I understand from first hand experience that Lead Free solder is more difficult to use than leaded solder. But for a PCB, if I were to use Lead Free solder paste, are there any serious drawbacks using that instead of Lead solder paste? For my application, this is for hobby PCB application. I don't have a curing oven, so I planned on using my hot air station to melt the solder paste. Thanks.

I am sending my first PCB design to Sunstone for manufacture and I need to decide whether to order the board finish lead-free. All of the components are lead-free, and I have not decided on solder paste. There are about 25 chips on the board and the smallest are 0803 and SOT143. The board size is 3.0x1.5 inches. I am planning to order a cheap IR reflow oven like the T962A. This is not a consumer product (it's a driver board for an IR laser used in scientific experiments). I understand that lead-free solder doesn't flow as nicely and requires higher temps, etc. Shoud I Go Green or should the additional usage complexity dissuade me from using lead-free?  Followup question: should I order a stencil for a board like this?


Problem Setup:  We want to show that a group $G$ of order $180$ is not simple. We do this by contradiction.   Thus we first observe that $n_3(G) = 10$, which means that the number of $3-$Sylow subgroups is $10.$ Next, we try to show that the $A\cap B = \{e\}$ where $A\neq B$ and $A,B$ are $3-$Sylow subgroups.  For this, we assume that $g\in A\cap B$ such that $g\neq 1$ then we consider $C(g) =\{h\in G:gh=hg\}.$ Then we can observe that $C(g)$ is subgroup of $G.$   I want to show that $C(g)\supset A$ and $C(g)\supset B$ and that $|C(g)| = 18.$ Apparently this should lead to a contradiction implying that $A\cap B =\{e\}.$  My Attempt:  Here is what I have so far. We know that $A$ and $B$ are conjugates of each other and therefore there exists $y\in G$ such that $A = y^{-1}By.$ Next, if $a\in A$ then in order for it to be in $C(g)$ it must satisfy $ga=ag$ or $g=aga^{-1}$ which implies that  $$y^{-1}gy=aga^{-1}\implies gya =yag\implies ya\in C(g).$$  But I can't see how to work backward and show that $A\subset C(g).$  However, if we assume that $C(g)\supset A$ and $C(g)\supset B$ then we observe that $|C(g)| \in \{9, 18,36,45,90,180\}$ since it contains subgroups of order $9$,  namely $A$ and $B.$ Now $|C(g)|\neq 9$ since that would mean that $C(g) = A=B$ which is impossible. If $|C(g)| = 180$ then $C(g) = G$ but I am not sure why this would cause a problem.   I think to obtain further reduction I will have to use the fact that $|G|$ divides $[G:Z(g)]!$ since otherwise $Z(g)$ would contain a non-trivial normal subgroup [index theorem] which will be a contradiction. So if we have $|C(g)|\in \{18,36,45,90\}$ then I can show using the index theorem that $|C(g)|=18.$ Although, I don't see how this could lead to a contradiction.  Note:  This is different from the question asked  since I am asking a question that refers to a very specific step in the proof that is used to show that the group is not simple. Furthermore, the way that I have to prove this fact is different from the way used there.

What i deduced is that $n_5=1,6$ or $36$. We are done if $n_5=1$.   If $n_5=36$ we $N_G(P)=P$ for any Sylow $5$-subgroup P as $|N_G(P)|=\frac{180}{36}=5$ and $P$ is abelian cyclic so by Burnside p-complement theorem there exist a normal subgroup of order $36$ which is complement to $P$ , fine, and we are done, not simple.  For $n_5=6$, $|N_G(P)|=\frac{180}{6}=30$. From here I can see that by $N/C$- theorem $|N_G(P)/C_G(P)|\le 2$. In this case I am stuck, Any help please.   Thanks in advance!


char* quickrecv(SOCKET* sock) {     int ilen;     char* len = (char*)malloc(4);     recv(*sock, len, 4, 0);     memcpy(&ilen, len, sizeof(ilen));     char* buf = (char*)malloc(ilen);     //no matter what value ilen is, sizeof buf is always 4 when it shouldn't be     recv(*sock, buf, ilen, 0);     return buf; }  Hello everyone!  Bit of a noob question here.  I am creating a simple socket protocol in c++ for fun.  I tried making a receive function for convenience however it is not working.  When I receive the data, it either adds characters to the output to make the output four characters long or it cuts off the output so it is only four characters long.  I did some debugging and apparently my char pointer "buf" is only the size of four bytes.  Even though "ilen" is different every time (I checked with printf), buf ends up only being four bytes of allocated memory. Why is the size of buf only four even though the parameter for malloc is different everytime?  Thank you!

First off, here is some code:  int main()  {     int days[] = {1,2,3,4,5};     int *ptr = days;     printf("%u\n", sizeof(days));     printf("%u\n", sizeof(ptr));      return 0; }   Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)?


The Fibonacci sequence starts with 1, 1, 2, 3, 5, 8, 13, ... .(Start from the 3rd term, each term is the sum of the two previous terms). Let $F_n$ be the $n$th term of this sequence. $S$ is defined as $S=\frac{1}{2}+\frac{1}{4}+\frac{2}{8}+\frac{3}{16}+....+\frac{F_n}{2^n}+....$ Calculate the value of $S$  I have no idea how to solve this, hints aswell as solutions would be appreciated   Taken from the 2013 AITMO

We are familiar with the nifty fact that given the Fibonacci series $F_n = 0, 1, 1, 2, 3, 5, 8,\dots$ then $0.0112358\dots\approx 1/89$. In fact,  $$\sum_{n=0}^{\infty}\frac{F_n}{10^n} = \frac{10}{89}$$  How do we prove that, more generally, for $p > 1$ then,  $$\sum_{n=0}^{\infty}\frac{F_n}{p^n} = \frac{p}{p^2-p-1}$$  (The above simply was the case $p = 10$.)


Is it possible to associate an image with a category in Wordpress? I'm outputting a list of all categories and would like to feature an image alongside each category name.

I couldn't find the solution anywhere else, so I believe is a valid question for this website. I think my problem is divided in two parts. I created a custom taxonomy called "Type" and within it, I have terms (tags) like "cool", "sad", "amazing"..and so on.   1) I want to associate an icon for each one of my terms. 2) I want to display those icons (within link to the term archive) in my front page, like a feature image for each post.  No idea how to do that. Help please.


I bought a plot in Falkreath and finished half of the house and furnished it. I later realised that in the kids room all the bed said they were taken, even thoough I do not have anyone living in the house. I also cannot adopt any children.

I bought two pieces of land. One from Morthal, and one from Falkreath. Morthal was the first plot of land I purchased. I only finished half of it. I bought the plot of land in falkreath because I liked the nature better. I finished the house completely in Falkreath. Every time I try to adopt a child off the streets it keeps saying "I have a place but no room for you" Even though I have the bedrooms in my Falkreath house. Why can I not adopt a child and have him/her live at my house in Falkreath?


I am writing this query to find duplicate CTN Records in table1. So my thinking is if the CTN_NO appears more than twice or higher , I want it shown in my SELECT * statement output on top.  I tried the following sub-query logic but I need pulls     SELECT *          table1     WHERE S_IND='Y'      and CTN_NO = (select CTN_NO                       from table1                      where S_IND='Y'                        and count(CTN_NO) < 2); order by 2

What's the simplest SQL statement that will return the duplicate values for a given column and the count of their occurrences in an Oracle database table?  For example: I have a JOBS table with the column JOB_NUMBER.  How can I find out if I have any duplicate JOB_NUMBERs, and how many times they're duplicated?


if i have two particles in states: |1> and |2> respectavly , and they are not identical then the combined state is |1>|2> ,  but if they are identical then the labels 1 or 2 are arbitrary and could be swapped so supposedly we get two options:   bosons   = |1>|2> + |2>|1> fermions = |1>|2> - |2>|1>   Why there are only these two options ? can't you have any arbitrary superposition of the two states ? (eg: a|1>|2> + b|2>|1> , a*a + b*b = 1)

I have read that fermions cannot exist in the same state simultaneously. I understand why indistinguishable particles with an antisymmetric superposition of states can't exist in the same state simultaneously, but why must fermions have an antisymmetric superposition of states?  The only characterising property I know of fermions having besides antisymmetry is spin, for which they have half-integer. I understand that this is the case simply because particles with half-integer spin and particles with zero or integer spin were defined as fermions and bosons respectively.  My perusal of the Wikipedia page on the  leaves me under the impression that spin has nothing to do with the wavefunction's symmetry properties:     Naively, neither has anything to do with the spin, which determines the rotation properties of the particles, not the exchange properties.   Are antisymmetric wavefunctions simply classified as fermions, in the way half-integer spin particles were? I don't see how this could be the case, as, if spin and symmetry were independent, half-integer spin particles with symmetric wavefunctions (and antisymmetric integer spin particles) would be possible.


So I play Minecraft on a Windows 10 PC, and every time I try to open it, the screen will stay grey and it won't respond. I re-installed it, but that didn't work. Then I went into my .minecraft folder and saw that my launcher_profiles.json was gone. These are the Minecraft profiles, right? I think that's the problem, but I don't know how to get it back. How do I get Minecraft to start again?

Lets say that when you open your Minecraft Launcher you don't see anything and it is all gray. When you click on the launcher it says it is no longer responding and crashes.


The obvious response is $A = B$. But I came up with another response. I can't figure out what's my bias.  Lets say    $S = A - B$ $T = B - A$   Proving $S=T$ means proving $S \subseteq T$ and $T \subseteq S$  Let's start with $S \subseteq T$  For any $x \in S$ :   $x \in A$ $x \notin B$   if $S \subseteq T$, $x \in T$ and :    $x \in B$ $x \notin A$   There is no $x$ giving satisfaction, so $A$ and $B$ are empty.  I prove $T \subseteq S$ by symmetry  My solution is : $A = B = \emptyset$  What's wrong ?

Hello I am taking a Discrete Mathematics course and having some trouble with this question about sets:  Under what conditions is $A- B = B- A$  Diagram:   Diagram:   Maybe I'm understanding incorrectly, but how can A-B and B-A be equal if they contain elements that are not in each other?


Suppose $P(X=1)=P(X=-1)=1/2$ and define   $$X_n=\begin{cases} X\ \text{with probability}\ 1-\frac{1}{n} \\ e^n\ \text{with probability}\ \frac{1}{n} \end{cases}$$  I then need to prove or disprove that $X_n$ converges to $X$ in probability, distribution and quadratic mean.  For the convergence in probability I noted that $P \left( |X_n-X|>\epsilon \right)=P\left( X_n>X+\epsilon \right)+P\left( X_n<X-\epsilon \right)=\frac{1}{n}+0 \to 0$  Assuming then that I got that right, $X_n$ also converges in distribution to $X$ as convergence in probability implies convergence in distribution.  I do not know how to handle the convergence in quadratic mean though. Could I please get some help there? If I can prove convergence in QM, the other implications follow, which makes me think that it won't be the case ;).  Thank you.

Let $\mathbb P(X=1) = \mathbb P(X=-1) = 1/2$. Define       $$X_n = \begin {cases} X & \text{with probability } 1- \frac{1}{n}\\  e^n & \text{with probability }  \frac{1}{n} \end {cases}$$      Does $X_n \leadsto X$ (i.e., converge in distribution)? Does $X_n \stackrel{P}{\rightarrow} X$? Does $\mathbb{E}[(X-X_n)^2] \to 0$?   I think $X_n \leadsto X$ because just by picturing the CDF  as n goes to infinity, their CDFs converge. Can I get some confirmation on this?  But for convergence in probability, I'm having trouble with the limits.   To do this, what I'm trying to do is find $\mathbb P(|X_n-X| \leq \epsilon)$ and then just take 1 minus that as shown on this site:   If $X_n = X$, then $|X_n - X|$ is just $0$ so for all $n$, $|X_n -X| < \epsilon$ But if $X_n = e^n$ then I have the two cases for $X$. For $X=1$, $|X_n-X| = |e^n-1| \leq \epsilon$. and For $X=-1$, $|X_n-X| = |e^n +1| = e^n + 1 \leq \epsilon$. This is where I am stuck. I'm trying to find conditions relating $n$ and $\epsilon$ similiar to here the example on the site. But I'm not sure how to get that from $|e^n - 1| \leq \epsilon$ and  $e^n + 1 \leq \epsilon$ .  Am I even on the right track?


So I'm new to AJAX and I have this code that I'm trying to run. I want it to change the paragraph text by using the content in my contact.txt file, but when I run the code it errors:     "SCRIPT5: Access is denied."   I'm using IE-11 to run the code.  My Code is as follows:  <!DOCTYPE html>
The XMLHttpRequest Object

Let AJAX change this text.
  <button type="button" onclick="loadDoc()">Change Content</button>

Is there local file manipulation that's been done with JavaScript? I'm looking for a solution that can be accomplished with no install footprint like requiring .  Specifically, I'd like to read the contents from a file and write those contents to another file. At this point I'm not worried about gaining permissions and am just assuming I already have full permissions to these files.


We are shooting 9,000 boards a month in China, and want to remove the markings on several keys ICs so our competitors don't know what parts we are using.    I spoke with our IC manufacturers and for custom non-marked ICs, the MOQs are higher than we want, so for now we are looking at a hand process.    Our PCBA shop said they'll remove markings for "free" -- we'll be over in China, in 30 days to babysit the first production run, but we haven't discussed how they are going to remove the markings.  We have 27,000 ICs per monthly production to take off markings.  I've seen Chinese use some kind of electronic friendly glue to obscure IC markings (very thin and watery -- I forget the proper glue term, but like a potting RTV) and they just embed the ICs in glue.  If you try to scrape away the glue, you are left with an IC with mangled markings.  I was thinking light grit sand paper to sand down markings, but I do worry about damaging solder joints on these ICs if you apply to much pressure.    Any recommendations on a good assembly line process to remove IC markings?

In  I asked about ways one might obfuscate the design of a system, to prevent unauthorized cloning. One suggestion was that IC manufacturers are often willing to put custom labels on their chips. The idea is interesting, but my quantities are low enough that this would not be cost-effective. How might one remove or otherwise render unreadable the labels on ICs?


Let be $Y$ the matrix of observations with $n$ lines and $m$ columns.  Let be $X$ the centered matrix, where $X_{i,j} = Y_{i,j} - \overline{Y_{.,j}}$ , $i = 1:n$, $j = 1:m$  Edit : $\overline{Y_{.,j}}$ is the mean of each column  $X^{t}$ is the transpose matrix  What is this matrix $\frac{1}{n-1} X^{t}X$ ?

For a given data matrix $A$ (with variables in columns and data points in rows), it seems like $A^TA$ plays an important role in statistics. For example, it is an important part of the analytical solution of ordinary least squares. Or, for PCA, its eigenvectors are the principal components of the data.  I understand how to calculate $A^TA$, but I was wondering if there's an intuitive interpretation of what this matrix represents, which leads to its important role?


$$\int_{0}^1 (1 + 4y^2)^{1/2} dy$$   So, how do I integrate this without the use of trigonometrical substitution? Can anybody give me a hint? Thank you!

How do we solve (i.e. get the closed form of) $\int \sqrt{1 + t^2} dt$ ?   shows the closed form of it but not the steps in solving it.  I think I need some algebraic trick..   I thought of some hyperbolic functions and their derivatives and equalities:  If I make $ t = \sinh x$, then I can reduce the integral to  $$ \int \cosh ^2 x dx $$ though I'm not sure if this is valid. But from here, I cannot go on evaluating the integral...


As an extension to my last question    This is the EF code I've got which successfully gets all the records from the Person table where DeletedFlag is false  objRecord = await _context.Persons     .Where(tbl => tbl.DeletedFlag == false && tbl.Surname.Contains(theSurname))     .ToListAsync();   I now want to conditionally sort the resultset in either ascending or descending order based on other criteria.   I can add additional code after the above like so   if (sortorder == "asc") {     objRecord =  objRecord.OrderBy(tbl => tbl.Surname).ToList(); } else {     objRecord =  objRecord.OrderByDescending(tbl => tbl.Surname).ToList(); }   which will sort the list and store it back into itself, but wondered if there's a way to add the sort order criteria within the initial call.  EDIT  The "this is a duplicate" link points to a LINQ example that works the way my second code section does  if (sortorder == "asc") {     objRecord =  objRecord.OrderBy(tbl => tbl.Surname).ToList(); } else {     objRecord =  objRecord.OrderByDescending(tbl => tbl.Surname).ToList(); }   which is what I'm trying to avoid  Well read admins!

I have a method which is given the parameter "bool sortAscending". Now I want to use LINQ to create sorted list depending on this parameter. I got then this:  var ascendingQuery = from data in dataList                       orderby data.Property ascending                       select data;  var descendingQuery = from data in dataList                       orderby data.Property descending                       select data;   As you can see, both queries differ only in "ascending" resp. "descending". I'd like to merge both queries, but I don't know how. Does anyone have the answer?


Let $f:(0,\infty)\to \Bbb{R}$ be differentiable and $\lim\limits_{x\to \infty}f(x)=1$ and $\lim\limits_{x\to \infty}f'(x)=b$. Find the value of $b$. I assume $f(x)=\dfrac{x}{x+1}$. I found above is true. But how to prove formally? I wanna prove it by MVT. How to proceed? As given $f$ is differentiable then we can use formula of derivative. But how? Any help will be appreciate.

Given that $f$ is differentiable, what does $\lim\limits_{x \to \infty} f(x) = 1$ say about $\lim\limits_{x \to \infty} f^\prime(x)$ ? Intuitively I feel that it's $0$.  I attempted to solve this by trying to evaluate $$\lim_{x \to \infty} \lim_{h \to 0} \frac{f(x + h) - f(x)}{h} $$ by trying to interchange the limits after showing that $\frac{f(x + h) - f(x)}{h}$ converges uniformly as $x \to \infty$. But I couldn't proceed further.  Trying to work backwards, as a specific example, $f(x) = \arctan(x)$ came to my mind. It's derivative certainly goes to $0$ as $x \to \infty$. Doesn't this show that $\frac{f(x + h) - f(x)}{h}$ converges uniformly to $0$ as $x \to \infty$ ?  I'm totally confused! I would really appreciate if anyone told me what I am doing wrong.


news.puppin.org seems to be scraping right into a wordpress blog, and ranking in searches too. I ran across this link:  http://news.puppin.org/question/non-relational-db-which-one-is-the-right-choice-closed/

of Stack Overflow, all content posted on Stack Exchange sites by their users (i.e. you wonderful people) has been provided to the whole universe under . For my fellow non-lawyers, that license basically means:   Anyone can use any Stack Exchange posts at any time without having to ask for permission Making money off of the copied content is permitted You don't even have to copy stuff from here verbatim; you can just use it as a starting point and make whatever edits you want There are just two rules you have to follow:   You have to provide . Simple links to the original post and author info are just fine. You have to  and allow other people to use your content, as long as they follow these very same rules. How meta!    (If you ever forget any of that, and want to refresh your memory, the license info is linked to in the footer of every page.)  There are, in fact, a lot of people who republish varying amounts of our content for assorted reasons. Unfortunately, there are some Stack Content Republishers Attributing Poorly and/or Excelling at Ranking (SCRAPERs, for short).  In this context, "attributing poorly" means any use that doesn't follow our attribution rules or make any other reasonable attempt at give credit. This can get pretty egregious; I've seen SCRAPERs that not only don't link back to SE originals, but also use fake author info and post dates to make it harder to find originals. By "excelling at ranking," I'm referring to copycat sites that end up higher in Google results than the original SE sites do for the same content. That's not necessarily wrong, but in some cases, it indicates inappropriate SEO hackery.  So, the question is: what can you do if you spot a SCRAPER?


Fairly straight forward question and a fairly common scenario I would imagine. I have taken photos with iPhone and digital camera of the same subjects and locations, most of these groups of photos have been put in folders like "Holiday in Dorset" or "Waterpark".  Is there a way to merge location data from iPhone photos (img*.jpg) to digital camera photos (DSC*.jpg) by folder? I have '000s of photos to do this with, so need to do this in as automated a way as possible. Happy to write batch scripts, just need to know best way to approach the problem and what tools to use.

So i did quite a big trip recently, and took lots of pictures with my DSLR and occasionally Android phone. Only after coming back did i read about the whole GPX file, tracklog options in Lightroom. meaning i don't have such a tracklog file.  The android phone did geotag most photos it took. (at least, when it got a gps fix i guess)  So my question is, is there some software or way that will automatically copy the geotag from the android's photos to photos taken on the same time with my DSLR?  Or alternatively, generate a tracklog from the geotagged data in the android pictures?


I searched on here and I read everything on this page:   But I still don't understand what's going on with my lenses and how they are labeled. I have a couple of lenses, one is labeled as "3.5-5.6/18-55" and I know that means "F-stops from 3.5 to 5.6 and focal length of 18mm to 55mm" but what I don't understand is I can set the aperture to numbers outside that range, regardless of the focal length. For example I can set the camera (Sony Alpha 65) to F/22 and when I shoot the image, it's obviously F/22.  SO, if the labeled numbers are not a limit, what are they for? What is stated on the web page is not correct, where he says "when you zoom out to 18mm you'll be at F/3.5 and when you go in to 55mm you'll be at F/5.6" - because I can be at whatever F-stop I want, at any point along the zoom range.  OK, after posting I found this in the related posts:   That kinda answers my question. So, to be clear, the numbers are the lowest you can go at each zoom extreme?

I made a series of outdoor shots with Nikon D5000, with the 18-55mm 1:3.5-5.6G VR kit lens.  On some shots, I see in the EXIF info f/11, and in another shot, f/9.    How can that be, that the f-number is greater than 5.6, when that's listed as the maximum in the lens spec?


For past month or so, from time to time (every 2-3 days) when starting up Google Chrome I see constant claims that it didn't shut down correctly.    This seems to be a false claim, because:   I always close Chrome with "x" button and always shut down the computer in the standard way. Every time I click on Restore Chrome opens my two startup pages and isn't actually restoring anything.   Where can I find some details about this behavior. Is it fixable? Can I do something to prevent or disable displaying this false warning?  I have recently upgraded my computer from Windows 7 Professional to Windows 10 Pro, but this should have no influence on reported problem, because I've seen this message before the upgrade, on Windows 7 as well.

I am getting "Google Chrome didn't shut down correctly" twice a week - it becomes a very annoying problem -  I always fixed this issue by removing the chrome's default user profile and re-opening the chrome, but doing this will remove all my extensions / apps / bookmarks / settings.   but this is happening more often and I keep losing settings   is there a way to end this madness? I am running Win 8.1 / latest version of chrome


I had a dataset with binary data. I created a logistic regression model with continuous data on the x-axis and binary data that has values 0 and 1 on the y-axis. Then I plotted my model, a line that shows the possibility of belonging to the '1' value on the y-axis. The probability line seems fine, but how can I test the accuracy of this model?

I'm modelling an event with two outcomes, a and b. I have created a model which estimates the probability that either a or b will happen (i.e. the model will calculate that a will happen with 40% chance and b will happen with 60% chance).  I have a large record of outcomes of trials with the estimates from the model. I would like to quantify how accurate the model is using this data - is this possible, and if so how?


I'm trying to get the value of a cell in Google Sheets and show it on a web page (in Wordpress). It appears that you could publish individual cells in the old google sheets but I can't find how to do this now. Any suggestions?

I am a teacher who is trying to create QR codes for book reviews to be placed on books in the library. I have collected all of my students' book reviews via a Google Form, so that their answers are on a Google Sheets (one column, about 100 rows). Instead of creating a QR code from the reviews and limiting the characters for the length, I'd rather have each review be a separate URL and use that address to create the QR code instead. Instead of creating 100+ different web pages or sheets in Google, if there was a way to create a link directly to a specific cell in the sheet that would be incredibly helpful. I tried to use the query formula (limit and offset) after publishing the web page and also not publishing it, but I get an error each time. I tried adding the range/cell using this URL:  but it comes up with the error page saying:  Sorry, the file you have requested does not exist. Please check the address and try again.  I'm not sure if I typed it in wrong or what. The code I used originally was: /gviz/tq?tq=limit 1 offset 32 It actually is working today to give me the limited row, but there are a lot of extraneous characters included (this is the actual link: )  Is there a way (or an easier way) to do this? Is there any way to keep the formatting of the Google Sheet?


Let $G$ be a finite abelian group. Show that there is a Galois extension $K/\Bbb Q$ with $\text{Gal}(K/\Bbb Q) \cong G$.   I have seen one proof using For a ﬁxed positive integer $n$, there are inﬁnitely many prime numbers p such that $p ≡ 1$ (mod $n\Bbb Z)$.   But is there any easy way to prove this? Please reply

I'm trying to prove that every finite abelian group is the Galois group of of some finite extension of the rationals. I think I'm almost there.   Given a finite abelian group $G$, I have constructed field extensions whose Galois groups are the cyclic groups occurring in the direct product of $G$. How do I show that the compositum of these fields has Galois group $G$.  Cheers


Given a number N ( Value can be large like N < 10^9 ) How can we calculate sum of the number of factors of first N numbers??  Example :  For n = 3  Answer:   = #f(1) + #f(2) + #f(3)  ---   { #f(n) -> number of factors of n }     = 1 + 2 + 2    = 5

I have a sequence: $1,3,5,8,10,14,16,20,23,27,\dots$  I know that the recursive relation is:  $$p[i] := p[i-1] + \text{number of factors of $i$}, \quad \text{with $p[1]=1$.}$$  How do I solve this recursive relation in $O(n^{0.5})$ time? I have to write a program for it, and $n$ can be as large as $10^9$. So, some appropriate precomputation and prestorage is allowed, provided that they comply (memory and time wise) with the range of $n$.


I cannot understand the usage of comma after "chapel" in this sentence:      Its long, damp passages, its narrow cells and ruined chapel, were to be within her daily reach, and she could not entirely subdue the hope of some traditional legends, some awful memorials of an injured and ill-fated nun.   Why is a comma used here, and what is the sentence structure?  The sentence is an excerpt from "Northanger Abbey" by Jane Austen.

In the sentence     What’s funny is Cat’s dry humour.   Wouldn’t it be better to put a comma after “funny”:     What’s funny, is Cat’s dry humour.   This question entails a (at the time of writing) heated discussion in the .


Which sentence is correct? are we meeting before the class or are we meeting before class

I'm used to always hearing or seeing a  before certain nouns.  Yet on certain occasions the article is totally omitted, and it bothers me.  I'm wondering what the justification for omitting the article is, especially when the definite article would seem to be required, or if it is just bad English either on the part of the individual in question or more likely by tradition.  The most frequent place I hear this is at the doctor or dentist's office. In every one I have ever visited, the receptionist or assistant always says things like "Doctor will see you shortly" instead of "The doctor will see you shortly."  The wikipedia article linked above says this: "A definite article indicates that its noun is a particular one (or ones) identifiable to the listener".  In the case of a clinical setting, I know who the doctor is, especially if this is not my first visit.  The people in the office know the doctor even better than I, so it would seem to be inappropriate to omit the article. Even the indefinite article would be incorrect. It further says, under "Zero article":  "In languages having a definite article, the lack of an article specifically indicates that the noun is indefinite."  Since the noun is not indefinite, why are they omitting the article?  Another place I see the article omitted is with the word "bar".  Bartenders apparently don't say "I tend the bar" they say "I tend bar".  Unless a bartender works in multiple bars, it would seem like an article would be required.  Furthermore, "the bar" can mean any bar a person goes to, so even in a case like , it seems like the word "the" should be in the sentence.  The only thing I can think of in this case is maybe the speaker doesn't want to confuse the listener into thinking they work in the legal field.  Is this just a bad habit, a historical corruption or tradition, or is there really a valid reason (or perhaps more than one) for these omissions?


How can I show that $f(z)=\dfrac12\left(z+\dfrac1z\right)$ from $\;\mathbb{C}\setminus\big\{0\big\}\;$ to $\;C\;$ is surjective ? I know the definition, but have never done it with the complex numbers and have some troubles with it. Thanks for help !

The question states:     Let $\Omega$ be the upper half plane minus the unit disk. Show that the map $f: z \mapsto z+1/z$ maps $\Omega$ biholomorphically on the upper plane. Describe the preimages of the lines $\mathrm{Im}(z)=\text{a constant}>0$.   So how exactly does one show the mapping is biholomorphic. I'm not sure where I should start, so unfortunately I haven't made any progress


So my question is completely a theoritical question. For example i have a stick made of the strongest material and lightest material and its lenght is as long as the solar system's diameter. The end of the stick is A and the other end in space is B where a man is sitting. So here on earth i am holding the stick A and move it an angle that the B side covers 1 light year in the same time as the time it required for me to turn the stick to that angle. So does it mean that we can travel faster than light?  Ok so keep aside these things like how will i make that big stick or what will be the effects of the man travelling at that speed blah..blah..blah.. because its just a theoritical question.

Is it possible for information (like 1 and 0s) to be transmitted faster than light?   For instance, take a rigid pole of several AU in length. Now say you have a person on each end, and one of them starts pulling and pushing on his/her end.   The person on the opposite end should receive the pushes and pulls instantaneously as no particle is making the full journey.  Would this actually work?


Tt is true that elements in $A_4$ are squares of elements in $S_4$. Is it true for $A_n$?

I found out that for $n\le 4$ we have $S_n^2=A_n$ with $G^2$ defined by $$G^2:=\{g^2 \mid g\in G\}$$ for any group $G$. Surely we have $S_n^2\subseteq A_n$ for all $n\in\mathbb N$. Is there a characterisation of the squares of the symmetric group? When is $S_n^2$ a group and what does it look like in general?  Edit: So far we found out, that $S_n^2$ generates $A_n$ because each 3-cycle is a square (since we have $g=g^{-2}$) and $A_n$ is generated by the 3-cycles. So we simplified the original question to the question for which $n$ we have $S_n^2=A_n$ and how to characterise the elements which a missing in case we don't have the equality.


With the following line i get a DATE in Y-m-d format.  echo date('Y-m-d',strtotime($result["created_at"]));   Its the creation date of an account. now id like to calculate how old the account is so i can print it out like  5 Years, 5 Months as a example.  any ideas?

How to calculate minute difference between two date-times in PHP?


I have a model and I have unwrapped its faces using simple cubic unwrap. I would like to iterate through the unwrapped faces and select and apply a few operations from external addons to each of them. But I don't quite see in the examples from the documentation how can I make such iteration. How can I achieve this?

I got this UV map, and I want to set the position coordinates for all the four vertices to x=0.5 and y=0.5 (in the center of the green pixel).  I've already tried to use bpy.ops.transform.translate(value=(0,0,0)), but this moves the vertices relative to the current position. Is there a way to set specific coordinates/position for the UV vertices?


How can I center my 2 circle in my column with bs4 please ?

Bla bla bla

Bla bla bla

  Here's the JS Fiddle:  Thanks.

How can I horizontally center a
 within another
 using CSS?

Foo foo


I have 4 different color balls B1, B2, B3 and B4 and their quantity is given by  n1, n2 ,n3 and n4 respectively.  Now, I want to arrange these balls in a straight line next to each other. However, in this arrangement I want no two balls of the same color to be adjacent to each other. ex: if there is 1 ball for each of 4 colors then answer would be 4! = 24    I'm not able to come up with a generic formula for this. Can somebody help me with this?  Update: So I went through that duplicate marked question and the answer mentioned there doesn't has any generic formula which solves my problem!

Given $n_1 $ number of  $1 $'s,  $n_2 $ number of  $2 $'s,  $n_3 $ number of  $3 $'s,  $n_4 $ number of  $4 $'s.  form a sequence using all these numbers such that two adjacent numbers should not be same.  I have tries lot of things but nothing worked.  can somebody tell me how to solve this problem?


I am reversing a string in python though I don't want to reverse the complete string. I am using str[::-1] to reverse the string but excluding the last character.  For example: string = '0123456789' to be reversed to string = '987654321'.  However when the string length is 1 then problem arises with the reversing.  I simply used string=string[len(string)-2::-1]. It works fine for string having length greater than 1. But when string length is 1, python shows some weird results.      w='0123456789'     >>> w[len(w)-2::-1]     =>'876543210'           #PERFECT     >>> w[len(w)-2:0:-1]     =>'87654321'            #PERFECT     >>> w[len(w)-2:-1:-1]     =>''                    #WHAT? - (1)     >>> w[len(w)-2:-2:-1]     =>''                    #WHAT? - (2)     >>> w[len(w)-2:-3:-1]      =>'8'                   #WHAT? - (3)     >>> w[len(w)-2:-4:-1]     =>'87'                  #WHAT? - (4)     #now see what happens when length of w is 1     >>> w='a'     >>> w[len(w)-2::-1]     =>'a'                    #WHAT - (5) as len(w)-2 is -1      >>> w[len(w)-2:0:-1]     =>''                     #PERFECT     >>> w[len(w)-2:-1:-1]     =>''                     #PERFECT as it's [-1:-1:-1]     >>> w[len(w)-2:-2:-1]     =>'a'                    #WHAT - (6)     >>> w[len(w)-2:-3:-1]     =>'a'                    #WHAT - (7)     >>> w[len(w)-2:-4:-1]     =>'a'                    #WHAT - (8)   when w='0123456789' why are the lines marked WHAT - (1) and WHAT - (2) not showing anything while the lines marked WHAT- (3) and WHAT - (4) start from 8 in reverse direction? When w='a' why are the lines marked WHAT - (5) shows 'a' when I am starting from -1 index and what is happening with the lines marked WHAT - (6), WHAT - (7) and WHAT - (8)?

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


The graph of a function z=f(x,y) can always be parametrized as (x,y,f(x,y)). Show that in this case the "old way" (using the derivative and gradient) and the "new way" (Parametrizing the surface and using T vectors) for finding the tangent plane at a point always agree.   I have no idea how to do this problem. I think he wants us to show that two different ways lead to the same tangent plane at a point. one is using the partial derivatives, the second is doing it via T vectors. Can someone run me through the steps? Thanks in advance!

The graph of a function z=f(x,y) can always be parametrized as (x,y,f(x,y)). Show that in this case the "old way" (using the derivative) and the "new way" (Parametrizing the surface) for finding the tangent plane at a point always agree.  I have no idea how to do this problem. I think he wants us to show that two different ways lead to the same tangent plane at a point. one is using the derivative, the second is doing it via surfaces. Can someone run me through the steps? Thanks in advance!


I'm using SQL SERVER 2017 GDR version 14.0.2002.14. I want to upgrade to the latest possible version of SQL Server 2017.   My question is can I download CU-17 and directly run the latest cumulative update which is CU-17 version 14.0.3238.1? OR do I need to reinstall SQL Server 2017 RTM version 14.0.1000.169 first?

Keeping in mind the recent vulnerability attacks patches like Spectre and Meltdown , I would like to patch my SQL Server 2014 SP2 (12.0.5000)  1.Description of the security update for SQL Server 2014 SP2 CU10: January 16, 2018 - SP2 CU10   KB4057117  12.0.5571.0 2.Description of the security update for SQL Server 2014 SP2 GDR: January 16, 2018 - SP2 GDR   KB4057120  12.0.5214.6    Can anyone help me for below questions:   Recently we patched our Windows 2012 R2 Standard servers . Is OS Patching different from SQL Sever patching or these patches are already included during monthly OS patching installed ? Since we have both CU10 and GDR , should I apply both ? Which one should I need to first apply GDR or CU 10 ?


I'm trying to dynamically sum the values of some inputs generated with jQuery based on the number set on other input, but cant make them properly sum,I'll be searching a bit more for another way since .each and .click won't work and .on('click' seems to just add the numbers to the variable but if any number is lowered it'll just add it again, if anyone can come with any creative idea, it would be a lot of help  $( document ).ready(function() { var existimos = 0; $('#sacos').change(function() {     var cantidad = $('#sacos').val();      var inputeador = '
';     function imprimesacos(){         if(cantidad > existimos) {             inputeador += '<input id="yosoy' + existimos + '" name="yosoy' + existimos + '" />';             existimos++;             imprimesacos();         };     };     imprimesacos();     inputeador += '
';     $('#imprimidor').html(inputeador);  });  });

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Often times we encounter people who will fake an interest in what you have to say even if they know everything about what you are about to say. For instance someone who is relating an article they may have come across on the internet and you pretend to have not read it only to elicit their opinion about the said article.  The intentions for why they do this might be positive (just being nice) or negative (to see if one speaks truthfully)

Sometimes (well, often) people pretend not to understand what's going on (or pretend not to understand what the other person means, etc.) when in fact they do perfectly well.   For example, Person A is hoping that his friend Person B would let him crash at his place for a couple of days, but, so as not to appear too intrusive, he wants Person B to invite him instead of asking directly. So, he says to his friend:     Hey, Person B! I've just been kicked out of my house and I have nowhere to go. I really have to figure out where to stay the next couple of days.    Person B understands that Person A is hoping that he would offer him to stay at his place. But he chooses to pretend not to understand, and, instead of saying sorry and explaining why Person A cannot stay at his place, person B says:     There's a nice hotel near here, and it's not very expensive. I can give you the address.   Another example. Person B has secretly stolen the wallet of Person A. Person A has figured out that it was person B and when they meet, he says:     My wallet was stolen the other day.   Person B says:     Really? Oh, that's so unfortunate!    What idioms in English would one use to describe the behavior of Person B in the sample situations? I.e. pretending to be stupid or pretending not to understand something rather obvious, or pretending not to know something that you know; in other words, consciously imitating ignorance, indifference, or innocence.  In Russian, the idiom is to pretend to be a fire hose (прикидываться шлангом) or to pretend to be a boot (прикидываться валенком). The Armenian idiom is to pretend to be a donkey (իրեն էշի տեղ դնել). For me, these phrases are not quite unimaginative and cause a certain amount of amusement. I am hoping to find an English equivalent (or equivalents) that would be informal and/or sound funny(-ish), but that's not essential.  Naturally, I tried to look up the translation in the dictionary before asking, but to no avail, presumably because the phrases mentioned above are rather informal.


The question is simple: why aren't there elementary particles to be found in Nature which have an intrinsic spin of $\frac{3}{2}$? Do the laws of physics (say, quantum field theory) prohibit their existence? Why shouldn't there be an intermediate value (between spin $1$ and $2$, both of which do exist)?

Can the physics complications of introducing spin 3/2 Rarita-Schwinger matter be put in geometric (or other) terms readily accessible to a mathematician?


I am a hobbyist Just starting with java about 5 months ago. I created this project for just fun. Coming here was my last resort, normally I can solve these problems on my own. I keep getting this error occasionally when I move my player.  Exception in thread "Thread-2" java.lang.NullPointerException at java.util.LinkedList.node(Unknown Source) at java.util.LinkedList.get(Unknown Source) at Handler.render(Handler.java:55) at Game.render(Game.java:136) at Game.run(Game.java:76) at java.lang.Thread.run(Unknown Source)    I have plenty of other problems with this project this is only my second game I've attempted to make on my own If you could help With any other errors you see that whould be very helpful.(Have never Used Stack before)

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?


I have read  about how to use the Windows key and the left/right arrow to dock a window against the right or left side of your screen.   My question is how does one perform that command with a keyboard that does not have a Windows key?

I'm using a very old keyboard that doesn't have a physical Windows key — it does have a  and an AT/XT switch on the back — but I don't want to completely miss out on the functionality of the Windows key.  Is there some group of keys in Windows 7 Pro that simulates Win when used together? In other words, I want to be able to take any key combination that uses Win, mentally remove Win and drop in this other group of keys and have the original combo work.  If no such combination exists, how can I create one?  I know that I could just plug in a newer keyboard that has a Windows key, but the whole point of this question is to avoid that. None of the existing  questions seem to address this; the closest is , but it doesn't actually say how to create the mapping.  This is for my work computer, so "install this utility/plugin" isn't a good option for me. Feel free to answer with those for the benefit of others, though.


How do I add space to my /boot directory? Every time I try to  upgrade I am told that I need 20MB more space (for a total of about 80MB), and I have already run commands to free up all unused kernels and headers. I have 60MB free, and am currently using 40MB. I am really stuck. Please help.

Here's my problem. I'd like to reinstall Ubuntu. My laptop is an old HP Compaq nx7400. The optical drive went wrong, it can't read discs. I would use a USB port instead but the laptop won't boot from it. (It won't boot even if I set USB the first in the boot order in BIOS settings. Also on start up after pressing F9 to choose boot device USB won't appear in the list, only optical disk, netbook disk and network if I enable it.)  I wanted to resize the boot partiton to make space for the installation but I couldn't do that because it seems that the whole HDD is the boot partiton so it can't be unmounted using Gparted.  My partition system is the following:  Disk /dev/sda: 250.1 GB, 250059350016 bytes 255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000e6661     Device Boot      Start         End      Blocks   Id  System /dev/sda1   *        2048   486318079   243158016   83  Linux /dev/sda2       486320126   488396799     1038337    5  Extended /dev/sda5       486320128   488396799     1038336   82  Linux swap / Solaris   So how can I make a new partition to be able to install a "new" Ubuntu and get rid of the old one. Or any better solution for this problem? I hope it's not a catch 22...


Consider the following alternative implementations that derived, internal classes are intended to override, returning true:  public virtual bool IsInternal => false;   ...and...  public virtual bool IsInternal() => false;   What is the difference memory- and performance-wise?   Can the compiler detect the static results and, when optimizing/inlining, use them instead of saving the property value for each instance or invoking the function?  Can these virtual members be inlined by the compiler at all and what would the impact be?

As a sort of follow up to the question called , what is the (major) differences or similarity in how the Java Virtual Machine works versus how the .NET Framework Common Language Runtime (CLR) works?  Also, is the .NET framework CLR a "virtual machine" or does it not have the attributes of a virtual machine?


So while making the following program I am getting the errors as mentioned below: I don't know why the IDE is not able to find my images and the images are in the same folder as the .java files. I am using eclipse neon   Exception in thread "main" java.lang.NullPointerException  at javax.swing.ImageIcon.<init>(Unknown Source) at gui_22.gui.<init>(gui.java:24) at gui_22.MAIN.main(MAIN.java:6)   The code is as follows:  Main Class  import javax.swing.JFrame; public class MAIN(){     public static void main(String[] args);       gui go = new gui();       go.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       go.setSize(300,200);       go.setVisible(true);     } }   Gui Class  import java.awt.FlowLayout; import.java.awt.event.ActionListener; import java.awt.event.ActionEvent; import javax.swing.JFrame; import javax.swing.JButton; import javax.swing.Icon; import javax.swing.ImageIcon; import javax.swing.JOptionPane;      public class gui extends JFrame{  private JButton reg;// to create buttons  private JButton custom;// Same as above  public gui(){               super("The Title"); //Allows access to the superclass.               setLayout(new FlowLayout());                reg = new JButton("reg Button");               add(reg);                Icon b = new ImageIcon(getClass().getResource("b.png"));               Icon x = new ImageIcon(getClass().getResource("a.png"));                custom = new JButton("Custom",b);               custom.setRolloverIcon(x);               add(custom);               HandlerClass handler = new HandlerClass();              reg.addActionListener(handler);//adding a handler for the button              custom.addActionListener(handler);    }           private class HandlerClass implements ActionListener{          public void actionPerformed(ActionEvent event){             JOptionPane.showMessageDialog(null,String.format("%s", event.getActionCommand()));          }     }   }


I'm using Ubuntu 16.04.3 LTS. I've been using it for over a year, updating every couple of months with no problems. Today I updated and I got these strange public key errors. I have no idea what this means nor where to start.  Here are the errors:  Err:9 http://dl.google.com/linux/chrome/deb stable Release.gpg                  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E Fetched 308 kB in 1s (159 kB/s)                                                 Reading package lists... Done W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error:      http://dl.google.com/linux/chrome/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E W: Some index files failed to download. They have been ignored, or old ones used instead.   I already tried researching on-line but have found the explanations to be extremely confusing. Please help me understand:  1) What these errors mean.  2) How to fix them.

I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal?


I have two separate in-depth interests in two academic fields.  One of them in pure math (PhD in probability, also interested in complex analysis and differential geometry).  The other one is in software/computer science systems (privacy, distributed systems, this is where my current day-job is). I do not want to spend my life having to give up one of them because I find both very interesting.  But apparently Morera once said that having very in-depth knowledge about a narrow field is better than superficial knowledge in several fields.  Is his advice correct?  Is it possible to make contributions in both areas?  I am currently 34 and in between early-career mid-career stage.  Thanks,

Most research profiles I've seen focus on a set of similar topics. Does anyone have experience in partaking in / conducting research in 2+ disparate fields? (especially if 1 of the fields is pretty different than what they studied in an institution)  For example:   Pure mathematics and biology (e.g. solving an open math problem and studying purring in cats) Aerospace engineering and psychology (e.g. modeling vortices and researching psychological effects of isolation)   If a person had interest in researching a multiple, ranging topics, what advice would you give them? How do you think they should go about doing it? (if you'd recommend they do it at all)  Edit - I'm an undergraduate mechanical engineering student. I'm interested in eventually researching two topics, one in my chosen field, one in genetics.


What are the most important .dll files Windows use?  I'm making a Uplink like hacking game and one of the feature I'm working on would allow you to "destroy" a machine by deleting key Windows files.  The problem is, I'm not quite sure what those files are.  So far all i have is Kernel32.dll. What else could i add?  Thanks.

Where can I find a good resource which can tell me more about any installed DLL on my Windows machine?


ANOVA Test is used on mean score of individual studies' parametric estimates with fixed and Known population or random unknown population.

In simple terms, how would you explain (perhaps with simple examples) the difference between fixed effect, random effect and mixed effect models?


I have a graphic for my company & I need it to be made larger so that the sign company can grow the image without loosing quality. How do I do that? I downloaded Alien Skin Software because I heard that the software would be able to help. I don't have Photoshop so I am looking for something easy. All help would be appreciated.

Is it possible to make a .jpeg photo larger without losing "quality"?  I have a photo that is 450px x 750px and would like to make it 3 times bigger for web not print?  I've been told that Illustrator is the tool to make it happen and I have Illustrator CS6.


The eigenvalue equation of the $L^2$ operator is given by  $$L^2f_l^m = \hbar ^2l(l+1)f_l^m$$  Side: So a determinate state for some observable $Q$ is a state where every measurement of $Q$ returns the same value (let this value be $q$). Then the standard deviation of $Q$ in a determinate state would be zero, i.e.  $$\sigma ^2 = \big\langle (\hat{Q} - \big\langle Q \big\rangle )^2\big \rangle = 0$$  if every measurement gives $q$, then $\big\langle Q \big\rangle$ = $q$. Then using the rules of Hermitian operators, we can get  $$\hat{Q}f = qf$$  So my question is, given the very first equation, why is the magnitude of $L$, in units of $\hbar$, $\sqrt{l(l+1)}$? The eigenvalue of $L^2$ in units of $\hbar$ is $l(l+1)$.   From what I wrote above, $\big \langle L^2 \big \rangle = l(l+1)$.   In general, $\sqrt{\big \langle L^2 \big \rangle} \neq L$. So why is it that, $L = \sqrt{l(l+1)}$?   I'm trying to understand the magnitude of the $\vec{L}$, which in the common illustration shown to demonstrate that $L_z$ can never be greater than $L$, is said to be $\sqrt{l(l+1)}$. But all they did in Griffiths was take the square root of the eigenvalue of the $L^2$ operator.

I simply have no idea how this result is found $$I=\hbar  \sqrt{\ell(\ell+1)}.$$ The result seems to just be dumped in textbooks rather than explained. I can get the result that $I_z=\hbar m_j$. Please explain as clearly as possible how this is derived.  Also, any pointers towards any books/videos that may help me learn quantum mechanics would be appreciated.


I am trying to design a company logo via Tikz and thought an editor would be a huge plus to the task. Are there any good drag and drop (with minimal coding) Tikz editor? Platform is Mac OS X. I am using Sketch but would love to use Tikz.

Are there any   editors for ? Perhaps something similar to    but for PGF/TikZ?   If there is no WYSIWYG editor for this tandem, is there one perhaps that allows the user to easily generate PGF/TikZ templates?  Alternatively, how can I most easily generate PFG/TikZ code from a visual conception? Do people mostly code their PGF/TikZ graphics from scratch?


I am flying from London to Maun botswana and changing in johannesburg. I have bought two seperate tickets and have a 2 hour stop over.   I am only taking hand luggage but will i need to exit customs and re-check in for my next flight? Or can I walk straight through to international flights? Is there somewhere to check in?

Travelling from London, Heathrow to Lusaka, via Jo'burg, how much time should we allow for the international connection in Jo'burg?  Is it a matter of arriving at one gate and leaving at another, or do you have to go through passport control, customs, security?


I wrote out a proof using the definition of the derivative for the function $f(x) = \sin(\theta)$ to show that $f'(x) = \cos(\theta)$, in order to use L'H's rule to show that the limit, $x \to 0$, of $\frac{\sin(x)}{x}$ equals 1, but as one professor in my department warned me: this uses circular reasoning.   There is a factor of $\frac{\sin(h)}{h}$ when using the definition   $$ f'(x) = \lim_{h \to 0} \frac{\sin(x+h) - \sin(x)}{h},$$  and we must show that   $$\lim_{h \to 0} \frac{\sin(h)}{h} =1,$$  to continue the proof.  So, how can we still justify using L'H's rule for $\lim_{x \to 0} \frac{\sin(x)}{x}$?    We're using the result to prove the result, which is absurd.  Thanks,

How do I prove that the derivative of $\sin$ is $\cos$ ?  This part is easy:  $$ \begin{align*} \sin'(x) &= \lim_{\Delta x \to 0} \frac{\sin(x + \Delta x) - \sin(x)}{\Delta x}  \\ \sin'(x) &= \lim_{\Delta x \to 0} \frac{\cos(x)\sin(\Delta x) + \sin(x) \cos(\Delta x) - \sin(x)}{\Delta x}  \\ \sin'(x) &= \lim_{\Delta x \to 0} \left(\cos(x)\frac{\sin(\Delta x)}{\Delta x} + \sin(x)\frac{\cos(\Delta x) - 1}{\Delta x}\right)  \\ \end{align*} $$  but where do I go from here?


I came across this sentence:  "His memory was like that of a baby."   I was wondering why the possessive "baby's" wasn't used and why "baby" is acceptable whereas the possessive form is required in this sentence:   "Ian's car was like that of his."

As  shows, we nearly always use the possessive form of personal pronouns for friend of mine/his/ours/etc.  But when it comes to actual names, we prefer  without the possessive apostrophe. That preference is even more marked with, say, . Not that I think the usage itself is particularly American - it's much the same with .  Personally, I find friend of him grates. In general I've no strong feelings either way as to whether it's friend of Peter or friend of Peter's (though I deplore the possessive in ), but in line with many others, I really don't like the possessive in relation to things like countries.  Why is this?   Edit: Noting an apparent "progression" (pronoun -> person -> nation) marked by reduction in use of the possessive, I checked at a finer "granularity". NGram shows that although it does occur,  virtually "flatlines" against friend of mine. But the bias reduces through of you, of us, and by the time I get to  it's much less extreme. There seems to be something "egocentric" about the double possessive.  Presumably when babies learn to speak, they soon notice that possessive pronouns, possessive apostrophes, and the word "of", all do the same job. Parents would correct a child who says "of mine's", but probably wouldn't even notice the same "redundancy" in "of Peter's". Younger speakers are unlikely to even be talking about something "of America's". Perhaps as we mature we tend to discard the "double possessive" for the more "distant" things that only adults are likely talk about, but we keep it for "closer" people because that's how we spoke when we were younger.  EDIT2 I note that I'm a great fan of him is vanishingly rare compared to ...fan of his, but with ...fan (of John) the double possessive occurs far less often than ...friend (of John's). Usage seems to be affected by the noun before "of" as well as the one after it. This is getting complicated...


I found UI overlapping issue here   And Top-Right side all three buttons are not working on click after scrolling down due to z-index or overlapping issue.

I was having a look at an old question of mine when I browsed the  from the timeline. I scrolled downwards and realized the Review completed panel comes along for the ride. While that might be , tags flowing over top of it as pictured below probably isn't.  Here's a .gif of the Question and Duplicate tabs flowing over it as well. Note that the timeline button also flows over. If vote buttons are present, they will also flow over it.  Reproduced on Chrome and Microsoft Edge. Update Per  by Tiago Martins Peres, this issue also happens in other Review types, namely Late Answers, First Posts and Low Quality Posts. In addition to that, it is causing the action buttons on reviews to become unclickable if you scroll low enough.  As a temporary workaround, you can use 's , which  this issue.


I have a class called "Complex" which is intended to represent complex numbers. I have defined an empty default constructor for the class that only prints a message to the screen. When I try to create an object of the class in the main function as follows:  Complex c1();   The compiler(I am using BorlandC) doesn't give a syntax error but it doesn't create the object. How does the compiler interpret this line?

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


When Performing a linear regression in r I came across the following terms.    NBA_test =read.csv("NBA_test.csv")  PointsPredictions  = predict(PointsReg4, newdata =  NBA_test)  SSE = sum((PointsPredictions - NBA_test$PTS)^2)      SST = sum((mean(NBA$PTS) - NBA_test$PTS) ^ 2)  R2 = 1- SSE/SST   In this case I am predicting the number of points. I understood what is meant by SSE(sum of squared errors), but what actually is SST and R square? Also what is the difference between R2 and RMSE?

For regression problem, I have seen people use "coefficient of determination" (a.k.a R squared)  to perform model selection, e.g., finding the appropriate penalty coefficient for regularization.   However, it is also common to use "mean squared error" or "root mean squared error" as a measure of regression accuracy.  So what is the main difference between these two? Could they be used interchangeably for "regularization" and "regression" tasks?  And what are the main usage of each in practice, such as in machine learning, data mining tasks?


I'm stumped on this question- A researcher runs an experiment in which levels of factor A are randomly assigned to study the effects of A. Then a second experiment is run in which levels of factor B are randomly assigned. Why is running a factorial design with both factors A and B advantageous over the approach of running two single experiments? Provide at least one single reason.

In The Seven Pillars of Statistical Wisdom book by  Stephen M. Stigler:     William Stanley Jevons, writing in his Principles of Science in 1874:      One of the most requisite precautions in experimentation is to vary   only one circumstance at a time, and to maintain all other   circumstances rigidly unchanged.      Ronald A. Fisher, writing in 1926:      No aphorism is more frequently repeated in connection with field   trials, than that we must ask Nature few questions, or, ideally, one   question, at a time. The writer [Fisher] is convinced that this view   is wholly mistaken. Nature, he suggests, will best respond to a   logical and carefully thought out questionnaire; indeed, if we ask her   a single question, she will often refuse to answer until some other   topic has been discussed.   I continued to finish the book and yet can't understand, what was the insight Fisher got. When googling for an answer it seems the former idea (keep everything fixed and change one thing aka ) is the recommended approach.  What is the insight Fisher is talking about?


Biblatex not showing with biber + apa style...help me, please.  \documentclass[a4paper,12pt]{report} \usepackage[utf8]{vietnam} \usepackage{filecontents} \begin{filecontents*}{mybib.bib} @BOOK{RonCal11th,   author =       {{Ron Larson}{, Bruce Edwards}},   title =        {Calculus},   publisher =    {Cengage Learning},   year =         {2018},   edition =      {11th},   keywords =     {english}, }  @BOOK{NBK2015,   author =       {Nguyễn Bá Kim},   title =        {Phương pháp dạy học môn Toán},   publisher =    {Nhà xuất bản Đại học Sư Phạm},   year =         {2015},   keywords =     {vietnam}, } \end{filecontents*} \usepackage[backend=biber,style=apa,]{biblatex} \addbibresource{mybib.bib} \begin{document} \printbibliography[heading=subbibliography,keyword={vietnam},title={Tiếng Việt}] \printbibliography[heading=subbibliography,keyword={english},title={Tiếng Anh}] \end{document}

Running the minimal example  \documentclass{article} \usepackage{filecontents} \begin{filecontents*}{\jobname.bib} @ARTICLE{example,   author  = {Other, Anthony Norman},   title   = {Some things I did},   year    = {2014},   journal = {J.~Irrep. Res.},   volume  = {1},   number  = {1},   pages   = {1-10} } \end{filecontents*} \usepackage[backend=biber]{biblatex} \addbibresource{\jobname.bib} \begin{document} Hello\cite{example}. \printbibliography \end{document}   I get the warning There were undefined references.  I have read  and know that I need to run:   LaTeX Biber LaTeX   However, my editor is only set up to run BibTeX. How do I go about setting up my editor/IDE to be able to run Biber, and how do I run the LaTeX/Biber/LaTeX cycle?  Answers (sorted alphabetically by editor name)                    Answer guidelines   Each answer should be for one editor. If the editor is cross-platform, if possible give a single answer with notes covering the minor platform variations. Please edit the question to include new answers in the 'link list' Each answer should be 'stand alone', i.e. don't say 'It's almost the same as editor Y but ...' for the editor part Instructions for 'build tools' such as arara or latexmk are welcome but should explain how to set up the editor in question as not all editors allow simple addition of arbitrary tools


I looked it up. It means "while" and is used mostly in Britain. Could anyone explain to me how to use it?

When should whilst be used instead of while?  For example, should I use the first or the second sentence?      They don't do this whilst they do that.   They don't do this while they do that.   Which would be correct?


Take these two simple statements:  SELECT '1 IS NOT IN THE LIST' WHERE 1 NOT IN (2, 3, 4) SELECT '1 IS NOT IN THE LIST' WHERE 1 NOT IN (NULL, 2, 3, 4)   The results you will get are:    Basically, as soon as you add NULL to the list, the NOT IN condition always returns FALSE, implying that (in this case) 1 = NULL  Can someone explain why this happens?  Following on from that, why does this statement (the opposite of the NOT IN that returned FALSE) not return TRUE?  SELECT '1 IS IN THE LIST' WHERE 1 IN (NULL, 2, 3, 4)

This issue came up when I got different records counts for what I thought were identical queries one using a not in where constraint and the other a left join. The table in the not in constraint had one null value (bad data) which caused that query to return a count of 0 records. I sort of understand why but I could use some help fully grasping the concept.  To state it simply, why does query A return a result but B doesn't?  A: select 'true' where 3 in (1, 2, 3, null) B: select 'true' where 3 not in (1, 2, null)   This was on SQL Server 2005. I also found that calling set ansi_nulls off causes B to return a result.


I use Ubuntu 12.04. I am trying to add the user gefalko to the www-data group. I use   root@xxx~# usermod -a -G www-data gefalko   If I understand correctly, I should now see www-data in the output of groups when run by gefalko:  gefalko@xxx:~$ groups   However, there is no www-data in the output:  gefalko adm cdrom sudo dip plugdev lpadmin sambashare   I want to edit index.php owned by www-data, but I can't (permission denied):  gefalko@xxx:/var/www/html/projectx$ ls -l total 1320 ... -rwxrwxr-x  1 www-data www-data    1613 Bal 18 10:18 index.php ...

I changed permissions of a file (chmod g+w testfile) and running ls -l testfile gives:  -rwxrwxr-x 1 user1 user1 0 2011-01-24 20:36 testfile   I then added a user to that group ("/etc/group" has user1:x:1000:user2 line), but am failing to edit that file as user2. Why is this so?


I don't know what this warning means   Overfull \hbox (95.6542pt two wide) in paragraph at lines 94--95   I added   \showboxdepth=\maxdimen \showboxbreadth=\maxdimen   from other repost, but the warning still going

I often see output from TeX with the warning overfull hbox, badness 10000. What does this message mean?


Can a force, which has magnitude of an irrational number or does not end (ex : 1/3), act upon any particle?  If photon of particular wavelength lambda has some energy say E, then can the photon/group of photons exert a force which is irrational in its magnitude. If yes, then how?   If the desired force is pi(3.1415...), how can this force be attained by sum of force in a finite amount of time.  pi = 3 + 0.1 + 0.04 + 0.001 + 0.0005 + 0.00009 + ....... The above sequence does not end; And if a photon can exert a finite amount at a time, we would either require infinite amount of time or infinite amount of photons to create an infinitesimally small force.   My teacher says that the forces which are of magnitude of any irrational number are exerted on bodies. And it is just the incapability of humans that we cannot image that particular magnitude.

Suppose I have a  that is infinitely precise. Also suppose that this caliper returns not a number, but rather whether the precise length is rational or irrational.  If I were to use this caliper to measure any small object, would the caliper ever return an irrational number, or would the true dimensions of physical objects be constrained to rational numbers?


I mean how can we say that in 5730 years, 1/2 the no. of C14 nucleus will decay because in reality we don't know when a particular nucleus will decay

Carbon-14 has a half-life of 5,730 years.  That means that after 5,730 years, half of that sample decays.  After another 5,730 years, a quarter of the original sample decays (and the cycle goes on and on, and one could use virtually any radioactive isotope).  Why is this so?  Logically, shouldn't it take 2,865 years for the quarter to decay, rather than 5,730?


When I try to login to the Android Stack Exchange app with my Google account I get . I tried it on multiple networks and on cellular but it gives me the same error consistently.  I also tried multiple phones running Oreo and Pie, tried reinstalling a few times on each and it always gives me the same error. I don't have a rooted device and no ad-blocker is running. When I try to log in with Chrome on the same phone it works normally and no error occurs.  How can I log into my account on Android?

I tried logging in with a Google account, but I got the following error:


I am interested in understanding why $x^4 - 17 = 2 y^2$ has no rational solutions.  My first approach was to show that every rational solution leads to an integral solution but that doesn't seem to be the case.

There is a hint to show that if there were points in $\mathbb{Q}$, then there would exist $r,s, t \in \mathbb{Z}$ with $\gcd(r, t) = 1$ such that $2s^2 = t^4 - 17r^4$ , and then show that any prime dividing $s$ is a quadratic residue modulo $17$.  I'm stuck on the first bit - if you suppose $\left(\frac{a}{b}, \frac{c}{d}\right)$ is a point on the curve in $\mathbb{Q}$ (so $a, b, c, d \in \mathbb{Z}$) then you get to $2a^2d^4 = b^2c^4 - 17b^2d^4$, but I'm not sure where to go from here since you don't know that $b$ is a square?


I'm new to the Horde and I'm a death knight but I'm not quite sure how to get back to the horde main city, I'm in silvermoon city and I just don't know how to get there as dumb as it sounds, could someone help me?

I have a level 11 Blood Elf and want to spend some of my honor points. I've heard that I could spend them in Orgrimmar, but the only problem is getting there.  How do I get to Orgrimmar from Silvermoon City? I'm not in a level 25 guild, so nobody can teleport me there. :(


$f:\mathbb{R}\to\mathbb{R}$ is continuous and $\int_{0}^{\infty} f(x)dx$ exists  could any one tell me which of the following statements are correct?  $1. \text{if } \lim_{x\to\infty} f(x) \text{ exists, then it is 0}$  $2.  \lim_{x\to\infty} f(x) \text{ must exists, and it is 0}$  $3. \text{ in case if f is non negative } \lim_{x\to\infty} f(x) \text{ exists, and it is 0}$  $4. \text{ in case if f is differentiable } \lim_{x\to\infty} f'(x) \text{ exists, and it is 0}$  I solved one problem in past which says: if $f$ is uniformly continuos and $\int_{0}^{\infty} f(x)dx$ exists then $\lim_{x\to\infty} f(x)=0$, so the condition in one says $f$ is uniformly continuous? and hence $1$ is true? well I have no idea about the other statements. will be pleased for your help.

I was thinking about the following problem:  Let $f:\mathbb R\rightarrow \mathbb R$ be a continuous function such that $\int_{0}^{\infty}f(x)dx$ exists. Then which of the following statements are correct? (a) If $\lim_{x\to\infty}f(x)$ exists, then $\lim_{x\to\infty}f(x)=0,$ (b) The limit $\lim_{x\to\infty}f(x)$  must exist and is zero, (c) In case $f$ is a nonnegative function, the limit $\lim_{x\to\infty}f(x)$ must exist and is zero, (d) In case $f$ is a differentiable function, the limit $\lim_{x\to\infty}f'(x)$  must exist and is zero.  If I take  $f(x)=e^{-x}$, so that the given condition is satisfied then we see that options (a) and (c) are correct. But I am not sure about the choice given in (b) and (d). But If I have to prove it in general, then how can I prove it? I mean an alternative better approach. Please help. Thanks in advance for your time.


I have searched a lot difference between singleton and static class, Only I could convince myself is syntactical difference,on which I am not interested.  Could anyone tell me the real difference between static and singleton ? When I should use only singleton not static or any other ?

What real (i.e. practical) difference exists between a static class and a singleton pattern?  Both can be invoked without instantiation, both provide only one "Instance" and neither of them is thread-safe. Is there any other difference?


I am reading over the MSDN's tutorial on lock here .  It says lock(this) is not a best practice if the instance is of public type. However I don't see why the instance being a public type would be a problem assuming lock owns the object atomically. Can anyone please shed a light? If that is not the case, I don't see though how a private object would help protect the critical section either?

The  says that public class SomeObject {   public void SomeOperation()   {     lock(this)     {       //Access instance variables     }   } }  is "a problem if the instance can be accessed publicly". I'm wondering why? Is it because the lock will be held longer than necessary? Or is there some more insidious reason?


This image of the crack in my passport's cover page. It was pointed out as damaged by VFS global at New Delhi.Will it cause rejection? I have applied for Estonia visa for conference.

My Indian passport threading is coming off i.e. the cover of the passport is coming off, there are only 2 threads remaining.   Will it be a problem at the airport when going abroad ? Also anyone who has experience of getting a replacement passport fairly quick ? Because I need to get a passport in like 15 days.


I've installed macOS Sierra and I got an annoying behavior, which I'm trying to solve:  Prior to Sierra (and in Windows, too): I have two languages - English and Hebrew. I'm switching between them using cmd+space. When in English, I'm using the caps lock to write uppercase letters. That's the exactly same behavior as any other English keyboard user. However, when using Hebrew as the input source, I'm using caps lock to write in english (small letters only). In this way, I can use some english terms in my hebrew sentences (which is quietly common, to be honest). This is the behavior in Windows too.  Since Sierra: Apple disabled this function, so when I'm using Englis I can use caps lock to move between uppercase and lowercase as excepted. However, when in Hebrew - the caps lock does not work (the green light automatically turns off).  I'll note that when Googling this issue, I saw that Apple added the ability to switch languages using the caps lock. That solution does allows me to switch between Hebrew and English, but it rises another problem - In English, I can't switch between uppercase and lowercase letters (since the caps lock already mapped to switch between input sources). The only way to get into uppercase letters, is to hold the caps lock for 3 seconds, and that makes it very hard to type.  Anyone knows how to restore the functionality of the caps lock to the old, good, way?

Downloaded and installed macOS Sierra (10.12) on 10/1/16.  Since then, my Caps Lock key is behaving weirdly different (I'm an OS X user since Mavericks).  Note: This only seems to affect users with more than one language as their input source.  Explanation: Caps Lock simply does not work when a (update: Non-Latin language) language other than English (in my case, Hebrew, an RTL language) is set as the input language. When that's the case and Caps Lock is pressed, it simply blinks for a second and then turns off again, but then and turns off. Even when I am able to turn it on, it doesn't have the same effect (all keys behave as if Caps Lock is off)  Why is this bad: Just a small example — take a look at the bottom-right key, which is ? (or / when Caps Lock is on). When Hebrew is selected, it's actually a period (.) and that is normal. Prior to Sierra, I could press the Shift key to get a ? and hold Caps Lock to get /. Right now I can't use  / when I'm typing in a language other than English because Caps Lock doesn't work.   Note that Caps Lock works just as expected when English is set as the input source.


Because I hadn't sufficient memory,but the files remains on mine phone but i can't find them and delete theM. On google play it says that the game isn't installed and in the phone either.How to free my phone? And other question how to use the space on sd card..? I have samsung galaxy s4 with 4.4.2 android NO ROOT

I recently tried installing an app that was around 1.8GB to my Nexus 7 (8GB). it's a device with unfortunately small internal storage, so I had about 2GB free before attempting the install. I come back later, the download has failed due to not enough storage space. no big surprise there. but now, my device only has 350MB free! strangely enough, the graph in storage settings appears as if it had that full 2GB or so free, but lists only 350MB.  how can I get my free storage space back from the failed download? my device is rooted, no root file browser or terminal, but I do have the Android SDK and tools.  another thing to note: my device is constantly complaining about its free space in the form of a notification. also, every app download from Google Play (even a tiny 2MB app) fails due to not enough storage space. for some reason, that always happens when my device goes under 500MB free. I don't understand it, but, it's 'normal'.


I'm not so experienced in bash scripting, so consider studying it on practice. Recently i was trying to make simple script which should reveal all files at least 1 GB sized and faced with problem escaping white-spaces in names.  It's working fine in terminal if i do:  $ find /home/dem -size +1000M -print|sed -e 's/ /\\ /' /home/dem/WEB/CMS/WP/Themes/Premium_elegant_themes/ETPSD.rar /home/dem/VirtualBox\ VMs/Lubuntu13.04x86/Lubuntu13.04x86.vdi /home/dem/VirtualBox\ VMs/Win7/Win7-test.vdi /home/dem/VirtualBox\ VMs/FreeBSD9.1/FreeBSD9.1.vdi /home/dem/VirtualBox\ VMs/backup_Lubuntu13.04x86/Lubuntu13.04x86.vdi /home/dem/VirtualBox\ VMs/Beini-1.2.3/Beini-1.2.3.vdi /home/dem/VirtualBox\ VMs/BackTrack5RC3/BackTrack5RC3.vdi /home/dem/VirtualBox\ VMs/WinXPx32/WinXPx32.vdi   But in this script:  #!/bin/bash  for i in "$( find /home/dem -size +1000M -print|sed -e 's/ /\\ /' )"  do    res="$( ls -lh $i )"   echo $res done    It gives error, and as you may see left part stripped:  ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/Lubuntu13.04x86/Lubuntu13.04x86.vdi: No such file or directory ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/Win7/Win7-test.vdi: No such file or directory ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/FreeBSD9.1/FreeBSD9.1.vdi: No such file or directory ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/backup_Lubuntu13.04x86/Lubuntu13.04x86.vdi: No such file or directory ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/Beini-1.2.3/Beini-1.2.3.vdi: No such file or directory ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/BackTrack5RC3/BackTrack5RC3.vdi: No such file or directory ls: cannot access /home/dem/VirtualBox\: No such file or directory ls: cannot access VMs/WinXPx32/WinXPx32.vdi: No such file or directory -rw-rw-r-- 1 dem dem 3.1G Jul 13 02:54 /home/dem/Downloads/BT5R3-GNOME-32/BT5R3-GNOME-32.iso -rw------- 1 dem dem 1.1G Dec 27 2012 /home/dem/WEB/CMS/WP/Themes/Premium_elegant_themes/ETPSD.rar   I need script to show files with white-spaces + retrieving actual size of each file which ls -lh do. Without sed formatting:  $ find /home/dem -size +1000M -print /home/dem/WEB/CMS/WP/Themes/Premium_elegant_themes/ETPSD.rar /home/dem/VirtualBox VMs/Lubuntu13.04x86/Lubuntu13.04x86.vdi /home/dem/VirtualBox VMs/Win7/Win7-test.vdi /home/dem/VirtualBox VMs/FreeBSD9.1/FreeBSD9.1.vdi /home/dem/VirtualBox VMs/backup_Lubuntu13.04x86/Lubuntu13.04x86.vdi /home/dem/VirtualBox VMs/Beini-1.2.3/Beini-1.2.3.vdi /home/dem/VirtualBox VMs/BackTrack5RC3/BackTrack5RC3.vdi /home/dem/VirtualBox VMs/WinXPx32/WinXPx32.vdi

I have a bash shell script that loops through all child directories (but not files) of a certain directory.  The problem is that some of the directory names contain spaces.    Here are the contents of my test directory:  $ls -F test Baltimore/  Cherry Hill/  Edison/  New York City/  Philadelphia/  cities.txt   And the code that loops through the directories:  for f in `find test/* -type d`; do   echo $f done   Here's the output:   test/Baltimore test/Cherry Hill test/Edison  test/New York City test/Philadelphia   Cherry Hill and New York City are treated as 2 or 3 separate entries.  I tried quoting the filenames, like so:  for f in `find test/* -type d | sed -e 's/^/\"/' | sed -e 's/$/\"/'`; do   echo $f done   but to no avail.  There's got to be a simple way to do this.    The answers below are great.  But to make this more complicated - I don't always want to use the directories listed in my test directory.  Sometimes I want to pass in the directory names as command-line parameters instead.  I took Charles' suggestion of setting the IFS and came up with the following:  dirlist="${@}" (   [[ -z "$dirlist" ]] && dirlist=`find test -mindepth 1 -type d` && IFS=$'\n'   for d in $dirlist; do     echo $d   done )   and this works just fine unless there are spaces in the command line arguments (even if those arguments are quoted).  For example, calling the script like this: test.sh "Cherry Hill" "New York City" produces the following output:   Cherry Hill New York City


I have a large frozen haggis that I'd like to use for dinner Saturday night.  when do i start to thaw it, and whats the safest method of thawing to prevent both food borne illness and to preserve quality of the product?  I already read the question about cooking haggis from frozen, and decided I don't want to do that.

Since reading the answers to my question about  I've been good about giving my meat time to defrost in the refrigerator. However, my plans for tonight have changed and I'd like to defrost some ground beef that is completely frozen for dinner this evening. What are my options to do so quickly and safely?


A very basic question, sorry! I have a Giant hybrid bike, that currently has 700x38 tyres on 622x29 rims. I need to replace the tyres, as they are getting old and was wondering if I could change the tyres to 700x32, do you think that it is a good idea, if not any other suggestions? I was thinking of Gatorskin's for commuting, but am a bit worried about how they will handle in the wet. Thanks for your help

We often get questions on bicycles.stackexchange about fitting wider or narrower tires to bicycles. We have a large number of these with answers suiting the specific bike or style of bicycle in question, but I have been unable to find one that provides a generic answer covering off all things that need to be considered. For most bicycles, the answer is the same regardless of the specific style and sizes of tires in question.   This is intended as a canonical question that we can point closed questions to.


A post "" used two ways to model the polynomial regression: (a) poly(..., ...); (b) I(...). Below is the example:  set.seed(20) q <- seq(from=0, to=20, by=0.1) y <- 500 + 0.4 * (q-10)^3 noise <- rnorm(length(q), mean=10, sd=80) noisy.y <- y + noise  # fitting polynomials #     two methods model_a <- lm(noisy.y ~ poly(q,3)) model_b <- lm(noisy.y ~ q + I(q^2) + I(q^3)) # their summary are all the same except the coefficients summary(model_a) summary(model_b)   The post said that:      q, I(q^2) and I(q^3) will be correlated and correlated variables can   cause problems. The use of poly() lets you avoid this by producing   orthogonal polynomials, therefore I’m going to use the first option (i.e., poly()).   I am confused that:  (1) Why does the q, I(q^2) and I(q^3) cause problems?  (2) According to summary(), these two models are all the same, except the Coefficients . Why the coefficients are different, while others are the same? Shouldn't they all different, or all the same?

When adding a numeric predictor with categorical predictors and their interactions, it is usually considered necessary to center the variables at 0 beforehand. The reasoning is that the main effects are otherwise hard to interpret as they are evaluated with the numeric predictor at 0.  My question now is how to center if one not only includes the original numeric variable (as a linear term) but also the quadratic term of this variable? Here, two different approaches are necessary:   Centering both variables at their individual mean. This has the unfortunate downside that the 0 now is at a different position for both variables considering the original variable. Centering both variables at the mean of the original variable (i.e., subtracting the mean from the original variable for the linear term and subtracting the square of the mean of the original variable from the quadratic term). With this approach the 0 would represent the same value of the original variable, but the quadratic variable would not be centered at 0 (i.e., the mean of the variable wouldn't be 0).   I think that approach 2 seems reasonable given the reason for centering after all.  However, I cannot find anything about it (also not in the related questions:  and ).  Or is it generally a bad idea to include linear and quadratic terms and their interactions with other variables in a model?


I am learning C# programming and building a simple ClickOnce application. I know this question has been asked before, I tried to take guidance from there but as nobody has given the full code (with all using statements etc.) I am getting some errors. So the posts I have come across, I could not comment on any of those to request the full since I need minimum of 50 reputations which I don't have being a beginner.  So here is my code for my simple program:  using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using Microsoft.Win32; // for registry  namespace MyRegApp {   class Program   {     static void Main(string[] args)     {         Console.WriteLine("Hello World!");          // add to start up registry         // The path to the key where Windows looks for startup applications         RegistryKey add = Registry.LocalMachine.OpenSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run", true);         add.SetValue("MyApp", "\"" + Application.ExecutablePath.ToString() + "\"");          Console.WriteLine("Progam installed successfully, please press any key to exit");         Console.ReadKey();     }   } }   But in Visual Studio 2017, Application in Application.ExecutablePath gets a red underline and I get the error that "the name Application does not exist in the current context", or something (screenshot attached).    Could you please advise if I need to put the registry bit in another method, or in another file, or how can I make it to work.  ======= Edit =========  Having fixed the compile issue, I have now run into another problem. I am getting permission errors when I attempt to write to the registry. I have consulted some other posts but have not found anything similar. Below is my current version of code with a snippet for granting myself all necessary permissions, any help will be much appreciated.  namespace MyRegApp { class Program {     static void Main(string[] args)     {         // The code provided will print ‘Hello World’ to the console.         Console.WriteLine("Hello World!");          // add to start up registry         RegistryKey key = Registry.LocalMachine.OpenSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run", true);         RegistrySecurity rs = new RegistrySecurity();         rs = key.GetAccessControl();         string currentUserStr = Environment.UserDomainName + "\\" + Environment.UserName;         rs.AddAccessRule(new RegistryAccessRule(currentUserStr, RegistryRights.WriteKey | RegistryRights.ReadKey | RegistryRights.Delete | RegistryRights.FullControl, AccessControlType.Allow));          try         {             key.SetValue("MyRegApp", "\"" + Assembly.GetExecutingAssembly().CodeBase.ToString() + "\"");         }         catch (SecurityException e) {             Console.WriteLine("Security Exception:\n\n{0}", e.Message);               }          Console.WriteLine("Progam installed successfully, please press any key to exit");         Console.ReadKey();     }  } }

How can I make a Click-once deployed app run a startup?  The best option I found by searching was to set the Publisher on the app to Startup, so the Start menu shortcut would be placed in the Startup folder, but that seems like a huge hack and I would like there to be a Start menu icon people can find.  What options do I have?


I am trying to create a copy of a std::string to a char*. This is my function and its seen result:  void main() { std::string test1; std::cout << "Enter Data1" << std::endl; std::cin >> test1; char* test2; test2 = (char*)test1.c_str(); std::cout << "test1: "<< &test1 << std::endl; std::cout << "test2: "<< &test2 << std::endl; }  Enter Data1 Check test1: 0x7fff81d26900 test2: 0x7fff81d26908   I am unsure if a copy has been created or both of them are pointing to the same location. How to confirm this?

How can I convert an std::string to a char* or a const char*?


can you tell me how can I put questions and get more answers ! what I should do to get more interaction with my posts ! waiting for hours and days maybe months to get an answer or comment is not good ... Really I  want some advices , thanks in advance


Hey I am trying to read Hebrew chars from PhpMyAdmin table and it just comes out as a mess, on the table it look's fine and written in Hebrew but when I move it to php using SELECT the output is like this:   05deu05d9u05e8u05d4u05deu05d9u05e8u05d4u05deu05d9u05e8u05d4   I tried encoding the php page to utf-8 and it didn't helped my table is enconde as  utf8_general_ci  I don't know what to do..  my php code is:  $sql = "select * from sample;";   $conn = mysqli_connect($host,$username,$password,$db);    if (!$conn->set_charset("utf8")) {       printf("Error loading character set utf8: %s\n", $conn->error);   } else {       printf("Current character set: %s\n", $conn->character_set_name());   }   $result = mysqli_query($conn,$sql);  $response = array();  while($row = mysqli_fetch_array($result)) {     array_push($response,array($row[0],$row[1],$row[2],$row[3],$row[4],$row[5],$row[6])); } $str = json_encode(array($response)); $str = clean($str); echo $str; mysqli_close($conn);  function clean($string) {     $string = str_replace(' ', ' ', $string);     $string = preg_replace('/[^a-zA-Z0-9,: -]/', '', $string);     return preg_replace('/-+/', '-', $string); } ?>

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


I had watched the silicon valley season 1 but i did not understood the climax. I don't know what is Weissman score, is it good to be more or less. I had went through the technical same question asked but still i am confused. I want to know in detail.

I accidentally came across Silicon Valley (2014) TV series and I liked it a lot, but I am unable to understand the climax of season one of this series. I am not a hardcore programmer but I know some basics of programming.   During the TechCrunch event what kind of modifications the protagonist made to his compressing software Pied Piper which helped his team to win the event?   Why the protagonist initially become gloomy while compressing a 3D data file which size was greater than 100 GB (from judges) to mere 20 GB?  Why he became happy when the software showed no error?


I have an R9 380, which is supported by the driver. I followed all of AMD's instructions perfectly and everything seemed fine until I restarted. After restarting there was no video but there was sound. The only solution to this problem seems to be uninstalling the driver :/. Is there anyway to get the driver working? Any help would be great, thanks.

I have been having some screen freezing issues on my new Ubuntu 16.04 system, and have been in the troubleshooting process for this issue. I thought it was a graphics driver problem, as I am running an AMD R9 380x card which was supposed to be fully supported by the open-source AMDGPU driver preinstalled with 16.04, but after looking around online, many people seem to have issues with. I thought the answer would be to install the recently released AMDGPU-Pro driver , following the instructions from . However, when I reboot I am getting a black screen. Is there an easy way to revert my changes back? My machine was semi-functional with the freezing issue but now with no video at all is useless to me. How to proceed?


I am using Mean Absolute Value(MAE) and Mean Squared Error(MSE) as my evaluation parameters for the regression model. I am trying to predict the future values for time series model and have used CNN fro the same. However, my CNN model is giving very low values for MSE compared to MAE. On such example is  MAE:0.04978915070122473, MSE:0.004155844765967494   I know for sure that MAE has to be always less than MSE since we are squaring the coefficients in MSE.

Generally speaking, can RMSE be smaller than MAE?  I am calculating RMSE and MAE for my results. In two out of five methods, the RMSE is smaller than MAE. Note that I am using the same data, the same script, and the same code to calculate RMSE and MAE. The only difference is the algorithm to create the models.  I have been over my script several times and everything is ok with the code.  Thank you.


I have a question about the Schengen Area View for Canadians.  On August 30th 2017 I entered the Schengen Area ao on this date my 180 days started. From August 30th to September 12th I was in France. Went back to Canada. On January 26th, I entered again the Schengen Area (Spain). And now here I am. Still in Spain and my 180 days finish today (February 25th).  My question is: Do I have to get out of the Schengen Area to start again my 90 days or it is automatically starting again my 90-180 days so technically I would have now right now here today 90 more days to stay in Spain? Complicated, but very stressed and looking for an answer... Thank you!!!

I have searched the web a lot and could not find an answer that fits my situation. Here are two links that are quite contradictory:       My situation:  I've visited Portugal in December 2012 for 29 days on a Schengen visa valid from December 1st, 2012 to February 1st, 2013 for research purposes (I am a Ph.D. student). I want to visit Sweden from February 10th, 2013 to May 10th, 2013 (89 days). I have applied for a Schengen visa again (for research). How will the 90/180 rule work in my situation?