How to get datatype of an Object in Javascript?
(Built-in) way in JavaScript to check if a string is a valid number
Functional Equation (no. of solutions): $f(x+y) + f(x-y) = 2f(x) + 2f(y)$ Find all the functions $f\colon\mathbb{Q} \to \mathbb{Q}$ such that $f(x+y) + f(x-y) = 2f(x) + 2f(y)$, for all rationals $x,y$. Changing console font on Ubuntu 10.04 Server How can I change local console font on Ubuntu 10.04 Server to Inconsolata? How exactly do automatic updates work? I received an email this morning stating that my Wordpress site had been automatically updated to the latest version. I knew about the feature but I've always wondered exactly how it works.  PHP isn't a permanently-running process: it only runs when requested. So as far as I can tell, Wordpress can only update itself when someone loads a web page. But the update process is not instantaneous, so surely a user visiting the site would have a really slow page load.  Is there a different trick they use for automatic updates? I've searched all over the place but haven't found any explanation. We're injecting records into a journey using a Salesforce data event.  I also want to advance the people in the journey based on updates that happen in Salesforce (e.g., as an Opportunity record advances through the sales process), but I can't figure out how to do that.  I've read all the documentation I can find, but there doesn't seem to be a Journey Builder widget that will wait to be prompted by an event in Salesforce before continuing someone on a journey.  At the moment, I'm completely stuck.    I'd greatly appreciate any advice or information on how I can make journeys event-driven in this way.  Thanks very much! Does Blender support dual-GPU rendering if the two GPUs aren't the same? I have a GTX 1060 6GB in my current build, and I also have a GTX 960 2GB in storage. I was wondering if I got , and got both of my GPUs in one build (not SLI or CrossFire, just in the same system) would I be able to use both GPUs for rendering simultaneously? I don't care if this means having them both render separate tiles in one instance of Blender, or rendering separate frames in two instances. I'm using Cycles for everything I do. Do I have 32-bit or 64-bit? Prove that if $k\mid m,$ then $Z_m$ has a subgroup of order $k.$ Prove that if $k\mid m$, then $Z_m$ has a subgroup of order $k.$  Ok, so this doesn't look like too hard of a problem. So do I just show that it is closed under multiplication and inverse? I just don't know how I would do that with a problem like this. Can anyone help me get started please? How to get vertex normals from a shape-key in Python? I'm trying to create an exporter for a format, which includes shape key support. This format requires both vertex coordinates and normals to be specified. This should be logical, because the vertex selected on the image below won't have the same normals:     Comparing it to this one:    But I actually haven't found any way to export shape key normals. Both Bmesh Vertex and ShapeKey Vertex only store the coordinates.  Is there any way to get them? "Results found containing ___" too close to header The sign in the formula for the voltage across the inductor This question is about voltage induced in a inductance.  I know the rate of change of current induces EMF in the inductor. The direction of the induced EMF will be opposite to the change that is causing it. The EMF induced is given by the following formula.  $$V_l = -L \frac{dI}{dt}$$  The negative sign indicates direction of induced emf across the coil is opposite the current change.     In the picture I have drawn current direction and \$V_l\$ direction.  If \$\dfrac{dI}{dt}\$ is postive, \$V_l\$ will be negative according to formula right? Or does the direction of \$V_l\$ has to be reversed?  In many Internet references I found \$V_l = L \dfrac{dI}{dt}\$. Which one is correct?  I hope they reversed \$V_l\$ reference points and removed the negative sign in the formula. Please clarify. How to prepare files for rsync on a case insensitive filesystem? I am transferring a large number of files on a HFS+ filesystem.  The files are currently on ext2 partitions.  I have conflicts due to case insensitivity of the target partition (HFS+).  I want to identify the files that have duplicates filenames once they are in lower case, and delete them if they are actually duplicates.  I also found that I will have duplicate folder names if I convert everyhing to lower case. Basically these hard drives contain years of unsorted data, and I happen to have this problem with folder names too.   Does this seem reasonable:  find . -type f | while read f; do echo $f:l; done | sort | uniq -d    $f:l is ZSH for convert to lower case.  Now I want to keep only one instance of each file that have duplicates. How to do this efficiently ?  I do not want to find files with duplicate content, unless they have the same lower case filename. I will deal with duplicates later. Finding critical points (extrema) directly without using eigenvalues If we have a function $f: \mathbb R^3\rightarrow \mathbb R$ of the form:  $$f(x)=(a_1x_1^2+a_2x_2^2+a_3x_3^2)e^{-x_1^2-x_2^2-x_3^2}$$  where $a_1&gt;a_2&gt;a_3&gt;0$.   We can find the critical points by:  $$\frac{\partial f}{\partial x_1} =2x_1e^{-x_1^2-x_2^2-x_3^2}(a_1-a_1x_1^2-a_2x_2^2-a_3x_3^2)=0$$  And solving symmetrically for $x_2$ and $x_3$. We get critical points: $(0,0,0) , (\pm 1,0,0) , (0,\pm 1, 0) , (0,0,\pm 1)$   We could determine the nature of them by looking at the eigenvalues of the Hessian, but is there a way to just analyse it directly? Obviously $(0,0,0)$ is a strict global minimum, but I can't quite see that the other points are. Any pointers/hints would be appreciated. Using the definition of Riemann integrability, prove that $f $is Riemann integrable on $[0,1]$ The following problem came up on a test, and I didn't get it correctly. Please help me understand the problem.  Problem: Define $f:[0,1] \to \mathbb{R}$ by $$     f(x)=  \begin{cases}     1,&amp; \text{if } x=\frac{1}{n}\\     0              &amp; \text{otherwise} \end{cases} $$ for some integer n.  Using the definition of Riemann integrability, prove that f is Riemann integrable on $[0,1]$ and evaluate the Riemann integral $\int_{0}^{1} f(x)dx$.  My Solution:  Let $\epsilon&gt;0$ and $P$ be the partition of $[0,1]$ such that $P=\{0,\frac{1}{n}- \frac{\epsilon}{3},\frac{1}{n}+ \frac{\epsilon}{3},1\}$.Then note that   $U(f,P)=M_0\Delta x_0 +M_1\Delta x_1+M_2\Delta x_2=0+(\frac{1}{n}+ \frac{\epsilon}{3})-(\frac{1}{n}+ \frac{\epsilon}{3})+0=\frac{2\epsilon}{3}$ and   $L(f,P)=0$.   Thus, for every $\epsilon&gt;0$ $$U(f,P)-L(f,P)=\frac{2\epsilon}{3}&lt;\epsilon$$.  This is the prove that I gave and the mistake that I made was that I fixed n. Some important things that I noticed about this problem were that if you graph the function $f(x)$ most of the points fall to the left or close to zero and a fewer fall to the right. Hence, this makes me believe that I need a partition such that I capture most of the points near zero so that I am only left with a finite number of points close to 1. However, I can't seem to find this partition.Any help would be appreciated. In particular, I would like to know how you come up with the partition since I always struggle to come up with one. Thank you! reCaptcha v1 is shutting down on March 31, but SEDE still uses it According to this , I thought the new recaptcha API was used network-wide. Though today, when going to  (which for whatever reasons never recognized me automatically), I got this message instead of a usable captcha image.   V1 Unsupported Please direct siteowner to   (Doing a second try doesn't show this message anymore, and the recaptcha v1 works as intended.)  According to , the reCAPTCHA v1 API will stop working on March 31, 2018:  What happens to reCAPTCHA v1? Any calls to the v1 API will not work after March 31, 2018. Starting in November 2017, a percentage of reCAPTCHA v1 traffic will begin to show a notice informing users that the old API will soon be retired. Most websites around the world have already switched to reCAPTCHA v2, where humans pass effortlessly. With our advanced risk analysis engine, reCAPTCHA v2 can effectively separate humans from bots and always stay ahead of the attackers. If your site still uses reCAPTCHA v1, please upgrade to reCAPTCHA v2 immediately. We no longer support reCAPTCHA v1. Any calls to the v1 API will not work after March 31, 2018. Please register a new key and upgrade to v2.  I'm really hoping this will not take  to fix, because we've only got three and a half weeks left! Dual boot windows 8 and Ubuntu with Windows 8 Boot manager How can we get rid of misspelled and unused (or "zombie") tags? During the re-tagging of questions, tags sometimes become orphaned from existing questions.  Are these zombie tags ever removed from the ?  What if a tag is misspelled and needs to be removed? How do we get rid of it? Is 'hair' singular or plural? When one says I was washing my hair, is it singular or plural? What is the singular for hair? SQL Server - Best way to get identity of inserted row? What is the difference between:   The company would rather each employee be provided with ID card.  The company would rather each employee were provided with ID card. In Inno Setup is it possible to add conditional statements to what in the [Run] section gets executed? Alternatively is it possible to manually update the built in progress bar? Basically I have 2 MSIs included and using Inno Setup as a bootstrapper, and depending on user input one or both of the MSIs are to be installed.  I have something working using Exec statements in CurStepChanged but it doesn't update the progress bar as the files are extracted and it looks like the installer is stalled.  I guess the end result is I want some progress bar updates while the files are extracted to the temp folder.  The following is my current code:  procedure CurStepChanged(CurStep: TSetupStep); var     ResultCode: Integer; begin     if(CurStep = ssInstall) then begin         if(InstallServer) then begin             ExtractTemporaryFile('ServerSetup.msi');             Exec('msiexec',ExpandConstant('/i "{tmp}\ServerSetup.msi" /qb INSTALLDIR="{code:GetInstallPath}\Server\" ALLUSERS=2'),'', SW_SHOW, ewWaitUntilTerminated, ResultCode);         end;         if(InstallClient) then begin             ExtractTemporaryFile('ClientSetup.msi');             Exec('msiexec',ExpandConstant('/i "{tmp}\ClientSetup.msi" /qb INSTALLDIR="{code:GetInstallPath}\Client\" ALLUSERS=2'),'', SW_SHOW, ewWaitUntilTerminated, ResultCode);         end;     end; end;