So I've got a brand new laptop for college and it's an Asus Zenbook 14'' with Intel i7 10th gen, and a graphic card- Intel Iris Plus Graphics. Besides running surprisingly slow on i7 processor, Blender won't let me render my animations on the GPU and only works with the CPU. I've tried to search in the Preferences window but I didn't find anything helpful there. What should I do in order to use the GPU?


Lg G4 email verification bypass cant do anything

I recently got an LG G4 phone from a friend and I was really excited until I got to the screen where it said enter the account previously any get. I was so frustrated and thought they set me up but they had also gotten it from a friend.  I did everything the YouTube told me to do except the unknown sources option is grey and it won't let me select it at all (so basically I'm stuck at step 4 of  given in a related question here).  My parents don't necessarily know I have it. I don't have any money or time to send it into the Lg company and I want to get it working so I can stay in touch with my friends when I go on my trip.  What should I do ? I can't install files because it's blocked and can't add an account because every time I do it goes right back to enter the previously synced email. Would putting a SIM card in help ?? How do I completely wipe the system. My trip is in about a week help please.


How to draw arrows between parts of an equation to show the Math Distributive Property (Multiplication)?

There is a part of my paper where I use the distributive property and it might not be clear to the reader to see the operation result (I'm using in proposional logic for a proof). The logic equation (part of) is: $$ (l_{1}) \vee \big( (p \vee q) \wedge (\neg p \vee q) \wedge (p \vee \neg q) \wedge (\neg p \vee \neg q)\big) $$ $$ (l_{1} \vee p \vee q) \wedge (l_{1} \vee \neg p \vee q) \wedge (l_{1} \vee p \vee \neg q) \wedge (l_{1} \vee \neg p \vee \neg q) $$  So I was wondering if there is a way to represent this operation like a 'shower' (see another example in pic ). Maybe there is some hidden magic mathmode command or pkg for this. At last we can also rely on tikz.


Best Azure service for large no of SQL Server databases

We have a dedicated SQL Server machine for a SAAS application with about 200+ databases, the server has E5-2620 with 64 GB RAM. Now we want to move all the databases to Azure, so we're looking into the options: we can either go with a Virtual Machine like (DS13 v2) which can support all these databases, or we can use Azure SQL Elastic Pools like Standard with 400 eDTUs.  My question is: in the long run, and from a management and scalability point of view, which option is better? And also will the Standard Elastic Pool with 400 eDTU's provide the same performance as the virtual machine?  One of the major concerns for us is the performance of the SQL databases in Azure, as this is one of the reason to move the whole application to the Azure so that in the future as the no of users grow we can easily upgrade our instances to cater the increased load.


Unit sphere contains a line segment $[x,y]$, prove x and y are linearly independent.

If the unit sphere of a normed space $X$ contains a line segment $[x, y]$, where $x, y ∈ X$ and $x ≠ y$ , then $x$ and $y$ are linearly dependent and $||x + y|| = ||x|| + ||y||$.  My attempt : If suppose they are linearly independent then there exists c $\in$ s.t. $x = cy$, which gives us that $$1 = ||tx + (1-t)y|| = ||tx + (1-t)cx|| = ||x|||t+c-ct | = |t+c-ct |$$  so for t=0, $$|c|=1 $$ that is about it. Can anyone give me further hints, thanks,


I would know how to cover, with the test class, the catch block in my apex trigger:  APEX TRIGGER:      try{               update olis_updated;         } catch (DMLException e){                 for (OpportunityLineItem o :olis){                        o.addError('There was a problem setting Product_Category__c ');                }           }    TEST CLASS:  I've tried like following, but it doesn't work   // GENERATE EXECEPTION                test.startTest();                  lineItem1.id=lineItem2.id;                  update lineItem1;                test.stopTest();   How can i generate an exeception? Thanks in advantage for any advice.  BR


OpenCV Contours in Python: How to solve 'list index out of range'

Recently I've been working on tracking an object based on contours with openCV in python. I want my code to only draw the largest contour (greater than 20px).  The code works if I start the program while holding a ball up to the camera, but when I remove the ball from the view the program crashes and give me:  if cv2.contourArea(cnt[0]) > 20: IndexError: list index out of range   Anyone know how to solve this?  My code:  import cv2 import numpy as np  #Get current frame from camera cap = cv2.VideoCapture(-1)  #Set size of said frame cap.set(3, 160) cap.set(4, 120)  while True:      _, frame = cap.read()      #Remove Noise and Grain     median = cv2.medianBlur(frame,5)      # Convert BGR to HSV     hsv = cv2.cvtColor(median, cv2.COLOR_BGR2HSV)      # define range of red color in HSV     lower_red = np.array([0,200,0])     upper_red = np.array([40,255,255])      # Threshold the HSV image to get only red colors     thresh = cv2.inRange(hsv, lower_red, upper_red)      #Eliminate small peices of a thresholded image     kernel = np.ones((5,5),np.uint8)     opening = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel)      #Detect contours in an image     contours, hierarchy =  cv2.findContours(thresh.copy(),cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)      #Find only the biggest contour     cnt = sorted(contours, key=cv2.contourArea, reverse=True)[:1]      #If there is a "biggest contour," then check to make sure it is the right size     if cnt != None:         if cv2.contourArea(cnt[0]) > 20:             target = True         else:             target = False;          if target == True:             cv2.drawContours(frame, cnt, -1, (0,255,0), 3)         else:             print 'False \n'     else:          print 'No Contours Detected \n'       cv2.imshow('Frame',frame)     cv2.imshow('Threshold', thresh)      k = cv2.waitKey(5) & 0xFF     if k == 27:          break   cv2.destroyAllWindows()   Thanks for any help.


Simple SVG from Illustrator or Inkscape fails to show

I just installed Blender with brew cask install blender. I tried to import an SVG with File > Import > Scalable Vector Graphics and it did not show. I made a simple SVG file with a circle in both Illustrator and Inkscape and I don't see it in the window. I zoomed out and still could not find it. Here is my screen:    I read  and . I confirm that I don't have raster graphics and that I exported the Illustrator files with those directions.  Here are dropbox links to the SVG files created: Illustrator circle, Inkscape circle (604B and 2kB respectively).  After importing, the Outliner adds a Curve item:    Clicking the eye of this item to show or hide makes no difference in the viewport.  I am new to Blender. Am I doing something wrong or is this a bug?  Update: I removed the Drobpox links because the question already has a solution, and one can easily redo them with Illustrator or Inkscape.


I am trying to remove some nodes from XML document based on input but getting below error...  The node to be removed is not a child of this node.   XmlDocument document = new XmlDocument();         document.Load(filePath);         if (document == null)             throw new Exception("Unable to load document.");          foreach (string xPath in xPaths)         {              XmlNodeList oldChild = document.SelectNodes(xPath, mgr);             if (oldChild != null)             {                 foreach (XmlNode child in oldChild)                 {                     document.RemoveChild(child);                 }             }         }          document.Save(filePath);   Can anyone help me with what I am missign here.


Easy/relevant way to see a post/fav in SE mobile apps

I am using SE mobile app on Android.  I could not find an easy way to see my posts, my favs unlike in website version of SE. Only way I could find is to browse my notifications, which is an indirect, irrelevant way to do just that.  Is there a direct and relevant way to see a post/fav in SE Android mobile app? Am I missing the point?


C# Linq execute method over results from Distinct() method

I have this code that will execute Console.WriteLine(x) on every object in what Distinct() will return.  objects.Distinct().ToList().ForEach(x => Console.WriteLine(x));   However, how can I achieve the same thing without using ToList()?


Conservative fields - Definition confusion

I have seen several definitions of conservative fields, where we always assume that the domain of a vector field $ \pmb F $ is simply connected before giving the definition of a conservative field.  QUESTION:     If we find a function $ f $, where $ \pmb F = \pmb \nabla f $ , and also   $ \pmb F $ and $ f $ have the same domain, then:      Can we ignore whether the domain is simply connected or not and label   the vector field $ \pmb F $ as conservative ?   Thank you in advance


Change graphic card Mac pro Boot screen disappear

I've just changed the Graphics card on my Mac Pro 3,1. I've installed a Nvidia Quadro FX 4800. Everything is fine, the only thing is the when I boot the Mac the classic grey screen with the Apple logo and a progress bar has disappeared. When pressing the button the screen is black and then it goes directly to the password screen. How can I do to make the silver screen return?


Does upgrading Ubuntu respect my existing partitions?

I've read , but this question is aimed at doing an upgrade using the built-in tools.  I use Ubuntu to create backups of my parents' Windows partition. The filesystem layout looks like this:  /dev/sda1: contains Windows 7 /dev/sda2: contains the Ubuntu root partition /dev/sdb1: drive to keep backups.   The laptop is running Ubuntu 15.04. I'd like to upgrade the system to Ubuntu 15.10. Will upgrading using the built-in upgrade tool (so not using a Live USB) respect the existing partitioning?


Alien visits Earth with flying small parasites

I only remember one scene from this movie from the 80s. A humanoid alien is in a swamplike area on Earth and throws some kind of a detachment (a sub-creature from himself?). This small detachment (about the size of a human palm) flies like some kind of a bio-saucer and attacks a human. The human is inside a car, so this flying little thing thumps against the windshield. Now it looks like a wiggling suction cup, it's eager to get at the human. I suppose it's some kind of a body snatcher storyline from here(?)


Is there religion on 24th century Earth?

In Star Trek, is there any evidence that any sort of religion is still practiced on Earth or on any Human world?  There are other species of the Federation that do still praise a god of sorts, eg. The Klingons with Kahless. But I haven't heard any specific mention of anyone on Earth or on board the Enterprise practicing any sort of religion.  Was religion just one of those ideas that mankind 'grew out of' so to speak, by the time of the 24th century?


Secure all post and get data in framework php

I just had this idea of "preSecure" all userinput data from $_post and $_get. But I was wondering if this is good practice and would like some input on this. Here is what I came up with:  function clean_str($str){     return preg_replace('#[^a-z_ 0-9@.-]#i', '', $str); }  if ($_POST){     foreach ($_POST AS $key => $val){         $_POST[$key] = clean_str($val);     } }  if ($_GET){     foreach ($_GET AS $key => $val){         $_GET[$key] = clean_str($val);     } }   This snippet would simply be run at the beginning of each http request. The clean_str function can be developed to allow other chars and replace characters etc (this is just an example). But I think the first goal are to simply prevent sql injection. The only bad thing I can see with this approach right now is if your "plugin" need to send sql commands from user input. The appraoch above could we wrapped in a function of course and be called if needed. Post and Get are global vars so that would not be a problem.  I'm actually writing my own framework (still a lot of work) that I will release if I ever be able to finish it. The thing is that I often see novice developers add $_POST['userinput'] inside database queries. The code above should make even that okay. Well that was some background of what I'm up to and why I bring this up.  I would be very happy to hear your thoughts. This might not be the best question for Stack Overflow, I suppose I want to open more like a discussion to this approach to share thoughts and inputs. But to formulate my question(s) to this, it would be something in line with: Are there any other approaches that would be faster or more scalable than this, or is equal to this, or can another function complement this approach? Is this approach good practice? Is it okay to overwrite the global vars of post and get data like above?  I know the code above is not object oriented, but it's about the approach of cleaning the users' input datas automatically before running checks on them. I think this will save a lot of code and headaches.  Please share your thoughts with me. As comments are limited here on Stack Overflow, I would appreciate if you reply as answers if you bring new thoughts to this table. Comments are to comment on specific thoughts/answers in this case.


PHP web app hosting considerations and advice - high traffic expected from day 1

I'm in the process of researching hosting providers for a high traffic Facebook application.  The client has over 300,000 likes so we can expect quite a bit of traffic when posts are made about it and there are a dozen of so celebrities involved in promoting it on their end.   The app itself, in staging at the moment, is built with Codeigniter and is running a MySQL database. Only one table, of two, is expected to grow significantly through user interaction with the app.  Most of the traffic will be coming from the UK.  Overall page sizes with all assets loaded will be less than 1mb.  For other similar applications we have used a Cloud VPS with the following configuration:  Monthly Bandwidth - 1TB RAM - 2GB Storage - 75GB CPU - 2 x Xeon 2.33Ghz  Any advice would be great appreciated!


How do you add initialization to auto-properties

I'm used to writing classes like this:  public class foo {   private string mBar = "bar";   public string Bar {     get { return mBar; }     set { mBar = value; }   }   //... other methods, no constructor ... }   Converting Bar to an auto-property seems convenient and concise, but how can I retain the initialization without adding a constructor and putting the initialization in there?  public class foo2theRevengeOfFoo {   //private string mBar = "bar";   public string Bar { get; set; }   //... other methods, no constructor ...   //behavior has changed. }   You could see that adding a constructor isn't inline with the effort savings I'm supposed to be getting from auto-properties.


Why are badges not "unawarded" on deleted questions and answers?

I saw this question on Stack Overflow: , and it made me wonder why badges are not "unawarded" like reputation when questions or answers are are changed or deleted.  Why are badges not unawarded when a question or answer's disposition changes?    There's a related un-answered/un-discussed question at . In the previous question, the authors makes a feature request to unaward them. This question asks why things are the way the are.


I have some discrete times of events and I would like to do a test to see if they are likely to have come from a homogeneous Poisson process.   From this pdf, I see:       REMARK 6.3 ( TESTING POISSON ) The above theorem may also be used to test the hypothesis that a given counting process is a Poisson process. This may be done by observing the process for a fixed time $t$. If in this time period we observed n occurrences and if the process is Poisson, then the unordered occurrence times would be independently and uniformly distributed on $(0, t]$. Hence, we may test if the process is Poisson by testing the hypothesis that the n occurrence times come from a uniform $(0, t]$ population. This may be done by standard statistical procedures such as the Kolmogorov-Smirov test.     However I don't quite understand what to do in practice.  Say my times are   [1, 7, 18, 22, 41, 43, 66, 73, 86, 92]   and the time interval I chose was from $1$ to $100$.  How exactly do I do the Kolmogorov-Smirov test in this example?


What I mean is how does the game increase the CP of an evolving pokemon?  For instance I have a pidgey (278CP) when I evolved it became a pidgeotto (489CP), but when I leveled up my weedle (140CP) it became kakuna (150CP).  With some pokemon it seems to be doubled, others tripled, and some not at all


Dark energy is constantly pulling all objects away from each other with increasing speed. This in turn causes a red-shift of the light from the most distant object where this effect is most profound. This red-shift will gradually increase as the objects move away faster. Is there going to be a time where the objects travelling away will emit light of such long wavelength that they will ddisappear from sight?


They might/could be considered New Year’s resolutions

As I went through my financial and travel records for 2007, I realized that as usual I had made a great many mistakes. I’d like to help you to avoid making the same mistakes, so here they are. They might be considered New Year’s resolutions. Or they might be called Lessons Learned. When it comes to travel, do not trust...()   Q: Can I replace the "might"s with "could"s?


I want to hack my iMac's firmware - or maybe that's a stupid idea, but I got to the conclusion that that would be my only option. And please note that my knowledge of coding is at the level of writing applescripts and Filemaker solutions for my own use so I am way out of my league here. But here's the thing:  I replaced my 2013 imac with a 2019 version and it has no startup chime. Why it was removed, and why it was not made an option, is one of those inane Apple mysteries. Clearly, a lot of people are lamenting this change.   After researching the issue, I learned that the startup chime is embedded in the firmware. Thence came the idea.   So the question to those in the know: Would there be a way to put back the startup chime into my shiny new machine?  Thanks, and I'm sorry if it is the wrong forum, or if the question is unacceptable for using the word "hacking". I am NOT trying to achieve anything nefarious, just a solution for my own use.   PS: I have been aware of the nonworking command line solution, I read it in this very website, I thought it was clear that I was looking for a DIFFERENT solution, involving the firmware, with some creative thinking.  This clearly can be done, Apple could do it if they wanted to, I'm sure some enterprising hacker could do it as well. I'll keep looking.


$$ \begin{cases} \begin{align} &\text{1) }a + 7b + 3c + 5d = 16 \\ &\text{2) }8a + 4b + 6c + 2d = -16 \\ &\text{3) }2a + 6b + 4c + 8d = 16 \\ &\text{4) }5a + 3b + 7c + d = -16 \\ \end{align} \end{cases} $$   Then $(a+d)(b+c)$ equals  (A) -4    (B) 0     (C) 16    (D) -16  Please note that this is a 1 mark MCQ sum.Solving for the linear equations will give you the answer but it will be a lengthy process.There must be some quick succinct step to reach the answer. Please help me out.


I'm trying to change an item in a nested list. I thought this would be very straightforward. I have the following:  temp = [1, 2, 3, 4] my_list = [temp for i in xrange(4)] print "my_list = ", my_list  out: my_list =  [[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]]   So just a normal list of lists. I want to access one item:  print my_list[0][1]  out: 2   As expected. The problem comes when changing the item. I just want to change item in my_list[0][1], but I get the following:  my_list[0][1]= "A" print my_list  out: [[1, 'A', 3, 4], [1, 'A', 3, 4], [1, 'A', 3, 4], [1, 'A', 3, 4]]   Why is it changing the four positions, instead of just one? How to avoid it?


How to permanently allow location access for a website in Safari 11?

The method mentioned in this question no longer works:   Is there some way to achieve the same effective in High Sierra?


Is Ubuntu compatible with laptops that have touch screen features?

Is it possible to install and run Ubuntu on a laptop with touch screen features?


If the derivative of a function is square of it then it is constant

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!


Replacing special ALPHABETS in python string

I am working on a football dataset and am dealing with some exotic names. I would like to ask how do I replace special ALPHABETS that are present in my dataset? These are some of examples of these "exotic" names:  'Lionel Andrés Messi Cuccittini', 'Neymar da Silva Santos Junior', 'Luis Alberto Suárez Díaz', 'David De Gea Quintana', 'Zlatan Ibrahimović'  The special alphabets are é, á, ć, etc (alphabets with a "superscript" above). I want to change them to the "base" form - ć becomes c, á becomes a, so on and so forth.  Many thanks in advance!


Enable 'on the fly' CRS transformation in QGIS 3?

In QGIS 2.8 there is a clear button to 'enable on the fly CRS transformation' in the "project properties" for a new project.  Seen here:   But in QGIS 3.0, I cannot find it to save my life.     Can anyone help?


Showing convexity of a function with the restriction over an arbitrary line

Let $f : \mathbb{R}^n → \mathbb{R}_∞$ be a function and let $C ⊂ dom f$ be a convex set.  $$**Part I**$$ Prove that $f$ is a convex function if and only if $f$ is convex over every line $L_{v,x_0}$ where $L_{v,x_0} := \{x_0 + tv : t \in \mathbb{R}\}$.  i.e. f is convex iff when restricted to any line, it be convex on that certain line.  So essentially to handle this proof I need to show that convexity for $f$ holds when its convex over any arbitrary line, and on the converse it does not hold when $f$ is not convex over that arbitrary line. If $f$ is convex then,  $$\forall x,y \in C, a \in [0,1]$$ it holds that $$f(ax+(1-a)y) \leq af(x) + (1-a)f(y) \space \space\space\space\space\space\space\space\space\space\space\space (1)$$  EDIT: $$**Part II**$$  Let $f : \mathbb{R}^n \to \mathbb{R}_∞$ be a function.   I want to prove that $f$ is convex over the line $L_{v,x_0}$ iff $\psi : \mathbb{R} \to \mathbb{R}_∞$  $\psi(t) := f (x_0 + tv)$, is convex over $I (x_0, v )$.  where $L_{v,x_0}:= \{x_0 + tv : t ∈ \mathbb{R}\}$, and $I(x_0,v):=\{t \in \mathbb{R} : x_0 + tv \in C\}$  Any help is very much appreciated


Why can't I join a friend's world on Minecraft PE?

I'm on my tablet playing Minecraft PE. My boyfriend rang me and asked me to join his Minecraft PE world. However, I can't do it because the game doesn't show his world. What's wrong and how can I fix it?


How can I find the square root using pen and paper?

Okay, I know this is very basic question. I learned 2 methods in school. But now, I forget one.   Here is a simple method that I know.   Find the prime divisors of the number Omit the half of numbers that have been appeared even times multiply the rest   For example you want to find square root of 36. You find the divisors. They are 2x2x3x3. In step 2 they appeared as 2x3. That is 6. Problem is this method works when the square root is an integer number. It doesn't work for numbers that doesn't have integer square root. Like 38.  So my question is how can I find the square root of any arbitrary number using pen and paper?


How to fix the Brazilian daylight saving time (Summer Time) of 2018 in Olson database files?

The Brazilian Government has just issued a law that shifts the beginning of the Brazilian DST (Daylight Saving Time) locally called as Summer Time.   This new DST date will come into force in the next month, to be more precise on 18th of November of 2018. So, we won't have enough time to wait for a new Olson update through the operation system updates, neither downloading a new Olson database package might be enough.  I have downloaded the file tzdb-2018e.tar.tz from . Inside that package I found the file southamerica and I have located the following entry:  ... # From Steffen Thorsen (2017-12-18): # According to many media sources, next year's DST start in Brazil will move to # the first Sunday of November, and it will stay like that for the years after. # ... https://www.timeanddate.com/news/time/brazil-delays-dst-2018.html # From Steffen Thorsen (2017-12-20): # http://www.planalto.gov.br/ccivil_03/_ato2015-2018/2017/decreto/D9242.htm Rule    Brazil  2018    max -   Nov Sun>=1  0:00    1:00    - Rule    Brazil  2023    only    -   Feb Sun>=22 0:00    0   - ...   The comments preceding the entry rule for 2018 matches the old law from the end of 2017, but there's a new law that shifts it to the 3rd Sunday of November of 2018.  How to fix that Olson entry shifting it to the 3rd Sunday of November? I have tried Sun>=3 yet, and it didn't work.


How to implement a 'default' flag that can only be set on a single row

For example, with a table similar to this:  create table foo(bar int identity, chk char(1) check (chk in('Y', 'N')));   It doesn't matter if the flag is implemented as a char(1), a bit or whatever. I just want to be able to enforce the constraint that it can only be set on a single row.


Please help with my homework question:  Define $\{a_n\}_{n=1}^{\infty}$, $\{b_n\}_{n=1}^{\infty}$ as:  $b_{n+1}=\frac{a_n+b_n}{2}, a_{n+1}=\frac{a_n^2+b_n^2}{a_n+b_n}, 0<b_1<a_1$  Prove the limits converge and that $\lim \limits_{n \to \infty}a_n = \lim \limits_{n \to \infty}b_n $.  I have tried to show that they are monotone and bounded, tried looking for a property of arithmetic mean (related to $b_n$) but I'm completely stuck as none of these yielded anything useful.  Any help would be appreciated


Answer should be auto-bountied if it was the only one to ever exist and the reason was for rewarding an existing answer

I posted a bounty on  on May 27, intending to reward it to the person who had a highly upvoted answer that was accepted on May 19. The reason I chose from those available was     One or more of the answers is exemplary and worthy of an additional bounty.   When the time was up, I forgot to actually give the user the bounty. The system didn't automatically give it, even though it was the only answer there when I started the bounty and there are no deleted answers that were ever posted to the question.  I propose that, if the exemplary answer reward bounty reason is chosen and there was only one answer when the bounty was added and none were posted during it, the bounty should automatically be given in full to the pre-existing answer.


How to rotate axis correctly using tikzpicture

I have two coordinate frames which have an offset and rotation between them.  Using the following example I tried to visualized it:  \documentclass{article} \usepackage{tikz} \usetikzlibrary{decorations.text}  \begin{document}  \begin{tikzpicture}[thick]     \draw[-latex] (0,0) -- (4,0)  node[right, text width=5em] {$X$};     \draw[-latex] (0,0) -- (0,4)  node[right, text width=5em] {$Y$};      \begin{scope}[rotate=0,draw=red]         \draw[->] (3,2) -- (7,2)  node[right, text width=5em] {$X'$};         \draw[->] (3,2) -- (3,6)  node[right, text width=5em] {$Y'$};     \end{scope}      \draw[->, postaction={decorate, decoration={text along path, text align={center},text={${\overrightarrow{R}}{\;}$}}}] (0,0) -- (3,2)  node[right, text width=5em] () {};  \end{tikzpicture}  \end{document}     once i change  \begin{scope}[rotate=0,draw=red]   to  \begin{scope}[rotate=20,draw=red]   I get:   How could I place the origin of my X'Y' coordinate frame at position (3,2) in my XY coordinate system?  In addition I would like to place $\overrightarrow{R}$ a bit higher. How could I place it above the vector?


Is it possible to mark or segregate bad blocks on HDD?

Hello I want to know if is it possible to mark bad blocks on HDD for OS to not use them. I don't want to save data written on this blocks, just want to get rid of them.  I found some article where author describe how to partition disk to avoid using bad blocks of HDD.  I count how many MB from the start are OK. And also how many MB from end are OK. It looks like I will lost about 50GB of storage space but it is quite fine for me when the disk will run one year more.  First I split disk to 2 partitions:   From beginning to around 190 GB From 190GB to the end   Then I made surface scan of 2nd partition and everything was OK. I was really happy cause i though that finally I will succeed.  Than I wanted to copy all data from 1st partition to 2nd BUT in some data a problem occurs. I/O error. I'd say it is Read problem but when I open file on which copying failed it runs OK, for example some pdf files didn't copied but I opened them.  What can be problem can it be a Write problem? But why there is a problem when surface scan on whole 2nd partition was fine?  What can I do(except buying new HDD)? Can I somehow do this partitioning and use just partition with good sectors? Will it work? How are data stored on the disk? Can I determine where the data will be written?


In Infinity War, Thanos implies that the reason that he wants to kill half of all life is because life generally grows beyond its means. That is, if too many people are alive, then their will go beyond what their natural resources can comfortably maintain.  However, it is clearly stated that once he has the completed Infinity Gauntlet he is the most powerful being in the universe. Shouldn't he be able to just create more natural resources.  Why doesn't he just use his massive power to fix the problems that made him want to kill half the universe?


Multivariate Normal : expectation of X given Y is doubly-truncated

Let $(X, Y)$ be distributed as a multivariate normal with parameters  $$ \mu = \begin{bmatrix} \mu_X \\ \mu_Y \end{bmatrix} \qquad \Sigma = \begin{bmatrix} \sigma_X^2 & \sigma_{XY} \\ \sigma_{XY} & \sigma_Y^2 \end{bmatrix}. $$   I would like to calculate $E(X | y_1 < Y < y_2)$, where $y_1$ and $y_2$ are constants.  From , I have managed to work out that $$ E(X | Y > y_1) = \mu_X + \frac{\sigma_{XY}}{\sigma_Y} \left[\frac{\phi\left(\frac{y_1 - \mu_y}{\sigma_Y}\right)}{1 - \Phi\left(\frac{y_1 - \mu_y}{\sigma_Y}\right)}\right]\\ E(X | Y < y_2) = \mu_X - \frac{\sigma_{XY}}{\sigma_Y} \left[\frac{\phi\left(\frac{y_2 - \mu_y}{\sigma_Y}\right)}{\Phi\left(\frac{y_2 - \mu_y}{\sigma_Y}\right)}\right] ,$$ where $\phi(\cdot)$ and $\Phi(\cdot)$ are, respectively, the p.d.f. and the c.d.f. of the Normal distribution. I could not figure out how to calculate $E(X | y_1 < Y < y_2)$, though.  I have searched for an answer in similar posts from the Stack Exchange network, but I couldn't get a clue from them that would solve this issue. For the record, here are some of them:


We all know that the speed of light is $299792458~\textrm{m/s}$. Here we use meters as measuring sticks to measure the speed of light . But how is a meter  defined? It is defined using the speed of light. Here there is a weird circular reasoning. How can this be avoided? Do we have to accept the speed of light as $299792458~\textrm{m/s}$ and not measure it at all?


I'd like to use a beep sound in a shell script. Unfortunately none of the methods I found via Google work for me.  I tried  echo -e '\a'  echo -ne '\007'   and the command beep after I installed it via apt.  What could be the reason?


The method returns null pointer exception the null pinter is from serialized objects, I couldn't figure out the error yet

This method is in a class without implementing serializable interface     public String FindVetsMedicalAppointments(String id){   MedicalBooking.getInstance().deserializeMedicalBooking();     for (int i = 0; i < MedicalBooking.mediBookings.size(); i++) {         MedicalBooking.getInstance().deserializeMedicalBooking();         if(MedicalBooking.mediBookings.get(i).getVetId().equals(id)){             System.out.println(MedicalBooking.getInstance().mediBookings.get(i).toString());         }     }     return "END OF APPOINTMENTS";  }   This method is in a class implementing serializable interface    public void deserializeMedicalBooking(){     try{             FileInputStream fileIn = new FileInputStream("Medical Appointments.txt");     ObjectInputStream in = new ObjectInputStream(fileIn);     mediBookings = (ArrayList<MedicalBooking>) in.readObject();     } catch (ClassNotFoundException | IOException i) {} }


Example Input:  foobar@example.com foo@example.com,bar@example.com   Example Output:  foobar@example.org foo@example.com,bar@example.com   So, in "normal" circumstances, it would obviously be easy to do something like:  sed 's/.com/.org/g'   But obviously in this case, I only want the suffix in the first column to be manipulated, I want the second column to be left untouched.  I don't mind what tool you propose to use. But I prefer it to available on a standard linux without needing further install (i.e. something like sed or awk or perl would be more preferable to bobsobscuretoolthatneedsinstalling).


Fastest way to move Collection from Sharded MongoDB Cluster to a another Sharded MongoDB Cluster

I have to move a MongoDB Collection (Size: 1TB+) from Sharded MongoDB Cluster to another[5 shards on both clusters]. During this operation, it is assumed that the accompanying program will be offline, so no need to worry about inconsistent data, but I need to minimize the downtime.  I've tried testing it with mongodump and mongorestore, but looks like that is taking ages to finish.  Please share your experiences for such kind of scenarios.  Note: Cluster has only one collection, so I am open at cluster level sync as well.


Can't join any Minecraft servers (including realms)

A friend of mine owns a minecraft realms server and I can't join.   It says:Minecraft authetication servers are down for maintenance". But the weird thing is that some friends are on the server ,playing. Is that normal? Do I have to wait out?


How to find $\operatorname{Gal}(S/\mathbb{Q})$

Please help me to answer the following problem:  Let $f(x)=x^3-3x-5\in\mathbb{Q}[x]$  Thanks


jQuery: Uncheck checkbox when page is clicked

I am attempting to do two things:   Ensure a checkbox is not checked on page load by unchecking it If a checkbox is checked and the mouse is clicked anywhere else on the screen, it will be unchecked.   For the first part, I have tried:  $(document).ready(function() {        $('#cbox').removeAttr('checked');  });   However, this will not allow me to check it manually once the page is loaded.  For the second part, I tried:  $(document).click(function() {        if ($('#cbox').is(':checked')) {         $('#cbox').removeAttr('checked');     }  });   But the problem with this is that if you click the actual checkbox to check it, the check is fired before this is, so the checkbox is always not checked.  How can I correct this?


Should the canonical link contain a link that will never change, the long version with keywords, or a shortened URL from another domain?

I want to prevent SEO from duplicated content.  I have a separate domain only for shortened URLs which is mainly for sharing purpose.  I plan to set the rel=canonical in the HTML head and redirect to the long-version on request, identified through the unique content-id (similar how stackoverflow does).    Which URL should I advisedly point to, getting the highest potential in regard to SEO? <link rel="canonical" href="https://www.mainpage.com/content/1012921/"> or <link rel="canonical" href="https://www.mainpage.com/content/1012921/this-is-the-original-and-long-version/"> or <link rel="canonical" href="https://sho.rt/yd8eEndSX/">  Content-id wont change, but Domain/TLD (even if not assumed to) could. Shortend Domain/TLD won't never change.


I want to know which word does "they" refer to, in the following statements. The question rises because the subject in the beginning sentence is "someone" which is in singular form. The Statements are as follows:   Simply this: When someone discounts the idea that the whole block universe really exists, and insists instead that it is only what is happening right now that exists, presumably  they mean to include what is happening right now in locations other than where they themselves happen to be.


Forgot password and can't access GRUB menu

I forgot my username and password so I can't log on.   I have seen how to load a recovery boot from the grub menu, but  I can't access mine. It says press esc, but I've tried at least 50 million times and it just counts down from 2 and continues loading.    I've tried holding it and pressing it repeatedly.  I tried pressing shift (even though I have an older version where you press esc) and that didn't work either.  I tried every other butt so many different times and ways with no success. I've also tried guessing my username and password (since I can't remember either) but to no avail.  I also created a Windows 7 boot disc to try and change OS and just wipe my computer, but it doesn't work.    It just takes forever to read the disc and then ignores it and continues loading Ubuntu...   I HAVE NO IDEA WHAT TO DO AND I DON'T WANT TO HAVE TO BUY A NEW TOWER.   My big brother made me this computer but I have a laptop and didn't have space for both in my tiny dorm room. Now I have my own apartment and I NEED to use this.   Is there some way to wipe it externally?   There are no important or relative files since it's so old and I just want to use my computer again... is there anything I could do?


Can I use a Tubular tyre in a Clincher rim?

Just tried it - my trekking clincher rim was too deep, so have to use 4 layers of tape to keep side out of rim, but then tubular started to travel forward even during slow acceleration.  Would you try to use glue on all 4 layers + tubular, some special tape or change rim ?  No surprise seller told me it is possible...


Problem with installing Ubuntu alongside Windows 10 (dual boot)

I wanted to install Ubuntu alongside Windows 10. My ASUS FX553VD-DM234T laptop has a 128GB SSD and a 1TB HDD.   First of all, I made a clean installation of Windows 10 (booted from an USB to do so; not that built-in "reset") and deleted all partitions as soon as I had the chance to (so I got left 2 drives with 100% unallocated space each). I installed windows 10 on the SSD.  Then I created a 800GB partition on the HDD with Windows' built-in tool. 200GB unallocated space left.  Now I followed  guide (seemed to be the one I needed) step by step and I'm certain I didn't forget anything or got anything wrong.  And here's where I'm stuck now: as soon as the installation is done and I can click the "restart now" button, the computer freezes. What I did then (after several minutes waiting) was to force the computer to shutdown (pressing the power button) and try starting it up again and pick Ubuntu where I can chose between this and Windows. It's the same problem, it freezes during the loading screen (if it even gets until there, that is).  I couldn't find any solution, and I'm starting to get pretty frustrated after the third try now.  I don't know if this image helps.     I just thought it seems strange that both show the same drive (the SSD), even though I definitely installed Ubuntu on the HDD only.


"Hidden" function on object in javascript

I want function to be available on a object, but I don't it to be visible if if I console.log it or send it to another function.  var obj = function() {   this.name = 'Bob';   this.age = 23; } obj.prototype.say = function() {   console.log(this.name, this.age, 'thats me..'); }  var pers = new obj(); console.log(pers); // { name: 'Bob', age: 23 }  pers.say(); // Bob 23 thats me..   Would this be good for solution and good practice for that? Or is it a better way to accomplish this in javascript?


How can one use a reversing ring with Nikon G lenses?

So,  (credit to mattdm for pointing it out) says:     Firstly, when you turn the lens around you obviously lose the CPU connection between the lens and the camera, so say goodbye to autofocus, metering (in most cases) and aperture control (though I’ll come back to that)   Then:       The advantage of this old lens is that it has a manual aperture ring, which neatly neutralises the loss of automatic control mentioned above.   So, since G lenses don't have an aperture ring, aperture can't be controlled anyhow if we reverse the lens?    Secondly, is it practical that we set the metering and the aperture (manually) before taking the lens out and reversing it?  Is there any other way to get around this problem in G lenses (assuming that the camera bodies have the manual focus, aperture, metering controls)?


Calculating Field from text to integer using ArcMap

I'm using ArcGIS 10.7 trying to calculate a speed field (for my data of roads in California) really simply such that roads = 45 and highways = 65. I know I need to use an if then statement but I'm not too familiar with Python or ArcGIS so I need a function that will allow me to say if the text string includes "FWY" OR "HWY" OR "RTE" return 65 and else = 45. Does anyone know how I could get this done? I'm fine computing with some error as its for an intro class.


SQL Server 2008 select date only from field

I have a table with dates & times in columns.  I need to select the date portion only from a column named last_date.  I see all the information on selecting, but they do not include a column name.  Could someone point out how to select the date portion from a field in a table using the column name??  Thank you


Stopping a .py file from running in background using kill -9 doesn't work

I have a .py file running in the background, invoked with:  python file.py &   Now I try to stop it as using:  $ ps -fA | grep python root     31032     1  0 14:41 ?        00:00:00 python home/file.py $ kill -9 1   This does not work. I thought kill -9 was a sure fire way to shut down a process using its pid, but it seems weird that the pid for the .py file is 1 in the first place.   How do i stop this file?


I have filenames like:  Some Text (1).jpg Some Text (2).jpg .. Some Text (15).jpg Some Text (16).jpg .. Some Text (101).jpg Some Text (102).jpg   And I would like to add 0 befor the numbers, so that I have always 3 numbers. The upper examples would become:  Some Text (001).jpg Some Text (002).jpg .. Some Text (015).jpg Some Text (016).jpg .. Some Text (101).jpg Some Text (102).jpg   Is there any way to automate that?


Does anyone knows what are special items required for Pokemon go gen 2 evolution and how to obtain them? I observed that some of the evolutions require new items, but i am currently not getting them on poke stops.


1. How is the electric field set up in a wire by a battery so that we can  assume that potential at a node is constant?  2. What happens to the electric field across a resistance which makes voltage 'drop'?     Assume the following circuit:      The battery sets up some electric field throughout the wire, with a component along (parallel to) the wire (otherwise, there is no current). Zooming into the wire,   Here I display only the component of the electric field and electron velocity that is along the wire. As the electron moves a distance d, the work done on it by the electric field is Eqd. This work is non-zero. In other words, electric potential energy of the electron varies with the distance it travels along the wire - and thus so does potential. How, then, is potential on a node the same?    Now, add a resistive load:    The potential at all points on the wire above the battery is 10V, below it - 0V. Considering the above - how is this so?    NOTE: I am aware that a non-ideal wire has resistance. My question lies with what resistance has to do with a difference in potentials in the first place - and why voltage drop is not CAUSED BY a charge's distance from the terminals of the battery.


This is a passage from a :     Sometimes Neal would end the conversation or abandon it while she was still making her point, and she'd just go on arguing long after he'd checked out.   What does checked out mean? I tried looking for the term in the dictionaries, but I couldn't find a definition that fits the context.


How do I find the Excel column name that corresponds to a given integer?

How would you determine the column name (e.g. "AQ" or "BH") of the nth column in Excel?  Edit: A language-agnostic algorithm to determine this is the main goal here.


Maximal ideal $M$ such that $\Bbb Z[x] /M \simeq \Bbb Q$

Consider the ring $\Bbb Z[x]$.  Does there exist a maximal ideal $M$ such that  $\Bbb Z[x] /M \simeq \Bbb Q$ ?  I don't think so, because $\Bbb Z[x]$ is not field.


Is there any tool that can calculate the AUC value from a ROC curve if I already know how many samples are true positive, true negative, false positive, false negative out of 500 samples?  Specificity and sensitivity are also known to me.


Are window glasses transparent or opaque to infrared radiation?

I have been trying to understand this concept to identify on the best option to reduce temperature in my room. I have read few article which stated that glass is transparent to IR radiation. ie Beyond the range of UV light (wavelength >400 nm), the energy of visible and infrared light are not enough to excite the electrons and most of the incident light gets transmitted. Thus glass appears transparent to visible and infrared light.  However, contrary to it I saw few article which gave proof of IR imaging where a sunglass (worn by a person) appeared black; which indicates that IR radiation is absorbed in the glass. So which of these two is correct? Any anyone help me in understanding with logical reasoning and help me out for application of this concept to a real world problem.


Where should I ask questions for asking which software library or API or framework to use for specific set of objective requirements?

I understand that the reason for asking questions that solicit opinions or suggestions is to avoid subjective answers and that we want the questions here to be answerable by an objective and definite answer.  But what if I have defined a set of requirements and the question isn't about what's the best out there but rather what could satisfy a set of objective requirements? Isn't that enough to make the question legitimate enough to be asked here?


I need to prove that the ∃x(R(x)→∀yR(y)) is logically valid. I'm trying to understand why this statement is true but I can't figure it out.


Joining Tables and Show Second Table Data In One Row

In SQL SERVER I need to output row data from a table while joining with another table and column data in second table should be comma separated for each first table row by a single query. If there is no matching rows in second table, It should Display NULL. Following are the tables.   Table 1     Table 2  ID  Name    Tlb1_ID CITY 1   A       1   ZZ 2   B       1   XX 3   C       2   GG 4   D       2   HH 5   E       3   JJ   I want the output is as follows Result        ID  Name CITY 1   A    ZZ,XX 2   B    GG,HH 3   C    JJ 4   D    NULL 5   E    NULL


Can I bind a command to a key in Minecraft?

In Minecraft, is there a way to bind a key to teleport to a specific player or place instead of typing a command?


Note: apologies in advance if this is a duplicate, I didn't find a similar q in my search  Say we have a true parameter p. A confidence interval C(X) is a RV that contains p, say 95% of the time. Now suppose we observe X and compute C(X). The common answer seems to be that it is incorrect to interpret this as having a "95% chance of containing p" since it "either does or it doesn't contain p"  However, let's say I pick a card from the top of a shuffled deck and leave it face down. Intuitively I think of the probability of this card of being the Ace of Spades as 1/52, even though in reality "it either is or it isn't the Ace of Spades." Why can't I apply this reasoning to the example of the confidence interval?   Or if it is not meaningful to talk of the "probability" of the card being the ace of spades since it "is or it isn't", I would still lay 51:1 odds that it isn't the ace of spades. Is there another word to describe this information? How is this concept different than "probability"?  edit: Maybe to be more clear, from a bayesian interpretation of probability, if I'm told that a random variable contains p 95% of the time, given the realization of that random variable (and no other information to condition on) is it correct to say the random variable has a 95% probability of containing p?  edit: also, from a frequentist interpretation of probability, let's say the frequentist agrees not to say anything like "there is a 95% probability that the confidence interval contains p". Is it still logical for a frequentist to have a "confidence" that the confidence interval contains p?  Let alpha be the significance level and let t = 100-alpha. K(t) be the frequentist's "confidence" that the confidence interval contains p. It makes sense that K(t) should be increasing in t. When t = 100%, the frequentist should have certainty (by definition) that the confidence interval contains p, so we can normalize K(1) = 1. Similarly, K(0) = 0. Presumably K(0.95) is somewhere between 0 and 1 and K(0.999999) is greater. In what way would the frequentist consider K different from P (the probability distribution)?


What is Tolkien trying to say in this letter?

In a draft of a letter, later recorded as #246, Tolkien makes a strange statement.  I am interested in the first few sentences of the letter, but I will include the remainder for the sake of context.  In the 'Mirror of Galadriel', 1381, it appears that Galadriel conceived of herself as capable of wielding the Ring and supplanting the Dark Lord. If so, so also were the other guardians of the Three, especially Elrond. But this is another matter. It was part of the essential deceit of the Ring to fill minds with imaginations of supreme power. But this the Great had well considered and had rejected, as is seen in Elrond's words at the Council. Galadriel's rejection of the temptation was founded upon previous thought and resolve. In any case Elrond or Galadriel would have proceeded in the policy now adopted by Sauron: they would have built up an empire with great and absolutely subservient generals and armies and engines of war, until they could challenge Sauron and destroy him by force. Confrontation of Sauron alone, unaided, self to self was not contemplated. One can imagine the scene in which Gandalf, say, was placed in such a position. It would be a delicate balance. On one side the true allegiance of the Ring to Sauron; on the other superior strength because Sauron was not actually in possession, and perhaps also because he was weakened by long corruption and expenditure of will in dominating inferiors. If Gandalf proved the victor, the result would have been for Sauron the same as the destruction of the Ring; for him it would have been destroyed, taken from him for ever. But the Ring and all its works would have endured. It would have been the master in the end. Gandalf as Ring-Lord would have been far worse than Sauron. He would have remained 'righteous', but self-righteous. He would have continued to rule and order things for 'good', and the benefit of his subjects according to his wisdom (which was and would have remained great). [The draft ends here. In the margin Tolkien wrote: 'Thus while Sauron multiplied [illegible word] evil, he left "good" clearly distinguishable from it. Gandalf would have made good detestable and seem wicked']. -Tolkien, Letter #246  What was Tolkien trying to say with the following line?  If so, so also were the other guardians of the Three, especially Elrond.  If what is so, and Elrond was especially what?  Is Elrond especially likely to master the Ring?  Is he especially likely to imagine that he could master the Ring?  Note:  This is not a duplicate of "", since I am not interested in who is more powerful.  I am only interested in Tolkien's intended meaning when he wrote the letter.  The other question is in-universe, mine is concerned with the letter itself, not the story or the characters within it.


What's the difference between 127.0.0.1 and 0.0.0.0?

I understand that 127.0.0.1 points to localhost, and so does 0.0.0.0 (correct me if I'm wrong). So, what's the difference between 127.0.0.1 and 0.0.0.0?


Why does a motor draw more current stopped or under load?

I have a small motor connected to DC source, and use the ampere meter to survey the current through the motor. While the motor is rotating, I hold the motor by hand so that it stop. I see the current through the motor increases. Could you help me explain this problem?


How to find the manual of a command when `man ` doesn't work

When man <cmd> or <cmd> --help or <cmd> -h doesn't show you how to use the command, what should you do to get the information you need?  For example, the command enable has no manual page.   Type enable --invalid_option will only show you the usage enable: usage: enable [-a] [-dnps] [-f filename] [name ...] without any explanation. Since the term enable is too generic, searching online for ubuntu terminal command enable will only give you lots of unwanted results.   So is there a best way to get the manual of a command, when man <cmd> doesn't work?


Let $n \in \mathbb{Z}$ with $n\geq2$, and let $a\in \mathbb{Z}$.  Prove that $[a]_n$ is a unit in $\mathbb{Z}_n$ (i.e. $[a]_n$ has a multiplicative inverse) if and only if $gcd(a, n) = 1$.  I know for $[a]_n$ to be a unit, there needs to exist an element $[b]_n$ such that $[a]_n[b]_n$=1. I then know we must end up with $ax+ny=1$ for some integers $x$ and $y$. I am not sure how to get here though.  What I have tried: I have tried $[a]_n[b]_n$=1 and from this, going to $(a=qn+x)(b=kn+y)=1$, but I do not think I can go anywhere from this.  Can anyone help, please?


Let $f(x)=\int_0^1|t-x|t~dt$ for all real $x$. Sketch the graph of $f(x)$, what is the minimum value of $f(x)$    I could not in any way understand how to approach this problem. I think I will be able to plot the graph if I know how the function looks like, so one can wish to avoid that part.   To find the minimum value I thought of differentiating the function. But, there is $x$ on one side and $t$ along with $x$ on the other side. I got really confuse how should I do that. Please help.


Is it okay to use cross entropy loss function with soft labels?

I have a classification problem where pixels will be labeled with soft labels (which denote probabilities) rather than hard 0,1 labels. Earlier with hard 0,1 pixel labeling the cross entropy loss function (sigmoidCross entropyLossLayer from Caffe) was giving decent results. Is it okay to use the sigmoid cross entropy loss layer (from Caffe) for this soft classification problem?


How do you remove Safari 6 on Mac OS X 10.7.4

I understand there was a uninstaller for Safari 6 beta (is that available anywhere?) but it seems no longer available in the Apple Dev Center, and I am on Safari 6 release version.  I need to remove this and revet back to 5.1.7.


Say we have a hollow conducting sphere (with some finite thickness).  If this object has an excess charge amounting to +Q coulomb, and there is no extra electric field in the surroundings (due to other charges), how will the charge be distributed?  Intuitively it seems that the charge will be symmetrically distributed..(all other cases seem too ugly), but in this case how is charge inside the conducting surface zero? Does this have something to do with solid angle and the fact that two cones with vertex at a point in the conductor will have a special relation of the (charge/distance^2) factors? (more charge is distance is more...)  If this is the case can someone please prove that the effect of the two corresponding cones will cancel each other out?


My professor is using questions from other colleges for an assignment. Is this plagiarism?

So I have noticed that there are exact solutions to the exact question I found on an assignment sheet for a unit/class that I am currently doing (the source is from another college's publication on their own assignment). My question is that: is my professor allowed to use this particular question (which is identical in every way, even the wording) in an assignment given to us? Does this not count as being academically dishonest on the professor's part? I know that if I use these solutions it is plagiarism, but isn't using this question in an assignment given to us without any citations or references to the original source, counted as plagiarism on the professor's part?


Down and duplicate votes on my questions as a new user seem like bullying

Lot of people have posted these kind of questions, but mine deals with another perspective of the same problem, so before you cry out duplicate! just hear me out.  I'm a pretty new user on Stack Overflow, and a rookie in the world of Javascript and Jquery.  So I wanted to make something clear...  So I asked some questions based on my knowledge, and what I do not understand, while other more experienced users kept pounding me down and down-voting me.  Well, in my understanding, Stack Overflow was made with the aim that anyone can ask, and anyone can answer.  Old users constantly say This is a duplicate! or Why didn't you check the FAQ!. Now let me ask you something, Will a new user go through all of the Stack Overflow just to see whether it is acceptable to you or not?  OR does he even know that we have a FAQ?  Seriously guys, if you think that a person's question are a waste of time, why do you take the time to down-vote him??  Old users should understand that we are just wanting to get an answer, and not try intimidate us. Give us some space!   I mean seriously, after getting bullied again and again , you think anyone would want to stay on longer?  I agree some new users are just there for spamming, but hey, not all of us are like that!   Just give us some breathing room, and come on, it isn't that hard to be nice to someone.


Simple bijection $\mathbb N_0 \times \mathbb N_0 \to \mathbb N_0$

I'm looking for a 'simple' bijection $$ \pi \colon \mathbb N_0 \times \mathbb N_0 \to \mathbb N_0, $$  where 'simple' in this context means that it should be as easy as possible to define and it should be self-evident that said function is in fact a bijection. It's a quest for convenience - not minimal complexity in any rigorous sense.  Here are a couple of examples I came up with - none of which satisfy both requirements:   Let $\pi(m,n) = c(2^m3^{n+1})$, where $c \colon \{2^m3^{n+1} \mid m,n \in \mathbb N_0 \}\to \mathbb N_0$ is the order isomorphism (or in fact Mostowski collapse) of its domain under the natural ordering, Let $\pi(m,n) = \langle n,m \rangle$ - Gödel's pairing function, Let $\pi(m,n) = m \oplus n$ - the number resulting from '' $m,n$ (where we imagine both $m$ and $n$ as in infinite decks of cards whose $i$th element is labeled with its respective $i$th digit). ...


Question on a proof of: If $H$ is a normal subgroup of $G$ and $|H| = 2$, show that $H \subseteq Z(G)$.

If $H$ is a normal subgroup of $G$ and $|H| = 2$, show that $H \subseteq Z(G)$.   Proof:      Since $|H| = 2$, we have $H = \{e, a\}$, where $a \in G$ is such that $|a| = 2.$   Let $g \in G$ be arbitrary. Then $gHg^{−1} = \{geg^{−1}, gag^{−1}\} = \{e, gag^{−1}\}$.   Since $H$ is a normal subgroup of $G$, we have $gHg^{−1} = H$, that is $\{e, a\} = \{e, gag^{−1}\}$. Hence, $a = gag^{−1}$, and so $ag = ga$. Since $g \in G$ was arbitrary, this means that   $a \in Z(G)$. Also, obviously $e ∈ Z(G)$. Therefore $H = \{1, a\} \subseteq Z(G)$, as required.   My question:      Why is the line "Since $H$ is a normal subgroup of $G$, we have $gHg^{−1} = H$" true? Should it not read "Since $H$ is a normal subgroup of $G$, we have $gHg^{−1} \subseteq H$" ?


When I'm trying to launch Synaptic from Application Manager it asks me for password, I'm writing it ( I doube-checked though) and then the software close.  When I'm trying to launch it with sudo it doesn't work, and everytime when I'm trying to log in with su in terminal, I get Authentication failure and I'm writing the correct password. What's wrong??  Output for sudo -H synaptic  No protocol specified Failed to connect to Mir: Failed to connect to server socket: No such file or directory Unable to init server: Could not connect: Connection refused  (synaptic:32380): Gtk-WARNING **: cannot open display: :0


Does the presence of high level trainers have an effect on low level ones?

I finally got my wife to play and I've noticed she is seeing many more different types of Pokemon despite just starting. When I started I primarily saw Rattata's and Pidgey's.  It appears that we see and can catch the same creatures, and I know that the rarity of present Pokemon increases as you go up in level. So I'm wondering, has the fact that I'm level 7 made it easier for her to catch different types of Pokemon?


Can I publish a paper in a good journal without having an academic position?

This community is introduced by a friend of mine about a week ago and I hope I can write my questions clearly (English is not my first language and I normally have poor communication skills...)   My story: I started my BSc in mathematics about 22 years ago (when I was age 9) and I decided (had to) quit after one painful semester that I still remember it. I studied on my own and a few years later I decided to solve the notorious impenetrable problem the Hodge conjecture. I have not achieved that goal yet but (I think) I have more than enough that people get a fields medal for that. And with my past experiences I believe that I am most probably not wrong in the technicalities (peer review need to be done though)... Nonetheless I can't continue working hard on the problem as I used to because of spending a lot more time on making money (from teaching to laboring jobs) so better to publish whatever I have to possibly get a research job than living a fading life and every-day-increasing severe-depression. But there are many obstacles I believe:   1- Can I publish an article without having an academic position and even without a university degree, at all?   2- I never care about fame and I absolutely don't care if solving some unsolved problem is attached to a particular name (=person) but handing over 18 years of my research to someone who have authority to easily publish it has a high risk of his/her plagiarism temptation thus ruining a possible would-be good life of mine. How can I trust someone?  3- Evaluation of my results is a necessity before I have any claim of that but if it turns out to be valuable enough can I get an academic position without having a physical degree and not going through all many years of official undergraduate and graduate programs in mathematics?     By the way, I hold an Iranian passport which means that I cannot travel Europe/US/Canada/... to present my research with just an invitation for a conference. (Visa-on-arrival is available for Iranian citizens in Mozambique or Samoa airports but I don't think that be helpful; no offense).    PS Please feel free to edit my post if my English is not clear. Thank you all in advance. :)


Do I need a transit visa for my connecting flight in Canada?

I am a Pakistani national, and I am traveling to Jamaica via Canada. I have a valid visa for Jamaica and need to catch my connecting flight from Canada without leaving airport international zone. Do I need visa to get my connection?


Best .NET memory and performance profiler?

We are using ' . What other profiling tools can be recommended that are better for profiling C#  applications?


My question may seem really basic but I struggled to find satisfactory answer. I have started to wonder what is the exact structure of a file in Linux. There are some commands like file or ls that can be used to get some information about the file but I would like to check values of all attributes that file is comprised of. I mean each file has its creator, different important dates, modes, type, encoding, size, actual data etc. Address that informs where the file is located on the hard drive also got to be stored somewhere. Are all of these information stored in the header of the file, ahead actual data or are they in different memory locations? Is there any magic way to get all possible information about the file using bash?


Is normality testing 'essentially useless'?

A former colleague once argued to me as follows:      We usually apply normality tests to the results of processes that,   under the null, generate random variables that are only   asymptotically or nearly normal (with the 'asymptotically' part dependent on some quantity which we cannot make large); In the era of   cheap memory, big data, and fast processors, normality tests should   always reject the null of normal distribution for large (though not insanely large) samples. And so, perversely, normality tests should   only be used for small samples, when they presumably have lower power   and less control over type I rate.   Is this a valid argument? Is this a well-known argument? Are there well known tests for a 'fuzzier' null hypothesis than normality?


I just spilt coffee on my laptop, what should I do?

I have just dropped a half full latté on my company laptop and am not sure what to do.  Is there a way I can make sure that my laptop is usable again?  What steps must I go through to improve it's chances of survival?


I cannot understand why I can't select a group of buttons with Jquery.  This is my HTML (The tbody is built on an ajax call) on the page load.

           Groups

        xxx123	        <button class="btn btn-info delete" type="button" value="xxx123">Delete</button><button class="btn btn-info view" type="button" value="xxx123">View</button>
        // more and more rows omitted

   I'm my javascript file I have (which is placed in document.ready):  $("#tblGroup tbody .view").on("click", function () {     alert("view"); });   I do not see the alert when I click the view button.  However if I type from the console  $("#tblGroup tbody .view")   It will find all of the buttons.    I'm at a total loss why my button click event won't work.


Does "fastboot flash recovery " command work with any android device?

The command is used to flash a recovery. Do you have to use odin like tools to flash it or you can just use adb?  Thank you


How can I find out why my all Oracle database schema packages gets in the invalid status suddenly? When I recompile its, invalid objects compile successfully.  I created trigger "before ddl" but it didn't help me. Also, I query from user_errors to see what the problem is, but there are no errors in that view. Are there any suggestions?  Here is my table audit and the trigger:       create table invalidations (   operation           varchar2(30),   invalidating_object varchar2(30),   invalidating_owner  varchar2(30),   invalidated_object  varchar2(30),   invalidated_owner   varchar2(30),   invalidation_date   date,   ipaddr varchar2(30),   host varchar2(30),   curruser varchar2(30),   currschema varchar2(30),   fgjob number,   bgjob number );  create or replace trigger befddl_trg before ddl on schema declare begin   insert into invalidations   select ora_sysevent, ora_dict_obj_name, ora_dict_obj_owner, d.name, d.owner, sysdate,   SYS_CONTEXT('USERENV', 'IP_ADDRESS', 15)    ,SYS_CONTEXT('USERENV', 'HOST', 16)    ,SYS_CONTEXT('USERENV', 'CURRENT_USER', 8)    ,SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA', 8)    ,SYS_CONTEXT('USERENV', 'FG_JOB_ID', 4)    ,SYS_CONTEXT('USERENV', 'BG_JOB_ID', 4)    from   all_dependencies d    where  referenced_name = ora_dict_obj_name    and    referenced_owner = ora_dict_obj_owner; end befddl_trg;


I run Debian wheezy with Iceweasel as browser and have installed the Flash plugin similar to . Today I read that not only Flash on Windows and Mac also Adobe Flash Player 11.2.202.350 and earlier versions for Linux are vulnerable to . When checking my version in Iceweasel > Tools > Add-ons I was surprised to see that it is an older version, even though I did all upgrades with apt-get.   Does Debian provide updates for the Iceweasel plugin Flash at all? Are they not automatically provided? Do I always have to manually update the plugin?


What are all the Windows 7/8/8.1 updates (KBs) I must skip to avoid Windows 10 upgrading -and nags-?

It's been a time I didn't follow the list of which Windows 7/8/8.1 KBs I must skip since I don't want the unfinished Windows 10 at all. Moreover, I will still consider Windows 10 unfinished (-> unstable) until they release Windows Server 2016  The KBs list up today is scattered all over the Internet, and I am fearing to miss a single one of those.  As far as I know, some of the newer KBs are even old rebranded ones or re-re-re-pushed again and again. The goal is also to not use any external software or post-installation removal tools since I also intend to deploy a script that will block those KBs.  So the question is: can you tell me all the KBs you know that I must avoid?  Any details that can prevent "Telemetry", the "Windows Customer Experience Improvement Program" or prevent the resetting of Windows' settings about updates and privacy concerns is good too ! (Since they are even linked)   In case some cumulative updates (updates that regroup a pack of old ones) contains one of the listed KB, this is still relevant for the question here.  Remarks  There is of course other ways to disable the updates, which are still appreciated here but do consider that they represent a secondary objective of this post. Same applies for saying it's not the correct method to do it, and I do know the list will endlessly get longer.  The reason is that I still prefer doing it manually since I don't even want the files at all in my system. Furthermore, some of these updates had been re-pushed again and again for at least six times ! This is in fact due to the problems that those updates had caused and I don't want any risks to jeopardize my systems because Microsoft have plans for users with our without their consent by doing "Betas To Manufacture".  related:


How can I prove the existence of two values in a given domain Mean value theorem?

Let $f$ be continuous and differentiable on $(0,1)$ such that $f(0)=1$ and $f(1)=0$. There is a $c$ in $(0,1)$ such that $f(c) = kc$, where $k$ is a positive constant.  Show that there exists $a$ and $b$ in $(0,1)$ such that $cf'(a) +(1-c)f'(b)=-1$.


Can you resolve a dispute between myself and my girlfriend? She recently won a game with what I think is a double movement (although there's no mention of this in the rule book).  She put one two letters down to make one word, which also scored linked to another letter. But she then added another letter immediately to the left of the finished word, which then extended the second word. I just don't think you can make a second movement like this in scrabble!    My sister placed down W, D and E, the ones that I circled in red. Is she allowed to do that? I told her it was impossible is it?  Can you resolve this for me please?


How to display all .png files using * in terminal

I am trying to figure out if there exists any command or combination of commands that can display all .png files with a given prefix.  For instance,  In one of my directories, there exist files  life_001.png life_002.png . . . life_020.png and death_001.png death_002.png . . . death_010.png   How can I display all life_***.png files simultaneously or consecutively using a command in linux terminal?  Thank you!


I understand that the Moon's phases are determined by its position in orbit relative to the Sun. (See: ). The "shadow" is not cast by the Earth (a common misconception - this is actually a lunar eclipse), but by the moon's body itself.  It would appear that, in order for the moon to be a new moon, it would have to be somewhere between the Earth and the Sun. However, it would seem that, if we were looking at a new moon, we'd necessarily be looking at the Sun as well.  Why, then, can we sometimes see a new moon at night? Why doesn't it vanish at night for a half-month every month, between its last/first quarters?


Reducing vertices while not reducing quality

This model now has 3,840 triangles I need to reduce it to 1,400 triangles but still keep it's good looks and smoothness.  I have tried Limited Dissolve but it just creates bumps and messes up the vertices. Does anyone have any suggestions? Is there possibly a way to merge all the vertices into one line therefor reducing vertices?  Here is what it looks like:


I'm looking at the following problem:  Prove that for a positive integer $n$, $$\tau(n) \leq 2 \sqrt{n}$$ where $\tau(n)$ is the number of divisors of $n$.  So my idea was to split the set of the number of divisors of $n$ into two subsets: One subset containing the divisors those less than $\sqrt{n}$ and the other subset containing the divisors larger than $\sqrt{n}$ and argue that there must be at most $\sqrt{n}$ in each subset. But I simply can't seem to find that argument! Can you help?


Files are read-only, and refuse to change

I purchased a new SSD and installed Windows 7 64-bit from scratch. I found that my old C: drive, which is now the D: drive, had ownership by an unknown user. I found a way to change the ownerships of everything to my new user ID. However, a lot of files are now read-only, and I can't seem to get rid of the read-only attribute.  I have tried from Windows Explorer, I have tried attrib from an administrative cmd, I have tried cygwin chmod (cygstart -a=runas find . -exec chmod +w {} \;). I see numerous others with the same problem, but don't see any solutions.


How to add a file to the last commit in git?

Sometimes after I did a commit, I found out that I left out a file which should also be included in the commit but actually not. What I often did was commit again.  git add the_left_out_file git commit "include the file which should be added in the last commit"   I think it might not be a good idea to do so, what I want to do is just include the file without adding a commit. Something like this,  git add the_left_out_file git add_staged_files_to_previous_commit   Is it possible?


How do I do single command line command on multiple lines in windows?

Is there a way to extend a command line command on to multiple lines in windows?    Of course, one can simply keep typing, and wrap around, what I'm wondering is if there is a character that you could put at the end of the line that would be a signal that the command is not yet complete.  This could be helpful in formatting a large command, and I've seen this in other command line environments.


the curve $x^3-y^3=1$ is asymptote to the line $x-y=0$. Find the point on the curve farthest from the line $x-y=0$.can someone please explain it to me what the question is demanding?  I cant think it geometrically as I am not able to plot it  Also is there any software to plot such graphs.?


When I boot up my PC, I get these windows security alert message telling me to allow the programs and I have configured to open on startup through the firewall, then if I open an application E.G Steam, it gives me the same message, so I press allow, but the next time I boot the application or PC, they show up again, I've done a virus scan with Malwarebytes to no avail. I am using windows 10    Thanks in advance


Need Server requirement estimates for my application

I am a newbie to Web Development and am trying to estimate the server requirements based on my application configuration.  My application will have to perform simple database look-up based on unique keys which are stored as text.   Page Views: 70k /day Page Size : ~200Kb Server: Apache/ mod_wsgi Application Framework: Django Database Server: MySQL Database Rows: ~40K Columns/Row: 10 Data/Row : ~200 Bytes   I want to calculate the RAM and processing speed requirements. Are there any other parameters that i should consider while estimating the server requirement


Why did Leia rush to Yavin, instead of changing ships or finding tracking device?

Leia openly admitted her belief that they got off too easily from Death Star - they only sent 4 fighters after them instead of hundreds. So she knew she was being tracked (the 1976 novelization 100% confirms that with more details). If so, why in the world did she make Han fly Millennium Falcon straight to Rebel main base on Yavin, leading Death Star straight to it? (they didn't know where the base was before that!) - instead of, say, having Han fly her and Luke to some waypoint and changing ships on the way, or at the very least, scanning Millennium Falcon for tracking devices thoroughly for a week while hanging out in the middle of uninhabited space? NOTE: Leia clearly did NOT give up Yavin to Imperials during interrogation, otherwise Vader and Tarkin wouldn't need the tracking device so much:  " I'm taking an awful risk, Vader. This had better work."  So, there doesn't seem to be any rush to reach Yavin ASAP.


After moving to High Sierra, I realized that I can’t use the normal bootcamp preferences any more, since Windows won’t detect MacOS on the APFS volume. Apples workaround is to hold down the option key during startup to bring up the startup manager.  I have an not officially supported graphics card in my MacPro, it needs a web driver, and I won’t see the startup manager since the web driver loads only after booting the operating system. I could choose the boot volume without seeing the startup manager, but strangely my USB-keyboard is not getting activated… which is strange, why can’t I use the keyboard, does this have anything to do with the graphics card?   So right now, the only way to change the operating system back from Windows to MacOS, is to physically install the old graphics card :-/   I’m disappointed that Apple didn’t warn Bootcamp-users about the whole APFS-compatibility-problem, and also that they don’t provide a fix for the bootcamp manager.  So the question again: is there another way to change the operating system without using the startup manager, OR what can I do to persuade Mr. Startup-Manager to let me use the keyboard?


What's the best way to count the number of files in a directory?

If parsing the output of ls is dangerous because it can break on some funky characters (spaces, \n, ... ), what's the best way to know the number of files in a directory?  I usualy rely on find to avoid this parsing, but similarly, find mydir | wc -l will break for the same reasons.  I'm working on Solaris right now, but I'm looking for a answer as portable across different unices and different shells as possible.


How to calculate Cohen's d effect size intervals for a within-subject design?

I have looked at different web tools for calculating confidence intervals for effect size like Cohen's d for within-subject design. My experience from this survey tells me that there are different ways to estimate within SD because results I got differs on both effect size and confidence intervals. They usually use correlations between variable to estimate pooled variance. Can anyone point me to adequate way of calculating these things?  In addition I mainly use effect size confidence intervals to determine when intervals are non-overlapping the zero effect as hypothesis testing. Does this produce the same results as using a standard confidence interval for the difference directly?  Thanks!


What is $\det(I + A^{50})$ if $A$ has eigenvalues $1$, $-1$ and $0$?

Since $3 \times 3$ matrix $A$ has $0$ as one of its eigenvalues, we know that $A$ is singular. From this we can conclude that $\det(A) = 0$ also $\mbox{tr} (A) = 0$. Further, $\det(A^{50}) = 0$. Now I think that $\mbox{tr} (I + A^{50}) = 3$ but how can I get the determinant from here?


Riemann Zeta Function for Negative Integers

How is it possible that the Riemann zeta function of all negative integers is 0. And why is it that zeta of -1 is the only non-zero value (-1/12)?  Does anyone have a good and/or intuitive explanation for it?


Movie: Creature crawls out of its current hosts mouth into next hosts mouth

I saw part of this movie back in the 80's or early 90's on late night cable TV. I remember the cops were chasing a bad guy, and the bad guy turned out to be possessed by some sort of creature.  This creature had the ability to move from host to host by crawling down their throats (sort of like the Edgar suit in Men in Black). It may have been a bug, or a slug. I think it was black.


Codeblock shows blank area when scrolled down

When looking at  and scrolled down the codeblock I saw this:    Under the horizontal scroll bar there is a blank area still in the codeblock. I have never seen this before so I thought it might be a bug?  I just noticed that the question was edited and it is normal again now but I would still like to know if this is a common thing or not.  Edit: I can reproduce this in: -Google Chrome version  33.0.1750.117 m. -FireFox 26.0 -Internet Explorer 11.0.9600.16518  OS: Windows 7 Professional.


Minecraft combining /testfor names and enchants in one command?

so I made this command to test for if a player has a $50 dollar check on my minecraft server so i can then link that up to a command that will clear the check and pay them. My issue is I can't seem to figure out how to add an enchant to the command. The checks are all enchanted with Unbreaking 10 but I can't seem to figure out how to add that constraint in the command. The command (so far) is:  /testfor @p {Inventory:[{id:"minecraft:paper",tag:{display:{Name:"$50 Check"}}}]}   If anyone would be willing to help me add an enchant constrain so players can't just use anvils to forge checks that would be awesome. (It is a 1.12.2 server btw)  EDIT This question has changed to combining my command   /testfor @p {Inventory:[{id:"minecraft:paper",tag:{display:{Name:"$50 Check"}}}]}    and the enchantment constraint, [{id:34s,lvl:10s}. If someone could help me I've searched to try to find how to do this but I really can't find a way that works.


how to convert a string into operator in c#

Im trying to convert a string called symbol into an operator (+ = - /) for a calculator. Instead of having only one symbol that is already chosen before, the user will choose what symbol to use (the result wont work since its not an operator).  class Program {     static void Main(string[] args)     {         double num01;         double num02;         string symbol;         Console.WriteLine("Input a number");         num01=Convert.ToDouble(Console.ReadLine());         Console.WriteLine("Write the second number");         num02=Convert.ToDouble(Console.ReadLine());         Console.WriteLine("Choose a mathematic symbol");         symbol=Convert.ToString(Console.ReadLine());         double result = ( num01 symbol num02 );         Console.WriteLine ("The result is " + result);          Console.ReadKey();     } }


A natural number $p$ is prime if and only if it has exactly two solution sets $\{x,y\}$ to the equation $$\frac1p = \frac1x + \frac1y, \text{ or equivalently, }p=\frac{xy}{x+y}.$$ Those solution sets are $\{p,p(p+1)\}$ and $\{2p\}$ (where $x=y=2p$).  Is this a known fact about prime numbers? If so, could somebody provide a reference?  A proof is given below. Proof: $(\implies)$ Suppose $p$ is prime. Then if $$p=\frac{xy}{x+y},$$ we can express $x=p^ak$ and $y=p^bl$ for $k$ and $l$ coprime to $p$. Without loss of generality, suppose $0\leq a\leq b$ and $1\leq b$. Then we have $$p=p^b\frac{kl}{k+lp^{b-a}}.$$ Suppose that $b>a$. We then have that $p\not\mid k+lp^{b-a}$, and therefore $b=1$ and $a=0$. Therefore $kl=k+lp$, which implies $k(l-1)=lp$. Thus, $p\mid l-1$. Consider any natural number $m\mid k$. Then $m\mid k(l-1)=lp$. Since $p\not\mid k$, we have $p\not\mid m$. Thus, $m\mid l$. Similarly, for any natural $n\mid l$, we have $n\mid l(k-p)=k$. So $l$ and $k$ have the exact same divisors, and thus $l=k$. Thus, $$k^2=k+kp=k(p+1),$$ meaning $k=p+1$. So $x=p+1$, which implies $y=p(p+1)$. This is the first solution set. Next, consider the case in which $b=a$. Then $$p=p^b\frac{kl}{k+l},$$ so $$p^{1-b}=\frac{kl}{k+l}.$$ Since $k$ and $l$ are coprime to $p$, it follows $b>0$. We also have $$\frac{1}{p^{b-1}}=\frac1k+\frac1l,$$ implying that $$\frac{1}{p^{a+b-1}}=\frac{1}{p^{2b-1}}=\frac1x+\frac1y,$$ so $2b-1=1$ and thus $a=b=1$. Finally, that implies $$p=p\frac{kl}{k+l},$$ so $kl=k+l$ and therefore $k=l=2$. This gives the solution $x=y=2p$. So if $p$ is prime then it has two solution sets. $(\Longleftarrow)$ If $p$ is not prime, then $p=qr$ where $q$ is prime and $r\neq 1$. Then $$\frac1p=\frac1{p+r}+\frac1{q(p+r)}$$ gives us another solution set.


I'm trying to learn about the Singleton design pattern and I found two different ways of only creating 1 instance.  public class Singleton {    private static Singleton instance; // attributes omitted    private Singleton() {     // omissions    }  public static Singleton instance() {     if (instance == null) {         instance = new Singleton();     }     return instance; } // other methods omitted }     public class Singleton {    private static int bound = 1;    public Singleton() {     if (bound == 0) {         throw new RuntimeException(         "Singleton: No more objects must be created");     }     bound--; } }   Which is preferred to use and why? Are they equally as good?


we all know that magnetic field doesn't work....if a current carrying element pulls a metal piece then work is done by the source or the battery not the field.....now let us assume that a bar magnet pulls another magnet / metal above ground and does a work Mgh....now do does this work?  here the source of the field is rotating electrons and we can't blame them to b doing the work ...since electrons rotates in fixed orbit with fixed energies......i dont understand what am i missing?


Why is a predictive distribution wider than mean response distribution?

Why is a predictive distribution wider than a mean response distribution?


How to share files through the local network?

I have a desktop (Ubuntu 13.04 & Win 7 Home Premium) and a Laptop (Ubuntu 12.04), both having WiFi adapters. I also have a WiFi router connected to internet which both my computers can access.  I want to share files between my desktop and my laptop using WiFi (similar to Homegroup on Windows 7 but without using Ethernet cables).  How do I set-up that?  I want to share files using both OSs, if anyone have have information about sharing files with any of the OS please answer!


I am am UK national ( Old British born and  bred )  , currently resident in a Gulf country .  I invited a Bangladeshi  man , a car mechanic known to me  for 6 years and also resident in the same Gulf country   ,  to visit me in the UK for a 1 week holiday  . I said that my own house in London  would be his contact  point and that I would cover any unexpected cost .  He would pay for his own travel to and within the UK.  The application visa was refused – see attached.  If he applied again  , but this time with a  Sponsorship Undertaking  SU07/12  given  by  person in the UK  , is it likely that the visa would be granted .  Note - if I were resident in the UK I would  give such an undertaking .


Problem: Show that if $x_n\to 5$ then $\dfrac{x_n +1}{\sqrt{x_n -1}} \to 3$.  So I know $|x-5|<\epsilon$ and I need to show that $\left|\dfrac{x_n +1}{\sqrt{x_n -1}} -3\right| < \epsilon$.  I tried applying the triangle inequality (and a bit of algebra) to get $$\left|\frac{x_n +1}{\sqrt{x_n -1}} -3\right| \leq |x_n -5| \left |\frac{1}{\sqrt{x_n -1}}\right| + \left|\frac{6}{\sqrt{x_n-1}} -3\right|.$$  From this I know that $|x_n -5| <\epsilon$ and can show that $\left |\dfrac{1}{\sqrt{x_n -1}}\right|<1$. So my only problem is the second part of the sum. I have no idea what to do with it to get everything to be less than $\epsilon$.


Why does python let you access loop variables out of scope

I wrote something like this where I am able to access a variable that is used through pythons in for loop syntax and then being able to access that variable, I was wondering if there is a specific reason to being able to do this  for i in array:     do_something(i)  b = i


Why is this set of polynomials not a vector space?

Why is the set of polynomials $M=\{ f(x)=2\lambda+7\lambda x +4\lambda x^2 + x^3 | \lambda \in $R$\}$ not a vector space over $R$?


Converting georeferenced .pdf to .tiff in ArcGIS for Desktop?

I am attempting to convert a USGS georeferenced pdf to a tiff.  I found this help page, which looks pretty simple:    Except my Conversion Tools do not have "From PDF" (I am running Arcmap 10.2.2).    Does anyone have advice on how to troubleshoot or use another method?


Change behaviour of numpad to dpad in GNOME 3

I'm a long-time Windows user who uses the numeric keypad with the numlock off for navigating text, highlighting it, etc. Shift + Home (7 on the numpad) selects all text till the beginning of the line. In GNOME, pressing Shift + Home on the numpad inputs 7 instead of selecting all text till the beginning of the line.  Is there a way to change the behaviour of the numpad in GNOME 3 to that of the direction pad?


RTL8723DE Working with signal, but never connects

I have signal, but wifi never connects. I use kubuntu 19.04. I tried to follow this steps.  git clone -b extended https://github.com/lwfinger/rtlwifi_new.git  sudo dkms add ./rtlwifi_new  sudo dkms install rtlwifi-new/0.6   And works to show my wifi icon, but I`cant connect (obviusly I put my password).  Then I tried:  sudo modprobe -r rtl8723de && sudo modprobe rtl8723de   But nothing.   What hapend whit this wifi card? Why is so hard to configure?


What is the character limit for a URL, especially if the URL is formed from a GET method of a form.


How do I install Spotify in Ubuntu 16.04

There seems to be a lot of problems with installing Spotify in 16.04. I tried this guide  to make sure I wasn't just screwing up, but it never worked. Turns out, this question is a little out-dated. To help out new users, I'll ask the question, give some information, then answer this.  I'm trying to install spotify in Ubuntu 16.04. I tried a few different guides. Here's the steps I've done in the previously mentioned guide. First, I pasted in  echo 'deb http://repository.spotify.com stable non-free' | sudo tee --append /etc/apt/sources.list   Then I added the key using:  sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 94558F59   Finally I updated and tried installing Spotify using  sudo apt-get update && sudo apt-get install spotify-client


The sum of the series $$\binom{n}{0}-\binom{n-1}{1}+\binom{n-2}{2}-\binom{n-3}{3}+..........$$   $\bf{My\; Try::}$ We can write it as $\displaystyle \binom{n}{0} = $ Coefficient of $x^0$ in $(1+x)^n$   Similarly $\displaystyle \binom{n-1}{1} = $ Coefficient of $x^1$ in $(1+x)^{n-1}$  Similarly $\displaystyle \binom{n-2}{2} = $ Coefficient of $x^2$ in $(1+x)^{n-2}$  Now, how can I solve it after that, Help Required, Thanks


Proving or disproving that a nonidentity cyclic group has at least two generators.

I had trouble proving that a nonidentity cyclic group has at least two generators, but I am starting to think that it has to be disproven. Would I have to disprove it by showing that any cyclic group has at least two generators besides the identity?


Whats this weird images in Thunderbird Mail?

When I go to check my mails in Thunderbird Mail I see weird shapes floating on my email.   On scrolling up-down those image shapes disappears.


Why is my aperture limited to less than the maximum even in manual mode?

Equipment: Nikon D7000 with a 18-105mm lens that comes with it.  Level of photographer: novice   I've read that the aperture levels change depending on focus. Is there any way in manual mode to stop this?   I tried taking photos of some cardinals and had it originally set at f3.5 but when I looked my screen it was at f4.5 and I couldn't get it any lower.


What are Ctools plugin (content type, access, etc), and how does one create them?

What are Ctools plugins, and how does one create them?


Is it possible for a high school student to conduct research into computer science?

I am currently half way through year 10 and I am interested in conducting research into computer science. I am from a public high school in a small town in Australia. I want to go to Massachusetts Institute of technology but sadly my high school doesn't offer a lot of opportunities when it comes to technology but I have taught myself C, Python and currently learning C++. I am nearly through the basics of C++ and I will be learning networking in C++ soon, probably by the next to month or two. I am really really really really interested in conducting research in computer science and can't wait to get started. But i just don't know where to start......How can I get involved in research???


If $\mathrm{Tr} (X)=0$ then there exists $A, B\in \mathcal {M}_n (\mathbb {C}) $ s.t $ X=A\cdot B-B\cdot A $.

Let $X\in \mathcal {M}_n (\mathbb {C}) $ with $\mathrm{Tr}(X)=0$. Then there exists $A, B\in \mathcal {M}_n (\mathbb {C}) $ s.t $X=A\cdot B-B\cdot A $.   It's there a solution that uses Normal Jordan Form?


Applying MVT to function that has limit of its derivative given when $x\to\infty$

Let $f:[0,\infty)\rightarrow R$ be differentiable on $(0,\infty)$ and assume that $f'(x)\rightarrow b$ as $x\rightarrow\infty$.  (a) Show that for any $h>0$, we have $\lim_{x\rightarrow\infty}\frac{f(x+h)-f(x)}{h}=b$.  (b) Show that if $f(x)\rightarrow a$ as $x\rightarrow\infty$, then $b=0$.  (c) Show that $\lim_{x\rightarrow\infty}\frac{f(x)}{x}=b$.  Note: this is exercise 6.2.16 from "Introduction to Real Analysis" by Bartle & Sherbert, that I'm using for self-study.  Part (a) is an easy one, but am stuck with parts (b) and (c).  My solution to part (a) would be as follows:  By definition, $\lim_{x\rightarrow\infty}f'(x)=b$ means that for all $\epsilon>0$ there exists $K(\epsilon)$ such that if $x>K$, then $|f'(x)-b|<\epsilon$. Now, for given $h>0$, it is that $x+h>K$ too, and by MVT there exists $c$ such that $x<c<x+h$ and $f'(c)=\frac{f(x+h)-f(x)}{h}$. As $c>K$, then $\lvert f'(c)-b \rvert <\epsilon$ too, and thus $\left|\frac{f(x+h)-f(x)}{h}-b\right|<\epsilon$ for all $x>K$; which, by definition, means that $\lim_{x\rightarrow\infty}\frac{f(x+h)-f(x)}{h}=b$.  Another note: Bartle & Sherbert book has no solutions for all exercises, but for many of them there exist publicly available solutions. For this one, however, the only solution available is   However, arguments provided there to prove parts (b) and (c) just don't seem rigorous enough to me.


Prevent laptop from going to suspend mode

I want to prevent my laptop (running Ubuntu 12.04) from going to suspend mode(as wifi gets disconnected) while watching video(youtube, totem_player) and especially when downloading files from my Chrome browser. Also, is there a way to detect if the video is playing or not so that the computer may go to suspend mode only when video is not playing or paused. Further, I already tried Caffeine and it is continuously detecting open Video_Player even though nothing is playing (on pause or stop mode). Is there an efficient way of accomplishing this ?


When should I use "shall" versus "will"?

Which is the correct use of these two words, and in which context should one be used rather than the other?


Ubuntu 20.04 : unrecoverable unused space with GParted

I have a 2TB SSD without OS on it, only data, it is on /dev/sda1. It is full but I have about 100GB that I cannot used on it. I have already extended at maximum with GParted. df|grep /dev/sda1 returns : /dev/sda1         1921802432 1824110376          0 100% /mnt/b85107de-9722-4bf5-8e9a-c810fbfb7e76   How to retrieve the unused space ? Thanks beforehand.


I've tried doing this with CSS changing them from float:left & float:right and reversing it under a @media (max-width:820px) query which I'm sure has worked in the past but didn't work.  Tried a simple JQuery:  if ($(window).width() < 820) {    $( ".first" ).insertAfter( $( ".second" ) ); } else {    $( ".first" ).insertBefore( $( ".second" ) ); }   I know this should be so simple but it's just not playing ball, what am I doing wrong?


\includegraphics{picture} yields only a placeholder box

Currenly my issue with \includegraphics is as follows: \includegraphics{example.png} results in the following picture even though the example.png picture is present in the same directory as the main.tex file in Overleaf. . There is no error nor warning regarding the image name or path. Since e.g. the command: \includegraphics{exampleasdf.png} gives a warning that "File 'exampleasdf.png' not found on line", I am under the impression that the compiler finds the image file, but cannot read it? I changed my PDF viewer to native, but it did not resolve the issue. However, the exact same command in a dummy project gives out the desired output. . If I could I would share the the relevant .tex code, but as it is part of my thesis that uses a ready-made-format, I don't know what is and what is not important to share. That is, I would end up sharing pages upon pages of .tex code. It could be that the fault lies in some ready-made setting, but what to look for?


I have named him/he who shall not be named?

I have named him/he who shall not be named. Which of these is correct? I think it should be "him" because "him" is a direct object in this context. In this context, "him/he who shall not be named" is not a proper noun.


Why aren't pins on microcontroller grouped together, close to each other?

Simple question, the curiosity is killing me. Why do microcontrollers (and other IC also, like RAMs) have pins not grouped together?   Like in STM32, for example you have portA and it has 8 bits on one side of IC and the other 8 bits at the opposite corner of IC... Why? It make routing PCB much harder. What is the reason or purpose of such alignment? Why couldn't they put it next to each other? And why do 32-bit uCs (like STM32) have 16-bit wide ports, when they could have 32-bit wide?  The same goes with RAMs - address pins and data pins are scattered almost randomly over the IC. Why?  Inside the IC there are plenty of routing layers, so what's the reason they couldn't add one more to group pins in some logical order?