In the Android project in which I'm working on now, object serialization is used for store the activation status. In it a Device object is created and all the data relevant to the activation are stored in it and the object is stored in a file on the memory. At this point the serialization comes to the scene and the object is serialized and stored in a file. So what is serialization, and what does that word mean actually? Is it a best practice regarding the security? Can't I store an object in a file directly?


How to break down a sentence of string  type into words and store it in a vector of string type in c++? Example  String str="my name";   Into  Vector word={" my","name"}


How to choose a smarthost based on From: address in exim4 on Debian

I want to route emails with the From: .*@host1.com through smtp.server1.com and emails with the From: .*@host2.com through smtp.server2.com.  For the moment, I have smarthost configured with dpkg-reconfigure exim4-config so that update-exim4.conf.conf contains the line  dc_smarthost='smtp.server1.com::587'. That is, everything routes through smtp.server1.com.  I tried adding another router just before the definition of smarthost: in the config file, setting senders = .*@host2.com  smarthost_server2:   debug_print = "R: smarthost_server2 for $local_part@$domain"   driver = manualroute   domains = ! +local_domains   transport = remote_smtp_smarthost   senders = .*@host2.com   route_list = * smtp.server2.com byname   host_find_failed = ignore   same_domain_copy_routing = yes no_more   but exim still routes everyting via smtp.server1.com. Do I use the senders condition correctly?  AFAIU, this should be a rather common setup for cases when people with emails .@google.com and .@gmail.com do not want to reveal in their @gmail.com email headers the fact that they are also google employees, so the routhing should be different.


Interpretation of Standard Deviation independent of the distribution?

Is there any intuitive way to interpret the standard deviation regardless of the probability distribution?  So for example, for the normal distribution, I know how to interpret being within 1 standard deviation - there is a a 68% of being there. For other distributions I can calculate this probability as well.  But if I don't know the distribution, how is it a meaningful statistic? Is it only meaningful in relation to other random variables that we know follow the same distribution, but have a different standard deviation?


Windows chkdsk replaced bad cluster - are files now corrupted?

I ran chkdsk on a drive and when it got to stage 4 (verifying file data), this message appeared for some files:  Windows replaced bad clusters in file ###### of name \path\filename.ext   Does this mean that these files are now corrupt?  I'm mainly concerned about ISOs and executables.  Unfortunately, I don't have hashes of them so I have nothing to check their integrity against after chkdsk finishes running.  If it's relevant, this is a mechanical hard drive, a 2TB Western Digital Green.


Prove that $H$ is a abelian subgroup of odd order

Question is:     Let $G$ be a group of  order 2n. Suppose half of the element of G are of order 2 and the other half form  a subgroup $H$ of order n . Prove that $H$ is of odd order  and is an abelian subgroup of $G$   What could i see is..  if we prove that order of every element of $H$ is odd , then order of $H$ is odd . Also i am unable to use the fact that half of the element of $G$ are of order 2.  Please help me to clear this.  Thank You.


Dominoes and induction, or how does induction work?

I've never really understood why math induction is supposed to work.  You have these 3 steps:   Prove true for base case (n=0 or 1 or whatever) Assume true for n=k.  Call this the induction hypothesis. Prove true for n=k+1, somewhere using the induction hypothesis in your proof.   In my experience the proof is usually algebraic, and you just manipulate the problem until you get the induction hypothesis to appear.  If you can do that and it works out, then you say the proof holds.  Here's one I just worked out,  Show $\displaystyle\lim_{x\to\infty} \frac{(\ln x)^n}{x} = 0$  So you go:   Use L'Hospital's rule. $\displaystyle\lim_{x\to\infty} \frac{\ln x}{x} = 0$. Since that's $\displaystyle\lim_{x\to\infty} \frac{1}{x} = 0$. Assume true for $n=k$. $\displaystyle\lim_{x\to\infty} \frac{(\ln x)^k}{x} = 0$. Prove true for $n=k+1$.  You get $\displaystyle\lim_{x\to\infty} \frac{(\ln x)^{k+1}}{x} = 0.$   Use L'Hospital again: $\displaystyle\lim_{x\to\infty} \frac{(k+1)(\ln x)^{k}}{x} = 0$.  Then you see the induction hypothesis appear, and you can say this is equal to $0$.  What I'm not comfortable with is this idea that you can just assume something to be true ($n=k$), then based on that assumption, form a proof for $n=k+1$ case.  I don't see how you can use something you've assumed to be true to prove something else to be true.


Format c# textbox to only allow numeric characters

I've been going through solutions from  here and dotnetperls to try and find a way to format my textbox to only allow numeric characters. I'm either just not getting it, or really don't understand the code to do what I want.  I have a form that changes depending on which button was pressed in another form, and I need the Age box to only allow numerical characters up to 99 (So the user can enter an age in the range of 1-99. I've looked into Regex methods and masked text boxes but just don't get it.  Would someone be able to point me in the direction of what I would use to achieve this?  My code reads as:  private void AddItem_Load(object sender, EventArgs e)     {         if (formName == "customer")         {             this.Text = "Add Customer";             lblZero.Text = "ID:";             lblOne.Text = "Customer Name:";             lblTwo.Text = "Address Line 1:";             lblThree.Text = "Address Line 2:";             lblFour.Text = "Town:";             lblFive.Text = "Postcode:";             lblSix.Text = "Age:";              txtID.Text = Convert.ToString(customerList.NewID());             txtID.Enabled = false;          }         else         {             this.Text = "Add Product";             lblZero.Text = "Product ID:";             lblOne.Text = "Product Code:";             lblTwo.Text = "Product Name:";             lblThree.Text = "Product Description:";             lblFour.Text = "Price:";             lblFive.Text = " --------- ";             lblSix.Text = " ---------";              txtID.Text = Convert.ToString(productList.NewID());             txtID.Enabled = false;             txtFive.Enabled = false;             txtSix.Enabled = false;          }     }   where the textboxes on the form are labelled  txtZero.txt ~ txtSix.txt.  All help is much appreciated :)


I'm seeking for a proof of the following:     Let $A$ be an invertible matrix. Then the determinant of $A^{-1}$ equals:   $$\left|A^{-1}\right|=|A|^{-1} $$   I don't know where to begin the proof. Any suggestions?


Was the first Leto II born with prescience?

The first Leto II dies towards the end of book 1 in the Dune series of book and very little is said about him but is it me tines anywhere if he has 'prescience'? He was half Fremen and the son of Muad'dib, although Chani wasn't in the high spice diet she was for the twins in book 2, but was he too young to show any signs?


grep to a file from one server to another

I have a grep command like below  zgrep '123_ERROR' xyz.gz   I got lot of huge results where I cannot see top part.  So what is best way to see entire result  how to export results to a file  zgrep '123_ERROR' xyz.gz>>/home/test/testfile.txt   i used above command but i do not seem to have permission to create testfile.txt  how to create above file in one other server whose ip is say 111.1.111.111


Who hid the collection of ancient Jedi texts in the millenium falcon? Did Yoda know about them when he destroyed the tree?

In the film's close moment we can see that Rey possesses the books, as they are stowed away on the Millennium Falcon. But did she put them there?  Did Yoda know something about it? And why didn't anyone tell Luke about them?


How do we know that the number $1$ is not equal to the number $-1$? (I am not talking about the multiplicative inverse of an arbitrary field, but the integer/rational, real or complex number $1$.) Is that an axiom? Since someone in the comments asked for more background/motivation: I'm just a naive bachelor student and I wanted to prove that for any number $x$, $x=-x$ implies $x=0$ (which is true if and only if $1\neq -1$, see ). Why is this question different to the question in my last post? In my last post, I wanted to know if you can prove that $x=-x$ implies $x=0$ for an element $x$ of an arbitary field. It turned out that you can not (there are fields where this is not the case). In addition, it turned out that this is true if and only if $1\neq -1$. ($1$ stands for the multiplicative identity, not the number one.) Since we normally assume that $x=-x$ implies $x=0$ if $x$ for some number $x$ (at least in my lectures), I wanted to know wheter you can prove that $1\neq -1$ or not. (To be honest, I didn't think that you have to distinguish e.g. between the integer $1$ and the natural number $1$...) To put it into a nutshell: My first question was wheter you can prove $1\neq-1$ where $1$ stands for the multiplicative identity of an arbitrary field (the answer is no.) But we know that the answer is yes if $1$ stands for the integer/real number/complex number one, which led to this post.


How do I get random number in the range st 1 to 45 only (not included zero). Here is my code so far:  int number;  Random randomNum = new Random();  number = randomNum.nextInt(45)+1;  for (int y = 0; y < 10; y++) {      System.out.println("");      for (int i = 1; i <=6; i++) {          number= randomNum.nextInt(45);          if (i==6) {             System.out.printf("%d",number);         }         else {             System.out.printf("%d-",number);         }     } }


Proof Verification: Classify all groups of order 6

I'm currently in an introductory group theory class, and I'm supposed to classify all groups of order 6 up to isomorphism without use of more advanced concepts like the Sylow theorems or even the Cauchy theorems. Can someone help check my proof? I'm trying to be as thorough as possible, so I apologize if it's a little bit long-winded.  There are only two groups of order 6 up to isomorphism, the cylic group $\langle \mathbb{Z}_6 \ |\  +\rangle $ and the symmetric group $\langle S_3 \ | \ \circ \rangle $. We prove this by proving the 2 following statements:   If $G$ is abelian, then $G \cong \mathbb{Z}_6$ If $G$ is nonabelian, then $G \cong S_3$   To prove the first statement, we suppose for sake of contradiction that all nonidentity elements have an order of 2. Since $|G| = 6$, there are 5 nonidentity elements. Choose 2 distinct nonidentity elements, $x,y,$ and consider that necessarily $x^2 = y^2 = e$. We have that $G$ is abelian, so the set $H = \{e, x, y, xy \}$ is a subgroup of $G$. However this contradicts Lagrange's Theorem, because $4 \nmid 6$. Thus there are elements of $G$ which are of order 3 or 6.  If $G$ has an element of order 6, then $G$ is cyclic, and $G \cong \mathbb{Z}_6$. If $G$ has an element of order 3, say $z$, then $|xy| = 6$. (is this step ok?) Again, $G$ is cyclic, so $G \cong Z_{6}$.  \  For the second statement, we briefly pause to show that $G$, being a group of an even order, must have an element of order 2. This is because all elements with order larger than 2 must have an inverse of the same order, so there are an even number of such elements. But $G$ has an even order, and hence an odd number of nonidentity elements, so there is an element of order 2.   We notice that the nonidentity elements of $G$ must be of order $2, 3 $ or $6$. $G$ cannot have an element of order 6 because $a \in G, |a| = 6 \implies G = \langle a \rangle $ implies $G$ is cyclic and therefore abelian. Furthermore by the logic given above, $G$ cannot have all nonidentity elements of order 2, because $G$ would again be abelian. So then there exists $a \in G, |a| = 3$. Now take another nonidentity element, $b$, such that $b \not \in \langle a \rangle $. Again, we can do this because there are 5 nonidentity elements and $\langle a \rangle $ would be only 2 of them. Consider $|\langle a \rangle  \cap \langle b \rangle|$:   If $|\langle a \rangle  \cap \langle b \rangle| = 1$, then the cycles generated by $a$ and  $b$ have no overlap except for the identity element. $|\langle a \rangle  \cap \langle b \rangle| = 2$ is not possible, since if $|b| = 2$ then $b \in \langle a \rangle $, but $b$ was chosen specifically so that $b \not \in \langle a \rangle$. $|b| = 3$ would also not be possible because $|b| =3$ implies $| \langle a \rangle  \langle b \rangle | = 9$, which contradicts Lagrange's Theorem.  $|\langle a \rangle  \cap \langle b \rangle| = 3$ is not possible, since it implies $|b| = 3$, and then $| \langle a \rangle  \langle b \rangle | = 9$ contradicts Lagrange's Theorem.   Thus  $|\langle a \rangle  \cap \langle b \rangle| = 1$ and $|b| = 2$. We then have the 6 elements of $G$ as being $\{ e, a, a^2, b, ba, ba^2\} = \langle a \rangle \cup \langle b \rangle $. Now consider $ab$.   $ab \neq e$, since $b \not \in \langle a \rangle $ $ab \neq a$, since $b \neq e$ $ab \neq b$, since $a \neq e$ $ab \neq a^2$, since $b \neq a$ $ab \neq ba$, since $G$ is nonabelian $ab = ba^2$ is the only remaining possibility.   As a result, $G = \langle a, b \mid a^3 = e, b^2 = e, ab = ba^2 \rangle $. This is the same group presentation as for $S_3$, hence $G \cong S_3$


Steam Install Error on 14.04 Ubuntu 64bit

I have tried some of the solutions posted elsewhere in the support forum, one seemed like it worked but after a steam update i found myself back at square one  I am a new Linux user and am already at a learning curve :)  Thanks for any help  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  libgl1-mesa-glx:i386 : Depends: libglapi-mesa:i386 (= 10.1.3-0ubuntu0.3)  unity-control-center : Depends: libcheese-gtk23 (>= 3.4.0) but it is not going to be installed                         Depends: libcheese7 (>= 3.0.1) but it is not going to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. Press return to continue:


How can I start a VM without getting a window?

VirtualBox has a window showing the display of the guest OS. I am connecting to VirtualBox with Remote Desktop, so I don't need VirtualBox to show that window in the host OS.   Of course, I can minimize it, but is there a way to tell VirtualBox not to display that window?


Why is the dynamic pressure not a vector quantity?

I understand that static pressure is a scalar quantity as it acts equally in all directions, then by the same reasoning dynamic pressure should be a vector quantity as it only can be measured by opposing the flow.  I understand that the act of opposing the flow will instantly convert dynamic to static but I am asking in theory?   Thanks all the answers ( @Nikos M. ) and assistance , However I am still unclear as to why dynamic pressure (at any instant) is not thought of to be a force acting in a specific direction (perhaps vector is not the right term ?)


Find generators of the ideal of an algebraic set

The following exercise comes from Fulton's Algebraic Curves:     Let $k$ be an infinite field and $V = \{(t,t^2,t^3) \, ; \, t \in k \} \subset \mathbb{A}^3(k)$. Show that $V$ is algebraic and compute $I(V)$ by giving a finite set of generators.   Now, showing $V$ is algebraic is easy by noting that $V = V(X^2-Y, X^3-Z)$, but I can't find a way to describe $I(V)$ explicitly. Obviously $(X^2-Y)(X^3-Z) \in V$, but how can I find the actual generators of this ideal?


Im new to Blender, and want to try out making a game character.  My question is, is scultping easier to do? And when I sculpt a model, do I HAVE to do the retopology after to make it animated, or is that just something some people prefer to do?  Thanks! :)


Evaluate : $\lim_{n\to \infty}\{(1+\frac{1}{2n})(1+\frac{3}{2n})(1+\frac{5}{2n})\cdots (1+\frac{2n-1}{2n})\}^{\frac{1}{2n}}$ My attempt : Since, [$\displaystyle \lim\limits_{n\to \infty} a_n^{1/n} = \lim\limits_{n\to \infty} \frac{a_{n+1}}{a_n}$] $$Here \ \ a_n = \prod\limits_{k=1}^{n} \left(1+\frac{2k-1}{2n}\right) $$ I got $$\frac{ a_{n+1}}{a_n}=\frac{(4n+1)(4n+3)}{(2n+1)(2n+2)\times (1+\frac{1}{n})^n}$$ $$\ Hence, \ \lim\limits _{n\to \infty} {\frac {a_{n+1}}{a_n}}=\frac{4}{e} $$ My question is can I still use Cauchy's second theorem if the power of the function is $\frac{1}{2n}$? Caused I've solved it same as the power  $\frac{1}{n}$. Please help me for this. Thank you in advance.


I am trying to check if node "DEF" exists in my xml file  My xml file looks like this:  <Struct>    <A>       <ABC>       </ABC>       <DEF>       </DEF>    </A>    <B>       <GHI>       </GHI>    </B> </Struct>   And my code looks like this:  XmlDocument stru = new XmlDocument(); stru.Load(path + "Structure.xml"); if (stru.ChildNodes[0].HasChildNodes) {     for (int i = 0; i < stru.ChildNodes[0].ChildNodes.Count; i++)     {         if (stru.ChildNodes[0].ChildNodes[i].Attributes["DEF"] != null)         {             enabled = true;             break;         }         else         {             MessageBox.Show("no");         }      } } else { MessageBox.Show("Error!"); }   And it immediately shows messagebox with "Error!" in it


Counting TOTAL number of rows in the tables of a database

I would like to know how to Count the TOTAL number of rows in the tables of a database. For example, I have 3 tables in a database called:  Table 1: 5 rows  Table 2: 4 rows  Table 3: 3 rows  So the output should be: 12 rows.   I know how to count rows in a specific table. Is there something to loop here?  Thanks.


Call Fragment Method in an Activity getting NPE

I would like to call method of MainFragment.java from MainActivity.java  Here what I have tried:  MainActivity.java  MainFragment mainFragment;  ........  mainFragment = new MainFragment();  .........  mainFragment.deom();   MainFragment.java  public void deom() {      Toast.makeText(getActivity(), "Demo", Toast.LENGTH_LONG).show();  }   Log  java.lang.NullPointerException at android.widget.Toast.<init>(Toast.java:93) at android.widget.Toast.makeText(Toast.java:241) at com.example.x.b(Unknown Source) at com.example.MainActivity.onOptionsItemSelected(Unknown Source) at android.app.Activity.onMenuItemSelected(Activity.java:2633) at android.support.v4.b.ao.onMenuItemSelected(Unknown Source) at android.support.v7.app.t.onMenuItemSelected(Unknown Source) at android.support.v7.view.n.onMenuItemSelected(Unknown Source) at android.support.v7.view.n.onMenuItemSelected(Unknown Source)   May I know where I am doing mistake ? What I have missed ? Why I am getting NPE.


Using an ellipsis to show omission, when we skip complete sentences. 3 or 4 dots?

Imagine I want to quote this text (the parts in bold):     If there were such a thing, I think I'd be a champion. You know, baking under dangerous conditions, high-speed frosting... all hypothetical examples, obviously. Of course assuming I don't live in a madhouse.   Should I quote it with 4 dots, because I'm skipping a full sentence?     If there were such a thing, I think I'd be a champion. . . . Of course assuming I don't live in a madhouse.


Scheduling a Batch job at a particular time

I have a Apex batch class which I would like to schedule at a particular date time. The date time is stored in a variable and changes dynamically. ex Datatime scduleDateTime = datetime.now() ; I want to schedule the apex batch file to run at this datetime variable value.  How can I do that using system.scheduleBatch()  I started with this but could'nt see how I can specify a datetime variable in here:  datetime d = datetime.now(); sampleapexbatch b = new sampleapexbatch(d); System.scheduleBatch(b,'Sample Job',XXXXXXXX)   Any help is appreciated!


Identify a short story where two astronauts on an orbiting platform are having a dispute

I remember reading a short story in the 60/70's where there were two astronauts in spacesuits on an orbiting platform having some sort of dispute. One of them successfully threatens the other to by hurling him towards the planet whereby he believes that he doomed to keep falling. It turns out, however, that following orbital mechanics ( conservation of the center of gravity ) that the hapless astronaut will rejoin the platform halfway through the revolution. I thought this was a Clark or Asimov since it involved some real physics but I can't seem to locate the title.


Is it ok to place help icon inside modal windows? Is there is any UX reason that this would not work?

I have a Scenario, were I need to place help icon inside a modal window, Even though I have help icon on screen i.e... behind modal window. Is it is ok to have Help icon inside modal window, If not is there is any good reason for not to have that inside modal window.


How to use Windows US-Intl keyboard layout on a Mac?

Windows, Linux, ChromeOS, etc. all have a keyboard layout called US International, which turns the right Alt key into a modifer that lets you type common symbols from European languages, as well as adding various dead keys.   Is there any way to use this keyboard layout on a Mac? Macs do have a layout called "U.S. International - PC", but despite the name, it doesn't match the keyboard layout used on other OSes. It makes " and ' combine with certain letters but otherwise doesn't appear to change anything at all and in particular, holding the right Alt key doesn't work.  I don't want to have to memorize a whole different keyboard layout just for Macs, or hold each key and wait for a popup or whatever.  The Alt level of Windows US International, which I am used to looks like this:    But the same level on Apple's US International PC is a lot different and looks like this:


I am creating an application using Xamarin.Forms. I am trying to access each element in the list of MovieRent instances. I have a class that stores movie information:   public class MovieRent     {         public string movieTitle { get; set; }         public string movieReleaseDate { get; set; }         public int movieDuration { get; set; }         public double movieRentalPrice { get; set; }         public string movieRentType { get; set; }          public MovieRent(string mtitle, string mdate, int mtime, double mprice, string type)         {             movieTitle = mtitle;             movieReleaseDate = mdate;             movieDuration = mtime;             movieRentalPrice = mprice;             movieRentType = type;         }     }   addCartList is called to add a movie to a list. This creates/stores a list of movies.    class MoviesToRent     {         public List<MovieRent> movieRentList;         public MoviesToRent()         {             movieRentList = new List<MovieRent>();         }          public static MoviesToRent addCartList(string title, string date, int duration, double price, string type)         {             MoviesToRent movieList = new MoviesToRent();              MovieRentnewMovie = new MovieRent(title, date, duration, price, type);              movieList.movieRentList.Add(newMovie);              return movieList;         }     }   I am trying to access each instance, for example, the title of each movie in the list:  foreach (string movie in MoviesToRent.movieRentList)  {    this.Movie_Info.Text = movieRentList.title; }   However, I get this error:     An object reference is required for the nonstatic field, method, or   property 'MoviesToRent.movieRentList'.   How can I overcome this error, so that I can access the movies that are in the list? I am trying display all movie info by looping through the list. Thank you.


The following exercise is from the book of Churchill of complex analysis. Solve the integral $$\int_0^\infty \frac{x^a}{(x^2+1)^2}dx$$ where $-1<a<3$ the book of complex analysis of Churchill suggests the indented countour:  And also the book gives you the answer $\frac{\pi(1-a)}{4\cos(a\pi/2)}$. Progress: I did $\int_\Gamma \frac{z^a}{(z^2+1)}dz$ where $\Gamma$ is the region above. I already have $$\int_\Gamma \frac{z^a}{(z^2+1)^2}dz=\frac{i\pi e^{ai\pi/2}(1-a)}{2},$$ $$\int_\Gamma \frac{z^a}{(z^2+1)^2}dz=\int_{-R}^{-r} \frac{z^a}{(z^2+1)^2}dz+\int_r^R \frac{z^a}{(z^2+1)^2}dz-\int_{C_r} \frac{z^a}{(z^2+1)^2}dz+\int_{C_R} \frac{z^a}{(z^2+1)^2}dz.$$ $$\lim_{R\rightarrow\infty}\int_{C_R} \frac{z^a}{(z^2+1)^2}dz=0.$$ and $$\lim_{R\rightarrow\infty,r\rightarrow 0}\left(\int_{-R}^{-r} \frac{z^a}{(z^2+1)^2}dz+\int_r^R \frac{z^a}{(z^2+1)^2}dz\right)=(1+(-1)^a)\int_0^\infty\frac{z^a}{(z^2+1)^2}dz=(1+e^{i\pi a})\int_0^\infty\frac{z^a}{(z^2+1)^2}dz$$ So I get $$\int_0^\infty\frac{z^a}{(z^2+1)^2}dz=\frac{\pi(1-a)}{4\cos(a\pi/2)}+\lim_{r\rightarrow 0}\int_{C_r} \frac{z^a}{(z^2+1)^2}dz.$$ Where $C_R$ is the upper semicircle of radius $R$ with positive orientation and $C_r$ is the upper semicircle of radius $r$ with positive orientation. So that tells me it must happen that $$\lim_{r\rightarrow 0}\int_{C_r} \frac{z^a}{(z^2+1)^2}dz=0,$$ but I haven't been able to prove it, I have tried to use Jordan's lemma doing a change of variable, integrating and using L'Hopital and I don't get that this integral converges to $0$. Does somebody knows how to achieve it?


I tried installing Ubuntu (successfully) on my Windows 8 machine so i could develop in c and it worked decently for a while. I did this without wubi. However, I later got a virtual machine to run Ubuntu and didn't need the full dual boot install anymore. Following a guide I found online (I dont remember where), I simply deleted the 2 Ubuntu partitions (1 was a main partition and the other was a swap area). When I rebooted my computer I was greeted with a grub rescue prompt. I have tried using  both Ubuntu's boot-repair (but only on recommended settings since I am kind of afraid to mess around with options I don't know about) and boot repair from my Windows install disk (both the automated repair and the bootrec command line options). The linux boot repair said it completed successfully but gave me a warning midway through which said something like "EFI detected. check the options." The both Windows boot fixes said they completed successfully. I have also tried using supergrub to fix my bootloader. All of these wind up back at the grub rescue prompt.   Things that make this complicated: I have a lenovo y580 laptop which comes with 2 disks: a 30gb ssd (I was told this was for booting and caching) and a 750 gb hdd. The computer also came with Windows 7. I have since replaced the hdd with a 250gb ssd. and upgraded to Windows 8. As a result I am not entirely sure which drive Windows 8 is stored on. can anyone help me fix my boot?  UPDATE: after trying to run Windows bootrec commands again bootrec /fixmbr completes sucessfully, but bootrec /fixboot fails because "Element not found."


It is said that charge is a property of fundamental matter but mass is also property of matter even we can realize the term mass i.e. it indicates how hard it is to drag a matter. What kind of property charge is and who gave the the concept of of charge and why it is called charge?


Arcpy 64 bit, or multiple Python installs?

I am new to Python, and am trying to write a script that would upload a geodatabase to AGOL at a scheduled interval. However, the 32 bit distribution of Python cannot handle the file size (over 1 MB), even when the multipart parameter of addItem (using ArcREST) is set to true. Through some investigation, I've learned that this is a limitation of Python32, and to do what I'd like to do I need the 64 bit version. I was trying to avoid having multiple installs of Python (as I said, I'm new to it, so the less complication, the better), but if I remove Python as it was installed with ArcGIS, I lose Arcpy, which I also need. So, my question is, does anyone know of a solution to this issue, or am I stuck dealing with multiple Python installs?


How to type this symbol in LaTeX (commonly used to denote a sector)?

I'm sorry to ask such an elementary question. I am wanting to know how to type the following symbol in LaTeX, it is written with a subscript 'l' in the image below,     I feel quite illiterate because I don't even know how to read this symbol. I have tried typing the (English) alphabet in various font styles but nothing matched.   Many thanks


Let $a_1,a_2,\cdots,a_n$ be $n$ numbers such that $a_i$ is either $1$ or $-1$.If $a_1a_2a_3a_4+\cdots+a_na_1a_2a_3=0$ then prove that $4\mid n$.

Let $a_1,a_2,\cdots,a_n$ be $n$ numbers  such that $a_i$ is either $1$ or $-1$. If $$a_1a_2a_3a_4+a_2a_3a_4a_5+\cdots+a_na_1a_2a_3=0$$    then prove that $4 \mid n$.   My work: By multiplying all the terms, we get, $$a_1^4a_2^4\ldots a_n^4=1.$$  I think that I will be able to represent $4n$ a power of $1$, but getting no clue. Please help! I also think that this problem can be done with invariance and extremal principal too. Please help with these approaches too!


The square of an integer has form $3n$ or $3n+1$

Prove that if $n\in\mathbb Z$, then $n^2$ is of the form $3q$ or $3q+1$ for some $q\in\mathbb Z$  I would like to show that 3q+2 is = 3q+1 thus $n^2$ can be of the form of 3q or 3q+1.  Case one   $(3k)^2=(3k)(3k)=9k^2=3(3k^2)$ and is still of the form $3q$  When $q=3k^2$  $3q$  Case two  $(3k+1)^2= (3k+1)(3k+1)= 9k^2+6k+1$  $(9k^2+6k)+1 =3(3k^2+2k)+1$ this is of the form $3q+1$ when $q=3k^2+2k$  $3q+1$  Case three  $(3k+2)^2= (3k+2)(3k+2) =9k^2+12k+4$  $(9k^2+12k+4) = 3(3k^2+4k+1)+1$  This is of the form $3q+1$ when $q=3k^2+4k+1$  $3q+1$  using a direct proof with cases we see that when $n$ is of the form $3k$ it's in the form $3q$ after squaring. Also when n is in the form $3k+1$, $n$ squared is still in the form $3q+1$ after squaring. Lastly we saw that when $n$ was in the form $3k+2$ we could simplify to the form $3q+1$.


On latest version Ubuntu 14.04 LTS, I have tried this :  sudo apt-get install yum   Then it says :  sudo password for user   And nothing gonna happen , if hit enter 3 times it says 3x incorrect attempt.  I'm beginner to Linux


Why would my dad sign as the buyer while I sign as the co buyer?

I am extremely confused why the dealership had my dad sign as the primary buyer and me as the co buyer. I understand that we both have equal rights to the car and have an equal obligation to pay for this loan. I made sure to ask the guy not once, but twice if I was the buyer of the car , meaning that I would be responsible for everything, not my dad. He assured me that yes I would be the buyer. He neglected to tell me as a first time car buyer how this would affect my father if he signed on with me. It is only after my dad had issues with refinancing the house that he got denied because he signed on with me as a buyer of a vehicle. Please help me understand!


I just decided to give a try to Ubuntu 17.10, but as soon as I tried to set my compose Key, I can't find the place to do it.  Usually it was in Settings > Devices > Keyboard > Typing, but in this section I only find two options:  Switch to next input source Switch to previous input source   Any ideas? Thanks in advance!


Why won't my change to the sshd_config file persist?

I am writing a script to modify settings on my Ubuntu server.  I have the following line in it:  sudo sed 's/PasswordAuthentication yes/PasswordAuthentication no/' /etc/ssh/sshd_config   The problem is that the change will not remain.  It simply changes the 'no' back to 'yes'.  When the command executes, the modified file immediately displays in the terminal showing the 'no', but when I cat the file or open it in vim it shows a 'yes' again.  Additionaly, I can open sshd_config in vim and modify it manually and the change remains just fine.  Any thoughts?  Thanks.


I had a question. I'm trying to get in to tabletop rpg games. I'm very new and the people that want to play with me are also very new. After some googling I stumbled on the D&D red box. This looked as a great way to learn d&d. (I was doubting about between d&d and pathfinder, went with the first because of the name and the assumption it would be "more supported").  I also read there was a nice path from the redbox, to the dm kit etc etc. Though now I find out the dm kit is still available, it is very expensive. (a bit too for me). My big question is, what is the way to continue now after the redbox (except for paying tons of money). Hope someone can give me some hints and tips.  Patrick


Strength of the statement "$\mathbb R$ has a Hamel basis over $\mathbb Q$"

I would like to know if there are "interesting" equivalences to the statement "$\mathbb R$ has a Hamel basis over $\mathbb Q$". I am not interested in more general statements, like "every vector space has a Hamel basis" or "every vector space over (your favorite field) has a Hamel basis".  On the other hand, according to , such Hamel basis of $\mathbb R$ over $\mathbb Q$ may not exist, assuming the negation of the Axiom of Choice. Where can I find a proof of this fact?


Let $G = GL_2\mathbb (R)$. Show that $T$ is a subgroup of $G$

Let $G = GL_2 (\mathbb {R} $).   Show that $T$ = {$     \begin{bmatrix}         a       & b \\     0       & d  \\      \end{bmatrix}$ | ad $\neq 0$ } is a subgroup of $G$  My attempt:  det$(TT^{-1})$ = det$(T)$ det($T^{-1})$ = det($T$)  $1$/det($T$) = $ad$ $(1/ad)$= $1$. We are done by subgroup test


Retrieve all Custom Metadata for a single type

Is it possible to somehow retrieve all metadata for a single custom metadata type via ant or sfdx mdapi ?   I've tried this:  <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Package xmlns="http://soap.sforce.com/2006/04/metadata">     <types>         <members>Env_Var__mdt.*</members>         <name>CustomMetadata</name>     </types>     <version>45.0</version> </Package>   but it doesn't work...  I know I can get EVERYTHING with <members>*</members> but that's not really helpful...


I don't know why my MWE is not work for some keywords  Here is my MWE  \documentclass{article}  \usepackage[outputdir=output]{minted} \usepackage[skins,minted]{tcolorbox}   \newtcblisting{bashcode}[1][]{     listing engine=minted,     colframe=black!70,     listing only,     minted style=colorful, % pygmentize -L styles     minted language=bash,     minted options={linenos=true,numbersep=3mm,texcl=true,#1},     left=5mm,enhanced,     overlay={\begin{tcbclipinterior}\fill[red!20!blue!20!white] (frame.south west)        rectangle ([xshift=5mm]frame.north west);\end{tcbclipinterior}} }  \begin{document}  \begin{bashcode}[] # test cd ~/temp mkdir latex-tests cd latex-tests mkdir output # For LaTeX compilation output \end{bashcode}  \end{document}


Calculating proportional area of polygon within another layer's polygon using QGIS?

I have two polygon layers, model and ntem, whose features overlap and intersect one another. I would like to calculate the proportion of the area of the model polygons which fit within each ntem polygon. Some model features fully fit within ntem features, others overlap multiple ntem features. Both layers are in CRS OSGB:1936.        For example, model feature 50209 falls partly in each of the three ntem features 2202, 2205, 2206 and I'd eventually like to know the proportion of 50209's area in each ntem area.  From initial research, I understand that the Vector > Geoprocessing Tools > Intersect function should do what I want, however I get a completely blank layer of results when I attempt this. (Shapefile is created, empty attribute table, no features!)  Can anyone either point out if I am doing something wrong and suggest an alternative method of achieving the area proportion calculation?


Virtualbox-5.1 - Shared Clipboard and Drag'n'Drop options not working

I have virtualbox 5.1 installed on Ubuntu 16.04 OS. I am using it to set up a Ubuntu 16.04 Virtual Machine.  I have set up the VM using a .iso file of Ubuntu 16.04. I installed the guest editions from the 'Device' drop down menu and have enabled 'Bidirectional' option in the settings for both Shared Clipboard and Drop'n'Drop options.   With these settings, I am unable to copy/paste or drop files from host to guest or vice-versa. How do I resolve this as I need this functionality to transfer important files.


I am looking for a simple method to change password with a script on macOS 10.12.6 (or newer).  I tried something like  sudo yes "mynewpassword" | sudo passwd myuser   But this is not working, apparently passwd is not reading from stdin.  I wonder if there is a official method to do so, like a command line tool.


Hi please am new to python coming from a visual basic .net framework. Trying to follow a tutorial on . There is a line of code i really don't understand. Please can someone explain it to me. Thanks   import time  from calendar import month_name  year, month = time.localtime()[:2]   The confusion for me is that the variable year and month is their value both time.localtime()[:2]. Any clarification will be highly appreciated.


What's a good idiom to describe someone who is very clever?

Is there an idiom to describe someone who is clever and quick-witted?


How can I prove this equation is correct?

$$ \left(\begin{array}{c}a+b\\ n\end{array}\right) = \sum_{i=0}^n \left(\begin{array}{c}a\\ k\end{array}\right) \left(\begin{array}{c}b\\ n-k\end{array}\right)$$


University policy of publishing student course evaluations: Prevalence and pros and cons

These days it is very common to have some course evaluation towards the end of a course, in which students respond to standardized questions on a numerical scale (e.g. between 1 and 5) and can additionally give free-form comments.  Sometimes individual lecturers make student comments (and their responses) available to the cohort in which the survey was taken and the next cohort, to show that they are open to critique and how they respond to it.  I am, however, more interested in cases where there is a departmental/faculty/university-wide policy to consistently publish evaluation results for all of their courses (averages of numerical data only, or perhaps the free-form comments as well) to the current and future cohorts.    Is it common for universities to have a policy of publishing student course evaluations?  What are advantages and disadvantages of doing this?  Has this been looked at in the educational literature?


I have learned EFA and CFA in SPSS/ AMOS and a basic understanding of why they work (but in a non-mathematical way, which makes me feel I might have some fundamental misconceptions, and hence this question). I wanted to know what are some good books/ lectures/ notes to learn the theoretical foundations of EFA and CFA, from beginner's to advanced levels of understanding. I know that might be a lot to learn, I plan to learn it as soon as possible, but would not mind if learning it too quickly is not possible, and would be grateful for resources that take longer to learn too. I am comfortable with UG level mathematics (in my final year currently).


GCC and G++ are one compiler ? or they are differents compilers?

Today I am starting to learn C++. And I have a question. But first I want to say that I searched the internet and I still haven't found the answer to my question. Please do not throw with dusty slippers in me. I am a beginner and my question is : Are C++ && G++ differents compilers or is it one compiler with many drivers for the programming languages? More precisely, for C and C ++. From what I understand, g++ is a driver for the C++ programming languages. But even here I vaguely understand what a driver for the C++ programming language is and why it is needed. In general, I'm confused. Could you kind people answer this question, because I can't understand? Please. And in the end, I want to say that maybe this question is stupid. But I'm just curious. Or am I not understanding something?


Do I need a resistor between the microcontroller and the battery?

I'm doing a university assignment and I need some advice. Do I need a resistor between the 9V power source and the microcontroller that uses 5.5V and 1mA? Also between a gyroscope sensor that uses 3V and 5mA?


Checking consecutive elements in a string array in java

I just started working with arrays.My code is supposed to keep asking for the user to enter words/alphabets.However,if the words entered are similar for 2 consecutive entries,the program should display a message as shown below.The following was my hypothesis to compare 2 consecutive string elements.However,my program does't work.       import java.util.*;  public class StringArrays {     public static void main(String[]args)     {          String[] list=new String[50];         for( int i=0;i<50;i++)          {               Scanner a=new Scanner(System.in);             System.out.println("Enter something: ");             list[i]=a.next();              if(list[i]==list[i+1])             {                 System.out.println("Stop!");              }             else             {                 System.out.println("Smart!Continue..");             }          }     } }   I'm just wondering what's the correct way to inspect 2 consecutive elements of a string array. Thanks for all your help :)


The challenge room is locked but I have full health

This question here:    says I should be able to open these challenge doors with full health. But I've had multiple instances where the room is locked even when I have completely full health. In fact, check this out, I started the level with full health, plus some, and I can't even get anymore! Look:    The challenge room is right there, I have full health, and this is how I started the level. What's the deal?


Why can higher order functions be declared without specifying that they need an input?

For if I wanted to make a higher order function that filters even numbers out of a list using the predefined filter function I can do it like this:  filtereven list = filter even list   but another thing that still works is:  filtereven = filter even   why does this work and how does it know that it should expect an input list?


I am trying to produce 3 matrices on the same line. And on top of the each matrix, there is a name. I tried using tabular for the names and then I use align for the matrices. However, this creates some kind of space between the names and the matrices, which I do not want. Is there a better way to do this ? I have seen other posts but they do not seem to solve my problem. Please note that I need to use bordermatrix because I need to label the rows and columns as well.   \begin{center} \begin{tabular}{ccc} Kay & Brian &  Edwin \\ \end{tabular} \end{center} \begin{align*} \bordermatrix{ & I & A \cr I &1 & 2 \cr A & 3 & 4 }  & \bordermatrix{ & I & A \cr I &5 & 6 \cr A & 7 & 8 }  & \bordermatrix{ & I & A \cr I &9 & 10 \cr A & 11 & 12 }  \end{align*}


I'm using the biblatex package with option backend=bibtex. However, AUCTeX C-c C-c suggests running biber. How can I have the backend detected correctly, or override this and configure AUCTeX to always run bibtex? (I actually already have the BibTeX command run a script that checks and runs either bibtex or biber as approriate.)


Why didn't my latest (well-received) question go towards my "Curious" badge?

I've posted my fifth well-received question:    However, I still seem to be stuck on 4 out of 5 for the Curious badge:    Any idea what I've done wrong?  This question is different from , because that question pertains to having more than five well-received questions and still not getting the badge. In my case, I seem to have five well-received questions but Stack Overflow is telling me I only have four out of five.


What does it mean if Data partition wiped out?

What if during flashing mark Data partition to be wiped out. Will it destroy all photos, media etc with no possibility to recover?


Best way to allow users to enter in information into a limited character cell in a table

Im creating a new feature to allow users to add a new comment field into their online table. For various technology reasons we are using a small modal when entering comments.  The comments will be limited to 250 characters (for other reasons). My question is:   Should i prevent users from entering in characters over 250? or Should i allow users to enter in characters over 250 but prevent them from submitting it and display characters which will not be submitted (similar to how twitter allows you to do this?)


How to install ubuntu server on HP 819185-421 proliant microserver?

I have bought a HP 819185-421 proliant microserver, and I want to install ubuntu server before buying hard disks. So, I burn Ubuntu 14.04 in a usb(4GB) using the software "ISO to USB", but after choosing the usb in the bios, it said "no OS found, please remove units without OS and reboot" (something like that, I do not remember the exacts words). I know that if I switch off the server, the usb does not save the configuration, but I only want to install the ubuntu server, make some test and after that, buy hard disk.  Thanks for all


ps aux | grep config vs ps aux | grep "confi[g]"

I would like to know why ps aux | grep includes the grep command in the output but ps aux | grep "confi[g]" does not.  $ ps aux | grep config root               50   0.0  0.0  2548368   5760   ??  Ss   14Sep16   0:29.27 /usr/libexec/configd emesa           20534   0.0  0.0  2434840    796 s002  S+    4:41PM   0:00.00 grep config   vs.  $ ps aux | grep "confi[g]" root            15776   0.0  0.0  2519824    940   ??  Ss   Tue11AM   0:00.08 /System/Library/PrivateFrameworks/SystemAdministration.framework/XPCServices/writeconfig.xpc/Contents/MacOS/writeconfig root               50   0.0  0.0  2547320   5740   ??  Ss   14Sep16   0:29.27 /usr/libexec/configd


Let $\displaystyle  f(x) = \begin{cases}e^{- \frac{1}{x^2}} &\text{for } x \neq 0     \\ 0 & \text{when } x=0 \end{cases}.$      Prove that $f$ has derivatives of all orders at $x=0$, and that $f^n(0)=0$ for $n=1,2,3,...$   I found this problem from Rudin's principles of Mathematical Analysis book (p.196). My problem is, can I use the formula $e^x=1+x+\frac{1}{2!}x^2+...$ and use directly Theorem 8.1 and Corollary on page 173 in the same book? If not can anyone please explain me the reason?


How do you create a dashed circle in blender?

How would you create a dashed circle in blender with an empty circle object? I want something that looks sort of like this:  Related:


If $X$ locally compact Hausdorff space. Then  $C_{c}(X)$ is complete implies $X$ is compact.  I know that $C_{c}(X)$ dense in $C_{0}(X)$. So in that case  $C_{c}(X)=C_{0}(X)$. I know only Tiez extension theorem on locally compact Hausdorff space and vary basic knowledge of Banach Algebra.


I just upgraded to Ubuntu 14.04 and I can't use my old keyboard layout configuration.  I used the Caps Lock key to change the layout to Hungarian. and I used the Shift+Caps Lock key to change the layout to English.  How can I set this keyboard shortcut in Ubuntu 14.04? All I can do is a previous source and next source option in All settings -> Keyboard -> Shortcuts -> Typing. But I don't know which was selected in most case, so I prefer start hit caps-lock before writing Hungarian, and Shift-CapsLock when I start programming. But now I can just rotate this sources (layouts) which is non-sense to me. I am not a finite state machine to remember my keyboard layout state.


What is the probability that this person really has the disease?

A test for a certain disease has a probability $\frac{4}{5}$ of detecting the disease when it ispresent and a probability of $\frac{1}{10}$ of falsely \detecting" it when it is not present.   The proportion of people afflicted by the disease for a given population is 15%.   If a person from the population is randomly selected and gives a positive result to the test, what is the probability that this person really has the disease? (Answer: 24/41).  I'm struggling to get that answer. I honestly just don't know how to approach this question.


How do I prove this graph is nonplanar? It has 11 vertices and 25 edges, with a girth of 3.


What is the purpose of the capacitors between 5V and ground on the power pins of the op-amps?


What type of photography lens minimizes background blur?

I'm in the market for a lens I can use for portrait photography as well as nature. I hate background blur. The portrait photography I do and get a great response from, are the ones where I frame the subject myself.   What type of lens, for a reasonable price, can I get that will not blur the background, yet still provide great quality photos?  At the moment, I own a Nikon Coolpix p510. I plan to buy a camera after I pick out the lens to get the best results. I'm fine with slight blur while the focus is on the main subject, but I have noticed while looking at portrait lenses, most remove background details all together.


How to disable suspend with command line or config file?

I want to disable suspend because my VPS goes into suspend and I cannot access it.  How I can do that?


I'm making a circuit which basically should turn on a led when it's dark and turn it off when there is more light. To test the light I've used a photoresistor, and to turn the led on/off a comparator (an LM339N). Here's my circuit:   My problem is that the led DOESN'T glow and there isn't any voltage/current on the comparator output. Why!? I checked it out, all the inputs works fine, their voltage is not 0.  Well, the generator is actually 10V, but it shouldn't matter I think (even with 5V it didn't work).


Sketchy UI used in Ubuntu documentation?

I'm looking for the software used to create the UI mockups in Ubuntu's documentation, for example, here:   Thanks.      Edit: The replies I got here are a bit off mark. I do agree, though, that my question is a duplicate. I eventually found the answer here:


Finding nth term when recurrence relation is given

$$a_k = \left\{      \begin{array}{lr}        2a_{k-1} - a_{k-2} &: if \space k > 2 \\        3 & :if\space k =2 \\        2 & :if \space k =1      \end{array}    \right.$$  It's easy to see that the nth term is n+1 based on the pattern but how do I actually show it? Is there a general way to solve these recurrence problems?  The only way I can think of is $a_k - a_{k-1}=a_{k-1}-a_{k-2}$ implies arithmetic progression, so based on that n+1


Unable to upload a file using selenium/web driver running with java

I have a complicated interface where uploading a file is three step ( The forum is not allowing me to add screenshots of my window so please try to visualise it) step 1 click on browse tab and select a file to upload( This will create progress bar) step 2 click on start upload button Step 3 click on finish button firebug information about the elements on the page have been pasted at the bottom of the page. Id of my browse button is fileInputUploader  The code I am using to try and upload the file is ( within my test class)  WebElement upload = driver.findElement(By.id("fileInputUploader")); upload.sendKeys("C:/Users/Deepankur/Desktop/Deepankur Folder/selenium Test Cases/test12.jpg");   But it's not doing anything  I am not able to see that upload progress animation in step 2, so I can click on start upload and finish it. Any help will be much appreciated.  Here is the html for this section of my page
  <input width="110" type="file" height="30" id="fileInput" name="fileInput" style="display: none;"><object width="110" height="30" type="application/x-shockwave-flash" data="/core/webcore/swf/uploadify.swf" id="fileInputUploader" style="visibility: visible;"><param name="quality" value="high"><param name="wmode" value="opaque"><param name="allowScriptAccess" value="always"><param name="flashvars" value="uploadifyID=fileInput&amp;pagepath=/core/root/&amp;script=/core/application/pApproval/uploadify.cfm&amp;folder=//192.168.100.51/client_data/CPM_ConcretePlatform_DEV/userUploads&amp;scriptData=project_id%3D19%26client_id%3D2172%26project_file_type%3D2%26file_zone_id%3D104%26file_zone_group_id%3D17%26parent_project_file_id%3D0%26approval_rule_id%3D10%26job_id%3D519%26status_id%3D17&amp;width=110&amp;height=30&amp;wmode=opaque&amp;method=POST&amp;queueSizeLimit=20&amp;simUploadLimit=1&amp;fileDesc=Please see the list of allowed file extensions under More Help Uploading&amp;fileExt=*.jpg;*.tif;*.pdf;*.qxd;*.eps;*.psd;*.zip;*.doc;*.ppt;*.xls;*.pdf;*.mov;*.ai;*.png;*.bmp;*.ait;*.dwg;*.dxf;*.flv;*.indd;*.txt;*.inx;*.gif;*.cad;*.docx;*.xlsx;*.pptx;*.mpp;*.m2v;*.avi;*.vob;*.mpg;*.wmv;*.mp4;*.m4v;*.misc;*.ppsx&amp;multi=true&amp;sizeLimit=26214400&amp;fileDataName=Filedata"></object>

  Start Upload


Novel about a spaceship in a distortion, a galaxy appears around a corpse

Well, I'm asking for help from other SF fans because I'm trying to recover the title of a novel I read years ago... Obviously I don't remember the title or the author. I remember that the plot was about a spaceship that, for some reason, finds itself in a distortion due to which it begins to increase in volume (I think it's something like that). An image that I remember well is that at a certain point, in the central area of said spaceship, where a corpse had been placed, something milky appears and gets bigger. At the beginning the crew thinks it is a ghost but as time goes by they realize that it is a galaxy.


In the video made by the slo-mo guys , at time 1:47 comes a moment when a water droplet(almost completely spherical), is seen to 'float' on the surface of the water for a while.  So why did this case arise? Is it something to do with the tuning fork, or solely a surface-tension based phenomenon? If it is the latter, why does it break back into the whole liquid,and  is there an ambient temperature and pressure for this to occur?


Is this a valid proof for the reverse triangle inequality: Given $x,\,y\in\mathbb{R}^n$, $\|x-y\|\ge |\|x\| - \|y\||$.

$\def\a{{\bf a}} \def\b{{\bf b}}$ $\def\x{{\bf x}}$ $\def\y{{\bf y}}$  I've seen various methods of proving the reverse triangle inequality but I was wondering if this one is fine as well.   Prove the reverse triangle inequality:  Given $\x,\,\y\in\mathbb{R}^n$, $\|\x-\y\|\ge |\|\x\| - \|\y\||$.   $\textbf{Solution}$ Let $\x,\y \in \mathbb{R}^n$. Now, $\x=\x-\y+\y$ and so $||\x|| = ||\x-\y+\y|| \le ||\x-\y|| + ||\y||$ by triangle inequality. Thus, $||\x|| - ||\y|| \le ||\x-\y||$ [*].   Now for $\y$. Again, $\y = \y-\x+\x$ so $||\y|| = ||\y-\x+\x||$ implies $||\y|| \le ||\y-\x|| + ||\x||$ by triangle inequality. So, $||\y|| - ||\x||\le ||\x-\y||$. Hence, $-||\x-\y|| \le ||\x|| - ||\y||$ [**].   By [*] and [**], $-||\x-\y|| \le ||\x|| - ||\y|| < ||\x-\y||$ implying $\bigl ||\x|| - ||\y|| \bigr\rvert \le ||\x-\y||$ for all $\x,\y \in \mathbb{R}^n$.


How many different classifications of people are there in The Handmaid’s Tale?

In the TV series The Handmaid's Tale we see a dystopian future where people live in classes.  I have heard of:   Ant - A worker Eye - Spy/Secret Police Aunt - Keeper of the Handmaidens Commander - Boss of some kind (I don't know if it is political or military) Martha - housekeeper Handmaid - Walking baby machines   Are there any other classifications and what do they mean?


I am using an APEX batch to process and insert large amounts of data. Essentially I would like it to process every row to catch any errors with the data and then rollback the entire batch if a single error is found. Is there any simple way to do this?  I have tried using a Save Point, but because they are not serialisable, it doesn't work across the entire batch.   Just to clarify, by error I mean an error that I have defined, error with validation, etc. Not an Exception thrown by the system.


for triamgle $ABC$ prove that $\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b} <2$

Let   $ a,b,c$ be lengths of sides  triangle $ ABC$.   Prove that:   $\displaystyle \frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b} <2$   $\bf{My\; Try::}$ For a $\triangle $ with sides $a,b,c$  $a+b>c$ and $b+c>a$ and $a+b>c$  Now let $x=a+b-c>0$ and $y=b+c-a>0$ and $z=c+a-b>0$  So $\displaystyle 2a=x+z$ and $2b=x+y$ and $2c=y+z$  So equality convert into $$\frac{x+z}{x+2y+z}+\frac{x+y}{x+y+2z}+\frac{y+z}{2x+y+z}<2$$  How can i solve above inequality, Help required, Thanks


Time to collide of hammer vs Moon, feather vs Moon, considering that the Moon is attracted by them (barycenter)

I am an extreme novice in Physics, I am also a beginner in Physics Stack Exchange, and I'm not fluent in English, so please bear with me, consider my question with indulgence. I request indulgence especially because $99\text{%}$ of my question is a well-known question with an evident and well-known answer, but the important thing of the question is the remaining $1\text{%}$ which I will try to explain the best I can. This well-known question is:  "On the Moon, drop a feather and a hammer, will they touch the ground at the same time?"  (and the question is the same on Earth if we exclude the air density/shapes of bodies that fall). This question is always answered by the strict affirmation that "yes they do", and confirmed by astronaut . I agree with that. I agree that it's a strictly equal time, if we consider that the Moon is not attracted by the feather or the hammer. It may sound obvious to many people that the Moon is not attracted by so much light objects, but theoretically it is because these objects have a mass, even if the feather/hammer mass is around 1E-23 times of the Moon mass. (It's like the Earth which is 100 times more massive than the Moon, so the Earth is also attracted and the effect is its "oscillation" around the  which is at approximately $4,670$ to $6,380\ km$ away from the geographical center of the Earth.) And here comes my question, which may look identical, but there is a change in the conditions and in the enunciation, especially I say "body" instead of "Moon", and I say "mutually attracted" rather than "one object falls on the body" so that you better understand how my question is 1% different from the previous question:  "In space vacuum, a feather and a body are both initially positioned at the same distance and with no relative movement, and are mutually attracted because of their masses and will collide in a given amount of time. Let's repeat the same experiment with a hammer instead of the feather, will they collide in exactly the same amount of time?"  (even if there's a tiny difference of 1E-20 second, I consider that it's not the same time) My assumption is that the hammer and the feather will be both attracted identically by the body, BUT at the same time the body will be more attracted by the hammer than by the feather (because the hammer is heavier than the feather). So, the body and the hammer will collide quicker than the body and the feather. Am I right or not? Where am I wrong? Of course, my question is related to the first well-known question, and my assumption is that there is a difference, although extremely small, maybe 1E-20 seconds, but theoretically it's different because the Moon is attracted. What do you think? Do you know any document which talks about that? (I searched a lot but I couldn't find anything) Thank you very much for your interest in this question.


Why are parallel spins energetically favorable for nucleons?

For deuterium, both the proton and neutron preferentially occupy $1s_{1/2}$ orbitals which have orbital angular momentum $l=0$ and spin $s=1/2$. By coupling their orbital and spin angular momenta for a new conserved quantum value $j$, one gets a spin of $1/2$ for each particle. j-j coupling then leads to either a $I=1$ or $I=0$ total nuclear spin corresponding to symmetric and anti-symmetric spin states respectively. Since the the spatial wavefunctions for the s orbitals are each of even parity, their coupled wavefunctions would be expected to be of even parity as well. So, exchanging each of the nucleons would spatially symmetric. It is theorized that deuterium represents an anti-isymmetric isospin state. Thus the total wavefunction would be anti-symmetric in the spin one state which apparently is the only bound state for deuterium. The total wavefunction being symmetric in the spin 0 state would violate spin-statistics theorem.  It is also known that even-even nuclei have protons that pair with protons and neutrons that pair with neutrons. These pairings involve identical particles and coupling their identical spatial wavefunctions would lead to even parity and hence be spatially symmetric under exchange. Isospin being symmetric, their combined spins would need to be anti-symmetric to avoid violating spin statistics. Which is why these nuclei have total spin $I=0$.  If one were to set aside isospin considerations, the proton and neutron in the deuterium are distinct particles (their masses are not the same), so their angular momentum can be coupled to a spin one or a spin zero state without violating spin-statistics. It appears that the spin one (parallel spins) state is energetically more favorable and in fact is the only bound state, with singlet state unbounded and dissociated. However, with even-even nuclei, the pairings involve identical particles so the energetically more favorable spin one state is blocked by the Pauli exclusion principle.  So my question is there a way to explain without invoking the concept of isospin, why neutron-neutron and proton-proton pairings in even-even nuclei have anti-symmetric spins whereas the deuterium nucleons pair up with symmetric spins.


I evaluated this integarl:     $$\int_{-2}^2\int_{y^2-3}^{5-y^2}dxdy=\boxed{\frac{64}{3}}$$   Now I need to evaluate it with changing the limits,  My attempt:  $$=\int_{-3}^1 \bigg[\int_0^{\sqrt{x+3}}dy\bigg]dx+\int_{1}^5 \bigg[\int_0^{\sqrt{5-x}}dy\bigg]dx$$  $$\int_{-3}^1 \sqrt{x+3}dx+\int_{1}^5 \sqrt{5-x}dx=\boxed{\color{red}{\frac{32}{3}}}$$     Where am I wrong?


I'm trying to delete some duplicated rows of my table. I'm starting by select all the duplicated rows by executing this query :  SELECT a.id as id FROM table A join table B on A.site = B.site  where A.nb_affichages = B.nb_affichages and A.nb_clics = A.nb_clics   Then i try to delete all the selected ids from the first query :  DELETE FROM table WHERE id IN ( SELECT * FROM ( SELECT a.id as id FROM table A join table B on A.site = B.site  where A.nb_affichages = B.nb_affichages and A.nb_clics = A.nb_clics) AS p )   This second query deletes all the rows selected in the first, instead I want to let one row and delete the others.  So anyone can help me to optimize this query.


Today I started having the following issues in Pokémon GO:   I can't spin pokéStops and get rewards When I catch pokémon, even the lowest CP ones, they escape every time. I've tried using razz berries, that doesn't work. Neither does using great balls.   I do have Internet. I'm not on wifi. I can send messages and browse Internet.  NOTE: I did try to modify my gps location and I was unsuccessful. I only got a pokémon or two and deleted them immediately. I do apologize for trying to hack it but I'm now fully legit.


Don't combine Taskbar Icons, but only display Icons

I've never really liked this feature about Win7, but I guess I just got used to it. The feature I don't like is mousing over the Win7 icons when there are multiple windows of the same type open. You have to waste that extra time choosing the window after it pops up and it's just clunky.  The XP taskbar was nice, because you didn't have to go through any of this, but it had the problem where you ran out of taskbar space fast. I often resized my taskbar to take care of this. However, on Windows 7, I don't use up even 1/3 of my taskbar. I have all this space I can use, and instead it's all squished to the left, making me take extra steps.  Are there any applications I can use to get this desired behavior, or else what route would you recommend to take to write this behavior myself? My first thought would be C# and the Windows taskbar APIs.  PS. If it's not clear what I'm asking for, please let me know, I'll try to be more specific.


How do I diagnose the source of focus problem in a camera?

Probably a novice question, but how do I correctly diagnose from a photo for what reason that camera wasn't able to focus properly?  It can be any 1 of the following   Unsteady hand Lens issue Metering Re-Calibration required in camera or ...   Is there a set of unsaid protocols that needs to be followed by a photographer?  Goal is to get a sharp and crisp image prior to editing.  [PS: I own a Nikon D5200.]


I'm thinking about buying a Chromebook and heard that it works good with Ubuntu. My question is, what does ubuntu offer me while using a Chromebook? Does it support Arabic language?


A friend who is learning English asked me this question today and I was unable to give a definitive answer on grammar.  The phrase constructions below are quoted verbatim from them :   An English person generally has a pet  English people generally have a pet   English people generally have pets   Posibilities of tidying up the  phrase construction aside, specifically in terms of the grammar:  My thinking is:   (1) is incorrect, although I am toying with the idea that perhaps (at a push !) with a more specific subject it could be acceptable (e.g. a blind person generally has a guide dog) (2) and (3) are largely interchangeable, but if you were being strict about grammar, (3) would be the correct answer because of the plural subject.   However I would be interested to know what the specific grammar rules are in relation to generic constructs (both for my own interest and that of my friend).


How to remove spikes from switching transistor?

I am building a steady current source which delivers steady current (0-20mA) to an LED. The brightness of the LED (current) is controlled through a potentiometer's voltage and a voltage follower as shown in the picture below. Further, I want to blink (modulate) this LED with a square pulse frequency of 2kHz using a switch between the transistor gate and the voltage follower output.  The problem is that every time the switch closes, spikes are produced at the base and as a result at the source. Even when I reduce the current of the LED to 1mA (example picture 2), the spikes don't go away. Only when I set the current of LED to 0 do the spikes dissapear.   So the question is how can I remove/reduce these spikes? Is there some way?  [


Can I install two independent gfci outlets in one double-gang box?

Cam I have two GFCIs connected to one double gang box in my laundry room and if so can I do a single line connection so that they both can work independently?  I have a 12/2 going from the panel through conduit (copper wire) to the double gang box. I want to have each GFCI to run independently without using the load. Why, in case one shuts off the other isn't affected. the double gang box is standard. the device is a Leviton 20 amps. I was told that you can run 12/2 from the panel to the first GFCI black and white. Then connect the second GFCI using a jumper and attaching it to he second GFCI. Is this acceptable by code. we use a washer,dryer in the laundry and the garage heavy machinery. so why should this be a problem running two independent?


Can I use my UK C-type business visa for a tourism trip?

My visa was issued in October 2015, valid for 2 years. and it is C type Business. Since I received my visa a little later than the proposed meeting dates, I did not travel. Now I intend to travel as a tourist for 9 days. Can I still use that visa?


Are there functions satisfying $\int f(x)g(x)dx=\int f(x)dx \times \int g(x)dx$  I came up with one which is  $f(x)=e^{x \sec ^2 \alpha}$ and $g(x)=e^{x \csc^2 \alpha}$  $$\int f(x)g(x)dx=\frac{e^{x(\sec^2 \alpha+\csc^2 \alpha)}}{\sec^2 \alpha +\csc ^2 \alpha}$$  Also  $$\int e^{x\sec^2 \alpha}dx \times \int e^{x \csc^2 \alpha} dx=\frac{e^{x(\sec^2 \alpha+\csc^2 \alpha)}}{\sec^2 \alpha \csc ^2 \alpha}=\frac{e^{x(\sec^2 \alpha+\csc^2 \alpha)}}{\sec^2 \alpha +\csc ^2 \alpha}$$


Integral of $\int\ e^{-x/2}\sqrt(sin-1)/(cosx+1)$

$\int\ e^{-x/2}\sqrt(sin-1)/(cosx+1)$  The result that I'm getting here contains a cosecx term but the answer has secx term! Please help.


Can an integer of the form $4n+3$ written as a sum of two squares?

Let $u$ be an integer of the form $4n+3$, where $n$ is a positive integer. Can we find integers $a$ and $b$ such that $u = a^2 + b^2$? If not, how to establish this for a fact?


I am looking to make a website and in the future desktop apps as well and i know nothing about db design so what tutorials or books (online preferably) are there? thanks


Estimate error of the steepest descent method

I’m reading A.Zee’s qft book.  He gave an error estimation of the  as above, but I found it difficult to verify it. Indeed, I learned the method from a mathematical physics lecture years ago but never heard about its error estimation. Any help?


Mirror modifier on a curve doesn't work as excpected

I would like to make a two wires wound on themselves like for light garland (like a spiral).  To make it easier i use a curve (i will later add bevel and array modifier). But I have a problem with mirror modifier, this modifier is very useful to create directly the second wire.  This is the expected result :  I only succeeded to make the wire mirror around the plan y=0 and not the axis y. I got :  I have also tried to mirror around a straight curve.


Say we are given a conveyor belt with sand falling onto it at rate $\Omega$. I am trying to find the power it takes for the belt to operate if it goes forward with constant velocity $v$, but using two different approaches I get two different answers.  The first way, I say that in one second, $\Omega$ amount of sand falls onto the belt, thus every second $\frac 1 2 \Omega v^2$ is required to continue moving the belt forward (simply by looking at kinetic energy difference) and $P=\frac 1 2 \Omega v^2$  The second way, I saw that $F=\frac {d(mv)} {dt}$, thus $F=\Omega v$. Finally, $P=Fv$ so $P=\Omega v^2$.  So which one is it: $P=\Omega v^2$ or $P=\frac {1} {2} \Omega v^2$, and where did I make an incorrect assumption in my two methods?


AMD64 Assembly Language Compile/Build ERROR

I am trying to learn assembly language and am trying to do a basic "Hello, World" output. The error I am getting is:  ld: warning: -arch not specified ld: warning: -macosx_version_min not specified, assuming 10.10 ld: warning: ignoring file hw.o, file was built for unsupported file format  ( 0x7F 0x45 0x4C 0x46 0x02 0x01 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 )  which is not the architecture being linked (x86_64): hw.o Undefined symbols for architecture x86_64:   "start", referenced from:     implicit entry/start for main executable ld: symbol(s) not found for inferred architecture x86_64   My .asm file:  1 section .data msg db "hello, assembly!"  section .text global _start _start:    mov rax, 1      ; rax: temp register; when we call syscall, rax must contain syscall number                    ; 1 means that we will use sys_write system call    mov rdi, 1      ; rdi: used to pass 1st argument to function                    ; it will be the first argument of sys_write    mov rsi, msg    ; rsi: pointer used to pass 2nd argument to functions                    ; msg will be second buf argument for sys_write    mov rdx, 13     ; rdx: used to pass 3rd argument to function                    ; third paramater, length of the string. 3rd argument of sys_write    syscall         ; we have all arguments now we call sys_write with syscall    mov rax, 60     ; pass 60 to rax for syscall exit    mov rdi, 0      ; error code, so with 0 are program must exit succesfully    syscall         ; execute exit code   What I am entering in the command prompt:  $ nasm -f elf64 -g -F dwarf hw.asm $ ld *.o   After I execute the second line on the command prompt, I get the error above.


Determinant of a n x n Matrix - Main Diagonal = 2, Sub- & Super-Diagonal = 1

I'm stuck with this one - Any tips?  The Problem:     Let $n \in \mathbb{N}.$ The following $n \times n$ matrix:      $$A =  \left( \begin{array}{ccc} 2 & 1 &  &  &  & ...\\ 1 & 2 & 1 &  &  & ...\\  & 1 & 2 & 1 &  & ...\\  &  & 1 & 2 & 1 & ...\\  &  &  & 1 & ... & 1\\ ... & ... & ... & ... & 1 &2 \end{array} \right) $$      e.g. for the main diagonal = 2, the sub- and superdiagonal = 1 .       Show with Induction that $\det(A) = n + 1$.      My solution approach: Laplace Expansion starting with the 2 in the bottom right corner $(a_{n+1,n+1})$. But how can I tell wether its positive or negative? After that I'm stuck with the 1 $(a_{n,n+1})$(the sub matrix matrix becomes ugly and I get a recursively solution). How can I formalize this in a proper manner?


Applied for a visa to visit my uncle in the UK but was refused giving the following reasons:  They said I applied to to visit my aunt (which I never stated in my application) but brought supporting documents from my uncle stating his willingness to bear the cost of my trip, meaning there's no personal or professional relation between us (actually when filling the form there was a question that went like what's the relation of the person in the UK to you but there wasn't uncle in the options provided so I chose other relative and added his contact details and address so I don't know where the aunt came from, does choosing other relative mean aunt or something?)  Secondly they said I stated in my application I'm a non working student and that I attached a bank statement with a closing balance of over 200GBP and that they aren't satisfied with the evidence of the source or the money is for my exclusive use (I don't really get this point, are non working students required to have a specific amount before applying or what?)  Lastly they said I said the cost of the trip to me personally was 300GBP but I had less than that in my account so I can't sustain myself in the UK does it not contradict the second reason?) they also said I stated I had 300USD for the trip but the cost of flight was 285USD and my living expenses 200USD meaning I'm short of 185 (I thought they just needed an information about these so provided them because my uncle was bearing the cost of my trip so attached all the necessary documents to the invite not knowing they calculated using the money my account, how was I supposed to answer the questions under income in expenditure in the case where my sponsor that's my uncle was bearing all the cost of my trip? Can I apply again? And how many times can I apply after refusal?


Should I delete an answer that hasn't received any upvotes?

Should I delete one of my answers that hasn't received any upvotes, even if it's a good answer?


Stuck on rejection region for Likelihood ratio test

Assume $X_1$ .. $X_n$ ~ iid beta($\theta$,1)   I'm supposed to construct a Maximum likelihood ratio test for:  $H_0$: $\theta$ = $\theta_0$  $H_1$: $\theta$ != $\theta_0$   But I'm stuck at the last step of simplifying the rejection region.  My steps are as follows:  1) Obtain the MLE (skipping derivation)  $$\theta_{mle} =  \frac{-n}{\sum_{i=1}^n log(x_i)}$$  2) Likelihood ratio:  $$ \frac{\prod_{i=1}^n  \frac{\Gamma(\theta_0+1)}{\Gamma(\theta_0)\Gamma(1)} x_i^{\theta_0-1} (1-x_i)^{1-1}}{\prod_{i=1}^n\frac{\Gamma(\theta_{mle}+1)}{\Gamma(\theta_{mle})\Gamma(1)}x_i^{\theta_{mle}-1} (1-x_i)^{1-1}}$$  Simplify the gamma terms and Cancel the last term:  $$ \frac{\theta_0\prod_{i=1}^n  x_i^{\theta_0-1}}{\theta_{mle}\prod_{i=1}^nx_i^{\theta_{mle}-1}}$$  Combine the product terms:  $$ \frac{\theta_0}{\theta_{mle}}\prod_{i=1}^n{x_i^{\theta_0 - \theta_{mle}}} $$  Rejection Region:  $$ P (\frac{\theta_0}{\theta_{mle}}\prod_{i=1}^n{x_i^{\theta_0 - \theta_{mle}}} < K) $$  And now I'm stuck. I know i must get to something like   $$ P (\bar{x} < c) $$  But I'm unsure how to proceed. Any help will really be appreciated!!


There are $n$ bins of which the $k$th contains $k-1$ blue and $n-k$ red balls.You pick a bin at random and remove two balls at random without replacement. Find the probability that: a) the second ball is red b) the second ball is red, given that the first is red.


minimal polynomial of nth root of 2 over $\mathbb Q$

The minimal polynomial of nth root of unity is the cyclotomic polynomial. What is the minimal polynomial of nth root of 2? Is it related to the cyclotomic polynomial?


This class compiles just fine:  public class Student{ //define variables static String name;  //define constructor public Student(String n){     name = n; }  //define method to display name public static void displayStudent(){     System.out.println("Name: " + name); } }   Here is the class where I am trying to call the displayStudent() method, but I am getting java.lang.NullPointerException exception coming from the for loop :  public class MyClass{  //define array of object Student private Student[] students;  //constructor MyClass(int size){ Student[] students = new Student[size]; }      //define method to display the students variable public void displayAllStudents(){     for (int i = 0; i <= students.length; i++){         students[i].displayStudent();     } }   I am trying to fixing it with Eclipse, but it says that in MyClass "the value of the local variable students is not used". Where is my mistake?


How to execute a program periodically? & disply difeerence in output

I want to run command repeatedly and display their output.  Example:   I want to run ls command repeatedly and display output so-that I can see changes in directory contents.  Also facility to highlight difference in out-put and specify time-interval.  How to do that? suggest command.


operator factoring partial differential equations

I have a partial differential equation :   $u_{xx}-3u_{xt}-4u_{tt}=0$ with initial and boundary conditions: $u(x,0)=x^2$, $u_t(x,0)=e^x$.  We need to find $u(x,t)$.  The hint is : Factor the operator as was done with the wave equation $u_{tt}= c^2u_{xx}$.    Here is my thought process.  Operator factoring is exactly like factoring from elementary school algebra.  So I can pretend for a moment that   $u_{xx}-3u_{xt}-4u_{tt}=>(x^2-3xt-4t^2)=(x-4)(x+1) $  So   $u_{xx}-3u_{xt}-4u_{tt}= (\partial_x -4\partial_t)(\partial_x+\partial_t)u=0$  So the last step above is using the suggested hint of operator factoring.   From the general solution of wave equations we know it will have the form:   $u(x,t)=f(something1) + g(something2)$  Using the factored term: $(\partial_x -4\partial_t)$ we know that $something1 = x-4t$.  Using the factored term $(\partial_x+\partial_t)$ we know that $something2 = x + t$.   Therefore the solution is:   $u(x,t)=f(x-4t) + g(x+t)$  Then I use the initial and boundary conditions giving me:   $u(x,0)=f(x)+g(x)=x^2$ $u_t(x,0)=g'(x)-4f'(x)=e^x$  However, I am unable to get the correct answer from here:   $\frac{4}{5} (e^{x+t/4}-e^{x-t}) + x^2+\frac{1}{4}t^2$


My phone storage is empty when connected to pc

I need to back up all data and media on my phone but every time i connect it to pc everything is fine and my pc recongize the phone but not every time i need to plug and unplug phone several times to make pc recognize it .what ever when i open my phone storage it say folder is empty iam sure that using MTP not PTP my phone storage working on all computers except mine and all phones storages appear on my pc except my phone i have checked drivers and all working properaly . any help ?


How can I tell hotels exist that aren't on the booking web sites?

There are a ton of sites out there to help book hotel rooms and to aggregate all the different sites to book hotel rooms. These companies make enough money to buy ads on TV, so I won't name them here. I normally poke around 3 or 4 of these as part of planning any trip.  I am now starting some very long term planning for a 6 week South Pacific trip, which includes undertstanding what hotels costs on some very small islands. I have paper guidebooks and I've been looking online. But I come across anomalies. For example, a place which has only 9 hotels listed on the sites I use, and prices range from $1000/night down to $200/night, then when I read the reviews on that cheapest one people are saying "it's nothing special, there are 5 or 6 places just like it here for half the price". Well, not on this site there aren't!  My guess is that many of these places don't have web sites, or don't have online booking, and therefore aren't getting into the aggregators. For some islands I have found local tourism boards with lists of "pensions" and such, typically cheaper than what I can find on the aggregators.    But how can I know? I don't want to assume that popular web sites represent reality, and choose only from places listed there. But I don't want to invest 10-20 hours of research per island only to discover the aggregators had everything. How can I know where the coverage is good and where it isn't, what kinds of hotels are more or less likely to be listed at expedia, trivago, booking, hotels, tripadvisor, and the like? (For example, I don't want to stay at a hostel, so I don't mind if they're not included in online sites.) Are there sites like wikitravel that list places without much of an internet presence?  I'm starting my research over a year before the trip, but wading through hotel pages is not the fun part of the planning so tell me how the smart people do it.


Alternative shells (Javascript, Ruby, etc)?

Does anyone use a shell written in Javascript, Ruby, Clojure, etc as their everyday unix shell, instead of bash, zsh, etc? Is there any reason not to?


Why are effective pixels greater than the actual resolution?

compares Canon EOS 550D and Canon EOS 500D cameras and mentions     18.7 million effective pixels   for 550D. However the best resolution possible using this camera is  5184 * 3456 = 17915904 ~ 17.9 million pixels   What are effective pixels, and why is that number greater than 17.9 million in this case?


create entity with entity_metadata_wrapper and set Date value

I want to create a node entity. This node contain a date field. So, how can I set the date value ? (using entity_metadata_wrapper)  After several google search and code try, I don't find the solution.. My last try :   $date_temp = new DateTime(date('2013-12-01 00:00:00')); $new_devicew->field_top[0]->field_date->set($date_temp->getTimestamp());   But i get this error :   EntityMetadataWrapperException : Unable to set the data property field_date as the parent data structure is not set. in EntityStructureWrapper->setProperty()


how do i get the dream suite in acnl 2019

i have been playing since 2015 and i'm still playing today, it is currently 2019 and i now just realized that there is more to do in this game,i have literally tried going back in time (in the game)and looked in the town hall to see if Isabelle was sleeping but she wasn't ,can someone help me get the dream suite when its 2019?!!


I couldn't connect to Windows Update nor install .NET so I've done a clean install of Windows 8.1 from Microsoft's iso.  The same problem occurs : the loading bar is never beginning ! No error message.  I've compared what is happening on my Win 7 netbook with Wireshark. When searching for updates, it's sending http requests to Microsoft with a URL like /v11/2/microsoftupdate/. The fresh install of Win 8.1 basically doesn't try to connect anywhere.  I have no proxy, no firewall, no special configuration. Both laptops are on the same network.


How does a JavaScript function store local variables after being called?

I came upon this simplified example of a memoization function in JavaScript. It's then used to memoize a function that adds 2 to whatever number is passed in. When I saw this, it didn't seem obvious that the memoize function would continue to store the cache variable after being ran since it's not a property of memoize, just (seemingly) an ordinary local variable. Shouldn't it be overridden whenever memoize is called via plusTwo? Where can I find out more about this behavior in JavaScript?  var memoize = function(function_) {     var cache = {};      return function() { // What does this function do?          //makes a string out of the arguments of the function that was passed in         var arg_str = JSON.stringify(arguments);          /*          sets the cache value for the arguments to the value that was already calculated          (if available) or calculates the value for the passed in function on its         */         cache[arg_str] = cache[arg_str] || function_.apply(function_, arguments);          console.log(cache);         // returns the calculated (or cached) value         return cache[arg_str];     }; };  var plusTwo = memoize(function (x) {     return x + 2; });  module.exports = memoize, plusTwo;


mod_rewrite redirect any domain except principal domain to the principal domain

I have some rules as follows:  RewriteCond %{HTTP_HOST} ^domain.com RewriteRule ^(.*)$ http://www.domain.com/$1 [R=permanent,L]   I would like to make the rewrite condition match ANY domain OTHER than the domain www.domain.com . How can I do this without explicitly make a RewriteCond for each case?


From APUE     There are  rules for who can change the IDs. Let’s consider only the   user ID for now. (Everything we describe for the user ID also applies   to the group ID.)         If the process has superuser privileges, the setuid function sets the real user ID, effective user ID, and saved set-user-ID to uid.   If the process does not have superuser privileges, but uid equals either the real user ID or the saved set-user-ID, setuid sets only the   effective user ID to uid. The real user ID and the saved set-user-ID   are not changed.   If neither  of  these  two  conditions  is  true, errno is  set  to EPERM and -1 is returned.      What does it mean by "a process have or does not have superuser privileges"?  Is it defined as whether the real user ID of the process is root or not?


Calculating the asymptotes of an hyperbola from the general equation

Suppose that the conditions which ensure that the following equation is an hyperbola are verified:  $$ax^2+2bxy+cy^2+2dx+2ey+f=0$$  What are the general expressions of the two asymptotes of the hyperbola?    EDIT  I tried to follow the procedure , but I get (I assumed all the coefficient greater than zero; if I did not give a sign to the coefficients, I cannot solve the limit):  $$\lim_{x \rightarrow + \infty} y(x) - mx = $$  $$ = \lim_{x \rightarrow + \infty} \frac{-E- Cx + \sqrt{(E + Cx)^2 - 4B(Dx + F)}}{2B} - \frac{2A}{C}x = - \infty$$  Thank you for your help.


Single point vs Ground plane, in audio OP AMP PCB layouts

Recently I had posted a seemingly innocent question on another forum. I was trying to keep a small and relatively simple circuit down to a 2 layer board and was asking about the shielding merits of a copper pour tied to analog ground, as opposed to dedicating unbroken separate plane used for ground. Though my question was only in reference to the shielding value of such a copper pour, a major controversy started on an entirely different point. In my layout I had created a virtual ground using the typical voltage divider feeding a unity gain configured OP amp, and then had run every single analog ground return to a point adjacent to the output of that virtual ground. I had also done a copper pour on the least busy layer and tied it to that same analog ground, again at that same single point. But there soon ensued a series of posts lambasting my use of such a convoluted "spider web" scheme, with many chiming in that I should just create a ground plane and just make all connections to the nearest available point of that plane ( through  via when necessary). Well doing so certainly makes for a cleaner and simpler layout visually. But having gone the "single point" route for so many years, and having mostly successful (meaning quite and stable) designs, I'm hesitant to change. Especially as some of the arguments spoke of single point grounds as something archaic, and relegated to vacuum tube circuits. What?   So anyway, just poking around, my research on the subject seemed to show two camps on this subject. One argument is that when an unbroken ground plane is available, it is always superior. The other argument says that if its a high frequency circuit a ground plane is better, but for a low frequency circuit (including audio), the single point ground method is better, mostly to avoid ground loops.  Of course I still have a dilemma, as prototype costs are constraining me to a 2 layer board if possible this time, and this means that my pseudo ground plane will, at best, be a copper pour, broken by some short traces here and there. But before adding that complexity or possible exception to the rule, I'd like to put this specific question out for general discussion: For an audio design involving OP Amps, when is a Single point" ground scheme the bast way to go, and when is just the simpler "nearest path to a ground plane" the better (or at least an adequate) choice.   By way of example, these two layered screen shots show two reasonably similar versions of the same board, which in reality is about 4" x 2.5". In the first you can see lots of long traces on both sides of the board culminating at a single pad labeled AGND. The second is nearly the same circuit, but this time the blue copper poor area is part of the analog ground net, so all those long traces have gone away in favor of the nearest path to the ground plane/ copper pour. Aside from all possible critique about other layout issues one might see, this is just an example. I'd really like to confine this discussion to the original question.   single point ground version   Nearest path to ground plane version


I am hoping those with more experience in number theory than me can help me out on this question.  After learning that $\gcd(a^m - 1, a^n - 1) = a^{\gcd(m, n)} - 1$, I questioned what is $\gcd(a^m + 1, a^n + 1)$ ($m$ not equal to $n$).  I assumed WLOG that $m > n$ and then used the Euclidean Algorithm to get $\gcd(a^m + 1, a^n + 1) = \gcd(a^{m-n} - 1, a^n + 1)$. However, I am now stuck.  Please explain if the parity of $x$ and $y$ matter.  QUESTION: Calculate $\gcd(a^x + 1, a^y + 1)$


Booting from a USB drive that was originally a boot drive

When Win 7 went RTM, I upgraded my laptop from XP.  But to protect myself against the possibility of having data inaccessible, I got a new disk and put it in the laptop, and took the old (XP) disk and put it in a USB enclosure.  I have no trouble accessing the data on the USB drive under Windows 7.  But I would like to be able to plug it in, tell the BIOS to boot from the USB drive, and be back on my old machine.  The laptop is a Dell Precision M90, and it has a boot from USB option in its boot menu.  But when I try to do that, it does read the drive, gets as far as putting up the Windows XP splash screen and starting the boot progress bar, and then reboots.  What do I need to do to the old disk now running on USB to allow the machine to boot from it?


Why Linux has "bridge" link type, and not a "switch"

In Linux, we can have a virtual bridge device. It is used i.e. by Docker, which creates a default "docker0" bridge. Since in networking bridge is a similar device to a switch (and switch is actually superior and used nowadays instead of bridges), I wonder, why is the link type called "bridge", and not "switch"?


Showing any metric space is a Hausdorff space

This is the question i've been given along with the solution i have written, however, could someone explain why showing $z \notin V$ shows any metric space is a Hausdorff space


When should edits removing clarifying links be reverted

An SE employee has removed a link that added clarity to an answer. This is presumably in response a new . It seems the SE policy, at least if applied to links that add clarity) is at odds with the goals of the community to provide clear and concise answers.  Should we be rolling back all edits that remove links that provide additional clarity to a question/answer? If SE disagrees, then they can lock the posts while the content dispute is settled. They could also issue a warning/suspension, although I am not sure what policy we would be violating for making a post clearer.  [Note that this question pertains to the debacle caused by the alleged slandering of a former moderator by SE (aka what SE in victim blaming refers to as Monica's situation) and therefore if they obey their legal guidance should not be answering.]


Ubuntu 16.04 Jan 3 2018 update causing screen/access issues

Yesterday (Jan. 3, 2018), I installed an OS update (Ubuntu 16.04), using the Software Center. My system isn't working correctly now. When my mouse rolls over the Launch bar, it disappears, then any open window disappears, leaving me with only the desktop screensaver showing. I can't even shut the computer off using the settings button on the top.  I went into the Terminal and attempted to fix it using the following commands:  sudo apt-get dist-upgrade sudo apt-get autoremove   But I'm still having the same problem.  I have reinstalled Ubuntu 16.04 and when I accepted the update on install had the same problem.  I have reinstalled it a second time but have not done an OS update and everything seems to be working fine.    Found another user with the same problem:    Is it possible that the Meltdown security update is at fault?  I've read the update has been issued for 64-bit x86 architecture ();  I'm running a 32 bit i386 architecture.  Could that be an issue and is there a way to correct it?


I have a US transit visa. I am travelling from India to Jamaica. Will I need a UK transit visa as well? My flight goes from Mumbai to LHR to Miami to Montego bay.


I have this old power adapter with a rating of 6V 2.4 Amp. I used a voltage divider circuit made of two 1000 ohm and one 10000 ohm resistors. when i measured the voltage across the 10k resistance, I got an exact drop of 1 volt, i.e., it was reading 5 V. i connected the ends to the micro USB and connected to my windows phone.  The phone was not charging. When i read the voltage with charger, the voltage was only 2.5 V instead of 5 V. What just happened here? the adapter was a 6 V adapter that was used for a router, why did stepping down voltage result in drop in voltage on connecting load. thanks for helping me out. How would i get a 5V to charge my cell phone from this adapter?


Java install does not work - no such file or directory

I am unable to run java after downloading it. I'd appreciate troubleshooting help.     Info: ⠀Ubuntu 14.04 LTS ⠀Acer Aspire V5 with AMD A4 processor ⠀Used Oracle 64-bit Linux version ⠀jdk-8u45-linux-i586.tar.gz    $ java -version bash: /usr/bin/java: No such file or directory  $ update-alternatives --display java java - auto mode   link currently points to /usr/lib/jvm/jdk1.8.0_45/bin/java /usr/lib/jvm/jdk1.8.0_45/bin/java - priority 2 Current 'best' version is '/usr/lib/jvm/jdk1.8.0_45/bin/java'.   The file is there, and it appears to have correct permissions:   $ ls -l /usr/lib/jvm/jdk1.8.0_45/bin/java -rwxr-xr-x 1 root root 5730 Apr 10 10:53 /usr/lib/jvm/jdk1.8.0_45/bin/java


How do I remove the file suffix and path portion from a path string in Bash?

Given a string file path such as /foo/fizzbuzz.bar, how would I use bash to extract just the fizzbuzz portion of said string?


Find the value of $\sin\frac{\pi}{7}\sin\frac{2\pi}{7}\sin\frac{3\pi}{7}\sin\frac{\pi}{14}\sin\frac{3\pi}{14}\sin\frac{5\pi}{14}$

Find the value of $$\sin\frac{\pi}{7}\sin\frac{2\pi}{7}\sin\frac{3\pi}{7}\sin\frac{\pi}{14}\sin\frac{3\pi}{14}\sin\frac{5\pi}{14}$$   $$\sin\frac{\pi}{7}\sin\frac{2\pi}{7}\sin\frac{3\pi}{7}\sin\frac{\pi}{14}\sin\frac{3\pi}{14}\sin\frac{5\pi}{14}$$ $$=\sin\frac{2\pi}{14}\sin\frac{4\pi}{14}\sin\frac{6\pi}{14}\sin\frac{\pi}{14}\sin\frac{3\pi}{14}\sin\frac{5\pi}{14}$$ $$=\sin\frac{\pi}{14}\sin\frac{2\pi}{14}\sin\frac{3\pi}{14}\sin\frac{4\pi}{14}\sin\frac{5\pi}{14}\sin\frac{6\pi}{14}$$  How can I compute $$\prod\limits_{r=1}^{n}\sin\frac{r\pi}{c}$$


No "Altruist" badge awarding notification in achievements popup

Today I , but I've not been notified about it and I don't see it in Achievements popup:


Are there any ways to evaluate $\int^\infty_0\frac{\sin x}{x}dx$ without using double integral?   I can't find any this kind of solution. Can anyone please help me? Thank you.