On Wikipedia, it says that $\lim_{n\to\infty}(1+\frac{1}{n})^n = e$ :     It [e] is approximately equal to 2.71828,[1] and is the limit of (1 + 1/n)n as n approaches infinity, ... ()   When I evaluate $(1+\frac{1}{n})^n$ for $n = 10^8$, I get approximately $2.718281798347$ which indeed is pretty close to $e$.  But when I try to "solve" the limit using the laws of limits, I get  $$\lim_{n\to\infty}\left(1+\frac{1}{n}\right)^n = \left(\lim_{n\to\infty}\left(1+\frac{1}{n}\right)\right)^n$$  because of the power law  $$ = \left(\lim_{n\to\infty}(1)+\lim_{n\to\infty}\left(\frac{1}{n}\right)\right)^n$$  because of the addition law  $$=\left(1+0\right)^n = 1$$  but that would mean that $e=1$, which is obviously not true.  What am I missing / doing wrong?  Thanks in advance.

I am trying to identify what the flaw is exactly when reasoning about a limit such as the definition of $\mathbf e$:  $$ \lim_{n\rightarrow \infty}\left(1+\frac{1}{n}\right)^n={e} $$  Now, I know there are ways of proving this limit, such as by considering the binomial expansion of $(1+\frac{1}{n})^n$ and comparing that to the Maclaurin series of $e$. So to make this clear, I am not looking for a proof of the limit definition of $e$.  I tried searching for "limit laws/rules" but none of the rules I found described the above case. Hence, I am looking for a specific rule (or perhaps a certain perspective) that will help me realize why the above does not in fact evaluate to 1.  My train of thought is as follows: at a first glance, if I wasn't already familiar with what the limit evaluates to, I probably would evaluate the expression inside the brackets first, and then apply the limit to the power. So, $$\displaystyle\lim_{n\to\infty}\frac{1}{n}=0\quad\text{and then}$$  $$\displaystyle\lim_{n\rightarrow \infty}\left(1+0\right)^n=\lim_{n\to\infty}1^n=1$$  Why is my reasoning flawed?


This question is about why the passport number changes? while the  asks if the passport number changes?.  Looking at answers to , it seems that most passport numbers change upon renewal. Not all do though, as I have recently discovered. Apparently, Australian ones do change in some cases.  Why does the passport number change? Is there a rationale for this?  It seems that some organization created rules for passports to change when reissued, but again what are the advantages of this, compared to its disadvantages?

I'm travelling soon but need to renew my passport.  Given that I have to provide my passport number to the airline to book a flight, I was wondering if my passport number would change if I renew it.  Or would the number stay the same and the expiry date just change?  I'm asking specifically as an Australian citizen, although I suspect a 'common' answer (if there is a general way this works) might be useful too.


Evaluate $$\frac{\sum_{n=1}^{99}\sqrt{10+\sqrt{n}}}{\sum_{n=1}^{99}\sqrt{10-\sqrt{n}}}$$   Both the top and bottom do not telescope and and last and first do not add up to something nice, so I do not know how to proceed. Thanks!

Here is the question:     $$\frac{\sqrt{10+\sqrt{1}}+\sqrt{10+\sqrt{2}}+\cdots+\sqrt{10+\sqrt{99}} }{\sqrt{10-\sqrt{1}}+\sqrt{10-\sqrt{2}}+\cdots+\sqrt{10-\sqrt{99}}} = \;?$$   ()  I think we need to simplify it writing it in summation sign as you can see here:  $$\frac{\sum\limits_{n=1}^{99} \sqrt{10 + \sqrt{n}}}{\sum\limits_{n=1}^{99} \sqrt{10 - \sqrt{n}}}$$  or in Wolfram Alpha input in comments.  I can compute it too! It's easy to write a script for this kind of question. I need a way to solve it. How would you solve it on a piece of paper?


I'm trying to prove: $\lim_{t\rightarrow 0} \dfrac{t}{\ln(1+t)}=1$ without use L'Hospital and derivate, because I still do not define derived from the logarithm, is there any way to prove it by the definition epsilon-delta? So far I have only defined $\log$ as the inverse function of $a^{x}$ and particular case $a = e$ although the latter is proposed very weak, it may be improved later using integrals, some help thanks in advance.

$$\lim_{x\to 0} \frac{\ln(1+x)}x$$  The process I  want to take to solving this is by using the definition of the limit, but I am getting confused. ( without l'hopitals rule)   $$\lim_{h \to 0} \frac{f(x+h) - f(x)}h$$  $$\lim_{h \to 0} \frac{\frac{\ln (1+x+h)}{x+h} - \frac{\ln(1+x)}x}h$$  $$\lim_{h \to 0} \frac{x\ln(1+x+h) - (x+h)\ln (1+x)}{hx(x+h))}$$  At this point I get confused because I know the answer is $1$, but I am not getting this answer through simplification of my formula.


What Versions Of Ubuntu/Debian or Ubuntu/Debian Based Disros Can Run On A iMac G3?

I have an old PowerMac G4 that I installed Lubuntu 16.04 on a while ago. I've been getting notifications in the terminal that 18.04 is available to upgrade, but the upgrader fails to run, saying that the package ubuntu-minimal is not available. I haven't seen any ISOs for PowerPC available, and ports.ubuntu.com doesn't have any bionic distributions available for architecture  powerpc. But while searching I found  that suggests that there is/was a version of Ubuntu 18.04 for PowerPC. Is this just a pre-generated page, or is there somewhere I can get Ubuntu Bionic for PPC?


In , it states in the 3rd paragraph of the background information section that, "As stored material [for replicating replacement mines] begins to run out the mines have a zero-point extraction system for matter replenishment." It does not, however, explain what a zero-point extraction system is. Is there any explanation for what this is, or how it works, and has it ever been seen elsewhere in the Star Trek universe?

Standard replicators are able to replicate mundane materials and smaller not-too-complex machines. At one point, under the influence of a Cardassian anti-riot program, the replicators in DS9 are magically able to produce something like a self-targetting automatic phaser gun.  Normally, for more complex tasks, such as "building a powerplant" or "making major parts of a starship", very special and rare "industrial" replicators are needed. Apparently, an entire planet normally doesn't have more than half a dozen of these, and they are valuable enough for super secret security measures so the Maquis won't steal them (which they do anyway).   In either case, replication is the process of turning energy into matter.  In addition to their main power supply and thrust, the self-replicating mines contain a standard photon torpedo warhead, which means that they are able to release a considerable amount of energy (which is "gone" after the explosion) from a matter/antimatter reaction. The energy, and of course the antimatter must come from somewhere (regardless of the energy needed, can a replicator replicate antimatter at all?).  It seems improbable (if not impossible) that self-replicating mines could work at all. If you were able to replicate an energy cell containing the same amount of energy as the original one plus a considerable amount of matter/antimatter plus some other stuff, like a cloaking device then you would have the most perfect perpetuum mobile imaginable.


I'm really confused with the question below.     A phone number is a 7-digit sequence that does not start with 0.   (a) Call a phone number lucky if its digits are in non-decreasing order. For example, 1112234 is lucky, but 1112232 is not. How many lucky phone numbers are there?   (b) A phone number is very lucky if its digits are strictly increasing, such as with 1235689. How many very lucky phone numbers are there?   I have learnt that to determine if a question is asking for permutations or combinations we see if the order matters. For part a) it's talking about the order of these numbers and how many of these exist. In my head, permutations pop up and I would say the first position has 9 possibilities and so do the rest (if repeated). This is my same logic in part b). However, they are wrong and I do not understand how to proceed with this question. Please give some helpful tips when solving such problems.

I stumbled upon a question given like:  Let $m$ and $n$ be two integers such that $m \geq n \geq 1$.   Count the number of functions $$f: \{1, 2, · · · , n\} \to \{1, 2, · · · , m\}$$ of the following two types:  (a) strictly increasing; i.e., whenever $x < y, f(x) < f(y)$, and  (b) non-decreasing; i.e., whenever $x < y, f(x) \leq f(y)$.  I tried in the following way.  For (a). We can say $f(n)>f(n-1)$ AND $f(n)>f(n-2) \ldots f(n)>f(1)$ (total $n-1$ elements)  Similarly for $f(n-1)>f(n-2), f(n-1)>f(n-3) \ldots f(n-1)>f(1)$ (total $n-2$ elements)...  and $f(2)>1$  Like this $$(n-1) + (n-2) + \ldots + (1) = \frac{n(n-1)}{2}$$  Is this correct?  For (b). Since there's equality, it will be $$n + (n-1) + ... (1) = \frac{n(n+1)}{2}$$  Is my approach correct? Any help is appreciated. Thanks in advance.


I'm Trying to find an example for two non isomorphic,  finitely generated,    residually finite groups $G_1$ and $G_2$ such that there exists $N_1\unlhd G_1$,$N_2\unlhd G_2$ while $G_1/N_2 \cong G_2/N_2$ and $|[G_1:N_1]|=|[G_2:N_2]|<\infty$.  It's my understanding that residually finite is not the same as finitely presented. Thank's in advance to all responders.

I'm looking for an example of $2$ non isomorphic groups $G_1,G_2$  that are finitely generated and presented that have the same finite quotients (up to isomorphism) .  Thanks


I would like to know which font the following image is:    and how to use it in latex. Any ideas? It is not quite Times.

Is it possible to identify the font used in a specific document/picture?  Answers to this question should identify:   Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y").   This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's  tag.


I have a PHP script that is suppose to take values from html form and insert them into a PDO database I do have the tables set. It does not give errors or work.  This is the HTML "form" code:  <form action="latestarticles.php" method="POST">     <input type="text" name="title" value="Title"/>     <input type="text" name="author" value="Author name"/>     <textarea name="content"></textarea>     <input type="datetime-local" name="currentdate" />     <select name="category">         <option value="Sports">Sports</option>         <option value="Local news">Local news</option>         <option value="Technology">Technology</option>         <option value="Business">Business</option>     </select>     <input type="reset" name="reset" value="Reset" />     <input type="submit" name="submit" value="submit" /> </form>   This is the php code latestarticles.php:  <?php if (isset($_POST['submit'])) {     $stmt = $pdo->prepare("INSERT INTO articles (articletitle, articleauthor, articlecontent) VALUES ($_POST['title'], $_POST['author'], $_POST['content'])");      $stmt->execute();      echo '<p> Successful insert </p>';  } else {      echo '<p> You suck at programming </p>';  } ?>   Thank you for all the help!

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


Check if the series $\sum_{n=1}^\infty\frac{1}{n \sqrt[n]{n}}$ converges   I've tried using the Cauchy test and the root test but none of them seems to work with this series and so  I decided to apply the comparison test.   I don't know if what I'm doing right now is correct:   It is know that $$\sqrt[n]n \rightarrow1$$ And so if we take sufficiently large n, $n \sqrt[n]{n} < 2n$ Which implies that $$\mbox{For sufficiently large n} \\\frac{1}{n\sqrt[n]n}>\frac 1 {2n}$$ And so now, by the virtue of the comparison test, I can claim that the series in question diverges. Is it a correct way to do this? If so, is it possible to pick any positive integer greater than $2$ instead of $2$ for this method to work?

We know that $\sum \frac{1}{n^p}$ is convergent for $p>1$. However the series $\sum {\frac{1}{n^{1+1/n}}}$ is apparently divergent since $1+1/n$ tends to 1 as $n$ tends to infinity. But how to prove this? The root test fails expectedly and I haven't been able to find a smaller divergent series for comparison test. Can someone help? Thanks!


I embed an illustration of variables next to the paragraph describing them:  \noindent\begin{minipage}{.48\textwidth}     \indent Lorem ipsum \end{minipage} \hfill \begin{tikzpicture}     … \end{tikxpicture}   You can already see my use of \noindent to avoid the whole textblock being indented. Then I try to explicitely indent the text in the minipage (I still need the first line indentation, like in any other paragraph).  I learned that minipage sets \parindent to 0pt. How can I set it to the value used in the rest of the document? (I would like to avoid setting a specific value that might fit or might not fit the template.)

I have following structure:   \begin{document}  Paragraph1. Paragraph2.  \begin{minipage} Some paragraph1. Some paragraph2. \end{minipage}  \end{document}   How can I make the same spacing between paraghs in minipage section as in plain paragraphs? Would like to make it as macros, in order not to repeat it many times, but this failed:  \let\currentparskip\parskip \newenvironment{minipage_parskip}{   \begin{minipage}{\textwidth}{     \setlength{\parskip}{\currentparskip}   } }{   \end{minipage} }


A problem related to an interesting  Casimir configuration.   I have the following configuration , related to a modified Casimir experiment.  We have two parallel metal plates and an  orthogonal  metal plate connecting the two parallel plates. Note that this is very close to the experimental setup of the original Casimir experiment,  except for the orthogonal plate (connecting the two parallel plates at one end).   I would like to know all the Casimir  forces that exist in this configuration.  For clarification you can see the following   My naive intuition could be incorrect, but my impression is that the asymmetric radiation  pressure due to quantum fluctuations would lead to the emergence of a certain force (parallel to the parallel plates), but I don't know if the QFT / QED calculations justify my intuition (where in fact  these virtual particles are just an intuitive representation of links in Feynman diagrams, linked to terms in infinite perturbation series).       Closely following the arguments in these two papers, that force mentioned above does indeed exist (for the three plate system mentioned above).  I hope somebody here can quickly settle this problem, so I don't spend a long time digging for an answer. Thanks.

A problem related to an interesting  Casimir configuration.   I have the following configuration, related to a modified Casimir experiment.  We have two parallel metal plates and an  orthogonal  metal plate connecting the two parallel plates. Note that this is very close to the experimental setup of the original Casimir experiment,  except for the orthogonal plate (connecting the two parallel plates at one end).   I would like to know all the Casimir  forces that exist in this configuration.  For clarification, you can see the following picture:    My naive intuition could be incorrect, but my impression is that the asymmetric radiation  pressure due to quantum fluctuations would lead to the emergence of a certain force (parallel to the parallel plates), but I don't know if the QFT / QED calculations justify my intuition (where in fact  these virtual particles are just an intuitive representation of links in Feynman diagrams, linked to terms in infinite perturbation series).       Closely following the arguments in these two papers, that force mentioned above does indeed exist (for the three plate system mentioned above).  I hope somebody here can quickly settle this problem, so I don't spend a long time digging for an answer. Thanks.


I created a Transactional SMS Send Definition via REST API (Transactional API), and am able to send SMS via API just fine.  Is there any way to shorten a dynamic link that is passed in to the API via an attribute?  Example: see below - you'll see an attribute called URL that is being passed in to the API call.  What I would like to do is shorten this URL.  We can do this via the UI using the typical, non-transactional way of sending SMS, but I can't figure out how to do this in real time using the Transactional API. Edit: The end to end process looks like this:  Salesforce CRM makes an API call via an Apex class to SFMC's Transactional Messaging API. SFMC receives the API call (JSON payload) and simply executes it (sending the SMS).  There's no AMPScript involved, although, a viable workaround would be for SFDC to make a POST call to a CloudPage instead, and have that CloudPage make the call out to shorten the URL via AMPScript, THEN, pass that into the Transactional Messaging API, but we are trying to keep this as out of the box as possible with no customizations (out of scope). Host: https://YOUR_SUBDOMAIN.rest.marketingcloudapis.com POST /messaging/v1/sms/messages/f4fe74b7-c3c0-4e5a-9f49-b63a641109a2 Content-Type: application/json Authorization: Bearer YOUR_ACCESS_TOKEN  {   "definitionKey": "account-reset",   "recipient": {     "to": "15555551234",     "contactKey": "Astro25",     "attributes": {       "URL": "https://www.asuperlongurl.com/"     }   },   "subscriptions": {     "resubscribe": true   } }

I need to send a link to a CloudPage through SMS with an query param (www.example.com?id=XXXX), which the CloudPage will use to get value from a Data Extension and pre-fill some data to Contacts and ask for others.  This param value is different for each contact and the actual URL is too big, so I want to use Bitly to short this link. I can use AMPScript to create a , but this example is using V3 API, since it's going to be deactivated, I'm making it in V4.    The problem now it's I need to make an request through Bit.ly API with an JSON in request body, inside SMS message.  %%[   var @testID, @cloudpage, @link, @leadId, @bitlyPage, @contentType, @content,       @bitlyToken, @additionalHeaderName, @additionalHeaderValue, @output, @respheader   set @testID = 'XXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX'   set @bitlyToken = 'myToken'   set @bitlyPage = 'https://api-ssl.bitly.com/v4/bitlinks'   set @contentType = 'application/json'   set @additionalHeaderName = 'Authorization'   set @additionalHeaderValue = concat('Bearer ', @bitlyToken)     set @cloudpage = CloudPagesURL(1591,'id',@testID)   set @link = URLEncode(@cloudpage)    set @content = Stringfy({"long_url": @link}) ]%%    %%=HTTPPost2(@bitlyPage, @contentType, @content, true, @output,         @respheader, @additionalHeaderName, @additionalHeaderValue)=%%    Output: %%=v(@output)=%%   Header: %%=v(@respheader)=%%   When I try to run this in Preview and test, I get the following error:      There is an error in your email. Please contact your customer service representative. Error 1: Script SET Statement InvalidAn error occurred when attempting to resolve a script expression. See inner exception for detail. Script Expression: Stringfy MemberID: nnnnnnn JobID: 0 An unrecognized expression appears in a script block.   If I try without Stringfy, I get this error:     Error 1: Script SET Statement InvalidAn error occurred when attempting to resolve a script expression. See inner exception for detail.   How can I send this JSON data in body? or there is another way to make this Bitly link?


I often find myself either zooming, rotating, or panning too slow or too fast How can I get better at this? What options can I do? So far Ive only somewhat solves zoom with Ctrl MMB = slower smoother zoom Ctrl shift MMG = faster zoom but sometimes even the slow zoom is not slow enough, and I cant hold shift for any of the navigation controls to slow it down either. Any thoughts anyone?  Update) Okay so something I noticed when you start zooming with scroll wheel and slow down thats when rotate and pan also slow down if you scroll back out then use Ctrl shift mmb or ctrl MMB to have a faster zoom then rotate and pan will be at the same relative speed i need to be able to control when that "slow zoom" is happening so I can decide "now I want slow zoom" = rotate and pan will also slow down the problem seems to be that I dont have a control of when that slow zoom happens and as a result can get unwanted speed ramps or slow downs in navigation

I often find that I can zoom in to a point, but then cannot zoom any more, even when there is a lot of room to zoom to the meshes on the scene.   This is particularly annoying in the following scenario:  I often land up left clicking on the scene and the 3D cursor shifts there. I use Shift+C to shift the 3D cursor back to the origin. However, this also centers the view on the cursor and shifts the view to show all objects, and sometimes this zooms things way out – at this point, if I try to zoom in, I can zoom in to a point (using the pinch/zoom on trackpad), but then it stops zooming in.   How do I zoom in after that? Is there anything else I am doing wrong in this case?


Is Mental Ray available for Blender? Are there any other production quality render options?

Since asking for tutorials, videos, resources, links to other content or downloads is considered off topic here, this is a specifically created Community Wiki which gathers resources for Blender and it has been approved by the .  Just write in the appropriate answer/section. If you have concerns, questions, post a  question, so we don't clutter the comments, but you can link your meta question from the comments.  Questions regarding such resources are not allowed anymore, except for very specific and on topic requests (ask on  if you're unsure about your question). Follow the instructions made in the question about how to post, what can be posted, etc.  Learning             Assets    (also see: )   Reference Images/Blueprints (also see: )    Tools    (also see: )      Other   Special Interest ()     Also see the .


For example, if someone asks this question:     I'm getting an error doing X. Why?   A possible answer could be:     You need to do Y to avoid getting this error.    If Y is a technique or tool and if Y has a tag, should I edit the question to add the  tag? It seems correct because specialists in  will be able to find the question and add more useful information.  However, I can see two issues:   If  or  is also a possible solution, the question will have many distinct tags.   Example  Question:     My PC is freezing. What should I do?   Answer 1:     You need to run an anti-virus to remove malwares.   Answer 2:     Your PC may be overheated. Check if your fan is working correctly.   So, in this case, should I add  +  to the question?     If the question is marked with , the OP will look a bit dumb for asking something that is quite obvious if you see the tag.   Example  Question:     What series is it?   Answer:     This is "Game of Thrones".   Adding a  tag would make the OP to look dumb.  Another example for this would be:  Question:     How can I securely store an user password?   Answer:     You should hash the password before storing it.   In this case, should I add the  tag?     So, how should I proceed? Is there a generic guidance?

Here's a scenario:  Someone asked about "How to build a SQL query to get count and blah blah blah..."  His only tag is . I added the  and  tags to it.  Someone else answered with a nice SQL statement that has a "group by" statement which seems "logically inevitable".  I proceed to add a tag . I did that on the basis that someone who searches for  will be able to find this post useful, just as I did. My concern is, it wasn't described at all in the question, nor was it implied, unlike  and .  What is the community opinion?  The scenario above is a real one . And the one who answered it nicely is Jon Skeet.


This is a question about time dilation and different observers. Say you had two observers. One on earth and the other one traveling around 20% of the speed of light. The observer on earth will age faster than the observer traveling at 20% the speed of light.  The question is, will the observer traveling at 20% the speed of light travel into the person that's on earth's future? Say 30 years go by for the person on earth but only 5 years pass for the person traveling at 20% the speed of light.   Is the person traveling at 20% the speed of light just in another reference frame and the person on earth will still age and experience 30 years passing or will the person on earth and the one traveling at 20% of the speed of light both experience 5 years passing but the person traveling at 20% the speed of light will just end up in the person on earth's fututre?  If I understand this correctly, the person traveling at 20% the speed of light isn't traveling into the future of the person that's on earth, their just both in different reference frames relative to each other so the person on earth will have experienced 30 years and the person traveling at 20% of the speed of light will experience 5 years. Is this correct?  Also, does the rate entropy increases slow down as you move closer towards the speed of light?

Please will someone explain what time dilation really is and how it occurs? There are lots of questions and answers going into how to calculate time dilation, but none that give an intuitive feel for how it happens.


(1) Find the sum of the power series    $$\sum_{n=1}^{\infty} nx^n$$  (2) Find the sum of the series  $$\sum_{n=1}^{\infty} \frac{n}{3^n}$$  Any tips on solving the sum of series/power series?

I am struggling a bit with power series at the moment, and I don't quite understand what this question is asking me to do? Am I meant to form a power series from these, or simply evaluate that series? Any explanation/working is appreciated.  Using power series representation, calculate  $$\sum_{n=1}^\infty \frac{n2^n}{3^n}.$$


While using the command   sudo apt-get upgrade   I lost my internet. When I again used the command   sudo apt-get upgrade   I got the following error:  Unable to fetch some archives, maybe run apt-get update or try with --fix-missing   What to do? I am using 14.04 version.

I'm trying to install phpMyAdmin using sudo apt-get install phpmyadmin but encountering this error  Err http://gb.archive.ubuntu.com/ubuntu/ precise-updates/main mysql-common all 5.5.34-0ubuntu0.12.04.1   404  Not Found [IP: 194.169.254.10 80] Err http://security.ubuntu.com/ubuntu/ precise-security/main mysql-common all 5.5.34-0ubuntu0.12.04.1   404  Not Found [IP: 91.189.91.15 80] Err http://security.ubuntu.com/ubuntu/ precise-security/main libmysqlclient18 i386 5.5.34-0ubuntu0.12.04.1   404  Not Found [IP: 91.189.91.15 80] Err http://security.ubuntu.com/ubuntu/ precise-security/main mysql-client-core-5.5 i386 5.5.34-0ubuntu0.12.04.1   404  Not Found [IP: 91.189.91.15 80] Err http://security.ubuntu.com/ubuntu/ precise-security/main mysql-client-5.5 i386 5.5.34-0ubuntu0.12.04.1   404  Not Found [IP: 91.189.91.15 80] Err http://security.ubuntu.com/ubuntu/ precise-security/main mysql-client all 5.5.34-0ubuntu0.12.04.1   404  Not Found [IP: 91.189.91.15 80] Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/m/mysql-5.5/mysql-common_5.5.34-0ubuntu0.12.04.1_all.deb  404  Not Found [IP: 91.189.91.15 80] Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/m/mysql-5.5/libmysqlclient18_5.5.34-0ubuntu0.12.04.1_i386.deb  404  Not Found [IP: 91.189.91.15 80] Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/m/mysql-5.5/mysql-client-core-5.5_5.5.34-0ubuntu0.12.04.1_i386.deb  404  Not Found [IP: 91.189.91.15 80] Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/m/mysql-5.5/mysql-client-5.5_5.5.34-0ubuntu0.12.04.1_i386.deb  404  Not Found [IP: 91.189.91.15 80] Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/m/mysql-5.5/mysql-client_5.5.34-0ubuntu0.12.04.1_all.deb  404  Not Found [IP: 91.189.91.15 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?   What could be the issue here? How do I solve it?


I have an exception and I don't know how to solve it.  Person a = new Person(); Scanner in = new Scanner(System.in); System.out.println("Please type name: "); String name = in.nextLine();   It says there's an exception in the first line. The following code is the default constructor.  Person(){          this.name = "No_Name";          this.surname = "No_Surname";          this.number = "No_Number";          this.personalCode = "No_personalCode";          this.dateOfBirth.set(Calendar.DAY_OF_MONTH, 1);          this.dateOfBirth.set(Calendar.MONTH, Calendar.JANUARY);          this.dateOfBirth.set(Calendar.YEAR, 1900);      }   Class person full code:  import java.util.Calendar; public class Person {      String name;      String surname;      private String number;      private String personalCode;      private Calendar dateOfBirth;         Person(){          this.name = "No_Name";          this.surname = "No_Surname";          this.number = "No_Number";          this.personalCode = "No_personalCode";          this.dateOfBirth.set(Calendar.DAY_OF_MONTH, 1);          this.dateOfBirth.set(Calendar.MONTH, Calendar.JANUARY);          this.dateOfBirth.set(Calendar.YEAR, 1900);      }      Person(String name,String surname,String number,String personalCode,Calendar dateOfBirth){          this.name = name;          this.surname = surname;          this.number = number;          this.personalCode = personalCode;          this.dateOfBirth = (Calendar) dateOfBirth.clone();       }       Person setName(Person a, String name) {          a.name = name;          return a;      }      Person setSurname(Person a, String surname) {          a.surname = surname;          return a;      }      Person setNumber(Person a, String number) {          a.number = number;          return a;      }     Person setpersonalCode(Person a, String personalCode) {         a.personalCode = personalCode;         return a;     }      String getName(Person a) {         return a.name;     }     String getSurname(Person a) {         return a.surname;     }     String getNumber(Person a) {         return a.number;     }     String getPersonalCode(Person a) {         return a.personalCode;     }     Calendar getDateOfBirth(Person a) {         return a.dateOfBirth;     } }

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


I have built a new PC and had to buy Windows from retailer store.   During the installation I entered the 25 digit key.  Created only local account.  Now I was curious about the installation process and saw: Windows is activated with a digital license.  Why is it activated using a digital key? I did use the 25 digit key from inside the bought Windows box. Went something wrong?

If you activated a free upgrade to Windows 10 or bought and activated   Windows 10 from the Microsoft Store, you have a digital license for   your device. This means you can reinstall the same edition of Windows   10 that your device has a digital license for without entering a   product key. During reinstallation, if you’re asked to enter a product   key, you can skip this step. Windows 10 will automatically activate   online after the installation is complete.   source:   Does MS digital license 'fingerprint' hardware information  during the free upgrade / activation and store it (at Microsoft) , so that the next re-install queries MS for the fingerprint and activates Windows 10?  Thought the disk drive may change, I expect that none of the other fingerprinted hardware will change.


To give some background, I am attempting to solve the problem from Artin's algebra textbook which was already asked in this link:  Now, I would like to prove the following two claims which are not obvious to me. If I can prove these, I will be able to show that $\zeta_5\notin \mathbb{Q(\zeta_7)}$ as needed. I suspect that both claims will have similar proofs.  Claim 1: $\zeta_5$ has degree $4$ over $\mathbb{Q}$ Claim 2: $\zeta_7$ has degree $6$ over $\mathbb{Q}$  Attempt to prove Claim 1 Let $α=\zeta_5$. I would like to find the monic irreducible polynomial for $α$, but unfortunately I do not know what it is yet. I see $α=cos(\frac {2π}5)+isin(\frac {2π}5)$ and $α^4=cos(\frac {4π}5)+isin(\frac {4π}5)$. Please help me to find the irreducible polynomial, and (ideally) to show that it is irreducible.

Is it true that $[K(\zeta_n):K]=\phi(n)$ where $\zeta_n$ be primitive root of unity and K be field of char zero?  I think it should be equal to the degree of cyclotomic polynomial which has degree $\phi(n)$.  Can someone please elaborate that what is the procedure for finite fields


My understanding is bounties are used to attract more viewers for a possible difficult or an urgent question.  My question is: what if I already see somebody is answering my question and putting extra effort to provide very clean and working code, and I'm so happy with the answer?  In this case I really want to reward that person with more than just an up-vote.   Is it legitimate that I put a bounty on my question (which already has a solid answer) and then award it to that person?

It's possible to offer and award bounties of reputation on questions.   What is a bounty? How can I find questions that have a bounty attached? How do I start a bounty? When can I start a bounty? Why is the system requiring me to choose a bounty amount that's higher than the minimum? Can I use Markdown formatting in the bounty remarks? Can I edit the remark? How long is the bounty period? How do I award a bounty? Can I award a bounty to my own answer? Can I award a bounty to an old answer? If I offer a bounty on someone else's question, can I award the bounty to their answer? After awarding the bounty, can I remove it or move it to another answer at a later time? What happens if there's no answer after the bounty period? What happens if I feel my question is still unanswered? What is automatic awarding? Are bounty awards exempt from the 200 points/day reputation limit? How does Community Wiki mode affect bounties? How does user deletion or post dissociation affect bounties? Can I award a bounty to an answer from a deleted user or one where the author was dissociated? Can I offer a second bounty after the first one has expired? Can I raise my bounty? What happens if a bounty question is closed or deleted? Why can't I vote to close or migrate a bounty question? What happens if I delete my account while I have an active bounty? Do I keep an awarded bounty when I delete my answer? What happens if a question where I awarded a bounty later gets deleted or migrated? Can I cancel my bounty? Can I affect / divide / share part of my bounty to two (or more) users? How many outstanding bounties can a single user have?      See also:  in the Help Center


I am trying to copy a text to a clipboard using below command:  Clipboard.SetText(textToCopy);   but an exception is thrown:    Anyway, text is correctly copied to clipboard. I can catch the exception so the user does not see it but I would like to know what is happening.

Why does the following code sometimes causes an Exception with the contents "CLIPBRD_E_CANT_OPEN":  Clipboard.SetText(str);   This usually occurs the first time the Clipboard is used in the application and not after that.


I need to create an array of images. when I try to do the getGraphics method of the Graphics class to access the Image I created in the array index it throws the java.lang.NullPointerException error even though a few lines above I created the image in that index  I tried changing the index and changing the condition of the foor loop, but it still enters the loop only once and says that the array in index 0 is null.  private Image[] frames = new Image[100]; for (int index = 0; index < frames.length; index++){         if (frames[index] == null)          {             frames[index] = this.createImage(SCREEN_WIDTH, SCREEN_HEIGHT);         }          Graphics graphic = frames[index].getGraphics();   I expect the array to be full of images at the end, in order to paint them and finish the job.


Why do some use the equality symbol "$\;\stackrel{\text{def}}{=}\;$" for some definitions? For instance, $$\varepsilon \;\stackrel{\text{def}}{=}\; \frac{\Delta(L)}{L}$$

I'm used to people using the symbol $\equiv$ when defining quantities. I might see expressions like  $$\frac{df}{dx} \equiv \lim_{\delta\to 0} \frac{f(x+\delta) - f(x)}{\delta} = 2x \,.$$  where the first part is what is meant by the symbol $df/dx$, whilst the second is an equality that holds in the specific case being considered. On the other hand, what I understand the symbol $\equiv$ to actually mean is 'equivalent to'. A good example of such a usage would be  $$ \sin^2 \theta + \cos^2 \theta \equiv 1 \,. $$  The two usages to me seem rather different. The statement above is not a definition of $\sin$ and $\cos$, and certainly not a definition of $1$! Rather it is a statement with content. The first usage of $\equiv$ that I gave is, on the other hand, content-less, for it only serves to define a symbol.  So what I'm wondering is this:  Are the two meanings I've outlined above in fact not all that different? Or if they are, why is it common to use the same symbol for both? Do we need a new symbol for 'defined to be'? I believe I have seen before the symbol  $$ \stackrel{\mathrm{def}}{=} $$  but it is used very rarely. It is not possible that the different usages of the symbol could cause confusion among students? Or would most people agree that meaning is clear from context?  Thank you.


Why does this difference matter? The two blocks in the code below differ by the last line:  #!/bin/bash if [[ -n "$1" ]]; then     sleep 1 &     p=$!     kill $p &> /dev/null else     sleep 1 &     p=$!     kill $p &> /dev/null     /bin/true # This line is the sole difference. fi   Name it a.sh, and I get (on my Linux box)  $ ./a.sh /a.sh: line 16: 18103 Terminated              sleep 1 $ ./a.sh foo $ # no "Terminated" message   Why no message in the second case? Bash's basic behavior is to print "Terminated" ().  (NB I use p=$! in my true code, but in the above case you can use kill $!.)  EDIT:  kindly referred to the question "" in a comment. (It's rather a digression, but fun reading.) Unfortunately, the answer that comment belonged to was deleted, so I here record it. Thanks Sergiy.

Here is the behaviour I want to understand:  $ ps   PID TTY           TIME CMD   392 ttys000    0:00.20 -bash  4268 ttys000    0:00.00 xargs $ kill 4268 $ ps   PID TTY           TIME CMD   392 ttys000    0:00.20 -bash [1]+  Terminated: 15          xargs $ ps   PID TTY           TIME CMD   392 ttys000    0:00.21 -bash   Why does it show the [1]+  Terminated: 15          xargs after I kill a process, instead of just not showing it as it was just killed?  I'm using bash on Mac OS X 10.7.5.


Show that if $n$ is a positive integer, then $1+2+...+(n-1)\equiv 0 \mod n$  My attempt: If $n=1$, $0\equiv 0 \mod 1$ Assume that, $1+2+...+(k-1)\equiv 0 \mod k$ for some $k\in \Bbb{N}$. $1+2+...+(k-1)+k\equiv (0+k) \mod k $ $\equiv k \mod k$ $\equiv 0 \mod k$ But I want to show that $1+2+...+(k-1)+k\equiv 0 \mod (k+1) $, how can I Do it please?

For example, the sum of 1, 2, and 3 (three consecutives -- an odd number) is 6, which is a multiple of 3.


An interesting question popped into my head today regarding laser light. First, we know that all matter is made up of atoms, and that photons are considered to exhibit wave/particle duality. But if you shine a laser on a mirror, the light is reflected in a coherent way, i.e., the reflected laser beam remains concentrated and isn't spread out or noisy or diffuse. In other words, the angle of reflection equals the angle of incidence and it does not scatter.   The question is, why does it not scatter, given that a mirror is made up of atoms, photons should be hitting the atoms at different angles, and therefore scatter as they reflect from the mirror?

From the school physics I know that the material objects bounce from the plane surface at the same angle, losing some kinetic energy. In the same school I was taught that the light (and waves in general) obeys this principle too.  Obviously, in the case of light the plane surface should be a perfect mirror. But I can't understand how should this work from the quantum point of view. Let's assume that our mirror consists of a single silver atom.  Why should the electrons of this atom re-emit consumed photons at some specific angle?


If the correlogram of $Y_t$ displays slow decay (i.e., non-stationarity), is this indicative of a unit root? I reasoned that for the model $Y_t = Y_{t-1} + u_t$, the ACF is equal to 1 for all lags, and therefore, the answer to my question is yes. But I just want to be sure.

Can someone please tell me how the acf and pacf look like for a unit root process?


I have a chrome book. hp chromebook 14. I want to install ubuntu on it. No dual booting. just simple ubuntu. is there a way?

I have installed Ubuntu 13.04 on my desktop (runs like a charm). Then I used Crouton to install Ubuntu 12. 04 on my chromebook samsung (ARM). It also works quite well.  Here comes my question. Can we have a true Ubuntu (preferably 13.04) on my ARM chromebook?  It seems that the Crouton/Ubuntu is not 100% the real thing.  The best option would be to have the full Ubuntu 13.04 and remove the Chrome OS.


For which numbers $n$ exists a group of order $n$ with center {e} ?   And how many groups are there for a given order ?   The first such numbers are $6,10,12,14,18,20,21,...$ Groups of order $32,40,64$, for example have not center {e}. For $n=18$, we have $2$ groups with center {e}  Is there an easy criterion or formula ?


Is the auxiliary verb "had" needed in this sentence?  Amy from finance had emailed me an approval form to fill out.  I sent it back last week.  or  Amy from finance emailed me an approval form to fill out.  I sent it back last week.

I have never had this problem before. But after seeing some questions posted on ELU, I started to doubt. I have been through links1, pages of grammar books2, a lot of questions3 posted here and ELU. I now still can't seem to understand how the past perfect is exactly used. The references sometimes even contradict each other.  What I had understood so far was      The past perfect is not necessary if we are not 'going back' to the earlier past, and simply moving from one event to another.   but I then saw a lot of other 'rules' including      If the sequence is clear, the past perfect is not needed.   which is slightly different, less 'narrow' and can be applied in more situations than the first ruleA, and      The past perfect is optional only when talking about an action at a specific time.   This is confusing. Can anyone here clarify things out please?    A For example, for  Doing the survey [completed] -> Showing the result      We showed the result of the survey we did.      If the second rule is applied, the sentence above is fine (the sequence is clear), but not if the first rule since we are not moving from any event to the next and possibly even going back.    1  and   2 Practical English Usage (2005) by Michael Swan, Collins Cobuild Student's Grammar (1991). Upper-Intermediate Cutting Edge.  3 including , , ,  etc.


After install Nvidia drive 304.125 on ubuntu 15.04 display black screen i tried nomodeset but still the problem

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I have no idea what I'm doing but recently received some files that were sent in a STL format that I need to open. I was told to use Blender to see these files but I'm not sure how to import them.

I need to open .stl files with blender, without importing them!  In the properties of my .stl file, blender is set as "open with", but when I double click on the file it just opens blender as my preset user preference (without any objects). The same happens when I drag the file over the blender icon to open it that way.  Whats funny is that if I drag and drop the file over an older version of blender (2.49) then it opens the .stl file fine.  Any ideas?  Thanks


Let $(\mathbb{R},+)$ be the additive group of the reals and $(\mathbb{C},+)$ be the additive group of the complex numbers. Prove that those groups are isomorphic.   I think I got a solution using the fact that the real numbers have a Hamel Basis $B$, then proving that $B\times {0}\cup 0\times B$ is a Hamel basis for the complex numbers and noting that these sets have the same cardinality. However this result relies on Zorn's lemma and is thus not very elementary. Is there a simpler way to get it?

I think the answer is yes.   Sketch of the proof Consider $\mathbb{R}$ as a vector space over $\mathbb{Q}$. Let $\{e_\lambda:\lambda\in\Lambda\}\subset\mathbb{R}$ be its Hamel basis. Then $\{(e_{\lambda_1},e_{\lambda_2}):\lambda_1,\lambda_2\in\Lambda\}\subset\mathbb{R}^2$ is a Hamel basis of $\mathbb{R}^2$. Consider set theoretic bijection $i:\Lambda\to\Lambda\times\Lambda$ define map $\varphi:\mathbb{R}\to\mathbb{R}^2$ by its action on element of Hamel basis of $\mathbb{R}$ by equality $\varphi(e_\lambda)=(e_{i(\lambda)_1},e_{i(\lambda)_2})$. This is an isomorphism between $\mathbb{Q}$-vector spaces $\mathbb{R}$ and $\mathbb{R}^2$.  Question Could you tell me is this proof correct, and if it is not, where is the mistake?  EDIT: Thanks to GAJO we found that this proof is wrong. The correct one basis is  $$ \{(e_\lambda,0):\lambda\in \Lambda\}\cup\{(0,e_\lambda):\lambda\in\Lambda\} $$ So we had to look at bijections of the form $i:\Lambda\to\Lambda\coprod\Lambda$ and the desired linear operator is defined by equalities $\varphi(e_\lambda)=(e_{i(\lambda)},0)$ if $i(\lambda)$ lies in the first copy $\Lambda$ and $\varphi(e_\lambda)=(0,e_{i(\lambda)})$ otherwise.


I'm trying to find a short sci-fi story that I read some 40 years ago (in the early to mid 70's).  Earth had been isolated with some force field as Humans were regarded as too dangerous/uncivilized by the galactic civilization, but something had happened and Humans were potentially needed to help..  The story was about earth being checked out to see if Humans were now safe enough or it would be even more risk to let them loose.  The story ends with the force field being released and Earths moon being taken along by the Humans so that they would have something to remind them of home...  That's what I vaguely recall.  Any pointers would be most appreciated.

Unique short SF story where aliens being invaded by other aliens, went looking for allies (to help save their galactic empire).  While being chased by the antagonistic aliens, they encountered a barrier surrounding a solar system. They somehow managed to disable it and found a solar system where the third planet from the Sun showed signs of life. When they landed, they were received by a human girl who greeted them. The enemy ship which followed them also landed, but were destroyed by the humans easily.  Upon learning of the aliens request, the humans decided to help the aliens, and moved their entire world to follow the aliens' ship. Too late the aliens realized that these humans were the ancient war mongering race which was sealed up eons ago and they had accidentally released them.  Could someone please help to identify this title for me. Thanks.


Based on a cell value = true or false, I conditionally formatted rows to turn black.  That means that I need to scroll down to find the set of rows that did not turn black.  I would prefer that all my rows with data remain unexpanded and remain hidden and only expand when cell value = true.  Is there a way to unhide the few, select rows when the cell value = true and compress/hide if cell value=false - without using macros; or any macro code suggestion if one is needed.  This will forego the scrolling.

I am trying to write a VBA code that automatically hides rows if a value in the row is equal to "". My range of values is A37:A400. Because my range is so big my previous VbA is to slow and looks one line at a time. Any ideas to make a fast code that will go though this large list and hide rows in a quick fashion. Right now it takes about a minute to hide the rows which is too Long.   Sub HideRows()     Dim cell As Range     For Each cell In Range("A37:A400")         If Not IsEmpty(cell) Then             If cell.Value = "" Then                 cell.EntireRow.Hidden = True             End If         End If     Next End Sub


Suppose that $\{a_n\}$ is  a sequence such that $\displaystyle\lim_{n \rightarrow\infty} {n^x}a_n=a $ for some real $\,x$. Calculate $$\lim_{n \rightarrow \infty}n^x (a_1\,a_2\dots\,a_n)^{\frac{1}{n}}$$  My attempts : I take  $a_1=a_2 = \dots =a_n = a$ after that $\lim_{n \rightarrow \infty}$ $n^x (a_1\,a_2 \dots \,a_n)^{\frac{1}{n}}=  \infty \, a = \infty$ Is it correct ?? or not Please help me. Any hints/soluion.....

If $\lim_{n\to\infty} x_n = \alpha$ and $x_n \gt 0$ for all $n$, show that $$\lim_{n \to \infty}(x_1x_2\dots x_n)^{1/n} = \alpha.$$


I have a simple problem, but the solution is rather difficult to find.  I would like to use the same TTY font in Ubuntu in my GUI environment.  I don't know the name of this font, and I don't know how to set it to my GUI.  I hope you can help me with this.  Thanks in advance.

Is there a way to set a specific TTF font to be used on the console? (I believe you might have to convert it to a bitmap font?)  If it needs to be converted, what tools can I use to do the conversion? Otherwise, how do I pick Ubuntu Monospace for my console font?  (I already have the Ubuntu Monospace font installed from the beta PPA for it.)  Edit: I already set gnome-terminal to use Ubuntu Mono. Now I'm wanting to set the all-text screens I get when I press Ctrl+Alt+F1 to use the same font.


My camera will not let me zoom in anymore after I zoom in on a huge obj. I know it is probably designed that way so we can zoom in anymore after certain amount,but I want to know if I can break that. I really need to zoom in more.

I often find that I can zoom in to a point, but then cannot zoom any more, even when there is a lot of room to zoom to the meshes on the scene.   This is particularly annoying in the following scenario:  I often land up left clicking on the scene and the 3D cursor shifts there. I use Shift+C to shift the 3D cursor back to the origin. However, this also centers the view on the cursor and shifts the view to show all objects, and sometimes this zooms things way out – at this point, if I try to zoom in, I can zoom in to a point (using the pinch/zoom on trackpad), but then it stops zooming in.   How do I zoom in after that? Is there anything else I am doing wrong in this case?


I don't think this is how questions are supposed to look in the Android app...    Android 4.2.2, app version 1.0.68 (which I believe is the most current)

I can reproduce that every time now, I go to a site, open an article, then to the next site, open another article. The Feed page pops up for a second, the article page lays over this with some some transparent areas (see picture). The same app-version is ok on a Smartphone with Android 4.4.2. I also sent in some bug reports.    Edit  1.0.71 isn't the solution yet. I go to Meta SE, then to an article. When I want back to Meta SE again, it crashes. Much earlier than before. I already sent in a bug report for this.  Another Edit  I can describe it better now. From the questions-page of a site I go to a post. When I use the back button, everything is ok, I can go to the next site. When I try to go to the next site directly from the post, it crashes. This only happens on the Nexus 10 with Android 5.1.1, App version 1.0.71. Hope this helps.  Edit3  This is fixed in 1.0.73 now. Thanks again.


I have read in  if it is true that $2^{282589933}-1$ is a new Mersenne prime which was discovered in 07 december 2018 , Really  I want to know how this was tested to be a prime number ?

As of December 2017, the largest known prime number was the Mersenne prime $2^{77232917} – 1$.  For such a large Mersenne prime, what are the techniques available for one to verify that it is in fact a prime?  Is it simply a matter of brute force checking, or are there other more elegant techniques available?


Let $p:\mathbb{R}\rightarrow\mathbb{R}$ be a polynomial of odd degree. Prove that there is a solution of the equation $$p(x)=0, x\in\mathbb{R}$$  I am giving this question in an analysis textbook and the only machinery I have to work with is the sequential definition of continuity and the intermediate value theorem. Using only these ideas I am having difficulty coming up with a concrete proof.

I want to prove that every real polynomial of odd degree has at least one real root, using  the intermediate value theorem.  Let $P(x) = x^{2n+1} + a_n x^{2n} + . . . + a_0$ for each $a_i \in \mathbb{R}$ and $n \in \mathbb{N}$.  By the fundamental theorem of algebra I know that $P(x)$ has exactly $2n+1$ complex roots, so  $P(x) = (x+r_1)(x+r_2) . . . (x+r_{2n+1})$ for each $r_i \in \mathbb{C}$  I do not know how to complete this but I do know that, at some point, I probably have to show that each root with imaginary part non zero has to come in conjugate pairs, and since $2n+1$ is odd there is at least $1$ root that is imaginary part $0$ and thus real.


This works: (main):  glfwSetCharCallback(window, Console_Input);   (global):  void Console_Input(GLFWwindow* window, unsigned int letter_i){ }   If I try to put it inside class: (main):  Input_text Text_Input(&Text_Input_bar, &GLOBALS); glfwSetCharCallback(window, Text_Input.Console_Input);   (global):  class Input_text{ ... void Console_Input(GLFWwindow* window, unsigned int letter_i){  } void Update(){     if(active == 1){         MBar->Re_set_bar_width(str);         MBar->update_bar();     } } };   It doesnt work. I get error: cannot convert 'Input_text::Console_Input' from type 'void (Input_text::)(GLFWwindow*, unsigned int)' to type 'GLFWcharfun {aka void ()(GLFWwindow, unsigned int)}'  I dont want to write functionality inside callback function. I need self-managing class. Is there a way to set glfwSetCharCallback to the function inside a class?

I'm using an API that requires me to pass a function pointer as a callback. I'm trying to use this API from my class but I'm getting compilation errors.   Here is what I did from my constructor:  m_cRedundencyManager->Init(this->RedundencyManagerCallBack);   This doesn't compile - I get the following error:      Error  8 error C3867: 'CLoggersInfra::RedundencyManagerCallBack': function call missing argument list; use '&CLoggersInfra::RedundencyManagerCallBack' to create a pointer to member   I tried the suggestion to use &CLoggersInfra::RedundencyManagerCallBack - didn't work for me.   Any suggestions/explanation for this??  I'm using VS2008.  Thanks!!


Why this line doesn't work:  $db_Table = "myTable";  $pdo->prepare("INSERT INTO :db_Table VALUES (...  $query->execute(array(     ':db_Table' => $db_Table,     Whereas this one works:  $pdo->prepare("INSERT INTO myTable VALUES (...   How can I solve it ?

Why can't I pass the table name to a prepared PDO statement?  $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) {     var_dump($stmt->fetchAll()); }   Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do  $sql = "SELECT * FROM $table WHERE 1"


Consider a surface diffeomorphic to a cylinder (the boundary is 2 curves diffeomorphic to circles). Suppose the boundary curves are geodesic, can the surface have non-vanishing gaussian curvature (i.e. $K \neq 0$ everywhere)?  I tried to use the Gauss-Bonnet theorem, but I'm not sure how.

The question is as follows.  Imagine we have two closed geodesics on a surface, where these two geodesics bound a cylinder together and the geodesics are diffeomorphic to circles.  Can the cylinder have $K>0$ everywhere or $K<0$ everywhere?  Here $K$ is Gaussian Curvature.   What's confusing me about this question is that a cylinder has Gaussian Curvature of $K=0$ everywhere, so wouldn't the answer to both questions be no?  But then I don't get the point of the question with the geodesics.  Thank you in advance


I have several virtualhosts, and I need to run different PHP versions. I have php-fpm and FastCgi installed, but how can I configure it? I'm using Ubuntu 16.04

I am trying to update to install PHP 5.5, 5.6 or 7.0 in Ubuntu 12.04/14.04/16.04 LTS, and I can only get PHP 5.3.10 for Ubuntu 12.04, PHP 5.5.9 for Ubuntu 14.04 or PHP 7.0.4 for Ubuntu 16.04 using official repositories (using apt-get).  I'm not really sure how to do a manual update – as I need:   to play around with the new(est) PHP features to install older PHP version due support in the software


I started to dig into the whole Linux pty and tty hell. I'm trying to understand how it works here in Linux so I was reading quite a lot of articles that covered this topic.   So far I know:      TTYs are TERMINALS which are the last "secretary" to talk to kernel.    PTS are virtual terminals, that on the one end are connected to the TTY and on the other end are connected to the terminal-emulator (the one that we can for example open by clicking applications->system tools->terminal. or to ssh session(?). So ssh uses another pts.    That seems pretty clear to me because when I will do w in a shell on my system I get:  21:26:53 up 2 days, 11:35,  2 users,  load average: 0.11, 0.08, 0.08 USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT kris     tty1     :0               Thu09    2days 52:28   0.05s pam: gdm-passwo kris     pts/0    :0.0             21:18    0.00s  0.02s  0.01s w   The tty1 is a terminal session, which was started when I logged into my machine, and the pts/0 is a virtual terminal (instance of App -> System Tools -> Terminal).  However, what is the pty then? If I will connect to my server through ssh then another pts will be spawned, but when will another tty be spawned, and whats the point of pty, from the man pty it seems to me like it is this:   Emulated terminal (gui terminal) talks to pts This pts in turn talks to pty , which talks to tty   That doesn't make sense.  Please try to explain it using examples because it is very easy to fall off with all the differences between consoles, terminals, virtual terminals, emulated terminals, pts, pty, tty.

I think these terms almost refer to the same thing, when used loosely:   terminal shell tty console   What exactly does each of these terms refer to?


I was teaching past simple and there is this exercise in which we have to conjugate verbs to the past form. I know that we add an auxiliary to make a question, but do we sometimes omit this auxiliary for one reason or another.  The question that made me wonder is with (who).     Who did close the door?   or     Who closed the door?

Often when I am on a flight, nearly every sentence I hear from the flight attendants contains an unnecessary emphatic auxiliary in its main clause; that is, an altogether unnecessary do or unnecessary emphasis on other auxiliaries:     We do apologise for the delay, which was due to technical issues, but we will be taking off shortly, and we do hope you enjoy the flight. We do ask you to fasten you seatbelt now, and if you do have any questions, we do hope you won't hesitate to ask us.   What is the purpose of this constant emphasis? My guess is it's supposed to somehow elevate their language to a higher register, but why do flight attendants in particular seem so fond of this?


A common expression for hydrodynamic drag is a a force that goes $\propto -k v^2$.   Physically I have alwasys interpreted this as being related to the ram pressure $\propto \rho v^2$, i.e. for an object to move through a fluid at speed $v$, one needs to impart momentum $\propto v$ and kinetic energy $\propto v^2$ to air molecules for them to move out of the way.  Once the object reaches the speed of sound, however, it will be moving through the fluid faster the molecules get out of the way, hence causing a shock wave - the familar sonic boom.  How will air resistance change, if it will, in the supersonic regime?

I know that if an object moves in the air, it can experience two types of drag, laminar and turbulent. For instance, I have a meteor of ideal spherical shape falling from edge of space, say, 100 km up at the Earth surface with initial velocity of 1 km per second. I would consider turbulent drag, but is it still applicable at supersonic velocities? How do I estimate meteors velocity when it hits the ground?


Installation does not show install Ubuntu alongside Windows.  I have created Unallocated space of 50 GB from disk management in Window for booting Ubuntu.  But at the time of installation it isn't showing that partition.

Whenever I startup from the LinuxLive USB, and try to install Ubuntu 12.04, it only gives me two options instead of the usual 3 or 4. My options are "Replace Windows 7 with Ubuntu" and "Something Else". Whenever I go into "Something else", it looks extremely confusing. How do I install it side-by-side while using the "Something else" section? These are my partitions.   /dev/sda /dev/sda1 ntfs (104Mb, System Required Partition) /dev/sda2 ntfs (1000097Mb, Windows 7 Partition)   Or should I try reinstalling my installer on a CD rather than USB and maybe then it will have the "Install alongside" function?


Two coins are flipped, if at least one them lands heads up, what is the probability that both do?  I've tried solving this problem countless different ways but I can never get it right. I know that "at least one" means "one or all" so I use P(AorB) then the result I divide it over the total number of ways the event can occur.

I have a doubt because I think that once the result of the first coin is obtained, just simply await the outcome of the second, which is completely independent of the previous one, and then we have a chance of $\frac12$ to get a head again.  But someone else tells me that as the possible events are:   Head - Head Head - Tail Tail - Head Tail - Tail   then when we get a head we restrict ourselves to the first three cases, so the probability would be $\frac13$.  What is the right way?    I know there's a difference between saying "first came head" to say "one of the two came head", but if we have the first fact, aren't we supposed to know which one is that came head?


Yesterday my windows 10 installed these unexpected games automatically:         12 Labours of Hercules III Girl P..., All Casual Games, All Enthusiast   Games, All Family Games, All Kids Games, Azkend 2 The World Beneath,   Building the Great Wall of China..., Command and Conquer Tiberiu...,   Coyote The Outlander, Delicious Emily's Wonder Wedd..., Entwined The   Perfect Murder, Family Vacation 2 Road Trip, Home Makeover, IGT Slots   Paradise Garden, Imperial Island Birth of an Empire, Insane Cold Back   to the Ide Age, Jewel Match Snowscapes, Living Legends Frozen Beauty   C..., Lost Lands Dark Overlord Collec..., Malor Memoirs Collector's   Edit..., Mystery Expedition Prisoners of..., Plagiarii, Polar Bowler   1st Frame   .  As far as I remember I only had Solitaire.  I use Windows Defender. I'm on the latest Windows 10.  After searching online, I followed one of advices just now: I turned off Updates from more than one place in my Settings. I don't know if this could solve my problem.   Help?  UPDATE  Guys, that link solved my problem. After observing for about a month, my Win 10 didn't install any unexpected new games or anything secretively. Thank you.

I've upgraded my PC from Windows 7 Ultimate to Windows 10 Pro; overall it seems to be working fine, with small bugs here and there. One thing that I find really annoying is that Windows seems to think it is OK to install drivers and vendor-specific control panels for me.  I've always installed drivers manually to get around having all the bloatware (i.e., Realtek's audio management panels and other vendor-specific tweaking tools).  How do I stop Windows from automatically installing bloat on my custom PC, so that I can use the drivers I've exported from packages and binaries to get around bloats?  If I uninstall everything Windows automatically installed, it seems as if a reboot persists them and installs again.  Preferably I'd like to perform a clean install and have Windows skip installing any drivers automatically. Is this possible?


Typically, my kernel_task process uses 1-4% CPU and 100-700MB of memory. However, sometimes when I have the power adapter plugged in, the CPU usage jumps to around 500% (8 cores) and stays there until I unplug the power adapter. I can plug it back in and everything is fine for a few seconds or a few days, then it eventually happens again. How can I stop this from happening?

Occasionally my machine will have a kernel_task instance max out the CPU:    This can last from minutes to sometimes hours. The machine is effectively unusable in this state. Restarting doesn't help; a new kernel_task pops up again until it finishes whatever it's doing.  How can I find out what this process is doing?


I want to be member of the ubuntu community.What can I do,please help me

I have used Ubuntu for a while and want to find a way to give back to the community and help Ubuntu get better; is there a team in the Ubuntu community that is dedicated to helping users transition from user to contributer?


I'm trying to compile a LaTeX file with Kile on a laptop running Linux CentOS 7.  In the .tex file, I've the command \usepackage{dsfont} Kile does not compile my file and produces the following error:  File 'dsfont.sty'  not found  What can I do to solve this problem?  I tried to install all the texlive packages with this command, but it did not solve the problem:  sudo yum -y install texlive texlive-*.noarch  Edit: Ralf Stubner pointed out that there's  explaining what to do. I checked it but unfortunately it does not solve my problem and it does not provide solutions for Linux CentOS.

Hi I tried to install the package by  tlmgr install dsfont   but I only get  tlmgr: package repository http://ftp.gwdg.de/pub/ctan/systems/texlive/tlnet package dsfont not present in package repository.   I also installed the package doublestroke since I read somewhere that this package contains dsfont, but if I include dsfont I still get an error message..  Does anyone know how to help me?


I came across a fake/scraped version of Stack Overflow when Googling.   At first I thought it was just rogue Javascript popup ads that you guys might want to hear about but then my colleague pointed out that the site wasn't actually legitimate.  I've reported the site to Google is there anything else I should do?  It looks like it's scraping the real site as some of the results in the background are releveant to my original query, or is that just a coincidence?  EDIT:  After further navigating the site it looks like the real site with adverts on the top of it.

of Stack Overflow, all content posted on Stack Exchange sites by their users (i.e. you wonderful people) has been provided to the whole universe under . For my fellow non-lawyers, that license basically means:   Anyone can use any Stack Exchange posts at any time without having to ask for permission Making money off of the copied content is permitted You don't even have to copy stuff from here verbatim; you can just use it as a starting point and make whatever edits you want There are just two rules you have to follow:   You have to provide . Simple links to the original post and author info are just fine. You have to  and allow other people to use your content, as long as they follow these very same rules. How meta!    (If you ever forget any of that, and want to refresh your memory, the license info is linked to in the footer of every page.)  There are, in fact, a lot of people who republish varying amounts of our content for assorted reasons. Unfortunately, there are some Stack Content Republishers Attributing Poorly and/or Excelling at Ranking (SCRAPERs, for short).  In this context, "attributing poorly" means any use that doesn't follow our attribution rules or make any other reasonable attempt at give credit. This can get pretty egregious; I've seen SCRAPERs that not only don't link back to SE originals, but also use fake author info and post dates to make it harder to find originals. By "excelling at ranking," I'm referring to copycat sites that end up higher in Google results than the original SE sites do for the same content. That's not necessarily wrong, but in some cases, it indicates inappropriate SEO hackery.  So, the question is: what can you do if you spot a SCRAPER?


This is what I get each time I try to upgrade:   "The following packages have unmet dependencies:  libgl1-mesa-glx-lts-trusty: Depends: libglapi-mesa-lts-trusty (= 10.1.3-0ubuntu0.1~precise1) but 10.1.3-0ubuntu0.1~precise1 is to be installed                             Depends: libx11-6 (>= 2:1.4.99.1) but 2:1.4.99.1-0ubuntu2.2 is to be installed                             Depends: libxdamage1 (>= 1:1.1) but 1:1.1.3-2build1 is to be installed xserver-xorg-lts-trusty: Depends: xserver-xorg-core-lts-trusty (>= 2:1.11) but 2:1.15.1-0ubuntu2~precise1 is to be installed"   How can I workaround this problem?

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


I'm about to install Ubuntu 13.04 on my computer and I'm wondering how big each partition should be. I read that the swap area should be twice the size of your install RAM and I figured /home should take the space you have left, but how big should / be?    Further to this, I have two 500GB hard drives and want both of them to be available when I use the computer. Should I put / and swap on one drive while letting /home be on the other or should I put all partitions on one drive? If putting all partitions on one drive is the best option, what file-system should the other drive use?  Oh and just to clarify: I don't want to dual boot — just want the whole system to run Ubuntu.

What partitioning scheme do you recommend for a desktop? I've always created three or four primary partitions -- root, swap, home, and sometimes a separate boot partition. Ubuntu's default install offers LVMs. I've never had to add additional drives or space, so it never seemed like a big deal. Whenever I do a fresh install, though, I always think there might be a better way.


At around 2pm yesterday, I bought wraps from a street stand I'm familiar with. I brought it home... and forgot it existed. It's 10am next day, but it's untouched and as well sealed as a takeout plastic bag can be.  Normally I wouldn't chance it, but I remember a friend saying the microwave can... sterilize the food? I forgot what word he used. Should I try blasting it in there or just throw them out? I'm poor but not starving, so it's more about "I paid for that, so I want to eat it if it's salvageable"

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?


It'd be nice to somehow distinguish comments that were expanded from those that were shown by default.  Sometimes I'll read the first few comments which have been voted up and then hit expand to show remaining comments (some of which might also be voted up, just less I guess). Once expanded, it's not obvious which ones I've already read and I pretty much have to rescan the entire list.  This is similar to the old MS Office menus which would initially show recently used options but after a delay would show all options.   Some unobtrusive highlighting or bordering or something--maybe just a dash in the number of votes position or something tiny and subtle...

When there are several comments some of them get hidden, which I don't mind, except when comments in the middle are hidden and I don't realize it till I get to the end. Then I have to unhide the comments and try to figure out which ones I haven't read.  The comments stay in order as they should so you can follow them but when you hide random ones in the middle you can loose the context of the comments until you unhide them all.  I have a couple of ideas that could help with this.  Put the Show X more comments at the top of the comments instead of the bottom  Put some indicator that there or hidden comments between these two  Comment this is the first comment Comment this is the second comment ... Comment this is the fourth comment, comment three is hidden indicated by the dots Comment this is the fifth comment ... Comment this is comment number nine, comment 6, 7, and 8 are hidden    Where the dots equals some indicator that there are hidden comment between two comments  Finally you could highlight the newly shown comments when you hit the unhide comments link like you do when you post your question.  Update  Just wondering if this could get a second look? Seems the community really likes the idea, and Jeff is ultimately who made the decision not to do it.


Hi I am trying to get most recent transaction based on updated timestamp along with another column like i i tried with below queries but did not work. Create Table Transactions(Transaction_Id number,User_ID varchar(20),Transaction_Name varchar(20),Upd_Dt Date);  Insert into Transactions(Transaction_Id,User_ID,Transaction_Name,Upd_Dt)values(123,'User1','FROM_CUSTOME_ON_0107',to_date('11/26/2013','mm/dd/yyyy')); Insert into Transactions(Transaction_Id,User_ID,Transaction_Name,Upd_Dt)values(124,'User1','FROM_CUSTOME_ON_0207',to_date('12/26/2013','mm/dd/yyyy')); Insert into Transactions(Transaction_Id,User_ID,Transaction_Name,Upd_Dt)values(125,'User1','FROM_CUSTOME_ON_0207',to_date('01/26/2013','mm/dd/yyyy'));  Insert into Transactions(Transaction_Id,User_ID,Transaction_Name,Upd_Dt)values(126,'User1','FROM_CUSTOME_ON',to_date('02/26/2013','mm/dd/yyyy')); Insert into Transactions(Transaction_Id,User_ID,Transaction_Name,Upd_Dt)values(127,'User1','FROM_CUSTOME_ON',to_date('03/26/2013','mm/dd/yyyy')); Insert into Transactions(Transaction_Id,User_ID,Transaction_Name,Upd_Dt)values(128,'User1','FROM_CUSTOME_ON',to_date('04/26/2013','mm/dd/yyyy'));  Tried Query: Select tl1.Transaction_Id from Transactions tl1  where tl1.Upd_Dt = (Select max(tl2.Upd_Dt) from Transactions tl2) and tl1.Transaction_Name  like 'FROM_CUSTOME_ON_%';  How to get exact record which LIKE 'FROM_CUSTOME_ON_MMYY'?

Is there a way to make an Oracle query behave like it contains a MySQL limit clause? In MySQL, I can do this: select *  from sometable order by name limit 20,10  to get the 21st to the 30th rows (skip the first 20, give the next 10). The rows are selected after the order by, so it really starts on the 20th name alphabetically. In Oracle, the only thing people mention is the rownum pseudo-column, but it is evaluated before order by, which means this: select *  from sometable where rownum <= 10 order by name  will return a random set of ten rows ordered by name, which is not usually what I want. It also doesn't allow for specifying an offset.


My client wants country-based domains for their customers. For example, all customers from UK will be taken to the .co.uk site, even if they visit the .com site. And same for other countries.   I have used IP redirection for this. Redirection is OK.   Since all non-UK IPs are redirected to .com site, how will Google index the .co.uk site?  If I submit a sitemap of .co.uk and .com sites to Google and have country-based IP redirection in place, will Google (or any other bot) be able to visit?  My understanding is, Google bots have IPs from USA.  And, .co.uk and .com sites have 80 % content same. Will it impact on duplicate content?

Let's say I have a site that has multiple versions for different countries, e.g.:  www.example.com/us www.example.com/uk www.example.com/ca   and I want to use IP geolocation to redirect users who go to www.example.com to the appropriate country version of the site.  What is the best way to do that without confusing crawlers such as Googlebot or running into other SEO type trouble?


Comments from OP have a different font size than comments from others.   Example from :    Tested on Google Chrome on Samsung Galaxy S9 with Android 9 and with the "Desktop site" option activated in Google Chrome.

An issue similar to that described in  and likely to be related.  The comments for a question may vary in size:         Chrome for Android on Nexus 7 running 4.2.2 Jelly Bean. This also occurs on Firefox for Android:


I would like to create a simple script (probably Python 3) to generate invoices based on *.tex template. Is there any way to change some data in this template from the command line? I mean, for example, such a simple situation that I want to run the script and give the amount for the invoice that would be inserted into it: "python generate_invoice.py --value 300$" and that 300$ will appear in a specific field in the resulting pdf file. I couldn't find anywhere else to do that.

I compile most of my documents via Makefiles which take care of the bibliography, indexes, etc. Often I'd like to compile different versions from the same TeX file changing only small things (e.g. a beamer presentation plus a version with the handout option).  Is there any standard mechanism for passing parameters to the TeX file so that I can just type make handout to get the handout version in the above example?


Is there a way to save the currently opened tabs (URLs) of Firefox into a text file?

If I have a Firefox window open that contains 10 tabs, is there a way in Firefox or by a plug-in to get the URLs of those 10 tabs as a text file or some other format?  Right now if I want to do this I need to copy the URL of tab A, paste it somewhere, move to tab B, and repeat.  I could also bookmark all the tabs into a folder and export that, but that seems like such a hassle.  If there is no such method, could someone point me to some documents that describe the basics of writing a Firefox plug-in.  I am willing to write this myself if there is no "standard" way.


I'm a little confused about the 90/180 day visa program. I'm from Argentina and my son is Dutch. I stayed in the Netherlands for 79 days and wish to come back for his birthday. That is in 93 days.   Since I left the Schengen area for over 90 days, does that mean that I reset my visa and I can reenter again for 90 days or do I have to wait for the 180 days to pass to renter for 90 days?

I have searched the web a lot and could not find an answer that fits my situation. Here are two links that are quite contradictory:       My situation:  I've visited Portugal in December 2012 for 29 days on a Schengen visa valid from December 1st, 2012 to February 1st, 2013 for research purposes (I am a Ph.D. student). I want to visit Sweden from February 10th, 2013 to May 10th, 2013 (89 days). I have applied for a Schengen visa again (for research). How will the 90/180 rule work in my situation?


I've noticed since the December update to the iOS app that the inbox and achievement buttons in the toolbar are a bit... iffy.    they seem to move around a tiny bit based on whether achievements is showing a rep gain or its default icon when achievements shows a rep gain, it's much harder to tap   It's as if the frame of the achievements button is changing to the min size fitting it's content instead of staying at 44x44 (or whatever bar buttons are supposed to be these days).  Seen in iOS 10.2 on iPhone 7 Plus.

The navbar button for the rep/activity log can't be tapped when displaying a rating change (+5).     Persists between app runs.    App Version: 1.6.2.5 Device: iPhone 5 (Global) OS Version: Version 10.2 (Build 14C92)


I am not able to comment, when I am clicking on add a comment its jumping to the top of the page. Its happening everywhere on stack over flow (not on a single question)  what I have tried as yet   I have cleared cookies and cache Uninstall re-install Chrome Tried different web browsers   Here is the Console Log     …C%5C%22reputations%5C%22%3A%5B1%5D%7D%22&screenheight=800&screenwidth=1280   Failed to load resource: the server responded with a status of 501   (Not Implemented)   …3A%5B1%5D%7D%22&screenheight=800&screenwidth=1280full.en.js?v=f5db443c1ac0   Failed to load resource: the server responded with a status of 501   (Not Implemented)    Failed to load resource: net::ERR_BLOCKED_BY_CLIENT    Failed to load   resource: net::ERR_BLOCKED_BY_CLIENT   …ImJmIjp0cnVlLCJwbiI6ImFkemVyazYwOTkzMjY0MSJ9&s=u6WGz8x-1HNheTBJ8lGTLq7w_Eo   Failed to load resource: net::ERR_BLOCKED_BY_CLIENT

Most of the links on stackoverflow are not working. I suspect it is due to a js that is not being loaded.   I am getting following error in console. Can anyone please suggest on how to get rid of this error?    The problem occurs only for stackoverflow dropdowns/links. No issues in other communities.  The problem occurs in chrome and FF. Please note, I logged into stackoverflow using FF for first time.


How do I stop and start setInterval?  Suppose I have a textarea.  I want to stop setInterval on focus and restart setInterval on blur (with jQuery).

I am using setInterval(fname, 10000); to call a function every 10 seconds in JavaScript. Is it possible to stop calling it on some event?   I want the user to be able to stop the repeated refresh of data.


In the beginning there was Stack Overflow. Then Jeff Atwood created reputation. And he looked and saw it was good.   But there was one problem. In order to get reputation, you need upvotes, and nobody had enough reputation to upvote. Can you show me where the very first reputation points came from?

Is the birth of Stack Exchange documented somewhere? How did the system trust users in the very beginning before there were any users with any reputation?


I'd like to propose a home tab to sit long with questions, tags, users, badges and unanswered. It should list for the specific user you are logged in as all the questions with favourite tags. That way if you are following several tags, you can see all the questions tagged accordingly and answer them instead of clicking through each one to see any answered/unanswered questions.

Why don't we have a Tab that shows only questions for our favorite tags, showing recent first?  I keep having to scroll down the page to find the questions I'm interested in.  It'd be like the Unanswered Questions -> My Tags tab, but for all questions with my favorite tags.


In geometry there is a term called a pivot point. There exists a pivot point 'P' in the interior of a convex polyhedron in a euclidean space if and only if every single line through 'P' contains exactly zero or two vertices of the polyhedron.  I asked one of my professors, but he gave me a very narrow example of a cube, but I want to know the maximum number of pivot points that exist in a polyhedron. Can someone please help me prove how many exist?

A point P in the interior of a convex polyhedron in Euclidean space is called a pivot point of the polyhedron if every line through P contains exactly 0 or 2 vertices of the polyhedron. Determine, with proof, the maximum number of pivot points that a polyhedron can contain.


What is the difference between following 2 sentences? Can you please explain me the meaning of both?   "I have eaten my lunch" "I ate my lunch"   Thanks a lot for helping.

Non-native speakers often get confused about what the various tenses  and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter.  I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be  incorporated into the diagram.    Nota bene: What this is not is a discussion of whether there are  more than two tenses in English. , to which this question is not intended to supply arguments one way or the other.  Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better.  Breaking News There is now an excellent ELU blog article titled  . It is highly recommended reading.


I have an example dataset where a section has fields beginning with "something".  I would like to obtain all of the lines in each "something" section when matching a specific string of "1234".  I was thinking that I could search for "1234" and print all lines before and after until matching "something".  Desired output:  something like this one  1234  abcd  something like this one  zyxw  1234    Example dataset:  otherthings otherthings otherthings  something like this one  1234  abcd   something not like this one  xxxx  yyyy   something not like this one  xxxx  yyyy  something like this one  1234  abcd  otherthings otherthings otherthings

Using just shell script, how to search a text file and list all whole blocks of lines that has inside some text (simple grep criteria).   The text file has blocks of lines separated by "-----------------" (precisely, each block start with "\n\n\n--------------------"... about 50 chars "-").  A sample could be:  ------------------------------- Abracadabra, blablablalbalba blablablabla, banana    ------------------------------- Text, sample text, sample text, sample text Text, sample text, sample text, sample text Text, sample text, sample text, sample text Text, sample text, sample text, sample text   -------------------------------   Text, sample text, sample text, sample text banana. Sample text, sample text, sample text, sample text Text, sample text, sample text, sample text   Lets consider the word "banana" the search criteria. So, the blocks listed would be:  ------------------------------- Abracadabra, blablablalbalba blablablabla, banana   ------------------------------- Text, sample text, sample text, sample text banana. Sample text, sample text, sample text, sample text Text, sample text, sample text, sample text   EDIT:  Testing answers to try awk, like: awk 'BEGIN{RS="\n------------"}/INFO/{print}' where INFO is what was searched for. I cannot get the whole block. So, follows a real sample and the result:  A REAL SAMPLE (including the first 3 new lines):      ------------------------------------------------- Diretório separado do nome o arquivo: adis, IWZLM (/home/interx/adis/src/IWZLM.SRC) Gerando rotina em linguagem C: (yla5 adis IWZLM -if) .INFO =>Rotina BLOQUEADA (status 'M'): Geracao ignorada (use -is para ignorar checagem do status)  [  OK-I ] IWZLM (adis) - Lista lay: Geracao ignorada do codigo em C.    ------------------------------------------------- Diretório separado do nome d arquivo: adis, ADISA (/home/interx/adis/src/ADISA.SRC) Gerando rotina em linguagem C: (yla5 adis ADISA -if) .ERRO: Falha inesperada  Compilando o programa: (ycomp adis ADISA -exe adis/exe/ADISA.temp.exe ) adis/exe/ADISA.temp.exe => adis/exe/ADISA  [  OK   ] ADISA (adis) - Menu A : Gerada e compilada com sucesso.    ------------------------------------------------- Diretório separado do nome o arquivo: adis, ADISD1 (/home/interx/adis/src/ADISD1.SRC) Gerando rotina em linguagem C: (yla5 adis ADISD1 -if) .ATENCAO: Definicao nao localizada  Compilando o programa: (ycomp adis ADISD1 -exe adis/exe/ADISD1.temp.exe ) adis/exe/ADISD1.temp.exe => adis/exe/ADISD1  [  OK   ] ADISD1 (adis) - Menu : Gerada e compilada com sucesso.   I cannot get the whole block, just the line containing "INFO", like a ordinary grep, either setting or not ORS:  $ cat file  | awk 'BEGIN{RS="\n------------"}/INFO/{print}'  .INFO =>Rotina BLOQUEADA (status 'M'): Geracao ignorada (use -is para ignorar checagem do status)   NOTES: It is the awk from AIX 7.1, not gawk.


I will be looking to create a Logo very shortly.  I am not formally educated in this principle, where I am self learning through a variety of online resources.  Through my learning, I have come across the term 'Golden Ratio' and the 'Golden Spiral'.  I have read and watched countless resources but my only taking is that the ratio is set at 1:1.618 and its purpose is to help inform the creation of something that is visually pleasing.  I understand how ratios and proportionality works.  Where I am at a loss, is on where and how these ratios and spirals are integrated into the design process.  Due to not actually getting anywhere with my understanding, I thought I would look at some images that claim to abide by these ratios and spirals.  Using Photoshop, I then placed the Spiral on top of the images as an overlay as follows ...       I understand the ratio of 1:1.618.  When it comes to the Grid approach, would I be right in saying that each Box is simply in proportion of its adjacent Boxes by a ratio of 1.618?  Does it matter where the Grids are and how many Boxes the image includes?  For example, I could place many more Boxes within the Grid approach, as long as they follow the 1.618 ratio?  Obviously, the more Boxes being added, the smaller they would have to be.    Assuming I have understood the Mathematics/Technicalities of the Golden Ratio Grid, I am still at a loss of its implementation.  What exactly should I look out for and what would I need to ensure was in each Box for example.  That still leaves the question ... How does the Spiral work?       Maybe its just the frustrations within but it often seems to be that many resources try and make the Spiral fit an image rather than the Spiral informing the ideation and creative process.   Any clarification, on this, would be greatly appreciated since I am at a loss at its usage.

The  is the stuff of legend () and is . My question is two-fold, really: Is the Golden Ratio really a good tool used in modern design (defined here as 20th century on forward), and if so, how often is it used outside of the aforementioned known uses?  EDIT: To @e100's first comment, examples of modern use of the Golden Ratio would be a great thing to add here if there any documented or arguably conclusive uses of it.


I want to populate a list view based on grid item click. If user clicks the first grid item I want to show the list view according to it. I have used a pre populate SQLite database here.  What I tried is , to get item click id in first activity and pass it to DB Class. This is what I'm getting when debugging the programme.   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.content.Intent.getExtras()' on a null object reference         at com.example.sra.hellosrilanka.DBAccess.getQuotes(DBAccess.java:51)         at com.example.sra.hellosrilanka.ContactView.onCreate(ContactView.java:29)   DBAccess Class:  public class DBAccess extends Activity { private SQLiteOpenHelper openHelper; private SQLiteDatabase database; private static DBAccess instance; String passedVar=null;  public DBAccess(Context context) {      this.openHelper =new HelloDatabase(context); }  public static DBAccess getInstance(Context context) {     if (instance == null) {         instance = new DBAccess(context);     }     return instance; }  public void open() {     this.database = openHelper.getWritableDatabase(); }  public void close() {     if (database != null) {         this.database.close();     } }    public List<String> getQuotes() {     List<String> list = new ArrayList<>();     Integer value;      Bundle extras = getIntent().getExtras();     String a = extras.getString("ID_EXTRA");       if(extras != null)     {         Cursor cursor = database.rawQuery("SELECT org_name FROM org_name WHERE category_id = \""+ a +"\"" , null);        /* Cursor cursor = database.rawQuery("SELECT org_name FROM org_name WHERE category_id="+a, null);*/        /*Cursor cursor = database.rawQuery("SELECT org_name FROM org_name WHERE category_id='ID_EXTRA'", null);*/         cursor.moveToFirst();         while (!cursor.isAfterLast()) {             list.add(cursor.getString(0));             cursor.moveToNext();             cursor.close();         }     }    /*  if (passedVar != null) {       }*/      return list; }}   Contact View Class:  public class ContactView extends Activity { private ListView listView;  @Override protected void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);     setContentView(R.layout.list_view);       this.listView = (ListView) findViewById(R.id.listView);     DBAccess databaseAccess =  DBAccess.getInstance(this);     databaseAccess.open();     List<String> quotes = databaseAccess.getQuotes();     databaseAccess.close();      ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, quotes);     this.listView.setAdapter(adapter);  }   }  Main activity class  public class MainActivity extends AppCompatActivity {  GridView grid; Toolbar toolbar; private ListView listView;  String [] result; Context context; @Override protected void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      grid = (GridView) findViewById(R.id.grid);      toolbar=(Toolbar)findViewById(R.id.toolBar);    setSupportActionBar(toolbar);     grid.setAdapter(new CustomAdapter(this));             grid.setOnItemClickListener(new AdapterView.OnItemClickListener() {                 @Override                 public void onItemClick(AdapterView<?> parent, View v, int position, long id) {                     /*Intent intent=new Intent(MainActivity.this,ContactView.class);                     intent.putExtra("catid", id);                     startActivity(intent);*/                      Intent i=new Intent(MainActivity.this ,ContactView.class);                     i.putExtra("ID_EXTRA",String.valueOf(id));                     startActivity(i);                  }                 });}}

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


I've found several posts about mass installing Linux packages with one command , , and .  Here's my situation. I'm in a 3rd-world country right now with limited internet access. I want to know if there's a way to download a bunch of packages, store them somewhere, and write a little bash script to mass install them.  Is there a website that has a repository where I can do a one-time download of these permanently instead of having to use a bunch of data doing "apt-get" every time I try out a fresh installation of a Linux distro?  After I download these is there a way I can easily install them all these deb or tar files by writing a little bash script?

How do I install a .deb file via the command line?


I have a table with statistic of games which has next rows (I only write about rows that has interest in this context):  id        BIGINT PRIMARY KEY date      TIMESTAMP WITH TIME ZONE status    VARCHAR  -- 'WON' or 'LOSE' player_id BIGINT   -- FOREIGN KEY   I need to write a query that select number of consecutive win games (status = 'WON') by some user (user_id = %some id%).

I am trying to construct a query in PostgreSQL 9.0 that gets the longest sequence of continuous rows for a specific column.  Consider the following table:  lap_id (serial), lap_no (int), car_type (enum), race_id (int FK)   Where lap_no is unique for each (race_id, car_type).  I would like the query to produce the longest sequence for a given race_id and car_type, so it would return an int (or long) that is highest.  With the following data:  1, 1, red, 1 2, 2, red, 1 3, 3, red, 1 4, 4, red, 1 5, 1, blue, 1 6, 5, red, 1 7, 2, blue, 1 8, 1, green, 1   For car_type = red and race_id = 1 the query would return 5 as the longest sequence of the lap_no field.  I found a similar question  however my situation is a bit more straightforward.  (I would also like to know the longest sequence for a given car_type for all races, but was planning to work that out myself.)


Installing Ubuntu Desktop 14.04.1 from scratch, onto a 128GB SSD drive, I got three partitions by the installer's autonomic decision. I have not configured partitions myself during the installation nor have I opted for LVM.  The partitions are:   Bootable partition 86GB Ext4 (/dev/sda1)   Extended partition 34GB (/dev/sda2)  Swap partition 34 GB Swap (/dev/sda5)   Can I later remove the second partition and add its space to either the first or third ones? how disruptive would that operation be?

I started installing Ubuntu by watching a video tutorial about doing a disk partition installation, for that, inside Windows' 7 own disk partitioning tool. After a defrag I cut 100GB that I pretended to use on my Ubuntu installation for a little try out, now, while installing, I never really chose where I wanted Ubuntu to be installed, so I guess it just made a partition by itself of the minimum that the installation tells you it needs.  How can I now give the other 92 GB I had left apart only for that task?  Here's what my partitions look like now.     Here's a df:    And here's the GParted tool un ubuntu:


I already tried fixing it with margin, table styles, and the bootstrap css but it isnt working  I need the A tags to center in the label-row-overview div and be responsive  HTML

EXTRA FOTO'S

MAATTABELLEN

PRODUCT SPECS

CERTIFICATEN

   Style.css  .label-row-overview a {   color: #FFF;   background-color: #12a19b;   padding: 10px;   display: inline-block;   margin: 5px;   overflow: hidden; }

How can I horizontally center a
 within another
 using CSS?

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