Why my 2 computers cannot ping one another?:
Why I cannot ping 192.168.0.108 (my computer IP?)
Where does the extra kinetic energy come from in a gravitational slingshot? I've heard Google's algorithm is based on PageRank, and that it has something to do with the links to your site. Can someone explain it, and more importantly, how I can increase my site's PageRank? How to show that the cohomology of a Grassmannian has a basis consisting of the equivalent classes represented by Schubert cycles? Let $G(r, n)$ be the Grassmannian of the set of all $r$-planes in a $n$-dim vector space. How to show that the cohomology of a Grassmannian has a basis consisting of the equivalent classes represented by Schubert cycles? I am confused since I don't know how to compute the cohomology of a variety (how to construct the co-chain complex). I am really appreciate if you can compute the cohomology of, for example, $G(2,4)$ and show that it has a basis consisting of the equivalent classes represented by Schubert cycles. align xticks in PGFPlots The text xticks are not placed on the same line, rather the same height counting from the highest letter (zero is much higher than high and low).    How can you fix this?  MWE:  \documentclass[class=scrartcl,14pt]{standalone} \usepackage{fontspec} \usepackage{luatex85} \usepackage{unicode-math} \usepackage{tikz} \usepackage{pgfplots,pgfplotstable} \usepackage{calc} \usepgfplotslibrary{groupplots} \pgfplotsset{compat=newest}  \begin{document}  \begin{tikzpicture} \begin{groupplot}[group style={group size=1 by 1, horizontal sep=2cm, xlabels at=edge bottom }, %~ yticklabel style={/pgf/number format/fixed}, %~ xticklabel style={/pgf/number format/fixed}, scaled y ticks = false, scaled x ticks = false, xtick pos=left, ytick pos=left, %xlabel=time (week) ] \nextgroupplot[xmin=0.5,xmax=3.5,xtick={1,2,3},ymin=2.43,ymax=3.05,xticklabels={zero, low , high}, xlabel={label}]  \end{groupplot}  \end{tikzpicture}  \end{document} Can the sum of the first $p$ factorials ever be a perfect power for $\ p>3\ $? Has $$\sum_{j=1}^p j!=q^r$$ , where q,p,r are positive integers, and r > 1 , a solution ?   I solved partially, if r is even, then RHS is a perfect square, and there is no doubt in that. Therefore, the left side must be a perfect square as well. But for p>3, the last digit of LHS is 3 which is not the last digit of any square. Hence, p&lt;4, and hence manually checking, only solutions are p =1,3. But i cannot generalize when r is odd.  Any solution to the next part would be helpful! How do I send a file as an email attachment using Linux command line? There appears to be a poltergeist in my speakers (no, really) I've no idea if there's a suitable Stack Exchange for poltergeists. It appears to be software, hardware or virus related, so I thought I'd try here, seeing as Ghostbusters is just a film, so I can't call them.  I'm not going mad, and this isn't a joke.  There's what appears to be a radio stream coming out of my speakers, except I can only hear it when the volume knob is turned down to the min setting whilst the speakers are on, which makes no sense. Sometimes it's French, which also makes little to no sense.  The speakers are Logitech 5.1s, I forget the model number, and I'm running XP 64bit. If that makes a difference.  I'd suspect it could be some sort of crazy virus, but I've been randomly killing processes whilst the poltergeist is active and it hasn't killed it, so I'm not sure about that.  Once again, I'm perfectly sane and this really isn't a joke. Perhaps other people have had this problem but have been too afraid of the reaction to ask anyone (please don't have me committed to an insane asylum).  Googling for strange noises coming from speakers didn't really get me anywhere. Has anyone heard of a virus that can do this and affect the volume controls on the hardware in that way? What's an atomic superstate/, and how is it possible?  I understand the basics - being something can be moving and staying still at the same time; the observer changes the behaviour - but I'd like to know a little more, as it interests me, and how is it possible without actually interfering with said thing? I saw a dog.       I have seen a dog.   What are the differences between them? Did these events happen on the same day? Prevent Adobe Reader from switching to "Fit Page" zoom when bookmark is clicked Is it possible to assign a base class object to a derived class reference with an explicit typecast in C#?.  I have tried it and it creates a run-time error. Help Understanding How Long It Will Take To Heat My Wire I just downloaded a DVD which is for a movie. After uncompressing the DVD file I see .VOB, .IFO and .BUP files. If I open the first .VOB file it shows me the DVD menu but I can't interact with it. So, my question is... is Totem able to play those kind of files? If so, how can I achieve that? What other app could I use in order to reproduce those files?  Edit  Using VLC didn't work neither. I forgot to mention I have already tried that. Let me rephrase: if I open the first video file it shows the DVD menu, BUT I can't interact with it. So Black Holes Actually Merge! In 1/5th of a Second - How? I've read a lot of conflicting answers in these forums. However, today saw the awesome announcement of gravitational waves. Two black holes merged:   Not only that, they merged FAST. In 1/5th of a second revolving around each other 250 times a second. The entire event was quicker than a heartbeat. Moreover, we observed this happening as distant outsiders. So now we can say for sure:   Objects approaching the event horizon DO NOT appear to slow down Black holes CAN merge in a finite (and quick) amount of time And all this is wrt a frame of reference far, far away   To quote the NYTimes article:  One of them was 36 times as massive as the sun, the other 29. As they approached the end, at half the speed of light, they were circling each other 250 times a second.  And then the ringing stopped as the two holes coalesced into a single black hole, a trapdoor in space with the equivalent mass of 62 suns. All in a fifth of a second, Earth time.  However, everything I've read so far has let me to believe that an outside observer should never be able to measure the collision happening in a finite time. So what exactly is happening here? I must have read at lest 5 different versions of this so far everywhere in these forums over the past several years. Doesn't the end of Looper create a time paradox? I guess this is more a question about the nature of time travel more than anything else.  At the end of the movie,      Joe shoots himself in a field and changes the course of history.   Does this create a paradox as it changes the history that led up to that point?      If his future self had never existed he'd never have gone on the mission he did and thus he never would have ended up in the field.   Once he did what he did, he could no longer have done it, and so theoretically, time and space should have just folded in on itself and popped out of existence.  Is there something I'm missing that would explain how the movie could have ended where it did without the events at the beginning to lead it there? I'm setting up an online ordering system but I'm in Australia and for international customers I'd like to show prices in US dollars or Euros so they don't have to make the mental effort to convert from Australian dollars.  Does anyone know if I can pull up to date exchange rates off the net somewhere in an easy-to-parse format I can access from my PHP script ?    UPDATE: I have now written a PHP class which implements this. . I could not install my modem driver so I have to update and install applications offline. For this I want to use keryx but to install keryx, Python and wxPython have to be installed first. So how do I install Python and wxPython offiline on Ubuntu 13.04?  Note : I don't have internet connection in Ubuntu. So I'll have to download the required file from my Windows 7. Install Windows 10 alongside Ubuntu 14.04 I have a dll that was written in c++, I need to use this dll in my c# code. After searching I found that using P/Invoke would give me access to the function I need, but these functions are defined with in a class and use non-static private member variables. So I need to be able to create an instance of this class to properly use the functions. How can I gain access to this class so that I can create an instance? I have been unable to find a way to do this.   I guess I should note that the c++ dll is not my code. Photo Map tip in QGIS 3 on windows