"An illegal choice has been detected. Please contact the site administrator." When I try to submit the form this validation error is thrown
Resolve the error "An illegal choice has been detected..."
Why do I see a double variable initialized to some value like 21.4 as 21.399999618530273? double r = 11.631; double theta = 21.4;   In the debugger, these are shown as 11.631000000000000 and 21.399999618530273.  How can I avoid this? Site blocked by content filter I run a large and high trafficked WordPress powered platform. One of my editors informed me that our site is blocked at his workspace as a "games site". They use WebCat to filter the traffic.  The issue here is that our platform is not a gaming site, although it does have a games category that covers news. And that is a very minor part of the site.  My question is, what can I do to unblock the site? How does WebCat work? Do they use a universal database to filter the traffic (meaning that the site is blocked on all workspace with WebCat) etc. Obviously they need to improve their filtering algorithm. Casting a function pointer to another type Let's say I have a function that accepts a void (*)(void*) function pointer for use as a callback:  void do_stuff(void (*callback_fp)(void*), void* callback_arg);   Now, if I have a function like this:  void my_callback_function(struct my_struct* arg);   Can I do this safely?  do_stuff((void (*)(void*)) &amp;my_callback_function, NULL);   I've looked at  and I've looked at some C standards which say you can cast to 'compatible function pointers', but I cannot find a definition of what 'compatible function pointer' means. Finding Maximum value of consecutive positive integers with constraints Let, $x,y,z$ be consecutive positive integers such that $\frac{1}{x} + \frac{1}{y} + \frac{1}{z} &gt; \frac{1}{10}$ I need to find the maximum value of $x+y+z$ ?  My attempt:  I tried guessing first, To maximise $x+y+z$ it is necessary to have high value for $x$, But not too high which will contradict the constrain of the problem. As we can roughly split the $0.1$ into three parts so I started with numbers closer to $30$ with trial an error I got that for $x=29$ we get the optimum and final result would be 90 (=max. value of $x+y+z$).   Is there any way to arrive at this conclusion with using inequalities? Any hints will be appreciated... I recently flagged a question as "very low quality", just like I've flagged many questions in the past. However, my flag was found to be unhelpful this time. The same thing happened when I recently flagged a post as not an answer.  Are the moderators being more strict when it comes to handling quality related flags? If so, why? systemctl --user not available for www-data user systemctl --user seems to be working fine for the desktop user:  dev@dev-VirtualBox:~$ systemctl --user &gt; /dev/null dev@dev-VirtualBox:~$ echo $? 0   But when running the same command under the www-data user I get an unexpected response  dev@dev-VirtualBox:~$ sudo su www-data -s /bin/bash www-data@dev-VirtualBox:~$ systemctl --user &gt; /dev/null  Failed to connect to bus: No such file or directory  www-data@dev-VirtualBox:~$ echo $?  1   How to enable systemctl --user here?  Running Ubuntu 16.04 What is the correct way to pluralize an initialism in which the final word is not pluralized by adding the letter "s"? Where does a layman go to get a basic understanding of AKS primality testing. I am not talking about the optimal choice of $r$ (which I am told is the hardcore number-theoretic part of the algorithm). I mean basic things, like what does $\bmod(n, x^r-1)$ mean (how can something be mod two things?) And what does binomial expansion have to do with anything?  I can't find anything in Wikipedia that is appropriate for my level. Counting in a rectangular grid with obstacles I was asked to find the no. of ways to get from (0,0) to (8,8) with the 4 points of the shaded box unpassable, aka I can't use the 4 points namely (3,3)(4,4)(3,4)(4,3) while on my way to (8,8). Right and up movements.  I know it is something like a pascal triangle and worked out the solution of 4050 ways.  May I know if there are any faster means using permutation formula?  Thank you in advance. xcode app crashing on launch with breakpoint How can I execute a file without giving myself execute permissions (with chmod u+x) for it?   If I try and tick the 'Allow executing file as program' checkmark, the checkmark is immediately removed. How to access the grub boot menu in order to generate bootchart? I am running Ubuntu Gnome 15.04, and I want to generate a bootchart to help me diagnose some system problems. However in  it says:    So how do I access the grub boot menu in order to append this text? And just to be clear, how should the line look once I have appended the necessary text? Also, is grub already installed for I don't appear to have either or these packages: grub or grub2?    OS Information:  No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 15.04 Release:    15.04 Codename:   vivid Looking for title/author of SF novel about malevolent creatures/gods residing inside stars Show $f(x)=x\ln x$ is not uniformly continuous Show $f:(0,\infty)\rightarrow \mathbb{R}, f(x)=x\ln x$ on $(0,\infty)$ is not uniformly continuous.    I think that the general way to prove that something is not continuous in a metric space is to let $\epsilon=...$ and show that $\forall\delta&gt;0$, $d&#39;(f(x)-f(y))&gt;\epsilon$. I can't use the Mean Value Theorem because we haven't gone over it yet.    Here's an attempt: Let $\epsilon=1$. Without loss of generality, let $x&gt;y&gt;0$. $|x\ln x-y\ln y|&lt;|(x-y)(\ln x)|\leq|x-y||\ln x|$...$\delta=\frac{\epsilon}{\ln x}$ and therefore doesn't work for all $x$? Can Eigenvalues[] and Eigenvectors[] be assumed to return the same ordering? I'm developing a Custom Post Type plugin, which works fine in dev. Now that I've moved it to production, I'm getting a 404 when I try to display the template for the CPT.   So, two questions:  1- Is there some mechanism to determine the path WP took to get through the hierarchy?  2- Why wouldn't it just give me the single or index page?  I've dumped $wp_query and a stacktrace at the end of the 404. Here's part of what I found:  [query] =&gt; Array     (         [page] =&gt;          [pagename] =&gt; refletters/proximity     )  [request] =&gt; SELECT   wp_posts.* FROM wp_posts  WHERE 1=1  AND (wp_posts.ID = '0') AND wp_posts.post_type = 'page'  ORDER BY wp_posts.post_date DESC  [posts] =&gt; Array     (     )  [queried_object] =&gt;  [queried_object_id] =&gt; 0   And the stack trace:  2013-04-27 22:16:41 - 24.52.197.40 - TRACE - index.php - 404.php[39] -      wordpress/wp-content/themes/notoriousconsultant/404.php[39] - aaLog-&gt;logtrace     wordpress/wp-includes/template-loader.php[50] - include     wordpress/wp-blog-header.php[16] - require_once     wordpress/index.php[17] - require   Thanks for your help. In which Comic Book series is Batman actually Thomas Wayne? I've heard people say that there is a series of comics where Batman is actually Thomas Wayne instead of his son, Bruce.   Where can I find this? What is the series called? In other words, can I do something like  for() {     for {        for {        }     } }   Except N times? In other words, when the method creating the loops is called, it is given some parameter N, and the method would then create N of these loops nested one in another?  Of course, the idea is that there should be an "easy" or "the usual" way of doing it. I already have an idea for a very complicated one. Is it true that the order of $ab$ is always equal to the order of $ba$? How do I prove that if $a$, $b$ are elements of group, then $o(ab) = o(ba)$?   For some reason I end up doing the proof for abelian(ness?), i.e., I assume that the order of $ab$ is $2$ and do the steps that lead me to conclude that $ab=ba$, so the orders must be the same. Is that the right way to do it? How do you set a default value for a MySQL Datetime column?  In SQL Server it's getdate(). What is the equivalant for MySQL? I'm using MySQL 5.x if that is a factor.