Does it make any sense to prove $0.999\ldots=1$?

I have read  which contains many proofs of $0.999\ldots=1$.   Background  The main motivation of the question was philosophical and not mathematical. If you read the next section of the post then you will see that I have asked for a "meaning" of the symbol $0.999\ldots$ other than defining it to be $1$. Now here is a epistemological problem and this is mainly the problem from which the question arose. Suppose you know that $1$ is a real number. Now I give you a symbol, say $0.999\ldots$ which from now on I will denote as $x$. Now I ask you whether $x$ is a real number. To answer this, if you define $x=1$ then you are already attributing the properties of $1$ to $x$ among which one is it being a real number without proving whether to $x$ we can indeed attribute the properties of $1$.   A common response to this question has been to define the symbol $x$ as the limit of the sequence $\left(\displaystyle\sum_{i=1}^n \dfrac{9}{10^i}\right)_{n\in\mathbb{N}}$ and then prove that the limit of this sum is indeed $1$. But again the problem is that you are defining the symbol $x$ to be a real number and hence are assuming a priori that the symbol $x$ denotes a real number.  As per the discussion that has been conducted with Simply Beautiful Art let me state my position again in brief,     Also let me say that I do not disallow $0.999…$ to be a real number. My impression that if you assume $0.999…$ to be a real number then there is no sense in proving that $0.999…$ is indeed equal to $1$ because either you define it to be $1$ or you prove the equality as a theorem. But if you are going to use the limit definition of $0.999…$ then what you are a priori assuming it to be a real number which is an assumption that I don't allow. What can be allowed is that $0.999…$ is a number (but not necessarily a real number).    Question  My question is,      Does it make any sense to prove this equality?    Can one give any "meaning" of the symbol $0.999\ldots$ other than defining it to be $1$?


Let $p$ be an odd prime, and let $a$ and $b$ be integers such that $(p, ab) = 1$

Prove that if $p$ divides $a^2+b^2$ , then $ p \equiv \ 1 \pmod 4$.  I know that both $a$ and $b$ are coprimes with $p$ but i dont know what to do next.


I am trying to create the following trigger:      CREATE TRIGGER update_customers AFTER INSERT ON wp_usermeta     FOR EACH ROW      BEGIN             if new.wp_metakey = first_name then insert into test_customer(first_name) values (new.wp_meta_value);     END   I keep getting a 1064 error that says, "You have an error in your SQL syntax; check the manual that corresopons to your MySQL server version for the right syntaxt to use near " at line 5"  What am I doing wrong?


how to make separate list from Json response in python

{   "total": 5,   "start": 0,   "limit": 10,   "results": [     {       "firstName": "stage",       "lastName": "user",       "country": "IN",       "state": "TN",       "city": "Saint Thomas Mount",       "containersSelected": [         "CIEP",         "CIES",         "sthub"       ],       "created": "2020-07-23T03:29:49.394Z",       "updated": "2020-07-23T03:29:59.663Z"     },     {       "firstName": "Automation",       "lastName": "Testing",       "country": "IN",       "state": "TN",       "city": "Saint Thomas Mount",       "containersSelected": [         "CIEP",         "CIES"       ],       "created": "2020-07-22T03:25:00.510Z"     },     {        "firstName": "Test",       "lastName": "elite",       "country": "IN",       "state": "TN",       "city": "Chennai",       "containersSelected": [         "iothub",         "CIEP",         "CIES"       ],       "created": "2020-03-05T06:41:07.884Z"     },     {       "firstName": "Amani",       "lastName": "I",       "country": "IN",       "state": "TG",       "city": "Hyderabad",       "containersSelected": [         "iothub",         "CIEP",         "CIES"       ],       "created": "2019-10-15T06:23:14.857Z"     },     {       "firstName": "Venkatesh",       "lastName": "Chandu",       "country": "IN",       "state": "TG",       "city": "Hyderabad",       "containersSelected": [         "iothub",         "CIEP",         "CIES"       ],       "created": "2019-09-11T09:56:02.540Z"     }   ] }  here I used code was Containerallowedlist = [] data = response.json() for containers in data['results']:     for list in containers['containersSelected']:         Containerallowedlist.append(list)  Output I Got was : ['CIEP', 'CIES', 'sthub', 'CIEP', 'CIES', 'iothub', 'CIEP', 'CIES', 'iothub', 'CIEP', 'CIES', 'iothub', 'CIEP', 'CIES'] But I need output was :  [[‘CIEP', 'CIES', 'sthub’],[’CIEP', 'CIES', 'iothub’],[ 'CIEP', 'CIES', 'iothub’], [‘CIEP', 'CIES', 'iothub’], [‘CIEP', 'CIES’]]


I have a problem with my Ubuntu. I have Ubuntu 14.04 as dual boot (alongside windows 10) on my ACER E5-771G-79VT laptop. My network card is Realtek RTL8723BE Wireless LAN 802.11n PCI-E NIC.  When I start my Linux partition, the wifi works great as it should. But after some time, the pages start to load indefinitely. Meanwhile the signal icon is still full and showing that I am connected to network. After that, nothing can bring wifi back to life. The connection by cable works perfect. Also my windows partition has no problems with network. When i restart Linux i can again use wifi for some time, until it drops again.  Now, i read some other similiar topics, but they didn't helped me, so that is why i am opening my topic.  Thank you


What prevents photons from getting mass from higher order Feynman diagrams

The Higgs boson and gluons have no electric charge and photons couple to charge, so there is no tree level interaction between them and photons.  But what prevents higher order diagrams from contributing a non-zero mass term to the photon, for instance    where a photon couples to some fermion (say an electron, or a top quark) which can interact with the Higgs field.   Or consider that same diagram but with quarks and a gluon interacting between them? Or any higher diagram with even more loops?  I have heard charge conservation depends on gauge invariance, which in turn depends on photons being massless.  So it appears the photon has no mass, and these diagrams must all cancel somehow.  So I'm hoping there is a very nice symmetry explanation for why they all disappear, but if I say "because of gauge invariance" that would be circular logic, so there must be another symmetry at stake here?     What prevents photons from obtaining a mass from high-order self-energy loop diagrams?


Transit time in Ataturk Instanbul airport rescheduled by Turkish airlines

I have a similar question to  , but somewhat different.  My family is flying Lisbon->Istambul->Manila with a transit stop in Ataturk Airport at the end of the month of October. A single ticket covers both legs of the flight.  Turkish airlines just sent a message today, an email in Turkish (God knows why - they speak English), and two SMSes in English telling them their last leg departure was brought forward by 30 minutes.  The point is that they bought that flight because they had 2h20m to do transit, and now they only have 1h50m or less (minus the standard 15 minutes delay for Economy class?), so they should have now 1h35m to change connecting flights.  It is the first time they will be navigating that particular airport.   While the  last question states it is possible to do it; my question is a bit different; what steps do they have to take to minimize the problems, and not for instance going by a route different from the transit one? Is Ataturk easy to navigate, and has it plenty of English signs? Any advice on the route to take inside the airport?  In the meanwhile I also found this related question,  , which gives invaluable tips and states it can be a close call if going through security control.


Adding to a \foreach variable in pgfplots

How can I say sum multiple columns of a table using y expr while also using \foreach  I was hoping something like this would work but apparently it requires some sort of expression evaluation I can't get to work:  \documentclass{article} \usepackage{pgfplots} \pgfplotsset{compat=1.9}  \begin{document} \begin{tikzpicture} \begin{axis}     \foreach \y in {1,3,5,7}         \addplot table[x=Foo, y expr={\thisrowno{\y} + \thisrowno{\y+1}}] {data.csv}; \end{axis} \end{tikzpicture} \end{document}   The data:  Foo John John_a Paul Paul_a George George_a Ringo Ringo_a 1 0.0 37.0 0.00 9.00 0.0 4.0 0.0 12.80 2 16.0 5.0 4.0 1.0 0.6 2.80 0.0 12.80 4 8.0 5.0 2.0 1.0 0.3 2.8 0.0 12.80 8 4.0 5.0 1.0 1.0 0.4 2.8 0.0 12.80 16 2.0 5.0 1.2 1.0 0.4 2.8 0.0 12.80 32 1.0 5.0 1.3 1.0 0.5 2.8 0.0 12.80


Bridge Rectifier Fails When AC Inputs are Shorted

I am working on a design that involves powering a 3.3V microcontroller off a doorbell transformer but I am running into an issue with the bridge rectifier failing when the AC inputs to the rectifier are shorted.    There are two basic parts of the design. First, a full-wave bridge rectifier is used to convert the 21V AC supply from the doorbell transformer to roughly 26V DC. A switching regulator is used to deliver 3.3V for powering the microcontroller. A smoothing capacitor reduces the ripple created by the bridge rectifier. That part of the circuit is working as expected and the microntroller can be powered from the doorbell transformer.  The second part of the circuit is simple. To allow the doorbell to be used normally while powering the microcontroller, a switch shorts the AC inputs. This closes the circuit and powers the solenoid in the doorbell that sounds the chime. The issue I am running into is the bridge rectifier failing when the switch is pressed.  I would really appriciate any insight into why the bridge rectifier fails and how the circuit might be modified to prevent the failure.  Bridge rectifier datasheet:


I really enjoyed that site. I've only posted on it once, but I enjoyed seeing other people's posts and appreciated reading about entrepreneurial dilemmas.


I've been looking at some proofs of derivatives of functions and the teacher who made it used this in his proof:  $$ \lim_{u \to 0}((1+u)^{\frac{1}{u}})=e\ $$  I can see that this is true by substituting small values for u but why is this true and how do I prove it?  I would thank you if you could explain on more of a basic level, since I am quite a beginner here :)  Thanks in advance!  PS Sorry for my sloppy Enlgish


I think there is a way to do an inside radius, and an outside radius, but how? I want to have a spawnpoint, where @a[r=30] is in gamemode a, and everyone outside is gamemode s. How would I write this?


Convex set $A$ in $\mathbb{R}^n$ iff for every $ x,y\in A,0\le\lambda\le1$, then $\lambda x+(1-\lambda)y\in A$.  $U$ is regular open set iff $A$ is open and $int(cl(A)) = A$.  Is convex open set in $\mathbb{R}^n$ is regular?


Can a home motion detector work through frosted or clear glass?

I'm thinking of installing a motion detector inside an existing recessed fixture over my front door in order to illuminate the stairs and door lock at night. Home Depot sells a small sensor that can be installed between the socket and bulb but nobody has been able to tell me if the frosted glass cover will block the sensor.


Why don't lens mount adapters have the same effect as extension tubes?

I use a Metabones adapter for Canon lenses on a Sony body. Why doesn't the lens adapter, which sets the lens further from the sensor, have the same effect as using extension tubes, allowing closer focus?


Profile picture is overflowing on network profile

Have a look at . The profile picture is overflowing.    While his  looks fine. Please fix this.


System says I flagged as "not welcome", but I didn't

I flagged a question as spam, and wanted to add a second, custom flag to let moderators and developers know about a repeating pattern I was seeing. When I clicked the flag link to add the second flag, I got this dialog:    It says that I already raised both a spam flag and a not welcome flag, but that's not true; I just raised one flag, a spam flag. It probably does make sense to disable both options when either type of flag was already raised, but the messages stating that I raised two flags are wrong and confusing.


Bibtex does not work properly "There were undefined references"

I am new to Latex and I try to include references in my document:  I use Texmaker and I export the .bib file out of Mendeley.  The file test.tex looks like the following:  \documentclass[10pt,a4paper]{article} \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \begin{document}   \bibliography{test} \bibliographystyle{plane}   \section{test}  test  \cite{Ref1}  \end{document}   test.bib looks like the following:  @article{Ref1, author = {test,1}, number = {5}, pages = {1--16}, title = {{Journal ∗}}, volume = {16}, year = {2006} }   Everything is in the same folder, I tried to compile it twice - I tried to change the bibliographystyle, etc. nothing works. Via autocomplete Texmaker suggest me Ref1.     Error: "Citation "Ref1" on page1 undefined.   Hopefully someone can help me!


geometry package - paperwidth and paperheight aren't accurate

recognize this simple example:  \documentclass[]{article} \usepackage[paperwidth=612.0pt, paperheight=792.0pt]{geometry}  \begin{document} Hello World \end{document}   I compiled it with pdflatex. Additionally I wrote this small Java-Programm (using the iText library):  PdfReader reader = new PdfReader("example.pdf"); Rectangle psize = reader.getPageSize(1); System.out.println(psize.getHeight()); System.out.println(psize.getWidth());   The result:  Height: 789.041 Width: 609.714   Why is the paperwidth and paperheight different to the tex?


Publish new image to the website, but need to F5 to show the new effect

Everytime I update new image like 'index.gif' to website without changing image's name, the user could not see the update until they fresh the browser by F5 to clean the image cache.  It is same as updating css, but I usually change css link version like:  <link href="index.css?ver=xxxxxx" rel="stylesheet" type="text/css" />   Because there is only one reference to this css, so I can change it easily. In contrast, there are so many refers to one image, so I'm frustrated for changing all the links to new image.  So is there any easy way to solve my problem?


degree of freedom of a rigid body 5 or 6?

I'm confused here. I have a three particle (rigid) system. What would be the degree of freedom? I found out five. 3 coordinates for center of mass and 2 for describing orientation. But we have only three constraints, i.e. three equations that reduce 9 coordinates by 3, 9 - 3 = 6, which gives 6 degrees of freedom?? Did I miss something above?


I have several parent equations each with more than 30 subequations. When I write it normally with subequation command, I receive "counter too large" error.  I found out that there is a package named "alphalph" which can solve these numberings with different styles. I have seen  for subequations in StackExchange, but it doesn't work for me! I still get the error!! (since I want to refer to them later, I need to label them too).  Does anybody know where the problem is, or suggest an alternative?  Thanks


Is there a list of android system status bar icons?

I'm not sure what some of the status bar icons mean on my Android Nexus 5 device (I'm referring to the icons in top right of screen, adjacent to the time). I've googled frequently but I keep getting back a list of icons to use in app development.   I'm looking for a list of the system status bar icons and an explanation of the meaning of that icon. I'm interested specifically in the vanilla Android Lollipop OS on Nexus.


Is help still valid when using movement after it?

In a situation were a rogue uses help as action, disengage as bonus action and movement to move away, does he still help another PC to attack the target with adv?


Best way to put commas into large numbers

I've started a new job and it involves looking at a bunch of big numbers. Is there an easy way to add commas to an int or decimal field to make it readable?  For example, SQL Server outputs the column on the left, but for my own sanity, I need it to look like the one on the right:  2036150 -> 2,036,150     ...or would I have to write some heinous   left(right(vandalized_data),6),3) + ',' + right(left(vandalized_data),6),3)   function?  The perfect thing would be commas in the display grid, then plain integers in the output.


UK general visitor visa refused for funds evidence?

My visa was rejected because I failed to provide bank statements. I'm a drop-out student and at present I don't work and I don't study, so I don't have any account balance.  I've mentioned in my application that I'm supported by my father.  I'm visiting the UK to visit my friend for 5 days. I have provided my friend's invitation letter, visa, passport and bank statements. I have provided my hotel booking also.  I have provided my father's income tax return documents. But I failed to provide his bank statements. If I provide bank statements will I get an entry clearance?


Let Nl and N2 be 6 X 6 nilpotent matrices over the field F. Suppose that N1 and N2 have the same minimal polynomial and the same nullity. Prove that N1 and N2 are similar. Show that this is not true for 7 X 7 nilpotent matrices.  Well, if Nl and N2 are 6 X 6 nilpotent matrices, the characteristic polynomial of them, are p1(x)=p2(x)=x^6 and the minimal m1(x)=m2(x)=x^i with i=1,...,6. As these matrices has same nullity, (call it "s") then rank(N1)=rank(N2)=6-s. Now, should i do?  Should i fix the minimal and consider the possibilities for the rank and confirming that all have the same Jordan form?


Is ${x+\frac 1x}$ equal an integer number, only $x=1$ ? If, $x>0$.

I'm looking for this question in MSE. But,I could not find a similar one.     Is ${x+\dfrac 1x}$ equal an integer number, only $x=1$ ?   If, $x>0$.   I can prove this only when $x\in \mathbb{N}$ but not for $x \in \mathbb{R}^+$.  Remark: the duplicate link just answer the case where $x \in \mathbb{Q}$.


How do I set right alignment in a longtable column with a fixed width?  I have \begin{longtable}{p{3cm}p{8cm}}  and I'd like my first column to be aligned on the right.


I have two render camera objects in the scene, about to be three, I'd like to know how to switch between them as when I hit zero, it only enters the view of my frontal camera(the first one I placed.) is it possible to switch between them?


Should a button become lighter or darker on hover?

We're having a discussion in the office about whether a button should become lighter or darker when a user hovers over it.   Here are some examples from the field:  Apple "Buy Now" button (Second is hover, third is depressed) -     Twitter Bootstrap -    (Unselected)   (Hover)  Github homepage - github.com      The button on FogBugz homepage goes from yellow to slightly lighter yellow. The buttons on Optimizely and Visual Website Optimizer hardly change.  Amazon's "Buy Now" button doesn't do anything when you hover over it (besides change to a pointer cursor). The colored buttons in Google's new interface (see Gmail or Calendar) go slightly darker when you hover over them.  Finally here is our button:    Should your button become lighter or darker when you hover over it? What else should you consider? Does anyone have data on whether the hover effect matters for conversions?


Delete files older than X days from remote FTP server

My backups are stored on remote FTP server. I'm looking for a universal way to clean-up the FTP directory using bash or python.  Any help would be appreciated.  Edited: I have only FTP access to the server.  I need to cleanup the directory via remotely logging in via FTP


Is there a way to use a nerd font such as Iosevka in the TTY for Ubuntu Server?

If not, what would be the lowest impact to get a nerd font working?


To show that the only nonempty subset of $\Bbb R$ which is both open and closed in $\Bbb R$ is $\Bbb R$.  Let $A$ be a non empty subset of $\Bbb R$ which is both open and closed. Let $x \in A$. Then $(x- \epsilon ,x+ \epsilon) \subset A$ for some $\epsilon >0$. Then how to bring the contradiction by putting in the fact that $A$ cannot be simultaneously open and closed!!


Content block doesn't show when query is added to the URL

I have a Drupal 7 page where some of my content blocks don't show up, if there is a query added to the URL.  Say my block is main_content, and it is shown all all pages except the listed ones, where no page is listed; the block appears correctly on on www.mydomain.com, but not on www.mydomain.com?gclid=xxx.  This is an issue for me because Google AdWords banners are linking to my page with a query attribute, and then the page does not display correctly.  What could be the issue here?


Set WPF UserControl properties to a Control inside it

So, for example, I made a UserControl to improve default WPF ProgressBar, sth like ProgressBarPlus or whatever, so I need to have all property values of the UserControl set to a ProgressBar inside it, there should be some way other than adding each property of ProgressBar (Value, Maximum, SmallChange, LargeChange etc...) to my UserControl manually, then set my ProgressBar properties according to my UserControl properties.  To sum it up, I need to make my UserControl act exactly as a ProgressBar (its properties and events) but with a few controls added to it to make its functionality better.  Couldn't find anything on google, any ideas?


People with high enough reputation should not receive automated behavior suggestions

My reputation in StackOverflow is among the top 1% of users. I'm not as active as I used to be, but I still come back to the site from time to time. Unfortunately, I find that when I do return, I get a message "Welcome back, you can upvote!" To be frank, this reminds me of the paperclip on Word 98. I am well aware that I can upvote (or edit comments, or delete posts, or downvote, or undelete posts, or flag, or... pretty much everything)  If reputation could we either get rid of the message entirely or at least get rid of the "you can vote" part of the message?  While I'm at it, I would also appreciate it if a high rep level meant that I could skip the "You've down voted someone! Please add a suggestion to try to make it better." Once again, I am more than aware how the system works, I do not need JavaScript annoying me about it.


Proof of the inequality $\frac{a}{b+c}+\frac{b}{a+c}+\frac{c}{a+b} \geq \frac{3}{2}$

I am currently attempting to prove the following inequality   $\dfrac{a}{b+c}+\dfrac{b}{a+c}+\dfrac{c}{a+b} \geq \dfrac{3}{2}$ for all $ a,b,c>0$   My instinctive plan of attack is to use the AM/GM inequality with $x_1=\dfrac{a}{b+c}$ etc.  Using that I get this  $\dfrac{a}{b+c}+\dfrac{b}{a+c}+\dfrac{c}{a+b} \geq 3\times \sqrt[3]{\dfrac{abc}{(a+b)(b+c)(a+c)}}$   From here, I used the fact that $(a+b)(b+c)(a+c)\geq 8abc$, which can be easily proven by considering that $a+b\geq 2\sqrt{ab}$   But by using this, I get the following...  $\dfrac{a}{b+c}+\dfrac{b}{a+c}+\dfrac{c}{a+b} \geq 3\times \sqrt[3]{\dfrac{abc}{(a+b)(b+c)(a+c)}} \leq 3 \times \sqrt[3]{\dfrac{abc}{8abc}} = \dfrac{3}{2}$   Everything seems so perfect because I get the value $\dfrac{3}{2}$ as required, but this method isn't valid due to the change in direction! What is going on?  Is there a way of proving this inequality otherwise then?


Suppose $X_1,X_2,\cdots,X_n$ are iid uniform random variables on $[a,b]$, what is the distribution of $$Y_n=\frac{\max_{1\le i\le n}X_i+\min_{1\le i\le n}X_i}{2}?$$


Hottest tea during your breakfast problem

Suppose you are having breakfast and you like to drink your tea with 50% milk, 50% tea. You like to drink your tea as hot as possible, but your friend already filled your cup with tea, so it's already cooling off. Drinking it immediately is not an option though, because before you drink your tea you always eat your cornflakes, which roughly takes 10 minutes. What will theoretically result in the lowest temperature drop after 10 minutes? Pouring the milk into the cup immediately and drink after 10 minutes or wait for 10 minutes before pouring in the milk. Or perhaps somewhere in between?  I think there is two sides to this problem. Pouring the milk into the cup immediately will result in a very big temperature drop, because, since there is as much milk as tea, the temperatures will be averaged out. However the temperature will not drop as much in the next ten minutes, because the temperature is closer to the room temperature it is in. This goes both ways.  So here is my question: Which method will result in the lowest temperature drop? Will this method always result in the lowest temperature drop? Why?  EDIT: Some extra information is needed to answer the question. The temperatures of the milk, room and tea are 5, 20 and 80 Celsius. Everything else is just normal. Just a normal room, a normal cup.


Can you make it so that MathJax appears on mobile on the list of all open questions instead of raw LaTeX?

Is there a way to make it so that equations and mathematical type looks formatted on mobile (iOS) devices on the main page (where the questions are)? Thanks!


Question is to Evaluate $$\sum_{n=1}^{\infty}\arctan (\frac{2}{n^2})$$  What I have done so far is i tried taking sequence of patial sums.  $S_1=\arctan (\frac{2}{1})$  $S_2=\arctan (\frac{2}{1})+\arctan (\frac{2}{2^2})=\arctan 2+\arctan (\frac{1}{2})$  $\tan S_2=\tan(\arctan 2+\arctan (\frac{1}{2}))=\frac{***}{1-2.\frac{1}{2}}=\frac{***}{0}\Rightarrow S_2 =\frac{\pi}{2}$  Now there is a problem for $S_3$  $S_3=\arctan (\frac{2}{1})+\arctan (\frac{2}{2^2})+\arctan (\frac{2}{2^3})=\frac{\pi}{2}++\arctan (\frac{2}{2^3})$  I can not apply $\tan$ function on both sides as this would again give me :  $\tan S_3=\tan(\frac{\pi}{2}+\arctan (\frac{2}{2^3}))=\frac{\infty+**}{1-\infty**}$ which does not makes much sense.  I would be thankful if some one can help me with this.  Thank you.  P.S : I would be thankful if some one can suggest me another way to solve this than that of the originally posted solution in quoted duplicate...


What do empty curly brackets mean in bash?

I understand all of this but lose it when i get to the 7th line starting with find.  i don't understand the -exec cp {}. I understand that this is executing the copy command but I don't understand what the brackets{} are doing, especially if they are empty?  This entire snippet is from a book im reading.  # This script prompts to backup files and location # The files will search on $HOME dir and will only backup files to same $HOME dir. read -p "Which file types would you like to backup? >>: " file_suffix read -p "Which directory would you like to backup to? >>: " dir_name # creates a directory if it does not currently exist test -d $HOME/$dir_name || mkdir -m 700 $HOME/$dir_name # search criteria ie .sh . The -path, -prune and -o options are to exclude the back directory from the backup. find $HOME -path $HOME/$dir_name -prune -o -name "*$file_suffix" -exec cp {} $HOME/$dir_name/ \; exit 0


How to run many instances of Google Chrome in full screen on multi monitor system

I need to run multiple instances of Google Chrome. Each instance must run on different monitor in a multi monitor system (Windows OS) but in full screen without any buttons or menus.  I tried several combination of switches but without luck  --start-fullscreen  --window-position=10,10 -window-size=800,600  --kiosk   --new-window  The Kiosk mode works but If I try to run the next instance it will go again on the  primary screen.  Is there a way to run the Kiosk mode (preffered) or FullScreen mode  of different Windowed Chrome instances in a multimonitor system ?  Probably if nothing works I would need to start each instance programmatically and  send F11 keys to each window. This will work but it is some kind of hacking solution.  I am interested to know if there is some gracefull way to tell to Chrome "run this instance in a window in full screen or kiosk mode."


I want to use ReadProcessMemory function to fill this struct.      [StructLayout(LayoutKind.Explicit)] public struct WinMineGameStruct {     [FieldOffset(0x118)]     public Int32 xPressed;     [FieldOffset(0x118)]     public Int32 yPressed;     [FieldOffset(0x140)]     public Int32 MouseDown;     [FieldOffset(0x160)]     public Int32 GameStatus;     [FieldOffset(0x164)]     public Int32 IsInGame;     [FieldOffset(0x194)]     public Int32 MinesLeft;     [FieldOffset(0x330)]     public Int32 LevelMines;     [FieldOffset(0x334)]     public Int32 Colls;     [FieldOffset(0x338)]     public Int32 Rows;     [FieldOffset(0x6a0)]     public Int32 GameType;     [FieldOffset(0x6cc)]     public Int32 EasyBestScore;     [FieldOffset(0x6d0)]     public Int32 MediumBestScore;     [FieldOffset(0x6d4)]     public Int32 HardBestScore;     [FieldOffset(0x6d8)]     [MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)]     public Char[] PlayerEasyName;     [FieldOffset(0x718)]     [MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)]     public Char[] PlayerMediumName;     [FieldOffset(0x758)]     [MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)]     public Char[] PlayerHardName;     [FieldOffset(0x798)]     public Int32 NumLastHitDiscovered;     [FieldOffset(0x79c)]     public Int32 TimePlayed;     [FieldOffset(0x7a4)]     public Int32 DiscoveredFields; }   I know how to read byte array, int, string, short, and so on. I want to know how to convert byte array to this struct.


Is the set $T$ of all sequences of rational numbers which converge to the number $3$ countable or uncountable?

I have been trying to solve the following problem:     How many rational sequences exist for $\lim_{n\to 3}$   My intuition:   I believe the set $T$ is countable. It can be shown (in more ways than one) that $\mathbb{Q}$ is a countable set. The set $T$ is a subset of $\mathbb{Q}$ and must therefore be countable.  Is my intuition correct?


Proof of relations involving function operators

I need proof this property of operators, where should I start?, A and B are operators, and $$\hat{e}Be^{-A} = B+[A,B]+ \frac{1}{2!}[A,[A,B]]+\frac{1}{3!}[A,[A,[A,B]]]+...  $$ Thx


Why x_\text{...} generate error when inlined but ok in display mode with tex4ht?

I can't understand why \tau = x_\text{average} work ok in display mode math but gives an error when inline.  This error shows up only with tex4ht, not pdflatex.  MWE  \documentclass[12pt]{article} \usepackage{amsmath} \begin{document} $\tau = x_\text{average}$ \end{document}   Now typing  htlatex foo.tex   gives  (/usr/local/texlive/2014/texmf-dist/tex/generic/tex4ht/html4.4ht) (/usr/local/texlive/2014/texmf-dist/tex/generic/tex4ht/html4-math.4ht)) (./foo.aux) ! Argument of \n:text@: has an extra }. <inserted text>                  \par  l.6 $\tau = x_\text{                     average}$ ?    But this compiles ok  \documentclass[12pt]{article} \usepackage{amsmath} \begin{document} \[     \tau = x_\text{average}  \] \end{document}   I am using tex4ht with tex live 2014 on linux   *File List*  article.cls    2014/09/29 v1.4h Standard LaTeX document class   size12.clo    2014/09/29 v1.4h Standard LaTeX file (size option)  amsmath.sty    2013/01/14 v2.14 AMS math features  amstext.sty    2000/06/29 v2.01   amsgen.sty    1999/11/30 v2.0   amsbsy.sty    1999/11/29 v1.2d   amsopn.sty    1999/12/14 v2.01 operator names


Difference in symmetries of Second quantized and First quantized Hamiltonian

The following is stated in (among others) the articles    - Shinsei Ryu, Andreas Schnyder, Akira Furusaki, Andreas Ludwig  - Ching-Kai Chiu, Jeffrey C.Y. Teo, Andreas P. Schnyder, Shinsei Ryu   The three discrete symmetries Time reversal symmetry ($T$), Particle-hole symmetry ($C$) and Chiral symmetry ($S$) all commute (are real symmetries) of the full second quantized Hamiltonian, $$\hat{H}=\sum_{A,B}\Psi_A^\dagger \mathcal{H}_{AB}\Psi_B. $$ That is, $$[\hat{T},\hat{H}]=[\hat{C},\hat{H}]=[\hat{S},\hat{H}]=0.\;\;\;\;\;\;\; (1)$$ They go on to claim that, $\hat{C}$ and $\hat{S}$ are not real symmetries in the "classical" sense of the first quantized Hamiltonian $\mathcal{H}$. In fact, the first quantized Hamiltonians obey,  $$[T,\mathcal{H}]=\{C,\mathcal{H}\}=\{S,\mathcal{H}\}=0. \;\;\;\;\;\; (2)$$ How can I prove that imposing Eq. (1) implies Eq. (2)?


I downloaded and installed Java 1.7 from .  When I run the Java Control Panel, I could check I have it correctly installed.     However, when I checked the Java version from command line, the version that I use is Java 1.6.  java -version java version "1.6.0_33" Java(TM) SE Runtime Environment (build 1.6.0_33-b03-424-11M3720) Java HotSpot(TM) 64-Bit Server VM (build 20.8-b03-424, mixed mode)   The system directory doesn't have the 1.7.    What's wrong with this?   Where is the Java 1.7 is installed? How can I make the Java 1.7 as default Java?


A simple proof (hopefully) for $2^x \neq 0$

I'm pretty confident that this is a valid proof, but I still need people who are better than me to confirm it, here's the proposition: Proposition: $2^x=0$ has no real solutions. Proof: By contradiction Assume $2^x=0$ has a real solution  (i.e. $2^x=0$ when $x=\alpha$), then $$2^\alpha=0 \implies 2^\alpha \cdot 2=0 \implies 2^{\alpha+1}=2^\alpha \implies \alpha=\alpha+1$$ Which is a contradiction because $\alpha=\alpha+1$ has no real solutions. $\therefore 2^x=0$ has no real solutions.


Different ways finding the derivative of $\sin$ and $\cos$.

I am looking for different ways of differentiating $\sin$ and $\cos$, especially when using the geometric definition, but ways that use other defintions are also welcome.   Please include the definition you are using.   I think there are several ways to do this I didn't find, that make clever use of trigonometric identities or derivative facts. I am looking for these for several reasons. Firstly, it is just interesting to see. Secondly, there may be interesting techniques that can also be applied in a clever way to other derivative problems. It is also interesting to see how proofs can come form completely different fields of mathematics or even from physics.  I have included several solutions in the answers.


How do I set the default file association in Ubuntu Nautilus to something that is not listed in the Open With tab?

There used to be an option for adding unlisted commands, but it seems to be gone in Unity. Does anyone know how to do that now?


Finding Jordan basis of a matrix $(4\times 4)$

I'm facing a problem finding a Jordan basis for this ($4 \times 4$) matrix: $$\left(\begin{matrix}3&-1&1&7\\9&-3&-7&-1\\0&0&4&-8\\0&0&2&-4\end{matrix}\right)$$  I know that the characteristic polynomial is $\lambda^4=0$ and it's minimal polynomial is: $x^2$. This means that $(A-0I)^2=0$. Also the Jordan form for this matrix is $$\left(\begin{matrix}0&1&0&0\\0&0&1&0\\0&0&0&1\\0&0&0&0\end{matrix}\right)$$ But I'm facing problems in the general procedure to compute the basis for such a matrix?


Changing a global variable inside a function

I have the following code:  curtains = 0  def bedroom_curtains_open():     print ("You open your curtains to reveal that it is very dark out.")     print ("It looks to be about 2am, what woke you?")     curtains = 1     bedroom_up()   This, however doesn't change the variable curtains to 1, why is this?


Understanding Euclid's proof that the number of primes is infinite.

In Euclid's proof, if $p_1, p_2, \dots, p_n$ are the only primes then $p_1 \times p_2 \times \dots \times p_n + 1$ is not divisible by any of $p_1, p_2, \dots, p_n$ (because of some algebraic facts), which makes another prime and is a contradiction.   The proof makes sense logically, and I tried some numerical examples to "feel" the proof better but...  $2 \times 3 \times 5\times 7\times 11\times 13+1$ is not a prime! $2 \times 3 \times 5\times 7\times 11\times 13 \times 17+1$ is also not prime! Why is the general case proof is not working for these examples?


Any field that contains the integers contains the rationals as a subfield

It has pretty much been answered here,   but I don't really understand how it was done. Also, is there another, simpler way to show this than the way in the question above?


Is it OK to copy parts of an answer from one SE site to an answer on another SE site?

I flagged  earlier with a custom reason explaining that the code had simply been copied from an answer to a similar question on another SE website. The author of the newer answer has provided a link to the original answer (probably important to know).  The flag was declined (no evidence etc.) so I just wanted to get the official policy on this.  I'm now under the impression that copying answers from one SE site to another is absolutely fine, as long as a reference is provided to the original answer.  Could someone confirm if this thinking is true or false? Or is it just a judgement call?


Define $R(m,n,k)$ and show that $R(3; 3; 3) = 17$  How would I solve this? I am slowly starting to wrap my head around 2 variable ramsey numbers but not quite on 3. Here I know that R(m,n,k) are vertexes which mean there are 17 vertices and that there are 3 different colored edges. And each of these colors create a monochromatic triangle of the m,n,k colors on a graph. How would I go about showing R(3,3,3) = 17.   Thank you for any guidance.


Are people capable of generating a random number?

Let's say you tell me to produce randomly a number from 1-100, and I choose the number 47. Can it be said that there is a specific reason I chose the number 47, and that it is not completely random? By random I mean that there is absolutely no reason this number in particular was chosen.    It seems odd to me, since it seems like since I have applied conscious effort to produce or choose a number within that range, or even without range, that it can't be truly random, but there might be a reason why I chose that number amongst the many others I could have chosen.  I guess the general question, which I'm interested to know if any philosophers in the past have discussed, is whether our thoughts are necessarily based on prior thoughts, or if thoughts can be truly spontaneous and random?


i have class like this   if ( ! class_exists( 'My_class' ) ) {     class My_class {         public function __construct() {             add_action( 'woocommerce_shop_loop_item_title', array( $this, 'change_title' ), 10 );         }          public function change_title() {             echo 'The title';         }     } }  return new My_class();   I trying to remove_action change_title by using   remove_action( 'woocommerce_before_shop_loop_item_title', array( 'My_class', 'change_title' ), 10 ); // or remove_action( 'woocommerce_before_shop_loop_item_title', 10 );   But it does not work because I don't really understand PHP OOP. How can I do that, is it possible?  And can i remove it via a plugin?  Thanks


Will it harm my 9v rechargeable battery if the +ve and -ve terminals are connected to each other

By mistake, the positive and negative terminal of a 9v rechargeable battery were connected to each other by me, and when I noticed it, I quickly removed it and the battery became hot a little. Did it caused any harm to my battery, Or should I use the battery or is it damaged now? Will it explode if I put it to charging now?


Is there a law that you can add or multiply to both sides of an equation?

It seems that given a statement $a = b$, that $a + c = b + c$ is assumed also to be true.  Why isn't this an axiom of arithmetic, like the commutative law or associative law?  Or is it a consequence of some other axiom of arithmetic?  Thanks!  Edit: I understand the intuitive meaning of equality. Answers that stated that $a = b$ means they are the same number or object make sense but what I'm asking is if there is an explicit law of replacement that allows us to make this intuitive truth a valid mathematical deduction. For example is there an axiom of Peano's Axioms or some other axiomatic system that allows for adding or multiplying both sides of an equation by the same number?   In all the texts I've come across I've never seen an axiom that states if $a = b$ then $a + c = b + c$. I have however seen if $a < b$ then $a + c < b + c$. In my view $<$ and $=$ are similar so the absence of a definition for equality is strange.


Batch processing LiDAR files (.las to raster) with PyQGIS?

for layers in glob.glob("*.las"):         processing.runalg("grass7:r.in.lidar", "input_las",5,1,"",1,100,"","",5,"","",False,True,True,"331289.57265,337990.42735,4558790.0,4560890.0",0,layers+"E:/las_new/.tif")      {'output': 'PNOA_2016_CAT_huso31_346-4560.lasE:/las_new/.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4562.lasE:/las_new/.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4564.lasE:/las_new/.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4566.lasE:/las_new/.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4568.lasE:/las_new/.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4570.lasE:/las_new/.tif'}   output_ras=("E:/las_Ras")   for layers in glob.glob("*.las"):     processing.runalg("grass7:r.in.lidar", "input_las",5,1,"",1,100,"","",5,"","",False,True,True,"331289.57265,337990.42735,4558790.0,4560890.0",0,layers+"output_ras.tif")      {'output': 'PNOA_2016_CAT_huso31_346-4560.lasoutput_ras.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4562.lasoutput_ras.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4564.lasoutput_ras.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4566.lasoutput_ras.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4568.lasoutput_ras.tif'}   {'output': 'PNOA_2016_CAT_huso31_346-4570.lasoutput_ras.tif'}     for layers in glob.glob("*.las"):     processing.runalg("grass7:r.in.lidar", "input_las",5,1,"",1,100,"","",5,"","",False,True,True,"331289.57265,337990.42735,4558790.0,4560890.0",0,"output_ras.tif")      {'output': 'output_ras.tif'}   {'output': 'output_ras.tif'}   {'output': 'output_ras.tif'}   {'output': 'output_ras.tif'}   {'output': 'output_ras.tif'}   {'output': 'output_ras.tif'}   I would like to batch process many LAS files to rasters using the PyQGIS algorithm. As you can see in the code, I think the final problem is with the output. It does not write the files out to my defined output pathway as tif files. Also how can I make sure the naming of output rasters are according to the original LAS they are generated from? What am I doing wrong here? Not a pro at Python. Started 3 days ago.


Can I make a file always load from server?

In my website I have changed css of a page and these changes are not reflecting instantly when I open that page in browser. It showing old css styles because browser has a saved copy of my css file and it does not reflecting the new changes.  The new changes are loading in the page when I load the page by pressing (CTRL+F5) then the changes I have done are reflected in the page. So can I make css file which always loaded from server and the changes done that page can reflect immediately on the page.


Difference between list() and dict() with generators

So what's the explanation behind the difference between list() and dict() in the following example:  glist = (x for x in (1, 2, 3)) print(list(glist)) print(list(glist))  gdict = {x:y for x,y in ((1,11), (2,22), (3,33))} print(dict(gdict)) print(dict(gdict))  >>> [1, 2, 3] [] {1: 11, 2: 22, 3: 33} {1: 11, 2: 22, 3: 33}


Cannot connect to X server :0.0 as superuser

When I am online, I get following error and the tool does not start:  [root@dhcppc9 lin64]# ./ise No protocol specified _pn: cannot connect to X server :0.0   But everything is OK when I am not a superuser. Why that?  Edit  [root@dhcppc9 lin64]# export $(dbus-launch) No protocol specified   any suggestion?  Also   [root@dhcppc9 lin64]# xhost [+] No protocol specified xhost:  unable to open display ":0.0"


Dissolving polygon shapefile in Python without ArcPy?

I need to figure out a way to dissolve a polygon in Python using other modules besides ArcPy. I've been using the Python GDAL/OGR for merging shapefiles but I don't see anything to dissolve a polygon. I've been looking into Shapley, Fiona and Pyshp.  I also don't want to use qgis, as importing the qgis.core module gives my script problems.   Any ideas?  **EDIT I'm trying the Fiona approach but am having a hard time configuring it. I installed a .whl of it and it appears to install but when I run something it crashes Python saying   'This application has requested the Runtime to terminate it in an unusual way'  When I try to update the module in Pycharm, I get an error 'gdal version is not defined'


OpenOffice Writer: preserve hyphen in text

I often use an editor like OpenOffice Writer to build documentation. My documentation is usually technical, and it often includes commands for the terminal.  When I format a command, I will indent the command by 1/2 inch and I will change the font to Times Roman or Times New Roman.  The editors replace a hyphen with a dash (I think its called an em-dash). So a command like:  ls -al   will fail when copy/pasted into a terminal due to the errant character.  The problem comes to light after performing a "Save as PDF". No matter what I do, the PDF always ends up with the wrong dash or hyphen (even if the OO document seems correct).  How do I distinguish text that include a hyphen so that the dash is unchanged?


how would you prove that $2\sqrt5 +\sqrt{11}$ is irrational? I started with a proof by contradiction that assumes that $2\sqrt5 +\sqrt{11}$ is rational and therefore there exist integers $a$ and $b$ such that $\frac{a}{b}=2\sqrt5 +\sqrt{11}$ and squaring both sides yields $\frac{a^2}{b^2}=31 +4\sqrt5\sqrt{11}$ and from this point im stuck as i dont know how to continue to arrive at a contradiction.


Hamburger menu should be placed right or left in website?

I met a client yesterday and he asked me a question I.e. weather hamburger menu should be placed on the right side or left side of the page. My answer was to place it on the right side because logically right side is the easy access to any user using mouse or track pad but his was counter was obvious that, why are everyone following left navigation (Amazon.com, fb.com). I was answer less for a minute. I know all the theory says left or maybe it's been a practice ever since hamburger menu was introduced. I'm finding hard to accept left side placement though I've used left side in many of the projects.  Please help me understanding this.


Relationship between reset pins and SWD functions (ARM Cortex M0)

On many microcontrollers or other devices without JTAG/SWD functionality, there is a reset pin which when low unconditionally and asynchronously forces everything into a known state.  On devices with JTAG or SWD functionality, however, things seem to be more complicated since it's possible to perform some JTAG/SWD functions while the reset pin is asserted.  I have some Freescale KL15Z-based boards which include the SWD pins on a connector with the reset line and some other diagnostic I/O pins.  Occasionally when connecting or disconnecting a cable, the parts seem to get into a weird state such that even reset won't kick them out.  I'm wondering if some stray pulses on the SWD pins might be putting the device into an "ignore the reset pin" state.  I have found that when using the debugger, I seem to have frequent difficulties getting the devices to reset reliably; I don't know if the issues may be related.  What is the relationship between the reset pin and the SWD functionality?  Conceptually it would seem most helpful to have a design where any falling edge on reset would be guaranteed to actually reset everything, and SWD communications which were supposed to happen before user code startup could be performed with reset held low, but I don't think that's how the Freescale KL15Z chips actually work.  What's the best way to solve such reset-related problems with the Freescale or similar parts?


When do we pronounce Z as "zed" and not "zi:"

When we learned the ABC song and English alphabet, we pronounced Z as [zed]. But in the practical usage, I never heard people say [zed], but they always say [zi:]  So when shall we say [zed]?  Or such pronunciation is totally archaic and not used in the modern English.


assign string to variable with if else condition

I have written the code. to check the variable value if it GL then SQLGL should XDOAPPL, if AP then SQLAP should assign XDOAPPL variable. but it is giving me the error.  APPL=$1 x=AP y=GL echo "Value of x = $x and y = $y." a=SQLAP b=SQLGL  if [["$APPL" = "AP"]}; then XDOAPPL=${a} echo "AP XDOAPPL =$XDOAPPL" elif [["$APPL" = "GL"]]; then XDOAPPL=${b} echo "GL XDOAPPL =$XDOAPPL" else echo "Nothing to go" fi


Among any $9$ real numbers, two satisfy $0 < \frac{x-y}{1+xy} < \sqrt{2} - 1$

Prove that among any nine given real numbers there are two numbers $a, b$ with the property: $$0 < \dfrac{x-y}{1+xy} < \sqrt{2} - 1$$  The fraction looks like $\tan(a-b)$, but I don't see if it can help. I don't have any other idea, I'm stuck. I also tried by reducing to absurd, but I didn't reach far. Could someone give me a clue?


Custom Permission is not recognized by Visualforce in the Tesing Org

I have a custom permission in my Managed Package. I use it in my Visualforce page to allow certain features for users that have this permission.  <apex:commandButton value="Register Connection"   action="{! registerAppConnection }"   disabled="{! NOT($Permission.Manage_App_Connection) }"/>   But when I open the Visualforce page in my testing org, where I installed the package, I see the following error:     Field Manage_App_Connection does not exist. Check spelling Error is in   expression '{!NOT($Permission.Manage_App_Connection)}' in component    in page mynamespace:settings   I checked the CustomPermission object and verified that this permission exists.  However, it works well in my dev org. I cannot figure out what is wrong.  Update  CustomPermission.obj    SetupEntityAccess.obj    As you can see it's in my testing org and names are correct. Why my visualforce page doesn't recognize $Permission.Manage_App_Connection is still a mystery to me.


Enter key don't responds when I'm trying to push var into an array

When I'm trying to push new name in to my array, enter key don't respond and there for I can't add another names.  Part of the JS:  $("input[type='text']").keypress(function(event){  if(event.which === 13){   var newName = $(this).val();    $("#" + "newName").append("#" + names);    names.push(this.value);    } });   My


How can I horizontally center a
 within another
 using CSS?

Foo foo


How to bring back drum roll sound in Ubuntu 17.10 when system is ready for user to log in

In Ubuntu 16.04, when I powered on my computer, the drum roll sound would be played right before I was presented with the Login interface. After I upgraded to Ubuntu 17.10 the drum roll sound is no longer being played. I did some research on the web and tried the following, which enabled the drum roll sound to be played, but only after I had logged in.  I launched Startup Applications Preferences and added an item that contained the following.  /usr/bin/canberra-gtk-play --id="desktop-login" -f /usr/share/sounds/ubuntu/stereo/system-ready.ogg   But this only enabled the sound to be played after I had already logged in.  I also tried  /usr/bin/canberra-gtk-play --id="system-ready" -f /usr/share/sounds/ubuntu/stereo/system-ready.ogg   But that had the same effect as the other attempt; the drum roll sound played only after I had logged in.  So I am asking whether anyone has found a way to enable the drum roll sound to play before the user has logged in, when the user is presented with the login dialog.  I also tried --id="system-bootup" which should have brought up the drum roll sound much earlier.  But even with that setting, the drum roll sound was not played until after I logged in.


What's the time complexity of doubling 1 until N?

def function(N):     foo = 1     while foo < N:          foo *= 2     return foo  I think it's O(log N), since foo is being multiplied by a constant amount?


I tried to put null rows and do many another things. I can't test this catch. It writes System.QueryException: List has no rows for assignment to SObject.  public List<MyObject__c> getList(){     try{         myList = [SELECT Id, Name, Title__c FROM MyObject__c];     } catch(QueryException e){         ApexPages.addmessage(new ApexPages.message(ApexPages.severity.ERROR, 'Query error:  ' + e.getMessage()));       }     return myList; }


What are extension methods in .NET?    EDIT: I have posted a follow up question at


If I turn an artifact into any creature for that turn that has an enter the battlefield effect, such as Vizier of the Scorpion, do I amass one? what if the artifact entered the battlefield that turn?


Why does every injured person in Game of Thrones refuse Milk of the Poppy?

I noticed Milk of the Poppy is offered every time some is near death.  Most people refuse it.  Is it refused because it will make you fall asleep and die?


node.js conflicts: /sbin/node vs /usr/bin/node

I have two Ubuntu 12.10 machines: machine A is a VMWare VM and machine B is and old Acer laptop. On both machines, I installed node using apt-get. However machine A installs the main binary as /usr/bin/node and machine B as /usr/bin/nodejs. Here are some behaviors I observed:   Both machine returns /usr/bin/node in response to the which node command. However, there is no such file on machine B. Issuing the command node works for machine A, not B. On B, I have to use nodejs instead. On B, there is a binary called /sbin/node, A does not have it.   These behaviors causes inconsistency problem when developing on both machines. For now, I worked around by renaming the binaries on B as such:  sudo mv /sbin/node /sbin/node-sbin sudo ln -s /usr/bin/nodejs /usr/bin/node   Is there a way to really fix this, so that node will be installed as /usr/bin/node instead of /usr/bin/nodejs?


I have two functions of very similar construction. The first creates a 3D list of dicts and adds data (the data consisting of the values of the three iterators used to construct the list). The second simply displays the dict data. The issue is that data displayed by the second function is wrong. Instead of showing values of the iterators increasing as expected: (0, 9, 19) (0, 9, 20) (0, 10, 0) (0, 10, 1) (0, 10, 2)  I end up with the maximum value of the iterators being displayed: (0, 12, 20) (0, 12, 20) (0, 12, 20) (0, 12, 20) (0, 12, 20)  Code as follows: xCount = 13 yCount = 21 numPages = 1 skip = [[4, 7], [4, 13], [8, 7], [8, 13]]  def createFrames():   frameData = {'textFrameName': ''}   framesData = [[[frameData for y in range(yCount)] for x in range(xCount)] for p in range(numPages)]    for p in range(numPages):     for x in range(xCount):       for y in range(yCount):          skipFrame = False          for entry in skip:           if entry[0] == x and entry[1] == y:             skipFrame = True          if skipFrame == False:           framesData[p][x][y]['textFrameName'] = str(p) + ', ' + str(x) + ', ' + str(y)           print(framesData[p][x][y]['textFrameName']) # shows p, x, y incrementing    return framesData  def displayData(framesData):   for p in range(numPages):     for x in range(xCount):       for y in range(yCount):          skipFrame = False          for entry in skip:           if entry[0] == x and entry[1] == y:             skipFrame = True          if skipFrame == False:           print(framesData[p][x][y]['textFrameName']) # shows 0, 12, 20 only   # Create text frames. framesData = createFrames()  # Add data to dictionaries. displayData(framesData)  Using python 2.7.16.


Find all multiplicative continuous functions on $(0,\infty)$

If $x>0,y>0$ and if $f(xy)=f(x)f(y)$, then $f=\, ?$   I tried the problem. And got it as $f(x)^n=f(x^n)$. But answer is $f(x)=x^n$. How? $f$ is a continuous function.


I'd like to buy a WQHD monitor which would serve as an external monitor for my laptop. I have HP DV6 series laptop:  and i as far i can tell monitor would need to be connected with at least HDMI 1.3 cable to be able to run at 2560x1440 resolution. My only concern is if my laptop supports all versions of HDMI.   Is there any way to check if my laptop can run with external monitor at 2560x1440 without actually buy it first?  Thanks for your help in advance


How to control your iPad with your Mac remotely?

I would like to know, is there a way to control your iPad with your Mac remotely (be able to see and manipulate iPad's desktop on your Mac)? I know that with the TeamViewer or other programs you can control your Mac with your iPad but not vice versa.


Shell pattern matching vs. regular expressions occurence

I am relatively new to Unix, and I stumbled across one curiosity. Some shell constructs like case or find, employ pattern matching, but it is not quite regex. Other commands, like  ed, sed, vi, and awk use regular expressions for pattern matching. Could somebody list which shell commands (builtins, programs) use regex, and which use the other type of pattern matching?


Is it possible to scale-out with Microsoft SQL Server?

Is it possible to scale-out a SQL Server database?  There are some solutions for , but is there a solution for load balancing and horizontal partitioning on SQL Server?  There are some in , but not in a standalone SQL Server instance...


Error: j_id0:j_id1:j_id28:j_id30: Validation Error: Value is required

I am getting above ugly error.How to clean the error without custom error handing in controller.  <apex:page standardController="Account" extensions="EventController">  <apex:form > <apex:pageMessages></apex:pageMessages> <apex:pageBlock > <p> Please select  </p> <apex:selectRadio value="{!selectType}" required="true">  <apex:selectOptions value="{!Option}"/> </apex:selectRadio> <apex:commandButton value="Next" action="{!next}"/> </apex:pageBlock> </apex:form> </apex:page>


Windows DNS clients can't update PTR records, but can update A records (not ACLs)

I have clients configured via GPO with the following settings enabled:   Dynamic Update Primary DNS Suffix Register DNS records with connection-specific DNS suffix Register PTR Records: Register   I also have two DHCP servers that are servicing the clients performing updates to the DNS records using a configured user (which is part of the DNSUpdateProxy security group).  The following is currently occurring:  1) A records are updated by clients.  ACLs look fine (the clients' computer objects have write access to their own records).  2) PTR records appear to be updated once by the configured DNSUpdateProxy user on the DHCP server(s).  ACLs look fine (the clients' computer object has write access).  3) Client machines don't appear to be trying to update the PTR records (although I've not pcaped anything yet); I say this because there are no errors logged by Dnsapi after ipconfig /registerdns.  So, what is going on here?  If I enable scavenging, the PTR records will be deleted as their timestamps are all from way back when they were originally registered.


I have three Macs I want to upgrade to Mavericks.  Is there a way of re-using the install files, so I don't have to do three separate 5gb downloads?


I am very interested in studying modules, which I have studied algebra, is basic theory of groups and rings, of Hungerford and Dummit. I was reading the Dummit the module, but I still struggled a bit in the section and the tensor product of exact sequences, as in the book of Atiyah. They know a simple book to begin with?


Proof of clockwise towers of Hanoi variant recursive solution

This is from one of the exercises in "", and is something I'm doing privately, not homework.  This is a variant on the classic towers of Hanoi, where all moves must be made clockwise only. The recursive solution is to consider $Q_n$ to be the number of moves to move a tower size $n$ one step across (e.g. from start $\rightarrow$ end post), and $R_n$ to be the number of moves to move it two (e.g start $\rightarrow$ end $\rightarrow$ spare).  The recursive solution is (sorry about the formatting, just getting to grips with tex):  $Q_n = 0 \quad \text{if n = 0}$  $Q_n = 2R_{n-1} + 1\quad \text{if n > 0}$  $R_n = 0 \quad \text{if n = 0}$  $R_n = Q_n + Q_{n-1} + 1 \quad \text{if n > 0}$  How can I prove these? I presume an inductive proof is required but everything I've tried to do just gets garbled into a mess of further decreasing $n$ values.  Explaining why these work is simple enough: $Q_n$ can be explained by the fact that you need to move a stack of size $n-1$ two steps forward followed by the $n$ piece, followed by moving the $n-1$ stack two steps again onto the $n$ piece=> $Q_n = R_{n-1} + 1 + R_{n-1} = 2R_{n-1}+1$.   The wordy proof for $R_n$ is similar: It consists of moving $R_{n-1}$ then 1 followed by $Q_n$, 1 and $R_{n-1}$ which will end us up with   $R_n = 2R_{n-1}+1+Q_{n-1}+1 = Q_n+Q_{n-1}+1$  But these are all just words that don't form any real proof... I've gone over the leading chapter and looked up some resources on proof by induction, but doing it with a recursion with two components has put me for a spin (having forgotten a lot of the math studied in the past certainly isn't helping either). If someone could run me through a rigorous proof for $n > 0$ it would be much appreciated.  As an aside, any recommended learning resources on proof by induction would be appreciated as I'm still barely "getting it".


How to prove Mandelbrot set is simply connected?

In this  of Harvard, it is proved that Mandelbrot set is connected, a result due to Douady and Hubbard. However, I lack necessary knowledge to comprehend it. Then in the same note it is said that the simply connectedness of Mandelbrot set is easier to prove.  However, I cannot find a proof through google. Can anyone provide me a reference or a proof of the simply connected of Mandelbrot set?


Work done by frictional force when rolling without slipping

When an object is rolling (no slipping) on a slope there should be a frictional force  which causes rotation. But when we use power insulation philosophy, we haven't considered about an energy loss against frictional force. So I have a doubt that when the object is rolling without slipping is there any connection between work done by force of friction and rotational kinematic energy?


LWC Showing Related fields in Lighting Datatable

Is it possible to display related fields in a lightning-datatable in LWC?  For example, I want to show the recordtype name.  I am querying RecordType.Name in the Apex.  When I set the columns in my javascript I just enter the name the same way but it does not display in the table.  Here is the javascript for creating the columns: const columns = [ {label: 'Record Type Name', fieldName: 'RecordType.name'}, {label: 'Line_of_business', fieldName: 'Horizon_Product__r.Line_of_business__c'}, {label: 'Name', fieldName: 'Name'}  ]; Thank you!!!


Show that one point compactification of $\Bbb Q$ is not Hausdorff .   Suppose to the contrary $\Bbb Q$ is Hausdorff, then we take two points $x,\infty\in\Bbb Q$, $x\ne\infty$, and produce disjoint open sets $U,V$ such that $x\in U$ and $\infty\in V$. By definition, we know that $\Bbb Q\setminus V$ is a closed and compact space such that $x\in U\subseteq\Bbb Q\setminus V$.  Please help me to complete the proof.


Software Center Not Showing Installed Apps

Just upgraded to 20.04. At first the software center was working fine. I could scroll down and look at the categories. I could click on the installed tab and see the installed apps. A few hours after later the installed tab is just blank. Today, I can't scroll down to the categories. Is this just a bug that will get fixed soon or should I reinstall it? If so, how do I reinstall it?


Potential issues (if any) in recursively replacing spaces with underscores across all filenames on hard-drive

In my external hard drive, there are about 1TB of data (PDFs, plain text docs, pictures, binary execuatables etc.). The data was created in Windows 10 and the hard-drive is formatted NTFS.  Starting from the root of the hard drive, I would like to recursively descend into each folder and replace the spaces in all files with underscore to make it easier to work with them from the terminal.  I saw the question : and thinking of using the top answer there   rename 'y/ /_/' *    from the root of my external hard drive.  However, that thread does not have a high view count and only 2 members have upvoted the answers. Being a novice, I am a little concerned if there might be any inherent issues in this. Is there a better way to handle this issue of cross-platform ease of working at the terminal ? (maybe advice like 'do this only for plain text files, or some other problems that I am not able to foresee')


How to identify Required fields via the API

When you create a field in Salesforce you can make it Required at the object level:  These required fields then cannot have FLS set via the profile. If you try and set FLS for them via the metadata API you get an error. So it would be useful to be able to work out which fields are marked as 'Required'. So how do you do that? There isn't any obvious field for it in the API or the Metadata API. The  has a 'nillable' property fields but that is also set for all checkboxes, so that can't be it.


How to prove that $z\gcd(a,b)=\gcd(za,zb)$

I need to prove that $z\gcd(a,b)=\gcd(za,zb)$.    I tried a lot, for example, looking at set of common divisors of the two sides, but I can't conclude anything from that. Can you please give me some advice how I can handle this problem? And $a,b,z \in \mathbb{Z}$.


Understanding the "process substitution" concept

I seek a simple explanation about the term "process substitution" aimed for general audience / non professional sysadmins, which do server environment maintenance for personal projects once in a while and not daily for customers or companies, if its okay to ask for it here.  What problem/s this concept was invented to solve What process is being substituted and with what (the name might mislead)? Is it also named "preserving stdin" and if so why? If the stdin device holds standard input which can be piped to another command, what is there to "preserve" further than that?  This might help me to understand the following command: bash <(wget -O - URL)  Note for newcomers: -O - tells wget to write data to stdout;


How to understand "with" in the following sentence?

Not every job will end up with a success.   What is the meaning of "with" here? Why not use other preposition?  Could native speakers please describe the scene of this sentence for me? Thx.


How to return a null/default value when using generics that support objects/structs?

I'm doing some dynamic A.I. programming and to avoid having to create so many different classes for each use case, so that the parameters can be passed correctly, I thought I'd use an an object bag/container, akin to a dictionary.  In order to support it fully generic, I made the key a Type parameter so I can use it in other projects, which works fine. My issue is, I want to support objects and structs so when it comes to implementing a TryGet style function, I don't know how to assign the out parameter.  Here is my class:  using System; using System.Collections.Generic;  namespace mGuv.Collections {     public class ObjectBag<TKey>     {         private Dictionary<Type, Dictionary<TKey, object>> _objects = new Dictionary<Type, Dictionary<TKey, object>>();          public ObjectBag()         {         }          private bool HasTypeContainer<T>()         {             return _objects.ContainsKey(typeof(T));         }          public bool HasKey<T>(TKey key)         {             if (HasTypeContainer<T>())             {                 return _objects[typeof(T)].ContainsKey(key);             }              return false;         }          public void Add<TIn>(TKey key, TIn value)         {             if(!HasTypeContainer<TIn>())             {                 _objects.Add(typeof(TIn), new Dictionary<TKey, object>());             }              _objects[typeof(TIn)].Add(key, value);         }          public bool TryGet<TOut>(TKey key, out TOut value)         {             if (HasKey<TOut>(key))             {                 value = (TOut)_objects[typeof(TOut)][key];                 return true;             }              // As expected, I can't assign value to null             value = null;               // I also can't just return false as value hasn't been assigned             return false;         }     } }   Is there anyway to assign value to the default of anything that is passed in?  I.e. I want to be able to do:  ObjectBag<string> myBag = new ObjectBag(); myBag.Add<int>("testInt", 123); myBag.Add<TestClass>("testClass", new TestClass(); myBag.TryGet<int>("testInt", out someInt); myBad.TryGet<TestClass>("testClass", out someTestClass);   I don't want to use ref, as that requires initializing the variable before passing it in.


need help on a error called StackOverflowException: The requested operation caused a stack overflow

i am try to make a mini password game to learn c# on a course and i keep getting this error when im try to make the game read the password. here is the code anything i need to get rid of? or maybe add? if this helps im using unity as my engine. thanks // Game state int level; enum Screen { MainMenu, Password, Win };  Screen currentScreen;  string password; // Use this for initialization void Start() {     ShowMainMenu(); }  void ShowMainMenu() {     currentScreen = Screen.MainMenu;     Terminal.ClearScreen();     Terminal.WriteLine("What would you like to hack into?");     Terminal.WriteLine("Press 1 for the local library");     Terminal.WriteLine("Press 2 for the police station");     Terminal.WriteLine("Enter your selection:"); } void OnUserInput(string input) {     if (input == "menu")     {         ShowMainMenu();     }     else if (currentScreen == Screen.MainMenu)     {         Runmainmenu(input);     }     else if (currentScreen == Screen.Password)     {         Checkpassword(input);      } }    void CheckPassword(string input) {     if (input == password)     {         checkpassword(input);         Terminal.WriteLine("Sorry, wrong password!");     }     else     {         Terminal.WriteLine("WELL DONE!");       }   }  private void checkpassword(string input) {     Checkpassword(input); }  private void Runmainmenu(string input) {     {         if (input == "1")         {             level = 1;             password = "book";             StartGame();         }         if (input == "2")         {             level = 2;             password = "handcuffs";             StartGame();         }         else if (input == "007")         {             Terminal.WriteLine("Please select a level Mr Bond!");         }         else         {                      }     } }      void StartGame() {     currentScreen = Screen.Password;     Terminal.WriteLine("You have chosen level " + level);     Terminal.WriteLine("Please enter your password: "); }  void Checkpassword(string input) {     checkpassword(input);  }  private void runmainmenu(string input) {     runmainmenu(input);       }  string GetDebuggerDisplay() {     return ToString(); }


Energy of Electromagnetic Radiations is given by e=hc/λ. Implying shorter the wavelength more the energy. Cooking food requires energy. So why we cannot use Cosmic Rays with wavelength of about 0.01 angstrom in microwaves (though they will be cosmic waves oven)? Why we use the Spectrum of higher wavelength?


On an exercise from Royden&Fitzpatrick's Real Analysis Book

Exercise 47 in Section 2.7 of Royden&Fitzpatrick's Real Analysis Book says that "a continuous strictly increasing function that is defined on an interval maps Borel sets to Borel sets".  But here do we need the continuity condition really? Because it seems that, without any continuity condition, the result follows directly from two preceding exercises, one of which says that "a strictly increasing function that is defined on an interval has a continuous inverse", and the other asserts that "if $f$ is a continuous function and $B$ is a Borel set, then $f^{-1}(B)$ is a Borel set".  I think that the continuity condition is superfluous. Am I right? Or, is there a detail which I cannot see? Thanks in advance for any comment.  EDIT: Here I just wanted to know that if the aforementioned exercise in Royden&Fitzpatrick's Real Analysis Book can be stated as "a strictly increasing function that is defined on an interval maps Borel sets to Borel sets". And I see that the answer is "yes". Thanks for the link.


What is the point of the Red Thread/Tape around evidence or newspaper clippings?

I have seen in a lot-lot of movies that the person who searches for a crime or another person creates a web of red tape or wire around the newspapers and evidence he acquires. I never guessed its usefulness and am therefore asking why do they do it?  Here is an illustration I created:


Is there anyway to have various levels for php enumerations?

Does anyone know for php AbstractEnumeration if there is any way to do another level underneath it?   so like...  const a = 'a'; const b = 'b';   But I have an optional parameter for a:  const a = 'a' => '=123'   I know this is probably going to end up as a hash table instead, but just wondering what interesting things I can do with php enums.


java Date object- how to increment day of week

I am currently trying to schedule a method for execution once per week on a day which the user will select. I know I can get the current date via:  Date date = new Date();   When setting up my TimerTask for execution, I need to increment the date by 1-6 days depending on which day of week is selected by the user. I do not see a setDay() method in the documentation and was wondering if parsing the day out, changing it, and adding back to the date object is the only way. Seems like something much more simple would be out there.


How do you sign into the Game Center in Pewdiepies tuber simulator

I recently had a glitch with the game so I had to delete it. When I got it back, it made me start all over and I can't sign into my old account that was on my Game Center. Is it possible to log in to my old account or do I have to start over?


Multivariate Hypergeometric Distribution with "or more" Successes

I understand how to calculate multivariate hypergeometric distributions.  For example, if you have an urn with 2 red marbles, 4 white marbles, 8 blue marbles, and 12 orange marbles, the probability of drawing 5 marbles and getting 1 red marble and 2 white marbles is as follows:  $P = \frac{{2 \choose 1}{4 \choose 2}{20 \choose 2}}{26 \choose 5}$  What I'm wondering is if I wanted to calculate 1 or more red marbles and 2 or more white marbles, if that could be calculated this way:  $P = \frac{{2 \choose 1}{4 \choose 2}{24 \choose 2}}{26 \choose 5}$  where I'm adding in the extra red and white marbles to the last combination. If this doesn't work (which I don't think it does because the numerator and denominator no longer match) why not, and is there a nice solution to this problem that doesn't involve summing all of the separate probabilities?


Assume $n$ and $r$ are nonnegative integers where $$0\le r\le n$$How can one simplify $$S=\binom{n}{0}-\binom{n}{1}+\binom{n}{2}-...+(-1)^r\binom{n}{r}$$ ?  I think that this combinatorial expression should be either solved using a combinatorial way but I don't know how. Probably It's also useful one tries to represent somehow using binomial representation of $(a+b)^n$.  I appreciate any idea given!


I need to use internet, but without being able to be called. So basically just block all incoming calls. I used to enable flight mode, but doing so, I'm not able to connect to the internet.  Is there an alternative?


Books similar to The Lord of the Rings: dark elves, different gods, Thommas, red-haired woman

This morning I was riding in the train when I heard two fellows discussing an upcoming movie. They likened it to The Lord of the Rings with orcs and elves and (I think) magicians etc. They also mentioned that it is a story that originally appears in books. I've been trying to figure out what books these are, because I am interested in potentially reading them.  Below are all the details I can recall:   There are elves, similar to the elves in The Lord of the Rings, but these are dark elves. (They mentioned they can reuse the elves from lord of the rings when making the movie and just color the hair black) Also, there was something of red elves that may or may not be included in the story Pretty sure there is magic related to the story in one form or another There was something about different gods (e.g. god of chaos, god of x, god of y, etc.) which may or may not still exist They mentioned the name Thommas a few times in a way that makes me think he is one of the main characters They mentioned something about some bloke (may or may not be the Thommas fellow mentioned above) being stuck somewhere eternally fighting something, or his body being stuck there or some similar plot They mentioned orcs, but I'm not sure whether or not this is included in the story or part of the discussion about Lord of the Rings   Like I said, I heard this from 2 blokes in the train, and I was not about to walk up to them and ask what story they are discussing. I hope I've gathered enough details for someone to help me identify the story.    Oh, I just recalled one last thing. There was something about a queen or some other important woman who is apparently a red head.


what to do for one who starts a faculty job before semester starts

What will be expected to do on a newly hired faculty member to start before a semester starts? No course to teach. Of course one can do their own research.  1.But is there any departmental need for the new hire to do during summer for example?   2.Will the school be willing to have new hires start 2 months before a semester starts?


"You can only post once every 40 minutes" on my first post

I have never posted on the  yet.  I just wrote my first question, but when I click "Post Your Question", I get "You can only post once every 40 minutes."  I haven't posted any question today on any Stack Exchange site.  I tried to report this on the , but I got the same issue.  Let's try here...


"to successfully complete" or "to complete successfully"?

A Google search yields 41,200,000 results for the former but only 3,150,000 for the latter.  Are split infinitives really to boldly be avoided in English grammar, or are millions of people just unaware of / uncaring for their existence?


Is there a good reference for UI terms in spanish? Terms like username, password, login/logout, etc... aren't direct translations.   I'm looking for a guideline to translate these labels.   Update I've started a running list of common UI terms with spanish translations.   Contribute:   View:


The character of portuguese can't print on php, what must i do?

i try to print this word,  echo "AUTO DETENÇÃO"   but the output is AUTO DETENÃ‡ÃƒO . This word is Portuguese.


What is the best casting method to use when casting int to uint32_t?  Should I use (uint32_t)num, or reinterpret_cast<uint32_t>(num), or static_cast<uint32_t>(num)? (Or something else)?  I know that there are many explanations out there regards the different casting types, but I want to ask specifically about primitive types.


How to solve simultaneous inequalities (reasked)?

I am doing multivariable calculus, and specifically double integrals. I am facing difficulties finding the domain of the integal, however i am given the following equations: $$1≤2x+y≤2$$ $$0≤x−2y≤1$$ Through these two equations i am supposed to find the area of integrals for each of the variables i.e $x$ and $y$ I set them as simultaneous inequalities but it doesn't seem to help because i get the boundary for xx to be $$2/5≤x≤1$$ and for $y$ to be $$4/5≤y≤0$$  which is obviously WRONG because how can the lowest boundary for the integral possibly have higher value than that in the higher.   please don't get me wrong, I am thankful to all the lovely & helpful people who tried to help (Henning Makholm, Shardulc, AlphaGo) and for the up-voting, its just i was new to this community and i thought they wanted my email to spam me, so i logged in as a guest.  Anyways, i just don't get how all these people arrived at their solution, is there a known way to solve such problems? Thank you all for everything.


How can I follow tags on Stack Overflow (so that the next time I log in, I can directly find my favorite questions from the main page)?


Will Stack Overflow's engine be (someday, or ever) open sourced?

Will Stack Overflow's engine become open source one day?  Warning: Some of the answers to this question no longer apply to the current situation. In the time since the question was asked  and came back as the  and  , for example.


How to use the batch to send more than 10 emails using callout. I've done a class batch that contains a start that has the query, an execute that has the sendEmail and a finish that has nothing but this is due to that does not work.  global Database.QueryLocator start(Database.BatchableContext BC) {          return   Database.getQueryLocator(query)}        global void execute(Database.BatchableContext BC, List<Contact> scope) {              SES sesEmail = new SES(as3.key,as3.secret);               for(sObject s: scope){                  sesEmail.sendEmail(subRecipients,sender,subject,newBody);          }    //update scope; }


I need to search a string in the string array. I dont want to use any for looping in it  string [] arr = {"One","Two","Three"};  string theString = "One"   I need to check whether theString variable is present in arr.


How many of the 230 crystallographic groups are realized in nature?

All of them or only a subset?   This is a famous and fundamental result in solid state physics.


Let's take a wire or a rope. I usually do this with a chain or my scarf.  I fixate one end in my hand and apply rotation (by subtle movements of this endpoint like spinning a lasso). The rope gets into rotation and obtains certain bent shape:   Some part is missing because cellphone cameras ain't great for high-speed photos but I hope you can imagine all the scarf.  The question is: how can I calculate/predict this shape?  Although this problem doesn't seem that bizarre, I have never seen any solution. Nor I have found this question asked anywhere on internet... Must be because I just don't know how to formulate it without pictures.  Also by taking longer rope I get more than one bend:   I apoligize for the quality again. It is even harder to rotate this while taking picture. The form is not spiral, it is more like a shape in a plane that's rotating.  I'll be thankful for explanations, solutions, links or at least a correct formulation of this problem.


Android compare string with two method but still not work

Can you help me, why my code not work?  Output :  03-17 16:54:25.488: D/wew(3821): msg :test  03-17 16:54:25.488: I/System.out(3821): #1: false  03-17 16:54:25.488: I/System.out(3821): #2: false  And this is my code :          charsRead = in.read(buffer);                         if (charsRead != 1) {                             String message = new String(buffer).substring(                                     0, charsRead).toString();                             Log.d("wew", "msg :" + message);                              String w1 = "test";                             String w2 = message;                              if(w1 == w2){                                 System.out.println("#1: true");                                 } else {                                 System.out.println("#1: false");                                 }                                  if(w1.equals(w2)){                                 System.out.println("#2: true");                                 } else {                                 System.out.println("#2: false");                                 }                          }


C# How correctly control checkbox from another thread?

I'm trying to uncheck checkbox after timer stops. But somehow I receive an error on OnTimedEvent method in this part checkBox1.Checked = false;:     Cross-thread operation not valid: Control 'checkBox1' accessed from a   thread other than the thread it was created on.   There is part of my code:  namespace WindowsFormsApplication1 {  public partial class Form1 : Form {     System.Timers.Timer timeris = new System.Timers.Timer();     int test = 0;      public Form1()     {          InitializeComponent();     }  private void checkBox1_CheckedChanged(object sender, EventArgs e) {     comboBox1.Enabled = (checkBox1.CheckState == CheckState.Checked);      if (comboBox1.Enabled)     {         button1.Enabled = false;     }     else     {         button1.Enabled = true;     } }  private void button1_Click(object sender, EventArgs e) {     if (comboBox1.Enabled)     {         if (comboBox1.SelectedIndex < 0)         {             comboBox1.Text = "Select from list";         }         else         {             this.Hide();             timeris.Elapsed += new ElapsedEventHandler(OnTimedEvent);             timeris.Interval = Convert.ToInt32(test);             timeris.Start();         }     }     else     {                     this.Close();     } }  private void OnTimedEvent(object sender, EventArgs e) {     timeris.Stop();     if (checkBox1.Checked == true)     {         checkBox1.Checked = false; // there I receive an error     }     this.Show(); } }   Have you any ideas how could I solve It? If I build application and launch .exe file It looks like working successfully, but I got an error while debugging.


How to loop through a CSV with multiple lines to grab 2 variables?

I have a CSV file that contains usernames and passwords. The file looks something like this: user1,password1 user2,password2 user3,password3  I need to loop through each line to grab the username and password, use those variables, and then grab the next set of usernames and passwords, replace the content of the variables with the new ones, etc. I've been searching for the best way to do this, but I'm not very familiar scripting and I'm getting lost. I've used awk to grab both individually, but I'm struggling to figure out how to use awk within a while loop. And I'm reading that might not be a great approach.


Teen Sci-Fi book probably from 80's possibly early 90's - aliens help a teenager on Earth

I can't remember much about the book.  I read it when I was in middle school.  What I do remember is that a human kid finds these tiny aliens - one of which can stop/slow time.  The one scene that sticks out in my memory is a bully trying to punch the kid, and the alien stops or slows down time enough that the kid has time to easily dodge the punch.  Honestly can't remember much more from the book.  Any help would be appreciated.


Software for recommending papers -- does this exist?

I spend a lot of time on google scholar making sure I haven't missed relevant literature. Usually this means scrolling through the "cited by" list one by one for at least 5-10 major papers on the topic. It occurs to me that this could be done better and faster by a computer. Has anyone made software that does something like the following? Input: A collection of papers Output: Some papers similar to the input papers, based on citations or semantic analysis I have in mind something like the "related papers" link on google scholar, but accepting more than one paper as input.


NullPointerException in group class. can't find an array object

so when i try to run my Group class, it tells me that the content of the student array is null and i cant find where specifically (been spending the last 4 hours trying to figured it out).if you have any questions regarding of classes, dont hesitate to ask.  thanks in advance for all of your answers.  Group class        public class Group {          private Student studentArray[];         private int nbOfStudent;          public Group() {             studentArray[]= new Student[24];         }          public void add( Student stud){             studentArray[nbOfStudent]=stud;             nbOfStudent++;         }          public String toString(){             String msg="";              for(int i=0;i<studentArray.length;i++){                 msg+=tabStudent[i]+" ";             }              return msg;         }          public Student getStudentArray(int i) {             return studentArray[i];         }          public Student[] getstudentArray(){             return studentArray;         }          public void setStudentArray[](Student[] studentArray) {             this.studentArray= studentArray;         }          public int getNbOfStudent() {             return nbOfStudent;         }          public void setNbOfStudent(int student) {             this.nbOfStudent = student;         }         public int search(String code){             return UtilsTabs.search(studentArray, code,this.nbOfStudent);         }          public void sort(){          UtilsTabs.sort(studentArray, nbOfStudent);         }     }   UtilsTabs class  public static void sort(Student[] array, int nbOfStud){     Student temp=null;     int minIndex=0;      for(int i=0;i<array.length-1;i++){         minIndex=i;          for(int j=i+1;j<nbOfStud;j++){             int  comparedValue = tab[j].compareTo(tab[minIndex]);             if( comparedValue< 0){                 minIndex=j;             }         }         temp=tab[i];         array[i]=array[minIndex];         array[minIndex]=temp;     } } public static int search(Student array[],String code,int nbofStud){      int pos=-1;      for(int i=0;i<tarray.length;i++){          if(tab[i].getCode().equalsIgnoreCase(code));               pos=i;     }      return pos; }   Student class  public class Student {     private String code;     private String name;     private Grades evaluation;       public Student(String code, String name, String eval) {         this.code = code;         this.nom = nom;         this.evaluation=new Grades(eval);     }     public Message message(){         if(this.evaluation.gradeAverage()<60)             return Message.FAILED;          else             return Message.SUCCESS;     }      public boolean equals(Student other){         boolean res=this.code.equals(other.code);         return res;      }      public int compareTo(Student other){         int res= this.code.compareTo(other.code);         return res;      }  }   test of class group  Group gr = new Group();  Student stud2 = new Student("26161234", "Marc", "65 81 58 100 79"); gr.add(stud2);  Student stud=new Student("24910003", "Pierre", "45 59 36 66"); gr.add(stud);  //show group of student System.out.println("Group of students:\n" + gr.toString());   this is what the console shows me


"..for being so thoughtless."- What is the tense/grammar behind this formation?

While reading a letter I found the sender wrote, "I hope you will forgive me for being so thoughtless.   If I rewrite it, should it look like,    "I hope you will forgive me because I was so thoughtless."  "I hope you will forgive me because what I did is wrong."   I was just wondering the part of the expression, for being so thoughtless; is that a present continuous tense! Not sure about the grammatical format.


Why is there no option to login as root?

Why does Ubuntu not allow the GUI users to login as root at the time of system start up like administrator in Windows?  Why they are restricting us to login only through the terminal?


I'm using Ubuntu Server 20.04 for Raspberry Pi 4, I'm trying to get a .sh file to run at boot, so I can just plug the Pi in and it runs the script, but how do I do that.


I want to install utorrent but unfortunately it is not available in software center. So please tell me how to do so using terminal.


I like music. I like the music.   I know the difference between the previous two sentences is that 'the music' is specifically talking about a music.  Is there any more difference in meaning? Can you tell me some cases where the definite article isn't required?


I'm trying to mount a RAM disk on startup with this:  /Users/Aram/Development/Tools/ramdisk.sh  diskutil erasevolume HFS+ "RamDisk" `hdiutil attach -nomount ram://800000`   com.aram.ramdisk.plist  <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"          "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0">     <dict>         <key>Label</key>         <string>com.aram.ramdisk</string>         <key>ProgramArguments</key>         <array>             <string>/bin/sh</string>             <string>/Users/Aram/Development/Tools/ramdisk.sh</string>         </array>         <key>RunAtLoad</key>         <true/>     </dict> </plist>   And then running:   sudo chown root:wheel /Library/LaunchDaemons/com.aram.ramdisk.plist sudo launchctl load -w /Library/LaunchDaemons/com.aram.ramdisk.plist   But I get these in the console:  1/08/12 1:29:25.982 PM fseventsd[64]: could not open <</Volumes/RamDisk/.fseventsd/fseventsd-uuid>> (No such file or directory) 1/08/12 1:29:25.982 PM fseventsd[64]: log dir: /Volumes/RamDisk/.fseventsd getting new uuid: 102D7293-F1F1-4640-AA50-D547C365339F  1/08/12 1:29:24.561 PM sudo[1193]:     Aram : TTY=ttys000 ; PWD=/Library/LaunchDaemons ; USER=root ; COMMAND=/bin/launchctl load -w /Library/LaunchDaemons/com.aram.ramdisk.plist  1/08/12 1:40:17.052 PM com.apple.launchd[1]: (com.aram.ramdisk) Throttling respawn: Will start in 8 seconds   It works if I set KeepAlive to true, but then it creates a RAM disk every 10 seconds.  Is there a way to delay the script for 10 seconds before running?


Can you save UV images automatically? (Along with when you save a file)?

So a lot of times I lost all my texture paint work, sometimes I forgot to save it, sometimes it mysteriously turns to a previous 'save'. Either way, it would be much easier if the textures would save automatically along with a 'overall' file saving... its kinda hard to keep track when you have multiple materials...  Maybe there's an addon?


Divisibility criteria for $7,11,13,17,19$

A number is divisible by $2$ if it ends in $0,2,4,6,8$. It is divisible by $3$ if sum of ciphers is divisible by $3$. It is divisible by $5$ if it ends $0$ or $5$. These are simple criteria for divisibility.  I am interested in simple criteria for divisibility by $7,11,13,17,19$.


I need packages, man.  I can't find them.  I can find 'source clones'.  Are those packages?  I'm not connect to the Internet in Linux, so I need to download the packages on my Windows system.  Where do I get the packages?  Where are the PACKAGES?!?!?!?!


Trying to random an integer between 15-20, inclusive.  Am I implementing this code correctly?      Random radiusChooser = new Random();     radius = radiusChooser.nextInt(21)-6;


Why won't Smart UV Project automatically unwrap a simple chair?

I created a very simple chair mesh and I would like to unwrap it so that I can map a texture. I would like to have Smart UV Project unwrap it automatically, but whether I do it that way or try manually, I am unable to unwrap the model.   Is there something I'm missing?    I tried a few guides, but I'm not sure where I'm going wrong.  My File:


Ubuntu 16.04 no desktop just background wallpaper

Basically, every time I boot Ubuntu, no desktop loads, I just see the wallpaper. I don't know if its something to do with my graphics card (Nvidia GTX 970)? Someone help.


Why do people use present tense when they are quoting someone?

I've heard and used this a lot but was wondering why and is it even correct.  When you are in a conversation with your mates and you are telling a story and when you try to quote someone, you say      "and he goes 'Oh, I run marathons, too'. "   Why do we use present tense there? Can it be      "and he went 'Oh, I run marathons, too'. "   Is it a grammatically correct English?


Do you use an apostrophe for a group or institution name?

Say, if you're going to create a writers' group called The Writers Land (just made it up), will you add an apostrophe like this, "The Writers' Land"? It looks odd to me, but perhaps that's just me? Same with other things like an institution name: Would you say Writers Association or Writers' Association (when you're creating it)? Do readers prefer one or the other?


Unable to suggest edits from the Android App

First of all, I'd like to say that the new roll out of the SE app for Android is great. Love the rich formatting and editing features. The problem I have been having is that every time I try to suggest edits to someone's questions, I am prompted "the user is not allowed to suggest edits" even though I am in the desktop/web versions of SE. Why is this? update: I was able to suggest edit on the title and/or tags of qurstions, just not the body. How come?


Using bare infinitive with verbs such as "see", "watch", etc.: Present tense or Past Tense?

I know using the bare infinitive after verbs such as hear, see, watch, etc. conveys  a different meaning from using the present participle (verb+ing):        I watched him climbing over the fence ( Climbing wasn't finished at the moment of speaking)   I watched him climb over the fence ( Climbing was finished at the moment of speaking)       I noticed the majority of the Grammar books use past tense to explain the aforementioned difference. Personally, I think that is quite rational because the bare infinitive implies a completed or finished occurrence. This means that event belongs to the past. However, I have a problem conceiving similar sentences in the present tense. For example:   .   The questions is:     If the bare infinitive implies a completed action, then why should we use the present tense to talk about that event? (the event is in the past).      We can say that:      An uneasy feeling came over me as I watched him walk towards the revolving doors     Added info 1  If you think my "climbing" examples are irrelevant, you can check Cambridge Advanced Grammar In Use, page 60, Unit 30, Section D or just check this     Added info 2  My question is from the logical point of view. I think the act of "seeing" is instantly. Therefore, it is not rational to say "see" a "completed process" but, "saw" a "completed process".


What should I say and why?  1) Why is not this tree long?  2) Why is this tree not long?  3) Why this tree is not long? (I almost exclude this possibility)