System.Threading.Timer vs System.Threading.Thread.Sleep resolution - .NET Timer not using system clock resolution
Why are .NET timers limited to 15 ms resolution?
How do I change the extension of multiple files? Why is this power adapter transformerless? Long site name hides the diamond in profile page Communities I want to reinstall Ubuntu, but I also want all information and settings to disappear. So everything looks like the first time I installed it. Is it possible to do so via Terminal? Or what are the steps I should follow? `du -b` shows different size than `ls` Rounded corners in TikZ trees. How to get distance when acceleration is not constant? I have some files that Ubuntu can't read it ( ANSI encoding ) but Windows can read it well.  When I open it in gedit or notepad++ it seems like this :     Êã ÇáÊÍæíá áÜÜ   How can I make Ubuntu read ANSI encoded files well? How to prove Fibonacci sequence with matrices? Using Illustrator CS6 to create shape out of multiple paths Can someone explain me this  please I am a bit confused?  It's from a texbook I am reading (block cipher companion)  it says that:      each weak key has  $2^{32}$ fixed points $m$ where $\operatorname{DES}_w(m) = m$ ( $w$ is a DES weak key). In other words encrypting a fixed point gives exactly the same point. To see this consider the $2^{32}$ ciphertexts after 8 rounds of encryption for which the two 32 bit halves are equal. For a weak  DES key, the round keys of the eighth and ninth rounds are equal. Thus the intermediate texts after seven rounds and after nine rounds of encryption will be equal. Since the round keys of the 7th and the 10th rounds are equal, the intermediate texts after 6 rounds and after 10 rounds of encryption will be equal. Continuing like this it follows that the plaintext will be equal to the ciphertext.    Now did not quite get :   Why are there $2^{32}$ fixed points?  And why after the eighth round of encryption the two halves must be equal? What does the author mean by the intermediate texts exactly? And how are they being equal?   P.S.: This question is not asking for what the weak keys are. I am asking for "fixed points" not exactly weak keys. For this reason I think it is not a duplicate of any other question. There is one similar question to what I've asked for which I have checked and saw that no satisfactory answer has been given there either.  Here is the similar question with no proper answers: Parser for C# Which parsers are available for parsing C# code?  I'm looking for a C# parser that can be used in C# and give me access to line and file informations about each artefact of the analysed code. How to extract img src, title and alt from html using php? I would like to create a page where all images which reside on my website are listed with title and alternative representation.  I already wrote me a little program to find and load all HTML files, but now I am stuck at how to extract src, title and alt from this HTML:  &lt;img src="/image/fluffybunny.jpg" title="Harvey the bunny" alt="a cute little fluffy bunny" />  I guess this should be done with some regex, but since the order of the tags may vary, and I need all of them, I don't really know how to parse this in an elegant way (I could do it the hard char by char way, but that's painful). Projectile/orbital motion over very long distance We know the optimum angle for greatest horizontal displacement when launching an object with projectile motion is 45 degrees.  How to solve the angle when it is real long distance around the earth where we cannot assume that gravity is constant but is given by $F=\frac {-GMm}{r^2}$. I use differetial equation to solve it and obtain 45 degrees.   First, for the vertical distance $y$, change $v=u-gt$ to $y'=u-y''t$. Then solve it to obtain a function $y(t)$. When $y'(t)=0$ we have the time for maximum vertical distance. Then insert the value to horizontal equation.   Can anyone guide me through this problem because I am not confident with my working Correct usage of "persons" (vs. "people") I had a little fight about persons vs. people.  Could you advise if both of the following are correct, if possible with reference to a dictionary?        A table for two people please.   A table for two persons please.      Besides that, how would you ask for a table in a restaurant?  I read  and , but they didn't really solve the question if both are correct.  I also found the last paragraph of , which suggests that (1) is "more correct", but doesn't say (2) is wrong. I run sudo apt-get install git-all in Ubuntu 16.04 and see the following in the end  Setting up runit (2.1.2-3ubuntu1) ... start: Unable to connect to Upstart: Failed to connect to socket /com/ubuntu/upstart: Connection refused dpkg: error processing package runit (--configure):  subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of git-daemon-run:  git-daemon-run depends on runit; however:   Package runit is not configured yet.  dpkg: error processing package git-daemon-run (--configure):  dependency problems - leaving unconfigured No apport report written because the error message indicates its a followup error from a previous failure.                       Errors were encountered while processing:  runit  git-daemon-run E: Sub-process /usr/bin/dpkg returned an error code (1)   I get the error after rebooting my system also. It really blocks my whole system.  I run killall update-notifier. I run sudo apt-get install git-all but  I get the same error message. I run pgrep -a apt but get nothing as output. I run pgrep -a update but get nothing as output.  A bug report about the case .    In Grub, Choose Advanced options > Ubuntu (Upstart) Linux kernel 4.22. Doing the same only in terminal without systemd causes the same error.      Why is this error here with runit? Find a plane that passes through a point and is perpendicular to 2 planes Find an equation of a plane that passes through $p(1,5,1)$ and is perpendicular to planes $2x+y-2z = 2$ and $x+3z=4$.  I basically need the 2 other points to make the vector and perform the cross product.  Since $ax+by+cz+d=0$ is the form of a plane. Can I obtain the points as $(a,b,c)$ of the 2 planes given? Also, how can I set them up to obtain the points? How come the year doesn't show here? Prove that :  $$ \frac{\sqrt{\pi}}{2} e^{-\frac{a^2}{4} } =\int_0^{\infty} e^{-x^2} \cos( a x) \ \mathrm{d}x$$    the only thing I can think of is differentiating the RHS and trying to get :  $$ -2 f'(a) =a f(a) $$ But I couldn't do it.  Can anyone show me how to do this ? Why does a wireless network give a more accurate location than a wired network? I build a simple HTML5 website that takes my location (in latitude-longitude), and simply shows my location in Google maps.  I opened the HTML document with my laptop Asus K53E-B1 and I found that when I connected to a wireless network, it showed almost my precise location (about 100 meter of inaccuracy),  while when I plug in the network cable, and test again, it's a bit Inaccurate. (showed a street 12KM away from me).  Can you explain me why is a wireless network gives more accurate location?  Tested with Google Chrome.