How to find name of the command locally
How do I find a command if I don't know its name?
How do I get a platform-dependent new line character? How do I get a platform-dependent newline in Java? I can’t use "\n" everywhere. Can we have a moderator only "flag for community team/developer attention" link on posts? How to pick a specific symbol from a specific font? Construct a network of citations Splitting string into pair of characters in Ruby How to install the Pantheon desktop environment? Unbounded continuous function on non-compact metric space Suppose $(S,d)$ is a non-compact metric space. Is it possible to construct an unbounded continuous function from $S$ to $\mathbb{R}$? If it is possible, please show the construction method :)  Here's my attempt to solve this problem: Because $S$ is not compact, we can find a neighborhood assignment function $N(x)$ so that a finite cover is not possible. Then each time we can find an uncovered point from the union of neighborhoods before, and change the function by $f(x):=max\{f(x),\text{a function which equals to the indice of this point at that point and gradually vanishes at further points from the selected point}\}$. However I'm concerned that while this function is unbounded, there may be some invalid points for this function (goes to infinity)...  EDIT: As I found out there is a duplicate question, however the elementary solution is not presented in that question, so I still wish to know about this problem. :) jQuery call function from a string Open CSV File with Different Delimiter Need of the cold body in heat engine What new capabilities do user-defined literals add to C++? I want to keep Ubuntu but remove Windows. I have Ubuntu 13.1 installed with the default window manager and DE.   I am trying to enable single click so I can open files and folders with only one click. I tried googling and all results said to open files, then go to preferences from top bar but my top bar has no options.  picture of desktop: How do I efficiently iterate over each entry in a Java Map? If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it,  what is the most efficient way of going through the map?  Will the ordering of elements depend on the specific map implementation that I have for the interface? Is there a way of maintaining malleability in a homomorphic encryption system while making it infeasible to perform chosen ciphertext attacks?   I have been reading about homomorphic encryption and malleable cryptosystems lately and have found it fascinating. I still have a lot of reading to do, however, I came across a statement in my reading that suggested malleability is inherently counter to security against chosen ciphertext attacks.  While I read up more about this relationship, I am curious to learn if there a way to maintain malleability while making a chosen ciphertext attack computationally infeasible? Why or why not? Testing for linear dependence among the columns of a matrix I have a correlation matrix of security returns whose determinant is zero. (This is a bit surprising since the sample correlation matrix and the corresponding covariance matrix should theoretically be positive definite.)  My hypothesis is that at least one security is linearly dependent on other securities. Is there a function in R that sequentially tests each column a matrix for linear dependence?  For example, one approach would be to build up a correlation matrix one security at a time and calculate the determinant at each step. When the determinant = 0 then stop as you have identified the security who is a linear combination of other securities.  Any other techniques to identify linear dependence in such a matrix are appreciated. Change the URL in the browser without loading the new page using JavaScript How would I have a  action that may have some effects on the current page but would also change the URL in the browser so if the user hits reload or bookmark, then the new URL is used?    It would also be nice if the back button would reload the original URL.  I am trying to record JavaScript state in the URL. Add a downvote option in the VLQ review There are many answers that are well-formed and well-formatted but are simply plain wrong or misleading. When reviewing, I often have a hard time deciding which action to take, as:   Looks Good: is OK per se but I would never say "good" (would work if the wording was changed slightly), Edit: The question is formatted well and editing it to be right would go against the intent of the author, Recommend deletion: this looks like the most reasonable choice, but I wouldn't flag it if I were browsing the site in normal mode, Not sure: I am quite sure what is wrong but I end up clicking this because the other three options do not seem fitting.   My proposal is to add a fifth option - Downvote that would make it easier to choose in case of such answers. Is it possible to flash a custom ROM without a custom recovery image For an un-rooted device, almost all articles/forum posts I've read say that in order to flash a custom ROM you first need to flash (or boot) a custom recovery image like TWRP.   I'm not sure I understand why. If the bootloader is unlocked shouldn't it be possible to manually flash images that make up the custom ROM to the required partitions with fastboot flash &lt;partition&gt; [ &lt;xxxx.img&gt; ], and leave the stock recovery untouched.  I realize that this may be difficult and that there is no benefit in doing it this way, but I'm curious to know whether or not it is possible, and if not, why? For the Quadratic Form $X^TAX; X\in\mathbb{R}^n, A\in\mathbb{R}^{n \times n}$ (which simplifies to $\Sigma_{i=0}^n\Sigma_{j=0}^nA_{ij}x_ix_j$), I tried to take the derivative wrt. X ($\Delta_X X^TAX$) and ended up with the following:  The $k^{th}$ element of the derivative represented as  $\Delta_{X_k}X^TAX=[\Sigma_{i=1}^n(A_{ik}x_k+A_{ki})x_i] + A_{kk}x_k(1-x_k)$  Does this result look right? Is there an alternative form?  I'm trying to get to the $\mu_0$ of Gaussian Discriminant Analysis by maximizing the log likelihood and I need to take the derivative of a Quadratic form. Either the result I mentioned above is wrong (shouldn't be because I went over my arithmetic several times) or the form I arrived at above is not the terribly useful to my problem (because I'm unable to proceed).  I can give more details about the problem or the steps I put down to arrive at the above result, but I didn't want to clutter to start off. Please let me know if more details are necessary.  Any link to related material is also much appreciated.