1-1, onto from [0,1] to (0,1]
How to define a bijection between $(0,1)$ and $(0,1]$?
How to set systemd for automatically force fsck disks after crash (hard poweroff)?  When I used sysvinit (in Arch Linux) as /sbin/init I used the hack: in the rc.local I create /forcefsck file; in the rc.local.shutdown I remove it. At boot-up rc.sysinit enable force fsck if /forcefsck exists.  How to do same in systemd? Maybe it has built-in facilities for automatic fsck after crush? What do the fields in ls -al output mean? Oracle SQL Syntax: Quoted identifier Why does my DIY "solar panel circuit" show battery voltage and not solar panel voltage? Strange black shading. Cannot fully light mesh. (Cycles) Is there a way I can inspect my character's face at any point in the game after creating it during the bathroom scene?  I am playing on PlayStation 4 and rotating with the right stick in 3rd-person view obviously does not show the face. I haven't found any mirrors or shiny objects to use the reflection either.  The reason for this is that I forgot what she looks like and also I want to share my monstrous creation with others but I have already left the vault! Deleted users who created a synonym are listed as "anon" in the tag synonyms list While browsing the  I came across the synonym [vote-to-close] -&gt; [closing] in which the creator is listed as &quot;anon&quot; — the username is not hyperlinked, just like how the user IDs of deleted users are listed in other places like in the list of close voters of a question, etc.  If this really were a deleted user, then I would have expected their user ID to be shown, and not &quot;anon&quot;. So, I checked using  for data on the tag synonym. And sure enough, it shows that the deleted user with the ID 147263 created the synonym. To double-check, I looked up the  and came across a bunch of synonyms created by &quot;anon&quot;. Checking with , these were all created by the now deleted user with the ID 80. Similarly, in the  there are several created by &quot;anon&quot;, but  says that these were created by the now deleted user with the ID 54262.  Feature request: Show the user ID of the tag creator under the &quot;Creator&quot; column in the list of tag synonyms if the user is deleted, to be consistent with how posts and actions by deleted users are attributed everywhere else. I'm studying machine learning and every book I open I bump into chi-squared distribution, gamma-function, t-distribution, Gaussian, etc.   Every book I have opened so far only defines what the distributions are: they don't explain or give the intuition on where the specific formulas for the functions come from.   For example, why is chi-squared distribution the way it is? What is the t-distribution? What is the intuition behind the distribution? Proofs? etc.   I would like to have a clear and fundamental understanding of the most commonly used distributions so that every time later on when I see them, I truly understand what is a t-distribution, what is a Gaussian distribution and most importantly why are they the way they are.   It would be nice if the books / tutorials  can explain the concepts to a layman so that in order to understand them you don't already need to understand them x) Many books are like this, they don't fit for beginners :( Check if specific id element exist Theorem numbering Create tar archive of a directory, except for hidden files? I'm wanting to create a tar archive of a specific directory (with its subdirectories of course). But when I do it, using the tar command, I get a list of files that were included, for example:     a calendar_final/._style.css      a calendar_final/style.css   As you can see, there are two versions of the same file. This goes for every file, and there are many. How do I exclude the temporary files, with the ._ prefix, from the tar archive? Feed can show entries for deleted posts, which viewing them fails Just noticed this:  Someone @replied to me in a question which appropriately showed up in my feed.  I go to click on that notice in the feed, and it presents me with "Loading the question failed."  I'd show a picture, but I don't think that it's entirely relevant - I believe it's reproducible if an answer is posted, someone makes a reply, the answer is removed, then that someone else goes back in the feed to try and revisit the post.  Alternatively, why not synchronize the interface between what a 10K user sees on the site, and what they see in the app?  As a 10K user, I would expect to see deleted questions and answers. Background: I am currently employed by a start-up that, so far, is doing really well. As part of my contract, I have stock options that will come available on a typical vesting schedule. A quarter of my options are set to vest later this year. Also, the company is not public yet, and it may be several years before it is public / I could sell my shares of the company.  My question is, is there any reason I should exercise them as soon as they vest? As far as I know they don't expire as long as I work at my company (if I leave for any reason, then I only have 3 months to exercise).  I don't foresee leaving any-time soon, and if I did, I would have 3 months to make a final decision.  Is there any disadvantage to just letting the option stay an option for a while? How can we disable triggers, Validation Rules and workflow rules in salesforce org. [on off - switch] How can we disable triggers, Validation Rules and workflow rules in salesforce org.  This becomes really needed and important when we are doing data migration(data imports) in salesforce.  The way I handled this is create a custom label and include it in workflow and validation rule logic.   example - Custom label 'Disable workflow' = True then do not fire workflows.            if its False then fire workflow  But wanted to understand if there is any more efficient way to handle these scenarios. Let random vector $x = (x_1,...,x_n)$ follow multivariate normal distribution with mean $m$ and covariance matrix $S$. If $S$ is symmetric and positive definite (which is the usual case) then one can generate random samples from $x$ by first sampling indepently $r_1,...,r_n$ from standard normal and then using formula $m + Lr$, where $L$ is the Cholesky lower factor so that $S=LL^T$ and $r = (r_1,...,r_n)^T$.  What about if one wants samples from singular Gaussian i.e. $S$ is still symmetric but not more positive definite (only positive semi-definite). We can assume also that the variances (diagonal elements of $S$) are strictly positive. Then some elements of $x$ must have linear relationship and the distribution actually lies in lower dimensional space with dimension $&lt;n$, right?  It is obvious that if e.g. $n=2, m = \begin{bmatrix} 0 \\ 0 \end{bmatrix}, S = \begin{bmatrix} 1 &amp; 1 \\ 1 &amp; 1\end{bmatrix}$ then one can generate $x_1 \sim N(0,1)$ and set $x_2=x_1$ since they are fully correlated. However, is there any good methods for generating samples for general case $n&gt;2$? I guess one needs first to be able identify the lower dimensional subspace, then move to that space where one will have valid covariance matrix, then sample from it and finally deduce the values for the linearly dependent variables from this lower-dimensional sample. But what is the best way to that in practice? Can someone point me to books or articles that deal with the topic; I could not find one. Where is the .Trash folder? Proof that disjoint cycles commute The outlet for my range hood was misplaced. It needs to be 4 inches to the side. I can make the junction and move the wiring to the new location but I really don't want to have the empty plate exposed.   The wire is not long enough to reach the required location, so I will make a junction in the existing box, and add a new box at the correct location.  Is there any acceptable circumstance where I could tile over the "old" in-wall junction box?  I'm guessing not, but I figured I'd ask.  EDIT: I should clarify, based on the answers below... I know for a fact that this outlet is the only line on this entire circuit, all the way back to the panel. I am asking explicitly if there is any way to acceptably splice the wiring without exposing a junction box. What kind of lubrication should I use for a lock? I recently made the Yale lock on my front door much easier to open by spraying some WD-40 in there.  However, I just saw  on WD-40 not being a “true” lubricant, and wondered whether it was appropriate to use on Yale locks? Bash copy all files that don't match the given extensions When I import pictures from my camera in Shotwell, it also imports the video clips. This is somewhat annoying, as I would like to store my videos in another folder. I've tried to write a bash command to do this, but have not had success.  I need a command that meets the following requirements:   Locate all files in a directory structure that do not have an extension of .jpg, .png, .gif, or .xcf (case insensitive). Move all of these files into a target directory, regardless of whether the file names or directory paths contain spaces or special characters.   Any help would be appreciated!  EDIT: I'm using the default shell in Ubuntu, meaning that some commands are aliased, etc.  EDIT 2: I've attempted this myself (not the copy part, just the listing of files part). I turned on extglob and ran the following command:  $ ls -R /path | awk '   /:$/&amp;&amp;f{s=$0;f=0}   /:$/&amp;&amp;!f{sub(/:$/,"");s=$0;f=1;next}   NF&amp;&amp;f{ print s"/"$0 }'   This lists everything. I tried using grep on the end of it, but haven't the foggiest idea of how to get it to not match a pattern I give it. The extglob switch didn't help much with grep, even though it does help with other commands.