So I would want to swap the keys y and z with each other, is there anyway to remap the keys with something like a terminal command

I want to remap § to ` and ± to ~ on my Mac keyboard because they are located in a place I am not used to. Is there an easy way to do this?


I switched to "Cycles Render" instead of "Blender Render" and my object is now fully white. I would like to render my object with it's material. I have been looking for solutions for quite some time and I'm not quite sure.

How does Cycles work and how is it different from Blender Internal?  Which is better?


In the sentence:     I'd like to watch the sun go down    why there is no "to"?  Why not:      I'd like to watch the sun to go down

Some verbs are followed by ing, e.g. I enjoy swimming. We can't say I enjoy to swim. Likewise, some verbs are followed by to, e.g. I decided to make a plan.   Which particular verbs are followed by ing and to? Can you please provide a list for that?  Moreover, which verbs can be followed by both without having the meaning changed?


I am using LyX to write my thesis. I use the document class "article", and I really want to continue doing that.  The problem is the numbering of the sections/subsections.  If it is the x. section of chapter y, I want the numbering to be like  y.x  If it is the z. subsection of section x of chapter y, I want the numbering to be like  y.x.z  Is it possible in any way?

The default in lyx is to have   I. First part (roman number)   Section 1   1.1 Subsection 1  and I'd like to have   First part (arabic number)   1.1 Section 1  1.1.1 Subsection 1  etc.   Any suggestion? Thanks a lot in advance!


Is there any check list for how to do migration from SQL Server 2008 to SQL server 2016 ?   I am building a new server for the 2016 want to move all the DBs from the old server 2008 to the 2016  any suggestions ?

We are planning to migrate to 100 TB of data from one of our client to new SQL Server environment. We just started receiving information from client. It will take couple of months to complete the project. But, can anyone please provide detail plan for migration such a large number of SQL Servers and data. New environment will have 4 fail-over cluster node at 4 different location.    Current environment: SQL Server 2008 R2 New environment : SQL Server 2014/16


I have installed Ubuntu in my chromebook but it only boots into chrome OS. My goal is to have my Chromebook booting into Ubuntu.

I have installed Ubuntu 13.04 on my desktop (runs like a charm). Then I used Crouton to install Ubuntu 12. 04 on my chromebook samsung (ARM). It also works quite well.  Here comes my question. Can we have a true Ubuntu (preferably 13.04) on my ARM chromebook?  It seems that the Crouton/Ubuntu is not 100% the real thing.  The best option would be to have the full Ubuntu 13.04 and remove the Chrome OS.


I accidentally broke my TV(Strange circumstances led to a cracked screen. I've read that it can be dangerous and deadly because there could be something called MBBA inside. It's an LG smart TV (I don't know the model or anything, it's my parents...) but it cracked and there's supposed to be liquid crystal inside. Is it dangerous? Nothing is leaking out yet, but should I get the TV out of the house? It's pretty late, and I'm tired(I've been up all night cleaning bc relatives are coming over soon) and I want to go to bed. Can I leave it in the house overnight? Please answer quickly, I want to go to sleep.

I have an LCD monitor that is cracked. So far nothing leaks out but if something starts leaking should I be concerned?   I have searched and read everything from:     It is safe to be around and handle just don't eat it.   to     It is toxic and should be avoided!   So I ask which is it? Should I be concerned if I see leakage?


This is what I needed. Practically, a link were also okay.  $$\sum_{n=1}^{\infty}\frac{1}{n^2}=\frac{\pi^2}{6}$$

As I have heard people did not trust Euler when he first discovered the formula (solution of the ) $$\zeta(2)=\sum_{k=1}^\infty \frac{1}{k^2}=\frac{\pi^2}{6}.$$ However, Euler was Euler and he gave other proofs.   I believe many of you know some nice proofs of this, can you please share it with us?


I am searching a term which means: absence of forms, bureaucracy and long procedures. I don't know if formless could be correct as long as it is a neologism.

What is the word which describes the absence of formless, of long procedure with bureaucrats? I was thinking about formsless but it sounds weird...


Prove that $$\begin{align}f\colon [0,1]&\to \mathbb{R}\\x&\mapsto f(x)=\begin{cases}0, & x\notin \mathbb{Q}\\ \frac{1}{q}, & x=\frac{p}{q} \text{ in lowest terms.}\\ \end{cases}\end{align}$$ is Riemann integrable on $[0,1]$.   My proof (is it a valid one?): All I know about this function is that $\displaystyle\forall a\in(0,1),\; \lim_{x\to a}f(x)=0.$ That is, we have that for all $a\in(0,1)$, for every $\varepsilon>0$, there is a $\delta>0$ such that, given $x\in[a-\delta,a+\delta]\setminus \{a\}$ we have $0\leq f(x)<\varepsilon$. Let $r$ be irrational (so $\frac{r}{n}$ is irrational for all natural $n$) and consider the partition $$ P_n=\left\{0,\frac{r}{n},\frac{r}{n}+\frac{1}{n},\dots , \frac{r}{n}+\frac{i}{n},\dots ,\frac{r}{n}+\frac{n-1}{n},1\right\}.$$ Note that the number on the center of every interval $\left[(P_n)_i,(P_n)_{i+1}\right]$ ought be irrational. Let $n$ be such that $(P_n)_{i+1}-(P_n)_i<2\delta$ (so that $[(P_n)_i,(P_n)_{i+1}]$ is of the form $[a-\delta,a+\delta]$ for an irrational $a$). Now, since $f(a)=0$ (for $a$ is irrational), we have that $\forall x\in [(P_n)_i,(P_n)_{i+1}],\; 0\leq f(x)<\varepsilon$ and thus $\sup\{f(x)\mid x\in[(P_n)_i,(P_n)_{i+1}] \}\leq\varepsilon$. Since this can be true for all epsilon, we have that the upper sum can be made as close to $0$ as desired. The lower sum is always $0$. We conclude that $f$ is integrable on $[0,1]$ $\square$. Is the proof valid? I claim $\forall i,\; \forall x\in [(P_n)_i,(P_n)_{i+1}],\; f(x)<\varepsilon$. This can´t be. What happened to the rational values? lol

Consider the function $f: [0,1] \to \mathbb{R}$ where f(x)= \begin{cases} \frac 1q & \text{if } x\in \mathbb{Q} \text{ and } x=\frac pq \text{ in lowest terms}\\ 0 & \text{otherwise} \end{cases}  Determine whether or not $g$ is in  $\mathscr{R}$ on $[0,1]$ and prove your assertion. For this problem you may consider $0= 0/1$ to be in lowest terms.  Here's an attempt. I may have abused a bit of notation here, but the ideas are there.   Proof: Let $M_i = \sup \limits_{x \in [x_{i-1},x_i]} f(x)$.  Notice first that the lower Riemann sums are always $0$, since every interval contains an irrational number. Thus, to prove $f \in \mathscr{R}$, it suffices to prove that, given any $\epsilon >0$, $\sum \limits_{i \in P} M_i \Delta x_i < \epsilon$ for some partition.     Let $\epsilon > 0 $ and $M  > \frac{2}{\epsilon}$. We first show that there exists $\eta(x,\frac{1}{M})$ so that $|f(x) - f(y)| < \frac{1}{M}$ if $|x-y| < \eta$. Fix $x \in (\mathbb{R} \setminus \mathbb{Q}) \cap [0,1]$. Now, consider the set $$R_{M} := \{ r \in \mathbb{Q} : r = \frac{p}{n}, n \leq M, p \leq n, p \in \mathbb{N} \}.$$ Clearly this set is finite, enumerate it as $\{q_1,\ldots, q_m\}$. So, let $$\eta(x,\frac{1}{M}) = \min_{i=1,\ldots, m} |x- q_i|.$$ We see then, $|f(x) - f(y)| < \frac{1}{M}$ on this $\eta$-neighborhood.    After we choose that $\eta$ so that $x \in (\mathbb{R} \setminus \mathbb{Q}) \cap [0,1]$, is continuous in a $\eta$-neighborhood, we see  $$ A:= [0,1] \setminus R_M \subset \left( \bigcup_{ x \in ( \mathbb{R} \setminus \mathbb{Q}) \cap [0,1]} B_{\eta(x)} (x) \right) \cap [0,1].$$  Since $A$ is compact, we may take finite sub-covering, and let $\delta = \min \limits_{i=1,\ldots,n} \{\eta(x_i)\}$. Take a partition $P_1$ of $A$ so that $\Delta x_i < \delta$. Since $R_M$ is non-empty, we can take a partition $P_2$ of $R_M$ so that $\Delta x_i < \frac{\epsilon}{2m}.$ Moreover, we see that,  on $[0,1]$, $f$ is at most $1$. Let $P = P_1 \cup P_2$. Thus,   \begin{eqnarray*} \sum_{i \in P} M_i \Delta x_i &=& \sum_{i \in P_1} M_i \Delta x_i + \sum_{i \in P_2} M_i \Delta x_i \\ &\leq& \frac{1}{M} \sum_{i \in P_1} \Delta x_i + \sum_{i \in P_2} \Delta x_i \\ &<& \frac{\epsilon}{2} + \frac{\epsilon}{2} = \epsilon  \end{eqnarray*}    Comments?    EDITED I think I resolved the issue.


I'm an avid Command Block user for Minecraft: Bedrock Edition and I'm currently diving into a system for a Boss Spawner for what's essentially an RPG-style dungeon with a Boss Spawner and boss at the end. I've spent quite a bit of time trying to piece together a command that can detect when the "boss" entity dies so as to give the player an automatic reward and to teleport them safely from the dungeon. The only problem is that the command requires the entity that I'm spawning as the boss, which is a skeleton, in this case, to have the unique name "TheMinion". I've been able to create a system that can detect the skeleton entity and apply the correct armor, weapon, and effect combination that I want, but I cannot find one that will apply a nametag to the entity.  I would greatly appreciate it if anyone could share a solution to this problem.

In Java Edition, I can name a mob by using NBT tags like this: /summon zombie ~ ~ ~ {CustomName:'{"text":"TheUndead"}'}  But in Bedrock Edition, I've heard NBT is not accessible from commands. What can I do to summon a mob with a custom name tag using the /summon command?


$\textbf{Question:}$ Let $f:\mathbb{R}\to\mathbb{R}$ be a twice differentiable function such that $$\frac{1}{2y}\int_{x-y}^{x+y}f(t)dt=f(x)$$ holds for every $x\in\mathbb{R}$ and $y>0$. Show that there exists $a,b\in\mathbb{R}$ such that $f(x)=ax+b$ for all $x\in\mathbb{R}$.   $\textbf{My solution:}$ It is given that $$f(x)=\frac{1}{2y}\int_{x-y}^{x+y}f(t)dt \hspace{0.5cm}...(1)$$ for every $x\in\mathbb{R}$ and $y>0$.   This also implies that $$2y.f(x)=\int_{x-y}^{x+y}f(t)dt \hspace{0.5cm}...(2)$$ for every $x\in\mathbb{R}$ and $y>0$.  Differentiating $(1)$ with respect to $x$ (by Leibnitz Rule), we have $$f'(x)=\frac{1}{2y}\left(f(x+y)-f(x-y)\right)$$ $$\implies 2y.f'(x)=f(x+y)-f(x-y)\hspace{0.5cm}...(3)$$ for every $x\in\mathbb{R}$ and $y>0$.   Differentiating $(2)$ with respect to $y$ (by Leibnitz Rule), we have $$2f(x)=f(x+y)+f(x-y)\hspace{0.5 cm}...(4)$$ for every $x\in\mathbb{R}$ and $y>0$.   Adding $(3)$ and $(4)$ and dividing both sides of the equality by $2$ we have $$f(x)+yf'(x)=f(x+y)$$ $$\implies f'(x)=\frac{f(x+y)-f(x)}{y}\hspace{0.5cm}...(5)$$ for every $x\in\mathbb{R}$ and $y>0$.   Again differentiating $(3)$ with respect to $x$ we have $$2y.f''(x)=f'(x+y)-f'(x+y)\hspace{0.5cm}...(6)$$ for every $x\in\mathbb{R}$ and $y>0$.   Now, by differentiating $(3)$ with respect to $y$ we have $$2f'(x)=f'(x+y)+f'(x-y)\hspace{0.5cm}...(7)$$ for every $x\in\mathbb{R}$ and $y>0$.   Adding $(5)$ and $(6)$ and dividing both sides of the equality by $2$ we have $$f'(x)+yf''(x)=f'(x+y)$$ $$\implies f''(x)=\frac{f'(x+y)-f'(x)}{y}\hspace{0.5cm}...(8)$$ for every $x\in\mathbb{R}$ and $y>0$.   Now let us take any $x=x_1\in\mathbb{R}$. Then by $(5)$ we have $$f'(x_1)=\frac{f(x_1+y)-f(x_1)}{y}, \forall y>0.$$   Now let us take any $y=y_1>0$. Then by applying MVT to the function $f$ on the interval $[x_1,x_1+y_1]$ we can conclude that $\exists c_1\in(x_1,x_1+y_1)$ such that $$f'(c_1)=\frac{f(x_1+y_1)-f(x_1)}{y_1}$$ $$\implies f'(x_1)=f'(c_1).$$   Again by applying MVT to the function $f'$ on the interval $[c_1,x_1]$ we can conclude that $\exists c_2\in(c_1,x_1)$ such that $$f''(c_2)=\frac{f'(x_1)-f'(c_1)}{x_1-c_1}=0$$ $$\implies f''(c_2)=0.$$   This implies by $(8)$ we can conclude that $f'(c_2)=f'(c_2+y), \forall y>0$.   Now by $(7)$ we have $$2f'(c_2)=2f'(c_2+y)=f'(c_2+y)+f'(c_2-y)$$ $$\implies f'(c_2+y)=f'(c_2-y)$$ $$\implies f'(c_2-y)=f"(c_2+y)=f'(c_2), \forall y>0.$$   Thus we have $f'(x)=f'(c_2)=c, \forall x\in\mathbb{R}.$   Thus we can conclude that $f$ is linear, which implies that, $\exists a,b\in\mathbb{R}$ such that $f(x)=ax+b, \forall x\in\mathbb{R}$.   Is there a better and shorter solution to this problem?

Here's the question:     Let $f:\mathbb{R}\to\mathbb{R}$ be a twice differentiable function   such that $$\frac{1}{2y}\int_{x-y}^{x+y} f(t) dt=f(x)\text{ for all  }x\in\mathbb{R},y>0$$ Show that there exist $a,b\in\mathbb{R}$ such   that $f(x)=ax+b$ for all $x\in\mathbb{R}$.     My attempt:  It immediately follows from Fundamental Theorem of Calculus that $f'(x)=\frac{1}{2y} \left( f(x+y)-f(x-y) \right)$ for all $x\in\mathbb{R},y>0$.  Let $x\in\mathbb{R}$ and $y>0$ be arbitrary. Then there is a $c\in(x-y, x+y)$ such that $\frac{f(x+y)-f(x-y)}{2y}=f'(c)$. But $\frac{f(x+y)-f(x-y)}{2y}=f'(x)$ hence,  $f'(x)=f'(c)$. But since $x$ was arbitrary, $f'(x)=f'(c)$ for all $x\in\mathbb{R}$. Hence, it follows again by Fundamental Theorem of Calculus that $f(x)=f'(c)x+f(0)$ for all $x\in\mathbb{R}$.    It appears to me as if my proof is correct but I never used the "twice differentiable part". Are there any flaws in my proof? Alternative proofs are welcome.    EDIT: As pointed out by , my proof is wrong. Hints would be appreciated.


I would like to show that $P(X)=X^4-20X^2+16$ is irreducible on $\mathbb{Q}$, how to proceed ?

Prove that $f=x^4-4x^2+16\in\mathbb{Q}[x]$ is irreducible.  I am trying to prove it with Eisenstein's criterion but without success: for p=2, it divides -4 and the constant coefficient 16, don't divide the leading coeficient 1, but its square 4 divides the constant coefficient 16, so doesn't work. Therefore I tried to find $f(x\pm c)$ which is irreducible:  $f(x+1)=x^4+4x^3+2x^2-4x+13$, but 13 has the divisors: 1 and 13, so don't exist a prime number p such that to apply the first condition: $p|a_i, i\ne n$; the same problem for $f(x-1)=x^4+...+13$ For $f(x+2)=x^4+8x^3+20x^2+16x+16$ is the same problem from where we go, if we set p=2, that means $2|8, 2|20, 2|16$, not divide the leading coefficient 1, but its square 4 divide the constant coefficient 16; again, doesn't work.. is same problem for x-2  Now I'll verify for $f(x\pm3)$, but I think it will be fall... I think if I verify all constant $f(x\pm c)$ it doesn't work with this method...  so have any idea how we can prove that $f$ is irreducible?


Right now I have a base mesh of a human with a basic rig structure, I am trying to have him point a finger gun but whenever I raise the characters arms the mesh twists. (see below)    I don't know what is causing this but I have good topology and the rig vertex groups are all pretty good. any ideas?

I'm trying to work out this shoulder deformation. I can't figure it out.  Is there anything wrong in my armature? Should i add bones and keep more control of my mesh or use shape keys? Here is my file blend.


can a method be declared with static type argument in java ? if no, why?  ex:   class A {     void m(static int x)     {          System.out.println(x);     } }

To be specific, I was trying this code:  package hello;  public class Hello {      Clock clock = new Clock();      public static void main(String args[]) {         clock.sayTime();     } }   But it gave the error      Cannot access non-static field in static method main   So I changed the declaration of clock to this:  static Clock clock = new Clock();   And it worked. What does it mean to put that keyword before the declaration? What exactly will it do and/or restrict in terms of what can be done to that object?


The goal is to selectively configure a single page of a multi-page document to:    and paper size A3.     The hope is that the link is dated and that the community has found solutions to enable implementation of the line-items.  If both are not possible for a single page, it would still be a 'win' if either was possible.   If this is not possible, I would encourage readers to send a feature request to Google and up vote the question to signal interest in the feature (maybe Google will take notice).

I have a really large table and I need to add it to a portrait document. Is there any way to make a single page landscape in Google Docs?   In Word you could add a "Section break" and do that. But I'm working on a document with my friend and I can't just use Word.


How can I prove the that the statements,  (i) $aha^{-1} \in H$ for each $h \in H$  (ii) $a^{-1}ha \in H$ for each $h \in H$  are not equivalent for any particular $a \in G$? I have been trying to come up with a counterexample but I have been unsuccessful. Evidently I would need to find an infinite group which satisfies this, since inductively,  $ \forall h \in H ( aha^{-1} \in H ) \implies \forall h \in H \; \forall n \in \mathbb{N}^+ (a^n h a^{-n} \in H)$  As was pointed out by user Robert Shore.

Let $G$ be a group, $H\subseteq G$ a subgroup and $a\in G$ an element of the group. Is it possible that $aHa^{-1} \subset H$, but $aHa^{-1} \neq H$?   If $H$ has finite index or finite order, this is not possible.


We have a database which is set up in Merge Replication.  We accidentally updated hundreds of thousands of records in a large published table on the publisher database.  We did is something like this:-  update LargeTable set Field=Field   So basically, every record got updated to be the same - no data was actually changed. However, every record in the table is now being delivered to every subscriber and the whole system has come to a halt. We are very worried this will take days and days to complete.  How can we safely remove data from the msmerge_contents and msmerge_genhistory table? Are there other system replication tables to remove records from? I can see the exact records in these tables that refer to the mass update. I just don't want to remove them without knowing it is safe to do so.

We have a database which is set up in Merge Replication.  We accidentally updated hundreds of thousands of records in a large published table on the publisher database. We did something like this:  update LargeTable set Field = Field   So basically, every record got updated to be the same - no data was actually changed. However, every record in the table is now being delivered to every subscriber and the whole system has come to a halt. We are very worried this will take days and days to complete.  How can we safely remove data from the msmerge_contents and msmerge_genhistory table? Are there other system replication tables to remove records from? I can see the exact records in these tables that refer to the mass update. I just don't want to remove them without knowing it is safe to do so.


Current working directory is PATH2 ARG2=3 $ for i in {1..$ARG2}   do     cd FIXBILL_$i     cp output.txt $PATH1     cd $PATH1     mv output.txt output_$i.txt     cd $PATH2  done  sh[3]: FIXBILL_{1..3}:  not found. cp: cannot access output.txt: No such file or directory mv: output.txt: cannot access: No such file or directory  it should take FIXBILL_1 , FIXBILL_2 & FIXBILL_3 but instead its taking FIXBILL_{1..3}. Please help.

I want to use $var in a shell brace expansion with a range, in bash. Simply putting {$var1..$var2} doesn't work, so I went "lateral"...   The following works, but it's a bit kludgey.    # remove the split files echo rm foo.{$ext0..$extN} rm-segments > rm-segments source rm-segments   Is there a more "normal" way?


pdflatex generates a lot of files that are of no use to me but are important to pdflatex (.aux, .fls, .log, .nav, .toc etc). How can I hide these files, e.g by putting them in some other, global directory? I don't want to see them when using LaTeX normally.  latexmk has the -auxdir option, but it only works with MiKTeX.

When compiling with pdflatex we need the *.aux files in a separate folder.


I am reading the Lord of the Rings again, and this quote by Saruman     'Later!' he cried, and his voice rose to a scream. 'Later! Yes, when you also have the Keys of Barad-dûr itself, I suppose; and the crowns of seven kings. and the rods of the Five Wizards, and have purchased yourself a pair of boots many sizes larger than those that you wear now.   caught my attention. A while ago, someone was telling me that there were five wizards: Saruman the White, Gandalf the Grey, Radagast the brown, and two others, the Blue Wizards. It seemed from the following conversation that nothing was known about them.  Who are the other two, the Blue Wizards?

All I've ever been able to find is that they arrived in Middle-earth and left to go do something outside of the scope of the story. Has anyone ever found any additional information?


What does eigen vector with largest eigen value mean and how it has effect on covariance matrix?

In today's pattern recognition class my professor talked about PCA, eigenvectors and eigenvalues.   I understood the mathematics of it. If I'm asked to find eigenvalues etc. I'll do it correctly like a machine. But I didn't understand it. I didn't get the purpose of it. I didn't get the feel of it.        I strongly believe in the following quote:     You do not really understand something unless you can explain it to your grandmother. -- Albert Einstein   Well, I can't explain these concepts to a layman or grandma.   Why PCA, eigenvectors & eigenvalues? What was the need for these concepts? How would you explain these to a layman?


How much reputation/points does one need to have in order to add a comment to a question?  Suppose, I see a question, but i do not want to answer it..all i want to do is add a comment on that question to ask for some details like asking the user to share some more code/inputs or stuff like that! So how much point/reputation do i need so that I get to see a      "add comment"   link below each each and every question i come across?   I would be glad if someone can share any inputs on this.  Thank you.

Across the Stack Exchange network you may leave comments on a question or answer.  How do comments work? What are comments for, and when shouldn't I comment? Who can post comments? Who can edit comments? How can I format and link in comments? My comment doesn't contain some of the text I typed in it; why? My comment appears to be long enough, but I can't post it because it's too short; why? Who can delete comments? When should comments be deleted? Why can't I comment on specific posts even if I have enough reputation to comment? When can comments be undeleted? What are automatic comments? How can I link to comments? Anything else I should know about comments?  Also see the FAQ articles on  and .


Let $R$ be the usual topological space and $A$ be a countable subset of $R \times R$.   How to show that $(R \times R) \setminus A$ is path connected?

Here's a question that I share:  Show that if $D$ is a countable subset of $\mathbb R^2$ (provided with its usual topology) then $X=\mathbb R^2 \backslash D $ is arcwise connected.


Here is my code with two tikzpictures. I was expecting both to produce similar output.  \documentclass{article} \usepackage{tikz} \begin{document}  \begin{tikzpicture} \node[rectangle,draw,minimum size=5mm] (r0) at (0, 0) {}; \node[rectangle,draw,minimum size=5mm] (r1) at (10mm, 0) {}; \node[rectangle,draw,minimum size=5mm] (r2) at (20mm, 0) {}; \node[rectangle,draw,minimum size=5mm] (r3) at (30mm, 0) {}; \draw[->] (r0) -- (r1); \draw[->] (r1) -- (r2); \draw[->] (r2) -- (r3); \end{tikzpicture}  \vspace{20mm}  \begin{tikzpicture} \foreach \i in {0,...,3}     \node[rectangle,draw,minimum size=5mm] (r\i) at (10mm * \i, 0) {}; \foreach \i in {0,...,2} {     \pgfmathsetmacro{\j}{\i + 1}     \draw[->] (r\i) -- (r\j); } \end{tikzpicture}  \end{document}   Here is the output.    Why are the arrows in the second tikzpicture environment piercing into the boxes? What makes the code in the second tikzpicture environment different from the first one?

In a Tikz Figure, I'm doing some computation and want to print results as label of nodes. The problem is that I only need the integer part of the number to print.  I tried with round() function. It round the values correctly but they are printed with .0  \begin{tikzpicture}    \foreach \i in {1,2,3,4,5,6} {       \pgfmathparse{round(\i*100/3) }        \let\theIntINeed\pgfmathresult        \draw (\i,0) node {\theIntINeed};    }  \end{tikzpicture}  % Results: 33.0 67.0 100.0 133.0 167.0 200.0   Thank you in advance.


I'm a new Linux user, I'm using LAMP in Ubuntu 18.04, both orders run equals in appearance.  What is the difference between the next two commands:  sudo service apache2 restart   sudo systemctl restart apache2

systemd gives us the systemctl commands suite which is mostly used to enable services to start at boot time. We can also start, stop, reload, restart and check status of services with the help of systemctl.  We can do, for example, sudo systemctl enable service_name, and service_name will automatically start at boot time. We can also disable services not to start at boot time.  Is the only difference between the service and systemctl commands that systemctl can be used to enable the start of services at run time? Can we use systemctl on any service? What other significant differences are there?


For the Lorentz transformation $x \to x'=\Lambda x$,  the active transformation is $\phi(x) \to \phi'(x)=\phi(\Lambda^{-1}x)$  and the passive transformation is $\phi(x) \to \phi'(x)=\phi(\Lambda x)$.  I know that the active transformation changes the field and the passive transformation changes the coordinate.  But how can I understand the difference between these two equations, especially the second equation for a passive transformation?

I am a bit confused by the concepts of . In all the courses I am doing at the moment we do transformations of the form: $$ \phi(x) \rightarrow\phi'(x') = \phi(x) $$ and $$ \partial_{\mu}\phi(x)\rightarrow\partial' _{\nu}\phi(x') = \frac{\partial x^{\alpha}}{\partial x' ^{\nu}}\partial_{\alpha}\phi(x) $$ This is all perfectly clear to me. However, I am reading Peskin and Schoder at the moment, and they adapt an "active" point of view (their words), such that the above transformations are: $$ \phi(x) \rightarrow\phi'(x) = \phi(\Lambda^{-1}x) $$ and $$ \partial_{\mu}\phi(x)\rightarrow\partial _{\mu}(\phi(\Lambda^{-1}x)) = (\Lambda^{-1})^{\nu}_{\mu}(\partial_{\nu}\phi)(\Lambda^{-1}x). $$ I don't understand how to interpret this and especially how to derive the second equation.


First, my apologies in advance: this isn't really the type of question StackOverflow is intended for, but I don't know where else to ask.  Looking at the documentation for Java enum, I see this:  class Enum<E extends Enum<E>>   Please help me understand the grammar and semantics here.  I understand that <E extends X> means that the formal type E has to be actual type X or a subtype of X. In this case, X is Enum<E> and that's where my mind loses the thread, since we're defining Enum, and it's the same E.  I bumped into this looking into Enum but my question applies regardless of the class name.  I've studied the Java tutorials on generics but don't see this addressed.  I've looked at the Java language specification in various places but don't see where this kind of recursion is discussed, though perhaps I'm just missing it.

I thought I understood Java generics pretty well, but then I came across the following in java.lang.Enum:  class Enum<E extends Enum<E>>   Could someone explain how to interpret this type parameter? Bonus points for providing other examples of where a similar type parameter could be used.


Let's say I am given to CSPRNGs: RNG1 and RNG2. I want to select the best one of the two for cryptography. How should I do it? Any of the two RNGs can be initialized with a secret key during tests and any number of bytes can be generated from each RNG. Are there statistical test suites already out there for this purpose?

Are there any realties tests or criterias that prove the security of the PRNG? What kind of tests or criteria?


I have the following expression:   <bean class="java.net.InetAddress" id="inetAddress" />  <bean id="dataSource"       class="org.apache.tomcat.jdbc.pool.DataSource"       p:driverClassName="org.postgresql.Driver"       p:url="#{'jdbc:postgresql://' + inetAddress.getLocalHost().getHostName()=='alex-HP-290-G1-SFF-Business-PC'?'localhost':'172.18.0.2' + ':5432/infostock'}"/>   This expression    inetAddress.getLocalHost().getHostName()=='alex-HP-290-G1-SFF-Business-PC'?'localhost':'172.18.0.2'   must compare hostname-value (retrieved from getHostName) with 'alex-HP-290-G1-SFF-Business-PC'. If true, it returns 'localhost', otherwise '172.18.0.2'.  Actual value of hostname is 'alex-HP-290-G1-SFF-Business-PC'. I get this from:   System.out.println(InetAddress.getLocalHost().getHostName());   So, ternary operator must return 'localhost'  But it returns  '172.18.0.2'.

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


How and from where can I download skype for ubuntu 16.04 32bit machine and how can I install it?

I'm having trouble installing Skype. I have Canonical Partners enabled in Synaptic Package Manager, but skype is not showing in the search. If I try to install via:  sudo apt install skype   I get:   E: Unable to locate package skype   I went to the Skype web site and it offered a .deb file only in 64 bit.


here is a picture of the shape i would like to make in blender i have no clue how to even begin making it. what i want to know is how to make this shape in blender so i can use it for a project im doing. i tried adding a cylinder but then i could not figure out how to get the cylinder to be cut in half.

I am having a tough time building a half cylinder and have not found any tutorial showing me how to do that.


I hit the reputation cap in S.O. Actually by more, I had 194 rep when the last upvote gave me 6 points (to be 200). I got the bronze badge, but didn't get the R-E-S-P-E-C-T hat.  I got most of the points that day by edits. Is that the reason?

After slaving away on meta, I finally hit the rep cap yesterday. By "slaving away", I mostly mean making an , but whatever. I got my first meta Mortarboard, and was expecting a shiny(?) black ribbon to go along with it. I think it would look rather dashing pinned to my fedora. Even if it doesn't, it would add to my hat-count, which is sorely lacking.  So I waited. As I know, it's always a caching issue. But alas, after a couple hours passed with no sign of a ribbon, I grew despondent.  So I waited. After all, many things around here happen at the end of the UTC day. I know, I know, apparently , but I had to find out for myself. Of course, you can guess how this turned out for me.  My next thought was to search for others with the same problem. The only post I found was someone reporting , which is obviously not the same issue.  Then, I thought maybe it just isn't awarded on meta sites. After a , I ruled this out as well. MSO being special and all, it appears that several users have earned it here.  Seriously, how do I get this thing? It's not a secret hat, and the description is brutally straightforward.


Here's where I'm stuck up. I've a old file (Fieldart_1.2.war). And I've a new file named Fieldart_1.4.war. I just have to deploy the new one. But, before that I need to make sure I'm hitting the right file.  Is there anyway I can compare just the first part of the two files i.e., 'Fieldart' ? like, if the first part matches, go ahead with the deployment otherwise, throw an error..   What do you guys think ?

Given a string file path such as /foo/fizzbuzz.bar, how would I use bash to extract just the fizzbuzz portion of said string?


I need a hint to solve prove $\sin^2(6x)-\sin^2(4x) = \sin(2x)\sin(10x)$  I tried several solutions, including taking $(\sin(6x)+\sin(4x))(\sin(6x)-\sin(4x))$ but every time I ended up with a ridiculously large equation, I'm sure there is a more elegant way to solve this.  Note: I'm looking to go from the L.H.S to the R.H.S.

How would I verify the following double angle identity. $$ \sin(A+B)\sin(A-B)=\sin^2A-\sin^2B $$ So far I have done this. $$ (\sin A\cos B+\cos A\sin B)(\sin A\cos B-\cos A\sin B)  $$But I am not sure how to proceed.


My Stack Overflow's login email is an email address that no longer exists. While I have changed the email address in my profile, is it possible to change the login email to the new email in my profile?  edit of an edit - I've only now just realised stack exchange logins are openID's and explanation of this rather than just slapping duplicate on it without saying anything might have been clearer...

I no longer use the service that I originally used to register, and would like to change the service I use to log in, or at least add a second account.  Is this possible? How do I change my login provider or associate a backup method to log in?     For more information, see "" in the .


There are many questions opening with I am new to this and that. It seems very meta and irrelevant. It's not like I'll you will act differently to a noob question according to the faq:     Etiquette      Civility is required at all times; rudeness    So the question is should I edit it out? is it constrictive in any way?  I believe it should be treated like 'hi' and 'thanks' and same arguments against those apply: Wastes space on preview, irrelevant,not broad,etc'

starts with      I know that this isn't the first post with this problem, but I am   stuck with this for a day (total, not 1 day in a row). Somehow I can't   get this to work, maybe it is just 1 little adjustment that I need to   make, but I can't seem to find it :(   I'm sure the question , both for immediate answering and for people later having the same kind of problem.  But I'm afraid removing it might be considered rude by the asker as he might see the question with the introduction both more humble and more accorded to his personal writing style (especially in a case where the code follows immediately after this introduction).  Should I proceed and remove this lengthy useless introduction or just not bother ?


I have an Indian passport with a US work permit. I am traveling back to india via Istanbul. Do I need a transit visa to enter the city for sightseeing? For how long is a transit visa valid?

I am an Indian (Indian Passport) presently in Kano, Nigeria on a business visa. I am going back to Mumbai on 22 Sept by Turkish Airlines with a 12 hour layover time in Istanbul.  We plan to see the city during this time.  Can I get a visa on arrival?


I am confused about the wave function of a free particle  $$\psi(x,t)=A\exp \{ i(kx-\omega t)\}$$  How does this satisfy the normalization condition? Since this corresponds to a plane wave, what meaning does the probability have?

I have the one dimensional free particle Schrödinger equation  $$i\hbar \frac{\partial}{\partial t} \Psi (x,t) =  -\frac{\hbar^2}{2m} \frac{\partial^2}{\partial x^2} \Psi (x,t), \tag{1}$$  with general solution  $$\psi(x,t) = A e^{i(kx-\omega t)} + B e^{i(-kx-\omega t)}. \tag{2}$$  I'd expect that the solution is normalized:  $$ \int_{-\infty}^\infty |\psi(x,t)|^2 dx = 1. \tag{3}$$  But   $$|\psi(x,t)|^2 = \psi(x,t)\psi^* (x,t) = A^2 + B^2 + AB ( e^{2ikx} + e^{-2ikx} ), \tag{4}$$  and the integral diverges:  $$ \int_{-\infty}^\infty |\psi(x,t)|^2 dx = \frac{AB}{2ik} (e^{2ikx} - e^{-2ikx})\biggl|_{-\infty}^\infty + (A^2+B^2) x\biggl|_{-\infty}^\infty. \tag{5}$$  What is the reason for this? Can it be corrected?


The phone is a Moto G running Android 4.4.4. The problem happens when trying to install Facebook.  I've tried clearing the cache for Google Play Services and Google Play Store. The "Uninstall updates" button in Google Play Services is greyed out.  How can I fix this issue? Thank you very much.

Whenever I try to update an app, I get the error in the question title. I am also unable to view my installed apps. I've already tried wiping the store's data and cache, and removing and readding my account. Nothing helps.   I'm using a Droid Turbo running 4.4.4. Anyone know what the problem is?


The question: If $\alpha ,  \beta$ are complex numbers where $\alpha \ne \beta$ and $|\alpha|=1$. Prove that $|\frac{\alpha \overline{\beta}-1}{\alpha-\beta}| =1$

$Q.14)$ If $\alpha,\beta$ are complex numbers where $\alpha\ne \beta$ and $|\alpha| = 1$. Prove that $\displaystyle\left|\frac{\alpha\overline\beta-1}{\alpha-\beta}\right|$. .  For $Q.14$ I tried separating the expression into real and imaginary components and then solving it but it does not lead to anywhere. What approach should I take to solve this question? Thanks.


Spin comes from Dirac's theory. Does it only comes from the fact that relativistic Dirac equation is Lorentz invariant?

I study physics and am attending a course on quantum field theory. It is hard for me to draw connections from there to the old conventional theories.  In quantum field theory spin originates from the Dirac equation in the case of fermions.   I don't remember where it comes from in quantum mechanics. I just remember that there was the Stern Gerlach experiment where you shoot neutral spin 1/2 Ag atoms in. Is there also a electrically neutral elementary particle? If this is the case, how would this experiment look like in quantum field theory? Of course I ask this for the lowest order, otherwise we would have to calculate an infinite number of Feynman graphs, won't we?


I have read theories and articles about it but didn't get much(not a scientist though).  Can somebody explain to me, most possibly in easy language and terminology that why a person's time will slow down if he rotates around a blackhole, as compare to the person present on earth?  Thanks before for help and explanation. :-)

How exactly does time slow down near a black hole? I have heard this as a possible way of time traveling, and I do understand that it is due in some way to the massive gravity around a black hole, but how exactly does that massive gravity slow down time?


This 'question' is more of a possible solution to others who were in the same scenario that I was stuck in for a few days.  I had a file that had been created after a failed software install, inside two folders which were owned by a special 'shared' user who cannot login - it's just a way to access network shares without my main account details.  I tried all the usual solutions, take ownership, third party programs, delete from command line - nothing was working... the file apparently didn't exist whenever I tried to delete it, and deleting folders gave permissions errors regardless of owner.

I recently upgraded my workstation from XP SP3 to Vista Business, and during the upgrade Windows moved my old C:\Windows directory to C:\Windows.old.  I got all of the stuff I needed out of that folder, but there are six "undeletable" files there so I cannot remove it.  They are:  Windows.old\Program1\Adobe\Reader 9.0\Resource\CMap\Identity-H Windows.old\Program1\Adobe\Reader 9.0\Resource\CMap\Identity-V Windows.old\Program1\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelper.dll Windows.old\Program1\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll Windows.old\Program1\Common Files\Adobe\Acrobat\ActiveX\AcroPDF.dll Windows.old\Program1\Common Files\Adobe\Acrobat\ActiveX\pdfshell.dll   Whenever I try to delete the files either through explorer or a command line, I get a permission denied error.  I have tried to grant myself full permission on the files, but again, permission denied.  I don't even have acrobat installed on my Vista machine, and I uninstalled Adobe updater.  However, I still can't manage to get rid of these files.  How do I nuke them for good?  Edit: I was able to take ownership of the files, but I still can't delete them.  Renaming them did not work, as I was denied permission to do that as well.  I'll try booting up in safe mode and getting rid of them there.  Edit II: Booting up into safe mode did not allow me to delete the files.  Bummer.


A value of 324 is provided without explanation in a linear regression tutorial that I'm following. I checked to see if this was the number of samples, but they did not match.   Edit: My apologies for such an ill-formed question. The random_state argument is for scikit-learn's train_test_split function.   From the documentation, "If int, random_state is the seed used by the random number generator" so I can see that generating a random number is involved and I'm fairly certain that the utility of generating random numbers is to randomize the samples allocated to training/testing, but what I don't understand is why 324 was chosen.   The tutorial is here:

In almost all of the analysis work that I've ever done I use:   set.seed(42)    It's an homage to Hitchhiker's Guide to the Galaxy. But I'm wondering if I'm creating bias by using the same seed over and over.


How do I align subscripts? When doing the following, the subscript are not on an line (becasue of the ^T): \documentclass[10pt,a4paper]{article} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb}  \begin{document}          $$X_1^TX_1$$      \end{document}

When i put the code $(f_{\mathcal{X}},f_{\mathcal{X}}^{\partial})$ I get the following:  But I want the subscripts to be aligned. How can I do this?


This is about Automapper 9. Let's say you have two classes like   public class Entity {   public byte[] RowVersion { get; set;  } public class Model {   public byte[] RowVersion { get; set;  } // mapping CrateMap<Entity, Model>().ReverseMap();   When mapping, AutoMapper would simply copy array's reference to target. Which works for me, but only when projection is in direction from Entity to Model. When mapping Model back to Entity, I'd like to copy the array by value instead. Using a  won't work since it has collateral effects as it is a global converter. A  won't work either, since you can't access the target property, but just return a (new) instance of byte array. Ideally I would use a type converter on a CreateMap (without ReverseMap) but I doubt that's possible.  So I'm a bit stuck on how to do it properly.

I want to do something like:  MyObject myObj = GetMyObj(); // Create and fill a new object MyObject newObj = myObj.Clone();   And then make changes to the new object that are not reflected in the original object.  I don't often need this functionality, so when it's been necessary, I've resorted to creating a new object and then copying each property individually, but it always leaves me with the feeling that there is a better or more elegant way of handling the situation.  How can I clone or deep copy an object so that the cloned object can be modified without any changes being reflected in the original object?


I'm on mac with MAMP.  I've tried to follow this :  and this :   settings.local.php (i have not cut off comments in my file) :  assert_options(ASSERT_ACTIVE, TRUE); \Drupal\Component\Assertion\Handle::register(); $settings['container_yamls'][] = DRUPAL_ROOT . '/sites/development.services.yml'; $config['system.logging']['error_level'] = 'verbose'; $config['system.performance']['css']['preprocess'] = TRUE; $config['system.performance']['js']['preprocess'] = TRUE; $settings['cache']['bins']['render'] = 'cache.backend.null'; $settings['cache']['bins']['dynamic_page_cache'] = 'cache.backend.null'; $settings['extension_discovery_scan_tests'] = TRUE; $settings['rebuild_access'] = TRUE; $settings['skip_permissions_hardening'] = TRUE;   in y settings.php i've uncommented this :   if (file_exists(__DIR__ . '/settings.local.php')) {   include __DIR__ . '/settings.local.php'; }   developpement.services.php :  services:   cache.backend.null:     class: Drupal\Core\Cache\NullBackendFactory parameters:   twig.config:     debug: true     auto_reload: true     cache: false   I call the address localhost:8888/mysite/core/rebuild.php (in my conf/performance i've uncheck cache and i have clear all caches). But when i go to another page github signale me that i have new caches files :

I did  step by step ( also finally rebuild the cache) but yet my changes in twig files not take effects without rebuild the cache.  sites/default/services.yml :  parameters:     session.storage.options: { gc_probability: 1, gc_divisor: 100, gc_maxlifetime: 200000, cookie_lifetime: 2000000 }     twig.config: { debug: true, auto_reload: true, cache: false }   sites/default/settings.php :   if (file_exists(__DIR__ . '/settings.local.php')) {    include __DIR__ . '/settings.local.php';  }   sites/default/settings.local.php :  $settings['container_yamls'][] = DRUPAL_ROOT . '/sites/development.services.yml'; $config['system.performance']['css']['preprocess'] = FALSE; $config['system.performance']['js']['preprocess'] = FALSE;   sites/development.services.yml :  services:   cache.backend.null:     class: Drupal\Core\Cache\NullBackendFactory parameters:   twig.config:     debug: true     auto_reload: true     cache: false   Where is the Problem?


Mass apart from the amount of material, is also a measure of the inertia of an object, ie. the resistance to change its motion. In zero gravity, does still mass count as the amount of inertia? In other words, the resistance to move a rock is the same in zero gravity and on earth, if there is no friction etc?

I have demonstrated that  only is measured based on the gravitational pull of where you live.  For example, the gravity on the surface of Mars is three times smaller than the gravity on the surface of Earth.  So my question is simple: If we take into account that weight is only measured based on gravitational pull on that , if there was no gravity how would we define mass?  That is, would mass weigh anything if no gravitational pull acted on it? Then what would be mass?


What's a word for the feeling of liking something, but not liking it at the same time? I love the way the Spanish speak, but it bothers me at the same time. I've looked through and dictionaries asked teachers, but i can't seem to find the right word. I would really appreciate the help, thank you.

I've been trying to think of an adjective that expresses having two (or perhaps more) conflicting emotions or opinions simultaneously. Can anyone think of one?


Let $f : \mathbb{R} \to \mathbb{R}$ be differentiable function.     If $\lim_{x\to \infty}f(x) = 0$ , then $\lim_{x \to \infty} f^{'}(x) $ exists?   I think the answer is No.  Because I think there may exists function $f$ alternanting its sign as $x \to \infty$.  Could you give me a such function or Prove above statement?

Let $f: \mathbb{R} \rightarrow \mathbb{R}$ a differentiable function with continuous derivative and the limit $\displaystyle{\lim_{x \rightarrow +\infty} f(x) }$ exists. Show  with an example that it is possible that the limit $\displaystyle{\lim_{x \rightarrow +\infty} f'(x)} $ does not exist.  My attempt:  $$f(x)=\int_{-\infty}^{x} e^{t^2}dt$$  $$\lim_{x \to +\infty} f(x)=\lim_{x \to +\infty} \int_{-\infty}^{+\infty} e^{t^2}dt=\frac{\sqrt{\pi}}{2}$$  $$\lim_{x \to +\infty} f'(x) =\lim_{x \to +\infty} e^{x^2}= +\infty \notin \mathbb{R}$$  Is my attempt right?


I initially believed that this was the original backstory for Marvel's X-Man  before they settled on a more vague triggering of the X-gene, but I have found no references online indicating as such, which makes me think this was another work that I conflated to Angel in my head. The protagonist develops wings, and it turns out they're physiologically built for it, everything from hollow bones to specially adapted lungs to be able to breathe at high altitudes. It's indicated in the story that the mutation was caused by his parents (scientists?) being exposed to the fields from high voltage. Unfortunately, maybe because my brain associates this with the X-Men character, I don't really remember much of the plot, including what happens to him once he realizes that he can use his wings to fly. I read this as a child in Ashland, KY, which means likely somewhere around the mid 1980s to the mid 1990s, in English, and I suspect it's a short story, based on the paucity of information and vague hints in my head. I do not believe it to be Black and Blue Magic by Zilpha Keatley Snyder as he gains his wings later in the story by magical means. It might have been a story in Isaac Asimov's Young Mutants or a contemporaneous book. Unfortunately, it might as well have been from an anthology of science fiction, of which I read many growing up, between the library and my father's collection.

I read this a long time ago as a child. It was in a collection of short stories, maybe some kind of scifi anthology.  It was about a man with wings who flew over a farm and was shot down by the farmer, mistaking him for some bird, I think. His daughter nursed the man back to health, they ended up getting married but he had to cut off his wings. Some time in the future, his wings begin to grow back and he decides to fly but his wings are not strong enough to support him. He ends up falling into a lake (or some body of water) and the story ends.


I'm looking for a fantasy novel that has the back story of having two great elemental magic users (not sure what they are called in the novel).  One can use fire and earth, the other water and air.  They join forces to defeat demons.  The novel starts long after that has ended, and only one remains.  The demons are posing a threat again so the master seeks an apprentice, fusing him with a gem to grant him power.  The gem tries to gain control of the boy, but the boy emerges with the power instead.  It is then learned that the gems are actually technology from a long-lost race, and the demons are actually aliens.

I read this book a long time ago, but I'm guessing it was written sometime in either the 80's or early 90's. It was a rather long/large book.  Plot summary: Set in a fantasy land of wizards and magic, some kids (maybe) are recruited to learn magic. In the process they find out that wizards are created by being placed in a crashed spaceship that bonds them with crystals that imbue the powers. One of them is able to bond with many/multiple crystals to become very powerful.


I have an old password protected RAR file with a random generated password that I lost. I still have some of the files outside, but need the rest.  Is there a way to obtain the password by comparing the same file, inside and outside the RAR?  Btw, filenames and attributes of my RAR luckily are not hidden, and all the files are protected with the same password.

Does the  file format use a serious encryption (such as )?  Will it take unfeasibly long to brute force a password?  If not, what tools do you suggest that do so automatically?


I want to create a shortcut for a command in terminal. Like for a command  "ssh user@123.45.7.123", I just want a command "user" and the above command will run. Is this possible, and if so how can it be done?  Thank you!

By typing a manually specified command in terminal I want to execute some other command.  How could add an alias to a command? Can i do that with the help of the terminal or should I edit some kind of file?


guys, currently I'm working on a project where I need to load some data through AJAX. I'm using jQuery for AJAX. Here are the HTML and JavaScript code  <body> <input type="submit" value="Number 1"> <script src="jquery.js"></script> <script>     $(document).ready(function(){         $.ajax('ajax.html',{         success: function(data){             $('body').append(data);         }         });          $('input').click(function(){             alert('bang!!!');         });      });  </script> </body>   And here is the ajax.html file  <input type="submit" value="Number 2">   Now the AJAX is working perfectly, but the click event is not working with the AJAX loaded input tag  The click event is working perfectly with the first input tag

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.


What is the difference between STM and USM in a lens? What's the major difference?  Is this only for a Canon user, or Nikon, or else DSLR also having same types lenses?  What should I choose for day-to-day photography and basics ?

The  has a designation of STM on the lens. What does this mean? What are the advantages of having it and does it replace an older technology?  We have a  that usually covers these questions but this is not yet addressed in it.


It seems clear to me that when I'm in a community with "hard questions" (ie. ones that have clear answer) it makes sense to me that I should accept the best and fastest answer.   However, for a community with more "soft questions" (ie. ones that do not have clear answers) I am wondering if there are some guidelines to follow, or some common practice, for how quickly to accept answers.

I have noticed that some questions get a lot of responses quickly, and the cool fact is that most of the time these initial responses are correct.  I see users are motivated to accept answers. Because many questions take less than 24h to get an acceptable response, I'm unsure what to do when I have a question that takes more than 24h to get a response that I feel is complete enough to warrant being marked as accepted.  And even for acceptable responses, I often hesitate to accept them out of concern that posters will pass my question by if it already has an accepted answer (unless it has lots of upvotes). Does this really deter the higher-quality posters, though?


I'm using \includegraphic{image.pdf} to insert an image into a Beamer presentation. The image that I have is a drawn diagram that was scanned. Part of the diagram is sketched in light blue which looked alright on the piece of paper but is washed out by surrounding white paper around it once scanned.   Is there a way in beamer to darken all colors of an pdf image?

I have a graphic in PDF format (originally converted from an SVG) that is monochromatic (black on white). Is it possible using TikZ or PSTricks but not (Illustrator or Inkscape) to include this image in a different color?  Example:    While it lasts (there seems to be no long term way to host a pdf), you can .  Edit: Simple was perhaps a bit of a misnomer - the pdfs are cropped and monochromatic, but to intricate to redraw on my own. The above example is a character from a font (which I can recolor), but it gives a good example of what shapes I am talking about.


I want to know the storage location of apt-get download command in Ubuntu.

As time goes by we tend to do apt-get install and add or replace software.  Are these archived in some form or do they get auto-cleared after installation? And if it doesn't get auto-cleared, it would mean that a clean up is needed, isn't it?  Finally, if they're not auto-removed, can we reuse these packages on different machines?


Can any one explain me to how to configure VPN server in Ubuntu 14..? am about to deploy a VPN server for my firm next week please help me.. Thank you in advance.

I know there are many tutorials on the net for setting up VPN client and server.  I you find one that is simple/short, I am interested only in the server part.   For client, I will use OS X so I prefer a solution that uses L2TP over IPsec or PPTP because I suppose Cisco IPsec would cost something.  I don't want to spent too many hours setting it up. You know, maybe someone already made a setup script :)  Note: I am using an EC2 micro instance running Ubuntu 12.04 on it.


Let a positive integer n be called a super exponential number if its prime factorization contains at least one prime to a power of 1000 or larger. Prove or disprove the following statement: There exist two consecutive super exponential numbers.

Say that a positive integer n is highly exponential if there is an exponent greater than or equal to 1000 in its prime factorization. Can there exist two such numbers consecutively?


How to find an expression for the below summation series? $ \sum\limits_{i=1}^\mathbb{n}(-1)^{i-1}i^2 $

Please look at this expression:     $$1^{2}-2^{2}+3^{2}-4^{2} + \cdots + (-1)^{n-1} n^{2}$$   I found this expression in a math book. It asks us to find a general formula for calculate it with $n$.  The formula that book suggests is this:      $$-\frac{1}{2}\times (-1)^{n} \times n(n+1)$$   Would you mind explaining to me how we get this formula?


Is there any transformation that can match two circles with equal radii (say $r_0$) which are positioned at $(0,0)$ and $(X_0, Y_0)$  to two concentric circles? I know there is a transformation when  $Y_0$ is equal to zero, but I need both $X_0$ and $Y_0$ to be nonzero. The initial circles do not collide which means $X_0^2+Y_0^2>>4 r_0^2$. I should also note that I don't like to use rotation to make $Y_0$ equal to zero because my boundary condition is difficult. What is the transformation that can do the job?

Show that two non intersecting circles can always be mapped by a suitable Möbius transformation to two concentric circles.  I wanted to map the center of the first circle to the center of the second circle then using scaling the radius would give me the concentric circles. But having problem to execute.  Suggestions please,


If $f:X \to \mathbb{R}$ is a continuous non constant function and $(X,d)$ is a connected metric space then $X$ is uncountable.   How to proceed this proof I am clueless , I know that if $X$ is connected so $f(X)$ is also connected and $f$ is non constant to $f(X)$ is an interval which is not singleton, also each interval is uncountable, so, $f(X)$ is uncountable does it means that $X$ is also uncountable? Any other methods other than this to understand this question?

My question: let $f : X \to \Bbb R$ be a non-constant continuous function on a connected metric space and assume that $f(X)$ is uncountable; then $X$ is uncountable.  We know continuous image of a connected metric space is connected. Since connected space in $\Bbb R$ are intervals and the function is non-constant continuous function so $f(X)$ is an interval in $\Bbb R$ and hence uncountable.  Is the proof correct?? How does it follows that $X$ is uncountable?


I am pursuing my masters in CS and I have to come up with the dissertation topic on my own. It's very confusing to me and I am not able to come to any conclusion as to how to narrow down to specific topic in cloud computing(want to do my dissertation in this) . I know basics of cloud computing.   What can I do that will help me in narrowing down to a specific topic. My university requires me to come up with the topic and I am thinking about doing phd so I want to get my hands on research to see if I will be a good fit in phd.   My university does not have good professors who have done some good research work, so I am on my own. Can someone please help me in this situation.

If a master's degree candidate needs to select a thesis topic, but their advisor is unwilling to offer suggestions on the matter, how should one go about selecting a thesis?   How might one select an area to study? How can one evaluate if if is a suitable topic? Does the thesis need to focus on an area which is relatively unexplored by prior research?


Question: Prove that for any nonnegative integer $n$, $n^3 - n$ is divisible by $3$.  So I suppose that $n^3 - n = 3m$ for some integer $m$.  I know it is true for $n= 1$.  Suppose it is true for $n=k$. So $k^3 - k = 3t$ for some integer $t$.  How to prove it for $n= k+1$? I didn't get the equation for $n= k+1$.

As homework, I have to prove that     $\forall n \in \mathbb{N}: n^3-n$ is divisible by 6   I used induction  1) basis: $A(0): 0^3-0 = 6x$ , $x \in \mathbb{N}_0$ // the 6x states that the result is a multiple of 6, right?  2) requirement: $A(n):n^3-n=6x$  3) statement: $A(n+1): (n+1)^3-(n+1)=6x$  4) step: $n^3-n+(n+1)^3-n=6x+(n+1)^3-n$  So when I resolve that I do get the equation: $n^3-n=6x$ so the statement is true for $\forall n \in \mathbb{N}$  Did I do something wrong or is it that simple?


I know the parametric equation for a $3D$ helix is:  $x = R \cos t$  $y = R \sin t$  $z = h t$  Can somebody explain to me this parametric equation (image and equation from Wolfram) for a "Helix around helix" / Slinky:  $x = [R + a \cos(\omega t)] \cos t$    $y = [R + a \cos(\omega t)] \sin t$    $z = h t + a \sin(\omega t)$.    I don't understand what are the variables '$a$' and '$\omega$' supposed to represent. I assume '$h$' is the height?  How could I expand those equations for an $n$-number of helices? (say this is $2$ helices, what would change in the formula for $3$ helices?)  I would like to be able to generate such structures in Solid Works. I can get the simple $3D$ helix from the equations, but if I try with the "Slinky" one it only makes strange (yet beautiful) shapes.  Any help? I know this is way over my head, but the coil-made of a coil-made of a coil structure has obsessed me for quite some time now (I would like to sculpt it in real-life, but first model it in $3D$)  Thanks!

I am trying to work out a "helix in a helix" mathematically.  Intuitively I think of this as a steel cable, which is made up of a number of smaller steel cables all bound together in spiral.  If I wanted to find the length of one of the individual cables, it would be bound in a spiral in the smaller cable and then those cables bound in a larger spiral cable.  I know that if I wanted to do a helix whose ends meet, I would use the parametrization $$((a+b\cos(\omega{t}))\cos{t},(a+b\cos(\omega{t})\sin{t},b\sin(\omega{t})),t=0..2\pi$$ I've been trying to map out in my head how to, instead of curling the helix, making the helix travel in the path of a helix.  I've achieved it partially with $$((a+b\cos(\omega{t}))\cos{t},(a+b\cos(\omega{t})\sin{t},t),t=0..\infty$$ But this doesn't keep the smaller helix in tact, and turns it into a sine wave helix.  I've also tried  $$((a+b\cos(\omega{t}))\cos{t},(a+b\cos(\omega{t})\sin{t},tb\sin(\omega{t})),t=0..2\pi$$ But this gives me sort of a nautilus shape where the helix curls into itself and increases in size and curls around into itself.  What am I missing?  EDIT:  Also, what if we wanted to do this again, like a 'helix in a helix in a ... in a helix'?


Towards the end of the film adaption of Harry Pitter and The Deathly Hallows pt 2, we see that Voldemort disintegrates after losing his duel with Harry. However, in the books, Voldemort's body is left behind, and is "left apart from the bodies of those who fell in the battle."  On the night that Voldemort murdered Harry's parents, he would also, presumably, have left a body behind. What happened to it? In The Goblet of Fire, Voldemort needs Wormtail to make him a new one using dark magic, so was it cremated or buried by the ministry of magic?

At the start of Harry Potter and the Philosopher's/Sorceror's Stone Voldemort's Killing Curse backfires      due to Lily's sacrifice protecting Harry from Voldemort.   leaving Harry with his scar      and a loose piece of Voldemort's soul   and Voldemort as a loose soul, self-described as "Less than a ghost".  Voldemort was not dead, but had no physical body (until he got better in book 4).  What happened to his body?  Did it disappear?  Or was it left in the rubble of the house, alongside the bodies of James and Lily?


I'm working in javascript trying to understand when to use single quotations vs double quotations. I have noticed that when I put '' in html and then put "" in javascript for working with DOM it still works. when do I choose single quotations and when do I choose double quotaions? ex html :
list of fruits
  ex javascript: document.getElementById("p1").textContent = "Short list of fruits";

console.log("double"); vs. console.log('single'); I see more and more JavaScript libraries out there using single quotes when handling strings. What are the reasons to use one over the other? I thought they're pretty much interchangeable.


I have a script that operates on enormous files and outputs an enormous amount of content (almost 7000 lines). I need to copy the output of this to my clipboard so I can then paste it into paste2.org and make a paste. Is there a way for me to directly copy the output to my clipboard? Some operation like that of redirection for the clipboard?

Is there functionality in Unix that allows for the following: echo "Some Text" | copy-to-clipboard


I'm trying to get info from a file (it's to be used as a settings file, true or false values), using the following code:  File information = new File(aPath + "/plugins/ArenaCraft/info.acs");  ArrayList<String> info = new ArrayList<String>(); BufferedReader br = new BufferedReader(new FileReader(information)); String line; while((line = br.readLine()) != null) {      String[] sLine = line.split(":");      if(sLine[1] == "true"){          info.add("true");      }      if(sLine[1] == "false"){          info.add("false");      }      if(sLine[1] == null){          System.err.println("[ArenaCraft]  sLine[1] is NULL.");      }      if(sLine[1] != "true" && sLine[1] != "false" && sLine[1] != null){          System.err.println("[ArenaCraft]  sLine[1] is not NULL, but it's not \"true\" or \"false\".");          System.err.println("[ArenaCraft]  sLine[1] is: " + sLine[1]);      } }  br.close(); return info;   This, however, is outputting the  [ArenaCraft]  sLine[1] is not NULL, but it's not "true" or "false".   message. It then outputs, exactly,  [ArenaCraft]  sLine[1] is: true   So, I don't understand why it says it's not null or true or false. Do you guys imagine why that would happen?  The contents of the file I'm trying to read, with no encoding, follow:  notices:true   and nothing more.  Any help would be greatly appreciated, thanks in advance.

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


I am trying to use Reflection to create my objects at run time. However I keep getting  System.TypeLoadExeption     Could not load type 'x' from assembly 'y', version = 1.0.0.0, culture   = neutral PublicKeyToken=null'. I just create a new project to try it and it still wont work even though i have not changed the namespace   names.   ObjectHandle keyword = Activator.CreateInstance("NamespaceProject", "ChangeDue"); Object myObject = keyword.Unwrap();

One may not always know the Type of an object at compile-time, but may need to create an instance of the Type.    How do you get a new object instance from a Type?


I am only starting to learn JavaScript and encounered with a problem trying to understand how the prorotypes work.  I got the following code  var parent = {     city : "Cardiff",     hair : "white",     surname : "Smith",     name : "John" };  var child = Object.create(parent);{     name : "Mike" };  child.name   And when I call child.name it returns me John and not Mike. I tried to google, change the code, browsed through some reference books but still can't find the reason why am I returned John.

I'm not that into dynamic programming languages but I've written my fair share of JavaScript code. I never really got my head around this prototype-based programming, does any one know how this works? var obj = new Object(); obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test();  I remember a lot discussion I had with people a while back (I'm not exactly sure what I'm doing) but as I understand it, there's no concept of a class. It's just an object, and instances of those objects are clones of the original, right? But what is the exact purpose of this ".prototype" property in JavaScript? How does it relate to instantiating objects? Update: correct way var obj = new Object(); // not a functional object obj.prototype.test = function() { alert('Hello?'); }; // this is wrong!  function MyObject() {} // a first class functional object MyObject.prototype.test = function() { alert('OK'); } // OK  Also these  really helped a lot.


Is there a stable Mod that does not compromise on the S-pen of Note 3? Since a mod could better utilize the raw power of the device.

There are several reasons to be looking for a ROM:   Upgrading or downgrading your stock ROM Looking for firmware from a different region/language Flashing a custom ROM for different features, removing bloat, etc.   But where can one find ROMs in the first place?  What sites are likely to have the ROM I need?  ; please add to the wiki answer instead of posting separate answers.  See also:


In several contributions here on M.SE I saw notations like $$a/bc$$ where from the context one could conclude that it actually meant $a/(bc)$, not $(a/b)c$.  Both terms are obviously different in general, and the programming languages I know of have semantics  a/b*c = (a/b)*c   i.e. evaluate left-to-right.  The examples I saw all had "$b$" and "$c$" short like in $1/2x$ and did obviously not mean $\frac12x$ but $\frac1{2x}$as the context revealed.  How should one handle this? I am always avoiding such ambiguities and am writing the clunky $1/(2x)$, but then $1/2x$ could still be misread as $\frac1{2x}$.  If typesetting is available, then I'd use $\frac12x$ vs. $\frac1{2x}$ or $(2x)^{-1}$ or $0.5x$ or $0.5/x$, where the decimal expansions are ugly, IMO, even uglier for ⅙ etc.  Are there different conventions, e.g. in the U.S., Europe, Russia, Far East?  Using / vs. ÷ wouldn't help either. Never used the latter though, only know it from calculator's key for division.  The question about different conventions depending on the corner of the planet you live in or school vs. university is because there are already related questions, and their answers are far from conclusive. For example  claims $abc/xyz$ is to be read as $(abc)/(xyz)$ because "dropping the multiplication glyph (·, ×, * or whatever) binds stronger than with explicit mention, i.e. $$abc/xzy\neq a·b·c/x·y·z=abc/x·yz$$  So my question is less on which exact notation to use but rather on cultural differences and how established that juxtaposition rule is.

Given $5x/30x^2$ I was wondering which is the correct equivalent form.  According to BEDMAS this expression is equivalent to $5*\cfrac{x}{30}*x^2$ but, intuitively, I believe that it could also look like: $\cfrac{5x}{30x^2}$  I asked this question on MathOverflow (which was "Off-topic" and closed) and was told it was ambiguous. I was wondering what the convention was or if such a convention exists. According to Wikipedia the .


Where does the expression x-fold come from? And is its current usage the same as when it originated?   For example, if you fold a piece of paper n times, the thickness is not n times the original times n, but 2 to the power of n. So 5 folds means the thickness is actually multiplied by 32, not 5. Yet saying something increases 5-fold means it's 5 times greater.

The dictionary definition is     ten times as great or as much   I believe that this is a misnomer. The word seems to describe a process of folding something ten times; for example, a piece of paper. If you fold a piece of paper ten times you will get 210 or 1024 different rectangles.   I don't understand how the definition of this word came to be and how is it different from the phrase ten times?


I have Large amount of Account Records in salesforce, i want to check the particular field contain duplicates or Not using Query  For Small amount of Records finding duplicates using query:  SELECT JDE_ship_to_account_no__c, count(Id) records FROM account GROUP BY JDE_ship_to_account_no__c HAVING count(Id) > 1   For Large amount of account Records it is Displaying the empty Value , Please guide the answer to write the query for finding the duplicates for large amount of Records How to write soql query for finding duplicates for large amount of account records

I have More amount of Records in salesforce, i have created field as not Unique.So for account Records is created with duplicate Records also,I want to check how many Records contain dulplicate Records  for that I have wrote Query : I have lot of account records, i don't want to use limit for filtering the records when querying, i want to query all the records in salesforce.  But when i use:  SELECT JDE_ship_to_account_no__c, count(Id) records FROM account GROUP BY JDE_ship_to_account_no__c HAVING count(Id) > 1   for that they suggested answer for this question:    How to write a batch apex code for above scenario, account records contain duplicates or Not?  I want to check all the records whether the record contain duplicates or Not


Sir I have upgraded to 17.10 from 17.04. After that the system began to start normally.. then the screen become black I can't get it how to resolve this problem.... plz can anyone help me to get rid of this problem... I am using dell vostro laptop . And intel i3 processor with intel graphics card HD 520 (skylace GT2)

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


When I transfer.wav files off a music CD to my /Music folder on my hard drive the metadata (song/artist information) is not present. I can look at the music CD with, say, Rhythmbox and see the song/artist information but I believe it is sourcing this data off the web and not the CD. Is there a way to capture this information off the CD itself or do I know if it is even present? Looking at the 'properties' of the individual CD music files shows nothing under the 'General' information. Also the songs on the CD are simply listed as Track 1.wav, etc; no song titles. This all means that I have to manually rename these songs on my hard drive and my USB memory stick that I use on my stereo network receiver. I am using FLAC, in Terminal mode, to convert the .wav files for more efficient storage.This is also cumbersome but I want to ensure music quality/sampling rate is maintained for playback on my stereo. Any suggestions?

What are some CD ripping programs for Ubuntu? Can you list the Pros? What are the Cons? For each program there should be a screenshot, sources to install, and instructions to install and use.


A birthday is the day of your birth, much like graduation day and wedding day.  Why is birthday one word?

Examples:   Anyone Anything Anytime Anywhere Everyone Everything  Every time Everywhere No one Nothing No time Nowhere Someone Something Sometime Somewhere   Why is there a discrepancy? Is there any rule for determining when to use a single word vs. two words?


Can somebody explain me what is "Install it from Software Center", and "install from a command line" please?. I was using another OS and only two days on Ubuntu.Please help me.

Hi I'm new to ubuntu world. I have few questions about the software installation in ubuntu:   What's the difference between installing a software in ubuntu software center and command line? Why some software I installed with command line can't be searched in software center (press the window key)? What are the correct commands to install a software from command line so that I can search them? I backed and restored up my system once but some commands worked before (like "subl") don't work after restoring the system.   I think these questions are about $PATH somehow but I can't find some material about this. Any extra material would be appreciated. :)


I checked this on a graphing calculator and noticed there are two solutions for this. How do I find them? Can they be found without the help of a calculator? They were some very arbitrary values, so this there some sort, patter (if that’s the right word to describe this), present in this?

There is an unique solution with $x$ being approximately $0.739085$. But is there also a closed form solution?


We have three computers with Ubuntu connected to a LAN network. Each computer has the software each user installs, and updates are done when the users want to update. These computers share among them a hard disk of several TB.  We would like our computers to have the same software, and to be updated all at the same time. Moreover, we would like each user to know the available resources that there are in each computer. This way they might launch a process in a computer or in another depending on the available resources.  Do you know a way to do it? What do you recommend?  Thanks a lot.

Recently I got in charge of managing 2 computer labs (currently 35 workstations, could double in a month or two) in university with total control over software stack as long as I install a bunch of commonly used scientific software (Mathematica and friends).  I plan to use Ubuntu for various reasons.   Installing Ubuntu and managing updates etc by hand is certainly an option, But I want to know if there is a more efficient way to do this stuff in and a more "Don't Repeat Yourself" manner?  Tasks   Ubuntu installation Installation (duplication) of same software stack and configuration over each workstation Keeping them updated


Is choice required to guarantee that $\mathbb R^2 := \mathbb R \times \mathbb R$ – or $\mathbb R^n := \displaystyle\prod_{k=1}^n \mathbb R$ in general – isn't the empty set $\varnothing$? If not, what's an example of a Cartesian product of two non-empty sets not guaranteed to be non-empty (without choice)?

Can anyone explain how we choose one sock from each of finitely many pairs without the axiom of choice?  I mean : To choose one sock from each of infinitely many pairs of socks requires the Axiom of Choice, but for shoes the Axiom is not needed.  The idea is that the two socks in a pair are identical in appearance, and so we must make an arbitrary choice if we wish to choose one of them. For shoes, we can use an explicit algorithm -- e.g., "always choose the left shoe." Why does Russell's statement mention infinitely many pairs? Well, if we only have finitely many pairs of socks, then AC is not needed -- we can choose one member of each pair using the definition of "nonempty," and we can repeat an operation finitely many times using the rules of formal logic (not discussed here).


Where do I find Mega Stones? I have already upgraded my ring, yet nothing happened afterwards

I upgraded my Mega Ring and have been looking for Mega Stones, and I found . However, the Mega Stone isn't in the place it's supposed to be, and I'm sure the location is right. Why isn't my Mega Stone here?


What is the difference between {get;} and Readonly in the following C# code?  String name { get { return "Tom"; } } const String name = "Tom"; readonly String name = "Tom";   please explain with simple problem or any reference.

What is the difference between const and readonly in C#?   When would you use one over the other?


I would love a clear and simple rule of thumb about using fonts for a commercial purpose.   Can I use pre installed fonts on my Mac like Arial for body copy. Do you need to buy the font in every instance?  I have a creative cloud subscription so I have read I can use typekit without buying individual licenses but what about if you discontinue the subscription and the font is already being used on a product or website?  Any clarification would be great thank you  Alexis

I've noticed that most custom fonts include a license.txt file that requests some amount of money for a commercial license.  I am interested in whether it is also necessary to license OS (Mac/Windows) included fonts for commercial use.  As a side question, is font theft an issue in the industry?


I've just discovered the  questions on this meta, and wondered how and when this feature is used. For example, I just discovered that we had a  tag () on Electrical Engineering, which was variously used for source code, binary codes, color codes, and official standards.  All that, in 7 questions (which I've since edited to remove the tag).  None of these is obviously the main target of the word , so I conclude that the  tag is meaningless, and should be abolished.  Is a tag blocklist an appropriate action for this tag?  How do you decide which tags to block? Assuming that the blocklist is appropriate,how can the blocklist be created?  I don't see a way to add anything to the , and there's no mention of this privilege in the tools that I can find.

Following , I would like to know what exactly it means for a tag to be marked as blocked (formerly blacklisted) on a Stack Exchange site.  Does it mean I can't use that tag on my question? What are the reasons for blocking a tag? Who can block tags? Why am I being prompted to remove a tag from a question I'm editing?


I would like to run every method annotated with @Test, across multiple classes, at the same time.  For some cases, I would like to limit this, and say that only 100 total can run at any one time.  I would like methods with @BeforeClass annotations to be run once before any Test in a class runs, and I would like @AfterClass annotations to be run once after all Tests in a class run.  I would like System.out, System.err, and Exceptions to be appropriately buffered/captured rather than written out, so that they don't interleave, and I can read the final output and understand what happened.  Does this exist?  I have a large number of independent test cases, and my application is (I believe) threadsafe.  None of these tests have dependencies out of the JVM, and I want to finish them as quickly as possible, given my hardware.  If this doesn't exist, is there a concrete reason why not?  How much time is lost by junit users worldwide because this isn't easy?  Can I build it into Junit?  In my mind, this should be as simple as a single flag, and it "just works".

I'm using JUnit 4.4 and Maven and I have a large number of long-running integration tests.  When it comes to parallelizing test suites there are a few solutions that allow me to run each test method in a single test-class in parallel. But all of these require that I change the tests in one way or another.  I really think it would be a much cleaner solution to run X different test classes in X threads in parallel. I have hundreds of tests so I don't really care about threading individual test-classes.  Is there any way to do this?


The title says it all but for some context:   In robotics the Jacobian maps a robot's joint velocities to the velocities at its end-point.   In some quadratic programming approaches (again in the robotics context) the Hessian is considered as $\mathbf{H}=J^TJ$. Note that in our field often $J\in\mathbb{R}^{m\times n}, n > m$.  My question is, under what conditions $\mathbf{H}=J^TJ$ holds or is a valid approximation. I've seen papers that say this notion isn't valid in some cases.

I met this equation frequently in Guass-Newton optimizations. But I dont understand why the left and right side of the equation can be equal.  Lets say the Jacobian is $2$ by $2$   and Hessian is $$\begin{bmatrix}\frac{\partial^2f_1}{\partial^2 x_1 } & \frac{\partial^2f_1}{\partial^2 x_2  } \\ \frac{\partial^2f_2}{\partial^2 x_1 } & \frac{\partial^2f_2}{\partial^2 x_2  }\end{bmatrix}$$   But the right hand side of the equation is  $$J^TJ =\begin{bmatrix} \left( \frac{\partial f_1}{\partial x_1} \right)^2 + \left( \frac{\partial f_2}{\partial x_1} \right)^2  &  \frac{\partial f_1}{\partial x_1}\frac{\partial f_1}{\partial x_2} +\frac{\partial f_2}{\partial x_1}\frac{\partial f_2}{\partial x_1}\\ \frac{\partial f_1}{\partial x_1}\frac{\partial f_1}{\partial x_2} +\frac{\partial f_2}{\partial x_1}\frac{\partial f_2}{\partial x_1} &\left( \frac{\partial f_1}{\partial x_2} \right)^2 + \left( \frac{\partial f_2}{\partial x_2} \right)^2\end{bmatrix} $$  Why can these two be equal as presented in papers?


I'm trying to make a 2d array in c++ which displays next digits of pi decimals.  but a line:   table[row][element] = (int)pi[counter] - 48;   I get this error: 0xC0000005 telling me that I violated access rules while reading in a location: 0x0000000000000000  How can I solve this error? I'm beginner at C++  vector<vector<int> > table; long int couner = 0;   const string pi = "3141592653589793238462643";     for (int row = 0; row < n; row++) {         for (int element = 0; element < n; element++) {             table[row][element] = (int)pi[counter] - 48;             counter += 1;         }     }

I know that the compiler will sometimes initialize memory with certain patterns such as 0xCD and 0xDD.  What I want to know is when and why this happens.  When  Is this specific to the compiler used?  Do malloc/new and free/delete work in the same way with regard to this?  Is it platform specific?  Will it occur on other operating systems, such as Linux or VxWorks?  Why  My understanding is this only occurs in Win32 debug configuration, and it is used to detect memory overruns and to help the compiler catch exceptions.  Can you give any practical examples as to how this initialization is useful?  I remember reading something (maybe in Code Complete 2) saying that it is good to initialize memory to a known pattern when allocating it, and certain patterns will trigger interrupts in Win32 which will result in exceptions showing in the debugger.  How portable is this?


EDIT: This does not really seem a duplicate to me since  in broader in scope (how to use it). Anyways, the answer to my question does turn out to be there in paercebal's  and is namespace composition. Another related source in SO is this other .    I've been trying to modularize my code using namespaces. Anon's  to a question on nested namespaces got me wondering whether they should be used for design instead of simply avoiding name clashes.  I feel like namespaces (occasionally nested ones) are useful to organize the code, but sure things like world::europe::spain::madrid become cumbersome to use. Therefore, from an API point of view, having most code in the same namespace (just like the std library) works best.  My question is then two fold:   Should namespaces be used to organize code or simply to avoid name clashes? and if so How to have a "complex" namespace structure while keeping the API clean?   Regarding question 2, I've been using the following strategy:  (1) having some code with its own namespace  //mathlib.h  namespace mathlib {     int sum( int a, int b ) {         return a + b;     } }   (2) and bring it into another namespace  //otherlib.h  #include <iostream> #include "mathlib.h"  namespace otherlib {     using namespace mathlib; // lookup stuff inside mathlib      void print(int n) {         std::cout << "the int is " << n << "!";     } }   (3) So I can actually call sum as it were under the otherlib namespace.  #include "otherlib.h"  int main(){     auto myint = otherlib::sum(1, 2);     otherlib::print(myint);     return 0; }

I come from a Java background, where packages are used, not namespaces. I'm used to putting classes that work together to form a complete object into packages, and then reusing them later from that package. But now I'm working in C++.  How do you use namespaces in C++? Do you create a single namespace for the entire application, or do you create namespaces for the major components? If so, how do you create objects from classes in other namespaces?


I'm an Indian National staying in Germany on a Blue card. Now I'm about to resign from my current job and move to the US for a new one.   My question is, for how long will my blue card be valid? Can I use it for visiting the EU as a tourist at an later point?

I am Australian and as such from a non-EU country and hold a German "Blue Card EU" which is tied to a job I had in Germany. I worked there for 1 year but stopped working there last week.  I am now in the process of applying for a Swiss working permit and I intend to move there and begin working there when that is finished. I was told that it could take more than 3 months though to get the working permit, which is kind of worrying because I am only allowed 90 visa-free days in the Schengen zone.  Therefore my question is: how long can I stay in Germany now that I have quit the job for which I had my Blue Card? Citizens of my country get 90 visa free days, so there's that, but do I get any "extra" time thanks to my blue card? It surely musn't expire as soon as I quit my job, right?


we have for example this file  cat exam.txt  I am expert linux man what we can do for out country I love redhat machine "propertie" centos less then redhat fedore what my name is moon yea   we want to add the content of any file as file.txt after properties line  cat file.txt  324325 5326436 3245235 646346 545 643 6436 63525 664 46454   so I try the following:  a=` cat file `  sed -i '/propertie/a  `echo "$a"` ' exam.txt   but not works  any suggestion with sed/awk/perl one liner in order to add content of file after  certain string?  expected output  I am expert linux man what we can do for out country I love redhat machine "propertie"     324325     5326436     3245235     646346     545     643     6436     63525     664     46454 centos less then redhat fedore what my name is moon yea

I have two different files:  File1  /home/user1/   /home/user2/bin   /home/user1/a/b/c   File2  <TEXT1> <TEXT2>   I want to replace the <TEXT1> of File2 with the contents of File1 using sed. I tried this command, but not getting proper output:  cat File2|sed "s/<TEXT1>/$(cat File1|sed 's/\//\\\//g'|sed 's/$/\\n/g'|tr -d "\n")/g"   You can use other tools also to solve this problem.


Assuming the theories that the Gluon field and the Higgs field are both responsible for particles gaining mass, how would both exist simultaneously in the same world? How would they interact with each other? And why isn't one field alone responsible for particles gaining mass?  Edit: Found this link to a 2013 question that appears to answer this one...

The video  argues that almost all the mass that we are made of doesn't come interaction with the , but rather that most of a nucleus's mass comes from the space between quarks (the ).  If the video is correct, then there really needs to be an easy-to-understand explanation for mass because science popularizers make us laypeople think that the Higgs mechanism is responsible for all the mass in the atoms and that would be of course very misleading.


I have a function (called data_type) that returns the type of the object in the form <class 'int'>. I need the output of this function to check whether the object is int or float or str. The problem is that I cannot use the output if data_type in ininstance as I need to pass it the original object rather its type. What I am saying is that I cannot use the following -   isinstance(data_type(some_variable), float)   as it translates to  isinstance(<class 'float'>, float)   and even though the object is of float type, it will return False because the type of class 'float'> is type itself.   I understand that some will suggest me to change the way I approaching this but and I agree this is not the way to go about it but I can't change the output type of the data_type function.  I looked in to the  module where they have things like types.StringType but unfortunately, that's only for python2. That functionality isn't available for python3 (which is what I am currently using and can't change).  So the question is how do I use the return of the type function to check if an object is str/float/int.   I need to select out objects which are of class str and so as a hack I am using   if str(self.dtypes[each_col]) == "<class 'str'>": ...  But I am not comfortable doing that. Is there any other way through which I can do this?

What is the best way to check whether a given object is of a given type? How about checking whether the object inherits from a given type?  Let's say I have an object o. How do I check whether it's a str?


Here is the line of code which help to find assembly for required culture:  Assembly.GetExecutingAssembly().GetSatelliteAssembly(new CultureInfo(cultureCode))   But how to find languages for which satellite assemblies exist for application, lets say if there are 3 language support for which 3 different folder created, now I want those folders and languages supported in it. I use this in drop down from where user can select language and drop down values should be dynamically loaded as per supported satellite assemblies.

I'm designing a multilingual application using .resx files.  I have a few files like GlobalStrings.resx, GlobalStrings.es.resx, GlobalStrings.en.resx, etc. When I want to use this, I just need to set Thread.CurrentThread.CurrentCulture.  The problem: I have a combobox with all the available languages, but I'm loading this manually:  comboLanguage.Items.Add(CultureInfo.GetCultureInfo("en")); comboLanguage.Items.Add(CultureInfo.GetCultureInfo("es"));   I've tried with  cmbLanguage.Items.AddRange(CultureInfo.GetCultures(CultureTypes.UserCustomCulture));   without any success. Also tried with all the elements in CultureTypes, but I'm only getting a big list with a lot more languages that I'm not using, or an empty list.  Is there any way to get only the supported languages?


This is my first question on this website, so I hope I don't embarrass myself. While I was helping my friend study for the GRE exam, I noticed that a lot of the vocabulary lists contained two word expressions, which I had never seen before. They were used to describe such situations as confusion, a mixture and even certain adjectives. I remember only a few right now, these being:  helter-skelter hodge podge hoi polloi nitty-gritty pell-mell  The way these were used in sentences simply excited me, due to the sheer beauty and the lack of their usage in common written expositions, these seem like a mystery to me, as they have evolved from many, many languages, with some having ambiguous origins, the contexts they are used in seem clear, and they seem to work so remarkably well whenever employed, and they just seem to add beauty to an otherwise ordinary sentence. I was therefore wondering if someone here could please provide a reference for a list of these expressions and their meanings and context. Specifically, a list where the above mentioned expressions, with more of similar appearance abound. I am sorry I don't even know the name of this type of expression, but again I was mesmerized by their beauty, elegance and mysterious origins.

Some English words only differ in their vowels: crisscross, dillydally, riffraff, etc. Is there a name for them?


A tree has $n_2$ vertices have degree 2, $n_3$ vertices have degree 3, ..., $n_k$ vertices have degree k. How many vertices in this tree have degree 1.

I have to prove the following claim, given the tree $T=(V,E)$, $|V|=n\geq2$:  $$|V_1| = 2 + \sum (j-2)|V_j|$$  where the sum is from $j=3$ up to the highest degree, and $$V_i = \{ x \in V \mid \deg(x) = i\}.$$  This was a bonus question given by my professor. We were sitting on this question for hours and have no idea how to prove it.  Can someone help out with a hint?  Thanks!


Is there a word to describe someone who overreacts to the judgement of others, i.e., they over-correct their behavior or are overly fearful of the judgement of others?

I'm looking for a word to describe someone who is sensitive to the point that other have to tiptoe around her. In other words, someone who can't handle routine jokes, normal criticism, or a comment that can possibly be interpreted in a negative way, even when it wasn't meant like that.


Let $x_1,x_2 \in \mathbb R$ and let $(a_0, \dots, a_k), (b_0, \dots, b_k)$ be $(k+1)$-tuples of real numbers. Show that there is a unique polynomial of degree at most $2k+1$ such that   $$p^{[j]}(x_1)=a_j \text{ and } p^{[j]}(x_2)=b_j \text{ for } j=0,\dots, k.$$      [Consider the polynomials $(x-x_1)^k (x-x_2)^{k+1}$, $(x-x_1)^{k+1}(x-x_2)^k$ and argue by induction.]   Any help with this exercise?

Let $x_1, x_2 \in \mathbb R$ and let $(a_0, a_1, \dots, a_n), (b_0, b_1, \dots, b_n)$ be $(n+1)$-tuples of real numbers. Show that there is a unique polynomial of degree at most $2n+1$ such that $$q^{[k]}(x_1)=a_k,$$$$q^{[k]}(x_2)=b_k$$ for $k=0, \dots, n$.   Any hints on how to get started with this exercise?


The wireless used to be just fine now is dead slow.  How i should troubleshoot this issue any idea? Thank you.

I have to reset my internet connection often to get it to work.  When it does work, it's definitely slower than when I'm on my Windows installation.  My computer uses an RTL8188CE wireless card from Realtek.  I'm running the 64-bit version of Ubuntu 12.10.  Power management is not on.  I've read on other sites that some people fixed the issue pertaining to this wireless card by downloading and installing the drivers from the Realtek site, but it seems as if that only helped people with 32-bit installations.  Anyone have any luck with this specific wireless card?


I am trying to compare two strings with pdf@strcmp but I get the error:  ! Undefined control sequence. <argument> \pdf              @strcmp{abc}{abc} l.6     \section{\pdf@strcmp{abc}{abc}}   Here is what I am trying to run:  \documentclass{report} \usepackage{pdftexcmds}  \begin{document}     \section{\pdf@strcmp{abc}{abc}} \end{document}   I was expecting to see something like 0 being output. From what I understand the strcmp returns 0 if the strings are equal, -1 if A < B and 1 otherwise. I've installed the oberdiek package so I believe I have the dependencies I need.  This seems simple but I must be missing something obvious so, how do I make this comparison?

Many LaTeX “hacks” begin with \makeatletter and end with \makeatother. What do these commands do?