How to normalize by the covariance matrix?
Bottom to top explanation of the Mahalanobis distance?
How do you make corrections to a published paper? I just heard about the . I'd like to update my firmware, but I don't use Windows/OSX. How can I find out what version of Intel ME I have and how do I update it? Show OPs if someone is answering, live I ask a lot of question on SO, so this recommendation/idea comes from that experience. I'm not really sure how this would fit in with the current structure of SE.   Oftentimes after asking a question, maybe after an hour or so, I end up finding the answer I needed somewhere. And it comes time for me to answer the most difficult question of all: do I delete this question, or do I keep it in case someone answers and others may benefit from it. The problem is, if I don't delete it and no one answers, my acceptance rate goes down. So usually I'll just delete it.  However, sometimes I fear that someone is typing a really really long answer to my question since itäs only been an hour, and so I imagine the nightmare that person experiences when they find out their essay will be gone to waste. Overall, this never-to-be-seen-again answer could have benefitted many people had the question remained.  Since SE has gone "live-happy" lately, where answers and comments refresh live, I thought it might be interesting if the original asker of the question (or anyone else for that matter) could see how many people are currently responding to the question (just count, not necessary to display their names). This way, if I know someone is replying, I won't delete the question, and others can benefit from it. Custom date format with jQuery validation plugin How can I specify a custom date formate to be validated with the  for jQuery? Show $S = f^{-1}(f(S))$ for all subsets $S$ iff $f$ is injective Let $f: A \rightarrow B$ be a function. How can we show that for all subsets $S$ of $A$, $S \subseteq f^{-1}(f(S))$? I think this is a pretty simple problem but I'm new to this so I'm confused.  Also, how can we show that $S = f^{-1}(f(S))$ for all subsets $S$ iff $f$ is injective? Deleting external/auxiliary files? Yes, it's time for me to complain about plagiarism again.  We already have Suggested Edit audits, but I would like to see Tag Wiki and Tag Wiki Excerpt audits that specifically introduce copied content for that tag without including the appropriate source(s), and warn people who approve it that they just approved a tag with plagiarized text.  For example, an audit for the  tag could be:     Microsoft SQL Server is a relational database management system developed by Microsoft. As a database, it is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network (including the Internet). There are at least a dozen different editions of Microsoft SQL Server aimed at different audiences and for different workloads (ranging from small applications that store and retrieve data on the same computer, to millions of users and computers that access huge amounts of data from the Internet at the same time). Its primary query languages are T-SQL and ANSI SQL.   Anyone who spends 15 seconds Googling this will see where it came from -- the problem is, most people don't.  I know with Suggested Edit Audits, it's just random text to catch the most egregious reviewers; for this, you would have to most likely select a small sample of tags, and then create their copy-and-paste entries for audits.    The whole point of this would be to raise awareness for people who have figured out how to recognize and pass Suggested Edit audits, but still don't understand the finer nuances of reviewing. Preview: PDF Highlighting & Search Stop Working until Restart A problem has recently become much more prevalent for me when using Preview to search PDFs for text (using Command + F or the search box in the upper right).  At first, everything generally seems to go fine:    (as it should be) a list of thumbnails appears in the sidebar, indicating all of the pages that contain the search term. Generally, though not always, the term I search for will be highlighted on the first page that it occurs on.   But, after this, things quickly start malfunctioning:   Generally speaking, if I click on thumbnails lower on the list, Preview will take me to that page in the PDF (like it used to).  But, it will no longer highlight the searched for terms. Instead, Preview will make a low-pitched beeping noise of the sort that occurs when one tries to perform some un-permitted action in a variety of mac situations. Furthermore, once this occurs, I cease being able to make any highlights at all in the document I am viewing with Preview.  In fact, I can't even select any text any more.   Below is a list of unsuccessful efforts to resolve this:   Closing the side bar does not work to resolve this. x-ing out the search box in the upper right does not resolve this. Selecting the "Tools" menu and then "Text Selection" does not work either, nor does clicking on the text selection icon in the edit panel. If I quit preview and then re-open the PDF, I am able to highlight again.  But, the problem will re-surface as soon as I try performing another search. Working with the same files in other PDF programs (e.g. Skim, Acrobat, etc.) poses no problems.  I'm quite certain it isn't a problem with the underlying PDFs. None of the responses to  resolve this.  (indeed, I supplied one such response myself a while ago, but that trick and the others no longer work).   I've used Preview for many years without problem.  This issue started cropping up relatively recently for me, I believe within the past 3-4 months.  I had hoped that upgrading to Catalina might resolve it, but it did not.    I'd like to think I am fairly sophisticated with computers (I have a reputation of close to 8,000 on the main stackoverflow page), but I am baffled by this.  I also don't have a good handle on how I can get diagnostic information or how I can create a reproducible example.    Any leads on how to tackle this would be greatly appreciated. Extract substring in Bash Given a filename in the form someletters_12345_moreleters.ext, I want to extract the 5 digits and put them into a variable.  So to emphasize the point, I have a filename with x number of characters then a five digit sequence surrounded by a single underscore on either side then another set of x number of characters.  I want to take the 5 digit number and put that into a variable.  I am very interested in the number of different ways that this can be accomplished. Baking lots of bread - keeping a yeast starter Like many people sheltering-at-home, I'm baking . My yeast supply is running low, and I'm not sure I'll be able to get more on demand. I'd like a simple way to make sure I have yeast on hand for my next batch. Could you all recommend a method for storing a starter culture?  Specifically:   How should I store it (how much? where? I have a fridge ~4C and a wine cooler ~13C)  How often should I feed it? With what? Should I divide the culture when feeding?  How much should I use when baking? Can I treat it like dry active yeast, or does it need more/less time?   For some other context, I'm a novice at making bread (I've made it a few times, and others in my family make it more often). I see lots of advice on sourdough starters, but am interested in something that's a replacement for dry active yeast (unless sourdough starters are actually easier to maintain). I found a  that was similar, but it focused on long-term storage of yeast and the answers did not describe how to use the starter.  Your advice is appreciated. Show reference label when it is undefined So I was thinking... If heat I feel is just lots of particles going wild and transferring their energy to other bodies, why am I not burned by the wind?  When I thought about it more I figured out that wind usually carries some humidity, and since particles of liquid are moving same speed as the wind, they are basically static relative to each other, so no energy is transferred between them (wind and water particles). And if that water sticks to my skin and wind blows, it'll evaporate thus taking energy from my skin and make me feel cold.  Thing is, I don't think that's really the case but even if it is, if I somehow dry out the wind, will it burn me if it's strong enough? And winds can reach some pretty high velocities (though I must admit I'm not sure if they are comparable to movement of atoms in warm bodies etc...).  So. Bottom line. Can I be burned by wind in some perfect scenario? It is said one should avoid staring at Sun as it can damage the eyes, but it is also said that one should not come out in sun during eclipse as it emits dangerous rays. Is that true? If yes, why? "I'm lovin' it" How normal-sounding is the slogan "I'm lovin' it" to native ears?  I know it sounded quite odd to me when I first heard it — and it still sometimes does —, but I can't even tell why. Sure, love is supposedly a stative verb, but it's being used in progressive aspect all the time without sounding weird at all (lots of songs come to mind, e.g. ). It's only this particular slogan that somehow doesn't quite work for me. I would expect that to be totally on purpose — it's advertising, after all —, but Wikipedia  any objections from native speakers (as it does with "" and ""). So I'm asking the native speakers of this community: does "I'm lovin' it" sound completely natural to you? Just a bit off? Completely weird? Why? Why do close votes expire? I nominated  to be closed as a dup. I see that two other people upvoted my comment, so they might have voted to close it as well. Now, we didn't gather enough votes, and all close votes expired ... and I can't re-vote to close. What is the motivation behind expiring close votes ... especially for close-as-duplicate? Update: Please take into consideration:  Beta Stack Exchange sites have a smaller community, and fewer people with voting privileges Closing as a duplicate is &quot;usually the right thing&quot; IMHO - much less controversial than closing as off topic. After a vote is reset, the original users can't vote again. On a small site, this makes it even harder to get a consensus of five votes. Could I use a 1/2TB USB 2/3 external HDD with an XBox 360? I'm considering getting an XBox 360 (plus Kinect). I need storage for other devices as well (movies, PC games, whatever an Ouya might need), so I'm considering getting a big external HDD. Can I store downloaded games (e.g. Fez) on such a device? In the Wikipedia article , it says     After Newtonian gravitation was found to be inconsistent with special relativity, . . .   I don't see how Newtonian gravitation itself is inconsistent with special relativity.  After all, Newton's Universal Law of Gravitation is completley analogous to Coulomb's Law, so it would seem that, if there were an analogous "gravitational magnetic field", one could formulate a theory of gravitation in exact analogy with Maxwell's Theory of Electromagnetism, and of course, this would automatically be consistent with Special Relativity.  What about this approach to gravitation does not work?  The only problem I could see with this is the lack of evidence for a "gravitational magnetic field".  That being said, gravity is "weak" as it is, and my guess is that it would be extremely difficult to set up an experiment in which a massive body were moving fast enough for this "magnetic field effect" to be obsevable.  EDIT:  As has been pointed out to me in the answers, Newton itself is inconsistent with SR.  Similarly, however, so is Coulomb's Law, yet, electromagnetism is still consistent with SR.  Thus, how do we know that it is not the case that Newton's Law is the special "static" case of a more general gravitomagnetic theory exactly analogous to Maxwell's Theory:  Let $\mathbf{G}$ be the gravitation field, let $\rho$ be the mass density, and $\mathbf{J}$ be the mass current density, let $\gamma _0$ be defined so that $\frac{1}{4\pi \gamma _0}=G$, the Universal Gravitation Constant, let $\nu _0$ be defined so that $\frac{1}{\sqrt{\gamma _0\nu _0}}=c$, and suppose there exists a field $\mathbf{M}$, the gravitomagnetic field, so that the following equations hold: $$ \vec{\nabla}\cdot \mathbf{G}=-\frac{\rho}{\gamma _0} $$ $$ \vec{\nabla}\cdot \mathbf{M}=0 $$ $$ \vec{\nabla}\times \mathbf{G}=-\frac{\partial \mathbf{M}}{\partial t} $$ $$ \vec{\nabla}\times \mathbf{M}=\nu _0\mathbf{J}+\gamma _0\nu _0\frac{\partial \mathbf{G}}{\partial t} $$ where theses fields would produce on a mass $m$ moving with velocity $\mathbf{v}$ in our inertial frame the Lorentz force $\mathbf{F}=m\left( \mathbf{G}+\mathbf{v}\times \mathbf{M}\right)$.  This theory would automatically be consistent with SR and would reduce to Newton's Law of Gravitation for the case of gravitostatics:  $\frac{\partial \mathbf{G}}{\partial t}=\frac{\partial \mathbf{M}}{\partial t}=\mathbf{J}=0$.  (To be clear, you can't just set the time derivatives equal to $\mathbf{0}$ as it seems I have done.  Upon doing so, you obtain the corresponding static theory, which is technically incorrect (as you can easily see because it won't be relativistically invariant), but is nevertheless often a useful approximation.)  My question can thus be phrased as:  without appealing directly to GR, what is wrong with this theory? Why is rendered viewport faster than rendering individual frames? When I'm using rendered viewport it initially takes a while before rendering starts, but once it does, I can freely move around and rendering a new view happens almost instantaneously. When on the other hand I'm rendering a movie, for each frame Blender takes a significant amount of time before rendering even starts, usually doing the following:  Synchronizing object, Updating images, Updating meshes, Updating Scene BVH, Packing BVH,  Why does it do this? And is it possible to disable this to increase movie rendering speed? Multiple tables join in SQL for this scenario Consider a text file with the following entries:  aaa bbb ccc ddd eee fff ggg hhh iii   Given a pattern (e.g. fff), I would like to grep the file above to get in the output:  all_lines except (pattern_matching_lines  U (B lines_before) U (A lines_after))   For example, if B = 2 and A = 1, the output with pattern = fff should be:  aaa bbb ccc hhh iii   How can I do this with grep or other command line tools?    Note, when I try:  grep -v 'fff'  -A1 -B2 file.txt   I don't get what I want. I instead get:  aaa bbb ccc ddd eee fff -- -- fff ggg hhh iii