I've built a custom linux system using Yocto.  It uses busybox.  I have most everything working, except I can't have a static dns resolver address because /etc/resolv.conf is being deleted on every boot, and replaced with a link to /var/run/resolv.conf.  I think this is being caused by a script called /etc/volatile.cache.  I've deleted this script, but I think another script /etc/init.d/populate-volatile.sh recreates it every time.  Certainly I could add my own script, something like /etc/rc5.d/S90set-resolv that writes a value to resolv.conf, but that seems like an extremely strange way to do it.  Does anybody know what is going on here?  What is the correct way to set a nameserver address in this situation?

I am having an issue where DHCP (I though as I read in other similar topics) is clearing the /etc/resolv.conf file on each boot. I am not sure about how to deal with this since the post I have found (,  and some others) are for Debian based distros or other but not Fedora.  This is the output of ifcfg-enp0s31f6 so for sure is DHCP:  cat /etc/sysconfig/network-scripts/ifcfg-enp0s31f6  HWADDR=C8:5B:76:1A:8E:55 TYPE=Ethernet DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=no IPV6_AUTOCONF=no IPV6_DEFROUTE=no IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=enp0s31f6 UUID=0af812a3-ac8e-32a0-887d-10884872d6c7 ONBOOT=yes IPV6_PEERDNS=no IPV6_PEERROUTES=no BOOTPROTO=dhcp PEERDNS=yes PEERROUTES=yes   In the other side I don't know if Network Manager is doing something else around this.  Update: Content of NetworkManager.conf (I have removed the comments since are useless)  $ cat /etc/NetworkManager/NetworkManager.conf  [main] #plugins=ifcfg-rh,ibft dns=none  [logging] #domains=ALL   Can I get some help with this? It's annonying be setting up the file once and once on every reboot.  UPDATE 2  After a month I'm still having the same issue where file gets deleted by "something".   Here is the steps I did follow in order to make a fresh test:   Reboot the PC After PC gets restarted open a terminal and try to ping Google servers of course without success:  $ ping google.com ping: google.com: Name or service not known  Check the network configuration were all seems to be fine:  $ cat /etc/sysconfig/network-scripts/ifcfg-enp0s31f6  NAME=enp0s31f6 ONBOOT=yes HWADDR=C8:5B:76:1A:8E:55 MACADDR=C8:5B:76:1A:8E:55 UUID=0af812a3-ac8e-32a0-887d-10884872d6c7 BOOTPROTO=static PEERDNS=no DNS1=8.8.8.8 DNS2=8.8.4.4 DNS3=192.168.1.10 NM_CONTROLLED=yes IPADDR=192.168.1.66 NETMASK=255.255.255.0 BROADCAST=192.168.1.255 GATEWAY=192.168.1.1 TYPE=Ethernet DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=no  Restart the network service:  $ sudo service network restart [sudo] password for <current_user>:  Restarting network (via systemctl):                        [  OK  ]  Try to ping Google servers again, with no success:  $ ping google.com ping: google.com: Name or service not known  Check for file /etc/resolv.conf:  $ cat /etc/resolv.conf  cat: /etc/resolv.conf: No such file or directory  File doesn't exists anymore - and this is the problem something is deleting it on every reboot Create the file and add the content of DNS:  $ sudo nano /etc/resolv.conf   Ping Google servers this time with success:  $ ping google.com PING google.com (216.58.192.110) 56(84) bytes of data. 64 bytes from mia07s35-in-f110.1e100.net (216.58.192.110): icmp_seq=1 ttl=57 time=3.87 ms    Any ideas in what could be happening here?


how to get user location based on IP address using javascript ? how to display checkbox if user is coming from other country and hide the checkbox if the user is not coming from other country ?

I need to somehow retrieve the client's IP address using JavaScript; no server side code, not even SSI.  However, I'm not against using a free 3rd party script/service.


I have a document like this  1 0.2 1 0.3 1 0.1 2 0.8 2 0.5 2 0.3   I want to add the lines if the first column are the same and output something like this  1 0.6 2 1.6   How can I do this with awk? Or maybe it is easier with other tools?  PD: the first column are the same for each 3 lines always, so maybe make an array that adds $2 until line count goes to 3 and print? something like this awk 'BEGIN {x=0,n=1} {n++,x=x+$3}'but with some condition?

Considering below file:   0,2,,,10 0,2,,,15 0,1,,,984 0,2,,,9 1,14,,,5   Using awk, I need to calculate the total value in $5 per each $2.  The desired output would look like below:   2,34 1,984 14,5


Please tell me how to summon him. Does it have be hard-mode?

I am wondering how to summon the Golem boss in Terraria on PC. I have defeated Plantera.  How do I summon the Golem boss?


i found a equation that holds for any natural number of n and any $x_i \ne x_j$ as follows:   $$\sum\limits_{i = 1}^{n } {\prod\limits_{\substack{j = 1\\j \ne i}}^{n } {\frac{{x_i }}{{x_i  - x_j }}} } = 1$$  when n=2, it is given by  $$\frac{x_1}{x_1-x_2}+\frac{x_2}{x_2-x_1}=\frac{x_1 - x_2}{x_1 - x_2} = 1$$  when n=3, it is given by  $$\frac{x_1^2}{(x_1-x_2)(x_1-x_3)}+\frac{x_2^2}{(x_2-x_1)(x_2-x_3)}+\frac{x_3^2}{(x_3-x_1)(x_3-x_2)}=1$$  But, how can I prove for general $n$?

If $\lambda_1,\dots,\lambda_n$ are distinct positive real numbers, then  $$\sum_{i=1}^n \prod_{j\neq i} {\lambda_j\over \lambda_j-\lambda_i}=1.$$ This identity follows from a probability calculation that you can find at the  top of page 311 in the 10th edition of Introduction to Probability Models by Sheldon Ross.   Is there a slick or obvious explanation for this identity?   This  question is sort of similar to ; clearly algebra is not my strong suit!


Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.NoClassDefFoundError: org/jxmpp/jid/Jid         at java.lang.Class.getDeclaredMethods0(Native Method)         at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)         at java.lang.Class.privateGetMethodRecursive(Class.java:3048)         at java.lang.Class.getMethod0(Class.java:3018)         at java.lang.Class.getMethod(Class.java:1784)         at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544)         at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526) Caused by: java.lang.ClassNotFoundException: org.jxmpp.jid.Jid         at java.net.URLClassLoader.findClass(URLClassLoader.java:381)         at java.lang.ClassLoader.loadClass(ClassLoader.java:424)         at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)         ... 7 more   when i execute my code from intellij it is working fine but while executing jar like java -jar test.jar it giving above error

I am getting a NoClassDefFoundError when I run my Java application.  What is typically the cause of this?


$G$ is a non trivial group. There exists a non trivial homomorphism $h:\mathbb Z\to G$. Prove or disprove! When $G$ is finite and cyclic I get the non trivial homomorphism easily. When $G$ is the non abelian group of symmetries on three symbols, I can't get the homomorphism. Similarly I have to tackle the cases of infinite and also uncountable groups. What is the best way to answer this question involving all cases? Help please.

Let $G$ be a group.  If $G$ is non-trivial, then there exists a non-trivial homomorphism from $\mathbb{Z}\to G$.  How would one prove the above statement?


My favorite animal are dogs.  Is this acceptable?  I believe this is ok because I see "animal" as one species and "dogs" as the variety of breeds.  Of course, the best answer would be "my favorite animal is the dog" but that's not the point.   Could someone give me a clear, technical answer as to whether or not this is acceptable (grammar)?  Thanks

My fish's native habitat is rice fields. My fish's native habitat are rice fields.   Which one is correct? I'm pretty sure it's the first, since 'is' modifies 'habitat,' but it still sounds weird...


How can I enforce that a base class method is not being overridden by a derived class?

Is anyone aware of a language feature or technique in C++ to prevent a child class from over riding a particular method in the parent class?  class Base { public:     bool someGuaranteedResult() { return true; } };  class Child : public Base { public:     bool someGuaranteedResult() { return false; /* Haha I broke things! */ } };   Even though it's not virtual, this is still allowed (at least in the Metrowerks compiler I'm using), all you get is a compile time warning about hiding non-virtual inherited function X.


What is a  and when do I use it?  What I tried :        <title>example</title>
This is my first site
     hello, nice to meet you!I really need help!
I am new to web development and I am excited to start this journey. I hope that I make some friends during this experience.

I would like to ask for some simple examples showing the uses of <div> and <span>.   I've seen them both used to mark a section of a page with an id or class, but I'm interested in knowing if there are times when one is preferred over the other.


I'm allowing users to upload a file, however I need to check if the file has a proper name (since using multiple '.' characters throws off the .split() method). Here's what I have so far:  //Check if filename has more than 1 period character in the whole thing.  if(this.file.name.???){   this.fileNameAccepted = true; } else {   this.fileNameAccepted = false; }

See code:   var file1 = "50.xsl"; var file2 = "30.doc"; getFileExtension(file1); //returns xsl getFileExtension(file2); //returns doc  function getFileExtension(filename) {     /*TODO*/ }


I am looking to see how I would set up my :notice to incorporate a helper method, at the moment I have this and get 'undefined method to_dollars':  notice: "Thank you for your payment of #{to_dollars(amount)}"   Controller  def create   @donation = @campaign.donations.create(donation_params)     if @donation.save_with_payment       amount = @donation.donation_amount       redirect_to @campaign, notice: "Thank you for your payment of #{to_dollars(amount)}"     else      flash[:notice] = @donation.errors      render :new   end end   My helper method is simply (unless anyone has a better way of doing it)  def to_dollars(amount)   convert = amount / 100   number_to_currency(convert, unit: "&#36;", separator: ".", delimiter: "") end   All donation_amounts are saved in cents so just want to convert them to dollars.

I'm getting a NoMethodError when trying to access a method defined in one of my helper modules from one of my controller classes. My Rails application uses the helper class method with the :all symbol as shown below:  class ApplicationController < ActionController::Base   helper :all   .   . end   My understanding is that this should make all of my controller classes automatically include all of the helper modules within the app/helpers directory, therefore mixing in all of the methods into the controllers. Is this correct?  If I explicitly include the helper module within the controller then everything works correctly.


I have a red bmx bike with flat plates on both sides in the front it has circles through them I don't know what kind of bike it is it's just the frame I bought from a friend he said he thought it was a diamond back but I never seen one of them made like this one can anyone help me out. Thanks

We often get questions on bicycles.stackexchange about identifying a bicycles manufacturer, model, make, and year.  Often these questions are downvoted or closed -- usually with a comment attached to them that it's not necessary to know the exact model/make/year of a bicycle if you want to fix, repair, or ride your bike. Why should owners not care about the model/make/year of their bicycle? Especially when it comes to less expensive bikes (aka BSOs) and BMX bicycles? This is intended as a canonical question that we can point closed questions to. Also see      (generally not helpful for identifying a brand/model)


A simple question: Can someone help me declare a long long array in Java? I've tried to cast it, but no luck:  (long long)[] sum = new (long long)[10];   Also, I searched across the internet and didn't really find anyone who uses long long to define an array Any help please?

In C++, I enjoyed having access to a 64 bit unsigned integer, via unsigned long long int, or via uint64_t. Now, in Java longs are 64 bits, I know. However, they are signed.  Is there an unsigned long (long) available as a Java primitive? How do I use it?


The mass of a Lithium $\rm ^6_3Li$ nucleus is $9.998×10^{−27}\ \rm kg$. It consists of $3$ neutrons and $3$ protons. The Lithium nucleus is traveling in the north direction at speed of $3.67\ \rm km/s$.   If the nucleus suddenly enters a $2.0\ \rm T$ magnetic field directed from east to west, in what direction will the Lithium nucleus be accelerating at the instant it enters the magnetic field.  I want to know the name of the used rule and if anyone can suggest a site or video to learn more about this concept.

Need help in understanding the direction of magnetic force in the magnetic field!Totally confused by directions.  Why is it that magnetic force is perpendicular to the direction of magnetic field and velocity of charged particle. Why is it(force) not in the same direction as the magnetuc field


What is the word for a person who acts super nice to you to impress others and build his image, but in real life, he doesn't actually mean it? For example, what would you call Cindrella's stepmom who treats her well in front of her dad, however, when he dies she makes Cindrella do chores? I need this word to describe a ruler who is just pretending to protect his people for the sake of his image and doesn't really care about whatever happens to them.

I'm looking for a word that can describe a person who does nice things for other people (e.g holding the door open, carrying someone's things) but only for self gain; this person only does nice things to make themselves look good in the eyes of others, but doesn't actually care about the well-being of the people they're helping.


There are $N$ balls of $M$ different colors in a box i.e $c_1$ balls of color $1$ and so on. $c_1 + c_2 + \dots + c_M=N$, $c_1, c_2, \dots, c_M$ are known. We are looking for a ball of a particular color, say, $j$.The balls are picked from the box randomly, and if the color of the ball picked up say $i$ is such that, $i \ne j$, all the balls of color $i$ disappear. How many times do I need to pick to get a ball of color $j$ on average?

There are $n$ types of balls in an urn; $a$ balls of type $1$ , $b$ balls of type $2$ , $c$ balls of type $3$ and so on. Now balls are drawn until a ball of type $1$ is obtained with condition that if a ball of type $i$ is drawn at any moment ( $i \neq 1$ ) then all balls of type $i$ will be removed from the urn. What is the expected number of draws done? (In one draw, all balls of that particular type are removed)  My approach for $n = 3$ is like:  expectation value = $a/(a+b+c)+2(ba/(a+b+c)(a+c)+ca/(a+b+c)(a+b))+3(bca/(a+b+c)(a+c)a+cba/(a+b+c)(a+b)a)$  But it's messy , is there any general form for n type of balls ?


I've got two noetherian rings $A\subset B$ such that $B$ is a finite $A$-module. Now, if I consider the associated map between spectra that given $q \in \operatorname{Spec} B$ consider $q \cap A \in \operatorname{Spec}  A$ and I should demonstrate it has finite fibers.  I really don't know how to even start. I tried to use the fact that the extension is integral etc but i didn't manage to do anything. Ty for the help

Let $A$ be a commutative ring with identity and $B$ a finitely generated $A$-algebra that is integral over $A$.  If $\mathfrak{p}$ is a prime ideal of $A$, there are only finitely many prime ideals $P$ of $B$ such that $P\cap A=\mathfrak{p}$.   Let me say that I am aware of  answer, but I can't follow through the hint.  Also, I don't know how to extend to work for algebras rather than extension rings.


I am trying to install Java on Ubuntu 18.04. by running:  sudo apt install oracle-java14-installer   But when I reach the part where I have to accept the license agreement there is link leading to the Oracle page, but when I click on that link it's "Page not found". I'm stuck on this page?    How do I accept the license agreement? I'm using .

After a recent update, ttf-mscorefonts-installer prompted me to accept its license agreement.     ┌─────────────────┤ Configuring ttf-mscorefonts-installer ├─────────────────┐  │                                                                           │   │ TrueType core fonts for the Web EULA                                          │                                                                               │ END-USER LICENSE AGREEMENT FOR MICROSOFT SOFTWARE                             │                                                                               │ IMPORTANT-READ CAREFULLY: This Microsoft End-User License Agreement           │ ("EULA") is a legal agreement between you (either an individual or a          │ single entity) and Microsoft Corporation for the Microsoft software           │ accompanying this EULA, which includes computer software and may include      │ associated media, printed materials, and "on-line" or electronic              │ documentation ("SOFTWARE PRODUCT" or "SOFTWARE"). By exercising your          │ rights to make and use copies of the SOFTWARE PRODUCT, you agree to be        │ bound by the terms of this EULA. If you do not agree to the terms of          │ this EULA, you may not use the SOFTWARE PRODUCT.                              │                                                                               │                                  <Ok>                                         │                                                                           │   └───────────────────────────────────────────────────────────────────────────┘    Screenshot:   For some reason my terminal will not allow me to accept, or for some reason I am pressing the wrong hotkey...  I've tried every letter on the keyboard and Enter among others...  I'm sure there is a very simple and obvious solution to this.  I've also just tried to remove the package completely however the terminal states that due to the package not being correctly installed, I should reinstall the package before removing it.  Very frustrating!  Essentially, because I cannot successfully install this package, I can't really ever upgrade my system because I always have to end up terminating the terminal with the license agreement (thus the upgrade fails).


I know there are a gazillion mixes possible in iTunes and that the size and genre of such mixes are determined by some top-secret algorithm running behind the scene. However, I am really curious to know how many one can possibly have at a time on a MacBook. I have read some users claiming to have up to 12 mixes on their 27" Macs but I am using a 13" MacBook so guess 12 isn't possible for me. Currently I have 6; is that the limit? Has anyone witnessed more than 6 on this screen size (13")?  P.S. I am NOT referring to genius playlists which anyone can build with a song. I am specifically talking about Genius Mixes that iTunes creates automatically (if Genius is activated on the account).

Every so often I'll add a couple hundred new songs to my iTunes and discover a new mix has been created. It makes me wonder then, exactly how many mixes are there, what genres are they, etc.  Here's a photo, in case you're unsure what I'm talking about.


So if  is your commander and has yet to be played, does his ability still exile creatures that would normally be destroyed, or does he have to be on the battlefield for that to happen?

has an ability that functions whilst in the command zone. As a newbie to the Commander format, that leaves me unclear about something:  Whilst a Commander is in their Command zone and remains there, what effect do they have on the game?   Are all of a Commander's abilities active? (e.g. ) Can they use their activated or mana abilities? (e.g. ) Can they do anything else (apart from being able to be cast)?   I suspect all their abilities are active and can be used, but I've been told only the ones that specifically mention being in the command zone (e.g. Oloro's ability) are active.


What kind of SQL is needed to group by GroupID and then concatonate all of the Name values into 1 row with comma's separating the values?  So this:  GroupName   GroupID Name All screens 139091  Business All screens 139091  Business  All screens 139091  Cafeteria/Bathrooms All screens 139091  Lobby   Would become this:  GroupName   GroupID Name All screens 139091  Business, Cafeteria/Bathrooms, Lobby   This would need to be done on as many GroupID's as there are in the table and I am guessing skip duplicates. Is this better done on the C# side? The SQL version is 2008 R2  Group_Concat does not exist for use in SQL Server

I'm trying to migrate a MySQL-based app over to Microsoft SQL Server 2005 (not by choice, but that's life).  In the original app, we used almost entirely ANSI-SQL compliant statements, with one significant exception -- we used MySQL's group_concat function fairly frequently.  group_concat, by the way, does this: given a table of, say, employee names and projects...  SELECT empName, projID FROM project_members;   returns:  ANDY   |  A100 ANDY   |  B391 ANDY   |  X010 TOM    |  A100 TOM    |  A510   ... and here's what you get with group_concat:  SELECT      empName, group_concat(projID SEPARATOR ' / ')  FROM      project_members  GROUP BY      empName;   returns:  ANDY   |  A100 / B391 / X010 TOM    |  A100 / A510   So what I'd like to know is: Is it possible to write, say, a user-defined function in SQL Server which emulates the functionality of group_concat?   I have almost no experience using UDFs, stored procedures, or anything like that, just straight-up SQL, so please err on the side of too much explanation :)


Why does coke fizz more when you add ice to it?

I read that the soda's temperature allows it to contain its $\text{CO}_2$: colder means it can retain its bubbles better.  So, why does soda fizz when it meets ice?  If anything, because the soda is made colder, it should retain its gas better, as per above. The ice is taking away energy from the soda, thus freezing. Won't heating, not freezing, encourage the gas to escape, or is it not an energy matter?


I have a Dell Insiron laptop, which currently runs windows. There is a a logo of Ubuntu on my computer, I dont know why. Can anyone tell me why that is?   And I have downloaded the latest version of Ubuntu from your website.  Now I want to delete Windows and install Ubuntu as the permanent operating system, without other Grub loader type of things, just like windows - which loads like normal. Please give me guidance about that, and I don't want to delete any personal data.

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


I am about to purchase the Alienware m15 r3, and I usually dual boot all my computers, but I have seen some people experience some difficulties while trying to install ubuntu on an Alienware, and I haven't seen any posts about the new Alienware, has anyone install ubuntu on the Alienware m15 r3? If so, can you share what resources, problems you had, and the steps you followed? Thanks!!

I have a device on which I would like to install Ubuntu. How do I find out if Ubuntu will work on it?


(Sorry about poor english) It looks normal in solid view, but only mesh silhouette is visible in material preview or rendered view. I think it's a optional driver(20.12.1) problem, and I downgrade to the recommended version(20.11.2), but it's showing the same thing. The previous driver was 20.4.2, it works fine.

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?


I'm trying to install the latest Python version on my workstation at work. Unfortunately I don't have root access, and they won't do it for me, so I have to compile from source and put it in ~/local/bin.  I've downloaded the source, and run ./configure --prefix=~/local && make && make install. However, I get an error that says ModuleNotFoundError: No module named '_ctypes' when it tries to install pip.  According to here:    I need to install libffi-dev. So I downloaded the source and ran ./configure --prefix=~/local && make && make install there.  Now my problem is that it installed the .so files in ~/local/lib64, and the installer tells me I need to link against the library by using libtool or the LD_LIBRARY_PATH env var or some linker flags.  I need to run the python make but it needs to point to both that library directory and the default one. I can't seem to figure out how to do it because none of the options suggested are working.  Thanks!

I'm trying to install python3 for one of remote hosting over ssh. I don't have root access. Installation was done with:  wget https://www.python.org/ftp/python/3.7.0/Python-3.7.0.tgz tar xvzf Python-3.4.3.tgz ./configure --prefix=$HOME/.local make make install   This installs Python 3, however in the end of installation this error occurs:  File "/home/someusername/Python-3.7.0/Lib/ctypes/__init__.py", line 7, in <module>     from _ctypes import Union, Structure, Array ModuleNotFoundError: No module named '_ctypes'   python3 is installed, but pip install failed. After some research it seems that libffi is missing. After using wget to obtain libffi-3.2.1, it is installed with:  ./configure --prefix=$HOME/.local make make install   This shows it is installed:  someusername@a2plcpnl079 [~/.local/lib]$ ls ./  ../  libffi-3.2.1/  libpython3.7m.a*  pkgconfig/  python3.7/ someusername@a2plcpnl079 [~/.local/lib]$ cd libffi-3.2.1/ someusername@a2plcpnl079 [~/.local/lib/libffi-3.2.1]$ ls ./  ../  include/ someusername@a2plcpnl079 [~/.local/lib/libffi-3.2.1]$ cd include someusername@a2plcpnl079 [~/.local/lib/libffi-3.2.1/include]$ ls ./  ../  ffi.h  ffitarget.h someusername@a2plcpnl079 [~/.local]$ cd lib64 someusername@a2plcpnl079 [~/.local/lib64]$ ls ./  ../  libffi.a  libffi.la*  libffi.so@  libffi.so.6@  libffi.so.6.0.4*   Now it is necessary to reconfigure the build of python-3.7.0 so it uses the local libffi. I tried a number of variations but still can't install pip.  # .bash_profile  # Get the aliases and functions if [ -f ~/.bashrc ]; then         . ~/.bashrc fi  # User specific environment and startup programs  PATH=$PATH:$HOME/.local/bin:$HOME/bin  export PATH export HISTTIMEFORMAT="%d/%m/%y %T " export PATH="$HOME/.local/bin:$PATH" export LD_LIBRARY_PATH=$HOME/.local/lib64   Something like this was attempted:  $ ./configure --with-system-ffi --prefix=$HOME/.local LDFLAGS="-L/home/someusername/.local/lib64" LIBS="-L/home/someusername/.local/lib"   The same error occurred, so the question is how to correctly invoke Python-3.7.0 configure to use the local libffi library in order to fully install python?


Prove $\vec{\nabla} \cdot\left ( \vec{A}\times\vec{B} \right )=\vec{B}\cdot\left ( \nabla \times\vec{A} \right )-\vec{A}\cdot\left ( \nabla \times\vec{B} \right )$  I have expanded the LHS for this and obtain a horrible expression that would be even tedious to put them into latex form without a headache.  I attempted to rearrange the LHS so as to obtain the RHS but to no avail.  any help is appreciated.

Verify the vector identity:  $\nabla \cdot (a  \times b) = b \cdot \nabla \times a - a \cdot \nabla \times b $  Given that:  $a = (R_a, S_a, T_a)$, $b = (R_b, S_b, T_b)$ and $\nabla = (\frac{\partial} {\partial x},\frac{\partial} {\partial y},\frac{\partial} {\partial z} )$.  Where $R_i, S_i, T_i$ have continuous partial derivatives.   I attempted it on paper but cannot get it to work. Can anyone show me how this is done?  My working:  LHS:  $\nabla \cdot (a  \times b) = \frac{\partial}{\partial x}(S_a T_b - S_b T_a) + \frac{\partial}{\partial y}(T_a R_b - R_a T_b) + \frac{\partial}{\partial z}(R_a S_b - R_b S_a)  $  RHS:  $\nabla \times a = (\frac{\partial}{\partial y} T_a - \frac{\partial}{\partial z} S_a)\hat i - (\frac{\partial}{\partial x} T_a - \frac{\partial}{\partial z} R_a)\hat j + (\frac{\partial}{\partial x} S_a - \frac{\partial}{\partial y} R_a)\hat k$  $b \cdot (\nabla \times a) = R_b(\frac{\partial}{\partial y} T_a - \frac{\partial}{\partial z} S_a) - S_b(\frac{\partial}{\partial x} T_a - \frac{\partial}{\partial z} R_a) + T_b(\frac{\partial}{\partial x} S_a - \frac{\partial}{\partial y} R_a)$  Now I computed the other part of the RHS as well however I can't see how I would be able to maninipulate it into the LHS.  Anyone have any idea?


I'm looking for a story I read in the 90s (probably written much earlier) about a man who is part of some sort of scientific group that discovers a way to build a doomsday weapon capable of cutting the planet in half. All it requires is a coil of wire and some commonly available chemicals.  The man discusses the matter with his wife, and they decide that      no one can be trusted with such dangerous information, so at their next meeting he murders everyone in the group by leaving a drop of acid to slowly burn into a cylinder full of nerve gas.   In the end,      his wife poisons him because she believes that not even her husband can be trusted not to someday use his knowledge to destroy the Earth.

I read a short story in the early 1980s, probably from the 1960s or 1970s, that began with a scientist telling his wife that he and several colleagues had figured out how a combination of simple household chemicals and loop of hot wire could destroy the whole Earth (or maybe kill everyone on Earth).  The scientists take this discovery to somebody in the government, but the governmental response to the danger is inconclusive.  Eventually, in order to protect the people of Earth, the protagonist and his wife decide to murder everyone else who might know the secret.  They kill them all without a hitch, and the scientist, tired out, heads to bed.  His wife looks once more at their sleeping infant, then kills her husband as well.  Does anybody know the title and author of this story?


I currently have the Canon EOS 550D with the 18-55mm IS kit lens. I am primarily looking for greater telephoto reach, as I have found the 55mm length to be quite limiting at times. So, I was considering the  which would be a good general purpose replacement for the kit lens, versus the  that would give slightly greater telephoto reach while complementing the kit lens.  What are the pros & cons of each like optical quality, effort in changing lenses etc, considering the fact that the 18-200mm lens is almost 3x as expensive as the 55-250mm one?  Note that it's highly unlikely that I'll be printing photographs larger than A4 size.

There seems to be a preference for to have the    18 mm - 55 mm 55 mm - 250 mm   lenses, but no mention of why they're better than a single 18-200mm. Could someone please explain why the two separate are better than the one combined, and if anyone has quantified this difference?  (I'm curious about Canon in particular.)


The following MWE  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage[many]{tcolorbox}  \newtcbtheorem{defbox}{Definition}% {   enhanced,     arc=0mm,     interior style={white},     attach boxed title to top center= {yshift=-\tcboxedtitleheight/2},     fonttitle=\bfseries,     fontupper=\itshape,     colbacktitle=white,coltitle=black,     boxed title style={size=normal,colframe=white,boxrule=0pt} }  \begin{document}  \begin{defbox}{Theorem Name} Description \end{defbox}  \end{document}   Produces the following (cropped) output   But my editor also says that there is a runaway argument. Likely for the same reason, there is an out of place D before the tcbtheorem.  My error log (I think?) says   main.tex, line 19 Runaway argument?  { ! Paragraph ended before \tcb@theo@label was complete. <to be read again>                     \par  l.19 D       escription I suspect you've forgotten a `}', causing me to apply this control sequence to too much text. How can we recover? My plan is to forget the whole thing and hope for the best.  ! Extra }, or forgotten \endgroup. <argument> \tcb@theo@label {\par }                                   {D} l.19 D       escription I've deleted a group-closing symbol because it seems to be spurious, as in `$x}$'. But perhaps the } is legitimate and you forgot something else, as in `\hbox{$x}'. In such cases the way to recover is to insert both the forgotten and the deleted material, e.g., by typing `I$}'.   While I partially understand what a runaway argument is, I haven't found it here, and I don't know what to do next.  Any help would be appreciated.

I'm using the package tcolorboxwith the theorems library and it's giving me the following problem:  \documentclass[12pt,letterpaper]{article} \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{graphicx} \usepackage{fourier}  \usepackage{tcolorbox} \tcbuselibrary{theorems} \newtcbtheorem[number within=section]{teorema}{Teorema}% {colback=black!5,colframe=black!35!black,fonttitle=\bfseries}{th}  \begin{document} \section{MyTheorem} \begin{teorema}{MyTheorem} This text loses one characther. \end{teorema} \end{document}   And when I type between the \begin{teorema} and \end{teorema}, it loses the first character. And if try to use the \input command in that environment I get a error related to:     missing \endcsname inserted.   One solution is typing two times the first letter of my text... but I don't like that.


The reason I stopped smoking was that all my friends had already stopped smoking.   The reason I stopped smoking is that all my friends had already stopped smoking.   -  I wonder if the verb "was" is replaced for "is", which reflects the present time. I think it's not possible because the time I stopped smoking was the past, and the cause inspiring the determination to stop smoking was also the past thing.  Is it right?

For example:  "Last week, I found out that NASA stands for 'National Aeronautics and Space Administration.'"  or  "Last week, I found out that NASA stood for 'National Aeronautics and Space Administration.'"


Question : Prove that $$ \sum_{k=1}^n\frac{1}{\sqrt{k}}\le 2\sqrt{n}-1 $$ for all positive integers $n$.  I've been thinking a solution for this question for hours but still can't solve it.

I'm trying to solve  proposed by the department of mathematics of Oxford University. I don't know how to give a valid proof for the third one which says the following:     Prove that for $n \in \mathbb{N}^{\ge 1}$: $$ \sqrt{n} \le  \sum_{k=1}^n \frac{1}{\sqrt{k}} \le 2 \sqrt{n} - 1 $$   My first approach has been to convert the summation into a function in terms of $n$ so that I could find the maximum and minimum values in the interval. However, there doesn't seem to be an easy way to express the summation as a function. Thanks in advance!


I have type the following code.  \begin{align*} \RR = \left\{ a_1 = \begin{pmatrix}                      0 & 0 \\                      0 & 0                     \end{pmatrix},               a_2 = \begin{pmatrix}                      1 & 0 \\                      0 & 0                     \end{pmatrix},               a_3 = \begin{pmatrix}                      0 & 1 \\                      0 & 0                     \end{pmatrix},               a_4 = \begin{pmatrix}                      0 & 0 \\                      0 & 1                     \end{pmatrix}  \\               a_5 = \begin{pmatrix}                      1 & 1 \\                      0 & 0                     \end{pmatrix},               a_6 = \begin{pmatrix}                      0 & 1 \\                      0 & 1                     \end{pmatrix},               a_7 = \begin{pmatrix}                      1 & 1 \\                      0 & 1                     \end{pmatrix},               a_8 = \begin{pmatrix}                      1 & 0 \\                      0 & 1                     \end{pmatrix}          \right\} \end{align*}

I have a multi-line equation that I want to have matching sized parentheses. The advice I read online was to use \left( equation \right. \\ left. rest-of-equation \right) . However, this syntax leaves first half of the equation unaware of what is in the second half. For example, if you include a square root term after the break, the second parenthesis will be larger than the opening parenthesis. When you are using the aligned environment to split a long equation this can look somewhat offputting.    Compare the top equation to the bottom one. The parentheses match in size for the bottom equation, but the left hand parentheses for the top one is  noticeably smaller.  Top Code:   \begin{aligned}[t]   \gamma_{\text{u}} + \frac{1}{108}   \left(57\gamma_{\text{er}} \right. &+  38\gamma_{\text{se}}\\ & {}\pm  \left.\sqrt{2601 \gamma_{\text{er}}^2 + 3648  \gamma_{\text{er}}\gamma_{\text{se}} + 1444 \gamma_{\text{se}}^2}  \right)   \end{aligned}   Bottom Code:  \begin{aligned}[t] \gamma_{\text{u}} + \frac{1}{16} \left(9\gamma_{\text{er}}  +  6\gamma_{\text{se}} \pm  \sqrt{49 \gamma_{\text{er}}^2 + 76 \gamma_{\text{er}}\gamma_{\text{se}} + 36 \gamma_{\text{se}}^2} \right) \end{aligned}


Here's a corollary of AC stating that: if there exists an onto mapping $f:A\to B$, then there exists a 1-1 mapping $g:B\to A$. What I'm confused about is that whether or not  AC can be derived from this proposition, in return? I have tried but haven't found a proof. Any help would be appreciated.

Theorem. Let $X$ and $Y$ be sets with $X$ nonempty. Then (P) there exists an injection $f:X\rightarrow Y$ if and only if (Q) there exists a surjection $g:Y\rightarrow X$.  For the P $\implies$ Q part, I know you can get a surjection $Y\to X$ by mapping $y$ to $x$ if $y=f(x)$ for some $x\in X$ and mapping $y$ to some arbitrary $\alpha\in X$ if $y\in Y\setminus f(X)$. But I don't know about the Q $\implies$ P part.  Could someone give an elementary proof of the theorem?


What happens when FILE parameter is not given in grep ls folder1 folder2 new.txt new.cpp folder3 # -> folder 3 has all .cpp files with main grep -rl -e "int main" new.cpp folder3/one.cpp folder3/two.cpp  From   If no FILE is given, recursive searches examine the working directory  But if i removed -r it doesn't give any output and still running like infinite loop grep -l -e "int main"   From man pages it;s already recursive if there's no FILE parameter but if -r is removed nothing's happening. I'm a beginner what am i missing?

Grep works when I use is with ls | but when I try the command by itself, it just gives me a blinking cursor that never goes away on the next line (as if it's running a command).  For example, I tried:  ls | grep zip   while in the bin directory and got a list of files, but plain grep zip in the same directory gives me the problem stated above.


We loosely remember some things about the movie. But it's based on memories so we may be wrong. It was about some scientists that were sent on a distant planet to kind of rescue some other scientists that already have been there some time. Their job was to find a spot to colonize the planet. We think that each of the scientists sleep in some kind of cryostasis, and they are scattered over the planet. Maybe they search for water or some other habitable parameters.  Different things went wrong and they find some scientists. Then they somehow have a decision to make between two scientists, one of them reports about very habitable conditions. So they decide to rescue this one and as it turns out, the scientist lied to them: He just wanted to be rescued. So in the end there are some fights on icy or rocky terrains. Maybe the movie also involves a robot type that is kind of rectangular with a black display on it - but we are not sure about it.  Furthermore there may be some kind of relationships between the scientists, the rescued scientist and a woman of the rescue team were a couple. In the end they quickly have to leave the planet - we don't know why.  Can anyone point us into the right direction ? :-(

It's a (relatively) recent movie about a kid whose scientist father is missing or presumed dead.  The kid experiences strange situations (e.g., books from a case fall off).  In the end, it was the father the one that was throwing those books to draw the attention of the kid.  Does anyone know the name of this film?


I need help solving this problem.   I don't really know how to solve it.  Here:   Suppose A is a closed subset of a complete metric space M. Show that A is complete in the induced metric.

Let $(X, d(x,y))$ be a complete metric space. Prove that if $A\subseteq X$ is a closed set, then $A$ is also complete.  My attempt: I tried to prove that every Cauchy sequence $(b_n)$ of points of $A$ converges to a point $b\in A$. However could not figure out the exit way. Maybe I am on the wrong track. Could you please help me?  edit: More from my attempt:  Suppose $A$ is a closed set and let $(x_n)$ be a sequence of points $A$ such that $\lim_n x_n\to b$.  Suppose now that $A$ has the property that $b\in A$, whenever $x_n$ converges to $b$. We know that every element of $x_n$ which is convergent in $X$ also converges to a point in $A$. Since $x_n$ is a Cauchy sequence in $A$, it must converge to a point $y\in A$. But the limit of a convergent sequence is unique.   Take $x\in A$ and select an appropriate $n$, which enables $x_n$ to converge to a point $x$ in $X$. Since the limit is unique, it must follow that $x=y$. Thus $x\in A$ and $A$ is closed.   If $A$ is a closed subset of $X$, then any Cauchy sequence of a point in $A$ is convergent in $X$ and hence converges to a point in $A$. Thus $A$ is complete.


this is my first question on StackOverflow and I am quite new to programming so please bear with me :) So I want to learn programming and I started with JAVA, the basics, classes, variables, methods and all that stuff. It went quite good until I stumbled over the term 'Interface'. I didn't understand it by what was written on  and I am finding myself now browsing the web to understand it but I don't seem to find the right, easily explained answer. I don't get the usage of interfaces... :(  I try to make an example:  So I know how to declare an interface and I know how to implement it into a class..  The interface:  interface motor {      void speedUp(int increment);  }   A class:  public class Bicycle implements motor {      int speed = 0;      void speedUp(int increment) {      speed = speed + increment;        }   }   So now I could use the interface of the Bicycle class by  Bicycle.speedUp(10);   But I don't understand what do I need the Interface for? Because I could use the method in the same fashion without having the interface. Even if I have more classes that use this interface, I'd still have to create the method speedUp individually in each class because the interface demands it so why not just leave it out in the first place? I hope you understand my problem and I am looking forward to your answers :)  Cheers

So lets say I have this interface:  public interface IBox {    public void setSize(int size);    public int getSize();    public int getArea();   //...and so on }   And I have a class that implements it:  public class Rectangle implements IBox {    private int size;    //Methods here }   If I wanted to use the interface IBox, i can't actually create an instance of it, in the way:  public static void main(String args[]) {     Ibox myBox=new Ibox(); }   right? So I'd actually have to do this:  public static void main(String args[]) {     Rectangle myBox=new Rectangle(); }   If that's true, then the only purpose of interfaces is to make sure that the class which implements an interface has got the correct methods in it as described by an interface? Or is there any other use of interfaces?


I got the following output when removing a kernel by dpkg --purge :   Removing linux-headers-3.13.0-112-generic (3.13.0-112.159) ... Removing linux-image-extra-3.13.0-112-generic (3.13.0-112.159) ... run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 3.13.0-112-generic /boot/vmlinuz-3.13.0-112-generic run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.13.0-112-generic /boot/vmlinuz-3.13.0-112-generic update-initramfs: Generating /boot/initrd.img-3.13.0-112-generic W: TMPDIR is mounted noexec, will not cache run scripts.  gzip: stdout: No space left on device E: mkinitramfs failure cpio 141 gzip 1 update-initramfs: failed for /boot/initrd.img-3.13.0-112-generic with 1. run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 1 dpkg: error processing package linux-image-extra-3.13.0-112-generic (--purge):  subprocess installed post-removal script returned error exit status 1 Removing linux-image-3.13.0-112-generic (3.13.0-112.159) ... Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.13.0-112-generic /boot/vmlinuz-3.13.0-112-generic update-initramfs: Deleting /boot/initrd.img-3.13.0-112-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.13.0-112-generic /boot/vmlinuz-3.13.0-112-generic Generating grub configuration file ... Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported. Found linux image: /boot/vmlinuz-4.4.0-71-generic Found initrd image: /boot/initrd.img-4.4.0-71-generic Found linux image: /boot/vmlinuz-4.4.0-67-generic Found initrd image: /boot/initrd.img-4.4.0-67-generic Found linux image: /boot/vmlinuz-4.4.0-66-generic Found initrd image: /boot/initrd.img-4.4.0-66-generic Found linux image: /boot/vmlinuz-4.4.0-64-generic Found initrd image: /boot/initrd.img-4.4.0-64-generic Found linux image: /boot/vmlinuz-3.13.0-115-generic Found initrd image: /boot/initrd.img-3.13.0-115-generic Found linux image: /boot/vmlinuz-3.13.0-113-generic Found initrd image: /boot/initrd.img-3.13.0-113-generic Found memtest86+ image: /memtest86+.elf Found memtest86+ image: /memtest86+.bin   No volume groups found done Purging configuration files for linux-image-3.13.0-112-generic (3.13.0-112.159) ... Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.13.0-112-generic /boot/vmlinuz-3.13.0-112-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.13.0-112-generic /boot/vmlinuz-3.13.0-112-generic Errors were encountered while processing:  linux-image-extra-3.13.0-112-generic  Why does it run out of space even when purging? It is not an inode issue in this case.  Note: There are other questions where error happens during dpkg --configure or when installing a kernel. It is more understandable that system runs out of disk space then, but in this case I am purging a kernel - a linux-image-extra package to be specific - by dpkg. There is no dependency problem in this case. For example in  a solution could be to purge kernel packages directly by dpkg, but the issue of this question produces an error when doing so.

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


Example:  The Stack Overflow question  asked in 2008 is marked as duplicate of  which was asked later (2010), shouldn't it be the other way around/a mechanism to prevent people from doing such silly things?

I have seen this many times, a question is being asked because a previous, duplicate question was asked and answered a few years ago and has no longer relevant answers.  The  is to edit the old question, or add new answers to it, but it is not always happening.  I was wondering, should I still mark it as duplicate and vote to close it? Or just leave it as is?


I have a noun that consists of two words ("impact parameter") that I am trying to turn into a compound adjective to describe a certain type of collision ("high impact parameter collision").  Where, if anywhere, should the hyphens go on this phrase?  The two choices I can't decide between are:   high-impact parameter collision high-impact-parameter collision

For example, "file system" and "related". Is it "file system-related"? It will appear as if it is a compound of "file" and "system-related", won't it?


In a bootstrap modal I have a file select input which I want to be fired automatically just by opening modal. I tried many many different approaches, but none of them worked for me.    UPDATE:

             <button id="close-modal-crop" type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
{{ heading_title }}

                     <input id="cropit-image-input" type="file" class="cropit-image-input custom" accept="image/*">   By opening modal, I want #cropit-image-input to be clicked automatically. I'd highly appreciate if you give me a hand.

I'd like to make a click event fire on an <input type="file"> tag programmatically.  Just calling click() doesn't seem to do anything or at least it doesn't pop up a file selection dialog.  I've been experimenting with capturing events using listeners and redirecting the event, but I haven't been able to get that to actually perform the event like someone clicked on it.


why IDE say me EXCEPTION at the line 247 of Register Activity of my class?  this is the line code:  Register Activity:  AppController.getInstance().addToRequestQueue(strReq, tag_string_req);   I must post all code about this class?  P.S.:I have this exception when i click on button "register"

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?


There are 2 close vote options that seem to say that a question belongs on SuperUser instead of StackOverflow. (I'm not sure what the options are on other SE sites.)     Closing > Off-Topic > "Questions about general computing hardware and software..."   and     Closing > Off-topic > Migration > belongs on superuser.com   What's the difference? Why do we have both?

Super User appears in both the main Off-Topic list and the Migration list of the close dialog. Is this a bug or intentional?  I also don't really understand why Server Fault appears in the main Off-Topic list and not the Migration list, apart from it being new.  Here:    and:


I live in a German speaking country but prefer watching movies/TV shows in English. The biggest reason is, in my opinion, the wrong translation of the word "you". In German there are two possible translations:   "Sie": formal, usually used when talking to an adult in a business relation or a child talking to an adult or talking to elderly people. In addition this is mostly combined with the family name: "Sie, Herr Schmied" = "You, Mr. Smith" "Du": informal, between children and friends, though in many companies nowadays also between coworkers. In addition this is mostly combined with the given name. "Du, Michael" = "You, Michael"   In German localizations "Sie" is used most of the time. And this just doesn't make sense to me. Like, I would never use "Sie" on a date or rarely someone at my age (mid 30s) I meet on the street. This was maybe common 50 years ago, but not today. With business customers it somehow is still expected, even if I don't like it. In my experience with communicating with US residents, the family name is rarely used and in emails the given name is used. Maybe I make a wrong link here and using he given name is considered formal in the US.  Is "Sie" the right translation for "you" in informal conversation (in movies/TV shows)?

Is there a reason why in so many English-language movies and TV series, whenever someone is speaking "German", they (actors, writers etc.) just don't care about if what they say is right or wrong? This can range from:    just minor grammatical errors e.g. "Schieß dem Fenster" in "Die Hard":                                rambling some made-up words and claiming them to be German e.g. "Lebenslangeschicksalssatz" in "How I met your mother"                                wrong German paired with a bad accent e.g. in "Scrubs"                                up to native German speakers talking complete nonsense e.g. Heidi Klum in HIMYM                                  I don't know if this is the same with other languages (for example there is a scene in Scrubs where the cast speaks Spanish, but there might be similar mistakes:                                 Do the creators and actors just not want to speak correct German and at least use correct German words, or is there simply no money in a $100,000,000 movie production to ask a native speaker to look over your script and maybe correct some of the lines?


I've got a particular answer that got downvoted a couple of times, for reasons I don't understand. I'm not particularly concerned about the odd point of rep (though for us low-rung ladder people, it all counts!), but I'm more bothered because I really don't understand what was wrong with the answer I gave. I can understand no votes, but for it to be actively downvoted has puzzled me.  Without the downvoter commenting to my answer, I'm left stuck without any further recourse. How can I tell who downvoted it?  Please note — I'm not a saddo looking to indulge in some pathetic tit-for-tat. I'm just puzzled because the question couldn't really have a "wrong" answer.  The question is , although I've since noticed it on another answer of mine too.

Is there a way to see who voted (upvotes and/or downvotes) on your answers and/or questions?


int array1[] = {1, 2, 3, 4, 5}; int array2[] = {6, 7, 8, 9};  int *arrays[] = {array1, array2};  How to get length of the array1 and array2 from arrays? (arrays[0] length and arrays[1] length)

First off, here is some code:  int main()  {     int days[] = {1,2,3,4,5};     int *ptr = days;     printf("%u\n", sizeof(days));     printf("%u\n", sizeof(ptr));      return 0; }   Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)?


I am going to Sweden. I got a tourist visa issued by the Swedish embassy. During my application, I chose "Sweden" as my first border entry. I am not sure if I could leave it blank. Now I am going to buy a ticket from Canada to Sweden and just figured that there is no direct flight from Canada to Sweden. Hence, it is necessary to have a stop in one another Schengen country (e.g., France, Netherlands, ...).  Will I face any problem at the border?

In case, if I get a multiple-entry Schengen visa in one of the embassies in Ukraine, Kyiv - should my first trip be to the country which issued the visa?  Any there any requirements of this sort? Does this condition vary depending on embassy which issued the visa?  What are the possible consequences on not visiting that country first? Does it somehow depend on country where the embassy is (i.e. non-Schengen and not EU members)?


I probably did not make the title correctly but please someone explain why I can't create prototype for person object? Only works when I put hit to Object.prototype chain.  const person = {   isHuman: false,   printIntroduction: function () {     console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`);   } };  //person.prototype.hit = function(){ //    console.log("hitting me"); //}  Object.prototype.hit = function(){     console.log("hitting me"); }  const me = Object.create(person);  me.name = "Matthew"; // "name" is a property set on "me", but not on "person" me.isHuman = true; // inherited properties can be overwritten  me.printIntroduction(); me.hit();   (UPDATE) . Why does THIS work?? Not sure what the differences are actually from this example but this code works.  function person {   isHuman: false,   printIntroduction: function () {     console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`);   } }();  person.prototype.hit = function(){      console.log("hitting me"); }  /* person.prototype.hit = function(){     console.log("hitting me"); } */  Object.prototype.hit = function(){     console.log("hitting me"); }  const me = Object.create(person);  me.name = "Matthew"; // "name" is a property set on "me", but not on "person" me.isHuman = true; // inherited properties can be overwritten  me.printIntroduction(); me.hit(); // expected output: "My name is Matthew. Am I human? true"   update 2  Ok, so I make it work like below but clearly prototype doesn't work the way I expected.. so I am clearly confused about prototype  function person(){     console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`); }  person.prototype.hit = function(){     console.log("hitting me1"); }  Object.prototype.hit = function(){     console.log("hitting me2"); }  const me = Object.create(person);  me.hit();   UPDATE 3.  thank you.. this is the explanation that I got from below.. thank you and this is clear now.  function person(){     console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`); }  person.prototype.hit = function(){     console.log("hitting me1"); }  Object.prototype.hit = function(){     console.log("hitting me2"); }  //const me = Object.create(person); const me = new person;  me.hit();

I'm not that into dynamic programming languages but I've written my fair share of JavaScript code. I never really got my head around this prototype-based programming, does any one know how this works? var obj = new Object(); obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test();  I remember a lot discussion I had with people a while back (I'm not exactly sure what I'm doing) but as I understand it, there's no concept of a class. It's just an object, and instances of those objects are clones of the original, right? But what is the exact purpose of this ".prototype" property in JavaScript? How does it relate to instantiating objects? Update: correct way var obj = new Object(); // not a functional object obj.prototype.test = function() { alert('Hello?'); }; // this is wrong!  function MyObject() {} // a first class functional object MyObject.prototype.test = function() { alert('OK'); } // OK  Also these  really helped a lot.


How to change the default desktop background? A list of background pictures are available in the preference window, but I want to make my own picture as a default wallpaper. What can i do?

I am about to ship a new 10.04 installed system to a customer. This is the 1st system that we are shipping with our preinstalled software and an additional hardware test platform, so I thought it would be a nice idea to have the desktop wallpaper include our company's logo.  What I want to do is just to add the logo to the default background image. the questions are:   Where are the set of backgrounds stored? What are the rules for creating a custom background from scratch? If I create a background from scratch, how do I add it to the system's background set (i.e., not just save it in the user's Pictures directory - I want it to be available to all future users of the machine)?


Hi I have a dataset where I have P number of predictors.  One of the predictors is "Color".  Color is always either "Green" or "Red". In the results of the glm call - which was btw - glm(target ~ color + age, data = d, family = binomial(logit)) -  only "colorGreen" is there and it is not statistically significant.  Why does "colorRed" not have a row in the results?  Edit:  I am not looking for general logistic regression help.  This question is not a duplicate for another question that is a general question. This is a specific question.

I'm struggling with the interpretation of a regression model where a categorial variable (5 levels) is dummy coded. Here is the result of my calculation in R:  Call: lm(formula = DV ~ Age + Gender + factor(Categorial) +  Continuous 1 + Continuous 2 + Continuous 3,  data = dat)  Residuals:  Min       1Q   Median       3Q      Max  -1.30058 -0.25326  0.00349  0.28123  1.49877   Coefficients:                       Estimate Std. Error t value Pr(>|t|)    (Intercept)           -0.42367    0.30694  -1.380  0.16842    Age                   -0.05949    0.02026  -2.936  0.00356 ** Gender                -0.01800    0.04828  -0.373  0.70952    factor(Categorial)2   -0.30625    0.12645  -2.422  0.01596 *  factor(Categorial)3   -0.03441    0.07752  -0.444  0.65736    factor(Categorial)4   -0.12603    0.09914  -1.271  0.20453    factor(Categorial)5   -0.08417    0.13269  -0.634  0.52630     Continuous 1           0.12080    0.04346   2.779  0.00575 ** Continuous 2          -0.06592    0.04383  -1.504  0.13354    Continuous 3          -0.06230    0.03475  -1.793  0.07392 .  --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  Residual standard error: 0.4259 on 336 degrees of freedom   (6 observations deleted due to missingness) Multiple R-squared:  0.1315,    Adjusted R-squared:  0.1057  F-statistic: 5.089 on 10 and 336 DF,  p-value: 6.353e-07   Ok. Age, Factor 2 of the categorial variable and the first continuous variable are significant predictors of the dependent variable. so far so good.   What I'm not understanding is:   The reference category of the dummy coded categorial variable is the intercept and the first category of the categorial variable. right? How do I interpret this?  When doing an anova with the categorial variable as a independent variable, this factor is a significant predictor. With the results of the linear model, one could conclude that this is only due to category 2, right? Can I test contrasts with this linear regression model (e.g. Category1 vs. Category2)? Should I include interactions?   I'd be glad for any help :-)


Let $\left\{B_n\right\}_{n=0}^{\infty}$ be an i.i.d. process, such that, for every $n\in\mathbb{N}\cup{0}$: $$\mathbb{P}[B_n=-1]=p \\ \mathbb{P}[B_n=+1]=q$$ Such that $p+q=1$. Let $\left\{X_n\right\}_{n=0}^\infty\subset\mathbb{S}$ be a markov chain, where $\mathbb{S}=\left\{i\right\}_{i=0}^K=\left\{0,1,...,K\right\}$ for some $K\in\mathbb{N}$, such that: $$X_n=X_{n-1}+B_{n}\qquad0<X_{n-1}<K \\ X_n=X_{n-1}\qquad\qquad \ \ X_{n-1}\in\left\{0,K\right\}$$ I drew the diagram of the process in order to see things more clearly:  Define the probabilty $\rho_{ij}$ for every $i,j\in\mathbb{S}\setminus\left\{0,K\right\}$ such that: $$\rho_{ij}\triangleq\mathbb{P}[\exists n>0 : X_n=j \mid X_0=i]$$ (In other words, $\rho_{ij}$ is the probability that the chain would somewhen visit the state {$j$}, given that the initial state is {$i$}. It is clear that if the initial state is $X_0=0$, then it is certain that the chain would visit the state {$0$} again, but never any other state. In other words, $\rho_{0k}=\delta[k]$ where $\delta$ is the delta of kronecker.) It is given that $p=q=1/2$. Find $\rho_{ij}$ for every $i,j\in\mathbb{S}\setminus\left\{0,K\right\}$.  I feel like I've tried everything. It seems that doing this straightforward is impossible, since the total number of paths that must be considered is too large. I understand that the expression would be different for the three cases $i=j,i>j$ and $i<j$. Finding $\rho_{ii}$ shouldn't be a problem if I knew $\rho_{ij}$ for $i>j$ and $i<j$, since: $$\rho_{ii}=p\rho_{i-1,i}+q\rho_{i+1,i}=[\rho_{i-1,i}+\rho_{i+1,i}]/2$$ And obviously $i>i-1$ & $i<i+1$. Thank you very much!

I have a simple and rather basic question regarding Markov Chains: let $B_{n}$ be an i.i.d process that gets the values $\{-1,1\}$ with probability of $\frac{1}{2}$. We define the following Markov Chain above $\{0,1,...,K-1,K\}$ states: $X_{n}=\begin{cases} X_{n-1}+B_{n}, & 0<X_{n-1}<K\\ X_{n-1}, & X_{n-1}=\{0,K\} \end{cases}$ The State Diagram for ($ p=\frac{1}{2} $):  I'm interested in finding the transition probability: $\rho_{ji}=P\{\exists n>0:X_{n}=i|X_{0}=j\}$ for $i,j\in\{1,2,...,K-1\}$ which is the probability that the process $X_{n}$ reaches state $i$ at some time $n$, given that the initial state was $j$. first, I was able to calculate: $\pi_{k}=\rho_{k0}=P\{\exists n>0:X_{n}=0|X_{0}=k\}=\begin{cases} 1-\frac{k}{K}, & 0<k<K\end{cases}$ which is the probability to reach state $0$ given that the initial state was at state $0<k<K$. this was done by assuming a general solution $\pi_{k}=a\lambda^{k}+b$, and solving an equation that has a relation between $\pi_{k,}\pi_{k-1,}\pi_{k+1}$, which gives $\pi_{k}=1-\frac{1-\lambda^{k}}{1-\lambda^{K}}$ where $\lambda={{\frac{p}{1-p}} }$. taking the limit $\lambda\rightarrow1$ , which suits our case, (in which $p=\frac{1}{2}$), gives the result for $\pi_{k}$ that I wrote above. I want to use $\pi_{k}$ to find an expression for $\rho_{ji}$ for $i,j\in\{1,2,...,K-1\}$. I argue that, in case $j>i$: $\rho_{ji}=P\{\exists n>0:X_{n}=i|X_{0}=j\}=P\{\exists n>0:X_{n}=0|X_{0}=|j-i|\}=\pi_{|j-i|0}$ from symmetry. which means moving (to the left) from state $j$ to $i$ (where $i,j\in\{1,2,...,K-1\}$), is equivalent to moving from state $|j-i|$ to state $0$. thus, by using the previous solution for $\pi_{k}$, one can find $\rho_{ji}$ for $j>i$ case: $\rho_{ji}=P\{\exists n>0:X_{n}=i|X_{0}=j\}=P\{\exists n>0:X_{n}=0|X_{0}=|j-i|\}=\begin{cases} 1 & |j-i|=k=0\\ 1-\frac{k}{K} & |j-i|=k\in\{1,..,K-1\}\\ 0 & |j-i|=k=K \end{cases}$ I somehow concluded also that $\rho_{ji}$ for $j<i$ should be equal to to the expression I got fior $j>i$ case, since intuitively, it sounds right to me. but turns out, according to an official solution (which wasn't really detailed), that the final answer for case $j<i$ (moving to the right) should be: $\rho_{ji}={ {\frac{j}{i}} }$ I can't figure out why, and I would be glad for some enlightenment. Note: it's possible that there is a mistake in the official solution, and I hope you can help me verify that.   Modification: Thanks to Misha's Answer, I figured out that the reason behind replacing $K$ with $K-i$ is the following: for example for $i<j:$ we are interested in defining a "new" Markov Chain depending on the distance we want to move from $j$ to $i$. (from right to left) for example if $K=6$ and we want to move from $state$ $j=5$ to $state$ $i=2$ , its equivalent to moving from $state$ $j=$$3$ to $state$ $i=0$ in a "smaller" Markov Chain that has the state $K-i$ at it's far right instead of $K.$ (which is the state we are never interested to visit, since our goal is to meet the wanted state which happens to be on the left). in other words, the Markov chain $\{0,...,K-i\}$ includes all the possible traveling distances to state $0$ starting from the state $\{K-i-1\}$, and the largest distance is moving $\{K-i-1\}$ $states$ down to state $zero$, which is equivalent to the largest traveling distance from $state$ $j=5$ down to $state$ $i=2$, which is $\{j-i\}$.


I am facing an issue in if statement for below code. I am not able to log into if statement even with correct condition. Is my syntax correct?  String NicotineProduct="Not in the last 5 years"  if (NicotineProduct=="No, Never"||NicotineProduct=="Not in the last 5 years"||NicotineProduct=="Not in the last 3 years")  {         if (rateclass=="Pref Best No Nicotine")              rateclassval=1;     else if (rateclass=="Pref No Nicotine")            rateclassval=2;     else if (rateclass=="Select No Nicotine")            rateclassval=3;     else if (rateclass=="Standard No Nicotine")            rateclassval=4;  }

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


I have a very simple question about nested for loops in Python (perhaps applicable to other languages).   Here's a minimal example:   my_array = [[0]*10]*10 k = 0 for i in range(10):     for j in range(10):         my_array[i][j] = k         k += 1    After executing these lines, I would expect my_array to look like a matrix with the digits 0 through 99 written out left to right top to bottom.  Instead my_array looks like this:  [[90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99],  [90, 91, 92, 93, 94, 95, 96, 97, 98, 99]]   Somehow it seems k is only being evaluated according to its values on the last run of the outermost i loop.  Does anyone understand what Python is doing here? Using the product function from ittertools produces (as the documentation makes clear) the same result. Also, replacing range(10) with either a tuple or a list of the digits 0 through 9 produces the same result.

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


I have a a file containing about 20 million sentences, how can I extract 2 million sentences out from it?  I thought about using the split command like this "split -l 2000000 sub2016", but then it will create a series of texts, while I just need one.  So how can I specify it? Thank you!

What's a good way of extracting say, lines 20 -45 out of a huge text file. Non-interactively of course!


Professor McGonagall was already getting on with years the the Original HP series.  From a person who has not read Cursed Child yet, I'm only reading it from here    And she's able to live for 19 years, without retiring...  And also Dumbledore is older than dirt,    With Elphias Doge, and Professor something, who supposedly tested Dumbledore on the OWL's (I think, correct me if I'm wrong).  And JKR can simply not be that bad at math(s).

In the Harry Potter series is it clear that magically-inclined individuals (witches/wizards) will live to be considerably older than their Muggle counterparts? From the question , it is given that Dumbledore was roughly 115 years old when he died, and at that age he hardly seemed ready to kick the bucket naturally.  With that in mind, how old will a wizard typically live to be, barring accidents or murder?


I need to permanently increase network latency in approximately 100ms, without losing packets.  Reason: On a certain server and internet game my ping is too much lower than the other people playing it. I have 15ms, when average is 150ms which gives me cheater-like advantages.  So also out of curiosity I'm looking for ways to increase my ping while keeping connection stable. What are my options if any?  I thought about VPN services, but it seems like a bad option since games use UDP?  Is there any router/software that would assist me on this?  I'm on windows.


I often find myself writing see Figure~\ref{fig:figname}, below or see Figure~\ref{fig:figname}, above, or similar phrases.  Is there a way to make LaTeX automatically decide between "above" and "below" depending on the location where the figure is rendered?

Is it possible to automatically include a reference to the position of a labeled object (Table, Figure) in text? By this I mean the following:  Say I have labeled a figure in chapter 1:  \label{fig:one}   Then I refer to it in text by using:  See Figure~\ref{fig:one}   Which produces "See Figure 1.1" as desired. I'd like to be able to have it produce: "See Figure 1.1, above" or "See Figure 1.1, below", automatically detecting whether to produce "above" or "below" depending on whether the figure will be placed above that position on the final page.


I'm running a script within a script, release.sh and caller.sh (caller.sh calls release.sh). Both are bash.  release.sh contains a bunch of conditions with 'exit 1' for errors.   caller.sh contains a line that goes "./release.sh", then a checks for the exit code of release.sh - if $? is greater than 0 then echo "release.sh screwed up" and exits.  ./release.sh         if [ $? -gt "0" ] ; then             echo "release_manager exited with errors, please see the release log."             exit 1         else              echo "release manager is done."          fi   Recently I've decided to log release.sh, and so the line in caller.sh goes:   ./release.sh 2>&1 | tee release.txt   Because of the pipe, $? is the exit code of 'tee release.txt' , which always comes out as 0, regardless of the previous command :-(  I have to check for release.sh errors and stop the caller from proceeding, but I also really need that log.   Is there a way to get the exit code of the command before last? Or a different way to log the release script in the same command?  I'm not really in charge of release.sh, I'd rather not change it.

I have two processes foo and bar, connected with a pipe:  $ foo | bar   bar always exits 0; I'm interested in the exit code of foo. Is there any way to get at it?


In my laptop I have first installed Windows 7. Then, installed Ubuntu 11.10. Now my laptop contains two Operating Systems. I don't have internet connectivity in home. But I have Ubuntu 14.04 ISO with me,   i need to upgrade Ubuntu 11.10 with Ubuntu 14.04 without uninstalling Windows 7 and Ubuntu 11.10  . How to achieve this...  please help..am new one to Ubuntu.

I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please?


I think this is a basic question but really I just need a definite starting point. I am working in R. I have a dataset as follows  rowid    TimePoint1   TimePoint2    TimePoint3    TimePoint4   TimePoint5   etc. 1          54            34           55           74             474     2          36            63           83           344            636     3          151           61           1643         34             976 etc.   (There are actually 10 TimePoints and hundreds of rows)  I want to basically create a best fit line (likely non-linear) which I can then compare to another group with the same dataset structure.  I think I really need to know what this type of analysis might be called- firstly to create the best fit (is it just regression?) and then to compare with another group.

I have a question related to modeling short time-series. It is not a question , but how. What method would you recommend for modeling (very) short time-series (say of length $T \leq 20$)? By "best" I mean here the most robust one, that is the least prone to errors due the fact of limited numbers of observations. With short series single observations could influence the forecast, so the method should provide a cautious estimate of errors and possible variability connected to the forecast. I am generally interested in univariate time-series but it would be also interesting to know about other methods.


I already asked If there exists an injective function $f:\mathbb{R}^5\rightarrow\mathbb{R}^4$ and I found that it exists a such function:   Now, I would like to know If there exist such an injective linear map. I was trying to find out but I am unable. In think it does not exists because of the difference between dimmnsions but I am really unsure.  Please help me. Thank you!!!!

Let $L:\mathbb{R}^n \rightarrow \mathbb{R}^m$ be a linear transformation such that $m<n$. What does this tell you about injectivity and surjectivity?  I can't really create a (counter) argument against any of these alternatives:   $L$ is injective $L$ is surjective $L$ is not injective $L$ is not surjective   My intuition says that one could find examples where $L$ is both injective and/or surjective, but not for all inputs outputs.


Being inspired by , I've wondered if the infinite series below may be expressed as an intregral. I'm very curious about that.   $$2\sum_{k=1}^{\infty}\frac{(2k-1)^2-1}{(2k-1)^4+(2k-1)^2+1}$$  I'd appreciate your feedback here. How should I ponder over this case as a simple student? Where should I start from and what techniques I need to think of? Thanks!

How to find $$\sum_{k \text{ odd}} \frac{2(k^2-1)}{k^4+k^2+1}$$  we find $\displaystyle\sum_{k=1}^{\infty} \frac{2(k^2-1)}{k^4+k^2+1}=1$ and we know that $\displaystyle\sum_{k \,\text{odd}} + \sum_{k \,\text{even}}=1.$ Can we use this information to find sum? Or, maybe we can find it on other way?  We can say that our sum is equal to $$\color{red}{2}\sum_{k=1}^{\infty}\frac{(2k-1)^2-1}{(2k-1)^4+(2k-1)^2+1}=\sum_{k=1}^{\infty} \left(\frac{1-4k}{4k^2-2k+1}+\frac{4k-3}{4k^2-6k+3}\right),$$ but I don't think we can see something from that.  EDIT: Actually, Wolfram find that $$2\sum_{k=1}^{\infty}\frac{(2k-1)^2-1}{(2k-1)^4+(2k-1)^2+1}=\pi \text{sech}\left(\frac{\sqrt{3} \pi}{2}\right).$$ It's pretty nice closed form.


Tried with apt autoremove, apt purge, apt-get -f install and few more. My present kernel version is 4.15.0-99 and old versions are {45,72,96}. As my terminal says I need little space on my boot for cleaning up and I have no space!

I have 200 MB assigned for the /boot partition.  Whenever I try to update the kernel, I receive an error message that basically states /boot is full.  What can I do to cleanup /boot and remove/backup the older kernels?


I was trying to trying to create a text curve in my language( ML-IN(malayalam)) and it didn't even show up please anyone know how to make it work?

How can I add text with non Latin characters? I'd like to get text in other languages like Arabic, Russin (Cyrilic), Japanese, Chinese, Malayalam among others, but I get rectangles instead of Arabic letters.


In the part where open source code used is mentioned, Butterknife appears twice with different licenses and creators.     App Version: 1.0.89

Butterknife appears twice in the OSS attribution list of the Android app (v1.0.85). Based on the links, the second one should be JMustache.


I deleted a profile yesterday. The system claimed it was to be deleted in 24 hours. However, I see the following message today.     This account is scheduled to be deleted 5 mins ago. To cancel deletion, click here.   Why the account isn't deleted on time? 5 mins after the deadline?

How can I delete my Stack Exchange account(s)? Also,  What happens to my content? Can I request it be deleted as well? What if I'm suspended, rate-limited, or banned from posting questions or answers? What will happen to my votes? Will other users be impacted? Why wasn't my account deleted immediately after the timer expiring? What will happen to my pending bounties and close, reopen, delete, or undelete votes? I want my account deleted on all Stack Exchange sites. How do I do this? Will my profile on chat be removed once I delete my site account?   For more information, see "" in the .


I am a programmer who used to constantly copy directory of a file from its "Get Info" menu. Since Yosemite, the original pure path is replaced with a "user-friendly" kid-version directory, which cannot be copied. Like this.    Is there a workaround for this?

What's a quick way of copying the path to the directory that's currently open in Finder?   Copying that path is very easy in Linux and Windows file managers - you just need to copy it from the address bar. I don't see a corresponding option in Finder.


I have a weird issue I've been strugling with for well over a year now...  I have 6GB RAM, but Windows works like it's more like 2GB. Windows reports that I have 6GB without problems, but right now for instance, if I sum the memory of all processes running, I get around 300MB of used RAM. Still, Windows claims I have used 73% of the physical RAM.  In other words, I only have 27% free of my 6GB, without ANY applications running (only small background apps/processes).  See this screenshot that explains the problem. In this case I have many apps running, but combined, they use less than 1GB memory. Stil, Windows reports that 96% of my memory is used, and behaves accordingly (apps crashing, memory warnings etc).

I have a fresh install of Windows 7, and my RAM in normal startup goes up to 2.5GB. I looked at Task Manager, and there's at least 1.5GB missing from there and in Resource Monitor as well. There's no indication of what's using that RAM. Can someone tell me how I can find out what's consuming my memory? I believe it's a virus, but none of the free antivirus programs tracked it down.   I added the pictures below. If this is normal usage of Windows 7 as some answers imply, then I don't get this at all.   P.S. My Windows 8 Installation was running below 2.5GB, actually it was 1. something, until recently that I transferred some files from another computer which had the same problem that mine has now. I deleted Windows 8 and installed Windows 7, since I would do that anyway, and now I'm getting high memory usage in Windows 7 as well.   (Click images to enlarge)


Can you give an example of non-commutative ring $R$ such that every ideal is two sided?

I was thinking about the following problem:     Suppose R is a ring s.t. every left ideal is also right. Is R commutative?   This actually continues the easier question:     Suppose G is a group whose all subgroups are normal. Is G commutative?   The answer to the latter is negative, since one can take the quaternion group of order 8.  Edit: One can indeed take a division ring as an counterexample. I am looking for something more interesting, in particular with some proper ideals.  Thanks


I have a:  var selectedDates = new Dictionary<string, string>(); selectedDates.Add("2014-06-21", DateTime.Now.ToLongDateString()); selectedDates.Add("2014-07-21", DateTime.Now.AddDays(5).ToLongDateString()); selectedDates.Add("2014-08-21", DateTime.Now.AddDays(9).ToLongDateString()); selectedDates.Add("2014-09-21", DateTime.Now.AddDays(14).ToLongDateString());   How can I loop trough items without knowing the key?     For example I want to get the value of the item[0]   If I do:  var item = selectedDates[0].value; // I get an error

I've seen a few different ways to iterate over a dictionary in C#.  Is there a standard way?


At my school we are starting to implement Office 365 for our students. We are working on basis of a bring-your-own-device strategy and will meet all kinds of devices and OS's. Office 365 comes with a built-in cloud feature, which can be synced to a newer Windows machine. Is there a possibility to sync to Ubuntu or Lubuntu machine, as it is possible with fx Dropbox? Thanks for helping. Armin

Microsoft OneDrive Business/Office 365 Pro offers 1 TB of cloud storage but unfortunately there has never been a method to sync it on Linux.


I am getting null pointer exception at line 9 of my code I am fairly new to java can someone tell me the concept and mistakes I am doing.  public static void main(String[] args) {     Certificate certificate1= new Certificate(60,"cnexirk","cbnifms",77);     Certificate certificate2= new Certificate(45,"gphspvq","pqjbhmz",62);     Certificate certificate3= new Certificate(41,"nfpxsmp","vimiopu",89);     Certificate certificate4= new Certificate(95,"ionouca","bsbknpx",38);     Certificate certificate5= new Certificate(39,"yhzrafu","itnbskb",44);     Certificate[] objArray={certificate1,certificate2,certificate3,certificate4,certificate5};     Certificate[] objResultArray1=getEven(objArray);     for(Certificate certificate:objResultArray1){         System.out.println(certificate.getId()+" " + certificate.getTitle()+" " + certificate.getDate()+" " + certificate.getRank()+" ");     }   public static Certificate[] getEven(Certificate[] cer) {     Certificate[] objresult=new Certificate[cer.length];     for(int i=0;i<cer.length;i++)     {         if(cer[i].getRank()==77)         {             objresult[i]=cer[i];         }     } return  objresult; }   } `

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?


$$\lim_{h\to 0}\frac{\sin(x+h)-\sin(x)}{h}$$ Using the fact that: $$\lim_{x\to 0}\frac{\sin(x)}{x}=1.$$  Thank you in advance for any help.

One of the first things ever taught in a differential calculus class:   The derivative of $\sin x$ is $\cos x$. The derivative of $\cos x$ is $-\sin x$.   This leads to a rather neat (and convenient?) chain of derivatives:   sin(x) cos(x) -sin(x) -cos(x) sin(x) ...   An analysis of the shape of their graphs confirms some points; for example, when $\sin x$ is at a maximum, $\cos x$ is zero and moving downwards; when $\cos x$  is at a maximum, $\sin x$ is zero and moving upwards.  But these "matching points" only work for multiples of $\pi/4$.  Let us move back towards the original definition(s) of sine and cosine:  At the most basic level, $\sin x$ is defined as -- for a right triangle with internal angle $x$ -- the length of the side opposite of the angle divided by the hypotenuse of the triangle.  To generalize this to the domain of all real numbers, $\sin x$ was then defined as the Y-coordinate of a point on the unit circle that is an angle $x$ from the positive X-axis.  The definition of $\cos x$ was then made the same way, but with adj/hyp and the X-coordinate, as we all know.  Is there anything about this basic definition that allows someone to look at these definitions, alone, and think, "Hey, the derivative of the sine function with respect to angle is the cosine function!"  That is, from the unit circle definition alone.  Or, even more amazingly, the right triangle definition alone.  Ignoring graphical analysis of their plot.  In essence, I am asking, essentially, "Intuitively why is the derivative of the sine the cosine?"


I know that in general, the definite article "the" does not usually precede proper nouns:  Verizon introduced two new phones today (not "The Verizon")  but it gets trickier when the proper noun is an abbreviation that stands for a phrase that would require preceding with "the", if it were stated in an unabbreviated form.  "BBC added two new shows" vs. "The BBC added two new shows" (British Broadcasting Corporation) "MBTA added two new trains" vs. "The MBTA added two new trains" (Massachusetts Bay Transportation Authority) "Caltrans added two new exit ramps" vs "The Caltrans added two new exit ramps" (California Department of Transportation) "Win32 API added two new functions" vs "The Win32 API added two new functions" (Windows 32-bit API) "WinAPI added two new functions" vs "The WinAPI added two new functions" (Windows API) "DOD added two new aircraft carriers" vs "The DOD added two new aircraft carriers" (Department of Defence) "NATO added two new offices in Poland" vs "The NATO added two new offices in Poland" (North Atlantic Treaty Organization) "NYPD added two new task forces" vs "The NYPD added two new task forces" (New York [City] Police Department)  Can anyone help provide guidance for which form to use, depending on how it is used? As far as I can tell:  Subject -- not sure; see my examples above Direct object -- not sure (example: "I love NYPD" vs "I love the NYPD") but "the" sounds better Indirect object -- not sure (example: "Someone gave NYPD two new cars" vs "Someone gave the NYPD two new cars") but "the" sounds better Adjective forms -- do not use "the" (example: "Two NYPD officers", "I like MBTA trains") Object of a preposition -- not sure (example: "Two officers from NYPD" vs "Two officers from the NYPD"; "Two functions in WinAPI" vs "Two functions in the WinAPI") but "the" sounds better When the noun is pronounceable like "Caltrans" or "NATO" then it sounds wrong to add "the" in front of it

I'm wondering when to use or not to use the definite article, when using acronyms or initialisms in a sentence. Is there a rule for this, or does it depend on the context?  For example, let's look at some example sentences DDR  = detailed design review.  NASA is planning to launch the final shuttle soon (no article) The FBI shut down this website (article) ESA is a full partner in the ISS (no article, article) The project was cancelled at the DDR. (article)  What confuses me is that if NASA or ESA would be written in full, the article would be necessary.


How can I install Java 8 along with Java 9... I want both.   Please tell how to set both of their path so that I can use both of them.

We have a couple of applications running on Java 5 and would like now to bring in an application based on Java 6. Can both java versions live together under Windows?   Is there any control panel to set the appropriate Java version for different applications, or any other way to set up, what version of Java will be used to run that particular application?


My phone has problem and I get the following error for many programs:  Now, I want to refactor my Android, But I need to save my Memo's information.  Where are my Memo's information? UPDATE: I think my data exists on my disk, Because when I open my memos, I see the following data:  I found ShareMemo directory, But it doesn't contain of my information.

Could you list all possible directories where Android apps may store data, providing description what kind of data are stored in each directory?


We have a line segments with length $l$ then you choose two random points and cut it from these points so that we  have three piece of line segments.  What is the probability that these piece constitute a triangle ?    We need to use triangle inequality but I could not manage it. Thanks.

Randomly break a stick (or a piece of dry spaghetti, etc.) in two places, forming three pieces.  The probability that these three pieces can form a triangle is $\frac14$ (coordinatize the stick form $0$ to $1$, call the breaking points $x$ and $y$, consider the unit square of the coordinate plane, shade the areas that satisfy the triangle inequality edit: see comments on the question, below, for a better explanation of this).  The other day in class*, my professor was demonstrating how to do a Monte Carlo simulation of this problem on a calculator and wrote a program that, for each trial did the following:   Pick a random number $x$ between $0$ and $1$.  This is the first side length. Pick a random number $y$ between $0$ and $1 - x$ (the remaning part of the stick).  This is the second side length. The third side length is $1 - x - y$. Test if the three side lengths satisfy the triangle inequality (in all three permutations).   He ran around $1000$ trials and was getting $0.19$, which he said was probably just random-chance error off $0.25$, but every time the program was run, no matter who's calculator we used, the result was around $0.19$.  What's wrong with the simulation method?  What is the theoretical answer to the problem actually being simulated?  (* the other day was more than $10$ years ago)


I am analysing data of covid19 patients and trying to determine which illnesses could be detrimental for the outcome. In the original data table there are three possible outcomes - 1 (recovered), 2 (dead) and 3 (transferred to another department). I reduced the data frame by filtering out the patients with the 3rd outcome. There are approx. 60 patients with the third outcome out of 230. Almost all the predictors are factorial. When I do the binomial regression using glm() the coefficient for a variable x is 3.078e+00 with p-value 7.16e-05. However when I am doing multinomial regression using function multinom() for the same variable the coefficient is 1e+00 with p-value 4.308713e-02. What could be the problem? Which result is more reliable?

I am analysing data of covid19 patients and trying to determine which illnesses could be detrimental for the outcome. In the original data table there are three possible outcomes - 1 (recovered), 2 (dead) and 3 (transferred to another department). For the binomial regression (glm) I reduced the data frame by filtering out the patients with the 3rd outcome. There are approx. 60 patients with the third outcome out of 230. Almost all the predictors are factorial. When I do the multinomial regression using multinom() the coefficient for a variable x ( the variable is factorial, takes values of 1 / 0) is 1.078e+00 with p-value 1.227e-04. However when I am doing binomial regression using function glm(family = "binomial") for the same variable the coefficient is 21.435 with p-value 7.163e-05. Also, the confidence interval for the coefficient in the binomial model is very wide (approx. 3 - 52). The same goes with the multinomial model, the confidence intervals are 1e+00 - e+01 wide. What could be the problem? Which result is more reliable?


while working on performance sensitive code I discovered that HashSet should offer constant time performance for its add, remove, contains and size methods as long as the hash-function returns unique hashes for the elements in the set ().  When executing the following code, I discovered that this constant time performance for the add method does not hold true. The following code should round in roughly double the time compared with the runtime of executing it with numberOfELements = 10.000.000. But it needs roughly 3-4 times as long.  HashSet<Integer> myHashSet; int numberOfElements;  //Warm-up code numberOfElements = 10000000; //10 Mio Elements myHashSet = new HashSet(540000000); //Create HashSet with large enough initial capacity to avoid resize operations for (int i = 0; i < numberOfElements; i++){    myHashSet.add(i); //Add random element }  //First benchmark numberOfElements = 5000000; //5 Mio Elements myHashSet.clear(); //Clear HashSet long startTime = System.nanoTime(); //Save start time for (int i = 0; i < numberOfElements; i++){    myHashSet.add(i); //Add elements } System.out.print("Set filled with " + myJournalPoC.SFA_Journal.size() + " records in "); System.out.println((System.nanoTime() - startTime)/1000000000 + "s");  // Second benchmark numberOfElements = 10000000; //10 Mio Elements myHashSet.clear(); //Clear HashSet long startTime = System.nanoTime(); //Save start time for (int i = 0; i < numberOfElements; i++){    myHashSet.add(i); //Add elements } System.out.print("Set filled with " + myJournalPoC.SFA_Journal.size() + " records in "); System.out.println((System.nanoTime() - startTime)/1000000000 + "s");  // Third benchmark numberOfElements = 20000000; //20 Mio Elements myHashSet.clear(); //Clear HashSet long startTime = System.nanoTime(); //Save start time for (int i = 0; i < numberOfElements; i++){    myHashSet.add(i); //Add elements } System.out.print("Set filled with " + myJournalPoC.SFA_Journal.size() + " records in "); System.out.println((System.nanoTime() - startTime)/1000000000 + "s");  // Third benchmark numberOfElements = 40000000; //40 Mio Elements myHashSet.clear(); //Clear HashSet long startTime = System.nanoTime(); //Save start time for (int i = 0; i < numberOfElements; i++){    myHashSet.add(i); //Add elements } System.out.print("Set filled with " + myJournalPoC.SFA_Journal.size() + " records in "); System.out.println((System.nanoTime() - startTime)/1000000000 + "s");   I'd really appreciate to know the root cause for this behavior.  EDIT: I added the code to measure performance in the example above.

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