Find row and column index of maximum value in a matrix
Get the row and column name of the minimum element of a matrix
How does Star Trek bridge crew spend their time when on duty? It's implied that the Enterprise bridge crew, in any of the TV series, spend long durations at their duty stations, either sitting or standing.  What exactly are they doing for hours on end while the Enterprise is en route between destinations? Is it me or does this seem like an incredibly tedious if not fatiguing job, sitting in a chair staring at the same view screen? Couldn't these tasks be automated? How to install Chromium without snap? I just discovered that chromium will only be released as a snap package.  How can I continue to get chromium, without snap? Is this possible without building from source?  Notes:   Please let's keep to the question as stated - not "what do you have against snap?" I'm not asking how to remove snap (I realize that would break Ubuntu)... just how to use chromium as it is now, a deb.     Update  No, this is not a duplicate of that linked question. I don't need to know "why it's a snap". I want to know how to use it without snap.  Right now there is building from source, and some random PPA mentioned below. I hope someone can advise us of trustworthy alternatives. How long can I stay in the UK during a 1-year period? I am a Chinese citizen holding a HK SAR passport. How long am I able to visit the UK within a 365-day period?  My stamp is for 6 months. Could I leave within 6 months but re-enter again a couple of weeks for another 6 months? Reading about  I understood that black holes lose energy over time - which is logical in some way (otherwise they would be there forever and heat death would never technically happen)  But - how exactly does it "evaporate"? What happens when it no longer contains enough mass within it's  ? Does it explode somehow? Transforms into "regular matter"? Simply vanishes over time? Or? How do I convince gdal2tiles to output pngs with transparency? Center image element in parent div We know that $e^{\pi i} = -1$ because of de Moivre's formula. ($e^{\pi i} = \cos \pi + i\sin \pi = -1).$  Suppose we square both sides and get $e^{2\pi i} = 1$(which you also get from de Moivre's formula), then shouldn't $2\pi i=0$? What am I missing here? c++ get registry key returns only one char Compare two objects in Java with possible null values When I try to bring down the Achievements tab in Area 51, it's showing an error dialogue.  Strangely enough, the global inbox dropdown works just fine.  Could be connected to .  Screenshot: Calling acro first use when plural is producing an 's' in the short definition that is wrong I have an acro first use that must be plural, but I am getting an erroneous "s" when I shouldn't be. I'm getting (sIMFs) when it should be (IMFs). See picture and code below. The problem only occurs on the first call and it does so for all my acronyms. Thanks in advance.   \documentclass[12pt,twoside]{report} \usepackage{acro} \DeclareAcronym{IMF}{     short = IMF,     long  = Intrinsic Mode Function,     class = abbrev}  \begin{document} \acp{IMF} \acresetall \ac{IMF} \acp{IMF} \acfp{IMF} \end{document} (Note that I have used bold text frequently simply to highlight the key points of my question for those who do not have the time to read through it thoroughly (it is not very long, however); I hope this is not considered offensive.)  There are many textbooks on multivariable calculus. However, some textbooks on multivariable calculus do not focus very much on the theoretical foundations of the subject. For example, a textbook might state a result along the lines of "the order of partial differentiation is immaterial" without proof and ask the student to use this rule to solve problems. Similarly, theorems such as those due to Green and Stokes are often not proved in their full generality.   Therefore, I ask the following question:      What are some good theoretical   multivariable calculus textbooks?   Since "theoretical" is somewhat ambiguous, let me state the following criteria which I would like a "theoretical" textbook on multivariable calculus to satisfy:   The textbook should be rigorous and it should not state a theorem without proof if the theorem is proved in at least one other multivariable calculus textbook. (Of course, the textbook may omit certain theorems; however, this criterion at least ensures that major theorems in multivariable calculus are not stated without proof and used purely for the sake of computations. Also, this criterion permits the textbook to state an interesting theorem if it is beyond the scope of all multivariable calculus textbooks.) The textbook should be primarily based on developing the theoretical foundations of multivariable calculus; therefore, applications such as learning how to compute the partial derivative of a function, learning how to solve extremum problems, learning how to compute etc. should be kept to a minimum. In particular, the textbook can assume that the reader has already seen at least an informal treatment of the subject where these aspects are emphasized. The textbook should have a rigorous treatment of differentiability in $n$-dimensional Euclidean space (e.g., the inverse and implicit function theorems should be proven), Riemann integration in $n$-space, and differential forms (e.g., Stokes theorem should be proven). It would also be a bonus if the book treated the general concept of a manifold. Textbooks with minimal prerequisites are preferred; however, please feel free to suggest books meeting the above criteria even if the prerequisites are quite demanding. Finally, it would also be preferable, but not essential, for the book to only treat multivariable calculus.   Examples of books meeting the above criteria: "Analysis on Manifolds" by James Munkres, "Principles of Mathematical Analysis" by Walter Rudin, and "Calculus on Manifolds" by Michael Spivak.   Although I have studied theoretical multivariable calculus already (four years ago), I could never find "the perfect book" (relative to myself, of course). Every book has its virtues; Rudin for its elegance, Munkres for its beautiful exposition, and Spivak for its "quick and dirty" approach. I am hoping that someone will be able to suggest a book that (relative to myself) is "perfect". Also, this question can be useful to other students who have not yet studied the subject and wish to learn it.   Thank you very much for all answers! Please do feel free to suggest as many books as you can think of so we can form a big list. Also, please try to explain why a particular book is good or at least why you think it is good. I suppose it is fine to suggest a book that is already suggested provided you have a different view as to why the book is good. Since Newton's law of gravitation can be gotten out of Einstein's field equatons as an approximation, I was wondering whether the same applies for the electromagnetic force being the exchange of photons. Is there an equation governing the force from the exchange of photons? Are there any links which would show how the Coulomb force comes out of the equations for photon exchange? I know that my question is somewhat similar to the one posted here , but it doesn't really have an answer to my question specifically. Jutifying: irrational + rational = irrational I'm trying to run multiple Nodejs applications on Nginx server running on CentOS 7. I noticed that when I run a Nodejs app on some ports I get an 502 Bad Gateway error in the browser so I checked the error logs:  [notice] 12806#0: signal process started [crit] 12807#0: *13 connect() to 127.0.0.1:7777 failed (13: Permission denied) while connecting to upstream, client: **.**.99.58, server: myapp.com, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:7777/", host: "myapp.com" [crit] 12807#0: *13 connect() to [::1]:7777 failed (13: Permission denied) while connecting to upstream, client: **.**.99.58, server: myapp.com, request: "GET / HTTP/1.1", upstream: "http://[::1]:7777/", host: "myapp.com"   when I change the app to listen to 8008 for example everything is working fine. I checked permissions and if the process is running as root and everything seems ok. I played with the timeouts as well but no result. Can anyone help? How to check whether a JavaScript variable defined in cross-browser way?  I ran into this problem when writing some JavaScript utilizing FireBug logging. I wrote some code like below:  function profileRun(f) {     // f: functions to be profiled     console.profile(f.constructor);     f();     console.profileEnd(f.constructor); }   It works fine in FireFox/FireBug, but it reports error in IE8 RC1. So, I'd like to do some checking whether console variable exists in the execution environment.  Below code works fine in FireFox, but not in IE8 RC1.   function profileRun(f) {     if (console != undefined) {         console.profile(f.constructor);     }      f();      if (console != undefined) {         console.profileEnd(f.constructor);     } }   However, if I do it this way. It works in IE8 RC1. Why?   function profileRun(f) {     if (window.console != undefined) {         console.profile(f.constructor);     }      f();      if (window.console != undefined) {         console.profileEnd(f.constructor);     } }   Is there any cross-browser way to check it? How do I overload the square-bracket operator in C#? DataGridView, for example, lets you do this:  DataGridView dgv = ...; DataGridViewCell cell = dgv[1,5];   but for the life of me I can't find the documentation on the index/square-bracket operator.  What do they call it?  Where is it implemented?  Can it throw?  How can I do the same thing in my own classes?  ETA: Thanks for all the quick answers.  Briefly: the relevant documentation is under the "Item" property; the way to overload is by declaring a property like public object this[int x, int y]{ get{...}; set{...} }; the indexer for DataGridView does not throw, at least according to the documentation.  It doesn't mention what happens if you supply invalid coordinates.  ETA Again: OK, even though the documentation makes no mention of it (naughty Microsoft!), it turns out that the indexer for DataGridView will in fact throw an ArgumentOutOfRangeException if you supply it with invalid coordinates.  Fair warning. Where to say thanks? Where is the right place to say "thanks" to all those that answered my question? In a comment to my original post, or in a comment to the latest answer or where? In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob] Using math in TikZ