When I try to convert a decimal.Decimal to a string, sometimes Python will output scientific notation (e.g. "123E-2"). >>> from decimal import Decimal >>> str(Decimal('0.00')) '0.00' >>> str(Decimal('0.0000000')) '0E-7'  How can I ensure the output is always in decimal notation (e.g. "1.23")?

Here's my code:  x = 1.0 y = 100000.0     print x/y   My quotient displays as 1.00000e-05.  Is there any way to suppress scientific notation and make it display as 0.00001? I'm going to use the result as a string.


$$\sum_{k=1}^{\infty}\frac{2k^2}{5^k}$$  I came across this problem and I didn't get how to solve it at all. May someone explain this to me?

I'd like to find out why  \begin{align} \sum_{n=0}^{\infty} \frac{n^2}{2^n} = 6 \end{align}  I tried to rewrite it into a geometric series  \begin{align} \sum_{n=0}^{\infty} \frac{n^2}{2^n} = \sum_{n=0}^{\infty} \Big(\frac{1}{2}\Big)^nn^2 \end{align}  But I don't know what to do with the $n^2$.


$Let\ A ∈ M_n(F)$\ such that $A^n = 0$ but $A^{n−1} \neq 0.$  $If\ B ∈ M_n(F)$ such that $AB = BA$, prove that $B = a_0 + a_1A + a_2A^2 + ··· +a_{n−1}A^{n−1} $  for some $a_0,...,a_{n−1} ∈ F.$  I only know that $AB^n = B^nA$, and $\{v,Av,...,A^{n-1}v\}$ is a basis of $F^n$,  but I'm not sure if they are useful.

I am trying to learn some linear algebra, and currently I am having a difficulty time grasping  some of the concepts. I have this problem I found that I have no idea how to start.   Assume that $\bf A$ is an $n\times n$ complex matrix which has a cyclic vector. Prove that if $\bf B$ is an $n\times n$ complex matrix that commutes with $\bf A$, then ${\bf B}=p({\bf A})$ for some polynomial $p$.   All I know at this point is that ${\bf AB}={\bf BA}$.


Define the sequence $P(n)=\sum_{i=1}^{n}p_i$, where $p_i$ is the $i$-th prime number.  I observed for some small $n$ that sometimes this sum evaluates to a prime number, for example $P(2)=2+3=5$ and $P(4)=2+3+5+7=17$ and $P(6)=2+3+5+7+11+13=41$.  So it is natural to ask:     Is it true that there is a sequence of natural numbers $\{n_i:i \in \mathbb N\}$ such that all numbers in the set $\{P(n_i):i \in \mathbb N\}$ are prime numbers?


I have a code from ex colleague. he declared some sort of macro like this :  #define work_dir "/usr/io/track" #define macro_test(a1,a2,a3,a4)\ {\     .name=a1,\     .family=a2,\     .idnum=a3,\     .badlog=a4,\     }   and later on he called this macro like:  macro_test(test "John","macdonald",14,"no");   I know this might not enough detail, however I am just wondering about declaring this sort of macro. it seems to initialize structure but it is not. much appreciated if you can help me.

I want to initialize a struct element, split in declaration and initialization. This is what I have:  typedef struct MY_TYPE {   bool flag;   short int value;   double stuff; } MY_TYPE;  void function(void) {   MY_TYPE a;   ...   a = { true, 15, 0.123 } }   Is this the way to declare and initialize a local variable of MY_TYPE in accordance with C programming language standards (C89, C90, C99, C11, etc.)? Or is there anything better or at least working?  Update I ended up having a static initialization element where I set every subelement according to my needs.


Suppose I have a em wave train.How do I know how many photon does it contain?And where are the photons?(like in the middle or more toward the end of the wave train)The frequency of light that we get from bulbs or sun can be measured so we can accurately state its energy .In this case where does the uncertainty in time ?Moreover when it hits the detector we know about its position so how it causes the uncertainty in momentum?

At the end of this nice video (), she says that  is a chain reaction of electric and magnetic fields creating each other so the chain of wave moves forward.  I wonder where the  is in this explanation. What is the relation between electromagnetic wave and photon?


I really enjoyed doing problems from Irodov while learning introductory physics. But I am not able to find a book like that for Graduate level physics. Can you suggest me a book which has good (and hard) problems from advanced topics like Quantum Theory, QFT, Relativity, etc?

Need to brush up on my late-undergrad and early-grad physics and was wondering if anyone can recommend books or lecture notes (hard copy, or on-line) that also have solutions.   Two that I have come across are:  Princeton Problems in Physics with Solutions - Nathan Newbury  University of Chicago Graduate Problems in Physics with Solutions - Jeremiah A. Cronin  Spacetime Physics - Taylor & Wheeler (favorite book on special relativity; has a lot of problems with solutions at the back; a lot of the problems really enforce the material and discuss paradoxes)  If possible, please also provide a reason why you like the books as opposed to just listing them.


I've been trying to install terminator for my ubuntu 18.04, but I couldn't install it with apt and after adding ppa:gnome-terminator, in apt update I get this error:  Err:8 http://ppa.launchpad.net/gnome-terminator/ppa/ubuntu bionic Release   404  Not Found [IP: 91.189.95.83 80]    There is no bionic release in .  How can I install Terminator?

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?


What's the best way to insert a - (dash/minus character) after every 8 characters in a Java String, starting from the right?  Examples:  1111 -> 1111 111111111 -> 1-11111111 1111111111111111 -> 11111111-11111111 100001111111111111111 -> 10000-11111111-11111111   My attempt, to show that I have tried doing it myself (a comment below asks: "is this homework?":  import junit.framework.TestCase; public class InsertCharacterAfterEveryNCharacters extends TestCase {   public static String insertSpacerAfterNCharactersFromTheRight(char spacer,       int spacing, String string) {     final int length = string.length();     final int newStringCapacity = length + (int) Math.ceil(length / (double) spacing);     StringBuilder stringBuilder = new StringBuilder(newStringCapacity);     for (int i = length - 1; i >= 0; i--) {       stringBuilder.append(string.charAt(i));       if (i % spacing == 0 && i > 0) {         stringBuilder.append(spacer);       }     }     return stringBuilder.toString();   }   public static void testInsertSpacerAfterNCharactersFromTheRight() {     assertEquals("", insertSpacerAfterNCharactersFromTheRight('-', 8, ""));     assertEquals("1", insertSpacerAfterNCharactersFromTheRight('-', 8, "1"));     assertEquals("11", insertSpacerAfterNCharactersFromTheRight('-', 8, "11"));     assertEquals("11111111",         insertSpacerAfterNCharactersFromTheRight('-', 8, "11111111"));     assertEquals("1-11111111",         insertSpacerAfterNCharactersFromTheRight('-', 8, "111111111"));     assertEquals("11111111-11111111",         insertSpacerAfterNCharactersFromTheRight('-', 8, "1111111111111111"));   } }

I have a java string, which has a variable length.   I need to put the piece "<br>" into the string, say each 10 characters.   For example this is my string:  `this is my string which I need to modify...I love stackoverlow:)`   How can I obtain this string?:  `this is my<br> string wh<br>ich I nee<br>d to modif<br>y...I love<br> stackover<br>flow:)`   Thanks


I have 3 questions about installing ubuntu Please help Me.   How much space I have to give to swap partition? My ram is 8GB.  We check two options when installing Ubuntu (one is mp3 fluendo plugin and the other is about restricted extras). Does Ubuntu need internet connection to install them during installation? Is it recommended to have internet connection during installation? Can i download and install everything that Ubuntu downloads during installation later? How?

When I log into my web server via SSH I see the information:  88 packages can be updated. 80 updates are security updates   I tried apt-get update then apt-get upgrade but each time I log in I still see the message about updates. How do I install them?


I have a current Schengen visa until the 8th of September, however I'm planning to go to Greece until the 11th. It's literally a matter of days, but I still need a new visa.   The Greek Consulate has advised me that I cannot apply for a new one while I still hold a valid one. The Swiss Embassy (who issued my current one) has informed me the same, and said that I can 'repeal' my current one. (Not sure if this is the same as "cancelling" or 'revoking' my visa). The Greek Consulate however, has said that this would look bad for me in future applications (apparently it will not mention WHY my visa was cancelled) and have suggested that I overstay my visa rather and just pay the fine. That, however, is not an option for me, as I travel to Europe often and would rather not stay in a country illegally and risk being blacklisted for future trips.   Does anyone have any advice? I really feel like I am being forced to illegally overstay my welcome or change my flights. All I want to do is apply for a new one in the correct and legal manner.

My wife has a Schengen visa issued by the Italian consulate in the UK.  It expires at the beginning of December, and as we want to travel to Europe for the Christmas holiday, we were hoping to cancel the current Schengen visa early in order to apply for another one in time.  I have contacted the Italian consulate in London by email, and they have told me that they are unable to do this.   After a quick search online, it seems other people have had more luck cancelling their visas.   So my question is: has anyone cancelled a Schengen visa issued by Italy, and if so - how?


For example:  S ::= “Sales will go up.” E ::= “Expenses will go up.”  Express the following: Both sales and expenses will fall.  Why is it  ¬ (S ∧ E)  instead of ¬S ∧ ¬E ?

Let $S$ represent the English statement "Sales will go up."And let $E$ represent the English statement "Expenses will go up." Now my problem is that I have trouble telling the difference between these two statements: $\neg(S\land Q)$ and $\neg S \land \neg E$. When these two statements are translated into English they sound,to me, the same. However, when you look at their truth tables they are different.   Here is my best translation of these two statements:  1) $\neg(S\land E)$ represented in English, "Both sales and expenses will not go up."(Correct me if I translated it wrong)  2)$\neg S \land \neg E$ represented in English, "Expenses will not go up and sales will not go up."(Again, correct me if I'm wrong)  I still do not understand the difference between these two statements in the English representation. They both sound the same thing to me.  Once more, I have the same trouble I have with understanding with the or-connective( $\lor$ ). Again let E and S be the same statements as before.Tell me if I might have translated them wrong.  1) $\neg (S \lor E)$ represented in English is "Neither sales nor expenses will go up."  2)$\neg S \lor \neg E$ represented in English is "Sales will not go up, or Expenses will not go up."  Yet I still have trouble understanding the difference between the English translation.  In short, can you give me some alternative example that better explains the difference, something intuitive that gives me a clear picture of the difference of the meaning between the statements I showed with the connective-or and connective-and. Thank you.


When I open my print project in print composer, my map is not there upon opening. There is only a little note that says "your map will print here".  What is going on here?

I just updated from QGIS 1.7 to 2.0 on Mac. When I now open a project and create a map in the print composer the content of the map is lost when I open the project again later. The settings of the stored print are still ok, but the map content is not displayed. Instead it just says "Karte wird hier gedruckt" which means "map to be printed here" in English.   Does anybody have an idea what the problem could be? It always worked fine with 1.7.


Let's consider 2 functions, void fooA(int argc, ...) and void fooB(int argc, ...)  I need to pass the variable arguments I get from fooA to fooB. And except for passing them to fooB, I never need to handle these variable arguments in fooA.  I tried something like changing fooB to void fooB(int argc, void* argv) and pass the arguments like in the following code:  void fooA(int argc, ...)    {     // Some processing ...     va_list list;     va_start(list, argc);     void **argv = NULL;      argv = malloc(argc * sizeof(void*));     for (int i = 0; i < argc; i++)         argv[i] = va_arg(list, void*);      fooB(argc, argv); }   But it's not very clean, and I would like to know if there is a way to do that without even handling the variable arguments in the fooA function.  EDIT: It's not a dupe of  because in my case I can modify fooA or fooB definition (even if I would not like to). And even if it works great, I can't accept Jonathan Leffler technical because I just can't put a forwarder for each fooB-like function. They are called with a static function pointer array and I need to have all my fooB methods alone in the same C file.

In C, is it possible to forward the invocation of a variadic function? As in,  int my_printf(char *fmt, ...) {     fprintf(stderr, "Calling printf with fmt %s", fmt);     return SOMEHOW_INVOKE_LIBC_PRINTF; }   Forwarding the invocation in the manner above obviously isn't strictly necessary in this case (since you could log invocations in other ways, or use vfprintf), but the codebase I'm working on requires the wrapper to do some actual work, and doesn't have (and can't have added) a helper function akin to vfprintf.  [Update: there seems to be some confusion based on the answers that have been supplied so far. To phrase the question another way: in general, can you wrap some arbitrary variadic function without modifying that function's definition.]


How can I get unicode text to appear under the square-root symbol?   \documentclass{article} \usepackage{fontspec} \newfontfamily\myfont[Script=Devanagari,Scale=1.0]{Sanskrit 2003}  \begin{document} Normal text: $\sqrt{hello}$ \\ Testing unicode text under square root: $\sqrt{1.1{\myfont भू सत्तायाम् }}$ \end{document}   The above fails to print any of the unicode text in sanskrit:

Lets say I have something like:   \[ Let x = number of cats \]   (This is a contrived example, but pretend we are actually inside a long align environment block...) "Let" and "number of cats" need to be written like normal text, while x= needs to be math type text.  I've seen this:  \[ \mbox{Let } x = \mbox{ number of cats} \]   and this:  \[ \textrm{Let } x = \textrm{ number of cats} \]   They seem to produce equivalent output, but I'm not sure which is the "correct" one. Also, they are not ideal in that the extra space needs to be placed inside the text mode block, otherwise it is ignored as math mode and butts the text right up against the math.  Ideally there would be some command which allowed embedding text into an equation, which correctly inserted leading and trailing space around the block as required without adding space inside the text block.  How does one do that "correctly"?


Bob has a High-Deductible Health Plan (HDHP) and wants to maximize his contributions to his Health Savings Account (HSA). At some point during the year, Bob changes his health insurance from an HDHP to a non-HDHP. How much can Bob contribute to his HSA during this year?

What is the HSA contribution cap for a person that is only enrolled in a HDHP for part of the year?  For example, consider a single participant that   was not previously enrolled in any other health plan has not made any HSA contributions that year will be enrolled in the HDHP on Dec 1 (and possibly Dec 1 of the following year)   Would it be a pro-rated amount or the full $3300?


Assume $n = k$:  $$(k+1)! -1 = 1!\cdot 1!\cdot1+...+k!\cdot k$$  To test for $k + 1$, I add $k+1$  to the sum as new element and equate its sum with that of the first $k$ elements with the formula adjusted for $k+1$:  $$(k+1)!-1+(k+1)!(k+1) = ((k+1)+1)! -1$$ $$(k+1)!+(k+1)!(k+1) = (k+1)(k+1)!$$ $$(k+1)! = 0$$  Equation doesn't hold water. What I did do wrong?

How do I go about simplifying this:  $$\sum_{k=1}^nk \cdot k!$$  Wolfram alpha tells me it's the same as $(n+1)!-1$ but I don't see how.


I am going over Durret's probability textbook and one of the proofs uses the inequality  $$\sum_{k=n+1}^\infty \frac{1}{k^2\log k} \leq \frac{1}{n\log n}$$  But, as with much of the textbook, gives no explanation. I was thinking you could take one of the $k$'s out front to and then integrate $1/k\log k$ but that doesn't seem to be of much help.  How can I show this to be true (rather than just take Durret's word for it)?

I would appreciate some help proving the inequality $$\sum_{k=n+1}^{\infty}\frac{1}{k^{2}\log k}\leq\frac{1}{n\log n}.$$ Thanks in advance!


I'm new to SEO (but I know the basics). I've looked up several videos on youtube so far and the common factor among all of them is good content. The videos I've watched or the SEO tips I've read mostly focus on the strategy of creating good content by writing articles, getting others to contribute and link to them, and so on. With superior content, they can capture the attention of domain experts, or brands, or related websites, etc. and get backlinks/social shares from them.  However, aren't there some keywords for which one doesn't necessarily need good content? For example, something like "mechanic jobs" or "delivery boy jobs", and so on. Another example would be something like, "join pdf" or "compress pdf". The top results for such searches don't have any content at all, rather, just webpages that list the jobs or webpages that provide the joining/compression service. For example, please refer to these:  (searched for "delivery boy jobs")      (It's clear that the top results given above are customized according to my location, even though I didn't include any location in my search term)  What do sites as given in the above examples do to be so high in the rankings?   Of course, one obvious reason could be that they've been around for a long time and have the first mover advantage, but I can't understand how sites can "growth hack" their way to good page rankings without having any scope to create quality content, and therefore, without any means to distinguish themselves significantly from their peers. Do none of the SEO "growth hacking" techniques apply to sites like these?

What are the best ways to improve a site's position in the Google search results?


I am not a native speaker, I do not know how to say this properly: "It should be always on", or "It should always be on"? Is there any difference?

For example:     Ever wish you could share information broadly   Could it be rewritten to:     Ever wish you could broadly share information   Are there any rules for the position of the adverbs.


Let $k=\mathbb{C}$ and $ A=\left \{z \in \mathbb{C} \mid \mbox{Im}(z)\geq 0  \right \}$. I see intuitively that this cannot be expressed as the zero locus of a finitely number of polynomials, but how can you justify that it is not a variety with the following abstract definition of an affine variety?

The question is stated as follows,     Q. Let $R=\{(x,y):y>0\}$ be the upper half plane. Prove that $R$ is not an affine variety.   My attempt was simply first assuming that it is an affine variety and seek for a contradiction. However, I could't proceed further and the solution is as follows     A. If $R=V(f_1,...,f_s)$ then each $f_i$ vanishes on $Z^2_{M_i+1}$ (Note:Though the format is not $\mathbb{Z}$ in the solutions for this "Z" but it probably means "integers") where $M_i$ is the largest power of $x$ or $y$ in $f_i$.   My request is, could someone render the above statement in a somewhat more colloquial or a simpler way? What I do not understand is, why "$R=V(f_1,...,f_s)$"  implies "each $f_i$ vanishes on $Z^2_{M_i+1}$." If $M_i$ is the largest power of $x$ or $y$, why $M_i+1$?  Perhaps another slight confusion is, I am familiar with notation $\mathbb{Z}^n_{\geq 0}$ which means, for the subscript, "elements of the $n$-tuples are $\geq 0$" but here, $Z_{M_i+1}$ means...what? Does it mean all elements are $\geq M_i+1$ though it does not have the "$\geq$" sign?     (continued solution) Thus each $f_i$ is the zero polynomial and so $V=R^2$. Since $R^2 \neq R$ we have a contradiction.   I believe this statement has to do with $f_i$ having "more solutions than its degree $M_i$(implies $f_i$ must be the zero polynomial)" but, since I am not clear with the statements above, I am unsure. And finally, I don't see how this leads to the conclusion  "$V=R^2$."  Essentially, I am full of question marks here. I'll try the thinking on my own once I see what the solution is trying to say. Right now, I don't even see what it's trying to convey due to the lack of my knowledge.  So it would be great if someone can elaborate this solution based on my confusion stated above. Thank you, please comment if anything is unclear


I understand the idea behind regressions and know how to interpret them, however, when I hear the term "capturing the effect of.." or "controlling for.." so far I've just accepted it without questioning how the regression actually manages to do so, just by including a variable in the equation.  Can somebody explain (maybe even with math) why exactly this capturing of effects or controlling for variables works just by including a variable in my regression?

Here is the article that motivated this question:   I liked this article, and it nicely demonstrates the concept of “controlling for other variables” (IQ, career, income, age, etc) in order to best isolate the true relationship between just the 2 variables in question.    Can you explain to me how you actually control for variables on a typical data set?      E.g., if you have 2 people with the same impatience level and BMI, but different incomes, how do you treat these data?  Do you categorize them into different subgroups that do have similar income, patience, and BMI?  But, eventually there are dozens of variables to control for (IQ, career, income, age, etc)  How do you then aggregate these (potentially) 100’s of subgroups?  In fact, I have a feeling this approach is barking up the wrong tree, now that I’ve verbalized it.  Thanks for shedding any light on something I've meant to get to the bottom of for a few years now...!


Hi I have an issue with Path.Combine that it does not return the corect result. Here is what I mean.I ave to combine 4 strings into a bath:  string basePath = "D:\\Programare\\Visual Studio\\TFS Workspace\\CodeArt\\Development\\CodeArt\\Backend\\WebApi\\CodeArt.WebApi\\bin\\..\\Content\\" string userId = "4d52ec77-966a-480a-a4c3-c1ff67438fe9"; string filePath = "\\Avatar"; string storageFileName = "ffdc24a9-f553-41ce-aa33-042b07fcfdab.png";  var result  = Path.Combine(basePath , userId , filePath , storageFileName);   Now for some reason my this code returns only "\Avatar\ffdc24a9-f553-41ce-aa33-042b07fcfdab.png".  Am I doing something wrong why am aint Path.Combine concatantes all the string.

From the Immediate Window in Visual Studio:   > Path.Combine(@"C:\x", "y") "C:\\x\\y" > Path.Combine(@"C:\x", @"\y") "\\y"   It seems that they should both be the same.    The old FileSystemObject.BuildPath() didn't work this way...


Yoda, being a Jedi grand master, should have better communication skills given that he is supreme leader among the Jedis. Why can't he learn to speak English properly?

Yoda's unique speech consisting of reversed grammar is iconic.  Is there any reason he has adopted this speech pattern?  All other alien species encountered seem to have no trouble speaking normally. Why does Yoda speak in this way?


Idea behind this is to have a "Search" textfield. When user types in some data and clicks on a button. Another window opens with data according to typed into "Search" textfield. I create my textfield like this TextField search = new TextField();  On a button click I do this:  searchButton.setOnAction(e -> {             String st = search.getText().toString();             System.out.println(search.getText());             setSt(st);             InfoWindow.display("Detailed information on " + st);         });   setSt() method looks like this:  public void setSt(String st)     {         this.st = st;     }   this.st is declared like this: private static String st;  In the informational window class I try to evaluate what user typed in:  public static void display(String title){     Stage window = new Stage();      window.initModality(Modality.APPLICATION_MODAL);     window.setTitle(title);     window.setMinWidth(250);     String st = MainClass.getSt();     if(st == "M16"){         textLabel = new Label("The M16 rifle, officially designated Rifle, Caliber 5.56 mm.\n" +                 " M16, is a United States military adaptation of the Armalite AR-15 rifle.\n" +                 "The original M16 was a select-fire, 5.56×45mm rifle with a 20-round magazine.");     }     VBox layout = new VBox(10);     layout.getChildren().addAll(textLabel);     layout.setAlignment(Pos.CENTER);     Scene scene = new Scene(layout);     window.setScene(scene);     window.showAndWait(); }   getSt() method looks like this:   public static String getSt() {     return st; }   I've went through the program flow with the help of the debugger. It get's to the point of evaluation if(st == "M16") and I can see in debugger that st = "M16"(because I've typed that in "Search" textfield), but it doesn't get into the 'if', it just continues as if condition would be false. What could be the problem here? Can you help to figure it out? It is definitely not in the reach of my knowledge.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Which is correct?  Two-thirds of the food I eat are vegetables. Two-thirds of the food I eat is vegetables.  The first one sounds right to me, but would the second be more "grammatically" correct?

Is 2/3 always, sometimes or never plural?  E.g.     1a) 2/3 of the pizza were eaten.     1b) 2/3 of the pizza was eaten.      2a) 2/3 of the visitors were men.     2b) 2/3 of the visitors was men.   I feel that example 1 could go either way but example 2b sounds very wrong.  Is there a rule for this?


I am using Ubuntu 18.04 (Bionic Beaver). When I launch software updater from the launcher it does not connect to the server to download updates. It always posts "Try again." I always check network settings & I am connected. If I click ok after and try it again, it downloads the updates - so how do I fix this issue? I have tried to delete it just to reinstall it but no luck

I havent used my Ubuntu for quite a long time.  Today, when I booted Ubuntu (14.04 LTS), the software updater and Software & Updates (from Settings) are not working.  The software updater's window will show up for around 1 sec, but it will close automatically. Software & Updates is never shown, no matter how many times I click the icon. Note that neither of them show any error message.  Those 2 features were working perfectly the last time I used Ubuntu. I want to do some system upgrade and update.  For now, I use sudo apt-get update && sudo apt-get upgrade. This command runs very fast, meaning (I think) my Ubuntu is not updated properly. The update from software updater always has a big size hence the download should be slower.  What should I do?   Can I just uninstall and reinstall both of them? If I can, how to do it?  Just to clarify, I don't want to upgrade my Ubuntu version (I want the LTS one), I just want to upgrade the software/packages I used.  Thanks for your time.


I've got an external drive with 3 volumes on it. All of them are mounted upon connecting the external drive to my Mac.  I want one of these 3 volumes to not be mounted when I connect it. Is that somehow possible?

I have an external HDD with 4 partitions.  My question is the following: is there a way of telling the OS to mount just two of them (One FAT and one HFS+) when I connect the HDD? It is rather annoying to have 4 "disks" connected on the finder, and it makes ejecting the drive a test to my patience.   I would appreciate your suggestions. If it's impossible I guess I'll just have to fiddle around and get everything in 2 partitions... :/


I'm looking for the cheapest round-trip ticket from Ho Chi Minh ( Vietnam ) to Los Angeles. The minimum price is around 670 USD. On the contrary, If I book the ticket from Los Angeles to Ho Chi Minh (Vietnam), it only costs 493 USD.   I used Skyscanner / Momodo / Google flight, etc. to try to get the better deal, but those do not work.   Do you know why the flight from US cities to Vietnam is cheaper than from Vietnam to a US city?

I had planned for my wife, daughters and I to take a holiday from our home in China to the UK for a few weeks in July. Usually, when people visit us in China from the UK, the cost is around £450 to £500 for a return flight. Looking online, I can see that such tickets are available. However, when I looked at the flights from China to the UK the costs for return tickets were in the £850 to £1,000 range.  This seems unfair. Buying the same ticket on the same airplane results in vastly different prices depending on your origin. What justification is there for airlines to charge double the price for return flights from China to the UK and back as for the return flights from UK to China and back?  As it stands this will end our vacation plans as the cost has gone from an expensive £2000 trip for the family to an astronomical £4000 trip, equal to my entire years salary.


I am looking for a way to prevent Windows from freezing. I know that because of the halting problem, there is no way to totally prevent any program from being in an infinite loop, but my problem is more tractable I think: I just want to detect freezes and do an action accordingly (kill process or reboot).  Sometimes, my work computer gets frozen for various reasons, which can range from a faulty program consuming too much RAM to an external USB hard drive that stops responding and makes the whole OS freeze.  However, I need my computer to always be up, because if it freezes it stops background computations that I left, and a freeze can go unnoticed, and it needs to be fixed in person (so no possibility to remotely fix by night for example), so a lot of time can eventually be lost.  What I am looking for:   a way to detect freezes on Windows (7 x64). Is there any standard method? either kill the root of the freezes, or if not possible reboot the computer. Is it possible to detect the root of a freeze? Is it possible to (not physically) force reboot even during a freeze?   The end goal is that in case of a freeze, current computations might be lost but the computer will become available again ASAP (eg, for remote access to relaunch the computations).  My guess is that for such a program to work, it would need to run in ring0, above pretty much everything else, as to not get caught in the freeze (but that's a bet, I'm not sure if the freezes won't impact the ring0, but the freezes I target still allow for inputs to work like mouse and keyboard, so I guess ring0 might work too).  Constraints:   Very restrictive network security measures (no outside access, only inside computers can access the outside, eg, only UDP hole punching works for remote computer access), so using a remotely controllable internet plug is impossible for example. No hardware change: I can plug additional hardwares to my computer, but I cannot modify the components already inside (eg, cannot change the motherboard, but can plug a PCI device or SATA or whatever).   For the moment, I am looking either for a software that can do this, or for technical information about how to do this myself (and if this might work or if that's just not possible), or any other solution that fits the constraints above.  I do not expect to fix every kinds of freezes using only a software solution, but I hope to at least workaround the type of "partial" freezes where the mouse and keyboard still work.  Thanks in advance.  NOTE: I am talking about non-BSOD freezes here. For BSOD freezes, Windows provide a setting to automatically reboot after kernel dump.

I use a remote desktop program (usually ) to connect to a Windows machine everyday. The remote computer has a fixed IP address, and if the computer is on and responsive, I can access it and even reboot the computer remotely if necessary.  Unfortunately, if the remote computer freezes (for example, if it gets a blue screen), as far as I know, I can't use a remote desktop solution to restart it. Similarly, if my computer is off, I can't use remote desktop to boot it.   I know that one solution is to ask somebody who is physically near the computer to press the reboot or power on button, but I am opening this thread because I am interested in solutions that do not require the physical presence of people to turn on or reboot a remote frozen computer.  Is this possible? If so, what are my options?


Boiled down to the core as I understand it:     A cryptographic algorithm has  if it's unbreakable, even if an adversary has unlimited computational power / time.   If my understanding is correct then cryptographic algorithms like RSA / Diffie-Hellman are not considered to be provable secure since they would be broken to an adversary with unlimited computational power / time.  The only classical algorithm I know of that behaves in this manner is the . I'm specifically asking about classical algorithms because I know that there exist quantum cryptographic algorithms that are provable secure, i.e. .  My questions are:   Is my understanding of provable security correct? And if so, are there any other classical algorithms that are provable secure?

I read the book "Introduction modern cryptography". It gives the notion of computational security of private-key encryption at first which comes from perfect security and statistical security.     Let $(E,D)$ be an encryption scheme that uses $n$-bits keys to encrypt $l(n)$-length messages. $(E,D)$ is computationally secure if    $$E_{U_{n}}(x_{0}) \approx E_{U_{n}}(x_1)$$   And then it introduces the secure game (e.g. CPA, CCA)? I think it is a part of provable security.  "Unconditional security" (or "information-theoretic security" or "perfectly secrecy") and "computational security" are two opposite classes of security. But I do not think "computational security" and "provable security" are two independent classes of security. I know that computational security emphasizes the power of attacker is bounded (polynomial-time algorithm). And the provable emphasizes the mathematical assumptions or cryptography primitives. But it also related to the computational power.


I am stuck at some problem.   I have two lists in python as   >>> List1 = ['a','b','c','d']  >>> List2 = ['0','1','2','3']   I want to merge these both the lists into a dictionary  as  >>> Dictionary = { 'a':'0', 'b':'1', 'c':'2', 'd':'3'}

Imagine that you have the following list. keys = ['name', 'age', 'food'] values = ['Monty', 42, 'spam']  What is the simplest way to produce the following dictionary? a_dict = {'name': 'Monty', 'age': 42, 'food': 'spam'}


My project looks like this: include/util/safety.h include/opcodes/8bit_load_opcodes.h include/CPU.h src/util/safety.cpp src/CPU.cpp src/main.cpp src/opcodes/8bit_load_opcodes.cpp CMakeLists.txt  With the CMake script below cmake_minimum_required(VERSION 3.17) project(gameboy) enable_testing()  FIND_PACKAGE(Boost 1.65.1 COMPONENTS unit_test_framework REQUIRED)  if(NOT Boost_FOUND)     message(FATAL_ERROR "Boost Not found") endif() set(CMAKE_CXX_STANDARD 20) INCLUDE_DIRECTORIES(${Boost_INCLUDE_DIR})   INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/include) INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/include/opcodes) INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/include/util)  ADD_LIBRARY(cpu_util src/util/safety.cpp)  ADD_LIBRARY(cpu src/CPU.cpp src/opcodes/8bit_load_opcodes.cpp)  TARGET_LINK_LIBRARIES(cpu ${Boost_LIBRARIES}) TARGET_LINK_LIBRARIES(cpu cpu_util)  add_executable(gameboy src/main.cpp)  TARGET_LINK_LIBRARIES(gameboy cpu)  When I run make I get: Scanning dependencies of target cpu_util [ 14%] Building CXX object CMakeFiles/cpu_util.dir/src/util/safety.cpp.o [ 28%] Linking CXX static library libcpu_util.a [ 28%] Built target cpu_util Scanning dependencies of target cpu [ 42%] Building CXX object CMakeFiles/cpu.dir/src/CPU.cpp.o [ 57%] Building CXX object CMakeFiles/cpu.dir/src/opcodes/8bit_load_opcodes.cpp.o [ 71%] Linking CXX static library libcpu.a [ 71%] Built target cpu Scanning dependencies of target gameboy [ 85%] Building CXX object CMakeFiles/gameboy.dir/src/main.cpp.o [100%] Linking CXX executable gameboy CMakeFiles/gameboy.dir/src/main.cpp.o: In function `main': /home/cedric/Programming/gameboy/src/main.cpp:6: undefined reference to `unsigned short validate_argument<unsigned short>(unsigned short, unsigned short)' collect2: error: ld returned 1 exit status CMakeFiles/gameboy.dir/build.make:106: recipe for target 'gameboy' failed make[2]: *** [gameboy] Error 1 CMakeFiles/Makefile2:154: recipe for target 'CMakeFiles/gameboy.dir/all' failed make[1]: *** [CMakeFiles/gameboy.dir/all] Error 2 Makefile:114: recipe for target 'all' failed make: *** [all] Error 2  Running nm appears to show an empty output: $ nm libcpu_util.a   safety.cpp.o:  Why aren't there any symbols in libcpu_util and how can I fix this make error? For reference: safety.cpp #include <stdexcept> #include "util/safety.h"  template<typename T> T validate_argument(T value, T mask) {     if((value & mask) != value)         throw std::runtime_error("Value outside of mask!");      return value; }  safety.h #ifndef GAMEBOY_SAFETY_H #define GAMEBOY_SAFETY_H  template<typename T> T validate_argument(T value, T mask);  #endif //GAMEBOY_SAFETY_H

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


Every wizard has a wand, but do any carry a backup in case the first one gets broken or disarmed? I could see that being handy for the element of surprise.  Auror: Expelliarmus! Hah! Now you are harmless without your wand. Looks like it'll be a one-way ticket to Azkaban for y– Death Eater: Avada Kedavra! Whew, that was close! Good thing there's no rule that says I can't have two wands!  I also imagine that a wizard might want multiple wands to use their specialities, like owning both an aspen wand for charms and an ebony wand for transfiguration, since each excel in those types of magic. Do any wizards carry around a backup wand like this? Let's assume that they aren't just temporarily holding on to their enemy's wands or using them for subterfuge, they own the wands and intend to use they both indefinitely. And the Elder Wand doesn't count either.

Is there any canon information in Harry Potter that proves one way or another whether a wizard always owns only one wand as a matter of routine?  What I am talking about is a wizard buying and owning one wand and also a second wand (for backup, or simultaneous use, or separate purpose, or ceremonial+work wand), akin to people buying more than one pair of boots, guns or hammers.  A proof would be either canon info showing someone owning 2 wands simultaneously; or a statement showing why that does not happen except in rare exceptions (see below).    NOTE: I am discounting special situations such as winning an extra wand in a duel ala Harry (e.g. the second wand's obtainment wasn't intended/planned), or someone winning a Death Stick from prior owner (in which case it was intended as a replacement wand and not an extra one); or taking another's wand for a time being, ala Voldemort and Lucius Malfoy (since it was more of a "temporary replacement because main wand was useless for the purpose due to paired cores" - far from a normal situation).  Also, I meant wands intended for use - e.g. if Malfoy would have a (imagined by me) collection of rare antique wands, that's as irrelevant as someone having flintlocks in a display case.


I am trying to make a CLI and GUI for a appliaction in which I am using my CLI to perform task and return string for my GUI and give output.  But problem is when I import my CLI it first takes input as it should when it is run from direct CLI, but I do not want it to take input from CLI when running from GUI.  So, for this is there any way from which I can check if the CLI script is run directly or from CLI or is imported in some file and then being run.  this is an example what I did:  cli.py  print("hello CLI run") x=input() def pr(x):     return("this is what you typed = "+x) print(pr(x))   gui.py  from tkinter import * from cli import pr def sb():     c=en.get()     zz=pr(c)     expression.insert(0,zz) win=Tk() lbl=Label(win,text="Hello World") lbl.pack() en=Entry(win) en.pack() sn=Button(win,height = 2, width = 10,text="submit",command=sb) sn.pack() lbl=Label(win,text="Output :") lbl.pack() expression=Entry(win) expression.pack() win.mainloop()   When I run this this asks me to input in CLI first and then give CLI output and then run the GUI

Given the following code, what does the if __name__ == "__main__": do?  # Threading example import time, thread  def myfunction(string, sleeptime, lock, *args):     while True:         lock.acquire()         time.sleep(sleeptime)         lock.release()         time.sleep(sleeptime)  if __name__ == "__main__":     lock = thread.allocate_lock()     thread.start_new_thread(myfunction, ("Thread #: 1", 2, lock))     thread.start_new_thread(myfunction, ("Thread #: 2", 2, lock))


I am trying to type two or three lines using big parenthesis inserting some sentences. I am  using this but it does not work for me.  \documentclass{12 pt}{article}   \begin{document}  \begin{eqnarray} & & (product of (A\times_{c} B) by C)\nonumber\\ & &\times_{c}  D) by E. \end{eqnarray}  \end{document}    I want to use the parenthesis are big not the small usual one.

I have a multi-line equation that I want to have matching sized parentheses. The advice I read online was to use \left( equation \right. \\ left. rest-of-equation \right) . However, this syntax leaves first half of the equation unaware of what is in the second half. For example, if you include a square root term after the break, the second parenthesis will be larger than the opening parenthesis. When you are using the aligned environment to split a long equation this can look somewhat offputting.    Compare the top equation to the bottom one. The parentheses match in size for the bottom equation, but the left hand parentheses for the top one is  noticeably smaller.  Top Code:   \begin{aligned}[t]   \gamma_{\text{u}} + \frac{1}{108}   \left(57\gamma_{\text{er}} \right. &+  38\gamma_{\text{se}}\\ & {}\pm  \left.\sqrt{2601 \gamma_{\text{er}}^2 + 3648  \gamma_{\text{er}}\gamma_{\text{se}} + 1444 \gamma_{\text{se}}^2}  \right)   \end{aligned}   Bottom Code:  \begin{aligned}[t] \gamma_{\text{u}} + \frac{1}{16} \left(9\gamma_{\text{er}}  +  6\gamma_{\text{se}} \pm  \sqrt{49 \gamma_{\text{er}}^2 + 76 \gamma_{\text{er}}\gamma_{\text{se}} + 36 \gamma_{\text{se}}^2} \right) \end{aligned}


I have made my custom space marine chapter, currently I have only a generic apothecary and captain as my HQ. What I wanted to know is if I could use specific HQ units like the imperial fists Captain Lysander or the Whites Scars Kor'sarro Khan in my custom chapter.

I've never played Warhammer. I have a close friend that does. I am looking for a gift to get her for the game.  Is it possible for a Blood Angels squadron to use a character like Sammael from ravenwing? If I were to get her that would it be useful in her game RAW? Also can a 40k 8th edition game, use units from 30k?


I want to looking for information in graduating level. Is there any collection or library which provide students' theses or dissertations of many universities? Googling just find library for each university.

Is there a global/worldwide database of dissertations? If not, how can I access French, German, Italian, etc. dissertations online?


Suppose $p$ is a prime such that $(p-1)/4$ and $(p+1)/2$ are also primes. Show that $p=13$.   I thought about taking $p_1=(p-1)/4$ and $p_2=(p+1)/2$ and proving that there is only one possible case where $p_1$ and $p_2$ are primes simultaneously. Well that is, obviously, the intention of the question. But, I'm not able to do so.  Please Help!!

Suppose $p$ is a prime number such that $(p-1)/4$ and $(p+1)/2$ are also primes. Show that $p=13$.   My approach:   Since $p$ is prime, it is of the form $6k+1$ or $6k-1$. Now if $p$ is of the form $6k-1$ then $(p+1)/2 = 3k$ which is not possible as $3|3k$.   So $p$ is of the form $6k+1$. Now $(p-1)/4 = 3k/2$ so $2\mid k$. So $p$ is of the form $12k+1$. But now, how to prove $k=1$?  Please help!


I have Win10 installed on a m.2 SSD. I bought a new SATA ssd for ubuntu. Should I choose "Install alongside Win10" or "Erase and install Ubuntu" for the new SSD?

I'd like to see the full How-To on how to use manual partitioning during Ubuntu installation. The existing guides (at least those I found here) cover only automatic part and leave untouched the manual part (or extremely short and contain no pictures).  I'd like to cover such situations:     If your disk contains other systems:


$V$ is an inner product space of finite dimension over $\mathbb{R}$, and $T:V\to V$ a linear transformation which is normal, that is, $T^*T=TT^*$. In addition $T^2=T$.  Prove $T$ is self adjoint, that is, $T=T^*$.  I tried to prove it algebraically by using the inner product but it didn't work for me. Then I tried to prove the statement that $T$ is self adjoint iff $\langle v,Tv\rangle$ is real for all $v$.  I know that $T$ is diagonalizable, therefore there is a basis of $V$ consisting of eigenvectors. In addition every eigenvector of $T$ is an eigenvector of $T^*$. Can I prove that $\langle v,Tv\rangle$ is real only for the vectors in the basis and then it means it is for all $v$?   Any help or further hints are very appreciated.

I have been trying to solve this problem for quite a while. I am still unsure of whether any of the avenues I have pursued have been of any use. Any advice will be much appreciated. Question: Let $V$ be a finite-dimensional inner product space, and let $E$ be an idempotent linear operator on $V$. Prove that if $EE^* = E^*E$, then $E$ is self-adjoint. (This is essentially exercise 5(a) in sec. 80 on p.162 of Paul R. Halmos, Finite-Dimensional Vector Spaces, but Halmos didn't assume that the dimension of $V$ is finite.)


Ok, JavaSE 1.8 running an application in Eclipse Version: Oxygen.3a Release (4.7.3a) Build id: 20180405-1200. Simple arithmetic:   Double dblBalance; ( showing as 2072.41 in debug, but also running the app in the IDE)  Double dblAmountofAllocation; ( showing as 1900.0 at runtime )  dblBalance = dblBalance - dblAmountofAllocation; ( dblBalance shows 172.40999995 at runtime) ( my workaround - shouldn't be necessary) dblBalance = Math.round(dblBalance * 100.0) / 100.0;   I have also tested this in a test case compiled and run from the command line. So it is reproducible. Is it the Java runtime engine?   very puzzled - I would like to know if this can be replicated by others. Most combinations of Double values don't have this problem - do I need to stick with the native data types?

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


I've got a bit of a problem with one of my materials. In the node editor, when I put the image texture straight to the surface output of the mesh it shows up perfectly in the rendered viewport. Same thing when I put it through a diffuse node first. When I add any colour node in the chain it makes the mesh turn completely black. Any reason why this is? It happens with any colour node (Gamma, Hue/Sat, Bright etc.)  There's some photos below of what happens before and after adding a colour node to the chain.  Thanks in advance :)  Before:   After:

I have a project where I reuse the same material for multiple things. So, I use node groups; saves a lot of trouble - at first!  Up to this problem I have with node groups:  In  you can see, that the logo (white text) is on a black background. This black background should be a node group (and certainly not black).    Here is the Logo Overlay node group:    If I put the node group "ultramarinblau" into the Logo Overlay node group, it does not work!  Only if I add the "ultramarinblau"-node group directly into the Logo Overlay node group, it works:    This behavior is not desired. I'd like to reuse my Logo Overlay node group multiple times with a different node group-input.  What am I doing wrong? Or could this be a limitation of Cycles node groups?  Any ideas are appreciated!


For example, William Bank head was the 47nd Speaker of the House for the 74th congress.    Is there a word to describe 47 and 74?

Our numbers have a specific two-letter combination that tells us how the number sounds.  For example   9th 3rd 301st   What do we call these special sounds?


I am trying to write some inline equations in vim-latex, but when I type \(( (To start an equation with a parenthesis), vim replaces it with \\left(  \right)<++>.  What is it doing, and how do I stop it?

I like some of the features provided by the Vim-LaTeX suite, but not all of them.  In particular, I dislike all of the mappings like [[ = \left[ \right] and the automatic placeholder stuff with <++>. I am a very fast typist but with that comes more typing mistakes, which I correct almost instantly by pressing backspace. Unfortunately, if something has automatically added a bunch of place-holders or expanded some expression, I then have to move around the document and remove more characters than necessary. For example, if I accidentally press [ twice, instead of only having to delete one character, I have to delete 10.  Having already looked through the documentation, and some of the source, I have managed to disable some of these "features", but not all of them:  In particular:  let g:Tex_SmartKeyBS = 0 let g:Tex_SmartKeyQuote = 0 let g:Tex_SmartKeyDot = 0   (Turn off maps for backspace, double quote and triple dot.)  let g:Imap_UsePlaceHolders = 0   (Turn off <++> placeholder insertion.)  But I can't seem to find a way of turning off the other stuff. Anyone have any suggestions?  Edit: I was able to "disable" some more things by setting:  let g:Tex_Leader = '`tex' let g:Tex_Leader2 = ',tex'   (Which stops some expansions but still not all. It's not really disabling it but just making it less likely that you're going to type in `texa as opposed to the potentially more common `a, for example.)  PS: Personally, I think it is very poor practice to make an optional package that, when installed, greatly changes the default handling of your system. I don't mind some intelligent source highlighting etc, or some new commands (that don't clobber any old ones), but it seems unhelpful to enable this drastic kind of key remapping by default.


I'm trying to solve the following problem:  Find the recurrent formula for: $a_{n+2}+4a_{n+1}+4a_n=0; a_0=1, a_1=3.$  I would probably want to calculate the first few elements in the sequence, however I fail right at the start. How can I calculate elements when there are $a_{n+2}, a_{n+1}$ and $a_n$ and I only have two numbers $a_0$ and $a_1$ defined?  Thanks for any help

Q1. Find the general solution to the difference equation  $$ a_{n} - 4a_{n-1} + 3a_{n-2} = 6 $$    Q2. Solve the difference equation   $$ a_{n} - a_{n-1} - 2a_{n-2} = 0, a_0 = 2, a_1 = 4 $$    I am completely lost in solving recurrence relation questions. Can anyone guide me in steps to solve the following 2 questions?


Here we see Community's list of accounts. She has 106 communities (does that exclude beta sites?) and has 1 rep on all of them.  But over at her , she only has one account, on Area 51:  I guess it is showing Area 51 because of the strange old code that Area 51 uses, but is is odd that she shows 106 accounts (when there are 138 sites officially) and that she only shows one on the Accounts tab... Why is this, and should it be changed? Is it to do with the new user profile? Update: It's not because of the new profile, this is the image on Stack Overflow. Clicking view more ironically shows less.

(used to show two posts from MSE)   (there used to be a list of the accounts)   (it was there) seems to be fixed


I have only ever asked six or seven questions, but three of them were "unclear" (although I thought them clear enough) and got downvoted once, with the exception of one being downvoted twice. That is a fairly low number. In the Help Center it says "One or two bad questions won't get you blocked". But three? Really? It's impeding my work progress on things I am required by deadline to get done.

If you are reading this, you may have been affected by one of our post quality bans. If so, it is important that you  to understand what has happened and how to regain the permissions that you lost. While trying to ask a question, one could see:  We are no longer accepting questions from this account. See  to learn more.  Likewise, for answers:  We are no longer accepting answers from this account. See  to learn more.   Why am I getting this message? Are deleted posts taken into account too? Is a question/answer ban the same as a suspension? How do I avoid getting a question ban? How long do I have to wait before I can post again? What can I do to release the ban? How can I reactivate my account? Can I simply create a new account? I'll just ask somewhere else on the SE network, and they'll migrate my question to the correct site! Will a ban on one Stack Exchange site affect my standing on other sites in the network? Does this apply to meta sites too? My account is in good standing. Why am I still blocked?


Most people that wear glasses or contacts can squint to reduce the blurriness of their vision.  How can this be explained, and has it ever been used in optics to enhance the focus or clarity of an image?

If you see through small enough aperture, you can see things without glasses.   How does this trick work?


I'm using a lm555 IC in monostable mode. When my input varies from 5v to 0v the output goes from 0v to 5v. But this only happens perfectly if it happens just a pulse at the entrance, in case my input changes from 5v to 0v and continue at 0v for the rest of the time the output does not work correctly. What I want is the following, when my input changes from 5v to 0v and continue to 0v, I want my output to remain high only for the time I have determined.  What I have:    What I need:    I thought I could do that with transistor input, but I did not find a way to do it. If anyone knows something similar thank you.

Can any one help me how to make it when the switch is presed for long time but it will not affect the time delay


I already know what a MPPT is supposed to do. It's basically a buck/boost converter connected to a solar panel that finds the ideal power output by changing (boosting or lowering) the voltage of the panel. That's all well and good, however, this is where I get confused. Once you connect the load to the MPPT, let's say our solar panel voltage gets boosted to 50V, and we then want to charge a car battery with it, which is currently at 12V. Once we connect the MPPT to the battery, the voltage will drop to the battery's 12V...so...why did we boost the voltage in the first place? Is there now more current available now that we're using MPPT since there's more power? Is it the same as just connecting the solar panel directly to the battery?

I'm trying to understand solar panel Maximum Power Point Tracking theory and how it is done practically for charging battery banks.  I think I understand MPPT in a general sense: the solar panel has VI curves which define a specific load in which you will extract the most power. These curves change with environment conditions like light levels, temperature, etc, so the tracking algorithm tries to dynamically find the best load value. It's usually not practical to just change the actual end load that we want to power (and often can't), so we use a switch mode power supply to adjust the output voltage, changing the output current. To balance Pout = Pin (assuming ideal switcher), the panel's current draw changes, and this is how we adjust the operating point on the panel's VI curves.  So my question is this: We are changing the output voltage to get the maximum power, but don't batteries typically need a specific voltage to charge them efficiently? Is it better to shoot for MPP of the solar panel or shoot for optimal charging conditions for the battery?


I created a poll in a Drupal 8 site and I enabled anonymous voting too, but when opening the pool in different browsers/machines, the poll results appear and anonymous users cannot vote. Please tell me where the issue is.

We're having a problem with the core poll module on drupal 7. We have a poll that we want anonymous users to be able to vote on. There is currently one anonymous vote, and now anonymous viewers only see the result (we've tried looking at it from outside our network).   We've checked the perms, and anonymous can vote and view results ( but not change vote). We've cleared the cache.   How does Poll work on D7 with regards to the anonymous user?


I'm practicing on a simple Client / Server connection. The client is supposed to send an Int to the server, and the server is supposed to print this int. However, the server encounters a NullPointerException and doesn't print the int sent by the client. Here is my server: package primitives;  import java.io.DataInputStream; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket;  import bytes.Server;  public class DataServer { private ServerSocket serverSocket; private static DataInputStream in;  public DataServer(int port) throws IOException {     serverSocket = new ServerSocket(port);     System.out.println("Server ready at: " + serverSocket);     Socket clientSocket = serverSocket.accept();      System.out.println("New client connection: " + clientSocket);     in = new DataInputStream(clientSocket.getInputStream()); }  public void close() throws IOException {     serverSocket.close(); }  public static void main(String[] args) throws IOException {     Server server = new Server(9000);     int a = DataServer.in.readInt(); // NullPointerException Here     System.out.println(a);     server.close();      System.out.println("closed"); }  }  And my client: package primitives;  import java.io.IOException; import java.net.Socket; import java.io.DataOutputStream;  public class DataClient {      private Socket socket; private DataOutputStream out;  public DataClient(String host, int port) throws IOException {     socket = new Socket(host, port);     System.out.println("Socket ready: " + socket);     out = new DataOutputStream(socket.getOutputStream()); }  public void close() throws IOException {     socket.close(); }  public static void main(String[] args) throws IOException {     DataClient client = new DataClient("127.0.0.1", 9000); // use port configured in the server code     client.out.writeInt(154);     client.out.flush();     client.close(); }  }  Thank you for your help. I've been trying to search for solutions but couldn't find any, therefore I am sorry if there is a solution that is easily available or if this question has already been asked.

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?


Chlorophyll being green means it absorbs light in the red and blue area of the spectrum. Isn't this the high and low energy light? Wouldn't plants get more energy if they absorbed light in the green area of the spectrum instead of the red one?

I know plants are green due to chlorophyll.  Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light has more energy than red light.  Is there no alternative to chlorophyll? Or is it something else?


I use Firefox ESR 24.2. I log in to Stack Overflow using the Yahoo login. Previously, I used to get a logout option after logging in. Nowadays I do not get a logout option. What should I do? Is it normal?

Since the new top bar has been rolled out - a number of different people, established and new users alike, have asked questions on where a specific link has disappeared to with the new top bar design. Where has the link to <X> gone?


This might seem a bit of a weird question, but when I have sections in a book along with images, the text always seems to spread out throughout the page. Putting \vfill at then end of the page does the trick, but I don't want to have to do that repeatedly.  I can't seem to make a working example and I don't want to copy the code directly from my book for privacy reasons. But if anyone else has had this problem, it would be a great help to figure out a way to have some command which automatically ends every page with \vfill, as that fixes my spacing problem in books.  EDIT. Actually, here's one I don't mind sharing:. This is one case where the spacing becomes too spread out. IF I put \vfill at the bottom, it improves the appearance. But I prefer to always have the code at the top of the page, with the spacing I provided it in my code.

I sometimes get annoying weird spaces in my latex and I dont know how to fix them. these are my global variables. I cannot paste my code unless someone tells me how I can convert all text into random characters. Using this template   \documentclass{article} \usepackage{spconf,amsmath,graphicx} \usepackage{tabu} \usepackage{subfig} \usepackage[usenames, dvipsnames]{color}   the texts that give error. I am not using any functions or local variables. They are all texts.  Many lines of text. LIDAR sensors that provide a 3D map of the environment around the vehicle are unequivocally more powerful than a single stereo-pair.  Despite these attractive features, the use of LIDAR sensors are still...  \begin{figure}[t]     \centering     \includegraphics[width=\columnwidth]{res}\\     \caption{The workflow of our object proposal algorithm.}     \label{fig:workflow} \end{figure}  Many lines of text. Here, we briefly review works that will be used as a baseline for comparison.  In the Selective Search (SS) algorithm \cite{selectivesearch}, pixels analyzed


I need to change my bibliography name in "Bibliografia essenziale", I have tried that but it doesn't work \documentclass[a4paper, oneside, openright]{article} \pdfpagewidth\paperwidth \pdfpageheight\paperheight \usepackage[utf8]{inputenc}  \usepackage[italian]{babel} \usepackage[T1]{fontenc} %usepackage{lipsum} \usepackage{lmodern} \usepackage{graphicx} \usepackage{indentfirst} \usepackage{amssymb} \usepackage{amsmath}  \usepackage{latexsym} \usepackage{amsthm}  \usepackage{caption} \usepackage{eucal}  \usepackage{eufrak}  \usepackage[hidelinks]{hyperref} \usepackage{verbatim} \usepackage{mathtools} \usepackage{mathrsfs} \usepackage{enumerate} \usepackage{pgfplots} %\usepackage{lipsum} \usepackage{wrapfig} \usepackage{float} \usetikzlibrary{intersections} \tikzset{point/.style={insert path={node[circle,inner sep =1.5 pt,fill]{}}} } \usepackage{listings} \usepackage{color}  \theoremstyle{plain}  \newtheorem{thm}{Teorema}[section]  \newtheorem{cor}[thm]{Corollario}  \newtheorem{lem}[thm]{Lemma}  \newtheorem{prop}[thm]{Proposizione}   \theoremstyle{definition}  \newtheorem{defn}[thm]{Definizione}  \theoremstyle{remark}  \newtheorem{oss}[thm]{Osservazione} \newtheorem{esem}[thm]{Esempio}  \title{\begin{huge} \textbf{...} \end{huge}} \date{\vspace{-5ex}} \author{...\\ ...}   \begin{document} \maketitle  ...  \vspace{1 cm} \nocite{*} \bibliographystyle{alpha} \bibliography{Bibliografia} \renewcommand{\refname}{Bibliografia essenziale}  \end{document}  This is my file Bibliografia.bib @book {Bhatia,     AUTHOR = {Bhatia, Rajendra},      TITLE = {Matrix analysis},     SERIES = {Graduate Texts in Mathematics},     VOLUME = {169},  PUBLISHER = {Springer-Verlag, New York},       YEAR = {1997},      PAGES = {xii+347},       ISBN = {0-387-94846-5},    MRCLASS = {15-02 (47-02)},   MRNUMBER = {1477662}, MRREVIEWER = {R. J. Bumcrot},        DOI = {10.1007/978-1-4612-0653-8},        URL = {https://doi.org/10.1007/978-1-4612-0653-8}, }  Can someone help me?

Is there a way to rename (or do away with the name of) the bibliography page that is output using BibTeX?  If so, is the name dependent on the bibliographystyle, or is it something inherent within the BibTeX functionality?


I append expand a list using operator ' * '.  >>> A = [[0, 0]] * 2 >>> A [[0, 0], [0, 0]]   When I am trying to modify the first element in first list item, it modified the first element in all items of the list.  >>> A[0][0] = 10 >>> A [[10, 0], [10, 0]]   Could you help me explain why? What is the mechanism behind?

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


On Stack Overflow, there was a question with an incorrectly formatted list, which lacked a newline before it and thus came out like this: 1. Hello 2. Something else 3. Goodbye  I changed it to the right formatting by inserting a newline:   Hello Something else Goodbye   And I got the "Edits must be at least 6 characters" error message. Is there an OK way to trick this rule?

I recently came across an  by  which contained a link to a specification that has since been moved. When attempting to edit the link, a change which involved the subtraction of only 4 characters, I ran up against the 6 character minimum requirement.  Ordinarily this would not be an issue. A less experienced poster would likely have other things within the answer that could be changed (). In fact, this seems to be the answer on every meta post relating to this topic (, , etc...).  The problem here, since I don't have 2k reputation, is that BalusC writes excellent answers... with the reputation to back them up. I don't feel there is anything in the post (besides the link) that would benefit from me editing.  What is the standard practice here?   Flag the post and explain my situation in the notes (for someone with higher reputation)? Comment on the post and hope that a) visitors read the comments or b) the OP gets notified and updates their post? Make edits, for the sole purpose of increasing characters, providing no benefit and possibly hurting the quality of the post?   For reference, the EL Specification in the post should be changed to , if someone wants to go ahead and take care of this.


I am new to blender and and not quite sure what info should be included here so please be patient with me.

This is meant to solve this problem once and for all. What is every reason an object isn't showing up in a render or viewport in when using the cycles render engine?


So far I am using grep -E '[aeiou]{2}' /usr/share/dict/american-english. This is giving me two vowels, but I want them to be only vowels in a row, like "tooth", "beer", etc. So I want to use grep to get a word with a vowel, but only if that vowel is followed by the same vowel. Like, I want to find tooth, I want to see if I can write a command that will look for the first o and see the next character is a o. Is that more clear? What am I missing?

I am looking for a regular expression that finds all occurences of double characters in a text, a listing, etc. on the command line (Bash).  Main Question: Is there a simple way to look for sequences like aa, ll, ttttt, etc. where one defines a regular expression that looks for n occurences of the same character with? What I am looking for is achieving this on a very very basic level. On the command line. In a Linux Shell.  After quite some research I came to the following answers – and questions resulting from them, thus they just gave me a hint where the solution might be. But:  a) (e)grep and the backslash issue   grep 'a\{2\}' looks for aa egrep'a{2}' looks for aa   Question: Is the necessity of setting backlashes really bound to the command I use? If so, can anyone give me hint what else is to be taken into account when using (e)grep here?  b) I found  for my question, though it isn't exactly what I was looking for:  grep -E '(.)\1' filename looks for entries with the same character appearing more than once but doesn't ask how often. This is close to what I am looking for, but I still want to set a number of repeatings.  I probably should split this into two or more questions, but then I don't want to flood this awesome site here.   P.S.: Another question, possibly off topic but: is it in, inside, at or on the shell. And is on the command line correct?


Joe said, "You're awesome."  "Why thank you," Mel replied.  Should there be a comma after "Why"?

When beginning a sentence with "well", do you put a comma after it?         Well, you know I was wrong.    Well you know I was wrong.


Let's say I have a normal function:  function coolsecretalgo() {     return 42; }   I tought of hiding it's code by using this function:  function hide(fname) {     var fn=self[fname]     Object.defineProperty(fn,"toString",{"value": ()=>fname+"() { [native code] }"})     Object.defineProperty(fn.toString,"toString",{"value": ()=>"toString() { [native code] }"})     Object.defineProperty(fn.toString.toString,"toString",{"value": fn.toString.toString}) }   Is there any way to unhide such hidden function?  hide("coolsecretalgo") undefined coolsecretalgo ƒ coolsecretalgo() { [native code] } coolsecretalgo.toString ƒ toString() { [native code] } coolsecretalgo.toString.toString ƒ toString() { [native code] } coolsecretalgo.toString.toString.toString ƒ toString() { [native code] }   Are there better ways to do it?  I mean: is it possible to write a function like:  function unhide(funcname) { ...some code.. }   and then  unhide("coolsecretalgo")   and get back the original code?

I want to make a JavaScript application that's not open source, and thus I wish to learn how to can obfuscate my JS code? Is this possible?


I just bought a reserved EC2 instance. I can see it under the EC2 management console. But under the running instances i can't see any EC2 instance. How can i launch the reserved instance that i just bought ?  This is the running instances tab

I have an RDS instance running of type db.t2.small.  I bought a reserved instance for 1 year of the same type, I paid the partial upfront rate.  Do I need to assign this subscription in some way to my existing instance to say 'This is the instance that is using the subscription' or does AWS just charge for the instance usage depending which instances you have running and whether an available subscription was active for it at the time which determines the running rate?  The reason that I ask is that I can't see any mention of the reduced rate on my AWS Billing area and it shows that I've used 17 hours of my reservation, but there isn't a row on my bill so far this month that indicates the new partial upfront rate that I should be charged for my instance.


Background   hopefully (adverb): in a hopeful manner Presumably (adverb): used to convey that what is asserted is very likely though not known for certain. While fully acknowledging, as noted in , that hopefully is accepted in standard usage as a sentence modifier and as a ; I wonder about the etymology and more precise historical differences in the usage between hopefully and presumably.    Question based on background  Why is it correct to say:     "Presumably it is true..."      and incorrect to say       "Hopefully it is true..."    In other words, why would the latter sentence be corrected to:       "I am hopeful that it is true..."    which does not mean the same thing;  whereas the former could be changed to:     "I am presuming it is true..."   which does mean the same thing?    Put one other way, why is it standard (and I believe acceptable) English to assume an implicit verb when using presumably:      "I think presumably that it is true..."   where presumably is modifying the verb think to mean that the thought is one which is thought presumptuously or in a presuming manner.    Yet it is not accepted that "I think" is assumed as in:     "I think hopefully that it is true..."   Where hopefully is modifying the verb think to mean that the thought is one which is thought hopefully or in a hopeful manner.  Or is it the case that presumably is just as frequently misused as hopefully and that both are incorrect? If that usage of presumably outlined above is accepted as grammatically correct, is there some etymological reason for this usage?  Presumably someone must know the answer to this question. I await members' replies hopefully.

I said, "Hopefully, I will get better" to a friend and he said that I was using it incorrectly, stating that  is an adverb meaning "full of hope" that modifies a verb. It sounds right, but I'm pretty sure that this usage of hopefully has become prevalent enough to be accepted for this use case. Am I right, is he right, or are we both right?


Quite simple. I have a blur() event handler that fires a function, I want the function not to fire when the blur is triggered by the click on a certain element.  I tried document.activeElement but i get a HTMLBodyElement instead of the element I click on.  code:  $j(".input_filtrare_camp").blur(     function(event) {     nr_img = this.parentNode.id.split("_")[1];     //alert(document.activeElement);     if(document.activeElement.id.indexOf("img_exact") < 0) //run only if the id of the element I clicked on doesn't contain "img_exact"         enter_input_filtrare(event.target);                                                                          });   the alert is for troubleshooting, of course.   I used techfoobar's solution as follows:  var currElem = null;  $(document).mousedown(function(e) {     currElem = e.target; });  $j(".input_filtrare_camp").blur(     function(event) {     nr_img = this.parentNode.id.split("_")[1];     if(currElem.id.indexOf("img_exact") < 0) //run only if the id of the element I clicked on doesn't contain "img_exact"         enter_input_filtrare(event.target);                                                                          });   Check out PointedEars' answer for some important information regarding this issue.

Suppose I attach an blur function to an HTML input box like this:  <input id="myInput" onblur="function() { ... }"></input>   Is there a way to get the ID of the element which caused the blur event to fire (the element which was clicked) inside the function? How?  For example, suppose I have a span like this:  Hello World   If I click the span right after the input element has focus, the input element will lose its focus. How does the function know that it was mySpan that was clicked?  PS: If the onclick event of the span would occur before the onblur event of the input element my problem would be solved, because I could set some status value indicating a specific element had been clicked.  PPS: The background of this problem is that I want to trigger an AJAX autocompleter control externally (from a clickable element) to show its suggestions, without the suggestions disappearing immediately because of the blur event on the input element. So I want to check in the blur function if one specific element has been clicked, and if so, ignore the blur event.


I'm currently working with PostgreSQL and CartoDB to display X and Y coordinates converted to a geom. My shp files have been created and are displayed through CartBD.  When I try and run a map view, the points are displayed in relation to each other accurately, they're simply in the wrong position on a global map.    As you can see in the image, the points are there, but they should be within the bounds of Washington DC. The SRID's I have used are 4326, 2248, 2804, and 2893.  Some example points are below:   "blocksiteaddress" | "blockxcoord" | "blockycoord" "2516 - 2599 BLOCK OF NAYLOR ROAD SE" | "402548" | "133051" "10 - 199 BLOCK OF DANBURY STREET SW" | "399075" | "128889" "1700 - 1799 BLOCK OF I STREET NW" | "396480" | "137054"   Is there a method for obtaining or deciphering what ESRI/SRID code would best fit my data?

I'm working on a school project. I have  from Sacramento, California   I want to convert the XY coordinates to latitude and longitude, in order to import it into tableau and use its mapping features.   I also have the address, if that makes it easier.  I have about 10,000 records, so I need a powerful tool to perform this conversion.


I have to validate a contact form sent from my site. Contact number is set as follows : +0 (000) 000-00-00  Which RegEx i should use for this form validation? This one is not correct: var phoneReg = /^\+\d\\(\d{3}\))\d{3}-\d{2}-\d{2}$/ Thank You

I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant.


What is the correct regalia to wear in the United States when you receive a Masters degree but you have previously earned a doctorate. (And you own your doctoral regalia ) I.e. you’re a physician and you’ve earned a masters in anthropology for fun/enrichment Would it be appropriate to wear your doctoral robe? Masters robe?

I already have a PhD, but now I'm graduating with a Master's in another field from another university.  Question:  What academic robes do I wear?  I know it is normal to wear the regalia from the highest award but that seems strange in this case.


I often come across sentences such as, "Our program assists, at no cost, students maintain independent living..." I believe it should be written as, "Our program assists, at no cost, students to maintain independent living..."  Input?  This isn't a question about the word "help" - this is specifically about the word "assist."

I just recently came across "assist someone do" searching Google for examples to my previous question, and would like to check with you whether it is an acceptable option to "assist someone to do (or "in/with" doing)", or a snapshot of language in transition -- analogous with "help someone do" -- that I caught here.  Please consider the following examples for this:     NAFDAC is to assist you do your business right.      Our company will assist you do your assignments...      (Go down to bottom of page and look up "Transtec Inc.,    Robert Rasmussen PE") We are a specialty engineering company with award-winning expertise in pavements and pavement materials. We can assist you do your job better.


Trying to get a better understanding of the relation between a SU(N) Yang Mill theory and its number of "color" .  Most of the description I've found so far are either way to complex/specific. Yiannis answer on  is almost what I'm looking for, except I was hoping someone could provide addition sources and readings corresponding precisely to what he is describing.

The $\mathrm{U(1)}$ QED case has two physical degrees of freedom, which is easy to understand because the free electromagnetic field must be transverse to the direction of propagation. But what are the physical degrees of freedom the $\mathrm{SU(N)}$ Yang-Mills theory?   I believe that the $\mathrm{SU(N)}$ Y.M. theory has four degrees of freedom, and it is easy to see that by gauge fixing (such as the Lorentz condition or the Coulomb condition) that we can always remove one redundant degree of freedom. But then we still haven't completely fixed the redundant degrees of freedom. Thus my question is:     How many physical degrees and how many are redundant degrees of freedom does the Y.M. theory have?    I would be interested to understand how we can determine this mathematically, and also to understand what the physical intuition behind this is?


The tool to move multiple messages into a different chat room also invites all users that particpated into that new room. Which does make some sense if you want to continue the discussion there, but it is absolutely counterproductive if I'm moving messages because I want to get rid of the entire discussion and just put the whole mess somewhere where it doesn't draw any attention.  I think the move tool has some potential as a tool for moderating chat, but the automatic invitation of users makes it useless for this purpose and because I didn't think about this rather obscure feature I just invited a whole bunch of people to a discussion I wanted to archive quietly.  Please just make this invitation feature optional, and off by default. Though the ability to silently move should be restricted to moderators, and not be available to room owners.

Every time we move people's messages to some recycle bin/trash can room, they're invited to this room, thus leading to sarcastic comments such as . Should these invitations be disabled? I haven't seen any useful situation for those invitations when moving a message. If you think there are useful cases, could there be some special rooms where people are not invited? Like "Recycle bin" or "Trash can".


I have a method, which search in an ArrayList what contains objects with two private fields. Here is the method:      public int searchContactName(String name){      int foundIndex =-1;     for(int i = 0; i < contacts.size(); i++){         if(contacts.get(i).getName() == name){             foundIndex = i;         }     }      return foundIndex; }   It's work well if I use it like this:  searchContactName("xyName");   But if I try to use it with a scenner.next() like thins, for the same name  String name = scanner.next(); searchContactName(name);   It's give me -1. I don't understand, I need to format some way the input? It is the same type or it is different some way if I use the scanner?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Let $a,b,c$ are nonnegative real numbers such that $a^2+b^2+c^2=1$. Prove the inequality $$\frac{a}{1+a^2}+\frac{b}{1+b^2}+\frac{c}{1+c^2}\le\frac{3\sqrt3}{4}$$  I tried the method of Lagrange multipliers and Jensen's inequality but I have not been proved this inequality

Prove this inequality, if $x_1^2+x_2^2+x_3^2=1$: $$ \sum_{i=1}^{3}\frac{x_i}{1+x_i^2} \le \frac{3\sqrt{3}}{4} $$  So far I got to $x_1^4+x_2^4+x_3^4\ge\frac{1}3$ by using QM-AM for $(2x_1^2+x_2^2, 2x_2^2+x_3^2, 2x_3^2+x_1^2)$, but to be honest I'm not sure if that's helpful at all.  (You might want to "rename" those to $x,y,z$ to make writing easier): $$ \frac{x}{1+x^2}+\frac{y}{1+y^2}+\frac{z}{1+z^2} \le \frac{3\sqrt3}4$$


After windows failed to install, I was left with my partition, which bootcamp was supposed to remove but it froze and I exited it (probably not the brightest idea ever). So now I have these extra partitions and I'm trying to merge them back into my main disk, like how it was before the windows installation.   I've tried looking online at what to do but the (-) option that most sites seem to suggest using is greyed out, and would highly appreciate anyone who could help me.   I've attached screenshots of my disk information. I have the 2017 iMac, with Mojave installed.

The startup disk cannot be partitioned or restored to a single   partition.      The startup disk must be formatted as a single Mac OS Extended   (Journaled) volume or already partitioned by Boot Camp Assistant for   installing Windows.   I had installed Windows 10 via bootcamp in my mac. Current version is 10.14.1  Now I don't want windows and need that space back but getting above error when I go bootcamp to remove it.  This is the output of diskutil list  /dev/disk0 (internal, physical):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      GUID_partition_scheme                        *251.0 GB   disk0    1:                        EFI EFI                     209.7 MB   disk0s1    2:                 Apple_APFS Container disk1         181.3 GB   disk0s2    3:       Microsoft Basic Data BOOTCAMP                60.3 GB    disk0s3    4:           Windows Recovery                         509.6 MB   disk0s4  /dev/disk1 (synthesized):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      APFS Container Scheme -                      +181.3 GB   disk1                                  Physical Store disk0s2    1:                APFS Volume Macintosh HD            116.4 GB   disk1s1    2:                APFS Volume Preboot                 44.6 MB    disk1s2    3:                APFS Volume Recovery                512.8 MB   disk1s3    4:                APFS Volume VM                      4.3 GB     disk1s4   And this is of diskutil cs list  No CoreStorage logical volume groups found   Can anybody please help me to solve this problem?  Output after I tried commands given in the first answer  ❯ diskutil list /dev/disk0 (internal, physical):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      GUID_partition_scheme                        *251.0 GB   disk0    1:                        EFI EFI                     209.7 MB   disk0s1    2:                 Apple_APFS Container disk1         250.8 GB   disk0s2  /dev/disk1 (synthesized):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      APFS Container Scheme -                      +250.8 GB   disk1                                  Physical Store disk0s2    1:                APFS Volume Macintosh HD            116.4 GB   disk1s1    2:                APFS Volume Preboot                 44.6 MB    disk1s2    3:                APFS Volume Recovery                512.8 MB   disk1s3    4:                APFS Volume VM                      3.2 GB     disk1s4


I just installed the basic Linux CentOS 7 (no desktop) and am experimenting with the system. Every time I make a mistake (entering things that the command line doesn't like), the computer beeps and it's driving me crazy.   What do I type in the command line to stop this annoying beep?  [root@localhost /]# #what should I run here?

How to disable system beep on Linux? I don't have superuser powers so I cannot recompile kernel/unload module.


I am to find the limit of  $$\lim_{x \to - \infty} \left(\frac{4^{x+2}- 2\cdot3^{-x}}{4^{-x}+2\cdot3^{x+1}}\right)$$  so I used: $$\lim_{x \to -\infty} = \lim_{x \to \infty}f(-x)$$  but I just can't solve it to the end...  Please show me all steps, or at least most of them, so I'll know how to solve it. Thank you.   This question was posted on: , and got 3 answers, but I still don't know how should I solve it, because when I try to solve it (with help of those 3 answers) I get : $$0−12/0$$ every time and that goes to minus infinity...


is there any difference between these two words?  I understand that people often use "food waste" to talk about the issue of throwing away too many cooked food  However, it seems to me that it would be more accurate to describe it as "food wastage".  Another interesting point is about an implicit connotation.     Dictionary.com states that: Waste and wastage are to some extent interchangeable, but many people think that wastage should not be used to refer to loss resulting from human carelessness, inefficiency, etc: a waste (not a wastage) of time/money/effort etc   however, when I refer to another book or, such connotation is not acknowledged.     the Guide to English Usage states that: wastage = act or process of wasting; whereas waste  = unused remnant.   Can anyone explain to me the difference regarding the two words?

I previously worked in a bookstore and at around this time of the year, we did an inventory of the bookstore, counting our stock and shipping back old stock to corporate. There was a term we used to describe what happened when there was a difference between our computer stock read as and what we actually had on-hand in the store. This  term essentially meant "unanticipated loss of stock due either to theft, misplacement, or other reasons." What was this word?


I just want to know how much magnification there is... if I have a point and shoot camera and it has 10X zoom, I'm seeing that the subject is "brought" 10x closer.  So, what does a dSLR telephoto lens need to be to bring the subject 10X closer?  I am looking to buy a 55-200mm Sony lens - will the subject be approximately 10x closer? Or 5x closer or 15x closer?

What is the rule to convert the 'mm' notation to the 'optical zoom' notation? I searched a bit and found this one:  optical zoom = maximum focal length / minimum focal length   For example a 18-55mm lens would have a 3x optical zoom, and a 18-200mm lens would have a 11x optical zoom. Is that right?


Mathematically, you find that the wave function of a particle $\Psi (x,t)$ moves with the same velocity as the velocity of the particle ($v_{particle} = v_{group}$).  Is there a reason why the particle velocity should not equal the phase velocity?

In quantum mechanics, what is the difference between  and  of matter wave? How can it also be that phase velocity of matter wave always exceeds the speed of light?


I would like to split a bibliography such that all references up to a point are listed in the first bibliography and all references that are listed from that point and are not listed in the previous bibliography be listed in the second bibliography. I have gone through many of the questions  but have not found a sufficient answer that I understood. In my series of attempts, I've come up with:  \documentclass[a4paper]{article}  \usepackage[style=nature,backend=bibtex,defernumbers=true]{biblatex}  \usepackage{filecontents} \begin{filecontents*}{\jobname.bib} @article{refAOnly,   author = {Author, A.},   year = {2001},   title = {Alpha},   journal={My Journal}, } @article{refBOnly,   author = {Buthor, B.},   year = {2002},   title = {Blpha},   journal = {My Journal}, } @article{jointRef,   author = {Cuthor, C.},   year = {3003},   title = {Gamma},   journal={My Journal}, } \end{filecontents*}  \addbibresource{\jobname.bib}  \begin{document}  \section{Main text} %\begin{refsection} %\input{textA} This is section A. This represents the main body of the text. Here I cite a unique reference \cite{refAOnly} as  well as a joint reference \cite{jointRef}.  % here I would like to see refAOnly and jointRef listed \printbibliography  %\end{refsection}  \vspace{10mm}   \section{Online only} %\begin{refsection} %\input{textB} This is section B. This represents an appendix. Here I cite a unique reference \cite{refBOnly} as  well as a joint reference \cite{jointRef}.  % here I would like to see refBOnly listed with the number 3 \printbibliography %\end{refsection}  \end{document}   As written, this gives me two full bibliographies. Using refsection doesn't work, as jointRef appears in both bibliographies. I don't want to go through (and change) my bib file as it's used in multiple tex files. I would prefer not to use biber, as that involves switching settings in the environment on multiple computers and back again for other projects, but will resort to it if need be (assuming it helps).  Is there a simple (haha) way to achieve this?

I'd like to have two lists of references in my document.  However, I want each reference to appear only once in the entire document.  \documentclass{article} \usepackage[backend=biber,defernumbers=true]{biblatex} \bibliography{foo} \begin{document} \begin{refsection}  \section{Previous Track Record} I am an acknowledged authority on aardvarks \cite{mynature}. \printbibliography[prefixnumbers=A,heading=subbibliography] \end{refsection}  \section{Research}  \begin{refsection} I will use the methods developed in \cite{mynature} to address the questions raised in \cite{other}. \printbibliography[heading=subbibliography] \end{refsection}     \end{document}   Here are the contents of foo.bib:  @article{mynature, author={Ego Sum}, journal={Nature Soundbites}, title={Aardvarks are artistic}, year={2013} }  @article{other, author={Tu Es}, journal={Gnu Letters}, title={Gnus gnaw gnomes}, year={2014} }   In the two bibliographies, I only want the paper in Nature Soundbites to appear once, and be cited in both places as [A1].  Any suggestions welcome!


I'm running Ubuntu 18.04 on VirtualBox. I am trying to run a shell script that launches multiple mongo instances. I want the script to run after the system reboots but before login  I have added the following line in my /etc/profile file -   /bin/sh /home/dimension/data/scripts/run_mongo_instance.sh   The shell script has the following permissions  dimension:~$ ls -lh data/scripts/run_mongo_instance.sh  -rwxrwxr-x 1 root root 313 Oct  4 17:30 data/scripts/run_mongo_instance.sh   Here are the contents of the file -  nohup mongod --config /home/dimension/data/config/archive/archive.conf &  # ReplicaSet  nohup mongod --config /home/dimension/data/config/replica/replica2.conf &  nohup mongod --config /home/dimension/data/config/replica/replica1.conf &   I am able to run this file manually by running the following command -   sudo /bin/sh /home/dimension/data/scripts/run_mongo_instance.sh [sudo] password for dimension:  nohup: appending output to 'nohup.out'   Corresponding output -   dimension:~$ ps -ef|grep mongo  mongodb    953     1  2 10:01 ?        00:00:30 /usr/bin/mongod --quiet --config /etc/mongod.conf root      3614  2441  1 10:03 pts/0    00:00:20 mongod --config /home/dimension/data/config/archive/archive.conf root      3615  2441  1 10:03 pts/0    00:00:22 mongod --config /home/dimension/data/config/replica/replica2.conf root      3616  2441  2 10:03 pts/0    00:00:27 mongod --config /home/dimension/data/config/replica/replica1.conf dimensi+  6145  6119  0 10:24 pts/1    00:00:00 grep --color=auto mongo   I have recently upgraded to Ubuntu 18.04. On 16.04 the command was used to run inside /etc/rc.local  How should I make this script work on 18.04?

On previous installed version kubuntu 15.xx i added a line into /etc/rc.local - /home/diet/scripts/my-auto-mount-script which obviously referred to a script that if on home wifi network drives should be mounted.   This worked flawlessly on kubuntu 15.xx  After the upgrade it seems /etc/rc.local is being ignored on boot because running the command /etc/rc.local still seems to do the trick. The reason I think rc.local is being ignored is because the script it refers to should produce logs on script success but also on script fail, but there are no logs.  Can anyone give me some pointers on how to troubleshoot this matter?  PS : yes I know that putting stuff in /etc/fstab is also a way of mounting the drives, but when I'm not at home I hate it that I can see the drives on dolphin and have those little red crosses on them because the are not there. This way when I'm on the road (it is a laptop) people can't see what i have at home.


If I was running a command before the SSH connection was dropped, will the command continue executing?

So, say I get disconnected from an SSH-session after I've started rsync or cp or any other command that can be long running. Does that command keep running until it's finished after I get disconnected or does it just get killed?  Always wondered this.


I'm working on an ASP.NET MVC 5.1 web site, and I need to show a picture if it exists in an ftp server (CDN). Foldername and filename are tied to rules so I know them beforehand. I need to display a message if this file does not exist.  How can I check if this file exists?   does not help since I need to check if the file exists on a remote server and not a local folder.

I need to use FtpWebRequest to put a file in a FTP directory. Before the upload, I would first like to know if this file exists.   What method or property should I use to check if this file exists?


I was preparing several texts in xelatex in Russian, everything was fine. But today I needed to prepare in Ukrainian. Here is an example of a file.  \documentclass[a4paper, openright, 12pt]{extreport} \usepackage[left=15mm,right=85mm,top=15mm,bottom=20mm]{geometry} \usepackage[ukrainian,english]{babel}    %% загружает пакет многоязыковой вёрстки \usepackage{fontspec}                         %% подготавливает загрузку шрифтов Open Type, True Type и др. \usepackage{indentfirst} \usepackage{titlesec,titletoc} \usepackage[final]{microtype}   % -------------- Настраваем шрифты ----------------------------- \setmainfont[StylisticSet=1]{Old Standard}% Основной шрифт текста \defaultfontfeatures{Scale=MatchLowercase}  \selectlanguage{ukrainian} % ================ Настройка некоторых параметров =================| \parindent=25pt %------------------------------Отступ первой строки| % -----------------------------------------------------------------|  \clubpenalty=10000 \widowpenalty=10000 \tolerance=600  \hfuzz=0.2pt %\makeatletter %\renewcommand{\@chapapp}{Розділ} %\makeatother  \overfullrule=1mm \begin{document} \author{Богдан Тертишний} \title{Зимові розповіді}  \chapter{}  Але щоб ви з....  Але ми цураємось....  \end{document}   At compilation I receive an error.      ! Package babel Error: Unknown language `russian'. Either you have   It is unclear why xelatex loads the Russian language?

I've been trying to change the language of my LaTeX document by replacing \usepackage[swedish]{babel} with \usepackage[english]{babel} but I only get this message:  ! Package babel Error: You haven't loaded the option swedish yet.   I've read in an other question at this forum that compiling enough would solve the problem, but that doesn't work for me. Does anyone know what I should do?