I have Ubuntu 18.04 (Bionic) installed on 1 partition (ext 4) using whole disk. I want to downsize it with GParted running from live USB, but after resizing, 18.04 does not boot, showing lots of errors.   I was able to try several times, because I have an ISO image of the system and I recreate it after with Clonezilla.   What should I do?
I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?
Prove that $\frac{1}{\sin^2 z } = \sum\limits_{n= -\infty} ^ {+\infty} \frac{1}{(z-\pi n)^2} $ I no longer use the service that I originally used to register, and would like to change the service I use to log in, or at least add a second account.  Is this possible? How do I change my login provider or associate a backup method to log in?     For more information, see "" in the . Oneboxing a onebox from a different chat server generates a weird URL So if you try to onebox a onebox from a different chat server, . Basically, it generates this URL:    Now, obviously that isn't right. I've also tested this , and I'm assuming it's broken on chat.SO too. Can this be fixed? Why do certain sites require more reputation for privileges? So, let's take Skeptics.SE for an example. You can become a trusted user when you acquire 4000 rep., not 20000  I was like, wow, so is it like this because of the lack of users on Skeptics.Se, as in, not so much as Stack Overflow or something?  Why do some sites need less reputation to be a trusted user? Extra }, or forgotten \right My MWE:  \documentclass{report}  \usepackage{amsmath}  \begin{document}  \begin{align} y &amp;= a \\ =&amp; -2c_1\bar{z}_1^2 + 2\bar{z}_1\bar{z}_2 + 2\bar{z}_2 \left ( -\bar{z}_1 -c_2z_2 - \frac{3\epsilon}{2}\bar{z}_2 -\sigma_{2,1}\cos(x_1)\Delta x_1 \notag \right. \\ \left. &amp;- \sigma_{2,2}\Delta x_2 -\sigma_{2,3} \Delta u +c_2 \chi_2 \vphantom{\frac{1}{1}} \right ) - 2\gamma \sigma_{2,1}^2\cos^2(x_1) \Delta x_1^2 - \gamma \sigma_{2,2}^2 \Delta x_2^2   - 2\gamma \sigma_{2,3}^2 \Delta u^2 \end{align}  \end{document}   The error I get:  Extra }, or forgotten \right.   The expected result: Pre-1972 sci-fi short story or novel: alien(?) tunnel where people try new moves and get destroyed if they're not the correct ones It might be a short story or it might be a novel. It must be before 1972 because I read it in my youth and I am OLD.  The following is very impressionistic.  There is a multidimensional/not of this Earth/alien artifact-like tunnel.   Picture a long, perhaps transparent, storm drain like structure sitting in a field but with an opening on only one end.  It is the subject of a lengthy investigation/exploration that has cost many lives. An instrumented investigator enters the "tunnel" and makes the exact movements that his predecessors have made, advancing until he must do something original at which point he survives and a new "move" is added to the list of correct moves or he is destroyed and a "move" is added to the list of things to be avoided at that point.  I remember absolutely nothing else about the work except that (I hope central) feature. I am using QGIS 3.2.0 on a Mac (and also have QGIS 2), and I have a fishnet grid (probably created in Arc) that comprises of nearly 2 million grid cells. As a result, every change I make to the attribute table takes hours, so I can't experiment as I would usually.  I need to label each grid cell such that the north-westernmost cell is "1", and the numbers proceed by rows, until the last number goes into the south-easternmost cell. Using the row-number doesn't work, as that's not how the table is sorted. I've done this before, but cannot remember how. Lag compensation with networked 2D games I want to make a 2D game that is basically a physics driven sandbox / activity game. There is something I really do not understand though. From research, it seems like updates from the server should only be about every 100ms. I can see how this works for a player since they can just concurrently simulate physics and do lag compensation through interpolation.  What I do not understand is how this works for updates from other players. If clients only get notified of player positions every 100ms, I do not see how that works because a lot can happen in 100ms. The player could have changed direction twice or so in that time. I was wondering if anyone would have some insight on this issue.  Basically how does this work for shooting and stuff like that?  Thanks Prove $[\sin x]' = \cos x$ without using $\lim\limits_{x\to 0}\frac{\sin x}{x} = 1$ I came across this question:   From the comments, Joren said:     L'Hopital Rule is easiest: $\displaystyle\lim_{x\to 0}\sin x = 0$ and $\displaystyle\lim_{x\to 0} = 0$, so $\displaystyle\lim_{x\to 0}\frac{\sin x}{x} = \lim_{x\to 0}\frac{\cos x}{1} = 1$.   Which Ilya readly answered:     I'm extremely curious how will you prove then that $[\sin x]' = \cos x$   My question:  is there a way of proving that $[\sin x]' = \cos x$ without using the limit $\displaystyle\lim_{x\to 0}\frac{\sin x}{x} = 1$. Also, without using anything else $E$ such that, the proof of $E$ uses the limit or $[\sin x]' = \cos x$.    All I want is to be able to use L'Hopital in $\displaystyle\lim_{x\to 0}\frac{\sin x}{x}$. And for this, $[\sin x]'$ has to be evaluated first.    Alright... the definition that some requested.   Def of sine and cosine: Have a unit circumference in the center of cartesian coordinates. Take a dot that belongs to the circumference. Your dot is $(x, y)$. It relates to the angle this way: $(\cos\theta, \sin\theta)$, such that if $\theta = 0$ then your dot is $(1, 0)$.  Basically, its a geometrical one. Feel free to use trigonometric identities as you want. They are all provable from geometry. It looks as if the 10k-tools flagged post list is b0rken.  Next to the review link in the toolbar there is a flag counter showing there are 10 flags to be reviewed:    Clicking on that flag counter leads to an empty page:        The moment I visit that page (through clicking on the flags counter, or by going to the review queue first then clicking on Tools, selecting the flags tab if not already selected), the flags counter disappears from the toolbar:    but after a while (half an hour, an hour?) the flag count re-appears in the toolbar.  Either the counter is wrong (presumably taken from a Redis cache somewhere) or the 10k flag review page is falling over every time someone tries to load it.  This at first appeared to happen only on Meta, on Stack Overflow the flags page has plenty to review. However, there are now  on Stack Overflow. Number of connected components of the complement of a compact Let $X$ be a connected, locally compact space and let $K$ be a compact subset of $X$. Is the number of connected components of the complement $X\setminus K$ finite? If it is not, are there some hypotheses over $X$ for finiteness of connected components? Are all stormtroopers as poor soldiers as the ones in the movies? In the Star Wars films we consistently witness just how poor soldiers stormtroopers are. They show very sub-par marksmanship, crappy house searching tactics, and are easily fooled and defeated by Ewoks and Rebels.   That being said, I remember reading a character guide that defined stormtroopers as the very best of the best (best marksman, above average intelligence, etc.). So, in the realm of the Expanded Universe, does the mold that the movies set continue to hold true or are they just the exceptions to the rule? What are all the common undefined behaviours that a C++ programmer should know about?  Say, like:  a[i] = i++; Where is the Layers panel in Blender 2.8? Why is ++i is l-value and i++ not? When should I use "a" versus "an" in front of a word beginning with the letter h? Learning Regular Expressions I don't really understand regular expressions.  Can you explain them to me in an easy-to-follow manner?  If there are any online tools or books, could you also link to them? Everywhere I get to read statements like EM radiations and EM fields carry "energy as well as momentum " . I wonder if energy and momentum are inalienable . Is it possible for a field to carry only energy without having any momentum term ? I mean isn't it sufficient to say that fields or EM waves carry energy or Doesn't the ability to transfer energy, of the fields, automatically imply that they can change the momentum of another particle while transferring energy to them? Does the integral $\int_{1}^{\infty} \sin(x\log x) \,\mathrm{d}x$ converge? Trigger a button click with JavaScript on the Enter key in a text box I have one text input and one button (see below). How can I use JavaScript to trigger the button's click event when the Enter key is pressed inside the text box?  There is already a different submit button on my current page, so I can't simply make the button a submit button. And, I only want the Enter key to click this specific button if it is pressed from within this one text box, nothing else.  &lt;input type="text" id="txtSearch" /&gt; &lt;input type="button" id="btnSearch" value="Search" onclick="doSomething();" /&gt;