"Standard" ways of telling if an irreducible quartic polynomial has Galois group C_4?

The following facts are standard: an irreducible quartic polynomial $p(x)$ can only have Galois groups $S_4, A_4, D_4, V_4, C_4$. Over a field of characteristic not equal to $2$, depending on whether or not the discriminant $\Delta$ is a square and whether or not the resolvent cubic $q(x)$ is irreducible, we can distinguish four cases:   If $\Delta$ is not a square and the resolvent cubic is irreducible, then the Galois group is $S_4$. If $\Delta$ is a square and the resolvent cubic is irreducible, then the Galois group is $A_4$. If $\Delta$ is a square and the resolvent cubic is reducible, then the Galois group is $V_4$. If $\Delta$ is not a square and the resolvent cubic is reducible, then the Galois group is either $D_4$ or $C_4$.   How can we resolve the ambiguity in the last case? For $p$ a monic polynomial in $\mathbb{Z}[x]$, I know the following approaches:   In the simplest cases one can work directly with the splitting field. But this is rare, although it can work if $p = x^4 + ax^2 + b$ for some $a, b$.  If $p$ has two complex roots (equivalently, if the discriminant is negative), there is a transposition in the Galois group, so the Galois group is $D_4$. If $p$ factors as the product of two linear factors and an irreducible quadratic factor modulo a prime, there is a transposition in the Galois group, so the Galois group is $D_4$.    In practice, the last two often work to identify a Galois group of $D_4$ (and in principle it must eventually work by the Frobenius density theorem). But I don't know a corresponding practical way to identify a Galois group of $C_4$. There is a criterion due to Kappe and Warren which I learned about from one of Keith Conrad's expository notes . However, in an upcoming exam I'm taking, I'll only be able to cite results proven in the course, and this criterion isn't one of them.   So what are my other options in general?


Usage of "they" / "them" / "their" when the person's gender is not known

I know that one can use "they" / "them" / "their" in place of "he" / "him" / "his" or "she" / "her" / "hers" when the subject's / direct object's gender is not known; for instance, just looking at the default user's about me section on Stack Exchange sites:     Apparently, this user prefers to keep an air of mystery about them   My question is what happens when someone wants to reference the subject using a pronoun instead.  Should the verb be conjugated accordingly to the pronoun? E.g.:     Apparently, they prefer to keep an air of mystery about them   Or should the conjugation be retained? E.g.:     Apparently, they prefers to keep an air of mystery about them   The former looks unclear because it wouldn't allow the reader / listener to understand if the writer / speaker is talking about a single person or about a group of people, however the latter sounds very weird, at least just to the non-native speaker which I am.


How to install UBUNTU without LiveCD, LiveDVD or LiveUSB?

Context  I'm using Windows 8.1 on a laptop with broken USB ports. I want to install UBUNTU and remove Windows.   I tried to use Unetbootin but I got error 15 in the installation.  Any help for a newbie?  I'd appreciate it.


What's causing this orange light leak, vertical band, from an Olympus OM-1?

My Olympus OM-1 typically doesn't have problems, but these two shots seems to show some kind of light leaks.  What I gathered with light leaks is that orange ones are probably from behind the film. The shutter is a horizontal cloth shutter, if that helps any.  The rest of the roll doesn't have any of these problems, which makes it even more interesting to diagnose...  Edit: The negatives


What is the minimum temperature to keep the hot water heater at?

Our hot water heater produces hot water, but not super hot, is there a minimum temperature I need to keep it at?  I don’t like it when the hot water is scalding, but I want to be safe.


No.  Not those questions.       The white blobs should say "Questions".  The don't reappear after refresh and aren't consistently missing between sites. Navigating around fixes the issues.   I'm tempted to  but I thought I'd flag this up anyway.


Hide page numbering but retain header/footer

I would like to remove page numbering on a specific page. However, the header and footer should remain intact. If I try:  \thispagestyle{empty}   The header and footer disappear. What is the recommended way of removing just the page number?


How do you print out all properties of an object and the values assigned to them in JavaScript?

Lets say you have an object you created in javaScript and you want to print out the property and the corresponding value, how would you do that?  Here is an example below.  Obviously in real life I wouldn't keep making objects, but bear with me here.    var houseA = {     county: "Falls County",     school: "Trinity West Elementary School",     square_feet: 2500,     specs: "3 bedroom and 2 bath" };  for(var prop in houseA) {     document.write(prop); }  //This would out put  county school square feet specs   How would you make it output the values with the properties?  I know you can do it mannually by doing below.  document.write(houseA.county); document.write(houseA.school);     so on and so fourth.


How to call a @future method from Batch Apex?

Can anyone please give me an example or an idea on how to solve this problem?


Computing $f(x)$ if $\int_1^{xy} f(t) dt = y \int_1^x f(t) dt + x\int_1^y f(t) dt$ and $f(1) = 3$

This is a problem from Apostol, Calculus, Volume I, Chapter 6.9 (p. 238), that I was hoping someone could help with:     A function $f$, continuous on the positive real axis, has the property that $$\int_1^{xy} f(t) dt = y \int_1^x f(t) dt + x \int_1^y f(t) dt$$   for all $x > 0$ and all $y > 0$.  If $f(1) = 3$, compute $f(x)$ for each $x > 0$.   My initial thought was to use properties of the integral to write:  $$\begin{align*}  \int_1^{xy} f(t) dt & = \int_1^x f(t) dt + \int_x^{xy} f(t) dt \\ & = \int_1^x f(t) dt + x \int_1^y f(xt) dt \end{align*}$$  and  $$\begin{align*} \int_1^{xy} f(t) dt & = \int_1^y f(t) dt + \int_y^{xy} f(t) dt \\ & = \int_1^y f(t) dt + y \int_1^x f(yt) dt \end{align*}$$  Then each of these is also $=y \int_1^x f(t)dt + x \int_1^ f(t)dt$ from the given equation of the problem.  I cannot seem to pull an equation for $f(x)$ out of this though (I might be missing some very simple manipulation...).  I also thought in terms of letting $A(x) = \int_1^x f(t)dt$, so the problem is giving us a functional equation: $$ A(xy) = yA(x) + xA(y)$$  This has obvious similarities to the functional equation of the logarithm.  This problem is in the section of the text with the definition of the logarithm as an integral.  I'm self-studying, so this isn't homework.  Hints or full solutions are equally welcome.  Thanks for the help.


Is it possible to make an EXACT ISO of my system to put on other computers?

I am new to linux, but had a question. I am getting in the business of buying old computers, putting Linux on them, then donating them to students who don't have their own computer at home. I have gone through and installed Xubuntu on my system, installed/uninstalled all the software that I want/need, and now want to know if there is a way that I could make an ISO of my system, and put it onto ANOTHER computer, and still have all of my tweaks, and programs ready to go after the ISO has installed. That way I don't need to go through and spend an hour or two on every computer.   What programs would you recommend for creating an ISO like this?   Thanks, Tobin


How can i put the gcc warning messages in a text file?

I wished to know if someone knew how to put the compilation warnings of GCC in a text file ?  For example :  I wrote (willingly) a undefined function foo(). So gcc tell me :  warning: implicit declaration of function 'foo [Wimplicit-function-declaration]   How can i get this line written in a text file ? I search for an option in the man page of gcc :    but didn't find anything about that. I tried the commands echo and tee to do that but those commands only catch the compilation line (eg : ... gcc -o test test.o main.o ...)


Running Ubuntu within Windows 10 pro environment

Good day, I have installed a clean version of the latest Windows 10 pro and Ubuntu 20.04Lts. Did the upgrade to WSL2. When I click on the Icon of Ubuntu I get a rectangular black sceen on my desk top with at the top an orange Ubuntu long side at the top. It mentions now: root@DESKTOP-S9VN01H:#. How do I get to the Ubuntu desktop? Can you please assist me how to get further, thank you.


Can I have more than four non-basic lands with the same name in my deck?


I have an iPhone 5 - not yet jailbroken - running iOS 7.0.6 (via recent OTA update). I heard about the 7.1 update today and thought if I would ever jailbreak, this would be the time. evasi0n's page states "Over The Air updates of iOS 7 are known to create an issue and make the jailbreak fail." So, I download the appropriate 7.0.6 IPSW and try to restore through iTunes. But it appears Apple has already closed this SHSH blob (today, drats) and iTunes errors out with the "This device isn't eligible for the requested build" error.   I plan on not upgrading to 7.1 until this answer is a definitive "no".  My question: Is there a way for someone in my situation running 7.0.6 (OTA) to Jailbreak?


As a new user, how do I gain reputation/participate in SO if all my questions have already been answered?

I like the community and appreciate the great service it's been to me over the past few months.  Sometimes I want to show my support for a great answer or comment, but I can't because I'm a new user and have only 1 reputation. It seems like the only way to gain the requisite 15 reputation (for voting) is to ask questions?  Until now I didn't have any questions that weren't already answered by the community. Is this the only way? Won't this one day lead to no new users not being able to participate?


QQ.com does not accept email from our domain

We are running a mailing list by OpenEMM for our customers. However, email addresses in the @qq.com are not delivered.  It seems to us qq.com does not accept any email from our domain.  How can this be fixed?  p.s. SPF record is already set up for our domain.  Typical maillog entries:  Sep  9 00:06:02 MAILER sendmail[982]: 0000DB00000001922: to=<MASKED@qq.com>, delay=00:03:11, xdelay=00:00:09, mailer=esmtp, pri=0, relay=mx3.qq.com. [103.7.29.244], dsn=5.0.0, stat=Service unavailable Sep  9 00:14:51 MAILER sendmail[1067]: 0000DB00000001B8A: to=<MASKED@qq.com>, delay=00:12:00, xdelay=00:00:04, mailer=esmtp, pri=0, relay=mx3.qq.com. [103.7.29.244], dsn=5.0.0, stat=Service unavailable


How to get static member of extended class

I want to override operator+ for my classes Fridge and TV (to make it add power consumption), so I made them extend Rtv class which should override that operator, however I don't know how to get proper POWER_CONSUMPTION field value if both Fridge and TV have different overriden value. To be more precise i want to achieve this to be possible:   Fridge fridge = new Fridge();   Tv tv = new Tv();   int totalPowerConsumptionOfFridgeAndTv = fridge + tv;  My idea for Rtv class was:   class Rtv {     private const int pOWER_CONSUMPTION= 0;      public static int POWER_CONSUMPTION=> pOWER_CONSUMPTION;      public static int operator+ (Rtv a, Rtv b)     {          return a.GetType().POWER_CONSUMPTION + b.POWER_CONSUMPTION;     } }  But simply doesn't work.


I'd like to listen to music on my home server from work. Both are Ubuntu boxes running pulseaudio. It seems from researching that applications communicate to the PA server via TCP on port 4317, so I figured it should be as easy as:  me@work: ssh -YR 4317:localhost:4317 me@home   At this point I can run rhythmbox from the ssh session with X11 forwarding, and I assumed rhythmbox would be transparently talking to pulseaudio over the reverse tunnel, resulting in the music playing on my work machine. However instead it appears that the music still plays on my home computer. I've tried messing around with PULSE_SERVER as well to no avail.  Has anyone accomplished something similar? It seems like this should be relatively simple due to pulseaudio's design. I've played around with mounting my music library via sshfs instead but I'd really like to have one set of metadata/app settings/playlists and such. Thanks for any tips!


how to load keyStore and trustStore files from a java Jar file project and use them to initialize SSLContext?

I use ssl to secure RMI and JMS communications between clients and server. I add keyStore and trustStore files to resource folder of my project. When the project run through Netbeans, these file are loaded without any problem, using below codes:  System.setProperty("javax.net.ssl.keyStore", "src/main/resources/certificates/keyStore.ks"); System.setProperty("javax.net.ssl.keyStorePassword", "pass"); System.setProperty("javax.net.ssl.trustStore", "src/main/resources/certificates/trustStore.ts"); System.setProperty("javax.net.ssl.trustStorePassword", "pass");    But, when I run this project through its jar file, these files cannot be loaded.   Is there any alternate way to config SSL instead of using System.setProperty() and specifying the paths to keyStore and trustStore files?   Also, it works in both modes (run through Netbeans and Jar file).


How far can you go with rm -rf / as root

If you are root, and you issue   rm -rf /    Then how far can the command go? Can you recover data from this kind of an action? Even after the binaries are gone, would the running processes still be active? What would it take to make the same physical machine boot again? What files would you need to restore to make this happen?  I could try this on a VM and see, but I want to know the rationale behind what to expect if I do this.


When a polynomial f(x) is divided by (x-3) the remainder is -9 and when f(x) is divided by (2x-1) the remainder is -6 . Find the remainder when f(x) is divided by (x-3)(2x-1).  I do not know how to determine the remainder


another question on surds and how to use math symbols in this site

$$\sqrt{ 3x }= x + \sqrt {3}$$  this is what i tried   $$\sqrt{ x }= (x + \sqrt {3})^2\\ = x^2 + 3 $$  Give x in the form  $$A \sqrt {B} + C $$ Can you show me how this is done step by step.   The answer I have in the book is:  $$\frac {1}{2} \sqrt{3} + \frac {3}{2} $$


Using the chinese remainder theorem to find the last two digits of $49^{19}$

I am trying to find the last 2 digits of $\ 49^{19}$ but I am having some trouble. So far I know that   x = $\ 49^{19}$ mod 100 x = $\ 49^{19}$ mod 25 x = $\ 49^{19}$ mod 4  I can then apply the CRT and set u = 4 $\ *$ ( $\ 4^{-1}$) mod 25 and v = 25 $\ *$ $\ 25^{-1}$ mod 4. However I am having trouble finding x.


How come no information can travel faster than light when we can measure a black hole's mass?

So I learned about the Schwartzchild radius, which is the radius of an object's event horizon. But how we define an event horizon is that it's a region of space where the gravitational acceleration light could not escape it. And according to Einstein no information can travel faster than light, therefore no information can escape from within a black hole, so how come we be able to observe a property of the singularity: its mass? According to Schwartzchild's equations we can deduct the mass of a black hole from an observable property, which is the radius of its event horizon of course. Furthermore, gravity only travels at the speed of causality/light, for instance if the sun disappeared we would continue orbiting it for 8 minutes until the deformed space-time comes back to normal, so how come any object outside of the black hole even know there is gravitational pull in that region of space?


I am missing an episode in season 5 of Game of Thrones. Suddenly, for me, Sansa is married to Ramsay. Why and how did Littlefinger allow this to happen?


I don't understand why a set with n elements has 2^n subsets. How is this calculated? I realize that {123} has empty set - 1-2-3-1,2-1,3-2,3-1,2,3 but how is the formula derived?


To update packages, I do  sudo apt-get update sudo apt-get uprgade   but it never finds security update automatically and I get this notification:   How do I install security update using apt?


Return a blank when cell reference is blank

I am using the following formula in a Google Sheets to calculate the number of days between two dates (dates are in columns G and AL):  =ARRAYFORMULA(if(row(A:A)=1, "Readmission Days", (G:G)-(AL:AL)))   It has to be an array because I am working with a Google Forms and entries are automatically populated into new rows.  The problem is that some of the cells in col AL are blank, so the formula is reading those dates as something else and returning a very large number. Also, when both cells are blank, the formula returns a 0, messing up my data.  How can I include something to ignore blank cells or just return a blank when one or both cell references is blank?


How good is a model if it can't predict a single positive class?

I have a training set of over a 100,000 points that is used to train a Logistic Regression Classifier (logit, since response is binary). The model is testing/fitted on a test set of 20,000 items. The test set is totally independent.   The ROC AUC value for this model is 0.85 which suggests that this is a good model. But I was not convinced. I picked a threshold $0.5$ (i.e., its classified positive if the model response $> 0.5$, negative if model response $< 0.5$).   At this threshold, I get the confusion matrix:  Confusion Matrix and Statistics            Reference Prediction     0     1          0 33307   679          1     0     0                 Accuracy : 0.98                              95% CI : (0.9785, 0.9815)     No Information Rate : 0.98                 P-Value [Acc > NIR] : 0.5102                              Kappa : 0                 Mcnemar's Test P-Value : <2e-16                        Sensitivity : 0.00000                      Specificity : 1.00000    So my question is, how good is the model if it is unable to predict a 'positive' class at 0.5 threshold?  My guess would be that the threshold of the model for labelling 'positive' is not $0.5$ in this case. Is this intuitive and make sense? Clearly the ROC AUC value is very high, which means that it does have a good TPR rate at lower thresholds.


With  \documentclass{standalone}  \usepackage{pgfplots}  \begin{document}  \begin{tikzpicture} \begin{axis}[samples=10, domain=0:pi] \addplot {x-sin(x)}; \end{axis} \end{tikzpicture}  \end{document}   I get a plot and an x axis from 0 to pi and labels 0, 1, 2, and 3.  What is the best way to get labels with pi instead of whole numbers on the axis?


Using semicolon to separate a background job from the following one?

Can we use semicolon to separate a background job from the following one?  $ nohup evince tmp1.pdf &; nohup evince tmp.pdf & bash: syntax error near unexpected token `;'


I cannot format my flash usb stick - newby user

I have the latest edition of ubuntu, formated my pc 1 week ago. I Right clicked on the USB flash partition and I sow the format option. It is not grayed out, I do the format, it shows no files when I open the usb file, but when I click on priorities, it shows 94% full.


When I delete a "word" in Bash, it will stop at certain characters like _ and /. For example, if I type  /foo/bar   and activate backward-kill-word (typically mapped to Alt-Backspace and/or Ctrl-w), the remaining text is  /foo/   . This does not correspond to $COMP_WORDBREAKS or . How can I detect (preferably in a running system, rather than the defaults in the code, since they presumably can be overridden) which characters are used to determine word breaks?


Achieving Super or Subscript graticule labels in QGIS Composer windows?

It is quite common for paper topographic maps to label the map graticule with ordinate values in a mixture of superscript and standard digits, eg. ⁴123⁰⁰⁰ to emphasise the significant digits.  The QGIS Map composer allows graticules (termed grids) to be drawn on the map, and the ordinate labels to be customised, but does not recognise HTML tags such as <sup>.  Is there any other way to achieve this effect?


How to reference equations (new to Latex)

\documentclass{article}   \newcommand{\dd}[1]{\mathrm{d}#1}  \begin{document} \begin{equation} \Delta A_2 = x^2 \end{equation}   This code puts a (1) next to this equation, and numbers later equations accordingly. If I want to reference this equation, say with:  And as you can see in Eq. #,    how would I link it so that if the equation number later changes, I don't have to update the text?


VirtualBox issuing error message "Kernel driver is not installed"

I am new to Ubuntu and VirtualBox is issuing the error message "kernel driver is not installed". I can't even remove it from my device. Here is a  with the error message with more details of the error I am receiving. Can someone help me please?


How do I solve $\int_0^1 \frac {\ln \frac {x^2 + \sqrt 3 x +1} {x^2 - \sqrt 3 x + 1}} x dx$?

I don’t know how to solve this integral. Can someone give me a step-by-step solution to this, explaining how to get to the exact result, please? PS: The answers given in the other question may not correspond to what my teacher is asking.


Can I use my phone as a WiFi-WiFi hotspot?

I have a (non-rooted) Sony Xperia Z3 with default Lollipop installed. One challenge I often run into is that I can connect to a WiFi network, and my friends with iPhone cannot (I've also encountered the opposite, but that's another topic). It seems the hotspot functionality only works with connection to a telephone network, and not as a regular WiFi-WiFi hotspot. Do any of you know of a built in functionality that will do this, or an app I can download that will solve this issue for me? Thanks :)


How set External Webcam as a default webcam?

I have HP 18 AIO Desktop, which has inbuilt web cam. How can I set an external Webcam (Logitech C170) as a default cam from command ? Is there any way, Please help me.  Cheese webcam booth or other software can do this but I wan to do it on system based so that it will be work on all webcam related software.  Thanks!  Birendra


Lost Apple ID password and security questions and answers

I lost my Apple ID password and security questions and answers. What do I do?


What is the depth-of-field preview button on my DSLR supposed to show me?

I'm fairly new to DSLRs and I've been exploring the functions on my new Canon 60D.  There's a button to the side of the lens described as the "depth-of-field preview button".  Based on the limited description in the manual, I thought this would give me a preview of how the photo would look in terms of what's in and out of focus when I'm using Live View.    When I press it though, despite jerking as if it's processing something, I see no difference in the LCD screen.  I've played with the aperture with no discernible effect.  Am I missing something?  What should I be seeing?


It looks like compiler doesn't recognize nextLine() value as string

Scanner scan = new Scanner(System.in);         AccountList accounts = new AccountList();                  accounts.addAccount(new BankAccount(100000, "Mark", "BA0021"));         accounts.addAccount(new BankAccount(367000, "John", "BA0022"));         accounts.addAccount(new BankAccount(94500, "Michael", "BA0023"));                  accounts.accessAccount("BA0021").checkBalance();         String temp = "BA0022";         accounts.accessAccount(temp).checkBalance();         **temp = scan.nextLine();         accounts.accessAccount(temp).checkBalance()**;  As you can see, I tried :         **temp = scan.nextLine();         accounts.accessAccount(temp).checkBalance();**  like the other two methods I tried and succeeded :         accounts.accessAccount("BA0021").checkBalance();         String temp = "BA0022";         accounts.accessAccount(temp).checkBalance();  And the console shows : Mark's  balance is $100000 John's  balance is $367000 **BA0023 Cannot Find an Account That Matches the ID** Exception in thread "main" java.lang.NullPointerException: Cannot invoke "ainsof26.project.banking.BankAccount.checkBalance()" because the return value of "ainsof26.project.banking.AccountList.accessAccount(String)" is null     at BankingApplication/ainsof26.project.banking.BankingApplication.main(BankingApplication.java:22)  Can you recognize what the problem here is? This is accessAccount method : BankAccount accessAccount(String id) {         for(BankAccount account: accountList) {             if(account.clientId == id) {                 return account;             }         }         System.out.println("Cannot Find an Account That Matches the ID");         return null;      }


Can I upgrade cmd.exe on Windows 8.1 to the Windows 10 version?

I work on a Windows 8.1 Enterprise PC. I Would like to upgrade my Command Line terminal (cmd.exe) to the one offered in the latest version of Windows 10, which has many handy features that the old one lacks. EDIT: I mean UI features like the automatic word wrap and the ability to maximize in the whole window. Is it possible?  I would prefer the traditional cmd.exe and not PowerShell.


Construction of $\sqrt{ab}$ user ruler and compass

Q. Given two line segments of length a and b. Draw a line segment of length $\sqrt{ab}$ using a ruler and compass.  I didn't get any idea how to approach to the solution.


Lookback Query utilizing Change Data Capture in SQL Server 2014?

I'm using SQL Server 2014 to maintain a small database and while looking for a way to keep a History of my Data I came upon the Change Data Capture Mechanism.  My question now is if there is an easy way to create a lookback query using Change Data Capture, so I could for example query against the database state from 3 Days Ago.  I could do all that with temporary tables but I kind of doubt I'm the first one thinking about this and maybe there's even a built in capability i missed.  Any other way to manage lookback queries is also appreciated :)


How to set Ubuntu to boot first instead of windows 10?

I have installed Ubuntu 16.04 alongside Windows 10, following the steps outlined in .  However, when I boot my computer, it boots to Windows 10 first. I have to go through Change advanced startup options>Use a device and then choose the third "EFI Internal Hard Disk or Solid State Disk"  option.   When I am in Ubuntu, when I type in the terminal   sudo efibootmgr   I get the following results-  BootCurrent: 0002 BootCurrent: 0002 Timeout: 2 seconds BootOrder: 3004,3001,3002,3003,2001,2002,2003 Boot0001* Ubuntu Boot0002* ubuntu Boot0003* Ubuntu Boot0004* Windows Boot Manager Boot2001* USB Drive (UEFI) Boot2002* Internal CD/DVD ROM Drive (UEFI) Boot3001* EFI Internal Hard Disk or Solid State Disk Boot3002* EFI Internal Hard Disk or Solid State Disk Boot3003* EFI Internal Hard Disk or Solid State Disk Boot3004* EFI Internal Hard Disk or Solid State Disk   How do I get make is such that I have the option of choosing between Windows and Ubuntu to boot when I start my computer?   Simple answers will be appreciated!  Edit: The issue is not grub boot order. It is instead UEFI boot order. I have not been able to find a satisfactory resolution to this matter.


I got a VPS running Ubuntu 14.04.5 LTS:  # uname -a Linux host.xyz 3.13.0-042stab123.9 #1 SMP Thu Jun 29 13:01:59 MSK 2017 x86_64 x86_64 x86_64 GNU/Linux   The kernel itself seems to support ext4:  # cat /proc/filesystems nodev   cgroup nodev   devpts nodev   mqueue         ext4 nodev   nfs nodev   nfs4 nodev   delayfs nodev   devtmpfs nodev   sysfs nodev   proc nodev   tmpfs nodev   binfmt_misc nodev   fusectl nodev   fuse nodev   rpc_pipefs   But mkfs does not:  # mkfs. mkfs.bfs     mkfs.cramfs  mkfs.minix   I would like to format a partition as ext4 but apparently, the preinstalled image does not include the required executable. Is there any way to install it? If there is not, what is my best option?


Why doesn't update-manager allow me to upgrade distribution?

I have an Ubuntu 9.04 PC behind a corporate firewall and proxy server.  This requires that in order to get update-manager to fetch and apply updates, I must set the proxy and authentication settings in the Synaptic network configuration.  Once done, I can check for updates and things work smoothly (except I don't get popup notifications of new updates, must manually check periodically).  However, distribution updates just don't show up in update-manager, such as the newly released 9.10 Karmic Koala.  I had the same issue in upgrading 8.10 to 9.04 and solved it by downloading and .  What do I need to do to upgrade to 9.10 using the standard update-manager UI?


L33t Hacking of SE through 404 information leakage

Alternative and much more boring title: Should a 404 result reveal the post title?  I ran across some odd behaviour today. When manually entering a Stack Exchange URL into the address bar1, if you pick a post number that has been deleted then you still see the old post title along with the 404.  For example, I entered:   http://webapps.stackexchange.com/questions/34 and the resolved address came back as http://webapps.stackexchange.com/questions/34/what-is-the-best-empire-avenue-stock-to-buy And http://stackoverflow.com/questions/3 came back as http://stackoverflow.com/questions/1/where-oh-where-did-the-joel-data-go/3#32   Note, I'm obviously not a 10k+ user on either of those sites, which is why they 404'd  It's not that big of a deal, but it seems like this leaks information about the site(s) that we may not want exposed.  And since a picture is worth N words:   Stuff I probably shouldn't be able to see is highlighted.  1And why was I manually entering posts like that? Because I was trying to find a benign 404 example from  that I could share with others because I think their 404 image is hilarious.  2And where did this fabled Joel data go?  Inquiring minds want to know!


How to make references appear on a new page?

I am using the  \documentclass[conference]{IEEEtran} and I want to insert images on full width. For that I am using: \begin{figure}[!htbp] \centering \includegraphics[width=\textwidth]{artworks/pearson-single-dendrogram.png} \caption{Single Linkage Agglomerative Clustering} \label{single-linkage-dendrogram} \end{figure}  But if I print the bibgliography underneath afterwards using \newpage \printbibliography . it appears on top of the figures, rather than from the new page. Does anyone know how this can be fixed?


Disk size much larger than used + available space

After extending my LVM I got a mismatch when using df -kh.   Filesystem              Size  Used Avail Use%  /dev/mapper/Data-Media   11T  5,1T  5,3T  49%   However the usage is correct. Any suggestions on how to fix this?


How the following multiplication table is solved ( related to $F_2[X]/f(x)$ )

$F_2$ is polynomial field of group of integer modulo $2.f(x)$ is $x^2 + x + 1$.   I didn't got how the multiplication is happening in the table.I referred to many sources related to this topic but still i am facing difficulty in understanding it.I will be very thankful if someone explains the concept behind it.


What is going on in this alignat environment?

It was my understanding that the argument of alignat was the number of columns, and that we use & to separate them. I tried the following code: \begin{alignat*}{3}    \quad    & P_{2}(x) &= (2)(2x-1)(x-1)-20x(x-1)+4x(2x-1)\\    \implies & \quad    &= \boxed{-8x^{2}+10x+2} \end{alignat*}  which has three visible columns. However, this doesn't work and produces weird spacings. Tinkering around, I found that the following codes achieves the look I originally wanted (the only difference being the double &&): \begin{alignat*}{3}     \quad    & P_{2}(x) &&= (2)(2x-1)(x-1)-20x(x-1)+4x(2x-1)\\     \implies & \quad    &&= \boxed{-8x^{2}+10x+2.} \end{alignat*}  What am I misunderstanding here?


Why do we fall towards earth and not hover during free fall as per General relativity?

So this is what I understand from General Theory of Relativity: A body freely falling towards earth's surface would be in an inertial frame of reference (air removed) with zero net force acting on it. This would cause weightlessness and would be equivalent to a body in spacetime (under no acceleration) with no gravitational masses around it (and hence no gravity). Any physical experiment in these two frames would thus give equal results making them indistinguishable. But the question is, why is the freely falling body near Earth's surface in motion in inertial frame and not at rest. Why does a ball dropped of the cliff sets in motion and not stay there suspended ? Does the geodesic formed due to spacetime curvature near earth set the ball in motion or is every body on earth having an initial velocity which is maintained once the free fall (and hence inertial frame) begins? But I also know that the body will speed up as it approaches the earth's center of gravity and hence won't remain in uniform motion. Suppose a tunnel is dug diametrically through the surface, the body would perform Simple Harmonic Motion across this tunnel speeding up and down between the tunnel ends. How is the geodesic playing a role in imparting an acceleration which we so call acceleration due to gravity in Newtonian mechanics? Could it be, since the motion of an accelerating body follows a curvature in spacetime, a curvature in spacetime is automatically imparting an acceleration to the body? I'm so confused.


How to execute a script on SSH Login or device bootup/shutdown?

I have a raspberry pi, which is online and connectable by SSH.  What I want to do is create hooks for the following states:   When the device starts Before the device shuts down When an SSH login takes place   This is done as a basic security measure.  My script will simply send a message to various channels, like Slack and Pushbullet, with information like the event that triggered it, current logged-in user and a timestamp.  How do I get my python script to run, when these events take place? I thought about putting it in ~/.bashrc, but that will run the script whenever the profile is sourced.


Unresolved external symbol when use boost TLS

I have problem with error LNK2001: unresolved external symbol.  I have a class CThread split to CThread.h and CThread.cpp  In CThread.h i have included boost/thread/tss.hpp, i have also 2 class:  CThreadLocalStorageSlot and  CThread : public CThreadLocalStorageSlot (derived).  in class CThreadLocalStorageSlot i have:  static boost::thread_specific_ptr ThreadLocalStorage_;  but in linking time i have:  1>CThread.obj : error LNK2001: unresolved external symbol "public: static class boost::thread_specific_ptr CThreadLocalStorageSlot::ThreadLocalStorage_" (?ThreadLocalStorage_@CThreadLocalStorageSlot@threads@2V?$thread_specific_ptr@VCThread@threads@@boost@@A)  Why ? i have included boost file which is responsible for TLS so i have definition of thread_specific_pt.  Any sugestion ?  Best regards


I came across this integral $\int e^{x^n} dx $ and was just wondering how you go about solving it. In this  there approach is to let $y = -x^n$, then $$ dy = -nx^{n-1} dx = -n(-y)^{\frac{n-1}{n}} \ dx \ \Rightarrow \ dx = -\frac{1}{n}(-y)^{\frac{1-n}{n}} \ dy, $$ then sub into the integral, we have $$ \int e^{x^n} dx = \frac{(-1)^{\frac{1}{n}-1}}{n}\int_{-\infty}^\infty  y^{\frac{1}{n}-1} e^{-y} \ dy, $$ then they referenced the primary definition of incomplete gamma function, $$ \Gamma(a,y) = \int_y^\infty t^{a-1} e^{-t} \ dt, $$ and claim that we can write our integral in terms of $\Gamma$ function, and the end result is $$ \int e^{x^n} dx = \frac{(-1)^{\frac{1}{n}-1}}{n} \Gamma(\frac{1}{n}, y). $$ Can anyone fill in the missing step for me? Our integral does look very similar to the gamma function, but what happened to the lower bound of the integral? In our integral the lower bound is $-\infty$; but to equate it to the gamma function we need the lower bound to be $y$.   Anyway substitute back the definition of $y$ we have the final result $$ \int e^{x^n} dx = \frac{(-1)^{\frac{1}{n}-1}}{n} \Gamma(\frac{1}{n}, -x^n). $$ I̶'̶m̶ ̶g̶u̶e̶s̶s̶i̶n̶g̶ ̶t̶h̶e̶i̶r̶ ̶a̶n̶s̶w̶e̶r̶ ̶i̶s̶ ̶c̶o̶r̶r̶e̶c̶t̶ ̶b̶e̶c̶a̶u̶s̶e̶ ̶M̶a̶t̶h̶e̶m̶a̶t̶i̶c̶a̶ ̶a̶l̶s̶o̶ ̶g̶i̶v̶e̶s̶ ̶t̶h̶e̶ ̶s̶a̶m̶e̶ ̶r̶e̶s̶u̶l̶t̶.̶ ̶B̶u̶t̶ ̶a̶n̶o̶t̶h̶e̶r̶ ̶t̶h̶i̶n̶g̶ ̶I̶ ̶d̶o̶n̶'̶t̶ ̶u̶n̶d̶e̶r̶s̶t̶a̶n̶d̶ ̶i̶s̶ ̶w̶h̶y̶ ̶d̶o̶e̶s̶ ̶t̶h̶e̶ ̶i̶n̶t̶e̶g̶r̶a̶l̶ ̶d̶e̶p̶e̶n̶d̶s̶ ̶o̶n̶ ̶$̶x̶$̶?̶ ̶Y̶o̶u̶'̶d̶ ̶t̶h̶i̶n̶k̶ ̶$̶x̶$̶ ̶s̶h̶o̶u̶l̶d̶ ̶b̶e̶ ̶i̶n̶t̶e̶g̶r̶a̶t̶e̶d̶ ̶o̶v̶e̶r̶.̶ Any help is appreciated, thanks.


"Errors were found while checking the disk drive for /." while booting

This is message I get when I turn laptop on, have tried various things but nothing helps. Not an IT wizard so basic instructions to help would be appreciated. Screen reads:  Errors were found while checking the disk drive for /.    Press F to attempt to fix the errors, I to ignore, S to skip mounting or M for manual recovery...   Any ideas please


How can I tell what is opening a file on boot (if not in Startup folder)?

Is there a way to definitively tell what application is attempting to open a file on startup (if it is not in the Startup folder)?  For example, when I boot my PC, I see the following message:    My first step was of course to check the Startup folder. Nothing there (checked hidden files, too).  I've looked through MSCONFIG startup services and none of them are related to the filetype. I've run in Safe Mode and the file does not open, but that still doesn't tell me what is calling the file on startup.  I can open up task manager while the "Windows can't open this file" window is open, but that still doesn't tell me which of the running programs has called it.  I've even tried searching for the file in hopes of deleting it, but every search I've ran for it has turned up nothing.


What are the necessary conditions for a CFT to have a holographic dual?

The number of degrees of freedom of a CFT is given by its central charge $c$. From the bootstrap point of view, any CFT is characterized by the knowledge of its "CFT data", i.e. the scaling dimensions of its operators $\Delta_i$ and its 3-point functions $\lambda_{ijk}$.   My question is, when we say a CFT has a holographic dual, exactly what conditions do we need to impose on the CFT? Does it involve restriction only on the central charge (the repeated meme is large $c$, but large compared to what?), or do we need to fine tune the CFT data also?   Also are these conditions necessary and sufficient for a holographic bulk dual, in the sense that can one always perform a HKLL causal bulk reconstruction starting from such a CFT, or a bulk reconstruction by deriving the Einstein equations via RT formula for these CFTs?


Definite differences between special and general relativity

So I encountered a physics faculty who asked (during a quantum mechanics class) what the difference between special and general relativity is. When I answered that  spacetime in SR is flat while in GR it can be curved, he avoided confirming whether or not my answer was right. Instead he emphasized that SR is inertial while GR is non-inertial. This bugs me as what I've commonly known is that curvature is the difference between SR and GR.  One thing that confuses me about the statement that "SR is inertial while GR is non-inertial" is what exactly it means. Isn't the principle of equivalence (physics laws are the same in inertial frames) consistent in both SR and GR?    Also another thing that I find trouble with is when people say that relativity is the physics of fast moving objects. I've always been under the impression that in relativity, we study physics in a way where time and space are in equal footing.


how to force the image to be placed inline

despit i specified that the image must be place inline "among the text" using [h] command, at run time, the image is place at the end of the section how to set it right?  latex:   \subsection{item1 Vs item2} in this comparison...... ...... ...... ...... \begin{figure}[h] \centering \includegraphics[width=100mm,scale=0.7]{osm_vs_wikipedia_2} \caption{caption} \end{figure}  the rest of the text goes here.. ...


There's this daemon with, for ex. 5 types in one script. Now, i want to be able to start/stop it by specifying the number of the daemon(to start one by one), OR specify "all" (to start in bulk).   The format: (runscript) (commandName) (daemon # or "all")   Need to satisfy two conditions, when the user inputs:  (1) correctly (either by number or "all) OR  (2) incorrectly (either inputted num is greater than $count or all other string than "all"). All conditions are already achieved except for one, if the user inputs other string than "all"   Sample code:  case 'startDaemon': #commandName set count = 5  if ($#argv == 2 && $2 == all) then     echo "correct, do this" else if ($#argv == 2 && $2 < $count) then     echo "correct too, do this" else if ($#argv == 2 && ($2 != all || $2 >= $count)) then     echo "Incorrect parameter: specify daemon # less than $count or 'all' to start all." else      echo "Please use: $0(runscript) $1(commandname) (daemon # or all)"   whenever I type: (runscript) startDaemon hello, for example, error shows:  if: Expression syntax   When it should have gone to the 3rd condition.   PS. Im using csh. The script given to me is in csh.


Why do I get an error when using cd as env's utility argument?

I'm studying the env command and trying to understand how it works. Here's the command synopsis: env [-iv] [-P altpath] [-S string] [-u name] [name=value ...] [utility [argument ...]] I decided to play around with it and tried: env cd /home/username I get: env: ‘cd’: No such file or directory The result is the same with either env cd ~ or env cd. So why do I get an error when using cd as env's utility argument?


Changing threshold in logistic regression

Suppose that you have a logistic model and the predicted probabilities of a $1$ all are in $[0.2,0.3]$. So the predictions would be "0" based on a threshold of $0.5$. What would be a good threshold to choose?


Old version of google-chrome starts even if newer is installed

For a while I haven't received Chrome updates on Kubuntu 16.04 64-bit . I did everything written here   When I execute  sudo apt-get install google-chrome-stable   it writes  google-chrome-stable is already the newest version (56.0.2924.87-1).   but when I start chrome using  google-chrome-stable   the about:version page says  Google Chrome   49.0.2623.108 (Official Build) (64-bit)   Why is this?


Flat not projective, projective not free

I am looking for examples of a flat but not projective module, and of a projective but not free module.


Show that no integer of the form $a^3 +1$ is a prime for $a>1$

Can someone please solve this and explain the steps taken to reach this solution ?


In Game of Thrones, is it possible for Danaerys's child to still be alive?

Was Daenerys' baby pronounced dead or was the body seen when it was dead? Also how does anyone that the body was Daenerys' baby? Couldn't the mid-wife have taken Daenerys' baby for her own or sold it and pretended that it died? If answered please give evidence, I already read the wikia, it didn't have a satisfactory answer.  Is there any canon evidence that either suggests that this is possible, or shows that this cannot be the case?


Difference between "var" and "object" in C#

Is the var type an equivalent to Variant in VB? When object can accept any datatype, what is the difference between those two?


Can someone give me an example of an operator $T:X \rightarrow Y$ such that, $\\$ $$||T|| \ne max_{||x|| \leq 1} ||Tx||_{y}$$


I have an HP pendrive of 16GB. One day my little brother tried to make a bootable Hackintosh using that pendrive and we had a power cut when the write process was going on (my brother was using Mac OS X 10.6 (Snow Leopard) hackintosh).  After that happened, I tried to format it with  but it gave me the following error message below; Is there a way to fix this  pendrive?


confidence intervals in linear regression

I am trying to understand the confidence interval for linear regression parameters. At this link  an answer is provided. However, I did not understand in the derivation fully. Do we consider the regression parameters as random variables?   That is what are the random variables in the following regression: $$ y=\beta_1 x+\beta_0 + \epsilon $$ From what I understand is that just the $\epsilon$ is random variable with mean 0 and variance $\sigma^2$. Considering $\beta_1, x, \beta_0$ as constants $y$ also becomes random variable with mean $\beta_1 x+\beta_0$ and variance  $\sigma^2$, from which confidence interval can be calculated.  However,for regression coefficients confidence intervals are also calculated. Can you please clarify the random variables in regression please?  Thanks.


What is the nonlinear transformation assumed by the gaussian (rbf) kernel?

A common kernel choice is the gaussian kernel: $ k(x,x^{'}) = \exp \big( -\frac{1}{2\sigma^2}\| x - x^{'} \|^2 \big)$  This implies a transformation on $x$, and equally on $x^{'}$. What is it?


Can i turn on usb debugging without touching the screen?

My phone working for a long time without problems. I go to sleep my phone is still working.I wake up and turn on my phone. The phone turned up but i can't write my PIN and my screen is almost not working. I thing the problem is with android and i don't know how to get in recovery mode to factory reset or installing new rom. I don't have turned on usb debugging .Is there a way to get usb debugging turn on without touching the screen ?


I got two conditional offers for postgradute courses from two universities. The English requirements are a bit lower for one university (IELTS 6 with 5.5 in each section) than for the other (IELTS 6.5 with 6 in each section).  Since I will know my IELTS results next month at the earliest, I do not know which offer I should accept because I have to decide by the end of this month.  Is it acceptable to accept both offers? I am fine with paying the deposit or other fees even if they are unrefundable.


Does undying triggers an addition of counter?

When a creature with undying comes back on the battlefield, does it get a +1/+1 counter or is the counter already on it?  For example: I have a , a  and an . My Geist is destroyed and comes back "with" a +1/+1 counter on it, does the counter is "placed" so it triggers Hardened Scale or Animation Module?  EDIT  There is an ambiguity on counters that are placed and cards that come with the counter already on it... are they "placed" anyway?  Does  behaves as a replacement effect like  and do they cumulate?  Does  +1/+1 initial counters behaves like on undying?


Example of an interesting topological space that doesn't have a metric

I've started studying topology, and the impression I get is that it's all about studying spaces without using a metric. So we have to talk about these open sets instead. So basically a topological space is a generalization of a metric space.  What I haven't been able to find, though, is any example of a space I would be interested in that doesn't have a metric! I'm not looking for general "applications of topology", I'm looking for a specific non-metric topological space that is interesting outside of topology, that doesn't have a metric. Preferably as simple as possible; i.e. ideally you should be able to just write it as a set comprehension. But any interesting spaces without metrics qualify.


Calculate the difference between time and current time in minute

my question is about a field in my table that save time in format like "06:00 PM"(just show time without date with AM/PM). I want to change saved time that has not AM/PM then calculate difference time betwen that time and current time in minute, then if diference is between 60 minute echo something. for example some thing like this $time =date("G:i", strtotime($Time_Field)); $time=strtotime($time); $currentTime = time(); // current time $difference = $currentTime - $time; if( $difference > 0 && $difference < 60 ) { echo " your request is begin in next 1 houre "; }  My variable output is always zero even if the time interval is more than 59 minutes i test below  and this  But I was not able to calculate the difference between the time stored in the database and the current time in minutes. Thank you for your guidance


java.lang.NullPointerException while calling a bean readonly property

I have started learning JSF recently I'm working on a JSF page along with a managed bean. now I'm trying to attach ajax functionality to my code but I'm facing a problem of null pointer exception. This is my index.xhtml <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"            "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  <h:head>   <title>Student Registration Form</title> </h:head>  <h:body>
Please enter user name and password
          <h:form prependId="false">         Username: <h:inputText id="username" value="#{student.username}" />

                  Password: <h:inputSecret id="password" value="#{student.password}" />

                  <h:commandButton value="Login">             <f:ajax execute="username password" render="out" />         </h:commandButton>                  <h:outputText id="out" value="#{student.greeting}"/>                       </h:form>  </h:body>    This is the Java code for the bean class package com.ahmed.jsf.Studen_Registration;  import javax.faces.bean.ManagedBean;  @ManagedBean public class Student {          private String username, Password;          public Student() {}      public String getUsername() {         return username;     }      public void setUsername(String username) {         this.username = username;     }      public String getPassword() {         return Password;     }      public void setPassword(String username) {         this.Password = username;     }     public String getGreeting() {         if(username.length() == 0) return "";         else return "Welcome to JSF 2.0 + AJAX" + username + "!";     } }  everything was working before adding the getGreeting function and the stacktrace states that the NullPointerException is coming from the getGreeting function


Can we bound adversarial power in terms of total entropy in universe?

The strengths of various cryptographic primitives are often explained (though not defined) in terms of how long it would take to break under the current best known attacks. For example, apparently the best known attack against AES-128 reduces it to ~126 bits of security, and that is often explained as "good enough" because even if one were to use all the world's computers together it would still take hundreds of years to break a single key. Assuming (perhaps ridiculously) for the purpose of this question that the current best known attack against some algorithm is actually the best possible attack, this still doesn't seem like quite enough because what if we develop new technologies that let us try combinations faster?  Perhaps this is a ridiculous idea, but for peace of mind it would be nice to know that no one could ever break my ciphertexts (under current best known methods). As far as I can tell, there is only one fundamental limit to the ability to "just try combinations faster," and that's Landauer's principle. According to Wikipedia, Landauer argued that the minimum possible energy required to erase one bit is $kT ln(2)$ where $T$ is the temperature in Kelvin and $k$ is the Boltzman constant. I would like to compare this to the . According to the linked paper, this is estimated at $\sim 10^{105}k$, although the entropy of the cosmic event horizon is bigger, estimated at $\sim 10^{122} k$, and I don't know nearly enough physics to know what that means so I'm going to use the bigger one.  So it seems, naively, like we should be able to get the total number of possible bit erasures before the universe runs out of entropy, $N$, with the simple equation $NkT ln(2) \leq 10^{122}k$ and get $N \approx 10^{122}$ (assuming that $T \approx 2.7$ due to cosmic background radiation).   Now assume that we have some hash function $H$ that is assumed to have $n$ bits of security under either classical or quantum attack. As far as I understand, this means you have to do at least as much work as running the hash function $2^n$ times. It appears that . As such, it seems safe to assume that you must use at least one bit of entropy (or equally erase one bit of information) per run of the hash function, for a total of at least $2^n$ bits. If we let $2^n \gt N \approx 10^{122}$, we get $n \gt \sim 405$, and seem to show that under the security assumption, it is impossible to break $H$ within the life of the universe if $n$ is greater than, for good measure, 410.  So, finally, my question is this: is this analysis correct? Can we really bound entropy consumed based on the "hardness" of the cryptographic problem? (Obviously, it would be off-topic here to talk about the details of the physics behind the problem.)


My lecture notes state that an 'easy' result is     If $R$ is an integral domain then an irreducible element of $R$ remains irreducible in $R[x]$, and the units in $R$ and in $R[x]$ are the same.   I can't seem to get my head around why this is the case, and what a unit in $R[x]$ means intuitively because I don't see how the units can be the same if $R$ is the coefficients of the polynomials in $R[x]$. I.e. for an unit say $\alpha \in R$ then what is the 'corresponding' unit in $R[x]$? I is it $\alpha x$ or $\alpha x^2$... or am I getting the wrong end of the stick here?


What exactly does a tag need to be up for burnination ? I feel kind of trapped every time I make those requests because of of this problem :   Not enough good question with the tag so let's just edit and let the tag delete itself Too many question asked with that tag so burninating might cause a lot of mistagged questions   When is a tag ready to go away ?


In Return of the Jedi, the ewoks plan on eating Luke, Han and Chewie.     THREEPIO: I'm rather embarrassed, General Solo, but it appears you are to be the main course at a banquet in my honor.   At this point, the tribe had already met and befriended Leia, and had encountered the Imperials in the past, making it fairly likely that they knew humans were .  This raises the question of how often they ate sentients. Was it a one-off thing, to honor an extremely rare visit from a god, or was this fairly common?


Nginx: How To Completely Disable Request Body Buffering

I'm trying to set up  on my Ubuntu box and have Nginx run in front of it. Problem is, I keep getting this warning when I try to upload stuff through the web interface:  31115#0: *14 a client request body is buffered to a temporary file   This also explains why progress bars on the upload window doesn't work. Here's my relevant Nginx configuration:      # proxy the madsonic server here     location / {             proxy_pass                      https://madsonic-server/;             proxy_redirect                  off;             proxy_buffering                 off;             proxy_request_buffering         off;             allow                           all;             proxy_http_version              1.1;              proxy_set_header                Host $http_host;             proxy_set_header                X-Real-IP $remote_addr;             proxy_set_header                X-Forwarded-For $proxy_add_x_forwarded_for;             proxy_set_header                X-Forwarded-Host $server_name;             proxy_set_header                X-Forwarded-Proto $scheme;              client_body_buffer_size         0;             client_max_body_size            0;             proxy_max_temp_file_size        0;             proxy_read_timeout              18000;             proxy_send_timeout              18000;              gzip                            off;     }   I'm using Nginx 1.9.12 at the moment.  What I'd like to achieve is to make Nginx not use request body buffers at all and just pass the request body directly to Madsonic, regardless of size. Is this even possible? If it is, what would be the correct configuration?  Other questions seem to get answered with ways to set the buffer sizes. I don't want any buffers. I want to directly pass the request body to Madsonic.


I have been trawling Google for some time and am failing to find an answer to my question:  What's the best way to allow users to access my entire SharePoint 2013 site/farm from outside of our corporate network??  Is it really as simple as pointing the firewall to port 443 of the WFE?   UAG seems to be on the way out and I don't want to use the publishing features...HELP!


Learning C++ with Programming Principles and Practice Using c++, I done this   #include "../../../std_lib_facilities.h" using namespace std;   int main() {     cout << "Hello programming!\n";     return 0; }   First I got warning with "PDB files not found" after debugging. Then I solved that, and getting this,  'FLTK testing.exe' (Win32): Loaded 'C:\Users\Chai\Documents\Visual Studio 2013\Projects\FLTK testing\Debug\FLTK testing.exe'. Symbols loaded. 'FLTK testing.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ntdll.dll'. Symbols loaded. 'FLTK testing.exe' (Win32): Loaded 'C:\Windows\SysWOW64\kernel32.dll'. Symbols loaded. 'FLTK testing.exe' (Win32): Loaded 'C:\Windows\SysWOW64\KernelBase.dll'. Symbols loaded. 'FLTK testing.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcp120d.dll'. Symbols loaded. 'FLTK testing.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcr120.dll'. Symbols loaded. 'FLTK testing.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcr120d.dll'. Symbols loaded. The program '[7320] FLTK testing.exe' has exited with code 0 (0x0).   But I'm still not getting the output showing "Hello programming!". I have tried cin.get() too but no result. Any advice??


Assumption made for the WKB approximation in radial coordinates

I was thinking the other day, if you had the Schrodinger equation in 3-dimensions, and had a spherically symmetrical potential. Ie.: $$-\frac{ℏ^{2}}{2m}∇^{2}ψ+V(r)ψ=Eψ$$ Then you could simplify the Laplacian to: $$-\frac{ℏ^{2}}{2m}\frac{1}{r^{2}}\frac{∂}{∂r}\left(r^{2}\frac{∂ψ}{∂r}\right)+V(r)ψ(r)=Eψ(r)$$ The solution to this equation, doesn't correspond to the WKB solution, which if I recall correctly, is: $$\frac{A}{\sqrt{p\left(r\right)}}e^{\left(\frac{i}{ℏ}\int_{ }^{ }p\left(r\right)\ dr\right)}$$ Unless, you somehow remove the first-order term that turns up in the Laplacian - which I vaguely remember somewhere that you take the limit as $r$ approaches infinity. I don't know if this is what is suppose to be done, but if it is, then how is it viable? And if not, then could someone please explain how to solve this discrepancy. Edit: I want the states to also be spherically symmetrical. EDIT: I think I've found the solution, I made the substitution $$\frac{w\left(r\right)}{r}=ψ\left(r\right)$$ I then substituted this into the previous radial equation, and it gave me the regular TISE in 1 dimensions. This ultimately yields the WKB solution for ψ, which is : $$ψ\left(r\right)=\frac{1}{r}\frac{A}{\sqrt{p\left(r\right)}}e^{\left(\frac{i}{ℏ}\int_{ }^{ }p\left(r\right)\ dr\right)}$$


Let $S = \{A : A \subseteq \mathbb{Z}^+, |A| < \infty\}$. Prove or disprove $|S| = |\mathbb{Z}|$.

If it were $\mathbb{R}$ instead of $\mathbb{Z}$, I could figure it out: just construct $2$ bijections.  For example, map $\mathbb{R}$ to $(0,1)$ and then map $(0,1)$ to $\mathbb{R}$ in tangent function. However, when it comes to a set with discrete elements, this method doesn't work.  Is there any other ways?


Question regarding one-point compactification and homeomorphisms

Say $X^{*}$ represents the one-point compactification of a space $X$ that is locally compact, non-compact, and Hausdorff. Also suppose that $Y$ is compact Hausdorff and $Y-\{p\}$, for a single point $p$, is homeomorphic to $X$. So then would $Y$ be homeomorphic to $X^{*}$? I think it is, but I'm not sure how it can be shown.    My attempt so far: Correct me if I'm wrong, but I started with inclusions $i: X \rightarrow X^{*}$ and $j: Y-\{p\} \rightarrow Y$, along with the homeomorphism $h: X \rightarrow Y-\{p\}$. So we need to find a homeomorphism $g: X^{*} \rightarrow Y$. So I tried using a commutative diagram and so far, I've concluded that $g$ (if it is to exist) would have to be continuous since the continuous image of a compact space is compact (I think this follows from $X^{*}$ being compact), but then one of my inclusions, i.e. $i$, can't possibly be continuous, can it (since $X$ is not compact)? How can this be fixed?


Trailing characters stripped from titles bypass length minimum

Test to see if the title length requirement can be circumvented by appending lots of dots.


Structuring game world entities and their rendering objects

I'm putting together a simple 2d tile-based game.  I'm finding myself spinning circles on some design decisions, and I think I'm in danger of over-engineering.  After all, the game is simple enough that I had a working prototype inside of four hours with fewer than ten classes, it just wasn't scalable or flexible enough for a polished game.  My question is about how to structure flow of control between game entity objects and their rendering objects.  Should each renderer have a reference to their entity or vice-versa?  Or both?  Should the entity be in control of calling the render() method, or be completely oblivious?  I know there are several valid approaches here, but I'm kind of feeling decision paralysis.  What are the pros and cons of each approach?


My Minecraft server gives me two of these messages a second (probably from a friend's mischief)...  [15:23:51 INFO]: [@: The entity UUID provided is in an invalid format]   I disable command blocks in server.properties and it stops. But I'm pretty sure it will come back when I re-enable it. How do I ferret out the offending thing and stop/delete it (preferably from the server console)?  It's not telling me what/where it is.  Do I have to nuke and pave the entire world?  Or is it harmless except for the message? Should I just disable the output and let it go?


Permissions not extended to user in minecraft group

I have a directory, under /srv:  drwxrwxr-x  3 minecraft minecraft 4096 Dec 30 06:23 minecraft  Owned by user minecraft, group minecraft. Group has read/write/search permissions. I have a user, shelvacu, that is part of the minecraft group:  $ groups shelvacu shelvacu : shelvacu sudo minecraft   And, as shelvacu, I run mkdir /srv/minecraft/testdir:  $ mkdir /srv/minecraft/testdir mkdir: cannot create directory ‘/srv/minecraft/testdir’: Permission denied   Why? The minecraft group has write permission on the directory, and shelvacu is part of the minecraft group. What am I missing?


Is it possible to add a button outside of a panel, e.g. in the user-preferences? Say I want to add a new addon category in the addon list, via an addon:    Is this possible? How?


checking port for availability before creating DatagramSocket

This question is about datagram socket not tcp sockets, so please review it first before thinking its duplicate Is there a way to check the port before creating a new DatagramSocket. When the port is in use for example by another instance the code below throws SocketException      socket = new DatagramSocket(4446);   I would like to have it checked before I create the DatagramSocket object. So that if it is not available I can increment it and check again untill it becomes available and then I create the Socket ?


I need to get  string array from string line. It is possible ?  main(){  string x = "This is string";   //do something, function or... i don't know...  //result   cout << string[0] << string[1] << string[2] << endl;   //cout << "This" << "is" << "string" << endl; }   How to do this array ??! Ty ;)


Is my HDD to SSD cloning method technically correct?

I have an HP laptop with planned HDD to SSD migration with Windows 8 installed.   Source - HDD - 500GB - SATA - I can put this in my server and save it to a file. Destination - SSD - 120GB - M.2 - I can't put this into my server.   I plan on doing the following in a few days:   Delete the two HP partitions at the end of the disk. Shrink the system (C:) partition using some software for Windows below 100GB. Using Linux computer and pv utility as follows:  pv < /dev/sourceDrive > /dev/destinationDrive   Making 1:1 copy of the drive.  Expecting it to fail of course at the end of the SSD drive, i.e. at 120 GB. But since there will be no data on the source disk there, that is no problem, right?   That's about it. Is it a sound idea?


How to prove that $\lim_{(x,y) \to (0,0)} \dfrac{x^3y}{x^4+y^2} = 0?$   First I tried to contradict by using $y = mx$ , but I found that the limit exists.  Secondly I tried to use polar coordinates, $x =  \cos\theta $ and $y = \sin\theta$,  And failed .. How would you prove this limit equals $0$?


How to get a vertical bar which is longer than \mid ?

sometimes when writing mathematical expression with partial derivatives, one needs to write a vertical bar afterwards and write the value at the which the partial derivatives are being computed as subscripts. See for example the bottom post here:    However, the \mid symbol doesn't produce a tall bar that corresponds to the size of the partial derivatives term. Is there a way to have a taller bar?   PS: Some other posts here mention \middle| but this doesn't compile on my computer.  Thanks in advance....


How to write virtually aligned superscript and subscript

I have this line: \textbf{Adv}\textsuperscript{downgrade}\textsubscript{$Pi$, DP, X}  But I get this output:  And I want it like this:  Can you help me with simple solutions as much as possible plz.


Using MAX in SQL Expression of ArcMap ModelBuilder

I am trying to use a SQL expression in order to select values that are >= 25% of its max value in that column. For instance, VALUE >= MAX(VALUE)*0.25, and those will ultimately be the selected points it pulls out.   Is there syntax to make that happen, or am I going to need to create a new column and use field calculator on it?   Biggest issue with that is I will have to do this for about 250 files. I am also trying to create this in ModelBuilder.  When I try it as above it just returns that there is an error with the expression.


I have a boolean for the status of a page on whether it is new or not. If it's selected, I want the following code to take effect.    {% if fields.field_new.content %}   <div class="info--details__new">     {{ fields.field_new.content }}   </div> {% endif %}   This works fine for when it's selected. However, if I unselect it, it still displays the div with the info--details__new class only empty.  I'd like for this div to not be displayed when this boolean isn't selected but can't seem to figure out how to do this in my twig template.  What's the best way to go about doing this so that my empty div doesn't show up when the boolean is unselected?  This is in my views-view-fields--VIEW-NAME.html.twig file.


How to render a background image in 2.8?

I'm trying to "add" an 3D object onto a photo. I have added the photo to the scene in three ways so far, but none of them render (eevee):   Camera > Background Images Empty a. Add > Empty > Image (Empty gets added to current Collection) b. Add > Image > Backround (Empty gets added to Scene Collection)   These all show up in the 3D View and I was able to align the camera and the object so its perspective matches the scene in the photograph. But when I Render the scene, I only see the object, not the background image.  For the latter, it's simple: Empties are not rendered at all. There are few questions about this, since 2.8 has changed how it handles background images. The most popular seems this one (it includes references to others):      But I seem not to be able to find a method to have the background image render.  Another method might be to use the Compositor (Nodes) to Mix or Alpha Over an Image with the Render Layers. But this does not give the same alignment as achieved with the background image (also this requires that the World background does not get rendered (Alpha channel); for Eevee, this can be achieved by checking Film>Transparent).  What other options are there?  Docs:


How to make NVIDIA GeForce 680m default graphics card instead of Intel HD Graphics 4000? (Alienware M17 Laptop)

I believe that the question title describes it all... but I just bought 2 brand new 2560x1440 monitors and I need to make use of my NVIDIA GeForce 680m card instead of the Intel HD Graphics 4000 card. Can anyone point me in the right direction?


this is my first post on tex exchange , i am using latex for the first time for my internship report . I read that lateX is very useful and professionnal especially for writing equation . I've found a lot of Books about it but i'm not fan of them ... i was wondering if there is a method , steps or structure to follow to make a good report  thanks


$$\sum\limits_{n=0}^{\infty} \frac{x^{3n}}{(3n)!}$$ should be calculated using complex numbers  I think, the Wolfram answer is :  $  \frac{1}{3} (e^x + 2 e^{-x/2} \cos(\frac{\sqrt{3}x}{2})) $  How to approach this problem?


How does Zonal statistics handle pixels that are on border of polygon?

I am using the plugin zonal statistics to calculate the sum of the raster cells within  polygons. How does this plugin handle pixels that are on the border of the polygon, are those cell values included in the statistics?  I am using QGIS 1.8.0.


What is another way to say "Mature in thinking"

So my sentence is      X has showed me a maturity in thinking beyond his age.    However, I find it very weird. Do we have another way to say the sentence ?


I am applying for student resident card for a university in Finland.    Before reaching Finland for my studies, I first plan to visit Germany.    Is it okay to first travel to Germany and then proceed for Finland on the same student resident permit?


Section in page header and TOC without number and no indention

I'm looking for advise about handling sections a a special way. What I want:   Sections should not be numbered, they should be listed in the TOC and be available in the page header, and they should have not left indention.   A very much abridged version of what I'm currently trying is this:  \documentclass{book}  % No section numbers. \renewcommand{\thesection}{}  \begin{document}  \tableofcontents  \chapter{Foo}  % This section should be in the TOC and the page header. \section{Bar}  Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.   \end{document}   Unfortunately this does not produce the desired result. 1. and 2 work but 3. doesn't: the section titles have a left indention in the text.  How can I make all three requirenments work at the same time?


I have a script that will try to extract the file's base name and then I do additional work with it. Only when using this script with a file with this naming convention (including spaces and characters - not really sure what's triggering the error), do I get the basename extra operand error.   The file name: JERASH - XZ 837367432.pdf  Here the script once executed generates error:  filetimestamp=$(date "+%F-%T") timenow=$(date -u)      for file in files/input/*     do       printf "Break 1 \n"       #filename no extension:      filenamenopath=$(basename $file)      filenamenoext=${filenamenopath%.pdf}      printf "Break 2 \n"      #check if file is pdf       printf "File Name with No Path:" $filenamenopath      printf "Break 3 \n"   And here is the error:     Break 1  basename: extra operand ‘XZ’


I want to add to my LaTeX document ( [book] ) the cover of the first page. I have a problem though. It does not cover the entire page.  Here is the photo I want to add:    I use the geometry package with this configuration:  \usepackage[margin=1.5cm , a4paper]{geometry}   and as a command to include the picture I use:  \centerline{\includegraphics[scale=1.1]{cover_photo_new_version.jpg}  }   Well, the output is not the expected. This is what I get when I compile the document     and as we can all see it does not cover the page. I have read many questions here in TEX.SE but none of them fix my problem. Any way to fix it?


What causes Google to display a search result with a list of articles below

We have a web application on which users have profile pages that have a few details about the user, and then a list of blog posts that user has created. We're finding that in some circumstances Google will display a search result for one of these pages with the posts listed below like this:      In other circumstances, we have profile pages structured in exactly the same way but it is not displayed in the same way on Google search results. Like this:      I am trying to work out why the two pages are being displayed differently in the search results. The main difference is that they are on different domains, so my current thinking is that perhaps Google categorises domains in some way, and perhaps displays results differently because of that.  If anyone is able to tell me why this might be happening, or has any ideas, it would be much appreciated.     - the question does not answer my question about why two pages which have exactly the same markup and structure but just different content are displayed differently in search results.


Prove that $ex \leq e^x$ for all $x \in \mathbb{R}$

This is easy to prove for negative $x$ but what about positive $x$? Should I use MVT?


A potential supervisor is greeting me with "Hi" followed by my first name. How should I greet him in return? If I say "Hi" followed by "Dr." and his last name, this will look awkward. If I say "Hello" followed by "Dr." and his last name, this will look more formal than his original greeting, and might look like a sign of my trying to distance myself. So how can I keep being formal yet not look awkward or "cold"?


What is the formal process for a theory to get accepted by the science community?

Question description so that anyone can evaluate and answer accordingly Since last many years, I have self-studied a subject that is Theoretical Physics - Cosmology, Time and Space. I have never got the opportunity to study this at University level so I self-published a book on the theory which I have researched. I don't know what is the formal process for a theory to get accepted by the science community, please guide me on how to proceed further? The link provided in the comment section is different as it was more about publishing a paper in a science journal... However, I got an answer below that there is no formal process and there are options of publishing a paper in a reputed journal or participating in the conference... I am looking for more options if possible.


Documents needed to cross US border and back again into Canada on the same day if no passport is available

My daughter and I will be traveling from Canada to the US for a one-day lacrosse game on Saturday.  Her passport is in the process of being renewed. Will she be OK to cross the border into the US and back again into Canada with a government-issued license and a birth certificate?


Site logo issue in international Stack Overflow site's profile page for anonymous users

In the international Stack Overflow sites for logged-out users, when navigating to a specific user's profile in the top bar the partial text is truncated.  For an example in Russian Stack Overflow Community user profile, the text "на русском" is partially hide in the top bar. For the remaining page the logo is displaying properly.   Seems in other pages the HTML tag as Stack Overflow на русском, where as in the profile page the _glyph class is missing, which has the height attribute.  The issue can be reproduced in other site's community user profile too.                                  System configuration:  OS: Windows 10 Mozilla Firefox: 66.0 (64-bit) Google Chrome: Version 72.0.3626.119 (Official Build) (64-bit) Microsoft Edge: 41.16299.15.0 Zoom: 100%


When using sed to replace strings in-place, is there a way to make it report the changes it does (without relying on a diff of old and new files)?  For instance, how can I change the command line  find . -type f | xargs sed -i 's/abc/def/g'   so I can see the changes that are made on the fly?


What happens if I add a infinite sheet of a perfect conductor in a constant applied magnetic field perpendicular to the surface? e.g. I have a sheet in the x-y plane and I apply $B_0 \hat{\mathbf{z}}$. What will the scalar potential become apart from the $-B_0 z$ term?


This is my script:  load_1=15231 load_2=20547 load_3=24561 load_4=22874 f4=434     sum_1=`expr $load_1 + $f4`    sum_2=`expr $load_2 + $f4`    sum_3=`expr $load_3 + $f4`    sum_4=`expr $load_4 + $f4`     min=$sum_1    LIST1="1 2 3 4"    for x in $LIST1     do      if [ $sum_$x -lt $min ]       then        min=$sum_$x        f3=$x      fi     done    echo $min    echo $f3   below is the output while executing the script using bash -x:  + load_1=15231 + load_2=20547 + load_3=24561 + load_4=22874 + f4=434 ++ expr 15231 + 434 + sum_1=15665 ++ expr 20547 + 434 + sum_2=20981 ++ expr 24561 + 434 + sum_3=24995 ++ expr 22874 + 434 + sum_4=23308 + min=15665 + LIST1='1 2 3 4' + for x in '$LIST1' + [[ 1 -lt 15665 ]] + min=1 + f3=1 + for x in '$LIST1' + [[ 2 -lt 1 ]] + for x in '$LIST1' + [[ 3 -lt 1 ]] + for x in '$LIST1' + [[ 4 -lt 1 ]] + echo 1 1 + echo 1 1   the value of loop variable 'x' has to be substituted in the test condition variable sum_x and then value of $sum_x has to be given to the test condition. But as shown in the output, the value of 'x' is directly taken in the condition. I have tried various combinations of quotes and paranthesis but nothing worked for me. Please help!!


How to save a file in photoshop that is supposed to be displayed on a web site?

I just have made an ad banner in photoshop (width 1000px, height 250px) and sent it to the developer, but after an hour he said that the file that I have sent to him opens very slowly because it weights too much (it was saved in PNG and weighed 600KB)  After that I resaved it in JPEG, with medium size and it started weighing 80KB, but the developer said that when he puts it on the web site, it loses the quality and he can see the pixels.  What can be done to resolve this problem?


How to find the midpoint between $2$ geographic coordinates (latitude, longitude)?

I have 2 geographic coordinates that I would like to find the midpoint to. For example:  Coordinate 1: $-37.756154,\ 145.147506$  Coordinate 2: $-37.754339, \ 145.143986$  After searching the internet and testing multiple functions, it seems like this is incredible difficult task.  Is there a function that can provide an accurate midpoint between $2$ coordinates with consistency across the globe or is it not possible?  EDIT: If there is an answer I would prefer it in programmatic syntax if possible:  fun midGeoPoint(lat1, lon1, lat2, lon2): GeoPoint {      val dLon = Math.toRadians(lon2 - lon1)      //convert to radians     lat1 = Math.toRadians(lat1)     lat2 = Math.toRadians(lat2)     lon1 = Math.toRadians(lon1)      val Bx = Math.cos(lat2) * Math.cos(dLon)     val By = Math.cos(lat2) * Math.sin(dLon)     val lat3 =     Math.atan2(Math.sin(lat1) + Math.sin(lat2), Math.sqrt((Math.cos(lat1) + Bx) * (Math.cos(lat1) + Bx) + By * By))     val lon3 = lon1 + Math.atan2(By, Math.cos(lat1) + Bx)      return lat3, lon3 }


Where's the iMessage contact icon stored?

Where is this empty avatar    stored on  macOS Catalina?


How do I set it so that my computer won't go into auto-standby/sleep mode while Opera is downloading?

How do I set it so that my computer (OS is Windows 7) won't go into auto-standby/sleep mode while Opera is downloading a file? (Without disabling Windows' auto-standby/sleep setting.)  I'm thinking of enabling a functionality similar to uTorrent's 'prevent standby if there are active torrents' option, if there is one.


Android - Why calling this function directly instead of onClick causes a NullPointerException?

I am trying to integrate the  in my project and I wanted to remove the Login button, i.e. such that the Activity switches to the next activity without the user having to click the Login button. For this, I removed the code for setOnClickListener for the mLoginButton and instead, directly called the loginClicked() function, which was previously being called from the onClick() method. But this causes NullPointerException: Attempt to invoke virtual method 'boolean com.example.yankee.cw.SinchService$SinchServiceInterface.isStarted()' on a null object reference. These are the only changes I made to the code:  @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.login);          mLoginName = (EditText) findViewById(R.id.loginName);          mLoginButton = (Button) findViewById(R.id.loginButton);         mLoginButton.setEnabled(false); //        mLoginButton.setOnClickListener(new OnClickListener() { //            @Override //            public void onClick(View v) { //                loginClicked(); //            } //        });         loginClicked();     }   And earlier it was like this:    @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.login);          mLoginName = (EditText) findViewById(R.id.loginName);          mLoginButton = (Button) findViewById(R.id.loginButton);         mLoginButton.setEnabled(false);         mLoginButton.setOnClickListener(new OnClickListener() {             @Override             public void onClick(View v) {                 loginClicked();             }         });     }     Why doesn't this work and gives the NullPointerException instead ?    Edit:


Why won't Photoshop Elements recognize my Nikon D7000 raw files?

How can I import a file into Adobe Elements from a Nikon D7000 when the file format is NEF and it tells me I'm using the wrong file type?


Definition of a Euclidean Domain: how to show that the condition $f(ab)\ge f(a)$ is actually not necessary?

Quoted from .     We called an integral domain $R$ a Euclidean domain if there exists a function $f$ from $R$ to strictly positive integers such that:   1) For $a,b$ non zero in $R$, $f(ab)\ge f(a)$.   2) If $a,b\in R$, $b\neq 0$, then we can write $a=bq+r$ with $q,r\in R$ such that either $r=0$ or $f(r)<f(b)$.     One of the answers below say that the definition is equivalent if we remove 1) above. To prove this, we take  $$ g(a)=\min_{x\in R^* a} f(x), R^*=R\backslash \{0\}. $$  Obviously $g$ satisfies 1). Now I am struggling to show that the new function $g$ satisfy 2), given that $f$ satisfies 2). Any hints?


How to flash an ISO for Ubuntu installation to a flash drive using Mac OS X 10.6

I need to flash a Ubuntu ISO image to my flash drive, but I'm running OS X 10.6, which isn't supported by Etcher. Is there any way to do this?  (I'm going to flash the lubuntu ISO, specifically.)


A map between metric spaces preserving convergent sequences is continuous

Pugh, "Mathematical Analysis", exercise 2.17:     Assume $f : M \to N$ is a map from one metric space to another which satisfies the following condition: for every convergent sequence $(a_n) \subset M$, the sequence $(f(a_n)) \subset N$ converges. Prove that $f$ is continuous.   (I know that if $f$ commutes with limits then the answer is affirmative, but I can't prove it with that hypothesis).


Should I leave my UV filter on permanently?

I got into the habit of buying off-the-shelf UV filters early on, and I've stuck to it. My M. Zuiko 'kit' lenses always have their UV filters fitted, except when I want to use something else like an ND or a circular polariser. I do this to protect the glass on the lens from dust, moisture and scratches. I'm now finding myself looking for a 46mm filter for a prime lens, which leads me here to confirm my habit is healthy. The Hoya filter I'm looking at says "Keep the filter attached to the lens to use as lens protection", but there must be circumstances where I'd get a better picture with it removed. Is this a bad habit, which I need to kick?


Android: Non-static method cannot be referenced from static context. Confused?

I am extremely extremely new to Java and programming in general. I wrote this for a basic program to add 2 numbers input by the user and add them up and display them in the output box, however I'm getting Non-static method 'setText(java.lang.CharSequence)' cannot be referenced from a static context, but I don't know what the static thing is  private void onClick(View v) {     EditText input1 = (EditText) findViewById(R.id.input1);     double calc1 =  Double.parseDouble(String.valueOf(input1));     EditText input2 = (EditText) findViewById(R.id.input2);     double calc2 = Double.parseDouble(String.valueOf(input2));     double total = calc1 + calc2;     String result = Double.toString(total);     EditText output1 = (EditText) findViewById(R.id.output);     EditText.setText(result); }   The line giving the error:  EditText.setText(result);   Sorry if I'm being extremely incompetent but I searched and I couldn't really understand how to fix it. Thanks.


I 've unmounted a disk /dev/vdc1 on my machine, after I format it into xfs file system, I didn't mount it again, either didn't add the adequate line to fstab file.  Now when i want to mount this partition, but I can't access to it: mount: can't find dev/vdc1 in /etc/fstab or /etc/mtab.  So how should I put in fstab file so the system recognizes it again ? the partition was mounted on /Data


How can I install Windows after I've installed Ubuntu?

I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go  for UEFI only!


Not able to catch an exception (Custom + Standard) from trigger

Please consider the below scenario:   I have an Application__c object. I have a trigger on that (for simplicity, coded directly in trigger) which does one thing if the record name is Error then throws exception.     trigger ApplicationTrigger on Application__c (before insert, after update){          if(trigger.new[0].Name == 'Error'){             Application__c application;             System.debug(application.Name);         } }    Now I am running below code:     Now notice the catch statement is not executing, means system was not able to catch the exception. It came as the Fatal Error.   This is kind of a big issue where if there is null pointer or any other exception in trigger and exception handling code will not be able to do anything. Not even logging since it never reaches to catch block.   Let me know if you guys ever faced such situation and if yes what you did to make sure that it is properly caught.


Get both name and type of a single passed argument?

I need to write a method that takes both the name and the type of a passed argument. For example, a call might look like this:  MyMethod( nameof(MyVar), MyVar.GetType() );   Is there any way to simplify this call so that I pass only one argument instead of two, but the method can still figure out both the name and type of that passed argument? The only way I know is by creating a macro and running the source through a pre-build external C# preprocessor. Then the call could look something like:  MyMethod( MyVar );   ...but I want to avoid using a preprocessor.


A concise definition of a frame of reference in Newtonian mechanics?

I've read  on frame of reference and also followed all of the references cited in the text (Salençon, Brillouin, Norton, etc) but I'm struggling to find any concise definition in all of that.   I would like a concise definition for a frame of reference in the context of Newtonian mechanics. This definition should not involve any additional qualifiers such as inertial and must be mature enough as to differentiate a frame of reference and a coordinate system. Is there one such definition?


What do you call the home in which you grew up and spent most of your childhood: father home, mother home or what?

Your native country is your / "fatherland",  the land of your ancestors is your  and your first language is your . What do you call the home in which you grew up and spent most of your childhood (any other mother/father-containing word or phrase such as father home, mother home, maternal home, paternal home, or ___)? I want to use it in sentences like these:   "When I was single and still living in my ___, I didn't eat meat food at all, but after getting married I stared to change my habit."  After their parents' death, they sold their house and went to another city and took all of the memories of that ___ with them."    PS: In my country we call it "fatherhome".


How to prove Gauss's law div(E) = rho/epsilon from Coulomb's law?

As we know from coulomb's law that: $$\vec{E} = \frac{q}{4\pi\epsilon R^2} \hat{R}$$  using the above equation, how can I verify that: $$\vec{\nabla}\cdot \vec{E}=\frac{q}{\epsilon}$$  I have tried to do it a home, but couldn't figure it out. Explicitly showing all steps would be very much appreciated.


Please hide questions with tags I chose to ignore and hide (on iOS app)

I tend to use the Stack Exchange app over the weekends to do a bit of general browsing.  One of the sites is Board & Card Games, on which I've set it up, on the website, to hide magic-the-gathering tagged questions.  These still show on the iPad, and given the nature of the site tend to drown out most other questions.  The app already highlights questions tagged with a user's favorite tags.  Could we also have the app hide questions tagged with tags the user has marked for being ignored?


Glitchy-looking transparent alpha channel PNG when imported as "Image as Plane" in Cycles

I'm following , and when I import the reference image I get a glitchy plane:    (the one on the right is the Image as Plane, while the one on the left is an Empty with an image)  I have made sure that the image, found online, was transparent, using Photoshop:    In trying to troubleshoot this, I have looked at , but it doesn't help me, as I can't reproduce the steps given in the answer.  Basically, I'm stuck looking for parameters for this object. There's nothing in the Object Data panel, I tweaked Viewport Alpha in the Material tab but still nothing...


Test class error: System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out

I could have sworn this was working 2 months ago and now it seems suddenly broken (there are some slight changes I have tried to make today - making the method calls @future in @testsetup, also adding startTest and stopTest into testSetup - to no avail) What could I do to try and fix? or even to debug it -> not able to track where and why it is erroring out (I understand about making callouts and ensuring DML after the callout and/or different transaction and/or @future). If I remove the steps in @testsetup it works but those steps are needed to setup the admin data needed. I am 100% sure it worked fine about 2 months ago and I was getting 92% coverage. It seems to work ok on the QA/UAT server as well - just not in my SB all of a sudden  SyncUserTest.cls      @IsTest     private class SyncUserTest {         @testSetup         static void setupData(){            test.startTest(); //trying everything to create a separate txn            createAdminData();            createUsers();            test.stopTest();              }          @future //doesn't need to be @future but trying everything here to create separate txn         static void createAdminData(){             List<Application_Properties__c> custSettings=new List<Application_Properties__c>();             custSettings.add(new Application_Properties__c(name='DS_API_Enable',value__c='true'));             ......             insert CustSettings; //these custom settings are needed to pass parameters to the callout         }              @future //this definitely needed to be @future to avoid mixed DML issue         static void createUsers(){             UserDataFactory userDataFactory = new UserDataFactory(User.SObjectType);                  List<User> users = new List<User>();             .....             insert users;         }      @IsTest     static void testClose() {         List<User> listUsers = [select id from User where Isactive = false'];         test.startTest();         test.setMock(HTTPCalloutMock.class,new MockHTTPResponseGenerator());         Id batchId1= callBatches('CLOSE');         Test.stopTest();         listUsers = [select id from User where Isactive = false'];         system.assertEquals(...);     }      private static Id callBatches(String theMethod) {         return Database.executeBatch(new SyncUser(theMethod));     }   SyncUser.cls  global class SyncUser implements Database.Stateful, Database.Batchable<sObject>, Database.AllowsCallouts,Schedulable{ global Database.QueryLocator start(Database.BatchableContext BC){         ...         initRequest()         ... } global void initRequest() {         HttpRequest req = new HttpRequest();         req.setMethod('POST');         String authendpoint = settingsMap.get('DS_API_AuthEndpoint');         req.setEndPoint(authendpoint);         req.setHeader('Content-type', 'application/x-www-form-urlencoded');         ....         req.setBody(requestBody);         try{             Http http = new Http();             System.debug(Limits.getDMLStatements());             HTTPResponse res = http.send(req);         }         catch (Exception e) {             loginError= 'Error occurred during initial token management process: \n'+e.getMessage();             System.debug(loginError);         }   Debug log:  13:06:29.913 (2053116965)|EXCEPTION_THROWN|[120]|System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out 13:06:29.913 (2053368109)|USER_DEBUG|[151]|DEBUG|Error occurred during initial token management process:  You have uncommitted work pending. Please commit or rollback before calling out  I don't believe I need to move initRequest() to a separate @future method as I am not doing any DML there at all. AFAIK, the only DML I am doing so far, until the point of the error is in the testsetup where I am creating custom settings and test users (I have removed all triggers from UAT). I Can't move the lines in-between startTest and stopTest in testClose() because I need to mock the callout.


QGIS live GPS tracking /recommended hardware (GPS USB stick)

Is there a list or any other recommendation of certain GPS hardware (esp. GPS USB sticks) working with QGIS? I have been off this topic for far over a decade, and i remember that in former days not all GPS devices worked well with QGIS.  Additional information: Preferred OS at this time is Windows 10.


I recently got to know that two particles are entangled and they share information instantly no matter how far they are kept from each other. It is also said that if one particle is kept at one side of the universe and the other particle be kept on the other side of the universe, then also the information sharing will be instant between the two entangled particles. But I am confused that does it violates the theory of special relativity which says that nothing can travel faster than light but in the case of quantum entanglement, the information is transferred instantly. Because I know that light will take billions of years to travel from one side of the universe to the other side(if seen from any other reference frame), but what if we take the reference frame itself of the light? Then the time, taken by the light to travel from one side of the universe to the other one would be zero, isn't it?  If I am wrong please correct me. I really want to know about this, not in a mathematical way but in a simple understandable way as I have not touched the syllabus of quantum entanglement yet but read about it somewhere. Please help me with this.  Thanks in advance.


Command to move all windows to one workspace?

I want the command to work with Unity in 14.04.


I am going through a book on Python which spends a decent time on module reloading, but does not explain well when it would be useful.   Hence, I am wondering, what are some real-life examples of when such technique becomes handy?  That is, I understand what reloading does. I am trying to understand how one would use it in real world.  Edit:  I am not suggesting that this technique is not useful. Instead, I am trying to learn more about its applications as it seems quite cool.  Also, I think people who marked this question as duplicate took no time to actually read the question and how it is different from the proposed duplicate.  I am not asking HOW TO reload a module in Python. I already know how to do that. I am asking WHY one would want to reload a module in Python in real life. There is a huge difference in nature of these questions.


I created a new VM, and was able to ping it using its IP address.  However, I can't ping it by name - even though it belongs to the same "WORKGROUP" as my other windows machines.  What makes this particularly strange is the result of the following command:  C:\>ping -a 192.168.0.20  Pinging WIN-AOHA8MSD3D0 [192.168.0.20] with 32 bytes of data: Reply from 192.168.0.20: bytes=32 time<1ms TTL=128 ...   So the machine name can be queried, as indicated above, but when I turn around with that name it fails:  C:\>ping WIN-AOHA8MSD3D0 Ping request could not find host WIN-AOHA8MSD3D0. Please check the name and try again.   In case it is relevant, the VM is in VMWare Workstation 7.1 using a bridged network adapter.  The guest OS is Windows 2008 R2 SP1.  The host is Windows 7 x64.  Originally the ping of the IP address had not worked either, but I had created an ICMP rule on the guest OS that allowed the echo request.  What is necessary to make the machine name "pingable?"


Rings $R/I \cong h(R)/h(I)\,$ for injective ring hom $h$

I still struggle with elementary knowledge about quotient rings.  For example, why can I just write down the second following isomorphism:  $$\frac{\mathbb{C}[x, y, z]}{(x^2 + y^2 - 1, y \pm iz)} \simeq \frac{\frac{\mathbb{C}[x, y, z]}{(y \pm iz)}}{\frac{(x^2 + y^2 - 1,y \pm iz)}{(y \pm iz)}} \simeq \frac{\mathbb{C}[x, y]}{(x^2 + y^2 - 1)} $$  I know the first isomorphism is right by the third isomorphism theorem. But why can I write down the second one?


How to save output from command (eg. diff) into a variable

I want to test if there is any output from the diff (test if files are same), if none echo "Passed $x" else echo "Failed $x". I came up with some intermidiate step (save the output from diff to a file then read from file)  diff "./helloworld$x.out" "./output/helloworld$x.out" > tmp.txt; output="`cat tmp.txt`";  if [ "$output" = "" ];   then     echo "Passed $x";   else     echo "Failed $x";   fi;   I'm sure the code can be improved? Main question is: is it possible to save the output from diff directly into a variable?