Namespaces and Operator Overloading in C++

When authoring a library in a particular namespace, it's often convenient to provide overloaded operators for the classes in that namespace.  It seems (at least with g++) that the overloaded operators can be implemented either in the library's namespace:  namespace Lib { class A { };  A operator+(const A&, const A&); } // namespace Lib   or the global namespace  namespace Lib { class A { }; } // namespace Lib  Lib::A operator+(const Lib::A&, const Lib::A&);   From my testing, they both seem to work fine.  Is there any practical difference between these two options?  Is either approach better?


Is "And every time the ladies pass they be like 'Hi Will'" correct grammar?

In the  by Will Smith it says:     And every time the ladies pass they be like "Hi Will"   Is this correct grammar? I wonder because I thought that one should either change "be" to "are" or add "will" after "they" (so that it's "they'll be like ...").


Why doesn't this regex capture reach the end of the string?

I have some text, a block with address and phone numbers, that looks like:  import re text = 'John Doe Inc - Real Estate Brokers\n1234 Shaky Bridge Road, '\        '\n Suite 123, \nDallas, TX 12345\n\nTel: 123-456-7890\n\t\t'\        '\n\t\tCell: 234-567-8901'   I just want to keep everything before "Tel:" (i.e. the address, not the phone numbers).  I tried removing "Tel:" and everything after it.  re.sub('Tel:.*','',text)  # Returns: # 'John Doe Inc - Real Estate Brokers\n1234 Shaky Bridge Road, \n Suite 123, \nDallas, TX 12345\n\n\n\t\t\n\t\tCell: 234-567-8901'   However, this only removes "Tel: 123-456-7890".  The substring that is removed does not extend through the end of the string.  Why is that, and how can I fix it?


Basic question about $\sup_{x\neq 0}{} \frac{\|Ax\|}{\|x\|} = \sup_{\|x\| = 1}{\|Ax\|} $, $x \in\mathbb{R}^n$

I am having trouble with understanding the following definition while studying some basic things related with matrix norms:  For every matrix $A\in M_n(\mathbb{R})$  $$\sup_{x\neq 0}{} \frac{\|Ax\|}{\|x\|} = \sup_{\|x\| = 1}{\|Ax\|},\; x \in\mathbb{R}^n$$  Why we are taking $\|x\| = 1$?  Is there any proof of above statement?  Added: Why to take sup in the definition of norm?  I need help to understand above mentioned fact.   Thank you very much.


finding all finite fields making $x^2+x+1$ irreducible

Find all finite fields making $f (x)=x^2+x+1$ irreducible.  Obviously, we have only two cases:   For each prime $p $, $f $ is reducible over $\mathbb {F}_p $. Then, for any $n\ge 1$, it's reducible over $\mathbb {F}_{p^n}. $ $f $ is irreducible over $\mathbb {F}_p $. Then, since the deg of $f $ is 2, $f $ is reducible over $\mathbb {F}_{p^{2n}} $ if $n\ge 1$.   So it suffices to classify the cases $\mathbb {F}_p. $ From a direct observation, $f $ is reducible over $\mathbb {F}_p $ iff $p $ is a factor of $n^2+n+1$ for some integer $n $. Can I reduce it more? I wonder if $f $ is reducible over $\mathbb {F}_p $ iff $p$ has the form $n^2+n+1$.


Does anyone knows how to hide the emitting source of particles but show the particles only. I am using hair Type emitter, and particles are emmited from the vertex as reference location. I don't want to use the particle instance modifier because of the memory usage


Is it possible to recover a computer from a failed BIOS update?

While attempting the update the BIOS on an Asus motherboard, i learned the Asus Update Utility for Windows doesn't fully support Windows 64-bit.  It was able to erase the BIOS without problems, but failed to write the new BIOS. i knew that when i next rebooted the computer: it would be a brick.  When i rebooted the computer, it was a brick. But before i rebooted i transferred the bios backup, the new bios, and Asus DOS-based flash utility to another computer. Now the problem is how to fix it.  This Asus motherboard has a fail-safe bios recovery called Crash Free BIOS, where you put in a floppy or USB stick containing a file called p5b.rom and it will restore the bios from that file. But that doesn't work.  Is there any way to unbrick the machine?


Is it possible to have f.lux (software that adjusts display's color temperature) on Ubuntu 14.04?

f.lux is software which adjusts temperature of your display according to time of the day. Is it possible to make f.lux work in Ubuntu 14.04? If so, maybe you can share your knowledge or point me to a guide.


Prove that $\left|\frac{z_1-z_2}{1-z_1\bar{z_2}}\right|\lt 1$

Question: Prove that $\left|\dfrac{z_1-z_2}{1-z_1\bar{z_2}}\right|\lt 1$ if $|z_1|\lt1$, $ |z_2|\lt 1$    My solution:  I had no idea how to go about this one so instead I started simplifying the inequality and my solution is as follows:-  $$\begin{equation} \left|\dfrac{z_1-z_2}{1-z_1\bar{z_2}}\right|\lt 1 \\ \implies \left|\dfrac{z_1-z_2}{1-z_1\bar{z_2}}\right|^2\lt 1 \\  \implies \left( \dfrac{z_1-z_2}{1-z_1\bar{z_2}}\right)\overline{\left({\dfrac{z_1-z_2}{1-z_1\bar{z_2}}}\right)} \lt 1 \\ \implies |z_1|^2+|z_2|^2 \lt 1 +|z_1|^2|z_2|^2 \\ \implies (|z_1|^2-1)(1-|z_2|^2) \lt 0 \end{equation}$$  Now as $|z_1| \lt 1$, so $(|z_1|^2-1) \lt 0$ and similarly $(1-|z_2|^2) \gt 0$, hence we can safely conclude that the above inequality holds.    Whats my question about:-  Now the book that I am solving from also gave the same solution it just further factored $(|z_1|^2-1)(1-|z_2|^2)$. This doesn't seem a good enough proof for me. If anyone can suggest a proof which doesn't simply verify the statement to be proved.    P.S.:- This question has also been asked , but I don't think I have the same query as the OP of that post.


I need to do a polynomial interpolation of a set $N$ of experimental points; the functional form I have to use to interpolate is this:  $$ f(x) = a + bx^2 + cx^4,$$ as you can see the coefficient that I need to find are just 3: $a, b, c$; however the points I have are $\#N>3$ and so it looks like the determination of the coefficients is impossible because is over-determined. Does anyone have an idea of what should be done in such case (supposing it is even possible)?


String parsing: Extracting the filename from a URL

This is a link I have in a column of a table:  http://earthexplorer.usgs.gov/browse/etm/1/11/2000/LE70010112000130KIS00.jpg   There are like 1000's of rows like this.    Is it possible to extract the FileName like LE70010112000130KIS00 (without the path and filename extension) and put it in another column?    I am new to SQL Server.


I want to begin 3 (not 1) in enumerate environment  My Code  \documentclass{article}  \begin{document}  \begin{enumerate}     \item Three     \item Four     \item Five \end{enumerate}  \end{document}   Thank in advance


How does an electron manage to constantly revolve around the nucleus of an atom forever?

When an electron revolves around the nucleus of an atom is it using any energy  in doing so. If so, where does this energy come from and how does it be a constant source (the electron revolves forever)? What is the energy being used and how is it not getting over?


How do I list all packages outside of the enabled repositories?

I upgraded ubuntu, and since every PPA is disabled by default, I want to be able to list all packages that I have installed but aren't inside any enabled repositories. I want a command (or a series of commands) that performs a similar function as pacman -Qm on ArchLinux.


How to rollback after wrong update statement in sql server 2008R2?

select * from aa  update aa set City='chennai',LastName='vinoth';  ID  FirstName  LastName  City 29  Abcrdrr    vinoth    chennai 1   John       vinoth    chennai 2   Joe        vinoth    chennai 35  raja       vinoth    chennai 38  Johsdfgn   vinoth    chennai   I have wrongly updated Lastname, City columns in all the rows. Now I want to rollback to the old table rows.   Using SQL-Server 2008R2.


Use old laptop as additional screen with Windows 8

In the past, I've used  to use a laptop's screen as an additional monitor for my primary computer. It works great, and I'm quite pleased with it.  However, I've now upgraded to Windows 8, and Maxivista doesn't support that version of Windows. I've done some searching and have not been able to find any utility like Maxivista that supports Windows 8. The only Maxivista-like utility I've found is "Zonescreen," which also does not support Windows 8. Does such a utility exist for Windows 8?  Note that I am not talking about desktop mirroring or a software KVM. I've found apps like VNC and Synergy that allow you to do those things, but I'm looking to extend my desktop.  I've searched here on Superuser.com and I see quite a few questions about this, all related to Windows 7 and earlier.


What flag silences GCC's warning about no newline at file-endings?

I just read  about why new-line warnings exist, but to be honest my team has people working on several different platforms and with several different editors (everyone uses what bests suites them), so the warning has become ubiquitous, and since its not really a warning worth taking care of it's become noise and makes finding serious warnings a hassle.   Many times important warnings have gone unnoticed because, people got used to having a gazillion useless warnings pass by, so they obviously just stop looking at them carefully, and with reason IMHO. One could say in our case GCC is crying wolf too much for anyone to take it seriously anymore, which is a bad attitude but its just human nature.   Right now we compile with -Wall, because we want warnings, but is there a counter flag to avoid the new-line warnings?  Note: I Looked through the manual a bit but didn't find the answer in any place obvious so I gave up.  Note: In response to Robert Gamble's totally reasonable solution, our code is cross-platform and we have people and builds on Linux, Solaris and Windows, so the new-line... is not under consensus. And Somebody's compiler is always going to cry-wolf. Because there are over 40 developers, and other non programmer staff as well.


I am trying to understand how template classes work, but I keep getting compile issues

I am trying to better understand how template classes work. I thought that once you declare a templated class object in main, you pick the type that you want. Then when you call the function, you pass in the same value and the compiler will recognize what type you want. When I create the class I get ld: symbol(s) not found for architecture x86_64. I know there is something I am missing but I cant figure it out. If anyone could help that would be greatly appreciated. main.cpp #include "dynamicStack.h"  int main() {  dynamicStack<string> str;  str.push();  return 0; }  dynamicStack.cpp #include "dynamicStack.h"  template <class T> void dynamicStack<T>::push() {    cout << "Hello "; }  template <class T> dynamicStack<T>::dynamicStack() { }  template <class T> dynamicStack<T>::~dynamicStack() { }  dynamicStack.h #ifndef __DYNAMICSTACK_H_INCLUDED__ #define __DYNAMICSTACK_H_INCLUDED__ #include <iostream> #include <string> using namespace std;  template <class T> class dynamicStack { public:   dynamicStack();   ~dynamicStack();    void push();  private:    T data; }; #endif  ERROR: Undefined symbols for architecture x86_64: "dynamicStack<std::__cxx11::basic_string<char, std::char_traits, std::allocator > >::push()", referenced from: _main in cccQUr0w.o "dynamicStack<std::__cxx11::basic_string<char, std::char_traits, std::allocator > >::dynamicStack()", referenced from: _main in cccQUr0w.o "dynamicStack<std::__cxx11::basic_string<char, std::char_traits, std::allocator > >::~dynamicStack()", referenced from: _main in cccQUr0w.o ld: symbol(s) not found for architecture x86_64 collect2: error: ld returned 1 exit status


I have Ubuntu 18.04 and python 3.7. uname -a Linux username-laptop 4.15.0-109-generic #110-Ubuntu SMP Tue Jun 23 02:39:32 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux  When I run sudo apt-get update I get this error : E: The repository 'http://dl.bintray.com/aluxian/deb stable 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. E: The repository 'https://dl.bintray.com/aluxian/deb dev 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.  I tried  solution but I am also unable to open Software and updates.


Is there any way to play GIFs with Windows Photo Viewer?

Is there any way to play GIFs with Windows Photo Viewer or with Picasa Viewer in Windows 7 when Internet Explorer isn't my default browser?


How do I transpose a row to a column in a tab-delimited file?

I have a tab-delimited file with a number and the names belonging to the same number on the same row. The number and names are separated by a tab. The names are linked with each other by 2 underscores (__). It looks like this:  33  Hhe.1__Hhe.2__Hhe.3__Hhe.4   I would like to convert it (by using the command line) to this output:  33  Hhe.1 33  Hhe.2 33  Hhe.3 33  Hhe.4


To prove triangle inequality for $d : \mathbb C \times \mathbb C \to \mathbb R$ ; $d(x,y):=\frac {|x-y|} {\sqrt{1+|x|^2}+\sqrt{1+|y|^2}}$

Is the function $d : \mathbb C \times \mathbb C \to \mathbb R$ defined by $d(x,y):=\dfrac {|x-y|} {\sqrt{1+|x|^2}+\sqrt{1+|y|^2}}$ a metric ? I can easily prove it is symmetric and positive-definite ; but cant make any headway towards the triangle inequality . Please help


Is using a HTML required attribute on an input considered validation?

Im currently working on a register form, and I decided to add some required fields, like email, password etc..  The only validation i want to do on the required fields is simply not null, so i used the required attribute inside of an input element.  Is this safe? Or do i need to use additional PHP validation?


How can I install AMD Graphic Drivers on Ubuntu 18.04

I had always been a Windows user, Three days ago, I decided to start working with Linux Ubuntu 18.04. I had read in forums that they recommend it to new users.I downloaded it and installed it.  I search AMD drivers for ubuntu 18.04 , but i find my AMD drivers only for old version on ubuntu.  Can you help and learn me how to install AMD graphics driver on ubuntu 18.04 step by step please. Thank you !!  lspci -nn | grep -E 'VGA|Display'  00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics 620 [8086:5916] (rev 02) 01:00.0 Display controller [0380]: Advanced Micro Devices, Inc. [AMD/ATI] Topaz XT [Radeon R7 M260/M265 / M340/M360 / M440/M445] [1002:6900] (rev c3)


How come $32.5 = 31.5$? (The "Missing Square" puzzle.)

Below is a visual proof (!) that $32.5 = 31.5$. How could that be?    (As noted in a comment and answer, this is known as .)


How to reboot system into recovery mode in Ubuntu 14.04

How can I reboot the system into recovery mode? When I googled it, I saw that I should press and hold the F8 key and then I will get into the grub menu,where I can chose recovery mode, but I tried that and it's not working.


How to Latex without error text with emoji included?

I'm reading output from where users put their own input into a latex document. It appears as though the users can include emojis. So my question, what is then minimal needed so that the following MWE will latex without error. Either the emoji is correctly handled or else ignored or even replaced by some box. The important thing for me is that the document latexs without error. \documentclass{article}  \begin{document}      Can this be handled in latex?   👍      \end{document}


Check if listbox.SelectedIndex == listbox.Items.Count from BackgroundWorker

I have to check if a listbox's SelectedIndex is at the last index from a BackgroundWorker, but since I'm checking the listbox (which is on the GUI thread) from the BackgroundWorker I get this error:      System.InvalidOperationException: 'Cross-thread operation not valid: Control 'listBox1' accessed from a thread other than the thread it was created on.'   This is my code:  if (listBox1.SelectedIndex == listBox1.Items.Count) { //code here }   How could I make this if statement work without being on the GUI thread?


What is the dual space of $C([0,T];X)$ ($X$ Hilbert space)?

What is the dual space of  $C([0,T];X)$, where $X$ is a Hilbert space? Is it $\operatorname{BV}([0,T]; X^*)$?  As we know, for $C([0,T])$, the dual space is $\operatorname{BV}([0,T])$,  but when it is continuous with vector values in $X$, is it still true?


Is it possible to get PdfEdit running on Ubuntu 12.10 using qt3to4?

is pretty much the only FOSS low-level PDF-editing tool out there. It's pretty useful, and pretty recent since it's updated in 2012.  However, it's a shame that packages are nowhere to be found, and I cannot get it to compile from  on recent distro's.  Aparently, this software uses an ancient form of Qt called Qt3. In order to build Qt3 apps on Qt4 systems, there is this library called libqt4-qt3support and this tool called qt3to4 in the package libqt4-dev-bin. The idea is to convert the source code and compile the source with qt3-support.  I know nothing about Qt, but the basic idea is this, while in the root directory of the project.  Convert the Qt3 source to Qt4:      qt3to4 -alwaysOverwrite ./src/gui/*   Remove the Qt3 check from configure by commenting the check out:  nano ./configure  #       isqmake3=`$testbin --version 2>&1 | grep '3\.[0-9][0-9]*\.[0-9][0-9]*'` #       if test -z "$isqmake3" #       then #               testbin="" #       fi   Configure:    ./configure   Make:  make && sudo make install   But make quits with an error:  ... make[1]: Leaving directory `/tmp/pdfedit/src' make: *** [source] Error 2   So, does anyone have the knowledge to make this work? It would be awesome. We can then apply this to other packages as well. And we can finally answer . :)


Difference between "continue to" and "are continuing to"

Please tell me is there any fundamental difference between the two sentences:   Even today, people continue to use cheques.  Even today, people are continuing to use cheques.    I mean is there a difference as in time period (i.e when the action starts and when it ends). Or are the two sentence just the same and interchangeable?


Finding the latex-command for a character

How can I write  in latex? Which command should I use?


A Riemann integrable function must have infinitely many points of continuity

I was wondering whether anyone would be so kind as to briefly check my proof? I am supposed to prove the statement without using any theorems which would render the proof trivial.     If $\displaystyle\int_a^b f$ exists then $f$ has infinitely many points of continuity in $[a,b]$   For the sake of contradiction suppose $f$ has finitely many. It suffices to show that there is an interval $[u,v]\subset [a,b]$ over which $f$ is not Riemann integrable. Pick any $[u,b]\subset [a,b]$ such that $f$ is discontinuous everywhere in $[u,v]$. For any finite partition $D=\{x_1\cdots x_n\}$ of $[u,v]$ let:  $$s(f,D)=\sum_i (x_{i+1}-x_i)\inf_{x\in[x_{i},x_{i+1}]}f\quad\text{and}\quad S(f,D)=\sum_i (x_{i+1}-x_i)\sup_{x\in[x_{i},x_{i+1}]}f$$ We prove $\sup_D s(f,D) <\inf_D S(f,D)\;(1)$. To achieve this consider an arbitrary chain: $$D_0\subset D_1\subset \cdots$$ Pick any $I_0\subset I_1\subset \cdots$ where $I_k=[u_k,v_k]$ and $I_k$ is an interval of the partition $D_k$. Without loss of generality $\bigcap_i I_i=z$. Given that $f$ is discontinuous everywhere, there exists $\epsilon>0$ such that for any $\delta>0$ there exists $y$ such that $|z-y|<\delta$ yet $|f(z)-f(y)|\geq \epsilon$.   This immediately implies $\displaystyle\sup_{I_n} f>\inf_{I_n} f$ and hence $\displaystyle\sup_{D_n} s(f,D)<\inf_{D_n} S(f,D)$.   This is valid for any sequence $D_n$ so claim $(1)$ holds, contradicting the integrability of $f$.


How to block google analytics spam from hulfingtonpost.com?

Lately my Google Analytics is getting bombared with fake searches, referrals from ilovevitalli.com, resellerclub.com, hulfingtonpost.com and apple.com.   One of my sites shows search results like these in it's analytics widget:    How can I block these fake referrals and searches once and for all? I have set filters in Google Analytics but they keep showing up.


Why double equal to in Strings work so differently?

String str = "hello";     String s = str;      System.out.println(str==s);      String str2 = new String ("world");     String s2 = str2;     System.out.println(str2 == s2);      String str3 = str + str2;     String str4 = "helloworld";     String str5 = new String ("helloworld");     System.out.println(str3 ==str4);      System.out.println(str3 ==str5);  Output true true false false Can anyone explain to me the output of the above program snippet in Java?


Web design company backlinking technique

I own a small web design company and most of our backlinks come from having a link on our client sites, I am just wondering what is the best method of including a link on each clients website.  Currently we tend to use:  Web Design by Company Name  and link on the company name. Occasionally we mix this up a little by doing something like:  Property Website by Company Name  and link on the whole sentence. We always do sitewide links at the moment.  Is this a good method? Should we only be linking on one page maybe? (homepage?) any thoughts are much appreciated.  Edit: I know similar has been asked before in this thread:  but as SEO has changed a lot in the last year I think it's valid to ask this again.


Making "Figure 1" bold breaks references to it

I have a figure with a caption. Normally, the caption shows up as Figure 1 MyCaption. However, I want the "Figure 1" part to be in bold. I found the answer to this on this website; the fix is to use \usepackage[labelfont=bf,textfont=md]{caption}. However, references to the figure do not work anymore. Is there any way to fix this? Thanks.  MWE  \documentclass{book} \usepackage{graphicx}   \begin{document}  \section{First Section} The picture is shown in Figure \ref{pic}.  \begin{figure} \label{pic}     \caption{The Picture} \end{figure}  \end{document}


I have an object that can build itself from an XML string, and write itself out to an XML string. I'd like to write a unit test to test round tripping through XML, but I'm having trouble comparing the two XML versions. Whitespace and attribute order seem to be the issues. Any suggestions for how to do this? This is in Python, and I'm using ElementTree (not that that really matters here since I'm just dealing with XML in strings at this level).


Why does adding independent variables make all independent variables insignificant?

I am running a logistic regression in Stata to try to determine which independent variables potentially cause a response in a binary dependent variable.  When I run certain independent variables against the dependent variable I get very high significances around $p=.005$. However, when I add all of my variables together into one logistic regression equation all of the significances spike to $.1$ or higher, and many go from $.05$ to $.5$ or higher. It seems that the more variables added, the lower the significance goes, even if the variables are all significant by themselves against the dependent binary variable.


PDO secure ways to safe code from sql injections but using kali can still cause to inject

I have google and searched for sanitization the user posted data and found lot of examples and functions but i haven't find yet any solution which help me to resolve my confusion.   My question is that what is basically done in the following php mysqli built-in function:    // Sanitize. example:   $x = mysqli_real_escape_string($con, $posted_val));   is there any built-in function in PDO or in core php to sanitize the user posted data with?  I have tried to use my own function to sanitize the input by replacing the possible exploitable code and then return the result but I hope there may be some built-in function exits in PDO too? or I may be wrong...


Given $A, I+AB\:$ invertible matrices, prove that $I+BA$ is invertible and that $$(I+AB)^{-1}A = A(I+BA)^{-1}.$$ How should I approach this? The question seems similar to  but I can't make the connection


my figures in latex must have caption like this: FIGURE 1. figure name which command gives me this capital figure name?   \documentclass[11pt,a4paper]{article} \usepackage{graphicx} \usepackage{caption}     \begin{figure} \centering \caption{figure name} \end{figure}   I need to have FIGURE1.figure name instead of FIGURE 1: figure name how can i fix this?


Prove that If gcd$(a,2)=1,$ and $p$ is an odd prime, then $(a^{p-1})-1$ is divisible by $8$.


Is there a subtle difference between "inherent" and "intrinsic"?

I've always used "inherent" and "intrinsic" interchangeably. Dictionary.com doesn't offer much help in distinguishing them.


Ubuntu 18.04 change startup service order

My problem is ics-dhcpserver starts before network services so dhcp cannot find interface i can swap/change order for startup services?  Regards, Aki


Video Editing - video strips go black after adding images

I had a few .mov video files in channel 1, and it rendered fine, but then I tried to add an mp4, and I got an error (xyz.mp4 could not be loaded), so I decided to add some .jpg images instead.  The images rendered fine, but when they weren't on screen, it would render as black. Even when I removed the images, it would render as black.  I tried duplicating one of the strips from the first channel and putting it into the second channel (hoping is was just an issue with the channels), and it still had that issue.  But when I added a new .mov, it would render that one fine, but it wouldn't fix the other strips.


How to find all integer pairs $(x,y)$ that satisfy the equation $21x+47y=1$ without using modular arithmetic?

Find all integer pairs $(x,y)$ that satisfy the following equation:   $$ 21x+47y=1. $$   I know the solution with modular arithmetic:  \begin{align} 0x + 5y &= 1 \pmod{21} \\    5y   &= -20 \pmod{21}\\  y = -4 \pmod{21} &\Longleftrightarrow y = -4 + 21c \\ 21x + 47(-4 + 21c) &= 1\\  21x &= 189 - 21 * 47c \\   x &= 9 - 47c. \\ \end{align}  Therefore  $$(x, y) = (9 - 47c, -4 + 21c)$$   Is there a way to do this without modular arithmetic? Thanks in advance!


Where does the energy go when I short a capacitor?

Please, help me find the mistake in this line of thought, or solve the inevitable question at the end. 🙂   suppose there are two facing plates with different charge $Q_1$ and $Q_2$ these two plates are the only thing in the universe because of the charge imbalance, there is electrical energy in the system now I connect the two plates with an ideal conductor of zero resistance the excess charge in one plate goes to the other plate, without dissipating heat at the end there is no more charge imbalance, no more electric energy in the system where did the energy go?


MicroSD card write protected, cannot unlock (tried on different computers, different adapters)

I am on read only on my microSD card, that previously I was able to read/write on. I've tried using different adapters, tried locking then unlocking those adapters (as well as putting the toggle in the middle), I've also tried reading the card on different computers, to no success. I've also tried to "overwrite" on the SDFormatter app (that I previously used when I was able to edit the card), but the SDFormatter also says that they cannot make changes unless the write protection is off. Any suggestions on how to fix this?


How to use downloaded fonts with pdfLaTeX on Ubuntu

I want to use the  font in my pdfLatex document.  What steps should I do for using a downloaded font   Should I download the TTF or the OpenType version? Where should I store the font? Should any font processing be done? How can pdfLatex find this font?   I am using TexLive 2011 installed in a custom location (/somepath/texlive/2011) on Ubuntu


Why can't I find a USB-C hub with multiple USB-C ports?

My computer only has one USB-C port and I want to connect multiple USB-C devices to it.  I have trawled through Amazon but am amazed that I cannot find a single one. There are many hubs that have USB 3.1 USB-A ports but not USB-C ones.  Is there a limitation in the spec that prevents this being possible?


Why does wget return a HTTP 403 error to download openSSH pet?

I am trying to learn how I would get OpenSSH using the command line. I found a *.pet link on this webpage:  which says:  Installation Install an appropriate software package: openssh-5.2p1.pet at qcjn.no-ip.org:81/pupstuff openssh-5.1p1 client and server package thread packaged by Sven  I assumed I could use wget to retrieve the *.pet file. So I tried: sh-4.1# wget -o log -v qcjn.no-ip.org:81/pupstuff/openssh-5.2p1.pet    Nothing appeared on screen, but the log file said: --2014-06-29 18:01:33--  http://qcjn.no-ip.org:81/pupstuff/openssh-5.2p1.pet Resolving qcjn.no-ip.org... 173.176.253.77 Connecting to qcjn.no-ip.org|173.176.253.77|:81... connected. HTTP request sent, awaiting response... 403 Forbidden 2014-06-29 18:01:33 ERROR 403: Forbidden.  Why was I denied access? I was able to download and install the files using a web browser and ppm:  But I really want to learn the command line.


Power Supply 4.2VDC broken. Freedom of choosing new one

I've got a broken power supply for charging a lithium-ion battery with the following specifications: INPUT: 220-240VAC~50Hz MAX 11W OUTPUT: 4.2VDC 1200mA  As I'd like a new power supply and I don't find one on, e.g. amazon, my question is in what way do I have freedom in specifications of a new power supply?  What I found so far are specifications of switching power supplies like this:  INPUT: 100-240 Volt AC, 50/60 Hertz OUTPUT: 3 / 4,5 / 5 / 6 / 7,5 / 9 / 12 VDC - 600 mA  INPUT: 110V-240V AC OUTPUT: 3V / 4,5V / 5V / 6V / 7,5V / 9V / 12VDC 600mA at 3V-6V / 450mA at 7,5V / 400mA at 9V / 300mA at 12V  INPUT: 100-240 V AC OUTPUT: 3-12 V DC (3,0/4,5/5,0/6,0/7,5/9,0/12,0 V) 1000mA  INPUT: 100 ~ 240V 50/60HZ, max. 500mA OUTPUT: 5V/2,4A; 6V/2A; 7,5V/2A; 9V/2A; 10V/2A; 12V/1,5A; 15V/1,5A   Is one of these four power supplies eligible as a replacement?


What is the simplest way to bend a plain rod (subdivided cylinder) and give it a U-shape (for instance) ?  Here is a solution: As suggested by cegaton best option is using Warp (not Bend) with cursor on symmetry axis (distance gives radius) and 90° offset. Straight plain rod is changed to round rod with no deformation.


Are OEM's retaining Synaptics driver for linux?

On their website, Synaptics states that they delivers their linux driver to OEM when they buy Synaptics product :     SGS-L is provided free of charge to Synaptics OEM/ODM partners when ordered with Synaptics TouchPad and ClickPad™ products.     It's advertised as the same as the windows driver. So should I call Lenovo/HP/Dell to get my fully working touchpad driver in linux ?


How to call appropriate module in Python?

#!/usr/bin/python  Import time Import Script1 Import Script2 Import Script3  Options = {'Script1.py', 'Script2.py', 'Script3.py'} no_of_options = 3  choice = int( time.time() ) %no_of_options  if choice == 0:              python (Script1.py)  if choice ==1:             python (Script2.py)  if choice == 2:             python (Script3.py)   I want to randomize the script chosen. But I've noticed that the first script is always executed no matter what. Also, if I write 'import Script2.py' first, then Script2 gets executed first no matter what. Please help me fix this.  Please offer some help. I have written three modules as separate .py files and a different one needs to be executed randomly. Tell me how to execute a different module each time depending on the value of choice.   Edit : Here is what I want to do. There are three different patterns available. I have written a separate Python program to print each of these patterns. One of these three patterns must randomly be executed. What I have tried to do is get a random number and then accordingly execute one of these three scripts to display the corresponding pattern.  Please correct the syntax or suggest a better way to do this.


Call a javascript function after 5 sec of last key press

I have a form with an <input type=text /> and I want to call a javascript function after 5 seconds of the last key press, and every time a new key is pressed, this timer should reset and only call the function after 5 seconds.  How can I do this?  I'm using jQuery.  thanks!


Is there a Settings/System Preferences simulator for macOS/iOS tech support?

Frequently when offering technical assistance, I either want to follow along with my own instructions to make sure they are correct, or provide a screenshot to demonstrate my instructions visually. Often, it is sufficient to do so on my own device, but there are a number of problems that can come up with this method:   If my device is running a different version of the operating system, what I see is likely different from what the user sees. If it is an area of Settings that shows sensitive information, I need to either use a Guest account without personal information or censor it later. The former is not possible on iOS without buying a dedicated device for it, and censoring images takes time. Getting a screenshot from an iOS device to my computer is fairly simple, but the time adds up when compared to doing the same on macOS. If there are device-specific settings, and I don't have a device with those capabilities (for example, none of my devices support Force/3D Touch), I won't be able to help.   Using Xcode's iOS Simulator is almost never a viable alternative, as its Settings app is greatly pared down and only includes a handful of options.  Does there exist some Mac app whose purpose is to simulate the Settings or System Preferences app of various devices and OS versions?


When should I use "to have a dinner" instead of "to have dinner"?

As said in  commentary, to have a dinner isn't ungrammatical, but implies a dinner for a specific reason. Examples are:   we're having a dinner in his honour  we're having a birthday dinner for you   but the difference is totally unclear for me. What is changed, if I'd say we're having dinner in his honour, for example.


My friend and I decided to meet between 1 and 3 PM today. There is a condition that whoever arrives first will not wait for the other for more than 20 minutes. what is the probability that we'll meet today?


How we fix (La)TeX math coding to be left aligned

In display math (employing $$...$$) content normally gets aligned centered. But, I need it to be left aligned. Any suggestions?  Example  $$f(x) = \frac{{{{\sin }^2}x{\mkern 1mu} \cos x}}{{\sin x + \cos x}} -          \frac{1}{4}\tan (\frac{\pi }{4} - x){\mkern 1mu} {\mkern 1mu}           \forall {\mkern 1mu} x \in R - \{ n\pi  - \frac{\pi }{4}\} ,n \in I$$


Why do we need Merkle–Damgård strengthening

Reading through some manuals, wikis and other documentation I'm learning about Merkle–Damgård construction. I understand why padding beginning with '1', followed by '0's is needed, but I can't understand why we're adding length of input in the end. This length-padding is called Merkle–Damgård strengthening. Could anyone explain to me why it's needed. I don't see the benefit.


structure of sharepoint javascript functions

I am trying to understand more the structure of javascript functions in SharePoint. Why does every function begin with som value than colon and semicolon like ULSrE8:; in spgridview.debug.js:  function ULSrE8(){   var o=new Object;   o.ULSTeamName="Microsoft SharePoint Foundation";   o.ULSFileName="spgridview.debug.js";   return o; } var SPGridView_CallbackContext=null; function SPGridView_FilterPreMenuOpen(gridViewClientId,                                       templateClientId,                                       menuClientId,                                       dataFieldName, e) {ULSrE8:;     var gridView=document.getElementById(gridViewClientId); ...   What does {ULSrE8:; do?


How do I compare a message in chat to another pre-made message?

You might be a bit concerned about this question, well, I'll explain it! I want a command block to be searching for anyone saying .clearchat and if it comes out true it will clear chat. Is it really possible(?), and if it is leave an answer below!


Will Aragorn's and Arwen's Kids be immortal?

Aragorn is a Dunedain and Arwen is an Elf who has the power of immortality. Will their kids have the power of immortality ?


The Times is a highly (respected or respectable) journal?

What is the correct usage?     The Times is a highly (respected or respectable) journal.   And if we changed the sentence to this, would you change your choice?     The Times is a highly (respected or respectable) journal all over the country.


Why do very small balls attached to a tiny spring propel themselves in hardly moving fluids?

I recall watching a youtube video about a ball with a spring on the idea propelling themselves through stable fluids without any assistance, even if we make sure the spring isn't moving in the beginning. It'd be a great help to get an explanation as to why this happens since I haven't been able to find the video after searching for quite a long time. Since soap molecules also share the same shape as a ball and a spring, it may be possible that soap molecules could propel themselves as well.


Installing Minecraft mods without a bin folder or minecraft.jar

I have been playing Minecraft for a while, but I recently decided to try mods.   I managed to bypass the bin folder, since everything I needed could apparently be found in the versions folder.  I am being told that I need a minecarft.jar folder, which isn't in 'versions', and I have no bin folder either.   I enabled "show hidden files", but nothing showed up.    I am trying to install Tinker's Construct. Am I doing something wrong


xdotool not working after Ubuntu 17.10 upgrade

This is my first day after upgrading from 17.04 to 17.10. I've noticed that xdotool is not working as it used to. For example:  xdotool type "Lorem ipsum" types nothing.   xdotool key ctrl+shift+t doesn't open a new tab in gnome-terminal.  xdotool mousemove 0 0 doesn't move the mouse.  xdotool click 1 doesn't click on the stuff under the mouse.  xdotool getactivewindow windowmove 100 100 doesn't move the active window and returns an error:   XGetWindowProperty[_NET_ACTIVE_WINDOW] failed (code=1) xdo_get_active_window reported an error   What I found is still working:   xdotool search --classname Navigator windowactivate does activate the browser.  xdotool getmouselocation --shell returns info about mouse position.  xdotool selectwindow does allow me to click on a window to get its id.  I have some scripts that rely on this tool. Any suggestion how to fix this?  UPDATE: I'm using Wayland display manager. Switching to Xorg makes it work again. Is it possible to make xdotool work again while still using Wayland?


$\xi =e^{2*\pi/pi }$ , proof that is only two quadratic extention to $\Bbb Q $ that contained in $Q(\xi_p)$

$\xi_p =e^{2\pi/p*i }$ , proof that is only two quadratic extention to $\Bbb Q $ that contained in $Q(\xi_p)$ such that $\Bbb Q(\sqrt p)$ if $p=1 mod (4)$ or   $\Bbb Q(\sqrt{-p})$ when $p=3mod(4)$  In the class we proof that $p*(-1/p)=z^2 $ when $z=\sum_{a\in \Bbb F^x_p}(a/p)*\xi_p^a$  when  (-1/p) = 1 if p=1 mod 4             and  =-1   if p=3 mod 4  so it`s how I proof the statment. but how to show that this is the only two that possible according to the statment? I try by contradiction for $z\in \Bbb Q $ such that $\sqrt z \not= \sqrt p $  so $\sum_{i=1}^N a_i*\xi_p^i=\sqrt z$  for some $a_i\in \Bbb Q $ but Its lead me to nowhere...


When is it appropriate to use the original pronunciation of a foreign word versus the English pronunciation?

When reading to an audience, or speaking in conversation, when is it appropriate to use the original pronunciation of a foreign word versus the English pronunciation (assuming you know the appropriate pronunciation for it)? Is it considered rude, or condescending? Or is it considered a mark of being knowledgeable?  One of the things to consider are place names. When referring to Paris, France, should it be pronounced with the silent 'S' as the French would say it, or with the 'S'? Should Hiroshima be pronounced as a Japanese speaker would pronounce it slightly more emphasis on RO, rather than the SHI? Should Mount Pinatubo be pronounced as a Filipino speaker would pronounce it with shorter stronger vowels, or the longer vowels? (e.g. Pi as is 'pick' rather than 'pea'.) Should Wichita be pronounces as the original "shi" rather than the modern "chi"?  Pronounce pesos or sombrero as a Spanish speaker 'eh' or the English 'ay'?  (I can't think of other common words right now that aren't words taken from other languages like hurricane, boondocks, tornado, etc. which I think have (correctly) changed to English pronunciations.)


Unable to set Google Chrome as default browser in Ubuntu 12.10

despite several attempts at making Google Chrome work as my default browser I simply cannot.  I've read countless threads on the internet, checked mimeapps.list and so on, tried about anything, from simple system configuration by going to settings and change as the default browser there, which, for some odd reason, won't allow me to set a default browser, to more advanced terminal scripting.  This is a clean install of Ubuntu 12.10 x64 bit updated to the latest version including kernels.


I've turned on the , and now notice that my Contacts button has disappeared. It used to be above Compose. Does anyone know where it has gone to?


What should be used in this sentence:  Who else is feeling hot (besides/ beside) me?


How to do integer & float calculations, in bash or other languages/frameworks?

Using echo "20+5" literally produces the text "20+5".  What command can I use to get the numeric sum, 25 in this case?  Also, what's the easiest way to do it just using bash for floating point? For example, echo $((3224/3807.0)) prints 0 :(.  I am looking for answers using either the basic command shell ('command line') itself or through using languages that are available from the command line.


Sorry I am new to ubuntu, just installed it.  The version Ubuntu 14.04.4 LTS.  I finally learned how to install a program called WebStorm and trying to create an alias for it.  I tried creating it under ~/.bashrc and ~/.bash_aliases and ~/.bash_profile by reading all the other forums here but none of them worked.  I tried adding alias such as:  alias ll = 'ls -l'   as a test I tried adding them in /.bashrc and /.bash_aliases but each time when I open up my terminal it'll give me an error saying ll is not a command or something but finally adding into /.bash_profile wouldn't give me such error messages.   What I wanted to add as alias is a something like this:  alias ws = '~/Apps/Webstorm/bin/webstorm.sh   but when I run ws in terminal it says:     ws: command not found   but if I just run:  ~/Apps/Webstorm/bin/webstorm.sh   directly it'll run the program.   What am I doing wrong here?


How do I get from a beta site to its Area 51 page?

It's easy to click "Visit the site now!" on the Area 51 page, but how can I go back without using the search engine on Area 51 or using the back button on my browser?


Low graphics error unless I boot via recovery mode

I recently upgraded to 12.10 (fresh install). I am a facing weird problem:  When I boot, I get a message notifying me of low graphics. For now, I have been switching to console using Alt+F1 and then rebooting.  Upon reboot, I select recovery mode, allow system to boot and then again reboot.  Now I select normal mode and my graphics load smoothly.  Could you please tell me what could be the issue? I have a Dell Inspiron 5230 with Intel 4000 onboard graphics.


$\{x^k\}^\infty_{k=0}$ is not basis in $C[0;1]$.  I know how to show that a system of functions is basis if it is orthogonal (Parseval's identity), but I do not understand how to show it for arbitrary system.  Possibly, we should find a continuous function that has some problems with approximation with an infinite sum of monomials, but I have no idea what contradiction we need to obtain.


What is the difference in meaning between these two sentences?     I asked where she kept her jewellery, but she didn't tell me where.      I asked where she kept her jewellery, but she wouldn't tell me where.


Where did "nightingale" get its second N from?

I noticed while searching the etymology of the word nightingale that it did not have the second N. The sources I checked only say intrusive N but don't explain it. :  From Middle English nyghtyngale, nightingale, niȝtingale, alteration (with intrusive n) of nyghtgale, nightegale, from Old English nihtegala, nihtegale    Middle English nighte-gale, from Old English næctigalæ, in late Old English nihtegale, a compound formed in Proto-Germanic (compare Dutch nachtegaal, German Nachtigall) from *nakht- "night" (see night) + *galon "to sing," related to Old English giellan "to yell" (from PIE root *ghel- (1) "to call").  As you can see, in Old English and Middle English, it did not have the second N so the present day N is not original. Etymology Dictionary also says "With parasitic -n- that began to appear mid-13c." but doesn't explain the reason English people put it in "Nightegale". Can anyone explain the reason?


"command not found" when running a shell script. What did I break?

I'm on OSX Snow Leopard.  Here's the full contents of grr.sh:  #!/bin/sh  echo wow   When I try to run it from terminal:  $ grr.sh -bash: grr.sh: command not found $ /bin/sh grr.sh wow $ sh grr.sh wow $ bash grr.sh wow   Okay. Fair enough. I'll give it executable permission, then try again:  $ chmod +x grr.sh $ grr.sh -bash: grr.sh: command not found $ chmod 755 grr.sh $ grr.sh -bash: grr.sh: command not found   Hmmm. Maybe it'll work if I use bash explicitly? I'll change the file's contents to:  #!/bin/bash  echo wow   And I get the exact same results. What could I have broken?!  One last thing! In case you're curious...  $ which sh /bin/sh


Why can I change permissions for a file with 000 permissions?

I have the following file:  ------- 1 user user 0 may 26 14:07 a.tar.gz   When I execute chmod 777 a.tar.gz, the file permissions change.  Why does this happen, and how can I block it?


Looking at the Steam Community page on my inventory, I can see that any community item such as a profile background, trading cards or emoticon can be converted into a certain amount of gems.      However, I never entirely understood what defines this value. What I have noticed is that the more popular its respective game is, the more valuable the item will be in gems. But if that's the case, what defines that game as being popular? How many times it's been purchased, the amount of reviews? And what about any base values?  How are the gem values calculated?


Software centre (in 16.10) won't recognise my Ubuntu One password

I'm trying to install both VLC and Krita via the software centre and it's requiring me to create an Ubuntu One account, which I did; only trouble is though, is that the password I created isn't being recognized by my system! Does anyone know how to sort this?


How to prevent updating of a specific package?

Because of  I'd like to prevent apt-get upgrade and Update Manager from updating the "libgtk2.0-0" package.   How can this be achieved?


Finding Nth largest element in huge 2D array

I'm trying to find the N-th largest element in a large 2-D array( approximately 850,000  elements). The method I'm using now is converting it into a 1-D array and then using the selection sort algorithm and finding it that way but it takes way too long.   Does anybody know a good way to find the N-th largest element while just looking through the matrix without sorting it, like finding the largest element.


Let $S=\{1,2,3,4,5....,2070\}$ and $A$ be the number of subsets of $S$ whose sum of elements in $S$ is divisible by $9$.If $$A=\frac{2^a\left(2^b+1\right)}{c}$$then find the values of $a,b$ and $c$.  The given solution is quite cryptic:  Let $f(x)=(1+x)(1+x^2)(1+x^3)....(1+x^{2070})$.  Then $A$ must be the sum of coefficient of $x^{9k}$ where $k$ is non-negative integer.So, $$A=\frac{2^{2070}+8.2^{230}}{9}$$How has the author of this question calculated this expression


I'm writing a report, and have a rather large table in my appendix. I'd like to emphasize some specific values by coloring some single cells. I'm trying to do it with xcolor. But receiving the error:  ! LaTeX Error: Option clash for package xcolor. See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.17 The package xcolor has already been loaded with options: [] There has now been an attempt to load it with options [table]   My preamble looks as follows  \documentclass[a4paper,oneside,article]{memoir} \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc} \usepackage[danish]{babel} \usepackage{lmodern} \usepackage{graphicx}     \graphicspath{{Figures/}} \usepackage{fullpage} \usepackage{modroman} \usepackage{float} \usepackage{caption} \usepackage[numbers]{natbib} \usepackage{url} \usepackage{pgfplots} \usepackage{mathtools} \usepackage[table]{xcolor}   And take out of my table  \begin{table}  \centering   \begin{tabular}{|c|c|c|}        \hline    \cellcolor{green!25}D & x & D/$L_0$ \\        \hline    65 & 2600 & 0,417\\        \hline    60 & 2400 & 0,385\\   \end{tabular}  \caption{Bestemmelse af bølgehøjde}  \label{tab:Q1} \end{table}   Read some other questions asking more or less the same. And the answer to them seems to be a "collision" between packages. I have no idea how to find the problem. So my question is:   Where is the "collision"? How on earth would I have found it without help ?


Assign an Object with a String of its Property

Let's say I have a class called Student where it has properties of ID, FirstName, LastName. I have a dictionary which stores some information of a particular student.   I want to do something like   var student = new Student(); var studentInfo = new Dictionary<string, string>(); studentInfo["ID"] = "12345"; studentInfo["FirstName"] = "John"; studentInfo["LastName"] = "Doe";   Now I want to assign the key to the attribute of the student. Since the keys of the dictionary are the attribute of the student. I want to assign the Value of the dictionary to the student depending on the key. Here's my pseudo code.   foreach (var studentInfoItem in studentInfo) {     student.studentInfoItem.Key = studentInfoItem.Value; }   Is there any way to do this properly?


What's the difference between these two commands?  cat /proc/uptime | awk '{print $1}'  < /proc/uptime awk '{print $1}'  Specifically, how does the second command work? Doesn't the redirection operator < has to be accompanied by a command? What does it mean to redirect the contents of a file like that?


How to write text in style LaTeX is written?

I want to write text not in English but some other font and language  in same manner as \LaTeX writes. i.e. some characters are raised some low, with kerning and all that. I am using XeTeX since I have to work with other language.


Is 1 hour and 30 minutes enough time to catch connecting flight in Istanbul Atatürk Airport, Turkey?

I am traveling from New York City to Skopje and I found cheaper tickets with Turkish Airlines from NYC to Istanbul then I'll have 1 hour and 30 minutes to catch my connecting flight to Skopje.   Is this enough time to get through all the security checkpoints at that airport since all of the attacks have increased security?


How to find the triangles resulting from clipping a triangle against a convex polygon.

We have a 2D triangle. It has 3 points. We have a 2D convex polygon. It has N points. Normally when clipping, one wants to produce the polygon or list of triangles inside the convex polygon. I want to do the opposite. I want to get the list of triangles that do not intersect aside from bordering edges, and are NOT within the convex polygon and result from clipping. For example if I had a triangle with a square completely enclosed within, I would want to get the list of triangles representing the triangle with a square missing from the center.


Can I see which seats are available on a British Airways flight before I book?

Some airlines (for example, ) offer a seat availability checker so you can see which seats are currently booked on a flight - there are limitations, since some seats might show as occupied but are actually reserved for priority customers - but it's still useful.  Is there any way of getting this kind of live seat booking data for British Airways before you have booked a flight? This would help me select which of several flights I might pick (for example, where I might be able to select a better seat, or where the plane is lightly loaded).


Benefits of using backtick (`) in MySQL queries?

In MySQL we can create queries with or without the backtick (`) symbol. Example:   SELECT * FROM TEST; SELECT * FROM `TEST`;   Both works fine in mysql-console.  Is there any technical difference between them?  Is there any benefit using (`) over over simple queries?


If I wanted to reinstall my Windows 7 Pro OEM, what would happen on activation?

My sister's old work laptop is finally showing signs of aging, and she wants to reformat it to start over.  It's running a Windows 7 Pro (OEM) that she bought herself, as the laptop previously only came with a trial version of Home.  So, my question is, what would happen on activation? Would Windows 7 have installed the key onto her motherboard and she doesn't need to re-enter the key?  Or if she does need to re-enter the key, what would happen? Would it just work? Do we need some activation procedure?  We can't really do the phone activation as a.) We don't have a phone b.) We're in the Philippines


I was wondering, if I use an old home machine as a server - how many connections will I be actually able to support. I was able to calculate the connection's capabilities myself as it is quite simple.  30 mbit/s = 3.75 MB/s, with average request size of 150 KB 3750/150 = 25. So theoretically my connection will support 25 requests per second on average.  I am not sure how to do that for the hardware, though. The result will probably be greater than 25 which makes it irrelevant to the situation but I am doing it to learn. As well as there is always the possibility to upgrade my connection.  This is the hardware:  Motherboard  SMBIOS 2.5 present.  Handle 0x0002, DMI type 2, 15 bytes Base Board Information         Manufacturer: BIOSTAR Group         Product Name: G31D-M7         Version:         Serial Number: None         Asset Tag: To Be Filled By O.E.M.         Features:                 Board is a hosting board                 Board is replaceable         Location In Chassis: To Be Filled By O.E.M.         Chassis Handle: 0x0003         Type: Motherboard         Contained Object Handles: 0   Processor     Intel(R) Core(TM)2 Duo CPU     E7500  @ 2.93GHz    Memory  /0/0                        memory      64KiB BIOS /0/4/5                      memory      64KiB L1 cache /0/4/6                      memory      3MiB L2 cache /0/f                        memory      4GiB System Memory /0/f/0                      memory      2GiB DIMM SDRAM Synchronous /0/f/1                      memory      DIMM [empty] /0/f/2                      memory      2GiB DIMM SDRAM Synchronous /0/f/3                      memory      DIMM [empty]   Usage               total       used       free     shared    buffers     cached Mem:          3943        966       2977         77        109        556 -/+ buffers/cache:        299       3644 Swap:            0          0          0   My application executes in 0.023s and uses 225KB of memory on average of 1000 requests.  If any more information is needed I will provide.


$\operatorname{ord}(u)=r,\,\operatorname{ord}(v)=s$ $\,\Rightarrow\,\operatorname{ord}(uv)=rs\,$ if $\,r,s\,$ (co)primes

Let u and v be elements of a commutative group, and suppose that their   orders are r and s, respectively. Show that if r and s are distinct   primes then the order of uv is rs.   I will use the follwing theorem to proof this.  Theorem: Let x be an element of order m in a finite group G. Then $$x^s=1$$ in G if and only if s i a multiple of m.    My attempt  We can here see that $$(uv)^{rs}=[commutative]=u^{rs}v^{rs}=1^s1^r=1$$ By the theorem, this tells us that this is true only if only rs is a multiple of the order of $uv$. Let the order be $ord(uv)=k$. We know that every positive integer can be written as $$a=bm+l, 0<=l<b$$ and since $r$ and $s$ is primes (positive integers), $rs$ can be written as $$rs=km+l, 0<=l<k$$ This gives ut that $$1=(uv)^{rs}=(uv)^{km+l}=1^muv^l=(uv)^l$$ If l>0 then the equation $(uv)^l=1$ contradicts that the positive integer k is the least positive integer for which $(uv)^k=1$. Therefore l=0 and $rs=km$ . We can here see that $rs$ is a multiple of k (and this proof also the theorem).  $$rs=km => k | rs => k|r     ORk|s$$ But we know that $r$ and $s$ are distinct primes, so k must be equal to one of the primes.  $$k=r => (uv)^k=(uv)^r=1v^r=v^r=1$$ And since we know that $ord(v)=s$ the theorem tells us that $r$ must be a multiple of $s$. But since both of them is primes, we get that $r=s$ but this is a contradiction (r and s are distincts as the exercise tells us).   Now, we try with $k=s$. Same as above, we get that $s=r$ which is a contradiction. Neither k=r nor k=s is right since by the theorem we get that $k=r=s$ and we have that $r$ and $s$ are distincts. This tells us that k cannot be equal to r nor s, since this gives us that $r=s$. And since we know (and as i did proof)that  $$rs=km$$, this tells us, as i wrote before, that $$k|rs$$ Since k is neither equal to $r$ or $s$, this tells us that k must be equal to $rs$. Therefore $$ord(uv)=k=rs$$.  Edit: i know that this can be prooved by l.c.m(x,y) but we have not used it so far. That's why i did not proof it with l.c.m(x,y)


My MacBook's Touch Bar went black, any solutions? Fingerprint works fine

How can I fix a Macbook Pro when the Touch Bar doesn't work? I have 13 inch 2019 MacBook Pro, and after updating to macOs 10.15.6, the Touch Bar went black. I visit keyboard preferences and saw this  no option for control strip I tried almost all methods even I erased everything and reinstall the macOS; now I am at Mojaive 10.14.6 METHODS I TRIED i. commands in terminal    sudo pkill TouchBarServer;       sudo killall “ControlStrip”;  But after second command an error shows up      No matching processes were found  ii. Erase everything and reInstall macOS from recovery mode Still the entire TOUCHBAR is black


How does Rita Vrataski find out that she lost her power to "reset" her day without killing herself?

In "Edge of Tomorrow", Rita Vrataski (aka "Full Metal Bitch", "The Angel of Verdun") narrates how, after the Battle of Verdun, she lost large amounts of blood. After a blood transfusion she lost her power to "reset" her day, which only happens when she dies.  How did she find out that she had lost her power? How did she find out for sure without killing herself?


How can I split a column data in sql. If hyphen is present, Only display the data before the hpyhen.


Applying parseInt on array yields weird result

Trying to run a simple javascript to parse single digit ints in a string as follows:  var s = "22123222222213123212322123213222"; var a = s.split(""); var b = a.map(parseInt); console.log(b); [2, NaN, 1, 2, 3, 2, 2, 2, 2, 2, 2, 2, 1, 3, 1, 2, 3, 2, 1, 2, 3, 2, 2, 1, 2, 3, 2, 1, 3, 2, 2, 2]   Why is there a NaN for element with index 1?  Fiddle in the console here:   EDIT  After getting the correct answer below I felt I had to lookup this "map(Number)" business. Turns out Mozilla has a "gotcha" clause concerning this specific case.


I'm working on a neural network with one hidden layer. So far I've implemented the algorithm, and I've been able to numerically verify the partial derivatives I get from back propagation. My problem is when I try to train the network by updating the weights. No matter what I do it doesn't seem like I can get my estimates to come close to the actual values.  The data I'm using is from the function:  $$ f(x) = \frac{\sin(x)}{x} $$  On a side note, I haven't added bias parameters because I couldn't get the dimensions to fit in back propagation once I added the bias in forward prop. Not sure if this is an issue since I understood the bias parameters as a safeguard against inputs equal to 0?  theta <- function(a){   a / (1+abs(a))      # Here we apply the alternative sigmoid function as our                       # non-linearity. } theta.prime <- function(a){   1 / (1+abs(a))^2 }  x <- c( 5.949110, -1.036600,  3.256780,  7.824520, -3.606010,  3.115640, -7.786960,         -7.598090,  2.083880,  3.983000,  8.060120,  7.879760, -2.456670,          -2.152720,  3.471950,  3.567960, -4.232630,  6.831610, -9.486860,  8.692330,         -1.551860,  0.917305,  4.669480, -7.760430,  2.835410) y <- c(-0.10804400,  0.78264000, -0.05313330,  0.13484700, -0.05522470, -0.05758530,          0.19566100,  0.13846000,  0.43534100, -0.16861400,  0.10625000,           0.08427310,  0.27012900,  0.44004800, -0.00880575, -0.10711400, -0.18671100,          0.01158470,  0.02767190,  0.06319830,  0.61802000,  0.87124300,          -0.25668100,  0.06160800, 0.10575700)   neuralnet <- function(x,y,theta,theta.prime,neurons){  w1 <- t(matrix(rnorm(neurons,0,.01),neurons,1))  w2 <- matrix(rnorm(neurons,0,.01),neurons,1) E <- 1 i <- 0   for(i in 1:1000){   ### Forwardpropagation ###   s2 <- x%*%w1   a2 <- apply(s2,c(1,2),theta)   s3 <- a2%*%w2   yhat <- apply(s3,c(1,2),theta)   ### Error function ###   E <- sum((yhat-y)^2)/length(x)    ### Back Propagation ###   delta3 <- (2*(yhat-y)) * apply(s3,c(1,2),theta.prime)   djdw2 <- t(a2) %*% delta3   delta2 <- delta3 %*% t(w2) * apply(s2,c(1,2),theta.prime)   djdw1 <- t(x)%*%delta2    ### Update the weights ###   w1 <- w1 - 0.01*djdw1   w2 <- w2 - -0.01*djdw2   i <- i+1   } print(i) print(E) return(yhat) }  yhat <- neuralnet(x,y,theta,theta.prime,2)


Calculating Confidence Intervals when proportion is skewed

I have 15,000 address strings which I have written a piece of code which assigns them to broad geographic region e.g. American address assigned to North America. I would like to check the accuracy of my code. However I must manually check the strings. To do this I've taken a sample (SRS). I set a margin of error of 5%, a CI of 95% and a response distribution of 50%. Therefore, I assumed that I would assign the correct region half the time.  The issue here is that I am much more accurate then I anticipated. Of my sample of 375,372 (99%) were assigned to the correct location. This means I am unable to calculate lower and upper confidence limits.  Is there any other types of formula I could use when your response distribution is skewed to a highly positive outcome? Or is the only remedy to simply increase my sample size?


Web api set Generic Class dynamically according the url

In the below code how to set generic 'T' as a class dynamically?  Currently am redirecting all the API request to a single web api called "dummy" by routing.  So url's like  "api/person" then take person as class  "api/students" then take students as class   So here how to pass person or students or any other dynamic  class in GenericDataController T.       //web api controller        public class dummyController :GenericDataController<T>       {         //      }   GenericData web api      public class GenericDataController<T> :ApiController where T : class     {      private IGenericDataService _dataService;     public GenericDataController(IGenericDataService dataService)     {         _dataService = dataService;     }      // GET: api/GenericData     public IEnumerable<T> Get()     {          return _dataService.Get<T>();     }    }   In my model i have all class models    public class Person{    //    }   public class Student{    //    }


I am looking for a free tool for drawing diagrams (either for OS X or online). My goal is to keep for myself a clear trace of the organization of my project. Something like .  Any ideas?  Actually, I want to design a .


Is there an overview of Beamer's slide (page) geometry anywhere?

I find this classic figure of LaTeX's page geometry very helpful:     Source:   Now, I am fiddling with some beamer slides and I could really use such an overview of beamer's slide layout. Does it exist anywhere? I have not been able to find it...  For now, I need it to figure out how to get the height of a frame's body.


My headset gives louder sound on the right side. And I change the balance in Windows to hear equal. But I couldn't find where I can balance my audio.  I searched for it but couldn't find.  This is the volume control:  My OS is Xubuntu


How does second partial derivative test be interpreted?

I know that what the formula is used to determine a point whether it has maximum, minimum, or saddle points; but, i do not understand how it is formulated. $$ H = f_{xx}(x_0,y_0)f_{yy}(x_0, y_0) − f_{xy}(x_0, y_0)^2 $$ The $f_{xx}(x_0,y_0)$ and $f_{yy}(x_0,y_0)$ are used to determine the concavity in x and y direction respectively, but why it is multiplied by each other. I also do not understand why it is subtracted by $f_{xy}(x_0,y_0)^2$ and why it has a power of two?


what is the role of "static" keyword in java?

I frequently see static keyword with variables and with methods. Why we use static with main(String args[]) method in java ? Can anybody explain me the role of static in easy terms. So i can understand it better


Do teachers really need a PhD to teach? I guess the origin of this requirement was that people with PhD's were probably the only source of knowledge (unless someone is willing to go to a library, get professional help, and pour through volumes of books). However, knowledge is freely available nowadays along with organized and structured content on several topics.   On the other hand, most Professors with PhDs are trained well in doing research, but they have minimal to no training in teaching. The incentive structures for tenure processes also focuses a lot more on academic publications and grants, and no so much on professional development in teaching.   So, I ask again, wouldn't the students be better off having a teacher with only a MS degree but with training in pedagogical techniques, as opposed to someone with a PhD with neither training nor interest in pedagogy?


SQL Server service account Windows privileges and rights

My question is, if you create a new domain user account for each of the SQL Server processes, what permissions should be set for each account? Or does the SQL configuration manager actually take care of this, and I just had an unforeseen issue?  I quite often have to setup Microsoft SQL Server and wondered if anyone can provide advice on configuring the accounts the services should run as. IMO this has been vaguely documented by Microsoft, while they point you in the right direction I have never been able to find any concrete examples.  To summarize what I've seen so far:  For simple deployments\development environments it is OK to use the virtual account defaults the installer uses: e.g. NT SERVICE\MSSQLSERVER  Avoid using the SYSTEM account, this is not secure.  For production and in domain environments it's recommended to use either a Managed Service Account, or create a domain user account (not an admin) for each service. Allegedly if you use a domain account at installation time the installer will set any required permissions for you.  If changing the service account on an existing install from a virtual account to a domain account the recommendation is to use the SQL Server configuration manager to set the new service accounts. Allegedly this will set any required permissions for you.  I just tried changing the service account in an existing install to a domain account and it would give me a logon failure until I granted the account log on as service permission, which contradicts the part where the SQL Server configuration manager will set any required permissions. (Although I'm not sure if a GPO may have interfered with setting this local security policy)  Microsoft does provide a list of the permissions that the SQL Server Setup grants .  But it's not clear to me if that is something I should be doing manually for the user I create to run the service as, or whether using the SQL config manager should automatically set these permissions.  SQL Server 2014, Domain Controller is on Windows Server 2008 R2.


Time/date not auto recognising my location for time zone after using a VPN

Recently I was using a VPN (provided by Avast) to secure my connection whilst traveling.   Right now I am not using it as I am back in my office.   But using it seems to have caused an issue with the auto time clock on my computer (see attached screenshot) any ideas how to resolve this?


Why when changing the width property in figure causes some spaces between the title and the text?

This is the LaTex code:   \begin{figure}   \centering    \includegraphics[width=80mm]{PLA.pdf}   \caption{Some figure} \end{figure}   When I change the width to 80 it causes the problem but when I change the width to something like 55, there will be no problem.  The spaces are depicted in the picture:


How should I set up swap encryption on 18.04?

Things change over time. The latest question I found on this topic was from 2014 and appears to refer to 14.04. We are running 18.04 server. What is the current way to setup swap encryption? Is the preferred process still the same?  The requirements are, on boot clear swap, create a key and enable encryption of swap. On shutdown/reboot, forget key.  The documentation I am being pointed to is for desktop/laptops and is focused on hibernation and forces you to provide a password on boot and so is not a suitable option for servers.  In the comments below I have had suggested:   ecryptfs-setup-swap cryptsetup   If we add other currently unknown options to this list, which is the preferred method? I expect this server to last ~5 years. Is one better than another? How?


What if I offer bounty but got no answers per week

I want to ask, what happens with reputation in case if someone offers some reputation as a bounty for a question, but during bounty time there is zero answers (or given answers are deleted by moderators because they are useless).  Does reputation goes back to person who offered the bounty or it just vanishes?


Let $G$ be an abelian finite non trivial group and $p$ a prime number which devises o(G). We denote $H$ the set of non trivial subgroups of $G$. Could you please help me to show that if there exists $M\in H$ such that $p$ devises $o(M)$  then there exists $g\in G$ of order $p$. Thanks in advance


Why do we get a coloured spot on TV while dragging a bar magnet near the TV?

Why do we get a coloured spot on old crt TV while dragging a bar magnet near the TV?


Possible Duplicate:          In a table I would like to have a line break in the text inside a cell. Is there an easy way to do so, or do I have to create a new line without borders? The same holds true for other situations such as breaking a line in a caption for instance.


I've searched the manuals and plugins and done some tests..  Is it in any way possible to perform 3D drawing and editing of vector objects for 3D mapping e.g. in a 3D shapefile or PostGIS 3D table?


I'm learning about networking, at home I have two physical machines and a bunch of VMs that I use to test my applications each machine has a different hostname and I map them manually in each /etc/hosts files  I would like to know what's the difference between home IP adress (127.0.0.1) and a real IP address given by the network in /etc/hosts  for example   let's say my IP address is 192.168.2.20 and the name host is naruto and my /etc/hosts looks like this:  127.0.0.1       localhost 192.168.2.20    naruto 127.0.0.1       naruto   all lines point to the same machine I understand that the main difference is how programs connect to each of them two are using loopback device and the other one is using a nic. my question is should I have all these lines? or what lines should I have? what's the use of each of them?  I was reading this  but it didn't help, I got more confused


Add update notification bubble to admin menu item?

I have re-worded this to make more sense.  Ok, I have a plugin that uses a remote service that check for updates, much like default WordPress plugins, in this case it just checks an XML file.  I want to show a menu bubble like this  when an update is available.  It can show just a "1" or text like "alert", it doesn't matter.  Since my plugin uses an options page (using add_options_page) the plugin settings show up under the default "Settings" submenu.  I think I need to add the following CSS to get the bubble to show up,   1   and tie into the global $submenu. The problem is I cannot use a hard-coded array value for the menu since each site will have different values.  So I cannot use $submenu[80][10] .= 1  How can I find my plugins submenu value, do I have to loop through the array and match the string values?  Also even when I hard-coded the values I could not get the bubble to show up.  //adding plugin to menu add_action('admin_menu', 'sec_plugin_checker');  function sec_plugin_checker() {   add_options_page(' Plugin Checker', 'Plugin Check', 'activate_plugins',    'sec_plugin_check', 'sec_checker');   // the conditional where I want the bubble to appear  if (!empty($matches)){      echo "Match found !
";      global $submenu;     foreach( $submenu as $item ) {      $item[41][20] = sprintf( __( 'Updates %s', 'sec_plugin_checker' ),                   "                  1");           }   }   and here is what a var_dump($submenu); looks like,   ["options-general.php"]=> array(9){ ...  [41]=>     array(4) {       [0]=>       string(20) "Plugin Check"       [1]=>       string(16) "activate_plugins"       [2]=>       string(21) "sec_plugin_check"       [3]=>       string(23) " Plugin Checker"       ...        }


If I disable ueif on Windows 8, can I use the Windows installer?

I have a Lenovo u430 laptop and would like to dual boot Ubuntu and Windows 8. If I disable ueif can I do that and install Ubuntu with the installer?


Is power-associativity finitely axiomatizable?

Let the signature under consideration be $(S,*)$, which is the signature of magmas. Power-associativity can be axiomatized by an infinite set of equations. Can it also be axiomatized by a finite set of equations, or if not, a finite set of first order axioms?


I have a record set as below:  company_id      po_date     po_number       supplier_company_id  1             01/01/2017        1000          20 1             02/01/2017        1001          20 1             03/01/2017        1002          20 2             01/02/2017        1005          30 2             02/02/2017        1006          30 2             03/02/2017        1007          30   and I want to return the records for the latest dates per company_id  company_id      po_date     po_number       supplier_company_id  1              03/01/2017       1002        20 2              03/02/2017       1007        30


How to force Mac (Yosemite) to use USB Bluetooth instead of internal?

I'm on an older Mac Pro, and I bought the ASUS USB-BT400 so that I can use Yosemite's Handoff feature. The problem is, I don't know how to disable the internal Bluetooth and force my machine to use the USB Bluetooth instead. I searched around but didn't find anything that worked.


I have downloaded latest version of Ubuntu 16.04 and am unable to initialize root login administrative access permissions inside of Terminal ?


Schengen visa from country with less days of stay

Can I apply for a Schengen visa from Germany, enter there and stay for 2 days and go to Poland for 10 days and exit there? As my itinerary is dependent on a friend who's coming from US, I am assuming that this might become the case.


Detecting memory leaks & dumping statistics in python

I am looking for python memory debugging techniques? Basically I am looking at tools available for python and see what data we can look at when a python process is taking lot of memory? I am aiming to isolate such memory eating process and dump statistics.


Can I access internal microphone input level via Terminal?

I am interested in using my old MacBook as an audio baby monitor. My imagined workflow is to set a noise threshold for the internal microphone in the MacBook when baby is stirring or whining and to use Messages to text me or my wife when the threshold is reached.  When I'm looking in System Preferences, I can see the Input level for the microphone is picking up noise, but how can I get a quantifiable number in Terminal?  I've seen online about osascript -e "get volume settings" to access a numeric value for how sensitive the microphone should be set, but I can't find a way to access how loud of an input is coming in at any given time.  Any ideas out there?


What is this sci-fi film involving a time/teleportation machine and a boy in a spacesuit

There was a time-machine (or teleportation machine) in a spherical geodesic shape, made of metal with large panels, it was dark grey or dark blue. A pilot used the machine while wearing a spacesuit, the machine shook violently when activated. The pilot was a white american man. He was either transformed into the body of a child or replaced with a child, perhaps his younger self, early teenage years. It might be the case that the spacesuit was lost and an unrelated child found it. The child walks home down a sidewalk in the oversized spacesuit; This was in a suburb somewhere with a hedgerow on the side of the sidewalk The spacesuit had a very large rim around the neck, and correspondingly large hemispherical helmet, it was very baggy on the child. I think after the machine's operation the pilot's coworkers started searching for him.   I think I watched this in the late 90s or early 00s on British television, although I'm quite sure it was an American movie, probably from the 90s.


How to cite subfigure numbers for caption of the parent figure?

I am trying to cite subfigure numbers in the caption of the parent figure as shown in MWE. It works but I always get the following error which I cannot remove:  Error  Line 15: Argument of \caption@ydblarg has an extra }. [...f{fig:sub_fig_B} B \subref{fig:sub_fig_C}}] Line 15: Paragraph ended before \caption@ydblarg was complete. [...f{fig:sub_fig_B} B \subref{fig:sub_fig_C}}]   MWE  \documentclass{elsarticle} \usepackage{graphicx} \usepackage{subfig} \begin{document} \begin{figure*}     \centering     \subfloat[]{\label{fig:sub_fig_A} \includegraphics[width=67mm]     {example-image-a}}     \subfloat[]{\label{fig:sub_fig_B} \includegraphics[width=67mm]     {example-image-b}} \\     \subfloat[]{\label{fig:sub_fig_C} \includegraphics[width=67mm]     {example-image-c}}     \subfloat[]{\label{fig:sub_fig} \includegraphics[width=67mm]     {example-image}}     \caption{Caption for \subref{fig:sub_fig_A} A \subref{fig:sub_fig_B} B \subref{fig:sub_fig_C}}     \label{fig:test} \end{figure*} \end{document}   How to remove this error?


Is it possible for Salesforce Platform Events to cross orgs intentionally?

Let's say, for whatever reason(s) I have two orgs (maybe not me personally, but two businesses doing business together).  Let's say org A publishes a Customer_Event__e (for whatever reasons).  Would it be possible for org B to subscribe to events on org A?  (I mean, WITHOUT creating some proxy on another platform that could catch the event and forward it in some other fashion.)


Why do my "How to" questions often get renamed to "How do I"?

On the other hand  that fix mistype in "How to" got though community approval.  What is the rule about "How to" and "How do I"? Why are some tutorials called "How to"s?


Are semicolons mandatory in a non-bulleted list after a colon?

Are semicolons required (rather than commas) in a list after a colon when the list is not bulleted? I was told that it was a rule, but I can find no authoritative prescriptive source.   Consider the example sentence below.     The following are unclear: whether a change in Rule C is regarded as a violation; whether it is possible to add conditions to rule D in Category 5 when submitting a report to the Committee; and whether Rule G and Rule H satisfy the professional requirements.    If there is no potentially confusing internal punctuation in the list elements, and if parallel construction (e.g., whether . . . whether . . . whether) shows clear demarcation, are commas not sufficient?


The handsome young teacher fell into easy banter with his students, who were not much younger than he/him.   Should this use "he" or "him"?


Open Link in different Profile in Firefox

I'd like to have Firefox open Links in another Profile. Preferrably in way that I can set some URLs to open in the same Profile.     My use case:  I've set up a Firefox profile without navigation bar, which holds all my messenger web apps, which is started automatically on startup.  If someone sends me a link via messenger, it is opened in this profile though, which isn't practical without the navbar and in terms of workflow. I'd like to have a setup, where all the internal messenger links(say *) are opened in the messenger profile and all external links are opened in my default Firefox profile.  Is there a way to accomplish this?


I am looking for some direction to see if there is an equivalent metric to a z score that could be used to quickly identify individual values in a non-normal distribution that are not likely to occur (for example, + or - 3 standard deviations).    This is really basic with a normal distribution but the data I'm dealing with is highly skewed with a very large amount of values at 0.  Specifically, my data contains the geographical distance between two events that occur.  Many times, the events take place in the same location, leaving a huge volume of values of 0, with the rest of the distances decreasing rapidly in frequency.  I attempted to do a log transformation but this still does not work well with the values of 0.    Again, is there something like a z score that can be used on non normal data?  If not, what is the best way to find the values that are not likely to occur?


Why does process substitution result in a file called /dev/fd/63 which is a pipe?

I am trying to understand named pipes in the context of this particular example.  I type <(ls -l) in my terminal and get the output as, bash: /dev/fd/63: Permission denied.  If I type cat <(ls -l), I could see the directory contents. If I replace the cat with echo, I think I get the terminal name (or is it?).  echo <(ls -l) gives the output as /dev/fd/63.  Also, this example output is unclear to me.  ls -l <(echo "Whatever") lr-x------ 1 root root 64 Sep 17 13:18 /dev/fd/63 -> pipe:[48078752]   However, if I give,ls -l <() it lists me the directory contents.   What is happening in case of the named pipe?


IMO 1984: Prove that $0 ≤ yz + zx +xy −2xyz ≤ \frac {7}{27}$, where $x,y$ and $z$ are non-negative real numbers for which $x + y + z = 1.$

I tried to solve this inequality because I find exotic.  Actually, I didn't look at the right solution.  Because before I look at the right solution, I want to know if my solution is right or not.  Prove that $0 ≤ yz + zx +xy -2xyz≤\frac{7}{27}$, where $x,y$ and $z$ are non-negative real numbers for which $x + y + z = 1.$  Attempts: If $x=0$. The left side of the inequality is correct. So, I can accept $x,y,z≠0$. It is enough to prove $\frac 1x+\frac1y+\frac1z≥2$ We have,  $x+y+z≥3\sqrt[3]{xyz}\Longrightarrow xyz≤\frac1{27}$ $\frac 1x+\frac1y+\frac1z≥\frac3{\sqrt[3]{xyz}}≥9≥2$ The left side proved.  It is obvious at least one of the numbers is less than $\frac 12.$  So, we can choose $y$, such that $y≤\frac 12$.  Therefore, we have  $yz + zx +xy −2xyz ≤ \frac7{27}$ $x(y+z)+yz(1-2x)-\frac7{27}≤0$ $x(1-x)+y(1-x-y)(1-2x)-\frac7{27}≤0$ $x-x^2+y-xy-y^2-2xy+2x^2y+2xy^2-\frac7{27}≤0$ $x^2-x-y+xy+y^2+2xy-2x^2y-2xy^2+\frac{7}{27}≥0$ $x^2(1-2y)+x(3y-2y^2-1)+(y^2-y+\frac7{27})≥0$ $2(\frac12-y)\left(x+\frac{y-1}{2}\right)^2+\frac{1}{108} (3y-1)^2(6y+1)≥0$  Of course, I'm not sure the solution is correct.  Can you verify the solution? Thank you.


Let $A, B$ be sets. Show that $\mathcal P(A ∩ B) = \mathcal P(A) ∩ \mathcal P(B)$.

Let $A, B$ be sets. Show that $\mathcal P(A \cap B) = \mathcal P(A) \cap \mathcal P(B)$.   I understand what this question is asking. The power set of an intersection equals the intersection of two power sets. I just have no idea how to prove it.


What is the correct way to completely remove an application?

I've searched the net for such information and found different command lines, like these ones:  sudo apt-get remove application sudo apt-get remove application*  sudo apt-get remove --purge application sudo apt-get remove --purge application*  sudo apt-get purge application sudo apt-get purge application*   So, what is the correct way? Is it necessary to use that "*"?  After that, I also found these commands:  sudo updatedb sudo locate application sudo rm -rf (file/folder name)


Not only i want to low level format it, i want to reinitialize it, factory reset style, like some kind of HDparm but in the deepest level, like, absolutely destroying every sector and or hard drive settings.


Distro question - Which (current) linux distro works well with older laptops

I'm sorry, but this is going to be somewhat vague for now. I'll update this within 24 hours with more details, or as soon as they are available. Whichever comes first.  I am enrolled in an engineering class that requires a year-end presentation. My presentation is a couple weeks out, and I've just hit a roadblock. My previous plan was to haul in and hook up my desktop, but school policy changed and I'm not allowed to do that any more. Instead, my dad has allowed me to use an old laptop for my presentation.  However, this is where the problems begin. His laptop is an XP machine. The software I need for my presentation is PowerPoint (or Libreoffice Impress), Logger Pro (I have the .deb packages), and a couple more programs that I wrote, that will ONLY work on Linux.  My dad has a Dell Vostro 1500, which was released in 2007. Specs are   He is offering me the laptop he used for a couple years before that, so something probably released in the 2004-2005 range. I don't have specs right now (or even know what laptop it will be, just that it was an XP box and could run CAD software).  I am looking for a distro that has/can/is:   Run LibreOffice Install Debian Packages Run Scripts that can listen to hardware Minimal system footprint Preferably Debian or Ubuntu based, as I have experience with these distros   If the older laptop works, what would be a good candidate for a distro that can do the above, while using minimal memory?  If the older laptop does not work, what distro could do the above on a Dell Vostro 1500 () quickly and efficiently?  I am aware of options such as Puppy Linux and Tiny Core Linux, but those are not good options. While they run fast, my scripts need something based off of Ubuntu or Debian to run and display correctly.  UPDATE: The older laptop cannot be found, so I am using the Dell Vostro 1500. I have been allowed to partition the HDD, and added a 30Gb (the other partition has 10Gb free space left) partition. I installed Xubuntu (I have 2Gb of ram, and decided to capatilize on it), Logger Pro, Libreoffice, and other software I need. In fact, I am editing this from the laptop.  Some slight issues were had with the trackpad (now THAT was fun to fix, without access to a mouse) and WiFi, but those were issues commonly had and easily fixed.


Assume that a typical computer manufactured by a company lasts 10 Months and that the standard deviation is 50 days. Computer life follows a normal distribution. What is the probability that a computer made by this company will last at most 1 Year?  Assumption is that one month has 30 days.  Can you please explain how this is calculated ?  Thanks


Steps to Recreate:   Have enough rep to use some of the review queues. Ignore a popular tag. Go to your profile-> prefs-> check 'hide ignored tags'. Open a review queue.   You will get questions from your ignored tag(s) in the review queue.  Personally, I ignored a tag on Movies.SE (and Scifi.SE) for a film that is out elsewhere in the world, but not locally.  It's a simple way to avoid being exposed to spoilers.  I then load up the First Posts review queue on Movies.SE, and I get an answer to a question about the end of the film.  Can the review queues be altered to skip posts on your ignored tags when you have the 'hide ignored tags' option enabled?


Alternative US INTL keyboard layout which is not "clever" with the quotes?

I'm using the US International keyboard layout in Windows 10 because I need a US layout for easily accessible "programming" keys (<,>,[,],(,),|,;, and so on..) together with the ability to write German umlauts ('ä', 'ö','ü', 'ß', ...)  Now I learned that Microsoft uses the "US International" layout to demonstrate it's superior cleverness and cripples fluent writing by introducing smart braces.  Trying to write "US" results in ÜS, writing back ticks, single quotes and double quotes behave differently, and there are many more features which make it impossible to seamlessly switch between systems with "US international" keyboard layout installed.  Answers to  question suggest to just switch to "US" layout. But that way I don't have the "US INTL" layout anymore of course.  Are there alternatives? Can I deactivate this "feature"? (I just realized that trying to write a double quote even behaves differently the second time I try it!)  @Microsoft: Thanks, this is just as useful as Notepad, the Middle-Mouse-Button-Navigator and the CapsLock key (which I know is not your invention)


Blank images on copy paste from pdf to image editor or LibreOffice

Lately I have to extract few specific images from .pdf files and save them as image file. For example, the following is the image copied from a PDF (right click and copy image using Ctrl+C).    When I paste the same either in LibreOffice Writer or an image editor like KolourPaint, I end up with a blank image something like this. Can anyone suggest how I can work around this issue?


Minimum value of $2^{\sin^2x}+2^{\cos^2x}$

The question is what is the minimum value of $$2^{\sin^2x}+2^{\cos^2x}$$ I think if I put $x=\frac\pi4$ then I get a minimum of $2\sqrt2$. But how do I prove this?


How to get bokeh effect using compact camera?

Guess the question itself sums it up, Is it feasible? If so, how?


i am not able to install hp laserjet 1007/8 in ubuntu 12.04, please help

i have installed ubuntu 11.10 and 12.04 in two pc earlier running in win xp. the printer hp laser jet 1007/1008 are not detected and the problem is not solved  even after connected to internet. please help.


Misleading Definitions and Unanswerable Problems in Spivak's Calculus

Spivak's Calculus 4th edition, Chapter 3 Functions, Page 47:  DEFINITION: A function is a collection of pairs of numbers with the following property: if (a,b) and (a,c) are both in the collection, then b = c; in other words, the collection must not contain two different pairs with the same first element.  He continues:  This is our first full-fledged definition, and illustrates the format we shall always use to define significant new concepts. These definitions are so important (at least as important as theorems) that it is essential to know when one is actually at hand, and to distinguish them from comments, motivating remarks, and casual explanations. They will be preceded by the word DEFINITION, contain the term being defined in boldface letters, and constitute a paragraph unto themselves.  Ok got it. Fast forward to the problem set, I'm up to problem 25)  25) Find a function f(x) such that g(f(x)) = x for some g(x), but such that there is no function h(x) with f(h(x)) = x  I asked about this on MSE (see ), and after much discussion came to the resolution that the problem 25 is impossible given the above definition of a function. In summary, the problem is that in order to find f(x), you need to choose f(x) to be a non-surjective function, which requires the concept of codomain. However the above definition does not include the concept of codomain, only domain and image, hence it is impossible. My question is: What was Spivak thinking (and I mean literally)? How did Spivak intend for us to solve this problem? Is it an error on his part? Or is there a way to intuitively infer from the above definition that functions must be specified a codomain (codomain, not image) in order to be defined? If I had the solutions book to Calculus 4th Edition, this would greatly help answer my question, but I can't find it anywhere for free.


I have a form which when submitted, an array will be passes. The elements inside that array will be separated using rxml. This is how I tried:  $options = $this->request->data('options');  $count = count ($options); $rxml = "<rslist>"; for ($i = 0; $i < $count; $i++) {      $trimmedOption = trim($options[$i], "    "); $rxml = $rxml.'<rs option="'.$trimmedOption.'" />'; } $rxml = $rxml . "</rslist>";   When an element is converted in to a string, first it gets trimmed, because there is some white space in right side of the string. Like this opton-1. In order to remove that space, I used that trim option. But, this is not working. I tried:  str_replace(' ', '', $options[$i]); rtrim($options[$i]);   too. But, nothing worked. That string got saved with that extra space only. So, what should I do? What should I change?


Ubuntu on XPS13 9333... Want to add Windows 8.1

When I bought my XPS13 9333 I got angry with Windows, wiped it, and installed Ubuntu.  My son now wants Windows for gaming (thanks Lego World!).  I don't know my product key (but expect I can get it from Dell) and need a detailed "how to" on partitioning and installing Windows.  I think I wiped it so clean that I can't restore it to factory settings and don't have any recovery disks (may need to order from Dell).  Any help is appreciated! /M


8GB USB pen drive showing 700MB after formatting

My 8GB pen drive is now showing 700MB after I formatted it. I've created Ubuntu Desktop bootable USB drive using Power ISO.   After I formatted it. Now it's showing 700MB. Why is that? I'm using Windows 7 Ultimate.


Double Strike with Lifelink that destroys its blocker in the first strike phase

Say I have a 5/5 creature with double strike and lifelink. I attack with the 5/5 and my opponent blocks with a 1/1. The creature is killed by the damage in the first strike phase and I gain 5 life. Do I gain an additional 5 life in the normal damage phase?


Removing Kubuntu from External Drive and Reformating

For some obscure reason, which seemed like a good idea at the time, I installed Kubuntu onto an external USB 1TB drive. It never worked.  Now, I would like to use that drive as storage but cannot delete any of the installation or boot files. I also cannot upload any other files onto it.  How would I reformat the whole drive so it can be used as general storage which can be read by linux, android and windows devices  Many thanks


$(this).click(); Function does not work with elements loaded via ajax

I have a few .filter-options-title elements that are loaded via ajax with below jquery. Once added to the DOM i use an each function to shrink some if their location is below a certain point on the page however the simulated click function does not seem to be firing on the new elements.   Clicking the elements directly on the page does fire the click event so i believe they are bound to the event fine.  How can I get around this?  $.ajax({   url: filterurl,   type: "get",   type: "get",   data: {     ajax: "1",     filters: "1"   },   dataType: "json",   success: function(result) {     $(".filterloading").remove();     $(".sidebar").prepend(result['html']['filters']);     $('.filter-options-title').each(function(i, obj) {       if ($(this).offset().top + $(this).outerHeight() > ajaxMode.calculateHeight()) {         if ($(this).attr('aria-expanded') == 'true') {           $(this).click();         }       }     });   },   error: function() {     alert("Error please refresh page."); // inform the user about error   } });


Show that if $A \in M_{nxn}(k)$ and $det A \neq 0$ then for each matrix $B  \in M_{nxn}(k)$:  $AB$ and $BA$ are similar. Give an example $A,B$ for which $AB$ and $BA$ are not similar.   If $AB$ and $BA$ are similar then I have matrix $C$ for which $AB=C^{-1}(BA)C$. However I don't know how to prove that this matrix exist if I know only that $det A  \neq 0$. I thought also about a fact that $tr(AB)=tr(BA)$ but I think it laso is unhelpfull for me.Can you get me some tips which facts are helpful for me to do this task?


How to chain make command with git clone?

I want to automate pulling git repo and building that repo unattended.  Is there any way I can clone repository and run make immediately after running git clone? Something like:  git clone << myrepo >> && make


Noticed this many times but was too lazy to post.  So I see a message in my inbox that bounty is completed and now in grace period, however its title says that "bounty expiring soon"    Wonderful (not wonderful of course). I click it, and... guess what?    Ok. So 49 mins left. But the main problem is that time traveling is . (if it is not, please forbid it).