Okay, so I'm currently working on a Computer Science project and I'm coming across an error. Whenever I run these two classes, I get an error where it doesn't read the input and just does nothing after my Scanner gives it a value. I'd appreciate some clarification on what I'm doing wrong. Thanks.   public Recipe(String Directions, String RecipeName, int CalorieCount, MethodOfCook H){      directions = Directions;      recipeName = RecipeName;      calorieCount = CalorieCount;      hi = H;  }  public static void RecipeDisplay(){     for(int i = 0; i <= Ingred.size(); i++){         if (Ingred != null){             Recipe.DisplayHelper();             System.out.println("===============================");             System.out.println(recipeName);             System.out.println("===============================");             System.out.println("Directions; " + directions);             System.out.println("Calories; " + calorieCount);             System.out.println("Cooking Method; " + hi );         }     } }  public static void DisplayHelper(){     int index = 0;     System.out.println("Would you like to add a recipe?(Type YES or NO)");     Scanner wantTo = new Scanner(System.in);     String bad = wantTo.nextLine();      if(bad == "YES"){         index++;         System.out.println("First we'll start with Ingrediants, Input as many as you like");         Recipe.addIngrediants();         Recipe.editIngrediants();         Recipe.removeIngrediants();          System.out.println("Great, now lets name your Recipe;");         Scanner nameDude = new Scanner(System.in);         String yesName = nameDude.nextLine();         yesName = recipeName;          System.out.println("Moving on, Input your Directions;");         Scanner inputDude = new Scanner(System.in);         String bud = inputDude.nextLine();         bud = directions;          System.out.println("Now input a Calorie Count (Numbers Only!)");         Scanner numberMan = new Scanner(System.in);         int jman = numberMan.nextInt();         jman = calorieCount;          System.out.println("Now select an Enum Method;");         System.out.println("Remember your values are;");         Scanner sc = new Scanner(System.in);         MethodOfCook bu = hi;         for (MethodOfCook bum : bu.values())             System.out.println(bum);          // read strings from Scanner - display Algorithm value or   throw exception         while(true){             try             {                 System.out.print ("Enter value  ");                 System.out.println("Great, your value is" + bu.valueOf(sc.next()));                 Recipe ji = new Recipe(bud, yesName, jman, bu);                 System.out.println(ji);             }             catch (IllegalArgumentException m){                 System.out.println("  Error: " + m);             }             }      }      else{         System.out.println("Okay thanks.");      } }   The error is mainly in my DisplayHelper I believe, also I'm trying to link the scanner inputs to my recipe class, so that I can build an ArrayList of recipes in a separate class, thanks in advance! (Sorry for the strange format, it doesn't seem t want to work.)

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


Where should I ask questions about using software? For example:  How do I convert a .gif picture into a .png picture using XYZ software? How do you change the window; workspace layout in XYZ software? How do you import a document from ABC software into XYZ software? Where is the "Save" button in XYZ software?   I know I can't use , as it's not relating to programming, and I can't use  as it is not relating to the installation of software or anything to do with hardware.  To be specific, I'm looking for help on using , both in the departments of making scripts and basic usage/techniques.    Yes, I know I can ask script-related questions on , but where do I ask questions about usage of the software?

There seems to be more than a few computer science/programming Stack Exchange networks (is that the correct term?). Stack Overflow, being the first, has by far the most users, questions, and answers.  What is the reasoning for creating the others, and are there clear guidelines for which kinds of questions should be posted? I can see a large amount of potential overflow, many cases of people not getting a good answer to their question, because the person who has the answer isn't browsing that particular network at the moment.  I understand that they were probably created for organizational purposes, but wouldn't it almost make more sense to just have them as categories under Stack Overflow, keep them separated but still connected, instead of making people have to create multiple 'account's, one for each network?  I am sure there was a very good reason to break them up, but as someone that is new to SE, it can be somewhat intimidating to decide which one to post in to ensure you get a good answer. For example, if I am a computer science student, my first instinct might to be to post in the computer science network, until I see that it literally has 1% of the users as the Stack Overflow network, which still seems to be for programming/computer science related questions.  So my second instinct would then to be to post it into the Stack Overflow site on the basis that I have a significantly higher chance of my question being seen and getting a good answer. Then I notice that there is also a 'programmers' network, and I don't even begin to know where that fits in. I, and I am assuming most people, will probably just post on Stack Overflow to be safe.  My question is, other than the short little description blurb of each one, is there a clear cut set of guidelines which what each network is intended for, what kinds of questions should go to each one, and is anything being done to encourage people to post in these newer, smaller (more specialized?) networks as opposed to just posting in big daddy Stack Overflow?  Now again, this is for computer science/programming/"why isn't this code doing what I want?" related questions, I am not saying that if I had a question about Linux or WordPress or something I would have the same confusion.


Though I see that many have asked the question of whether acronyms that ends with a "s" should be s' or s's, I have puzzled over whether nouns that ends in “s” should end in s's or s'.  Many sources online and in SAT books disagree with each other and I am confused because of all the disagreements.  If given the example:      Louis’s scarf   Louis’ scarf    One book stated that it was Louis's while another said that it should be Louis'.  I specifically looked for the answer what College Board's SAT would agree with and I would also like to know warrants to the answer as well.

Many questions already ask about this topic ( , , etc.) and their answers vary, but they always give exceptions to the apostrophe-s rule, for example:      6.24 The general rule for the possessive of nouns covers most proper nouns, including most names ending in sibilants."   Examples they give include Kansas’s, Ross’s land, and Jones’s reputation. Exceptions include Jesus’  and Moses’.  Which names does this apply to?  Is the Aeneas’  form correct, or is it Aeneas’s instead?


For my assignment, I was required to make a const static double variable in a class but my compiler gives an error.       const static double long_tarif = 1500.0;//error const static int long_tarif = 1500;//no error  IntelliSense: a member of type "const double" cannot have an in-class  initializer   I'm working on visual studio 2013.

I noticed C++ will not compile the following:  class No_Good {   static double const d = 1.0; };   However it will happily allow a variation where the double is changed to an int, unsigned, or any integral type:  class Happy_Times {   static unsigned const u = 1; };   My solution was to alter it to read:  class Now_Good {   static double d() { return 1.0; } };   and figure that the compiler will be smart enough to inline where necessary... but it left me curious.  Why would the C++ designer(s) allow me to static const an int or unsigned, but not a double?  Edit: I am using visual studio 7.1 (.net 2003) on Windows XP.  Edit2:  Question has been answered, but for completion, the error I was seeing:  error C2864: 'd' : only const static integral data members can be initialized inside a class or struct


Context  I run a three screen setup and it takes forever to get from side to side when using the trackpad even when set to max in settings. I'm looking for (and thought I had found) a solution that will allow me to set the trackpad tracking speed as arbitrarily high as I want.  What I've Done So Far  I've already tried the solution laid out . The problem is that no matter how high I set the number when running defaults write -g com.apple.trackpad.scaling x the sensitivity still isn't high enough for me.  At first I thought this might mean that there is another limit imposed besides the one dictated by the GUI. Proceeding on this hypothesis (and the assumption that if Apple throttled the trackpad they would do the same to the mouse) I ran defaults write -g com.apple.mouse.scaling 1000 (note the 'mouse' instead of 'trackpad').  Result: My mouse is now so sensitive that if my cursor happens to land where I intend I can only ascribe it to the will of God.  Remaining Problem  No matter how high I set the number for the trackpad, one motion across its surface isn't enough to get from the left edge of my first monitor to the right edge of my third. Note: The goal here is not to set the trackpad speed and mouse speed separately (as in the question marked as duplicate). I simply wanted to indicate that the analogous steps that work for a mouse do not work for a trackpad. In addition, the selected answer in the duplicate provides a dead link (so not much help).   The goal is to be able to set the trackpad speed significantly faster than allowed by the GUI in settings. I'm open to downloading a third party tool, but would prefer a command line solution (or explanation as to why the one I've tried doesn't work as expected).  I realize this is probably a pretty niche question, but your help is much appreciated.

Is there any way to set different tracking speed for Magic Mouse and for built-in trackpad?  I'm using both, but Magic Mouse acts good for me at max tracking speed, but trackpad good for me at average tracking speed.   I see that tracking speeds are adjusted separately for each input device, but actually they affect both mouse and trackpad.   Is there any chance to set different configurations?  MacOs Sierra 10.12.2


I have little or no working knowledge of Latex. I have .tex file for a journal paper submission in which references in the article are mentioned like \cite{JinGaherty2015}. At the end of the main text, there is a line \bibliography{aktomo_new}. The separate file aktomo_new.bib has the definition of the references, for example @article{JinGaherty2015,      AUTHOR = {G. Jin and J. B. Gaherty},      TITLE = {{Surface wave phase-velocity tomography based on multichannel cross-correlation}},      JOURNAL = {\gji},      PAGES = {1383-1398},      VOLUME = {201},      NUMBER = {3},      DOI = {10.1093/gji/ggv079},      YEAR = {2015} }  However the journal requires one final file for submission. Simply copy-pasting the above lines from aktomo_new.bib to the main .tex file is not working. Someone showed me a working .tex file that has references written as \bibitem[\protect\citeauthoryear{Berg, Lin, Allam, Schulte-Pelkum, Ward, and   Shen}{Berg \textit{et~al}.}{2020}]{Berg2020} Berg, E.~M., F.-C. Lin, A.~Allam, V.~Schulte-Pelkum, K.~M. Ward, and W.~Shen   (2020). \newblock {Shear velocity model of Alaska via joint inversion of Rayleigh wave   ellipticity, phase velocities, and receiver functions across the Alaska   Transportable Array}. \newblock {\em \jgrse\/}~{\em 125}, doi: 10.1029/2019JB018582.  It makes no sense for me to re-write all references from the first format to the second format so that I can have one final file. Any suggestions ?

Overleaf V2 does not seem to have a way to get the BBL file for arxiv, how do I get it?


I was playing singleplayer vanilla 1.14, and I went to a spawner near my house to grind out some XP. When I went back to my house, most of it was missing. Most of the doors, wood, and stone blocks had just disappeared. It wasn't a clear cut like when loading a chunk goes wrong. Some of the blocks of the base and the roof were still there, but most of the second floor was gone. Things like beds, furnaces, and stuff like that, were still there floating in the air.  I'm not sure if this information helps, but the dogs from the house ran to me while I was at the spawner.  Does anyone know how this is possible?

I have been doing a new survival world, and I was out on a completely different island exploring, but when I came back to my house, I was greeted by this.  My first thought was creepers, but I then realized that only my dark wood blocks disappeared and nothing else. All of my windows were intact, and so were my anvil, crafting table, and all of my chests. Then I thought an enderman stole blocks, but just look at how many blocks are missing.  What happened here, and why have only the dark oak blocks disappeared?


I'm trying to find all integers $n$ such that $n+2$ is a cube and $n-2$ is a square.   I already know that only 6 and 123 are solutions but not know how to show it. I tried to use the proof of 26 being the only one such that $n+1$ is a cube and $n-1$ is a square but I'm having troubles doing it as in $\mathbb{Z}[i]$ I don't know how to conclude that if $y^3=x^2+4=(x+2i)(x-2i)$ then both $x+2i$ and $x-2i$ are cubes (It is at least true?).  Thank you very much.

Find all integer solutions to $x^2+4=y^3$.  Some obvious solutions are $(x,y)=(\pm2,2)$. Are these the only ones?


Are mathematical notions like closed sets, limits of sequences, measures, and function spaces basically irrelevant in the day to day work of a physicist? Naturally, such concepts are the foundations upon which everything stands in both mathematics and physics, but do physicists need to concern themselves with the fine details of these concepts in their daily work or can they 'get away with' not having to use them while performing research?  Particularly in the areas of solid state physics, quantum mechanics, relativity, optics, and electromagnetism. Do any/some/all of these fields regularly/sometimes/never have to go that level of mathematical rigour? If these concepts do get used regularly in some particular fields, it would be great to hear some examples of how they arise and why they are necessary.

The purpose of this question is to ask about the role of mathematical rigor in physics. In order to formulate a question that can be answered, and not just discussed, I divided this large issue into five specific questions.  Update February, 12, 2018: Since the question was put yesterday on hold as too board, I ask future to refer only to questions one and two listed below. I will ask a separate questions on item 3 and 4. Any information on question 5 can be added as a remark.         What are the most important and the oldest insights (notions, results) from physics that are still lacking rigorous mathematical   formulation/proofs.   The endeavor of rigorous mathematical explanations, formulations, and proofs for notions and results from physics is mainly taken by   mathematicians. What are examples that this endeavor was beneficial to   physics itself.       What are examples that insisting on rigour delayed progress in physics. What are examples that solid mathematical understanding of certain issues from physics came from further developments in physics itself. (In particular, I am interested in cases where mathematical rigorous understanding of issues from classical mechanics required quantum mechanics, and also in cases where progress in physics was crucial to rigorous mathematical solutions of questions in mathematics not originated in physics.) The role of rigor is intensely discussed in popular books and blogs. Please supply references (or better annotated references) to academic studies of the role of mathematical rigour in modern physics.   (Of course, I will be also thankful to answers which elaborate on a single item related to a single question out of these five questions. See update)  Related Math Overflow questions:     (related to question 1);  ;  .


I have the following method that runs on beforeUpdate and beforeInsert Triggers on Event:  private void populateMeetingStatus() {     System.debug('populateMeetingStatus');     for (Event event_i : (List <Event>) Trigger.new)     {         if(event_i.Event_Details__C != null)         {             if(event_i.Meeting_Status__c == 'Completed')             {                 //"Event Locked" - The field should be True if Meeting status is Completed                 System.debug('event_i.Event_Details__c:' + event_i.Event_Details__c);                 System.debug('event_i.Event_Details__r.Event_Locked__c:' + event_i.Event_Details__r.Event_Locked__c);                  event_i.Event_Details__r.Event_Locked__c = true;              }             else             {                 //"Event Locked" - The field should be false                 event_i.Event_Details__r.Event_Locked__c = false;             }         }     }   it fails on the line   event_i.Event_Details__r.Event_Locked__c = true;   with the error     System.NullPointerException: Attempt to de-reference a null object   i printed the value of this field:  10:22:49:172 USER_DEBUG [1512]|DEBUG|event_i.Event_Details__c:a1G9E000000InGTUA0 10:22:49:172 USER_DEBUG [1513]|DEBUG|event_i.Event_Details__r.Event_Locked__c:false   this fiels exists, and still i receive this error. why does this occur? how can i solve it?

I have a lookup to a custom object called Project on my Opportunity object. I am trying to write a trigger that updates an Active, Awarded, and Title on the Project object whenever the Active, Awarded, or Title field is updated on Opportunity based some on more logic that isn't in my code below. This is my first trigger and needing a little help due to a NullPointerException where I try to set Project__r.Active__c = true. Any thoughts?      trigger ProjectFieldsTrigger on Opportunity (before insert, before update) {       //List<Opportunity> opp = [SELECT Name, Active__c, Funded__c, Title__c, Project__r.Name, Project__r.Active__c, Project__r.Awarded__c      //  FROM Opportunity WHERE Id IN :Trigger.New];      for(Opportunity o: Trigger.New){          if(o.Project__c != null){              if(o.Active__c == 'Y'){                 o.Project__r.Active__c = true;             }      }  }


Consider the below code  import java.util.HashSet; import java.util.Random; import java.util.Set;   public class Test {  /**  * @param args  */ public static void main(String[] args) {     // TODO Auto-generated method stub      Person p1= new Person();     //Person p2= new Person();     p1.setName("same1");     //p2.setName("same2");     Person p2=p1;     Set<Person> set= new HashSet<Person>();     set.add(p1);     set.add(p2);     for(Person p: set){         System.out.println(set.size()+">>"+p.getName()+" hashcode "+p.hashCode());     }   }  }  class Person{ private String name;  public String getName() {     return name; }  public void setName(String name) {     this.name = name; }  @Override public boolean equals(Object obj){     return true;  }  @Override   public int hashCode() {     Random ran = new Random();     int x = ran.nextInt(6) + 5;     System.out.println("in hahcode method"+x);     return x;   } }   As set does not contain duplicate, Here I have return true from equals method and return different hashcode for the same object. HashSet treat them as unique object. So far so good, as HashSet internally use HashMap to store objects.   It appears from above code snippet that HashSet use hashCode to check uniqueness not equals method. If hashCode is different for two objects,they will be stored in HashSet whether they are equal or not? Please let me know if I am missing something.

What issues / pitfalls must be considered when overriding equals and hashCode?


What is the most modern (best) way of satisfying the following in C#?  string encryptedString = SomeStaticClass.Encrypt(sourceString);  string decryptedString = SomeStaticClass.Decrypt(encryptedString);   BUT with a minimum of fuss involving salts, keys, mucking about with byte[], etc.  Been Googling and confused at what I'm finding (you can see the list of similar SO Qs to see this is a deceptive question to ask).

How can I encrypt and decrypt a string in C#?


\documentclass[11pt]{article}    \usepackage{geometry}                        \geometry{a4paper}    \usepackage{mathpazo}  \usepackage{amsmath} \usepackage{amssymb} \usepackage{booktabs} \usepackage{tabularx}  \begin{document}  \begin{table}[htdp]  \centering \caption{Absorbances of samples of different Concentrations\label{mytable}} \begin{tabular}{lll}  \toprule Sample & Concentration \linebreak (mg/L) & Absorbance at \linebreak $\lambda_{max}$ \\  \midrule blank  & 0.0000   & 0.000 \\                                                                    a      & 0.2849   & 0.059 \\                                                                    b      & 0.7122   & 0.160 \\                                                                 c      & 1.424    & 0.311 \\                                                                 d      & 2.137    & 0.468 \\                                                                   e      & 2.849    & 0.608 \\  \bottomrule \end{tabular} \end{table}  \end{document}     Why don't my \linebreaks work?  EDIT: I tried to change the code to a two column table  \documentclass[11pt]{article}   \newcommand{\specialcell}[2][c]{\begin{tabular}[#1]{@{}c@{}}#2\end{tabular}}  \usepackage{siunitx} \usepackage{amsmath} \usepackage{booktabs}  \begin{document} \begin{table}            \centering     \caption{Absorbances of 20 \si{\ml} sample at different Wavelengths}     \label{mytable}     \begin{tabular}{lS[table-format=1.3]}          \toprule         {\specialcell[t]{Wavelength \\in \si{\nano\meter}}}  & Absorbance   \\          \midrule         400      & 0.240  \\                                                                            425      & 0.382  \\                                                                            450       & 0.486  \\                                                                         475      & 0.574  \\                                                                         500      & 0.608  \\                                                                           505      & 0.608 \\         510      & 0.602 \\          525      & 0.508 \\         \bottomrule     \end{tabular} \end{table}  \end{document}       But it throws and error when I add an 'e' to Absorbance

I have some text in a table and I want to add a forced line break. I want to insert a forced line break without having to specify the column width, i.e. something like the following: \begin{tabular}{|c|c|c|} \hline Foo bar & Foo <forced line break here> bar & Foo bar \\ \hline \end{tabular}  I know that \\ inserts a line break in most cases, but here it starts a new table row instead.  A similar question was asked before:


How does one prove probability integral transform? So when $Y = F_X(X)$ where $X$ has a continuous distribution for which the cumulative distribution function is $F_X$, why does $Y$ have a uniform distribution? And what would Y's relationship with $\text{uniform}(0,1)$ distribution?

This theorem seems to hold great potential for an intuitive explanation, yet I'm still struggling for it.  Basically, it is saying that if $y = F(x)$, then y would have distribution $Unif[0,1]$. Intuitively, why?  Many thanks!


I've recently started doing the Dragonborn quests in Skyrim, but after the quest 'Temple of Miraak', Miraak steals my dragon souls. Is there any way to stop this apart from killing him?

After reading the book Waking Dreams and seeing Miraak, I couldn't absorb a dragon's soul. I killed more than 10 dragons and Miraak took all the souls. Is this supposed to happen?


I've noticed that people from the Washington, Oregon area tend to omit "to be" when describing something that needs to be completed.  For example, just today one of my consulting engineers sent me an update on a construction project wherein he stated, "The raw water line still needs tested."  He did not make a typo.  Is this just a grammatical form used by folks in this area?

In the  (and possibly elsewhere), the following construction is possible:        This car needs washed. (=needs to be washed)   The room needs cleaned. (=needs to be cleaned)      It appears that, if a verb like needs is followed by a passive construction in the infinitive, the "to be" portion is left out.  This construction sounds so unnatural to my ear that I have no intuition as to the extent to which it can be extended to other words and contexts.  If anyone here is a native speaker of this dialect of English, perhaps they can help to explain the limits on its use.  My basic question is: how productive is this particular construction among those who use it?  To be more specific, can this construction be used with any verb (if that verb can be immediately followed by a passive construction, of course)?  That is, would (any of) the following be acceptable, for example?        At this restaurant, we always wait seated. (=wait to be seated)   My kid hates picked last in sports. (=hates to be picked)   We all want loved. (=want to be loved)      If this construction is restricted, then which verbs can be used, aside from need?  Edit: What I am really hoping for here is that there is someone who happens across this question that can say, "I actively use this construction, and here's what I can and can't say."


I saw this question somewhere and made me think do 3x4 matrices have an inverse, as I previously that that only square matrices have an inverse.  If non-square matrices have an inverse, especially if 3x4 has one please let me know, the reason why.  Thanks!

I know that only square matrices can have inverses. Nevertheless, assume that we have an $n \times k$ matrix $A $ with $n\neq k$. Then it may still be possible to construct a matrix $B$ such that  $$BA=I$$  For example, assume that $B=(A^TA)^{-1}A^T$, then $BA=(A^TA)^{-1}(A^TA)=I$  I know that $B$ cannot be called an inverse, due to the definition of inverse requiring $A$ to be a square matrix. Nevertheless, it is sort of like an inverse, so do we have a name/theory about these kinds of "inverses"?


I've been trying to install the latest version of Node.js, but my terminal is throwing this error when I try to install. Any tips on how to resolve this would be much appreciated. thanks E: Malformed entry 1 in list file /etc/apt/sources.list.d/nodesource.list (Component)

I'm relatively new to Ubuntu 16.04, and everything has been going fine until my OS threw this error today.   Below is the source code from /etc/apt/sources.list for line 54:  deb http://archive.canonical.com/ partner   I have tried appending ubuntu after the / and before partner, but this does not seem to work.   Any ideas what else to try? I can't run sudo apt-get update until this is fixed.


Two natural numbers $x$ and $y$ are selected at random. Find the probability that $x^2 + y^2$ is divisible by $10$.  I have no clue how to do this.

Given two random integers $a$, $b$ calculate probability of $a^2$ + $b^2$ is divisible by $10$.  I've tried to simulate this process and got a result about $0.18$ (maybe incorrect), but have no idea why.


When I try to download an app using the terminal or store I get an error that says I have no free disk space. My laptop has 4gb of ram and aroun 900gb free hdd space.I can even see it in gparted under /home. Any way to solve this.               total        used        free      shared  buff/cache   available Mem:           3784        1780         720         171        1283        1572 Swap:          9999         232        9767   Filesystem     1M-blocks  Used Available Use% Mounted on udev                1861     0      1861   0% /dev tmpfs                379     2       378   1% /run /dev/sda2           9779  9297         0 100% / tmpfs               1893    41      1852   3% /dev/shm tmpfs                  5     1         5   1% /run/lock tmpfs               1893     0      1893   0% /sys/fs/cgroup /dev/loop1           518   518         0 100% /snap/intellij-idea-community/143 /dev/loop2            90    90         0 100% /snap/core/6818 /dev/sda1           4991     7      4984   1% /boot/efi /dev/sda4         913263 28995    837809   4% /home tmpfs                379     1       379   1% /run/user/1000 /dev/loop3            36    36         0 100% /snap/gtk-common-themes/1198 /dev/loop4            66    66         0 100% /snap/discord/93 /dev/loop5           141   141         0 100% /snap/gnome-3-26-1604/82

My first issue was when I tried to apt-get update or apt-get upgrade. On upgrade I get the following error:  You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: linux-image-server : Depends: linux-image-3.2.0-27-generic but it is not installed E: Unmet dependencies. Try using -f.   I tried running apt-get install -f and this was the output(after saying yes on prompt)  (Reading database ... 186183 files and directories currently installed.) Unpacking linux-image-3.2.0-27-generic (from .../linux-image-3.2.0-27-generic_3.2.0-27.43_amd64.deb) ... Done. dpkg: error processing /var/cache/apt/archives/linux-image-3.2.0-27-generic_3.2.0-27.43_amd64.deb (--unpack):  failed in write on buffer copy for backend dpkg-deb during `./boot/System.map-3.2.0-27-generic': No space left on device  No apport report written because the error message indicates a disk full error                                                                           dpkg-deb:    error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.2.0-27-generic   /boot/vmlinuz-3.2.0-27-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.2.0-27-generic /boot/vmlinuz-3.2.0-27-generic Errors were encountered while processing: /var/cache/apt/archives/linux-image-3.2.0-27-generic_3.2.0-27.43_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   I tried running apt-get autoremove and it gives me the same error as apt-get upgrade.  When I run df, I get this for /boot:  /dev/sda1                    233191     230297         0 100% /boot   So, I read elsewhere that I should try to purge old kernels. I checked for what kernels I had with:  $ dpkg -l linux-image-\* | grep ^ii ii  linux-image-2.6.38-13-server  2.6.38-13.52  Linux kernel image for version 2.6.38 on x86_64 ii  linux-image-3.0.0-13-server   3.0.0-13.22   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-14-server   3.0.0-14.23   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-15-server   3.0.0-15.26   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-16-server   3.0.0-16.29   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.0.0-17-server   3.0.0-17.30   Linux kernel image for version 3.0.0  on x86_64 ii  linux-image-3.2.0-24-generic  3.2.0-24.39   Linux kernel image for version 3.2.0  on 64 bit x86 SMP ii  linux-image-3.2.0-25-generic  3.2.0-25.40   Linux kernel image for version 3.2.0  on 64 bit x86 SMP ii  linux-image-3.2.0-26-generic  3.2.0-26.41   Linux kernel image for version 3.2.0  on 64 bit x86 SMP   When I try to remove the oldest with this:  $ sudo apt-get purge linux-image-2.6.38-13-server Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: linux-image-server : Depends: linux-image-3.2.0-27-generic but it is not going to be     installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).   How can I free up or extend boot without messing up my installation?


Say you have one file called foo.pdf. How can I find out whether my machine contains another file, say bar.pdf, that has the exact same content but just a different name?

Is it possible to find duplicate files on my disk which are bit to bit identical but have different file-names?


I'm attempting to get a JTextArea to display the output from a COM Port as a string. However, the code i'm using to tell the JTextArea what it should be displaying is producing NullPointerExceptions. I know what's causing the error roughly but i'm just looking for the best way to deal with the issue to prevent it happening. The code for the text areas is:      if (Serial.currPortId == null) {         listenState.setText("NONE");     } else {         listenState.setText(Serial.currPortId.getName().toString());     }     if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[0].toString())) {         tab1sheet.setText(serialImport.datafeed); }     else {         tab1sheet.setText("N/A");     }     if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[1].toString())) {         tab2sheet.setText(serialImport.datafeed); }     else {         tab2sheet.setText("N/A");     }     if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[2].toString())) {         tab3sheet.setText(serialImport.datafeed); }     else {         tab3sheet.setText("N/A");     }   The errors are occurring at the start of   if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[0].toString())) {     tab1sheet.setText(serialImport.datafeed); }   and I assume the if statements for the other two aren't working either.  I'm also providing the code for the serialports. It is as follows:  public void initialize() {     CommPortIdentifier portId = null;     Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();      while (portEnum.hasMoreElements()) {         CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();         for (String portName : PORT_NAMES) {             if (currPortId.getName().equals(portName)) {                 portId = currPortId;                 break;             }         }     }     if (portId == null) {         System.out.println("Could not find COM port.");         return;     }      try {         serialPort = (SerialPort) portId.open(this.getClass().getName(),                 TIME_OUT);         serialPort.setSerialPortParams(DATA_RATE,                 SerialPort.DATABITS_8,                 SerialPort.STOPBITS_1,                 SerialPort.PARITY_NONE);          // open the streams         input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));         output = serialPort.getOutputStream();         String datafeed = "";         datafeed.concat(input.toString());         serialPort.addEventListener(this);         serialPort.notifyOnDataAvailable(true);     } catch (Exception e) {         System.err.println(e.toString());     } }   I've attempted to change the code and nest it but it's still not working. It's now:  if (Serial.currPortId.getName() != null) {         if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[0].toString())) {             tab1sheet.setText(serialImport.datafeed); }         else if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[1].toString())) {             tab2sheet.setText(serialImport.datafeed); }         else if (Serial.currPortId.getName().toString().equals(Serial.PORT_NAMES[2].toString())) {             tab3sheet.setText(serialImport.datafeed); }         else {tab1sheet.setText("N/A");               tab2sheet.setText("N/A");               tab3sheet.setText("N/A");}     }

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 quite new to Stack Overflow and I want to help others by answering their questions. Of course, I want to search for questions that I could answer and 'tag' seems to be a good way. However, I cannot find how to filter questions based on multiple tags. The only thing I find is only to select one tag. As I learn rather widely but not deeply, I need to search multiple times in order to find a questions that i could contribute.   Is there a way to have a set of tags such that questions have either one of these tag will appear?   For example, for me, I would want to look into questions with tags (C/C++/Python/Linux/Objective-C/Android/iOS ... )

I'd like to be able to search for questions by multiple tags; for example "questions tagged 'nhibernate' and 'web-services'".  I can get close by searching for "nhibernate web-services" but the results tend to be a few questions that relate to both terms--but much more largely just questions that relate to one or the other.


I am just a doing a little project on my own, trying to create a bingo game. I'm wondering why I'm getting a nullpointer when trying to set the text of a JLabel. The only thing the JLabel needs to display is a random number 1-15.  static JLabel[] boardNumbers = new JLabel[25]; static Random r = new Random();   public static void generateBoard() {      for (int i = 0; i < 1; i++) {         if (i < 5) {             int n = r.nextInt(15);             numbersUsed[i] = n;             boardNumbers[i].setText("" + n);         } else if (i >= 5 && i < 10) {             //i numbers         } else if (i >= 10 && i < 15) {             //n numbers         } else if (i >= 15 && i < 20) {             //g numbers         } else {             //o numbers         }     }  }   The line that is giving me a nullpointer is this line boardNumbers[i].setText("" + n);  For the full source code you can view this:


PROBLEM     Let $H$ and $K$ be subgroups of a group $G$.  Prove that $HK = \{ab | a \in H, b \in K\}$ is a subgroup of $G$ if and only if $HK = KH$.   WHAT I KNOW  (1) If $H = \{e, \alpha, \alpha^2\}$ and $K = \{e, \beta, \beta^2\}$ are subgroups of $S_4$, one can show that $HK \neq KH$.  We can compute $HK$ and $KH$ to verify that:  In general, the product of two subgroups of a group $G$ is not a subgroup of $G$.  (2) If $H = \{h_1, h_2, \ldots, h_r\}$ and $K = \{b_1, b_2, \ldots, b_p\}$ are subgroups and one of $H$ or $K$ is normal in $G$, then (a) $HK = KH$, and (b) $HK$ is a subgroup of $G$.  (3) If $H$ and $K$ are normal subgroups of $G$, so also is $HK$.  QUESTION     How do I then solve the problem at hand, given that what I know seems to require that at least one of $H$ or $K$ is normal in $G$?  That is, how does one prove the statement in the PROBLEM section in full generality (without requiring that one of $H$ or $K$ is normal in $G$)?

Let $H$ and $K$ be subgroups of a group $G$, and let $HK=\{hk: h \in H, k \in K\}$, $KH=\{kh: k \in K, h \in H\}$. How can we prove that $HK$ is a subgroup iff $HK=KH$?


The first time I open Google Chrome after login, it takes ages to load. When it finally loads I can close it out and it opens normally. What could be causing this, and how can I fix it?

Since a few days ago my Gnome-keyring daemon hasn't been starting up properly.  After logging in:  ps aux | grep keyring user       3496  0.0  0.0 214408 15800 ?        SLl  13:30   0:00 /usr/bin/gnome-keyring-daemon --daemonize --login   Apps complain about not being able to access the keyring (and fail to do so), some shortcuts are very slow CTRL+ALT+T for terminal or Print screen can both take up to a minute between key press and action)  Seahorse does not show the login keyring  $ /usr/bin/gnome-keyring-daemon SSH_AUTH_SOCK=/run/user/1000/keyring/ssh $ ps aux | grep keyr user       3496  0.0  0.0 214408 15800 ?        SLl  13:30   0:00 /usr/bin/gnome-keyring-daemon --daemonize --login user       8524  0.1  0.0 211004 12468 pts/5    SLl  13:38   0:00 /usr/bin/gnome-keyring-daemon   Then, as soon as an app wants to access I get the keyring password prompt. Once unlocked, the keyring works properly.  I had a look to startup apps for my session and I only have one command that is relevant:  /usr/bin/gnome-keyring-daemon --start --components=ssh   I added /usr/bin/gnome-keyring-daemon to startup apps, but it will prompt for the keyring password after each login, which wasn't happening before.  Any idea on what happened and how to fix this please?


public static void main(String[] args) {             int[]array={1,55,37,86,84,99,3567,357,478,537,34};             System.out.println(findMaxMin(array));   //why is this not returning the numbers? it is just returning [I@48cf768c. i want it to return 3567 and 1.          }         public static int[] findMaxMin(int[]answer){             int max = answer[0];             for (int i = 0; i < answer.length; i++) {                 if (answer[i]>max){                    max=answer[i];                  }             }             int min = answer[0];             for (int i = 0; i < answer.length; i++) {                 if (answer[i]<min){                    min=answer[i];                  }             }              int[]array={max,min};             return (array);    //the return is the address not the actual numbers         }

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]


How to reduce the file size of each photo inside the folder. We want to keep the image dimension size of the photos and only reduce its file size.

this is my first post so I hope you'll be kind enough to forgive me if I make some formatting mistakes or else. This is one question I've had for quite some time and while looking for answers I have more questions arising. I was trying to find a way to compress pictures in a folder using convert in one command.  First I simply tried:  convert * -resize 50% Pic.jpg   However this returned the compressed pictures named Pic-0.jpg, Pic-1.jpg, etc. (I also tried $(find ".JPG") instead of * but this is expanded to the same. In order to have the formatting I wanted I tried:  convert * -resize 50% Pic_lorez_{1..3}.jpg   But this seemed to take the Pic_lorez_2.jpg and Pic3_lorez_3.jpg as input files, not output files. So following the advice of a friend, I tried:  find . -name "*.JPG" -exec convert {} -resize 50% {} \;   This compress all files under the same name but doesn't allow to put the name I want to these files (for example, Pic_lorez_{1,2,3,4,5,..100}.jpg).  Would xargs make it possible? Something along the lines of:  find . -name "*.JPG" | xargs convert ???   I couldn't figure out the proper syntax with xargs. I finally tried a direct pipe of find into convert but convert didn't seem to be able to work that way.


Yes I realize there are tons of material on the subject no I did not read them all. Now I have gone through good few of the answers and it got me as far as system finding the drivers on its own and trying to install them through Software and updates / additional drivers section. Problem is it starts download but than even if left for 15 hours it just doesn't download them once you click apply changes it just sits there on about 5% mark. Have any of you linux magicians can come up with idiot proof solution for complete ignorant like my self had linux for 24h.   lspci -knn | grep Net -A2     DeviceName: Realtek Gigabit Network Connection     Subsystem: Hewlett-Packard Company Device [103c:3660]     Kernel driver in use: r8169 02:00.0 Network controller [0280]: Broadcom Corporation BCM4312 802.11b/g LP-PHY [14e4:4315] (rev 01)     Subsystem: Hewlett-Packard Company Device [103c:365e]     Kernel driver in use: b43-pci-bridge

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


$$\lim_{n \to \infty} \frac{n!}{n^{n}}$$    Attempt:  $$n!=n\left( n-1 \right)\left( n-2 \right)...\left( n-\left( n-1 \right) \right)=n^{n}+...$$  $$\lim_{n \to \infty} \frac{n!}{n^{n}}=\lim_{n \to \infty} \frac{n^{n}+...}{n^{n}}=\lim_{n \to \infty} \frac{1+...}{1}=1+\lim_{n \to \infty} \ ...=1$$    I based this on the fact that $n$ is the highest power. The answer's meant to be $0$ though.

I am trying to check whether or not the sequence $$a_{n} =\left\{\frac{n^n}{n!}\right\}_{n=1}^{\infty}$$ is bounded, convergent and ultimately monotonic (there exists an $N$ such that for all $n\geq N$ the sequence is monotonically increasing or decreasing). However, I'm having a lot of trouble finding a solution that sufficiently satisfies me.  My best argument so far is as follows,  $$a_{n} = \frac{n\cdot n\cdot n\cdot \ldots\cdot n}{n(n-1)(n-2)(n-3)\dots(2)(1)} = \frac{n}{n}\cdot \frac{n}{n-1}\cdot  \ldots \cdot \frac{n}2\cdot n$$  so $\lim a_{n}\rightarrow \infty$ since $n<a_{n}$ for all $n>1$. Since the sequence is divergent, it follows that the function must be ultimately monotonic.  This feels a little dubious to me, I feel like I can form a much better argument than that, or at the very least a more elegant one. I've tried to assume $\{a_{n}\}$ approaches some limit $L$ so there exists some $N$ such that  $|a_{n} - L| < \epsilon$ whenever $n>N$ and derive a contradiction, but this approach got me nowhere.  Finally, I've also tried to use the fact that $\frac{a_{n+1}}{a_n}\rightarrow e$ to help me, but I couldn't find an argument where that fact would be useful.


Picture this situation. Myself and a friend are a pair of casters, both with familiars. My friend's familiar has just gotten in position next to an enemy we're fighting, and I know he intends to use his upcoming action to have the familiar deliver a touch range attack spell (such as Shocking Grasp), per Find Familiar...     Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an attack roll, you use your attack modifier for the roll.   My familiar's turn comes up, but I won't need its help when it's my turn for whatever reason. Instead, I want it to use the Help action to help my friend's spell land, so I order it to move next to...  ...who? The caster, or the familiar?

When I use the , do I choose the monster to distract (and then the next ally to attack gets advantage) or do I choose the ally and the monster (so that only his attack against that target gets advantage)? Or something else?  Help [...] Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you. You feint, distract the target, or in some other way team up to make your ally’s attack more effective. If your ally attacks the target before your next turn, the first attack roll is made with advantage.


Why is the trace impedance of a single-ended trace on a PCB fixed to 50 ohms or 75 ohms (for video signals)? Why can't it be fixed to any other impedance values?

Where does this number come from?  For single ended it must be 50 ohm and for differential pairs 100 ohm. Why?  For PCB with controlled-impedance these are that common numbers. Outside of the PCB you can find others numbers for characteristic impedance. But what is the reason of use these numbers for the PCB tracks?


Here is the error text I get when clicking install:  The following packages have unmet dependencies: libgl1-mesa-glx-lts-trusty: Depends: libglapi-mesa-lts-trusty (= 10.1.3-0ubuntu0.1~precise1) but 10.1.3-0ubuntu0.1~precise1 is to be installed                             Depends: libx11-6 (>= 2:1.4.99.1) but 2:1.4.99.1-0ubuntu2.2 is to be installed                             Depends: libxdamage1 (>= 1:1.1) but 1:1.1.3-2build1 is to be installed xserver-xorg-lts-trusty: Depends: xserver-xorg-core-lts-trusty (>= 2:1.11) but 2:1.15.1-0ubuntu2~precise1 is to be installed

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


The story takes place in the future; humans have colonized our galaxy but they encounter an alien race with which peace is impossible. Colonies start the war but Earth doesn't help them and decides to block the solar system entirely with space mines so nobody can enter. Decades pass and humans from the colonies are losing the battle against the aliens because they lack battleships, and the only way to win against the aliens is to fight the same way but with more battleships than them.  Finally, one day Earth sends a ship with a very small crew. All the crew member have developed special powers, like tactical genius, telepathy, and telekinesis. This ship goes to the planet of origin of the aliens and thanks to their power manages to convince the alien leader to attack Earth massively.      Half of the alien army goes to Earth. Too late they realize it’s a trap: the sun or Earth (not sure which) explodes, half of the alien army is wiped out, and then the human colonies can win the war. Earth has been sacrificed for the fate of the human race.   I think the alien race look like giant bats.  I think the author is American and the book was released from 1990 to 2005.  What book is this?

In the book, humans were in a long war with an alien race that had a slight upper hand in numbers and technology, and so were slowly losing ground.  At the start of the war, Earth had cut itself off from all contact with the rest of humanity; I think this was hundreds of years before the events in the book.  As the book opens, a single spaceship from Earth arrives at the human's capital world, IIRC to pick up an ambassador to travel to the alien's home world for peace negotiations.  Some more plot points dredged from memory:    The Earth ship had a small crew, somewhere around 4 or 5. The Earth humans had psychic powers, but galactic humans didn't. Earth had gone through a lot of social upheaval during its isolation from the rest of the galaxy. I think the aliens were telepathic (the Earth humans didn't tell the galactic ambassador about all their plans because he couldn't shield his thoughts).   The ending went along these lines:      After the peace mission, the aliens invade Earth with a large part of their military and trigger a booby trap that destroys them along with Earth.  After that, the balance of power is in humanity's favor.   If it helps, I would have read the book in the late 1970s or early 1980s, but I believe it was published some time before that.


When we reach a reputation of 15k, we are able to protect a question. Intention behind this privilege is preventing questions from getting non spam answers and low quality answers when the question is too popular.   But when a question is closed (not put on-hold) and there's no possibility of getting answered.         What is the point of adding an option to protect a closed question? Is it a feature intended as a preventive measure so that it will be protected even if a question is later reopened after some modifications?,

Since I've a database systems examination in less than 3 hours (from now), I have been browsing Stack Exchange network for questions with normalisation and related tags. Most of the questions are now closed as  or others from the list.  Since, these questions are closed, no users are allowed to post answers to them (unless they are reopened). Why am I, then, allowed the option to protect such questions? Doesn't that beat the entire purpose behind "protecting" a question?


else if (answer.equals("check value")){         System.out.println("Of what?");         System.out.println("Tax, Donations, Income, Profit, Expenditure, Services, Military, City or Economy.");         System.out.println("Do not use caps and spell it correctly otherwise it will not be recognised.");         String valueToCheck = scan.nextLine();         if (valueToCheck == "tax"){             System.out.println(tax);         }else if (valueToCheck == "donations"){             System.out.println(donations + "donations per turn");         }else if(valueToCheck == "income"){             System.out.println(incomePerTurn + " income per turn");         }else if(valueToCheck == "profit"){             System.out.println(profitPerTurn + " profit per turn");         }else if(valueToCheck == "expenditure"){             System.out.println(expenditurePerTurn + "expenditure per turn");         }else if(valueToCheck == "services"){             System.out.println(servicesBudget + " to services budget");         }else if(valueToCheck == "military"){             System.out.println(militaryBudget + " to military budget");         }else if(valueToCheck == "city"){             System.out.println(cityBudget + " to cities budget");         }else if(valueToCheck == "economy"){             System.out.println(economy  + " to total economy");         }         newTurn();}   Hello, whenever I run my program and type 'check value' I get no errors, in fact I get nothing. I am just wondering why nothing is returned. Thanks for any help!

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


I recently volunteered to help with a summer math program at a local high school for which I thought would be a breeze. As it turns out, it isn't a program for those catching up (summer school) like I thought, it's a small group of kids that have strong math skills and seem to have an endless desire for knowledge. I have been able to keep them reasonably in check intellectually, but I'm nearing the end of my bag of tricks.   For better or worse, they love mathematical fallacies. Of course they were familiar with showing $0=1$ (all numbers equal all other numbers fallacy), and after I showed them $1=-1$ through complex numbers I was out of ideas. I knew of the, all triangles are isosceles triangles fallacy, but couldn't remember it at the time. Does anyone have any interesting fallacies that I can show them? Their math knowledge goes through most of calculus but fallacies outside of that are fine too.  If this is a ridiculous question, I apologize. I figured there were more fallacies out there than what I could find on wikipedia and a few of the other top search results.  Thanks in advanced.  Note: I have another 3 weeks with them so no major rush.

In honor of April Fools Day $2013$, I'd like this question to collect the best, most convincing fake proofs of impossibilities you have seen.   I've posted one as an answer below. I'm also thinking of a geometric one where the "trick" is that it's very easy to draw the diagram wrong and have two lines intersect in the wrong place (or intersect when they shouldn't). If someone could find and link this, I would appreciate it very much.


There may already be answers for what I need to know, however, I cannot seem to make work what answers I do find.  So, I will ask anyways.  I have an image that is floral in design.  I have it saved as both a png and as a jpeg.  What I am wanting to do with it is make it into a picture frame by cutting out the center of it, leaving about an inch or so all around the edge.  I want the hole I cut out to be transparent so that I can either slide another pic underneath it or put it over the top of another pic.  When I am done, I will save it as a png.  I can use Adobe Illustrator, or Photoshop.  I really need some help please.

I would like to know how i can create a border (or rectangle with no fill) but with an image as the border lines.  Image example attached.  Can competently use Indesign, Illustrator or Photoshop so open to all.  Thanks


My husband was born in Iran. He is a naturalized US citizen and travels on his US passport. We are shortly to travel for tourism, returning through Turkey.  He holds an Iranian passport as well, which is only used when he goes to Iran to visit family, which he hopes to do in a few months. He uses that on the second leg of his flight when going there.   Have there been any problems with US citizens born in and/or traveling from one of the targeted countries being allowed re-entry into the US?

I'm a US citizen, born in the US, but also an Iranian citizen due to my father being from Iran. I've never been to Iran except for a brief time when I was just a year old.  In light of Trump's recent ban on citizens from 7 countries entering the US, if I decided to take a vacation to Europe in the near future, would I have trouble re-entering the US despite being an American-born US citizen?  Is there any way for airport officials to know that I even hold an Iranian citizenship?  I'm also concerned for my parents, who were both born in Iran but also hold US citizenships. Can we safely leave the country for vacation and come back?  We all have American passports.


The problem is simple: how to place a two-columns wide figure at the bottom of a page with the revtex document class? For those unfamiliar with revtex, it is a two-column style guide used by a number of physics journals.  I did extensive searching, only to find that many people face this problem (for example ).  For a non-revtex document the usual solution is using the stfloats or the dblfloatfix package. Revtex is however incompatible with both packages ( and ).  The revtex manual is also of no help with this problem.  I have been able to place a float at the position where I define it by wrapping it in the widetext environment, but this does improve readability.  A possible solution may be to use boxes in some way, but after some searching and trials I have not got this working.  The problem with the top placement is two-fold: - multiple two-column images clutter up at the top of a page - the text referring to the image(s) is lagging behind, forcing the reader to look at subsequent page(s) for the image.  So, anyone willing to pick up the challenge of solving this problem? A problem lasting for too long, for too many people.  Edit. A minimal working example as requested:  \documentclass[reprint, pre]{revtex4-1} \usepackage{graphicx} \usepackage{lipsum}  \begin{document} \lipsum[1] %I want the figure at the bottom of the first page and  %not on the top of the next page as it does now \begin{figure*}[b]     \centering     \includegraphics[width=\textwidth]{someImage.pdf}     \caption{Some caption here.}     \label{f:someImage} \end{figure*} \lipsum[1] \end{document}

I'm posting today because I would like to reduce white space in a document I'm writing. The content is two-columns but I have floating tables that span across both columns (table*).   At some point, the text ends in the beginning of the first column of a new page. I would like to include my table on this page since it has a lot of free space below the text, but when I insert the table* right after the text, it goes to the top of the next page instead:    Do you know a way of obtaining the desired behavior?  Minimal working example :  \documentclass{article} \usepackage{lipsum}  \begin{document} \twocolumn  \paragraph{} \lipsum[1]  \begin{table*} \centering \begin{tabular}{|c|c|c|c|} \hline Column 1 & Column 2 & Column 3 & Column 4 \\ \hline Column 1 & Column 2 & Column 3 & Column 4 \\ \hline \end{tabular} \end{table*}%   \end{document}


Let $G$ be a set with an operation $\ast:G\times G \rightarrow G$ such that:  (1) For all $a,b,c \in G$ we have $(a\ast b)\ast c=a\ast (b\ast c)$ (associativity),  (2) There is $e \in G$ such that $e\ast a=a$ for all $a\in G$ (left identity),  (3) For all $a \in G$ there is $a^{\prime}\in G$ such that $a\ast a^{\prime}=e$ (right inverse).  Show that $(G,\ast )$ need not be a group.  I can't think of a counter example that satisfies this not being a group.

This problem is from Herstein's 'Topics in Algebra'. I've thought about it a bit but haven't come up with much.  Let $G$ be a non-empty set with an associative product which also satisfies:   $\exists e\in G $ such that $\forall a \in G$, $a \cdot e=a$. Given $a \in G$, $\exists y(a) \in G$, such that $y(a) \cdot a =e$.   Prove that $G$ need not be a group.  I know that $G$ is a group if any one of those multiplications is switched around, i.e, either $a \cdot y(a)=e$ or $e \cdot a=a$. But I can't quite understand why in this case $G$ is not a group. I'd be much obliged if someone can give me a good explanation of why it must be and I'd also appreciate a counter-case if nothing else.   Thanks a lot. Cheers!


I wiped my entire system through the BIOS by restoring to default and now I want to install ubuntu on my laptop (64-bit Asus Zenbook). There's nothing on it, when I turn it on it automatically goes to the BIOS.   This is a completely new laptop and I actually installed ubuntu 12.04 on it before the reformatting, with the same bootable usb I'm using now. The laptop has a 24 GB SSD and a 500 GB HDD, it came with Win8 on the SSD and I didn't want Win on it, that's why I reformatted it. I can see both drives in the BIOS. When I installed 12.04 the first time, I placed it on the HDD. I'd like to put 12.04 on the SSD. The SATA is set to ACHI, so that should be ok.  I have a bootable USB with 12.04 and the laptop correctly shows the start menu where I can choose between trying ubuntu, installing ubuntu or checking the desk. No matter what option I pick, the screen just goes to black and nothing happens (I've waited more than 10 minutes).   What I can see is this   Any ideas? Do I need to install something before I can install ubuntu?  Thank you.   Info about the laptop: ASUS ZENBOOK UX32A R3013H Intel® Core™ i5 3317U Processor, Integrated Intel® HD Graphics 4000, 500GB HDD With 24 GB SSD

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


Can I import KML from  into QGIS 2.8.3?   I´m not sure with the duplication. I extracted KML file from KMZ and then I tried load into QGIS. Error message is in czech and it means data source is not in valid or is in unrecognized format, I added structure of kml file.

I know I can add KML files once I have unzipped the KMZ files, but is there a way to open KMZ files directly?   When I try to open a kmz file on QGIS 1.8.0 on Windows XP, through the all files filter, it does not accept it as a valid format.   Am I doing something wrong?   Does this all depend on OGR support?


I have a thumbnail image which I get from google drive API using code $service = new Google_Service_Drive($client); // Please use your "$client". $fileId = '1YVTIGaAvnzH5vF_B1t8-bKsW2Q8ymZBy'; // This is the file ID from your sample URL.  $res = $service->files->get($fileId, ["fields" => "name,thumbnailLink"]); $thumbnailLink = str_replace('=s220', '=s1000', $res->getThumbnailLink()); $name = $res->getName(); // file_put_contents($name . '.png', file_get_contents($thumbnailLink)); $image=file_get_contents($thumbnailLink);  I want to insert this image into MySQL database I have a table in which the image field is of type blob $sqlinsert="INSERT INTO $table (`Preview`) VALUES ($image) WHERE `Title`=$name"; $result=mysqli_query($conn,$sqlinsert);  I inserted the image into the database but it is giving error  You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '?PNG  ' at line 1  any idea how to solve it

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


$$\frac{1}{i} = \frac{1}{\sqrt{-1}} = \frac{\sqrt{1}}{\sqrt{-1}} = \sqrt{\frac{1}{-1}} = \sqrt{-1} = i$$  I know this is wrong, but why? I often see people making simplifications such as $\frac{\sqrt{2}}{2} = \frac{1}{\sqrt{2}}$, and I would calculate such a simplification in the manner shown above, namely  $$\frac{\sqrt{2}}{2} = \frac{\sqrt{2}}{\sqrt{4}} = \sqrt{\frac{2}{4}} = \frac{1}{\sqrt{2}}$$

I know there must be something unmathematical in the following but I don't know where it is: \begin{align} \sqrt{-1} &= i \\\\\ \frac1{\sqrt{-1}} &= \frac1i \\\\  \frac{\sqrt1}{\sqrt{-1}} &= \frac1i \\\\  \sqrt{\frac1{-1}} &= \frac1i \\\\  \sqrt{\frac{-1}1} &= \frac1i \\\\  \sqrt{-1} &= \frac1i \\\\  i &= \frac1i \\\\  i^2 &= 1 \\\\  -1 &= 1 \quad !!? \end{align}


I am adding a sub woofer into a room with 6 speakers (3 sets).  Each set of speakers is on an individual volume control wired back to a niles speaker hub. The speaker hub will be driven by an AudioSource AD508 8-channel multi-room digital power amplifier.  The speaker amp will get its line level signal from a Sonos Connect. (which I already have, and which does not have an output for a sub woofer.) . The sub-woofer has its own dedicated 300 watt amp which can take a speaker level input from the 8 channel speaker amp.  The AV cabinet is one floor below the room I am describing, so I need to be able to control the volume for the sub-woofer from the Sonos App as well as from the room with a hard wired volume control.(the way i can with the speakers)  I have teenage kids, so i need to be able to turn the volume down manually regardless of what they do intentionally or unintentionally when controlling the music from there mobile apps.  The cable run for the sub-woofer is direct from the AV cabinet to the subwoofer location.  This is done and cannot be modified.    I think I want to put a small potentiometer and knob directly above the sub-woofer sticking out through the gypsum board (drywall) for a very subtle but effective solution.  The sub woofer amp is 300 Watts.    Here are my questions: Am I correct that a potentiometer can be wired to work as a volume control? What is the spec for the potentiometer I need, given the 300 watt amp? Where do I get it? How do I wire it?  Is there a more elegant solution? (i do not want a wireless solution?)  Bonus Question: The wire from AV cabinet to Sub-woofer is a 4 conductor wire.  Is there a way to take advantage of the extra wires to create a better solution?  Thanks in advance

I have a Audio-Taper Potentiometer that I bought from RadioShack and would like to hook it up in-line to my sub woofer so my 5.1 surround sound's bass is not so loud.  However, the connections from the sub to the main receiver are proprietary plug on the back of receiver so I can't tell which is positive or negative.  Does this matter for hooking up a Potentiometer?  Where can I find a wiring diagram?


Let $K=\mathbb{Q}(\sqrt[3]{2})$ I want to show that $U(K)=\{\pm (\sqrt[3]{2} -1)^n : n \in \mathbb{Z}\}$   I know that an integral basis for $K$ is $1, \sqrt[3]{2}, \sqrt[3]{2}^2$  So far I have got: Since the minimal polynomial of $\sqrt[3]{2}$ has one real root and 2 complex roots then K has one real embedding and one complex embedding, so the signature of K is (1,1). The rank of K=1+1-1=1. Then by using Dirichlet's Unit Theorem there is some unit $u$ such that every other unit can be written in the form $\pm u^n$. Therefore $U(K)=\{\pm u^n\}$ but I don't know how to proceed from here.

I asked Wolfram Alpha to tell me the fundamental unit of $\mathbb{Z}[\root 3 \of 2]$, it replied $1 - \root 3 \of 2$. Then I tried asking it for $(1 - \root 3 \of 2)^n$ for $-5 \leq n \leq 5$. If I run $n$ over all the integers, does that give me all the units of this domain? Or does this give me some of the units and some non-units?


I'm preparing an essay which should contain the following letter:    I'm a newbie in the world of TEX, and I don't know how to get it. Can somebody help me?

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


As it is said, we use one (singular) and ones (plural) to avoid unnecessary repetition. But why can't we use one in the following sentences:   He used to work for a finance company, but he's moved to an insurance company. Why can't we say insurance one? On one channel was a war film and on the other was a horror film, so I turned the TV off. Why can't we say horror one?

I cannot make much sense of one in the following passage from :  Now the various species of whales need some sort of popular comprehensive classification, if only an easy outline one for the present, hereafter to be filled in all its departments by subsequent laborers.  If  is a noun in this passage, then  must serve here as a pronoun. If so, isn't the sentence lacking in punctuation? Rewriting would make it less ambiguous:  Now the various species of whales need some sort of popular comprehensive classification, if only an easy outline, one for the present hereafter to be filled in all its departments by subsequent laborers.  Furthermore, I can't help thinking that one is not needed here at all:  Now, the various species of whales need some sort of popular comprehensive classification, if only an easy outline for the present, hereafter to be filled in all its departments by subsequent laborers.  If Melville correctly worded this sentence, what is the function of one in it? What are your thoughts on my modifications?


I don't figure out how to tell printf to print a double with a variable precision.  Where is what I actually do :  int main(void) {     int digits = 4;      printf("%0.*f\n", digits, 0.123456789);     printf("%0.*f\n", digits, 5.9);      return (0); }   I actually have the variable precision with the * and the digits variable, but it still prints remaining 0 after the last number.  In order to illustrate my problem, here is what i get :  0.1234 5.9000   And here is what i want :  0.1234 5.9   Could you help me please?

I keep stumbling on the format specifiers for the printf() family of functions.  What I want is to be able to print a double (or float) with a maximum given number of digits after the decimal point.  If I use:  printf("%1.3f", 359.01335); printf("%1.3f", 359.00999);   I get  359.013 359.010   Instead of the desired  359.013 359.01   Can anybody help me?


I have this piece of code below :  in component_storage class :      template < typename T, typename... Args >     T& append( int index, Args&&... args )     {         grow();         T* result = (T*)m_data + m_size - 1;         construct_object<T>( result, std::forward<Args>( args )... );         if ( m_indices )             m_indices[ m_size - 1 ] = index;         return *result;     }   in component class :       template < typename Component, typename ...Args >     Component& add_component( handle h, Args&&... args )     {         component_interface* ci = get_interface<Component>();         auto* cs = get_storage<Component>();         int i = ci->m_index->insert( h );         assert( i == int( cs->size() ) && "Fail!" );         return cs->append<Component>( h.index, std::forward<Args>( args )... );     }   and I call add_component in main like this:       game_ecs e;     e.register_component< position >();     e.register_system< position_system >();      handle being = e.create();     e.add_component< position >( being, 3, 4 );   the problem is that I get those 2 errors :   error: expected primary-expression before ‘>’ token    return cs->append<Component>( h.index, std::forward<Args>( args )... );  error: expected binary operator before ‘)’ token    return cs->append<Component>( h.index, std::forward<Args>( args )... );   I am Compiling under Linux with g++ 7.2 with C++17 flags enabled. Any suggestions on this errors? I cannot find any solution.

In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway?    I have the following code:  template <typename T, typename Tail> // Tail will be a UnionNode too. struct UnionNode : public Tail {     // ...     template<typename U> struct inUnion {         // Q: where to add typename/template here?         typedef Tail::inUnion<U> dummy;      };     template< > struct inUnion<T> {     }; }; template <typename T> // For the last node Tn. struct UnionNode<T, void> {     // ...     template<typename U> struct inUnion {         char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U     };     template< > struct inUnion<T> {     }; };   The problem I have is in the typedef Tail::inUnion<U> dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion<U> names a type and not a function?


I am travelling to Canada with layovers at London and Dublin ( Mumbai - London - Dublin - Canada) with British Airways. I have an Indian passport and Canadian Student Visa. Both the layovers are below 3 hours. Will I be requiring a transit visa to catch the connecting flights from these airports? Ticket is on same booking id with same airlines.

Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.


I am importing a mesh into blender to modify some parts before I use it with babylonjs. What I am trying to achieve is to move all of the triangles from the selected (shown in the image below) to a seperate sub-mesh for each of the triangle.    The reason i want to do this is because using babylonjs I need to visualise a color change where if color is selected for a square, all of the others around it will have the same color base that fades out more the further the square is.

I've just made a set of armor by using a male body mesh model I downloaded and selecting certain faces from the model and duplicating them to create viable armor pieces.   Since the pieces are just duplicated from the same mesh male model, then it's still part of the same object.   How do I separate the armor piece from the model to make the pieces separate?


Suppose, a question can have two different answers in two sites, is it allowed?  Why is cross posting always discouraged?   Is it for saving the Stack Exchange system memory?  Or, to avoid Google returns multiple results for the same topic?

It is possible to migrate a question from one Stack Exchange site to another by closing, but if I have a question that I think is on-topic for multiple Stack Exchange sites, is it OK to post it on both (multipost)?   For example, I have a question that's earned me the tumbleweed badge on SO and I'm not sure what the best thing to do with it is. It's about a web server so it might be answerable on Server Fault but it's really more of a programming thing, hence the posting the question on Stack Overflow.    Is there any way to make the question visible on multiple sites (crosspost) and then accept the answer wherever it came from?


When I enter the password it gives me the following error:  login: root  Password: My-password Login incorrect   I have tried SSH via Putty as well as WinSCP. I get Network Error: Connection refused.  So what could have gone wrong?  Please advise.  Please Note: root is not the only user on this machine, I can access with another account and perform some command .  I tried to reset the root  password following the instructions on some other site. All went well, except I get the same error despite changing the password!  The last major thing I did was : create user , create group , associate the user to the group created and than change folder dir to the user inside etc/passwd. After that I start to have the root problem , so i cancel the user and the group created but i still facing the same problem

I am trying to virtualize an old linux server, and the PtoV software requires a password login as root via ssh. However, the root login is being prevented with a "Permission Denied" error on the client end, and a "Failed Password for root" on the server end (when sshd is running in debug mode).  I HAVE set PermitRootLogin yes in /etc/ssh/sshd_config.  This is an old RedHat 7.3 server that has had hardening scripts like Bastille run on it years and years ago, and has many remnants of old OS's (like ipchains - no longer supported by the kernel) lying around. All to say I have little idea what has been altered from the original system, but there is a lot.   I can log in fine as root from the console I can su to root fine from within the console or ssh session I can ssh fine as a regular user.   My question is: What else could be preventing my root login on this server?  More information: /etc/pam.d/sshd   auth       required     pam_stack.so service=system-auth  auth       required     pam_nologin.so  account    required     pam_stack.so service=system-auth  password   required     pam_stack.so service=system-auth  session    required     pam_stack.so service=system-auth  session    required     pam_limits.so  session    optional     pam_console.so   /etc/pam.d/system-auth  auth        required      /lib/security/pam_env.so auth        sufficient    /lib/security/pam_unix.so likeauth nullok auth        required      /lib/security/pam_deny.so account     required      /lib/security/pam_unix.so password    required      /lib/security/pam_cracklib.so retry=3 type= password    sufficient    /lib/security/pam_unix.so nullok use_authtok md5 shadow password    required      /lib/security/pam_deny.so session     required      /lib/security/pam_limits.so session     required      /lib/security/pam_unix.so     Can anybody tell me if the hashing algorithm could be the culprit?  Keeping in mind that I can log in as an unprivileged user.


While solving for the curl of the magnetic field($\vec \nabla\times \vec B = \mu_0 \vec J$), I got one formula which is written as $$\vec \nabla \cdot \frac{\hat r}{r^2} = 4\pi \delta^3 \vec r \tag{1}$$ and while solving for the verification of the Poisson's equation, I found the formula as follows $$\vec \nabla^2\frac{1}{\mid{\vec r - \vec r\:'}\mid} = -4 \pi \delta^3 (\vec r \:-\:\vec r\:')\tag{2}$$What are these equations called?  How do we get these equations (1) and (2)?  Can you please provide me the proof of these equations?

Let us define the magnetic field $$\vec{B} = g\frac{\vec{r}}{r^3}$$ for some constant $g$. How can we show that the divergence of this field correspond to the charge distribution of a single magnetic pole (monopole)?  EDIT:  If I calculate the divergence I get $$ \begin{align} \nabla\cdot\vec{B} &= \nabla\cdot\left(g\frac{\vec{r}}{r^3}\right) \\ &= g\left(\nabla\frac{1}{r^3}\right)\cdot\vec{r}+\frac{g}{r^3}\left(\nabla\cdot\vec{r}\right)\\ &=g\left(-3\frac{\vec{r}}{r^5}\right)\cdot\vec{r}+\frac{g}{r^3}(1+1+1)\\ &=-3g\frac{1}{r^3}+3g\frac{1}{r^3}\\ &= 0 \end{align} $$ which contradicts that there is a sink or source of magnetic flux.


I want to run a script that changes the hostname and have my bash prompt (PS1 variable) update immediately with the proper hostname.  How do I make this happen?  I run this  #!/bin/bash # Usage: ./changehost <newhostname>  #Do two sed's to edit the files for persistent hostname change sed -i s/$(hostname)/$1/g "/etc/hosts" sed -i s/$(hostname)/$1/g "/etc/sysconfig/network"  #run the hostname command with new hostname to update it hostname $1   In a terminal like so and get this  [user@host dir]# ./changehost newhostname [user@host dir]#    But what I want is this  [user@host dir]# ./changehost newhostname [user@newhostname dir]#    The terminal is updated properly only when I open up a new shell.  I've tried re-exporting the PS1 variable, and sourcing the /etc/bashrc in and out of the script (after it is run).  To reiterate, how do I get the shell that I run it in to update immediately?

This is a copy of my post from stackoverflow; I realize I should have asked it here...  I want to run a script that changes the hostname and have my bash prompt (PS1 variable) update immediately with the proper hostname. How do I make this happen?  I run this  #!/bin/bash # Usage: ./changehost <newhostname>  #Do two sed's to edit the files for persistent hostname change sed -i s/$(hostname)/$1/g "/etc/hosts" sed -i s/$(hostname)/$1/g "/etc/sysconfig/network"  #run the hostname command with new hostname to update it hostname $1   In a terminal like so and get this  [user@host dir]# ./changehost newhostname [user@host dir]#    But what I want is this  [user@host dir]# ./changehost newhostname [user@newhostname dir]#    The terminal is updated properly only when I open up a new shell.  I have also tried to do   export PS1='somestring'; export PS1='[\u@\h \W]\$'    outside of the script in the terminal and it does switch to 'somestring' and back, but the hostname is unchanged. :\   Is it possible that the \h is stored in memory when the process begins and can't be changed after startup?


shows the URL parsing bug I just encountered. It's pretty self-explanatory.

Further to Tim Stone's response to my  regarding what turned out to be an en dash in an URL: Would it be reasonable for markdown mini to replace en dashes with normal hyphens? Or is that Wikipedia article's URL just a fluke?


Today I installed Ubuntu along side windows 10. Everything seams fine apart from this wifi problem I'm having. The only way I can get an internet connection is through an Ethernet cable, because when I go to try and connect to a wifi network wirelessly the only thing I see is 'No Wifi adapter found'. I know that this is probably a driver problem, but I really don't know how to fix this. Any help is appreciated. Thanks in advance. EDIT: output of lspci -knn | grep Net -A3; rfkill list libkmod: ERROR ../libkmod/libkmod-config.c:656 kmod_config_parse: /etc/modprobe.d/iwlwifi.conf line 8: ignoring bad line starting with '“options' 04:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8821CE 802.11ac PCIe Wireless Network Adapter [10ec:c821]     Subsystem: AzureWave RTL8821CE 802.11ac PCIe Wireless Network Adapter [1a3b:3041]     Kernel modules: wl, rtl8821ce 05:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Picasso [1002:15d8] (rev c2)     Subsystem: ASUSTeK Computer Inc. Picasso [1043:18f1] 0: hci0: Bluetooth     Soft blocked: no     Hard blocked: no

We just bought a Lenovo  (which is supposed to have the Intel 8265 for wireless). This laptop was bought in part because it is certified to run Ubuntu and as such to me at least it would make sense for things to work out of the box... but no such luck.  First, I installed Ubuntu 17.10 and after installation realised Wi-Fi was not working. I also tried Ubuntu 16.04 from a USB drive since that is the version of Ubuntu it is certified for, but no luck there either.  The wireless chip is not detected by lshw (or even lspci by the looks of it), ip link does not show a wireless interface, and the iwlwifi kernel module is not loaded at boot (I can load this myself using modprobe iwlwifi but this does not make Wi-Fi work). I think it is a combined Wi-Fi/Bluetooth chip, and Bluetooth does appear to work (or at least Bluetooth shows up in Gnome and rfkill list).  modinfo iwlwifi | grep 8265 shows me a file ending in -34 is supposedly loaded but only a file ending in -33 (and some other lower numbers) is present in /lib/firmware, if that helps).  I have also installed the Linux 4.14.9 kernel in an attempt to get things to work, but this did not resolve the issue either.  Further information  root@ThinkPad-E570:~# modinfo iwlwifi | grep 8265 firmware:       iwlwifi-8265-34.ucode root@ThinkPad-E570:~# rfkill list all 0: tpacpi_bluetooth_sw: Bluetooth     Soft blocked: no     Hard blocked: no 1: hci0: Bluetooth     Soft blocked: no     Hard blocked: no root@ThinkPad-E570:~# dmesg | grep iwl root@ThinkPad-E570:~# lspci -nnk | grep 0280 -A3 05:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:c821]     Subsystem: Lenovo Device [17aa:c024]   Update  I just noticed that the laptop does not have an Intel wireless chip at all, but in fact has a Realtek one... which means that the  of the shop I bought this laptop at were not accurate... Sigh. Same problem stands, however, just with a crappier wireless chip.


was migrated from Server Fault to Unix & Linux with the answers.  is among the top network posts of . But the post shows only score with no title in the user profile.  And interestingly the link contains negative post id. When I click on the empty title, it redirects  to .

I discovered a strange, blank link in 's Top Network Posts:        The above link and screenshot are of the user's Unix & Linux site profile, but this issue can be reproduced on any of the user's site profiles other than Meta Stack Exchange (as the blank post appears to be on this site, and posts from the same site are excluded).  The link seems to go to , which features a really negative question ID (close to the lowest value that can be represented by a 32-bit signed integer, specifically -(2^31) + 1005), and lacks the title in the URL that is present in all of the other links. It leads to a 404 error.  Going to the  seems to go to an actual answer on a question migrated to this site, which happens to have a score of 13 (as of the time this was asked).  Why is the question ID incorrect here? Based on the duplicates, it seems that this affects posts (both questions and answers) that were migrated from other sites: somehow, the question ID seems to be getting messed up.  Update: It looks like the above linked user has deleted their account on this site, so the issue cannot be reproduced on the profile I originally reported. It can, however, be reproduced on . The errant link in that profile is , and the errant question ID seems to also be close to the lowest possible 32-bit signed integer, -(2^31) + 3412.


I know it may sound stupid but I'm just genuinely wondering about it....  $$\frac ab\times\frac1c=\frac a{bc}$$ where $b,c\ne0$.  How can we multiply numerators by numerators and denominators by denominators?  Is it just a rule? Or can it be proved?

Why multiplying fractions is equal to multiply the tops, multiply the bottoms? $$\frac{a}{b}\times \frac{c}{d}=\frac{a\times c}{b \times d},$$ And why $$\frac{a}{b}\times \frac{c}{c}=\frac{a}{b},$$ Also why $$\frac{a}{b}+\frac{c}{b}=\frac{a+c}{b}.$$ I understand it, but I want a mathematical approach as a math student proves it. Also I want to know the mathematics topic of this question (number theory, logic, etc). A full answer is not necessary. Just a reference.


Im having problems with RegEx in preg_match (php). Im using this code:  $str = 'text code-product?key=1Jh49XPA8qRzi1-lINwt7TB9CO&action=edit'; //print -> 1Jh49XPA8qRzi1-lINwt7TB9CO //$str = 'text code-product?key=1Jh49XPA8qRzi1-lINwt7TB9CO'; //print -> 1Jh49XPA8qRzi1-lINwt7TB9CO //$str = 'text code-product?key=1Jh49XPA8qRzi1-lINwt7TB9CO&action=delete'; //print -> 1Jh49XPA8qRzi1-lINwt7TB9CO  preg_match('/product\?key\=(.*)(\&|$)/', $str, $match); $id = isset($match[1]) ? $match[1] : null;  echo $id;   When I try to get the ID, it not always work. I need get the ID between product?key= and the last & (if it exists). Thx so much.

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


Is there a good program, either online or to download, to write nicely mathematical papers using the same LaTeX versions as in mathexchange, or as close to it as possible?  I've seen something called MikTex or Tex Live, but I am not sure whether those are good programs. It would be nice to have the finished files in PDF if possible, though I guess DJVU or even word could be an option.

I've used LaTeX a lot in the past, but now, when comparing with StackExchange's great , I find it tedious, for short documents (< 2 pages), to have to use pure LaTeX. For a short document, instead of having 30 lines as introduction: \begin{document} \documentclass[11pt,a4paper]{article} \usepackage[frenchb]{babel} \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc} \usepackage{amsmath} \usepackage{amsfonts}  + <lots of other things> ...  I'd like to write my short document with MarkDown + Math, like on . Question: Is there an offline compiler such that compilemarkdown exercice.tex  would produce a PDF from this: #Title  Here is a *short document* including Markdown and Math, here is the equation:  $$f(x)=x^2$$  ___  Proof: ...   This is **bold**.


Such that only up to N licenses can be shared between 5 x N users on different computers at the same time?

This is a  about Licensing.    Questions on licensing are off-topic on Server Fault.  If your question has been closed as a duplicate of this question, then this is because we want to help you understand why licence questions are off topic rather than just telling you "it just is". In all likelihood, this question will not address your question directly, it was not meant to.    I have a question regarding software licensing. Can the Server Fault community please help with the following:   How many licenses do I need? Is this licensing configuration valid? What CALs do I need to be properly licensed? Can I run this product in a virtual environment? Can I downgrade this product to an earlier version? Am I entitled to feature X with license Y?


Lehman Brothers (is/are) now taken over by some other company.   My answer is is.   My approach to finding the correct answer is that according to subject–verb agreement rules, if both of them refer to same subject, we use a singular verb. Thus:     Lehman Brothers is now taken over by some other company.   Is my approach right according to subject–verb agreement rules?

Possible Duplicate:          Frequently when reading tech articles, I see sentences like "Microsoft have released ..." or "Apple have announced ...". This seems wrong to me because the nouns are singular; Microsoft and Apple are individual companies, even though they refer to groups of people. I have not seen this usage outside of tech journalism, but it's pervasive enough that it makes me wonder: is this actually the correct usage?  As a follow-up question, is it correct to use a plural pronoun for a singular antecedent like this? For example, "Apple has announced they are changing their name to Orange" or "Apple has announced it is changing its name to Orange". The second form seems technically correct but sounds awkward.


Hardback books take up so much room I don't have.... is there a legal PDF somewhere I can purchase?

As much as I like having the hardcover core rule-books in front of me, usually I read or reference most information for RPGs on my computer.  Unfortunately, my google-fu has failed me at finding places to buy a Player's Handbook PDF, or even whether said PDF exists at all.  My question is this: Is there any place I can go to legally buy a D&D 5e core rulebook PDF?  I'm not looking for the starter set or basic rules, since those are incomplete (and free), I'm just looking for the core books in PDF format.


Suppose we have $\gcd(x,z) = 1$, prove that $\gcd(xy, z) = \gcd(y,z)$. This appears very intuitive to me however is there a formal way of proving this?   I could write the obvious statement that since $z$ does not have a common divisor as $x$, then the only common divisor comes from $y$. So this means that $\gcd(xy, z) = \gcd(y,z)$ directly. However, this does not seem mathematical enough, is it?

How can I prove that if $\gcd(a, b) = 1$, then $\gcd(ab, c) = \gcd(a, c) \times \gcd(b, c)$?  By eea there exists $ax+by=1$ from $\gcd(a,b)=1$ so a and be are co-primes there also exists $dk=a$ and $dj= b$ where $d=\gcd(a,b)=1$ this is all the information I have gathered from the question but I dont know how to approach and solve it. Can anyone help explain to me how to arrive at the answer? Thanks!


A ten year comparison between the United States and the Soviet Union   in terms of crop yields per acre revealed that when only planted   acreage is compared, Soviet yields were equal to 68 percent of United   States yields. When total agricultural acreage (planted acreage plus   fallow acreage) is compared, however, Soviet yield was 114 percent of   US yield. From the information above, show that a higher percentage of   total agricultural acreage was fallow in United States than in the   Soviet Union.   I keep falsely calculating a result in my process of solving the problem such that the United States has more fallow land than the Soviet Union, but I know this is wrong conclusion by proof by contradiction.

A ten year comparison between the United States and the Soviet Union   in terms of crop yields per acre revealed that when only planted   acreage is compared, Soviet yields were equal to 68 percent of United   States yields. When total agricultural acreage (planted acreage plus   fallow acreage) is compared, however, Soviet yield was 114 percent of   US yield. From the information above, show that a higher percentage of   total agricultural acreage was fallow in United States than in the   Soviet Union.   Proof:  Let $USP$ for US planted and $SUP$ for Soviet Union planted. The same for $USF$ and $SUF$. We know that $SUP/USP= 0.68.$  How does the sentence     When total agricultural acreage (planted acreage plus fallow acreage)   is compared, however, Soviet yield was 114 percent of US yield.   imply that  $(SUF+SUP)/(USF+USP)= 1.14$? (that's the next step of the proof which is the part I'm stuck)


Forgive me, for I am not very eloquent.   If someone were to tell a bad joke  but in the given scenario it got some laughs and could be recounted as a “good joke” then the joke was _____.   On the surface and out of context, the object of the sentence (in this case the joke) was bad, but in the given situation it was actually good, what would be a word to describe that?   When something could be described as one thing, but in a certain situation it is exactly the opposite. It would be _____.

I wish to state that my exposure to a certain area was a mere coincidence, and I am happy about the area.   Moreover, I want to convey the idea that the incident was like a fairytale, something no one would easily believe, but because of it I ended up where I am.  The same incident happening to someone else might go unnoticed but it rang the bells for me.  Stating this idea as above is too long and boring, and such language seems childish or out-of-place in a statement of purpose. I want to make it succinct.  Is there any word or phrase that conveys the same idea?


I'm new to Python, and need to create a list with multiple instances of a data class.  I tried using list multiplication to do this, because I figured it would be faster since I'd have to 'append' thousands of individual instances of my data class.  However, my list multiplication seems to create objects that all reference the same instance of my data class, rather than to multiple independent instances of my data class. Here's the simple example that I tried: class Test:                 # define data class "Test".    def __init__(self, a):       self.a = a  test = Test(1)              # define an instance of data class "Test".  tests = [test] * 2          # define a list called "tests", with 2 instances of "test". print(tests[0].a)           # both instances of 'a' in the list show that "a = 1". print(tests[1].a)  tests[0].a = 2              # change the first instance of 'a' in the list to "a = 2". print(tests[0].a)           # first instance of 'a' properly changed to "a = 2". print(tests[1].a)           # but, the second instance of 'tests.a' ALSO changed from 1 to 2!  I had expected that changing one instance in the list wouldn't affect the other instance, but it looks like what I actually have is multiple copes of the same instance.  So, how can I create a list with multiple, independent instances of my data class "Test"?

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?