Undefined reference when inline specifier used with class member
C++ inlining class methods causes undefined reference
What is the best way to clean lenses and filters? After removing dust with an air pomp and a brush, what are you using to remove stains from the lens and filters?  So far I'm using the liquid from a Giotto's CL 1002 cleaning kit for the lens, but I'm not sure what should I use for the filters, and if there is some better alternative.  Also, what kind of brushes are recommended? If $A$ and $B$ are positive definite, then is $B^{-1} - A^{-1}$ positive semidefinite? Velocity Maxwell-Boltzmann distribution for dummies I have a volume with $N$ molecules; I need to assign to each particle a velocity vector: $$|\mathbf{v}_{i}|=[v_{x}, v_{y}, v_{z}]^{T}$$ for the $i$-th molecule; the velocities must follow the Maxwell-Boltzmann distribution; here is the question: I know the definition of the M.B. distribution, how do I extract the velocities that I have to assign to each molecule? Basically what I want to know is how to calculate $$v_{x}=?$$ $$v_{y}=?$$ $$v_{z}=?$$ for each molecule. Logic Behind StackOverflow Question IDs I'm reposting  I asked on the  SE, bacause I have been redirected to Super User.  I have successfully set up two Linksys routers running DD-WRTv24 to do WDS. They have the same SSID, but different static local IP addresses. There is no security: it's just for testing; no Internet connection.   When I open my notebook, I see the SSID shared by the routers in the list of WiFi access points, and I can connect to it. Once connected, I can ping both routers' local IP addresses, so I know that the WDS is working. But I can't find a way to find out which of them I have actually connected to.  I wouldn't like to have different SSIDs, because I plan to have the access points hand-off users to one another, and I want it to be transparent for the users. I configured one AP to distribute DHCP IP addresses in one range, and the other in another range, so I can discover which AP I connected to at first, but I want a way to discover which AP I'm connected to now, so that I can find out whether the hand-off actually occurred. Human & Alien captured, observed by higher beings From a collection of short stories I read at least 30 years ago. :/  This is going to be incredibly vague, so apologies in advance.  A human and alien (blob/octopus-like...I think) from warring races are captured by an unidentified higher intelligence and put in an enclosure (more like a zoo habitat rather than a prison cell). They are separated by an invisible barrier and can see each other.  I think they were both trying to escape or trying to figure out how they could kill the other first. There was a bulldozer/loader type vehicle they could use at one point to build a shelter (or something).  I believe they were crafting makeshift weapons as well. There was no communication between the two as far as I remember.  The main tension in the story seemed to be was the race to get to the other first.  This has been stuck in my head forever. I know its a very common theme.  The short stories may have included Asimov. What happens when Wild Shape/Polymorph runs out in a space that's too small? How to Pass an Object Method as a Parameter in Delphi, and then Call It? I fear this is probably a bit of a dummy question, but it has me pretty stumped.  I'm looking for the simplest way possible to pass a method of an object into a procedure, so that the procedure can call the object's method (e.g. after a timeout, or maybe in a different thread).  So basically I want to:   Capture a reference to an object's method. Pass that reference to a procedure. Using that reference, call the object's method from the procedure.   I figure I could achieve the same effect using interfaces, but I thought there was another way, since this "procedure of object" type declaration exists.  The following doesn't work, but might it help explain where I'm confused...?  interface    TCallbackMethod = procedure of object;    TCallbackObject = class     procedure CallbackMethodImpl;     procedure SetupCallback;   end;  implementation  procedure CallbackTheCallback(const callbackMethod: TCallbackMethod); begin   callbackMethod(); end;  procedure TCallbackObject.CallbackMethodImpl; begin   // Do whatever. end;  procedure TCallbackObject.SetupCallback; begin   // following line doesn't compile - it fails with "E2036 Variable required"   CallbackTheCallback(@self.CallbackMethodImpl); end;   (Once the question is answered I'll remove the above code unless it aids the explanation somehow.) I'm trying to understand Python's approach to variable scope. In this example, why is f() able to alter the value of x, as perceived within main(), but not the value of n?  def f(n, x):     n = 2     x.append(4)     print('In f():', n, x)  def main():     n = 1     x = [0,1,2,3]     print('Before:', n, x)     f(n, x)     print('After: ', n, x)  main()   Output:  Before: 1 [0, 1, 2, 3] In f(): 2 [0, 1, 2, 3, 4] After:  1 [0, 1, 2, 3, 4] Global hotkey in console application Equipartition of energy Let $u$ solve the initial-value problem or the wave equation in one dimension: $$\begin{cases}u_{tt}-u_{xx}=0 &amp; \text{in } \mathbb{R} \times (0,\infty) \\ u = g, u_t = h &amp; \text{on } \mathbb{R} \times \{t=0\}. \end{cases}$$ Suppose $g,h$ have compact support. The kinetic energy is $k(t) := \frac 12 \int_{-\infty}^\infty u_t^2(x,t) \, dx$ and the potential energy is $p(t) := \frac 12 \int_{-\infty}^\infty u_x^2(x,t) \, dx$. Prove (a) $k(t)+p(t)$ is constant in $t$, (b) $k(t)=p(t)$ for all large enough times $t$.  This is Chapter 2, Exercise 24 of PDE Evans, 2nd edition. I am only doing part (a) right now; my work is shown below: Define $$e(t):=k(t)+p(t)=\int_{-\infty}^\infty u_t^2+u_x^2 \, dx.$$ Then $$e'(t)=\frac 12 \int_{-\infty}^\infty 2u_tu_{tt}+2u_{x}u_{xt} \, dx= \int_{-\infty}^\infty u_tu_{tt}+u_{x}u_{xt} \, dx.$$ Now, I want to get $e'(t)=0$ so that $e(t)$ is constant. How can I go about doing this? I do know that I can use $u_{tt}-u_{xx}=0$, if $t &gt; 0$. With $t&gt;0$ into mind, do I have to consider the $t=0$ case separately? Or can I treat both cases together as $t \ge 0$, since $g$ and $h$ have compact support? During this travel ban (COVID) can my wife come visit me in the USA? I know I can visit there but not sure about her coming here Using ArcPy to Switch Layout Templates? Using ArcMap 10.1, since there is not a way to control portrait or landscape of the layout view through python, is there a way to switch layout templates without opening a new mxd through python?   Since there is a change layout template button it would be nice to have a python function to do the same. Understanding psql prompts I am trying to remove the Facebook and Messenger apps from my Asus Zenphone Laser 2.  Unfortunately, in both cases, I seem to be unable to find the option to fully delete them from the device. I have disabled them, but the app management screen now shows the following:     How can I fully delete/uninstall them? How to edit / how to format box overlapping with footer when scrolling down I just edited an answer on Unix&amp;Linux and when scrolling down, the semi-transparent right sidebar boxes "How to edit" and "How to format" kept their fixed positioning and overlapped with the page footer.     While posting this, I have seen several (not) duplicate questions about this issue, and although from my personal taste, I would prefer the boxes to stop scrolling before the footer is reached, I can accept the development teams decision to let it overlap.   However, on all those other posts, the boxes had an opaque background, so that the footer was hidden and the box content was readable. Here the boxes are transparent though, so the texts get mixed and are no longer well readable. I am trying to testfor a player holding a diamond sword named Notch's Legendary Sword. How can I do that? Who ever gets the best answer will be able to get the first look at my NEW adventure map! Is it possible to disable CPU throttling on a MacBook Pro with a completely dead (not recognized) battery? I have a MBP late 2011 running El Capitan, recently my battery died (x over the icon and "no battery available" in the dropdown.) I've noticed since then that CPU intensive tasks are very slow, and I read that without a battery macs will throttle the CPU to half capacity.  So now I'm looking for one of two solutions:  1) Either somehow disable the throttling, or  2) Trick the computer into thinking it has a battery.  In regard to the first one I've tried a few things such as described , removing a plist file that supposedly controlled it, but that hasn't helped. Any help would be greatly appreciated, TIA.  Edit: I've looked over the question about a 2006 MacBook, it's similar but I've tried everything outlined there and nothing has worked. I'm curious if there are any new ideas. I think the difference may be El Capitan. Specifically, if diary Tom Riddle had succeeded, how would he have strengthened the present day Voldemort?   In , @Pearsonartphoto gives a quote from J.K. Rowling in his answer regarding what would have happened if Tom Riddle had succeeded in fully manifesting from his diary memory form to a full human form.     Q: In Harry Potter and the Chamber of Secrets, what would have happened if Ginny had died and Tom Riddle had escaped the diary?   J.K. Rowling: I can’t answer that fully until all seven books are finished, but it would have strengthened the present-day Voldemort considerably.    - FAQ - Wayback Machine   As well, I've read all seven Harry Potter books many, many times and I haven't been able to ferret out any overt details regarding exactly how the present day Voldemort would've been strengthened by co-existing with diary Tom Riddle.  Specifically, how would the reincarnation of 16-year-old Tom Riddle have strengthened the 67-year-old present-day Voldemort at the time of Chamber of Secrets?  &#9733; I would love an answer from canon, any of J.K. Rowling's interviews, or Pottermore, or an answer constructed within the spirit of canon. Can I find out the return value before returning while debugging in Visual Studio? Take the following function:  DataTable go() {     return someTableAdapter.getSomeData(); }   When I set a breakpoint in this function, is there a possibility to inspect the returned value? go() is directly coupled to a datagrid in an .aspx page.  The only way to inspect the returned datatable is to use a temporary variable. However, that's a bit inconvenient. Isn't there another way?