Why linker doesn't find my template function declared in class?
Why can templates only be implemented in the header file?
Can I use one Apple ID for Apple Music and another for iTunes & App Store? Let us suppose I want to use a shared Apple ID for logging into iTunes &amp; App Store, in order to share music and app purchases with a friend.  But let us also suppose that, despite this, my friend and I have very different tastes in music, so I don't want to share Apple Music playlists and "like" assertions with my friend. In other words, I don't want Apple Music to think I like the music my friend likes, and vice versa.  Is there a way that my friend and I can share an Apple ID for logging into iTunes &amp; App Store, but use different Apple IDs for Apple Music?  I suspect the answer is no, but I just wanted to ask. Spurious whitespace with algpseudocode and noend I'm currently typesetting some pseudocode and was up to now pretty happy with the algorithmicx package and the algpseudocode command set. However, I would now like to use the noend option to omit end lines. That works, but unfortunately introduces additional whitespace (see lines 6 and 7 in the example below). I fiddled around with negative \vspaces but could not come up with a consistent value that works in all cases.    \documentclass{article} \usepackage[noend]{algpseudocode}  \begin{document}  \begin{algorithmic}[1]   \Function{lsolve}{$L$, $b$}     \State $x \gets b$     \For{$j \gets 0$ to $n - 1$}       \State $x_j \gets x_j / l_{jj}$       \ForAll{$i &gt; j$ where $l_{ij} \neq 0$}         \State $x_i \gets x_i - l_{ij} x_j$       \EndFor     \EndFor     \State \Return $x$   \EndFunction \end{algorithmic}  \end{document}   Is there any way to patch algorithmicx or do I have to finetune the pseudocode on a case by case basis? Why is this true?  $(\exists x)(P(x) \Rightarrow (\forall y) P(y))$ What is difference between: "I have been married with (was married with, married) her for three years." What is the difference between the three sentences below?   I have been married with her for three years. I was married with her for three years. I married her for three years. I'm installing a brand new motion activated security light to an existing box on my garage. After removing the old light, I notice it only has white/black wiring while the new light fixture has of course white/black/green (ground) wires to attach. What do I do if no ground wire is available with the old box? In my question  I asked about the definition and usage of the word "model", for which I was told the following definition:     A formula of propositional logic is true under an interpretation iff   the interpretation assigns the truth value T to that formula. If a   formula is true under an interpretation, then that interpretation is   called a model of that formula.   An interpetation satisfies a formula φ iff it is a model of the formula. Same for a set $\Gamma$ of formulas, if an interpretation satisfies all the formulas in $\Gamma$ then it is a model of $\Gamma$. Then if we say $\Gamma \vDash \varphi$ then $\varphi$ is a semantic consequence of $\Gamma$ / is satisfied in all "models" of $\Gamma$ (true whenever everything in $\Gamma$ is true).  This also matches the definitions for model as seen on the Wiki for  and .  All good so far. But when I get really confused when I see posts like  where they use "models" as a word meaning "satisfies all the axioms in a theory."  From Asaf's answer:     Models are structures, and structures are models. But when we say   "model" we mean that there is a particular theory which holds in the   structure, and when we say "structure" we are mainly interested in an   arbitrary interpretation of the language.   From Metin's answer:     A structure is a set with some interpretable symbols(constants,   relations and functions) within a fixed language. You do not ask for   more from a structure.      However...      A model (of a theory) is a structure which satisfies the axioms of the   theory. It makes more "structural sense"...   And then from one of Asaf's comments:     When I say "a model of 𝖹𝖥𝖢" they also know, immediately, that I am   talking about a model which satisfies all the axioms of 𝖹𝖥𝖢.   So I am unclear on which definition is correct or if this is the same word being used in two different ways or if this is "logical model" versus "semantic model" or something else entirely.  On the one hand we seem to have "model" meaning "any interpretation that satisfies a formula or set of formulas." On the other hand we have "model" meaning "Interpretation that satisfies all the axioms of a theory".  From the Wiki article on  we see also:     For a given theory in model theory, a structure is called a model, if   it satisfies the defining axioms of that theory.   So which is it exactly? Does "model" have a different meaning in propositional logic compared to model theory or first-order logic or set theory etc? Templated check for the existence of a class member function? Is it possible to write a template that changes behavior depending on if a certain member function is defined on a class?  Here's a simple example of what I would want to write:  template&lt;class T&gt; std::string optionalToString(T* obj) {     if (FUNCTION_EXISTS(T-&gt;toString))         return obj-&gt;toString();     else         return "toString not defined"; }   So, if class T has toString() defined, then it uses it; otherwise, it doesn't. The magical part that I don't know how to do is the "FUNCTION_EXISTS" part. Order of the Rubik's cube group Associated to the Rubik's cube is a group as described in this : $G = \langle F, B, U, L, D, R\rangle$. For example, the element $F$ corresponds to rotating the front face clockwise by $90$ degrees.  According to the article the order of the group is: $2^{27} 3^{14} 5^3 7^2 11$.  I have come across several places (for example ) where this order has been found by just counting various ways to arrange edges and such. Is there a nice way to compute the order by appealing to more "group theoretic" tools? Functional equation: $f: \mathbb{R} \rightarrow \mathbb{R}$, $f((x + 1) f(y)) = y (f(x) + 1)$ Calculating the expected values of the min/max of 2 random variables How do you interpret a significant but weak correlation? Is there a term for switching syllables of words? Which Pokemon have the highest CP cap? It's clear that the evolved form of Pokemon have a far higher CP cap (and it looks like minimum too) but it would also seem there is a difference between different Pokemon.   For example I have an Oddish at 184 CP which is at 50% of it's cap, and I also have a Ratata at 185 CP but it is far closer to its cap, around 90%.  Which Pokemon have the highest CP caps? How to prove $b=c$ if $ab=ac$ (cancellation law in groups)? I drew a parallelepiped that is spanned by three vectors, and we know the volume is given by the absolute value of the determinant of the matrix - with the three vectors arranged in rows (or columns, since $detA = detA^T$).  How can I draw the tetrahedron from this parallelepiped to convince myself it is indeed 1/6th of the volume, i.e., 1/6 * |detA|?  Thanks, How can I change the local origin of an object, without changing the object location in the world space.  This is the object located at position (0,0,0) in the world space    This is the same object located at position (0,1,0) in the world space, but with its local origin offset so that the object is in the same place    Is there a way to do this in a single step? How to forbid a specific package to be installed? Filesystem shows /dev/nvme0n1p1 instead of /dev/sda I installed a dual boot of Ubuntu 16.04 (Windows being my other OS) two months ago to try it out. I want to allot more space to it on my hard drive. I was looking up tutorials, and I noticed that my filesystem names don't look anything like those in the tutorials. For example:  df -h   outputs:    How would I allot more space to Ubuntu (in layman's terms)? Characterization convex function. Volume form on $(n-1)$-sphere $S^{n-1}$ Let $\omega$ the (n-1) form on $\mathbb{R}^n$ $$\omega=\sum_{j=1}^{n}(-1)^{j-1}x_{j}dx_{1}\wedge\cdots\wedge \hat{dx_{j}}\wedge\cdots dx_{n}$$ Show that the restriction of $\omega$ to $S^{n-1}$ in precisely the volume for this sphere.  What I did was: $\omega$ never vanish on the sphere, because, defining $\sigma\in \Omega^{n-1}(S)$ for $$\sigma_{p}(v_{1},...,v_{n-1})=det(p,v_{1},...,v_{n-1})$$ and $i:S^{n-1}\rightarrow \mathbb{R}^{n}$ the inclusion function, then $\omega=i^{\ast}(\sigma)$ then $\omega\not=0$ and therfore is a volume form.   How proof that $\omega$ is the volume form?   The first thing that comes to mind is show that $\int_{S^{n-1}}\omega=Vol(S^{n-1})$ but I have serious problems with the definition, I think that is to much.   How see that $\omega$ is invariant on $\mathbb{R}^{n}$ under action of $O(n)$