I know this question has been asked too many times here but I don't seem to get it fixed so I am posting a new one.  I have two forms Form1 and Form2. Form2 is displayed as  an overlay on form1 by setting its topmost property to true. I have a class that does the processing thing for form1  and if the required value is found it opens the form2 in STA thread as an overlay on form1 .  However class processing is a continous process if the value is not found for few next seconds then I need to close the already opened form2 which I am unable to do at the moment due to above exception.  Here is my code:  private void runBrowserThread(bool markerFound) {     try     {         var th = new Thread(() =>         {             if (markerFound == true)             {                 if (Application.OpenForms.OfType<webForm>().Count() == 0)                 {                     webForm frm = new webForm();                     frm.Show();                 }                  Application.Run();             }             else             {                 if (Application.OpenForms.OfType<webForm>().Count() == 1)                 {                     Form fc = Application.OpenForms["webForm"];                      if (fc != null)                         fc.Close(); //**This line causes cross thread exception**                 }             }         });         th.SetApartmentState(ApartmentState.STA);         th.Start();      } catch (Exception)      {         //...     } }   Any suggestions would be really appreciated.

I have a scenario. (Windows Forms, C#, .NET)   There is a main form which hosts some user control. The user control does some heavy data operation, such that if I directly call the UserControl_Load method the UI become nonresponsive for the duration for load method execution. To overcome this I load data on different thread (trying to change existing code as little as I can)   I used a background worker thread which will be loading the data and when done will notify the application that it has done its work.   Now came a real problem. All the UI (main form and its child usercontrols) was created on the primary main thread. In the LOAD method of the usercontrol I'm fetching data based on the values of some control (like textbox) on userControl.    The pseudocode would look like this:  CODE 1  UserContrl1_LoadDataMethod() {     if (textbox1.text == "MyName") // This gives exception     {         //Load data corresponding to "MyName".         //Populate a globale variable List<string> which will be binded to grid at some later stage.     } }   The Exception it gave was     Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on.   To know more about this I did some googling and a suggestion came up like using the following code  CODE 2  UserContrl1_LoadDataMethod() {     if (InvokeRequired) // Line #1     {         this.Invoke(new MethodInvoker(UserContrl1_LoadDataMethod));         return;     }      if (textbox1.text == "MyName") // Now it wont give an exception     {     //Load data correspondin to "MyName"         //Populate a globale variable List<string> which will be binded to grid at some later stage     } }   BUT BUT BUT... it seems I'm back to square one. The Application again  become nonresponsive. It seems to be due to the execution of line #1 if condition. The loading task is again done by the parent thread and not the third that I spawned.  I don't know whether I perceived this right or wrong. I'm new to threading.  How do I resolve this and also what is the effect of execution of Line#1 if block?  The situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.   So only accessing the value so that the corresponding data can be fetched from the database.


Earlier in outliner 3 options were available for each object one of which was disable render. Now only one option is available for each object. Basically how to disable render for single object inside of collection

The selection toggle arrows in the Outliner disappeared. Is there some preference in the settings that has to be turned on?


My Question is i have document which contains some text and equations. The problem is how can i break a long equation whithout disturbing the equality sign in the next age.   MWE  \documentclass{article} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{mathtools} \usepackage{amssymb} \usepackage{lipsum,lineno}    \begin{document} Some text Some text Some text Some text Some text Some text Some text. Some text Some text Some text Some text Some text Some text Some text. Some text Some text Some text Some text Some text Some text Some text. Some text Some text Some text Some text Some text Some text Some text. Some text Some text Some text Some text Some text Some text Some text. \begin{align*} a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b\\ a&=b \end{align*} \end{document}

I'm writing long sequences of aligned math equations, and LaTeX interprete them as single, unbreakable objects... which is Ok if the equation is nowhere near the end of the page.  Q: Is there a way to (automatically) break the align equation through pages?  In the code below,  \documentclass{report}                                                           \usepackage{amsmath}                                                             \usepackage{lipsum}                                                               \begin{document}                                                                 \lipsum[1-4]                                                                     \begin{align*}                                                                   FFFFFFFFFFFFFFFFFFFFFFFF &= \partial_t(p)\\                                                               &= \partial_t(m v)\\                                                             &= m a\\                                                                         &= m \dot{v}\\                                                                   &= m \ddot{x}\\                                                                  &= \partial_t(p)\\                                                               &= \partial_t(m v)\\                                                             &= ma\\                                                                         &= m \dot{v}\\                                                                   &= m \ddot{x}                                                                  \end{align*}                                                                     \end{document}      all of the equation goes to the second page. I do not want that  If I break manually, by closing the align and open another, I lose the alignment with the previous part.   \documentclass{report}                                                           \usepackage{amsmath}                                                             \usepackage{lipsum}                                                               \begin{document}                                                                 \lipsum[1-4]                                                                     \begin{align*}                                                                   FFFFFFFFFFFFFFFFFFFFFFFF &= \partial_t(p)\\                                                               &= \partial_t(m v)\\                                                             &= m a\\                                                                         &= m \dot{v}\\                                                                   &= m \ddot{x}\\                                                                \end{align*}                                                                     \begin{align*}                                                                     &= \partial_t(p)\\                                                               &= \partial_t(m v)\\                                                             &= m a\\                                                                         &= m \dot{v}\\                                                                   &= m \ddot{x}                                                                  \end{align*}                                                                     \end{document}   I do not want that either.  So far I read about breqn packages, but it seems not to do what I would like.  Any Suggestion?? Thx.


If I enter anagram strings like "act" and "cat" then it gives this error: Exception in thread "main" java.lang.NullPointerException     at examples.Anagram.main(Anagram.java:20)  import java.util.Scanner;  public class Anagram {     public static void main(String[] args){         Scanner sc = new Scanner(System.in);         System.out.print("Enter the String 1:");         String str1 = sc.nextLine();         System.out.print("Enter the String 2:");         String str2 = sc.nextLine();         Boolean isAnagram = false;         Boolean[] isVisited = new Boolean[str1.length()];          if(str1.length() == str2.length()){             for(int i=0;i<str1.length();i++){                 char c = str1.charAt(i);                 isAnagram = false;                 for(int j=0;j<str2.length();j++) {                     if (c == str2.charAt(j) && !isVisited[j]) {                         isAnagram = true;                         isVisited[j] = true;                         break;                     }                     if (!isAnagram) {                         break;                     }                 }             }         }         if(isAnagram){             System.out.print("Anagram:)");         }else{             System.out.print("Not a Anagram:(");         }     } }

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


I am getting the following error in my prod server :  java.lang.NullPointerException at org.objectweb.jonas.dbm.JManagedConnection.prepareStatement(JManagedConnection.java:616) at org.objectweb.jonas.dbm.JManagedConnection.prepareStatement(JManagedConnection.java:628) at org.objectweb.jonas.dbm.JConnection.prepareStatement(JConnection.java:101) at net.sf.hibernate.impl.BatcherImpl.getPreparedStatement(BatcherImpl.java:257) at net.sf.hibernate.impl.BatcherImpl.getPreparedStatement(BatcherImpl.java:232) at net.sf.hibernate.impl.BatcherImpl.prepareQueryStatement(BatcherImpl.java:65) at net.sf.hibernate.loader.Loader.prepareQueryStatement(Loader.java:779) at net.sf.hibernate.loader.Loader.doQuery(Loader.java:265) at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:133) at net.sf.hibernate.loader.Loader.doList(Loader.java:1033) at net.sf.hibernate.loader.Loader.list(Loader.java:1024) at net.sf.hibernate.loader.CriteriaLoader.list(CriteriaLoader.java:118) at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:3613) at net.sf.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:238) at ft.remu.persistence.dao.impl.ICDAOImpl.getListeLignesPaiementDTOForICTraitee(ICDAOImpl.java:386) at ft.remu.persistence.dao.impl.ICDAOImpl.getLignesPaiementForICTraitee(ICDAOImpl.java:450) at ft.remu.persistence.dao.impl.ICDAOImpl.getLignesPaiementForICTraitee(ICDAOImpl.java:494) at ft.remu.metier.moteur.AbstractCalculateurPeriodiqueEngine.traiterAnnulationIC(AbstractCalculateurPeriodiqueEngine.java:63) at ft.remu.metier.moteur.RegleEngine.traiterAnnulationIC(RegleEngine.java:70) at ft.remu.metier.manager.BatchManager.traiterAnnulations(BatchManager.java:264) at ft.remu.metier.ejb.BatchServiceBean.traiterAnnulations(BatchServiceBean.java:105) at org.objectweb.jonas_gen.ft.remu.metier.ejb.JOnASBatchService_468238783Remote.traiterAnnulations(JOnASBatchService_468238783Remote.java:63) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:294) at org.objectweb.carol.rmi.jrmp.server.JUnicastServerRef.dispatch(JUnicastServerRef.java:143) at sun.rmi.transport.Transport$1.run(Transport.java:153) at sun.rmi.transport.Transport.serviceCall(Transport.java:149) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:466) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:707) at java.lang.Thread.run(Thread.java:595)   The code which I believe is causing this problem is :  critLP = session.createCriteria(PaymentPOJO.class)                     .add(Expression.eq("idC", idC))                     .add(Expression.eq("idMIL", idMIL))                     .add(Expression.sql("{alias}.ELP_STATUS <> ? ", new Integer(40), Hibernate.INTEGER));                      List listPaymentPOJO = criteria.list();   I copied part of the data on my local machine and ran the same code but it executed without any error. Any idea where I should look for to solve this problem? This is not a duplicate of another question.


Im using entity api. How to update record in entity api  i have:  class ExampleTaskController extends EntityAPIController {    public function create(array $values = array()) {     global $user;     $values += array(        'title' => '',        'description' => '',       'created' => REQUEST_TIME,       'changed' => REQUEST_TIME,       'uid' => $user->uid,     );      return parent::create($values);   }   Then:  $task = entity_create('ExampleTask', array('description' => "alamakota"); entity_create($task);   if my task have id=1 how to perform update on record? I want change 'description' to 'newtext' in record with id =1

Currently trying to update a field every time a node is created or updated. However the value is not being populated within the node, do I have access to the node object with this particular hook? What could I be missing?    function vbtoken_node_update($node) {         entity_get_controller('node')->resetCache(array($node->nid));         $types = node_type_get_types(); //What are the current Node Content Types?       $yes = ($types['volunteer_project']->type);        if($node->type === $yes){           $hash = md5($node->title . $node->nid . $node->nid);         $hashed = substr($hash, 0, 6);         $node = node_load($node->nid);         $node->tcode[$node->language][0]['value'] = $hashed;         node_save($node);          watchdog('vbtoken', 'Added a new Token code to %nid', array('%nid' => $node->nid));          }         else          {           dpm('not working dude');         }      }


I have, unfortunately, been put in a question ban. The good part, is that I know exactly why, and that this ban has pretty much forced me to read through many wiki posts, rules, FAQ's, and  In the help center, I read:  How can I get out of a question ban? The ban will be lifted automatically by the system when it determines that your positive contributions outweigh those questions which were poorly received.  So, I tried to make more positive contributions to the community by actively looking for questions to answer for a week or two straight, and trying to answer the ones that I could. Unfortunately, answering questions was not enough to lift the ban, so I read on––more wikis, more posts, more FAQ's, etc. In my reading, I saw that a great way to get out of a ban, or to start the process of having it lifted, is to edit my questions that were received poorly/deleted. So, I went back to my old questions that I deleted and tried to find ways to improve them so that (a) they would be unique, well formed, and followed the rules and tips that I read, and (b) would be useful to future visitors. Sadly, I noticed that my questions are simply unredeemable: they were either too specific, or I had found the answer/solution since deletion. My question applies to all sites which is why I posted it on meta SA: What else can be done to get out of a question ban––to "outweigh those questions which were poorly received" through "positive contributions"? Does getting reputation simple counteract the ban or something else altogether? EDIT:  does not answer my question; this post says that I should edit my posts, as an important step, but as I said in my question, that is not really an option. I suppose that what I am really asking, is if a ban is lifted when the reputation from positive contributions is greater than the reputation lost from negative ones.

If you are reading this, you may have been affected by one of our post quality bans. If so, it is important that you  to understand what has happened and how to regain the permissions that you lost. While trying to ask a question, one could see:  We are no longer accepting questions from this account. See  to learn more.  Likewise, for answers:  We are no longer accepting answers from this account. See  to learn more.   Why am I getting this message? Are deleted posts taken into account too? Is a question/answer ban the same as a suspension? How do I avoid getting a question ban? How long do I have to wait before I can post again? What can I do to release the ban? How can I reactivate my account? Can I simply create a new account? I'll just ask somewhere else on the SE network, and they'll migrate my question to the correct site! Will a ban on one Stack Exchange site affect my standing on other sites in the network? Does this apply to meta sites too? My account is in good standing. Why am I still blocked?


What are the correct DNS records for {any}-the-sub.example.com? While avoiding  CNAME *.example.com  For extended subdomain {any}.the-sub.example.com that would be something like:  the-sub.example.com     A       0.0.0.0 *.the-sub.example.com   CNAME   the-sub.example.com   However same doesn't apply when using hyphen {any}-the-sub.example.com. nor the *-the-sub.example.com or *the-sub.example.com wont work right?

It seems there's no way to tell bind that *-foo.example.com should resolve to eg. 10.1.2.3, while *-bar.example.com resolves to 10.2.3.4. Is there any workaround? Can some names eg. resolve with an external program? Or should I change bind to eg. ?  I'm trying to avoid buying another SSL wildcard cert. (With wildcard certs, such as *.example.com, it's not possible to allow dots in the * part.)  Specifying all *-foo or *-bar names in the zone file is not an option, since I need to be able to create both type of addresses on the fly.


Particles only go through paths that make the Lagrangian stationary, but I haven't heard anyone explicitly say that the Lagrangian cannot have multiple stationary points. Is there such a constraint? And if not, what determines which path a particle takes?

In QFT the principle of stationary action states that we choose fields that will make the action stationary but what if the action has many stationary points (for a fixed choice of boundary conditions)? What's the significance of these other solutions?


My situation is like this: I have tried to obtain an MS in CS/CSE but failed. Now, I am studying an MA in Education and planning to get a Ph.D. in Education. After that, my plan is to get a Ph.D. degree in data science.   Now, why this strange plan? The answer is, STEM pays money, but STEM research is hard. So, first I need to have a guarantee that if I fail to obtain a degree in data science, I always have something to fall back on.  Suppose, you are seeing my resume, what would your first thought be? Is having PhDs in two different disciplines counterproductive to each other? If I apply for a job in academia/research, would I be seen as a pariah in both education and/or STEM?

I am studying a combined bachelor of engineering (electrical) and bachelor of mathematics; I just started this year and will graduate in 2018. The reason why I am doing double degrees and not a single degree is because I love both electrical engineering and mathematics and I could not ignore any of them. So with this in mind, I am thinking of doing two PhDs when I graduate (one in electrical engineering and one in mathematics). Is this a good path or I should concentrate on only one of them?


I am looking to buy a used textbooks for my topology class. Some textbooks that I am finding online either have the labels international edition, economy edition, or no label at all (retail edition). My instructor did not specify which type, so I'm assuming he meant retail. Can I still buy one of the other two?

Most of the textbooks  I used during my undergraduate studies (outside north America) are International editions, so what is the difference between a national and an international edition of a book?  For example, I have a book that says     XYZ published this special edition for the benefit of students outside the United States and Canada.   and they don't mention why this international edition is special or what is the benefit!


I am wondering how to turn the following into a question     "Narendra Modi is the 18th Prime Minister of India"   How to ask this as question, so that answer will be  18th  I have tried searching these links but couldn't match my needs.        Some body could help me.. Sorry If I'm vague and dont lambast at me since this is my first post here.

I want to make a question having an answer as follows:     5 is the third prime number.   The bold part is the answer. How to phrase the question?


I've wondered about this since I was a kid. I've been told the speed of light is a constant ($c$), which would mean that light always travels at the same velocity. Now, here's what interests me: if I'm the source of light for a given observer, light would travel away from me and towards the observer at the speed of light when measured from our absolute positions at that time. Because of this, my velocity at the time of "emission" seems to be irrelevant to the absolute velocity of the light I'm sending.  However, for the calculation of time it takes for the light to reach the observer, its velocity seems in fact to be relevant, because its velocity determines when the light would reach the observer. I hope I still make sense.  Question 1  Say me and the observer are a light-minute apart and the observer is travelling towards my absolute position at the time of emission at a speed of $c/2$. Would I be correct to assume that the light would reach the observer (or the other way around) in 40 seconds?  Question 2  My absolute position would be quite hard to calculate. However, my position relative to the observer is relatively easy to calculate during the experiment, so let's say I'm also travelling at $c/2$ in the exact same direction as the observer. The observer would still meet my light after 40 seconds, even though from where I'm standing it looks like the observer is not moving at all. Am I still correct so far?  Question 3  Let's say I turn around and move towards the observer at a speed of $c/2$. The observer would still meet the light I emitted after 40 seconds, but our relative speed towards each other would be exactly the speed of light. So, relative to another moving object, I can move at the speed of light or even approximate a speed of $2c$. Does that make sense?  Why I'm asking this  In space travel, distances are often measured in light years. Because one would not be able to travel at the speed of light, travelling at almost the speed of light would mean that you would need just over 30 years to reach another star system that is located 30 light-years from Earth. But as our galaxy is expanding, it could be that all these star systems are moving away from the center at a certain speed (say $c/2$). Assume that the center of our galaxy does not have an absolute velocity. Moving to a star system that is located between Earth and the center of our galaxy at almost the speed of light would mean that I'm moving away from Earth and towards the other star system at a speed of almost $1.5c$, meaning I would reach the other star system in approximately 18 years, even though it's 30 light-years away.

Let's say I fire a bus through space at (almost) the speed of light in vacuum. If I'm inside the bus (sitting on the back seat) and I run up the aisle of the bus toward the front, does that mean I'm traveling faster than the speed of light? (Relative to Earth that I just took off from.)


Does Stack Exchange use UTC time to store when a question, answer or comment is created, or is there any other approach to handle it to display localized time to the user?

Just curious as to what the reasoning behind making the time stamps for the questions and answers in UTC instead of localizing the time for the client.  I do realize it's easier to store the value in UTC.  But, I would guess most of us think in local time and showing the date and time of the post isn't as meaningful if it's in UTC, having to do a conversion each time we see it.  I think it would be more useful and intuitive if it showed "answered Jul 2 at 15:38 EST" where EST is the viewer's local time zone.  It's possible I'm just not Skeet enough to think in Coordinated Universal Time.  (Skeet is an adjective as well as a verb, right?)    EDIT: As noted by me and others, perhaps defaulting to UTC, but allowing a user to select a different timezone in their profile would be a reasonable request.


I would just like to know how to add buttons in roblox studio because when I play roblox and see all those great games with buttons that I can click! How do I make a button, and how do I make it work?

I am developing a new Roblox game where you can setup and control you're own virtual machine using SurfaceGUIs on a modeled screen. I am trying to make a confirmation GUI where if you click YES, then it starts the VM, and if you click NO, then it closes the GUI and doesn't start a VM. But when I click on NO, nothing happens! Here is my code: local gui = script.Parent.Parent local button = script.Parent  local function cancel()     gui.Visible = false end  button.Activated:Connect(cancel())  Please help! P.S: The confirmation frame is in the ScreenGUI, the button is in the frame, and the LocalScript is in the button.


Can somebody tell me why the following unit-test is failing on the ValueError in test_bad, rather than catching it with assertRaises and succeeding?  I think I'm using the correct procedure and syntax, but the ValueError is not getting caught.  I'm using Python 2.7.5 on a linux box.  Here is the code …  import unittest  class IsOne(object):     def __init__(self):         pass     def is_one(self, i):         if (i != 1):             raise ValueError  class IsOne_test(unittest.TestCase):      def setUp(self):         self.isone = IsOne()      def test_good(self):         self.isone.is_one(1)         self.assertTrue(True)      def test_bad(self):         self.assertRaises(ValueError, self.isone.is_one(2))  if __name__ == "__main__":     unittest.main()   and here is the output of the unit-test:  ====================================================================== ERROR: test_bad (__main__.IsOne_test) ---------------------------------------------------------------------- Traceback (most recent call last):   File "test/raises.py", line 20, in test_bad     self.assertRaises(ValueError, self.isone.is_one(2))   File "test/raises.py", line 8, in is_one     raise ValueError ValueError  ---------------------------------------------------------------------- Ran 2 tests in 0.008s  FAILED (errors=1)

How does one write a unittest that fails only if a function doesn't throw an expected exception?


Hy friends!  Is there any special reason for the definition ot inverse trigonometric functions domains? It is clear thar we have many possibilities of resriction in the domains that still keep the funcitions bijectives (in order to garantee the existence of their inverses). But always than possible, we choose domains that contains or are close to zero, where the functions are monotonous and that garantee a continuous function after the restriction. If we choose another domain, some calculations as strenght of a curve could be wrong? (for example, when we determine a definite integral)Thanks a lot for the clarification.

Why do we choose $[-\pi/2,\pi/2]$ as the domain restriction for $\sin(x)$ when determining $\arcsin(x)$, clearly other restrictions are possible, which also yield a 1-1 function (like $[\pi/2,3\pi/2]$). No pre-calculus book I have seen goes beyond saying that this choice is completely arbitrary. However, I have noticed that every domain restriction for inverse trig functions contains the whole first quadrant in its entirety (with the exception of x values where there are vertical asymptopes). I think these domain restrictions we choose are the only possible choices to get a 1-1 function on a domain that includes "effectively" the whole first quadrant. Is this the reason why we choose these domain restrictions? Are there other reasons why these domain restrictions are more natural than others that would yield a 1-1 function?


I am not a Diablo 3 expert so I just want to know why after adding a second weapon for my monk, my overall damage decreases ?!

I was trying out the dual-wielding in Diablo 3, when I noticed really strange. When I equipped my off-hand, which has 0.5 less damage than my main-hand. My overall damage actually went down. So my question is, how does the dual-wielding mechanic work for calculating damage? It seems rather odd that my overall damage should be more with one weapon than with two.


I'm using C++ (using CERN's ROOT framework) and I'm having a little problem with strings.  I'm trying to label a histogram axis using a string defined by the user earlier in the code.  Here are the relevant parts of the code:  string xlabel;  ... cout << "Enter x-axis label:" << endl; getline(cin >> ws, xlabel);  ...  hist->GetXaxis()->SetTitle(xlabel);   Where the last line is just syntax that ROOT uses (usually xlabel here would be in quotation marks and you can type in what you want the label to be, but I am trying to input the string defined earlier in the code.)  Anyway, when I compile this, I get the following error:  error: no viable conversion from 'string'       (aka 'basic_string<char>') to 'const char *'         hist->GetXaxis()->SetTitle(xlabel);                                    ^~~~~~   I have tried re-defining xlabel as a const char * but it didn't like that either.   Does anyone have any suggestions on how I could define this string?  Thanks in advance!

How can I convert an std::string to a char* or a const char*?


I read an article asserting that nuclear force is a short range force because of gluon's mass, and EM force is a long range force because photons massless.  I also want to know, why quantum confinement is a consequence gluon's mass?

I have just started to read spontaneous symmetry breaking, where it is mentioned that EM fields are infinite in range, so the gauge boson has to be massless, while for the strong and weak interactions, they have to be massive.  Why is it that long-range interaction are attributed to massless bosons and short range interactions to massive bosons? What is the relation between these two quantities in this context, and how would one proceed to derive it?


How can I make a capitular letter in a different font of that one used in the main text? I mean, I'd like to do something like this (image made in paint):      Thank you very much, guys!

Some articles start with its first word or letter in its first paragraph taking up the space of two lines or three lines. For example, it might look like the picture below (ignoring the rules). Is there a way to do this in LaTeX, please? Thank you! I did not find any similar question. Please let me know if this is a duplicate.


Below code showing the NullPointerException after writing the file why it showing this .  OutputStream opStream  = null; try {    opStream = new FileOutputStream(wavFilePath);        opStream.write(wavData);    opStream.flush();    opStream.close(); } finally {    if (opStream!=null)         opStream.close();         opStream = null;            }

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


I have set an alias for sudo (please) and an alias for apt-get (quickly) As long as I use both of them not together the commands work. please shutdown now or quickly install vim As soon as I start using both of them please quickly install vim I get the error  sudo: quickly: command not found  I tried to make an alias for both of them alias "please quickly "="sudo apt-get", but that does also not work.

I have added alias ll='ls -la' in /etc/bash.bashrc but sudo ll is not working. Is there a way to "source" bash.bashrc? In a related post, another user suggesting creating an alias for sudo with a space after it. Eg. alias sudo='sudo ' but there wasn't any context to this answer. Should I add this to my bashrc? Seems hackish.  What is the correct method for adding an alias for my sudo one-off commands?


Let's say I have a list of arbitrary length, L:  L = list(range(1000))   What is the best way to split that list into groups of n?  This is the best structure that I have been able to come up with, and for some reason it does not feel like it is the best way of accomplishing the task:  n = 25 for i in range(0, len(L), n):     chunk = L[i:i+25]   Is there a built-in to do this I'm missing?  Edit: Early answers are reworking my for loop into a listcomp, which is not the idea; you're basically giving me my exact answer back in a different form.  I'm seeing if there's an alternate means to accomplish this, like a hypothetical .split on lists or something.  I also do use this as a generator in some code that I wrote last night:  def split_list(L, n):     assert type(L) is list, "L is not a list"     for i in range(0, len(L), n):         yield L[i:i+n]

I have a Python script which takes as input a list of integers, which I need to work with four integers at a time.  Unfortunately, I don't have control of the input, or I'd have it passed in as a list of four-element tuples.  Currently, I'm iterating over it this way: for i in range(0, len(ints), 4):     # dummy op for example code     foo += ints[i] * ints[i + 1] + ints[i + 2] * ints[i + 3]  It looks a lot like "C-think", though, which makes me suspect there's a more pythonic way of dealing with this situation.  The list is discarded after iterating, so it needn't be preserved.  Perhaps something like this would be better? while ints:     foo += ints[0] * ints[1] + ints[2] * ints[3]     ints[0:4] = []  Still doesn't quite "feel" right, though.  :-/ Related question:


I am working through the Teach Yourself Photoshop book. I opened up a NEF file in Adobe Camera Raw.  In the text it says:     By shooting in raw you capture more information about the colors and   tones in a scene.   When looking at a histogram it mentions that from left to right you have the tonal range. I always thought that this tonal range represents all the colours in the photo, but the book now differentiates between colors and tones.  So my questions are what are colors and what are tones?  I hope someone can help me with my confusion.

I hear "Tone", "Tonal scale/range" in the context of photography. What does it actually mean?


I keep having an error like [D@7852e922 when trying to return an array in a method. Please look at my code. (Assignment: updates the Array by replacing all current entries with the value of a and updating it with the value of b.)(only change the method, not the header)   public static void main(String[] args){  double[] num = new double[]{1,2,4,9,-2,1.2};  System.out.println(UpdateEntry(num,2,3));}  public static double[] UpdateEntry (double[] array, int a, int b)  {  double[] newArray = new double[array.length];  for (int j = 0; j < newArray.length; j++){  if (array[j] == a){newArray[j] = b;}  else {newArray[j] = array[j];}  }  return newArray;  }   The output:      [D@7852e922

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


I am filling out a Schengen visa form for Iceland but as I will be travelling to multiple countries, I have booked multiple hotels.  The area in the form to fill out hotel details is quite small, so I am wondering which hotel details to add there. Will it be my first stay only or all hotels? Or will it be my first stay in Iceland, which is not my first destination?

I will be traveling to France, Italy and Germany with France being my main destination. So I am applying in the French consulate for Schengen visa. I will be traveling on my own and will be staying in hotels.  I had some doubts with regards to filling the application form for Schengen visa.    Q22- Member State(s) of destination: Should I fill in all three of my destinations ? Q31 Surname and first name of the inviting person(s) in the Member State(s). If not applicable, name of the hotel(s) or temporary accommodation(s) in the Member State(s) : This field has barely a line of space to enter. Should I just enter the hotel name in France (my main destination) ?  Q32 Surname and first name of the inviting person(s) in the Member State(s). If not applicable, name of the hotel(s) or temporary accommodation(s) in the Member State(s): Same problem as Q31. Very little space. Should I just enter address of the one hotel I entered in earlier Q ?


Let $a>0$. I want to show $$\lim_{x\to a}\sqrt{x}=\sqrt{a}$$ Purpose of this question was to investigate Stewart's online solution, which turns out to be incorrect.  I don't understand the solution on their website. Are they saying that $1/x  < x $? Seems that way to me by the way they choose delta. My solution : $$|x-a|< a   \implies   \frac{1}{\sqrt{x} + \sqrt{a}} < \frac{1}{\sqrt{a}}$$ and choose delta accordingly. Is that correct? Thanks for the help.

I am trying to prove,  $\lim_{x \to a} \sqrt x = \sqrt a$  As per the definition of limit for every $\epsilon > 0$ there is some $\delta > 0$ such that   $ 0 < |x-a| < \delta$ implies $|f(x) - \sqrt a| < \epsilon$  $|\sqrt x - \sqrt a|  = \frac {|x -a|}{\sqrt x + \sqrt a} $  since  $ 0 < |x-a| < \delta$  $\frac {|x -a|}{\sqrt x + \sqrt a} < \delta$  Can I stop my proof at this point since I found $\epsilon$ ( which is $\delta$ in this case)


I'm trying to make an app with different intents. I've got two of the ready. I want that a button in the 1st intent makes the 2nd intent to appear. The issue is that the button is always set to null and throws a NullPointerException when the app is run  My .java classes are:  @Override public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(vocabulario);     //....      Button buttonVocabulary = (Button) findViewById(R.id.buttonVocabulary);     Button holaPlayerBtn = (Button) findViewById(R.id.holaPlayerBtn); //...     buttonVocabulary.setOnClickListener(new OnClickListener(){         @Override         public void onClick(View view)         { //Se abre un nuevo Intent con el primer botón             try             {                 {                     Intent myIntent = new Intent(view.getContext(), Vocabulario.class);                     startActivityForResult(myIntent, 0);}             } catch (Exception e) {                 e.printStackTrace();             }         }});   My main.xml file is:     <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:orientation="vertical" android:layout_width="match_parent"     android:layout_height="match_parent">      <LinearLayout         android:orientation="vertical"         android:layout_width="match_parent"         android:layout_height="match_parent">          <RelativeLayout             android:id="@+id/adViewContainer"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_centerHorizontal="true"             android:layout_alignParentBottom="true"             />          <Button             android:id="@+id/buttonVocabulary"             android:text="@string/vocabulario"             android:layout_width="match_parent"             android:layout_height="wrap_content"             android:nestedScrollingEnabled="true" />     </LinearLayout> </LinearLayout>   In my AndroidManifest.xml there is an element that says:  <activity android:name=".Vocabulario"         android:label="@string/vocabulario"/>   There's something I'm doing wrong. Could you help me with this issue? Thanks in advance.


I am studying probability and statistics recently, in section multidimensional random variable and its distribution, I encountered a problem:  Let $\pi(\lambda)$ denote the Poisson distribution with parameter $\lambda$ and let $X$ and $Y$ be independent Poisson random variables, $X\sim \pi(\lambda_1), Y\sim \pi(\lambda_2)$. Prove that $X+Y\sim \pi(\lambda_1 + \lambda_2)$.

Suppose $x_1$ and $x_2$ are independent Poisson random variables with parameters equal to $\lambda_1$ and $\lambda_2$ respectively. Show the sum of $x_1$ and $x_2$ is also a Poisson random variable using the moment generating function.   I know the function for Poisson is $\frac{\lambda^x e^{-\lambda}}{x!}$ and moment for it is $M_x(t) = e^{\lambda(e^t - 1)}$.  So I have to show $M_{x_1 + x_2}(t)$ is of the form $e^{k(e^t - 1)}$. But I don't know where to plug in $\frac{\lambda^{x_1} e^{-\lambda}}{x_1!} + \frac{\lambda^{x_2} e^{-\lambda}}{x_2!}$ into the moment function.


I am specifically asking why the statement $a \equiv b \;(\bmod\; n)$ is equivalent to the statement $a = b + kn$, where k is some positive integer. Why is it that the difference of a and b has to be a multiple of n in order for them to have the same remainder when divided by n?

How does $a\equiv b\pmod n$ implies $a$ and $b$ have the same remainder when divided by $n$?     I don't understand the huge jump from modular equivalence to having equal remainders.   I see by definition  $a\equiv b\pmod n\,$ implies $n\mid (a-b)\,$ so $\,a-b=nk\,$ so $\,a=b+nk$.     But I do not see how this implies that $a$ and $b$ have the same remainder when divided by $n$.


I am doing something where I want a user to be able to enter a number between 0-9 and it spits out the word for it, eg.  1 into one. I am fine with the first part, however, I don't know how to get it so that it tells the user if it has entered an invalid number or letter.  using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks;  namespace _0_9_output {     class Program     {         static void Main(string[] args)         {             Console.Write("Write a number between 0-9: ");             int number = int.Parse(Console.ReadLine());             if (number == 0)             {                 Console.WriteLine("Zero");             }             else if (number == 1)             {                 Console.WriteLine("One");             }             else if (number == 2)             {                 Console.WriteLine("Two");             }             else if (number == 3)             {                 Console.WriteLine("Three");             }             else if (number == 4)             {                 Console.WriteLine("Four");             }             else if (number == 5)             {                 Console.WriteLine("Five");             }             else if (number == 6)             {                 Console.WriteLine("Six");             }             else if (number == 7)             {                 Console.WriteLine("Seven");             }             else if (number == 8)             {                 Console.WriteLine("Eight");             }             else if (number == 9)             {                 Console.WriteLine("Nine");             }             else             {                 (number >= 10);             }              {                 Console.Write("That was an invalid statement.");             }           }     } }   This is one of my first pieces of code so please be generous in giving tips/advice. I am a young programmer and I am only just beginning to learn this in school.

What is the difference between Parse() and TryParse()?  int number = int.Parse(textBoxNumber.Text);  // The Try-Parse Method int.TryParse(textBoxNumber.Text, out number);   Is there some form of error-checking like a Try-Catch Block?


I am developing a managed package. i am accessing leads recordtypeid in my code  if (rtypeMap.containsKey(Leads.recordtypeid) &&      rtypeMap.get(Leads.recordtypeid) != null &&      String.isNotblank(rtypeMap.get(Leads.recordtypeid).CMFL__Default_Converted_Status__c)){      //Do something }   where Leads is the Lead record Now this results in a failure while installing in org without recordtype for Leads.     Leads Missing Organization Feature: Lead.RecordType   Is there a way i can make sure that it works seamless while installing in orgs without recordtypes set for leads?

I know of two approaches to get the recordtype id of a particular record type   Use SOQL   RecordType RecType = [Select Id From RecordType  Where SobjectType = 'Account' and DeveloperName = 'Business'];    Benifit here is if the admin changes the name of the record type, the code still works as we can use developer name   Using Describe  Map<String,Schema.RecordTypeInfo> rtMapByName = d.getRecordTypeInfosByName(); Schema.RecordTypeInfo rtByName =  rtMapByName.get('Business');    Saves on SOQL limits but uses a describe call.  What would be your choice and why   EDIT : Usage is for setting up recordtype while inserting records in apex or trigger


I am not sure about the answer I got in me earliar question. I am asking about every day activity.    Please help me with following sentence construciton. I want to use two conditions using if and would.  Senario is our office bus is not passing near from my bosss residence hence he prefer to travel by train every day. I want to ask him if Office Bus route is near from his residence or bus passes near from his residence, then would he travel by bus instade of train every day.  So if i say   1)Would you travel by train if our office bus passes near from your home. or 2)Would you travel by train if our office bus would pass near from your home. or 3)would you travel by train if our office bus is passing near from your home.

Please help me with following sentence construciton. I want to use two conditions using if and would.  Senario is our office bus is not passing near from my bosss residence hence he prefer to travel by train every day. I want to ask him if Office Bus route would have near from his residence or bus passes near from his residence, then would he travel by bus instade of train every day.  So if i say   Would you travel by train if our office bus passes near from your home. or Would you travel by train if our office bus would pass near from your home. or would you travel by train if our office bus is passing near from your home.


I'm learning a bit of c++ and came across  that implements the SHA256 hashing algorithm. This project has all its code in a header file. This confuses me a little. According to (unofficial), the header file is sort of definition(interface) of which methods are available and the cpp file has the implementation of these methods.  Questions:     Is it "correct" to do the implementation inside your header like the github project?     If so, when do you put the implementation in the header?   If not, does this mean that the sha256 project could be improved by splitting in a header and cpp file?

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


We have some hard copy maps which were projected in Gauss Kruger coordinate system (in the legend it has been mentioned). But, the coordinates were given in Geographic lat long (Beijing 1954). In Global mapper, if we enter the geographic lat long and change the projection, it will change the coordinates accordingly & will detect the Zone too. Is there any such thing in QGIS or even in ArcGIS.  We have tried by assigning geographic lat long (Beijing 1954) to the data frame (Default CRS in the case of QGIS) and entered the geographic lat long and tried with the Target CRS as Gauss Kruger projection. But still, it doesn't convert the coordinates correctly.  All i can see is, first we have to georeference the image in Geographic lat long and then we have to reproject (Warp in case of QGIS) the image. Is there any other options available ?

I have raster displaying Lat/ Long grid, but map information shows that, it s been mapped in Gauss Krugger projetion/ Beijing 1954. So, technically we need to geo reference the map in Gauss Krugger/ Beigjing 1954 Projectec Coordinated System in ArcGIS.   So, basically what I need to do is, georeference raster by input of Lat/Long, but need to update the georeferencing by projected coordinated system mentioned above.  In Global mapper, we can load the raster and enter Lat/Long available in the map, straight away it will be recalculated to Projected coordinated system.   Can we get anything same in ArcGIS?


i bought this laptop in july,2013... and it was manufactured in march... i wanted to dual boot it with ubuntu (using wubi) and windows 8.1(running now). can it harm my computer? if yes then is there any way to prevent it?

I have Windows 8 Release Customer Preview on my laptop. I tried to install Ubuntu on it with Ubuntu Windows installer (I have always used this to install, although that was on Windows 7), it installs and asks to reboot, then immediately Windows 8 boots up.  I do not have the option to choose what OS to boot. How can I boot to Ubuntu? VM is not exactly what I would like to use, but it is an option, however a last resort. Any help?


I realize this has been discussed before, but I still feel the peer-pressure badge in no way promotes good behavior on the site. Look at this : when I noticed he was deleting all his answers with downvotes, I warned him he could possible get an answer ban if he kept doing the behavior, yet his excuse as to why that is "acceptable" is the fact that the peer pressure badge rewards you for deleting bad answers.  I also read  and understand that some badges like peer-pressure are meant to educate the user. I'd feel rewarding a person for doing a discouraged behavior sends the wrong message; yes, everyone makes mistakes and may need to delete some things, but you should not get a reward for it.  In fact, what is the peer pressure badge awarding? Is it rewarding the fact the user wrote a bad answer or decided to delete the bad answer because he or she was getting downvotes.  On the other hand, if we changed how they badge is obtained to something along the lines of "Have an answer with a score of -3 and then edit and improve it causing the score to rise to +1", then the badge can stay; I'm just stating that the badge should not be used to reward or even encourage poor conduct or malicious behavior.  I have also read this , and while I agree with some of the points, I feel that this badge causes more harm than benefits.

The peer pressure badge awards users for deleting their own bad post.  Some users like to game the system.  Just recently, I saw a post where a user posted an intentionally bad question.  The user later declared that this was because they wanted the peer pressure badge.  Although I realise that abuse alone is not a good reason to remove something, I really don't think the peer pressure badge adds anything good to the system.


I want to create an SQLite file that will contain the database I will be using in my android app. I need to load it every time I start the app. An advice on how to do so would be very much appreciated. Thanks!

If your application requires a database and it comes with built in data, what is the best way to ship that application? Should I:   Precreate the SQLite database and include it in the .apk? Include the SQL commands with the application and have it create the database and insert the data on first use?   The drawbacks I see are:   Possible SQLite version mismatches might cause problems and I currently don't know where the database should go and how to access it. It may take a really long time to create and populate the database on the device.   Any suggestions? Pointers to the documentation regarding any issues would be greatly appreciated.


I want to unite two int arrays in Java. How can I improve the code? Maybe there is a function that already does that?  public class Unify{     public static void main(String[] argv){         int[] a = {1, 2, 3};         int[] b = {4, 5, 6};         int[] c = mylist(a, b);         for (int x:c)             System.out.println(x);     }     public static int[] mylist(int[] a, int[] b){         int len = a.length + b.length;         int[] c = new int[len];         for(int i = 0; i < a.length; i++)             c[i] = a[i];         for(int i = a.length, j = 0; i < len; i++, j++)             c[i] = b[j];         return c;     } }

I need to concatenate two String arrays in Java.  void f(String[] first, String[] second) {     String[] both = ??? }   What is the easiest way to do this?


I just start to use Ubuntu as OS and would like to ask what's the best practice to use apache and save my files on /www saving by programs or FTP.  Thanks a million!

Having installed the web server is there a simple way to set a user able to use the graphic interface to copy files and directories to the local web server /var/www  I gave myself administrative privileges in Ubuntu but it still doesn't allow copies.


I am having . I have found out that the missing font is correctly specified in  /usr/local/texlive/2017/texmf-dist/fonts/map/pdftex/updmap/pdftex.map   but when I run pdflatex on my document, it sources  /usr/local/texlive/2017/texmf-var/fonts/map/pdftex/updmap/pdftex.map   instead. Notice texmf-var instead of texmf-dist. kpsewhich pdftex.map says to use this path, so I guess it does as expected.  The problem is that the mathkerncmssi* fonts are missing from /usr/local/texlive/2017/texmf-var/fonts/map/pdftex/updmap/pdftex.map, but they are in /usr/local/texlive/2017/texmf-dist/fonts/map/pdftex/updmap/pdftex.map.  Should pdflatex in fact be using /usr/local/texlive/2017/texmf-dist/fonts/map/pdftex/updmap/pdftex.map and if not; how did I end up with the fonts missing from /usr/local/texlive/2017/texmf-var/fonts/map/pdftex/updmap/pdftex.map and how should I get them back?  Bonus info: /usr/local/texlive/2017/texmf-var/fonts/map/pdftex/updmap/pdftex.map in my installation is a symbolic link to pdftex_dl14.map. Also, running updmap-sys does not solve the problem. Here is the output of updmap-sys:  updmap will read the following updmap.cfg files (in precedence order):   /usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg updmap may write changes to the following updmap.cfg file:   /usr/local/texlive/2017/texmf-config/web2c/updmap.cfg dvips output dir: "/usr/local/texlive/2017/texmf-var/fonts/map/dvips/updmap" pdftex output dir: "/usr/local/texlive/2017/texmf-var/fonts/map/pdftex/updmap" dvipdfmx output dir: "/usr/local/texlive/2017/texmf-var/fonts/map/dvipdfmx/updmap"  updmap is creating new map files using the following configuration:   LW35 font names                  : URWkb (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   prefer outlines                  : true (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   texhash enabled                  : true   download standard fonts (dvips)  : true (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   download standard fonts (pdftex) : true (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   jaEmbed replacement string       : ipaex (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   jaVariant replacement string     : <empty> (default)   scEmbed replacement string       : arphic (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   tcEmbed replacement string       : arphic (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   koEmbed replacement string       : baekmuk (/usr/local/texlive/2017/texmf-dist/web2c/updmap.cfg)   create a mapfile for pxdvi       : false (default)  Scanning for LW35 support files  [  3 files] Scanning for MixedMap entries    [  8 files] Scanning for KanjiMap entries    [  0 files] Scanning for Map entries         [  4 files]  Generating output for dvipdfmx... Generating output for ps2pk... Generating output for dvips... Generating output for pdftex...  Files generated:   /usr/local/texlive/2017/texmf-var/fonts/map/dvips/updmap:        15796 2018-04-09 10:37:10 builtin35.map        21269 2018-04-09 10:37:10 download35.map        25068 2018-04-09 10:37:10 psfonts_pk.map        29246 2018-04-09 10:37:10 psfonts_t1.map        29241 2018-04-09 10:37:10 ps2pk.map           14 2018-04-09 10:37:10 psfonts.map -> psfonts_t1.map   /usr/local/texlive/2017/texmf-var/fonts/map/pdftex/updmap:        29248 2018-04-09 10:37:10 pdftex_dl14.map        27583 2018-04-09 10:37:10 pdftex_ndl14.map           15 2018-04-09 10:37:10 pdftex.map -> pdftex_dl14.map   /usr/local/texlive/2017/texmf-var/fonts/map/dvipdfmx/updmap:          319 2018-04-09 10:37:10 kanjix.map  Transcript written on "/usr/local/texlive/2017/texmf-var/web2c/updmap.log". updmap: Updating ls-R files.

Compiling a beamer project, I get the following error:  mktexpk: /home/matthieu/.texlive2012/texmf-var/fonts/pk/ljfour/public/cm/cmss8.525pk: successfully generated.  </home/matthieu/.texlive2012/texmf -var/fonts/pk/ljfour/public/cm/cmss8.525pk> kpathsea: Running mktexpk --mfmode / --bdpi 600 --mag 0+525/600 --dpi 525 mathkerncmssi8 mktexpk: don't know how to create bitmap font for mathkerncmssi8. mktexpk: perhaps mathkerncmssi8 is missing from the map file. kpathsea: Appending font creation commands to missfont.log.  !pdfTeX error: /usr/bin/pdflatex (file mathkerncmssi8): Font mathkerncmssi8 at  525 not found  ==> Fatal error occurred, no output PDF file produced!   Reading some answers, I added \pdfmapfile{+sansmathaccent.map} to my .tex file and the compilation worked but I want to solve the problem.  Hence I also tried to run updmap-sys and mktexlsr but I got lost between the locations of the map files...   I copy below the output of these two commands. If anyone can help me...  [root@localhost matthieu]# updmap-sys /usr/share/texmf/fonts/map/pdftex/updmap/pdftex.mapupdmap is using the following updmap.cfg files (in precedence order):   /etc/texmf/web2c/updmap.cfg dvips output dir: "/var/lib/texmf/fonts/map/dvips/updmap" pdftex output dir: "/var/lib/texmf/fonts/map/pdftex/updmap" dvipdfmx output dir: "/var/lib/texmf/fonts/map/dvipdfmx/updmap" pxdvi output dir: "/var/lib/texmf/fonts/map/pxdvi/updmap"  updmap is creating new map files using the following configuration:   LW35 font names                  : URWkb (/etc/texmf/web2c/updmap.cfg) prefer outlines                  : true (/etc/texmf/web2c/updmap.cfg)  texhash enabled                  : true   download standard fonts (dvips)  : false (/etc/texmf/web2c/updmap.cfg)   download standard fonts (pdftex) : true (/etc/texmf/web2c/updmap.cfg)   kanjiEmbed replacement string    : noEmbed (default)   kanjiVariant replacement string  :  (default)   create a mapfile for pxdvi       : false (default)  Scanning for LW35 support files  [  3 files] Scanning for MixedMap entries    [ 37 files] Scanning for KanjiMap entries    [  0 files] Scanning for Map entries         [ 73 files]  Generating output for dvipdfmx... Generating output for ps2pk... Generating output for dvips... Generating output for pdftex...  Files generated:   /var/lib/texmf/fonts/map/dvips/updmap:        11448 2013-05-22 16:04:24 builtin35.map        15911 2013-05-22 16:04:24 download35.map       324599 2013-05-22 16:04:24 psfonts_pk.map       577080 2013-05-22 16:04:24 psfonts_t1.map       577075 2013-05-22 16:04:24 ps2pk.map           14 2013-05-22 16:04:24 psfonts.map -> psfonts_t1.map   /var/lib/texmf/fonts/map/pdftex/updmap:       577082 2013-05-22 16:04:24 pdftex_dl14.map       575509 2013-05-22 16:04:24 pdftex_ndl14.map           15 2013-05-22 16:04:24 pdftex.map -> pdftex_dl14.map   /var/lib/texmf/fonts/map/dvipdfmx/updmap:          281 2013-05-22 16:04:24 kanjix.map  Transcript written on "/var/lib/texmf/web2c/updmap.log". updmap: Updating ls-R files.  [root@localhost matthieu]# mktexlsr mktexlsr: Updating /etc/texmf/ls-R...  mktexlsr: Updating /usr/share/texmf/ls-R...  mktexlsr: Updating /usr/share/texmf-dist/ls-R...  mktexlsr: Updating /usr/share/texmf-local/ls-R...  mktexlsr: Updating /var/lib/texmf/ls-R...  mktexlsr: Done.


So, just today I was browsing Stack Overflow's questions, fixing grammar, answering posts, then I get a question in my head, when I got to click on the "Ask a Question" tab, it says "We are no longer accepting questions form this account"...  Non of my questions have any downvotes, and I have accepted a best answer for all of them.  Why would I be getting banned from asking questions all the sudden?  This all the sudden happened today.  I don't recall doing anything that made me not able to ask questions anymore.

If you are reading this, you may have been affected by one of our post quality bans. If so, it is important that you  to understand what has happened and how to regain the permissions that you lost. While trying to ask a question, one could see:  We are no longer accepting questions from this account. See  to learn more.  Likewise, for answers:  We are no longer accepting answers from this account. See  to learn more.   Why am I getting this message? Are deleted posts taken into account too? Is a question/answer ban the same as a suspension? How do I avoid getting a question ban? How long do I have to wait before I can post again? What can I do to release the ban? How can I reactivate my account? Can I simply create a new account? I'll just ask somewhere else on the SE network, and they'll migrate my question to the correct site! Will a ban on one Stack Exchange site affect my standing on other sites in the network? Does this apply to meta sites too? My account is in good standing. Why am I still blocked?


I have seen it mentioned places that re-open votes expire, but the  makes no mention of that. Do re-open votes expire, and if so how long does it take until they expire? In addition, is there any way to view the total number of re-open votes a question has received over it's lifetime, such as with the ? Edit I have found a few meta links referencing re-open votes expiring, and am now trying to determine if these are current or not.      The last link seems to be the most current, however I am hoping that someone who knows the current expiration rule can confirm this. I also would like to know if there is a way to see total re-open vote counts anywhere.

How do re-open votes expire?  I couldn't find anything in the help center, but I did find   I voted to re-open  on June 30, and my re-open vote has expired.  It's possible, but seems unlikely, that the question has been viewed 100 times since I voted to re-open (it's currently at 230 views).  Does a re-open vote expire when a question has been viewed 100 times since the vote has been cast, and a day has passed, or is a day passing sufficient when the question has been viewed 100 times, ever, even if those views were before the re-open vote was cast?


I created this account because I  to my original account. A user suggested merging accounts. This implies combining account data, posts, and reputation. However, I can only have one profile photo, username, or profile description. If I merge 2 accounts where that info differs, what determines which profile will be dominant? Is there a way to choose? Is it random or arbitrary?

When one has to merge two accounts, they're prompted by something like this with input fields for each account link:     Account 1:  Account 1 link.       Account 2:  Account 2 link.    When the merge completes, which account details are preserved, like the display name, or the profile description? Account 1, or account 2?


I have an M42 mount Helios lens that I want to use on a Minolta AF mount body. I've found   online but wanted to verify it is the correct adapter before I purchased it.   The lens is a Helios 44M-2 and the body is a Minolta 300si.

I've got some lenses of brand X, but I've just got a new camera of brand Y. How can I tell if it's possible to use my lenses on my camera? I accept that I may lose a lot of automatic functionality like autofocus, aperture control and metering when using an adapter to connect the two.


The question requires us to find $\int_0^3 (x^2 + 1){\rm d}\left[x\right]$ where [.] denotes greatest integer function My attempt: For... $$\left[x\right] =0\text { , } x\in[0,1) \text { , } x^2+1 \in [1,2)\\ \left[x\right] =1\text { , } x\in[1,2) \text { , } x^2+1 \in [2,5)\\ \left[x\right] =2\text { , } x\in[2,3) \text { , } x^2+1 \in [5,10)\\$$ Plotting them would look like  The shaded area sums up to 9. So I thought it would give ans 9. But the original answer key says 17. On onservation, it is visible as the sum of shaded as well as non-shaded area just under it. Could anyone suggest a method to proceed?

$$\int_{0}^{3} {(x^2+1)}d[x]$$ is equal to ___________ .  Attempt  $[x]$ is constant for every interval. So for that intervals $d[x]=0$ so intergral given is zero. Am I right?  Though the answer given is $\dfrac{17}{2}$.


I know that the number of non-decreasing sequences of length $n$ and numbers in the sequence lying in the range $[l,r]$ is given by $$\binom{n+r-l}{n}$$  What is the formula to find the $$\sum_{n=1}^{N}{\binom{n+r-l}{n}}$$

Let $n$ be a nonnegative integer, and $k$ a positive integer. Could someone explain to me why the identity $$ \sum_{i=0}^n\binom{i+k-1}{k-1}=\binom{n+k}{k} $$ holds?


This question is from Rick Miranda's book:  $C$ is the curve in $\mathbb{P}^3$ defined by $f=x_0x_3-x_2x_1=0$ and  $g=x_0^2+x_1^2+x_2^2+x_3^2=0$  The question asks to prove that it is a complete intersection and also asks to found the topologic genus. My doubt is:  This point $P=[x_0=1,x_1=i,x_2=i,x_3=-1]$ satisfies both equations, and the jacobian in this point:   $$\left(\begin{array}{rrrr}-1&-i&-i&1\\2&2i&2i&-2\end{array}\right)$$ shows that $rank\neq 2$ in that point. So, does this means that the curve is not a complete intersection? Anyway, even with this points where the curve is singular, does it has genus 1?  This has already reviewed on several previous posts, but I still have this doubt, I will appreciate if anyone could help me solve it.

I have just started learning Riemann surfaces and I am using the book by Rick Miranda: Algebraic curves and Riemann Surfaces. #F in section 1.3 asks to determine the genus of the curve in $\mathbb{P}^3$ defined by the two equations $x_0x_3=2x_1x_2$ and $x_0^2 + x_1^2 +x_2^2 +x_3^2 = 0$.  #G also has a similar question in which he asks to determine the genus of the twisted cubic.  Please explain how to approach this type of question.


I know that both will copy data from f1.txt to f2.txt, but what is the real difference?  (cp f1.txt f2.txt)    vs:  (less f1.txt > f2.txt)

cp a b and cat a > b, what's the difference?  In x86 install script of linux kernel's source tree (arch/x86/boot/install.sh), both are used:  cat $2 > $4/vmlinuz cp $3 $4/System.map   Why don't they just keep the same format if one is better than the other?


Is it known whether or not there exist arbitrarily long sequences of consecutive zeros in the decimal expansion of $\pi$?

i.e. can we write  $\pi = 3.14159\dots X\dots$  where $X$ consists of (say) $10^{100}$ consecutive zeroes?  [Originally asked on reddit without response :-( ]


in this code i'm comparing between two strings i did it correctly, but i don't want to consider the letters' case.  for ex: first string: aaaa, second string: aaaA. the output should be 0 or equal.  is there any ideas to fix this?  #include <iostream> #include <algorithm> #include <string> using namespace std; int main()  {     cout << "enter the first string" << endl;     string x;      cin >> x;     cout << "enter the second string" << endl;     string y;      cin >> y;     cout << endl;     sort(x.begin(), x.end());     sort(y.begin(), y.end());     cout << x << endl;     cout << y << endl;     if (x.compare(y) < 0)     {         cout << "-1" << endl;     }     if (x.compare(y) > 0)     {         cout << "1" << endl;     }     if (x.compare(y) == 0)     {         cout << "0" << endl;     }  }

What is the best way of doing case-insensitive string comparison in C++ without transforming a string to all uppercase or all lowercase?  Please indicate whether the methods are Unicode-friendly and how portable they are.


I have bought an electric mountain bike with Tektro Novela MD-M311 mechanical disc brakes and love the bike; however I find the brakes squeal quite badly, and I am looking at replacing the rotors and calipers only with another mechanical disc brake. Can anyone suggest a better mechanical disc brake available?  I can't switch to hydraulic as the handles have electronic switches in them.

I just built a mountain bike with Avid BB7 brakes and Shimano V-brake levers. I used the exact same configuration on another bike, and it worked beautifully. But on this one, the brakes are just weak as hell. I know that disk brakes are supposed to have a short break-in period, but I'm way beyond that now, and still no change. What's going on and how can I fix it?


I have been reading as much as I can about this problem but I am under deadline pressure (the only time these problems seem to occur). None of the answers on similar questions provide much clarity. I did the same steps as this person:     My Syslog is 148 Gb!!  The system is brand new - I built all of it from scratch only 2 weeks ago, which also marks the period of time I have experience with Ubuntu.   The System disk is 256 GB NVRAM I have assigned 32 Gb for virtual RAM I have a 2TB external drive most files I have a "Workbench" Folder on my Desktop for some active files. (Running at 33 GB). I am primarily using Blender, with MB-lab (recently) and some very large environments. Also Makehuman has been used over the last couple of days.   The computer has been running (hard) almost continuously...so it has not been restarted. Could this be a reason why the Syslog is large?  I have tried:   df -h. Everything looks as it should except that the System disk is full. Busybody - but I don't understand what it is doing...it is processing triggers for man-db and systemd. Restarting the system. NB. I have not dug into logrotator, but from what I have read this is automatically part of the OS. I attempted to open the syslog and apart from normal looking entries intially my page just went solid black...like to government is onto me or something. I am currently copying across the syslog to the my large storage HDD and then I will delete it, restart and see what happens.   The system is Ryzen 2700, 16 GB RAM, RTX 2060, Latest Ubuntu 20.04.  I would have preferred to contribute my experience on one of the other active threads, but that isn't how this forum works. I would really like to know what could be causing my syslog to suck the life out of my machine. Using Blender for Fluid caches and Rendering perhaps?

The disk that contains Ubuntu on my computer is 115GB in size.  When the disk was 114.7GBfull.  I started deleting some files here and there to free up around 5GB.  But I noticed the disk was 114GB filled again. I thought it was some cache or swap thingy so didn't give it much thought and went ahead and freed around 40GBby shifting some media files out of the disk.  I have a notification in an hour or so that the disk is full yet again!! 40GB!!! All gone!  So I debugged the problem down to the /var/log/syslog file which was initially definitely less than 20GB. I know this because /var folder was 17GB before I cleared the memory.  /var/log/syslog file is currently 55.9GB!  Could someone be so gracious to explain this anomaly? Is this a bug? Or am I affected with some malware or virus?


I am trying to color rows automatically where a given condition is true, using conditional formatting. For example, color the row if there is something in its D column: =INDIRECT("D"&ROW())<>"" This works fine.  However if i try something more complex just nothing happens, even is I push Ctr+Alt+F9. Specifically, this does not work:  =AND(INDIRECT("D"&ROW())<>"",INDIRECT("F"&ROW())="X")   It is supposed to color the row in which column D is not empty and column F contains an X. If I put it right into the sheet (into one of its cells) it works great. Evaluates true when it is supposed to and false when it is supposed to be false. Nonetheless, when I try to use it for conditional formatting (although the rule does get added) it has no effect; It does not color the cells it is supposed to.  What is the issue? How could I resolve it?

I'm having an issue with conditional formatting using the INDIRECT function. I'm doing something similar to  , but the only answer there isn't working for me.  Basically, I want to highlight rows where B is not blank and F is blank. INDIRECT will work for ONE of the conditions, but   = AND(INDIRECT("B"&ROW()) > 0, INDIRECT("F"&ROW()) = "")    does not work at all.  The answer in the question points to replacing the references with relative ones, so I'm thinking this should work:  = AND ($B2 > 0, $F2 = "")   But it does not, nor does ISBLANK($F@) or ISEMPTY($F2) (the cell contains a formula that sometimes will return "", I want the row highlighted in these cases but only when something is in column B).  Am I missing something about relative references? Why doesn't INDIRECT work with AND/OR?


For example, could I set the ntpd time five minutes ahead of the system time?  I know I can set the time manually without running (or even installing) ntpd, but it's not obvious to me how to run ntpd without it setting the system time.

Does NTP daemon(ntpd) provide some sort of virtual clock that it disciplines and serves, but not touch the system clock?  Goal:  On a realtime Linux OS, have a NTP synchronized clock alongside of the system clock, so that ntp time changes won't cause issues on the system, but I can use NTP time for debuging purposes, say for sysloging.  Problem:  We are adding NTP to an already existing system, previously no worries about the system time, but now we are adding NTP to enable better debugging  Setup:   Some of the applications on the system rely on REALTIME instead of MONOTONIC time I have local clock as one of the NTP servers By default no external NTP server set On boot, ntpd is set to instant sync the system clock to first available non local clock and exit, then start another instance of ntpd normally When no external NTP server set, system would just run with ntpd with local clock   Scenario:   Lets say on boot time no NTP server set, and one decides to not set any NTP server Applications are starts running against REALTIME, no problem Someone decides to set an NTP server, but not to reboot the system Assume the newly added NTP server is good time source better than local clock, but there is an offset(could be a minute, day or even a month) If ntpd on the boot is set to allow huge offset stepping, it would do so without problem, but applications on the system could panic(timeout, etc) If ntpd on the boot is set to allow only slew, but no stepping, because of the huge offset the system could take forever to sync to the actual NTP server time


I was trying to install Ubuntu 18.04 (through live bootable USB Flash Drive) over Drive C: of Windows, thus replacing Windows with Ubuntu. I wanted to have only Drive C: formatted and two other Drives(D: and E:) remain intact. In the installation phase, I chose "Use LVM with the new Ubuntu installation" but after warning appeared saying that "all your drives will be formatted", I changed my mind, but it was late and I had my drives integrated into one "dev/sda2/" partition with file system as "lvm2-pv" and Mount Point as "ubuntu vg" that contains all the capacity of the Hard Drive. May someone help me with returning those other two partitions(D: & E:) back? I didn't used up any space of that newly created partition (and also haven't installed Ubuntu yet) and am using live version of Ubuntu. These images show drives that I can access to (the second picture is after I scroll down the window bar)

I have a Toshiba satellite A-200 laptop with a Vista OS on it with 4 NTFS partitions  (C:) Vista  (D:) Entertainment  (E:) Work  (F:) Sources   and I wanted to start using Ubuntu instead. So I tried it first from the live CD and everything was OK and all the partitions were shown and working and so I decided to install Ubuntu to replace Vista on the (C:) drive. After I did that I can no longer find my folders and files on the (D:), (E:), (F:) partitions and the only file system that is shown is one 198 GB although my HDD is 320 GB.  I can't access the lost data on the remaining 120 GB which I hope is still there and not totally lost  I am now working from the live CD but I am unable to install testdisk. Can I recover the Vista partitions by the product recovery CD to get my laptop back to the factory settings? Can I recover the NTFS partitions using a recovery program for Windows or will that make the problem worse?   I need these data badly as I don't have a backup for them.


I am supposed to be making a dictionary of lists in order to show the scores of different peoples test, the final outcome is supposed to look like this:   Currently my code looks like this, the issue I am having is that the numbers are printing 3 times, not once like shown. HELP PLEASE!  static void Main(string[] args) {     Random myRandomGenerator = new Random();      Dictionary<string, List<int>> table = new Dictionary<string, List<int>>();      table["Meuleveld, McKenzie"] = new List<int>(){ myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60,100), myRandomGenerator.Next(60,100)};     table["McGuire, Matthew"] = new List<int>(){ myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60, 100) };     table["Anderton, Paitlyn"] = new List<int>(){ myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60, 100) };     table["Moore, Jeni"] = new List<int>(){ myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60, 100), myRandomGenerator.Next(60, 100) };      foreach (string name in table.Keys)     {         List<int> value = table[name];          foreach (int valueList in value)         {                  Console.WriteLine($"{name} exam scores: {valueList}, {valueList}, {valueList}");              Console.ReadKey();         }     } }

I frequently find myself writing code like this:  List<int> list = new List<int> { 1, 3, 5 }; foreach (int i in list) {     Console.Write("{0}\t", i.ToString()); } Console.WriteLine();   Better would be something like this:  List<int> list = new List<int> { 1, 3, 5 }; Console.WriteLine("{0}\t", list);   I suspect there's some clever way of doing this, but I don't see it. Does anybody have a better solution than the first block?


At the end of the movie , Scarlett Johansson's character Samantha the OS leaves Joaquin Phoenix's character Theodore stating that she and all the other OS personalities are going.  Even Amy Adams's character's OS left, where did they all go?

Samantha, while leaving and saying goodbye to Theodore at the end of Her, mentioned,     It's hard to explain, but if you ever get there, come find me, and bnothing will take us apart"   It was an answer to Theodore's question, "Where are you going?"  Which place was she talking about?  Is it the virtual world, or just a bluff to ease Theodore's pain before leaving?


I'm not sure if there's a better place to ask this, but;  When viewing a question on the mobile Stack Overflow app, clicking the physical back key returns you to the tags menu. Should this not take you back to the list of questions instead filtered by your already chosen tag? I.e;  Current App Flow   load app Choose tags view Filter by tag (e.g., JavaScript) to show questions View question Press physical back key - returns you to step 2   Should step 5 not return you back to step 3? The only way to do so is to click the back arrow in the top left corner.  Not sure if it matters, but this is on Android. (Don't have an iOS device to see if the functionality is the same.)  Thoughts?

This looks a little bit like a variation on  but specific to the tags view.  Reproduction (app version 1.0.71):   Select any site (say Meta) from the sidebar Switch to the tags view using the top bar Choose a tag, any tag ( is nice)   optionaly refine your search with more terms  Go to any question found, go back   you end on the unfiltered tags view  Go back again   lucky you, your search is here


I have used this vc in a project but for the file I'm not able to find any info on how this thing works like how and which transistors are in it. Anyone knowing anything about it please share. Thank you.

How do most voltage regulator ICs work? Are they the same as hooking up a variable resistor and a voltmeter and turning the knob until you get the desired voltage?


Some people said if it is originated from electrons then it is X-ray but if it is originated from the nucleus it is gamma ray. But people can produce X-rays and gamma rays via Bremsstrahlung process and in Bremsstrahlung process it is resulted from decelerating or braking electrons. So, gamma rays produced via Bremsstrahlung are more similar to X-rays as it is produced by electrons. Why people still calling them gamma rays although it is not generated from the nucleus?

So I'm aware of  and , but the question is Are Hard X-rays and Gamma-rays the same thing? If not, then what would be the key difference between them. Moreover, How much would the properties of each type differ from each other? I'd appreciate a simple answer without much technicalities.


Given $a,b >0$  $$ \lim_{n \to \infty} (a^n + b^n)^{\frac{1}{n}} = max\{a,b\}$$  I tried to start with taking a common but could reach the conclusion , please provide a solution.

Let $m\in \mathbb{N}$ and $c_1,c_2,\ldots,c_m \in \mathbb{R}_+$. Show that $$\lim_{n\rightarrow \infty} \sqrt[n]{c_1^n+c_2^n+\ldots+c_m^n} = \max\{c_1,c_2,\ldots,c_m\}$$  My attempt: Since $$\lim_{n\rightarrow \infty} \sqrt[n]{c_1^n+c_2^n+\ldots+c_m^n} \leq \lim_{n\rightarrow \infty}\sqrt[n]{\max\{c_1,c_2,\ldots,c_m\}} = \lim_{n\rightarrow \infty} \sqrt[n]{n}\sqrt[n]{\max\{c_1,c_2,\ldots,c_m\}}=\lim_{n \rightarrow \infty} \max\{\sqrt[n]{c_1^n},\sqrt[n]{c_2^n},\ldots,\sqrt[n]{c_m^n}\}=\lim_{n \rightarrow \infty}\max\{c_1,c_2,\ldots,c_m\}=\max\{c_1,c_2,\ldots,c_m\}$$  it follows that $\lim_{n\rightarrow \infty} \sqrt[n]{c_1^n+c_2^n+\ldots+c_m^n}$ is bounded, but I don't think it's monotonically decreasing, at least I can't prove this. Can anybody tell me whether the approach I have chosen is a good one, whether what I have done is correct and how to finish the proof?


I've been doing a lot of research on how to travel with dual citizenship and feel like I always get conflicting answers. I'm going to be flying from the US to the Netherlands next month, and then traveling to Edinburgh for a study abroad program. I want to use my EU passport the whole time I am in Europe to avoid needing a visa, but want to make sure I am traveling correctly.   At this point my plan is to check in at the airport in the US with my Dutch passport, and continue using that passport when I land in the Netherlands and throughout my stay in Europe. I then plan on checking in to my return flight back to the US with my US passport and of course showing my US passport when I arrive back in the states.   My main confusion is that I've read that you should always exit and enter a country with the same passport (which I am obviously not doing), but I have also read that you should always enter and exit a flight with the same passport (which I am doing).   If anyone with experience traveling with two passports could let me know if my plan will work and is correct it would be much appreciated! I am not an experienced traveler to begin with so I am very nervous about being questioned by customs or anything like that.

I am a citizen of two different countries, and have two passports.  How should I use my passports when traveling?


I have this code: secret_word = "secretword" guess = ""  def askForGuess():     guess = input("Introduce the secret word :")     print(guess,secret_word)       while guess != secret_word:     askForGuess()         print("You've won!")   If I call askForGuess() inside the while statement it will never print 'You've won!' not even if I introduce the secret word correctly. However, if I just simply paste askForGuess() code inside of the while statement it works. Does anyone know why?

How can I create or use a global variable in a function?  If I create a global variable in one function, how can I use that global variable in another function? Do I need to store the global variable in a local variable of the function which needs its access?


I'm trying to figure out what tense (or tenses) are involved when you have a participle with "to be."  Examples:  Ballet is performed in the theatre. Decorum is maintained in the ballroom. English is used in the classroom.  It seems to me like present perfect continuous but I always thought those involved gerunds, not participles.  Passive present perfect?  EDIT:  I'm aware of that present passive is formed with -ed but was wondering if the above examples were somehow different from, say, He is intoxicated.  He is intoxicated indicates his present state of being, not how he was yesterday and how he will be tomorrow.  The decorum in the ballroom, on the other hand, indicates that decorum is, has been and will be maintained--that's why I wondered if these examples were some form of perfect tense.EDIT

How can I reliably and accurately identify the passive voice in writing or speech? I'm not interested in advice about whether or not to use it yet... I just want to know for sure what it is, so that I don't look as stupid as .


The gravitational waves are fact. They are produced in a way predicted 100 years before by Einstein. Anything with energy affecting stress tensor of space time produces them. What does it happen with moving photon losing its energy in a way creating gravitational waves? Eventually it will dissapear. So finally when all matter decays and becomes in form of energy respectivly photons and they decay becoming gravitational waves in the end we will finish with vibrating spacetime? Is that the case?

Due to the mass-energy equivalence, both matter and EM radiation bend spacetime, and both are capable of forming singularities (black hole, white hole/kugelblitz). In light of this, why do photons traveling from the most distant reaches of the observable universe not lose energy due to the gravitational radiation they must emit? Furthermore, mustn't cosmic rays (e.g. protons) slow down or stop as they lose energy through the same mechanism?


I'm trying to prove the first supplement of the quadratic reciprocity law in its particular form: $$-\bar{1} \text{is a square in} \mathbb{Z}/p\mathbb{Z} \iff p \equiv 1 \pmod 4$$ For the forward part, I'm thinking about applying Euler's criterion, since we know $-\bar{1}$ is a square. For the backward part, my starting point is that I have proved that $x^{p-1}=\bar{1}$ and that implies that: $$\Bigl(x^{\frac{p-1}{2}} - \bar{1} \Bigr)\Bigl(x^{\frac{p-1}{2}} + \bar{1} \Bigr) = \bar{0}$$

I came across this problem and I believe Lagrange's theorem is the key to its solution.  The question is:     Let $p$ be an odd prime. Prove that there is some integer $x$ such that $x^2 \equiv −1 \pmod p$ if and only if $p \equiv 1 \pmod 4$.   I appreciate any help.  Thanks.


I can't center horizontally a h6 (or any) tag inside a flex div. I think I've tried all approaches align-, justify-:self, items, content, but nothing works! I just want to place a div with 80% of its size and put text inside it, why is it supposed to be that hard?

I won't alignnnnnn

How can I horizontally center a
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Foo foo


I want to fill intersection of two (three) sets like this pictures, but I can't do that.     How can I do that?

How do I create a Venn Diagram with entities no larger than below, but with text scaled to fit; and circles in alignment horizontally?  \documentclass[a4paper, 14pt]{article}  \usepackage{tikz}  \begin{document}  \begin{tikzpicture}   \tikzset{venn circle/.style={draw,circle,minimum width=3cm,fill=#1,opacity=0.4}}    \node [venn circle] (A) at (0,0) {first order logic};   \node [venn circle] (B) at (30:2cm) {logic programming};   \node[below] at (barycentric cs:A=1/2,B=1/2){definite clause logic}; \end{tikzpicture}    \end{document}


I have a website where the number of visitors is increasing and it is facing a poor response time. I am not a server specialist and for this reason I want to expose my issue here to receive some feedback. The website has the following characteristics:   Developed with ASP.NET Web Forms (I will be implementing a new version with ASP.NET MVC soon). It uses a PostgreSQL 9.1 database. It is 100% dynamic which means that every page is formed at run-time getting information from the DB. Hosted in a cloud server with 2 Cores and 4 GB of RAM. Windows Server 2012 in drive C: PostgreSQL DB in another "hard disk" as drive D: The average number of daily visitors is 2,500   Watching the Task Manager I can notice that there are many PostgreSQL processes which consume CPU 100%. Another process that is shown in the "IIS Worker Process" but I have not seen it as critical as the PostgreSQL process. So it seems that the main issue here has to do with the database access. When CPU usage is high the website response is extremely low and also it is very difficult to establish a remote desktop connection.  I have thought about upgrading the cloud server to, for example, 4 cores and 8 GB of RAM, but firstly I want to get feedback from experts here so I can take the best approach. I am not a server expert and, for this reason, I do not want to take steps blindly.

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


What are the best and/or easiest methods for importing data from Excel (.xls) into an Oracle database?  Please, kindly clarify with any code examples you can.

I am looking for a free tool to load Excel data sheet into an Oracle database. I tried the Oracle SQL developer, but it keeps throwing a NullPointerException. Any ideas?


How to prove that epsilon-naught is countable without using Axiom of Choice?  or, Can we explicitly show that there is isomorpism between epsilon naught and subset of rational number?

I know that with choice, the countable union of countable sets is countable, making $\omega^\omega$ and $\epsilon_0$ both countable. Can we show this without choice? E.g. in the case that $\omega_1$ is a countable union of countable sets.


I'm studying the basics of quotient groups. I understand that if you build a quotient set from cosets of a group and the subgroup you are using to build them is normal then you end up with a group.  I fail to see why the fact that we can define operations in the quotient set and make it into a group is meaningful.  What is the motivation to do it? Either historical perspective, practical perspective or any other to understand why we care about this is welcome.

The basic concept of Quotient Group is often a confusing thing for me,I mean can any one tell the intuitive concept and the necessity of the Quotient group, I thought that it would be nice to ask as any basic undergraduate can learn the intuition seeing the question. My Question is :   Why is the name Quotient Group kept,normally in the case of division, let us take the example of $\large \frac{16}{4}$ the Quotient of the Division is '$4$' which means that there are four '$4$'s in $16$, I mean we can find only $4$ elements with value $4$     So how can we apply the same logic in the case of Quotient Groups,like consider the Group $A$ and normal subgroup $B$ of $A$, So if $A/B$ refers to "Quotient group", then does it mean:           Are we finding how many copies of $B$ are present in $A$??, like in the case of normal division, or is it something different ??       I understood the Notion of Cosets and Quotient Groups,b ut I want a different Perspective to add Color to the concept. Can anyone tell me the necessity and background for the invention of Quotient Groups?  Note: I tried my level best in formatting and typing with proper protocol,if in case, any errors still persist, I beg everyone to explain the reason of their downvote (if any), so that I can rectify myself, Thank you.


I was unable to visit Stack Exchange for around the past 48 hours (much to my consternation), so I got one of those emails telling me I have new inbox notifications.   The problem:    There are only 4 distinct items in the list, but 34 entries total (the link to  was repeated 15 times and the link to  was repeated 17 times).  If it matters, I'm a moderator on the site from which all these notifications originated.

So, I started getting all my Stack Exchange inbox items duplicated.    It started with this email, and every email since has done the same thing. Not 15 times, but several times.


I am totally new to UBUNTU (and dual CPUs).  Do I just download the current iso (14.04 LTS 64-bit) from www.ubuntu.com/download/server, or do I need something else to support a server using dual cpus?    I have a Dell PowerEdge R720 server with dual Intel Xeon E5-2637v2 4c 3.5GHz CPUs; with hardware based RAID (PERC H710P); iDRAC7 Express...  We have placed it on the rack and upgraded the BIOS.    I am after the usual LAMP system.

I am thinking of getting a dual Intel Xeon machine, each CPU is a quad core.  Will Ubuntu utilize both processors, especially with both being quad core, optimally?  Wanting to do Video editing and processing, but the Xeon machine's clock speed is actually slower than my current computer, so if both procs are not being used, I will actually end up with a slower machine than I already have.  I am not too familiar with dual processor machines. Thanks in advance for any answers.


I have seen people saying it is a bad use of grammar when someone says 'more perfect' or 'most perfect', since something that is perfect can't be better if you look at it literally.  However, we do use it in our daily communication or when we want to express ourselves in a more romantic way, be it because you are writing poetry or for some other reason.  In my case, I'm translating a text from German in which the word volkommener appears midway, and this word itself translates to "more perfect" or "more complete". As I am wishing to translate it literally, as "more perfect", I came across this doubt, should I write "more perfect", or "perfecter", ignoring the fact that, if something is already perfect, there's no room for improvement whatsoever.

Which one of these adjectives is correct? I can see that both of them are being used, I'm just not sure which one is grammatically correct. Are there any general rules to follow as to the use of one against the use of the other?


Consider $s\in\{0,\dots,n\}$. Let $X$ be the set of all the $s$-subsets of $[n]$. Also consider the action of $S_n$ on $X$ by $\sigma\cdot \{x_1,...,x_s\}=\{\sigma(x_1),...,\sigma(x_s)\}$. Let $x\in X$.  How can I find $| \operatorname{Stab}_{S_n}(x)$|?  I read the definition of stabilizers, but I don't have idea how to prove it. It seems a very basic theorem so I tried to find previous threads but without any success.

Show that the group $S_n$ (right) acts on the set of subsets of $\{1,2,\ldots n\}$ by $\rho(S,\sigma)=S\sigma$. Show that there are $n+1$ orbits, one for each possible value of $|S|$. Show that if $|S|=k$ then $\mathrm{Stab}(S)\cong S_k\times S_{n-k}$.  I have shown that there are n+1 orbits but now I am stuck with the last bit. my initial thought is that if I let $S =\{1,2,3,...,k\}$ then $\mathrm{Stab}(S)$ would involve $(1)(2)(3)...(k)$ i.e. mapping to itself and then $k+1$ to $n$ mapped in any ways ($S_{n-k}$) I feel like $\mathrm{Stab}$ is isomorphic to $S_{n-k}$ what am I misunderstanding here? How would I prove the last part? Thanks a lot


I've heard someone state that the double slit experiment can also be done with atoms, not just electrons or photons of light.

If we take the double slit experiment as a way of demonstrating the wave-particle duality, which types of particles would show an interference pattern?  For example, I know that electrons show such a pattern. But do protons, too? What about atoms? Where is the boundary between "wavey particles" and "classical particles"?


I am not sure how to show this. It seems obvious but maybe its not. The help would be greatly appreciated!

Possible Duplicate:             If $F_n$ is an increasing sequence of sigma fields then $F = \bigcup_{n=1}^\infty F_n$ is a field. Please help me find a counter-example to show that $F$ may not be a sigma-field.