A command-line clipboard copy and paste utility?

In Windows I used command-line clipboard copy-and-paste utilities...      pclip.exe and gclip.exe     These were UnixUtils ports for Windows (but they only handled plain text). There were a couple of other native Windows utilities which could write/extract any format.    I've looked for something similar in Synaptic Package Manager, but I can't find anything.    Is there something there, that I've missed? ... or maybe this is available in Bash scripting?    The type of utility I'd like will be able to read/write via std-in/std-out or file-in/file-out, and handle Unicode, Rich Text Format, picture, etc. clipboard formats...    NB: I'm not after a clipboard manager.


What is the difference between upstream and downstream when referring to who to go to as a developer?

What is the difference between upstream and downstream when referring to who (or where) to go to as a developer or packager?


Text mining of machine logs to find correlation between errors in R

I've with me 50 MB data from a machine consisting of event logs such as device status, warning and error. I wish to perform text mining on the same to find correlation between errors i.e. one error could trigger another in future and take a prescriptive action on it. I've used hierarchical clustering in R to generate a dendrogram but the result couldn't yeild expected insight. Hence, I've planned to perform Apriori Algorithm on the same. My queries are:  Is Hierarchical Clustering suggested to find such correlations? Is Apriori an apt algorithm in such situation and why? Or, is there any other approach to solve this problem?  Any help would be appreciated.  Thanks


Find the limit of the following sequence. (Real Analysis)

Find the limit of the following sequence.  $$a_n = \frac{\sqrt[n]{(n+1)(n+2)...(2n)}}{n}$$  I tried couple of methods: Stolz, Squeeze, D'Alambert. But I can not seem to make a conclusion on the limit.


I have to show for all x,y ∈ ℝ that ||x| - |y| ≤ |x-y| I know that |x| = |x - y + y| ≤ |x - y|+|y| Does it suffice to put in numbers now or how would I proof that?


My original list is changing when using append or extend

I would like to know if this is normal behavior for Python. Code is:  >>>abcd = [["a","b","c","d"],[1,2,3,4]] >>>testlist = []   then  >>>testlist.extend(abcd)  or if I use:  >>>for item in abcd:     testlist.append(item)   the result of calling testlist is the same, which is perfectly fine:  >>>testlist [['a', 'b', 'c', 'd'], [1, 2, 3, 4]]   but then when I do something with 'testlist' the change appears also in 'abcd'  >>>testlist[0].append("anything") >>>testlist [['a', 'b', 'c', 'd', 'anything'], [1, 2, 3, 4]] >>>abcd [['a', 'b', 'c', 'd', 'anything'], [1, 2, 3, 4]]    It is making me crazy. How should I proceed without changing original list and not making copies of it every time I need to pull some data from it. Thank you.


When should the word "NOW" be used in a sentence.......?

Consider the following 2 sentences:-   "Now the application is working fine". "The application is working fine now".   Which one is grammatically correct and why?


How can I get the list of ldap users without being sudo?

I have non-sudo ssh access to a server of which I want to know the list of users, I think the server is using ldap because:  -bash-4.2$ cat /etc/nsswitch.conf # /etc/nsswitch.conf # # Example configuration of GNU Name Service Switch functionality. # If you have the `glibc-doc-reference' and `info' packages installed, try: # `info libc "Name Service Switch"' for information about this file.  passwd: files ldap group: files ldap shadow: files ldap  hosts: files dns networks: files  protocols: db files services: db files ethers: db files rpc: db files  netgroup: nis   but:  -bash-4.2$ cd /etc/sssd/ -bash: cd: /etc/sssd/: No such file or directory   Please note neither of /etc/passwd, ls -lsa /varor getent passwd is giving the list I want (they don't even include my own username)  So, does anyone have any idea on how I can get the list of usernames and ids of this server?  -bash-4.2$ lsb_release -a No LSB modules are available. Distributor ID: Debian Description:    Debian GNU/Linux 7.11 (wheezy) Release:    7.11 Codename:   wheezy


python2 and OpenSSL don't play together on Kali - how to fix?

I have a Kali Linux distrubution which is Kali GNU/Linux Rolling (currently version 2017.3) on amd64. I'm keeping it regularly up to date and have not meddled with system files or the package management. Yet, some time ago python2 and OpenSSL stopped playing together. In the beginning this was simply odd but now it is a major nuisance. E.g. a simple call like this fails:  # pip /usr/lib/python2.7/dist-packages/cffi/model.py:532: UserWarning: 'point_conversion_form_t' has no values explicitly defined; guessing that it is equivalent to 'unsigned int'   % self._get_c_name()) Traceback (most recent call last):   File "/usr/bin/pip", line 9, in <module>     from pip import main   File "/usr/lib/python2.7/dist-packages/pip/__init__.py", line 21, in <module>     from pip._vendor.requests.packages.urllib3.exceptions import DependencyWarning   File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 64, in <module>     vendored("cachecontrol")   File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 36, in vendored     __import__(modulename, globals(), locals(), level=0)   File "/usr/share/python-wheels/CacheControl-0.11.7-py2.py3-none-any.whl/cachecontrol/__init__.py", line 9, in <module>   File "/usr/share/python-wheels/CacheControl-0.11.7-py2.py3-none-any.whl/cachecontrol/wrapper.py", line 1, in <module>   File "/usr/share/python-wheels/CacheControl-0.11.7-py2.py3-none-any.whl/cachecontrol/adapter.py", line 4, in <module>   File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/__init__.py", line 52, in <module>   File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/packages/__init__.py", line 59, in <module>   File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/packages/__init__.py", line 32, in vendored   File "/usr/share/python-wheels/urllib3-1.19.1-py2.py3-none-any.whl/urllib3/contrib/pyopenssl.py", line 47, in <module>   File "/usr/lib/python2.7/dist-packages/OpenSSL/__init__.py", line 8, in <module>     from OpenSSL import rand, crypto, SSL   File "/usr/lib/python2.7/dist-packages/OpenSSL/SSL.py", line 112, in <module>     if _lib.Cryptography_HAS_SSL_ST: AttributeError: 'FFILibrary' object has no attribute 'Cryptography_HAS_SSL_ST'   Sifting thorough various search engine results I found out that this seems to be a known incompatibility problem, but apparently there is no tangible clean solution. What puzzles me is that how can that happen in an actively maintained distro? (In fact, a collegue with the same setup does not have this problem.)  Is there a simple way to repair/fix this without reinstalling the whole distribution?  The installed versions are python/kali-rolling 2.7.14-1, python-openssl/kali-rolling 16.2.0-1 and python-cffi/kali-rolling 1.9.1-2.


Term describing emotional agreement with an argument regardless of the validity of the argument itself?

I was wondering if there is a word that describes when someone emotionally agrees with someones argument regardless of whether the argument actually is a valid argument or not.  For example a fan of sports team X might get excited and agree with someone's argument that "Sports team Y is terrible" regardless of any evidence they give to support that claim.  The online Cambridge definition of 'jingoism' is close, but describes only nationalistic arguments.  It's not a potshot, or straw man because those describe the argument and also because the word I'm looking for could allow for a rigorous, and true argument, but the reason the person agrees with it is not based on the argument but their allegiances.


I have a code generation tool that creates a single cs file with some interfaces, classes and a namepsace (with other classes in it). Some of the classes are defined outside of the namespace. What I would like to do is automatically strip away the namespace (and everything in it) and one of the classes (along with its associated attributes).  I know I could potentially write a regex expression to do this but I'm hoping there is some tool that understands the layout of the CS file (as a tree) so I can tell it which parts I want to prune away.


Time is considered to be a dimension, and we are moving at certain rate in one direction in time. What force makes us move in time? I mean it must be ether time moving or us moving in time so there has to be some force that 'pushes'/'pulls'? Was this 'time inertia' acquired during big bang, or nothing is moving and I am just being silly?


What is the etimology of word History? Is it in English word His Story, or is this only another fancy coincidence?


Is there a term for negligent spelling of words such as 'you' as 'u'?

The age of texting and instant messaging as we all know has created a phenomenon of using shorter versions of words to save on keystrokes. On tiny keypads or phone buttons this obviously can be a time saver. However, in a medium where these shortcuts are not expected (for example, this very Q&A site collection), I find it aggravating and annoying that someone cannot be bothered to type two extra characters for word substitutions such as "u" (you), "r" (are), and "4" (for).  I sometimes want to refer to this activity as something other than "lazy spelling" or "texty-speak..." Is there a term for this type of lazy word substitution?


How would one perform an $N$-body simulation in General Relativity (GR) for something like galaxy formation or galactic dynamics?  Suppose one wants to simulate the rotation curve $v(r)$ for galaxies with an $N$-body simulation, and wants to do it in the framework of GR / the Einstein equations.


How can I combine CPU & GPU Graphics for better performance?

Can I "combine" the power of my GPU with my CPU to get more FPS in games and more power for programs ?   CPU: Intel i5 4690K which is OC'd to 4.3Ghz with the box cooler GPU: AMD Radeon HD 7750 Saphire 1GB GDDR5 Edition which is OC'd with memory at 1130Mhz and GPU at 820Mhz, these frequencies are achieved while gaming. My MOBO is an Asus Z97-K The CPU has integrated graphics.


Generalizations of the quadratic formula

The quadratic formula can be used to find the roots of any quadratic polynomial of the form $ax^2 + bx + c$:  $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$  The derivation is simple enough and uses a technique called completing the square.  Is there a formula to solve cubic equations of the form:  $$ax^3 + bx^2 + cx + d$$  Or a general formula to solve an $n$th degree polynomial?  EDIT: According to the answers below, and some mathematicians, such a formula isn't possible. But why is that? I mean, consider an $n$th degree polynomial $p(x)$ with roots $r_1, r_2, \dots, r_n$:  $$p(x) = ax^n - \left(\sum r_i\right)ax^{n-1} + \left(\sum_{i, j} r_ir_j\right)ax^{n-2} + \dots+(-1)^n(r_1r_2\dots r_n)$$  We have $n$ equations with $n$ unknowns, surely this can be solved using a general algorithm?


Is my PHP SQL query safe from SQL injection?

I would like to know if my query is safe from an SQL injection.  Below is the PHP Code  $orderid = mysql_real_escape_string($orderid); mysql_query("SELECT * FROM orders WHERE id =\"".$orderid."\"");     Also   If the end user can change the order ID to what they wanted, what could they do here as worst case scenario?


Let $A$ be a subset of the domain of a function $f$. Why $f^{-1}(f(A)) \not= A$. I was not able to find a function $f$ which satisfies the above equation. Can you give an example or hint. I was asking for an example function which is not addressed


Double-clicking my Apple earbud remote brings up Siri

With macOS Sierra pushing Siri as a very cool new feature, the behaviour of my (wired) Apple earbuds has changed.  When I give it a single tap, the music will pause or play, which is normal.  However, I'm also used to double-tapping to advance to the next song, like on my iPhone.  That feature is gone.  Also, on the first tap, the "Enable Siri?" dialog comes up: I decided to disable Siri as I don't use it much and the additional battery drain (that I may be making up) doesn't seem worthwhile to me.  How can I disable this dialog and revert my iTunes behaviour back to what I'm used to?


'bpy_prop_collection' object has no attribute 'link'?

I'm using Blender 2.8+ and I found a web page containing a nice . I copied the script in Blenders text editor and an error occurred at line 88:  bpy.context.scene.objects.link (object)      AttributeError: 'bpy_prop_collection' object has no attribute 'link'   Error: Python script failed, check the message in the system console   Unfortunately, I have no idea what a 'bpy_prop_collection' is and I don't know where to start fixing this issue. What I need to do in order to make the script work for Blender 2.8x?


I'm looking for Python code that removes C and C++ comments from a string. (Assume the string contains an entire C source file.)  I realize that I could .match() substrings with a Regex, but that doesn't solve nesting /*, or having a // inside a /* */.  Ideally, I would prefer a non-naive implementation that properly handles awkward cases.


Is it possible to implement C++ as a C library with macros?

Would it be theoretically possible to implement C++ keywords, classes syntax etc. using a C library with right macros? (i.e. prepare a library which would make any C++ code compile using C compiler). I guess the answer is probably "no", but I wonder if you can prove it.


Lower and upper bounds for the $n$th prime number

Is there anything one could say about in what region a prime number is guaranteed to be in? A general equation for $a$ and $b$, dependent on $n$, in $a<p_n<b$?


I've been stuck on the following puzzle:  There are $2$ one-letter words in English ("I" and "a"), and there are $124$ two-letter words. Let $a_n$ be the number of strings of $n$ letter that may be formed from some sequence of one- and two-letter words, by concatenating them all together. Prove, by induction on $n$, that $a_n \le 13^n \ \forall n$.  I would appreciate it if people could please take the time to explain this.


Error when using youtube-dl to downloading videos from a YouTube channel output: /usr/bin/env: ‘python’: No such file or directory

I am trying to download all videos from a YouTube channel to then convert the videos to a WAV file  Entering the following command:  ~$ youtube-dl https://www.youtube.com/channel/UCa1Cl-msOfWu5aBzbYCJVVA --audio-format wav   Returns:   /usr/bin/env: ‘python’: No such file or directory   I had entered a command that someone suggested to solve an issue where the output is was something like 'no video format avaliable'. But instead it had return that output instead of downloading the videos and converting videos to WAV format.  The command I used to download youtube-dl was sudo apt-get install.  Entering   :~$ apt-cache policy youtube-dl   Returns:   youtube-dl:  Installed: (none)   Candidate: 2020.03.24-1   Version table:      2020.03.24-1 500         500 http://au.archive.ubuntu.com/ubuntu focal/universe amd64 Packages         500 http://au.archive.ubuntu.com/ubuntu focal/universe i386 Packages   EDIT  $ youtube-dl returns: /usr/bin/env: ‘python’: No such file or directory


What books would you recommend to start learning about software testing

I'm trying to learn more about software testing, so I want to know which books you would recommend on this topic


y∈ℝ, y>−1 and y≠0. Show that for k∈ℕ, k>1: (1+y)^k > 1+ky

Let $y∈ℝ$, $y>−1$ and $y≠0$. Show that for $k∈ℕ$, $k>1$ we have $(1+y)^k > 1+ky$.       I've been trying to solve this for the last two hours and still don't really have any idea on how to do it.


In R how to you modify a logistic regression where the cost of selecting one of the classes is much higher than the other.

Say I have the following in R  rm(list=ls()) set.seed(1000) n<-20 x<-rnorm(n, 0.5,1) y<-rnorm(n, 0.5,1) type<-rep(2,n) df1<-data.frame(x,y,type) x<-rnorm(n, -0.5,1) y<-rnorm(n, -0.5,1) type<-rep(5,n) df0<-data.frame(x,y,type) df<-merge(x=df0,y=df1,all=T) plot(df$x,df$y,col=df$type)     Now as you can see I have classes that overlap -- say the cost of classifying the red class incorrectly is 10 times the cost of classifying  the blue class incorrectly.  Say I want to use a logistic regression -- how would I do incorporate the cost into my logistic regression model?


Turning vector grid into individual shapefiles using QGIS?

I am using QGIS and I created a vector grid on a crop field in order to cut it into plots. I want to save each grid cell into individual polygon shapefiles automatically.  Here is an example of a vector grid I would like to split into 117 shapefiles:    Eventually, I did it manually with the selection tool and "Save as" but it is really time-consuming when there are more than 100 plots to save.    Is there any way to do it faster and more automatically?  Each plot as an attribute named "Plot" that can discriminate against them (basically being id + 1). It's the attribute used here to label them.


Why does frequency remain unchanged in light refraction but wavelength doesn't?

Since the frequency of an electromagnetic wave does not change during refraction but the velocity changes, the wavelength must therefore change. But why doesn't the frequency change in the first place? I heard answers like that frequency is the property of the source but wavelength is not. Even of this is the right answer explanations are not adequate.


Can someone help me decipher the specs of a camera lens.   Purely for example, I see a lens being advertised as:  AF Nikkor 24-50mm   1:3.3-4.5 Wide Angle Zoom  What is AF?  What exactly does 24-50mm refer to?  What is 1:3.3-4.5 telling me?  In general, are there quick observations you can make from seeing specs like these, for example, saying "ah yes, 24-50mm is good for indoor weddings" etc.?


Does $n-4\nmid2n$ for all $n\in\mathbb{N}, n>12$?

From the table of values of $\frac{2n}{n-4}$ it seems to me that the expression never evaluates to an integer for all natural numbers $n$ greater than $12$. How should I go about proving it?


I have recently started using generic methods in my projects. I am working on a chess project where every piece class extends to Pieces.java.    And in the Player.java, I have added this code:  public class Player {     Pieces[] pieces = new Pieces[16];     Player() {         …         init();     }     private void init() {         //initialize pieces array with all pieces.         pieces[0] = new Pawn(new Point(6, 0), this);         pieces[1] = new Pawn(new Point(6, 1), this);         pieces[2] = new Pawn(new Point(6, 2), this);         pieces[3] = new Pawn(new Point(6, 3), this);         pieces[4] = new Pawn(new Point(6, 4), this);         pieces[5] = new Pawn(new Point(6, 5), this);         pieces[6] = new Pawn(new Point(6, 6), this);         pieces[7] = new Pawn(new Point(6, 7), this);         pieces[8] = new Rook(new Point(7, 0), this);         pieces[9] = new Knight(new Point(7, 1), this);         pieces[10] = new Bishop(new Point(7, 2), this);         pieces[11] = new Queen(new Point(7, 3), this);         pieces[12] = new King(new Point(7, 4), this);         pieces[13] = new Bishop(new Point(7, 5), this);         pieces[14] = new Knight(new Point(7, 6), this);         pieces[15] = new Rook(new Point(7, 7), this);     }     public <T extends Pieces> T getPiece(Point point) {         for(Pieces piece: pieces) {             if(piece.isAlive() && piece.getCurrentPoint().equals(point))                 return (T)piece;         }         return null;    } }   But now, IntelliJ gives me a warning, "Unchecked cast from "Pieces" to T. Even when I mentioned that  and all the elements of pieces array is a subclass of Pieces, even then IntelliJ gives me a warning: "Unchecked cast from Pieces to T". How am I supposed to fix this.  Please do not mark this as duplicate because the answer of other questions have not helped me.


How to replace values in Python nested lists without saving only the last value of the iteration


How do I install Windows 10 alongside existing Ubuntu 20.10 while retaining data on existing Ubuntu

I need to install Windows 10 for some work but I already have Ubuntu 20.10 installed on my HDD. All the space on the HDD has been allocated so no free space. I read that it's better to install Windows first then Ubuntu. So my plan is to back up my entire Ubuntu OS to an external drive using Timeshift, then to install Windows and reinstall Ubuntu and once this is done restore the Ubuntu system using Timeshift. Will this work? My concern is that GRUB will be affected and also fstab with existing partitions assigned, as I think these will change after Windows/Ubuntu installation. Is there a better way to do this while retaining my entire Ubuntu OS? Output of lsblk:


Write text over stretched tilde in math mode

How can write text over stretched tilde in math mode? I want the tilde length to be automatically stretched to the size of the text on it. Like this figure!  MWE: \documentclass{article} \usepackage{amsmath, amssymb} \begin{document} \[ \sin x\stackrel{x\to 0}{\sim} x \] \end{document}


how to remove 'Chapter' word only from headings?

I want to suppress the word 'chapter' from my headings but to leaving the normal 'CHAPTER X: Name of the chapter' in the document.  I want that my headings says '# Name of the chapter', not 'Chapter # Name of the chapter'.


I want to create a   How can I create a formfield with N fields, each 5 mm wide with separations like in the picture?    At the moment I use a workaround with a for loop, but this renders the code hard to maintain. Finally I need a function \formline{N}{cellwidth}{label}{value} to create the complete formfield and fill it with an optional value:   The following code is available on .   \documentclass[a4paper,11pt]{article} \usepackage[utf8]{inputenc} \usepackage{tikz} \usetikzlibrary{shapes}  \thispagestyle{empty} % no pagenumber. The form should be a stand alone macro... later.  \definecolor{SEPAOrange}{RGB}{254,213,161} \definecolor{SEPADOrange}{RGB}{253,185,19} \definecolor{SEPABlindcolor}{RGB}{255,0,0} \begin{document} \begin{tikzpicture}[x=1 mm, y=-1mm] \pgfmathsetmacro{\yh}{4.2333} % y heigth step defined as 1/6 inch => 1/6 * 25.4 mm = 4.2333 mm \pgfmathsetmacro{\xs}{9} % x start (own definition) \pgfmathsetmacro{\xe}{141.5} % x end (own definition) \pgfmathsetmacro{\widefield}{4.9859} % def: 134.62 mm / 27 \pgfmathsetmacro{\narrowfiels}{3.9594} % def: 134.62 mm/ 34  \filldraw[draw=black,color=SEPAOrange] (7.62, 4.5*\yh) rectangle (149.86-7.62,105.83-1); %orange background  \filldraw[draw=black,color=white] (\xs, 5*\yh) rectangle (\xe, 6.5*\yh -1.5); %Recepient 27 Char \foreach \x in {1,...,26} {  \draw[color=SEPAOrange, line width=0.3mm] (7.62 + \x*\widefield, 5*\yh ) -- (7.62 + \x*\widefield, 6.5*\yh);  \draw[color=SEPAOrange, line width=0.7mm] (7.62 + \x*\widefield, 5.8*\yh ) -- (7.62 + \x*\widefield, 6.5*\yh); }  \filldraw[draw=black,color=white] (\xs, 7*\yh) rectangle (\xe, 8.5*\yh -1.5); %IBAN 34 Char \foreach \x in {1,...,33}  \draw[color=SEPAOrange, line width=0.3mm] (7.62 + \x*4, 7*\yh ) -- (7.62 + \x*4, 8.5*\yh);  \filldraw[draw=black,color=white] (\xs, 9*\yh) rectangle (\xe, 10.5*\yh -1.5); %BIC \filldraw[draw=black,color=white] (\xe-12*5, 11*\yh) rectangle (\xe, 12.5*\yh -1.5); %Value 12 Char  \filldraw[draw=black,color=white] (\xs, 13*\yh) rectangle (\xe, 14.5*\yh -1.5); %Subject1 \filldraw[draw=black,color=white] (\xs, 15*\yh) rectangle (\xe, 16.5*\yh -1.5); %Subject2 \filldraw[draw=black,color=white] (\xs, 17*\yh) rectangle (\xe, 18.5*\yh -1.5); %Subject3  \filldraw[draw=black,color=white] (\xs, 19*\yh) rectangle (\xs+22*5, 20.5*\yh -1.5); % IBAN 22 Char  \filldraw[draw=black,color=white] (149.86-17.59, 19* \yh) rectangle (\xe, 20.5*\yh -1.5); % counter \filldraw[draw=black,color=white] (\xs, 21* \yh) rectangle (42.52, 24.5*\yh); % date \filldraw[draw=black,color=white] (42.52+5, 21*\yh) rectangle (149.86-17.59, 24.5*\yh); % signature  \draw[color=SEPADOrange] (0, 4.5 *\yh) --(149.86, 4.5*\yh); upper dark orange line \draw[color=SEPADOrange] (0, 20.5 *\yh) --(149.86, 20.5*\yh); lower dark orange line \draw[draw=black,color=black, line width=0.3mm] (0,0) rectangle (149.86,105.83); % black border %\draw[align=left] at (\yh,\yh) {SEPA-Überweisung};  \end{tikzpicture} \end{document}


Let $T:V\to V$ be a linear map, where $V$ is an inner product space. Given $T^2=\frac{T+T^*}{2}$, prove that $T$ is normal and that $T=T^2$.

Let $T:V\to V$ be a linear map, where $V$ is a finite-dimensional inner product space. Given $T^2=\frac{T+T^{*}}{2}$, I would like to prove that $T$ is normal and that $T=T^2$. The first part, to prove that $T$ is normal, is quite easy: from $T^2=\frac{T+T^{*}}{2}$ we'll have $\,T^{*}=2T^2 - T$, and as $TT^{*} = 2T^3 -T^2 = T^{*}T$. Now, I need to prove that $T=T^*$, then $T = T^2$ is immediate. I have been thinking about this question for some days and I can't figure out in what technique to prove that $T = T^{*}$.


Can I import my Local Park into Facebook?

Imagine my surprise when I find out that Dragonvale is on Android now, in addition to iOS. So, to see what all the craze is about, I decide to get into it. I don't really have a Facebook, so I just bypassed all that. However, this locks me out of all the social stuff, including free Gems. This is, obviously, Not Ideal, so I made a Facebook account basically just for Dragonvale. Seems simple enough.  Too bad that, apparently, my Local Park isn't my Facebook Park! Is there a way to force my Local Park to be my Facebook Park? Or am I screwed unless I want to start over, which I'd really rather not do?


Automorphism group of a lie algebra as a lie subgroup of $GL(\frak g)$

Let $G$ be a lie group with lie algebra $\frak{g}$. Let $Aut(\frak g)$ be the automorphism group of $\frak{g}$.   Its clear to me that $Aut(\frak{g})$ $\subset GL(\frak{g})$ since any automorphism of $\frak{g}$ is also a linear transformation. Now i have several questions:   How do i prove that $Aut(\frak{g})$ is actually a lie subgroup of $GL(\frak{g})$? I've tried playing with actions to realize $Aut(\frak g)$ as an orbit or an isotropy subgroup but nothing worked out... Say $H \subset G$ is an abstract subgroup (not necessarily lie). Are the following statements equivalent?   $$\{T_e H \text{  is closed under the lie bracket of } \frak{g} \}$$  $$ \{H \text{is a lie subgroup of } G\}$$   How does the lie algebra of $Aut(\frak g)$ look like? When does $Aut(\frak g)$ $= G$? what does $Aut(\frak g)$ tell me about $G$?


when i run sudo apt-get update i got this error

E: The repository 'http://ppa.launchpad.net/webupd8team/java/ubuntu focal Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.  please help me to solve this issue


If the space-time metric is expanding with the expansion of the universe, if I could travel back in time, would I be less dense than the matter in that previous era?


i cannot install any software through software center and when i try to remove software center this appear  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?


Disabling the "Enable notifications?" popup in Firefox

If I'm on a page that has web notifications (like Slack or others), Firefox asks me if I want to enable them. However, my choices are "Yes" or "Ignore for now". The problem is, if I select "Ignore", every time there is a notification it asks me again. This is incredibly annoying.   How do I disable this completely? (I would accept disabling this feature entirely if that's easiest.)


Extra "s" in acro with plural in first use

I really hope I am posting in the right forum and location. My apologies if it is incorrect.  Essentially, I have a strange problem that occurs when the first use of an acronym happens to be in plural form. In that case, an 's' is appended in front of the short form as well as in the end. This happens not only for this particular one, but also several other acronyms I use, and I have not managed to work around it by using 'short-plural', 'short-plural-form', 'long-plural', or 'long-plural-form'.   Any help is appreciated. See below for an MWE and the result I get from that exact code.  \documentclass[a4paper,11pt]{report} \usepackage{acro} \DeclareAcronym{bc}{short =BC, long = boundary condition} \begin{document} Then, \acp{bc} are applied. \end{document}     Thank you very much!


While using the command   sudo apt-get upgrade   I lost my internet. When I again used the command   sudo apt-get upgrade   I got the following error:  Unable to fetch some archives, maybe run apt-get update or try with --fix-missing   What to do? I am using 14.04 version.


So I want to start a small Minecraft server to raise money toward a bigger one, so I download a Spigot server (and I have owned some servers in the past so I knew how to set it up). When I finish setting up port forwarding and all that crap, then when I start it up it says this:  **** FAILED TO BIND PORT!   So I went online to find how to fix it and I was met with a number of different methods. I tried changing the port, changing the IP, using the cmd, using task manager, closing Java, and then started it back up. I was met with the same message. I tried to fix again, but it still gave me the error.


Pauli exclusion principle states that 2 identical electrons cannot be in the same state, where state includes a spacial component.   I have heard that, in order to avoid being in the same state, in a white dwarf, the De Broglie wave length of the electrons becomes shorter and shorter, meaning that they have a higher and higher momentum/ energy. Eventually, when the gravitational pressure is too high, they form neutron stars, since neutrons have smaller De Broglie Wave lengths due to their higher mass.  My question is, by applying more and more pressure, can we confine more and more identical neutrons/ other fermions in an arbitrarily small space, eventually forming a black hole? Or, at some point, fermions must be converted into bosons?


What's the main difference between the non-uniform probabilistic polynomial-time adversary and the probabilistic polynomial-time adversary?

When I am reading some secure computing papers, the authors always assumed that there exist some adversaries, such as non-uniform adversary and the probabilistic polynomial-time adversary. So my question is that what are the main difference between the non-uniform probabilistic polynomial-time adversary and the probabilistic polynomial-time adversary ?


Do I need a balanced sample (50% yes, 50% no) to run logistic regression?

I'm working on a project using logistic regression to predict student retention. The data were collected through three self-report instruments. We are trying to find out which predictors are powerful enough to predict the at-risk students. I came across some articles saying a balanced sample (50% stay, 50% dropouts) is desirable for such study, e.g. Glynn, J.G., Sauer, P.L., & Miller, T.E. (2003). , NASPA Journal, 41 (1), 41-67:     A problem however, is that the distribution of the dependent variable is likely to be highly skewed toward persistence. For example, if 85% of the analysis sample were persistors, a classification model that classified every student as a persistor would have a success rate of 85%, or would classify 85% of student correctly. To resolve this issue, the maintenance of relative balance between the number of dropouts and the number of persistors (about 50% each) in the analysis sample was desirable.   Is this true? Our sample only has about 25%-30% dropout students. Will this affect the results?


"Undefined reference to" template class constructor

I have no idea why this is happenning, since I think I have everything properly declared and defined.  I have the following program, designed with templates. It's a simple implementation of a queue, with the member functions "add", "substract" and "print".  I have defined the node for the queue in the fine "nodo_colaypila.h":  #ifndef NODO_COLAYPILA_H #define NODO_COLAYPILA_H  #include <iostream>  template <class T> class cola;  template <class T> class nodo_colaypila {         T elem;         nodo_colaypila<T>* sig;         friend class cola<T>;     public:         nodo_colaypila(T, nodo_colaypila<T>*);  };   Then the implementation in "nodo_colaypila.cpp"  #include "nodo_colaypila.h" #include <iostream>  template <class T> nodo_colaypila<T>::nodo_colaypila(T a, nodo_colaypila<T>* siguiente = NULL) {     elem = a;     sig = siguiente;//ctor }   Afterwards, the definition and declaration of the queue template class and its functions:  "cola.h":  #ifndef COLA_H #define COLA_H  #include "nodo_colaypila.h"  template <class T> class cola {         nodo_colaypila<T>* ult, pri;     public:         cola<T>();         void anade(T&);         T saca();         void print() const;         virtual ~cola();  };   #endif // COLA_H   "cola.cpp":  #include "cola.h" #include "nodo_colaypila.h"  #include <iostream>  using namespace std;  template <class T> cola<T>::cola() {     pri = NULL;     ult = NULL;//ctor }  template <class T> void cola<T>::anade(T& valor) {     nodo_colaypila <T> * nuevo;      if (ult)     {         nuevo = new nodo_colaypila<T> (valor);         ult->sig = nuevo;         ult = nuevo;     }     if (!pri)     {         pri = nuevo;     } }  template <class T> T cola<T>::saca() {     nodo_colaypila <T> * aux;     T valor;      aux = pri;     if (!aux)     {         return 0;     }     pri = aux->sig;     valor = aux->elem;     delete aux;     if(!pri)     {         ult = NULL;     }     return valor; }  template <class T> cola<T>::~cola() {     while(pri)     {         saca();     }//dtor }  template <class T> void cola<T>::print() const {     nodo_colaypila <T> * aux;     aux = pri;     while(aux)     {         cout << aux->elem << endl;         aux = aux->sig;     } }   Then, I have a program to test these functions as follows:  "main.cpp"  #include <iostream> #include "cola.h" #include "nodo_colaypila.h"  using namespace std;  int main() {     float a, b, c;     string d, e, f;     cola<float> flo;     cola<string> str;      a = 3.14;     b = 2.71;     c = 6.02;     flo.anade(a);     flo.anade(b);     flo.anade(c);     flo.print();     cout << endl;      d = "John";     e = "Mark";     f = "Matthew";     str.anade(d);     str.anade(e);     str.anade(f);     cout << endl;      c = flo.saca();     cout << "First In First Out Float: " << c << endl;     cout << endl;      f = str.saca();     cout << "First In First Out String: " << f << endl;     cout << endl;      flo.print();     cout << endl;     str.print();      cout << "Hello world!" << endl;     return 0; }   But when I build, the compiler throws errors in every instance of the template class:   undefined reference to `cola(float)::cola()'... (it's actually cola'<'float'>'::cola(), but this doesn't let me use it like that.)  And so on. Altogether, 17 warnings, counting the ones for the member functions being called in the program.  Why is this? Those functions and constructors WERE defined. I thought that the compiler could replace the "T" in the template with "float", "string" or whatever; that was the advantage of using templates.  I read somewhere here that I should put the declaration of each function in the header file for some reason. Is that right? And if so, why?  Thanks in advance.


What determines the quality of loot in horadric caches?

Ofcourse your character's level and the random factor affect what you get in the caches, but is there anything else that has influence on the loot from a cache? For example, does it matter on what difficulty I complete the bounties? Does it matter on which difficulty I open them? Anything else?    For clarification, I'm talking about the reward you get from completing all bounties in one act in adventure mode. A new feature in the Reaper of Souls expansion. Upon completing all bounties in one act you get a one time use cache which drops some loot when used. It usually drops a few crafting materials, some rift keystone fragments and a couple of blues and yellow. I've had one legendary so far out of 4 or 5 caches.    I understand there isn't nearly enough data from the community yet to answer this question based on results. But if someone had a link to a blue post explaining this or perhaps an ingame reference that answers this, that would be awesome. Damn it, I might just spend the next few evenings farming normal - T1 caches and see if I get significant differences in drops :D.


What is the difference between a law and a theory?  Some seem to think that a law is a single relationship or a single equation, while a theory is an explanatory framework in which these laws come into play.  But do physicists keep this distinction intact? They say "Newton's laws of motion", right? But isn't Newton's laws an "explanatory framework"? All interaction is "explained" as forces (vectors) between matter, right?


If $x_1,x_2,\ldots,x_n$ are the roots for $1+x+x^2+\ldots+x^n=0$, find the value of $\frac{1}{x_1-1}+\frac{1}{x_2-1}+\ldots+\frac{1}{x_n-1}$

Let $x_1,x_2,\ldots,x_n$ be the roots for $1+x+x^2+\ldots+x^n=0$. Find the value of   $$P(1)=\frac{1}{x_1-1}+\frac{1}{x_2-1}+\ldots+\frac{1}{x_n-1}$$   Source: IME entrance exam (Military Institute of Engineering, Brazil), date not provided (possibly from the 1950s)  My attempt: Developing expression $P(1)$, replacing the 1 by $x$, follows $$P(x)=\frac{(x_2-x)\cdots (x_n-x)+\ldots+(x_1-x)\cdots (x_{n-1}-x)}{(x_1-x)(x_2-x)\cdots (x_n-x)}$$    As $x_1,x_2,\ldots,x_n$ are the roots, it must be true that   $$Q(x)=(x-x_1)\cdots(x-x_n)=1+x+x^2+\ldots+x^n$$ and  $$Q(1)=(1-x_1)\cdots(1-x_n)=n+1$$ Therefore the denominator of $P(1)$ is  $$(-1)^{n} (n+1).$$ But I could not find a way to simplify the numerator.  Another fact that is probably useful is that  $$1+x^{n+1}=(1-x)(x^n+x^{n-1}+\ldots+x+1)$$ with roots that are 1 in addition of the given roots $x_1,x_2,\ldots,x_n$ for the original equation, that is  $$x_k=\text{cis}(\frac{2k\pi}{n+1}),\ \ k=1,\ldots,n.$$  This is as far as I could go...    Hints and full answers are welcomed.


Idiom or expression that would imply "someone is a habitual liar"

I'm looking for an idiom or expression for describing people who tell lies out of habit (so you cannot trust them at all).   I know that these people are called , but I'm not looking for psychological terms.  Is there any idiom or expression for describing such people?   For example:     "Did X tell that to you?! Come on, don't believe him/her. Don't you know he/she ___ (=is a habitual liar)?"


Extremely Simple Bibliography Not Working

I've created a simple LaTeX file.  \documentclass{article} \begin{document}  \bibliographystyle{plain} \bibliography{bibliography.bib}  \end{document}   My bibliography.bib file is in my main working directory and looks like this  @book{1,     author = {Bill Bezio},     title = {Numerical Simulations},     date = {August 2016}, }   When I build and view the pdf in TexStudio (OS is Ubuntu 16.04) I get one page with the word "References" at the top and nothing else. There is a footer of "1" at the bottom but no references. Where are the references?


Is it possible to remove subject relative pronouns? How?

Consider the following sentences.  Al Pacino is a famous actor [who] played Michel Corleone in The Godfather movie. Samsung is a very big company [which] produces home appliances.  Question: is it possible to remove subject relative pronouns (who/which)? If so, how?


Allow moderators or gold tag badge holders to prevent questions from being on the hot network questions (HNQ) list

Sometimes a question that is not representative of a site makes the HNQ list. This can lead to a large bump in traffic on a question the community may not be well equipped to handle. I propose that moderators and gold badge holders in the tag be able to set the "hotness points" to zero (or vote to reduce the points).  The idea is for the HNQ to represent questions that are both "popular" and a good (not just not bad) fit for the site.


How can I extrude edges inwards so the offset distance is same for all edges?

How can I extrude edges inwards and keep same distance for all exuded edges?  When I try to extrude (see pic 1) and press "s" all extruded edges have different offset from original (see pic 2) and I need extruded edges to have same offset distance from original. How can I do so?


Dial PPPoE connection on Windows startup

Is there a way to automatically dial a PPPoE connection on startup? In Mac OS X, this is done automatically after login. It was also possible in Windows XP: when creating a new connection, it also created a shortcut to it on the desktop. Adding it to the startup folder and setting it to not prompt for credentials solved the problem.  But in Vista and Windows 7, there are no shortcuts to the newly created connections, so I can't do the same thing here. Is there any other way to do this?


Where do I get HM "Rock Smash" to get through Rusturf Tunnel in Pokemon Omega Ruby/Alpha Sapphire (GEN VI)?

I have reached the part where I have to go through the Rusturf Tunnel and there are boulders that are breakable. The NPC that said he was digging the tunnel by himself said the rocks are too hard and he can't get through and when I walked closer to them, the player mentioned "if only I could smash these rocks".  Where can I acquire Rock Smash?


Prove (or derive) the de Polignac formula for the prime decomposition of $n!$

I can't seem to find any papers published dedicated to show that the de Polignac formula has a rigorous derivation. From  for the formula:     Let $n \geq 1$ be an integer. The prime decomposition of $n!$ is given by   $$n! = \prod_{\text{prime } p \leq n}\;p^{s_p(n)}$$   where   $$s_p(n) = \sum_{j=1}^\infty \left\lfloor \frac{n}{p^j} \right\rfloor $$   Could someone please let me know the derivation or provide a link to a paper which sheds light upon the derivation of the aforementioned formula?   Thank you in advance.


Is there a way to get wireshark to capture packets sent from/to localhost on Windows?

Is there a way to get wireshark to capture packets sent from/to localhost?    When I monitor traffic going from my computer to another, or from another computer to my computer, then it works.  But from localhost to localhost does not register anything.


Using AMPScript to parse an XML feed. Client is switching to JSON. Is there something similar to  for JSON in AMPScript? I am confined to using the members login area and not an external API application.


I can't make ad-hoc from my netbook (Ubuntu 12.04). It has internet source from ethernet. I have tried making from network manager. But it always says 'Wireless Network Disconnected' and can't be detected by neither my other laptop nor my cell phone which have wifi. How can I make adhoc from it?   I have already tried making a connection in Network Manager a lot of times, but it still can't connect and appear notification 'Wireless Network Disconnected'.


5, 8, or 12MP setting best overall for Panasonic Lumix DMC-ZS15, JPEG, 5x7 prints

My Panasonic Lumix DMC-ZS15 P&S (about 2yrs. old, records in JPEG) takes fine pictures for my purposes (at most 5x7 prints). It has 12.1MP, 16x zoom, and a 1/2.3 MOS sensor. I always use the "high quality" setting and auto settings for aperture and shutter. I have always wondered which MP setting would give me the best resolution vs. noise in the final image. I asked a similar question 2days ago, but now I am looking for a more specific answer. I realize this new question may be more specific, elementary,and possibly neurotic than you guys care to deal with, so please feel free to ignore me if that is the case. I have experimented and learned that I probably do not need all 12MP but still cannot make up my mind between 5 & 8MP. Thank you for your consideration.


Definition of power set uses strict subset

In the following  one finds the following:  Examples. The following are all examples of σ-algebras. (HW: check this in each case) • Let P(X) denote the collection of all subsets of X, i.e. P(X) := {A : A ⊂ X} (we write ⊂ rather than ⊆, so in our notation X ⊂ X is a true statement). P(X) is called the power set of X, and is a σ-algebra.  I don't understand how using the strict subset makes X ⊂ X a true statement, or what the author is trying to get across here?


How do physicists justify using $c^2$ in equations?

Excuse my ignorance but I see physicists use $c^2$ in equations and I was wondering what reasoning they use to justify $c^2$ since, as far as I understand, $c^2$ must be an absurd quantity because there is a speed limit imposed by physicists themselves at $c$. If there is no motion faster than $c$, how do you justify using $c^2$ in an equation?


How to De-seasonalize a time series based on trading days?

I have a time series of monthly data points with a corresponding cost. Within these months, if you strip out the trend, I believe the cost to be highly correlated to the number of trading (or business days). What I don't understand is how exactly to strip this out? If the month's trading days can vary (example - January has 21 days one year and 22 another), I don't think I can rely on a typical method of averaging the historical monthly seasonalities. Is there a better way to go about doing this?


Edited the pdf in PDFelement & when you try to view a document in Adobe Reader or Acrobat, you receive the error, "There was a problem reading this document (131)." Why is this happening?


Do you have to take the Attack action before you can make the bonus-action attack from the Crossbow Expert feat?

The third benefit of the  feat says (PHB, p. 165):  When you use the Attack action and attack with a one-handed weapon, you can use a bonus action to attack with a hand crossbow you are holding.  I am aware that in general, .  However, does the wording of Crossbow Expert's third benefit mean that it requires taking the Attack action before the bonus action?  Compare/contrast that wording with that of:  the third benefit of the monk's  feature:  When you use the Attack action with an unarmed strike or a monk weapon on your turn, you can make one unarmed strike as a bonus action. For example, if you take the Attack action and attack with a quarterstaff, you can also make an unarmed strike as a bonus action, assuming you haven't already taken a bonus action this turn.   the monk's Flurry of Blows option for the  feature:  Immediately after you take the Attack action on your turn, you can spend 1 ki point to make two unarmed strikes as a bonus action.   and the  feat (PHB, p. 170):  If you take the Attack action on your turn, you can use a bonus action to try to shove a creature within 5 feet of you with your shield.  Relevant Q&A:


Let $\mathbf X = \Bbb R$ with distance function defined by $d(x,y) = {|x-y|}^\alpha$ , where $\alpha \in \Bbb R$  $(0<\alpha\le1)$.  Prove that $(\Bbb R , d)$ is a metric space.  The first three properties are easy, so I only need the triangle inequality. I tried to use Bernoulli's inequality, but did not lead me to the proof.  $d(x,y) \le d(x,z) + d(z,y)$  Please help me, Spanish is my language.


How did the universe get so big so fast?

The universe started at the big bang around 15 billion years ago. The universe is now at least 92 billion light-years in diameter.   Together, don't these mean that the universe, at some time in the past or present, was expanding at a rate of faster than 1 ly/y in every direction? Why is that possible?


When and why will a compiler initialise memory to 0xCD, 0xDD, etc. on malloc/free/new/delete?

I know that the compiler will sometimes initialize memory with certain patterns such as 0xCD and 0xDD.  What I want to know is when and why this happens.  When  Is this specific to the compiler used?  Do malloc/new and free/delete work in the same way with regard to this?  Is it platform specific?  Will it occur on other operating systems, such as Linux or VxWorks?  Why  My understanding is this only occurs in Win32 debug configuration, and it is used to detect memory overruns and to help the compiler catch exceptions.  Can you give any practical examples as to how this initialization is useful?  I remember reading something (maybe in Code Complete 2) saying that it is good to initialize memory to a known pattern when allocating it, and certain patterns will trigger interrupts in Win32 which will result in exceptions showing in the debugger.  How portable is this?


Is there a GNU/Linux equivalent to the Mac OS X open command?

In Mac OS X there is a handy open command that opens the target file or directory in the default GUI application meant for it:  open /usr/local/share   will bring up a Finder window with the /usr/local/share directory open in it (BTW I don't know of any other way to open this particular directory in Finder) and  open ~/Desktop/example.jpg   will bring up a Preview window displaying the example.jpg file located on the current user's desktop.  Is there an equivalent in the GNU/Linux world?


Latex error- file 'fancyvrb.sty' not found

I am using Miktex2.9 and Texniccenter and error is coming 'fancyvrb.sty' not found, so what to do can i download it , if yes after downloading where to put the file so that after running the texniccenter it finds the file. Please help


Are newer questions always considered the duplicate between the two?

I thought this was interesting, a question  2 years ago was just marked as a duplicate. When I followed  the question was infact very simillar to mine, except it had only been asked yesterday. I'm glad to see it got answers, as mine didn't recieve much attention. Can anyone explain why @ Rishat Muhametshin question got 24 upvotes and several answers and mine didn't get any?  Is there a policy as to which question is considered the duplicate? I did ask mine first.


Converting MySQL AES_DECRYPT() to Postgres decrypt()

I have this MySQL query using  that is the following:  SELECT *  FROM data_tbl WHERE AES_DECRYPT(data_point,'aBcDeF')='data_1';   I've figured out as much that the equivalent in Postgres 11 is  (F.25.4. Raw Encryption Functions) and the query would look something like this:  SELECT *  FROM data_tbl AND decrypt(data_point,'aBcDeF','aes')='data_1';   At least, the documentation for both leads me to believe that these are equivalent.  The data was dumped from MySQL and imported into PostgreSQL.   The data-point field in MySQL is type varbinary(255) and the values all show BLOB in MySQL Workbench.  The data_point field in Postgres is type bytea and the values all show [binary data] in pgAdmin.    Whether those data types are equivalent, I admit, I'm not sure.  The MySQL query works and finds a record based on he criteria. The PostgreSQL does not, although the record is in there. So it seems like one of three things:   The data types (varbinary(255) vs bytea) are not equivalent The data does not match (BLOB vs [binary data]) are not equivalent The functions (AES_DECRYPT vs decrypt()) are not equivalent   I did try to decrypt the value in PostgreSQL just to see what it is in a readable format by first trying:  SELECT decrypt(data_point, 'aBcDeF', 'aes')  FROM data_tbl;   But that just returned [binary data] for all the rows.  Then I came across  to use convert_from as in:  SELECT convert_from(decrypt(data_point, 'aBcDeF', 'aes'), 'SQL_ASCII') FROM data_tbl;   However, I just get this error:  ERROR:  invalid byte sequence for encoding "UTF8": 0xcf 0xf5 SQL state: 22021   So at this point I'm stumped as to how to resolve the primary issue. The primary issue being doing the equivalent of AES_DECRYPT but in PostgreSQL 11. The last error message isn't so much an issue, but it is likely related to decrypt() not returning the same results.  Any suggestions?


I installed Lubuntu desktop using terminal but my laptop reboots still as Ubuntu

I installed Lubuntu desktop, but after reboot I still see the default Ubuntu desktop. However, when I shut it down, the Lubuntu logo appears. When I turn it on, it's back to Ubuntu again.  What could be the problem, and how can I fix it?


Can Green Lanterns make copies of their Power ring?

Suppose that a Green Lantern agent wants to assign a friend of his as his/her deputy for certain reason: for example, ensuring the safety of his home world while he/she is fighting crime several light years away. Could he/she use his/her willpower to create a copy of his/her ring?   Granted, the process might require a huge amount of power (from the ring and from its user), perhaps too much for it to be practical (conservation of energy), but could you make, at the very least, an imperfect copy in theory?  Just to get extraneous issues out of the way, let's assume this friend of agent is strong-willed enough to be a ring-bearer (perhaps even a prospective Lantern!), and the Guardians have sanctioned this experiment for the time being (out of sympathy or at least scientific curiosity).  Furthermore, I believe Jordan's Green power ring has been 'copied' in at least one comic story-line (Superman: Red Son), though I haven't really read it and don't quite know how that universe's Jordan accomplished it.


Why do the two hemispheres of the brain control the opposite sides of the body?

Why does the left hemisphere control the right and the right hemisphere control the left? I googled it but didn't find a good answer regarding this. Could someone explain?  Does this adaptation help in the speed of transmission of nerve impulses?


In special relativity, how can time dilation happen from both point of view?

Say I have the following setup.  Person A is stationary.  Person B is to the very far right of person A and is travelling towards person A in a plane at very high speed but sufficiently far away so that the collision time is some big number.  Also say both people are waving at each other frantically (say once per second in local frame time).  From person A's frame, person B's clock became very slow.  So, to take as an example, by the time (in A frame) that B passes A, only one tick of person B's clock has gone by.  That means we can only see person B waving once.  But from B's POV, the reverse is true, it is person A's clock that has only ticked once.  From B's frame, he has waved many many more times.  So what happened to those extra waves that person A cannot see?  Is it because in B's frame, although he waves many many times, only one tick of person A has occured, so person A can only see "one tick worth" of waving?


I have recently received some reputation which made me eligible for the association reputation where you get 100 reputation for every site you have account on stackexchange.  I was just looking at the top userslist  and when I scrolled to the top, I saw my username. This is for all time. Also, this does not valid as it shows me in top 2% this month.  How is it possible that I am at this top of the list? Is it because it is designed to show the user currently logged-in at the top?


I'm familiar with several process signals and what they do, but I would like to understand them all.  There are three things I would like to find out about each signal.   What the signal does  When a signal like this is typically sent  Any command line shortcuts or commands that are associated with them   Here is the list of signals and what I have so far.  0 - ?  1 - SIGHUP - ?, controlling terminal closed,  2 - SIGINT - interupt process stream, ctrl-C  3 - SIGQUIT - like ctrl-C but with a core dump, interuption by error in code, ctl-/  4 - SIGILL  5 - SIGTRAP  6 - SIGABRT  7 - SIGBUS  8 - SIGFPE  9 - SIGKILL - terminate immediately/hard kill, use when 15 doesn't work or when something disasterous might happen if process is allowed to cont., kill -9  10 - SIGUSR1  11 - SIGEGV  12 - SIGUSR2 13 - SIGPIPE  14 - SIGALRM 15 - SIGTERM - terminate whenever/soft kill, typically sends SIGHUP as well?  16 - SIGSTKFLT  17 - SIGCHLD  18 - SIGCONT - Resume process, ctrl-Z (2nd) 19 - SIGSTOP - Pause the process / free command line, ctrl-Z (1st) 20 - SIGTSTP  21 - SIGTTIN  22 - SIGTTOU 23 - SIGURG 24 - SIGXCPU 25 - SIGXFSZ 26 - SIGVTALRM 27 - SIGPROF 28 - SIGWINCH 29 - SIGIO  29 - SIGPOLL  30 - SIGPWR - shutdown, typically from unusual hardware failure  31 - SIGSYS


$\lim x_n^{x_n}=4$ prove that $\lim x_n=2$

Let $(x_n)$ be a sequence of real numbers, such that:  $\lim x_n^{x_n}=4$, prove that $\lim x_n=2$  I'm not sure if my proof is right.  I assumed that $\lim x_n $ isn't 2 and using Cauchy's criterion:  $|x_n-2|>\epsilon$  so $ x_n>\epsilon+2$  or $x_n<-\epsilon+2$  $|x_n^{x_n}-4|<\epsilon $ so $x_n<\sqrt[x_n]{\epsilon+4}$  and then we combine what we've found and get: $\epsilon+2<\sqrt[x_n]{\epsilon+4}$   $\epsilon+4<(\epsilon+2)^2<(\epsilon+2)^{\epsilon+2}<(\epsilon+2)^{x_n}<\epsilon+4$  and it's not true so  $\lim x_n=2$.  Is that okay?  Edit: I just wanted to know if my solution was right but the other post helped as well, thanks.


I need help on the pagination. I try to put the NEXT and PREVIOUS pagination that show the post in a same category, but I am not sure what happen that showing nothing.  If you can help, much thanks!

     <?php      $previous_post = get_previous_post('%link', 'Next post in category', TRUE);     if ( $previous_post ) : ?>
     <?php if ( has_post_thumbnail( $previous_post->ID ) ) : ?>     <?php echo get_the_post_thumbnail( $previous_post->ID, 'gallery-navigation' ); ?>     <?php endif; ?>     <a href="<?php echo get_permalink( $previous_post->ID ); ?>">

<?php echo $previous_post->post_title; ?>

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Hardware issue on iMac, flashing question mark

I have an iMac 2008/2009 issue and recently the computer would not boot and I would get a flashing question mark. Ran through all the usual steps, try boot in safe mode, flash RAM,  try single user for fdisk, put in OS disk and boot from CD, etc... No dice.   Replaced the hard drive and put the OS disc in the system, press and hold option. (holding C didn't work) I can see the OS disk but when I click on it the system will act like it is going to run and then freeze. The best I got was the OS X disc that changed the screen to dark grey and told be the system had to restart.  Purchased a usb mount for an external hard drive. Was able to mount the old hard drive to a laptop and run disk utility. Everything checked out.  At this point I am pretty sure it isn't the hard drive.   Any other hard ware items this can point too? My iMAC can also "see" the hard drive (and the recovery partition) when connected via the USB and I hold "option" on start up. But it crashes when trying to boot from either.  I am going to take out and re-install the RAM for giggles but I am not sure what else to do.   Ideas are welcome.


How to add output from a command to a group name in a script?

I'm manually creating a version of useradd, and at the moment what i'm trying to do is get the output of this command:  head -$1 /folder/file | grep $2 | cut -d ',' -f4   and input it into this command:  echo "$1:x:50$int" >> /etc/group   where $1 is. Basically the first command is pulling a companies name and I want to add it to a group. I already have a group id setup.


T-SQL Remove Zero Padding as String Manipulation

If you are dealing with strings as nvarchar and varchar in SQL Server what is the correct way to drop leading zeros without casting to an INT type?  Say '000123' for example. I would like to convert this into '123'


Discard mesh zones from solidify modifier

I would like to discard some zones from a mesh from solidify modifier, but I don't know how


What young adult SF book is about a boy saved by aliens and domed colonies?

When I was younger (lets go with probably about 20 years ago), I read a f/sf book that I've been looking for ever since, but I can't for the life of me rediscover it.  It centers around a boy who is rescued from (I believe) a flood, by aliens, who take him to a sort of a domed colony, populated by other humans saved from disaster.  The setting in this domed colony is more or less suburban, but there are robots that are considered caretakers, that keep it running, etc. (and actually, it turns out that the robots are the only ones left, and that their creators are not extant).  Over the course of the book, the boy travels to similar domed colonies that house other alien species.  In one, he comes across (this is a little fuzzy in my memory here) a fruit that enables transmogrification, which is used in an alien ritual of some sort.  The only other detail I can recall is that at the climax of the book, this fruit is used to become one of the robots' creators, in order to break into some sort of control center.  This has been bugging me for the better part of a decade - hopefully somebody here is familiar with this book.


How does the proof of Rejection Sampling make sense?

I am taking a course on Monte Carlo methods and we learned the Rejection Sampling (or Accept-Reject Sampling) method in the last lecture. There are a lot of resources on the web which shows the proof of this method but somehow I am not convinced with them.  So, in the Rejection Sampling, we have a distribution $f(x)$ which is hard to sample from. We choose a easy-to-sample distribution $g(x)$ and find a coefficient $c$ such that $f(x) \leq cg(x)$. Then we sample from $g(x)$ and for each draw, $x_i$, we also sample a $u$ from a standard uniform distribution $U(u|0,1)$.  The sample $x_i$ is accepted if it is $cg(x_i)u \leq f(x_i)$ and rejected otherwise.  The proofs which I came across usually just show that $p(x|Accept) = f(x)$ and stop there.   What I think about this process is that we have a sequence of variables $x_1,Accept_1,x_2,Accept_2,...,x_n,Accept_n$ and a $x_i,Accept_i$ pair corresponds to our i.th sample ($x_i$) and whether it is accepted ($Accept_i$). We know that each $x_i,Accept_i$ pair is independent of each other, such that:  $P(x_1,Accept_1,x_2,Accept_2,...,x_n,Accept_n) = \prod\limits_{i=1}^n P(x_i,Accept_i)$  For a $(x_i,Accept_i)$ pair we know that $P(x_i) = g(x_i)$ and $P(Accept_i|x_i) = \frac{f(x_i)}{cg(x_i)}$. We can readily calculate $p(x_i|Accept_i)$ but I don't understand how it suffices as a proof. We need to show that the algorithm works, so I think a proof should show that the empricial distribution of the accepted samples converge to $f(x)$ as $n\rightarrow\infty$. I mean, with $n$ being the number of all accepted and rejected samples:  $\frac{Number \hspace{1mm} of \hspace{1mm} samples \hspace{1mm} with \hspace{1mm} (A \leq x_i \leq B)}{Number \hspace{1mm} of \hspace{1mm} accepted \hspace{1mm} samples} \rightarrow \int_A^B f(x)dx$    as    $n\rightarrow\infty$.  Am I wrong with this thought pattern? Or is there a connection between the common proof of the algorithm and this?   Thanks in advance


Writing to txt file, Null pointer Exception

I am trying to write to a csv file however everytime i get a null pointer exception. The data i wanted written to the csv file is being written but i get the error and i cant figure out why.  public static void writeCsvFile() {     FileWriter fw = null;     VendingMachine vm = new VendingMachine("Conall", 10);     try {         fw = new FileWriter("stock.txt");         //fw.append("ID");         for (VendItem item : stock) {             fw.append(String.valueOf(item.getId()));             fw.append(",");             fw.append(item.getName());             fw.append(",");             fw.append(String.valueOf(item.getPrice()));             fw.append(",");             fw.append(String.valueOf(item.getPrice()));             fw.append("\n");          }     } catch (Exception ex) {         ex.printStackTrace();     } finally {         try {             fw.flush();             fw.close();         } catch (Exception e) {             e.printStackTrace();         }     }  }   My file has the following in it:  1,Coke,0.7,0.7 2,Fanta,0.6,0.6 3,Galaxy,1.2,1.2 4,Snickers,1.0,1.0 5,Dairy Milk,1.3,1.3 6,Kinder,1.3,1.3   How can i fix the null pointer error as it seems to be working as i am looking it to, i.e writing the files in my stock to this file.  Thanks for any help


Is the simulation of emotional states equivalent to actually experiencing emotions?

According to the  video, researchers have been able to develop an AI unit that is able to experience emotional states, such as greed, hunger, and curiosity. If the AI is currently experiencing an emotion, it will engage in certain behaviors. For example, if Mario is very greedy, Mario will look for coins. This approach is very similar to the Sims video game series, where emotional states are also represented, and AI characters will attempt to fulfill those drives.  Now, I can concede that the Mario AI is effective at simulating emotions. The media, however, has gone beyond this. Two articles, in particular,  troubles me.       I can accept the idea of Mario 'learning'. I can even accept the idea that Mario is 'self-aware' within his own environment. But I cannot intuitively accept the idea that Mario is feeling any emotions. It seems weird to think that EA programmers and German AI researchers were both able to accomplish the dreams of science fiction writers all over the world, and without anybody ever noticing.  Maybe my intuition is wrong though, and maybe Mario is indeed feeling emotions (even if they are not the same emotions as humans feel).


I am trying to make a program that creates an ArrayList given the type as well as the values that will be put into the ArrayList. The input structure that we have to work with is "I 6 7 5 3 1 -1 2" with the I being the type Integer (or S for String, etc) and the first number (6) being how many values are in the ArrayList. I'm not sure how to instantiate the ArrayList.  public static void main(String[] args){     Scanner scan = new Scanner(System.in);     String type = scan.next();     int length = scan.nextInt();     int counter = 0;      if (type.equals("I")) {         ArrayList<Integer> A = new ArrayList<Integer>;     }     else if (type.equals("S")) {         ArrayList<String> A = new ArrayList<String>;     }     else if (type.equals("D")) {         ArrayList<Double> A = new ArrayList<Double>;     }     else {         System.out.println("Invalid type");     }      while (scan.hasNext() && counter<length) {         String s1 = scan.next();         A.add(s1);         counter += 1;     }      System.out.print(A); }  //Removes any duplicate values in the arraylist by checking each value after it public static <E> ArrayList<E> removeDuplicates(ArrayList<E> list) {     ArrayList<E> inArray = list;     for (int i = 0; i<inArray.size(); i++) {         for (int j = i+1; j<inArray.size(); j++) {             if (inArray.get(i) == inArray.get(j)) {                 inArray.remove(j);             }         }     }     return inArray; }  //Shuffles the contents of the array public static <E> void shuffle(ArrayList<E> list) {     E temp;     int index;     Random random = new Random();     for (int i = list.size()-1; i > 0; i--) {         index = random.nextInt(i + 1);         temp = list.get(index);         list.set(index, list.get(i));         list.set(i, temp);     }     System.out.print(list);     return; }  //Returns the largest element in the given arraylist public static <E extends Comparable<E>> E max(ArrayList<E> list) {     E max = Collections.max(list);     System.out.println(max);     return max; }


When I import an OBJ it won't show up, does anybody know how to fix it?

When I try to import wavefront .obj, it won't show up. It appears in the explorer, but I can't see it when I try to edit. Does anybody know how to solve this?


So far, I could solve all my monitoring needs (like CPU and memory usage, network traffic, and disk activity) with ksysguard. It was what came preinstalled with KDE, it's easy enough to figure out, it is easy to adapt the display to whatever you're looking for, and with a bit of google & error I was able to set up ksysguardd on remote systems to do over-the-network monitoring, too. Being able to save log data to file was also useful.  Now, I would like to log such performance data on the remote server, i.e. without having a ksysguard instance running on a "monitor system" locally. I know that this should actually be easier than transferring the data over the network and displaying it in graphs and bars, but I honestly admit I am clueless.  Googling gave me links to several enterprise-level, everything-and-the-kitchen-sink solutions, but it seemed none of them would be quite as easy to set up and configure as ksysguard was (especially not without root access on the to-be-logged system), and I am not sure I am up to the task, and certainly not willing to invest more than 1-2 hours into the subject.  Can you people give me suggestions on simple performance logging solutions for Linux?  Edit: I should have mentioned, one of the core requirements is that the logging must be able to run without root access.


Calculating p-values for two tail test for population variance

A sporting goods manufacturer claims that the variance of string tensions for any decent tennis racquet should be about 9 pounds. The string tensions of 18 randomly selected tennis racquets produced a variance of 8.13 pounds. Find the p-value to test the manufacturer's claim (assume the population is normally distributed).  I tried attempting the question as follows: ${H_o}: {\sigma ^2} = 9$ ${H_1}: {\sigma ^2} \ne 9$ We are also given the following: $n=18$ $s^2 = 8.13$ Test Statistics: $\chi^2 = {{(n-1)S^2}\over{\sigma^2}}$ Calculating Test Statistics under $H_o$ gives us: $\chi^2 = {{(18-1)8.13}\over 9} = 15.35667$  For calculating the p-value I proceeded as follows: $p-value = 2\min\{P[\chi^2>15.35667],\ P[\chi^2<15.35667]\}\ =2\times 0.430192 = 0.860384$  I am not certain if my method for calculating the p-value is correct or not. Can someone please tell if the above process is valid?  Thanks in advance!


Will I require a transit visa to travel to Antigua from Gatwick

I will be travelling to Antigua to cover the first cricket test match between India and West Indies.  Will I require a transit visa as I have to change airport from Heathrow to Gatwick, as my flight to Antigua is from Gatwick?


How the speed of light is constant in the universe if it decreases in water and glass and some other objects?

My teacher told me that speed of light is constant in the universe. But in optics it is clearly shown that speed of light slows down in some objects. Please help.


I live in Vancouver on a working holiday visa, from Australia. I got a waiver form to go to the states, but just went for a day at the beginning of the year. This was the 90 day waiver and then "expired" in the beginning of April. I want to go to Seattle for the long weekend and Disneyland in July. Do I have to get a different visa? Or can I renew my visa waiver that was the 90 day one? If I renew it how?


how to download OS X El Capitan for MacBook Pro A1278

I have a Macbook Pro A1278 with a dead hard drive.  I have put a new hard drive in it and now need to figure out how to get my hands on the os.  Does anyone know if it is possible to still download OS X El Capitan?  If so, how?


If $m^4+4^n$ is prime, then $m=n=1$ or $m$ is odd and $n$ even

I have been stuck on this one for months, really simple to state, really giving me trouble.     Show that if $m^4 + 4^n$ is prime, $m>0$, $n>0$, then $m$ is odd and $n$ is even, except when $m=n=1$.   The case $m=n=1$ gives $5$, so that is why it is excluded. Clearly $m$ is odd, for if it was even, the number would be divisible by at least $4$, but I can't seem to get rid of the case where $n$ must be odd.   The only thing I've managed to try is to write $m$ as an odd number, say $m = 2k+1$, and $n = 2\ell + 1$, then get $$ m^4 + 4^n = (2k+1)^4 + 4^{2\ell+1} = 16k^4 + 32k^3 + 24k^2 + 8k + 1 + 4^{2 \ell + 1} $$ and this is congruent to $0 \mod 5$ unless $k \equiv 2 \mod 5$, and now it gives you an even more ugly polynomial if I write $k = 5j+2$, and it's not working. I've tried other inconclusive approaches, like trying to see if two numbers of some form generate numbers of the same form.. (for instance primes of the form 8k+1 and 8k+7 always generate primes of the same form when multiplied together, stuff like that).  Any ideas? Even just ideas you haven't gave a thought... they're welcome!


I JSON decode a page with PHP, but sometimes there's a name like 'M'gladbach' or 'Côte d'Ivoire' and then the SQL sees the first single quote as a stop so it gives me the error after the 'Côte d' Can somebody help me with this problem ? I know you can do 'Côte d''Ivoire' but as I get all the info from a API I can't put double quotes in it. Thanks a lot.


Poor recurrent neural network performance on sequential data

I have a dataset of energy measurements taken every minute from the energy footprint of home appliances. Based on that I am trying to detect human presence in the house. Since the data is sequential, I decided to use a recurrent neural network (LSTM) to model it.   Because the classes are unbalanced (~60/40) I am using confusion matrix metrics along with accuracy. The other main characteristic of the dataset is that it has a great deal of sparsity, especially in certain features.  I have a baseline of a deep feedforward network to compare the model against. During training of the feedforward variant I shuffle the dataset to return it to an iid setting and prevent overfitting.  I am using the negative log likelihood as my cost function in both cases. This is a binary classification setting so this, in turn, yields the binary cross entropy cost.  The feedforward network yields the following results:  accuracy: 86.37%  f1 score: 82.00%  precision: 82.98%  recall: 81.10%   The recurrent network, on the other hand, yields the following:  accuracy: 31.08%  f1 score: 38.35%  precision: 68.53%  recall: 58.34%   Clearly, the LSTM is performing significantly worse. My intuition is that it is overfitting the data (the training cost is decreasing steadily). I should mention that I do not shuffle the dataset during training of the LSTM, as I want to preserve the sequential structure of the data. Am I making wrong assumptions about training it? Should I actually shuffle the dataset? If that is not the problem, does anyone have any pointers on what could be going wrong?  I also thought sparsity is a problem but then again it doesn't seem to affect the feedforward variant too much.  Thanks in advance.


I regularly vote for deletion on "non answers". Sometimes I am too quick; and would prefer to undo that action.  But when I click delete again; I am told that I already voted here; so there is no way to retract a delete vote?  (in contrast to close votes or flags I put up?)


I am a computer scientist, and one of my professors today used the symbol $\propto$. I tried to search that using google, but it returns no results, and I do not even know its name.  So, I would like to ask, what does the operator $\propto$ mean? What is its name, and how is it used?


Installed QGis on macbook pro. If I needed to reinstall or modify a plugin, where is the plugins folder located?


Can anybody help me find a short story from the 70s about a musical prodigy chosen from birth?

I read a story in the 70s about a child that was predicted to be a musical genius and left alone with musical instruments and absolutely no outside musical influences. He eventually was exposed in some way to outside music and forbidden to play again.


In how many ways can a $31$ member management be selected from $40$ men and $40$ women so that there is a majority of women?

Here's the question:     In an organization there are $80$ people, $40$ men and $40$ women.   In how many ways can we choose, from those $80$ people, a $31$ member management so that there is a majority of women?    My answer was to first choose $16$ women (to assure the majority) out of the $40$ meaning $\binom{40}{16}$, and then choose the rest $15$ from the rest of all people meaning $\binom{64}{15}$. So the final answer is ${40 \choose 16} \cdot{64 \choose 15}$ but that isn't the right answer so I really don't know.. help? Thank you.    Note $\binom{n}{k} = \frac{n!}{k!(n-k)!}$, the binomial coefficient.


I'm trying to edit a file on a remote server via a terminal and to make a change in said file I have to (or have used so far) use the 'sed' command.  in the below file i want to delete the string STUFF_456 and its new line character.  STUFF_123 STUFF_456 STUFF_789   However when I use this command in sed i'm left with a blank line.  $ sed -i 's/STUFF_456//' /file/path/here.txt STUFF_123  STUFF_789   I need to get rid of the blank line and keep the other two entries.  How can I accomplish this?


This search seems to work much better than the search bar at the top:    In fact, this is the way I normally search. Is there anyway the way this search works could be incorporated into the main search bar?


How to explain this kind of falacy about Monty Hall problem?

I have no doubt that the probabilities are $2/3$ by switching; my problem is trying to explain it to someone. His first point is the two choices are unrelated events. My argument is:  $1$) If at first you chose a door with a goat ($2$ cases of $3$), then for the second choice you will have a goat in your door and the car in the other. You win by switching.  $2$) If at first you chose the car door ($1$ case of $3$), then for the second choice you will have the car in your door and a goat in the other. You win by staying.  Textually, what he answered was: (He calls $E1$ to the first event, ie to the first selection, and $E3$ to the second selection)  "You could not have picked a Goat or Car in E1, it's impossible, the Game assigns no value to Your E1 pick, it's an unknown by Game definition.  What is known is the Value of each Door in E3.  The difference in definition between E1 as a Constant or E1 as a Variable is the crux of the issue. All previous definitions of The Monty Hall define the Result of E1 as Variable.  The Value of E1 is irrelevant. E1 as a Constant is why E3 is an independent event. With Odds calculated as Roulette, not as BlackJack."  The important thing about his argument, which I had not seen from other people, is that he thinks that the fact that you can not see what is behind the first door picked makes it completely irrelevant, and so the two choices are separated events.


Cleaning my Macbook Pro Retina leaves greasy 'streaks' across the screen

I try to clean my mid-2015 Macbook Pro with Retina display by wiping the screen with a damp cloth and then immediately drying.  However, there seems to be left some residue/streak marks, which look very oily. Sometimes these disappear after a few minutes, but they are still very unsightly, and a bit worrying (is there something wrong with my screen?)  I'm wondering if there are other cleaning techniques which avoid this issue, or whether this is completely normal behaviour.  Thank you!


Bug with class variable highlighting in Ruby code blocks

It appears that Ruby class variables aren't fully highlighted on Stack Overflow:  class Foo   @class_instance_var = 1 # fine   @@class_var = 2         # not fully highlighted end   The class instance variable gets full highlighting, but the double @ seems to throw the highlighter a bit.   Here's an SO question with this in action:   Update: 5th April  I've , with a patch that appears to solve the problem. Thanks to @CodyGray for the information.


Exponent font size change when using overbrace

Looking at the MWE below, the fontsize of the last exponent got enlarged after applying \overbrace. How to get its size back to the original as if the overbrace weren't there? Thank you!  \documentclass{article}  \begin{document}  \[     e^{-t/\tau} + e^{-\overbrace{t/\tau}^{\theta}} \]  \end{document}


I'm trying to learn how RSA works. From what I found online, I'm supposed to  generate private key using Extended Euclidean algorithm.  I've managed to generate the public key, but don't know how to use EEA to generate the private key. How should I exactly input into EEA, and how to process the output?


What's the difference between have/has been and was?

English is my second language and I have always been confused with 'have been/has been' and the idea that it could be replaced with 'was' in some contexts.  For instance, this is a part of an urgent email about a bomb threat:     An unconfirmed bomb threat has been received. The halls are being evacuated. More info to follow.   My doubt is: why couldn't it be 'was received' and what that would change?  Another example:     The thumbnails base has been updated.   Many times, I see 'have/has been' in something that could be 'was' from my understanding.  This is a question I have been asking myself for a long time.  I would appreciate if someone could help me.  Thank you!


I installed a program by getting its source code, and then running `sudo make install`; how to make `apt-get` know about it?

I installed program (call it, for example,progA) by building it from source code, and then finally calling sudo make install and sudo ldconfig.   However, it seems apt-get hasn't gotten the memo, because when installing progB, which depends on progA, apt-get recommends I also install progA. Why is this, and what could I do?


Calculate using integration by parts $\int \frac{x^2}{(x^2+1)^2}\,dx$

Calculate using integration by parts $$\int \dfrac{x^2}{(x^2+1)^2}$$   I'm looking through some working for this question and it gives  $u=x/2, u'=1/2$  $v'=\dfrac{2x}{(x^2+1)^2}, v=\dfrac{-1}{x^2+1}$  I'm confused as to why these values for u and v are used and would appreciate it if someone could explain why


How to increase the time needed before "Page(s) Unresponsive" show? (Chrome)

To prevent annoyance with Chrome's persistent "Page(s) Unresponsive" popup, I've disabled them using .   However, this has the effect of allowing a true webpage hang to simply hang forever. It simply refuses to close unless I force-quit using task manager (which is not a good idea as many other tabs will end up getting killed along with it).  Is there a way to make the "Page(s) Unresponsive" popup show after a very long delay, for example after a page has hanged for 10 minutes or more?


So I'm pretty new to electronics, and I'm getting slightly hung up on the concept of ground. I'm thinking the circuit diagrams below will help me to explain this frustration, because there's not an intuitive explanation as to why these two diagrams are identical.   I'm just going to spew what I believe is correct, and hopefully I get some stuff wrong and learn along the way.    Looking at the rightmost diagram:  My intuition is that (since these are 0V reference points, not actual ground connections) if electrons flow out of the negative terminal of the battery there needs to be a connection to the right 'ground' in order to keep it at 0V relative to the left ground.   Expanding on that, does that mean every 0V reference point can be thought of as being connected by a wire. So if I had 50 more 0V reference points, throughout some complicated circuit, all of them can be thought of as being connected? Thus simplifying any circuit with multiple 0V reference points to only one 0V reference point?  Question: What is the point of doing this? Is it just to reduce the complexity of circuit diagrams later on? Because right now it definitely complicates the one below.   Secondly, say instead of 0V reference points, those ground connections are actually earth ground connections.   The reason why current would instead flow to the negative terminal of the battery is because it's more attracted to that then the neutral ground. Does any minuscule amount of current leak to ground? Also, in the same sense as before, can we think of each individual 'earth' ground in the right diagram as connected?  Thank you!


How big would the moon appear with no atmosphere?

I know that atmospheric lensing is what causes the moon to look bigger on the horizon, but I assume this effect is still taking place when the moon is overhead too, albeit to a smaller effect. However, would the moon appear to change in size if you looked from an earth with no atmosphere?


Why is my database still fragmented after I rebuilt and reindexed everything?

I have a database which I tried to defragment all the tables at once by running this T-SQL:  SELECT          'ALTER INDEX all ON ' + name + ' REORGANIZE;' + CHAR(10) +         'ALTER INDEX all ON ' + name + ' REBUILD;'     FROM sys.tables   And then copying and pasting the output to a new query window and running that. I got no errors, but I still have fragmentation. I tried running both commands separately too and still have fragmentation. Note: I have been made aware that REORGANIZE is unnecessary by Aaron, and I'm aware I could use dynamic sql to automate this.  I ran this to determine I still have fragmentation:  SELECT * FROM  sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, NULL)  WHERE avg_fragmentation_in_percent > 0   And I got:  database_id object_id   index_id    partition_number    index_type_desc alloc_unit_type_desc    index_depth index_level avg_fragmentation_in_percent    fragment_count  avg_fragment_size_in_pages  page_count  avg_page_space_used_in_percent  record_count    ghost_record_count  version_ghost_record_count  min_record_size_in_bytes    max_record_size_in_bytes    avg_record_size_in_bytes    forwarded_record_count  compressed_page_count 85  171147655   1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   36.3636363636364    5   2.2 11  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  421576540   1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   75  7   1.14285714285714    8   NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  965578478   1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   14.7058823529412    6   5.66666666666667    34  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1061578820  1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   40  4   1.25    5   NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1109578991  1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   30.7692307692308    5   2.6 13  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1205579333  2   1   NONCLUSTERED INDEX  IN_ROW_DATA 2   0   50  5   1.6 8   NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL 85  1493580359  1   1   CLUSTERED INDEX IN_ROW_DATA 2   0   50  6   1.66666666666667    10  NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL    NULL   I know I am missing something real basic, but I don't know what.


Is it OK to borrow a ground wire from a different circuit?

I've got a circuit in the basement carrying a handful of outlets.  This circuit has no ground wire.  I want to add a couple of outlets and want them to be grounded.  I may even want gfci outlets on them in the future.  I have no reasonable way of getting a ground wire to the panel but I do have easy access to another circuit that does have a ground wire.  Is it acceptable to borrow or share a ground wire between circuits?  If not, why not?  Both circuits are 20A with 12 AWG wire.


Can someone explain Gibbs sampling in very simple words?

I'm doing some reading on topic modeling (with Latent Dirichlet Allocation) which makes use of Gibbs sampling. As a newbie in statistics―well, I know things like binomials, multinomials, priors, etc.―,I find it difficult to grasp how Gibbs sampling works. Can someone please explain it in simple English and/or using simple examples? (If you are not familiar with topic modeling, any examples will do.)


How to make sense of a photon time and space being dilated infinitely?

For a photon or anything that travels at the speed of light, time is dilated infinitely, meaning there is no time. Also, length along the direction of motion is dilated infinitely, meaning the length of the universe along that direction becomes zero. Is this interpretation correct? How do you make sense of this? Does it mean that the photon is omni-present at all times and places? Does this imply some kinds of connection with field theory, where it becomes a field that is just present everywhere?


Counting ring homomorphisms from $\mathbb{Z}[x,y]/(x^3+y^2-1)$ to $\mathbb{Z_7}$

How many ring homomorphisms there is between $\mathbb{Z}[x,y]/(x^3+y^2-1)$ and $\mathbb{Z_7}$? Here $\mathbb{Z_7}$ denote ring of integers mod 7.  I don't know how to approach this problem,so far I've only worked with one variable ring so I can't tell the properties of $\mathbb{Z}[x,y]/(x^3+y^2-1)$. Thanks in advance


If a local ring is $\mathfrak{m}$-adically complete is it also $I$-adically complete

Suppose $(R,\mathfrak{m})$ is a local ring and $I$ a proper ideal. If $R$ is $\mathfrak{m}$-adically complete is it also $I$-adically complete.


I got a OutOfMemoryError when adding a object to an ArrayList of objects

OUT OF MEMORY ERROR ON THE LINE THAT ADDS THE OBJECT TO THE ArrayList - LAST LINE  I want every time I click the button saveScore, the name of the first team selected from the first spinner, the name of the second team selected from the second spinner, the score from the first editText  and the score from the second editText to be the arguments of my class object.  teamOneScore & teamTwoScore are two EditText where I enter the score for each team selected from the spinners and arrList is my ArrayList of objects .  I have a class - TeamsViewModel with 4 members of type String:  team1Name, team2Name, team1Score, team2Score.   saveScore.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View view) {         boolean resultAddTeamOneScore = addTeamOneScore(weakActivity, teamOneScore.getText().toString().trim(), teamTwoScore.getText().toString().trim());         boolean resultAddTeamTwoScore = addTeamTwoScore(weakActivity, teamTwoScore.getText().toString().trim(),teamOneScore.getText().toString().trim());       if (resultAddTeamOneScore && resultAddTeamTwoScore) {           dialog.dismiss();           }       /** save the teams selected from the spinner */      String selectedT1 = teamOneSpinnerSelected(teamOneSpinner);      String selectedT2 = teamTwoSpinnerSelected(teamTwoSpinner);      while (!selectedT1.equals(selectedT) {         /** add to the ArrayLists of objects the teams selected and their's score*/         arrTeam.add(new TeamsViewModel(selectedT1, teamOneScore.getText().toString().trim(), selectedT2, teamTwoScore.getText().toString().trim()));                     }                 }             });


I am new to ubuntu world...   How to install vivaldi browser on ubuntu? How could we find dependencies, when installing any software on ubuntu?


What's a good book for a beginner in high school math competitions?

Also, I want to make it clear: Beginner.  I'm getting really frustrated trying to study for math competitions:   On the one hand, there are books teaching the high school curriculum, but that's it. I don't need these, I know (almost) everything on your regular high school curriculum. On the other hand, there are books for the IMO. But they assume you have a really strong olympiad mathematics background, and they are only there to prepare you for the IMO. They're basically composed of one or two lines of theory per chapter, and then a huge list of hard exercises and problems. I don't need these either: I'm not even near the IMO calliber, and the solutions to the problem seems to rely on theorems and techniques that aren't taught in high school.   What I am really looking is for a bridge between these two extrema: A book that makes a connection between high school basic math and IMO advanced math.  A book that covers  is what I am trying to find. I've never heard about any of these topics, though they seem to be essential for math competitions. Also, I've never found any book that covers them.   I'm not sure whether a single book will contain such a broad range of topics, so I believe that I'll need a book for Algebra, a book for Number Theory, a book for Combinatorics, etc.   But if that's the case, I also want to make it clear that I'm not looking for a book that teaches you college Algebra, college Number Theory, etc. I want something that covers topics that appear on a math competition, but doesn't assume anything other than high school maths.  Thank you in advance.


Product of an exponential function of IDD variables

if $x_i$ are IID  continuous random variables, with $E[x_i]=μ$, is the following correct?   $E\left[\prod_{i=1}^n(1+⍺\space x_i)^i\right] = \prod_{i=1}^nE\left[(1+⍺\space x_i)^i\right] =  \prod_{i=1}^n(1+⍺\space E\left[x_i\right])^i = (1+⍺\space μ)^n$  thanks!


Questions every good .NET developer should be able to answer?

My company is about to hire .NET developers. We work on a variety of .NET platforms: ASP.NET, Compact Framework, Windowsforms, Web Services. I'd like to compile a list/catalog of good questions, a kind of minimum standard to see if the applicants are experienced. So, my question is:  What questions do you think should a good .NET programmer be able to respond?  I'd also see it as a checklist for myself, in order to see where my own deficits are (there are many...).    *UPDATE: It want to make clear that we're not testing only for .NET knowledge, and that problem solving capabilities and general programming skills are even more important to us.


I was able to get 18.04 installed and working. The problem is now it freezes after some non-specific time or thing i do. Machine is ASUS Fd503VX with GTX1050. I have not installed the Nvidia drivers yet (usually does not go well). Do i need to do this, is this causing the issue? I did install the synaptic mouse driver (seems to be better). When it freezes terminal still works but cannot move the mouse (this is why i installed Synaptic).  If i do need the Nvidia drivers is the a recommended post to do this, as i when i search there are many methods. My recommended is Nvidia-drivers-390. not sure if prime or bumblbee are still needed. Last laptop i jsut gave up on Nvidia.


Why is ubuntu shutdown so fast compared to Windows 7

I have installed Windows 7 64 bit and Ubuntu 10.10 32 bit on my machine. The partition sizes are 400 GB and 100 GB receptively. I've always wondered how Ubuntu shuts down so fast? It takes only 5 seconds or less whereas Windows 7 takes a lot longer.   Although, I have more programs installed on Windows 7, but still its shut down time was much more than that of Ubuntu during first month of install. It was 10-15 sec approx. I'm not counting the time used for installing updates sometimes, when shutdown is clicked in Windows 7.  What makes Ubuntu shutdown and boot(faster than Windows 7 but not by wide margin) so fast. Is it the file system? will it be other way around if I had swapped partitions spaces(Can't try this now)? Sorry I don't have Computer Science background, so don't know detailed structure and architecture of OS. Any pointers to this will help me cure my curiosity.


This is a very generic question regarding hotel checkout times and rent payment. Hotel websites usually list their rooms' price range based on how many nights the guest will be staying there. So if I were to check-in at about 5'o clock in the morning and vacate at 4 in the afternoon on the very next day, for how many days do I have to pay the rent for?  I am currently assuming this counts as 2 days, but I am not sure. Since I have to book it online, I must choose the number of days before paying (1 day is expensive enough). Is there a commonly expected check-out time for hotels? Please don't ask me where I will be staying - like I mentioned, this is a very generic question.  I called the reception, but I didn't get what they said (tough accent). There is no time for email either.     Check-in   December 01, 05:00 AM   Checkout   December 02, 04:00 PM


what software has been used to write annotations on this pdf?

Here it is the screenshot, clicking on the ballot there appears the annotation. I already tried okular but I'm not able to reach the same result (actually to save annotation I have to export the pdf as Document Archive, which makes it unreadable for every other pdf reader)    I opened it with Document Viewer


json.encode() not returning anything in mysql/php

My code looks like this:  $hostname = 'myhost.com'; $database = 'heading'; $username = 'me'; $password = 'pw'; $dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password); $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); $sql = "SELECT * from mytable"; $result = $dbh->query($sql)->fetchAll(PDO::FETCH_ASSOC); //var_dump($result); //This works and dumps the array with the right data header('Content-type: application/json'); echo json_encode($result);   This echos nothing back though. No errors, just nothing. If I try echo($result) this echos "Array".   What's happening here?


Regex to include product category pages but not product pages and pages without parameters

What Regex can I use that includes ONLY the first option below, excluding the other two?   www.site.com/products/category_name www.site.com/products/category_name/ www.site.com/products/category_name/product_name   I've tried ^www.site.com/products/(.*)[^/]$ but it also takes the last option as valid.  On the other hand, what Regex can I use to include the first URL below and exclude the second one with parameters?   www.example.com/en-gb/category/example-of-product  www.example.com/en-gb/category/example-of-product tduid=5758f21169858a7e15da57791c070f0d   Many thanks!


Can I specify an output path into the TeX file for generated PDF?

I'm using TeXstudio and I defined my command to copy the generated  PDF into another directory:  cmd /C copy %.pdf C:\Users\me\myLatex\pdf   and all works fine.  Now I would like to specify the output path into the .tex file; namely, I would like to do this:   cmd /C copy %.pdf outputDirectory   and in the TEX file something like (the following line does not make sense, is just to explain what I want to do):  \define outputDirectory = C:\Users\me\myLatex\pdf    in order to specify different output path for each document.


How can I calculate date difference between two dates in years?  For example: (Datetime.Now.Today() - 11/03/2007) in years.