Should a Java singleton use static variables?
Difference between static class and singleton pattern?
I want to create a function that performs a function passed by parameter on a set of data. How do you pass a function as a parameter in C? How can I change the umask for one command only? How can I interactively execute a command in Linux (zsh, if it matters) with a different umask from the default, for one command only? Perhaps a combination of commands combined in a single line? The new umask should apply only to that command and return to its default value for the next command entered.  Ideally the command would be agnostic to the default umask in force before its entered (in other words, the default umask doesn't have to specified). I want to have a script that takes the current working directory to a variable. The section that needs the directory is like this dir = pwd. It just prints pwd how do I get the current working directory into a variable? Child who entered under ESTA/VWP accompanying US citizen mother It started happening today... all of a sudden, no apparent reason!  Here's the output from df:   assp:~# df -k Filesystem           1K-blocks      Used Available Use% Mounted on /dev/simfs             6291456   1378384   4913072  22% / tmpfs                  8202680         0   8202680   0% /lib/init/rw tmpfs                  8202680         0   8202680   0% /dev/shm  assp:~# df -i Filesystem            Inodes   IUsed   IFree IUse% Mounted on /dev/simfs           55781934   83005 55698929    1% / tmpfs                2050670       2 2050668    1% /lib/init/rw tmpfs                2050670       1 2050669    1% /dev/shm  assp:~# df -h Filesystem            Size  Used Avail Use% Mounted on /dev/simfs            6.0G  1.4G  4.7G  22% / tmpfs                 7.9G     0  7.9G   0% /lib/init/rw tmpfs                 7.9G     0  7.9G   0% /dev/shm   Here's an actual entry from /var/log/mail.warn:   Dec 11 17:55:37 assp postfix/smtpd[30614]: warning: not enough free space in mail queue: 0 bytes &lt; 1.5*message size limit Dec 11 17:55:37 assp postfix/cleanup[30617]: warning: 4361D850D54: write queue file: No space left on device   . How to pass data from Javascript to PHP and vice versa? Can current be induced in a superconductor? I am not sure which conjunction to use in the following context:        I know about programming but I have a little bit of confusion in Java programming.   I know about programming although I have a little bit of confusion in programming.    I know about programming however I have a little bit of confusion in Java programming. Formal power series ring, norm. Let $k$ be a field. Let $R$ be the formal power series ring $k[[x]]$. Define $N$ on $R \setminus \{0\}$ as follows: $N(f)$ is the smallest $n$ of which the coefficient of $x^n$ in $f$ is nonzero.  (a) Prove that $R$ is a Euclidean domain with Euclidean norm $N$.  (b) For $a$, $b$, $a+b$ nonzero elements of $R$, prove that $N(a+b)$ cannot be bounded as a function of $N(a)$ and $N(b)$.  (c) Prove that if $a$ and $b$ are two power series such that $b$ does not divide $a$ (and $b \neq 0$), there are infinitely many pairs $(q, r)$ for which $a = bq + r$ and $N(r) &lt; N(b)$. On my y510p, I set Lenovos battery software to "Optimize battery health" while I was in Windows 8.1. I forgot to change it before overwriting that partition with Ubuntu, and now my battery in Ubuntu never charges past 59~60%. I think this is due to something in the BIOS because it persists despite my Windows partition being gone.   I've searched the BIOS but there's no mention of battery anywhere!  I'm using Ubuntu 14.04 LTS. My distribution is normal; Kolmogorov-Smirnov test doesn't agree I have a problem with the normality of some data I have:  I've done a Kolmogorov test which says it isn't normal with p=.0000,  I don't understand: the skewness of my distribution =-.497, and the kurtosis =-0,024  Here is the plot of my distribution which looks very much normal ...  (I have three scores, and each one of this scores isn't normal with a significant p-value for the Kolmogorov test ... I really don't understand ) I am from Europe, and I did an internship in the US (California) in 2015. When filing my 2015 taxes, I ended up having to pay some small difference for the federal taxes, but got a refund on my state taxes, of roughly $1.6k. That was all the income I had in the US in 2016.  I did not enter the US in 2016 at all.  I managed to figure out that I don't need to file any California tax forms for 2016 (source: ) but I am not sure about federal taxes.  I tried researching the problem, and got some information on it, but the situation is still a bit unclear. It seems that since I listed my state tax as an itemized deduction in my 2015 tax report, which I filed in 2016, the state refund I got in 2016 is, in fact, taxable.  In this situation, would I have to file my taxes (and possibly pay owed tax) for 2016, even though I never set foot in the US in that year, and my total income is just $1.6k? I have created two files:  sample.txt and sample.txt  (the second file contains some hidden characters, e.g. a space). How can I remove the latest modified file? I'm using Linux. What is the difference between user and service account? Can a regular salaried (w2) employee opt to pay quarterly taxes? As a consultant, I got used to paying quarterly taxes. Now that I'm a regular w2 salaried employee, I'm subject to normal withholding on each pay statement. I would like to keep making exact quarterly payments instead of having a (generally incorrect) amount held back each paycheck.   I haven't been able to find any information on the 1040-es that would make me think I'm ineligible to do so, but I suspect that it may be the case. I'd have to stop paycheck withholdings by updating my w4 to either have a high number of exemptions or mark myself as exempt from taxes, which I assume is where the rub lies.   So, as a regular salaryman, is it possible for me to pay taxes exclusively through quarterly payments in lieu of traditional withholdings? Viewshed analysis plugin on QGIS keeps resulting in errors I've been trying to test the Viewshed analysis plugin on QGIS 2.10, but it keeps giving back error messages. I've tried to reduce the radius area and have also reprojected both my DEM and my point shapefile to UTM, in order to avoid a possible memory error mentioned in another question regarding this plugin (that the using of geographic coordinates might cause a memory error).  Still, I keep getting Python error messages when I try to run it. Does anyone know whats going on? Is this plugin "broken"? What is the inverse function of $e^x +x$? Is the following proof correct, or are certain steps illegal?  Suppose $f:G_1\to G_2$ is a surjective group isomorphism, $N_1\lhd G_1, N_2\lhd G_2$ normal subgroups, with $N_1=f^{-1}(N_2)$. Prove that $(G_1/N_1)\cong (G_2/N_2)$.  Proof:  As $f$ is surjective, we an use the first isomorphism theorem to get $G_1/\ker(f)\cong G_2$, which implies that $$(G_1/\ker f)/(N_1/\ker f)\cong G_2/(N_1/\ker f)$$  Using the first isomorphism theorem we also know that $$N_1/\ker (f)\cong f(N_1)=f(f^{-1}(N_2))=N_2$$  Combining this we can see that $(G_1/\ker f)/(N_1/\ker f)\cong G_2/(N_1/\ker f)\cong G_2/N_2$.  Using the third isomorphism theorem we have that: $$ (G_1/\ker f)/(N_1/\ker f)\cong G_1/N_1$$  And from the last two lines we have $G_1/N_1\cong G_2/N_2$ $\tag*{$\Box$}$ Keep sharp edges when using subdivision surface How can I use the subdivision surface modifier to create more high poly meshes without ruining sharp edges? For example this mesh  The sphere should be subdivided but the rim of the cylinder should stay the same because it is a sharp edge. This is the result of the subdevision  How can I get sharp edges to not be affected by the sub surf mod? I have 2-3 different column names that I want to look up in the entire DB and list out all tables which have those columns. Any easy script?