to create a pointer to member   I tried the suggestion to use &CLoggersInfra::RedundencyManagerCallBack - didn't work for me.   Any suggestions/explanation for this??  I'm using VS2008.  Thanks!!


I'm trying to check to see whether a file exists in a directory on Linux Mint but recieve error

I am attempting to see whether a file exists within a  directory then if it doesn't exist, create it. I'm using Anaconda and Python version 3.7.4. However when I run the code I recieve the error NameError: name 'found' is not defined. I'm using Visual Studio Code and am quite new to programming! import fnmatch  import os  print() for file in os.listdir('/home/user/CI6724_J0874321_John/'):     if fnmatch.fnmatch(file, 'CI5232_Logs.txt'):         found = True  if found:     print('File exists') else:     open('/home/user/CI6724_J0874321_John/', 'w')


Probability that two random numbers are coprime is $\frac{6}{\pi^2}$

This is a really natural question for which I know a stunning solution. So I admit I have a solution, however I would like to see if anybody will come up with something different. The question is     What is the probability that two numbers randomly chosen are coprime?   More formally, calculate the limit as $n\to\infty$ of the probability that two randomly chosen numbers, both less than $n$ are coprime.


difference between String.Empty and string.Empty

i want to know what is the difference between them and what is the posiible way to use them