Can anyone provide a concise distinction between anonymous method and lambda expressions?  Usage of anonymous method:  private void DoSomeWork() {     if (textBox1.InvokeRequired)     {         //textBox1.Invoke((Action)(() => textBox1.Text = "test"));         textBox1.Invoke((Action)delegate { textBox1.Text = "test"; });     } }   Is it only a normal lambda expression being cast to a strongly typed delegate or there is more of it undercover.  I'm well aware that a strongly typed delegate like follow  UpdateTextDelegate mydelegate = new UpdateTextDelegate(MethodName)   suffice as a parameter of type System.Delegate, but the idea of anonymous method is rather new to me.

What is the difference between anonymous methods of C# 2.0 and lambda expressions of C# 3.0.?


Does every line in a projective plane of $7$ points have exactly three points lying on them? This was my attempt, it seems to me that this fact is true. Could anyone verify it or provide any other proof/counterexample(if there are any) ? Call that projective plane $P$. First of all a line in $P$ cannot have all the seven 7 points lying on them as that would contradict the axiom that "there exists three non-collinear points in every projective plane". A line in $P$ can also not contain $6$ points, as if it were, then the the other point call it $X$ would be arbitary and any line joining $X$ and one of the points among those $6$ will not contain atleast three points because there are only 7 points in $P$ and thus would contradict the axiom that a line in a projective plane conists of atleast three points. With a similar reasoning we can show that a line in $P$ cannot contain $4,5$ points, thus there are always $3$ as there cannot be less than $3$ points lying on a line in a projective plane. Thanks!

I've been reading some proofs regarding finite projective planes of order n, and often they start out by assuming that each line contains n+1 points. Is this a fact that follows from the axioms for finite projective planes? Or does this relate to the order of the finite field being projected? (for example in the Fano plane, does the fact that each line contains 3 points follow from the fact that there are 3 elements {0,1,2} in Z_2?) I haven't been able to find a clear explanation of this (clearly I do not yet have a solid understanding of how such planes are constructed). If someone could enlighten me that would be excellent.


I hope you are doing well and are healthy.  I'm struggling with the wifi connection on my Lubuntu 19.04/Windows 10 dual boot on a dell laptop. The only things I changed were in the BIOS  Go from RAID to AHCI Disabled secure boot   The wifi worked after the installation for a couple of days and then for no obvious reasons I'm not seeing any wifi connections any more on the bottom right and the symbol itself also disappeared. On the Windows 10 partion everything works fine.  I have literally no idea about what do about it. I tried a couple of things but non of them work. I can connect via ethernet though. I found a script which gathers all kind of network related information. Please see the following attached log file. It was marked as spam, therefor I couldn't write it here.    Maybe this helps , but I how do I find out which wifi driver I need?  I really hope any of you has an idea about what is wrong. I'm very gratefull for any clue.  Feel free ask to my anything because I tried my best to fix the issue but I'm lost.  Thanks, René

I have a Dell Vostro 5490 with Ubuntu 18.04 installed in dual boot with Windows 10. I currently have no WIFI. I have tried to update and upgrade my packages, and I have also followed  guide, but without success. Except for the things mentioned, my Ubuntu is completely stock, I have not done any other modifications. Please help me out with this issue, any help would be greatly appreciated!  This is the output from the command lspci -knn | grep Net -A3; rfkill list:  00:14.3 Network controller [0280]: Intel Corporation Device [8086:02f0]     Subsystem: Intel Corporation Device [8086:42a4]     Kernel driver in use: iwlwifi     Kernel modules: iwlwifi 0: hci0: Bluetooth     Soft blocked: yes     Hard blocked: no   Here is a paste of the output from the command dmesg | grep iwl:


Assume that a variable $x$ is strictly postive. I m looking for resources about polynomials with real degree, i.e: $a_1x^{r_1}+...+a_px^{r_p}$, where $a_i,r_i$ are real numbers. Is there any name for this ? Or better yet for integrals of such, i.e. $\int a(s)x^s ds$ with a(s) being some function

Are there some books or articles regarding "polynomials" with non-integer (real) exponents, i.e., $$f(x)=a_1x^{e_1}+a_2x^{e_2}+\dots+a_nx^{e_n},$$ where $e_1,e_2,\dots$ are any real numbers (and $x$ being also real)?  I am mostly interested in theorems regarding the location of the roots, number of the roots, bounds, etc., of such "polynomials". Thanks.


There seem to be plenty of resources for how to do it (even on this website), but I'm struggling with the process.   Can someone provide a link to an example pdf with the working animations in it? The only I see have buttons and are interactive (but aren't working on my machine anyway)-- what I would like is even simpler, just a looping gif file that never stops (I'm trying to show the evolution of a system, against certain parameters and time).   Thanks for any examples.

I am trying to use movie15 to embed vector animations in my presentation. The trouble is that embedded SWF files refuse to display on Acrobat Reader X sometimes with a "This Media requires an additional player" message. Eg. this  doesn't work. Animated GIFs won't display either, with no error message.   Maybe this is an Acrobat issue but I tried the flashmovie package with the same SWF files and that does work (but only with the embedded player option so no controls are visible). But flashmovie is supposedly unstable with beamer so I was wondering if someone had run into the same problem with movie15.  I am using Windows 7, Acrobat 10.1.2 and MiKTeX.


Prove that if $\{a_n\}$ converges to $a$, that $\{(a_n)^2\}$ converges to $a^2$ by definition.  Pf.  Suppose $\{a_n\}$ converges to $a$.  This means: $$\forall \epsilon >0, \exists N>0, \text{s.t, if} \text{  }n>N, |a_n-a|< \epsilon$$  I want to show that: $$\forall \epsilon >0, \exists N>0, \text{s.t, if} \text{  }n>N, |a_n^2-a^2|< \epsilon$$  How do I use the given info? I don't know how I can manipulate it to get $a_n^2$

I am really struggling with my proofs class, I don't really understand how to prove a statement like this, or what the epsilon is standing for..  Suppose that $(s_n)$ converges to s.  Prove that $(s_n^2)$ converges to $s^2$ directly without using the fact that $lim(s_nt_n)=st$  Suppose that $(s_n)$ converges to s. Then, since $(s_n)$ is convergent, there exists an $M_1$ such that $|S_n|<M_1$, for all $n\in \!\,\mathbb{N} \!\,$. Let $M=M_1+|S|$ (I don't completely understand this step...). Then given $ε>0$, there exists N such that n>N implies that $|s_n-s|<ε/M$. Thus for n>N, we have $|s_n^2-s^2|=|s_n-s|*|s_n+s|<(ε/M)(M)=ε$. Hence, $s_n^2$ converges to $s^2$.


Evaluate the following integral  $\int{\frac{1}{(x+a)(x+b)}}$  (this might involve partial fraction decomposition, $\int{\frac{1}{x^2+x(a+b)+ab}}$ this is what my first step was)

Evaluate the following integral.  $\int\frac1{(x+a)(x+b)}~dx$  ${a}\neq{b}$  I do not know where to being solving this integral.


I am wanting to calculate albedo from a Landsat 8 set of bands. When I use GRASS' Processing toolbox i.albedo, within QGIS, the option for landsat 8 is not avaialbe, however if I use GRASS separately it is (See photos below) Also, notice that the newest version of GRASS has included albedo calculation for Landsat 8 from the latest manual.

I have been using QGIS and Grass for ages and while I've noticed this issue before, I've not been bothered by it until now.  It is (hopefully) a bit of a noob question but when I open GRASS in the QGIS Processing toolbox, I notice that a lot of standard utilities appear to be missing (e.g. r.in.bin and others  - There are only 161 commands listed for Grass 6.4.3 and this figure should be much higher).    I am not talking about add-on plugins but standard parts of the GRASS toolset (according to the Grass documentation).  Looking in the Grass bin folder, however, I can see the are there.  It is not that the bin folder is not recognized as I can see many of the other utilities there in Processing.  I have tried updating to the latest version of QGIS (2.18) with OsGeo4W and re-installing both Grass 6.4.3 and 7.2.  I have checked the paths in Processing-options and all looks fine (in as much as the paths point to the top-level directory in each case as they always have).  How can I make the missing ones appear in the Processing toolbox?


Why we can not call this function Base::P(int)?  class Base {    protected:     string s = "Base"; public:     void P(int a){ cout << "Base" << endl; } }; class Derived : public Base  public:     using Base::s;       void P(){ cout << "Derived" << endl; } };  int main() {     Derived a;     a.P(2);   // Error, Why we can not use Base::P(int)? }   Why we can not use Base::P(int)?

I have a function with the same name, but with different signature in a base and derived classes. When I am trying to use the base class's function in another class that inherits from the derived, I receive an error. See the following code:  class A {     public:     void foo(string s){}; };  class B : public A {     public:     int foo(int i){}; };  class C : public B {     public:     void bar()     {         string s;         foo(s);     } };   I receive the following error from the gcc compiler:  In member function `void C::bar()': no matching function for call to `C::foo(std::string&)' candidates are: int B::foo(int)   If I remove int foo(int i){}; from class B, or if I rename it from foo1, everything works fine.   What's the problem with this?


I needed a character that looks like a d with a bar through it, so I found this snippet of code.  \newcommand{\dbar}{{\mathchar'26\mkern-12mu d}}   This creates the right character, but it doesn't have normal spacing for a math symbol, so I end up with something like the picture below, where I've included a regular $\hat{d}$ for comparison to what it should look like. Any advice on how to fix this?

In math mode one can do $\hbar$, which produces an h with a little line through the top of it. I want to do the same thing, except with the letter d instead. Is there a generalization of $\hbar$ that works for other letters besides just h?


I have two files:  k.txt:  3 5 7 9 19 20    h.txt:  000010 100001 111001   if I just use cat, there is no newline. I need a command which would provide a file which looks like this:  3 5 7 9 19 20  000010 100001 111001


As I know  == is used to compare references. .equals() is used to compare content.  There is a string pool is available in java. For example I created a string as follows  String s ="ABC"; then address for this is suppose 12345  When I use same string i.e "ABC" same string will share in both places. That means addresses for both strings are same.  == is for compare references .In this case address for both strings are same.Then why I need to go for equals() method.Please correct me if I am wrong.  public class StringComparison {  public static void main(String[] args) {     String s1 ="test";     String s2 = "test";      if(s1 == s2)         System.out.println("BOTH ARE  == ");     else         System.out.println("BOTH ARE != ");       String s3 = new String("test");     String s4 = new String("test");      if(s3 == s4)         System.out.println("BOTH ARE  == ");     else         System.out.println("BOTH ARE != ");    } }  OUTPUT: BOTH ARE  ==  BOTH ARE !=    But the reference link says new String("test") == new String("test") ==> false

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 working with OpenJPA 2.2.1 and would like to do the following:  1) Load an entity 2) Change the entity 3) Check the changes done before saving the entity  What I've done:  1) Load the entity via      EntityManager.find(MyObject.class, id);   2) Ok, pretty clear, I think, something like      MyObject obj = EntityManager.find(MyObject.class, id);     obj.setName("New name");   3) Tried to evict the object from the PersistenceContext and loading it again from the database via:      EntityManager.evict(MyObject.class, id);     EntityManager.find(MyObject.class, id);   The entity returned by the find() call in 3) is always equal (equal ID) to the entity found in 1)  I thought I could remove the entity from the PersistenceContext / cache by evict.  How can I achieve to have two different entities: a) the changed entity and  b) the original entity from the database loaded in step 3)  And: If i refresh() the entity I expect the find method to return the refreshed one. Is that correct?  I tried the @PreUpdate listeners too with the same result so I think there must be something I have not understood regarding JPA PersistenceContext or Java references...  I hope I provided enough information! Thanks in advance!

I want to compare the current value of an in-memory Hibernate entity with the value in the database:  HibernateSession sess = HibernateSessionFactory.getSession(); MyEntity newEntity = (MyEntity)sess.load(MyEntity.class, id); newEntity.setProperty("new value"); MyEntity oldEntity = (MyEntity)sess.load(MyEntity.class, id); // CODEBLOCK#1 evaluate differences between newEntity and oldEntity sess.update(newEntity);       In CODEBLOCK#1 I get that newEntity.getProperty()="new value" AND oldEntity.getProperty()="new value" (while I expected oldEntity.getProperty()="old value", of course). In fact the two objects are exactly the same in memory.  I messed around with HibernateSessionFactory.getSession().evict(newEntity) and attempted to set oldEntity=null to get rid of it (I need it only for the comparison):  HibernateSession sess = HibernateSessionFactory.getSession(); MyEntity newEntity = (MyEntity)sess.load(MyEntity.class, id); newEntity.setProperty("new value"); HibernateSessionFactory.getSession().evict(newEntity); MyEntity oldEntity = (MyEntity)sess.load(MyEntity.class, id); // CODEBLOCK#1 evaluate differences between newEntity and oldEntity oldEntity = null; sess.update(newEntity);   and now the two entities are distinct, but of course I get the dreaded org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session.  Any idea?  EDIT: I tried the double session strategy; I modified my HibernateSessionFactory to implement a map of session and then...  Session session1 = HibernateSessionFactory.getSession(SessionKeys.DEFAULT); Session session2 = HibernateSessionFactory.getSession(SessionKeys.ALTERNATE); Entity newEntity = (Entity)entity; newEntity.setNote("edited note"); Entity oldEntity = (Entity)session1.load(Entity.class, id);  System.out.println("NEW:" + newEntity.getNote()); System.out.println("OLD: " + oldEntity.getNote()); // HANGS HERE!!!  HibernateSessionFactory.closeSession(SessionKeys.ALTERNATE);   My unit test hangs while attempting to print the oldEntity note... :-(


How to prove that UFD implies normal? or is there is a reference containing this proof? a ring $R$ is a normal ring if $R$ is an integral domain that is integrally closed in $\operatorname{frac}(R).$ And $R$ is integrally closed in a commutative ring $S$ iff the integral closure of $R$ in $S$ (int($R$)) equals $R$. And int($R$) consists of all $x \in S$ that is integral over R. And note that an element is integral over $R$ if there exists a monic polynomial $f(x) \in R[x]$ such that $f(x) = 0.$

Let $A$ be a UFD, $K$ its field of fractions, and $f$ an element of $A[T]$ a monic polynomial.  I'm trying to prove that if $f$ has a root $\alpha \in K$, then in fact $\alpha \in A$.  I'm trying to exploit the fact of something about irreducibility, will it help? I havent done anything with splitting fields, but this is something i can look for.


Describe all groups $G$ which contain no proper subgroup. I did not understand the meaning of the question actually. Any help would be appreciable, thank.

This is something I'm supposed to be able to prove for an upcoming test, but I can't find anything to help me prove this in my notes or the chapter, which is on cosets and Lagrange's theorem. If all I start with is the group having no proper subsets, then that means any subset is the whole group. By Lagrange's theorem, that means the index is $1$, but that doesn't get me anywhere. Where do I start?


I'm trying to find the natural numbers $n$ in which $n^2$ divides $584$ ?  i tried all the ways i know but i get stuck.

Well, I've confused when trying to solve this equation can anybody help me :  $n^2 \equiv 0 \pmod{584}$  I tried to factorize the $584$ i got $584=2^3\times73$.  so $n^2$ has to be divisible by $2^3$ and $73$ in this same time.  here i get stuck.


I learned how to view the configuration files for a package that's already installed from reading:    Using dnsmasq as an example, I can view the files and configuration files for that package after it's installed using these two commands:  cat /var/lib/dpkg/info/dnsmasq.conffiles dpkg -L dnsmasq   I know I can search for the existence of the package and get relevant meta data about the package using these commands  dpkg --list | grep dnsmasq apt-cache search dnsmasq apt-cache show dnsmasq   But, I'd like to know the configuration files for the package before installing it.  How do I list configuration files for a package before installing the package?

apt-cache search returns list of available packages. In my case I would like to look at  the list of files that would be installed on my PC in case I install the package usb-creator-gtk.  Something like dpkg-query -L does for an already installed package.   Thanks for help.


I want to comment out a whole section in order to save the text but not render it in the PDF. Is this possible?

To "comment out" a line, I need to insert a % at the beginning of the line (so that the line will not be compiled). Is there a way to comment out a large section without having to manually place % in front of each line?


I am trying to solve the following exercise:  Let $\mathbb{Z}\omega_1+\mathbb{Z}\omega_2$ be a lattice in $\mathbb{C}$ and let $\theta$ be an entire function such that there exist $a_1,a_2\in\mathbb{C}$ such that $\theta\left(z+\omega_j\right)=a_j\theta\left(z\right)$ for all $z\in\mathbb{C}$ and $j\in\left\{1,2\right\}$. Prove that $\theta\left(z\right)=ae^{bz}$ for some $a,b\in\mathbb{C}$.  So, if $\theta=0$, there is nothing to prove. Assume $\theta\neq 0$. Observe that $a_1\neq0\neq a_2$ because $\theta\left(z\right)=a_j\theta\left(z-\omega_j\right)$ and $\theta\neq 0$. If $a_1=a_2=1$ then $\theta$ is an entire elliptic function and therefore it is constant, and this proves what we want (take $b=0$). Assume that at least one $a_j$ is not equal to $1$. It follows that $\theta\neq 0$ cannot be constant, since otherwise $a_1=a_2=1$. Since $\theta'$ satisfies the same conditions as $\theta$ does, assume we could prove what we want for $\theta'$. If $\theta'=ae^{bz}$, we cannot have $b\neq 0$ since otherwise $\theta=az+c$ for some $c\in\mathbb{C}$, which shows that $a\neq 0$ (because $\theta$ is not constant) and then, using the hypothesis on $\theta$ and comparing coefficients, we would obtain $a=a_ja$, which implies $a_1=a_2=1$, a contradiction. So $\theta'=ae^{bz}$ where $b\neq 0$ (and $a\neq 0$ because $\theta$ is not constant), and therefore $\theta=\frac{1}{b}\theta'+d$ for some $d\in\mathbb{C}$. Using that both $\theta$ and $\theta'$ satisfy the conditions of the statement, one easily obtains $d=a_jd$, so $d=0$ because at least one $a_j$ is not equal to $1$. So $\theta=\frac{1}{b}ae^{bz}$ also has the desired form. The above paragraph shows that if we prove the problem for $\theta'$ then it is also solved for $\theta$ (assuming that $\theta\neq 0$ and at least one $a_j$ is not equal to $1$). I do not know whether it helps. Another idea I had was the following: keep assuming $\theta\neq 0$ and at least one $a_j$ is not equal to $1$ (the other cases were already handled) and consider the meromorphic function $\psi=\frac{\theta'}{\theta}$. Since both $\theta$ and $\theta'$ satisfy the conditions of the statement and $a_1\neq 0\neq a_2$ (because $\theta\neq 0$), one easily shows that $\psi$ is an elliptic function. So if we could show that it is entire, we would be done: it would be constant and that would give what we want. But of course, $\psi$ may not be holomorphic: $\theta$ may have some zeros. I thought of using the above paragraph and take enough derivatives of $\theta$ to get rid of the possible zeros, but of course it does not work because taking derivatives may introduce new zeros. How would you solve this problem?

Let $\lambda_1$ and $\lambda_2$ be complex numbers with nonreal ratio. Let $f(z)$ be an entire function and assume there are constants $a$ and $b$ such that $$f(z+\lambda_1)=af(z) \;\;\;\;,\;\;\;\; f(z+\lambda_2)=bf(z)  $$ for all $z$. Prove that $f(z)=Ae^{Bz}$ , where $A$ and $B$ are constants.   I think the idea is to build a doubly periodic entire function, but I'm not sure if it is $\displaystyle \frac{f(z)}{e^{Bz}}$.    This is exercise 10 from chapter 1 of the book "Modular forms and Dirichlet series" by Tom Apostol.  Any help would be appreciated.


I do not understand how $$\lim_{x \to 0} \frac{\sin x}{x} = 1$$ As if $$ x = 0, \frac{\sin (0)}{0} = \frac {0}{0} $$  So if someone could explain this I would appreciate it! Thanks!

How can one prove the statement $$\lim_{x\to 0}\frac{\sin x}x=1$$ without using the Taylor series of $\sin$, $\cos$ and $\tan$? Best would be a geometrical solution.  This is homework. In my math class, we are about to prove that $\sin$ is continuous. We found out, that proving the above statement is enough for proving the continuity of $\sin$, but I can't find out how. Any help is appreciated.


I do not know how to approach this integration problem. $$ \int_{-1}^{1} \frac{1}{(e^x+1)(x^2+1)} $$  I tried some trigonometric change of variable and also tried to break it into two fractions but I failed!


As we know that it was Borden who sends Angier to Tesla when he asks the trick behind his magic.  So, How did Borden knew that Tesla's machine could create a replica?  Did he use Tesla's machine to create a replica(Fallon) or were they real time twin brothers?

Towards the end of , it's revealed that Borden accomplishes his Transported Man trick by using his twin brother, Fallon, as a double. It then becomes clear that he has been doing this in his personal life as well as on stage - each brother leads 'half a life', sometimes appearing as Borden and sometimes as Fallon. This is how he completes the illusion: one Borden goes into the first door, the other Borden emerges from the second door a moment later. Angier doesn't know how Borden does the trick, and doesn't believe Borden uses a double despite being told as much by Cutter. He follows what he believes to be a clue in Borden's notebook and travels to Colorado to meet Nikola Tesla, who Angier believes can build a machine that can help him perform the trick. Angier believes that Tesla built a similar machine for Borden. However, the final pages of the notebook reveal that Tesla was merely a red herring, designed to get Angier out of Borden's way for a long time. Tesla, it turns out, had never built such a machine before. At this point, Tesla agrees to build Angier's machine anyway. Instead of building a machine that transports matter, he builds one that duplicates it. Angier uses this machine in his act, but in order to avoid having to deal with multiple clones (the "prestige materials"), one of them must die as part of the act. This all makes sense, so far, but I find it hard to believe that Borden's use of the word 'Tesla' as the key to his cipher is random. It's too coincidental that he sends Angier on a wild goose chase, but Angier returns with a working machine. A film that is otherwise so tightly plotted shouldn't rely on coincidence to move the narrative forward, so there must be something else going on. Is it possible that Borden cloned himself using Tesla's machine?


How can I find out what the element is that a <script> sits in? As an example, let's take this  <div>  <script type="text/javascript">   var time = new Date(), hrs = time.getHours(), min = time.getMinutes();   document.write('It is '+hrs+":"+(min<10?'0':'')+min);  </script> </div>   Then if I want to change this to something more modern, how can I find out what element we're in? So I want to write, for instance in jQuery  $(thisdiv).html('It is '+hrs+":"+(min<10?'0':'')+min);   but how do I get thisdiv? Yes, I know, I can put an ID on it, but I have the feeling that wouldn't be necessary. The browser knows where we are, otherwise it couldn't even do the document.write!    So, suggestions? I searched, but couldn't find it. Is it so simple that I'm overlooking the obvious?

How can I reference the script element that loaded the javascript that is currently running?  Here's the situation. I have a "master" script being loaded high in the page, first thing under the HEAD tag.  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <script type="text/javascript" src="scripts.js"></script>   There is a script in "scripts.js" which needs to be able to do on-demand loading of other scripts. The normal method doesn't quite work for me because I need to add new scripts without referencing the HEAD tag, because the HEAD element hasn't finished rendering:  document.getElementsByTagName('head')[0].appendChild(v);   What I want to do is reference the script element that loaded the current script so that I can then append my new dynamically loaded script tags into the DOM after it.  <script type="text/javascript" src="scripts.js"></script> loaded by scripts.js--><script type="text/javascript" src="new_script1.js"></script> loaded by scripts.js --><script type="text/javascript" src="new_script2.js"></script>


The doubt arises from my understanding of Newton's second law. First I though it was just the definition of force but it actually states the relation between force, acceleration and mass (which can be verified empirically).  So, the next question was what exactly is the definition of force? I am not satisfied to just call it a push or pull. Further, could we have developed our physics without having developed the concept of force and instead representing it in terms of other fundamental quantities?  Like, I believe conservation of energy principle can be use to arrive at the same result of newton's second law without having to go through the concept of force. So, in that sense, is Newton's second law redundant?

I'm looking to get rigorous definitions on which to base the important quantities in classical mechanics.  To me a "rigorous" physical definition is an operational definition -- that is one in which we define how to measure the quantity over the course of an experiment -- or a definition in terms of other quantities which are operationally defined.  Time can be measured (at least in classical theory) arbitrarily well with clocks.  Whether or not we can actually build a clock with the necessary accuracy is not important for this definition as long as we can conceive of one being built.  Position can be measured arbitrarily well with measuring sticks.  Using these two quantities above we could conceive of strategically placing an array of measuring sticks and clocks (that is building a reference frame from them) so as to entirely measure the motion -- position, velocity, acceleration, etc as a function of time -- of any object we care to.  Now I turn my attention to the most important equation in Newtonian mechanics: $F=ma$ (or $F=\dot p$ it doesn't really matter in this case).  For this equation to make any physical sense we need to be able to measure the mass and/ or force (and/ or momentum) of an object during any experiment arbitrarily well.  How can we define force or mass (or momentum) in such a way that in the midst of some complicated motion -- possibly involving losing/gaining mass, etc -- we can still be certain that we can measure values for these quantities?  One note on this: I would prefer not to assume the equivalence principle as a way of measuring mass.  Let's just pretend that inertia mass and gravitational mass are not the same because, as far as I can tell, in classical mechanics there is no strong reason to believe the equivalence principle holds based solely on Newton's laws (and other equally important "first principles" like the conservation laws).  Of course, there's empirical evidence, but again let's just ignore this for now and see if we can find another way of measuring mass (or force or momentum or kinetic energy or any other thing which as allow us to obtain a measurement of mass indirectly).    EDIT: This will be a response to the  (admittedly a similar question) detailing why I find the answers therein unsatisfactory.  My hope is that either someone can give a new answer or can assuage my uneasiness about one or more of those answers to the linked question.  The top answer is by joshphysics.  The part about forces (and masses) is his statement of the third law: " If any two objects are being observed in a local inertial frame, then their accelerations will be opposite in direction, and the ratio of their accelerations will be constant."  Here he implicitly assumes that two objects in an inertial frame will be accelerating.  So I think he just forgot to add that there must also be so interaction (force) between the two objects.  If we assume that there is an interaction between the two objects then this is just Newton's regular old third law (pretty much).  However, this definition only provides a means of measuring mass if the accelerations of the two bodies are completely due to the single interaction between the two objects.  I'm not entirely sure I understand his second law and so let's move on.  The second answer is by Cleonis.  His second law is the standard second law.  Cleonis claims that he's defining force and mass but he doesn't (well he does seem to imply that given a known force that mass is just a constant of proportionality in the last sentence of his third-to-last paragraph before the additional remarks -- but without a way of measuring force, it's not useful) -- so that's a bit disappointing.  Constantine then defines force as the time derivative of momentum.  Even if we leave force as a primitive we still need a method of measuring the mass of an object in any given system.  His method of defining it in a system of two particles doesn't work if we have more than two particles so it has a very limited applicability.


There have been a few questions already that I have found addressing the issue of embedding text into an equation environment, however I haven't managed to get any f the solutions to work in my case. Most people suggest using \text to isolate the text, but this doesn't format well if I have a long paragraph of text. Can anyone suggest a neater method for this?  My code is as follows:  We are concerned here with the following Cauchy problem for timelike, maximal cylinders   \documentclass{article} \usepackage{amsmath, amsthm, amsfonts} \newcommand{\fii}{\varphi} \begin{document}     \begin{equation} \label{CP} \tag{CP}     \begin{split}     \text{Given an initial, smoothly immersed curve}\ s\mapsto (\fii_0(s),0) \in M \text{satisfying} \\     \fii_0(s)=\fii_0(s+1), \text{and a smooth, uniformly timelike vector field}\ X(s)\in T_{(\fii_0(s),0)}M \\     \text{along the curve, find a time}\ T\in (0,\infty] \text{and a smooth, maximally immersed cylinder} \Sigma \\     \text{which may be parametrized such that}\ \fii(s,0)=\fii_0(s) \text{and such that}\ X(s)\in T_{(\fii_0(s),0)}\Sigma     \end{split}     \end{equation}   \end{document}   and here is the output!

I want to be able to  write the following in LaTeX      We make the further assumption that \begin{equation} \label{eqn:assumption} There is a bounded linear operator     $B:X\to X^*$ such that $B^*=B$ and the operator $JB$ is an extension of $T'(0)$\end{equation}   and get a nice output, in such a way that this whole chunk of text along with the math can be referenced later. Of course I can write text inside the equation environment using \text{}, but when I tried this the spacing was all wrong. Can anyone suggest a solution to this?


Does there exist a model of $ZF¬C$ in which there is a function $f:\mathbb R \to \mathbb R$ such that $f$  is sequentially continuous at some $a \in \mathbb R$ but not $\epsilon-\delta$ continuous , i.e., for any sequence $\{x_n\}$ converging to $a$ , $\lim f(x_n)=f(a)$ but still $f$ is not continuous at $a \in \mathbb R$ ?

In my introductory Analysis course, we learned two definitions of continuity. $(1)$ A function $f:E \to \mathbb{C}$ is continuous at $a$ if every sequence $(z_n) \in E$ such that $z_n \to a$ satisfies $f(z_n) \to f(a)$. $(2)$ A function $f:E \to \mathbb{C}$ is continuous at $a$ if $\forall \varepsilon>0, \exists \delta >0:\forall z \in E, |z-a|<\delta \implies |f(z)-f(a)|<\varepsilon$. The implication $(2)\implies(1)$ is trivial (though I will happily post a proof if there is sufficient interest).  The proof of the implication $(1)\implies(2)$ is worth remarking on, though. Proof that $(1)\implies(2)$: Suppose on the contrary that $\exists \varepsilon>0:\forall \delta>0, \exists z \in E:\left (|z-a|<\delta \; \mathrm{and} \; |f(z)-f(a)|\ge \varepsilon\right )$.  Let $A_n$ be the set $\{z\in E:|z-a|<\frac{1}{n} \; \mathrm{ and }\; |f(z)-f(a)|\ge\varepsilon\}$.  Now use the Axiom of Choice to construct a sequence $(z_n)$ with $z_n \in A_n \; \forall n \in \mathbb{N}$.  But now $a-\frac{1}{n}<z_n<a+\frac{1}{n}\; \forall n \in \mathbb{N}$ so $z_n \to a$.  So $f(z_n) \to f(a)$.  But $|f(z_n)-f(a)|\ge\varepsilon\; \forall n \in \mathbb{N}$, which is a contradiction. You will have noticed that the above proof uses the Axiom of Choice (the lecturer didn't explicitly spell out the dependence, but it's definitely there).  My question is: is it possible to prove that $(1) \implies (2)$ without using the Axiom of Choice.  I strongly suspect that it isn't.  In that case, can anyone prove that we have to use the Axiom of Choice?  I can think of three ways to do this: (A) Show that $\left( (1) \implies (2)\right)\implies \mathrm{AC}$.  I suspect that this statement is untrue. This is definitely untrue, as Arthur points out, because I only used the axiom of countable choice, which is strictly weaker than AC. (B) Show that $(1)\implies (2)$ is equivalent to some other statement known to require the Axiom of Choice (the obvious example being the well-ordering of the real numbers). (C) Construct or show the existence of a model of ZF in which there exist sequences which satisfy $(1)$ but not $(2)$. Of course, if anyone can think of another way, I would be very interested to hear about it. One final note - I am aware that very many theorems in Analysis use the Axiom of Choice in one way or another, and that this is just one example of such a theorem.  If there exists a model of ZF like the one described in (C), is the study of Analysis in that model interesting?


I have a couple of wave modifiers on a mesh.    As you can see, all the values in the modifier options are exactly the same, apart from Offset.  Is there a more convenient way of changing one value for all of the modifiers (e.g. increasing Speed) without manually doing it for each one?  Thanks for any help given.

I have an object that I want to make a square array like a 3x3x3 cube. I want be able to change length and count for one axis and have all the other ones follow.


I want to install a new package so, I need to sudo apt-get -y upgrade but it just keeps going on and on and on with the below output. I am not able to understand the concepts of sudo apt-get. I mean update/upgrade. Please help me. Note:-  Editing this because it completed after 1:30 hours but it causes few problems. My system behaves strangely. My fonts got changed, all system icons changed how can i get back my system fonts and icons? Unpacking fonts-lohit-telu (2.5.5-2) over (2.5.5-1) ... Preparing to unpack .../327-fonts-noto-cjk_1%3a20190410+repack1-2_all.deb ... Unpacking fonts-noto-cjk (1:20190410+repack1-2) over (1:20190410+repack1-2) ... Preparing to unpack .../328-fonts-opensymbol_2%3a102.11+LibO7.0.0~rc2-1_all.deb ... Unpacking fonts-opensymbol (2:102.11+LibO7.0.0~rc2-1) over (2:102.11+LibO6.4.3-0ubuntu0.20.04.1) ... dpkg: warning: unable to delete old directory '/usr/share/fonts/truetype/openoffice': Directory not empty Preparing to unpack .../329-fonts-sarai_1.0-3_all.deb ... Unpacking fonts-sarai (1.0-3) over (1.0-2) ... Preparing to unpack .../330-fonts-telu-extra_2.0-5_all.deb ... Unpacking fonts-telu-extra (2.0-5) over (2.0-4) ... Preparing to unpack .../331-fonts-tlwg-garuda-ttf_1%3a0.7.2-1_all.deb ... Unpacking fonts-tlwg-garuda-ttf (1:0.7.2-1) over (1:0.7.1-3) ... Preparing to unpack .../332-fonts-tlwg-garuda_1%3a0.7.2-1_all.deb ... Unpacking fonts-tlwg-garuda (1:0.7.2-1) over (1:0.7.1-3) ... Preparing to unpack .../333-fonts-tlwg-kinnari-ttf_1%3a0.7.2-1_all.deb ... Unpacking fonts-tlwg-kinnari-ttf (1:0.7.2-1) over (1:0.7.1-3) ... Preparing to unpack .../334-fonts-tlwg-kinnari_1%3a0.7.2-1_all.deb ... Unpacking fonts-tlwg-kinnari (1:0.7.2-1) over (1:0.7.1-3) ... Preparing to unpack .../335-fonts-tlwg-laksaman-ttf_1%3a0.7.2-1_all.deb ... Unpacking fonts-tlwg-laksaman-ttf (1:0.7.2-1) over (1:0.7.1-3

Updated Ubuntu 16.04 today using the software updater. Now my PC is running Kali? There were something like 2Gb of updates, which I thought at first was because I haven't updated in a while. Now I'm thinking that it was downloading Kali. Here's a  of the new boot-up process.  The screen will continue to flicker for another 30 seconds or so, then stop flickering leaving the text on the screen. I tried switching the display manager from gdm to lightdm, which will boot me straight to the console and without flickering, but still no desktop.  I'm not altogether sure how I managed to accomplish this. It must have been when I was trying to get Katoolin running.  Any tips as to how I can either get the desktop or revert the updates?  Contents of cat /etc/lsb-rolling:  DISTRIB_ID=Kali DISTRIB_RELEASE=kali-rolling DISTRIB_CODENAME=kali-rolling DISTRIB_DESCRIPTION="Kali GNU/Linux Rolling"


Do you know if there is some Whatsapp client on Ubuntu for mobile phones? I would want to use it. Thanks in advance.

Does someone know if there already is a WhatsApp Version for Ubuntu Phone? I decided to install Ubuntu on my Android, but I don't want to use my phone without WhatsApp.


Please, the memory and the cache are getting to the full level quite quickly under my linux mint 9 - isadora system. I used Ubuntu and Debian before, and it was not causing this issue at all. At the current time i typing the following command frequently to empty the cache "echo 3 > /proc/sys/vm/drop_caches".   Please any way around this? or do you know what's going wrong? | I am only programming on this machine; no graphics, no games nothing.  Thanks in advance for your help!

This is a  about how Unix operating systems report memory usage.   Similar Questions:                    I have production server that is running Debian 6.0.6 Squeeze  #uname -a  Linux debsrv 2.6.32-5-xen-amd64 #1 SMP Sun Sep 23 13:49:30 UTC 2012 x86_64 GNU/Linux   Every day cron executes backup script as root:  #crontab -e  0 5 * * * /root/sites_backup.sh > /dev/null 2>&1   #nano /root/sites_backup.sh  #!/bin/bash str=`date +%Y-%m-%d-%H-%M-%S` tar pzcf /home/backups/sites/mysite-$str.tar.gz /var/sites/mysite/public_html/www mysqldump -u mysite -pmypass mysite | gzip -9 > /home/backups/sites/mysite-$str.sql.gz cd /home/backups/sites/ sha512sum mysite-$str* > /home/backups/sites/mysite-$str.tar.gz.DIGESTS cd ~   Everything works perfectly, but I notice that Munin's memory graph shows increase of cache and buffers after backup.  Then I just download backup files and delete them. After deletion Munin's memory graph returns cache and buffers to the state that was before backup.  Here's Munin graph:  Externally hosted image was a dead link.


I accidentally moved my slide pane in Impress from the left side and I don't know how to put it back.

I accidentally moved a pane in LibreOffice from it's nice docked position to a new window. Now I can't move back it.    As you can see, the Slide Pane is floating as it's own window and not docked like Tasks, etc.


Can the above argument be valid?  If it can, I want to know why, as far as I see, even though the conclusion (no squares are circles.) is true, it doesn't seem to be following the premises (not a fallacy?)

Given this definition:     A deduction is valid if and only if its conclusion is true whenever all of its hypotheses are true.   Can an argument be valid if it has a tautology as a conclusion?  An example I can think of is:        A proposition is either a tautology or not a tautology   (1) is a proposition   (1) is either a tautology or not a tautology      That seems strange/wrong to me, even though it appears to meet the definition. Are there other conditions for an argument to be valid?


When I try to install Wine, PlayonLinux, and some other programs, I get the following message:  At the terminal:  The following packages have unmet dependencies:  wine : Depends: wine1.5 but it is not going to be installed E: Unable to correct problems, you have held broken packages.   At the software center:  Package dependencies cannot be resolved This error could be caused by required additional software packages which are missing or not installable. Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time.   I already tried installing them with "aptitude" and failed.  I am running Ubuntu 12.10  Please help! I've had this problem for a while now and don't know what to do!

I upgraded on a fresh install to Ubuntu 12.10, and I've tried installing wine many times, but I always get this:  This error could be caused by required additional software packages which are missing or not installable.  Furthermore there could be a conflict between software packages which are not allowed to be installed at the same time. The following packages have unmet dependencies:  wine:   It won't let me install the dependencies either it says it needs another set of dependencies to install them. Using Asus KJ50 64bit OS, dual boot with Windows 7  sudo apt-get install wine1.5 Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  wine1.5 : Depends: wine1.5-i386 (= 1.5.15-0ubuntu1) but it is not installable            Recommends: gnome-exe-thumbnailer but it is not going to be installed or                        kde-runtime but it is not going to be installed            Recommends: ttf-droid            Recommends: ttf-mscorefonts-installer but it is not going to be installed            Recommends: ttf-umefont but it is not going to be installed            Recommends: ttf-unfonts-core but it is not going to be installed            Recommends: winbind but it is not going to be installed            Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages.


Find the integral   $$\int_{0}^{\infty}\frac{dw}{1+\left ( \frac{w}{B} \right )^4}$$   where $B$ is a constant.   This integration i tried by normal method that gives the result $\frac{\pi B}{2\sqrt2}$ but it goes so lengthy      is there any signal properties that i use to solve it in simple steps?

How to compute      $$\int_0^{+\infty} \frac{dt}{1+t^4} = \frac{\pi}{2\sqrt 2}.$$   I'm interested in more ways of computing this integral.   There is always the straight forward method to decompose into simple elements  $\dfrac{1}{(1 + t^{4})}$ it works but it is tedious. If someone has a faster and clever method, I'm interested :)  Update :   My quesion is different than  because all the solution that state there is talk about the the straight forward method to decompose into simple elements $\dfrac{1}{(1 + t^{4})}$ as i said before i'm not intersted in that way


I came to know that there is some technical limitation for porting Salesforce1 Lightning App on Desktop UI.   My requirement is to replace existing VF pages with Lightning components.   Can someone please guide me / help me to understand whether this is possible or not?   If not possible, then what is the technical Limitation for porting Salesforce1 Lightning on Desktop UI.  Thanking you in advance for all your cooperation.  With regards, Sudipta Deb

I have looked through the  and , and I have started building some Lightning Applications.  I still do not understand what makes Lightning Applications better than standard VisualForce. What do Lightning Applications do better than VisualForce Pages? What types of problems are they worse at handling? So far in my experience, there does not appear to be much upside, but perhaps there is something I am missing. Thanks!


I can’t get the scroll bar to show on this system. I can just about see it, but it’s hard to click on it to move it. How can I fix this?

It looks like Ubuntu 11.04 will come with  by default. I do like them, but I don't like the current mix of scrollbar types as many applications don't yet use those overlay scrollbars.  Is there a way to disable overlay scrollbars (without removing the overlay-scrollbar package)?


Calling a java class file using batch file works fine.    Here is the code which is working.  public class TestA {  public static void main(String[] args) {     new TestA().printA(); }  public void printA(){     System.out.println("This is A...");      try {          File file = new File("D:/FileA.txt");          boolean fvar = file.createNewFile();          if (fvar){               System.out.println("File has been created successfully");          }          else{               System.out.println("File already present at the specified location");          }         } catch (IOException e) {             System.out.println("Exception Occurred:");             e.printStackTrace();       } } }   The same above code if I put it on scheduling using task executors and try calling the same file using batch file, it's not working ( I mean here file creation is not happening). Need your help on this.  Code with scheduling:  public class TestD implements Runnable {      private ScheduledExecutorService executor = null;      @Override     public void run() {         try {              File file = new File("D:/FileD.txt");              boolean fvar = file.createNewFile();              if (fvar){                   System.out.println("File has been created successfully");              }              else{                   System.out.println("File already present at the specified location");              }             } catch (IOException e) {                 System.out.println("Exception Occurred:");                 e.printStackTrace();           }     }      public void executeScheduler() throws SQLException {         executor.scheduleAtFixedRate(this, 2, 5, TimeUnit.SECONDS);     }      public static void main(String args[]){         TestD testD = new TestD();         try {             testD.executeScheduler();         } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }     }  }   I wrote the code to create a file just to test if my code is being called from the batch file or not, as I couldn't observe the system out statements which are shown in cmd prompt in a jiffy.  Edit: The reason for this problem is due to NullPointerException but the exception is not able to capture as I'm calling the file using batch and the cmd window not showing the error or probably it's showing the error but not human capturable and window closes in fraction of a second. So I don't think this question is a duplicate of

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


Will using two substitution ciphers one after the another be more secure than using single substitution cipher?

This is hypothetical as I can't think of any reason to do this, but out of curiosity...  Could I, for example, take the MD5 digest of a message and concatenate it with the SHA-1 digest (not quite broken, but getting close), to form a secure concatenated digest? Intuitively, I would think the chances of finding a collision that crossed the two algorithms would be low enough to make this secure, but I'm not sure how to verify that.


In the following sentence, I'm not sure whether the noun should be considered plural or singular?     A grid pattern of streets (Main, Elm, First) are shown.   Or:     A grid pattern of streets (Main, Elm, First) is shown.   The grid is clearly singular, but streets is plural.  I'm thinking it should be singular because the grid contains the streets, but am not sure.  Which one is correct?

Possible Duplicate:          When I'm referring to a group of multiple things, should it be considered singular or plural for the purposes of applying a verb to it?  For example, which is correct in the examples below?     A sentence is a group of words that is followed by a period.   A sentence is a group of words that are followed by a period.      The group of people constitutes a jury.   The group of people constitute a jury.      A group of crows is called a 'murder'.   A group of crows are called a 'murder'.   My instinct is that it depends on whether the verb is referncing the group itself or the members of the group directly, but is that right?


I am working in a ERP where the elements id are changing/rotating randomly. so if I am writing a code to locate a id, next time I run the selenium code it gets me error as the id changes by that time  How to capture the ids everytime

How to Handle Dynamic Changing IDs In XPath? for example :   //div[@id='post-body-3647323225296998740']/div[1]/form[1]/input[1]   In this xpath id "3647323225296998740" is changing every time when reloading the page.   Is there any way to handle this type of situation in Selenium?


public class test {     public static void main(String[] args) {             System.out.println(0.3+0.6); } }   The output of the above java code is 0.8999999999999999. Why is that?

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


There are some initialisms out there that are unpronouncable as words in any correct English sense (I found one today of ). However the inventor of such terms force a word onto them, in this case:     The SQRL system (pronounced “squirrel”)   Unless you were aware of this term, and the authors intended pronunciation of it you would pronounce it as letters 'S-Q-R-L'. But that is not how the author intends.  So, if these terms that would clearly be initialisms in any normal sense of the word, but have had a pronunciation forced upon them, can these be referred to as an Acronym?  (This is sort of related to the question: , although that post seems to stem from a misunderstanding of the difference between initialism and acronym so the answers reflect that misunderstanding rather than this particular situation)

One definition of an  is:     An abbreviation formed by (usually initial) letters taken from a word or series of words, that is itself pronounced as a word, such as RAM, radar, or scuba; sometimes contrasted with initialism.   An  is:     A term formed from the initial letter or letters of several words or parts of words, but which is itself pronounced letter by letter.   If I pronounce an initialism, as a word, and not just as letters, does that 'make' it an acronym?


Through the code, I will wish my redirect the user to an absolute url.  I tested with drupal_goto () but it only works with relative urls. I wish to go to another domain that current_domain  thank you

When writing a module, for redirecting to Drupal paths, one uses drupal_goto.  Is there some API function that I should use for redirecting to external pages? Or is setting the Location with drupal_set_header the way to go?  PS I have to do some processing on the request; mod_rewrite/mod_alias on Apache-level or the Drupal Path redirect module, don't solve my problem.


I want to implement a selection menu in bash (version 3.2 on macOS) which would output something like this: Select a fruit:   0  Nothing   1  A banana   2  An orange  When the user will choose an item, I want to be able to run an associated bash script. For this, I would need something like a 2-dimension array but if I am not wrong it does not exist in bash. I thought about using several arrays in a main array. Then I would use a loop to display the menu to the user: #!/usr/bin/env bash  item_nothing=("0" "Nothing" "") item_banana=("1" "A banana" "select_banana.sh") item_orange=("2" "An orange" "select_orange.sh") items=(     "item_nothing"     "item_banana"     "item_orange" )  printf "Select a fruit:\n" for item in "${items[@]}"; do     printf "$(\$$item[0])"     printf "$(\$$item[1])\n"     # $(\$$item[2]) done  When I run my script I get the following output: Select a fruit: ./fruit_selection.sh: line 14: $item_nothing[0]: command not found ./fruit_selection.sh: line 15: $item_nothing[1]: command not found  ./fruit_selection.sh: line 14: $item_banana[0]: command not found ./fruit_selection.sh: line 15: $item_banana[1]: command not found  ./fruit_selection.sh: line 14: $item_orange[0]: command not found ./fruit_selection.sh: line 15: $item_orange[1]: command not found  I have no idea what I am doing wrong. Would you have a solution to achieve what I describded? Also, if you have a better way than what I started to do, do not hesitate to suggest it.  EDIT: solution below in the for loop #!/usr/bin/env bash  item_nothing=("0" "Nothing" "") item_banana=("1" "A banana" "select_banana.sh") item_orange=("2" "An orange" "select_orange.sh") items=(     "item_nothing"     "item_banana"     "item_orange" )  printf "Select a fruit:\n" for item in "${items[@]}"; do     var_0=$item[0]     var_1=$item[1]     printf "  ${!var_0}  "     printf "${!var_1}\n"      # var_3=$item[3]     # do something with this later "${!var_3}\n" done

I have two arrays:  arrayA=(1 2 3) arrayB=(a b c)   and I want to print out one of them using a command line argument, i.e., without any if else.  I tried a few variations on the syntax with no success. I am wanting to do something like this:  ARG="$1"  echo ${array${ARG}[@]}   but I get a "bad substitution" error. How can I achieve this?


My spouse is considering becoming a stay-at-home parent. They currently work and have a 401k. If they do leave their job, and want to rollover the 401k, what's the best investment vehicle to choose? Is a traditional IRA the right answer?

I recently started a new job and have a 401k from my previous employer that I don't know what to do with.  Should I roll it into my new employer's 401k, a traditional IRA or a Roth IRA?


I am really new to Javascript and this might be a really dumb question but how do you type an apostrophe in between an object?  const data = {  greeting: 'Welcome to John's restaurant' }   Do I need to write something in front of it? Thank you in advance

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.


Sometimes, but not always, after taking shots with my Nikon D3100 it will show the preview on the camera screen and when I go to put them on the computer it will say incomplete file. I am wondering if anyone else is seeing this and if there is a reason for it?

I have had my Nikon D40 for a while, and some of the pictures are coming out distorted. Two examples are below:   So my questions are:    How do I fix them after the fact? - i.e. after they have been imported from the camera - if possible How do I prevent future pictures from being distorted like this?   Thanks   and


I am trying to setup replication between MariaDB 10.4.17 and Aurora 5.7.12 MySQL, with Mariadb as master and aurora as replica. I am following this  I noted the file name and position +---------------+----------+--------------+------------------+ | File          | Position | Binlog_Do_DB | Binlog_Ignore_DB | +---------------+----------+--------------+------------------+ | binlog.000169 |  1387829 |              |                  | +---------------+----------+--------------+------------------+  I created mysql dump from mariadb and loaded that into aurora. after which I created a replication user on the master instance like this CREATE USER 'replication_aurora'@'%' IDENTIFIED BY 'repl_pass'; GRANT REPLICATION CLIENT, REPLICATION SLAVE ON *.* TO 'replication_aurora'@'%'; and called the procedure on Aurora CALL mysql.rds_set_external_master ('ip of master', 3306,     'replication_aurora', '<password>', 'binlog.000169', 1387829, 0);  more about the above procedure  then i called this procedure CALL mysql.rds_start_replication;  This was supposed to start replication but I am getting this when i run SHOW SLAVE STATUS \G; *************************** 1. row ***************************                Slave_IO_State:                   Master_Host: master_ip                   Master_User: replication_aurora                   Master_Port: 3306                 Connect_Retry: 60               Master_Log_File: binlog.000169           Read_Master_Log_Pos: 1387829                Relay_Log_File: relaylog.000001                 Relay_Log_Pos: 4         Relay_Master_Log_File: binlog.000169              Slave_IO_Running: No             Slave_SQL_Running: Yes               Replicate_Do_DB:           Replicate_Ignore_DB:            Replicate_Do_Table:        Replicate_Ignore_Table: mysql.rds_replication_status,mysql.rds_monitor,mysql.rds_sysinfo,mysql.rds_configuration,mysql.rds_history       Replicate_Wild_Do_Table:   Replicate_Wild_Ignore_Table:                    Last_Errno: 0                    Last_Error:                  Skip_Counter: 0           Exec_Master_Log_Pos: 1387829               Relay_Log_Space: 2754               Until_Condition: None                Until_Log_File:                 Until_Log_Pos: 0            Master_SSL_Allowed: No            Master_SSL_CA_File:            Master_SSL_CA_Path:               Master_SSL_Cert:             Master_SSL_Cipher:                Master_SSL_Key:         Seconds_Behind_Master: NULL Master_SSL_Verify_Server_Cert: No                 Last_IO_Errno: 1593                 Last_IO_Error: Fatal error: The slave I/O thread stops because a fatal error is encountered when it tries to get the value of SERVER_UUID variable from master.                Last_SQL_Errno: 0                Last_SQL_Error:   Replicate_Ignore_Server_Ids:              Master_Server_Id: 1                   Master_UUID:              Master_Info_File: mysql.slave_master_info                     SQL_Delay: 0           SQL_Remaining_Delay: NULL       Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates            Master_Retry_Count: 86400                   Master_Bind:       Last_IO_Error_Timestamp: 210424 15:42:38      Last_SQL_Error_Timestamp:                Master_SSL_Crl:            Master_SSL_Crlpath:            Retrieved_Gtid_Set:             Executed_Gtid_Set:                 Auto_Position: 0          Replicate_Rewrite_DB:                  Channel_Name:            Master_TLS_Version:  I am thinking error could be while creating the user I created 'replication_aurora'@'%' instead of creating 'replication_aurora'@'replica ip' is this the issue? I am unable to check because the connection endpoint aurora gives is more than 60characters long so i cannot create a user with that endpoint on my mariadb master. Question.  is not giving replica ip in user is the issue? is compatibility the issue? should i also create the same user on replica?  I am sort of at a dead end here please help any article or video would be helpful

Im trying to setup replication between mariadb(10.1.31-MariaDB - MASTER) and mysql(5.7.12-log - SLAVE). After executed the start slave, I got the below error.     Fatal error: The slave I/O thread stops because a fatal error is   encountered when it tries to get the value of SERVER_UUID variable   from master.   Then I tried to get the value of master_uuid.  MariaDB [(none)]> show variables like '%server_uuid%'; Empty set (0.00 sec)   Then tried to setup this in mysql prompt.  MariaDB [(none)]> set global  server_uuid = 11123c25-cac0-3523-8089-4c54d9b46f33; ERROR 1193 (HY000): Unknown system variable 'server_uuid'   And also I tried to setup auto.cnf in data directory.  [auto] server_uuid = 11123c25-cac0-3523-8089-4c54d9b46f33  chmod 644 auto.cnf   But still im getting the fatal error is encountered when it tries to get the value of SERVER_UUID variable from master.


I am adding objects to an ArrayList that is initialized as null inside a for each loop, but SonarLint is giving me a "NullPointerException" could be thrown when I try to add each object. Why is this error being pointed out?   public List<SatelliteData> getData()   {     SatelliteData satellite;     ArrayList<SatelliteData> satelliteList = null;      try(FileInputStream file = new FileInputStream(satelliteOutputFile))     {       TLEParser parsedFile = new TLEParser();       List<TLE> tleList = parsedFile.readFile(file);        for (TLE tle : tleList)       {         satellite = new SatelliteData(tle);         satellite.collectSatelliteData();          satelliteList.add(satellite); //A "NullPointerException" could be thrown; "satelliteList" is nullable here       }      }     catch (IOException ex)     {       LOGGER.error("IO Exception: " +  ex);       notifyTheObservers("IO Exception: " + ex);     }      return satelliteList;   }

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


(1 ≤ N ≤ 1e+5) I have to find how many cases in this condition: i < j and array[i] > array[j] here I have tried: k = int(input()) n = tuple(map(int, input().split())) h=0 i=0 j=0 for j in range(k-1):     for i in range(j+1,k):         if n[j]>n[i]:             h+=1 print(h)  but it gives time limit. is there better way to iterate it. Test case 1: 10 7 6 2 4 1 5 10 3 9 8

I'm designing an algorithm to do the following: Given array A[1... n], for every i < j, find all inversion pairs such that A[i] > A[j]. I'm using merge sort and copying array A to array B and then comparing the two arrays, but I'm having a difficult time seeing how I can use this to find the number of inversions. Any hints or help would be greatly appreciated.


I'm currently studying and would like to know if there are any actual benefits of using a mixture of activation functions for each layer. For example, if I am trying to predict the probabilities of each class occurring given a certain row of data. A 4 layer network will be implemented having ReLu activation for Hidden layer 1, Sigmoid activation for Hidden layer 2 and finally Softmax activation for the Output Layer.  Since ReLu Activation is used in my 1st hidden layer and as it will only generate 0 and above values, are there any possible benefits of doing this? Maybe the benefit of sparsity for instance?

I have been told by a professor that it is not possible to combine different activation functions within a neural network.  And I can't find any examples of anyone doing this.  However, I cannot find any good explanation why.   Conceptually, it seems to make sense:  suppose I have a set of data on some population.  Imagine the population is divided into two types of people, A and B, but I don't actually have that categorical variable in my data.  We could imagine a logistic model that maps my population data into the categorical variable.  Now suppose I'm training a neural net with one hidden layer.  It seems to me that it makes perfect sense for one node in that hidden layer to have a sigmoid function as input representing the transformation of the input variables to this latent categorical variable (now as a probability, of course).  Meanwhile, all the other nodes have a linear activation function.  And then output would be a linear function of all the nodes in the hidden layer.    I have no reason to assume this would improve prediction error.  This is what I want to know:  is it possible to estimate such a model using standard approaches?


In Nolan's Dark Knight Trilogy,how many people in total actually know that Bruce Wayne is Batman?

In Batman Begins, very few people knew about the true identity of Bruce Wayne, but as the series progressed the number of people knowing this fact dramatically increased.  Can you provide the list of all the people who knew about his true identity by the end of The Dark Knight Rises?


Suppose you have an ARM embedded device and a x64 based laptop. Both systems are running GNU/Linux. If you decide to copy the "ls" binary from the laptop to the embedded device and run it on the embedded, will it work? Explain your reasoning.

Is it possible to convert/recompile an already compiled x86 binary into an ARM binary?   I'm using a  with a command-line Ubuntu (Maverick) and want to run a  server but the x86 executable they supply cannot be run on the hardware as far as I can tell (most likely due to differing architecture).  Unfortunately I don't have access to the source to allow me to recompile it natively.  If not, is there any other way I can get the binary to run (emulation for example)?


Lots of people have been moving out of my hometown. I rarely have seen anyone I know.   Can you use "someone" instead of anyone?  If not, please explain why. Thank you!

Can anyone explain the difference between: "Can anyone answer me "  and "Can someone answer me " ?


I am checking to see if an object is null before using it like this   if (resturant.getLat() != null)    //do stuff   But it is throwing a java.lang.NullPointerException how can I check that restaurant.getLat() is not null?  Thanks


The following test fails:  @Test public void testRound() throws Exception {     double v = 0.015d;     DecimalFormat format = new DecimalFormat("#.##", new DecimalFormatSymbols(Locale.US));     format.setRoundingMode(RoundingMode.HALF_UP);     assertEquals("0.02", format.format(v)); }   I see that there are resolved issues for  and , but it still doesn't work for me on "jdk1.8.0_144":  junit.framework.ComparisonFailure: null  Expected :0.02 Actual   :0.01

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


A character is at 0 HP with two failed death saving throws and is lying unconscious on the ground, sharing the same area with the effect of the Healing Spirit spell.   What happens at the beginning of their turn? How do the timing of these effects interact?  I couldn't find any official guidance from a few internet searches, so the GM made a ruling at the time, but is there any official answer as to what should happen?  As far as I can see, the options are:   The character is healed for 1d6 hit points and therefore stabilized, and doesn't need to take a death saving throw The character makes a death saving throw and either succeeds or fails, which may result in their death. If they're still alive, they're healed for 1d6 and stabilize.   Healing Spirit's effect:     Until the spell ends, whenever you or a creature [...] starts its turn there, you can cause the spirit to restore 1d6 hit points to that creature   Death saving throw rules:     Whenever you start your turn with 0 hit points, you must make [...] a death saving throw

There exist multiple spells/effects/mechanics that can trigger on the start of a character's turn. How in general should a DM rule the ordering, in cases where the order will matter?  As an example: Alice has been downed. She has 0 hit points and has been making death saving throws for a few turns now. She currently has 2 successes and 2 failures. She is also in the area of effect of a Cloudkill spell, which crucially has the following effect:     When a creature enters the spell's area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 5d8 poison damage on a failed save, or half as much damage on a successful one.   At the start of Alice's next turn, one of two things could happen, either:  The death saving throw goes first, in which case she has a straight 50/50 of surviving this situation (for now!) or dying right then and there. If she is lucky and gets her third success, the cloudkill is still a concern, but not a matter of life and death. Worst case she is put back into an 'unstable' state but her death saves are reset, buying her precious more time to be saved or evacuated by her party.   or:  The cloudkill check goes first, she dies instantly. Since no matter how well she does on the save to resist it, at best she still takes half damage, and any amount of damage is enough to permanently kill her whilst sitting on two failed death saves.   So whilst in many cases the order of 'start of turn' effects might not matter, in at least this example we have a case where the permanent death of a character could be drastically effected by the order ruled by the DM.   So how should a DM rule the ordering of such effects?


For which prime numbers p does the congruence $x^2 + x + 1 \equiv 0 \pmod{p}$ have solutions?  We've recently learnt about quadratic reciprocity in class, however I am not sure how to tackle this problem. I have tried starting with the $b^2-4ac$ (discriminant) but that hasn't really helped.

I think it's enough to search for the prime numbers where $x^2+x+1=0$ is not solvable, but I am not sure where to start. Thank you


Weird question probably, but this is the part where I elaborate!  Lets say I have a plane and subdivide it with 4 so that the plane is now a grid of 5x5 faces.  Is there some magical script or perhaps built-in way to have it so that when I move the central face, perpendicular faces are generated to prevent surrounding faces from deforming? Pic attached. Left portion is normal behavior, right portion is desired behavior. Which would occur regardless of what face is extruded.   So basically when any given face is moved, rather than the adjacent faces being deformed, perpendicular ones are generated.

So I have subdivided a face on a cube 9 times and I want to pull a certain area of the face backwards into the cube to make eyes. However, when I select certain vertices and bring them back, they pull the faces surrounding them back as well so they are slanted. Is there a way to only bring the faces that I selected back, so new faces are created on the side?  Thanks in advance!


Is there any (new) research on whether to go with horizontal or vertical navigation on mobile-responsive saas apps? I've seen a bunch of articles from 3-5 years ago and was trying to see if anyone had a more recent perspective.   Our situation is below:  1) B2B SaaS Product (web based app like Workday or ZenDesk)  2) Web & Mobile (Hybrid App)

I've seen many sites using both horizontal (top) navigation, vertical (left) navigation, and both across web sites for a long time. My understanding is that they're both conventions, but I would assume there must be some data out there supporting one route over the other.   My question is: are any studies or data for or against horizontal or vertical navigation (as suggested above) with regards to primary navigation (specifically on a smaller site or web app).  I've read some interesting things that are flipping me back and forth between liking horizontal more than vertical and vice versa. For example if you look at Jacob Nielsen's post on  you get the feeling that more important content should be on the left -- but you could take that as it being more important for the navigation (the user's escape routes) to be in that valuable space.


Is there any application that can track our activities on Linux system, actually I want to know my history of what I'm doing.   Example : opened Firefox at 10: 20 am opened gramps at 10 : 50 an   So we can see our these actives and we can know what we have done on this time, how many long and etc. There such application for tracing time like Project Hamster, but its not automatically track what we are doing. or maybe there is and advanced one that can include what we are doing inside application like :    In Firefox opened google.com at 10:20 PM opened yahoo.com at 04:00 AM

How can we measure that in a given period, what window was on the top? (active one)  I already tried based on "wmctrl", but I can't show the currently active window.. in the second example I tried with ":ACTIVE:", it showed ALL again, but only the terminal was the active then..  $ wmctrl -l | awk '$2 != "-1"' 0x044006a3  8 notebook Mozilla Firefox 0x0456fb4c  0 notebook How to measure that how much time is the active window opened? - Unix & Linux Stack Exchange - Mozilla Firefox 0x03000004  0 notebook Terminal $  $ wmctrl -l :ACTIVE: | awk '$2 != "-1"' 0x044006a3  8 notebook Mozilla Firefox 0x0456fb4c  0 notebook How to measure that how much time is the active window opened? - Unix & Linux Stack Exchange - Mozilla Firefox 0x03000004  0 notebook Terminal $    Purpose: The output would be something like this (from an example 8 hour shift, so 480 minutes):   MINUTE  TASK 195 Mozilla Firefox 165 Terminal 74  Thunderbird 36  Idle (was away, machine locked, no app was on top..) 10  Unknown (the machine wasn't powered on)   With the awk '$2 != "-1"' I just excluded the "Bottom Expanded Edge Panel".   Question: I only need the part that how can I show the currently active window. I can do the part where I run a script in ex.: every 10 seconds and gather the time information.   p.s.: I'm using Ubuntu 12.04 or CentOS 6 both with GNOME.


When there is a phrase like "the page of the book," is it correct to put both the in the sentence? What are the rules in general? What if we had more OF in the sentence? e.g. "the room of the department of the organization"

I can’t for the life of me figure out where to use a and where to use the — and where there is no article at all. Is there a simple rule of thumb to memorize?   The standard rule you always hear:     “If a person knows which item you are talking about then use "the"   . . . doesn’t clear things up for me, as I have no idea whether or not they know.


Prove or disprove. Let $G$ be an abelian group. Let $N \triangleleft G$. Then,    $$ G\cong N \times G/N. $$   I tried to prove this claim, but then it seems that since $G$ is abelian then every subgroup is normal. So every group can be factored as above. But I did not find a counter example.  Any suggestions?  Thanks for helpers!

If $A$ is abelian group and $B$ is a subgroup of $A$, $B$ is normal subgroup of $A$.  Is it true that $B \times A/B \cong A$?  I ask because I was watching an online lecture from a course in abstract algebra at Harvard extension school.   And the lecturer (whose name is Peter) was taking about vector spaces and said that if $V$ is a vector space and $W$ is a subspace, then $V/W \times W \cong V$.  So the question which I thought of is: "is this true for all Abelian groups?"   Also, is there a less restricted condition on groups which will make this property hold?


Most Stack Exchange sites started off as  proposals, passing through the definition and commitment stages there before moving on to become beta sites and perhaps graduated ones.  Presumably the flagship site SO, and perhaps some of the other oldest sites like Server Fault and Super User, didn't pass through this process. I believe some of the unusual outlier sites, like Stack Apps and , also didn't pass through Area 51.  What is the complete list of Stack Exchange sites which didn't start in Area 51?

Recently I found some sites that are a part of the Stack Exchange network but were not proposed. In other words, I'm talking about sites that are not established through Area51, like Super User.  Which sites are these that are part of the Stack Exchange network and have not been proposed / were not established through Area51?


I have just installed Kubuntu 16.04 using Asia (Rangoon) Timezone. The calendar and some numbers are showing in Myanmar Language.How can I change these language to English while retaining Rangoon Timezone?

How do I set up a global locale for the computer?  I have recently installed Kubuntu 14.04LTS in english but since I am in Spain, I chose Spain as a country and then changed locale options so that I get all country specific configuration such as digit grouping, decimal separator, date format, etc. I also added the spanish language.  Now all applications complain that locale is wrong. check-language-support tells me I'm using en_ES.UTF-8 as system's locale, and that locale is indeed wrong, there is no locale for english language in Spain.  I tried using Kubuntu's country/region & language settings but it doesn't fix it. I tried using export LANG=en_GB.UTF-8 and export LC_ALL=en_GB.UTF-8 and then sudo dpkg-reconfigure locales and that caused check-language-support to say that I now have a correct configuration but if it is, it's only in that konsole session. This problem also prevents konsole from showing unicode characters and I cannot use dead keys or enter any 'international character' such as ñ or ç (those work on other applications such as Firefox, that I'm using to post this question).  So the question is: How do I set up a global locale for the computer?  This is not a bug report, I will probably reinstall my computer eventually if I can't fix it. But I really want to know how I can perform this REALLY basic task.  Thank you.  $ check-language-support perl: warning: Setting locale failed. perl: warning: Please check that your locale settings:         LANGUAGE = "en:es:en",         LC_ALL = (unset),         LC_PAPER = "en_ES.UTF-8",         LC_ADDRESS = "en_ES.UTF-8",         LC_MONETARY = "en_ES.UTF-8",         LC_NUMERIC = "en_ES.UTF-8",         LC_TELEPHONE = "en_ES.UTF-8",         LC_IDENTIFICATION = "en_ES.UTF-8",         LC_MEASUREMENT = "en_ES.UTF-8",         LC_TIME = "en_ES.UTF-8",         LC_NAME = "en_ES.UTF-8",         LANG = "en_ES.UTF-8"     are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_COLLATE to default locale: No such file or directory hunspell-en-ca libreoffice-help-en-gb libreoffice-l10n-en-gb libreoffice-l10n-en-za mythes-en-au wspanish  $ cat /etc/default/locale LANG="en_US.UTF-8" LC_NUMERIC="es_ES.UTF-8" LC_TIME="es_ES.UTF-8" LC_MONETARY="es_ES.UTF-8" LC_PAPER="es_ES.UTF-8" LC_NAME="es_ES.UTF-8" LC_ADDRESS="es_ES.UTF-8" LC_TELEPHONE="es_ES.UTF-8" LC_MEASUREMENT="es_ES.UTF-8" LC_IDENTIFICATION="es_ES.UTF-8"   $ locale locale: Cannot set LC_CTYPE to default locale: No such file or directory locale: Cannot set LC_MESSAGES to default locale: No such file or directory locale: Cannot set LC_ALL to default locale: No such file or directory LANG=en_ES.UTF-8 LANGUAGE=en:es:en LC_CTYPE="en_ES.UTF-8" LC_NUMERIC=en_ES.UTF-8 LC_TIME=en_ES.UTF-8 LC_COLLATE="en_ES.UTF-8" LC_MONETARY=en_ES.UTF-8 LC_MESSAGES="en_ES.UTF-8" LC_PAPER=en_ES.UTF-8 LC_NAME=en_ES.UTF-8 LC_ADDRESS=en_ES.UTF-8 LC_TELEPHONE=en_ES.UTF-8 LC_MEASUREMENT=en_ES.UTF-8 LC_IDENTIFICATION=en_ES.UTF-8 LC_ALL= $ update-locale perl: warning: Setting locale failed. perl: warning: Please check that your locale settings:         LANGUAGE = "en:es:en",         LC_ALL = (unset),         LC_PAPER = "en_ES.UTF-8",         LC_ADDRESS = "en_ES.UTF-8",         LC_MONETARY = "en_ES.UTF-8",         LC_NUMERIC = "en_ES.UTF-8",         LC_TELEPHONE = "en_ES.UTF-8",         LC_IDENTIFICATION = "en_ES.UTF-8",         LC_MEASUREMENT = "en_ES.UTF-8",         LC_TIME = "en_ES.UTF-8",         LC_NAME = "en_ES.UTF-8",         LANG = "en_ES.UTF-8"     are supported and installed on your system. perl: warning: Falling back to the standard locale ("C").


public ActionResult Customer(string fullNameSpace) {     var genType = fullNameSpace.ToGenericType(); //how can I do this?     var clList = _adminService.GetCustomerList<genType>(23);     return PartialView(clList); }   public IEnumerable<CustomerVM> GetCustomerList<S>(int clientId) where S : IEntityVMSortOrder{     ... }   Without changing the GetCustomerList function, how can I produce genType from the passed string argument? If this is possible at all.

What's the best way to call a generic method when the type parameter isn't known at compile time, but instead is obtained dynamically at runtime?  Consider the following sample code - inside the Example() method, what's the most concise way to invoke GenericMethod<T>() using the Type stored in the myType variable?  public class Sample {     public void Example(string typeName)     {         Type myType = FindType(typeName);          // What goes here to call GenericMethod<T>()?         GenericMethod<myType>(); // This doesn't work          // What changes to call StaticMethod<T>()?         Sample.StaticMethod<myType>(); // This also doesn't work     }      public void GenericMethod<T>()     {         // ...     }      public static void StaticMethod<T>()     {         //...     } }


The question is in the title. I have not found a counter example, so I try to prove it. However, contract diagonalization at the same time seems useless. Thanks very much.

I remember reading somewhere about the following properties of non-negative definite matrix. But I don't know how to prove it now.  Let $A$ and $B$ be two non-negative definite matrices. If $A^2\succ B^2$, then it necessarily follows that $A\succ B$, but $A\succ B$ doesn't necessarily leads to $A^2\succ B^2$.  How can you prove it? Thanks!


My attic has a ceiling light controlled by two 3 way switches connected with BX 14/3. Source and light wires were old knob & tube now replaced with Romex 14/2.  The duplex outlet is a new addition. The attached diagram is how I thought it could be wired. The duplex and switch 1 will be in one box. Romex 14/2 from source and light and BX will enter the box.   The diagram shows source connected to duplex. Then a short black wire runs from other duplex hot terminal, wire nutted to BX white wire with black tape, to common on switch 2. Load runs from common on switch 1 to light. I didn’t show ground wires to keep diagram simple, but everything will be grounded. The purpose of this layout was to minimize pigtails & wire nuts. Does this layout meet the NEC?  I posted this again because I couldn't find my original post so thought it didn't get posted. The only difference from the first post was the added sentence stating the purpose of the layout.  Thanks, henrylr

My attic has a ceiling light controlled by two 3 way switches connected with BX 14/3. Source and light wires were old knob & tube now replaced with Romex 14/2.  The duplex outlet is a new addition. The attached diagram is how I thought it could be wired. The duplex and switch 1 will be in one box. Romex 14/2 from source and light and BX will enter the box.   The diagram shows source connected to duplex. Then a short black wire runs from other duplex hot terminal, wire nutted to BX white wire with black tape, to common on switch 2. Load runs from common on switch 1 to light. I didn’t show ground wires to keep diagram simple, but everything will be grounded.  Does this layout meet the NEC?


Seems everybody knows  by ear, even its rhythm is very suggestive.  I wrote down a version in C Major, it look like this:    The Lilypond source is  \relative g' { \key c \major \time 2/4 c g8 g as4 g r b c }   I tried a web search with the note names and a Google image search with the above image, both resulted in nothing useful. From getting the source of this snippet, I hope to also get the information if this sequence is somehow copyrighted. Thanks for you help!

This rhythm pattern seems very famous and is oftenly used to knock on someone's door, sometimes as a code:    Does it have an history? Where does it come from?


As I understand, in English, when we are talking about something so close that we can (literally or figuratively) point our finger to, we can use "this".  This cake is great. (implies the participants are near the cake)  If we are talking about something that is not very close, or the place/time is not very specific, we can use "that".  That cake is great. (implies the cake is far away)  In my native language (Portuguese), a translation would be "isto" ("this") and "aquilo" ("that"). The problem is that there are many instances of English sentences using "that" that I would use "isto" in my native language instead. For example:  A: Let's eat some cake. B: That would be great.  I understand that translations may not perfectly capture the nuances of different languages. My question is if using "this" would be OK in that instance. More generally, is English more lax regarding the use "this" and "that" ("isto" and "aquilo" are very strict in Portuguese). P.S: my question is essentially the same one as , but the accepted answer does not really answers the issue of using both words interchangeably (I'm looking for a yes/no answer).

It is 10 cm on the map. That is 100 km in real terms.   I am proofreading and it seems odd that the writer always uses that in these cases. I would have said this.     Who is right and who is wrong?


I can't install any software on Ubuntu 18.04.  I'm facing some error like:   Unmet dependencies. Try 'apt --fix-broken install' with no packages   Output of sudo apt --fix-broken install:  Reading package lists... Done  Building dependency tree  Reading state information... Done  Correcting dependencies... failed.  The following packages have unmet dependencies:  dbconfig-mysql : Depends: default-mysql-client but it is not installed or virtual-mysql-client  E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.  E: Unable to correct dependencies   How can I solve this?

I just recently bought an arduino and requires gcc-avr/avrdude to compile the software. I installed avr for another microprocessor component a while ago but is obviously an outdated version (gcc version 3.3 20030512 (prerelease)) so I went ahead to update these but it didn't work.   (Please note that before hand I also broke my aptdaemon through an incomplete wine installation (couldn't get passed font installation agreement) but I fixed that via a re-installation then accepting the agreement.)   I am trying to update these by running  but the dependencies it requires cannot be installed due to avr... terminal reports   Reading package lists... Done Building dependency tree        Reading state information... Done build-essential is already the newest version. libncurses5-dev is already the newest version. libncurses5-dev set to manually installed. libusb-0.1-4 is already the newest version. libx11-dev is already the newest version. You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies: arduino-core : Depends: gcc-avr but it is not going to be installed avr-libc : Depends: gcc-avr (>= 1:4.3.4) but it is not going to be installed Depends: binutils-avr (>= 2.20) but it is not going to be installed binutils-dev : Depends: binutils (= 2.21.0.20110327-2ubuntu3) but 2.21.0.20110327-2ubuntu2 is to be installed libcwidget-dev : Depends: libcwidget3 (= 0.5.16-3ubuntu2) but it is not going to be installed Depends: libsigc++-2.0-dev but it is not going to be installed Depends: libncursesw5-dev but it is not going to be installed libmpfr-dev : Depends: libgmp3-dev (>= 4.2.dfsg-1) but it is not going to be installed python-dev : Depends: python (= 2.7.1-0ubuntu5.1) but 2.7.1-0ubuntu5 is to be installed Depends: python2.7-dev (>= 2.7.1-1~) but it is not going to be installed tk8.4-dev : Depends: tk8.4 (= 8.4.19-4) but it is not going to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).   But running   apt-get -f install   results in   (Reading database ... 163021 files and directories currently installed.) Unpacking binutils-avr (from .../binutils-avr_2.20.1-1ubuntu2_i386.deb) ... dpkg: error processing /var/cache/apt/archives/binutils-avr_2.20.1-1ubuntu2_i386.deb (--unpack): trying to overwrite '/usr/bin/avr-size', which is also in package avr-binutils 2.13.90.030512-2 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Unpacking gcc-avr (from .../gcc-avr_1%3a4.3.5-1_i386.deb) ... dpkg: error processing /var/cache/apt/archives/gcc-avr_1%3a4.3.5-1_i386.deb (--unpack): trying to overwrite '/usr/bin/avr-g++', which is also in package avr-gcc-c++ 3.2.90.20030512-2 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing: /var/cache/apt/archives/binutils-avr_2.20.1-1ubuntu2_i386.deb /var/cache/apt/archives/gcc-avr_1%3a4.3.5-1_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   I have tried running update manager and updating my system via it but all I get is an error message  The following packages have unmet dependencies: arduino-core: Depends: gcc-avr but it is not installed avr-libc: Depends: gcc-avr (>= 1:4.3.4) but it is not installed Depends: binutils-avr (>= 2.20) but it is not installed   which then tells me to try running apt-get -f install which just results the same as last time.  So how can I fix my system, I really need the new avr, please :) BTW, my system is Ubuntu 11.04


My question is about prepositions and what to use when talking about computer and software.   I will Install a software (in,on,into) my computer a software was installed (in,on,into) my computer

When I say "programs to install on a new PC" it sounds alright to me, but I'm not sure if it's the correct usage. Which one of the following should I use?   Programs to install on a new PC Programs to install in a new PC Programs to install to a new PC


I seem to have an odd issue with GIMP. Since two days, if I try to pick a color with the color picker, GIMP returns a wrong (and seemingly arbitrary) color. The color selection tool already looks broken:    If I now try to select the dark blue in the center of the image, the color it selects is completely wrong:    I have tried reinstalling GIMP, to little avail. I made sure the image is in RGB, and I reset the color management preferences. Any idea what causes the issue, and how to fix it? I am using GIMP 2.10.8 on Windows 10.  Edit: As requested, an image of the color picker tool options:

I'm new to Gimp and it seems the color picker does take a color brighter than it is supposed, i have to get the hexa color from another app using screenshot.  is there any settings that will make it work properly?


Let $X$ be a set, $P(X)$ the power set of $X$, and $2^X$ the set of all function from $X$ to $\{0, 1\}$.  Now define $J: P(X) \rightarrow 2^X$ by $J(A) = \chi_A$, where $\chi_A$ is the characteristic function.  Show that $J$ is a bijection from $P(X)$ to $2^X$.  I can demonstrate that $J$ is a bijection from $P(X)$ to $\{\chi_A | A \subset X\}$.  But how do I know for sure that $\{\chi_A | A \subset X\} = 2^X$?  Or, is there a function in $2^X$ that does not take the form of $\chi_A$?  I am not seeing how the answer is no, but I can't think of any counter examples either.

How can I formalize that the function $$f:\mathcal{P}(A)\to(A\to \{0,1\})$$ is bijective? It seems clear to me but I don't know how to write a proof. Thanks in advance.


What is the probabilty that there are no 2 people's in 12 people room with the same birthday month ?  I thought about $\frac{12!}{12^{12}}$,but , i think its wrong. What do you think ?  Thanks.

If there are $12$ people in the room what the chances are that no two people will have the same birthday month?   I tried to think of it in this way:  The total number of options is $12^{12}$  The option that no one will have the same birthday month is:  $12 * 11 * ... 1$ which means $12!$  So I think the answer is:  $$\frac{12!}{12^{12}}=0.0000537$$  What do you think?   Thank you!


Prove the following statement: $N_1N_2/(N_1\cap N_2)\cong (N_1N_2/N_1) \times (N_1N_2/N_2)$ where $N_1, N_2$ are normal subgroups of $G$  How do I approach this question? I tried using the first isomorphism theorem, but got stuck. Maybe I should use a different approach.

Suppose that $H$ and $K$ are normal subgroups of a group $G$ such that $HK=G$. I need to show that  $G/(H\cap K)\cong (G/H)\times (G/K)$.  So from the second isomorphism theorem we have that:  $HK/H\cong H/(H\cap K)$ which gives that $G/H\cong H/(H\cap K)$  $HK/K\cong K/(H\cap K)$ which gives that $G/K\cong K/(H\cap K)$  So we must now show that:  $H/(H\cap K)\times K/(H\cap K)\cong G/(H\cap K)$  So consider the map $\theta:H/(H\cap K)\times K/(H\cap K)\rightarrow G/(H\cap K)$ such that $\theta(h(H\cap K)\times k(H\cap K))=hk(H\cap K)$  Now this is a homomorphism and is surjective. To check injectiviy we see that if:  $\theta(h_1(H\cap K)\times k_1(H\cap K))=\theta(h_2(H\cap K)\times k_2(H\cap K))$ then we have that:  $(h_1k_1(H\cap K))=(h_2k_2(H\cap K))$ so that $(h_1k_1)(h_2k_2)^{-1}(H\cap K)=(H\cap K)$ which gives that $h_1k_1(H\cap K)=h_2k_2(H\cap K)$ So we are done.  Is the above correct?  Thanks for any help


Let there $K\leq G \times H$ Then $K$ is of the form $G'\times H'$ where $G'\leq G$ And $H'\leq H$  Intuitively the definition of $G\times H$ a cartesian product of two groups, so there can not be an element in it, which is not a product of two subgroups.  By contradiction , Let assume that there is $(k_1,k_2)\in (A\times B)$ and $(k_3,k_4)\in (C\times D)$ Where $A,B,C,D$ are not a subgroup of $G$ or $H$ and not of each other, then  $$(k_1,k_2)(k_3,k_4)=(k_1k_2,k_3k_4)\in K$$ but $k_1k_2\notin G$ and $k_3k_4\notin H$ contradiction   Is it correct?

This question arose in the context of :     Let $G$ and $G'$ be groups and $V$ a subgroup of $G\times G'$.   Do there exist subgroups $H \leq G$ and $H'\leq G'$ such that $V \cong H\times H'$?   In the case that the answer is "no": Are there any reasonable constraints to $G$ and $G'$ such that the answer is "yes"? For finite abelian groups, the answer appears to be yes.  Clarification  My question is about the subgroup $V$ being isomorphic to a direct product of subgroups. This condition is strictly weaker than being equal to a direct product of subgroups: For the "equal" version, the classical counterexample is the diagonal subgroup $V = \langle (1,1)\rangle \leq G\times G$ where $G$ may be any group but the trivial one. However, this doesn't provide a counterexample to my question, since $V\cong G\times\{1\}$.