Is mandatory to use a prepared statement in a SELECT query?

If you use htmlspecialchars() when receiving input from the user, like:  $email = htmlspecialchars($_POST['email']);   Should you use a prepared statement if the query is just a SELECT one?


How to copy files from a directory to desktop by directly dragging it in Ubuntu 20.04.1

I'm new to Ubuntu and I try to drag a file directly from a fold to the desktop in order to copy the file as one can do in Windows. But it doesn't work. I know how to do it in terminal, and I have disabled experiment view and is able to drag files between folders to copy them. I'm justing wondering why I can't drag and copy it to the desktop? Is it not supported in Ubuntu?


Hello I've been doing some HashSet Questions for the past week or so. The last Question asks me to create iter method for my HashSet. Here is my code:  class HashSet:     def __init__(self, capacity=10):         self.table = [None] * capacity      def add(self, item):         h = hash(item)         index = h % len(self.table)          if self.table[index] == None:             self.table[index] = LinkedList()           if item not in self.table[index]:             self.table[index].add(item)      def __iter__(self):         table = []         ptr = None         for i in range(0, len(self.table)):             if self.table[i]:                 ptr = self.table[i].head                 while ptr != None:                     table.append(ptr.item)                     ptr = ptr.next         return sorted(table)   It doesn't seem to work and it gives me an error: TypeError: iter() returned non-iterator of type 'list'. What am I supposed to return??  Input: 7 20 30 40 50 60 70 80 90  Desired Output: [20, 30, 40, 50, 60, 70, 80, 90]  Values inside table var are correct I tested that with print() statement. How do I fix it ?


Object Oriented Programming in C++ - Header Files

I recently switched to C++ after using Java for a good amount of time. However, I have some difficulty grasping the entire concepts of using header files along with class files.  Firstly, aren't headers just like interfaces in the OOP context?  Secondly if I have the following piece of code why do I get an error:      //CExample.h     //--START OF HEADER--               #ifndef CEXAMPLE_H     #define CEXAMPLE_H     #include <string>      class CExample{     private:        string name;     public:        CExample();       ~CExample();        string getName();     };     #endif     //--End of Header--      //CExample.cpp    //--Start of class file--     #include "CExample.h"    string CExample::getName()    {        return name;    }    //--End of class file--   I get the error: 'string' does not name a type.  So as a summary of my confusion I have the following questions:  1) What's the best and healthy way of using includes in the headers.  2) What's the concrete difference between using "" and <> for includes. (Yes I have read plenty of c++ tutorials but the explanations are somewhat vague -- they say it depends on the directory location etc -- I would like some c++ veteran to make a clear statement if possible)  3)Are there are naming conventions enforced in C++? For example in Java, you need to have the class name match the file name in which is is defined.


Novel search: A man searching for his brother in Africa starts a chase through different realities/dimensions

I might be mixing up several books, I hope I'm not, it's been 20 years since I read the books.  I want to say it was a series of books. Each book could have been written by a different writer.  From memory it starts off in the late 1800's/early 1900's a man has gone to Africa to search for his lost brother. Weird/implausible stuff starts happening as they travel up a river, I want to say the Congo, and eventually they enter another realm. As they chase after clues to his brother they traverse a reality roughly each book.  At some point I want to say there is train imagery used as well as an iceberg with reference to Mary Shelly's monster(I could be mixing this up with another book)


Can't apply SELinux file context to paths with symlinks

I have a solution that is being installed in an enterprise environment. The solution and its deployment guide are designed to installed on a RHEL7/CentOS7 server with SELinux enabled and components being installed to locations according to the Filesystem Hierarchy Standard.  One of the clients however has surprised us by stating that all 3rd party solutions must be installed to a /apps directory since they back this up according to policy.  To avoid deviation for this specific client, since it would require significant modifications to the solution, we decided the best approach would be to create a new directory in the /apps directory for /optand create symlinks upfront from the true /opt and apply the same SELinux content to it (usr_t) e.g.:  ls -laZ /appl/opt drwxr-xr-x. root     root     unconfined_u:object_r:usr_t:s0   . drwxr-xr-x. root     root     unconfined_u:object_r:default_t:s0 .. drwxr-xr-x. product product unconfined_u:object_r:usr_t:s0   product  la -laZ /opt drwxr-xr-x. root root system_u:object_r:usr_t:s0       . dr-xr-xr-x. root root system_u:object_r:root_t:s0      .. lrwxrwxrwx. root root unconfined_u:object_r:usr_t:s0   product -> /apps/opt/product/   Certain components of the product are accessed via Apache HTTPD and require the httpd_sys_content_t context to be applied to them.  The files are located at /opt/product/wwwstatic/ (which in reality is /apps/opt/product/wwwstatic/).  The deployment guide specifies the following commands to run:  semanage fcontext -a -t httpd_sys_content_t "/opt/product/wwwstatic/*" restorecon -Rv /opt/product/wwwstatic   which restores the contexts on a standard installation but in this environment, because of the symlinks, it fails.  If you modify the commands to include the /apps directory it works but deviates from a generic approach.  The contents of /etc/selinux/targeted/contexts/files/file_contexts.local is:  # This file is auto-generated by libsemanage # Do not edit directly.  /appl/opt/.*    system_u:object_r:usr_t:s0 /appl/srv/.*    system_u:object_r:var_t:s0 /opt/product/wwwstatic/*    system_u:object_r:httpd_sys_content_t:s0   Is there a means of modifying the arguments to semanage or restorecon commands so that this will work for symlinks (as well as normally) or have I a fundamental misunderstanding of how SELinux applies file contexts?  I believe this question differs from  since it is about applying contexts to files in subdirectories from symlinked directories instead of applying contexts to the symlink file itself.


Solving linear congruence $2x + 11 \equiv 7 \pmod 3$

I'm having some troubles understanding the solution (going from step $2$ to step $3$) of this linear congruence equation. Here's the problem with the solution:   Solve the congruence $2x + 11 \equiv 7 \pmod 3$.   First, we reduce all the coefficients $\pmod 3$:  $$2x + 2 \equiv 1 \pmod 3. \tag{1}$$  Next, we add $1$ to both sides, using the fact that $2 + 1 \equiv 0 \pmod 3$:  $$2x \equiv 2 \pmod 3. \tag{2}$$  Finally, we multiply both sides by $2$, using the fact that $2 · 2 = 4 \equiv 1 \pmod 3$:  $$x \equiv 1 \pmod 3. \tag{3}$$  That is, any number in the set $\{\ldots, −5, −2, 1, 4, \ldots\}$ will solve the original congruence.    Like I said my problem is the step between $(2)$ and $(3)$. If I multiply both sides of $(2)$ by $2$ I get:  $$4x \equiv 4 \pmod 3.$$  Now, I understand that $4$ is congruent to $1 \pmod 3$ so the RHS "simplifies" to $1 \pmod 3$ but I don't understand why the LHS "simplifies" to $x$. Can someone help me with this?


GRUB problem: 12.04 not booting without USB drive

First of all: this is not a duplicate of the all the " questions.  Problem:  When booting, the system will not boot unless the installer USB flash drive is present. If I boot without the USB drive, the screen goes black AFTER GRUB lists the different configurations available - so GRUB is on the correct disk, its what it does next that seems to be the problem.  With the USB drive inserted, its access light starts flashing while the system boots in a normal manner.  And yes: I have tried booting from the USB drive directly and then I get the "live" version, so I have not installed the OS on the flash drive by mistake :)   I have tried sudo grub-install /dev/sda and sudo update-grub just for fun, but nothing changed.  System in short:  Ubuntu 12.04 64-bit. i3 processor. UEFI bios. 128Gb SSD drive. The SSD has a 47 Mb EFI partition and the rest mounted as '/' (XFS).


Why doesn't the '?' regex character produce a match in sed?

I have a string similar to ../../sdd1 and trying to match sdd from here. I'm trying to use the following sed command:  echo "../../sdd1" | sed 's:.*\([a-z]\{3\}\)[0-9]?:\1:'    and it does not produce a match. But when I use   echo "../../sdd1" | sed 's:.*\([a-z]\{3\}\)[0-9]\{0,1\}:\1:'   then I get my match, sdd.  My best guess is that I should escape the ? as well, similar to the curly brackets - I tried it and it works, but I don't know why.  So the question is, why does the [0-9]? regex not match the 1 from sdd1, or why do we have to escape the ? and the curly brackets?


How to get files from a certain folder into my TeX-file without knowing the filenames?

I have a folder with couple hundred figures (and only figures in there): How can I import all of them into my tex-file without knowing the filename in a code like \includegraphics{filename} (working with LuaLaTeX?  I would like to have the filename as caption.  General MWE:  \documentclass{article} \usepackage{graphicx,caption} %folder for the figures is `/figures/`  \begin{document} %repeat from here for each file in folder `figures` \begin{figure}[!htb] \includegraphics[scale=1]{figures/`filename`} \caption{`filename`} \end{figure} \end{document}


Are there any peer-reviewed papers on the maximum waiting time to be considered "user real-time"?

Are there any scientific papers about any study performed on what is considered a maximum waiting time for an activity to be considered "user real-time" (not software real-time).  I was looking at something along the lines of "maximum waiting time for a web page to render" and the user's perception of real-time.  For instance empirically, we can state that waiting 200 ms would be real-time whereas waiting 10 seconds would not, but I was hoping to find some citation for it in scientific literature.  I've tried some resources (eg Google Scholar) but to no avail.  Thank you.


I am ready to try Ubuntu 11.10, how do I upgrade to it from 11.04?


I want to install Xcode SDK for iPhone app development on my Windows 7 PC, does any one know is this is possible?


$p$ a prime and $A=\{\frac{a}{b}\in\mathbb{Q}:p\text{ does not divide } b\}$ is a PID and decribe its units

Let $p$ a prime and $A=\{\frac{a}{b}\in\mathbb{Q}:p\text{ does not divide } b\}$. Prove that $A$ is a Principal Ideal Domain and describe its ideals. Can anyone help me to solve this exercise? any idea will help. Thanks in advance!


Checking single bits in a bitmask using std::pow

I have the following define to check an unsigned int bitmask for a certain bit. Is there a more straightforward way (that doesn't include power of calculation) which I'm not aware of?  This is my :  #include <iostream> #include <cmath>  #define IS_BIT_SET(x) (foomask & (int)std::pow(2, x-1)) >> x-1 == 1   using namespace std;  int main() {      unsigned int foomask = 0xFFFFFFFF;     if(IS_BIT_SET(1))         cout << "Bit 1  is set" << endl;      if(IS_BIT_SET(32))         cout << "Bit 32  is set" << endl;      return 0; }


Quotes missing around title of arXiv papers (biblatex + biber)

I am using biblatex and biber. Here is a sample LaTeX file.  \documentclass[11pt]{article} \usepackage[backend=biber,firstinits,style=numeric-comp,maxnames=99]{biblatex} \bibliography{longnames.bib,test.bib}  \DefineBibliographyStrings{english}{%   references = {Selected Publications},  } \begin{document}  Ref.~\cite{CJS:2013} and~\cite{BCW:2012}.  \printbibliography \end{document}   The reference BCW:2012 looks like this in the bib file.  @online{BCW:2012,   author    = {B and                C and                W},   title     = {Musings and machinations},   eprinttype   = {arXiv},   eprint    = {1234.5678},   eprintclass = {cs.DS},   year      = {2012} }   The problem is that the title "Musings and machinations" doesn't have quotes round it when rendered whereas all other (non-arXiv) papers do.  What am I doing wrong?  I am using biber version 0.9.9.


Write all PHP errors, warnings and notices to error_log

Drupal catches PHP warnings and notices to log them via dblog or syslog. As a result, there are two places to monitor for PHP errors (with the watchdog UI not well suited to cater for any large number of notices).  Is it possible to prevent this behavior and have ALL php errors be logged to the error_log defined in the php config?


Select the column down to the first blank row in the adjacent column?

In Excel 2010 I have several columns with data.  I insert a column, and type a formula in the top cell of that column.  I want to fill the formula into the remainder of the column, down to the same row as is filled for the other columns.  Once the selection is made, I could use Paste, or Ctrl + D to fill down.  My issue is with selecting row 1-N quickly (without the mouse).    Think of a sheet with 10k rows or more.  My current inadequate solutions are:   Use the mouse by scrolling and shift clicking on the last cell Use the arrow key while holding shift until reaching the last cell Use the page down key while holding shift until reaching the last cell Double click the formula cell handle to fill down (uses mouse) Ctrl + T to make it a table, then Ctrl + Space to select the data, then have to change it back from a table   Ctrl + Shift + Down works if the column has data in it, but if the column is empty it goes to the bottom of the sheet.


How to set a routing table that prefers wlan dhcp interface as default route?

eth0 has a static IP set in /etc/interfaces  wlan0 gets it IP dynamically  How can I change my routing table and where would I put the command to always make wlan0 the default route so internet access will work?  Right now I can ssh into the box using either eth0 or wlan0 but internet access gets routed through eth0 always which does not work.  Also, are auto and allow-hotplug contradictory options?  Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface default         192.168.20.1    0.0.0.0         UG    0      0        0 eth0 192.168.10.0    *               255.255.255.0   U     0      0        0 wlan0 192.168.20.0    *               255.255.255.0   U     0      0        0 eth0  source-directory /etc/network/interfaces.d auto lo iface lo inet loopback auto eth0 allow-hotplug eth0 iface eth0 inet static         address 192.168.20.2         netmask 255.255.255.0         gateway 192.168.20.1 allow-hotplug wlan0 iface wlan0 inet dhcp     wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf allow-hotplug wlan1 iface wlan1 inet dhcp     wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf


What is the cartesian product of an empty set of sets?

Let  $$Y=\prod_{X\in \emptyset}X$$  What is $Y$? The empty set? The singleton set?  EDIT: Here is another way of reading the conclusion in the comments so far:  $Y$ is the set $$Y=\{(x_1,...,x_n) | x_1\in X_1,...,x_n\in X_n, \text{ for } X_1,...,X_n\in \emptyset\}$$  But the only tuple satisfying this is $()$, i.e. the empty tuple. Hence $Y$ is the singleton. Is this argument correct?


According to what I've learned from physics professors, no object can go faster than the speed of light. So if you have object A moving .8c one way and object B moving .8c the opposite way...relative to each other that is 1.6c? How do they appear to each other (or to a third stationary point in the middle in communication with each side)


TESTNG, how to validates test case results to pass fail status

Need help, my question here is how can I code it such when the result is not expected testNG will display the test case as failure/fail? if the result is expected test case result is passed? very new to TestNG. my problem here is no matter how many times I run, the testNG result is PASSED.  public class TestNgbasic{  DesktopOptions option=new DesktopOptions();    @BeforeMethod public void setup() { //  DesktopOptions option=new DesktopOptions();  // Start your outlook session     option.setApplicationPath("C:\\Windows\\System32\\calc.exe");       }  @Test public void testcase1 () throws MalformedURLException, InterruptedException {     WiniumDriver driver=new WiniumDriver(new URL("http://localhost:9999"), option);     Thread.sleep(5000);     driver.findElement(By.name("Seven")).click();     driver.findElement(By.id("plusButton")).click();     driver.findElement(By.name("Eight")).click();     driver.findElement(By.id("equalButton")).click();     Thread.sleep(5000);     String result = driver.findElement(By.id("CalculatorResults")).getAttribute("Name");             if ("Display is 15".equals(result))     {         System.out.print("Pass");        }     else          System.out.print("Fail");    }      }


Does the Windows version of MAGMA have a memory limit?

Sorry if this isn't the best place to ask support type MAGMA questions, but I haven't found a single forum or anything for MAGMA users to talk.  I have access to a copy of MAGMA which is running on a server at my school (the operating system is "Windows Server 2008 R2 Enterprise").  I've been told the server has 16GB of memory and there's no limit to how much a single user can use (I'm apparently usually the only person on this server).  But for some reason I keep getting system errors from MAGMA any time it tries to request more than ~1400MB of memory.  Does anyone know how I can determine if this is an error in the way the server is set up or if this is an inherent limitation of MAGMA?


I'm Wondering how about do you solve this question. I'm using a software Called TValue 5 to double check my work. Principal = $100,000.00 Interest = 3% annual, Compounded Monthly Payment Frequency is Monthly And the Duration is 36 Months Months that will be skipped are September, October, November and Decemer The Loan Starts in February, But that doesn't Information isn't necessary. Calculate Monthly Payment Amount    When I hit the Calculate Button, The Monthly Payment Amount is 4351.27 If anyone would Like to Double Check. I've tried a previous Method suggested to me but it was off by $200. If Someone could help to get closer that would be great


I recently found out that the Fibonacci Sequence appears in the Pascal Triangle. If it is written like so:  1  1 1  1 2 1  1 3 3 1  1 4 6 4 1  etc.  If we sum the diagonals, we get:  $1 = 1 $ $1 = 1 $ $1+1 = 2 $ $1+2 = 3 $ $1+3+1 = 5 $ etc.  Which is the Fibonacci Sequence  I realized that since Pascal's triangle can be written using the choose operation, I could find $F_n$ as such:  $F_n= \sum_{i=0}^{n/2}{{n-i}\choose{i}}$  My question is, can we prove this using induction? I tried but got stuck, here is my attempt:  For the base, when n=0, $F_0= \sum_{i=0}^{0/2}{{0-i}\choose{i}}= {0\choose0}=1$  Now, if we assume that the equation is correct for $n=k$, we must prove that the equation is true for $n=k+1$. Since we know that $F_{n+1}=F_n+F_{n-1}= \sum_{i=0}^{n/2}{{n-i}\choose{i}}+\sum_{i=0}^{{n-1}/2}{{n-1-i}\choose{i}}$.  Where do I go from here?


How do the timelines from Misfits align?

In episode 6 of the second season, we saw the fulfillment of a number of predictions made earlier in the series.  There are a number of spoilers involved in this question.  Specifically:      We saw the television footage announcing them as the "ASBO Five" being filmed, as well as the interview with Alisha, that we had seen earlier (season 2, episode 3) in Future Simon's apartment as part of the footage and pictures that Future Simon told Alisha was going to occur.  Alisha also reveals to Simon the identity of Future Simon, and their (inevitable?) relationship.   However...      At the end of episode 6, Curtis rewinds time, and they visit "The Big Cheese", at which point we see Curtis punch him.  They then end their community service, implying that none of the events of the rewound timeline ever occur (except in Curtis' memory).     In the Christmas Special, we see the gang several months later.  We find out that:     They are all poor (except, perhaps, Simon, due to the apartment from Future Simon) with mundane jobs.  It seems clear that they never became the "ASBO Five".  However, Alisha and Simon are now dating, and Simon knows about Future Simon.   How does this reconcile?  Does the end of episode 6 create a paradox with the information Alisha sees in episode 3?


CPU temperature too high but fan not running at max speed

My processor fan never runs on full speed event though my processor temperature is going so high. I am using HWMonitor (also speedfan) to record temperatures and my temperature readings in normal are as follows: Intel Core 2 Quad Q2800: Core # 0: 65 c Core # 1: 60 c Core # 2: 59 c Core # 3: 59 c  But during high usage like while playing a game or something it hits around 80+, I tried cleaning the grill and fan and putting new thermal grease but it didn’t help. HWMonitor further says: FANS PWM:  FANSWMIN0: 50%  And from the above reading I am guessing that my fan is running on 50% always and I think it is because it looks slow... Not really making any sound and you can feel any air blowing out of it if you put your hand in front of it. I tried SpeedFan but my motherboard isn’t supported… My BIOS also doesn’t have any such option all it has is: Advanced > Fan Control - Processor Zone Response - Normal - Processor Zone Damping – High - Auto Fan Detection – Disable - Fan Detection Error- Enable  My specs are as follows: Motherboard: Intel DG43NB [Version AAE34877-402] CPU:  Intel(R) Core(TM) 2 Quad CPU Q8200 @ 2.33GHz [Socket 775 LGA]  I want to know how to take my CPU temperature to normal again (probably by making my fan run to max speed)?  Just checked processor specification here:  And it says for Intel® Core™2 Quad Processor Q8200: TCASE 71.4°C  I am not sure about the usage of TCASE.


Number of views not available from an Android phone

When visiting any Stack Exchange site's mobile version from an Android device, the view counter is not displayed.  However, it is there on the full site view.


Noether's conserved charges: why are there not "spatially" conserved charges?

Noether theorem implies that there is a conserved current $j^\mu$ for every continuous symmetry of the action, i.e. $$\partial_\mu j^\mu=0 $$  to each conserved current we can associate a conserved charge  $$\partial_0j^0+\partial_ij^i=0 $$  integrating  $$ \partial_0\int d^3x\,j^0=-\int d^3x \,\partial_ij^i=0$$  by the divergence theorem and assuming that the current is $0$ at infinity  But wait, why do this only with the time component? Why can't I write (not using Einstein's convention)  $$ \partial_a j^a=-\sum_{k\neq a}\partial_kj^k\\ \partial_a\int dt \,dx_k\,dx_l \,j^a=-\int dt \,dx_k\,dx_l \,(\partial_tj^t +\partial_kj^k+\partial_lj^l)=0$$  with $k,l\neq a$ and where in the last equality I assumed the current is $0$ at infinity and sufficiently far in the future and past?   Is this something true but useless or is there something wrong in supposing the current is $0$ in the past and future (or in some other point of the derivation)? No field theory book or script I've come across mentions it.


Does a closed question cancel out that day's valid questions?

I'm trying to understand how exactly the new Curious badge works.  Suppose I have "valid questions" on June 28, June 29th, June 30th, July 1, and today, July 2. That would earn me a Curious badge under the described rules for five days. But suppose I also had a closed question on July 2. Would I still be eligible for a Curious badge based on "valid questions?" Or would that cancel today's valid question?  Edit" "Valid question" is my term for "good question" because of the potential for confusion using "good question" in two different


How do we properly check if a list is not null?  var ctx = new SP.ClientContext(baseUrl) var targetList = ctx.get_web().get_lists().getByTitle("ListName")


Example says it all:  x = [set()]*5 x[0].add(1) print x   yields:  [set([1]), set([1]), set([1]), set([1]), set([1])]   I understand what happened, but is this expected? Do I really need to use a loop to initialize a list with empty sets that are not aliases of each other?


How do I fix a Memorex USB 8GB flash drive that shows 0 B available?

Memorex USB 8GB drive that shows 0 B available. I don't know if it's mechanically broken or something is wrong with it.  Even disk part shows it as (See Disk 2)    Any ideas?  EDIT: The bios shows it as 2231 PRAM...


Deleting (Erasing) all Data from Failed SanDisk MicroSD Card

I've had two 32GB SanDisk MicroSD cards go bad recently.  One I was able to temporarily revive using the kind advice offered in this thread:   When I insert the other into a reader, it registers as 30.6MB (that's MB, not GB).  I've tried all sorts of software and other techniques to revive this card and retrieve the important data off of it (including FindAndMount and TestDisk).  Nothing has worked.  So I'm thinking of returning the card for a refund.  But first, I would like to make it unreadable by someone more skilled than myself.  Is there any way to do this, given that I cannot even format the card or get it to be recognized as more than 30.6MB?  I am looking for a method that does not entail the kind of obvious physical destruction that would jeopardize obtaining a refund from the retailer.  If Costco (where the card was purchased) accepts physically destroyed cards for return, then physical destruction is acceptable (but please have knowledge that they do).  Given two failures, I don't really want to send the card to SanDisk for replacement, because I no longer trust the reliability of their products.


Can I use Apple's San Francisco font (and other fonts) in my own text editor?

Can I use Apple's fonts in my Atom text editor.  seems to suggest I can't. Can anyone confirm this? I know, of course, Apple has no way of finding out if I do. I just don't want to use it if I'm not allowed to.


I have Ubuntu already installed on my computer that I just bought, and I have a copy of Windows 7. I like the feel of Ubuntu, and plan on trying it out, but I have many Windows-specific applications.   So, my question is, is it possible for me to dual boot Windows from Ubuntu. I understand people usually dual boot Ubuntu from Windows, but I have it the other way around. What do you suggest, or is this possible?


I'm a beginner (I bike 10km a day on a BSO MTB, but I guess that doesn't count) to long distance biking. I signed up for a 40km charity bike ride that happens next month. Thought I'd practice for it yesterday and found out my current bike is not up to it.  I'd like to invest in a decent bike (say 500 euros?). Is the BTwin rc 100 road bike any good? Or does anyone have suggestions for a decent bike, that will help me get into long distance biking?  Or should I get an MTB/hybrid?


Why are answerers not notified when there's a change in the question?

This question is different from  I'm asking "Why". And, putting a tag of 'feature request' to improve this site.   It has happened with me a couple of times. I answer the question and then after some hours or even days, the question is 'entirely' changed invalidating my answer. This might have happened with new users here as they are advised to improve their question (for better clarity) by seniors on this site, which is absolutely fine. But then, there should be some system that notifies all the answerers so that they can improve their answers as well (depending on the change).  One such example is here. This question first asked 'object' and its verb. Now which object was not so clear as the picture first showed a girl, a bag, infusion set, peripheral venous catheter etc. Since asked by a layperson, I answered it 'bag' and 'intravenous' or 'infusion'.  But then, after a day, the OP comes with a new image now clarifying what exactly he wants. I'd have answered 'IV bag' at first, if this image could have been in the original question.  This is okay in normal cases, but then, in some unfortunate cases, changing the question invalidates the answer completely. And then, it starts attracting downvoting.  There should be a system (and it does not take much pain) wherein the 'answerers' are notified whenever the question is being changed. 'Edit' in questions are not that frequent but whenever there are, they are the crucial ones.


I wonder whether it is formal to omit the subject in writing.  Must all sentences always have a subject when I'm writing an English test?  Ìs it colloquial and reserved to speech?


How to examine the relationship between categorical variables with several levels?

I would like examine if the job satisfaction of part-time workers is higher or lower compared to full-time workers.  My dataset consists of 4125 cross-sectional observations.  independent variable: employment status (1 = full-time, 2 = part-time)  dependent variable: job satisfaction (0 = Very dissatisfied, 25 = Dissatisfied, 50 = Neutral, 75 = Satisfied 100 = Very satisfied)  What kind of statistical test do I need for my analysis?  How could I incorporate (categorical) control variables (e.g. age, gender, tenure, etc.)?


How to interpret regression coefficients when the dependent variable is square root transformed?

I have problem with interpreting the OLS regression result with the dependent variable square root transformed when doing difference-in-differences analysis.  Our regression model is: $$ Y = β_0 + β_1 {\rm policy} + β_2 {\rm treated} + β_3 {\rm policy} \times  {\rm treated} + \ldots + β_i X_i + \varepsilon  $$ Where ${\rm policy}$ is a dummy variable indicate the policy change (0=pre-policy vs. 1=post-policy). ${\rm treated}$ is also a dummy variable indicate treatment or control group (0=control, 1=treatment)  To deal with the skewed distribution, $Y$ was square root transformed. Just wondering how can we interpret the result? Say, after the policy change, $Y$ was increased / decreased by ____?


Travelling to the US on B1 visa without a business purpose

(NOT a duplicate of )  Earlier last year, I went to the US for a business trip. In preparation for it, even though I applied for a B1/B2 visa, I was granted a (seemingly rare) straight B1 visa.  That visa was granted for 3 years and is going to be valid for a long time. Right now, however, I'm looking to make another trip to the US, this time to visit a friend (so, no business intentions). Does this mean I have to explicitly apply for another, B2, visa all over again? Or, if I do travel with my current B1, I can avoid the problem somehow?


If a sequence $(x_n)$ converges to $x$ in a metric space $(X, \rho)$, and converges to $y$ in a metric space $(X, \sigma)$, does it follow that $x=y$?  If not, what would be a counterexample, preferably on the space of continuous functions $C[0,1]$.


Kubuntu 12.10 - Do I have to install all the i386 packages in order to run wine on an amd64 machine?

Actually I have several questions here, but the main problem I want to solve is that, I need to run wine1.6 on my amd64 machine, which installed Kubuntu 12.10 for now.  First thing I noticed was that, wine1.6 asked for installing wine1.6-i386 as well.  I asked corresponding questions here, and in kubuntu forum.  My conclusion was that, in order to install wine1.6-i386, I also need to install a lot of :i386 packages, like libc6:i386, libgstreamer0.10:i386, and so on.  Is that correct?  Then, if it is correct, I got problems installing libc:i386.  I added multiarch settings using:  dpkg --add-architecture i386   and added [arch=amd64,i386] after "deb " in all my source.list configuration files.  Of course I remembered to run:   apt-get update   Then I tried to   apt-get install wine1.6 wine1.6-i386 wine1.6-amd64  and put all the i386 packages it requested after this install commands.  Now I got error messages like:  The following packages have unmet dependencies: libc6 : Breaks: libc6:i386 (!= 2.17-0ubuntu5) but 2.15-0ubuntu20.1 is to be installed libc6:i386 : Breaks: libc6 (!= 2.15-0ubuntu20.1) but 2.17-0ubuntu5 is to be installed libgl1-mesa-glx : Breaks: libgl1-mesa-glx:i386 (!= 9.1.3-0ubuntu0.3) but 9.0.3-0ubuntu0.4 is to be installed libgl1-mesa-glx:i386 : Breaks: libgl1-mesa-glx (!= 9.0.3-0ubuntu0.4) but 9.1.3-0ubuntu0.3 is to be installed   ......  It looks like the amd64 and i386 versions didn't match.  Installing ia32-libs and ia32-libx-multiarch I got the same problem, since it asked for libc:i386.  I have no idea how to go on.  Please help me.  Thank you very much.


Are Tommen and Myrcella Lannister also bastards?

Are Tommen Lannister and Myrcella Lannister offspring from the (incestuous) relationship of Jaime and Cersei Lannister as well?


Mount USB drive with write permissions for everyone or specific user

I know there are similar questions but I get some specific problem I can't overcome.  I have:   HDD split into two partitions. /dev/sdb1 and /dev/sdb2.  sdb1 is NTFS and I don't need it. I need sdb2 which is fat32. Ubuntu 12.04.1 LTS (server)   I want:  Ultimately I need a perma-mount /dev/sdb2 to /home/storage with access right (rw) for the user media.  Problems I'm facing:  1) Using manual mount from command line.  If I just use  server# sudo mount /dev/sdb2 /home/storage   It mounts but the /home/storage receives root as owner and group and doesn't allow media user to write there.  If i use mount command without sudo as the user media - i'm not allowed. Says only root can use mount.  If I use mount with options: server# sudo mount /dev/sdb2 /home/storage -o umask=000 I get what I need. A bit overdone of course, since the storage folder becomes writable for everyone. BUT - that is manually mounted - now i need it to remount on every reboot.  2) Remounting on reboot - using fstab  So I thought I'll be fine if I use fstab to mount this partition (/dev/sdb2) every time i reboot. The fstab line I added:  UUID=8C52-C1CD /home/storage auto   user,umask=000,utf8,noauto  0   0  got uuid with blkid. The fs type auto i changed few times...tried vfat too, but always on the reboot ubuntu stops when processing fstab (as i think) with the message (took from the log):  fsck from util-linux 2.20.1 /dev/sda5: clean, 120559/10969088 files, 19960144/43861504 blocks mount: unknown filesystem type 'static' mountall: mount /etc/fstab: [772] terminated with status 32 mountall: Filesystem could not be mounted: /etc/fstab: Skipping /etc/fstab: at user request  And also - sudo mount -a never really does anything.  What am I doing wrong? I do suspect I messed up something:)  UPDATE:  As it seems - fstab should hold only mounts for static drives, not any sort of usb stuff. I'm puzzled how then this works with all the people posting on the net their success stories...  however..if this is not possible - i would like to know how to remount my usb after every reboot...if not with fstab - than how?:)


$\frac{\partial f_i}{x_j}=\frac{\partial f_j}{x_i}\implies(f_1,\ldots,f_n)$ is a gradient

I was reading a solution when I came across this statement.     So $$\frac{\partial f_i}{x_j}=\frac{\partial f_j}{x_i}.$$ Then there exists a differentiable function $g$ on $\mathbb{R}^n$ such that $\frac{\partial g}{\partial x_i}=f_i$.   Why is this true?


I am travelling to Durban on 21.10.2017. I will be reaching Dubai at 22:00 at Terminal 1 and my next flight to Durban is at 10:45 the next day from Terminal 3. This means I will have to remain at Dubai Airport for 12 hours 45 minutes in total.  As the layover time is quite long, do I need to have a transit visa if I stay within the airport terminals and does not come out?


I'm trying to install Wine, but Synaptic shows that the package is broken. I tried installing it using the terminal, but it shows this: The following packages have unmet dependencies:  winehq-stable : Depends: wine-stable (= 6.0.0~focal-1) E: Unable to correct problems, you have held broken packages.  I tried running these commands: sudo apt-add-repository --remove 'deb https://dl.winehq.org/wine-builds/ubuntu/ cosmic main' sudo apt update sudo apt-add-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ bionic main' sudo apt update sudo apt install --install-recommends winehq-stable  but they didn't fix the problem. What can I do?


Ubuntu 12.04 Server - MySQL keeps crashing - Possible InnoDB problems

I have been searching for a solution but nothing seems to work.  I have a single Drupal 6 website up on this server.    Server:Ubuntu 12.04 Apache/2.2.22 (Ubuntu) 5.3.10-1ubuntu3.8 MySQL 5.5.32 Drupal 6  Here is a link to my Apache2 and MySQL error files and my config file for MySQL.  Please have a look.  Those files are huge, that is why I linked to them instead of pasted them in here.  If I need to I can paste in here.  Just let me know.  Thanks.  I have done a lot of searching.  I mostly try to Google the errors themselves but can't seem to find the right solution.  I think I have narrowed it down to a problem with innodb but that is it.  I check the tables in the error log and phpMyAdmin say they are ok and I repair them anyway and still get the crashing.  When my site crashes, I have to restart Apache and then restart MySQL and then the site comes back up.  It has been crashing 2 - 6 times a day.  Any help would be greatly appreciated.  Thanks.


Can I resume levelling up as a paladin after taking a few levels as an Oracle?

I want to do a build that is Paladin and Oracle, but I can't seem to find any concrete information on going about this. If I start at Paladin, get to level 2, then level Oracle to 4, can I then continue getting levels in Paladin at total level 7, or can I not go back to previous classes?  One friend has told me you cannot do that, but I can't find anything online about it. We are playing Pathfinder and this is a new half-elf character starting at level 4, so I'm not invested in it yet.


Is there exist a function defined on the real or complex numbers that, restricted to the integers, is equal to the factorial?

The title already contains the question, Basically I am wondering if it is possible to naturally define a function, continuous and differentiable, such that when restricted to the integers it is equal to the factorial.


Recommendation on ADM mass and Bondi mass

I want to learn some advanced topics in GR, such as . However nearly no textbooks on GR contain this area, such as Wald, MTW, Hawking, Carroll and  Zee's. Can anyone recommend some textbooks or papers giving the elaboration in detail?


How did humans end up in space if Star Wars is set in the past?

I’m of the understanding that the canon Star Wars movies are set in the relative past (18th and 19th century in our time). Yet looking up the biographies of characters like Padmé Amidala, Obi-Wan Kenobi, Anakin Skywalker etc their species is listed as ‘human’.  If they are indeed, human beings as you and I, how did they manage to end up in the far reaches of space hundreds of years ago, when we don’t have to technology to travel long distances in space even today?


Reed–Muller codes are a family of linear error-correcting codes used in communications. The code of $RM(2,3)$ could be generated with matrix: \begin{pmatrix} 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ 1 & 0 & 1 & 0 & 1 & 0 & 1 & 0 \\ 1 & 1 & 0 & 0 & 1 & 1 & 0 & 0 \\ 1 & 1 & 1 & 1 & 0 & 0 & 0 & 0 \\ 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 \\ 1 & 0 & 1 & 0 & 0 & 0 & 0 & 0 \\ 1 & 1 & 0 & 0 & 0 & 0 & 0 & 0 \\ \end{pmatrix} In several sources I have read there is a way to build systematic Reed-Muller code which keeps recieved signal of length $n$ in first $n$ bits of output signal. But I couldn't find how to do it.   Any ideas?


"Too many open files" - how can I set the ulimit -n value for emacs on Lion?

I've seen other questions covering the topic of how to set the file limit on Leopard/Lion.  For example:            But after  reading through those I'm still not clear on how I would set the open file limit for my instance of emacs.  Can anyone explain that to me?   It seems to me that ulimit -n sets the limit for the current shell.  That won't work for emacs, because emacs is not a shell. Also, apparently launching emacs from the shell would allow the ulimit -n value for the shell to apply to emacs. But I would like to not invoke emacs from a  shell; I'd like to just click the pretty icon.   Also there are some other ways to modify the open file limit but I am not clear  on exactly where those limits apply. At least one of the limits applies to "all open files on the operating system" and for my purposes that is much too broad a brush.   I want to know how to set the file limit for a specific app.  Chrome, Emacs, or whatever. In my particular case, I am interested in emacs but I guess it would be a generic solution.   Thanks.  [I tried tagging this with ulimit but could not, because I am at 101 rep right now]


What does the contraction ain't mean? Is it appropriate to use it in formal settings?


Application of orbits and Sylow Theorems

Suppose I have a group $G$ such that $n_p \not \equiv 1 \pmod{p^2}$, where $n_p = |\operatorname{Syl}_p(G)|$. Consider a $P \in \operatorname{Syl}_p(G)$ acting on $ \operatorname{Syl}_p(G)$ by conjugation. I want to show that $\exists Q \in \operatorname{Syl}_p(G) : |\mathcal{O} (Q)| = p$. I was considering how to apply the orbit-stabilizer theorem, but I do not know how to apply the fact that $n_p \not \equiv 1 \pmod{p^2}$.


How can a body have two axis of rotation at the same time?

I m not concerned with rotation of a body with two simultaneous axis but concerned with how we choose the axis,while going through pure rolling I have observed that there are two axis of rotation one is passing through the center of mass and the other is through the point in contact with the ground,my concern is how can there be any axis of rotation through the point of contact where as m very well finding the body does not rotate in that axis of rotation that is it very well rotates only through the center of mass.


I am creating the image of the PowerPoint file programmatically. And after saving the Images to the local drive I am getting the files using DirectoryInfo.GetFiles(). I am saving the image files with the sequence numbers.     My Files:   My issue is when I get the files, are not in the sequence I need them in. The files sequence which I am getting in the FileInfo[] is :    Can any one help me to solve this issue?


How to determine which lightdm greeter is in use?

For those who don't know, greeter is basically the login screen. In case of Lightdm specifically, there are several versions of it:   unity-greeter kylin-greeter lightdm-gtk-greeter lightdm-kde-greeter lightdm-webkit-greeter razorqt-lightdm-greeter   The goal:  I need to know how to obtain the greeter version currently in use. Scripting solutions are most welcome ( preferably python, shell scripts, perl ) but also open to C code. Ideally , the solution would work like so:  $ ./get_greeter kylin-greeter   Issues and failed approaches:   Checking process listing doesn't work. I have kylin-greeter in use right now, but pgrep -f lightdm | xargs -L 1 ps -o args --no-header -p or  pgrep -f kylin | xargs -L 1 ps -o args --no-header -p return nothing that points to /usr/sbin/kylin-greeter  lsof -p <LIGHTDM_PID> also provides no insights - no /usr/sbin/kylin-greeter among the listing. Parsing /etc/lightdm/lightdm.conf is a potential, but not ideal solution, since some flavors of Ubuntu ( such as Kylin ) won't explicitly state greeter session in that file.  I would prefer something more reliable. gsettings doesn't provide a reliable means of determining greeter in use either - presence of schemas for unity-greeter doesn't mean I am currently using that. examining paths and methods on org.freedesktop.DisplayManager service for system bus provided no insights into what greeter is in use either.


python 3.6, for input() - achieve time out and skip to next line

Newbie to python.  I looked around the web and found raw_input() had some workaround to achieve timeout. But in 3.6 there is no raw_input()   name1 = str(input("please enter name of preferred student 1: "))  name2 = str(input("please enter name of preferred student 2: "))   I want user to enter input for first line in 5 secs, if he dint enter any input i want my code to skip for second line of code.


How to pin programs to the left part of the Start menu?

I want to pin programs to the left part of the Start menu, under the username, the same way as it worked in Windows 7. The area is completely empty (normally it would house the most used programs, but I have disabled that functionality). Using the "Pin to Start menu" context menu option results in a new tile being created in the right part of the start menu (the Metro ghetto). Dragging from within the Start menu or from Explorer to the left area of the Start menu only results in a no symbol icon appearing. The articles I've read (no doubt written at some point during the preview) indicate that dragging should work, but empirical evidence disagrees.


Factorials, Simplify the addition and multiplication of factorials.

I have an equation containing factorials  here  $$(k+1)!+(k+1)(k+1)!$$  yet I am having a hard time understanding how to simplify it using algebra. A simple search on wolfram gets me a reduced form of   $$(k + 2)! $$  This would be a great refresher to such problems, sadly I don't know the elementary operations to reduce it.


Equivalence relation $(a,b) R (c,d) \Leftrightarrow a + d = b + c$

Suppose $A$ is the set composed of all ordered pairs of positive integers. Let $R$ be the relation defined on $A$ where $(a,b) R (c,d)$ means that $a + d = b + c$.  (a) Prove that $R$ is an equivalence relation.  Here is what I have so far. Is this correct?  Reflexive: $a \sim a$ $\implies$ $a+b=a+b$; $(a,b) R (c,d)$  Symmetric: if $a \sim b$ then $b \sim a$ $\implies$ if $a+d=b+c$ then $c+b=d+a$  Transitive: if $a \sim b$ and $b \sim c$ then $a \sim c$ $\implies$ if $a+d=b+c$ and $c+f=d+e$ then $a+d=d+e$  (b) Find $[(1,1)]$.  I'm not sure how to approach this.


Installing latest version of Python on Ubuntu 14.04 LTS without building from source

I am looking for a reliable choice.  How to install Python 3.4.3 on Ubuntu 14.04 LTS without building from source?


How do I apply 1ed/2ed magic resistance to D&D 5e in a conversion

In earlier editions of D&D some powerful creatures had a percentage magic resistance which was checked before any saving throw (if applicable). If the percentage check was successful then the spell simply didn't work.  I'm trying to convert the Dragonlance Draconians to 5e, but they had 20% magic resistance (and per the source materials this prevented Raistlin's sleep spell working on them).  Simply giving them advantage on saving throws won't work on magical effects without saving throws such as sleep, and ignoring the magic resistance completely in the conversion will significantly weaken the main antagonists (apart from dragons) in the Dragonlance Campaign.


I'm having trouble creating a header with boxes, images and other features. Is it possible to create a header like the following one in LaTeX? How?


sizeof(myobject) not what I have calculated

So, I'm a bit confused. I need to be able to create many (up to a billion) small (<8 elements) fixed-sized arrays at runtime. I was using std::vector, but the memory overhead was too high (24 bytes per array).   I decided to implement my own array, templated on the contained type (T1) and the type storing the static size of the array (T2).  The class is called lw_vector. If I call:  sizeof(lw_vector<int, unsigned char>)    I get 16. However, as I calculate it, the size should be sizeof(int*)+sizeof(unsigned char)=9 on a 64-bit system. What am I doing wrong here? Is it possible to create an object that only requires 9 bytes of memory?  Here's the implementation of lw_vector:  template<class T1, class T2> class lw_vector { private: public:     T2 N;     T1 * content;      lw_vector() : N(0)     {}      lw_vector(T2 Nt) : N(Nt)     {         content = new T1[N];     }      ~lw_vector()     {         delete[] content;     }      lw_vector& operator=(lw_vector temp)     {         std::swap(N, temp.N);         std::swap(content, temp.content);         return *this;     }      lw_vector(const lw_vector& other)         : N(other.N),         content(new T1[other.N])     {         std::copy(other.content, other.content + N, content);     }      inline T1& operator[](T2 ind) const     {         return content[ind];     } };   Thank you for your time!  John


How does the vulnerability from the Tomb of Levistus warlock invocation interact with the resistance from the tiefling's Infernal Legacy trait?

The description of the warlock's  eldritch invocation says (Xanathar's Guide to Everything, p. 57; emphasis mine):     As a reaction when you take damage, you can entomb yourself in ice,   which melts away at the end of your next turn. You gain 10 temporary   hit points per warlock level, which takes as much of the triggering   damage as possible. Immediately after you take the damage, you gain   vulnerability to fire damage, your speed is reduced to 0, and you are   incapacitated. These effects, including any remaining temporary hit   points, all end when the ice melts.   The 's Infernal Legacy racial trait grants fire resistance.  For a tiefling warlock with the Tomb of Levistus invocation, how would this eldritch invocation (specific) interact with this racial feat (general)?   Do they cancel? Or does the magic of the Tomb of Levistus invocation (specific) overpower the Infernal Legacy trait (general) completely?   Which applies here? General vs. specific rules, or resistance vs. vulnerability rules?


is there any way to export and import nodes programmatically...? While import if the node already exists then it should be updated without creating a new node.


I tried by using $t^2$ = $tan\theta$ and then by inserting $t^4$ by $tan^2\theta$ in $\int_{0}^{1} \sqrt[]{1+t^4}dt$, I get $dt$ = $\frac{sec^2\theta\times d\theta}{2\times \sqrt[]{tan\theta}}$ &  $\sqrt[]{1+t^4}$ = $sec\theta$. Thus the integration becomes $\int_{0}^{\frac{\pi}{4}} \frac{sec^3 \theta \times d\theta}{2\times \sqrt{tan\theta}}$ What to do after this step? I have tried to do this which I have mistakenly written in the answer column. \begin{align} \int_{0}^{1}\sqrt{1+t^4}\,\mathrm{d}t &=\int_{0}^{1}\frac{1+t^4}{\sqrt{1+t^4}}\,\mathrm{d}t\\ &=\int_{0}^{1}\frac{\mathrm{d}t}{\sqrt{1+t^4}}+\int_{0}^{1}\frac{t^4}{\sqrt{1+t^4}}\,\mathrm{d}t\\ &=\int_{0}^{1}\frac{\mathrm{d}t}{\sqrt{1+t^4}}+\int_{0}^{1}t\cdot\frac{t^3}{\sqrt{1+t^4}}\,\mathrm{d}t\\ &=\int_{0}^{1}\frac{\mathrm{d}t}{\sqrt{1+t^4}}+\left[\frac12t\sqrt{1+t^4}\right]_{0}^{1}-\frac12\int_{0}^{1}\sqrt{1+t^4}\,\mathrm{d}t\\ &=\int_{0}^{1}\frac{\mathrm{d}x}{\sqrt{1+x^4}}+\frac121\sqrt{1+1^4}-\frac12\int_{0}^{1}\sqrt{1+t^4}\,\mathrm{d}t\\ \implies \frac32\int_{0}^{1}\sqrt{1+t^4}\,\mathrm{d}t &=\frac{1}{2}\sqrt{1+1^4}+\int_{0}^{1}\frac{\mathrm{d}t}{\sqrt{1+t^4}}\\ \implies \int_{0}^{1}\sqrt{1+t^4}\,\mathrm{d}t &=\frac{1}{3}\sqrt{1+1^4}+\frac23\int_{0}^{1}\frac{\mathrm{d}t}{\sqrt{1+t^4}}.\\ \end{align}


Show that if $a^{n-1} \equiv 1 \pmod{n}$ for all $a$ such that $\gcd(n,a) = 1$, then $a^{n} \equiv a \pmod{n}$ for all $a$.

In Burton's Elementary Number Theory, when introducing absolute pseudoprimes (also called Carmichael numbers), the author states that they are composite numbers $n$ such that $a^{n-1} \equiv 1 \pmod n$ for all integers $a$ with $\gcd(a,n) = 1$.   When showing that 561 is an absolute pseudoprime, he then concludes that $a^{561} \equiv a \pmod{561}$ for all $a$.   I searched a bit on the internet, and it seems that these two are actually equivalent definitions of a Carmichael number. However I have not been able to find a proof; the fact that the implication in the title of the post is stated so plainly in my textbook makes me think it is quite simple to see, but I can't seem to understand the argument.


Manually run a cron job / simulate running cron job?

I want to test if cron's mailing stuff after an executed task and things like that work. Is there a more elegant way to test this, then setting a cron job to run every few seconds? So, is there any way to simulate the execution of a cron job / start a cron job manually, but with the same behaviour it would have when being run automatically by cron?


Books about alternative interpretations of quantum mechanics

Recently I've heard that there exist alternative interpretations of quantum mechanics which, while not as widespread as the Copenhagen intepretation (or so it would seem), are equally valid in the sense that they describe all the observable effects.  mentions a few ones, the more popular of which seems to be the many worlds interpretation.  What are some books, suitable for someone with an undergraduate level knowledge of QM, that describe these alternatives? Something not too mathematical might be best for an introduction to the subject, but I'm not looking for a popular book either, of course.


Identify the universal property of kernels

I'm reading Mac Lane's "Categories for the Working Mathematician". I found the following sentence in page 59 of it:     Similarly, the kernel of a homomorphism (in $\mathbf{Ab}$, $\mathbf{Grp}$, $\mathbf{Rng}$, $R$-$\mathbf{Mod}$, . . .) is a universal, more exactly, a universal for a suitable contravariant functor.   I know how to express a quotient by a universal property in a category. But I really have trouble understanding how to express the kernel of a homomorphism as having a universal property.


I need to add a p7b root ca to Ubuntu, in order to connect to services/servers for my company.  Based on what I have found on the internet, it seems that I need to convert this file to either .crt or .cer. I used the following commands to convert the file:  openssl pkcs7 -inform der -in cert.p7b -out cert.cer openssl pkcs7 -inform der -in cert.p7b -out cert.crt   I then moved these files (I actually tried them one at a time) into /usr/share/ca-certificates/mycompany, and then added mycompany/cert.cer and mycompany/cert.crt to the /etc/ca-certificates.conf. After performing update-ca-certificates I still get root CA warning that the certificates/chain isn't in the system.   The only direction my company has given is for both Windows and adding this file into the OSX keychain. Any help is appreciated, because I don't like disabling https while using remote services/tools for my company.


Are Lockheed Martin nuclear fusion claims realistic?

Lockheed Martin reported breakthroughs on nuclear fusion technology for energy. Are these claims scientifically realistic?  The claims have been reported in the media:


Can I transfer my characters and The Taken King from Xbox 360 to Xbox One?

I got Destiny on Xbox 360 and Xbox One. I was wondering if I can transfer my Xbox 360 characters to Xbox One. I don't have The Taken King on Xbox 360 but I do on Xbox One. If I transfer my characters, will I still have The Taken King?


Are ISPs able to track individual devices connected to a personal router?

Quick question about how ISPs and personal routers. So, I have a personal router and have about 13 devices currently connected to the router. Is there anyway that my ISP would know how many devices are currently connected to the line via my personal router? Basically, if I used my personal router, what kind of information does the ISP have access to?


Is leaving the US for a couple of days enough to get another 3 months in the country?

I hope someone can help me.  I am currently on holiday for 3 months in America under the Visa Waiver Program and would like to stay an extra 2 or 3 weeks. I know I will have to leave the country, renew my visa waiver and then reenter and so wanted to know if I will have an issue reentering.  I will only be out of the country for about 24 to 48 hours, just enough to renew the visa and get on a plane. I understand it is up to the border control person on the day, but does anyone think I will have an issue??


Significance of $i$ in the Schrödinger equation

There's an imaginary $i$ in the Schrödinger equation, which I guess is to define the position of the particle in a space-time involving a complex function. But what is the real physical significance of $i$ in the equation?


Is there a command-line tool for converting html files to pdf?

I would like to install a command line tool within a Docker image in order to quickly convert *html files into *pdf files.   I am surprised there is not a Unix tool to do something like this.


How to detect idle time in JavaScript elegantly

Is it possible to detect "idle" time in JavaScript? My primary use case probably would be to pre-fetch or preload content. Idle time: Period of user inactivity or without any CPU usage


How to reproject WSF layer created from GeoJSON?

I have a WFS layer:  myVecLayer_disp= new OpenLayers.Layer.Vector("Редактируемый участок",{projection: new OpenLayers.Projection("EPSG:900913")});   And i have feature store:          var protocol=new OpenLayers.Protocol.HTTP({             url: url_servlet+"fullSearch.jsp",             format: new OpenLayers.Format.GeoJSON({internalProjection: new OpenLayers.Projection("EPSG:4326"),externalProjection:new OpenLayers.Projection("EPSG:900913")})     });     searchStore = new GeoExt.data.FeatureStore({         layer: myVecLayer_disp,         fields: [             {name: 'id', type: 'String'},             {name: 'name_dispatcher', type: 'String'},             {name: 'voltage', type: 'String'},         ],         proxy: new GeoExt.data.ProtocolProxy({             protocol: protocol,         }),         autoLoad: true,         layerOptions: function() {             return {                 strategies: [new OpenLayers.Strategy.BBOX()],                 //projection:"EPSG:4326"             };         }     });   As you see i use GeoJSON. In this geojson i have features in wgs84. And reproject it in mercator in protocol. Now i show this layer:      app.mapPanel.map.addLayers(myVecLayer_disp); myVecLayer_disp.visibility=true;   And see features near Africa but expect to see it within Russia. So Nothig reproject i think. But when i see layes's features:      LINESTRING(0.00055807640304122 0.00050642147755534,0.00055807616948463  0.00050641930362077,0.00055807588202664 0.00050641664462617,0.00055807423809849  0.00050641332981391,0.00055807306129967 0.00050640979946183,0.00055807191147579  0.00050640644872202,0.00055807052802261 0.00050640231648177,0.00055806910873212  0.00050639813934481,0.00055806841697321 0.00050639609116937,0.00055806763547558  0.00050639388128181)   Ant this is same feature in geojson:  {"type":"LineString","coordinates":[[62.124781001642077,56.374581001212391], [62.124755002241727,56.374338999945053],[62.124723002564679,56.374043002482722], [62.124540001320156,56.373673997157425],[62.12440900067503,56.373281000617851], [62.124281002866155,56.37290799870533],[62.124126997563053,56.372447999975407], [62.123969002867341,56.371983002813522],[62.123891996618511,56.371755002191776], [62.123805000700372,56.371508997142655]]}   What i doing wrong?


Does this Eldritch Knight using Polearm (Glaive) build work?

EDIT: Thank you for all the links you provided answering the first part of the post, regarding the stacking of Polearm Master (PAM), War Caster (WC) work and Spell Sniper (SS) feats. [if someone didn't know, the consensus is that combining the three will allow you to cast booming blade in place of an opportunity attack when an enemy enters or exits your reach of 10 ft]  I would be grateful if someone could help with the second part regarding the damage output. From a damage point of view, using the cantrips as the main source of damage, I will not allow me to use the PAM bonus attack. That is until level 7 when I use the cantrips until Level 7 where EK gets War Magic     Beginning at 7th level, when you use your action to cast a cantrip, you can make one weapon attack as a bonus action.   However, I will also be losing the Extra Attack feature since I will not be able to attack twice when using a cantrip. Then scaling past level 10, I will lose even more Extra Attacks.  My questions are:  a) Is that how Extra Attack and War Magic interact? In that regard, is it worth becoming an Eldritch Knight?  b) Other than thematically, does it make sense in terms of damage to use 3 feats for what appears to be a less than synergistic character, between normal attacks, cantrip attacks and extra attacks?   c) Should the natural progression be level 1 PAM, level 4 SS and then level 6 WC?  Again, thank you for taking the time to read this and reply!


Using Files on the Internet Automatically?

Suppose I want to tabulate file  as follows. \documentclass{article} \usepackage{csvsimple,longtable} \begin{document} %https://fred.stlouisfed.org/graph/fredgraph.csv?id=WILL5000INDFC \csvautolongtable{WILL5000INDFC.csv} \end{document}  Can I read it remotely during compiling? Or can I automatically download and include it during compiling?


Permission denied error when writing to file

Receiving permission denied error when writing to the file.  Any help is appreciated. Thank you


What's the relation between complex and vectors......Complex are usually represented as position vectors and during rotation we only rotate the directed line formed by the two complex.Why do they share some properties when they are entirely different?


Can't seem to understand what is the problem here. i have this error message Exception in thread "main" java.lang.NullPointerException

i'm having this problem and been stucked on this for hours. Im fairly new here and hope you guys are able to assist. I thought the problem was with declaring the array or something but i cant seem to fix it. My idea was to split the codes into three different parts to construct, display and the main method but apparently along the way there was an error. private static void constructArray(Customer [] c){     c = new Customer[3];     ArrayList<ItemInfo> cust1 = new ArrayList<>();     cust1.add(new ItemInfo("Mutton", 1, 19.85));     cust1.add(new ItemInfo("Stationery",2,17.66));          ArrayList<ItemInfo> cust2 = new ArrayList<>();     cust2.add(new ItemInfo("Fishball",1,12.07));     cust2.add(new ItemInfo("T Bone Steak",3, 19.20));     cust2.add(new ItemInfo("Stationery", 2, 12.25));          ArrayList<ItemInfo> cust3 = new ArrayList<>();     cust3.add(new ItemInfo("Crab", 2, 14.08));          c[0] = new Customer(cust1, "cheque");     c[1] = new Customer(cust2, "cash");     c[2] = new CustomerPlus(cust3, "Paynow", true); }  private static void displayArray(Customer [] c){      c = new Customer[3];      for(Customer cust : c){         if(cust instanceof CustomerPlus){             CustomerPlus plus = (CustomerPlus) cust;             plus.addItem(new ItemInfo("Cigarette",2,12.96));             System.out.printf("Mode of payment:%s%nInvoice no:%04d%n%n", plus.getPaymentmode(), plus.getNumber());             System.out.printf("%s%19s%10s%13s%n","Item","Quantity","Price","Sub Total");             System.out.println(plus);             System.out.printf("Total payment: %.2f%n", plus.computePayment());             if(plus.getAdult())                System.out.println("Customer: adult");             System.out.println("-----------------------------------------");                         }          else{            System.out.printf("Mode of payment:%s%nInvoice no:%04d%n%n", cust.getPaymentmode(), cust.getNumber());            System.out.printf("%s%19s%10s%13s%n","Item","Quantity","Price","Sub Total");            System.out.println(cust);            System.out.printf("Total payment: %.2f%n", cust.computePayment());            System.out.println("-----------------------------------------");         }     }  }   public static void main(String[] args){     main m = new main();     Customer [] c = new Customer[3];     constructArray(c);     displayArray(c);               }


Installation of Remastersys in Ubuntu 16.04

I am using Ubuntu 16.04lts and want to install Remastersys. Pl. show me the answer who is using it.


An inequality from Littlewood's Miscellany

Why is the following inequality from Chapter 1 of Littlewood's  true?      Suppose $a_n>0$ for all $n$. Then $$\limsup_{n\to\infty}\left(\frac{1+a_{n+1}}{a_n}\right)^n\geq e.$$


Page numbers in a PDF are off, how can I change them?

I have a digital edition of textbook I bought. The pages are numbered from 1 - 570.  As a result, when I search page 68, it shows page 51 as the first pages originally in the textbook aren't numbered and there's a whole index of some numbered as XVII.  What can I do to edit this textbook, or change the page numbers accordingly?


Does multivariate multiple regression take into account correlated outcomes?

Thank you so much for your time. I am running an analysis where I explore the association of the same predictors across multiple outcomes (these outcomes are correlated). My understanding is that when I run this in R: lm.all <- lm(cbind(outcome1, outcome2, outcome3) ~ age + sex + education, data = df) That when using summary(lm.all) the output is the same as running multiple univariate regressions (so per each outcome). How do I take into account the correlations between my outcomes?


How to find sum of this series $\sum_{0}^{\infty} \frac{(n!)^{2}x^{n}}{(2n)!}$

Actually I have no idea how to begin. I tried to represent it as a product of two series or as a sum of two series but have no result with this. Any idea ?


Are there other undocumented paths apart from timeline and reputation audit?

I'm aware of these interesting (relative) paths that can be used on any SE site:   The timeline of a post, such as . It has a relative path like /posts/postid/timeline (similar to the path of the revision history of a post, in which the revisions-part of it is changed to timeline). The reputation audit on a site, such as . It has a relative path like /reputation.   To my knowledge:   nowhere in the help pages these relative paths are documented. there is not even 1 page on any SE site that have a link to any of these relative paths.   I only discovered these (what I call) undocumented relative paths by accident, after I saw them mentioned in some post.  Question: are there any other undocumented relative paths, and available to anybody (so not just mods or so)? If so which ones, and what is their purpose?


Can the power button of a PC or laptop be remapped?

Forget for a second how bad an idea this would be. But is it possible to remap the power button of a PC or laptop to, say, print some message or anything other than managing the power?  If not, why? Who handles that button, and how low-level such a modification would have to be?  I'm also interested in how the answer changes in the various systems, if it does.


Let p and q are odd prime numbers such that q=2p+1. Prove that   i) $-4$ is primitive root modulo $q$.  ii) If $p  \equiv  1 \pmod 4$ then $2$ is a primitive root mod $q$.   iii) If $p  \equiv  -1 \pmod 4$ then $-2$ is a primitive root mod $q$.


How can I determine the point of X on the map, or the distance between X and either end point.  The dashed line from X to point is perpendicular. The distance between each point is on the map, and the points would be approx:  var a = {latitude:48, longitude:-90}; var b = {latitude:49, longitude:-92} var c = {latitude:48.25, longitude:-91.8};   Map image:


How do I prepare a scanned pencil sketch for coloring in Photoshop?

I want to color sketches in Photoshop, but when I prepared the sketch (using Levels, Hue, and other modifications) to turn it into workable line art, some details were missing. I think it depends on how you draw your sketch.  What are important steps for drawing a sketch (with pen or pencil) that is to be colored in Photoshop? A step-by-step instruction would be appreciated.  For instance, here it is the sketch    This is after my preparations in Photoshop


strange network issue after new router 'unkownXX…' terminal promt instead of Name

Some weeks ago I got a new router* and since then I encounter some local network issues from time to time (at the moment I can’t reproduce when this happens):   Wifi is connected but webpages don’t load. The page stays blank and I get no message about a missing network connection. Accessing tobis-mac.local (or http://localhost, or http://127.0.0.1) is really slow or don’t load at all (same as 1). When I disable wifi (i.e. no network connection for my mac) the local host again is as fast as usual. While this happens The terminal promo reads  unkown7cd1XXXXXXXXX:~ Tobi$   (I replaced some digits with X because I have no idea if this info should be kept private …) instead of the normal  Tobis-Mac:~ Tobi$    Some setup information   I’m using a MacBook Pro mid 2012 13" running OS X 10.11.4 (I made the update today. The described error occurred under 10.11.3, though). My Mac is connected via Wifi; Wifi uses 2.4 GHz only and WPA (no WPS) The router is the one I got from my provider, which is o2 Germany: o2 HomeBox 6641. ZyXEL Communications Corp.   I’m aware that my descriptions are rather incomplete but I am far from being an network expert so let me know if I can provide further information ;-)


I'm gonna compile Rodinia benchmark on Gem5-gpu simulator, when I make it complains for gcc-4.4 and give me following error:  make gem5-fusion make -f Makefile.gem5-fusion make[1]: Entering directory '/home/hodjat91/Desktop/gem5-gpu/benchmarks/rodinia/backprop' gcc-4.4 -DOUTPUT -O3 -I../../../gem5/util/m5 -I../../libcuda  -I/usr/local/cuda//include -I/home/hodjat91/NVIDIA_GPU_Computing_SDK/C/common/inc/ -L/home/hodjat91/NVIDIA_GPU_Computing_SDK/C/lib -g -c facetrain.c -o facetrain.c_o make[1]: gcc-4.4: Command not found ../common/common.mk:139: recipe for target 'facetrain.c_o' failed make[1]: *** [facetrain.c_o] Error 127 make[1]: Leaving directory '/home/hodjat91/Desktop/gem5-gpu/benchmarks/rodinia/backprop' Makefile:8: recipe for target 'gem5-fusion' failed make: *** [gem5-fusion] Error 2   I have gcc 5.3 on my system.  Thanks


How to automatically eliminate white space around a figure?

I am creating figures in Powerpoint to be included as PDF files in my LaTeX document. I know one can use a combination of trim and clip to eliminate the white space around a figure. But this requires the specification of the amount of white space around the figure (measurements for trim). Is there a way to just crop the image automatically so that it is only as large as the bounding box for the contents


Let $S$ be an equilateral triangle, and $f$ is a continuous function such that for any point $O$ inside $S$, with distances $x,y,z$ from vertices of $S$, $f(x)+f(y)+f(z)=0$. Prove that $f$ is identically zero.


Why can't we use wildcard character * in a soql as we can use in sql ?

I got the answer "Salesforce is a multitenent environment and performing such query including wildcard can affect other tenants" but I do not understand how other tenants will be affected by this Query.Most of the limitations in salesforce like limit in soql queries and No. of Dml in one context is limited and the reason is shared Environment(Multitenant).I actually want to know how one tenant can affect other tenant ?


Anime creature with many trumpets on its side. Mid 80's

I remember this mid 80's cartoon movie, I think anime.  A human child is nurtured by two fictional animal like creatures, perhaps on a spaceship. I remember one of them having funny trumpet-like organs on his sides. Maybe a phoenix is also involved in the plot?   I think the child had white complexion. The creature with trumpets appears purple in my memories. The scene that hit me was this creature making music with these many holes on his side to cheer up the baby. One of the creatures might have resembled a dinosaur...


I'm trying to query for records that do not contain LTD or LLP in the name and are also not assigned to a certain record type. I have tried just about every variation with parenthesis and AND/OR conditions but jo joy. Can anyone help? Fields removed for simplicity.   SELECT Full_Name__c, Account.Name FROM CONTACT   WHERE   NOT(account.name LIKE '%LTD%' OR account.name LIKE '%LLP%')   AND  (RecordType.Name != 'Broker' OR account.RecordType.Name != 'Broker')  ORDER BY account.name   Note that the below query does work:   SELECT Full_Name__c, Account.Name FROM CONTACT   WHERE   NOT(account.name LIKE '%LTD%' OR account.name LIKE '%LLP%')   ORDER BY account.name


What makes Thanos the most powerful being in the universe?

In Guardians of the Galaxy, when Ronan got stone of infinity on Knowhere and decided to not give the stone to Thanos, Korath told him that Thanos is the most powerful being in the universe. Why is he so powerful? His only abilities so far I can see are achieved using the stones in Avengers. His only visible power is strength, but without stones he would not have chance even against most Avengers in 1v1 fight.  I didn't read any Marvel comics, I've just seen the films, so are there any abilities he doesn't use in the films? Or why is he considered the most powerful being if he seems so weak without the stones (compared to Avengers, for example)?


Collapsible (conditional, loop) blocks in Visual Studio 2012 (C#)

There doesn't seem to be a solution to this so far, other than using region directives, which add on unnecessary work.  There are plugins, but all are for 2010 or below.  It would be great if you could collapse/expand conditional and loop blocks.  Anybody know of a newer plugin for VS 2012 that does this?  This function already exists for the C++ text editor, but it doesn't carry over when you're in the C# editor.


Taking ownership of comments on migrated questions

When a question is migrated to a SE site that I'm not registered to, I can't claim ownership of my comments. An example question:   I registered only after the question was migrated and can't delete my comments. I always like to perform some garbage collection of noise comments made by me. (like on the example question)  Would it be possible to claim ownership of comments in this scenario? Is this a bug?


Are there nontrivial equations for hyperoperations above exponentiation?

A similar question was asked in .  A paper by Roberto Di Cosmo and Thomas Dufour () asserts in footnote 2 (p.3) that it has been shown "that there are no nontrivial equations for $⟨\mathbb{N}, \mathrm{Ack}(n, \_, \_)⟩$ if $n > 2.$" References make it clear that $\mathrm{Ack}(n,x,y)=H_{n+1}(x,y)$ in the , so the assertion is as follows:     $\text{There are no nontrivial equations for the binary function }(\_\uparrow^y\_)\text{ if }y>1\\ \text{ (i.e., for hyperoperations above exponentiation)}\tag{*}.$   (For this, the above paper cites Charles F. Martin, "Axiomatic bases for equational theories of natural numbers", Notices of the Am. Math. Soc., 19(7):778, 1972, which I have not found online.)  Q.1: What, precisely, is meant by a "nontrivial equation" here?  (The defining recursion $$x\uparrow^{y+1}(z+1)=x\uparrow^y (x\uparrow^{y+1}z),$$ which certainly holds for $y>1$, is evidently considered trivial.)  Q.2: Is the following a valid proof based on assertion $(*)$? ...  Claim:     If $x,y,z$ are integers $\gt 1$, then the value of $\ x\uparrow^y z\ $ uniquely determines $x,y,z$; i.e.,  $$x\uparrow^y z = x'\uparrow^{y'} z' \quad\implies\quad x=x',\ y=y',\ z=z'.\quad \tag{1}$$  (The purpose of restricting the domain to integers $>1$ is to remove obvious counterexamples that arise from equations like $x\uparrow (a\cdot z) = (x\uparrow a)\uparrow z\ \ $ or $\ \ 2\uparrow^y 2=4\uparrow^{y'} 1\ \ $ or $\ \ 1\uparrow^y z=1\uparrow^{y'} z'.$)  Proof:  Suppose, for the sake of contradiction, that there is a counterexample to $(1)$, in which the LHS of the implication holds but not the RHS. Then the LHS is a nontrivial equation for some hyperoperation(s) beyond exponentiation, which is impossible as per $(*)$. QED


How to find out the impact factor of a journal?

My paper was accepted in "". It has been indexed in notable websites like DBLP, ACM, .... However, I can't find any impact factor on the website or on the web.   How to find the impact factor of a journal?


If string contains ', replace with \' in SQL query

I'm trying to write a query using a variable passed through a URL, the problem is that a lot of the item names contain characters like ' or +, they weren't being passed properly through the URL, and those special character were being ignored(although I checked and couldn't see that they were reserved) Anyways, to get around this I used PHP function rawurlencode(), and rawurldecode() to pass the value as an encoded string, and on the receiving end I use the function to the decoded string. This works, and gives me the value I need to search for in the database, however when writing me query like so:  $name = rawurldecode($_GET["name"]);  $sql = "SELECT name, address, phone_number, hours_weekday, hours_weekend, description, email, food, pool, tv, dancing, late         FROM pubs WHERE name LIKE '" . $name . "'";   If the name was something like Darby's, the ' after the why acts as the end of the string in the statement, so what I am looking to do, is IF the string contains character ' then replace it with \' to escape it. Does anyone know how to do this or if it's possible?  Thank you!


Missing space/Storage space running out Galaxy S2 [tried almost every solution I can find!]

I periodically get this error on my phone. It will say the internal storage is running out but when I check the storage use it will say:  Total space 1.97 GB Available: 182MB Apps: 622 MB Cached 11.70 MB  This time, I checked my android/data folder and it said Spotify was using 1GB of space (in addition to all the space it is using in my other storage), so I deleted the Spotify cache and uninstalled it, then wiped my cache in recovery, but I didn't end up with any extra space afterwards.  I've deleted the log and LOST.DIR folders.   I can't seem to free up any more space. Every time this happens I have to factory reset and reinstall cyanogen (I'm running CM 10.1.3 now) to recover storage space, but each time it happens again eventually. I tried updating to a newer version of CM 10.1.3 but that doesn't help either.  UPDATE: I went through my apps to see if there was data I could get rid of there. I found 268MB in my Twitter app cache, but when I tried to clear the cache it wouldn't move. I uninstalled twitter but it didn't free up any storage space...  What am I doing wrong?  (Thanks!)


Background Recently my phone got stolen from my pocket and then I was almost thrown in street and run over by a car. The police won't move a finger because of a new law, which means I'll have to wait for over a year to get it back, but of course I did file a complaint with all the documents regarding the ownership of the phone. Question Is there any possibility of tracking your phone considering the fact that you have no pre-installed or rooted app and even if you do have it they can do factory reset/boot or do a full wipe? Can you track your IMEI or is there a service that could track it for you?


"No X11 DISPLAY variable" - what does it mean?

I am trying to install a Java application on my Linux machine (Slackware).   I have received the following error, and I do not understand it.   Could you advise me how to approach the problem? Thank you.  Here is what I get: (I see that some X11 DISPLAY variable needs to be set, but what value should I give it and how?)  ~$ java -jar gate-5.0-beta1-build3048-installer.jar - ERROR -  java.awt.HeadlessException: No X11 DISPLAY variable was set, but this program performed an operation which requires it. java.awt.HeadlessException: No X11 DISPLAY variable was set, but this program performed an operation which requires it. at java.awt.GraphicsEnvironment.checkHeadless(Graphic sEnvironment.java:159) at java.awt.Window.<init>(Window.java:407) at java.awt.Frame.<init>(Frame.java:402) at net.sourceforge.mlf.metouia.borders.MetouiaDotsBuf fer.<init>(MetouiaDotsBuffer.java:105) at net.sourceforge.mlf.metouia.borders.MetouiaDots.<i nit>(MetouiaDots.java:66) at net.sourceforge.mlf.metouia.borders.MetouiaToolBar Border.<init>(MetouiaToolBarBorder.java:49) at net.sourceforge.mlf.metouia.MetouiaLookAndFeel.ini tComponentDefaults(MetouiaLookAndFeel.java:241) at javax.swing.plaf.basic.BasicLookAndFeel.getDefault s(BasicLookAndFeel.java:130) at javax.swing.plaf.metal.MetalLookAndFeel.getDefault s(MetalLookAndFeel.java:1591) at javax.swing.UIManager.setLookAndFeel(UIManager.jav a:537) at javax.swing.UIManager.setLookAndFeel(UIManager.jav a:581) at com.izforge.izpack.installer.GUIInstaller.loadLook AndFeel(GUIInstaller.java:373) at com.izforge.izpack.installer.GUIInstaller.<init>(G UIInstaller.java:116) at sun.reflect.NativeConstructorAccessorImpl.newInsta nce0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInsta nce(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newI nstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Construc tor.java:513) at java.lang.Class.newInstance0(Class.java:355) at java.lang.Class.newInstance(Class.java:30 at com.izforge.izpack.installer.Installer.main(Instal ler.java:62)


I am using a HP Envy Laptop, 256 GB SSD and 8 Gb Ram. I want to install Ubuntu 18.04.4. LTS. what are the partitions i need and what is the best size and which filesystem i shall use for each.  How much disk space shall i allocate for:  / /boot /usr /var /opt /tmp swap what others i need to add?  please suggest.


Prove $f:[a,b]\rightarrow \mathbb{R}$ is constant function.

Let  $f:[a,b]\rightarrow \mathbb{R}$ s.t $f(a)=0$. If $f$ is differentiable on $[a,b]$ and there exist $C  \in \mathbb{R}$ s.t $|f'(x)|  \leq C|f(x)|$ for all x $ \in [a,b]$, then $f(x)=0$ for all $x  \in [a,b]$  My attempt:  |$f'(a)| \leq C|f(a)|=0\Rightarrow f'(a) = 0$  Let $\epsilon=\frac{1}{C}$, then there exist $\delta > 0$  s.t for all $x \in (a,b)$ if $x\in (a,a+\delta)$, then $\frac{|f(x)|}{x-a}<\frac{1}{C}$ thus $$|f'(x)|\leq C|f(x)|<|x-a|<\delta$$  I do not know what to do from here.  Edit: I could try to think about $f'(b)$: If $f'(b)>0$ or $f'(b)<0$, then find some contradiction.


I'm creating new input field with JQuery that include a remove button. The remove button works on the original element but does not work on those that were created using JQuery.  document after two new email fields added  <fieldset>                 <legend>Send Email</legend>                 Emails(s) to send notice to.
                     <input type="email" name="emails[]" style="cursor: auto; background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAABHklEQVQ4EaVTO26DQBD1ohQWaS2lg9JybZ+AK7hNwx2oIoVf4UPQ0Lj1FdKktevIpel8AKNUkDcWMxpgSaIEaTVv3sx7uztiTdu2s/98DywOw3Dued4Who/M2aIx5lZV1aEsy0+qiwHELyi+Ytl0PQ69SxAxkWIA4RMRTdNsKE59juMcuZd6xIAFeZ6fGCdJ8kY4y7KAuTRNGd7jyEBXsdOPE3a0QGPsniOnnYMO67LgSQN9T41F2QGrQRRFCwyzoIF2qyBuKKbcOgPXdVeY9rMWgNsjf9ccYesJhk3f5dYT1HX9gR0LLQR30TnjkUEcx2uIuS4RnI+aj6sJR0AM8AaumPaM/rRehyWhXqbFAA9kh3/8/NvHxAYGAsZ/il8IalkCLBfNVAAAAABJRU5ErkJggg==); background-attachment: scroll; background-position: 100% 50%; background-repeat: no-repeat;">x

<input type="email" name="emails[]">x

<input type="email" name="emails[]">x

                     Add Another Email

                     Send Email
             </fieldset>   Script


I'm new to Gnome, and I don't really like it. So that's exactly why I installed Unity 7. So far so good, Unity works like a charm, much better than Gnome, at least this is my opinion. However, now I have 2 settings app,  2 calculators, 2 networks managers, 2 of everything. Is there any way to remove gnome 3 without messing up at all Unity? I don't really like to search an app and instead of showing up only 1 it shows at least 3 different apps with the same icon. Is there any way? Thank you!


I am using this  for d in ./*/ ; do (cd "$d" && cp -R ../lib . ); done  in a shell script to copy lib folder in all subfolder inside my parent directory . But the lib folder also getting copied inside lib . How to avoid that ?


I am reading the paper, entitled "Artificial uniaxial and biaxial dielectrics with use of two-dimensional subwavelength binary gratings" by Eric B. Grann, M. G. Moharam, and Drew A. Pommet.   In the paper they mention this formula:        Do you know how it can be derived and where it comes from ?


Find all $n \in \mathbb{Z^+}$ such that $\phi(n)=4$

I know that there is a similar post, but I 'm trying a different proof. I will write $P$  for the set of all positive prime numbers. Question: If $\phi$ is Euler's Phi Function, we want to find all $n \in \mathbb{Z^+}$ such that $\phi(n)=4$. Answer: Let $n=p_1^{n_1}\dotsb p_k^{n_k}\in \mathbb{Z}^+$ be the factorisation of $n$ in to primes. Then $$\phi(n)=p_1^{n_1-1} \dotsb p_k^{n_k-1}(p_1-1) \dotsb (p_k-1)=4.$$ So, for any $i \in \{1,2,\cdots,k\}$ we have $p_i-1|4$. Hence, $$p_i-1\in\{1,2,4\} \iff p_i\in \{2,3,5\} \subset P.$$ Now, we can see the primes that $n$ contains: $n=2^{n_1}3^{n_2}5^{n_3}$, where  $n_1,n_2,n_3 \in \mathbb{Z}^+$. So, \begin{align*} \phi(2^{n_1}3^{n_2}5^{n_3})=4 \iff \phi(2^{n_1})\phi(3^{n_2})\phi(5^{n_3})=4  \tag{*} \end{align*} The possible cases for $n_i$ are:  $n_1=1,2,3\implies \phi(2)=1,\phi(2^2)=2, \phi(2^3)=4$ respectively $n_2=1 \implies \phi(3)=2$ $n_3=1 \implies \phi(5)=4$  All the posible combinations for the relation (*) are $\phi(5)$, $\phi(5)\phi(2)$, $\phi(3)\phi(2^2)$, $\phi(2^3)$. So, $$n \in \{5,10,12,8\}.$$ Is this completely right? Thank you.


java.util.Random makes 100 times faster computation?

I am totally lost for words, i have no idea what's going on...   //import java.util.Random;  public class TestInProgress {     public static void main(String[] args) {         long start, end;         long average;  //      Random random= new Random();      for(int j=0; j<5; j++) {          average= 0L;         for(int i=0; i<100; i++) {              start= System.nanoTime();                 double temp= fastComputeSigm(0.0);             end= System.nanoTime();             average+= (end - start);         }          average= average/ 100L;         System.out.println("AVERAGE FASTCOMPUTE: "+average);          average= 0L;         for(int i=0; i<100; i++) {              start= System.nanoTime();                 double temp= Math.exp(0.0)/(1.0 + Math.exp(0.0));             end= System.nanoTime();              average+= (end - start);         }          average= average / 100L;         System.out.println("AVERAGE SIGMOID: "+average);     } }  static double fastComputeSigm(double value) {     return 0.0; }   }  The most surprising is the output:     AVERAGE FASTCOMPUTE: 98 AVERAGE SIGMOID: 38625 AVERAGE FASTCOMPUTE:   106 AVERAGE SIGMOID: 65 AVERAGE FASTCOMPUTE: 299 AVERAGE SIGMOID: 201   AVERAGE FASTCOMPUTE: 36 AVERAGE SIGMOID: 65 AVERAGE FASTCOMPUTE: 53   AVERAGE SIGMOID: 57   see that? I uncommented Random (and its import) What would you expect? output:     AVERAGE FASTCOMPUTE: 90 AVERAGE SIGMOID: 324 AVERAGE FASTCOMPUTE: 131   AVERAGE SIGMOID: 73 AVERAGE FASTCOMPUTE: 217 AVERAGE SIGMOID: 36   AVERAGE FASTCOMPUTE: 53 AVERAGE SIGMOID: 12 AVERAGE FASTCOMPUTE: 53   AVERAGE SIGMOID: 69   I tried this on eclipse Oxygen.3a Release (4.7.3a) I'm using java 10.0.2 My computer has a Intel Core i5-7300HQ with those cache memories : L1 256, L2 1024, L3 6M I run on windows 10  note: I tried to make the forloop with j<1,2,3,... several times no helping the first sigmoid always has absurd time length  edit: tried launching it with windows commandline (javac and java), same result


I want to search an associative array and when I find a value, delete that part of the array.  Here is a sample of my array:      Array (     [0] => Array         (             [id] => 2918             [schoolname] => Albany Medical College             [AppService] => 16295C0C51D8318C2         )      [1] => Array         (             [id] => 2919             [schoolname] => Albert Einstein College of Medicine             [AppService] => 16295C0C51D8318C2         )      [2] => Array         (             [id] => 2920             [schoolname] => Baylor College of Medicine             [AppService] => 16295C0C51D8318C2         ) }   What I want to do is find the value 16295C0C51D8318C2 in the AppService and then delete that part of the array. So, for example, if that code was to run on the above array, it was empty out the entire array since the logic matches everything in that array.   Here is my code so far:              foreach($this->schs_raw as $object) {                 if($object['AppService'] == "16295C0C51D8318C2") {                     unset($object);                 }         }


How can I factor the polynomial $125x^3 + 216$?

$$125x^3 + 216$$  I have tried to factor it but because the square root of $216$ is a decimal, I can't figure out how to do the problem.


Unable to send _$GET['username'] into the Database?

For some strange reason I cannot insert a username into the database, but when I change the value into any integer it works once I click like, it works.   $postid = $_POST['postid']; $userid = $_GET['username']; $result = mysqli_query($dbh,"SELECT * FROM user_images WHERE id=$postid"); $row = mysqli_fetch_array($result); $n = $row['likes']; mysqli_query($dbh,"INSERT INTO likes(username, postid) VALUES($userid, $postid)"); mysqli_query($dbh,"UPDATE user_images SET likes=$n+1 WHERE id=$postid"); echo $n+1; exit();


This has always annoyed me. Bluetooth turns on when I boot up my laptop, and it's a real drain if I forget to turn it off. It's been a year, and I'd like to find the solution, finally, here.  Thank you :)


If a study indicates no correlation between two variables, does it also indicate a lack of casual relationship?

Of course, correlation does not equal causation. But I am having trouble understanding if there is no correlation between two variables, would this indicate a lack of casual relationship between them as well?  If possible, I would really like an example to help wrap my head around this.


For the Running Ragged hat, do you need 150 on each individual site, or collectively?

The  say:     earn 150 reputation points on three different sites (not including Stack Overflow) within 15 days.     Does this mean that you must collectively earn 150 reputation points on 3 sites, or 150 points on each individual site?


How to diagnose Blue Screens in Windows 7 (64bit)

Using programs like  and  you can see the BSOD and the errors but how do you tell exactly what's causing the BSOD?   I'm not sure if it's because of bad hardware, bad driver software or OS corruption. The computer seems to crash randomly at different points sometimes when being used, sometimes under load in games and sometimes when in screen saver.   I think there's a website that exists that matches the numbers in the BSOD to certain hardware so it can be identified but I can't remember what it's called - any ideas?  Even if I can find out the general area of the computer at fault that would be helpful such as RAM voltages, motherboard chipset temps etc.  Any solutions?  UPDATE: I've changed the memory modules but crashes still persistent. All different drivers and files I can't pinpoint the fault. Other info: AV = Avast, Firewall = Comodo and latest win 7 video drivers installed.


Fourier transform in Klein-Gordon equation

I'm Solving (or at least trying to solve) 4 Klein Gordon equation with sources (Maxwell equations) with the Green function method, therefore I have  $$ \Box G(x,x')= \delta^4(x-x') \tag{1}$$  Where $G$ is the green function and the arguments of the functions are 4-vectors.  To Find the Green function we use the Fourier transform, and here there is my problem, which is mainly a terminology problem. We write  $$ G(x-x') = \frac{1}{(2 \pi)^4} \int d^4k \tilde{G}(k) e^{-ik \cdot (x-x')} \tag{2}$$  Now to my definition of Fourier Transform which is $$ (F f)(x)= \tilde{f}(x)= \frac{1}{(2 \pi)^{n/2}} \int \,\tilde{f}(k) e^{-ix \cdot k} d^nk \tag{3}$$  I have that $G$ is the Fourier transform of $\tilde{G}$, apart from a factor $(2\pi)^{1/2}$ missing in equation $(2)$ which i cannot explain.   Is my view right? Both my book and my notes says that $\tilde{G}$ is the Fourier transform of $G$ while in my opinion $\tilde{G}$ is the inverse Fourier transform of $G$.   I mean in $(2)$ I'm Fourier transforming  the inverse Fourier transform of $G$ and that's why I obtain $G$, which is by means of the inversion equation: $$ f=(F(\overline{F} f)  \tag{4}$$  Where $\overline{F} f$ is the inverse Fourier Transform.  I'm probably missing something and the answer may be banal, but, if I am, where am I wrong? And why is there a missing factor of $(2\pi)^{1/2}$ ?   Hoping that someone enlighten me, thanks in advance for any help.


Can switching to Ubuntu free up disk space?

I have a budget sized hp laptop that has a small hard drive (not upgradable) and windows use 90%. When my cache gets even a little filled it slows down to a crawl.  I understand ubuntu takes up less hard drive space. Would it be worthwhile to switch to Ubuntu? Is it even possible, considering I have little space for swapping? uses


Where do I find Ubuntu's PGP signatures and signing keys?

where can I find PGP signatures and signing keys for Ubuntu? I want to verify the download, but the only thing I can find are the MD5 hashes ().  I can't imagine that Ubuntu doesn't offer a way to check the integrity of an ISO image.


Installed .sty with tlmgr but latex can't find it

I have installed Tex live 2013 Version 3.1415926 and I want to install the package mdframed.  My first try was to enter in the terminal  tlmgr install mdframed   but the terminal responded to me that I am not allowed to do that. When I entered  sudo tlmgr install mdframed   I gained the message "tlmgr: command not found". So I typed   sudo -i   added the tex path in /root/.bashrc and finally entered  tlmgr install mdframed tlmgr update mdframed   and it worked! But if I compile my latex file the error   ! LaTeX Error: File `mdframed.sty' not found.   remains. Any Idea how to solve it?  EDIT: Output of  kpsewhich mdframed.sty   is  /usr/local/texlive/2013/texmf-dist/tex/latex/mdframed/mdframed.sty


How does the term $|\psi\rangle\langle\psi|$ come from while calculating the expectation value?

Suppose there're two systems $A$ and $B$, if we're in a pure state $|\psi\rangle\in\mathbb{H}_a\otimes\mathbb{H}_b$, let $\hat A$ be an operator acts on $\mathbb{H}_a$, and $|\psi\rangle=\sum_{i,j}\psi_{i,j}|a_i\rangle|b_j\rangle$. Then, the expectation value of A with respect to the state $|\psi\rangle$ can be calculated as: $$ \langle A\rangle_{\psi}= Tr_{\mathbb{H}_a\otimes\mathbb{H}_b}(A|\psi\rangle\langle\psi|)=\sum_{i,j}\langle a_i|\langle b_j|A\otimes\mathbb{1}_B|\psi\rangle\langle\psi|a_i\rangle|b_j\rangle=... $$ I'm very confused how those two equalities coming from? Especially for the term $|\psi\rangle\langle\psi|$ in the sum, can I understand their function as generating a $\psi$ matrix with different constants $\psi_{i,j}$? Thanks!!


Unity installed version higher than game project version - can't open the game project anymore

Long story short - I had to uninstall Unity and Unity Hub and reinstall them again. I ended up installing Unity version 2020.2.1f1. Some of my game projects were made using version 2020.1.6f1 Now I cannot open them - there is a yellow warning triangle next to those games in Unity Hub. I am installing version 2020.1.17f1 as I type these. So my questions:  Is there no backwards compatibility between newer versions of Unity and older games? How do people deal with this? I've heard people transition their games during development into newer versions of Unity but I wasn't even able to open the games made with older version. How would I go around this if I had spent 2 years or more of development time and was suddenly locked out from my game project - how do I prevent situations like these?  Here are my Unity versions installed:  And here are my games (tutorials mostly):  I may have answered my own question, but still need your input guys. I just noticed that there is a 'Select Version' dropdown on the right that allows me to open a game project in Unity version I have installed on my system. Is this how you deal with those issues?


What's the exactly the definition of the class in mathematics?

Recently I study the category and I confused with the concept of the class.Sometimes a class is not a set,and sometimes it said a class is.What I know the class is the equivalent class.So what's the class?


In the past Ive always brought dedicated sound cards for my computers, however these days most motherboards have some sort of audio support built in, in fact many even are capable of surround sound, and a large amount of the audio processing can be done completely in software anyway (eg as I understand, XAudio2, which is set to replace DirectSound does all processing in software, just using the hardware to actually send the final audio data to the speakers).  So considering those things is there actually any point to fitting a dedicated sound card in modern computers?  EDIT: So does the improved quality of dedicated audio hardware apply to software based audio solutions which seem to be becoming more popular?


Auxiliary files in other directory than .tex file

I want to make one global folder for all auxiliary files which are produced while compiling .tex file (i.e. .aux, .log, .out, .toc, synctex.gz). I use TeXstudio and I found that I have to change compiling options in Configure TeXstudio > Commands. Now I have   pdflatex.exe -synctex=1 -interaction=nonstopmode -aux-directory="C:\Latex_Aux_Global" %.tex    for PdfLaTeX, which moves all files except .synctex.gz file. It is possible to move this file to the same directory as all auxiliary files?  My second problem is that I need to use also BibTex and MakeIndex connected with this global folder Latex_Aux_Global. For BibTex I have following command  bibtex.exe "C:\Latex_Aux_Global"/% -include-directory="C:\Latex_Aux_Global".   I don't know in what way I can make such command for MakeIndex. When I use   makeindex.exe "C:\LaTeX_Aux_Global"/%.idx    to MakeIndex, while compiling I get error Can't create output index file C:\LaTeX_Aux_Global/document.ind. I will be gratefull for any suggestions.


Orthogonal Projection onto the Affine set $ \left\{ x \mid A x = b \right\} $

suppose we have a vector $x \in \mathbb{R}^{n}$, and a closed convex set $C \in \mathbb{R}^{n}$. $C =\{x|Ax=b\}$  how to calculate the vector $y \in \mathbb{R}^{n}$, which is the projection of $x$ onto set $C$. The vector $y\in C$ and have the smallest distance to $x$.