Why are object references different after assignment in a static method?
Is Java "pass-by-reference" or "pass-by-value"?
How to evaluate  $$\det\begin{bmatrix}1+x_1y_1&amp;\cdots &amp; 1+x_1y_n\\ \vdots &amp; \ddots &amp; \vdots \\ 1+x_ny_1 &amp; \cdots &amp; 1+x_ny_n\end{bmatrix}$$?  I tried factorisation but I have no idea. I could not factor anything out... I need a hint to kick off.   Edit: A conjecture due to multilinearity: if we let $v_j=(x_1y_j,\cdots,x_ny_j)^T$, then my guess would be $$\det\begin{bmatrix}1+x_1y_1&amp;\cdots &amp; 1+x_1y_n\\ \vdots &amp; \ddots &amp; \vdots \\ 1+x_ny_1 &amp; \cdots &amp; 1+x_ny_n\end{bmatrix}=\det(1,v_2,\cdots,v_n)+\det(v_1,1,\cdots,v_n)+\cdots+\det(v_1,v_2,\cdots,1)=\color{red}{0}$$ where $1$ denote $(1,\cdots,1)^T\in \Bbb K^n$,$\Bbb K$ the underlying number field. There have been several discussions regarding code-only answers (answers that contain only code blocks with no textual explanation whatsoever):         Personally, I can't see why the quality filter should let such answers through at all. The main problem I have with code-only answers, especially once they're flagged as not an answer or very low quality, is that we can't determine at a glance whether these answers are:   Genuinely attempting to answer the question  answers Trying to correct an error in the question without actually answering it Random code dumps that may or may not relate to the question even by programming language or keyword(s) in the question   In particular, what exactly is an "informative code-only answer"? Does it mean the code is self-documenting? Does it mean the code substitutes code comments for a proper write-up? This is all very fuzzy. From  to the last question above:     I have never seen a code-only answer that couldn't be made better with the addition of appropriate text. They are of lower-quality than the same answer with some text.   This text makes all the difference, IMO, between an answer and a non-answer. Without it, it's often needlessly difficult to tell.  Existing code-only answers that are good-faith attempts to answer the question should be edited or downvoted, yes. But if the quality filter already tries to block code-only questions, why not block code-only answers too? These answers are often low quality, and (almost) always have ample room for improvement, just like questions. list files and store it in variables I'm new with shell programming. My goal is to give the user a selection which file should be run. I catch all available scripts in one var with:  var=$(find script*)   so far so good, this is the output:      echo $var     script1 script2 script3 scr...   now I want to store each file in a singel variable to run it in later selection  select SEL in script1 script2 script3 .......... case $SEL in         $Script1) echo ($Script1 will start) &amp;&amp; ./$script1 ;;         $Script2) echo ($Script2 will start) &amp;&amp; ./$script2 ;;         $Script3) echo ($Script3 will start) &amp;&amp; ./$script3 ;;         $Sc..) echo ($Scr.... will start) &amp;&amp; ./$scrip.... ;;         $Sc...) echo ($Sc...... will start) &amp;&amp; ./$scrip..... ;;         *) echo "choose on of the availabel files";;     esac done   I don't have a clue how should I should separate all files if I don't know how many and the exactly length of each file.  I tried to split with echo ${var[1]} and echo $var[1] but this dosn't work. I recive either a empty output or the whole string. Why is AES considered to be secure? The security of RSA is based on the integer factorization problem, which is a very well defined and understood mathematical problem. This problem must be solved in order to fundamentally break RSA.   What about AES (and others based on the same idea)? Why is it difficult to break? Is there any mathematical principle that ensures its security? How would I write the equivalent of C#'s  in JavaScript?  var haystack = 'hello world'; var needle = 'he';  haystack.startsWith(needle) == true   Note: This is an old question, and as pointed out in the comments ECMAScript 2015 (ES6) introduced the  method. However, at the time of writing this update (2015) . What is the relationship between lands and mana in Magic and what do each of them do?  A good answer should especially include how a new player should think about them.    Note:  This is an attempt to create a canonical question about the relationship between lands and mana in Magic.  Beginners are often confused about this given the same symbols are used to mean different things across basic lands, non-basic lands, and mana costs.  This can lead to confusion about , about , or even about . What is the difference between "retired out" and "retired not out" in cricket? How to escape a single quote? This works fine:  sed -i 's#    @driver.find_element(:xpath, "//a\[contains(@href,##' temp_spec.rb   against a source of  @driver.find_element(:xpath, "//a[contains(@href,'change_district')]").click   I am just left with:  'change_district')]").click`   but when I try to add a single quote at the end it fails:  sed -i 's#    @driver.find_element(:xpath, "//a\[contains(@href,\'##' temp_spec.rb  syntax error near unexpected token `('   I am using \' to escape the single quote.  Note that I am using a # as a delimiter instead of the normal / delimiter as there are /'s in the text. Motor to spin slowly, low torque Let $f: \Bbb C \to \Bbb C$ be an entire (analytic on the whole plane) function such that exists $\omega_1,\omega_2 \in \mathbb{S}^1$, linearly independent over $\Bbb R$ such that: $$f(z+\omega_1)=f(z)=f(z+\omega_2), \quad \forall\,z\in \Bbb C.$$Prove that $f$ is constant.   The intuition seems clear to me, we have the three vertices of a triangle given by $0$, $\omega_1$ and $\omega_2$. All points in the plane are one of the vertices of that triangle under a suitable parallel translation. The constant value will be $f(0)$, fine. Throwing values for $z$ there, I have found that $$f(n\omega_1) = f(\omega_1) = f(0)=f(\omega_2) = f(n\omega_2), \quad \forall\, n \in \Bbb Z.$$  I don't know how to improve the above for, say, rationals (at least). Some another ideas would be:   Checking that $f' \equiv 0$. I don't have a clue of how to do that. Write $w = a\omega_1+b\omega_2$, with $a,b \in \Bbb R$, do stuff and conclude that $f(w) = f(0)$. This approach doesn't seem good, because I only have a weak result with integers above. Finding that $f$ coincides with $f(0)$ on a set with an accumulation point. This seems also bad: the set on with $f$ coincides with $f(0)$ by which I found above is discrete.    Nothing works and this is getting annoying... And I don't see how analyticity comes in there. I'll be very thankful if someone can give me an idea.  (On a side note.. I know that this title is not informative at all. Feel free to edit if you come up with something better.) Yes, I'm a moron, and I tried to manually install a higher point release of python 2.7.16 to /usr/bin/  (i did ./configure --prefix=/usr) on my Ubuntu 16.04 machine. It seems to work fine EXCEPT for packages that depended on python, like apt-listchanges, which fails with messages like ImportError: No module named apt_pkg  there's no make uninstall available, I've tried manually removing files, and still when I try apt --reinstall install python, Nothing gets overwritten and the python executable still gives the new 2.7.16 version...   Any idea how to get the official repository version back?? I develop a windows application and am curious whether it works via Wine. The application runs fine with Wine but I get no sound. In fact, I'm not sure whether my ubuntu installation has MIDI capabilities. The sound output settings shows "LFE on Separate Mono Output" one with "no amplifier" and another with "amplifier". They both function. I am using Ubuntu 12.04 as a client on virtualbox that runs on windows 7.  Thanks for any suggestion!  EDIT: virtual box hosted by windows 7, ubuntu running as a client in virtualbox. What is the meaning of this senctence:Excellent answer. Delusions of grandeur. Folks have been institutionalised for less Can an atheist at least agree that existence is a mystery that is bigger than all of us?                                                       You’ve got it backwards. It’s religious people who try to fill the mysteries of the universe with beliefs based on nothing emprical. Where atheists say “I don’t know” religious people say “It’s God.” Atheists are comfortable with not knowing everything. They know humans are infinitesimal specks in the universe. Religious people think the entire universe was created for and about them. Talk about grandiosity. Comment:Delusions of grandeur. Folks have been institutionalised for less lol Command line option to check which filesystem I am using? Is there a command that will show which file system (ext3, ext4, FAT32, ...) the various partitions and disks are using?   Similar to how sudo fdisk -l lists information about disks and partitions? Proving that $\lim_{n \rightarrow\infty} \int_{0}^{\frac{\pi}{2}} \sin(t^n) dt =0$ It is clear that $\lim_{n \rightarrow\infty} \int_{0}^{1} \sin(t^n) dt =0$. (which is not what is to be proved here)  I don't know how to proceed with the remaining part of the integral ie $\lim_{n \rightarrow\infty} \int_{1}^{\frac{\pi}{2}} \sin(t^n) dt$ (I tried substitution and partial integration).  Can anybody give me a hint ? How does a calculator calculate the sine, cosine, tangent using just a number? Sine $\theta$ = opposite/hypotenuse   Cosine $\theta$  = adjacent/hypotenuse   Tangent $\theta$  = opposite/adjacent      In order to calculate the sine or the cosine or the tangent I need to know $3$ sides of a right triangle. $2$ for each corresponding trigonometric function. How does a calculator calculate the sine, cosine, tangent of a number (that is actually an angle ?) without knowing any sides? Prove $e^{x+y}=e^{x}e^{y}$ by using Exponential Series In order to show $e^{x+y}=e^{x}e^{y}$ by using Exponential Series, I got the following:   $$e^{x}e^{y}=\Big(\sum_{n=0}^{\infty}{x^n \over n!}\Big)\cdot \Big(\sum_{n=0}^{\infty}{y^n \over n!}\Big)=\sum_{n=0}^{\infty}\sum_{k=0}^n{x^ky^n \over {k!n!}}$$  But, where should I go next to get $e^{x+y}=\sum_{n=0}^{\infty}{(x+y)^n \over n!}$.  Thanks in advance. I have been denied a visa several times in a row. How does one deal with such serial refusals? Remove space around tikz Let $p$ be a prime number and $G$ a non abelian group or order $p^3$. Prove that $Z(G) = [G,G]$.   I have already figured out that $|Z(G)| = p$, and that $G'=[G,G] \lhd G$.  Also, $|G'| = p$ or $p²$.  I suppose I'd have to prove that $G' \subset Z(G)$, but I've been trying and I have no idea how. Any hints? Thanks!