How does one learn droid binary?
How do people understand astromech droids?
Implement multiple inheritance in Javascript Difference between decimal, float and double in .NET? What is the difference between decimal, float and double in .NET?  When would someone use one of these? Ask question post button remains disabled I've noticed this twice in the last ~2 weeks or so. The &quot;post your question&quot; button can remain disabled for some reason even when your question is shown as &quot;ready to publish&quot;. I.e., you've gotten to the &quot;review&quot; page after the initial edit. If I remember correctly, one case was on Stack Overflow, and the other was on . I'm not sure what exact scenario leads up to this. I haven't paid attention to the button until the last step when I'm ready to click it. The workaround has been to reload the page. (I copied my content for safe-keeping first.) This works, and the button then shows up as active. Afterwards, however, on both occasions, it forced me through the &quot;are you a human&quot; verification.  Update - this question itself did not exhibit this, nor did it do the .  Update - I'm using Chrome on Windows and am not sure what version it was when this happened.  It has  installed, but there aren't any scripts for any Stack Exchange sites.  It has  installed.  The virus scanner on the PC I probably was using was What is the optimal path between $2$ fixed points around an invisible obstructing wall? Every day you walk from point A to point B, which are $3$ miles apart. There is a $50$% chance each walk that there is an invisible wall somewhere strictly between the two points (never at A or B). The wall extends $1$ mile in each direction perpendicular to the line segment (direct path) between A and B, and its position can be at any random location between the two points. That is, it can be any distance between A and B such as $0.1$ miles away from A, $1.5$ miles away, $2.9$ miles away.... You don't know if the wall is present or where it is until you walk into it.  You must walk around the wall if present as there is no other way to circumvent it.  Assume the wall is negligible thickness (like a force field), all ground is perfectly flat, and the y coordinates at both A and B are $0$ (although I don't think the optimal path will change much if they weren't).  What strategy minimizes the average expected walk distance between A and B?  How do we know for certain this strategy yields the shortest average walking distance?  To get the $100$ bounty points, I would like a convincing argument from you as to why you feel your solution is optimal and cannot be beaten.  For those of you using computer simulation, anything reasonably close to optimal is a candidate for the bounty.   Can anyone beat the optimal solutions submitted so far?  There are still a few days to try.  Even a slight beat (if not due to roundoff error or some other error) would help prove previous solutions are non-optimal.  You can just use the table of $31$ points (x-y coordinates) and compute that path length and then if you can find better then I will accept that answer.  I think by Sunday night I may have to award the bounty otherwise it may get auto-awarded. There are 11 letters in the word.   M - 1 I - 4 S - 4 P - 2  so the number of different permutations is $\dfrac{11!}{1! 4 !4!2!}$  Is this correct solution? Why don't the colonists wear spacesuits in Alien: Covenant? In the beginning of the Alien: Covenant movie, a group of colonists from the main ship make a landing on an unknown planet, which they found out accidentally after ship has been bombarded by an unknown wave from a star collapse and what bothers me, is that they don't wear any spacesuits, any protective gear, any air filter systems, just nothing.  Is that really the way future space expeditions gonna explore new possible planets presumed as possible habitable homes for humanity?  Every 5th grader knows, from the biology school lessons, that water, air, and even earth itself contains and gives life to a thousands of viruses, bacteria, and microorganisms.  You can breathe in bacteria, or virus, and be dead in a seconds.  Do film makers really suppose we will take it as realistic depiction of extraterrestrial expedition?   Reality check just screams out loud.  What do you think can be their motivation for such a decision? Is there an implementable (non-theoretical) way to prove if email address belong to real email account? Why was my "shopping list" question closed? My question was closed for being a "shopping list question", even though it was very much related to the topic of the site. Why? Are fractions with prime numerator and denominator dense? At what point does a caster define the target of a spell? The new School of Invention tradition for Wizards () while still in playtesting (and indeed a bit silly in my opinion, more of a "chaos wizard"), got me thinking about its reckless casting ability. This allows the caster to cast magic they do not have prepared and get a random result. The random spells have different targeting criteria (Wall of Stone, Fireball, Feign Death , Mass Cure Wounds) and so it is not possible to decide the target of the spell until it has been cast, as you don't know what you are going to get until it is cast.  This suggests that the designer of the subclass has made the assumption that you don't actually target until you have cast the spell and release it, which makes sense from one point of view, strongly supported by the way a prepared action casting works, PHB p.193 where you cast the spell and hold the energy until the condition is met for the readied action at which point you target the spell.  While the Unearthed Arcana is not RAW or finalized and released, my question is not about this subclass, but about the official rules as a whole.  Is there was any direct RAW, or other supporting or opposing RAW, that states at what point a caster defines the target of a spell?  As a sub-question: are there any circumstances where it actually matters, other than the already defined Readied Action spell casting, in the official rules? Securing SSH server against bruteforcing I have a little SVN server, old dell optiplex running debian. I don't have that high demands on my server, because its just a little SVN server... but do want it to be secure.  I just renewed my server to a newer and better optiplex, and started looking a bit into the old server. I took it down after experiencing problems. When I check the logs, its full of brute-force attempts and somehow someone has succeeded to enter my machine. This person created some extra volume called "knarkgosse" with two dirs "root" and "swap1" or something.  Don't really know why and what they do, but sure do want to prevent this from happening again. I find this a bit strange though because I change my password ever few months or so, and the passwords are always random letters and numbers put together... not easy to brute-force.  I know I can prevent root from logging in, and use sudoers... and change the SSH port, but what more can I do?  So I have a few questions:   How can I prevent logging in for 5 minutes after X amount of incorrect tries. Or slow tries down after each incorrect try? Is there some kind of central blacklist which a server can connect to? A blacklist that keeps track of IP addresses that are "unsafe" and should never be granted access? What more can I do to apply safety to my server?   Like I said earlier, I am running Debian 5 with Apache (www-data user problem?), svn, mysql, php, phpmyadmin, hudson. It is on a home network with port forwarding on 80, 443, 8080, 8180, 23 and 22. In Android, is it possible to block apps from accessing the Internet? Many apps will often connect to remote servers in the background, including Google's own apps or system services. Over time this can eat away at a user's data limit set by a mobile carrier. Does Android allow an app to act as a firewall whereby the user can select which apps have access to the Internet? Or does the device have to be rooted to have that ability? Is there an invalid pthread_t id? I want to know where I can find updated information about all the stable and in-development versions of Ubuntu, where I can find this information?     This question is meant to be a canonical question. It expects to answer the following questions:         Is X version stable yet?   Is X version in beta?   Is X version still supported?   What versions are still supported?   What are the versions in Beta/Alpha?   Until where X version will be supported?   Have X version ceased support?   When will be X version released?   Where I can download any release?   When will the next LTS version of Ubuntu be released?         The list is not exhaustive. How to make 7-zip do a whole bunch of folders Renaming hundreds of files at once for proper sorting I have a ton of files, all named stuff like 1.jpg, 2.jpg, 3.jpg, and so on up to 1439.jpg, however, I have a problem with one of my projects and alphabetizing. It will usually go in the order 1.jpg, 10.jpg, 11.jpg and so on.  What I need is some way to name the files so they are in the format such as 00001.jpg all the way up to 01439.jpg.  How would I be able to do this quickly and efficiently? Show that $\frac{1}{\sqrt{2\pi}} \cdot \left(\int_{- \infty}^{\infty} e^{itx} \cdot e^{-\frac{1}{2}t^2 } dx \right) = e^{-\frac{1}{2}t^2}$ I am struggling to show that $$\frac{1}{\sqrt{2\pi}} \cdot \left(\int_{- \infty}^{\infty} e^{itx} \cdot e^{-\frac{1}{2}x^2 } dx \right) = e^{-\frac{1}{2}t^2}$$  In the same paper we defined  $$F(t):=\left(\int_0^t e^{-x^2}\right)^2 \quad \text{ and} \quad  G(t):=\left( \int _0^1\frac{e^{-t^2(1+x^2)}}{1+x^2} \right)$$  I showed that both functions are differentiable with  $$F'= 2e^{-t^2} \cdot \int_0^t e^{-x^2}$$ $$G' = -2te^{-t^2} \cdot \int_0^1 e^{-x^2t^2}$$  It follows that $F' + G' = 0$ and $F + G = \frac{\pi}{4}$  With that I showed that $\int_{-\infty}^{\infty} e^{-x^2} = \sqrt{\pi}$.  Any help is appreciated. After running a VM and logging out, I got a black screen. I powered off and re-started but got the same after the bios option in start up passed. Several attempts went bye with the same result. So I fiddled with bios boot options a bit and was able to get to a different looking Ubuntu start up screen which, after entering pass key would run a series of commands that were too numerous and frantic to make out. They appeared to be overlapped/layered (the text that is) and seemingly repeating endlessly. I had to power down to get it to stop and re-booting just had the same effect. Finally, I hit the down arrow key when prompted for "disk sda5_crypt" at the pseudo Ubuntu log-in screen I mentioned before. This brought me to an all black screen which read something like:  lvmetad not active cannot process volume group "umbuntu-vg" unlock disk sda5_crypt**   From here I entered a password and Ubuntu start up ran.  That was an unsettling hour or so and I'd like to avoid that in the future. Any ideas what caused it and how to avoid it going forward?  Should have said this before but Ubuntu is the only OS on my machine and my optical drive cannot be opened manually. What does my internet provider know about my online activities? What does my internet service provider know about my online activites in these cases?   plain server (www, ftp, whatever) connection and provider's DNS secured (e.g. TLS) server connection and provider's DNS plain server (www, ftp, whatever) connection and an non-provider non-logging DNS secured (e.g. TLS) server (www, ftp, whatever) connection and non-provider non-logging DNS   In case 4) does my provider know anything more about my online behaviour than "IP w.x.y.z was assigned to Foo Bar between connect-time and disconnect-time" (i.e. only the duration my router was connected)?  What traffic does need to go through the provider's infrastructure to make my connection work at all? TP-LINK TL-WN823N Unable to connect to network I have purchased a TP-LINK TL-WN823N (EU) V2.0 device, which is a USB device that should work as a Network Interface Card, allowing me to connect my computer to wireless networks. Unfortunately, I am unable to find any wireless networks using this device using either wicd or network-manager (no networks appear in the list of networks supplied by either application).  A CD came with the device claiming "Linux support". The CD contained a URL to a corrupted archive file for downloading installation resources. I try to mask my immense frustration.  Here is the additional dmesg output I receive when I connect the device to my computer (similar content is present when I boot the computer with the device connected):  [17096.009912] usb 2-1.2: new high-speed USB device number 4 using ehci-pci [17096.103501] usb 2-1.2: New USB device found, idVendor=2357, idProduct=0109 [17096.103513] usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [17096.103527] usb 2-1.2: Product: 802.11n NIC [17096.103529] usb 2-1.2: Manufacturer: Realtek [17096.103530] usb 2-1.2: SerialNumber: 00e04c000001   This is my lsusb, where the offending device corresponds to Bus 002 Device 004:  Bus 002 Device 003: ID 0a5c:5800 Broadcom Corp. BCM5880 Secure Applications Processor Bus 002 Device 004: ID 2357:0109   Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 004: ID 0c45:6433 Microdia  Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub   As lsusb -v:   It seems the device is working to me, but no new interface is found in 'ifconfig':  docker0   Link encap:Ethernet  HWaddr 02:42:6e:bf:92:16             inet addr:172.17.0.1  Bcast:0.0.0.0  Mask:255.255.0.0           UP BROADCAST MULTICAST  MTU:1500  Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:0            RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)  enp0s31f6 Link encap:Ethernet  HWaddr 30:5a:3a:e1:96:b1             UP BROADCAST MULTICAST  MTU:1500  Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1000            RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)           Interrupt:16 Memory:df200000-df220000   lo        Link encap:Local Loopback             inet addr:127.0.0.1  Mask:255.0.0.0           inet6 addr: ::1/128 Scope:Host           UP LOOPBACK RUNNING  MTU:65536  Metric:1           RX packets:412 errors:0 dropped:0 overruns:0 frame:0           TX packets:412 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:1           RX bytes:31876 (31.8 KB)  TX bytes:31876 (31.8 KB)   Running 'lshw -class network' as root contains only information about the 'enp0s31f6' interface.  Additionally for sanity, my 'uname -a':  Linux home-z170a-ubuntu 4.4.0-22-generic #39=Ubuntu SMP Thu May 5 16:53:32 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux   I am using Ubuntu 16.04.  My questions are:   Why are no networks present in the list for wicd or network-manager? Why is there no additional network interface created when I plug in the USB device? Is it possible to create this network interface?   Thanks for reading.