hey let me know why this render goes white when i do final render by pressing f12 ? anyone evert who can solve this matter in 2.81a ?
A scene I made is not rendering, at all. This grey screen stays the same and nothing changes.  Here are my settings:  [
How do I know if an ability is magical? Often confusion arises when the  spell is used, an  is worn, or the 's anti-magic ray is employed, whether a given character's ability will still function.   The spell does give you some guidelines on how to adjudicate the effects of the loss of magic but says very little about how to determine what is affected.  In short, how do I tell if an ability is magical? How to prove that there are finitely many $n$ such that $f(1+1/n) = \frac{1}{n+1}$? Let $f : \mathbb{C} \to \mathbb{C}$ be analytical. How does one prove that there are finitely many positive $n$ such that $f(1+1/n) = \frac{1}{n+1}$ ? A hint is given: think of the expression $\frac{z-1}{z}$.  I think this is a pretty hard homework assignment. Here's what I tried so far: Let $g(z) = \frac{z-1}{z} $ . Then $g(1 + 1/n) = \frac{1 + 1/n - 1}{ 1 + 1/n} = \frac{1/n}{1+1/n} = \frac{1}{n+1} $. So the given hint is probably indeed useful, but I'm not sure yet how.   Another thing I tried to use to obtain the solution was the given fact that $f$ is analytical. Let $f = g$. Then $f(z) = f(x+iy) = \frac{ x + iy - 1}{x+iy} = \frac{x+iy-1}{x+iy} \cdot \frac{x-iy}{x-iy} = \frac{x^2 - 2 i x y + y^2 + iy}{x^2 + y^2} = 1 + i \frac{y(1-2x)}{x^2 + y^2} $ . Now I have written $f$ in the form $ f = u + i v$, with $u,v$ being real-valued functions. So now we can use the Cauchy-Riemann Integral formulas: $ \frac{d}{dx} 1 = 0 = \frac{d}{dy} \frac{ y(1-2x) }{x^2+y^2} \implies \frac{y(1-2x)}{x^2+y^2} = c $. The other formula yields a similar result.   But now what? I still have no idea how to prove that there are finitely many positive $n$ such that the aforementioned equality holds. Should I use any of the results I already obtained? If so, how? If not, do you know how to prove this? Consider this question on .  I put out a 200 bounty on the question, but did not get an answer from anyone other than myself that worked.    In fact, my answer is also the highest up-voted on it at this point.  I know that allowing OP's to retract a bounty can be a slippery slope; in fact I think that once the bounty is put up it should stay up.  But why not allow the OP to answer their own questions with a bounty and reward it to them if they receive the same up-votes as others?  Yes, I am fully aware that bounties are a risk.  People will use them for numerous reasons such as trying to draw extra attention to their issues.  However, in my specific question, the only valid answer is the one that I gave.  Had it been anyone else's question, I would have received the bounty, but since it was my own I did not. Uninstalling Ubuntu from Windows Dual Boot if I don't have Windows recovery CD I installed Ubuntu (I had already had Windows 8.1) from USB (I still have live Ubuntu on it). Is there a way I can uninstall Ubuntu in a way that my Windows will remain bootable? All the tutorials I have seen say that uninstalling ubuntu will delete GRUB also so I will need a Windows recovery CD to boot into it, but I don't have one. Is there a solution? How to remove top and bottom whitespace of longtable? I am using longtable instead of tabular environment and noticed that it puts some additional whitespace at the top and at the bottom of the table. Is there some way to remove it (something less hacky than \vskip -\baselineskip before the table)?  Small piece of code for illustration:  \documentclass[12pt]{book} \usepackage{longtable}  \begin{document}  Linelineline  \begin{longtable}{l l} cell1 &amp; cell2 \end{longtable}  Linelineline  \begin{tabular}{l l} cell1 &amp; cell2 \end{tabular}  Linelineline  \end{document}   And that's what I am getting:    Common tabular environment does not have any additional margins, but longtable does. The batcave, in any version of Batman, is large.  Plus there's the batmobile, which required special construction, plus the batcomputer and numerous other batwidgets.  How did a good sized batcave get built without the land above it being torn up and without requiring a huge construction crew?  And, after the cave was built, how was the batmobile built in secret, without someone involved in it being able to make the connection between the car they built and the one that shows up in the news when Batman is first seen?  (While he's in Gotham, a masked vigilante is news that would end up nation wide.)  There would also be the need for secrecy so vilains can't find out how it is built and what the specs are.  And then there's the continual supply of batwidgets.  Just as with the batmobile, there's the need for these items and how they work to be kept secret.  It'd take several factories to produce all that Batman uses and major construction for any batcave I've seen (which is in movies and on TV).  How is all this done in secret?  (Or is there a trail of bodies?) Making a Comment on a page without being on that page? I have a built a Wordpress site that enables comments on pages and I am using them as reviews, what I would like to do is for someone to be able to make a comment on a page without being on that page.    On the link above, the top right, there is a link that says have your say about a university, it would be good to have a HTML form and then a dropdown box of all the child pages of university-guide; which is where all the universities are stored, and then I can put my comments.php file into this.  So my HTML form appears and when a page is picked from a dropdown box, the comment will then be assigned to that page.  Any help or direction?    New Question for Toscho:  Below is your tweaked plugin to fit into my website, as you can see I have added the select option yearSelect and need this to appear when the comments appear. How would I go about doing this? - Could you provide ay help please?      &lt;?php /* Plugin Name: haveyoursay */  /**  * Call the form in your template with:  * do_action( 'wpse_67527_comment_form' );  */ add_action( 'wpse_67527_comment_form', 'wpse_67527_comment_form' );  /**  * Create a review form.  *  * @return void  */ function wpse_67527_comment_form() {     $select_id = 'page_select';     $url = 'http' . ( is_ssl() ? 's' : '' ) . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];     $url = esc_url( $url );     ?&gt; &lt;form action="&lt;?php echo site_url( '/wp-comments-post.php' ); ?&gt;" method="post"&gt; &lt;h3&gt;Leave us your student perspective &lt;img src="/wp-content/themes/blue-and-grey/images/hmepage-tri.png"&gt;&lt;/h3&gt;     &lt;p&gt;         &lt;label for="author"&gt;&lt;?php _e( 'Name' ); ?&gt;&lt;/label&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;         &lt;input id="author" name="author" type="text" size="40" /&gt;     &lt;/p&gt;     &lt;p&gt;         &lt;label for="email"&gt;&lt;?php _e( 'Email' ); ?&gt;&lt;/label&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;         &lt;input id="email" name="email" type="text" size="40" /&gt;     &lt;/p&gt;     &lt;p&gt;         &lt;label for="&lt;?php echo $select_id; ?&gt;"&gt;             &lt;div class="clear"&gt;&lt;/div&gt;             Pick a university from the list: &amp;nbsp;&amp;nbsp;         &lt;/label&gt;         &lt;?php         // Ordered by page name automatically         wp_dropdown_pages(             array (                 'name' =&gt; 'comment_post_ID',                 'id'   =&gt; $select_id,                 'child_of' =&gt; 2,             )         );         ?&gt;       &lt;/p&gt;     &lt;div class="clear"&gt;&lt;/div&gt;     &lt;p style="margin:10px 0px 0px 0px;"&gt;Please select your year of study: &amp;nbsp;&amp;nbsp;     &lt;select name="yearSelect"&gt;     &lt;option value="1st"&gt;First Year&lt;/option&gt;     &lt;option value="2nd"&gt;Second Year&lt;/option&gt;     &lt;option value="2nd"&gt;Third Year&lt;/option&gt;     &lt;/select&gt;     &lt;/p&gt;     &lt;br /&gt;     &lt;p&gt;         &lt;textarea name="comment" cols="45" rows="8"&gt;&lt;/textarea&gt;     &lt;/p&gt;     &lt;p&gt;         &lt;?php         wp_nonce_field( 'unfiltered-html-comment_' . get_the_ID(), '_wp_unfiltered_html_comment_disabled', FALSE );         ?&gt;         &lt;input type="hidden" name="redirect_to" value="&lt;?php echo $url; ?&gt;" /&gt;         &lt;input type="submit" style="margin:15px 0px 0px 0px; padding:4px 10px;" /&gt;     &lt;/p&gt; &lt;/form&gt;     &lt;?php }  add_filter( 'comment_post_redirect', 'wpse_67527_redirect' );  /**  * Strip '#comment-number' from redirect url.  *  * @param  string $url  * @return string  */ function wpse_67527_redirect( $url ) {     $parts = explode( '#', $url );     return $parts[0]; } ?&gt; I installed some version of Ubuntu on my VMware, but I don't know what version exactly it is. How can I find it out? I don't follow understand what this theorem is saying: "Every function $f: A \to{\cal P}(A)$ is not surjective."   Is this saying so for example let A = {1,2,3} then the power set of A is {},{1},{2},{3},{1,2},{1,3},{2,3},{1,2,3} Is this saying that there is no surjective function that takes every element in each of its power sets to atleast 1 element in A?  Is my understanding correct? It's possible to do a array of Matrix in Matlab? Comments can now be upvoted and flagged. How do those features work? Do users get rep for their upvoted comments? Do upvoted comments have any effect on comment sorting? And can users see their own comment upvote number somewhere?  Related:  The  about comments Highlighting or coloring certain words / substrings appearing in a larger string An interesting exercise about converging positive series, involving $\sum_{n\geq 1}a_n^{\frac{n-1}{n}}$ How to make a complete factory reset, without anyone being able to retrieve my data? When to use a GAM vs GLM I realize this may be a potentially broad question, but I was wondering whether there are assumptions that indicate the use of a GAM (Generalized additive model) over a GLM (Generalized linear model)? Someone recently told me that GAMs should only be used when I assume the data structure to be &quot;additive&quot;, i.e. I expect additions of x to predict y. Another person pointed out that a GAM does a different type of regression analysis than a GLM, and that a GLM is preferred when linearity can be assumed. In the past I have been using a GAM for ecological data, e.g.:  continuous time-series when the data did not have a linear shape I had multiple x to predict my y that I thought to have some nonlinear interaction that I could visualize using &quot;surface plots&quot; together with a statistical test  I obviously don't have a great understanding of what a GAM does different than a GLM. I believe it's a valid statistical test, (and I see an increase in the use GAMs, at least in ecological journals), but I need to know better when its use is indicated over other regression analyses. Currently, the only way to link to a revision (clicking "link"), you just get  which shows what the post looked like at that revision:        Personally, I rarely use this and haven't ever found myself in a scenario (as far as I remember) where I would prefer the way it currently works to what I'm suggesting here.  Could we:   Add another link, or Change the current link   Such that it:   Displays the diff on a separate page (I'd prefer this, since the highlight and scroll thing doesn't always work properly - although perhaps it has something to do with loading images, so it might not apply here, or, if it doesn't, we could fix that instead), or          Highlights and scrolls to a diff, like what is done when you link to an answer () I'm new to Ubuntu. I tried installing it with Windows 8.1, but failed I lost all my files.  I have successfully formatted my PC and installed Ubuntu, but how do I install codecs to play audio and videos files ? Is there an intuitive reason the brachistochrone and the tautochrone are the same curve? The  asks what shape a hill should be so a ball slides down in the least time.  The  asks what shape yields an oscillation frequency that is independent of amplitude.  The answer to both problems is a cycloid.  Is there an intuitive reason why these problems have the same answer?  Proposed operational definition of "intuitive":  Imagine modifying the problem slightly, either to the  (tunnel through Earth), or by taking account of the finite radius of the ball.  If the answer to the original question is intuitive, we should easily be able  to tell whether these modified situations continue to have the same brachistochrone and tautochrone curves. SELECT GETDATE()   Returns: 2008-09-22 15:24:13.790  I want that date part without the time part: 2008-09-22 00:00:00.000  How can I get that? Why does observation collapse the wave function? In one of the first lectures on QM we are always taught about Young's experiment and how particles behave either as waves or as particles depending on whether or not they are being observed. I want to know what about observation causes this change?