How to build a regular expression for a host name?
Regular expression to match DNS hostname or IP Address?
Matrix representation of linear transformation Is there a good resource or tool to help build a palette/color scheme around colors I select? No matter how nice the composition, flow, and lines of my design are, if I am not copying directly from nature, I have a very difficult time picking a decent color scheme.  It either looks too drab, or too garish.  Is there a good resource that will help me to choose a color scheme that has 2 or 3 colors, and the colors do not clash?  I'm not looking for specific colors or color schemes.  What I need is a resource that will help me choose a color (or colors) that go nicely with, or provide a good accent to, whatever main color I am working with on the design. I've seen sign in methods using  as an authentication provider, for example : (AWS Cloud9)        Is it possible to authenticate into Stack Exchange using this method? At the moment there's other methods such as OpenID, Google, Yahoo and Facebook, but it would be interesting to also have the GitHub authentication. Is there a significant difference between "rock" and "stone"? I found this pretty good small research, but I am still concerned about "regular usage" in life, say, when I am talking in the office, especially because of this comment:     To me: Stone is something you can pick up with one hand (for   throwing). A rock takes two hands. Torus and Elliptic curves In a conference on elliptic curves (an introduction to the subject), the speaker said that an elliptic curve (I.e. an equation of the form $y^2=x^3+ax+b $ where the RHS has distinct roots) is, in the complex space, a torus/Riemann surface of genus 1.  What is meant by that? Are we talking about a 2-dimensional manifold the 4D space? Completely synchronise multiple Macs How to set the same font size for all tables? Increasing sequence of step functions and diverging Lebesgue Integrals Let $\{s_n\}$ be an increasing sequence of step functions which converges pointwise on an interval $I$ to a limit function $f$.  If $I$ is unbounded and if $f(x) \geq 1$ everywhere on $I$ except on a set of measure zero, prove that the sequence $\{\int_I s_n\}$ diverges.  (Here $\int_I s_n$ refers to the Lebesgue Integral.)  Conceptually, this makes sense.  Clearly, if $f(x) \geq 1$ almost everywhere on an unbounded interval, then the sequence of Lebesgue integrals should diverge.  However, in proving this, I am running into issues with the convergence of $\{s_n\}$ being pointwise.  If it were uniform, I could easily show this.  How do I show that (even for pointwise convergence) I can choose $n$ large enough to make $\int_I s_n$ as big as I want? Newton's cradle How to get ObjectContext to compile? Why can't we initialize members inside a structure? Ubuntu 20.04 no sound out of Bluetooth headphones I have an ASUS E402S laptop with Ubuntu 64-bit 16.04 LTS installed. The main problem is that the OS does recognize the touchpad with basic functions, but additional options such as scrolling through pages or between open applications are non-existent.  This is what my xinput result is showing:  ⎡ Virtual core pointer                      id=2    [master pointer  (3)] ⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)] ⎜   ↳ Logitech USB Receiver                     id=9    [slave  pointer  (2)] ⎜   ↳ Logitech USB Receiver                     id=10   [slave  pointer  (2)] ⎜   ↳ FTE1000:00 0B05:0101                      id=12   [slave  pointer  (2)] ⎣ Virtual core keyboard                     id=3    [master keyboard (2)]     ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]     ↳ Power Button                              id=6    [slave  keyboard (3)]     ↳ Video Bus                                 id=7    [slave  keyboard (3)]     ↳ Sleep Button                              id=8    [slave  keyboard (3)]     ↳ USB2.0 VGA UVC WebCam                     id=11   [slave  keyboard (3)]     ↳ Asus WMI hotkeys                          id=13   [slave  keyboard (3)]     ↳ AT Translated Set 2 keyboard              id=14   [slave  keyboard (3)]   Apparently my touchpad's type is not shown in the list. What are the possible solutions to fix this issue? set css border to end in a 90 instead of a 45 degree angle What are the recommended textbooks for introductory calculus? How can I safely move a module to another folder? I created a module through Drupal Console, unfortunately it wasn't placed in a folder of its own, rather straight into /modules/custom. Before I noticed where it had gone, I enabled the module.   In Drupal 6/7, this was easy to fix - I could literally just put the files into the correct path, clear the cache (maybe rebuild the registry, it wasn't an exact science), and all was well.  The same isn't true for Drupal 8; I moved the files into a subfolder, rebuilt cache, and all requests tell me that Drupal is failing to include a required file. The particular file is a block class, and the path Drupal is trying to find it is where it used to be, not where I've moved it to.  The bit of code objecting is in Symfony's ApcClassLoader, so I guess I need to clear something that's slightly above Drupal's head to get this path reference updated.  How can I do that?  Uninstalling and re-installing the module does work, but once there's important data stored that's not going to be an option.  I was wrong, uninstalling and re-installing is not a viable option. After uninstalling and reinstalling, Drupal can no longer pick up the custom blocks the module defines. I'm guessing that reference is cached somewhere that isn't cleared when the module is uninstalled. Just need to find out where that is and how to clear it... Is it possible to access a 64-bit dll from a 32-bit application? What is the difference between Affection and Friendship, if any? I've risen Pokemon Amie Affection to 5 hearts on my Riolo in the hopes that it will evolve as soon as it levels up, but I'm not certain that this is the same thing as friendship, and I'd like to not waste a level.  My question is this: What is the difference between Pokemon Amie Affection and the Friendship stat? How to get correlation between two categorical variable and a categorical variable and continuous variable? I am building a regression model and I need to calculate the below to check for correlations   Correlation between 2 Multi level categorical variables Correlation between a Multi level categorical variable and continuous variable  VIF(variance inflation factor) for a Multi level categorical variables   I believe its wrong to use Pearson correlation coefficient for the above scenarios because Pearson only works for 2 continuous variables.   Please answer the below questions   Which correlation coefficient works best for the above cases ?  VIF calculation only works for continuous data so what is the alternative?  What are the assumptions I need to check before I use the correlation coefficient you suggest?  How to implement them in SAS &amp; R? How To Get Command Blocks Talking in Chat