Is " Long time no see " Grammatically correct ?   So I use to talk to native English speakers and they use it usually so I want to make sure if it's grammatically correct ? or " I haven't seen you for a long time " should be used instead ?
I have researched and found out long time no see is a direct translate from the Chinese phrase, 好久不见. As much as we use it almost everyday in our lives, is it actually grammatically correct? Since it is a direct translate, is it grammatically approved?
Is it possible for some integer $n&gt;1$ that $2^n-1\mid 3^n-1$ ?   I have tried many things, but nothing worked. let's say that I have a following file structure:  ~/DIR1 -fileA -DIR2 --fileB   Then, being in ~, I run this script:  cp DIR1 NEWDIR2   And just an error happens:  cp: omitting directory ‘DIR1’   I understand why nothing from DIR1 gets copied (because I didn't use -r switch that would enforce recursion) but I'd expect the DIR1 folder itself copied to NEWDIR2 (so practically a creation of a new "NEWDIR2" in ~ or a creation of ~/NEWDIR2/DIR1).  Could someone explain to me why is my expectation wrong? Check if element found in array c++ How do I remove all specific characters at the end of a string in PHP? database disk image is malformed with dnf on Fedora 29 bash is not terminating I'm trying some things with my shell. This includes the following command:  kill $$  My expectation was that the shell would log me out and terminate itself. But instead the bash persists without change.   Any idea why?  I ran this command on different environments (archlinux, debian). The behavior was always the same. How can I take browser screenshots at a higher resolution than my browser supports? From a paper via Schneier on Security's  (emphasis mine):  In the case of AES-128, there is no known attack which is faster than the 2128 complexity of exhaustive search. However, AES-192 and AES-256 were recently shown to be breakable by attacks which require 2176 and 2119 time, respectively. While these complexities are much faster than exhaustive search, they are completely non-practical, and do not seem to pose any real threat to the security of AES-based systems. In this paper we describe several attacks which can break with practical complexity variants of AES-256 whose number of rounds are comparable to that of AES-128.  Is the implication here that AES-192 is stronger than AES-256? If so, in simple terms, how is that possible?  The attack exploits the fact that the key schedule for 256-bit version is pretty lousy -- something we pointed out in our 2000 paper -- but doesn't extend to AES with a 128-bit key.  Again, in simple terms, what does that mean? In practice, does this mean I should drop AES-256 in favor of its 128-bit counterpart, like Schneier recommends in the comments?  That being said, the key schedule for AES-256 is very poor. I would recommend that people use AES-128 and not AES-256. How to use Font as a variable? How to delete file(s) in secure manner? I need to knock out a quick animation in C#/Windows Forms for a Halloween display.  Just some 2D shapes moving about on a solid background.  Since this is just a quick one-off project I really don't want to install and learn an entire new set of tools for this.  (DirectX dev kits, Silverlight, Flash, etc..)  I also have to install this on multiple computers so anything beyond the basic .Net framework (2.0) would be a pain in the arse.  For tools I've got VS2k8, 25 years of development experience, a wheelbarrow, holocaust cloak, and about 2 days to knock this out.  I haven't done animation since using assembler on my Atari 130XE (hooray for page flipping and player/missile graphics!)  Advice?  Here's some of the things I'd like to know:   I can draw on any empty widget (like a panel) by fiddling with it's OnPaint handler, right?  That's how I'd draw a custom widget.  Is there a better technique than this? Is there a page-flipping technique for this kind of thing in Windows Forms?  I'm not looking for a high frame rate, just as little flicker/drawing as necessary.   Thanks.  Post Mortem Edit ... "a couple of coding days later"  Well, the project is done.  The links below came in handy although a couple of them were 404.  (I wish SO would allow more than one reply to be marked "correct").  The biggest problem I had to overcome was flickering, and a persistent bug when I tried to draw on the form directly.   Using the OnPaint event for the Form: bad idea.  I never got that to work; lots of mysterious errors (stack overflows, or ArgumentNullExceptions).  I wound up using a panel sized to fill the form and that worked fine. Using the OnPaint method is slow anyway.  Somewhere online I read that building the PaintEventArgs was slow, and they weren't kidding.  Lots of flickering went away when I abandoned this.  Skip the OnPaint/Invalidate() and just paint it yourself.  Setting all of the "double buffering" options on the form still left some flicker that had to be fixed.  (And I found conflicting docs that said "set them on the control" and "set them on the form".  Well controls don't have a .SetStyle() method.)  I haven't tested without them, so they might be doing something (this is the form):      this.SetStyle(ControlStyles.UserPaint, true);     this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);     this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);    So the workhorse of the code wound up looking like (pf is the panel control):      void PaintPlayField()     {         Bitmap bufl = new Bitmap(pf.Width, pf.Height);         using (Graphics g = Graphics.FromImage(bufl))         {             g.FillRectangle(Brushes.Black, new Rectangle(0, 0, pf.Width, pf.Height));             DrawItems(g);             DrawMoreItems(g);             pf.CreateGraphics().DrawImageUnscaled(bufl, 0, 0);         }     }   And I just called PaintPlayField from the inside of my Timer loop.  No flicker at all. Partial Fraction Decomposition? I am trying to solve the following question which is Ex3 from Arthur Engel, Problem Solving strategies. Here is the question: $\sum_{k=1}^n k^3 {n \choose k}$ and asks to find the sum. I am sincerely having a hard time trying to figure out how to solve it and get $n^2 (n+3)(2)^{n-3}$. I would really appreciate if someone could show the step-by-step process. Thank you! Find two elements that don't have a gcd in a subring of Gaussian integers 16.04 Upgrade: Failed to fetch Empty files can't be valid archives Can't append  element Any idea why the piece of code below does not add the script element to the DOM?  var code = "&lt;script&gt;&lt;/script&gt;"; $("#someElement").append(code); "Taste" is to "flavor" as "touch" and "sight" are to what? For the senses, we have:    flavor for taste aroma/odor/scent for smell sound for hearing ____? for touch/feel ____? for sight/see   So one tastes a flavor, smells an aroma, hears a sound, feels a(n) _____, and sees a(n) _____. For the former, part of me wants to say texture, but I feel that is too specific; for the latter, I want to use visual or sight, but but does that make sense, seeing a visual or a sight? I have a sqlite (v3) table with this column definition:  "timestamp" DATETIME DEFAULT CURRENT_TIMESTAMP   The server that this database lives on is in the CST time zone.  When I insert into my table without including the timestamp column, sqlite automatically populates that field with the current timestamp in GMT, not CST.  Is there a way to modify my insert statement to force the stored timestamp to be in CST?  On the other hand, it is probably better to store it in GMT (in case the database gets moved to a different timezone, for example), so is there a way I can modify my select SQL to convert the stored timestamp to CST when I extract it from the table? Formula label outside of formula Does $\sum \limits_{n=1}^\infty\frac{\sin n}{n}(1+\frac{1}{2}+\cdots+\frac{1}{n})$ converge (absolutely)? I've had no luck with this one. None of the convergence tests pop into mind.  I tried looking at it in this form $\sum \sin n\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}$ and apply Dirichlets test. I know that $\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n} \to 0$ but not sure if it's decreasing.  Regarding absolute convergence, I tried:  $$|\sin n\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}|\geq \sin^2 n\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}=$$  $$=\frac{1}{2}\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}-\frac{1}{2}\cos 2n\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}$$  But again I'm stuck with $\cos 2n\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}$. Assuming it converges then I've shown that $\sum \sin n\frac{1+\frac{1}{2}+\cdots+\frac{1}{n}}{n}$ doesn't converge absolutely.