Should I defragment my SSD on Windows 7?
Should I defragment my SSD?
Can a shadow move faster than the speed of light? what is the general definition for some partial differential equation being called elliptic, parabolic or hyperbolic - in particular, if the PDE is nonlinear and above second-order.  So far, I have not found any precise definition in literature. Combining two expressions (Expression>) I'm looking for ways to speed up the combat in my D&amp;D 3.5 game. It seems that turns - both player and non-player - simply take too long. I have thought about giving everyone a 30 second timer, but I'm afraid that might inhibit their ability to come up with strategy and tactics. If I've got a file (or files) selected in Windows Explorer, the only way I've found to "unselect" them is click with the mouse on some empty space.  I thought Esc would do this, but it doesn't. Also changing focus with Tab or Shift + Tab doesn't work; the file(s) are still selected even if focus goes to the address bar for instance.  Does anyone know of a keyboard shortcut to do this? In GKP's Concrete Mathematics, there is a useful and interesting feature I would like to see in more books. The bibliography entries include:   a - the page numbers where the book or article is cited in the document. b - a few lines of review of the cited work.   It is a kind of mix between bibliography, index and review.  Are there stable LaTeX packages/BibTeX styles to do (a) and (b) ?  EDIT: I wrote (b) initially as "comments about the work cited". It could be understood as "gathering comments made in the book about the work and reproducing them in the bibliography".  This is not what I meant but this could be something useful for others. Is this a grammatically correct line in a poem: “Will he roll the dice, and follow it to Vegas?”? I want to use the following line in a poem: "Will he roll the dice, and follow it to Vegas?"   A couple of things to note; firstly, obviously I'm using "roll the dice" in both a figurative/idiomatic sense (as in taking a risk), and in a somewhat more literal sense (painting the image of the person actually following the dice that have been rolled to Las Vegas). That being said, my confusion here is if I can get away with using "follow it" or if I need to say "follow them" .... As I've read online "dice" traditionally refers to more than one die (i.e., the plural of die), but in the modern usage, "dice" can also be used to refer to the singular (i.e., just one die).   So, it seems like if I was referring to the image of just one die, then the way I phrased it could be correct. However, the image I'm trying to paint is the one usually associated with the phrase "roll the dice" (i.e., rolling two dice)...   So could "follow it" still be considered acceptable in this sense... or would I need to use "follow them"?... And if not referring to the dice themselves, could using, could the "it" be taken to refer to the act of rolling the dice, or would that not work either? Thanks so much in advance!! How to prove $\cos \frac{2\pi }{5}=\frac{-1+\sqrt{5}}{4}$? I would like to find the apothem of a regular pentagon. It follows from   $$\cos \dfrac{2\pi }{5}=\dfrac{-1+\sqrt{5}}{4}.$$  But how can this be proved (geometrically or trigonometrically)? Looking for the title of a book about alien invasion, mining asteroids and using lasers to defend earth What I remember of this novel/series is that the main character creates solar laser satellites and mines asteroids to create more satellites to defend Earth from aliens. Later on, he uses the hollowed out asteroids as a base and eventually as an armored fortress to repulse the alien fleets. I last remember the main character attempting to hollow out more asteroids to defend and attack the aliens eventually. Increasing the size of the memory: not all files are built successfully I am trying to compile a large file which contains a tikz picture with more data points than tex can handle.  Following the questions  and  I set to increase the capacity of tex by changing the file texmf.cnf in my path /usr/local/texlive/2012. I included the line  main_memory = 10000000   and on terminal I run  sudo fmtutil-sys --all   The problem is that this memory is not enough, and numbers bigger than that don't finish the fmtutil run properly. I get the error   fmtutil: Error! Not all formats have been built successfully.   To give a better idea of where the problem is coming from, if I only include in the file texmf.cnf the lines  main_memory.latex = 15000000 main_memory.pdflatex = 15000000   then these are the files which are not properly built:  This is a summary of all `failed' messages: `pdftex -ini  -jobname=latex -progname=latex -translate-file=cp227.tcx *latex.ini' failed `pdftex -ini  -jobname=pdflatex -progname=pdflatex -translate-file=cp227.tcx *pdflatex.ini' failed   How can I increase the size of the memory beyond 10000000? Am I doing anything wrong?  (BTW, I am running texlive 2012 on a mac) Firefox - Websites with custom fonts not displaying Is there a way to access QGIS plugins in Python?   I'd like to write a script to do some geoprocessing, and I'd like to use the clip, regular points and convex hull tools in fTools, as well as the Road graph plugin. The latter is probably a different can of worms because it is a C++ rather than Python plugin. What is a plain English explanation of "Big O" notation? I'd prefer as little formal definition as possible and simple mathematics. How can I swap Ctrl and Fn keys on a corporate computer? Our computers have been upgraded to HP EliteBook 8570p machines and while they're very nice machines, they are also very large -- so large that the left Ctrl key is too far away, making Ctrl+V really difficult to do with one hand.  I'm sure there are ways to re-map the keys so that their signal is swapped. But add the factor of corporate security, is there still a reasonably simple approach to this?  I'm sure you'd like more information before you can answer -- I'll try to add updates based on comments and answers. Find the inverse of a Trig Matrix I don't have a clue of what's going on. We haven't learn this in class so I need all the help possible. The more detailed of an explanation, the better. Thanks in advance. The only info I have is that this matrix is Orthogonal. Which means I know the answer, just don't know how to get it.  \begin{bmatrix}        \cos\theta &amp; -\sin\theta \\        \sin\theta &amp; \cos\theta       \end{bmatrix} Algebraic extension of perfect field in which every polynomial has a root is algebraically closed Let $F$ be a perfect field, i.e. every irreducible polynomial over $F$ has distinct roots in the algebraic closure of $F$. Suppose that $K$ is an algebraic extension of $F$ with the property that every non-constant $p(X) \in F[X]$ has a root in $K$.   I want to show that $K$ is algebraically closed, i.e. that $K = \overline{F}$, the algebraic closure of $F$.  If $K$ were a normal extension of $F$, this would follow immediately: Let $\alpha \in \overline{F}$ and $m(X)\in F[X]$ its minimal polynomial. By our assumption, $m(X)$ has at least one zero in $K$. Since $K$ is a normal extension of $F$, it thus contains all other roots of $m(X)$ including $\alpha$.  I don't have an idea as to how to show that $K$ is a normal extension. How to measure capacitance without LC meter? I would like to use capacitors salvaged from old electronics, but I currently don't have an LC meter.    What would be some really simple circuits, that would convert capacitance to something I can measure (voltage, current, frequency)? Why is this series of square root of twos equal $\pi$? Wikipedia claims this but only cites an offline proof:  $$\lim_{n\to\infty} 2^n \sqrt{2-\sqrt{2+\cdots+ \sqrt 2}} = \pi$$  for $n$ square roots and one minus sign. The formula is not the "usual" one, like Taylor series or something like that, so I can't easily prove it. I wrote a little script to calculate it and it's clearly visible, but that's not a proof. Let $X, Y$ be an exponentially distributed random variables with parameters $a, b$. Then $X$ has pdf:    $$f_X(x) =\begin{cases} a e^{-a x},&amp; x\geq 0\\ 0,&amp; \text{otherwise}.\end{cases}$$ Suppose $X$ and $Y$ independent. Show that $$\mathbb P(X&gt;Y) = \frac{b}{a+b}.$$   Now I thought the following: $$f(x,y) = f_X(x)\ f_Y(y) = abe^{-ax -by},\qquad\text{for } x,y &gt; 0.$$ And then $$\mathbb P(X&gt;Y) = \int_0^\infty \int_0^x a b e^{-ax -by}\,dydx$$ However, if I solve this (manually or using Wolframalpha), I can't seem to end up with $\frac{b}{a+b}$. Any ideas? "It really doesn't matter" v "It doesn't really matter"