from  (problem 13):  "For n≤20, which groups U(n) are cyclic? Make a conjecture as to what is true in general. Can you prove your conjecture?"  where U(n) is the group of natural numbers < n and co-prime to n, under the operation of multiplication (mod n)  I find that U(n) is acyclic for n = 8,12,15,16,20, but unable to form a conjecture.


I am trying to install Intel drivers on Steam and when I try to open the Update Manager I get this message 'E:Malformed line 6 in source list/etc/apt/sources.list (dist parse)'   I'm also very new to Linux considering I got Ubuntu yesterday. Any and all help is greatly appreciated. Thanks.


Evaluating sums question $\sum_{k=2}^n \frac{1}{k^2-1}$

I need to use the identity $\frac{1}{k^2-1}=\frac{1}{2}(\frac{1}{k-1}-\frac{1}{k+1})$ to evaluate $\sum_{k=2}^n \frac{1}{k^2-1}$.  I am confused about how to begin this proof.  Also, how am I supposed to use the identity here?  Do I need to use induction?


How to easily and completely disable/enable WLAN (so it cannot be turned on again while travelling)?

Without going into specifics of why I might like to do this, or whether this is a good idea or not, I would like to know how I can disable use of wireless networking on my MacBook Air, either via removal of software or drivers or similar, such that the machine is unable to connect to a WIFI network in any way without I undo those changes.  The intention is for the machine to be unable to communicate wirelessly when out of the house, and for those changes to not be easily reverted until I return (for example requiring some piece of external storage that does not travel with me and which contains copies of whatever I have removed). How can I easily remove and then re-allow WIFI access (without losing my stored profiles/passwords or disturbing anything else)? Is it possible to simply copy a certain app or plugin to an external drive, delete it from my laptop, and later copy it back, again having everything as it was before?  One year later I have been happily using Daniel Lawson's solution below for quite some time now. I have created two applications with automator, one that deletes the .kext, one that restores it from an USB stick. First, copy /System/Library/Extensions/IO80211Family.kext to a USB stick and leave that stick at home. Open Automator, select to create an "Application", then choose "Utilities" from the "Library", then "Execute Shell Script". (I'm translating this from my German menus, so the exact names may differ.) For the "Disconnector" app, enter the following into the text area of the "Execute Shell Script" event: echo YOUR_ADMIN_PASSWORD | sudo -S rm -rf /System/Library/Extensions/IO80211Family.kext  Replace "YOUR_ADMIN_PASSWORD" by your admin password. Then save the app and drag its icon to the Dock. Now, when you are sure you want to be free of all online distractions, click the app icon, and the IO80211Family.kext is gone. Just restart your laptop and you can no longer connect to WLAN:  For the "Reconnector" app, enter the following into the text area in Automator: echo YOUR_ADMIN_PASSWORD | sudo -S cp -r /Volumes/NAME_OF_YOUR_USB_STICK/IO80211Family.kext /System/Library/Extensions/  Replace "YOUR_ADMIN_PASSWORD" by your admin password and "NAME_OF_YOUR_USB_STICK" by the name of your USB stick. Save the app etc. Now when you return home, insert the USB stick that carries the IO80211Family.kext into your laptop, click the Reconnector app icon and then restart your laptop. Now you can connect to WLAN again. Note. There are some security issues invovled when you echo your admin password, because by that it is written to the shell history and can be found there. I don't care, but you might, depending on your circumstances.


Why does "Take Ownership" (and other) context menu (items) have selection limit?

Using . Everything works fine, but it appears there are limits - when selecting more than 15 folders, "Take Ownership" context menu entry disappears. Same goes with files, 15 is maximum. Where does that limit of 15 come from and why does it exist?


Capitalization with quotation marks when the quote is not direct speech

I have this sentence:     We recommend that parents consciously convey the message, "Everybody needs to follow the safety rules" rather than "Do what the babysitter says."   My inclination is to lowercase Everybody and Do. What are the style rules for capitalization of this kind of quote, especially in the middle of a sentence?


Remove the most popular tag from the title using JavaScript

So, I see that  to fight site scrapers. But, this is harmful to User Experience. With browsers like Google Chrome, all I can see is the first few characters of the title, and it becomes annoying to try to find the right tab.  So, my request: Can you remove the tag from the <title> using JavaScript? Crawlers will still see the SEO-friendly <title>, and users won't have their user experience hampered by it. We all win.


Built-in alarm, calendar suddenly talking to me. How can I shut them up?

I use the native Clock app, and my alarm used to just have a normal ringtone. I assume there was some automatic update recently because this morning, in addition to the normal ringtone, there was a robotic voice saying "It is 7:25 AM." Then later I got a notification from the native Calendar app, and in addition to my normal ringtone, the robotic voice announced the text of the notification.  How do I shut this off? It's really annoying and I don't see an option in Settings.


Solving $\lim \limits_{x \to 2}{\frac{\sqrt{6-x}-2}{\sqrt{3-x}-1}}$

I'm trying to solve the following limit.    $$\lim \limits_{x \to 2}{\frac{\sqrt{6-x}-2}{\sqrt{3-x}-1}}$$    Unfortunately, I haven't made any headway.  I tried multiplying by the conjugates of both the numerator and denominator (in 2 different attempts, of course), but ended up with a monster of an expression either time.


How can I clean a lens (fisheye) scratches? I heard about    peanut butter rubbing alcohol car paint scratch removal solution any other? like an abrasive tool etc


How to find remainder of $31^{41^{101}}$ from division by 53?

When we see such a big and difficult to calculate number, we want to use Fermat's little theorem (especially when we see prime number as divider) But how do we approach situation when we have number in power of number in power? And what if we had something like "find remainder of $13^{5^{53}}$ from division by 48". It is already not a prime number, what would we have to change in our solution?


Some of the faces of my model are are dark

I'm currently creating a car in Blender using blueprints, but I have a problem. Some of the faces are dark and don't interact with lighting. I thought that I have , but sub surf don't work for me.


"Viewed" increases with browser refresh (see question 108318)

It seems that refreshing a question's page increases its viewing count. Not every time, but under certain conditions. For example, it seems that the count increases the first time a page is refreshed after it has been loaded for the first time.  If this is happening by chance, I have to visit the nearest casino asap!  I noticed this after posting a question on StackOverflow. I wanted to see whether I had a reply, so I was hitting refresh, every now and then. The count was going up every time I hadn't looked at the page for a large (arbitrary) amount of time. And every time it was going up by 1. It's not like it had received numerous views in the meanwhile. Never did I see a jump in "viewed" of more than one. And it only has 30 something views, so it's not like it's a popular question (unfortunately for me). In all actuality, there hasn't even been a single comment on it yet, let alone an answer.  All this leads me to believe that, contrary to , there really is a buggy viewing count at play here. Unless it's a feature....  :)  FINAL THOUGHTS: As my commenters noted, this question has been addressed  and . However, I find this feature counter-intuitive and actually a hindrance to users that are trying to see whether their question had any true views. There is no point in increasing the views by taking page refresh into account. If there can be a solution that circumvents that, I would be strongly in favour of that.


Existence of an idempotent element in a finite monoid.

I'm trying to show that if $E$ is a finite monoid, then there exists $s$ such that $s²=s$, i.e, there exists an idempotent element in $E$.  What I did is this: Take an element $a$ of $E$, and consider the application $F_a :E\to E$ such that for $x$ in $E$, $F_a(x)=ax$. Now, if $E$ was a group, it's easy to see that $F_a$ is a permutation of $E$ (consider $F_{sym}(a)$)  since $E$ is finite. Then there exists at least one element $x$ such that $F_a(x)=x$. Take $x=a$ we'll have $a²=a$.  But what about the initial case, where $E$ is just a finite monoid?   Thanks.


How can faces be rotated around their individual normals?

In edit mode with these settings:   Face selection Pivot point: individual origins Transformation orientation: Normal   The faces don't rotate around the normals, is there another required setting that I overlooked?


How far are we from the "edge" of the universe?

According the the Big Bang theory, the universe started as a 0-dimensional point of infinite density. Shortly thereafter, it underwent inflation and grew to some measurable size, and continues growing to the present day.  If, when inflation started, the universe was a "ball" of some measurable size, that implies that some of the matter-energy was close to the "outside" of the ball and some was close to the "center", even if there is no "outside" of the ball.  Why is it not possible to determine how far something is from that "edge"? If the answer is that the "edge" is farther away than light travels in 13.7 Gy, I can accept that. It is still some finite distance away, albeit too large to measure.  Am I completely off in my thinking? What is wrong with my logic?


Is there a special restriction on commands executed by cron?

I have a crontab that looks like  0 0 * * * pg_dump DB_NAME > /path/to/dumps/`date +%Y%m%d`.dmp   which works fine when I run it manually, but not when cron runs it. After digging through the logs, I see  Dec 12 00:00:01 localhost crond[17638]: (postgres) CMD (pg_dump DB_NAME > /path/to/dumps/`date +)   It looks like a problem with percent signs, but the man page doesn't even contain the percent character at all, so I thought they were alright.


If $n=p_1^{2a_1}p_2^{2a_2}...p_n^{2a_n}$  Number of divisors of $n$:  $(2a_1+1)(2a_2+1)...(2a_n+1)$  I saw an other similar question, but it is complicated. There should be an more easy answer.


If two functions are defined by the same formula, but have different codomains, are they equal?

It is said for two functions $f,g$ to be equal they must have same domain and codomain and for each $x\in X$, $f(x)=g(x)$.  But shouldn't functions such as $f:\Bbb R \to \Bbb C$ where $f(x)=x^2$ and $g:\Bbb R \to \Bbb R$ where $g(x)=x^2$ still be considered equal functions for example? Even if codomain is different.


Why do objects float in liquids denser than themselves? I know that a balloon floats on water because it has air in it, but why?


Should my custom keyboard's "delete all" button have an image?

I am making a custom iOS keyboard. Here is the current design:    The "delete all text" button (the one with the x that is surrounded by a square) is currently the only key on the keyboard that has an image instead of text. Should I make its function more clear by replacing the image with text?


What are practical advantages of Compact cameras over DSLR?

In the past there was huge difference between amateur and professional cameras, but due to the market demand, companies are producing cheap professional (DSLR) cameras, and more advanced compact cameras.  The price of a DSLR is much higher (e.g. twice) than the price of a compact camera with the same specifications; for example Canon PowerShot and EOS XX0D.  Apart from flexibility of using professional lenses, what is the practical advantage of an expensive DSLR over a cheaper compact camera? The audience of both cameras are ordinary people who wish to take more professional pictures.  Is the quality of pictures substantially different?  Are the pictures taken with Canon EOS or Sony Alpha dominantly better than those taken with Canon PowerShot or Sony CyberShot?


ActiveSupport extends Object with an instance method blank?:  class Object   def blank?     respond_to?(:empty?) ? !!empty? : !self   end end   Could !!empty? be written as empty? instead? Is this a stylistic choice so that it reads easily as a method returning a boolean? Or is there something else?


How to write multiple author name and location?

I am trying to add multiple Author and institute  name with location but it's not working.  What I have tried is:  \begin{document} \title{Multi label classification} \author[1]{John S} \author[2]{Prbhu M} \author[3]{Three} \affil[1]{US}   I am looking for like this:    How to add multiple emails like that with location and institute?  Thanks in advance !


Can a human sized object vibrate so fast it appears invisible to the human eye?

my brother and I are working on a story in which a being's atoms vibrate back and forth so rapidly that it appears invisible, like a plucked guitar string or a plane's propellor.  Is that theoretically possible?   Thanks for any help!


Invalid Input Data Error 000368 Running ArcPy tools in for loop

I am attempting to iterate over all the feature classes in a folder and I'm getting the error 000368. The other solutions in on SE were not helpful to me unfortunately, so I'm posting a separate question. search_grids is a list of point feature classes and searches is a another point feature class.   The points never actually intersect with each other, but I'm using the Select by location tool to select points within a specified distance of each other. This isn't the reason for the error though as I was able to get this to work in the python window in ArcMap.   My code is the following  arcpy.env.workspace = r"C:\workspace" search_grids = arcpy.ListFeatureClasses() searches = r"C:\workspace\search" for grid in search_grids:     arcpy.management.SelectLayerByLocation(grid,"INTERSECT",searches,"97.5 meters","NEW_SELECTION","INVERT")     arcpy.management.SelectLayerByLocation(grid,"INTERSECT",searches,"2.5 meters","ADD_TO_SELECTION","NOT_INVERT")   Why am I getting this error?       arcgisscripting.ExecuteError: Failed to execute. Parameters are not valid.   ERROR 000368: Invalid input data.   Failed to execute (SelectLayerByLocation)


How is Starkiller Base's beam visible from Takodana in The Force Awakens?

On Takodana,      the main characters and various bar patrons can see the planet Hosnian Prime being destroyed by Starkiller Base with their (respective) naked eyes. How did they see this? Is the Hosnian system close enough to see? If it's not very close and they could just see the explosion, how did the light from it reach them so quickly?


Is it possible to install Windows on a separate hard drive without leaving Ubuntu?

I have a laptop with two HDDs. Ubuntu is on the SSD, and I want the Windows install on the HDD.   Relevant specs: Kubuntu 18.10, installed with UEFI SSD is encrypted LVM ext4.  I have partitioned a 150GB section of my second HDD, NTFS.    I have installed an ISO with woeUSB. My assumption is that I boot my live USB and choose the correct hard drive, then any time I boot up I would have the option between Ubuntu/Windows/USB/etc. Is there anything I should do or know that I am missing?  I am editing this to say that my process was much easier and possibly due in part to updates to how Linux and Windows are able to handle boot managing. I will try my best to recall what I did and re-edit with full info at a later time. I believe that due to differences in software, this is in fact not a duplicate.


How does this python factory function work

This is the python function from my pluralsight python class:  def raise_to(exp):     def raise_to_exp(x):         return pow(x, exp)     return raise_to_exp   And the instructor now opens an interactive session and does the following:   from raise_to import raise_to square = raise_to(2), and then goes on to do square(5)   and that produces the result of 25. How or why pass in two distinct arguments? Now I ran a debug on this code and this is what I observed. When I do this:  def raise_to(exp):     def raise_to_exp(x):         return pow(x, exp)     return raise_to_exp  square = raise_to(2)  print(square)   I get : <function raise_to.<locals>.raise_to_exp at 0x00000246D1A88700>, but if I do as the instructor  def raise_to(exp):     def raise_to_exp(x):         return pow(x, exp)     return raise_to_exp  square = raise_to(2)  print(square(5))    I get 25. I would like to know how this works. I know this is referred as a python factory function but how does it work. Is the function storing the first argument for later use with the second argument passed in?


Is it a good idea to give exit/close icon to top along with close button text after the content ends on a modal  If answer is not a good idea, please explain


Why does this syntactic element not get properly highlighted by matlab-prettifier?

I've found that the matlab-prettifier does not highlight all the syntax compared to the original file.  For example, here is a snapshot of part of the file I am trying to include in my document from MATLAB:    As you can see, the "syms" variables show up like how a text command in MATLAB would look like.  However, from my code below, this MATLAB command is not colored typeset like the original.  How I can get this "sys" syntax in MATLAB to show up correctly in my LaTeX document?   Here is my code:  \documentclass{book} \usepackage{amsmath,amsfonts,amssymb,amsthm} \usepackage{xcolor} \usepackage{listings} \usepackage{filecontents} \begin{filecontents}{mat1.m} %% Variables to solve syms r2s r3s th1 th2;  % arm1 x1 = [0 0]; y1 = [0 1]; x2 = [0 1]; y2 = [1 1]; x3 = [1 1]; y3 = [1 2];  % Size figure and draw arms figure('position', [800, 300, 600, 550]); hold on plot(xcirc, ycirc,'m','linewidth', 1); \end{filecontents}  \renewcommand{\lstlistingname}{\textbf{\textcolor{blue}{Matlab Algorithm}}} \renewcommand{\lstlistlistingname}{List of \lstlistingname s}  \usepackage[numbered,framed]{matlab-prettifier}  \begin{document}  \lstinputlisting[ backgroundcolor=\color{blue!05}, style=Matlab-editor, basicstyle=\mlttfamily\small, caption={Draw a simple Fig.}, label={mat1} ]{mat1.m}  \end{document}


Is there a way to have multiple character's saves on the same map with only one account?

Is there a way to have more then 1 character saved on my map while using only one account?  I only have 1 account but there are 3 of us. We want to alternate playing, but with everyone playing on the same map and having their own stuff (position, inventory, ender chest, mod stuff, etc.).  This is just single player, no server and their will be no more then 1 player playing at a time.  the first answer do not work. I still got all my stuff. I did not start like a new guy and it just seems to reset my mod so now. I lost my progress :(  good thing I was not fare lol


I find it easier to get a visa for Portugal, as I have relatives there. But my aim is to spend more time in Italy

I find it easier to get a visa for Portugal, as I have relatives there. But my aim is to 2-3 weeks in Italy, and just a few days to visit my Portugal relatives. If I book my flights  with a 2-3 week gap, will it be a problem to enter Italy?


Why is the code showing me invalid credentials , shouldn't it print Login Successful?

Why is it not able to compare my input and the values from the database ?? I have also printed the values I got from the database after taking the input so that I can compare the input and the database value . This is the java code : public static void clogin(String username, String password) throws Exception  {     String url = "jdbc:mysql://localhost:3306/Bank";     String query = "select * from admin_credentials";     String uname = "###";     String passw = "###";     Class.forName("com.mysql.cj.jdbc.Driver");     Connection con = DriverManager.getConnection(url,uname,passw);     Statement st = con.createStatement();     ResultSet rs = st.executeQuery(query);     while (rs.next()) {         String un = rs.getString(1);          String pw = rs.getString(2);         System.out.println(un + " " + pw);         if (un == username && pw == password) {             System.out.println("Login Successful!!");         }         else {             System.out.println("Invalid Credentials");         }     }           st.close();     con.close();       }  public static void main(String[] args) throws Exception {     Scanner input = new Scanner(System.in);     System.out.println();     System.out.println("Username : ");     String username = input.next();     System.out.println("Password : ");     String password = input.next();     clogin(username,password);       }  } My Database : Username : kushaltodi Password : epson  My Output : Username : kushaltodi Password : epson kushaltodi epson Invalid Credentials


Right from The Philosopher's Stone to The Goblet of Fire, as far as the magical community was concerned, "The Boy who Lived" had lived while Voldemort had been defeated.  It's understandable that Voldemort had created for himself quite a reputation as a evil wizard whose very name made people shudder.  But once he was "dead and gone" , why worry? Surely, his name wasn't "taboo" at that time. The Death Eaters couldn't track the people who said his name openly.


I found this sentence in a book:  A large percentage of the population smokes too much.  The author treated the phrase 'a large percentage of' as singular. I am so confused with the use of verbs after 'a large percentage of' as some folks on the Internet consider 'a large percentage of' plural. Do we have any rules for the phrase? Thanks!


A question on relative homology and quotients

I have some trouble understanding the map on homology which is induced by a quotient map. If $(X,A)$ is a good pair, and $q:X\to X/A$ is the quotient map, is the induced map $q_*$ then given by the map $H_n(X)\to H_n(X,A)$ in the long exact chain, composed with the isomorphism $H_n(X,A)\cong H_n(X/A)$? If yes, why exactly? If no, then what is the best way to compute the induced map on homology of such a quotient map?  Thank you!


How I can create deep copy in angular 2, I tried to use let newObject = Object.assign({}, myObject) but still myObject reflects all the changes done in newObject.


This is the program which was asked in an interview to predict the output         main()   {      char **p = 0;      printf("%d\n", ++p);   }   Can you please let me know why is the answer 4 here?


When did Kakashi and Obito awaken their Mangekyou Sharingan?

In chapter 604 of the manga, it is shown that Kakashi kills Rin. This fulfills the requirement to activate the Mangekyou Sharingan. So that should have been the moment when Kakashi was able to use the Mangekyou Sharingan.   Also, the Yellow Flash was still alive when this happens, so this means that Naruto was not yet born. This clearly points to the fact that from the very beginning of the Naruto series, Kakashi had his Mangekyou Sharingan activated.   When Kakashi first fought Itachi (when Itachi and Kisame appear at Konoha) and faced the Tsukuyomi he was devastated in a moment, even though he had his Mangekyou Sharingan active (though not used). But the next time they face (during the rescue mission of Gara), he was able to withstand it.  Now my first question is, was Kakashi unaware of his Mangekyou Sharingan until he faced Itachi, or was he not proficient in using it. Also why in the Naruto series (I mean the series before the start of Shippuden) didn't Kakashi use his Mangekyou Sharingan?  Now for my second question, in the same chapter, a few pages back, just when Kakashi strikes the blow at Rin, Obito's vision starts to fade as he can sense Rin dying. Does this mean Obito's Mangekyou Sharingan was awakened at the same time? We know that Kakashi and Obito shares the same "other dimension" because of the same Sharingan that the both use (not the same eye, but the eye of the same Uchiha). So does the same apply for their activation of Mangekyou Sharingan?


how to restore windows 7 to a know working state every time it boots

A couple of days ago my mother asked me to set up a computer at her house, she wants to use it to basic web browsing, video chat and nothing more.  The problem is, neither my mother nor my sister know anything about using or maintaining a computer.  What I want is to have a working base install of windows 7 and just discard everything installed, downloaded, ... when it reboots. That way I can set up a partition just for saving files and whatever they do the computer will always return to a working state at start up.  can that be done?  PS: Sadly linux is not an option since my sister wants to be able to play some games with my steam account and not all of them run with wine.


What is the best way of maintaining proxy server addresses for apt and other stuff?

I have seen a lot of posts but couldn't find a simple answer that summarizes everything.  I am new so I am still confused.  Thanks :)


I have 320 data points - each has a redshift and a turnover-frequency, and I want to fit a correlation between them (a linear fit). However, 120 of the turnover-frequency values are upper limits. As shown below the relationship is very weak:   the red points have upper limits for their turnover-frequency value. I would like to fit a straight line to this data that accounts for the upper limits. I think the tobit model in R can do this, but I'm not too sure (I'm new to R by the way); before I start with that, are there other methods in R I should consider?


I am working in Ubuntu Shell, but i want it to work for UNIX also. Here is my code:    #!/bin/bash  func() {     x=42 }  x=9 func echo $x    Why is global x changed to 42 when i changed only local variable x Is in unix different rule for variable scopes? Is there a method how to set return value from func to global variable, which can be used later in code?   Thank you!


How can I test for a player wearing specific armor?

How can I test for a player that is wearing an iron helmet named "test1" and an iron chestplate named "test2" in Minecraft Version 1.12?


Can I migrate from 19.10 to 20.10 Without re-installing?

I already reinstall, but i ask.My updates are not working. Now, i am backuping.


if(tempCard.getSuitValue() == PlayingCard.CLUBS || tempCard.getSuitValue() == PlayingCard.SPADES)   this is the line that is giving me a NullPointerException    PlayingCard redCard, blackCard, tempCard;    tempCard is declared as a varible of object PlayingCard  public PlayingCard(int newFace, int newSuit) {     faceValue = newFace;      suitValue = newSuit;  }   this is the constructor for object PlayingCard, as well as the parameters for it  public int getFaceValue() {     return faceValue; } public int getSuitValue() {     return suitValue;  }   these methods give values to the getSuitValue method used in the statement at the very top  public final static int CLUBS = 0; public final static int DIAMONDS = 1; public final static int HEARTS = 2;  public final static int SPADES = 3;   these are the constant values for the cards in the deck.    I have gone through every method and constructor that is used in the line that results in the NullPointerException.  If anyone wants to see all 4 classes, I can post them at their request.


A way for the Command+TAB app switcher to continuously cycle instead of stop at the end

Is there anyway to have the Command+TAB app switcher continuously cycle instead of stop at the end when you hold down command and tab like it did pre Mavericks?


If $k, x, y \in \mathbb{Z}$ and $k = \frac{x}{y} + \frac{y}{x}$, why is $k=2$?

I was presented with this problem: $$x,y \in \mathbb{Z}$$ $$k = \frac{x}{y} + \frac{y}{x}$$ $$\text{Prove that if } k \in \mathbb{Z}\text{, then } k = 2.$$ I began by rewriting the equation. $$k = \frac{x^2 + y^2}{xy}$$ I then reasoned that if k is an integer, then $$x^2 + y^2 = nxy$$ where $n \in \mathbb{Z}$. I continued to rewrite this to find some relation. $$x^2 - nxy + y^2 = 0$$ $$x^2 - 2xy + y^2 = (n-2)xy$$ $$(x-y)^2 = (n-2)xy$$ I figured this proved that $(n-2)xy \in \mathbb{Z}^2$, but I'm not sure how to use this fact to help me.


Does symmetry and transitivity imply reflexivity for nonempty binary relation?

I've seen a few answers to this,  and but they are not satisfying to me (possibly too advanced).   The definitions in my book are as follows:   A binary relation $\mathrel{R}$ on two sets $A$ and $B$ is a subset of $A \times B$, whose elements can be written $a \mathrel{R} b$. When we say $\mathrel{R}$ is binary relation on $A$, we mean that $R$ is a subset of $A \times A$. The relation $R$ is transitive if $a \mathrel{R} b$ and $b \mathrel{R} c$ imply $a \mathrel{R} c$, for all $a,b,c \in A$. The relation $R$ is symmetric if $a \mathrel{R} b$ implies $b \mathrel{R} a$.    Browsing Math Stack it appears those definitions are standard. Consider the following question: if a nonempty relation is symmetric and transitive, is it also reflexive?  I say yes. But in a discussion with a peer, they provide the example: consider the relation $R$ on $A$ where $A = \{0,1,2\}$ but $R = \{(0,1), (0,2), (1,0), (2,0), (2,1), (1,2)\}$. They claim this relation is transitive but I say no, because in order for it to be so we need $0 \mathrel{R} 1$ and $1 \mathrel{R} 0$ to imply $0 \mathrel{R} 0$, but clearly $(0, 0) \notin R$.  Who's right? And is it possible to generate such a nonempty relation?


How could Load average numbers from 'htop' exceed 100% CPU utlization?

I use 'htop' to monitor my web server. It's recently quite loaded and the Load average is showing something like this:  Load average: 3.10 2.56 1.63  I searched the web about these numbers and I found an article about it:  In the article, it says if I have 2 CPUs, 2.0 means 100% CPU utilization. And my VPS has two CPUs, so what does 3.1 mean? How could it exceed 100% CPU utilization? And from these numbers, does it mean I should be wary about the loading now? But the performance seems totally fine, and this is a managed VPS, the hosting company has not notified me any warning about it. During day time, Load average always show these high numbers... here is another snapshot while writing.  Load average: 3.03 2.77 1.97 Load average: 0.41 1.29 1.60 <---- 5 more minutes later  So I am wondering how much room left for this site to grow in current configurations? What kind of proactive actions I should take in advance? I don't want to wait until the server bursts. Thanks.


How to prove $\left\{ \omega|X(\omega)=Y(\omega)\right\} \in\mathcal{F}$ is measurable, if $X$ and $Y$ are measurable?

Given a probability space $(\Omega ,\mathcal{F} ,\mu)$. Let $X$ and $Y$ be $\mathcal{F}$-measurable real valued random variables.  How would one proove that $\left\{ \omega|X(\omega)=Y(\omega)\right\} \in\mathcal{F}$ is measurable.  My thoughts: Since $X$ and $Y$ are measurable, it is true, that for each $x\in\mathbb{R}:$ $\left\{ \omega|X(\omega)<x\right\} \in\mathcal{F}$ and $\left\{ \omega|Y(\omega)<x\right\} \in\mathcal{F}$.  It follows that $\left\{ \omega|X(\omega)-Y(\omega)\leq x\right\} \in\mathcal{F}$  Therefore $\left\{ -\frac{1}{n}\leq\omega|X(\omega)-Y(\omega)\leq \frac{1}{n} \right\} \in\mathcal{F}$, for $n\in\mathbb{N}$.  Therefore $0=\bigcap_{n\in\mathbb{N}}\left\{ -\frac{1}{n}\leq\omega|X(\omega)-Y(\omega)\leq \frac{1}{n} \right\} \in\mathcal{F}$.  Am working towards the correct direction? I appreciate any constructive answer!


I have a KVM switch (Trendnet TK 409) that helps me switch between my Ubuntu laptop and Linux computer. The switch use a hotkey for switching (numlock+numlock).   Unfortunatly, that only works on Windows. I found a guide on the net, and have now a script called kvm (etc/init.d)  #!/bin/bash numlockx on; sleep 1;  numlockx off; sleep 1;  numlockx on  exit 0   I have then attached a hotkey (ctrl+numlock) and this works perfectly.. But I would like to have done so that whenever I shutdown my Ubuntu computer, the script is executed so that I can continue on my windows computer.   As mentioned earlier kvm lies in etc/init.d and I have created a shortcut in rc0.d called K99kvm  But whenever I turn of my Ubuntu computer, the KVM doesnt switch to Windows computer. As I said the script itself works perfectly with hotkeys, but it doesnt work when turning the computer off.  Help would be much appreciated...  A small question aswell. Is it possible to create a hotkey in Ubuntu like numlock+numlock (2 clicks on the same button) and if yes, then how?


I am searching for the right website where I can ask Mantis bug tracker related questions? Can anybody suggest the appropriate site? It is a bug tracker application related query.  This is a specific question related with Mantis bug tracker.


I am working on a list of integers from a file. And I have to use a sorting algorithm to categorize them in descending order. I am familiar with the run time of a few sorting algorithms and I know the use of them is situational. So my question is: What would be the quickest sorting algorithm for a list of ANY size that is already 90% sorted? (in my file I have 10.000 entries but 9.500 of them are already sorted).  Thank you,


What is the sum of $\sum\limits_{n = 1}^\infty {\arctan \dfrac{2}{{{n^2}}}}$ and why?

The series  $$\sum\limits_{n = 1}^\infty  {\arctan \dfrac{2}{{{n^2}}}}$$ converges because it is asymptotic to $\dfrac{2}{n^2}$ which is convergent.  What is its sum and why?


Inserting phrase "Page" before page number in backref package

When I use the backref package within  hyperref package, for example I get this result:  Pakdemirli and Boyaci, “Comparison of direct-perturbation methods” Journal of Sound and Vibration, vol.186, p.837–845, 1995, 23 Where the number 23 at the end of bibliography is the page number where this doument is cited.  For some reasons I want to insert the phrase Page or Pages before the page number. For example:  Pakdemirli and Boyaci, “Comparison of direct-perturbation methods” Journal of Sound and Vibration, vol.186, p.837–845, 1995, Page 23  Where the whole Page 23 is hyperlink to page number 23. How can I do that?


My son is a US Citizen and he will be entering into College on coming September 2019. We (parents)are green card holder & lives in US. We have a house here in India. We want to sell it and bring the money to USA for our Son college education expenses.  We have NRI and NRO Bank accounts in India. We (parents) are an Income Tax payer. Now your advises are required as under:    What are the routes to take money from India to US and our tax liabilities   Can we gift this whole amount to my US Citizen son or what is the maximum limit of Gift amount.   What will be the tax liability on us and on my son in case of Gift   Whether we have to show it in our USA Income Tax Return or in my son Tax Return when he start to file on 2019?. What US Income Tax Laws says.   What will be the procedure to send money as Gift to my son.   Will the money will go directly from our india  Bank Act.to our USA Bank Account (or) to my son bank account.   Will there will be wire transfer from bank to bank.   Can we send money through other money sender Certified Companies also. Please advise. If there is something more on the subject to make us understand, please advise. Thanks,


Can Windows' built-in ZIP compression be scripted?

Is the ZIP compression that is built into Windows XP/Vista/2003/2008 able to be scripted at all? What executable would I have to call from a BAT/CMD file? or is it possible to do it with VBScript?  I realize that this is possible using ,  and other external applications, but I'm looking for something that requires no external applications to be installed.


Approximate Bayesian computation: where to start from?

I am about to start a project in ABC methods and I need to first of all study ABC since I know nothing about it. I spent quite a bit looking for on-line tutorials and notes but I found nothing apart for some videos. Can you please suggest me some notes or even a textbook? Not to difficult since I do not really need to understand all the math behind it. I am looking for some material that could allow me to understand the reasons behind the use of ABC methods.


Hyperref causing cleveref to not reference equation ranges properly

I'm having some trouble with referencing a range of equations. I've read several posts about how to do this using the cleveref package, but every solution posted results in my document having ??-?? shown in my pdf. I'm using TexStudio on a Mac.  I have located the source of the problem. If I have the hyperref package included, then it fails to work and produces only the ??-?? in the document. Is there some sort of fundamental incompatibility with those two packages?  My minimal working example is:  \documentclass{article} \usepackage{amsmath} \usepackage{cleveref} %\usepackage{hyperref} \numberwithin{equation}{section}  %For giving equations numbers like 1.1 ,etc \begin{document}  \begin{equation} \label{eqn:heatFluxVector} \begin{aligned} q_j &= -\lambda \frac{\partial T}{\partial x_j} + \rho \displaystyle\sum_{k=1}^{N} h_k Y_k V_{k,j}\\ & = -\lambda \frac{\partial T}{\partial x_j} - \rho \displaystyle\sum_{k=1}^{N} h_k D_k \frac{\partial Y_k}{\partial x_j} \end{aligned} \end{equation}  where $\lambda$ is the thermal conductivity. The laminar Prandtl number, $Pr_L$ is defined as:  \begin{equation} \label{eqn:laminarPrandtlNumberDefinition} Pr_{L} = \frac{C_p \mu }{\lambda}   \end{equation}  The conservation equations \crefrange{eqn:heatFluxVector}{eqn:laminarPrandtlNumberDefinition}  \end{document}


Proving products of coefficients of two polynomials are zero when the product of the polynomials is zero

Let $n \in \mathbb{N}$ and $p$ be a prime number. Let $f(x),g(x) \in \mathbb{Z}_{p^n}[x]$ such that, in $\mathbb{Z}_{p^n}[x]$, $f(x)g(x)=0$. Prove that $a_ib_j=0$ for all $i,j$, where $a_i$ and $b_j$ are the coefficients of $f(x)$ and $g(x)$.  I have the set of equations (for degree $r$ and degree $s$): $$a_rb_s=0, a_rb_{s-1}+a_{r-1}b_s=0,...,a_0b_0=0.$$ From these, how do I conclude $a_ib_j=0$ for all $i,j$? Also, I found that for $n=1$, the polynomial ring is an integral domain, so the conclusion holds. I had an idea to use induction on $n$, but do not know how to proceed.


I have two code looped snippets latter works as expected while the former throws exception. Why does  foreach work while for loop doesn't? What does it stem from?  IEnumerable<char> query = "Not what you might expect";  query = query.Where (c => c != 'a'); query = query.Where (c => c != 'e'); query = query.Where (c => c != 'i'); query = query.Where (c => c != 'o'); query = query.Where (c => c != 'u');  foreach (char c in query) Console.Write (c);  // Nt wht y mght xpct   For loop with exception  IEnumerable<char> query = "Not what you might expect"; string vowels = "aeiou";  for (int i = 0; i < vowels.Length; i++)   query = query.Where (c => c != vowels[i]);  foreach (char c in query) Console.Write (c);   foreach code,  foreach (char vowel in vowels)   query = query.Where (c => c != vowel);  foreach (char c in query) Console.Write (c);


How to break while condition when its true?

How to break the while loop, when the condition is true?  I tried using break under an if statement, but it's not working.  def proallocate():     while True:             conn = sqlite3.connect('database.db')         cur = conn.cursor()         pid = cur.execute("SELECT project_id FROM Upload WHERE status= ?", ("NULL",))         for pd in pid:             a = str(pd)             projectid = re.sub('[\(\),\{\}<>]', '', a)             url = "https://picture-us.amazon.com/colorauthor/view/"+projectid+""             print(url)             req = requests.Session()             resp = req.get(url, auth=HTTPKerberosAuth(mutual_authentication=False), verify="./amazon_dev_certs.pem")             soup = BeautifulSoup(resp.text, 'html.parser')             project_status_latest = soup.find_all('tr')[-1].get_text()             if ("Project Ready" in project_status_latest):                 proid[0] = projectid                 print(proid[0])              else:                 cur.execute("UPDATE Upload SET status = ? WHERE project_id = ?", ("Reserved", projectid))                 conn.commit()   I expect that the loop should stop when the if condition passes.


How to generate logarithms for observations in negative value

I’m doing my VAR regression with panel data on stata 12, but I face a problem with observations that are in negative value when generating logarithms. All the negative variables are missing after transformation in Logs.  Is it normal or I have to correct this! Can I have a advice? Thank you!


Recently, there was some news that said that the researchers at NASA have come across some impossible kind of space engine which does not require any fuel. I have read at a few places like ,  and . They all say that this engine seems to violate the laws of physics including conservation of momentum.  The original paper is .  Is the statement that it violates conservation of momentum true?


I'm using screen command after ssh to a public remote machine with Ubuntu 14.04 so that I could continue my sessions whenever I want. I've found that some admins are tracking my command history and they have access to my screen sessions too. I know that I can clear my bash history commands by removing .bash_history file in my home directory but couldn't find a way to clear my screen sessions' command history too.


Consider the following question:  Let $\mathbb{Q}$ be the field of all rational numbers.  Let Aut($\mathbb{Q}$) be the group of all Automorphism on $\mathbb{Q}$ (All Isomorphism from $\mathbb{Q}$ to $\mathbb{Q}$).  Show that $\mathbb{Q^{*}}$ is isomorphic to Aut($\mathbb{Q}$).  I really dont know how to prove this base on the Isomorphism theorem.  Any help will be appreciated.


Are there discontinuous Ring endomorphisms on real numbers?

It is rather straightforward to prove that the only continuous Ring homomorphism from $\mathbb{R}$ onto itself is the identity, as its restriction to rational numbers is the identity.  I wonder if that still holds if one gives up on the continuity hypothesis? In other words, are all Ring endomorphisms on $\mathbb{R}$ continuous?  My intuition would be no, because Ring axioms seem to put loose enough constraint on transcendental numbers. Yet I haven't been able to find a construction for a non-continuous endomorphism.  Technical precision: the definition of Ring homomorphism meant in this question is 1-preserving.


I want to show a custom block, only when log in has failed. So from visibility settings I have to put a PHP code that returns TRUE only when the login has failed.  But how could I "catch" that event? Do I have to use variable_get(..)? And if yes, how could I use that?with what attributes?  Thank you.


I am writing a document using REVTeX 4.2 and I have a single image file already divided in multiple parts (a, b, c, etc..). I want to reference this "subfigures" in the text. Normally I would just create phantomcaptions using the subcaption package, but this latter is not compatible with REVTeX. What should I do?  EDIT: It's important to highlight the fact that I have only a single image divided in multiple parts, but it's a single file. I want to add phantom captions that are mimicking the subfigures labels, but I don't want to use subfigure environments. In practice I have the same problem described in this question:  but the proposed solution does not work in my case, because I cannot use the subcaption package.


How to prove that $2^x,3^x,5^x\in\mathbb N$ implies $x\in\mathbb N$?

Let $x\in\mathbb R$ and suppose that $2^x,3^x$ and $5^x$ are all integers. Does it imply that $x$ is also necessarily an integer?  I read somewhere that the answer is "Yes" and a proof is known, but I haven't seen a proof and was not able to prove it myself. Could you please help me to find a proof?


Reason for audio speaker diaphragm shape

Why are the diaphragms on audio speakers usually a cone with a dome in the centre? I don't know much about acoustics but my guesses would be:   it just empirically sounds better, the design was found through trial and error an acoustically better shape (perhaps a flat panel or a larger dome) is not structurally rigid for vibration, the cone shape is rigid and relatively flat the cone/dome somehow causes interference effects that give directionality to the sound waves   Could someone shed light on the physics behind this design choice?


How to export PSD file to SVG in Photoshop CS6

I have a PSD file. I want to convert the PSD to SVG file using Photoshop CS6. Anyone able to tell me how to do this?


How do I install Komodo Edit on Ubuntu Xenial & Beaver?

I am interested in installing the latest open source release of Komodo Edit to assist me with programming on either of my Ubuntu distributions.  I viewed the official site (by ActiveState) and found a .tar download for Linux.  Can I receive some guidance for the installation on both Ubuntu 16.04 + 18.04?  Also, are there other methods that exist to install Komodo Edit other than by the usage of the .tar file?  Thanks in advance, comrades!


Why is Kullback-Leilbler divergence a better metric for measuring distance between two probability distributions than squared error?

I know that KL-divergence is a metric that is more suitable when we want to measure the distance between numbers which a probability form. However, I am still confused what is the benefit of using KL-divergence rather than squared error between probability numbers.  I appreciate if someone can explain this in simple words.


I can't seem to find a reference for the following statement:     A quotient ring of a (left) semi-simple ring (left artinian with no nonzero nilpotent ideals) is a semi-simple ring.    Does this follow from quotients of semi-simple modules being semi-simple?  A quotient ring of a left artinian ring is left artinian. So we only have to show that the quotient contains no nonzero nilpotent ideals. I'm looking for something more low-level than $\text{rad}(R/I) = \text{rad}(R) + I$, which I seem to remember to be true. Can I somehow use the characteristic that every left ideal is generated by an idempotent element?


If G is a finite Abelian group, and H is a subgroup of G, How can I prove that G/H is isomorphic to another subgroup N of G?.

If G is an abelian finite group, and H is a subgroup of G, How can I prove that G/H is isomorphic to another subgroup N of G?.


I have a field that is varchar(8), holding date values that I converted from float to varchar.    Some records have eight characters, and some have seven.  I would like to make them all the same length by adding a leading zero to the ones that have 7.    8 char example: 12162003 7 char example: 5072004 (needs a leading zero)   The query:     select birthdate_new from table_name


How do I choose between "can" and "could"?

Where can we go?   Where could we go?              Can you pass me the salt?   Could you pass me the salt?      Which sentence is more appropriate and why? What are the differences?


Does function call is replaced with function definition in javascript?

I have the below code, and it prints 42.  {   let number = 42;   function printNumber() {   console.log(number); } function log() {   let number = 54;   printNumber(); } // Prints 42 log(); }   This output brought me to wonder the function call is replaced by function definition or not?  I tried removing the "number" variable declaration in the beginning of the program to see if it reads the "number" defined inside the log() function but it returned reference error,      {  //let number = 42; function printNumber() {   console.log(number); } function log() {   let number = 54;   printNumber(); } // Uncaught ReferenceError: number is not defined log(); }   I want to understand how the function call is interpreted and how the scope is determined that if a function printNumber() is called inside another function log() then how is it not supposed to use the variable declared inside the function log() from where it is called.


Let X,Y,Z be independent, identically distributed random variables,each with density $f(x)=6x^5$ for $0\leq x\leq1$ and 0 elsewhere.I want to find the distribution and density functions of the maximum of X,Y and Z.  Answer:-I know by integrating density function, distribution function can be obtained.I computed CDF of maximum of $X,Y,Z=X^6$ and its PDF=$18*X^{17}$.  CDF of minimum of $X,Y,Z=1-(1-X^6)^3$ and its PDF is $6*X^5*3*(1-X^6)^2$


Why no compiler error for main() without a return at the end?

I'm working on a C-brain teaser:  Write the standard Hello-World program, without semi-colons.  My best answer so far is:  int main(void) {     if (printf("Hello World!\n"), exit(0), 0)     {         /* do nothing */     } }   But I don't understand why I don't get compiler error (Visual Studio):  error C4716: 'main' : must return a value   I've tried other functions with a return-type declared, but missing a return-statement, and get this compiler error.    Note that I've also tried:  int foo(void) {     if (printf("Hello World!\n"), exit(0), true)     {         /* do nothing */     } }  int main(void) {     foo(); }   And don't get a compiler error on foo.  If I remove the "exit(0)", I do get the compiler error.  Apparently the compiler has knowledge that "exit" is a special function?  This seems very odd to me.


Does Ubuntu 18.04 create entries in certain groups for the installer by default

WHat are the groups in which when installing Ubuntu 18.04 or 16.04, the installer is made a member by default. Is adm one such group? WHat about admin? What about sudo? If 18.04 has separate default groups for Server and Desktop installations, please specify.


How to disable grub menu at boot time in Ubuntu 20.04?

I have installed Ubuntu 20.04 alongside Windows. When I boot the system, it shows the grub menu for 10 seconds to choose between Ubuntu and Windows. I don't want that menu, just want to boot it up right after pressing the power button. I have looked into  thread and added GRUB_HIDDEN_TIMEOUT_QUIET=true  and even changed GRUB_TIMEOUT to 0 and then ran sudo update-grub. But it didn't work, menu is still being shown at boot time. This is my /etc/default/grub file-   # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. # For full documentation of the options in this file, see: #   info -f grub -n 'Simple configuration'  GRUB_DEFAULT=0 GRUB_TIMEOUT_STYLE=hidden GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=0 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX=""  # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"  # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console  # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' #GRUB_GFXMODE=640x480  # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true  # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true"  # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1"   How do I disable it?


Is it possible to get a star symbol in Linux?

Is it possible to get this star symbol in Linux, as shown in this screen shot?


Apache mod_proxy+mod_rewrite = "Request exceeded the limit ..." error

Good day,  I'm using Apache as a reverse proxy for my Tornado app which runs on http://localhost:8090. I want Apache to proxy everything that arrives to /api/v2 through HTTPS to http://localhost:8090. Apache is also takes care of authentication, thus I need to forward the authenticated user name to my Tornado app. Hence using mod_rewrite.  I've added the following entry to Apache config:  <Location "/api/v2">     ProxyPass http://localhost:8090      # Next four lines are to set X-Forwarded-User     RewriteEngine On     RewriteRule .* - [E=RU:%{LA-U:REMOTE_USER}]     RequestHeader set X-Forwarded-User %{RU}e      SSLRequireSSL      AuthType Basic     AuthName "My site"     AuthBasicProvider external     AuthExternal pwauth     Require valid-user      Order deny,allow     Allow from all </Location>   This works wonders, except that I see the following error in my Apache log:  Request exceeded the limit of 10 subrequest nesting levels due to probable confguration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.   I've enabled the debug log for mod rewrite and I see indeed a strange thing - it looks like the rewrite happens 10 times in loop piling the request onto itself:  172.16.0.150 - admin [29/Jan/2014:19:01:06 +0200] [sm397/sid#7f8452235588][rid#7f840c0093b8/initial] (3) [perdir /api/v2/] applying pattern '.*' to uri 'proxy:http://localhost:8090/' 172.16.0.150 - admin [29/Jan/2014:19:01:06 +0200] [sm397/sid#7f8452235588][rid#7f840c01f638/subreq] (3) [perdir /api/v2/] applying pattern '.*' to uri 'proxy:http://localhost:8090/proxy:http://localhost:8090/' 172.16.0.150 - admin [29/Jan/2014:19:01:06 +0200] [sm397/sid#7f8452235588][rid#7f840c00d6a8/subreq] (3) [perdir /api/v2/] applying pattern '.*' to uri 'proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/' 172.16.0.150 - admin [29/Jan/2014:19:01:06 +0200] [sm397/sid#7f8452235588][rid#7f840c025e08/subreq] (3) [perdir /api/v2/] applying pattern '.*' to uri 'proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/' 172.16.0.150 - admin [29/Jan/2014:19:01:06 +0200] [sm397/sid#7f8452235588][rid#7f840c029e28/subreq] (3) [perdir /api/v2/] applying pattern '.*' to uri 'proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/' 172.16.0.150 - admin [29/Jan/2014:19:01:06 +0200] [sm397/sid#7f8452235588][rid#7f840c02de48/subreq] (3) [perdir /api/v2/] applying pattern '.*' to uri 'proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/proxy:http://localhost:8090/'   Full log here:   How to fix it?  Thanks


How are and what are the sources coupled to a 3-wire RTD leads?

I can understand two or four wire connection for RTDs. But I don't get where they apply voltage or current and how they measure the resistor values for 3-wire connection:     is a page about these lead compensation techniques. In the 3 wire technique how are the resistors measured? In other words I want to see the current or voltage source connected to the three leads. Can someone illustrate how the source attached?   I'm asking how the current and voltage source are connected. The suggested duplicate doesn't show sort of thing explicitly. In short I dont get my answer when I read it. There is no current source there unlike in RTD.  Edit:  One of the answer suggested a circuit. I also found a similar one .    But what Im stuck at is why is R3 necessary instead of a short? When I vary its value in simulation neither VM2 nor VM1 change at all. What is the function of R3 here? R3 is floating doesnt pass any current


Why is this power adapter transformerless?

I saw a battery charger that converts 220V AC to 6V DC without a transformer.   Now I am wondering why many (if not all) power adapters are using a transformer, is it about efficiency or about drifting over time?  Update: This circuit is inside of this torch


Leaving a High-Deductible Health Plan (HDHP) during the year: can one still fully contribute to one's HSA?

Bob has a High-Deductible Health Plan (HDHP) and wants to maximize his contributions to his Health Savings Account (HSA). At some point during the year, Bob changes his health insurance from an HDHP to a non-HDHP. How much can Bob contribute to his HSA during this year?


Save variable and load between 2 scenes in Unity

I have variable that I need to save and load between 2 scenes.  So this is what I'm trying:  First script:  public class s1sc : MonoBehaviour  { public string playername;  public static s1sc Instance;  void Awake ()    {     if (Instance == null)     {         DontDestroyOnLoad(gameObject);         Instance = this;     }     else if (Instance != this)     {         Destroy (gameObject);     }  }   Second script:  public class s2sc : MonoBehaviour  {     public string pn;      void Start ()      {                pn = s1sc.Instance.playername;     } }   And it doesn't work fine. What is the problem??


Algebraic numbers in the interval $[0,1]$

A number $x\in\mathbb{R}$ is said to be algebraic if it is the root of a polynomial over $\mathbb{Q}$. Define $A:[0,1]\rightarrow \{0,1\}$ as  $$A(x)=1 \text { if } x \text{ is algebraic, } A(x)=0\text{ if } x \text{ is not algebraic, }$$  What is the value of $\int_{0}^{1} A(x)dx$ ?


I like the noend option from algorithmicx because it makes the layout of the algorithm closer to the python syntax my students use. But to make it even clearer, i'd like to have left threads on the left to visually empashise the indented block. Like this:


Why don't heavenly bodies attract each other stronger?

In my physics textbook, it's written that  According to the laws of gravitation force,  all masses attract each other the greater the masses, the stronger the pull the closer the masses, the stronger the pull  The pull between small masses is far too weak to measure. But the earth has such a huge mass that its gravitation force is strong enough to hold most things firmly on the ground.  The attraction between me and the earth is strong. Since the force exerted by the Earth is much more stronger than the force I exert on earth,  I'm pulled towards it. Now the attraction between heavenly bodies, let's say the earth and the moon, should be stronger than the attraction between me and the earth. At least according to the second bullet point on gravitation force. The earth should literally stick to the moon even more strongly than it will stick to me. Fat people tend to feel a stronger pull force from the earth. The attraction between the earth and the moon is not weak, nevertheless. But why isn't it as strong as it should be?


How to start remote command line session?

I use putty to login to the server via ssh. This creates a session locally; meaning if I disconnect from putty, the session is lost.  Is there any way that the session can keep running and be accessible from putty or any other client ? Or is there any other protocol or tool which can help out in this?


I have long text in a multirow cell. And the text takes more rows than the rows in the second column.  \documentclass[a4paper,12pt]{report} \usepackage{multirow} \usepackage{longtable}  \begin{document}  \begin{longtable}[H]{|p{\dimexpr0.5\linewidth-2\tabcolsep}|p{\dimexpr0.5\linewidth-2\tabcolsep}|} \caption{Title} \tabularnewline\hline \multirow{2}{\linewidth}{\centering \tiny \textbf{Long long  long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long text}} & \tiny 11 \tabularnewline \cline{2-2}  & \tiny 11 \tabularnewline \cline{1-2} \end{longtable}  \end{document}   I get this:   How can I fix it? I generate table automatically, and I do not know how many lines of text in the multirow cell takes. So I can not manually add blank lines in the second column.  Update for Bernard When I compile this code:  \documentclass[a4paper,12pt]{report} \usepackage[utf8]{inputenc}  \usepackage{multirow} \usepackage{longtable}  \usepackage{makecell}  \begin{document}  \begin{longtable}{|m{\dimexpr0.5\linewidth-2\tabcolsep\relax}|m{\dimexpr0.5\linewidth-2\tabcolsep\relax}|} \caption{Title} \tabularnewline\hline% \multirow{2}{*}{\parbox{\linewidth}%[24pt] {\centering \scriptsize \textbf{Long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long}}} & \Gape[12pt]{\scriptsize 11} \tabularnewline \cline{2-2} & \Gape[12pt]{\scriptsize 11} \tabularnewline  \cline{1-2} \end{longtable}\bigskip  {\normalsize \begin{longtable}{|m{\dimexpr0.5\linewidth-2\tabcolsep\relax}|m{\dimexpr0.5\linewidth-2\tabcolsep\relax}|} \caption{Title} \tabularnewline\hline% \multirowcell{8}{\parbox{\linewidth} {\centering \textbf{Long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long long}}} &\multirowcell{4}{11} \tabularnewline & \tabularnewline & \tabularnewline & \tabularnewline \cline{2-2} & \multirowcell{4}{11} \tabularnewline & \tabularnewline & \tabularnewline & \tabularnewline  \cline{1-2} \end{longtable} } \end{document}    I see this result:


Thermal radiation spectrum of a blackbody

Why is it that thermal radiation of a black body usually described by a spectral distribution function rather than an intensity vs frequency curve?   I have a vague explanation for this: Any measured intensity of radiation will contain a spectrum of frequencies which are impossible to separate (even with a very good spectrometer, one can only measure the intensity of an interval). So it is practically impossible to assign a particular intensity to a particular frequency.  Is my reasoning correct?


Whenever I am trying to open some sites and also sending messages in LinkedIn it showing something weird.


Compiling a Simple C lua5.0 Program, Undefined References

I try to Compile this Simple Lua Tutorial Program:  #include <stdio.h> #include <string.h> #include <lua.h> #include <lauxlib.h> #include <lualib.h>      int main (void) {       char buff[256];       int error;       lua_State *L = lua_open();   /* opens Lua */       luaopen_base(L);             /* opens the basic library */       luaopen_table(L);            /* opens the table library */       luaopen_io(L);               /* opens the I/O library */       luaopen_string(L);           /* opens the string lib. */       luaopen_math(L);             /* opens the math lib. */        while (fgets(buff, sizeof(buff), stdin) != NULL) {         error = luaL_loadbuffer(L, buff, strlen(buff), "line") ||                 lua_pcall(L, 0, 0, 0);         if (error) {           fprintf(stderr, "%s", lua_tostring(L, -1));           lua_pop(L, 1);  /* pop error message from the stack */         }       }        lua_close(L);       return 0;     }   With the Following Command:  gcc -I/usr/include/lua50 -L/usr/lib/liblua50.a -llua50 luainterpret.c   So the Headers are Linked and Library Binary should also be Linked right?  However i get the following undefined References:  /tmp/ccA3kOUt.o: In function `main': luainterpret.c:(.text+0x1b): undefined reference to `lua_open' luainterpret.c:(.text+0x31): undefined reference to `luaopen_base' luainterpret.c:(.text+0x40): undefined reference to `luaopen_table' luainterpret.c:(.text+0x4f): undefined reference to `luaopen_io' luainterpret.c:(.text+0x5e): undefined reference to `luaopen_string' luainterpret.c:(.text+0x6d): undefined reference to `luaopen_math' luainterpret.c:(.text+0xa1): undefined reference to `luaL_loadbuffer' luainterpret.c:(.text+0xc3): undefined reference to `lua_pcall' luainterpret.c:(.text+0xf6): undefined reference to `lua_tostring' luainterpret.c:(.text+0x11f): undefined reference to `lua_settop' luainterpret.c:(.text+0x152): undefined reference to `lua_close' collect2: error: ld returned 1 exit status   I checked the /usr/lib/liblua50.a file with nm and the Functions above are indeed there! Why is gcc then not able to find said Functions? Can someone tell me what im doing wrong?


KB 4480970 and or KB 4480960 breaks SMB2 connections to Windows 7 shares

It's become clear that last night's (Tues Jan 8th 2019) patches to Windows 7 broke SMB2 networking in Lanman Server.  One or both of KB 4480970 and KB 4480960 results in any OS that uses SMB2 (such as Windows XP, some Windows 7, and same generation server OS' and Mac OS X machines (certainly 10.10, 10.11 not sure about others yet)) being unable to connect to Windows 7 Pro shares.  Client machines repeatedly prompt for login despite credentials being correct.


How to create a link from static resource using aura component?

I want to create a link and download an excel file that is stored in static resource.How do i do that?


How do I link constraint data between objects?

Normally if I have a material and want to put that material on say, 50 different objects, then I would select one object with that material, and then select the rest of the objects, hit Ctrl + L, and the material data would be copied to all the objects.  I have the exact situation I described above, except that I want to copy an object constraint from one object to all the other objects. Unfortunately the Ctrl + L menu doesn't have a "Constraints" button.  How do I copy this constraint to all the other objects?


Can True Strike give me specific information about my target's defenses?

The True Strike cantrip provides:  You point a finger at a target in range. Your magic grants you a brief insight into the target's defenses. On your next turn, you gain advantage on your first attack roll against the target, provided that this spell hasn't ended.  There's another  on this site discussing the cases in which casting this spell might make sense. Implicit in these arguments seems to be the idea that the "brief insight" granted by the spell is not useful in itself. It occurred to me that such insight could be useful in itself if it granted knowledge of specific details that might be useful for higher-order tactical or strategic planning outside of just getting Advantage on the next turn. Does the brief insight granted by True Strike provide access to specific details about the target's defenses, or is the language simply an explanation of how the player gains Advantage? An example could be where I don't particularly need to gain Advantage on my next roll, but I want to know whether that bandit over there is concealing any weapons or wands underneath his cloak. If the first case is true, a DM might report,  Ok, you cast True Strike at the cloaked bandit. He has knives hidden in each of his boots, and is carrying two wands of Fireball and one of Magic Missile in the sack over his shoulder. The walking stick he is carrying conceals a three-foot double-edged sword. He is resistant to lightning damage though a spell that seems to have been cast on him, but you would need a more powerful spell than True Strike to identify the exact spell or source. If you still have concentration at the start of your next turn, you will have Advantage in attacking.


how to fix referencing a non-static method in a static context

Here is my RandomSequence class code:     import java.util.*;  public class RandomSequence implements Sequence {    private ArrayList<Double> random;     public RandomSequence()    {       random = new ArrayList<Double>();     }     public List<Double> firstTenTerms()    {       if(random.size()!=0)       {          while(random.size()>0)          {             random.remove(random.size()-1);          }       }        for(int k=0; k<10; k++)       {          random.add((int)(Math.random()*10)+1.0);       }       return random;    } }   And this is my driver class:     import java.io.;     import java.util.;  public class SequenceMain {    public static void main(String[] args) throws Exception    {       File f = new File("sequence1.txt");       Scanner scan = new Scanner(f);       System.out.println("I'm going to generate a random \"sequence\" and sort it. Here're the first 10 terms of sequence.");       System.out.println(RandomSequence.firstTenTerms());     }     public void ascendingSort(List<Double> alist)     {       Collections.sort(alist);     }  }   When I run the driver class, I keep on getting these error messages:  SequenceMain.java:13: error: non-static method firstTenTerms() cannot be referenced from a static context       System.out.println(RandomSequence.firstTenTerms()); SequenceMain.java:18: error: non-static method ascendingSort(List<Double>) cannot be referenced from a static context   ascendingSort(alist);   There already seems to be quite a few questions related to the non-static methods and static context etc, and I've gone through some of those posts, but frankly, I'm now more confused than before.   Update: Thank you for those who gave me feedback on line 13, but how can I fix 18? I feel that it's a bit different.


Sharepoint online, enable rich text editor for a custom field

I've an APP with an input text item. It's possible to activate the rich text editor of sharepoint (365) to edit this field? And If i want to do the same thing into a grid?  Thanks!!


As a sysadmin I sometimes face situations, where a program behaves abnormally, while not creating errors at all or creating nonsense error-messages.  In the past - before java came in - there were two counter-measures:   If nothing else helps - RTFM ;-) If even 1. does not help - trace the system-calls and see what is happening   I usually use strace -f for this task with Linux (other OS have similar trace-tools). Now while this usually works well for any old-fashioned program, the trace gets very fuzzy when doing the same on a java-process. There are so many system-calls seemingly unrelated to any real action, that it is terrible to search through such a dump.  Are there better ways to do that (if the source-code is not available)?


Is it possible to remotely debug a process started outside VB6?  The application is a VB6 application with quite a few dll/ocx resources. I am attempting to setup a ClickOnce deployment, using Registration-Free COM, of the VB6 app but have been getting errors when it executes.  My understanding of the way that VB6 redirects COM registerations will probably mean that this is not possible but I thought someone might have a better idea.


Refreshing SFDC page from VF frame: CORS issue

I have a VisualForce page inside a standard SFDC Page Layout.  For UX reasons, we want to be able to refresh the outer (parent) page when something is clicked on the VF page.  When we try and do this using parent.location.reload(), we get the CORS JS error:  Uncaught SecurityError: Blocked a frame with origin "" from accessing a frame with origin "". Protocols, domains, and ports must match.  So we went to CORS whitelist, and added https://*.visual.force.com as an entry.  But this still did not fix the issue.  Anyone else come across this?


Select from one table if no records found in another

I have two tables:  t1 ------------ id user   t2 ------------ user_id item   I need to select from t1 if no matching records found in t2  SELECT *  FROM t1 LEFT JOIN t2 ON (t1.id = t2.user_id) WHERE ???   Kinda stuck...


FTP FileZilla connection issue “Connection refused by server”

I'm trying to set up file transfer via FileZilla and it doesn't seem to matter what details I put in, I always get the following error:     Status: Connection attempt failed with "ECONNREFUSED - Connection   refused by server". Error: Could not connect to server   My Dad has tried on his computer (with FileZilla on Windows) and it connects and everything is fine.. When I try on mine with all the same details that he put in, it comes up with that error.  I read that a firewall might be blocking it so I double checked and my firewall through system preferences and it is off.  Anybody know why this might be???  Additional info:  Macbook Pro running OS X El Capitan version 10.11.6  FileZilla version 3.23.0.2


I am curious as to the possibility that in the future Stack Overflow makes money out of my volunteer work in the present.  What if in the future information about a specific issue is very hard to get outside Stack Overflow ? Is it possible that the owners of this website start charging users to view content? my content?


What is the correct XPath for choosing attributes that contain "foo"?

Given this XML, what XPath returns all elements whose prop attribute contains Foo (the first three nodes):  <bla>         </bla>


A strange NullPointerException : Fatal Exception: java.lang.NullPointerException: Attempt to read from field 'xx' on a null object reference

This is a strange NullPointerException because my code is like this:  class MyTool {     private MyObject myField;      public void doSomething() {         myField //Fatal Exception: java.lang.NullPointerException: Attempt to read from field 'myField' on a null object reference     } }   The crash is reported from our crash logs and I can't reproduce it.  I feel it strange because why it does not happen when invoking the doSomething() method but on a field reading inside.  Updated!  I know what is NullPointerException is and this one is different!  The Tool is used in Android fragment and is used for loading an url:  public class PreloadUtils {      @BindView(R.id.preload_webview)     WebView webView;      public PreloadUtils(View view) {         ButterKnife.bind(this, view);         webView.getSettings().setJavaScriptEnabled(true);     }      public void preload() {         webView.loadUrl("my-url");     }      public void destroy() {         if (webView != null) {             webView.destroy();         }     } }   then in my Fragment's onCreateView():  preloadUtils = new PreloadUtils(layout);// the layout is the Fragment's layout, a WebView(id=preload_webview)is added in the layout file, and preloadUtils is a member field preloadUtils.preload()   and in my Fragment's onDestroyView():  @Override public void onDestroyView() {     preloadUtils.destroy();     super.onDestroyView(); }   These codes are working well normally.  I got the crashes from my crash report console:  Fatal Exception: java.lang.NullPointerException: Attempt to read from  field 'android.webkit.WebView com.xx.yy.zz.PreloadUtils.webView' on a  null object reference at PreloadUtils.destroy   The NullPointerException happens when reading field, not when invoking the destroy() method!   I can not reproduce the crash!


Do you need a comma before a subordinating conjunction (like if)?

Are both of the following sentences correct?  a: You can call me, if you need me.  OR  b: You can call if you need me.  Note that in a:, the comma is placed before the "if" and is not present in case b.  From this link, I gather that it isn't necessary because it's a short sentence:   But can someone point out an "official" source on this usage?


Prove this function is differentiable and find it's derivative. $$ S(x)= \begin{cases} \frac{\sin x}{x} & x\neq0\\ 1              & x=0 \end{cases} $$ The derivative in $\mathbb{R}-\{0\}$ is : $\frac{x\cos x-\sin x}{x^2}$, but I don't know how to find the derivative at $x=0$


Standard Visitor visa refusal (Deception, V3.6(b)) and procedure for reapplying

My mother acquired a criminal record in UK in 2010 when she was given a conditional discharge for 12 months and charged £85. This time while applying the on-line applications for her, I accidentally missed the criminal records column and replied "NO". The visa was refused with appeal and administrative review not allowed.  Can someone please suggest my next course of action for reapplying for a visa  It is an extremely urgent family matter, and I want the visa as early as possible. While researching I found in a blog some mention of a forwarding letter while reapplying.  Can someone please enlighten me on the entire issue?


Interpreting Granger causality test's results

I'm trying to educate myself on Granger Causality. I've read the posts on this site and several good articles online.  I also came across a very helpful tool, the , that allows you to enter your time series and calculate the Granger Stats.  Below, is the output from the sample data included on the site. I have also taken a crack at interpreting the results.   My Questions:     Is my interpretation directionally correct?   What key insights have I overlooked?   Also what is the meaning and interpretation of the CCF charts?  (I'm assuming CCF is cross correlation.)     Here are the results and plots that I have interpreted:  Summary of computational transaction Raw Input   view raw input (R code) Raw Output  view raw output of R engine Computing time  2 seconds R Server    'Herman Ole Andreas Wold' @ wold.wessa.net  Granger Causality Test: Y = f(X) Model   Res.DF  Diff. DF    F   p-value Complete model  356          Reduced model   357 -1  17.9144959720894    2.94360540545316e-05  Granger Causality Test: X = f(Y) Model   Res.DF  Diff. DF    F   p-value Complete model  356          Reduced model   357 -1  0.0929541667364279  0.760632773377753       My interpretation:    Test was based upon 357 data points and was performed with a lag value of 1 The p-value of 0.0000294 means I can reject the null hypothesis that x does not cause y for the Y = f(x). The p-value of .76 allows me to accept the null for X = f(Y) The fact that first hypothesis was rejected and second accepted is a good thing  I'm a little rusty on my F-test so I don't really have anything to say on this for now. I'm also not sure how to interpret the CCF graph.   I really appreciate it if any of you who are well versed with Granger-causality could let me know if I'm interpeting this correctly and also fill in some of the blanks.   Thanks for your help.


Combinational meaning of $\sum\limits_{k=r}^{n} {k \choose r }={{n+1} \choose r+1}$

What's the combinational interpretation of the identity $\sum\limits_{k=r}^{n} {k \choose r }={{n+1} \choose r+1}$?


'Low Disk Space' (and Disk Usage Analyzer) vs Disks utility

I have posted  here before.  A similar thing happened this morning. I received a Low Disk Space warning      The volume "InternalHDD" has only 873.8 MB disk space remaining   I clicked the button "Examine...", and up comes Disk Usage Analyzer which (unfortunately) says      Could not scan folder "/mnt/InternalHDD" or some of the folders it   contains   So I start the Disks utility to have a look, and the Disks utility reports that my disk "InternalHDD" has 52 GB free.  There's no immediate problem, because I was able to free up 256GB immediately on my "InternalHDD".  What I want to know is:   Why does this happen? What is being measured to give the 873.8 MB free disk space number? What is being measured to give the 52 GB free disk space number? Why are these numbers different, when they are supposedly for the exact same disk at the same moment?   Here are screenshots of each of these:


Meat is thawing in failing freezer. Can it be refrozen?

Freezer is failing and meat is thawing. Still refrigerator temp cold. Is it safe to refreeze?


Can I mute notifications on a specific question?

I recently asked my  on Code Golf. In doing so, I was not prepared for the deluge of notifications.  In just one day, I have received over 25 notifications from that single question. Due to the competitive nature of Code Golf, I would prefer to wait and give others more time to answer before looking them over.  Can an option be provided to unsubscribe or temporarily mute notifications from a specific question?


How does Python adds a scalar in a matrix?

I have a 3x3 zero matrix a = [ [0,0,0], [0,0,0], [0,0,0] ]  Suppose I want to add 1 to the first element of the matrix. I use : a[0][0] += 1  I thought it would add 1 to the a[0][0]th element and the matrix a would be : a = [ [1,0,0], [0,0,0], [0,0,0] ]  But , in reality the matrix is now : a = [ [1,0,0], [1,0,0], [1,0,0] ]  Why is 1 added to a[0][1] and a[0][2] also ? Full snippet : a = [[0] * 3] * 3  a[0][0] += 1 print(a)


What is the function of 'a-' in the phrase 'cocks a-crow'

This is a beginning of W.B.Yeats's poem Under Ben Bulben:     Swear by what the Sages spoke   Round the Mareotic Lake   That the Witch of Atlas knew,   Spoke and set the cocks a-crow.   What is the function of a- in the phrase cocks a-crow? What is the general structure and meaning? I think this function is different from what explained in this     I guess here a- applied in the meaning of of. The Oxford dictionary indicates this meaning and brings the example of anew.


This might be a silly question as it just doesn't make sense to me - but could we have a dimension lower than one? Could we have a 0th dimension? Could we have a -1th dimension?  Are we supporting the 2nd dimension, 1st dimensions existence by being part of the higher multiverse?  Finally, can fields inside our dimension (higgs field) interact with other dimensions? I am sure certain that we think gravity is a force interconnecting this "multiverse" together, if it even exists, but can our own particles and matter interact with dimensions completely different to us? Are we affecting other dimensions in this so called "multiverse"?  Even though this query makes absolutely no sense to me - I'm sure the second part of the question can be answered.


I want to register and enqueue RequireJS before jQuery so that jQuery finds out RequireJS and register itself as the AMD module. How to achieve this?


Proving $(C_b(X,Y),d_{\infty})$ is complete if $(Y,d_y)$ is complete

Let $(X,d_X)$ and $(Y,d_Y)$ be metric spaces. We say a function $f: X \rightarrow Y$ is bounded if $f(X)$ is a bounded set of $Y$. Consider   $$C_b(X,Y) = \left\{f: X \rightarrow Y \mid f \ \text{is continuous and bounded} \right\} $$ with the metric $d_{\infty}(f,g) =  \sup\left\{d_y(f(x),g(x)) \mid x \in X \right\}. $ Prove that   $(C_b(X,Y),d_{\infty})$ is complete if $(Y,d_Y)$ is complete.   Attempt: In my course, we already proved that if $(X,d_X)$ is a metric space, then $$C_b(X, \mathbb{R}) = \left\{f: X \rightarrow \mathbb{R} \mid f \ \text{is continuous and bounded} \right\}$$ is a complete space for the $d_{\infty}(f,g)= \sup\left\{|f(x) - g(x)| \mid x \in X \right\}$ metric. I want to use this result now. I know that if $Y$ is a complete metric space, and $X$ is a bounded subspace of $Y$, then $X$ is also complete.   So in this case I said $C_b(X,Y)$ is a subspace of the complete space $(C_b(X,\mathbb{R}),d_{\infty})$. So I need to prove that $C_b(X,Y)$ is closed in $C_b(X, \mathbb{R})$ ? Then let $f_n \in C_b(X,Y)$ be a convergent sequence. Denote the limit by $f \in C_b(X,\mathbb{R})$. I need to prove that $f \in C_b(X,Y)$.   I'm not sure how to prove the continuity of $f$. Also, I haven't used the fact yet that $(Y,d_Y)$ is complete so I'm not sure if this is the right direction. Any help is appreciated.


I am deploying my code to production and i am getting the below error  Failure Message: "System.LimitException: Too many SOQL queries: 101", Failure Stack Trace:   My trigger  trigger OpportunityTrigger on Opportunity (after delete, after insert, after undelete,  after update, before delete, before insert, before update) {      if(Trigger.isAfter && Trigger.isInsert){         {         EncryptURl.insertOpp(Trigger.new,Trigger.newMap.keySet());         } }   and my trigger class is  public static void insertOpp(Opportunity[] o,Set<id> newMapKeySet) {      list<Opportunity> oppsToUpdate =[select id,Encrypted_URL__c from Opportunity where id  IN :newMapKeySet];     for(Opportunity op:oppsToUpdate){         if(op.id != null){             string oppid=op.id;             Blob dataLead = Blob.valueOf(oppid);             String b64Data = EncodingUtil.base64Encode(dataLead);             string oppURL =Label.PWV_FavoriteURL+'oId='+b64Data;             op.Encrypted_URL__c =oppURL;         }       }     try{     update oppsToUpdate;     }catch(exception e){             system.debug('DMl exception'+e);      }  }   Can i know where i am going wrong ....


Is there a place on the internet where I could find actual Star Trek episode scripts?

Through the years I have purchased a few Star Trek scripts. I even have a DS9 script a buddy of mine mistakenly took off set and dazzled me with at Christmas years ago. As neat as those are to own, they are impossible to search. Is there a place on the internet where the Star Trek show or movie scripts can be obtained in digital format?  (Sometimes I remember a quote and would love to find it. From time to time the internet delivers. Occasionally it does not. I want to have a resource to find quotes as I think of them.)


zsh .zprofile / .zlogin not being sourced on gdm login?

I have noticed that ~/.zprofile and ~/.zlogin are only loaded (in my computer) when I use a login shell, but when I login with gdm, they are not run; ~/.profile is ran instead. Is this normal?


Conclusively stop wake timers from waking Windows 10 desktop

How do you stop a Windows 10 Desktop waking up from the sleeping/hibernated power state without user intervention?  For lots of users this won't be an issue but, if you sleep in the same room as your PC, then having your machine wake up at 3:30AM to download updates is irritating.


Do Category Theory and/or Quantum Logic add value in physics?

I know they have their adherents, but do more or less esoteric branches of mathematics such as Category Theory and/or Quantum Logic provide powerful tools for new theory development or are they just occasionally-useful presentational frameworks?  More particularly, is it worth investing the time to study these formalisms?


Is $O_n$ isomorphic to $SO_n \times \{\pm I\}$?

This question is taken directly from Artin's "Algebra", on page 150:  Is $O_{n}$ isomorphic to the product group of $SO_{n} \times \{\pm1\}$?  Here, $O_{n}$ is defined as the group of orthogonal matrices, $SO_{n}$ is the special group of orthogonal matrices (i.e. orthogonal matrices which have determinant or $1$ or $-1$).


I'm running:  zip -r /var/www/html/example.com/temp/test.zip /var/www/html/example.com/files_to_zip/   which works but gives me the full directory structure of /var. I saw the -j flag which removes these directories, but it also removes the directories in files_to_zip. Is there a way to recursively build my zip from the files_to_zip directory?  I'm running Amazon Linux 2 and my zip is using Zip 3.0.   So the previously described behaviors are demonstrated with:  exec('zip -r ' . $temp_dir . 'test.zip ' . $zip_dir . '/'); exec('zip -rj ' . $temp_dir . 'test.zip ' . $zip_dir . '/');   I've modified my code per the provide dup and answer to:  exec('(cd ' . $zip_dir . '; zip -r ' . $temp_dir . 'test.zip ' . $zip_dir . '/)');  exec('cd ' . $zip_dir . '; zip -r ' . $temp_dir . 'test.zip ' . $zip_dir . '/');   per  I also tried:  exec('(cd ' . $zip_dir . ' && zip -r ' . $temp_dir . 'test.zip ' . $zip_dir . '/)'); exec('cd ' . $zip_dir . ' && zip -r ' . $temp_dir . 'test.zip ' . $zip_dir . '/');   I've also tried a PHP solution to this:  chdir($zip_dir); exec('pwd', $result); die(print_r($result));   which returned the results of $zip_dir.  The behavior is the same, my zip has the full path from /var. After every code execution the zip size increases by 1 byte though.


Why the command \LaTeX (and I think also \TeX, \XeLaTeX, etc.) is missing of a blank space? I add my MWE: \documentclass[a4paper,12pt]{article} \begin{document} Far far away, behind the word mountains \LaTeX far from the countries Vokalia and Consonantia, there live the blind texts.  \end{document}


Is there some sort of classification of all minimal non-cyclic groups?

Does there exist some sort of classification of all minimal non-cyclic groups (non-cyclic groups, such that all their proper subgroups are cyclic)  I know the following classes of such groups:  1) $C_p × C_p$, where $p$ is a prime  2) $Q_8$  3) $\langle a,b | a^p = b^{q^m} = 1, b^{−1}ab = a^{r}\rangle$, where $p$ and $q$ are distinct primes and $r ≡ 1 \pmod q$, $r^q ≡1 \pmod p$.  (These three classes completely cover the case, when our group is finite: )  4)$C_{p^{\infty}}$, where $p$ is a prime  5)$(\{ \frac{n}{p^m}| m, n \in \mathbb{Z} \}, +)$, where $p$ is a prime  (These two classes completely cover the case, when our group is infinite abelian: )  6)Infinite non-abelian groups, such that all their nontrivial proper subgroups are isomorphic to $C_{p}$ for a fixed prime $p$ (Tarski monster groups)  7)Infinite non-abelian groups, such that all their nontrivial proper subgroups are isomorphic to $C_{\infty}$ ().  However, I do not know, whether there exists anything, that does not fall into these classes. I only know, that if such groups exist, they have to be infinite non-abelian.


Some properties of Yosida-Moreau transform

Let $f(x)$ be a continuous function on $\mathbb{R}^n$, $f(x) \geqslant 0$ for any $x$. Define $$    f_{\alpha}(x) = \inf\limits_{y}\left( f(y) +\frac{|x-y|^2}{2\alpha} \right) $$ where $\alpha > 0$. How to show that $f_{\alpha}(x)$ is locally Lipschitz continuous and $f_{\alpha} \to f$ when $\alpha \to 0+0$ uniformly  on any compact $K$ in $\mathbb{R}^n$?


Java: Using a for-loop to fill in an array with random integers within a specific range

Criticism is welcome! I'm learning and wish to be corrected so that I   may learn!   How would I go about using a for-loop to generate a random values to fill an array within the range of something like 1 to 50.   I have it set up to fill an array with however many numbers the user wishes for it to fill. I'm currently just playing around with arrays trying to understand how to use them in different ways. I know I'll have a test coming up where I'll have to do something similar and would like to have mastered it.   This is what I have so far... but I'd like to fill it with random integers in a range (any range), but for the sake of giving a range for learning purposes lets just go with 1-50.  import java.util.Scanner; import java.util.Random;  {public static void main(String [] args)    {      Scanner MyScan = new Scanner(System.in);      int Number;      System.out.println("How many integers do you want in your array?");      Number = MyScan.nextInt();      int[] MyArray = new int[Number];      }//end main }//end class


How do Ubuntu flavors compare regarding resource consumption and performance?

Minimum requirements statistics do not provide enough accurate info to new and prospective users trying to determine a suitable flavor for their machine. People need to know if an OS will run smoothly on their hardware. We need the ability to easily compare Ubuntu flavors in terms of resource usage and management.   Points of interest include:  Performance   responsiveness under load (e.g. Firefox open with 10 tabs) menu/dash speed    Resource usage   memory usage hard drive usage 3D graphics requirements   This data could be depicted using bar graphs and with different versions (13.04, 13.10, 14.04, etc) in separate graphs but most important are the latest versions.  How do they compare under standard use case scenarios such as using Firefox, LibreOffice, or watching full screen flash videos or Netflix? Will my machine be snappy and responsive running Ubuntu or am I better off with Lubuntu or Xubuntu? What are the minimum system requirements for a reasonable speedy and responsive system? Official minimum hardware requirements specifications do not provide this info.


How do I get the height of a figure in LaTeX

I have some LaTeX code  \begin{figure}     ABC     \caption{def} \end{figure}   And I would like to be able to find its height in a pdf output. The method outlined  doesn't work, yielding the error:  ! LaTeX Error: Not in outer par mode.   I considered the idea of using \write18 and somehow measuring the size of the figure by itself using pixel-grabbing tricks, but if the document had a globally changed caption size, that would mess things up.  I was wondering if there was a valid way to do this.


How do I say whether or not a number was pronounced like a telephone number (or zip code). Are there words for this?

501 can be pronounced 'five hundred one' or 'five zero one'. How do I tell someone how it was pronounced without saying the number. The best I've come up with is 'normal style' vs 'zip code style'. How about some proper terms? What about the distinction between 'five zero one' style and 'five oh one' style? I know this bit is a long shot but what the heck.


Ubuntu 12.04 changing permissions External Hard Drive from Terminal

I am attempting to rescue files from a broken system via the root terminal of the recovery console.  I have a seagate 2TB external hard drive.  Output of sudo fdisk -l:  /dev/sdb1 is the device boot HPFS/NTFS/exFAT is the system   Everytime I try to copy files to the hard drive via:  sudo cp [file] /media/Expansion\ Drive   I get:  cp: cannot create regular file `/media/Expansion Drive/[file]' : Read only file system   I have tried:  sudo chmod -R 775 /media/Expansion\ Drive sudo chmod -R 777 /media/Expansion\ Drive   and  sudo chmod a+rwx -R /media/Expansion\ Drive   and for each command, the output is:  chmod:  changing permissions of `/media/Expasion Drive': Read-only file system   So I'm at a loss.  I've tried searching for more help, but the majority of solutions that I have found involve using nautilus of some other GUI and I am unable to access those resources because I can only access from the recovery console root shell  Please help! The crash seemed spontaneous and I was unable to back up my current project... Any help would be greatly appreciated.


change ubuntu to be second OS (after Windows 10) in boot menu

I installed Ubuntu via DVD onto a Windows 10 laptop.  During boot, Ubuntu is the default option, and Windows 10 is a menu option.  How do I make Windows 10 the default boot option please?


Copy/paste from the PhD thesis into my future publication

I am writing my PhD thesis right now. I do not have any published paper by now, but a manuscript which will be published probably after or at the same time of my defense. Can I just Copy/ Paste some parts (discussion for example) from my manuscript in thesis? Would be any problem afterwards for publishing this manuscript? In other words, I am afraid if the reviewers of paper say that “you cannot Copy and Paste the discussion of your thesis, without rephrasing it”.


Show a polynomial is irreducible in $\Bbb C[x,y]$

If I have a polynomial with more than one variable, for example $\Bbb C[x,y]$ (with $\Bbb C$ the complex numbers), how can Ii see whether it is irreducible or not? For example, if I have $x^2-y^2-1$, what can I do to know whether it is irreducible or not? In this example I tried to used Eisenstein's theorem in $\Bbb C[x][z]$, but I don't know how to do it. Thanks!


I am trying to give a non-algebraic proof for this equality:  $$\dbinom{a}{b}\dbinom{b}{c}=\dbinom{a}{a-c}\dbinom{a-c}{a-b}$$  So far, I could only use the identity $\dbinom{x}{y}=\dbinom{x}{x-y}$.  What I got is $\dbinom{a}{a-c}\dbinom{a-c}{a-b}=\dbinom{a}{c}\dbinom{a-c}{b-c}$. But I don't think I have made any progress from there. It seems reasonable if we think about the identity, but I just find it difficult to give a proper proof for it.  Thanks for the help.


How to refer to United States of America?

My sentence is:     ATC experienced rapid growth between 1880 to 1911. In 1890, their five main competitors joined their consortium and by 1910, the American Tobacco Company had absorbed 250 companies, producing 80% of the tobacco products in the United States of America and had grown its equity from $25 million to $316 million.    I am conflicted on how to refer to USA (Bold part)  Is it:  in the United States of America  or  in United States of America  Also, sneaky second question if you guys don't mind :)  Do you think my sentence is too long?


Quick question to proof of bijection in measure

Hi am am taking a course in measure- and integral theory. Here I have been asked to prove that there exists a bijection $ f : [0,1] \rightarrow \mathbb{R} $. Would it suffice to find a function that is a bijection and prove injectivity and surjectivity or would this be not be the point of such an exercise?  Function found:  $ g(x)=\ln\left(\frac{1}{x}-1\right) $  $ g^{-1}(x)=\frac {1}{1+e^x} $


I have a cron job that runs every minute on an Ubuntu 12.04 box  $sudo crontab -e * * * * * mylogin /pathto/file.sh > /log/filelog   If I run file.sh, the bash script does some stuff and echos out runs:  $ ./file.sh  runs   If I check the log of cron tab it shows that the job is running:  Jul 10 12:41:01 localhost CRON[1811]: (root) CMD (mylogin /pathto/file.sh > /log/filelog) Jul 10 12:41:01 localhost CRON[1810]: (CRON) info (No MTA installed, discarding output) Jul 10 12:42:01 localhost CRON[1813]: (root) CMD (mylogin /pathto/file.sh > /log/filelog)   However, the script is not running. It is not doing it's work and not echoing runs to /log/filelog.  $cat /log/filelog  #shows nothing   What other steps can I take to debug this problem?


Can you please correct this sentence. I am bit confused about this sentence. I think its not a correct sentence.


Derivatives: enter "evaluated at" vertical bar with multiple values as subscripts

Sorry for the long title, but how do I enter evaluated at (for a derivative), with multiple valuation criteria at the bottom of the the big | line?  Thanks!


In Python, x is y returns true if the two sides evaluate to the same object; that is, it checks pointer equality. Now I tried something like this:    >>>a = 2   >>>a is 2   True     However..    >>>a = 9203409249024   >>>a is 9203409249024   False   Why this difference in behavior?