Question is to check if  $\prod \limits_{n=2}^{\infty}(1-\frac{1}{n^2})=1$  we have $\prod \limits_{n=2}^{\infty}(1-\frac{1}{n^2})=\prod \limits_{n=2}^{\infty}(\frac{n^2-1}{n^2})=\prod \limits_{n=2}^{\infty}\frac{n+1}{n}\frac{n-1}{n}=(\frac{3}{2}.\frac{1}{2})(\frac{4}{3}.\frac{2}{3})(\frac{5}{4}.\frac{3}{4})...$  In above product we have for each term $\frac{a}{b}$ a term $\frac{b}{a}$ except for $\frac{1}{2}$.. So, all  other terms gets cancelled and we left with $\frac{1}{2}$.  So, $\prod \limits_{n=2}^{\infty}(1-\frac{1}{n^2})=\frac{1}{2}$.  I would be thankful if some one can assure that this explanation is correct/wrong??   I am solving this kind of problems for the first time so, it would be helpful if some one can tell if there are any other ways to do this..  Thank you

While trying some problems along with my friends we had difficulty in this question.   True or False: The value of the infinite product $$\prod\limits_{n=2}^{\infty} \biggl(1-\frac{1}{n^{2}}\biggr)$$ is $1$.   I couldn't do it and my friend justified it by saying that since the terms in the product have values less than $1$, so the value of the product can never be $1$. I don't know whether this justification is correct or not. But i referred to Tom Apostol's Mathematical Analysis book and found a theorem which states, that    The infinite product $\prod(1-a_{n})$ converges if the series $\sum a_{n}$ converges.   This assures that the above product converges. Could anyone help me in finding out where it converges to? And,   Does there exist a function $f$ in $\mathbb{N}$ ( like $n^{2}$, $n^{3}$) such that $\displaystyle \prod\limits_{n=1}^{\infty} \Bigl(1-\frac{1}{f(n)}\Bigr)$ has the value $1$?


I have Debian 7 in console only mode; is there a way I can display different programs on 2 monitors?  example:  Screen one is the primary screen and this is to display my PoS application Screen two is the one that is facing the customer so I would like this one to display the "Customer graphical" program (basically it lists all items that have been brought so far plus a running total and item count)  Can this be done or have I managed to find something that is easier on Windows then Linux? (It is impossible on DOS as it only can handle one screen)

I would like to setup dual screens.  I've done multiple searches but there is nothing beginner-friendly for me to grasp exactly what I need to do to get the setup working.  I've picked up a few commands and here's what I have:  xrandr Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192 DVI-I-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 476mm x 268mm    1920x1080      60.0*+    1680x1050      60.0      1280x1024      60.0      1440x900       59.9      1280x960       60.0      1152x864       75.0      1024x768       75.1     70.1     60.0      832x624        74.6      800x600        72.2     75.0     60.3     56.2      640x480        72.8     75.0     66.7     60.0      720x400        70.1   DP-1 disconnected (normal left inverted right x axis y axis) DP-2 disconnected (normal left inverted right x axis y axis)   I suspect I should see either one of the following connected since I have the second monitor plugged in correct?    DP-1 disconnected (normal left inverted right x axis y axis)   DP-2 disconnected (normal left inverted right x axis y axis)   I seem to have an NVIDIA graphics card as per the following:  lspci -nn | grep VGA 02:00.0 VGA compatible controller [0300]: NVIDIA Corporation GK107 [Quadro K2000] [10de:0ffe] (rev a1)   Some system information:  No LSB modules are available. Distributor ID: Debian Description:    Debian GNU/Linux 7.4 (wheezy) Release:    7.4 Codename:   wheezy   How to set this up for what I need to do next?


This code scrapes website for a number and saves that number into JSON file - number.json: const axios = require("axios"); const cheerio = require("cheerio"); const fs = require("fs");  //performing a GET request axios   .get("https://ycharts.com/indicators/bitcoin_price")   .then((response) => {     //handling the success     const html = response.data;      //loading response data into a Cheerio instance     const $ = cheerio.load(html);      //selecting the elements with the data     const scrapedata = $(".key-stat-title").text();      //     let number = scrapedata.split('U')      //outputting the scraped data     console.log(parseInt(number[0]));      var express = require('express');     var app = express();      app.get('/', function(req, res){       res.send(number[0]); //replace with your data here     });      fs.writeFile("number.json", number[0],  err => {      // Checking for errors     if (err) throw err;      console.log("Done writing"); // Success });       app.listen(3000);   })   //handling error   .catch((error) => {     console.log(error);   });   When I look into 127.0.0.1:3000 when node is on - I see blank page only with that number. In the number.json is also that number. How can I use that number - save it - here in javascript file, in howMuchBtc variable, either get it straight from 127.0.0.1:3000 or get it from number.json??? function calculate(){   let input = document.getElementById('number').value   let howMuchBtc = input/0.05   let todayPrice = (howMuchBtc*31742).toLocaleString()   document.getElementById('newnumber').innerHTML = todayPrice }

I need to do an  request in JavaScript. What's the best way to do that?  I need to do this in a Mac OS X dashcode widget.


In the following example Python uses the same integer object in the memory for all three names x, y and z in the namespace  def main():     x = 0     y = 0     z = 0     print(x,y,z)     print(x is y is z)     y = 2     print(x,y,z)     print(x is y)     print(z is y)     print(x is z)  if __name__ == "__main__":main()   Output:  0 0 0 True 0 2 0 False False True   Why Python doesn't use the same tuple object here ( yes it is the choice of language designers but why) and a better questin to ask is when python creates new objects in memory  def main():     a = 1, 2, 3     b = (1, 2, 3)     c = 1, 2, 3      print(type(a) == type(b))     print(a == b)     print(a is b)     print(a == c)     print(a is c)  if __name__ == "__main__":main()   Output:  True True False True False

My  has failed me.  In Python, are the following two tests for equality equivalent?  n = 5 # Test one. if n == 5:     print 'Yay!'  # Test two. if n is 5:     print 'Yay!'   Does this hold true for objects where you would be comparing instances (a list say)?  Okay, so this kind of answers my question:  L = [] L.append(1) if L == [1]:     print 'Yay!' # Holds true, but...  if L is [1]:     print 'Yay!' # Doesn't.   So == tests value where is tests to see if they are the same object?


I'm trying to find all the javascript files in subdirectories of my project.  The working tree is as follows:  . ├── app ├── assets ├── components ├── email.txt ├── gulpfile.js ├── node_modules └── package.json   For that end I say:  find . -name *.js   or  find . -path *.js   Strangely, first command reports only gulpfile.js, while the second one reports nothing. But I have .js files in app, components and node_modules! Why wouldn't they show up?

Imagine a source tree. There are xml files everywhere.  But since there is a XYZ.xml at the root of this tree it won't find my xml files.  find -iname *.xml   returns  ./XYZ.xml   instead of  ./XYZ.xml ./a/b/c/bob.xml ./b/d/top.xml


I can not figure out what the correct usage of allow/allows is in this case.      Using plural allow(s) me to...   Would "allow(s)" refer back to the plural and thus be "allow"? or does it refer back to the action of using the plural and thus be "allows"?  An example could be something like: "Using old recordings allow(s) me to relive memories."

Making adult decisions are/is really not fun.     What is the proper answer and why? My gut says "is" but I can't explain why.


My PC has been infected with a malware that opens pop-up to some ads, mostly in my native language (Persian) but from (wonderlandads.com), when I click on a link or in an input box in StackExchange websites. Interestingly, it just occurs for these websites and no other website! It occurs in both Firefox and IE  I scanned my computer with NOD32 7.0.2 , and some freeware malware scanner (kaspersky tools,...), but they couldn't find it. I reinstalled the Firefox and disabled startups but couldn't fix it.  What is the cause? and what can I do?   How it can hide itself from powerful antiviruses and anti-malware?  ==============  Update It seems I could handle it by killing running processes and refreshing the firefox.

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


I am looking for the correct spelling of Polish surname Mihowski or   Mahowski? I hope to find cousins in Poland.

My Polish grandmothers last name was Dziubenofska, but I know that's not how it is spelt! I'm looking for the proper spelling.   Can you help find it for me?  She came over to Ellis Island and they changed it on her to dziuk. This is only a prefix to the full name.


I have a eclipse. I removed default eclipse from /usr/lib as,  sudo apt-get remove eclipse   Then I copied my eclipse folder to /usr/lib and tried to launch it as,  sudo eclipse   But I am getting the following error,  usr/bin/eclipse: 35: exec: /usr/lib/eclipse/eclipse: not found   My eclipse which I copied is present in /usr/lib. Why am I getting this error? My requirement is I have to remove the default eclipse and launch my own eclipse from /usr/lib.

I want to install the latest version of Eclipse but the Ubuntu Software Centre contains an older version.  Is there a PPA or some other way to install latest Eclipse? Please describe the steps for full installation.


The Dirac delta function sounds strange to me. How can you define such a function $\delta(x)$ such that $\int \delta(x) \,dx = 1$? I  mean $\delta(x)$ is $0$ almost everywhere and so by definition it's Lebesgue integral has to be $0$ as well.  Am I mistaken?

Is Dirac delta a function? What is its contribution to analysis?   What I know about it: It is infinite at 0 and 0 everywhere else. Its integration is 1 and I know how does it come.


Why do our limbs (legs, arms) get numb/feelingless when they are under prolonged pressure or when one has crossed his/her leg while sitting for a long period?  After we move it to a more relaxed or natural position numbness goes away and we get the really strange and hard to bear tickles. Why does the numbness go away by doing this and why do why get these odd tickles?

I have noticed that while sitting in the Sukhasan posture(picture below) for a long time, my feet suddenly become all stiff and i am unable to move it. What I deduce from the experience is that it is static, though I fail to understand how it accumulated at my feet.Does anyone have an explanation for this?


Suppose $A$ and $B$ are sets such that $\overline{A}\cap B = \emptyset = \overline{B}\cap A$. Furthermore, $A$ and $B$ can be written as a countable union of closed sets. I am trying to show that there exist disjoint open sets $U,V$ such that $A$ is in $U$ and $B$ is in $V$. I am not sure where to start.   Note this is all happening in a normal T1 space.

Let $X$ be a normal Hausdorff space and let $C,D$ be two $F_{\sigma}$ subsets of $X$ such that $\overline{C} \cap D = \emptyset$ and $C \cap \overline{D} = \emptyset$.  Prove there exists disjoint open subsets $U,V$ such that $C \subset U$ and $D \subset V$.  No idea how to show this. Can you please help?


I bought some "pineapple" post caps made of treated pine. When they arrived, I was taken aback to see, rather than an overall greenish tinge, splotches and patches of green. I tried to attach a photo but can't--something about needing "at least 10 reputation to post images"?!? I realize it'd be a lot easier if you could see a photo, but can anyone advise what went wrong? As my plan has been to leave these unstained, I will probably have to send them back-- unless someone knows how to "fix" this problem? Does anyone know of a company etc that sells a similar--hopefully better treated--product? I've had a hard time finding pineapple post caps like this, but I just don't think I can use these in their present condition.

I bought some "pineapple" post caps made of treated pine. When they arrived, I was taken aback to see, rather than an overall greenish tinge, splotches and patches of green. As my plan has been to leave these unstained, I will probably have to send them back-- unless someone knows how to "fix" this problem? Additionally, what caused these caps to look like they have green splotchy paint on them?


Here is a cartoon about password entropy.   I dont quite understand how the entropy is calculated in the cartoon assuming they are calculate correctly. But in general, I dont have much idea about how password entropy is calculated.

If part of the password is a whole regular English word, does the entropy of that part depend on the number of English words in existence, the number of English words known by the choosing algorithm, the number of English words assumed by the attacker?  Does the language matter, is the average entropy per word in German, French, Italian, or Spanish significantly different from the average entropy in English?  Does a numeric digit always have an entropy of $\log_2(10) = 3.321928$?


How can I evaluate the following improper integral:     $$ \int\limits_0^{\infty}\frac{\sin x}{x}\, dx$$    I have tried to evaluate this by integration by parts but failed. Please help

A famous exercise which one encounters while doing Complex Analysis (Residue theory) is to prove that the given integral: $$\int\limits_0^\infty \frac{\sin x} x \,\mathrm  dx = \frac \pi 2$$ Well, can anyone prove this without using Residue theory?  I actually thought of using the series representation of $\sin x$: $$\int\limits_0^\infty \frac{\sin x} x \, dx = \lim\limits_{n \to \infty} \int\limits_0^n \frac{1}{t} \left( t - \frac{t^3}{3!} + \frac{t^5}{5!} + \cdots \right) \,\mathrm  dt$$ but I don't see how $\pi$ comes here, since we need the answer to be equal to $\dfrac{\pi}{2}$.


I am looking for a command that I can use to locate a file by the date a file was created on my computer

What would be the best way to list 100 first files in a directory sorted by the created timestamp (oldest first). The directory is quite large (around 100000 files). ls piped to head takes an awful long time to complete.   Edit:  Filesystem is ext3. limiting the number of files in the folder is not worth the effort, since this is going to be a rare "clean-up" operation and files are generated by a 3rd party software.   Using file modified time, instead of the creation time provides and acceptable solution.


In all the action scenes I'm familiar with, the Force is used only on people or objects nearby within visual sight of the Force user.  However there are situations where force users can sense something outside their own physical perception limitations, such as when Vader knows that Luke is on a particular space craft, or when a million voices cried out and were silenced.  Given that Vader force chokes someone who failed him, is it possible for him to force choke someone who failed him, but isn't in the same room, or on the same planet?  Does Luke's ability to sense when his friends are in danger also suggest that he is able to help them at a distance, or communicate with leia at a distance?

In the Star Wars universe, could a Jedi Mind Trick be performed over the telephone?   For instance, could Yoda have called up the Imperial embassy on Dagobah and mind tricked whoever answered into getting him in touch with Palpatine? (I know there's no embassy or telephones on Dagobah, but serious question nonetheless.)   To clarify, are long distance mind tricks not only possible but would being in communication with another person, through telecommunication, allow a force user to better perform the action?


I have no problems finding JREs, JDKs and documentation for core Java SE packages, but I'm not sure where to get the source (.java) files.  I'm looking for the latest stable release, not bleeding-edge development code.  Where are those available?

I want to have a look at how Java implements LinkedList. Where should I go to look at the source code?


Suppose, there is a Limit sell order with Limit Price : 21, Qty   : 21000  then another new Limit sell order placed as below Limit Price : 20, Qty   : 200  Now if a new limit buy order placed as below, Limit price : 21, Qty : 400  I agree, buy Limit order should match with Lowest sell order available. But If buy limit order has exact match available with Limit sell order, then with whom buy order should match? i.e Which order should get high profit buy order or sell order in case there is a exact match order?

Say a security has been trading at under $20.10, and there are limit orders selling at $20.10 and $20.21. Then Simon issues a limit order to buy at $20.21. According to , Simon would end up buying shares at $20.10.  Why does the exchange favor the buyer here?  I.e., why does the transaction execute at the seller's limit of $20.10 instead of the buyer's limit of $20.21?  (I.e., why don't Inara/River get to sell at $20.21 / above their limit, but Simon gets to buy at $20.10 / below his limit?)  Is the example flawed?  If it makes a difference, I'm mainly curious about NASDAQ and NYSE.  I tried Googling for specs (e.g. ), but couldn't find anything.  Only found that some  implementation executes the average of the buy/ask.  Just curious how the system works.


Articles confuse me very much. Please, can anyone tell me which articles should I put in these sentences and why:     __ horse in this photo is beautiful. Is that __ girl or __ boy on its back?        __ castle on that hill is very old. Is that __ bird or __ plane up there (above the castle in the sky)?    In these sentences, I think, "The" article should be in front of 'horse' and 'castle' but which articles should I put in front of the other two words in each sentence?

How do I know whether to use the definite (the) or indefinite (a, an) article, and when to omit it altogether?


Since I got into League of Legends in Season 2, I'm wondering what was the most important tournament in season 1, and who won it?

Is there a tournament that is comparable to the Super Bowl, World Series, Stanley Cup Playoffs, FIFA World Cup, Daytona 500, etc.? Or does LoL not have seasons in the traditional sense of other sports. I ask this because it says that the game is in Season 2 so I'm curious.  Is there an all-defining championship for LoL?


Could someone please explain the grammar used in the text below?     Officers are convinced the bloodshed at the Christian school would   have been worse had Meis and the others not intervened.      Source:    According to what I have learned so far it should be :     Officers are convinced the bloodshed at the Christian school would   have been worse if Meis and the others had not intervened.

Can this:     These same officials, however, would have been appalled had they known what was going on behind this façade of self-help.   be rephrased as     These same officials, however, would have been appalled if they had known what was going on behind this façade of self-help.   ?


I tried to do this myself, but I am a newbie with regex.  I have this URL:  http://[DOMAIN]/[category]/27466-some-article-is-here   Which should redirect to this URL:   http://[DOMAIN]/[category]/some-article-is-here   I simply want to remove the ID from the URL. The category could be anything, which I want to keep.  How do I achieve this?  UPDATE: I adjusted the Redirect from @taduuda to this:  RewriteRule ^(.*)\/[\d]*\-(.*)$ $1/$   This looks good with a testing tool, but this still doesn't work on my wordpress site.  My htaccess:  # BEGIN WordPress <IfModule mod_rewrite.c> RewriteEngine On RewriteBase /  # BEGIN - Custom Redirects RedirectMatch 301 /heute(.*) /$1 RewriteRule ^(.*)\/[\d]*\-(.*)$ $1/$2 # END - Custom Redirects  RewriteRule ^index\.php$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L]  </IfModule> # END WordPress

This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not.


It looks all messed up. I can see the preview of the photo but when I open it, it is just bars of colors. When I tried to upload it here to show you guys, it said framing is not allowed and wouldn't let me upload it. Anyone how to fix it? I will appreciate it very much as they are all wedding photos.  Well, the duplicate question does not answer my question nor does it give me a solution. If you open your eyes and look, the images are totally different. Mine is completely messed up and that other photo isn't that bad. So, if you want to mark it as duplicate, at least make it so the other question has a SOLUTION TO MY PROBLEM.  On another note, I am able to preview the images fine with a medium thumbnail setting. When I change it to large, I see the messed up image. By preview, I mean see the thumbnails in the folder.

I have had my Nikon D40 for a while, and some of the pictures are coming out distorted. Two examples are below:   So my questions are:    How do I fix them after the fact? - i.e. after they have been imported from the camera - if possible How do I prevent future pictures from being distorted like this?   Thanks   and


Below is my html and javascript. The Js is located in a app.js file and the html is a yes or no question. At the bottom of the javascript I have code that should fire on click events. Right now it is just to see if it detects a click on the p elements in the html but hasn't worked so far.  Can anyone detect why this event isnt taking place?  The other jQuery int he code does work but this jQuery isnt invoked by a function and is invoked based of strictly using a selector which leads me to believe there is something wrong with how I used document.ready in my project.  Html:

Do you know your individual monthly rent cost?

Yes

No

   Javascript:   var quest = ['../partials/income.hbs', '../partials/state.hbs', '../partials/rent.hbs', '../partials/zip.hbs', '../partials/roomate.hbs', "../partials/summary.hbs"];     var iterator = 0;     //creates object that gets sent to api     function Obj(name, vale){          event.preventDefault(); //prevents pg refresh          $('.form').load(quest[iterator], function () {             $('.bar p#' + name).css("border","2px solid black").addClass('enter').next().css({"border":"2px solid black","pointer-events":"auto","cursor":"pointer"});         });         //loads next html question to page        if(name){              data[name] = vale;         }         //move array accessor up to next question         iterator++;          console.log(data);     }     var data = {};       //user can click already submitted values to load that orignal question and change it/     function redo(q, id) {         q = Number(q);         //if the current queston on the page is not the one being clicked we then change it to the one being clicked         if (q + 1 != iterator) {             $('.form').load(quest[q], function () {                   $('#p').val(data[id]);             });             iterator = q + 1;         };     };      $(document).ready(function(){     $('.rentanswer p').on('click',function(){        console.log('hey');      });     });

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


I'm having different classes. Now in one class, I'm having the following method/function.  class Currency extends CurrencyClassAbstract {      public function __construct(      }        public function convertMethod($price) {          //need to know here which class is calling this method/function      }  }   Now, there are different classes like product, tax, cartclass, orderclass all these classes are calling convertMethod function of Currency class.  I need to write code in convertMethod of Currency from where (which class) it is calling?  Is there any possible way to do this?

Is there a PHP function to find out the name of the caller function in a given function?


I'm having some difficulty aligning two divs in the center of a page. Instead, it remains left. I've combed through this site, and others, and have tried several of the suggestions. I am thinking maybe I've bungled it by taking from several different examples and putting it to one, and something is negating the other? The divs just aren't aligning center on the page. I have the masking gif in one div, and the writing in another div, and placed those two divs within a container.    body {   background-color: #000;   color: white;   font-family: "Cutive One", monospace;   font-size: 13px;   text-align: justify;   line-height: 1.5; }  .container {   margin: 70px;   width: auto; }  .one {   width: 35%;   max-width: 300px;   min-width: 300px;   padding: 5px;   text-align: center;   float: left; }  .two {   width: 35%;   padding: 5%;   max-width: 300px;   min-width: 300px;   float: left;   background: black;   font-family: "Cutive One", monospace;   font-size: 13px;   text-align: justify;   line-height: 1.5; }  .gif {   background: url("http://78.media.tumblr.com/072a9aee9e56415e20ffd06c3260c49d/tumblr_n85ga7OASY1qmxnvuo2_500.gif") repeat;   background-position: 10px;   -webkit-background-clip: text;   color: transparent;   font-size: 200px;   font-family: Fjalla One;   font-weight: bold;   text-align: center;   letter-spacing: 3;   background-position-x: 50%;   background-position-y: 50%; }

TXT

Test //

Test

Test

Test

How can I horizontally center a
 within another
 using CSS?

Foo foo


Let's say I have a shop where the shopper have to login first, for the sake of example. There is a page called /cart where users can see all of the products they added to the cart from previous pages and proceed with the checkout. If the user is not logged in yet the /cart will go to /login and then will go to /success. Otherwise it will go to /success directly.  Using Google Analytics, how do I know   How many users want go to through the trouble of putting their credentials to process the cart? How many users don't want to do it? How many users that are already logged in, i.e. don't go through the /login? (assuming I don't track the user type using Custom Variables).

I have an online shop with a blog structured this way:   Shop: example.com Blog: example.com/blog   Both index have the same Google Analytic Code (UA). In the blog I write articles about some products with a link to the product page.  Now the problem is, I want to see stat on visits whose referral links have this pattern example.com/blog/*.


The problem states: If roots of $x^4 + ax^3 + bx^2 + ax + 1 = 0$ are real, find the minimum value of   $$a^2 + b^2$$  Im really not very good at these types of questions as they seemingly provide very little information.  So, I am basically stumped by this. I first thought that, since the roots are real, $x^4$ and $x^2$ should be positive, which would imply the others are negative. But wont know anything about $a$ or $b$, so really Ive no idea. Id like a hint and not the full solution, so that I can get better at solving such problems. Thanks.

I just wanted the solution, a hint or a start to the following question.  Determine the minimum of $a^2 + b^2$ if $a$ and $b$ are real numbers for which the equation $$x^4 + ax^3 + bx^2 + ax + 1 = 0$$ has at least one real solution.  Thanks in advance.


In this question, we consider strings consisting of 26 characters, with each character being a uppercase letter. Determine the number of such strings that    (a) start and end with the same letter, or    (b) are palindromes, or    (c) contain vowels only   For this problem, I approached each scenario a, b, c separately. I then joined the 3 with an OR to satisfy the question in the final answer.  a. $26$ characters, if the last letter must be the same as the first, we really only have $25$ characters to choose from, so part a = $26^ {25}$  b. $26$ characters, but if it is a palindrome, the length is cut in half, giving us $26^{13}$.   c. If the characters are vowels only, there are only A E I O U, $5$ characters to choose from. And we have a full 26 characters to pick. $26^{5}$  The three value then gets OR'd together  $26^ {25}$ OR $26^{13}$ OR $26^{5}$    Is what I did correct? I'm working from practice problems and am not given an answer key so it's hard to really practice when I don't know if I'm doing it right or wrong. Thank you!

I have a question about this problem that I am trying to figure out:  A string of letters is called a palindrome, if reading the string from left to right gives the same result as reading the string from right to left. For example, madam and racecar are palindromes. Recall that there are five vowels in the English alphabet: a, e, i, o, and u.     In this question, we consider strings consisting of 28 characters, with each character being a lowercase letter. Determine the number of such strings that    (i) start and end with the same letter, or    (ii) are palindromes, or    (iii) contain vowels only.   My answer so far:  $A = 26^{27}$,  $B = 26^{14}$,  $C = 5^{28}$  My question is, would I have to use a sum rule here or inclusion-exclusion rule? I am not sure about which method to use here. Any help would be appreciated.


When TeX4ht compiles my latex code it generates a png of my equation and includes this in the html file.  Until a better alternative for this comes along I am quite happy with this way of managing/presenting my equations.    This is a collaborative project and I am working with some very anti-latex and anti software people, so I generate html files that they can edit.  By ensuring complete compatibility between the html file and pdf generation everyone remains happy.  I would however prefer to have a higher resolution image that my collaborators can read without getting frustrated with the document quality.    Approaches I have investigated and been unsuccessful with:     An excellent explanation that I apologize for missing during my initial week spent trying to solve this issue here  uses a conversion of eps to svg.     Unfortunately eps are not file extensions that my collaborators can open, nor is it something they are willing or even capable to upgrade software to work with.  So This solution is not my preferred approach unless the final image type is not an eps.    I am sure I am not doing something quite right with the implementation of this as on our work computers I am left only with the eps file, no png or svg are created, and browser/editable integration of the eps is hit or miss.  If memory serves, the mentioned convert program is part of imagemagick which we do have installed, so I am at a loss why the svg or png creation is absent using the custom cfg file mentioned in the solution.  Maybe this should be the question itself which I believe is completely distinct albeit related to the question that this is currently marked as a duplicate for.   It might be neat to use a completely different approach maybe using  which honestly I haven't even been able to figure out how to compile their examples - but I feel it holds promise for the issue I described above if I can figure out what it is supposed to do and how to do it (unless this tool is the best option to solve my problem, this is a question for another day which I will post and edit this question to remove this aspect to prevent duplication).  One aspect of this approach that would interest me, is the appearance that this is not a picture, but formatted text...   Here is my MWE.  \documentclass{report}   \usepackage{amsmath} \begin{document}         \begin{equation}             \text{C~=~}{\frac{a}{b}}         \end{equation} \end{document}

I'm using tex4ht to produce XHTML files from a LaTeX file. The XHTML file I obtain uses images for some equations which tex4ht could not convert directly to XHTML.   Problem: images of equations have very bad quality.   What I want: Better quality images.  More info on attempts & system:  I'm using MikTeX 2.9 under Windows Vista. I go to the command line and type htlatex document.tex "xhtml" to get the resulting XHMTL file.   After doing some search on the web, I tried to change the file tex4ht.env as mentioned in  (changing -density 110x100 to -density 220x220 -geometry 50%) in all locations I could find in my system (within the MikTeX path and also in the AppData windows directory) but the results are the same. I obtain during the compilation of hlatex the following line (among others):     System call: mgs -sDEVICE=pngalpha -sOutputFile=Untitled11x.png   -r110x110 -dEPSC rop -dBackgroundColor=16#ffffff -dTextAlphaBits=2 -dGraphicsAlphaBits=2 -q -dbat ch -dNOPAUSE zzUntitled1.ps -c quit   In particular, I would guess that the -r110x110 means resolution was still set to 110x110, despite my changes to the file tex4ht.env.  Any suggestions on how to improve the quality of equations images?


How to use or operate an ini file using C#. Like reading, writing section, keys, values. I heard about nin.dll(or something like that) but I unable to use it. Also i am using sharpdevelop and dot net version 4.0 Thanks in advance.

Is there any class in the .NET framework that can read/write standard .ini files:  [Section] <keyname>=<value> ...   Delphi has the TIniFile component and I want to know if there is anything similar for C#?


I want to show that the Cardinalities of $\mathbb{R}[X]$ and $\mathbb{R}$ are equal.  For starters, I tried mapping each polynomial to $\mathbb{R}^n$ by mapping it to its coordinates vector, but its not correct (I am limiting my polynomials here)  I can use cardinalities arithmetic and Cantor - Bernstein theorem.  Would love to get some insight.

What is the cardinality of the set of all polynomials with real coefficients? I know the power set of $\mathbb{R}$ is "more infinite" than $\mathbb{R}$, so to speak, but I'm unsure of how to prove that there does or does not exist a surjection onto $\mathbb{R}[X]$ from $\mathbb{R}$. Is it equinumerous with the power set of $\mathbb{R}$, or something else more exotic?


//The Prompt is: Write a program that asks the user to enter a string, and //then ask the user to enter a character. The program should count and display //the number of times that the specified character appears  in the string.  import java.util.Scanner; public class LetterCounter{ Scanner keyboard = new Scanner (System.in);     //Scanner // Declare Variables     String userString;      // String user entered     String userCharacter;   // Character user entered     int StringSize;       // Ask the user to enter a string     System.out.println("Please Enter a String.");     userString = keyboard.nextLine();  // Ask the user to enter a charcter     System.out.println("Please Enter a Character.");     userCharacter = keyboard.nextLine();  // Count and display the number of times that character appears in the // string chosen by the user.     int character;      character = Integer.parseInt(userCharacter);     StringSize = userString.charAt(character); } }   For some reason I can't get it to work, I just don't know where to go from here. Do I possibly need a FOR-LOOP?  Thanks for your help

I have the string   a.b.c.d   I want to count the occurrences of '.' in an idiomatic way, preferably a one-liner.  (Previously I had expressed this constraint as "without a loop", in case you're wondering why everyone's trying to answer without using a loop).


Every time I watch this TV program that discusses about all the facts about the universe , and it came to a point where they said that as an object approaches the speed of light the mass of the object increases and space decreases , my question is that if an object has very energetic particles in it like that of the sun then wouldn't its mass be higher hence making its gravity greater than that of the still state ones ?

If an object was sliding on an infinitely long friction-less floor on Earth with relativistic speeds (ignoring air resistance), would it exert more vertical weight force on the floor than when it's at rest?


I am using different regression models that can predict an ordered categorical variable from a metric variable. For example, I want to regress Happiness (in 1-5 ratings) on Money (a metric variable) using  regression:  $Happiness \sim log(Dollars)$  But I came across a fundamental question: How can I compare the accuracy of different models in predicting ordered categorical data?  If I do an ordered probit regression, cross-validating model prediction accuracy with 80% data for training and 20% for validation, I can compare the probability distribution of real data with what probit provided, but in this way, the order is ignored, and for example if it predicts every rating $Y$ with the opposite rating $(Y+4)\%5+1$ (exactly opposite), the result doesn't change!  So, what should I do? I found , but nothing quantitative.    Figure 1. Fictitious report for a probit regression, based on

I want to do an , then cross-validate model prediction accuracy with 80% data for training and 20% for validation, and calculate  for predictions.  Consider this dataset:    X     Y ----------  2.3    1  3.1    2  3.5    2  10.0   5  6.8    4  5.0    3  5.4    2  3.2    1   I did this:  x=c(2.3,3.1,3.5,10.0,6.8,5.0,5.4,3.2) y=c(1,2,2,5,4,3,2,1) myData=data.frame(cbind(x,y))  library("MASS") reg=polr(as.factor(myData$y)~myData$x,data=myData,method="probit")   I saw , but I couldn't fully understand. Suppose myValidationData contains 20% of data which I want to use for validation. So, I would do:  fit=predict(reg,type="probs") x=c(5.6, 5.1) y=c(3,3) myValidationData=data.frame(cbind(x,y))   This is how I tried to predict, but is it correct, when I want to cross-validate?  fit=predict(reg,data=myValidationData,type="probs")   How should I measure RMSE? And, how can I plot the prediction?


Given $d = gcd(c,n)$, why there exist relatively prime integers r and s, such that $c = rd$ and $n = sd$?

Prove that if $d$ is a common divisor of two integers $a$ and $b$, then $d=\gcd(a,b)$ if and only if $\gcd(a/d,b/d)=1$.   So far I used what was given so I have $a=dk$, $b=ld$ and $\gcd(a,b)=d$ can be written as a linear combination of $ax+by=d$ but I am unsure how to use the information.   Where do I go from here? Can someone show me how to solve this using Bezout's Identity if possible?


I know, it's not a macro (or, in Nikon terms, Micro) lens. But, want to use it that way sometimes.  Though, for budget's sake, i was considering a Tamron AF 70-300mm(F/4-5.6 Di LD Macro), but, ended up buying Nikon 55-300mm for overall value. I tried to utilize a closeup filter, but it was a frustrating experience.  Is there any to utilize for macro shot by using any technique, or any close-up filter, or any other way ?  Do you have any experience to share?  p.s. My camera is a D5100

I am a photography newbie and have only a 18 - 135mm canon kit lens at my disposal. I wanted to take macro shots but can't really afford a macro lens right now. One very optimistic goal of mine is to capture a single snow flake this winter.   Is there any cheap(er) way to take macro shots? Also, any specific advice from anyone one how to go about photographing a single snow flake.


I had seen this proof at many places, but  everywhere sylows theorem is used.   So is their any way to solve it without using sylows theorem?

Prove that, any group of order $15$ is abelian (without help of Sylow's theorem or its application).  What I have done so far is,   by class equation we know that $|G|=|Z|+\sum\frac{|G|}{C(a_i)}$. Now if I can show that $|G|=|Z|$ then the theorem is proved. Now order of $|Z|$ can not be $3$ or $5$, because if it is then $(G/Z)$ will be cyclic,which can not be since $G$ non-abelian.So, only possibilities are $|Z|=1$ or $15$. Now haw can I conclude that $|Z|\not=1$?


I'm running Windows 7 x64, and since yesterday, it's been constantly writing to the hard disk from PID 4, to no purpose. I've tried disabling updates and antivirus, but this makes no difference. Apparently cache prefetching can generate spurious disk traffic, but presumably that would be just reads, and this is specifically and almost entirely writes.  What else could be causing it? Is there a way to find out what's generating the write traffic?  Edit: not a duplicate because:   This is specifically and only writing, not reading. The answers to the other question discuss Windows updating (which I have already tried disabling), sharing the C drive (which I'm not doing) and Autodesk software (which is not installed on this machine).

I have a problem that my windows 7 computer sometimes starts accessing the disk like crazy for maybe 10 minutes at a time. The process in question is the "system" process. I have disabled superfetch and hibernation on my computer, if that makes any difference. I disabled those to see if they were the cause of the problems, but no change. I have 6 GB of RAM and only the web browser was started when I took the screenshot, so I don't think it was thrashing due to page faults.  Any ideas on how to find the cause of this?


What is the best version/distro of Ubuntu for an aging IBM Thinkpad T60 laptop?

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


I want to prove the statement that completion of a ring w.r.t. maximal ideal is local. Let $\mathfrak{m}$ be a maximal ideal of a ring $A$, and $\hat{A}$ be an $\mathfrak{m}$-adic completion of $A$. I know that my statement can be verified if an element $$X:=1+\Sigma_{i\geq1} x_i $$in $\hat{A}$is unit in $\hat{A}$ ($x_i \in \mathfrak{m}^i$). Using the geometric series, we should verify that $$1/X = 1/\{{1-(1-X)}\} = \Sigma(1-X)^i$$ is an element in $\hat{A}$. But I don't know why this element is in $\hat{A}$, because even though a general element in $\hat{A}$ can be represented by infinite series with each term lies in $\mathfrak{m}^i$, but $$1/X = \Sigma(1-X)^i = 1-(x_1+x_2+\cdots)+(x_1+x_2+\cdots)^2-\cdots $$ contains infinite operation "in $\mathfrak{m}^i$", which is absurd. Can anyone tell me why we can say that $1/X$ is in $\hat{A}$?

Let $R$ be a commutative ring with unit and let $m$ be a maximal ideal of $R$. Are there known conditions on $R$ or $m$ such that the $m$-adic completion $\hat{R}$ of $R$ is a local ring.   Since the completion of a Noetherian local ring is again local, I'm primarily interested in cases where $R$ itself is not local.   An example is the polynomial ring $R=k[X_1,...,X_n]$ ($k$ a field) with $m=(X_1,...,X_n)$ where the power series ring $\hat{R}=k[[X_1,...,X_n]]$ is local with maximal ideal $(X_1,...,X_n)$.


I have a Sandisk UltraPlus 16GB card—used in a Canon Powershot SX30IS—on which nearly every frame has been erased…I don't know how.  I do not format.  I use the card as storage.  I use a card till it's full, then insert a new card.  I do not erase images either.  This just leaves a messy black blank amidst filled frames.  I do not use a computer to view images. My Asus erases a frame if I click reverse.  I view images through the screen on the camera.  I print paper pictures at Walgreen's on their digital-to-print machines.  I know what used to be on the subject card.  I reviewed and made notes. I have printed some of the images.  But when I wanted to print the remaining frames, nearly everything had been erased. The frames remaining are interrupted by erased frames, though they were made on the same two consecutive days.  I can't figure out how they were erased. I seldom go to menu except to correct the date when I change time zones.  My thick fingers often mis-hit buttons on the camera, but none of them should cause erasing.  I've tried to recover with the camera club's WIN Recovery software, with no luck.  What happened and what do I do to retrieve the erased frames?   (I'm emailing SanDisk, but their tech either knows nothing or is hiding something.)

My technophobe mother returned from a European trip to discover she'd erased all but 15 images from a nearly full 2GB card. As I am the computer guy in the family, she posted the card to me and asked that I make something magical happen.  The photos were taken with and deleted by a Nikon Coolpix. (I don't know the model.)  I am a Linux guy, but there is a Windows Vista box at my disposal.  What is my best strategy to try to recover something?


Is the tipping culture prevalent in Australia ? Especially at restaurants ?  How much should I tip after a meal costing $50 (incl taxes) at a restaurant ? (The food is horribly expensive and the portions are small compared to the US) Also, do I have to tip at barber shop ?

I will be travelling to Sydney and just wanted to know about the tipping etiquette in Sydney.   I have read somewhere that the Service tax is already included in the price and there is no need to tip. Also, in countries like US (NYC specifically), bartenders/waiters are paid minimum wage and therefore there is a culture of paying tips. Is it similar in Sydney?  Is it required to tip the taxi drivers?


Can we have a map $f$, holomorphic on the open unit disk, such that $|f(z)|\rightarrow \infty$ as $|z|\rightarrow 1$? I think not, (at least I can't think of any such map), but I'd like to be able to prove this.

I had to solve the following question in an exam:     Prove that there is not a holomorphic function on a bounded domain   $\Omega$, $f:\Omega \to \mathbb{C}$ such that $\lim_{z \to w} f(z)= \infty$ for every $w \in Fr(\Omega)$ where Fr denotes the boundary of   $\Omega$.   The exam suggested that one should proof that in this situation $f$ could not have zeros in the domain. I did the exercise in this case, but how can I proof that $f$ has no zeros in $\Omega$?


I was trying to upgrade the system but every time its get failed on the Firefox. Even after the error i have tried Sudo Apt-get update then Sudo Apt-get upgrade but same error. Please kindly help me to fix it. Thanks in advance.

When I check for updates, I get a "Failed To Download Repository Information" error.   This is what comes up under details:   W: Failed to fetch gzip:/var/lib/apt/lists/partial/us.archive.ubuntu.com_ubuntu_dists_natty_main_source_Sources  Hash Sum mismatch,  E: Some index files failed to download. They have been ignored, or old ones used instead.


The question is to find $\lim\limits_{n\to\infty}{n\left(\left(1+\frac{1}{n}\right)^n-e\right)}$.  I am trying to use L'Hospital Rule, then I have $$\lim_{n\to\infty}{\frac{(1+\frac{1}{n})^n-e}{\frac{1}{n}}}=\lim_{n\to\infty}\frac{{n(1+\frac{1}{n})^{n-1}*(-\frac{1}{n^2})}}{{-\frac{1}{n^2}}}=\lim_{n\to\infty}{n\left(1+\frac{1}{n}\right)^{n-1}}=\infty.$$  I feel I made some mistakes somewhere, and I appreciate anyone can point out for me. Or if my method is wrong, I hope to get some hint on how to solve this one.

I am stuck on how to calculate the following limit: $$\lim_{x\to\infty}x\left(\left(1 + \frac{1}{x}\right)^x - e\right).$$  Definitely, it has to be through l'Hôpital's rule. We know that $\lim_{x\to\infty} (1+(1/x))^x = e$. So, I wrote the above expression as $$\lim_{x\to\infty}\frac{\left(1 + \frac{1}{x}\right)^x - e}{1/x}.$$Both numerator and denominator tend to zero as x tends to infinity. I applied l'Hôpital's rule twice, but I got the limit equal to infinity which is clearly wrong. In the book, it says that the limit should be $-e/2$.  Any help please? Also, in case someone managed to solve it, please tell me which numerator and denominator did you apply your l'Hôpital's rule to in both cases? Thanks a lot  Also, guys can you tell me how to write equations in this forum? Thanks.


how to get superuser mode to normal mode. When i install my system with ubuntu 16.04.3 it is in superuser mode ican't install new softwares how it overcome i try to install from software center and terminal when i open my software center like this,    i try to install from terminal   sudo apt-get install synaptic  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


I will post my own answer below. That should not deter others from answering.  There are many ways to prove this.

This is just a curiosity. I have come across multiple proofs of the fact that there are infinitely many primes, some of them were quite trivial, but some others were really, really fancy. I'll show you what proofs I have and I'd like to know more because I think it's cool to see that something can be proved in so many different ways.  Proof 1 : Euclid's. If there are finitely many primes then $p_1 p_2 ... p_n + 1$ is coprime to all of these guys. This is the basic idea in most proofs : generate a number coprime to all previous primes.  Proof 2 : Consider the sequence $a_n = 2^{2^n} + 1$. We have that  $$ 2^{2^n}-1 = (2^{2^1} - 1) \prod_{m=1}^{n-1} (2^{2^m}+1), $$  so that for $m < n$, $(2^{2^m} + 1, 2^{2^n} + 1) \, | \, (2^{2^n}-1, 2^{2^n} +1) = 1$. Since we have an infinite sequence of numbers coprime in pairs, at least one prime number must divide each one of them and they are all distinct primes, thus giving an infinity of them.  Proof 3 : (Note : I particularly like this one.) Define a topology on $\mathbb Z$ in the following way : a set $\mathscr N$ of integers is said to be open if for every $n \in \mathscr N$ there is an arithmetic progression $\mathscr A$ such that $n \in \mathscr A \subseteq \mathscr N$. This can easily be proven to define a topology on $\mathbb Z$. Note that under this topology arithmetic progressions are open and closed. Supposing there are finitely many primes, notice that this means that the set $$ \mathscr U \,\,\,\, \overset{def}{=} \,\,\, \bigcup_{p} \,\, p \mathbb Z $$ should be open and closed, but by the fundamental theorem of arithmetic, its complement in $\mathbb Z$ is the set $\{ -1, 1 \}$, which is not open, thus giving a contradiction.   Proof 4 : Let $a,b$ be coprime integers and $c > 0$. There exists $x$ such that $(a+bx, c) = 1$. To see this, choose $x$ such that $a+bx \not\equiv 0 \, \mathrm{mod}$ $p_i$ for all primes $p_i$ dividing $c$. If $a \equiv 0 \, \mathrm{mod}$ $p_i$, since $a$ and $b$ are coprime, $b$ has an inverse mod $p_i$, call it $\overline{b}$. Choosing $x \equiv \overline{b} \, \mathrm{mod}$ $p_i$, you are done. If $a \not\equiv 0 \, \mathrm{mod}$ $p_i$, then choosing $x \equiv 0 \, \mathrm{mod}$ $p_i$ works fine. Find $x$ using the Chinese Remainder Theorem.   Now assuming there are finitely many primes, let $c$ be the product of all of them. Our construction generates an integer coprime to $c$, giving a contradiction to the fundamental theorem of arithmetic.  Proof 5 : Dirichlet's theorem on arithmetic progressions (just so that you not bring it up as an example...)  Do you have any other nice proofs?


I have asp mvc site www.mysite.com. I want to create controller with method, that returns view on specific url - register.mysite.com. I want to create hidden section of mysite for admins to add new data into site DB. How i can do id?

Is it possible to have an ASP.NET MVC route that uses subdomain information to determine its route?  For example:   user1.domain.com goes to one place user2.domain.com goes to another?   Or, can I make it so both of these go to the same controller/action with a username parameter?


I just received my Schengen visa to visit France with multiple entries. I want to travel to Czech Republic after visiting France and I was wondering if I have to produce hotel reservations and return plane tickets at the Czech border control? As I have never been to Europe before I don't know how Schengen visa works.

My wife was just issued a multiple entry visa by France, which is good for one year.  Our first trip will be to France, the issuing country.  My question is: after we leave the EU and return, must future trips also start in France? Or may we go directly to (say) Greece from the US on a later visit?


I have a dataset, say 9000 rows, with some features. Around 8000 belong to class 1 and 1000 to class 0. So, if I am creating a model with any method say SVM, LR, Random forest the model has a tendency to give more prediction to class 1. So I have two things in mind:  a) I want to separate 8000 rows belonging to class 1 into 4 groups and use each group with those 1000 rows belonging to class 0 and create a model. After that I thought of averaging over the models. My first question is, averaging over the models as in theory means really what. Does it mean that we have to sum over the coefficients of each model and take the average? I am stuck with that part of averaging. And is my approach a good one?  b) Another approach I am thinking of is to replicate the 1000 rows belongs to class 0 8 times to get 8000 rows of 0. So, total data will be 16000. Will the duplication result in new information? Will it tend to overfit?  Is there any approach to deal with these unbalanced data?

We already had multiple questions about unbalanced data when using , , ,  and a number of other similar questions, what makes it a very popular topic! Unfortunately, each of the questions seems to be algorithm-specific and I didn't find any general guidelines for dealing with unbalanced data.  Quoting , dealing with unbalanced data     (...) heavily depends on the learning method. Most general purpose   approaches have one (or several) ways to deal with this.   But when exactly should we worry about unbalanced data? Which algorithms are mostly affected by it and which are able to deal with it? Which algorithms would need us to balance the data? I am aware that discussing each of the algorithms would be impossible on Q&A site like this, I am rather looking for a general guidelines on when it could be a problem.


Someone knows how can I use android apps in my pc using software from the Ubuntu archive ?

Is it possible to run Android apps on Ubuntu? And I don't mean inside an emulator, but natively, as you would with any other application installed using the Ubuntu Software Center.


I’m currently working on a Magic Missile-centered build and want to make sure I’m not missing anything.  As far as I can tell, using Hexblade’s Curse (XGtE 53) and Empower Evocation (PHB 117) are the only ways to increase my Magic Missile damage outside of upcasting.  So assuming I have 20 Int and a proficiency bonus of +6, is 1d4+12 the maximum damage I can do per missile by RAW?

So one of this question's  answers got me curious. What is the maximum damage a 20th level character can do with a 9th level Magic Missile by the rules to a single target.  So my best I've been able to find is Aasimar or Goblin WLK 1/WIZ 19   9th Level slot (1D4+1)(11) [keep in mind you only roll once for damage not 11 times]  per  Empowered Evocation (+5)(11) (assuming 20 INT) Hexblade Curse (+6)(11) (Proficiency Bonus +6)    Radiant Soul/Fury of the Small +20 (Level 20 Aasimar/Goblin)   For a total of (D4+12)(11)+20 for (min-max)avg (163-196)179.5  Am I looking at this correctly? Are there other abilities out there that can increase this?  Feel free to include non legendary magic items. NO TOMES PLEASE  Only use things available on D&D Beyond please.  Acceptable books are :   Basic Rules DMG, MM, PHB Sword Coast Adventure's Guide The Tortle Package Volo's Guide to Monsters Xanathar's Guide to Everything and any officially released Adventure Book


Travelling to London, UK for a 3 day competition from India. I am staying in UK for 5 days. I Want to apply for a general visa of less than 6 months. How much money should be in my bank account or in my parent's account? and what documents are required?

I am an Indian citizen studying in Italy on an Italian visa that expires 19 November, 2015. I have permesso di soggiorno. I want to visit the United Kingdom for my vacations for a week during March. I know the procedures already, however I am a little bit confused about the amount that I must show as a proof of support with my bank statements. I will stay for a week with my friends who are also students in Italy and will be in London for 5 days. What would be the amount in Euros that I need to show for my visit to UK?


What are the bounded lattices $\mathcal{L}=(Q,\lor,\land,\bot,\top)$ called that are isomorphic to topological spaces? I.e. those such that there exists a topological space $(X,\tau)$ and a bijection $f:Q\to\tau$ such that $f(\top)=X$ and $f(\bot)=\emptyset$ with $f(\bigvee_{i\in I}x_i)=\bigcup_{i\in I}f(x_i)$ and  $f(a\land b)=f(a)\cap f(b)$? It would seem the study of these lattices is essentially just the study of point-set topology, thus I imagine they must have a name? What are they called?

When a lattice $(L,\leqslant)$ is a lattice of open (or closed) sets of some topological space $(X,\tau)$? Which conditions have to be satisfied? We may assume that $X$ is $T_1$.


I have to get a regression model for a dataset, and it seems that the best fit is obtained by log transforming the outcome, so that I simply applied the least squares on the trasformed response vector.  $ \hat{log}({Y}) = \hat{f}(\bf{X}) = \hat\beta_0 + \bf{\hat\beta}^TX$   A prediction with this model estimates $E[log(Y)|X]$, which is NOT the same as a generalized linear model (log-linear), that estimates $log(E[Y|X])$.  In the latter case, if I wanted to get the vector of the estimated outcomes, I would simply compute $\hat{Y} = exp(\hat{f}(X)) = exp(log(E[Y|X])$.  Is there a way to retrieve $\hat{Y}$ in my case?  SOLVED: The difference between the two cases is that in the latter you get $E(Y|X)$ simply by exponentiating the mean of the normal distribution, while in the former you need to consider the mean of the associated lognormal. Multipling $exp(\hat{f}(X))$ by $exp(\frac12\hat{\sigma}^2) = exp(\frac12MSE) $ corrects the bias.

I've obtained a multiple linear regression model in the form $$ \mathrm{log}(Y) = \beta_0 + \beta_1x_1 + \dots + \beta_4x_4 + \beta_5x_1x_2 + \dots + \beta_{10}x_3x_4 + \beta_{11}x_1^2 + \dots + \beta_{14}x_4^2  $$ from the model I've obtained some contour plots that, for a more immediate interpretation, I've back transformed in original units (using $10^{\tilde{y}}$).  Now my question is: do I need to back transform also the model parameters, the confidence intervals of the parameters themselves and the interval of prediction for new responses? How?  I think that would be nice to back transform at least the RMSEP and RMSE in order to obtain an estimate in original units of the mean error associated with the model in prediction and in fitting. How?


I need to average a set of n rasters using gdal or some other GRASS module. What command exists for this purpose?

I have created thousands of png tiles using ArcGIS and have merged groups of them into large jp2 files for serving via GeoServer. I need to flatten these to a single band so that I can apply a colour map to achieve transparency.   is similar but the suggested tool  "Composite Bands tool in arctoolbox" only merges single band to 3 band. I need the reverse!  This is based on the following question   I have arcgis 10.1, qgis/gdal, erdas imagine and global mapper.


When to use function reference such as  void (&fr)() = foo; fr();   instead of function pointer such as  void (*fp)() = &foo; fp();   Is there something function pointer can't do but function reference can?

So I was just working with function pointers and I remembered that you could do this:  void Foo() { }  int main() {     void(& func)() = Foo;      func(); //::Foo(); }   The obvious advantage being that references reference valid objects (unless they're misused), or functions in this case.  The obvious disadvantages being that you can't store an array of references and can't use them for member function pointers (at least as far as I can tell).  My question: does anyone use them (i.e., function references, not function pointers), and if so, in what scenarios have you found them useful/helpful?  The only place I can see them being useful off the bat is binding a reference to a certain function when working with conditional compilation.


Today I'm dealing with the following problem:    Is there some way I can get rid of these without spending my entire day clicking, short of Homer's Drinking Bird?     Note: This is not a duplicate of , because the notifications in my question aren't shown at all in the Notification Center, and thus the solution in that question doesn't work for this question.

I have notifications in the OSX Notification Center, as for most of my apps I am using the setting, "Show in Notification Centre: 10 Recent Items" This is a good setting but rather than have a very full Notification Center, I would still like to clear it from time to time with 1 click.  I am using Yosemite 10.10.3


What is the difference between the following two sentences? The first one is in present simple tense and second one is in future simple tense but the difference in the meaning is not clear.  We fly to Paris next week.   We will fly to Paris next week.

"I go to school tomorrow" to imply that I will attend school tomorrow. Is the aforementioned expression within inverted commas correct?


My Launcher and Panel are gone in Ubuntu 14.04. I have already tried:    Update my software Reinstall nvidia drivers Play with confizconfig Reset Unity   None of those worked, similar to other threads, the Guest account looks alright while mine does not.

When I login, nothing happens.   I am presented with my desktop wallpaper.    No Dash, no Launcher, nothing.


so i changed my name a little while a ago. About a week; and i just want to play minecraft so i open up the launcher log out then back in for my account to update but it says the username or password is incorrect so i tried again and again. still didn't work! then i went onto the minecraft website tried to log in it didnt work. note that i didn't change my password or email just my Minecraft IGN so then after almost an hour of trying to get it, i just changed my email to see if that would work... but still nope! at that point i gave up and posted here.   How can I regain access to my account?

I tried to log into Minecraft today to find that my password isn't working. I tried to change it, but I can't login to my email because I forgot the answer to my security question. I tried changing the email to a different one, but that didn't work for some reason (it kept saying "invalid email"). I don't have my transation ID because I forgot which credit card I used.  Does this mean that I have to buy a new Minecraft account?


After updating to version 63 I have lost many hours figuring out what happened.  I really don't care if it is a valid TLD and I don't want to use .test.  So what are the ways around it? They did not include any settings for this.

I had something set up wacky in our DNS setup which is now resolved. The remaining problem is that chrome has cached the incorrect setup. Specifically, when using Chrome http://example.com is now redirecting to https://example.com (naked domain), which is not valid/supported.  http://example.com SHOULD redirect to http://www.example.com and then force https://www.example.com. But on a handful of browsers (including mine) this doesn't happen because of some funky Chrome caching. I tried going to “Privacy -> Clear Cache” but it had no effect.


On the RPG stack exchange, this question specifically:   I was able to answer the question 10 minutes after it had been closed.  I had begun typing my answer before the question was closed, but during the time that the question was closed, my laptop was hibernating while I relocated to a different room. When I brought it back up, the question gave no indication that it was closed, and it accepted my answer when I submitted it.  Assuming the Stack uses sockets to communicate with machines, it appears that, on a Socket Reconnect, updates are not being pushed and there is no second-level check on the server before accepting an answer.

Question:   Answer:   The question was closed at 11:57:57 (according to the hover-over-"x-mins-ago" bar) and the answer was posted at 12:16:35. It's a fairly lengthy answer, so it's possible that it was started to be written before it was closed but I swear I've started to answer a question then I got a banner along the top saying "this question has been closed" and the answer was no longer post-able.


In a campaign I'm currently in, I want to give my owl that I tamed (the DM allows taming wild animals) a ring of spell storing so it can cast spells. However, before I do so, I wanted to ask: Is there anything mentioned about needing a high enough Int to attune or use magic items? Or can you use them no matter how low your Int is? From what I can find, it seems to only require that the creature spends a short rest focused on the item, but I may be missing something.

We have previously determined that  or  can attune to magic items, but one of those is a sapient creature, and the other "always obeys your commands".  A paladin's steed (per the Find Steed spell) is also 'unusually intelligent' and falls within the score range for sapient creatures.  But what about a regular old animal? If my ranger has a wolf companion, can he make that wolf attune to, say, an Amulet of Health? According to the Beast Master archetype, a companion animal "obeys your commands as best it can".  Is spending an hour 'focused only on the item' (as required for attunement) something a beast can manage?  Or what if it's not an Animal Companion, but just a riding horse, a pet dog, a trained magpie?  I know, probably this is going to be down to the DM to determine, but is there any guidance we can use to help decide whether my cat can attune to an item, and whether rubbing it with catnip would help?


Below is a photo taken by me:   Below is a photo I found on internet:   There are some visible differences between the two. One is dull and the other has visible blacks and whites. I feel I need to study the meaning of some technicalities for BW conversion.   I can't make out what I have done wrong? What the differences between in BW conversion of these two photos?

When I look at the black and white photographs from professional photographers, I notice that they have a special look. Not a specific style—obviously each photographer has her own style—but a look which make them different from similar color photos, a special feeling, which makes them shine specifically as black and white and makes color irrelevant.  When I convert my own photos to black and white in Lightroom, they don't have any special look. They just look like any other of my photos, simply converted to black and white. I imagine that there are two reasons for that:   Some scenes are better for black and white. Talented and/or experienced photographers know which scenes would be beautiful in black and white, and shoot specifically those scenes. Moreover, they know how to adapt the scene itself and the lighting to black and white (for instance by not relying on the color contrast itself).  In my case, I don't think much about shooting for black and white. It comes only in post-processing, when I either think that the photo will look great in black and white (and very often, it doesn't), or I find the colors to be poor and turn the photo to black and white (which actually doesn't make the photo any better). Post-processing is much more complex than clicking on black and white button in an app. It involves not only adjusting black and white mix (i.e. raising or lowering the lightness of specific colors), but doing lots of other adjustments.  In my case, I do black and white mix, but other adjustments I do are similar to what I would do for a color photo: actually, I may even do them on a color photo, and only then turn it to black and white.   So, what should I take in account if I want to have decent black and white photographs? Are there specific techniques, tips, tricks or warnings for someone who usually shots in color and wants to start black and white photography?  Let me show some examples. Are those scenes not great for black and white photos in the first place? Or can they be salvaged through proper post-processing?  1.  First, a poorly done photo from Scotland with dubious composition and very poor colors that I was unable to correct in Lightroom.  The same image in black and white isn't much better. The difference between the trees and the grass on the hill is barely visible. Houses on the hill fade with the sky much more than in the original version.      2.  Here's a photo of a cute pet.  In black and white, the gap between the mouse's ear and the background is barely visible. There is absolutely no benefit compared to the original.      3.  Finally, an example of a much more contrasty picture. The black and white version is weird, since the lack of color makes it difficult to understand whether the soil is the actual sand or something else. I find the sky to be weird as well, and making the blue channel darker or lighter in Lightroom haven't changed that.


I need change background image url in .slide class using jquery. My HTML code like below.  It looks like  home page slider.

Have your own motorcycle? Want to be your own boss?

Work whenever you are free

Make enough money

Share your ride

Sing up with GOMO
           <form action="" method="post">
               Your Name               <input type="text" class="form-control input-lg" id="exampleFormControlInput1" name="rider_name">

               Your Phone Number               <input type="text" class="form-control input-lg" id="exampleFormControlInput1" name="rider_mobile">

               Vehicle Type               <select id="inputState" class="form-control input-lg" name="vehicle_type" required>                 <option selected value="Car">Car</option>                 <option value="Bick">Bick</option>                 <option value="Bicyclek">Bicycle</option>               </select>

                 <button id="home_submit" type="submit" class="btn btn-default">SEND</button>

           </form>

     I need change background image url in .slide class using jquery. My HTML code like below.  It looks like  home page slider.

My DOM looks like this:

   When someone clicks on an image, I want the image src to change to  where x represents the image number 1 or 2.  Is this possible or do I have to use CSS to change the images?


Let $A,B$ be two sets.  Is there necessarily an injection from $A$ to $B$ or an injection from $B$ to $A$ ?

Let $A,B$ be any two sets. I really think that the statement $|A|\leq|B|$ or $|B|\leq|A|$ is true. Formally:     $$\forall A\forall B[\,|A|\leq|B| \lor\ |B|\leq|A|\,]$$   If this statement is true, what is the proof ?


So here is the code that uses x inside a function.   x = 1 def f():     y = x     x = 2     return x + y print x print f() print x   but python is not going to look up the variable out of function scope , and it results in UnboundLocalError: local variable 'x' referenced before assignment . I am not trying to modify the value of global variable , i just want to use it when i do y=x.   On the other hand if i just use it in return statment , it works as expected:  x = 1 def f():   return x print x print f()   Can some one explain it why?

The following code works as expected in both Python 2.5 and 3.0:  a, b, c = (1, 2, 3)  print(a, b, c)  def test():     print(a)     print(b)     print(c)    # (A)     #c+=1       # (B) test()   However, when I uncomment line (B), I get an UnboundLocalError: 'c' not assigned at line (A). The values of a and b are printed correctly. This has me completely baffled for two reasons:   Why is there a runtime error thrown at line (A) because of a later statement on line (B)? Why are variables a and b printed as expected, while c raises an error?   The only explanation I can come up with is that a local variable c is created by the assignment c+=1, which takes precedent over the "global" variable c even before the local variable is created. Of course, it doesn't make sense for a variable to "steal" scope before it exists.  Could someone please explain this behavior?


What is the difference between the following two sentences?     I came direct to my residence from the airport.      I came directly to my residence from the airport.

happening or done without involving other people, actions, etc. in between and we can form it into an adverb "directly"  Ex: look directly into his eyes  but "directly" is also an adverb  : without involving other people  are "Look directly into his eyes" and "Look direct into his eyes" the same?  I would think "Look direct into his eyes" is not common or strange but I am not sure although you can see 800 results when googling "Look direct into his eyes"


I have a relatively new price aggregation website (online for about one month). Part of it was also adapted (custom header/footer) and included into an older site, on a different domain, which already has a Google PageRank,  and domain authority.  In order to prevent duplicate content and to promote the main website, the integration contains canonical-url links on the old website pointing to the respective website pages on the new domain.  From a SEO point of view will any rank juice be passed from the older website and domain (which contains the integration) to the new one through the canonical links? Or is it better to just add "dofollow" links from the integration to the main website?

One of the issues with duplicate content is that links can be split across several versions of your page, it was my understanding the a 301 redirect is really the only option for retaining some of the link juice, however, looking at some answers here and on other forums it looks like some people believe the canonical tag will have the same effect as a 301 (in the search engines eyes).   Does the canonical tag tell the search engines that the links pointing to duplicate pages should count for the original or does it simply tell them which version of the page you want indexed?


To extend the heading a little bit further. There are 100 holes ordered from min to max (min-hole with minimal radius, max-hole with maximum radius). There are two balls given which are to be used to find the perfect hole (matching hole). There is only one hole which matches perfectly with both balls (both balls are the same size as the matching hole which has to be found) . Find the shortest possible way to find the matching hole.  Note: if the ball in the whole is too big and the ball drops, you are loosing a ball.  What I've tried:   The easiest way is to insert a ball in the min-radius hole and then the second ball to the hole+1 until one ball goes away by falling inside the whole which means that the hole-1 is the matching hole if of-course the given ball does not match the most widest hole (max hole). The second thing that I would apply is a form of binary search algorithm by reducing the wholes drastically but then I would need to measure the radius of the holes after dividing the set (and the ball radius), however I'm not sure if this is allowed.   I believe there is better attempt to solve the problem any suggestion are greatly appreciated.

You have two identical eggs. Standing in front of a 100 floor building, you wonder what is the maximum number of floors from which the egg can be dropped without breaking it. What is the minimum number of tries needed to find out the solution?


It's well-known that $$\max(a,b)=\frac{a+b+|a-b|}{2}.$$  Is there a (good) generalization to several variables?  Of course $\max(a,b,c)=\max(a,\max(b,c))$ and so $$\max(a,b,c)=\frac{a+\frac{b+c+|b-c|}{2}+|a-\frac{b+c+|b-c|}{2}|}{2}$$ $$=\frac{a+0.5b+0.5c+0.5\left|b-c|+|a-0.5b-0.5c-0.5|b-c|\right|}{2}$$ but I'd like a form that shows the natural symmetry better and which doesn't have so many operations.  This is a practical problem working on a system which has an absolute value operator but no maximum and not much ability to execute conditional statements, but to be honest the real reason I'm interedted is an attempt to beautify something that is seemingly ugly.  For the practical side I need 5-10 arguments and it's acceptable to assume that all arguments are at least 0, though of course it would be much more satisfying if this latter assumption was not needed.

As we saw , the minimum of two quantities can be written using elementary functions and the absolute value function.  $\min(a,b)=\frac{a+b}{2} - \frac{|a-b|}{2}$  There's even a nice intuitive explanation to go along with this: If we go to the point half way between two numbers, then going down by half their difference will take us to the smaller one. So my question is: "Is there a similar formula for three numbers?"  Obviously $\min(a,\min(b,c))$ will work, but this gives us the expression: $$\frac{a+\left(\frac{b+c}{2} - \frac{|b-c|}{2}\right)}{2} - \frac{\left|a-\left(\frac{b+c}{2} - \frac{|b-c|}{2}\right)\right|}{2},$$ which isn't intuitively the minimum of three numbers, and isn't even symmetrical in the variables, even though its output is. Is there some nicer way of expressing this function?


I hope I'm not asking something preposterous but I'd like to understand how 120V USB power adapters work so that I can think about how to put one onto a board that I'd like to have made. The main problem is I don't know what to call them other than "USB power adapter". Can you tell me what components are involved and what resources I can look at to learn more? Thanks.

I'm designing a project that controls 110VAC (plug in, socket out), and also has a microprocessor inside.  I'd really like this project to not need a wall wart to get it's 5V, so I want to include a small DC power supply inside.    Apple's USB power adapter looks like a great small design that I can fit inside my case.  I'm guessing this is a switching power supply but I can't find any teardowns or schematics anywhere.  Does anyone know how this thing works?  I know I could make my own 110V->5VDC supply from a bridge rectifier and some caps, but I'd like to also be super safe.  What's in the Apple brick?


I'm having trouble understanding the output of a piece of python code. mani=[] nima=[] for i in range(3)     nima.append(i)     mani.append(nima)  print(mani)  The output is [[0,1,2], [0,1,2], [0,1,2]]   I can't for the life of me understand why it is not [[0], [0,1], [0,1,2]]  Any help much appreciated.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


If so, which is/are the best site(s) to get them?  // I already found .  Any other suggestion?

This might already be answered, but I can't find it.   I am getting a bit bored of the traditional purple feel of unity and I would like something new. Where can I find more Unity themes?  I have already tried synaptic, but could not find anything. I would rather avoid people's personal PPA's.


Good day! Explain it to me please:)  Is is right to say:  Five-storeys houses  or  Five-storey houses?  Thanks a lot!

So I was taught that you should almost always use singular form of an adjective instead of plural form. But recently, I've seen people using plural form and it sounds quite weird and I don't know if it is correct.  For example,   "Salary tax" instead of "Salaries tax" "Office supplies" instead of "Offices supplies" "Product demo" instead of "Product demo"   In the above cases, the word "Salary" is used as an adjective to describe the type of "tax", so it will be in singular form. But I saw people using salaries tax and not sure if it is grammatical.  So my question is if there are any general rules on how to use the singular/plural form of an adjective?


If I throw a stone in the air,how does earth know that it(stone) needs to be pulled. My point is are the rules of physics contained inside every single particle? Or is there a central body checking the conditions every single frame and then doing the respective actions?(here frame means periodic update of the universe just like in computer graphics). My question is kind of silly, but I hope that there is answer somewhere.

I was watching a waterfall in the Austrian Alps. There were thousands of water droplets falling down, splattering on the stones below. I thought - how does nature find out so quickly where each droplet of water should go? To find out what happens to a falling droplet of water, one can use the laws of motion and calculate the trajectory. To calculate, one needs some amount of time, some machine (the brain, computer) and some energy to feed the machine. Does it make sense to ask what is the equivalent of this computation in nature? How does nature find out so quickly how things should move? More generally, to find out how anything should happen? Where is the "calculation" in nature? There's no room or energy for a machine in the particles that make up things.


Well, um, uh, long story short, I have holes in one of my interior doors.    Full picture of door here:   What is the best way to go about repairing it? Should I go about this similar to fixing holes in drywall? Should I find replacement wood to go into the holes? I am concerned about the amount of missing material. I am not sure if tons of spackle paste would work well as the other question's answer states.

My son sometimes has a temper, and has been known to hit his door when sent to his room. He has actually done so enough to punch a bit of a hole in it. I'm trying to figure out what might be doable to fix the door. Here is a photo of it:    As can be seen, there is a crack on the left that is visible and slightly dented in, and the center/right hole is actually pressed in pretty good. The punched hole is approximately 6 inches in diameter.   I'm going to make my son pay for the repairs from his allowance, and as that is limited, I am hoping for a fairly quick/inexpensive solution.  Any ideas as to what can be done?


I'm reading file content and take string at exact location like this   string fileContentMessage = File.ReadAllText(filename).Substring(411, 3);   Output will always be either Ok or Err  On the other side I have MyObject which have ContentEnum like this  public class MyObject      {       public enum ContentEnum { Ok = 1, Err = 2 };               public ContentEnum Content { get; set; }     }   Now, on the client side I want to use code like this (to cast my string fileContentMessage to Content property)  string fileContentMessage = File.ReadAllText(filename).Substring(411, 3);      MyObject myObj = new MyObject ()     {        Content = /// ///,     };

What's the best way to convert a string to an enumeration value in C#? I have an HTML select tag containing the values of an enumeration. When the page is posted, I want to pick up the value (which will be in the form of a string) and convert it to the corresponding enumeration value. In an ideal world, I could do something like this: StatusEnum MyStatus = StatusEnum.Parse("Active");  but that isn't a valid code.


My last interview went like this!  EDIT:  The linked question seems to be answering the question but its not. I have already in the below code-snippet mentioned that. The question is other than that, whats the difference?.  What is the difference between ArrayList and List<object> ?  (They were asking specifically about List<object> not List<T>)!   My explanation is we cannot use ForEach extension method for ArrayList and ArrayList is a non-generic functionality.      ArrayList arrayList = new ArrayList();     List<object> listObjects = new List<object>();      foreach(object item in arrayList)     {         Console.WriteLine(item);     }      listObjects.ForEach(item => {         Console.WriteLine(item);     });    I explained this to my interviewer but she seemed to be expecting something else. Anything  other than that?

I saw this reply from Jon on :     If you want a single collection to   contain multiple unrelated types of   values, however, you will have to use   List<object>   I'm not comparing ArrayList vs List<>, but ArrayList vs List<object>, as both will be exposing elements of type object. What would be the benefit of using either one in this case?  EDIT: It's no concern for type safety here, since both class is exposing object as its item. One still needs to cast from object to the desired type. I'm more interested in anything other than type safety.  EDIT: Thanks Marc Gravell and Sean for the answer. Sorry, I can only pick 1 as answer, so I'll up vote both.


Basically, I do not want to post duplicate questions, so I always do a search in the top right hand first, sometimes I learn a lot and spend about 30 minutes+ reading up on similar results that are very interesting, however not the exact question I want.  So, at this point I go to Ask Question and after typing a title, to my shock, the exact question I want answered pops up, despite putting the same terms into search.  Am I alone here, or is there some scope in the future of a sort of "Ask Jeeves" type search where you actually write the question and get the same results as I do in the related questions?

When I search for similar questions that I am going to ask, I usually can't find anything through the search box on Stack Overflow. But when I enter my question on the "Ask Question" page, the questions suggested through the "Questions with similar titles" box are usually relevant. Do you experience the same thing?


I have installed a ubuntu 14.04 in my company, and I want to block websites in my browser Firefox/Chorme, but how can I do this?   Thanks!

I bought my kids a PC and installed 12.04 (Unity) on it.  The bottom line is, I want my children to use the computer unsupervised while I have confidence they cannot access anything inappropriate.  What I have looked at:  I was looking at Scrubit a tool which allows me configure my wifi router to block content and this solution would also protect my other PC and mobile devices.  This may be overkill as I just want the solution to work on one PC.    I also did some Google searches and came across the application called .  My experience of OSS is that the best solutions frequently never appear first on a Google search list and in this case I need to trust the methods therefore my question is very specific.   I want to leverage your knowledge and experience to understand What is the best way to restrict adult content on 12.04 LTS as this is important to me.  It maybe a combination of things so please don't answer this question "try this or that", then give me some PPA unless you can share your experience of how good it is and of course if there are any constraints.


If I have an infinite cylinder with radius $R$ and a surface density of current that varies with time, I can use ampere's law to calculate the magnetic field. My question is why is possible to ignore the displacement current when calculating the magnetic field, in this case?

I know how to calculate the magnetic field due to current inside the solenoid.  Obviously, when the current is varying, then the magnetic field will be time dependent.  By the 3rd Maxwell's equation, an electric field will be created.  I'm wondering that, why can I still use Ampere's law to calculate the magnetic field within the solenoid? (in fact, can i?)  I thought that the time varying electric field will also produce a magnetic field, meaning that the total magnetic field is not just that calculated from Ampere's law, but the sum of that calculated from Ampere's law and that produced by time varying electric field.


I remember reading, recently (2018 or so) a short sci-fi/horror story online about a tourist visiting a utopian island, the catch was that a tourist could only stay six days, as something horrible would occur on the 7th of each week, as the price for this utopia's existence.  While there, there were 6 days of carnivals and festivals, while I seem to recall that those who lived through the 7th day were immortal, or that you didn't age on the island?  The main character (male) had met a girl while visiting, and decided to abandon his ticket back to the mainland.  There was a particular scene I recall at the striking of midnight of the 7th day, the man and this woman were in a club when things start to go awry, teeth cracking and blood pooling on the floor.  After the 7th day everyone recovers however, and the cycle begins again, no one discusses or even acknowledged the previous day, as a mutual agreement.  Some of the scenes from the 7th day I believe talk of radio chatter and modern weaponry, so the book is from the late 20th century I would imagine.

I'm looking for a short story or novella about an idyllic, utopian society with a hidden dark side: periodically (every week or month) its inhabitants would descend into madness, violently destroying everything around them and brutally murdering each other. This continued for a day or so, and when it ended, the ordeal was somehow magically undone, with even the dead returning to life. Then everyone would be left with only their memories of the experience, to enjoy their perfect society until the next time around.  The society was some kind of city-state with a vaguely Mediterranean feel, maybe on an island or isolated peninsula. There was a strict rule about visitors, but I can't quite remember what it was: either they had to leave before the violence started unless they agreed to immigrate permanently, or they couldn't leave until they had experienced it at least once.  The story was posted online on what looked like someone's personal website (possibly the author's), split into a separate page for each chapter. I read it sometime in the last several years, and I feel like the writing style reminded me of Jorge Luis Borges.


I am setting up a disaster recovery strategy for two 2012 servers DB1 and DB2 in one location and may be later I plan to set them in different locations, I want DB2 to take control incase of of DB1 failure. They are installed with MySql 5.5 database application and for now DB2 has no data.  How can can I replicate and synch these two servers? and create backups from DB2?

We are in the process of implementing a new CMS (Drupal 6.x) that runs on MySQL. We have two data centers -- primary and secondary -- with known latency between them. We're unsure which version of MySQL we will run ... either Community or Enterprise, but that is a TBD. Looks like we will be running the InnoDB engine, OS is going to be RedHat EL 5.5 The primary servers are going to be active, while the secondary will be passive or hot stand-bys.   I would like to implement replication, high availability and automated failover in MySQL across the two data centers.   After a failover to the secondary servers, when we fail-back to the primary servers, we'd like to have data synched from the secondary DB to the primary DB quickly and completely so that we can continue to serve content from the primary servers.  I am interested in knowing what technologies/tools/best practices can be used to solve/address these issues. Also, any gotchas or ah-ha moments would be much appreciated as well. I've read up on MySQL replication, clustering, and at some 3rd party tools like Tungsten and Dolphinics, but I a unsure what the is best course of action.  Thank you for your time!  KM


I'm trying in my game to have camera rotation speed idependent of fps. For keyboard it works without problems but not for mouse movoment. At 60 fps it works good but at 200 for example rotation is to slow.  mouse_dif is difference since last frame in pixels. Maybe thats a problem too, bigger screen resolution will rotate faster then smaller.  My code:  const float rot_speed = u.GetRotationSpeed(); // returns 5.f float val = 0;  if(allow_input == ALLOW_INPUT || allow_input == ALLOW_MOUSE)     val += float(mouse_dif.x)/200;  if(val > rot_speed*dt)     val = rot_speed*dt; else if(val < -rot_speed*dt)     val = -rot_speed*dt; u.rot += val;   How can I make it fps independent?

Should a game loop be based on fixed or variable time steps?  Is one always superior, or does the right choice vary by game?  Variable time step  Physics updates are passed a "time elapsed since last update" argument and are hence framerate-dependent.  This may mean doing calculations as position += distancePerSecond * timeElapsed.  Pros: smooth, easier to to code  Cons: non-deterministic, unpredictable at very small or large steps   example:  while( game_is_running ) {     prev_frame_tick = curr_frame_tick;     curr_frame_tick = GetTickCount();     update( curr_frame_tick - prev_frame_tick );     render(); }   Fixed time step  Updates might not even accept a "time elapsed", as they assume each update is for a fixed time period.  Calculations may be done as position += distancePerUpdate.  The example includes an interpolation during render.  Pros: predictable, deterministic (easier to network sync?), clearer calculation code  Cons: not synced to monitor v-sync (causes jittery graphics unless you interpolate), limited max frame rate (unless you interpolate), hard to work within frameworks that assume variable time steps (like  or )   example:  while( game_is_running ) {     while( GetTickCount() > next_game_tick ) {         update();         next_game_tick += SKIP_TICKS;     }     interpolation = float( GetTickCount() + SKIP_TICKS - next_game_tick )                     / float( SKIP_TICKS );     render( interpolation ); }   Some resources     —allegedly a reason  is frame-locked to 60fps? Flixel requires a variable timestep (I think this is determined by Flash) whereas  allows both types.  suggests it uses constant time steps.


I have a folder of files.  I would like for the system to check this folder every X minutes to see if any of the files have changed and, if so, to then run a script that I've written in python.

I'm looking for a CLI tool which will watch a directory and spit out the names of files that change in real time.   some_watch_command /path/to/some/folder | xargs some_callback   I'm aware of inotify (inotify-tools?) and it seems to be what I need, but I need something that is both Linux (in my case Ubuntu) and OSX compatible.  It doesn't need to be lightning fast, but it does need to trigger upon changes (within a second is reasonable). Also, I don't necessarily need the exact CLI program mentioned above.  If some underlying tech exists and is easily scriptable on both platforms that would be great too.


I took out a Pork Roast that was completely frozen solid (double wrapped) and set on counter. Forgot about it until 6 hours later but it was still frozen. Just started feeling a bit soft on top but not deep - just barely - just surface. Is it still safe to eat? I put it in fridge overnight to complete the thawing process.

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


My freezer went without power for 70 hours while we were out of town.  The power was restored before we returned and refroze everything.  The unit was full and did have some solid ice packs within.  Is anything safe to consume in this freezer?

We were on vacation for a week. The neighbor said we were out of power the whole time.  We have a chest freezer full of beef. It thawed but remained in the freezer unopened the whole time. Is the meat bad if it is thawed but still cold? Can we refreeze it and eat it?