Prove that $\pi$ is irrational
Help with proving that $\pi$ is irrational
Diamond is not shown for mod name under wiki posts If a diamond mod is an author of a wiki post then the diamond is not displayed besides the mod name. E.g. :        Even when the name refers to the user profile page (in case of more then one author) like in :        Is it intentional or a bug? Compile and install rtl8192cu driver Can someone help me with this problem ? I am new to Linux, so I do not know commands and I never did something like installing or compiling with command-line.  I bought WiFi adapter from Edimax, model EW-7811UN for my PC (not laptop, so I do not have wifi card, only ethernet). When I go through guide on CD, I came across a version of kernel. It said I need version 2.6, but I have 3.5.0-22-generic.   I got errors like I do not have file or folder etc. Can someone tell me where I can download compiled driver and where I need to put it? Or some other advice. I don't want downgrade kernel when it is not necessary. Multiple Inheritance #include&lt;iostream&gt; using namespace std;  class A  {    int a;    int b;    public:    void eat()    {       cout&lt;&lt;"A::eat()"&lt;&lt;endl;    } };  class B: public A {    public:    void eat()    {        cout&lt;&lt;"B::eat()"&lt;&lt;endl;     }  };  class C: public A {     public:    void eat()     {        cout&lt;&lt;"C::eat()"&lt;&lt;endl;     }  };  class D: public B, C {  };  int foo(A *ptr) {  ptr-&gt;eat();  } main() {  D obj; foo(&amp;(obj.B)); //error. How do i call with D's B part.  }   The above foo call is a compile time error.  I want to call foo with obj's B part without using virtual inheritance. How do i do that.   Also, in case of virtual inheritance, why the offset information need to be stored in the vtable. This can be determined at the compile time itself. In the above case, if we pass foo with D's object, at compile time only we can calculate the offset of D's A part. Proving $\lim_{x\to 1} x^3=1$ with $\epsilon$-$\delta$ definition Problem: I need to formally prove that $$\lim_{x\to 1} x^3 = 1.$$ My work: This is what I have so far and I'm generally a bit stuck with these proofs from here onwards. Because$$-\epsilon &lt; x^3-1 &lt; \epsilon  =  | x^3-1 | &lt; \epsilon,$$ then $$ -\epsilon &lt; x^3-1 &lt; \epsilon$$ $$-\epsilon+1 &lt; x^3 &lt; \epsilon +1$$ $$ \sqrt[3]{-\epsilon+1}&lt; x &lt; \sqrt[3]{\epsilon+1}.$$ Hoping that what I have done so far is correct. Am I right in thinking that $$ \sqrt[3]{-\epsilon+1}&lt; x &lt; \sqrt[3]{\epsilon+1}$$ is giving me an interval where $x$ is going to give me a $f(x)$ value that falls within the distance $\epsilon$ from the limit on the $y$-axis ? Or is this interval smaller than the $\epsilon$-distance on the $y$-axis? Assign z values to depth curves in QGIS I'm new to QGIS and working with GIS in general (student of architecture), so please bear with me.  I have obtained shapefiles with topographic curves of an ocean floor. My intention is to export these as CAD files and render as 3D models of the ocean floor in Revit. I have done this procedure earlier with terrain shapefiles. My problem now is that these files mapping depth does not contain z values, so when exporting them into CAD they are completely flat rather than 3D models.  The depth information in meter exists as attributes in the file (see attached image). What I want is to transform this depth value into real z coordinates for each line so that the curves have different heights when importing as CAD file in Revit.  Thankful for any pointers in the right direction. Plotting Population Regression Function with pgfplot I want the make the following population regression function with pgfplot.     My attempted code is  \documentclass[border=5mm]{standalone} \usepackage{pgfplots}   \begin{document}  \begin{tikzpicture}[ % Define Normal Probability Function declare function={             normal(\m,\s)=1/(2*\s*sqrt(pi))*exp(-(x-\m)^2/(2*\s^2));         }        ] \begin{axis}[     no markers   , domain=-3.2:3.2   , samples=100   , ymin=0   , axis lines*=left   , xlabel=     , every axis y label/.style={at=(current axis.above origin),anchor=south}   , every axis x label/.style={at=(current axis.right of origin),anchor=west}   , height=5cm   , width=12cm   , xtick=\empty   , ytick=\empty   , enlargelimits=false   , clip=false   , axis on top   , grid = major   , hide x axis   , hide y axis   ]    \addplot[cyan!50!black, rotate=-45] (x, {normal(0, 1)});  \end{axis}   \end{tikzpicture}  \end{document}     Any help to get this graph will be highly appreciated. Thanks Problem  sudo notify-send Test "Hello World"   Displays a notification as expected.  notify-send Test "Hello World"   Does not display a notification.  Further information  Ubuntu version 16.04.  The notifications appear to use notify-osd instead of notification-daemon. Running notify-send appears to launch a notify-osd process under the user that ran notify-send. I'm not sure what dbus is.   No error messages  There are no errors in the syslog. When I run the following code no error messages occur.   #include &lt;libnotify/notify.h&gt; #include &lt;stdio.h&gt; int main() {     gboolean x = notify_init ("Hello world!");     printf( "notify_init: %d\n", x );     NotifyNotification * Hello = notify_notification_new ("Hello world", "This is an example notification.", "dialog-information");     GError *err = NULL;     x = notify_notification_show (Hello, &amp;err);     printf( "notify_notification_show: %d\n", x );     if(err != NULL) {         printf("Error detected!\n");         printf("Error message:%s\n", err-&gt;message);     }     else {         printf("No error detected.\n");     }     g_object_unref(G_OBJECT(Hello));     notify_uninit();     return 0; }   I do not know what I'm doing. Thanks for the help.  Python Notify  In the past, I've used a python program that has working notifications. I tested a hello world notification and it works without sudo!   #!/usr/bin/env python # -*- coding: utf-8 -*- import gi gi.require_version('Notify', '0.7') from gi.repository import Notify  Notify.init("test") n = Notify.Notification.new('test', 'test2') n.set_urgency(Notify.Urgency.CRITICAL)     n.show()   Code from   I am not sure why this works. The python Notify is just wrapping the library used in the C example. I'd prefer not to use python but will if I must.  Edit  The problem occurred again. Resolved by adding urgency critical. class variable vs instance variable --Python What can I do if I forgot my Windows password? How do i create a linestring from points sort by date in PostgreSQL?  I tried:  SELECT observations.id,    ST_MakeLine(observations.geom ORDER BY observations.date) AS newgeom    FROM   observations     GROUP BY    observations.id;   This is going wrong. It returns me a linestring with same coordinates.  So, instead of a line from a to b, it gives me a to a.    What am I doing wrong? How to write a Hello World application in Java? Why do backslashes appear twice? What's the difference between eq, eql, equal and equalp, in Common Lisp? What's the difference between eq, eql, equal and equalp, in Common Lisp?  I understand that some of them check types, some of them check across types an all that, but which is which?  When is one better to use than the others? Why is it that   $$\lim_{n \rightarrow +\infty} \left( 1 + \frac{\lambda}{n}+ o \left( \frac{1}{n} \right) \right)^n = e^{\lambda}$$  I once remembered the justification for "ignoring" the $o(1/n)$ but can't recall it again. How to get a list of the filenames of the figures embedded in a document I have a TeX document that is embedding a huge amount of figures from a fig folder that is full of another humongous amount of other figures.  I would like to move the document along with its figures, but I don't want to take the whole fig folder, just the figures in there that are embedded by the document.  Is there a package (or any other way) that allows me to, for example, print out the filenames of all the figures embedded by the document? Something like:  fig/figurename1.eps fig/figurename2.eps ... etc   I could then just copy-paste that list and add some cp's in a plain text file and automate the copy of those files to my desired location by running the file in my shell:  $ cp fig/figurename1.eps wherever/fig/ $ cp fig/figurename2.eps wherever/fig/ ... etc   Of course this is just an idea, if somebody has an alternative to the "file listing and copy-pasting in a shell file" I would be happy to listen =) Tags on badge question list I'm trying to get the Weed-Eater hat on Stack Overflow. To do so, I'm looking at the list of questions . The problem is, no tags show up there, and so it's rather difficult to see which ones I have a shot at. Any chance of showing the tags on this page?  I realize that getting this before Winter Bash is over would be difficult, but it would be good to keep such things in mind for the future. Can we re-request features that were declined a sufficient while ago? I can type:  dirname ~/home/blah/file.zip   for instance, and this works fine alone, but when I use this syntax as the parameter for some command it always reads 'dirname' as the desired directory. i.e.:  cd dirname ~/home/blah/file.zip bash: cd: dirname: No such file or directory   Basically, how do I get 'dirname file' to be read as one entity? Can I use older MySQL workbench with newest MySQL server? MySQL newbie here.  I'm using Ubuntu 16.04 (64-bit). I've successfully installed MySQL Community Server 5.7 and MySQL Community Workbench 6.3.  Unable to find these answers in the MySQL forums. I've asked this on Stack Exchange and it was suggested that I ask here instead. I've searched on Ubuntu Forum and here also but did not find an answer. One would think they are common questions but maybe not. Additionally, I cannot find a way to ask a new question on the MySQL Forum. I've spent a ton of time reading/researching/installing/uninstalling and reinstalling MySQL and community workbench on Linux Ubuntu 16.04 (64-bit) and do not want to lose the momentum I've gained. I'm actually making forward progress after a week or so of trial and error working on this up to a few hours per day. It appears that I cannot load MySQL Community Workbench 8.0 without Linux server installed. That seems to be one of the requirements if I understood correctly.  Can anyone tell me if MySQL Community Workbench 6.3 will work with MySQL Community Server 8.0 on Ubuntu 16.04 (64-bit)? I would still like to upgrade and use MySQL community server 8.0 if I can.  Can I use MySQL Community Server 8.0 on Linux Ubuntu 16.04 32-bit?   I've spent many hours googling it and looking on MySQL Forums but couldn't find the answer. Thanks much. ...Rick I created some linestring features in EPSG:32632 (WGS 84 / UTM zone 32N) exactly 10 000 m long.  QGIS calculates all line lengths (horizontal, vertical, diagonal) as 10 001.9 m. The measure tool explains "Project CRS transformation is turned on and ellipsoidal calculation is selected. The coordinates are transformed to the chosen ellipsoid (WGS84), and the distance is calculated in meters."  When I set the ellipsoid to "None / Planimetric" in project properties, I get the expected results (10 000 m).  I don't understand the phrase "coordinates are transformed to the chosen ellipsoid (WGS84)", is it a transformation to unprojected degrees (4326?)? Since 32632 already is based on WGS84, is there anything to transform? If there is a kind of "great circle" calculation involved, I would have expected lengths can only get smaller.  Is QGIS's calculation correct/meaningful, is it plain wrong or do I see rounding errors?  This are the geometries I tested:  LineString (370000 5615000, 370000 5625000) LineString (366464.46609406732022762 5616464.46609406732022762, 373535.53390593267977238 5623535.53390593267977238) LineString (365000 5620000, 375000 5620000) LineString (373535.53390593267977238 5616464.46609406638890505, 366464.46609406638890505 5623535.5339059317484498)   Edit as addition to MappaGnosis's answer: I forgot that in UTM , this seems to be the simple answer for the title question.