I get the following when trying to install Docker on Ubuntu 16.04:  michael@michael-VirtualBox:~$ sudo apt-get update                     Err:8 https://download.docker.com/linux/ubuntu \ Release                               404  Not Found [IP: 13.32.250.25 443]  Reading package lists... Done                                                         E: The repository 'https://download.docker.com/linux/ubuntu \ Release' does not have a Release file.  N: Updating from such a repository can't be done securely and is therefore disabled by default.  N: See apt-secure(8) manpage for repository creation and user configuration details.   Can someone help me fix this issue?
PPA seems to be constantly offline. Whenever I use sudo apt-get update, this error is shown:  W: Failed to fetch http://ppa.launchpad.net/ 404  Not Found   How do I fix these errors?
How can I model the mechanics of an army battlefield scene? TL;DR;  I want to model a strategic battlefield fight for my players to command and participate. I'm seeking advice on how to model it mechanically so that it is exciting for the players.  Background  The final scene of Act II of my campaign is envisioned to be a big battle between the army of the Big Bad and the allied forces gathered by my players. The full set of Act II runs with the players gaining the allegiance of the different factions to support them on the fight.  Now, in terms of that final scene, I'm struggling to decide how to DM the fight. In games and movies the action is made epic by having cinematic scenes of the fight happening with cuts to our heroes doing their amazing things, be it just plowing through dozens of enemies in quick succession or fighting the big ugly overpowered monster that is otherwise cause havoc among the army. I want that feeling  The set up will involve an army of several thousand enemies agains the different forces gathered by my players. Depending on what they've done during the second act, they'll have more or less support with a minimum number of regiments belonging to several faction (i.e. the silver guard of Wizardwight).  Intended way of DMing the scenario.  What I've come up with is to have the players be military leaders. Draw the map of the battlefield and have them manage the battlefield strategically and tactically, distributing the units and, somehow, enabling a dice based mechanism to evaluate how well each unit is doing. This will transform the tabletop into something similar to Warhammer Fantasy. They can choose to join a particular place of the battlefield to help either together or separately.  I have absolutely no idea on how to model this mechanically (as far as I know D&amp;D 5e does not cover this kind of fights).  Question:  What are good ways to mechanically model this kind of strategic army combat? Should I switch to a different system just for this scene or can I model this with D&amp;D 5e?  Notes on level: At this point I expect my players to range between level 9-12 and for the party to be between 3 and 4 players (this is not a limitation of the campaign, more like the players I'm running the campaign with). Phase shift of 180 degrees of transversal wave on reflection from denser medium Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave, when reflected from an optically denser medium?  I tried searching for it but everywhere the result is just used.The reason behind it is never specified. I'm trying to convert some LaTeX into HTML but my code listings don't preserve their code coloring. Why is that and how do I fix it?  This is what it looks like:    Side note: I'm also wondering why the caption on the table was removed.  Edit  Here is an example listing with colors:  \documentclass{article} \usepackage{color} \usepackage{listings} \lstset{     basicstyle=\footnotesize\ttfamily,     language=[Sharp]C,      keywordstyle=\color[rgb]{0,0,1.0}\bfseries,       commentstyle=\color[rgb]{0.133,0.545,0.133}\bfseries, }  \begin{document} \begin{lstlisting} int x = 10;  // This is a comment string str = "hello"; \end{lstlisting} \end{document}   This produces the following HTML when doing: htlatex myfile.tex:  &lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"     "http://www.w3.org/TR/html4/loose.dtd"&gt;   &lt;html &gt;  &lt;head&gt;&lt;title&gt;&lt;/title&gt;  &lt;meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"&gt;  &lt;meta name="generator" content="TeX4ht (http://www.cse.ohio-state.edu/~gurari/TeX4ht/)"&gt;  &lt;meta name="originator" content="TeX4ht (http://www.cse.ohio-state.edu/~gurari/TeX4ht/)"&gt;  &lt;!-- html --&gt;  &lt;meta name="src" content="LaTeX4.tex"&gt;  &lt;meta name="date" content="2012-07-20 12:30:00"&gt;  &lt;link rel="stylesheet" type="text/css" href="LaTeX4.css"&gt;  &lt;/head&gt;&lt;body  &gt;    &lt;!--l. 12--&gt;    &lt;div class="lstlisting" id="listing-1"&gt;&lt;span class="label"&gt;&lt;a   id="x1-2r1"&gt;&lt;/a&gt;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;int&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;x&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;=&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;10;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;br /&gt;&lt;span class="label"&gt;&lt;a   id="x1-3r2"&gt;&lt;/a&gt;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;br /&gt;&lt;span class="label"&gt;&lt;a   id="x1-4r3"&gt;&lt;/a&gt;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;//&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;This&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;is&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;a&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;comment&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;br /&gt;&lt;span class="label"&gt;&lt;a   id="x1-5r4"&gt;&lt;/a&gt;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;string&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;str&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;=&lt;/span&gt;&lt;span  class="cmtt-8"&gt;&amp;#x00A0;&lt;/span&gt;&lt;span  class="cmtt-8"&gt;"&lt;/span&gt;&lt;span  class="cmtt-8"&gt;hello&lt;/span&gt;&lt;span  class="cmtt-8"&gt;"&lt;/span&gt;&lt;span  class="cmtt-8"&gt;;&lt;/span&gt;     &lt;/div&gt;  &lt;/body&gt;&lt;/html&gt;   Which looks like this:    I would want the HTML result to look like this: What are character special and block special files in a unix system? Open CSV File with Different Delimiter Opposite of Alternatives I'm looking for a more politically correct substitute for the expression "poor man's", meaning an inferior improvised or makeshift substitute. Usage examples:   "Guncotton is the poor man's TNT" "Poor man's oyster" (mussels, or coughed up phlegm)    My hesitance is mainly because it is not as gender neutral as perhaps it once was. The closest I can think of is "pauper's", but I don't know many examples of usage. In MS SQL how do I find out what tables have not been queried or updated in a long time? When do we still need the table and figure environments when we don't want the enclosed objects to float? The LaTeX Wikibook :     Please understand: you do not have to use floating tables. It only   looks more professional. If you want to place your tables where they   lie in your source code, do not use table at all! This is a very   common misunderstanding among newcomers.   LaTeX works with an intricate , but I often prefer immediate placement with the H placement specifier (enabled by the float package).  My understanding is that captions and table/figure numbering require the table/figure environments. Is this really so, or are there ways around that? What other reasons are there for using table/figure if we know that we don't want a particular object to float? Hair particles render not same as 3dView(Eevee) If $\vec{a},\vec{b},\vec{c},\vec{d}$are unit vectors, $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ and $\vec{a}.\vec{c}=\frac{1}{2}$,then If $\vec{a},\vec{b},\vec{c},\vec{d}$are unit vectors such that $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ and $\vec{a}.\vec{c}=\frac{1}{2}$,then $(A)\vec{a},\vec{b},\vec{c}$ are non-coplanar $(B)\vec{a},\vec{b},\vec{d}$ are non-coplanar $(C)\vec{b},\vec{d}$ are non-parallel. $(D)\vec{a},\vec{d}$ are parallel and $\vec{b}$ and $\vec{c}$ are parallel.    My Attempt: $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ $(\vec{a}.\vec{c})(\vec{b}.\vec{d})-(\vec{a}.\vec{d})(\vec{b}.\vec{c})=1$ $\frac{1}{2}(\vec{b}.\vec{d})-(\vec{a}.\vec{d})(\vec{b}.\vec{c})=1$    Book's Solution which i did not understand: $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ is possible only when $|\vec{a}\times\vec{b}|=|\vec{c}\times\vec{d}|=0$ and $(\vec{a}\times\vec{b})$ is parallel to $(\vec{c}\times\vec{d})$ And the correct option given is $(C)$.  I could not solve this problem after some efforts.Please help me.Thanks. A homework question from my algebra class asks:     Show that in a local ring $R$ with maximal ideal $M$, every element outside $M$ is a unit.   My argument is that since $M$ is maximal $R /M $ is a field and so for any $ x \in R \backslash M $, $ x + M $ has a multiplicative inverse, which implies $ x $ is a unit.  I don't see where we need the fact that $R$ is a local ring. Cost increase and suspend "Baggage" versus "luggage" I have the feeling that luggage is more closely associated with vacation travel, whereas baggage is for general transportation.  Or... are they just exact synonyms? A new tab for a record Type! Hello Folks,              I have a question which might be more on the admin side of the force.com platform but involves development.  Question: If I create record types for an object, how can I create separate tabs for the same object but different record types. And, since they all are going to share the same fields, how can I distinguish the labeling?  I dont think this is currently possible, but I would like to know how can it be achieved?  What I have tried: I tried creating visualforce pages with enhanced lists but then in the enhanced list I can not specify the record type.  Please let me know how can I achieve this! Thank you for the help. How to use Stokes theorem in the presence of holes? Does "Going Infinite" necessarily end the game? Find the center of the symmetry group $S_n$. Find the center of the symmetry group $S_n$.   Attempt:  By definition, the center is $Z(S_n) = \{ a \in S_n : ag = ga \forall\  g \in S_n\}$. Then we know the identity $e$ is in $S_n$ since there is always the trivial permutation. Suppose $a$ is in $S_n$, but not equal to identity. Now we can imagine the permutation as bijective function that maps from $\{1,2,\dotsc,n\}$ to $\{1,2,\dotsc,n\}$.  So suppose $p$ is a permutation map. Then $p$ maps from a location $i$ to a location $j$. Take $p(i) = j$ where $i\neq j$. Let $k$ be in $\{1,2,\dotsc,n\}$, where $k$, $i$ and $j$ are all different elements. The cycle $r = (jk)$, then we will see if this commutes.  $rp(i) = rj$    Can someone please help me, I am stuck?  Thank you. How to Fix "Read-only file system" error when I run something as sudo and try to make a folder/file? When I try to save something or rename a file/folder it say this error " Read-only file system" or run something as root in the terminal it say this error  sudo: unable to open /var/lib/sudo/"My User Name"/0: Read-only file system  W: Not using locking for read only lock file /var/lib/dpkg/lock E: Unable to write to /var/cache/apt/   E: The package lists or status file could not be parsed or opened.   When I make a Folder the error dialog in the details with Nautilus is this:    Error creating directory: Read-only file system   I would show you I picture of it but it isn't even letting my save onto my flash drive. Please help me. Money transfer from India to USA My daughter is a US Citizen. We (parents)are also planning to permanently settle in US. We will go their as Permanent Resident,as per US Law. We have a house here in India worth Rs.2 Crores.  We want to sell it and take money with us. We have ordinary savings Bank account here in India.  My US Citizen Daughter is a Income Tax payer.  Now your advises are required as under:   What are the routes to take money from India to US and our tax liabilities Can I gift this whole amount to my US Citizen Daughter or what is the maximum limit of Gift amount.  What will be the tax liability on me and on my Daughter in case of Gift   Whether I have to show it in my Income Tax Return or in my Daughter's Tax Return. What US Income Tax Laws says. What will be the procedure to send money as Gift to my Daughter. Will the money will go directly from my Bank Act.to my Daughter's Bank Account. Will there will be wire transfer from bank to bank Can I send money through other money sender Certified Companies also.    Please advise. If there is something more on the subject to make me understand, please advise. Thanks,