Unfortunately i did replace windows7 with ubuntu os . my hard drive is formatted please help me any one to recovery my files

I have a Toshiba satellite A-200 laptop with a Vista OS on it with 4 NTFS partitions  (C:) Vista  (D:) Entertainment  (E:) Work  (F:) Sources   and I wanted to start using Ubuntu instead. So I tried it first from the live CD and everything was OK and all the partitions were shown and working and so I decided to install Ubuntu to replace Vista on the (C:) drive. After I did that I can no longer find my folders and files on the (D:), (E:), (F:) partitions and the only file system that is shown is one 198 GB although my HDD is 320 GB.  I can't access the lost data on the remaining 120 GB which I hope is still there and not totally lost  I am now working from the live CD but I am unable to install testdisk. Can I recover the Vista partitions by the product recovery CD to get my laptop back to the factory settings? Can I recover the NTFS partitions using a recovery program for Windows or will that make the problem worse?   I need these data badly as I don't have a backup for them.


I had set up an AWS EC2 which is running Ubuntu. I want to run a Node.js server on it and use Dropbox to sync some files. I use ssh to access my EC2 like: ssh -i xxx.pem ubuntu@ec2-xx-xx-xx-xx.ap-northeast-1.compute.amazonaws.com  Then I set up Node.js and Dropbox. (I set up Dropbox with the guide: ) I run my Node.js with: node app.js &  And it works. I can access my website with the IP of AWS EC2. And I run Dropbox with: ~/.dropbox-dist/dropboxd &  It also works, and sync my files. But after I close the terminal, the website is not accessible anymore. And Dropbox also stop running. Is there any way to keep the processes running forever?

I'm working on a Linux machine through SSH (Putty). I need to leave a process running during the night, so I thought I could do that by starting the process in background (with an ampersand at the end of the command) and redirecting stdout to a file.  To my surprise, that doesn't work. As soon as I close the Putty window, the process is stopped.  How can I prevent that from happening??


Extract from HTML file:

              ...   ... where start is an exported method in the file start_run.js.  With no type="module" it works. After I include it I get "start is not defined".   I find that it is possible to do this in the .js file:  document.body.onload = function( param ){     start( 'box1' ); }   This then runs as expected on load. But then I find that I have no obvious way for the HTML file to call this function with a parameter of its choosing.   NB I've also tried putting this as an inline attempt:     ... but that gives the error "import declarations may only appear at top level of a module".  What might I do about this?   Edit  As I understand it from ClearPerformance's answer referenced in their comment, this may then be the way to pass a parameter out:     ... though I can imagine that's probably terrible global pollution practice.

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


I started to learn English by listening English news, from time to time I will come across some word that I have not learnt, with only pronunciation how can I get the spelling of the word?  When you learn Japanese, if you heard some Japanese word you don't know, by inputing the content you heard you can easily get the word. For example, assume DA is a Japanese word and its pronunciation is ABCD, by inputing ABCD you will get DA.

Are there online tools to look up words from their pronunciation? For example, when I hear /bεə/, I want it to tell me that there are words bear and bare that are pronounced /bεə/.


On factorizing the pde we get:  $$(∂_x − 4∂_t)(∂_x + ∂_t)u = 0.$$  If we let $w=u_x+u_t$ then $$w_x-4w_t=0$$ and so $w(x,t)=f(t+4x)$ and so  $$f(t+4x)= u_x+u_t.$$ What do I do after this step?

Solve $$u_{xx}-3u_{xt}-4u_{tt}=0$$ where $u(x,0)=x^2$ and $u_t(x,0)=e^x$.  My workings so far: I have factored the differential equation in the following way: $$(\delta_x-4\delta_t)(\delta_x+\delta_t)=0$$ where $\delta_x=\frac{\delta}{\delta x}$ etc. Now if we let $v$ be the solution to $(\delta_x+\delta_t)u$ then we have the following two equations: \begin{eqnarray*} (\delta_x+\delta_t)u=u_x+u_t=v\\ (\delta_x-4\delta_t)v=v_x-4v_t=0 \end{eqnarray*} Now for $v$ we simply find $$v=h(t+4x)$$ where $h$ is an arbitrary function of one variable. Now what remains is find $u$ such that $$u_x+u_t=h(t+4x)$$ I am stuck here, I thought about making a change of variables $\zeta=x+t$ and $\eta=x-t$ and thus using the product rule to show that $u_x=u_{\zeta}+u_{\eta}$ and $u_t=u_{\zeta}-u_{\eta}$ and thus $u_x+u_t=2u_{\zeta}$ and we need to solve $$u_{\zeta}=h(t+4x)$$ (I left out the factor 2 because $h$ is an arbitrary function). Do I simply integrate now and conclude $$u=f(\zeta)h(t+4x)+g(\eta)=f(x+t)h(t+4x)+g(x-t)$$ This seems wrong to me...  Some help would be greatly appreciated!


Which one should I use here?  IN June 2014  or   ON June 2014  Why? Thanks.

I’m often confused when I speak about times and dates. What is the rule for using on, in, and at in the following sentences?   I will do it ___ Tuesday. We married ___ March. He returned ___ the same day. Every day ___ the same time, I walk the dog.


One of the curses of 2-liter bottles is that when carbonated beverages are stored in them for long periods (i.e. days between drinks) at least the last liter ends up being flat. However, if after every pour the bottle itself is crushed such that the remaining volume of air above the liquid is as small as possible, and such that the structure of the bottle will prevent it from deforming back to its original shape (easily done by crushing the dome first and then working your way down), then the soda will stay nice and fizzy down to pretty much the bitter end, when it becomes impossible to crush the bottle any more but a significant air volume remains.   I know the answer has to do with vapor pressures and equilibrium, but when I try and articulate my thoughts to others their eyes glaze over. Can anyone come up with a broadly accessible, fairly pithy, and yet technically correct explanation?  I realize this is perhaps slightly more on the chemistry side of things than physics, but (1) there's no chemistry Stack Exchange site, and (2)  seemed reasonable precedence.


I have a weird problem. If I compile with LuaLaTex and microtype some of my line breaks are messed upped, but I don't get any warnings. XeLaTex with/without microtype or LuaLaTex without microtype are creating the document just right.  Example(I didn't want to post the real text, so I replaced some words)   LuaLatex & microtype LuaLatex XeLatTex & microtype XeLatTex   Example code  \documentclass[twoside,a4paper,ngerman]{scrbook}  \usepackage{fontspec} \usepackage[ngerman]{babel} \usepackage{microtype}    \newcommand{\cen}[1]{\rule{#1pt}{1ex}}  \begin{document}     \cen{11.77} \cen{33.79} \cen{20.367} \cen{9.13} \cen{23.148} \cen{52.06}      \cen{38.49}-\cen{38.64}-\cen{74.26} \cen{35.59}. \cen{15.66} \cen{23.15}      \cen{63.03914} \cen{17.03821} \cen{8.25} \cen{24.02} \cen{28.02} \cen{18.00}     \cen{27.9} \cen{18.8559} \cen{80.55} \cen{17.03} \cen{22.19566} \cen{27.07}     \cen{25.44} \cen{47.17} \cen{11.617} \cen{23.72} \cen{13.7} \cen{16.425}     \cen{66.9264} \cen{15.2643} \cen{38.7411} \cen{41.97136} \cen{17.52}     Ein\-pla\-ti\-nen\-rech\-ner \emph{Rasp\-berry Pi} benötigt als \cen{88.81546}     \cen{15.51} \cen{18.26} \cen{23.43} \cen{27.76} \cen{24.02} \cen{13.73}     \cen{33.78} \cen{66.92} \cen{58.18}   \end{document}   Question Why do I get this strange behavior? Is there any way to avoid this when using LuaLaTex and microtype for a document?

Please see the following screen shots.    As you can see there are two "overfull" hbox there. However, LaTeX does not produced any overfull box warning at all. I tried to produce a minimal working example but without exactly the same layout, and fonts, and line breaks, it cannot be reproduced. So sorry that I cannot include a MWE in this question. (edit: please find an MWE further down).  However I tried to diagnose the problem. Since LaTeX does not see these as overfull box, it could be protrusion problem I guess. I setup the Minion fonts with fontspec (LuaLaTeX) as following,  \setmainfont[ UprightFeatures    = {RawFeature = {protrusion = mnr}}, BoldFeatures       = {RawFeature = {protrusion = mnr}}, ItalicFeatures     = {RawFeature = {protrusion = mni}}, BoldItalicFeatures = {RawFeature = {protrusion = mni}}, RawFeature = {expansion  = default}, Ligatures = {Required, Common, Contextual, TeX}, Numbers = {OldStyle, Proportional}, SizeFeatures = {   {Size =      -8.41,  OpticalSize = 8},   {Size =  8.41-13.01, OpticalSize = 11},   {Size = 13.01-19.91, OpticalSize = 19},   {Size = 19.91-,      OpticalSize = 72}}, ]{Minion Pro}   Ignoring the other things (for example the SizeFeatures is used to work around the problem that fontspec/luaotfload cannot select the right optical sizes). The problems appeared to the line  ItalicFeatures = {RawFeature = {protrusion = mmi}},   Where protrusion is turned on before the fonts setup by \pdfprotrudechars2 and mni is the protrusion setting for Minion Pro Italic. I translated the setting in MinionPro package to be used with LuaLaTeX (as the official release of microtype do not support LuaTeX with opentype fonts loaded by fontspec yet). A portion of the Lua file that setup the protrusion can be found below,  fonts                    = fonts                    or { } fonts.protrusions        = fonts.protrusions        or { } fonts.protrusions.setups = fonts.protrusions.setups or { }  --omitted codes--  fonts.protrusions.setups["mni"] = { -- Minion Pro Italic        factor = 1, left = 1, right = 1,    -- omitted code--   [0x0067] = {-0.070, -0.070}, -- g   [0x0069] = { 0.000, -0.110}, -- i   [0x006A] = {-0.090, -0.150}, -- j   [0x0070] = {-0.040,  0.000}, -- p   [0x0072] = { 0.000,  0.080}, -- r   -- omitted -- }   I I change the protrusion factor of letter g and p, which are the breaking points in the picture above, then the problem solved.  Can anyone explain the problem? Is there something wrong with my fonts setup (the use RawFeatures) or the protrusion setup file (the codes omitted in the above code snipes are just setting for other letters, which I assume should be independent from each other)?  It seems that whenever a linebreak happens at a italic character and protrusion is activated for that character, then the problems always happen. This does not happen for roman fonts.  Edits: Further experiments showing that assigning positive values instead of negative values to the protrusion factors does not cause any problem for the italic fonts. I guess the problem is not with Italic font, but with the negative value of protrusion factors. The reason no such problem for roman fonts is that there are no negative values assigned for any roman characters. But some italic characters has negative protrusion values so that they don't reach out the boundary too much.  Latest Edit: Here's a minimal document that triggers the issue.  \documentclass[a4paper]{article} \usepackage{microtype} \usepackage{amsthm} \newtheorem{proposition}{Proposition} \usepackage{lipsum} \begin{document} \begin{proposition}   \lipsum \end{proposition} \end{document}   With lualatex (showcases the bug):  With pdflatex (perfectly fine):


Blender material button doesn't work for selected object.   As you can see, it worked on the first object, but wont work for the plane, either. Maybe I messed up at the first object"s material, cause I'm new and it just wants me to give up? I tried transparency to the first object and I assume that we wouldn't be able to see that without rendering, since it's not partially transparent in this view.  Thanks in advance.

I have added a sphere and I was able to add material and give it a color. Now when I add a second sphere (separate object), the material panel is just blank.


Let $R$ be a unital ring (not necessarily commutative) and $x,y\in R$ be non-invertible elements. Then is $xy$ non-invertible? And how about the case $xy=yx$?  (postsclipt)  : This page gives a counterexample of the case $xy\neq yx$.

Let $A$ be a unitary ring. The question is simply: can the product of two non invertible elements in $A$ be invertible?  I proved that the answer is negative if $A$ does not have zero divisors, because if you have $a,b$ non invertible elements in $A$ and $abx=xab=1$, then $a(bx)=1$ so $a$ is right invertible and if we put $d=bxa  \implies db=b(xab)=b1=b  \implies d=1$ (because obviously $b$ is not $0$), so $a$ is left invertible, as desired. If $A$ does have zero divisors, I don't see how to adapt the proof...  Thank you!


I'm translating a course manual but I'm struggling with something. The manual could be read by a man or a woman.  In my own language, he or she or it doesn't exist, so I'm not sure how to make my texts easier to read.     The student can meet his/her Inner Guide who opens his/her heart chakra.   The teacher guides his/her student so he/she can advance more in his/her life.   I'm going to open his/her chakra and so he/she can express his/her emotions easier.

Is there a pronoun I can use as a gender-neutral pronoun when referring back to a singular noun phrase?  Each student should save his questions until the end. Each student should save her questions until the end.


Assume $p$ is prime and $p\ge 3$.  Through experimentation, I can see that it's probably true. Using Wilson's theorem and Fermat's little theorem, it's equivalent to saying $2^2 4^2 6^2 \cdots (p-1)^2 = (-1)^{\frac{p+1}{2}}$ mod $p$, but I can't figure out any more than that.

I need to show that for prime numbers of the form $p=4n+1$, $x=(2n)!$ solves the congruence $x^2 \equiv-1\pmod p$. I then need to show this implies p isn't a gaussian prime.   I have started to solve this using Wilson's theorem that a number $z$ is prime iff $(z-1)!\equiv-1\pmod z$. Therefore the endpoint of my proof should be that $(p-1)!\equiv-1\pmod p$.  As $p$ is of the form $p=4n+1$, I only need to prove that $4n!$ is congruent to $-1$ modulo $p$.   Here is my working so far: Starting with the congruence $x^2 \equiv -1\pmod p$:    $$\eqalign{x^2 = -1\pmod p&\implies   x^2 + 1 = kp \implies (x-i)(x+i) = kp\cr &\implies ((2n)!-i)((2n!)+i))=kp \implies 4n!- 1 =kp\cr}$$   This is where I start to run out of any ideas that seem to get me anywhere. Any tips would be greatly appreciated!


How to put a period after a matrix (and not have it float in the air). For example, consider the following matrix:  \begin{bmatrix} 2 & 1 & 1 & 2 \end{bmatrix}.   You find the period floats in the middle of the line rather than sinking to the bottom. How to make it appear properly at the bottom.

How can I put a full stop at the bottom rather than at mid-line following the end of an aligned matrix expression such as $\begin{pmatrix} x\\ y \end{pmatrix}$?


I have a confusion regarding the number of phones i can carry with me . As the iphone is cheaper in usa compared to india i wish to carry many iphone's with me (what is the max limit) .  I also do not want to pay the import charges , let's suppose if i unpack the phone's and the earphone's from the box and carry it with me. will tell the officials that they are all mine will they allow me or not .  edit 1. - i dont plan to sell these phones , i'll give one to my wife and rest will be used by me as official phone , personal phone and backup phone  edit 2. - i know there are other question on this same topic but they dont answer what precisely i wanna know i.e. if i just keep all the phone without any packing and that too in seperate baggage (2 phones in 2 seperate luggage bags , 1 in my pocket and the last one in my hand bag ) will it still rightfully attract custom duty  .

My Aunt lives in Newyork (United States) she's Indian, she's been there more than a year. I just ordered her 2 iPhone 6 phones for me and my brother personal use. The main problem is that with 2 iPhone + her own personal 1 iPhone 5s she is using. Will the Customs officials in Airport clear that 2 new Sealed iPhone as duty free or she will be charged? Help me here. If she will be charged than how much PERCENTAGE EXCISE TAX shall she pay?


I went to upload some photos and videos onto my macbook air and was told there was not enough free space, so removed some things onto an external hard drive and emptied my trash. I now have over 30 gb free but I still get the warning saying my hard drive is nearly full. How can I fix this?

Every few days I get notices on my MacBook that it's running or run out of hard drive space. Curiously, restarting the computer will enable me to recover gigabytes of space (this past time, it was able to recover about 2.2GB). However, I can't identify anything in my personal activity that consumed that space.  It's possible that it's a rogue iTunes podcast or a huge software update that my Mac is automatically downloading - would either of these reclaim the space upon a restart?  One possibility that I can think of is that FileVault has some sort of disk leak, allocating but not freeing files. Does this make sense? Is there a tool that I can run to determine where this space is going? Assuming it is FileVault, should I try to disable it? What's the best way to turn of FileVault on a nearly full computer?


Let $G=A\times A$;  $A$  be cyclic group of order $p$ where  $p$ is a prime .How many automorphisms does $G$        have?  My thoughts:  If we  have a cyclic group $G$  of order $n$ then I know that in order for $\phi:G\to G$ be an auto we have that $\phi(x)=x^i;\gcd(i,n)=1$ are the only ones . But I could not follow for this group .Any help

Suppose I have $G = Z_{p^m} \times Z_{p^n}$ for $m, n$ distinct natural numbers and $p$ a prime. Is there a combinatorial way to determine the number of automorphisms of $G$?


so isDog is clearly a function, I tested it with typeof but when I run the program I get a 'TypeError: undefined is not a function at Array.filter.' Am I thinking about this wrong? btw, I do know var dogs = animals.filter( (animal) => animal.species === 'dog'); works but confused as to why I cannot assign that function to a var and call it.  var animals = [   { name: 'Fluffykins', species: 'rabbit' },   { name: 'Caro',       species: 'dog' },   { name: 'Hamilton',   species: 'dog' },   { name: 'Harold',     species: 'fish' },   { name: 'Ursula',     species: 'cat' },   { name: 'Jimmy',      species: 'fish' } ]  var dogs = animals.filter(isDog);  var isDog = function(animal) {   return animal.species === 'dog'; }

I've recently started maintaining someone else's JavaScript code. I'm fixing bugs, adding features and also trying to tidy up the code and make it more consistent.  The previous developer used two ways of declaring functions and I can't work out if there is a reason behind it or not.  The two ways are:  var functionOne = function() {     // Some code };     function functionTwo() {     // Some code }   What are the reasons for using these two different methods and what are the pros and cons of each? Is there anything that can be done with one method that can't be done with the other?


Show $\mathbb{R}^2 - \mathbb{Q}^2$ is connected.  Now, I feel like showing that this is path connected is pretty simple, but showing that it is connected? The definition the we learned in class of a space being connected is:  A space $X$ is connected if and only if for all continuous maps $\alpha \rightarrow {0,1}$ we have that $\alpha$ is not onto.  I think another equivalent definition of connectedness may be more appropriate for this problem.  Anyway, can somebody help me out with this problem? Thanks!

Prove that $\mathbb{R^2}\setminus\mathbb{Q}^2$ is connected.   First of all, I know this was     in this site.   However I'm looking for a proof that does not use path-connectedness (which I know, but this exercise is from a previous lecture), nor the knowledge that $\mathbb{R}^2\backslash E$, where $E$ is countable, is connected (it's the second part of the exercise).  I tried using disjoint open sets and separated sets, and also using the fact that they should also be the intersection of sets in $\mathbb{R}^2$ and $\mathbb{R}^2\setminus\mathbb{Q}^2$, but I hit a wall there.  I have the feeling I'm forgetting something very basic and obvious, or I may be overcomplicating things.


I tried to update the system (Ubuntu 12.04 LTS "precise") with the Update Manager.  It shows 2 important security updates for language-selector-common (0.79.4) and language-selector-gnome (0.79.4), but they can't be selected.  They should be, as any package in Update Manager and as I had done a lot of times.  I check in Synaptic and found the two packages marked with an ! symbol in gray; I don't know what it means.  The installed version is 0.79, for both packages.  I mark them for update, and Synaptic asks to mark for delete language-selector-gnome, ubuntu-desktop and ubuntu-standard.  I don't know if I should delete them or do something different.   If I try to update language-selector-gnome first, it asks to delete ubuntu-desktop. If I try to apply the changes, Synaptics shows a message saying that it can not update because it has language-selector-commons as an unsolvable dependency (it needs language-selector-common 0.79.4).   What should I do?  Leave it without updating?  If update, which would be the correct order in the process? ("first delete this package, then update the other, then reinstall a third" or something like that).  Is the bug in Update Manager, instead?  I guess it has something serious; I've checked the changes report in the un-checkable update and it shows:  "SECURITY UPDATE: possible privilege escalation via policykit UID lookup race. - dbus_backend/ls-dbus-backend: pass system-bus-name as a subject instead of pid so policykit can get the information from the system bus."  It is confirmed in the National Vulnerability Database (linked from CVE-2013-1066), it links also to a bug for the update (0.79.4), not for the package to be updated (0.79):    So even the update should be reviewed.  Thanks in advance.

Ubuntu 11.10 is installed, and I have updated my system via Ubuntu Software Centre, and after the update 3 updates remain in the list. But I am unable to select them, the tickboxes cannot be checked and Ubuntu Software Centre gives no error when I try to check.  Also, below it says "There is no update to be installed" and even though there seems to be updates Install Updates button is unclickable.  What should I do in order to install these updates?


I have a public emailing apex class I need to call that from onclick javascript button of a detail page. Can someone let me know , if I can do that? Please give me an example. I am not getting it.  I have a global webservice method that receives List of an Sobject record.   Apex webservice method  webservice static void sendMails(List<Form_Requests_abv__c> newrequests)     {         Set<Id> formIds = new Set<Id>();         for (Form_Requests_abv__c  fr : newrequests)          {               formIds.add(fr.id);         }          List<String> sendtoemail = new List<String>();                  List<ABV_Form_Request_abv__c>  Useremails= ABV_Form_Request_abv__c.getAll().values();         if(!Useremails.isEmpty()){            for(ABV_Form_Request_abv__c Useremail : Useremails)            {                if(String.isnotBlank(Useremail.Email_abv__c)){ ...............   How can I pass value there?  My javascript code  var leadIds = {!GETRECORDIDS($ObjectType.Form_Requests_abv__c)};  sforce.apex.execute("MailerUtils","sendMails",{newrequests: leadIds}); window.location.reload();

I have a javascript button on my product layout named "ListToEbay" and I have written a controller to invoke the EndItem()  service method of ebay api.  Below is the method:--  public void  removeItemFromEbayList() {   HttpRequest req = new HttpRequest();   Http http = new Http();   sEnvelopHandlerForEndingList='Request XML';   req.setBody(sEnvelopHandlerForEndingList); }   I want to execute this method directly on clicking that button, without going or opening a VisualForce Page. How can I accomplish that?


We have the following server resources :  16GB RAM Memory Intel Xeon E5-2650 v2 @ 2.60GHz (8 Core) 240GB SSD (RAID 10) 1 IP Address (2 extra) Unmetered Traffic / 1Gbit Port / 100Mbps guaranteed   We are using piece of javascript on around 30 websites untill now sends HTTP requests to PHP script located on our server to track the page loads and save the website information in our MySQL DB.  So the requests sometimes reach millions a day and the server becomes too slow, once I disable sending the requests to our server, everything works fine.  From the apache error log, I found the following error :  [core:notice] [pid 4918:tid 139902294153344] AH00094: Command line: '/usr/sbin/httpd' [mpm_worker:error] [pid 4918:tid 139902294153344] AH00287: server is within MinSpareThreads of MaxRequestWorkers, consider raising the MaxRequestWorkers setting [mpm_worker:error] [pid 4918:tid 139902294153344] AH00286: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting   Also :  [mpm_event:error] [pid 22565:tid 140163371042688] AH00485: scoreboard is full, not at MaxRequestWorkers   After digging into this issue, I found an article to set the optimal configuration for Apache httpd.conf for such issues :  StartServers 5 <IfModule prefork.c>     MinSpareServers 25     MaxSpareServers 50 </IfModule>  ServerLimit 256 MaxRequestWorkers 1000 MaxConnectionsPerChild 10000 KeepAlive On KeepAliveTimeout 100 MaxKeepAliveRequests Unlimited Timeout 300   Still getting the same, I was thinking that it might be issue with many transactions to db in the same time, so I stopped the storing to db part in the script and got the same issue.  Any suggestions regarding the above issue ?  Assume we have moved to cloud hosting with more resources, is it still fine to save such requests to db immediatly ? I was thinking of saving into file and dump it each 4 hours for ex.

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?


Prove that for each $\epsilon > 0$ it's possible to find such n, so $| \sin(n)- \frac 1 2| < \epsilon$.    Let's represent $n$ as $n = 2\pi k +x,\space\space x \in(-\pi,\pi),\space\space k \ge0,\space k \in \mathbb{N}$ Then we could say, rewrite original statement like that: $\exists x: x \in (\arcsin(\frac 1 2 -\epsilon),\arcsin(\frac 1 2 +\epsilon))$ But I'm not sure where to go from here. I'm really not experienced with such kind of proofs, so I would appreciate a suggestion. Purpose of solving this is pure self-educational for me, so I would like to receive a suggestion only, not the whole ready answer. Thank you.

We know that the sine function takes it values between $[-1,1]$. So is the set $$A = \{ \sin{n} \ : \ n \in \mathbb{N}\}$$ dense in $[-1,1]$. Generally, for showing the set is dense, one proceeds, by finding out what is $\overline{A}$ of this given set. And if $\overline{A} = [-1,1]$, we are through with the proof, but i having trouble here!  Similarly can one do this with cosine function also, that is proving $B= \{ \cos{n} \ : \ n \in \mathbb{N}\}$ being dense in $[-1,1]$


I am trying to test my program that makes use of broadcast UDP (not multicast!). In Linux, I can use the 127.255.255.255:64651 address and everything works beautifully, in other words, I send a packet to 127.255.255.255:64651 and multiple clients listening on that port get the packet. A real broadcast example!  Unfortunately on my OS/X machine (Mountain Lion) the same example does not work.  Is there any way I can get 127.255.255.255 to work on mac machines? Any other solution to get broadcast working on my mac machine without a network?  Note: It has to be broadcast, not multicast.

I am trying to use ifconfig to turn on broadcast on my loopback interface. It currently reads:  lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384   As you can see, no broadcast address! :( :( :(  I tried this on OS/X but it did not work and it did not give any error or feedback:  ifconfig lo0 broadcast 127.255.255.255   Any guru would know that?    I have one server that sends one packet. I have two clients running on the same machine as the server. I need them to pick up the packet WITHOUT having to force the server to send it twice.


I am about to finish reading 'Introduction to Electrodynamics' by David Griffiths. Throughout the textbook, Griffiths makes frequent references to current literature (mostly articles from American Journal of Physics). So, I concluded that even though the theory of electrodynamics has a well established foundation, there might be some interesting "side problems" which are still open, hence the question.

Is classical electromagnetism a dead research field?  Are there any phenomena within classical electromagnetism that we have no explanation for?


I'm attempting a manual upgrade of a Vagrant VM box (of the WordPress dev environment , which uses ) from 14.04 (14.04.5 LTS I think...) to 16.04.2 LTS.  This is the second time I've attempted this, I took a snapshot beforehand.  I used do-release-upgrade rather than the Debian method, and I didn't see any obvious errors/problems during it.  On completion it reboots and hangs, until it gets as far as this:  [...] usbcore: registered new interface driver usbhid usbhid: USB HID core driver random: nonblocking pool is initialized     The VM apparently doesn't have grub, so I downloaded an Ubuntu Live CD ISO image, configured VirtualBox to boot from that, and ran boot-repair.   Latest options I've tried:      I was then able to access Grub and boot into recovery mode. (Incidentally grub is giving me two sets of options, version 4.4 and an earlier v3.13, I'm using the most recent).    I tried updating grub and doing dpkg --configure -a, though I suspect there was nothing wrong with either and these made no difference, it still hangs in the same place.  What do I do now / what to look for?  Also, if I were to restore the 14.04 snapshot and upgrade again, is there anything I could do beforehand that would likely prevent this?  Software versions:  Vagrant 1.9.2 VirtualBox 5.1.10 Mac OS X 10.11.6 (El Capitan)  VirtualBox settings:   Linux Ubuntu (64-bit) 2 MB RAM, Chipset ICH9 Enable I/O APIC - on Enable EFI - off Hardware clock in UTC time - on    4 CPUs Enable PAE/NX - off  Acceleration: Paravirtualisation interface: legacy Enable nested paging - on  Storage: SATA controller type AHCI 2 ports (1 for HDD, 1 for optical)

I'm trying to boot Canonical's Azure 16.04 .vhd file in a VirtualBox VM and it hangs at "non blocking pool is initialized".  It works in Hyper-V, so it may only be a bug in virtual box (5.0.20).


In Java why pass in a parameter, the parameter in a method to get the right change, but after calling this method in the main method of the parameter is not changed?  My code:  public void RSort123(Student[] stu) {     int k = 0;     Student[] stu1 = new Student[this.len];     for (int i = 0; i < this.len; i++)         stu1[i] = new Student();     Clear(array);     for (int i = 0; i <= 100; i++) {         for (int j = 0; j < this.len; j++) {             if (stu[j].english == i) {                 array[i][k++] = j;              }         }         k = 0;     }// 分配      for (int i = 100, j = 0; i >= 0; i--) {         for (int l = 0; array[i][l] != -1; l++) {             stu1[j] = stu[array[i][l]];             j++;         }     }// 收集      stu = stu1;     System.out.println("---------------stu----------------");     for (int p = 0; p < len; p++)         stu[p].display();     System.out.println("---------------stu1---------------");     for (int p = 0; p < len; p++)         stu1[p].display();     System.out.println("---------------end----------------"); }   Code Part of the main code   //Call the method.  But not work, But in RSort123() method stu changed. Why? rs.RSort123(stu);             System.out.println("姓名\t语文\t数学\t英语\t总分"); for(int i=0; i<length; i++){     stu[i].display(); }

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


I have found a Delphi source code from the net that I am going to use but I see that there are comments like procedure sortList; // sorry for O(n^2) but a log(n) is impossible. gl. Not going to post the code here, but it sorts stuff in a TList with some for loops.  I have read Marco Cantu and Nick Hodges books but I have never seen the O(x) thing. I have googled it and I have seen that indicates how much a procedure is fast. Is it correct?  Does delphi support this feature as well? Sorry but I have seen a lot of maths and I haven't understood very well.

I'd prefer as little formal definition as possible and simple mathematics.


What’s the difference between all and all of?  When should one use of following all to make all of, and when should one drop the of and just use all all by itself?  For example, in this sentence:     How come I can understand spoken American English better than British English in all its variants?   Is an of required after the all, making it all of its variants instead?  Dunno why but my instincts tell me that I shouldn’t put the of in right there. But I am unaware of source of my instinct.

I've heard both of these before.        All the good people   All of the good people      Are they both correct?


On Stack Overflow, I got the following error message.    What? I have been helping users on Stack Overflow for two years. I have posted almost 500 answers and only 100 questions. I have gained 10k reputation for this. And now, when I am in the need of help, Stack Overflow will turn back to me?  I am working very hard using a technology which is new to me. All my questions are very well researched and have 1+ upvote. I think I know how to ask a good questions, after two years of hard work here.  Sorry, but I would expect more trust from the Stack Overflow side instead of treating me like someone who is abusing.    Argument: You cannot ask so many good questions in 24 hours.   Answer: this is speculative and regulative. Stack Overflow was always about judging posts quality. Why it is not consistent in this? Why don't you look at the quality of question the user is posting, instead of pre-judging how many good question can he post?    EDIT 2019: in retrospective, you can see those 5 questions (, , , , ) I asked that day (one got closed), they have 21 score total, which is on average 4.2 votes each. So it is possible to ask high amount of good quality questions, as opposed to the prejudices which argue for the limit ;-)

I get a message:     Sorry, you are only allowed to ask 50 questions in a 30 day period   Why is there a question limit? 50/month is just not enough :)


I have the array:  array_h = "'0x5a','0x20','0x29','0x1','0x1','0x59eb5e8e'"   I need to convert it to this:  array_i = [41, 15 ,41, 1, 1, 1508444575]   How can I do it in Python?

How do I convert a hex string to an int in Python?   I may have it as "0xffff" or just "ffff".


As far as I know, Steam (and pretty much every other application) is installed to the "/" partition.  If that's the case, why is such a small "/" partition recommended?  Couldn't one or two Steam games wipe out your "/" fairly easily?  It seems like a "/" partition of 20GB max is usually recommended.  Am I missing something, or if I plan on installing games and applications should I make a larger "/" partition?  EDIT:  I'm asking because I haven't actually seen anyone mention this before. The general recommendation is to have a seperate /boot, /, /home, and swap partition, and the general consensus is that a "/" partition doesn't need to be any bigger than 10GB - 20GB. It seems as though everyone recommends something like this:   /boot - 500MB   / - 10GB - 20GB  swap - same as RAM  /home - rest.   Maybe I'm weird, but looking at my Windows 7 install "Program Files accounts for nearly 700GB of disk usage, and everything else (including Windows 7) is barely 100GB.   Is that not normal?  It just seems more normal in my mind to have "/" and /home switched.

I've checked in the home folder but this is all I see.


I'm not sure how this site has done it, but  appears to be able to load questions from private beta websites through the V2 API.   to the list of questions on Puzzling.SE. I only found this because one of our private beta questions was indexed, and I was researching an answer. It was the first result (yay!), but on the other hand, it was exposed.  Is this intentional? If so, what is Column80?

I'm a committer for the .  It went to the private beta phase sometime in the last 12 hours, but yet to have been invited. When I visit  I get the standard "To log in, you must have commited to the Area 51 site proposal and received the invitation email." message.  However, when I navigate to the Pets site via the Android app, I'm able to view the site in it's entirety (questions, answers and comments). When I attempt to post, I get a message saying my user token isn't allowed to take action on this site.  Same behavior is observed when using the iOS app.


Just need to ask the community if they've come across this malware that operates in 2 parts(that I've seen):  Installs a program '.2.1.2.3' that makes the taskbar disappear except from the start button and closes the open window randomly:  This program can be seen in Control Panel with no description at all of who the author is, etc. and based off of the Temp folder. A new folder in Program Files: C:\Program Files(X86)\Common Files\Novaweb, which will have a directory structure very like Firefox and a program called update.exe that runs every time Windows starts, opens a window with a funny name that closes when you try to maximize it and tries to access a malicious website:    Funny thing is that there is no firefox.exe in this "Firefox" folder. I just ran all the malware scanners I know of (Quick Heal, Malwarebytes, RKill), removed the suspicious program from Control Panel and deleted the Novaweb folder. Anyone else come across this malware? What did you do? Anything I've missed?

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


I'm interfacing with an Access database and so have to use either of two connection strings (Jet or Ace) depending on my platform selection (i.e. x86 or x64). The code that I'm working on could be compiled with either platform so I need a way to detect the platform "bitness". I've been told I can use IntPtr but I'm not sure how.  Thanks.  Edits:  Just want to say, this is NOT a duplicate! In the suggested link, the OP is asking for the Operating system's bitness, not the process's. And they are talking about .NET 2.0. I haven't seen anything in 2.0 in like three years.

In a  2.0 C# application I use the following code to detect the operating system platform:  string os_platform = System.Environment.OSVersion.Platform.ToString();   This returns "Win32NT". The problem is that it returns "Win32NT" even when running on Windows Vista 64-bit.  Is there any other method to know the correct platform (32 or 64 bit)?  Note that it should also detect 64 bit when run as a 32 bit application on Windows 64 bit.


The new version of Chrome will auto disable extensions that are not from Chrome Web Store, and cannot enable it manually in the chrome://extensions page.  How to enable the extensions and disable the "auto-disable" mechanism?

Does anybody know how to re-enable your own extensions after they were disabled by the Chrome v35 update?  (Mostly greasemonkey scripts in my case, thus simple .js files previously drag-n-dropped in to the extension windows. )  When I started up Chrome today I got the warning that some non-ChromeWebStore extensions were disabled.  More info was giving on this :      Extensions disabled by Chrome      You're seeing this notification because one or more of your Chrome   extensions has been turned off to make Chrome safer. The extensions   didn't come from the Chrome Web Store or were installed without your   permission.      For your protection, you can only use Chrome extensions that you get   from the Chrome Web Store.      To see a list of your extensions:         Click the Chrome menu Chrome menu on the browser toolbar.   Select Tools.   Select Extensions.         Extensions that have been disabled are grayed out and you won't be   able to re-enable them.   I was hoping I could still enable them by activating developer mode for my extensions but still no luck..  Any tips anyone?  P.s. this is not a duplicate from  as this is related to the chrome v35 update


Hi have an custom listview with following snippet. The problem is the app get crashed when i run the code Here is my code  class MyAdupter extends ArrayAdapter<String>{      Context context;       String[] title ;       String[] description;       int[] images;       public MyAdupter(Context context, String[] title, String[] description, int[] images) {         super(context, R.layout.my_simple_row,title);         this.context = context;          this.title = title;          this.description = description;      }      @Override      public View getView(int position, View convertView, ViewGroup parent) {         Layoutlnflater inflater = (Layoutlnflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);         View row = inflater.inflate(R.layout.my_simple_row, parent, false);          ImageView imageView = (ImageView) row.findViewById (R.id.imageViewl);          TextView textTitle = (TextView) row.findViewById (R.id.textViewl);          TextView textDescription = (TextView) row.findViewById(R.id.textView2);             imageView.setImageResource(images[position]);          textTitle.setText(title[position]);          textDescription.setText(description[position]);          return row;      } }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I understand that to prove this, one considers that each open interval contains a rational number and since the open intervals are disjoint, there exists an injection from the collection of intervals to the rational numbers, which are countable, hence the collection of open intervals is countable. I noticed, however, that this requires arbitrarily many simultaneous, non-defined, choices from the intersection of the rational numbers with each interval in the collection. So, my question is, does this proof require AC?

In the proof of 'Every open set in $\mathbb{R}^1$ is a countable union of disjoint open intervals', we need to pick one rational representative from each of the intervals hence establish the countability.  This seems to depend on the axiom of choice.  Thus I wonder does this property of $\mathbb{R}$ is equivalent to the axiom of choice, that is, is there any construction such that this property is not true once we abandon the axiom of choice?  Thanks!


There are a significant number of words in the English language that end with "-ook".  Most of them (e.g. book, cook, hook, look, nook, rook, took) are pronounced with "o͝ok"; however, spook, mook, and kook are pronounced as "o͞ok".  Is there a non-obvious rule that is at play here?  Why is there a discrepancy?  Edit: This not a duplicate of  as was suggested by @Josh: that was a question on HOW to pronounce "oo" words (by ELLs), not WHY they are pronounced this way.

My German colleagues were laughing at the way I pronounce google, and it led to a discussion.   With words like google, yahoo, poodle and loose, the oo has a sound similar to the German ü sound. With words like good and book, it is more similar to how Germans pronounce a oo sound. For words like door we are not sure if that is the same or different.   The Germans want to know what the pronunciation rules are so they can improve their English. I am guessing that there are no rules, and the pronunciation possibly comes from the original language that the word comes from.  Are there any rules? Is there any reason why there are two different pronunciations? Can non-native speakers work out the correct pronunciation by looking at the other letters in the word or the etymology?


I am wondering is there a shortcut to raise another app's window underneath the current app's active one, so i can quickly toggle the top two windows, as this is a common workflow in my daily work.  I have tried a few window management apps, but couldn't find any that allows me to do this task.  I want to bring the window upfront immediately, not something like Command + Tab that goes through a list of all open windows.

I opened two Google Chrome windows (because I am using multiple Gmails) and when I do the Cmd ⌘ Tab ⇥ shortcut it just shows me other applications that I opened but does not show me the other Chrome windows that are already opened.  How to switch to the other Google Chrome window that I opened using keyboard shortcut?


What is the difference between these two way of defining a method?   var Todo = {};     Todo.abc = function(){     }   and  function abc(){ }

I've recently started maintaining someone else's JavaScript code. I'm fixing bugs, adding features and also trying to tidy up the code and make it more consistent.  The previous developer used two ways of declaring functions and I can't work out if there is a reason behind it or not.  The two ways are:  var functionOne = function() {     // Some code };     function functionTwo() {     // Some code }   What are the reasons for using these two different methods and what are the pros and cons of each? Is there anything that can be done with one method that can't be done with the other?


While studying, I came upon the problem "Two corridors of widths $a$ and $b$ intersect at right angle. What is the length of the longest pipe that can be carried across the two corridors, touching the corner of the wall where the corridors meet?"  The explanation is not detailed, but the answer is shown as  $(a^{2/3} + b^{2/3})^{3/2}$. I have attempted the problem using trigonometry and derivatives, but got stuck early in. Could someone help with this problem?

For one of my homework problems, we had to try and find the maximum possible length $L$ of a pipe (indicated in red) such that it can be moved around a corner with corridor lengths $A$ and $B$ (assuming everything is 2d, not 3d):    My professor walked us through how to derive a formula for the maximum possible length of the pipe, ultimately arriving at the equation $L = (A^{2/3} + B^{2/3})^{3/2}$.  The issue I have is understanding intuitively why this formula works, and exactly what it's doing. I understand the steps taken to get to this point, but there's an odd symmetry to the end result -- for example, is the fact that $\frac{2}{3}$ and its inverse are the only constants used just a coincidence, or indicative of some deeper relationship?  I also don't quite understand how the formula relates, geometrically, to the diagram. If I hadn't traced the steps myself, I would have never guessed that the formula was in any way related to the original problem.  If possible, can somebody give an intuitive explanation as to why this formula works, and how to interpret it geometrically?    Here's how he found the formula, if it's useful:  The formula is found by finding the maximum possible length of the pipe by expressing the length in terms of the angle $\theta$ formed between the pipe and the wall, and by taking the derivative to find when $\frac{dL}{d\theta} = 0$, which is the minimum of $\frac{dL}{d\theta}$ and is therefore when $L$ is the smallest:  $$ L = \min_{0 \leq \theta \leq \frac{\pi}{2}} \frac{A}{\cos{\theta}} + \frac{B}{\sin{\theta}} \\ 0 = \frac{dL}{d\theta} = \frac{A\sin{\theta}}{\cos^2{\theta}} - \frac{B\cos{\theta}}{\sin^2{\theta}} \\ 0 = \frac{A\sin^3{\theta} - B\cos^3{\theta}}{\sin^2{\theta}\cos^2{\theta}} \\ 0 = A\sin^3{\theta} - B\cos^3{\theta} \\ \frac{B}{A} = \tan^3{\theta} \\ \theta = \arctan{\left( \frac{B}{A} \right)^{\frac{1}{3}}} \\ $$  At this point, we can substitute $\theta$ back into the original equation for $L$ by interpreting $A^{1/3}$ and $B^{1/3}$ as sides of a triangle with angle $\theta$ and hypotenuse $\sqrt{A^{2/3} + B^{2/3} }$:  $$ \cos{\theta} = \frac{A^{1/3}}{ \sqrt{A^{2/3} + B^{2/3} }} \\ \sin{\theta} = \frac{B^{1/3}}{ \sqrt{A^{2/3} + B^{2/3} }} \\ \therefore L = A^{2/3} \sqrt{A^{2/3} + B^{2/3} } + B^{2/3} \sqrt{A^{2/3} + B^{2/3} } \\ L = (A^{2/3} + B^{2/3}) \sqrt{A^{2/3} + B^{2/3} } \\ L = (A^{2/3} + B^{2/3})^{3/2} \\ $$  The equation for the formula for the maximum length of the pipe is therefore $L = (A^{2/3} + B^{2/3})^{3/2}$.


There is customer table:   ---+-------+------------+ id + name  + region     +  ---+-------+------------+   There is also orders table:   ---+--------------+------------+----------+----------------+ id + cusomer_id   + product    +  price   +  amount_total  + ---+--------------+------------+----------+----------------+   If I want to form a list of products, which have ever been bought by every customer, in a line with ';' , I make a request:               SELECT GROUP_CONCAT(orders.product separator ';')              FROM orders             WHERE orders.customer_id = customer.id   Everything work fine, however if I want to add some filters there is an error appear:   SELECT customers.id,        (SELECT GROUP_CONCAT(orders.product separator ';')         FROM orders        WHERE orders.customer_id = customers.id) as products  FROM  customers         WHERE customers.region like 'USA'        AND products not like '%fish%'   Query Error: Error: ER_BAD_FIELD_ERROR: Unknown column 'products' in 'where clause'

I need to use an alias in the WHERE clause, but It keeps telling me that its an unknown column. Is there any way to get around this issue? I need to select records that have a rating higher than x. Rating is calculated as the following alias:  sum(reviews.rev_rating)/count(reviews.rev_id) as avg_rating


Let's assume the following class Foo.  struct Foo {   int i;   bool j; };   Why do I get different results from the following lines?  int main(void) {     //I thought the default constructor would be called     Foo foo1;     cout << foo1.i << " : " << foo1.j << endl; // " 4196352 : 0 " --> ctor not called?      //if calling the default constructor explicitly     foo1 = Foo();      cout << foo1.i << " : " << foo1.j << endl; // " 0 : 0" --> ctor called. }    Shouldn't the default ctor be implicitly called?  According to :     If no user-declared constructors of any kind are provided for a class type (struct, class, or union), the compiler will always declare a default constructor as an inline public member of its class.

In the book I'm reading at the moment () it says that if you don't declare a default constructor for a class, the compiler supplies one for you, which "zeroes out each data member". I've experimented with this, and I'm not seeing any zeroing -out behaviour. I also can't find anything that mentions this on Google. Is this just an error or a quirk of a specific compiler?


My primary operating system is Ubuntu 14.04 lts and then I installed windows 8.1 in another partition. Now, I don't need longer windows installation. Can I just erase the windows files and reformat my harddisk to linux format? Because I can't put my file in NTFS format.

I installed Ubuntu 13.04 on my Vista 64 bit machine and I thought it was going to uninstall Vista but it didn't, now I have both systems.  How do I get rid of Vista?


What is the difference in meaning between the following two sentences?  (1) Your idea's sounding great. (2) Your idea sounds great.  To me, as a non-native speaker both sound grammatical, with the second one being more general. Am I right?

A linking verb is a verb which connects a subject to its predicate   without expressing an action. A linking verb is used to re-identify or   describe its subject.      Ex:      Alan is a beast.      Alan seems drunk.   But I would say that some linking verbs can be used with "continuous tenses" & other linking verbs can not, but I am not sure.      (linking verb) to experience a particular feeling or emotion      Ex: I’m feeling a little better today.      Do you still feel hungry?   So, feel in this meaning can be used with continuous tenses  But I would think this sentence "Do you still feel hungry?" does not make much sense because it uses "simple present tense" which expresses something that happens regularly. Noone would feel hungry regularly.  So, that sentence "you feel hungry" would mean "you always feel hungry".      (linking verb) (not used in the progressive tenses): to have a   particular physical quality which you become aware of by touching         adj.         The water feels warm.      Its skin feels really smooth.    says "Speakers sometimes use the Simple Present to express the idea that an action is happening or is not happening now. This can only be done with Non-Continuous Verbs and certain Mixed Verbs."  so, "The water feels warm." could mean "The water is always warm" (simple present expressing things that happen regularly - more or less permanent action)  But "The water feels warm." could mean "The water is warm now" (simple present with non-continuous verb expressing things that is happening now - a temporary action)     : (linking verb) to seem; to appear         adj.         to look pale/happy/tired      That book looks interesting.   In dictionary,      (linking verb) (not used in the progressive tenses): to   give the impression of being or doing something         adj.         She didn't appear surprised at all.       (to somebody) (to be) something (not used in the progressive tenses): to give the impression of being or doing something (synonym:   appear)         adj.         You seem happy.   So, we cannot say "you are seeming happy" or "you are appearing happy".  But I am not sure I can say "You are looking good" (sounds right to my ears) or "That book is looking interesting." (doesn't sound right to my ears)  But we can say "The future’s looking good." ()  So, some verbs has the same meaning but one can be used with "continuous" & the other can not, right?  Ex: "you are looking happy", but "you seem happy".


Let $f$ be the real valued function 0n $[0,\infty]$ defined by $f(x)=x^{\frac{2}{3}}\ln x$ for $x>0$ and $0$ for $x=0$. Is it uniform continuous on $[0,\infty)$?     I think that if we break $[0,\infty)$ in $[0,1]\cup(1,\infty)$ then being continuous on $[0,1]$ it will be uniform there and by showing that its derivative is bounded on $[1,\infty)$   we can collectively say that it is uniform on $[0,\infty)$ , Is it correct?

Let $f$ be a real valued function on $[0,\infty)$ defined by  $$f(x)= \begin{cases} x^{{2}/{3}}\log x & \text{ if } x>0 \\  0 & \text{ if } x= 0 \end{cases}$$  Then which of the following is true?  A. $f$ is discontinuous at $x=0$.  B. $f$ is continuous on $[0,\infty)$, but not uniformly continuous on $[0,\infty)$.  C. $f$ is uniformly continuous on $[0,\infty)$.  D. $f$ is not uniformly continuous on $[0,\infty)$, but uniformly continuous on $[1,\infty)$.  I could see that $f(x)=x^{\frac{2}{3}}\log x$ is continous at $x=0$   But for uniform continuity I thought boundedness of derivative would help   But I found $f'(x)=\frac{2}{3}x^{-\frac{1}{3}}\log x + x^{-\frac{1}{3}}$   This $f'(x)$ is not bounded so i can not say any thing about uniform contunuity.  Please help me to clear this.   Thank you :)  P.S : This was already asked before ( some other person but it was not having enough details so it got closed. I tried to edit that question but someone said I should not edit OP to add more details. I was afraid that may be against the rules of MSE. So, I thought i should ask this separately with my own ideas.


I tried updating to Catalina, but it got stuck on not having enough disk space. It says I have to quit the installer, select a start disk and boot from that, but my system's drive is not in the list of drives that I can select...  So, instead, I started the Terminal, went to the drive through that and I started deleting things. But every time I run df I don't see a change in the amount of disk space. Between reboot changes are persisted though, even creation of new files.   I then installed Mojave on an external drive and mounted the internal drive, it shows up as 52GB free (vs 12GB from df). But when I run df I still see only 12GB free.  I figure there is some sort of place where deleted files are getting moved to in order to provide me with some fancy restore magic for when the installation is done. Where is this magical place and how do I delete files from there so that I can continue the installation?  The answers  don't address my issue because I already know what was eating my disk space.

Catalina update failled mid-way and is stuck due to lack of available disk space. Booted from network drive and deleted files but this only increases purgeable storage and not free disk space. How to turn this purgeable storage into free storage while booted from network drive.


I have no problem with setup "Read-only routing".  My point is if we use "Read-only routing". We need to add the "ApplicationIntent=ReadOnly" into our application connection string. That's beyond our DBA's role.  Is there any other way to let one application such as SAS to connect to the listener and the SQL AG will point it to the secondary?  Many thanks,

We have the ApplicationIntent=ReadOnly properly routing our users to the Secondary ReadOnly replica.  Is there a way to make this the default behavior?  Apparently the default behavior seems to be ReadWrite, and if you don't specify an ApplicationIntent it will redirect to the Primary server.


How to prove that: $ \sup[f(x)+g(x)]\le \sup(f(x)) + \sup (g(x))$  For me, it sounds very logical and obvious but I did not find the way to prove this. I will be glad for any tips.

Suppose $D$ is a nonempty bounded subset of reals. Let $f:D \to \mathbb R$ and $g:D \to \mathbb R$. Define $(f+g)(x)=f(x)+g(x)$. Prove $\sup(f+g)(D) \le \sup f(D) + \sup g(D)$ (also prove that $\sup (f+g)$ exists).   I understand why this is the case, just not how to prove it. Left side is pretty much $\sup  (f(x)+g(x))$ and right side is $\sup (f(x) + g(y))$ for $x,\,y \in D$. Basically $f+g$ has to use the same variable and $f(D)+g(D)$ use different ones. But I don't know how to go about proving this.     The second part of the question is to find a specific example where strict inequality holds.    Let $D=\{a,b\}$ and $f: a \to 1,\, b\to 0, \,g: a \to 0,\, b\to 1$. $\sup f(D) = 1,\, \sup g(D) = 1,\, \sup f(D) + \sup g(D) = 2.$ $\sup (f+g)(D) = 1$ (if we choose a, $f+g = 1+0,\, b,\, f+g=0+1$).


I have an  Dell Inspiron N7010. The G, H, ', 1, 0 and Esc keys no longer work.  I plugged in a external keyboard and it works. I have tried removing the battery and holding the power button for a few seconds. I tried cleaning and resetting the ribbon cable. I tried cleaning the keyboard with air. I tried uninstalling the keyboard from the device manager. I tried disabling the Bluetooth.  Nothing has worked so far. Any suggestions? Should I order a new keyboard?

I'm having problems with my laptop keyboard - specifically, some keys don't work any more.  The problem started three months ago - just three months after I purchased this ASUS K42F - when the left Alt key got busted. I cannot forget that moment because I was editing something important in Photoshop that required the use of such key. I didn't bother to do something about it; I still have the right Alt key anyway.  I was surprised when two days ago, almost half of all the keys in random positions didn't work any more. I haven't spilled any liquids on the keyboard, and I know nobody else has either because I always put this laptop in a vault when I'm out (privacy is a problem here). I've tried everything, from scanning for viruses and spyware to using compressed air, but nothing has worked. I hope someone can help me with this before I'll be obliged to visit the seller whose location is very far from mine. I still have the one year warranty.


Let $f:\mathbb{R}\to\mathbb{R}$ is differentiable and $f(0)=0$. Also $\forall x\in \mathbb{R}$ we have $f'(x)=f^2(x)$. Prove that $f(x)=0$, for every $x$. I tried to use MVT for both derivative and integral. But I got nowhere. I just found out that  $f$ is increasing. for positive values $f$ is non negative. $\forall x>0$, there exists some $c\in (0,x)$ s.t. $f(x)=xf^2(c).$  Intuitively, it seems one can start by a small interval around zero and show that $f=0$ and so on. Any comment!

Let $f:\mathbb{R} \rightarrow \mathbb{R}$ be a differentiable function such that $f(0) = 0$ and $f'(x) = [f(x)]^{2}$, $\forall x \in \mathbb{R}$. Show that $f(x) = 0$,  $\forall x \in \mathbb{R} $.  I first (unsuccessfully) tried using the Mean Value Theorem, but this is in the Integrals chapter so the solution probably involves them. Can't really see where integrals come in here though.  What I've got so far:   (i) Since $f$ is differentiable, thus it is continuous and, hence,  integrable. Therefore $f^2$ is also integrable and as $f'=f^2$, $f'$ is too.   (ii) $f' \geq 0$, $\forall x \in \mathbb{R}$


I am currently attending a IT-Security course at the Tel Aviv University and I stuck with the an assignment task.  Please DO NOT post the solution if you know it. But I would be very grateful for any hint that leads me to the correct result.  Task:  "Eve has managed to intercept the following messages, encrypted by Alice using a XOR cipher:  c1 = 0 0 1 0 0 1 1 1 0 1 0  c2 = 0 1 0 0 1 1 1 0 1 1 0   c3 = 1 1 0 1 0 1 1 0 1 0 1   Eve suspects Alice has been using the same key to encrypt all three messages; moreover, she suspects that the third message (m3) also happens to be m1 XOR m2.  Can you find the key k and the deciphered messages m1, m2, m3?"  Thank you very much in advance for any helpful hint!

I have three messages, each known to be XOR-encoded, with the same key used for each message of this XOR cipher.  Encoded message 1: $e_1\,=\,00100111010$ Encoded message 2: $e_2\,=\,01001110110$ Encoded message 3: $e_3\,=\,11010110101$  I also have an extra information: I know that the decoded contents of $e_1\oplus e_2$ is equal to the decoded contents of $e_3$. How would one go about solving this problem, in order to get the key and decode the contents of the message?


I was just given a 27" monitor that needs a 19v 3.34A power brick. However, the brick is missing. I have a 20v 7a brick from an old laptop. Can I use that, or does the power need to be exact?   In other research I came across this comment. "Voltage means less than the current rating of the power supply. Your power supply should always be able to safely supply more current than the device will draw."

I'm using a common charger for both of my laptops.  The charger is specified at 20 Volts and 3.25 Amperes. My other laptop has a specification of 19 V and 3.42 A.  Is it safe to charge my laptop with chargers whose specifications exceed or are not equal to the mentioned specifications?  I have read somewhere that it may cause some damage if the voltage or amperage is not matching the specs.


Can some one help me point in the right direction or point to some resources that will help me prove that sum of two jointly distributed Gaussian r.v. with a given correlation coefficient is also a Gaussian r.v. Thanks

If $X$ is distributed $N(\mu_X, \sigma^2_X)$, $Y$ is distributed $N(\mu_Y, \sigma^2_Y)$ and $Z = X + Y$, I know that $Z$ is distributed $N(\mu_X + \mu_Y, \sigma^2_X + \sigma^2_Y)$ if X and Y are independent.  But what would happen if X and Y were not independent, i.e. $(X, Y) \approx N\big( (\begin{smallmatrix} \mu_X\\\mu_Y \end{smallmatrix}) , (\begin{smallmatrix} \sigma^2_X && \sigma_{X,Y}\\ \sigma_{X,Y} && \sigma^2_Y \end{smallmatrix}) \big) $  Would this affect how the sum $Z$ is distributed?


After waking up from suspend, graphics look like on the . Ubuntu version: 20.04  Driver: nvidia-driver-450  Graphics card: NVIDIA Quadro P1000  Laptop: Lenovo P52

Kubuntu 20.04, 64 bit GPU: Geforce GT610 nvidia-driver-390 Chrome Version 85.0.4183.83 Intel i5-4430, core 4, 4 thread , 3GHz RAM: 16GB  Each time I go into suspend mode and then resume, Chrome browser displays the current tab as full of sand of colors, something like dithering in image processing.  Other tabs display glitches too. The current solution is to close and reopen the browser. I tested nvidia-driver-418 but got a black screen problem and reinstalled nvidia-driver-390. The problem is more evident in Chrome, but it sometimes appears in vscode in small areas. There, hovering the mouse over the affected place or resizing the window fixes the problem. In Kubuntu the avatar of the user in the application launcher also shows dithered.  I tested in the same machine with fedora 32 workstation(gnome), nvidia driver, and had the same problems with Chrome browser.  Could it be a GPU problem? Thanks in advance for any directions in how to fix the problem or information on what is causing it.


Let $ \omega = dx_1 \wedge dx_2 + dx_3 \wedge dx_4 + \cdots + dx_{2n-1} \wedge dx_{2n} \in \mathbb{R}^{2n}$. Find $\omega^{n}$ (in respect to $\wedge$)  When I say "$\omega^{n}$ (in respect to $\wedge$)" I mean the exterior product of $n$ $\omega$'s.  I tried writing  $$(dx_1 \wedge dx_2) (v_1,v_2) = \det \begin{pmatrix} d{x_1}(v_1) & d{x_1}(v_2)\\  d{x_2}(v_1) & d{x_2}(v_2) \end{pmatrix} = d{x_1}(v_1)d{x_2}(v_2) - d{x_1}(v_2)d{x_2}(v_1) $$  $$ (dx_3 \wedge dx_4) (v_1,v_2) = \det \begin{pmatrix} d{x_3}(v_1) & d{x_3}(v_2)\\  d{x_4}(v_1) & d{x_4}(v_2) \end{pmatrix} = d{x_3}(v_1)d{x_4}(v_2) - d{x_3}(v_2)d{x_4}(v_1) $$  but that wouldn't lead me nowhere.  I know the property $ \omega \wedge (\phi_1 + \phi_2) = \omega \wedge \phi_1 + \omega \wedge \phi_2 $  Then:  $$ \begin{align} \omega \wedge \omega = {} & (dx_1 \wedge dx_2 + dx_3 \wedge dx_4 + \cdots + dx_{2n-1} \wedge dx_{2n}) \\ & {} \wedge (dx_1 \wedge dx_2 + dx_3 \wedge dx_4 + \cdots + dx_{2n-1} \wedge dx_{2n}) \\[8pt] = {} & (dx_1 \wedge dx_2 + dx_3 \wedge dx_4 + \cdots + dx_{2n-1} \wedge dx_{2n}) \wedge (dx_1 \wedge dx_2) \\ & {} + (dx_1 \wedge dx_2 + dx_3 \wedge dx_4 + \cdots + dx_{2n-1} \wedge dx_{2n}) \wedge (dx_3 \wedge dx_4) + \cdots \\ & {} + (dx_1 \wedge dx_2 + dx_3 \wedge dx_4 + \cdots + dx_{2n-1} \wedge dx_{2n}) \wedge (dx_{2n-1} \wedge dx_{2n}) \end{align} $$ but I'm not sure that's what I'm supposed to do...  Thanks.

I need some help:  Define a 2-form on $R^n$ by $\omega=dx_1\wedge dx_2+dx_3\wedge dx_4+...+dx_{2n-1}\wedge dx_{2n}$. How to compute $\omega^n:=\omega\wedge\omega\wedge\ldots\wedge\omega$?


If a human places their hand on a wooden desk, the sense of touch and solidity is actually provided by the repulsion effect of the electron shells of the atoms in the hand and desk giving feedback to the various sensors in the human body.   Can these two things actually physically touch at the atomic level?   In this case we are defining "touch" as the atoms of the hand and desk coming as close to each other as the atoms in the desk are to each other normally.  Using only human muscular power to close the distance, can it be proven that a hand and the wooden desk have physically touched as per the given definition?

If you've ever been annoyingly poked by a geek, you might be familiar with the semi-nerdy obnoxious response of      "I'm not actually touching you! The electrons in the atoms of my   skin are just getting really close to yours!"   Expanding on this a little bit, it seems the obnoxious geek is right. After all, consider Zeno's paradox. Every time you try to touch two objects together, you have to get them halfway there, then quarter-way, etc. In other words, there's always a infinitesimal distance in between the two objects.   Atoms don't "touch" each other; even the protons and neutrons in the nucleus of an atom aren't "touching" each other.  So what does it mean for two objects to touch each other?   Are atoms that join to form a molecule "touching"? I suppose the atoms are touching, because their is some overlap, but the subatomic particles are just whizzing around avoiding each other. If this is the case, should "touching" just be defined relative to some context? I.e, if I touch your hand, our hands are touching, but unless you pick up some of my DNA, the molecules in our hands aren't touching? And since the molecules aren't changing, the atoms aren't touching either?  Is there really no such thing as "touching"?


One of the "benefits" of earning 200 rep points is that fewer ads are displayed to you. Instead of seeing three zones (Leaderboard Top, Leaderboard Bottom, and Sidebar), you see only one (Sidebar).  Now I put "benefits" in quotes because I personally don't consider less advertising (especially on SO) to be beneficial. Of course, as the "ad guy", I really don't care because the loss of impressions are statistically negligible, but as a member I feel that I'm missing out on something.  We work hand-in-hand with each sponsor to make sure their ads are high quality and relevant, and we won't even talk to companies with a product/service that we know is a poor fit. And now that there's no more AdSense, that's the only thing we see.  There are so many awesome products/services that I've found through relevant ads, most of which solved problems I didn't even realize I had (or were solvable). , for example, has very recently "changed my life". And of course, there's no other way I'd find out about these, because I don't spend a whole lot of time reading reviews, etc.  So long story short... I think the "reduced advertising" thing should be changed to work as follows:      On the User Profile page, there would be a Checkbox that reads "Show Reduced Advertising". The Checkbox remains hidden until the member reaches 200 rep. Upon reaching 200, the box gets automatically checked.   Basically, it would work exactly the way it did before, except you get the option to turn off reduced advertising.  And yes, of course I'm biased. But still, Good ads are are a Good Thing.

I understand a lot of people really dislike ads and are happy to have the reduced ads privilege at 200 reputation.  Personally I've really come to appreciate SO, and in support I don't mind seeing ads as it generates income for SO/SE. If I had the option, I would choose to see the regular amount of ads because I like this site.  I think it would be good to give a user with more than 200 reputation the option to support SO and choose to see the normal amount of ads or use the privilege to see reduced ads.


Is there a technical term for when the first sound of a movie is heard while the screen is still black? A hypothetical example: we hear the sound of howling wind for a second or two before we see an establishing shot of a mountain range.

I saw this several times in different movies, but I don't understand what is this supposed to mean. The main idea is when the scene is about to change, for one second or so we still see the picture from the old scene, but the sound is already coming from from the upcoming scene. Why do they do this? What's the purpose of this technique?


Let $R:=\mathbb{R}^{[0,1]}$ and let $m:=\{f\in R:f(0)=0\}$. Prove, that $m\in Max(R)$.  I don't understand this exercise. How steps I must do?

Well, the problem I'm trying to solve is this:      Let $A$ be the ring of all continuous functions from $\mathbb{R} \to \mathbb{R}$. Show that $M = \{f \in A: f(0)=0\}$ is a maximal ideal of $A$.   I tried to show that if $J$ is an ideal of A that properly contains M, so $J = A$: we know that there is a function $g \in J$ with $g(0) \neq 0$. So, we have that $$J \supseteq \langle g, M\rangle=\{ag+f;a \in A, f\in M\}$$   I tried to show that 1 $\in$ $\langle g,M\rangle$. However I'd have to find some function $h(x)\in A$ such that $h(x)(ag+f) = 1$, but this function $h$ has to be different from 0 for all x $\in \mathbb{R}$, so I don't know how to find this function.  My second idea to solve this problem was prove that the quocient $A/M$ is a field. We have that $$A/M = \{h(x) + M; h(x) \in A\},$$ but again I have the problem to show that all elements of $A/M$ are units.  If someone could help, I would be really grateful (:


Let's say I'm a good Stack Overflow citizen: I have a question, I search on SO and on google to see if someone's asked the same thing, and I can't find anything that shows up, so I go ahead and post a well-written question on SO. Then later it gets closed, because it's a duplicate question for something that I wasn't able to find on my initial search. Great, the system worked.  Is there ever a case where I should delete the question I posted? Why or why not? Do duplicate questions cause much resource bloat for the site?

What should I do when I see a question that is a duplicate of another one?   Should I answer it? Should I downvote it? Should I comment? Should I edit the question to indicate it's a duplicate? If I can, should I (vote to) close the question? What happens when I vote to close as duplicate? Or: Why did a comment with my name on it just appear? Should I flag it for moderator attention? What about similar or related questions?


In Python, say I have a string that contains the name of a class function that I know a particular object will have, how can I invoke it?  That is:  obj = MyClass() # this class has a method doStuff() func = "doStuff" # how to call obj.doStuff() using the func variable?

What is the best way to go about calling a function given a string with the function's name in a Python program.  For example, let's say that I have a module foo, and I have a string whose content is "bar". What is the best way to call foo.bar()?  I need to get the return value of the function, which is why I don't just use eval. I figured out how to do it by using eval to define a temp function that returns the result of that function call, but I'm hoping that there is a more elegant way to do this.


I've created a Google Sheets document intended for daily use by more than a dozen people. Text inputted in two of the columns is set up, via conditional formatting, to change colour based on the name entered (Smith = Red, Baker = Blue, Williams = Green and so on). I'm also running a script that forces all entries in these columns to be capitalised.   The issue I have is that all users need to be able to move the column entries up and down as and when required. For example, a job may be scheduled at 6am, then need to be moved down to an 8am slot.  When that happens, the formatting breaks and has to be replaced.  I understand there may be a way to lock or force the formatting using a control column/row and a script, but nothing I've tried seems to work. Any help or pointers would be much appreciated!

I would like to protect the formatting of a cell (or a range of cells) in a Google Spreadsheet, but still allow changing the data in that (or those) cell(s).  For example, I want to add a validation rule on a cell that says the cell has to contain a number between 1 and 10, and I would like others to be able to change the value in that cell, but not the validation rule itself.  How do I do that?  So far I was only able to completely protect the cell (content + formatting) or not at all (the user can change the content as well as the formatting).  To me this seems to be an important functionality when adding access rights to spreadsheets. Is it possible that it is completely missing from Google Spreadsheets?


I am building an app that uses a tagging system like SO. I don't want to except any non-alphabetical characters, but I do want to allow actual letters of any language. Using a filter to only allow certain letters seems unreasonable, as I don't have a collection of all possible letter of every language, so I think the right way to go around it would be to block the characters that aren't allowed. But even then, there are 1000s of characters that should be blocked.  How should I go around it? Is there some magical array out there that holds all these characters? How do other products usually tackle this?  Would love ideas, thanks!

How can I use Unicode-aware regular expressions in JavaScript?  For example, there should be something akin to \w that can match any code-point in Letters or Marks category (not just the ASCII ones), and hopefully have filters like [[P*]] for punctuation, etc.


While most sources seem to agree that death is an important part of being electrocuted, some believe that injuries caused by electricity also fit the definition.  Electrocute: to kill (a person or animal) by electric shock.  Electrocute: to kill by electricity.  Electrocute: to kill someone by causing electricity to flow through their body.  Electrocution is death caused by electric shock, electric current passing through the body.     Electrocute: Injure or kill someone by electric shock.  Electrocute: injure or kill someone by electric shock.   So do you have to die, to have been electrocuted?

Is it correct to say I electrocuted my friend if he was only injured by electricity?


I have a multiple-entry Schengen Visa issued from the Italian Embassy. I have entered one time from Italy; can I enter into any other Schengen country during my second entry?

My wife was just issued a multiple entry visa by France, which is good for one year.  Our first trip will be to France, the issuing country.  My question is: after we leave the EU and return, must future trips also start in France? Or may we go directly to (say) Greece from the US on a later visit?


If a diamond Moderator uses the Close Votes review queue and chooses "Leave open", what happens?   Does their vote count as just one of several that might kick the question out of the queue, or does it get kicked out right away? If the question is removed from the queue right away, are all of the other close votes dismissed, or do they stay?   It's clear what happens if the Moderator chooses "Close"; it's a binding close vote, just like if they vote to close from elsewhere. It's less clear what happens if they go the other way.

It takes  clicking "leave open" in the close-vote queue to remove the question from the queue.  How about diamond mods?  Do they remove it from the queue in one click, or not?


This theorem is stated for only subsets of Rn. I was wondering if this theorem is true for subsets of general metric space. And what about general topological spaces?

Let $X$ be a metric space. Prove that if every continuous function $f: X \rightarrow \mathbb{R}$ is bounded, then $X$ is compact.  This has been asked before, but all the answers I have seen prove the contrapositive. Realistically, this may be the way to go, but is there way to exhibit an unbounded continuous function (under the assumption $X$ is not compact) without appealing to results beyond introductory real analysis (e.g., the solution I've seen involves the Tietze Extension theorem)?  Because we're working with metric spaces, it's clear that the assumption that $X$ is noncompact (towards proving contrapositive) will lead us to extract a sequence of points in the space with no convergent subsequences. But how can we infer the existence of an unbounded continuous on the space knowing only about some sequence of points in this space (without using anything too advanced)?


I have just shown via the Taylor expansion for $\sin(\frac{1}{n})$ that the series  $$ \sum_{n=1}^{\infty}\left(\frac{1}{n} - \sin\left(\frac{1}{n}\right)\right) $$  is in fact convergent and now I'm asked to find the radius of convergence for the series  $$ \sum_{n=1}^{\infty}\left(\frac{1}{n} - \sin\left(\frac{1}{n}\right)\right)\cdot x^n ,\; x\in\mathbb{R}$$   and I'm not sure how to approach this. I have tried the ratio test but it doesn't go well and the Cauchy-Hadamard doesn't seem to work either.  Any ideas?

I think the radius of convergence for  $\displaystyle\sum_{n=1}^{\infty}\left(\frac{1}{n}-\sin\left(\frac{1}{n}\right)\right)x^n$, $x\in \mathbb R$ is:   $r^{-1}$=$\lim_{n\to \infty}$$|\frac{a_{n+1}}{a_n}$|=1   so we get that $r$=1.  But how can I show it formally?  After that, I have to show that $\displaystyle\sum_{n=1}^{\infty}\left(\frac{1}{n}-\sin\left(\frac{1}{n}\right)\right)x^n$ is uniformly convergent in the interval $[-r,r]$. Can I maybe use Weierstrass majoranttest? What can I use as majorant serie?


I am defining a macro, and would like to run other macro's on any sub/superscripts given to it. For example, I would like to define it such that something like:       \myMacro_{lower}^{upper} -----> \operatorname{something}_\someMacro{lower}^\anotherMacro(upper)   Where both sub/super-scripts would be optional. How would this best be done?    Prior works:    provides a neat solution when we are just interested in a superscript.  might be the correct solution to use, but it seems like it might be overly complex - is there a simpler solution that avoids adding the xparse package (as the first solution manages)?

I like to format my integrals so that there is less space between the integral sign and the integrand, more space between the integrand and differential, and so that the differential is upright. However, it is tedious to type out the formatting repeatedly. I wrote a command,  \newcommand{\intf}[4]{\int_{#1}^{#2} \! #3 \, \mathrm{d}#4}   So that the properly-formatted integral is easier to type, e.g. typing in \[ \intf{a}{b}{x^2}{x} \] gives    However, this command requires 4 inputs. If I didn't want the upper or lower limits, I could omit their inputs but I would still need to write out the brackets, e.g. \intf{}{}{x^2}{x}. In the long run, however, this gets tedious as well, and looks messy in the code! It would be super if I had some command where I could just write ^ and _ as necessary, e.g. \intf^{b}{x^2}{x}  So, I'm wondering two things: (a) Is there some preexisting package that has a pre-formatted integral command? (b) Is there an easy way to change the above command so that it can take modifications such as ^ and _ as required?  Thanks!


I'm trying to debug NTLM authentication issue. One of my ideas was to capture the network traffic and look thougth it. In my case NTLM authentication is going over non-stardart port (6901). Of course, Wireshark can't detect it. But there is no NTLM (NTLMSSP) protocol in the list in Decode as menu. I can't do like . Is there a way to ask Wireshark to decode traffic as NTLM? Or I need to modify captured traffic, e.g. change TCP port or somehow another?

I am running Wireshark on my linux machine and i have simple python web server running on localhost:8080  I am capturing only local port 8080. When i open browser on localhost:8080 wireshark captures huge amount of tcp communication (as page loads with all resources) but there`s no HTTP only TCP...   Why i cannot capture HTTP on custom port ?


When I have two faces that are close together I can see through face in front depending on the several factors.  The camera's zoom impacts this a lot. The farther zoomed out I am the worse this is.  Perspective/Orthographic impacts this. Orthographic reducing the problem but not fixing it.  The angle I view this from impacts it. Head on being the worst and 90 degrees being the best.  How can I minimize this issue?  Example:  Zoomed out   Zoomed in   EDIT: This appears in both edit mode and object mode but is much more prevalent in edit mode.

I'm having an odd issue - When I try to zoom in on a detail using my MMB, the "camera" in the 3D view seems to be cutting off the exterior surface of my object and showing me the inside instead. I'd expect this behavior, but only when I was much more zoomed in.  If I zoom out a bit (one click on the scroll wheel) then I can see the exterior as I intend.  Is there any way to adjust this behavior?  Thanks!


Recall the following classic result:  Cayley's Theorem Let $G$ be a group, and let $\operatorname{Perm}(G)$ be the group of set-theoretic bijections $G \to G$. The function $g \mapsto (h \mapsto gh) : G \to \operatorname{Perm}(G)$ is an injective group homomorphism.  Corollary Let $G$ be a finite group of order $n$. Then $G$ is isomorphic to a subgroup of $S_n$.  One may ask if Cayley's Theorem is "sharp", i.e. is it possible to embed a finite group $G$ in a smaller symmetric group than $S_{\lvert G \rvert}$? Let's say that a group $G$ is sharp if $G$ does not embed in $S_n$ for any $n < \lvert G \rvert$.  My question is: which finite groups are sharp?  This seems hard to answer in general but I'd be interested to learn what (partial) results are known. Here are some quick observations:   Let $G$ be a cyclic group of order $p_1^{a_1} p_2^{a_2} \cdots p_k^{a_k}$ with $p_1, \dots, p_k$ being distinct primes and each $a_i \geq 1$. Then $G$ embeds in $S_n$ with $n = p_1^{a_1} + p_2^{a_2} + \cdots + p_k^{a_k}$. If $k > 1$ then $n < \lvert G \rvert$, so $G$ is not sharp. The quaternion group (of order $8$) is sharp. If $n > 2$ then $S_n$ is not sharp, since it embeds in itself and $n < n!$   It also makes sense to ask if infinite groups are sharp (with the same definition), and I'd be interested to hear results there as well! Obviously, any countably infinite group is sharp.

It is well known, that any finite group of order $n$ is isomorphic to a subgroup of $S_n$. Let’s call a finite group $G$ incompressible iff it is not isomorphic to any subgroup of $S_{|G|-1}$ . Does there exist some sort of classification of incompressible groups?  What I currently know:     Any  non-trivial incompressible group has non-trivial center    If the center of a group $G$ is trivial, then it acts faithfully by conjugation on $G \setminus \{e\}$.     If an incompressible group is non-trivially decomposed into a direct product of two its subgroups, it is isomorphic to $C_2 \times C_2$   One can construct a faithful action of $H \times K$ on $H \cup K$. It is defined as $(h, k)h_0 \mapsto hh_0$ and $(h, k)h_0 \mapsto kk_0$ for $h, h_0 \in H$, $k, k_0 \in K$.  $|H| + |K| \geq |H||K|$ iff either one of the groups is trivial, or both of them are isomorphic to $C_2$.  $C_2 \times C_2$ is the only possible group and indeed is not contained in $S_3$.  I also conjecture, that «direct product» in this statement can be replaced with «semidirect product», but do not know how to prove that.     All cyclic $p$-groups are incompressible   If $p$ is prime, then $S_{p^n - 1}$ does not have an element of order $p^n$      $Q_8$ is incompressible   $S_7$ does not contain $Q_8$ as a subgroup


Here is the well-known proposition, I assumed that $K$ is compact subset of $\omega^\omega$ and it contains an open Set $N_s$, so $N_s$ is clopen and thus it is compact. If I can show $N_s$ can not be covered by a finite subcover, the solution is done, but I don’t know how to start, can you please help me?

Could someone give me an example of a Polish space, in which the interior of each compact set is empty? I guess it is trivial, but can't find such an example.


I would like to generate a number between 0 and 9999 for an android application , that I would increment each time. The generated string must be fixed size. For example, for 0, I would like to have '0000'              for 1, I would like to have '0001'              etc.  Any ideas would be welcome. thanks

How do you left pad an int with zeros when converting to a String in java?  I'm basically looking to pad out integers up to 9999 with leading zeros (e.g. 1 = 0001).


I am having trouble with unchecked casting. I know this happens because T is an Object but not every Object is a T. My question is how would I fix this to implement T in ArrayList<T> without suppressing warnings?  public class AdjMatrix <T extends Object> implements Blah<T> {     public T[] vertex;      public AdjMatrix()      {         this.vertex = (T[])(new Object[RANDOM_NUMBER]);                  }      public ArrayList<T> neighbours(T vertLabel)      {         ArrayList<T> neighbours = new ArrayList<T>();          neighbours.add(vertex[SOME_NUMBER]);          return neighbours;     } }   Thanks for you help!

Due to the implementation of Java generics, you can't have code like this:   public class GenSet<E> {     private E a[];      public GenSet() {         a = new E[INITIAL_ARRAY_LENGTH]; // error: generic array creation     } }   How can I implement this while maintaining type safety?  I saw a solution on the Java forums that goes like this:  import java.lang.reflect.Array;  class Stack<T> {     public Stack(Class<T> clazz, int capacity) {         array = (T[])Array.newInstance(clazz, capacity);     }      private final T[] array; }   But I really don't get what's going on.


Does Ubuntu run alongside Windows 7? How much space does it need? Using Windows Installer LTS.

I need my pre-installed version of Windows 7 (or any other version of Windows), how could I install Ubuntu without erasing it?


In the end of Star Wars Episode VI: Return of the Jedi, Anakin, Yoda and Obi-wan's spirits appear in a vision on Endor.  Obi-wan and Yoda look old (as they are when die), but Anakin is young.   Why is Anakin the only one to appear young if, when he died, he was old and deformed?

One of the changes made to the Special Editions of Star Wars: Episode VI: Return of the Jedi was at the end of the film.  Luke sees 3 ghosts during the celebration on the forest moon of Endor, Yoda, Anakin, and Obi-Wan.  In the Special Editions, the actor who played Anakin earlier in the film, Sebastian Shaw, is replaced with Hayden Christiansen who played young Anakin in Episodes 2 and 3.  My question is, why is Anakin the only one de-aged?  Shouldn't Obi-Wan also be his younger self, along with Yoda?


My laptop is running Ubuntu 20.04 LTE 64-bit/Gnome. I want to install the Desktop App downloaded from Web for Linux . The file is Breitbandmessung-linux.deb. The information says it is  Download für Linux (64-Bit) Ubuntu ab Version 16.04 / Debian ab Version 8 / KDE neon ab Version 16.04 / Mint ab Version 18  How can I install this software?

How do I install a .deb file via the command line?


do you use a comma when telling/asking people/things? For example(s)  Do you want to go eat tomorrow, Nathan? Check me out, Nathan. Commas, people, commas! Just sent you a message, Nathan. Just sent you a text message, man!   I have been taking some journalism courses at my respective college, and I have become addicted to correct grammar, punctuation, and AP-style methods. I cannot stop analyzing correct, as well as, incorrect texts/writings in my daily life. I aim to live a correct-grammar life in everything I write. I also just discovered this site, and I love it. Thank you for reading!

I see a lot of people saying things such as      Nice work, Nick   Or     Thanks, Mat   Is the comma really needed? I'm not 100% sure because my spelling and grammar is not great, but I think it reads very strange.


In my shell script after executing a few commands, I'm getting the output below:  Name      English    Maths    science   Social studies ------    --------  --------  -------- --------------- James     20        25        30        40  (many values) (or)  Roll Num   Name     English   Maths   science   Social studies ---------  ----    --------  -------  --------  ---------------   1        James     20        25        30        40  (Many values)   I want to print the values based on a column heading match.  Example: cmd(matching Maths) test.txt  o/p:25   I have tried few awk and sed commands,But I didn't get proper output.  Can someone help me how to get this?

I have the following file:   id  name  age 1   ed    50 2   joe   70      I want to print just the id and age columns. Right now I just use awk:   cat file.tsv | awk '{ print $1, $3 }'   However, this requires knowing the column numbers. Is there a way to do it where I can use the name of the column (specified on the first row), instead of the column number?


I have installed Ubuntu 18.04 LTS on my HP Pavilion series laptop. After installing this version of Ubuntu, right click is not working of my touchpad. How can I solve this?  BTW:  does not have any solution which which is working for me. PS:- Problem remains after selection area in gnome-tweak-tool

I'm experiencing a serious problem with the new Ubuntu 18.04:  System Dell XPS 13 with a freshly installed Ubuntu 18.04 LTS.  Problem description The touchpad provides only primary button (single click and double click), but no secondary button. In particular, when using the "test Your Settings" option in Settings -> Devices -> Mouse & Touchpad, any click on the touchpad is signaled as primary button, no matter where I click (left or right side of the touchpad). This remains the case even after I change the Primary Button from Left to Right (in Settings -> Devices -> Mouse & Touchpad -> General).  In comparison, an external mouse connected to my laptop (via usb) works fine: it provides both primary and secondary buttons with sides corresponding to the choice of Primary Button (in Settings -> Devices -> Mouse & Touchpad -> General).  This may be related to   Any ideas?  Update: Meanwhile, I found out that in addition to the solution proposed by EntropyWins, one can also control this touchpad behavior via the Tweaks tool (a.k.a. gnome-tweaks) under Keyboard & Mouse -> Touchpad -> Mouse Click Emulation. In any case, as EntropyWins explains in his answer, this is not a bug.


I have the following Python code: import loader  def encode_files():     loader = loader.Loader('','','',False, False)  loader = loader.Loader('','','',False, False)  In the body of the function encode_files(), the editor reports an error Using variable 'loader' before assignment. However, loader = loader.Loader('','','',False, False) outside the function is fine. What causes the error of loader inner encode_files(). Thanks in advance!

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


Let $f:[a,b]\rightarrow\mathbb{R}$ be secondly differentiable and $f'(a)=f'(b)=0$. Then there exits a point $c\in [a,b]$ such that $$|f''(c)|\geq\frac{4}{(b-a)^2}|f(b)-f(a)|.$$  I tried to prove it by contradition, however, I didn't make it. I don't know how comes to the term on the right hand side of the inequality.

Let ${\rm f}:\left[a, b\right]\to\mathbb{R}$ be twice differentiable, and suppose   $$\lim_{x\to a^{+}} \frac{{\rm f}\left(x\right) - {\rm f}\left(a\right)}{x - a} = \lim_{x\to b^{-}}\frac{{\rm f}\left(x\right) - {\rm f}\left(b\right)}{x - b} =0 $$  Show that there exists $\xi \in \left(a, b\right)$ such that $\displaystyle{% \left\vert\vphantom{\Large A}\,{\rm f}''\left(\xi\right)\right\vert \geq \frac{4\left\vert\vphantom{\Large A}% \,{\rm f}\left(a\right) - {\rm f}\left(b\right)\right\vert} {\left(b - a\right)^{2}}}$.  I don't know how to start. Any hints ?.


Looking for the language to describe a solution I am looking for...  As a systems admin for an educational institution, I would like to: a) post our tests in an encrypted form b) at a certain time, make the contents available to the user (online or not) c) after a certain time, re-encrypt the file, and/or delete the content.  During the unencrypted time, I would like to prevent copy operations, cut/paste etc. to protect the content...  Is this "mission impossible" type encryption style even possible to protect our content?  If so, what would it be called?  Many thanks for your assistance

I'm not sure if what I'm asking is even a valid question but here goes.  Would it be possible to add a mechanism to an encryption algorithm that would mean it had to be a certain time of the day or a certain day of the year for the encryption to be able to be decrypted.  To Clarify, It should only be decryptable at a certain time eg   4th February or 11.23 am or between 1 and 2 pm    working in a similar way to a time clock on a bank safe.  Obviously this would require encrypted access to an internet timeserver to ensure an unspoofed time signal.   Does this make an sense? Would it be possible? What would the mechanism be?   I asked this on stackexchange.com but this seems a better place.


When having a list like: \documentclass[twoside]{book}  \RequirePackage{enumitem}  \begin{document}  \begin{enumerate}[label=\alph*,start=25] \item an item \item an item \item an item \item an item \item an item \item an item \item an item \item an item \end{enumerate}  \end{document}  we get the error: ! LaTeX Error: Counter too large.  See the LaTeX manual or LaTeX Companion for explanation. Type  H <return>  for immediate help.  ...  l.23 \item a             n item  due to the fact that the counter exceeds 26. When having e.g. HTML the numbering would be like: y, z, aa, ab, ac, ad or at least wrap around back to a? Does something like this exist in LaTeX as well?

I would like to have \alph{counter} for values larger than 26. The following MnWE gives me the error ! LaTeX Error: Counter too large.  \documentclass{article} \begin{document}  \begin{enumerate} \def\theenumi{\alph{enumi}} \setcounter{enumi}{24} \item twenty-five \item twenty-six \item twenty-seven \end{enumerate}  \end{document}   I would like it to behave like one of these:  ..., x, y, z, aa, bb, cc, ..., xx, yy, zz, aaa, bbb, ccc, ... (preferred) ..., x, y, z, aa, ab, ac, ..., ax, ay, az, ba,  bb,  bc,  ... (can be if nothing else works)   A solution without LaTeX3 extensions would be awesome as I cannot run LaTeX3 extensions.