Variable is setting itself to value of another variable

PS: This question is different than others because I need to know exactly what code to write in order to prevent the variable from changing.  I have this example of code to demonstrate my problem:  float[][] one = {{0}}; float[][] two = one; System.out.println(two[0][0]); one[0][0] ++; System.out.println(two[0][0]);  int three = 0; int four = three; System.out.println(four); three ++; System.out.println(four);   The output is:  0.0 1.0 0 0   For some reason, when I change float[][] 'one', 'two' automatically changes as well. However, when I performed the same task but for a different data type int, then the code works as intended.  What is causing this variable to drag the other one with it?  Why doesn't it happen for the int type?  How do I fix it?


Is the variable inside a block still visible outside the block?

I am new to python and suddenly was surprised seeing that a variable is still visible outside the block in which it's declared and assigned. The code is below:  with open('data.txt', 'r') as file:     text = file.readlines()     # and when do I close the file?  for i in range(len(text)):  # still can access the text even after the block.     print(text[i])   How is this possible for the variable to be seen from outside the block? Thanks in advance.


How to decide whether to replace or repair?

My car has apparently has a blown head gasket...  The options at this point are basically:   put $5k into an 8 year old car with 120k mi that is otherwise in good shape (with a 2 year warranty on the new engine), or spend $15k on a newer (used) car -- which will essentially be an unknown quantity in terms of what kinds of problems it may have.   How do you decide which is the better course? (In my case, I've got a trustworthy mechanic to do the work.)  Edit: In the end, we decided to replace it. Sold the car to the mechanic, who tried to revive it, failed to do so, and is now stripping it for parts....  Thanks to all for the helpful advice.


Is it possible to construct an entire function that grows faster than any given continuous function.

Assume that $f$ is a given real-valued continuous function over $\mathbb{R}$. How to construct an entire function $F$ such that $F(z)$ is real-valued when $z\in \mathbb{R}$ and there exists a real number $a$ such that $f(z)<F(z)$ for all $z>a,z\in \mathbb{R}$.


To show an entire function is constant. (only with imaginary bound)

Assume $|f(z)|\leq 1/|y|$ for all $z\in\mathbb{C}$. Here $f$ is entire and we express $z=x+iy$. Then is $f$ constant ?


Prove that $\frac4{abcd} \geq \frac a b + \frac bc + \frac cd +\frac d a$

Let $a, b, c$ and $d$ be positive real numbers such that $a+b+c+d = 4$. Prove that $$\frac4{abcd} \geq \frac a b + \frac bc + \frac cd +\frac d a .$$   How can I approach this using only the ? Are there any other methods that do not involve the AM-GM inequality?


What are the steps to install Balena Etcher to the 16.04 Launcher toolbar?

Ubuntu 16.04: Balena Etcher .zip file returns a .AppImage file.  What are the steps to install the .AppImage file so that it can be summoned from the launcher toolbar?  Solutions that utilize native 16.04 functionality are sought.  Update:  failure:   sudo apt-key adv --keyserver hkps://keyserver.ubuntu.com:443 --recv-keys 379CE192D401AB61  Executing: /tmp/tmp.RuUWuAhwMh/gpg.1.sh --keyserver hkps://keyserver.ubuntu.com:443 --recv-keys 379CE192D401AB61 gpg: requesting key D401AB61 from hkps server keyserver.ubuntu.com gpgkeys: HTTP fetch error 1: unsupported protocol gpg: no valid OpenPGP data found. gpg: Total number processed: 0 gpg: keyserver communications error: ? gpg: keyserver communications error: g10err=127 gpg: keyserver receive failed: g10err=127   Unable to find package:  sudo apt-get install balena-etcher-electron      Reading package lists...    Done Building dependency tree   Reading state information...    Done E: Unable to locate package balena-etcher-electron


We know that  $2^2=2+2$  $3^2=3+3+3$  Similarly  $x^2=x+x+...$ ( upto $x$ times)  Now I want to differentiate both side with respect to $x$  This gives $2x=1+1+1+.....$ ( upto $x$ times)  $2x=x$  Cancelling $x$ I have   $2=1$  Which should be false. Where am I going wrong? Please tell. The proof has to be wrong somewhere.


trigger existing event on appended elements

I'm trying to get both blur and keypress(13) to do the same thing on an element that has been appended. An obvious use for trigger(), right? Not working. I'm hoping I'm just being stupid and missing something obvious.    $(document).ready (function() {   $("#btn").click (function() {     $("#this-ul").append ("
<input id='input1' type='text'>

<input type='text' id='input2'>
");     $("#input1").focus();   });   $("#this-ul").on ("blur", "#input1", function() {     $("#input2").val ("blurred");   });   $("#this-ul").on ("keypress", "#input1", function (e) {     if (e.which == 13) {       // Want to trigger $("#this-ul").on ("blur"...) as above     }   }); });   <button id="btn" type="button">Click</button>


Does Ubuntu V12.04.2 work on a system that normally run Windows 7 64bit with an Intel processor?

Can't get ubuntu-12.04.2-desktop-i386. I get the message "No DEFAULT or UI directive found! boot:" After the failure on the WIN7 machine I took the exact same CD and used it on an older WIN XP 32 bit machine. The disk worked prefectly on the 32 bit machine.


Rigid motion on $\mathbb{R}^2$ which fixes the origin is linear

Let $V=\mathbb{R}^2$ be an inner product space with the standard inner product, and let $T$ be a rigid motion of $V$. Suppose $T(0)=0$, prove that $T$ is linear.  (A rigid motion of an inner product space is a function (not necessarily linear) $f:V \to V$, such that $||f\alpha-f\beta||=||\alpha-\beta||$.)  It is obvious that $T$ preserves the inner product (T is unitary), but I don't know how to prove that $T$ is linear. Thanks in advance


Ubuntu 18.04 problem partitioning with GParted

I'm trying to partition my sda2. Right now I have:  sda1: fat32: efi  sda2: lvm2 pv: ubuntu-vg  But GParted says my sd2 has 0b unused space. I used du -sh /*; but I have nothing that consumes all the spaces.  Anyone has an idea? Thx


Define $a_n$ is real sequence which satisfies   $$a_1=1, \quad a_{n+1}=\sin(a_n)$$  Find  $$\lim_{n\to\infty} \sqrt{n}a_n$$  I just know $$\lim_{n\to\infty} a_n = 0$$  but I don't know what should I do.  I'm interested in two solutions (using Stolz-cesaro, without using stolz-cesaro).


Why does HDD activity slow the whole System down (on Windows 7)?

If I copy a large amount of data from on drive to another (physical) drive my whole system is running slow.  I am using Windows 7 64bit version on an Intel Core 2 Duo 3 GHz.  This is the situation:   Very fast copying between two SATA disks.  Resource Monitor shows 80MB/s read, 70MB/s writes and 150MB/s total The total CPU load is about 3% There is plenty (>2GB) of free physical RAM left All partitions have enough (>10gb, >10%) of free space left and show low fragmentation Anti-Virus software is not active   This is the problem: No matter what I want to do while copying, it takes forever. Even tasks that do not need a lot of disk access (as they should work from RAM only), are extremely slow. The moment I stop the copying process, all the unfinished tasks finish at once. For example trying to open a new browser windows or explorer window will not work. If the copying is stopped 5 explorer windows popup at once.  My question is: why? What resource is exhausted, if CPU and memory are idle? And what part of my computer hardware I need to upgrade to get better behavior? Also read Psycogeek's comment for further questions in this direction.  If your answer is, that everything needs HDD Access, which is blocked by such an activity, then my question is: Is there a way to copy something on your system without rendering it unusable until its done? (which can be hours, if >500g have to be copied).


Short Story ID: Beginning of telepathic humans

I believe I read a short story in the 50's about the beginning of telepathy in humans. The enemies were breaking into the location as the couple telepathically married themselves just before being killed.  Anyone have a clue to this written missive?


Why is my iPhone 4S showing so much "Other" data in iOS 7?

I've upgraded to iOS 7 on my iPhone 4s, cleared photos, cleared and turned off Photo Stream, deleted large apps, books, etc… and this is the 4th time I've installed iOS and started from scratch since the release of the new OS update, and yet I still get minimum of ~10GB of this "Other" data on my phone which doesn't let me include the data and files I want to have on my phone.   Any ideas or suggestions?


listing providers in a given range depending on their actual distance

my objective is layed out on a pic (thought it will be easier ). My curiosity is is,  is it how its done in the real world in the sense of mechanism wise. if there are millions of rows in that table wouldn't it take so long to make the calculations list any other options. what is generally used in the real world to achieve this  thank you for your help.


Reflexivity, Transitivity, Symmertry of the square of an relation

$\def\p{\mathrel p}$If $\p$ is a relation on a set $A$, define $\p^2$ by $a \mathrel{\p^2} b$ if and only if there exists $c$ with $a \p c$ and $c \p b$.   If $p$ is reflexive/symmetric/transitive does $p^2$ have the same properties?  I'm not even sure how to start this, I assume I would need to use the $a$ related to $c$, $c$ related to $b$ somehow?


We have a series of monthly data for 20 months (it is not possible to obtain more data). These are the number of medical consultations encoded in a public hospital and we only have monthly data for two years.  We would like to predict some future values for this series since our goal is to see if doctors are adopting the coding system. Which method do you suggest to use to forecast this kind of series?


Is there a way to show Spotlight indexing status/progress in Yosemite?

In previous versions of OS X, you could click the Spotlight icon in the menu bar to show the status of the Spotlight indexing, and it would show an estimate ("6 hours left"), along with a progress bar.  I've updated to Yosemite yesterday, and I noticed that Spotlight is not showing some expected results, i.e. files I know to be there, but it just doesn't find them if I type in their name and file type ("kind:excel vacation").  When I start typing in the Yosemite Spotlight window, it shows a small progress bar under the search box, but there's no estimate.    Is there another way to show the progress or an estimation on how long the indexing is going to take?


Calculating size of cap & inductor for buck convertor

What is the idea of choosing inductor & capacitor value for buck DCDC convertors (no specific part number, in general)?  I've tried random one with low resistance, and it kinda works, but want to know idea behind calculation of optimal value (based on freq, and max current).


Exclude paths that make find complain about permissions

I need to generate a file list from a disk volume. Some of the directories (all hidden directories under the root directory) have strange permissions that causes find to complain.  I try to exclude all these paths, but one directory still complains:  find . -type f -not -path './.*/*' find: ./.DocumentRevisions-V100: Permission denied   The rights are like this (set so by the operating system, so I assume they shouldn't be messed with).  d--x--x--x root  wheel   .DocumentRevisions-V100   How do I change the find statement to effectively omit all the hidden directories as to not complain. (I do not want to do 2>/dev/null as I want to know about other problems).


Is friction really independent of surface area?

All of the sources I read says that friction is independent of surface area, but when we throw a heavy object with large area from a certain height, it experiences more air drag, which is related to friction, but when we throw another object of equal mass and smaller surface area, it experiences less drag.  Also, a circular or spherical wheel like structure experiences less friction than a cubical block of equal mass and equal co-efficient of friction.  Can you explain me why it happens?


How can I select rows from a hierarchical query with the lowest level?

Apologies for the cross-post from StackExchange DBA - I wasn't sure which site was best for this question.  I have a hierarchical query in Oracle 11gR2 that returns something like this:   Parent (Level 1)  Child (Level 2)  Grandchild (Level 3)  Child (Level 2)  Grandchild (Level 3) Grandchild (Level 3)  Child (Level 2)    The query I would like to write should get all the rows matching some predicate, for the minimum level; i.e. nearest the parent. For example, if one of the child rows matches the predicate, it should return just that row, irrespective of whether any grandchild rows match. If multiple child rows match, it should return all of them, again irrespective of grandchild rows. If no child rows match, it should return any grandchild rows that match, etc. (In the real system I have a lot more than three levels, and lots more rows per level.)  I assume this is possible with analytic functions, but I'm not sure which one to use, or how to integrate it into my query. I've seen similar problems solved using min (level) keep (dense_rank last order by level), but that doesn't seem to do quite what I want.


I need to be able to open about 16 JPGs in Chrome all at once, without having to select each one and do Open With. When I select multiple files, the Open With option disappears. How do I make it available with multiple files selected?  Several answers so far have provided decent workarounds, but they're not very flexible when I work on a large variety of files where Open With would be useful. Is there a way to actually do Open With on multiple files?  For anyone coming here in the future, I don't believe there's any proper workaround. If this matters a lot to you, I've created a  in the Feedback Hub that you can upvote.


Do Humans Exist on Earth at the time of Star Wars?

The very first thing we saw in 1977 at the beginning of a New Hope was "A long time ago, in a galaxy far, far away..." It tells us that Star Wars of course takes place in the past. How long ago in the past does it take place though? At what stage of development were we on Earth during the time that Star Wars takes place?  Moreover, do we even exist during the time of Star Wars? Is there any mention of how long ago in our time Star Wars took place?


How do i insert mysql query with single quote?

I am trying to insert query with single qoute '.its break my query . e.g   INSERT INTO news (`Id`, `UserId`, `description`) VALUES (1,12,'Hello this descriptrion  and this single qoute ' in sentance');   It dose not insert and give error. so my question is whenever user enter description with single qoute e.g it's very hot today. how can i handle  '   single quote in this way ?  You Answer highly Appreciate


Difference between virtual interfaces with ifconfig and iproute2

I am wondering what is the difference between:  # ifconfig eth0:0 1.1.1.1/24   and just  # ip addr add 1.1.1.1/24 dev eth0   Btw I cannot do  # ip addr add 1.1.1.1/24 dev eth0:0 RTNETLINK answers: File exists   In ip addr show it appears differently :  eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000  link/ether 8c:ae:4c:fe:1f:75 brd ff:ff:ff:ff:ff:ff inet 1.1.1.1/24 brd 1.1.1.255 scope global eth0:0 ---> with ifconfig inet 2.2.2.2/24 scope global eth0 ----> with ip   When should I prefer the first way and when should I prefer the second way? It seems more cool to


Booting from Live USB without typing "live"

Can I set "live" as the default option so that I don't have to type it each time I boot the PC?  Can the config file below be changed somehow to achieve it? Currently it looks so. I've never changed it before.  $ cat syslinux/txt.cfg default live label live menu label ^Start Kubuntu kernel /casper/vmlinuz append noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/kubuntu.seed boot=casper maybe-ubiquity initrd=/casper/initrd.lz quiet splash --- label check menu label ^Check disc for defects kernel /casper/vmlinuz append noprompt boot=casper integrity-check initrd=/casper/initrd.lz quiet splash --- label memtest menu label Test ^memory kernel /install/mt86plus label hd menu label ^Boot from first hard disk localboot 0x80   It's Ubuntu 16  Please, mark this question as duplicate of   The answer that worked for me was


Material colors are showing only after render in Blender 2.8

I'm new to blender and started to create something using tutorials. I created an object and added some colors to it then render the object and everything worked fine then I saved it.  But when I opened the saved blender file again it is not showing any of colors but when I render it shows the same object as I saves with colors.  Not sure if something changed in the settings.    The rendered Image:


What was the entrance to the Chamber of Secrets before indoor plumbing was invented?

by Salazar Slytherin and the other three founders.  But indoor plumbing (i.e., running water through pipes) wasn't developed until - well, I'm not sure, but . Now, Pottermore confirms it:   So the secret entrance to the Chamber of Secrets clearly wasn't via some kind of .  And I believe it unlikely to have been through the  because, though it certainly would have been an excellent disguise for it, I can't see Salarar Slytherin building it that way for reasons of dignity.  So, what was the original design, when was the Castle renovated with indoor plumbing, who built the current secret entrance during those renovations, and how was it kept secret from all the other occupants of the Castle at that time and also the other renovators?


Calculate price and quantity using jquery or javascript

How to calculate price and quantity. I don't want to remove currency type. The price is php generated so i just want to show a calculated price when update quantity using jquery or javascript. Thank you.   Here is working demo :     $('input[name=\'quantity\']').on('change keyup click', function() {  var price = $('.price').text().substr(1);   var quantity =  $('.quantity').val();      $('.total').text(price * quantity);      });  Total : $50.00
 Price : $50.00
 <input name="quantity" class="quantity" value="1" />


How to compare 2 rows in SQL and see if the same ID Like each other match?

Hi I am trying to match 2 rows from same table? For example below are the 2 rows of a single table. I wan to know if the primaryuser has liked the likeduser and the same liked user under primary user liked the primary user. For example  primaryuser   LikedUser   Likes 101           102         Yes 102           101         Yes 103           102         No 104           301         Yes     O/P: 101, 102   here when 101 was primary user they liked user with ID 102 and when 102 was primary user they liked user with ID 101 so they have mutually liked each other.


If $A\subset B$ then $\bar{A}\subset \bar{B}$

Please let me know if you find my proof satisfactory.  Let $A\subset B\subset \mathbb{R}^n$, where $\bar{A}$ is the closure of $A$.  If $\vec{x}\in \bar{A}$ then $\vec{x}\in A^\circ$ or $\vec{x}\in ∂A$ (in the boundary of $A$). If $\vec{x}\in A^\circ$ then $\vec{x}\in A \implies \vec{x}\in B\subset \bar{B}$. If $\vec{x} \in ∂A$ then $B_\varepsilon(\vec{x})\cap A\ne \emptyset \ne B_\varepsilon(\vec{x})\cap B$ (for any $\varepsilon > 0$). Thus, since $A\subset B$, $\vec{x}\in B \implies \bar{A}\subset \bar{B}$.


What do you call sentence structures with unnecessary pronouns?

Examples: "The father, he was very angry." instead of "The father was very angry" "The cup, it was overflowing." instead of "The cup was overflowing"  I have seen it in dramatic texts, especially where a special emphasis is needed for dramatic effect. But recently I have heard this guy on youtube do this with almost every sentence with a subject and it's jarring and weird.  I wonder what this grammar style is called.


Derive the distribution of $X +\frac{a Y}{Y+b}$, with $X$ and $Y$ are exp. r.v

Define $X$ and $Y$ to be two exponential random variables. The probability distribution functions are $f_{X}(x)=\lambda e^{-\lambda x}$ and $f_{Y}(y)=\delta e^{-\delta y}$. Note that $X$ and $Y$ are independent.  Define $Z=X +\frac{a Y}{Y+b}$, where $a$ and $b$ are some positive constants. My goal is to derive the CDF of $Z$, i.e. I want to calculate $P(Z <z)$.  My approach consists in deriving the CDF of $R=\frac{a Y}{Y+b}$, and then trying to find the CDF of the sum, which will be a function of the CDF of $R$. So I have started as follows: $P(\frac{a Y}{Y+b} < r)=P(Y(a-r) <rb)$. It is clear that here $a$ should be $>r$, because otherwise we get something negative.. Thus, following this approach forces us to assume that $a>r$, something that I don't know if I can assume or not.    Question: is this assumption necessary to be able to derive the CDF? is there any other approach that I can adopt to derive the CDF without making this assumption?


Having problems in storing string from startActivityFromResult

What I want to do is:   When I launch the application, the main activity's interface will be shown but the Global String will have no data stored.  Then when I click the button in the MainActivity, I will be directed to the next Activity. In this 2nd Activity, there is an EditText where I can input anything I want. Then if done typing in the editText (lets assume EditText is the same as if-statement condition needed to execute), I will click the button in the 2nd Activity and pass the intent to the MainActivity class. In the MainActivity, I want to get the intent passed by the 2nd Activity to store it in my String and when I click the button in MainActivity it will show a message that will display a toast saying "Successful".    My problem lies in step 5, when I click the button, it does not show "Successful"; it shows "Error". Assuming that I've typed what I want is the same as what I needed in the if-statement.  My Codes are:   Floating Action Button Codes:   FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);         fab.setOnClickListener(new View.OnClickListener() {             @Override             public void onClick(View view) {                 Intent i = new Intent(MainActivity.this, SearchCategory.class);                 startActivityForResult(i, 0);             }         });   Note: This is the button that opens the 2nd Activity  In my 2nd Activity button click codes:  public void search(View view) {      editText1 = (EditText)findViewById(R.id.start_text);     type = editText1.getText().toString();        Intent intent = new Intent();     Bundle bundle = new Bundle();     bundle.putString("type", type);     intent.putExtras(bundle);     setResult(RESULT_OK, intent);     finish();  }   The Button Click in Main Activity  public void onButtonClick(View view) { if (start == "Car") {             Toast.makeText(this, "Successful", Toast.LENGTH_LONG).show(); } else { Toast.makeText(this, "Error", Toast.LENGTH_LONG).show(); }   On ActivityResult Codes:  @Override     protected void onActivityResult(int requestCode, int resultCode, Intent data) {         super.onActivityResult(requestCode, resultCode, data);         if (resultCode == RESULT_OK) {             /*EditText et = (EditText)findViewById(R.id.text_category);*/              Bundle category = data.getExtras();             category_text = category.getString("type");              /*et.setText(start);*/         }     }   Note: I've tried adding an editText in main activity, it shows the text that I typed in the 2nd activity's editText.


Let $k, n \in \mathbb{Z}$.   How can I find a solution for this problem?  Also, where are some resources to solve a similar problem? I came across this question when attempting to find a solution to $2^n \equiv 0 \mod 12$.


Why are conditionals with false antecedents considered true?

I don't understand what conceptual sense this scenario makes, or what the motivation behind the decision to make conditionals with a false antecedent true was. Can anyone help me understand this?   Also, I have a related but ultimately separate question on something read in a book. I am reading "Introduction to Logic: and the Methodology of Deductive Sciences" by Alfred Tarski, which gave the following example after defining implications.   If 2*2 = 4, then New York is a large city;  If 2*2 = 5, then New York is a large city;  If 2*2 = 4, then New York is a small city;  If 2*2 = 5, then New York is a small city.    It then says the following, "In everyday language, these sentences would hardly be considered as meaningful, and even less as true. From the point of view of mathematical logic, on the other hand, they are all meaningful, the third sentence being false, while the remaining three are true."   What is it that makes the third sentence false? No further explanation for this is given in the book.


Why did mathematicians introduce the concept of uniform continuity?

I have solved many problems regarding uniform continuity, but still I can't understand the following:  Is there any practical application of this concept, or it is just a theoretical concept? Is there any wide application of this concept in any theorem or problem? In short, how did the concept of uniform continuity arise?


I am using Ubuntu 14.04. I'm trying to change the title text of the windows in Unity to the center.   I saw this tutorial:   But it does not work. Could you help me?


What benefits do you get from the Belt of Dwarvenkind without attuning to it?

The description of the  (DMG, pg. 155) says the following:  Belt of Dwarvenkind Wondrous item, rare (requires attunement) While wearing this belt, you gain the following benefits:  Your Constitution score increases by 2, to a maximum of 20. You have advantage on Charisma (Persuasion) checks made to interact with dwarves.  In addition, while attuned to the belt, you have a 50 percent chance each day at dawn of growing a full beard if you're capable of growing one, or a visibly thicker beard if you already have one. If you aren't a dwarf, you gain the following additional benefits while wearing the belt:  You have advantage on saving throws against poison, and you have resistance against poison damage. You have darkvision out to a range of 60 feet. You can speak, read, and write Dwarvish.   The way I read this, only the stuff about your beard growing requires you to attune to it. Am I reading this right? Do you really gain everything else (excluding the stuff at the end if you're a dwarf, obviously) even if you're not attuned to it? Or is it the case that because the belt requires attunement, it's implicit that everything it does requires you to have attuned to it, and the way it's worded is just tripping me up?


A lot of flushleft's causes longtable to overfull page

I'm  using longtable to write tables that span across pages. But when I use it after some environments like flushright, it overfull page and overlap page number like this.   Here is code (I'm using XeLaTex):  \documentclass[oneside,final,14pt]{extreport}  \usepackage[a4paper]{geometry} \geometry{left=3cm} \geometry{right=1cm} \geometry{top=2cm} \geometry{bottom=2cm}  \usepackage{longtable}  \begin{document}             \begin{flushright}         \vspace{1cm}     \end{flushright}     \begin{flushleft}         \vspace{1cm}     \end{flushleft}     \begin{flushright}         \vspace{1cm}     \end{flushright}     \begin{flushleft}         \vspace{1cm}     \end{flushleft}     \begin{flushright}         \vspace{1cm}     \end{flushright}     \begin{flushleft}         \vspace{140mm}     \end{flushleft}     \begin{longtable}{|l|l|}         \hline         Test & Test \\ \hline         Test & Test \\ \hline         Test & Test \\ \hline         Test & Test \\ \hline     \end{longtable} \end{document}   And when I add one more Test & Test \\ \hline, table magically typesets normally. What am I doing wrong?


net beans 8.1 not running only until reading modules

I have this in my terminal for checking  martin@martin:~$ sudo update-alternatives --config java There is 1 choice for the alternative java (providing /usr/bin/java).    Selection    Path                                     Priority   Status ------------------------------------------------------------   0            /usr/lib/jvm/java-8-oracle/jre/bin/java   1081      auto mode * 1            /usr/lib/jvm/java-8-oracle/jre/bin/java   1081      manual mode  Press <enter> to keep the current choice[*], or type selection number:  martin@martin:~$ java -version java version "1.8.0_131" Java(TM) SE Runtime Environment (build 1.8.0_131-b11) Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)   Still my netbeans 8.1 is not starting up it is only starting up until reading modules and I dont know what is the error.  Also I added   netbeans_jdkhome="/usr/lib/jvm/java-8-oracle"  In netbeans.conf As it was an accepted in a post but it didnt work for me.   I already tried uninstalling and installing a couple of times but it still didnt work.   I am out of idea right now and I hope some one will point me to the right direction  UPDATE  martin@martin:~$ javac -version javac 1.8.0_131   tried to run  martin@martin:~$ sudo chown -R martin:martin ~/.cache/netbeans [sudo] password for martin:  martin@martin:~$    from this  still didnt work


Represent integers as a sum of Fibonacci numbers

Let $f_n$ be the Fibonacci sequence, $f_1=1$, $f_2=2$.       Prove that each positive integer admits a unique representation in a form $a_1f_1+a_2f_2+\cdots+a_nf_n+\cdots$ such that      1) each $a_i$ is either $0$ or $1$;        2) there are finitely many numbers $a_i$ equal to $1$;          3) no two consecutive numbers are equal to $1$.   Attempt:  Since every Fibonacci number can be represented as $1$ times itself, obviously satisfying above three properties, we only need to show integers between every two consecutive Fibonacci numbers satisfy three properties.  Since the gap between two consecutive Fibonacci numbers $F(n)$ and $F(n+1)$ is equal to $F(n-1)$, we only need to show that integers from $1$ to $(F(n-1)-1)$ can be represented in the required form, since we can add them to $F(n)$ to get every integer in the gap between $F(n)$ and $F(n+1)$.  I try to use induction.  The first Fibonacci number subtracted by $1$ that is not another Fibonacci number is $F(4)$, since $F(4)-1=4$, $1$ to $4$ obviously satisfy three properties.  Suppose $1$ to $F(n)-1$ can be represented in the form satisfying three properties, we prove $1$ to $F(n+1)-1$ can also do that.  However I found it hard to continue, maybe this is not a good idea in the first place. Is there a better way to do this problem? Another question is that I don't understand what the point of the second property is. Since there are only finitely many Fibonacci numbers that are less than a integer, how could it possible to represent it as a combination of them with infinitely many coefficients that is equal to $1$?


Unable to run query gives mySQL error #1093 - You can't specify target table 'members' for update in FROM clause

I have been working on a Query that takes the subset of the table records and update them but somehow i am unable to make it work it give me error #1093 - You can't specify target table 'members' for update in FROM clause  Here is the Query:  UPDATE members set is_deleted = 1     WHERE EXISTS       (SELECT m1.member_id FROM members as m1            WHERE m1.member_id NOT IN                (select member_id                     from membership_payment_profiles                     WHERE (next_date_to_charge > "2012-12-31 00:00:00"                     or next_date_to_charge is null)           order by next_date_to_charge DESC ) and m1.joined_on < "2012-12-31 00:00:00" )


Difference between $\sin(\arcsin(x))$ and $ \arcsin(\sin x)$

What's the difference between $\sin(\arcsin(x))$ and $ \arcsin(\sin x)$ ? I think these are equal each other and equals to $x$ . Also , what's the plot of these functions ? I'm really confused about inverse function and its concept that is appearing in many situations and problems like this.


How to avoid the potatoes from sticking to the pan while frying for french fries/finger chips?

Sometimes when I fry the potatoes for french fries, the potatoes stick to the pan which irritates me and I can't separate the potatoes because if I use the spoon a lot, it will cut the fries into pieces. Due to the scarcity of resources, I can't manage to buy a non-sticky pen. Kindly recommend me some solution.


Confused with TeX terminology: height, depth, width

The LaTeX reference card states for example     \strut box w/ ht and depth of “(”, zero width   I came to see text as a two dimensional feature, but I must be missing out on something...  (following was off-topic: by the way, im trying to find documentation on how to use \vbox, \hbox,… i.e. to align a hbox within a vbox to the right)


I have 2 Monitors and want to observe on one monitor 1st sheet and on the other monitor 2nd sheet but no matter how many excel files I open they are all on one monitor.  Can I split them to two screens?  I have Excel 2007 and working on 2003 file. Thanks a lot for your time!


The multiple-choice question:  A hotel has four vacant rooms. Each room can accommodate a maximum of four people. In how many different ways can six people be accommodated in the four rooms? (A) 4020 (B) 4068 (C) 4080 (D) 4096.  My attempt:  If there were no 'four person' constraint, the six people could be accommodated in $4^6=4096$ ways. however, this number includes combinations with 5 or 6 people in one room, which should be excluded.  If one room has 5 occupants, one other room has 1 occupant. The number of '1,5' combinations is ${{4} \choose {2}}$=12. If one room has 6 occupants, the other three rooms have no occupants, and there are four such combinations.  I believe the answer should be $4096-12-4=4080$, but am not confident. I'd be grateful for any comments on my attempt.


How to execute command automatically after opening putty saved session using cmd

Is there a way to ssh to my server and execute command automatically. To ssh to the server I open cmd then type putty -load "saved_session" to load my saved session(). is there a way I can add a command that will execute automatically after I ssh ?


Where does Chrome gets its list of certificate authorities from?

On Fedora, I'm talking about the list displayed when you go to settings > manage certificates > authorities tab.  I've read that it should be in the NSS shared DB, but this command returns an empty list:  [laurent@localhost nssdb]$ certutil -d sql:$HOME/.pki/nssdb -L


Is it true for finding the order of $\mathbb{Z}_n[x]/ \langle f(x) \rangle$?

This question long-time bothering me.   Let  $f(x) = 2x^2 + 5x+1$  Find the order of $\mathbb{Z_{10}}[x] / \langle 2x^2 + 5x +1 \rangle $    My friends said it is not difficult. He suggested the solution like the below  $\mathbb{Z_{10}}[x] / \langle 2x^2 + 5x +1 \rangle \simeq \mathbb{Z_{2}}[x] / \langle 2x^2 + 5x +1 \rangle \times \mathbb{Z_{5}}[x] / \langle 2x^2 + 5x +1  \rangle  $  Question) Is it really true? then why? I'm doubt about his solution. Any help would be appreciated.    p.s.) Why having  I the doubt for his solution.  The link I asked)  The link2 I asked)


Would metal bullets be more effective against a lightsaber?

I've been wondering, we always see lightsabers reflecting blaster lasers which, supposedly, are raw energy. We get no indication that there is actually any substance to a lightsaber's blade, so wouldn't a bullet just go straight through it, melt, and then plaster the Jedi's face with molten metal?  Or is there a fact I'm missing?  (We see that lightsaber blades melt metal, not vaporize it into steam, but even if that was the case I don't think a face full of metal steam would do you much good either.)


New to Automation , I am using selenium with JAVA.  I have come across a stumbling block our developers do not assign ID to our elements and JFS assigns it own ID , however the ID's are dynamic and keeps on changing.  Also the xpaths and css selectors also contains the dynamic id's.  I have seem some methods of using contains , starts with , however cannot seems to get it correct , when I inspect my element I get below   <button type="button" class="ui-datepicker-trigger ui-button ui-widget ui-  state-default ui-corner-all ui-button-icon-only" aria-label="Show Calendar"  aria-haspopup="true" role="button" aria-disabled="false">ui-button</button>   xpath - //[@id="j_idt67:j_idt69:j_idt70:j_idt100:j_idt101:calendar"]/button  css selector = #j_idt67\3a j_idt69\3a j_idt70\3a j_idt100\3a j_idt101\3a  calendar > button   I f anyone could assist and advise on how you would locate the element and insure that it would not change , would be of great assistance , if you require further info , let me know , like I said new to automation


Is it true that $\gcd(ta,tb)=t\gcd(a,b)$ in a domain?

Is it true that in a domain $R$, $\gcd(ta,tb)=t\gcd(a,b)$?   I know how to prove it in $\mathbb{Z}$, but what about if it's an arbitrary domain $R$?


The limit as $n$ approaches infinity of $n(a^{1/n}-1)$

I need to know how to calculate this without using l'hospitals rule:  limit as $x$ approaches infinity of: $$x(a^{1/x}-1)$$  I saw that the answer is $\log(a)$, but I want to know how they got it. The book implies that I should be able to find it by just using algebraic manipulation and substitution.


Accept question of type "What is the best..." on any other sibling site, not necessarily Stack Overflow

I highly think that question of type "What is the best..." bring a lots of useful information to people. Perhaps it should not be accepted in Stack Overflow, I agree.  But I would really appreciate to have access to a site where I could ask those kind of questions. Ideally, the site will have a similar well tuned awards system as Stack Overflow. Also it would be nice if that site would have a very nice popularity as Stack Overflow. For each user on that site, just beside its reputation could be displayed the reputation from Stack Overflow (without being able to affect it) if it exists, that way it could help to evaluate the quality of an answer.  To add some considerations (explanations) to my suggestion, I invite you to read one of my really not popular question at meta.stackoverflow.com:   Sorry I just discover  as Emrakul told me. You can close this, I can't ! In "Contact us" they do not mention how to send suggestions.  If anybody can close that, I would appreciate. Sorry to disturb !  FYI: Please take a look the fourth in the most voted questions on StackOverflow (not subjective ???) !!! And I would be surprise to see all others that are deleted :-) !


Is there a word to describe something that is not our own?  For instance:  The thoughts I was having were not my own, they were _______.  A possibility I thought of is alien.


Bash script to execute multiple Unix commands

I have some commands that take too long to execute so I need a bash script to execute them serially.  The commands:  cd ~/my_file  command 1  command 2 ... command n    This is on Ubuntu 18.04. How should I do it?


Use of definite article referring to figures and tables

There are tables and figures in a document, uniquely identifiable by their numbers.   We want to refer to them in several places. Which one is preferable in academic English writing and why?        In figure 1 ...   In the figure 1 ...   With the help of table 1 ...   With the help of the table 1 ...   Lemma 1 helps ...   The lemma 1 helps ...


Can I make my last ball and then the 8 ball in the same shot in 8 ball pool?

If I make my last ball, and the cue ball travels around the table and pockets the 8 ball in the same pocket, do I win or lose?    After all I made the 8 ball in my last pocket and you don't have to call your last pocket since it's the only choice you have unless your playing a 3 or more rail.


Use unpacking to concatenate nested list

I have such a nested array   In [12]: print(f"{arr}")                                                                  [[0, 1, 2], [7, 8, 9, 10], [12, 13, 14, 15, 16, 17]]   I want to concatenate the three arrays inside   arr = [[0, 1, 2], [7, 8, 9, 10], [12, 13, 14, 15, 16, 17]] res, k = [], 0 for i in range(len(arr)):      for j in range(len(arr[i])):          res.append(arr[i][j])   or   In [26]: [arr[i][j] for i in range(len(arr)) for j in range(len(arr[i]))]                                  Out[26]: [0, 1, 2, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17]   How could use unpacking to handle the problem   In [27]: [*a for a in arr]                                                                                File "<ipython-input-27-4ab599207747>", line 1     [*a for a in arr]     ^ SyntaxError: iterable unpacking cannot be used in comprehension


What does a unit like $C^{1/5}$ or $kg^{1/2}$ physically mean?

I'm more of a math guy than a physics guy so bear with me....  In fractal geometry, fractals are considered to have fractional dimension. For instance an object such as the Koch curve has a fractal dimension of around $1.2$. You can also define a concept called fractal extent (which is the experimental version of hausdorff measure). This extent is a measure of how large a fractal is. It's even been used to more accurately model the distribution of coastline bird nesting.   Even though fractals work as an interpretation of geometrical units, I don't think they would describe things such as $kg^{1/2}$ very well. In addition, I've heard about white Gaussian noise that has square root time units.   What is the physical meaning of fractional units such as the above? (Since it obviously has little geometric meaning)


Does 'My favorite place, in my bathroom, is hot.' make sense?

My favorite place, in my bathroom, is hot.'   Does this sentence above make sense?  If it is wrong, how can I rephrase it?


Let $A,B \subset \mathbb{R}$. Show that $\sup(A \cup B) = \max\{\sup A, \sup B\}$   Here's what I did so far:  Let $\sup A, \sup B$, and $\sup (A \cup B)$ denote upper bounds of $A,B$, and $A \cup B$, respectively. If $x \in A$, then $x \le \sup A$. If $x \in B$, then $x \le \sup B$. In either case, $x \in (A \cup B)$. So either $x \le \sup A$ or $x \le \sup B$. In either case, $x \le \max \{\sup A, \sup B\}$. So $\max \{\sup A, \sup B\}$ is the upper bound of $A \cup B$, which means $\sup (A \cup B) \le \max\{\sup A, \sup B\}$.  I do not know if there's a better way to go at it, but all I did was show the inequality. Can I do this, and show the reverse inequality? If so, how can I go about doing that?


How to tell when a fraction does not end?

Is there a way in math / programming to tell if a fraction (reciprocal in particular) does not end?  For example, 1/3 is 0.33 repeated, but 1/2 is just 0.5  Is there a way to find if 1/n for any natural number n is never ending?  Context: Writing a program and want to find out if I need to round 1/n (round in my way rather than whatever the machine does) before adding it to another digit.  E.g Since 1/3 is never ending, the machine will probably cut off some of the 3's at the end, and 1 + 1/3 = 1.33333. I want to be able to catch that 1/3 is never ending (or if 1/n is Not never ending) so that when I add a "never ending" number to 1, I can round it in my own way (i.e. I can round 0.3 up to 0.5, rather than the computers way of rounding never ending reciprocals / fractions).


Prove that $\sqrt{6}-\sqrt{2}-\sqrt{3}$ is irrational   My attempt:-     Suppose $\sqrt{6}-\sqrt{2}-\sqrt{3}$ is rational, then for some $x\in\mathbb{Q}$ we have $$\sqrt{6}-\sqrt{2}-\sqrt{3}=x$$ Rewriting this equation as $$\sqrt{6}-x=\sqrt{2}+\sqrt{3}$$ and now squaring this we get $$ 6-2x\sqrt{6}+x^2=5+2\sqrt{6}$$. This implies that $$\sqrt{6}=\frac{x^2-1}{2+2x}$$ but this is absurd as RHS of the above equation is rational but we know that $\sqrt6$ is irrational. Therefore , $\sqrt{6}-\sqrt{2}-\sqrt{3}$ is irrational. Does this look good? Have I written it properly? Is there any other proof besides this..like one using geometry? Thank you.


Audio cuts out when CPU usage rises above ~30%

I've just built a new PC:   Intel Core i3 2100 CPU 4GB 1333MHz DDR3 memory Intel H67 Chipset motherboard Using the onboard graphics Using the onboard sound - Realtek* ALC662 audio codec   When playing audio only it appears to be OK, but when playing videos and games the sound will repeatedly cut out for approximately a second 2 or 3 times and then start again. When it does cut out we get a notification that the speakers have been unplugged (although clearly they haven't).  One piece of information we found indicates that it's  and this does seem to be the case. It would also explain why it's more of a problem when video is involved as the CPU is doing everything.  We've checked that we've got the latest drivers installed and if anything the problem seems to be getting worse.  Is the only solution going to be getting a dedicated graphics card?   doesn't answer the problem.


What do I lose when I quit a multiplayer game in BF3?

When I quit a multiplayer game in BF3, the game warns that "All progress will be lost". But I'm wondering if experience and unlocks will also be lost.


I want to make a fighter whose primary weapons are his unarmed attacks using the Tavern Brawler feat. If I take the Two Weapon Fighting style would that work with 2 unarmed strikes? In the weapons table it doesn't have the light property generally required for fighting with two weapons, but they're fists.


How do I map root domain to external subdomain

I'm trying to map somedomain.com to here.anotherdomain.com. I can do any sub domains of the original using a CNAME but the root domain ( somedomain.com ) needs an A record. This is currently set to the ip address of the server ( anotherdomain.com ).  My question is, do I add a CNAME record of somedomain.com to point to here.anotherdomain.com on the server DNS zones?  NAMESERVER RECORDS A somedomain.com 123.123.123.123 CNAME www here.anotherdomain.com  SERVER RECORDS CNAME somedomain.com here.anotherdomain.com   The nameservers are at codeigniter and the server is cPanel.  Thanks for any help  Joe


Got not sufficient privileges message in CMD when logged on as administrator

I was trying to use mklink command in cmd (I have Windows 7 OS) I was logged on as administrator, but I got:  You do not have sufficient privilege to perform this operation.  I used the same command in Vista, it worked OK. Any ideas why it does not work in Windows 7?


Prove that formule is true in every realisation of language

I have language $\mathcal L$= $\{$P,Q,R$\}$, arity of $P,Q,R$ is $1,1,2$. And I have two formulas:  1) ($\forall x$ $P(x)$ $ \land $ $\forall x$ $Q(x)$) $\leftrightarrow$ $\forall x$ ($P(x)$ $ \land $ $Q(x)$)  2) $\forall x \exists y \forall z$($R(x,y) \land R(y,z)$) $\leftrightarrow$ $\forall x \forall y \exists z$($R(x,y) \land R(y,z)$)  ,for which I have to prove (or disprove) that they are true in every realisation of language $\mathcal L$. My problem is that I don't know how to do that. I know that first one is a tautology and sure that second one isn't, but I don't know how to prove that something true in every realisation of $\mathcal L$.Can anyone formulate to me, how do I prove that?


Does deleting iCloud photos affect them on devices?

If I delete a photo from my iCloud will it also be removed from my devices that are connected to my account?


Don't charge the battery but use connected power to run the phone

Answers to this question  explain how charging while phone is in use does both - charging the battery and powering the on going activities.  My question is different — Can I stop charging the battery but use the connected power for ongoing activities?  Why do I want to do this?    I want to charge the battery within ideal limits (see )    and    at the same time use the charging power to keep running the phone without any heat stress on battery, thus extending battery life.  Also the battery is not drained, enabling me to use the phone for longer time without charging   Edit : I am not looking for dedicated cables or hardware that can possibly do this


Dope sheet editor. What does the orange line between keyframes mean?

I start to use the dope sheet view to see my key frames. But I don't understand why for some I have an orange line and not for others like below. What is the meaning of the orange line between keyframe?


I would like to receive a dataset of N elements and group it every 59 elements, considering that the first element would have the index 0. The problem in this script is that in the sample.append(data [i]) part, it groups all the data again in a single list, I would like to divide it as follows. [[60 elements], [60 elementps], ...]. Any suggestions for correction?  Script:  @staticmethod         def sampleDivision(data):     parts = int(len(data) / 60)     collections = []     i = 1     while i <= parts:         i * 60         collections.append(i * 59)         i += 1     print(collections)     i = 1     sample = []     for position in collections:         while i <= int(position):             sample.append(data[i])             i += 1      return sample   Output:  [68, 69, 68, 69, 70, 71, 75, 72, 73, 72, 72, 73, 72, 72, 73, 70, 71, 73, 72, 72, 71, 69, 68, 69, 68, 69, 68, 69, 68, 68, 68, 68, 69, 68, 69, 70, 71, 75, 72, 69, 68, 68, 68, 69, 68, 69, 70, 71, 75, 72, 69, 68, 69, 68, 69, 68, 69, 68, 68, 60, 60, 61, 60, 61, 65, 69, 69, 72, 73, 72, 72, 73, 72, 72, 73, 70, 71, 73, 75, 78, 80, 82, 84, 87, 84, 84, 83, 82, 79, 78, 76, 74, 73, 72, 72, 72, 71, 75, 72, 69, 68, 68, 68, 69, 68, 69, 70, 71, 75, 72, 69, 68, 69, 68, 69, 68, 69, 68]


Proof that $2(a^4+b^4+c^4)<(a^2+b^2+c^2)^2$ if and only if line segments of length $a$,$b$ and $c$ form a triangle

Obviously I tried to somehow manipulate the triangle inequality $a<b+c$ $a^2<(b+c)^2$ Similarly, $b^2<(a+c)^2$ and $c^2<(a+b)^2$ After adding these together: $a^2+b^2+c^2<(a+b)^2+(a+c)^2+(b+c)^2$ But it seems I even work in the wrong direction, cuz I have to find the lower bound on the sum of squares, not the one on the top. So then I tried to rewrite the triangle inequality like that: $c>a-b$ $b>a-c$ $a>b-c$ and work from here but I also didn't manage to get to the point, where I feel like I have this problem in my bag


I have answered some time ago an old question   And now someone added bounty to this question with comment:     Current answers are not full. Please give exact working examples.   I'm sure, than my answer has fully working example. Can I contact him and ask for more details?  Can I notify him by simply putting @HisName into comment?


Can RIGHT OUTER could be written as a LEFT OUTER by just flipping the tables

Can we use right join instead of left join and vice versa by just flipping the table position in the query.If so then why we need both joins?


Example of integral domain with infinitely ascending chain of ideals.

I am looking for an integral domain in which we have an infinitely ascending chain of ideals.   Clearly, this can't be a PID. Also, I am looking for examples other than infinite dimensional fields, integral domains like $k[x_1,x_2,\dots]$.


I'm having trouble understanding how Herbrand models work. I feel like there is a bigger picture to it which I'm not understanding. Why does every satisfiable first order formula have a herbrand model at all ? Can I somehow construct a Herbrand model from a normal model ? My book also says that : a formula is unsatisfiable iff the Herbrand expansion is unsatisfiable. The book I'm using "Mathematical Logic for computer science by Mordechai Ben-Ari" has all the proofs of the above but its not very intuitive to me. Could somebody share their point of view?


How to print a graphic on a glass window

I have a glass window (a plane object) on which I want to print a graphic.  However, the glass turns black. below is a screenshot of the shader set-up I used. What did I do wrong?


How to mute the microphone on Key-Down and unmute it on Key-Up?

What I would like to have is:   By default the microphone should be muted When CapsLock is Down the microphone should unmute When CapsLock is Up the microphone should mute   (Basically convert my Skype to act like a Walkie-talkie with a  functionality)  I  the AppleScript that can change the volume input of the microphone, so the first step was easy, but I didn't find any way to even assign the CapsLock to a script. Note that my CapsLock key is turned off and I would't like to sTART experiencing something like tHIS.  If the CapsLock is very special I wouldn't mind using another key, but I want to achieve the same functionality.  Edit: Probably it is not really possible to do it without using any application, so if there is an app that can do that, it would also work for me.


Is $\frac{\sin x}{x}$ uniformly continuous on real line

$\frac{\sin x}{x}$ is uniformly continuous on a closed interval as it is continuous, but how to extend it to whole real line. Choosing  what $\delta$ can I proceed?


Are there any vegetarian-friendly egg substitutes that can be used in cakes?

I spent about 2 1/2 years as a lacto-ovo vegetarian but, I gave up eggs in October. The problem is that I really like cake. Unfortunately, the cake recipes that I've found that don't use eggs produce very dense cakes. Is there a way around this?


Help with proving that $\phi(n)$ $\ge$ ${\sqrt n} \over 2$

So far I have  $${{\phi(n)^2} \over n} = n \prod_{i = 1}^k \left(1 - {1 \over p_i}\right)^2$$  We know that $$\left(1 - \frac{1}{p_i}\right) \geq \frac{1}{2}$$  So $$n \prod_{i = 1}^k \left(1 - {1 \over p_i}\right)^2 \geq \frac{n}{4^k} = \frac{n}{2^{2k}}$$  Want to show that $$\frac{n}{2^{2k}} \geq \frac{1}{2}$$  $n \geq  2^{2k - 1}$  Got stuck here. Any help to prove this?  EDIT: Ok so I looked at the answer in the thread provided and I don't understand how $\frac{\phi(n)^2}{n}= \prod_{p|n \ \text{prime}} \frac{(p^{a_p-1}(p-1))^2}{p^{a_p}}$  There's a factor of n missing since the $\phi$ function is being squared


In a linear regression, can I both normalize the dependent variable by X and include X as an explanatory variable?

I'm performing a regression where the dependent variable is a ratio, and the explanatory variable is the denominator of that ratio. In other words, I'm normalizing the dependent variable by $X$ and including $X$ as an explanatory variable:  Dependent variable: $Y/X$  Explanatory variable: $X$  For example, I might be interested in whether countries with more people tend to have a higher proportion of women, in which case $X$ is total population and $Y$ is the number of women. Or I might be interested in how the number of dogs per cat varies with the size of the cat population in a country, and so on.  $X$ appears in both the left hand side and right hand side of the regression equation, and I want to avoid any issues that could arise from this (e.g. mechanical correlations).   Should I be worried about mechanical correlations (either generally or in certain situations)? If so, what kinds of situations, and how can I remedy them? And what other issues might arise?


Do you get the equipment of your new class when you multi-class?

When multi-classing, do you take the equipment from your new class and add it to the equipment you got from your main class?


Find the sign of the following integral: $\int_{0}^{2\pi}{\sin x\over x}$.

Am I required to know if it is positive or negative? This expression is not really integrable, not within the boundaries of the course at least. I tried comparing it to other integrals but I get zero all the time. I am not sure I have fully understood what I should do. I would really appreciate any help in this.   An attempt using an advice here: $\sin x$ between $0$ to $\pi$ equals $-\sin x$ between $\pi $ to $2\pi$. Since we are looking at $\sin x\over x$, $\int_{\pi}^{2\pi}{\sin x\over x}$ might be negative, but still is smaller than $\int_{0}^{\pi}{\sin x\over x}$, therefore, the sign is +1. Is that sufficient?


How can I configure a service to run at startup

I have a daemon that runs fine if I start it manually with the service command:  ricardo@ricardo-laptop:~$ sudo service minidlna start                     * Starting minidlna minidlna                                                              [ OK ]    but it's not configured to auto start when the PC reboots.   How can I configure it to start automatically, even if no one is logged into the PC?


Sort dynamically created div based on their id using jquery

Sort dynamically created div based on their id.  I have the html structure like below:

text 3

text 4

text 1

text 2

   These html are created dynamically.  $("#res").append("
text "+i+"
");   The order may vary(it is created using ajax in for loop). Unluckly divs are displayed in random order.(I don't know the reason).  However after appending the divs to the res div, I decided to sort the divs in correct order based on their id.  So the expected result should be:

text 1

text 2

text 3

text 4

   How can I do this?  I tried    $("#resdiv").tsort("",{attr:"id"});   and   $('#res> div').toArray().sort( function(a,b) { a.id - b.id } );   But nothing worked...  Someone can help me..


Book series about time travel from future to distant past, psychic powers?

Please help me identify this book series:  In the future, humanity has started to develop psychic powers by encouraging breeding of genetic traits. Humans find a way to travel back to a specific time in the past, and everyone is really excited. Then, the travelers discover that time (possibly different place as well?) is already ruled by aliens, and the humans get enslaved.  The aliens and humans have different kinds of psychic powers, like farseers, psychokinetic powers, mind readers, and so on, and are very powerful. There is one human whose psychic abilities were limited in the future, but in the past he becomes one of the most powerful psychics.  There is a big war pitting all the psychics against each other.  The aliens might be some sort of proto-humans. I vaguely remember them looking like humans, but bigger. Please help!


Can I access Area 51 from the Stack Exchange app?

I'm trying to access Area 51 from my Stack Exchange app. But it is not showing any options to go.  Is Area 51 accessible from the app?


The exact difference between a permutation and a substitution

I've noticed confusing definitions about permutation and substitution, preventing me from understanding the difference.  A permutation changes the order of distinct elements of a set, but this can be written as a function changing one element by another, exactly as a substitution.  So, how exactly can we distinguish between these two notions?  This question is interesting since we have these two notions in block ciphers, in which S-boxes perform substitution. The problem is that this table is used to replace one element by another, exactly like a permutation.


I use biblatex and a special fonencoding for the cyrillic alphabet. Everything works fine, only the bibliography prints an additional, unwanted string 'print' at the end of each item.  Here's my code:  \documentclass[12pt,titlepage]{article} \usepackage[a4paper]{geometry} \usepackage[russian,ngerman]{babel} \usepackage[OT2, T1]{fontenc} \usepackage[onehalfspacing]{setspace} \usepackage{times} \usepackage{csquotes}  \newcommand{\textcyr}[1]{% {\donothyphenate\fontencoding{OT2}\selectfont #1}} \newlanguage\nohyphens \newcommand{\donothyphenate}{% \language=\nohyphens}  \usepackage[backend=bibtex8,style=mla, citestyle=verbose-ibid]{biblatex} % OPTION:,citestyle=authoryear \usepackage{filecontents}% to embed the file `myreferences.bib` in your `.tex` file \usepackage{tabularx}  \begin{filecontents}{biblio.bib}  @book{mant,   title={Phraseologie im Deutschen und Spanischen: {\"U}berlegungen zum lexikographischen Konzept eines bilingualen phraseologischen W{\"o}rterbuchs am Beispiel deutscher und spanischer Phraseologismen aus dem Bereich" Religion und Volksfr{\"o}mmigkeit"},   author={Manten, Rilana},   year={2013},   publisher={Romanist. Verlag} }  @article{test,   title={\textcyr{Reprezentad2iya e1mod2ii {\guillemotleft}smekh{\guillemotright} v russkoi0  i belorusskoi0 frazeologii}},   author={\textcyr{Testova, T.A.}},      journal={\textcyr{Minsk: RIVSh}},   year={2010}  }  \end{filecontents}  \addbibresource{biblio.bib}  \begin{document}  This is a test\footnote{\cite{test} and \cite{mant}}  \printbibliography  \end{document}   I also get a warning: pdflatex x> Package biblatex warning: Bibliography string 'print' undefined at entry 'test'....  And it sais that for each entry... The output looks like this:   Does anyone have an idea what's wrong with my code and how I can get rid of the 'print' string?


Finding value of $\int^{\pi}_{0}\frac{\sin^2(10x)}{\sin^2 (x)}dx$


Pass command line arguments to bash script

I am new to bash script programming.  I want to implement a bash script 'deploymLog', which accepts as input one string argument(name).  [root@localhost Desktop]# ./deploymLog.sh name   here I want to pass the string argument(name) through command line   As an initial step, I need to append the current timestamp along with this input string to a log file say Logone.txt in current directory in the below format:  [name]=[System time timestamp1]   How it is possible?


Why does Kylo Ren's lightsaber look different from normal lightsabers?

Kylo Ren's lightsaber is very confusing. It has a cross-guard, which was discussed in another question, but I don't think this was:  Why does Kylo Ren's lightsaber look different from a normal lightsaber? Kylo Ren's lightsaber looks like stuff is coming out of it. It looks like it's fire. Why?


Coefficient of Determination (R-Squared) definition in Matlab

First of all, I have to say that my knowledge of statistics is very basic.  I was trying to fit data with a linear regression in Matlab, and I came across the problem of $R^2$ definition. I am using the free Ezyfit toolbox, but my question is about which definition of $R^2$ do I have to use in my analysis. I fitted the data both with a linear regression with intercept $y = ax + b$ and without intercept $y = ax $. I calculated $R^2$ from the definition  $$ R^2 = 1 - \frac{SS_{res}}{SS_{tot}}  $$  where $SS_{res}$ is the sum of squares of residuals and $SS_{tot}$ is the total sum of squares.   I saw that in the Ezyfit toolbox (and from what I can understand in the Matlab Statistics Toolbox as well, ) the definition used for $R^2$ instead is  $$ R^2 = \frac{SS_{reg}}{SS_{tot}} $$  where $SS_{reg}$ is the regression sum of squares.   From what I understand, the first definition is the most general one, and it is equivalent to the second definition only in some cases (when $SS_{tot} = SS_{reg} + SS_{res}$, see ). When I calculated the $R^2$ for my linear regression with intercept, the two definitions gave the same result. But when I calculated it for the regression with intercept 0, the results of the two $R^2$ definitions differ. And in my case, if I use the first definition the regression with the intercept is the best fit, with a higher $R^2$, and if I use the second one the 0 intercept is the best fit. If I use Ezyfit, that finds the regression parameters by minimising $SS_{reg}$, it gives me an intercept significantly different from 0, even if the $R^2$ of the 0 intercept is higher according to the definition used inside the toolbox.  I am interested in understanding why Matlab and Ezyfit use the second definition, and in what cases in general it is possible or preferable to use it. In my particular case, which of the two definitions is the more appropriate? Thank you in advance    Edited: I think my question is different than , because there it's R that uses a modified version of $R^2$ if you don't set the intercept, while here I am calculating the $R^2$ myself. From my results, the $R^2$ definitions are equivalent for a fit with intercept, but different without intercept, and I would like to understand why.    Edited (with answer): Thanks everyone. The core of my problem was that the two versions of $R^2$ calculated from me had different results in the case of a linear regression without intercept. This was my mistake, as the second version of $R^2$ . Now I have a different problem, that I'm going to ask in a


How to find $\sum_{i=1}^n\left\lfloor i\sqrt{2}\right\rfloor$ A001951 A Beatty sequence: a(n) = floor(n*sqrt(2)).

[A001951 A Beatty sequence: a(n) = floor(n*sqrt(2)).][1]  If $n = 5$ then  $$\left\lfloor1\sqrt{2}\right\rfloor+ \left\lfloor2\sqrt{2}\right\rfloor + \left\lfloor3\sqrt{2}\right\rfloor +\left\lfloor4 \sqrt{2}\right\rfloor+ \left\lfloor5\sqrt{2}\right\rfloor = 1+2+4+5+7 = 19$$  Sequence from $1$ to $20$ is:  $S=\{1,2,4,5,7,8,9,11,12,14,15,16,18,19,21,22,24,25,26,28\}$  I want to find answer for $10^{100} n$?


How to restore the default toolbox windows in GIMP?

I have recently installed GIMP 2.8.6 on Ubuntu 14.04 LTS 64-bit and for the first time when I opened it, two windows along with the main window were available, but now I can only see a single main window. How can I bring those default windows back?


What does a "CALLBACK" declaration in C do?

I was looking through some code from the  library and came across a function declared like this:  LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)   Now, I'm a Delphi coder.  No hablo C muy bien, senor.  But I remember enough syntax from my college courses to read it like this:  Function name is WndProc.  Argument list is pretty self-explanatory.  Function return type is LRESULT.  But what in the world is that "CALLBACK" doing there?  In Delphi, any function can be used as a callback; you just need to pass the right type of function pointer.  Is there any particular reason why C doesn't work that way?  Or does it mean something different?


bash: /usr/bin/locale-check: No such file or directory error after i downgraded from ubuntu 18.10 to 18.04

After downgrading my Ubuntu from 18.10 to 18.04 when ever trying to login I am getting the following error:    And opening the terminal following error displays      bash: /usr/bin/locale-check: No such file or directory   How can I fix this error?


I'm writing an article about Conway's Game of Life, and I'm using the Springer LNCS template.  In my article, I must sometimes show some game of life patterns, for example the following:    To generate such pattern, I used the Tikz package. The code (without other formatting commands) is the following:  \begin{tikzpicture}   \fill[black] (1,4) rectangle (3,6);   \fill[black] (11,3) rectangle (12,6);   \fill[black] (12,2) rectangle (13,3);   \fill[black] (12,6) rectangle (13,7);   \fill[black] (13,1) rectangle (15,2);   \fill[black] (13,7) rectangle (15,8);   \fill[black] (15,4) rectangle (16,5);   \fill[black] (16,2) rectangle (17,3);   \fill[black] (16,6) rectangle (17,7);   \fill[black] (17,3) rectangle (18,6);   \fill[black] (18,4) rectangle (19,5);   \fill[black] (21,5) rectangle (23,8);   \fill[black] (23,4) rectangle (24,5);   \fill[black] (23,8) rectangle (24,9);   \fill[black] (25,3) rectangle (26,5);   \fill[black] (25,8) rectangle (26,10);   \fill[black] (35,6) rectangle (37,8);   \draw[step=1cm,gray,thick] (0,0) grid (38,11); \end{tikzpicture}   As you can see, this is pretty bad, expecially as I must now produce dozen of such patterns, and manually specifying the coordinates of every black cells is... well, not viable.  The question is: is there a way to achieve the same result as above, but using (for example) a matrix-style input?  What I mean is something like:  \sort-of-matrix-command {     W & W & W & W & W & B \\     W & B & W & W & W & W \\     B & W & B & B & W & W \\     W & W & B & B & B & W \\     B & B & W & W & W & W \\     W & W & W & W & W & W \\ }   where "W" or "B" stand for white cell and black cell respectively.  If it is not possible, any other way which is faster than the one I'm currently using is well accepted.  Thank you in advance!


In my cssh config file, I have:  terminal_font=6x13   this default font is too small for me.   man cssh says, I can specify other font size with the -f argument, while using "standard X font notation".  is a wikipedia page containing some other fonts types. Unfortunately, none of these work for me:  $ cssh host1 host2 -f "7x14" Fatal: Unrecognised font used (7x14). Please amend $HOME/.clusterssh/config with a valid font (see man page).   Why does "7x14" not work?  How can I use bigger fonts with cssh ?


Is there any way in Winter 15 to get access to standard lightning components?  If not thru drag and drop, is there a listing of such components by name and parameters, so that they can be included in a lightning app?


dual boot ubuntu with windows 10 on hp pavillion ab219tx

I bought this new HP laptop which is shipped with windows 10.  so I am thinking to do a dual boot with windows 10 and Ubuntu . can Ubuntu work properly on HP?


How do I make a color background transparent?

How I can make color transparent in Photoshop? For example, I have picture of smoke, and I want to make background color (which is black) transparent. How?


I am a newbie in Ubuntu. I want to use poweroff in my terminal, for traditional shut down of my computer. First of all, is this correct? Secondly, I am forced to use sudo poweroff and then enter a password. Is there a way to make the poweroff command such that, specifically poweroff command will no longer ask for sudo privilege, just commanding poweroff will work.  Thank you for your support


When are we going to get the ability to favourite answers?

Please don't mark this as a dupe until you've read the entire question. Once you have, see  for why it isn't a duplicate.   This question was originally posted on superuser.stackexchange before someone pointed out there was no way to implement such a feature without doing it network-wide, and to post it here instead.    Let me start by saying that this feature strikes me as the single most common sense feature that could currently be implemented onto the network: the vast majority of SE's value comes not from its questions, but from its answers, and questions are just the vehicle that leads to them. Therefore, exceptional answers are far more likely to exist than exceptional questions are, and the vast majority of the time, when users favourite questions, they're doing so not because they want to come back to the question itself, but one of the answers to it.   With this in mind, users across the SE network have been asking for the ability to favourite answers , less than a year after the inception of SO, and     .   Some have even dared to be visionaries and  (i.e. bringing the feature up to speed with the rest of the internet), and others have pointed out that the current implementation has . In short, the best way to summarise users' outlook on these issues would be that, when it comes to the implementation of features that would greatly benefit its users, the SE network seems to have become stagnant, at best.  In this particular case, Jeff Atwood's official answer to this feature request came two years later, a slightly patronising (and heavily censured) response . In the comments to that answer, he provides the only reasoning that:     We believe existing in-browser bookmarking tools are sufficient for this case. Considering the average stack overflow question has maybe 3 answers, tops, the distinction between "I favorite this question" and "I favorite this answer" is minimal. Allowing favoriting answers would also make the interface noisier, and implicitly encourage questions with lots of answers. This isn't going to happen, so either come to terms with the decision, or find another site on the internet that's more to your liking.    Jeff is , so we can live in hope that those currently at the top are less hard-headed about the issue, but that aside, his reasoning given in 2011 is demonstrably outdated: it's now common for questions on the SOFU sites - and even on the slightly less popular sites like English.SE - to attract between 5-10 answers, and for the more popular questions to attract in excess of 30. None of this seems to have been taken into consideration whenever users have asked for the feature to be implemented over the years - instead, these questions are robotically marked as duplicates, citing a 7-year old answer with outdated reasoning given by someone who's no longer involved in SE.  Even if for nothing else than to prove SE isn't determined to let itself stagnate and leave its users behind with the features of a site from the 2010s, when are we going to get the ability to favourite answers?


vertex/object moving sensitivity increases suddenly

After working a while,suddenly if I try to move a vertex or an object, it moves too much.It is like, if I try to move a vertex freely in any direction, it moves .1 unit at a time at first.After working a while it starts to move 1 unit at a time.It does not fix if I hide any object that has too many object on the same project or even if i delete it.What to do?   Same thing happen with rotation and scale.


Why is asymmetric cryptography bad for huge data?

I've been told that asymmetric cryptography requires that the message to be encrypted be smaller than its key length. Why is this?  I know about hybrid encryption, which . But I still want to know why public-key cryptography needs the data to be shorter than the key length.


When I'm trying to update all packages in my environment, using GUI or from terminal by : sudo apt-get update  I get :  It simple says : ... Err:19 http://ppa.launchpad.net/beineri/opt-qt-5.11.1-xenial/ubuntu bionic Release   404  Not Found [IP: 91.189.95.85 80] ...  Using the GUI, I get :  But it exists :


One of my friend told me that photon is massless but I think that (please correct me if i was wrong),  Albert Einstein's equation  $E=mc^2$.  This equation stands for energy,  now as we know energy is also, $E= hc/\lambda$ here h is planck constant and c is speed of light and $\lambda$ is wavelenght of upcoming photons wavelenght so from both equation $mc^2 =hc/\lambda$ solving further $m=h/c\lambda$ hence the photon is not massless.  Tell me where I am wrong.


Can I use Metamagic (or other spellcasting features) on a spell that I gained from multiclassing?

As I understand it, class features only apply to spells you gained through that class. For example, I can't use the Distant Spell metamagic on, say, Cure Wounds, if I gained Cure Wounds from being a Bard. Am I correct in this?  Speaking as both a player and DM here. I wanna know what I can build around.


LaTeX package to insert fancy horizontal lines

I received a pdf written in LaTeX in which I noticed the use of the following horizontal spacer:    Do you know which LaTeX package provides that one?  Thanks a lot, Cheers


If N is a quadratic residue modulo p for all primes p<N, is N a perfect square?

It is known that $N$ is a perfect square if and only if $N$ is a quadratic residue for every prime $p$.  This gives a good probabilistic algorithm for testing if a randomly chosen positive integer is a perfect square - simply compute it's Legendre Symbol for a sufficiently large set of randomly chosen primes.  A single result of $-1$ definitively tells you that $N$ is not a perfect square, while repeated results of only $+1$ or $0$ increase the probability that $N$ is a perfect square.  This probabilistic test could be much quicker with lower probability of a false positive if we could check only primes less than the integer $N$.  The proofs I've seen that $N$ is a perfect square IFF $N$ is a QR mod p for all primes $p$ cannot be used to prove the result using only the finitely many primes less than $N$.    Has anyone seen or know of a proof of this more specific result, or alternatively, know of a counter-example?  I've burned more than a few CPU cycles on Mathematica looking for a counterexample and have not found one yet.


Managed metadata columns in document information panel with multiple content types

the problem I have is that for custom content types not all managed metadata column are displayed in Document Information Panel (DIP) for the document in the Office client application.   However, everything works fine with 1 specific content type. Even though the others using exactly the same site columns. The content types are deployed using visual studio to the content type hub, and after this the content types are correctly published to the site collections.   When I create a document based on the second content type in the same library, all fields are showed in the document information panel, except the managed metadata columns.  Is this a known issue or is there a workaround for this?  Thanks in advance!  Kind regards,  Davy


Windows 10 update removed GRUB menu completely

I keep Ubuntu18.04 and Windows10 in dual boot. After updating the windows10, the GRUB menu to select the OS disappeared.  Things I have tried so far -   Boot repair by logging in system from bootable pen drive -  updating uefi from window by running bcdedit /set {bootmgr} path \EFI\ubuntu\shimx64.efi and restarting. Tried EasyUEFI app ()   "Fast Startup" is disabled on Windows10.  When I clicked on "Install" option while I had boot my system from bootable drive, it was able to detect existing installed Ubuntu18.04 and all the partitions are also there so I am sure it's not uninstalled but I am not able to fix it this time.  I had faced similar issue after past windows10 update but it always got fixed by running bcdedit command. This time nothing seems to work.


I am using OSX 10.7  When I move between different ethernet networks (e.g., at work using ethernet on an external display, at home using thunderbolt ethernet), the ethernet does not always connect. However, I don't get immediate feedback. Instead, I connect to wi-fi. However, wi-fi is both slower and less reliable than ethernet. Thus, I'd like to know whether I am connected to ethernet or not. Of course I can go into preferences and network settings to see whether I'm connected to ethernet, but it would be better if there was some form of indicator in the status bar, just as there is for wi-fi. Thus, my question:  Is there a way of getting an indicator of ethernet connectivity in the OSX menu-bar?  Perhaps there is a free application that can do this.


User top questions list somehow has an invalid question ID

I ran across  who has a fairly prolific SE profile. But I noticed something odd in their list    The question link is as such  https://law.stackexchange.com/questions/-2147481790/34047#34047   A negative question ID? Wait, the first number seems out of place entirely! I went looking and found it's really , so the ID is correct at the end. A rather interesting bug in their profile page.


In this comma-separated expression. Why doesn't the x gets value an instead of b? int main() {  int a=20; int b=100; int x; x=(a,b);  cout<<x; }   Gives output: 100


Each time The Doctor regenerates, there is speculation as to who the actor will be. And each time the speculative lists include both women and non-white actors. However, The Doctor has so far always been played by white male actors.  We already . But is there any in-universe restriction on The Doctor's race?


Analysing a circuit to determine what is in series or in parallel

This is probably a very basic question but I have the following circuit, I am not sure what is in series and what is in parallel or if they are all in parallel, initially I thought R2 and R3 were in series and then used the sum of their resistances with R1 to calculate the equivalent resistance, that seems to be  off based on some circuit simulation software I am using so I would appreciate if somebody could explain how to calculate the Rt and the logic behind it.  Thanks.          – Schematic created using


This is quite confusing!  In the Standard IPA vowel chart, there are /e/ and /ɛ/. See the below picture:    ()  However, many American English vowel charts don't have /e/. So, I think that some English dialects (like General American) don't have /e/, they only have /ɛ/. See the below General American Vowel chart:    ()  In contrast, the British vowel chart has /e/ but doesn't have /ɛ/. See the below Received Pronunciation Vowel chart:    ()  As you can see, the /e/ in British chart is in the position "mid-near front" whereas the /e/ in standard IPA is in the position "close-mid-near front".  The confusing things are in the dictionary. See the word "bed", some American pronounce it as /ˈbɛd/ (), other American dictionaries write it as /bed/ ().  However, most dictionaries pronounce "save" as /seɪv/.  Also, most pronunciation teachers do not teach pronouncing /e/ as a monophthong, but rather they teach pronouncing it as /eɪ/. But it seems English native speakers cannot pronounce or have never pronounced the /e/ in the position "close-mid-near front" as in standard IPA. However, people using other languages can.  So, could you clarify /e/ and /ɛ/?


Correlation between a nominal and ordinal

I would be very grateful if you would tell me how I can find the degree of correlation between a nominal dependent variable and an independent ordinal variable. The nominal variable has only two levels: YES and NO.


Join Modded server without adding the mods

I was just wondering if there is any stuff like mod, plugin, e.t.c or way or even make a modded server and join the it without adding the mod to minecraft folder (%adddata%/.minecraft/mods).


What are the dimensions of a Minecraft Pocket Edition world?

I'm going to build a city and I need to know where the center is. I'm using version 0.6.1. How can I figure out where the exact center is located?


How does current density depend on diameter of wire?

I understand Current density $J =n e  v$ [$n=$ carrier concentration per unit volume, $e=$ charge on electron, $v=$ drift velocity] Which is independent of area of cross section of wire (and hence the diameter) However, the book practical electronics for beginners quotes that:  Current density within a copper wire increase as the diameter of the wire decrease.  Is the book mentioning about varying cross section in the same wire? If yes then can you please explain how does current density increase in a smaller diameter wire?


Do I need a transit visa for a layover in Heathrow?

I am an Indian national. I am travelling from the US to India and my flight has a layover at Heathrow Airort London. The layover time is 5h 45 minutes. Even though I do not intend to leave the airport during this layover, do I still need the transit visa?


At the end of a sentence we place a full stop (or other punctuation). Do we NEED a space after the stop to begin the new sentence?  I have been told it is correct grammar to not use a space after the full stop.


Lorentz transformation in "On the Electrodynamics of Moving Bodies"?

I must be certainly wrong, but there is something I don't understand when reading the paper on "On the Electrodynamics of Moving Bodies" from Albert Einstein. All the sources I found give the same equations as .  I didn't check the original text, but I think a personal error is way more likely than a translation error.  In Chapter 1.3, when deriving the Lorentz transformation from the original assumptions of special relativity, the paper says:     Since tau is a linear function, it follows from these equations that   $$tau=a\left(t-\frac{vx'}{(c^2-v^2)}\right)$$   where $a$ is a function $\phi(v)$ at present unknown, and where for brevity it is assumed that at the origin of $k$, $\tau=0$, when $t=0$ [...]   Then the value of $x'$ being $x'=x-vt$, the paper goes on:      If for x', we substitute its value, we obtain   $$\tau = \phi(v)\beta\left(t-\frac{vx}{c^2}\right)$$   where $\beta=\frac{1}{\sqrt{1-v^2/c^2}}$   But if I do the calculus from the first equation of tau whatever I do I find:  $$\tau = \phi(v)\beta^2(t-(v/c^2)*x)$$  I don't understand. Why do I find $\beta^2$ instead of $\beta$? The calculus looks fairly simple so I don't see where I could have made a mistake. Can someone point me to the derivation of this calculus?  On my part I did like:  $$\tau=a(t-(vx'/(c^2-v^2)))$$  $$\tau=a(t-(v(x-vt)/(c^2-v^2)))$$  $$\tau=a(t(1+v^2/(c^2-v^2))-(vx/(c^2-v^2)))$$  $$\tau = a\beta^2(t-(v/c^2)x)$$


How to evaluate $\int_{0}^{\pi }\theta \ln\tan\frac{\theta }{2} \, \mathrm{d}\theta$

I have some trouble in how to evaluate this integral: $$ \int_{0}^{\pi}\theta\ln\left(\tan\left(\theta \over 2\right)\right) \,\mathrm{d}\theta $$ I think it maybe has another form $$ \int_{0}^{\pi}\theta\ln\left(\tan\left(\theta \over 2\right)\right) \,\mathrm{d}\theta = \sum_{n=1}^{\infty}{1 \over n^{2}} \left[\psi\left(n + {1 \over 2}\right) - \psi\left(1 \over 2\right)\right] $$


What does ? stand for in PHP (after href operator)?

I have the following problem:  I use a template page for a specific application, and for the login through "steam" there is a button. The button refers to a php file, and in the php file you can find the following line of code:
   What does the "?login" exactly mean, I know it stands for a file but I cant find a file named like that, can anyone help me out?


The wedge sum of two circles has fixed point property?   I'm trying to find a continuous map from the wedge sum to itself, that this property fails, I couldn't find it, I need help.  Thanks


Will an 85W power adapter fry the MBP 13" Mid 2009?

, the 60W version of Magsafe is compatible with the MBP 13" Mid 2009. However, I've read that the 85W version is also compatible and leads to faster charge times. I'll keep this short and say, is that correct? Or will it fry my Mac?  P.S - I also read that the 'T style' and 'L style' cords are interchangeable. Could someone please second that?  Thanks


Combinef in R HTS package- constrain to keep forecasts positive?

When using the combinef function from Rob Hyndman's very useful  for forecasting hierarchical and grouped time series, there does not seem to be a way to constrain the optimally combined forecasts to be positive- the starting forecasts can be positive, but can go negative through the reconciliation process.  The forecast.gts and forecast.hts functions have an argument to keep forecasts positive, but this does not seem to be an option when using combinef by itself with forecasts obtained by other methods.  Am I correct in this understanding, and if so is there a decent workaround?


Induction for sum of Poisson distributed random variables

Given the identically distributed and independant random variables $X_1,X_2,\ldots\sim\operatorname{Po}(\lambda)$ and $S_n=X_1+\ldots+X_n$ show with induction that   $$\Pr[S_n=k]=\frac{(n\lambda)^k}{k!}e^{-n\lambda}.$$   So far for $n=1$ via the definition of the density function for Poisson:$$\Pr[S_1=k]=\Pr[X_1=k]=\frac{e^{-\lambda}\lambda^k}{k!}$$ With $n=2$ and independency: $$\Pr[X_1+X_2=k]=\sum\limits_{n=0}^k\Pr[X_1=n]\Pr[X_2=k-n]=\sum\limits_{n=0}^k\frac{\lambda^n}{n!}e^{-\lambda}\frac{\lambda^{k-n}}{(k-n)!}e^{-\lambda}$$$$=\frac{1}{k!}e^{-2\lambda}\sum\limits_{n=0}^k\binom{k}{n}\lambda^n\lambda^{k-n}=\frac{(2\lambda)^k}{k!}e^{-2\lambda}$$ I assume now that with $S_n\sim\operatorname{Po}(\lambda)$ every $X_i\sim\operatorname{Po}(\lambda/n)$ and every Poisson variable can obviously split up, but how can I prove this?


What are the advantages of Ubuntu 16.04 over Ubuntu 14.04?

I have been using Ubuntu 14.04 as my main OS for about two years now. I wonder what are the advantages of the new LTS version (i.e. 16.04) so I can decide whether I should upgrade or not.


I have a small issue with my Ubuntu (I think After an upgarde). When I try to login (Login Screen), I get disconnected and get back to the screen (again & again).  I tried:   Trying to login with others Desktop environements. Booting from old kernel. log in via command line [apt-get update && apt-get upgrade]. removing ~/.gconf directory. sudo apt-get install --reinstall ubuntu-desktop and sudo apt-get install unity   None of these solutions worked.


I have a 20-room house that is close to a 'spawn corruption'. Only 6/20 rooms were taken.  NPCs are not spawning, like the guide, nurse, and tax collector.  Is it because my house is too close to corruption or something else?


Why is the preview render slower than the final render?

Firstly, sorry if that's a stupid question. I'm kinda noob :P The thing is that "normal" rendering with GPU is slower than rendering in preview. I made sure that the resolution in which I render is the same as in the preview but it's still slower as if it was rendered with CPU.


Let $A$ and $B$ be $n \times n$ real matrices such that  $A^2 = I, B^2 = I$ and $(AB)^2 = I$.  Prove that $AB = BA$.  Someone help me with this problem


Energy saving measures in Ubuntu desktop computers / PCs

What tools or measures are available for saving energy in desktop computers / PCs?  Is there an easy way to switch between GUI and CLI that really stops and starts GUI to minimise the power consumption of graphics card whenever GUI is not required?


Dagor Dagorath - Is there any indication of who may return?

As you know, this is the apocolyptic event which occurs at the end of LOTR. I've been searching non-stop but simply cannot find if any from say, War of the Ring will return. People like Gandalf, The Witch King. I know Sauron and Morgoth and the other Valar do, but It's more the likes of say Saruman. He specifically confuses me. Would they make use of Saruman? Would he be brought back? What confuses me about him though is, who would he serve? Morgoth or Manwe?


In the game Threes (on Android), there is a "Special Thanks" section with a swipe to see more message at the bottom.  There's a potential cryptic message "somewhat hidden there.    Does anyone know if it means something?


Shiny Materials Not Showing Up In Render

Ok so Blender was working perfectly fine for months now until today I tried to render a weapon with a chrome material, only to find out that it rendered without the material! I already tried resetting Blender to all default settings and I've quadruple checked to be sure non of the objects are hidden. Yes, the lighting is very bright too, but that doesn't show either. See pictures below.  (Edit): Guys, I'm not stupid. I already tried the background idea. I looked around for an hour for solutions before posting this question and found a few people having the same problem, (including the thread that this is a "duplicate" of) but none of the suggestions people gave them fixed my problem. Even if there is no background, the object should at least be interacting with the light somewhat. Example:     That's a render I made the week before I started having issues, I'm not very proud of it but it proves my point. So what's below doesn't make any sense.    Even with a different color.    But when I use a dryer, non glossy material like leather or just the default diffuse mat everything shows up fine.    Plz help ;__;


Say I am hashing hashes (taking the hash of a previous hash) for an endless amount of time.  How many times would it take, on average, to fall into a loop when using SHA-2 (more specifically SHA-256 and SHA-512), like such:  original text = z (can be any string) hash z = b hash b = c hash c = d  ...  hash n = b (restarting loop)   or more literally,  original text = "test" SHA-256 of "test" = "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08" SHA-256 of "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08" = "7b3d979ca8330a94fa7e9e1b466d8b99e0bcdea1ec90596c0dcc8d7ef6b4300c"  ...  SHA-256 of n = SHA-256 of "test" = "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"   How many attempts, on average, would this take?


No new line in terminal ubuntu after changing prompt style

I changed the PS1 for terminal to   export PS1="\033[0;33m\h:\W \u\$ \e[m"   Now, it doesn't type into new lines in case of a long sentence. Instead, it just overwrites on the existing written stuff in the same line.   Am I missing something ?


How can I show that a bijection between $[0,1)$ and $(0,1)$ cannot be continuous?

Suppose $f:[0,1)\to (0,1)$ is bijective. Prove that $f$ is not continuous.     I know that $(0,1)$ and $[0,1)$ are not homeomorphic spaces because of the connected property. Can we then conclude that $f$ is not continuous because of that?


Best graphics driver for HP Laptop with Switchable Graphics?

I'm planning to dual boot my laptop with Windows 7 and Ubuntu 13.10. I'm using an HP Pavilion DV6-6140tx laptop, which is packed with AMD 6770M 1GB GPU. For windows, I'm using a third party AMD CCC driver and it works like charm and GPU switching happens butter smooth. I just want to know where I can find the best driver for Ubuntu(for my laptop) ?


bug with page numbers when using soul package

I recently ran into a curious bug when using the soul package. I managed to boil it down to the following example. The problem is that the page numbers get messed up. In the example below, they should be 1, 2 and 3. In fact, they are 1, 0 , and 1, in that order. It appears (in some cases) that adding blank lines inside a \hl environment sometimes causes this problem, and removing the blank lines fixes the problem. As one can check, removing the blank line inside the \hl{} fixes the problem in the example below. It is also possible to fix the problem in other ways.  Anyway, now that I have discovered this, I can work around the problem in my paper. However, I'm curious as to what is causing this, so I thought I might as well post the question. I didn't try asking the creator ofsoul, which I think is probably unmaintained. The last update was a long time ago. This is with Debian squeeze, using TeX Live 2009 and soul.sty version 2.4.  I'm using the LaTex function dummytext below to generate dummy data courtesy of the kind folks on this site, see  The specific solution I'm using is by .  \documentclass[10pt]{article} \usepackage{soul} \usepackage{pgffor} \usepackage{setspace} \doublespacing \newcommand\dummytext[3]{%     \foreach \n in {1,...,#3} {%         \foreach \k in {1,...,#2} {%             #1%         }%         \\     }% } \pagestyle{myheadings} \begin{document} \dummytext{HelloWorld}{5}{52}  \dummytext{HelloWorld}{5}{17} \hl{  x } \end{document}


Does a ball, when thrown into the air, ever experience an instant of rest?

Say I walk outside and throw a ball into the air. Obviously it will decelerate as it travels upward due to Earth's gravity, and accelerate as it travels downward for the same reason. But is the ball ever at rest -- say, for even a nanosecond -- between the period of time when it is traveling upward and the period of time when it is travelling downward? Or is the ball either going up or down -- and only up or down -- at any given instance? If so, how does it make the transition from travelling upward to travelling downward?


Building a bijection from a finite union of countable sets to $\mathbb{N}$

Let $A_1,...A_k$ be countable sets, I need to prove that the union $\bigcup_{i=1}^{k}A_i$ is countable by explicitly building a surjection.  I can't assume that the sets are disjoint.  I can easily build an injection $g:\bigcup_{i=1}^{k}A_i\rightarrow \mathbb{N}\times\mathbb{N}$ by defining $g(a)=(f_{i}(a),i)$ where $f_i$ is the first bijection from the bijections $f_i,...f_k$ that maps $A_i\rightarrow\mathbb{N}$ such that $a\in A_i$.  However, this map $g$ obviously isn't surjective.  Any ideas for building such map?


What is the cause of centripetal/centrifugal force?

What is the cause of / force? When an object of mass $m$ is moved in a circular orbit, it experiences a centrifugal force radially away from the center. What is the cause of this centrifugal force? Is these related to the four fundamental forces (gravity,electromagnetic,weak and strong forces)?  This force is equivalent to a force experienced while stopping a mass in motion (Inertia).  But is this inertia caused by some force? or what causes inertia? A photon particle does not have inertia of rest.


Is the trio's Polyjuice escapade in Chamber of Secrets ever discovered?

In HP and the Chamber of Secrets, Harry, Ron, and Hermione  by brewing Polyjuice Potion and drugging and impersonating other students, just in order to get into the Slytherin common room and probe Malfoy for information about the Chamber of Secrets.  Is this little adventure ever discovered by Those in Charge (teachers)? Or even by Malfoy?  If so, did they ever get punished? I can't see how they could fairly have avoided it (other than they're the Golden Trio and always do). In the end they don't actually get any useful information, except that Malfoy isn't the culprit. This escapade doesn't help them at all in their eventual discovery of the culprit and destruction of the Basilisk. It was just motivated by their suspicion of Malfoy, which was essentially based on "he's Slytherin and we don't like him" and turned out to be unfounded.  If not, how could it remain undetected? Hermione's skill with Polyjuice Potion is eventually common knowledge ... more importantly, why didn't Crabbe and Goyle run to tell someone when they woke up and found they'd been drugged? Did the topic never come up between Malfoy and the pair of them, with Malfoy realising he'd been talking to impostors? What did they tell Madam Pomfrey about Hermione's semifelinity after her failed attempt to Polyjuice herself into Millicent Bulstrode?


How to prove that $U_{2^n}$ is isomorphic as group to $\mathbb Z_2 \times \mathbb Z_{2^{n-2}}$ for $n \ge 3$?

How to prove that $U_{2^n}$ is isomorphic as group to $\mathbb Z_2 \times \mathbb Z_{2^{n-2}}$ for $n \ge 3$ ?


Regex - return match between strings in template literals

I want to match all strings between custom string, so here we go:  var string = `      <!--@hello-dear:John-->     <h1>John</h1>     <!--@bye-dear:John-->  `;  var startString = ""; var endString   = "";  var regString = startString + "(.*?)" + endString; var regex     = new RegExp(regString, "i");  console.log(string.match(regex));   Returns null  Expected that matched object with the string  "
John
 "


Is there a free subgroup of rank 3 in $SO_3$?

There are known free subgroups of rank 2 in the set of rotations about the origin in $\mathbb{R}^3$, $SO_3$.  For instance, the rotations by angle $\arccos \frac {1}{3}$ about the $z$- and $x$-axis generate such a free subgroup.  Are there free subgroups of rank 3 (or higher) in $SO_3$?


Getting weird stuff in render & Solid view regardless of material

Just loaded up after months of not touching blender. And I can't get rid of the weird shadow in the middle of the object or get materials to display. To be clear this only happens in Eevee while everything is normal in cycles. This is affecting both basic shapes I'm adding in & old blend files that would display their materials properly. Feel like I'm missing something basic but I could also swear it never used to be like this.


I want to install Ubuntu for first time. if I install ubuntu alongside Window 7 or 8 there will be no problem ?