I downloaded NodeJS from the official website as a tarball and extracted it but I can't install it. The BULDING.md file says I should  ./configure   then  make -j4   However, trying ./configure inside the directory returns this error:  bash: ./configure: No such file or directory   I solved this error (see the comments), but now after running make -j4 I get this error:  node bin/npm-cli.js install marked --no-global --no-timing --no-save node bin/npm-cli.js install marked-man --no-global --no-timing --no-save bash: node: command not found bash: node: command not found Makefile:154: recipe for target 'node_modules/.bin/marked' failed make: *** [node_modules/.bin/marked] Error 127 make: *** Waiting for unfinished jobs.... Makefile:159: recipe for target 'node_modules/.bin/marked-man' failed make: *** [node_modules/.bin/marked-man] Error 127   yet I have all dependencies (git, python, g++ and make). What am I missing here? Note: I know I could install it using apt but I want to use this as part of learning.
How do I install the latest  on Ubuntu? I've been looking around, and I can't find anything. Is there a Ubuntu package for node.js, or do I have to compile it myself?
Let ($x_s$) be a convergent sequence, where $x_s&gt;0$ for all s, and $y_s$ be a sequence such that   $$\displaystyle \Large y_s=\frac{s}{\frac{1}{x_1}+...+\frac{1}{x_s}}$$  Prove $\displaystyle \lim x_s$=$\lim y_s$  So I know things like $x_s$ is bounded, and that it's Cauchy, but I can't think of anything to solve it.  Any help is appreciated. Do mankind and manmade activities/constructions have any effect on the rotation of the Earth? Trigonometry and algebra question Given:   The total length of ad + dc The lengths of each ab, bc and ca That angle adb = angle cdb   How can I work out lengths ad and cd Differentiation - simple case Backup of clients' directory to Windows Server 2008 We have a machine running Windows Server 2008, and we need to take backup of folder from a desktop on LAN. This folder is not shared.   Is there any tool or software to do this, or can a scheduled task be made which should automatically take the backup of that folder date-wise &amp; make a copy on server? Ie can we do it through Schedule Tasks option ?  Desktop systems have Windows Vista/Windows 7. Version Control: Entire site or just pieces? I've been using git to track changes in the plugins and themes I've developed for different sites. Each plugin or theme has their own repository in whichever local install of WordPress I happen to be using for that project. This works fine when I'm just working on one solitary plugin or theme.  But when I have a local version of an entire site which is a collection of different plugins, themes, WordPress core, etc. Should I be keeping that entire directory under version control?  Is there a best practice to always have a collection of repositories for each theme/plugin, or for each client site to have one monolithic repository that includes all the code used in the project (including the latest copy of WordPress via svn.) Find the maximum likelihood estimator for $\theta$ when $f(x)=2\theta^{-2}x, 0\leq x \leq \theta$ Find the maximum likelihood estimator for $\theta$ when $f(x)=\frac{2x}{\theta^2}, 0\leq x \leq \theta$.  This should be a really easy question but I somehow cannot seem to get the right answer. My likelihood function is $\prod\limits_{i=1}^n \frac{2x_i}{\theta^2}$ which gives me after some simplification $n\ln(2\theta^{-2}) + \sum\limits_{i=1}^n ln(x_i)$ as my log-likelihood function. Then the derivative becomes $\frac{-2n}{\theta}$. If I equate this to $0$ to obtain the maximum I obtain $\hat{\theta}\rightarrow\infty$. However, this answer does not seem plausible. What did I do wrong? Slower download speed compared to Windows on Ubuntu 20.04 How do you get the footer to stay at the bottom of a Web page? I have a simple 2-column layout with a footer that clears both the right and left div in my markup.  My problem is that I can't get the footer to stay at the bottom of the page in all browsers.  It works if the content pushes the footer down, but that's not always the case. What is the evidence that dark energy exists? (as of 2020) Astrophysicists believe that dark energy exists and makes up ~70% of the universe's energy content. What is the evidence that dark energy exists? Wikipedia gives :   Supernovae. A specific type of supernovae (type 1A) are supposed to be standard candles - that is, their luminosity is known. In turn this lets us measure distance to faraway galaxies, check how fast those galaxies are receding from us, and check if that recession speed is increasing over time. CMB. Data from the Cosmic Microwave Background indicates the universe is approximately flat. Visible matter + dark matter can account for ~30% of the energy content required to make the universe flat, leaving ~70% for something else - dark energy. BAO. Baryon acoustic oscillations act as a "standard ruler" that lets us measure how the Hubble constant varies with redshift (i.e. time), and see if the recession speed is increasing with time. Late-time ISW. ISW stands for integrated Sachs-Wolfe effect. The idea is that, usually, a photon that enters a potential well gains energy as it falls in and loses energy as it emerges, and gain/loss exactly cancel. If a universe is expanding in accelerated fashion, then this is untrue; the potential wells / hills are smoothed out and there is a permanent shift in the photon's energy and therefore temperature. If we see a correlation between hot and cold spots on the CMB and the locations of superclusters and voids, then it's a sign of accelerated expansion. Galaxy evolution. This uses (known) evolution of early-type galaxies as a standard clock. Once we know how long it takes for a galaxy to evolve from one state to another, as well as their redshifts, we can reconstruct how the Hubble constant varies over time, and see if the recession speed is increasing with time.   Two questions:   Did I understand any of these five methods wrong? Are there any other lines of evidence for the existence of dark energy? $e^{mx}$ in solving second order differential equations In a book I am reading on differential equations, the author writes about the solution to a homogenous, linear, second order differential equation with constant coefficients. The author says something like, "Let us suppose that the solution is of the form $y=e^{mx}$ " . After this the author introduces the characteristic equation of a differential equation of the form mentioned above, and proceeds to describe how to solve it w/ undetermined coefficients, variation of parameters, etc.   How did mathematicians first come up with this "assumption" that the solution was of the form $y=e^{mx}$? And, are there any other forms of solutions for these types of equations? Predicting the number of decimal digits needed to express a rational number The number $1/6$ can be expressed with only two digits (and a repeat sign denoted as $^\overline{}$), $$ \frac{1}{6} = \,.1\overline{6}$$  Meanwhile, it takes 49 digits to express the number $1/221$, since a string of 49 digits repeats: $$\frac{1}{221} = .\overline{004524886877828054298642533936651583710407239819}$$ Yet for $1/223$, 222 digits repeat, giving a total of 224 digits needed to express the number.  If $f:\mathbb{Q}\rightarrow\mathbb{N}$ is a function that gives the smallest number of digits needed to express a rational number in decimal notation, what can we say about $f$?  For example, if we do not consider the negative sign to be a digit, then $f$ is an odd function.  Other than that, is there any pattern to it at all? Which computer science / programming Stack Exchange sites do I post on? Unexpected Results From Clicking The Unanswered Button Purpose: Construct a 95% confidence interval for $\theta$.   A common strategy is to construct a confidence interval for $\log(\theta)$ and then exponentiate.  Why is it valid?   My concern is that $E(\log(\theta)) \neq \log(E(\theta))$ and $Var(\log(\theta)) \neq \log(Var(\theta))$...   Do people use this back transformation because it has proven to work fine? What about other transformations (e.g. logit)? Evaluating and proving $\lim\limits_{x\to\infty}\frac{\sin x}x$ I've just started learning about limits. Why can we say $$ \lim_{x\rightarrow \infty} \frac{\sin x}{x} = 0 $$ even though $\lim_{x\rightarrow \infty} \sin x$ does not exist?   It seems like the fact that sin is bounded could cause this, but I'd like to see it algebraically.   $$ \lim_{x\rightarrow \infty} \frac{\sin x}{x} =  \frac{\lim_{x\rightarrow \infty} \sin x} {\lim_{x\rightarrow \infty} x}   = ? $$  L'Hopital's rule gives a fraction whose numerator doesn't converge. What is a simple way to proceed here? What does "I have got some time on my hands" mean? My shift at work's kinda long, so I've got some time on my hands to, you know...whatever. Think, I guess.   What does "I have got some time on my hands" mean in the above quote? I think this is a duplicate of an old question without a good answer:  My child was doing schoolwork on her school-issued Macbook Air. Suddenly lighter greys are totally white. This generally gives the images on the screen a vague feeling of being &quot;off&quot;, and pixellates all curved edges. The biggest problem is that text on some of her sites is unreadable. I've checked the following:  Color profiles - it looked like it was using the default, but a cycled through a few built-ins. I could see noticeable changes to color balance, but the light greys remained the same as white. Also deleted contents of ~/Library/ColorSync/. Accessibility - my child has accidentally inverted colors before, this isn't that. No other accessibility settings seemed related to color. Display settings - Modifying brightness was also fruitless. The screen overall got brighter or darker, but still couldn't distinguish between light grey and white Rebooting - colors look fine until shortly after logging in - seems connected to user profile somehow.  Here are some images to demonstrate the issue. This is a generic color test image:  On the Mac, it looks like this (simulated with photoshop):  Any solution would be appreciated, but if there is a keyboard shortcut that can cause this, it would be the most likely explanation (8 year old says they &quot;might have rested their arms on the keyboard&quot; during a class meeting) Draw integers independently & uniformly at random from 1 to $N$ using fair d6? I wish to draw integers from 1 to some specific $N$ by rolling some number of fair six-sided dice (d6). A good answer will explain why its method produces uniform and independent integers.  As an illustrative example, it would be helpful to explain how a solution works for the case of $N=150$.  Furthermore, I wish for the procedure to be as efficient as possible: roll the least number of d6 on average for each number generated.  Conversions from  to decimal are permissible.    . Origins of the nose-bleed in anime/manga In a similar spirit to my , I wonder who was the first artist to feature a nose-bleed when thinking, shall we say, "provocative thoughts"?  Did it become popularized in anime/manga because of the popularity of the artist's work or because it is a common belief in japanese folklore?