Use string substitution to combine array?
How to combine array items with string substitution?
How do I deploy an OpenStack cloud with Juju? I'd like to get a test cloud up and running in preparation for a possible deployment of 12.04. I messed with the UEC a bit, but have had a much harder time finding anything helpful as a primer for the new stack. There is generic documentation on Diablo, but there are likely to be a lot of pieces already handy in Ubuntu that a specific guide could save time with.  Also, as much as I would love to, my budget doesn't include the $4-6k to get a small cluster running with the Canonical support. Early propagation of carries in the BLAKE hash function Limit $\frac{x^2y}{x^4+y^2}$ is found using polar coordinates but it is not supposed to exist. I would like to show that the function $\frac{1}{x}$ is not uniformly continuous on $(0,1)$ using two approaches.   First Approach:   We have the fact that if a function $f$ is uniformly continuous on an open interval $(a,b)$, then the function $f$ is bounded on $(a,b)$. By using its contrapositive, since $\frac{1}{x}$ is not bounded on $(0,1)$, it is not uniformly continuous.  Second Approach:  Proof by definition. Note that the definition of non-uniform continuity is:  There exists an $\epsilon_0&gt;0$ such that for all $\delta&gt;0$, there exists $x,y \in (0,1)$ such that $|x-y|&lt;\delta$ but $|\frac{1}{x} - \frac{1}{y}| \geq \epsilon_0$.  Assume that $\delta &lt; 1$. Let $x = y + \frac{\delta}{2} \in (0,1), y &lt; \frac{\delta}{2} \in (0,1), \epsilon_0 = 1$. Then we have   $$|\frac{1}{x} - \frac{1}{y}| = |\frac{1}{y + \frac{\delta}{2}} - \frac{1}{y}| = \frac{\frac{\delta}{2}}{|y(y + \frac{\delta}{2})|} &gt; \frac{\frac{\delta}{2}}{(\frac{\delta}{2})(\delta)} = \frac{1}{\delta} &gt; 1 = \epsilon_0 $$  If $\delta \geq 1$, then let $\delta^{\prime} = \frac{1}{\delta}$ so that $\delta^{\prime} \leq 1$. The rest proceeds the same as above.   Question: Are my two approaches correct? Starting multiple Chrome full screen instances on multiple monitors from (batch) script My goal is to show different web content full screen on multiple monitors automatically after booting from a single computer. The browser I would like to use is Chrome. If Chrome does not support this and Firefox does that would be fine.  The OS I would prefer is Windows, if it turns out that Linux is possible that would be fine.  On Windows it is possible to set the position of the Chrome browser window (--window-position=) and make Chrome start in full screen mode (--kiosk). Using these options combined you can start Chrome full screen on any of the desktops/screens that you have connected to your computer. I have managed to get this working.  However, if I then try to do the same thing a second time to have Chrome full screen on a second screen the second Chrome window will open over the first window, no matter the coordinates I use for the --window-position parameter.  I have tried using Chrome profiles and copying the Chrome directory and starting the second chrome.exe. All these things result in the same behaviour. I am looking for a book about "advanced" classical mechanics. By advanced I mean a book considering directly Lagrangian and Hamiltonian formulation, and also providing a firm basis in the geometrical consideration related to these to formalism (like tangent bundle, cotangent bundle, 1-form, 2-form, etc.).  I have , but I would like to go into more details about the [symplectic] geometrical and mathematical foundations of classical mechanics.  Additional note: A chapter about relativistic Hamiltonian dynamics would be a good thing. Extra slash added to the chat room URLs in the side bar There is a extra slash added to the chat room URLs in the side bar. This is not causing any redirection issue or 404 not found error. Just observed it and want to notify to the development team about this. Seems it is not a bug, but that can . Currently the following URLs are binded against the chat rooms in the side bar.  Tavern on the Meta https://chat.meta.stackexchange.com//rooms/89  The Fire Department https://chat.meta.stackexchange.com//rooms/1181   GIF for the reference: How to create a generic array in Java? Is "forte" pronounced "fort" or "for-tay"? I've always heard people say something like     "Pronunciation is not my [for-tay]"   ... but I feel that I've heard that the correct pronunciation is     "Confusing people is my [fort]"   What is the proper way to pronounce this word? Shortcut for toggling between different windows of same app? Hyphen or no hyphen when modifying an adjective with a quantity? I have a sentence which has an object that is described with an adjective:     We need to inform our interested patrons of this change.   If I modify "interested" with "more" or "less", do I connect the words with a hyphen or not?  Example sentence:     We need to inform our less-interested patrons of this change.     Also, please let me know if I have not used the correct terms for sentence parts in this question. I need to install a new TeX/LaTeX/ConTeXt package on my computer.  I'm running Ubuntu/Fedora/Slackware/Some-Version-Of Linux.  What are the possible ways to do this?    Note:&nbsp;&nbsp; We get a number of questions that essentially reduce to this one; it was felt a good idea to have one question-and-answer that can cover all the standard methods.  See  for the discussion.  The question-and-answer are CW so that more information can be easily added.  If you have information to add, please do so.  If you are unsure, leave a comment here or (preferably) in .  Comments on the question and answer will be periodically removed to ensure that the information is clear. Is there a definition of  and proper explanation of it?  It is said "Electric charge is the physical property of matter that causes it to experience a force when close to other electrically charged matter."  How is it though that matter can get charged?  Defining charge as the property of feeling a force with other charged matter seems circular.  What is charge?  Is there a non-circular definition / explanation? What is wrong with this fake proof $e^i = 1$? Do I need to change my ESTA address when visiting the US? "std::endl" vs "\n" Many C++ books contain example code like this...  std::cout &lt;&lt; "Test line" &lt;&lt; std::endl;   ...so I've always done that too. But I've seen a lot of code from working developers like this instead:  std::cout &lt;&lt; "Test line\n";   Is there a technical reason to prefer one over the other, or is it just a matter of coding style? Blender for Chromebook How would I be able to run Blender on a Chromebook? The Rollapp is a farce that demands money for free software, and the whole reason I didn't buy a windows laptop is because I hate Windows 10, so is there another option? Do compound subjects like "everyone ... and everyone..." take singular or plural verb agreement? Here are the examples of compound subjects:      Everything on the bed and everything in the closet was organised   in under an hour.   Everybody who witnessed the shooting and everybody   in the room were interviewed.   Anyone on the soccer team and   anybody on the basketball team was eligible for the scholarship.   Should I also use was instead of were in the second example? Or the first and the third examples are incorrect that I should use were instead of was. Is there a way of creating a filesystem object akin to this:  mknod files p cat file1 file2 ... fileN &gt; files   but such that it can be seeked in, as if it were a regular file? Let $S$ and $W$ be subsets of a vector space $V$. Show that if $S$ is a subset of $W$, then $\mathrm{span}(S)$ is a subspace of $\mathrm{span}(W)$ Let $S$ and $W$ be subsets of a vector space $V$. Show that if $S$ is a subset of $W$, then $\mathrm{span}(S)$ is a subspace of $\mathrm{span}(W)$.  Ok I'm finally understanding what each of these things mean.. but I'm running out of ideas on how to actually show it without using arbitrary vector space examples like Rn. Since sets and subspaces are kind of new its hard to figure out how to write correct proofs with them.   I can see how if $V = \mathbb{R}^3$ and $S = \{(1,1,1)\}$ and $W = \{(1,1,1), (1,1,2)\}$ then $\mathrm{span}(S) = R1(line), span(W) = R2(plane)$ and that R1 is a subspace of R2... im just having trouble showing this officially when all vector spaces and sets are completely in general....  I could get as far as writing out $S=(u_1,u_2,\dots,u_n)$, $u_i \in V$ and same with $W$, but I can't really figure out what else to do in this sort of proof.