With the Objective-C/Swift Singleton model, why do we create a shared instance and not just use class methods?
Objective-C: Use singleton vs. use class as an object?
Six simple tips to get Stack Overflow reputation fast From "6 Simple Tips to Get Stackoverflow Reputation Fast" at codexon.com:   Be the First to Answer. Even at the cost of quality. Use Downvotes and Comments Strategically Use obnoxious in-your-face formatting and lists. Be Aware of the 200 rep/day Limit Edit, But Don’t Edit Too Much Associate your other accounts   Courtesy of . Agree? Disagree? Walnuts? Cantaloupe? Allow applications downloaded from anywhere in macOS Sierra In previous versions of the OS in the security pane, you are provided an option of:    But in this version there is no option anywhere:    Is there a way that I can turn on anywhere? (via Terminal maybe?) Are real guns used in movies? Is it possible and furthermore constructive to make LaTeX automatically format specific words in specific way? Let's say, for example, I'd like to have every occurrence of the word "hello" in a bold cyan monospaced font, whereas the rest of the document remains normal, sans serif and black.   How can I achieve that without having to do a search&amp;replace to place "hello" into a custom command every time before I compile the .tex file? There are two Java Web Start tags:  : x 239 : x 320   Both tags refer to the same technology  refers to  both wiki point to  all questions tagged with  clearly relate to Java Web Start   I suggest they be merged into  (which appears in the auto-complete list if one types "webstart" in the Tags box when asking a new question). I have an equation, such as:  \documentclass{report}  \begin{document}  \chapter{hello} \begin{equation} x=1 \end{equation}  \end{document}   And the equation appears as "x=1 (1.1)".    What I want is "x=1 (1)" ignoring the chapter number.  How do I get that?  Thank you. Does scikit-learn have forward selection/stepwise regression algorithm? I'm working on the problem with too many features and training my models takes way too long. I implemented forward selection algorithm to choose features.  However, I was wondering does scikit-learn have forward selection/stepwise regression algorithm? If $2^n+1$ is prime, why must $n$ be a power of $2$? A little bird told me that if $2^n+1$ is prime, then $n$ is a power of $2$. I tend not to trust talking birds, so I'm trying to verify that statement independently.  Suppose $n$ is not a power of $2$. Then $n = a \cdot 2^m$ for some $a$ not a power of $2$ and some integer $m$. This gives $2^n+1 = 2^{a \cdot 2^m}+1$. Now I suspect there's a way to factor that, but I don't see how. Can someone give me a hint? It's stated that the gradient of:  $$\frac{1}{2}x^TAx - b^Tx +c$$  is   $$\frac{1}{2}A^Tx + \frac{1}{2}Ax - b$$  How do you grind out this equation? Or specifically, how do you get from $x^TAx$ to $A^Tx + Ax$? Placement of the asterisk in pointer declarations I've recently decided that I just have to finally learn C/C++, and there is one thing I do not really understand about pointers or more precisely, their definition.  How about these examples:   int* test; int *test; int * test; int* test,test2; int *test,test2; int * test,test2;   Now, to my understanding, the first three cases are all doing the same: Test is not an int, but a pointer to one.  The second set of examples is a bit more tricky. In case 4, both test and test2 will be pointers to an int, whereas in case 5, only test is a pointer, whereas test2 is a "real" int. What about case 6? Same as case 5? Proving a Lipschitz function is continuous A function $f:D\subset \mathbb R \to \mathbb R$  is lipschitz given that there exists a $L\gt0$ such that $|f(x)-f(y)|\le L|x-y|$  I need to prove this function is then continuous. Is there a best definition of continuous functions to use for this proof given the definition of Lipschitz?  Is the epsilon delta way the only way to do it? can someone help me set it up? I really struggle with implementing that definition. Wikipedia entry on likelihood seems ambiguous Difference between Sort and SortBy Putting a piece of code in between two html tags in Solaris What happens if my order exceeds the bid or ask sizes? What will happen if my order exceeds the bid or ask size? For example, if the bid or ask is 100 shares, but I want to buy 100,000 shares, is it possible to do so? Seriously, I had not noticed e.g. Jeff's edit  had he not also retagged my question. Please select a file error How do I use the Chinese remainder theorem to find all the square roots of 11 in $\mathbb Z_{35}$? Should a math paper use non-alphabetical ordering of authors' names for unequal contributions? Using alphabetical ordering for authors' names is a long established tradition in mathematics. In the situations of extremely unequal contributions, is it reasonable to break from this tradition?  Has there been any examples?  If it is common, what is the threshold for breaking from alphabetical ordering? How would I verify the following double angle identity. $$ \sin(A+B)\sin(A-B)=\sin^2A-\sin^2B $$ So far I have done this. $$ (\sin A\cos B+\cos A\sin B)(\sin A\cos B-\cos A\sin B)  $$But I am not sure how to proceed.