As a mathematician, my training is to define my terms before I use them. As a computer programmer, I recognize that there are sometimes good reasons to call a method/function/procedure before its full definition has been given. But all other things being equal, I still prefer to define helper methods before they are used rather than afterwards.  However, in TeX programming, the convention seems to be backwards. A simple example of this is the following, taken from :  \newcommand{\utriangle}{\text{\doutriangle}}  \newcommand{\doutriangle}{%   \linethickness{.1ex}%   \setlength{\unitlength}{.8ex}%   \begin{picture}(1,1)(0,-1)   \polygon(0,1)(1,0)(1,1)   \end{picture}% }   (Note: This is taken out of context; don't try to run it by itself.)  Another example is Donald Knuth's definition of the \loop ... \if ... \repeat construction:  \def\loop#1\repeat{%  \def\body{#1}\iterate} \def\iterate{%  \body \let\next\iterate  \else \let\next\relax\fi \next} \let\repeat=\fi   Although I have not tested this, it looks to my eye as if defining \iterate before \loop would have exactly the same effect. [I honestly have no idea about \let\repeat=\fi, since I know \fi constructions can be rather finicky.]  Is this convention arbitrary, or is there a good reason for it? For instance, are there common situations in which the code will break if the helper macro is defined first?

Again and again I see, that TeXnicians define commands and do several things with them in the reverse order, I would do this as amateur. See this example:  In  to  egreg defines a \parttitle, and even more he applies also a patch:  \apptocmd{\@part}{\parttitle{#2}}{}{} \def\parttitle#1{\gdef\theparttitle{#1}} \def\theparttitle{} % initialization   I would have done it in this way - first initialization, then real definition, and last patching:  \def\theparttitle{} % initialization \def\parttitle#1{\gdef\theparttitle{#1}} \apptocmd{\@part}{\parttitle{#2}}{}{}   A test shows, that this works, as well. So, my question is:  What is the advantage of defining TeX commands backwards? (At least from an amateur’s point of view …)


How is blink installed  Ubuntu Focal? nicholas $  nicholas $ sudo apt update Hit:1 https://download.jitsi.org stable/ InRelease Hit:2 http://archive.ubuntu.com/ubuntu focal InRelease                                         Hit:3 http://archive.canonical.com/ubuntu focal InRelease            Hit:5 http://archive.ubuntu.com/ubuntu focal-updates InRelease Hit:6 http://archive.ubuntu.com/ubuntu focal-security InRelease          Hit:7 http://archive.ubuntu.com/ubuntu focal-backports InRelease         Ign:4 https://ag-projects.com/ubuntu focal InRelease                    Err:8 https://ag-projects.com/ubuntu focal Release   404  Not Found [IP: 81.23.228.137 443] Reading package lists... Done E: The repository 'http://ag-projects.com/ubuntu focal Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. nicholas $   Or, can it not be installed through apt repo's?  It must be manually installed?

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


I just removed the cable connected to my computer and switched off the power supply switch. Then I opened the computer case in the side just to gently blow some air to get the dust out. But after just about less than 5 minutes after blowing some air, I closed the CPU and plugged back the power cable and turned on the switch.  But what I noticed was that my keyboard had "Num Lock" "Caps Lock" and "Scroll Lock" lights all lit up even if I did not press the power button in the computer yet. It disappeared as soon as I turned on my computer. When I got to the desktop I got an error: "Default Radeon WattMan settings has been restored due to unexpected system failure" but nothing seems to be wrong. I am just wondering why it never appears except for the time I unplug the power cable and turn off the power switch just now. Is there damage to the computer if you keep removing the power chord? Does it get a power surge or get shocked?

Is unplugging the power from a PC in standby or in normal mode bad for it?


In terms of this definition, I still struggle very much with how the Borel $\sigma$-Algebra is directly related to a Borel Set. Perhaps an example demonstrating how they are directly related? I always see the term B($\mathbb R$) thrown around, but I still don't see a clear connection between that and the Borel Sets! A Borel Set is an element of the Borel $\sigma$-Algebra, if that's the case then what does the Borel $\sigma$-Algebra look like? B($\mathbb R$)= ?  Definition: The Borel $\sigma$-algebra on $\mathbb R$ is the $\sigma$-algebra B($\mathbb R$) generated by the $\pi$-system $\mathcal J$ of intervals $\ (a, b]$, where $\ a<b$ in $\mathbb R$ (We also allow the possibility that $\ a=-\infty\ or \ b=\infty$) Its elements are called Borel sets. For A $\in$ B($\mathbb R$), the $\sigma$-algebra $$B(A)= \{B \subseteq A: B \in B(\mathbb R)\}$$ of Borel subsets of A is termed the Borel $\sigma$-algebra on A.

Definition: The Borel $\sigma$-algebra on $\mathbb R$ is the $\sigma$-algebra B($\mathbb R$) generated by the $\pi$-system $\mathcal J$ of intervals $\ (a, b]$, where $\ a<b$ in $\mathbb R$ (We also allow the possibility that $\ a=-\infty\ or \ b=\infty$) Its elements are called Borel sets. For A $\in$ B($\mathbb R$), the $\sigma$-algebra $$B(A)= \{B \subseteq A: B \in B(\mathbb R)\}$$ of Borel subsets of A is termed the Borel $\sigma$-algebra on A.  I struggle with this part especially "generated by the $\pi$-system $\mathcal J$ of intervals (a, b]" In addition could someone please provide an example of a Borel set, preferably some numerical interval :) Also is $\mathbb R$ the type of numbers that the $\sigma$-algebra  is acting on?


I have Ubuntu Mate 14.04, in case it matters. The Software Updater keeps giving me updates for some Chromium extensions, but I don't even have Chromium. The only browser I have currently installed is Firefox.  I checked the Synaptic Package Manager, searching for "chromium" in the quick filter. It says I have the two following packages:  Extra ffmpeg codecs for the Chromium Browser (chromium-codecs-ffmpeg-extra)  Web browser engine for Qt (codecs) (oxideqt-codecs-extra)  Is there another application using these packages? How can I tell? Should I remove them??  Thanks in advance for the help!

For a specific package, can I find out why it is installed?  So, can I see or it's manually installed, or that it is installed as a dependency of another package? Or that it is installed as part of the distro?


I am currently using various live Linux versions.  In most cases I have the choice between a 64 bit and 32 bit versions.  Does 32 bit have any disadvantages other than slightly lower performance?  What about available software, drivers etc?  Which versions are generally best supported?  One of the machines I might use them on is a 32bit, so those distros are a bit more flexible for me.  Also, if footprint is a bit smaller on a 32bit, there is less data to move from a Live USB etc.  Mainly Mint and Ubuntu for now, but availability of packages are quite important. (Especially system tools)

Speed/Security? Why should we choose to use 64 bit instead of 32 bit?


When I fresh boot my computer everything is dandy.  Then after a few hours applications like Visual Studio, Notepad++, Games, iTunes, Windows components (Cmd prompt, Explorer, etc.), etc. stop working with errors about missing files or not being installed correctly.    I found that if I browse out to Cmd.exe and run it directly (instead of from the menu link) then I can run it, and the WinDir environment variable and others are missing (which explains why I can't run Cmd.exe from the shortcut since it uses %WinDir%\System32 for the path) and the system path is set to (NULL).    When I go to Advanced System Settings (again manually exploring to SystemPropertiesAdvanced.exe) all the environment variables are still there.  I checked my memory utilization and I have 1 of 6 Gig free, with my Commit Charge peak well bellow the limit (like 30%).  The clipboard also stops working too.  Not running anything to exotic, although I do have a lot of Chrome tabs open.  Running Backblaze for backup, Microsoft Security Essentials, and various other utilities.  Closing things one at a time hasn't seemed to fix it.  It has been getting progressively worse (happening sooner and sooner).  Would like to know what is causing it without reinstalling.  Running Windows 7 Ultimate 64-Bit

I have no clue, but lately I've been having this problem. After running my workstation suddenly something destroys PATH and lots of stuff stops working. Initially, my path had MANY directories listed (I use Windows 7 as a development box) and after some time, I only had 3-4 directories listed in my path left.  I can't even open the System Properties dialog where I can see environment variables (because it uses shell variables to start it and it doesn't work). In short, I reboot every time.   Any ideas what might cause that problem? I didn't run anything new/unusual lately. Only VmWare (but I've been using it in the past and didn't have that problem back then).  I just checked, even %WINDIR% is not defined. WTF?!


I have installed Ubuntu 16.04 LTS , but recently experienced Ubuntu Mate 16.04 and think the Mate version is more what I need. My question can I download and install it, or can I just upgrade from Ubuntu 16.04 to Mate 16.04 ?

I have seen several youtube videos that are showing MATE (The Gnome 2.x fork) installed in 11.10. How can I install it to test it out in 11.10 and above.  If it helps the only sources I know of are:  , , and


If an iMac has both cat-5 and WiFi connections to the world, will MacOS use them both to optimize the overall speed?  Or pick only the fastest for everything (since the ISP side of the modem is slower than Cat-5 anyway).  If yes, in what older version (if any) was this not true?  This is NOT a duplicate of any question that has two ISPs.  All devices are connected WiFi to an AirPort Extreme.  One of them is also connected by Cat-5.  I am not currently using USB or Thunderbolt or FireWire.  The Cat-5 obviously has a different IP address than the WiFi.  The Airport goes through a Motorola DOCSIS to the world.  Ookla says the wired connection downloads at 79+ MBps and the WiFi at 50+ MBps.  Also, I wasn't thinking so much of link aggregation, but like letting one app use the wire and another WiFi, giving each app more bandwidth than if they had to shared the same interface hardware.

When I'm connected to two networks with separate routers using Wifi and Ethernet, how does my Mac know what connection to use when I visit a website?


In the universe of Star Trek, Vulcans and Romulans were one species as late as the , about two thousand years prior to the TNG era.  Is there a reliable or standard way to tell the difference between a Vulcan and a Romulan in the absence of any other context (such as genealogies, cultural leanings, etc.)? E.g. will a standard life energy scan correctly differentiate the two? Is there a medical exam that will do this? Is a genetic test required? Will a genetic test reliably differentiate the two, or are there frequent "outliers" that don't match the expected racial genotype?  I recall that there was one episode of TNG where a member of Starfleet was caught lying on their induction paperwork (they were actually 1/4 Romulan rather than 1/4 Vulcan as claimed), but this was only after some time had passed and they had been serving for some time, so presumably nobody noticed anything peculiarly "Romulanesque" about the person during the standard Starfleet medical exams.  As to why there might or might not be a way - consider that real-world humans have been evolving for a lot longer than 2000 years. We don't have a reliable test that will, say, out someone as specifically Slavic, say, as opposed to Greek, or Etruscan. We rely on trends for which there are always major exceptions and complications.

I know that Vulcans and Romulan come from the same parent race. But beyond that, how did they branch off? For how long they have been apart? Are they more different than human and chimps? Can they breed?


I take a coin and with the assumption that it is a fair coin. I throw it 10 times and I get a sequence of 10 consecutive heads. I feel something is unusual and strange, may be the coin is not fair. But the outcome I got is as likely as any other sequences of heads and tails. However there is something really strange here, the probability of getting no tails in 10 throws of a fair coin is really small. So indeed there is something strange here. And common sense says the coin is probably not fair. But isn't "containing no tails" just an arbitrary property of my outcome? May be my outcome is not unusual considering lots of other properties? Or may be you can come by an unusual property for any sequence of heads and tails? My question is why seeing no tails in 10 throws is a good reason to doubt fairness of the coin? P.S.: To abide with the laws of stackexchange my formal question is what I stated above. But my real question is something more general and vague: when we see something strange on what grounds we can say what we saw is just a low probability result of the way I think the world works or I should change my view about how the world works? Are there certain things that I should check before changing my view? I would be grateful if you can help me with my real question too.

Assume that we have a fair coin. We flip it 100 times. The outcome is all heads. Why is it surprising? Doesn't all outcomes have the same probability? Any particular outcome, including irregular ones, would have the same very small probability. Why is it that observing an irregular outcome is less surprising to us than a regular one?


I am kind of new to using command blocks (especially NBT tags) but i want a thrown item to follow me and i tried to make an item (stone) have passenger XPOrb but i kept getting unbalanced square brackets and curly brackets and the command block is confusing me. Here's the command :  summon Item ~ ~1 ~ {CustomName:"Bob",CustomNameVisible:1,Item:{id:stone,Count:1},PickupDelay:1000,{Passengers:[{id:"XPOrb"}]}   I believe its just the end bracket but when i activate the command block i get this error :  [13:13:30] Data tag parsing failed: Unbalanced brackets: {CustomName:"Bob",CustomNameVisible:1,Item:{id:stone,Count:1},PickupDelay:1000,{Passengers:[{id:"XPOrb"}]}   I am very confused but i understand the problem it's just that the fix isn't working. The command itself may even be corrupt for all i know.

Often, when making a command block contraption, you need to set an entity's data tag. These tags can sometimes be very long, with many layers of nested curly and square brackets. For example, this is the command to summon a villager with a single custom trade:  /summon Villager ~ ~ ~ {Profession:3,Career:2,Offers:{Recipes:[{buy:{id:minecraft:diamond,Count:6b}},sell:{id:minecraft:diamond_hoe,tag:{ench:[{id:16s,lvl:10s}]}]}}   The single-line command block interface of Minecraft makes it incredibly difficult to find and fix errors, especially when it comes to mismatched brackets. In fact, for illustration purposes, I put an error in the above command.  What techniques can I use to find and fix unbalanced square or curly brackets when writing long and complicated data tags?


A) Is this a problem/did I do something wrong? b) How can I get rid of these lines in the viewport?

I imported a .dae file but there seems to appear line like objects (and circles at the end of it) starting out from the center of the world. Can you tell me what they are and can it be removed?  But when I open the same environment (.dae file) in another application, I get a proper environment.


Using the Notepad++ product with the "Find In Files" function, I would like to find 2 phrases. (I may expand to more than 2 in the future) The file needs to have BOTH to be a match. Example of phrases:   DIAMETER:     0.750 TURN:     COPPER   I used the regex feature and managed to successfully perform an OR by using this line: \b(DIAMETER:     0.750|TURN:     COPPER)\b but I have not been able to figure out how to perform an AND.   See Above  Every file that has "DIAMETER:     0.750" AND "TURN:     COPPER" should be counted as match. Returned finds, and ##HITS in ##Files EXAMPLE OF TEXT FILE:  DWG REV: D CRO REV: -NA- DAT REV: -NA- SHT REV: -NA- DEIL: PD114D233W(1/2) DICN NUMBER: DF0556-1-1WSM-1P112234-1 TURN: COPPER PIPE LENGTH: DIAMETER:    0.750 THICKNESS:    .109 BEND RAD:   2.500 LAST BEND(PRIMARY): -NA- BEND INFORMATION (ROLL, BEND, STRAIGHT): 0.0       90.0      1.38 0.0        0.0      4.33 TEXT: END1DET:

Obviously, you can use the | (pipe?) to represent OR, but is there a way to represent AND as well?  Specifically, I'd like to match paragraphs of text that contain ALL of a certain phrase, but in no particular order.


Does that a continuous function $f$ of $R$ into $R$ has a local maximum at $(p,f(p))$ implies that there exists $\delta$ such that $f(x)$ monotonically increasing in $(p-\delta,p)$ and monotonically decreasing in $(p,p+\delta)$? I was trying to solve Prob. 15, Chap. 4 from Rudin : "Every continuous open mapping of R into R is monotonic", and I thought it would be pretty easy to solve it if the proposition above holds, but couldn't find any previous answers mentioning it.

This is a homework problem for my real analysis class. It is problem 13.1 from Mattuck's Introdution to Analysis. The question reads:       Suppose F(x) is continuous on some open interval I and c is a maximum point inside this interval. Is it true that f(x) must be increasing immediately to the left of c and decreasing immediately to the right of c? Proof or counterexample. (Note: A constant function is considered to be both increasing and decreasing.)      My friend and I have been attempting to find a counterexample. We figured a function that begins oscillating infinitely many times near c but converges to c would work. We're having difficulty constructing such a function out of elementary functions so we think we will have to define it in another way, piece-wise using receding intervals. I have no clue how this would look. Any advice would be greatly appreciated.


I just installed ubuntu-14.04.2 on my HP elitebook 8440p laptop. I set it for dual boot with windows 7. I set up a 100GB partition for Ubuntu. The laptop has 8GB of RAM and intel core i7 processor. I can bring up Ubuntu when I boot from CD. I can still boot Windows 7. When I try booting up Ubuntu from disk I can see the disk light flashing for a while and my screen goes from completely dark to "slightly lit" but I never get to an Ubuntu login screen. What would be the next step to diagnose/fix this problem?

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


Are both of these statements grammatically correct?  Do they have different connotations?  Or are they interchangeable?   Alice grew far slower than Bob Alice grew far more slowly than Bob

AFAIK the correct grammar for "speak slow" is "speak slowly" (slowly being an adverb). Please correct me if I am mistaken.  But in daily life I have not heard anyone saying "Speak slowlier".  I think I heard folks saying "Speak slower" but I also think it is incorrect.  Which is the best or correct form to convey the message?  Could that be the longish "Speak more slowly?"


Because the GFW of china ban google service, It is hard to use stackoverflow. Currently, I am using a chrome extension to replace google js lib. But today, I meet a big problem - Human Verification. I don't know why stackoverflow see me as a bot.But the bot checker is using google recaptcha:  http://www.google.com/recaptcha/api.js?onload=onloadCallback&render=explicit&hl=en&_=1438579013137  Failed to load resource: net::ERR_CONNECTION_TIMED_OUT   which that chrome extension do not contain...so I can not see captcha, can't pass bot checker, can't post a question.... stackoverflow maybe add more External JavaScript in future, load alternative source would cover more user, make site more strong.  Above is why I make this feature request.

Google's CDN is nice, but it's not 100% reliable for all users. It occasionally fails to load for me. Other users , and some .  It's one more possible point of failure. It would be preferable if Stack Exchange didn't depend on it.  If you don't want to stop using it, consider adding a fallback if it fails to load. Something like this:  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script>   if (!window.jQuery) {     document.write('<script src="https://cdn.sstatic.net/stackoverflow/content/js/jquery-1.7.1.min.js"><\/script>');   } </script>


I am writing an application for the Android platform.  My purpose is; I search the word that I wrote on edit text from a text file. To make this; I used to BufferedReader. ( Txt file size too high so that I used to edit custom properties). My code is working perfectly when It found my word in a text file. But When I search meanless something like 'asdsad'. My code gives me the exception. It is about BufferedReader How can I fix it?   custom properties:  idea.max.intellisense.filesize=999999   My codes:  String text = "";         BufferedReader reader;          try {             InputStream is = getAssets().open("word_families_kopya.txt");             reader = new BufferedReader(new InputStreamReader(is));             String line = reader.readLine();              String translating_string = editText_words.getText().toString();   while (!line.contains(translating_string) && line.toString() != null) {       line = reader.readLine();   Log.i(TAG, "onClick: " + line);         cevirilmis_textview.setText(line);  }       } catch (IOException e) {         e.printStackTrace();     }finally {      }            } catch (IOException e) {             e.printStackTrace();         }finally {          }   Exception message:     read: unexpected EOF!

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


When I bold text inline like strongtext it gets parsed as italics instead of either bold or nothing.  I created the above with the following line:   **strong**text     As I understand it, inline Markdown is disabled here, so this text should really be ignored.

Wrote text in an rtl language (from the  you can see it is done with good reason). I then tried to make bold one letter within the word, while making the entire word in italics -> example.  As you can see, it's actually not connected to the orientation of the language.


The rules for copying spells from other spellbooks are rather clear: you need time and money. However, in case you acquire a new spellbook, things are more fogged.  Can a wizard use two spellbooks at the same time? If so, you only need time to understand it and can forego the costs, right? Otherwise, what happens if you lose your spellbook? Or, must you use just ONE spellbook, possibly attuning to it?

Whether the players killed a mage and got his spellbook(s) or they met with a nice wizard who let him or her learn a spell from his spellbook, can a player prepare a spell from a spellbook that isn't his or hers?  I'm asking because the PHB p. 114 says:     [...] Preparing a new list of wizard spells requires time spent studying your spellbook and memorizing the incantations and gestures you must make to cast the spell: at least 1 minute per spell level for each spell on your list.    emphasis mine   Further, the block on the left as a Copying a Spell into the Book ("the" Book as in "your" Book, since it appears in the block titled Your Spellbook), which explains how you can copy a spell from one book to another, assuming the book is from a stranger, it cost more and takes more time. It actually says:     [...] deciphering the unique system of notation used by the system of notation of the wizard who wrote it. [...]   It continues saying that you have to learn the various parts of the spell (verbose, material, gesture.)  This makes it sounds like a wizard would have a really hard time to prepare a spell from another's spellbook. Is that the case?


I'm really not clear with the subtlety between derivative and differential. Let $f:\mathbb R^2\to \mathbb R$, then the derivative is $\nabla f(x,y)=(\partial _x(x,y) f,\partial _y f(x,y))$ where as the differential is $df=\partial f_xdx+\partial _y dy$. What these notation mean ? Also, I always thought that differential and derivative where almost the same, but with thise definitions, I'm completely confuse.

What is the difference between differentiation  and derivatives of a function ?


I'm having trouble distinguishing the differences when initializing objects using constructors.  I've also read that Bjarne recommends the {} syntax but that it's mostly equivalent to the () syntax so I think that I understand that part.  The problem occurs on line 40 with Car b();.  #include <iostream> #include <conio.h>  class Car { public:     Car() // initialize car     {         std::cout << "Default constructor called" << std::endl;         ++carNumber;     }     ~Car() // destroy car     {         --carNumber;     }      static int getCarNumber() { return carNumber; };  private:     static int carNumber; }; int Car::carNumber = 0;  int main() {      // Equivalent     std::cout << "Car a{};" << std::endl;     Car a{};     std::cout << "Car d = Car{};" << std::endl;     Car d = Car{};      // Equivalent     std::cout << "Car e;" << std::endl;     Car e;     std::cout << "Car c = Car();" << std::endl;     Car c = Car();       std::cout << "Car b(); " << std::endl;     Car b(); // this line      std::cout << "CarNumber: " << Car::getCarNumber() << std::endl;     _getch();     return 0; }   This is the output of the program:  Car a{}; Default constructor called Car d = Car{}; Default constructor called Car e; Default constructor called Car c = Car(); Default constructor called Car b(); CarNumber: 4   I'm confused with "Car b()". I think the compiler is interpreting it as a funcition that returns a Car, but if that's the case I don't see where the function may be implemented (it should cause an error?").  I expected "Car b()" to call the default constructor I made but it doesn't.

Is there any good reason that an empty set of round brackets (parentheses) isn't valid for calling the default constructor in C++?  MyObject  object;  // ok - default ctor MyObject  object(blah); // ok  MyObject  object();  // error   I seem to type "()" automatically everytime. Is there a good reason this isn't allowed?


I've got this example which compiles under MSVC2015 but not Clang. I'm programming code that I want to run everywhere. I get an "error : expected expression" message. I've searched SO but I can't seem to find this exact same problem.  template<int T> class SomeClass { public:     template<int S>     int Foo()     {         return S;     } };  template<int X> void Fun() {     SomeClass<X> c;     c.Foo<0>(); }  int main() {     Fun<0>(); }

In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway?    I have the following code:  template <typename T, typename Tail> // Tail will be a UnionNode too. struct UnionNode : public Tail {     // ...     template<typename U> struct inUnion {         // Q: where to add typename/template here?         typedef Tail::inUnion<U> dummy;      };     template< > struct inUnion<T> {     }; }; template <typename T> // For the last node Tn. struct UnionNode<T, void> {     // ...     template<typename U> struct inUnion {         char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U     };     template< > struct inUnion<T> {     }; };   The problem I have is in the typedef Tail::inUnion<U> dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion<U> names a type and not a function?


Studying mathematical concepts of quantum mechanics, I have recently become familiar with the classical model of one-dimensional particle being scattered by a potential barrier.  As a mathematician, I didn't really have an idea of where such model might be applied in practice. But I have observed that the window beside me has some interesting characteristics similar to this model. I can see both through it, and my reflection in it - clearly some light particles pass through the glass, and others are reflected with unchanged velocity. The thicker the glass would be, the less particles would pass - which is also true for increasing potential barrier width. If I substituted glass with shiny metal, no visible light would pass through and more particles would be reflected, which resembles increasing the potential value in the barrier. And finally (as far as the mathematician I am knows) not all electromagnetic waves pass through glass - which also seems related, because the amount of particles passing through barrier depends on the wave velocity/frequency.  Is there actually some correlation between these models? Is the window semi-transparent behavior induced by this particular quantum scattering phenomena? Or maybe there is a more genera (universal) partial reflection model, that works both in the case of potential barrier and a glass window?

Once I asked this question from my teacher and he replied "Because it passes light.". "And why does it pass light?" I asked and he said, "Because it is transparent.".  The same question again, Why glass is transparent? Why does light pass through it, while for opaque objects, it does not?


Ubuntu 14.04 after installation:  serious errors while checking for drive /.

I have just set up my new system by creating three partitions on a whole hard disk (/boot, /home, swap and /). I saw  article and now I am getting those errors and the system provide me with some options: (I to ignore, S to skip mounting or M for manual recovery).   I am forced to choose skip mounting because I don't know what manual recovery is. Despite the error I get I think that the system boots okay because I can use the system but this error is very annoying.


I have <meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> in the header, but it still shows � instead of µ. I tried adding AddCharset UTF-8 .php to .htaccess, but it didn't help.  EDIT: if I just put symbol µ in the file, it displays correctly. I get � when I try to output it from a database.

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I would like to filter out areas in Germany with post code = 14480. I coded the lines posted below but when I run it returns nothing. How can I fix this? Code: [timeout:3600]; area["ISO3166-1"="DE"][admin_level=2]->.germany; foreach .germany -> .reg (   node.germany(if: t["addr:postcode"] == reg.u(t["addr:postcode"]))   ->.targetArea;   node.targetArea(if: node.targetArea["addr:postcode"] == "14480");   out geom;   );   out;

I am trying to query all the nodes which are in Potsdam city and with postcode 14480. I know that it can be coded as follows:     area["ISO3166-1"="DE"][admin_level=2]->.germany; (   node["addr:city"="Potsdam"]["addr:postcode"="14480"](area.germany); )->.r;  but I would like to use an if condotion with evaluators as shown below in the code. However, it seems that there is something wrong in the code below How can I fix it? Code:     [out:json][timeout:180]; area["ISO3166-1"="DE"]["admin_level"="2"]->.germany; (   node(     if: (t["addr:city"] == "Potsdam") && (t["addr:postcode"] =="14480")   ); );    out geom;


Is there a simple way to flatten a list of iterables with a list comprehension, or failing that, what would you all consider to be the best way to flatten a shallow list like this, balancing performance and readability?  I tried to flatten such a list with a nested list comprehension, like this:  [image for image in menuitem for menuitem in list_of_menuitems]   But I get in trouble of the NameError variety there, because the name 'menuitem' is not defined.  After googling and looking around on Stack Overflow, I got the desired results with a reduce statement:  reduce(list.__add__, map(lambda x: list(x), list_of_menuitems))   But this method is fairly unreadable because I need that list(x) call there because x is a Django QuerySet object.  Conclusion:   Thanks to everyone who contributed to this question.  Here is a summary of what I learned.  I'm also making this a community wiki in case others want to add to or correct these observations.  My original reduce statement is redundant and is better written this way:  >>> reduce(list.__add__, (list(mi) for mi in list_of_menuitems))   This is the correct syntax for a nested list comprehension (Brilliant summary !):  >>> [image for mi in list_of_menuitems for image in mi]   But neither of these methods are as efficient as using itertools.chain:  >>> from itertools import chain >>> list(chain(*list_of_menuitems))   And as @cdleary notes, it's probably better style to avoid * operator magic by using chain.from_iterable like so:  >>> chain = itertools.chain.from_iterable([[1,2],[3],[5,89],[],[6]]) >>> print(list(chain)) >>> [1, 2, 3, 5, 89, 6]

Suppose we have an iterator (an infinite one) that returns lists (or finite iterators), for example one returned by infinite = itertools.cycle([[1,2,3]])  What is a good Python idiom to get an iterator (obviously infinite) that will return each of the elements from the first iterator, then each from the second one, etc. In the example above it would return 1,2,3,1,2,3,.... The iterator is infinite, so itertools.chain(*infinite) will not work. Related


I installed Ubuntu in Legacy mode (BIOS mode) with Windows previously installed in UEFI mode. Turns out this wasn't the best way to do it. Anyway, I couldn't get either of my USB WiFi adapters to work in Ubuntu so I simply deleted the partition it was installed on. On my other computers that only had a BIOS I would just boot up a Windows recovery disk and run a few commands to fix the MBR. If I understand it correctly, doing so would erase GRUB and install the Windows bootloader.  In my current situation I'm not sure what to do. I want to nuke grub. I don't need it as I don't have any flavor of Linux installed. I don't think I want to install MBR either. But maybe I do? I want to continue booting Windows in UEFI mode as that is how I originally installed it.   Will booting my Windows repair USB in legacy mode and fixing the MBR mess with my current installation of Windows? Will it get rid of GRUB?     Windows boots fine in UEFI mode. There is no way to boot Ubuntu in UEFI mode only (as opposed to LEGACY + UEFI mode).    Windows also boots fine in LEGACY + UEFI mode when it is set as Boot Option #1.     Ubuntu fails to boot as expected since I deleted the partition it was on.  Any help would be appreciated.

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.  How do I remove Ubuntu and reinstall Windows?    Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.


How to build your own preset(node) like spider generetor or procedural wire generator?

I have created a fairly complicated node tree in Animation Nodes. There are various parameters of different types that I set on various different nodes.   To make this easier for others to use, I'd like to create a single node, with all the inputs named, so that there's just one place to set all the input parameters. This would look similar to how you get a node group in the materials editor or compositor. AFAIK, Animation nodes does not have node groups.  Is there a way to do this?


I've seen this behavior on multiple meta sites, for example:        As soon as you choose to add a new login (To be honest I only tried Google, Facebook and the OpenId box), you get redirected to a 404 page at [meta site url]/users/authenticate. .  In my opinion, since when trying to login (i.e. first time login) on a meta site it redirects to the login page of its main, the "Add more logins" page on meta should also redirect to its main "add more logins" page. I think this would just make it more consistent.

How to reproduce:  Wander aimlessly into some meta site (either, logged on some other site or not logged at all) Try to upvote/downvote/do something that requires you to be logged in (this will trigger the login or create an account) Click any login option ... ....  What happens? You get a . What this silly user thinks should happen? Either, allow me to login or do not show me the box to login in the first place. Impact? All per-site metas.


We know Muggle parents can have a magical child, but could magical parents have a Muggle child?

‘And what on earth’s a Squib?’ said Harry.   To his surprise, Ron stifled a snigger.   ‘Well – it’s not funny really – but as it’s Filch ...’ he said. ‘A Squib is someone who was born into a wizarding family but hasn’t got any magic powers. Kind of the opposite of Muggle-born wizards, but Squibs are quite unusual. If Filch’s trying to learn magic from a Kwikspell course, I reckon he must be a Squib. It would explain a lot. Like why he hates students so much.’ Ron gave a satisfied smile. ‘He’s bitter.’   Chamber of Secrets - pages 110-111 - British Hardcover   If a Squib is 'kind of the opposite of a Muggle-born wizards' wouldn't that make a Squib more Muggle than wizard? Does a Muggle strictly have to be born to Muggle parents to be considered a Muggle, or can the lack of magic render a person, even of wizarding parentage, a Muggle?  Hermione can say in all truthfulness that she is a 'Muggle-born witch.' The nickname (albeit derogatory) for a Muggle-born is 'Mudblood.' Filch can say in all truthfulness that he is a 'wizarding-born non-magic person,' which, according to Hagrid is a Muggle.  'Squib' may be derogatory in the same way as 'Mudblood' is. Neville laments his family thought he was a Squib when he showed no magical tendencies as a child; the Longbottoms were so rattled at the thought of Neville being a Squib that they, among other things, threw him out a second-story window to see if he would bounce. So could 'Squib' actually be a derogatory term meaning the opposite of 'Mudblood'? After all, the Ministry doesn't allow Squibs to register as magical beings, and many Squibs are schooled and trained in Muggle professions. Squibs don't get a Hogwarts letter.    Wizards can be born to Muggles. Can Muggles be born to wizards?  ETA 11.22.14: In regard to this question, I was glancing through Philosopher's Stone, and I came across this, that Neville said:     ‘Well, my gran brought me up and she’s a witch,’ said Neville, ‘but the family thought I was all Muggle for ages. My great-uncle Algie kept trying to catch me off my guard and force some magic out of me – he pushed me off the end of Blackpool pier once, I nearly drowned – but nothing happened until I was eight.’   Philosopher's Stone - page 93 - Bloomsbury - chapter seven, The Sorting Hat   Could what Neville says contribute to the theory and/or conclusion that Squibs are, or are not, Muggles? How do we apply what Neville said?


Is there a way to find out from where a method was included in Ruby / Ruby on Rails?   For example, from searching the  I know that:   link_to comes from ActionView::Helpers::UrlHelper, and   pluralize come from ActionView::Helpers::TextHelper   But is there a way to find out in Ruby itself? i.e. inirb, or the Rails console?

We recently had a problem where, after a series of commits had occurred, a backend process failed to run. Now, we were good little boys and girls and ran rake test after every check-in but, due to some oddities in Rails' library loading, it only occurred when we ran it directly from Mongrel in production mode.  I tracked the bug down and it was due to a new Rails gem overwriting a method in the String class in a way that broke one narrow use in the runtime Rails code.  Anyway, long story short, is there a way, at runtime, to ask Ruby where a method has been defined? Something like whereami( :foo ) that returns /path/to/some/file.rb line #45? In this case, telling me that it was defined in class String would be unhelpful, because it was overloaded by some library.   I cannot guarantee the source lives in my project, so grepping for 'def foo' won't necessarily give me what I need, not to mention if I have many def foo's, sometimes I don't know until runtime which one I may be using.


Let $f\in \mathbb Z[X]$ be a polynomial of positive degree.How to show that there are infinitely many prime numbers $p$ such that the polynomial $f$ has a zero in $\mathbb Z/p \mathbb Z$ ?  I have no idea of how to start even.  Need help

Let $g(x)\in \mathbb{Z}[x]$, a nonconstant polynomial. Show that the set of primes $p$ such that $p\mid g(n)$ for some $n\in \mathbb{Z}$ is infinite.  I don't know how to start. I have tried asuming that the set is finite but i haven't reached any contradiction.


I am developing a LSTM network with Tensorflow. The Tensorflow  shows that there are different activations for the output of the timestep (tanh) and for the data flowing back in to the network at the next time step (sigmoid). It seems to me that we would want the same activation function for both of these, so the fact that they default to different things is surprising to me.  So why would we want to use different activations and recurrent activations?

I have read several introductory texts about LSTM online, but none of them give a rigorously mathematical explanation of what the model actually does. For instance, why does the forget gate forget any more than any of the other gates in the LSTM unit?  Which papers and/or books should I read if I want to get a deeper understanding of LSTM?


If you scroll down on the Ask Question page you get a 'footer overflow' as seen below:

I have noticed that while asking questions and scrolling to the bottom of the page, the right sidebar containing recent questions covers the footer partially. Also, a part of it goes beyond the browser's boundary. It may not be a big problem but it still doesn't look good.    This also happens on the  page


I want to know the meaning of these strings drwxr-xr-x and drwxrwxr- that appear in the terminal.

Can you explain briefly the main concepts and command line tools used to manage file permissions?


I was wondering how to match a line not containing a specific word using Python-style Regex (Just use Regex, not involve Python functions)?  Example:  PART ONE OVERVIEW 1  Chapter 1 Introduction 3   I want to match lines that do not contain the word "PART"？

I know it's possible to match a word and then reverse the matches using other tools (e.g. grep -v). However, is it possible to match lines that do not contain a specific word, e.g. hede, using a regular expression?   Input:  hoho hihi haha hede   Code:  grep "<Regex for 'doesn't contain hede'>" input   Desired output:  hoho hihi haha


my computer specification  Processor => intel core 2 duo E7300 @ 2.66Ghz  RAM => 3GB DDR2 800MHz  Graphics => AMD radeon HD 5570 1GB DDR3  Hard Drive => 500GB  please tell me can i run the Ubuntu 14.04.1 LTS 64 bit in my computer. thanks in advance.

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I want to add text labels for each panel of an inserted picture (e.g. A B C).  Each individual figure currently exists as pdf and jpg, but I want to join them together into a single pdf with each panel labeled.  I have searched high and low to figure out how to make text sit atop the image and have gotten nowhere (other than to import the pdf and make a new document).  The end product should look like the image below (taken from web).  I have done this plenty of times in Word, etc., but I would like to further my transition to LaTeX.

I am writing my master thesis using Memoir. I want all subfigures to have their labels in the top left corner. I have so far done this with tikz, but I would like to find a more elegant solution as my current solution has flaws.  I would like to be able to automatically reference figures in the text, without having to manually specify the subfigure. This means each figure needs to have a label. Yet if I label the subfigure, said label invariably appears underneath the figure, and I am not sure how to move it, change its color and so on.  Anyway, an mwe and images of current and desired solution:  \documentclass{memoir}  \usepackage{tikz,siunitx,mwe} \newsubfloat{figure}  \newcommand{\scalebarimg}[6]{   \begin{tikzpicture}     \draw node[name=micrograph] {\includegraphics[width=#2\textwidth]{#1}}; %I fetch the image     \draw[ultra thick,#6] (micrograph.south west)++(0.03*0#2\textwidth,0.035*0#2\textwidth)--++(#2*#3\textwidth,0)node[above,midway]{#4 \si{\micro\meter}}; %I draw the scalebar     \draw  (micrograph.north west)  node[anchor=north west,yshift=-1,#6]{\textbf{\small{(#5)}}}; %I draw the image label   \end{tikzpicture} }  \begin{document} \begin{figure} \centering \subbottom[\label{fig:one}]{     \scalebarimg{example-image}{.45}{0.33933}{50}{a}{black} }\subbottom[\label{fig:two}]{     \scalebarimg{example-image}{.45}{0.33933}{50}{b}{white} } \caption{Figures (a) and (b) should not be doubly labeled.} \end{figure}    See Figure~\ref{fig:one} and \subcaptionref{fig:two}.  \end{document}   which yields  but I want   Is there a way of letting LaTeX position the label where I want it to relative the top left corner of the image? Or at least hide the caption for each individual subfigure while still labelling it?


I was born in 2007, when I was a kid and created my roblox account I just typed in a random birthday (I typed in 2015.) Ever since then, I had to deal with hashtags and all kinds of other stuff. I dont wanna create another account because if I did. I would lose all my progress in my groups, My games and all my robux, aswell as friends. So I emailed roblox and chose the ''Change age'' choice. When they emailed me back they said they cant due to COPPA laws. So Im confused on why they would even add that choice if they wont even let you change your age. I know this is long but i really need a answer.

How do you set your age settings on ROBLOX if you accidentally set to under 13? I accidentally put 2008 instead of 1998 in the sign up section. Is there any way to change this, as in settings, age settings are greyed out.


What should i fill in the Surname field while applying for Schengen Visa, if no surname on my passport?  Shall i leave it blank or put my First Name in the Surname field too?

I have a binomial name - Sammy Kumar, name of my father is monomial - Rajiv (no surname)  Will there be any problem in applying for visa to western countries(EU & USA) ?


What drush command can I use to tell drush to use php 5.6 instead of 7.1 which my  site is currently running on.  A million thanks in anticipation.

I'm running Drush on a host that has multiple versions of PHP installed. By default, php --version would give you 5.2.x, but php53 and php54 are also available. So in my .bash_profile I have alias php='php53' (php --version = 5.3.13), which makes Drush work for some commands.  However, I still get "Your command line PHP installation is too old. Drush requires at least PHP 5.3.2" messages for some very useful commands.  A couple of really annoying instances:   drush pm-update will report that it has backed up and then updated all modules and core successfully, then return the PHP version error and restore all backups. In verbose mode, the command that comes before the error is: php /home/[username]/drush/drush.php  --backend=2 --verbose --root=/home/[username]/webapps/drup --uri=http://[domain name]  pm-updatecode-postupdate 2>&1 drush archive-dump will immediately return the PHP version error   The other commands I have tried so far work fine. I'm not sure why this would be, if Drush is sometimes using the php53 binary, and other times not, or if it just has trouble detecting the version correctly, but some very important features are broken for me.


The question asked to prove if $f$ is a polynomial function of degree $n$, and $f\geq0$, then $f+f'+f''+...+f^{(n)}\geq0$  The answer given is: The minimum of $f+f'+f''+...+f^{(n)}$ occurs at point where $0=f'+f''+...+f^{(n)}$[the next term vanishing, since $f$ has degree $n$]. Since $f\geq0$,this means that the minimum occurs at a point where $f+f'+f''+...+f^{(n)}\geq0$  The question is so short, so is the answer given. Why the minimum occurs at $0=f'+f''+...+f^{(n)}$? Does this point always exist?

Let $p(x)$ be a polynomial of degree $n$ satisfying $p(x)\geq 0$ for all $x$. That is, for all $x$, $p(x) = a_n x^n + a_{n-1} x^{n-1} + \cdots + a_1 x + a_0 \geq 0$, $a_n\neq 0$.  Show that $p(x)+p'(x)+p''(x)+\cdots+p^{(n)}(x)\geq 0$ for all $x$ where $p^{(i)}(x)$ is the $i^\text{th}$  derivative.  My interest: I know that, we can rewrite the LDE as follows  $$ p(x)+p'(x)+p''(x)+\cdots+p^{(n)}(x) = Lp(x) $$  where $L := I + D + D^2  + \cdots + D^{(n)}$. Can we say anything about a linear operator of this kind so that it does not change the sign of the input it takes? I can try to solve the question by writing for all the derivatives and factoring them using $p(x)$, but I think there should be a clever way of showing this by the properties of $L$. Can I figure out a solution by just looking at $L$ and the sign of $p(x)$ as in the question? Where should I look for that?


I am using Ubuntu 14.04 on Nvidia Tegra K1 development kit and when I try to move to CLI by pressing ALT+CTRL+F1 (F2, F3, F4, F5 or F6) it take me to a black screen but when I change the resolution of the screen to 1024x768 it works just fine but it doesn't work on any other resolution.   I also tried connecting the development kit to a PC using a serial cable and on Putty it displays everything just fine on the PC but there is no display on the monitor to which the development kit is connected. I want to run the CLI at 1280x960.  The kit is connected to a VGA monitor through HDMI to a VGA converter.

After booting to the GUI in 12.04, I attempt to move to the virtual terminal (or shell, or tty) via Ctrl-Alt-F1 (F1 through F6), and the screen remains blank. I have tried all 6 tty instances and the results are the same. Ctrl-alt-F7 brings me back to the GUI without a problem. Any thoughts?


In Misner, Thorne and Wheeler's Gravitation exercise 21.3, the authors suggest     For a more ambitious project, show that any stress-energy tensor derived from a field Lagrangian by the prescription of equation (21.33) will automatically satisfy the conservation law $T_{\alpha\beta}^{\hphantom{\alpha\beta};\beta}=0$.   Equation 21.33: $$T_{\alpha\beta}=-2\frac{\delta L_{field}}{\delta g^{\alpha\beta}}+g_{\alpha\beta}L_{field}.\tag{21.33}$$  I was able to show that for a scalar field Lagrangian of the form $L(\phi,g^{\mu\nu}\phi_{,\mu}\phi_{,\nu})$ the Euler-Lagrange equation together with the definition of the stress-energy tensor in equation (21.33) imply that $T_{\alpha\beta}^{\hphantom{\alpha\beta};\beta}=0$.  The key point seemed to be the connection between derivatives with respect to $g^{\alpha\beta}$ and those with respect to the field and its derivatives given by the Euler-Lagrange equation.  In the case of a vector field, however, the possible forms of terms in the Lagrangian seem to be infinite (it seems to always be possible to contract a higher tensor power of $\nabla A$ along combinations of "slots" that do not come from combinations of lower powers, unlike the scalar case).  Is this "ambitious project" well-defined and doable?  If so, what is the right way to approach the vector field (or more general) case?

In General Relativity Einstein's equation implies that stress-energy tensor on its RHS is conserved (has vanishing divergence), due to the Bianchi identity. Considering variational principles leading to Einstein's equation leads to conclusion that this stress tensor is equal to the variational derivative of full action with respect to the metric tensor. However, on several occasions I heard people stating that quite generally one can define stress tensor for a field theory in this way and it is automatically conserved. In flat spacetime and without any coupling to gravity! I wonder if this is true. I don't see a reason why it should be.


I would like to copy many files with the below command.   cp `find /Volumes/DATA/ -name "*.app" -depth 1 2> /dev/null` /Volumes/VMWare/img/   But that doesn't work because if it finds a space then it interprets it as the end of the order.  How to fix this?

This question is inspired by    I see these constructs  for file in `find . -type f -name ...`; do smth with ${file}; done   and  for dir in $(find . -type d -name ...); do smth with ${dir}; done   being used here almost on a daily basis even if some people take the time to comment on those posts explaining why this kind of stuff should be avoided... Seeing the number of such posts (and the fact that sometimes those comments are simply ignored) I thought I might as well ask a question:  Why is looping over find's output bad practice and what's the proper way to run one or more commands for each file name/path returned by find ?


Is it ok to install the recent version of Ubuntu in the core i3 processor. Is there any issue coming after installing that. I am new to Ubuntu.

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I am a math student and I'm willing to read a book about the geometry of the universe and space-time with mathematical description. so please introduce some good textbooks.

What are some good books for learning general relativity?


I have a 3 TB internal harddrive and i figured that it would last me a long time. well its filled up and i have no clue how. i do have a couple duplicated movies but only about 40GB in movies all together. and about 30GB in music and 70GB in pictures. so i can't for the life of me figure out why my harddrive is filling up. any ideas? ive already looked at my stats and all i can find is it saying how much is used and not used. when i look at what is using what it all looks right. ive tried a duplicate file finder but that only worked for music for some reason and there were like 70,000 files i would have to manually delete. i don't know what else to do.

My Ubuntu cloud server has left only 900MB of disk space.   I'll just empty the directory /tmp and wondering if there is any other location to clean up.


The Ask Questions page seems to have some issues with the menu on the right.  I noticed it in Workplace and it also seems to affect Meta-SE.  This is not a duplicate of ""  because it is the opposite of what that question is reporting.  e.g.) The menu is NOT covering the footer properly.  To replicate, I simply scroll to the bottom.  I am on Windows 8 running Chrome Version 46.0.2490.71 m  The ask page on SO seems fine.

I have noticed that while asking questions and scrolling to the bottom of the page, the right sidebar containing recent questions covers the footer partially. Also, a part of it goes beyond the browser's boundary. It may not be a big problem but it still doesn't look good.    This also happens on the  page


if a chicken has been in the freezer from November 18 till now July 2 is it safe to cook it and eat it??I'm old and I don't understand

How do I know if a given food or ingredient I have is still good, or if I should discard it?  How can I best preserve a food or ingredient?     This broad question is intended as a "general reference" question to quickly answer many how long will food keep for? questions. Please feel free to edit this question to expand and clarify as needed.


If there's a char* type "37.2", I'd like to change it to float type 37.2, but it's changed to 37.2000008 when I used the atof function. How do I change it to 37.2?

Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


I have decided not to use a plugin to create a simple contact form on my site and used some php code to do the same job. This was so i could style the form exactly how I wanted to. However when I test the form and submit it, the user is sent to the 404 error page despite the url at the top of the browser indicating the contact page that exists. I'm not sure why that would be the case.?  I followed this tutorial to create the template page on my site   Here is the form on my test site

I have a problem with my page. I'm trying to make a "Contact Us" page. It's working perfectly fine design-wise. But when I try to send the form to the same page as origin. It returns 404 error.  It only happens when I'm sending the form. I've tried both with GET and POST requests. Nothing seems to work.  I've even commented out the PHPMailer part. It's caused entirely by the extra variables.  If it helps anything, they're "name", "email" and "message".


Let $a,b,c$ be three real positive numbers such that $abc\geq 1$. Prove that $$\frac{a}{b} + \frac{b}{c} +\frac{c}{a} ≥ \frac{1}{a} + \frac{1}{b} + \frac{1}{c}.$$   Here's what I have done. The expression is equivalent to  $$a^2c+b^2a+c^2b \geq  ab+bc+ac .$$  Denote $f(a,b,c)=a^2c+b^2a+c^2b-(ab+bc+ac)$. We need to show that $f(a,b,c)\geq 0$.   By AM-GM, $a^2c+b^2a+c^2b \geq 3$ (Given, $abc\geq 1$). By AM-HM, $(a+b+c)(1/a +1/b +1/c)\geq 9$ by AM-GM, min value of $a+b+c=3$ so $1/a + 1/b + 1/c \geq 9/3=3$. Thus, The minimal value of $f(a,b,c)$ is equal to the min value of $a^2c+b^2a+c^2b$ minus the min value of $ab+bc+ca=3-3=0$.  Please let me know if there is fault in argument.

I have tried to do a bunch of different versions of AM-GM on this and the equivalent versions that come from substituting in $abc=1$ and I always flip the inequality by doing it.   Help is greatly appreciated.


Thanks to the recent behaviour of SE, I have come to the conclusion I have no desire to remain part of it in any way shape or form, and have had to spend far more time than seems reasonable to delete (or rather schedule for deletion) my account on each site. Although now complete, so my request is unnecessary for me, in the interest of considering others can there be a way to delete a profile on all sites with a single click?

The current process for self-deletion of a user account has several problematic aspects, both in the process itself and in the end result. Some of these issues are:   The process requires manual intervention of a mod or SE employee, leading to delays and sometimes mistakes. It is more complicated than it has to be, which can lead to the impression that SE is imposing some rather arbitrary-looking restrictions and steps one has to take. This can give the impression that the user isn't really in control of his private data at SE. It is irreversible once the account is deleted, although an account can be partially reconstructed with a lot of manual effort from an SE developer. There is no real protection against mod/SE employee errors, if an account is deleted in error, there is no easy way to undo the damage. Because it is manual, it consumes the time of SE employees that have to deal with it  (unless  is used), removing useful voting information and annoying users that lose reputation that way.   I'm proposing an alternative way of handling self-deletion that would be automated, and also reversible to some extent, while still being pretty much a hard-delete (and not a soft-delete that would be problematic with respect to user privacy). The process would work roughly like this:   The user clicks a "delete profile" button in his profile. There should be a way to indicate if you want to delete all profiles on all SE sites, only on this site and a way to select multiple sites from a list where the profile should be deleted. It is verified that the user has true access to the account in some way (confirmation mail?) and not just someone that found the unlocked computer of the user. A countdown until deletion is started (I'd go with 48h, but that could be different). The timer shouldn't be too long, but long enough to correct mistakes and leave users a bit of time to reconsider. Alternative options would be to enable users to override the countdown if they really want to nuke their account immediately. Another option would be to soft-delete the account immediately, and make the countdown only for hard-deletion of the user data. Upon deletion, the posts of the user and his votes are transferred to a newly created blank account, the original account itself is hard-deleted with all the remaining data it contains. The dummy account that holds the user's data should be flagged in some way as deleted, so that the profile links will be disabled, the profile won't be accessible and it won't appear in any user lists.  The user receives a private code that can be used to claim ownership of the account. Other ways are not possible as all private information is removed about the account. This allows for an automatic way of reclaiming most of the important parts of a deleted account. The ability to restore a deleted account might have to be somewhat restricted to avoid misusing it to get rid of the account history. It is more meant as an additional safeguard so that account reconstruction is more easily possible in rare cases. Such additional safeguards might be necessary as the deletion itself would be automatic and without oversight from SE or moderators.   I personally think that the information which posts and votes were connected to a (now anonymized) account is not sensitive enough that it would have to be removed on account deletion. My idea is that this would be close enough to a hard-delete that it satisfies any privacy concerns, but still allow reassociation of posts with a recovered account. The partial reversibility would alleviate concerns about removing the manual oversight by mods and SE employees over the account deletion process.


How do you filter months in mmm format in calendar month order and not alphabetical?  When I do it April as "APR" will be before January as "JAN" for example that is not correct.  (I know that Data > Sort > Custom will do it but I want filter to succeed).  I have also tried customising the data e.g. by shortening mmm-yy to mmm and it does not work.

I need to use filter to sort calendar months in mmm format.  Data > Sort > Custom will do it but I cannot make filter work. Months are in a column eg SEP, APR, JAN, APR, etc.  Filter just does an alphabetical sort so it puts all the APR first.


The  is considered by many to be the most important unsolved problem in pure mathematics. Several attempts have been made in the last 150 years (). RH is the only problem that has been listed in both Hilbert's 23 Problems and the Millennium Problems by the Clay Institute; and yet it remains unsolved, seemingly resisting all attacks, and quickly becoming a piece of mathematical folklore as an "impossible" problem. For instance, it is reported that Hilbert himself declared:  If I were to awaken after having slept for a thousand years, my first question would be: "Has the Riemann hypothesis been proven?"  Implications and applications of this possible result have already been addressed many times on this website (reporting here some of them):     What I'm asking is: why is a conjecture on the zeroes of a specific complex function so hard to prove (or disprove)? What are the main obstacles and obstructions to this problem's solution?  Edit: although the question has already been addressed before on Math.SE ( and, in some way, ), no answers have admittedly been given, and I personally find that the comments this question received in the last hours (for which I am grateful) addressed the problem much more clearly than the comments in the questions above. I believe there's room for improvement, but I apologize if the question is too broad or violates the guidelines in some other way.

I am a Biology major (please don't shame me!) but I really enjoy mathematics. Recently I have been reading about this conjecture and its importance in understanding the distribution of primes. After being studied for so long, how come all attempts have failed? Why is this such a difficult thing to study and work on? Would finding a closed form of $$\sum_1^\infty \frac {1}{n^s}$$ help the issue? Have any attempts been made at this at all? Thank you very much for your time educating me and your help!!


I have an Activity QuestScreen, which at its creation holds the Fragment FragmentQuest. If i press at the Button, this triggers the next() Method of the Screen activity, leading to replace the FragmentQuest with FragmentAction.  The replacing works so far. The problem is, that after the replace i want to set a TextView in the FragmentAction, to avalue which is generated in the  QuestScreen Activity.  My first attempt was to set the TextView outside the onCreatView of  FragmentAction. This lead to a Nullpointer exception adressing the TextView.  So far I have looked at: , ,  and   The attempt seen below leads to an NullpointerException marked in the code.  In The QuestScreen Class   private void next(){      //The needed value for the TextView is stored in nextTransition     Transition nextTransition;     //Check if an entry is in the list     if(quest.getTransitionsAbleToFire().size() > 0){         nextTransition = quest.getTransitionsAbleToFire().get(0);          fragmentAction = (FragmentAction) fm.findFragmentByTag(TAG_FRAGMENT_ACTION);          // create the fragment and data the first time         if (fragmentAction == null) {             Log.d("QuestScreen onCreate" , "create fAction for first time");             // add the fragment             fragmentAction = (FragmentAction) Fragment.instantiate(this, FragmentAction.class.getName(), null);              fm.beginTransaction().add(fragmentAction, TAG_FRAGMENT_ACTION).commit();             FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();             fragmentTransaction.replace(R.id.flFragmentContainer, fragmentAction);             fragmentTransaction.commit();         }          //Triggers the corresponding activity in fragmentAction, to set the TextView to a value which is stored in nextTransition         fragmentAction.nextAction(nextTransition);         nextTransition.fire();      }     else{         CharSequence text = "Quest END";         int duration = Toast.LENGTH_SHORT;         Toast toast = Toast.makeText(getApplicationContext(), text, duration);         toast.show();     } }   In the FragmentAction Class  public class FragmentAction extends Fragment {  private TextView txtYourQuest;  @Override public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setRetainInstance(true); }  @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {     // CREATE VIEWS HERE      View layout = inflater.inflate(R.layout.content_action_fragment, container, false);     txtYourQuest = (TextView) layout.findViewById(R.id.txtV_Your_Quest);     return layout; }  @Override public void onActivityCreated(Bundle savedInstanceState) {     super.onActivityCreated(savedInstanceState); }  public void nextAction(Transition prmTransition){      // --> Here in the enxt Line comes the NPE :  java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.app.Activity.findViewById(int)' on a null object reference      FrameLayout container = (FrameLayout) getActivity().findViewById(R.id.flFragmentContainer);     LayoutInflater.from(getActivity())             .inflate(R.layout.content_action_fragment, container, false);      txtYourQuest.setText("Your " + prmTransition.getAction().getPosition() + ". is to:\n "     + prmTransition.getAction().getActionName()); }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Let: $$f(x) = \begin{cases} 5-x,  & \text{if $x$ is irrational.} \\[2ex] 1+x, & \text{if $x$ is rational.} \end{cases}$$   Prove that $\lim_\limits{x\to 2}f(x)=3.$ Prove that $\lim_\limits{x\to 0}f(x) $ doesn't exist.   Solution Attempt: I want to use the definition of continuity. by saying that for each each $\epsilon>0$ there is a $\delta>0$ s.t. $|x-2|<\delta$  $\Rightarrow$ $|f(x)-f(2)|<\epsilon$. and somehow I thought about using the qualities of $|f(x)|$ and try to get that an equation that might help me in the proof. but got stuck there. any help?

I know the question is a weird title.     Define $f:\mathbb{R}\to\mathbb{R}$ by   $$\begin{cases}     8x & \text{if $x$ is rational}\\     2x^2+8 & \text{if $x$ is irrational}    \end{cases}$$           Determine at which points of $\mathbb{R}$ the function $f$ has a limit and justify your conclusions.   So we see that it is possible that they may approach the same point at $x=2$. Since this is an accumulation point for both parts of the function we can inquire as to the existence of a limit here. We don't consider other points since there will clearly be no other accumulation points that might give the same limit.  I'm confused on how to show the limit formally exists though I am pretty sure it converges to 16 obviously. So I know I have something of the form $0<|x-2|<\delta$ and $|f(x)-16|<\epsilon$. Where I am stuck is talking about the function itself. I don't think showing this with sequences will work but I'm not sure.  Thanks!


I know that in G.C.D domains all irreducible elements are prime.  Does the converse of this statement hold?  If not, is there a weaker condition than being a G.C.D. domain that is both sufficient and necessary for all irreducibles being prime?

One has the following relations for a domain $R$:  $R$ GCD domain $\Rightarrow$ All irreducible elements are prime  $R$ PID $\Rightarrow$ $(R$ GCD domain $\land$ $R$ statisfies ACCP$)$  $R$ UFD $\Leftrightarrow$ $(R$ GCD domain $\land$ $R$ satisfies ACCP$)$  $R$ satisfies ACCP $\Rightarrow$ $(R$ UFD $\Leftrightarrow$ All irreducible elements are prime$)$  $R$ GCD domain $\Rightarrow$ $(R$ UFD $\Leftrightarrow$ $R$ atomic domain$)$  So what is the difference between a GCD domain and a domain where all irreducible elements are prime? What is the "weakest" predicate $P$ such that  $R$ GCD domain $\Leftrightarrow$ $($All irreducible elements are prime $\land$ $P(R))$ ?


How to turn a local network of Ubuntu computers into effectively one computer controlled by a single 'master´ computer on the same network? I think the question is clear. To clarify, I would like to be able to have computers on my LAN contribute to computing tasks run from my 'main' machine. For example, if I am video editing on the 'main' machine, the OS should send other jobs to the LAN computers to execute, and all this automatically, as if it were one machine.

If I had two computers running ubuntu server (or just one) could I "hook" the two machines together to double processing power?  How would that work?


There is special formatting for user links in comments posted by the author of the question; it has a different background, to distinguish it from comments from other users. However, this background is also applied to ♦ moderators when they delete such comments:    I'd expect my user link to be formatted as in the second comment, without special 'owner' formatting.

As they say, a picture is worth a thousand words:    The moderator here is not the original poster, but on the comments by the aforementioned OP, his name has the OP background. On the other comments, he (correctly) doesn't.


I have deja-dup, and it is currently set by default to backup only my HOME directory. I'm about to upgrade my OS from 16.04 to 18.04 and am advised to 'take a backup'. I'm dubious that just backing up my HOME directory is sufficient; but I also don't think I have room to backup everything under ROOT. So please can someone advise me the minimum I should back up in case the upgrade fails? That is, what directories I should back up.

I've recently destroyed my old laptop... but I've saved the ssd. Inside there was a SSD with Ubuntu 19.04 on it and the disk is encrypted.  I've bought a new laptop, and added my old SSD on top of the one already inside the new laptop.  On the new SSD I have Ubuntu 19.10, and from there I can access the data of my old SSD but I was wondering if there was a way to make the old SSD bootable ? Maybe creating a MBR or something like that ?  In the BIOS/UEFI I can see the old SSD in the SATA disks, but it's not in the bootable options, and I've activated the PXE Legacy.  Thanks in advance


I want to get a visa from the Swedish embassy to visit Sweden. May I visit France using the same visa?

In case, if I get a multiple-entry Schengen visa in one of the embassies in Ukraine, Kyiv - should my first trip be to the country which issued the visa?  Any there any requirements of this sort? Does this condition vary depending on embassy which issued the visa?  What are the possible consequences on not visiting that country first? Does it somehow depend on country where the embassy is (i.e. non-Schengen and not EU members)?


I always use google with double quotes to get the answer for similar questions by looking at results number (assuming that the majority are correct), well, it is not the case here. In these days, we intensively use the statement Wish you happy New Year and Wish you Merry Christmas, Well, I have noticed, even here, that some use (a) before happy and merry and some don't. Which one is correct ? Wish you Merry Christmas / Wish you a Merry Christmas for everybody here.

On the very first Christmas card it was written as "A Merry Christmas and a Happy New Year..."   In Wiktionary that same general phrase is "Merry Christmas and a Happy New Year"   A few quick searches in Google show that many people use it without any articles at all:     Merry Christmas and Happy New Year   Does anyone have a source explaining if one of those phrases is more correct than others and if there's any difference implied by the number of articles used?   Edit just to make it more clear: I'm asking for the case when you design a Christmas card, for example, and you have to write the phrase on the card — not personally to anybody, but rather as an impersonally commercial message to the general audience.


I was looking at the thing a familiar could do in combat and found the Help action. The description of the  action is as follows:  You can lend your aid to another creature in the completion of a task. When you take the Help action, the creature you aid gains advantage on the next ability check it makes to perform the task you are helping with, provided that it makes the check before the start of your next turn. Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you. You feint, distract the target, or in some other way team up to make your ally’s attack more effective. If your ally attacks the target before your next turn, the first attack roll is made with advantage.  As I see it the following could be possible:  I, my familiar, and an enemy are standing in a line so that I am standing between my familiar and the enemy. My familiar can use the Help action on me to give me advantage while standing 5 feet from me and 10 feet from the enemy. The enemy can not hit (without ranged attack or reach) my familiar.  This seems strange to me as there are a lot of people saying that a non-owl familiar is very vulnerable when using the Help action as they would be in range of the enemy, but in the situation that I just described it seems that my familiar seems safe. Am I missing something here or is this totally possible?

A player in our group that knows much more than me explained the Help action during game, but then after the game I read the PHB and not sure if he's using it correctly.  I thought I needed to be within 5 feet of the enemy. He said I need to be within 5 feet of the ally.  The  action says:     You can lend your aid to another creature in the completion of a task. When you take the Help action, the creature you aid gains advantage on the next ability check it makes to perform the task you are helping with, provided that it makes the check before the start of your next turn.      Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you. You feint, distract the target, or in some other way team up to make your ally’s attack more effective. If your ally attacks the target before your next turn, the first attack roll is made with advantage.   Does the ally, the enemy, or both need to be within 5 feet of me when I take the Help action?


As I understand it, the F-number of a lens is equal to the aperture diameter divided by the focal length. So f/1 would mean that the aperture is as wide as the lens is long.  Question: Is it physically possible for the aperture to somehow be wider than that? For example, something like an f/0.5 lens?  I gather that F-number is already the number one cause of expensive lenses, so even if such a lens is physically possible, it's likely to be far to expensive to actually buy. (To say nothing about whether it's even useful in the first place.) I'm just curious about the physics of the matter.

Is there such a thing as a maximum aperture that a lens can be open to?  What about a minimum aperture that it can be closed to?  Do these concepts even make any sense?  Is there a lens with the narrowest aperture in the world?  Is there one with the widest?


i have just heard about Ubuntu..I am totally new to it...But I am impressed by the os features..but I have windows 7 installed in my Toshiba laptop...I have some questions to be answer before installing Ubuntu in my laptop..   Can I use windows 7 along with Ubuntu? Will my original windows os will be deactivated post the installation? What are the benefits or better features seen in Ubuntu as compared to those in Windows   Also I have bada os(Samsung wave 3) in my phone, will I will able to install Ubuntu on it?

I need my pre-installed version of Windows 7 (or any other version of Windows), how could I install Ubuntu without erasing it?


I want to use GUID as my ID System,  And I want to be sure that I will always get unique ID.  Should I add a test for uniqueness?

Is a GUID unique 100% of the time?  Will it stay unique over multiple threads?


Recall that an $F_{\sigma}$ set is, by definition, a countable union of closed sets.  We see that $\mathbb{Q}$ is an $F_{\sigma}$ set: $\mathbb{Q} = \cup_{q \in \mathbb{Q}} \{q\}$.  Is $\mathbb{R} \backslash \mathbb{Q}$ an $F_{\sigma}$ set? Note: $\mathbb{Q}$ and anything in $\mathbb{R} \backslash \mathbb{Q}$ are hollow.  I have no idea how to do this.  I know the goal is to use Baire Caegory Theorem.  I think that since anything in $\mathbb{R} \backslash \mathbb{Q}$ is hollow, we have that $\mathbb{R} \backslash \mathbb{Q}$ is a collection of hollow sets, $\{F_n\}$ in $\mathbb{R}$. I don't know how to show the sets are closed or the collection is countable.  Then by Baire Category Theorem, we know that $\cup_{n=1}^{\infty}$ is hollow, but $\mathbb{Q}$ being hollow means $\mathbb{R} \backslash \mathbb{Q}$ is dense  $\mathbb{Q}$ is hollow, that tells us that $\mathbb{R} \backslash \mathbb{Q}$ is dense (which seems to contradict the note, but maybe I'm just not reading it right).   If this isn't the best way to approach the problem, please let me know the better alternative.  EDIT: I think it might be best to prove it as such: Suppose $\mathbb{R} \backslash \mathbb{Q}$ is a $F_{\sigma}$ set.  Then $\mathbb{R} \backslash \mathbb{Q} \cup \mathbb{Q}$ is a countable collection of closed collow sets so by Baire Categoty Theorem, the union of this collection of sets is hollow, but $\mathbb{R} \backslash \mathbb{Q} \cup \mathbb{Q}$ is just $mathbb{R}$, which we know is dense, so we've reached a contradiction

I am trying to prove that the set of irrational numbers $\mathbb{R} \setminus \mathbb{Q}$ is not an $F_{\sigma}$ set. Here's my attempt:  Assume that indeed $\mathbb{R} \setminus \mathbb{Q}$ is an $F_{\sigma}$ set. Then we may write it as a countable union of closed subsets $C_i$: $$ \mathbb{R} \setminus \mathbb{Q} = \bigcup_{i=1}^{\infty}  \ C_i $$ But $\text{int} ( \mathbb{R} \setminus \mathbb{Q}) = \emptyset$, so in fact each $C_i$ has empty interior as well. But then each $C_i$ is nowhere dense, hence $ \mathbb{R} \setminus \mathbb{Q} = \bigcup_{i=1}^{\infty}  \ C_i$ is thin. But we know $\mathbb{R} \setminus \mathbb{Q}$ is thick, a contradiction.  This seems a bit too simple. I looked this up online, and although I haven't found the solution anywhere, many times there is a hint: Use Baire's Theorem. Have I skipped an important step I should explain further or is Baire's Theorem used implicitly in my proof? Or is my proof wrong? Thanks.  EDIT: Thin and thick might not be the most standard terms so:  Thin = meager = 1st Baire category


I am currently running Ubuntu 12.04 LTS and I want to upgrade it to 15.04. However, the update manager shows only 12.10. I tried changing its settings -> all new versions and disabling third party softwares, but it only shows 12.10. I have no pending updates on my system. How do i rectify this problem, without doing a fresh install?

What are the different ways I can use to upgrade Ubuntu from one release to another?


I am trying to learn how a couple of commands works and I want to make a simple script that will change uppercase letters in file names to lowercase. I created that script:  find * -exec bash -c \      'echo "${1##*/}" | tr "[:upper:]" "[:lower:]";' _ {} \;   It works, but it only writes with echo lowercased file names, instead of changing them. On the other hand this piece of code:   find * -exec bash -c \      'tr "[:upper:]" "[:lower:]";' _ {} \;   acts as if I would only use:   tr "[:upper:]" "[:lower:]"   So, I want to learn and understand how to pass filenames that I can get from find and do anything with them using tr. Went already to manuals and google and found nothing.

I have to rename a complete folder tree recursively so that no uppercase letter appears anywhere (it's C++ source code, but that shouldn't matter).  Bonus points for ignoring CVS and Subversion version control files/folders. The preferred way would be a shell script, since a shell should be available on any Linux box.  There were some valid arguments about details of the file renaming.   I think files with the same lowercase names should be overwritten; it's the user's problem. When checked out on a case-ignoring file system, it would overwrite the first one with the latter, too. I would consider A-Z characters and transform them to a-z, everything else is just calling for problems (at least with source code). The script would be needed to run a build on a Linux system, so I think changes to CVS or Subversion version control files should be omitted. After all, it's just a scratch checkout. Maybe an "export" is more appropriate.


What I'm trying to do is to create a \newcommand (not only theorems) and everytime I call that command it adds the chapter number and number of times that I call that command.  For instance, if I'm writting chapter #3 and I created a newcommand called \theorem, this is the output I'm expecting for the first time I call the command:    3.1 Theorem:  Text  I know how to create the new command, I was googling this but didn't find anything relevant. This is the command I'm using:  \newcommand{\mycommand}[2]{%   \textbf{Theorem: #1}\\    #2 }

I use declaretheoremstyle to define a theorem environment, and print a list of theorems in the end of my document:  \documentclass[12pt]{book} \usepackage[english]{babel} \usepackage[margin=2cm]{geometry}% just for the example \usepackage{xcolor} \usepackage{amsthm} \usepackage{thmtools} \usepackage{mdframed} \usepackage{etoolbox}  \declaretheoremstyle[   spaceabove=6pt, spacebelow=6pt,   headfont=\normalfont\bfseries,   postheadspace=1em,   notefont=\bfseries,   notebraces={(}{)},   bodyfont=\itshape,   shaded={bgcolor=yellow!20} ]{thmstyle}  \declaretheorem[style=thmstyle,name=Theorem]{theorem}  \begin{document}  \begin{theorem}[Somebody] ... \end{theorem}  \begin{theorem} ... \end{theorem}  \renewcommand{\listtheoremname}{List of Theorems} \addcontentsline{toc}{section}{\listtheoremname} \listoftheorems[ignoreall,show=theorem]  \end{document}   The theorems are numbered from the beginning to the end of the book, and from 1:    However, I would like to number the theorems with chapter number (like Figures or Tables), for instance, 1.1 (the first theorem in Chapter 1), 1.2 (the first theorem in Chapter 2)...  Does anyone know how to do it?


Some continuous variables like Precipitation have values that can be summed. But others like Temperature do not. Adding two temperatures together simply does not make sense. Do these variables whose values can be summed have an adjective like summable or additive?  To better appreciate the difference between summable and non-summable variables, simply look at a Combination Chart (aka Bar Line Graph) used to display Precipitation and Temperature on the same chart. Precipitation is shown with solid bars, because it is summable, hence could be stacked. Temperatures are shown with a solid line, because they are not; hence do not need to be stacked (and could not).  The issue is not limited to temperatures by the way. And it's important, because of all the quantities defined for the measure of physical phenomenons, temperature is pretty unique. It is one of the very few quantities for which unit conversion cannot be done with a simple ratio. Instead, it requires a ratio and an offset. But other non-summable continuous variables can be found, especially when dealing with percentages. Some percentages are summable, while others are not. And some have their total sum capped at 100%, while others do not, especially when dealing with percentages used to measure variations of another numerical variable.  In that respect, angles are similar to percentages. In some cases, they can be summed. In others, they cannot. And when summed, their total sum might be capped to a certain level like 90 degrees, 180, or 360, or not have any cap at all. For example, a measure of rotation is not capped. But a measure of slope is capped at 360 degrees.  Therefore, it is important to realize that the summable nature of a continuous variable is not a simple factor of its unit. Instead, it is a factor of its unit in a particular context. And I must suspect that the analysis of summable variables should be different from the analysis of non-summable variables. Furthermore, the way they should be graphed are clearly different, as indicated earlier.  Note: the fact that a variable cannot be summed does not mean that it cannot be averaged. Indeed, an average should not be viewed as a sum followed by a division. Instead, it should be viewed as an atomic aggregation, which could be computed in many other ways. For example, Euclidian geometry can be used to compute an average between two values with a compass and a ruler, without having to compute their sums.

The two types of data differ in that if you decide to decrease the temporal (time) resolution of the first type of data you take the mean of lower the resolutions. With the second you take the sum over the lower resolutions. Here is a concrete example  Gas Used (kWh), Outside Air Temperature (C), Time Resolution (Minutes) 100, 20, 20 140, 22, 20 120, 21, 20   Here the hourly (60 Minute) resolution data is clearly  360, 21, 60   and is found by averaging the temperature and summing up the gas used.  What I really wish to know is what the names for each of these types of data are called. I understand that this question is not the best but it is hard to ask a question about something whose names you do not know. If you have a better way of articulating the question then please go ahead and edit it.


I'm new user and I use linux ubuntu about one week. how can I install microsoft office on ubuntu? I see in web sites that I must install samba first but I can't install it. thanks for your helping.

I want to know how to install Microsoft Office (specifically, Microsoft Office 2010) in Ubuntu?   I am a die hard fan of MS Office and I want to know if there is a way I can use it in Ubuntu.


I have one doubt. I know that if the user has delete his account all his voting will be reversed.   I also assume that question and their answers will also be deleted.   But what if there is a protected question post by the user.Will it also be deleted or is there a way to prevent those questions from being deleted ?

I have meticulously read through similar questions, answers and their comments but I still do not understand how the deletion is done. From what I understand I email the customer service and then they do what exactly?     1) They disable my account so that I can no longer use it?      2) They reassign all of my questions and answers to some other   account? To which one?      3) They delete all my questions and answers so that they go away from   public view?   What is the flexibility (if it exists) of the deletion procedure? Is it possible to erase the traces of my former association with the site. Can I request any of the following be done?     4) All of my questions and answers be deleted from public view?      5) Some of my questions and answers be deleted? If yes what criteria?      6) Can I have all of my contributions be assigned to some other   account which runs as sort of a "collective account" and already has   tons of content so that it doesn't happen like my contributions just   move to some other url but still stay grouped under that location and   therefore that location can be discovered as representing my account?      7) Can I have my contributions dispersed through several "collective   accounts?      8) Can my current public name be removed from any comments to my posts   so that my posts cannot be identified later as once belonging to me?   Please be polite with me. I wouldn't have asked if I have found the answer in the other questions. The other questions are also old and it is not clear what the situation is as per 05/2012.  UPDATE (for those interested):  I asked the Stackoverflow team about the procedure. Apparently none of the points 2-8 I asked above are possible, only 1 will take place. The link to my user page from my contributions is going to be removed and replaced with non-clickable text of an anonymized user name like "user1234". Whether this number is the same as my current user_id is not clear. That's all the information I got.  I'm going now to rename myself to "Anonymous" then request the account deletion. Those interested in the procedure will witness the exact result on this page.  Farewell.


Thanks in advance, I'm trying to create an if statement that will help me solve an issue. I want to be able to assign an ID for a button and if that ID matches the  "if statement id entered" it will run my script else it wont do nothing. i'v tried couple of things, but with no luck, I'm new to jQuery hope someone could give a hint,any other suggestion will be great ,cheers.  this is the script I want to run:  jQuery("#myId").append("");   this is what iv tried:  if($('a' == '#myId') {     jQuery("#myId").append(""); }     thanks to all

How can I check the existence of an element in jQuery?  The current code that I have is this:  if ($(selector).length > 0) {     // Do something }   Is there a more elegant way to approach this? Perhaps a plugin or a function?


Some of the sections and subsections of my work has extended titles, i.e.: \section{bla bla bla ....... bla}, so when pdflatex creates my .pdf, the toc gets all pilled-up, as show in picture.    How can I prevent this?

I'm preparing a document using the book class. In the table of contents, the space between the subsection number and title is too wide. How to reduce it?


Placing a bounty on a question changes its last activity timestamp and bumps it to the front page, the same as posting a new answer or editing the question or one of its answers.  It would be nice to be notified when someone else is assigning a bounty on one of your own questions - it might be just a notification in the brand new notification tab of the  StackExchange™ MultiCollider SuperDropdown™ instead of a full inbox message.

Can there be a notification for those people that participated in the question in the past (either who asked or answered it) once a bounty is started on it?


Given is the following double integral - $$\iint\limits_{D}\frac{1}{(x^2+ y^2)^2}\,dy\,dx$$ $D$ is the region for $x\in[1,2]$ and $y\in[0,\sqrt{2x-x^2}]$ How would the limits of integration be derived if one was to convert the coordinate system from Cartesian to polar? So far, I can only understand that $\theta$ would hold an upper bound of $\frac{\pi}{4}$ with a lower bound of $0$ and could derive by algebra that $r$ would hold an upper bound of $2\cos\theta$. By the same algebra, the lower bound for $r$ turns out as $0$.  Here's my go at finding bounds for $r$ $$y = \sqrt{2x - x^2}$$ $$x^2 + y^2 = 2x$$ $$r^2(\cos^2\theta + \sin^2\theta) = 2r\cos\theta$$ $$r^2 - 2r\cos\theta = 0$$ Thus, $r$ is found to be $0, 2\cos\theta$ From a solution that I found, the lower bound for $r$ was given as $\sec\theta$. Could someone please explain how that came to be? I've been at it for a day now

I'm having a problem converting $\int\limits_1^2  \int\limits_0^ \sqrt{2x-x^2}   \frac{1}{(x^2+y^2)^2}  dy dx $ to polar coordinates.  I drew the graph using my calculator, which looked like half a circle on the x axis.  I know that $\frac{1}{(x^2+y^2)^2}  dydx$ turns to $ \frac{r}{(r^2)^2}drd\theta$, which would be $ \frac{1}{r^3}$  The region of integration in  $\theta $ is I guess $0 \leq  \theta  \leq  \frac{1}{4}  \pi $, but I'm stuck for r. The lower boundary is $x=1=rcos\theta \rightarrow r=1/cos\theta=sec\theta$, but what is the upper boundary?? Is it  $\sqrt{2rcos\theta-r^2cos^2\theta}$? I tried this but I couldn't integrate my equation...  Could someone please help me out?  Also, how can I draw the graph of $y= \sqrt{2x-x^2} $? I could only know how it looked like by using my calculator...


A left-sided zero divisor in a ring is a non-zero element $a$ for which there is a a non-zero $b$ such that $a\cdot b = 0$. In a finite ring is it true that we can find a non-zero $c$ such that $c \cdot a = 0$ and vice-versa?   (What I'm thinking to do is constructing the element $c$ somehow, because the ring is finite, but I'm not sure how.)

Let $R$ be a finite ring with unity. Prove that every nonzero element of $R$ is either a unit or a zero-divisor.


I am looking for a TV series that I watched around 2000 - 2005-ish. It was a sci-fi/ fantasy about a young boy traveling with his companions to some places, like caves or maybe other planets, and he was looking for some big glowing and spiky crystals. They were being chased by a dude in a robotic-like armor and helmet, so his face wasn't seen and the color may have been brown, I think. I remember that the dude eventually turned up good and they were betrayed by one of their own. The boy's group also had a creature companion, but I don't remember much about it, only that it was small. I also remember the end of the series - it ended that the boy like woke up or something and appeared in school with his school-mates being those companions.

I'm looking for a 90s (or early 2000s) scifi (mini)series where a boy and old man chase a black guy in metal suit. I think they were going through different dimensions. I remember part of it, but I don't think I ever saw how it ended. I remember my friend telling me there was a twist at the end. I think they were trying to find something and he was always ahead of them..


I'm making a beamer presentation with lots of text in itemize. How to tell latex to move the text to next slide, if the text does not fit the current one? (of course, without creating a new slide)  Also, the apparent "duplicate" is about tables, and the answer did not help.

I have a long table and all are important for sure. It will be tedious if I do trial and error adjustment for the excessive rows.  Shortly speaking, how to force beamer to automatically create frames for the excessive data (in long table)?