Searchable Spinner has caused my app to crash upon filtering the search loaded from firestore
What is a NullPointerException, and how do I fix it?
Integral $ \int_{-\infty}^{\infty}\frac{x^{2}}{\cosh\left(x\right)}\,{\rm d}x $ I need to compute the improper integral $$ \int_{-\infty}^{\infty}\frac{x^{2}}{\cosh\left(x\right)}\,{\rm d}x $$ using contour integration and possibly principal values.  Trying to approach this as I would normally approach evaluating an improper integral using contour integration doesn't work here, and doesn't really give me any clues as to how I should do it. This normal approach is namely evaluating the contour integral $$ \oint_{C}{\frac{z^2}{\cosh\left(z\right)}\mathrm{d}z} $$ using a semicircle in the upper-half plane centered at the origin, but the semicircular part of this contour integral does not vanish since $\cosh\left(z\right)$ has period $2\pi\mathrm{i}$ and there are infinitely-many poles of the integrand along the imaginary axis given by $-\pi\mathrm{i}/2 + 2n\pi\mathrm{i}$ and $\pi\mathrm{i}/2 + 2n\pi\mathrm{i}$ for $n \in \mathbb{Z}$. The residues of the integrand at these simple poles are $-\frac{1}{4}\mathrm{i}\pi^{2}\left(1 - 4n\right)^{2}$ and $\frac{1}{4}\mathrm{i}\left(4\pi n + \pi\right)^{2}$, so that even when we add up all of the poles, we have the sum $4\pi^{2}\mathrm{i}\sum_{n = 0}^{\infty}\,n$, which clearly diverges.  Any hints would be greatly appreciated. Solving "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection" InvalidOperationException The runabouts in Deep Space Nine sometimes have additional equipment on their backs; this is a screenshot from S02E15 (Paradise), showing the Orinoco in the background with the unknown equipment &amp; the Rio Grande in the foreground with a clean configuration:  What is the equipment &amp; why is it only sometimes present? How do you unit test private methods? I´m not sure how to start with this proof, how can I do it? $$ \limsup ( a_n b_n ) \leqslant \limsup a_n \limsup b_n  $$ I also have to prove, if $ \lim a_n $ exists then: $$ \limsup ( a_n b_n  ) = \limsup a_n \limsup b_n  $$ Help please, it´s not a homework I want to learn. I have downloaded and installed the newest  for my Windows 7 (64-bit OS), but when I want to install 64-bit Linux, the New->Create Virtual Machine only displays 32-bit option, no 64-bit option. Could anyone give any clues about this issue? Thanks very much in advance! How can there be animals on the surface in Zion's world? It is apparently canon that  in Neo's day.  However, in the first movie, The Matrix, Morpheus tells Neo that one of the things known for certain is that humans "burned the sky" in order to deny solar engery to the machines, which in turn led to the humans who survived the War being plugged into the Matrix to provide bioelectric energy to supply the machines.  If there's not enough sunlight for solar power, how can there be enough to grow plants to serve as food for animals?  Low levels I can understand -- house plants, at least, thrive in conditions too dim for solar panels to produce cost-effective power -- but every surface scene we see in the trilogy is as dark as a cloudy night; light coming only from the machines.  That wouldn't begin to support photosynthesis, which means all animal life would starve in, at most, a matter of a few years. Search in favorited questions? Setting Blend Width on Mosaic Dataset using ArcMap .NET - What's the best way to implement a "catch all exceptions handler" I'm wondering what the best way is to have a "if all else fails catch it".  I mean, you're handling as much exceptions as possible in your application, but still there are bound to be bugs, so I need to have something that catches all unhandled exceptions so I can collect information and store them in a database or submit them to a web service.  Does the AppDomain.CurrentDomain.UnhandledException event capture everything? Even if the application is multithreaded?  Side note: Windows Vista exposes native API functions that allow any application to recover itself after a crash... can't think of the name now... but I'd rather not use it, as many of our users are still using Windows XP. How do I tell if matrices are similar? Why does my computer get less battery life with Ubuntu compared to Windows? Last year I purchased a Dell Inspiron 5315 laptop shipping with Windows 7 preinstalled. I installed Ubuntu 10.10 alongside it with dual-booting. On upgrading to Ubuntu 11.10, I was upset to find I now get less than one hour of battery life! Windows 7 gives me 2.5 hours of running time.  Is there any possible explanation why  my battery is running out faster with Ubuntu? Can anybody tell me better power options? Prove convergence of the sequence $(z_1+z_2+\cdots + z_n)/n$ of Cesaro means SimpleXML: Selecting Elements Which Have A Certain Attribute Value P.d.f of the absolute value of a normally distributed variable I came across this question as an exercise, had a brief idea, but didn't know how to proceed.     Let $X \sim N(0, 1)$. What is the p.d.f of $|X|$ ?   I know the final p.d.f looks just like the right half of the original pdf, but extended vertically for a factor of 2.  Could someone please show mathematically what the p.d.f of variable |X| is going to be, and explain briefly? Thank you. How to get status start_date and end_date from status_track table? I have two tables:   things:  +------+----------------+------------+ | id   | current_status | created_at | +------+----------------+------------+ | 7770 | active         | 2016-08-09 | +------+----------------+------------+  thing_status_tract:  +----------+-------------+-----------+---------------------+ | thing_id | status_from | status_to | changed_at          | +----------+-------------+-----------+---------------------+ |     7770 | incomplete  | inactive  | 2016-08-09 16:26:22 | |     7770 | inactive    | active    | 2016-08-10 12:31:04 | +----------+-------------+-----------+---------------------+    I need data in the following form. This table has a status and its corresponding start and end timestamp for a particular thing_id:  +----------+-------------+---------------------+---------------------+ | thing_id | status      | status_start_date   | status_end_date     | +----------+-------------+---------------------+---------------------+ |     7770 | incomplete  | 2016-08-09 00:00:00 | 2016-08-09 16:26:22 | |     7770 | inactive    | 2016-08-09 16:26:22 | 2016-08-10 12:31:04 | |     7770 | active      | 2016-08-10 12:31:04 | now()               | +----------+-------------+---------------------+---------------------+   How to do that with a SQL query? In the Deadpool movie when Wade his mutant cells get activated, his skin changes so he looks like Freddy Krueger (As Weasel referred too). But he obtains healing abilities and his cancer gets cured because of it. He's become an immortal person which can heal any wound super fast.  What I don't understand is, why doesn't his skin heal so he would look like before? I remember that Francis (or Ajax) said that it's a 'side-effect' of mutating, but why wouldn't it heal when he has a healing ability? Changing the size of the mouse pointer in Ubuntu MATE 18.04 does not work I have Ubuntu 18.04 with the gnome-desktop  and parallel the Ubuntu MATE desktop installed. While I can easily change the size of the mouse pointer (DMZ-White) in the Gnome3 desktop , this does not work on the MATE desktop. I use for this the dconf-editor.  Maybe someone knows a solution?  Thanks a lot. Do fixtures trigger model callbacks? What is the Page Object Pattern in Selenium WebDriver?