Buying from Play store using a credit card with foreign billing address

Is it possible to use a credit card with a foreign billing address to buy items from a local Play store? I have a Visa credit card from a German bank with a billing address in Germany registered in my Google Wallet. I have successfully used my Wallet to pay for online purchases from several online service providers in different foreign currencies so I am sure the credit card is correctly registered in my Wallet account. However, while physically located in the UK, I cannot complete any purchase from the UK Play store. At the point when I need to select my preferred payment method from my Wallet account, it shows my registered credit card greyed out with the text "Unsupported Payment method" next to it.


Evaluate logarithmic integral $\int_{-\infty}^{\infty}\frac{\ln{(x^2+a^2)}}{x^2+b^2}\,dx$

I need help to evaluate the integral with the residue theorem:  $$\int_{-\infty}^{\infty}\frac{\ln{(x^2+a^2)}}{x^2+b^2}\,dx$$ where a,b>0 real numbers.  I think I could consider the contour integral where C is the half circle in the first two quadrant.  But I'm not sure how to continue.  Could someone help me?


Redirect to another html page using only html and javascript

How to go to another page using only html and css. I have tried with  window.location.href="admin.html";   This statement not working.  <input type="text" value="Username" name="username" />
 <input type="text" value="Password" name="password" />
 <input type="button" value="Password" name="password" value="Log In" onClick="login()" />


Do users get notifications when @ was edited in

I always wondered if users get notified about comments were their name was edited in afterwards.  Example:  I write a comment     See this link here   then I edit it to     @someuser: See this link here   Does the user get notified now?


The reverse of a subset of a tuple or list

If I have x = (0, 1, 2, 3, 4), and I want to get all the elements other the first two, but in reverse order, why is it supposed to be x[:1:-1] or x[:-4:-1] rather than x[2::-1]?


"Problem executing scripts APT::Update::Post-Invoke-Success" and dependency errors, bad interpreter etc

I keep trying to update with sudo apt-get update but run into errors after it runs and gets the update then spots and errors   Files not found Problem executing script   and so on      This is the output of the command sudo apt-get install --reinstall command-not-found    This is after redoing my sudo apt update    I tried to  do the repositories, based on the link all seems to have failed...


Overloading an operator in base and derived class

I've got a base class, Item, and derived class, Weapon & Shield. Both overload <<.   // item(base) operator overload ostream& operator<<(ostream& os, const Item& a_item) {     os << "     Item Object - " << endl;     os << "          Name: " << a_item.m_name << endl;     os << "          Cost: " << a_item.m_cost << endl;     os << "          Purpose: " << a_item.m_purpose << endl;      return os; }   And:  // weapon(derived) operator overload ostream & operator<<(ostream & os, const Weapon & a_weapon) {     os << "Weapon - " << endl;     os << "     Name: " << a_weapon.m_name << endl;     os << "     Cost: " << a_weapon.m_cost << endl;     os << "     Purpose: " << a_weapon.m_purpose << endl;      return os; }  // shield(derived) operator overload ostream & operator<<(ostream & os, const Shield & a_shield) {     os << "Shield - " << endl;     os << "     Name: " << a_shield.m_name << endl;     os << "     Cost: " << a_shield.m_cost << endl;     os << "     Purpose: " << a_shield.m_purpose << endl;      return os; }   Now, I have a vector<Item> inventory, to which I'm adding a Weapon and a Shield. When I loop through the inventory and cout the item, I get the Item operator rather than the one for that particular item. Here's how I'm calling the cout:  // person(derived) operator overload ostream& operator<<(ostream& os, const Person& a_person) {     os << "Person Object - " << endl;     os << "     Name: " << a_person.m_name << endl;     os << "     Level: " << a_person.m_level << endl;     os << "     Hit Points: " << a_person.m_hit_points << endl;     os << "     Inventory: " << endl;      for (auto i = 0; i < a_person.m_inventory.size(); i++)     {         os << "     " << a_person.m_inventory[i] << endl;     }      return os; }     My question is why is it calling the operator overload of the base, instead of the derived? Is it possible to tell it to call the one from the derived class?


How to write "References" title after each thesis chapter instead of "Bibliography"

I need to write "References" title at the end of each chapter instead of "Bibliography". My codes are simply  \begin{thebibliography}{99} .... \end{thebibliography}   I tried with adding  \addtocaptionsenglish{References}   and  \renewcommand\contentsname{References}   but they didn't work.   Thanks for your helps.


Why does "Healing" effect only apply to status conditions like daze or hindered? Why doesn't heal loss of Toughness defense if toughness the equivalent of the games HP?


Why does the universe exhibit three large-scale spatial dimensions?

Possible Duplicate:          Regardless of your favorite theory of how many dimensions the universe has in total, the universe seems to have a deep preference for displaying three fully interchangeable large-scale spatial dimensions (plus time) within any given frame of reference.  But why? That is, has anyone ever come up with a persuasive argument for why the number three is or is not the required number of large-scale spatial dimensions in a universe?   appears related, but after reading through it I'm pretty sure it is only pointing out that the known laws of electrostatics have three spatial dimensions built into them, which is most certainly true. But universes with fewer or more than three large-scale spatial dimensions would presumably have different force rules reflecting their different geometries, so this kind of analysis only shows self-consistency within a universe.  (I should also warn responders in advance that while I respect the right of some theorists to suggest that it is three "because our universe evolved that way out of a fractal multiverse," I also respect my own position that such statements are equivalent to saying "We haven't the foggiest idea why." An answer along those lines would at the very least need some powerful anthropic principle support, e.g. a proof or near-proof that universes with less or more than three large-scale spatial dimensions would have extreme difficulty supporting life.)


Which STL container should i use if:   Data is inserted and removed regularly. Data is accessed regularly at random.   E.g : dataset(4,10,15) if i want to find the closest number to 9, then it should return me 10.   I am only storing an integer. It needs to be sorted Can go to 100k datasets   I thought of using vector, but vector insertion and removing is expensive.     vector<int>   If i were to use list, i would have to access O(n) elements before reaching the data.     list<int>   I was thinking of using set as it will be good if it is sorted, but im not very sure about the efficiencies for using SET  So i hope someone can give a good solution!


Proof for f must be a constant polynomial

Suppose $f$ is a complex polynomial in $z$ and $\bar z$. Assume that $\frac{\partial f}{\partial z} = 0$ and $\frac{\partial f}{\partial \bar z} = 0$.  How do you prove that $f$ here MUST be a constant polynomial?  Thanks in advance!!!


Crontab unable to run program that calls credentials file

A newly created crontab job is failing because the program can't read a .json file containing credentials in the same directory. Both files are contained in a /home/deploy/app/ folder. Crontab executes /home/deploy/app/app which needs to read home/deploy/app/config.json to execute. The program runs fine a the deploy user, but fails when run by crontab.  I am sure this is the reason the program is failing since I directed the crontab job to log its output, and I can see that the program is unable to read the config.json file. The app has the following permissions -rwxr-xr-x 1 deploy deploy and the config.json has -rw-rw-r-- 1 deploy deploy.  The crontab entry is:  10 0,6,9,12,15,18 * * * /home/deploy/gocode/bin/BuoyBot > /home/deploy/buoybot.log 2>&1   The cron log records the error from the app, which indicates is it unable to load the config.json file stored in the same folder as the app.  error loading config.json: invalid argument   This error does not occur when the program is run manually from within the /home/deploy/gocode/bin/ folder.  UPDATE: The solution, as suggested below, was to reference the full path of the config.json file within the app (/home/user/app/config.json), rather than a reference to  the local directory (config.json).


If in a ring $R$, $x^2=x$ for all $x$ then show that $2x=0$ and $x+y=0 \Rightarrow x=y.$  I am unable to proceed. Plz help.


Let $S$  be a square of unit area. Consider any quadrilateral whose $4$ vertices lie on each side square $S$. Let the length of the sides of this quadrilateral be $a,b,c,d$. Then prove that $$2 \leq a^2+b^2+c^2+d^2 \leq 4$$     This problem appeared in IIT JEE $1997$ (re-exam).I really do not know know how to approach this problem properly.I have managed to prove $a^2 + b^2 + c^2 +d^2  \leq 4$ but not the initial inequality.


Samsung Galaxy Note 4: greyscale mode disappeared after upgrading to marshmallow

Today I've received the late Marshmallow 6.0.1 update. It has some unpleasant side effects:   Battery is draining fast Greyscale mode has been removed A very ugly grey bar is showing whenever I switch into Power Saver mode   Is there any workaround for these problems?  Config:   Model: N910c Android Version: 6.0.1 Build Number: MMB29K.N910CXXU2DPF6 Base Band Version: N910CXXU1DPC1


TeXstudio chemfig commands marked as unrecognized

I included the chemfig package to draw chemical stuff in LaTex. But the commands aren't recognized by TeXstudio. I even added the package to the autocompletion list in the settings to get recognized in every document but that doesn't help either.  The commands are red like following:     The file compiles as it should, so everything works except the recognition of the chemfig commands.


What are the white lines in some nuclear bomb test photos?

What are those white lines connecting the ground to the sky on the left side of this photo?  I've see these before in the nuclear bomb test films too.  They're apparently already in place upon detonation, as the bright backlight from the mushroom cloud suddenly makes these lines appear in the foreground.  I imagine test devices are being shot into the sky before detonation but I'd like to know more about this.  Google searching has been fruitless as I don't even know what words I'm supposed to be searching for.  Looking for a brief explanation along with a source citation.


Have upgraded from Ubuntu 16.04 - 17.04 and i noticed a lot of changes. Some good, some not so good.  1. Right click on empty space  2. Select: New Document  3. STOP  There is no Text Document option to open, instead i see a list of something that i have installed.  Where it is supposed to say: (Empty Document) I see the folders that i have saved in Templates. But no where to click to actually open an empty document.  However, if i open an already existing text document and right click on it in the menu bar then i can choose New Document and choose where to save it. But not directly in a folder or on the desktop.  P.S I for some unknown reason can not take screenshots of it.


How do I trigger capacitive touch screen electronically (without hands)?

I would like to trigger a "touch" or "touches" to a smartphone screen electronically without actually touching the screen with my finger using a remote control somehow.  The idea would be that every time I would press the remote control, it would trigger a momentary "touch" to the screen.  Is there a way to do this? If so, can someone offer a basic schematic for how something like this would be wired along with a list of suggested components?  My question was flagged as a possible duplicate but I checked the other post and so far, a solid answer hasn’t reached quite yet.   Thanks!


Does Russia/USSR have a S.H.I.E.L.D. equivalent?

In Captain America: The Winter Soldier, it's revealed that in the Marvel Cinematic Universe (MCU), there was an Operation Paperclip at the end of World War II, just as .  In the MCU, the Soviet Union counterpart to Paperclip created the Winter Soldier, so the real world projects ended up having super-science ramifications in the MCU.  On the American side of this, we see the SSR (and later S.H.I.E.L.D.) absorb these scientists and their super-science accomplishments, but what about the Soviet Union?  Did the Soviet Union (and the countries it later split into) have a S.H.I.E.L.D. equivalent?  What did they accomplish, besides the Winter Soldier?


How can I start Hoard of the Dragon Queen with 4th level characters?

I'm pretty new to DM'ing and was just wondering if there would be a way to start the hoard of the dragon queen adventure with a group of 4th level characters?  There don't really seem to be any modules for that level range yet.  We just finished a short module that took our party to level 4, but id really like to play through this adventure because it seems awesome. Also I couldn't really find any other ones that start around that level so rather than re-roll characters we'll just start a little of the way in.


There is more than one functor that fix objects in category of groups?

I am trying to solve the following exercise:  Find two functors $F_1,\ F_2: Grp \rightarrow Grp $ such that $F_i G = G $ for all $i=1,2$ and $G \in Grp$, where $Grp$ is the category of groups.   Of course the identity functor can be chosen like one of this $F_i's$ but I cant find another.   Thank's


Another way to say "hot" as in "hot peppers"?

I am making this sauce, which is extremely hot (as in hot peppers) that is being served cold (as in temperature). People who try it ask me what it is, so I say it is "cold hot sauce", which is a bit problematic, as the two are literal antonyms, even if not in the particular context.  So is there another world I could use for (extremely) hot that makes it clear it is indeed very hot? "Spicy" comes to mind but it is a big understatement. Anything else?


From the given figure, prove that      $$\cot\ \theta=\cot\ A+\cot\ B+\cot\ C$$     My work.     I have got this solution from one of my friends. But I didn't understand all the process. I understood the application of ceva theorem in the first step but the steps after that I can’t understand. Also how has be $\prod $ used here, why? How it works here?  Please make me understand


If $V$ is a finite dimensional with two norms then $\Vert v\Vert_1 \leq c\Vert v\Vert_2 $

Suppose $V$ is finite-dimensional and $\langle\cdot,\cdot\rangle_1$ and $\langle\cdot,\cdot\rangle_2$ are inner products on $V$ with corresponding norms $\Vert \cdot\Vert_1$ and $\Vert \cdot\Vert_2$. Prove that there exists a positive number $c$ such that  $$\Vert v\Vert_1 \leq c\Vert v\Vert_2 $$  for every $v\in V$.  Please help me with this question?  Edit (to be reopen). Of course, this result is a particular case of the proved result in the . But it is not a duplicate because here we want to use the fact that the norms are induced by inner products. So, is there a different proof for this specific case (where the norms has a specific form)?


Rails: How do I create a default value for attributes in Rails activerecord's model?

I want to create a default value for an attribute by defining it in ActiveRecord. By default everytime the record is created, I want to have a default value for attribute :status. I tried to do this:  class Task < ActiveRecord::Base   def status=(status)     status = 'P'     write_attribute(:status, status)   end end   But upon creation I still retrieve this error from the database:  ActiveRecord::StatementInvalid: Mysql::Error: Column 'status' cannot be null   Therefore I presume the value was not applied to the attribute.   What would be the elegant way to do this in Rails?  Many thanks.


Populate a dictionary with key value pairs by iterating through a list of keys and pairing with another dictionary

Given an empty dictionary:   matrix={}   and another list_of_dictionaries:  [{(0, 1): 3, (2, 0): 2, (2, 1): 3},  {(2, 0): 3, (0, 0): 3, (2, 1): 3},  {(0, 1): 3, (0, 0): 2, (2, 1): 1}, {(0, 1): 3, (2, 0): 1, (0, 0): 3}]   I want to iterate through a list that consists of indices:  indices=[(0, 0), (0, 1), (2, 0), (2, 1)]   and populate matrix so each i in in indices is the key, and each dictionary in list_of_dictionaries is the associated value.  I have searched and was only able to find ways to update and populate a dictionary explicitly, but in fact, I don't know what my list_of_dictionaries will contain, nor what my indices will contain. Is it correct to say, I am looking for a "dynamic" solution? I know   matrix.update(x)    will only take one argument (key or value?), but I want a solution that will take both key and value. Thanks much.  for i in indices:   The result should return matrix and look like:  (0, 0):{(0, 1): 3, (2, 0): 2, (2, 1): 3} (0, 1):{(2, 0): 3, (0, 0): 3, (2, 1): 3} (2, 0):{(0, 1): 3, (0, 0): 2, (2, 1): 1} (2, 1):{(0, 1): 3, (2, 0): 1, (0, 0): 3}


Can not connect to  HP\SQLEXPRESS  a network related or instance specific error while spablishing a connection to sql server. The server was not found or was not accessible. Verify that instance name is correct .and the sqlserver is allow to access the remote connection. error 26  Note: We are getting this error while connecting to local database on our pc. while connecting to online database its not generating this error


Is there a processor IC inside a microcontroller package?

I am reading about the TI TM4C12x microcontroller, which is available as an IC:    The datasheet of one of its variants can be found here:   On the block diagram on p. 48, it is shown that the MCU uses a ARM® Cortex-M4F processor.  Questions: Is the ARM® Cortex-M4F processor sold as an IC chip (like the common Pentium chips in desktop PCs)? I thought I would be able to find a picture of the ARM processor chip, but I was not successful in a Google search.   If the answer is yes, does TI (and other MCU manufacturers) somehow put the ARM processor chip inside its own TM4C chip, so if I cut open the TM4C chip, I would find another ARM IC inside?   If not, what exactly does TI buy from ARM?  "Appendix A. Package Information" in the datasheet does not seem to say much this.


I was writing a letter and got confused with this line.     I am thankful for the opportunities that have been provided me during   my tenure.   or should it be      I am thankful for the opportunities that have been provided to me during my tenure.


First of all, I'm kinda new to CSS, so forgive me if this is a stupid question, or my code doesn't make much sense - I've tried solving my issue, and haven't had much luck so far.  I'm having trouble centering an image, inside a div which should make a border around the image - I've made a JFiddle to further explain:    The idea is that the image should be in the center of the bordered div around it.  HTML:

   CSS:  .sponsorLogos ul li {   margin: 10px 10px;   display: inline-block;   height: 128px;   width: 128px;   border: solid 5px #e0e5eb;   overflow: hidden; } .sponsorsDiv .sponsorLogos img {   display: block;   margin-left: auto;   margin-right: auto; }   I've found a few topics on here to try and solve my problem, but haven't yet succeeded.. I know theres probably the right answer out there, but I haven't been able to find it, so sorry in advance if this question is answered elsewhere..


How can I see my notifications only every hour?

Let me apologize in advance for the bad title, but I didn't quite know how to describe it. What I want is a way for my phone to only show me the notifications from time to time instead of showing them to me as soon as they pop up.  So instead of showing me the notifications from every app as soon as they appear (which is the default) I want a way for Android to keep them hidden and just show, for example, all the notifications for the last hour at once. Then an hour from then it would show me all the notification from that hour, and so on.  I have looked at ways to do this using Android settings itself and I've looked for apps that do that, but no luck. Is there a way to do such a thing?  Thank you.


Typescript subtraction not working as expected

I have a full amount including VAT and i want to seperate the net price and the vat value.  The example is final price is 80.60 and the vat is 24%. What is the net price and what is the vat value?  The answer should be net price is 65.00 and the vat value = 15.60.  For some reason typescript calculates 65.00 and 15.599999999999994. At the moment i dont want to round, the result should be 15.60 clearly though. I know there are other ansers on how to calculate the Vat , but my question is pretty specific whats wrong with my code and generated this decimal instead of 15.60.  Here is my code: component.ts  import { Component, OnInit } from '@angular/core';  @Component({   selector: 'app-fpa',   templateUrl: './fpa.component.html',   styleUrls: ['./fpa.component.css'] }) export class FpaComponent implements OnInit {      public netPrice:number;     public fpaPercent:number=24;     public fpaValue:number=0;     public totalPrice:number;  public calc(calcType:string = ''){     this.netPrice = this.totalPrice / ((this.fpaPercent/100)+1);     this.fpaValue = this.totalPrice - this.netPrice; }  }   component.html                      <mat-form-field>                         <input [(ngModel)]="netPrice" (keyup)="calc('byNetPrice');" matInput placeholder="Net Price">                     </mat-form-field>                      <mat-form-field>                         <input [(ngModel)]="fpaPercent" (keyup)="calc();" matInput placeholder="% Vat">                     </mat-form-field>                      <mat-form-field>                         <input [(ngModel)]="fpaValue" (keyup)="calc('byFpaValue');" matInput placeholder="Vat Value">                     </mat-form-field>                      <mat-form-field>                         <input [(ngModel)]="totalPrice" (keyup)="calc('byFinalPrice');" matInput placeholder="Final Price" >                     </mat-form-field>


The simply connected coverings of two homotopy equivalent spaces are homotopy equivalent

This is exercise 1.3.8 in Hatcher:  Let $\tilde{X}$ and $\tilde{Y}$ be simply-connected covering spaces of path connected, locally path-connected spaces $X$ and $Y$. Show that if $X\simeq Y$ then $\tilde{X}\simeq \tilde{Y}$.  I tried applying the lifting criterion, but I seem to be hitting a dead end. Any help would be much appreciated.


I'm having an issue with a method that is trying to find the square root of the number. The previousG is a randomly generated number. The number is the square roots actual number. I'm getting a stack overflow error. I realize why since I'm not updating the nextGuess variable. I'm wondering what I should add to the FindTheRoot method to stop this. Furthermore, I'm doing this recursively.  public static void main(String[] args) {          int srootArray[] = {9, 17, 25, 37, 49, 55, 999};          Random randomGuess = new Random();          for (int index = 0; index < srootArray.length; index++)         {             int previousGuess = randomGuess.nextInt(srootArray[index] + 1);             System.out.println("Number: " + srootArray[index] + "... " +  "First Guess: " + previousGuess);              FindTheRoot(previousGuess, srootArray[index]);               System.out.println("-------------------------------------------- ------");         }      }      public static double FindTheRoot(double previousG, int number)     {         double errorMargin = 0.00001;         double nextGuess = (previousG + number / previousG) / 2;          if (nextGuess < errorMargin)             return nextGuess;         else         {         System.out.printf("%S%.4f%n", "Next Guess: " , nextGuess);         FindTheRoot(nextGuess, number);     }      return nextGuess; }   }


Customizing Windows 8's Windows Explorer's sidebar

I want to remove "My PC" and my username from the Windows Explorer sidebar. I just want a bunch of Favorites and the network devices. How do I do this?


I'm reading some texts that seam to assume knowledge of light that I'm not too familiar with. How does wavelength of light relate to the minimum distance span that can be observed (i.e. you cannot make a lens big enough to resolve individual atoms), and is this a light phenomena or an intrinsic wave phenomena?


Why the end-of-line % in macro definitions?

I found two things peculiar in the common style of macro definitions:   Ending lines in macro definitions with '%'; Not wrapping a macro name in braces.   Example:  \newcommand\examplemacro{%     \somecommand%     \othercommand% }   Being a software engineer first and a LaTeX user a distant second, I would expect:  \newcommand{\examplemacro}{     \somecommand{}     \othercommand{} }   Is there a reason for doing it the former way, or is it merely a matter of habit?


Someone claiming to have studied physics is telling me that spacetime is all that exists and that this fact is the basis of modern physics. When I said matter/energy also exists in its various forms, he said that energy is merely spacetime "waving/vibrating/acting", else what did I think was doing the waving: magical fairy dust? and has presented the following Einstein quote to support his claim:  "When forced to summarize the general theory of relativity in one sentence: Time and space and gravitation have no separate existence from matter."  Does Einstein's quote support what he's saying, that space-time is all that exists, and that matter/energy is spacetime waving?


If $\sum\limits_{n=1}^\infty a_n$ converges where $a_n>0,\ \forall n\in\mathcal N$, prove $\sum\limits_{n=1}^\infty \sqrt[n]{a_1a_2\cdots a_n}$ and $\sum\limits_{n=1}^\infty\frac{n}{\frac{1}{a_1}+\frac{1}{a_2}+\cdots+\frac{1}{a_n}}$ converge.  $\sum\limits_{n=1}^\infty \frac{\sum\limits_{i=1}^na_i}{n}$ diverges, so one can not use the bound of the GM-AM relation at least directly.


What are the fundamentals of implementing hook_menu()?  I would like to see the basics covered in a single question, to avoid having to answer the same similar but different questions over and over.


Where to find a direct link or torrent for Ubuntu Gnome ALTERNATE ISO?

I can't find any place to download Ubuntu Gnome 14.04 LTS in alternate ISO version.  Doesn't it exist ?


How to install latest nvidia drivers (xorg edgers doesn't work)

I 'm trying to install latest nvidia drivers (352) but it doesn't work. I tryed following:  sudo add-apt-repository ppa:xorg-edgers/ppa sudo apt-get update sudo apt-get install nvidia-352   When I tipe the last command I get  Reading package lists... Done Building dependency tree  Reading state information... Done Unable to locate package nvidia-352   What I'm doing wrong? Why xorg edgers doesn't work


A function for which one-sided limits are zero and infinity

Is it possible for a function to have a limit from the left be infinite and the limit from the right be zero, both at the same number?


Responses missing in Google Forms under the 'Checkbox - Other' question

I have a Google Form with a checkbox question and I can see from the responses summary that two respondents have ticked 'Other'.   But, I can't see what they have typed, even in the responses spreadsheet.  Where can I see what they have entered?


We had to do some configuration to our system in our company and they wanted to do these steps:   sudo vi /etc/pam_radius_auth.conf Add  *****.com ***radius 3  Add auth sufficient pam_radius_auth.so localifdown to following files just above @include common-auth:  /etc/pam.d/login /etc/pam.d/sshd /etc/pam.d/sudo  Add try_first_pass in /etc/pam.d/common-auth:  auth [success=1 default=ignore] pam_unix.so nullok_secure try_first_pass    I did two mistakes, first I added the line they said (in step three) to last file and forgot to add it to two first file:  /etc/pam.d/login /etc/pam.d/sshd   Second I added the whole line in step 4 to the end of the file instead of just concatenating to:   auth [success=1 default=ignore] pam_unix.so nullok_secure   I can not sudo any more after I restarted my system. I need to modify those files and without sudo I don't know how I should do it. I tried the recovery mode in this  and no luck. In the recovery mode it prompts me for root password and none of the password is working.  I still can login to my account but apparently my sudo user is mis configured. I appreciate any help.


Why does the kinetic energy of a particle moving in circular motion increase when the turn radius decreases and no torque is acting?

Why does the kinetic energy of a particle moving in circular motion increase when the turn radius decreases and there is no torque acting? E.g. if a planet is rotating about its axis and it shrinks to half of its radius then according to conservation of angular momentum velocity will doubled, i.e. its kinetic energy will increase. Does this mean that without any external force the kinetic energy of any thing can be increased? Please explain!


Does a "mortarboard" badge include reputation gained on bounties?

If I get/exceed a gain of 200 points in a single day (by votes) I'm "capped" at 200, but I get a "mortarboard" badge in compensation.   But points from bounties and "accepted" answers do not count toward the 200 point limit.  Yet I once got a "mortarboard" badge based on a 400 bounty that was awarded (five points that day from "normal" votes).  Was that the intent of the mortarboard badge, awarded in a situation where my reputation gain was not capped?


Environment/Macros to command line for C make file

Is it possible to substitute a macros, say #define VAL 1, with a command line argument, such as VAL=1 make? This was my approach, and I did not figure out how to change the make file. I was trying to add extra lines in .all in the Makefile, but nothing worked. So how to add a macros/environment from the command line?


My question maybe will be stupid, but my problem is that I do not understand why stream ciphers need a key and also a nonce. As far as I understand, the keystream is generated with the nonce. The same key can be reused with a different nonce.  Wouldn't be simpler just to use a new key each time? If I understand good, to decrypt the message the recipient needs the nonce. Is communicating the nonce simpler than communicating the key?


Showing a function is continuous and analytic

This is an exercise from Conway that I am stuck at. I think the function $φ$ is clearly continuous for points $(z, w)$ such that $z$ and $w$ are not equal. However I can't show that $φ$ converges to the derivative of $f$ at z as $(z, w)$ goes to points where $z$ and $w$ are equal...  Also it is clear that for each fixed $w$, $f$ is analytic for points $z$ not equal to $w$. But how can I show that $f$ is analytic at $z=w$? Could anyone please help me with this problem?


How to fill a map with the object field as key from the query?

I'm doing a query to an sObject with Dynamic apex and I would like to store al keys and values in a map where the map contains the object field as key and the value of that field from my query looking something like this:  Map<String,String> mapFieldQueryValaue = new Map<String,String>();  List<sObject> objectList = Database.query('Select Id,Name from Account');  for(sObject record:objectList){       mapFieldQueryValaue.put(sobjectField[dinamyc inject object field Name],record.Name);      //the map content would look like (Name = 'testName',Email='test@email.com')    }   There's a way to store the FieldName as my key?


How to zip multiple directories into individual zip files

I'm new to using the terminal and I found a post on here with the following code that would allow me to zip multiple directories into individual zip files but I only got it to work once.  The code is this:   for i in */; do zip ‐r "${i%/}.zip" "$i"; done   but now when ever I use it I get the following error:   zip warning: name not matched:   and when I check the folder it creates a -r.zip  file.


W, A, S, D, keys and shift aren't working together

W, A, S, D, left Shift, left Ctrl keys work individually, but when pressed together, it does not work. This prevents me from sprinting. Right shift and ctrl works fine with other keys. I have a Coolermaster keyboard, not even a year old. Should I take it to the service centre? Anyone have any solutions to offer?


How can I take an < img tag from string? Sample string is given below. But too bad name and surname parts are dynamic and sometimes image names are numbers...  Lorem ipsum dolor sit amet <img src='http://www.mydomain.com/images/name_surname.jpg' /> Sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.   What I've tried so far:  sMyText.Substring(sDescription.IndexOf("<img"), count?!);   how to count the who image character length? This is where I fail. Please help..


I can't seem to update Ubuntu; Software Updater is blank

Ubuntu Software Updater is blank when opened.     I also can't update through Ubuntu Updates in the Ubuntu Software application.   I could use the terminal but then I would have to type in my password, which I don't normally have to do for updating, and seeing as it is playing up, I guess would this be a security risk.  I have tried to remove/uninstall Software Updater but it doesn't work.


What real-world substance most closely corresponds to mithril?

While reading descriptions of mithril in The Lord of the Rings, it struck me that its properties might well correspond to a real material, possibly as an alloy with other metals. Is there such a real-world substance?


Stack exchange app should keep votes highlighted

After clicking it changes the number then changes the repective arrow back to a grey color.   Color should stay changed not revert back to grey.   Color should stay grey in situations where the user cannot vote validly for whatever reason.


We must add tags by ourselves. Why doesn't Stack Overflow automatically recommend labels or tags?


Why are fractions the same as divisions?

Ever since I learned about fractions in Elementary School, I've known how to work with them. The problem is, although I remember the mathematical rules, I don't remember how I assimilated the equality between fractions and divisions when I was younger. This is really troubling to my mind because it feels like I partly understand this concept. I know that the denominator represents the amount of parts a whole was divided into and that the numerator represents the amount of parts I'm working with. Let's say, I want to divide 3 by 4. The result of this division is 3/4. But, in this case, I'm dividing 3 wholes by 4. Doesn't this come into conflict with the definition of the denominator, which is the amount of parts in which 1 whole is divided into?   This confusion is really bugging me and I'd really appreciate if someone could clear it up. Thanks for the attention.


Can anyone explain how can i get the css property of individual class using javascript/jquery?

There is an element which has three class test,test1 and test2. Can anyone explain how can i get the css property of individual class using javascript/jquery ?
I am inside the iframe! Catch me if you can!
   If we try in browser console below code  var el = $("#myDiv"); getComputedStyle($(el)[0]);   This will get all the css property of an element, here i just want to get only the css property which is written for individual class.  If i say, get css property of the .test class then it should give the below two things:  background-color: #000; padding:20px;


Possible to change time of SO new questions digest?

I get the New questions digest message every day at ~07:56. This means that by the time I get to view/answer them, the digest message waited in my email inbox for several long hours.  Below is the settings page, and I don't see a possibility to set the time the daily message is prepared.   Is it possible to config the time when New questions are collected and sent?


Creating a list of tuples of different lists

Let's assume that I have the following three lists (l1, l2, l3). How can I create a new list where each element is a tuple of elements of the lists (l_desired)? It actually works as an extended version of the zip method in python. In simpler words, given l1, l2, l3, how can I create l_desired? l1 = [1,2,3] l2 = ['a', 'b', 'c'] l3 = ['Jess', 'Muss']  l_desiered = [(1, 'a', 'Jess'), (1, 'b', 'Jess'), (1, 'c', 'Jess'),                (1, 'a', 'Muss'), (1, 'b', 'Muss'), (1, 'c', 'Muss'),                (2, 'a', 'Jess'), (2, 'b', 'Jess'), (2, 'c', 'Jess'), ...]   `


this is my first time using linux ubuntu.  I'm trying to install java, i downloaded the file from the java website, extracted the file to the desktop and the extracted file's name now is jre1.7.0_45  i'm following this to install the java   but omg i can't even get past number 2. i get  Reading package lists... Done Building dependency tree E: Unable to locate package openjdk-7-jre   how can i do this please?


Let $G$ be a group of order $56$. (We do NOT assume the Sylow-$7$ subgroup to be normal.) Then either the Sylow-$2$ subgroup is normal or the Sylow-$7$ subgroup is normal. How to prove?  My idea: consider the case $n_2=7,n_7=8$. Then the number of elements in all Sylow $2$ -subgroups and Sylow $7$-subgroups is at most exactly $(7-1)*8+(2-1)*7+1=56$. This cannot give a contradiction. We need to prove that $G$ is simple. Then $|G||(8!/2)$. To prove $G$ simple, we need to prove there does not exist normal subgroups of order $2$ and order $4$. But I do not know how to prove.


How to undelete/restore the deleted files in ubuntu linux

Possible Duplicate:             I accidentally did rm * in a directory instead of another directory from console in a Ubuntu11 machine.is there any way to recover these files.


What are technical skills that a GIS graduate should develop?

I am a GIS Analyst with one years experience and no idea where to begin with professional development. I'm competent with the ArcGIS platform, but I am not too familiar with its administration processes. I can work with basic Python programming. I'm taking a course in SQL next week, and I'm pretty terrible with web services.  Where/How/What should i focus on learning to step up to the next level in a GIS career.


Is there an ability to not allow sudoers view your folder (only you and root can access folder)?


Failure when filtering string list with re.match

I'd like to filter a list of strings in python by using regex. In the following case, keeping only the files with a '.npy' extension.  The code that doesn't work:  import re  files = [ '/a/b/c/la_seg_x005_y003.png',           '/a/b/c/la_seg_x005_y003.npy',           '/a/b/c/la_seg_x004_y003.png',           '/a/b/c/la_seg_x004_y003.npy',           '/a/b/c/la_seg_x003_y003.png',           '/a/b/c/la_seg_x003_y003.npy', ]  regex = re.compile(r'_x\d+_y\d+\.npy')  selected_files = filter(regex.match, files) print(selected_files)   The same regex works for me in Ruby:  selected = files.select { |f| f =~ /_x\d+_y\d+\.npy/ }   What's wrong with the Python code?


Is a magnetic field just a moving charge?

I am trying to understand electromagnetism. I would like to pare myself down to the minimum number of necessary concepts.  From my physics education (high school only), I understand that a moving charge creates a magnetic field. The implication is that magnetism is a discrete concept that I also need to understand.  However, is this view actually confusing: is it the case that a magnetic field is a moving charge?  Either way, a link to a primer accessible to someone with a engineering degree level maths would be wonderful. If it is the case magnetism is a moving charge, then an introduction following this approach would be wonderful.  Thank you!


Hunting for a short story about earth having been isolated from the galactic civilization

I'm trying to find a short sci-fi story that I read some 40 years ago (in the early to mid 70's).  Earth had been isolated with some force field as Humans were regarded as too dangerous/uncivilized by the galactic civilization, but something had happened and Humans were potentially needed to help..  The story was about earth being checked out to see if Humans were now safe enough or it would be even more risk to let them loose.  The story ends with the force field being released and Earths moon being taken along by the Humans so that they would have something to remind them of home...  That's what I vaguely recall.  Any pointers would be most appreciated.


Fermions, different species and (anti-)commutation rules

My question is straightforward:  Do fermionic operators associated to different species commute or anticommute? Even if these operators have different quantum numbers? How can one prove this fact in a general QFT?


Maybe I'm searching for the wrong words but I cant find a list of commands needed to do this.  Any help would be really appreciated.  Thank you.


I am trying to execute my PHP code, which calls two MySQL queries via mysqli, and get the error "Commands out of sync; you can't run this command now".  Here is the code I am using  <?php $con = mysqli_connect("localhost", "user", "password", "db"); if (!$con) {     echo "Can't connect to MySQL Server. Errorcode: %s\n". Mysqli_connect_error();     exit; } $con->query("SET NAMES 'utf8'"); $brand ="o"; $countQuery = "SELECT ARTICLE_NO FROM AUCTIONS WHERE upper(ARTICLE_NAME) LIKE % ? %"; if ($numRecords = $con->prepare($countQuery)) {     $numRecords->bind_param("s", $brand);     $numRecords->execute();     $data = $con->query($countQuery) or die(print_r($con->error));     $rowcount = $data->num_rows;     $rows = getRowsByArticleSearch("test", "Auctions", " ");     $last = ceil($rowcount/$page_rows); }  else {  print_r($con->error); } foreach ($rows as $row) {     $pk = $row['ARTICLE_NO'];     echo '
' . "\n";     echo ''.$row['USERNAME'].'	' . "\n";     echo ''.$row['shortDate'].'	' . "\n";     echo 'DELETE RECORD	' . "\n";     echo '
' . "\n"; } function getRowsByArticleSearch($searchString, $table, $max) {     $con = mysqli_connect("localhost", "user", "password", "db");     $recordsQuery = "SELECT ARTICLE_NO, USERNAME, ACCESSSTARTS, ARTICLE_NAME, date_format(str_to_date(ACCESSSTARTS, '%d/%m/%Y %k:%i:%s'), '%d %m %Y' ) AS shortDate FROM AUCTIONS WHERE upper(ARTICLE_NAME) LIKE '%?%' ORDER BY str_to_date(ACCESSSTARTS, '%d/%m/%Y %k:%i:%s')" . $max;     if ($getRecords = $con->prepare($recordsQuery)) {         $getRecords->bind_param("s", $searchString);         $getRecords->execute();         $getRecords->bind_result($ARTICLE_NO, $USERNAME, $ACCESSSTARTS, $ARTICLE_NAME, $shortDate);         while ($getRecords->fetch()) {             $result = $con->query($recordsQuery);             $rows = array();             while($row = $result->fetch_assoc()) {                 $rows[] = $row;             }             return $rows;         }     } }   I have tried reading up on this, but I am unsure of what to do. I have read about store result and free result, however these have made no difference when using them. I am unsure at exactly which point this error is being caused, and would like to know why it is being caused, and how to fix it.  Going by my debug statements, the first if loop for countQuery is not even being entered, because of an error in my sql syntax near near '% ? %'. However if I just select * instead of trying to limit based on a LIKE clause, I still get the command out of sync error.


How can I display a string like ]]> in XML ? I tried using normal XML and CDATA, but in XML it doesn't show anything while in CDATA it gives an error.


Why is assumption of Homogeneity of variance required. What are the problems if they are not satisfied


Can True Polymorph be used to transform someone into a shapechanger creature?

The spell clearly says that it does not affect a shapechanger.     Shapechangers are not affected by this spell.   But has nothing about the opposite.  Would that mean that I can change a Goblin into a Doppelganger and that Doppelganger cannot then ever be transformed again with a True Polymorph spell?


In Harry Potter and the Chamber of Secrets, Percy argues with Ron when he catches Ron and Harry in a corridor at night, and tells him, "Five points from Gryffindor." However, in Order of the Phoenix, it states that members of the Inquisitorial Squad, "unlike prefects," can take points from the houses.  Was Percy bluffing? Or is this just a small inconsistency in the books? I prefer to think that Percy just wanted to pretend, since he loved the feeling of power and authority, but I don't know of any other explanation.


adding directory to path environment variable doesn't remain in path

I have been trying to get a program called "passenger-memory-stats" to run as the super user. The program is installed in the following directory: /usr/local/rvm/rubies/ruby-1.9.3-p327/bin/ruby . I know this because i installed phusion passenger using ruby gems:  $ gem env RubyGems Environment:   - RUBYGEMS VERSION: 1.8.24   - RUBY VERSION: 1.9.3 (2012-11-10 patchlevel 327) [x86_64-linux]   - INSTALLATION DIRECTORY: /usr/local/rvm/gems/ruby-1.9.3-p327   - RUBY EXECUTABLE: /usr/local/rvm/rubies/ruby-1.9.3-p327/bin/ruby   - EXECUTABLE DIRECTORY: /usr/local/rvm/gems/ruby-1.9.3-p327/bin   - RUBYGEMS PLATFORMS:     - ruby     - x86_64-linux   - GEM PATHS:      - /usr/local/rvm/gems/ruby-1.9.3-p327      - /usr/local/rvm/gems/ruby-1.9.3-p327@global   - GEM CONFIGURATION:      - :update_sources => true      - :verbose => true      - :benchmark => false      - :backtrace => false      - :bulk_threshold => 1000   - REMOTE SOURCES:      - http://rubygems.org/  /usr/local/rvm/gems/ruby-1.9.3-p327/bin $ ls -l | grep passenger-memory-stats -rwxr-xr-x 1 guarddoggps rvm 416 Dec 14  2012 passenger-memory-stats   So obviously the program is there. I then add it to the root user's PATH environment variable:  $ sudo su export PATH=$PATH:/usr/local/rvm/gems/ruby-1.9.3-p327/bin echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/rvm/gems/ruby-1.9.3-p327/bin   So now it has been added to PATH environment variable. I exit from sudo user to my regular user with sudo privilege and I run the following:  $ sudo passenger-memory-stats sudo: passenger-memory-stats: command not found sudo -E passenger-memory-stats sudo: passenger-memory-stats: command not found   Why does it tell me command is not found? Didn't I add it to my sudo user's path? So I check:   sudo su  echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games   ANd to my surprise, the directory is no longer in the path. What happened?


Databinding an enum property to a ComboBox in WPF

As an example take the following code:  public enum ExampleEnum { FooBar, BarFoo }  public class ExampleClass : INotifyPropertyChanged {     private ExampleEnum example;      public ExampleEnum ExampleProperty      { get { return example; } { /* set and notify */; } } }   I want a to databind the property ExampleProperty to a ComboBox, so that it shows the options "FooBar" and "BarFoo" and works in mode TwoWay. Optimally I want my ComboBox definition to look something like this:  <ComboBox ItemsSource="What goes here?" SelectedItem="{Binding Path=ExampleProperty}" />   Currently I have handlers for the ComboBox.SelectionChanged and ExampleClass.PropertyChanged events installed in my Window where I do the binding manually.  Is there a better or some kind of canonical way? Would you usually use Converters and how would you populate the ComboBox with the right values? I don't even want to get started with i18n right now.  Edit  So one question was answered: How do I populate the ComboBox with the right values.  Retrieve Enum values as a list of strings via an ObjectDataProvider from the static Enum.GetValues method:  <Window.Resources>     <ObjectDataProvider MethodName="GetValues"         ObjectType="{x:Type sys:Enum}"         x:Key="ExampleEnumValues">         <ObjectDataProvider.MethodParameters>             <x:Type TypeName="ExampleEnum" />         </ObjectDataProvider.MethodParameters>     </ObjectDataProvider> </Window.Resources>   This I can use as an ItemsSource for my ComboBox:  <ComboBox ItemsSource="{Binding Source={StaticResource ExampleEnumValues}}"/>


Can I rent a car in Sevilla and drive to Portugal?

At the end of may I'm planning to visit Portugal, but, from Italy, I found that it is cheaper to take a flight to Sevilla and then drive to Portugal.  Since I want to plan all the trip ahead, I'm looking for cars at the Sevilla airport that I can drive to Portugal and leave at Sevilla when the vacation ends.  Are there some companies that allow me to do so? Are there any restrictions to drive between EU countries with a rental car?  INFO: I'm an Italian citizen and I have an Italian driving license, if that matters.  EDIT: the question that you said could have my answer is very different from mine, i want to leave the car exactly where i'll rent it


How would one use filters with the "bulb"-like shape front element lenses?

I am toying with the idea of picking up either the  or the  lens.  These lenses have a built-in petal-shape hood and a "bulb-like" front element. I came across a few reviews about the 14mm f2.8 lens but all of which mentioned the "unusuall" front element and the if so special lens cap that should always be on the lens when not in use. At least  says it is not possible to mount front filters on these lenses. Surely, there is a way...  In situations where I would be normally using these lenses I would want to be able to use ND filters. Is there any way to filters to these type of lenses and if so how and what type?


While I realize there are many topics about CS vs software engineering vs game school programs, I haven't found anything relating to whether pure math degrees (with CS minor and electives) would also be a viable program. By this I mean: Would having a math major, CS minor put one at competitive disadvantage as compared to a pure CS program?  This relates specifically to game engine programming, more on the graphics side.   Background (for those who care): Currently a math major, CS minor at school and looking to land a career doing graphics engine programming. Admittedly, I love math and if at all possible would like to stay my current program as long as it doesn't put me at a competitive disadvantage trying to land a job post-graduation. That being said, I'm strong in the traditional C/C++ languages, strong concurrent programming skills, and currently produce self-made games for iOS. As an employer, how badly is the math major hurting me? Just want to get some advice from people already in the field!


Is it worth buying a 5D Mark I or an EOS 1Ds II today?

I've been taking photographs for a while, and have started to think about moving to full-frame. I'm on a very limited budget, but I currently have a good macro lens and am quite willing to buy something like a EF 50mm f/1.8 to start off with. I could possibly stretch my budget as far as a 70-200 f/4 L or 24-105 f/4 L.  Primarily, I'm interested in taking photos of small wildlife like reptiles, amphibians and insects, but I have a healthy interest in landscapes, birds and street photography.   I currently have an EOS 30D, and I love the way the camera handles, especially with the dual control dials. For this reason, I think shooting with a Rebel would be a significant step down.   However, I have seen 5Ds and occasionally 1Ds Mark IIs on ebay for roughly the same price as an EOS 650D. I'm sure these cameras have better IQ than my 30D, since they are pro-level bodies from around the same time, and full-frame besides. The question is, are these cameras now so old that the image quality from them is a substantial step down from current Rebels?   I realise I'll be giving up continuous shooting speed and some amount of low-light performance, and that I'd also need to get an external flash, but besides these, are there any substantial caveats I need to be aware of before I go ahead and take the plunge?


Why did this character teach the Hogwarts students more than he should have?

During GoF in the Harry Potter series, Profesor Moody       (who is actually Barty Crouch Jr. using Polyjuice Potion)    teaches the kids in his class about unforgivable curses, but then goes into it in detail about them and how they are pronounced, how they work and even how to resist some, like the Imperius curse. He even went as far as saying     "Earn you a one-way ticket to Azkaban. Correct. The Ministry says you are too young to see what these curses do. I say different! You need to know what you're up against. You need to be prepared..."         He also has them practice resisting the imperius curse      "The Imperius curse can be fought, and I’ll be teaching you how, but it takes real strength of character, and not everyone’s got it. Better avoid being hit with it…"   It would seem that teaching students spells to protect themselves from the ambush that you're a major contributor in is not the best plan. That's like arming an enemy country with a missile defense system just before your about to attack them with a missile. And i know that some might say that that he didn't think that Harry would be able to defeat the dark lord anyway but still, why not just teach the 4th year Defense Against the Dark Arts textbook information and be over with it?


Why are so many (all?) Key concepts in thermodynamics derived from a legendre transformation?

Given a function $f(x,y)$, a legendre transform w.r.t. $x$ is $f^*(p,y)=p x - f(x,y) |_{p=\frac {\partial f(x,y)}{\partial x}}$.  E.g. , the various free energies, enthalpy, etc are all legendre transformations of internal energy.  It seems surpising to me that a multitidue (all?) of the important concepts in thermodynamics are derived from legendre transformations, and moreover that the legendre transformation is also the basis of hamiltonian fornalism. Why is this mathematical formalism so fundamental? I would not have been able to know this just based on looking at the definition of the legendre transformation itself.


I've added a repo with the following:  add-apt-repository "deb http://archive.ubuntu.com/ubuntu artful universe"   How would I remove it? I'm using this in a automated script also!


Unable to add time (h:mm:ss) in single column in Excel

I am unable to add time that I have imported in Excel from a csv. The time is in h:mm:ss format. Whenever I attempt to sum the vaules it returns zero. I tried changing the data type to general and number both and also attempted to correct with text-to-column tool with no success. What am I missing? I am open to a solution in VBA and SQL if there is one known.


Change Illustrators "native" SVG resolution

Even if only containing fully vectorized content, SVG files contain a resolution (in pixels). If saving as SVG from Illustrator (CS5), my Illustrator always sets this resolution to 72 dpi. That's what I mean with "native SVG resolution".  This is a problem with our Inkscape-based-lasercutter, that assumes 96 dpi. When I open the Illustrator-SVGs in Inkscape, all artworks are scaled down to 67%. A line that I create in Illustrator with 10 mm will only have 6.7 mm in Inkscape (and the lasercut).  Rescaling the whole artwork by factor 1.3333 will fix that problem, however I'm doing this OFTEN and it is tedious, so being able to rightaway save with 96 dpi would be much more convenient than reopening and rescaling before sending to the lasercutter.  Is there a way to change the "native/assumed" resolution (from the default of 72 dpi), when exporting from Illustrator (save as SVG)?  Unlike  here indicates, changing Effects > Document Raster Effects Settingshas no effect on my SVGs. My SVGs contain no raster-effects whatsoever, only paths.


Why are my new Canon 80D RAW files are unreadable on my computer and on Photoshop CS5?

Has Adobe CS5 stopped supporting new Cameras? I was lucky I shot RAW+JPEG so I was able to atleast have JPEGs quickly. Does that mean Adobe is pushing me to subscribe to Adobe CC?  Is there any free alternative to be able to open these new RAW files into Photoshop and Lightroom?


A random selector can only select one of the nine integers $1,2,3,4,5,6,7,8,9$ and it makes these selections with equal probability.prove that the probability after $n$ selections($n>1$),the product of $n$ numbers selected will be divisible by $10$ is $1-\left(\frac{8}{9}\right)^n-\left(\frac{5}{9}\right)^n+\left(\frac{4}{9}\right)^n$  I do not know how to start with this problem,some hints and suggestions are needed.


I downloaded the Ubuntu 16.04 LTS iso file for Ubuntu desktop and put it on an USB drive after taking that USB drive and booting it leaves me at a screen looking at copyright info and a command prompt, Not sure what to do.The Photo of screen:


Should you put a comma after a question mark in a title in quote marks?

The convention would be to drop a comma after a question mark in normal speech:     “Do you want to come to the movies with us?” Mary asked.   Rather than:     “Do you want to come to the movies with us?”, Mary asked.   But what about when the question mark plays very little to no grammatical function in the scentence, such as in a title.  E.g.      He completed a dissertation titled 'To what extent was Mao responsible for the 1959-61 Great Famine?' for which he studied many secondary and primary sources.   Or     He completed a dissertation titled 'To what extent was Mao responsible for the 1959-61 Great Famine?', for which he studied many secondary and primary sources.   This question is separate from .  Because A) it's not about whether the question mark should go inside the quote marks. That is unambiguously the case because it is part of the title.  And B) it's about a scenario where the question mark has no effect on the meaning of the sentence.      The sentence is:  He completed a dissertation titled [title], for   which he studied many secondary and primary sources.   Whether or not the [title] unit contains a question marks seems less relevant to the meaning of the sentence compared with, for example:      “Do you want to come to the movies with us?” Mary asked.   In the latter structure relaying the question is the primary purpose of the sentence, whereas in the former the question is entirely incidental.


Every function on $\mathbb{R}^n$ that is continuous in each variable separately is Borel measurable.

I'm trying to solve exercise 2.11 from Folland's Real Analysis.    Firstly, how do we show that $f_n$ is Borel measurable on $\mathbb{R} \times \mathbb{R}^k$? I really have no idea how to show this when we have separately Borel measurable functions.  Next, I can't show that $f_n\to f$ pointwise.   For any $(x,y)\in \mathbb{R}\times \mathbb{R}^k$,   $f_n(x,y)=n[f(a_{i+1},y)(x-a_i)-f(a_i,y)(x-a_{i+1})]=n[x[f(a_{i+1},y)-f(a_i,y)]+\frac{1}{n}[f(a_i,y)-f(a_{i+1},y)]]$,   but because of the $n$ outside the bracket, I can't show that this converges to $f$. How can I show this? Also, how can I conclude from this fact that every function on $R^n$ that is continuous in each variable separately is Borel measurable?  I would greatly appreciate any suggestions, hints, or solutions.


How are NFL matchups determined for each season?

During the 2012 NFL Season, the Pittsburgh Steelers and Baltimore Ravens play each other in weeks 11 and 13, two weeks (in both NFL schedule and time) apart. To me, that seems too close for comfort.   I do know that teams play other teams in their division twice. How does the NFL schedule procedure work?


Can we model gravitation as a repulsive force?

This question is actually related to my earlier question ("").  The fact that objects move a lot in the universe and that the universe is expanding, can imply that gravity is a repulsive force that increases with distance.. so the farthest objects repel us more.  This can still explain several existing observations, e.g., why does the apple fall?   Motion is the result of such repulsion. Two objects unlucky enough not to be moving relative to each other get squished due to the repulsion of the rest of the universe  around them. The earth repels the apple less than the stars so it is pushed towards the earth.   Furthermore, it can explain the expanding universe without the need for dark energy.  This could be demonstrated in a thought experiment. If we take a lot of same-charge particles (with small mass) such as electrons and lock them in a large box at a low enough temperature. The mutual repulsion of the particles may cause similar motion as if due to gravitational attraction.   Another experiment would be to measure the slight changes in our weight during day and night when the sun and earth align (if their masses are large enough to detect the feeble change in repulsion).   [EDIT: the question in the original form may not have been clear. It is "can we model".. with a yes/no answer and why (not). If downvoting, please justify.


During this travel ban (COVID) can my wife come visit me in the USA? I know I can visit there but not sure about her coming here

She is dutch and I am a US citizen. Her immigrant visa case is in the process and applied for.


Safari autofill defaults to wrong email address on my card

I'm using Safari on OS X 10.9.3 Mavericks. Anytime I fill in a form that contains an email address field, autofill selects my Evernote email address instead of my real address. This is really annoying as the Evernote address is only used for me to forward mail I want to keep to my Evernote account. I would NEVER enter that on a web form.  First address in my card is "home", second is "work" and the third is "Evernote". I have no idea why autofill would pick this one over the rest. Is it alphabetical?  Is there a way to set which specific email address gets filled in by autofill by default?


How can we improve the experience for non-native speakers on Stack Overflow?

It's obvious to me that there's a trend now on Stack Overflow of relatively low-quality questions from new users who are non-native speakers with low or intermediate fluency in English, or at least claim to be.  It doesn't take a genius to work out that this may be because some of them struggle to read and fully comprehend the various English-language notices and admonitions that Stack Overflow has put in place to try to deter low-quality questions over the years - from welcome pages, to automated content filters displaying terse rejection messages.  I am not saying that such non-native speakers always ask bad questions, of course - far from it! - I am saying that a noticeable number of the low-quality questions, are from such non-native speakers.  What could we do about this particular problem?


Numbering landscape tables does not work properly

I have a problem with numbering landscape tables. The latex code below refers my table to as "Table 0.1". Could you please help me how can I get "Table 1"? Thank you!    \documentclass[preprint,12pt]{elsarticle}     \usepackage{natbib}     \usepackage{amsmath,amssymb}     \usepackage{graphicx}     \usepackage{rotating}     \usepackage[english]{babel}     \usepackage{booktabs,array,dcolumn}     \usepackage{setspace}     \usepackage{verbatim}     \usepackage{longtable}     \usepackage{courier}     \usepackage{color,xcolor}     \usepackage{lscape}     \usepackage{textcomp}      \usepackage{float}     \usepackage{etoolbox}       \begin{document}     \selectlanguage{english}     \subsection{sub}\label{sub1}      In Table~\ref{table:lstab}...      \clearpage     \begin{landscape}     \begin{table}[t]     \label{table:lstab}     \caption{Title}     \begin{tabular}{|c|c|c|c|c|c|c|c|c|c|}     \hline     \hline      A    & B & C & D & E & F  & G & H  & I     &  J     \\     \hline       \end{tabular}      \end{table}         \end{landscape}     \end{document}


Grub command `loopback loop...` does not work on Ubuntu 19.10

During bootup, I enter the grub2 command-line by pressing c on the Grub menu.  When I type the following command...  loopback loop (hd0,gpt2)/ubuntu-19.10-desktop-amd64.iso   ...grub hangs, there is no more output or activity on the terminal, and eventually the laptop fans spin up because the laptop gets hot.  The path (hd0,gpt2)/ubuntu-19.10-desktop-amd64.iso is valid on my system.  I get the same result, regardless of which ISO I use, and I have verified the checksums of the ISOs.  I am experiencing this in Ubuntu 19.10 and did not have this issue in prior Ubuntu releases. The version of grub2-common I have is 2.04-1ubuntu12.  How can I get the loopback grub command to work? (For example, do I need to load specific modules or enter other commands prior to executing loopback?)  (Also, please add a comment if you also experience this issue on 19.10; I'd like to determine if this is specific to my install, or if this is a larger issue?)  (Please note, this question is related to  I have posted, but I beileve they are sufficiently different to warrant a separate post).


What is the difference between the two "worlds" when going thru the day/night wormhole at the altar?

In Pokémon Sun and Moon, when you've finished the game you can switch day and night by going though the wormhole at the altar where you've caught the box legendary. Are there any more differences when going through the wormhole, excluding the day or night difference? For example, the altar of the sunne and altar of the moone switch when going through the portal.


Is there an ArcMap equivalent to the Sieve Tool found in QGIS?     Sieve Tool:  This utility removes raster polygons smaller than a   provided threshold size (in pixels) and replaces them with the pixel   value of the largest neighbor polygon.


I want you to clearly understand that excuses will not do.  I want you to understand clearly that excuses will not do.  My book says that second sentence is correct. What is the logic behind it?


I'm training a classifier for a supervised classification problem. Some of my features interact, how should I normalize these interaction terms?   For example, if x1 and x2 interact, the interaction term is x1*x2. Should the values of x1*x2 be computed before x1 and x2 are normalized, and then normalized. Or should x1*x2 be computed from normalized values of x1 and x2?


Clearing ArrayList causes data from this ArrayList passed to a class constructor to clear as well

I'm facing such a bizarre behavior in Java(Android Studio). What I've been doing is populating an ArrayList of Strings with some data. Then instantiate an object using that ArrayList, the new object is then added to another ArrayList of the object type.  Here is the constructor of the class:      protected ArrayList<String> languages;     public Person(ArrayList<String> languages)     {         this.languages=languages;     }   Then in the Activity, I use two ArrayLists, one called languages and one called Persons. The languages ArrayList is passed to a new object added in Persons.  ArrayList<String> languages=new ArrayList<String>(); ArrayList<Person> Persons=new ArrayList<Person>();  protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main_layout);         .         .         .         .         .         .                 english=(CheckBox)findViewById(R.id.english);                 if(anglais.isChecked())                     languages.add(english.getText().toString());                 Persons.add(new Person(languages));                 Log.i("test: ",Persons.get(0).getLangues().get(0)); // Will show English                 languages.clear(); // Here I clear the languages ArrayList so I can add new languages for another person                 Log.i("test: ",Persons.get(0).getLangues().get(0)); // Produces an exception.             }         });     }   As you can see, I populate languages first, then populate Persons with a new object using languages. In order to add another person with different languages(for example) I must clear the languages ArrayList so I can re-use it.  To test what actually happens, I found out that the first Log will show the added langauge(notice that I am getting the language from Persons, and not languages). However, the second Log will produce an exception stating that the langauges array IN Person class is empty(cleared). What could be causing the clear function not to just clear the languages array, but also the languages array in Person class?


Can I run two 4k (3840x2160) displays at 60hz on a Macbook Pro 13" 2015

I think the title says it all. Can I run two 4k (3840x2160) displays, both at 60hz on a Macbook Pro 13' 2015? I understand they might need to be SST and each connected to a Thunderbolt 2 port. But I cannot get a confirmation whether that setup would work.    says:     Simultaneously supports full native resolution on the built-in display and up to 3840 by 2160 pixels on up to two external displays, both at millions of colors.   …   Support for up to 5120-by-2880 resolution at 60Hz on a single external display (model with AMD Radeon R9 M370X only)   Unfortunately, it does not state at what frequency the two displays can be run.    says:     With OS X Yosemite v10.10.3 and later, most single-stream 4K (3840x2160) > displays are supported at 60Hz operation on the following Mac computers: … MacBook Pro (Retina, 13-inch, Early 2015) and later. MacBook Pro (Retina, 15-inch, Mid 2014) and later   Unfortunately it does not state whether two displays can be run at 3840 by 2160 at 60hz


Why I get null pointer when passing data with Bundle?

I am using Location Fused Provider in my app and I want to send latitude and logitude in Firebase Upstream message from Main activity to the DashBoard Fragment where I have button for upstream message. I have posted similar question, but this is not duplicate. My question is why I get null pointer exception?  This is my method in mainActivity which should pass data:  private void updateUI(){         if(null!=mCurrentLocation){              String lat=String.valueOf(mCurrentLocation.getLatitude());             String lot=String.valueOf(mCurrentLocation.getLongitude());             Bundle bundle=new Bundle();             bundle.putString("KEY_LAT", lat);             bundle.putString("KEY_LNG", lot);             DashboardFragment dashboardFragment=new DashboardFragment();             dashboardFragment.setArguments(bundle);  }   And this is the part of DashBoardFragment where I should put latitude and longitude:  public void getObjectEvent(EventModel data){     String longitude;     longitude=getArguments().getString("KEY_LNG");     Log.d("LONGITUDE", "Longitude is: " + longitude);     Gson data_json = new Gson();     String json=data_json.toJson(data);     FirebaseMessaging fm=FirebaseMessaging.getInstance();     fm.send(new RemoteMessage.Builder(SENDER_ID + "@gcm.googleapis.com")             .setMessageId(UUID.randomUUID().toString())             .addData("action","message")             .addData("data","{\"message\":\"Upstream Message\"}")             .addData("object", json)             .addData("longitude", longitude)             .build());   }   And this is my null pointer:  08-08 14:17:12.755 13165-13165/com.telnet.asp E/AndroidRuntime: FATAL EXCEPTION: main                                                                java.lang.NullPointerException at com.telnet.asp.presentation.view.fragments.DashboardFragment.getObjectEvent(DashboardFragment.java:125) at com.telnet.asp.presentation.view.adapters.DashboardGridAdapter.getDataObject(DashboardGridAdapter.java:145) at com.telnet.asp.presentation.view.adapters.DashboardGridAdapter$3.onClick(DashboardGridAdapter.java:128) at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:157) at android.os.Handler.dispatchMessage(Handler.java) at android.os.Looper.loop(Looper.java) at android.app.ActivityThread.main(ActivityThread.java) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:525) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java) at dalvik.system.NativeStart.main(Native Method)   Could anyone help me? Thanks in advance.


#include<iostream>  using namespace std; class Base {   public:     virtual void show() {       cout << " Amphisoft \n";     } }; class Derived: public Base {   public: void show() {     cout << "E-box\n";   } }; int main(void) {   Base * bp = new Derived; //  cout<<*bp;   bp -> show();   Base br = *bp;//should'nt it return me E-box , why amphisoft   br.show();   return 0; }   Why is the output coming out to Be Ebox Amphisoft . Why not Ebox Ebox? I tried to putting this : Base &br= *bp . And it gives me Ebox Ebox . Here address of the base object is being put equal to address of the new Derived object . But i dont understand what this statement of code is doing : Base br=*bp


AES and DES - reusing the same round keys

Both DES and AES use key expansion to generate the round keys (for Feistel network or for the AddRoundKey operation). Each round uses a different key. Why do we need that? Why we cannot use the same key in each round?


What will happen if client call Apache server by IP and there are two SNI virtual hosts

We have a Apache 2.4 web server with a couple of virtual hosts with different certificates.  I have  set up SNI name based virtualhosts : ap.mmm.com and ac.mmm.com, it's working great. All on same IP (172.12.12.1) and same 443 port. The question is : what will happen if client will use IP and not server name to get to the Apache server : I.e will use 172.12.12.1:443 instead of ap.mmm.com ?


Free Compositing video tutorials in blender

Where can I get indepth tutorials about compositing in blender for Free? Any channel I can get such videos about compositing in blender?


Help with telescoping sum $\sum_{i=3}^n \frac{1}{i(i+3)} $

How can I use the telescoping technique to compute the following sum? I'm having issues getting started. I know the basic steps but I don't know how to perform them. I know I have to separate the fraction into A and B. After that I have to perform the sum but I'm not sure what comes next.   $$\sum_{i=3}^n \frac{1}{i(i+3)} $$  Thanks for any help!


c# working with image data, use arrays or lists?

I am starting c#, and from what i read lists<> are most often preffered. But i kind use to; to think in arrays from my PLC coding past. I work a lot with blackwhite raw instrument image data. Which i currently put in a color array ea      BWcolor[x,y] = 255;  it could also be done with lists in which the same point could be defined as element nr:    x+stride * y  I wonder should i convert image handling to use list data or keep thinking in arrays. Because i read about that arrays should not be used in most cases. And that lists are faster?; or are lists in general better since lists have more buildin functions ? (like inserting elements). And if thats so it would only be handy to code so if my functions would depend on their functions.  I not realy get it why a lists are prefered when thinking in 2dimensional spaces, but if it is beneficial i would better start converting my code to use lists.


Why doesn't work the calling to a method in JAVA (Single example)

I'm working with LeapMotion. I have this code in my main class:  public void onFrame(Controller controller) {     Frame frame = controller.frame();     GestoPistola gesto;      if (!frame.hands().isEmpty())      {         System.out.println("ENTER");         gesto.reconocer(frame);     } … }   And then, this is the class GestoPistola, which is the one that has to make all the job.      public class GestoPistola {        public enum ESTADO{            DESCARGADA, CARGADA        }         ESTADO _estado;         public void GestoPistola(){            _estado = ESTADO.DESCARGADA;        }         public void reconocer(Frame f)        {            System.out.println("LET'S START");             if (!f.hands().isEmpty()) {                System.out.println("Hay mano");                Hand hand = f.hands().get(0);                FingerList fingers = hand.fingers();                 switch(_estado)                {                      …                }            }         }    }   So, the consol shows "ENTER", but never "LET'START".  I know it's a really simple question, but I'm not such an expert with JAVA.  Hope someone can help me!


Force file extension to open with specific app (Extensions like .exe, .jpg, .mp4...)

I have already read the question about  but this is not what I want, I want to be able to click on the file in Dash or in Nautilus and be able to open it with the specified app.  For example I have this case right now:  When I click on an EXE file it does not get executed by Wine, instead I get the following:    If I try to look for Wine in the Open With context menu option it is there. I am fine executing it from there the first time, but then the following times Wine does not appears selected in the main Context menu:    I then went to Properties to the Open With Tab to look for Wine. It was not in the Default apps nor was it in the Recommended ones when I clicked and search on Show other applications    This is not limited to EXE extensions. It also has happened with MKV files, MP4 files, JPG, PNG, MP3 and even SVG and CSS. So instead of trying to find a way of solving it for one, I want a way that can be done to any type of extension that can:   Make the app the default of that extension Appear on the context menu in Nautilus when I right click on the file Appears on the "Open With" tab on the Property window of the file Correctly executes the specified app when I click on the file with Dash   This might sound like it should be common sense for an app to execute the file but it does not always work like that. So for the cases where it actually does not work, how to fix it. A reset of the extension?, An update of the files that can open said extension?, an addition of the app via a command line or GUI tool?


How can I remove the Lubuntu packages after installing ubuntu-desktop on top of Lubuntu?

On this machine, I installed Lubuntu 12.04 and then installed the ubuntu-desktop package. Now there is some Lubuntu software, such as the Lubuntu Software Center, Xscreensaver, and Abiword, that needs to be removed.   There are plenty of scripts online, like , that describe how to get back to a pure Ubuntu desktop (after installing the lubuntu-desktop package) by removing all the Lubuntu packages, that is, the packages that lubuntu-desktop depends on. Can I use that script to remove the old Lubuntu packages and fully migrate to pure Ubuntu? I am worried that the script may remove some packages, like libbluray, that Ubuntu needs.


Lets say you have an equation with the following form. $$(a+ib)^{c+id}$$  How do you go about doing it? I am very familiar with De Moivre's Theorem where d is zero and have that all set. I am unfamiliar with d being real not equal to zero.  Any additional information would be very helpful.


why is some of my swap space being used, when I still have unused RAM?

More of a curiosity than a problem;  and, I admit, something of an embarassingly basic question:  I've noticed that on many occasions, on my Linux machine I will have ~500MB of swap space in use, even though I have ~600MB of unused RAM.  My naive high-level understanding was, swap space doesn't kick in until RAM is exhausted.  I went further and made the assumption that this situation must be the doing of the Linux kernel, because a user process that requests memory, does so only logically, and has no notion of whether that memory is physically backed by RAM or the swap space.  Which leads to the question, why would the kernel preemptively use the swap space?  Is this part of some performance tuning algorithm?  Is it swapping out to disk parts of memory that it deems least likely to be accessed (an LRU scheme, perhaps)?  If so, wouldn't it just make sense to leave everything in RAM, and only when nearing exhaustion, then and only then swap the LRU portions from RAM to the swap space?   I should clarify, my linux server has 2GB of RAM and 2GB of swap space.


Would this proof work?   Let $N$ be a nilpotent in a commutative ring and let $X$ be a unit.   Let $Y$ be an element in the ring.   Proof by contradiction:   Assume  $$Y(X+N) \neq 1$$  Then   $$YX + YN \neq 1 $$  Then  $$YXN^{n-1} \neq N^{n-1} $$  A contradiction since since $Y$ can be the inverse of $X$ and thus the equation can hold above.


Boot into Ubuntu from Windows and into Windows from Ubuntu

I'd like to be able to boot into Windows from Ubuntu and into Ubuntu from Windows with grub.  Can I edit my /boot/grub/grub.cfg where there's the following:  # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub #  ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then   set have_grubenv=true   load_env fi set default="3"   and only change from time to time the set default = "x" where x is the operating system on the grub list I want to boot on?  Is this going to work?


How can I prevent iTunes from auto starting when I plug in an iOS device?

i know we already have topics about it, but i did not found my solution.  So i don't want to start iTunes, when i plug in iDevices. We have like 300 iPads, and i am using the configurator. iTunes still starting automatically, even when the Configurator is running.  I really don't want to turn off this settings under the iPad summary screen one by one. I have already turned off the autosync.


How many ways can you paint a regular Decagon with q colors? Solve with Burnside's lemma

How many ways can you paint a regular Decagon with q colors? I need to solve it with Burnside's lemma. So far I managed to find only 2 symmetries, the identity, and this one. I believe I miss the method, can someone solve, and try to explain how did he solve it?


Is it possible to number tex files? I'm avoiding it now but, I would like to order a list of files (chapters in a book) so that each chapter is easy to find. Will this cause a problem? I have in mind:  aaa_introduction 001_chapter_one.tex 002_chapter_two.tex bbb_backmatter.tex etc.   Mike


How to change programmatically exposed filters in views

I have a page view with exposed filters. One of the filters is term vocabulary, and that's dropdown list, user can select only one category (term).   I want to set programmatically one term from dropdown list when I came from specific URL. I tried with views_query_alter where $category is tid.    $set_exposed_input  = array();  $set_exposed_input['field_category_tid'] = $category;   if ($set_exposed_input) {     $view->set_exposed_input($set_exposed_input);  }


I wanted to align the four images in a grid of 2x2, but the images are getting arranged vertically. I'm working on a template of IEEE format. This is the code that I'm working on:  \begin{figure}[!tbp] \centering  \begin{subfigure}{0.25\textwidth} \includegraphics[width=0.7\linewidth,height=5cm,center]{MobileApp/Menu.png} \caption{Menu} \label{fig:menu} \end{subfigure}  \begin{subfigure}{0.25\textwidth} \includegraphics[width=0.7\linewidth,height=5cm,center]{MobileApp/Cart.png} \caption{Cart} \label{fig:cart} \end{subfigure}  \begin{subfigure}{0.25\textwidth} \includegraphics[width=0.7\linewidth,height=5cm,center]{MobileApp/Address.png} \caption{Address selection} \label{fig:address} \end{subfigure}  \begin{subfigure}{0.25\textwidth} \includegraphics[width=0.7\linewidth,height=5cm,center]{MobileApp/Payment.png} \caption{Payment screen} \label{fig:payment} \end{subfigure}  \caption{Main screens of the application} \label{fig:main} \end{figure}   Any suggestions as to what needs to be done to get them arranged in a grid?


I have edited this question to make myself clear. My question was.  If we define  String a  we can define characters as a[],  but if we define String ^ a  a[] cant be defined.   So why a[] is not defined if both are strings.


sed with multiple expression for in-place argument

I am trying to replace multiple words in a file by using   sed -i #expression1 #expression2   file  Something  123 item1 Something  456 item2 Something  768 item3 Something  353 item4   Output (Desired)  anything  123 stuff1 anything  456 stuff2 anything  768 stuff3 anything  353 stuff4   Try-outs  I can get the following output by using sed -i two times.   sed -i 's/Some/any/g' file  sed -i 's/item/stuff/g' file   Can I have any possible way of making this as a single in-place command like   sed -i 's/Some/any/g' -i 's/item/stuff/g' file   When I tried the above code it takes s/item/stuff/g as a file and tries working on it.


General formula of $\sum_{n\ge1}{\binom{2n}{n}^{-k}}$.

If $k=1$, we have \begin{align} \sum_{n\ge1}\frac{1}{\binom{2n}{n}}&=\frac12\sum_{n\ge1}n\mathrm{B}(n,n)\\ &=\frac12\int _{0}^{1}\sum_{n\ge1}n(t-t^2)^{{n-1}}{\mathrm  d}t\\ &=\frac12\int _{0}^{1}\frac{1}{(t-t^2-1)^2}{\mathrm  d}t\\ &=\frac13+\frac{2\sqrt3\pi}{27} \end{align} I wonder if there exists a general formula of $\sum_{n\ge1}{\binom{2n}{n}^{-k}}$ with $k\in\Bbb N^*$. This may involve some ${}_pF_q$ functions.


In the Mail application, when I choose the option "see more from " the app unfolds the replied messages in different colors as quoted texts. How can we undo the unfolding and hide the quoted text? It is so messy right now.  Please see the image below for the part that I want to hide.


Realtek RTL8723be Wifi and Bluetooth 14.04

I just installed the OS on my laptop and at first wifi didn't work. After connecting to ethernet and updating everything, the wifi is working. But it disconnects here and there and requires me to reload the service or reboot. The bluetooth on the card does not work at all. It is seen and hciconfig shows an address for it. However, I cannot find bluetooth devices with it. I have seen a lot of different posts with this card but most of them are older. Where can I go from here.


Stopping all automatic updates Windows 10

We've upgraded some machines to Windows 10 and realized there were some updates which updated as required. However, I realized there was no option available to stop the download similar to that on Windows 7 and 8.1. The only way I could stop the download was to stop the Windows Update service.  My question is does anyone know of a way to stop auto updates or is stopping the service is the only solution?


Setting default Asp.Net Session memory consumption?

Some while ago I found a web page explaining the default size of a session was 2048 kb, the minimum was 1 kb.  How can this be adjusted? And if some one has links regarding the subject I would be a happy camper :)  Sorry not for mentioning the IIS, but it is 7.0  Cheers


Optimal coil specification connected to a 160W audio amplifier to produce an "intense" varying magnetic field

Disclaimer: I’m computer scientist I would like to generate an "intense" varying magnetic field by connecting a coil to a max 160W audio amplifier. The theoretical output frequency range is 20Hz to 20kHz. I plan to only output sinusoidal signals in the range 500Hz to 5000Hz. The audio amplifier I have to do that is a 4Ω SMSL SA 98E 2x160W , . I would like to know what should be the optimal inductance of the coil I should use and the wire thickness. I have so far tried a 0.5mH coil with 0.5mm wire, but the coil heats which indicates that the wire is too thin. 0.5mH is ~4.4Ω at 1kHz. What is the most unclear to me is the 4Ω impedance required by the amplifier. At what frequency should it be 4Ω ? I could not find a clarification on that with google. But I did find plenty of warnings that it can harm the amplifier if the impedance of the HP is too low. Since I don’t want harm my amplifier, I ask the experts here if the 4Ω impedance should be at 1kHz or 20kHz. In the later case the inductance of my coil should indeed be much lower. Edit 1: as asked by StackExchange I must clarify why this question is different from . The titles are very close, but I initially badly formulated my question which ended on a different topic (measuring inductance). Tony Stewart Sunnyskyguy EE75 did provide a precise answer to the question in the title but I was unsure if it was safe for my amplifier. This question is now more on topic and ask about the risk for my amplifier to use a low inductance. I apologise for the inconvenience.


Using permutations to find the determinant.

I came across the following problem  Let matrix A be a $n\times n$ square matrix such that $a_{ij}$ = max{ i , j }. Prove that det(A) = $(-1)^{n-1}n$  I have read the post  and understood all the answers adressing the same problem. I just wanted to see an alternative method which does not use row subtractions. As, the determinant fromulla $n(-1)^{n-1}$ is reminiscent of $\frac{d}{dx}(x^{n})$ Is there some way we could use differentiation of determinant technique? How would it be if one goes by the formulla of determinant in terms of permutations?


So I've been highly interested in D&D through watching streams of it but unfortunately no one plays D&D anywhere close to me. I don't have a clue on how to make characters etc. So if anyone could help me then that'd be greatly appreciated.


I have the array of the arrays of char. I need to convert it into an array of int. How can I do that? I know we can convert char* to int as follows:  char *i = "123"; std::stringstream ss; ss << i; int ii; ss >> ii; std::cout << ii << std::endl; //prints 123   But how can I convert the array of such an arrays into an array of integers?


Prove that the nilradical of $\mathbb{Z}_m$  is the set $\{0\}$ if and only if $m$ is not divided by any square of a prime number.   Here is my attemt for one part of the problem:  Let $N(\mathbb{Z}_m)=\{0\}$ and suppose that there exists a prime $p$ such that $p^2|m$.  Then $m=sp^2$. I took the element $[ps]\in \mathbb{Z}_m$ for which we have that $[ps] \neq [0]$ and $ps<m$.  We see that $[ps]^2=0$ thus $N(\mathbb{Z}_m) \neq \{0\}$ deriving a contradiction.  Is this part of the proof correct?  Can someone help me to prove the other part  of the statement?  Thank you in advance!


photoelectric emission with multiple photons

Is it possible for two or more photons to collide simultaneously with one electron, resulting in the emission of that electron from the metal surface? I searched for two photon absorption and found that an atom or molecule can absorb two photons if the sum of their energies is greater than the work function, but I want to know whether it is possible for two or more photons to interact with a single electron and cause its emission?


Is there a clean way to exit a .net service?

I am speaking specifically of a service as opposed to an application.  Environment.Exit(0) and Stop() both give a message box saying they were stopped unexpectedly (even if there's no actual error given).  The goal is to start a service on startup (it must be a service, not an app), have it perform a small task, and then exit. It should simply exit cleanly without a message box.


Is this convergent or divergent: $\sum _{n=1}^{\infty }\:\frac{2n^2}{5n^2+2n+1}$?

Is this convergent or divergent? if convergent, find the sum. If divergent explain why.  $$\sum _{n=1}^{\infty }\:\frac{2n^2}{5n^2+2n+1}$$  I want to use the divergent test which is $\mathrm{If\:}\lim _{n\to \infty }a_n\ne 0\mathrm{\:then\:}\sum a_n\mathrm{\:diverges}$   $\frac{2n^2}{5n^2+2n+1}$  I would assume to take out the largest $n$ in both the top and bottom   $\lim _{n\to \infty }\left(\frac{n^2}{n^2}\cdot \frac{2}{5+\frac{2}{n}+\frac{1}{n^2}}\right)\:$  having the $n^2$ cancel  $\lim _{n\to \infty }\frac{2}{5+\frac{2}{n}+\frac{1}{n^2}}$ after taking the limit  $\frac{2}{5+0+0}$  so $\frac{2}{5}$$\ne $ $\:0\:$ so it's divergent?


How to disable dark edge outlines in sculpt mode ?


How to manage and restore a modern iPhone or iDevice on ubuntu with iTunes

This question—how to install iTunes on ubuntu—has been asked many times before on this site, but the answers are all outdated and involve Wine or some other tool that no longer works for the most recent version of iTunes. Put simply, I need to regularly back up and occasionally restore the firmware on an iPhone 6.   I cannot:   dual boot Windows—for some reason installing one OS makes the other unbootable & after days of headache & dozens of reinstalls I’ve decided to just leave Ubuntu be & not try to preserve Windows. Plus “just use Windows” is not really a solution on an Ubuntu forum. use libimobiledevice-dev. libimobiledevice-dev doesn’t let you manage iOS updates or sync music anymore. Buy another phone. This one should be obvious but for some reason some asshat always comments “too bad lmao shouldntve bought an iphone ;P”.


What is the main difference between static class & Singleton class

here is two piece of class code one is for Singleton and other one is for static class. i like to understand in programming when one should use static class and when one should use Singleton class?  both are used to hold the global object as a result we can access those data from any where of the program when it is running. scope is broad for both....the life time of application.  1) i really do not find any article which can guide me when i should use static class and when Singleton class should be good choice. i have seen people manage db connection using Singleton class.  2) what is the main difference between Singleton class & static class ?  public sealed class Singleton {     private static Singleton instance = null;     private static readonly object padlock = new object();      Singleton()     {     }      public static Singleton Instance     {         get         {             lock (padlock)             {                 if (instance == null)                 {                     instance = new Singleton();                 }                 return instance;             }         }     } }   public static class TestStatic //: ITestSingleton     {         public static void doAction(string args)         {             Console.WriteLine("Test Static :: " + args);         }     }


I read that the space of quantum states, i.e. the space of density operators $\mathcal{S}_n = \{ \rho \in H_n : \rho \geq 0, \, \, Tr[\rho]=1\}$ is a smooth manifold of dimension $n^2-1$, without further explanation. Could anyone help me understand why this is the case? Here $H_n$ denotes the space of hermitian matrices: $H_n = \{ A \in \mathbb{C}^{n \times n} : \, A^* =A  \}$, and $\rho \geq 0$ means that the matrix $\rho$ is positive semi-definite.


Why can't the outcome of a QM measurement be calculated a-priori?

Quantum Mechanics is very successful in determining the overall statistical distribution of many measurements of the same process.  On the other hand, it is completely clueless in determining the outcome of a single measurement. It can only describe it as having a "random" outcome within the predicted distribution.  Where does this randomness come from? Has physics "given up" on the existence of microscopic physical laws by saying that single measurements are not bound to a physical law?  As a side note: repeating the same measurement over and over with the same apparatus makes the successive measurements non-independent, statistically speaking. There could be a hidden "stateful" mechanism influencing the results. Has any study of fundamental QM features been performed taking this into account? What was the outcome?    Edit: since 2 out of 3 questions seem to me not to answer my original question, maybe a clarification on the question itself will improve the quality of the page :-)  The question is about why single measurements have the values they have. Out of the, say, 1000 measure that make a successful QM experiment, why do the single measurements happen in that particular order? Why does the wave function collapse to a specific eigenvalue and not another? It's undeniable that this collapse (or projection) happens. Is this random? What is the source of this randomness?  In other words: what is the mechanism of choice?    Edit 2: More in particular you can refer to chapter 29 of "The road to reality" by Penrose, and with special interest page 809 where the Everett interpretation is discussed - including why it is, if not wrong, quite incomplete.


Why is the well ordering principle counter-intuitive?

I read  that while 'The Axiom of Choice agrees with the intuition of most mathematicians; the Well Ordering Principle is contrary to the intuition of most mathematicians'. I don't understand why this is so. According to Wikipedia, 'the well-ordering principle states that every non-empty set of positive integers contains a least element'. This is quite a straightforward definition. Is it the way you derive the equivalence of the Axiom of Choice and well ordering principle that makes it counter-intuitive or the definition of the least element?


Consider the set $S= \{\frac{p}{2^n} : p,n \in \mathbb{Z}\}$. Is it dense in $\mathbb{R}$ ?? To me intuitively it seems to be dense but I cannot come up with any analytic proof or disprove .


I have a very simple situation that I can't seem to resolve. I want to centre the text vertically to the FontAwesome icon. But I can't for the life of me figure out why it's not centering.  I have tried other answers but none seen to utilise the :before CSS definition which is a very accepted way to implement icons.  Here's my code:   #rk-lesson-menu {     display: inline-block;     width: 100px;     height: 60px;     float: right;     text-align: center;     border-left: 1px solid #DDD;     line-height: 60px;     vertical-align: middle;     text-decoration:none } #rk-lesson-menu:before {     font: 28px/60px fontawesome;     content: "\f0c9";     padding-right: 3px; } <link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet"/> MENU