var a=new Number(6);  var b=new Object(6); a===b;  //false   I just do not understand why a===b return false. It has same type and come from same instance.

I'm using  to go through JavaScript, and it's returning many suggestions to replace == (two equals signs) with === (three equals signs) when doing things like comparing idSele_UNVEHtype.value.length == 0 inside of an if statement.  Is there a performance benefit to replacing == with ===?   Any performance improvement would be welcomed as many comparison operators exist.  If no type conversion takes place, would there be a performance gain over ==?


When I read Hartshorne, I saw the Proposition 2.6 in Chapter III as follows:     Let $(X,\mathcal{O}_X)$ be a ringed space. Then the derived functors of the functor $\Gamma(X,-)$ from the category of $\mathcal{O}_X$-modules to the category of abelian groups coincide with the cohomology functors $H^{i}(X,-)$.     I am pretty confused here because I think it is just the definition of cohomology functor... Why should we bother to use the result about the flasque sheaf and acyclic resolution to prove this?   So I must miss something important and obvious. Please point it out. Thanks!

There is something very weird with the way Hartshorne defines right derived functors.     Hartshorne p 204 Let $\mathfrak A$ be an abelian category with enough injectives, and let $F \colon \mathfrak A \to \mathfrak B$ be a covariant left exact functor. Then we construct the right derived functors $R^iF, i ≥ 0$, of $F$ as follows. For each object $A$ of $\mathfrak A$, choose once and for all an injective resolution $I^.$ of $A$. Then we define $R^iF(A) = h^i(F(I^.))$   With Prop 1.2A. Hartshorne claims that one can also compute the right exact functor $R^iF$ with a resolution $J^i$ that is acyclic for F.  But then, in prop. 2.6 (and similarly in prop. 8.4) Hartshorne states what was already true by definition: that the derived functors of $\Gamma(X,^.)$ coincide with the cohomology functors $H^i(X,^.)$. The proof goes around a circle to show the obvious fact that an injective resolution is equivalent to itself. Namely, that every injective is flasque (2.4), and flasques are acyclic (2.5), so by 1.2A. (above) we can use this very injective resolution(!).  What do we need to go around like that?


Is it possible that the Milky Way and the local cluster or maybe the entire visible universe is inside the event horizon of a truly gigantic black hole that is so far away that we haven't noticed it or its effects?

Observations:   I have read that for a free-falling observer within the event horizon of a black hole that all lines of sight will end at the singularity which is black. I also look up and see that the sky is mostly black. I also know that by measuring the red-shifts of the galaxies that they are all accelelerating towards that blackness. (rather than accelerating away from a big-bang event, which makes less intuitive sense) The red-shifts are greatest for those galaxies closest to the singularity (i.e. furthest away from us).   I therefore conclude from these consistent observations that all the matter in at least the finite observable region of the universe in which we are located, is accelerating due to gravity towards the singularity of a super-massive black hole.  In the spirit of good science I will happy accept being wrong, but I need to understand why I am wrong.  Predictions from the theory:  The light from the universe outside the event horizon of the black hole should be visible as a small disc or point light source in the direction facing away from the singularity. Of course, if this happens to be inconveniently located on the far side of the milky way's core from us, then we will be unable to observe it.  Further Speculations:  It may be that in regions of the universe far ouside the influence of this black hole (e.g. >50 billon light years away) that the sky is white hot due to Olber's paradox.  The black hole may have been formed from a large quantity of anti-matter, which might explain the local perponderance of ordinary matter.  The microwave background radiation may be a result of Hawking radiation at the event horizon (which we are viewing fromn the inside), or, depending upon the non-euclidian geometry, we may be observing the result of matter being destroyed at the singularity.


I was looking at flights out of Baltimore (BWI) to different places; France, Spain, etc. then on one of the bundle sites, it showed the same flight out of Boston (BOS) for less than half the price.   From Baltimore to Paris one month from now is $1200 but from Boston, it's only $448.  I check Philadelphia and other local airports but none were close.  Why are flights out of Boston cheaper?

Based on the question , I got curious. Is there a guide or resource that describes how the price of a ticket is determined?  When you search you often see curious effects like cheaper tickets for a flight from A to B with a layover compared to a direct flight. This seems counter-intuitive from an outsider's perspective since you fly twice. Also one way tickets more expensive than 2 ways.  It can be a short set of rules. Something that helps someone to get started with finding good prices. I know these can be very complex and they probably change over time and over airline interests but there is probably a simplified set of rules that can be enunciated.


Just wanted to know why planetary orbits get to be elliptical? I'm not debating how stable these orbits are (obviously almost completely stable), but why don't planets revolve in the special ellipse known as a circle? Wouldn't the centrifugal/-pedal forces between the planet and Sun make the planet revolve around the Sun in a perfect circle? Is there a 'third force' that attracts planets at a specific point (a hypothetical reasoning for elliptical orbits)? I'm not trying to disprove Kepler over here, but I don't exactly get it.

Almost all of the orbits of planets and other celestial bodies are elliptical, not circular.   Is this due to  by other nearby massive bodies?  If this was the case a two body system should always have a circular orbit.  Is that true?


We know that given any continuous map $f : X \to Y$, there exists an induced homomorphism $f_* : \pi_1(X, x) \to \pi_1(Y, f(x))$. Is the converse true? That is, given any homomorphism $\phi: \pi_1(X, x) \to \pi_1(Y, y)$, is there a continuous map $f : X \to Y$ such that $\phi = f_*$ and $f(x) = y$? If not, are there conditions for $X$ and $Y$ for the converse to be true?

I am looking for some examples of closed, orientable 3-manifolds $M$ and $N$ and a homomorphism $\phi : \pi_1(M) \to \pi_1(N)$ such that $\phi$ is not induced by any continuous map $f : M \to N$.  Are there examples of this occurring for lens spaces?  I do not believe that this phenomenon can occur for maps between surfaces.


Okay so im making an adventure map and i have a command block that will say when someone has found mining supplies and then you will have to click where it says here to receive some of it. The thing is it just says like error on line 323 unterminated character or something. Also i cant type the command cuz i broke to block so here is a picture of the text

I've been at this for almost two hours and no one seems to have the same problem as I and I doubt this will be solved but I'll try anyway.  this is the code  /tellraw @p ["Would you like to teleport?",{"text":"Yes","color":"green","bold":"true","clickEvent":{"action":"run_command","value":"/tp @p ~ ~4 ~ "},"hoverEvent":{"action":"show_text","value":{"text":"Confirm"}},{"text":"No","color":"red","bold":"true","clickEvent":{"action":"run_command","value":"/tellraw @p{"text":"Come back when you want to teleport"}"}}}]   this part is fine  /tellraw @p ["Would you like to teleport?",{"text":"Yes","color":"green","bold":"true","clickEvent":{"action":"run_command","value":"/tp @p ~ ~4 ~ "},"hoverEvent":{"action":"show_text","value":{"text":"Confirm"}}   it's just when I add this  ,{"text":"No","color":"red","bold":"true","clickEvent":{"action":"run_command","value":"/tellraw @p{"text":"Come back when you want to teleport"}"}}}]   Minecraft gives me the error:     Invalid JSON at line 1 column 203   I've tried to space it out and figure out what column 203 is but I can't, I don't know what I did. Anyone got any ideas?


A table made containing the edit information field a problem to run code undifined code in function  please help me to fix this error  "info" id table in html   function submit () {     var table = document.getElementById("info");     var td1 = document.createElement("td")     var td2 = document.createElement("td");     var row = document.createElement("tr");      td1.innerHTML = document.getElementById("p-name").value;     td2.innerHTML = document.getElementById("p-id").value;      row.appendChild(td1);     row.appendChild(td2);     table.children[0].appendChild(row);   create button in script  var bedit = document.createElement("BUTTON"); var bename = document.createTextNode("Edit");  bedit.appendChild(bename); bedit.onclick = function () { edit_row(event) }  td6.appendChild(bedit);}   function code on click button in submit function  function edit_row() {     bedit.style.display = "none";     bsave.style.display = "block";      var input = document.createElement("INPUT");     input.setAttribute("type", "text");      var string = td1.textContent;      td1.innerHTML = "";     td1.appendChild(input);      input.value = string; }

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


I am new to physics and was trying to learn more especially about general relativity. The Schwarzschild metric, changes the sign of the time and radial parts of the metric once we cross the event horizon. Someone on stack exchange had noted that as a result inside the horizon the decrease in radius is the direction of increasing time.  My question is if radius (i.e space) becomes timelike due to change in metric sign, then does time also become spacelike. I mean can then inside the horizon one move freely in time?  NOTE: As far as my understanding of the linked question goes, that question is about cosmology of interiro of ablack hole (it asks about a spacetime originating form blackhole horizon). My question i think is different, its really more on the lines of time-travel.Since the signature of the time corrdinate is spacelike, it should behave like space and we should be able to move in it in the backward direction as we can in space. Some say that it is a coordinate artifact, but I think the other coordinates dont tend to have the physical interpretation of time.(I may have understood it incorrectly)

When solving the Einstein field equations in Schwarzschild metric for an observer falling into a black hole the radial coordinate r of the black hole and time t switch roles in the equations when r<2M.    If we transform into the resting coordinate system of an observer inside a black hole, the timelike geodesics will be along the radial dimension of the black hole. Would an observer inside the event horizon of a spherically symmetric black hole observer the radial dimension of the black hole as time? If yes, is it safe to assume that the laws of thermodynamics would hold inside the black hole, in which case the singularity of the black hole would as a zero entropy state be in the past along the radial "time" axis and the high entropy event horizon would be in the future along the same?  What would the cosmology of a spherically symmetric black hole look like from the perspective of an observer inside the black hole. It seems to me that from the perspective of an observer within the event horizon of the black hole:   The observable universe originates from a singularity (black hole singularity) The observable universe expands along the radial (time) dimension The exterior of the black hole is not observable from within the black hole There would be future boundary conditions defining the faith of the interior (event horizon) The interior in other than radial dimension would be relatively uniform for a static black hole   How does time behave inside a black hole from the perspective of an observer inside the black hole? Could such an observer see the interior of the black hole as a universe relatively similar to ours (assuming the arrow of time would be along the radial axis of the black hole).


I tried to solve this equation but without a success:  $3x^{2}+6x+1 \equiv 0 \pmod {19}$  I concluded hat $x(x+2)\equiv 6 \pmod{19}$, the only way i think to solve this is by just trying all the options. But there must be a more efficiant way.  I would like to get help with that, thanks

I need to solve $3x^2 + 6x +1 \equiv 0 \pmod {19}$  I saw the same problem here -     but didn't understand how he got to the conclusion   $x(x+2) \equiv 6 \pmod {19}$  and anyway im trying to solve it how we learned in class -   multiply both sides and the modulo by $4a$ then solve the two equations  $y^2 \equiv b^2 -4ac \pmod {4an}$  $2ax + b \equiv y \pmod {4an}$  so I tried multiplying the hole thing by $4a$ , that is $4 \times 3$  and got to $(2 \times 3x + 6)^2 \equiv 36 -4 \times 3 \pmod {19 \times 4 \times 3}$  now I am stuck . any help will be appreciated


I came across  in which a moderator noted that a user had a "same IP diff email". I was under the impression that our e-mail was  or used for the purposes explained in the input field help tip:    I also don't see where the  states that moderators have access to view it. [ It's in the first paragraph of the "How We Use Information We Collect" section. --Ed. ] If this is the case, I think users should know this and moderators have different tools to determine duplicate user accounts. Edit: it was mentioned in  and  that mod's have visibility, but it doesn't seem like it's very publicized. I'm finding this out after using the site after 3 years (perhaps I was a bit naive).

When editing my user profile (name, date of birth, etc.), how can I tell which information can be seen by other users (publicly visible) and what is only used by the system (and how it's used)?


I recently had my ESTA application approved. However on it I stated I would be staying in my friend's apartment only to discover my friend has relocated me and my girlfriend to a local hotel. Hence, my ESTA application says I'm staying at one location but I will be staying at another.  Will this be an issue?  Should I re-apply for a new ESTA?

I have an ESTA for my visit last Sept to NY and I know it is valid for 2years.  I am going to Las Vegas in May, do I have to update the address at which I will be staying?


Suppose $f$ and $g$ are entire functions,and $|f(z)|\leq|g(z)|$ for every z.What conclusion can you draw?  My conjecture : $f$ and $g$ are constant but I don't know how to deal with it.  I will appreciate your help

Suppose $f$ and $g$ are entire functions with $|f(z)|\leq|g(z)|$ for all $z$.  How can we show that $f=cg$ for some complex constant $c$?  Thanks for any help :)


Prove that for all natural numbers $k$, $k^5-k$ is a multiple of $10$.  I found several answers for this here, but none of which would have considered seperately the cases $\pmod{2}$ and $\pmod{5}.$ Since any integer $n \equiv 0,1 \pmod{2}$ we have that $k^5-k \equiv0 \pmod{2}$ thus divisible by $2$. However, the case $k^5-k \equiv0 \pmod{5}$ seems to be a bit trickier. Any integer $n \equiv 0,1,2,3,4 \pmod{5}$, but is this of any help as it seemed to be in the case of $\pmod{2}$?

I was wondering why the last digit of $n^5$ is that of $n$? What's the proof and logic behind the statement? I have no idea where to start. Can someone please provide a simple proof or some general ideas about how I can figure out the proof myself? Thanks.


If I try something like \u{i}, I get both the breve and the dot. How can I get it without the dot?


I'm using Clayton copula model to generate bivariate observations. x= poisson and y=gamma with, of course, certain dependence among them.  I have generated observations (X,Y) ~ f(x,y) using copula package in r but now I need to generate observation Y|X=x ~ f(Y|X=x) ¿Is there any way/algorithm to generate samples from conditional distribution that involves the copula? For example, like this, found in Nelsen:   Generate two independent uniform (0,1) variates u and t; Set v = cu(-1)(t), where cu(-1) denotes a quasi-inverse of cu . The desired pair is (u,v).         I have the next code in r where I model the observations according to Nelsen,using the quasi-inverse of cu from cCopula function:      t<-runif(1700)     u_t<-cbind(t,runif(1700))     V<-cCopula(u_t,claytonCopula(param=0.14,dim=2),inverse=TRUE)     x<-qpois(u_t[,1],lambda=d.poisson$estimate[1])     y<-qgamma(V[,2],shape=claim_size.gamma$estimate[1],rate=claim_size.gamma$estimate[2])     plot(data_sinout$d,data_sinout$claim_size,main='Test dataset x and y',col='blue')     points(x,y,col='red')   legend('topright', c('Observed', 'Simulated'), col = c('blue', 'red'), pch=21)   The result is:    which is quite reasonable being one of my first tries.  Now I want to generate observations of Y when X=15, it means f(Y|X=15), then according to the data I expect to have low values of y, in the range of [0,50k].So, I have this code:  t_x<-15 t<-ppois(t_x,lambda=d.poisson$estimate[1]) u_t<-cbind(t,runif(1700)) V<-cCopula(u_t,claytonCopula(param=0.14,dim=2),inverse=TRUE) x<-qpois(u_t[,1],lambda=d.poisson$estimate[1]) y<-qgamma(V[,2],shape=claim_size.gamma$estimate[1],rate=claim_size.gamma$estimate[2]) plot(data_sinout$d,data_sinout$claim_size,main='Test dataset x and y',col='blue') points(x,y,col='red') legend('topright', c('Observed', 'Simulated'), col = c('blue', 'red'), pch=21)   but instead I have:    which is not what I was expecting. Any help would be really appreciate it.

I am working in the bivariate case with copulas as follows:  I have two marginal Gamma distributions $f_1=Ga(\alpha_1, 1)$ and $f_2=Ga(\alpha_2, 1)$ that are bound by a copula Frank copula $C$, with parameter 10. Assume now, that I observe a value from $f_1=5$.   The question: How can I obtain a value for $f_2$, assuming that $f_1, f_2$ admit the copula $C$?   Initially I though it was a matter of conditinal probability with copulas as in , but I am not convinced about my approach. I tried with cCopula, but I am not sure I am on the right path. Any code sample would be highly appreciated.


Is there a term for a well informed person who is not believed, or not listened to, or is even ridiculed?  I do not necessarily mean some one before their time... I am thinking in more general terms.  (I have googled this but the question is too broad and has too many keywords and if I try to narrow it down I lose the original meaning.)

I'm trying to find either a word or a phrase that describes a person who knows the answer to a problem or problems but is never believed, even though the person is actually correct. The nearest I can come up with is maybe the story of , but that is about knowing the future but never being believed. The word or a phrase may indicate they are simply ignored, but I am more interested in answers indicating the person suffers negative consequences such as being ridiculed or even persecuted for their correct solution. Maybe think of people such as  I stumbled across  of people whose ideas were rejected and were treated as pariahs for them but were later proven to be correct. These are exactly the kind of people I am looking for words or phrases to describe.


Question is :  Let $G$ be a finite group and suppose the automorphism $T$ sends more than three quarters of elements of $G$ onto their inverses.  Prove that $T(x)=x^{-1}$ for all $x\in G$ and that $G$ is abelian.  What I could see is...  Once I prove $T(x)=x^{-1}$ for all $x\in G$ then I would have that $G$ is abelian.  Because, for any $a,b\in G$ we have   $b^{-1}a^{-1}=(ab)^{-1}=T(ab)=T(a)T(b)=a^{-1}b^{-1}$  Thus, $ab=ba$ for all $a,b\in G$ Thus $G$ is abelian.  So, Only problem is to prove that $T(x)=x^{-1}$ for all $x\in G$  I am unable to use the fact that      "$T$ sends more than three quarters of elements of $G$ onto their inverses"   May be I should take  : $A=\{x\in G : T(x)=x^{-1}\}$ and see if this is a subgroup (It is Not) or something like that.  Please help me to clear this.  I am very excited about this question So please do not spoil my excitement by posting full answer at once (This is a request cum order).  Please help me to do this by myself.   Thank you so much :)

Assume that $\pi$ is an automorphism of a finite group $G$. Let $S$ denote the set $\lbrace g \in G: \pi (g)=g^{-1} \rbrace$. Show that if $|S|>\frac{3|G|}{4}$, then $G$ is an abelian group.    Anyone has any idea on how to solve this ? I have no idea how to start.


I read this series around 9 years ago and honestly, I don't remember a thing about the plot. At any rate, I remember enjoying it. I'm not even certain that it was a trilogy, but it was definitely a series and all the books were published before 2006 thereabouts.  So what I do remember is that the main character was a girl and she had this slightly older mentor (male, and his name might have started with a 'C'). I have no idea what they did or if they had a quest (they probably did though) but I do remember that at one point she was trapped in a place or castle in a very cold, snowy environment. In fact, I'm fairly certain that the cover of the second (?) book was a very wintry one of the girl in said cold environment.  I also remember that at the end of the series, she didn't end up getting romantically involved with her mentor even though young me was desperately rooting for them. I was rather upset about that. It was also one of those fantasy series with an appendix of sorts at the back expanding on the world and briefly expanding on the background of the guy, if I'm not wrong. The appendix also talked about the girl and her various names, like a prophecy name or something.  There might also have been a tree involved somewhere, but I might be mixing that up so don't take my word for it about the tree. Anyway, I know this is about as vague as it possibly gets, but I'm giving it a try anyway!

I read a book quite a while back (probably quite a few years ago) that I downloaded (probably for free, but maybe not) on iBooks. I do not have iTunes anymore so I can't find it from there.   It was a fantasy book about a girl with magical ability. It was set in a different world to ours. Kind of medieval-esque? It starts with her in this keep, and she works there since her mother died. There are creepy guys there but she used her magic to hurt one and now they stay away. Then this man comes along, realises she can do magic, and takes her away and trains her. There is a big plot about saving the world I think. And there's a warm hot country where there is a man called something like Soluman.   That's all I can remember. If anyone knows or thinks they know what this is, could you please tell me? I know this is very vague, but it's all I can pin down. I'm pretty sure this was part of a trilogy or series of books. And I think it had a female author.


I have multiple small icons in a single file. They are separated with transparency. So I can manually select them and save individually. But this takes long time with many parts.  Is it possible to automatically save each non-transparent piece to separate file?

I have a sprite sheet from a classic video game (if you're curious, Final Fight) that I'd like to be broken up into indivual images to be used in . However, the images aren't on an even grid, and all have a different amount of space between them.  Is there an automated way to export images based on contiguous pixels or something like that?


As we know from coulomb's law that: $$\vec{E} = \frac{q}{4\pi\epsilon R^2} \hat{R}$$  using the above equation, how can I verify that: $$\vec{\nabla}\cdot \vec{E}=\frac{q}{\epsilon}$$  I have tried to do it a home, but couldn't figure it out. Explicitly showing all steps would be very much appreciated.

On a similar note: when using Gauss' Law, do you even begin with Coulomb's law, or does one take it as given that flux is the surface integral of the Electric field in the direction of the normal to the surface at a point?


I need a help to solve this question:  Let $u\in H^{1}_{0}(\Omega)$ with $u\geq 0$. Can I find a sequence of  smooth non-negative functions converging to $u$ in $H^{1}_{0}(\Omega)$?  Thank you in advance.

I want to prove the following fact :  Consider $\Omega \subset R^n$ a bounded and open set. Let $v \in H^{1}_{0}(\Omega)$ a nonnegative function. Then exists a sequence $v_m$ in $C^{\infty}_{0}(\Omega)$ of nongative functions converging to $v$ in $H^{1}( \Omega)$.  I know how to prove this fact (I think this fact can help): If $u_m$ is a sequence converging to $u$ in $H^1(\Omega)$ , then ${u^{+}_m} \rightarrow  u^+$.  Someone can give me a hint ?  Thanks in advance


After using my package manager to install VLC   apt-get install vlc   I get this message  root@DerPCmitDerGtx1050:/home/gtx1050# apt-get install  vlc 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:  vlc : Depends: libgles1-mesa (>= 7.8.1) but it is not going to be installed or             libgles1 E: Unable to correct problems, you have held broken packages.

From /var/log/dist-upgrade/apt.log:  Starting pkgProblemResolver with broken count: 1 Starting 2 pkgProblemResolver with broken count: 1 Investigating (0) libgles1-mesa [ amd64 ] < 12.0.6-0ubuntu0.16.04.1 > ( libs ) Broken libgles1-mesa:amd64 Depends on libglapi-mesa [ amd64 ] < 12.0.6-0ubuntu0.16.04.1 -> 17.0.7-0ubuntu0.16.04.1 > ( libs ) (= 12.0.6-0ubuntu0.16   .04.1)     Considering libglapi-mesa:amd64 64 as a solution to libgles1-mesa:amd64 2     Removing libgles1-mesa:amd64 rather than change libglapi-mesa:amd64 Investigating (0) vlc [ amd64 ] < 2.2.2+git20170721+r59033+56~ubuntu16.04.1 > ( video ) Broken vlc:amd64 Depends on libgles1-mesa [ amd64 ] < 12.0.6-0ubuntu0.16.04.1 > ( libs ) (>= 7.8.1)     Considering libgles1-mesa:amd64 2 as a solution to vlc:amd64 1 Broken vlc:amd64 Depends on libgles1 [ amd64 ] < none ->  > ( none )     Considering libgles1-mesa:amd64 2 as a solution to vlc:amd64 1     Or group remove for vlc:amd64 Done   Searching the web, I found that .  The VLC team have updated their dependencies from 2.2.2-5ubuntu0.16.04.2, but my system has apparently not caught up with that (I checked by running apt-cache depends vlc, and it shows a dependency on libgles1-mesa).  Now it happens that a couple of months ago I added the  (to get the latest, least buggy VLC).    That gave me VLC version 2.2.7 and fixed the VLC bug, and is what I have on my system today.  I know, because vlc --version tells me so.  apt-cache policy vlc says:  Installed: 2.2.2+git20170721+r59033+56~ubuntu16.04.1 Candidate: 2.2.2+git20170721+r59033+56~ubuntu16.04.1 Version table: *** 2.2.2+git20170721+r59033+56~ubuntu16.04.1 500     500 http://ppa.launchpad.net/videolan/stable-daily/ubuntu xenial/main amd64 Packages     100 /var/lib/dpkg/status  2.2.2-5ubuntu0.16.04.3 500     500 http://gb.archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages     500 http://security.ubuntu.com/ubuntu xenial-security/universe amd64 Packages  2.2.2-5 500     500 http://gb.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages   (It seems weird that apt-cache policy says that 2.2.2+git20170721+r59033+56~ubuntu16.04.1 is installed; I read that as vlc version 2.2.2, which conflicts with the 2.2.7 that vlc --version gives.)  Apparently I have Ubuntu version 16.04.2 LTS 64-bit installed (from System Details in the GUI Control Panel thing).  I suppose that I could disable the launchpad PPA, but in that case I would presumably revert to an older vlc binary which was crashing my system.  So my question is (at least I think this is the right question): How do I convince apt that it's ok that libgles1-mesa is old or missing?


I was trying to remove package with autoremove command & i got this error :            E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?"   how to resolve this?

I get this error whenever I try to install programs using the terminal:  home@ubuntu:~$ apt-get install myunity E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   Also I'm unable to install updates using the terminal.


I maintain a network of apx. 60-80 computers.  Normally I can remote desktop into these machines via a windows domain.  I'm for the most part self-taught however and I was wondering what is the typical method of remotely supporting an end user without logging them out of the machine?  A lot of the people on my network provide critical services (such as emergency call operations) or have user dependent applications which do not allow me to log them out and I need to be logged into them to configure them.  I've used and know of:   Ultra VNC TeamViewer LogMeIn Standard Windows Remote Desktop   Is there an option on Windows RDC that will allow this?  Or should I start installing Ultra VNC on the machines?  Thanks

Is it possible to use Windows remote desktop connection to connect to a Windows XP machine with a user already logged in and just view that users screen without logging them off?


Is there a proof that gives the evidence there is no closed form for $\int e^{-x^2} \cdot dx$?  or just because they were not able to find that elementry form for a long time of trying without any useful results then they told us that such a form does not exist?  Error function is solving the integral problem but it is not elementry function.  Applying the integral is simple by using Taylor series.  $e^{-x^2}=\sum_{n=0}^{\infty} \frac {(-1)^n x^{2n}}{n!} =1-x^2+ \frac {x^4}{2!}-\frac {x^6}{3!}+\frac {x^8}{4!}-...$  $\int e^{-x^2} \cdot dx =\sum_{n=0}^{\infty} \frac {(-1)^n x^{2n+1}}{n!(2n+1)} =x-\frac {x^3}{3}+ \frac {x^5}{2!5}-\frac {x^7}{3!7}+\frac {x^9}{4!9}-...$  And if there is no sufficient proof, I will be more confident that there is one and we should note that:  1) $\int_{-\infty}^{\infty} e^{-x^2} \cdot dx = \sqrt {\pi}$ which means the formula contains inverse trigonometric function/s.  2) $\arctan(x) =\sum_{n=0}^{\infty} \frac {(-1)^n x^{2n+1}}{(2n+1)} =x-\frac {x^3}{3}+ \frac {x^5}{5}-\frac {x^7}{7}+\frac {x^9}{9}-... $ it is similar somehow to $\int e^{-x^2} \cdot dx $ expantion series.  3) $\arctan(x)$ curve looks closely like error function curve.  4) Laplace proof (1812) ends with $I^2=2[\arctan(s)]_{0}^{\infty} =\pi$ , where $I=\int_{-\infty}^{\infty} e^{-x^2} \cdot dx$  And finally, the above 4 notes do not mean that $arctan(x)$ can give a solution, but with some intelligent handling using possible inverse trigonometric functions and other tools may lead to some useful results and that is what I believe if and only if there is no proof tells that no elementry function exists for $\int e^{-x^2} \cdot dx $

In the past, I've come across statements  along the lines of "function $f(x)$ has no closed form integral", which I assume means that there is no combination of the operations:  addition/subtraction multiplication/division raising to powers and roots trigonometric functions exponential functions logarithmic functions  which when differentiated gives the function $f(x)$. I've heard this said about the function $f(x) = x^x$, for example. What sort of techniques are used to prove statements like this? What is this branch of mathematics called?  Merged with "" by : Sometimes we are told that some functions like $\dfrac{\sin(x)}{x}$ don't have an indefinite integral, or that it can't be expressed in term of other simple functions. I wonder how we can prove that kind of assertion?


I am in phase of writing 2nd paper. Previous paper is rejected. The one of the main objection in previous paper was English quality. As English is not my native language and reviewers only say "there are some mistakes, paper quality needs to be improved". This puts me doubt in myself and my major concern becomes writing instead of doing research. I spend a lot of time to read my paper again and again and re-write sentences. But how do I know that it is good now. It is infinite loop for me. What should I do to enhance quality of English. I have nobody available to review my paper for me. Kindly give me some suggestions:   What about online proofreading software i.e. grammarly, language tool, perfectit etc? which one do you use especially for scientific writing form computer science domain? What about online copy-editors and proofreaders that are available to read my paper. I have checked some websites but the charges were too high. Do you have used any service like this that had affordable cost any other options?

As a non-native speaker of English, it can often be hard to spot some of the errors that a native speaker would find. For a long time, I've been thinking about getting a native speaker to help me with proof-reading my texts (articles, theses, application, etc), but I don't quite know where to look. What are some good ways to get proofreading for your texts?  For example, are there any websites on the Internet where one can exchange proofreading services between different languages? (Say, if you help me proofread my text in language x, I'll help you with yours in language y.)


I have recently accepted a postdoctoral position at a reputed institute in the UK. I am an oversees applicant, who will soon be moving to the UK to take on this role. During the interview, I did not enquire about relocation expenses, assuming there would be support for that, but I have now been told that postdocs in this institute don't get a relocation support. On top of this, new regulations on the UK visa mean that I am now having to pay almost 1200 GBP just to get a visa and permission to be in the UK.   The town I am moving to is quite expensive (almost London rates) and I am now having trouble raising money for the airfare and paying initial rent and deposit, let alone having money for food and miscellaneous expenses. I am in a very tight spot and don't know how to take the next steps. This role has come after a lot of difficulty, and this situation is making it very difficult. Any advice on what I could do ?

Do universities offer relocation assistance to a newly employed postdoc who comes from another country? Is it appropriate for the postdoc to ask for relocation assistance if it is not already offered?


I spend some weeks searching for potential answers for a similar problem without success. This happened after one of many MikTex updates I made but it is unclear to me the source of the problem. My yap.exe file has the date of 29 Oct'16, so this might give you some useful clue. I usually compile my documents to pdf and so I only use dvi and yap to do tests and quick debugging. In one such ocasion while opening the dvi with yap an error window open with the message "MiKTeX encountered an internal error." The report info is the following  MiKTeX Problem Report Message: MiKTeX encountered an internal error. Data:  Source: Libraries\MiKTeX\Core\Session\mfmodes.cpp Line: 50 MiKTeX: 2.9 OS: Windows 7 Professional, 64-bit, Service Pack 1, build 7601 Invokers: non-existing/explorer/TeXnicCenter SystemAdmin: yes PowerUser: no Root0: C:\Users\Myaccount\AppData\Roaming\MiKTeX\2.9 Root1: C:\Users\Myaccount\AppData\Local\MiKTeX\2.9 Root2: C:\ProgramData\MiKTeX\2.9 Root3: C:\Program Files (x86)\MiKTeX 2.9 UserInstall: C:\Users\Myaccount\AppData\Roaming\MiKTeX\2.9 UserConfig: C:\Users\Myaccount\AppData\Roaming\MiKTeX\2.9 UserData: C:\Users\Myaccount\AppData\Local\MiKTeX\2.9 CommonInstall: C:\Program Files (x86)\MiKTeX 2.9 CommonConfig: C:\ProgramData\MiKTeX\2.9 CommonData: C:\ProgramData\MiKTeX\2.9   The problem is the same regardless if I compile a document within TeXnicCenter or just try to open a dvi file directly from a directory or even if I just double-click on yap.exe. I guess there is no problem in compiling to a dvi document, just opening it.  Many thanks for your support

Since six weeks or two months YAP does not work for me anymore.  May be, Windows 10's update 1607 was performed then. But I'm not sure.  Message in "MiKTeX Problem Report" is "MiKTeX encountered an internal error.", Data-field is empty. Complete report below. This error occurs in both cases: when started from command line WITH and WITHOUT a -DVI-filename. It occurs as well, if started from "Start". MiKTeX-update was frequently done.  Any idea? I would appreciate it very much! I have to run dvipdfm now, to check my changes. That's VERY timeconsuming due to the 10,000 graphics included.  Many thanks in advance!  Regard Radler  MiKTeX Problem Report Message: MiKTeX encountered an internal error. Data:  Source: Libraries\MiKTeX\Core\Session\mfmodes.cpp Line: 50 MiKTeX: 2.9 OS: Windows 10 Pro, 64-bit, build 14393 Invokers: cmd SystemAdmin: no PowerUser: no Root0: C:\Users\Franz\AppData\Roaming\MiKTeX\2.9 Root1: C:\Users\Franz\AppData\Local\MiKTeX\2.9 Root2: C:\ProgramData\MiKTeX\2.9 Root3: C:\Program Files\MiKTeX 2.9 UserInstall: C:\Users\Franz\AppData\Roaming\MiKTeX\2.9 UserConfig: C:\Users\Franz\AppData\Roaming\MiKTeX\2.9 UserData: C:\Users\Franz\AppData\Local\MiKTeX\2.9 CommonInstall: C:\Program Files\MiKTeX 2.9 CommonConfig: C:\ProgramData\MiKTeX\2.9 CommonData: C:\ProgramData\MiKTeX\2.9


I had quite some problems with tlmgr and a faulty TeX Live installation on Linux but now, everything works okay, I guess. Anyhow, on my Mac I am using the package , which I want to install on my Linux machine as well. The  however tells me      If you accept scheme-full, and you still didn't get the material you were expecting [...] the package may not be available under a free software license, in which case it cannot be included in TeX Live.   Do I simply put the .sty-file to /usr/share/texmf-texlive/tex/latex/ or /usr/local/texlive/2014/texmf-dist/tex/latex/ ?

I know how to define a package or a class, but how do I make it available (to myself) at all times?  Say I have the package file commonstuff.sty (or myprettyclass.cls), that I want to be able to include in any .tex file I create on my computer. Where do I put it? Do I need to run some installer on it, or is it enough to keep it in a certain folder?  Note: I know I can just place it in the same folder as the .tex file, but that's not what I'm after here. I'm looking for a way to "install" the package centrally on my computer.


Can you give me a concrete example of two modules over a ring $R$ that are not isomorphic , but that are isomorphic as abelian groups.  I know that this question was posted here before, but the answer given was not a concrete example and I would like to see one.

I'm looking for an example of of two isomorphic abelian groups, which are not isomorphic $R$-modules for some ring $R$.   I suppose we can just the same abelian group $M$ twice, and use a different operation $R\times M \rightarrow M$ so the $R$ modules aren't isomorphic.  I can't think of such a group $M$ and ring $R$ to make this possible, though. Any ideas? Thanks.


I just did a test, and it seems like the below code will NOT find the following div
  integer = 1 $('.class-name#'+integer)    However, when the HTML code is changed to this:
, the following code will work:  integer = 1 $('.class-name#number-'+integer)    Just wondering then if ID has to start with a letter?

When creating the id attributes for HTML elements, what rules are there for the value?


I had a suggested duplicate on a site-meta post, and the yes/no banner came up.  I chose "no" and a popup came up recommending editing the post.  I did so, by clicking on the popup's edit button, and, on reopening my post, the banner is still there (no additional close votes were applied).  Why does it persist? I already answered no and made the appropriate edit.

I have  today and one member was voted as duplicate and private feedback was there, I choose no and submitted the form. When I revisit the question or refresh the page same notice reappears with yes/no options.  In-network tab I got 200 OK status and response as "success":true  Environment: OS: Windows 10 Browser: Chrome 79.0.3945.117 (Official Build) (64-bit)  From the comments, the same issue is happing with   (might be with whole StackExchange network)      From network tab


I exported a map and everything looks fine when viewing the PDF. But when printing it on my plotter, all the text disappears. The scale bar would bring but the text associated to the scale bar wouldn't. The title block also disappears. I've tried messing around with the settings. I've checked/unchecked "Embed All Document Fonts" and "Convert Marker Symbols to Polygons". I'm not sure what I'm doing wrong here. What's weird is I exported this map a few weeks ago and it printed just fine. Today, I needed to make a change to the map and exported it out, and now I am experiencing this issue. I must have changed one of the export settings in the past few weeks but I'm not sure what it is. Has anyone experienced this? Using ArcMap 10.6


I was wondering, when designing a class which is safely accessed by multiple threads, is using synchronized around object instance itself, a good practice?  public class Foo {     public synchronized void fun() {             } }   One of the side effect is that, when caller uses the class instance in the following way, it will blocks other threads from accessing foo.fun()  Caller tries to use the class instance as thread monitor  Foo foo = new Foo(); // This will have side effect, which blocks other threads from accessing foo.fun() synchronized(foo) { }     I was wondering, is using a private final Object instance as internal thread monitor in Foo class, a safer & better way?  public class Foo {     public void fun() {                 synchronized (monitor) {         }     }     private final Object monitor = new Object(); }

Whenever a question pops up on SO about Java synchronization, some people are very eager to point out that synchronized(this) should be avoided. Instead, they claim, a lock on a private reference is to be preferred.  Some of the given reasons are:    (very popular this one, also has an "accidentally" variant)     Other people, including me, argue that synchronized(this) is an idiom that is used a lot (also in Java libraries), is safe and well understood. It should not be avoided because you have a bug and you don't have a clue of what is going on in your multithreaded program. In other words: if it is applicable, then use it.  I am interested in seeing some real-world examples (no foobar stuff) where avoiding a lock on this is preferable when synchronized(this) would also do the job.  Therefore: should you always avoid synchronized(this) and replace it with a lock on a private reference?      Some further info (updated as answers are given):   we are talking about instance synchronization both implicit (synchronized methods) and explicit form of synchronized(this) are considered if you quote Bloch or other authorities on the subject, don't leave out the parts you don't like (e.g. Effective Java, item on Thread Safety: Typically it is the lock on the instance itself, but there are exceptions.) if you need granularity in your locking other than synchronized(this) provides, then synchronized(this) is not applicable so that's not the issue


I wanted to get a grounding in quantum mechanics, and was directed to the Feynman lectures. I was told to start from Vol I and work my way up to Vol III, where all the quantum mechanics stuff is. As a mathematician, I figured that the subject shouldn't be too difficult.  However, the books are far too broad, and full of stuff that was covered in my High School physics classes. I've also heard that the section on quantum mechanics doesn't really go into much depth.   My question is what should I read to gain a solid and deep understanding (as deep an understanding one can get without a physics degree) of quantum mechanics. Certain chapters of the Feynman lectures? A different book entirely?  Thanks

I'm really interested in quantum theory and would like to learn all that I can about it. I've followed a few tutorials and read a few books but none satisfied me completely. I'm looking for introductions for beginners which do not depend heavily on linear algebra or calculus, or which provide a soft introduction for the requisite mathematics as they go along.  What are good introductory guides to QM along these lines?


I am going through Concrete Mathematics and am having some difficulty understanding this particular spot in the chapter which introduces the Josephus problem.  Hopefully someone can clarify.  So let's suppose that we have 2n people originally. After the 1rst go around, we're left with   **image showing just the odd members left.**  and 3 will be the next to go. This is just like starting out with n people, except that each person's number has been doubled and decreased by 1. That is,        J(2n) = 2J(n) - 1 ; for n >= 1. We can now go quickly to large n. For example, we know that J(10) = 5, so         J(20) = 2J(10) - 1 = 2·5 - 1 = 9 :   Here is what I do not understand:    Similarly J(40) = 17, and we can deduce that J(5·2^m) = 2^(m+1) + 1.   How did we deduce J(5·2^m) = 2^(m+1) + 1.?  It seems to pop out of nowhere to me.

I've been going through  and have a question on the inductive proof for the . Recurrent relation:  $J(1) = 1$ $J(2n) = 2J(n) - 1$ $J(2n+1) = 2J(n) + 1$  Closed form hypothesis:  $J(2^m + l) = 2l + 1$, for $m \ge 0$ and $0\le l<2^m$  Inductive Proof (for the even case):  $J(1)=1$ $J(2^m+l)= 2J(2^{m-1}+l/2)-1=2(2l/2+1)-1=2l+1$  How do the authors get from $2J(2^{m-1}+l/2)-1$ to $2(2l/2+1)-1$?


I am looking to make a capacitor/UPS system for a few different electrical components in my car. I want to power the rear view camera, headrest monitors, and possibly the head unit for about 30 seconds after their individual power has been isolated. That way they will all stay on when the power supply is changed, for example when the car is turned over. Not sure where to start or anything really about capacitors. I can get the current draw for all the components, but dont know what Diode/Capacitors to buy and wire in.

Ok here's the problem. I have a power antenna in my car. The antenna goes up when a voltage is supplied to the voltage sensor in the antenna and goes down when the voltage is removed. I used this fact to install a switch allowing me to listen to CD's without deploying the antenna.   The problem is: Whenever I start the car when the radio is on, the voltage drop is enough so the sensor registers a loss of signal and begins to withdraw the antenna into the car only to redeploy three seconds later when the car is running and the voltage returns to normal. This is hell on the gears and the torque switch. My plan is to install a capacitor in the signal circuit so that the voltage sensor no longer registers a temporary loss of signal when the car is started but will still withdraw the antenna (after a bleed time ) when the car is off or the switch is turned off.   Two questions: Since I need about a 10 second bleed time how big a cap do I need? And  I install the cap in parallel across the signal leads, correct?  \$Update\$  Got it done tested, soldered, boxed and installed it works great!!!  Thanks to  @Davetweed AND @RedGrittybrick for your help and insight.


saaaaaa But when I paste the same content with the Git header prepended in , I get 996DF2EBC2E14AF3D19B0D5EB791A09F8318353B

As I understand it when Git assigns a SHA1 hash to a file this SHA1 is unique to the file based on its contents.   As a result if a file moves from one repository to another the SHA1 for the file remains the same as its contents have not changed.   How does Git calculate the SHA1 digest? Does it do it on the full uncompressed file contents?   I would like to emulate assigning SHA1's outside of Git.


I have to be prove the following inequality, where $z_1$ and $z_2$ are two complex numbers. $$|z_1 + z_2| \le |z_1| + |z_2|$$  I know I can substitute Z as 'x + iy' and open both sides but I am confused about the inequality. Any help would be appreciated.

I was wondering how to prove the triangle inequality with complex numbers:  Verify that the function $d(z_1, z_2)$ is a distance funtion on $\mathbb{C}$ and also on any subdomain on $\mathbb{C}$.  I finished all but the inequality, which is what I need assistance with. I don't know how to prove the distance function inequality:  $d(z_1, z_3) \le d(z_1, z_2) + d(z_2, z_3) $


I am managing a few computers and there is a program on them that must be run as an admin to work. There are multiple standard users and one admin user (me) on the computers. Is there a way to set only that program to run as an administrator without needing to enter in admin credentials every time on a standard account?

My goal is to for a limited used to be able to run a netsh script that requires administrative privileges:  netsh wlan stop hostednetwork netsh wlan start hostednetwork   From my administrative account I created a task scheduler task that runs this script with elevated privileges and saved my admin password in it. It worked. But the task is not visible from the limited user account.  I tried creating the same task from the limited user task scheduler - did not happen, it told me the user has no rights to create the task.  Tried schtasks.exe from the limited user, it also does not show the task I want to run.  Is there a way to share the task I created from the administrative account with a limited user so he is able to run it on demand? Or give him privileges to create the task himself?


Here i am trying to copy a file from a source location to the target location. from shutil import copy2 sourcefile = "file.avro" targetdirectory = "/home" copy2(soucefil,targetdirectory)  But i need to copy the file to the new location with a different name say file.avro.copy Is there any python library that can be used for renaming file while copying itself. Donot want to copy and rename in two different steps.

How do I copy a file in Python?  I couldn't find anything under .


I have a question:  Let $F$ and $K$ fields such that $F\subset K$. Can we conclude that $1_K=1_F$?  I found any counterexaples when $F$ and $k$ are rings, but not necessarily fields. However when these are fields I don't get conclude nothing...

If $R$ is an integral domain and a subring $S$ has identity $1_S$, how would you show that $1_S=1_R$ (here $1_R$ is the identity of the ring $R$)? I am unsure about what an integral domain really is and how the subring comes into play here.


I have been struggling a lot with a NullPointerException on a class method. The problem is that when I call variables that are initialized on the constructor, they return null. Remember that the KitGUI extends GUI.  package src.foundation.core.game.kit;  import org.bukkit.entity.Player;  import src.foundation.core.GUI; import src.foundation.core.game.Game; import src.foundation.core.game.Kit; import src.foundation.core.util.ItemStackFactory;  public class KitGUI extends GUI {     private Game game;     private Player player;      public KitGUI(Game game, Player player)     {         super(player, "Select Kit", 27);         this.game = game;         this.player = player;     }      public void addItems()     {         for (Kit kit : this.game.getKits())         {             // NullPointerException...             addMenuItem(ItemStackFactory.createItem(kit.getDisplay()));         }     }      public void checkItems()     {         for (Kit kit : game.getKits())         {             if (getClick().getItemMeta().getDisplayName().contains(kit.getName()))             {                 game.selectKit(getPlayer(), kit);                 break;             }         }     } }   And the GUI class:  package src.foundation.core;  import org.bukkit.Bukkit; import org.bukkit.Sound; import org.bukkit.entity.Player; import org.bukkit.event.EventHandler; import org.bukkit.event.inventory.InventoryClickEvent; import org.bukkit.event.inventory.InventoryInteractEvent; import org.bukkit.inventory.Inventory; import org.bukkit.inventory.ItemStack;  public abstract class GUI extends Module {     private String name;     private int slots;      private Inventory inventory;      private Player player;     private ItemStack choice;      public GUI(Player player, String name, int slots)     {         super("GUI");          this.name = name;         this.slots = slots;         this.player = player;          this.inventory = Bukkit.createInventory(null, this.slots, this.name);          addItems();          this.player.openInventory(inventory);     }      public abstract void addItems();      public abstract void checkItems();      public void addMenuItem(ItemStack item)     {         this.inventory.addItem(item);     }      public Inventory getInventory()     {         return this.inventory;     }      public ItemStack getClick()     {         return this.choice;     }      public Player getPlayer()     {         return this.player;     }      @EventHandler     public void selectChoice(InventoryClickEvent e)     {         this.player = (Player) e.getWhoClicked();         this.choice = e.getCursor();          e.setCancelled(true);          if (!(e.getInventory().getName().equals(this.name)))             return;          if (e.getCurrentItem() == null || !e.getCurrentItem().hasItemMeta() || !e.getCurrentItem().getItemMeta().hasDisplayName())             return;          if (e.getCursor().getItemMeta() == null)             return;          if (e.isCancelled() == true)         {             checkItems();              this.player.playSound(this.player.getLocation(), Sound.CHICKEN_EGG_POP, 1.0F, 1.0F);              this.player.closeInventory();         }     } }   Stack Trace:  Caused by: java.lang.NullPointerException         at src.foundation.core.game.kit.KitGUI.addItems(KitGUI.java:25) ~[?:?]         at src.foundation.core.GUI.<init>(GUI.java:32) ~[?:?]         at src.foundation.core.game.kit.KitGUI.<init>(KitGUI.java:18) ~[?:?]         at src.foundation.core.game.GameManager.lobbyItemsUse(GameManager.java:2 68) ~[?:?]   Any ideas on where the problem might be? Regards.

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


I have difficulty interpreting some results. I am doing an hierarhical related regression with ecoreg. If I enter the code I receive output with oddsratio's, confidence ratio's and a 2x maximized log likelihood.   However, I do not fully understand how to interpreted the 2x maximized log likelihood. As far as I know log likelihood is used as a convenient way to calculate a likelihood and it calculates the value of the parameters based on the outcomes. But I do not understand if a higher or lower value is better. I looked at several online sources e.g. , but I am still stuck.   Below the outcome I receive:  Call: eco(formula = cbind(y, N) ~ deprivation + meanIncome, binary = ~fracSmoke +      soclass, data = dfAggPlus, cross = cross)  Aggregate-level odds ratios:                     OR        l95        u95 (Intercept) 0.0510475 0.03837276 0.06790878 deprivation 0.9859936 0.88421991 1.09948134 meanIncome  1.0689951 0.95574925 1.19565924  Individual-level odds ratios:                 OR       l95      u95 fracSmoke 3.124053 2.0761956 4.700765 soclass   1.001050 0.9930815 1.009083  -2 x log-likelihood:  237.4882   So, how should I interpreted a value of 237.4882 compared to an outcome of 206 or 1083? Help is much appreciated!

I have difficulty interpreting some results. I am doing an hierarchical related regression with ecoreg. If I enter the code I receive output with odds ratios, confidence ratios and a 2x maximized log likelihood.   However, I do not fully understand how to interpret the 2x maximized log likelihood. As far as I know log likelihood is used as a convenient way of calculating a likelihood and it calculates the value of the parameters based on the outcomes. But I do not understand if a higher or lower value is better. I looked at several online sources e.g. , but I am still stuck.   Below the outcome I receive:  Call: eco(formula = cbind(y, N) ~ deprivation + meanIncome, binary = ~fracSmoke +      soclass, data = dfAggPlus, cross = cross)  Aggregate-level odds ratios:                     OR        l95        u95 (Intercept) 0.0510475 0.03837276 0.06790878 deprivation 0.9859936 0.88421991 1.09948134 meanIncome  1.0689951 0.95574925 1.19565924  Individual-level odds ratios:                 OR       l95      u95 fracSmoke 3.124053 2.0761956 4.700765 soclass   1.001050 0.9930815 1.009083  -2 x log-likelihood:  237.4882    So, how should I interpreted a value of 237.4882 compared to an outcome of 206 or 1083? Help is much appreciated!


I'm working on a wizard and have an issue about the flow illustration. I wan't to help the user as much as possible and think it would be confusing to make a flow with 6 steps where the last 3 is optional, - therefor i have the issue explained below:       The wizard have to include :   select columns Add filters  Select if you wan't to "View" "Export to Excel" or "Save" the report   If view:  Shows the report in the application  If Export to Excel: Opens an Excel document with the data   If saving:     3.a add name and discribtion      3.b Add excel template     3.c Maybe add subscribtions  How can i present the flow for users when Step 3. determines whether the remaining steps are shown?  How can i make a layout that shows where in the flow users are when you do not know how far they want to go?  Is there another way of doing it?

I'm toying with the jQuery plugin  to implement a branching wizard for a web application. The problem I'm struggling with right now is how to deal with user choices that affect the subsequent workflow and the content and re-ordering of the progress meter of the wizard.  As for now I can think of 3 alternatives.   Static solution: Lay out all possible steps in advance. Though some steps will only be activated if the user makes the appropriate choice. Otherwise, the wizard continues with the next valid step. As an example: If someone doesn't need the "flight transfer option" the wizard simply leaves out all steps concerned with that choice. Fluid solution: Lay out only the default or required steps (happy path scenario). If for instance at some point the user chooses to branch away from the visible path (I need the transfer option) the wizard gets a visual update and also its progress meter. Now, showing all the additional steps. (I'm not sure though if this is visually appealing.) A combination of 1 and 2: This is meant as an extension to 1) and 2) where all the choices are made up-front like in a short enquiry (1st step). Based upon these choices the wizard gets a visual update with the corresponding workflow. If the user wants to change the choice she made she has to re-visit the first step (which creates the potential complexity of not loosing already entered data)


I had Ubuntu 12.04 installed with Wubi on a partition of my main HDD and decided I would do a proper installation of it. In the process of prepping the drive, I foolishly formatted the partition before uninstalling Ubuntu and because of that, the entry on the Windows boot manager menu was never removed either.  How might I go about fixing this problem? I'm hoping to be able to remove that entry and disable the menu.  Cheers

I installed ubuntu using Wubi side by side with Windows. I decided to uninstall ubuntu and install Kubuntu, which I did successfully. However now when I boot my computer, the Windows Boot Manager displays 3 options:   Windows Ubuntu Kubuntu    The Ubuntu option does not work, but the entry did not get removed when I uninstalled  Ubuntu the first time. How do i get rid of this extra entry?


I think the five people were killed in the aircraft from this . The headline is:     Melbourne plane crash: Five killed as aircraft hits shopping centre   Why use active voice rather than passive voice in this news headline?   Is the auxiliary verb dropped in this sentence? Is the full sentence "Five have been killed as aircraft his shopping centre"?

Newspaper/news article headlines usually have different syntax rules, for example   No copula. North Korea trip 'successful' Past events written in present. Qantas cancels flight out of frozen Heathrow Predictions written with infinitive. Britain's 'crossbow cannibal' to die in jail Very often not in complete sentence. No indefinite/definite articles. Ivory Coast Faction Squeezes UN Force Using a comma instead of "and". Romania, Bulgaria face delay in joining Schengen.   Why these rules and are there any other rules?


A Quick Note  I know there is a slough of related questions on stack exchange, but none of them really seem to answer my question. This  is the closest in relationship to my question, but the answer simply expresses a high level mathematical explanation, and not an example I can teach my kids. Growing up, my school always taught that division by zero was undefined or not allowed, but never really explained why, or how this was true.  The  has a very good answer, that I understand, however I'm not so sure my kids would understand that answer. The accepted answer will have to be understood by children under age 10 with a minimal working knowledge of multiplication and division.    Getting Started  The other day, I was working on a project at home in which I performed division by zero with a double precision floating point number in my code. This isn't always undefined in the computer world and can sometimes result in $\infty$. The reason for this is clearly explained in  and quite thoroughly in :     Division by zero (an operation on finite operands gives an exact infinite result, e.g., $\frac{1}{0}$ or $\log{0}$) (returns ±$\infty$ by default).   Now, this got me thinking about basic arithmetic and how to prove each operation, and I created a mental inconsistency between multiplication and division.    Multiplication  As this is an important part of the thought process that lead me down this mental rabbit hole, I am including the elementary explanation of multiplication.   If I place $10$ marbles on my desk, $3$ times, I have placed $30$ marbles on my desk.   This is expressed as $10 \cdot 3 = 30$ and is true.  If I place $10$ marbles on my desk, $0$ times, I have placed $0$ marbles on my desk.   This is expressed as $10 \cdot 0 = 0$ and is true.    These two scenarios are true no matter what numbers are used.    Division  This is where things took an unexpected turn in my mind.  Let's say that I am a wandering saint and I have 50 apples. I want to help the hungry people of the world so I give my apples away freely. Now, let's handle two similar scenarios.   I come across $10$ people, and I want to give them all of my apples, I also want to ensure that each person receives the same number of apples. With $50$ apples to disperse across $10$ people, this means each person receives $5$ apples.   This is expressed as $\frac{50}{10} = 5$ and is true.    However, let's say I have the same $50$ apples, and I come across a town where no one is hungry, and no one wants my apples. Well, I have $50$ apples, and I have $0$ people to give them to, so I still have $50$ apples. I didn't disperse my apples evenly across any number of people, so it's still the same bag of $50$ apples.  I believe this may be my mind's way of bending the facts here, and that I've convinced myself that I'm dividing $50$ zero times, but in fact I may have divided $50$ one time (by me). But it has me thinking, if I divide a pizza into zero equal slices, well then I essentially didn't slice the pizza and thus still just have an entire pizza.    My Question  How can it be proved thoroughly, not just with math, but with an example explanation (understandable by children) that division by zero is truly undefined?

We consider following equation a×0=0 in this equation we able to multiply by zero.  but why not divided by zero? when multiplication and division are just inverse process.


hi so i am new to c# and i had a problem while i was trying to solve a little riddle: i need to find how many a-s are in a certain string.     int anum = 0;     string a = Console.ReadLine();     for(int i = 0; i < a.Length; i++)     {         if (a[i] == "a")         {             anum++;         }     }     Console.WriteLine(anum);  while i was solving it there was an error that i couldn't fix: '==' cannot be applied to operands of type 'char' and 'string' i tried googling it but it didnt help please help

I am doing something where I realised I wanted to count how many /s I could find in a string, and then it struck me, that there were several ways to do it, but couldn't decide on what the best (or easiest) was.  At the moment I'm going with something like:  string source = "/once/upon/a/time/"; int count = source.Length - source.Replace("/", "").Length;   But I don't like it at all, any takers?  I don't really want to dig out RegEx for this, do I?  I know my string is going to have the term I'm searching for, so you can assume that...  Of course for strings where length > 1,  string haystack = "/once/upon/a/time"; string needle = "/"; int needleCount = ( haystack.Length - haystack.Replace(needle,"").Length ) / needle.Length;


I was following a tutorial about cameras and lightning. At certain point the shortcut Ctrl Alt Numpad 0 was introduced. This shortcut was about moving the camera to the point I was looking at.   The strange thing is that the camera did not moved to that point, but every time I switch to camera view mode with Numpad 0. It goes to that point. Even when I remove all cameras from the scene, that point is the camera view.   Bellow is a print screen showing the view point when I click on Numpad 0. You can see that the camera is somewhere else.   Can someone tell me what am I looking through when I click on Numpad 0 if there is no camera set at that point. Also if I have no camera on the scene, why is Numpad 0 even working.  References:  Tutorial Link:

Trying to follow along with a tutorial and in that tutorial the idea is to look at an object I created from the front and then set the camera to the current view.  The steps to do this are:   Numpad 1 (Front perspective) Ctrl+Alt+Numpad 0 (Align Camera to View)   For some reason whenever I do this I don't see anything in the camera and then panning the view around I see that my object seems to have moved to where I wanted the camera and my camera hasn't moved at all.


Why salesforce does not support Roll-up Summary on Account for Contact as it is only supporting one standard object which is Opportunity ?  I have checked for Roll-up Summary (  ) and salesforce says that its mandatory to have Master-Detail relationship between objects then only you can have Roll-up Summary field on parent object.  According to above, how is Roll-up Summary on Account is supported for Opportunity object ?  Please check these screenshots:

On Opportunity there is a lookup relationship to Account.But why it behaves as Master-Detail as we can create Rollup Summary Fields on Account.  Similarly if we delete Account then Contact gets deleted but there is lookup relationship between Contact and Account  What is the relationship between Opportunity/Account and Contact/Account ? (Lookup or Master-Detail)


I'm trying to generate some code at runtime where I put in some boiler-plate stuff and the user is allowed to enter the actual working code.  My boiler-plate code looks something like this:  using System;  public class ClassName {     public double TheFunction(double input)     {         // user entered code here     } }   Ideally, I think I want to use string.Format to insert the user code and create a unique class name, but I get an exception on the format string unless it looks like this:  string formatString = @" using System;  public class ClassName {0}     public double TheFunction(double input)     {0}         {2}     {1} {1}";   Then I call string.Format like this:  string entireClass = string.Format(formatString, "{", "}", userInput);   This is fine and I can deal with the ugliness of using {0} and {1} in the format string in place of my curly braces except that now my user input cannot use curly braces either.  Is there a way to either escape the curly braces in my format string, or a good way to turn the curly braces in the user code into {0}'s and {1}'s?  BTW, I know that this kind of thing is a security problem waiting to happen, but this is a Windows Forms app that's for internal use on systems that are not connected to the net so the risk is acceptable in this situation.

How can brackets be escaped in using string.Format? For example: String val = "1,2,3" String.Format(" foo {{0}}", val);  This example doesn't throw an exception, but it outputs the string foo {0}. Is there a way to escape the brackets?


How can I show that each smooth conic in $\Bbb P _2\Bbb C $ is  isomorph to the conic given by the equation $x^2+y^2+z^2=0$? I thought about considering the quadratic form $A$ associated to my conic, A is symmetric so I can say that $D=P^{-1}AP$ where D is diagonal with coefficients $d_1, d_2, d_3$. Know I probably have to define a maps from $\Bbb P _2\Bbb C $ to $\Bbb P _2\Bbb C $ using $P$, but I can't understand which is the correct way to do that! Can anyone help me? Thanks in advance!

I've got to show that any irreducible conic in $\mathbb{P^2(\mathbb{K})}$ where $\mathbb{K}$ is algebraically closed is isomorphic as a quasiprojective variety to the projective line. I wrote the conic as equivalent to the zero locus of $ x^2 +y^2+z^2$ in $\mathbb{P^2(\mathbb{K})}$. I tried to use the standard affine charts to cover this simpler variety and parametrize it but i didn't manage to do that. What am i missing?


I am writing a program that dose many math computations that eventually make a list of points to plot.  I does so over several iterations and gets one point per iteration, and then uses the new point for the next iteration in the code.  The list conditions_old holds the values from the last iteration.  The list conditions_new are the new points that are found after an iteration is finished.  At the end of the code, the lists are set equal to each other: conditions_old = conditions_new.  This is the only time conditions_old is assigned a value except for the initial conditions that are used to start the calculations.  With all that said, here is the problem I'm having:  conditions_old = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]  kCompute = conditions_old[:]  for i in range(3):     for j in range(3):         print("conditions_old BEFORE: ", conditions_old[i][j])         kCompute[i][j] = (conditions_old[i][j] + (1/4))  # This is where things get fishy.         print("conditions_old AFTER: ", conditions_old[i][j])         print("kCompute: ", kCompute[i][j])   This is a small portion of my code.  What happens is that the list conditions_old will acquire the values of kCompute once that calculation has been made.  My question is this; why is conditions_old acquiring the the new value of kCompute?  Also, how do you fix this problem?  I've  seen python do some odd things before, but this is something I never expected to run into.  I'm currently using python 3.4 on Yosemite

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


This might have some duplicated inquiry that   had, and while I think I have some of  about it, I would like to ask the community here for more opinions.  So referring to  or , one might still beg the question: Why is the speed of light 299792458 m/s? Don't just say "because it's defined that way by definition of the metre." Before it was defined, it was measured against the then-current definition of the metre. Why is $c$ in the ballpark of $10^8$ m/s and not in the order of $10^4$ or $10^{12}$ m/s?  A similar questions can be asked of $G$ and $\hbar$ and $\epsilon_0$.  To clarify a little regarding $c$: I recognize that the reason that $c\approx10^9$ m/s is that a meter is, by no accident of history, about as big as we are and a second represents a measure of how fast we think (i.e. we don't notice the flashes of black between frames of a movie and we can get pretty bored in a minute).  So light appears pretty fast to us because it moves about $10^9$ lengths about as big as us in the time it takes to think a thought.  So the reason that $c\approx10^9$ m/s is that there are about $10^{35}$ Planck lengths across a being like us ($10^{25}$ Planck lengths across an atom $10^5$ atoms across a biological cell and $10^5$ biological cells across a being like us). Why? And there are about $10^{44}$ Planck times in the time it takes us to think something. Why?  Answer those two questions, and I think we have an answer for why $c\approx 10^9$ in anthropometric units.  The other two questions referred do not address this question.  gets closest to the issue (regarding $c$), but he does not answer it. I think in the previous EDIT and in the comments, I made it (the question) pretty clear. I was not asking so much about the exact values which can be attributed to historical accident. But there's a reason that $c \approx 10^9$ m/s, not $10^4$ or $10^{12}$.  Reworded, I suppose the question could be "Why are the anthropometric units (which are about as big as we are) as large as they are relative to their corresponding Planck units?" (which is asking a question about dimensionless values). If we answer those questions, we have an answer for not just why $c$ is what it is, but also why $\hbar$ or $G$ are what they are.

Meaning, why is it the exact number that it is? Why not 2x10^8 m/s instead of 3? Does it have something to do with the mass, size or behavior of a photon? To be clear, I'm not asking "how we determined the speed of light". I know there isn't a clear answer, I'm really looking for the prevailing theories.


Is it possible to cultivate Hops in Dehradun District of Uttarakhand, if affirmative, from where I can procure Rhizomes/seeds in India?

I want to grow hops in Rajasthan (India).  How do I get seeds for hops in India?  Are there any companies in India that can provide me with what's necessary to grow my own?


I have a frequent problem at home - I try to connect to an audio device from my phone and fail, because the moment I turn it on my computer connects to it. So I have to go to the computer and manually disconnect the device. Is there a way to tell windows not to reconnect automatically to Bluetooth audio devices?

My laptop (running Win10) repeatedly "steals" the bluetooth connection for my headphones while they're connected to my phone. The only way I've been able to prevent the headphones' connection from switching to the laptop is to play some media or make a phone call immediately after reconnecting to my phone, or to unpair the headphones from the laptop.  The headphones are Plantronics Backbeat Go 2, and the specifications from the Plantronics product page give the following information for the Bluetooth entry:      Bluetooth v2.1:   A2DP 1.2, AVRCP, HFP v1.5, HSP v1.1   Thanks in advance!


I have a query handler decorator which logs any exceptions:  public class QueryHandlerLogDecorator<TQuery, TResult> : IQueryHandler<TQuery, TResult>     where TQuery : IQuery<TResult> {     private readonly IQueryHandler<TQuery, TResult> _handler;     private readonly ILog _log;      public QueryHandlerLogDecorator(IQueryHandler<TQuery, TResult> handler)     {        _handler = handler;        _log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);     }      public TResult Handle(TQuery query)     {         try         {              var result = _handler.Handle(query);              _log.Info("Ok");              return result;         }         catch (Exception ex)         {             _log.Error(ex.Message, ex);                              throw new Exception(ex.Message);         }     } }   Whilst the exception handling isn't the worst thing in the world, what it means is that I lose the type of the exception being thrown.  For example, if I throw ApplicationException lower down in the application, this is caught and rethrown as Exception.  How can I rethrow the exception being caught as the original type?

What are the best practices to consider when catching exceptions and re-throwing them? I want to make sure that the Exception object's InnerException and stack trace are preserved. Is there a difference between the following code blocks in the way they handle this?  try {     //some code } catch (Exception ex) {     throw ex; }   Vs:  try {     //some code } catch {     throw; }


Yesterday I've successfully installed Ubuntu 12.04 (x64), but something's bothering me, what about the drivers of my motherboard? I have the support DVD with the drivers of my motherboard, but I don't know where to start.  My motherboard is Rampage 3 Extreme.  Thank you for the responses...

Perhaps it's a silly question but I've recently purchased a new motherboard and of course it came with a CD with it's drivers only for Windows systems (you know, the Autorun cr@p and all that)  So, should I somehow try to obtain these drivers from the vendor for my Linux system or is that not necessary since the OS installation will take care of it by itself?


Lets say I have this table name "Stuff"  ╔════╦═════╗ ║ ID ║ VAL ║ ╠════╬═════╣ ║  1 ║ A   ║ ║  2 ║ B   ║ ║  3 ║ C   ║ ║  4 ║ C   ║ ║  5 ║ C   ║ ║  6 ║ D   ║ ║  7 ║ B   ║ ║  8 ║ E   ║ ╚════╩═════╝   I would like a query which can give me an output of where in the numbers the letters are repeating. Feel free to use any column name for the table.  Basically I want something that says "C" is reapeating on number 3, 4, and 5. "B" is repeating on number 2, and 7.   On my work I have thousand of rows. The example I gave you is very granular. If you need more information please let me know.

Consider a database table holding names, with three rows:  Peter Paul Mary   Is there an easy way to turn this into a single string of Peter, Paul, Mary?


How do I grant access to inner properties of objects in the right way? This is what does break my application:  I have an object that handles an array (simplified here):  function ListManager() {     var list = [],         add = function (element) {             list.push(element);         },         clear = function () {             list = [];         };      return {         add: add,         clear: clear,         list : list     }; };   But I get this when using it:  var manager = new ListManager(); manager.add("something"); manager.clear(); console.log(manager.list.length); // <= outputs "1"!   Stepping through the code shows, that within the clear method, list becomes a new array. But from outside the ListManager the list ist not cleared.  What am I doing wrong?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


My requirement is to replace the html tags in the string.   I have tried using Jsoup and other parsers . I tried with regular expressions .   But the problem is they are removing content which is not html also.  Example:
hi Hello
Second Hi Hello If BB &amp; this is true After body in message body normal text.   Expected output:  hi Hello Second Hi Hello If BB  this is true After body in message body normal text   Actual output:  hi Hello Second Hi Hello If BB  this is true After body in message body normal text   Could someone let me know the possible approaches?

Is there a good way to remove HTML from a Java string? A simple regex like replaceAll("\\<.*?>", "")   will work, but things like &amp; wont be converted correctly and non-HTML between the two angle brackets will be removed (i.e. the .*? in the regex will disappear).


I like to learn things even outside my university degree and I wonder if it is moral to read articles found online on blogs and other sources?

When I am at home and looking for journal articles I often find article PDFs  through google that have been uploaded to various websites (e.g., universities, institutions, arbitrary websites, etc...).   I am worried that using these files may infringe copyright since these articles may be bought by these universities (for example) and (by mistake?) were freely uploaded to their domain name like: www.university.edu.lb/journal_article1.pdf (probably for their own students?).   Is it ethical to use these downloaded PDFs during my research without going back to my own university elibrary to use them? When, if ever, would I be breaching copyright or breaching professional ethics if I accessed these files?   EDIT: my question also covers books as, sometimes, these are entirely available on some sites (whether they are institutional sites or not).


I want to update to 2.8, and it looks like I just have to download that version. Will i have to delete my old version or will it automatically replace it?

Haven't used blender for a while. Do I still have to delete my current blender and download new one from the webiste?


This morning I logged into my Stack Overflow account and then it displayed my account reputation like this:        But after some time I lost 16 reputation (see below). Why? I don't know.

My reputation rating on SO took this hit an hour ago, and it is due to what appears to be the simultaneous deletion of multiple questions.  I am uncertain why it happened, am concerned, and would appreciate an explanation.  Going to  shows that it was removed due to moderation.  Was a script run deliberately, or were we hit with a question deletion attack; what happened?  -12     today -2  1 hour ago  removed     How to send a 2d Vector over UDP in c++ -2  1 hour ago  removed     How do I use the Eclipse debugger to debug a Java application? -2  1 hour ago  removed     PHP string error; inconsistency with local and server -2  1 hour ago  removed     Unable to start the MySQL service after a server migration -2  1 hour ago  removed     How to use Java to print a text file on a ticket printer? -2  1 hour ago  removed     How can all of the ZBrush Obj files be imported to make a complete model?


I have a Canon 7D.  Suddenly my camera says "Card cannot be accessed. Reinsert/change the card or format card with camera".  This is a card I have been using for about 6 months.  How can I retrieve the photos on the card?  This is the second time this has happened with my 7D.  What am I doing wrong?

I know this is not specifically a photography issue but since many of us with prosumer/professional-level DLSRs use Compact Flash cards, it is bound to happen to others as well.  I have a Sandisk 16GB Ultra card that occasionally had the camera reporting inability to access the card. I had to reinsert the card to continue using it. I was able to read the card and transfer the photo files to my computer drive. Today, the same thing happened again, just that nearing the capacity of the card, it failed one last time and the camera was subsequently unable to read it anymore. Despite reinsertion.  My other CF cards never once exhibited this problem, so it's pretty much isolated to this card.  The card is similarly unrecognisable on my computer CF card reader. I think the filesystem is toast, but I suspect the photo files are still intact. I would like to find ways where I can inspect the raw binary data in the card and hopefully recover the photos?


I'm exploding on "." to get file format and name:  list($txt, $ext) = explode(".", $name);   The problem is that some files have names with dots.  How do I explote on the LAST "." so that I get $name=pic.n2 and $ext=jpg from: pic.n2.jpg?

This is a question you can read everywhere on the web with various answers:  $ext = end(explode('.', $filename)); $ext = substr(strrchr($filename, '.'), 1); $ext = substr($filename, strrpos($filename, '.') + 1); $ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $filename);  $exts = split("[/\\.]", $filename); $n    = count($exts)-1; $ext  = $exts[$n];   etc.  However, there is always "the best way" and it should be on Stack Overflow.


It is known in multivariate calculus that, at a critical point $p_c = (x_{1c}, x_{2c}, ... , x_{nc})$ of the function $f(x_1, x_2, ... , x_n)$, if the Hessian is positive definite we have a local minimum and if it is negative definite we have a local maximum.  However, I'm curious about the eigenvectors of the Hessian.  Do they represent anything useful?  For instance, do they represent an ellipsoid inside of which $f(p_c)$ is the global maximum/minimum?

Say $f \in C^2$ so we can possibly use its Hessian $H$ to determine whether $f$ has a local max, min, or saddle at a critical point $x_0$. Since $H(x_0)$ is real and symmetric, it is diagonalizable, say with eigenvector-eigenvalue pairs $(v_1,\lambda_1),\ldots,(v_n,\lambda_n)$. The second derivative test asserts that if all the $\lambda_i$ are strictly positive, then $f$ has a local min, if they are all strictly negative, then $f$ has a local max, and if there are at least one strictly positive and one strictly negative, then $f$ has a saddle point.  Is there some geometric interpretation to what the $v_i$ are? Are the $v_i$ somehow directions in which the function restricted to that direction has concavity $\lambda_i$?


I have the following problem:  Prove that if $k > 1$, then $$\dfrac{1}{(k - 1)^2} - \dfrac{1}{(k + 1)^2} = \dfrac{4k}{(k^2 - 1)^2}$$ Hence simplify $$\sum\limits_{k = 2}^n \dfrac{k}{(k^2 - 1)^2}$$  My Work: $$\dfrac{1}{(k - 1)^2} - \dfrac{1}{(k + 1)^2} = \dfrac{(k + 1)^2 - (k - 1)^2}{(k - 1)^2 (k + 1)^2} = \dfrac{(k + 1)^2 - (k - 1)^2}{(k^2 - 2k + 1)(k^2 + 2k + 1)}$$ I could have continued and multiplied the denominator out, but, at this point, I'm thinking that I'm actually expected to have proceeded differently, rather than multiplying the denominator out fully? And I don't have solutions for this problem, so I can't check anything. I would appreciate it if someone could please take the time to explain this problem.


Where can I find or enable the processing toolbox in QGIS 2.18? Doesn't seem to be an option in the "View" drop menu, and the help file doesn't have anything about how to get it to display  I attached a screenshot of what QGIS looks like to me, maybe it's there somewhere and I'm missing it?

I'm sure there is a really simple explanation to this but haven't found any pointers on this forum or elsewhere. I seem to have lost the 'processing' menu from QGIS and can't figure out how/why!? Any ideas what I might have done to make this happen?  I'm running QGIS 2.8 built against GDAL 1.10 on Ubuntu 14.04.


I have this:A piece of ice is gently placed on the surface of water filled in glass tumbler, so the water rises to the brim. What will happen to the level of water when the ice melts?  I still don't get it why the level of water remains the same. I tried to find out from other sources but they proved it using fancy physics formulas which I don't have and know currently. Please, can anyone give me a hand in this?

I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a clear equation explanation that would be great.


I have a point layer in QGIS that has a field named "Amount" that stores an integer value for every point in the layer.   I want to create N points in the exact place of the feature that has N as value in the amount "field". I mean, if a point has in the amount field 16, I need to create 15 more points in that exact lat long (1+15 so that there are 16 in total) of that point.   After this process, the sum of "Amount" values in the starting layer should be equal to the sum of points in the new layer.  I need it to create a heatmap with the new layer. What is the easyest way of achiving this?  Regards

I have a set of data as polygons, each with a Number field with value X. Is there then a way to copy this into X number of polys at the same location? (ideally points distributed across the poly but that's a bonus).  In QGIS I have tried Random Points, but this doesn't inherit attributes, and Join Attributes by Location is useless if the parent polys overlap.  The reason behind this is for collating data easily with the GroupStats plugin.


As I known all the matter consists of atoms. What is the simplest possible experiment (with as little scientific equipment as possible) that can prove that there are atoms?

Which experiments prove atomic theory?  Sub-atomic theories:   atoms have: nuclei; electrons; protons; and neutrons. That the number of electrons atoms have determines their relationship with other atoms.   That the atom is the smallest elemental unit of matter - that we can't continue to divide atoms into anything smaller and have them retain the characteristics of the parent element. That everything is made of atoms.     These sub-theories might spur more thoughts of individual experiments that prove individual sub-atomic theories (my guess is more was able to be proven after more experiments followed).


In Real analysis from Folland, we define $|v|$ when $v << u$ for some positive measure $u$, $dv = f du$ for some $f$ in $L^1$, $d|v| = |f|du$. But in page 99, folland's book, the proof of thm 3.22 says that "IT IS EASILY VERIFIED THAT $d|v| = d|p| + |f|dm"$. Hmm... I can't find definition of $d|v|$ when $dv = dp + fdm$. What is this?

Two simple exercises on complex measures I don't know how to solve, from Folland's Real Analysis. I find it difficult to manipulate the definitions in computations. For context, if $\nu$ is a complex measure on $(X,\mathcal{M})$ then $|\nu|$ is defined as $d|\nu|=|g|\,d\mu$ where positive measure $\mu$ and $g\in L^1(\mu)$ are such that $\nu \ll \mu$ and $\nu = g\,d\mu$ (and in the textbook it's shown that this definition does not depend on the choice of $\mu$).     1) Let $\nu$ be a reguar complex Borel measure on $\mathbb{R}^n$, $m$ denote   Lebesgue measure, and   let $d\nu = d\lambda + f\,dm$ be its Lebesgue-Radon-Nikodym   representation. Then ("it is easily verified")   $d|\nu|=d|\lambda|+|f|\,dm$.      2) If $f\in L^1(\nu)$ then $f\in L^1(|\nu|)$. I was able to prove the   reverse implication, but not this one.   The definition of $|\nu|$ in the case of real signed measures (as $|\nu|=\nu^+ + \nu^-$) makes sense to me but I can't see intuitively into the definion of $|\nu|$ for complex measures as given in the textbook. Do you have any advice on this?  Thank you!


I'm confused on how to apply the law of total probability when the summation is $\sum_{0}^{1}$ i.e. from 0 to 1, including all possible decimal numbers in between, rather than a summation of $\sum_{a}^{b}$ where a and b are integers. Is the following the correct approach (using an integral from 0 to 1)?  If I apply the law of total probability to P(Y=1), does it equal:  $ \int_{0}^{1} $P(Y=1|X=x)P(X=x)dx  where Y $\in$ {0,1} and x$\in$[0,1]

If we have a probability space $(\Omega,\mathcal{F},P)$ and $\Omega$ is partitioned into pairwise disjoint subsets $A_{i}$, with $i\in\mathbb{N}$, then the  says that $P(B)=\sum_{i=1}^{n}P(B|A_{i})P(A_i{})$. This law can be proved using the following two facts: \begin{align*} P(B|A_{i})&=\frac{P(B\cap A_{i})}{P(A_{i})}\\ P\left(\bigcup_{i\in \mathbb{N}} S_{i}\right)&=\sum_{i\in\mathbb{N}}P(S_{i}) \end{align*} Where the $S_{i}$'s are a pairwise disjoint and a $\textit{countable}$ family of events in $\mathcal{F}$. However, if we want to apply the law of total probability on a continuous random variable $X$ with density $f$, we have (): $$P(A)=\int_{-\infty}^{\infty}P(A|X=x)f(x)dx$$ which is the law of total probabillity but with the summation replaced with an integral, and $P(A_{i})$ replaced with $f(x)dx$. The problem is that we are conditioning on an $\textit{uncountable}$ family. Is there any proof of this statement (if true)?


While working in intelliJ I was recommended to make a method be localized - by removing the access modifier. I realized I don't really know which modifier to use and when and would like some clarification.  I read this post:   and as that's for C#, although they're similar, I wanted to make sure it's not too different.  I also read the Javadoc post here:   and was still a bit skeptical.  Thanks in advanced!

In Java, are there clear rules on when to use each of access modifiers, namely the default (package private), public, protected and private, while making class and interface and dealing with inheritance?


We run a 20+site WPMU, and have ~16 super admins.  Today we made a new admin and before we could even talk to her, she updated the site to 3.8, which we weren't on yet due to lots of silly bureaucratic reasons. I am personally grateful she updated, but we can't let this happen again.  Is it possible to turn off the ability for site admins to update and throw a global function on the site that only allows specific users to upgrade?  The only idea I have so far is to hide the update bar in the CSS and show it for the specific users.

update_core     update_plugins     update_themes     install_plugins     install_themes     delete_themes     edit_plugins     edit_themes   Hi, I want to restrict those capabilities to user_id = 1 so other super admins cant edit network files. (Btw if i am missing something, let me know). What is proper way of this? Tried  but it adds 'manage_esa_options' cap to every blog so super_admins see tons of blogs in their admin bar..


What is the Python code to create a password encrypted zip file?  I'm fine with using some apt-get'able utilities using system on the command line.

I am creating an ZIP file with ZipFile in Python 2.5, it works ok so far:  import zipfile, os  locfile = "test.txt" loczip = os.path.splitext (locfile)[0] + ".zip" zip = zipfile.ZipFile (loczip, "w") zip.write (locfile) zip.close()   but I couldn't find how to encrypt the files in the ZIP file. I could use system and call PKZIP -s, but I suppose there must be a more "Pythonic" way.  I'm looking for an open source solution.


So I know that $\mathbb{R}$ is both open and closed. But given a set, $X\subset \mathbb{R}$, $X\ne \emptyset $ that is both open and closed, how does one show that $X=\mathbb{R}$?    Here is my attempt: Using the definitions I was given, $X$ open implies that for every $x\in X$ there is a $\delta \gt 0$, $(x-\delta,~ x+\delta)\subset X$.    Also, since $X$ is closed , $B=\mathbb{R}$\  $X$ is open.    However, I don't know how to proceed. NB: This is not a homework problem.

In other words, are $\emptyset$ and $\mathbb{R}$ the only open and closed sets in $\mathbb{R}$? Why/Why not?  I tried by assuming a set is equal to its interior points and contains its limit points.  A bounded set will not do since stuff like $[1,4]$ and $\{5\}$ will not work, though that is not really proof. Help please?  Anyway, it must then be unbounded.  If $a$ is a real number then $(a,\infty)$, $(-\infty,a)$, $[a,\infty)$ and $(-\infty,a]$ don't seem to cut it so it must be $\mathbb{R}$.


How can I determine which architecture (x86 or x64) my Ubuntu installation medium is for?  I don't have it installed, I just need to know which files on the installation media I can use to determine the architecture.

I installed some version of Ubuntu on my VMware, but I don't know what version exactly it is. How can I find it out?


It's well established that H(K||M) is vulnerable to length extension attacks for SHA-2 and other hashing algorithms, and instead an HMAC construction should be used. However - why can't H(M||K) be used instead? Will this also be vulnerable to length extension attack in the same way?

Consider a common practically-collision-resistant hash function $\mathcal{H}$ (e.g. , , , ), perhaps based on the  as are the first three. We define a  $\mathcal{C}$ $$(k,m) \mapsto \mathcal{C}(k,m)=\mathcal{H}(m\mathbin\|k)$$ where $\mathbin\|$ denotes concatenation, $k$ is a secret key (constant, or at least of fixed size), and $m$ is a message (possibly of variable length). Assume that an adversary can (iteratively) submit queries with $m_j$ and obtain $C(k,m_j)$, and wants to obtain $k$ or otherwise compute $C(k,m)$ for some $m\ne m_j$.  That MAC $\mathcal{C}$ is not trivially bad. In particular, if $\mathcal{H}$ was indistinguishable from a random function in the , $\mathcal{C}$ would be secure. And even though $\mathcal{H}$ may have the , it does not turn into a devastating attack on $\mathcal{C}$.  The less impractical generic attack that I see is that if a collision was known for $\mathcal{H}$ with the colliding messages of moderate identical length, it could be deduced countless collisions for $\mathcal{C}$. Hence security is demonstrably not better than collision-resistance of $\mathcal{H}$ (for identical-length messages). We could assume that $k$ is half the size of the result of $\mathcal{H}$, and hope that the security is about  or  or , 280, 2128, 2256 hash rounds for SHA-1, RIPEMD-160, SHA-256, SHA-512.   What are the known attacks against $\mathcal{C}$ (better than the above), and their cost, for each of these common hashes?  Is there hope for an argument that an attack against $\mathcal{C}$ would turn into an attack of similar cost against $\mathcal{H}$, or hint of the contrary?  Update: this  is of interest, but I fail to find that it really answers the present question.  Update 2: I am aware that the construction considered is weaker than , and in particular is vulnerable to collision on $\mathcal H$; I stated that, and that it is thus pointless to have the key wider hopeless to target security against some attacks better than half the hash's size. I'm asking exactly what cryptanalytic attack better than finding a collision on $\mathcal H$ there are. There is room for such an attack only by exploiting a weakness in the structure or/and the round function of a concrete $\mathcal H$.