Install Node.js in Ubuntu 14.04 I installed Node.js with:  sudo apt-get install nodejs   But when I type in a console node I get nothing, no command not found, no any error. But when I type nodejs I get the Node.js prompt &gt;.  Now, I can't install anything with npm, I tried to install yeoman with: sudo npm install -g yo but I got an error, something related to node. I tried to change the command with:  sudo ln -s /usr/bin/nodejs /usr/bin/node   But still nothing happens when I type node  What is the right way to install Node.js on Ubuntu? Or what am I doing wrong? Or what am I missing?
How to install the latest versions of NodeJS and NPM? I noticed over at the  website that node is currently at v 0.12.0.  Can someone let me know how to install the latest version of node together with npm (terminal commands please)?
Why does the base of this slinky not fall immediately to gravity? My guess is tension in the springs is a force > mass*gravity but even then it is dumbfounding. Show that no application $f: \mathbb{R}^2 \rightarrow \mathbb{R}$, of $C^k$ class, $k \geq 1$ can be injective How can I proof this:     Show that no application $f: \mathbb{R}^2 \rightarrow \mathbb{R}$, of $C^k$ class, $k \geq 1$ can be injective, i.e., there are $A,B \in \mathbb{R}^2$ such that $A \neq B$ and $f(A) = f(B)$ (Hint: show that given $(a,b) \in \mathbb{R}^2$ in every open neighbourhood of $(a,b)$ there are points $(c,d),(c_1,d_1)$ where ${\partial}_1f(c,d) \neq 0$ or ${\partial}_1f(c_1,d_1) \neq 0$).   The problem is that I have no idea how to use the hint.  Thanks for all your comments. Are users' reputation scores on the home page supposed to stand out that much now? It seems a couple minutes ago, a change was applied to the styling of the homepage, with users' rep scores now being much darker (and standing out more):        Compare with the former light grey colouring (image courtesy of ):        Is this intentional? If so, why? It highlights something that's not really relevant, in my opinion. Top-bar hat misplaced In my profile my hat is on the correct position, but not in the top-bar. This is new. It worked until now.    Works neither in Chrome nor in Firefox. I have a training set with about 3000 positive instances and 3000 negative instances. But my test data set is pretty much un-balanced. The positive set only has 50 instances and negative has 1500 instances.This causes the precision very low. Are there any approaches to solve this problem? I use SVM to build classifier. How can I add a "C" wire to my thermostat? escaping double quotes and percent signs (%) in cron The following command works from prompt but not from crontab.   grep abc  /var/log/messages | grep "`date '+%B %d'`" | mail -s"abc log of `hostname`" shantanu.oak+`hostname`@gmail.com   I need to add it to daily cron. I'm try to change to my Desktop directory from the terminal.  Running  cd /home/desktop   gives an error in the terminal saying no directory found.  What am I doing wrong? I have never found experimental evidence that measuring one entangled particle causes the state of the other entangled particle to change, rather than just being revealed.  Using the spin up spin down example we know that one of the particles will be spin up and the other spin down, so when we measure one and find it is spin up we know the other is spin down. Is there any situation after creation that the particle with spin up will change to spin down? Computation of likelihood when $n$ is very large, so likelihood gets very small? In the 1960s I read book--an older children's book, I think--which I loved, and still remember, roughly.  I have no idea what the title is or who the author is, and I'm wondering if anyone knows this one:  Scientists had invented a device which they didn't fully understand, and which had puzzling effects.  For example, when a pencil was put into the machine, it disappeared, and then reappeared inside out: The lead was on the outside.  When people went into the machine, they came back dead, having died from fright.  Finally they sent a very open-minded person into the machine.  She was an artist, I think.  She was able to return alive, and described an alternate universe in which geometry was very different.  I distinctly remember that there were supposedly square triangles or four-sided triangles--or was it three-sided squares?  (This is, of course, a literally contradictory claim, but I didn't see the matter as clearly then.)  Thanks! Image data URI and SEO Do you think the use of image data URI is SEO friendly?   On the one hand saves you a HTTP request. On the other hand it really messes up your code. Especially for image files larger than 20KB or moving GIF image files of up to 200KB, the quantity of code inserted is enormous. As Googlebot reads usually from top to bottom, all data after the image data URI encoding will be harder to rank well in Google.   Consider that image data URI is not in the CSS files as they should normally be and for the time being I can use only TinyMCE editor which provides me with just two options, either insert image with the image data URI method or the traditional image link.   I would like to know which is more search engine friendly. Holomorphic self map on the open unit disc I've noticed a MATCH SIMPLE and MATCH FULL, but I don't understand what they do. I see default is MATCH SIMPLE; but, how do the other MATCH clauses to the FOREIGN KEY constraint function? $(\Bbb Z\oplus \Bbb Z)[X] \not\cong \Bbb Z[X]\oplus \Bbb Z[X]\,$? Well i tried to prove it but failed. They are both commutative and have the same set of units. So i can't see a property of one ring which the other ring does not possess. Thank you for any help. Vector. Properties It is given in a question that $\vec x+\vec a=(\vec a\cdot \vec x)\vec b$ and it is stated that $\vec a$, $\vec b$ and $\vec x$ are vectors.  It is also stated that $\vec a\cdot \vec b\ne 1$.  The question asks to express $\vec x$ in term $\vec a$ and $\vec b$.  How do you this? How can I safely prototype a mains power circuit? I'm building a device that has a mains power component, which I need to prototype before building to make sure everything works. I know I need to make sure wiring—and insulation!—is thick enough to cope with the higher current, and that I need to make sure there's enough space between exposed components so there's no arcing. I'll also be stashing whatever I prototype in a nice, insulated box before applying power, and I'll be include a small-value (250mA) fuse just in case. I'll be considering everything double-insulated rather than earthed (plastic enclosure, and there's nothing I'll need to touch while it's operating).  My plan is to solder (through-hole) components directly to each other, then insulate everything (with heatshrink tubing or electrical tape) as much as possible, then use screw-type cable joiners to connect the power cable.  I know I can't use traditional prototyping tools such as breadboards and stripboard for mains voltages, but what can I use to make prototyping at mains voltages easier?  (To be clear, 'mains voltage' in my area means 230V AC +10/-6% at 50Hz; GPOs are generally rated at 10A.) How to load Windows 7 from GRUB rescue I have a dual boot setup with Ubuntu and Windows 7. I need to shrink my root Ubuntu volume in order to get some free space to create a new partition. Are there any Windows based tools that will do this for me? I tried booting up in gparted to do this but I cannot tell which partition is which since I cannot find the size (it displays everything in blocks). A physical explanation for negative kelvin temperatures