Why do we need the friend keyword in this case? friend bool operator=(const Stack&amp;&lt;E&gt; s, const Stack&amp;&lt;E&gt; q);
I have been reading through the  and was curious about the  declaration. I personally have never used it, however I am interested in exploring the language.   What is a good example of using friend?    Reading the FAQ a bit longer I like the idea of the &lt;&lt; &gt;&gt; operator overloading and adding as a friend of those classes. However I am not sure how this doesn't break encapsulation. When can these exceptions stay within the strictness that is OOP?
the cop (who's) escorting him One of the cops escorts Tim out of the house and toward a police car. Curious neighbors have gathered outside. Tim spits on the cop (who's) escorting him.   Is &quot;escorts&quot; the more natural choice of verb to use in this context?  Is the emboldened sentence phrased naturally without adding &quot;who's&quot;? Can I get back my saved data? Why does $\sum_1^\infty \frac1{n^3}=\frac52\sum_1^\infty\frac{(-1)^{n-1}}{n^3\binom{2n}{n}}$? Apery's original proof that $$ \zeta(3) \equiv \sum_1^\infty \frac1{n^3} $$ is irrational starts from an alternating series  $$ \zeta(3) = \frac52\sum_1^\infty\frac{(-1)^{n-1}}{n^3\binom{2n}{n}} $$  There must be a way to see that those two series are equal, but I have tried various telescoping and other techniques and I just can't see it. Help me out:       Show (preferably by reasonably elementary means) that$$\sum_1^\infty \frac1{n^3}=\frac52\sum_1^\infty\frac{(-1)^{n-1}}{n^3\binom{2n}{n}}$$ I accidentally removed all the packages starting with the name jpeg with:  sudo apt-get remove jpeg*   This screwed up a lot of things, removed Unity, Firefox, Flash player etc.  I somehow managed to recover the desktop and unity but then a lot of things are still buggy. For example .rpm files and .tag.gz just won't open up at all.  What I want is a way to fix everything that's amiss. Something that is the equivalent of a 'repair installation' with a windows disc.  Any tips, anyone? How to install clang++? I'm having trouble getting clang++ to work as I compile my code. Specifically, I'm getting a make: clang++: Command not found error.  I've run sudo apt-get install llvm, and also sudo apt-get install build-essential and sudo apt-get update. What do I have to do to get clang++ installed? Adjectives and nouns to describe an answer that doesn't answer the question? I've heard of the adjectives 'nonresponsive' or , but are they restricted to law^?     Collins Dictionary:  =       not responsive, not reacting to a stimulus   The definition above differs from the definitions of adjectives like 'equivocate,  evade' and nouns like , but these are negative and accusive; I prefer neutral connotation.  ^Only if you wish, please see: ,  by David Berg,  by Thomas A. Mauet. In the Deadpool movie when Wade his mutant cells get activated, his skin changes so he looks like Freddy Krueger (As Weasel referred too). But he obtains healing abilities and his cancer gets cured because of it. He's become an immortal person which can heal any wound super fast.  What I don't understand is, why doesn't his skin heal so he would look like before? I remember that Francis (or Ajax) said that it's a 'side-effect' of mutating, but why wouldn't it heal when he has a healing ability? How to revert to factory settings? Is MacBook Pro warming during gaming normal? I have a 2010 MacBook Pro MC371 (Core i5, GeForce 320M, 4Gb RAM).   When I launch a game either new one (i.e. Starcraft 2) or rather old (Unreal Tournament 2004, bootcamped) my MacBook gets rather warm, even hot in the top left corner, around the place where magsafe charger is plugged in. The temperature is more than 40C. The fact that confuses me is that this warming occures even when I play old games.  Is that OK? Is there a closed formula for this summation? I have the summation  $$\sum\limits_{i=1}^n \frac{1}{i^2}$$  And I don't know how to find a closed formula for it. Any ideas? What can I do if a repository/PPA does not have a Release file? Play YouTube videos with MPMoviePlayerController instead of UIWebView Transfer game license So the problem is that account 1 and account 2 bought a game together, but account 1 isn't used anymore. Can we transfer the game license from account 1 to account 3?   The game was bought on account 1 and account 2 activated account 1 as primary. Apply brace expansion in "reverse order" Setting the hostname: FQDN or short name? I've noticed that the "preferred" method of setting the system hostname is fundamentally different between Red Hat/CentOS and Debian/Ubuntu systems.   and the  say the hostname should be the FQDN:     HOSTNAME=&lt;value&gt;, where &lt;value&gt; should be the Fully Qualified Domain   Name (FQDN), such as hostname.example.com, but can be whatever   hostname is necessary.   The  is slightly more ambiguous:     Setup prompts you to supply a host name for this computer, either as a   fully-qualified domain name (FQDN) in the format hostname.domainname   or as a short host name in the format hostname.    says the hostname should not use the FQDN:     3.5.5. The hostname      The kernel maintains the system hostname. The init script in runlevel   S which is symlinked to "/etc/init.d/hostname.sh" sets the system   hostname at boot time (using the hostname command) to the name stored   in "/etc/hostname". This file should contain only the system hostname,   not a fully qualified domain name.   I haven't seen any specific recommendations from IBM about which to use, but  seems to have a preference.  My questions:   In a heterogeneous environment, is it better to use the vendor recommendation, or choose one and be consistent across all hosts? What software have you encountered which is sensitive to whether the hostname is set to the FQDN or short name? Send Gmail calendar invite from alternate email Log4Net "Could not find schema information" messages Using k-fold cross-validation for time-series model selection Question: I want to be sure of something, is the use of k-fold cross-validation with time series is straightforward, or does one need to pay special attention before using it?   Background: I'm modeling a time series of 6 year (with semi-markov chain), with a data sample every 5 min. To compare several models, I'm using a 6-fold cross-validation by separating the data in 6 year, so my training sets (to calculate the parameters) have a length of 5 years, and the test sets have a length of 1 year. I'm not taking into account the time order, so my different sets are :   fold 1 : training [1 2 3 4 5], test [6] fold 2 : training [1 2 3 4 6], test [5] fold 3 : training [1 2 3 5 6], test [4] fold 4 : training [1 2 4 5 6], test [3] fold 5 : training [1 3 4 5 6], test [2] fold 6 : training [2 3 4 5 6], test [1].   I'm making the hypothesis that each year are independent from each other. How can I verify that? Is there any reference showing the applicability of k-fold cross-validation with time series. When should I begin publishing? What is the point of stacking favorite notifications? I noticed I have more notifications than favorites, which means that the notifications are stacked (in other words, there can be more than 1 notification per question).    Here is my reasoning:   Why do they add up?, I don't know where is the benefit of knowing that some of the questions had multiple changes if we are not able to see which questions had how many changes   Since we don't know what questions had what amount of changes, the amount of notifications is just a meaningless number that don't help us too much. Here are some possible solutions:   Add a max of 1 notification per question Keep the same number, but allow us to see how many new changes there were on every question