Create an $f(x)$ that is continuous only at $x = 0$.   In other words, $f(x)$ is discontinuous at every other point. Maybe they are scattered points. However, for $f(x)$ to be continuous at $x = 0$, its limit as $x$ approaches zero must be $f(0)$. But even then, I cannot imagine such a function.  Here is another approach. Consider the function $f(x) = (cx)^n$. If $c$ and $n$ are very large, it acts like two vertical asymptotes squeezing from the sides very near $x = 0$, so that $f(x)$ is continuous only at $x = 0$.  Is my thinking correct? Are there any other ways that we can create such a function?
Possible Duplicate:          I want to know some example of a continuous function which is continuous at exactly one point. We know that $f(x)=\frac{1}{x}$ is continuous everywhere except at $x=0$. But i think this in reverse manner but i dont get any example. So please help me out!
The word "quad" generally means 4. Quadratics don't have 4 of anything. Can anyone explain where the name comes from? Adding a Link to a Field in a Field Set? String queryFields = null;              for(Schema.FieldSetMember field : SObjectType.Task.FieldSets.Activity_Detail_Page.getFields()){                  queryFields = (queryFields == null ? field.getFieldPath() : queryFields+', '+field.getFieldPath());               }                String query = 'Select '+queryFields+' from Task where Id=\''+activityId+'\'';               task = Database.query(query);   i'll creating a field-set,now how do i add link on any field?  above code is  for dynamically query creation . below code of page   &lt;apex:pageBlock title="Activity" id="Block1"&gt;       &lt;apex:pageBlockSection title="Activity Detail"&gt;         &lt;apex:repeat value="{!$ObjectType.Task.FieldSets.Activity_Detail_Page}" var="field"&gt;             &lt;apex:outputField value="{!Task[field.fieldPath]}" /&gt;         &lt;/apex:repeat&gt;     &lt;/apex:pageBlockSection&gt; &lt;/apex:pageBlock&gt;    As per the image attached, I want to add a link in Rounded field that liks to account. Can any one help me? I need your help with references. I have 1 main reference section, and I want to include a second list of references as an appendix. For the main reference I use:  \newpage  \bibliographystyle{plainnat}  \bibliography{library}   The problem is that I don't know how to include the second list using a different bib file, and then calling the function \nocite{*} to show every sources inside the file.   I have the appendix part workout. I need your help to design the function to call the second bibliography, and that does't interfere with the main reference:   \newpage  \appendix  \section{Other Sources} \label{app:ReferencesB}   In addition, I will prefer that the word References is not shown after Other Sources.  Thank you so much!! "Dark L" is "L" at the end of the word or after a vowel sound. Example: ball, pull.  "Light L" is "L" at the beginning or before a vowel sound. Example: light, love.  There are 4 explanations of how to pronounce "dark L":   1st explanation: the tongue tip must contact the ridge right behind the upper teeth. 2nd explanation: before the tongue tip must contact the ridge right behind the upper teeth, you must curl the tongue and make sound like /r/ before make the /l/ as in the 1st explanation. 3rd explanation: just put the tongue between upper and lower teeth is enough to make the dark L 4th explanation: the tongue tip must contact the ridge right behind the upper teeth &amp; the back of the tongue raises up (a British teacher teaches that).   see this vid:  and  for more info  So what is the correct way to make the "dark L"? Call to a member function on a non-object So I'm refactoring my code to implement more OOP.  I set up a class to hold page attributes.  class PageAtrributes  {   private $db_connection;   private $page_title;      public function __construct($db_connection)      {         $this-&gt;db_connection = $db_connection;         $this-&gt;page_title = '';     }      public function get_page_title()     {         return $this-&gt;page_title;     }      public function set_page_title($page_title)     {         $this-&gt;page_title = $page_title;     } }   Later on I call the set_page_title() function like so  function page_properties($objPortal) {         $objPage-&gt;set_page_title($myrow['title']); }   When I do I receive the error message:     Call to a member function set_page_title() on a non-object   So what am I missing? Where in the DNS process are NS records used? I register a new domain, mynewdomain.com, at a hosting company.   In the advanced DNS settings there is an A record which maps mynewdomain.com to a ip address.  In my webhost control panel, it shows me the nameservers for the domain: ns1.mywebhost.net &amp; ns2.mywebhost.net  When I type in mynewdomain.com into a browser and hit enter I believe the following happens.   ISP resolver searches "." nameserver ISP resolver then told to search ".com" nameserver instead. ISP resolver finds mynewdomain.com, and searches the zone file to get the A record.     So my question is, where does my webhost's nameservers come into play? I believe the flaw in my logic comes from the fact that my zone file (in which the A record is kept) is stored on ns1.mywebhost.net). But if that is the case, how does my ISP resolver know to look here? (because I didn't type this into my address bar) In class we are currently covering upper/lower bounds, big Oh and omega and the like. I am pretty good on the "typical" functions one would do, but at a complete loss at "general" statements. This ons function, for example:  $$\forall f\in\mathcal{F}: \lfloor \sqrt{\lfloor f(n)\rfloor }\rfloor \in O(\sqrt{f(n)}).$$  the domain F by the same is all natural numbers that return a real positive number when inputted. My first instinct with something like this is to remove the floors, the general strategy I though to solve this is remove the outer floor, then get rid of the square root, and then the inner floor. But I have no idea how to go about this or if this is even the right way to do it.  Help please? Thanks in advance. $2+2 = 5$? error in proof $$\begin{align} 2+2 &amp;= 4 - \frac92 +\frac92\\ &amp;= \sqrt{\left(4-\frac92\right)^2} +\frac92\\ &amp;= \sqrt{16 -2\times4\times\frac92 +\left(\frac92\right)^2} + \frac92\\ &amp;= \sqrt{16 -36 + \left(\frac92\right)^2} +\frac92\\ &amp;= \sqrt {-20 +\left(\frac92\right)^2} + \frac92\\ &amp;= \sqrt{25-45 +\left(\frac92\right)^2} +\frac92\\ &amp;= \sqrt {5^2 -2\times5\times\frac92 + \left(\frac92\right) ^2} + \frac92\\ &amp;= \sqrt {\left(5-\frac92\right)^2} +\frac92\\ &amp;= 5 + \frac92 - \frac92 \\ &amp;= 5\end{align}$$  Where did I go wrong Why is fundamental group insufficient to classify manifolds? I am trying to count the number of bit-strings of length 8 with 3 consecutive zeros or 4 consecutive ones. I was able to calculate it, but I am overcounting. The correct answer is $147$, I got $148$.  I calculated it as follows:  Number of strings with 3 consecutive zeros = $2^5+5\times2^4 = 112$, because the 3 zeros can start at bit number 1, 2, 3, .., 6  Number of strings with 4 consecutive ones = $2^4+4\times2^3 = 48$, I used the same reasoning.  Now I am trying to count the number of bit-strings that contain both 3 consecutive zeros and 4 consecutive 1s. I reasoned as follows:   the strings can be of the following forms: 0001111x, 000x1111, x0001111..thus there are $2+2+2 = 6$ possibilities for bit-strings where the 3 consecutive zeros come first. Symmetrically there are $6$ bit-strings where the 4 consecutive ones come first.  Thus the answer should be = $112+48-12 = 148$.  clearly there's something wrong with my reasoning, if someone could point it out, that would be awesome. Thanks Setting "checked" for a checkbox with jQuery I'd like to do something like this to tick a checkbox using jQuery:  $(".myCheckBox").checked(true);   or  $(".myCheckBox").selected(true);   Does such a thing exist? What exactly did mv /tmp/folder/* /* do to my filesystem? It's hard to search for special characters on google, which is why I'm posting this here.  I recently ran (as root) a mv /tmp/folder/* /* when I meant to run mv /tmp/folder/* ./ Big mistake!  Things broke! A lot of files got mixed up and placed into strange places, none of the normal unix commands worked (ls, dir, cat, etc) and once you logged off, you couldn't ssh back in -- it would give you a prompt, but not accept the old passwords.  Running ls /* shows me that it performs ls on every directory in /. If I tried to draw a parallel, then mv should have simply moved (or copied?) the files to every directory in /. Instead, really weird things happened, and I was just curious what exactly was going on.  More info: The files in /tmp/folder had been transferred from a windows machine, and had been named file (#).txt, where (#) is a number up to two digits, with a space between file and the parenthesis. There were ~40 of these text files. How do we know Dark Matter isn't simply Neutrinos? Proving $1^3+ 2^3 + \cdots + n^3 = \left(\frac{n(n+1)}{2}\right)^2$ using induction On Windows 10 Professional, with the November update (Build 10586, Version 1511) , is there any possibility to completely remove Windows Defender ?  I don't want to just disable Windows Defender.  I want to completely uninstall from my system. Is there a place where one can leave luggage for more than one day in Brussels? It can be either in the airport or the central station.  I know that there are lockers in the central station. The problem is that these are usually restricted to 24h.  Are there any other services, in Brussels, that take luggage for longer than 24h? How am I supposed to install El Capitan on a new SSD without recovery partition? I have a list of hosts in the network providing shares via SAMBA. How can I determine either IP address or the host name of one particular host, e.g. the one with the name “SASAK02”.  The output of smbtree is as follows  WORKGROUP     \\SASAK02                    \\SAURA-PC1                  \\PC-VAN-DAMME How to estimate $P(x\le0)$ from $n$ samples of $x$? Suppose, we have $n$ samples $x_i$ of a random variable: $$x \sim \mathcal N(\mu,\sigma^2) $$ Based on the samples, we want to estimate the probability that $x$ is negative: $$P(x\le0)$$ Intuitively, I would first estimate: $$\hat \mu=\frac 1 n \sum x_i$$ $$\hat \sigma^2={\frac 1 {n-1} \sum (x_i-\hat \mu)^2}$$ and then calculate: $$P(x\le0)=\frac1{\sqrt{2\pi\hat\sigma^2}} \int_{-\infty}^0 e^\frac{x-\hat\mu}{\hat \sigma} dx$$ However $\hat \mu$ and $\hat \sigma$ have variance! If I use this method, I suspect I am ignoring that variance and making an incorrect estimation. Is this reasoning right? If so, how can I estimate $P(x\le0)$ more correctly, taking $\text {VAR}[\hat \mu]$ and $\text {VAR}[\hat \sigma]$ into account? Why are 15 reputation points required to upvote? I think more reputation points should be required to add a new answer than to upvote an existing answer.  I don't continually watch for new questions, so usually when I find a question it has already been answered.  It seems bit inappropriate to answer an already-answered question in order to contribute to the conversation, but until you earn reputation, you can't upvote or comment; you can only add new answers, which prevents me from contributing at the moment as much as I would like to.  This seems backwards to me. If someone incorrectly upvotes a bad answer, the damage is minimal, as other users can down vote it and upvote the correct answers. On the other hand, an incorrect answer wastes the time of everyone who reads it.  So, IMHO, it should require more reputation points to add an answer than to upvote or comment on an existing answer.  I wouldn't say say that users should be prevented from answering unanswered questions until they have x reputation points, as that might prevent users who have answers from providing them, but perhaps it should be required if the question is already answered, to discourage users from reiterating previously given answers.  What do you think?