There is some "type of commutativity" between specifiers, as in:  int const arr[5] = { /*initial (and only) values*/}; const int arr[5] = { /* -//-*/};   where regardless of the sequence of the type name int and const specifier in the definition, the interpretation is the same: an array of const ints. Similarly, when accessing an predefined array element:  int a = arr[4]; int a = 4[arr];   there is equivalence between both ways of access.  Are there any other frequently used* similar cases?  *highly used expressions that exhibit similar behaviour and could be possibly misunderstood
As Joel points out in , in  (aka: K &amp; R), there is mention of this property of arrays in C: a[5] == 5[a]  Joel says that it's because of pointer arithmetic but I still don't understand. Why does a[5] == 5[a]?
Is there a C pre-processor which eliminates #ifdef blocks based on values defined/undefined? Showing a tensor is not a simple tensor Let $(e_1,e_2)$ be the standard basis of $\mathbb{R}^2$. Why can the element $e_1\otimes e_2 + e_2\otimes e_1$ in $ \mathbb{R}^2\otimes_{\mathbb{R}} \mathbb{R}^2 $ not be written as a simple tensor $v\otimes w$ for $v,w\in \mathbb{R}^2$?  If we suppose $e_1\otimes e_2 + e_2\otimes e_1=v\otimes w$, then can we conclude that $e_1=\lambda e_2$ for some $\lambda \in \mathbb{R}$? This would give a contradiction since $e_1$ and $e_2$ are linearly independent. However, I am not sure if the argument is valid. I am having some issues when rendering an image, my rendering screen is turning into grey even when making a full render. What am I doing wrong? How would I identify what's causing my Mac to permanently hang on shutdown? Whenever I try to shutdown or reboot my Mac (Macbook Pro 15" Retina late 2013, OS X 10.11.3) it closes all programs like normal and then it goes into that black screen with the progress bar. When it gets to about halfway it permanently hangs and won't ever finish rebooting. I looked at the log viewer and couldn't find anything in particular. Is there a way to monitor a shutdown more closely and find out what's causing it to get stuck? Paging using ldapsearch I am searching an LDAP directory that has a much larger number of results than the sizelimit currently set,500, by slapd.conf that for all intents and purposes cannot be changed)  My idea was to keep running ldapsearch but from a different offset each time (501, 1001, etc.) until all results have been obtained.  I have seen the , and it appears that this is handled for you using the -E options:  -E [!]&lt;ext&gt;[=&lt;extparam&gt;] search extensions (! indicates criticality)          [!]domainScope              (domain scope)          [!]mv=&lt;filter&gt;              (matched values filter)          [!]pr=&lt;size&gt;[/prompt|noprompt]   (paged results/prompt)          [!]subentries[=true|false]  (subentries)          [!]sync=ro[/&lt;cookie&gt;]            (LDAP Sync refreshOnly)                  rp[/&lt;cookie&gt;][/&lt;slimit&gt;] (LDAP Sync refreshAndPersist)   So i tried: ldapsearch -h $HOST -p $PORT -x -L -b "$BASE" '*' '+' -E pr=$SIZE  However when the results (even paged results with size = 50 for example) hit 500, I get the same error as if the results were not paged:  Size limit exceeded (4)  I have seen in the man pages there is another option for virtuallistview but have been unable to find examples for it, and as well I dont think my version of ldapsearch has this option.  The goal here is to create a backup using ldapsearch and the -L option to create an ldif file that is suitable for restoring the database.  A few google searches show up with the same problem I'm having, but none have an applicable solution.. $(a_n+a_{n+1})$ is convergent implies $(a_n/n)$ converges to $0$ Let $(a_n)$ be a sequence such that $(a_n+a_{n+1})$ is convergent. Prove that $(a_n/n)$ converges to $0$.   $(a_n+a_{n+1})$ convergent to $L$ means that for all $\epsilon$, there exists $N$ such that for all $n\geq N$, $|L-a_n-a_{n+1}|&lt;\epsilon$, or in other words $L-\epsilon&lt;a_n+a_{n+1}&lt;L+\epsilon$. How to proceed from here? Linear Discriminant Analysis for $p=1$ Cannot change stroke width in Inkscape I am trying to change the stroke width of an icon in Inkscape but, unlike other times I have done this, this time the stroke width appears to be 0 px and I am not allowed to make it thinner:    The stroke width is actually quite large already, is there another setting I should edit to make it thinner?  You can download the file I am working on .  BTW: sorry for the potato quality of the screenshot, this is what you get using Inkscape on a retina screen :/ You see him for a split second in the final scene with the Final Order and he has kind of a white beard. I can't find any reference online except Nien Nunb from ROJ. Add an API key to QGIS for QOSM layer I'm assuming that the answer to the question in the title is a resounding yes. Since Baryonic matter and dark matter interact via gravitational forces.  If this is the case how is information not lost if, as is presumed, dark matter does not interact via the electromagnetic force? What can I do when getting “This question body does not meet our quality standards”? While trying to ask a question, I got the error message     This question body does not meet our quality standards. Please make sure that it completely describes your problem - including what you have already tried - and is written using proper grammar.    Why am I getting this message? What can I do to get the system to accept my question? Can you be more specific? What are good resources on how to ask high-quality questions?      For more information, see  in the . Pay real money to set bounties (another method, not replacing rep method) It may seem like a stupid thing, but could we please be able to pay real money to set a bounty.  For example, if I had only 1 rep, I want to be able have a bounty.   Here late the suggested prices in USD. Convert money    $0.49 for each 50 reputation $0.99 for each week $1.99 for a month $9.99 for a year   Every month, the bounty fee would come in. This would mean you would have to enable your account with a bounty fee button on your profile. What is the resolution of tapping a blocking creature? Tikz: setting options for pin I just found the pin option to drawing, and it looks useful in some of the things I want to draw. How do I format it though? I've tried pin=[red]60:{Hey!} and I get the error Cannot parse this coordinate.  \documentclass{standalone} \usepackage{tikz} \usetikzlibrary{shapes,arrows,positioning} \begin{document} \begin{tikzpicture}[node distance=2cm,&gt;=latex, every node/.style={     font=\sffamily\scriptsize     },       circtext/.style={draw,circle,minimum size=8pt,inner sep=2pt},     dot/.style={draw,circle,fill=black,minimum size=0.6mm,inner sep=0pt} ] { \node[rectangle, fill=green!10!white!90!black, minimum width=6cm, minimum height=3cm] at (2,0){}; \node[circtext, fill=yellow](A) at (0,0) {A}; \node[circtext, fill=yellow, right=of A](B){B}; \draw[-&gt;] (A) -- node[dot, pos=0.5, pin=[red]60:{Hey!}](C){}(B); } \end{tikzpicture} \end{document}     The default style looks like it's a gray thin arrow, and I want to change it to a black thin dotted line with no arrow.    update: I figured out how to add style to the pin node:  pin={[red]60:Hey!}]  But I can't figure out how to change the linestyle though. How to change all the keys of a hash by a new set of given keys Invariance, covariance and symmetry Though often heard, often read, often felt being overused, I wonder what are the precise definitions of invariance and covariance. Could you please give me an example from field theory? In non-relativistic QM, the $\Delta E$ in the time-energy uncertainty principle is the limiting standard deviation of the set of energy measurements of $n$ identically prepared systems as $n$ goes to infinity. What does the $\Delta t$ mean, since $t$ is not even an observable? inequality with three variables and condition Unknown apps/processes with number only are shown in data usage A mysterious app named &quot;10102&quot; shows up in my data usage. It bears only the standard Android app icon (the Bugdroid logo with a cube on its torso). From what the graph tells me, it has used 36 megabytes of data in the background and zero on the foreground. I think I haven't uninstalled anything for months. Is it malware? I haven't sideloaded anything and only authorized my laptop as a USB debugger. If it's malware, how do I remove it? I have no idea how to find its package name and 10102 isn't in the list of downloaded apps in settings. I'm running stock &amp; never-been-rooted Android 4.4.4 on Nexus 4.