How do I assign an element in matrix?
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How can I install Broadcom Wireless Adapter BCM4352 802.11ac PCID [14e4:43b1] (rev 03) on fresh install of Ubuntu 14.10 (Utopic Unicorn)? I have a brand new Dell XPS 15. I   dual boot it with Windows 8.1 and  Ubuntu 14.10  The Wireless Network Adapter is Broadcom BCM4352 802.11ac with PCID [14e4:43b1] (rev 03).  The 4352 is not included in the list for installation via bcmwl-kernal-source file. I tried this anyway, but the Terminal command led to the file starting to install, but then stopping. Sometimes I get a permission denied error message.  As a result of reading and trying all advice from forums I have decided to completely reinstall Ubuntu 14.10. I doubt my particular Broadcom Wireless Card has no support on Ubuntu 14.10?    Edit:  The advice of Chili555 worked. I now have working wifi using Broadcom Wireless Adapter BCM4352 802.11ac PCID [14e4:43b1] (rev 03) Simple explanation to the induction from the slowly changing $\vec B$ of a solenoid in the region of $0$ magnetic field GTA V Online Character Transfer PS3 to PS4 How to test if a player is near coordinates in 1.13? Show that SO(n) is a normal subgroup of O(n).  A normal subgroup is a subgroup which is invariant under conjugation by members of the group of which it is a part. SO(n) is the set of orthogonal matrices of determinant 1. O(n) is the set of real matrices whose inverses equal their transposes (orthogonal matrices). I'm simply bad at writing proofs. Please help? I am learning Linux and I was trying the gzip command. I tried it on a folder which has a hierarchy like  Personal/Folder1/file1.amr Personal/Folder2/file2.amr Personal/Folder3/file3.amr Personal/Folder4/file4.amr   I ran     "gzip -r Personal" and now its like  Personal/Folder1/file1.amr.gz Personal/Folder2/file2.amr.gz Personal/Folder3/file3.amr.gz Personal/Folder4/file4.amr.gz   How do I go back? What is the correct way to write 1.5 hours? I'm a bit confused in describing 1.5hrs in words.   Is writing one and a half an hour correct or should it be one and half hour?  E.g:     I'll see you there in one and a half an hour.     OR       I'll see you there in one and half hour.   Or is there any other correct way of writing this? Using OR comparisons with IF statements When using IF statements in Python, you have to do the following to make the "cascade" work correctly.  if job == "mechanic" or job == "tech":         print "awesome" elif job == "tool" or job == "rock":         print "dolt"   Is there a way to make Python accept multiple values when checking for "equals to"? For example,  if job == "mechanic" or "tech":     print "awesome" elif job == "tool" or "rock":     print "dolt" How can I add a new user as sudoer using the command line? After I add a user using adduser, I can't see it via System > Administration > Users and Groups unless I log out and then log in again. Is that normal?  Also, can I set a newly added user as a sudoer or do I have to change that only after adding it? How can I do that via the shell?  Finally, can I delete the original user that was created upon initial installation of Ubuntu, or is this user somehow 'special'? tikz: Distribute evenly and randomly circles I want to fill a part of a picture with more or less evenly and randomly distributed circles which should not overlap. It would be okay if circles are only partly inside the shape.  The density should be like what you see on this page  with values 80-100. (But I do not need so many circles, 30 should be enough, I could repeat the pattern).   I cannot use a grid and "wobble" the circles a bit: The circles are too large and it simply does not look randomly.   Currently I am thinking about a random attempt: Get some random point, measure its distance to existing circles, either paint or throw the point away. Try 100 times and hope that you get the right number of circles (and that it does not take too long). But perhaps someone has a better idea.   The example draws the circles simply manually:  \documentclass{article} \usepackage{tikz} \usetikzlibrary{backgrounds} \begin{document}   \begin{tikzpicture}[framed,gridded,radius=0.5cm]  \draw[red](0,0) rectangle (5,5);   \draw (1,1) circle;   \draw (2.3,1.1) circle ;   \draw (4.5,0.8) circle ;   \draw (5.1,1.8) circle ;   \draw (0.4,3.3) circle ;   \draw (2.1,2.8) circle ;   \draw (3.8,3.5) circle ;   \draw (4.8,4.2) circle ;   \draw (0.8,4.9) circle ;   \draw (2.1,4.1) circle ;   \draw (3.8,2.0) circle ;   \draw (3.5,0.6) circle ;   \draw (3.0,5.0) circle ;      \draw (4.1,5.1) circle ;             \draw (0.9,2.1) circle ;  \end{tikzpicture}  \end{document} It is possible to migrate a question from one Stack Exchange site to another by closing, but if I have a question that I think is on-topic for multiple Stack Exchange sites, is it OK to post it on both (multipost)?   For example, I have a question that's earned me the tumbleweed badge on SO and I'm not sure what the best thing to do with it is. It's about a web server so it might be answerable on Server Fault but it's really more of a programming thing, hence the posting the question on Stack Overflow.    Is there any way to make the question visible on multiple sites (crosspost) and then accept the answer wherever it came from? Do cards with abilities that target trigger heroic? What's the difference between "it excites me" and "that excites me"? I wish to show that $\mathbb{Q}(\sqrt2, \sqrt3)$ is not isomorphic to $\mathbb{Q}(\sqrt[4]2)$.    What I did so far was to show that $\mathbb{Q}(\sqrt2,\sqrt3) =\text{span}\{1,\sqrt2,\sqrt3,\sqrt6\}$.  Assuming they are isomorphic, denoting $f$ the isomorphism, then $f(1) = 1$, so $x^2-3$ has a root in $\mathbb{Q}(\sqrt2,\sqrt3)$ so $\sqrt 3\in\mathbb{Q}(\sqrt[4]2)$. ($\sqrt2 \in \mathbb{Q}(\sqrt[4]2)$, $\sqrt[4]2\cdot\sqrt[4]2=\sqrt2)$.   Thus under the assumption, $\mathbb{Q}(\sqrt2, \sqrt3)\subseteq \mathbb{Q}(\sqrt[4]2)$. As a vector spaces of the same dimension over $\mathbb{Q}$, it means that $\mathbb{Q}(\sqrt2, \sqrt3)= \mathbb{Q}(\sqrt[4]2)$.  Now all is left to do it to show a contradiction: $\sqrt[4]2\in\mathbb{Q}(\sqrt2,\sqrt3)$, then $\sqrt[4]2 = a+b\sqrt2+c\sqrt3+d\sqrt6$ so $2=(a+b\sqrt2+c\sqrt3+d\sqrt6)^4$, I believe that opening the expression, I would find out that it can't be an element of $\mathbb{Z}$. However this is a really inelegant way (if it really works), and I wish for a better way to do so.  An other approach: $\mathbb{Q}(\sqrt2,\sqrt3) = \mathbb{Q}(\sqrt2 + \sqrt3)$ by the irreducibility of $x^4-10x^2+1$ over $\mathbb{Q}$ (an some dimension theorem usage). Also, $x^4-10x^2+1$ splits in $\mathbb{Q(\sqrt2, \sqrt3)}$.   Is there a way to show that this polynomial doesn't split over $\mathbb{Q}(\sqrt[2]4)$? with different method then assuming that $\sqrt3\in\mathbb{Q}(\sqrt[4]2)$ and getting a contradiction? Maybe the fact that $\sqrt[4]2$ has complex roots might help? Print two files in two columns I want to print two files in two columns -- first file on the left side and second on the right side. paste doesn't do the job, because it can only insert a character as delimiter, so if first file lines have different length output will be twisted: $ cat file1 looooooooong line line $ cat file2 hello world $ paste file1 file2 looooooooong line   hello line    world  If it was a command to add trailing spaces like fmt --add-spaces --width 50 the problem would be solved: $ paste &lt;(fmt --add-spaces --width 50 file1) file2 looooooooong line                                 hello line                                              world  But I don't know a simple way to do this. So how to merge and print several files horizontally without twisting? Actually, I just want to look at them simultaneously.  UPD: command to add trailing spaces does exist (for example, xargs -d '\n' printf '%-50s\n') But solution like $ paste &lt;(add-trailing-spaces file1) file2  does not work as expected when file1 has fewer lines than file2. Does a Rogue using Use Magic Device for a scroll or wand also need to emulate a class feature? I'm confused about Rogues and Use Magic Device. I've searched the core book and the Internet for the past 4 hours and can't find the answer to my simple question.   Since a Rogue doesn't have any spells, a spell list or caster level, do you have to emulate a class feature in addition to all other necessary checks to use items like scrolls and wands? This button is in the new Firefox, but what is the name of it? How to prove a matrix is nilpotent? Given an $n\times n$ upper triangular matrix $A$ with zero on main diagonal, show that $A^n = 0$.   I did some matrix operation and noticed that the diagonal moves up, ultimately all entries will be zero. Is there a nicer way to do it? Should flawed questions be closed immediately? Possible Duplicate:          Given a question that is not clear at first, which satisfies the criterion for being "not a real question":      "It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot   be reasonably answered in its current form."   should that question be closed immediately, or should the OP get a chance to improve the quality of his question.  My modus operandi is this: When I encounter a question which is "not a real question", I respond via a comment - I might ask one or more counter-questions (about the issue), I might comment that I don't understand the question. So, I let the OP know that his question should be improved. I then give the OP say 15 minutes to respond (and in most cases the OP does respond). However, if the OP doesn't respond, then I consider voting for "not a real question".  Is this how SO should work?   I have witnessed in the past several questions for which I saw potential, being closed immediately, and I wonder if that is appropriate.   Edit: Of course, questions that are duplicates should be closed immediately, and off-topic questions should also be moved / closed immediately. In this question I am specifically referring to those questions which "have potential" (which could be corrected / improved).. $x^p-c$ has no root in a field $F$ if and only if $x^p-c$ is irreducible? Hungerford's book of algebra has exercise $6$ chapter $3$ section $6$ [Probably impossible with the tools at hand.]:     Let $p \in \mathbb{Z}$ be a prime; let $F$ be a field  and let $c \in  F$. Then $x^p - c$ is irreducible in $F[x]$ if and only if $x^p - c$   has no root  in $F$. [Hint: consider two cases: char$(F) = p$ and   char$(F)$ different of $p$.]   I have attempted this a lot. Anyone has an answer?