Exercise of spaces path connected
$\mathbb{R}$ \ $\mathbb{Q}$ and $\mathbb{R}^2\setminus\mathbb{Q}^2$ disconnected?
Additional Drivers for Ubuntu 17.10 The Additional Drivers settings interface is no longer available in Ubuntu 17.10  How can I install proprietary drivers in Ubuntu 17.10?  I need drivers for Wifi &amp; Bluetooth (BCM43142) and Intel Graphics.  The earlier Additional Drivers program showed a package named jockey but it no longer seem to exist in repositories. Using the method of characteristics, find a solution to Burgers' equation    \begin{cases} u_t+\left(\frac{u^2}{2} \right)_x =0 &amp; \text{in }\mathbb{R}\times(0,\infty) \\ \qquad \qquad \, \, u=g &amp; \text{on } \mathbb{R} \times\{t=0\} \end{cases}   with the initial conditions    $$g(x)=\begin{cases} 0 &amp; \text{if }x &lt; 0 \\ 1 &amp; \text{if }0 \le x \le 1 \\ 0 &amp; \text{if }x &gt; 1 \end{cases}$$   First, I realized that the equation $u_t+\left(\frac{u^2}{2} \right)_x =0$ is equivalent to this form: $$u_t+uu_x =0$$  Then should I generally follow the method of solution as outlined in the answer of ?  Note that this is not a duplicate question of that page. Rather I want to know if that page can be used for my problem, even though my ICs are different.  By the way, the solution printed in my book (PDE Evans, 2nd edition, page 142) is      $$u(x,t) =  \begin{cases} 0 &amp; \text{if } x &lt; 0 \\  \frac xt &amp; \text{if } 0 &lt; x &lt; t  \\ 1 &amp; \text{if } t &lt; x &lt; 1 + \frac t2  \\ 0 &amp; \text{if } x &gt; 1 + \frac t2 \tag{$0 \le t \le 2$}  \end{cases}$$ I got a bash script to synchronize data between two computers. It works fine but I have to type my password every time the rsync command is called.   #!/bin/bash  sourceIP="192.168.178.128" sourceUser="user1" destinationUser="user2"  function sync() {      rsync --archive --progress -v -e "ssh -l $sourceUser " $sourceIP:/home/$sourceUser/$1/ /home/$destinationUser/$1 }  sync Pictures sync Music sync Videos sync Documents   How to store the password (via prompt) in a variable and pass it to rsync/ssh? What are Harry, Ginny, Ron and Hermione's professions? Suppress SSL warnings MapServer (MS4W) test page from shapefile shows only blank white square? I am trying to create a test page with mapserver and shapefile. At the moment I just want to get the map shown on my test page. I have gotten the EXTENT coordinates by opening shapefiles with QGIS - I am sure those are correct. I have followed this  as an example.  I am accessing my test page via this link:  http://localhost:1025/cgi-bin/mapserv.exe?map=C:\MS4W\ms4w\Apache\htdocs\mapfile.map   Problem I have - map is not loaded - I only see a blank white square.  When I look at contents of ms4w\Apache\htdocs\output , I see that images are actually getting generated but all of them are white (empty), for example:  lat_pmts_region13941906093724.png lat_pmts_region13941910095144.png lat_pmts_region13941913405500.png ...   Shapefiles are located at this location: C:\MS4W\ms4w\Apache\htdocs\shapefiles.  An example of what is logged to error file:  [Fri Apr 11 11:19:32 2014].883000 CGI Request 1 on process 7888 msWCSDispatch20(): wrong service (none) msWCSParseRequest(): request is KVP. msWCSDispatch(): SERVICE and REQUEST not included msDrawMap(): rendering using outputformat named png (AGG/PNG). msDrawMap(): WMS/WFS set-up and query, 0.000s msDrawMap(): Layer 0 (lat_pmts_region), 0.001s msDrawMap(): Drawing Label Cache, 0.000s msDrawMap() total time: 0.002s msSaveImage(C:/MS4W/ms4w/Apache/htdocs/output/lat_pmts_region13972043727888.png) total time: 0.138s [Fri Apr 11 11:19:33 2014].24000 mapserv request processing time (loadmap not incl.): 0.141s [Fri Apr 11 11:19:33 2014].24000 msFreeMap(): freeing map at 0246EFD8.   ms4w\Apache\htdocs\template.html:  &lt;html&gt; &lt;head&gt;&lt;title&gt;Mapserver Template HTML Document&lt;/title&gt;&lt;/head&gt; &lt;body bgcolor=#AAAAAA&gt; &lt;h2&gt;Template&lt;/h2&gt; &lt;img src="[img]" border=1&gt; &lt;/body&gt; &lt;/html&gt;   It looks like this:   C:\MS4W\ms4w\Apache\htdocs\mapfile.map:  MAP     CONFIG "MS_ERRORFILE" "C:/MS4W/ms4w/tmp/ms_error.txt"     DEBUG 5     NAME lat_pmts_region     STATUS ON     SIZE 800 600      EXTENT 286878.53 142087.25 799084.10 481123.75     #   lat_pmts_region      UNITS METERS     SHAPEPATH "shapefiles"     IMAGECOLOR 155 155 155      WEB     TEMPLATE "template.html"     IMAGEPATH "C:/MS4W/ms4w/Apache/htdocs/output/"     IMAGEURL "/output/"     END      LAYER     NAME "lat_pmts_region"     DATA lat_pmts_region     STATUS DEFAULT     TYPE POLYGON     END END   I will gladly provide more information if it's asked. Given a method signature:  public bool AreTheSame&lt;T&gt;(Expression&lt;Func&lt;T, object&gt;&gt; exp1, Expression&lt;Func&lt;T, object&gt;&gt; exp2)   What would be the most efficient way to say if the two expressions are the same? This only needs to work for simple expressions, by this I mean all that would be "supported" would be simple MemberExpressions, eg c => c.ID.  An example call might be:  AreTheSame&lt;User&gt;(u1 =&gt; u1.ID, u2 =&gt; u2.ID); --&gt; would return true How to copy modifiers with attribute values from active object to selected objects with python scripting? Electric Potential produced by Hollow Sphere Let there be a hollow sphere (Throughout the question we will ignore the thickness of the sphere) which is positively uniformly charged,q of radius,  R. Suppose there to be a test positive charge, q' at point P which is r distance away from the hollow sphere(r>R, P is outside of hollow sphere).  Now I have an doubt on evaluating Electric Potential,V at point P.  Both source charge,q and test charge,q' are +ve, so source charge will repel the test charge which will make the charge, q' to go to infinity.I have to apply external force, F' to displace the charge, q' from infinity to point P against the equal but repulsive force, F.In short, F' is  displacing the q' from infinity to P.  So External Force, F' will do +ve work and Repulsive Force, F will do -ve work. This way the Electric Field,E produced by hollow sphere is Opposite to Displacement of test charge(i.e.,θ=180).  Now we know that E=k(q/(r^2))  [Please Notice that infinity is the lower limit of integration]  Also V=-∫r∞(E dr cosθ)=-∫r∞(E dr cos 180)=∫r∞(E dr)  At last I ended up to V=- k(q/r). I know that V=k(q/r).  I just want to know why I am having this shitty negative sign in my equation. Prevent abstract environment to reset pagenumbering In the  a line is delivered at around 1:41 where Han Solo says "a 190 years old!? You look great" and I was wondering if there is a defined concept of a year in the Star Wars universe or would Han Solo just be familiar with the duration of a  solar orbit. If $\sum_{n=1}^{\infty} a_n$ is absolutely convergent, then $\sum_{n=1}^{\infty} (a_n)^2$ is convergent What is the difference between the | and || or operators? I have always used || (two pipes) in OR expressions, both in C# and PHP. Occasionally I see a single pipe used: |. What is the difference between those two usages? Are there any caveats when using one over the other or are they interchangeable? Does the shape of a containter affect the apparent mass of liquid inside it when measured by a scale? For both containers it is true that:  $p_{bottom}=p_{atm}+\rho gh$ and $F_{bottom}=a*p_{bottom} \iff F_{bottom}=a*p_{atm} + a\rho gh$  I do not know how a scale functions, but I guess that the only force it can count is the force by the liquid on the bottom of each container (the only surface that is in touch with the scale is the bottom of the container). Thus, if we measured the mass of these two masses of water (lets assume that the mass of the containers is negligible) it would appear to be the same in each case. Am I right? Retrieving n rows per group I often need to select a number of rows from each group in a result set.  For example, I might want to list the 'n' highest or lowest recent order values per customer.  In more complex cases, the number of rows to list might vary per group (defined by an attribute of the grouping/parent record). This part is definitely optional/for extra credit and not intended to dissuade people from answering.  What are the main options for solving these types of problems in SQL Server 2005 and later? What are the main advantages and disadvantages of each method?  AdventureWorks examples (for clarity, optional)   List the five most recent recent transaction dates and IDs from the TransactionHistory table, for each product that starts with a letter from M to R inclusive. Same again, but with n history lines per product, where n is five times the DaysToManufacture Product attribute. Same, for the special case where exactly one history line per product is required (the single most recent entry by TransactionDate, tie-break on TransactionID. Limit position rigidbody How can I limit the position of a rigidbody, between two values ​​if I use this code:  public Vector3 dir;  Rigidbody rb;  void Awake() {     rb = GetComponent&lt;Rigidbody&gt;(); }  void FixedUpdate() {     rb.velocity = new Vector3(0f, 0f, 6f);      rb.AddForce(dir * 1f, ForceMode.VelocityChange); }   If I use Vector3.Clamp then the object will shake How is an instance initializer different from a constructor? How does Cooper get out of the black hole? In the movie Interstellar,  Cooper (played by ) enters a black hole and sends a message to Murph (his daughter). Later, he is found by rangers, but I don't understand how he gets out of the black hole?  As far as I know, nothing can get out of a black hole, as it has extremely high gravity. Good day guys, i have to something like this, any idea how is this picture made ?  so it looks like negative i did invert it in photoshop but the bright side of his face was blue, so there been negative effect and smting been used to change his face to blue before nagative or smting that changed his face to normal skin color after negative ? what can it be ? what do you guys think ? THANKS ! for help. This is an attempt to gather together the various questions about time that have been asked on this site and provide a single set of hopefully authoritative answers. Specifically we attempt to address issues such as:   What do physicists mean by time? How does time flow? Why is there an arrow of time?