After installing apps via apt-get install -app name-. Where does the files get copied to? Are the copied to just one location or multiple locations? And if so how do I find this out?  Here's an example:

I want to know where I can find my installed application when I installed it on Ubuntu using package manager.  I installed RabbitMQ and ran locate rabbitmq which gave me following result:  /home/anupamg/.m2/repository/com/rabbitmq /home/anupamg/.m2/repository/com/rabbitmq/amqp-client /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2 /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/_maven.repositories /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/amqp-client-1.7.2.jar /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/amqp-client-1.7.2.jar.lastUpdated /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/amqp-client-1.7.2.jar.sha1 /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/amqp-client-1.7.2.pom /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/amqp-client-1.7.2.pom.lastUpdated /home/anupamg/.m2/repository/com/rabbitmq/amqp-client/1.7.2/amqp-client-1.7.2.pom.sha1 /home/anupamg/Downloads/rabbitmq-server-generic-unix-2.4.0.tar.gz


In episode 7 season 5 of Through the Wormhole, they say that gravity could just be a manifestation of the strong nuclear force and that the force carrier are a pair of Gluons. Is this valid in anyway?

What makes the two 'color-neutral' gluons $(r\bar r−b\bar b)/\sqrt2$ and $(r\bar r+b\bar b −2g\bar g )/\sqrt6$ different from the pure $r\bar r +b\bar b +g\bar g $ ?  Why don't they result in long range (photon-like) interactions?


I created a DialogFragment. The Dialog got a EditText and I call it from the dialog xml. But there is the error: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference  New in this code:      AlertDialog alertDialog; AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());   and  final EditText editText = (EditText) alertDialog.findViewById(R.id.editTextPasswordDeveloper);   My Code:  public class DeveloperLoginDialogFragment extends DialogFragment {  EditText editText;  @Override public Dialog onCreateDialog(Bundle savedInstanceState) {      final LayoutInflater inflaterDialog = getActivity().getLayoutInflater();      AlertDialog alertDialog;     AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());      alertDialog = builder.create();     // final AlertDialog alertDialog = new AlertDialog.Builder(getActivity());     builder.setCancelable(false);     builder.setView(inflaterDialog.inflate(R.layout.alertdialog_developer, null));     final EditText editText = (EditText) alertDialog.findViewById(R.id.editTextPasswordDeveloper);     builder.setTitle("Entwickler-Login");     builder.setMessage("Um dich als Entwickler zu verifizieren, gib den Entwickler-Code bitte unten ein.");     builder.setPositiveButton("Verifizieren", new DialogInterface.OnClickListener() {         @Override         public void onClick(DialogInterface dialog, int which) {             if(editText.getText().toString().equals("7846")) {                 dialog.dismiss();                 Toast.makeText(getActivity().getApplicationContext(),"Erfolgreich verifiziert!", Toast.LENGTH_LONG).show();             }         }     });     builder.setNegativeButton("Abbrechen", new DialogInterface.OnClickListener() {         @Override         public void onClick(DialogInterface dialog, int which) {             Intent intent = new Intent(getActivity(), MainActivity.class);             startActivity(intent);         }     });     return builder.create(); }   }

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


I have done a research project for a vocational masters. During then, there was a major disruption in the teaching department which affected the supervision process. However, I was already having another Masters degree and was in my last stage of a PhD degree program as well. So I planned, conducted, analysed and wrote my research thesis without any supervision. The only supervision I can think of is reading the completed thesis by my supervisor (which was assigned to me in later stage of the project, who  managed to give very minor comments which I feel was not significant at all as I did not have to change things except some paraphrasing and proofreading as I'm not a native English speaker.   Now I'm in the process of publishing a paper from that research and wondering if I can publish it as a single author paper? I normally do not mind to involve my supervisor or any team member who worked with me in a study as long as I believe there was some how a considerable contribution, but in this time, my work is asking me to publish a single author paper as part of the requirement for promotion so there is another reason to push me more critical for whom should be involved. So do you think it is okey based on the above situation to proceed in publishing the work by my own as a single author paper?   Thank you in advance

I understand that in a lot of big-lab fields it is common for the principal investigator to append their name to a paper even if they did not write the paper, design the experiment, or collect data since they spend energy securing funding, and managing the whole lab. What about for small labs?  What are the requirements for a supervisor to be included as an author on a paper, as opposed to just appearing in the acknowledgements? If you are working on your own projects independently of your supervisor, but using funding provided by your supervisor (how does this change when the funding provides resources versus just your salary), are you suppose to add them as authors or just acknowledge the source of funding?


How to input a number from 0 to 1000 and have python return a string that is always 4 characters long. for example: input 10 python should return 0010

What is a Pythonic way to pad a numeric string with zeroes to the left, i.e. so the numeric string has a specific length?


Whenever I try to edit something on my profile the changes are denied and this message shows:     Oops! There was a problem updating your profile: This email address is already registered. If it belongs to you, log in above or visit our account recovery page to get access to this account.   I'm trying to edit my profile so I'm already logged in. I don't know how to fix it to be able to update my profile information correctly.

I am unable to update my user profile settings on Stack Overflow as I receive the following warning:     Oops! There was a problem updating your profile:   This email address is already registered. If it belongs to you, log in above or visit our account recovery page to get access to this account.   I have read through some of the similar questions about having to merge accounts but I only appear to have one account. I tried logging in with Facebook and standard email but both appear to link to the same user number.


I'm a neophyte user trying to set my system up to program in PhP via Ubuntu. I have a cd with version 12.10 and would like to know how to upgrade after install and install packages for PHP... I'm guessing is what I need to do .... -- sooo I see that my version is no longer supported, how do I get the latest version

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


A permutation can't be both even and Odd. How?? Is their any proof??  Kindly tell me.!  Thanks beforehand

How we can show every permutation is either even or odd,but not both......I can't arrive at a proof for this ..... Can anybody give me the proof...  Thanks in advance...


Are they have the same meaning? I'm not confident/sure they are same.  Ex.  "We have an active shooter," a different woman says in another 911 call. "We have a child down."  "We have got an active shooter," a different woman says in another 911 call. "We have got a child down."  I copied it from

I don't know what is the difference between using "I have got" and "I have" For example:      He's got broad shoulders.    Is it possible to say:      He has broad shoulders.    If yes, so what is the difference?


I am facing undefined reference issue while creating executable.  Error:  ../build/kl/Release/test/maker/guibase.o: In function `decodeAddrList': tree234.c:(.text+0xc): undefined reference to `ptritclStubsPtr' tree234.c:(.text+0x20): undefined reference to `ptritclStubsPtr' tree234.c:(.text+0x12c): undefined reference to `ptritclStubsPtr' tree234.c:(.text+0x140): undefined reference to `ptritclStubsPtr'   Build Command:-  pkgs/gcc/v4.8.3/bin/gcc -L/usr/X11R6/lib -O2 -DUSE_FLEX -Wall -Wno-char-subscripts -fPIC -DLINUX -DG_DISABLE_CONST_RETURNS -fno-strict-aliasing -o ../build/kl/Release/test/bin/pure.exe -L../build/kl/Release/test/modules ../build/kl/Release/test/maker/constrfunc.TCL.o ../../build/kl/Release/test/maker/pvdbprocs.TCL.o .. ../build/kl/Release/test/maker/maker/memmaker.TCL.o .. ../build/kl/Release/test/maker/modules/libdenbase.a .. ../build/kl/Release/test/maker/guibase.o  -lcdnviptcl8.4 -ldenbase -lglib-2.0 -ldenbase -lX11 -ldl -lm -lviputil -lvippli -lcdsCommonMT_sh -lpthread  -L/home/dlb/extlibs/arm/lib    I have that symbol defined in the library 'libcdnviptcl8.4' at path '/home/dlb/extlibs/arm/lib' . But still facing the same issue.  Symbol :-  readelf -s libcdnviptcl8.4.so | grep ptritclStubsPtr   636: 00000000000d8068     8 OBJECT  GLOBAL DEFAULT   24 itclStubsPtr 1240: 00000000000d8068     8 OBJECT  GLOBAL DEFAULT   24 ptritclStubsPtr   Am I missing some thing here? Please help  Quote from comment by OP: "Due to some privacy issues...I am renaming the symbols.. It was edited by me... It was typo...I just corrected it...:)" I.e. the identifiers in the error message and the grep line and the output of the grep line have been manually altered.

Why does the order in which libraries are linked sometimes cause errors in GCC?


Question : Is the following true for any $m\in\mathbb N$?   $$\begin{align}\sum_{k=1}^{m-1}\frac{1}{\sin^2\frac{k\pi}{m}}=\frac{m^2-1}{3}\qquad(\star)\end{align}$$   Motivation : I reached $(\star)$ by using computer. It seems true, but I can't prove it. Can anyone help?  By the way, I've been able to prove $\sum_{n=1}^{\infty}\frac{1}{n^2}=\frac{{\pi}^2}{6}$ by using $(\star)$.  Proof : Let  $$f(x)=\frac{1}{\sin^2x}-\frac{1}{x^2}=\frac{(x-\sin x)(x+\sin x)}{x^2\sin^2 x}.$$ We know that $f(x)\gt0$ if $0\lt x\le {\pi}/{2}$, and that $\lim_{x\to 0}f(x)=1/3$. Hence, letting $f(0)=1/3$, we know that $f(x)$ is continuous and positive at $x=0$. Hence, since $f(x)\ (0\le x\le {\pi}/2)$ is bounded, there exists a constant $C$ such that $0\lt f(x)\lt C$. Hence, substituting $x={(k\pi)}/{(2n+1)}$ for this, we get $$0\lt \frac{1}{\frac{2n+1}{{\pi}^2}\sin^2\frac{k\pi}{2n+1}}-\frac{1}{k^2}\lt\frac{{\pi}^2C}{(2n+1)^2}.$$ Then, the sum of these from $1$ to $n$ satisfies  $$0\lt\frac{{\pi}^2\cdot 2n(n+1)}{(2n+1)^2\cdot 3}-\sum_{k=1}^{n}\frac{1}{k^2}\lt\frac{{\pi}^2Cn}{(2n+1)^2}.$$ Here, we used $(\star)$. Then, considering $n\to\infty$ leads what we desired.


Does I ate food a lot mean ambiguously?  I ate a lot of food. I made a lot of chewing, biting or the other action on food.

I eat too much = I eat food too much I eat too much food = I eat too much food  ‘Too much’ in the first sentence modifies a verb. ‘Too much’ in the second sentence modifies a noun. They have certainly different meanings, but how are ‘I eat too much’ and ‘I eat too much food’ able to be interchanged?


I have this statement and I'm trying to remove the first character and replace it with a blank string but for some reason this returns false. It seems like it's just setting it equal then asking if it's equal to me.  public class Test1 {     public static void main(String[] args)     {         String aString = "123";         String sub = Character.toString(aString.charAt(0));         System.out.println(sub == Character.toString(aString.charAt(0)));     } }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I am new to generics and I am trying out to make a linked list.  Here is the Code for Node_ class.  public class Node_<T> {      private int index;     private T data;     private Node_<T> next;     public Node_() {     }      public Node_(T data, int index) {         this.data = data;         this.index = index;         next = null;     }      public void set(T data, int index) {         this.data = data;         this.index = index;         this.next= null;     }      public void display() {         System.out.println(this.data.toString());     }      public void setindex(int index) {         this.index = index;     }      public void setData(T data) {         this.data = data;     }      public Node_<T> getNext() {         return next;     }      public boolean hasNext() {         if (next != null) return true;         else return false;     }      public int getIndex() {         return this.index;     } }   and linked list class.  public class LinkList<T> {         private int total = 0;     private Node_<T> start;     private Node_<T> end;     private Node_<T> ptr;      public LinkList() {     }          public LinkList(T data) {         start = new Node_<T>(data, 0);         end = start;         ptr = start;         total++;     }      public void add(T data) {         if (start == null) {             start = new Node_<T>(data, 0);             end = start;             ptr = start;             total++;         } else {             end.set((T) data,(int) total);             total++;             end = end.getNext();         }     }       public void displayAt(int index) {         if (start != null) {             ptr = start;             do {                 if (ptr.getIndex() == index)                     ptr.display();             } while (ptr.hasNext());         }          else             System.out.println("No Element found");     }      public void displayAll() {         if (start != null) {             ptr = start;             do {                 ptr.display();             } while (ptr.hasNext());         }          else             System.out.println("No Element Present");     } }   The following code in Main class  public class Main {     public static void main(String[] args) {             LinkList<Integer> list = new LinkList<Integer>(25);         list.displayAll();         for (int i = 0; i < 11; i++) {             list.add((Integer) i);         }         list.displayAll();     }  }   I am getting the following error and i cant figure out the problem.  25 Exception in thread "main" java.lang.NullPointerException at LinkList.add(LinkList.java:26) at Main.main(Main.java:8)   Any suggestion where am I going wrong.

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


Hi I am Libyan I have US IR1 visa to the USA . family of six members   adults and 4 kids   how much Maximum money as immigrant family can carry to USA ? please advise

I was wondering if someone knows the legal limit of cash money allowed per adult tourist when entering the US, especially from the UK.  The reason is that I would like to get the best conversion rate and buy some dollars (selling my GBP) at the UK cambios/exchange offices so that my bank fees and other charges can be avoided. Therefore, taking the legal limit of cash will help me to make the most out from the currency conversion mishapps.  Any idea on those numbers?


I am using C and I am trying to write a small game. But I need to read the input whenever the player tabs on a key (say s), and the program does something, without pressing the enter.  I have seen many posts answering this, but they all use getchar() or getch() from curses or conio.h in Windows. But that's not what I want. The result can definitely done because of 2 examples:   vim when the user tabs on the :, it will immediately turns into the command mode to let you type in the commands. the readcommand in bash, whose -n${number_you_want} parameter can limit the chars it reads without enter.   But I wonder how they can do this even I already have the source of the functions in the examples. I still can't figure out how they do this. The source code of vim's  from getchar.c and the read command from bash source .  Can anyone help me explain how they works? Thanks in advance.

I can never remember how I do this because it comes up so infrequently for me. But in C or C++, what is the best way to read a character from standard input without waiting for a newline (press enter).  Also ideally it wouldn't echo the input character to the screen. I just want to capture keystrokes with out effecting the console screen.


I'm studying linear regression and there is a concept I can't wrap my head around.  I've heard many times the expression "the independent variable explains $a$% of the variance of the dependent variable $y$. (where $a$ is a number)  The variance of the random variable $y$ is the distance of the observartions from the mean value of $y$. By adding our independent variable $x$ in the model, we want it to explain some of this variance.  I think that when we say the word explain, we don't actually mean that we explain something and it's a metaphorical way of using it but I'm not really sure what it means.  I've found another similar question here but the answer didn't help me understand it.  I'd really appreciate some help!  Thanks

What is it mean by the statement  "X and Y explained a greater proportion of variance in Z than X alone "  More generally, what is it meant when the model "explains more variation" in the dependent variable  -- certainly this is not equivalent to "this explains the variable" more?  Thank you for the insight into this basic question.


I recently came across this fact in my differential equations book, and haven't been able to figure out how this was computed.

Trig functions are simple ratios, but what do $\cosh$, $\sinh$ and $\tanh$ compute? How are they related to Euler’s number anyway?


I am trying to get user device information(device type, IP address....) in lwc but I could only find FormFactor (import FormFactor from "@salesforce/client/FormFactor" by which I can only get device size. Can anyone please help me in this?

We want to perform different logic in our LWC component js controller if the user is viewing our app in mobile.  With aura components, we could do:  if ($A.get("$Browser.formFactor") != 'DESKTOP') {     //do something for mobile only here }   How can we do this with LWC?


Suppose I keep drawing cards from a deck of cards(with replacement, meaning after I draw a card, I switch a new deck of cards but keep the card I draw) until I have drawn both a 1 and a 2. Then What is the expected number of times I would have to draw cards until I can stop?  I have no clue about how to compute such expectation numbers.

We draw letters (a-z) independently and uniformly at random from the alphabet with replacement. If we draw a collection of letters, then we say that we can write a word when the collections contains all the letters needed to spell the word. For example, if we draw ‘a’, ‘c’ and ‘t’, then this collection writes the word ‘cat’, but also ‘act’, ‘at’ and ‘a’.   Let $N$ be the random variable that denotes the number of letters we needed to draw before we can write ‘rowel’ for the first time. Find $E[N]$ and $\text{Var}[N]$.  Could someone help me by showing me how to approach this question?


I want to deselect multiple edges on my model. I currently know how to deselect one edge at a time by CtrlClick, but I am looking for a faster way for that. Deselecting one by one takes forever.  I am using the 3dsmax preset, so the CtrlClick is deselecting edges one by one.  For example, you could use the selection tools in 3dsmax (lasso, circle, box, spray etc.) to quickly deselect verts / edges / faces by Alt(Click+Draw a region).

I have a .STL file and all of the faces have been converted to triangles so there are hundreds of long thin triangles.  Is there a effective way to select all of the faces in a small area? Something like a circle and when you click every face under that circle is selected.


What is the best way to get Drupal to automatically perform security updates? And are people commonly employing such a method?   For motivation, consider this: Drupal just released a  about a recent  saying:      ...You should proceed under the assumption that every Drupal 7 website was compromised unless updated or patched before Oct 15th, 11pm UTC, that is 7 hours after the announcement.   Fortunately I caught this one and performed the update manually one hour after the announcement. But what if I hadn't? I'd like to have an automatic update process in place to give me some piece of mind.   And I'd like for this automatic upgrade system to only apply security updates. (It just doesn't seem worth the risk to bother with potentially breaking some functionality after an update, unless the update is critical.)

There's a huge security leak in <7.32. So I want to upgrade all my Drupal sites asap without too much worrying about breaking stuff.  But...  $ drush dl drupal-7.32 It's forbidden to download drupal core into an existing core.   This one works:  $ drush up   But that's not what I want now.  How can I only upgrade core to latest version?  drush up drupal is not sufficient on its own: (Sorry about the Dutch. You'll get the gist.)  $ drush up drupal Controle of updategegevens beschikbaar zijn ...                                                            [ok] Update information last refreshed: di, 10/14/2014 - 20:57  Update status information on all installed and enabled Drupal projects:  Naam                               Geïnstalleer  Proposed     Status                                     de versie     version  Administration menu (admin_menu)   7.x-3.0-rc4   7.x-3.0-rc4  Actueel  Drupal                             7.31          7.31         Actueel  Chaos tools (ctools)               7.x-1.4       7.x-1.4      Actueel  Service links (service_links)      7.x-2.2       7.x-2.2      Actueel  Entity API (entity)                7.x-1.5       7.x-1.5      Actueel  Google Analytics                   7.x-2.0       7.x-2.0      Actueel  (google_analytics)  Localization update (l10n_update)  7.x-1.0       7.x-1.0      Actueel  Module filter (module_filter)      7.x-1.8       7.x-1.8      Actueel  Pathauto (pathauto)                7.x-1.2       7.x-1.2      Actueel  Redirect (redirect)                7.x-1.0-rc1   7.x-1.0-rc1  Actueel  Token (token)                      7.x-1.5       7.x-1.5      Actueel  Views (views)                      7.x-3.8       7.x-3.8      Actueel  Webform (webform)                  7.x-3.20      7.x-3.21     Nieuwe versie beschikbaar    No code updates available.


Why does the centre of buoyancy act on the centre of the submerged part of a solid floating in a fluid.  1.One explanation that I came across previously was based on the fact that the fluid displaced by the solid was in vertical equilibrium before solid was immersed. so there must be a force equal to the weight of the volume displaced acting and that too at a point that coincides with the centre of mass of the fluid..  2.My doubt is that is there a mathematical proof of the same?

Consider      Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.   I do not understand why the center of buoyancy is the center of mass of the volume of the displaced fluid.  In principle it could be another point, for istance the center of mass of the object (not the displaced fluid) or maybe a point of the displaced fluid but not the center of mass.  Is there an simple way to understand why the center of buoyancy located in the center of mass of the displaced volume of fluid?


I don't know why I am getting this error. I tried to use breakpoint and found out it gives me the error when it wants to go through the 4th for loop (for tt=0...). //Constraints 12 for (cc = 0; cc < NumberOfCourses; cc++)     for (ww = 0; ww < AvailableWeeks; ww++) {         IloExpr Constraint12;         for (rr = 0; rr < AvailableRooms; rr++)             for (tt = 0; tt < AvailableTimeSlots; tt++) { //error line                 Constraint12 += Z[cc][rr][tt][ww];             }         mod.add(Constraint12 = AN[cc][ww]);         Constraint12.end();     }

I know that the compiler will sometimes initialize memory with certain patterns such as 0xCD and 0xDD.  What I want to know is when and why this happens.  When  Is this specific to the compiler used?  Do malloc/new and free/delete work in the same way with regard to this?  Is it platform specific?  Will it occur on other operating systems, such as Linux or VxWorks?  Why  My understanding is this only occurs in Win32 debug configuration, and it is used to detect memory overruns and to help the compiler catch exceptions.  Can you give any practical examples as to how this initialization is useful?  I remember reading something (maybe in Code Complete 2) saying that it is good to initialize memory to a known pattern when allocating it, and certain patterns will trigger interrupts in Win32 which will result in exceptions showing in the debugger.  How portable is this?


I'm a German native speaker and sometimes I'm confused about how to use the above-mentioned  words.  For example,      This idea is good, and that idea is good too   Is this OK, or should I use, instead of too,  the word also?  Please give some examples and explanations.

I have sent this e-mail to Aman also. I have sent this e-mail to Aman too.   Which one is correct? What is the exact difference between the two? Please explain.


When I run a perl script  in bash, I want to set the value of a variable TEXMFVAR needed by the  script, and pass it to the script.  I googled around, and thought  I found a solution:  $ TEXMFVAR=/usr/local/texlive/2014/texmf-var sudo /usr/local/texlive/2014/texmf-dist/scripts/pax/pdfannotextractor.pl --install   But it seems TEXMFVAR is still empty in the script, because it creates a directory $TEXMFVAR under my current dir. I am puzzled.   $ ls \$TEXMFVAR/* $TEXMFVAR/ls-R  $TEXMFVAR/scripts: pax   Do I need to export the variable?  Is this a problem of usage of environment variables?  Note: My original problem is about texlive  and here

Is this a correct way for passing an environment variable in sudo ?  sudo -u www-data -b env FOOBAR="foobar" /home/user/folder/daemon


I have a hardware which is Ublox EVK-M8T kit, with the GPS antenna.  I also install the gpsd and ntp in the Ubuntu system.  I check to make sure all are working probably, such as:    turn of daemon os:  sudo service gpsd stop  Remove any sockets gpsd might have left behind:  sudo rm /var/run/gpsd.sock  make sure there is no instance of gpsd running:  sudo killall -9 gpsd ntpd  find the current USB devices connected to the RPI:  ls /dev/ttyACM0  check that your device is emitting data, and save MNEA message to logfile:  gpsmon /dev/ttyACM0 -l logfile  and also work with:   cgps -s xgps  reconfiguration file:  sudo service ntp reload  see status overtime, show us all the clocks and what times are?  sudo ntpq -p  check ntp status:   service ntp status  change the server:   sudo vim /etc/ntp.conf  and:  ntpdate -d 192.168.1.231    ....  Those are steps that I was trying to set up gpsd and ntpd, but I still do not understand, why do I have to do that?  How can I get an get Ubuntu system with ntpd receiving data from GPS through USB and set clock accuracy?  Thank you.

I would like Ubuntu to automatically synchronize my system clock with a timeserver at startup.  However, my PC isn't connected to the Internet until after I've logged in (plus 5 - 10 seconds for good measure).  How can I set it to do this?


Hi my question is how to upgrade to jelly bean? I have a Samsung Galaxy 2. I am use to Jelly bean that what my tablet is,so I am 1st time user of this phone I purchased. I was trying in google store to get my game on my phone and it said it was not compatible.So went in setting saw software update but when I tried to it said no firm ware. It is a second hand phone so I don't know what to do. I thought maybe if I could upgrade to jelly bean it all problems. Idk if I could find a site that has a free upgrade download. If you know a site I can do this please let me know. I don't have a USB cable just a home charger, do I need one? Ty in advance, Wendy

There are several reasons to be looking for a ROM:   Upgrading or downgrading your stock ROM Looking for firmware from a different region/language Flashing a custom ROM for different features, removing bloat, etc.   But where can one find ROMs in the first place?  What sites are likely to have the ROM I need?  ; please add to the wiki answer instead of posting separate answers.  See also:


What is the easiest way to obtain the capital version of tipa's letter \textyogh (which is apparently LATIN CAPITAL LETTER EZH U+01B7, Ʒ)?

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


I want to describe: a job-position that is given to someone as a way to appease the person, but the position holds no real function.  Context:     He was, due to his importance to the secret project, offered an honorary ____ with disproportionally lucrative payment.   The job is given by the authority to the person as a way to basically bribe him with undeserved salary, because he won't be given any real task. The emphasis here is payment, and not power, so "figurehead" would be inappropriate.

What is the word used to describe a job given to a person just to give him/her the status of being in employment? The role does not effectively fulfil a purpose other than status and prestige. I read this word in an article months ago and have not been able to find it. I am referring to an adjective, not nepotism or tokenism, and the concept is more general.  Example sentence:     Jim has a |word| job, it was given to him just to give him status and prestige.


Prove $$\sin x\ge x-\frac{x^3}{3!}$$ for $x\ge 0$.  I know that a calculus/continuity proof exists, but I am curious if this can be proved without that. Here is a sketch I have made.; we will use for $x\ge 0$;  $$\sin x\le x\le \tan x$$  proof of this see   I got a weaker bound : $$\tan\left(\frac{x}{2}\right)\ge \frac{x}{2}$$ $$\sin\left(\frac{x}2\right)\cos\left(\frac{x}2\right)\ge \frac{x}{2}\cos^2\left(\frac{x}{2}\right)$$ $$\sin x= x\left[1-\sin^2\left(\frac{x}{2}\right)\right]\ge x\left(1-\frac{x^2}{4}\right)= x-\frac{x^3}{4}$$ Thus $$\sin x \ge x-\frac{x^3}{4}$$ As you can see is there any way I can take this to strengthen the inequality, to get $$\sin x\ge x-\frac{x^3}{6}.$$ Also could this possibly be extended by strengthening inequality further to get the Taylor series. I think I am going too far!

I'd like to prove the following via Taylor approximation : $$x > 0 \implies \sin x > x-\frac{x^3}{3!}$$ I tried to estimate the error but I found $E_3(x) \leq |\frac{x^4}{4!}| $, which doesn't give information about the sign of the error. Then, I tried to compare the sign of each couple of terms in the error but it gives the right result just when $0<x \leq1 $ because in this case $$(\frac{x^5}{5!} - \frac{x^7}{7!} )+(\frac{x^9}{9!} -\frac{x^{11}}{11!} ) + \dots$$ all the couples are positive. But from here I don't know how to continue to include the case $x>1$. How can I find a way using Taylor approximation ?  (I know other methods like derivatives can be used, but I want just to use Taylor if possible). Besides, Is there a general method to find the intervals where the sign of the error is positive/negative?


I have to prove that      $$\langle x^2-x-1 \rangle \text{ is not a maximal ideal of } \mathbb{Z}[x].$$   My attempt: I am not that much familiar with field theory but i know that an ideal $I$ is maximal over a commutative ring $R$ iff $\displaystyle\frac{R}{I}$ is a field ,but here $\mathbb{Z[x]}$ is a UFD and given ideal is  irreduicble over $\mathbb{Z[x]}$ so it is prime and thus $\displaystyle\frac{\mathbb{Z[x]}}{\langle x^2-x-1 \rangle }$ is an integral domain ,but don't know about is it field or not?

Let $f$ be a nonconstant element of ring $\mathbb Z[x]$. Prove that $\langle f \rangle$ is not maximal in $\mathbb Z[x]$.   Let us assume $\langle f \rangle$ is maximal. Then $\mathbb Z[x] / \langle f \rangle$ would be a field. Let $a \in \mathbb{Z}$. Then $a + \langle f \rangle$ is a nonzero element of this field, hence a unit. Let $g + \langle f \rangle$ be its inverse. Then $a g - 1 \in \langle f \rangle$, hence $ag(x)-1 = f(x)h(x)$ for some $h \in Z[x]$, hence $ag(0) + f(0)h(0) = 1$, thus $(a,f(0))=1$ for all $a \in \Bbb Z$, contradiction, hence the proof.  Is my argument correct? Is there any other method?


Let A be a linear map from $R^n$ to $R^m$, Then  Prove that $null(A)^{\bot} = range(A^T)$.  So far, I can easily show that $range(A^T) \subset null(A)^{\bot}$. See below.  if $x \in range(A^T)$, then $(x,n)=(A^Tu,n)=(u^T,An)=(u^T,0)=0$ for all $n \in null(A)^{\bot}$.  But I cannot proof the opposite direction.  How can I prove that if $x \in null(A)^{\bot},$ then $ x \in range(A^T)$?

How can I prove that, if $V$ is a finite-dimensional vector space with inner product and $T$ a linear operator in $V$, then the range of $T^*$ is the orthogonal complement of the null space of $T$?  I know what I must do (for a $v$ in the range of $T^*$, I have to show that $v\perp w$ for every $w$ in $\ker(T)$ and then do the opposite), but I don't know how to show that this inner product is zero.


I've built a custom theme for a Woocommerce shop and changed the custom product price front its default location to another.  This works well with single products, or variable products with the same price between variations.   However, when viewing a variable price product, I get two price tags displayed, istead of just updating the existing one.  Example   I've tried a jquery approach to update the upper field and hide the other, but it just doens't feel to be the right approach.  Can anyone point me in the right direction?

Which file (or files, if more than one) do I need to edit to re-arrange the Product Page?  I want to make some basic layout changes to the default Woocommerce product page. Specifically, I want to put the Order stuff just below the Price, and push the description down.  In other words, swap the Short Description with the Order Stuff (Attributes, Add to Cart, SKU, etc.)  Here is a screenshot of what I want to do:


When I run sudo apt update It is returning $ sudo apt update Hit:1 http://th.archive.ubuntu.com/ubuntu focal InRelease                                                                                Hit:2 http://th.archive.ubuntu.com/ubuntu focal-updates InRelease                                                                           Hit:3 http://th.archive.ubuntu.com/ubuntu focal-backports InRelease                                                                         Get:4 http://security.ubuntu.com/ubuntu focal-security InRelease [109 kB]                                                                   Hit:5 https://download.docker.com/linux/ubuntu focal InRelease                                                                              Hit:6 https://deb.nodesource.com/node_15.x focal InRelease                                                                      Hit:7 https://linux.teamviewer.com/deb stable InRelease                         Fetched 109 kB in 2s (52.1 kB/s)                          sh: 1: /usr/lib/cnf-update-db: not found Reading package lists... Done E: Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/lib/command-not-found/ -a -e /usr/lib/cnf-update-db; then /usr/lib/cnf-update-db > /dev/null; fi' E: Sub-process returned an error code

The terminal gave me these errors when updating the software with sudo apt update.    Hit:1 http://it.archive.ubuntu.com/ubuntu bionic InRelease Hit:2 http://it.archive.ubuntu.com/ubuntu bionic-updates InRelease                                                                                Hit:3 http://it.archive.ubuntu.com/ubuntu bionic-backports InRelease                                                                                Hit:4 http://security.ubuntu.com/ubuntu bionic-security InRelease                                      Hit:5 http://archive.canonical.com/ubuntu bionic InRelease                 Traceback (most recent call last):                       File "/usr/lib/cnf-update-db", line 8, in <module>     from CommandNotFound.db.creator import DbCreator ModuleNotFoundError: No module named 'CommandNotFound' Reading packages list... Done E: Problem executing scripts APT::Update::Post-Invoke-Success     'if /usr/bin/test -w /var/lib/command-not-found/ -a -e /usr/lib/cnf-update-db;       then /usr/lib/cnf-update-db > /dev/null; fi'   E: Sub-process returned an error code     These are the results of sudo apt install --reinstall command-not-found  Reading package lists... Done  Building dependency tree         Reading state information... Done 0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded. Need to get 0 B/5.188 B of archives After this operation, 0 B of additional disk space will be used. (Reading the database ... 225797 files and directories currently installed.) Preparations for extracting ... / command-not-found_18.04.4_all.deb ... Extracting command-not-found (18.04.4) on (18.04.4) ... Configuring command-not-found (18.04.4) ... libdvd-pkg: Package libdvdcss2-1.4.2-1 was removed, stop processing...   When I tried the command sudo apt update again after reinstalling command-not-found, the results were the same as described in the first text block.


I need a help, please.  I'm using \citep command to cite a reference, and the result is "(Zhang e Zu, 1999; Zhang et al., 2001)".  But my I need the result as "(ZHANG e ZU, 1999; ZHANG et al., 2001)."  What I can to do this?  Thanks

For my PhD thesis I have to typeset the author's family name in capital letters in the citation call-out but not in the bibliography itself. So, I mean:  cite: SCHULTZ, 1971 bibliography: Schultz, T. W. (1971): Book name.  In addition, for several authors I should use hyphen, like this:  JOSHI - PETERSON, 2013  Could anybody help me how one does this? Thanks. What I tried so far: (but I needed capital letters in cite) \documentclass[12pt,a4paper]{report}   \usepackage[latin1]{inputenc}   \usepackage{amsmath}   \usepackage{amsfonts}     \usepackage{amssymb}    \usepackage[authoryear]{natbib}     \bibliographystyle{apalike}    \begin{document}    blablabalbal~\citealp{aas2004modelling}    \bibliography{bibfile}      \end{document}


when I try to use sudo -I command, I get this error:  sudo: /etc/sudoers is owned by uid 33, should be 0 sudo: no valid sudoers sources found, quitting sudo: unable to initialize policy plugin   so I tried to use pkexec chown -R root:root /etc/sudoers and I get this error:  polkit-agent-helper-1: error response to PolicyKit daemon: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: No session for cookie ==== AUTHENTICATION FAILED === Error executing command as another user: Not authorized  This incident has been reported.   Does anyone know what to do with this?  EDIT:  I think it is because I ran sudo chown www-data:www-data / by a mistake, but I stopped it after few seconds.  What do you think, I should do with that?

I accidently ran  sudo chmod 755 -R /   instead of  sudo chmod 755 -R ./   I stopped it after few seconds, but now there is some problems such as  sudo: must be setuid root   How can I revert permissions back?


For $c \in \mathbb{R}$, the equation $\dfrac{1}{x-a_1} + \dfrac{1}{x-a_2} + \ldots + \dfrac{1}{x-a_n} = c$ has $n-1$ real solutions   The follow up to this is that prove that the equation has $n$ solutions if $c \neq 0$.  Here $a_1 < a_2 < \ldots < a_n$ and $c \in \mathbb{R}$. How does this equation even have solutions, I'm really confused with this!

Suppose that $a_{1}<a_{2}<…<a_{n}$. Prove that the equation  $ \frac{1}{x-a_{1}}+\frac{1}{x-a_{2}} +…+\frac{1}{x-a_{n}}=c$ has exactly $n-1$ roots if $c=0$ and $n$ roots if $c\neq 0$.    I am absolutely not sure but I think I need to use Rolle's theorem on this. Multiply both sides by $x-a_{1}$ so we get:  $1+\frac{x-a_{1}}{x-a_{2}}+…+\frac{x-a_{1}}{x-a_{n}}-c(x-a_{1})=0$. Now it is defined for $a_{1}$ but not for $a_{2},…,a_{n}.$. If we consider the interval $(a_{1}-\varepsilon,a_{n}+\varepsilon), \varepsilon>0$ we get..nowhere. I want to create an interval with endpoints that are solutions to the equation. Yet I don't know how to prove that there are exactly $n$ roots(Fundamental theorem of algebra can't be used).


There are certainly no clear boundaries within science and philosophy. Science is about knowledge of nature, hypothesis, tests and repetition, and philosophy is about knowledge generated purely by reason, not objectively verifiable by the scientific method (hope providing a good approximation, if not, thanks in advance for any correction).  How do we know whether a discipline is science or philosophy?   For example, the systems theory seem to match both descriptions.    A rock can be perfectly described by the systems theory from a scientific approach (e.g. we can test with the scientific method that rocks are systems because they are formed by parts holding persistent relations, for example, we can test that molecules joined by molecular bonds under X conditions form rocks); we can test it several times and prove that the systems theory provides a valid and testable hypothesis regarding a natural entity. Or, a rock can also be described from a philosophical approach by the same theory: we can state that as any other system, rocks tend to keep existence as a whole because their parts keep relations (there is no way to prove otherwise: only rocks formed by relations can exist, and the lack of relations between whatever parts can't be considered a rock).   This question is about a discipline, not about philosophy/science. There are clear differences between them, and the point is to assess whether a discipline can be considered to be mostly one or the other.

While philosophy and science as held as separate disciplines (and often taught in completely different colleges within a university [i.e. College of Liberal Arts vs. College of Science]), it is patently clear that there is an immutable relationship between philosophy and science. Philosophy can often be seen as providing justification for particular scientific theories -- but why/how is this so?  In science:   A theory must have observable consequences that can be tested and be falsified.   Theories also must agree with previous theories in the domains where they had been successfully tested.   For example,  special relativity reduces to Newton mechanics in the domain of velocities much less than the speed of light.  In philosophy, while new theories must comply with existing theories, there is clearly much less testing/retesting.  So, how does philosophy fit into this framework while maintaining the rigor required for scientific inquiry?  Are there any examples of philosophical discussions that have significantly influenced or changed scientific theory?


i tried the below code but I am not getting the reason why it is happening?  x=2 y=2 print(id(x),id(y))   in above I have got like below 140732101468592 140732101468592  but if I tried with the float type data like below  x=2.0 y=2.0 print(id(x),id(y))   I have got the output like below 2226214428496 2226204728400  why am I getting same id for integer variable with same value but not for float variable with same values?

Why does the following behave unexpectedly in Python?  >>> a = 256 >>> b = 256 >>> a is b True           # This is an expected result >>> a = 257 >>> b = 257 >>> a is b False          # What happened here? Why is this False? >>> 257 is 257 True           # Yet the literal numbers compare properly   I am using Python 2.5.2. Trying some different versions of Python, it appears that Python 2.3.3 shows the above behaviour between 99 and 100.  Based on the above, I can hypothesize that Python is internally implemented such that "small" integers are stored in a different way than larger integers and the is operator can tell the difference. Why the leaky abstraction? What is a better way of comparing two arbitrary objects to see whether they are the same when I don't know in advance whether they are numbers or not?


I saw a function like   public FuncA(string param1, IList<SqlParameter> sqlParamsList)   I wonder why the author was using IList instead of List? Which one is better? I know the difference between them is one is interface, the other one is class. So my final question is when to use which?

I know that IList is the interface and List is the concrete type but I still don't know when to use each one. What I'm doing now is if I don't need the Sort or FindAll methods I use the interface. Am I right? Is there a better way to decide when to use the interface or the concrete type?


This is my code:  from random import randint  ant1 = 1 ant2 = 2 ant3 = 3 ant4 = 4 cntNum = 0 no = 0 yes = 0  def antMove(antNum):     randomNum = randint(0,3)     if randomNum == antNum:         yes += 1     else:         print("No")     while cntNum < 20:     antMove(ant1)     antMove(ant2)     antMove(ant3)     antMove(ant4)     cntNum = cntNum + 1  if cntNum == 20:     print(yes)

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


Fatal error:  Uncaught exception 'Exception' with message 'String could not be parsed as XML' in Stack trace: C:\xampp\htdocs\trendfeeds.php(48): SimpleXMLElement->__construct('') {main} thrown on line 48       echo '<?xml version="1.0" encoding="utf-8"?>'; echo '<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/">'; echo '<channel>'; echo '<title>Games - Free Download - Freshwap</title>'; echo '<link>http://www.freshwap.com/</link>'; echo '<language>en</language>'; echo '<description>Games - Free Download - Freshwap</description>';  $url="http://www.google.com/trends/hottrends/atom/hourly"; $beg="<li>"; $end="</li>"; $tryscrape="1"; $end=str_replace('/','\/', $end); $beg=str_replace('/','\/', $beg); $end=str_replace('\"','"', $end); $beg=str_replace('\"','"', $beg);  if($tryscrape==1) { $data = file_get_contents($url); $regex = '/'.$beg.'(.+?)'.$end.'/'; $count=1; preg_match_all($regex,$data,$match,PREG_SET_ORDER); foreach ($match as $result) { $link = $result[1]; $link=strip_tags($link); echo '<item>'; echo '<title>'.$link.'</title>'; echo '<description><![CDATA[';  ?>  <?php  function google_blog_feed($path){ $ch = curl_init(); curl_setopt($ch, CURLOPT_URL,$path); curl_setopt($ch, CURLOPT_FAILONERROR,1); curl_setopt($ch, CURLOPT_RETURNTRANSFER,1); curl_setopt($ch, CURLOPT_TIMEOUT, 15); $retValue = curl_exec($ch);                       curl_close($ch); return $retValue; } $sXML = google_blog_feed('http://blogsearch.google.com/blogsearch_feeds?hl=en&q='.$link.'&ie=utf-8&num=10&output=rss'); $oXML = new SimpleXMLElement($sXML); // Error on this line foreach($oXML->channel->item as $oDocuments){ $title = strip_tags($oDocuments->title); $url = $oDocuments->link; $description = $oDocuments->description; echo $description; }  ?>  <?php  echo ']]></description>'; echo '<category><![CDATA[Google]]></category>'; echo '</item>'; } }  echo '</channel>'; echo '</rss>';  ?>   Please help me on this...

I have to generate a xml file dynamically at runtime. Please help me in generating the below XML file dynamically using PHP.  <?xml version="1.0" encoding="UTF-8"?> <xml>  <track>      <path>song1.mp3</path>      <title>Track 1 - Track Title</title>  </track>  <track>      <path>song2.mp3</path>      <title>Track 2 - Track Title</title>  </track>  <track>      <path>song3.mp3</path>      <title>Track 3 - Track Title</title>  </track>  <track>      <path>song4.mp3</path>      <title>Track 4 - Track Title</title>  </track>  <track>      <path>song5.mp3</path>      <title>Track 5 - Track Title</title>  </track>  <track>      <path>song6.mp3</path>      <title>Track 6 - Track Title</title>  </track>  <track>      <path>song7.mp3</path>      <title>Track 7 - Track Title</title>  </track>  <track>      <path>song8.mp3</path>      <title>Track 8 - Track Title</title>  </track>


Hi all I am a software engineer working on cloud computing(Mostly scripting). I wanted to learn web development and started with some basic course and learnt HTML,CSS. But when i came to JavaScript in the beginning it was fine, but later when it came to dynamic elements i started getting difficulty in eventListner to those dynamically created element with plan JavaScript. whereas with jquery its way easy with function like on(). The thing is, while learning all these i came up with lots of articles and youtube videos about javascript have evolved a lot and jQuery not so much relevant in 2020. so my question is   1) As a beginner in web development Should i avoid jquery totally.   2) or jquery is still very much thriving and should i mix both and learn.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I'm trying to rewrite using htaccess all traffic over SSL (https). However my certificate gives an error on mobile, so I Want mobile traffic to go over the normal http protocol.  This is my htaccess:  <IfModule mod_rewrite.c>     #Options +FollowSymlinks   # Options +SymLinksIfOwnerMatch     RewriteEngine On   # RewriteBase / </IfModule> <IfModule mod_rewrite.c>     RewriteCond %{HTTPS} !=on     RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]     RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L] </IfModule>  <IfModule mod_rewrite.c>     RewriteCond %{SERVER_PORT} !^443     RewriteRule ^ https://ugaris.com%{REQUEST_URI} [R=301,L]     RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]     RewriteRule ^(.*)$ https://%1/$1 [R=301,L]  </IfModule>   Just to be clear:  mobile -> http rest -> https all -> non-www

This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not.


I installed Ubuntu 16.04 LTS 64 Bit . I am unable to install Skype . It gives me the following error .  E: Failed to fetch http://bd.archive.ubuntu.com/ubuntu/pool/main/g/gcc-5/cpp-5_5.4.0-6ubuntu1~16.04.1_amd64.deb  Hash Sum mismatch E: Failed to fetch http://bd.archive.ubuntu.com/ubuntu/pool/main/g/gst-plugins-base1.0/libgstreamer-plugins-base1.0-0_1.8.2-1ubuntu0.1_amd64.deb  Hash Sum mismatch   I have seen  and already tried various commands and operations:   I tried sudo apt clean , update , upgrade command .  I tried switching the Servers .

I have Skype installed which I got from the Canonical Partners repository, however after reading  I have come to understand that I can get this latest Alpha version from a repository too though no such update has come to me via the partner repository I have activated. So I have several questions on this matter:   So from which repository (unless that was just a mistake in the article) do I get it from? Is it available under a different name in the partner repository, or is there another official Skype repository? If it is the case that there is a more official repository to get this from then when it is no longer Alpha but instead Stable, will I be able to upgrade to it via the partner repository I currently have enabled or is it no longer support in there?   I am running Ubuntu GNOME 16.04 with GNOME 3.20.


I want to reset my laptop's hard-drive and create a dual-boot system, using both Windows 10 (for gaming) and Ubuntu 18.04 (for everything else). Currently my PC uses Ubuntu 18.04 as sole operating system.   After formatting the hard-disk, what should I install first? Ubuntu or Windows?  I know that in the second case I need to restore the Ubuntu's GRUB because Windows has this tendency of overwrite the master boot record, but that a minor issue for me.   Thanks!

I'd like to install both Ubuntu 12.04 and Windows XP on a Dell laptop, and I was thinking about using a dual boot structure, and using the bulk of my hard drive as empty hard drive space to share files between the two operating systems (so choice of file system type is very important in this set-up).     The kind of partitioning structure I would like to use is  Partition 1 - Ubuntu 12.04 (root) (20GB)  Partition 2 - Ubuntu /home        (20GB)  Partition 3 : Free Space          (560GB)  Partition 4 : Windows XP          (35GB)  Partition 5 : SWAP                (3GB)  (Total Hardrive Capacity is ~640GB)    My question is; what is the best way to go about setting up this kind this system?   Should I install Windows XP first and setup the partitions, and then install Ubuntu which I believe will install the GRUB bootloader for OS booting choice   or   Do I install Ubuntu first, setting up the available partitions and then perform a WIndows install?  Please let me know if there is anything in this setup that I have left out and should know about, including things related to setting particular partitions as logical or primary, and whether the boot partition and the filesystem partition should actually be two separate partitions.


This may seem trivial, so my apologies, I've searched for a quantitative answer and couldn't find anything explicitly.  If a moving object has some velocity, and experiences a decrease in mass will the object lose velocity? My thoughts: Example, a cart is rolling and I take a box off the cart while it's in motion does the cart lose velocity due to the decrease in mass, or maybe it can be shown that the momentum decreases which equates to a decrease in velocity.

I faced a problem:     A truck filled with sand has a mass of $6*10^3$ kg. It's moving at a constant speed of 20 $kms^-1$. If at one moment, sand starts to fall through a hole normal to the motion of the truck from the truck with rate 5 kg/s(due to a downward gravitational force); what would be the force needed to keep the truck at same constant initial speed?   Neglect air drag, friction etc.   I am only concerned with if the momentum of the truck in the direction of it's motionn would conserve.  My attempt: No, it won't. Because conservation of momentum only works for closed systems. The sand pouring out and the object creating the gravitational field are in a closed system (not in terms of invaraint mass, but in terms of no external force). But, all other sand particle and the truck is out of this closed system. So, according to inertia of motion, all other particles will keep up the same velocity. So, necessary force $0N$  Feel free to point out my mistakes.


I have dual boot Windows 7 and Ubuntu 13.10.  I want to upgrade the version of Ubuntu to 15.04. Will that affect my data? And is that possible? If yes, how can I do that?

Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc


I want to build a Linux system from scratch, and i want the most basic Ubuntu package. If possible only the command line and that's it. What should i download for it?

I keep having to re-install Ubuntu after trying advice.  This is very frustrating.  All I want is to boot to a Linux command prompt.  Please help!


I'm trying to make an array[6] of random numbers (NO REPEATED)  void rnd::process(void){     rndArr[0] = (1+rand()%(45-1));     assign1:     rndArr[1] = (1+rand()%(45-1));     if(rndArr[1]==rndArr[0])goto assign1;     assign2:     rndArr[2] = (1+rand()%(45-1));     if((rndArr[2]==rndArr[1])||(rndArr[2]==rndArr[0]))goto assign2;     assign3:     rndArr[3] = (1+rand()%(45-1));     if((rndArr[3]==rndArr[2])||(rndArr[3]==rndArr[1])||(rndArr[3]==rndArr[0]))goto assign3;     assign4:     rndArr[4] = (1+rand()%(45-1));     if((rndArr[4]==rndArr[3])||(rndArr[4]==rndArr[2])||(rndArr[4]==rndArr[1])||(rndArr[4]==rndArr[0]))goto assign4;     assign5:     rndArr[5] = (1+rand()%(45-1));     if((rndArr[5]==rndArr[4])||(rndArr[5]==rndArr[3])||(rndArr[5]==rndArr[2])||(rndArr[5]==rndArr[1])||(rndArr[5]==rndArr[0]))goto assign5;     }   Can you write a more orthodox code than this?, I'm learning

I'd like to generate unique random numbers between 0 and 1000 that never repeat (i.e. 6 doesn't show up twice), but that doesn't resort to something like an O(N) search of previous values to do it. Is this possible?


Hi hope somebody can help me, trying to plot  a graph of \frac{1}{\pi\sqrt{x(20-x)}} and really struggling, thanks in advance

i know how to draw axis and everything else except the function here , please give me hint to plot this function    Thanks for the help


In Representation of electromagnetic waves we show both electric and magnetic fields perpendicular to each other and having zero magnitude at one point and maximum at other point. This representation and understanding of EM waves violating law of conservation of energy...

I'm starting to study electromagnetic waves and as i understand, an electromagnetic wave projects a varying electric field. This electric field can in turn give forces of repulsion/attractions to the electrons and protons it passes very close to. Why doesn't it violate the law of conservation of energy?


I hear a lot of people use “I feel like” + subject + verb, but I'm not sure whether it's grammatically correct. Someone once told me it was incorrect.  For example, if someone said, “I feel like I annoy people,” would it be considered grammatically correct or incorrect?  If it's incorrect, should “I feel as though” or “I feel that” be used?

I want to go for wine and tapas, it's correct to say this? - I feel like wine and tapas. - I feel like I want wine and tapas. - What about going for wine and tapas?


Can anyone of you help me overwrite something from my Spherocylinder array?  I've got this currently:     public Spherocylinder deleteSpherocylinder(String labelIn)    {       Spherocylinder result = null;       int index = 0;              for (int i = 0; i < elements; i++)       {          if (object[i].getLabel().equalsIgnoreCase(labelIn))          {             //My issue is with the line of code below, i know this is              //how i delete an element in an arraylist but i know want to              //delete it using an array.             result = object.remove(i);          }       }        return result;    }   where (object) is the name of my Spherocylinder array and (elements) is an int I use which tells me how many elements i have in my array. This line of code is just one of my methods in my class, any help would be appreciated.

Given an array of n Objects, let's say it is an array of strings, and it has the following values:  foo[0] = "a"; foo[1] = "cc"; foo[2] = "a"; foo[3] = "dd";   What do I have to do to delete/remove all the strings/objects equal to "a" in the array?


A member just joined our clan, but is ineligible for war.  She was not previously in a war, and her profile doesn't have the ineligible symbol and time like it would for others, but it still says she can't opt in for war.   Is this a bug or is there an explanation?

I am currently in a clan with three members. When we tried to initiate a clan war it said we had insufficient clan requirements. Does anyone know what the full requirements are? Is there a minimum clan member requirement?


I've a JSON property which needs to be updated with base64.  The flow is:  prop_val=`base64 --wrap=0 < $prop_txt` sed -i 's@"property_specific": ""@"property_specific": "'"${prop_val}"'"@g' $final_json   It errors out with: line 22: /bin/sed: Argument list too long  The base64 string (single line) is very long. How else can I update the property w/o sed?  Note: the double quotes in format.  Update:   Created place holder unique string, to remove double quotes complexity. Tried sed -f; didn't work.   Tried:       sed -i -f - $final_json << EOF; 's@placeHolder123456@'"${prop_val}"'@g'; EOF   Error:  line 27: warning: here-document at line 23 delimited by end-of-file (wanted `EOF') line 28: syntax error: unexpected end of file   Tried placing it in a function to avoid EOF error, but it didnt work. Function:  update_prop_specific() {     sed -i -f - $1 << EOF     s@placeHolder123456@$2@g     EOF }   Suggestions?

I'm trying to execute this command  sed -i -e "s/BASE_64/$BASE_64/" FILE_NAME   where $BASE_64 is a base 64 representation of a file content.  sed gives me an error since the string is too long.     Argument list too long   How is it possible to avoid this error?


Recently I was exposed to a lot of uses of "She don't + infinitive" ( + don't), instead of "she doesn't + infinitive" ( + doesn't). I'm not sure if it is a mistake or just accepted usage sometimes.   I found it in a very famous songs such as:   "" by Bon Jovi   Also in  (in 3:04)     But she don't know you like I know you Slim, no one does   She don't know what it was like for people like us growin' up, you gotta call me man   I'll be the biggest fan you'll ever lose   Sincerely yours, Stan, P.S. we should be together too   You can find a lot more by searching in you tube "he don't" or "she don't".

Here's from an old song (1963) "" by Lesley Gore.       She don't know that she's a lucky girl   Here's another example, "Silence is Golden" (1964) by The Tremeloes [YouTube ]      Oh, don't it hurt deep inside to see someone do something to her.   I wonder how common it is to say "She don't" or "don't it". Do native English speakers often use these?  By the way, Lesley Gore is American, and the Tremeloes is British.


If there were two charges placed at a large distance, won't their (say) magnetic fields interact? What if that large distance is something like close to infinity? Even if they experience a feeble force from each other, doesn't that imply that the magnetic field lines are not closed, as the particle could have been placed anywhere around the source charge at any distance?  Would not this generally say that every electrically charged particle in the universe is part of an infinitely large magnetic field?

What do we mean with  and ? I can not find a way to relate magnetic monopoles and dipoles with electric ones. I do not understand their outcomes. Also,what is their role in Gauss' law for magnetism (the net magnetic flux through a closed surface is zero)?  I read that the magnetic dipoles are essential for the meaning of this law. Why? If magnetic monopoles existed,then why would the law not be valid? Lastly,why do we say that the magnetic field is divergeless? Some physicists try to find a magnetic monopole (something Dirac tried to explain i think). So if they actually find one, what does that mean? For a classic magnet(N-S) we know that we have charges inside moving in a circular motion and they althogether form that magnetic field of the magnet. So how does finding a magnetic monopole change this? What does it mean for those small currents?    (I might understood something wrong here so enlighten me please!)


Suppose I read a question that has a net vote level of -3.  Maybe it's even been flagged.  Would it be overkill to downvote it?  Does the answer depend on whether it's a brand-new user?  Is there a negative number at which you would hesitate to downvote?  In minigolf, there's usually a suggested maximum number of strokes per hole, to prevent people from getting too discouraged.

Is down-voting an already heavily down-voted/closed question kind of like kicking a dead horse? Is this bad practice?


Steam, among other annoying things, seems to add games to my library spontaneously. For example, it recently added the game "Contagion - 2 hours left" to my library which I have no interest in installing and I cannot figure out how to get rid of it.  Also, they tricked me by suggesting that there was some kind of "free" deal over the Labor Day weekend for getting a free copy of Call of Duty: Ghosts, but of course, after I spend 4 hours downloading it and try to click the "Ready to Play" button, it announces "Failed to Start (no licenses)".  How can I get this junk out of my library?

I like how Steam presents my library to me.  However, there is one thing that keeps irritating me every time I open Steam: the Team Fortress 2 Beta.  I don't want it, yet it is always in my games list.  I've tried contacting Steam Support since it seems I was unable to remove the games myself so far. This was their response; their only solution was to hide the games within my library:     Thank you for contacting Steam Support.      Games cannot be removed from a Steam account.      You are free to uninstall the game (right-click on the game name and   select "Delete local content") and change your game list to show only   installed games.      This can be done by clicking "Show" in the upper left-hand corner.   From here, select the "Installed" option.      Another option would be to create a new category for only this title   and then minimize the category.  To create a new Category, please   right click the game and choose "Set Category".      Then click on the category name in your Library to collapse the   category.      If you have any further questions, please let us know.   Thus, is there a way to remove games from my Steam library permanently? To clarify, I don't mean just by uninstalling, I mean by removing it from my library forever.


I am using TeXnicCenter for writing LaTeX documents. Unfortunately, when I am writing in Finnish as I usually do, there is no spell checker in Finnish in TeXnicCenter. All the lines are underlined in red, and this is not nice. I know that there is Voikko for Finnish spell checking in LibreOffice, but is it possible to apply Voikko for TeXnicCenter? TeXnicCenter is using Hunspell; I downloaded the voikko-laaja.oxt file but I could not find in this package any files with .aff and .dic suffices.

In the options menu in TexnicCenter you can go to the tab Spelling. There is the option to download a dictionary. I did that, but I still cannot choose this dictionary as default language. How can I change the language?


I have an Iframe with a content loaded from different domain:

   The content of an Iframe can be of different height.  I have a method resize() executing when iframe loads as follows:  function resize() {     var iFrameID = document.getElementById("frame");     if (iFrameID) {         iFrameID.height = "";         iFrameID.height = iFrameID.contentWindow.document.body.scrollHeight + "px";     } }   When running the page I have an access denied error, I'm assuming because of cross-domain issues.  How can I fix that, so my frame's heights will be changed dynamically based on its content?  Thank's

I am working on an iGoogle-like application. Content from other applications (on other domains) is shown using iframes.   How do I resize the iframes to fit the height of the iframes' content?  I've tried to decipher the javascript Google uses but it's obfuscated, and searching the web has been fruitless so far.  Update: Please note that content is loaded from other domains, so the  applies.


How do i run this program ; because in texmaker it gives error.       \documentclass{article} \usepackage{fontspec} \newfontfamily\urdufont[Script=Arabic,Scale=1.4]{Jameel Noori Nastaleeq} \begin{document} \setRTL \urdufont j j  k i l a d  \end{document}   I get the error message:     ! fatal font spec error The font spec package either requires xetex    or LuaTeX to function   while running the given MWE with ???.

I use TeX Live 2010 and my editor is Texmaker Bidi. It was working probably good but from 2 months ago I've encountered with the error:   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! ! Fatal fontspec error: "cannot-use-pdftex" !  ! The fontspec package requires either XeTeX or LuaTeX to function. !  ! You must change your typesetting engine to, e.g., "xelatex" or "lualatex" ! instead of plain "latex" or "pdflatex". !  ! See the fontspec documentation for further information. !  ! For immediate help type H <return>. !...............................................   when I'm trying to load xepersian LaTeX.  but I do not know how can I change pdfLaTeX to XeLaTeX.    This is the second edit of my question .   the code is :    \documentclass{article} \usepackage{pstricks} \usepackage{pst-bezier} \usepackage{xepersian}  \settextfont{XB Zar}  \setlatintextfont{Junicode}  \setdigitfont{XB Zar}  \begin{document}  !سلام دنیا \begin{pspicture}(3,3) \psbcurve(1,2)(5,7)(2,2)(12,3) \end{pspicture}  \end{document}   but the output does not include the shapes .


Supose I would like to build a neural network with a sigmoidal function in the output layer, why is there a preference in the use of cross-entropy as a loss function in regard square loss for example? I can understand that in a simple logistic regression the cross-entropy would make the loss a convex function but in neural networks the domain is always non convex, so why the preference?

I am trying to use squared loss to do binary classification on a toy data set. I am using mtcars data set, use mile per gallon and weight to predict transmission type. The plot below shows the two types of transmission type data in different colors, and decision boundary generated by different loss function. The squared loss is $\sum_i (y_i-p_i)^2$ where $y_i$ is the ground truth label (0 or 1) and $p_i$ is the predicted probability $p_i=\text{Logit}^{-1}(\beta^Tx_i)$. In other words, I am replace logistic loss with squared loss in classification setting, other parts are the same. For a toy example with mtcars data, in many cases, I got a model "similar" to logistic regression (see following figure, with random seed 0).  But in somethings (if we do set.seed(1)), squared loss seems not working well.  What is happening here? The optimization does not converge? Logistic loss is easier to optimize comparing to squared loss? Any help would be appreciated.  Code d=mtcars[,c("am","mpg","wt")] plot(d$mpg,d$wt,col=factor(d$am)) lg_fit=glm(am~.,d, family = binomial()) abline(-lg_fit$coefficients[1]/lg_fit$coefficients[3],        -lg_fit$coefficients[2]/lg_fit$coefficients[3]) grid()  # sq loss lossSqOnBinary<-function(x,y,w){   p=plogis(x %*% w)   return(sum((y-p)^2)) }  # this random seed is important for reproducing the problem set.seed(0)  x0=runif(3) x=as.matrix(cbind(1,d[,2:3])) y=d$am opt=optim(x0, lossSqOnBinary, method="BFGS", x=x,y=y)  abline(-opt$par[1]/opt$par[3],        -opt$par[2]/opt$par[3], lty=2) legend(25,5,c("logisitc loss","squared loss"), lty=c(1,2))


I have a container div which has other divs and contents within it and I am trying to center the outer div. For example:   body {   height: 100vh;   width: 100vw; }  .test {   width: 20vw;   height: 20vh;   background-color: green; }  .outer-test {   display: block;   margin: auto; }

Hello

    In the example above, how would I be able to center the div with class of "outer-test"? I have tried to make the display: block and use margin: auto but that doesn't seem to be working.

How can I horizontally center a
 within another
 using CSS?

Foo foo


I just stumbled across a problem I never actually thought about before: decimals in binary. Can someone explain how to do it? Thanks!  Note: If possible, I'd like the answer in decimals not fractions, but this may not be possible.

How would you write a fraction in binary numbers; for example, $1/4$, which is $.25$? I know how to write binary of whole numbers such as 6, being $110$, but how would one write fractions?


I need to export 60 PDFs files so I am thinking if there is a way around to export 60 without having to open each MXD file at a time ?  I am using ArcGIS 10.1 SP1  Build 3143 .

Nico Burgerhart made a fantastic script called "Batch export MXD to PDF" back in 2008.          Any ideas how to implement it in ArcGIS 10? Something using Python perhaps?      Data Driven Pages does not have anything comparable that i could find.  Here's the steps in read me text file which doesn't jive with ArcGIS 10's new menu bar:  Tool: Batch export MXD to PDF Purpose: Saves all MXDs in the selected directory to PDFs in the selected output folder Author: Nico Burgerhart (nicoburgerhart@hotmail.com) Date: 31 Jan. 2007 INSTALLATION NOTES ------------------ 1. Open ArcMap 2. Select Tools > Macro's > Visual Basic Editor 3. Select File > Import file 4. Import BatchExportMXDToPDF.bas 5. Select File > Close and Return to ArcMap 6. Select Tools > Macro's > Macro's 7. Select the BatchExportMXDToPDF mactro 8. Click Run


I forgot my Stack Overflow account and I have logged out of my Gmail account - so I have no other option to get back to my Stack Overflow account. So I created this post to ask this question.  Is there any way I can know the e-mail address of this account? I have forgotten my e-mail address since I have created so many e-mail address already. Here is my account     If I know the e-mail address I can login again to my Gmail and it automatically logs me in to Stack Overflow.

I accidentally posted a question without being logged in. Is there a way to associate that question with my account?   For more information, visit "" in the .   a.k.a. How can you link a registered account to a cookie-based account? a.k.a. How do I merge an unregistered account with a registered account a.k.a. Merging users a.k.a. How do I associate anonymous questions I’ve asked with my registered account? a.k.a. Is there a way to claim an unregistered user? (in case anyone searches with those terms)


Suppose $Y\subseteq X$ topological spaces. $X$ and $Y$ are connected.   Let $A$ and $B$ be a separation of $X\setminus Y$ (this means that $A$   and $B$ are disjoint open sets such that $A\cup B=X\setminus Y$). Then   I need to show both $Y\cup A$ and $Y\cup B$ are connected.   I thing I need to prove it by contradiction. So let us assume $K$ and $M$ form a separation of $Y\cup A$. From here i need to show that this assumption leads to either of $X$ and $Y$ being disconnected. I can't show that so easily. Please help

Question is :  Suppose $Y\subset X$ and $X,Y$ are connected and $A,B$ form separation for $X-Y$ then, Prove that  $Y\cup A$ and $Y\cup B$ are connected.  What i have tried is :   Suppose $Y\cup A$ has  separation say $C\cup D$ then all i could see is that   Either $Y\subset C$ or $Y\subset D$ as $Y$ is connected and $ C\cup D$ is separation for a subset that contains $Y$.  Without loss of generality we could assume $Y\subset C$  As $Y\cup A=C\cup D$ and $Y\subset C$  i can say $D\subset A$ (I do not know how does this help)  I have $X-Y=A\cup B$ with $A\cap B=\emptyset$  I have not used connectedness of $X$ till now, So i thought of using that and end up with following :   $X-Y=A\cup B\Rightarrow X=Y\cup A\cup B=(Y\cup A)\cup (Y\cup B)$  I do not know what to conclude from this...   I would be thankful if some one can help me by giving some "hints"  Thank you


I want to cross validate various models to understand which one performs best. I have been referring to Rob J Hyndman's post  here     But I am a little lost as to how to use it on daily data.   my daily time series data starts at 2015-01-01 and ends at 2017-03-31.   Specific questions include:   What should k be in my case?  In mae1 <- mae2 <- mae3 <- matrix(NA,n-k-12,12) instead of 12 will I use 365? In for(i in 1:(n-k-12)) will I use 365?    I have a very high level understanding of the code and I believe that is another reason why I cannot translate this to a daily usecase. Any help in clarifying the problem would be greatly appreciated!

I've been using the  in R to build predictive models for classification and regression.  Caret provides a unified interface to tune model hyper-parameters by cross validation or boot strapping.  For example, if you are building a simple 'nearest neighbors' model for classification, how many neighbors should you use?  2? 10? 100? Caret helps you answer this question by re-sampling your data, trying different parameters, and then aggregating the results to decide which yield the best predictive accuracy.  I like this approach because it is provides a robust methodology for choosing model hyper-parameters, and once you've chosen the final hyper-parameters it provides a cross-validated estimate of how 'good' the model is, using accuracy for classification models and RMSE for regression models.  I now have some time-series data that I want to build a regression model for, probably using a random forest. What is a good technique to assess the predictive accuracy of my model, given the nature of the data? If random forests don't really apply to time series data, what's the best way to build an accurate ensemble model for time series analysis?


I am looking forward to make a 360 degree virtual tour photography of my locality. Could you please suggest the basic specifications of the camera that would be required to do so? What software can I use?

I am currently working to design a flash virtual tour, but I know little about how the photographs are taken.  Ideally I'd like to be able to take a set of 6 shots from a single focal point, and be able to align them seamlessly into a cube form. The other solution is to take a special fisheye image, and stretch it dynamically in flash.  I've seen examples of both as virtual tours, and ones formatted as a rotating cube are more responsive and have a higher image quality. The airbus and Cruden Homes are definitely in the cube format, I'm not entirely certain which format the New York VT uses:        I have a set of questions, the first is the most important, the others may become separate questions if I don't get an answer here:   How are those photos taken? Is there a specific mount that can be used? How long does it take to set up? How much post-processing is necessary on the images?


I am trying to solve the integral: $$I=\int_0^{\pi/2}\frac{1}{1+\tan^{n}x}dx$$ I have tried several methods shown below: $$I(n)=\int_0^{\pi/2}\frac{1}{1+\tan^nx}dx$$ $x=\arctan(u)$ $$I(n)=\int_0^\infty\frac{1}{1+u^n}\frac{1}{1+u^2}du$$ but this does not seem to lead anywhere. I also tried: $$I(a)=\int_0^{\pi/2}\frac{1}{1+\tan^ax}dx$$ $$I'(a)=\int_0^{\pi/2}\frac{\ln(\tan x)}{\left(1+\tan^ax\right)^2}dx$$ but this just seems to complicate it more.  I also see that it can be expressed as: $$I(b)=\int_0^{\pi/2}\frac{1}{1+\tan^b(x)}dx=\int_0^{\pi/2}\frac{\cos^b(x)}{\cos^b(x)+\sin^b(x)}dx$$ a final thought is using the identity: $$\int_a^bf(x)dx=\int_a^bf(a+b-x)dx$$ so: $$\int_0^{\pi/2}\frac{\cos^b(x)}{\cos^b(x)+\sin^b(x)}dx=\int_0^{\pi/2}\frac{\sin^b(x)}{\sin^b(x)+\cos^b(x)}$$ and therefore: $$2I(b)=\int_0^{\pi/2}1dx=\pi/2$$ $$I(b)=\pi/4$$ $$I=\pi/4$$ does this work? Thanks

Evaluate the integral $$\int^{\frac{\pi}{2}}_0 \frac{\sin^3x}{\sin^3x+\cos^3x}\, \mathrm dx.$$  How can i evaluate this one? Didn't find any clever substitute and integration by parts doesn't lead anywhere (I think).  Any guidelines please?


I'm about to use a specific example to highlight a general question  I recently posted an  to   That question was originally asked, and a best-answer chosen, in 2009.  A lot of time has passed and while I believe the question is still relevant and should be asked again today, the answers are now obsolete.  Others have tried to ask the same question because the issue needs to be readdressed.    (2009)  (2011)  (2013)  (2013)  (2013)  (2013)  (2014)  (2014)  (2018)  (2018)   All in all, there are 36 questions linked back to that 2009 original (and I haven't tried to count the number of questions linked as duplicates to those 36...).  It appears to me that this is an issue that needs to be readdressed.  Question: What is the proper procedure for identifying any previous Meta question that should no longer be automatically used as a VTC:Duplicate target but, instead, should be legitimately re-considered?

Seems like this question should have already been asked on Meta, but I could not find it.     is similar, but my question more has to do with requesting an update on a question that is not mine, rather than what to do once it is updated.  My question is how to get an update on an old question. I found  and the question itself (and the updated comment) is outdated and now useless. I would like to ask the question again however I know it will be tagged as duplicate.   How should I go about getting a completely new set of answers for a question like this?


I am trying to write a python script that converts normal text into latex code. So I have to replace $, &, and % by \$, \&, and \% respectively. Also, I have to replace contents inside a square bracket by a blank string since the text was copied from Wikipedia. Here is my code :  import re square_bracket = r"\[[^\]]*\]"   def formatting(text):     no_brackets = re.sub(square_bracket, '', text)     and_ = re.sub('&', '\\&', no_brackets)     percentage_ = re.sub('%', '\\%', and_)     dollar_ = re.sub('$', '\\$', percentage_)     return dollar_   print(formatting("aca & akhil[3255d] 56 $ 72 %"))   Output is:  [Command: python3 -u /home/aca/Documents/python/basics/test.py] aca \& akhil 56 $ 72 \$ [Finished in 0.131s]   I am ok with square bracket, & and %. But dollar sign makes the things messy as it converts normal text into mathematical argument in latex. How do I fix this?

I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps?


I am currently studying  answer on the Moore-Penrose pseudoinverse and the Euclidean norm by the user "Etienne dM". The first point of their answer proceeds as follows:  Let $x$ be $A^+y$.  Let me begin by the second point. For all $z$, we have: \begin{align} \lVert Az-b \rVert_2^2 &= \lVert Ax-b \rVert_2^2 + \lVert A(z-x) \rVert_2^2 + 2 (z-x)^TA^T(Ax-b)\\ & \geq  \lVert Ax-b \rVert_2^2 + 2 (z-x)^TA^T(Ax-b) \end{align} Moreover, because $(AA^+)^T = AA^+$, $$ A^T(Ax-b) = ((AA^+)A)^Tb - A^Tb = 0$$ Thus, we prove that for all $z$, $\rVert Az-b \lVert_2^2 \geq\rVert Ax-b \lVert_2^2$, that is to say $A^+b$ is as close as possible to $y$ in term of the Euclidian norm $\lVert Ax-b\rVert_2$.   I realise that $x = A^+ y$, but I don't understand how any of this implies that "$A^+ b$ is as close as possible to $y$ in terms of the Euclidean norm $\lVert Ax-b\rVert_2$". The way I see it is that we have 4 facts:  $\lVert Az - b \rVert_2^2 = \lVert Ax - b \rVert_2^2 + \lVert A(z - x) \rVert_2^2 + 2(z - x)^T A^T (Ax - b) \ge \lVert Ax - b \rVert_2^2 + 2(z - x)^T A^T (Ax - b)$;  Because $(AA^+)^T = AA^+$, $A^T(Ax - b) = ((AA^+)A)^T b - A^T b = 0$;  Singular value decomposition (SVD): $A^+ = VD^+U^T = V \Sigma^+ U^T$;  $x = A^+ y$.   Supposedly, these 4 facts together prove that "$A^+ b$ is as close as possible to $y$ in terms of the Euclidean norm $\lVert Ax-b\rVert_2$". However, I do not see how this is so.  answer by "Ben Grossmann" is supposed to show something similar. I can see how this answer is related to what "Etienne dM" did in their proof, but I do not see how it is the same. I suspect that I am lacking some assumed, fundamental knowledge that "Etienne dM" had in constructing this proof, and so I am unable to see how these 4 facts combine to prove what is claimed. I would greatly appreciate it if people would please take the time to carefully explain this to me.  related question is for the limit definition of pseudoinverse.

I am currently studying  answer on the Moore-Penrose pseudoinverse and the Euclidean norm by the user "Etienne dM". The first point of their answer proceeds as follows:  Let $x$ be $A^+y$.  Let me begin by the second point. For all $z$, we have: \begin{align} \lVert Az-b \rVert_2^2 &= \lVert Ax-b \rVert_2^2 + \lVert A(z-x) \rVert_2^2 + 2 (z-x)^TA^T(Ax-b)\\ & \geq  \lVert Ax-b \rVert_2^2 + 2 (z-x)^TA^T(Ax-b) \end{align} Moreover, because $(AA^+)^T = AA^+$, $$ A^T(Ax-b) = ((AA^+)A)^Tb - A^Tb = 0$$ Thus, we prove that for all $z$, $\rVert Az-b \lVert_2^2 \geq\rVert Ax-b \lVert_2^2$, that is to say $A^+b$ is as close as possible to $y$ in term of the Euclidian norm $\lVert Ax-b\rVert_2$.   I realise that $x = A^+ y$, but I don't understand how any of this implies that "$A^+ b$ is as close as possible to $y$ in terms of the Euclidean norm $\lVert Ax-b\rVert_2$". I would greatly appreciate it if people would please take the time to explain this to me.


Let $V$ be the vector space of $2 \times 2$ matrices over a field $F$. Let $A =  \begin{pmatrix} a & b \\ c & d \end{pmatrix} \in V$ and let $T : V \rightarrow V$ be the linear transformation defined by $T(X) = AX$. Compute $\det(T)$. Can any one tell me if the answer would simply be the determinant of $A$ and, if not, how would you go about solving this problem?

I've got the following question     Consider the linear operator of left multiplication by an $m \times m$ matrix $A$ on the vector space of all $m \times m$ matrices. Determine the trace and determinant of this operator.   I'm a bit stuck as to how to even begin, I know this is going to involve eigenvalues/vectors and that if $\lambda_1, \lambda_2, ... ,\lambda_m$ are the $m$ roots of the characteristic polynomial of an $m \times m$ matrix $A$, then:  $\det(A) = \lambda_1 ... \lambda_m$  and  $\text{trace}(A) = \lambda_1 + ... + \lambda_m$  But obviously not all $m \times m$ matrices have $m$ eigenvalues so I'm really stuck on this question.  Thanks!


Is it wrong or looked upon to acknowledge God on Master's thesis paper?

I saw that some theses acknowledgements thanks God, so are there any rules or suggestions about that? Is it ok to do it for believers or just don't mention your religious affiliation in a scientific work?


I don't understand the connection between generics and arrays.  I can create array reference with generic type:  private E[] elements; //GOOD   But can't create array object with generic type:  elements = new E[10]; //ERROR   But it works:  elements = (E[]) new Object[10]; //GOOD

Due to the implementation of Java generics, you can't have code like this:   public class GenSet<E> {     private E a[];      public GenSet() {         a = new E[INITIAL_ARRAY_LENGTH]; // error: generic array creation     } }   How can I implement this while maintaining type safety?  I saw a solution on the Java forums that goes like this:  import java.lang.reflect.Array;  class Stack<T> {     public Stack(Class<T> clazz, int capacity) {         array = (T[])Array.newInstance(clazz, capacity);     }      private final T[] array; }   But I really don't get what's going on.


I had learned the principle of least action.But I didn't get the motive behind taking the least action. Or why should the particle follow a path where it have a least action?

I'll be generous and say it might be reasonable to assume that nature would tend to minimize, or maybe even maximize, the integral over time of $T-V$.  Okay, fine.  You write down the action functional, require that it be a minimum (or maximum), and arrive at the Euler-Lagrange equations.  Great.  But now you want these Euler-Lagrange equations to not just be derivable from the Principle of Least Action, but you want it to be equivalent to the Principle of Least Action.  After thinking about it for awhile, you realize that this implies that the Principle of Least Action isn't really the Principle of Least Action at all:  it's the "Principle of Stationary Action".  Maybe this is just me, but as generous as I may be, I will not grant you that it is "natural" to assume that nature tends to choose the path that is stationary point of the action functional.  Not to mention, it isn't even obvious that there is such a path, or if there is one, that it is unique.  But the problems don't stop there.  Even if you grant the "Principle of Stationary Action" as fundamentally and universally true, you realize that not all the equations of motions that you would like to have are derivable from this if you restrict yourself to a Lagrangian of the form $T-V$.  As far as I can tell, from here it's a matter of playing around until you get a Lagrangian that produces the equations of motion you want.  From my (perhaps naive point of view), there is nothing at all particularly natural (although I will admit, it is quite useful) about the formulation of classical mechanics this way.  Of course, this wouldn't be such a big deal if these classical ideas stayed with the classical physics, but these ideas are absolutely fundamental to how we think about things as modern as quantum field theory.  Could someone please convince me that there is something natural about the choice of the Lagrangian formulation of classical mechanics (I don't mean in comparison with the Hamiltonian formulation; I mean period), and in fact, that it is so natural that we would not even dare abandon these ideas?


So I play rocket league on the ps4 and I am trying to get the sweet tooth. Now I've tried many different tutorials to get the car and still haven't gotten it. Can anyone tell me how to get it because I've tried every way people show on YouTube.

How do you get Sweeth Tooth's ice cream van (from Twisted Metal) in Rocket League?


I have created a T test in R and got the below output.  t.test(casein,mu=pw,alternative="greater")  ##  One Sample t-test ##  ## data:  casein ## t = 3.348, df = 11, p-value = 0.003251 ## alternative hypothesis: true mean is greater than 261.3099 ## 95 percent confidence interval: ##  290.1791      Inf ## sample estimates: ## mean of x  ## 323.5833    Here as you can see the P-value is 0.003, which is less than the significant value of 0.05. Hence shouldn't the alternative hypothesis be rejected in this case? How is true?

After taking a statistics course and then trying to help fellow students, I noticed one subject that inspires much head-desk banging is interpreting the results of statistical hypothesis tests.  It seems that students easily learn how to perform the calculations required by a given test but get hung up on interpreting the results.  Many computerized tools report test results in terms of "p values" or "t values".  How would you explain the following points to college students taking their first course in statistics:   What does a "p-value" mean in relation to the hypothesis being tested?  Are there cases when one should be looking for a high p-value or a low p-value? What is the relationship between a p-value and a t-value?


I need to know the answer to this question to find out why bees use hexagonal cells in hives. I know that a circle takes up the most area using the least perimeter, so bees would try to make shapes as close to a circle as possible to use the most space without wasting too much material on walls. However, bees don't use circles because using circles creates a lot of waste space between cells, so bees use a shape that can tile a plane without overlap. The shape that meets the conditions of having a lot of sides and being regular to look like a circle, and being able to tile a plane  is the hexagon, so bees use this in their hives. However, I want to know whether or not this is the polygon with the most sides that fits this requirement. I try to prove there is no bigger polygon like this. First, I note that an integer number of interior angles must meet at a site and add up to $360$ degrees to tile a plane. For example, squares can tiles a plane because they all have $90$ degree angles, and $4$ of these make $360$. All polygons have exterior angles adding up to $360$, so a polygon with $n$ sides has $\frac{360}n$ degrees per side. However, interior and exterior angles are supplementary, thus the interior angle of an $n$ side polygon measures $180- \frac{360}n$ degrees. Now, let's test whether this quantity divides $360$ degrees. We get $360 \over 180- \frac{360}n$, which simplifies down to $\frac {2n}{n-2}$. Now, I need to prove that $n=6$ is the biggest number such that this quanitity is an integer, but I am not sure how I would go about  doing that.

I read in several places, including Wikipedia, that a tessellation of the plane by a single, convex, $n-$sided polygon is not possible for $n\geq7$. I was not able to locate a proof, or a paper that discusses this. Maybe it is too trivial, but I am not able to figure it out myself.   So I would like to ask you for help. Where can I find a proof for this?  Also, I am interested in the mathematical background behind plane tiling (especially periodic), If you can suggest papers on the topic it would really help.


Given I have the number $50,000$ which is $70$% of $X$. How do I calculate what $X$ is without guessing.  Thanks

I have a database of prices that already have a 10% discount.  For example a product could be $100 after a 10% discount.  Is there a reusable formula I can use to determine what the original price was of all the 10% discounted prices in the database?  Edit: Thank you for the fast responses.  Is there any way to account for rounding errors?  A real example is a product with a discounted price of \$129.00  Using the X/.9 formula, I get \$143.33 as the original price, which does not actually work out.  To have had \$129.00 as the discount price, the original price would have needed to have been \$143.34.


Possible Duplicate:          I'm writing a report (in LaTeX) in cryptology and I have to work with very large numbers. I want those big numbers to be on multi-lines, I mean when I write my big number, and after compiling, LaTeX puts this big number on a single line, but we can only read the beginning of this number. How to print the big number on multi-lines automatically ? Is there a tag to use or something else? Thanks


In $F = kma$, why $k$ is taken to be unitless?  If $k$ is unitless and 1, then we have $F=ma$. This means (I guess) the physical quantity Force is product of different (from Force) physical quantities mass and acceleration. But doesn't that mean we are equating entities that are physically different? What is the basis for the choice of $k$ to be unitless.

It seems intuitive that $a\; \propto \frac{F}{m}$, as the greater the force that is applied on an object, the greater its acceleration will be. Inversely, the greater the mass of the object, the slower the acceleration will be.  However, when rewriting proportions as equations, you must introduce a constant of proportionality, and in this case of a direct proportion, if $a \propto \frac{F}{m}$ then when rewriting as an equation you will have $$a = k\cdot\frac{F}{m}$$  In order to get the standard formula $F = ma$ this constant must be $1$. However, how do we know that this is the case? How do we know that the constant isn't $2$ and the formula $F = \frac{1}{2}ma$, for instance?