Here is the problem: There are 100 doors and 100 people. The doors have two states (open/closed). All the doors are closed at first. Then the first person opens all the doors, the second person toggles the doors in multiples of 2 (e.g. door 2,4,6..). The third person toggles the doors in multiples of 3 (3,6,9...). This continues until person 100 toggles the door 100. So how many doors are open and how many are closed?  I understood this part that 1st person will open the door, second person will close the door, third person will open the door and so on.. But how to solve it?

I have a problem called "The Prison Problem" that I need to explain to my 9-year-old cousin. I would think that he has just started learning about divisors and perfect squares, and as such, I have a proposed solution. Any input from you guys would be welcome, as to what is the best way to go about this.  Problem:  There was a jail with 100 cells in it, all in a long row. The warden was feeling very jolly one night and told his assistant that he wanted to give all the prisoners a wonderful surprise. While they were sleeping, he wanted the assistant to unlock all the cells. This should be done, he told the assistant, by putting the key in each lock, turning it once. The assistant did this, then came back to report that the job was done. Meanwhile, however, the warden has second thoughts. "Maybe I shouldn't let all the prisoners free," he said. "Go back and leave the first cell open, but lock the second one (by putting the key in and turning it once). Then leave the third open, but lock the fourth, and continue in this way for the entire row." The assistant wasn't very surprised at this request as the warden often changed his mind. After finishing this task, the assistant returned, and again the warden had other thoughts. "Here's what I really want you to do," he said. "Go back down the row. Leave the first two cells as they are, and put your key in the third cell and turn it once. Then leave the fourth and fifth cells and turn the key in the sixth. Continue down the row this way." The assistant again did as instructed. Fortunately, the prisoners were still asleep. As a matter of fact, the assistant was getting pretty sleepy, but there was no chance for rest yet. The warden changed his mind again, and the assistant had to go back again and turn the lock in the fourth cell and in every fourth cell down the row. This continued all through the night, next turning the lock in every fifth cell, and then in every sixth, and on and on, until on the last trip, the assistant just had to turn the key in the hundredth cell. When the prisoners finally woke up, which ones could walk out of their cells?  Proposed solution:  Ten cells are left open after this process. Every cell that is a perfect square will remain open (1, 4, 9, 16, 25, 36, 49, 64, 81, and 100). If a number is not a perfect square, then it has an even number of divisors, therefore it will be "toggled" an even number of times and end up where it started (closed). Perfect squares have an odd number of divisors, so they will end up the opposite of where they started (open).


I have two files, GettysburgAddress.txt, where the Gettysburg Address is written, and GettysburgAddressCopy.txt, which is an empty text file that I'm supposed to fill in with the Gettysburg Address, each sentence, till its period, on a different line. So I thought of this   import java.io.PrintWriter;` import java.io.FileNotFoundException;v` import java.util.Scanner;` import java.io.File;  public class UltimateTextFileOutputDemo  {      public static void main(String[] args)     {         String writtenFileName = "C:\\Documents and Settings\\GettysburgAddressCopy.txt";         PrintWriter outputStream = null;         try         {             outputStream = new PrintWriter(writtenFileName);         }         catch (FileNotFoundException e)         {             System.out.println("Error opening the file" + writtenFileName);             System.exit(0);         }           String readFileName = "C:\\Documents and Settings\\GettysburgAddress.txt";         Scanner inputStream = null;         try         {             inputStream = new Scanner(new File(readFileName));         }         catch (FileNotFoundException e)         {             System.out.println("Error opening the file " +                             readFileName);            System.exit(0);         }         while (inputStream.hasNextLine())         {             inputStream.useDelimiter(".");            // setting the period as the delimiter of the read piece of text, I'm sure it gets a single, complete sentence             String line = inputStream.nextLine();             outputStream.println(line);         }         outputStream.close();         inputStream.close();          System.out.println("The Gettysburg Address was written to " + writtenFileName);      } }   When run, the program rightly creates the GettysburgAddressCopy.txt, if it doesn't exist yet, but it doesn't fill it with the speech. I realize the code naïvety is all in the three lines  inputStream.useDelimiter("."); String line = inputStream.nextLine(); outputStream.println(line);   but then, what's the right code to write? Many thanks for giving me the best tips you can.

It has always bothered me that the only way to copy a file in Java involves opening streams, declaring a buffer, reading in one file, looping through it, and writing it out to the other steam.  The web is littered with similar, yet still slightly different implementations of this type of solution.  Is there a better way that stays within the bounds of the Java language (meaning does not involve exec-ing OS specific commands)?  Perhaps in some reliable open source utility package, that would at least obscure this underlying implementation and provide a one line solution?


I was a victim of some serial upvoting, see the post, , on SE Raspberry Pi. Nothing particularly new or amazing in that, granted. However, during, and as a cause of, the serial upvoting, I was awarded the "Nice Question" bronze badge. The votes have, rightly, been removed by the system, but I still have the badge in my collection.  Here is a screen shot of my reputation changes, showing that the votes have been removed.        Here is a screenshot of the badge being awarded due to one of the serial upvotes.        Here you can see that I still have the badge awarded.    Shouldn't I be stripped of the badge, in the same way that I was stripped of the reputation, if it was awarded as a by product of someone's thoughtless upvoting?

user has serial up-voting reversed, but he still have badge Mortarboard.   Is it correct behavior of badges? I suppose it should be reversed too.  And will this 200 daily reputation (2012-03-20) score for the Epic, and Legendary badges?


I have the join condition as below    Select ct.payment,pm.order    from contract as ct   left join payment_order as pm   on ct.con_id=pm.id     Here the table payment_order is in another database 'payment'. How can i query this using dblink. please help.

I'm going to guess that the answer is "no" based on the below error message (and ), but is there anyway to perform a cross-database query using PostgreSQL?  databaseA=# select * from databaseB.public.someTableName; ERROR:  cross-database references are not implemented:  "databaseB.public.someTableName"   I'm working with some data that is partitioned across two databases although data is really shared between the two (userid columns in one database come from the users table in the other database). I have no idea why these are two separate databases instead of schema, but c'est la vie...


I am facing difficulty in sizing the PDF image being imported into the beamer slide presentation. This is because the original image generated in TeX has a lot of unused space. Please advise me how I should include the image. Using the document class standalone I get a compile time error. Perhaps a missing item.

I'm inserting an image with a simple:  \includegraphics[height=5cm]{filename.png}   This results in an image that maintains the aspect ratio, and so gives me something like 6cm width. I only really want the left side of the image though, and would like to crop it to 50% width. Is it possible to do this?  If possible, I'd like to do this in a portable way (i.e. something that other authors of this document won't have to install packages for, and something that works with a reasonably old version of pdflatex - our computers at work are in sore need of an upgrade).


Why does $x_0 + \sin(x_0) \approx \pi$ when computing this multiple times on the calculator?   So for any value of up to $\approx 6.25$, doing the following operation ($x_0 + \sin(x_0)$, then the newly obtained value (let's call it $x_1$) is replaced instead of $x_0$: $x_1 + \sin(x_1)$) many times leads to a value, which is very close to $\pi$.   However, when going above that value, this will result in roughly $3\pi$, $5\pi$, etc.  Could anyone please try to explain why the simple first calculation works?  EDIT: Thank you so much for your answers guys - through a combination of the many, I believe to now understand why!

One thing, I'm not a mathematician so please be patient. I am still in Algebra II Trig. Leading with that, why does  $$ x_0 = \sin 1, \space  x_1 = x_0 + \sin x_0, \space x_2 = x_1 + \sin x_1 ... $$ and after a while, $$ x = \pi $$  I know this to be true because I have evaluated this on my TI-84 and more deeply evaluated it with this program I made:   To $100000$ Iterations (which I believe is enough)   So what's the math behind it? Why does adding $\sin 1$ in this manner produce $\pi$? Why doesn't doing the same thing using $100$ produce $\pi$? For example,  $$\sin(1) = 0.841470...,\space \sin(1) + \sin(0.8414...), \sin(1) + \sin(0.841470...) + \sin(1.587095126...),\space ... $$ $$ = \pi$$  My question is different from the mentioned because my function is not taking the sin of a sin consecutively, but is this following function: $f(x) = x + \sin x$ and is not $f(x) = \sin x$ and therefore can exhibit different properties I need explained.


I am new to Android Development and I get a NullPointerException when trying to get a writable database. Here is the code:  Main Activity  public class MainActivity extends AppCompatActivity {      MyDatabase myDatabase;     SQLiteDatabase sqLiteDatabase;     EditText textOne;     EditText textTwo;     Context context;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         textOne = (EditText) findViewById(R.id.textOne);         textTwo = (EditText) findViewById(R.id.textTwo);      }      public void addInfo(View view) {         String name = textOne.getText().toString();         String address = textTwo.getText().toString();         myDatabase = new MyDatabase(context);         sqLiteDatabase = myDatabase.getWritableDatabase();         myDatabase.addData(name, address, sqLiteDatabase);         myDatabase.close();          textOne.setText("");         textTwo.setText("");      } }   My database code:  public class MyDatabase extends SQLiteOpenHelper {      private static final String DATABASE_NAME = "info.db";     private static final String TABLE_NAME = "Personal_Info";     private static final String NAME_COLUMN = "names";     private static final String ADDRESS_COLUMN = "address";     private static final String ROW_IDENTIFIER = "_id";     private static int DATABSE_VERSION = 1;     private static String query = "CREATE TABLE " + TABLE_NAME + "(" + ROW_IDENTIFIER + " INTEGER PRIMARY KEY AUTOINCREMENT, " + NAME_COLUMN + " TEXT, " + ADDRESS_COLUMN + " TEXT);";      public MyDatabase(Context context) {         super(context, DATABASE_NAME, null, DATABSE_VERSION);     }      @Override     public void onCreate(SQLiteDatabase db) {          try {             db.execSQL(query);         } catch (SQLException e) {             e.printStackTrace();         }      }      public void addData(String name, String address, SQLiteDatabase db) {          ContentValues contentValues = new ContentValues();         contentValues.put(NAME_COLUMN,name);         contentValues.put(ADDRESS_COLUMN,address);         db.insert(TABLE_NAME,null,contentValues);      }      @Override     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {          try {             db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME );         } catch (SQLException e) {             e.printStackTrace();         }          onCreate(db);     } }   The error is thrown on this line in MainActivity:  myDatabase = new MyDatabase(context);   All input is welcome.

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 was trying to install Moonlight, but following the commands didn't work.  Now I don't care about that any more, but my Software Center and Update Center kept on crashing.  I managed to get rid of them through the terminal, but reinstalling them is proving to be a problem I keep on running into.   Output from the terminal, which is as I think a piece of information left over from the attempt to install moonlight.   E: Type 'echo' is not known on line 2 in source list /etc/apt/sources.list.d/mono-xamarin.list E: The list of sources could not be read.   How to I get rid of this and reinstall my Software/Update Center?

Every once in a while I see users having issues to update due to errors like this:  E:Type 'ain' is not known on line 1 in source list /etc/apt/sources.list.d/some-ppa.list'   with varying types/line numbers/source list files (often after removing a PPA).  How can such an error be fixed?


Let $f:[a,b]\to\mathbb{R}$ be differentiable and $f'$ is continuous. Suppose $f(a)=f(b)=0$, show that  $$\max_{x\in[a,b]}|f'(x)|\geq\frac{4}{(b-a)^2}\int_a^b|f(x)|dx$$  My approach. For any $x$, by Taylor's theorem there is $\xi\in(a,x)$ s.t.  $$|f(x)|=|f(a)+f'(\xi)(x-a)|\leq\max_{x\in[a,b]}|f'(x)|(x-a)$$  Hence   $$\int_a^b |f(x)|dx\leq\max_{x\in[a,b]}|f'(x)|\int_a^bx-adx=\frac{(b-a)^2}{2}\max_{x\in[a,b]}|f'(x)|$$  I can only get this, and I don't know how to obtain $\frac{(b-a)^2}{4}$.

Let ${\rm f}:\left[a, b\right]\to\mathbb{R}$ be twice differentiable, and suppose   $$\lim_{x\to a^{+}} \frac{{\rm f}\left(x\right) - {\rm f}\left(a\right)}{x - a} = \lim_{x\to b^{-}}\frac{{\rm f}\left(x\right) - {\rm f}\left(b\right)}{x - b} =0 $$  Show that there exists $\xi \in \left(a, b\right)$ such that $\displaystyle{% \left\vert\vphantom{\Large A}\,{\rm f}''\left(\xi\right)\right\vert \geq \frac{4\left\vert\vphantom{\Large A}% \,{\rm f}\left(a\right) - {\rm f}\left(b\right)\right\vert} {\left(b - a\right)^{2}}}$.  I don't know how to start. Any hints ?.


i am using lg spirit it has 1 gb of ram,Android OS, v5.0.1 (Lollipop),Quad-core 1.3 GHz Cortex-A7 - H420,Mediatek MT6582 - H420,    Geo-tagging, touch focus, face detection.

With the announcement of the Ubuntu Phone OS I'd like to know what phone (and tablet) models are supported at this time.  Note from foss & Oli: We are making this the master question for all future "Will this work on <insert random tablet/phone/device here>?!" questions


I hold an Indian passport.  I'm travelling to Romania with a valid visa. I have a 5 hour layover at Munich international airport and 3 hour layover at Frankfurt international airport on the way back from Romania.  All the flights are of the same airline. Everywhere on the internet it says I need an airport transit visa.  However I met a person who said he didn't get a transit visa and still successfully went to Romania and back.

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


I know this point is apparently already treated in .  Being the second time I get downvoted with an answer containing the same amount of informations of another answer which get upvoted (and "heavily"), I began to think that the idea to be forced to explain a downvote is good.  But in an environment frequented also by poor-minded people (retaliators, friends-cluster and alike), and thus hostile, I understand downvoters prefer to stay secret, if they want, like explained in comments.  While this saves good downvoters from silly persons, on the other hand protects also bad downvoters and does not help improving answers, nor the OP to evaluate answers and decide which is better (supposing the OP is a good honest OP).  So the modified idea is: downvoters must give a reason, but this reason can be read only by the OP who made the question and it is likely interested in having more clues to evaluate the content of an answer (I think this is more important for beginners who sometimes choose as better answer one that seems to solve their problem, but indeed it will be a source of other problems, while other more correct answers are not taken into account since seen as "too complex"). (Extra idea: the OP can remove the downvote if the reason does not satisfy him/her, e.g. a reason containing just "a reason", just to fill it, is not a good reason... or maybe the OP can give a vote to the reason, and we could think about mechanisms where votes for the reasons influence someway the reputation...)  Of course, people with imagination can imagine evil scenarios where it is not desiderable th OPs have such information (e.g. there's no way to avoid they share it at least outside SO), but these scesarios are side by side with those where, say, upvoters vote up answers given by high-reputation guys (since they trust them) without reading the answer at all, and downvoters vote down since the answerer had commented "against" their comments or answers... (and many more, like clusters of friends voting each other answers)

I have been so annoyed recently by people who downvote my answers with no comments.  Usually it falls into one of two categories   The asker is asking a question that is inherently impossible or counter to the purpose of the thing they are asking about, like how do I use jQuery to (insert any horrific hack JavaScript coding practice jQuery is supposed to free us from).  The answerer responds with a reasoned description of why that might be misguided and offers an alternative approach.  Asker doesn't like that and downvotes the answer. A well meaning user posts a question, and Person A answers with a hastily written, insufficient, unreasoned, or maybe blatantly wrong answer.  Person B sees this answer, comments on why it might be insufficient, and then answers with a proper, well-reasoned answer.  Person A (presumably) sees this, gets angry, and downvotes Person B out of spite.   In both cases, of course, no helpful comment because all that would do is reveal how spiteful and/or vindictive the downvoting was.  I love Stack Overflow, but I am a busy person, so what little time I get to spend here, and what reputation I've earned, I've worked hard for, and I hope it adds to the value of the community at large ... but then someone comes along and chips away at my reputation out of spite, with no checks and balances?  If this goes on, what is my motivation for wanting to contribute to the community?  If I got downvoted with a reasonable comment, I would welcome that.  That shows me something I may not have thought of, gives me an opportunity to improve my answer, and again add to the community.  Downvoting with no comment serves no purpose but to degrade the community.  I propose that downvotes with no comment not detract from the poster's reputation.  And if that comment is something silly, and the comment gets flagged by someone else, the poster's reputation hit should be restored.  Thoughts?


I am new to Linux. I want to install webstorm.   I have the files and run the .sh file in terminal which launches the software.  However it seems I always have to do this, I cant run it without having to launch it via terminal and I don't have any entry for it when I search my programs.  Is there no way to permanently install it like all other software?

I have PhpStorm on my PC, to launch it I have to go to phpstorm/bin/ and launch phpstorm.sh, how can I pin this to launcher so that I dont have to go into folders every time?


Is it possible to sandbox a JavaScript function in C# code, execute it by passing in an argument such as an array, and return a result. No web browser involved here, this is not an Ajax or 'registerstartupscript' type of question.

just wondering if anyone has ever tried embedding and actually integrating any js engine into the .net environment. I could find and actually use (after a LOT of pain and effort, since it's pretty outdated and not quite finished) spidermonkey-dotnet project. Anyone with experience in this area? Engines like SquirrelFish, V8..   Not that I'm not satisfied with Mozilla's Spidermonkey (using it for Rails-like miniframework for custom components inside the core ASP.NET application), but I'd still love to explore a bit further with the options. The command-line solutions are not what I'd need, I cannot rely on anything else than CLR, I need to call methods from/to JavaScript/C# objects.  // c# class public class A {     public string Hello(string msg)     {         return msg + " whatewer";     } }  // js snippet var a = new A(); console.log(a.Hello('Call me')); // i have a console.log implemented, don't worry, it's not a client-side code :)   Just to clarify - I'm not trying to actually program the application itself in server-side javascript. It's used solely for writing custom user subapplications (can be seen as some sort of DSL). It's much easier (and safer) to allow normal people programming in js than C#.


Can I have some help with this?  The percentage is increasing... it's at 7% now.

I just started the LOL client and there's this 0% bar on the top left.  I hover over it and it says like 13562 MB left... I don't really know what that is.  Could anyone please clarify that?  Thanks...


In what cases is it appropriate to refer to unknown gender as she?

There are some questions on gender-neutral pronouns both  and on .  User Christine Letts :     In academia, there is currently a   movement toward using the feminine   pronoun at all times.   I wonder why that is. I came across several examples on papers I read, but the only one I can remember at the moment is a book: Seth Godin's . While some might not be comfortable labeling it as part of academia, it suits my point perfectly. Every time he refers to a person, he uses the feminine pronoun.  User Senseful  the following, potentially identifying affirmative action as the precursor for this trend.     I remember reading somewhere that it   was recommended to use the opposite of   what most people stereotype the   profession as. So, for example, when   talking about a chiropractor, you   would use "her", and when talking   about a secretary, you would use   "his".   So, where do you think this trend comes from?


The footer on the website says CC-BY-SA 3.0:    However the  page link to CC-BY-SA 4.0:    So which one is it now officially? V3 or V4?

In the footer it says:     site design / logo © 2018 Stack Exchange Inc; user contributions licensed under  with . rev 2018.8.7.31273   However, in the footer under Company > Legal > '6. Content Permissions, Restrictions, and Creative Commons Licensing' it instead doesn't specify which CC BY-SA licence we're releasing our content under. It also links to the CC BY-SA 4.0 license:     The CC-BY-SA Creative Commons license terms are explained in further detail by , but you should be aware that all Public Content you contribute is available for public copy and redistribution, and all such Public Content must have appropriate attribution.   Since  if subscriber content is only provided under 4.0, where the footer says 3.0 it can cause users to break the licences.  The footer under Area 51 also mentions that content is licensed under CC BY-SA 2.5.  Since it's not defined which version of the license the content is provided under, I also interpret it to potentially mean all the versions.    What license is subscriber content licensed under?


I recently installed ChrUbuntu onto my Acer C7 Chromebook. I tried running the update manager from the terminal and I keep getting the same message  E: Malformed line 60 in source list /etc/apt/sources.list (dist parse) E: The list of sources could not be read.   Someone help me, I'm so new to Ubuntu.

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


I was given $$ \frac{\int_0^{\pi/2}\sin^{\sqrt{2}+1}(x) \, dx}{  \int_0^{\pi/2}\sin^{\sqrt{2}-1}(x) \, dx} $$ How to evaluate this integral? Since denominator and numerator are different Integral substitution will fail , I tried with by part Integral but it lead to nowhere help?

I have this difficult integral to solve.  $$ \dfrac { \int_0^{\pi/2} (\sin x)^{\sqrt 2 + 1} dx} { \int_0^{\pi/2} (\sin x)^{\sqrt 2 - 1} dx} $$  Now my approach is this: split $(\sin x)^{\sqrt 2 + 1}$ and $(\sin x)^{\sqrt 2 - 1}$ as $(\sin x)^{\sqrt 2}.(\sin x)$ and $(\sin x)^{\sqrt 2 - 2}.(\sin x)$ respectively, and then apply parts. But that doesn't seem to lead anywhere. Hints please!  Edit:  This is what I did (showing just for the numerator)  $$ \int_0^{\pi/2} (\sin x)^{\sqrt 2 + 1} dx $$ $$ = \int_0^{\pi/2} (\sin x)^{\sqrt 2}.(\sin x) dx  $$ $$ = (-\cos x)(\sin x)^{\sqrt 2}\Bigg|_0^{\pi/2} + \int_0^{\pi/2}(\sin x)^{ \sqrt 2 - 1 }(\cos^2 x) dx  $$  (taking $ v = \sin x $ and $ u = (\sin x)^{\sqrt 2} $ in the $ \int uv $ formula)  $$ = \int_0^{\pi/2}\left( (\sin x)^{ \sqrt 2 - 1 } - (\sin x)^{ \sqrt 2 + 1 } \right) dx  $$  Similarly for the denominator. This does give a reduction formula but then I don't see how to really use it for finding the answer.


I need a suggestion! Tomorrow I am giving my phone to service centre for repairing my broken camera. I am feared that whether they can access my files or not? My phone is on android 10 out of the box and it is encrypted by default. I am going to reset my phone before giving it to the service centre. Is it possible to recover data on a encrypted phone?

I will have a few Android phones that I will have to let go.   I would like to make a proper clean wipe of the data, without no one being able to retrieve them, and do a factory reset.  I have read about the , encrypting the device before doing a factory reset, doing both, etc.  Since I am not an Android/adb guru, I would like to know if some of you would have some idea on how to achieve this with certainty.  I know "certainty" is a big word when it comes to proper data erasure on flash memory but still.  I have found some answers here and somewhere else, saying that encrypting and doing a factory reset on your Android device is enough, but I could not find a reliable source.  Just a few information that could be useful:   I'm running Linux as my OS and, therefore, I'm not looking for a Windows-based solution My devices are non-rooted and (almost) identical (Samsung A510F + 1 A510FD)


Numbers have each been encoded using RSA with a modulus of $m = p q = 496241$ (with $p$ and $q$ being primes) and encoding exponent of $218821$.  You are advised that $\{13631, 142703\}$ is a valid encoding–decoding pair for the same modulus, $m$.  $(a)$ Use this information to determine $\phi(m)$ for this modulus. (Using software to directly factorise m is not a valid option for doing this part.)  $de = 1 \pmod{\phi(m)}$, right? So in this case: $13631\times 142703 1 \pmod {\phi(m)}$. Am I right so far? How do I calculate what the mod is, and therefore what $\phi(m)$ is?   $(b)$ Verify your answer by determining the primes $p$ and $q$. Show how these combine to give both $m$ and $\phi(m)$.  $(c)$ Calculate the decoding exponent for $218821$, as encoding exponent, using the extended Euclidean algorithm. (Again, using software to directly obtain this is not a valid option, though you are welcome to use software to confirm your answer.)  $(d)$ For each of the $12$ numbers in your message, verify they have no prime factors in common with $m$. (It is OK to use software for this task, provided you have answered the previous part.)

I would like to factorise $496241$. I know the answer is $677 \times 733$. But I don't know how to get there.   Here is the full question:   "A message has been encoded using RSA with a modulus of $m = p q = 496241$ (with $p$ and $q$ being primes) and encoding exponent of $218821$.  You are advised that $\{13631, 142703\}$ is a valid encoding–decoding pair for the same modulus, $m$.  (a) Use this information to determine $\phi(m)$ for this modulus. (Using software to directly factorise $m$ is not a valid option for doing this part.)  (b) Verify your answer by determining the primes $p$ and $q$. Show how these combine to give both $m$ and $\phi(m)$."  I need it so I can solve (a), and it says I cannot use software to directly factorise m. So I guess pen and paper. But there are not tutorial online. Thanks


How do I calculate the sum of $$\sum _{n=2}^{\infty \:}\ln \left(1-\frac{1}{n^2}\right)$$ and prove that it is a convergent series?  I tried using comparison by choosing $a_n = -\frac{1}{n^2}$ and saying that if this is a convergent series, then my series is also a convergent one, since the $\lim _{n\to \infty }\left(\frac{\left(\ln\left(1-\frac{1}{n^2}\right)\right)}{-\frac{1}{n^2}}\right)$ would be $1$. I'm not sure if this is the correct way of doing this though, since I'm working with positive term series.

So I have this problem for midterm reviews:  $$\sum_{n=2}^\infty \ln\left(1-\frac{1}{n^2}\right)=\text{ ?}$$  I know that you can find the series form of a natural log, as shown here:  $$\ln\left(1-\frac{1}{n^2}\right)=-\sum_{k=2}^\infty \left(\frac{1}{n^{4k}}\right)\left(\frac{1}{2k}\right) $$  But the above doesn't seem to help very much since it results in two summation notations mushed together. Is there a somewhat nontedious way to go about this? Thanks! All help appreciated.


I've been looking for any case similar to mine and still haven't found one.  The story: I'm using arch linux, updated just last week, and it was working fine. I never configured auto-login, so I have to input my username and password everytime I boot. Today I decided to reboot, but when I tried to input my username I noticed a special character ^@ being added at regular intervals (aprox. once per second). I tried logging in while ignoring the character, and failed repeatedly, which led me to believe that the character was actually being added to my input, as if a key was stuck. I also tried changing to other tty but the problem persisted.  I didn't think it was a key stuck because to write that character I would need at least two keystrokes. I also booted using a bootable ubs stick and the problem did not appear, which proves it's not just a hardware problem.  Using the usb stick OS (and chroot), I updated with pacman -Syu, but it had no effect on the problem (note: I seem to have some messy dependencies with pandoc and haskel but I don't think they could have anything to do with this issue).  I turned it on and off a few times and noticed that the character started appearing in the boot sequence, right after the message of started udev Kernel Device Manager.   I never had anything like this happen to me, and it's very frustrating how it makes it completely impossible to even log in, so I can only work using the usb stick. I don't know how to even begin troubleshooting this, so any help is appreciated.

I recently noticed some weird behavior on my GNU/Linux machine. I've been trying to narrow it down but I am unsure where to go next. My setup uses the following:   i3 gdm arch systemd grub2 pulseaudio 4.13.3-1-ARCH   Here is how it manifests iself:   when trying to resize panes in i3 (alt+right click and hold) the action will be randomly canceled (happens on key presses) alt+dragging windows meets a similar fate booting to tty periodically adds ^@s to the login prompt, I'd estimate them to be ~0.5s intervals in tty I can see those being passed to vim when I open the command bar (:) using a pager like less in tty mode and searching with / will result in  (?) being spammed htop's search (/) is instantly canceled by the periodic keypress  holding a key and trying to have it be repeated (such as holding space) will stop the other occurrences from happening (e.g. only one or two happen) any tooltip (such as chrome tooltips) get instantly closed because of key presses   Here is what I have tried:   tried switching DE temporarily (gnome, cinnamon, xfce) tried killing programs one by one until I was left with a tty session and essentially systemd services + pulseaudio tried booting on an arch livecd - problem does not manifest  overriding grub2 with init=/bin/bash drops me into a shell where the problem does not manifest I have tried pressing all keys to verify it wasn't a hardware problem, however previous steps point to it not being hardware I have made a diff of dmesg, from the init=/bin/bash and the regular boot - the main difference seems to be systemd being started in the regular boot Made a diff of lsmod from init=/bin/bash and regular boot, tried to rmmod modules that seemed related   My system is up to date, I'm not quite sure what other steps I can do to track this down. Any other debugging tips?


I was reading some lore from the Forgotten Realms and saw something about higher level spell slots (10, 11 and 12) and them being sealed off for mortal beings.  So I was wondering if PCs know about spell levels as we know them, being able to sort them into tables based on spell level, knowing a fireball is a level 3 spell and magic missile a level 1.  I'm asking this because I want to make a character that is obsessed with 9+ level spells. But this would kinda fall flat without them being able to know the difference between a level 9 and level 10 spell.

Is there anything in RAW that supports spell level as a character concept, or alternatively that supports it as solely a player concept?  On the one hand, I see nothing that explicitly states that a character knows that there are spell levels. On the other hand, I don't see how a spellcaster could manage spell slots without knowing about spell levels.


I'm writing a paper to submit a conference.  However, I am having some problems fixing non-resolved references in latex.  \begin{figure*}[ht!]  \begin{subfigure}[b]{0.3\linewidth}      \includegraphics[width=1\linewidth]{fig/toy}      \vspace*{-1cm} % for cosmetic change      \label{fig:toynetwork_example}      \caption{A toy network}  \end{subfigure}%  \begin{subfigure}[b]{0.3\linewidth}      \includegraphics[width=1\linewidth]{fig/exampleProcedure13}      \vspace*{-1cm} % for cosmetic change      \label{fig:firstIterationFin}      \caption{After first iteration}  \end{subfigure}  \begin{subfigure}[b]{0.3\linewidth}      \includegraphics[width=1\linewidth]{fig/proposed_adjacency_matrix}      \vspace*{-0.4cm} % for cosmetic change      \label{fig:proposed_adjacency_matrix}      \caption{Adjacency matrix}  \end{subfigure}%  \begin{subfigure}[b]{0.3\linewidth}      \includegraphics[width=1\linewidth]{fig/proposed_influence_matrix}      \vspace*{-0.4cm} % for cosmetic change      \label{fig:proposed_influence_matrix}      \caption{Influence matrix}  \end{subfigure}%      \hspace*{0.2cm}  \vspace*{0.3cm} % for cosmetic change  \begin{subfigure}[b]{0.3\linewidth}      \includegraphics[width=1\linewidth]{fig/proposed_update_order}      \vspace*{-0.4cm} % for cosmetic change      \label{fig:proposed_update_order}      \caption{Update order}  \end{subfigure}%  \caption{Example network}  \label{fig:example_network_procedure}  \end{figure*}   The PDF file shows ?? rather than the reference.  Can you help me?

\documentclass{article} \usepackage{algorithm}  \begin{document} \setcounter{section}{54} \section{A section with no label} \begin{algorithm} \label{myalg} \caption{An algorithm with the label `myalg'.} \end{algorithm} Reference to myalg: \ref{myalg}. \end{document}   With this code, the reference givens 55 (the section number); if I move the label after the caption command, I get the correct reference (1).  Why should this be the case? I find it confusing: when thinking about an algorithm as an environment, you expect to be able to label it right after you began it. At the very least I would expect some kind of error or "??" to appear, rather than the previous environment or reference-able entity being used.


After I download the Ubuntu file how do I install on my desk top computer?  I am completely new to Ubuntu.

I would like to see a full how-to guide on how to install Ubuntu.


Is $\frac{\sigma(n)}{n}$ unbounded as n tends to infinity?  ($\sigma(n)$ is sum of proper divisors of $n$)

Robin's theorem says that if $$\sigma(n)<e^\gamma n\log\log n$$ holds for all $n>5040$, where $\sigma(n)$ is the sum of divisors of $n$, then the Riemann hypothesis is true, but if there are any counterexamples, then they are colossally abundant numbers, and there are infinitely many counterexamples.  Lagarias' theorem says $$\sigma(n)\leq H_n+e^{H_n}\log(H_n)$$ holding for all natural numbers $n$ is equivalent to the Riemann hypothesis, where $H_n$ is the $n$th harmonic number, the sum of the reciprocals of the first $n$ positive integers. It looks like Lagarias' inequality is sharper than Robin's, so any counterexamples to Robin's inequality must also be counterexamples to Lagarias'. Is known to be impossible for integers that aren't colossally abundant numbers or of some similar more general type to be exceptions to Lagarias' inequality?


I am trying to split the following dynamic url into several components like below. Url can be anything in the below format.  input:   https://www.test.com/directory/subdirectory/index.php?qry=4 or  https://www.test.com/directory/subdirectory/index.php or  https://www.test.com/directory/index.php?qry=4 or  https://www.test.com/directory/index.php or  https://www.test.com/index.php?qry=4 or  https://www.test.com/index.php or  https://www.test.com/   output:  $http_part = "https"; $root_url = "www.test.com"; $subdirectory = "directory/subdirectory";  // if not available blank should be returned $pagename = "index.php";   // if no page name is available default index.php $paramerts = "qry=4"; // if not available blank should be returned   I know i can use url parsing, but it doesnt in all the situation.   Any function is available by inputting the url which will return all these outputs ?

I need to build a function which parses the domain from a URL.  So, with   http://google.com/dhasjkdas/sadsdds/sdda/sdads.html   or  http://www.google.com/dhasjkdas/sadsdds/sdda/sdads.html  it should return google.com  with   http://google.co.uk/dhasjkdas/sadsdds/sdda/sdads.html  it should return google.co.uk.


Is it possible to convert a timestamp object in the format "2016-01-01" (year month day) into number of days from new years?   I'm getting my timestamp object by str(pandas.to_datetime('today')).split(" ")[0]  I would put code that I used to get it started but I don't even know where to begin except by making a dictionary for how many days are in each month and then calculating it the long way.  Is there something built in that I can use for this?

If I have two dates (ex. '8/18/2008' and '9/26/2008'), what is the best way to get the number of days between these two dates?


Show that if G is a group of odd order, then no $x\in G$ other than the   identity is conjugate to its inverse.   We can't have elements of order 2, since by Lagrange theorem this would mean we would have the subgroup generated by that element would have to divide the order of the group, but G is odd so this can't happen. Hence we can't have $x = x^{-1}$.  Now suppose there exists element $x\in G$ such that $x^{-1}=gxg^{-1}$ for some $g\in G$. Suppose that $y\in\operatorname{Orb}_G(x)$, so we have $y=qxq^{-1}$. Then $y^{-1}=qx^{-1}q^{-1}=qgxg^{-1}q^{-1}$, which implies that $y^{-1}\in\operatorname{Orb}_G(x)$.  So for each $y\in\operatorname{Orb}_G(x)$ we will also have $y^{-1}\in \operatorname{Orb}_G(x)$, so $\operatorname{Orb}_G(x)$ must be even, but by orbit-stabilizer theorem we have $|\operatorname{Orb}_G(x)|=[G:C_G(x)]$, where $C_G(i)$ is the centralizer of group $G$ for element $x$, but by Lagrange this must divide order of group $G$, which is odd, so this can't happen. Therefore our original assumption is wrong and we get our result.

Prove that if $G$ is a finite group of odd order, then no $x\in$$G$ , other than $x=1$, is conjugate to its inverse.   This question is from Advanced Modern Algebra (exer 2.79) by Joseph J. Rotman.  The hint states that if $x$ and $x^{-1}$ are conjugate, how many elements are in $x^{G}$?  What I know so far:   $\left\lvert x^{G}\right\rvert$ is odd (greater than 1, otherwise it's in the center) and is a divisor of |$G$| |Z($G$)| has a common factor (other than 1) with size of the orbit $\left\lvert x^{G}\right\rvert$ so that the center is not just the identity. This is from the class equation. The centralizer of $x$ has odd size and $\lvert C_{G}(x) \rvert \cdot \lvert x^{G}\rvert=\lvert G\rvert$   I don't see the implication of $x$ and its inverse being conjugate has other than their orbits having the same size and laying in the same conjugacy class.  Is the info I have useful? Any help would be appreciated.


I know that a Group G is defined as a set of elements with a binary operation with these three properties:  1) Associatively  2) Inverses Exist  3) Identity Exists  However there are many definitions such as the one found on wikipedia that say closure is also a property and what not. However I have seen some other things about groups and it said closure is not included as a property, mainly Harvard Abstract Algebra videos on Youtube.  I know that closure can come from those three properties sometimes, but not all the times. So my question is, is closure a property of a group?   I believe it is because there has been more information supporting it being one, then it not being included.

In some texts, there are three group axioms and in some there are four. The difference is that one of the axioms, the closure ($a,b\in G$ then $a*b \in G$) is omitted. Why is this so?


How can you custom the with of this col/field to adapt "Jun-Sep,2011" in just one line.    The MWE is copied from   \documentclass[11pt,a4paper,sans]{moderncv} \moderncvstyle{classic} % banking, casual, classic, empty, oldstyle options \moderncvcolor{blue}   % black, blue, green, grey, orange, purple, red options \usepackage[scale=0.85]{geometry} % default scale=0.7. height= scale * layoutheight  \firstname{John} \familyname{Doe} \title{R\'esum\'e}     % optional  \makeatletter \@ifpackageloaded{moderncvstyleclassic}{% \let\oldsection\section% \renewcommand{\section}[1]{\leavevmode\unskip\vspace*{-\baselineskip}\oldsection{#1}}% }{% } \makeatother  \begin{document} \makecvtitle \section{Professional Experience}     \cventry{Start--End, Year}{Intern}{Company}{Nowhere}{State}{     \begin{itemize}         \item Did something important here.     \end{itemize}}  % problem with vertical space------------------------------------------------- \section{Education}     \cventry{Jun-Sep, 2011}{Bachelor of Arts \LaTeX}{University of \LaTeX}{}{\textit{4.0/4.0}}{} %\vspace*{-6mm} %this will fix vertical spacing for \moderncvstyle{classic}, but create vertical spacing issues for other \moderncvstyle{xyz}.  % problem with vertical space ------------------------------------------------- \section{Skills}     \cvitem[-0.5em]{}{     \begin{itemize}         \item \LaTeX     \end{itemize}} %\vspace*{-6mm} %this will fix vertical spacing for \moderncvstyle{classic}, but create vertical spacing issues for other \moderncvstyle{xyz}.  \section{Languages}     \cvitem[-0.5em]{}{     \begin{itemize}         \item TeX-speak     \end{itemize}} % \cvitem{}{job description text here}  \end{document}

I am writing my CV using moderncv package, everythig is nice but I have a problem with \cventry command. I have something like this:   (it means 2010 - now)  I would want to have this in one line, rather than in two lines. I tried looking into the moderncv style files but with no success. What can I do to achieve the effect I want?


ls command shows the following :  a  code  controller.js  mani  sparat  this  ubuntu.gif   l command the shows similar to that :  a/  code/  controller.js  mani/  sparat/  this/  ubuntu.gif   What is difference between them ?

So, through typing several commands I've found that there's not only ls, but l and la too. There doesn't appear to be any man entries on Ubuntu 12.14. They all appear to do similar things with minor differences:  $ ls app        config     CONTRIBUTING.md  doc       Gemfile       Guardfile  LICENSE  MAINTENANCE.md  Procfile  Rakefile   script  tmp     VERSION CHANGELOG  config.ru  db               features  Gemfile.lock  lib        log      PROCESS.md      public    README.md  spec    vendor $ la app      CHANGELOG  config.ru        db   features  Gemfile       .git        Guardfile  LICENSE  MAINTENANCE.md  Procfile  Rakefile   .rspec  .secret     spec  .travis.yml  VERSION .bundle  config     CONTRIBUTING.md  doc  .foreman  Gemfile.lock  .gitignore  lib        log      PROCESS.md      public    README.md  script  .simplecov  tmp   vendor $ l app/       config/    CONTRIBUTING.md  doc/       Gemfile       Guardfile  LICENSE  MAINTENANCE.md  Procfile  Rakefile   script/  tmp/     VERSION CHANGELOG  config.ru  db/              features/  Gemfile.lock  lib/       log/     PROCESS.md      public/   README.md  spec/    vendor/   Just as a bit of trivia, are there more of these and what do they do? Is here any place to find this out? Unfortunately, google searching these commands gets ignored because they're so short.


Please suggest how can I get this type of straight lambda, refer image:

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?


Have been trying to login to my accounts and not able to as I have forgotten all emails, passwords, username and how I sign up as per name.  Have no idea estimated (date) when I signed up but has been years.  No memory of password or hint of one. Thinking of going into Hardware and Features and just deleting Google completely but don't know if that is the correct way and then open another account.

I have forgotten the password or username for my Google account, or I'm unable to access my account for other reasons.  How can I recover my account?  (This Q&A is meant as a general description for all Google and Gmail username/password questions. See: )


I was installing new LED lamps on my kitchen, which seemed to be functioning well. After turning off the lights, the newly installed lamps still had a dim light, that kept itself for quite long.  I've measured around 60VAC on the OFF switch for these lamps and 110VAC for the OFF switch attached to another lamp.  After lots of head scratching, I've tried to plug just one leg of the LED lamp into a plug hole, result on the picture below.     Why does this happen? How can I prevent it? Does it take a toll on my electrical bill?

I have recently purchased an IKEA LED bulb with G9 fittings, to replace a halogen one. .  The bulb is installed in a lamp with 3 other halogen G9s in a 3 + 1 configuration with a 3-state switch. "up" lights up all four bulbs, "down" lights up only the socket where the LED is.  I have found a strange behaviour. When the lamp's switch is in the off position, the LED bulb still emits a very dim light, whereas the halogen ones do not.  What is happenning here? Is this normal?  From my limited knowledge I would guess the lamp's circuit has some residual current which is not enough to light up the halogen bulbs, but makes the LED emit the dim light observed.


What are the best settings to photograph a sunset ?

I've been lucky on a few occasions, but I often struggle with capturing awesome sunsets. What can I do to remove the element of luck and get more consistent results?  Additionally, is it possible to tell if a sunset set is going to be particularly striking far enough in advance to plan to get to an  in time?


I'm running Xubuntu 20.10 on a MBA 2012. I wanted to use my GTK theme on a QT program, so I did a little searching and ended up with adding export QT_QPA_PLATFORMTHEME=gtk2 to my ~/.profile. That works, but whenever I log in, I get an error saying that the command # on line one can't be found. I assume this is a comment. I thought my line endings could be incorrect, so I opened VIM and changed them to UNIX, which didn't do anything. Coincidentally, Plank won't launch. Is there a better alternative to what I added to my ~/.profile, or is the error completely separate? Attached is the full ~/.profile. # ~/.profile: executed by the command interpreter for login shells. # This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login # exists. # see /usr/share/doc/bash/examples/startup-files for examples. # the files are located in the bash-doc package.  # the default umask is set in /etc/profile; for setting the umask # for ssh logins, install and configure the libpam-umask package. #umask 022  # if running bash if [ -n "$BASH_VERSION" ]; then     # include .bashrc if it exists     if [ -f "$HOME/.bashrc" ]; then     . "$HOME/.bashrc"     fi fi  # set PATH so it includes user's private bin if it exists if [ -d "$HOME/bin" ] ; then     PATH="$HOME/bin:$PATH" fi  # set PATH so it includes user's private bin if it exists if [ -d "$HOME/.local/bin" ] ; then     PATH="$HOME/.local/bin:$PATH" fi  # include Mycroft commands source ~/.profile_mycroft export QT_QPA_PLATFORMTHEME=gtk2

Ubuntu 18.04.4 (automatic upgrade from 18.04.3 just a few weeks ago) /bin/bash  After I log in from the Gnome shell, this message appears while the screen is just plain purple and before the desktop appears:  Error found when loading /home/hfinger/.profile:    /home/hfinger/.profile: line 1: #: command not found   /home/hfinger/.bashrc: line 1: syntax error near unexpected token '(' /home/hfinger/.bashrc: line 1: '# ~/.bashrc: executed by bash(1) for non-login shells.'    As a result the session will not be configured correctly.   You should fix the problem as soon as feasible.     Trouble is, what is the problem? I have searched AskUbuntu but no-one appears to have experienced this exact problem. I don't think it is the upgrade because it had been running for about a month before this problem appeared.    I have never touched these two files because I am quite happy to let the system create and configure them. Also, I try to keep Ubuntu as vanilla as possible to avoid having to restore settings after upgrading to a new release. For what it is worth, here are the first lines of each of these files:    .profile, line 1: # ~/.profile: executed by the command interpreter for login shells.   .bashrc, line 1: # ~/.bashrc: executed by bash(1) for non-login shells.     How do I need to fix these files? What additional information should I provide so that someone more knowledgeable than I can solve this dopey problem?


According to , I have 1003 total score in the regex tag, but  says I only have 999 (I only noticed this because I expected to see a gold badge to appear sooner or later). Given that the data the query is using is from a migration that happened many hours ago, shouldn't my user profile be updated by now? Has an update process failed to run?

From my , I learned that all tag related info on profile will be updated daily at UTC 03:00.  However, something is wrong here. It's now UTC 05:00+, but my tag number, say 93 (c++) is not updated against yesterday. I am pretty sure about this and I did earn some more points throughout the day. Sorry for not be able to capture the screenshot yesterday, but I did check this number 10 hours ago (which belongs to yesterday, also 93).  Is there a bug happening here? Or updating time different?    UPDATE: As of 24 Jan, the tags are still not updated with the proper values.  UPDATE2: Fixed around 25 Jan, UTC 03:00, at least for me.


Getting the following error in flow: An unhandled fault has occurred in this flow An unhandled fault has occurred while processing the flow. Please contact your system administrator for more information. Want to show actual trigger error (addError)in flow. Any suggestions would be appreciated. Thanks

I have an auto launched flow that I would like to just ignore the errors of if they occur. I currently have several fault connectors going to a dummy assignment. However I keep receiving error emails which is what I am trying to avoid.


I have a custom appliction, build in maven, with dependencies (more custom modules, and some other things like spring, apache commons and log4j).  How can I build an executable jar containing my application and all of it's dependencies? (I.e. what do I need to put in my pom.xml)  I am aware that it will be several megabytes in size, but I am looking for simplicity in building and executing my application.  And I would like to build via standard mvn clean install command.

I want to package my project in a single executable JAR for distribution.  How can I make a Maven project package all dependency JARs into my output JAR?


Sir/madam, How can I prove that the real line with semi open interval topology is separable but not second countable?   Thanks for your answers in advance

In  I give an example of a separable space that is not second-countable. What are other good examples?


How to create a tag for a very new and specific topic, which have a really small number of followers (all of them with low reputation on stackoverflow) in the optic of having a growing community that help each others by answering questions related to the topic ( inexistant in stackoverflow for the moment ) ?

Can someone please create the tag  on our site? We need to have it because        Foo is a recent/upcoming release / edition / model / episode of a popular, established OS / board game / bike brand / TV show   Foo is a hot new language / ingredient / game   we're currently using some other tag for questions about Foo, but it's causing ambiguity with a separate thing that's also named Foo      This is not a joke post. We get a lot of feature requests that ask for this or that tag to be created, and every time, a discussion ensues wherein people explain that there is no "tag creation department" and that community members create tags just by using them. I'm posting this "question" so that future requests of that type can be closed as a duplicate of this, saving time and eliminating redundant conversations for everyone involved.     See also:


Why is Arrays.setAll faster than Arrays.parallelSetAll in this case?  int[] array = new int[30000000]; Random rnd = new Random(); Arrays.parallelSetAll(array, i->rnd.nextInt(200));

How do you write (and run) a correct micro-benchmark in Java?  I'm looking for some code samples and comments illustrating various things to think about.  Example: Should the benchmark measure time/iteration or iterations/time, and why?  Related:


I'm new to QGIS. I have constituency maps in India and block maps from 2001 census. Each constituency usually consists of a few blocks, but in some cases, a part of a block may belong to one constituency and another part to a different constituency.  I want QGIS to spit out the block-constituency polygons. For example, if block X belongs to constituency 1 and 2, I want two different polygons- X1 and X2, to be the output (I also require the area of the resultant polygons).  I tried the intersect command in overlay operations, but it seems to me that only the blocks are being shown, not the potentially smaller 'polygons'.  Does anyone know if intersect is indeed the right command to use here?

I'm new to desktop GIS, and will try to ask while lacking the proper terms from the GIS lingo:  If QGIS was like Photoshop I would like to make a selection from one layer, and then match that selection to another layer to get the overlap between the two and create a new layer from this overlap.  Formulated in another way:  I want to select all land from each of the Norwegian municipalities. In the shapefile I have (you can download it here: ) municipality borders are found as "N5000_AdministrativGrense" (just the borders) and "N5000_AdministrativFlate" (borders and the land within each municipality). This data (borders and land per municipality) is too administrative - it includes ocean and we have a lot of fjords in Norway. I need the landmass minus ocean.  The landmass is found in the layer "N5000_ArealdekkeFlate" - or so it looks to a novice at least.   So - I want to find the intersection between the landmass (only land, no ocean) and municipality borders and make a new layer that is all municipalities without ocean.  I'm on a mac with QGIS as my installed tool. All tips, pointers and help is much appreciated.


What does $\int d(\sin x)$ actually mean?I mean to say when we have $\int f(x)dx$,we interpret it as the values $f(x)$ s are being multiplied by tiny $dx$ and are summed together.But how do we interpret the above from this point of view.Because there is $d(\sin x)$,not $dx$ and we take $\sin x$ in the Y axis.But in integration we take dx to be in the X axis.

What is the intuition/idea behind integration of a function with respect to another function? Say $$\int f(x)d(g(x)) \;\;\;\;\;?$$ or may be a more particular example $$\int x^2d(x^3)$$  My concern is not at the level of problem solving. To solve we could simply substitute $u=x^3$ and then $x^2=u^{2/3}$. My concern is rather about what meaning physical/geometrical does this impart?  ADDED if you ask what kind of meaning I seek, integration of a function w.r.t a variable gives the area under the curve and above x-axis.


Bonjour à tou.tes !  In my document (compiled with LuaLaTeX) the footnote counter restarts at 1 in each new chapter.  How do I do to number all footnotes continuously?  For example:  \documentclass[10pt,a4paper,openany,notitlepage]{book} \usepackage[bottom]{footmisc} \begin{document} Bonjour,  I'm trying\footnote{to use footnotes} hard ! \chapter{Chapter one} Here I am\footnote{out there} so lost with it ! This is not a footnote\footnote{yolo}. \chapter{Chapter 2} encore une\footnote{cirhose} \end{document}                       After compilation:

I would like footnote numbering to continue over pages and chapters. In my document it's reset every chapter. I'm using the report documentclass.


Is there a way to find out if $\sqrt 2$ exists in $F_p$ depending on p?

For which prime numbers $p$ is $2$ a quadratic residue modulo $p$.   I know that $2$ is a quadratic residue iff  $$2^{\frac{p-1}{2}} =1 \;  \bmod \;(p) $$ so  $$2^{p-1} =1 \;  \mod \; (p). $$ But I don't know what to do.


I understand that close reasons are supposed to be as  to the OP, whilst simultaneously not overburdening the person suggesting the close with too much navigation through multiple close reason pages.  So at present to suggest moving to another site I click:      Close > Off-topic > Belongs on another site > pick site > Sharepoint!   BUT (!) frequently the list does not contain the site most suited to migrate to (how many questions get migrated to meta nowadays out of interest?). Is it really too much to ask that people asking/answering questions on this site click a button marked other at the bottom of the site list to be taken to a full list of sites? If this is too much, can the migrate option be moved to the top level of close reasons so that this extra step does not obfuscate the close issue? So the process would become:       Close >  Belongs on another site > Pick site > Other site > The right site   I personally find  it incredibly frustrating that sites such as Cross Validated are not on the list, despite having ~23k questions whilst both Database Administrators which has been running for 6 months longer than Cross Validated, has only ~ 15k questions and Sharepoint (?!) also has around 26k questions (but has also been active for 6 months longer). I believe the off-topic list could be more flexible and that would give the best directions to OPs about where their question belongs.  I think that as there is a certain barrier to entry to get anything out of the site (the ability to ask a well-formed question or the knowledge to answer it) that this increased flexibility would in no way make the site worse. I do admit I come from the data domain side of things (so Cross Validated would be very useful to have) and users from other disciplines may vehemently disagree with me, but I hope I have made a clear case for offering increased flexibility in the site migration options.

I think there should be more Stack Exchange networks available when flagging a question to be migrated. For example I'd think that the following question:    ...would be a better fit on unix.stackexchange.com instead of Stack Overflow. But without the option to mark it so, I feel hesitant to mark it.


It seems to make sense that when an atom loses two protons, it would lose two electrons as well, but I don't actually know what happens.

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


I'm new to Illustrator, I was going to create some schematics with lines that have arrowhead in the middle, indicating the flow of liquid or gas.  I found the options to add arrowhead to either the start or the end of the line, but no option for the middle of the line.  I learned that an additional anchor point may help, but I don't know what to do next.  Any help is appreciated.

My question is simple. How to quickly create many arrowheads on a path using Adobe Illustrator? like this


I'm creating a java program to test if the given string is a comment or not and here's my code so far:  public class comment { public static void main(String args[]){     String[] com = new String[50];     Scanner scan = new Scanner(System.in);     int i = 2 ,a=0;     System.out.println("Enter comment");     com[i] = scan.nextLine();       if(com[0].equals("/")){          if(com[1].equals("/")){              System.out.println("comment");          }          else if (com[1].equals("*")){          for(i=2;i<=50; i++){              if(com[1].equals("*") && com[i+1].equals("/") ){                  System.out.println("comment");                  a=1;                  break;              }              else{                  continue;}}          if(a==0){System.out.println("not");}              }          else{System.out.println("not");          }          }       else{System.out.println("not");          }          }      }   I'm getting an error on this line of code:    if(com[0].equals("/"))   Error says: java.lang.NullPointerException  Any explanation on why is this occuring ?

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?


Is it possible to get a non-zero continuous function which has zero $L^{1}$ norm?

I wanna prove that   "if $f: \mathbb{R}^n \to \mathbb{R}$ is continuous and satisfies $f=0$ almost everywhere (in the sense of Lebesgue measure), then, $f=0$ everywhere."  I am confident that the statement is true, but stuck with the proof. Also, is the statement true if the domain $\mathbb{R}^n$ is restricted to $\Omega \subseteq \mathbb{R}^n$ that contains a neighborhood of the origin "$0$"?


I looked into the integrated manual of the xargs command, where the -I option is explained. And though I read the few lines repeatedly, I can not make any sense of it:     -I replace-str                 Replace  occurrences of replace-str in the initial-arguments with names read from standard input.  Also, un‐                 quoted blanks do not terminate input items; instead the separator is the newline character.  Implies -x  and                 -L 1.   Could you explain this to me with other words or give me a jump start by an example, which shows the importance of this option?

Can you explain what this command does:  files=(this_is_filename) for filename in ${files[@]}; do    ls -t1 ../htory/$filename* |     head -1 |     xargs -I fname cp -p fname ../htory2/somefile.CSV done   Especially this part of this command  xargs -I fname cp -p fname ../htory2/somefile.CSV


Why is radioactive or Carbon 14 dating only accurate for 60,000 years? In theory, there should always be at least SOME Carbon 14 in everything that was living at any given time. This is because no matter how many times you multiply something by 2, there will always be an answer (as long as the number is real). So why only to 60,000? Also, there are records of things existing for upwards of 4.28 billion years old (link:), if Carbon 14 dating is only accurate for 60,000 years, how do we know how old some of these microfossils are?

For an example, when they tried to get the carbon dating for presence of Aboriginal people in Australia they get to the number 40,000. But it could be much earlier. Why is that 40,000 years limit for carbon dating methods?


Suppose we have a triangle $\triangle ABC$ where the size of two angles are given: $\measuredangle B=15^\circ$ and $\measuredangle C=30^\circ$. We draw the median $AM$, so now what is the size of angle $\measuredangle AMC$?    The answer is $45^\circ$... Ask your friends to think on it for a while...  Find different solutions... Different proofs...  This is my solution/proof:    Continue $CA$, draw the ray $\vec{CA}$. Then draw $BN$, in which it is perpendicular to $\vec{CA}$.   $\triangle BCN$ is a $30^{\circ}-60^{\circ}-90^{\circ}$ triangle. as we know about this triangle. $BN=\frac12 BC$. So $BN=BM$. This tells us $\triangle ABN$, is isosceles, so $\measuredangle BMN=\measuredangle BNM=\frac{180^\circ-\measuredangle MBN}2=\frac{120^\circ}{2}=60^\circ$.    Now we know $\triangle BMN$ is equilateral.   Therefor $$MN=BN=BM\qquad(1)\\ \text{and }\measuredangle MBN=60^\circ\qquad{ }$$  By this, we get $\measuredangle CMN=180^\circ-\measuredangle BMN=180^\circ-60^\circ$,  $$\text{therefor }\measuredangle CMN=120^\circ\  (2)$$  $\measuredangle ABN=\measuredangle CBN-\measuredangle{CBA}=60^\circ-15^\circ=45^\circ$. So, the other angle of the right triangle $\triangle ABN$, i.e. $\measuredangle BAN$, should be $180^\circ-90^\circ-45^\circ=45^\circ{}^\dagger$, therefor $\triangle ABN$ is isosceles.  So we would have $AN=BN$. By (1) we get $MN=AN$, so $\triangle AMN$ is isosceles. Therefor $$\measuredangle AMN=\measuredangle MAN=\frac{180^\circ-\measuredangle ANM}2=\frac{180^\circ-30^\circ}2=75^\circ$$  Now, by using (2) we can find the size of $\measuredangle AMC$, which is  $$\angle AMC=\measuredangle CMN-\measuredangle AMN=120^\circ-75^\circ=45^\circ$$  ${}^\dagger$let's note that one may also know that $\measuredangle BAN$ is equal to $45^\circ$, since it is an external angle of the triangle  $\triangle ABC$

if $M$ is the midpoint of $BC$ then find the measure of $AMC$.    I tried to use the angles to find $AMC$ but I don't know how to use that $M$ is the midpoint of $BC$.


I'm making progress on building a portable light for my kayak. It will use 3 of following chips: . The battery will have to be portable so I'm planning to wire them in parallel.  I calculate 11.25 Ah needed so thinking to get the battery between:  12V, 14Ah 12V, 18Ah 12V, 35Ah  It is just going to depend on weight. Each light will be in an aluminum housing and only turned on under water. I've read about the troubles with overworking one LED when in parallel.  Can I put a resistor before each of the 3 lights and if so, can someone direct me there? Also, can I add switches to each light to conserve battery without overworking? That is, only turn on the lights I need?

Why can't you use a single resistor for a number of LEDs in parallel instead of one each?


Rotgarth the Orc Barbarian wants to break Anne the Purple Dragoon's halberd (he's probably tired of all those polearm master's AoO).  Looking up the , Rot can see that the halberd's shaft is:   Made of wood (AC 15)  Medium sized (some 8' long maybe?) Probably Resilient (18 HP) those cormyrian halberds are made to last. ...   Rot is really excited. The halberd shaft probably won't resist a couple blows from his greataxe, specially in his raging hands. Grummsh be glorified, but...  How does one goes about attacking an object in possession of an enemy?

I want to hit enemy's axe to break it. How this is properly played in D&D 5e? And what about shield or armor? Can I attack these items to break it?


In my wordpress project I have seen several times the use of do_action() function.   I don't know the working of this function, nor why we call it or where we use it?  Can someone please explain this to me?

This question might be wrong, I am not sure about it. Because I am not clear on this.  I know add_action it is used to to hook our function to the specified function. For example add_action('wp_head'.'myfunc'); now what ever code in myfunc will be executed in the wp_head(). This is clear but i am having doubt in do_action what it does?  I think it is used to create our own hook like already available hooks(wp_head,wp_footer,..etc) If i am correct can anyone show me a simple understandable answer with simple example.  I have tried the difference in internet but all are pointing to difference between add_action and add_filter. I don't want to go there because first i want to clarify this and then I’ll move there.  Can anybody help me?  EDIT after Question POST  function custom_register() {     echo '<script>jQuery(document).ready(function(){alert("Learning Hooks");});</script>';  } do_action('custom');  add_action('custom','custom_register');   I tried this in plugin but i didn't get the alert message.  But when i hook the same function with wp_head then it is working fine  /******************working****************/ add_action('wp_head','custom_register');


During the installation of Ubuntu 14.04, should I locate the "boot" partion after or before the "swap" partition, and what should I choose for the "boot" partition "primary or logical","at the beginning of the space or the end"?

A fair while ago (~ 2004) I was told to always create a separate partition for the boot directory.  And since then I always have.  But after reading a few questions about partitioning questions, I'm curious.  Do I still need a /boot partition?  Note:  If helpful, I'm dual booting (Win XP or 7) & Ubuntu 10.04.  I also have one partition (using ext2/3) which I use to share files between the two operating systems.


Four score and seven years ago, our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.   sbj: fathers         det: our vrb: brought forth         obj: nation                 det: a                 adj: new                 adj: *conceived*                         adv: <in>                                 obj: liberty                 cnj: and                 adj: *dedicated*                         adv: <to>                                 obj: proposition                                         det: the                                         adj: -that-                                                 sbj: men                                                         det: all                                                 vrb: are created                                                         cmp: equal         adv: <on>                 obj: continent                         det: this         adv: ...?   I'm working on this but can't wrap my head around the phrase in bold. I know that it's adverbial phrase of time, but what kind of phrase is it exactly? What part of speech is 'ago'? Sources don't seem to agree.

I was informed earlier today that the word ago is actually a postposition and the only one  of its kind in English. Is this correct? If so, why do  not use this classification and prefer to  instead?


I have an older MacBook Pro (Mid 2009) that cannot start and need to reinstall OS X from USB key or disc. With another MacBook I tried to download OS X El Capitan but is not available, only macOS Sierra, but my laptop is too old for macOS Sierra. How can download OS X El Capitan or older version of OS X?

This question might have been answered somewhere but have not been able to find it. So, I have a Mid-2009 MacBook Pro where I am still running OS X Yosemite since I forgot to update to OS X El Capitan when it was on the App Store before they changed it to macOS Sierra.  If I try to install macOS Sierra through the App Store it doesn't let me because it says that:  "This version of macOS 10.12 cannot be installed on this computer."    I started looking to see if I can find OS X El Capitan but there is no result through the Mac App Store nor Apple Developers site. So my last resort was through Google, where I found several options on where to download OS X El Capitan version 10.11.  So, my main question is if I download from these third party websites, can I install on top of my current OS like it is done through the App Store or do I have to do a clean install?  Would appreciate any help.


What is the significance of letter A in immunoglobulinA?  What are the significance of other letters D, M , G, E in diffeternt types of antibodies?

What is the exact meaning and full form of  IgM, IgG, IgA, etc? What is the rationale behind the names of the isotypes, if there is one? For example, what does "M" mean in IgM?


I have a laptop with a 128GB SSD in it and a 1,5TB HDD. I want to, when I install applications, that the apps get installed on my secondary hard drive. Is this possible in apt? What do I have to do?

When I install a software using apt-get it installs to default locations i.e to /usr/bin, /usr/lib, /usr/share and etc. For example when I install "Meld Diff Viewer" using  sudo apt-get install meld   and use whereis command to find its location, I get the following output  adnan@adnan-laptop:~$ whereis meld meld: /usr/bin/meld /usr/lib/meld /usr/share/meld /usr/share/man/man1/meld.1.gz   Is there any way to change the install location. Lets say if I want to install it in /usr/local/ can I do it using apt-get or aptitude? I know I can compile it from source and specify prefix option to configure script or make install but it would be better (and really easier) if I could do it using apt-get as I would be able to use uninstall, upgrade and other stuff that apt-get offers


What I want to do is to be able to copy either a layer or a group of layers into a new document which is sized to that layers exact dimensions. I find I can right click -> Duplicate -> New Document, but it is still sized the same as the original document. Is there any way to make it so that the new document will be sized precisely to fit the layer(s)? Thanks!

I am using Photoshop CS3 and I have been given a quite big PSD with a lot of elements in it. I want to select one of these groups in the layer pane and copy it to a new document, and this document needs to be the exact size of the group.  I have tried duplicating the group into a new document, but this results in a document with the same size as the original one.  I tried following this link  But I just can't control-c the layers I have selected?  My group is composed of text layer and one square layer with some effects in it (its a button).  Many thanks, felipe


I am trying to figure out whether my upload speed is limited by the WiFi speed (distance from the hotspot) or by the provider link.  The computer is pretty far from the wifi hotspot; I am getting 20Mbps down and 5Mbps up.  Is it possible that 5Mbps is result of a weaker antenna in the laptop and I might get a big boost by laying ethernet cable or is it more likely that this is just the speed limit that Verizon is giving us?

I have used dial-up and/or broadband services from many service providers (in India) and one thing I noted is that the upload bandwidth is lower than the download bandwidth.  Is there any reason for this?


On one of my host, i have /dev/mapper/centos-root reporting almost full (99%), here is output of df -h.  ==  [root@LA3QSSD02-20217 /]# df -h Filesystem                                       Size  Used Avail Use% Mounted on /dev/mapper/centos-root                           50G   50G  540M  99% / devtmpfs                                          63G     0   63G   0% /dev tmpfs                                             63G   64K   63G   1% /dev/shm tmpfs                                             63G   18M   63G   1% /run tmpfs                                             63G     0   63G   0% /sys/fs/cgroup /dev/sdy1                                        494M  210M  285M  43% /boot /dev/mapper/centos-home                          411G   33M  411G   1% /home /dev/mapper/datastore-datastore                   11T  548G  9.1T   6% /datastore  /dev/mapper/data-sdx                             734G   73M  734G   1% /data-sdx  /dev/mapper/data-sdf                             734G   73M  734G   1% /data-sdf /dev/mapper/data0                                734G   80M  734G   1% /data0  /dev/mapper/data-sdd                             734G   73M  734G   1% /data-sdd  /dev/mapper/data-sdt                             734G   73M  734G   1% /data-sdt  /dev/mapper/data-sdg                             734G   73M  734G   1% /data-sdg  /dev/mapper/data-sdu                             734G   73M  734G   1% /data-sdu  /dev/mapper/data-sdb                             734G   73M  734G   1% /data-sdb 10.253.48.21:/vol/eq1ag4rdtest01/kvm_ostemplates 3.0T  1.8T  1.3T  58% /vol/eq1ag4rdtest01/kvm_ostemplates tmpfs                                             13G     0   13G   0% /run/user/0   ==  Im unable to find out what is causing / to report full, here is some more details.  ++++  du -sh *  0       bin 229M    boot 5.5M    data0 0       data-sdb 0       data-sdc 0       data-sdd 0       data-sde 0       data-sdf 0       data-sdg 0       data-sdh 0       data-sdi 0       data-sdj 0       data-sdk 0       data-sdl 0       data-sdm 0       data-sdn 0       data-sdo 0       data-sdp 0       data-sdq 0       data-sdr 0       data-sds 0       data-sdt 0       data-sdu 0       data-sdv 0       data-sdw 0       data-sdx 698G    datastore 152K    dev 24M     etc 320K    home 0       lib 0       lib64 0       media 0       mnt 171M    opt 0       proc 160M    root 115M    run 0       sbin 20K     sharedstore 0       srv 0       sys 40K     tmp 2.6G    usr 1.8G    var 1.7T    vol   +++++  Please help me in find out what is consuming space on / and how to free it.   Thanks  Regards Aun

I've tried to deal with this for days now with no luck. In this forum and also in other ones I can see a lot of discussion about this but none of the solutions have worked for me.  My current situation is that I've got some GBs "missing" that I can't free or find anywhere. I guess this is some kind of problem like memory leaks that only get fixed when rebooting, but I just would like to ask if someone has a better idea because there are currently a few customers on that server.  Here are some of the commands I've seen in other threads and my particular outputs:  df -h  Filesystem            Size  Used Avail Use% Mounted on /dev/sda1              19G   16G  1.8G  90% / tmpfs                 384M     0  384M   0% /lib/init/rw udev                   10M  1.2M  8.9M  12% /dev tmpfs                 384M     0  384M   0% /dev/shm   du -Pshx /* 2>/dev/null  4.8M    /bin 27M /boot 0   /cdrom 1.2M    /dev 8.8M    /emul 504M    /etc 4.0K    /grubconf 88K /home 60K /images 0   /initrd.img 147M    /lib 0   /lib32 0   /lib64 16K /lost+found 12K /media 4.0K    /mnt 4.4M    /opt 777M    /proc 57M /root 4.7M    /sbin 4.0K    /selinux 4.0K    /srv 0   /sys 4.0K    /tmp 332M    /usr 471M    /var 0   /vmlinuz   lsof +L1  (no output)   lsof | grep -i delete  (no output)   find / -size +50000 -exec ls -lah {} +;  -r-------- 1 root    root 777M 2015-07-21 06:19 /proc/kcore -rw------- 1 root    root  64M 2015-07-09 03:31 /sys/devices/pci0000:00/0000:00:06.0/0000:01:04.0/resource0 -rw-r----- 1 root    adm   49M 2015-07-21 06:19 /var/log/auth.log -rw-r----- 1 root    adm  174M 2015-07-19 06:25 /var/log/auth.log.1 -rw-rw---- 1 control mail 100M 2015-07-21 06:00 /var/mail/control   If you make the maths from du, for example, you get a few GBs, but nothing close to 16GB.  / is ext3.  OS is Debian 6.0  is there anything am I missing here?


Many theories use something called energy to explain reason behind certain phenomenon, but I have not been able to grasp the idea of energy. Maybe it is because I have grown in a society where the word energy has a completely different meaning, I don't really care about that though.   When I started studying about energy, I got acquainted to a physical quantity called Work, which is defined as $W = F . s$. I never really understood why this quantity was defined. And moving on, I got to know that "Energy is the ability of a system to do work". After reading this relationship, I certainly didn't have any sense, any reason behind this relationship between energy and work. I simple mechanics, I always thought that if an object has energy, it can provide a force. But never understood why we say that "if an object has energy, then it can provide not just force, but $F . s$ , which is work". So my first question is: Why have we defined work to know what energy is? And why only $W = F . s$?  Then, when I accepted this unusual fact(to me atleast), I encountered the equation $E = mc^2$, or mass-energy equivalence. I have read many resources stating the mass can be converted to energy and vice-versa (even my book uses this statement), which seems highly against my intuitive sense of what energy is.  I know this question has been asked at Phys. SE previously, I have also read the answer to it. But still, there is a confusion in my mind as to what energy is.  Before asking my main question, I would like to share my thoughts as to what energy seems to me. When I think of energy, I think that if an object has energy, it can provide a force. That's it. What else it can do, because all forms of energy that we have, whether its Kinetic, Potential, Electric, even Heat(in which particles vibrate and thus exert a force on near particles), all of them exert a force.   I also read an answer on Phys. SE regarding this question, in which an answerer put on the views of Feynman, which stated that "energy is something that is conserved, it is a numerical value that remains constant, no matter what process has occurred. It is a law of nature".   So my final question: With all these confusions regarding what is energy, why do we use Work to define energy Mathematically(like energy has unit Joule, the same unit as work)? And why are my thoughts regarding energy are not true, even when we encounter forces with most of the energies? Or even simply, not including any mathematics, what is the idea behind energy?

The topic which haunted me for two years until I gave up on it. But now I am doing engineering and this topic suddenly popped out of my textbook from nowhere. I seriously need to understand this topic because I wasn't able to do so in the past. I have read many book on 'energy' and it came to nothing. Maybe just because the many books I have read all said 'energy' is something which doesn't 'exist'! It is 'abstract'! It is just a number which represents the state or orientation of a system. But then I see so many examples that 'uses' energy to do 'work'. But the question here is that if anything doesn't exist in this universe, then how can the same thing be used to do something that exist?  My problem is that I didn't understood the topic 'energy' and all the other topics related to it (work, power etc.)


We may use the verb 'contain' in a passive sentence? Question is, how? To me, the verb 'contain' is kind of INTRANSITIVE since it presents a state, not an action i.e. there is no working force (agent) in the sentence made with 'contain'.  Look:  The room has a few chairs. (can't be changed into passive)  The room contains a few chairs. What will be passive?  A few chairs are contained by the room.  OR  A few chairs are contained in the room.  OR  A few chairs are contained within the room.

The bottle contains two liters.   How do I convert it to "passive voice"? I think it should be:     Two liters are/is contained in the bottle.   What are your remarks?  Is it possible to make it "passive"?


I am running into an issues with locating index  In SSMS, if I expand Users>Indexes, I do not see an index named "_dta_index_Users_5_1466188719_88410000_K1_K6_K2_7_10_11"  But I can see a statistics created for it.  Also when I search for indexes on "Users" by running this query   SELECT index_id, name FROM sys.indexes WHERE object_id = OBJECT_ID('Users')  It appears in the result "_dta_index_Users_5_1466188719_88410000_K1_K6_K2_7_10_11"  So the question is why I cannot see this index in SSMS? The index is not disabled and not user created since all our indexes start with IX_USERS_XXX  Any suggestions.  Thanks!

I was analyzing a query using "Database Engine Tuning Advisor". During this time the database started to get blocking, long running queries and ended by restarted the instance. When I checked after that I found a few drop index commands had been executed.  drop index [dbo].[Profile].[_dta_index_Profile_7_1563152614__K15_K1]   Why did this happen? The query I was tuning was not on profile table!  How can I check if this index was already in the system before or was created during the analysis?


I just downloaded the new version of QGIS (2.18.11) and I can't find the option to clip or union with only selected features    Typically, there was a selection where you could choose only the selected layers.

what im doing is making a fixed distance buffer and it's working splendidly but i need the buffer to be created over certain selected areas not the entire layer, and at the creation wizard is only offers the the option of selecting the entire layer, and i need some areas within that layer to have a different buffer and some none at all.  is there a way around that?


Is this usage correct:  The Tim Smith show takes listeners through Tim's day to day life as a broadcasting legend cum podcaster.  Are the dashes "-" necessary?  and is the broadcasting legend too much?  Should it only be Noun-cum-noun?    Thanks.

I'm talking about the Latin cum, which I've seen used conjunctively, as in A-cum-B.  What does it mean, and how do you use it?


She had never attacked him or offered any violence towards him in any way. Yet he stalked her throughout the bowels of the ship intent on killing her as she did her best to avoid him and play hamster in the ducting. This has always bugged me as it seems to go against Hulk's established rage nature. What was it about her that pissed him off?

In the Avengers movie, when      Bruce Banner is on the helicarrier, he becomes angry and transforms into the Hulk. Black Widow happens to be next to him and even though both are on same team, he attacks her and then Thor.  He becomes hostile to everyone on the ship.  But later on, in the fight against Chitauri troops, Hulk is very comfortably self-controlled.    Why is that?    The only thing I could think of is that it has been many days (a year?) since the Hulk had gotten angry, so he couldn't control himself.    But that's lame to be so puny when Bruce Banner was compared to Stephen Hawking in intelligence.


I have an iPhone X and an iPad Pro, both running iOS 11. I notice, when streaming a YouTube video in iOS Safari, the video resolution is limited to a maximum of 720p.  For e.g., when watching  video on Safari on macOS, I am able to stream it in the maximum available resolution i.e. 1080p. But in Safari on iOS, the output is limited to a maximum of 720p.  Is this behaviour configurable in YouTube settings or Safari? I notice, the same video can be played back at full resolution in the Videos app in iOS, when downloading it on a Mac and transferring it on iOS device.  I do not wish to use the YouTube app for iOS.

I just got my first iPhone. There’s an issue with connecting to the App Store, so I’m watching videos on youtube.com in Safari. I’ve noticed that the videos are low-res. I don’t see the setting to turn on HD video sources. (I’m connected to my WLAN.)  Is it not possible to view HD videos on YouTube in Safari?


A computer that doesn't get used much needed updates the other day but it seems to be missing an admin account. I tried to activate it through cmd but since the one account on there is a standard user, it does not have the privileges to execute the commands to do this. I've also tried starting the pc in safe mode with cmd and it pulls up a standard user cmd every time. Any ideas?

I accidentally disabled my admin account.  After I login to another account I found I can not get admin rights, because all admin accounts on my computer are disabled.  I clicked on 'run as administrator' but only see a smart card choice (all the admin accounts are disabled so no choice provided)    I don't want to re-install my OS, help!    Details:  I have account A on my computer.    I got a new computer so I want to give the old one to my mother.    Creating a new user account B for her and disable account A.    Logout and restart.    Successfully login B, now I found I could not get admin rights because no account choice is provided.    More informations about my machine:  OS is Windows 10 and my admin account is a Microsoft Account.  I have an arch-linux installed on my computer and dual-boot it using GRUB, so maybe I can not use safe mode.


I'm not sure what day I last checked my inbox, but definitely not 17 May 2015. The email was sent to me 4 hours ago.

I am subscribed to get my unread inbox items every 3 hours. It's working well, but today I noticed something quite weird:    For sake of future search, adding the text:  The following item was added to your Stack Exchange global inbox since you last checked it on 2015-05-18  But that's just not true, I checked my inbox yesterday. Not 7 months ago. Can it be fixed, or did I miss something? Even going to my  did not "fix" this, got today another email with the same date as yesterday.


Suppose $L/K$ is not separable. Does this imply that there is an $a\in L$ such that $a^p\in K$ but $a\not\in K$? I know that the characteristic of the fields must necessarily be $p>0$. By definition, there must be some $a\in L$ that is inseparable; that is, it must have a minimal polynomial that has multiple roots in a field extension. Equivalently, its derivative must be $0$. Where to go from here?

Assume $K/F$ is an inseparable extension. Is it necessary that K contains an element $u \notin F$ that is purely inseparable over $F$?  I also posted in MO.


How do I open multiple Excel 2010 workbooks as separate files.  I do not want to have to toggle between the two or more I want to use on split screen.

When I have Excel running and I double click an Excel file in Windows explorer, I'd like it to launch in a new window by default so that I can move documents to separate monitors. Is there any way to get this behavior?


I am new to Python, and am trying to write a script that would upload a geodatabase to AGOL at a scheduled interval. However, the 32 bit distribution of Python cannot handle the file size (over 1 MB), even when the multipart parameter of addItem (using ArcREST) is set to true. Through some investigation, I've learned that this is a limitation of Python32, and to do what I'd like to do I need the 64 bit version. I was trying to avoid having multiple installs of Python (as I said, I'm new to it, so the less complication, the better), but if I remove Python as it was installed with ArcGIS, I lose Arcpy, which I also need. So, my question is, does anyone know of a solution to this issue, or am I stuck dealing with multiple Python installs?

I am trying to install 64-bit processing to ArcGIS 10.2, but the ESRI .  One similar question on this exchange  that shows an option to include this, but my setup installation program (which I downloaded) does not show this installation window, but instead goes straight to selecting features to install as shown below.  I can't find any other documentation for running 64-bit geoprocessing on ArcGIS version 10.2.  Can anyone show me how to do this? or is it best to just try to install the service pack 1 version of it?


I have a Dell xps 13 and I installed Ubuntu 16.04. It installed the broadcom drivers but it doesn't work. For me it's not possible to connect to the internet via cable. Is there any working solution, how I could possibly get it work.  It was working with Ubuntu 14.04. At some point, I don't know why, it stopped showing up wifi networks and didn't connect. So I fresh installed Ubuntu 16.04. But the problem didn't diminish.   At this point, I don't know what to do. I downloaded kernels and drivers and tried reinstalling, but it's still the same. The solutions on the internet I found, are not working for me.   Is there anyone, who could lead me to the right direction. I don't know where to begin.  Thx a lot  Output of lspci -knn | grep Net -A2:      02:00.0 Network controller [0280]: Broadcom Corporation BCM4352 802.11ac    Wireless Network Adapter [14e4:43b1] (rev 03) Subsystem: Dell BCM4352 802.11ac Wireless Network Adapter [1028:0019] Kernel driver in use: bcma-pci-bridge Kernel modules: bcma   I deactivated secure boot in the bios and that solved the problem.

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


How do you delete one unwanted entry in Autocomplete in Microsoft Edge?  This question has NOT been correctly answered yet.

How do I delete an unwanted entry in AutoComplete in Microsoft Edge?  I have tried everything including highlighting with the down arrows and nothing works.


I currently have a VPS with apache, php and mysql running on it (got other stuff too, but they arent related to the web server). It has 8gb ram, 4 core intel atom (dont know the clock speed) and 100gb disk space. This has run fine for a while, but im hitting limits with the processing speed and disk space. I have maxed this server package out so i have to move somewhere else. The concern i have at the moment is everything is currently running off the 1 CPU. When a request is made the 1 CPU has to handle everything. Fine on a small scale, but im starting to hit limits and i need to decide where to go from here. I have 2 solutions and i dont know which is the best long term solution. I want to make this server change now and be well setup for the future. I know cloud is good and all for addon, but i need to know what i should do to best deal with my concerns.   Option 1) Upgrade to a fully dedicated server. Brings me from 8gb ram to 32gb, atom CPU to Intel  Xeon D D-1520 (4 core, 2,2ghz) and 4TB storage. This is great, but expensive and it sticks to the same model i have now where everything is running off the one machine.   Option 2) Fragment the system so that mysql is on its own server with 100% of the computers resources and then have a separate file system that contains all of the files. This way when a reqest is made 1 server can handle all of the files and the other deal with the sql. My concern here is that the fragmentation will mean longer request times. calling localhost is a lot faster than an external http request.   What is the best direction for me to go?

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?