A lot of people use random.seed() at the beginning of their python code in training a machine learning model. As I understand they want to control the randomness therefore they can compare different hyper-parameters, but as demonstrated in the following piece of python code, the random int number is controlled only when you set seed every time before you use it. Why do they bother to set seed if it did not control the randomness in the training process? >>> random.seed(5) >>> random.randint(1,10) 10 >>> random.randint(1,10) 5 >>> random.seed(5);random.randint(1,10) 10 >>> random.seed(5);random.randint(1,10) 10  Example of set seed code def set_seed(seed: int = 42):     random.seed(seed)     np.random.seed(seed)     os.environ["PYTHONHASHSEED"] = str(seed)     torch.manual_seed(seed)     torch.cuda.manual_seed(seed)  # type: ignore     torch.backends.cudnn.deterministic = True  # type: ignore     torch.backends.cudnn.benchmark = True  # type: ignore  The set_seed has been called only once.

In almost all of the analysis work that I've ever done I use:   set.seed(42)    It's an homage to Hitchhiker's Guide to the Galaxy. But I'm wondering if I'm creating bias by using the same seed over and over.


I get error messages in black screen. Timeouts and errors. The error on my Windows XP Dell D830 laptop looks very similar as seen in . The Dell D830 laptop has a dual-core Intel processor with 64-bit support.

I'm trying to install Ubuntu 18.04 desktop with Rufus on a computer with the following specs:  CPU: AMD Ryzen 5 2600 MOBO: ASUS Prime B450M-A/CSM RAM: G-Skill Ripjaws DDR4 F4-2400C15D-16GVB GPU: Nvidia GeForce GTX750 PSU: Apexgaming AG-650M SSHD: Seagate Firecuda Compute mATX: Rosewill SCM-01  Basically it boots from the USB (FAT32) and brings up a black error screen with words and numbers. Then it transitions to the purple splash screen with "ubuntu" and 5 dots, however the screen shows various visual glitches depending on which USB port I plug into. When trying to boot the computer, it boots to a black screen with the following error message: ACPI Error: Needed [Integer/String/Buffer], found [Region]    that shows what I mean.


I am having some trouble using the new Source Han Sans font (; ) released by Google and Adobe in latex documents. I compile using XeLaTeX and have the TeX Live installation. I have spent the last 4 hours or so looking for a solution but couldn't find one.  My code is the following:  \documentclass{article} \usepackage{xeCJK} \setCJKmainfont{Source Han Sans J Normal} \renewcommand{\arraystretch}{1.5} \setlength\parindent{0pt} % Removes all indentation from paragraphs \topmargin=-0.45in \evensidemargin=0in \oddsidemargin=0in \textwidth=6.5in \textheight=28cm \headsep=0.25in  \footskip = 20pt \begin{document} \thispagestyle{empty} 日本 \end{document}   Now when I run this it doesn't give me an outright error. However when I try to open the compiled pdf it tells me it is broken. When I look at the log file I find this at the bottom (the file name is "Core 1000 1-10.tex"):  Error 1 (driver return code) generating output; file Core 1000 1-10.pdf may not be valid.   The complete .log file can be found here:   When I comment out the line \setCJKmainfont{Source Han Sans J Normal} it works correctly again.  I have installed all the fonts in the family and did the procedure to load new fonts into LaTeX using TeX Live-manager.  Is this font maybe just not supported by xeCJK or am I doing something wrong?

I was trying to find a font which has obsolete jamo and the right combining behaviour. Yesterday I found out about , which seems to have both of these. However, when I use it in XeTeX, I get some seemingly-arbitrary hanja (or blank spaces) instead of the expected characters.  (I’m guessing the composing behaviour will fix itself when the right characters are selected. And yes, I know that Code2000 is working perfectly in this example, but unfortunately it is the ugliest font in the world. :p)  MWE:  \documentclass{article} \usepackage{fontspec}  % 1. precomposed: U+BB47 % 2. separate jamo: U+1106, U+116E, U+11BA % 3. obsolete [separate jamo]: U+113B, U+119F, U+11EB \newcommand\test[1]{#1 & {\fontspec{#1}{뭇; 뭇; ᄻᆟᇫ}} \\}  \begin{document}  \begin{tabular}{rl} \test{Arial Unicode MS} \test{Batang} \test{Code2000} \test{Gulim} \test{GungSeo} \test{HeadLineA} \test{Nanum Brush Script} \test{Nanum Myeongjo} \test{Nanum Pen Script} \test{Noto Sans Korean} \test{PCMyungjo} \test{PilGi} \test{Adobe Gothic Std} \test{Adobe Myungjo Std} \test{Apple SD Gothic Neo} \test{AppleGothic} \test{AppleMyungjo} \end{tabular}  \end{document}


The database design for a retail organization has several tables with image columns. These account for around 40% of the table size due to their large size.  (Many a DBA issues come from inheriting the existing environment).  This is a production database.  I would like to know of a way to archive the current images from the database. Is there a better way besides FILESTREAM to  store or have access to image files than this?  I am thinking of a column with link to file system where the image is stored.  How does one get to that point? Can someone point me in the right direction

What is the best place for storing binary files that are related to data in your database? Should you:   Store in the database with a blob Store on the filesystem with a link in the database Store in the filesystem but rename to a hash of the contents and store the hash on the database Something I've not thought of   The advantages of (1) are (among others) that atomicity of transactions is preserved. The cost is that you might dramatically increase storage (and associated streaming/backup) requirements  The goal of (3) is to preserve atomicity to some degree - if you can enforce that the filesystem you are writing to does not allow files to be changed or deleted, and always has the correct hash as filename. The idea would be to write the file to the filesystem before permitting the insert/update referencing the hash - if this transaction fails after the filesystem write but before the database DML, that is fine because the filesystem is 'faking' being the repository of all possible files and hashes - it doesn't matter if there are some files in there that are not being pointed to (and you could clean them up periodically if you are careful)  EDIT:  It looks like some RDBMSs have this covered in their individual ways - I'd be interested to know how others do it - and particularly in a solution for postgres


I've seen quite a few proofs already that demonstrate that any function $f$ can be written as the sum of an even and odd function. I'm trying to prove this result by dividing into cases where $f$ is even, $f$ is odd, and $f$ is neither even nor odd. But I'm having trouble with the case where $f$ is neither even nor odd.  This is the construction of the proof so far:  By definition a function $f$ is even if $f(x)=f(-x)$ and odd if $f(x)=-f(-x).$ From a previous result, the sum of two even functions is even, the sum of two odd functions is odd, and the sum of an even and odd function is neither even nor odd.  $f$ is even: $f(x)=\dfrac{f(x)+f(x)}{2}=\dfrac{f(x)+f(-x)}{2}+0=\dfrac{f(x)+f(-x)}{2}+\dfrac{f(x)-f(-x)}{2}$  $f$ is odd: $f(x) = \dfrac{-f(x)-f(x)}{-2}=0 +\ \dfrac{-f(x)+f(-x)}{-2}=\dfrac{f(x)+f(-x)}{2}+\dfrac{f(x)-f(-x)}{2} $  How would I go about showing that a function $f$ which is neither even nor odd can be written as the sum of an even function $\biggl(E(x):=\dfrac{f(x)+f(-x)}{2}\biggr)$ and an odd function $\biggl(O(x):=\dfrac{f(x)-f(-x)}{2}\biggr)$?

What is the logic/thinking process behind deriving an expression for even and odd functions in terms of $f(x)$ and $f(-x)$?  I've been pondering about it for a few hours now, and I'm still not sure how one proceeds from the properties of even and odd functions to derive: $$\begin{align*} E(x) &= \frac{f(x) + f(-x)}{2}\\ O(x) &= \frac{f(x) - f(-x)}{2} \end{align*}$$ What is the logic and thought process from using the respective even and odd properties, $$\begin{align*} f(-x) &= f(x)\\    f(-x) &= -f(x) \end{align*}$$   to derive $E(x)$ and $O(x)$?    The best I get to is: For even: $f(x)-f(-x)=0$ and for odd: $f(x)+f(-x)=0$  Given the definition of $E(x)$ and $O(x)$, it makes a lot of sense (hindsight usually is) but starting from just the properties. Wow, I feel I'm missing something crucial.


I would like to know how much time does it take to translate a manga volume (e.g. One Piece) to another language, for example English or Spanish.

As far as I know, the English versions of tankoubon volumes for most manga series seem to be released within several months, if not years, of their original release in Japanese.  Even very popular mainstream series like Naruto and Fairy Tail have their English tankoubon counter-parts released months after their initial Japanese release.  Why is this the case?   If you consider the time it takes for subbed anime to be released, or even the (legal) translation of individual manga chapters done by companies like Crunchyroll or Shonen Jump, which happens on the order of days from the initial Japanese release,  it doesn't make much sense to me that releasing an English translation of tankoubon volumes would take so long, especially in the case of individual translation of the chapters, since all the companies would have to do is just compile them together.


I recently downloaded blender 2.91.0 I did a little lightsaber and, when I go to material preview, it just becomes all grayed out, and when I add a new material the color of the material doesn't change screenshot:

I don't know why but now, when i go in material preview or rendered (in solid mode it works fine), my object is entirely gray, or invisible idk, because it has the same color of the background. I've been working for days on this project without having this issue, it suddenly showed up. I tried opening other old projects and suddenly they all do the same so i guess it is some blender program setting that applies for all the projects, but idk how it happened cuz i didn't change anything :/, anyone got any tips?


Im just now getting into python, and my assignment is to write a Celsius to Farenheit (and vice versa) converter. I get bonus points for having the degree symbol incorporated.  I want to have degree_symbol show up in the text of the initial input question  degree_symbol = chr(176) temperature = input("Is your temperature in", degree_symbol, "F or", degree_symbol, "C?\n")  if temperature == "C":     temp_c = float(input("What is your temperature in C?\n"))     print("That is", ((temp_c * (9/5)) + 32), degree_symbol, "F!")   else:     temp_f = float(input("What is your temperature in F?\n"))     print("That is", ((temp_f - 32) * (5/9)), degree_symbol, "C!")     this is the error that shows up      3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:43:06) [MSC v.1600 32 bit (Intel)] Python Type "help", "copyright", "credits" or "license" for more information. [evaluate -------_As01.py] Traceback (most recent call last):   File "C:/Users/-----------/----------_As01.py", line 10, in <module>     temperature = input("Is your temperature in", degree_symbol, "F or", degree_symbol, "C?\n") builtins.TypeError: input expected at most 1 arguments, got 5

I want to do something like String.Format("[{0}, {1}, {2}]", 1, 2, 3) which returns:  [1, 2, 3]   How do I do this in Python?


Im a beginner programmer and i want to make a copy function that clones an array in to another one, for example: if i have this array already declared [1,2,3,4,5] i want the function to clone that array. Here is my code but when compiling im obtaining the array address. By the way im not programming with objects yet. static int[] copy(int[] collection) {      int  result[] = new int [collection.length];         for(int i = 0; i<collection.length; i++) {         result[i]=collection[i];     }      return result; }  if i print it like this i obtain the address, something like "[I@76ccd017" public static void main(String[] args){     int[] nums = {1,2,3,4,5};     System.out.println(copy(nums));  }

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]


what is the advantage of presenting area-standardised rate instead of crude rate when comparing different countries?  Would the answer be that it helps to control for confounding (where area is a confounder)? Or is it that it allows different countries with different distributions to be compared?   Appreciate if someone can help, thank you.

I'm just being curious, i have seen on some places, statistical results where they give them in form of "10 of 100.000" or "5 of every 10".  I don't have any statistical knowledge over my personal experience/reading around. But basic maths tell me that such values could be simplified as any fraction we used to do:  10 of 100.000 -> 1 of 10.000 // 5 of every 10 -> 1 of every 2.  Is there any reason not to do it?  Edit:  The numbers come from, if i remember correctly:   10 of 100.000 people per year  with some bad reaction to medication 5 of every 10 people who actively smokes on ¿Spain?


I'm developing an app which works with phone numbers, but I'm having a problem using regex to find the phonenumber in a string.  My app looks through the contact's phone number which can be:  (with dash "-") XXXX-XXXX XXXXX-XXXXX (YY) XXXX-XXXX (YY) XXXXX-XXXX +ZZ (YY) XXXX-XXXX +ZZ (YY) XXXXX-XXXX  (without dash) XXXXXXXX XXXXXXXXX (YY) XXXXXXXX (YY) XXXXXXXXX +ZZ (YY) XXXXXXXX +ZZ (YY) XXXXXXXXX  Based on all this possibilities above, I've written the following code:      let range = telefone.rangeOfString("[0-9]{4,5}-[0-9]{4}", options:.RegularExpressionSearch)     let range2 = telefone.rangeOfString("[0-9]{9}$", options:.RegularExpressionSearch)      var found: String?      if range != nil{         found = telefone.substringWithRange(range!)     }else if range2 != nil{         found = telefone.substringWithRange(range2!)     }      print(found)   range is the regex to find phoneNumbers (with dash "-") range2 is the regex to fund phone numbers (without dash)  With this code I get only the phone number, without the country code or the area code.  The problem is, this code returns nil on found variable when I test with a phone number like  +ZZ (YY) XXXXX-XXXX  Can someone help me find another way to write a regex to get only the "X" values of the string containing all the contact phone number?   UPDATE:  I noticed the code above, the variable range, returns null      var telefone = "+42 43 23123-2221"      let range = telefone.rangeOfString("\\d{4,5}\\-?\\d{4}", options:.RegularExpressionSearch)      print("range \(range)")   //here returns nil

I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant.


I need to extract the current date and time from the system and create SQL queries using a range of dates.  As i am running this on Windows, it will have to be a dos batch script.  Is there a way a can get the date and time in the DDMONYY,HH:MI:SS format? (e.g. 14MAR11,14:25:26)  I would like to generate ten dates in that format with each being 1 minute later than the previous date and time.   I am not an expert in dos scripting but i have found out how to write a loop in dos but not quite sure how to generate the date in the format i want it to be:  for /L %%i in (1,1,10) do (      currentDate = currentDate + one minute     echo "Insert into dateValue(ArrivalDates) values(%currentDate%)" > insert%i%.sql  )   Thanks in advance

Update: Now that it's 2016 I'd use PowerShell for this unless there's a really compelling backwards-compatible reason for it, particularly because of the regional settings issue with using date. See @npocmaka's     What's a Windows command line statement(s) I can use to get the current datetime in a format that I can put into a filename?  I want to have a .bat file that zips up a directory into an archive with the current date and time as part of the name, for example, Code_2008-10-14_2257.zip. Is there any easy way I can do this, independent of the regional settings of the machine?  I don't really mind about the date format, ideally it'd be yyyy-mm-dd, but anything simple is fine.  So far I've got this, which on my machine gives me Tue_10_14_2008_230050_91:  rem Get the datetime in a format that can go in a filename. set _my_datetime=%date%_%time% set _my_datetime=%_my_datetime: =_% set _my_datetime=%_my_datetime::=% set _my_datetime=%_my_datetime:/=_% set _my_datetime=%_my_datetime:.=_%  rem Now use the timestamp by in a new ZIP file name. "d:\Program Files\7-Zip\7z.exe" a -r Code_%_my_datetime%.zip Code   I can live with this, but it seems a bit clunky. Ideally it'd be briefer and have the format mentioned earlier.  I'm using Windows Server 2003 and Windows XP Professional. I don't want to install additional utilities to achieve this (although I realise there are some that will do nice date formatting).


I have a problem with that error "undefined reference". I can't find any solution to fix that. I just write a simple AVL tree program. My AVL.h  template <class Record> class AVL_tree { public:     AVL_tree();     ~AVL_tree();     Error_code insert(const Record &new_data);     Error_code remove(const Record &old_data);     bool empty();     void printLNR(); private:     Error_code avl_insert(AVL_node<Record> *&sub_root,                           const Record &new_data, bool &taller);     Error_code avl_remove(AVL_node<Record> *&sub_root,                           const Record &old_data,bool &shorter);     void rotate_left(AVL_node<Record> *&sub_root);     void rotate_right(AVL_node<Record> *&sub_root);     void left_balance(AVL_node<Record> *&sub_root,bool &changeHeight);     void right_balance(AVL_node<Record> *&sub_root,bool &changeHeight);      AVL_node<Record> *root;     void destroy(AVL_node<Record> *);     void printLNR_recursive(AVL_node<Record> *); };   My AVL.cpp file:  #include <iostream> #include "AVL.h" using namespace std; //--------------------------------------------------------- template <class Record> AVL_tree<Record>::AVL_tree() {     root = NULL; } //--------------------------------------------------------- template <class Record> AVL_tree<Record>::~AVL_tree() {     destroy(root);     root = NULL; } //--------------------------------------------------------- template <class Record> void AVL_tree<Record>::destroy(AVL_node<Record> *subroot) {     if (subroot != NULL) {         destroy(subroot->left);         destroy(subroot->right);         delete subroot;     } }   I just try to create a new obj named Sample in main.cpp but I got this error:     D:/AVL/main.cpp:8: undefined reference to AVL_tree<int>::AVL_tree()'   D:/AVL/main.cpp:8: undefined reference toAVL_tree::~AVL_tree()'   My main.cpp file:  #include <iostream> #include "AVL.h"  using namespace std;  int main() {     cout << "Hello, World!" << endl;     AVL_tree<int> Bee;      return 0; }

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


Let $N\neq 1$ be a normal subgroup of G, where G has order $p^n$, $p$ prime, $n\geq 1$.  I need to show that $Z(G)\cap N\neq \{1\}$.  I have tried to do it this way: Suppose $|N|=p^m$, $m<n$. Since $N\cap Z(G)$ is normal in $Z(G)$, in both cases ($N\cap Z(G)=\{1\}$ and $N\cap Z(G)\neq\{ 1\}$), I used the Second Group Isomorphisms Theorem to get:  $G/N\cong Z(G)/N\cap Z(G)$  so $|G/N| = |Z(G)/N\cap Z(G)|$  Since N is normal in G, $|G/N|=p^{n-m}$, with $n-m>0$. So $|Z(G)/N|\cap Z(G)|=p^{n-m}\Rightarrow [Z(G):N\cap Z(G) ]=p^{n-m}$  and this means that $N\cap Z(G)\neq \{1\}$.

If $G$ is a finite $p$-group with a nontrivial normal subgroup $H$, then the intersection of $H$ and the center of $G$ is not trivial.


I have set 000 permission for a single file writing this code:  sudo chmod 000 ./Desktop/*.gif   But still this file is deletable and renameable (but not readable).  Although this code:  sudo chmod 000 ./Desktop/Directory_name   makes the directory inaccessible (read,write,execution protected).   What's wrong ?

First of all, I'm not looking for an answer on how to remove the files. I am looking for a reason why this doesn't work - and a suggestion on how to remove the files without sudo.  I have a directory in my Desktop that has a few inner directories (don't judge the naming - I just extract what I need from files I'm given) and after getting the files I try and remove the files with rm -rf Bengal\ Tiger\ Creative/, I am surprised to see the following warning for each image.     rm: cannot remove ‘Bengal Tiger Creative/Bengal Tiger Creative/images/customer-services-landscape.jpg’: Permission denied   Below is some code outputs.  tree  nathan@nathan-pc:~/Desktop$ tree . ├── Bengal Tiger Creative │   └── Bengal Tiger Creative │       └── images │           ├── awards.jpg │           ├── blank.gif │           ├── bullet1-light-green.gif │           ├── bullet2-light-green.gif │           ├── bullet3-light-green.gif │           ├── bullet4-light-green.gif │           ├── customer-services-landscape.jpg │           ├── desktop.ini │           ├── header-img1.jpg │           ├── header-img2.jpg │           ├── header-img4.jpg │           ├── header-img5.jpg │           ├── softhr.gif │           ├── Thumbs.db │           ├── tiger_main-img1.jpg │           ├── tiger_main-img2.jpg │           ├── tiger_main-img3.jpg │           ├── tiger_main-img4.jpg │           ├── Vanquis-benefits-icons_iphone-green.gif │           └── white-arrow-green.gif   ls -laR  nathan@nathan-pc:~/Desktop$ ls -laR Bengal* Bengal Tiger Creative: total 12 drwxrwxr-x 3 nathan nathan 4096 Aug 10 11:30 . drwxr-xr-x 6 nathan nathan 4096 Aug 10 11:34 .. drwxrwxr-x 3 nathan nathan 4096 Aug 10 11:34 Bengal Tiger Creative  Bengal Tiger Creative/Bengal Tiger Creative: total 12 drwxrwxr-x 3 nathan nathan 4096 Aug 10 11:34 . drwxrwxr-x 3 nathan nathan 4096 Aug 10 11:30 .. dr-xr-xr-x 2 nathan nathan 4096 Aug 10 11:36 images  Bengal Tiger Creative/Bengal Tiger Creative/images: total 356 dr-xr-xr-x 2 nathan nathan   4096 Aug 10 11:36 . drwxrwxr-x 3 nathan nathan   4096 Aug 10 11:34 .. -rwxrwxrwx 1 nathan nathan  14910 Mar 18 12:29 awards.jpg -rw-rw-r-- 1 nathan nathan   1093 Mar 21  2014 blank.gif -rw-rw-r-- 1 nathan nathan   1978 May  8  2014 bullet1-light-green.gif -rw-rw-r-- 1 nathan nathan   1969 May  8  2014 bullet2-light-green.gif -rw-rw-r-- 1 nathan nathan   2416 May  8  2014 bullet3-light-green.gif -rw-rw-r-- 1 nathan nathan   2449 May  8  2014 bullet4-light-green.gif -rw-rw-r-- 1 nathan nathan 113138 Apr 14  2014 customer-services-landscape.jpg -r--r--r-- 1 nathan nathan    142 Mar 25 11:58 desktop.ini -rw-rw-r-- 1 nathan nathan  14312 Mar 23 11:39 header-img1.jpg -rw-rw-r-- 1 nathan nathan   1480 Mar 23 11:41 header-img2.jpg -rw-rw-r-- 1 nathan nathan   1278 Mar 23 11:41 header-img4.jpg -rw-rw-r-- 1 nathan nathan   1168 Mar 23 11:41 header-img5.jpg -rw-rw-r-- 1 nathan nathan   1703 Mar 21  2014 softhr.gif -rw-rw-r-- 1 nathan nathan  88064 Aug  4 10:39 Thumbs.db -rw-rw-r-- 1 nathan nathan  23607 Mar 23 11:56 tiger_main-img1.jpg -rw-rw-r-- 1 nathan nathan  23400 Mar 23 11:56 tiger_main-img2.jpg -rw-rw-r-- 1 nathan nathan   6970 Mar 23 11:56 tiger_main-img3.jpg -rw-rw-r-- 1 nathan nathan   8996 Mar 23 11:57 tiger_main-img4.jpg -rw-rw-r-- 1 nathan nathan    275 Jul 31  2014 Vanquis-benefits-icons_iphone-green.gif -rw-rw-r-- 1 nathan nathan   1821 Jul  9  2014 white-arrow-green.gif   Doing chmod 777 and then delete does not work.  Doing rm -rf * inside the directory does not work.  Doing sudo rm file does work.   I can easily remove these files using sudo, however, I cannot see why they cannot be removed without sudo. As a relatively new Ubuntu user, I would like to learn why.  Thanks in advance, Nathan


I downlad characters,but I don't know how to connect the texture to the bsdf shader help Me Modeling file

I created some texture maps in MindTex to use in Blender, but I can't figure out how to properly hook them up. The maps I have:  - Diffuse  - Normal  - Height   - Specular   - Gloss   - Self Illumination  - Reflection  - Ambient Occlusion   MindTex (left) vs. Blender (right)  As you can clearly see it's a pretty big difference.  is my material node setup in Blender. In the examples I don't actually use self illumination or reflection images, but including this in the answer would be helpful.


when I go to click 'Open in browser' on a question, it crashes in the glorious fashion of old. I wouldn't mind- but it doesn't open the question in chrome. Got any insight on this, guys?

This is a follow-up to .     When I click a link to an SE site in the Android app, it gives me an "open with" pop-up that has two options:         Chrome   Stack Exchange         I can then choose to open SE posts like this "Just once" or "Always."      The problem is that when I set the SE app to "always," and I click "open in browser,"   Except, the app crashes when trying to open it in browser.  LogCat (just right after selecting "Open in browser")  01-22 18:03:36.354: E/AndroidRuntime(16064): FATAL EXCEPTION: main 01-22 18:03:36.354: E/AndroidRuntime(16064): Process: com.stackexchange.marvin, PID: 16064 01-22 18:03:36.354: E/AndroidRuntime(16064): java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference 01-22 18:03:36.354: E/AndroidRuntime(16064):    at com.stackexchange.marvin.utils.Helpers.getNonMarvinViewIntent(Helpers.java:452) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at com.stackexchange.marvin.ui.question.QuestionDialog$1.onClick(QuestionDialog.java:39) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:1108) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.widget.AdapterView.performItemClick(AdapterView.java:310) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.widget.AbsListView.performItemClick(AbsListView.java:1145) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.widget.AbsListView$PerformClick.run(AbsListView.java:3066) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.widget.AbsListView$3.run(AbsListView.java:3903) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.os.Handler.handleCallback(Handler.java:739) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.os.Handler.dispatchMessage(Handler.java:95) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.os.Looper.loop(Looper.java:148) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at android.app.ActivityThread.main(ActivityThread.java:5417) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at java.lang.reflect.Method.invoke(Native Method) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 01-22 18:03:36.354: E/AndroidRuntime(16064):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)   I suspect it's related to , but not sure.  Specs:   Device model: Nexus 5 Android version: Android 6.0.1 SE app version: 1.0.82 (beta) Installed browser: Chrome 47.0.2526.83 (latest at current writing)


Behind the open door are hidden several differences.  This seems to be an inversion of the sentence  Several differences are hidden behind the open door.  Both sound intuitively correct, but the former inverted sentence does not fit the general inversion pattern of 'adverbial phrase + verb + subject', since it also contains the complement, 'hidden'. Is there an inversion sentence pattern that I'm missing? Or is the former sentence just plain wrong?

I understand inversion but I have a difficulty when it comes down to "there."  A: Under the window there stood a vase. B: Under the window stood a vase.  Here my teacher said that option B is correct.  C: Under the window there was a vase. D: Under the window was a vase.  And here he said that option A is correct.  Could someone explain why I can't say option D?


SOLVED: The error cause was the way I was declaring output var, please see the code  I am trying to create a regex to get the URL from a VSTS attachment in order to sync it with Jira. I tried to create a Run Javascript block with the following input:  Input Data  comment:  creationDate: 2017-10-11T11:31:19.293Z lastModifiedDate: 2017-08-29T12:32:51.393Z location: https://project.visualstudio.com/_apis/wit/attachments/ca6206de-0fab-451a-b0bc-89e70221dfcb name: Capture.PNG resourceId: 2255679   What I want to retrieve is the "location", so I thought that this would make the trick:  var regEx = new RegExp('location: (.*)', 'g'); // As mentioned in the comments, the 'g' part is not needed var path = regEx.exec(inputData); // output = path[1]; This was failing miserably var output = [{'path': path[1], 'hello': 'world'}] //This works just fine, I guess the hello world part is not really needed :)   But I always get an error:  TypeError: Cannot read property '0' of null   I have tried to create a simple javascript test to run the same and it works just fine. Can you please help me?

I want to match a portion of a string using a  and then access that parenthesized substring:  var myString = "something format_abc"; // I want "abc"  var arr = /(?:^|\s)format_(.*?)(?:\s|$)/.exec(myString);  console.log(arr);     // Prints: [" format_abc", "abc"] .. so far so good. console.log(arr[1]);  // Prints: undefined  (???) console.log(arr[0]);  // Prints: format_undefined (!!!)   What am I doing wrong?    I've discovered that there was nothing wrong with the regular expression code above: the actual string which I was testing against was this:  "date format_%A"   Reporting that "%A" is undefined seems a very strange behaviour, but it is not directly related to this question, so I've opened a new one, .    The issue was that console.log takes its parameters like a printf statement, and since the string I was logging ("%A") had a special value, it was trying to find the value of the next parameter.


So First off .Thank You everyone for the enormous help that you all have given me. Any problem i had i would always come digging here. Now i have a common dual boot system. Ubuntu & Windows . What i want to do is . I want to remove windows properly.(Not just deleting the partition ) I have the grub Boot Loader. I want to do it properly so that windows doesnt show up on Grub. So i might need to modify something in Grub. The reason im trying to open a question because i couldn't find one like this. All i get is how to remove grub or ubuntu. Not the one i want.

I used to have Windows 8.1 - Linux Mint dual boot. I succesfully removed Windows from the system but Grub still shows Windows in boot options:    I would like to configure the system the way, that on start up I directly load into Linux Mint without seeing Grub screen options at all.  What I tried so far:   sudo update-grub sudo sed -i 's/GRUB_TIMEOUT=10/GRUB_TIMEOUT=0/' /etc/default/grub  sudo update-grub Deleted Windows entry using  efibootmgr; it was entry Boot0003, it is no more there:  BootCurrent: 0002   Timeout: 0 seconds   BootOrder: 0002,0004,2003,2001,2002   Boot0000* EFI Network 0 for IPv6 (70-54-D2-8C-E9-B5)    Boot0001* EFI Network 0 for IPv4 (70-54-D2-8C-E9-B5)    Boot0002* ubuntu   Boot0004* Ubuntu   Boot2001* EFI USB Device   Boot2002* EFI DVD/CDROM   Boot2003* EFI Network    3 followed by deleting directory Microsoft from /boot/efi/EFI. Currently /boot/efi/EFI has three dirs left: Boot  toshiba  ubuntu   Is there anything else I could do?


I have Ubuntu 20.10 installed and today I decided to install Fedora in one of my HDD partition. Installation failed but Error for grub came out. Now I can't boot into Ubuntu. How to recover Grub from my Fedora Live usb stick for Ubuntu to boot

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


I need a way to rename Guest Session in login screen and make it Students, or create a guest account whit the same behavior, somebody can help me?

Now, looking around on Google shows me some ways in which to customise the settings of the Guest session. But, I would love a way to change the name of the Guest account.  Basically, I'm planning to take some laptops out to a school in Africa and want to rename the "Guest" account in 14.04 to "Student" so the students use that. They tend to store stuff on USB sticks and they're using the Guest account so they can't break anything. EDIT: I'll expand on this slightly. They're using the guest account simply for the reason it doesn't save anything after logoff. This was a specific thing the teachers have asked for.  I don't mind if the actual username remains guest behind the scenes, but as long as it shows up as Student to on Unity. Any way of going about this?


In Walter Rudin's Principles of Mathematical Analysis he defines open set as: "E is open if every point of E is an interior point of E." So this can be translated in logic as "If every point of E is an interior point of E, then E is open."  But does this mean that "If E is open, then every point of E is an interior point of E?" How is one sure when encountering these definitions that the converse also applies?

In some books the word "if" is used in definitions and it is not clear if they actually mean "iff" (i.e "if and only if"). I'd like to know if in mathematical literature in general "if" in definitions means "iff".  For example I am reading "Essential topology" and the following definition is written:     In a topological space $T$, a collection $B$ of open subsets of $T$ is said   to form a basis for the topology on $T$ if every open subset of $T$ can be written as a union of sets in $B$.   Should I assume the converse in such a case? Should I assume that given a basis $B$ for a topological space, every open set can be written as a union of sets in $B$?  This is just an example, I am not asking specifically about this sentence.


Are electrons of any conductor really  free ? I mean are they always already moving or do they move only when electrostatic field of some sort is applied across them. I suppose if they were always moving each and every conductor must have some varying magnetic field around it at all times which though negligible musy be detected. Is that really so ? Or are the so called free electrons not really free ?  Also is there some other experiment which i do not know about by which we have already proven that they are always moving ? does it take into account the earths and other electric fields which may be causing that movement ?  Addendum : the question is not duplicate of  as that post talks about ease of electrons to interact with external fields, my question is about the nature of motion of electrons in absense of external field interference as in are electrons in free motion even when they are not under the influence of any electromagnetic field.

Is it an accurate statement to say that free electrons in a metal experience NO restoring force when they interact with electromagnetic waves? I understand that the electrons exist in a space filled with ions, and doesn't the cumulative potential that is present due to the presence of the ions exert an electric field on the electrons. Even in the case of simple metals, where you can say that the nucleus is shielded by the valence electrons, so called Coulomb shielding, how significant is the shielding. Naively, it seems to me that because the charge in the nucleus is not balanced by the charge in the bound electrons, there should be some net potential that the free electron sees.


I have a layer with many points on a country, for example, Peru, and I have done a grid grouping all the country. Each hole of the grid has an ID so it's easy to differentiate them. My idea is to set that ID for each point from the other layer that way I can work with all the point on the same hole. In SQL it would be to make a new column called 'ID_Hole' and write the grid ID, but I'm not getting it on QGIS.  Any idea about what should I do?  I attach a more explicative image  The point is obtained from a.csv where I can see the name of the settlement(city) and its located by latitude and longitude on the map.

I have gridded depth points in CSV format that I'm trying to add other map data to, in additional columns. I've tried joining fields, hoping that I could link the Shapefile data to the csv, but when I try to display the csv by graduated symbols based on the new fields, it goes blank. I used Nathan's tips from , but imported the csv as csv since I want to add map info to that, rather than adding csv info to a map.  See this picture below for the sea bottom temperature & salinity voronois by month, underneath the csv points (a sample subset), with the joins already made. I added columns on the csv for each of the fields i'm intending to append.    I also tried spatial joins as per  however it says the layers aren't the same CRS (I checked, they are), then gets to 15% and hangs.  I also also tried spatial join through  but it hit a python error. I can try this again and look to debug the problem if this is the right way to go.  In short: appending polygon data as fields on a points-grid csv: what's the best way in QGIS 2.0?


I work in/at an investment firm.   Is there any difference between using in and at in this sentence?

I would like to know what usually follows after each proposition in sentences with the word "work". These are what I understand so far: I work for my boss. ( usually for certain person ) I work in a accounting corporation. (usually for business area ) I work at Samsung. ( usually for specific name of company ) Could you please tell me if I understand rightly?


I want to make my circuit board very small. I have seen many smaller boards with complex circuit. But I am not sure how do they do it? Is it all Custom circuit implemented on VHDL or some micro controller core printed on circuit board like the Black portion on the image below. I am new to PCB designing. Any suggestion would be appreciated.

In low-cost mass-produced items I often run into black blobs of what looks like resin applied directly on top of something on the PCB. What are these things exactly? I suspect this is some kind of custom IC that is layed out directly on the PCB to save on the plastic  housing/connector pins. Is this correct? If so, what is this technique called?    This is a photograph of the inside of a cheap digital multimeter. The black blob is the only non-basic piece of circuitry present, along with an op-amp (top) and a single bipolar junction transistor.


Is it "walk quickly" or "quickly walk?"  What is the correct way to phrase the sentence:  Please walk quickly.  Please quickly walk.  Thank you.

For example:     The word rarely turns up outside of those contexts.      The word turns up rarely outside of those contexts.   Which one is correct and why?


I have an account xyz and I need to calculate the sum of all related opporunities of this account and if the amount is less than 2000 rating should come '1' , if its less than 3000 rating should be '2' and less than 5000 rating should be '3'.. I am trying this way..  trigger OppoSum on Opportunity (after insert,after update)  {     Set<Id> accIdSet = new Set<Id>();      List<opportunity> oppList = new List<opportunity>();     for(opportunity o : trigger.new)     {         accIdSet.add(o.accountId);     }      map<Id,Account> mapAcc = new map<Id,Account>([Select id, name,                                                          (Select id From Opportunities)                                                     From Account Where Id IN : accIdSet]);      for(opportunity o : trigger.new)     {         Account acc = new Account();         acc.Id = mapAcc.get(o.accountId).id;         for(integer i =0;i<acc.opportunities.size();i++)         {             acc.Oppo_Amount__c = Oppo_Amount__c + o.amount;         }         if(acc.Oppo_Amount__c<2000)         {             acc.rating = '1';         }         else if(acc.Oppo_Amount__c<3000)         {             acc.rating = '2';         }         else(acc.Oppo_Amount__c<5000)         {             acc.rating = '3';         }     } }

I am not able to sum all the opportunities under the account ?  How will I do that?  What I have to use in this to run the trigger? Is it possible to create because opp. is child and account is parent ?  trigger sumAllopptyAmtAccount on Account(before insert) {     Set < ID > AccID = New Set < ID > ();     if (Trigger.isInsert)         for (Account oppAc: trigger.New) {             AccID.add(oppAc.AccountID);         }     List < Account > acc = [select id, SumAll_Opprty__c from Account where id in: a.AccID];     List < Opportunity > opp = [selece id from Opportunity where AccountID in: a.AccID];     for (Account a: acc) {         a.SumAll_Opprty__c = con.size();     } }


I am a bit confused about the release schedule of Ubuntu. AFAIK, it releases a new version every 6 months right? How about the LTS version?

I want to know where I can find updated information about all the stable and in-development versions of Ubuntu, where I can find this information?     This question is meant to be a canonical question. It expects to answer the following questions:         Is X version stable yet?   Is X version in beta?   Is X version still supported?   What versions are still supported?   What are the versions in Beta/Alpha?   Until where X version will be supported?   Have X version ceased support?   When will be X version released?   Where I can download any release?   When will the next LTS version of Ubuntu be released?         The list is not exhaustive.


I am writting a paper in IEEE format. For one sentence, i have two references and therefore i want to show them in a bracket e.g. ([1], [2]) but i am not able to get that format.  Instead of ([1], [2]) , i am getting ( [1], [2]).  So, how can i remove the extra space between "(" and first "[" as depicted in the screenshot below.   My code:  Main.tex  \documentclass[12pt,ieeeconf]{IEEEtran}  \usepackage{lipsum} \usepackage{fancyhdr} \pagestyle{fancy} \usepackage{gensymb} \usepackage{cite}  \usepackage[cmex10]{amsmath} \usepackage{graphicx} \usepackage[caption=false,font=footnotesize]{subfig} \graphicspath{{../pdf/}{/home/xyz/Desktop/rightwards}} \usepackage{epstopdf}  \usepackage{url} %\usepackage{subfigure} \usepackage{url} \usepackage{amssymb} \usepackage{amsfonts} \usepackage[all,graph]{xy} \usepackage{booktabs} \usepackage{multirow} \usepackage{array} \usepackage{comment} \usepackage{tabularx}  \title{Effect of the Position} \author {\IEEEauthorblockN{Xyz}\\ \IEEEauthorblockA{Lab, Faculty of Electrical Engineering \\ University of ABC\\ xyz@mail.de} } \markboth{Engineering Paper}{}  \begin{document} \maketitle  \input{introduction}  \bibliography{refer.bib} \bibliographystyle{plain}  \end{document}   introduction.tex  this is introduction of a paper (\cite{firstPaper}, \cite{secondPaper}).

I don't want to have a space between my bracket and the default square bracket generate by the package cite. When I write:  (\cite{ref1,ref2})   the result is:     ( [1], [2])   instead of     ([1], [2])   How can I do to remove this space please?


I have a file name (including an extension, but not a full path name) in variable file, and I want to only get the last 10 characters of the base name from a parameter expansion.  Example: file contains the filename A_text_document_1234567890.txt.  Desired output: 1234567890.  I know that I can use ${file%.*} to remove the extension: echo ${file%.*} outputs A_text_document_1234567890.  If I do base=${file%.*}, then I can use ${base: -10} to get 1234567890.  Can I do this inside the parameter expansion all in one step without using a second variable?  I guess my real question is, how do I combine these two parameter expansions into one?

I'm trying to use the Bash parameter expansions to modify the output of a command substitution or another parameter expansion. The following nested expansions work quite well in Zsh; but result in a "bad substitution" error in Bash: ${${PWD##*/}//trunk/latest}  or ${$(basename $PWD)//trunk/latest}  the output should be the last folder of the $PWD, replaced by latest when my current directory is trunk so /home/user/trunk should become latest Is there a Bash equivalent allowing to chain expansions without relying on variables or pipes? Or do Bash expansions only allows the input to be a string or a plain variable?


I have multiple date's for example(25-12-2017) i need them to be converted to milliseconds by javascript

Something similar to Unix's timestamp, that is a single number that represents the current time and date. Either as a number or a string.


I was peacefully reading the Gaming.SE blog, when suddenly, GASP I . I diligently look for a way to get rid of it... but found none. , so I'm doing a feature request. Ah, also, if someone is kind enough to remove that spam, thanks! D:

Is there a way to flag spam comments, or other OT comments on a Stack Exchange blog? Is there a way for blogs associated to Stack Exchange 2.0 sites? I just noticed the last two comments on : One seems a tentative of spamming (without any links), and the other is an OT comment about vacation.


so the house already has some ethernet wall sockets which I believe were installed when 100Mbps was more common. The cable current in used seemed to indicate that's it's not gigabit capable. I want to rewire it to CAT6. Do I need to change the sockets as well?  I looked at eBay at several wall sockets supposedly designed for CAT6 but I can't see any difference to my untrained eye.  Thank you for the help. :)

I was wondering if I can use a CAT5e keystone jack with CAT6 cable. I am refering to the parts that terminate a cable where it comes out of the wall.  I want to run a 30 ft length of CAT6 but all I have is CAT5e jacks and I don't want to buy any news ones if I don't have to.  I had read somewhere that CAT5e is 100mhz and CAT6 is 200mhz (though I could have sworn CAT6 was 350mhz).  Anyhow any assistance would be appreciated.


Just noticed a minor css issue on this question:    The related questions on the right hand side have some overlapping text in Chrome:        (This only applies to this very site, Meta Stack Exchange)

I just observed related questions  contained a post that has a score higher than 999, causing it to look different from the others:        I think it should be consistent.  As per , either it should show 1k or it should look something like:        The post is marked as status-completed but it still appearing not fixed to me:


I'm using the Boruta package in R to select the best variables used then for my predictive model. Then I plotted the results from cross validation but I don't understand its meaning.    How can I Interpret this plot?

I am running the classify in Weka for a certain dataset and I've noticed that if I'm trying to predict a nominal value the output specifically shows the correctly and incorrectly predicted values. However, now I'm running it for a numerical attribute and the output is:  Correlation coefficient                 0.3305 Mean absolute error                     11.6268 Root mean squared error                 46.8547 Relative absolute error                 89.2645 % Root relative squared error             94.3886 % Total Number of Instances               36441    How do I interpret this? I've tried googling each notion but I don't understand much since statistics is not at all in my field of expertise. I would greatly appreciate an ELI5 type of answer in terms of statistics.


Is it possible to produce a 100% confidence interval for a sample mean?  Or does a 100% confidence interval imply that it is no longer a sample mean; that the population mean is already known?

Is it possible to apply the law of the iterated logarithm (e.g. ) to derive non-trivial (i.e. bounded) 100% confidence intervals for population averages?  An abstract () gives at least such hint. However, its first reference by Robbins () does not seem to cover such result, as pointed out in @whuber's comment.  Edit: After justified comments by @whuber, I reformulated the question.


some years ago (2007) I have published a  paper in a conference as a poster paper. Now I want to send it to a journal and change the affiliation, or maybe some minor changes. I didn't see any policy about a previous published paper in a conference, however there is a policy as the following:     The submission has not been previously published, nor is it before   another journal for consideration (or an explanation has been provided   in Comments to the Editor).   Could I send my paper to this journal?   Is it a normal thing to first publish a paper in  a conference and then trying to send it to a journal?

For conferences that "peer review" and "publish" full papers, when, if ever, can you resubmit essentially unchanged versions for publication in a peer reviewed journal?  In my field, when conference papers appear as book chapters, people often "republish" them as journal articles.  I have just had a talk accepted at a conference which is now (decided post submission) planning on publishing the proceedings as a special issue of a journal. It appears the journal is complete crap with an extremely light peer review process in general, no impact factor, and essentially not indexed. I think this "article" will be worthless, but I am concerned that I will not be able to republish the results in a respectable journal.


I want to update my ubuntu on my desktop.  I cant use usb too boot as it have old BIOS.  It can boot from cd but then ubuntu needs 1,1 GB so cd will not work.  my desktop also cant boot from DVD .. Old bios.  I have .iso file on my computer. Is it any way i can install/ upgrade ubuntu?

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


I build a static page in my WordPress root folder. Now I'm trying to include a list of my categories with echo clpr_categories_list();.  Its not working because I some how have to tell the static page where to find my theme. How do I do this? Searched everywhere.

I read about 2 methods for initializing WordPress function outside of WordPress files so We can use these functions on any page or website outside the WordPress blog.  Which one of these 2 methods is the correct one? What are the use cases for each method if both are correct? What is the deference between using one method or the other?  Method 1:  <?php      define('WP_USE_THEMES', false);     require('./wp-blog-header.php'); ?>   Method 2:  <?php      define('WP_USE_THEMES', false);     require('./wp-load.php'); ?>


Let $k \in N$ and $a_1, a_2, ..., a_k > 0$. Prove that the following series $(b_n)$ converges and define its limit.  $$b_n := \sqrt[n]{\sum_{i = 1}^ka_i^n}$$  I'm quite sure it converges to something between $min(a_i)$ and $max(a_i)$, but don't really know where to start. Sandwich theorem wasn't of much help as well.  Thanks in advance!

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


A recent scandal has been making waves in social media - a United Air passenger was forcibly dragged off of the flight after refusing compensation due to overbooking of the flight.    Ignoring the moral implications, and any air regulations United itself may have, do airlines have the legal right to treat a passenger on an overbooked flight in this manner?

I was recently surprised to see  because his flight was overbooked.  He was reportedly a doctor who needed to see patients the next morning, so he did not really want to get off, justifying the use of force.  I knew that airlines could overbook flights and deny boarding to some passengers, but I thought that kind of boarding denial would happen at the gate and that once folks had been let on, those denied boarding would be those arriving later to the gate.    Why or in what conditions is this kind of forcible removal considered OK?    Clarification following close votes from people who think this question is primarily opinion-based: By "OK" I mean the sense of "legally OK," "officially accepted," "instantiated as policy," "sanctioned by authorities," or "OK according to the regulations and policies and laws and whatever other formal rules govern forced removal from flights due to overbooking." Whether or not you personally consider it socially acceptable does not matter as an answer, unless you have formalized that into a citeable adopted form that governs what happens and want to explain the reasoning behind that rule.


Prove $\|x\|\le\sum_{i=1}^n|x_i|\le\sqrt{n}\|x\|$ for all $x\in\mathbb{R}^n$.  I'm stumped, can't find any intuition here or where to begin. Any suggestions?

Prove   $$\|x\|_2 \le  \|x\|_1 \le \sqrt n\|x\|_2. \forall x \in \mathbb{R}^n$$  I already proved the first inequality $\|x\|_2 \le \|x\|_1$. Please help me with the second part:  $$\|x\|_1\le \sqrt n \|x\|_2.$$


I needed to add some libraries from git but when I tried updating it showed the following error "E: Malformed line 3 in source list /etc/apt/sources.list.d/google-earth-pro.list (type) E: The list of sources could not be read." I don't know if any previous update made any change to that file or what but I cannot use "apt-get" in ubuntu 16.04.

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


I want to download packages from the Ubuntu archive without fully installing them. The default sudo apt install downloads and installs them. I only want to download them. Is this possible?

I know that when it comes to the Red Hat distribution, I can use the following commands to download a copy of the package and then separately install it. yumdownloader package_name yum install package_name  Is there an exact equivalent in Ubuntu that does both the operations separately, or does the following command do both? apt-get install package_name


I get this error in Lubuntu 12.04 when I try to update in terminal:  $ apt-get update E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied) E: Unable to lock directory /var/lib/apt/lists/ E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?

I get this error whenever I try to install programs using the terminal:  home@ubuntu:~$ apt-get install myunity E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   Also I'm unable to install updates using the terminal.


I have this trigger   CREATE TRIGGER [dbo].[intrigger] ON [dbo].[test]  instead of insert AS begin declare @name nvarchar (50),@city nvarchar (11), @tdate datetime , @fid int,@fopd datetime; select @name =i.name from inserted i; select @city =i.city from inserted i; select @tdate =i.date from inserted i; select @fid =i.fid from inserted i; select @fopd = Faculty.fopd from Faculty      where fid= @fid; if (@fopd > @tdate ) begin     RAISERROR('Cannot insert ',16,1);     ROLLBACK TRANSACTION     RETURN;     -- stop on error end insert into test values (@name,@city,@tdate,@fid);  end   and the insert :  insert into test values('a','h','2014-10-13',1), ('s','h','2014-10-14',2), ('y','d','2014-10-15',2), ('s','h','2014-10-18',1), ('m','a','2014-10-20',1), ('a','h','2014-10-28',2)   then I select * from test .. only the last values are inserted ('a','h','2014-10-28',2)  I have to do one insert at a time !   I used for trigger .. all lines were inserted BUT in another test it accepted the wrong values :  insert into test values('a','h','2014-10-13',1), ('s','h','2014-10-14',2), ('y','d','2014-10-15',2), ('s','h','1990-10-18',1), -- this is wrong must not be inserted or stop all  ('m','a','2014-10-20',1), ('a','h','2014-10-28',2)   what went wrong !?

In SQL Server 2012,    I create two tables TABLE1 and TABLE2 After that, I created a trigger for TABLE1 Trigger name: PUSH_TABLE2  SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO  CREATE TRIGGER [dbo].[PUSH_TABLE2]     ON [dbo].[TABLE1]     AFTER INSERT AS BEGIN     DECLARE @col1 VARCHAR(20), @col2 VARCHAR(20), @col3 VARCHAR(20)     SELECT @col1=column1, @col2=column2, @col3=column3 FROM INSERTED      SET NOCOUNT ON;      INSERT INTO [dbo].[TABLE2] VALUES (@col1, @col2, @col3);  END  After creating the trigger PUSH_TABLE2, I test with below insert query manually on TABLE1, triggers works perfectly and its populate the data to both TABLE1 and TABLE2.  INSERT INTO TABLE1 VALUES('session1', 'value1', 'type1');  (1) rows affected.  (1) rows affected.    The problem is if the data is populated through application, it will only populate the data to TABLE1 only, seems trigger is not working. Is it because of my trigger script problem?


I’m very new to Linux and can’t really use the command line well. I’m simply trying to install the latest updates. When I do, I get a ‘not enough free space’ message.  I can see in my System Monitor that my boot drive is pretty much full, but the internal 1 terabyte HDD has barely been touched. Is my boot drive a different storage unit in my computer I don’t know about (perhaps something that comes default on the motherboard)?  Is there a way to change my boot drive smoothly to the terabyte HDD? That is, can I easily transfer the OS files to that drive? In fact, what is the boot drive? Is it simply whatever drive I have the Linux OS on?    I’ve done some looking around on forums and see that people clear out old kernels. I don’t quite understand what this means. Are they simply deleting the old updates, because the newer ones have essentially more efficient and better programming/capabilities?  Is there a way to do this without using the command line?  What is the best solution?

My /boot partition is nearly full and I get a warning every time I reboot my system. I already deleted old kernel packages (linux-headers...), actually I did that to install a newer kernel version that came with the automatic updates.  After installing that new version, the partition is nearly full again. So what else can I delete? Are there some other files associated to the old kernel images?  Here is a list of files that are on my /boot partition:  :~$ ls /boot/ abi-2.6.31-21-generic         lost+found abi-2.6.32-25-generic         memtest86+.bin abi-2.6.38-10-generic         memtest86+_multiboot.bin abi-2.6.38-11-generic         System.map-2.6.31-21-generic abi-2.6.38-12-generic         System.map-2.6.32-25-generic abi-2.6.38-8-generic          System.map-2.6.38-10-generic abi-3.0.0-12-generic          System.map-2.6.38-11-generic abi-3.0.0-13-generic          System.map-2.6.38-12-generic abi-3.0.0-14-generic          System.map-2.6.38-8-generic boot                          System.map-3.0.0-12-generic config-2.6.31-21-generic      System.map-3.0.0-13-generic config-2.6.32-25-generic      System.map-3.0.0-14-generic config-2.6.38-10-generic      vmcoreinfo-2.6.31-21-generic config-2.6.38-11-generic      vmcoreinfo-2.6.32-25-generic config-2.6.38-12-generic      vmcoreinfo-2.6.38-10-generic config-2.6.38-8-generic       vmcoreinfo-2.6.38-11-generic config-3.0.0-12-generic       vmcoreinfo-2.6.38-12-generic config-3.0.0-13-generic       vmcoreinfo-2.6.38-8-generic config-3.0.0-14-generic       vmcoreinfo-3.0.0-12-generic extlinux                      vmcoreinfo-3.0.0-13-generic grub                          vmcoreinfo-3.0.0-14-generic initrd.img-2.6.31-21-generic  vmlinuz-2.6.31-21-generic initrd.img-2.6.32-25-generic  vmlinuz-2.6.32-25-generic initrd.img-2.6.38-10-generic  vmlinuz-2.6.38-10-generic initrd.img-2.6.38-11-generic  vmlinuz-2.6.38-11-generic initrd.img-2.6.38-12-generic  vmlinuz-2.6.38-12-generic initrd.img-2.6.38-8-generic   vmlinuz-2.6.38-8-generic initrd.img-3.0.0-12-generic   vmlinuz-3.0.0-12-generic initrd.img-3.0.0-13-generic   vmlinuz-3.0.0-13-generic initrd.img-3.0.0-14-generic   vmlinuz-3.0.0-14-generic   Currently, I'm using the 3.0.0-14-generic kernel.


Which is the fastest search method in linux to search (only) for a text inside whole linux file system (NOT JUST A SINGLE FILE) the search needs to be performed on all the files including the root binaries.

Which is more efficient for finding which files in an entire filesystem contain a string: recursive grep or find with grep in an exec statement?  I assume find would be more efficient because you can at least do some filtering if you know the file extension or a regex that matches the file name, but when you only know -type f which is better? GNU grep 2.6.3; find (GNU findutils) 4.4.2  Example:  grep -r -i 'the brown dog' /  find / -type f -exec grep -i 'the brown dog' {} \;


As we know, the shell enables the user to run background processes using & at the command line's end. Each background process is identified by a job ID and, of course, by it's PID.  When I'm executing a new job, the output is something like [1] 1234 (the second number is the process ID). Trying to invoke commands like stop 1 and stop %1 causes a failure message: stop: Unknown job: 1  Understanding that the stop command causes a job to be suspended, I was wondering how to get the job ID and do it right. If the only way to kill a job is by it's process ID, what is the purpose of the job ID?

I accidentally "stopped" my telnet process.  Now I can neither "switch back" into it, nor can I kill it (it won't respond to kill 92929, where 92929 is the processid.)  So, my question is, if you have a stopped process on linux command line, how do you switch back into it, or kill it, without having to resort to kill -9?


This is the 3rd question from the 2nd chapter of the book "A Walk Through Combinatorics - Miklos Bona"  The question is as follows -  At a tennis tournament, there were $2^n$ participants, and any two of them played against each other exactly one time. Prove that we can find $n+1$ players that can form a line in which everybody has defeated all the players who are behind him in the line.  The proof stated is as follows -   "Induction on $n$. For $n = 1$, the statement is trivially true. Now assume the statement is true for n and prove it for $n + 1$. The winner $X$ of a tournament with $2^{n+1}$ participants must have won at least $2^n$ games (why?). Take $X$, and $2^n$ people he defeated. By the induction hypothesis, we can find $n + 1$ people among the $2^n$ people defeated by $X$ who can form a line with the required property. Then we put $X$ to the front of this line and we have obtained a line of length $n + 2$ that has the required property."  My problem with this -   The winner in a tournament with $2^{n+1}$ players has at least $2^n$ as proven here by @Martund -    But the winner $X$ may have more than $2^n$ wins, in which case we may not find a set of $2^n$ players who lost to $X$ for us to apply induction and extract the line of $n$ players? How do we fix this?

At a tennis tournament, there were $2^n$ participants, and any two of them played against each other exactly one time. Prove that we can find $n+1$ players that can form a line in which everybody has defeated all the players who are behind him in the line.   How would you prove this by induction? Also what does it mean to form a line? Thanks


I really hope that someone has the time to help out a complete newb regarding blender.  I hava a collada terrain thats been exported from QGIS. When exporting the terrain i get two files with the same name; one .dae (collada model) and one .png (texture).  I can import the collada file inte blender fine, but i really cant wrap my head around the texture file. When I export it i have a nice texturized terrain 3D modell (arial photo). In blender I get the bland collada file without any texture. I've tried looking at few dozen tutorials and forums, tried with materials, textures and shrinkwrap (in blender) but without any better results than getting the collade texturized with hundreds of miniversions of my picture.  Can anybody please explain how to get my arial photo on my terrain? Or at least point me in the right direction.  I would be extremely greatful since I'm starting to feel like a complete tech idiot (and I'm a GIS engineer :)  I've tried exporting to wawvefront and stl and importing in blender with the same results.

I used node textures in a mesh I exported to .FBX.  I then imported it into Unreal Engine 4 and it didn't import any textures; I clicked the Upload Textures option in Unreal Engine.  Is there something I'm doing wrong or is it Blender?


Can I ask questions about software application recommendations anywhere in the stackexchange system?  For example, I have a requirement, which will involve software and hardware.  I want to type this requirement up somewhere where possible readers will be able to recommend hardware and software solutions to my requirements?

I have a list of requirements for a program, but I don't know what program meets these criteria. That's about general-purpose software, for example, not a programming IDE or statistical workbench, questions about which would certainly go to respective sites.  Is this question appropriate on Stack Overflow? Where should I ask about it? On Super User or elsewhere?


I have a very basic question regarding confidence intervals. I am confused between two interpretations of confidence intervals.  Interpretation 1:  If repeated samples were taken and the 95% confidence interval computed for each sample, 95% of the intervals would contain the population mean.5% of the intervals would not contain the population mean  Interpretation 2: If we were to take 100 additional samples, 95 times out of 100, the population mean rate would fall between 2.5% and 17.5%.   Which of these would be correct?

I know roughly and informally what a confidence interval is.  However, I can't seem to wrap my head around one rather important detail:  According to Wikipedia:     A confidence interval does not predict that the true value of the parameter has a particular probability of being in the confidence interval given the data actually obtained.     I've also seen similar points made in several places on this site.  A more correct definition, also from Wikipedia, is:     if confidence intervals are constructed across many separate data analyses of repeated (and possibly different) experiments, the proportion of such intervals that contain the true value of the parameter will approximately match the confidence level   Again, I've seen similar points made in several places on this site.  I don't get it.  If, under repeated experiments, the fraction of computed confidence intervals that contain the true parameter $\theta$ is $(1 - \alpha)$, then how can the probability that $\theta$ is in the confidence interval computed for the actual experiment be anything other than $(1 - \alpha)$?  I'm looking for the following in an answer:   Clarification of the distinction between the incorrect and correct definitions above. A formal, precise definition of a confidence interval that clearly shows why the first definition is wrong. A concrete example of a case where the first definition is spectacularly wrong, even if the underlying model is correct.


I tried installing opendjk-7 in the way that was suggested , but I get this error:  W: The repository 'http://ppa.launchpad.net/openjdk-r/ppa/ubuntu yakkety Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. E: Failed to fetch http://ppa.launchpad.net/openjdk-r/ppa/ubuntu/dists/yakkety/main/binary-i386/Packages  404  Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.

I would like to upgrade my main system to 16.04, but I work on projects that require OpenJDK 7.   Apparently it is not available from a trivial apt-get install openjdk-7-jdk. Only versions 8 and 9 are listed in the repository.  Can anyone point me to instructions on how to install it?


If $A \subseteq X$ and $A_{\alpha}$ is a collection of all such subsets, I need to prove that:  $$\left(\bigcap_{\text{all }\alpha} A_\alpha\right)^c = \bigcup_{\text{all }\alpha} A_{\alpha}^c$$  My attempt:  $$\text{Step 1: }A^c = \{ x : x \in X, x \not \in A \}$$ So, $$\text{Step 2: } \left(\bigcap_{\text{all }\alpha} A_\alpha\right)^c =  \{ x:  x \in X, x \not \in \{x : x \in X, x \in A_1 \wedge x \in A_2 \wedge\cdots \}\}$$  $$= \{x : x \not \in A_1 \vee x \not \in A_2 \vee x \not \in A_3 \vee \cdots\}$$  Similarly,   $$\text{Step 3: } \bigcup_{\text{all }\alpha} A_\alpha^c = \{ x: x \in A_1 \wedge x \in A_2 \wedge x \in A_3 \wedge \cdots \}$$  I understand that if I want to show that $A = B$, I need to show that $A \subseteq B$ and that $B \subseteq A$.  But I'm not sure how to relate step 2 to step 3.  Also, is the direct jump from step 1 to 2 justified. Or do I need an intermediate step?

Let $X$ be a set and $\{Y_\alpha\}$ is infinite system of some subsets of $X$. Is it true that: $$\bigcup_\alpha(X\setminus Y_\alpha)=X\setminus\bigcap_\alpha Y_\alpha,$$ $$\bigcap_\alpha(X\setminus Y_\alpha)=X\setminus\bigcup_\alpha Y_\alpha.$$ (infinite DeMorgan laws)  Thanks a lot!


I wish to show that the injection $k[y^2, y^3] \rightarrow k[y]$ is not flat.    I know of geometric ways to see this, but I wish to see explicitly $k[y^2, y^3]$-modules (or localizations thereof) $0 \rightarrow M' \rightarrow M$ which does not remain injective upon tensoring with $k[y]$. Is such a search futile?

Consider $k$ a field and the rings $A=k[X^2,X^3]\subset B=k[X]$. How to prove that $B$ is not flat over $A$ by using only the definition of flatness that it maintains exact sequences after making tensor products?


I don't remember that anyone referred to her as Captain Marvel in her solo movie. Did anyone in Avengers call her Captain Marvel? If so, why? Did she introduce herself as Captain Marvel?  If not, is that mean, we don't have Captain Marvel, Captain Danvers instead?

So I'll start by saying Brie Larson's Carol Danvers is Captain Marvel and we should all call her that.  My question is though is the title diegetic? Can we expect anyone in the movies to call her that?  I don't think anyone was called by their rank in the movie and I can't tell from the uniforms but both Carol Danvers/Vers and Dr. Wendy Lawson/Mar-vell could've been a Captain in the Air Force/Starforce.  Did I miss something about Carol taking on her mentors name or something or is Captain Marvel just what we, the viewers, call the character in the real world? It didn't seem like she needed or wanted a secret identity, she could just go by Carol.


I've created a custom JtextField but any proprety defined method don't working like getText or SetText when I call it in the main JFrame.  import javax.swing.JTextField; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent;  public class JTextFieldDecimal extends JTextField {     private static final long serialVersionUID = 1L; public JTextFieldDecimal() {     super();     addKeyListener(new KeyAdapter() {         @Override         public void keyTyped(KeyEvent e) {             char c =e.getKeyChar();             if(!((c>='0') && (c<='9') ||                      (c==KeyEvent.VK_BACK_SPACE) ||                     (c==KeyEvent.VK_DELETE)))             {                 getToolkit().beep();                 e.consume();             }          }     });  } }     when I click in validation button in jframe Produit the compiler give me an error and point to line 98 wich content my statement parameter of Custom JtextField named txtPrixHT.  btnValider.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent arg0) {             Connection cn=null;             PreparedStatement pst =null;             ResultSet rs=null;             try {                 Class.forName("com.mysql.jdbc.Driver");                 cn=DriverManager.getConnection("jdbc:mysql://localhost/gesticom", "root","");                 //String sqlAdd ="insert into produit (PrCodeBarre,PrDesignation,PrPrixHT,PrRemise,PrPrixAchat,PrStockAlerte,PrStockReel) values (?,?,?,?,?,?,?)";                 String sqlAdd ="insert into produit (PrCodeBarre,PrDesignation,PrPrixHT) values (?,?,?)";                 pst=cn.prepareStatement(sqlAdd,Statement.RETURN_GENERATED_KEYS);                 pst.setString(1, txtCodebarre.getText());                 pst.setString(2, txtDesignation.getText());                 pst.setString(3,txtPrixHT.getText());                 pst.execute();                 rs=pst.getGeneratedKeys();                 if(rs.next())                 {                     txtIdprod.setText(rs.getString(1));                     JOptionPane.showMessageDialog(null, "Nouveau Produit créé", "Fournisseur",JOptionPane.INFORMATION_MESSAGE);                 }             } catch (ClassNotFoundException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             } catch (SQLException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }             finally {                 try                 {                     cn.close();                     pst.close();                 }                 catch (SQLException e)                 {                     e.printStackTrace();                 }             }             }         });

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?


****It throws NullPointerException in JOptionPane code as following.****  public static void main(String[]args){       String[] options={"Do it again?", "Exit"};     int response=0;     int indexOfZip;     do{         try{          String dataStr=JOptionPane.showInputDialog("Enter a zip code");           if(dataStr!=null){              while (k<i){                  if (place[k].equals(dataStr)){                   indexOfZip=k;                      k++;                  }               }              int data=Integer.parseInt(dataStr);              response=JOptionPane.showOptionDialog(null,                            "You asked me to search for zip code:"+dataStr+"The zip code "+dataStr+" belongs to"+place[k].getTown()+","+place[k].getState()+"Do you want me to search again?",                            "results",                             JOptionPane.YES_NO_OPTION,                            JOptionPane.QUESTION_MESSAGE,                            null,                            options,options[0]);                System.out.println("You asked me to search for zip code:"+dataStr);              System.out.println("The zip code "+dataStr+" belongs to"+place[k].getTown()+","+place[k].getState());              System.out.println("Do you want me to search again?");          }           }catch(NumberFormatException e){         JOptionPane.showMessageDialog(null,"Bad Numeric String, try again.", "Input Error",JOptionPane.ERROR_MESSAGE);           }     }while(response==0);     if (response!=0){        System.out.print("No");        System.out.println("Good Bye!");     }        }   The terminal says the exception is for this line     response=JOptionPane.showOptionDialog(null,  But I cannot see anything wrong here, because the "response" is initialized before.


I am planning to move my LAMP stack to AWS as the number of users increases. Current estimations suggest, that the Server has to handle roughly 100.000 users accessing the static landing page, out of which about 5.000 will use the internal pages (PHP and Database access). Can I use AWS to host my site and what should I pay attention to?

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


I am getting this error on my website.      Strict warning: Creating default object from empty value in theme541_preprocess_html()   I found a patch  by Damien McKenna but I don't know how to apply the patch that fixes the error.

I downloaded a patch file from mailhandler module and need to apply the changes in order to fix the problem of pop3 accounts not deleting emails after download (import).  How do I install it?


Is it less efficient to put a try-catch block inside of a loop as opposed to wrapping the loop with a try-catch in php if it is intended that the loop will end if an exception occurs? Or is there essentially no difference?  EDIT:  i.e.,  foreach (/*...*/) {     //...     try {         //...     } catch (/*...*/) {         break;     }     //... }   versus:  try {     foreach (/*...*/) {         //...     } }

What kind of performance implications are there to consider when using try-catch statements in php 5?   I've read some old and seemingly conflicting information on this subject on the web before. A lot of the framework I currently have to work with was created on php 4 and lacks many of the niceties of php 5. So, I don't have much experience myself in using try-catchs with php.


I just tried to log out of chat.SE (I'm an active user in GameDev and sometimes use other chat rooms), but I can't seem to. Could this possibly be tied to the new global-auth update? I have tried hitting "log out" in the dropdown menu, which just redirects me to . That link also does not work, just seemingly redirecting me to  and showing my active rooms (aka the site rooms for GameDev.SE). I can log out through the main GD.SE site proper, which also logs me out of chat, but upon clicking "log in" again on the chat site, I get: . Logging in on the site proper seems to again, work as expected. Some system information: Windows 8.1 Browser: Firefox 39.0

I attempted to log out with the following actions:    This accomplished absolutely nothing since I remained logged in after clicking "log out" on the confirmation page. I then tried logging out of Stack Exchange from one of the network sites and repeated the steps above. The results were the same. I remained logged in no matter which combination of steps I performed.  In fact, the only way I could log out at all was to clear all of the cookies that were set.


When I tried   pip3 install numpy    I got the error as   SystemError: Cannot compile 'Python.h'. Perhaps you need to install python-dev|python-devel.   Then I continue to install python-dev but got failed too.   I've also tried   sudo apt-get install python3-numpy   and got   The following packages have unmet dependencies:  python3-numpy : Depends: liblapack3 but it is not going to be installed or                       liblapack.so.3

Python3.4.0  on Ubuntu 14.04.01 LTS. We can use it by typing on Terminal `python3.  I want to use Numpy for Python3.4.0. I run import numpy  but I had anImportError.So sudo apt-get install python-numpy. Then I typed on Terminal:python3`. Then import numpy. I got this error:  >>> import numpy Traceback (most recent call last):   File "<stdin>", line 1, in <module> ImportError: No module named 'numpy' >>>    Nevertheless, Numpy is now working for Python-2.7:  begueradj@begueradj-Bill:~$ python Python 2.7.6 (default, Mar 22 2014, 22:59:38)  [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import numpy >>>    How can I make Numpy work for Python 3.4.0 ?


I am a first-year maths student but I occasionally drift away from our taught material. Some years ago I saw the ZFC axioms for the first time, but now that I am in college, and although the stuff I've been taught so far is nowhere near ZFC (in terms of difficulty), it happened to me that we use the axiom of choice all the time in every module, even if we don't know it by name yet.  For example, in the proof that, for every non-negative integers $a, b$, there exist integers $q, r: a = bq + r$ (with the known restrictions on r), and the proof starts like this: $Choose$ the largest integer $q : qb <= a$... blah blah blah.  Is it the axiom of choice that allows us to execute this simple yet so important step?   And a couple more questions: Can you name some other simple proofs, theorems, results etc for which the axiom of choice is essential?  Also, I've read that AOC has long been a topic of dispute for mathematicians, and that even today, some people do not accept it. Are there any alternative axiomatic systems that work equally well without needing AOC? Thanks!

I'm having trouble understanding the necessity of the Axiom of Choice. Given a set of non-empty subsets, what is the necessity of a function that picks out one element from each of those subsets? For instance, take a look at following paragraph from Wikipedia:     A sketch of the proof of Zorn's lemma follows, assuming the axiom of   choice. Suppose the lemma is false. Then there exists a partially   ordered set, or poset, P such that every totally ordered subset has an   upper bound, and every element has a bigger one. For every totally   ordered subset T we may then define a bigger element b(T), because T   has an upper bound, and that upper bound has a bigger element. To   actually define the function b, we need to employ the axiom of choice.   Using the function b, we are going to define elements a0 < a1 < a2 <   a3 < ... in P. [...]   To me it is clear that the ai's exist so why do we need singling them out? Sure enough, the binary relation representing b may not exist as a set, but what do we need it for?  Finally... if we actually need the Axiom of Choice to single out the ai's in the above paragraph, since the axiom only postulates the existence of choice functions, how do we single out the choice function itself so that we can select the ai's with it? Certainly not with another choice function, since we would need to choose this function by a third choice function.  So when and why do we really need the Axiom of Choice?


Prove that limit of sequence $x_n = {a^n \over n!}$ is $\lim_{n \to \infty} x_n = 0$   Let $\epsilon > 0$ So we need to prove: $|x_n - a| < \epsilon$  $$\implies\left|{a^n \over n!}- 0\right| < \epsilon$$ $$\implies{a^n \over n!} < \epsilon$$ $$\implies n\log{a} - \log n!< \log\epsilon$$  I don't know how can I isolate $n$ in this inequality.  Please provide hints, so that I can work the answer on my own. Thanks.   EDIT:- I think my question is not duplicate because, the answers  does not contain $\epsilon$ proof.

Why is     $$\lim_{n \to \infty} \frac{2^n}{n!}=0\text{ ?}$$   Can we generalize it to any exponent $x \in \Bbb R$? This is to say, is     $$\lim_{n \to \infty} \frac{x^n}{n!}=0\text{ ?}$$     This is being repurposed in an effort to cut down on duplicates, see here: Coping with  duplicate questions.  and here: .


How can I describe the difficulty of somebody who is trying to explain something to people who are not in his/her professional field, and is afraid of using professional terms that will be unclear to his/her listeners?   In my native language, I would say "it is hard to go out of the professional circle". How can I say it in English?  An example:       I have tried my best to explain this subject as clearly as possible, but it is hard to______   I do not think my question is a duplicate because I looked for a term expressing a difficulty of explaining. I didn't get a direct answer, so I deduced there is no such a term.

How do you ask someone to explain something in very simple words, understandable by everyone from general public? In Russia we say something, that can be translated like "explain on fingers". What's the correct English for this?


I am trying to prove that the series $\sum\limits_{n=2}^\infty \frac{\sqrt{n+1}-\sqrt{n}}{n}$ is convergent. I tried using the comparison test, but it's not showing me that the series is convergent.  These are my steps:  Using $\sum\limits_{n=2}^\infty = \frac{1}{n^{3/2}}$  $$\lim_{n\to\infty}\frac{\frac{\sqrt{n+1}-\sqrt{n}}{n}}{\frac{1}{n^{3/2}}} = \lim_{n\to\infty}(\sqrt{n})(\sqrt{n+1}-\sqrt{n})=\lim_{n\to\infty}n+\sqrt{n}-n=\sqrt{n}$$  This shows that the series in non-convergent, which I know not to be the case.

Does this series converge or diverge?  $$\sum_{n=1}^\infty\frac{\sqrt{n+1}-\sqrt{n}}{n}$$  I tried the comparsion test with $\sum_{n=1}^\infty$ $1 \over n$ but this does not help.  I also tried to simplify the series to $\sum_{n=1}^\infty \frac{1}{n (\sqrt{n+1}+\sqrt{n}{}{}{})}$ but this become harder.


Which of these sentences are using the proper usage of punctuation?  Nicolo said, "I'll let you know if anything changes." Nicolo said, "I'll let you know if anything changes". Nicolo said, "I'll let you know if anything changes.".  Or is there a certain rule when all of the sentence is correct especially when writing novels or stories.

The American convention in quotations is (typically) to place punctuation inside quoted text. But I always run into situations where the punctuation of the quote interferes with the punctuation of the sentence. How would you punctuate this (American, non technical)?     When my friends ask, "What do you want for your birthday?", I never know how to respond.   It seems odd to place the last comma outside the quote simply because of the question mark. Is that the preferred (i.e. most often accepted) standard?


I am 9 grade, My math teacher asked me to add numbers with out using + sign in C program.    I tried  a - (-b) = a + b; but my math teacher want some other option.

A friend and I are going back and forth with brain-teasers and I have no idea how to solve this one.  My assumption is that it's possible with some bitwise operators, but not sure.


I am working on PhoneGap and I need to set some Environmental variables. I used to set it by export and it sets. But when I reboot or relog then it wipes out the variables I previously exported. I don't know why its happening...  I did :   $ export PATH=${PATH}:${ANDROID_HOME}`  $ export PATH=${PATH}:${ANT_HOME}`   and similar stuff....  Please help me or provide some hints or suggestions..

Just as the title indicates my PATH variable resets after every reboot. I read that I have to edit my bashrc file's PATH variable, but I don't have anything there that suggests anything related to the PATH variable.


I use D7. My site is being hosted on a "Shared" Server at Siteground.com. My site doesn't have any CSS/JS aggregation what so ever (see attachment), and I'm sick and tired of clearing the cache after the smallest of the CSS changes.  Many people told me that installing Devel and enabling "Rebuild the theme registry on every page load" should solve the problem, and will let me see the CSS changes after a refresh (F5/ctrl+r/ctrl+f5), but the fact is that even after I did that and enabled the Theme registry rebuilding option, I still have to clear caches to see the CSS changes, so I'm still stuck with this, and it's indeed frustrating!.  So, why would "Rebuild the theme registry on every page load" won't work? Why do I still need to flush all caches to see the CSS changes?

Every time I make the slightest CSS change, I need to clear cache to see the changes.   What can be done about this?


The problem involves arranging balls of different color in a line such that no two balls of the same color are adjacent to each other. Eventually I would like to find a generalization of having $m$ different colors of balls and $n$ balls of each color, where each ball besides color are indistinguishable. But for now I will start with $3$ colors, red blue and yellow, and having $3$ of each color.  If we had an infinite number of each ball, then i know the answer would be $3(2^8)$ but this is including arrangements where we might only have red and blue balls alternating and not have any yellows.  One thought was to consider "grouping" the colors in its $3!$ permutations and finding the number of arrangements of the groups. But this wouldn't consider arrangements such as $RYRYBYBRB$  I feel like recurrence may be needed for a generalization but without being able to find this simple case I don't know if I can use it. Searching other questions of this sort doesn't help me either as it isn't this type of restriction.  Brute forcing it is one option but it seems like a mess even for this smaller case, so it would only be good for smaller cases.  Any help would be greatly appreciated

Given $n_1 $ number of  $1 $'s,  $n_2 $ number of  $2 $'s,  $n_3 $ number of  $3 $'s,  $n_4 $ number of  $4 $'s.  form a sequence using all these numbers such that two adjacent numbers should not be same.  I have tries lot of things but nothing worked.  can somebody tell me how to solve this problem?


Hi I'm new to Java programing and I am having some trouble with doubles. I am trying to subtract .2 from 4.6 but instead of receiving 4.4 i get 4.3999999999999995. I know that Decimals can't be represented exactly in binary but is there any way around this problem. Any advice would be appreciated.

What I would like is a method to convert a double to a string which rounds using the half-up method - i.e. if the decimal to be rounded is 5, it always rounds up to the next number. This is the standard method of rounding most people expect in most situations.  I also would like only significant digits to be displayed - i.e. there should not be any trailing zeroes.  I know one method of doing this is to use the String.format method:  String.format("%.5g%n", 0.912385);   returns:  0.91239   which is great, however it always displays numbers with 5 decimal places even if they are not significant:   String.format("%.5g%n", 0.912300);   returns:  0.91230   Another method is to use the DecimalFormatter:  DecimalFormat df = new DecimalFormat("#.#####"); df.format(0.912385);   returns:  0.91238   However as you can see this uses half-even rounding. That is it will round down if the previous digit is even. What I'd like is this:  0.912385 -> 0.91239 0.912300 -> 0.9123   What is the best way to achieve this in Java?


There is a type of questions like  where the structure is simple enough that a question title surely covers the entire description without further explanation.  Requiring question body for those questions would be redundant and would impose an unnecessary burden on users.  So what I think would be nicer is to have a checkbox, saying "Empty body" to omit the body input.

Let's say that I want to ask a simple question like "How are planes able to fly?" or "Where on the internet can I find the list of all presidents of USA?". Asking these questions I'd have to add a description because otherwise I get the error:     Body is missing.   What if I have nothing to add? Should I repeat the question? In my opinion adding why I need the answer to these questions is useless and clutters the thread.  Edit: This is not the same question as mentioned "How to leave body of question empty?". I'm asking why can't it be empty. Ramhound's comment on that question does not satisfy me at all. Not exery question needs more details. Examples what I should add as a description to mentioned above questions are welcome so I can feel what to add to my future simple questions.  The Tin Man's comment also doesn't satisfy me. In my opinion, SE is also for simple questions and they are not always simple.


The "Top Network Askers" sidebar shows a bunch of similar gravatars for users, where their gravatars are actually something different. In this case they all seem to link to  <img src="https://www.gravatar.com/avatar/?s=18&amp;d=identicon&amp;r=PG&amp;s=30"/>   Clicking through to the users shows different gravatars (since you can't click on the image, here are a few):

Same gravatar is displayed for different users in the stackexchange.com , under the Top Network Askers in the right side bar.   The red circled image's source (<img src=) are from   https://www.gravatar.com/avatar/?s=18&d=identicon&r=PG&s=30                                ^   Seems the gravatar id is missing here in the image source.  For an example from the list, the user  gravatar id should be    https://www.gravatar.com/avatar/66c66c4d97a7bc3859a85253f003e1fb?s=18&d=identicon&r=PG&s=30   but it is mapped with   https://www.gravatar.com/avatar/?s=18&d=identicon&r=PG&s=30   which caused the display issue.


I came across a question today which was older than 30 days, had just 30 views, and gotten a bounty (from a third person) today. It adheres to all of the criteria for the , therefore my question: can questions with an active bounty be automatically deleted by the roomba?  The dupe target does answer the issue: questions with an active bounty will not be automatically deleted. Can we fix the roomba help-page to reflect that? (If you're fixing it anyway, please also in-line the link to  at the end.)

Originating from this question on Meta Stack Overflow (), we wondered why a specific question was deleted, which met all requirements for deletion, but had a bounty on it.  As Mad Scientist sums up in that post, a question does quality for deletion, even if it has a bounty on it.  Currently, the requirements for deletion are:     If the question is more than 30 days old, and ...      has −1 or lower score has no answers is not locked ...or...      it was closed and migrated to a different site ... it will be   automatically deleted.   This seems undesired, even a bug to me.  Therefore, I suggest to add:     Doesn't have an active bounty on it.   This prevents questions with bounties on it from being auto-deleted.  (As a side note: Questions that have a bounty can't be closed without intervention of a moderator, so why would the Community user delete an open question in this period?)