I am getting these errors  W: Failed to fetch http://download.virtualbox.org/virtualbox/debian/dists/utopic/contrib/binary-amd64/Packages  404  Not found  W: Failed to fetch http://download.virtualbox.org/virtualbox/debian/dists/utopic/non-free/binary-amd64/Packages  404  Not found   How do I stop these messages from appearing?
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?
Equation for a smooth staircase function I am looking for a smooth staircase equation $f(h,w,x)$ that is a function of the step height $h$, step width $w$ in the range $x$.   I cannot use the unit step or other similar functions since they are just one step. I have been experimenting with various sigmoid curves and while I can get a single smooth step I cannot get to realize the staircase shape. The closest staircase function I have found is given in  in equation (18) and depicted in Fig. 4 and it is a close example of what I want (i.e generate a staircase in the range $x$ for arbitrary step heights and widths) but it is not smooth at all.  Regarding smooth steps, a likely starting point I found is  but it gives a smooth function of just a single step. I have been unable to modify the equation to make it into a staircase. I would like to specify arbitrary step heights and widths and generate a smooth staircase in the range $x$ specified.    Edit (Extra info): The smooth function I mention above has the problem that the upper, horizontal line is not equal in length to the lower, horizontal line which is why I have been unable to adapt it into a staircase function   Edit 2 Including some pictures     Edit 2 Plot of $s$ with a steep slope showing a different width on the first horizontal line I've found ,  and  which are releated to my question, but no longer seem to apply since Drupal 8.1 and the deprecation of .  Also popular guides such as  appear to no longer apply as they also mention composer manager.   The other solution opposed to composer manager, alter the core composer.json file feels like too much core hacking and would probably break with every Drush update of Drupal core(?).  More specifically, I am attempting to update  from Drupal 7 to 8. I have created my composer.json file as follows:  {   "name": "drupal/views_vcards",   "description": "Allows creation of vCards using the fields provided by the Views module.",   "type": "drupal-module",   "license": "GPL-2.0+",   "homepage": "https://drupal.org/project/views_vcards",   "require": {     "maennchen/zipstream-php": "0.3.*"   } }   But if I put a composer.json file in my module folder, how do I make Drupal aware that that file is there, and how do I make sure the required zipstream-php library is downloaded?  Simply running composer update from the Drupal root does update a lot of Drupal dependencies, but it does not include the composer.json files that are in the modules folders. I also don't assume I should be calling composer install from inside all modules with dependencies.  How do I make Drupal aware of a module's dependency without using composer manager and/or hacking core?  UPDATE:  The  appears to have support a wildcard path:  {     "require": {         "wikimedia/composer-merge-plugin": "dev-master"     },     "extra": {         "merge-plugin": {             "include": [                 "composer.local.json",                 "extensions/*/composer.json" // &lt; ---- THIS LINE             ],             "require": [                 "submodule/composer.json"             ],             "recurse": true,             "replace": false,             "merge-dev": true,             "merge-extra": false         }     } }   Why doesn't core merge modules/*/composer.json, that would solve everything right?  Update 2:  THe reasoning for not supporting this is covered in  (which also has been quiet for some time now). How to run a scheduled job every 15 minutes? Using the salesforce GUI it seams impossible to schedule a job every 15 minutes. Or more than once a day. This is a really weird situation. A guy contacted me regarding a business I have. He offered far in excess of my stated fees and even told me he could help me financially if I needed it, which I do. He said he was a doctor. Before he even showed up, he gave me his bank account and routing number and full name, which I used to pay some utility bills. All the payments went through. He also sent me $2500 through PayPal, and I received an email that I had received the payment, though it's been 24 hours and it still hasn't shown up in my "recent activity" in my account. But at the time when I met him, I had no reason to doubt the whole thing was real.   So we met, and through conversation he seemed totally legit. Halfway through our session, he abruptly left — he claimed he was being called in to the hospital. He had already received some, but not all, of the services we had agreed to. He said he would come back in a few hours. Oh yeah, and since the PayPal funds hadn't gone through yet, and I needed cash to pay rent, he said his "financial advisor" would be wiring me $800 a couple hours later. Well, I never heard back from him and never got a call about a wire transfer. In retrospect it all seems very obviously a scam, except for the fact that he gave me a bank account number that actually worked as far as paying some bills!  My question is, assuming the PayPal payment never goes through — I never got an email saying that it was cancelled, but it isn't showing up in my payments either. I'm planning on calling PayPal if it hasn't gone through by tomorrow. But assuming that payment doesn't go through, how can I use the bank account info to get the payment he promised me as far as the services I provided? Other than paying all my utilities in advance? You'd think with an account number and routing number and full name, I would be able to withdraw money somehow, but I really have no idea how. And since it isn't under my name, I can't make a payment on my student loans. I wouldn't take more than he owed me, but it would really be nice to at least get that, even if I didn't get the $2500 he had promised me.   You always hear about not letting people see your account number and stuff like that, but it seems impossible to do anything with this info even though I have it! If scamming people with their bank account number is so easy, how do scammers do it? So I'm wondering two things:   What legal way can I take what I am owed from this guy? What illegal way do people use this info if they had it? I don't want to get in trouble, but I'm just curious because you always hear how easy it is.   (Oh, and I never actually saw his ID so I don't know that the name &amp; bank info he gave me was actually his, he could have stolen it from someone, though he really didn't seem like a hacker — he was a middle aged black man who was very smart-sounding, polite, soft spoken, and he seemed to have a lot of knowledge that a real doctor would have. I have a college degree and am very skeptical in general and careful about not being scammed and I've never had an experience even close to this, and the whole time I kept thinking "is this guy for real?" but since the utility stuff had gone through, it seemed legit. And nothing he did sent up a red flag like he might be a criminal or something. But later I googled the name and couldn't find a doctor by that name, at least not in the state he said he lives in. And since he said he would be contacting me last night, and he never did, it seems obvious that he planned the whole thing, but it just makes no sense to me.) Did your team win the football match yesterday?         The weather was very bad, so we weren't playing.   vs     The weather was very bad, so we didn't play.   Is the first one not correct? Why is it? Evaluate $\prod \frac {2k - 1} {2k}$ I came across to this: evaluate $$\prod_{k = 1}^{n} \frac {2k - 1} {2k}.$$  I brought it to a closed-form expression in asymptotics but I suspect my asymptotics is bad and I also want to see different solutions, hence the question.  My original solution: Write   $$\begin {eqnarray} \prod_{k = 1}^{n} \frac {2k - 1} {2k} &amp; = &amp; \exp \left (\sum_{k = 1}^{n} \log \left (1 - \frac {1} {2k}\right) \right) \nonumber \\ &amp; = &amp; \exp \left (- \sum_{k = 1}^{n} \sum_{m = 1}^{\infty} \frac {1} {(2k)^m m}\right). \end {eqnarray}$$  Let $$S = \sum_{m = 1}^{\infty} \frac {1} {(2k)^m m} \tag {1}.$$ Multiply both sides of $(1)$ by $2k$ to get $2k S &lt; S + 1$, and by $4k$ to get $4kS &gt; S + 2$. Hence, $$\frac {2} {4k - 1} &lt; S &lt; \frac {1} {2k - 1}.$$ Then, $$\frac {1} {2} \left( \log (4n - 1) - \log 3 \right) - 2 + O \left(\frac {1} {n^2}\right) &lt; \sum_{k = 1}^{n} \sum_{m = 1}^{\infty} \frac {1} {(2k)^m m} &lt; \frac {1} {2} \log (2n - 1) - 1 + O \left(\frac {1} {n^2}\right).$$ Hence, $$\sqrt {\frac {c} {2n - 1}} &lt; \prod_{k = 1}^{n} \frac {2k - 1} {2k} &lt; \sqrt {\frac {3 c^2} {4n - 1}},$$ where $c$ is a constant. Any better approach? An infinite Penney's game. Context: I need to solve one variation of the . Problem: Two players ($A$ and $B$) throw a coin until one of the victory sequences appears. For player $A$ the victory sequence is $HTT$, for player $B$ the victory sequence is $TTH$. What is the probability that $A$ wins and what is the expected number of throws given that $A$ won? My attempt: Intuitively, it seems that player $B$ is more likely to win. Basically, I reliase that we can use the Markov-Chains, but my idea is only draw a binary tree and consider the sequences on the n-th step. My another idea was to calculate the expected number of throws to get, say, $HH$ that would be equal to $r_{HH}$: $$r_{HH} =  \frac{1}{4}E(number|HH) + \frac{1}{4}E(number|HH)+ \frac{1}{4}E(number|TT)+ \frac{1}{4}E(number|TH) = \frac{1}{4}(9 + \frac{5}{2} r_{HH})$$  And get $r_{HH}$. My issues: I don't really understand how to join these ideas to get a proper solution. How to change hair color along length of strand? At some point (not right away), I'll be wanting to make a character model which has multicolor hair.  Namely, it will be one color closer to the roots, and another color closer to the tips.  Is there any way to do this in blender?  I would be using Cycles for this. Feed lists answered questions as "unanswered" Is "I am sat" bad English? I believe it is incorrect and instead either the present continuous     I am sitting   or the predicate adjective     I am seated   should be used.  I hear this quite often, however, and ultimately usage overrules formality.  Does anybody know where this originated or how to describe it grammatically? Showing that $\mathbb{R}$ is connected So I know that $\mathbb{R}$ is both open and closed. But given a set, $X\subset \mathbb{R}$, $X\ne \emptyset $ that is both open and closed, how does one show that $X=\mathbb{R}$?    Here is my attempt: Using the definitions I was given, $X$ open implies that for every $x\in X$ there is a $\delta \gt 0$, $(x-\delta,~ x+\delta)\subset X$.    Also, since $X$ is closed , $B=\mathbb{R}$\  $X$ is open.    However, I don't know how to proceed. NB: This is not a homework problem. I successfully followed  to set different sensitivities for my touchpad and my USB mouse. Only problem is, once you unplug and replug the device or shutdown, restart etc., the settings reset. Is it possible to activate an iPhone 4 without a SIM? So we bought an iPhone 4 from the Apple store. But we didn't get a micro-SIM as there are no PAYG tariffs on micro-SIM available.  Is there anyway to activate the device without getting hold of a SIM? I don't want to sign up to a contract just to develop with. Say I have 12 and have to factorize it in 2 factors. Now possible factors are 1, 12 2, 6 3, 4   Now 3,4 is such that value of maximum factor i.e. 4 is minimized among all pairs.  How to find the solution in generic case where a number N is to be divided in K factors minimizing maximum value. What theorems can I use to prove this? I have a typical scientific manuscript in a LaTeX .tex file, and I need to convert it to MS Word .doc file.  The reason for having to convert to MS Word is I'm submitting the manuscript to an academic journal and they only accept MS Word (I know...)  The manuscript includes title page, figures, tables, equations (inline and in their own align environment), footnotes, bibliography, and an annex.  The tables are in their own separate tables.tex file, which I include using the \include{tables} command.  Most tables take up a whole landscape page, and were generated sing the package pdflscape.  I am using Windows 7 Professional.    My plan is to use pandoc to go from .tex to .odt, open the latter in Libre Office, and convert to .doc.  I have read a related  but it is too general.  Similarly the examples in the Pandoc  are too simple.  I have played around but I am unable to accomplish what I want.  This is surprising since converting a scientific manuscript is probably the most common use case for Pandoc. Here are some sample failures:  Example 1  I open a command line in the project folder, and execute the following:  pandoc -s document.tex -o document.odt   I get this error message:  pandoc: figure1: openFile: does not exist &lt;no such file or directory&gt;   where figure1 is the name of a figure file (e.g. figure1.png) in the project folder referenced in a line as \includegraphics[width=5.8in]{figure1}.  I suspect pandoc expects a .png extension but not sure how to provide it.  Example 2  Next I try .html, and excute the following:  pandoc -s document.tex -o document.html   The program executes fine.  I open HTML file.  Footnotes are there but figures are missing, tables are displayed as LaTeX, bibliography is missing, in-line math displays well, but math in align environment does not, section labels are displayed, and some other minor issues.  So given that mine is probably a typical use case scenario, my question is this: What commands should I use to get the .odt file I want?  I could not find a fully worked out example on the web.    Here is a specific list of errors.  I'll update how I corrected them based on community suggestions:   Figures not rendering.  Solved by adding .png extension to .tex file in \includegraphics command.  Now figures are included but they are huge, with half of each figure outside the page. No bibliography.  Solved. First, I have one huge consolidated Latex .bib file where I keep all my citations.  I manage it using .  This was giving me problems as I do not keep the cleanest .bib file in town.  So I reduced the problem by using a neat trick in JabRef that allows you to subset your master .bib file using the .aux file generated by Latex when compiling your manuscript.  In JabRef click on Tools > New Subdatabase based on AUX file.  This way I generated a much smaller biblio.bib file with only the articles referenced in my manuscript.  Running pandoc -s document.tex -o document.odt --bibliography=biblio.bib did the trick. Display math. Math in \begin{align} environment displayed in verbatim \latex;  (A partial solution is to use the  Libre Office extension.  Copy and paste the latex math code in the .odt file created by Pandoc into the equation editor, and so on.  Surely this could be built into a macro that can post-process all remaining math.)  UPDATE: Display math works very well using --mathjax extension. Inline math. Inline equation do not always render properly.  Bold math is a problem.  E.g. $\Sigma=\sigma^2\bm{I}$ displays as $\Sigma=\sigma^2\bm{I}$; Labels are displayed (e.g. section labels show as [sec:empirical] blah blah]; All tables display as raw latex. What part of speech is handsome in the sentence:     The bridegroom looked so handsome. Getting a vector into a function that expects a vector How do I iterate over a range of numbers defined by variables in Bash? Industry standard file format deliverables for logos?