What does "What's up?" mean?
What is the meaning, usage and formality of the greeting "What's up"?
How to create an Atlas based on point attributes? Essentially I am wanting to produce an atlas based on a categorical field in a point layer.   i.e. I have a point layer of childcare providers with the categorical field "Provision". I've categorized each feature in this field with "After School Club" , "Breakfast Club" etc, and I now want to produce a set of maps that iterate through each category and show only the points for each. One map of after school clubs, one map of breakfast clubs etc. The extents might be subtly different.  I could do it one by one but it seems like there should be a way to produce an atlas based on the extents of each category? (I do feel i'm missing something obvious :) )   Or alternatively is there a way of automating the creation of a polygon layer and using that as a hidden coverage for the atlas?  EDIT: I've made a little progress with this  - you can use rule based styling to switch on and off features relevant to the current atlas coverage feature.  it actually works fine if all you want to do is show a different set of points. I'm now looking at tying that back to a color scheme and reactive legend. Why does C++ have header files and .cpp files? "wait more than" vs. "wait FOR more than" Not a problem, but have been seeing questions recently of people not being offered upgrade from 18.04 to 20.04.  I thought these upgrades were offered back in June.  I upgraded to 20.04 from 19.10 and this was offered back in May.  Imagine that different versions paths have different schedules, but google does not help explaining(that I found).  Does someone know the schedules? I would like to count subgroups of each order (2, 3, 4, 6, 8, 12) of $S_4$, and, hopefully, convince others that I counted them correctly.  In order to do this by hand in the term exam, I need a clever way to do this because there can be as many subgroups of a group of order 24 as $2^{23}$.  Do you know how to do this?   (I would be most grateful if you could tell me what part of the answer to the old question answers my question before voting to close.) Infinite sum of ideals I've been trying to prove that given a ring $R$ and a collection of ideals $\{I_{\beta}\}_{\beta \in B}$ in $R$, the set $$\sum_{\beta \in B} I_{\beta}=\{f_1+\cdots+f_r:f_j \in I_{\beta_j}, \mbox{ for some } I_{\beta_j}\}$$ is an ideal and is the smallest ideal containing $\cup_{\beta \in B} I_{\beta}$.  I've already proved when I only have two ideals, and so, using induction, I've seen it for finite sums. But I don't see how to generalise that to an arbitrary family of indexes (maybe infinite) $\beta$.   Could someone please give me a hand? Thank you. Does an Animagus's animal form change along with their Patronus? In the two examples shown of an Animagus capable of casting a corporeal Patronus (Minerva McGonagall and James Potter) both had the same animal as their Patronus and as their Animagus animal.  Now, it is also shown that extreme circumstances can change one's Patronus. I think the only example of this was Tonks, which turned from a jackrabbit into a wolf in response for her love of Lupin.  If Tonks (or any other wizard who had their Patronus change) had been an animagus, would her animagus have changed as well? Use of comma separating two adjectives If I had the phrase       two blond haired, blue eyed people    would the comma be out of place?    should I hyphenate "blond haired" and "blue eyed"? Make an exam format with a logo Strange GET requests in logs I'm getting the following GET requests in my apache logs:  109.230.251.14 - - [29/Mar/2011:16:28:18 +0100] "GET http://209.191.92.114/config/pwtoken_get?login=jackmcphee232&amp;src=ygodgw&amp;passwd=e59e2240415e6f1aba3da72b8f189f4e&amp;challenge=9TbU_9yfZhKmzlHtK9X4OkQlesTH&amp;md5=1 HTTP/1.0" 404 1226 "-" "-"   Any idea what it could be and how is that possibly a get request? That IP address seems to point to Yahoo! I'm very confused. I am in the process of creating a LaTeX template for a conference submission, and up until now I've been working only with the anonymous submissions. Now I need to create the "camera-ready" version, which means I need to add authors to the document.   The template is based on article.cls, with some tweaks to meet the font and formatting specifications. The following image contains the examples from the Word template for the conference:    Basically, I need to be able to bold the author's name (which could I suppose be done manually in the document rather than in the template) and more importantly: divide the authors into two columns, with an optional centered last column with an odd number of authors. The font size of the author block corresponds to my \LARGE defined in the class file.  Are there any packages that facilitate this type of conditional formatting, either in a document, or in a .cls file? How can I use those packages to achieve the formatting I require? How soon can I re-apply for a UK visa after getting a refusal? How to hide the .html extension with Apache mod_rewrite How to set the default format in text_format and hide the select? /**  * Implements hook_form_alter().  */ function MODULE_NAME_form_alter(   &amp;$form,   \Drupal\Core\Form\FormStateInterface $form_state,   $form_id ) {    if ($form_id == 'node_article_form') {     $form["body"]["widget"][0]['#allowed_formats'] = ['full_html']; // Your default format     $form["body"]["widget"][0]['#after_build'][] = 'MODULE_NAME_hide_format';   } }  function MODULE_NAME_hide_format(   &amp;$element,   FormStateInterface $form_state ) {   if (isset($element["format"]["format"])) {     $element["format"]["format"]["#access"] = FALSE;   }    return $element; } "There are several reasons proposed for the collapse of the bridge." There are several reasons proposed for the collapse of the bridge.   Is this present simple tense or the present perfect tense? I thought it might be the latter since there is a retrospective aspect to the sentence. However, I am quite unsure. Let $R$ be a commutative ring.  The nilradical $\text{nil}(R)$ is the set of all nilpotent elements, and it is the intersection of all the prime ideals of $R$.  Is the following true in the polynomial ring? $$\text{nil}(R[X])=(\text{nil}(R))[X]$$  Any polynomial in the right hand side has all its coefficients nilpotent in $R$, hence also in $R[X]$, and therefore it is nilpotent in $R[X]$ as the sum of nilpotent elements.  The other inclusion is not clear to me.  Is there a counterexample? What are good advanced books on the physics and science of photography? I am looking for books about the physics of DSLR, including modern photography optics and sensor electronics. If I already have some books on optics and electronics, I have found fairly hard to find good resource for these fields taking photography as a basis, with examples taken from photography and chapters dedicated to lenses optics for instance.  So far what I have found is either too generic, or, if dealing with photography, lacks the physical expertise I would like to get (I mean books with equations. Everybody loves them.)  Good books for physics of photography exist, but they are quite old, the last good I have found were written by Kingslake in the 70s and definitely miss the non-optical part, and the optical stuff is a bit old-fashioned now (but very nice books BTW).  To sum up, I would like:   Very technical references Dealing with physical issues specific to DSLRs and modern photography, such as diffraction limits, image stabilization, properties of coatings, noise correction - whatever you can think of actually...     EDIT: Based on the first results and a quick glimpse at the references given, I would recommend:   The  looks like a bible. Everything seems to be included. It could be a bit more technical, but it gives a lot of bibliography to go deeper if necessary. , for lighting  and  for sensor technology  and the somewhat easier  for optics   Not to forget the , wonderful resource. How do you show that $e^{-1/x^2}$ is differentiable at $0$? Define the real valued function $f(x)$ by $f(x) = e^{-1/x^2}$ if $x \ne 0$ and $0$ if $x = 0$.    How do you show that $e^{-1/x^2}$ is differentiable at $0$? How do you show that this function is infinitely differentiable? When to use a RAM disk? I know that RAM disks are fast, faster than any disk, but they lose their contents on a shutdown of the operating system. The capacity is limited to the RAM. Is there a useful implementation on a new 64-bit Windows 2008 server? How do I install Ubuntu?