If I have a symmetric group on $9$ letters, how many elements in the group have order $7$?  I’ve started off thinking about the disjoint cycles, so in cyclic form the only elements can be $7,1,1$ to get order $7$ (as sum of cycles has to equal $9$ but lcm has to equal $7$).  So I started to think about permutations of it. And I’m stuck there.

I need to find how many elements of order $k$ are in $S_n$ (where $k \leq n$).   So if $k$ is prime, it's easy: $k$ can't be the $\mathrm{lcm}$ of any integers besides itself and one's (which we're omitting). So the length of the cycle then must be $k$, and the number of elements with $k$-length cycle representation in $S_n$ is given by $$\dbinom{n}{k}(k-1)!$$ But it gets really tricky when $k$ is not a prime number... I need to consider every set of integers that can divide $k$, and then, for every set, I need to find how many elements of that form are there... Or maybe I'm missing something here?  I need help figuring that out. thanks in advanced!


I have this generator which returns a list of numbers.  li=tile_generator(im)   I need to find the length of the list "li" as I need to check for a threshold value. I used length = sum(1 for i in li). It is returning the length of the list but the elements in the generator are exhausted as it is a generator. I need to return the length without exhausting the elements in the generator.

Python provides a nice method for getting length of an eager iterable, len(x) that is. But I couldn't find anything similar for lazy iterables represented by generator comprehensions and functions. Of course, it is not hard to write something like:  def iterlen(x):   n = 0   try:     while True:       next(x)       n += 1   except StopIteration: pass   return n   But I can't get rid of a feeling that I'm reimplementing a bicycle.  (While I was typing the function, a thought struck my mind: maybe there really is no such function, because it "destroys" its argument. Not an issue for my case, though).  P.S.: concerning the first answers - yes, something like len(list(x)) would work too, but that drastically increases the usage of memory.  P.P.S.: re-checked... Disregard the P.S., seems I made a mistake while trying that, it works fine. Sorry for the trouble.


We have a raspberry pi system that needs to be able to remotely re-image itself, if the image becomes corrupted or on demand. How do I go about doing this?  Also, how do I setup a pi that wasn't originally configured to do this?  The OS I am using is Raspbin, also device is 4 hours drive away. So physically changing the SD card is a no go.

I have a Raspberry Pi and I need to get the image reinstalled but it's a 4 hour drive away to it. The OS is Raspbian and it is connected through an Ethernet connection. I can SSH into the Raspberry Pi just fine, but I need to find a way to remotely reinstall the OS on it.  I hear there is something called PXE Network Install that might be able to do this, but how would I go about doing this? The website doesn't really have much information on doing this.


I went today to the swimming pool and I remembered that when I was younger my mom used to tell me to be careful because you get sunburnt much more easily in the water than in the ground.  I never gave this a lot of thought until recently and I consider that it might be caused by two factors: the reflection and refraction of sun rays in the water and the loss of efficacy of your sunscreen produced by the water (even if it is water resistant).  Is the first effect actually relevant? It should be possible to compare the flux of energy due to reflected rays to that compared of direct rays.  Do we get sunburnt more easily because of the reflection? In case this is the case I would like to know if there is any difference between the effect in a swimming pool or in the sea.

There is a popular belief that wet skin burns or tans faster. However, I've never heard a believable explanation of why this happens.  The best explanation I've heard is that the water droplets on the skin act as a lens, focusing the sunlight onto your skin. I don't see how this would affect an overall burn, because the amount of sunlight reaching the skin is the same (ignoring reflection).  Is this 'fact' true, and if so, what causes it?


Is it possible to monitor/view the response codes of traffic to a server with HTTPS? I can use ngrep or tcpdump to view HTTP (port 80) but this won't work for HTTPS (port 443) requests - they simply don't show up.  For example, I'd like to test if web pages that googlebot is requesting are responding with 500 error codes, so that I can track down problems with googlebot not being able to access my pages.  I'm thinking maybe something like WireShark could do it, but I have no idea where to begin with a tool like that, and I'm not sure it can see the response codes since HTTPS is encrypted?

I'm really new to managing servers, and I've discovered that I can run ngrep and see connections from Google to our site (which is currently getting thousands upon thousands of 5xx errors and "crawl anomaly" errors in search console).  My question is how can I see if the connections are successful (if google is actually receiving a 200 response code, or not). Also, does Connection: close. mean that the connection was closed and they did not receive a response?   Example of output from ngrep.  $ sudo ngrep -il -d eth0 -W byline "Chrome/41.0.2272.96 Mobile Safari/537.36" port 80  GET / HTTP/1.1. Host: subdomain.com.example.com. User-Agent: Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.96 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) X-Middleton/1. Accept: text/html,application/xhtml+xml,application/signed-exchange;v=b3,application/xml;q=0.9,*/*;q=0.8. Amp-Cache-Transform: google;v="1..3". Cookie: BLAH. From: googlebot(at)googlebot.com. If-Modified-Since: Mon, 04 May 2020 15:51:07 GMT. X-Forwarded-For: IP, IP. X-Middleton: 1. X-Middleton-Ip: IP. X-Real-Ip: IP. X-Snipe: BLAH. Accept-Encoding: gzip. Connection: close.


It is a C question as says the title.  I have a function named "net_send" defined in two different header files. Here is the example:  f1.h and f2.h both contain net_send(args) but with different arguments.  I get an error that the function is already defined in alternate file. I know function overloading is not allowed in C. Also, I cannot edit those files, as these are from external libraries. Also, there are functions in each of those files which are being used by my program itself.  So what should I do? Remember I cannot change the original files.

What should I do if I have two libraries that provide functions with equivalent names?


I heard people saying something like this:     We have to "rescrew" [e.g.] a tissue box holster to the wall.   I'm not sure, is the syllable "re" common? It seems this is not too commonly used.  What are possible synonyms / more common terms?

Can all verbs have "re" attached to the front of the word? I play Scrabble with a friend who feels that in the English language you can put "re" in front on any verb, and not just the ones listed in the dictionary.


I know, questions like this have been asked before, but I'd like to get some up to date experiences.. From what I've read in various discussions, BTRFS seems like it's relatively stable, but once in a lifetime, with some kind of an upgrade it breaks (don't know how old this info is...). I'm sure, many of you are using BTRFS right now and I'd like to switch to it too, I'd just like to know if YOU consider it stable, had any problems with it, and, well, would you trust it to handle your.... let's say semester project?

I see entries describing BTRFS on Ubuntu 12.04 has some concerns due mostly to the maturity of the BTRFS product.  Now that we have 13.10 available, is the BTRFS file system reliable?


I have a residence and work permit for Denmark and since I'm flying there for the first time, my passport has not been stamped. Do I need a transit visa if I'm travelling through Finland (since it's in Schengen area), if that is going to be my first port of entry?  Also, does the same apply for a layover in any other Schengen country?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


I am running windows 7. I have a 2GB flash-drive running a strawberry Perl portable edition. I was spending time installing CPAN modules this morning when suddenly my disk became write protected. Unfortunately, I cant do anything to diagnose because it is write only. I cant even reformat. The drive was washed accidentally, but that was months ago. Did perl do this to me, or is it just my flashdrive?  note: I do NOT have a write protection switch.

When I plug in my USB flash drive, it shows up on my computer as write-protected or read-only. I am unable to transfer data to it, nor can I modify or delete any files already stored on it. I also cannot repartition or reformat the drive using Windows Disk Management, DiskPart, GParted, or other tools. The drive does not have a write-protect switch.  Why did this happen and what can I do about it? Is there a way to remove the write protection?  (Note that this can happen with some memory cards, too, as they often use controllers similar to those used in flash drives. In some cases, the system may report that the drive or card was formatted successfully even though it was never actually formatted; the original data reappears when the device is reinserted.)     This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details.


Let $A$ and $B$ be two events such that $P((A \space $U$ \space B)^c) = 0.6$ and $P(A \cap B) = 0.1$. Let $E$ be the event that either $A$ or $B$ but not both will occur. Find $P(E \mid A \space $U$ \space B)$. What I have tried: $P((A \space $U$\space B)^c) = 0.6 = 1-P(A \space $U$\space B) \space$. Therefore, $\space P(A \space $U$ \space B) = 0.4$. For either event $A$ or $B$ to occur and not both, we have $$E = P(A\cap B^c)\cup P(A^c\cap B)$$ So we now have: $$\begin{align} P(E \mid A\cup B) &= \frac{P((A\cap B^c)\cup (A^c\cap B))\cap P(A\cup B)}{P(A \cup B)} \\ &= \frac{P((A\cap B^c)\cup (A^c\cap B))\cap 0.4}{0.4} \end{align}$$ I'm not sure how to get $P(A)$ from $P(A^c\cap B)$ when $P(A^c\cap B) = P(A) - P(A\cap B)$.

I'm self-studying a textbook () (not for course credit) and wanted to post my solution to a problem related to conditional probability.   Given:  $$ \begin{align} &P((A \cup B)^C) = 0.6 \\ &P(A \cap B) = 0.1 \\ &E = A\ xor\ B\ \text{(A or B but not both)} \end{align} $$  Find $P(E\ |\ A \cup B)$  Below is my solution. Is this correct or else where did I go wrong?   $$ \begin{align} P(E\ |\ A \cup B) &= \frac{P(E\ \cap\ (A \cup B))}{P(A \cup B)} \tag 1 \\  \\ P(E\ \cap (A \cup B)) &= P((E \cap A)\ \cup\ (E \cap B)) \tag 2 \\ \\ &= P((A \cup B) \cup (A \cup B)) \\ \\ &= P(A \cup B) \\ \\ \therefore \\ \\ P(E\ |\ A \cup B) &= \frac{P(A \cup B)}{P(A \cup B)} = 1 \tag 3 \\ \\ \end{align} $$  Noting that $E \cap B$ = [(A xor B) or B] = $A \cup B$ and similarly $E \cap A$ = [(A xor B) or A] = $A \cup B$.


Let $G$ be a group such that ${\rm Aut}(G) = 1.$ I know that $G$ is abelian and that every element of $G$ satisfies the equation $x^2 = 1.$ This can be shown by considering the mapping $x \mapsto x^{-1}$ which is an automorphism. I want to show that the order of $G$ is $1$ or $2.$ Is it sufficient to note that since $G$ is abelian and every element of $G$ satisfies $x^2 = 1$, then $G$ has non-identity automorphism if the group contains more than two elements? I was wondering if this would suffice or do we need to prove this more rigorously?

Let $G$ be a finite group with $|G|>2$. Prove that ${\rm Aut}(G)$ contains at least two elements.  We know that ${\rm Aut}(G)$ contains the identity function $f: G \to G: x \mapsto x$. If $G$ is non-abelian, look at $g : G \to G: x \mapsto gxg^{-1}$, for $g\neq e$. This is an inner automorphism unequal to the identity function, so we have at least two elements in ${\rm Aut}(G).$ Now assume $G$ is abelian. Then the only inner automorphism is the identity function. Now look at the mapping $\varphi: G \to G : x \mapsto x^{-1}$. This is an homomorphism because $\varphi (xy) = (xy)^{-1} = y^{-1} x^{-1} = x^{-1} y^{-1} = \varphi (x) \varphi (y)$. Here we use the fact that $G$ is abelian. This mapping is clearly bijective, and thus an automorphism. This automorphism is unequal to the identity function only if there exists an element $x \in G$ such that $x \neq x^{-1}$. In other words, there must be an element of order greater than $2$. Now assume $G$ is abelian and every non-identity element has order $2$. By Cauchy's theorem we know that the group must have order $2^n$. I got stuck at this point. I've looked at this other post, , but I don't know what they do in the last part (when they start talking about vector spaces). How should this prove be finished, without resorting to vector spaces if possible? Thanks in advance


I am planning a visit to London. I was wondering what are the optimum choices to exchange euros to pounds and pounds to euros?  Is there an extra charge, apart from the exchange rate?  Is it safe to do it in Heathrow?  For a 2 day stay, eating finger food, not drinking and not spending a lot of money(except some cheap street souvenirs) what is fair amount of money to be needed?

Recently my wife and I traveled to Italy and before we left we got about 85% of our money in travelers checks and the other 15% we carried on in cash. When we arrived there, no one would take our travelers checks and many places did not accept credit cards. Eventually, we found some currency exchange places that would take the travelers checks and give us Euro's, but at a 7-15% fee, which was not really a very fun surprise.   While I was under the impression that it is safer to use travelers checks, it seems that they were not really accepted (the usual explanation being fraud). So the question is, is it best to just exchange your currency at home and carry all of it with you when you travel or are there other alternatives to carrying cash that are safer and cost effective?


I would like to force latex enumerate environment to output (1), (2),... in place of 1., 2. that he gives by default. How could I do this ?  I don't need to do it in my whole document but in some places only. Hence I should only make modifications in the chosen enumerate environment.

I've seen documentation whereby an \alph command is put around the \begin{enumerate} somewhere, but I'm not entirely sure how that operates...


In the following series:  $ \displaystyle\sum\limits_{n=1}^{\infty}n*\frac{1}{2^n}$  I've found that the series converges to 2 by looking it up but how would one calculate the summation? You can't use the formula for a geometric sum because the series' terms don't differ by a common ratio. I'm sure I'm just missing something but it's been a while since I've done series. Thanks!

I have put his on wolfram and obtained answer as follows:  $\sum_{n=1}^{\infty}\frac{n}{2^n} = 2$  And the series is convergent too because $\lim_{n\to\infty} \frac {n}{2^n} = 0$  However I am wondering if there is a convenient way to solve this; I don't think you can represent it by a geometric progression either. So how do we have to do it on paper?


I have started  la ~   with the output  ls: cannot access .gvfs: Permission denied   I've done quite a bit of googling but haven't found a solution. Any ideas what is wrong?

Whenever I run an application in terminal as root (such as sudo gedit  /etc/default/varnish) , subsequently when I open another terminal I get "ls: cannot access .gvfs: Permission denied" error at top line of terminal.   I found a solution on the net     umount /path/to/.gvfs   rm -rf .gvfs   but it only fixes problem temporarily.  It appears that I have two mounted instances of gvfs in my system    $ sudo mount |grep gvfs     gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=33)     gvfsd-fuse on /home/****/.gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=0,group_id=0)   I don't know if it's related to, a few months ago I had to change permission in my home folder like     sudo chown -R $USER:www-data   Would you please help me fix it?  EDIT: After I unmount /run/user/1000/gvfs I don't get that error.


I've been looking into Serializing Objects so that I can send Objects through networking easily and quickly. There's one big Issue in this though. After I initialize a value in my array, the serialized Object for that array will always stay as the initialized number. I'm not even sure if this is the case as I'm pretty sure ints have a default value of 0. So wouldn't it stay as 0 instead of what I change it to?  public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {     FileOutputStream ostr = new FileOutputStream(new File("ObjectFile.yeh"));     FileInputStream istr = new FileInputStream(new File("ObjectFile.yeh"));     ObjectOutputStream out= new ObjectOutputStream(ostr);     int[] hi = new int[5];     hi[0]=3;     out.writeUTF("This is an Array");     out.writeObject(hi);     hi[0]=5;     out.writeObject(hi);     out.writeUTF("Array Over");     out.close();     ObjectInputStream in = new ObjectInputStream(istr);     System.out.println(in.readUTF());     int[] h = (int[]) in.readObject();     System.out.println(h[0]);     int[] j = (int[]) in.readObject();     System.out.println(j[0]);     System.out.println(in.readUTF());     in.close(); }   When I run the following code it prints  This is an Array 3 3 Array Over   How should I solve this problem?  Update:  After further experimentation I found that after an Object is Serialized once, it's serial doesn't seem to change. As shown here I edit the String array and it's contents don't change after being sent through the Object Stream      public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {     FileOutputStream ostr = new FileOutputStream(new File("ObjectFile.yeh"));     FileInputStream istr = new FileInputStream(new File("ObjectFile.yeh"));     ObjectOutputStream out= new ObjectOutputStream(ostr);     String[] hi = new String[5];     hi[0]="Hi";     out.writeUTF("This is an Array");     out.writeObject(hi);     hi[0]="Hello";     hi[1]="Hoopla";     out.writeObject(hi);     out.writeUTF("Array Over");     out.close();     ObjectInputStream in = new ObjectInputStream(istr);     System.out.println(in.readUTF());     String[] h = (String[]) in.readObject();     System.out.println(h[0]+" "+h[1]);     String[] j = (String[]) in.readObject();     System.out.println(j[0]+" "+j[1]);     System.out.println(in.readUTF());     in.close(); }   And this prints  This is an Array Hi null Hi null Array Over

I have the following code that shows either a bug or a misunderstanding on my part.  I sent the same list, but modified over an ObjectOutputStream.  Once as [0] and other as [1].  But when I read it, I get [0] twice.  I think this is caused by the fact that I am sending over the same object and ObjectOutputStream must be caching them somehow.  Is this work as it should, or should I file a bug?   import java.io.*; import java.net.*; import java.util.*;  public class OOS {      public static void main(String[] args) throws Exception {         Thread t1 = new Thread(new Runnable() {             public void run() {                 try {                     ServerSocket ss = new ServerSocket(12344);                     Socket s= ss.accept();                      ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());                     List same = new ArrayList();                     same.add(0);                     oos.writeObject(same);                     same.clear();                     same.add(1);                     oos.writeObject(same);                  } catch(Exception e) {                     e.printStackTrace();                 }             }         });         t1.start();          Socket s = new Socket("localhost", 12344);         ObjectInputStream ois = new ObjectInputStream(s.getInputStream());          // outputs [0] as expected         System.out.println(ois.readObject());          // outputs [0], but expected [1]         System.out.println(ois.readObject());         System.exit(0);     } }


Is $x^4+x^2+1$ an irreducible polynomial over $\Bbb Z/2\Bbb Z$?   According to  the answer is no. But I can't find the factors. Can you?

Let $\mathbb{F}_2 \cong \mathbb{Z}/2\mathbb{Z}$ denote the field of 2 elements   (a) Is $x^4+x^2+1$ irreducible in $\mathbb{F}_2[x]$? Find a complete factorization.  (b) How many irreducible polynomials of degree 4 are there in $\mathbb{F}_2[x]$?  For the first part of the problem, I just plug in $0$ and $1$ into $x^4+x^2+1$, and know that there is no root for that polynomial, so this polynomial is irreducible.   For the second part, I just list polynomials of degree 4 and having no zero in $\mathbb{F}_2[x]$, which are $x^4 + x+1, x^4 +x^2 +1, x^4 + x^3 +1$ , and $x^4 + x^3 +x^2 + x +1$.   But I am not sure about whether these approaches are right, so could you help me to figure it out? Thank you!


In  you will notice a ring of intersection points, all circling the focal land mass of the map. What are these intersections used for? I assume they are meant to guide the cartographer, but how do they work? What determines how the intersections of lines are placed?

Many old maps have lines like below. Is there a term for a map with that type of lines?   (from )  My best hypothesis is that the lines may be related to  and therefore Mercator projections.  .


I have come upon with the following problem: Let $M$ be an $A$-module (assume that $A$ is commutative with identity) which is both free and finitely-generated. My question is whether there is an elementary way to prove that $M$ is isomorphic to the free finitely-generated $A$-module $A^{n}$, for some $n\in\mathbb{Z}_{\geq 0}$. Here is a proof using tensor-products: First, since $M$ is free, we have an isomorphism $M\cong \bigoplus_{I}A$ for a set $I$. Then, since it is finitely-generated, say by $x_{1},\dots,x_{n}$, we get a surjective map $\phi:A^{n}\twoheadrightarrow M\cong \bigoplus_{I}A$ (sending each basis vector $e_{i}$ to the generator $x_{i}$). Let then $\mathfrak{m}\subseteq A$ be maximal ideal and consider the field $k=A/\mathfrak{m}$ which is an $A$-module. Then, since tensoring is right-exact, we have that the induced map $\phi\otimes\mathrm{id}_{k}:A^{n}\otimes_{A}k\to (\bigoplus_{I}A)\otimes_{A}k$ is surjective. Now, as tensor product commutes (distributes) naturally with direct sums we have a commutative square: $\require{AMScd}$ \begin{CD} A^{n}\otimes_{A}k @>{\phi\otimes\mathrm{id}_{k}}>> \left(\bigoplus_{I}A\right)\otimes_{A}k\\ @VVV @VVV\\ k^{n} @>{\psi}>> \bigoplus_{I}k \end{CD} where the vertical arrows are isomorphisms. Thus, $\psi:k^{n}\to \bigoplus_{I}k$ is a surjective map of $k$-vector spaces and so $n\geq |I|$, as desired. I am wondering though if there is a more elementary proof, e.g. by using the basis explicitly.

Say I have a module $M$ over a ring $R$ that is   $1.$ finitely-generated, i.e. $\exists$ finite $X \subset M$ such that $M = \sum_{i=1}^{n} Rx_{i}, x_{i}\in X$ (but $X$ is not necessarily free)  $2.$ free, i.e. $\exists$ a basis $Y \subset M$ a.k.a. $Y$ is free and generates M, (but $Y$ is not necessarily finite).  Now I want to show, that there exists a finite basis for $M$. For vector spaces, this would obviously be trivial, but for some  $R$-Modul, I'm not sure how to proceed.   Furthermore, is every minimal generating subset of $M$ a basis?


I create a tree using node/child in tikz as follows.  \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \tikzstyle{nodestyle} = [circle,draw,minimum size=5pt]  \node [nodestyle, inner sep=0pt] {$A|_{\aleph_0}$} child {node {$\vdots$}     child {node [nodestyle, inner sep=4pt] (b1) {$S$}         child {node [nodestyle,inner sep=0pt] {$\{X_1\}$}             child {node [nodestyle, inner sep=1pt] {$X_1$}}}         child {node [nodestyle,inner sep=1pt] (e) {$X_2$}}} } child {node {$\vdots$} child {node [nodestyle, inner sep=2pt] (b3) {$X_1$}}} child {node {$\cdots\cdots$}} child {node {$\vdots$} child {node [nodestyle, inner sep=2pt] (an) {$X_n$}} };  \end{tikzpicture} \end{document}   Now I want to remove the branch above \cdots in child. How do I do it? Thanks.

I want to draw a tree and not draw specific edges. I try it like this   \documentclass[preview]{standalone} \usepackage{tikz}  \begin{document}    \begin{tikzpicture}[every node/.style={circle,draw}]       \node (r) {$r$}       child { node (T1) {$T_1$} }       child { edge from parent[draw=none] node[draw=none] (ellipsis) {$\ldots$} }       child { node (Tn) {$T_n$} };    \end{tikzpicture} \end{document}   This does drop the edge of the middle child, but for some reason shifts the node upwards. I want it to be placed at the same level as its siblings.  Is this doable without manually drawing a node between (T1) and (Tn)?


I just installed gparted because I have a 135 GB flash drive that I want to use for bootables for different OSs.   After I installed gparted and opened it from the Dash, I got the prompt for my password, entered it, the window closed, cursor turned to the loading symbol, I waited, the cursor went back to normal, that was it.  I installed it with sudo apt-get install gparted.  The output from gksudo gparted is  Error copying '/home/amolith/.Xauthority' to '/tmp/libgksu-k9KFpI': No such file or directory   The output from gparted-pkexec is  Created symlink /run/systemd/system/-.mount → /dev/null. Created symlink /run/systemd/system/boot.mount → /dev/null. Created symlink /run/systemd/system/run-user-1000.mount → /dev/null. Created symlink /run/systemd/system/run-user-120.mount → /dev/null. Created symlink /run/systemd/system/snap-core-2381.mount → /dev/null.   Created symlink /run/systemd/system/tmp.mount → /dev/null. No protocol specified  (gpartedbin:6347): Gtk-WARNING **: cannot open display: :0 Removed /run/systemd/system/-.mount. Removed /run/systemd/system/boot.mount. Removed /run/systemd/system/run-user-1000.mount. Removed /run/systemd/system/run-user-120.mount. Removed /run/systemd/system/snap-core-2381.mount. Removed /run/systemd/system/tmp.mount.   Any help would be greatly appreciated.

I installed Ubuntu 17.10. Now I am having trouble with gksu:  $ gksu -dg synaptic No ask_pass set, using default! xauth: /tmp/libgksu-HgUjgQ/.Xauthority STARTUP_ID: gksu/synaptic/8760-0-alex-XPS-15-9530_TIME4974977 cmd[0]: /usr/bin/sudo cmd[1]: -H cmd[2]: -S cmd[3]: -p cmd[4]: GNOME_SUDO_PASS cmd[5]: -u cmd[6]: root cmd[7]: -- cmd[8]: synaptic buffer: -GNOME_SUDO_PASS- brute force GNOME_SUDO_PASS ended... Yeah, we're in... Unable to init server: Could not connect: Connection refused (synaptic:8767): Gtk-WARNING **: cannot open display: :1 xauth: /tmp/libgksu-HgUjgQ/.Xauthority xauth_env: (null) dir: /tmp/libgksu-HgUjgQ   If I don't use -g, the password dialog is disabled. So looks like a problem with creating a tty for root.  Any advice?


I'm not complaining but I suspect a bug. I've been awarded the Yearling badge 3 times now in the last two days. Is it a bug?

Formerly List of all badges with full descriptions.  What are badge name's requirements? Why didn't I get badge name ? Which badges can I earn multiple times?    Jump to:                    Note: Some badges are awarded based on score. The term score means the total number of upvotes minus the total number of downvotes.  Any badge with a *** next to it is one of 20 badges that count towards the  displayed on a moderator candidate in an election. The candidate score is a total of 40 points: the first 20 are awarded based on the user's rep divided by 1000 and rounded down; the second 20 represents the total number of unique badges earned of the 20 that count. Note that if the same badge is earned multiple times, it will only count once towards the candidate score.  Any badge with a "(retired)" next to it is no longer awarded, but is retained by users who previously earned them. See  for more info on what it means for a badge to be retired.       Visit the  of the  on any site to see a complete list of badges that you can filter by earned, unearned, or type.


I am currently stuck on this program where the objective is to take input of the size of the array and then to each row of the array with string input of colors.Each row can fit in as many colors. By using another method to check If the row consists of atleast 50% or more of the color blue it will return a "Pass" value or else a "Failure" value. Example input:  2 blue red green blue blue orange red  Example Output:  Failed Pass  My problem is in the check method at line 39 of my code I end up getting a NullPointerException with this line if(x[i].contains(blue))        Is there a efficient way to count how many times "blue" appears and adding it to a counter?  Here is the code: ```  public class BigBlue {     public static void main(String[] args) {         Scanner input = new Scanner(System.in);         int x = input.nextInt();         String[] list = new String[x];         String inputs = input.next();         for(int i = 0;i < list.length;i++) {             for(int j = i; j < i; j++) {             if(inputs == "blue") {                 list[i] = inputs;             }             else if(inputs == "orange") {                 list[i] = inputs;             }             else if(inputs =="red") {                 list[i] = inputs;             }             else if(inputs == "green") {                 list[i] = inputs;             }             else {                 System.out.println("Invalid input");             }             }         }         System.out.println(check(list));      }      public static String[] check(String[] x) {         String[] j = new String[x.length];          for(int i = 0; i < x.length;i++) {             int wordCount = 0;             int counter = 0;             if(x[i].contains("blue")) {                  counter++;             }             String trim = x[i].trim();             wordCount = trim.split("\\s+").length;             int k = wordCount / 2;             if(counter >= k) {                 j[i] = "Passed";             }             else {                 j[i] = "Failed";            }         }         return j;     }  }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


So I am looking to dual boot. I currently have ubuntu installed on my SSD. I bought a new SSD that I would like to install windows 10 on for gaming. How do I go about installing windows without messing up my ubuntu installation?

I got some new hard discs and would like to set my PC up in the following way:   Ubuntu is currently installed on one drive I want to put Windows on a second drive I would like a third drive for shared content (music and stuff) that both OSes can access     What I need to know is what format should the content drive be?  How should I configure the drive order in my bios for GRUB to be boot manager and how to configure GRUB for multi-HDD booting?


I am going on 6th Aug to Gainesville, FLorida, USA. My flight itinerary is as follows: Mumbai to Heathrow - Jet Airways, Heathrow to Miami - American and Miami to Gainesville - American. Transit time at Heathrow is 3 hours. I will be arriving at Terminal 4 and will be departing at Terminal 3. Since Jet and American have a codeshare I guess my baggage will continue checked in and i dont think I have to recheck it. I have a valid F1 visa. Do I need a transit visa? PLs help.

I am traveling from the US to India via London Heathrow on November 6. I will be at LHR on 7th at 6:20 am and departing at 9:25 pm. I'm an Indian national and have a valid US visa.  Do I need a transit visa to stay airside?  I have been scared that British Airways have stopped a few people from boarding flights (no details just rumors).  Do I need a transit visa to stay landside? I want to do some sightseeing. What are the chances of getting past officials using transit without visa concession?  Real stories will help a lot to calm the butterflies in my stomach.


Given a unsigned int x, I want to set the nth bit to y, and y can be either 0 or 1. Is it possible to create an expression using bitwise operators to do this while avoiding the use of any conditional statements? Thanks.

How do you set, clear, and toggle a bit?


This was part of a weird dream I had but I've a vague recollection that it's based on a book that I read a long time ago, in my youth; a character had one of those change-makers that bus conductors used to wear with 'pods' of some description in each column. They then click for change that dispenses the pod into their hands which they then cast.  My feeling is that the story was similar to the Spellsinger series, where somebody from our world crosses over to a magical realm and I probably would have read about the same period, mid to late eighties.

I read this book in high school, and I can't remember what it's called. Some kid learns he has magical ability, but only finds out later that he controls it through some kind of coin changer he's been tinkering with the whole book.


On the HTTPS version of Stack Exchange, all links are HTTPS, except some links on the topbar. I am mainly concerned about links in the inbox.

In preparation for the eventual deployment of full HTTPS support on Stack Exchange, and also to make the currently available "alpha" HTTPS support more usable, all links from Stack Exchange sites to other Stack Exchange sites should be .  Currently, at least the following places still feature links with explicit http: protocol prefixes:   the page footer, the "Hot Network Questions" and "Community Bulletin" modules in the sidebar,  (the site switcher menu is OK, though),   and, of course,   lots and lots of user-supplied links in post and comment content.   I've posted this feature request with the intent to provide a single central place for tracking these issues, rather than having them scattered across multiple meta threads.  If you find more places on SE where protocol-relative links should be used, please report them below.  I fully expect this request, in its full sense, to be treated as  for the time being; however, these issues do need to be fixed at some point before our HTTPS support is ready for "prime time".  Ps. Yes, the next release of  (v1.10) is going to include a general client-side fix for most of these issues.  In the mean time, the  plugin effectively provides the same functionality, and much more besides.


Hi all, having trouble seeing a good render (cycles) of this donut I'm trying to make. Setting is glossy, but seems dark and non-reflective, just looks like puddy and basically all other BDSF looks basically the same. Is not glossy/ reflective!   specs: windows 8.1 intel core i5-4210U  GeForce 840m   Thanks

When I apply a glossy shader to the material of my text, the text becomes just black. Why?    I have lamp and everything, but the problem persists. The text is red before I add the glossy shader.  I'm using Cycles render.   Thanks!


In one of the proofs in class there was given the equality for the dot product:  $$\langle Ax, Ax\rangle = \langle x, A^tAx\rangle$$  I don't understand why this is correct. Is there a way to show this without explicitly looking at the multiplications and sums?  thanks.

I'm trying to prove that for a certain matrix $A$, and its conjugate transpose $A^*$, we have $⟨Ax,y⟩=⟨x,A^*y⟩$, where $⟨⟩$ represent the inner product. So here it's simply the dot product in $R^n$.  Does anyone have an idea of how to prove this?  Thank you!


I'm unable to change username in windows 7 home premium. Even if i change it in control panel, the old name appears in command prompt and also in c:\users. Is there any solution for this?I tried lusrmgr.msc, it is showing,     This computer is running Windows 7 Home Premium. This snapin may not be used with this version of Windows. To manage user accounts for this computer, use the user Accounts tool in the Control Panel.

I have an install of Windows 7 that I've already put a few days into. Today I realized I've made a mistake in the username and it's driving me nuts (my personal OCD).  While changing the physical folder name is perhaps possible, though quite involved, I do not want to open that can of worms.  What I want to do is simply change the username I give when the login prompt shows up. I thought it's possible by just renaming the user account in the User Accounts but that didn't work.  Is it possible to do then? Or is the only way to create another user and spend hour migrating everything I'd already customized to that user?


When you go over the text below with mouse it appears. I saw this in a question somewhere and am wondering where on meta-so or so it is documented.        This is very cool but where is it documented?

As described on , it's now possible to create spoiler blocks/hidden text with the syntax   >! Spoiler text   Can a blurb about this be added to the "formatting help" page that's linked to in the "How to format" box on the right of posting pages and by the little ? block above post entry fields?


I totally understand the problems associated with floating points, but I have seen a very interesting behavior that I can't explain.      float x = 1028.25478; long int y = 102825478; float z = y/(float)100000.0; printf("x = %f ", x); printf("z = %f",z);   The output is:     x = 1028.254761 z = 1028.254780   Now if floating numbers failed to represent that specific random value (1028.25478) when I assigned that to variable x. Why isn't it the same in case of variable z?   P.S. I'm using pellesC IDE to test the code (C11 compiler).

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I want to move that button from bottom to top in launcher as was in unity. How can I do so?

Ubuntu 17.10 introduces the GNOME Shell with the  (based on  GNOME Shell extension) and it allows you to put the Dock on the bottom of the desktop:    However, there is no easy way to move the Show Applications icon (shown on the right) to the left of the Dock. There is no such setting in GNOME Control Center. There is already a  filed, but does anybody know any workaround until it gets fixed by Ubuntu Dock developers?


Would it be possible to create some sort of question difficulty flag which would be enabled for peers with enough rep within that respective tag?  The purposed of this would be to identify questions that people at lower personal experience level would be able to answer.  As peers cast their difficulty rating this would cause the difficulty rating to get averaged and re-calculated.  If this is a duplicate, please guide me to the meta question that already justifies/denies this idea because I was unable to find any.

It might be useful to add a drop down field "Difficulty" for questions. With a very limited set of options, say:   Beginner Advanced Expert   This way, users could easily judge if they can answer a specific question (depending on their experience in the topic) and how much time it will probably take.  Beginners usually know they are new so they can easily select Beginner. Those with some experience just select Advanced and those working on a topic for years may chose Expert. I think it's not very difficult to judge halfway correctly.  And the difficulty rating does not have to be very precise anyway, it's more a rough estimate by the asking person.  As an addition, rep gained on this topic can be multiplied with a difficulty factor. This would solve the problem of lots of rep for often-viewed and easy to answer questions and few rep for less-viewed, difficult questions.  Update  Thank you so far for the answers. I clearly underestimated the fact that some users are going to always chose Expert difficulty.  Maybe readers voting on the difficulty would be a workaround. Of course, we cannot use the rep factor then, for the same reason.  This kind of voting would obviously introduce a whole new set of issues, since we could vote on both content and difficulty (I'm almost positive this kind of proposal existed before?).


In general I standardize my features before regression by subtracting the mean and dividing by unit variance: $$ \hat{X} = \frac{X - \bar{X}}{Var(X)}$$ With this basic standardization, interpreting the regression coefficients is quite straight-forward. Now I've got some not-really-normal-dist data, for which a power transform is a good choice. Since some features contain negative values, I chose to use a Yeo-Johnson transformation. (I could also transform the features containing neg. values to all-positive features if Box-Cox helps the cause...) After this transform, the data is standardized additionally, again by stubtracting the mean and dividing by variance. Question: Is there an easy way to interprete the regression coefficients after a power transform (may it be Yeo-Johnson or Box-Cox...)? A similar question is asked  and the  helps with the fact that feature scaling changes the coefficient interpretation in general, but it is specific to a transformation with the 4th root.  beyond the question After the power transformation, I apply polynomial transformation of degree 2 or 3 with interaction terms and then perform a feature extraction with a PCA to reduce the dimensionality of the problem. Finally the design matrix is passed to a regression algorithm. I guess this further reduces the intepretability for both only standardizing and/or power transform? Any other way to interprete the coefficients by using words? (A graphical interpretation using ICE-plots and the like is imho still fairly easy.)

I'm using fourth root (1/4) power transformation on my response variable, as a result of heteroscedasticity. But now I'm not sure how to interpret my regression coefficients.   I assume that I would need to take the coefficients to the fourth power when I back-transform (see below regression output). All of the variables are in units of dollar in millions, but I would like to know the change in dollar in billions.    While holding the other independent variable constant, a billion dollar change in fees, on average, leads to a change of 32 (or 32,000 dollars) in collections. I take 0.000075223 * 1000 (to get to billions) ^ 4 = 0.000032. Now do I multiply this number by 1 million or 1 billion (the original unit of the dependent variable is in millions)?  lm(formula = (Collections^(1/4)) ~ Fees + DIR)                   Estimate      Std. Error  t value            Pr(>|t|) (Intercept)   2.094573355     0.112292375   18.653  0.0000000000000151 Fees        **0.000075223   **0.000008411    8.943  0.0000000131878713 DIR           0.000022279     0.000004107    5.425  0.0000221138881913


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

To make literature search simpler and more efficient, I'm looking for a good tool that would come up with a list of publications based on a given set of publications/research areas. So far, I've found  but it does not seem to work all that well. I was wondering if someone in this community might know about a better tool or an altogether better approach for pursuing efficient literature search.


What is the exact difference in the meaning between "I got him to catch a taxi" and "I had him catch a taxi" ?  Could I use "I got him catch a taxi" instead of "I got him to catch a taxi" ? if so, What is the exact difference in the meaning between "I got him catch a taxi" and "I got him to catch a taxi" ?  (((( i have thought that "I got him catch a taxi" means "I ordered him and he catched a taxi" and that "I got him to catch a taxi" means "I ordered him and he would catch a taxi" and that "I had him catch a taxi" means " I ordered him and he catched a taxi" and that "I had him catching a taxi" mean "I ordered him and he was catching a taxi".  I have Always confused about the time sequence about those. i have confused whether or not the person who was ordered really did it.  for examples, i want to ask about my confusing.  A---> John let me drive his new car.  a) I drove his new car.   b) I did not decide whether or not I drove his new car.  B----> She made her children do their homework.  a)  Her children did their homework. b)  Her children did not decide whether or not they did their homework.  C=====> I had the mechanic check the brakes.  a) The mechanic checked the brakes. b) The mechanic did not decide whether or not he checked the brakes.  D=====> Susie got her son to take the medicine  a) Her son took the medicine. b) Her son did not decided whether or not he took the medicine.  E=====> Susie got her son take the medicine  a) Her son took the medicine. b) Her son did not decided whether or not he took the medicine.  ))))))  Could I use "I had him to catch a taxi" as "I got him to catch a taxi" ?

I have my hair cut.   I get my hair cut.      What is the difference between the two sentences in meaning?


I'm trying to find the limit of the following function, as $x\to 0$: $$f(x)=\frac{\sqrt{2+x^2}-\sqrt{2-x^2}}{x^2}$$ I'm not at all sure how to solve this. Can anyone give me some pointers?

This problem is from Calculus: A complete course 8 ed.(Adams/Essex). Problem no. 35 chapt 1.2.     Evaluate the limit or explain why it does not exist.      $\displaystyle\lim_{x\to 0}\frac{\sqrt{2+x^2}-\sqrt{2+x^2}}{x^2}$   So I multiplied the fraction with the conjugate of the numerator and ended up with this. I see that $x^2$ can be divided from both numerator and denominator. But after that I am not sure how I should continue.  $\displaystyle\lim_{x\to 0}\frac {2x^2}{x^2(\sqrt{2+x^2} + \sqrt{2-x^2})}$  The answer states that next step is   $\displaystyle\frac {2}{\sqrt{2} + \sqrt{2}}$  But I do not see how it got there. I tried looking up square root laws and how simplify but could not see anything that was useful for me.


My processor is Intel® Pentium(R) CPU N3710 @ 1.60GHz × 4 with 4GB RAM. I tried ubuntu 20.04 but its not running. which version support this spec. which one is better for low specs laptops ubuntu, fedora or mint. I need persistence storage. I tried tail os but its tor browsing is slow, is there any way for normal internet connection in tail os

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


Prove that if $g^2=e$ for all $g$ in $G$ then $G$ is Abelian.   This question is from group theory in Abstract Algebra and no matter how many times my lecturer teaches it for some reason I can't seem to crack it.   (Please note that $e$ in the question is the group's identity.)  Here's my attempt though...  First I understand Abelian means that if $g_1$ and $g_2$ are elements of a group $G$ then they are Abelian if $g_1g_2=g_2g_1$...  So, I begin by trying to play around with the elements of the group based on their definition...  $$(g_2g_1)^r=e$$  $$(g_2g_1g_2g_2^{-1})^r=e$$ $$(g_2g_1g_2g_2^{-1}g_2g_1g_2g_2^{-1}...g_2g_1g_2g_2^{-1})=e$$  I assume that the $g_2^{-1}$'s and the $g_2$'s cancel out so that we end up with something like,  $$g_2(g_1g_2)^rg_2^{-1}=e$$ $$g_2^{-1}g_2(g_1g_2)^r=g_2^{-1}g_2$$  Then ultimately...  $$g_1g_2=e$$  I figure this is the answer. But I'm not totally sure. I always feel like I do too much in the pursuit of an answer when there's a simpler way.  Reference: Fraleigh p. 49 Question 4.38 in A First Course in Abstract Algebra.


Is it possible to hook up a MySQL database with python program if the MySQL database is made in PhpMyAdmin?

How do I connect to a MySQL database using a python program?


Let $B$ be a matrix of size $n \times n$  (1) $B$ is called nilpotent if $\exists k \in\mathbb{N}$ so that $B_k$ is the zero matrix. Prove that if the matrix $B$ is nilpotent, then the determinant of $B = 0$.   (2) $B$ is called skew-symmetric if its transpose is equal to $−B$. Lets assume that $B$ is skew-symmetric and invertible. Show that $n$ is even.  From my understanding, a nilpotent is a matrix $N$ such that the eigenvalues of the matrix are all zero. I was thinking that I need to link this definition to be able to prove that the determinant of the matrix is zero. Furthermore, in part (2), I am completely confused where to begin. I am not sure how to prove that $n$ is even.   Any help would be much appreciated, thanks in advance.

Let $B_{nxn}$ be a nilpotent matrix. How should I go around proving that $B$ is not invertible? I was thinking this: if $B*B = 0$ , then if I rank $B$ to echelon form, I will always have two or more rows that are the same, and then because $B$ is square, it is not possible to find another matrix ($B^{-1}$)that will transform $B$ to $I_{n}$... But I don't know how to write it mathematically


Say I am interested in predicting the TOTAL number of people that survive the titanic disaster, NOT each individual who died. Is it possible to run a probabilistic classifier on the data getting a value for each individual between 0 and 1, then summing those values for a best guess?

Say I have the titanic kaggle competition, but I'm not interested in the competition for predicting survival for each individual. Instead I want the most accurate estimate of total survivors on the titanic. Would this be achieved by using a probabilistic model, then adding the probabilities for each individual? For example, if I have 3 people and 1 survived, but my model produced 0.4, 0.4, and 0.4 probabilities for each person to survive, I calculate 0 survived. But if I add 0.4 for each person, I get 1.2, which is closer to the actual. Does this make sense?


Is it possible to have some sort of regex that matches regex?  For example, the regex would match /(.*?)/ but not /(.?+/.  I am not really looking for an example (since I would have absolutely no idea how it works nor do I really need one) but I would like to see what you come up with as a working example.  Thanks in advance!

Is it possible to detect a valid regular expression with another regular expression?  If so please give example code below.


I think the answer is 3. The convex sets are intervals, of course, and may be of any type; any two intervals that look alike are homeomorphic. So we add $(a,b)$ and $[a,b]$ to our count. Since intervals like $(c,d]$ are not homeomorphic to either of the previous two intervals, it is a third type. Finally, $(c,d]$ is homeomorphic to $[a,b)$, so we do not add $[a,b)$.  Am I correct?

I want to describe, up to homeomorphism, all the proper connected subsets of $\mathbb{R}$. I know the theorem that $A \subset \mathbb{R}$ is connected if and only if $A$ is an interval.  So consider the following intervals:  $[a,b), [a,b], (a,b)$  Note $[a,b)$ is not homeomorphic to $[a,b]$ (compactness argument) and $[a,b)$ is not homeomorphic to $(a,b)$ (by connectedness). Similary $[a,b]$ is not homeomorphic to $[a,b)$ (remove a,b from [a,b]).  Now any ray $(a,\infty)$ is homeomorphic to $(1,\infty)$ which is homeomorphic to $(0,1)$ and $(0,1)$ is homeomorphic to $(a,b)$. Similarly the ray $[-a,\infty)$ is homeomorphic to $(0,1]$. So I think this covers all the cases.   So I believe the answer is $3$, yes?


I am starting in my studies on topology and I am having really big troubles with this kind of stuff  I have $(\mathbb R, \tau_u)$, and I have to prove that $A \in \tau_u$ iff $A=\uplus_{i\in I}]a_i, b_i[$  If someone could help me with well-structured demostration of this, I would really appreciate it.

Let $U$ be an open set in $\mathbb R$. Then $U$ is a countable union of disjoint intervals.    This question has probably been asked. However, I am not interested in just getting the answer to it. Rather, I am interested in collecting as many different proofs of it which are as diverse as possible. A professor told me that there are many. So, I invite everyone who has seen proofs of this fact to share them with the community. I think it is a result worth knowing how to prove in many different ways and having a post that combines as many of them as possible will, no doubt, be quite useful. After two days, I will place a bounty on this question to attract as many people as possible. Of course, any comments, corrections, suggestions, links to papers/notes etc. are more than welcome.


We use Google's cloud compute engine for some of our servers. I'm hoping someone will have some experience of scheduling tasks with gcloud!  I have written a windows batch script that creates snapshots of these servers. This is using the cloud SDK for Windows. When I double-click the script to run it interactively myself it works fine. Here are the contents of snapshots.bat:  cd "C:\Program Files (x86)\Google\Cloud SDK" set snapshotdate=%date:~-4,4%%date:~-7,2%%date:~-10,2% gcloud compute disks snapshot [sanitised]   When I try to run it via a scheduled task in Windows, nothing happens. Checking the task logs reveals this:  Task Scheduler started "{681b1f5f-265b-499d-bd36-7b1d5bfcc833}" instance of the "\Run daily snapshots gcloud compute" task for user "AD\ewan.mclean".  Task Scheduler launched action "C:\Windows\SYSTEM32\cmd.exe" in instance "{681b1f5f-265b-499d-bd36-7b1d5bfcc833}" of task "\Run daily snapshots gcloud compute".  Task Scheduler successfully completed task "\Run daily snapshots gcloud compute" , instance "{681b1f5f-265b-499d-bd36-7b1d5bfcc833}" , action "C:\Windows\SYSTEM32\cmd.exe" with return code 2147942401.  Task Scheduler successfully finished "{681b1f5f-265b-499d-bd36-7b1d5bfcc833}" instance of the "\Run daily snapshots gcloud compute" task for user "AD\ewan.mclean".   I've looked up the return code but it's very vague. I presume it has something to do with the way the initialisation of the cloud environment works with the user's profile etc. I have however set it to run as me with my password as a test:      Anyone have any suggestions, or a better way to do this?

I'm trying to run a batch file on Windows 7 from the Task Scheduler.  I can run the batch file fine if I run it from the command prompt.   If I run it from the Task Scheduler to only run when the user is logged in, the task will run without any issues. However, when it runs when the user is not logged in, the Task Scheduler looks like it's running the file but nothing happens.    I've tried changing the batch file to nothing but the following line to ensure it's not because of what's in the batch file:  echo "success" >> c:\temp\test.log   and that does not work.  Any ideas?  I have it being run with the highest privileges and with an admin account that has full permissions to the batch file and the folder where the file is being written.


When I go to a subreddit on Reddit, I see immediately in the sidebar what its scope is. When I go to stackexchange.com and click "Feedback always welcome", I get this place where I can ask questions.  Bug reports and feature proposals are not questions, and users should get reinforced that they are in the right place here.  The purpose of meta.stackexchange is explained on the help pages, but they are hard to reach: there is a miniature  button on the bottom of each page. Clicking help in the top bar shows Tour (which seems useless), Help Center (which discourages me further), and What's Meta?, a link to an essay about the purpose of meta.  Guys (m/f), it can be really easy to show purpose in simple language. For inspiration, check out , , , , , .  What do you think?

A guest at my house over the weekend stood puzzled next to my driveway. "What is that for?" she asked, pointing to a framework of 2x4s and hardware cloth perched on an old tire amid piles of sand. "Sifter." I said. "For what?" "For sifting gravel." "Why?" "To line walking paths, such as the one you're standing on..." Spend enough time working with something, and it's easy to forget how strange and unnatural your makeshift tooling can appear to those unfamiliar with it.  Such is the nature of these meta sites. For 5 years, we've been directing folks to them for discussion and feedback, to commune with their community, hash out misunderstandings, propose changes and document the current state of things. And... We haven't always been good about helping them get past the initial shock and confusion of dealing with this system. This has manifested in several unfortunate behaviors:  Downvoting of legitimate support questions - those that are not duplicates and reflect an actual bug or honest misunderstanding of how the system operates. Folks who are acting in good faith should be treated as such - , not shutting them down.  Closing questions that seek input and discussion from the community - in hindsight, adding "primarily opinion based" as a close reason on meta sites was... a terrible idea. The old "not constructive" close reason made some sense for rants and so on, but for a discussion site closing down questions that solicit opinions is just silly. Here on MSE, we prefer the following off-topic reason instead:  This question does not appear to seek input and discussion from the community. If you have encountered a problem on one of our sites, please describe it in detail. See also:    The perception that Stack Exchange is disrupting the normal operation of the site by talking about future plans - even when those plans involve the community. I talked about this a bit more on , but seeing this kind of backlash toward folks at the company who were trying to be open and receptive to discussion about what they were doing was kinda disheartening - we need to be doing more of that, not less.  A reluctance to ask questions about asking questions - which is about as meta as you can get, and yet we probably get more of these via email than we see on meta, while being the least-qualified to answer them well.   After an increasing number of complaints from both core users and moderators on a number of sites, we're taking a hard look at how we can improve this situation... Starting with a change to :  Meta is for...  ...$SiteName users to communicate with each other about $SiteName (asking questions about how the websites work, or about policies and community decisions) ...$SiteName  users to communicate with Stack Exchange the company (posting bugs, suggesting improvements, or proposing new features), and ...Stack Exchange to communicate with the community (soliciting feedback on new ideas or features, or discussing policies that affect the whole network)  Lots of topics are fair game, as long as they are about the Stack Exchange family of Q&A sites in some way. Any issue that concerns the core Stack Exchange engine that runs all Stack Exchange websites is welcome here.  This replaces the previous bullet list of specific topics, and aims to outline broad purposes with examples for clarification rather than constraining the scope to those examples. So... that's a start. But a documentation change isn't going to change misconceptions that've already built up among newer users. So I'm asking y'all for help: What do you think meta should be used for, and how can we better communicate this intent to new users?


Problem: prove $\sqrt{2\sqrt{3\sqrt{\cdots\sqrt{n}}}}<3$ by induction. I tried some, but stopped in $\sqrt[2^n]{n+1}$. Also tried with $2\sqrt{3\cdots}<3^2$ and so on.

I know that: $\sqrt{1+2\sqrt{1+3\sqrt{1+4\sqrt{1+\cdots}}}}=3,$ which is one of Ramanujan's infinite radicals. So surely the expression in question is less than $3.$ But how can I prove this without mentioning this or in general how to prove: $\sqrt{2\sqrt{3\sqrt{4\sqrt{\cdots\infty}}}}<3$ ? I'm not quite sure, how to approach this? Expressing the expression as an infinite product: $$\prod_{i=1}^{n} i^{\frac1{2^{i-1}}},\text{ as }n\to\infty$$ and then using some sort underlying inequalities might help! Please suggest. Thanks in advance.


Let $f:[a,b]\to\mathbb{R}$ be Riemann-integrable and $F(x)=\int_a^xf(t)dt$. Is this function $F$ always differentiable? Because the antiderivative is defined as $F'=f$ right, so you would think that it always holds.

I would like to know if there exists an indefinite integral which is not differentiable? Is this possible? That is, I want to know if there exists a real function F defined in a interval $[a,b]$ by the equation $$F(x)=F(a)+\int_a^x f(t) dt $$ where $f:[a,b]\rightarrow \mathbb{R}$ is only Riemman integrable, that F is not diffentiable of such a function? Could you give an example? Thank in advance!


I´ve been assigned finding the non-trivial ($x+y\neq0$) solutions to this equation, if they exist. We have recently studied $\mathbb{Z}[\omega]$, where $\omega$ is a third root of unity. I tried factoring the equation into $$(x+y)(x+\omega y)(x+\omega^2y)=3z^3.$$ As I can suppose that $(x,y)=1$ because the equation is homogeneous, I could deduce that $x+y,x+\omega y$ and $x+\omega^2y$ have no common factors except maybe for the prime $1-\omega$, with exponent $\leq1$. We also know that $x+y$ is multiple of 3 (so, of $(1-\omega)^2$) looking at the equation mod 3 in the integers. And I could see too, using that $x\equiv1,y\equiv-1$ módulo 3, that $x+\omega y,x+\omega^2y$ are multiples of $\lambda$ but not of 3. So, as $(x+y)(x+\omega y)(x+\omega^2y)$ is 3 times a cube, I could express for some natural $n$ and $a,b\in\mathbb{Z}[\omega]$, with $a$ integer, and $u$ unit in $\mathbb{Z}[\omega]$: $$x+y=3^na^3\text{ (using that $x+y$ is an integer)}$$ $$x+\omega y=u(1-\omega)^mb^3$$ $$x+\omega^2y=\overline{u}(1-\omega^2)^m\overline{b}^3.$$ However I don´t know how to continue from here or if this is the right path. I searched a bit but didn´t find papers in English that explained a solution to this equation. Any help is appreciated :).

I haven't found any useful method to solve the following problem: Prove that if $x,y,z\in\mathbb{Z}$ and $x^3+y^3=3z^3$ then $xyz=0$.  Source:


Interesting situation came up in my session. The players captured a wizard NPC and put him in jail. Then came a long discussion about what measures needed to be taken in order to prevent said wizard from using spells to force his way out.  Basic measures like removing a spell book, holy/arcane focus, and spell components would prevent use of any spells with a material component. A gag would stop verbal spells and being bound would stop somatic spells. However this is an unsustainable level of treatment for a jail for more than a day or so since it would have to be applied to ALL prisoners since there is no easy way to tell who can cast and who can't.  Preventing a long rest would severely handicap most casters in that it would prevent recovery of spell slots/sorcery points, although a warlock wouldn't be affected. Seems like a basic precaution to not allow prisoners long periods of rest. But this doesn't affect unused spell slots and no character class, from what I can tell, "loses" spells if they don't perform some sort of ritual each day (they just can't change their prepared spells if applicable), even the wizard. So unless a caster is tapped out on spell slots/sorcery points before being jailed, they would always retain what they have left even if denied a long rest (and would still have cantrips).  So, apart from being tightly bound, gagged, and stripped, are there any ways to prevent casting that I'm missing?  There are plenty of verbal only spells that would be useful in a jail environment (Command, Knock, Misty Step) so really, how are casters supposed to be locked up other than some sort of dedicated magicked prison (assuming you could even transport them there)? Just taking out the gag to feed them opens up the possibility of a spell being cast. I don't want my characters to have to be treated like this if they get jailed, but it seems like in a world of scarse magic items but numerous magic wielding people, anyone not KNOWN to be non-magic using would be treated like Hannibal Lecter or put in an Arkham Asylum type specialty prison (bad example, folks escape from there all the time! Maybe the one from Harry Potter).  My homebrew solution is to have the higher levels of exhaustion stop casting. This way someone who has been in a jail for more than a few days can't cast due to poor conditions, poor food, etc. But they can still move around a bit and talk, so there are role playing possibilities (barter for more food, become prison kingpin to get better treatment, bribe a guard, etc). When captured maybe casters could be bound and gagged, but it wouldn't be necessary for long term imprisonment.  I'm using the basic vanilla forgotten realms setting with the suggested "low magic item availability" from the 5e PHB and DMG. Judging from the published campaigns I've read (Phandelin and Horde) there does not seem to be common availability of magical effects and devices. Party level is 5-9th level.  The answers to the previous setting-free question  has plenty of useful "soft" suggestions like archers on the roof. But I would like some 5e and Forgotten Realms-specific techniques.

The modern concept of crime and punishment is very reliant on the ability to disarm and restrain and control an individual (think handcuffs, the dividers in police cars, and jails).  How can that be replicated in a world where even a wizard's apprentice has a much power as an armed man with a handgun?  I've seen stories where magical restraints are present, but you can't write that into every thorp and hamlet, even in Eberron.    How can you restrain a magic user in a fantasy setting?   Either answers that conform to modern concepts of crime and punishment or answers about restraining a magic-user in a psuedo-medieval setting are acceptable.


When I start up windows normally it just freezes , I click "Launch Startup Repair" I get this:   "Windows has encountered a problem communicating with a device connected to your computer.  This error can be caused by unplugging a removable storage device such as an external USB drive while the device is in use, or by faulty hardware such as a hard drive or CD-ROM drive that is failing. Make sure any removable is properly connected and then restart your computer  If you continue to receive this error message, contact the hardware manufacturer"   How do I fix this problem?

I am having this error for quite a few months. When the problem occurs, my windows freezes at boot time with black screen. After few reset attempts, sometimes it shows the entitled error. after few attempts, the windows starts but everything become slow. If I again restart, it works well. But at a point windows never starts and I have to reinstall it. I have already reinstalled 3/4 times in the past 2/3 months. I checked for any HDD errors with EASEUS Partition Master Home Edition with surface test, chkdisk at boot time etc for my C drive and F drive but no errors found. Startup repair also fails to solve the problem.  Windows Boot Manager   Windows failed to start. A recent hardware or software change might be the cause.   To fix the problem:    1. Insert your Windows installation disc and restart your computer.    2. Choose your language settings, and then click "Next."   3. Click "repair your computer."  If you don't have this disc, contact your system administrator or computer manufacturer for assistance.     File: \Boot\BCD    Status: 0xc00000e9  My laptop's info:  Model: Dell n5110 corei5 OS: Windows 8 PRO 64 bit Anti-virus:  Avast Home edition  Additional info: My Program Files, Program Files (x86) and Users directory is located at F drive and linked with symbolic link (mklink). Also I have changed these basic locations from regedit. I also use eclipse android intelx86 emulator, virtualbox and Genymotion emulator most often.


I am looking for a Latex command to print the mathematical contradiction symbol, which is the upside-down T.

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


Assume that $a_n >0$, $n\in\mathbb{N}$, and that $\sum\limits_{n=1}^\infty a_n $ converges. Show that for $\alpha>1/2$ the series $$\sum\limits_{n=1}^\infty \frac{\sqrt a_n}{n^\alpha}$$ converges as well  I think we can use Abel's convergence test but I'm not sure if that is the way to go

Suppose $\sum{a_n}$ converges. How do I prove that $\sum{\frac{\sqrt{a_n}}{n}}$ converges.  So I know that just because  $\sum{a_n}$ converges, do not mean I can say anything about the converges of its square root. So I know that I can prove that if  $\sum{\sqrt{a_n}}$ converges then $\sum{\frac{\sqrt{a_n}}{n}}$ converges by Abel's Test, but I do not know where to start for the case where  $\sum{\frac{\sqrt{a_n}}{n}}$ diverges


Pardon my total lack of knowledge in complex geometry.  How would one go about proving that the connect sum of 3 copies of $\mathbb{C}P^2$ does not admit a complex structure?  Note that this manifold does admit an almost complex structure.

I know the chern classes-related theorem that states that $\mathbb{C}\mathbb{P}^2\# \dots \# \mathbb{C}\mathbb{P}^2$ ($k$ times) has no almost complex structure (hence no complex structure) if and only if $k$ is even.  I also know that $\mathbb{C}\mathbb{P}^2\# \mathbb{C}\mathbb{P}^2 \# \mathbb{C}\mathbb{P}^2$ has no complex structure, hence the almost complex ones you define on it are not integrable.  Where can I find a proof of this proposition? How do I see that the connected sum of three (or five, or seven, or every odd number) copies of $\mathbb{C}\mathbb{P}^2$ doesn't admit a complex structure?


Why does the following produce such different results?  >>> sys.getsizeof(int) # same as sys.getsizeof(object), sys.getsizeof(type) 400  >>> sys.getsizeof(1) 28   Is the actual size of the item 1 equal to the size of the object (400) + the size of the actual integer value (28) = 428, or how exactly does the integer/object creation work here?

I want to know how to get size of objects like a string, integer, etc. in Python.  Related question:   I am using an XML file which contains size fields that specify the size of value. I must parse this XML and do my coding. When I want to change the value of a particular field, I will check the size field of that value. Here I want to compare whether the new value that I'm gong to enter is of the same size as in XML. I need to check the size of new value. In case of a string I can say its the length. But in case of int, float, etc. I am confused.


Installing docker and docker-compose on ubuntu needs many steps.    E.g. for Arch you only need pacman -S docker docker-compose   Why is the apt for docker-compose 'outdated'? (Version 1.24 vs. 1.21) How can I help to change this? Why use Docker another repository which I have to add?    My understanding about apt and how to maintain is a little bit poor. And I can't find something like in the the Arch package list, where you can read the package file. ()

Why are packages in the official Ubuntu repositories older than the latest (upstream) versions from Debian Sid, PPAs, the authors, etc.?


Which one is the correct (or more commonly used) form: "3-month retreat" or "3-months retreat"?  How about "3-day" vs. "3-days" and "3-week" vs. "3-weeks" in the same context? (This is retreat as in meditation retreat and for U.S. English.)

Why are year, pound and mile in the singular form in the phrases below?   five-year-old children  20 pound note 10 mile run   Is that because they're acting as adjectives, which are always invariable in English?  Is it incorrect to say...   five-years-old children? 20 pounds note? 10 miles run?


thank you for taking the time to read this. Sorry if my question is dumb, I tried searching but couldn't quite figure out why I'm having this problem. I was trying to test some code for another application, but I'm having issues. Perhaps I just don't understand arrays properly.  I have a method named halfStepUp in a class named Transpose that, for testing purposes, should return "c#" if given "c" and "d#" if given "d". This is the code:  public class Transpose{     public static String halfStepUp(String note){         String n = null;         if (note == "c") n = "c#";         if (note == "d") n = "d"#;         return n;     }    }   I have the following code in my main method:  String [] scale = new String[2]; scale[0] = "c"; scale[1] = "d";  System.out.println(Transpose.halfStepUp(scale[0]));   This prints "null." What am I doing wrong?  I know the method works because if I use  System.out.println(Transpose.halfStepUp("c"));   It works fine. The solution is probably embarrassingly easy but I couldn't find a good way to word it when searching for help. Thanks again for reading, and any answers are greatly appreciated!

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


So there is a question which was aked to me a long while ago (and I don't remember what was the answer) so here goes:  Captain Kirk is on a remote planet again and there is a monster trying to eat him. Fortunately, captain Kirk has a super-shielding device with him. The device casts a perfectly circular 10 meter around it. Captain Kirk uses it to protect himself from the monster. The problem is that while he is inside the protective range of the device, captain Kirk cannot be beamed away. As soon as he leaves the shield, he can (instantly) be beamed away.  What is the highest ratio $\dfrac{\text{speed of the monster}}{\text{speed of Kirk}}$ so that Kirk still has a chance to escape?  So in math terms:   the prey is inside a circle of radius $r$ (the actual value does not matter, so say it's 1). the predator is outside the circle and cannot enter. if the predator is at the point of exit of the prey, then the predator wins. otherwise, the prey wins. The answer should hold independently of the starting positions. (In other words, assume a worst-case scenario for the prey).   The answer is not $\pi$!  A first thought of many (including me) is to say the answer is $\pi$. This turns out to be wrong.  First, one can assume that the prey begins at the center of the circle and the monster on the boundary. This case encompasses the worst-case scenario: if the prey is not in the center, then it can go to the center; if the predator is not on the boundary of the circle, then it's only better for it to be on the boundary.  Next, consider the following strategy. The prey start to run for the point on  the boundary opposite to the predator. The predator will then start to run along the circle either in clockwise or counterclockwise manner. Once the prey is at the middle of this radius, it makes an angle (about 37°) to go a point which is further away form the predator. Note that the angle is too small (so it's not worth for the predator to start to run in the opposite direction). Both the predator and the prey have now a longer way to go, but the predator more so. With the given data, the predator would need a speed of at least 3.3.  Even better  Here is a better strategy. Decompose the motion of the prey as radial and angular. Note that when the prey is closer to the center a small speed is sufficient to get a large angular speed.   Assume for simplicity that the speed of the prey is $1$ and that of the predator $v$. Then the prey can run to some point on the border (and the predator will start to run around the circle). As long as the prey is inside a smaller circle of $\tfrac{1}{v}$ the radius, it may have a higher angular speed than the predator. This means it can use parts of its speed to move radially until it gets as close as possible to this radius all the while haveing the predator on the opposite side of the circle.   After a very long time, being as close as desired to the circle of radius $\tfrac{1}{v}$ the prey can try to dash for the point opposite the predator.  This means that the prey has $1-\tfrac{1}{v}$ time units to the boundary while the predator would need $\tfrac{\pi}{v}$. This shows that as long as $v < \pi +1$ the prey can win.  Now obviously, you can still improve upon that later strategy (for example, by using the former strategy at some point). But in the end, I still don't know what is the actual supremum of the speed ratios.

A famous problem:  A lady is in the center of the circular lake and a monster is on the boundary of the lake. The speed of the monster is $v_m$, and the speed of the swimming lady is $v_l$. The goal of the lady is to come to the ground without meeting the monster, and the goal of the monster is to meet the lady.  Under some conditions on $v_m,v_l$ the lady can always win. What if these conditions are not satisfied?  Edited: the monster cannot swim. If the conditions are not satisfied, then monster can always perform a strategy such that the lady will not escape the lake. On the other hand this strategy is not desirable for both of them because they do not reach their goals. As there was mentioned, this deals with undecidability of the problem. On the other hand, if you imagine yourself to be this lady/monster, you can be interested in the strategy which is not optimal. What is it? If there are such strategies in the game theory?  Edited2: My question is more general in fact. If we have a game with one parameter $v$ when two players $P_1, P_2$ are enemies and if $v>0$ then for any strategy of $P_2$ the player $P_1$ wins. If $v\leq 0$ then for any strategy of $P_2$ there is a strategy of $P_1$ such that $P_2$ does not win and vice versa. I am interested in this case. From the mathematical point of view as I have understood the problem is undecidable since there is no an ultimate strategy neither for $P_1$ nor for $P_2$. But we are solving somehow these problem IRL. Imagine that you are a lady in this game - then you would like to win anyway even while knowing that your strategy can be covered by the strategy of the monster. On the other hand, the monster knows that if he will cover all strategies of the lady she will never reach the shore and he will never catch her. I mean they have to develop some non-optimal strategies. I hope now it's more clear.


I'm attempting create my first dynamodb app on android and get receiving a null-pointer error that I can not figure out why.  I've written the following asyntask:  class CheckIfEmailNull extends AsyncTask<String, Void, Void>{          DynamoDBMapper dynamoDBMapper;           @Override         protected Void doInBackground(String... userID) {              AmazonDynamoDBClient dynamoDBClient = new AmazonDynamoDBClient(AWSMobileClient.getInstance().getCredentialsProvider());             this.dynamoDBMapper = DynamoDBMapper.builder()                     .dynamoDBClient(dynamoDBClient)                     .awsConfiguration(AWSMobileClient.getInstance().getConfiguration())                     .build();              userB = dynamoDBMapper.load(SecureUsersDO.class, userID[0]);             return null;         }     }   With the following method to written to initiate it:  public void checkUserEmail(Profile profileTest){          Log.d("checkUserEmail>>>", profileTest.getId().toString());          CheckIfEmailNull checkIfEmailNull = new CheckIfEmailNull();         checkIfEmailNull.execute(profileTest.getId().toString());          if (userB.getUserId() == profileTest.getCurrentProfile().getId()){             Log.d("ID's match: ", "attempting");             if (userB.getEmail() == null){                 Log.d("TODO", "Write code to show we need email");                 Log.d("User B is : ", userB.getFirstName());             }         }     }   Yet i get the following error:  05-19 09:33:37.034 6156-6156/com.ronone.securesender E/AndroidRuntime: FATAL EXCEPTION: main     Process: com.ronone.securesender, PID: 6156     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ronone.securesender/com.ronone.securesender.HomeActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.ronone.securesender.amazonaws.models.nosql.SecureUsersDO.getUserId()' on a null object reference         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)         at android.app.ActivityThread.-wrap11(Unknown Source:0)         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)         at android.os.Handler.dispatchMessage(Handler.java:106)         at android.os.Looper.loop(Looper.java:164)         at android.app.ActivityThread.main(ActivityThread.java:6494)         at java.lang.reflect.Method.invoke(Native Method)         at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.ronone.securesender.amazonaws.models.nosql.SecureUsersDO.getUserId()' on a null object reference         at com.ronone.securesender.HomeActivity.checkUserEmail(HomeActivity.java:180)         at com.ronone.securesender.HomeActivity.onCreate(HomeActivity.java:66)         at android.app.Activity.performCreate(Activity.java:7009)         at android.app.Activity.performCreate(Activity.java:7000)         at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)   Thanks for any help in advance.

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


I have an created a page, that after 5 seconds of inactivity fires a external HTML video loop page via the innerHTML function.  When user resumes activity via mousemove or mousedown I am then replacing the video page using the innerHTML to output back to home page.   The video loop after inactivity and reloading of page work absolutely fine.   Here is a working   This issue I have is with an onclick function no longer working within the dynamically output innerHTML.  I am trying to use the following code     var timeoutID;  function setup() {    this.addEventListener("mousemove", resetTimer, false);    this.addEventListener("mousedown", resetTimer, false);    this.addEventListener("keypress", resetTimer, false);    this.addEventListener("DOMMouseScroll", resetTimer, false);    this.addEventListener("mousewheel", resetTimer, false);    this.addEventListener("touchmove", resetTimer, false);    this.addEventListener("MSPointerMove", resetTimer, false);     startTimer(); }  setup();  function startTimer() {    // wait 5 seconds before calling goInactive    timeoutID = window.setTimeout(goInactive, 5000); }  function resetTimer(e) {    window.clearTimeout(timeoutID);    goActive(); }  function goInactive() {     document.getElementById("content").innerHTML="<object type='text/html' data='http://bubbleweb.eu/sp-interactive/video.html' ></object>";  }  function goActive() {       document.getElementById("content").innerHTML='

&times;
Test the Modal..

'     startTimer(); }  ////////// Smart button working, but not dynamically in innerHTML ////////// function smart_fm_btn() {   var x = document.getElementById("smartfm");   if (x.style.display === "none") {     x.style.display = "block";   } else {     x.style.display = "none";   }    var y = document.getElementById("home");   if (y.style.display === "block") {     y.style.display = "none";   } else {     y.style.display = "block";   }  } body {   font: 100%/1.4 Verdana, Arial, Helvetica, sans-serif;   background: #42413C;   margin: 0;   padding: 0;   color: #000; } .container {   width: 1080px;   height:1960px;   background: #FFF;   margin: 0 auto; /* the auto value on the sides, coupled with the width, centers the layout */ } .content {   padding: 0px 0; }

     to swap the display styles of both the 'home' and 'smartfm' divs on the click of 'smart-fm-btn'. This works fine if I code it in page naturally but fails when outputting dynamically via the innerHTML.  If somebody could please share some input in to what I might be doing wrong here I would be eternally grateful. I have been trying to get this to work for past 2 days! :/

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I guess it is simple but I couldn't figure it out. I want it for asp.net project.   Normally I use Int for sql parameter for one int value but I need it for in() statement.  alter procedure abc   @id int  select * from tbl where id = @id   It works for one value,  alter procedure abc   @id int -- how should I change it  select * from tbl where id in (@id)   that one which I want. And how can I send the values in asp.net c#. Normally I send int value, but I do not know either?

Is there a way to pass the array of values to the IN section of a SP as a single paramter for SQL Server 2005?  Ex:  Select * from MyTable where ID IN(@MyValueArray)


Everyone knows how simple arithmetic in Java works for primitives:  int one = 1,two = 2,three = one + two; double four = (one + two) / three; if(four % 1 == 0){      System.out.println("Yay for simple maths!"); } else{   throw new RealityError("http://www.youtube.com/watch?v=H91rPIq2mN4");  }   But the moment that you leave primitives things become complicated fast! Attempting to repeat the previous simple arithmetic is quite the challenge!  BigInteger bigOne = BigInteger.ONE, bigTwo = BigInteger.valueOf(2),             bigThree = bigOne.add(bigTwo);     BigDecimal bigFour = new BigDecimal(bigThree.divide(bigOne.add(bigTwo)));     if (BigInteger.valueOf(bigFour.longValueExact()).mod(BigInteger.ONE).equals(BigInteger.ZERO)) {         System.out.println("Yay for simple maths?!?!");     } else {         throw new RealityError("http://www.youtube.com/watch?v=H91rPIq2mN4");     }   Why aren't annotations used for operators like +, -, *, or /? Such as @DefaultAddOperator for a class that extends Number. Or, in the BigInteger class, why can't it implement an interface that simply states what operation to do when an operator is called on the class. This notion isn't too far fetched, I mean it's used with "Hello World!".toString() and the overloaded operator +, and would simplify the above class based arithmetic considerably.

Coming from C++ to Java, the obvious unanswered question is why didn't Java include operator overloading?  Isn't Complex a, b, c; a = b + c; much simpler than Complex a, b, c; a = b.add(c);?  Is there a known reason for this, valid arguments for not allowing operator overloading? Is the reason arbitrary, or lost to time?


Why didn't the killing curse by Voldemort backfire in the Forbidden Forest when Voldemort tried to kill Harry in Harry Potter and the Deathly Hallows, while it did backfire at the end and Voldemort died?

And in Deathly Hallows, why didn't the Killing Curse rebound when Voldemort tried killing Harry with the Elder Wand when Harry was undefended?


Write a function called mergeCounters which accepts two objects where all of the values are numbers and returns a new object with the total of both objects. The order of your returned object does not matter, as long as it contains the correct keys and values!   function mergeCounters (object1, object2) {   var myObj = {};   for (key in obj1) {     for (key2 in obj2) {       var val = myObj[key + key2];     }   }   return myObj; }  var obj1 = {a: 1, b:2, c:3}; var obj2 = {a: 3, b:6, c:7}; console.log(mergeCounters(obj1, obj2)); // {a:4, b:8, c:10}  var obj3 = {a: 1, c:3, d:5}; var obj4 = {a: 3, b:6, c:7, z:20}; console.log(mergeCounters(obj3, obj4)); // {a:4, b:6, c:10, d:5, z:20}

I need to be able to merge two (very simple) JavaScript objects at runtime.  For example I'd like to:  var obj1 = { food: 'pizza', car: 'ford' } var obj2 = { animal: 'dog' }  obj1.merge(obj2);  //obj1 now has three properties: food, car, and animal   Does anyone have a script for this or know of a built in way to do this?  I do not need recursion, and I do not need to merge functions, just methods on flat objects.


I have read all the answer about importing dxf to QGIS, but I still not understand yet.  Does anyone have a video link (youtube or another) that show me step by step to export dxf with Z point to QGIS?

I have a dxf file of 3d contours. after import it does have only  layer,x,y attribute and doesn't have Z attribute.  How can I provide Z attribute to create a TIN file?


I need some help with this code, when i try to show all chars in Java with the "for loop" it's okay, java shows me all, when i do this with the "for each" i have only undefined  symbols  char[] chars = new char[65535];     for (int go = 0; go < chars.length; go++) { // THIS CODE IS OKAY!         // for (int go : chars) { // **THIS CODE DOESN'T WORKS! WHY??**          chars[go] = (char) go; // Change int type to char     }     for (char owo : chars) { // Output characters         System.out.println(owo);     }

Consider:  List<String> someList = new ArrayList<String>(); // add "monkey", "donkey", "skeleton key" to someList     for (String item : someList) {     System.out.println(item); }   What would the equivalent for loop look like without using the for each syntax?


Why $I$ is a proper ideal implies $1\notin I$?  The definition of proper ideal only requires $I\neq R$. I don't get it.

I have to prove that if $I\subseteq R$ is an ideal, and $1\in I$, then $I=R\,$. So I know $I\subseteq R$ is an ideal if $a,b\in I$ implies $a+b\in I$, and if $a\in I$, $r\in R$, then $ra\in I$. I'm finding it hard to put this into words. Since $1\in I$ and $I\subseteq R$ is an ideal, then let $a=1$ and $r=1$ so $1\cdot 1\in R\,?$


I want to make replace a string in a file mytest.properties but it is not getting replaced.  I want to replace JaWov5Svh/GKAkk8siezbg== and use the command  $ sed -i -- 's/JaWov5Svh/GKAkk8siezbg==/abjhdgetsjsu/d' mytest.properties   but the string does not get replaced as expected.

I am looking for a way to replace a string in a file with a string that contains a slash by using sed.  connect="192.168.100.61/foo" srcText="foo.bar=XPLACEHOLDERX" echo $srcText | sed "s/XPLACEHOLDERX/$connect"   The result is:  sed: -e Expression #1, Character 32: Unknown option for `s'


Details: SNES, Cartridge reads III But apparently its VI Since I'm in America. I've just got to South Figaro (Not my first run) And I need a place to grind so I don't get my ass kicked on Mt. Kolts. (I'm keeping locke dead until I get Odin.)

I'm not to the World of Ruin yet and I want to level up, can anyone tell a good place to grind?


I am a bit confused with the D&D 5e Starter Set. I'm fairly new to the game.   In the character sheets, I am confused of what dice I use for damage rolls and what the modifiers are?   Is it the one listed under attacks and spellcasting?

I'm building my character, a Half-Elf Ranger, and I'm a little confused about how to work out the attack bonus and the damage bonus.  So, please tell me if I've got this right:   I'm proficient with a longbow. That means my attack roll is 1d20 + prof bonus + Dex modifier. The damage roll however is 1d8 + Dex modifier.   I'm just a little confused about working out the numbers (without even going into spells and when to roll for attack, etc.)


All of my pictures come out super blurry if they are anything bigger that 5x7 and I want to fix it. So how do I change the resolution? Is it something I have to do BEFORE I take the pictures or am I able to do it after? I need help! Thank you!

When setting image quality in my Canon EOS 1200d dSLR there are two options for the L, M and S1 size. What is the difference betwen these settings (I couldn't find it in camera documentation) ?


I need to check whether my email address has valid host, exist for example someone@yahoo.com might return valid meanwhile some@yahozzz.com might return invalid (because invalid host)  I stumbled upon a code in git for golang that satisfy my needs for that , but currently at the moment i'm looking for the solution in javascipt, any help will be appreciated.  P.S. : I am using this code as a script inside my HTML

I would like to use client-side Javascript to perform a DNS lookup (hostname to IP address) as seen from the client's computer. Is that possible?


The problem is in using the \multirow function. This is not the main document, the \usepackage{multirow} is already defined in the main document from which I compile. I can not see the error:  \begin{tabular}{|c|c|c|c|c|c|}  %\caption{Types of UAS according to NATO Classification}\\  \hline  \textbf{Class} & \textbf{Category} & \textbf{Normal employment}& \textbf{Normal Operating     Altitude}& \textbf{Normal Mission Radius} & \textbf{Example platform}\\  \hline   \multirow{3}{|l|}{Class I (less than $150$ kg)} & Small $>20$ kg & T & Up to 5000 $ft$ & 50 $km$ & Hermes 90, Luna\\  \hline  Mini 2-20 $kg$ & Tactical Sub-Unit & Up to 3000 $ft$ & 25 $km$ & AlDIN, dh3, DRAC, Eagle,   Raven\\  \hline  MICRO $<2$ $kg$ & Tactical PI (single operator) & Up to 200 $ft$ & 5 $km$ & Black Widow\\  \hline  Class II & Tactical & Tactical Formation & Up to 10.000 $ft$ & 200 $km$ & Aerostar, Hermes 450, iView 250, Ranger\\  \hline  \multirow{3}{|l|}{Class III ($>600 kg$)} & Strike/Combat &Strategic/National&Up to 65.000 $ft$ & Unlimited & bg\\  \hline  HALE (High Altitude Long Endurance) & Strategic & Up to 65.000 ft & Unlimited & Global Hawk\\  \hline  MALE (Medium Altitude Long Endurance) & Operational & Up to 45.000 ft & Unlimited & Predator B, Predator A, Harfang Heron\\  \hline  \end{tabular}

I'm trying to create the following table. This is the code which I wrote.   \begin{table}[!htb] \centering \caption{"table1"} \begin{tabular}{|c|c|c|c|c|c|c|c|} System & \multicolumn{2}{c}{Interaction} & \multicolumn{2}{c}{Commit} & Ver & LOC & terms \\\hline \multirow{3}{c}{System1} & \multicolumn{2}{c}{3272 traces} & \multicolumn{2}{c}{5093 revisions} & \multirow{3}{c}{3.4} & \multirow{3}{c}{1700} & \multirow{3}{c}{2400} \\\hline & File & Method & File & Method & & & \\\hline & 12 & 13 & 14 & 15 & & & \\\hline  \end{tabular} \end{table}   and this the error that Latex shows:! Missing number, treated as zero.!


I have a matrix whose elements belong to two different classes, and I need to distinguish them by color. Something like this figure:   Any tutorial or instruction?

I have a matrix and need to highlight some elements in the matrix. I have found how to highlight a single element (I want to put the cell in the square):  $$ A = \begin{bmatrix} \fbox{0} & \fbox{0} & 0 \\  \fbox{0} & \fbox{0} & 0 \\ 1 & 1 & 1 \\  \end{bmatrix}$$   But how can I outline elements of the submatrix like in the picture below? I need just a frame where some elements are located.


I have my own an organization and i want to replace some system with ubuntu, do i have to buy ubuntu? Because i have heard ubuntu is free for use!!  Thanks ITTECH

Is  free for business platforms?  Has Ubuntu changed its conditions about using the OS for profit purposes?


I have installed Scilab with sudo apt-get install scilab, and all went good until I tried to open the software, it just does not open, what I tried to do was install a new version of Java, and it make it kind of work, when I start it from the console like this:   cd /usr/bin ./scilab    but it still having some kind of trouble, I want it to start with the icon, but it looks to be impossible, please help me.   Warning: Could not find Java package '/usr/share/java/jlatexmath-fop-1.0.6.jar'. Some problems during the loading of the Java libraries occurred. This could lead to inconsistent behaviours. Please check SCI/etc/classpath.xml. Gtk-Message: 00:21:02.501: Failed to load module "canberra-gtk-module"   also I tried to install the 6.0.1 version of Scilab from the page, but at the moment of opening Scilab from the bin folder, a error comes up, saying that Scilab can not make the main class of Scilab :/ heelp

I have installed clean Ubuntu MATE 18.04 LTS and installed Scilab from repository here with    sudo apt-get update sudo apt-get install scilab   After installation I tried to launch it from GUI (Applications → Other → Scilab) - it does not start. Then I tried to launch it from terminal with scilab command. Terminal output is as follows:  $ scilab /usr/bin/scilab-bin: error while loading shared libraries: libjava.so: cannot open shared object file: No such file or directory   so it can't find Java. I reported  about this problem.  I checked existence of libjava.so:  $ dpkg -S libjava.so   openjdk-11-jre-headless:amd64: /usr/lib/jvm/java-11-openjdk-amd64/lib/libjava.so   so it is in place.  What should I do to get Scilab 6.0.1 working on Ubuntu 18.04 LTS?