Must the int main() function return a value in all compilers?
What should main() return in C and C++?
I noticed that, for each research project, there comes a point where I have to consult the literature, and find all the previous research related to the current project.  Unfortunately, I seem to be very inefficient in my approach. I spend a lot of time digging through papers that are really interesting, but only of tangential importance to my current work, just to find the few papers that actually do similar things. (The pile of "cool paper, read when time" just keeps growing.)  Hence, I'm wondering: What is the most time efficient way to get a thorough overview of the literature in a specific niche of a field?    While searching for an answer I came across these questions:   - This question is quite similar and I liked the approach. I debated with myself if this is a duplicate, but I think it is focused more on how to be sure the search was exhaustive, whereas I'm worried about time efficiency. (Also, I'm a bit curious if things have changed since 2012.)   - The answer provides tips on how to identify what literature generally is important in a field, but I am looking for the most cost effective (least time consuming) way to do it in an area, where I know the broad literature, but not the specifics. In the , if I select any site in the site switcher it will be set as Stack Overflow or some random site in the drop down list's selected site name.  For the Stack Overflow, Super User, Server Fault and Meta Stack Exchange, the site switcher is set to the selected site name, but the remaining do not retain the selected site name. For English Language and Usage, it changes to Physical Fitness for some reason. All the others I've tried  switch to Stack Overflow.  It can be replicated in Chrome and Firefox.  GIF for the same: Show that if $\sup\big\{\sum\lvert\, f(a)\rvert\big\}  0\}$ is countable. Let $f:A \to \mathbb R$ and suppose that $$ \sup\Big\{\sum_{a\in F}\lvert\, f(a)\rvert :  F\text{ is finite subset of }A\Big\} &lt; \infty $$ then the set $\{ a \in A : f(a) &gt; 0\}$ is countable.  My try: Define these element of ${ a ∈ A : f(a) &gt; 0}$, then $∑_{n=1}^\infty\lvert\, f(a_n)\rvert$ is determined, regardless of the method of arrangement. I'm arriving to the US by air, but departing via land. How do I end form I-94 now that it is only electronic? Let me filter jobs by the employer's Joel Test Scores A recent downvote drew my attention to my  four years ago to . I edited the answer to update the links and to (very slightly) change the tone of the answer. I was in a very bad mood at the time of the answer.  Still, reading the comments, I think I was largely correct: it's better for the site if we encourage people to do a little research before posting. Maybe even just the "two minutes of searching" that I refer to in the answer.  I was considering deleting the answer, but decided to bring the old debate back to Meta, instead.  "Was I right, or was I right?" One of the boys who always give/gives the correct answer is Samuel.   As per rule, one of is followed by plural noun/pronoun and singular helping verb, so we should be using gives in the sentence. But the answer is give. You have 6 red balls, 6 blue, and 6 white. You randomly select a sample of 3 balls without replacement. The balls, save for the color, are indistinguishable from each other. What are the odds that your sample contains at least a ball from each color?  I thought about finding the chance that the sample will not contain at least one color and subtracting that from one:  $$P(\text{sample is missing at least one color})=P(\text{sample is missing one color})+P(\text{sample is missing two colors}) $$  Essentially the second probability statement on the right hand side is the probability that all the balls in the sample are the same color. The case where the sample does not contain three colors doesn't make sense, so I didn't include it. $$=\binom{3}{1} \left[\left(\frac{12}{18}\right) \cdot \left(\frac{11}{17}\right) \cdot\left(\frac{10}{16}\right)\right]+\binom{3}{2}\left[\left(\frac{6}{18}\right) \cdot \left(\frac{5}{17}\right) \cdot\left(\frac{4}{16}\right)\right] \approx 0.882353$$  When all of this is done, we simply subtract the probability from one to get $0.117647$.  What am I doing wrong? Suppose I'm given the mean and one quantile (e.g. the 20% quantile) of a random variable $x$, and I want to find the parameters $\alpha$ and $\beta$ of a Beta distribution that has the same mean and quantile.  Is there an efficient way to do it?    Using just the mean, I know that since $\bar{x} = \frac{\alpha}{\alpha+\beta}$, we have $\beta = \frac{\alpha}{\bar{x}} - \alpha$.  So we only really have one parameter to estimate.  But I'm unsure how to use the quantile information to take the next step.  Maybe there's something I can do with the Incomplete Beta when I know the ratio $\frac{\beta}{\alpha} = \frac{1-\bar{x}}{\bar{x}}$?  I have access to R myself, so I could use a numerical optimizer for this, but ideally I need a method that can be carried out in Excel in someone else's environment.  Excel does have BETA.DIST() and BETA.INV() functions available.  A look-up table would be fine, but a closed-form formula would be better if it's possible. Why a tesselation of the plane by a convex polygon of 7 or more sides is not possible? I read in several places, including Wikipedia, that a tessellation of the plane by a single, convex, $n-$sided polygon is not possible for $n\geq7$. I was not able to locate a proof, or a paper that discusses this. Maybe it is too trivial, but I am not able to figure it out myself.   So I would like to ask you for help. Where can I find a proof for this?  Also, I am interested in the mathematical background behind plane tiling (especially periodic), If you can suggest papers on the topic it would really help. Why does sizeof(x++) not increment x? Prove that a product of two complex numbers has zero imaginary part This is my homework, which reads as follows: Let $z_1, z_2$ be complex numbers.  Prove that when $z_1z_2 \neq -1$ and $|z_1| = |z_2| = 1$, then the imaginary part of $$ \frac{z_1 + z_2}{1 + z_1z_2} $$ is zero.  I've tried to approach this in several ways, but whichever one I try, at some point the expression gets too large and doesn't simplify (at least I cannot find a way to simplify it).  The way I tried to approach this problem is to:   Set $z_1 = a+bi$, $z_2 = c+di$, then $z_1+z_2=(a+c)+(b+d)i$, and in polar form, $\sqrt{(a + c)^2 + (b + d)^2}\times (\cos\theta + i\sin\theta)$, $\tan \theta = \frac{b+d}{a+c}$. Find $\tan \phi$, where $\phi$ is the angle of $\frac{1}{1 + z_1z_2}$. Substitute into $\tan(\theta + \phi) = \frac{\tan(\theta)+\tan(\phi)}{1-\tan(\theta)\tan(\phi)} = 0$.   The problem is $\tan(\phi)$ is a huge expression, and I cannot get it to simplify, so I cannot also show that the last formula is actually true.  Since this is a homework, and we are expected to do this with pan and paper (not even a calculator...), I don't believe we are to do this many calculations by hand.  Hence, there must be some "trick" to get this to simplify, or a completely different approach.  Would you care to give me a hint? Difference between "per" and "a" Prove that if $b = dk$ where $gcd(m, a) = d$, there are $d$ solutions to $ax \equiv b \mod m$ I know that there exists at least one solution, because $ax \equiv b \mod m \implies ax - b = qm$  Rearranging terms gives $ax - qm = b$, and since $d | a$ and $d | m$, so $d | b$ it can be said that $b \equiv 0 \mod d$.  I implemented Euclid's extended algorithm and have been able to experimentally verify that the claim holds, but I do not see a pattern or how I can begin to show there are exactly $d$ solutions.  def euclid_extended(x, y, i=0):   if y == 0:     print("iteration {0} returns ({1}, {2}, {3}) - base case hit with ({4}, {5})".format(i, x, 1, 0, x, y))     return (x, 1, 0)   else:     (d, a, b) = euclid_extended(y, x % y, i + 1)     print("iteration {0}. ({4}, {5}) =&gt; ({1}, {2}, {3})".format(i, d, b, a - b * (x//y), x, y))     return (d, b, a - b * (x//y)) Is it possible to take screenshots on the 3DS? In Pokemon X and Y there are specific locations in the game that allows you to save what are essentially 3D screenshots from the upper screen using a virtual camera. This made me wonder - is it possible to take screenshots, 3D or otherwise, from within the 3DS? How To Delete This Red Box on My Screen? I was editing my mesh and I wanted to only see a part of my mesh, so I pressed alt+B to only show a selected area. However, I did ctrl+B and created a red rectangle on my screen (I don't know what it does). Does anybody know how to get it off? How to mathematically evaluate a string like "2-1" to produce "1"? Why is it that when you add normally distributed random variables the variance gets larger but in the Central Limit Theorem it gets smaller? When you add two independent normal distributions the resulting distributions' variance is the sum of the variances i.e. it gets larger.  However, the Central Limit Theorem states that  when independent random variables are added, their properly normalized sum tends toward a normal distribution (informally a bell curve) even if the original variables themselves are not normally distributed.   and also says that as you add more variables the variance gets smaller. Why does the variance increase in one case but decrease in the other? Is it because in the CLT case the random variables come from the same underlying distribution? How to show $\lim_{n \to \infty} a_n = \frac{ [x] + [2x] + [3x] + \dotsb + [nx] }{n^2} = x/2$? This question came from the prelim exam I took last month. I have a proof that seems a bit unwieldy to me (posted as an answer), so I'm opening it up to ask if there are other ways of showing this.     Let $x$ be any positive real number, and define a sequence $\{a_n\}$ by   $$ a_n = \frac{ [x] + [2x] + [3x] + \dotsb + [nx] }{n^2} $$   where $[x]$ is the largest integer less than or equal to $x$. Prove that $\displaystyle{\lim_{n \to \infty} a_n = x/2}$. Time limited and band limited signal