How to be more polite and accommodating? Here's my beef. I've noticed over the past couple of days, and even before I joined this (the StackExchange) community that most of you aren't kind to your fellow user. I'm not trying to get up on a soap-box here, I'm just calling things how I see them.  For instance (and this is an issue throughout the various communities here, not just one particular one) - you all seem to be trigger happy when it comes to flagging duplicates. I think this practice is wrong, not to mention unethical. Here's why:  I speak Spanish as a second language and know that the words 'por' and 'para' are very hard for Spanish learners to understand and grasp, due to their variant meanings, sometimes by the sentence, sometimes by the word pair, and sometimes by the country in which they are used. So it's very important that a variety of examples are given to help teach students of the language what they mean, when, and how.  This means that no question is a stupid question, and no question is a duplicate question, necessarily. For example, in the two sentences below, the word 'por' means virtually the same thing, but without the context, word pairs, or phrasing, it changes completely.   Anya nadó por el canal en junio.   Translates to: Anya swam the canal in June. (As in, she swam through it.)  Anya nadó por el canal en junio.   Translates to: Anya swam by the canal in June. (As in, she swam near it, but not in it.)    The two sentences are completely different, but also completely the same. If the reader of the question doesn't pay attention to context (like they say they do, and as they seem to put so much emphasis on), you might end up with a wrong translation to English or whatever language it is they [the asker] speak fluently and understand best.  For instance, in some languages, 'where' is a place, more so than  as it is currently used. In some languages, the word 'it' is part of other words or implied from context, so English learners may not write them out since it makes sense not to in their language. Other times, they just have a bad teacher who they themself doesn't understand the language they're teaching, and thus gives them bad translations from the get-go.  If you want real-life examples from StackExchange, you can search for such things as 'the difference between' and ' to say this ...?' on the appropriate forums. There are about ten or so more different variations for each question, but they are just that - variation. They are not the same question. Each question should be handled individually based on the phrasing, not the content.   In other words, you need to analyze how how is being used, because it has a lot of different meanings, and what you think the asker means may not be what they mean at all.   This also happens with StackOverflow, for example. I'm not the best coder, so I often want to ask the reason why something is done, but I avoid doing so at the risk that my question might be closed, neglected, or made fun of by more experienced (even professional) coders who might go, "Well, duh. Of course you should put "" after div, it just makes sense. It's what you do." Well, why? Don't just tell me it's how the computer reads it. I don't care about that, really. I know the computer reads it because it's code, duh! Why does it read it that way? Why not another? How is it useful?  The snarky comments don't make it any fun or more helpful than say, Yahoo!Answers with its simplistic format and network. Don't people come to SE for more information, preferably high-quality?  So my question is thus: How can we improve site features and user etiquette among other things to make the experience better for everyone?
Could we please be a bit nicer to new users? There is a distinct decline in the level of civility on all the sites here.  Some of this is due to new users coming in and posting spam and other nonsense, but the off-topic and downvote buttons are doing a pretty good job of keeping this under control. Unfortunately, a lot of this is coming from more experienced users, and the site's built-in moderation system does not (and probably cannot) handle this very well.  Folks are rushing to pound new users down with &quot;this belongs on meta!&quot;, &quot;this is off topic&quot;, &quot;this is a duplicate!&quot; and &quot;read the Help!&quot;. (Which is correct, but should be done nicer) All this, of course, is accompanied by a flurry of downvotes.  This is not very welcoming to new users who don't know about meta, the Help, or what counts as off-topic. Now I am not proposing that we just allow off-topic, meta, or duplicate questions.  However, I think we could be gentler in the way we express these sorts of things.  Explain what meta and the FAQ are and provide useful links.  Just using please and thank-you when asking folks to read the FAQ or post something on meta would be an improvement.  I also think we could rein in the downvoting a bit.  Not that we shouldn't vote stuff down, but unless a new user's post is clearly spam, voting it down to -1 or -2 should be sufficient to send a message without piling on. I like Stack Exchange and I want it to become a resource for everyone, not just an elitist site for high-rep users on the sites.
Right triangles and tangent lines Consider the hyperbola $xy=1$ with $x&gt;0$ and $y&gt;0.$ The tangent line at any point on the hyperbola forms a right triangle with the coordinate axes. Show that the area of the triangle does not depend on the point chosen. To show this, do the following:      a) Choose a point on the hyperbola of your choice. Find the tangent line and then find the area of the right triangle described above.      b) Choose a different point of your choice. Find the tangent line and then find the area of the right triangle described above.      c) Now for the general case, choose the point at $x=a.$ Find the tangent line at $x=a$ and then find the area of the right triangle described above.   This is the work I have so far:    No method to find the area of a right triangle was given, so I just used 1/2*B*H.  But I get stuck when given $x=a$ for part C.  Any ideas? Removing small spaces (slivers) between polygons? Questions about a commutative ring with exactly three ideals Let $R$ be a commutative ring with identity. Assume that $R$ has exactly three distinct ideals: $\{0\},I, R.$      1) Show that if $a \in R-I$, then $a$ is a unit in $R$.      2) Let $a,b\ne0$ in $I$. Show that $ab=0$. How can I mitigate edge halo when darkening skies in post-processing? Page title with substitution on views page I have a view page that requires a dynamic page title. It is a simple substitution of the label field.  If I use {{ label }} it works fine for the title displayed on the page, but it doesn't substitute the label for the actual page title (in meta)  I was able to fix this by using hook_views_post_render using the following code  // Set the route title. $route = \Drupal::routeMatch()-&gt;getCurrentRouteMatch()-&gt;getRouteObject(); $route-&gt;setDefault('_title', $title);  $view-&gt;setTitle($title);   However, the title only works if the page is not cached. For the cached pages, the page title is missing. This feels like a bug in drupal, but I am hoping that there is a simple way to get this done. Recently a few friends and I came up with an idea for an app. To facilitate the creation of it, we set up LAMP on an Ubuntu Server 12.04. This box is running from my home. We've set up 3 user accounts. I'm still pretty new to Linux, but I have a bit of experience from using Ubuntu on my own box.  Today I was playing around with SSH and looking at the logs (I need to learn how to read that information to know how the server is performing, right?) and I saw the strangest thing.  In /var/log/auth.log and /var/log/auth.log.1 I saw a bunch of failed login attempts for 'root' and a few usernames I'm not familiar with. I looked over them and for as far as I can see no user has been authenticated except for the actual users on the system. A lot of the IP-addresses listed seem to be from Russia.  As of now this server contains nothing but a vanilla Ubuntu Server with LAMP, but even so, with the following command:  sudo grep -i fail /var/log/auth.log | wc -l   I get 3412 as a result. This seems very excessive for a server that has been up since April 8th. It gets worse, because running the above command on auth.log.1 returns 23075 (!!!!) results.  It seems obvious that people are trying to break into the server. Not that it contains anything of value, but once we start making progress on the app we wouldn't want our intellectual property stolen.  Should I be worried? And what can I do about it?  EDIT:  I found some very useful information  and this allowed me to run a script that splits and sorts all the invalid passwords and invalid users that tried to log in. May come in handy to someone who ended up here through Google! How to pick one number from each sorted list so that the difference between the minimum and maximum is as small as possible? Why didn't Doc remember Marty's outfit? In Back to the Future 3, Doc (from 1955) sends Marty back in time wearing a cowboy outfit.  But then, Doc (from 1885) doesn't remember that it was him who offered this outfit to Marty.   Does this mean there are two different Docs (from differing timelines) or is it the same Doc but he somehow forgot the outfit. Writing test code for wrapper class I created a controller which looks like this  public with sharing class EventRegistrationController {      // A CONTROLLER FUNCTION     // FUNCTION RETURNS A LIST OF cSession      public List&lt;cSession&gt; getSessions() {            //DO STUFF       }     //A PUBLIC CLASS WITHIN CONTROLLER    @TestVisible public class cSession      {         public Session__c con {get; set;}         public Boolean selected {get; set;}          //This is the contructor method.          public cSession(Session__c c) {              con = c;             selected = false;         }     }  }   I need to write a test code for the controller, how can I create a list of cSession and call getSession function? Given $\int_0^{\infty}e^{-x^2}dx = \frac{\sqrt{\pi}}{2}$, evaluate $\int_0^{\infty}e^{-a^2x^2-\frac{b^2}{x^2}}dx $ Given $$\int_0^{\infty}e^{-x^2}dx = \frac{\sqrt{\pi}}{2}$$ evaluate:   $$\int_0^{\infty}e^{-a^2x^2-\frac{b^2}{x^2}}dx. $$   I can find that  $$\left(ax+\frac{b}{x}\right)^2 = a^2x^2+2ab+\frac{b^2}{x^2}$$  therefore: $$\int_0^{\infty}e^{-a^2x^2-\frac{b^2}{x^2}}dx = e^{2ab}\int_0^{\infty}e^{-\left(ax+\frac{b}{x}\right)^2}dx$$  but I can't find any clue then. In my program I have one array with 25 double values 0.04 When I try to sum these values in a loop I get following results:  0.0 + 0.04 = 0.04 0.04 + 0.04 = 0.08 0.08 + 0.04 = 0.12 0.12 + 0.04 = 0.16 0.16 + 0.04 = 0.2 0.2 + 0.04 = 0.24000000000000002 0.24000000000000002 + 0.04 = 0.28 0.28 + 0.04 = 0.32 0.32 + 0.04 = 0.36 0.36 + 0.04 = 0.39999999999999997 0.39999999999999997 + 0.04 = 0.43999999999999995 0.43999999999999995 + 0.04 = 0.4799999999999999 0.4799999999999999 + 0.04 = 0.5199999999999999 0.5199999999999999 + 0.04 = 0.5599999999999999 0.5599999999999999 + 0.04 = 0.6 0.6 + 0.04 = 0.64 0.64 + 0.04 = 0.68 0.68 + 0.04 = 0.7200000000000001 0.7200000000000001 + 0.04 = 0.7600000000000001 0.7600000000000001 + 0.04 = 0.8000000000000002 0.8000000000000002 + 0.04 = 0.8400000000000002 0.8400000000000002 + 0.04 = 0.8800000000000002 0.8800000000000002 + 0.04 = 0.9200000000000003 0.9200000000000003 + 0.04 = 0.9600000000000003   Why on earth could that happen?! Matrix is conjugate to its own transpose Mariano mentioned somewhere that everyone should prove once in their life that every matrix is conjugate to its transpose.  I spent quite a bit of time on it now, and still could not prove it. At the risk of devaluing myself, might I ask someone else to show me a proof? The square of an integer is congruent to 0 or 1 mod 4 This is a question from the free Harvard online abstract algebra .  I'm posting my solutions here to get some feedback on them.  For a fuller explanation, see  post.  This problem is from assignment 6.  The notes from this lecture can be found .     a) Prove that the square $a^2$ of an integer $a$ is congruent to 0 or 1 modulo 4.   b) What are the possible values of $a^2$ modulo 8?   a) Let $a$ be an integer. Then $a=4q+r, 0\leq r&lt;4$ with $\bar{a}=\bar{r}$.  Then we have $a^2=a\cdot a=(4q+r)^2=16q^2+8qr+r^2=4(4q^2+2qr)+r^2, 0\leq r^2&lt;4$ with $\bar{a^2}=\bar{r^2}$.  So then the possible values for $r$ with $r^2&lt;4$ are 0,1.  Then $\bar{a^2}=\bar{0}$ or $\bar{1}$.  b) Let $a$ be an integer. Then $a=8q+r, 0\leq r&lt;8$ with $\bar{a}=\bar{r}$.  Then we have $a^2=a\cdot a=(8q+r)^2=64q^2+16qr+r^2=8(8q^2+2qr)+r^2, 0\leq r^2&lt;8$ with $\bar{a^2}=\bar{r^2}$.  So then the possible values for $r$ with $r^2&lt;8$ are 0,1,and 2.  Then $\bar{a^2}=\bar{0}$, $\bar{1}$ or $\bar{4}$.  Again, I welcome any critique of my reasoning and/or my style as well as alternative solutions to the problem.  Thanks. Do users get notifications when @ was edited in SQL MAX of multiple columns? Test if a string contains any of the strings from an array Uneven movement on camera following a path. I render a short movie. I set the camera to the circle curve to make it fly in circle. The problem is after render, the camera is a little shaky. Can anyone help me? Thanks first. Where do deleted items go on the hard drive? Solving linear congruence (modular inverse or fraction) via gcd Bezout equation Isn't finding the inverse of $a$, that is, $a'$ in $aa'\equiv1\pmod{m}$ equivalent to solving the diophantine equation $aa'-mb=1$, where the unknowns are $a'$ and $b$? I have seem some answers on this site (where the extended Euclidean Algorithm is mentioned mainly) as well as looked up some books but there is no mention of this. Am I going wrong somewhere or is this a correct method of finding modular inverses? Also can't we find the Bézout's coefficients by solving the corresponding diophantine equation instead of using the extended Euclidean Algorithm? Why do first years cross the lake to get to the castle?