Why do I need the static keyword here?
What is the reason behind "non-static method cannot be referenced from a static context"?
Using package nomencl Difference between wouldn't and didn't What is the difference between would not and did not?  For example:     I called my girlfriend but she wouldn't stop.   I called my girlfriend but she didn't stop. What is the difference between # and . when declaring a set of styles for an element and what are the semantics that come into play when deciding which one to use? I ajaxly call a route and pass data to it, In my controller, I want to get $_POST['var'] , $_POST['var2'], it seems because of using HttpFoundation in drupal 8, $_POST and $_GET are not exists in old method, How I can access $_POST parameters in custom Controller? Rational solutions of $y^2 = x^3 - x$ Related:  (not a dupe, that's a feature request and was closed as a dupe of another one)        (old) post does indeed say that Link-only answers can be flagged as NAA, but there are a lot of posts like  which define Not An Answer is a way that it doesn't apply to link-only answers.  Can we get some up-to-date consensus on this? That link only answers are not allowed is . How to Search for Files Recursively into Subdirectories I am trying to look for all XML files in a particular directory and all sub-directories (recursively) inside it.  ls -R *.xml is only listing files in the current directory. I am quite sure, the sub-folders themselves have several .xml files, but none are showing up.  Is this a configuration issue? What is the difference between a population and a sample? What is the difference between a population and a sample? What common variables and statistics are used for each one, and how do those relate to each other? How do constant aperture zoom lenses work? Cheaper zoom lenses usually are faster at the wide end and slower at the long end (for example, the $150 Canon EF-S 18-55mm f/3.5-5.6). More expensive constant-aperture zoom lenses have the same aperture regardless (for example, $800 Canon EF 17-40mm f/4.0 L).  My question is: are these good lenses  at the wider settings, or do they have a different optic system that allows them to maintain the same aperture throughout the zoom range? As I understand it, there are several models for what the universe could look like from the “outside”. I don’t know if any of these are outdated, so if they are please tell me if they are.   Expanding bubble. This model says the universe will never stop expanding, and the universe will die because the energy all turns to photons and gets spread out so much. Bubble that will eventually collapse. In this model the universe will stop expanding, and collapse. Everything merges into super-massive black holes, and the universe dies with fire. The universe is a torus. I'm not clear whether the size of the universe in this model is changing, but the central idea is that space is donut-shaped.   Those are the major ones that I have heard of. My question involves what I have heard to be the most popular of the three, #2. In this model, eventually something will "touch" the edge of the universe. Obviously, the first thing to "touch" it would be photons as they travel at, well, the speed of light. This involves all forms of energy in the universe, but I thought it might be easier to explain for something without mass.  What happens if some form of energy "touches" the edge of the universe? Logically, the energy cannot be lost without violating the law of conservation of energy. The only thing I can think of, is that it would "bounce" or be refracted off the edge.  I realize that it sounds silly, however if model #2 is correct then this situation will arise some number of billions of years from now.  I can only assume that there is either a new model that accounts for this, there is some complex explanation, or that model #2 is incorrect. Ramanujan log-trigonometric integrals I discovered the following conjectured identity numerically while studying a family of related integrals.  Let's set $$ R^{+}:=  \frac{2}{\pi}\int_{0}^{\pi/2}\sqrt[\normalsize{8}]{x^2 + \ln^2\!\cos x} \sqrt{ \frac{1}{2}+\frac{1}{2}\sqrt{ \frac{1}{2}+ \frac{1}{2}  \sqrt{ \frac{\ln^{2}\!\cos x}{ x^2 + \ln^2\! \cos x}}}}\,\mathrm{d}x, \tag1 $$ $$ R^{-}:=  \frac{2}{\pi}\int_{0}^{\pi/2}\frac{1}{\sqrt[\normalsize{8}]{x^2 + \ln^2\!\cos x}} \sqrt{ \frac{1}{2}+\frac{1}{2}\sqrt{ \frac{1}{2}+ \frac{1}{2} \sqrt{ \frac{\ln^{2}\!\cos x}{ x^2 + \ln^2\! \cos x}}}}\,\mathrm{d}x. \tag2 $$ We may numerically observe with at least 500 digits of precision that $$  \begin{align} &amp; R^{+}R^{-} \stackrel{?}{=}1 \tag 3 \\\\ &amp; R^{+} \stackrel{?}{=} \sqrt[\normalsize{4}]{\ln 2} \tag4 \\\\ &amp; R^{-} \stackrel{?}{=}\frac{1}{\sqrt[\normalsize{4}]{\ln 2}}. \tag5 \end{align} $$  How can we prove it?  A version of this has been sent to Eric Weisstein, these integrals are on Mathworld as . MacBook Pro Trackpad Suddenly Stopped Working Completely The trackpad on my Macbook Pro of 2 years has suddenly stopped working out of blue.  The trackpad doesn't move, respond to any gestures nor do any clicks work. This is really frustrating as I used gestures a lot to navigate around my laptop, and even though I use a bluetooth mouse it makes using my laptop unnecessarily laborious.  Does anyone know what may be causing the problem, and any solutions? Converting a pointer into an integer I am trying to adapt an existing code to a 64 bit machine. The main problem is that in one function, the previous coder uses a void* argument that is converted into suitable type in the function itself. A short example:  void function(MESSAGE_ID id, void* param) {     if(id == FOO) {         int real_param = (int)param;         // ...     } }   Of course, on a 64 bit machine, I get the error:  error: cast from 'void*' to 'int' loses precision   I would like to correct this so that it still works on a 32 bit machine and as cleanly as possible. Any idea ? I have a table story_category in my database with corrupt entries. The next query returns the corrupt entries:  SELECT *  FROM  story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category INNER JOIN         story_category ON category_id=category.id);   I tried to delete them executing:  DELETE FROM story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category        INNER JOIN story_category ON category_id=category.id);   But I get the next error:      #1093 - You can't specify target table 'story_category' for update in FROM clause    How can I overcome this? Biblatex: submitting to a journal Is there a difference between "Alpha Helix" and "Alpha subunit"? Why is there so much fear surrounding LiPo batteries? I've been trying to design a charging system for a small robot powered by a 2S 20C  (LiPo) battery. Were I to trust everything I read online, I would believe that the LiPo will kill me in my sleep and steal my life savings. The common advice I read, if you are brave enough to use LiPo batteries, is "never leave unattended", "never charge on top of a flammable or conductive surface", and "never charge at a rate faster than 1&nbsp;".  I understand why this is prudent, but what is the actual risk with LiPo batteries?  Nearly every cell phone, both Android and iPhone alike, contains a LiPo battery, which most people, including myself, charge while unattended&mdash;often-times while left on a flammable or conductive surface. Yet you never hear about someone bursting into flames because their cell phone exploded. Yes, I know there are freak accidents, but how dangerous are modern LiPo batteries? Why do so many online commenters treat stand-alone LiPo batteries like bombs waiting to go off, but don't even think twice about the LiPo sitting in their pocket? What will happen to my reputation when the Community Wiki status of a post is reversed? Why getting this error tlmgr Unknown directive? I haven't used tlmgr for a while but when I tried to install any package with it today, It returned following message:     (running on Debian, switching to user mode!) Unknown directive ...containerchecksum c59200574a316416a23695c258edf3a32531fbda43ccdc09360ee105c3f07f9fb77df17c4ba4c2ea4f3a5ea6667e064b51e3d8c2fe6c984ba3e71b4e32716955... , please fix it! at /usr/share/texlive/tlpkg/TeXLive/TLPOBJ.pm line 210,  line 5579.   I've tried to use fix specified on :     You have to download update-tlmgr-latest.sh from the tlpretest repository   and run it. Afterwards you will be able to work with tlmgr as usual   (announced by Norbert a few hours ago).   I've downloaded it from , but it returned another error:  Verifying archive integrity... All good. Uncompressing TeX Live Manager Updater............................................................................................................................................................................ ./runme.sh: Cannot find TeX Live root using kpsewhich --var-value=SELFAUTOPARENT. ./runme.sh: Please set your PATH as needed, otherwise it's hopeless.   Minimum example  Install cleanly vanilla TeXLive 2016 with tmlgr after having old TeXLive in the system successfully: there is no errors/warnings in /usr/local/texlive/2016/*.log, complete log example . Run the following but you get the same output as above when trying to update the system  root@masi:/home/masi/Downloads/t/install-tl-20161019# tlmgr update --self (running on Debian, switching to user mode!) Unknown directive ...containerchecksum c59200574a316416a23695c258edf3a32531fbda43ccdc09360ee105c3f07f9fb77df17c4ba4c2ea4f3a5ea6667e064b51e3d8c2fe6c984ba3e71b4e32716955... , please fix it! at /usr/share/texlive/tlpkg/TeXLive/TLPOBJ.pm line 210, &lt;$retfh&gt; line 5579. Is it possible to recover an email that has been clicked "delete forever" in the trash folder? Is it possible to recover an email that has been clicked on "delete forever" in the trash folder? I have accidentally clicked delete forever for an email but now I need to recover it.