I need to match all alphabetic characters (not only [a-zA-Z], but really all of them including ö, ß, â, ç, Æ, Å, Ĺ, Ĩ, Ÿ, Ș, њ, ѝ, Ц, ت, ר). In other programming languages there is character class named [:alpha:] for this, because it is virtually impossible to name all alpha characters from all alphabets in brackets.  \w doesn't help because it includes digits and underscore. I need letters only without digits, punctuation, spaces.
How can I use Unicode-aware regular expressions in JavaScript?  For example, there should be something akin to \w that can match any code-point in Letters or Marks category (not just the ASCII ones), and hopefully have filters like [[P*]] for punctuation, etc.
Stars and pins are retained when chat messages are moved! In the chat system, stars and pins are retained when moved to another room. This is probably a bug. Here a picture:  When a room owner pins a message, they can move it to another room, and they cannot unpin it. However when a starred message is moved to another room, the user can unstar it in the room it was moved to. Conversation source:  * is irrelevant and does not have to do with this bug report. Many thanks to . Proof: Show there is set of $n+1$ points in $\mathbb{R}^n$ such that distance between any two distinct points is $1$? Javascript function to convert color names to hex codes Context: I want to store the TIFF data to use it for running a linear regression model later on. Ultimate goal: Create a carbon map using field data as a basis. Libraries: library(sp) library(raster) library(tidyverse) library(rgdal)  plotcoord &lt;- SpatialPointsDataFrame(AGCplot[,3:4], AGCplot[,1:2],proj4string=CRS('+proj=longlat'))  pspcoord&lt;-spTransform(plotcoord, CRS('+proj=utm +zone=21')) #Omzetten naar UTM21N (= S1) plot(pspcoord)  s1 &lt;- stack('Some.tif')  colnamen = c(&quot;plotid&quot;,&quot;AGC&quot;,&quot;B2&quot;,&quot;B3&quot;,&quot;B4&quot;,&quot;B5&quot;,&quot;B6&quot;,&quot;B7&quot;,&quot;B8&quot;,&quot;B8A&quot;,&quot;B11&quot;,&quot;B12&quot;,&quot;NDVI&quot;,&quot;NDWI&quot;,&quot;MMRI&quot;,&quot;IRECI&quot;,&quot;MASI&quot;,&quot;VV&quot;,&quot;VH&quot;)  s1_e &lt;- extract(s1,pspcoord,method='bilinear')  Upon extraction I get the following message: Warning message: In proj4string(x) : CRS object has comment, which is lost in output How to show hidden folders in File Manager (Nautilus) on Ubuntu? I've posted a question or an answer, and I have received one or more downvotes. I am not really sure why I was down voted, or I think I know why, but I disagree.  Why did this happen, and what should I do about it? How can I watch Amazon Prime videos using Firefox on Ubuntu 16.04? How can I watch Amazon Prime videos using Firefox on Ubuntu 16.04? Currently Firefox version is 48.0. When I attempt to watch a video, I get the following Digital Rights Error message:  Your web browser is missing a digital rights component. In your web browser’s address bar, type about:addons, press Enter, and then on the left, click Plugins. For the Widevine Content Decryption Module, select Always Activate, and then refresh the video’s page and try watching the video. If the video doesn’t play, go back to Plugins, click the gear icon at the top of the page, and then click Check for Updates. When the plugins have updated, refresh the video’s page, and then try watching the video.  I didn't find Widevine Content Decryption Module. I searched for a solution, but it didn't work... One solution I found was to sudo apt-get install flashplugin-installer and then do the following: sudo apt-add-repository ppa:flexiondotorg/hal-flash sudo apt-get update &amp;&amp; sudo apt-get install libhal1-flash  However, it didn't work and I still got the same Digital Rights Error message. I am able to watch Amazon Prime videos using Google Chrome, but not with Firefox. I want to know if it's possible on Firefox on Ubuntu 16.04. Where are my Minecraft saves located? I want to copy/modify/delete a Minecraft world. Where can I find my saves folder? Prove that, $\frac{a}{b}+\frac{b}{c}+\frac{c}{d}+\frac{d}{a}\ge 4$ where we do not use AM-GM inequality on the given statement to prove it. Extraneous solution from substituting in equations I came across this example of how you could end up with an extraneous solution but I was wondering how it arose. We have the equation: $$x^2+x+1=0 $$ Since x=0 does not satisfy the equation, you can divide by x on both sides which yields: $$x+1+\frac{1}{x}=0$$ which is equivalent to our first equation. From our first eqution we can conclude that: $$-x^2=x+1$$ We now substitute that into the second equation to get:$$x^2=\frac{1}{x}$$ which results in $$x^3=1$$ which is equivalent to our previous equation since x cannot be 0. However, one solution from our last equation is x=1, which is not a solution to our original equation. I have a vague idea that it may have to do with the fact that you get a cubic equation and you began with a quadratic, and that steps imply the following and not vice versa, but can you provide a very detailed answer as to why it arises? Can you please provide more examples? optexp environment error when compiling with XeLaTeX I have troubles with optexp environment. There is a code  \documentclass[pstricks,margin=12pt]{standalone}  \usepackage{pst-optexp}  \begin{document} \begin{pspicture}(3.2,5) \pnodes(0,3){A}(1,3){BS}(3,3){M1}(1,5){M2}(1,1){PD} \psset{mirrortype=extended, mirrordepth=0.2}  \begin{optexp} \beamsplitter[bsstyle=plate, compname=BS](A)(BS)(PD) \mirror[compname=M1](BS)(M1)(BS) \mirror[compname=M2, variable](BS)(M2)(BS) \lens[compname=L](BS)(PD) \optdetector[compname=Det, dettype=diode](BS)(PD) \addtopsstyle{Beam}{beamwidth=0.2, fillstyle=solid,fillcolor=green!20!white} \drawwidebeam(A){BS}{M1}{BS}{M2}{BS}{L}{Det} \end{optexp} \end{pspicture}  \end{document}   and the result is this    and I get "MiKTeX GPL Ghostscript 9.19: Unrecoverable error, exit code 1" error. When I remove optexp environment, so  \documentclass[pstricks,margin=12pt]{standalone}  \usepackage{pst-optexp}  \begin{document} \begin{pspicture}(3.2,5) \pnodes(0,3){A}(1,3){BS}(3,3){M1}(1,5){M2}(1,1){PD} \psset{mirrortype=extended, mirrordepth=0.2}   \beamsplitter[bsstyle=plate, compname=BS](A)(BS)(PD) \mirror[compname=M1](BS)(M1)(BS) \mirror[compname=M2, variable](BS)(M2)(BS) \lens[compname=L](BS)(PD) \optdetector[compname=Det, dettype=diode](BS)(PD) \addtopsstyle{Beam}{beamwidth=0.2, fillstyle=solid,fillcolor=green!20!white} \drawwidebeam(A){BS}{M1}{BS}{M2}{BS}{L}{Det}  \end{pspicture}  \end{document}   the result is     which is correct but optical components are behind beam. I use XeLatex. What am I doing wrong? Which packages are missing? Thank you (example is from manual "Drawing optical experimental setups" where the code works correctly). tcpdump shows traffic until I use a filter I have a server that is receiving traffic from a mirror port on a switch. The interface that is connected to this mirror port is in promisc mode. When I use just a plain catch all tcpdump on the interface, like   tcpdump -nn -i eth1   I see a ton of traffic.  I can even grep this for certain things like, say, port 443.  tcpdump -nn -i eth1 | grep 443   obviously this shows anything that has a 443 in it, not just port 443. I have visually inspected it and I do see stuff like this:  15:08:08.112550 IP 12.34.56.78.1430 &gt; 87.65.43.21.443: . ack 35124 win 32768   But I want just port 443 so...  tcpdump -nn -i eth1 port 443 ... 0 packets captured   Weird. I am not seeing any traffic when I use a filter. I have tried "ip port", "dst port", and a few other filters. I have also tried filtering by the IP instead of port. Nothing.  eth1      Link encap:Ethernet  HWaddr 00:24:81:A5:AD:7A             inet6 addr: fe80::224:81ff:fea5:ad7a/64 Scope:Link           UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1           RX packets:4114781478 errors:0 dropped:1 overruns:0 frame:0           TX packets:17 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            RX bytes:2240970313430 (2.0 TiB)  TX bytes:15155497 (14.4 MiB)           Interrupt:98 Memory:fa000000-fa012800    This interface has seen a ton of traffic. And my filter is valid, right? Why do I not see anything? Question on determinants of matrices changing between integer matrices The following problem came up from a though I had while reading:  Let's say we have $M=\mathbb{Z}^n$ and we have another free $\mathbb{Z}$-module, $N$, inside of $M$ also with rank $n$.  We know we can make a matrix $A$ that changes $N$ to its representation in $M$ (ie has as columns the basis $N$ expressed in coordinates coming from the basis of $M$). If the index of $N$ in $M$ is $m$, I am pretty sure just from tinkering that the determinant of $A$ should also be $m$, however, I have not been able to show this.  It is unclear to me how to proceed. I though maybe I could do something related to the points in $\mathbb{Z}^n$ that are within the unit box of $N$, but I cannot really make sense of this.  Thank you for any help or direction. Understanding Euclid's proof that the number of primes is infinite. In Euclid's proof, if $p_1, p_2, \dots, p_n$ are the only primes then $p_1 \times p_2 \times \dots \times p_n + 1$ is not divisible by any of $p_1, p_2, \dots, p_n$ (because of some algebraic facts), which makes another prime and is a contradiction.   The proof makes sense logically, and I tried some numerical examples to "feel" the proof better but...  $2 \times 3 \times 5\times 7\times 11\times 13+1$ is not a prime! $2 \times 3 \times 5\times 7\times 11\times 13 \times 17+1$ is also not prime! Why is the general case proof is not working for these examples? How to get parent process in .NET in managed way I was looking a lot for method to get parent process in .NET, but found only P/Invoke way. When trying to mount an exfat filesystem, I get the following error:  Error mounting /dev/sda6 at /media/gkp/Backup: Command-line  `mount -t "exfat" -o "uhelper=udisks2,nodev,nosuid" "/dev/sda6" "/media/gkp/Backup"'  exited with non-zero exit status 32: mount: unknown filesystem type 'exfat'   Exfat is used on some USB sticks and camera sd cards. What can I do to mount this type of filesystem? Procedure cache (plan cache) size Is the differentiation operator an open mapping? Consider the vector spaces $C([0, 1])$ and $C^1([0, 1])$ with norm, \begin{align*} \displaystyle \|f\|_\infty=\sup_{x\in [0, 1]}|f(x)|, \end{align*} and let $T:C^1([0, 1])\to C([0, 1])$ the operator given by, \begin{align*} \displaystyle Tf=f'. \end{align*} Is $T$ defined this way an open mapping? If it's, how to prove it? Is Site Traffic Data Gone for Good After Fixing Previous Bug? There was a previous bug affecting site traffic statistics showing -zero- for months (). This has been fixed in that it is now graphing the data.  It appears that previous data may be lost? The graphs below are from . I don't have access to any other sites' graphs to see if they are showing similar results. When I'm sneaking around, I can move more slowly and quietly by holding shift.   But walking this way is really slow. I would like to move a little bit faster, but not full speed.    On a console I imagine you have much finer control over how fast you move with the joysticks. Is there any way to accomplish this on the PC (without an external joystick)?  Perhaps there is a console command or config file setting that will change the % speed modifier that holding down shift uses?