Can you help me with this?     Let $S^2 := \{x\in \mathbb R^3:||x||_2 = 1\} \subset (\mathbb R^3, ||\cdot||_2)$  and $T:S^2 \to (\mathbb R, |\cdot|)$ be a continuous map.   a) Why does T assume its maximum ($T_{max}$) and its minimum ($T_{min}$)?   b) Is there a point $x_0 \in S^2$ with $T(x_0) = T(-x_0)$?   c) Is there a value $T\in]T_{min},T_{max}[$ that is assumed at only one $x\in S^2$?     a) is easy, it is compact since it's closed and bounded (Heine-Borel).  For b) I know it can't be injective since it maps from a higher to a lower dimension, but I don't know if I can use that to show what I need.  For c) I assume I can use non-injectivity again, but don't know either how. Any hints?


Why does it says "welcome back -user- click here to 'refresh page'"

After logging into one Stack Exchange site, when I visit another SE site, it says to me, welcome back - user - click here to refresh - web page.   Isn't it possible to refresh the page using code & without the user's interaction?


Gimp produces black screenshot after upgrade to Ubuntu 17.10

After I upgraded to Ubuntu 17.10, I am facing a serious shortcoming in gimp. The screenshots are completely black.   Most likely this is a bug, but I thought of investigating a bit just to find out if I am missing something.  The other Screenshot software, version 3.25.0 is working fine.


Compare means of group with a mean of a subgroup

It is possible to compare a variable, for example age, between an entire group of patients and a subgroup of patients (a part of the entire group)?


The following bash script is expected to echo the current ip of the wan, instead of google "what is my ip". Error:     ./ipChange.txt: line 2: +short: command not found   “??   #!/bin/bash ip=dig +short myip.opendns.com @resolver1.opendns.com echo “$ip”   Any idea how to fix it? Thx


Given two vertices and incenter find third vertex

$u=(3,1)$, $v=(3,6)$, $i=(2,3)$, need find $w\in \mathbb{R}^2$ such that $i$ is the incenter of the triangle $[u,v,w]$.  I have looked at some other people's approaches to this problem, but I think those approaches are too complicated, and are more like for some advanced intuitive geometer. With the fact that I'm just taking a course in geometry, my approach is probably not so elegant, but it should work. The problem is that I'm still not getting the correct answer.        Let $\alpha, \beta, \gamma$ be the three angles of $[u,v,w]$. Then bisect the three angles to assume $\alpha/2, \beta/2, \gamma/2$.   We can find that $a=(3,3)$ is the point closest to $i$ on the edge $[u,v]$.   We can now set up the following equations:         $$\alpha/2 = \arccos\left(\frac{(v-u)\cdot (v-a)}{\|v-u\|\|v-a\|}\right)=\arccos\left(\frac3{\sqrt{10}}\right)\implies \alpha = 2\arccos\left(\frac3{\sqrt{10}}\right)$$      $$\gamma/2 = \arccos\left(\frac{(v-w)\cdot (w-u)}{\|v-w\|\|w-u\|}\right)=\arccos\left(-\frac{9}{10}\right)\implies \gamma = 2\arccos\left(-\frac9{10}\right)$$   $$\beta = \pi-\alpha-\beta$$      $$ \cos\alpha =  \frac{(v-u)\cdot (w-u)}{\|v-u\|\|w-u\|} $$   Can someone please suggest what is wrong with my approach? Is there an additional equation missing? Also, I'm getting some "crazy" expression for $\beta$, which even WolframAlpha finds difficult to deal with. Is this geometric problem really that complicated?


Java NullPointerException but String is not empty

I'm currently working on a class which writes Values into CmsXmlContent and saves them as a file. I've got many variables and it's working very well but one String seems to hate me... It returns a NullPointerException everytime.  I tried to wrote it but seriously I'm checking if the String is null AND printing it out with perfect results just a line above.  So hopefully you can help me out :)  Expose:  public class Expose {     private String address, bid, build, corridorNumber, corridorPiece, county,         floor, form, houseType, mark, number, partner, price, registry,         roofAngle, size, status, title, view, width;     private List<String> features, infra, location, media, region, use,         useType;     private List<byte[]> documents, images;     private List<ExposeAbsatz> paragraphs;      // getters and setters }   ExposeAbsatz:  public class ExposeAbsatz {     private String content, headline;     private byte[] image;      // getters and setters }   My Code:  Locale de = Locale.GERMAN; CmsXmlContent xmlContent = CmsXmlContentFactory.createDocument(cms,         de, "UTF-8", CmsXmlContentDefinition.getContentDefinitionForType(cms, "expose")); if (StringUtils.isNotEmpty(thisExpose.getTitle()))     xmlContent.getValue("/titel", de).setStringValue(cms,             StringUtils.stripToEmpty(thisExpose.getTitle())); // works if (StringUtils.isNotEmpty(thisExpose.getNumber()))     xmlContent.getValue("/properties/number", de).setStringValue(                     cms, StringUtils.stripToEmpty(thisExpose.getNumber())); // works as well if (thisExpose.getParagraphs() != null) {     int i = 0;     for (ExposeAbsatz currentExposeAbsatz : thisExpose.getParagraphs()) {     String headline = StringUtils.stripToEmpty(currentExposeAbsatz.getHeadline());         if (StringUtils.isNotEmpty(headline)) {             System.out.println("headline[" + i + "] = " + headline);             // headline[0] = aasd             // absatz is minOccurs="4" maxOccurs="5"             xmlContent.getValue("/absatz[" + i + "]/ueberschrift", de)                                 .setStringValue(cms, headline); // NullPointerException             (...)         }         (...)         i++;     } }


How to delete a content in a view with view rules?

I got two views that displayed two different type of contents. Content A got a field "Title" and content B got the same field. I want to find and delete any number of content of type B that got the same title of a content A. I try to do this with view rules module with some view loops. I found some content B that got a title equal to a title of content. How to delete them?


Image for a submit button - which way is best?

In order to use an image as a form's submit button, I have come across two ways and would like to know which one is correct/best-practice.  Version 1:  <button type="submit">   <img src="mybutton.jpg" alt="Submit" /> </button>   Version 2:  <input type="image" src="mybutton.jpg" border="0" alt="Submit" />   I personally feel that the first version is better because it makes semantic sense and has a type of "submit". In the second version its saying the input is of type "image" which doesn't mean much to me as a human.  Which one should I go with?


What does $_, and $0 represent in sourced bash?

I am having troubles understanding variables {_,0} in the following example.  In script tmp.sh:  func()  { echo $_ echo $0 echo $1 }   calling tmp.sh with parameter x:  ~$ ./tmp.sh x ./tmp.sh ./tmp.sh x   and sourced tmp.sh with parameter x:  ~$ . ./tmp.sh x x bash x   As I understand $_ and $0, the later is for the first argument as in first example it's ./tmp.sh. Why it's equivalent to bash in the second example?  What does . expand to, and the former, which I am not sure about, return last parameter with sourced bash, and equivalent to $0 in unsourced bash. Is that the case?


Prove that every graph in which each vertex has degree at least 2 must contain a cycle. Graph has a finite number of vertices  I need some clarification, I understand that a vertex with degree 2 means having 2 neighbors. So this means that every vertex has two neighbors does this mean that the shape is a triangle with 3 vertices and 3 edges all connected or a square where each vertex is connected to two other vertices. Since they are connect it forms a cycle. However Im having trouble proving it, how will I go about proving this? Thanks in advance


Does it matters where you put the square brackets when creating an Array

Like int [] i or int i [] is there any difference I'm curious


MATLAB showing 0.82-0.80 not equal to 0.02 and similar error in inverting a matrix

I've written the following code*:  function val = newton_backward_difference_interpolation(x,y,z) % sample input : newton_backward_difference_interpolation([0.70 0.72 0.74 0.76 0.78 0.80 0.82 0.84 086 0.88],[0.8423 0.8771 0.9131 0.9505 0.9893 1.0296 1.0717 1.1156 1.1616 1.2097],0.71) % sample output: % X-Input must be equidistant %   -1.1102e-16 n=numel(x);% number of elements in x (which is also equal to number of elements in y) h=x(2)-x(1);% the constant difference %error=1e-5;% the computer error in calculating the differences [It was workaround where I took abs(h-h1)>=error] if n>=3% if total elements are more than 3, then we check if they are equidistant     for i=3:n         h1=x(i)-x(i-1);         if (h1~=h)             disp('X-Input must be equidistant');             disp(h1-h);             return;         end     end end ...   I also wrote a function for calculating inverse of a matrix** where this:  a=[3 2 -5;1 -3 2;5 -1 4];disp(a^(-1)-inverse(a));   displays this:    1.0e-16 *           0   -0.2082    0.2776          0    0.5551         0          0    0.2776         0    Why is there a small difference of 1e-16 occuring? Am I right in saying that this is because computer calculations (especially divisions are not exact)? Even if they are inexact, why does a^(-1) provide more accurate/exact solution (Sorry If this question is not programming related in your view.) Can this be avoided/removed? How?   *for newton backward difference interpolation: (whole code at ), the expected output is 0.85953 or something near that. **using Gauss-Jordan Elimination: (whole code at )


After installing OS 10.9.2 on my computer I can no longer use LaTeX. Every time I try to typeset a document I get an error message:  The program 'pdftex' was not found. Searched in directories: /usr/bin, /bin, /usr/sbin, /sbin, /usr/local/bin.  Check configuration of the pdfTex tool and path settings in the Preferences dialog.   I have seen an answer to this question. The problem is it involves going into the guts of LaTeX. Alas, while I love LaTeX I'm not tech savvy. Therefore I'm more than a little worried about tinkering with the program and losing access to many valuable documents.   Can someone provide a step by step answer for solving this problem. The current answer says to go to:  Library/TeX/Distributions/.DefaultTeX/Contents/Programs/texbin /usr/texbin   I have easily found the Library/Tex/Distributions folder. There are 7 files within it... What do I do next.   Thanks in advance.


How do I use Proportional Edit Correctly?

I've tried everything to fix this. Restarting my computer, closing Blender and opening it again, uninstalling Blender and installing it again. Unless it's a bug, I don't know how to fix this. Advice anyone?  Also here's a screenshot of the issue I'm having.:   I made the mountain after selecting "Spherical Falloff", I'm trying to make a hill, and it's obvious that is no hill.


Proving that $ \langle x,2 \rangle$ is a maximal ideal of $\mathbb Z[x]$

The question asked  mentions:  When the polynomial ring Z[x] is quotiented by the ideal (2,x) we get a field as $\mathbb{Z}[x]/(x,2) \cong \mathbb Z/(2) \cong \mathbb{Z}_2$ which is a field.  I am not being able to flesh out my answer and connect the dots. I know that $\frac{\mathbb Z[x]}{\langle x,2 \rangle }= \frac{\frac{\mathbb Z[x]}{\langle x \rangle }}{\frac{\langle 2,x \rangle}{\langle x \rangle}}$. From here, I can individually show that: $\frac{\mathbb Z[x]}{\langle x \rangle} \cong \mathbb Z,$ and that, $\frac{\langle 2,x \rangle}{\langle x \rangle} \cong \langle 2 \rangle.$ How do I conclude that, $\frac{\frac{\mathbb Z[x]}{\langle x \rangle}}{\frac{\langle 2,x \rangle}{\langle x \rangle}}  \cong  \mathbb Z_{2}$? It seems like I am trying to prove something in this format: $\frac{I}{J} \cong \frac{K}{H}$ because $I \cong K$ and $J \cong H.$ (I believe, this basic concept is essentially what my doubt is) Am I thinking about this the wrong way?


We say charge is discrete because it always has the form $q = n e$, where $n \in \mathbb Z$.   Similarly, I can say that $m = n N_a \mu$, where $n$ is number of moles, $N_a$ is avogadro's constant and $\mu$ is the mass of one atom/molecule of that element.  Since $nN_a$ is the number of atoms/molecules, it will not make sense to have $\pi$ atoms or $1.5$ atoms, so $nN_a$ is a natural number.   By this mass is clearly discrete like charge. However, my textbook says the following     One of the main differences between charge and mass is that mass is continuous and charge is not.


Cardinality of an infinite union of finite sets

This follows  answer of .     Let $I$ an infinite set and $\{E_i\}_{i\in I}$ a family of finite   sets.      It is said that there exists an injection      $$\bigcup_{i\in I} \ E_i \to I.$$   In the comments, an argument with "$\aleph$ numbers" (which I haven't studied yet) is given.  I wondered how one could build this injection explicitely ? I have been trying for some time now, but it is quite hard to have intuition about that.


Zero to power Zero (Zero ^ Zero) indeterminable or not?

I want to know Zero power to Zero equal to 1 or Indeterminable. I think it cannot be exist. Please explain with proper mathematical definitions.


You have a deck of 32 playing cards. Somebody draws one card after another and shows them to you. At any point of time you may bet that the next card is black. If it is indeed black you earn $10, otherwise nothing. If you don't do anything you earn nothing as well. Find the optimal strategy.   In other words you should find the point of time where the quota of remaining red cards in the deck is maximal.   Any hints how to to this?


I have dd crashing after running a few hours.  Typically with a message like  Input/output error 68424+1 records in 68424+1 records out 342124883968 bytes (342 GB) copied, 5114.68 s, 66.9 MB/s   Is there something I can do about it?  Is there some way I can use the output? Or restart where it left off?  Is there any reason to think it is because the partition being backed up is being used?  It always crashes around 70-80%, often when the partition should be less-used.  Since this process takes so long, it is difficult to try different things.  I output to an image.  I could probably use a partition, but LVM is involved:  sudo lvmdiskscan /dev/centos/swap [       3.89 GiB]  /dev/sda1        [     500.00 MiB]  /dev/centos/root [      50.00 GiB]  /dev/sda2        [     465.27 GiB] LVM physical volume /dev/centos/home [     411.38 GiB]  /dev/sdb1        [     931.51 GiB]  3 disks 2 partitions 0 LVM physical volume whole disks 1 LVM physical volume   dd conv=sync,noerror if=/dev/centos/home bs=2000000   of=/run/media/ob/X_1T_Media1GHD-PCTU3/c/sd9e22_cel.image dd: error reading '/dev/centos/home': Input/output error 171062+1 records in 171063+0 records out 342126000000 bytes (342 GB) copied, 4625.3 s, 74.0 MB/s 220856+2 records in 220858+0 records out 441716000000 bytes (442 GB) copied, 6138.1 s, 72.0 MB/s   Friday Morning  ddrescue --sector-size=2048 --cluster-size=$((256*512)) --sparse --verbose /dev/centos/home /run/media/ob/X_1T_Media1GHD-PCTU3/c/sd7c_dd.image /run/media/ob/X_1T_Media1GHD-PCTU3/c/sd7c_dd.map  GNU ddrescue 1.18.1 About to copy 441714 MBytes from /dev/centos/home to /run/media/ob/X_1T_Media1GHD-PCTU3/c/sd7c_dd.image     Starting positions: infile = 0 B,  outfile = 0 B     Copy block size: 131072 sectors       Initial skip size: 32 sectors Sector size: 2048 Bytes  Press Ctrl-C to interrupt rescued:   441714 MB,  errsize:    8192 B,  current rate:        0 B/s    ipos:   342124 MB,   errors:       1,    average rate:   60675 kB/s    opos:   342124 MB, run time:    2.02 h,  successful read:       9 s ago Finished    But   extundelete sd7c_dd.image  --restore-directory /home/ob/p -o /tmp/tt extundelete: Bad magic number in super-block when trying to open filesystem sd7c_dd.image   /dev/mapper/centos-home on /home type xfs (rw,relatime,attr2,inode64,noquota)


How to find number of Subdirectories under a given directory

In windows you get a count of the number of subdirectories within a directory.Is there any equivalent on Linux ?  I'd like it to count recursively & Not stop at a single level.


How can I get list of symbols, abbreviations, abstract, acknowledgements into Table of Contents before Introduction, and under roman numerals?

I have managed to make a decent Table of Contents. However, it does not include the following items:   List of Abbreviations List of Symbols Abstract Acknowledgements   My Table of Contents has no problem listing the item from Introduction onwards (set in arabic numerals) but the items highlighted above (and set in roman numerals) do not appear. Basically, I want List of Abbreviations, Symbols, Abstract and Acknowledgement to appear BEFORE Introduction, and under roman numerals. Thank you so much.     I have posted my code below:  \documentclass[12pt]{article}   \usepackage{fullpage}   \usepackage{siunitx}    \usepackage{siunitx}    \usepackage[left=1.5in, right=1.5in, top=1.25in, bottom = 1.25in]{geometry}    \usepackage{amsmath, amsfonts, amssymb}   \usepackage{enumitem}   \usepackage{booktabs}    \usepackage{graphicx}   \usepackage{caption}   \usepackage{subcaption}   \usepackage{rotating}    \usepackage{placeins}    \usepackage[font=scriptsize,labelfont=bf]{caption}    \DeclareMathSizes{12}{12}{12}{12}    \begin{document}   \pagenumbering{roman}   \tableofcontents    \pagebreak   \listoffigures    \pagebreak   \listoftables %Includes List of Tables%   \pagebreak   \section*{List of Abbreviations}   \pagebreak   \section*{List of Symbols}   \pagebreak   \section*{Abstract}   \pagebreak   \section*{Acknowledgment}    \pagebreak   \pagenumbering{arabic}


I have a file that I report to daily using shell script. There are also colored texts in this report.  Normally, when the file is executed, color text is displayed, but when the result is saved to a log file and the log file is opened by Vim, the color code is displayed instead of the color.  I have no access to install any packages on the Linux.  I tried to find the answer but haven't found it yet!    if [ -t 1 ] ; then green=$'\x1b\x5b32m' reset=$'\x1b\x5b0m'   else  green= reset=    fi  echo -e "\n====== ${green}Instance Status${reset} ======\n"enter code here   Output file opened in Vim:  ====== Instance Status ======


How can I view all my unaccepted questions across SE?

I mean to get back them, really I do. So, how can I view all my unaccepted questions across the Stack Exchange network?  , but the stackexchange.com search doesn't work the same way (it searches for the text). Is there any way to do this?


I think my MacBook Pro battery was replaced by Apple's service team. How do I check that?

I handed my MacBook Pro (15" Touch bar) to the service centre in order to have the keyboard replaced. Now, when I check the battery cycle count, it shows "1". Before it was at "82".   Also, I'm getting a battery life of only 4.5 - 5 hours now.   Is there a way to find if my battery was replaced or not?


Map preserving intervals but discontinuous

Let $f:\mathbb{R}\to\mathbb{R}$ be a map sending closed intervals to closed intervals. Prove that $f$ is continuous or find a counter example.  WLOG we just have to prove continuity at $0$ and we can also assume that $f(0)=0$ and $f(1)=1$ (by considering $x\mapsto (f(x)-f(0))/(f(1)-f(0))$ ).  I build up this question while thinking of the question .


I have this:A piece of ice is gently placed on the surface of water filled in glass tumbler, so the water rises to the brim. What will happen to the level of water when the ice melts?  I still don't get it why the level of water remains the same. I tried to find out from other sources but they proved it using fancy physics formulas which I don't have and know currently. Please, can anyone give me a hand in this?


Should control variables be included in model if statistically insignificant?

I have a set of predictors in a linear regression, as well as three control variables. The issue here is that one of my variables of interest is only statistically significant if the control variables are included in the final model. However, the control variables themselves are not statistically significant.  Here is how the multicollinearity of all my variables look like (including control variables):   > vif(lm(return ~ EQ + EFF + SIZE + MOM + MSCR + UMP, data = as.data.frame(port.df)))        EQ      EFF     SIZE      MOM     MSCR      UMP   3.687171 3.481672 2.781901 1.064312 1.438596 1.003408   > vif(lm(return ~ EQ + MOM + MSCR, data = as.data.frame(port.df)))        EQ      MOM     MSCR   1.359992 1.048142 1.412658    My variables of interest are EQ, MOM and MSCR, and the control variables are EFF, SIZE and UMP. EQ is only significant if the three control var are included, and becomes insignificant when they are not:   Here are the coefficients (1rst row) and t-stats (2nd row) when control variables are included (notice that EQ is statistically significant)         intercept           EQ          EFF        SIZE         MOM       MSCR          UMP [1,] 0.005206246 -0.006310531 0.0001229055 0.004125551 0.007738259 0.00473377 5.838596e-06 [2,] 1.866628909 -1.746583234 0.0388823612 1.178460997 2.145062820 2.08131100 1.994863e-01  Now, here is the result of the regression when the control variables are excluded (notice that EQ is NOT statistically significant anymore)         intercept           EQ         MOM       MSCR [1,] 0.007313402 -0.002111833 0.007128606 0.00668364 [2,] 2.652662996 -0.595391117 2.036985378 2.80177366    The problem is that when I include my control variables, all my variables of interest are significant, but my control variables are not.  Which variables should I include in my final model? How should I structure my final model then, given the fact that the model will be used for forecasting?  Thank you,


Is gravitational acceleration less affected by relativistic mass increase?

Acceleration due to mechanical force will lessen due to relativistic mass increase as kinetic energy becomes significant near c.  But if acceleration is gravitational, the gain in relativistic mass will produce a corresponding gain in gravitational attraction, so acceleration should be constant (for large M and small m), even as m nears c.  But that would imply that c could be approached and exceeded.  What slows the acceleration to prevent m exceeding c?


Minecraft launcher could not connect to server?

What do I do? I looked at a similar question to mine and there was an answer saying to make sure Java is allowed past the firewall. So I checked and it already is. I've tried uninstalling and installing both Minecraft and Java but nothing has changed.  says that all services are fine, so what's going on? I bought a 2nd account to use as an alternative in-game account and now I can't log in.  (I cleared the email and password boxes for obvious reasons in this screenshot: security purposes)


Is there a noun that expresses the act of presenting false appearances?

I want to write about the Chinese Government during the Cultural Revolution and argue that whilst they created the appearance of more political openness, it was merely a façade.  Is there a word that expresses the inauthenticity of their actions? Like the 'falseness' of their policies but referring specifically to the fact that they pretend to be something they're not and that they hide something more sinister.


$\sum_{x+y =c}{a\choose x}{b\choose y} = {a+b\choose c}$

When trying to prove a problem I find that I need the above formula to be true, but I have no idea how to prove it. I am trying to prove that a given probability mass function is equivalent to a hypergeometric distribution and this identity pops up.


Check file is given extension type in C#

static void Main(string[] args) {    Console.WriteLine("Enter full file name with path:");    string strFileName = Console.ReadLine();     string FileEx =Path.GetExtension(strFileName);    Console.WriteLine("Your File Extension is {0}",FileEx);  }  output :  Enter full file name with path:  D:\MyFiles\TestFile.csv Your File Extension is .csv   Here I have a problem if I saved a text file in name of TestFile.csv it shows file extension is csv but I really want actual file extension even if given a fake file name  Eg : TestFile.csv ( Type of text file ) should give .txt output      TestFile.csv ( Type of csv file) should give .csv output  I think  it is not possible to attain this using above Function , any valuable advice will be helpful.  Thanks in advance


Proving $5^n \equiv 1 \pmod {2^r}$ when $n=2^{r-2}$

How can I prove that $5^n \equiv 1 (\bmod 2^r$) when $n=2^{r-2}$?   Actually what I am trying to prove is that the cyclic group generated by the residue class of $5 (\bmod 2^r)$ is of order $2^{r-2}$.


Suppose I have two securities A and B in India. I sell A at a profit of 100 INR, and B at a loss of 90 INR. Both transactions are short-term. So my net gain is 10 INR. But I buy B immediately afterwards. Am I still allowed to show my net gain as 10 INR?


How are Belgian fries different than the average French fries found in North America?

How do Belgian fries differ from the French fries we are accustomed to eat in the US and Canada in such places as McDonald's, Wendy's, Burger King and so on? Is it the variety of potato, the preparation involved or something totally different? What oil do they use in Belgium?   I remember having them while I was visiting family in Belgium. The fries were somewhat crispy and thicker than over here.


prove that if $p$ is a prime number, then $\sqrt{p}$ is an irrational number.

$\sqrt{p}$ is rational.  $\sqrt{p}=\frac{a}{b}$, where $a,b$ are integers with $\gcd(a,b)=1$. $a^2=b^2p$.    Since $p$ divides $a^2$, $p$ divides $a$.   $a=kp$.  $a^2=k^2p^2=b^2p$  $p=\frac{b^2}{k^2}\Rightarrow\sqrt{p}=\frac{b}{k}\Rightarrow\frac{a}{b}=\frac{b}{k}$ $b^2=ak\Rightarrow b=\sqrt{ak}$. $\sqrt{p}=\frac{a}{b}=\frac{a}{\sqrt{ak}}=\frac{\sqrt{a}\sqrt{a}}{\sqrt{a}\sqrt{k}}$ which has $\gcd(a,b)=\sqrt{a}\neq 1$ , a contradiction.   ($a\neq 1$ because the only number that divides 1 is 1, but 1 is not a prime from $a=kp$)  Hence, $p$ is irrational. Is this legit?


Two functions discontinuous, but sum continuous

I have some exercise that asks me this:  Find $f$ and $g$ discontinuos such that $f+g$ is continuous. This is what I tought:  $$f = \mbox{sign}(x)$$ $$g = -\mbox{sign}(x)$$  Where $\mbox{sign}(x)$ is the function that maps to $1$ if $x\ge0$ and $-1$ if $x<0$. Then, the two are discontinuous in $0$, but the sum, is continuous, because it's equal to $0$ in every point. First of all, is this example correct?  The exercise also asks me to find examples such that:  $f,g$ discontinuous, but $f$ composed with $g$ is continuous. (need help) $f$ continuous, $g$ discontinuous but the composite $f$ with $g$ is continuous.   (for the second one, if I take $g=\mbox{sign}(x)$ and $f=|x|$, then $fog = 1$. Is this right?  Could you guys give at least a hint, or a less poor example?


What's a good strategy for choosing which photos to keep?

Each time I upgrade my camera, the bigger file sizes (especially shooting RAW), my bigger memory cards and happier trigger finger mean that my new photos are consuming way more space.  I even have a 3TB primary drive and a 2TB backup drive - and they are getting fuller every day.  But going through photos and deleting bad ones can be a tedious process.  I've slowly been going through old photos and pressing delete if they are obviously out of focus or have too much motion blur.  But it still leaves a lot of photos that just seem uninspiring, or where I have a lot of photos that are very similar, taking up space.  Deleting them is actually a lot of work because for every string of 20 photos of something, there'll be a range that are of acceptable sharpness, some with good facial expressions or good framing, and so on, so it's never clear whether I'm actually keeping the best one - if not careful, I worry I'll delete one that was actually decent.   What is a good process for choosing what to delete and what to keep? At what stage of the process do think it's best to do it?


i am new to Linux,i have recently installed Ubuntu 14.04 alongside windows 8.Problem is when i boot into Ubuntu,my hard drives are not opening...it shows an error messege. *I have already done a disk check from windows everything is fine.The error shown is-  Error mounting /dev/sda2 at /media/rajnish/EC8A6A388A69FF86: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sda2" "/media/rajnish/EC8A6A388A69FF86"' exited with non-zero exit status 14: Windows is hibernated, refused to mount. Failed to mount '/dev/sda2': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.  And this is what i get on executing the command sudo fdisk -l yeah i know that..i always shutdown windows before logging into ubuntu. How to mount them in ubuntu? and this is what i get after executing the command sudo fdisk -l  Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x3efa4f7b     Device Boot      Start         End      Blocks   Id  System /dev/sda1   *        2048      718847      358400    7  HPFS/NTFS/exFAT /dev/sda2          718848   204802047   102041600    7  HPFS/NTFS/exFAT /dev/sda3       512002048   976771071   232384512    7  HPFS/NTFS/exFAT /dev/sda4       204804094   512002047   153598977    5  Extended Partition 4 does not start on physical sector boundary. /dev/sda5       204804096   302458879    48827392   83  Linux /dev/sda6       302460928   496001023    96770048   83  Linux /dev/sda7       496003072   512002047     7999488   82  Linux swap / Solaris  Partition table entries are not in disk order   Please help,thanks in advance


Can someone please explain in what cases the following syntax can be used and how does this work?  (function($) {     $.fn.hoverIntent = function(f,g) {     }; })(jQuery);   Thanks!


Why does Python in Linux require the line #!/usr/bin/python?

Pretty simple question: In Linux, why does Python require the line   #!/usr/bin/python   at the start of a python file, since Windows doesn't?  What does it do? 'cause the description "Links to Python" is a bit vague...


I have an Ubuntu 13.04 laptop, which is 32-bit.   I know there is no possible way for direct upgrade to Ubuntu 14.04. But how can I upgrade step by step, could you tell me how ?  Also in addition I tried many ways of upgrading, which includes downloading Ubuntu 14.04 .iso file form the Ubuntu website.


Use integration by parts to express $I(2n) =$ Integral of $\tan^{2n}x\mathrm{d}x$ in terms of $I(2n − 2)$.

(a) Use integration by parts to express $$I_{2n} = \int\tan^{2n}x dx$$  in terms of $I_{2n − 2}$  (b) Hence show that $$ \int_{\frac{\pi}{2}}^{\frac{\pi}{4}} \frac{1}{\tan^{4}x}dx =\frac{\pi}{4} − \cfrac{2}{3}$$  For part (a), I've tried turning $\tan^{2n}x$ into $\tan^{2n-2}x\tan^{2}x$ and then using integration by parts, but the answer is messy and i can't simplify it in terms of $I_{2n -2}$.  For part (b), I don't know where to start from after using the solution below for part (a).  Thanks


Assume n people who are initially assigned seats from 1 t0 n but they don't know their seat number, now they randomly pick up a seat on their own and what would be the probability that no one is seating to its assigned seat?


Why is 8 am (just after sunrise) darker than 12 pm (noon)? Does it have something to do with the geometry of spheres? Or is it due to the atmosphere?


LTSpice: How to convert netlist to .asc?

I have LTSpice on macOS. Is it possible to automatically convert a .cir netlist to .asc file? In other words, I would like to obtain the schematic file from the netlist. How could I do it? (I know that I can do the opposite, so from .asc to .cir)


How to prevent sql Injection? without modification into an SQL query

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to SQL injection, like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I have a view model that is shared between several actions. Is it possible to get the name of the action that is being called and, if so, how do I achieve that. I need the name of the action inside a custom validator function.


How to close (kill) ssh ControlMaster connections manually

With the following .ssh/config configuration:  ControlMaster auto ControlPath /tmp/ssh_mux_%h_%p_%r ControlPersist 4h   How to close the persisting connection before the 4 hours?  I know you can make new connections, but how to close them (all)?  Maybe there is a way to show all the persisted connections and handle them individually but I can not find it.


Are meta.stackexchange and meta.stackoverflow "one and the same"?

This seems counterintuitive to the vertical nature of Stack Exchange itself, but I cannot manage to browse to meta.stackexchange.com: I get redirected to meta.stackoverflow.com, instead.  This is also despite the fact that these URLs resolve to separate IP addresses...  ; <<>> DiG 9.7.3-P3 <<>> meta.stackexchange.com meta.stackexchange.com. 3421    IN  A   64.34.80.165  ; <<>> DiG 9.7.3-P3 <<>> meta.stackoverflow.com meta.stackoverflow.com. 684 IN  A   64.34.119.12   Am I being dumb somehow, or is this "the way it is"? If so, why?


This is a short story; written before 90s; where a man is in charge of a program to settle Jupiter; where they had developed some way of transforming human into Jupiter adapted life. Seems to work; but no one comes back. Man transforms self and dog in desperate attempt to figure out: turns out life so wonderful they didn’t go back either.


Proving a Binomial Summation with Induction $\sum_{k=0}^n(-1)^k \binom nk^2$

I'm attempting to prove that $$\sum_{k=0}^n(-1)^k{n \choose k}^2=\begin{cases}0&\text{if $n$ is odd}\\(-1)^m{2m \choose m}&\text{if $n$ = 2m}\end{cases}$$ via induction. Here's what I have so far: Base Case (odd): $n=1$ $$\sum_{k=0}^1(-1)^k{1 \choose k}^2=0$$ Base Case (even): $n=2$ $$\sum_{k=0}^2(-1)^k{2 \choose k}^2=-2$$ Hypothesis: $n=l$ $$\sum_{k=0}^l(-1)^k{l \choose k}^2=\begin{cases}0&\text{if $n$ is odd}\\(-1)^m{2m \choose m}&\text{if $n$ = 2m}\end{cases}$$ Inductive Step: $n=l+1$ $$\sum_{k=0}^{l+1}(-1)^k{l+1 \choose k}^2$$ I know that the goal is to get this sum into terms of the hypothesis plus the $(l+1)^{th}$ term, but I'm not sure how. I've tried manipulating various identities, but so far I'm not coming up with anything workable. Thanks in advance for any help.


How can I import a module from within a function, but have the imported module persist outside the function scope?

Question For a possibly convoluted reason (see below), I want to do something like the following: def import_np():     import numpy     return numpy.array([0])  def test_np():     return numpy.array([1])  Now if I try calling these two methods, the first works but the second doesn't: it says numpy is not defined. How can I fix this? Background I would like to import an in-house module of which we have many versions (edit: to clarify, we branch for every release). Ideally, I'd like to parametrise the import statement, but I can't do that, so I thought I could have a function that looks like this: def import_version(path_to_version):     sys.path.append(path_to_version)     import the_module  However, I can't use the_module outside of this method, which has led to my question above.


Why isn't dark matter just ordinary matter?

There's more gravitational force in our galaxy (and others) than can be explained by counting stars made of ordinary matter. So why not lots of dark planetary systems (i.e., without stars) made of ordinary matter? Why must we assume some undiscovered and unexplained form of matter?


When is an Integer a Rational Number, and are All Ratios Rational, Even $\frac{\sqrt{7}}{2}$?

$$\Bbb{Q} = \left\{\frac ab \mid \text{$a$ and $b$ are integers and $b \ne 0$} \right\}$$ In other words, a rational number is a number that can be written as one integer over another. For an integer, the denominator is $1$ in that case. For example, $5$ can be written as $\dfrac 51$.  Is $5$ a rational number? Or is $\dfrac 51$  a rational number? I'm not able to figure out what the definition is actually saying. What are the numbers that cannot be written as one integer over another?  Irrational numbers are the numbers that cannot be written as one integer over another. Roots of numbers that are not perfect squares are examples of irrational numbers.  However, what is this then: $\dfrac {\sqrt 7} {2}$?


What kind of file path starts with "\\.\"?

I use Avast Web Shield, and it intercepts TLS traffic from the browser using the env variable: SSLKEYLOGFILE  \\.\aswMonFltProxy\FFFFDE812B3DD840 While I don't actually mind that it does this, and I understand why it does so, I got curious as to what this "path" actually points to. My first thought is this is either some kind of Netbios address or a socket connection, but I really have no idea. Does anyone have any idea what this kind of "path" is and if it's actually mappable to a physical file on the disk or maybe in memory?


Can I improve download-speed by connecting two 4g-routers?

I have mobile Internet at home with one Huawei B593 4g-router. When it works it's pretty fast, around 17 Mbits/s down, but the service is unstable and I would frankly like it even faster. If i get one more internetsubscription so that I have two routers, each with its own simcard and subscription, would it be possible to connect them in a way that I got double download-speed and redundancy (if one malfunctioned the other would still be working). I would be willing to build a new computer to get this to work so just tell me what i would need. Thanks in advance.  Andy


Extend a language with additional keywords?

I'm using listings and I want to extend a language with additional keywords for highlightning. I know there is an option morekeywords available, but that only works for a particular lstset declaration and I don't want to have to copy-paste all keywords into all listings. I've tried declaring the keywords as part of a command but that doesn't work (probably because the command is not expanded and I don't know how to fix that).  So is there any way of declaring a new language by copying an existing one and just adding more keywords?


I'm trying to create a linq join statement which joins an object from a table based on two conditions  MESSAGES ====== ID (int) UserID (Guid)  MESSAGEPART ====== MessageID (int)  IsPlaintext (bool) MessageContent (nvarchar(max))   Here's the query I want to write, essentially:   var messages = from m in db.Message                 join p in db.MessagePart on m.ID equals p.MessageID                                          and p.IsPlaintext equals false   Unfortunately, this doesn't work. This is the best I can do.   var messages = from m in db.Message                 join p in                (from x in db.MessagePart where x.IsPlaintext == false select x)                 on m.ID equals p.MessageID   This seems a bit longwinded. Is there a more elegant way of achieving it?


I use nano <file_name> to open/edit files on my remote Digital Ocean server (running Ubuntu 16.04). However it's very hard to edit so is there a way to open these files in TextEdit?  I tried to use the proposed solutions below but they do not work:  open -a TextEdit <my_file_name> and open -a TextEdit both return this:  open: invalid option -- 'a' Usage: open [OPTIONS] -- command  This utility help you to start a program on a new virtual terminal (VT).  Options:   -c, --console=NUM   use the given VT number;   -e, --exec          execute the command, without forking;   -f, --force         force opening a VT without checking;   -l, --login         make the command a login shell;   -u, --user          figure out the owner of the current VT;   -s, --switch        switch to the new VT;   -w, --wait          wait for command to complete;   -v, --verbose       print a message for each action;   -V, --version       print program version and exit;   -h, --help          output a brief help message.   open -e <my_file_name> returns:  Couldn't get a file descriptor referring to the console   so I tried an alternate method I found.  I added alias textedit='open -a TextEdit' to my .profile. After that I tested it with textedit settings.py and it returned  The program 'textedit' is currently not installed. You can install it by typing: sudo apt install xview-clients   So I installed it - but after I tried textedit settings.py again, it returned:  XView error: Cannot open connection to window server: :0 (Server package)   Any idea?


Integration help containing exp and square root

Integrate this $$ \int_{-\pi}^{\pi} \frac{e^{-inx}}{\sqrt{x^2+a^2}} \, \mathrm{d}x $$ Here $a$ is a constant.


What did Mace Windu mean when he said that Anakin is too old to become an apprentice?

There is a scene in  where the members of the Jedi Council tell Qui-Gon their decision about Anakin:     MACE WINDU : He is too old. There is already too much anger in him.   Did Mace Windu actually mean Anakin's biological age?  It is well known that Anakin was 10 years old at the time of The Phantom Menace. Is this age really too late to become a Jedi apprentice? As we  Obi-Wan was even older (12 years old) when he became an apprentice.  Maybe, it was just an excuse to deny? Or..  Is it possible that he did actually mean something different?


Please help me, Group Theory. Prove $b^{33}=e$.

Let $G$ be a group and $a,b \in G$. Prove that if $a^{2}=e$ and $ab^{4}a=b^{7}$, then $b^{33}=e$, where $e$ is the identity of a group $G$.


Proving that $\limsup {x_{n}} = \lim_{n \rightarrow \infty} ( \sup _ {m \geq n}  x_{m} )$.  I want to prove it using only the definition of the $\limsup {x_{n}}$: that $\limsup   {x_{n}}$ is the largest accumulation point of $\{x_{n}\}$.  I have seen many links for the proof here but as far as I understand not directly from this definition and after reading them all I got confused, could any one help me in proving this?


Is my proof that $\frac{\pi}{4}=\sum\limits_{n\geq 0}(-1)^n \frac{1}{2n+1}$ correct?

Respected All  I was trying to prove that  $$\sum_{n\geq 0}(-1)^{n} \frac{1}{2n+1}=\frac{\pi}{4}$$ What I tried to show like this.  We know  $$\frac{1}{1+x^2}=(1+x^2)^{-1}=\sum_{n\geq 0}(-1)^nx^{2n}, |x^2|<1$$ Integrating term by term with in interval of convergence we get  $$\int_0^{x_0}\frac{dx}{1+x^2}=\sum_{n\geq 0}(-1)^n\frac{x_0^{2n+1}}{2n+1}$$ Taking $x_0=1$ we have  $$[\arctan(x)]_0^1=\sum_{n\geq 0}(-1)^n \frac{1}{2n+1}$$ i.e. $$\frac{\pi}{4}=\sum_{n\geq 0}(-1)^n \frac{1}{2n+1}$$  Am I right?


What intuitive notion is formalized by "natural transformation" in category theory?

Mac Lane once said that he didn't invent category theory to study categories, but to study natural transformations.  But googling around a bit, I haven't found out what natural transformations intuitively are about (only their definition).  I want to ask:    What is the intuitive notion formalized by "natural transformation" in category theory, and (in the simplest possible terms) why does this formalization capture that intuition? Do category theorists in general still agree with MacLane's statement that natural transformations are the raison d'etre of category theory?   To clarify what I mean with an analogy:   A topology on a set $X$ formalizes the intuitive notion that each point $x\in X$ "touches" some subsets of $X$ but not others. If a set $X$ has a group structure, this formalizes the intuitive notion that elements of $x$ can be seen as "invertible actions" that can be applied in succession. Natural transformations (and their base concept Functor) formalizes the intuitive notion that ...


Generate random Password with Special Characters?

Is there a way to use the below code, but also add special characters? I need to generate a random 8 character password, that includes special characters. Is this possible? Any assistance will be welcomed      public static String generatePassword(Integer len) {          Blob blobKey = crypto.generateAesKey(128);         String key = EncodingUtil.convertToHex(blobKey);                  System.debug(key);          return key.substring(0,len);     } }


If $f:[0,1] \rightarrow \mathbb{R}$ is continuous function such that $f(0)=f(1)$ then there exists $ x\in [0,1]$ such that $f(x) = f(x+\frac{1}{n})$.

If $f:[0,1] \rightarrow \mathbb{R}$ is a continuous function such that $f(0)=f(1)$, then there exists $ x\in [0,1]$ such that  $f(x) = f(x+\frac{1}{n})$, where $n$ is any natural number.  Let $g(x)=f(x+\frac{1}{n})-f(x)$ on $[0,1-\frac{1}{n}]$. Now, $f$ is continuous function on closed interval.So, it must attain its bounds. Let $m$ be minima at $c_1 \in [0,1]$ and $M$ be maxima at $c_2 \in [0,1]$.  Now if $c_1,c_2 \in [0,1-\frac{1}{n}]$, apply IVT to $g(x)$ on $[c_1,c_2]$.  If $c_1$ or $c_2 \in [0,1-\frac{1}{n}]$, apply IVT to $[c_1,c_1-\frac{1}{n}]$ or  $[c_2,c_2-\frac{1}{n}]$ respectively. If  $c_1,c_2$ both do not belong to $[0,1-\frac{1}{n}]$, then apply IVT to $g$ on $[c_1-\frac{1}{n},c_2-\frac{1}{n}]$.  Is this proof correct? Thanks.


Add android-studio/bin/ to PATH environmental variable

Recently I installed Android Studio. Now I want to add android-studio/bin/ persistently to PATH environmental variable as Session-wide environment variables and not as System-wide environment variables. To do that I tried to edit ~/.profile as described . So I have these at the end of ~/.profile:  if [ -d "$HOME/bin" ] ; then     PATH="$HOME/bin:$PATH:/usr/local/Android/android-studio/bin" fi   Then I re-login to initialize the variable. But when I run studio.sh in terminal, I get this:     studio.sh: command not found   Here are results of $PATH and echo $PATH:  $ $PATH  bash: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games: No such file or directory  $ echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games   Also I'm sure that ~/.bash_profile and ~/.bash_login do not exist. Now what cause the problem and how I can solve that?  Edit:  I change end of ~/.profile to this, but it does not work:  # set PATH so it includes user's private bin if it exists if [ -d "$HOME/bin" ] ; then     PATH="$HOME/bin:$PATH"     PATH="$PATH:/usr/local/Android/android-studio/bin" fi


I have a 5 year old notebook computer. It uses Windows XP, and as you might know, this OS now has no support at all. It has a 1.60GHz, 0.98GB of RAM.  What would you guys recommend me , in order for me to happily migrate from Windows XP to Ubuntu program.  I appreciate in advance any help you can provide me regarding this matter.  Regards


Apex compile error : variable does not exist

I'm having issues with creating a pretty simple test Utility Class. I want to create two records: an account and a related child contact. The error I see in the developer console is:     Variable does not exist: a.ID   My code, based on the Salesforce Apex Workbook, is as follows. I've played around with various things, but it's not working. Where am I going wrong? Thanks in advance.  @isTest public class AccountSaveTestSuite {      public static Account createOneAccount(){           Account testAccount = createAcct('ABC Computing inc.');              Contact testContact = createContact();          return testAccount;             }      // Helper methods //     //        private static Account createAcct(string accountName) {          Account a = new Account(             Name=accountName);         insert a;         return a;     }      private static Contact createContact(){         Contact c = new Contact (             FirstName = 'Jane'              , LastName = 'Smith'             , Account = a.ID); // *** Error is here ***         insert c;         return c;      }  }


How to make a declaration from a command?

There are two forms of setting the type style: the declarative method e.g, \itshape and the command form, e.g, \textit. The command form takes an argument whereas the declarative form does not --- it just applies itself to whatever comes afterwards.  I would like to develop a declarative form, say \UppercaseIt, of the command form \MakeUppercase{<text>}. I have read, in source2e.pdf on CTAN the code for implementing \textit, \itshape and \MakeUppercase and can't claim that I understand any of them. I am after something like {\UppercaseIt some text} instead of \MakeUppercase{some text}.  I only have a code outline of what I'm after, since I don't know how to do it:  \documentclass{article}  \newcommand{\UppercaseIt}{%   %... magic }  \begin{document}  \MakeUppercase{some text}% Yields SOME TEXT  {\UppercaseIt some text}% Should yield SOME TEXT  \end{document}


Recently, I have to work with some problems that require to draw table like below in LaTeX. I used to think about diagonal line inside a cell, but it's not a good choice for this problem since the texts are not in diagonal direction. Does anyone create something like this in LaTeX, can you suggest me any solution


prove that $f_n = 37111111...111$ is never prime

Let $$f_n = 37111111...111$$ with n 1's.  Prove that $$f_n$$ will never be prime for $$n\ge1.$$  I tried to look $$f_n$$ in mod(p), assuming $$f_n$$ is prime, for the sake of contradiction. I also tried to apply Wilson and Fermat's small theorem.   I'm sure there must be a simple factorization which I'm overseeing.


Holomorphic function $f$ such that $f'(z_0) \neq 0$

Let $f: \mathbb{C} \rightarrow \mathbb{C}$ be an holomorphic function such that $f'(z_0) \neq 0$ for some $z_0 \in \mathbb{C}$.Prove that there is $r>0$ such that, if $|z-z_0|<r$ and $z \neq z_0 $, then $f(z) \neq f(z_0)$.  It seems very trivial, but I can't solve it...


Can I change the color of the folders in iOS7?

I want to change the folder colors on my home screen. Can it be done?


Windows won't boot File: \ubuntu\winboot\wubildr.mbr

I am really new to Ubuntu s i don't normally use it but i have to install it on my laptop for my computer course. My laptop runs on Windows 7 and it is pretty new. I downloaded and installed Ubuntu via Windows Installer from the website, however, when i restarted the computer and tried to boot the computer using Ubuntu, the following message appears:  Windows failed to start. A recent hardware or software change might be the cause. To Fix the problem:   1. Insert your Windows installation disc and restart your computer.  2. Choose your language settings, and the click "Next."  3. Click "Repair your computer."  If you do not have this disc, contact your system administrator or manufacturer for assistance.  File: \ubuntu\winboot\wubildr.mbr Status: 0xc0000098 Info: The selected entry could not be loaded because the application is missing or corrupt.   As I said, I am really new to Ubuntu. I have searched up the issue and found some solutions but they sound quite complicate and I have no idea what to do. Can somebody help me please? Thank you very much.


Application launchers in '/usr/share/applications' not working in Nautilus

After installing the latest Ubuntu I find that the icons in the applications folder (viz. /usr/share/applications), when opened in the Files application (Nautilus), come up as a blank page with a gear in the middle. If I try to open them I get a read only text box.


Is a 18% gray card intended for exposure metering, and its use to set white-balance is just a bonus?

I've heard that 18% gray cards are intended specifically to aid on determining the right exposure for photography, and only coincidentally for white balance. Is this true? Is it better to use a different type of aid for setting white balance?


Auto-Snap a Terminal (or Nautilus) when Opened

Like 98% of the time I open a Terminal or Nautilus, I want to use it snapped to the right/left... especially if I am using more than one instance of them.  Can I configure my Ubuntu to open any instance of Nautilus or Terminal in 'snapped' mode?  I am using Ubuntu 15.10.


Solve the exponential-trigonometry equation

I have the problem $$ 3^{\sin x} \cdot 3^{\sin 2x} \cdot 3^{\sin 3x} \cdot \ldots = 3. $$  I’ve converted it to $$ \sin x + \sin 2x + \sin 3x + \ldots = 1, $$ but what should I do next?


How can I obscure what I am using to run my site?

Is there anything I can do to prevent somebody from knowing my site is using Drupal by looking at the source code of the front page? I am referring to people who scan sites using software that detects the software used to run the website to be able to attack it using any known weak point.  If it is not possible to completely hide the fact that the site is using Drupal, is it at least possible to confuse them (e.g., by aliasing the node pages with URLs like http://example.com/servlets/<node-id>.jsp)?


A simple block cipher based on the SHA-256 hash function

I've come up with this little routine for doing encryption using the SHA-2 (in this case SHA-256) hash function. As such it is a block cipher with a 256 bit (32 byte) block size and an arbitrary key length. It's easy to see that you could replace the hash function and get an entirely new type of algorithm.  I want to know if there are any problems, especially flaws, in this construction, and whether algorithms of this type have been studied.  Initialization with key:  $$ S_0 = H(k) $$  Encryption for plaintext blocks $P_1, \dots P_n$:  $$ S_i = H(S_{i-1})$$   $$ C_i = P_i \oplus S_i $$  Decryption for ciphertext blocks $C_1 \dots C_n$:  $$ S_i = H(S_{i-1})$$   $$ P_i = C_i \oplus S_i $$  Here is some sample C source code using SSL:  #include <openssl/sha.h>  struct sha_crypt_state {     unsigned char digest[SHA256_DIGEST_LENGTH]; };  void sha_crypt_set_key( sha_crypt_state *state, unsigned char *key, int key_length ) {     SHA256( key, key_length, state->digest ); }  void sha_crypt( sha_crypt_state *state, unsigned char *block ) {     sha_crypt_state temp;     SHA256( state->digest, sizeof(state->digest), temp.digest );     memcpy( state->digest, temp.digest, sizeof(temp.digest) );      for ( int i = 0; i < sizeof(state->digest); ++i ) {         block[i] ^= state->digest[i];     } }  void sha_crypt_test() {     const char *key = "secret";      // prepare a test block     char block[SHA256_DIGEST_LENGTH];     memset( block, 0, sizeof(block) );     strcpy( block, "Hello, testing encryption!" );      // test encrypt     sha_crypt_state state;     set_key( &state, (unsigned char *)key, strlen(key) );     sha_crypt( &state, (unsigned char *)block );      // test decrypt     set_key( &state, (unsigned char *)key, strlen(key) );     sha_crypt( &state, (unsigned char *)block ); }


Is this type of a subgroup always normal?

Let $G$ be a finite group, and let $H$ be a subgroup of $G$ such that the index $(G\colon H)$ of $H$ in $G$ is the smallest prime that divides the order of $G$. Can we say anything about whether or not $H$ is normal in $G$?   The answer is of course yes if $G$ is abelian.


How to stop my iPhone from asking me to enter my password?

OK. So after the Apple hack when celebrity nudes were stolen I changed my password to something more complex than I can easily remember. (My password is now stored in the password manager app and is something like this u7GhY53bAhh2x.)  When I was buying this latest iPhone the sales rep at the Apple store assured me that I will no longer need to enter my password because the phone can read my fingerprint that is very secure, blah-blah-blah. So I set this all up and then what... now when I try to download a new app the thing pops up and wants me to enter my password. The praised fingerprint doesn't seem to do anything. So OK I entered my password (which now basically required a trip to the password manager program and a process of copying it letter-by-letter.) This was about a couple of weeks ago. Today, I was trying to write a review for another app and guess what -- that same annoying password window came up & wanted me to enter it again. So where is that fingerprint thing again?  Can someone explain how to make it work with the fingerprint and not bug me with entering the password over and over again?


Dynamic SQL operator IN with multiple parameters

I'm using XML to create a dynamic SQL Query. I need to use the operator IN, but I can't make it work with multiples values.  To illustrate my matter here is what does work :  exec sp_executesql N'SELECT * FROM commercial_element WHERE specific_info IN (@IncludedListB)                 ',N'@IncludedListB nvarchar(30)',@IncludedListB='BAR'   The parameter @IncludedListB is built as a string in C#  filter.IncludedListB = 'BAR';   What I am trying to do is passing multiple paramters in the operator IN :  exec sp_executesql N'SELECT * FROM commercial_element WHERE specific_info IN (@IncludedListB)                 ',N'@IncludedListB nvarchar(30)',@IncludedListB='''BAR'',''BSO'''   Building like so :  filter.IncludedListB = ''BAR','BSO'';   Focusing only on the SQL Why does my second query doesn't work ? I'll figure it out for the C#.


Stack Overflow seems to have abandoned us iOS users! Look:    What has happened?!   App Version: 1.6.6.2 Device: iPhone 5s (Global) OS Version: Version 10.3.2 (Build 14F89)


How many ways to make a bracelet with $n$ white balls and $m$ black balls?

Okay so I have $n$ black ball and $m$ white balls. How many bracelets can I make using all the balls? At first I thought there are $(n+m-1)!$ if all the balls were different. So we can divide into groups of $n!\cdot m!$ that look the same if you permute the black balls between them and also for the white balls.  However if I had $6$ white balls and $2$ black this would yield $3.5$ so clearly this can't be correct. How can I count this?  Is there a generalized version form for $k$ colors?


Gauge Higgs unification .  Does gauge higgs unification has been proved ？ If so , what is it exactly meaning ?


How do I find entropy of features having numerical data?

I'm a newbie and I'm writing a decision tree from scratch using entropy and information gain. I understand that entropy is the measure of impurity of a data set and also calculated entropy for categorical features but for continuous data, I do get an intuition that I have to take a range of values for each class label but how do I choose that range? Is my intuition correct? What is the standard way of finding the entropy of a feature with numerical data.


Does this recording sound like the pulses emitted by bats?

Out of curiosity, I recorded sounds in an area with lots of bats, hoping to be able to "hear" the bats communicating by lowering the ultrasound to a level down to the frequency which can be heard by a human. After a bit of post-processing, I actually hear interesting sounds, but I'm not sure about the origin. It seems that the frequency of the pulses is too low compared to bats. . Are those actual sounds emitted by bats? If not, what other animal could be the source of those sounds? About the audio The sound was recorded at 10 p.m. at  near a river, with more of a dozen bats flying in this zone. There is a bridge nearby, and the sides of the river are flat concrete, which means that there are a lot of opportunity for sound reflection (although high frequency sounds don't reflect well). Zoom H5 with the default XY directional microphone was used. The bitrate was set to 24-bit. Unfortunately, I used the sampling frequency of 48 kHz instead of the maximum 96 kHz. The following transformations were made to the original audio:  The pitch was shifted by -12 semi-tones, which means that the 20 kHz sound becomes 10 kHz, and 15 kHz becomes 7.5 kHz.   All sounds below 6 kHz were removed.  The sound was amplified.  Severe noise reduction was applied to eliminate everything but the actual sounds emitted by the bats.   The empty parts of the audio were removed.  The sound was amplified once again.   Frequency The frequency analysis of the transformed audio a peak around 9 kHz (18 kHz in the original audio), slowly fading to suddenly drop at 16 kHz (32 kHz in the original audio).   contains many sources with different indications about the frequency range of the sounds emitted by bats, only a few referencing the frequencies low enough to be heard by a human:  Frequency Produced 10kHz-120kHz Ramsey, Gabriel, McGuirk, Phillips, Watenpaugh. Holt Physical Science. New York: Holt, Rinehart and Winston Publishers, 1986.  while most agreeing on the fact that bats use frequencies higher than 20 kHz.  Most bats use frequencies in the range 20-80 kHz, only a few bats use frequencies less than 20 kHz. Long, M.R. & Savage, J.G. Mammal Evolution. New York: Harper, 1976: 108.  The observed range of 18..32 kHz seems too low compared to the sources, but I have an impression that the frequencies vary a lot between different species of bats. Pattern When viewing the audio track (see below), each cry consists of several pulses in two to three sub-groups which are in turn in two groups. Each peak is a bit less than 1 ms. The second group occurs from 40 to 200 ms. after the end of the first one. Each sub-group is separated by 5 to 10 ms. The frequency of every pulse doesn't vary, except the very first pulse. The first cry starts by a more quiet pulse at 6 kHz (12 kHz in the original audio). The second and third cries don't follow this pattern.  indicates that there are three categories of sounds emitted by the bats:  Short clicks,  Frequency-swept pulses,  Constant frequency pulses.   It looks like it's still the third category which we are observing here, and the overall pattern looks similar to the one described for the bats. The gap between the left and the right track is mostly irrelevant: at higher frequencies, microphones become more and more directional, and the sound is reflected less, which leads to such difference.     Note: this question was considered to be on-topic at Biology.SE on .


How to increase my chance for being admitted to a PhD if my MSc is in a different topic?

I have a MSc degree in Computer Science from a well known university, but the problem is that my degree is, for example in Computer Graphics. Now I would like to study PhD in computer Science, but related to another topic such as Green Computing.    How I can convince the admission committee or the Professor in charge of the research group that I can be a good student in his group?  One friend told me that one important thing is the motivation letter others about the research proposal (which for me is somewhat not so clear, because for what I know one do a research proposal only when one is inside a group)  Any help will be valuable? I have applied to a lot of PhD positions and the frustration is getting higher with each rejection.


I know that embedding CSS styles directly into the HTML tags they affect defeats much of the purpose of CSS, but sometimes it's useful for debugging purposes, as in:
asdf
   What's the syntax for embedding a rule like:  a:hover {text-decoration: underline;}   into the style attribute of an A tag? It's obviously not this...  bar   ...since that would apply all the time, as opposed to just during hover.


How to interpret regression coefficients in logistic regression?

I have run the following logistic regression:  glm(formula = DecisionasReceiver ~ L1 + L2 + L3,    family = binomial("logit"), data = lue)   where L1 L2 and L3 code for differences in condition of no.GREEN. L1: 1,-1,0,0 : is there a difference in DecisionasReceiver as no.GREEN changes from 1 to 2?  L2: 0,1,-1,0: is there a difference in DecisionasReceiver as no.GREEN changes from 2 to 3?  L2: 0,0,1,-1: is there a difference in DecisionasReceiver as no.GREEN changes from 3 to 4?  And I'm running this regression both for the cases where MessageReceived is BLUE and for MessageReceived RED.   I have the following output:     Coefficients:       Estimate Std. Error z value Pr(>|z|)     (Intercept)  -0.9535     0.3659  -2.606  0.00916 **  L1            2.2753     0.5406   4.209 2.56e-05 *** L2            3.1234     0.7318   4.268 1.97e-05 *** L3            1.9369     0.8134   2.381  0.01726 *     Looking at my graph it seems strange that the coefficients are positive and that the intercept is -0.953. How exactly should I interpret these results in the light of the graph?


My computer keeps asking me to update but there is no space, boot memory at 100%.  Have tried apt-get clean, sudo apt-get clean and sudo rm .xsessions-errors.   None of which work. Any suggestions greatfully received.  NB, I am NOT a computer whiz so baby steps PLEASE


How can I draw a line with length "a^2"?

I have a line whose length is "a". Can anyone explain procedure of drawing following lines?  1-line whose length is "a^2"  2-line whose length is "sqrt(a)"


Connection between rank and matrix product

I have a problem understanding the following:     Let $A$ be an $m \times n$ matrix and let t $\in \mathbb{N}$. Prove that   $\operatorname{rank}(A)\leq t$ if and only if there exists an $m \times t$ matrix $B$ and a $t \times n$ matrix $C$ so that $A = BC$.   I know what a rank is but I can't make a connection between the rank and the existence of two matrices such that $A = BC$.


start section numbering with 0 not 1 LaTex article class

In my thesis, my examiners need the section numbering to start with 0 and not from 1.  The structure is somewhat like  \documentclass[12pt]{report}  \begin{document} \chapter{First} \section{first section}  \subsection{subsection}  \end{document}   which gives me result as      Chapter 1      First      1.1 first section      1.1.1 subsection   instead of this I need      Chapter 1      First      1.0 first section      1.0.1 subsection   I tried using   \setcounter{section}{-1}   before   \begin{document}   but no success.


Why do 'organization' and 'organisation' both seem to be commonly accepted spellings, and when is one used over the other?

Looking at several online dictionary resources, it seems that the accepted spelling of "organization" is with a 'z', however, even on this site, "organisation" is frequently used as the spelling.  Why the difference, and when is it appropriate to use one over the other?  EDIT: Here is a link to the Oxford Dictionary article, just for ease of reference:   The link for the non-American-English article as well:


I need to search a line in a 3D space. I have a starting point (coordinates) of the line and the angle at which it is suppose to go (relative to each of the axis). I need to start from the starting coordinates and search every element (every coordinate contains an element) $1$ by $1$ until I find one that matches the condition.  Imagine a bullet going through air to some target.  Doesn't seem that hard, but I haven't managed to find the solution for this.  In 2D space this would be something like      $$y = x\cos(\mbox{angle}) + \mbox{startPosition}$$    I assume you'll need $2$ formulas for my problem. Any idea how to solve it?


How do we know the universe is expanding, and not that its contents are shrinking?

Is there a physical reason why not to think that instead of space expanding, all physical constants and parameters are shrinking (including of course the instruments we use to measure the constants) and space is static, or is it a case of Occam's razor?


Mutual fund value went down, shares went up, no action taken by me

I have no prior experience with stocks so please forgive me if this is a dumb question but I don't even know what to try googling. Two days ago I signed up with scottrade. I put $1000 into ICENX mutual fund. It got me ~56 shares. Today I log in and I see this:    What has happened? Apparently the share price took a huge plunge but my shares magically multiplied? Why does it say I lost $258 if I actually gained $12? Thank you guys so much!


Is it possible to search for words containing accented characters in chat?

If I remember correctly, on the main site the search is "accent-blind" in the sense that, for example, searching for  and  returns the same set of result. (Perhaps in different orders, exact matches might be considered more relevant.) Similarly for  and .1  However, when I search in chat, searching for  does not return messages containing José. I am not sure how exactly are the messages returned when searching for  selected. But when I actually want to find messages containing the word José, I have to search for .  Similarly, if I want to find messages containing the name François, I have to search for  or . (In short, this works as if the word was a part between two accented characters, or if there is only one then between the accented character and the beginning/end of the word.) I get completely different sets of results for  and for .  If the word contains more accents, search seems to be more complicated. I have just tested  that messages containing the name Désirée are found when searching for . They are not among the results if I search for  or , that message is not among the search results.   Is it actually possible to search in chat for words including accented characters (such as the examples above)? Did I miss some trick I should have used? If not, could some similar functionality as in the search of main be implemented.    I suppose that if there is name with accented characters, some users will use it in that way and some will transcribe it. (Especially if something is copy-pasted from somewhere, it is likely to contain accented characters.) If somebody is looking for past messages containing this name, AFAICT they have to do several searches.  1See, for example, this feature request which is marked : .


I installed 10.10 a few days ago. The only changes to the default install are the addition of Chrome and Pinta.  It was fine for a few days, then today login etc seemed slow. Likewise it couldn't even render the restart/shutdown menus.  Hoping it was some botched update, I ran the update manager; it tried to install but failed (the UI didn't make it obvious what had failed).  Fine, ok. Shut it down (press enter on the blank shut-down dialog).  Fire it up hoping... And... #fail.  Target filesystem doesn't have requested /sbin/init. No init found. Try passing init= bootarg.   Is it now a brick?     More details:  GRUB 1.98+20100804-5ubuntu3   With  Ubuntu, with Linux 2.6.35-22-generic   Causes  udevadm trigger is not permitted while udev is unxonfigured Giving up waiting for root device.   Or  Ubuntu, with Linux 2.6.35-23-generic   Causes  mount: mounting /dev on /root/dev failed: No such file or directory   Then the same for /sys and /process


What is Stack Overflow, or in general, Stack Exchange's standing on (innocently positioned) personally identifiable data?  For instance, this following post has information that may be PID. It may or may not belong directly to the author, but could be an innocent byproduct of a naive user not understanding the implications!    What are the guidelines in such a case? Should we simply edit it and replace it with Chuck Norris' data, or flag it?


When I click on an XML feed in Firefox it automatically detects this and asks how I would like to subscribe. Is there an easy way to just see the raw feed in Firefox?  This is simple in Google's Chrome browser, since it doesn't do anything. But I am guessing a future version will handle it as Firefox does.


Radius of Convergence for series in $z^{3n}$ using Cauchy-Hadamard formula

If $∑ a_nz ^n$ has radius of convergence R, use the formula $R = \left( \limsup_{n \to \infty} | a_n |  ^{\frac{1}{n}} \right)^{-1} $ to find the radius of convergence of $∑ a_nz^{ 3n}$ I tried to solve this question using the ratio test, I got an answer of $R^{\frac{1}{3}}$, however, I am not sure how to solve it using Cauchy-Hadamard formula. Any hint will be appreciated.


What is the noun of "Receive"? I need to frame this sentence :      This is the date of your (Receival/Receiving/receipt).   What is the right answer?


The :  :    :    :    And, my favorite, :    But  is very boring:    Yawn.    And it isn't like I'm seeing this infrequently - we get spam, it is deleted and then I click the X new questions button, open them all in new tabs and half of them are deleted and end up with a 404.  Please could we have a fun, inventive image, maybe that links into one of . Feel free to answer with your suggested images (ensure it would be legal for it to be used).  Please note however that SE have not said that the 404 page will necessarily be implemented since I have no saying on that.


What is the name of the function $f(k) = \text{max}(k,0)$ on $\mathbb Z$?

Let $k\in \mathbb Z$; is there a name for the function $f(k)$ below? $$ f(k) = \text{max}(k, 0) $$


Is there a way to find results that match either one tag or another (with or without a keyword included?)  For example searching  [x] [y] will return content with both [x] and [y] - can I preform a search to find content with tags [x] or [y]?


I tried searching around, but I couldn't find anything that would help me out.  I'm trying to do this in SQL:  declare @locationType varchar(50); declare @locationID int;  SELECT column1, column2 FROM viewWhatever WHERE CASE @locationType     WHEN 'location' THEN account_location = @locationID     WHEN 'area' THEN xxx_location_area = @locationID     WHEN 'division' THEN xxx_location_division = @locationID   I know that I shouldn't have to put '= @locationID' at the end of each one, but I can't get the syntax even close to being correct. SQL keeps complaining about my '=' on the first WHEN line...  How can I do this?


I mean to say that anybody can hatch a chicken's egg under a toad, (even Neville can do that with his own toad ), so why are they so rare that there is only one in all of Hogwarts?


I have a friend who lives in Atlanta, Georgia. There is a guy she met on Facebook who stays in Malaysia but originally from Nigeria.  This guy asked to send her money and open lots of accounts, transfer the money, withdraw it and pay it to these guys. She is promised to get a percentage from the transactions.  Is this a scam?


What do you think about puting regulators lm75xx in series in order to get less heat loss as possible :  9v-- to 5v-- to 3.3v , to get 3.3v from 12v supply?  The idea is to not using a switching regulation or lm317 regulation direct regulator


What are the fault tolerances on the FDA food handling guidelines?

Sometimes I have suggested that food that sat out a little longer than optimal may be safe to eat.    Granted, this is based on my experience, and I always qualify that it shouldn't be served to guests (and by extension, customers) and that one should determine their own tolerance to risk, but I want to know if there is information as to the methodology of the FDA guidelines.  Specifically, what is the contamination rate at n hours, and what are the initial conditions of the food and environment?  How much risk is there REALLY (in incidences per n-population and such) in a standard kitchen for food that has sat out 50%, 100%, 200%, etc. longer than recommended?


What is the command that shows your computer's personal IP address? I have tried   ip addr show   But that shows much more than I want to see.


I always wondered why the hassle creating the Matrix anyway?  Yes, the machines need energy which can be harvested in the form of biological energy from humans. But why did they not just take animals, e.g. sheep. Since the physiology of animals and humans is very similar, they would likewise be able to generate energy. Advantageous over humans though, it would be possible to hold them captive without creating a Matrix.


How do you destroy a block using Commands?

How do I make a command block destroy some glowstone?


Return AJAX images but jQuery click doesn't work

I have 7 images in my index HTML, and then I use a jQuery function, when I click the images the function gives me images' ids.  The function looks like:  $(".imgss").click(function() {    alert($(this).attr("id"));  });   .imgss is a class that iIgive, but I select another city in my select box and I send variable to PHP and AJAX gives me result of other new images.  When the new image is downloaded, I try to click the images but jQuery doesn't work.  New images also have .imgss class.  This is my php code to create images :  print_r ("

$salonlarimi_ver[salon_isim]

");


Whats the difference between logistic regression and fractional response model?

Can anyone tell me the theory behind fractional response model, how it really works? I wonder if the logistic regression works only with binary variable {0,1}, why when conducting a GLM with quasibinomial family on fractional variable [0-1], it gave me same results in the estimates as the fractional response model?


Dimension of direct sum of vector spaces

Let $V$ and $W$ be finite dimensional vector spaces on a field $F$. Show that $\dim(V\oplus W) = \dim V +\dim W$.   My idea: let $\dim V=n$ and $\dim W=n$. So $\mathcal{A}=$ {${v_1 , v_2 ,... , v_n} $} and $\mathcal{B}=${${w_1, w_2 ,... ,w_m}$} this means $\forall v\in V$, $v=x_1 v_1 + ... +x_n v_n $ such that $x_1 , ... , x_n \in F$ . Similarly, $\forall w\in W$ , $w= y_1 w_1 + ... + y_m w_m$ such that $y_1 , ... , y_m \in F$ . I know as $V$ , $W$ have finite basis $V\oplus W$ has finite basis, I mean, $\forall (v,w)\in V\oplus W$ , $(v,w)=a_1 (v_1 ,w_1 ) + ... + a_p (v_p , w_p )$ such that  $a_1 , ... , a_p \in F$ . Let $p$ is minimum between ${m,n}$ .Beside, $\forall (v,w)\in V\oplus W$ , $(v,w)=(v,0)+(0,w)$ . So we can say, $(v,w)= x_1 (v_1 ,0) + y_1 (0,w) +...+ x_p ( v_p , 0) + y_p (0 , w_p)$.  I want to know how I have to continue to get correct proof. Also, I want to write in mathematical way. I will appreciate any help.


Is it possible to use regularization methods on the Harmonic Series?

I recently learned about summation methods when dealing with divergent series to give them a finite value. An example of this isusing Cesàro summation on Grandi's series to get 1/2. However every method I know of is unable to sum the harmonic series. Are there any summation methods that work on the harmonic series or is it provably impossible to sum this series?


Internal mechanism of normal contact force in a lift or other situations

I understand that if a lift is accelerating downward (suppose at 2 $m/s^2$) then a man on the lift will feel a smaller normal reaction force so the resultant force is downward so the man can match the acceleration of the floor of the lift.  Also, if suppose a rope with tension $T$ was pulling up a block from the ground then also the normal reaction force falls. As $R=mg-T$ where $R$ is the normal reaction force.   Now, my question is how exactly does this happen at a microscopic level, like involving the repulsion of electrons between two surfaces. How does acceleration/movement of the surfaces cause the electron repulsion to change or some other way cause the normal reaction force to increase or decrease?  I believe it’s not a duplicate any question as they still does not answer how the repulsion works in an accelerated frame like for the floor of the lift accelerating downwards and the man’s feet.


Newtonian mechanics in higher dimensions

Once in a book ( I think title was Mathematical Physics, no idea who the author was) saw the proof of instability of planetary orbits in 4 dimensions, cant remember the details of derivations only the final conclusion of the result. Been trying to do something similar myself, but still with no success, how ever pondered if there is any reading material that shows for dimensions higher than 3 the orbits become unstable. I remember there were problems that were easier to solve for general cases than the low specific ones. So maybe there is a simple trick that would take care of that problem. My question is are there any higher dimensions were the orbits remain stable? Is this a mathematical curiosity or was there any body knowledge in physics that considered such cases but ultimately came to conclusion that there is nothing worth pursuing in these lines of thinking?


Integer solutions to $\frac{1}{a} + \frac{1}{b} = \frac{1}{12}$.

$$\frac{1}{a} + \frac{1}{b} = \frac{1}{12}$$  I'm trying to find all integer solutions to this equation. I've played with this equation algebraically to see if I can figure out the restrictions on $a$ and $b$. For example, I know at least one of them must be divisible by $12$ because  $$   a + b = \frac{ab}{12}  $$  I'm wondering if there are more general approaches.


Will taking a gap year after my Master's degree improve or degrade my potential of doing a PhD?

I am starting a Master's conversion course (in Computing and IT Management) but I am still very unsure about all of the details about doing a PhD such as where and what I want to do it in. Some programs require that you have you Master's certificate to hand when applying too, and I haven't even started my MSc yet.  I was thinking of taking a gap year after the MSc to continue my entrepreneurial activities and goals, to find some temp/contractual work and to give myself more time to apply to PhD applications.  Would this be beneficial or detrimental to my applications and academic prospects?


I have the command grep public -A 5 in Unix which prints the trailing 5 lines after the string public.  I need to do the same in Windows using command prompt. How do I do it?


Let $R$ a left artinian ring. Show that if $a \in R$ is not a right zero divisor, then $a$ is a unit in $R$.  Comments: I am tryed to do so: See the R-module $_{R}R$ and consider the function $f: _{R}R \longrightarrow _{R}R$ defined by $f(r)= ra$. As $R$ is artinian then $_{R}R$ has a composition series. I do not know if it's out there the way.


Anything that converts GUI actions to commands to be sent to remote ubuntu via SSH?

Is there anything that would allow me to run a GUI on client side of SSH(ie on windows)& that would convert the GUI actions made to corresponding commands to be sent via SSH client(in my case putty) to remote ubuntu server ? Also it could show me the corresponding commands that it sends via SSH. I dont have GUI installed on my ubuntu server so I am looking out for any tools that may be installed on the client(running windows 7) that communicates to ubuntu server via SSH.  Does anything like that exists ? Or may be a tool that helps me doing frequent actions via Putty more easily than me requiring to remember exactly how to accurately write all the ubuntu commands ?


How can I find the right lens cap for my lens?

I own a Nikon D3000 Camera with the AF-S 18-55mm VR Kit Lens. Last week I lost the lens cap and now I want to buy a new one.  But when I went to , I got confused with the different ranges of lens names —  LC-62, LC-78, etc.  My concern is what if I order one lens cap and it won't fit correctly on my lens?  If you guys have an D3000, can you please let me know how to find the correct lens cap names?


Does the Otyugh's Tentacle attack allow a saving throw to avoid being grappled if the attack hits?

Per the Monster Manual's statblock for the Otyugh (pg 248), a successful tentacle attack results in the following:     If the target is Medium or smaller, it is grappled (escape DC13) and   restrained until the grapple ends.   Does the target get a chance to do a save of some kind to avoid being grappled in the first place? I am aware that the target can use an action to escape after being grappled, but is there any way a Medium or smaller creature can avoid being grappled on a successful hit with a tentacle attack?


My application for a short visit visa to the UK was refused because of insufficient cash in my bank account on 21/06/2018. However, I have some saving certificates which were redeemed on 17/06/2018, increasing my account threefold.  How long should I wait before reapplying, as long as I will provide bank statements supporting that this money was already in my account in form of saving certificates and not a form of funds parking?


Find $\lim_{n\to \infty} \int_n^{n+1} {\sin x \over x}  dx$   I thought about defining $\space F(x) = \int_0^x {\sin t \over t}  dt \space$ and then the limit is $\space \lim_{n\to \infty} (F(n+1) - F(n))$, so the answer is 0? It doesn't seem ok


SharePoint 2013 Change default start time and end time on calendar event

We're scheduling a lot of similar events, so the start time is almost always 8:30AM and the end time is almost always 5:30PM (not necessarily on the same day). Is there any way that we can set the defaults for these through JavaScript? It doesn't necessarily have to be JS, we just can't use workflows to solve this problem because we do occasionally have events that need to happen at other times. A solution editing the NewForm.aspx would work as well if anyone has that. OOTB would be even better.  It looks like this () was written for SP2010. I used Firebug to inspect the labels for my time fields. They aren't actually "label" tags, they are "nobr" tags and do not have "for" attributes, so it appears that this solution is trying to access elements that SharePoint is no longer using.   I would just use the ID columns of the time boxes themselves, but they are some kind of generated code and and I'm worried that they won't always be the same. I have shown the generated code for the Start Time select box:  <select id="ctl00_ctl41_g_05eee1e1_a7d0_4b5e_9eb1_dc1e566ce47e_ctl00_ctl05_ctl00_ctl00_ctl00_ctl04_ctl00_ctl00_DateTimeField_DateTimeFieldDateHours" dir="ltr" name="ctl00$ctl41$g_05eee1e1_a7d0_4b5e_9eb1_dc1e566ce47e$ctl00$ctl05$ctl00$ctl00$ctl00$ctl04$ctl00$ctl00$DateTimeField$DateTimeFieldDateHours">     <option value="12 AM">12 AM</option>     <option value="1 AM">1 AM</option>     <option value="2 AM">2 AM</option>     ...     <option value="11 AM">11 AM</option>     <option value="12 PM" selected="selected">12 PM</option>     <option value="1 PM">1 PM</option>     ...     <option value="10 PM">10 PM</option>     <option value="11 PM">11 PM</option> </select>   I need a way to set this that will always work and I suppose that if we know that the ID will always be the horrendously long string shown above, then I can just hard code that and get the element by its ID, but I don't know if it will be. Any advice?   Also, if it is important, I am using the modal window (and need to continue to do so).  EDIT: This question was flagged as a duplicate. In order to argue why this should not be the case, I would like to first point out, that the link I referenced above, is the same link as the answer to the question this one was claimed to be a duplicate of. Furthermore, I covered why I don't believe the solutions work. Yes, it is essentially the same goal, but the previous question was in the context of SharePoint 2010 and this one is in the context of SharePoint 2013 and I believe that makes them different because the answers for SharePoint 2010 don't appear to work for 2013. Also, the answers to the other question specifically exclude modal dialogues which are required in this question.


UPDATE if exists else INSERT in SQL Server 2008

I want to know how can I use UPSERT or in other words UPDATE if records exists Else enter new record operation in SQL Server using one statement?  This example shows the ways of achieving this in Oracle  But it uses Dual table for it which doesn't exists in SQL Server.  So, Any SQL Server Alternatives (No Stored procedures) please ?


How can I find out which authors cite a certain author X most often?  This question is different from  because here I ask about the number of citations (a very specific metric), whereas the other question and answer are about other metrics.  (Regarding background research I tried as required by : I checked  but a solution isn't obvious. Maybe following id_scholarcitedby there could work. Also,  provides similar info (weighted influence as estimated by AI etc), but that does not perfectly correlate with the number of citations.)


Find two matrices $\mathbf{A}\in\mathbb{C}^{2\times2}$ and $\mathbf{B}\in\mathbb{C}^{2\times2}$ such that:   they have the same eigenvalues  but they are NOT similar   MY ATTEMPT  The characteristic polynomial of $\mathbf{A}$ is $p_{\mathbf{A}}(\lambda)=\lambda^{2}-\mathrm{tr}(\mathbf{A})+\mathrm{det}(\mathbf{A})$ and the characteristic polynomial of $\mathbf{B}$ is $p_{\mathbf{B}}(\lambda)=\lambda^{2}-\mathrm{tr}(\mathbf{B})+\mathrm{det}(\mathbf{B})$.   "The same eigenvalues" $\Longleftrightarrow P_{\mathbf{A}}(\lambda)=P_{\mathbf{B}}(\lambda)\Longleftrightarrow$ $\Longleftrightarrow\begin{cases} \begin{array}{c} \mathrm{tr}(\mathbf{A})=\mathrm{tr}(\mathbf{B})\\ \mathrm{det}(\mathbf{A})=\mathrm{det}(\mathbf{B}) \end{array} & \Longleftrightarrow\end{cases}\begin{cases} \begin{array}{c} a_{11}+a_{22}=b_{11}+b_{22}\\ a_{11}a_{22}-a_{21}a_{12}=b_{11}b_{22}-b_{21}b_{12} \end{array}\end{cases}$  And now?


Fourier transform standard practice for physics

I'm very confused about the definition of the inverse Fourier transform between time and frequency spaces. In many places, including , the Fourier transform pairs are defined by:  \begin{align} f(t)=&\int_{-\infty}^\infty\tilde{f}(\omega)e^{i\omega t}\frac{d\omega}{2\pi} \\ \tilde{f}(\omega)=&\int_{-\infty}^\infty f(t)e^{-i\omega t}dt \, . \end{align}  In other sources, such as "Many-body quantum theory in condensed matter physics" by Bruus and Flensberg, or , they are instead defined by:  \begin{align} f(t)=&\int_{-\infty}^{\infty}\tilde{f}(\omega)e^{-i\omega t}\frac{d\omega}{2\pi} \\ \tilde{f}(\omega)=&\int_{-\infty}^\infty f(t)e^{i\omega t}dt \, . \end{align}  Why are there these two different definitions? I thought maybe they mean the same thing, but this would only seem to be the case for $\tilde{f}(\omega)=\tilde{f}(-\omega)$ and I don't see why this should be true in general.  Indeed, I originally noticed this discrepancy when I tried to calculate the impedance of a capacitor using the second definition above, and obtained: $$Z=-\frac{1}{i\omega C} \, ,$$ and when I looked up the solution, found that it is generally accepted to be: $$Z=\frac{1}{i\omega C} \, ,$$ which is what I obtain using the second definition above. I don't understand how these two functions could have the same physical interpretation. That's why I asked here instead of the math stackexchange, because I'm sure they can be defined either way formally, but it seems like if we want to think physically about time and frequency, one must be correct.  Can anybody tell me which one is correct, or explain why they are equivalent?


Can some please explain to me this code   def zap():     print stype  def main():     if True:         stype="something"         zap()          else:         stype="something else"  if __name__ == '__main__':     main()   stype is already defined before I called zap function  But I'm getting this error.  Traceback (most recent call last):   File "C:\Users\x126\Desktop\ss.py", line 12, in <module>     main()   File "C:\Users\x126\Desktop\ss.py", line 7, in main     zap()   File "C:\Users\x126\Desktop\ss.py", line 2, in zap     print stype NameError: global name 'stype' is not defined


Checking that a decimal number is in a range in bc

I've written this if, that is obviously not working, and I still can't manage to get over it:  #LASTEFFECTIVEHASH if (( $(echo "$LASTEFFECTIVEHASHMINVAL < $LASTEFFECTIVEHASH < $LASTEFFECTIVEHASHMAXVAL" | $BC -l) )); then                 echo "$DATESTAMP - LASTEFFECTIVEHASH=$LASTEFFECTIVEHASH is between $LASTEFFECTIVEHASHMINVAL and $LASTEFFECTIVEHASHMAXVAL"|tee -a $LOGFILE else                 echo "$DATESTAMP - LASTEFFECTIVEHASH=$LASTEFFECTIVEHASH is not between $LASTEFFECTIVEHASHMINVAL and $LASTEFFECTIVEHASHMAXVAL"|tee -a $MSGFILE $LOGFILE fi   But, when value are out of ranges, it results in this:  20170810003646 - LASTEFFECTIVEHASH=139.2 is between 104.9 and 136.9   I'm following the maths syntax: if x > 104.9 and < 136.9, in maths you write it 104.9 < x < 136.9. But I suspect that bash/bc are behaving differently from my math's teacher.  It would be great if bc won't fail to count up to 137 ;)


I have a point $(X,Y)$ on an elliptical curve $E(a,b)$ where $a=-3$ and $B$ is a large number that is in hexadecimal from -51BD. To compress this point oficially in a program, we know that every $X$ on the curve has two $Y$'s, one even and one odd. Therefore, we only need to store whether the corresponding $Y$ point we are storing is even or odd. So to store the point $(X,Y)$ now, we shift $X$ ridding of its most significant bit and add $1$ if the $Y$ point is odd. Therefore, one can think of the compressed point being $2 \cdot X+B$ ($B$ is the bit we added to tell if $Y$ was odd or even) since the multiplication by $2$ is implied because of the shift. I understand this completely. It's recovering the original point that has me confused.  Since a point on the curve is given by the equation $y^2=x^3+ax+b$, we can find square roots officially in $\mathrm{GF}(p)$. The following from my spec is what confuses me.  If $p$ is prime and congruent to $3$ mod $4$, one of its square roots is $z^{(p+1)/4} \bmod p$ and the other is $p-z^{(p+1)/4} \bmod p$. How would I solve this? What is $z$?  For example, I know how to extract the $x$ point so let's say I simplify the right side of the equation to be $7$ and $p$ is $11$. Would I be trying to solve for the square root that's equal to $7$ mod $11$?


Better explanation of the common general relativity illustration (stretched sheet of fabric)

I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general relativity there is this one illustration, which is being used over and over (image from Wikipedia):    I always thought that general relativity gives another way how you can describe gravity. However for this illustration to work, there needs to be another force, pulling the object down (referring to a direction in the attached image). If I put two non-moving objects in the image, what force will pull them together?  So where is my understanding incorrect? Or is general relativity not about explaining gravity and just describes how heavy objects bends spacetime (in that case the analogy is being used not correctly in my opinion)?    UPDATE Thank you for the answers and comments. Namely the XKCD comics is a spot on. I understand that the analogy with bent sheet of fabric pretty bad, but it seems that it can be fixed if you don't bent the fabric, but just distort the drawn grid.   Would you be so kind and answer the second part of the question as well - whether general relativity is explaining gravitational force. To me it seems that it is not (bending of spacetime simply can not affect two non-moving objects). However most of the time it is being presented that it does.


How can you prove this set theory statement by contradiction

$$f(A\cup B)=f(A)\cup f(B)$$  My attempt:  Suppose that $f(A\cup B) \neq f(A) \cup f(B)$, then $f(A\cup B)$ has a variable $x$ that is neither in $A$ nor $B$; however, $A\cup B$ implies that $x$ must me in either $A$ or $B$, thus we have a contradiction.  Yeah... it's terrible, but I have no intuition as to how to prove this in any other way. Also, the proofs I saw in the lectures were sometimes as unconvincing as this one I just came up with.  It's like they're saying this is this because it is so. How do you develop the skills and intuition to solve these kind of problems?  Also, you have to know it is true before proving it. How do you even know it is true just by looking at it?


How does "${2:-}" work in an 'if-then-else example' below?  Somehow I cannot help but think that being ${2:-} it means the second argument, but I am curious what the colon(:) and dash(-) after the digit 2 mean?    if [ "${2:-}" = "Y" ]; then      prompt="Y/n"      default=Y   elif [ "${2:-}" = "N" ]; then      prompt="y/N"      default=N   else      prompt="y/n"      default=   fi    read -p "$1 [$prompt] " REPLY </dev/tty


Prove the inequality $|\mathrm e^{i\theta_1}-\mathrm e^{i\theta_2}|\le|\theta_1-\theta_2|$.

$$ |\mathrm e^{i\theta_1}-\mathrm e^{i\theta_2}|\le|\theta_1-\theta_2| $$  This seems like a simple inequality but I cannot prove it simply. Do I have to consider Taylor expansions? Could anyone help me how to prove this inequality?


Simple past or Present Perfect with “this week”

Please look at the following,      a) I finished my work this week.    This means I am either speaking at the end of the week or that I am speaking on any day of the week expecting no more work for the week. Am I right? Or are there few other scenarios? If yes, then please let me know.     b) I have finished my work this week.    Please tell me how this sentence is different from the above one? I fail to understand the difference.


How to compare two independent samples using a permutation test?

Suppose I have two independent samples. How can I test if the two samples have been drawn from the same distribution using a permutation test? The sample sizes are equal. The population distributions are unknown.


Continuous Looping animation - Differing rotational speeds

Just trying to do my first animation and am struggling to make it loop seamlessly. I think the differing rotational speeds of the 2 objects are the thing to overcome but I'm not sure how.  I basically want the earth to do one revolution to the teapot's 2 orbits around the earth.  Can anyone have a look at this  and advise me?  Thanks in advance.


What simpler mail server can I use instead of postfix?

I have a home server which needs a mail server for error messages, mostly.  I used postfix but I find the features/complexity compromises not optimal for my home server: there are tens of lines to check/configure, stunnel to install for TLS, ...  What simpler mail server with TLS support can I use, that is also packaged by Canonical? I'm going to only use an external relay server provided by my provider.


Let $T:V → V$ be a linear transformation where $V$ is finite dimensional. Show that exactly one of (i) and (ii) holds: (i) $T(v)=0$ for some $v ≠ 0$ in $V$ ; (ii) $T(x)=v$ has a solution $x$ in $V$ for every $v$ in $V$  Not sure how to answer this, I'll get any help I can get. Thanks in advance!


Why doesn't "Software Updater" update all software?

(this question is a follow-on to discussion in comment about this question: )  Ubuntu 18.04, LXDE desktop, 64 bit  Today I was notified by Software Updater that there was software to update.    I ran the updates and got this result    Then when I run aptitude, there is more to do    Why doesn't Software Updater update all software?