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distance between a line and a point vector formula The Sharpshooter feat includes an interesting feature: you can choose to take -5 penalty to hit with a ranged weapon attack to increase its damage by 10. Normally, I'd dismiss the trade-off as too situational, but I've only just thought of combining it with the Archery fighting style (+2 to hit with ranged weapon attacks).  After building a sample character using these features, the end result looks quite effective. My questions are: Is this build valid? Have I interpreted the rules correctly? If so, how well does it compare against other damage-focused builds?  5th level variant Human Fighter:   Ability Scores (via point buy): Str 10, Dex 16, Con 16, Int 9, Wis 12, Cha 10 HP: 47, AC: 17 (or 18 with disadvantage on Stealth) Weapons: Hand Crossbow x 2 Fighting Style: Archery Martial Archetype: Battle Master (with the Precision Attack maneuver) Feat (variant Human): Crossbow Expert Feat (4th level ability score improvement): Sharpshooter   The end result is a fighter capable of hitting targets 120' away, behind 1/2 or 3/4 cover, or engaged in melee with him, all without penalty. Normally, he can make 3 such attacks per round (Attack action + Extra Attack + Crossbow Expert's bonus attack). Once per short rest he can make 5 attacks per round via Action Surge (Attack action 1 + Extra Attack, Attack action 2 + Extra Attack, Crossbow Expert's bonus attack).  His normal attack bonus is +8 (3 proficiency, 3 Dexterity, 2 Archery fighting style), and normal damage is 1d6+3. Not amazing damage, but nice accuracy and flexibility (attacks can be focused on one target, or spread around; works equally well in melee and ranged combat).  The real winner is his ability to take -5 on any of these attack rolls to increase the damage by 10, to an average of 16.5 per shot (excluding crits). If he lands his usual 3 attacks, that's ~47 damage; 5 attacks is ~83. While the -5 to hit seems imposing, he's still got superiority dice: he can increase his attack roll by 1d8 after seeing the result, up to 4 times per short rest. And even without the superiority dice, his attack bonus is still an acceptable +3; ok for hitting low AC targets, or those granting advantage on attack rolls (e.g. surprised or prone + adjacent).  With a decent AC, a Fighter's HP, and the Second Wind feature, he can also take a decent amount of damage. He'll also have decent Strength, Dexterity, and Constitution saving throws.  This build seems almost too well rounded. Unlike a blaster, he only requires short rests to recover his big hitters. Unlike a brawler, he can target just about anything on the field at a moment's notice. Have I missed any rules, or overlooked any drawbacks? We found this skull on a beach in southwestern Sweden, and are curious as to what kind of animal it was. How secure is Activation Lock on iOS 7 (and later)? Apple showed this new feature in iOS 7 called Activation Lock, that if you enable "Find My iPhone" on a device that is lost or stolen, a person that finds/gets the iPhone will not be able to wipe it or reset it. I'm curious whether the lock is designed to prevent these avenues to defeat the lock:   Can they completely drain the battery and leave the phone in that state for a couple of months and then try it? Or, can they use any third-party software that can access iPhone from outside the iTunes and wipe it that way? Or, can they simply "jailbreak" it and forget about this Activation Lock?   By what methods can this lock be defeated or bypassed? Here's a screen capture from a site where I can view /site-analytics:    The orange "all posts" curve should be strictly larger than the blue "questions" curve, but they are mistakenly displaying the same data. Is the formula $(\text{ker }A)^\perp=\text{im }A^T$ necessarily true? If $A$ is a $n\times m$ matrix, is the formula $(\text{ker }A)^\perp=\text{im }A^T$ necessarily true?  I'm thinking that rank-nullity would be the simplest and easiest way to prove this, but would applying the definition of linear independence to the components of $(A^T)$ be more illustrative? I'm a bit hung up on this "necessity" issue, and not sure if it has a particular logical meaning in linear algebra. Meaning of syntax $N(\mathbf{y} \mid \mathbf{0}, \mathbf{K})$ (multivariate normal distribution) Is there any pair of 128-bit strings M and K such that AES$_K$(M) = M?  If yes, how do I go about (efficiently) finding such a pair? I'm trying to install a Matlab R2011a launcher for Unity in Ubuntu 12.04. I've tried  (although I know it's for 11.10 and mentions that even 11.10 is an unsupported OS for Matlab R2011a) but without any satisfactory solution.  This is my launcher file, /usr/share/applications/matlab.desktop:  #!/usr/bin/env xdg-open [Desktop Entry] Type=Application Icon=/usr/share/icons/matlab.png Name=MATLAB R2011a Comment=Start MATLAB - The Language of Technical Computing Exec=matlab -desktop Categories=Development;   I open the dash panel and search for "matlab". This launcher is found among applications. I click it, and Matlab's splash screen shows up, but when it disappears the program doesn't start. (I've verified with htop that no matlab-processes are running in the background either.)  If I add  Terminal=true   to the launcher file, the program starts OK, and opens a terminal as well as Matlab. However, both the terminal and Matlab itself show up in the Launcher area, with the Matlab icon, so it looks like I have two Matlab instances running when really it's only one. (Actually, they show up as two different programs, and not just two instances of the same - the icons are independent, not grouped together.)  This is definitely not optimal. I had hoped to create a launcher I can lock to the launcher area, and then that same icon will be the icon for the active Matlab instance when the program is running.  How do I create a launcher for Matlab that works as expected?  Update: I was apparently a bit unclear on my symptoms, I'll try to clarify a little. I've also tried some suggestions from the answers, and further investigated what happens. My current setup (a launcher file with Terminal=true and Exec=matlab -desktop -nosplash &amp;) renders the following behavior:   I open Dash by pressing the Windows key on my laptop, and search for "matlab". It finds the launcher named "MATLAB R2011a". I click it. A terminal window opens, using the icon I referred to in the launcher file. Almost immediately, MATLAB's splash screen also opens, using the same icon (and thus being grouped with the terminal window in the launcher). The splash screen disappears and, so does one of the icons in the launcher. The MATLAB desktop environment opens, using a different version of the icon which is displayed next to the icon for the terminal window (not grouped with it).   I can lock the terminal window's icon to the launcher and successfully start MATLAB by clicking it, but it doesn't feel optimal that I start the program with one icon, and switch to it with another. I've also tried the following:   Exec without the ampersand &amp; in the launcher command, but it didn't make a difference. Executing matlab -nosplash manually from a terminal still shows the splash screen. (What, then, does the nosplash option really do?) In the header of my document I set the maximal author names to 2:  \usepackage[style=authoryear-icomp, maxbibnames=9, maxcitenames=2, backend=biber]{biblatex}   Now, when I cite texts with two authors, LaTeX gives me the following:     (Author_A/ Author_B 2012: 232)   When I have three authors or more, LaTeX makes it:     (Author_A/ Author_B et al. 2012: 232)   But I want LaTeX to just name the first author if there are more than two authors ... like this:     (Author_A et al. 2012: 232)   Any tips on how to achieve this ? dpkg-divert: error: rename involves overwriting `/usr/lib/xorg/protocol.txt' with different file `/usr/lib/xorg/protocol-precise.txt', not allowed I just installed Ubuntu (12.04.4) and I upgraded to 13.10  I have no idea how to fix this :/  $ sudo apt-get install -f  Reading package lists... Done Building dependency tree        Reading state information... Done The following packages will be REMOVED:   xserver-common-lts-saucy 0 upgraded, 0 newly installed, 1 to remove and 2 not upgraded. 1 not fully installed or removed. After this operation, 1,718 kB disk space will be freed. Do you want to continue [Y/n]? y (Reading database ... 175174 files and directories currently installed.) Removing xserver-common-lts-saucy ... Removing 'diversion of /usr/lib/xorg/protocol.txt to /usr/lib/xorg/protocol-precise.txt by xserver-common-lts-saucy' dpkg-divert: error: rename involves overwriting `/usr/lib/xorg/protocol.txt' with   different file `/usr/lib/xorg/protocol-precise.txt', not allowed dpkg: error processing xserver-common-lts-saucy (--remove):  subprocess installed post-removal script returned error exit status 2 Errors were encountered while processing:  xserver-common-lts-saucy E: Sub-process /usr/bin/dpkg returned an error code (1) How can we connect a PHP script to MS Access (.mdb) file?  I tried by including following PHP code:  $db_path = $_SERVER['DOCUMENT_ROOT'] . '\WebUpdate\\' . $file_name . '.mdb'; $cfg_dsn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" . $db_path; $odbcconnect = odbc_connect($cfg_dsn, '', '');   But it failed and I received following error message:   Warning: odbc_connect() [function.odbc-connect]: SQL error: [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified, SQL state IM002 in SQLConnect in C:\web\WebUpdate\index.php on line 41 Android How to use MediaScannerConnection scanFile Blender 2.80 AV Sync missing? I just installed Blender 2.8 and for the life of me I can not find AV Sync anywhere and video editing has become impossible. Is there some new setting I am unaware of? Let $A$ and $B$ be $n\times n$ matrices such that $ABAB=0_{n\times n}$.  Can we conclude that  $BABA$ must be  $0_{n\times n}$?   I fail to give a counterexample when $n=2$， so I guess the answer is "yes" When should we use "can", "could", "will", "would"? Most people say I wish I could, I wish you would.    Can we use I wish I can, I wish you will?    I'd like to know what the main differences between the usage of can/will and could/would are when wishing.  Is it related to the subjunctive? Because one says “I wish I were”, not “I wish I am”, so are would and could the subjunctive forms of can and will?  Or is it something else entirely? I have just had my broadband upgraded to  which means my router has had to change. Previously I was using a Thomson TG585v7 ADSL thingy provided by my ISP. One nice thing about that router was that it would act as a local DNS and allow me to find my other machines on the network by using &lt;hostname&gt;.lan instead of IP addresses.  I've now switched to a Linksys WRT320N ethernet router which connects to my fibre modem, and which I've updated to the latest firmware (1.0.04). I have 2 machines on the network which I regularly want to connect to each other; one is running Windows 7 and the other is running OS X Lion.  The problem I'm having is that I'm unable to connect to my Win7 machine from the OS X machine using the Win7 machine's name. However, I'm able to ping the OS X machine from my Win7 machine using the hostname. If I take the $k \in \mathbb{N}$ power of 10 and mod it by a large prime, I notice that the remainders repeat at some point.  For instance $10^k mod~7$ seems to repeat every $8$th value of $k$.  Given $k$ (the power of ten), and a large prime number $p$, how can I compute the size of the cycle?  I tried writing a python script that computes the first instance of a repeat. However, I don't know if this works since a single instance of a repeat may not necessarily mean a full cycle. I want to use a Java file SaveProp which is written in a package user. The class file has been placed in WEBINF/classes. Below are the two lines which cause the issue.  jsp:useBean id="user" class="user.SaveProp" scope="session"  jsp:setProperty name="user" property="*"   It throws:  The value for the useBean class attribute user.SaveProp is invalid   I'm using Tomcat 6.0. missing $ inserted error for equation I get the missing $ inserted error for the following code:  \begin{equation}  C = $ \frac{2}{\omega^2N^2\mu\pia} $  \end{equation}   I have tried out different changes based on Googling for this error, but nothing seems to help. Any suggestions would be appreciated.