How can I generate a unique identifier that is apparently not progressive

I need to identify items with a string of characters that is not apparently progressive. What I mean is that if I generate successive identifiers, they should not look like:  1, 2, 3, 4... a, b, c, d... k4f, k5f, k6f...  Also, the string should be preferably short and human-readable, ideally something you could easily say on the phone. So, a GUID is not a good candidate; a 6-characters long string with only uppercase consonants and numbers fits. Finally, the identifier has to be generated and reasonably guaranteed to be unique. GUIDs would be perfect for this, as it is extremely improbable to generate twice the same GUID when working at a reasonable rate. Assume that a "reasonable rate" is about 500 per day. Progressive integers (even in hex form) would work great, but then they'd be evidently progressive. What algorithm can I choose? I'm open to solutions like using a progressive ID and mangling it so that it doesn't look like it's progressive.


I can never understand why some people always got something negative to say. or  I can never understand why some people always have something negative to say.


how to define good language for the theory of vector space?

what would be a good language for the theory of vector space?There are two different varieties of objects , scalars and vectors.


What is the name for this filming technique?

Serving as as a transitional technique, sound effects / visual effect from the upcoming movie scene will play before its scene is presented.   For example, in this video clip below, around 0:08, sink hole becomes a turning wheel.    Second example:   Two men are having a conversation in a room and when the camera still focuses in this room but sound effect of a steam train starting starts to play; a few seconds later, the camera switches to a train platform.


I was wondering if anyone could point me in the direction of some good sources to learn about user-defined styles in pgfplots? I've been through the pgfplots manual but it seems to only touch on this subject. So far I've been able to define some styles of my own, and call them without any issues, but I'd like to expand on this functionality, and for that I need some more detail about what styles are and aren't capable of, and what the appropriate syntax is. Some of my questions are:  Q1: Can I define nested styles? For example, my preamble defines MyStyle1 like so:  \pgfplotsset{MyStyle1/.style={code-goes-here}}   I then call this style in my document with something like this:  \begin{tikzpicture}     \begin{axis}[MyStyle1]           \addplot[MyStyleA] pseudo-code;     \end{axis}       \end{tikzpicture}   What I'd like to do is have MyStyleA have one definition if the axis uses MyStyle1, and a different definition if the axis is using MyStyle2. Can this be done? How would I go about this?  Q2: How do I overwrite parts of a style? Let's say MyStyle1 includes the line xmin=5, and I apply MyStyle1 to an axis environment as above. I want the minimum x value to instead be 0, but to otherwise use all other settings from MyStyle1. How do I override this for just this axis environment (i.e. not affect any other things that use MyStyle1)?  Q3: Are there any limitations to what I can put in a style? I'm assuming any settings I can put in [] brackets can also be put in a style. Any exceptions or additions to this rule?


How to calculate the distance between two cities in Java

I am trying to create a program to find the distance between two user inputted cities in java.  I've looked at a few other posts, and I've seen the Geocoder API recommended, to get the lat and lang values for the cities. However, I've only just started learning Java, and all those solutions were slightly complicated. Is there an easier method, or will I have to go about understanding API's?


I've this issue using Salesforce1 on mobiles (Android and IOS) with a long lightning component form: Tapping on an input text element at the bottom part of the form, scrolls the screen to the top. After the editing of the form element I'm not able to scroll again to the top and forcing it fires the overscroll, refresh the all page and losting all inserted data.  To reproduce: lightning component form  <aura:component implements="force:appHostable"> <ltng:require styles="/resource/SLDS0120/assets/styles/salesforce-lightning-design-system.min.css"/>
TEST PAGE START

         Input Label
             <input id="inputSampleSmall" class="slds-input slds-input--small" placeholder="placeholder" type="text"  />

TEST PAGE END

     1 - After tapped on the imput text field, the focus is in it but the screen scroll to the top when mobile keyboard is showed into the screen.  2 - Starting writing, force the screen back to the imput text field; You can see what you are writing.  3 - After wrote, mobile keyboard is hidden and you see screen in the correct position.  4 - If you try to scroll to the top you cant as the top limit is noe set to the actual screen position (much below the real top) and forcing the scroll fires the overscrolling and refresh the all page, losing all data set.  Have someone the same issue??  Thanks!


How one can evaluate following limit:  $$\lim_{x\to\infty} x\left(\frac{1}{e}-\left(\frac{x}{x+1}\right)^x\right)?$$  I've found this exercise in the chapter about Taylor series, but I have no idea how to solve it.


Plot graphs, shade areas and lines with Tikz

How could I do the following plot with Tikz:  I'm new on Latex (and Tikz), thanks for your help!


Represent Integer as sum of at least two consecutive postive Integers

For the case that a natural number $N =c\cdot k$ where $c$ is odd, we can easily represent $N$ as following sum  $$N = \sum_{n = k - \frac{c-1}{2}}^{k + \frac{c-1}{2}} n$$  This covers all integers except for powers of two: $N=2^l$. Some experimenting suggests that we cannot decompose powers of two as sum of consecutive positive integers, but is there a way to prove this, or is there a counter example?


Ever encountered this "http://mattker.hu/images/image.php" in scripts in your site?

My site was hacked. Most html and javascript files in my site were modified to included the link in the question title. What strategies should I employ to reduce the likelihood of my site being hacked again?


Could VS C++ compiler miss an instantiation of an abstract class

Would it be possible through funny initialization and/or casting to base classes to achieve an instance of an abstract class or class which has pure virtual methods?   I'm using the VS14 compiler and I'm wondering if the compiler could miss this? The class and its use are in separate assemblies.  To be clear I'm not trying to achieve this, just looking at bugs and wondering if this could lead to a runtime exception of calling a pure virtual method.


How to find out if my system is i386 or x86_64 before installing Ubuntu?

I am using Windows as of now and want to install Ubuntu. I want to find out if my system is i386 or x86_64? How do I do that?


Real time video stream AES encryption with authentication

I am now studying AES encryption for real-time video streaming. It seems that Netflix uses the AES-GCM (or CBC + MAC) mode for real-time video encryption and authentication. With MAC authentication, the client can only get the MAC message after the whole video is encrypted and authenticated. After that, the client can verify and play the video. However, if the client wants to play the video immediately (without receiving and decrypting the whole video), how can the client verify the MAC message?  I guess the video stream may be divided into many small slices. The server will encrypt and authenticate those slices one by one. At the receiving side, the client will verify, decrypt and play slice_1, then slice_2 ,then slice_3 and so on.  I am not sure whether my guess is right. Could someone please give me some advice? How does the real video provider's server do this kind of secure video stream transmission? If my guess is right, what is the typical size of video slices, or it is dynamic?


Refused UK visit visa TWICE but my circumstance is very different

I am an Indian citizen. My spouse and I applied for a UK visit visa on 29/11/2017 and re-applied on 14/12/2017 with tourism as the purpose. We were refused both times. I feel the ECOs are very inconsiderate and unfair.  I wish to bring to your notice that I earlier lived and worked in the United Kingdom from 2003 to 2007. Now kindly go through the concerns of the ECO in the following notices of refusal followed by my replies to their refusal.          After getting this refusal notice I stood up and gave them answers in my cover letter, with a new visa application, because I knew I was genuinely seeking entry and my intention was very clear in visiting the UK. Here is my cover letter which gave answers of their concerns/objections.          Now please can someone tell me where I went wrong or what else I should have done to satisfy the ECO? Every time they are coming up with new concerns. I am terribly disappointed and frustrated. Please help me out and explain what should have I done.  I can't post the second notice of refusal as it is not allowing me to post more than 8 links without having a reputation of 10 or more. I don't know, I am a new user. I can mail that if you like.  Do I have any merit to apply ever in the future? How do I change the circumstance other than my financial status? After all, I cannot go back in time and change what happened unknowingly and unwillingly.


Let's say I have 4 cameras on a scene:    I would like to render with the first camera, see what it looks like, then switch to the "next" camera quickly and see what that render looks like.  Currently, to switch cameras I have to click on a camera and set it as active and finally I can render (I don't have a number pad so I have to go to the menu and set it each time; else I'd use Ctrl+0). What I would like to know is whether there is a way to switch cameras and set it as active all in one step?  EDIT: I'm not asking how to set a camera as active, that's doable via menu, what I'm asking for is a guide for a "quick toggle" between cameras; a quick way to switch active cameras without an animation.


\hat{} not appearing in equation with transpose?

Why does the first bracket not display the \hat{\beta}, I cut and pasted from the second one so they are exactly the same? I guess it has to do with the fact that the first expression is transposed?      \documentclass{article} % Your input file must contain these two lines \usepackage{fancyvrb} \DefineVerbatimEnvironment{code}{Verbatim}{fontsize=\small}  \DefineVerbatimEnvironment{example}{Verbatim}{fontsize=\small} \usepackage{natbib} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{bm} \usepackage{grffile} \usepackage{graphicx} \usepackage{epstopdf} \usepackage{booktabs} \usepackage{siunitx} \usepackage{longtable}  \usepackage[%   font=small,   labelfont=bf,  figurewithin=section,   tablewithin=section,   tableposition=top  ]{caption} \numberwithin{equation}{section}  \makeatletter    \def\env@matrix{\hskip -\arraycolsep     \let\@ifnextchar\new@ifnextchar     \array{*\c@MaxMatrixCols l}} \makeatother  \begin{document} % plus the \end{document} command at the end \parskip = 1pc %change spacing between paragraphs \parindent = 0pc %change paragraph indentation \pagestyle{empty}  \clearpage \setcounter{page}{1} \pagestyle{plain}    \begin{equation}  SSR = (y-X \hat{\beta})^{T}(y-X \hat{\beta})     \end{equation}  \end{document}


Installation problem - missing boot manager

While trying to install from a USB stick, I get the message (from BIOS I think): "BOOTMGR is missing" and the computer hangs.  On my C drive is a corrupt version of Win 7 which I cannot repair or remove. Hence, having had enough of Microsoft, I would like to try Ubuntu.  Thanks in advance for your help.


The bronze review badges are fine, but the higher tiers do simply encourage grossly negligent reviewing too much. Not to say that reviewing shouldn't be appreciated, but having made the internet a better place should be incentive enough for anyone who honestly wants to review and not just grind through to a shiny badge.  To quote Nicol Bolas' :     As long as there's a shiny gold badge in it, someone will grind out reviews just to get it. Take away the incentive, and many people may stop reviewing altogether. Perhaps the latter might be a better option; at least then, you're getting people who actually care about reviewing involved.


So I've come to the understanding that a hadrons mass does not come from the constituent quarks but instead comes from a combination of things like binding energy and the mass energy of virtual gluons and quarks inside the hadron. But this doesn't make any sense from an energy stand point. If you have for example; 3 quarks that aren't bound together. And then you bind them together into a hadron, suddenly they gain mass. Wait a second! Doesn't this violate the conservation of energy? You could say that the mass is the result of the binding energy. But for a bound system, the binding energy must be negative. And so a bound system of quarks should be less massive than an unbound system. Why would quark ever want to bind together if the resulting system has much more energy? To summarize it all up, where does this mass come from?


I have a netbook MSI U135 DDR 2 1GB with Windows7 Starter. I want to install, alongside it, a Ubuntu version which is stable and fast running. Can anyone tell me which one to install?And to install Ubuntu alongside windows7 Starter, how to procede?  Greetz Chris.


When we have a series of episodes where every single episode depends on and develops from the previous, we may call that a sequel, or maybe a continuum.  Now let us say that we have a collection of fables, episodes or anecdotes that have the same characters, the same milieu, and the same themes; yet, this time, the episodes are NOT interdependent. They don't depend on each other in that you can watch/read 'any' one of them be it (in terms of order) from a beginning, medial, or final season, without having to watch/read the previous to understand, appreciate, and enjoy it (the one you're watching/reading). What do we call the 'episode' in this case?   Examples: a sitcom comedy show, or a show like Dr Who. Or, in literature, the novels of Sherlock Holmes.       Is there a specific term to describe the 'independent episodes' of these works?


Can a transnational marriage be performed over international waters?

Me and my fiancé are from two different countries. If we wouldn’t need a visa to get married over a cruise or in international waters, could we legally get married?


How to import a function from another directory file in python. Even have __init__.py file in that directory?

I have directory structures like below..     |---- folder1         |---- __init__.py         |---- python_file1.py    |---- folder2         |---- __init__.py         |---- python_file2.py   while i try to import like this "folder2.python_file2 import some_function".  it give an error: ImportError: cannot import name some_function  and also i had look many answer in stack overflow they said to insert file path if the directory without __init__.py file. But even i have __init__.py I cant able to import function from that directory. Let me clear about this error.  Thanks.


Combine Multiple ISO Files To Burn A Single Bootable ISO Image

I have three ISO files : "ubuntu-10.10-desktop-i386.iso", "ubuntu-11.10-desktop-amd64.iso, "ubuntu-13.04-desktop-i386.iso "  I want to combine those multiple ISO files and want to burn   a single ISO image file onto DVD that could let me use all of them. How can I do so.


Creating a covariance matrix with specified variances and correlations

I'm trying to generate a covariance matrix between two multivariate vectors with specified variances for each dimension, correlations between dimensions within a single vector, and cross-correlations between dimensions of the two vectors. When I try to generate multivariate normal data using this covariance matrix, I get a matrix not positive definite (PSD) error. Can someone please help me figure out why my matrix is not PSD? My Matlab code is below.  D = 2; % number of X variables P = 3; % number of Y variables N = 1000; % number of data points  %%% Choose variances of x's and y's stdX = gamrnd(1, 1, D, 1); stdY = gamrnd(1, 1, P, 1);  %%% Choose correlations between x's and y's corrX = corrcov(wishrnd(eye(D), D+1)); corrY = corrcov(wishrnd(eye(P), P+1)); corrXY = unifrnd(-1, 1, D*P);  %%% Construct covariance matrix for x's SigXX = nan(D); for i = 1:D     for j = 1:D         if i == j             SigXX(i,j) = stdX(i).^2;         else             SigXX(i,j) = corrX(i,j).*stdX(i)*stdX(j);         end     end end  %%% Construct covariance matrix for y's SigYY = nan(P); for i = 1:P     for j = 1:P         if i == j             SigYY(i,j) = stdY(i).^2;         else             SigYY(i,j) = corrY(i,j).*stdY(i)*stdY(j);         end     end end  %%% Construct cross-covariance matrix SigXY = nan(D, P); for i = 1:D     for j = 1:P         SigXY(i,j) = corrXY(i,j)*stdX(i)*stdY(j);     end end  %%% Construct full covariance matrix Sig = [SigXX SigXY; SigXY' SigYY];  %%% Generate fake data data = mvnrnd(zeros(D+P, 1), Sig, N);


Not sure how to do this. I had a hint to prove that $(2^x- 1)$ and $x$ have the same sign, but how would that help me? Please help!


I was wondering the following: Let's suppose that $G$ is a non-empty set, then, can we always find a binary operation $*$ such that $(G,*)$ is a group?  For example, if we fix $G=\mathbb{Q}$ the sum of rationals $+$ tell us that $(\mathbb{Q},+)$ is a group.  Another way to understand it: Is there a set for which we cannot find a binary operation such that is not a group?


One of the applications I use at work sometimes screws with my bash and so I don't see my own input anymore. I.e.  $ echo foo foo $   becomes  $ foo $   I incorrectly tried to run stty -echo which made matters worse and now it stopps accepting commands all together  which put my input in some state that just causes > to appear every time I line break and nothing else.  What should I have done?


Word for feeling conflicting emotions simultaneously

I've been trying to think of an adjective that expresses having two (or perhaps more) conflicting emotions or opinions simultaneously. Can anyone think of one?


I have installed a shutdown script on an Ubuntu system which doesn't get executed. It is an Amazon EC2 instance. I'm not sure it has to do with this fact just wanted to point it out.  The script should push some log files to an Amazon S3 bucket so it has to be executed while networking is up.  Here is how I installed the script:  1) Created the file in /etc/init.d/push-apache-logs-to-s3.sh with the required commands.  2) Made it executable with sudo chmod +x push-apache-logs-to-s3.sh  3) Executed sudo update-rc.d push-apache-logs-to-s3.sh start 0 0 .  Output from the above was:  update-rc.d: warning: /etc/init.d/push-apache-logs-to-s3.sh missing LSB information update-rc.d: see <http://wiki.debian.org/LSBInitScripts>  Adding system startup for /etc/init.d/push-apache-logs-to-s3.sh ...    /etc/rc0.d/S00push-apache-logs-to-s3.sh -> ../init.d/push-apache-logs-to-s3.sh   The contents of /etc/rc0.d/ is now:  lrwxrwxrwx  1 root root   17 Jul 31  2012 K09apache2 -> ../init.d/apache2 lrwxrwxrwx  1 root root   29 Jun 16  2012 K10unattended-upgrades -> ../init.d/unattended-upgrades lrwxrwxrwx  1 root root   26 Jun 16  2012 K15landscape-client -> ../init.d/landscape-client lrwxrwxrwx  1 root root   19 Apr 10 11:11 K20memcached -> ../init.d/memcached -rw-r--r--  1 root root  353 Jul 26  2012 README lrwxrwxrwx  1 root root   35 Jul 10 12:01 S00push-apache-logs-to-s3.sh -> ../init.d/push-apache-logs-to-s3.sh lrwxrwxrwx  1 root root   18 Jun 16  2012 S20sendsigs -> ../init.d/sendsigs lrwxrwxrwx  1 root root   17 Jun 16  2012 S30urandom -> ../init.d/urandom lrwxrwxrwx  1 root root   22 Jun 16  2012 S31umountnfs.sh -> ../init.d/umountnfs.sh lrwxrwxrwx  1 root root   20 Jun 16  2012 S35networking -> ../init.d/networking lrwxrwxrwx  1 root root   18 Jun 16  2012 S40umountfs -> ../init.d/umountfs lrwxrwxrwx  1 root root   20 Jun 16  2012 S60umountroot -> ../init.d/umountroot lrwxrwxrwx  1 root root   14 Jun 16  2012 S90halt -> ../init.d/halt   When I manually execute the script with sudo ./push-apache-logs-to-s3.sh, it does the intended job.  Are these scripts executed by root? What am I missing?


What is the purpose of using !! for Pointers in C Conditions?

I have seen code which uses a double not (!!)  for checking a pointer.But I am not finding an advantage of using !! in the condition check.Can some one shed some light on the purpose and advantage of using it.  int *Ptr; /* ... */ if(!!Ptr) {   /* ... */ }


Is 6/2 Romex the correct wire gauge for a 100' run to a workshop?

I bought an old house that has a fuse box. The place has a milk barn that I want to convert to a workshop. Can I run 6/2 wire from the the two 120 volts wires coming from the fuse box?    I want to run it into a 200amp breaker box in the barn. I will be using a 220V dryer and maybe a welder if that is possible.


Inshort Surface tension occurs due to imbalance of the intermolecular forces of attraction on water molecules. At the surface it is more so net force is inwards.  I read somewhere on this app that "which liquid has zero surface tension". But is it possible to have zero surface tension, because surface tension occurs if there is surface but if surface tension is zero it means there is no surface. Which doesn't make sense.


Diffeomorphism between the Grassmannian manifolds $\mathbf{Gr}(n,k)$ and $\mathbf{Gr}(n,n-k)$.

This seems to be a common exercise question, however I am having trouble with it. The hint is to use a map that associates the k-plane to its orthogonal complement. But I have not been able to show this as a diffeomorphism.   I was thinking of using the orthonormal basis and extending it to get a basis of $\mathbb{R}^n$, then using the remaining $n-k$ vectors to generate the orthogonal complement. Am I on the right path??How else should I approach this otherwise??


How should i phrase this?  She wished it was as easy as he thought.  or   She wished it were as easy as he thought.


What can cause "Discovered - currently not indexed" in the new GWT

The new GWT shows sitemaps links divided into new categories. Two that confuse me:  1. Discovered- currently not indexed 2. Crawled - currently not indexed  What are the possible reasons for this, and are there any site wide implications? Is this a sign from Google I should consider removing these?


14.10 Trackpad works correctly on live CD, but not after installation

I purchased a Dell Inspiron 7746 notebook, and have installed Ubuntu 14.10 on alongside Windows.   All has worked well so far, but I am having a frustrating getting the trackpad to work correctly. The trackpad worked great when running from the Live CD, but once I actually installed the OS, I found that it's operation to be undesirable.  Here are the issues I am having:   Tap to click does not work. Clicks are only registered when pressing the clickpad Two-finger tap to right-click does not work. In fact, right-clicking is not possible at all. Pressing the clickpad in the right-click area does not register as a right-click. Two finger scrolling does work, however, after scrolling, any single finger trackpad action is also registered as a scroll. The only way to fix this is to two-finger scroll again. Trackpad does not disable while typing.   Here are some of the workarounds I have tried after doing some googling:   Ran synclient tapbutton 1=1  Added Option "TapButton1" "1" to 50-synaptics.conf Did a fresh install of 14.10 (several times, actually)   Perhaps the most frustrating thing about this is that the trackpad works beautifully on the live CD, just not when the OS is installed. Using a wireless USB mouse now, but would love to get this issue resolved. Thanks!


How do I write a Unity system indicator in Python?

Background:   This is NOT for application-indicators but system-indicators.     Picture from:  The objective is to show  in Greeter/Lock/Ubiquity screens. There is a work around in:     C Original Code: (working fine)   I already get one working in C language, see my other question:    However, indicator-sysmonitor is already developed in Python as many other application indicators. I don't like the idea that developers obliged to port their projects to C or write a Python-C proxy if they want to show the indicator in greeter/lock/ubiquity screens. Instead, making indicator-sysmonitor creates a system indicator directly from python would be the best solution (no workarounds, and it will be a generic solution for all python projects that currently using appindicator).   Python Code: (My failed trial to port c code to python)   I'm struggling to port it into Python. Here is my current code which doesn't work. It does create DBus object for both Menu & Actions. It is listed in the XFCE indicators plugin. But not showed on the panel.  /usr/lib/indicator-test/indicator-test-service  #!/usr/bin/python2  import os import sys  import gi from gi.repository import Gio, GLib  APPLICATION_ID = 'local.sneetsher.indicator.test' DBUS_MENU_PATH = '/local/sneetsher/indicator/test/desktop' DBUS_ACTION_PATH = '/local/sneetsher/indicator/test'  def callback():     print ok  def quit_callback(notification, loop):     global connection     global exported_action_group_id     global exported_menu_model_id      connection.unexport_action_group (exported_action_group_id)     connection.unexport_menu_model (exported_menu_model_id)      loop.quit()  def cancel (notification, action, data):     if action == "cancel":         print "Cancel"     else:         print "That should not have happened (cancel)!"  def bus_acquired(bus, name):     # menu     submenu = Gio.Menu()     submenu.append("Show", "show")     item = Gio.MenuItem.new(None, "_header")     item.set_attribute([("x-canonical-type","s","com.canonical.indicator.root")])     item.set_submenu(submenu)     menu = Gio.Menu()     menu.append_item (item)      actions = Gio.SimpleActionGroup.new()     action1 = Gio.SimpleAction.new("_header", None)     actions.insert(action1)     action2 = Gio.SimpleAction.new('show', None)     actions.insert(action2)     action2.connect("activate",callback)      global connection     connection = bus      global exported_action_group_id     exported_action_group_id = connection.export_action_group(DBUS_ACTION_PATH, actions)      global exported_menu_model_id     exported_menu_model_id = connection.export_menu_model(DBUS_MENU_PATH, menu)  def setup ():     #bus connection     Gio.bus_own_name(Gio.BusType.SESSION, APPLICATION_ID, 0, bus_acquired, None, None)  if __name__ == '__main__':      connection = None     exported_menu_model_id = 0     exported_action_group_id = 0     password = ""      loop = GLib.MainLoop()     setup ()      loop.run()   local.sneetsher.indicator.test  [Indicator Service] Name=indicator-test ObjectPath=/local/sneetsher/indicator/test  [desktop] ObjectPath=/local/sneetsher/indicator/test/desktop  [desktop_greeter] ObjectPath=/local/sneetsher/indicator/test/desktop  [desktop_lockscreen] ObjectPath=/local/sneetsher/indicator/test/desktop   local.sneetsher.indicator.test.service  [D-BUS Service] Name=local.sneetsher.indicator.test Exec=/usr/lib/indicator-test/indicator-test-service   90_unity-greeter.gschema.override  [com.canonical.unity-greeter] indicators=['ug-accessibility', 'com.canonical.indicator.keyboard', 'com.canonical.indicator.session', 'com.canonical.indicator.datetime', 'com.canonical.indicator.power', 'com.canonical.indicator.sound', 'local.sneetsher.indicator.test', 'application']    Question:  I expect the reason why, I didn't create the menu structure or its meta (pseudo items like _header) as they are in the original C code.  Could anyone make a working port of  to Python?


When referring to study at Oxford why is the word "read" used?

When reading about people who have studied at Oxford the word "read" is used instead of study. Example:  "He read Philosophy, Politics and Economics at Oxford"  Why when discussing study at Oxford (and maybe other universities) is the word "read" used?


Why elements in array of the objects are not updating?

while creating an application using JavaFX i faced a little problem - elements in my array are somehow not updating with changes which are made on these elements. On the start I want to point - dont pay attention on structure and model of my app - I already know It is not good and I changed it but i still dont understand why my problem existed. This how initialization of my array look like:  public class GameBoardAI implements IGameModel{   Random rand = new Random(); int currentPlayer = 1; TicTacViewController tacController = new  TicTacViewController(); Button[] buttonss = new Button[]{ tacController.btn1, tacController.btn2, tacController.btn3, tacController.btn4,          tacController.btn5, tacController.btn6, tacController.btn7, tacController.btn8, tacController.btn9};     The problem is, that when I am creating the array of buttons, buttons are not connected to the view yet, so they are still nulls. And when I am trying to invoke some methods on my buttons inside I encounter a problem:  public void switchPlayer() { if(currentPlayer == 1) {                   currentPlayer=2;     buttonss[rand.nextInt(9)].fire();  } if(currentPlayer == 2)     currentPlayer = 1;   }  You can see here, that I am trying to get some random button, from array of buttons i created in instance variable. Here is the part of code, when buttons are located inside TicTacViewController:       public class TicTacViewController implements Initializable {  @FXML private Label lblPlayer;  @FXML private Button btnNewGame;  @FXML private GridPane gridPane;  private static final String TXT_PLAYER = "Player: "; private IGameModel game = new GameBoard(); @FXML public Button btn1; @FXML public Button btn2; @FXML public Button btn3; @FXML public Button btn4; @FXML public Button btn5; @FXML public Button btn6; @FXML public Button btn7; @FXML public Button btn8; @FXML public Button btn9;   As i understood, the problem is, that when I am creating the array as instance variable, mu buttons are still null - they are not connected to the view yet. But here happens some strange thing: When I am putting array initialization inside a switchPlayer method instead of doing this as instance variable - everything is working correctly. So it seems like when I am creating array while invoking a method buttons are already connected to the view and there is no problems. And it ruins my knowledge about reference variables - why it is not working when we are creating array as instance variable?  Because i thought that even if we have a reference variables inside a array - when we will change this reference variables, they will be also changed in our array. To be more specific - even if when we are initalizing an array and buttons are not connected to the view yet, they are connecting afterwards - so when we are invoking a switchPlayer method butttons should be already connected to the view - but compiler is telling me that they are null. Can someone explain me what is the problem here? Why while invoking a method buttons are still null, as they were in array creation even if they were connected to the view afterwards?


i've commented an answer on SO, but now i could not find the Question/Answer again. Is there a way, to see all my comments for finding the SO-Page?  Thank you


Do creatures put on the battlefield via a sorcery have summoning sickness?

I have a card named , the effect of this card is "For each creature you control, Search your library for a creature with the same name and put it onto the battlefield. Then Shuffle your library".  After this phase can I then attack with the creatures gained this way or do they suffer from summoning sickness?  My guess is that If they do not have haste they suffer but doubling them seems to suggest a mirroring of the original creature at the time... Its a vague mechanic in all honesty


I need a USB cable for the above device so I can connect it to my pc and upload the pictures. does anyone know what USB cable I need? box states USB 2.0 which isn't much use to me.


PES 2012 results in a Nvidia error on Dell N5110 regarding System Requirements?

I bought a Dell N5110 laptop and installed . The Nvidia graphics card in the laptop has 1 GB of RAM, but when I try to run the game, a message appears that says there is only 128 MB of graphics memory.   Here is the message:     Warning : Your computer does not meet the Minimum System Requirements to run this software. As a result, you may experience errors during operation. Your Video Card does not meet the required specifications. (GPU:VRAM 128MB)   What could the problem be?


In PHP 7, what is the difference between using self and $this? When is each appropriate?


Force user to write excerpt before saving post?

Is it possible, in functions.php, to force users by default to write an excerpt before they can save a post?  And ideally, would it be possible to make this mandatory in only certain post categories?


NullPointerException when overridding onSelectionChanged in custom edittext

Any variables that are referenced in onSelectionChanged are null according to the debugger, and if I run my sample app with the following added to a simple layout my app crashes with a nullpointer.  <com.dummy.DummyEditText                 android:layout_width="wrap_content"                 android:layout_height="wrap_content"/>  The simplest example of a custom AppCompatEditText package com.dummy  import android.content.Context import android.util.AttributeSet import androidx.appcompat.widget.AppCompatEditText  class DummyEditText : AppCompatEditText {      constructor(context: Context) : super(context)     constructor(context: Context, attributeSet: AttributeSet) : super(context, attributeSet)     constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int) : super(context, attrs, defStyleAttr)      private val a = String()     override fun onSelectionChanged(selStart: Int, selEnd: Int) {         a.toString()     } }  with the stacktrace      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference         at com.dummy.DummyEditText.onSelectionChanged(DummyEditText.kt:15) 2020-10-05 12:14:25.794 22859-22859/com.dummy E/AndroidRuntime:     at android.widget.TextView.spanChange(TextView.java:10744)         at android.widget.TextView$ChangeWatcher.onSpanAdded(TextView.java:13600)         at android.text.SpannableStringBuilder.sendSpanAdded(SpannableStringBuilder.java:1287)         at android.text.SpannableStringBuilder.setSpan(SpannableStringBuilder.java:777)         at android.text.SpannableStringBuilder.setSpan(SpannableStringBuilder.java:676)         at android.text.Selection.setSelection(Selection.java:96)         at android.text.Selection.setSelection(Selection.java:78)         at android.text.Selection.setSelection(Selection.java:153)         at android.text.method.ArrowKeyMovementMethod.initialize(ArrowKeyMovementMethod.java:312)         at android.widget.TextView.setText(TextView.java:6299)         at android.widget.TextView.setText(TextView.java:6139)         at android.widget.EditText.setText(EditText.java:121)         at android.widget.TextView.<init>(TextView.java:1642)         at android.widget.EditText.<init>(EditText.java:87)         at android.widget.EditText.<init>(EditText.java:83)         at androidx.appcompat.widget.AppCompatEditText.<init>(AppCompatEditText.java:74)         at androidx.appcompat.widget.AppCompatEditText.<init>(AppCompatEditText.java:69)         at com.dummy.DummyEditText.<init>(DummyEditText.kt:10)  So the question is why is the variable a null? It should have been instantiated when it is first referenced in the onSelectionChanged regardless of how DummyEditText is instantiated. What am I missing here? Any pointers on what is going on are appreciated!


windows 7 home premium reinstallation problems

My dell Studio 1749 is over 6 years old and has never given any problems.I need to reinstall windows becasue a few weeks ago after doing updates from windows it started telling me my copy of windows build 7601 was not genuine.So I took the machine in to be cleaned etc and using my oem installation disks (64bit) reinstalling windows.  Unfortunately the oem disks have become corrupted but I have the product key etc. Dell do not seem to be interested.  I live in Turkey and a friend downloaded another windows 7 on my computer but 32bit.  The video drivers seem to need updating and everything is slower than before.   As you can see I am useless at this sort of thing and because of my location there is the added language problem.  Can anyone come up with any ideas of how I can get my lovely machine back?


Given a rectangle (4 vertices), how to make ONLY ONE of the corner rounded

You can apply Subdivision Surface modifier to round all corners but it will result in all corners being rounded.    How do I make it such that only ONE corner is rounded?  Is it possible?


Is it possible to get a free 15 day visa upon arrival at Hanoi airport?

I read somewhere its possible to get a free 15 day Vietnam visa upon arrival at Hanoi airport as long as I show proof I'm leaving Vietnam within 15 days, which I am. I'm flying to Hanoi from Kuala Lumpur, will I have a problem boarding my flight with no Vietnam visa or visa approval letter?  I have 2 passports, Malta and Australia.


Moving MXD to different folder without breaking links using ArcPy?

I was wondering what was the equivalent of "Save As" in ArcPy, which works perfectly fine in ArcMap. As the MXDs are currently set up with relative path moving MXD would break the links, however if MXD is saved with "Save As" option the links would be fine. I was trying to automate the procedure as there are too many files. SaveACopy (option 1) is breaking all links which is given below:  Option 1  import arcpy, os  srcdir = r"C:\temp\test1"  for basename in os.listdir(srcdir):     if basename.endswith('.mxd'):         mxdPathName = os.path.join(srcdir, basename)         mxd = arcpy.mapping.MapDocument(mxdPathName)         mxd.saveACopy(r"C:\temp\test1\test2\\" + basename)   I have tried to set the MXD to absolute path (option 2) and copy as a new copy which isn't working either (links are still broken).  Option 2  import arcpy, os  Workspace = r"C:\temp\test1" arcpy.env.workspace = Workspace  mxdList = arcpy.ListFiles("*.mxd")  for file in mxdList:     filePath = os.path.join(Workspace, file)     filePathCopy = Workspace + r"test2\\" + file     mxd = arcpy.mapping.MapDocument(filePath)     mxd.relativePaths = False     mxd.save()     mxd.saveACopy(filePathCopy)     mxdCopy = arcpy.mapping.MapDocument(filePathCopy)     mxdCopy.save()     mxdCopy.relativePaths = True     mxdCopy.save()     mxd.relativePaths = True     mxd.save()


Java Swing NULL Exception when calling updateComponentTreeUI();

Making the following call:  SwingUtilities.updateComponentTreeUI(comp);   which sporadically results in the following error :  Exception in thread "AWT-EventQueue-0"  java.lang.NullPointerException     at javax.swing.plaf.synth.SynthArrowButton$SynthArrowButtonUI.getPreferredSize(SynthArrowButton.java:106)     at javax.swing.JComponent.getPreferredSize(JComponent.java:1662)     at javax.swing.plaf.basic.BasicScrollBarUI.layoutVScrollbar(BasicScrollBarUI.java:666)     at javax.swing.plaf.basic.BasicScrollBarUI.layoutContainer(BasicScrollBarUI.java:866)     at java.awt.Container.layout(Container.java:1511)     at java.awt.Container.doLayout(Container.java:1500)     at java.awt.Container.validateTree(Container.java:1696)     at java.awt.Container.validateTree(Container.java:1705)     at java.awt.Container.validateTree(Container.java:1705)     at java.awt.Container.validateTree(Container.java:1705)     at java.awt.Container.validate(Container.java:1631)     at javax.swing.RepaintManager$3.run(RepaintManager.java:711)     at javax.swing.RepaintManager$3.run(RepaintManager.java:709)     at java.security.AccessController.doPrivileged(Native Method)     at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)     at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:708)     at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1731)     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)     at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)     at java.awt.EventQueue.access$500(EventQueue.java:97)     at java.awt.EventQueue$3.run(EventQueue.java:709)     at java.awt.EventQueue$3.run(EventQueue.java:703)     at java.security.AccessController.doPrivileged(Native Method)     at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)     at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)     at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)     at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)     at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)   Apparently some component is becoming null. Added the following IF condition but it doesn't help :  if (comp != null)       SwingUtilities.updateComponentTreeUI(comp);   Going through the stack and it is purely a java stack and no reference to custom code. There are actually other NULL exception similar but referencing other Java objects.   Is there a way to iterate through the components in this tree to find which component is returning a null?


How long is too long to condition a beer in secondary without having to pitch bottling yeast? What factors do I need to consider when deciding whether or not to pitch yeast at bottling?


Appropiate way to safely transportate heavy laptop during flight?

I flew a long range flight carrying my laptop, a quite heavy one, inside a neoprene briefcase on the passenger cabin. The recommendation by the aircrew is to place them in the compartments above or below the front seat. However, during take-off and landing, the vibrations on the plane are quite strong and, as a result, it received minor damages.   Placing them in the above compartments might be equivalent as placing it in the floor, underneath the front seat, with the added hindrance of additional luggage.  I considered the alternative of holding it vertical by the handle while sitting, so it won't be any contact with the aircraft's floor. This is impracticable during cruise, but I thought it could be better during the take-off and landing segments.  Other option I considered is to wrap it with completely with bubble wrap before boarding the plane.   The damage the laptop sustained was not great, but I am afraid of further damage as the date of my return flight approaches.  The question is:     Which is the safest way to transport a laptop during flight?    I don't think it's an inappropiate question, as the requirements are clearly defined and surely must be an optimal way to transport heavy tech while travelling. Even if, for some reason, it's deemed unsuitable or off-topic, I truly believe that it's an important subject, and I would be most pleased to receive your input.


How do I completely disable password ssh logins?

I'm setting up a raspberry pi 3 running the raspbian operating system, that will be connected to wifi constantly with ssh enabled, thus security is a must.  I have successfully enabled login via a public-private key pair, and am trying to make this the ONLY way to access the pi via ssh.    I've looked at a few threads on this topic, and scoured my sshd_config file for anything that smacks of a password login (PasswordAuthentication, PermitRootLogin, KerberosAuthentication, UsePAM, etc.) to turn them all off, but to no avail.  As soon as a login with the public key fails, it immediately prompts for the password.    I've restarted sshd and even rebooted the pi several times, but nothing changes.    I'm not too desperate since the password is quite strong, but it seems like such a waste to use a public key login if password logins are possible.


combine both javascript events together not working

Having trouble to combine both javascript events together Both class actions occurred in different clicks.   <script>     //first event     $("#add-product-details-video").click(function () {         hideAlertMsg();     });     //second event     $(".add-more-image").on('click', function () {         hideAlertMsg();     }); </script>


Why is the derived class constructor is skipped?

I have a code like this  class Base { public:     Base() {}; };  class Derived : public Base { public:     Derived() {cout << "Derived" << endl;} };  int main() {     Derived a(); // Only called base constructor     Derived b;   // called derived constructor }   What is the difference between these two calls? My understanding is that base constructor is always called before derived constructor? Why is the derived constructor skipped?  Thanks,


How to do the same crop on a batch of photos?

I've got a batch of photos (an owl coughing up a pellet in case you're curious).  I want to make an animated GIF out of them, but the result would be improved if they were all given an identical crop first.  I'm currently using Picasa for my basic photo editing on a Windows 7 PC.  While Picasa does have batch editing, crop is not one of the items on the batch menu.  Does Lightroom have a batch crop?  If there's a way to get Picasa to show me the coordinates of the crop selection rectangle, I could also use that information to do the same crop repeatedly.  Are there any tools that let you crop an animated GIF?  I know I can create the animated GIF by uploading the component images to Google+ and then looking in the Auto Awesome area. I don't know about tools for working with animated GIFs.


How can I create a bibliography like a section?

I have the following:   \documentclass{article}  \usepackage{multicol}   \begin{document}  \begin{multicols}{2}   \section{}  \begin{thebibliography}{99}   \subsection{Differentiation}   \bibitem{DifIntWiki}    \emph{URL}   \end{thebibliography}  \end{multicols}  \end{document}   It creates a section with a number, and the Bibliography follows on the next line.  I'm interested in combining these two lines together, essentially turning the bibliography into a section.  Is there any way to do this?  Additionally, I'm using the multicol package, so I'm wondering if there is a way to do this without affecting the columns.


Do internal forces cause change in velocity?

For the earth sun system, the force of gravitation is an internal force ( forces* a newtons third law pair)  and this INTERNAL force  is causing the earth to accelerate. . it is providing the necessary centripetal force.   Reasoning behind the question:  centripetal forces dont do any work and hence dont cause a change in mechanical energy, dont cause a change in kinetic energy therefore and dont cause a change in velocity.   QUESTION question 1) but the earth is undergoing a change in velocity?  so, is the the gravitational force on the earth an external force? but ive considered our system containing the sun too. shouldn't that be an internal force then?  2) in the earth sun system if for simplicity we call the earth's movement uniform circular motion, is momentum conserved in this system? how?  i suppose ive mixed up too many things


Cannot get packages from official repository for eoan

Today i noticed the very strange thing. Running sudo apt update tells me such terrible words: $ sudo apt update Ign:1 http://archive.ubuntu.com/ubuntu eoan InRelease Ign:2 http://archive.ubuntu.com/ubuntu eoan-updates InRelease                   Err:3 http://archive.ubuntu.com/ubuntu eoan Release                               404  Not Found [IP: 91.189.88.152 80]  Ign:4 http://security.ubuntu.com/ubuntu eoan-security InRelease                 Err:5 http://archive.ubuntu.com/ubuntu eoan-updates Release                       404  Not Found [IP: 91.189.88.152 80] Err:6 http://security.ubuntu.com/ubuntu eoan-security Release   404  Not Found [IP: 91.189.91.39 80] Reading package lists... Done          E: The repository «http://archive.ubuntu.com/ubuntu eoan Release» does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details E: The repository «http://archive.ubuntu.com/ubuntu eoan-updates Release» does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details E: The repository «http://security.ubuntu.com/ubuntu eoan-security Release» does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details  Does it mean that official repository for Ubuntu eoan aren't supported more?


Link broken on desktop but work on nautilus file manger

I created a shortcut to a text file called "imp" on right-clicking it from the default file manager everything works well. But on clicking it on the desktop I get this  Any Idea why?


PHP simplexml: why does xpath stop working?

A strange thing happened after a supplier changed the XML header a bit. I used to be able to read stuff using xpath, but now I can't even get a reply with  $xml->xpath('/');   They changed it from this...  <?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE NewsML SYSTEM "http://www.newsml.org/dl.php?fn=NewsML/1.2/specification/NewsML_1.2.dtd" [ <!ENTITY % nitf SYSTEM "http://www.nitf.org/IPTC/NITF/3.4/specification/dtd/nitf-3-4.dtd"> %nitf; ]> <NewsML> ...   to this:  <?xml version="1.0" encoding="iso-8859-1"?> <NewsML   xmlns="http://iptc.org/std/NewsML/2003-10-10/"   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   xsi:schemaLocation="http://iptc.org/std/NewsML/2003-10-10/ http://www.iptc.org/std/NewsML/1.2/specification/NewsML_1.2.xsd http://iptc.org/std/NITF/2006-10-18/   http://contentdienst.pressetext.com/misc/nitf-3-4.xsd" > ...


I have installed Ubuntu and chose option 'something else' and i created partitions, but now i cant boot to windows but when i re-install Ubuntu there is an option to install it along with windows  7. I want to completely remove Ubuntu 13.04 but i cant i need windows 7 for school work i tried BIOS, Image discs ISO file, but still only thing i can do is to install UBuntu 13.04 but not version 12, 11 nor 10.


Mail app Keeps opening, can't find notification options on google calendar

I know, there are a lot of peoples asking this, and I followed every single guide, but I REALLY DO NOT found the "calendars link" and so I can't keep following the guide...Has google changed the layout or something else, I don't know. But I really need to fix this mail problem, even apple support has said to me "There is no solution for this problem at the moment, keep your macbook up to date". Really thanks to those that can help me.


I'd like to know if there are books about how to design electronic circuits.  I have lots of theoretical books that cover how to analyse circuits, but I'd like to read about something more practical, like how to actually design something and what to look out for.  So for example, in my circuit theory books, say like Sedra And Smith, they analyse, say, Cascode amplifiers and come up with large convoluted expressions for things like gain and input and output resistance; it seems like it's impossible to really use those equations to design anything (though they are helpful in understand the circuit).  I guess I'd basically like a book that goes through the design of standard building block circuits, like differential amplifiers with current sources and active mirrors and multistage amplifiers etc.  Could anyone point me in the right direction?


I have script with #!/bin/ksh in the first line. When I try to execute this script (run ./myscript.sh) the error occurred:  -bash: ./myscript.sh: /bin/ksh: bad interpreter: No such file or directory   But when I execute this script through source myscript.sh or bash myscript.sh command - script runs successfully.  Yes, ksh is not installed and it is correct to install this. But I can't understand different behavior ./ and bash or source


change caption in tufte class full-page figure

I've tried to change the caption in a full-width float with tufte-book, but to no avail. I want the caption in this figure to be like more common LaTeX classes.  Here is a MWE and the result:  \documentclass[a4paper,nohyper]{tufte-book} %abstracton \usepackage{fontspec} \defaultfontfeatures{Ligatures={TeX}} \setmainfont[Numbers={OldStyle}]{Minion Pro} %or any other font \setsansfont{Myriad Pro} % or any other font \setmonofont[Scale=MatchLowercase]{Menlo} \usepackage{graphicx} \usepackage{wrapfig} \usepackage{sidecap} \usepackage[dvipsnames]{xcolor} \usepackage{polyglossia} \setmainlanguage{brazil} \usepackage[bookmarks]{hyperref} %\usepackage[font=sf, labelfont={sf}, margin=1cm]{caption} \newfontfamily{\A}{Al Bayan}  \begin{document}  \begin{figure*} \centering \includegraphics[width=.9\textwidth]{./camp-scene} \caption{Cena de Acampamento. Mir Sayyid Ali, séc. XVII. 28,4 x 20 cm. Harvard University Art Museums, 1958.75. Os tecidos preenchiam a vida tanto dos nômades quanto dos habitantes das cidades, cobrindo o chão e definindo o espaço. O papel onipresente dos tecidos é visto numa pintura de um acampamento nômade, atribuído ao pintor persa do século XVI Mir Sayyid Ali.} \label{fig:camp-scene} \end{figure*}  \end{document}


I am forcing my webserver to rewrite a none www URL to www, e.g. https://example.com to https://www.example.com, via .htaccess.   RewriteCond %{HTTP_HOST} !^$ RewriteCond %{HTTP_HOST} !^www\. [NC] RewriteCond %{HTTPS}s ^on(s)| RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]   But my site does not load with www and prints ERR_TOO_MANY_REDIRECTS.  If I enter a URL like https://www.example.com/some-uri then I get redirected to https://example.com  DNS Zone Records   What might be the cause?


I would like to know how many of my friends follow me on Facebook. I have looked up my profile on other peoples Facebook accounts and try to log on to my account through a computer for room and yet I still am unable to find out how many followers I have.


I'm newbie and I don't know how Drupal 7 work! I want to remove with and height from below code:  <img typeof="foaf:Image" src="http://ashkanplastic.loc/sites/default/files/styles/large/public/slider-1a_0.jpg?itok=k4X3QU5U" width="480" height="236" alt="">   Could you please introduce to me why I can not find 480 with $ grep -H -R 492? And please help to remove width and height.


Textbook on the *theory* of neural nets/ML algorithms?

Every textbook I've seen so far describes ML algorithms and how to implement them.  Is there also a textbook that builds theorems and proofs for the behaviour of those algorithms? e.g. stating that under conditions $x,y,z$, gradient descent will always lead to $A,B,C$?


Throughout Game of Thrones, we have seen multiple  die. As far as I remember:   Sam killed one with dragonglass. Jon Snow killed one with Longclaw. Meera Reed killed one with a spearhead made of dragonglass.   So are there a set number of White Walkers that were created by the ? If so, about how many are there?  OR  Can the  just create as many as he wants?


On the bash prompt one, three or more slashes (/,///,////, ...) are treated as a single slash, whereas two slashes (//) are left as is:  12:07 $ cd / 12:07 $ pwd / 12:07 $ cd // 12:07 $ pwd // 12:07 $ ls bin  boot  cdrom  dev  etc  home  initrd.img  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var  vmlinuz 12:07 $ cd /// 12:07 $ pwd / 12:07 $ ls bin  boot  cdrom  dev  etc  home  initrd.img  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var  vmlinuz   Usual suspects' versions:  12:07 $ bash --version GNU bash, version 4.3.11(1)-release (x86_64-pc-linux-gnu)  12:20 $ dpkg-query -s coreutils | grep Version Version: 8.21-1ubuntu5


Why did I lose 5 reputation after a "user was removed"?

On my Math.SE account, it says "user was removed" and 5 reputation was deducted. What does this mean?


How can I learn the basics of SharePoint 2013 in a few days?

I have very little knowledge of SharePoint, and want to learn about SharePoint 2013.  Most of the resources that I've found are either about what's new in 2013, or they have a bunch of links to SharePoint 2010.  I also don't have the time to read a thousand page book.  A hundred or so would be fine.  Can anyone recommend a resource (site / book / video / tutorial) for a beginner to learn the basics of SharePoint 2013 in a few days?  I've downloaded a Kindle book, "Getting Started With SharePoint 2013."  It's perfect for absolute beginners, who just want to know how to upload & download documents, but I'm looking for more than that.


Random sized cylinders with no intersection/gaps

I'm trying to find a way to achieve an extruded version of what the image below shows without having to manually scale every cylinder.  I tried particle systems (hair, both vertex and face modes), but I seem to be unable to reach a satisfying compromise between gaps and intersections. My cylinders, in an ideal world, should not intersect at all, and every cylinder must be touchng at least another one.  Here is my reference image:   Any ideas?  Thanks in advance :)


Dynamically created component with aura:id, set as a Facet inside a parent component, is not found when calling find() and passing in aura:id

I would have expected that when a dynamically created lightning component is assigned as another component's attribute of type Aura.Component[],  also referencing it in the parent component's markup by including something like {!v.attributeName}, then the parent component's JavaScript would be able to find that Facet by calling component.find() and passing in the aura:id value of the dynamically created component.  I have attempted this, but the result of the find() call is undefined. Code samples are below.  The parent component with the "stepData" facet... (created to test the stepData component during the development process)  <aura:component > <aura:attribute name="stepData" type="Aura.Component[]"/>  <aura:handler name="completedActionFired" event="c:actionComplete" action="{!c.captureDataResult}" /> <aura:handler name="init" action="{!c.doInit}" value="{!this}"/>  {!v.stepData}   <ltng:require styles="{!$Resource.SLDS202 + '/assets/styles/salesforce-lightning-design-system.css'}"/>  <lightning:layout horizontalAlign="space">     <lightning:layoutItem flexibility="grow" padding="horizontal-medium">         <lightning:button variant="brand" label="Get Object Data" onclick="{! c.getObjectData }" />

         <lightning:button variant="brand" label="Find Component and Get Object Data" onclick="{! c.findObjectData }" />

     </lightning:layoutItem> </lightning:layout> </aura:component>   The parent component controller, where findObjectData() cannot find the Facet component by its aura:id, but getObjectData() can get it by using the attribute name...  ({ doInit : function(component, event, helper) {     var dataMap = {         "testString" : "test value",         "testMap" : {"key1":"value1", "key2":"value2"}     };      var attributes = {         "aura:id" : "stepData",         "dataMap": dataMap     };      $A.createComponents(         [[ "c:stepData", attributes ]],         function(results) {             component.set("v.stepData", results[0]);         }     ); }, findObjectData : function(component, event, helper) {     // try finding component by aura:id     var stepData = component.find("stepData");     if(stepData == null) {         console.log('stepData is not found');         return;     }      // try calling aura:method on stepData     var result = stepData.getObject("testString");     console.log(result); }, getObjectData : function(component, event, helper) {     // get stepData by accessing attribute     var stepData = component.get("v.stepData")[0];     console.log(JSON.stringify(stepData.get("v.dataMap")));      // able to get dataMap attribute from stepData component     var dataMap = stepData.get("v.dataMap");     console.log(dataMap.testString);      // able to call aura:method, but does not return any value to caller     var result = stepData.getObject("testString");     console.log(result); } })   Lightning Component Tree shows the aura:id included on the stepData component reference...    console log shows the "get" button clicked, then the "find" button clicked, where "stepData is not found" indicates find() and aura:id did not successfully locate the dynamically created Facet component.


Evaluating $\tan\left(\sum_{r=1}^{\infty} \arctan\left(\frac{4}{4r^2 +3}\right)\right)$

$$\tan\left(\sum_{r=1}^{\infty} \arctan\left(\dfrac{4}{4r^2  +3}\right)\right)= ? $$   I wrote it in the form:   $$\tan\left(\sum_{r=1}^{\infty} \arctan\left(\dfrac{\dfrac43}{\dfrac{4r^2}{3}  +1}\right)\right)$$ and tried to use:  $$\arctan x- \arctan y = \arctan\left(\dfrac{x-y}{1+xy}\right)$$ but that trick doesn't help here. How to go about solving this problem then?


My Samsung stove is model NE59J7750WS – Nancy 1 hour ago   delete   If I enter 150 I get 1.50 minutes. If I enter 500 I get 5 minutes. If I enter 5 I get 5 minutes. There is nothing on the display panel to show hr. When I push the Cooking Time button this shows up: _ _ _ min. There is an arrow pointing to the right above this. I can't push it or anything. My problem is cannot set for say 5 hours. Samsung told me to enter 5 0 0, but I just get 5 minutes. There is no..... _ hr _ _ min.....like I have seen online in some pics. – Nancy 1 hour ago   delete


I need to Capitalizing first letter of each word in a string using Javascript but ignore if the word is article/preposition.  var string = "at the drop of a hat";   should return  "At the Drop of a Hat"   Please see here that - 1. Every 1st letter of each word is in uppercase 2. 'the' and 'a' being articles were not capitalized 3. 'of' being a preposition was not capitalized 4. 'at' was capitalized even though it is a preposition as it is start of a sentence.  I could do #1 by   string.toLowerCase().replace(/(^[a-z])|(\s[a-z])|([-,:!?\<">';+‘@`€$*&.\\/][a-z])|(\s[а-яё])|(^[а-яё])/g,function(f){return f.toLocaleUpperCase();});   But, this return "At the Drop Of A Hat".  How can I ignore capitalizing articles and prepositions if they're not occurring as first word in a given sentence (i.e. #2,#3 and #4 above)?


What is the oscillating quantity in matter waves?

Every wave is characterised by some periodically changing disturbance. For example, that entity is air pressure for sound waves and electric,magnetic fields for EM waves. What is that disturbance for matter waves?


Assume that $F: \{0,1 \}^n \rightarrow \{0,1 \}^n$ is PRF. Examine if the following functions are PRFs: $$ \begin{align} 1. \, F_1(k,x) &= F(k,x) \oplus x \\ 2. \, F_2(k,x) &= F\left(F(k,0^n), x\right) \\ 3. \, F_3(k,x) &= F\left(F(k,0^n), x\right)|| F(k,x) \end{align} $$ where $||$ denotes concatenation.  Attempt: For $1.$ a standard distinguisher would be: $x_1 \oplus x_2 == y_1 \oplus y_2$, where $x_1, x_2$ are two inputs and $y_1, y_2$ are their outputs respectively. So $F_1$ is not a PRF. For $2.$ I believe that $F(k,0^n) = k'$ acts as a key, so $F_2(k',x) = F(k',x)$ should still be a PRF. For $3.$ I would say that the concatenation of two PRFs would still be a PRF, since you combine two pseudorandom outputs together to yield $F_3$'s output. Can you verify my results?


I'm trying to add an overlay over a div which houses an image. I've seen approaches which add an overlay to background images, but can't seem to figure out why it doesn't work for divs?  Approach:    .featured-image {   height: 338px;   position: relative;   overflow: hidden; }  .overlay {   background-color: rgba(0, 0, 0, 0.6);   width: 100%;   height: 100%;   z-index: 2; }


What is the most practical way to make and include a plot in pdfLaTeX

I often come to a point, where I want a plot of a set of data or just a simple function to be included into my TeX file. The usual naive approach would be to save the plot as a vector or pixel graphic and just import it with the graphicx package.  But this has a downside. Axeslabels for example are often over or undersized.  So another option I tried is gnuplot and the terminal option epslatex. Although this fixes the problem with the axeslabel writing both a vector graphic file and a tex file I found this method to be very impractical when I wanted to change (a small mistake e.g.) in the axeslabel.  So I wanted to know what is the most practical way of creating and including a plot in a LaTeX file making it compatible with size and font of the pdfLaTeX output?  EDIT: The emphasis lies on plotting data points from a file (not plotting an analytic function, thats just to show some limiting behavior).


Simple combination with repetition problem

How many solutions are there to the inequality $x_1 + x_2 + x_3 ≤ 11$, where $x_1, x_2$ and $x_3$ are non-negative integers? [Hint: Introduce an auxiliary variable $x_4$ such that $x_1 + x_2 + x_3$ +  $x_4$ = 11.]  Would my reasoning be correct if I let $x_4 = x_1 + x_2 + x_3, x_4 = 11$  Then proceeded as normally with $14\choose11$? I'm a bit unsure of how the auxiliary variable comes to play.


functional equations with restricted domain

How can I find all discontious solutions of functional equation $f(xy)=f(x)f(y)$ on $[0,1]$. Similar question is to find all solutions of the equation $f(x+y)=f(x)+f(y)$ on $[0,\infty)$. Can we still use Hamel basis?


How to convert a muffin/cupcake recipe to a large muffin recipe

I'm looking at the side of my "breakfast - O - meal" box at a recipe for 12 muffins. The kind you would use with a standard muffin tin. What kind of variation should can I use to make the recipe work in a larger 6 large muffin tin?  I tried this once before with corn bread muffins and they never seemed to be able to bake all the way though. Ideally I would like to try this with some other cupcake / muffin recipes I have too.  So what's the secret? Less liquid? More Egg? My underused large muffin tin needs to know.


Looking For Story About Society of People With Deaf-Blindness

The story I'm thinking of is from the 80s, and it's set in a world where the Great Depression never ended, and so in the "present day" the main character, a wanderer, stumbles upon a society of deaf-mutes. This all came to pass because of a drug that created deformities in children when ingested by pregnant women (like the thalidomide controversy) and so years ago a group of these people set out to create their own society in the middle of nowhere - I think it was in the desert. This man approaches the outskirts of the village and sees a man approaching on a cart. The wanderer only realizes belatedly that the man can't see or hear him. I think the man on the cart might have used a pole so he could feel where the road's boundaries were by whacking it against the fence posts on either side. The wanderer follows the man and encounters a strange sight: braille paths to different buildings. The paths had different patterns that corresponded to particular locations. I believe as a consequence the inhabitants walked barefoot, and I believe they communicated by "writing" in each others' palms. I think the wanderer befriended a little girl, who took him to a cafeteria of sorts in a pitch-black building. That's all I remember.


How to handle rejection from a client and would you bill for work not used?

Would you bill a client even if they end up not using your work? A client of mine had initially liked and chosen one of my designs but then a friend of their friend offered something different that spoke to them more. The client told me to go ahead and bill them as agreed upon but I just feel a bit guilty billing for a design that isn't being used.   At the same time, I am bummed that my work got replaced by another, and I am curious what professional advice you may have for handling rejection.   Thank you in advance!


What's so special about the group axioms?

I've only just begun studying group theory (up to Lagrange) following on from vector spaces and I am still finding them almost frustratingly  arbitrary. I'm not sure what exactly it is about the axioms that motivated them defining groups.  My textbook asks you to list 'common features' of vector spaces and then later defines a set of axioms for vector spaces under addition, scalar multiplication and both, noting that the axioms under addition form an Abelian group. So are groups just a generalisation of vector spaces under any binary operation?  My main problem is that the book notes that 'the axioms may seem rather arbitrary' and links groups with vector spaces but doesn't elaborate.   When introducing groups, you are tasked to complete Cayley tables for the symmetries of an equilateral triangle and square.  Then, similarly to the delivery of vector spaces, notes that the tables have common properties (Closure, Identity, inverse and association) and defines a group as a set of elements under a binary operation that has these features.  So what's so important about these 4 properties? For example, if 1 or 2 the properties were excluded form the  axioms, or we added an extra few properties as axioms how would that cripple the effectiveness of groups?  Are the group axioms ever difficult to work with or do they always work, forgive the crude Littlewood analogy, like a mathematical skeleton key?  What is it about these 4 properties that make groups such a powerful tool in mathematics and physics?  My best guess is that a group is the best way to express our sense of  symmetry and what is symmetric mathematically, but I would prefer some elaboration.


Does Orisa's Supercharge ultimate stack with other damage buffs?

Orisa's ultimate is a damage boost to all allied heroes in line of sight. Does this stack at all with other boosts such as Mercy's right click or with Ana's nano-boost or can all 3 stack together?


"Page Not Found" - is it grammatically correct?

404 - Page Not Found   Every time I see this error message, I think: is it grammatically correct? Because I have the feeling that the verb is missing.


I have Ubuntu 18.04 LTS installed.  I installed Arduino IDE v1.8.5 as a snap with  snap install arduino-mhall119   I have added my user to dial-out group and rebooted:  sudo usermod -a -G dialout $USER  $ groups  username adm dialout cdrom sudo dip plugdev lpadmin sambashare   I connected my Arduino Nano to the laptop, it is detected on port /dev/ttyUSB0 (ch341-uart).  $ ls /dev/ttyUSB0 -al crw-rw---- 1 root dialout 188, 0 авг 13 11:59 /dev/ttyUSB0   I tried to upload the simpliest Blink sketch and get the following errors in the terminal:  $ arduino-mhall119.arduino    avrdude: ser_open(): can't open device "/dev/ttyUSB0": Permission denied   Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.**   Also I have installed arduino 1.8.5 with umake - it can access serial port in usual way.  Note: we already have  here, but the solution was to use , not fix for the Snap.  So my question is: How to make Arduino (Snap) access serial port /dev/ttyUSB0 (or /dev/ttyACM0)?  Update: connecting serial-port to the snap fails with the following message  $ snap connect arduino-mhall119:serial-port  error: snap "core" has no "serial-port" interface slots   Current interfaces are:  $ snap interfaces | grep arduino :home                            arduino-mhall119,gedit,organize-my-files,vlc :network                         arduino-mhall119,gedit,organize-my-files,pulsemixer,vlc :unity7                          arduino-mhall119,gedit,organize-my-files,vlc :x11                             arduino-mhall119,organize-my-files,pulsemixer,vlc -                                arduino-mhall119:serial-port   Changing permissions of serial port to 777 with sudo chmod 777 /dev/ttyUSB0 does not help.  The following do not work too (because of syntax errors):  $ sudo snap connect arduino-mhall119:arduino error: snap "arduino-mhall119" has no plug named "arduino"  $ snap connect arduino-mhall119:/dev/ttyUSB0 error: snap "arduino-mhall119" has no plug named "/dev/ttyUSB0"  $ snap connect arduino-mhall119 error: cannot resolve connection, plug snap name is empty   Information about YAML-manifest:  $ ls -l /snap/arduino-mhall119/current/meta/snap.yaml -rw-r--r-- 1 root root 353 июл 28 00:20 /snap/arduino-mhall119/current/meta/snap.yaml  $ cat /snap/arduino-mhall119/current/meta/snap.yaml |grep -A 12 slots  $ cat /snap/arduino-mhall119/current/meta/snap.yaml |grep -A 5 plug     plugs:     - x11     - unity7     - home     - network     - serial-port


Why is pasting a long one-liner very slow in Vim's insert mode?

My Macbook was stuck yesterday, when I tried to paste 1200 lines of 80 characters to Vim. It was much faster to download the file, and not to paste the text.  I have thought that this problem might be the reason, why internet operators allow slower uploading than downloading.


Convergence of $\zeta(s)$ on $\Re(s)> 1$

I'm aware there are been several similar questions, and some great answers with hints on how to prove this, for example  and .  But I've never really seen a detailed proof of the absolute convergence of the Riemann zeta function in the half-plane $\Re(s)> 1$.  I hope there's interest on a detailed proof of this for reference. Here is my attempt. Please, fill in any detail that might be missing, or point out any mistake!  On $\Re(s)=\sigma> 1$, we have  $$\sum_{n=1}^{\infty}\bigg|\frac{1}{n^s}\bigg|=\sum_{n=1}^{\infty}\frac{1}{n^\sigma}$$  and  $$\frac{1}{n^\sigma}\leq\frac{1}{n^{1+\epsilon}}$$  for any $\epsilon >0$, so by the direct comparison test, if   $$\sum_{n=1}^{\infty}\frac{1}{n^{1+\epsilon}}$$  converges absolutely, then so do $\sum_{n=1}^{\infty}|1/n^s|$ and $\zeta(s)$.  By the integral test, the convergence of $\sum_{n=1}^{\infty}1/n^{1+\epsilon}$ is equivalente to the finitude of the integral  $$\int_1^\infty \frac{1}{n^{1+\epsilon}}=\bigg[-\frac{1}{\epsilon x^\epsilon}\bigg]=\frac{1}{\epsilon}$$  which holds for any $\epsilon < \infty$.  Any correction or improvement is welcomed! Thanks in advance.


My multimeter is rated to 600V.  How can I readily (and safely) use it to measure higher voltages?


Why are these periods the same: a low earth orbit and oscillations through the center of the earth?

Related:   I was learning about GPS satellite orbits and came across that Low Earth Orbits () have a period of about 88 minutes at an altitude of 160 km.  When I took a mechanics course a couple of years ago, we were assigned a problem that assumed that if one could drill a hole through the middle of the Earth and then drop an object into it, what would your period of oscillation be? It just happens to be a number that I remembered and it was 84.5 minutes (see ). So if I fine-tuned the LEO orbit to a vanishing altitude, in theory, I could get its period to be 84.5 minutes as well. Of course, I am ignoring air drag.  My question is: why are these two periods (oscillating through the earth and a zero altitude LEO) the same? I am sure that there is some fundamental physical reason that I am missing here. Help.


How to compute the L^2-distance of a given function to the set of Gaussian functions

I am faced with the following question: given a probability density function $f$ over $\mathbb{R}$ with $\int_{\mathbb{R}}f(x)x^2dx=\sigma^2$ given, I am trying to find the "nearest" Gaussian to $\sqrt{f}$ in $L^2$, i.e. compute $$\inf_{a\in \mathbb{R}, b > 0}\|\sqrt{f}-G_{a,b}\|_2^2$$ where $G_{a,b}(x)=a\exp(-bx^2)$ and the $\|\cdot\|_2$ is the classical $L^2$-norm over $\mathbb{R}.$  If one replaces the $L^2$-distance by the relative entropy $H(f|G_{a,b})$, it is easy to check that the infimum is a minimum given by the centered gaussian with variance $\sigma^2.$ For the $L^2$-distance, it seems more involved......


Periodic task to pull data from API in Django application

In Django application, how can I periodically (say every 10 seconds) make a request to an API?  Right now I have setup a cron that takes care of making an API call and updating the data, but cron has a minute precision. I want the data to be updated every 10 seconds.


Comparison between hierarchical clustering and principal component analysis (PCA)

I just read a article about the comparison between PCA and hierarchical clustering, but I cannot find the strengths and weakness of clustering compared Principal Component Analysis, what about other clustering algorithm? Could anyone provide some details about this?  PCA - creates a low-dimensional representation of the samples from a data set which is optimal in the sense that it contains as much of the variance in the original data set as is possible. PCA also provides a variable representation that is directly connected to the sample representation, and which allows the user to visually find variables that are characteristic for specific sample groups.   Hierarchical clustering - builds a tree-like structure (a dendrogram) where the leaves are the individual objects (samples or variables) and the algorithm successively pairs together objects showing the highest degree of similarity.   Article:


GET n decimal places without round in SQL Server

I need to select just two digits from decimal values in SQL Server  16.987490   --> 16.98 8.0189918   -->  8.01 34.5566901  --> 34.55


velocity of an object after leaving a ramp

at point no. 2 in the diagram, let the object accelerates to a velocity v1 (just along the direction of the slope) due to rolling down the ramp. Now, v1 has a x-component as well as y-component.  Now, my question is:  In the diagram, In between the points no. 2 and 3, the object passes over a horzontal distance.  During this part of motion, which statement of the following is true:  i)  the magnitude of the velocity remains constant, i.e. equal to v1, and only the direction changes.  or, ii) the magnitude of the velocity changes, in such a way, that only the x-component of v1 remains still; whereas, the y-component of v1 completely vanishes,  as soon as the object leaves the ramp and gets onto the horizontal trajectory(between the points marked 2 and 3).


How to bypass "Verify your account" (Factory Reset Protection)

I won a Samsung Galaxy S6 Edge, signed into it with my Google account, played around with it, wiped it, and sold it.  Now the person can't get past setup because it's saying he must login with an account previously synced to the phone.   Is there anything I can do from my side to remove this lock?


Best way to replace tokens in a large text template

I have a large text template which needs tokenized sections replaced by other text. The tokens look something like this: ##USERNAME##.  My first instinct is just to use String.Replace(), but is there a better, more efficient way or is Replace() already optimized for this?


Rolling disk in inclined plane and flat plane?

A disk is rolling (not sliding) in the inclined plane with initial velocity of zero. So there is friction between disk and plane. But when we use the energy conservation rule, we consider as:  gained kinetic energy + gained rotational energy = lost potential energy   So here is there no work against friction? Can anyone explain?    My second question is a practical question. If in the first question there is no work done by friction, explain this scenario: rolling a disk in a plane with initial velocity of $V$, but it stops in a short distance. How this is possible to use energy conservation theory?  lost kinetic energy + lost rotational energy = ?     But most people say here also that work done by friction is zero and air friction stops the disk.  Can anybody explain the work done by friction thing in depth?


python pdb: step into a function called from console

Note: To explain this quickly I'm going to talk about this from the perspective of working in Spyder.  If the a function is called in my code, I can put a break point next to where it's called and then when my code gets to that point I can click the "Step into function.." button to see what happens inside this function.  Suppose I'm at some arbitrary breakpoint and want to see what happens inside a function that's not in my code.  Is there any way to call this function through the pdb console and "step into" said function call?


"Title-only" questions (i.e. questions without body) should be allowed

There is a type of questions like  where the structure is simple enough that a question title surely covers the entire description without further explanation.  Requiring question body for those questions would be redundant and would impose an unnecessary burden on users.  So what I think would be nicer is to have a checkbox, saying "Empty body" to omit the body input.


Is there an OBJ Sequence import script or add-on?

An OBJ sequence is necessary for making complex animations using other 3D programs. I want to use blender and realflow together.  Realflow particle simulations and meshed realflow simulations are in *.bin format.  These images suggest this was at some point in development:     How can I import an OBJ sequence?


Suppose, I have a double value.  double dble = 5.91742691   Now can I get that value with two digits after the point. I mean to say,can I get 5.91 from there programmatically?   One more, suppose,  I want to get an integer from a double value if the double value is X.9XXXXX. Here I mean to say, I want to compare the AFTER-POINT value. For your understanding here dble's AFTER-POINT value is 91742691. How can I do that?


Automatically block identical cross posts

Cross posting is posting exactly the same question on multiple Stack Exchange sites. This is both a common and a highly problematic practice; splintering answers across the network doesn't help people looking for them, which is all our sites are supposed to be about. Very new users, who've yet to learn our strange ways, are the usual culprits of this. I don't think we can blame them, this is (more or less) acceptable behaviour on every other forum on the internet. Furthermore, I don't think expecting them to know they can flag for moderation attention and ask for the question to be migrated is reasonable.  That said, and while cross posting is strongly discouraged, . There are often significant overlaps between sites, and a question may very will be on topic on more than one sites. Cases like this aren't always handled consistently. There are some that believe only one copy of the question should exist, and then there are others that don't find the fact that an on-topic question has been posted elsewhere reason enough to close it.  I'm in the first camp when it comes to questions that have been copy pasted verbatim on multiple sites, and on the second for when the poster has gone through the trouble of tailoring each version to the audience of each site. The first category is, I believe, trivial to detect and it's the one I'd like to see automatically rejected by the system. Even in the rare occasion when a copy pasted question happens to be on topic on both sites, copy pasting your question across the network is . And more often than not, cross posts tend to attract an onslaught of downvotes and/or negatively charged comments, regardless of their topicality. We are doing a very poor job educating our new users about the faults of cross posting, but a fantastic job at chastising them for it.      If outright blocking is out of the question, then I think at least an automated warning is in order. Something along the lines of:      It seems you've already posted this on Chemistry. Also posting it on Arqade may not be such a great idea, questions are very rarely on topic on more than one sites. Please check out Arqade's help center to find more details on what questions this site welcomes.   Thoughts?


Some strange problem occurred to me, when writing a report. I found some similar questions but none of the solutions work for me. Until today, my bibliography worked fine, today everything crashed. I was working with biber but I can not get it working anymore, so I had to switch to bibtex now. Here is my MWE: main.tex: \documentclass[a4paper,11pt]{article}  \usepackage[     backend=biber, % or bibtex     style=phys,     sorting=none, ]{biblatex} \addbibresource{references.bib}  \begin{document}  Hi there, this is me.~\cite{Nobody06}  \printbibliography \end{document}  and the references.bib: @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }   I am using VScode and its recipes (pdflatex-bibtex-pdflatex x2 or latexmk). When using biber as a backend I get undefined references error, while when using bibtex I just get Using fall-back BibTeX(8) backend: (biblatex) functionality may be reduced/unavailable. warning but it compiles successfully. The strangest thing is that both options works fine on overleaf. When I try to compile it by hand in the command line pdflatex main and then biblatex main I still get undefined references. When doing biber main I get Cannot find 'main.bcf', so I am wondering which is the correct combination? Relevant versions: pdfTeX 3.14159265-2.6-1.40.21 (TeX Live 2020) BibTeX 0.99d (TeX Live 2020) kpathsea version 6.3.2 biber version: 2.15


Special functions for non-elementry antiderivatives.

A lot of functions don't have elementary antiderivatives. Quite often I observed new special functions were defined that many of them are written in form of these special functions. Example: the dilogarithm, the airy functions, etc... When I looked up the some information I found that there special functions are defined by these integrals themselves. What is the use of such functions? How do they help us in developing "mathematics"? I am not asking for applications in other fields of science.


I have two classes A and B, where I would like to access the private members of B from A.   class A; // Forward declaration      class B {     friend class A; // A is a friend of B      A a; // error: 'B::a' uses undefined class 'A' private:     int i; };  class A {  public:     B *m_b;      A(B *i_b) : m_b(i_b) {}; // legal access due to friendship };   However, I do not understand why I get the following error: 'B::a' uses undefined class 'A'


Online estimation of variance with limited memory

I am creating a component that aims to calculate the average and variance of a metric associated with events happening during time but with a limited internal memory.  Imagine that the events are visitors entering in a shop and the metric is their age.  During time, my component receives events with the age of each visitor. I don't want my component to memorize the history of each ages. Ideally, I would like a light component storing only: the average A, the variance V and the number of events N.  After each event with age E, I want to update those three values :  N<=N+1 A<=(A*N+E)/(N+1) V<=???   What for V? I am thinking of something like :  V<=(V*N+(E-A)^2)/(N+1)   I know it is not exact as my previous V is using the old A which is no more the average.   Q1 - Is there an exact formula? Q2 - If not, is my proposal a good estimate? Is it biased? Will it converge correctly when N increases? Q3 - Is there a better formula?


First published date vs Issue date: Which do I cite?

I need to cite this paper  . However the year it was first published (2011) and the year it was published in an issue (2012) are different. When I cite it, I will provide the issue and volume numbers, so what year do I cite it by, the first publish year or the first appeared in issue year?


Writing Thesis: Copying from published papers

I'm aware that some institutions offer something that is called 'Thesis by Publication' (sandwich thesis) but that's not available to me. I'm trying to work out what pitfalls there may be to simply copying from papers that I have previously published in order to form large sections of my thesis.  The papers that I've published were largely designed to solve major problems encountered within the larger frame of research, so altogether they should follow a single coherent line of thought.  Must one's own work be cited in a thesis? This would be standard when submitting a paper for publication, but there is a stipulation when publishing papers that that work has not been already published elsewhere, and the same sort of thing does not really crop up with a thesis, does it?  Are there any other potentially pitfalls in this course of action?


Can my boss see what sites I visit when using a vpn from home to the office?

I know my boss could potentially see what sites I visit when I'm at the office if he would want to because I'm connected to the office WiFi or wired connection.  But what about when I'm at home on my own network and I have a VPN connection to the office? Tunnelblick is used for that on my OS X machine.  I think my main issue is that I don't know exactly how the VPN works. I only know that with it I can reach certain websites and svn repositories that are local to the office network. Is every http connection routed to my office or something? Or does it just change my IP maybe? Tunnelblick keeps track how many MB is received and send through the VPN and I'm curious how that exactly works as in how does it know what needs to be send over the VPN, but maybe that's another question on its own. My main concern is whether my boss can see my browsing behaviour that way.


If $J$ is the ideal generated by all idempotents in a prime ideal, then $R/J$ has only trivial idempotents

Let $R$ be a commutative ring with identity, $P$ be a prime ideal in $R$ and define $$X := \lbrace t \in P \mid t^2=t \rbrace. $$ Also let $J$ denote the smallest ideal of $R$ that contains $X$.  Prove that if $$a^2+J=a+J$$ in $R/J$, then $$a+J=J$$ or $$a+J=1+J$$  I am trying to solve this but I am new to algebra (aprox. 3 months), so I generally don't know how to start such questions. So any help is appreciated.


Lubuntu 14.04 b43 missing firmware other solutions haven't worked

I am running Lubuntu 14.04 b43.  Sorry I seem to have the same problem as many others. I have spent the last two or three days looking for other solutions and tried many of them to no avail.  I get the error firmware missing on boot up but it doesn't stay long enough to copy it.    My wireless is BCM4312 LP-PHY 14e4:4315. I am running a completely fresh install of Lubuntu 14.04 on an old Dell Inspiron.  I have tried loads of things including:  Fwcutter and firmware installer eg, and I have tried to install it with this code:  sudo apt-get install linux-firmware-nonfree sudo modprobe -r b43 && sudo modprobe b43   But I have had no luck. Please can you help?


If $\int_{0}^{2} p(x) dx = p(\alpha) + p(\beta)$ for all polynomials of degree at most $3$, what's $3(\alpha - \beta)^2$?

If for some $\alpha , \beta \in \mathbb{R}$ , the integration formula   $\int_{0}^{2} p(x) dx = p(\alpha) + p(\beta)$ , holds for all polynomials $p(x)$ of degree atmost $3$, then the valueof $3(\alpha - \beta)^2 = ?$.  How to approach this question? i thought of taking Polynomial as $x^3$ and i am getting the answer but is there any formal way of doing it without explicitly substituting any polynomial of degree atmost $3$ ?.  Any suggestion , hints , solution ?


The bottom border on the timeline page looks wrong if a title is multiline

<div class="subheader">         <h1>         </h1> </div>   .subheader has style border-bottom: 1px solid #e4e6e8;.  The bottom border should be below the whole title (I guess, the point is to separate the whole title). But the height of this div is hardcoded height: 40px;.  Shouldn't it be like this? (the screenshot with height: 80px;).


Removing a Table from several MXD-Files using ArcPy

I'm trying to remove a certain Table (xlsx-File) from some MXD-Files using python, but I can't finguring out how.   I tried the code sniplet for removing:  import arcpy, os from arcpy import env  arcpy.env.workspace = 'V:/Projects/ZEL'  mxd =arcpy.mapping.MapDocument('V:/Projects/ZEL/test04.mxd')  df=arcpy.mapping.ListDataFrames(mxd, 'u')[0]  for lyr in arcpy.mapping.ListLayers(mxd, '', df):     if lyr.name.lower()=='header_vorlage$':         if lyr.dataSource == 'V:\Projects\ZEL\SHP\Daten_111004\ZEL_LB_Tabelle_V3_2010_2030.xlsx':             arcpy.mapping.RemoveLayer(df, lyr)   mxd.saveACopy('pt.mxd')  print 'fertig'  del mxd   It works, but when I open the new created 'pt.mxd' there is still the symbol of the xlsx-Table with an '!' and you have the option to fix the datasource, because I have removed the path, but not the table...  I hope its not too confusing :)  My question is: Is there a way to remove a xlsx-Sheet from MXD-File without opening?


Im having trouble installing the os in my computer. I get to the screen menu where it gives you the options to install or to test before installing. Whenever i Press install my screen goes black for a few seconds and then turns off completely. Nothing happens after that.  Is there a way to troubleshoot this and find out if this is my pc or the usb? Im really new to all tech stuff too.


I am using the vim latex suite and when I type ... it automatically changes them into \ldots if it is text or \cdots if I am in a math environment. So I thought that \cdots is the "right" thing to use in math.  But I just now saw that using \cdots it looks very odd with something like this:  $b_{1}, b_{2}, \cdots, b_{n}$   In the document it looks simliar to this formatting: b1,b2,... ,bn After the dots and before the comma there is a whitespace. If I use \dots there is no space at all between them.  What would be the right way to do dots? Should I just stay with \cdots but which lookes a little bit strange? Should I use \cdots and add spaceing by myself where I need it?


RSA: If I know n, e, p, and q, how do I calculate d using the extended euclidean algorithm?

After doing a good amount of research, it's become fairly obvious that I ought to be using the extended Euclidean algorithm to calculate d from the data that I already have.  However, this isn't an area of mathematics I'm very familiar with, and the algorithm both takes and outputs multiple integers instead of just one.   So, my question is: Which of the numbers that I already have to I need to input into the algorithm, and of the several numbers it outputs, which is the one I'm looking for?


When going through with learning Grahams number, I got stuck at   $$3↑↑↑3$$  Working it through, we have  $$3↑3=3^3$$ $$3↑↑3=3^{3^3}=3↑(3↑3)$$  As such, it would appear to me that  $$3↑↑↑3=3^{3^{3^3}}=3↑(3↑(3↑3))=3↑(3↑↑)$$  Which is incorrect; the correct answer being  $$3↑↑↑3=3↑↑(3↑↑3)$$  What I'm wanting to know is where the error in the way I've worked it through, and how working $3↑↑(3↑↑3)$ through backwards to $3↑↑↑3$ would look?


Can I use sentence "All rights reserved" on my web page/site or blog with out registering at gov copyright office

I have a query, people are saying that since 1989, every work which is created is automatically copyrighted. Then is it fine to use sentence  All rights reserver and copy right symbol on my website, with out registering at gov copyright office.


I'm going mad about the problem.  I really don't understand why do electron have 1/2 spin number, why they are not actually spinning.  I can accept that the electrons have their own magnetic field, which is certain, but why do they have $\hbar\sqrt3/2$ of angular momentum, and I don't know what the heck is spin number.  I've read the definition of  and  more than a hundred times but there is no betterment. I've smashed my head in my desk more than a hundred times either.  My question is the title. Why can't I just think the spin as rotating?  What I've saw recently,     electron's hypothetical surface would have to be moving faster than the speed of light in order for it to rotate quickly enough to produce the necessary angular momentum.


How to convert cook time and temp from 9" round cake pans to standard cupcakes?

I am making carrot cake "cupcakes" from a recipe meant for round 9" cake pans (3 layers, if that matters).  The cake pans are supposed to cook 25-30 min at 350.  How should I cook the cupcakes?  Thanks!


How is  $Ax + By = C$ the equation of a straight line?

I know the equation, $y = mx + b$ where $m$ is slope and $b$ is $y$-intercept, is a straight line. But I know also that $Ax + By = C$ is a straight line equation, but how does it represent a straight line?


Show that $F\subset Y$ is closed in $Y$ iff $F=Y\;\cap\;H$ where $H\subset X$ is closed in $X$.

I have the following problem:      Let $(X,\tau)$ be a topological space and $(Y,\tau_y)$ be its    subspace, that is $Y\subset X$ and $\tau_y=\{\;A\;\cap\;Y\mid  A\in\tau\;\}$. Let also $F\subset Y$ and $H\subset X$, where $H$ is    closed in $X$. Show that $F=Y\;\cap\;H$ if and only if $F$ is closed   in $Y$.   I solved this problem by assuming that if $F$ is closed then $F=Y\;\cap\;H$, where $H$ is closed in $X$, but I got stuck proving this in the other direction, that is showing that if $F=Y\;\cap\;H$ then $F$ is closed in $Y$.  I tried to do something like this:   Assumption: $F=Y\;\cap\;H$, where $H$ is closed in $X$. If $H$ is closed in $X$ then $X\;\setminus\;H$ is open in $X$ and then $X\;\setminus\;H \in \tau$ which means that $B = (X\;\setminus\;H)\;\cap\;Y\in \tau_y$.  How should I proceed now? Should I investigate the set $B$ now more or what?


How to make a 'Captive Portal' on my mobile hotspot?

Some Wi-Fi networks such as those you find on coffee shops, when connected to, automatically redirect you to a web page where you will need to do something (enter credentials, accept terms of service, etc) in order to access the internet. Is the same possible with an android hotspot?