Commandline tool to lookup current timezone?

I have my date and time settings set to use the "automatic time zone" and that is reflected in timedatectl:   amanda@rajje:~$ timedatectl status                       Local time: Fri 2019-11-15 14:01:29 EST                   Universal time: Fri 2019-11-15 19:01:29 UTC                         RTC time: Fri 2019-11-15 19:01:29                        Time zone: America/New_York (EST, -0500)        System clock synchronized: yes systemd-timesyncd.service active: yes                  RTC in local TZ: no   But it doesn't update itself. Today I turned on my laptop, connected to a brand new coffee shop internet wifi that is definitely in California, aka America/Los_Angeles (PST, -0800) but I'm still seeing EST on my system clock. I've traveled a bunch over the last few months and my laptop consistently does not updated the timezone.   I know that at least my browser knows where I am because Google Maps defaults to the neighborhood I'm in. So the problem isn't that I'm using an internet connection that's hiding my location.   I thought that sudo systemctl restart systemd-timedated would do it, but that has no effect.  I can quickly change the time zone with timedatectl set-timezone America/New_York or timedatectl set-timezone America/Los_Angeles but I'm wondering if there's a way to use timedatectl or another tool to just tell Ubuntu to figure out what time zone I'm in. A sort of "I'm pretty sure that's wrong, could you check again?" trigger or command?


What's wrong with the "Hero Of Time" Hat?

I asked a question at UTC 2:00:16 (16 seconds past UTC 2 am), which was 7 PM in US Mountain Standard Time, but I didn't get the hat for that.    Do I need to be accurate to +/- 10 seconds or something?  Or is the hat broken?


Getting the length of the last line of paragraph w/o producing vertical space

Can I use $$\predisplaysize$$ to record the length of the last line of a paragraph without producing any output (vertical space)?  \documentclass{article} \usepackage{lipsum}  \newdimen\lastline  \begin{document} \lipsum[1]  \lipsum[2]  \lipsum[1] $$\global\lastline=\predisplaysize$$  \lipsum[2]  The last line of the third paragraph was \the\lastline\ long (minus 2em).  But how can I record it without creating a gap between the 3rd and the 4th? \end{document}


How to add vertical space after \hline without breaking vertical lines in a table

I have seen similar questions on the matter (, ) of adding vertical space and not breaking vertical lines, the solutions suggested are to add space after the \\ using \\[0.1cm] for example or changing the \arraystretch which I do not want to do. Using \\[0.1cm] allows me to add space just before a \hline but not after as well.  How can I add vertical space after a \hline without breaking vertical lines in a table?  Please find my MWE below:  \documentclass{scrreprt} \usepackage{setspace} \usepackage[left=2.5cm,right=2.5cm,top=3cm,bottom=3cm]{geometry} \usepackage{array,tabularx} \doublespacing  \begin{document} \begin{table}[htb]   \centering   \onehalfspacing   \caption{Table of info.}      \begin{tabular}{c | c c}  & C/S Analyser & O/N/H Analyser \\  & EMIA 320 V2 & EMGA 830 \\[0.1cm]    \hline    \noalign{\vskip 0.1cm} Sensitivity (ppm) & 0.1 & 0.001 \\ Furnace type & Induction & Impulse \\ Carrier gas & Pure O2 & Pure He \\[0.1cm]    \hline     \end{tabular}    \doublespacing   \label{tab:chem} \end{table} \end{document}


May we please have the SO "Easter Egg" question back?

According to  in the recently-necromanced "Jon Skeet Facts" thread:     Jon Skeet once fixed a production problem in his pajamas.   That page links to a citation - what used to be a picture of Jon Skeet in his pajamas. This was the page:    However, that page seems to be gone, which is a net loss for SO because it is referenced by other pages. There are over a thousand pages on the internet which reference that link, including the aforementioned "Jon Skeet Facts" page. Which is now gone.  May we please have this page back? Maybe transfer it to meta?  I mean, that thread has been around since the very beginning, and I was basically here in the very beginning, so I feel like a part of my upbringing has died.  How about this: since I have been a long-time SO contributor, may I please have the ability to view questions deleted by arm chair moderators? Or can you set it up so that if the referer is "google" then the page magically un-deletes so that we don't break google's search results? I hate it when google 404s.


Transfering Items to Another Account On PS4

Can you transfer items that you already bought on a PS4 account to another PS4 account? The accounts are in the same console, and I need to know how.


Extract random sample of N lines based on pattern

I have a file formatted like this:  train/t/temple/east_asia/00000025.jpg 94 train/t/temple/east_asia/00000865.jpg 94 ... train/s/swamp/00000560.jpg 92 train/s/swamp/00000935.jpg 92 .... train/m/mountain/00000428.jpg 68 train/m/mountain/00000126.jpg 68   The last number is the class number. I have 50 different classes, and each class has 1,000 lines. I would like to take a random sample of size N from each class, and store the result in another text file.


Let $R$ be a ring and let $J$ be an ideal of $R$. Assume $J$ contains   a unit of $R$. Prove $J=R$, rigorously.   Again I feel here as if the statement is intuitive so I am not able to make it rigorous. If you could show all steps in the proof that would be nice.


Display "Submit for Approval" button in the Approval History related list based on condition

I have two custom objects with master detail relationship.   My requirement is that the parent should be submitted for approval only after all its child records are submitted for approval.  For this, client has asked me to show the "Submit for approval" button in the Approval History related list only the above condition is satisfied.   I think the solution can be achieved through VF page by removing the "Submit for approval" button from the Approval History related list and showing it using the condition.  But my question is:- Is it possible to remove the "Submit for Approval" button from the Approval History related list?  Also, I should not hide the Approval history section(as a way to prevent the users from submitting for approval when criteria is not met) because users should be able to see the approval history.


Play Store icons are no longer transparent

The past few days I have noticed that the Play Store icons have a black background. I've even done a Factory Reset. I am facing the problem with every icon in the play store. Is there any way to get rid of it?


When expressing opinions : to me vs for me

What is correct?: "To me, studying is important" or " For me, studying is important"


I'm studying on my own over the summer and I'm having a bit of trouble with this question. Also, I don't have any background in this, I haven't taken any classes in this yet so, if you choose to help, please go slow. Thanks. Anyway, here is the problem:   For any set A, finite or infinite, let B be the set of all functions mapping A into the set {0,1}. Show that the cardinality of B is the same as the cardinality of P(A) (power set of A).   Here's what progress I've made. Let f be a mapping from B to P(A). Now I have to show it's injective. Let g,h be elements of B and let x be an element of A:   f(g(x)) = f(h(x))  g, h are elements of B and B maps x to {0,1}. If g(x) = h(x) = 1 or g(x) = h(x) = 0 then we are done. But what about the possibility of g(x) = 1 and h(x) = 0 or vice-versa. How do I deal with that possibility?


looking at English magazine, I found a example. Colby grew up "on" a cattle ranch in Texas. why not "in"?  ranch is a place, isn't it?


Can the human eye distinguish colors in the periphery?

In the back of my mind I have the idea that human eyes can't notice the color of objects in the far periphery, and that any subjective perception of colors is done by the brain that tries to fill in the color percept.  Is that true?


Strong Induction to prove Fibonacci Sequence property

I am to prove by induction for the fibonacci numbers $F_1 = 1$, $F_2 = 1$, $F_n = F_{n-1}+F_{n-2}$ the following $P(n)$ is true: $$\left(\forall n \in \mathbb{N}^{+}\right)\left[\left(F_{n+1}\right)^{2}-\left(F_{n+2} \cdot F_{n}\right)=(-1)^{n}\right]$$ So far, I have written and expanded out $P(n+1)$, but I cannot find where I am to use the inductive hypothesis of $P(n)$ to reach any conclusion. I start with $$P(n+1) = (F_{n+1})^2+2F_{n+1}F_n+(F_{n})^2-F_{n+2}F_n-F_{n+2}F_{n-1}-F_{n+1}F_n-F_{n+1}F_{n-1}$$ and this eventually reduces to $$F_{n+1}F_n-F_{n+2}F_{n+1}$$ with my inductive hypothesis applying for $P(n)$ and $P(n-1)$ to make some terms go away. However, as I continue with this method, I make no progress towards my goal of simplifying to $(-1)^n$. How can I make progress without simplifying this endlessly?


If $I$ is ideal, then $I$ is a subring. But, if $R$ is a subring, $R$ is not necessarily an ideal. In other words, the converse of the first statement does not always hold.  Examples of ideal in $\mathbb{Z}_6 = \{0,1,2,3,4,5\}$, where $I$ denoted an ideal:   $I = \{ \overline{0} \}$ $I = \{ \overline{0} , \overline{2} , \overline{4} \}$ $I = \{\overline{0} , \overline{3} \}$   I have two questions here:   How to find an example of a subring that is not necessarily an ideal? Are there any examples in $\mathbb{Z}$? How do we prove that $I = \{ \overline{0}, \overline{3} \}$ is an ideal of $\mathbb{Z}_6$, above?


Identify a film (and possibly book) about a scientific incident that makes most of the Earth's population disappear

This is a film that I remember seeing on television, probably in the first half of the 1990s. I recall that it may also have been a book.  Some plot elements that I recall:   The protagonist, male, wakes up in his bed, and discovers that everybody has disappeared without trace from his neighbourhood. The man works at a lab, presumably doing some scientific research. He returns to the lab. Whilst in the lab an accident happens that, although not serious, blocks his exit from the lab. He fashions an explosive device that allows him to exit. He later discovers that there are other survivors. The survivors form a search party to seek others. The protagonist disagrees with this search, but reluctantly takes part. They split up and each search a particular area. However the protagonist does not do his search; instead he is an a lab performing more scientific work into the cause of the incident. When the search leader contacts him by walkie-talkie to ask where he is, he lies, consulting a map to give a street name. The finale of the film takes place at the scientific lab where he worked, and he drives a truck at high speed into the lab. At this point another incident occurs, and he wakes up on what appears to be a different planet.   I recall being told that the film was based on a book, and had a different ending - the incident at the finale resulted in the protagonist going back in time to the first incident and re-living it.


Annoying E-Mails: Where did they get my mail-address?

Today I received a spam message with the topic of n question at Stackoverflow:     Topic: Re: chrome.identity.getAuthToken cannot get Token in Chrome   Extension      Hi Ole,      Just wondering if you ever got this question answered.  If not, maybe   a brief chat with a Javascript wizpert could help: link (Link removed)      [...]   As this seems quite focussed on my SO-Post and my Mail is private: How did they do that? What can I do to stop that in the future?


Input Decimal value isn't changing after a function is used on it (Python)

I want to change this decimal value within a function. As you can see, it changes within the function but doesn't impact the input argument outside the function when I want it to change. eg. aud = Decimal('500'). aud = Decimal('1000') def changecash(cash):     cash -= Decimal('500')     print(cash)      changecash(aud) print(aud)  The output is:  500 1000


Delete and recreate a Clash of Clans account?

I accidentally left a clan after receiving troops, and now all of the clan members won't let me re-join and they are saying on global chat: "Don't let Corry join ur clan she is a hopper and she was only in our clan for a total of three seconds!"   So I'm not too popular at the moment and I want to delete and recreate a new account. I've tried to uninstall then reinstall but it's not working. Any ideas? If it helps I didn't bind my account.


Ubuntu 17.10 freezing on suspend and won't shutdown

Hello i'm using ubuntu 17.10 on a lenovo ideapad 110s and anytime the system suspends it freezes on the lock screen and if I try to to shutdown the computer it stays on the shutdown screen. Holding down the power button is the only way I can shut it down. I've used previous versions of ubuntu on this laptop and haven't had any troubles.


Is there any point in submitting application earlier?

Do admission committees start evaluating applications before deadline? I mean is there any point in sending application before deadlines? My main concern is USA universities.


An intermediate step in a problem I was working on was to find a closed form for the sum $$\sum_{i=1}^n i2^i.$$  WolframAlpha returns $2^{n+1}(n-1) + 2$, but didn't provide any step-by-step solution.  I would usually provide progress that I made, but I wasn't sure how to proceed(although I solved the problem by bashing out small values).


Are there adjectives in English that are still adjectives when adding -ly to it?   More precisely, I mean words that would be originally adjectives, and that would still be adjectives when adding the -ly suffix to it (even if the meaning is different).   For example, elderly is, as elder can be used as an adjective. Lone is as well. Are there others?   (I have read  but it is asking about whether there are nouns that turn into adjectives (as opposed to adverbs) when you add -ly. I'm asking about whether there are adjectives that remain adjectives after adding -ly.)


I am aware of the Script Editor menu. That is not what I'm looking for.  Is there a way to run an Applescript from the menu bar? I can save it as a file and run it from the Script Editor menu, and I can save it as an application and stick it in my dock. Is there a file format that allows it to run from the menu bar, as many applications do? Or a way to edit the code that does the same thing?


What is the difference between ROC curve and Confusion matrix?

I'm confused about the ROC curve and confusion matrix. The area under the ROC curve represents the accuracy of the classifier. But the confusion matrix also shows a measure of accuracy. So which method is better for me to find the accuracy of the model?


confused on searching for specific special characters for an assignment

these are the assignment objectives i need help with Write an interface and two classes which will implements the interface.  Interface - StringVerification  will have the abstract method defined - boolean verifyInput( String input );   class EmailVerification implements StringVerification  implement the verifyInput() method in EmailVerification class. The method should validate   a    user input String,   character by character and see the input string has a dot (.) and an at the rate (@)   character in it. If any of the condition wrong the verifyInput method will return a false boolean value.  Example of a valid Email id – mail@mymail.com  class PhoneVerification implements StringVerification  implement the verifyInput() method in PhoneVerification class. The method should validate user input String, character by character and see, the input string is all digits and the phone number has exactly 10 digits. If any of the condition wrong, the verifyInput() method will return a false boolean value.    Example of a valid phone number – 5161112222 here is the code for # 1  public interface StringVerification {   boolean verifyInput( String input );    }  the code that i have for 2  public class EmailVerification implements StringVerification {   private boolean dot;  private boolean atSymbol;   public EmailVerification( ) { String at = "@"; String period = "."; dot = false; atSymbol = false;  }      public boolean verifyInput(String input) {   for ( int i = 0; i < input.length ( ); i++)  {     char c = input.charAt( i );          char at = @ ;   if ( c == at )          return true ;             }    }    }  i have yet to start 3 but i am assuming i use an if statement in a method to make sure that there are 10 digits i am not sure how to search for specific special characters without using an import


When I click the bounty info icon on the iOS app. The added bounty description and reason is not shown.  For example:


Set $E$ which halves the measure of an open interval

This was an exam question. I know that my answer is wrong, but I believe myself to be on the right track. Can someone help me finish my construction? Here is the question.  Find a set $E$ with the property that for any open interval $(a,b)$, $m(E \cap(a,b))= \frac {b-a}{2}$ or prove such a set cannot exist.  Here's what I figure so far:  1) Obviously $E$ itself is not an interval. If it was, $m(E \cap E)=m(E)/2,$ which is only true if $m(E)=0,$ so $E$ is not an interval.  2) Furthermore, $E$ does not contain any intervals. If it did, then choose $E' \subset E,$ where $E'$ is an interval. Then $m(E' \cap E)=m(E')=m(E')/2$ as before. So $E'$ is not an interval and therefore $E$ contains no intervals.  Now, during the exam, my brain jumped to a Cantor set, so I attempted to build a Fat Cantor Set based on removing $2^{k-1}$ pieces of length $\frac {1}{2^{2k}}$ from the middle of each unit interval in $\Bbb R$. I know that this set has measure $1/2$, but if $(a,b)$ is one of the intervals deleted in the construction of the cantor set, the measure of the intersection is not half the measure of the interval. There are also infinitely many unit intervals in  $\Bbb R,$ so in order to have disjointness, I'd have to be tiling $\Bbb R$ with these sets, but then clearly taking any set not centered appropriately doesn't meet the hypothesis either. So this set doesn't work as I thought it did.  In hindsight, I'm skeptical as to whether such a set actually exists. But how to prove it?  Edit: A particularly nice solution would be one that gets me from $E$ has no intervals to $E$ does not exist.


What to use?: Infinitive, bare infinitive or gerund as a complement after an expression

I came across some sentences and I was wondering which word is correct: 'train,' 'to train' or 'training'?  What we should do is train our workers to become more efficient.  All I we do is train our workers...  All you have to do is train workers...


What is the relativistic calculation of travel time to Proxima Centauri?

It has already been  how fast a probe would have to travel to reach Alpha Centauri within 60 years.  NASA has done  into a probe that would take 100 years to make the trip.  But I am interested in this question from a slightly different perspective.  I would like to know how long the trip from our solar system to Proxima Centauri would take for both a ship and for an observer on Earth while accounting for the effects of general relativity on a .  The following assumptions may be made:   The ship starts and ends at 0 km/s relative to the Earth observer. The ship experiences a constant force of acceleration of 20 g until the half-way point and then a constant force of deceleration of 20 g until the destination. The path traveled is such that accleration is in only one spatial direction. The distance traveled is 4.25 light years.   Calculate (accounting for general relativistic effects):   Time of trip for Earth-based observer. Time of trip for ship-based observer. Maximum speed.   You don't need to consider mass, or life-support systems, or method of propulsion; I am really only interested in the effects of relativity on the perceived time of the trip.


Find the center of the symmetry group $S_n$.   Attempt:  By definition, the center is $Z(S_n) = \{ a \in S_n : ag = ga \forall\  g \in S_n\}$. Then we know the identity $e$ is in $S_n$ since there is always the trivial permutation. Suppose $a$ is in $S_n$, but not equal to identity. Now we can imagine the permutation as bijective function that maps from $\{1,2,\dotsc,n\}$ to $\{1,2,\dotsc,n\}$.  So suppose $p$ is a permutation map. Then $p$ maps from a location $i$ to a location $j$. Take $p(i) = j$ where $i\neq j$. Let $k$ be in $\{1,2,\dotsc,n\}$, where $k$, $i$ and $j$ are all different elements. The cycle $r = (jk)$, then we will see if this commutes.  $rp(i) = rj$    Can someone please help me, I am stuck?  Thank you.


Travel to Bulgaria and Romania with Italian residence permit

I have looked it up and the resources all talk about schengen visa, travelling with eu national family member etc. so I would like to get a more assuring answer about my situation:   I am a non-EU national with an Italian residence permit. My father is an Italian citizen. I will be travelling to Sofia and Bucharest next month with my girlfriend who is a British citizen. Do I need to get a visa to enter these two cities?


I had set Nemo as default file manager on my Unity desktop. I want return to old configurations and Nautilus be my default file manager. How can I do that?


I need show that Brieskorn Manifold is submanifold with dimension $2n-1$ and calculate specifically for $d=2$ and $n=1$  $W(d)=\lbrace (z_{0},z_{1},...,z_{n})\in \mathbb{C}^{n+1}\vert$  $ z_{0}^{d}+z_{1}^{2}+...+z_{n}^{2}=0$ and $\vert z_{0}\vert^{2}+\vert z_{1}\vert^{2}+...+\vert z_{n}\vert^{2}=2\rbrace$  The second cuestion I don't know what it means.


Show that if $n\geq5$, then every element of $S_n$ is a product of 4-cycles.

Figured this needs to broken down case by case, where case one is whenever the permutation is even, and case two is when it is odd. Whenever a permutation is odd, then the product of that permutation with a 4-cycle is even, and so I figure we need only show this for whenever it is even.   My other way would be to show that each transposition can be written as the product of four cycles, but I'm a bit lost on this, since four-cycle is itself the product of three transpositions. This was the way to do it.


How to apply the WKB approximation in this case?

I'm trying to learn how to apply the WKB approximation. Given the following problem:      An electron, say, in the nuclear potential   $$U(r)=\begin{cases}  & -U_{0} \;\;\;\;\;\;\text{ if } r < r_{0} \\   & k/r \;\;\;\;\;\;\;\;\text{ if } r > r_{0} \end{cases}$$   1. What is the radial Schrödinger equation for the $\ell=0$ state?      2. Assuming the energy of the barrier (i.e. $k/r_{0}$) to be high, how do you use the WKB approximation to estimate the bound state energies inside the well?     For the first question, I thought the radial part of the equation of motion was the following  $$\left \{ - {\hbar^2 \over 2m r^2} {d\over dr}\left(r^2{d\over dr}\right) +{\hbar^2 \ell(\ell+1)\over 2mr^2}+V(r) \right \} R(r)=ER(r)$$  Do I simply just let $\ell=0$ and obtain the following? Which potential do I use?  $$\left \{ - {\hbar^2 \over 2m r^2} {d\over dr}\left(r^2{d\over dr}\right) +V(r) \right \} R(r)=ER(r)$$  For the other question, do I use $\int \sqrt{2m(E-V(r))}=(n+1/2)\hbar π$, where $n=0,1,2,...$ ? If so, what are the turning points? And again, which of the two potentials do I use?


I am using twitter bootstrap for a project and want to create a dropdown menu and have the list items act as a file upload but cant seem to edit it in such a way!I do not want a button in my dropdown menu nor do I want a separate button or entity that shelters the button. I want a dropdown menu where the list item acts as a file upload button and is styled as such, below is the base html code using bootstrap 3.0  <ul>     <li>         <input type="file">             <span class="glyphicon glyphicon-file">             </span>             File Upload     </li> </ul>   I know how to edit it to be a button but am not sure how to make it so it looks like a regular <li> but also act as the file input! Is this even possible?


How do I track voting activity on my meta.[sitename].stackexchange posts?

Meta sites (with the exception of meta.stackexchange.com) do not alter reputation.  Thus I do not get any sort of alert when my posts are upvoted or downvoted.  How do I track or receive notifications for voting activity on meta.[sitename].stackexchange posts?


How can I color the header, section, and subsection name according to the current section value?

I'm trying to make a document with multiple "themes." This involves changing the color of the headers, section names, and headers based on what the current section is. The colors I want to use are custom colors.  Now, I know how to make this the same for the whole document, but I was trying to find a way that would automatically change it automatically depending on the current section value. I thought that it would be really easy with the ifthen package, as it seemed to be made for this (I could see if the section was equal to a value). However, it did not go as expected. I have a MWE below. Here I changed only the subsection name for clarity. I tried to make the subsections of Section One red and the subsections of Section Two blue. However, it seems like everything is blue. I did something similar for the header, but didn't go anywhere. Could anyone kindly point me in the right direction with this?  \documentclass[twoside]{article}  % For blind text \usepackage[english]{babel} \usepackage{blindtext}  % Here begins my attempt \usepackage{ifthen} \usepackage{titlesec} % Coloring the section names (didn't mess with this, but I am using this as the basis of coloring the section and subsection names) \titleformat{\section}{\LARGE\normalfont\center\color{blue}}{\thesection}{1em}{} % My attempted ifthenelse statement. I put the if, then, and else arguments on different lines for clarity \ifthenelse {\equal{\thesection}{Section One}} {\titleformat{\subsection}{\Large\normalfont\color{red}}{\thesubsection}{1em}{}} {\titleformat{\subsection}{\Large\normalfont\color{blue}}{\thesubsection}{1em}{}} % Sections begin on new page \newcommand{\sectionbreak}{\clearpage}  % For headers \usepackage{fancyhdr} \pagestyle{fancy} \fancyhf{} \fancyhead[OR]{{\textsc{\leftmark}}\quad\quad\thepage} \fancyhead[EL]{\thepage\quad\quad{\textsc{\leftmark}}} \renewcommand{\sectionmark}[1]{\markboth{#1}{}}  % For colors \usepackage[usenames,dvipsnames,svgnames,table]{xcolor}  \begin{document}  \section{Section One}  \subsection{Subsection One} \blindtext[5]  \subsection{Subsection Two} \blindtext[5]  \section{Section Two}  \subsection{Subsection One} \blindtext[5]  \subsection{Subsection Two} \blindtext[5]  \end{document}


Segmented Display With SMD Pads? (Not Thru-Hole or Half-hole SMD)

I'm looking through a product design, and I've seen these SMD / sticky segmented displays LCD being used.    They are not hand-soldered, the segmented display appears to use some conductive sticky pad that attaches the pads on the board that have the common & signals going to the LCD.  Do you know what this is called specifically?  I've used typical thru-hole segmented displays, and I see that you can get like half-hole module type displays.  Anyone know the term of display that you just stick on the board?   (The white part is actually the backlight, and then the LCD display just goes on top and connects to those rectangular vertical pads circled in red).


How does the flags remaining count equation work?   How many I've got per day? The number of flags remaining depends on my actives, declined, helpfuls, what else?


Let $1 \leq p < q < \infty$. Show that if $x=(a_k)∈ℓ^p$  i.e. the condition that the series $$\sum_{k=1}^\infty|a_k|^p$$ converges holds, then $x∈ℓ^q$  i.e. $$\sum_{k=1}^\infty|a_k|^q$$  converges.  I did try to use the ratio test but I don't think it will work because of the power on the terms in the series.


I'm trying to restore some files for a friend who messed up a USB stick by pulling it out of the computer too soon. By searching invisible partitions I was able to restore the files. All files are intact, except 1 excel file that seems to be corrupted.  I've googled about ways to repair an Excel file, because the default repair options in Excel 2003-2010 do not work for this file. I've came across a numerous  third-party apps, of which the  one seemes to be able to do the job: Recovery Toolbox for Excel.  Of-course, this and all other apps I found require a purchase to actually repair the file. It seems a bit silly to pay 30 dollars for a one time thing, and something that is not for myself. So, I would like to keep that as a last-resort option.  Is there anything I can try to fix this? I've attached a screenshot of how the file looks when I open it on my OSX when converted to a HTML file (to view the code), for  the option that it could be a character set problem.


I would like my [a,o,i,e] to appear correctly if I type the letter after an '.  Right now, I get an accent character as shown in the subject. Is there any way to turn this off?


How do I deal with an HP laptop with lost power-on password?

My neighbor has asked me help with his laptop, an HP with lost power-on password. I tried inserting an Ubuntu cd to format the partition, but well... it doesn't even get there. Any ideas?


Why is feed-forward mechanism used in hash functions?

The compression function of SHA-1 when used in Davies-Meyer mode adds its input to the chaining values at the final step. For the first message block, the IV is used as the input and in the next step, the previous block's output (as specified by Merkle-Damgård) is used. These values are fed to the last round of the compression function.  Why would removing the feed-forward part (i.e.,the final step where the input value is added to the result to get the final output) make the hash function insecure? Apart from the fact that the compression function would not satisfy desired randomness properties (being a permutation for each fixed message).


Here is our students/Here are our students

Which is correct:   Here is our students. Here are our students.   Thanks.


Use syntax highlighting for cat .gitignore

Is it possible to get syntax highlighting for .gitignore files when using cat?  Update:  Tried sudo apt-get install python-pygments as suggested by @rovo but when using comments in the .gitignore it stops working.  Sample .gitignore (does not work):  # JetBrains IDEs .idea   Sample .gitignore (works):  .idea


RAW, can you break up turns between a rider and their controlled mount?

Can't seem to find clarification on this, it always just directs me to the Mounted Combat rule.  Mounted Combat [...] The initiative of a controlled mount changes to match yours when you mount it. It moves as you direct it, and it has only three action options: Dash, Disengage, and Dodge. A controlled mount can move and act even on the turn that you mount it. [...]  Rules as written, can a rider attack, have the mount take the Disengage action and move, and make another attack on the same turn?


Why is the momentum of a particle $\gamma mv$?

I am very new to relativity, and as I was going through Resnick & Halliday, I saw that momentum was no longer $mv$, rather $\gamma mv$. This was the proof:     $$p =  mv = m \frac{\delta x}{\delta t_0}  $$   where $\delta t_0$ is the proper infinitesimal time interval to cover $\delta x$ distance.     Using the time dilation formula, $\delta t = \gamma \delta t_0$ we can then write    $$ p = m \frac{\delta x}{\delta t_0} = m \frac{\delta x}{\delta t} \frac{\delta t}{\delta t_0} = \gamma m \frac{\delta x}{\delta t} $$   However, since $ \frac{\delta x}{\delta t} $ is just the [observed] particle velocity,    $$ p = \gamma mv $$   On the other hand, when I went on to Feynmann's book I saw that there he talked about using "the new m" (the relativistic mass) to derive all the equations and said      $$p = mv = \frac{m_0 v}{(1 - \frac{v^2}{c^2})} = \gamma m_0 v $$   My problem is that if both these proofs are true, then why doesn't one consider the other's argument, id est, why aren't both of these factors considered together ? If the mass is really changing, why doesn't Resnick & Halliday account for it? That way the momentum would turn out to be $p = \gamma^2 mv$  Am I missing something here?


Will closing a credit card with an annual fee affect my credit score?

I am 20, and just opened an airlines credit card in order to save a lot of money on plane tickets. My credit score is currently 728, but I know that does not mean much because of the relatively short credit history I have. For the past year I have been using a single credit card to make purchases and I always pay off the entire balance before the due date. Recently, I saw a great offer to save money on plane tickets by opening an airlines credit card. The annual fee is $99, but the savings is far greater than the annual fee. I'd like to pay off the price of the tickets, and the annual fee as soon as I get my first statement, and then cancel the credit card. I know I am not going to use it again, because I rarely fly so I can't justify spending $99 a year. How will this affect my credit score?  From research I've done online, it sounds like there is minimal impact of closing a card if I do not owe anything on any cards. Is this true? I will definitely have a $0 balance on my other card when I close the new airlines card.   FURTHER EXPLANATION: My question does not match the "duplicate" question, because I am not looking for how my credit may be impacted by keeping the card open, nor am I talking about closing a card that has been open for a long period of time. The card will be a month old, or slightly older, when I close it.


$E=mc^2$ what is unique about the speed of light?

What unique property of light, makes it the conversion factor between energy and mass? It has to be more than a coincidence that the speed of light, just happens to be the correct number number to convert mass to energy


Prove that the fundamental group of the circle is non-trivial if the fundamental group of a space $X$ is non-trivial

Prove that if $\pi_1(X,x_0)\neq 1$ for some topological space $X$, then $\pi_1(S^1,1)\neq 1$   I don't quite know how to proceed with this. I know that any path $f:I\to X$ has to factor through $S^1$. I was trying to map non-homotopic paths in $X$, say $f$ and $g$, to $S^1$, and then showing that they're homotopic in $S^1$, and hence must be in $X$. However, I don't know how to map paths from $X$ to $S^1$.  Am I even on the right track? Any help will be greatly appreciated


Where does the 'Natural Language' rule come from?

Frequently it is said (sometimes by me) that 5e's rules expect the reader to use 'natural language' or the 'normal' meaning of words when interpreting any words in the rules texts the game doesn't specifically define.  Where does this idea come from?  If it is a rule, where is it found?


What is the difference between TeX and LaTeX?

I know LaTeX and I've heard that LaTeX is a set of macros in TeX. But what does it exactly mean?


OpenVPN not default gateway for all traffic

I'm trying to make my client forward all traffic through a VPS running OpenVPN. As you can see, it will allow pings to both domains and raw IP addresses, but it will not allow traffic like that made through curl and traceroute doesn't come up with anything. The traffic works correctly when not connected to the VPN.   All information is here:   Thank you.  Working configs thanks to solution below:  Server:  port <integer> proto udp dev tun ca ca.crt cert vpnserver.crt key vpnserver.key  # This file should be kept secret dh dh4096.pem tls-auth ta.key 0 server 10.8.0.0 255.255.255.0 ifconfig-pool-persist ipp.txt push "redirect-gateway autolocal" push "dhcp-option DNS 8.8.8.8" push "dhcp-option DNS 8.8.4.4" keepalive 10 120 cipher AES-256-CBC comp-lzo user nobody group nogroup persist-key persist-tun status openvpn-status.log verb 3   Client:  client dev tun proto udp remote x.x.x.x <port number> resolv-retry infinite nobind persist-key persist-tun ca ca.crt cert vpnclient.crt key vpnclient.key tls-auth ta.key 1 ns-cert-type server cipher AES-256-CBC comp-lzo verb 3


Can I use Westvale Abbey in a Commander deck that does not use black?

Is it possible for me to use  in a Commander deck that does not use black? I am making a Blue, Green, and White commander deck, and I would like to add Westvale Abbey. Could I use it?


Does visiting Canada from USA under ESTA reset the visa waiver?

I'm staying in the US under the Visa Waiver Program at the moment, until 8th March. I'm planning to visit Montreal, Canada, for a week and then come back to the States.  Is a new visa waiver required to come back to the States or is the old one still valid after leaving the country?


implementing a singly-linked-list containing one integer and the reference to the next element. I wrote 2 methods which display the entire list.   VERSION A does contain the local variable current.  VERSION B does not contain a "current" variable. Both versions work fine, I however dont understand why VERSION B without a local variable works too.  public class LList{  // VERSION A public static void printListA(Node Head){     Node current = Head;       while(current != null){         System.out.println(current._value);         current = current._next;     }     }     // VERSION B public static void printListB(Node Head){       while(Head != null){         System.out.println(Head._value);         Head = Head._next;     }   }  Question to Version B: Since a Node-instance qualifies as a mutable object, it is passed by reference to the "printListB-function". I would therefore expect the Head-node to be changed by "printListB", since "Head" is over-written at each iteration ("Head" should become the Tail-node). This is however not the case, and it seems that "Head" is treated like a variable local to the function.  Could somebody explain, why printListB does not change the Parameter "Head" despite it being passed by reference.  Thanks a lot in advance.


ShareLatex font type in a beamer presentation

Is there an easy way to change the font type in ShareLatex? I've tried all of the instructions I could find on their website, but they do nothing.  Let's say, for example, that I wanted to use Windows font Arial in a beamer presentation. How would you do this?


Can I travel from USA to Cuba as an European citizen?

Me and my girlfriend would like to go to Cuba from Denmark. We would like to go to Miami for a few days before going to Cuba and then spend the rest of the vacation in Cuba. So our flights are as follows:  Denmark-Miami  Miami-Havana  Havana-Denmark  My question is, if this is legal? I have read something about new regulation and that you can not go to Cuba from the USA as a tourist. But it is not easy to figure out, so du any of you know the answer to this?


The following MWE displays the problem.  \documentclass{beamer}  \begin{document}  \begin{frame}{Frame 1}     \def\test{hello}     \test % prints hello \end{frame}  \begin{frame}{Frame 2}     \test % should print hello, but doesn't \end{frame}  \begin{frame}{Frame 3}     \def\test{something new}     \test % prints something new  \end{frame}  \begin{frame}{Frame 4}     \test % should print something new  \end{frame}  \end{document}   I am using \def simply because it came as part of an answer I found elsewhere on this site. It seems that the macro \test is only defined within the scope of the environment (in this case frame so perhaps the problem isn't beamer dependent). How can I have the command \test defined globally (from this point on)?


Ubuntu installation freeze from USB (Gigabyte P15)

I just got a new laptop (a Gigabyte P15 with FreeDos pre-installed) but I want to install Ubuntu (16.04).  I prepared my USB key with Rufus and the Ubuntu 16.04 .iso. It went well.  Now, I boot on the USB from the new laptop and get stuck with the Ubuntu logo (and the little dots under it). Nothing else happens. For hours. (I tried several times). The dots don't change colors like they ususally do.  I tried to set boot mode in UEFI and Legacy OS: it didn't help. In UEFI mode, I also tried to run the option "Try Ubuntu" (without installing it). I got stuck on the same screen with the Ubuntu logo.  What can I try ?  Thanks


Why is it "obvious" that: $$2^0+2^1+2^2+...+2^n=2^{n+1}-1$$  And how about: $$2^{-1}+2^{-2}+2^{-3}+...+2^{-n}=1-2^{-n}$$  I am looking for some intuition about these facts.  Is there a similar pattern when the base is $3$?


Are unilateral closures aligned with the spirit of this community?

Most of the times, when I see a question being closed, two cases arise:   The question was closed by Community moderator (perhaps it was a dupe). The question was closed by 5 VtC's, and names of the voters are displayed.   Most of the times I see this in Stack Overflow, which is the most active site in the whole ecosystem.  What I noticed is the following: There is at least one site when questions are being closed unilaterally. This means that one moderator vote made the question be closed.  I expect that action be taken, say, when a blatantly aggressive behavior from the OP is taken, say:   Anything violating directly or indirectly the ToS or any manifestation of common sense (e.g.: direct aggression against a user or social group, SPAM, an attempt to exploit an XSS bug, ...), which will involve even harder sanctions than closure/deletion. A blatantly off-topic question (e.g. I go to Stack Overflow to ask about how to take care of two Trachemys Scripta turtles).   The question was not blatantly off-topic (edit although it was marked as off-topic since lately every site uses that reason as a wildcard) on the site or had any strange behavior, however was put on hold unilaterally. Regarding to me, one of my questions was closed in programmers.SE (say) for similar reasons but by five users, as most of the times occurs. And closing a question with five votes looks the usual to me. I always perceived this ecosystem was led by community, and not an administrator. This means: it was self-managed with downvotes and closures are agreed by multilateral parties.  I don't want to name the site, which had the particularly annoying case -to me-, because perhaps what I think is a wrong behavior is actually right and expected under certain conditions.  Edit  which:   Follows the good subjective guidelines (mainly because it asks about facts). Had a lot of upvotes, meaning the users found the question useful and even the answers were considered useful. They are about the game industry (which is one of the topics listed as allowed in the Help Center). But... It was closed by a single admin vote.   So tl;dr: What bothers me is that there are cases where I see closures by just one user (the administrator) instead of community consensus. Perhaps there's a reason for me to be wrong about this concern. Question: What am I missing here?


How best to include programming source code in LaTeX documents?

Possible Duplicate:          I'm relatively new to LaTeX, and am starting to use it for academic paper writing. I'm doing a lot of computer programming as part of my academic work, so need to be able to include code extracts easily.  I know I can easily make them appear in a monospaced font, but what would you suggest for getting automatic syntax highlighting?


Implementing 1000BASE-T (Twisted pair) over PCB backplane

Problem:  We are designing a small payload which will contain several ethernet capable devices connected via a backplane we must design.   All guidelines concern the scenario where the PHY is connected to an RJ45 connector, but in my case I am connecting ethernet accross a backplane.  The Major Components in payload enclosure:   Embedded Gigabit Switch (Example: ) (includes Ethernet  Magnetics) 2x Embedded Computer & Expansion module (Example: (includes Ethernet Magnetics)  Interface Board to connect to enclosure connectors. Industrial connectors with/ twisted cables) Backplane connecting all the above boards   Note: Both the computers and the switch have integrated magnetic and are designed for 1000BASE-T so implementing 1000BASE-KX is not really an option.  I realize that 1000BASE-KX is made for back-plane connection but the PHY transceiver needs to be modified to support that (and magnetic removed)  Usual PCB PHY to RJ45 Guidelines:  The usual guidlines are for PCB routing between the transceiver (PHY) and the magnetic, some common ones listed below:   Signal after magnetics should be above chassis ground plane, no overlap with board ground plane. Signal should be routed as differential pairs (100Ohms controlled impedance) The use of vias is to be minimized. If vias are used, keep them to a minimum and always match vias so the differential pairs are balanced. ideally the magnetics are included in RJ45 connectors or that the RJ45 connector is very close to the magnetics.   Example Guideline Documents   (Section 5)      Similar Questions:      Answer: Small PCB section, wont have much effect, follow general layout guidelines.      Answer: Implement backplane ethernet (1000BASE-KX)      Answer: If the correct reference plane is under the signals the PHY<->Magnetics or Magnetics<->RJ45 then longer length can be run, else keep as short as possible.      Answer: Use capacitors and implement 1000BASE-KX.  Questions:   From all of the above my take home message is that I can successfully connect my different devices directly via back-plane using 1000BASE-T as long as I have the separate ground below each signal and the traces are of controlled impedance, is this correct?    If the above is correct, The impedance controlled trace on the backplane will be run above a ground plane which is only capacitively coupled to the center tap of the magnetic at each end? I guess this is the equivalent of the shielding in shielded cables? Does anyone have a link to a document/guideline describing how 1000BASE-T can be implemented on backplanes?


I was wondering if someone could help me out.  I have a function that imports a CSV into an array, but i need to remove the first line with the  My CSV is formatted like so:  lat,lng,id -34.837834,1387457,2   and so on, you get the ID  My function looks like this  private function getArrayFromCsv($file,$delimiter) {       if (($handle = fopen($file, "r")) !== FALSE) {           $i = 0;          while (($lineArray = fgetcsv($handle, 4000, $delimiter)) !== FALSE) {               for ($j=0; $j<count($lineArray); $j++) {                   $dataArray[$i][$j] = $lineArray[$j];               }               $i++;           }           fclose($handle);       }       return $dataArray;   }   The array that is outputted is as follows:  Array (     [0] => Array         (             [0] => lat             [1] => lng             [2] => id         )      [1] => Array         (             [0] => -34.837834             [1] => 1387457             [2] => 2   and so on .....  How do i go about removing the array that shows the lat,lng,id and start from the next line in the CSV?  Cheers,


Stack Exchange™ MultiCollider SuperDropdown™ image wacked

And if I click on it...        Looks like a CSS sprite issue...  I'm thinking that the image was recently changed, by looking at the name,   Currently on Chrome Version 33.0.1750.154 m. Firefox is fine though, with all zoom levels.  Steps to reproduce:  Either browse the site on a device with Retina display, or using Chrome follow those steps:   Change zoom level to 150% or more. Reload the page.


Consider two points A and B on a pipe at the same height. Fluid is in a steady flow inside.  External pressure is provided at point A and the fluid travels to point B.  The region at point A has a smaller cross section that point B. Therefore, $v_A > v_B $. As,  $ P_A + 1/2 \rho v_A^2 = P_B + 1/2 \rho v_B^2 $  Thus, naturally, pressure at region A is lower than B.   The question is how then is the fluid travelling from A to B when the pressure difference is actually in  opposite direction and flow should be reverse?


I know $4p^4+1$ can't be square number, cause $4p^4<4p^4+1<4p^4+4p^2+1$ for all natural number p. But I don't know the way to prove $3p^4-3p^2+1$ can(not) be square number. Is there a well known way to prove it?


Using value from same row in Field Calculator of QGIS

I am using QGIS. I have an attributetable with several columns. I want to change the values of column1 if they are NULL with the values of the same row in column5. case WHEN column1 is NULL THEN  END  How do I say "use the value from the same row"?


Is there a way to insert a blank line between two equations in align environment?  From what I understand a blank line is interpreted as \par and \par is not allowed in align. Can I disable this "feature" in align environment?  Reason:  I like my code to be in 80 column format. So when I hit M-q (fill-paragraph) without blank lines, the code looks like this:  \begin{align}   \min \sum_{k \in K} \sum_{(i,j) \in A} c_{ij} x_{ij}^k + \sum_{(i,j)     \in A} f_{ij} y_{ij} \\ \sum_{j \in V_i^+} x_{ij}^k - \sum_{j \in     V_i^-} x_{ji}^k = \begin{cases} d^k & \text{si } i = O(k) \\ -d^k     & \text{si } i = D(k) \\ 0 & \text{sinon} \end{cases} & \quad   \quad \forall i \in V, \; \forall k \in K \\ \sum_{k \in K} x_{ij}^k   \le u_{ij} y_{ij} & \quad \quad \forall (i,j) \in A \end{align}   instead of this:  \begin{align}   \min \sum_{k \in K} \sum_{(i,j) \in A} c_{ij} x_{ij}^k + \sum_{(i,j)     \in A} f_{ij} y_{ij} \\    \sum_{j \in V_i^+} x_{ij}^k - \sum_{j \in V_i^-} x_{ji}^k   = \begin{cases} d^k & \text{si } i = O(k) \\ -d^k & \text{si } i =     D(k) \\ 0 & \text{sinon} \end{cases} & \quad \quad \forall i \in   V, \; \forall k \in K \\    \sum_{k \in K} x_{ij}^k \le u_{ij} y_{ij} & \quad \quad \forall   (i,j) \in A \end{align}   which is easier (for me) to read and edit.


I've updated the Bios but I still get an error when installing Ubuntu

For days now I've been trying to install Ubuntu along side windows 10 on my Dell laptop but failing. I was getting an errata error telling me to update the microcode. So after reading a few solutions I managed to update the Bios to the latest version. I also partitioned one of my hard drives (F) and allocated over 70GB. However I'm still failing to install Ubuntu alongside windows using a bootable USB stick. When I boot my machine from the USB, the process kind of starts but brings an error saying I need to update microcode, it then automatically skips that an continues to the next page where I'm to select to install or try Ubuntu. I click install, it goes ahead but when it reaches the menu where I should select "install along windows", that option isn't available. Instead I have like 3 options; Install Ubuntu and erase windows; and other options but doesn't give me the option to install along windows. Please help. How do I do about this?


I have an upcoming statistics exam and I'm studying it on my own. I was recommended Hogg's Introduction to Mathematical Statistics, but I didn't find it helpful. I just want a book which covers basic mathematical statistics and statistical inference: stochastic convergence, estimation of parameters, testing hypothesis, etc. all at an elementary level (suitable for a math undergraduate), with good introduction to the required background for such concepts. Can you provide me a good source?


Prove one case of the Reverse Triangle Inequality $|x-y|≥|x|-|y|$ for all reals $x$ and $y$

Prove this inequality for all reals $x$ and $y$:  $$|x-y|≥|x|-|y|$$


Calculate $S =\displaystyle\sum_{k=1}^n\frac {1}{k(k+1)(k+2)}$. This sequence is neither arithmetic nor geometric. How can you solve this. Thanks!


Is `echo $TEST` expanding an asterisk in the variable a bug?

Is this a Bash bug?  $ mkdir test && cd test && echo "a" > "some.file" test$ echo '*' * test$ TEST=$(echo '*') test$ echo $TEST some.file   Why is the second output the resolution of * into (all) filenames instead of just a literal * output? Looks like a bug in Bash?  Tried on Ubuntu 18.04, bash version 4.4.19(1)-release. Expect it will be the same on other OS'es.


Showing that the following metric space is complete

Q) Let $\mu(X)<\infty$ and $V$ be the space of all measurable functions on $X$. Let $V_0 = \{f\in V| f=0, \mu \text{ -a.e. }\}$ and   $$d(f,g)= \int_X\frac{|f-g|}{1+|f-g|}d\mu$$  Show that $V/V_0$ is a complete metric space.  I've shown that $d$ is a metric but to show that $V/V_0$ is complete, I have to show that every Cauchy sequence converges to a limit in $V/V_0$ in metric $d$ but am not sure how to show that?


I am travelling to Paris and Italy for tourist purpose. My itinerary will be Mumbai -> Paris -> Italy -> Paris -> Mumbai.  So my question is if I have single Entry Visa, would be Ok to enter in Paris again?


Recommended resources for starter in quantum computing and its eventual applications on machine learning

A growing interest in Quantum Computing -particularly in its eventual applications on Machine Learning- has taken over me and I would like to follow that path. I have strong Maths (Calculus, Multivariate Calculus, Linear Algebra, Math. Analysis, etc) and Probability foundations but my knowledge in Physics is rather poor. I also have some knowledge in common Machine Learning. What subjects should I study and -if possible- what books per subject could I try? I will probably do this on my own but I don't mind taking rigourous books if it's needed. Thanks a lot, I know the answer to my question is a large one and I appreciate the effort it will take to approach it.


Science fiction novel about two girls raised with dolphins

Read in late 1960's, early 1970's. Fiction about 2 teenage girls raised with dolphins who could breathe under water. Brother (or uncle/guardian) brought them on land, to teach about being human.


I'm looking for a noun from English folklore.  It should describe a place where unusual, mysterious, possibly magical, occurrences happen.  The locals shun and avoid this place. Its influence might be beneficial sometimes, but it's unpredictable - only the desperate, mad, or naive would seek it.  I suppose archaisms and obscure words should be fine.  I need it for a translation of a fantasy game.  The Polish noun I'm looking to translate is "uroczysko" - in case some of the answerers know Polish.  The sites in question aren't one-of-a-kind so unique names starting with capital letters, like Shangri-La or Xanadu, won't do.


Given that a series {$x_t$} where $x_t=\sin(t+U)$, $U$ has uniform distrubution on $(0,2\pi)$. Is {$x_t$} second-order stationary? I know here we need to show $E(x_t)$ is constant and $cov(x_{t+s},x_{t})$ only depends on $s$. Now $E(U)=\pi$, $\mathrm{Var}(U)=\frac{\pi^2}{3}$. My problem is how to find the expection value and covariance of $\sin$ function? Indeed $\mathrm{Cov}(x_{t+s},x_{t})$ = $E(x_{t+s}x_{t})-E(x_{t+s})E(x_{t})$, so the probelm is expected value.. Here I think it is hard to find the p.d.f of this $\sin$ function. Can anyone help me with that? Thank you in advance!


Is WUBI freely available? I checked the link to download WUBI and the only way to proceed is by giving some amount as donation. I will surely do it, but I don't have a Paypal account and I am in urgent need to install Ubuntu. Can someone help me?


How to show that $\Bbb Z[x,y,z,w]/(xw-zy)$ is not a UFD

I am trying to show that $R=\Bbb Z[x,y,z,w]/(xw-zy)$ is not a UFD.    Let $I=(xw-zy)$.  Let $X=x+I$, $Y=y+I$, $Z=z+I$, and $W=w+I$. My guess is that $X$ is irreducible and therefore $(X)$ is a prime ideal. Now, $XW=ZY$, so that $ZY\in(X)$. I want to show that $Z,Y\notin(X)$ and conclude that $R$ is not a UFD.  However, I cannot confirm my guess because I don't even know how $R$ looks like and how to find an argument to show $X$ is irreducible. I think it suffices to prove that $X$ is irreducible. If it is so, the argument can be applied to $Y$, $Z$, and $W$. Therefore, $Z,Y\notin(X)$.  Any help?


I was wondering how hard it would be to enable a 'hiding' option that let me hide certain questions that I don't want to see. That way if it was a very active question that I have no interest in, I could simply click hide and not see it anymore.  The only foreseeable reason why this couldn't be implemented completely with a Greasemonkey script is that it would be nice to get replacement posts. As of right now, even the hide tag feature simply hides the questions after they were loaded. If I hid a lot of tags, I would end up getting very few questions on the home page.  This is, of course, due to caching.


I have 2 main categories:   Software  Hardware   Each of these categories has 10 subcategories for example hardware: cpu/graphic/hard disk and...  Which URL is better for SEO?   www.example.com/hardware/this-is-content.html or www.example.com/cpu/this-is-content.html


Passing destructured kwargs not working python

I have a function that needs to be called and needs to pass the kwargs to another function after performing some logic, but this is'nt working, can someone please guide me where i am going wrong? My code is: def a(**kwargs):    #perform some logic and then call function c using the kwargs    c(kwargs)  def main:    a(a=1,b=2,c=3)  How should I succesfully forward these params to function c


Nginx redirect users to another domain based on Client IP address

I'm trying to redirect some users to another website based on their client IP address. For example if user is in range 192.168.0.0/24 they'd be redirected to another website.  I've found  article which mentions this method:  server {    if ($remote_addr = 1.2.3.4) {   ## Also will it work with subnet address like 192.168.0.0/24?       rewrite ^ http://www.yourwebsite.com/otherpage.htm;    } }   I guess it would work fine. But how can I supply IP range list file into this if block? Including hundreds of IP address in single line wouldn't look good.


Evaluate $\lim\limits \frac{x-\sin\sin\cdots\sin x}{x^3}.$

Problem  Evaluate $$\lim\limits_{x \to 0} \frac{x-\sin\sin\cdots\sin x}{x^3},$$where $\sin\sin\cdots\sin x$ denotes n-fold composite sine function.  Solution  Consider applying Taylor's Formula with 3-order at $x=0$. We may obtain $$f_n(x)=\sin\sin\cdots\sin x=x-\frac{n}{6}x^3+\mathcal{O}(x^3).\tag{*}$$ To prove this, we can apply the mathematical induction. Let $n=1,$ then $$f(x)=\sin x=x-\frac{1}{6}x^3+\mathcal{O}(x^3),$$  It's true and shows that $(*)$ holds for $n=1$. Assume that $(*)$ holds for $n=k$. Then $$\begin{align*}f_{k+1}(x)&=\sin(f_k(x))\\&=x-\frac{k}{6}x^3+\mathcal{O}(x^3)-\frac{1}{6}\left(x-\frac{k}{6}x^3+\mathcal{O}(x^3)\right)^3+\mathcal{O}(x^3)\\&=x-\frac{k+1}{6}x^3+\mathcal{O}(x^3)\end{align*}.$$ This shows that $(*)$ holds for $n=k+1$. As a result, $(*)$ holds for all $n=1,2,\cdots.$ Now,let's go back to deal with the problem. $$\lim\limits_{x \to 0} \frac{x-\sin\sin\cdots\sin x}{x^3}=\lim\limits_{x \to 0} \dfrac{x-\left(x-\dfrac{n}{6}x^3+\mathcal{O}(x^3)\right)}{x^3}=\frac{n}{6}.$$  Please correct me if I'm wrong. Hope to see other solutions. Thanks.


Separable $\Rightarrow$ Lindelöf for metric spaces without using second-countability

It is well-known that for metric spaces, being separable, strongly Lindelöf and second-countable are equivalent. I know how to prove the equivalence between separable and second-countable, and I guess I could prove the equivalence between being second-countable and strongly Lindelöf. Moreover, I can prove that if a metric space is Lindelöf, then it is separable. But I don't know how to prove the converse without proving that it is second-countable first.  Do you know a proof like that? If there is some, do we need some kind of Choice?


Problem on displaying not maximized windows

I use Ubuntu 14.04. Recently, probably after last update, I encounter with a problem when OS shows not maximized windows, popup notes or right click menu. I upload two screen shots:  1- When I moved cursor above browser tab:   2- When GIMP window is not maximized:   How I can solve this problem?


How to give vertical space for a multiline title?

\documentclass[a4paper,12pt,numbers=noenddot]{scrartcl} \usepackage{titling} \usepackage[T1]{fontenc} \title{Validation of Numerical Simulation of Fender Tests\par} \begin{document} \begin{titlepage} \begin{center} \vspace*{3cm} \textsf{\huge{\thetitle}} \end{center} \end{document}   Output     I want some more spacing between the first line and second line of my title. I tried adding \vspace, \\, \newline after the word 'Beer' but nothing works.


In "get married," etc., is "married" a verb or an adjective?

I am not sure how to explain these phrases to a nonspeaker of English. Have all these examples the same form?  Get (v) married (v past participle)   or it is Get(v) married (adj)  ? Get (v) engaged (v past participle)                   engaged (adj)  ?   Get (v) divorced (v past participle)                  divorced (adj) ? Get (v) promoted (v past participle)                  promoted (adj) ?   Could somebody help me?


Constructing automata for regular languages

I have two languages:   $\{a^n b^m \mid n, m > 0, n - m = 0 \pmod 3\}$ $\{a^n b^m \mid n, m > 0, n + m = 0 \pmod 3\}$   and I'm having trouble drawing automata for them.  For the first language, I know that the first valid pairs are ab | aabb | aaaab | aaabbb, but I'm having trouble drawing that and putting it into a general automaton.  I know the for the second language, S ← abb|aab|aaabbb are the first valid pairs, but I again don't know how to put it into a general automaton.  q1:


If I define $ I.J=\{ij : i \in I $ & $  j \in J \} $. Then prove that it is not necessrily an ideal, where $I,J$ are ideals in a ring $R$.  I have found one counter example in $R[x,y,z]$ for $I=<x,y>$ & $J=<x,z>$ & $R$ is commutative ring without unity.  But can anyone give me any other simple example. Roughly speaking observe what we have show that is $ i_1j_1 + i_2j_2 \neq i_0j_0 $.


Python multidimensional list - all values in a column changes if one value is changed

I'm trying to create a multidimensional list from a loop, but something is making all the column values change simultaneously when entering a new value for a row and column causing only the last value to be preserved. I know it has something to do with how i initialize the list, but am unsure on how to fix it.  code:  sellorderprices = ["Sellorderprice", 0, 1, 2, 3, 4, 5] buyorderprices=["Buyorderprice", 10, 11, 21, 31, 41, 51] days=["Days",150, 120, 90, 60, 30, 0] export_data=[[None]*3]*(len(days))  for n in range (0, len(export_data)):         export_data[n][0]=days[n]         export_data[n][1]=buyorderprices[n]         export_data[n][2]=sellorderprices[n] print(export_data)   this prints [[0, 51, 5], [0, 51, 5], [0, 51, 5], [0, 51, 5], [0, 51, 5], [0, 51, 5], [0, 51, 5]]


Two explorers land on a planet where the atmosphere makes their childhood terrors into reality. They try to leave the planet, but since their vessel contains the atmosphere from the planet, their hallucinations persist. The only way to defeat the hallucinations was to use the same methods that worked when they were kids. I read this before 1990, in a short story magazine.


Regex to match URL, ends up matching URL plus closing brackets when URL is between brackets

I am using the following regex to match URLs within text   new RegExp(`(https?://\\S+\\.\\S+)\\s`, 'ig');  The problem is when URL appear within brackets like this  (e.g. https://hello.com/fridaysforfuture-eu-socialmedia)  It picks off the closing bracket as part of the URL  My expected behavior is to include Closing bracket in the match if URL is like  https://hello.com/name-(1)  but exclude closing bracket if URL is within brackets like this   (e.g. https://hello.com/fridaysforfuture-eu-socialmedia)


A mathematician who wants to learn particle physics

I am a grad student in pure math, wrapping up a thesis in Lie theory. After years of talking to mathematicians and physicists, I've decided that it's time to get some formal training in physics, particularly in particle physics.  I have no formal training in physics. We're talking only a childish understanding of basic mechanics and bits and pieces of relativity and CFT, I have seen Maxwell's equations once or twice, etc. But I know Riemannian/pseudo-Riemannian geometry, the representation theory of compact and semi-simple Lie groups, some PDE, and so forth. So hopefully the math shouldn't be an issue.  With so little physics training (and hence little physical intuition!) what kind of books do you guys recommend?


Divisibility of repdigits - Prove that 99 divides even copies of 9 only

Let A(n) be a repdigit containing n copies of 9. E.g. A(2) = 99.  Prove that n must be even for A(2) to divide A(n).  As such, if Bn is n copies of x. For what values of n will B(2) divide B(n)?    I have solved the problem by showing that 11|A(n) for even n (and clearly 9|A(n) for all n). However, I would like an alternative solution, as well as to generalise the solution for other repdigits.


Expected distance between two points inside unit circle

Question: What is the expected distance between two points inside a unit circle?    I know the expected distance on the unit circle is $\dfrac 4\pi$.  The expected distance $E$ must equal the integral $$E=\frac1{\pi^2} I=\frac1{\pi^2}\iint_{x^2+y^2\le 1}\iint_{z^2+w^2\le 1} \sqrt{(x-w)^2+(y-z)^2}\,\mathrm d x\,\mathrm d y\,\mathrm d z\,\mathrm d w.$$  Someone gives the beautiful answer $E=\dfrac1{\pi^2}I=\dfrac{128}{45\pi}$.  Polar coordinates seems complicated here. Any ideas to simplify the integral?


I'm running ubuntu on a raspberry pi 4 (8GB) and I cannot for the life of me get it to update because I think it can't find 91.189.91.38 80 for some reason even though I can go there through my browser just fine. I've been trying to fix this for ages. But 90% of the posts are super old and don't work and some people mention some things with a router but don't say what needs to be done and it's driving me nuts. ubuntu@ubuntu:~$ sudo apt-get update && sudo apt-get upgrade Ign:1 http://ports.ubuntu.com/ubuntu-ports trusty InRelease Hit:2 https://download.mono-project.com/repo/ubuntu stable-focal InRelease Get:3 http://ports.ubuntu.com/ubuntu-ports trusty-updates InRelease [65.9 kB] Get:4 http://ports.ubuntu.com/ubuntu-ports trusty-security InRelease [65.9 kB] Get:5 http://ports.ubuntu.com/ubuntu-ports focal InRelease [265 kB] Get:6 http://ports.ubuntu.com/ubuntu-ports trusty Release [58.5 kB] Get:7 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main Sources [431 kB] Get:8 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main i386 Packages [1089 kB] Ign:8 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main i386 Packages Get:10 http://ports.ubuntu.com/ubuntu-ports trusty Release.gpg [933 B] Get:8 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main i386 Packages [1355 kB] Get:8 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main i386 Packages [1355 kB] Ign:8 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main i386 Packages Ign:13 http://ports.ubuntu.com/ubuntu-ports trusty-security/main i386 Packages Err:8 http://ports.ubuntu.com/ubuntu-ports trusty-updates/main i386 Packages   404  Not Found [IP: 91.189.91.38 80] Ign:13 http://ports.ubuntu.com/ubuntu-ports trusty-security/main i386 Packages Err:13 http://ports.ubuntu.com/ubuntu-ports trusty-security/main i386 Packages   404  Not Found [IP: 91.189.91.38 80] Get:14 http://ports.ubuntu.com/ubuntu-ports focal/universe arm64 Packages [8458 kB] Get:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages [4642 kB] Get:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages [4642 kB] Get:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages [4642 kB] Ign:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages Ign:19 http://ports.ubuntu.com/ubuntu-ports trusty/main i386 Packages Ign:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages Ign:19 http://ports.ubuntu.com/ubuntu-ports trusty/main i386 Packages Ign:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages Err:19 http://ports.ubuntu.com/ubuntu-ports trusty/main i386 Packages   404  Not Found [IP: 91.189.91.38 80] Ign:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages Ign:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages Err:15 http://ports.ubuntu.com/ubuntu-ports focal/universe i386 Packages   404  Not Found [IP: 91.189.91.38 80] Fetched 456 kB in 7s (63.4 kB/s)                                                Reading package lists... Done N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'https://download.mono-project.com/repo/ubuntu stable-focal InRelease' doesn't support architecture 'i386' E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/trusty-updates/main/binary-i386/Packages  404  Not Found [IP: 91.189.91.38 80] E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/trusty-security/main/binary-i386/Packages  404  Not Found [IP: 91.189.91.38 80] E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/focal/universe/binary-i386/Packages  404  Not Found [IP: 91.189.91.38 80] E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/trusty/main/binary-i386/Packages  404  Not Found [IP: 91.189.91.38 80] E: Some index files failed to download. They have been ignored, or old ones used instead.


Trace of the product of two matrices and singular values

How can I prove that: $\operatorname{trace}(A^\top B) > \sum_i -\sigma_i(A)\sigma_i(B) $


Importing a shapefile and keep getting error with PostGIS manager

I am new to PostGIS and using pgAdmin. I have tried to import a shapefile into PostGIS manager and it gives me this message:  Importing with configuration: ex_hzfi99mczhvqbnkrya6ryz35mveyt_osm_point, public, geom, C:\Users\rhiem\Desktop\Database file\Slovenia\ex_hzfi99McZHVQbNkryA6Ryz35mveYt_osm_point.shp, mode=c, dump=1, simple=0, geography=0, index=1, shape=1, srid=0 Shapefile type: Point PostGIS type: POINT[2] Unable to convert data value to UTF-8 (iconv reports "Invalid argument"). Current encoding is "UTF-8". Try "LATIN1" (Western European), or one of the values described at http://www.postgresql.org/docs/current/static/multibyte.html.  Shapefile import failed.


Hi I am writing for a book. Header screen should be as follows.    \documentclass[12pt]{book}  \usepackage[top=25mm,bottom=25mm,left=25mm,right=25mm]{geometry}  \usepackage[all]{background} \usepackage{amsthm} \usepackage{afterpage} \usepackage{xcolor} \definecolor{myaqua}{rgb}{1,1,1} \definecolor{myaqua1}{rgb}{0,0.5,0.45} \usepackage{fancyhdr} \usepackage{ptext,xcolor} \usepackage{showframe}  \usepackage{tikz} \usetikzlibrary{calc}   \usepackage{changepage} \strictpagecheck   \usepackage{fancyhdr} \fancyhf{} \fancyhead[LO,RE]{\thepage} \fancyhead[LE]{عنوان کتاب} \fancyhead[RO]{\leftmark} \renewcommand{\headrulewidth}{0pt} \pagestyle{fancy}   \usepackage{xepersian} \settextfont[Scale=1.2]{Yas}  \linespread{1.5}  \newcommand*{\vsp}{2cm} \newcommand*{\hsp}{2.5cm}  \newcommand{\MyTikzLogo}{%  \begin{tikzpicture}[remember picture,overlay] \checkoddpage \ifoddpage     \draw  [color=magenta,line width=2mm] ($(\paperwidth+\hsp,-\vsp)$) --($(\hsp,-\vsp)$); \else     \draw  [color=cyan,line width=1mm] ($(0,-\vsp)$) --($(\paperwidth-\hsp,-\vsp)$); \fi  \end{tikzpicture} }  \SetBgContents{\MyTikzLogo} \SetBgPosition{current page.north west} \SetBgOpacity{1.0} \SetBgAngle{0.0} \SetBgScale{1.0} \makeatletter %\renewcommand \thechapter {\@tartibi\c@chapter} \def\@makechapterhead#1{%     \vspace*{250\p@}%     {\parindent \z@ \if@RTL\raggedleft\else\raggedright\fi \normalfont         \ifnum \c@secnumdepth >\m@ne         \if@mainmatter         \huge\bfseries \@chapapp\space \thechapter         \par\nobreak         \vskip100\p@         \fi         \fi             \interlinepenalty\@M         \Huge \bfseries #1\par\nobreak         \vskip 10\p@ }} \makeatother \begin{document}  \chapter{عنوان فصل} %\pagecolor{myaqua1}\afterpage{\nopagecolor} \pagecolor{myaqua1}\afterpage{\nopagecolor} \newpage \pagecolor{myaqua}\afterpage{\nopagecolor} \section{عنوان بخش}  %\ptext[1-40] \begin{tikzpicture}[remember picture,overlay] \checkoddpage \ifoddpage \draw  [color=magenta,line width=2mm] ($(\paperwidth+\hsp,-\vsp)$) --($(\hsp,-\vsp)$); \else \draw  [color=cyan,line width=1mm] ($(0,-\vsp)$) --($(\paperwidth-\hsp,-\vsp)$);  \fi \end{tikzpicture}   \end{document}


Polarization vectors of massive and massless particles

I read from Mandl & Shaw that when quantizing massless vector particles such as photons in Lorentz gauge, there are 4 linearly independent polarization vectors (2 of them being able to "gauged away"), while when quantizing massive vector particles such as W bosons, there are only 3 linearly independent space-like polarization vectors. It also says that when W and Z gauge bosons "eat" the Goldstone bosons from Higgs field, they become massive and acquire longitudinal polarization. So apparently there is some rule that says massive vector particles have longitudinal polarization, while massless particles don't. Why is that? From what principle is it derived? Their Euler-Lagrangian equations are essentially the same (both look like Klein-Gordon equation), just one of them has $m=0$. Is it the case that when $m=0$, it has four linearly-independent solutions while only three when $m\neq0$ ?


If the Sun's temperature is around 5000K to 6000K which means it is a yellow star, why does it appear white in space?

If the thermal radiation of stars is close to the thermal radiation of a black body the sun should appear yellow but yet it appears white because of emitting all of visible wavelengths which combine into white but this is inconsistent with the classification of star colors with respect to their temperatures.


I am beginning to learn Django and get this data related "slug":  A short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs. For example, in a typical blog entry URL:  the last bit (spring) is the slug.  Why do we need this and how to use?


Will Windows 10 Technical Preview be upgradable to final release?

Is there any information about if Windows 10 Technical Preview will then be upgradable to the final release ?  I'm asking that because I would like to use it on my primary PC (I'm aware of the risks but I accept them), in place of Windows 8.1 But I'd like to avoid to reinstall all after the release of the final version.


Finding CDF of $|X-Y|$ when $X,Y$ are independent $U[0,1]$ variables

Let $X$ and $Y$ be independent variables, uniformly distributed in the interval $[0,1]$. Find the CDF of $|X-Y|$.   I tried the following:  $$P(|X-Y|\le z) = P((X-Y)\le z) + P((X-Y)\le -z) = 1 - P((X-Y)> z) + P((X-Y)\le -z).$$  Comparing with solution, it seems I have something extra. (I got $1-(1-z)^2)+...$ (not figured out what $P((X-Y)\le -z)$ is yet ). What have I done wrong?


How to export Linux command history to a file with the command logs

I need to export all commands and the commands' log of a user in a Linux distribution like Debian. Any idea?


System.out.println((a+c)==(b+d)); why this statement returning false?

import java.io.*;      public class StringTest{         public static void main(String[] args){              String a="Hello";             String b="Hello";              String c=new String("Hello");             String d=new String("Hello");              System.out.println(a+c);               System.out.println(b+d);               System.out.println((a+c)==(b+d));         }     }   Why this System.out.println((a+c)==(b+d));  statement returning false?


How much speedup does a hyper thread give? (in theory)

I'm wondering what the theoretical speedup is from hyper threaded CPUs. Assuming 100% parallelization, and 0 communication - two CPUs would give a speedup of 2. What about hyper threaded CPU?


How do I properly do shadowless product photos?

My friend asked me to create a photo like this:    I noticed that its shadowless and my first question is whether it was setup to be shadowless, or was it made shadowless in post? How many lights are involved here? I think there's one for the background, and one above the product pointing something like 30 degrees down, and then some reflectors to the side. Just guessing.   I did some Googling and came across . How could that be shadowless? Looks like the product is a few feet above the ground, which is a white seamless background, and the camera and all the lighting are all pointing down. How could there be no shadow on the ground?  Thanks!


How can I modify the list of Applications under 'Open With...'?

I recently went to open an audio file, and wanted to open it in an editor instead of a player. I right-clicked it, hovered over 'Open With...' and was met with a very unsightly list.    I have seen a problem in the past where apps will have previous versions stuck in the /Applications folder with their version number appended, but that is not the case here. Despite the duplicity in this list, no app is duplicated in /Applications nor anywhere else I can find on my system.  What causes this list to become filled with duplicates, and how can I remove them and ensure only the latest (and functional) version is list?


Background  We are proving that two free groups on sets $S_1,S_2$ are isomorphic iff the sets have the same cardinality. If they are finite, it's easy to show, by the freeness of the groups, that $2^{|S_1|}=2^{|S_2|}$, and thus the cardinalities are the same. Otherwise the power sets are in bijection, which is shown in the same way.  The problem is that in the infinite case, I'm not sure how to prove that bijection of power sets implies bijection of sets. I tried by contradiction, but only got stuck with one p.s. being in bijection with a proper subset of the other and not being able to rule out that this proper subset be in bijection with the whole p.s.  Question  Is it true that if the power sets of two sets are in bijection, then the two sets also are? If so, how do I prove it? Otherwise, can you provide a  counterexample? And if this does not hold how do I complete the proof in the background section?


Prove the Total Mechanical Energy of the System is Conserved via Differential Equations

Consider the dynamics of a particle P shown:  Newton's second law states that: $$\frac{d}{dt}(m\dot r) = \mathbf F$$  where, $\boldsymbol{r}$ is the position vector of the particle, $\boldsymbol{\dot r}$  is its velocity vector and $m$ is its mass. $\mathbf F$ is the total external force (vector) acting on P. Prove the following result regarding the existent of mechanical energy integral of motion of the system:  Theorem: For the dynamical system, if $F = -\nabla V (\boldsymbol{r}) $ i.e the force, $\mathbf F$, is the negative gradient of a scalar function $V(\mathbf r)$ of only the position vector, then the total mechanical energy of the system is conserved. Moreover, the function $V(\mathbf r)$ is nothing but the potential energy of the system.  Hints:  The above theorem states that if  $F = -\nabla V (\boldsymbol{r}) $ then the mechanical energy is an integral of motion.  The gradient of a scalar function, $V$ is written as:  $\nabla V = \partial V / \partial \boldsymbol{r} $  Also, the gradient of a scalar quantity is a vector. Do not worry about writing it in terms of the components  Recall the mechanical energy is the sum of KE and PE. Mechanical energy is given by the standard form:  $$T=1/2 ∗ m\boldsymbol{\dot r} \cdot \boldsymbol{\dot r} $$  where $\boldsymbol{\dot r} \cdot \boldsymbol{\dot r}$ represents the dot product of $\boldsymbol{\dot r} $, which is the velocity vector, with itself (i.e. square of the speed: $\boldsymbol{\dot r} \cdot \boldsymbol{\dot r} = v^2$ )  Also, let $G = G(\mathbf r, t)$  be a scalar function of a vector, $r$, and a scalar, $t$. Then, the total derivative of $G$ is related to its partial derivatives by:  $$dG = \frac{\partial G}{ \boldsymbol{\partial r}}\cdot d\mathbf r + \frac{\partial G}{\partial t}\cdot dt$$  with $\frac{\partial G}{ \boldsymbol{\partial r}} $  identified as the gradient of G, which is a vector quantity, and $\frac{\partial G}{ \boldsymbol{\partial r}}\cdot d\mathbf r $  as the dot product between the gradient of $G$ and $d\boldsymbol{r}$  Do not assume that $V(\boldsymbol{r})$ is the potential energy as this should be a natural conclusion of the analysis.  To begin, take the time derivative of the kinetic energy. Recall that if $c = \boldsymbol{a} \cdot \boldsymbol{b} $ is the dot product of two vectors, then the time derivative of c is: $$\dot c = \boldsymbol{\dot a} \cdot \boldsymbol{b} + \boldsymbol{a} \cdot \boldsymbol{\dot b}$$  ASSUME THE PARTICLE'S MASS, $m$ is constant  Edit: Attempted solution: $$\frac {d}{dt}(m \dot r) = F $$ $$\frac {d}{dr}(m \dot r)\frac {dr}{dt} = F$$ $$d(mv)v = Fdr$$ $$\int mvdv = \int Fdr$$ $$\frac {1}{2}mv^2 + \int-Fdr = C $$  Seems to prove the above theorem, however this kind of seems to ignore the fact that the variables are vectors. How can a similar approach be applied to the vectors? And still derive the potential energy at the end?  Basically, I'm asking how the potential energy can be an outcome of $$\frac {d}{dt}(\frac{1}{2} m \dot r \cdot \dot r) $$ and $$\frac{d}{dt}(m\dot r) = \mathbf F$$


Proof Assistance: Pinter Chapter 10 Exercise G5

In Pinter's "A Book of Abstract Algebra", the reader is asked to prove that the order of $a^m$ is equivalent to $\frac{{\rm lcm}(m,n)}{m}$ using the following two facts (which were proved in previous exercises):   $(a^m)^{{\rm lcm}(m,n)*\frac{1}{m}}$ = e Given that $(a^m)^t=e$, ${\rm lcm}(m,n) \leq m*t$   Side note: the order for the element $a$ in this group is equal to $n$... ( ${\rm ord}(a)=n$).  My work so far has included the following steps:  By 1. , I know that ${\rm ord}(a^m) \leq \frac{{\rm lcm}(m,n)}{m}$.  By 2. , I know that $\frac{{\rm lcm}(m,n)}{m}\leq t$  This results in the following inequality:  ${\rm ord}(a^m) \leq \frac{{\rm lcm}(m,n)}{m}\leq t$  And this is where I am stumped. I obviously need to somehow demonstrate that ${\rm ord}(a^m)$ cannot be less than $\frac{{\rm lcm}(m,n)}{m}$. However, if this is the case, I'm not  quite certain why I need the proof from 2. to help establish this.  Any suggestions?


How to save photos from iPhone to ubuntu

Okay so I want to transfer my iPhone photos to my laptop which is on ubuntu 16.04 than later transfer those photos to my new iPhone without iTunes back up so how do I do this?


Looking to achieve frame effect with shadows at corners

Where can I find PSD file or tutorial to create the effect of frame with shadow (see red arrow in image)


How to install aTube Cacher? in Ubuntu 16.04?

Is it possible to install this program in the Ubuntu operating system? What is the command line for this?


Some one is showing his conservative and little thinking by voting down all of my questions & answers on Stack Overflow. Here is the snap shot of my reputation changes:    You can also visit my profile and see this by yourself. I know the person who is doing this to me.   How can I stop them from doing this?


Drawing Hexagonal lattice with paths marked with dark black and its midedges

I am facing difficulties in drawing the following diagram in latex :-  I need to draw it in the same orientation but bold edges and mid points of my choice.


How do you teleport a certain player to spawn after they win a 1v1

I managed a KitPvP server in Minecraft and everything works fine except when players wants to duel each other. They get sent to a room where they will be dueling. The main problem is when the winner wins, I have no idea how to teleport them back to spawn.


Prove that this exponential kernel is positive definite

Let $x,y\in R^d$ and $d:R^d\times R^d \rightarrow R$ a metric on $R^d$ be given.   The exponential kernel is defined by:  $k(x,x')=e^{−αd(x,x')}$ where $α>0$.  The kernel matrix is defined as the Gram matrix of $k$: $K_{ij}=k(x_i,x_j), i,j∈[1…n]$.  Is it possible to prove that $K$ is a positive (semi-positive) definite matrix, i.e. $k$ is a positive definite Mercer kernel?


Why don't the Jedi use tutaminis instead of using their lightsabers?

(force energy absorption) allows a Jedi to catch blaster bolts and even stop lightsabers with their body using the Force:    Why don't the Jedi just use tutaminis to defend themselves instead of worrying about lightsaber combat?


A minimal example of my code is shown. The problem is, first of all, that the space between the title of the example and the description of the problem is too large. So I want to reduce the space, but I cannot figure out how. Secondly, if the example is too long it should continue on the next page, but the command allowframebreaks does not do the job.        \documentclass[10pt, ]{beamer}  \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage[T1]{fontenc}  \usepackage[framemethod=TikZ]{mdframed}  % Example enviroment \newcounter{exm}[section]\setcounter{exm}{0} \renewcommand{\theexm}{\arabic{section}.\arabic{exm}} \newenvironment{exm}[3][]{% \refstepcounter{exm}% \ifstrempty{#1}% {\mdfsetup{% frametitle={% \tikz[baseline=(current bounding box.east),outer sep=0pt] \node[anchor=east,rectangle,fill=white!100] {\strut \small{Eksempel~\theexm: #2}};}} }% {\mdfsetup{% frametitle={% %\tikz[baseline=(current bounding box.east),outer sep=0pt] %\node[anchor=east,rectangle,fill=white!100] {\strut \small{Eksempel~\theexm:~#1: #2}};}}% }% \mdfsetup{innertopmargin=0pt,linecolor=green!80,% skipabove=7pt, skipbelow=0pt, rightline=false, leftline=true, topline=false, bottomline=false, linecolor=green, innerleftmargin=5pt, innerrightmargin=5pt, innertopmargin=0pt, leftmargin=0cm, rightmargin=0cm, linewidth=3pt, innerbottommargin=0pt,% frametitleaboveskip=\dimexpr-\ht\strutbox\relax } \begin{mdframed}[]\relax% \label{exm:#3}}{\end{mdframed}}  \newcommand{\exam}[4]{% \begin{exm}{#1}{#2} \begin{small} \begin{textit} #3   \end{textit} \\[0.2cm] \textbf{Solution:} \\ #4 \end{small} \end{exm} }  \begin{document}  \section{Section Title} \begin{frame}[allowframebreaks]{Frametitle} \exam{Title of the example}{LabelName}{Descibtion of the problem...}{A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.} \end{frame}   \end{document}


Keep the same field headers after joining a table to a shapefile in QGIS

I noticed that after joining a table to a shapefile the headers of each fields in the table used for the join are changed by QGIS and they are attributed to a different name.  For instance, I had a shapefile with vegetation_codes and a table with vegetation_codes and veg_definition (these were the headers). After joining the table to the shapefile and also saving the shapefile and creating a new one, the vegetation_classes header was changed into vegetati_1.  Is there a way to keep the original headers?  I am using QGIS Dufour on Windows 7 and the table that I join to the shapefile is CSV (tried with dbf as well and the problem is the same).


get a ".ics" Outlook calendar file into Google Calendar

My office IT prevents me from saving an ics file on my computer (at least I can figure out how to do that), but i am able to email myself a calendar at my Gmail address.  I open the mail message and see the mail attachment, but I can't find any add to calendar options, or other means to get this file into Google Calendar.  My office IT also prevents download and installation of add-ons that might help. If there is something already posted that addresses this, I have missed it.  Any help would be appreciated, but again, download of additional tools is not an option.  Help?


Why and when do we need to use @autoreleasepool in ios projects

I have read so many blogs for @autorelease pool but I am still not clear about this @autorelease pool concept in objective c or ios development.  So can any one please throw a light on this concept. It would be very helpful to me if any one could provide me with an example of it and when the use of @autorelease pool is required.   How can I measure the memory allocation with use of @autorelease pool and without it.  Please throw a light on this topic might be it is duplicate.


What does mounting really mean in Linux?  And where/when can I use the mount command?  I'm new to Linux so I would appreciate a detailed answer.


Can flow of force be disturbed with technology?

I haven't seen it in movies & TV shows (And, no luck regarding novels as I haven't read any). But, in many Star Wars video games, I experience disturbance while using force in some tech environment. Is there any canonical explanation of it? I don't consider video games under canon..


I've encountered a particular type of writing occasionally and it being, derp, in writing, it's hard to tell whether there's an accent behind it. The English used seems to me to be simply incorrect, but I can't help but feel that the following features are part of a dialect or a regional style of English. One of the most glaring (and grating) features is the substitution of "saw" with "seen".  He seen him at the shop the other day. I seen that you were looking for... etc.  The use of "away (to)" is also peculiar, if not incorrect.  He was away to open the door when... He was away to get what he had asked for. etc.  I haven't come across these forms very often, and even then it was accompanied by otherwise mostly correct English, which is what makes me wonder what the hell. This is more intellectual curiosity than anything else.


How did Fred and George know what to say to open the Marauders Map?

When Fred and George give Harry the  Marauders Map, they explain how to use it. all one has to do is tap it with their wand and say "I solemnly swear that I am up to no good", and it transforms from parchment to map. to wipe it, tap it and say "Mischief Managed". but the Map had been locked up in Filches office (presumably from before the marauders left Hogwarts), and Filch didn't know how to use it (or couldn't, since he is a squib).  so how did Fred and George know how to work the map?


Been trying to get the encryption to perform the operation and store the value for each of the 4 variables, and then print each of these 4 separate variables. Where am I going wrong? encrypt only wants to work on one of the calculations.  int main(void) {    int a, b, c, d, encrypt;    printf("Enter integer 1:\n");   scanf("%d", &a);   printf("Enter integer 2:\n");   scanf("%d", &b);   printf("Enter integer 3:\n");   scanf("%d", &c);   printf("Enter integer 4:\n");   scanf("%d", &d);    encrypt = (a += 7) % 10, (b +=7) % 10, (c +=7) % 10, (d +=7) % 10;    printf("The encrypted value is: %d%d%d%d\n", encrypt);   //scanf("%d", &encrypt);    return 0; }


I applied for short stay visa for Belgium. The application status on their website is showing status "On Hold". What does this mean? Is it a bad thing?  All I am asking is what does "On Hold" mean?


Add JavaScript to NewForm sharepoint list

I create new form with info path for sharepoint 2013 list, I need to get current week from system calendar. I have javascript to do that!! but I have no idea that where is code must be add? I open list by sharepoint designer 2013. these code must be add to NewForm or Views??  Thanks for your advice


Getting "__r" relationship name from Schema.SObjectType.Fields

Say I have a master-detail relationship between two objects, Schematic__c and Part__c.  I can SOQL query the master from the detail: [SELECT Schematic__r.Name FROM Part__c]  If I'm building a query from strings, I resolve the schema name, for example in a managed package:  SObjectType.Part__c.Fields.Schematic__c.Name //gives me 'ns__Schematic__c'   But when traversing into the master object, the __r relationship suffix is what I need to surface. I've toyed around with the obvious Schema.SObjectType variations but I'm not having much luck:  SObjectType.Part__c.Fields.Schematic__r.Name //Schematic__r is not a field of ns__Symbol__c   What's the correct way to resolve the ns__Schematic__r.Name token without replacing the suffix?


I tryed to install Skype and then this  Website works fine,I rebooted but it still does not work I also imported their certificate.Is there anything I can do?  Here's the poignant part of the error:  Err https://download.01.org/gfx/ubuntu/14.04/main/ trusty/main libdrm2 i386 2.4.56-1   Failed to connect to download.01.org port 443: Mreža je izvan dosega Err https://download.01.org/gfx/ubuntu/14.04/main/ trusty/main libdrm-intel1 i386 2.4.56-1   Failed to connect to download.01.org port 443: Mreža je izvan dosega E: Failed to fetch https://download.01.org/gfx/ubuntu/14.04/main/pool/main/libd/libdrm/libdrm2_2.4.56-1_i386.deb  Failed to connect to download.01.org port 443: Mreža je izvan dosega


Delete votes shouldn't reset if OP deletes question himself

Yesterday I asked , where the issue I complained about delete votes which disappeared. It turns out that the system resets the votes if the Asker deletes and undeletes his question, which was "status by design" as  .  So I would like to request a feature where the deleted votes by others shouldn't be revoked if a user deletes and undeletes his own question; the delete votes of the users who cast before should be retained.


How many average flips to get an equal amount of H and T

Let's say the first time I flip the coin, I get HT. I would then erase the data and start over because I got an equal amount of Heads and Tails. The second attempt I get HHHTTHTT. At that point, I stop because I have an equal amount of heads and tails. I then start over. I flip the coin until I get an equal amount of heads and tails, then stop and start over. What would be the average amount of flips needed to get an even number of heads and tails? Sometimes it only takes two flips. Other times it can take many more flips. Consider the coin is fair.


To prove that $(\mathbb{P(N)},d)$ is a metric space where $\mathbb{P(N)}$ is the power set of $\mathbb{N}$.  And $d:\mathbb{P(N)}\times \mathbb{P(N)} \mapsto\mathbb{R}$ is defined by $d(A,B)=\begin{cases} 0, & \text{if A} \Delta \text{B=}\emptyset  \\ m^{-1}, & \text{where m is the smallest member of} A\Delta B \end{cases} $.   Attempt: $x \in P\Delta Q=(P-Q)\cup(Q-P) \implies x\in (P-Q) \text{ or } x\in (Q-P) $. But $(P-Q)\cap(Q-P)= \emptyset \implies x \in P \text{ and} \notin Q \text{ or }x \in Q \text{ and} \notin P. \ \ \ $    (*)  To prove the triangle inequality:  Take any three sets $A,B,C \subset \mathbb{P(N)}$ such that none of them are equal to another. Now,  $\min A \Delta B  =m_1, \min B \Delta C  =m_2,  \min A \Delta C  =m_3   $. To prove $d(A,B) \leq d(A,C)+ d(B,C)$. By (*), $m_1 \in A$ or $m_1 \in B$ but not both.   Again,  $m_2 \leq m_1$  or $m_3 \leq m_1$. Either way, we are done. When $A \neq B$ and either $B =C $ or $A=C$ (not both), we have respectively $A=C$ , $B=C$ . Which satisfies the triangle inequality. When $A=B$ it is evident.   Symmetry: We know $A \Delta B =B \Delta A$. $d(A,B)= d(B,A)$  Non-negativity and $0 \iff A=B$:   $d(A,B)=0 \iff A \Delta B= \emptyset \iff A \subset B \text{ and } B \subset A \iff A=B$. By definition $d(A,B) \geq 0$  Is this okay? Please verify.


How can I copy a vector to the end of another vector?

I have been working on what I thought would just be a simple function for quite a while now. We are expected to use push_back(), but I haven't been able to get it to work. Here's what I have right now: void append(const vector<int>& v1, vector<int> v2) {     for (int x : v1)         v2.push_back(x); }  void println(const vector<int>& v) {     for (int x : v)         cout << x << ' ';     cout << endl; }  int main() {     vector <int> v1(3, 15);     vector <int> v2(3, 25);     append(v1, v2);     println(v1);     println(v2); }


Command that works fine typed into terminal does not work as a bash function

I have a function which is meant to keep a record of every program I've installed (really, I'm interested in keeping track of dependencies). I've tested out my command in a terminal and it works just fine:  dnf install sc | tee -a ~/Scripts/dnf_install.log  Note that sc is just the program I chose since I happened to want to test out a few spreadsheet programs (without bloating my computer with unremoved dependencies) and it's got a short name.  Anyway, so I want to make this a function so I put in my .bashrc the following:  # easier install with logging function install () {     dnf install $1 | tee -a ~/Scripts/dnf_install.log }   However, I always get this error:  ryan: ~ $ sudo install sc [sudo] password for ryan: install: missing destination file operand after ‘sc’ Try 'install --help' for more information.   After trying to narrow things down a bit, I'm pretty sure that the offending part of the code is dnf install $1 and not the part afterwards.  Can anyone explain to me what I'm screwing up and how/why the command is being treated differently inside a function than directly inputted?  Edit: issue solved. As don_crissti pointed out, "sudo forks/execs a new shell that doesn't know about your function." So I put sudo inside the function and also changed $1 to "$1" for good coding practice. I did not know this was a duplicate since I didn't know the issue had to do with sudo.