I'm searching for to code for a empty y-axis label. I don't want numbers on my y-axis. Any Ideas?   My code:  \begin{tikzpicture}         \begin{axis}[only marks, width=1.02\textwidth,height=0.2\textheight,         legend style={at={(1,1)},xshift=-13.25cm, yshift=-0.1cm,anchor=north west,nodes=left},              xtick={1700, 1725, 1750, 1775, 1800, 1825, 1850, 1875, 1900, 1925, 1950, 1975}, %=Intervals             x tick label style={/pgf/number format/1000 sep=},              y tick label style={/pgf/number format/1000 sep=},             %extra y ticks={456.1, 1022.4},             %extra y tick labels={{456,1},{1022,4}},             extra y tick style={grid=major,                 tick label style={, ,}},                 ymin=0.7,                 ymax=1.4,             ylabel={Phänomenbelege},             enlarge x limits=0.01]                \addplot  table [x=jahr, y=bla] {bla.txt};             \addplot  table [x=jahr, y=blub] {blub.txt};                         \legend{bla, blub}  \end{axis}     \end{tikzpicture}

I've just started to play with pgfplot. I'm trying to prepare a plot like to following   \begin{figure}[h] \centering \begin{tikzpicture} \begin{axis}[minor tick num=1,  axis x line=middle, axis y line=middle, xlabel=$k$, ylabel=$\omega$, ymin=0,xmin=-2,ymax=60] \addplot[blue,domain=0:5, line width=1.5pt] {x^2+25}; \addplot[orange,domain=0:5,line width=1pt]{3*x+22.75}; \addplot[cyan,domain=0:1.5, line width=1pt,dashed]{18.166*x}; \node[coordinate,pin=right:{$v_{\phi}=\frac{\omega}{k}$}]     at (axis cs:1,17) {}; \node[coordinate,pin=right:{$v_{g}=\frac{d\omega}{dk}$}]     at (axis cs:2.5,30) {}; \node[coordinate,pin=left:{dispersion relation}]     at (axis cs:4.5,47) {}; \end{axis} \end{tikzpicture} \caption{Wave dispersion relation with phase and group velocity} \label{fig:2} \end{figure}   What I would like to do is dropping the x-y tick labels so that we just maintaing the x-y title. How can I obtain it?


I successfully included \usepackage[section]{placeins}, which positions my figures just before bibliography in a very nice way, but there is another problem. The first page of my paper which contained title, abstract and some introduction, now only has title and everything is flashed at the second page. How can i fix that? If i remove \usepackage[section]{placeins} then the first page problem does not appear, but there are the figure between bibliography in the end.

I have 5 tables and a section after them. After creation of an output file I have two tables on one page, then a section and last 3 tables on next page.  What I want to achieve is to put tables and section below them.  \begin{table}[ht]\footnotesize \centering \begin{tabular}{|ll|} ...... \end{tabular} \label{tab:result} \end{table}  \section{Section below tables}


I failed to use on-click functions in javascript. How can I add fade-in class on-click event? If possible modern javascript use or es6. Also, how can I remove the class in 5 seconds? Please suggest me no JQuery.  If possible all click event method function use.  I failed to use on-click functions in javascript. How can I add fade-in class on-click event? If possible modern javascript use or es6.Also, how can I remove the class in 5 seconds? Please suggest me no JQuery, please. if possible all click event method function use.      <!DOCTYPE html>                                <meta charset="utf-8">             <title>css layout</title>
                 <button onclick="animations()">Click Me</button>

I have an element that already has a class: <div class="someclass">     <img ... id="image1" name="image1" /> </div>  Now, I want to create a JavaScript function that will add a class to the div (not replace, but add). How can I do that?


How to calculate this limit:  $$\lim_{x\rightarrow 0}\left(\frac{1}{x}-\frac{1}{\sin x}\right)$$  All I know is:   $$\lim_{x\rightarrow 0} \frac{\sin x}{x} = 1$$  $$\lim_{x\rightarrow 0} \, x = 0$$  $$\lim_{x\rightarrow 0} \,\sin x = 0$$

Find the limit:   $$\lim_{x \rightarrow 0}\left(\frac1x - \frac1{\sin x}\right)$$  I am not able to find it because I don't know how to prove or disprove $0$ is the answer.


I've got directory with files like:  dump_2014_12_21_1001.7z dump_2014_12_21_1122.7z dump_2014_12_21_1207.7z dump_2014_12_21_1334.7z   Number of files may be different.  I need to write bash script to delete all files except newest one?

Is there a simple way, in a pretty standard UNIX environment with bash, to run a command to delete all but the most recent X files from a directory?  To give a bit more of a concrete example, imagine some cron job writing out a file (say, a log file or a tar-ed up backup) to a directory every hour. I'd like a way to have another cron job running which would remove the oldest files in that directory until there are less than, say, 5.  And just to be clear, there's only one file present, it should never be deleted.


Js doesn't work after using the ajax request, so I inject the script after each request, is it okay that way, if not, is there a better way?   createTable() {         function newTable() {             beelatter.ajax("GET", "./new_table.html", true, false, function () {                 if (this.readyState == 4 && this.status == 200) {                     beelatter.nodes().children[1].innerHTML = this.responseText;                                          //I need a better solution just for that.                     let script = document.createElement('script');                     script.src = "js/build.js";                     document.body.append(script)                 }             });          }         this.queryS(".new_group").addEventListener("click", newTable, true)     },

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


I have mobile Internet at home with one Huawei B593 4g-router. When it works it's pretty fast, around 17 Mbits/s down, but the service is unstable and I would frankly like it even faster. If i get one more internetsubscription so that I have two routers, each with its own simcard and subscription, would it be possible to connect them in a way that I got double download-speed and redundancy (if one malfunctioned the other would still be working). I would be willing to build a new computer to get this to work so just tell me what i would need. Thanks in advance.  Andy

I have two internet connection, each with 4mbps bandwidth. I want to join/merge both of them to get 8mbps speed, both routers have WLAN and LAN capability.    How to Double my speed using two routers? Can I bond two connections in Windows and double my internet connection speed? Any download manager that accepts two internet connection to download?


From time to time, SSH sessions to my servers just freeze up and then neither Ctrl+C nor Ctrl+\ do anything.  How do I quit the session without just closing the Terminal it's in?    Clarification:  The session is locked as in, no keys are transmitted to the server. I'd like to shut it down gracefully, such that the user isn't logged in anymore.  I know I can kill the SSH client, but that will, in time, make the "2 users" info message I get from uptime meaningless. I'd like to know how many users are really logged in.

I frequently ssh into my box at home from school, but usually when I change classes and my computer suspends, the pipe will be broken. However, ssh simply locks up - Ctrl+c, Ctrl+z and Ctrl+d have no effect.   It's annoying to have to restart my terminal, and even more annoying to have to close and re-create a new screen window.  So my question, is there an easy way to make ssh die properly (i.e. when the pipe fails "normally" it will exit with a message about a broken pipe)? Or do I have to figure out what the PID is and manually kill it?


If someone asks a question and does not look at any comments or answers that come up, how should I treat such people? Also he or she still logged in.

I have a situation where different users have asked questions and I answered them. The problem is not that they haven't accepted the answer which can tell me that it is correct or not. But they are actually not responsive and it seems to me that answer is being ignored. Or they asked the question just for the sake of asking.  See -the user was last seen yesterday, the same day it was answered.  -the user was last seen today.   which is also upvoted by a fellow user, but the OP is seen till days after it was answered and is not even commenting.  I went through a lot of question on meta on similar situation such as  where Anna says that it is completely voluntary for users to accept it.   But then again, I believe it is becoming a fashion, to ask a question read the answer as a suggestion and leave it.  It is discouraging me. I am not saying that my answers or suggestions are 100 percent working but I atleast need be told so I can improve it. And more importantly I am not the only one facing this.  Please advise.  EDIT : Well, I got a lot of suggestions from the answers and comments combined below and I have to say that I agree with what Cody Gray has to say and just keep on answering the questions, the returns(good or bad) may be now,later or never and just move on. However, in my own defence I would also say that I did not raised this question to pin point any user but a bad practice that I find worthy of discussing. Thanks.


Which of the following is correct?  What matters are people. What matters is people. What matter are people.  Thank you.

In my , I provided the following, problematic,  wording (especially bold italic), and I need help to better understand this issue so I can fix my answer:1          The thing is the books. (Reduced form of Sentence 2.a)         Fundamentally, Sentence 2.a (the so-called "correct" answer), is grammatically defective. Recall there is another grammatical rule: the subject and subject's complement should match in number.    A clarification is needed here. I am not suggesting here, in this EL&U question, that there is any such singular grammatical rule as indicated in the quote above.  The quote continues as follows:     The reduced sentence makes the disagreement between the subject's and complement's plurality obvious. What is one to do? Language is linear and we know "The thing is X" is better than "The thing are X", so we go with the former, which is the subject-verb agreement rule. But what is "the books" then? It must be thought of as a collective noun, even if it doesn't look or feel like one. Forcing something to be a collective noun is related to the idea of notional agreement.   Others noted that grammatically defective is too strongly worded.  There is no such "grammatical rule" for subject/complement agreement.  Please help me understand/improve upon my line of thought here.  I'm stating that Sentence 2.1 presents a fundamental "conflict" or "error" (however one might define error) at some level (morphological, syntax, grammatical, semantic):     The thing is the books.  (Or, "The thing is the objects.")   Based on the "obvious" morphosyntactic plurality conflict, the above sentence feels so wrong that I think many native speakers would think it "simply" grammatically incorrect. However, @F.E. gives counter examples:     And here are some more grammatical examples, where the number of subject and predicative complement don't agree: "They were a problem to us all", "That so-called work of art is simply four pieces of driftwood glued together" (CGEL, page 254-5). As CGEL says: "What is required is semantic compatibility, not syntactic agreement . . .". There are more examples on page 512: "The only thing we need now is some new curtains", "The major asset of the team is its world-class opening bowlers", "Our neighbors are a nuisance", "This gadget is five different tools in one".   I think all the examples given above can be explained as notional agreement.    Question 1: If we explain this phenomena in terms of notional vs syntactic agreement, where does "grammatically correct/incorrect" fit in?  Question 2: Can a simple sentence such as "The thing is the objects." be grammatically incorrect while more complex sentences such as "The thing is four pieces of driftwood glued together." be grammatically correct?  (The answer, in my mind, must be no; this is my conundrum.)  Question 3: Would it be better to say that Sentence 2.a has a low level of (linguistic) ?   Question 4: How about a low level of  and that it's semantically difficult to be (linguistically) ?    Question 5: Do we simply draw a hard line and say "The thing is the objects." is 100% grammatically correct?  I didn't particularly like this option based on intuitive notions of "grammatically correct".    1. Please help me and be kind; I'm trying to improve my understanding. I'm looking for cool, objective advice on how to look at this.  I numbered my questions so they can be easily referenced, if desired.  My preference is the final answer would sufficiently answer all the questions, but of course that can be done explicitly or implicitly.


Given the C code below:  int nSum       = 0; // pNumber is 9109190866037 int nDigits    = strlen(pNumber); int nParity    = (nDigits-1) % 2; char cDigit[2] = "\0"; for (int i = nDigits; i > 0 ; i--) {   cDigit[0]  = pNumber[i-1];   int nDigit = atoi(cDigit);    if (nParity == i % 2) {     nDigit = nDigit * 2;   }    nSum += nDigit/10;   nSum += nDigit%10;   printf("NUMBER: %d\n", nSum); }   Outputs:  NUMBER: 13 NUMBER: 13 NUMBER: 16 NUMBER: 22 NUMBER: 29 NUMBER: 29 NUMBER: 38 NUMBER: 39 NUMBER: 48 NUMBER: 48 NUMBER: 50 NUMBER: 59 NUMBER: 59   And this JavaScript code (written in TypeScript, so there actually is typing involved here as well, but it is mostly inferred):  let nSum = 0; let nDigits = partialIdNumber.length; let nParity = (nDigits - 1) % 2; let cDigit = "\0"; for (let i = nDigits; i > 0; i--) {    cDigit = partialIdNumber[i - 1];   let nDigit = parseInt(cDigit);    if (nParity == i % 2) {     nDigit  = nDigit * 2;   }   nSum += nDigit / 10;   nSum += nDigit % 10;   console.log("NUMBER: %d", nSum); }   Outputs:  NUMBER: 14.3 NUMBER: 14.3 NUMBER: 17.5 NUMBER: 24.1 NUMBER: 31.700000000000003 NUMBER: 31.700000000000003 NUMBER: 41.5 NUMBER: 42.6 NUMBER: 52.4 NUMBER: 52.4 NUMBER: 54.6 NUMBER: 64.5   NOTE: Both these implementations are the same, just different languages.  The C code produces the expected results and JavaScript doesn't.  Questions   What assumptions does JavaScript make in order to produce that output? What part of my JavaScript code would I have to change to produce the desired output?

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


The translate: tool available to mods in chat seems to be broken. It refuses to translate things for me:  (this was in the ) This has been confirmed to not work very often for other mods in the TL as well. Can we please fix this, if it's not a problem on the Bing side?

Up till a few days ago, moderators in a chatroom were able to get the Feeds chatbot to translate things for us using the translate: blah or translate xx: unblah commands. This was disabled for regular users  but it’s always still worked for moderators.   Sometimes we can still get it do something or other, but not often, not consistently, and not well: for the most part it just sits there like a dead parrot.  This is a useful and convenient tool. Could we please get it fixed?


I was customizing my ubuntu 20.04 to look like mac os catalina. I have followed normal protocols for customization including gnome-tweaks, dash to dock and blyr installation. So after the full customization, I had changed my dock to "bottom" position. However, now I am stuck with two docks. One is the original ubuntu dock, another is mac os dock (where the icons enlarge on hovering). Moreover, in the mac os dock, the icons are pixelated. Please let me know how to fix this issue.     Already tried "Show all monitors" and "switch off ubuntu dock" processes.  Actually, initially I had installed latte-dock for this mac os themed dock, after which I uninstalled latte dock but this os themed dock refuses to disappear.

What's going on here? I've installed the  on Ubuntu 17.10. Everything was cool, and as I was trying to hone and tweak the look of my desktop, at some point the shortcuts bar (dock?) on the left is duplicated.  (Click image to enlarge) The default, which normally disappears with Dash to Dock, is there underneath the one that usually shows up when I install Dash to Dock. Why? I've tried to go through the options for Dash to Dock, the GNOME Tweak Tool, and the regular Ubuntu settings, but I can't figure it out.


Recently, Pokemon Go released an update featuring a reworked Pokemon detection system -- changing "Nearby" to "Sightings".  Is there any difference between the two?

With the new update, we now have "Sightings." However, there is no indication of how this differs from "nearby Pokémon", though in the patch notes, it states they are testing a variation of "Nearby Pokémon" which appears to be the "Sightings." How do "Sightings" differ from "Nearby Pokémon"?


One of my Pi's is reporting the below errors when performing apt update/apt-get update:  E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/bionic/multiverse/source/Sources.xz  File has unexpected size (181064 != 2744). Mirror sync in progress? [IP: 91.189.88.150 80]    Hashes of expected file:     - Filesize:2744 [weak]     - SHA256:20434afedac422302fd0fcd17ed5aa35cc9cd66bba2d75daba96a2b788542036     - SHA1:4f85e4357cb0dd6a7b378368419ca53f96dbe971 [weak]     - MD5Sum:d010ff44056900efeec87e97ccdd9982 [weak]    Release file created at: Sun, 04 Aug 2019 04:39:28 +0000 E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/bionic/restricted/source/Sources.xz E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/bionic/restricted/binary-arm64/Packages.xz E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/bionic/restricted/i18n/Translation-en.xz E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/bionic/multiverse/binary-arm64/Packages.xz E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/bionic/multiverse/i18n/Translation-en.xz E: Some index files failed to download. They have been ignored, or old ones used instead.   I've read plenty of times that people say to "remove" the repository, or "wait", however, I have 2 identical RPis, and one doesn't have a problem connecting to the repositories. I've also seen people say to "wait" a few hours, but this has been going on for a week now, and it's an official Ubuntu repository (multiverse) that appears to be erroring.  Both have the same repositories, no additional ones in /etc/apt/sources.list.d/. Both are running Ubuntu 18.04 Server. The 2 Pis are built to be the same, they even replicate things to each other (such as OpenLDAP), and were working fine for months.  Any ideas why one Pi is having trouble?

When I check for updates, I get a "Failed To Download Repository Information" error.   This is what comes up under details:   W: Failed to fetch gzip:/var/lib/apt/lists/partial/us.archive.ubuntu.com_ubuntu_dists_natty_main_source_Sources  Hash Sum mismatch,  E: Some index files failed to download. They have been ignored, or old ones used instead.


I have installed Ubuntu 19.04 Disco Dingo a week ago in my computer. When I try to add a new repository with this command (sudo add-apt-repository ppa:gezakovacs/ppa this is only an example) the terminal shows this text when I do a update with sudo apt-get update.   E: El repositorio «ppa.launchpad.net/gezakovacs/ppa/ubuntu disco Release» no tiene un fichero de Publicación. N: No se puede actualizar de un repositorio como este de forma segura y por tanto está deshabilitado por omisión. N: Vea la página de manual apt-secure(8) para los detalles sobre la creación de repositorios y la configuración de usuarios.     Can you help me? Thank you.

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


My profile in Stack Overflow Careers shows the following:        I want to know what is the meaning of this?

Is there a meta for careers? If so, sorry this question should be migrated.  I'd love to know what this truly means. top 10% out of... 4 million users? top 10% out of the 100 that have asked or answered a question with this tag?


I came across the formula (24) in the WolframMathWorld article on Web page  where no source of the proof could be identified by me.   The formula is $$\prod_{k=1}^{\lfloor \frac n2\rfloor}\sin(\frac{k\pi}{n})=\sqrt{\frac{n}{2^{n-1}}}$$  I am near a proof but it is rather intricate and maybe awkward and much to complicated.  Does anybody know the source of the original proof or is there an elementary homework-style one without deeper necessary experience ?

How to prove $$ \prod_{k=1}^{n-1} \sin\left(\frac{k\pi}{n}\right) = \frac{n}{2^{n-1}}$$ and $$ \prod_{k=1}^{n-1} \cos\left(\frac{k\pi}{n}\right) = \frac{\sin(\pi n/2)}{2^{n-1}}$$


We have a square. The length of a side is 1. We pick a random dot on it. Should find the probability that of the distance between that dotes and the side lines of a square is smaller than the distance between the dot and the diameters of that square.  I tried to view it geometrically and found no matching case. Is the probability 0? Or is this a NULL event?

If a point is randomly chosen from a square, whose sides are equal to 1, find the probability that the point's distance from a side of the square is less than the distance of that point from the closest square diagonal.   I am not sure how to picture this at all, really confusing. Any help is appreciated.


I am still getting used to dual running Ubuntu on my Windows 7 machine using Wubi. I currently have Ubuntu 12.01 and want to upgrade to 13.04. According to the instructions here :  I first need to launch the dash and search for an "Upgrade Manager". I do that but the only option I get is a software updater.   Any help?  PS, I am still getting used to using a terminal so I would really appreciate not using the terminal quite yet till I am more familiar with it (if at all possible).

Ubuntu has discontinued wubi.exe and i know that when you install the ubuntu 13.04 developer version with wubi you can only login as a guest. I have previously installed ubuntu 12.10 with wubi.exe if i upgrade to 13.04 will everything work normally?


I am not sure if the title is correct, my problem is that I have a class and functions inside it, I would like to check if the value for the function is set and if not set other value  class some_class {     private $width;      function width( $value )     {         // Set another default value if this is not set         $this->width = $value;     } }  $v = new some_class();   // Set the value here but if I choose to leave this out I want a default value $v->width( 150 );

In the PHP manual, to show the syntax for functions with optional parameters, they use brackets around each set of dependent optional parameter. For example, for the  function, the manual reads:  string date ( string $format [, int $timestamp = time() ] )   Where $timestamp is an optional parameter, and when left blank it defaults to the  function's return value.  How do you go about creating optional parameters like this when defining a custom function in PHP?


Can someone tell me in laymens terms what this is?  $$K_i = \mathrm{Hash}(Z \| \mathit{Counter} \| [\mathit{SharedInfo}])$$  What do the double pipes represent?

I am studying elliptic curves problems, which also includes study of related protocols such as ECIES. The problem is that I don't understand the notation $\|$. What does this operation mean?   Some stuff is mentioned on , but this algorithm is better explained in the book Guide to Elliptic Curves. This operation is mentioned in Alice's 3rd step:  $$ k_E \| k_M = \operatorname{KDF}(S \| S_1) $$


Prove if true or find a counterexample....  The product of $x y $ of two real numbers $x$ and $y$ is irrational then at least one of the $x$ or $y$ must be irrational.

Can anyone confirm if my proof is correct, please?  Claim:- “If $x$ and $y$ are real numbers and their product is irrational, then either $x$ or $y$ must be irrational.”  Proof:-   Assume that both $x$ and $y$ are rational. Now, let $x = \dfrac pq$ and $y = \dfrac mn$ since both of them are rational. $xy =\dfrac pq * \dfrac mn = \dfrac{pm}{qn}$ Thus, if the product $xy$ can be written as a fraction, it's not a irrational number. Therefore if one of $x$ and $y$ is not irrational, then the product is not irrational.  By the principle of proof by contraposition, If $x$ and $y$ are real numbers and their product is irrational, then either $x$ or $y$ must be irrational.


I read everywhere the famous, but offhand statement that "the universe began from a single point" and this bugs me because that surely isn't true.  My understanding has always been that this was an oversimplification for the sake of explaining it to children when it fact the universe is - and always has been - infinite. The observable universe has a size, but surely no one is seriously suggesting that the observable universe is all there is? That's just the farthest we can see, what with space expanding faster than light and what not. But surely the truth of it is that the universe goes on forever in every direction and has no "centre".  Then it seems to me that the concept of everything start from a "point" is just silly. Infinite density, yes. But surely it still had infinite size? I had always thought it quite obvious that the universe "started" as an infinitely dense, infinitely sized, "clump" of energy which gradually expanded and cooled as the energy was distributed over a larger space (because space itself is expanding, not because the "point" expands).  Am I at odds with the scientific community on this? Do people honestly believe everything start from a literal singularity? A single point? Or is that just the result of only talking about the observable universe which has a definite size? But the universe as a whole is infinite, surely, so how it possibly have come from a single point? I understand that if you assume the observable universe is all there is then when you extrapolate backwards in time you end up with a singularity, but the observable universe is just a bubble in an infinite universe.

TV documentaries invariably show the Big Bang as an exploding ball of fire expanding outwards. Did the Big Bang really explode outwards from a point like this? If not, what did happen?


Let $F$ be a field, $a$ an element of $F$ and $p$ prime. How do I prove that     $f=X^p-a\in F[X]$ is irreducible iff $f$ has no root in $F$?   Honestly, I have no idea how to approach this. Maybe somebody can give me a push in the right direction?

Hungerford's book of algebra has exercise $6$ chapter $3$ section $6$ [Probably impossible with the tools at hand.]:     Let $p \in \mathbb{Z}$ be a prime; let $F$ be a field  and let $c \in  F$. Then $x^p - c$ is irreducible in $F[x]$ if and only if $x^p - c$   has no root  in $F$. [Hint: consider two cases: char$(F) = p$ and   char$(F)$ different of $p$.]   I have attempted this a lot. Anyone has an answer?


The origin of logistic regression is actually logistic curve which varies from the value 0 to the value 1. It looks like the letter S, and it specifies the growth of species.  If our data distribution is in the form S, we can use this logistic curve to represent our data (regression).  However, logistic curve can also be used in classification. Since it takes the values between zero and one, it is usable in also classification.  My confusion starts in this point. Why do we use different loss(cost) functions in logistic regression and logistic regression classification ?  $Loss = L(w) = \sum_{n=1}^N (\sigma(x_n^\top w + b) - y_n)^2$  $Loss = L(w) = \sum_{n=1}^N -y_n\log(\sigma(x_n^\top w + b))- (1-y_n)\log(1 - \sigma(x_n^\top w + b))$  The first loss function specified above is used for logistic regression. The second one is for logistic regression classification.   Actually, In both problems, we tune logistic curve perfectly to minimize loss function. Hence, we can use first loss function, in which least square is used, for also classification problem.  I tried to justify this idea, and I took a reply from someone. In the reply, the following explanation is written:  First loss function is not used for classification, since first loss function depends on least square technique. Least square technique is used to minimize distance between ground truth and predicted labels. Minimizing this distance enables us to represent our data perfectly, which refers to regression. However, we do not want to perform regression. We want to perform classification. For classification, loss function must be more sharp, which means that it must make the mistake more noticeable. Hence, logarithm is used in loss function of logistic regression classification.   What do you think about this explanation. Is it true ? Is there any other perspective which explains why we do not use first loss function in logistic regression classification ?

I am trying to use squared loss to do binary classification on a toy data set. I am using mtcars data set, use mile per gallon and weight to predict transmission type. The plot below shows the two types of transmission type data in different colors, and decision boundary generated by different loss function. The squared loss is $\sum_i (y_i-p_i)^2$ where $y_i$ is the ground truth label (0 or 1) and $p_i$ is the predicted probability $p_i=\text{Logit}^{-1}(\beta^Tx_i)$. In other words, I am replace logistic loss with squared loss in classification setting, other parts are the same. For a toy example with mtcars data, in many cases, I got a model "similar" to logistic regression (see following figure, with random seed 0).  But in somethings (if we do set.seed(1)), squared loss seems not working well.  What is happening here? The optimization does not converge? Logistic loss is easier to optimize comparing to squared loss? Any help would be appreciated.  Code d=mtcars[,c("am","mpg","wt")] plot(d$mpg,d$wt,col=factor(d$am)) lg_fit=glm(am~.,d, family = binomial()) abline(-lg_fit$coefficients[1]/lg_fit$coefficients[3],        -lg_fit$coefficients[2]/lg_fit$coefficients[3]) grid()  # sq loss lossSqOnBinary<-function(x,y,w){   p=plogis(x %*% w)   return(sum((y-p)^2)) }  # this random seed is important for reproducing the problem set.seed(0)  x0=runif(3) x=as.matrix(cbind(1,d[,2:3])) y=d$am opt=optim(x0, lossSqOnBinary, method="BFGS", x=x,y=y)  abline(-opt$par[1]/opt$par[3],        -opt$par[2]/opt$par[3], lty=2) legend(25,5,c("logisitc loss","squared loss"), lty=c(1,2))


i have forgotten the screen lock on my galaxy pocket. Right now my phone its unlock, but i want to disable or change screen lock pin and i cant remember the pin a.set before. Please help how to remove it complete it, I have setted up the screen display up to 30 minutes so the screen doesnt lock.

My son has an impression tablet 10 and has forgot the lock pattern. How can we reset it without knowing the code?


I am using mac, and /etc is just a symlink to /private/etc, which contains hundreds of (important) configuration files, and the total size of /private/etc directory is smaller than 1 MB.  Is it a good way to backup these files using git? If not, why?  What might be some side effects?  Edit: as user ivanivan pointed out, there might be security concerns for some file containing passwords or keys. Can you give me some example of these files? (e.g. ssh keys and /etc/shadow)  Edit: maybe I can encrypt the .git dir before pushing it to a private remote repo?  Edit: git doesn't track file permission and files in /etc have all kinds of permissions. using git may cause some serious problems. On the other hand, etckeeper handles file permissions properly.

I would like to keep track of changes in /etc/  Basically I'd like to know if a file was changed, by yum update or by a user and roll it back if I don't like the chage. I thought of using a VCS like git, LVM or btrfs snapshots or a backup program for this.   What would you recommend?


Is the sentence "This is the first time I'll be taking the exam." grammarly correct? If so, why using the present continuous tense, and what about "This is the first time I take the exam."

I have been there first time.   The reason why I think this might not be natural is that the expression "first time" seems to describe "past". You do not use the present perfect with an adverb indicating "past", in my understanding.  However, I feel the phrase below is not that funny.     This is the first time that I have been there.   I am wondering about the relationship between "the first time" and "I have been there". "That" could behave like a relative adverb. If that is the case, the antecedent of "that"—"the first time"—is shared with the following clause: "I have been there". Then, is it OK to say "I have been there first time"?  By the way, Google searches for "" and " in the UK domain show just 33 hits for the first phrase and 10 hits for the second.


The Google page says     Important notice: OpenID2 for Google accounts is going away on April 20, 2015. .   Looks like Google is giving a decent warning. This warning is NOT shown when logging into MSE, SO, etc. (Presumably because they use oauth2 instead)

Apparently, for some reason, . I got this notice while logging in with Disqus, but not with Stack Exchange.  So... is Stack Exchange going to be affected by this? Do I need, or want, to add extra login methods to my Stack Exchange account to ensure I can still log in come April?


Which is a good book on math History?  I want to give it as a gift to a mathematician.

I'm trying to find good books on the history of mathematics, dating as far back as possible.  There was a similar question here , but mostly pertaining to Philosophy, and there were no good recommendations on books relating specifically to Math History.


Is there a way to get a windows always on focus?   I mean not just on top, but with the focus on it if another window pops up on the screen.

I'm using Maverick with Compiz enabled.  I've searched AskUbuntu and Google. AskUbuntu doesn't have anything on this topic and everything Google turns up is a couple years old.  I'm doing browser tests and my tests are constantly spawning new Firefox windows. The problem is, when the window is spawned it takes focus. This is incredibly annoying as I'm usually in the middle of typing somewhere else. This doesn't only happen with my tests, but is the most common example I run into. Sometimes my IDE decides it wants focus when something special happens (like when something is done compiling) and then later I'll find fragments of IM messages I've typed in my code. This is driving me crazy. I've looked in both Gnome settings and Compiz settings and can't find a way to prevent that from happening.  Does anyone know of a way to prevent an app from stealing focus when it is opened? I'd rather have the taskbar flash at me or something to get my attention.


So I went through coding a python application, which I will put on a flash drive (maybe a few of them) and give it to a person, I'll probably use py2exe to convert it to an executable file as a way to hide the code up a bit (.exe), but here's the problem: I don't really trust these people and I'm not so sure they may use it elsewhere which I don't want so I thought I'd put it on a USB drive and try to get it to be protected somehow so they can use it but not copy, cut or delete it. Is there a way around this?

I am trying to make folder that everyone can view and can't copy,modify.    For all answers.I thinking about specially ms office files. I tried following methods  Software  - copy protect    - anti copy    This method can't protect save as and upload  MS office macro    Users can enable,disable macros.  MS office restriction    This is best choice but can't protect from file uploading.   Almost I found the solution. Way is combination of MS office restriction and restrict access from browsers using firewall or antivirus. But I don't exact how to do this.


I'm just learning JavaScript, so I really apologize if this question is a little basic, but I just can't find any resources that explain it, or I'm just too inexperienced to understand them. As part of learning the language I'm making a simple text rpg as practice, and that's where the issue came up.  I'd like to be able to dynamically add dialogue choices using a function, that will result in some action happening when you click on them.  This works perfectly for the final time I call this function, but for for all the preceding times I call it, the event listeners aren't properly being attached, and I don't understand why. Here's the HTML doc: <!DOCTYPE html>               <title>JavaScript RPG</title>

        Here is the code for the function to add dialogue: function addDialogueOption(dialogueOption, optionNumber) {     //Set dialogue text     document.querySelector("#dialogueBox").innerHTML +=          "
" +          dialogueOption + "
";      //Link option to result     document.querySelector("#dialogueOption" + optionNumber).addEventListener("click",      function() {window.alert("Not enabled");}, false); }  And here is how I call the function later on: addDialogueOption("Investigate rustling.", 1); addDialogueOption("Take a nap.", 2); addDialogueOption("Take a nap.", 3); addDialogueOption("Take a nap.", 4); addDialogueOption("Take a nap.", 5);  Any help and explanation you could provide on why this is happening would be really helpful! Thanks!

In the following example code, I attach an onclick event handler to the span containing the text "foo". The handler is an anonymous function that pops up an alert().  However, if I assign to the parent node's innerHTML, this onclick event handler gets destroyed - clicking "foo" fails to pop up the alert box.  Is this fixable?
      foo


A number when divided by $902$, $802$ and $702$ leaves remainder of $602$, $502$ and $402$ respectively. What would be the minimum remainder of when the number is divided by $2005$?  My attempt: For the given number $n$, $n + 300$ is divisible by $902$, $802$ and $702$. Hence $n + 300$ can be written as $\mathrm{lcm}(902,802,702)\cdot K$ where $K$ is the integer and we can keep varying $K$ from $1$ onwards to manually check the minimum remainder. However this is not a great approach. Any simplistic approach to this problem would be appreciated.

I am trying to find all integers that give remainders 1,2,3 when divided by 3,4,5 respectively.  So I start defining  $$a_1=1, a_2=2, a_3=3,$$$$ m_1=3, m_2=4, m_3=5,$$$$ m_1m_2=12, m_1m_3=15, m_2m_3=20,$$$$ m=60$$ All the moduli are pairwise coprime, so by the Euclidean Algorithm $$12x+5y=1\Rightarrow x=-2, y=5.$$ $$15x+4y=1\Rightarrow x=-1, y=4.$$ $$20x+3y=1\Rightarrow x=-1, y=7.$$ Therefor a solution should be  $$20\cdot(-2)\cdot1 +15\cdot (-1)\cdot 2+12\cdot (-1)\cdot 3=-40-30-36=-106$$ But under mod 60, this implies a solutions should be of the form, $60t+14$.  But it is not.  THis is not right.  Why did this technique not work?


my task is to find, and mark, all the points from a point cloud that are inside a 3D rectangle. I have the coordinates of all the 8 vertices. Is there a mathematical formula which I can use? To be precise, I'm working with python and all the points are inside a np array, so if someone knows a library that can do that, I'm open to suggestions. Thanks a lot.

I have a cuboid in 3D space, it is not regular at all.  I do have the coordinates of its 8 vertices and my problem is how to determine a given point coordinate is inside or outside this cuboid.  I have so far though that if I can calculate the distance of the point to each of the 6 side planes then I can find out the answer. Assume I can calculate for each side the plane formula with the normal pointing out of the cuboid, then for the point to be inside all distances must be negative, right? If one of the 6 distances is positive then the point is on the outside.  Is this the shortest and simplest approach?


Do the following sentences have the same meaning?        She put on  makeup.   She wore  makeup.

Is there a difference between "wear make-up" and "put on make-up"? If yes please give some examples.


I'd like to put a caption on the left of the table (not meaning text is left-aligned) like this:  \begin{table}[t] \caption{caption left} \label{tab:1} \centering     \begin{tabu} to 1 \linewidth{|X[2.2,l] |X[3.0,l] |X[0.65,c] |X[0.65,c]| X[0.65,c]|} \hline     A & B & C & D & E\\\hline\hline     A & B & C & D & E\\ \hline     \end{tabu} \end{table}

How can I display the table caption at the left side?  Thank you,


I am a linux newbie, tech oldie.  I am setting up a system with Lubuntu 14.04. Although, when I ran the installation I created two partitions -- 1/2 for quickie backups and 1/2 for the installed system -- lubuntu ignored that and took my entire disk.  Yesterday, I spent a lot of time with the Redo Rescue disk manually recreating what I wanted.  Now, I have the following paritions:  /dev/sda1 ext2 /boot +- 200MB /dev/sda2 extended +- 244GB /dev/sda3 ext2 +- 220GB   sda1 and sda2 were created by the installer. I manually created sda3 after resizing those.  within sda2 is a logical volume  sda5 lvm2 pv lubuntu-vg   within sda 5 there are a swap partion and the root partition and nothing else. these were also created by the installer, but I resized them yesterday.  I want to backup sda1 and sda2 to sda3. I have been at this long enough to know that gives me zero protection from a disk failure. I just want to quickly be able to restore my work up to a certain point if I screw something up as I am tweaking the new system.  I have the qt4-fsarchiver LiveCD, the SystemRescueCD LiveCD and the Redo Rescue LiveCD.  As a linux newbie, I have been unable to figure out how to do this on any of these.

I like 'Disks' (gnome-disk-utility) and its ability to create backups of system partitions.    But at some point I read on the internet about a program that would create such images that are not as large as the whole partition, but only as large as the files on it. Now I cannot find it again.  Is there such an utility?


SQL> insert into DEPT values(101, 'RAMESH'); insert into DEPT values(101, 'RAMESH')         *      ERROR at line 1:       ORA-01950: no privileges on tablespace 'USERS'   I cant sort the above problem?

Earlier I created a user :  SQL>create user suhail identified by password SQL>User created. SQL>Grant create session,create table to suhail; SQL>Grant Succeeded.   but when I login as suhail and try to create a table I get an error saying ORA-01950: no privileges on tablespace 'SYSTEM' .  What error is it ? Why does it occur ?    SQL> connect suhail Enter password: Connected. SQL> create table suhail_table(name char(10)); create table suhail_table(name char(10)) * ERROR at line 1: ORA-01950: no privileges on tablespace 'SYSTEM'   I am using Oracle Database 11g Express Edition Release 11.2.0.2.0


Is it possible to address a comment to more than one person ?

Now this is probably a surprise to many since I always see thousands of comments like :  @Sarfraz, @balpha just told you they did in the first comment he wrote. Also, allowing only one Stack Overflow user to be logged in per IP address would be problematic for networks with shared IPs.  What's surprising is that apparently the notification will trigger only for Sarfraz and not for balpha. As you can see from the :  Only one person can be replied to at a time in a comment. The first one in the string wins.  I propose to increase the limit to let's say 3 or 5 people; it won't hurt (never seen that feature being abused) and especially many people believe it already works that way.


I would like to be able to take a list of unknown length in for function parameters like this: With a list lis = [1, 2, 3, ...] and a function def func(a, b, c, ...): ... the elements of the list go into the function as individual parameters, func(1, 2, 3, ...) *not func([1, 2, 3, ...]) Is this possible?

In the following method definitions, what does the * and ** do for param2?  def foo(param1, *param2): def bar(param1, **param2):


We know that there is a fundamental theorem that is: $$a^2+b^2=c^2$$  Then it is given that the product of a,b and c are divisible by 5 where $a,b,c\in \mathbb{Z}$. Using numbers, I know for certain that this is in fact true. But by using $\mod{5}$, I am not certain how I can approach this question.   Help is greatly appreciated.

My question is about proving that if $$a^2 + b^2 = c^2,$$ then 5 divides abc. a,b,c are positive integers.


TL;DR : default shell man page says there's vi editing mode, but set -o vi doesn't actually enable it  In many shells, including dash the POSIX standard dictates that set -o vi will enable vi editing mode, in which user of interactive shell can navigate line using vi-style of shortcuts. In dash ( Ubuntu's default shell symlinked to /bin/sh ) this doesn't work, even though man page specifies that this feature is available.  Example :  $ dash $ set -o vi $ hello wolrd^[I   What was supposed to happen there is that with Esc , Shift + i shortcut the cursor should have jumped to the beginning of the line. As you can see, I get a control character as output instead. I've asked a few users to test this in AskUbuntu Chat, and they confirmed the same behavior.   Note, that this is not related to terminal emulator - I tested it in 3 different ones: xterm, gnome-terminal, and terminator. I've tested this with other shells, bash, mksh and ksh93 - all work properly as expected, so this is dash-only issue.

In  or  it is possible to move around the typed line word by word, using  such as ESCB.   That doesn't work in  or . As far as I understand from googling, this has something to do with readline support, however nowhere I've seen it mention how to enable support for dash.   That's the core of my question: How to enable line navigation for dash


I didn't find this question or a related answer to my question.  Some spells like "Avada Kedavra" are spells that are intended to do one thing, the conjurer focuses on that spell and when they stop focusing, or the blast doesn't hit it's target, or the wizard dies, the spell ends.  A spell that opens a locked door for is another example, it either fails immediately or the door unlocks, either way the spell is over.  However, what about spells like the charming spells Harry, Hermione, and Ron used to conceal themselves?   They would get to a camp site, one of them would walk around the perimeter of the camp site and cast spells to conceal their location. Does the spell last in perpetuity? Does it only last while the conjurer is focusing on it? Does it last until it is dispelled by a counter spell? Does it just run out eventually?   I don'think the conjurer has to focus on it. It always appeared in the books and the movie that once these spells are cast the conjurer doesn't think about it again.  The charm spells are just an example. A love spell would fall into the same category as well. I believe the love spell Voldemorts mom put on his dad lasted until her mom released it and she didn't have to focus on it. There are many other examples of these types of spells as well.  You might want to consider Lily Potter's spell on the fish she gave to the professor as a gift in your answer. I believe it lasted until she died.  I don't know if each spell has a distinct amount of time that it lasts or if spells of this category follow a general rule.  Author's notes, interviews, etc. are welcome.

Looking at the questions and answer to these two questions.  &  and neither mentions the longevity of magic. I recall several instances of magic failing to last; the money that was spread at the  and the broken  on.  If I recall correctly when Voldemort died, the curses on several people were lifted.  I don't recall if any other spells fell apart with his death.  Is there any canon evidence on the the length of time a spell will live?


It's been like 8-10 hours since I encounter that problem and it really bugs me. So hopefully someone would give me a hint what I'm doing wrong.  Issue I'm using maven shaded plugin to pack my maven app to jar file, the problem which I encounter is that in Eclipse when I'm running my app all is sound, but when I try to run my app as jar file:  java -jar <my-file>   I get:   Exception in thread 'main' java.lang.NullPointerException at start.my.App.main<App.java:60>   My application works as filter and processor for files within directory from which my app is started. Traverse method simply returns list of files within directory in which my jar file is located:   @Override public List<File> traverse(String directory) {   File directory = new File(directory);   List<File> resultList = new ArrayList<File>();   File[] fList = directory.listFiles();   resultList.addAll(Arrays.asList(fList));   for (File file : fList) {     if (file.isDirectory()) {        resultList.addAll(traverse(file.getAbsolutePath()));     }   }    return resultList;  }   The line in which this problem occurs:  WalkerResult walkerResult =     walker.traverse(ClassLoader.getSystemClassLoader()                            .getResource(".")                            .getPath());   What's inside traverse method should return path to my jar file which I'm running, I think I'm doing something wrong as when I pass as path to traverse method which looks like:  WalkerResult walkerResult =     walker.traverse("C:\\Users\\Downloads");   all is fine in IDE and as in jar application.  Thanks for any hints in advance.

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 a question of multivariable analysis and I don't know how to resolve this.     The $n \times n$ orthogonal matrices form a compact subset of $\mathbb{R^{n^2}}$?   I will be very grateful for the help.

Show that the set of all orthogonal matrices in the set of all $n \times n$ matrices  endowed with any norm topology is compact.


Prove that the set of rational numbers $\mathbb{Q}$ belongs to the Borel σ-algebra of $\mathbb{R}$  I was just thinking about the method I would go about proving this I was thinking if we can write $$\mathbb{Q} = \bigcup_{x \in \mathbb{Q}} \left \{ x \right \}$$ And then if we prove the {x} is in the Borel σ-algebra then the union is too? If there's a method to prove this, It would really help thank you

Prove that the set of rational numbers $\mathbb{Q}$ belongs to the Borel $\sigma$-algebra of $\mathbb{R}$. I'm unsure about how to prove this. I'm also unsure about the difference between a σ-algebra and a Borel σ-algebra.


What is the best way and best practice to achieve this layout? Meaning it will stay consistent on iPad, Android or desktop. CSS Grids? Flexbox? Logo div should be centered on the page vertically and horizontally. Text divs should be centered in the middle of the logo div.

How can I horizontally center a
 within another
 using CSS?

Foo foo


Before interview read through your CV first. Doing this will help you answer personal questions.   What is the grammatical name and function for doing this in the sentence above?

My question is a follow-up to one in which I identified stealing and killing in a particular sentence as gerunds. Bill J commented to the effect that if objects followed these gerunds, the latter became verbs.   My questions are why and what form of the verb? For me the grammatical distinction between “I dislike killing” and “I dislike killing sheep” is simply that the gerund complement in the first becomes a gerund phrase complement in the second.


can we add a pick-list field to the Approval pagelayout ??  My requirement is i want Approvers to enter Reason for rejecting a record.  I have a picklist field on my object with the rejection reasons , i want this field to be placed on the approval page layout so that Approvers select reason from this pick-list.  Thanks in Advance.

I'm trying to get through my first SalesForce mod and it's definitely been a rocky path. I have one task I'm trying to do, but this section is holding me back.  I have two custom fields.  One a pick list and the other a text box. I have added them to the Approve/Reject Approval Request section in the Opportunity page. I added the fields through the Select Fields to Display on Approval Page Layout and they DO show up on the Approve/Reject Approval Request section. I added them in like ().  However, just the label for the fields show, the field itself is nowhere to be found and can't be used.    You can see and even use the fields when you open the Opportunity page itself, but when you go to use the Approve/Reject, you can't do anything with them or see any values.  I was never a SalesForce user and got this tossed in my lap and really don't know my way around yet. I appreciate any help on this!!  Thanks!!  Kurt


In theory, should it be possible to root your device with an APK file? Or possibly create a potential harmful application?  I know that APKs can be used as apps you can install offline, but I'm assuming it could be used to be malicious. But what all could it do? How destructive could it be? And is there even a limit; a system to protect you from stuff like this?

There are quite a few app based rooting methods. A recent review , points to some of them and there may be more apps, paid or otherwise.  From what I understand,   Plus Points   Ease of rooting Don't need a laptop or computer   Minuses   Based on exploits, so may not work if exploits are denied by OS updates Difficulty in unrooting (as I see on some forums for my device Huawei Honor 6)   Questions:    What are the pros and cons apart from above?  If a device has both options - app based rooting and rooting by methods by developers, which one should I opt for?   Note: I am not seeking app suggestion or recommendation.


I have to prove the next 3 numbers are composite numbers  $500^{27}-123^{12}$ $12^{75}+21^{75}$ $58^{32}-49^{32}$   I have no idea where to begin, if anyone can give me a hint I will be grateful. Thank You Very Much!

In respect to a larger proof I need to prove that $(n-m) \mid (n^r - m^r) $ (where $\mid$ means divides, i.e., $a \mid b$ means that $b$ modulus $a$ = $0$). I have played around with this for a while now but to no avail and would be grateful if you could help me.


Must I buy an  to get security fixes for 5 years (LTS)?   free support for nine months with security fixes, high-impact bug fixes and conservative, substantially beneficial low-risk bug fixes ... Current long-term support (LTS) releases are supported for five years, and are released every two years.

ESM is available for 12.04, which enables Advantage customers to keep receiving kernel updates and updates for many user space packages. In our case it's very important to know if we'll be able tot use Ubuntu 14.04 safely after April '19, because it is not possible to upgrade our application and migrate it to say, 16.04.


I have a String, which contains a lot of commas. I want to count all the commas in the String but I don't know how. I'm using (split(",")-1) But the problem is that if I input a String like this: One,Two,Three,Four,,, Then it returns only 3 while I want it to be 6. I think it is because split(",") returns a String[] that does not include null or empty values. Is there any way to solve this problem?

I have the string   a.b.c.d   I want to count the occurrences of '.' in an idiomatic way, preferably a one-liner.  (Previously I had expressed this constraint as "without a loop", in case you're wondering why everyone's trying to answer without using a loop).


What does it mean when we say "get set" in the phase "get ready get set go" or the phrase "on your marts get set go"?  This question focuses on the term "Get Set" not just in reference to a sport but in general.  Many times I hear people speaking about being set and ready as if they meant the same thing... however i do not believe so.. hence my question. while get ready, and go are obvious, if I were to tell someone get set.. what exactly am I saying to them?

Watching Kipper with my son tonight, I was struck by the phrase "Ready, steady, go!"  I don't often hear this sequence.  In my upbringing, it has been mostly "On your mark, get set, go!"  I had thought the difference might be between British English and North American English, but when I search for "Ready Steady Go," I get a whole lot of unrelated hits related to music.    Is there a regional preference in the usage of these phrases to start a race, or are they perhaps associated with particular sports?


Let $(F_n\mid n\in\Bbb N)$ be the Fibonacci sequence. Then $\gcd(F_m, F_n) = F_{\gcd(m, n)}$ for all $m,n\in\Bbb N$.     My attempt:  Lemma 1: $m\mid n\implies F_m\mid F_n$ (A user presented a proof )  Lemma 2: $F_{m+n}=F_{m-1}F_n+F_mF_{n+1}$ (I presented a proof )  Let $g=\gcd(m,n)$ and $d$ be any common divisor of $F_m,F_n$. From the definition of Greatest Common Divisor, it's clear that $$\gcd(F_m, F_n) = F_{\gcd(n, m)}=F_g\iff\begin{cases} F_g\mid F_m\text{ and } F_g\mid F_n\\d\space\space\mid F_g\end{cases}$$   $F_g\mid F_m\text{ and } F_g\mid F_n$   Since $g=\gcd(m,n)$, $g\mid m$ and $g\mid n$. From Lemma 1, we have $$g\mid m\Rightarrow F_g\mid F_m\quad\hbox{and}\quad   g\mid n\Rightarrow F_g\mid F_n$$.   $d\mid F_g$   From , there exists $x,y\in\mathbb Z$ such that $g=mx+ny$.  $F_m\mid F_{mx}$ [By Lemma 1] and $d\mid F_m\implies d\mid F_{mx}$. Similarly, $d\mid F_{ny}$. Thus $d\mid F_{mx-1}F_{ny}+F_{mx}F_{ny+1}$, and consequently $d\mid F_{mx+ny}$ by Lemma 2. Hence $d\mid F_g$.       Does this proof look fine or contain gaps? Do you have suggestions? Many thanks for your dedicated help!

Can any one give a generalization of the following properties in a single proof? I have checked the results, which I have given below by trial and error method. I am looking for a general proof, which will cover the all my results below:   Every third Fibonacci number is even. 3 divides every 4th Fibonacci number. 5 divides every 5th Fibonacci number. 4 divides every 6th Fibonacci number. 13 divides every 7th Fibonacci number. 7 divides every 8th Fibonacci number. 17 divides every 9th Fibonacci number. 11 divides every 10th Fibonacci number. 6, 9, 12 and 16 divides every 12th Fibonacci number. 29 divides every 14th Fibonacci number. 10 and 61 divides every 15th Fibonacci number. 15 divides every 20th Fibonacci number.


I'm trying to colourize my find command so I've added this alias function to my .bashrc.  # liberate your find function find {     command find $@ -exec ls --color=auto -d {} \; }   But there is unexpected behavior using this code. It drops my quotes.  GNU bash, version 4.4.23(1)-release (x86_64-pc-linux-gnu)  Use my function:  find ./ -name '*.pl' -or -name '*.pm'   Result:  ./lib/cover.pm ./lib/db.pm   Using the same find function but built-in:  command find ./ -name '*.pl' -or -name '*.pm'   Result:  ./auth.pl ./index.pl ./title.pl ./lib/cover.pm ./lib/db.pm ./fs2db.pl   So the second variant didn't eat my quotes and works as it should.

I'm trying to get quoted parameters of a bash script to safely be received by a nested script. Any ideas?  test.sh  #!/bin/bash echo $* bash myecho.sh $*   myecho.sh  #!/bin/bash  echo $1  echo $2  echo $3  echo $4   Sample:  bash test.sh aaa bbb '"ccc ddd"'   Result:  aaa bbb "ccc ddd" aaa bbb "ccc ddd"   Wanted result  aaa bbb "ccc ddd" aaa bbb ccc ddd


I'm trying to make it so it scans the computer for multiple files and logs it in a ListBox. That all works except when I get to the multiple types. I have tried almost everything on google.   Needed Code:  If (Directory.Attributes <> FileAttributes.System) Then                     allFiles = Directory.GetFiles("*.png;*.jpg", SearchOption.AllDirectories)                 End If   Full Code:  Dim tempDir As New DirectoryInfo("C:\")     Dim FileDetails(4) As String     Dim iTem As ListViewItem     Try         Dim allFiles As FileInfo() = Nothing         For Each Directory In tempDir.GetDirectories()             Try                 If (Directory.Attributes <> FileAttributes.System) Then                     allFiles = Directory.GetFiles("*.png;*.jpg", SearchOption.AllDirectories)                 End If                 Dim oneFIle As FileInfo                  For Each oneFIle In allFiles                     FileDetails(0) = oneFIle.Name()                     FileDetails(1) = oneFIle.FullName()                     FileDetails(2) = oneFIle.Length() / (1024 * 1024)                     FileDetails(2) = FileDetails(2).Remove(5)                     iTem = New ListViewItem(FileDetails)                     ListBox1.Items.Add(oneFIle.FullName)                 Next             Catch ex As Exception              End Try         Next     Catch ex As UnauthorizedAccessException      End Try

I am trying to use the Directory.GetFiles() method to retrieve a list of files of multiple types, such as mp3's and jpg's.  I have tried both of the following with no luck:  Directory.GetFiles("C:\\path", "*.mp3|*.jpg", SearchOption.AllDirectories); Directory.GetFiles("C:\\path", "*.mp3;*.jpg", SearchOption.AllDirectories);   Is there a way to do this in one call?


Consider the following matrix:    \begin{bmatrix} -3 & 1 & -1 &  &  &  &  & \\  -7 & 5 & -1 &  & 0 &  &  & 0\\  -6 & 6 & -2 &  &  &  &  & \\   &  &  &  4 & 0 & 1 & & \\   & 0 &  &  0 & 1 & 0 & & 0\\   &  &  &  0 & 0 & 4 & & \\   &  &  &  &  &  & -1 & -1\\   & 0 &  &  & 0 &  &  1 & -3 \end{bmatrix}  I need to find its minimal polynomial. I found that the characteristic polynomial is: $P(\lambda)=(\lambda+2)^4(\lambda-4)^3(1-\lambda)$ using the fact that for a block matrix: $$A=\begin{bmatrix} {A}_{1} & 0 & \cdots & 0 \\ 0 & {A}_{2} & \cdots &  0 \\\vdots & \vdots & \ddots & \vdots \\0 & 0 & \cdots & {A}_{n} \end{bmatrix} $$ It holds that: $\det(A)=\prod_{i=1}^{n}\det(A_i)$  Is there an easy trick to find the minimal polynomial as well?

I am currently struggling with an exercise where I have to treat a Block diagonal matrix (so it is a square matrix, where square block matrices are down the diagonal). Now I was wondering whether we can say something about the characteristic or minimal polynomial of the whole matrix, if we know the characteristic and minimal polynomial of the blocks? Anything you know could be helpful!


I need to make some sort of moving shape with chapter number inside which will be moving with scrolling pages on twosided document. Something like this:    Which package can provide me some help to implement this or it is even possible to do this?

I'm making a reference manual using scrbook. I'd like to include a "tab" that shows the current chapter number in a 1.5cm gray rectangle on the outside edge of every page. Within the rectangle would be the current chapter number. This would allow readers to quickly locate the beginning of a particular chapter by looking at the edge of the printed book.  As an added challenge, the chapter tab needs to move down the page as the chapter number increases. For example, in chapter 1, the chapter tab would be located 1cm from the top of the page; for chapter 2, it would be located 2.5cm from the top of the page (1cm white space, plus 1.5cm for the height of the previous chapter tab), and so on.  Is this possible? If so, how can do implement it?


Show that if $f: (a,\infty) \rightarrow \mathbb R$ such that $$\lim_{x\to \infty} xf(x) = L$$ where $L \in \mathbb R, $  then  $$ \lim_{x\to \infty} f(x) = 0.   $$

Let $l \in\mathbb{R} $ and $ f:(0,\infty) \to \Bbb R $ be a function such that $ \lim_{x\to \infty} xf(x)=l $ .  Prove that  $ \lim_{x\to \infty} f(x)=0 $.  Any help would be appreciated - I found this difficult to prove


Sometimes, right in the middle of a project, when I'm trying to zoom in on an object, the zoom just halts at a certain point as if I'm reached some kind of limit, even though I earlier was able to go much closer. What is the deal with this and how can I solve it?

I often find that I can zoom in to a point, but then cannot zoom any more, even when there is a lot of room to zoom to the meshes on the scene.   This is particularly annoying in the following scenario:  I often land up left clicking on the scene and the 3D cursor shifts there. I use Shift+C to shift the 3D cursor back to the origin. However, this also centers the view on the cursor and shifts the view to show all objects, and sometimes this zooms things way out – at this point, if I try to zoom in, I can zoom in to a point (using the pinch/zoom on trackpad), but then it stops zooming in.   How do I zoom in after that? Is there anything else I am doing wrong in this case?


I am using an Oracle DB with which I'm not familiar.  I would like to export something like a matrix of all tables and fields.  Is this possible?  Thanks.

How do I query an Oracle database to display the names of all tables in it?


I close-voted  and edited the auto-generated comment after that.   Now the question is closed and the comment is removed. I  on meta that such comments would stay if EditCount is not null, but that doesn't seem to be the case anymore since at least a few weeks.  Was this change intentional?   While on the subject: can the generated comment be made to look more like a proper sentence, especially with a capital P for Possible and a period on the end?

A user just posted his question a second time here on meta after the first was closed as a duplicate. I wrote a comment on the second post, explaining that the answer to his question is in the linked duplicate and that he shouldn't circumvent the closure process by asking a second identical question.  When the second post was closed as a duplicate my comment was automatically deleted. As far as I understand this is a heuristic that removes obsolete comments, which it considers every comment that contains a link to one of the duplicates.  This heuristic is too aggressive and removes comments that go beyond "Duplicate here: link". I suggest that it should be changed to only remove the default duplicate comment, and not any comment that was edited by the owner nor any free-form comment that happens to include a link to the duplicate.  This also triggers for any comment that contains the word "duplicate" and link to any question, not only the question being chosen as duplicate, which makes this much worse.


I'm making a game where things randomly generate. It used to work, but now all the sudden they keep spawning in the same area every time. does anybody know a fix?

I'm trying to make a game where the damage you deal is rolled by a dice. It all works. However, it keeps on giving the same values in a row so it isn't entirely random  ini_open("Health.ini"); attack = ini_read_real( "Attacks", "Felix", 0); ini_close(); global.damage=0 repeat(attack){ global.damage=irandom(6) }   if (global.damage ==0){instance_create_depth(300, 400, 0, obj_numbers0)} if (global.damage ==1){instance_create_depth(400, 400, 0, obj_numbers1)} if (global.damage ==2){instance_create_depth(500, 400, 0, obj_numbers2)} if (global.damage ==3){instance_create_depth(600, 400, 0, obj_numbers3)} if (global.damage ==4){instance_create_depth(700, 400, 0, obj_numbers4)} if (global.damage ==5){instance_create_depth(800, 400, 0, obj_numbers5)} if (global.damage ==6){instance_create_depth(900, 400, 0, obj_numbers6)}   The attack value is 1 because it is only one dice that is used for damage for now. The software I am using is Game Maker Studio 2


I have a question regarding canonical URLs. My problem is that I think I understand canonical URLs but I am also not entirely sure.  I have a website that is starting to score really well in Google. So that's fine. However I want to create some promo sub-pages. And using canonical URLs is good. But I am afraid that if my logic has some errors I might screw up that what I've obtained and worked very hard for to obtain.  So here is my situation.  I have a website : www.example.com  We have several pages on this website   www.example.com www.example.com/about-us.html www.example.com/how-do-we-work.html www.example.com/our-priceplan.html www.example.com/book-our-service.html www.example.com/contact-us.html   Now we would like to add some promo landingpages at promotion.example.com This page should have the following pages   promotion.example.com promotion.example.com/about-us.html (duplicate from the main domain) promotion.example.com/our-priceplan.html (* new priceplan, just for this promotion *) promotion.example.com/contact-us.html (*duplicate from the main domain *)   Since :   about-us.html contact-us.html   Are duplicates from the original ones set in the main domain example.com, I understand that I should set for the first :  <link rel="canonical" href="https://example.com/about-us.html" />   and  <link rel="canonical" href="https://example.com/contact-us.html" />   for the second.  My question is.. Did I understand this correctly to avoid any penalty. There is a lot depending on it for me. Hence my question.  Thanks in advance.

This is a general, community wiki question regarding duplicate content.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .     What does Google consider to be duplicate content? Will the way I am presenting my content result in a duplicate content penalty? How can I avoid having my site's content treated as duplicate content?


There was a request in the Workplace Chatroom from a someone on Writers Beta to see if we could share some knowledge on a . Myself not having used it before did not have an account so I created one and received the 100 rep association bonus. The question is protected so I would need to have at least 10 reputation to answer it but when I have gone to the question I am unable to answer it at all. There is no answer box...I double checked that you can use reputation gained from the  and there is nothing in there about not being able to.

Questions can be protected (i.e. marked "highly active").   What does it mean for a question to be protected? Why are some questions protected? Who can protect and unprotect questions? Who can answer a protected question? How are protected questions displayed? When should I protect or unprotect a question? When does the Community user protect a question?


My idea is that the vector space W1∩W2 is a subspace of both W1 and W2, and so it has a basis B which is a linearly independent subset of both W1 and W2.  We know that we can always take a linearly independent subset of a vector space and complete it to a basis of that space, and so do that with B for W1 to obtain B∪S1, and also do that for W2 to obtain B∪S2.   Where do I go from here, and how can I use it to get the W1+W2 side?

$\dim(U_1+U_2) = \dim U_1 +\dim U_2 - \dim(U_1\cap U_2).$  I want to make sure that my intuition is correct. Suppose we have two planes $U_1,U_2$ though the origin in $\mathbb{R^3}$. Since the planes meet at the origin, they also intersect, which in this case is a one-dimensional line in $\mathbb{R^3}$. To obtain the dimension of $U_1$ and $U_2$, we add the dimensions of the planes (4), and the subtract the dimensions of the line (1), which results in (3).   *additional question(s):   Can we generalize this notion to $\mathbb{F^{n}}$?  Suppose we have an additional case where $U_1$ and $U_2$ are planes in $\mathbb{R^3}$, but $U_1 \subseteq U_2$. In this instance, $dim(U_1 + U_2) < 3$, because the first two-dimensional plane is contained in the second and as a result, the dimensions of the subspaces when summed cannot exceed two. Since both subspaces $U_1,U_2$ are two dimensional and $U_1 \subseteq U_2$, then their intersection is also two-dimensional, concluding $dim(U_1+U_2)=2+2-2 = 2$.  Is this proper intuition?


I have a problem with the Apple URL.  @online Google works fine, but when I add the @online of Apple, it generates the error: \verb doesn't match its definition!!!  \documentclass[12pt]{report}  \usepackage{hyperref} \usepackage[backend=bibtex,style=numeric,natbib=true,sorting=none ,maxbibnames=99]{biblatex}  \addbibresource{library.bib}  \begin{document}  User Interface \cite{Google}. User Interface \cite{Apple}  \end{document}   Bib file:  @online{Google, author = {Google}, title = {User Interface Guidelines from Google}, url = {https://developer.android.com/guide/topics/ui/overview.html}, year = {}, note={Accessed December 30, 2017}}  @online{Apple, author = {Apple Inc}, title = {Apple iOS Human Interface Guidelines}, url = {https://developer.apple.com/ios/human-interface-guidelines/overview/design-principles/}, year = {}, note={Accessed December 30, 2017}}

Currently having problems with compiling my Master's thesis after downloading the newest version of TeXStudio and MiKTeX. The error message is as follows:  Use of \blx@bbl@verbadd@i doesn't match its definition. \verb   The only other place I found a similar question regarding this error message was found here:   I am not sure how this applies to my problem, but from what I understand this is due to some problem in an external file. If you need the bibliography-entry, I can provide you with that on short notice, though it is rather long (which is why I didn't include it here in the first place).  I am using Mendeley Desktop v1.16.1 to automatically generate my BibTeX database.   I am using biblatex as follows:  \usepackage[backend = bibtex,         style = numeric-comp,         sorting = none,         natbib = true,         doi = false,         isbn = true,         hyperref = true]{biblatex}   I also have some code to change how the bibliography output, but I doubt it is causing the problem, as commenting it out did not help.  Hope anyone knows what causes my problem and how to fix it.  Thanks.


Was messing around with an external drive and wanted to change the permissions of a folder. However, I accidentally ran sudo chown myuser -r /. I have never felt so dumb in my life. I immediately realised what I had done and canceled it, but it was too late.  I'm on Arch. How screwed am I. Is this fixable or is it a lesson to be remembered?  Kids this is why you don't mess with recursive commands when sleepy :(.

If I run:  sudo chown -R user:user /   Can I revert it to what it was before I ran it?


I have a continuous function $f:\mathbb{R}\to \mathbb{R}$ which is periodic with period $2\pi$, how to show that there exists a point $x_0\in \mathbb{R}$ s.t $f(x_0)=f(x_0+\pi)$?  I defined the function $g(x)=f(x)-f(x+\pi)$, I want to show that this function vanishes in some point. So I need to find an interval $[a,b]$ where $g(a)g(b)<0$, but how?  I think I had such a question when I took the course but I cannot find my notes from that course.

Prove that for $ f(x+2\cdot\pi)=f(x), x \in \mathbb{R} $, there exists $ x_0 $ so $ f(x_0+\pi)=f(x_0) $.  This is supposed to be question about continuity, but I’m not sure exactly what they mean, perhaps I misunderstood some concept along the way.


I have created a presentation using Beamer template. The presentation is a bit long with lots of references. I believe audience will find more convenience in finding cited references on the same page (at the bottom) rather than looking at the end of the presentation, for example like this    References in standard beamer template appear like this    I couldn't find any beamer template that enables us to show references on the same page. I don't know how can we make such changes. Can anybody point me in the right direction, Thanks in advance

I used \footfullcite to insert two citations in beamer, and got this,     How do I add square brackets to the reference number, and make them become [1][2] instead of 12?    Here is a MWE.  \begin{filecontents*}{References.bib} @article{ahlswede2000network,   title={Network information flow},   author={Ahlswede, Rudolf and Cai, Ning and Li, Shuo-Yen Robert and Yeung, Raymond W},   journal={Information Theory, IEEE Transactions on},   volume={46},   number={4},   pages={1204--1216},   year={2000},   publisher={IEEE} } @article{katti2008xors,   title={{XORs in the air: practical wireless network coding}},   author={Katti, Sachin and Rahul, Hariharan and Hu, Wenjun and Katabi, Dina and M{\'e}dard, Muriel and Crowcroft, Jon},   journal={IEEE/ACM Transactions on Networking (ToN)},   volume={16},   number={3},   pages={497--510},   year={2008},   publisher={IEEE Press} } \end{filecontents*}  %%%   \documentclass[t, 11pt]{beamer} \usetheme{Warsaw}   \usepackage[backend=bibtex]{biblatex} \bibliography{References}  %%%%%%%%%%%%%%%%%%%%%%%%%  \begin{document} \begin{frame}[c]{XOR network coding} XOR network coding \footfullcite{ahlswede2000network} \footfullcite{katti2008xors} \end{frame} \end{document}


I have to make a book cover for my document which must have a png image covering all the height of the left page margin. The rest of the page must have pictures, and text lines centered.  Something like the following coverpage:    How could I do it?  All I can get is to fill with a color the left side of the page   \documentclass[a4paper]{report} \usepackage{tikz}  \title{\tikz[remember picture,overlay] \draw [fill,red!20] (current page.north west) rectangle +(0.33\paperwidth,-\paperheight);% Rather Long Document Title to Show that the Colour is Behind the Title} \author{John Doe}  \begin{document} \maketitle  \end{document}   but not to insert an image.  Thank you very much for your help.

I would like to put a small graphic in the bottom right corner of a the title page of an article. Is there a way to specify a precise location for a graphic on a page (that has text on it)?   I've tried doing it with a \parbox but haven't been able to so far.


I was wondering how can I use code in R to set up a simulation to show that if two random variables each follow a normal distribution with given means and variances, their sum is also normally distributed with a mean equal to the sum of the means of two random variables and variance equal to the variances of the two random variables.

I've been given a problem where I have  $$ X \sim \mathcal{N}(\mu = 2, \sigma^2 = 9) $$  $$ Y \sim \mathcal{N}(\mu = 3, \sigma^2 = 4) $$  Their correlation is $ \rho_{XY} = 0.6 $. First I am asked for the mean and standard distribution of X+Y, which I found as  $$ \mu_{X+Y} = \mu_X + \mu_Y = 2 + 3 = 5 $$  $$ \sigma_{X+Y} = \sqrt{\sigma_{X}^2 + \sigma_{Y}^2 + 2 \rho_{XY} \sigma_x \sigma_y} $$  However, I am also asked what the distribution of $ X + Y $ is, what if $X$ and $Y$ are jointly normally distributed, and what if $X$ and $Y$ are not jointly normally distributed. I am unsure how I would go about determining what the distribution of $X + Y$ is, though I assume that    If $X$ and $Y$ are jointly normally distributed then $X + Y$ is normally distributed If $X$ and $Y$ are not jointly normally distributed then $X + Y$ is not normally distributed   How do I determine what the distribution of $X + Y$ is when I am not told whether they are jointly distributed?    Related  I read the following post, but wasn't sure how to apply what was said to my current problem, if I could at all.


if (std::abs(double1 - double2) < std::numeric_limits<double>::epsilon())   std::cout<<"Equal"; else   std::cout<<"Not equal";  Is this code with modern C++11/14/17/21 is still the way we should compare float and doubles, or now it's ok just to write if (double1 == double2)  And compiler will handle the epsilon issue for us? BTW: is it better to write < or <= when checking against epsilon?

What would be the most efficient way to compare two double or two float values?  Simply doing this is not correct:  bool CompareDoubles1 (double A, double B) {    return A == B; }   But something like:  bool CompareDoubles2 (double A, double B)  {    diff = A - B;    return (diff < EPSILON) && (-diff < EPSILON); }   Seems to waste processing.  Does anyone know a smarter float comparer?


Viewing SE in a desktop browser, I get edit notifications in the inbox:    But in the iOS app (version 1.2.2), I do not see edit notifications in the inbox:

The SE app currently only shows some inbox items:   Answers Comments Chats   When I see those I assume I'm all caught up, but it turns out there are more on the web which aren't displayed in the app:   Bounty expiration Elections Edits on your own posts Maybe others?   I was about to tag this  but realized it's probably intentional.  I imagine the reason for not showing them is because they're not something you can act on from within the app. Bounties can't be offered or awarded1 and elections can't be voted on.  But then again chats can't be replied to either. Badge descriptions can't be viewed (on the Achievements side). Selecting those launches the browser. Why then shouldn't bounties or elections launch the browser too? Hiding them just means I'll miss it if I haven't visited in browser recently.  1 Though accepting answers does award the bounty


I'm looking for a decent all-purpose lens to replace the 18-55mm kit lens on my Canon EOS Rebel XTi (400D). I'd like to keep the price as low as possible but something with a half-decent zoom and IS. Any suggestions?

This is somewhat a follow-up to my . I have browsed through quite a lot of sites including this one for user opinions & reviews of different Canon lenses, but haven't found a comprehensive answer to the possible upgrade paths from the kit lens, particularly since I don't have a specific usage scenario in mind. Here are a few that I have found that answer the question partially:   (Quite old)   (for Pentax though)     (more about the cameras)        For this reason, I thought it would be useful to have a list of sub-$1000 upgrade lenses for the kit lens for APS-C format DSLRs (like the 550D, 60D, 7D etc), as a lot of people are upgrading to DSLRs nowadays. The key points that I seek are:   Pros\cons compared to the kit lens Price Scenarios the lens is suitable for   Keep in mind that it is primarily for APS-C cameras, so, EF lenses meant primarily for the full frame cameras would end up with the magnification factor of 1.6x. Also, this is focused towards hobbyists & amateurs for which reason I've added the sub-$1000 bit.  P.S. This question might be more suited for a wiki like article (albeit with user opinions included)


I have the model  $$y=\beta_1 e^{\beta_2 x}+\beta_3 z+\epsilon$$  where $z$ is an indicator variable. I need to obtain estimates from linear regression to get initial values for the parameters. Then I can do an iterative search to find the best values for each parameter. However, I am having trouble doing this.   For the model  $$y=\beta_1 e^{\beta_2 x}+\epsilon$$  I can simply take the natural log of both sides and run the regression model  $$log(y)=log(\beta_1)+\beta_2 x+\epsilon$$  to get estimates of $\beta_1$ and $\beta_2$ but  $$y=\beta_1 e^{\beta_2 x}+\beta_3 z+\epsilon$$  doesn't appear to be intrinsically linear.   Any suggestions would be greatly appreciated.  Edit:  The data is as follows  df <- read.table(textConnection( 'x y z log_y 0.5 0.68 0  -0.38566 0.5 1.58 1  0.45742 1.0 0.45 0  -0.79851 1.0 2.66 1  0.97833 2.0 2.50 0  0.91629 2.0 2.04 1  0.71295 4.0 6.19 0  1.82294 4.0 7.85 1  2.06051 8.0 56.10 0 4.02714 8.0 54.20 1 3.99268 9.0 89.80 0 4.49758 9.0 90.20 1 4.50203 10.0 147.70 0 4.99518 10.0 146.30 1 4.98566'), header = TRUE)   When the model is just $y=\beta_1 e^{\beta_2 x}$ I get parameters estimates of 0.753 and 0.533 respectively after transforming the data to be linear. In SAS, I used these as the initial values for the new model and let $\beta_3=0$, arbitrarily. Using the Gaussian-Newton method, I got that the convergence criterion was met so it may be a valid approach. The coefficients I obtained in SAS are as follows:

In a set of  that I stumbled upon online, the author discusses a nonlinear regression model, which is linear in some parameters, like this $$ y = \theta_1 + \theta_2\exp \left( {\theta_3x} \right) + \varepsilon $$ and suggests to first perform a nonlinear regression to estimate $\theta_3$, and then use OLS to estimate the other two parameters. I am not very experienced in regression modeling, so please forgive me if I ask a very simple question, but I don't understand how you can do this consistently without also estimating the other 2 parameters? Apparently, there is some trick involved, which I don't understand...  Another question is what happens to the ability to do inferences based on parameter estimates to the complete model if you do the regression in two stages like that?  Many thanks!


During GoF in the Harry Potter series, Profesor Moody       (who is actually Barty Crouch Jr. using Polyjuice Potion)    teaches the kids in his class about unforgivable curses, but then goes into it in detail about them and how they are pronounced, how they work and even how to resist some, like the Imperius curse. He even went as far as saying     "Earn you a one-way ticket to Azkaban. Correct. The Ministry says you are too young to see what these curses do. I say different! You need to know what you're up against. You need to be prepared..."         He also has them practice resisting the imperius curse      "The Imperius curse can be fought, and I’ll be teaching you how, but it takes real strength of character, and not everyone’s got it. Better avoid being hit with it…"   It would seem that teaching students spells to protect themselves from the ambush that you're a major contributor in is not the best plan. That's like arming an enemy country with a missile defense system just before your about to attack them with a missile. And i know that some might say that that he didn't think that Harry would be able to defeat the dark lord anyway but still, why not just teach the 4th year Defense Against the Dark Arts textbook information and be over with it?

Would real Moody have taught 4th year students about Unforgiveable curses the way fake Barty Crouch Moody did?  In other words, did Barty teach about them (leaving aside his hands-on teaching approach) just to satisfy his Death Eater wishes, or did he teach them as part of his cover as Moody impersonator because Moody would have taught about them?


My college currently uses a very old (like 3 years old) openJDK 1.7 distribution. And being a student, obviously I don't have  root privileges. I wanted to use a much later version downloaded a much more recent version from their official website since one of my app (solr) requires it.  I downloaded the JRE 1.8 and checked the interpreter using  saikrishnac@chervil:~/jre18/bin$ ./java -version java version "1.8.0_101" Java(TM) SE Runtime Environment (build 1.8.0_101-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode) saikrishnac@chervil:~/jre18/bin$    It turned out to be just as expected. Now I want to direct all the java calls made by the app to this bin. But, by default, this is what the university has running  saikrishnac@chervil:~$ java -version java version "1.7.0_91" OpenJDK Runtime Environment (IcedTea 2.6.3) (7u91-2.6.3-1~deb8u1) OpenJDK 64-Bit Server VM (build 24.91-b01, mixed mode) saikrishnac@chervil:~$    So, I'm guessing I need to change the JAVA_PATH variable in /etc/profie. But I've only read only access and hence I cannot add the following.  export JAVA_HOME="path" export PATH=$JAVA_HOME/bin:$PATH   The above was suggested at:   Summary  So, is there any workaround for changing the path for just my user account. I mean, when i run java in my account I wish it  executed with the jre18 binary.

The question says it all. I currently use Arch Linux and the zsh, but I'd like a solution that (at minimum) works both on VTs and in xterms and also (hopefully, preferably) will continue to work if I switch distros or shells.  I've heard wildly disparate answers to this question in different distros' docs. Ubuntu says "use .pam_environment". I think in Arch what they recommend depends on your shell. Currently I put everything in  and if a shell doesn't source that for some reason (e.g. bash if .bash_profile exists), I override that by manually sourcing it. But it seems like there must be a better way.


I'm getting 3 year old MacBook Pro with no HD (surplus from the company I work for). I don't have a Mac of any sort to do the install/restore/etc like most other answers to this question assume. I have a Windows PC, and will get a new blank internal SATA drive to put into the MacBook Pro. I also have a 1TB external USB drive, if that helps.  How do I purchase and install the latest compatible OS on this new-old MacBook?

I've just installed a new SSD replacing an HDD in my old (late 2008) iMac. When I switched it on all I got on screen was a question mark.   On the advice of my son I tried cmdR during switch on with no result.   I then tried alt which at least got me a cursor on the screen, but nothing else. Any suggestions? I've got everything backed up on an external Hard Drive, by the way.


I am implementing radio group. When i try to run the app, i get this error  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.RadioGroup.setOnCheckedChangeListener(android.widget.RadioGroup$OnCheckedChangeListener)' on a null object reference.  radio_group_your_choice = (RadioGroup) findViewById(R.id.radio_group_your_choice);         male_radioButton = (RadioButton) findViewById(R.id.male_radioButton);         female_radioButton = (RadioButton) findViewById(R.id.female_radioButton);          radio_group_your_choice.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {             @Override             public void onCheckedChanged(RadioGroup group, int checkedId)             {                 RadioButton radioButton = (RadioButton) findViewById(checkedId);                 gender = radioButton.getText().toString();             }         });  <RelativeLayout                 android:layout_width="fill_parent"                 android:layout_height="wrap_content"                 android:layout_marginTop="0dp"                 android:layout_marginBottom="15dp">                  <RadioGroup                     android:id="@+id/radio_group_your_choices"                     android:layout_width="fill_parent"                     android:layout_height="wrap_content"                     android:orientation="horizontal">                      <RadioButton                         android:id="@+id/delivery_radioButton"                         android:layout_width="wrap_content"                         android:layout_height="wrap_content"                         android:text="Pick Up"                         android:textColor="@color/dark_grey"/>                      <RadioButton                         android:id="@+id/pickup_radioButton"                         android:layout_width="wrap_content"                         android:layout_height="wrap_content"                         android:layout_marginLeft="20dp"                         android:layout_marginStart="20dp"                         android:text="Delivery"                         android:textColor="@color/dark_grey"/>                   </RadioGroup>              </RelativeLayout>

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?


Here is my table:  -- log +----+---------+------------+ | id | user_id |    seen    | +----+---------+------------+ | 1  | 2342    | 1442664886 | | 2  | 3244    | 1442665851 | | 3  | 2342    | 1442711823 | | 4  | 7654    | 1442864219 | | 5  | 3244    | 1442954080 | | 6  | 9984    | 1442984716 | +----+---------+------------+   I want to get the biggest seen time for a specific user as last seen. I can do that by these two queries:  First query:  SELECT seen AS last_seen FROM log WHERE user_id = :id ORDER BY seen DESC LIMIT 1   Second query:  SELECT MAX(seen) AS last_seen FROM log WHERE user_id = :id   Well which one is the standard way? Should I go with which one? Is there any different in the performance?

Out of the following queries, which method would you consider the better one? What are your reasons (code efficiency, better maintainability, less WTFery)...  SELECT MIN(`field`) FROM `tbl`;  SELECT `field` FROM `tbl` ORDER BY `field` LIMIT 1;


If both the asymptotic Variance-Covariance matrix estimators (robust and non-robust) are consistent to the same matrix, i.e., both will have the same efficiency (True?), then what is the advantage of using SE estimators assuming Conditionally Homoskedasticity, when we have Conditionally Homoskedasticity?  Hayashi's Econometrics book states that «the finite-sample properties of an estimator are generally better, the fewer the number of population parameters estimated to form the estimator.», i.e., under conditional homoskedasticity we should use non-robust estimators. I understand that with the robust estimator we estimate more population parameters. But what are these properties that Hayashi speaks of? and how can we prove that they are better?  Any help would be appreciated.

I know that GLS estimators only have exact distributions asymptotically, so the efficiency gains in finite samples are not all that clear. But otherwise, I'm struggling on how to attack this discussion.


I'm trying to bind the command parameter in XAML for a RelayCommand<MessageTokens> as below, where MessageTokens is an enum   public ICommand OpenInvoiceWindowCommand         {             get             {                 return _openInvoiceWindowCommand ??                        (_openInvoiceWindowCommand = new RelayCommand<MessageTokens>(OpenInvoiceWindow, prm => CanExecuteOpenInvoiceWindowCommand));             }         }   The XAML is:    <Controls1:RadMenuItem Command="{Binding SupplierInvoiceViewModel.OpenInvoiceWindowCommand}" CommandParameter="{Binding Source={x:Type ShipmentDetails:DebitInvoiceViewModelBase}, Path=MessageTokens.SupplierInvoice}" Header="Register a supplier's invoice"/>   Using Telerik's RadGridView the code crashes with      at GalaSoft.MvvmLight.Command.RelayCommand`1.CanExecute(Object parameter)    at Telerik.Windows.Controls.RadMenuItem.CanExecuteApply() in c:\Builds\WPF_Scrum\HotFix_2010_Q3\Sources\Development\Controls\Navigation\Menu\RadMenuItem.cs:line 2105    at Telerik.Windows.Controls.RadMenuItem.ChangeCommand(ICommand oldCommand, ICommand newCommand) in c:\Builds\WPF_Scrum\HotFix_2010_Q3\Sources\Development\Controls\Navigation\Menu\RadMenuItem.cs:line 2124    at Telerik.Windows.Controls.RadMenuItem.OnCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) in c:\Builds\WPF_Scrum\HotFix_2010_Q3\Sources\Development\Controls\Navigation\Menu\RadMenuItem.cs:line 1623    at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)    at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)    at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)    at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)   etc.  If I change the parameter to RelayCommand<string> instead of RelayCommand<MessageTokens> the code runs fine.  I'm loathe to do this since I lose all the benefits of strongly typing my parameters.  I suspect that I am not declaring the enum properly in XAML. I've tried     CommandParameter = "<fullpath>..MessageTokens.SupplierInvoice>"   but that gives an InvalidCastException in MVVMLight.  Does anyone have any suggestions?  Many thanks Jeremy     Edited with the solution   The issue was because I wasn't properly referring to the inner class in the CommandParameter binding with the + sign.  the correct XAML should be:  <Controls1:RadMenuItem Command="{Binding SalesInvoiceViewModel.OpenInvoiceWindowCommand}" CommandParameter="{x:Static local:DebitInvoiceViewModelBase+MessageTokens.SalesInvoice}" Header="Raise a sales invoice"/>

I want to pass an enum value as command parameter in WPF, using something like this:  <Button      x:Name="uxSearchButton"      Command="{Binding Path=SearchMembersCommand}"      CommandParameter="SearchPageType.First"     Content="Search"> </Button>   SearchPageType is an enum and this is to know from which button search command is invoked.  Is this possible in WPF, or how can you pass an enum value as command parameter?


I hate change for change sake.  My old Ubuntu, no longer supported, had buttons at the top left for applications, places, and system.  It was a good system that worked well for me. How can I set up the same thing on Ubuntu 12.04.4.

I'm used to GNOME Classic and personally don't want to change to anything else, but it seems there is no more GNOME Classic in the Oneiric release. After apt-get installed gnome-session and all, though there comes back the GNOME Classic option in the session listbox, however, after logged in, it seems not the expected one.  There is no System menu in the top bar, and I couldn't customize panels at all. I want to change the appearance(theme), but I can't find Appearance menu at all. And much more differences to my previous experience of GNOME classic shell.    There are multiple valid answers for this question spanning over several versions of Ubuntu. For your convenience an index of each below:    and up      &