I understand that 2.675 rounds to 2.67 in python2. I understand WHY it rounds down instead of rounding up.  However, there is no case that I can think of where this is the desired outcome.   So, is there a better way to deal with this than defining my own round function?  def r2(n, d):   return round(n * 10**d) / 10**d   Is there a case where this will fail?  Also, how is this not considered a bug?
Consider the following code:   0.1 + 0.2 == 0.3  -&gt;  false   0.1 + 0.2         -&gt;  0.30000000000000004   Why do these inaccuracies happen?
Find the population size that maximizes the probability that two random samples of size $20$ will have exactly $2$ members in common Ten fish are caught in a lake, marked, and then returned to the lake. Two days later 20 fish are again caught, 2 of which have been marked.  (a) Find the probability of 2 of the 20 fish being marked if the lake has $k$ fish (assuming the fish are caught at random). (b) What value of k maximizes the probability?    Progress:     I got the (a), $$\binom{10}{2}\binom{k-10}{18}\bigg/ \binom{k}{20}$$ But how do I get part (b) where $k$ is to maximize the probability? How to show that all points are inside of unit circle? There are $n$ points on the plane. Any $3$ of them are inside of a unit circle. How to show that all points are inside of unit circle?  It is needed to prove that if there is a unit circle for each $3$  points which contains them, there is also a unit circle which contains all $n$ points. Why are there two sets of the Ctrl, Alt, and Shift modifier keys when only one of each is necessary? If $\mathfrak p \subset R$ is a prime ideal, prove that for every nilpotent $r \in R$ it follows that $r \in \mathfrak p$.   The only hint that my tutor gave me was to use induction. Can someone explain what he means by this?  Thanks for the help! Stack Overflow technology makes me write bad answers Today I had some time and felt like writing a relatively good answer on Stack Overflow; explaining both the underlying mechanisms and good practices, unlike usual declarative answers in a "do that" style.  It took me like an hour of time, $50 if I were free lance. It'll bring me nothing but 3-5 occasional views, and - if I get lucky - some ignorant comments.  You know, it's quite discouraging.  Instead of pride for the job that was done, I feel frustrated. I know, this answer may offer help to the OP, if he ever notices it (being already satisfied with other answers).  So the only fate the answer will meet is to sink forever, below thousands other questions, falling like snow.  So, being a programmer, I am thinking of efficiency. It's a waste of time to spend so much effort to answer one question when there is no way to [actually] reuse it. So, I wouldn't do it again but just turn back into short answers mode without explanations.       Seeing other answers, I don't think I am only one with such feeling.  The current policy is driving knowledgeable and educational users away, yet it attracts inexperienced ones in numbers. Ones who will tell you to use [some technology] which they never have laid their hands upon. Ones who write answers just because they have learned some "good practice" from other questions, and this "knowledge" becomes an endless source of rep points.  The idea of Stack Overflow is rotten. It was excellent when trees were high and traffic was low.  It turned bad now; it has become a honeypot for all the "enthusiast programmers" of the world, eager to share their 2 cents faster than you can say the word "close".  You're killing a great resource. Despite all the nice words and proper declarations, it discourages the reuse of the knowledge. And encourages fast on-site answers.  Of course, the rules will tell you contrary. It's all nice and proper (if you don't mind it's strict mutual exclusivity). But mechanically, technologically it works in the way I described.  I tried to write a tag wiki. You know, it was biggest waste of time in my life. As a matter of fact, it is not a wiki at all; you can't even link to a certain section. Not to mention that nobody ever has the idea to read tag wikis.  Reference questions? Don't make me laugh. There is no good mechanism to store and categorize links. Favorites, although intended for the different purpose, are a chunk of crap when you want to use it as a reference. So, you can't compete with 30-seconds answers: a question will get 5 answers before you can even find an appropriate link.  Okay, I can organize links myself but, there are some problems:   I am just a human. I cannot remember everything I am just a human and I cannot answer questions at rate of 1 qpm. One person cannot fight the Tide. It's helpless. When technology makes people writing fast [incomplete] answers -  no good will of proper declarations can do a thing.  Even if a question gets finally closed, it won't hurt anyone - the hydra grew two more already.   You'll call me a brute for insulting honest users and innocent volunteers, but that's fact: There are much more inexperienced users than experienced ones. And inexperienced users have much more spare time to hang over than experts who have their job to do. So, from that fact we can conclude that most of the answers on Stack Overflow have a low quality. Nobody cares. But I do.   There should be a technical way to limit the activity of not-so-knowledgeable-yet-eager-to-answer users. There should be a technical preference for the closing a question over answering it (have a silly answer for the silly question? welcome to comments). There should be a technical solution to accumulate and structure knowledge, a system that lets you choose a good answer instead of writing it by hand.   That's the only way. Otherwise Stack Overflow will remain an automated dispenser of bad practices.  Well, I just felt like letting it out again. Thank you for reading. To reopen a closed question,  must agree that the question is suitable for the site and cast votes to reopen the question. But:  How does one actually vote to reopen? Is there a reputation level that you must have before you can see this function? Or do I just leave a comment along the lines of, &quot;I vote to reopen&quot;? What happens if someone with less than 3000 reputation leaves a comment that they wish to vote to reopen? How can one draw attention to their closed questions? Is it done via a posting new question? Or do you edit the closed question?   Related:  For more information, see &quot;&quot; in the . Suppose $X$ is a finite set and $f : X \to X$ is a function. Then $f$ is injective if and only if $f$ is surjective. Add a UIButton as a subview to a UITabBar Non constant analytic function from $\{z\in\mathbb{C}:z\neq 0\}$ to $\{z\in\mathbb{C}:|z|>1\}.$ How do I give text or an image a transparent background using CSS? Can't understand how to draw it. How can I copy/transfer games via external hard drive? I have successfully transferred "Killing Floor" from my brother's laptop to my own via external hard drive. The problem, now that I have all the files, is that I don't know how to launch the game through Steam. All I did was copy files from his Laptop to the hard drive, then from the hard drive to my laptop, then I put the files in the "Steamapps" folder under "Steam" in my laptops hard drive. So the question is, how do I start up the game through Steam? What is the difference between ethics and morals? I am currently writing an essay on artificial moral agents, and I need to explain the difference between ethics and morals. However, I am finding it really hard to find a good book or research paper which contains a citable definition.   Could someone point me in the right direction? Hibernate is disabled, hiberfil.sys gets recreated at each boot I have Windows 7 running on a small (40GB) partition, with 4GB ram. This means that the hiberfil.sys file created by Hibernate takes up a significant portion of the available diskspace. I would like to remove it.  I am aware that I can disable Hibernate and remove hiberfil.sys by entering powercfg -h off in an elevated command prompt. This works -- the file is immediately removed, and after doing so, the HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Power\HibernateEnabled key is (correctly) set to 0.  However, the next time I reboot the PC, hiberfil.sys returns from the dead, Hibernate is reenabled, and that registry key has returned to 1.  I'm pretty much at my wits' end with this. Almost everything I can find online related to removing the hiberfil.sys file simply suggests using powercfg to turn off hibernation, and that appears to work for just about everyone. But it just keeps coming back for me! (Like a vampire, sucking up my disk space.) I did find  from someone who seems to have had the same issue, but none of the suggestions there worked for the original poster (or for me). Still, I have tried everything listed there, including:   Disabling hybrid sleep Disabling Hibernate through the command prompt, through the Power Options GUI, and through both (in both orders) Manually changing the HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Power\HibernateEnabled key Pretty much everything else I can think of!   I do want to reiterate that I have no problem removing the file -- that works great. It just comes back after every reboot. I'm about ready to throw in the towel and just run a script on login to disable Hibernate each time, even though that seems like a crazily hacky "solution" . . . but I was hoping someone here could suggest something else, first. Irreducible cyclotomic polynomial Series as an integral (sophomore's dream) Can helium disappear from Earth? Helium is lighter than air, so it should fly off from Earth. Is it possible that in the future we will run out helium? $\mathcal N (A):=\mathcal P(A)\setminus\{\varnothing\}$ notation I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out? book recommendation on functional analysis