Matrices $B$ that commute with every matrix commuting with $A$

There have been many questions in the vein of this one, but I can't find one that answers it specifically.     Suppose $A,B\in M_n(\mathbb C)$ are two matrices such that, for any other matrix $C\in M_n(\mathbb C)$, $$AC=CA\implies BC=CB.$$ Prove that $B=p(A)$ for a polynomial $p\in\mathbb C[t]$.    Nothing is assumed about $A$ being diagonalisable or having distinct eigenvalues or being invertible.  Edit: after further work, this might not actually be true. If it's not, a counterexample would be great.


Difference between server JRE and client JRE

I was going through server jre, when i extracted serverjre tar.gz , it gave me jdk folder. why does serverJRE gives JDK like folder. There is JRE folder inside serverJRE also. So which one to use, whole serverJRE or just JRE folder which is inside serverJRE. Also contents of JRE inside serverJRE is same as JRE inside JDK.   I am not understanding the difference.


Where to find missing essential tools for Airgeddon?

First time Ubuntu user here. My airgeddon says I'm missing essential tools like iw, airmon-ng, airodump-ng, john, sslstrip and a bunch of other stuff. Where can I find and download these tools?


Lens recommendation for landscape photography with Canon 7D Mark II

I am all new to photography and about 3 weeks ago, I bought a Canon 7D Mark II body.  Up to now, I have been using a Canon 18-135 STM lens, which I borrowed from my friend.  I am thinking about buying a lens now, and since I mostly take landscape photos, I am thinking about buying a wide/normal angel prime lens.  So here are my criteria for the lens:   I need sharp images It should be wide, since I take photos of large scenes I take pictures at night or low light too   So, I really need your suggestions.  And here is what I came up with:   Canon EF 50mm f1.8 II Canon EF 50mm f1.8 STM Canon EF-S 24mm f2.8 STM Canon EF 40mm f2.8 STM   The fact that my camera has a crop factor of 1.6 pushes me more toward the latter two ones.


It's a high school level question which we can't seem to solve. Here it is:      Given $2$ lines, one of the length of the hypotenuse and the other with the length of the sum of the $2$ legs, construct with straightedge and compass the corresponding right triangle   I didn't make much progress. It seems that there's a theorem or a few basic facts about right triangles that I'm missing. What path do you suggest I take?  Thanks for your help.


I've got two tables conatining geometry: 1 containing big polygon's (regions, srid=4326) and another containing smaller polygon's (pand, srid=28992, containg ~9.9milion rows)  By using one of the big polygons, I want to find all the smaller polygons withing the bigger polygon. In the end I want the result set to be grouped by a column. But now I just want to count the number of rows (=number of objects within the big region)  This is the query I use at the moment:  WITH regio AS (  SELECT ST_Transform(the_geom,28992) as the_geom                   FROM public.regions WHERE gid = 622               ) SELECT    count(*) AS count FROM public.smaller AS p WHERE     ST_Within ( p.geovlak,                  (SELECT the_geom FROM regio)               )   But somehow this query takes ages to complete. This is the Queryplan:  Aggregate  (cost=3018553.41..3018553.42 rows=1 width=0)   CTE regio     ->  Index Scan using regions_prim_key_gid2 on regions  (cost=0.28..8.29 rows=1 width=1458)           Index Cond: (gid = 622)   InitPlan 2 (returns $1)     ->  CTE Scan on regio  (cost=0.00..0.02 rows=1 width=32)     ->  Seq Scan on smaller p  (cost=0.00..3010265.32 rows=3311910 width=0)         Filter: st_within(geovlak, $1)   I'm no expert in reading these queryplans; but the second to last row says there are ~3.3 rows instead of the ~9.9. So there is already some filtering in place. But 1 - what filtering is this? And 2 - I can't figure out where the problem in this query lies.  When changing the count(*) to a * and limit the result to 10; the query takes 99seconds to run, so that's also not fast enough. I can understand it takes some time, but it is still running :(  Spatial indexes:     CREATE INDEX smaller_geom_idx   ON smaller   USING gist   (geovlak);


The script, which will take IP from the file etc/hosts

I write script, but this does not work. I need the script, which will take IP from the file etc/hosts. How to do it?  Script: (This does not work)  host=www.example.com  ip=$(getent hosts "$host" | awk '{ print $1}')  echo $ip


Accessing constant values from an Apache Velocity template?

Is it possible to access a constant value (i.e. a public static final variable defined in a Java class) from a Velocity template?  I would like to be able to write something like this:  #if ($a lt Long.MAX_VALUE)   but this is apparently not the right syntax.


I have installed Linux Mint and now I want to change it to Ubuntu but I have a lot of apps and information on it.  Is there any way to get Ubuntu without losing data? Or how to back up my information and apps, then install a fresh Ubuntu and copy the backup on it?


Barr's body is a spiral X chromosome. If I'm not mistaken, one random chromosome (a healthy woman) is inactivated in each cell. Which X chromosome is inactivated in a given cell is random. I've heard the example of a tricolor cat. The patched coloring is caused by the fact that  cells responsible for the color of each patch contain another inactivated X chromosome.   But what if a girl is a carrier of the Daltonism gene, why isn't she sick if a chromosome with this gene can be inactivated in some cells?


Passing a list of parameters into a Python function

how would I pass an unknown number of parameters into a function? I have a function defined in the following way  def func(x, *p): return ...   I'm trying to pass in a list of values to use as parameters. I tried using a list and a tuple but the function always returns zero. Has anyone got any advice? Thanks


How to prioritize a current path in a circuit

Here's my problem:  I have a power supply rated at 5V, 2.1A  I need this to feed two devices, both running at 5V    Device one is a single-board computer that can consume anything between 0.5A and 1.5A depending on what it's doing. Device two is a battery charger, which is happy to take anything it can get up to (and quite possibly beyond) 2A, and equally happy to take no power at all.   I need a way to feed device one with as much current as it is demanding right now, and give whatever is left to device two.  In order to stay within the PSU limits, I'm going to be limiting the input current to 2A.  I'm a beginner, and from my limited understanding (so please correct me if I'm wrong) the chances are that device one could end up current-starved otherwise.  I'm not happy with simply making two fixed current-limited paths (1.5A to A, 0.5A to B) - I really do want any excess current delivered to device B, if there is any available for it.  The only thing I can think of is to dynamically monitor the amount of current currently going to devices A and B, and to throttle down device B by opening and closing current-limited gates with transistors (or using a variable current-limiting circuit controlled by a digital pot) with a microcontroller until the sum of the two is less than (2A minus a safety buffer), along with some caps in there to keep things running during switching.  However, that sounds a bit complex for something that I have a gut feeling ought to be much simpler, and possibly involves using some kind of specialized IC that I don't know the name of in order to search for it.  This is a problem I feel I'm going to run into with other things as well - not just charging a battery, so I'd like to know if there's any way (simpler than the complex microcontroller solution I imagined earlier) to manage the current distribution in a circuit when the supply doesn't meet the demand - some way to simply say "current goes here first, and what is left over goes there"


I dual booted ubuntu 12.04 LTS with Windows 8, but I wanted to get rid of ubuntu. So I got EasyBCD (on windows 8) and removed Ubuntu following a tutorial on youtube, then I got rid of the Ubuntu partitions. After restarting my Sony Vaio, it went to grub rescue and I'm not sure what to do. Help please! Much appreciated!!  I installed ubuntu using a USB.


I want to extract parameters values from a String that contains a method call. Example:  sort("KAMP_MR","BEZ ASC, lower(KAMPNR) ASC")   I need to extract the parameter values:  KAMP_MR BEZ ASC, lower(KAMPNR) ASC   I have a regex that works to some point  "[0-9a-zA-Z.,_()" "]*"   But this will match "KAMP_MR","BEZ ASC, lower(KAMPNR) ASC" but how do I split this by ,?


If $M$ is positive definite, then $\operatorname{det}{(M)}\leq \prod_i m_{ii}$

In the Wikipedia article on positive definite matrices they claim that if $M$ is positive definite, then the determinant of $M$ is bounded by the product of its diagonal entries. How might we show this?  Ideas: The sum of the diagonal entries of $M$ is the trace, which is also the sum of the eigenvalues. The product of the eigenvalues is the determinant. All the diagonal entries of $A$ must be real and strictly positive. Also we have $|m_{ij}|\leq \sqrt{m_{ii}m_{jj}}\leq \frac{m_{ii}+m_{jj}}{2}$. So far nothing is working...  We might try to write the Gram matrix $m_{ij} = \langle v_i, v_j \rangle$, and then $\prod_i m_{ii} = \prod_i \|v_i\|^2$. Now we'd need to show that the determinant, which is a polynomial in the entries of $v_i$, is less than $\prod_i \|v_i\|^2$ somehow.


i used mongoose ORM for mongodb operation. i want to store float value in filed.  here is my model  var mongoose = require('mongoose'); var Schema = mongoose.Schema; var Float = require('mongoose-float').loadType(mongoose, 8); var mongoosePaginate = require('mongoose-paginate');  var mymodel = new Schema({   amount : {type : Float},     note : {type :String,default : ''}, });   mymodel.plugin(mongoosePaginate); module.exports = mongoose.model('mymodel',mymodel);   the problem is amount filed is storing exponential value. for example i store 0.00000011 db stored 1.1e-7  how can store actual value in filed with datatype float?


How to change an Image in JFrame when a timer reaches a number?

as the title says, im trying to change an image in a jframe using a timer. but it throws a NullPointerException. I am pretty new at java, and while i am in the process of researching exception handling, any direction you can give me will help my learning greatly.  here is my code:  public class PointTest extends JPanel {     JLabel drawcloseLabel = new JLabel(new ImageIcon("src/images/draw_closeup.jpg"));     JLabel monsterAttack = new JLabel("src/images/monsterAttack.jpg");     JLabel endGameLabel = new JLabel(new ImageIcon("src/images/monsterAttack.jpg"));     private static final long serialVersionUID = 1L; // i dont get this     private JFrame frame;      boolean off = false;     public JButton opendraw;     // public JButton button2;     public JButton ok;     public JButton back;     public JButton pickUpKey;     public JButton Key;     public JButton unlockDoor;     public JButton lockedDoor;      public JButton btnNewButton;     JPanel background;     JPanel door;     JPanel draw;     JPanel drawopen;     JPanel endGame;      public void room() {          frame = new JFrame("room");           frame.setSize(1280, 960);         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);          JLayeredPane layeredPane = new JLayeredPane();         frame.getContentPane().add(layeredPane, BorderLayout.CENTER);          background = new JPanel();    endGame = new JPanel();     JLabel endGameLabel = new JLabel(new ImageIcon("src/images`/OutOfTime.jpg"));`     JLabel picLabel = new JLabel(new ImageIcon("src/images/room.jpg"));           background.add(picLabel);          endGame.add(endGameLabel);          background.setBounds(0, 0, 1280, 960);           layeredPane.add(background, JLayeredPane.DEFAULT_LAYER);       }   this is the method that, if i catch the exception, will continue the countdown to 0, but will not change the image.           public void EndTimer() {          //error         background.setVisible(false);          endGame.setVisible(true);         endGame.add(endGameLabel);         endGame.setBounds(0, 0, 1280, 960);         }  }   the countdown class for the Timer.   import java.util.Timer; import java.util.TimerTask;  public class Countdown {     static int interval;     static Timer timer;     boolean off;     PointTest pt = new PointTest();      public void Countdown1() {          int seconds = 10;         int delay = 1000;         int period = 1000;         timer = new Timer();          interval = seconds;          timer.scheduleAtFixedRate(new TimerTask() {              public void run() {                 System.out.println(setInterval());                 if (interval == 7) {                     System.out.println("works");                      pt.EndTimer();                  }              }         }, delay, period);     }      private int setInterval() {         if (interval == 1)             timer.cancel();         return --interval;      }      public int getInterval() {          return this.setInterval();     }  }    import java.io.IOException;    public class windowMain {       /**      * Launch the application.      *       */       public static void main(String[] args) throws IOException {           Countdown cd = new Countdown();         cd.Countdown1();         PointTest point = new PointTest();         point.room();         }  }   Stacktrace:  Exception in thread "Timer-0" works test java.lang.NullPointerException     at PointTest.EndTimer(PointTest.java:207)     at Countdown$1.run(Countdown.java:27)     at java.util.TimerThread.mainLoop(Unknown Source)     at java.util.TimerThread.run(Unknown Source)


Is windows built-in Remote Desktop secure? I mean, does it use any encryption methods? or someone can hijack the data that have been transferred between two system?


Say that we have the following:  template <class T, int i>   I understand that T will be whatever type being passed to some function. But, what does the int i portion mean?  Thanks.


Find the number of binomial coefficients in the expansion of $(1+x)^{2018}$ that are divisible by $13$   On searching the internet for a long time I found that these type of questions are relevantly solved using either Kummer 's theorem or the Luca's theorem. But I haven't studied them yet. So can someone please explain some method to solve these problem without using those theorems.


My phone has been infected with viruses for 6months now.  At first it was just a virus in disguise called "settings", but then it spread to my browsers opening many different sites. I had to disable my browsers. And now there are 3 other viruses on my phone. One called "clockwallpaper", second is the "lake worth isd". It creates a fake duplicate of an app that I'm using, and after I closed that duplicated app, the original app starts lagging and then crashes. It also activates the silent mode of my phone. The third one is called "system", which pop-up tons of ads that is really annoying. It also makes an app that I'm using to lag and stop working.  I tried to use Malware Bytes and Bitdefender antivirus softwares. At first it was good and they removed the viruses, and I thought the viruses will be gone permanently. But I was wrong, after an hour or less they get installed again, even I have an internet connection or not.  So I performed a factory reset on my phone to get rid of it.  And they were gone. But then later on they get installed again and my phone was now like before.  Please help me!


Currently having difficulty with Selection Sort and Bubble Sort codes. The selection sort is used to sort out student ID in ascending order and the bubble sort is used to sort out last names in ascending order. The program compiles but crashes upon choosing choice 10 or 11.   My array is declared as follows:   student[] list = new student[100]; //my array   This is the code that I have for selection sort and bubble sort. I am using an array with methods:     if (choice == 10) { // Dissplay the sorted array by student id              SortArrayBySelection(list);              System.out.println("Sorted studentid are:");             for (int i =0; i< studentNumber; i++)             {                 System.out.println(list[i]);             }            }          if (choice == 11){ // Display the sorted array by family name              BubbleSort(list);              System.out.println("The sorted names are:");             for(int i = 0; i < studentNumber; i++)             {                 System.out.println(list[i].Getfamilyname());             }         }       } while (choice != 1);    }  public static void SortArrayBySelection(student[] arrayToSort){ // Function to sort out the array on sutdentid  for(int i = 0; i < arrayToSort.length-1; ++i)  {      int minIndex = i;      int studentid3 = arrayToSort[i].Getstudentid();      int studentid2 = arrayToSort[minIndex].Getstudentid();      for(int j = i + 1; j <arrayToSort.length; ++j)      {          int studentid1 = arrayToSort[j].Getstudentid();          if(studentid1 < studentid2)          {              minIndex = j;          }      }      int temp = studentid3;      studentid3 = studentid2;      studentid2 = temp;    } }  public static void BubbleSort(student[] arraySort){     String t;     for(int i = 0; i<arraySort.length; i++){         for(int j=0; j<arraySort.length-1;j++){             String str1 = arraySort[j].Getfamilyname();             String str2 = arraySort[j+1].Getfamilyname();             if(str1.compareTo(str2)<0){                 t = str1;                 str1 = str2;                 str2 = t;             }         }     }  }   Any suggestions would be appreciated! thank you Errors:  Exception in thread "main" java.lang.NullPointerException     at client.Client.SortArrayBySelection(Client.java:270)     at client.Client.main(Client.java:232)  Exception in thread "main" java.lang.NullPointerException     at client.Client.BubbleSort(Client.java:288)     at client.Client.main(Client.java:246)


For equal cost, why would you select the MacBook Air over the MacBook Pro?

I can see that the 13" version of MacBook Pro and MacBook Air is same $1199, but the Pro is more feature-loaded than Macbook Air. Why would anyone buy MacBook Air? What's the catch in this?    I was thinking of buying a MacBook for development purposes, and worried if there's any problem in the Pro version, because it comes with more features (like more storage).  Edit:    Thanks for the answer guys, I bought a MacBook Pro a week ago and already loving it.


Updating ESTA details for second visit to USA

My ESTA is valid until Jan 2016. I am holding an Australian passport valid until 2017. I already made one trip to USA in May 2014. I will travel from Australia to USA in Sep 2015.    I have updated the new address where I will stay during the second visit on the web site of US Custom Border Protection. However I am still concerned about the flight details (airlines, flight number etc...) which I could not update.    Why not, or how do I, or need I not?


How to install a dictionary (danish) in Texmaker

I began my physics studies last summer. All our written assignment is in LaTeX and that's ok - and I use Texmaker. I think Texmanker is a good program and I have just one problem with it. I can't install a danish spellcheck and use it in LaTeX. That is not nice, so I really need your help!  Help me please. Tell me where and how to install a danish spellcheck and how to use it in Texmaker, pls. I am desperate! :/


Use bluetooth keyboard to access/edit BIOS?

Can I use a bluetooth keyboard to enter BIOS and edit the values there? I'm thinking of two scenarios:   A new machine - no OS (yet). So to me seems no possibility to pair the keyboard. Hence no access to BIOS? I have booted to an OS (Windows/Mac) once and paired the keyboard with the computer. Will the keyboard work before OS drivers are loaded?


The program should return how many positive and negative numbers there are in a sequence.  The main method will read a sequence of numbers from input and for each of them evaluate if it is positive or negative using this method below.       public static int positiveOrNegativeNumber(int n) {     int positiveNumber; //counter for positive numbers     int negativeNumber; //counter for negative numbers      positiveNumber=0;     negativeNumber=0;      if (n>0) {         positiveNumber = positiveNumber + 1;     } else if (n<0) {         negativeNumber = negativeNumber + 1;     }     return positiveNumber & negativeNumber; }   does the expression return positiveNumber & negativeNumber return them both?  edit: So, following Java Geo suggestion I got this:      public static NumCounter positiveOrNegativeNumber(int n, NumCounter numCounter) {  if (n>0) {     numCounter.setPositiveNumCounter(numCounter.getPositiveNumCounter()+1); } else if (n<0) {     numCounter.setNegativeNumCounter(numCounter.getNegativeNumCounter()+1); } return numCounter;   }  But I don't know what I should add in the main method to print it out      public static void main(String[] args) {     int n;      while(!Lettore.in.eoln()) { //while the line has not ended         n = Lettore.in.leggiInt(); //read n from input         // what is missing here??         }     }   Don't worry about Lettore.in.eoln and Lettore.in.leggiInt, are just methods that make getting things from input easier without having to use the scanner.


Can [sic] be used to show an omission or error in punctuation?  Eg:   Original:  He was, happy to get a raise.  Revised:  He was [sic] happy to get a raise.  There shouldn't be a comma after 'was'.  Original:  Mike liked lasagna, Diane preferred ziti.  Revised:  Mike liked lasagna [sic] Diane preferred ziti.  There should be a semicolon - not a comma - between the sentences.


In my code i am getting the output 20 24 48 but I think the output should be:- 19 19 43

Why output is incorrect?  I think the output should be:-  19 for the struct inside the union  19 again the same because Union reserves memory for the largest variable.  43 and the outside Struct is 43 because 19+20+4=43  #include<stdio.h> //structure //====================================================== struct {     char a[20];     int b;     union {         double c;         struct {             char d[15];             float e;                }x;           }y;        }z; //main function //====================================================== int main() { printf("%u\n%u\n%u\n",sizeof(z.y.x),sizeof(z.y),sizeof(z)); return 0; }  //Output is 20 24 48 //Assumed 19 19 43


Texture also applying to separated object

I am working on creating a hammer in Blender, but I am having a problem. I separated the hammer and the handle into two separate objects, but when I apply textures to one of the items, it applies the texture to both objects. I used P and then selection to separate the two pieces.


Can a necromancer True Polymorph to get an arbitrary CR 9-or-less companion?

According to  after a necromancer polymorphs an undead they control, it is still under their control. Assuming yes, I raise you an even more overpowered combo than a bunch of pixies running around:    A necromancer gets a permanent zombie via Finger of Death. The zombie gets polymorphed into an object via True Polymorph. After taking a long rest, the necromancer uses True Polymorph again, this time going for the "Object into Creature" option, turning their permanent zombie into any creature with a CR of 9 or less.   Is this possible RAW?


What is the best way to allow a user to select one value from a list of potentially hundreds?

I'm trying to write an Android app that requires users to select a value from a list of potentially hundreds. They're likely to know the item they're selecting to asking them to filter by typing seems like a sensible approach.  I've searched high and low but I can't find a standard way of doing this.  A spinner is no good and it takes too long to go through the list of values  An autocomplete box is no good as I need users to be contrained to only selecting items from my list.


To access chatter rest api using APEX code, I need salesforce instance server url in following format:  https://na17.salesforce.com  Is there any method which works in all cases  Case 1: Any Development Org  Case 2: My Domain Enabled  Case 3: Sandbox  Case 4: Managed Package


How do I properly change my password in Xubuntu 16.04 without breaking my system?

Yesterday I changed my Xubuntu 16.04 user password using passwd in the terminal. I continued working all day, everything was fine.  Today I turn on my machine, try to log in and I'm stuck in a log-in-loop. Every time I log in, the screen goes black, then it puts me back to the log in screen. It turns out that my ecryptfs password hadn't been updated, so I had to manually 'rewrap' it. 15 minutes wasted...  Then, I opened Chromium, and it asked for my keyring password. I entered my new password, and it wasn't accepted. I entered my old one, and it accepted that. Unfortunately because of this it seemed to have deleted all of my cookies, so every single website had been signed out. As somebody who uses Chromium all day every day, this was a big problem. 30 minutes wasted...  I then tried to change my password with the 'Users and Groups` GUI app, and upon clicking 'Change password', it hung like Windows Explorer often does... 15 minutes wasted.  So the question is - how do I change my password without causing these problems? As far as I know I didn't do anything out of the ordinary like manually editing /etc/shadow, so what went wrong?


Do smaller apertures provide more depth of field past the diffraction limit, even if peak sharpness suffers?

In Understanding Exposure (3rd edition, ), Bryan Peterson has what might be called a rant against modern on-line conventional wisdom about diffraction limits. Answers on this web site are pretty much in line with that conventional wisdom; see  and   But Peterson is particularly dismissive of "photography forum Web sites", and says he "wants to set the record straight". Is there a grain of truth to what he says, or is he totally off-base?  Particularly, he says that f/22 is "the smallest lens opening that, in turn, produces the greatest depth of field" with a wide-angle lens, and that f/22 is therefore the only way to record sharpness from front to back. Will stopping down beyond the diffraction limit give more consistent across-the-field sharpness, even if it isn't absolutely as sharp, perhaps? Or does the diffraction limit mean that at certain point, far before f/22 on APS-C dSLRs, everything is as as sharp as it's going to get, and beyond that, everything gets worse?  Peterson also says "The question of using f/22 was never an issue during the days when we all shot film, and it should not be an issue today." In , jrista (convincingly, I thought) argues that the limit is a function of the recording medium. Does Peterson, despite credentials as being a best-selling photography author, not give enough credence to the difference between film and digital?


In IPv4 Subnets - a /23 - How do we know which range to use?

Let's assume I don't know what my IP range is, or my default gateway, but I know my IP address is 192.168.5.38 and my CIDR Range is /23.  How do I know what my IP range is?  Is my range  192.168.4.0-192.168.5.255   or   192.168.5.0-192.168.6.255   Can we only work out this if we know the default gateway?  Please note I'm not asking what tools can provide this information, this is a thought exercise. I'm trying to understand how you would know the range when faced with a situation like this.  Thanks!  Answer:  thanks to @g_bor down below - they helped me understand how you work out the range. You do it by ANDing the binary outputs of both IP address and Subnet mask.   IP address: 192.168.5.38  Binary  11000000.10101000.00000101.00100110   Subnet Mask: /23 (255.255.254.0)  Binary:  11000000.10101000.00000100.00000000   If we AND them together (1 AND 1 = 1, 0 AND 0 = 0, 1 AND 0 = 0) we get  11000000.10101000.00000100.00000000   which is IP Range:  192.168.4.0


I have problems with complex mesh on CAD models, I found out that mesh chace displays different mesh in object mode, how can I apply it so I could see it in edit mode also?   Green picture is what I wont.  I dont wont to make animations, just simplefied object with texture ready for export but complex suface mesh gives me headache with UV maps and everything... Any ideas?


I am hoping to spend 6 months in Europe. I'm a Canadian citizen.   I'm aware of the 90 day Schengen visa and planning on applying for a D level visa for Italy to spend 90 days there.   My understanding is that this will mean I can spend 90 days in Schengen then enter Italy to activate this 90 day visa, would this be correct?  If yes, do those 90 days spent in Italy count as time not spent in Schengen therefore allowing me to go back to Spain, France etc or do I need to be out 90 days after my visa expires?  What if I do 60 days in Schengen, 30 days out, enter Italy and spend 90 days there, do I still have 30 days left to spend in Schengen?  Thanks!


Should my flair be including sites with less than 200 reputation?

I took a look at my profile, where I stuck my flair. Here's the flair:    However, I don't have 28k rep. According to chat, I have 19.7k.  Note: I know about the combined flair - I've had this in my profile for at least a year. It had been showing me the same as in chat, now it isn't.   What is going on here?  Edit: I'm reporting a bug here, that the combined flair is not showing the correct number, as it has in the past.


Package denyhosts in Ubuntu Trusty Tahr is deleted: temporary or forever?

While doing a test-upgrade of our Ubuntu server to 14.04, I found that the package DenyHosts is no longer available. Installing it gives following error:  apt-get install denyhosts Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package denyhosts   Apparently it has been deleted, according to .  Will Denyhosts be available in the final release of Ubuntu 14.04?


I have a strange problem. This is my code:   function bd7_services_services_resources() {   return array(       'get' => array(         'index' => array(           'help' => 'Ritorna le immagini inserite.',           'callback' => 'bd7_services_get_immagini',           'access callback' => 'user_access',           'access arguments' => array('access content'),           'access arguments append' => FALSE,         ),            'actions' => array (             'immagini' =>               array(                 'help' => 'Ritorna le immagini inserite.',                 'callback' => 'bd7_services_get_immagini',                 'access callback' => 'user_access',                 'access arguments' => array('access content'),                 'access arguments append' => FALSE,               ),           ),           'operations' => array(               // Define the index callback for a GET to /cart.             'immagini2' =>               array(                 'help' => 'Ritorna le immagini inserite.',                 'callback' => 'bd7_services_get_immagini',                 'access callback' => 'user_access',                 'access arguments' => array('access content'),                 'access arguments append' => FALSE,               ),           ),         )     ); }   If I call "rest/get" all works.  If I call "rest/get/immagini" I receive "404 Not found : Could not find the controller."  If I call "rest/get/immagini2" I receive "404 Not found : Could not find the controller."  Where is my error ?  "rest" is my "Path to endpoint".  Thanks.


import java.util.Random; public class RandomHomework {     public static void main(String[] args)     {         int i;         Random generator = new Random();         double randomDecimals = generator.nextDouble()-.04;         int randomNumber = generator.nextInt(9)+10;         for(i = 0; i > 100; i++)         {             if(randomNumber >= 10.00)             {                 System.out.println(randomNumber + randomDecimals);             }         }     } }   I am having a problem with the setup of my for loop and cannot figure it out... It runs perfectly fine when I remove the for loop.  As you can see I tried declaring the i previously but it made no difference.


Everywhere Super Dense Subset of $\mathbb{R}$

First, this question is motivated by the imprecise question: Is there a sensible notion of parity (evenness and oddness) for real numbers?   Here are some properties a notion of parity for $\mathbb{R}$ should have:    It should be an equivalence relation on $\mathbb{R}$ with exactly two equivalence classes.  Each equivalence class should be dense in $\mathbb{R}$. There should be some kind of symmetry between the two equivalence classes. (This is intentionally imprecise.)   If we divide $\mathbb{R}$ into rationals and irrationals, this lacks symmetry, since the rationals have measure zero and are countable, while the rationals have infinite measure and are uncountable.   So we could require that each equivalence class be uncountable and/or have positive (or infinite) measure. Then take one equivalence class to be the rationals, union with countably many fat cantor sets with positive measure, and the other class its complement. Then both classes are now dense, uncountable, and have infinite measure. But again, symmetry is lacking. One of these classes is "uncountable everywhere" and has "positive measure everywhere" while the other does not.   I propose some definitions: A subset $A \subset \mathbb{R}$ is uncountable everywhere if for any open interval $(a,b)$, the intersection $A \cap (a,b)$ is uncountable. A subset $A \subset \mathbb{R}$ has positive measure everywhere if for every open interval $(a,b)$, the intersection $A \cap (a,b)$ has positive measure. We can see immediately that having positive measure everywhere implies being uncountable everywhere, since a positive measure set must be uncountable.   Finally, my questions:    Is there a partition of $\mathbb{R}$ into two sets that are both uncountable everywhere?  Is there a partition of $\mathbb{R}$ into two sets that both have positive measure everywhere?  Is there a partition of $\mathbb{R}$ into two sets that split each interval $(a,b)$ into two parts of equal measure?   Potential generalizations for extra credit: What about partitions of $\mathbb{R}$ with $n$ equivalence classes, where $n \in \mathbb{N}$, or even with countably many, or even uncountably many equivalence classes?  Note: If you've seen these definitions of uncountable everywhere or positive measure everywhere somewhere under a different name, please let me know. I've never found anything where other people were thinking about these notions.  EDIT: By "measure," I mean Lebesgue outer measure, so we don't have to worry about anything being measurable.


How to set the language for API Rest or SOAP?

I'm integrating SF with other systems using the standard SF API (SOAP and REST). For this, I'm using a specific user which has a special profile (using API Only permission). The Integration user has the Language set on English.   However I need to return the request results on different languages (ES, FR, etc). For instance, the value of picklist should be translated.   Query  Is it possible set on login or in the request the language?


Is there such a thing as a full-text indexing engine, that can be queried from the command line and ideally wouldn't require using a gui at all ?  I'm especially interested in indexing my ebooks and papers, so that's a mixture of pdf, epub and a few djvu. (Open)Office docs would be nice, but much lower on my list.


Is there going to be a process around hellbanning?

Given , I must say I think the idea (making that user's content visible to only them) is a good one.  However, the people in whose hands that power will be placed terrify me.  Jeff is saying that he doesn't like that bans can degenerate into meta-discussions about the fairness of banning, and in that respect I agree with him. But the meta-discussions do accomplish one thing -- they get more than one person to look at the ban and weigh in on what they think.  This isn't that I don't trust moderators (or, indeed, diamond moderators), but I don't trust any one single human being with an irrevocable and complete banhammer, where there's no potential to dispute things. (And if the user doesn't know they're banned, there's no potential for dispute)  Basically, I'd sleep a lot more soundly at night knowing that if one of these "enhanced bans" are put into place, that at least two people have looked at the "problem child", and only after more than one person has signed off on such a ban, does that go into effect. I don't care exactly what that process is, but I don't want to have to worry about pissing off a moderator and getting banned as a result.  We all get pissed off here -- it's part of any community. But "the nuclear option(s)" need(s) to be decided upon by someone with a cool head, not someone who's pissed off.


Fix "Package system is broken" error without synaptic

The package system is broken  If you are using third party repositories then disable them, since they are a common source of problems. Now run the following command in a terminal: apt-get install -f  The following packages have unmet dependencies.  libegl1-mesa : Depends: libgl1-mesa-dri (= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed  libgbm1 : Depends: libgl1-mesa-dri (= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed  libgl1-mesa-dri : Breaks: libgl1-mesa-dri:i386 (!= 10.4~git1411171930.920f87~gd~t) but 10.5~git1411191810.9460cd~gd~t is installed  libgl1-mesa-dri:i386 : Breaks: libgl1-mesa-dri (!= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed  libgl1-mesa-glx : Depends: libgl1-mesa-dri (= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. E: Unable to correct dependencies   I'm on Ubuntu 14.04. I was using the update drivers from , so the first thing I did was remove that PPA, but this doesn't seem to have helped.  EDIT: I've followed these instructions, but to no avail:      Running these commands achieves nothing:  sudo apt-get clean sudo apt-get -f install sudo apt-get update   I don't have synaptic installed and when I try to install it, or remove packages using sudo apt-get remove --dry-run I just get more errors about unmet dependencies. I've been using Ubuntu for years and have always been able to resolve problems like this in the past, but something is eluding me here.


How to check Mime Type (Content Type) of a file?

I want to restrict a file upload based on extension type and mime type. However i found the fileextension field will always be null in before or after insert contentversion trigger and filtype field on content will have some different form of string. Ex- For excl filetype is "EXCEL_X" and file extension is null in after insert trigger. I want to get the mime type like 'applicaton/xlxs' or somewhat like that.


What will happen if someone create a fake account and use it to increase the reputation of his original account by up voting the questions and answers? Is there any mechanism available to find out these kind of accounts?


Recommendation: Advanced topics in quantum field theory

I have read Srednicki's Quantum Field Theory book. I want to learn more about advanced topics in field theory, such as geometry and topology in field theory, topology defect, anomaly, soliton, instanton, renormalization，advanced application in condensed matter physics and so on. Does anyone have anything recommended? Thanks


Wordpress Website not indexing in google, no error on google webmaster

I just recognized my SEO Score is 0 and that my wordpress website is not indexed on google search engine, no automatic filling as well. I am not an expert, I never used a sitemap, nor htaccess but it still worked always! After checking through analysis I found out that there is no title tag, no description, no meta keywords and headings, text html ratio is 0% , lots of syntax errors....idk what happened as I didnt change the website's structure, I just added something as its normal to keep the page updated... Google webmaster shows I have to index my page! I dont understand why, I never used blackhat SEO or anything fraud  my robots txt shows this  User-agent: *  Disallow: /wp-admin/  Allow: /wp-admin/admin-ajax.php  I know there are plenty of problems, but can someone tell me how i can easily make the page visible again as I dont know much about this? it always worked...maybe show me how a sitemap should look like and to prevent search bots to index wp admin, and if htaccess is important and how It should look like..is robots txt ok ? Thank you very much,  I am getting frustrated as I think I lost everything even if this problem is fresh (max 2 months)


Can Stack Overflow be cloned for internal use?

ISTM that a Stack Overflow-based setup would work great in many work environments. There are questions that can be answered internally, but you don't know who it is that may have the answer. Questions specific to a certain company or department, that wouldn't fit on Stack Overflow, or in cases where it's hard to be specific about your code when asking questions on Stack Overflow because thereby you might divulge too much of your company's secrets and possibly future directions/projects, etc.  I guess what I'm really asking is if there is such a thing as a "Stack Overflow in a box" or an Open Source Stack Overflow-esque framework that can be deployed for an internal work group? If not, what is the closest thing to it?


Why does the moon appear white/grayish and the sun yellow?

The Sun, as we all know, is white. Because our atmosphere scatters light the sun appears yellow to us hear on earth. So, why isn't the moon also yellow. Doesn't our atmosphere scatter its light. How about those little stars in the night sky, they don't look yellow.  I have heard the explanation that "the moon is dim and mostly stimulates the rods in our eye and not cones" but that's impossible! The moon does look orange/yellow when its low in the sky due to our atmosphere. So, why isn't it bright yellow when its up above our head like the sun? Same thing with the stars. Whats going on with the light?


How do I run the integrated video adaptor alongside the GPU on an intel?

I've got an Asus P8Z77 motherboard with a core i7 3770 processor, and a Geforce 660 video card. I'm running Windows 8.   While I primarily use the latter, there's situations where I want to use the HD4000 video adaptor built into the core processor - for example where I want to take advantage of quicksync. How would I do this?


Incorrectly scheduled events remain in sidebar after being cancelled

For the second time recently, I've managed to schedule a chat event for the wrong time (the date defaults to tomorrow?!). Once I realised this, I unscheduled the event. However, there is still a link in the sidebar on the main site, several hours after I did so:


Can Pokemon change gender when they evolve?

My female Charmeleon evolved into a male Charizard. How is this possible? Charmeleon was from Diamond transferred to Pokemon X.


What does it mean when a file is blocked in Windows?

When some files are downloaded from the internet, they are blocked. Some files can still be opened even if they are blocked...  I can see whether a file is blocked by opening the file properties (right-click > properties) and looking at General tab > Security (right under the Attributes section).  See for reference:    What does it mean when a file is blocked? How does a file behave differently in a blocked state versus an unblocked state?


Use mathematical induction to prove that 6(n+2) + 7(2n+1) is divisible by 43 for n >= 1.  So start with n = 1:  6(1+2) + 7(2(1)+1) = 63 + 73 = 559 -> 559/43 = 13. So n=1 is divisible  Let P(k): 6(k+2)+7(2k+1) , where k>=1  Show that P(k+1): 6((k+1)+2) + 7(2(k+1)+1) is true  = 6(k+1+2) + 7(2k+2+1)  = 6(k+3) + 7(2k+3)  I'm unsure where to go from here, I've tried several directions after this but have got nowhere. I don't know how to get the 43 or 559 out the front.  Any help would be great


How do tax brackets work? Do they yield significantly different results than a continuous curve?

In Canada (and many other countries), high-earners pay a greater percentage of their income in taxes than low-earners. Here is our Schedule 1 form:    The marginal utility of money decreases smoothly with increased income: If I earn $91,830, an additional dollar would be slightly less useful to me than the last one. The same is true if I earn $91,831 and earn an extra dollar, but the difference between the two cases is minuscule.  However, my marginal tax rate jumps up by 5.5%, which is not minuscule. Why is that? It seems there is nothing special about the value 91,831. Couldn't the marginal tax rate increase smoothly with income? Here is a made up example where the marginal tax rate increases linearly from 13% at $0 to 33% at $200,000 and then stays constant. The actual function used could be different, but the point is that it would reflect the "smooth" nature of the decrease in the utility of money. The blue line represents the actual function used in Canada.    Are brackets are easier to use than a smooth curve? Is it just a "good enough" approximation to make the calculation simpler? The Schedule 1 form would probably look something like this, which is not that bad: you could do this with a 4-function calculator.


Show that when $BA = I$, the solution of $Ax=b$ is unique

I'm just getting back into having to do linear algebra and I am having some trouble with some elementary questions, any help is much appreciated.  Suppose that $A = [a_{ij}]$ is an $m\times n$ matrix and $B = [b_{ij}]$ and is an $n\times m$ matrix and $BA = I$ the identity matrix that is $n \times n$.  Show that if for some $b \in \Bbb{R}^m$ the equation $Ax = b$ has a solution, then the solution is unique.


Get next character code adding 1 in Python

I have a variable which holds a letter. In order to have a concrete example let's assume it is 'A'.  I have a while loop which on certain conditions will change that variable to the next letter ('B' in this case).  I would like to know how to achieve that in python:  Pseudocode: char = 'A' next_char = 'A' + 1   Python: letter = 'A' next_letter = 'A' + 1 # This fails with error TypeError: can only concatenate str (not "int") to str


I downloaded Ubuntu 15.10 desktop software from its official website which was in a winrar file. I have been having problems to convert to a iso disc image file. Is there a link where i can download the iso file directly.


How many times is the print statement executed?

Hello,      I've gotten far on this exercise, with the following insight:   Here is a matrix of examples (vertical-axis is n=1,2,3,4,5,6,7,8; horizontal-axis is k=1,2,3,4)  1: 1  1   1   1     2: 2  3   4   5     3: 3  6  10  15     4: 4 10  20  35     5: 5 15  35  70     6: 6 21  56 126     7: 7 28  84 210     8: 8 36 120 330   Now, there is an obvious pattern among the numbers, being triangular numbers, sum of triangular numbers, sum of sum of triangular numbers, and so on. My question is:  Can you help me find closed form expressions for the sums of the entries:   Down the columns Across the rows And for general n,k?   Thanks!


Forced Oscillations: What exactly is happening?

In a forced oscillation, what exactly is happening? My textbook says that: The oscillator, initially, oscillates with the natural frequency. When we apply external periodic force, the oscillation with natural frequency die out; body oscillates with the frequency of the periodic force. Also, why is the amplitude maximum when the frequency of the external force is equal to natural frequency? I can understand it mathematically.  $$ A = \frac{F_0}{\sqrt{m^2(ω_d - ω)^2 + (ω_db)^2 }}$$                        where, $ω_d$ is the frequency fo the driving force  So when,  $$ω_d = ω $$ $$A = \frac{F_0}{(ω_db)}$$  But can you explain what exactly is happening when the frequency of, say the swing, is the same as the frequency of the force with which my friend is pushing me? This is confusing.


How is a qubit in superposition between $|0\rangle$ and $|1\rangle$ different from a mixture of $|0\rangle$ and $|1\rangle$?

Given that a qubit in equal superposition of $|0\rangle$ and $|1\rangle$ is represented by following wave function \begin{equation} \Psi = \frac{1}{\sqrt 2}(|0\rangle + |1\rangle) \end{equation} and associated density matrix \begin{equation} \rho_1 = |\Psi\rangle \langle\Psi| = \frac{1}{2} \begin{pmatrix} 1 && 1 \\ 1 && 1 \end{pmatrix} \end{equation} Further a qubit in this state is considered to be in a pure state (even though its in a superposition) since the density matrix can be cleanly factored into a product. Fact $F$ : When measured this qubit will turn out to be 0 or 1 with 50% probability each. But there exists another density matrix consistent with the same fact $F$ as follows: \begin{equation} \rho_2 = \frac{1}{2} (|0\rangle \langle0|) + \frac{1}{2} (|1\rangle \langle1|)        = \frac{1}{2} \begin{pmatrix} 1 && 0 \\ 0 && 1 \end{pmatrix} \end{equation} and this matrix corresponds to a mixed state. Clearly $\rho_1 \neq \rho_2$ but they have same physical characteristics which is the fact $F$. My Question: What is a physical fact or property that can be used to distinguish $\rho_1$ from $\rho_2$?


How to change the default behaviour of the fullscreen/maximize button?

that deals with the different behaviour of the fullscreen button in the window bar. There, it is shown that by doing:  ⌥ + ⇧ + Click on green or outer right icon (plus icon)  I can maximize a window in both width and height to the current screen.  Now I am wondering if I can make this behaviour standard just by clicking the icon. For an extra bonus, I wonder if there is a keyboard shortcut to achieve the same thing.


Why do all directional derivatives in $0$ exist for $f(x)=\frac{x_1^2x_2}{x_1^2+x_2^2}$?

Let $f: \mathbb{R}^2 \to \mathbb{R}$ be defined by $f(x)=\begin{cases} \frac{x_1^2x_2}{x_1^2+x_2^2}, \quad x\neq 0 \\ 0 , \quad \quad \, \, \, \,  x=0\end {cases}$.  Show that all directional derivates in $0\in \mathbb{R}^2$ exist.  My attempt:  Let $a:=(0,0)$ and $v:=(x,y)$ with $x\neq y$, then:$$\partial _v f(0)=\lim\limits_{t\to 0}\frac{f(0+t(x,y))-f(0)}{t}=\lim\limits_{t\to 0}\frac{f(xt,yt)}{t}=\lim\limits_{t\to 0}\frac{\frac{(xt)^2(yt)}{(xt)^2+(yt)^2}}{t}=\lim\limits_{t\to 0}\frac{t^3x^2y}{t^3(x^2+y^2)}=\lim\limits_{t\to 0}\frac{x^2y}{x^2+y^2}=\frac{x^2y}{x^2+y^2}$$ But that is just valid iff $x\neq y$. Do I have to show $x=y$ seperately?


Position of a relative clause before/after a verb

I'm not sure about the sentence structure below:  All kinds of problems arise that smaller animals or plants do not have to cope with.  It looks like that works as a relative pronoun for all kinds of problems, but I couldn't find such usage in my dictionary or online. This sentence could be divided into  There are all kinds of problems. Smaller animals or plants do not have to cope with all kinds of problems.  But, I can't figure out where 'arise' fits. If you have any thoughts, please share them.


Describing a motion of gyroscope with gimbal

Can you tell be how to set the equations to describe the motion of this machine in movie "Contact":     This is  with , am I right?


What is the result of $\bigcap_{n=1}^{\infty}{(-1/n; 1/n)}$

I would like to know the intersection of $(-1/n ; 1/n), \forall n \in N$. I am in trouble thinking it could be $\{0\}$ or $\emptyset$. Can anyone help me?


Copying text from OneNote and pasting creates an image instead of text

Steps to reproduce:   Write something in  Copy that text Try pasting in Stack Overflow It opens the image upload dialog box (Example: )   PS: I tried pasting the same in the  editor, and it pasted the text properly.  OS Version: Windows 10  I tested and replicated it on the following two browsers:   Chrome: Version 77.0.3865.90 (Official Build) (64-bit) Edge: Microsoft Edge 42.17134.1.0


I am a bit of a newbie with using pantones and the pantone color guide. I am currently working on a branding project where we will have print material in both pantone and cmyk, and also on screen rgb colors. I would like these colours to match as closely as possible. I used the Pantone color Manager program to help me find the cmyk and rgb references from my chosen pantone colors.  My problem is that there seems to be large discrepancies between the colors when going from the pantone to cmyk to rgb. , the grey pantone 431U is slightly blue which I like and of course want to preserve but when I use the cmyk reference it looks way more blue on screen when both of them are side by side.  I looked online for other convertors and I found other references that seem closer on screen then the one found in the Color Manager program. I am a bit confused and I would like to know the best way to achieve the right colors, as I won't be able to test print with the printer.  Thanks Fred


Why does not dark matter gather and form celestial bodies?

since the only thing we know about dark matter that it "attracts" and affect our Baryonic matter's momentum and speed, which means that it does have mass of a sort.  so why didn't we witness a darkmatter-darkmatter interactions in form of collisions of celestial bodies like stars, Black holes or other distinct things, what do we know about that?   PS: it would be very helpful for me if someone has an answer can cite it with a paper on the topic. thanks in advance!


Would a pipe from the surface to the Earth's exosphere suck all atmosphere to the space?

If I built a tube from Earth's surface to the exosphere, would all the air be sucked out to space?  If this pipe reached to a big planet, like Jupiter, would its gravity through the pipe suck our atmosphere?  If one end of the pipe was at the Earth's core, and other in the exosphere, would the magma go there, like in giant volcano?


I have a few questions on stackoverlow. 1 of them is unanswered so i searched for similar things to find a solution. During my google search i found . It is exactly my stackoverflow question (the original one, i edited it to be up do date). I was a bit shocked and searched for others of my questions and found  and . So i started looking for other SO questions on google to see if i am the only one on the Queforum. To some questions i could find a queforum link to some not. So my questions: Why are some SO questions on queforum.com? Thanks  EDIT: I have seen, that there is a , but it has got no answer and has been declared as possible duplicate of , but i don't hink it is. The question here is "Why are they on Queforum, all posted by the same user?" and the question there is "What can i do if i don'T want to have my question there?" so it is not really a duplicate.


With a UK 6-months visa, can I leave and re-enter before that?

I am Argentine, was travelling through Europe for three months and obtained a visa to come to UK for six months:    NWT 26164 Leave to enter for/until 6 months. No work or recourse to public funds. Immigration officer (6038) 13  sep. 2015   And he said I could not leave and apply for six more months soon. Three months have gone by and I want to go to Germany for one month.  Will I be able to come back into the UK?  My remaining time in UK will be the three months left of my visa?  So they gave me six months within how long, 12 months?


Show that $f$ is constant. Liouville Thm

Let $f$ : $\mathbb C \to \mathbb C$ be analytic such that $|Re(f(z)) Im(f(z))|$ $\le$ $1$ for every $z \in \mathbb C$. Show that $f$ is constant.   I know the set is bounded hence I should be able to apply Liouville Thm.   Other than this information I do not know how to approach this question.   Any help will be appreciated.


Find all polynomials $P(x)$ has $n$ rational roots.

Find all polynomials $P(x)=a_nx^n+a_{n-1}x^{n-1}+...+a_1x+a_0$ such as:  1) $(a_0,a_1,a_2,...,a_n)$ is a permutation of $(0,1,2,...,n)$  2) $P(x)$ has $n$ rational roots.


I am writing a scientific paper with my collaborator. We have submitted a version to a journal and now we got a review from them, so we need to fix a few things. In Microsoft Word there is the option to "track changes", which displays the deleted text as crossed out and the new text bolded (if I remember the details correctly). Is there a way to achieve a similar result in LaTeX?  I was thinking to create a new file for the revised version and then write a script which would basically compare the two files and make the differences either bold or crossed out before sending it to latex. Is there a tool that already does it?


How am I supposed to ask questions if I don't have enough reputation to comment?

I recently posted an "answer" to a self-asked and answered question with basically no votes. I was hoping to ask the poster a specific question about his code, but a moderator deleted it basically saying that it wasn't an answer and I should follow the rules.   This happened to me twice now, except the first time I wasn't deleted, just down-voted into oblivion. How am I supposed to ask questions and participate to earn reputation if I don't have any reputation to ask questions/participate within the guidelines? I came very close to 50 reputation points and then people went through and voted down my discussions with the OP.  This is almost akin to the "you can't get a job without experience" conundrum, and I feel an easy solution would be to lower the amount of reputation points required to comment on posts. It's ridiculous that this community is so hostile to someone who is only trying to contribute instead of just taking without giving back.  EDIT: Thanks, to whomever went through and voted up enough things to get me to 50 reputation points!


I am on Ubuntu 14.04. 64-bit and I am trying to install linuxband. To do I need to install the package libjack-dev, but when I do so I obtain the following message:  Some packages could not be installed. This may mean that you have requested an  impossible  situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  libjack-dev : Depends: libjack0 (= 1:0.121.3+20120418git75e3e20b-2.1ubuntu1) but it is  not going to be installed E: Unable to correct problems, you have held broken packages.   The point is that I do have the other libjack-jackd2 installed for example, but when I run the ./configure for linuxband I get:  checking for JACK_MIDI_NEEDS_NFRAMES... no   Which is the only no in the list. When I run the make, it generates a plethora of undefined references (examples:  src/main/c/linuxband-player.c: In function ‘main’: src/main/c/linuxband-player.c:768:2: warning: ‘g_thread_init’ is deprecated (declared at /usr/include/glib-2.0/glib/deprecated/gthread.h:261) [-Wdeprecated-declarations] g_thread_init(NULL); ^   or later  linuxband-player.c:(.text+0x50b): undefined reference to `jack_transport_query' linuxband-player.c:(.text+0x586): undefined reference to `jack_transport_query'  linuxband-player.c:(.text+0x5a1): undefined reference to `jack_last_frame_time' linuxband-player.c:(.text+0x615): undefined reference to `jack_last_frame_time' linuxband-player.c:(.text+0x672): undefined reference to `smf_peek_next_event' linuxband-player.c:(.text+0x6b5): undefined reference to `smf_event_is_metadata   and so on)   until it ends in:   /tmp/ccrh0o5V.o:remote_control.c:(.text+0xf01): more undefined references to `g_log' follow collect2: error: ld returned 1 exit status make: *** [target/linuxband-player] Error 1   Can someone help please?


Why doesn't smaller Transmission Lines affect Signal Integrity?

I am reading High Speed Digital Design: A Handbook of Black Magic. It was mentioned that if length of transmission line (Microstrip or stripline) is less than 1/10th of the wavelength of highest frequency component, then transmission line matching is not important. I am trying to visualize the phenomenon which will make matching insignificant for shorter transmission lines. I still think mismatch will cause reflection at the point of mismatch.   Can someone help me in understanding it? I am not sure if my question requires a detailed explanation and may be unsuited as a question over here. If this is the case, then please help me with finding relevant reading sources and some terms to google.


How long does it take to forge a Maester's chain?

How many links are needed to forge a chain? Are more links prestigious than others? How long does it typically take to earn a full chain?


Is there a word that contains all the vowels?

"Jealousy" contains most of the vowels but lacks 'i'. Is there a word in the English language that contains every vowel (and preferably 'y')?


how to find differential of $\sin^{-1}x$ using first principle?

I am trying to find out the differential of $\sin^{-1}x$ using fist principle as follows $$\frac{d}{dx}\left(\sin^{-1}x\right)=\lim_{h\to 0}\frac{\sin^{-1}(x+h)-\sin^{-1}(x)}{h}$$ I got stuck here what is next step to reach $\frac{1}{\sqrt{1-x^2}}$. could somebody help me ? thank you very much


Why would renormalization be necessary without divergent integrals?

Weinberg uses the LSZ reduction formula to introduce field renormalization,and on page 441, he says:     As this discussion should make clear: the renormalization of masses and fields has nothing to do with the presence of infinities, and would be necessary even in a theory in which all momentum space integrals were convergent.   I believe weinberg is right , but I can't convince other people: how is renormaliztion needed without infinities?  What does it have to do with the LSZ formula? I want answers to make clear the field renormalization with LSZ reduction formula. so maybe the question is different , because I am asking weinberg's book.


Can we keep a photon bouncing of mirrors for a long time (eg days)?

If a photon is sent into a box with perfect mirrors aligned in a way that it won’t ever be reflected out, is it possible to hold the photon for extended lengths of time with its quantum properties intact, and measure it when we want by opening a path into the detector?


How can I re-write the conditionals for this button

I've been trying out React for a couple of days and I tried to build a button component with some conditionals. Everything works but I feel like I am not doing it the right way. Could anyone review my code and give me some advice and tell me what I am doing wrong or what i could do better. I think I am using too many return statements. I use Typescript for type checking. Would appreciate any help! import { Link } from "gatsby";  interface Props {   content: string,   color: string,   path?: string,   type?: string }  export default function Button(props: Props): JSX.Element {   let elementType;    const checkProps = () => {     const availableColors = ['blue', 'grey', 'dark-grey', 'white'];     const borderColors = [''];     let buttonStyle;      // Check if props.color exists in availableColors     if(!availableColors.includes(props.color)) {       console.error(`"${props.color} color key not available for button style`);       return;     }          buttonStyle = buttonStyles[`button--${props.color}`];      // Check if props.content is valid     if(!props.content) {       console.error(`"${props.content} is not valid as content`);       return;     }      // Check if props.type exists     if(!props.type) {       elementType = <button className={ buttonStyle }>{ props.content }</button>       return;     }      if(props.type !== 'link') {       console.error(`"${props.type} is not a valid type, use 'link' instead or use nothing for default button`);       return;     } else {         elementType = <Link to={ props.path } className={ buttonStyle }>{ props.content }</Link>     }   }    checkProps();    return (     <React.Fragment>       { elementType }     </React.Fragment>   ); }```


Polynomials irreducible over $\mathbb{Q}$ but reducible over $\mathbb{F}_p$ for every prime $p$

Let $f(x) \in \mathbb{Z}[x]$. If we reduce the coefficents of $f(x)$ modulo $p$, where $p$ is prime, we get a polynomial $f^*(x) \in \mathbb{F}_p[x]$. Then if $f^*(x)$ is irreducible and has the same degree as $f(x)$, the polynomial $f(x)$ is irreducible.   This is one way to show that a polynomial in $\mathbb{Z}[x]$ is irreducible, but it does not always work. There are polynomials which are irreducible in $\mathbb{Z}[x]$ yet factor in $\mathbb{F}_p[x]$ for every prime $p$. The only examples I know are $x^4 + 1$ and $x^4 - 10x^2 + 1$.  I'd like to see more examples, in particular an infinite family of polynomials like this would be interesting. How does one go about finding them? Has anyone ever attempted classifying all polynomials in $\mathbb{Z}[x]$ with this property?


I meet my friend every day. I meet to my friend every day. I meet with my friend every day.   Is "meet" a transitive, or intransitive, or both?  I'd appreciate your help.


If your fighter casts Green-Flame Blade or Booming Blade, do you still get extra Attacks?

If you're a high-elf fighter who has the Extra Attack feature, when you cast  or , do you get to make your additional attacks?  If so, can you cast the spell again on those additional attacks?


How to get statistics of all samples through statistics of subsamples?

I know the statistics of several subgroups. For example,  Mean, variance, standard deviation, and number of group A Mean, variance, standard deviation, and number of group B  Group C = Group A + Group B With this information, can you find the mean, variance, standard deviation, and number of group C? Assuming that the values of each group are unknown


I've spent two days trying to install manually the cite.sty package in MiKTeX when nothing worked except putting it in the same directory as my .tex file. I run windows. I found the MiKTeX options (by searching "settings" in my computer), which display the following four root directories.   it says that sty file should be placed (respecting the structure tex/latex/cite) in the local texmf directory structure but  and  it says that it should be in the home texmf directory. Part of the problem is that I don't have any directory in my computer named "texmf" (or "localtexmf" or "texmf-local"). After putting the file in the right place one must refresh FNDB, which can be done on MiKTeX options or by typing "texhash" in the command prompt. When I did the latter I noticed that only the first three directories in the list were being searched. Now when you put the mouse over the different directories, on all of them except c:\mytexmf the following warning comes up.  This directory is maintained by MiKTeX. You should not install your own files here, because they might get lost when MiKTeX gets updated.  On the c:\mytexmf directory the message comes:  This directory can be used for local additions.  So I intended to put the file there, but, unlike with all the others, I cannot find this directory in my computer. I don't know if the fact that the "c:" in the address is lowercase means something. So I went back to trying to identify the home and local texmf directories. Following the advice in the last link I wrote the following commands in the command prompt.  -var-value=TEXMFHOME -var-value=TEXMFLOCAL  The first one yielded the error message "unrecognised option -val-value-TEXMFHOME" but the second one came back with "C:/Users/pablo/AppData/Roaming/MiKTeX/2.9". Piecing things together I guessed that the "C:\Users\pablo\AppData\Local\MiKTeX\2.9" directory was, despite the name, the TEXMFHOME directory. I included the correspoding directory tree and file (tex/latex/cite/cite.sty) there, refreshed FNDB with the command "texhash" and it worked. The problem though is that I'm still not sure whether this is the ideal place to put the file, and whether it might get lost when MiKTeX is updated. And the problem remains that I cannot find the c:\mytexmf directory. Extra information:  it states: "UserInstall: the installation destination for packages installed by the user", where "Userinstall" corresponds (see image above) to my TEXMF-LOCAL directory. This is a bit confusing considering the warning message, and the fact that it worked when I put my package in the other directory. I can't find the MiKTeX console and I'm not at all sure that I have it. I did find the package manager but when trying to use it to install the package it yields the following error message:  get host by name failed in tcp_connect()  The information  and  seems to contradict on whether MiKTeX includes by default a local texmf tree. In my case it seems that the answer is yes. Other useful links:


I just modified an answer and I can see that there are some missing highlights for the scheme language.  It's unclear what is not handled by the highlighter. But I'd say that the current functions are quite "standard" enough to get added to highlighting.   begin display newline set!


Testing convergence of series $\sum_{n=3}^\infty\frac{1}{n (\ln(n))^p(\ln\ln(n))^q}$

Lets have this problem. $$\sum_{n=3}^\infty\frac{1}{n (\ln(n))^p(\ln\ln(n))^q}$$ I have rewritten this to a form $$\sum\frac{1}{np'^{\ln\ln(n)}q'^{\ln\ln\ln(n)}}$$ For $p,q\in\mathbb{R}$. Obviously, $p',q'>0, p=\ln(p'),q=\ln(q')$


Marcus number fields exercise 30 chapter 3

This exercise wants me to prove that for each $m \in \mathbb{Z}$ there are infinitely many primes $p \equiv 1 \pmod{m}$. It seems that this can be based on the fact that $f$ has a root mod $p$ for infinitely many primes $p$ whenever $f$ is a nonconstant polynomial over $\mathbb{Z}$. This is from the exercise 30 on chapter 3 of Marcus' Number Fields. Please help me.


C# how to detect operators in string to calculate?

Say a program receives an input string "8*10+6/2" and should output 83, in this case. how to handle the operator?   I can chop the string into individual strings, then detect whether it is a number or operator. If it is an operator I can convert it to int. But I have no idea how to handle the operator so that the calculation works.


Underbrace with something else than a bracket

The $\underbrace{a=b=c}_{\text{comment}}$ command is producing a bracket below the equality $a=b=c$ and gives the opportunity to write a comment below that equality. Is it possible to replace that bracket by something else, such as an horizontal $[$?


Some Launcher icons disappear. I locked them but they have disappeared again after boot.  I have Ubuntu 12.04.2 LTS which I have installed today and updated.


I have a certain set of equations in my document which I would prefer cleverref to reference using a different noun. That is, for some equations I would like cleverref to reference those equations as usual, e.g., Equation 1. However, for a specific set of equations I would like cleverref to reference them as Rule 1.  MWE  \documentclass{article} \usepackage{amsmath} \usepackage{cleveref}  \begin{document}  \begin{equation}\tag{I-EQ}     \label{eq:1}     a + b \end{equation}  \begin{equation}     \label{eq:2}     c + d \end{equation}  Reference \Cref{eq:1}. Reference \Cref{eq:2}.  \end{document}   In the above example, I would like eq:1 to be referenced as 'Rule  (I-EQ)', while eq:2 continues to be referenced as 'Equation 1'.


Blender is rendering an older version my project

Blender is rendering an older version of my project, not the most recent one. I have made it using the Blender Render but it does not want to render in cycles either. A black and grey screen is rendered as if everything is transparent. Checked general camera, lighting and compute devises in case I messed something up but I can't find anything. All my textures and objects look normal, does anybody know what is wrong or what to check?  Ok added link:


Every group homomorphism from $(\mathbb{Q}, +)$ to $(\mathbb{Q}, \times)$ is the trivial map.

How do you show that every group homomorphism from $(\mathbb{Q}, +)$ to $(\mathbb{Q}, \times)$ is the trivial map? I am trying to use proof by contradiction by assuming there is an element $\frac{a}{b}$ such that some homomorphism $\phi$ has $\phi(\frac{a}{b}) = \frac{c}{d} \ne 1$. But I cannot seem to deduce any contradictions from here. Maybe using direct proof is a better approach? Any help is appreciated.


Find Familiar: familiar's movement when casting "touch" spells

Find Familiar PHB p.240:  (...) In combat, it rolls its own initiative and acts on its own turn. A familiar can't attack, but it can take other actions as normal. (...) (...) Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. (...)  I highlighted (what I interpret as) the prerequisites for casting spells through a familiar. Example My wizard has a familiar and the cantrip Shocking Grasp, which has a melee spell attack. In our first game, my DM ruled that on the familiar's turn my wizard could cast Shocking Grasp through the familiar, using its reaction. Allowing it to move in swiftly when needed and (possibly) deliver a "shocking bite". After reading  I realise that the casting of the spell needs to happen in the wizard's turn, not the familiar's. This makes me wonder whether the familiar could hold its reaction when the wizard casts the spell, so that on the familiar's turn it can move into melee before releasing the spell. Could "entering melee range with target X" be a trigger for a familiar's reaction? Or does the familiar already need to be in melee range before its spellcaster commands it to cast a melee spell?


the position of 'not' when using the To-infinitive

I have learned the position of 'not when I use to-infinitive is before the to-infinitive like:     I didn't go home not to meet my cousin.   but, sometimes I have seen 'not' is behind the to-infinitive like.     While patience is one of the most important parts of finishing a task, we sometimes cannot bring ourselves to not just expect quick results.   I am wondering if the expression,'to not just expect~', is right or wrong.  Please help me.


Does 'flight attendant' refer to men, woman or both?

In English there are some words which just refer to men, like Sir, or just refer to women, like Madam. Does flight attendant refer to women, men or both?


How many edits can a high-rep user have?

5 edits on own posts per day, more for high-rep users (scales with reputation)    does not say anything about the exact number a high-rep user can have. Can someone tell me how many edits can a high-rep user have(not just on his own posts)?


Problem 3: Central Limit      Consider tossing a fair coin $100n$ times, where n is geometrically distributed with mean 6. Due to a counting error, it is reported that the fraction of heads is in $[0.5,0.51]$. What is the most likely value for $n$?   We've been using the de Moivre Laplace approximation using a standardized sum.     $$ P\left(.50\times100n\leq \frac{S_n -\frac{1}{p}}{\frac{\sqrt{1-p}}{p}}\leq .51\times100n\right) = S_n \Phi(b) - \Phi(a) $$  and we start with $\frac{S_n}{n}$ and manipulate the bounds so we have $S_n^*$.  Which $\approx \Phi(285.34n) - \Phi(279.86n)$  I can't imagine this is correct. How does the Bernoulli trial enter the calculation?


I would like to debug an external launched jar application inside my Eclipse.  The way I'm launching the jar file is:  java -jar "D:\tools\swagger-codegen-cli.jar" generate -i http://guest1:8080/dbox/cmng/swagger.json -l typescript-angular2 -v   This jar file is generated using mvn package and copied in D:\tools\.  I've cloned git repository and I've imported the maven project inside Eclipse.  Is there any ideas?


Can I leave a process running on the computer I'm connecting to through ssh such that I can turn my own computer off?

I'm connected to a server through ssh and want to run a process that will take a long time. I connect to the server by using ssh in my laptops terminal, but I want to be able to turn my laptop off but still have the progress running on the server. Since they're two separate computers, it seems like I should be able to do this, but I'm not sure if it's possible through ssh.


why search results differ so much when the search term [what is a ...] is asked within quotes or not

A couple of months ago I had published on my blog an article with a title in the form: what is a table (table is not really the word I used-I write the word here as an example).  I had seen through Google Keyword Planner that this search term has very low competition and a decent volume. However, when I search in Google for this term I cannot find my post even in the last page after 450 results. Apart the first couple of Google pages with relevant results, all other pages which outrank my post do not answer the particular question (what is a table) but they have a great density of the word table in their content just because they happen to make or sell tables.  On the other hand, when I put the search term in quotes ("what is a table") I find my post in the 7th position of the first page!  My post's url is in the form www.example.com/eating/what-is-a-table/ and the post is optimized with Yoast SEO plugin (wordpress). The plugin returns that my keyword contains a stop-word which is the word "a", however I have to include "a" as it is a part of the search term which I'm targeting. My site is 15 months old but I rank decently in other search terms. For example in the term [table definition], my relevant post ranks on the 4th page. The posts [what is a table] and [table definition] were published on the same date.  In light of the above explanations and in a few words the question is: why search results differ so much when this search term what is a ...  is asked within quotes or not.


How to programmatically get amount of memory used by process?

I'm running some test codes (my own) and I'd like them to self-report how much memory they use. Ideally this would be a high-water mark. Something like what Activity Monitor or top report.  C++ code, and needs to work on OSX and/or Linux. An approach that works for both would be great, if not something that works on either one would be welcome.  How can an OSX program find out how much memory it's using?


unzipping a folder throws error: End-of-central-directory signature not found

$ unzip ABC.zip Archive:  ABC.zip   End-of-central-directory signature not found.  Either this file is not   a zipfile, or it constitutes one disk of a multi-part archive.  In the   latter case the central directory and zipfile comment will be found on   the last disk(s) of this archive. unzip:  cannot find zipfile directory in one of ABC.zip or         ABC.zip.zip.zip, and cannot find ABC.zip.zip.ZIP, period.   How to unzip ABC.zip folder? Folder contains sub-folders and tex files. My friends are able to unzip the same folder while my system throws the above error message.


If someone could give answers and explain, it would be greatly appreciated. Help required studying for a final.  One hundred tickets, numbered 1,2,3,…,100, are sold to 100 different people for a drawing. Four different prizes are awarded, including a grand prize (a trip to Tahiti).   A) How many ways are there to award the prizes?  B) How many ways are there to award the prizes if the person holding ticket 47 wins the grand prize?  C) How many ways are there to award the prizes if the person holding ticket 47 wins one of the prizes?  D) How many ways are there to award the prizes if the person holding ticket 47 does not win a prize?  E) How many ways are there to award the prizes if the people holding tickets 19 and 47 both win prizes?  F) How many ways are there to award the prizes if the people holding tickets 19, 47, 73, and 97 all win prizes?  G) How many ways are there to award the prizes if none of the people holding tickets 19, 47, 73, and 97 wins a prize?  H) How many ways are there to award the prizes if the grand prize winner is a person holding ticket 18, 47, 73, or 97?  I) How many ways are there to award the prizes if the people holding tickets 19 and 47 win prizes, but the people holding tickets 73 and 97 do not win prizes?


What happens when I grab a hanging rope mid-jump?

Suppose I'm flying through the air after a jump, and grab the end of a rope that's hanging straight down. At the moment I grab the rope, I have a certain velocity vector $v$ and am only under the influence of gravity. What kind of trajectory do I follow after grabbing the rope?  For instance, suppose the vertical component of $v$ is negative (downward). Does the rope just instantaneously zero out the vertical component of $v$, while leaving the horizontal component intact? If the vertical component of $v$ is positive, do I continue to move in a parabola, unaffected by the rope until it becomes taught?


Why did Robb Stark invade the south rather than hold the north?

From what I've been seeing and reading Robb Stark's plan does not make ANY sense.  What is the point of attacking the south rather than just holding the north? At the end of the day control of a land is only there if there are men to hold it. Why not just stay in Winterfell and rule the North as it's own kingdom? Perhaps build a wall or check point or two on the southern border to hold off southern invading forces.  This question is different from its supposed duplicate  because it is not about whether the rebellion should have happened. Independence is not official until it is recognized publicly unlike the contention in the duplicate.  This question is about his tactics to secure independence.


how to read body of a post packet in java

Basically I have created a java server which reads incoming packets, but the problem is when a post packet comes it doesn't read the body portion that contains the actual data, it shows the message as POST /index.html http/1.1.  Here is how i read the data on my server:  try{     IR = new InputStreamReader(socket.getInputStream()); }catch(Exception ie){     System.out.println("Cound'nt create IR"); }  BufferedReader BR = new BufferedReader(IR); String MESSAGE = null; try{     MESSAGE = BR.readLine(); }catch(Exception ie){     System.out.println("Cound'nt Receive Message"); } System.out.println(MESSAGE);   Could you please tell me how to read the body of the received packet?


Removing a row of a table on the fly - not working

In a view of a MVC app a table is presented to the user. This table doesn't have a head row, only the
 rows. Each row has a column with the name of a document and a button to delete it, as below:

             AD201	                              <button class="excluir" data-id="AD201" title="Delete the document">Delete</button>

             AD504	                              <button class="excluir" data-id="AD504" title="Delete the document">Delete</button>

   Well, to accomplish this I wrote the following jQuery function:  $('.excluir').click(function () {     $('#doc-' + $(this).data('id')).fadeOut(); });   It's not working. Why? I have a similar code to these in another view and it's working perfectly. What am I doing wrong? What am I missing?


I've rendered my final scene but the emitting light from the bulb shows a weird pixelated shade at the base and on the bulb... however it seems like its clear in the viewport render.  Any ideas? Is it the emission node?  View port light looks clearer...    Final render looks very pixelated...


UI issue on Stack Overflow profile page: HTML is not decoding properly for the badge on the mobile app

As seen in the badge earned section, amp; instead of which & should be shown on the Stack Overflow  profile page.   Android:  (Lollipop). Stack Overflow app, latest version.


We have all heard the buzzing sound that your speakers makes when you use your phone near your radio or amp. My question is why does one hear this interference if GSM operates at ~800-900MHz which is 40x higher than the highest humanly audible frequency?


Is there an alternative to iTunes where I can buy music/back up phone?


How do I see what symlinks exist for a given directory?

I want to do some housekeeping in a directory, and I want to see if a given directory has any symlinks pointing to it. I can easily enough see what directory a symlink points to, but now I want to see the relationship in reverse.


What is the difference between using a probability distribution and using the mean of observations only as a measure to describe the data?

I am wondering using the mean only without a specific probability distribution to predict or infer an appropriate measure for the average height of female students. I ask this question because I usually see a probability distribution with the mean and the variance as the parameters of an assumed probability distribution. So, I wonder that if I want to calculate and use the mean as an approximation of the mean height of female students,  Is it a must to assume a probability distribution? Can't I just use the mean as an approximation or a predicted value without assuming a specific probability distribution ? Can I still call using the mean only to approximate the mean height of femal students a statistical model? If I can't call it a stistical model, then what should I call the way I try to approximate the mean height?


Is there an easy way to list CLI tools installed on macOS?

So I have various command line tools like node, stats, etc which help me with day to day tasks, however I've noticed they don't show up in storage manager under applications and am unsure if there's a way to list all of those tools and completely remove all the files of the ones I don't use any more. It'll show as extra system memory use. It's not a big deal however I don't want to waste space. Is there a tool to manage all of this?


OLS / MLS estimation with sum of the beta = 1?

In my research I am using an OLS multiple linear regression like: $$ y_i = x_i^T\beta + \varepsilon_i $$    $y_i$ and $x_i$ are some 2-by-1 matrices (forecasts from 2 different models).  Now I want to perform OLS (which I am able to). The problem is that the elements of the $\beta$ can be negative and the sum is not necessarily $1$. Do you know any reference or algorithm to impose these restrictions?   $$\sum \beta = 1\text{  and  }\beta_j\ge 0\ \   \forall j$$


Why are magnetic fields a consequence of special relativity?

I'm very confused about why it is a consequence of special relativity.


Can "meet her" be pronounced [miːdər] in American English?

I heard people say meet her as  [miːdər] in an American movie.  Is it ok to pronounce it like that, or am I mishearing?


initializing an array from objects makes NullPointerException

I want to set some data in array from objects, here is class A, it cause an NullPointerException. Why? how to solve this? what is the problem with my initializing?  class A {      int a;      public void setA(int a) {         this.a = a;     }  public class ObjArry { public static void main(String[] args) {      A[] ObjectArray = new A[5];      ObjectArray[0].setA(10); //Exception occurs in this line     ObjectArray[1].setA(9);     ObjectArray[2].setA(8);     ObjectArray[3].setA(7);     ObjectArray[4].setA(6); }


How do I completely uninstall default Unity Greeter and use text mode login instead?

If I would like to completely uninstall the default Unity Greeter and use text mode login instead, how should I go about it?  I am using Ubuntu 14.04 LTS - the regular flavor; with Unity.  I prefer a command-line solution that can be scripted later.


How to write multiple lines of text in a box created using \framebox in LaTex

I want to draw block diagram of a system. I used \framebox command to create blocks. But when I write long text inside the box it comes out of the boundaries of block. How can I write text in multiple lines? I used following code for making block diagram  \begin{figure*}[h] \setlength{\unitlength}{0.14in} % selecting unit length \centering % used for centering Figure \begin{picture}(32,15) % picture environment with the size (dimensions) % 32 length units wide, and 15 units high. \put(3,4){\framebox(6,3){Symbol Mapping}} \put(13,4){\framebox(6,3){$N[\cdot]$}} \put(23,4){\framebox(6,3){$H_{C}(q)$}} \put(0,5.5){\vector(1,0){3}}\put(9,5.5){\vector(1,0){4}} \put(19,5.5){\vector(1,0){4}}\put(29,5.5){\vector(1,0){3}} \put(-1,6.5) {$u(k)$}\put(30,6.5) {$y(k)$} \put(9.5,6.5) {$x_{B}(k)$}\put(19.5,6.5) {$x_{C}(k)$} \end{picture} \caption{An LNL Block Oriented Model Structure} % title of the Figure \label{fig:lnlblock} % label to refer figure in text \end{figure*}


I am trying to create a bounding box for my sprite using box2d, but the box is being created at the wrong spot. I followed a tutorial on the wiki using this code      BodyDef bodyDef1 = new BodyDef();     bodyDef1.type = BodyDef.BodyType.DynamicBody;     bodyDef1.position.set(player.getX(), player.getY());     playerBody = world.createBody(bodyDef1);     PolygonShape square = new PolygonShape();     square.setAsBox(player.getWidth() / 2, player.getHeight() / 2);     FixtureDef fixtureDef1 = new FixtureDef();     fixtureDef1.shape = square;     fixtureDef1.density = 0.1f;   Player is a just the sprite that I am trying to create the box around.


Smallest possible triangle to contain a square

I was looking at * and started thinking about the case of a polygon with 4 sides: a square.   The question asks for a program that can take a polygon of N sides and return the smallest possible polygon of N-1 sides that contains the original polygon.  Thinking about it, I wasn't sure what the optimal triangle encapsulating a square would look like. In KSab's answers, he returns a triangle that looks like this:    This area is 2*(area of the square). With some easy guess-and-check work I found that this seems to be optimized. How do you prove that there is no better solution?  EDIT: another consideration for the orientation of the triangle could be this:


Is there a bug in the user reputation league table?

Today, while going through the , I found one user with  Total reputation : 3,494 Month reputation : 3,513.  TL;DR : This month rep point is more than total rep Screenshot:  My simple question: How (why) is this possible? Is it a bug?


Can a character meet prerequisites using a magic item?

Just as the title says, I'm wondering if a character can meet the prerequisites of a particular choice (feat, prestige class, etc.) by using a magic item that grants the prerequisite?  As an example: Xyitol is a Wizard 10/Rogue 1.  He wants to take a level of Arcane Trickster.  He meets most of the prerequisites, but he only does +1d6 sneak attack damage, when the class requires +2d6.  He takes a trip down to the local magic item shop and picks up a rogue's vest (MIC 130), which grants an extra +1d6 sneak attack damage.  Can Xylitol take a level of Arcane Trickster once he's wearing the vest?  I am aware of the line in Complete Warrior that says that you can lose access to a prestige class by "the loss of a magic item that granted an important ability".  This line is sort of an oblique reference; it describes what happens if you lose an item that grants a prereq, but it doesn't actually say that you can use benefits gained from magic items as prerequisites.  Is there anywhere that states positively that you can use magic items as prerequisites?  The difference between this question and  question is that I'm not looking for an answer on how to run magic item prerequisites in the game, I'm looking for rules citations that support or deny using magic items for prerequisites.


Have suggested edits also show the comments to a post

Some suggested edits like  at first look like another user trying to hijack a question. Until you see the suggestion's comment stating "Added code snippet provided by OP" - but anyone could claim that, so now you have to open the question in a new tab to check for . I therefore propose that comments are also viewable directly in the edit review view.


Export data as CSV in back end with proper HTTP headers

I wrote a plugin that displays all products in a woocommerce store in admin settings option, now I want to add a link to download the products as CSV file.  The problem is, when I click the link I get a permission error saying I don't have permission to view this page.  Here's my code:  function extra_tablenav($which) {     if ($which == "top") {         echo '
'         . __('These products are currently in the database:')         . '
' .         '&nbsp;&nbsp;&nbsp;' .         '' . __('Export to CSV') . '';     } }   How can I fix those permissions?


In Back to the Future Part II, why is old Biff in a lot of pain?

In Back to the Future Part II, there is a scene where old Biff exits the DeLorean. Here he seems to be in a lot of discomfort. He breaks his cane too. He just made himself a rich man, shouldn't he been seen coming back happy?


Lubuntu: Attach Wifi Driver to fix "network UNCLAIMED"

be warned: I'm a complete newbie to everything Linux, so please ELIF and I'll try to keep up :)  I'm trying to set up Lubuntu on a cheapo laptop that currently has Windows 10. I have my live USB and successfully booted Lubuntu, but while checking to ensure that everything works, I see that I can't connect to wifi. My wifi adapter (Realtek RTL8723DE 802.11b/g/n PCIe Adapter) doesn't appear on Lubuntu's Additional Drivers page, and when I run lshw -C network, this adapter is listed as "network UNCLAIMED" and doesn't list a driver. This is similar to the problem described by this user: .  So apparently this problem arises from a device with no drivers attached. The solution given in that thread seems to apply specifically to Ubuntu JauntyJackalope; so my questions are as follows:   How do I determine which driver/backport/etc to install based on my distro and my network adapter, and can I just install them with sudo apt-get install? (Ideally I'd like a general way to figure it out in case I want to, say, install Linux Mint instead.) Although I can access the Internet to install things with apt, it's a pain; is there a way to load the driver onto a flash drive and install it from there?   EDIT: As requested, some more terminal output:  $ lspci -nnk | grep 0280 -A3 03:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8723DE 802.11b/g/n PCIe Adapter [10ec:d723]     DeviceName: WLAN     Subsystem: Hewlett-Packard Company RTL8723DE 802.11b/g/n PCIe Adapter [10ec:d723]  $ uname -r 5.3.0-18-generic


What is the value of $g$ at the centre of the Earth? Is it zero or infinity? My attempt: I know it's zero but applying law made me on fused.


I read that stars show both absorption and emission lines. While how we see absorption lines is clear to me, I don't understand how (and when) we see the emission lines. Based on what I read in several of your threads such as  we should not be seeing emission lines at all, since all the emissions would come from the hotter interior but those can't reach the outside (unless I misunderstood this point), and the only emission we see is blackbody radiation. But then how do we see the few emission lines such as in the spectrum shown ?


Would you take a share in Stack Overflow?

Joel Spolsky has just posted  where he talks about seeking venture capital for Stack Overflow.  If instead they opted to seek shareholders from the StackOverflow community along the lines of the , but at a larger scale, would you be interested?  I'm asking this because I suspect there might be enough fanatics willing to invest $500 or so in a product they love to raise a considerable sum. People also often talk about the motivation for high rep users. It seems to me having an actual stake in the product might be a decent incentive (especially if you also get a gold badge for buying shares).


Prove that $(ab)^\mathrm{n-1}$ = $b^\mathrm{n-1}*a^\mathrm{n-1}$ where n > 1 is a fixed integer

For all $a,b$ in a group G, show $(ab)^\mathrm{n-1}$ = $b^\mathrm{n-1}*a^\mathrm{n-1}$  where n > 1  is a fixed integer. Given $(ab)^n = a^nb^n$  I took inverse on both sides and got $a^n b^n = b^n a^n$ but unable to proceed further.  My book solution has straightaway started with first step as $[b^\mathrm{-1}(ba)b]^\mathrm{n} = b^\mathrm{-1}(ba)^nb$   I don't get how this step is reached.   P.S. : My previous similar question has been marked as duplicate with  I am re-asking to clarify that $n$ in this question belongs to any integer whereas mine has a fixed value. Also, I am unable to derieve my own solution even after doing the steps mentioned in same.


Can we get click/open details from emails being deployed from Journey Builder?

We have set of journey emails which will be deploying based on subscriber activity. But we have to get complete journey subscriber activity details in one Data Extension. Is it possible to get it by using Query?


How do I find the supremum and infimum of this set

$$A=\left\{\dfrac{mn}{1+m+n} \mid m,n \in \mathbb N \right\}$$ I'm relatively new to this whole infimum and supremum proving. I've tried for a long time to prove the infimum of this set (which I believe to be 1/3). Can someone please help me and provide a proof for that?


Is the square of a prime necessarily larger than the next prime?

Let $p_n$ represent the $n$th prime number.  Is the following formula necessarily true?  $$p_n^2 > p_{n+1}$$  Experimentally, it seems true but I don't know enough number theory to prove it.  My problem is that I don't know enough number theory to relate primes to each other.  I know enough math to use the  to prove it for sufficiently large $n$ but I can't prove it in general.  My question is whether this relationship is true in general and, if so, what is a proof for this result?  Thank you...


My favorite food is apples. Or my favorite food are apples.


How to put a unique material on duplicated objects separately?

I've a sphere and then duplicated it. In object tree they are displayed as three siblings. I selected on of them and created a green glass material through node editor however this material was assigned to all three spheres. I confirmed that my selection is only on one sphere. What am I missing?