Could anyone please help me identify this creature? It can fly and seems to like crawling as well. It has mandibles that are beetle-like.  Approximately 3cm/2inch. Location: KwaZulu Natal, South Africa

I saw this insect near a beach in Corsica France:


I found the Req of the whole circuit at first, then tried re-assembling the circuit and still I couldn't get the right answer.  Any idea on how I should proceed in this exercise?    I'm not looking for any answers, just a walkthrough.  Step 1:         – Schematic created using   Step 2:          Step 3:

Let's say R = 49 ohms, and we want to find Req between a and d, how do we do that? Do we have to find Req for the whole circuit?


Whenever I google for Lubuntu, lubuntu.net is always appear on the top result. I thought that this was the official site (wasn't sure about this).   However, I've just noticed that there are two sites for Lubuntu. lubuntu.net vs lubuntu.me  only offers older version 19.04 while  offers latest version which is 20.10. Are they from similar or different team? Which one is the official site for Lubuntu?

There are two totally different websites offering Lubuntu:      What is their difference?


I was playing Minecraft and then I changed my skin. It said that I can migrate my old Minecraft account into a Mojang account, so I did.   However I cannot log in anymore. Then after 5 tries of the same thing I got in but couldn't play multiplayer because it says I wasn't authorized. Is it because Microsoft bought Mojang? Because I fully bought Minecraft a while ago.

So I paid for a minecraft account and everything but when I try to log in it says that I don't have a username. Is it an email or an email that you've made just for this account?


Is there a simple method to find or estimate how large  $$\lfloor \lg{n!\rfloor}$$ is ? I'd like to find (or estimate) how much digits $2017!^{2017}$ has, or how much is big that number .     I tried for some little number and general form of $$n!^{n}=\overline{a_k...a_4a_3a_2a_1} \\ k=?$$ so  I took logarithm of $n!^{n} \mapsto n\log(n!) $.  It is easy when $n$ is little number , but when go for a large number ...what we can do  ?  My question can be translate as $$n\sum_{i=1}^{n}\log(i)= ?$$

Suppose we want to show that $$ n! \sim \sqrt{2 \pi} n^{n+(1/2)}e^{-n}$$  Instead we could show that $$\lim_{n \to \infty} \frac{n!}{n^{n+(1/2)}e^{-n}} = C$$ where $C$ is a constant. Maybe $C = \sqrt{2 \pi}$.   What is a good way of doing this? Could we use ? Or maybe take the log of both sides (e.g., compute the limit of the log of the quantity)? So for example do the following $$\lim_{n \to \infty} \log \left[\frac{n!}{n^{n+(1/2)}e^{-n}} \right] =  \log C$$


I have the following tex file;  \documentclass[a4paper]{article} \usepackage{amsthm} \usepackage{thmtools} \usepackage[hidelinks]{hyperref} \newtheorem{thm}{Theorem} \begin{document}  \begin{thm}\label{thm1} Blah. \end{thm}  Consider \autoref{thm1}.  \end{document}   With this set up, \autoref{thm1} prints "Theorem 1", but if I disable thmtools, it only prints "1". I was led to believe that \autoref is part of hyperref and should not require thmtools. Where am I going wrong? Is there a better way to do this?

I have some own theorem environments. And my theorems are numbered like the chapter. Now I would like to use autoref with that. But it does not work like it is described here () with aliascnt. So how can I get that?  \documentclass[ngerman,halfparskip,12pt,pointednumbers]{scrreprt} \usepackage{babel} \usepackage[utf8]{inputenc}  \usepackage[T1]{fontenc}  \usepackage{amsmath,amsfonts,amssymb,amsthm,bbm} \usepackage{hyperref} \newtheoremstyle{absatz}     {17pt}{10pt}{}{-1pt}{\scshape\bfseries}{.}{\newline}{}  \theoremstyle{absatz}  \newtheorem{satz}{Satz}[chapter] \newtheorem*{satz*}{Satz} \newtheorem{lemma}[satz]{Lemma} \newtheorem{corollar}[satz]{Korollar}   %\renewcommand*{\theoremautorefname}{Satz} \begin{document} \begin{satz} \label{Satz} text text theorem \end{satz}   In \autoref{Satz} we have shown... \end{document}


The sentence in question is "I had known (who/whom) my opponent was".  Would you use who or whom in this context, and why?  Thanks.

I can never figure out whether I should use who and whom. Most people use who for both colloquially, but some people say this is not correct.  What’s the rule for using who and whom correctly?


I am interested in functions of the form $\psi: F^n \to \mathbb{R}^+$, where $F$ is a finite field, that have norm-like properties, e.g., $\psi(x+y) \le \psi(x) + \psi(y)$. Does anybody know if there is any literature on this area?

Normed vector spaces are typically defined over the reals or complex numbers.  Is there any "standard," well-behaved construction that generalizes this to a vector space over a finite field, such as $\Bbb F_2$?  I'm looking for something kind of like the class of $\ell_p$ norms, except designed with finite fields in mind.  Ideally, something that has deep fundamental properties making it well-behaved in the same way that the Euclidean norm is.


I am getting "you don't have enough free space in /var/cache/apt/archives/.I have tried apt-get clean ,apt-get autoclean,apt-get autoremove but nothing works for me.

When I run the command to install the package solr-jetty, I am told   You don't have enough free space in /var/cache/apt/archives/   Here's the result of the df -H command:    I have installed Ubuntu with VirtualBox on my Mac.  How can I fix this problem?


For a long time I've felt that the search for foundations in mathematics doesn't have an answer, that it is almost like physics where you can keep asking where things come from.  However, is this not the case? People say that set theory is the/one foundation for mathematics, but set theory uses logic. Moreover, in logic, and here is my largest concern, we define things like strings of characters and statements with truth value.  These things don't appear to require any other mathematical objects, however it seems somewhat non-rigorous to introduce strings and truth values and characters. Is there a chicken-and-egg issue somewhere here, are these ideas well-formulated, should I be confused? In what sense is set theory the foundation of mathematics?

I am trying to understand what mathematics is really built up of. I thought mathematical logic was the foundation of everything. But from reading a book in mathematical logic, they use "="(equals-sign), functions and relations.  Now is the "=" taken as undefined? I have seen it been defined in terms of the identity relation.  But in order to talk about functions and relations you need set theory.  However,  seems to be a part of mathematical logic.  Does this mean that (naive) set theory comes before sentential and predicate logic? Is (naive)set-theory at the absolute bottom, where we can define relations and functions and the eqality relation. And then comes sentential logic, and then predicate logic?  I am a little confused because when I took an introductory course, we had a little logic before set-theory. But now I see in another book on introduction to proofs that set-theory is in a chapter before logic. So what is at the bottom/start of mathematics, logic or set theory?, or is it circular at the bottom?  Can this be how it is at the bottom?  naive set-theory $\rightarrow$ sentential logic $\rightarrow $ predicate logic $\rightarrow$ axiomatic set-theory(ZFC) $\rightarrow$ mathematics  (But the problem with this explanation is that it seems that some naive-set theory proofs use logic...)  (The arrows are of course not "logical" arrows.)  simple explanation of the problem:  a book on logic uses at the start: functions, relations, sets, ordered pairs, "="  a book on set theory uses at the start: logical deductions like this: "$B \subseteq A$", means every element in B is in A, so if $C \subseteq B, B \subseteq A$, a proof can be "since every element in C is in B, and every element in B is in A, every element of C is in A: $C \subseteq A$". But this is first order logic? ($(c \rightarrow b \wedge b \rightarrow a)\rightarrow (c\rightarrow a)$).  Hence, both started from each other?


I have made a human model with a color map, and I want to paint my makeup with different IOR and other values on different map so it won't mess with the skin detail. Is there any way to make a mask so that I can paint a makeup color map that also become a mask of a shader?

I'm designing this animal-type creature, and want to add a transparent .png image to its face with the face features (object has a subsurf). On the left is the image with the features, on the right is the part of the object where I want it to be.    I tried to import the image as a plane, but matching the shape of the plane with the face didn't work, and the lines of the face left shadows on the head, and could be seen as a different object from some angles (although it's the closest I've gotten yet). It looked like this:    So , I tried selecting the faces of the head that the features should go over, and create a new material for it. Unfortunately, since the .png is transparent, the result produced was this:    (where it's impossible to tell the transparency from a black background default color, and where I wouldn't know where to start to adjust size and position).  I also tried UV mapping, but then the whole object became black with the features repeated all over.   Is it something I have to go into Nodes for? I'm kind of stuck here. Creating a new material and applying it is simple, but applying a material that is an image is a bit more complex it seems... Ideally, I would reproduce the same technique for the adhesive bandage on its arm (seen on the right of image 1).


Im writing a paper using biblatex where I want to make it easier for the reader to check the name and author from bibliography in the same page, up to now i have been using \cite go get the references from the bibliography as a [1] and \footnote as intended to write text at the bottom of the page,      This is the note\footnote{content} and this is the cite \footcite{Wuldart}.   Whenever i use a footnote and a footcite I get something like this and of course the numbers reset every page    I actually want the  \footcite command to show     [Number at bibliography] [Author] [Title]   and something like this should come out at the foot of the page     Notice how footnote wasnt affected by the change, Im trying to find a way to redefine footnote to do this,  this way the reader doesnt have to move all over the document just to check the name of the source and he will only do it if he actually wants to review the complete information/url of the source   Im currently using   \usepackage[backend=biber, style=authortitle, citestyle=reading  ]{biblatex}    However i lack the knowlege to redefine the footcite to do what Im loking for

I've started putting into practice the answer to . Yet I would like to change this so that there are brackets around the citations:   in the superscript in text,     in the superscript in footnote,  in the bibliography.   I've managed to get the first one and the last one working. The second one however, I don't know how to do this.   Note that I mainly write in english and in dutch, so I don't think there is much babel interference.  Also, would there be a way to order the footnotes so that first all ''normal'' \footnote{} are printed and below that all \sfcite{} citational footnotes (per page that is)?  Here's what I've managed to concoct:  \documentclass{article} \usepackage[english]{babel} \usepackage[pdfborder={0 0 0}]{hyperref} \usepackage[citestyle=numeric-comp,sorting=none,hyperref]{biblatex} \usepackage{filecontents}  % No brackets around the number of each bibliography entry \DeclareFieldFormat{labelnumberwidth}{\textbf{[#1]}}  %--------------------------------------------------------------- % Essentially verbatim from Joseph Wright % http://www.texdev.net/2010/03/08/biblatex-numbered-citations-as-footnotes/ \makeatletter \ExecuteBibliographyOptions{citetracker,sorting=none}  \DeclareCiteCommand{\notefullcite}[\mkbibbrackets]     {\usebibmacro{cite:init}%         \usebibmacro{prenote}}     {\usebibmacro{citeindex}%         \usebibmacro{notefullcite}%         \usebibmacro{cite:comp}}     {}     {\usebibmacro{cite:dump}%         \usebibmacro{postnote}}  \newbibmacro*{notefullcite}{%     \ifciteseen         {}         {\footnotetext[\thefield{labelnumber}]{%             \usedriver{}{\thefield{entrytype}}\addperiod}}}  \DeclareCiteCommand{\sfcite}[\cbx@superscript]%     {\usebibmacro{cite:init}%         \let\multicitedelim=\supercitedelim         \iffieldundef{prenote}         {}         {\BibliographyWarning{Ignoring prenote argument}}%     \iffieldundef{postnote}         {}         {\BibliographyWarning{Ignoring postnote argument}}}     {\usebibmacro{citeindex}%         \usebibmacro{sfcite}%         \usebibmacro{cite:comp}}     {}     {\usebibmacro{cite:dump}}  \newbibmacro*{sfcite}{%     \ifciteseen         {}         {\xappto\cbx@citehook{%             \noexpand\footnotetext[\thefield{labelnumber}]{%             \fullcite{\thefield{entrykey}}\addperiod}}}}  \newrobustcmd{\cbx@superscript}[1]{%     \mkbibsuperscript{[#1]}%     \cbx@citehook     \global\let\cbx@citehook=\empty} \let\cbx@citehook=\empty \makeatother %---------------------------------------------------------------  \begin{filecontents}{\jobname.bib} @article{ref1,     hyphenation = {american},     title = {Natural Products as Sources of New Drugs over the Last 25 Years},     author = {Newman, D.J. and Cragg, G.M.},     journal = {J. of Nat. Prod.},     volume = {70},     number = {3},     pages = {461--477},     year = {2007}} @article{ref2,     hyphenation = {american},     title = {Natural products as leads to potential drugs: an old process or the new hope for drug discovery?},     author = {Newman, D.J.},     journal = {J. of Med. Chem.},     volume = {51},     number = {9},     pages = {2589--2599},     year = {2008}} @online{ref3,     author = {Quintin, C.},     title = {Les eponges},     url = {http://christophe.quintin.pagesperso-orange.fr/Liste_Doc.html},     urldate = {2009-05-03} } \end{filecontents}  \addbibresource{\jobname.bib}  \begin{document} First citation.\sfcite{ref1,ref2} Some text\footnote{A footnote}.   \pagebreak Second citation\sfcite{ref1}, second citation\sfcite{ref2}, first citation.\sfcite{ref3} \printbibliography \end{document}


I am trying to turn OFF case assignment rules on before case update. However, it seems they are still firing on any field update and assigning the owner to some default user.   Trigger:  trigger TurnOffAssignmentRule on Case (before update) {      List<ID> caseIDs = new List<ID>();       for (Case c : Trigger.New){          caseIDs.add(c.Id);          }       if(caseIDs.size() > 0) {      CaseHelper.updateOwnership(caseIDs);      }  }    Class:  public class CaseHelper {      public static void updateOwnership(List<Id> caseIDs) {          Database.DMLOptions dmo = new Database.DMLOptions();          dmo.EmailHeader.triggerUserEmail = false;          dmo.assignmentRuleHeader.useDefaultRule = false;         List<Case> casesToUpdate = [select id from case where id in :caseIDs];           Database.update(casesToUpdate, dmo);     }  }   I am not sure am taking right approach. Any suggestions?

I have a condition where I need to disable standard Lead Assignment Rules if certain criteria are met.   if(emailWithAccIdMap.containsKey(ledRec.Email) && emailWithAccIdMap.get(ledRec.Email) != null && !openOppMap.isEmpty() && openOppMap.get(emailWithAccIdMap.get(ledRec.Email)) != null && openOppMap.get(emailWithAccIdMap.get(ledRec.Email)).Owner.isActive ==true){                     ledRec.Status = 'Duplicate';                     System.debug('Changing the Status');                     //then assign the original lead owner to new lead owner                     ledRec.OwnerId = openOppMap.get(emailWithAccIdMap.get(ledRec.Email)).OwnerId;                     ledRec.Account_Name__c = openOppMap.get(emailWithAccIdMap.get(ledRec.Email)).AccountId;                     ledRec.Field_for_Lead_Workflow__c = true;                     Database.DMLOptions dmo = new Database.DMLOptions();                     dmo.assignmentRuleHeader.useDefaultRule = false;                     ledRec.setOptions(dmo);                     //since owner is assigned, it shouledRec not pass through round robin                     ledRec.checkAssignment__c = false;  }   This is my code snippet which is running on before insert. The control is entering the IF condition as the debug statement is getting printed. Yet, the owner assigned through this snippet is being overridden by the assignment rules.  I also tried executing this in after insert trigger context but it did not work. Can somebody tell me what I'm doing wrong?


Problem: Given: q is an odd squared number - show that: $q\equiv_8 1$  My assumption: $\forall q\in N:\exists a \in Z: a =1\pmod{2}$ and $a^2=q$.  Then I tried to show that it's only true satisfyingly if $\mathrm{gcd}(q,8)\mid 1 \leftrightarrow x\cdot q+y\cdot 8=1$.  But I don't know how to show that it is true for all numbers $q$.  All hints are welcome.

How can we prove that every odd perfect square is congruent to $1$ modulo $8$?


In the following sentence:     "When I visited my old school after so many years, it looked completely different in the classrooms and the backyard /from what/to what/than/ it had been when I was a little boy.">       Are the three options acceptable in spoken English ?

As someone who learned English later on in life, I was taught that different from is the correct grammar to use: this is different from that. However, it seems these days everyone uses different than instead. I know it's incorrect usage, but does the language evolve if the majority wins?  Edit: Some commented different than is American English and different from is British English, both are OK. IMO, this isn't like color versus colour, though.   Than is used after a comparative adjective, e.g. taller than, whiter than. The word different isn't a comparative adjective, unless used in more different than. Logically, it makes no sense to say different than.


I don't know how to prove the following.  Let $n$ be an odd natural number with $t$ different prime divisors. Then the polynomial $X^2-1$ has exactly $2^t$ roots.  Own tries  First of all: $X^2-1=(X-1)(X+1)$. We say that $a \in \{1, 2, \cdots, n \}$ is a root if and only if $(a-1)(a+1)=kn$ for some integer $k$. Now observe that $p|(a-1) \iff p\nmid(a+1)$, except when $p=2$. If $a$ is odd, $2$ divides both $a+1$ and $a-1$. If $a$ is even, $2$ divides neither. Luckely $n$ is odd. This means that a prime divisor $p$ from $n$ only can appear in maximal one of the numbers $a+1, a-1$.   It looks like we only need to prove that there exists $k \in \mathbb{Z}$ so that $p$ appears in at least  one of these numbers: $kn+a-1, kn+a+1$, because, be previous observations, there are exactly $2^t$ was to "arrange" prime divisors in the factorisation of $\bar{a}-\bar{1}$ and $\bar{a}+\bar{1}$. Is this correct?

I need to solve this equation:  $x^2 = 1$ in the ring $\mathbb{Z}/n \mathbb{Z}$.  I know  that  $(n - 1)(n - 1) \equiv 1 \pmod n$, in general $(n-a)^2 \equiv a^2 \pmod n$.  I also know that for $p$ prime all elements of $\mathbb{Z}_p$ are invertible and here $1$ and $p-1$ are their own inverses.  Could you tell me what other solutions there are to this equation?


I am about to start writing my thesis in latex, but seem to have some trouble implementing bibliography. In the simple document below, I am just practicising the basics. But I seem to keep failing at implementing bibliography in the document. I keep getting the (blue colored) errors 'Citation Schoen2013 on page 6 undefined', 'Empty bibliograph' and 'there were undefined references'. I created a document 'literature.bib' in notepad++ and saved in the folder 'bib'. The .bib document has the content below. Any ideas?  @article{schoen2013, author  = {Torsten Schoen and Co Author}, title   = {Ten things you better not say to your wife}, journal = {Optimizing Husbands}, volume  = {21}, year    = {2013}, pages   = {85--91},  }  \documentclass[a4paper,12pt]{report} \usepackage{graphicx} \usepackage{biblatex} \usepackage{algorithm} \addbibresource{bib/literature.bib} \begin{document}[a4paper,12pt]  \chapter*{Declaration}  \chapter*{Abstract}  \chapter*{List  of abbrevations and symbols}  \tableofcontents  \chapter{Introduction}  \section{Insurance industry}  \includegraphics{fig/circle}  \section{IBNR Claims and Claims Reserving}  \section{Link with GLM}   We refer to \cite{schoen2013}  \section{Robustification and Problems}  \section{Applications}  \chapter{Body}  \chapter{Conclusion}  \printbibliography  \end{document}

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


What is the simplest and reasonably efficient way to slice a list into a list of the sliced sub-list sections for arbitrary length sub lists?  For example, if our source list is:  input = [1, 2, 3, 4, 5, 6, 7, 8, 9, ... ]   And our sub list length is 3 then we seek:  output = [ [1, 2, 3], [4, 5, 6], [7, 8, 9], ... ]   Likewise if our sub list length is 4 then we seek:  output = [ [1, 2, 3, 4], [5, 6, 7, 8], ... ]

I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but this is potentially extremely expensive.  I was wondering if anyone had a good solution to this for lists of any length, e.g. using generators.  I was looking for something useful in itertools but I couldn't find anything obviously useful. Might've missed it, though.  Related question:


I came across this question when trying the intanceof() operator. This code returns true when working with String Objects:   var aStringObj = new String('String'); console.log(typeof aStringObj); // object console.log(aStringObj instanceof String); // true    ... and returns false with Literal Strings, like so:   var aLiteralString = "Test literal"; console.log(typeof aLiteralString); // string console.log(aLiteralString instanceof String); // false    According to , this operator tests presence of constructor.prototype in object's prototype chain, and for both; the aStringObj and aLiteralString, the .constructor.prototype are the same:   var aStringObj = new String('String'); console.log(aStringObj.constructor.prototype);// String {length: 0, [[PrimitiveValue]]: ""}  var aLiteralString = "Test literal"; console.log(aLiteralString.constructor.prototype); // String {length: 0, [[PrimitiveValue]]: ""}    Does this mean that primitive values are not instances of any prototype? And literal strings don't have a known constructor? The more I study JS the more dumb questions arise to my head. Thanks in advance.

"foo" instanceof String //=> false "foo" instanceof Object //=> false  true instanceof Boolean //=> false true instanceof Object //=> false false instanceof Boolean //=> false false instanceof Object //=> false  12.21 instanceof Number //=> false /foo/ instanceof RegExp //=> true  // the tests against Object really don't make sense  Array literals and Object literals match... [0,1] instanceof Array //=> true {0:1} instanceof Object //=> true  Why don't all of them? Or, why don't they all not? And, what are they an instance of, then? It's the same in FF3, IE7, Opera, and Chrome. So, at least it's consistent.


What are the questions in the 'featured' tab on the Stack Overflow Questions page?  How does a question become 'featured'? Is it just a list of questions with active bounties?

It's possible to offer and award bounties of reputation on questions.   What is a bounty? How can I find questions that have a bounty attached? How do I start a bounty? When can I start a bounty? Why is the system requiring me to choose a bounty amount that's higher than the minimum? Can I use Markdown formatting in the bounty remarks? Can I edit the remark? How long is the bounty period? How do I award a bounty? Can I award a bounty to my own answer? Can I award a bounty to an old answer? If I offer a bounty on someone else's question, can I award the bounty to their answer? After awarding the bounty, can I remove it or move it to another answer at a later time? What happens if there's no answer after the bounty period? What happens if I feel my question is still unanswered? What is automatic awarding? Are bounty awards exempt from the 200 points/day reputation limit? How does Community Wiki mode affect bounties? How does user deletion or post dissociation affect bounties? Can I award a bounty to an answer from a deleted user or one where the author was dissociated? Can I offer a second bounty after the first one has expired? Can I raise my bounty? What happens if a bounty question is closed or deleted? Why can't I vote to close or migrate a bounty question? What happens if I delete my account while I have an active bounty? Do I keep an awarded bounty when I delete my answer? What happens if a question where I awarded a bounty later gets deleted or migrated? Can I cancel my bounty? Can I affect / divide / share part of my bounty to two (or more) users? How many outstanding bounties can a single user have?      See also:  in the Help Center


I am rendering a multiple-views of an object in blender-python API. I am able to render multiple views by moving the camera in a circular path. I would like to know how to get the camera poses for the rendered multiple views. I would want to save the camera pose information for each rendered view. I am new to blender and blender-python. Any quick help is appreciated? Thank you!

I have a camera with an object constraint to track an empty plain axes. I want to get the camera's current rotation, since when the axes move, or when the camera changes location, the camera rotates in order to track the axes.  however, when I read the value using  C.scene.camera.rotation_euler, the values never change, even though the camera clearly has rotated in order to follow the axes.  >>> C.scene.camera.rotation_euler Euler((-0.2408553957939148, -0.0, 0.0), 'XYZ')   How do I get the correct values of the camera rotation?


I'm drawing this plot via overleaf. This is the code: \begin{figure} \resizebox{0.5\textwidth}{!}{%   \begin{tikzpicture}     \begin{axis}[         symbolic x coords={FasterRCNN,Yolov5,EfficientDet,Ensemble},         xlabel=Detector,         ylabel=mAP,         xtick=data,         legend style={at={(0.75,0.35)},             anchor=north},         ]         \addplot [red,mark=*, nodes near coords,every node near coord/.append style={xshift=19pt,yshift=-7pt,anchor=east,font=\footnotesize}, ultra thick]         coordinates {(FasterRCNN,0.210) (Yolov5,0.248)             (EfficientDet,0.256) (Ensemble,0.259)};         \addplot [green,mark=square,nodes near coords,every node near coord/.append style={xshift=19pt,yshift=-7pt,anchor=east,font=\footnotesize}, ultra thick]         coordinates {(FasterRCNN,0.246) (Yolov5,0.263)             (EfficientDet,0.276) (Ensemble,0.285)};         \addplot [blue,mark=star,nodes near coords,every node near coord/.append style={xshift=-6pt, font=\footnotesize}, ultra thick]         coordinates {(FasterRCNN,0.269) (Yolov5,0.278)             (EfficientDet,0.281) (Ensemble,0.292)};         \legend{None, Resnet50, EfficientNet}     \end{axis} \end{tikzpicture}} \caption{Evaluation of combination of classifier and detector in the proposed framework.} \label{fig:mota_idf1} \end{figure}  My question is how to configure amount of the number of digits after the comma ? In my case, I want it show 3 digits after the comma, eg, 0.281 instead of just 0.28 Many thanks

Is there a way to specify that node near coords labels should use 1 rather than 2 decimal places? For example, in the code below, Singapore is printed with 8.1 (correct), but Niger is printed with 46.12 (wrong) when I want it instead to be 46.1 (correct).  \documentclass{standalone}  \usepackage{pgfplots} \pgfplotsset{compat=1.12}  \begin{document} \begin{tikzpicture} \begin{axis}[     xlabel={Birth rate (births/1,000 population)},     symbolic y coords={Niger,United States,Singapore},     ytick=data,     xbar,     nodes near coords, nodes near coords align={horizontal}]    \addplot coordinates {     (46.12,Niger)     (13.42,United States)     (8.10,Singapore)   };  \end{axis} \end{tikzpicture} \end{document}


In the context of dimensionality reduction one often uses word embedding, which seems to me a , which rather stands out compared to the rest of the discussion, which in case of PCA, MDS and similar methods is just the basic linear algebra. Yet, I would rather avoid using/interpreting this term too loosely. So, what embedding really is: the low-dimensional subspace hidden within a bigger one? The projections of the data vectors onto this subspace? The projection operator mapping the higher-dimensional space onto the lower-dimensional one, as suggested  and ? Something else? Thank you for clarifications and examples.

In ML the term "embedding" gets tossed around a lot and the term basically means the construction of a function that takes a high-dimensional vector to a low-dimensional vector in such a way that the high-dimensional vector can be recovered by the low-dimensional vector. (...at least in the case of autoencoders, not sure if word embedding cares about reconstructing the word.) Embedding was also a word that I encountered in topology and differential geometry.  Does there exist any correspondence between the usage of these terminologies between math and ML?


I'm learning Python3. I can't solve a problem... Please help me. I could input 2 different strings(One is consisted with string another is consisted with float). I'd like to make a dictionary from 2 different lists. I made first one for key, another is for value.  input1 = list(map(str, input().split())) input2 = list(map(float, input().split()))  # output = dict(zip(input1), (input2)) output = dict((input1, input2) for (input1[i], input2[i]) in range(0, len(input2))) print(output)   Don't care too much that comment(#) I found a post may help my probelm from stack overflow.   I did my best but I coudn't solve this...(New one below # comment, It is what I tried to reading that post)  Thanks to read my question!

Imagine that you have the following list. keys = ['name', 'age', 'food'] values = ['Monty', 42, 'spam']  What is the simplest way to produce the following dictionary? a_dict = {'name': 'Monty', 'age': 42, 'food': 'spam'}


I find this example in Topology 2nd ed. by James Munkres P.139 Example 4  Let $X = \{x \times y \mid x^2+y^2\leq1\}$, $X^*$ be the partition of X consisting of all the one-point sets $\{x \times y \}$ for which $ x^2+y^2< 1 $ along with the set $S^1=\{\{x \times y\}\mid x^2+y^2=1\}$  Show that $X^*$ is homeomorphic to $S^2$ where $S^2=\{(x,y,z) \mid x^2+y^2+z^2=1\}$   $X^*$ just likes gluing the boundary together to form a sphere.So I identify $\{0 \times 0\}$ to $(0,0,-1)$, which means I match the centre to the south pole. Then I divide the disc into two parts: For $x^2+y^2=r^2$ where $r<0.5$, I map $(x,y)$ maps into $(\alpha x,\alpha y, r)$ where $\alpha ^2 = \frac{1-r^2}{r^2}$ . It means I map the inner ball into southern hemisphere. I do the similar thing for the remaining annulus. Finally, I map the $S^1$ into the north pole$=(0,0,1)$  Am I doing it right?  Thank you!

This is an example from Munkres's Topology (Example 4 in Section 22 titled "The Quotient Topology", 2nd edition).  Example 4: Let $X$ be the closed unit ball $$\{ x \times y \mid x^2 + y^2 \le 1\}$$ in $\mathbb{R}^2$, and let $X^{\ast}$ be the partition of $X$ consisting of all the one-point sets $\{ x \times y \}$ for which $x^2 + y^2 < 1$, along with the set $S^1= \{ x \times y \mid x^2 + y^2 = 1 \}$. Typical saturated open sets in $X$ are pictured by the shaded regions in the figure below. One can show that $X^{\ast}$ is homeomorphic with the subspace of $\mathbb{R}^3$ called the unit 2-sphere, defined by $$S^2 = \{ x \times y \times z \mid x^2 + y^2 + z^2 =1 \}.$$  I am confused about two points in the example.  Problem 1: About the saturated open sets in $X$. In the example, the typical ones are pictured by the shaded regions ($U, V$) in the figure. However, I am not sure whether the boundaries (visually, by picture) of $U$ and $V$ are included. Particularly, there are two boundaries for $U$. Are they both contained in $U$? And why? Problem 2: How to show that $X^{\ast}$ is homeomorphic with $S^2$? What is the mapping between them?  The following is my understanding:  Solution to problem 1: For $V$, the boundary is not included. For $U$, the outer boundary is included, while the inner one not. Is this solution right?


How do you get installed software like sound recorder to open for use when playing sound or music? For that matter how do get access, like on desk top for any installed software to display icon for use? If this is old question please direct me, new to Ubuntu.

Just installed Ubuntu for the first time... Is there any simple way to browse installed programs?  On Mac there is the Applications top-level folder... here I see Desktop, Documents, Downloads etc but no Apps? That'd be a good idea, no? (is there some way to create this myself?)  On Windows there is the Start menu...  Here it seems like I have to click the 'Dash Home' and then I can see 'Recent Apps' ... I can search for them (I'd rather not)  ...or I can click the ruler/pencil icon at the bottom and see 'Recent Apps' and click to expand 'Installed Apps' ...ok that's all of them - is it possible to get a straight list view instead of the hard-to-scan wrapped rows?  Also, is there any way to get rid of the pointless random selection of 'Apps available for download' at the bottom?


I do know that the probability density function of beta distribution is  $$ \frac{x^{\alpha-1}(1-x)^{\beta-1}} {\displaystyle \mathrm {B}(\alpha,\beta)}\! $$ where  $$ {\displaystyle \mathrm {B} (\alpha ,\beta )={\frac {\Gamma (\alpha )\Gamma (\beta )}{\Gamma (\alpha +\beta )}}} $$  Also, I know that support of a function is the subset of the domain containing those elements which are not mapped to zero. But I don't know how do I go about calculating the support for beta distribution.

Beta regression (i.e. GLM with beta distribution and usually the logit link function) is often recommended to deal with response aka dependent variable taking values between 0 and 1, such as fractions, ratios, or probabilities: .  However, it is always claimed that beta regression cannot be used as soon as the response variable equals 0 or 1 at least once. If it does, one needs to either use zero/one-inflated beta model, or make some transformation of the response, etc.: .  My question is: which property of beta distribution prevents beta regression from dealing with exact 0s and 1s, and why?  I am guessing it is that $0$ and $1$ are not in the support of beta distribution. But for all shape parameters $\alpha>1$ and $\beta>1$, both zero and one are in the support of beta distribution, it's only for smaller shape parameters that the distribution goes to infinity at one or both sides. And perhaps the sample data are such that $\alpha$ and $\beta$ providing best fit would both turn out to be above $1$.  Does it mean that in some cases one could in fact use beta regression even with zeros/ones?   Of course even when 0 and 1 are in the support of beta distribution, probability of observing exactly 0 or 1 is zero. But so is the probability to observe any other given countable set of values, so this cannot be an issue, can it? (Cf.  by @Glen_b).  $\hskip{8em}$  In the context of beta regression, beta distribution is parameterized differently, but with $\phi=\alpha+\beta>2$ it should still be well-defined on $[0,1]$ for all $\mu$.


Assuming  $$e^{x}=\sum_{i=0}^{\infty}\frac{x^i}{i!},$$  show that $e^{x}e^{y}$ = $e^{x+y}$.  I have expanded both but am not sure if I need to multiply the two summations and show that product or if there is a simpler way of showing this.

In order to show $e^{x+y}=e^{x}e^{y}$ by using Exponential Series, I got the following:   $$e^{x}e^{y}=\Big(\sum_{n=0}^{\infty}{x^n \over n!}\Big)\cdot \Big(\sum_{n=0}^{\infty}{y^n \over n!}\Big)=\sum_{n=0}^{\infty}\sum_{k=0}^n{x^ky^n \over {k!n!}}$$  But, where should I go next to get $e^{x+y}=\sum_{n=0}^{\infty}{(x+y)^n \over n!}$.  Thanks in advance.


I am using Ubuntu 14.04 LTS 64 bit and installed the wrong version of Sun/Oracle's Java JDK (32 bit instead of 64 bit) using the   I assume I have to uninstall it now. How can I do that?

I didn't find any related articles about . There are some related articles but they didn't solve the problem.  I installed Oracle JDK tarball file from Oracle site by following this article . It was very helpful. But still I don't know what I should do in order to uninstall Oracle JDK.


I want to create multiple primitives such as spheres via python, but my current approach is too slow:  import bpy import time  t0 = time.time() for i in range(400):     bpy.ops.mesh.primitive_ico_sphere_add(radius=0.5, location=[i * 10, 0, 0])  t1 = time.time() dt = t1 - t0 print(dt)   This code takes about 5 seconds, which is just too slow (why?). Is there a way to make it run faster? I suspect creating the mesh every single iteration might be too slow and there is probably a better way to create multiples copies with the same shared mesh, but only different positions, which might be faster.

In my application I have to create up to some 1000 tetraders (objects with 4 vertices, 4 faces, 6 edges). As input I get only the absolute vertex coordinates for each tetraeder. From the mathematical background I know that all tetraeders are identical but have a different location and rotation which I do not know.  The following code works (Tetra is some class providing the vertex coordinates of an tetraeder and some other informations which is not relevant here):  # object creation def draw_Tetra(Tetra, Faces):       bm = bmesh.new()     V1 = bm.verts.new(Tetra.Vertices[0])     V2 = bm.verts.new(Tetra.Vertices[1])     V3 = bm.verts.new(Tetra.Vertices[2])     V4 = bm.verts.new(Tetra.Vertices[3])      if Faces == True:          bm.faces.new((V1, V2, V3))           bm.faces.new((V1, V2, V4))         bm.faces.new((V1, V3, V4))         bm.faces.new((V2, V3, V4))             else:          bm.edges.new((V1, V2))         bm.edges.new((V1, V3))         bm.edges.new((V2, V3))         bm.edges.new((V1, V4))         bm.edges.new((V2, V4))         bm.edges.new((V3, V4))     name = "T_" + Tetra.Type + "_" + Tetra.pedigree me = bpy.data.meshes.new(name) bm.to_mesh(me) bm.free obj = bpy.data.objects.new(name,me) scene = bpy.context.scene scene.objects.link(obj)   However the script is extremely slow, e.g. to create 5000 tetraeders takes many hours. I think that I have the same problem as discussed here:    The problem is that I do not know how to use "low level code" in this special situation. Can someone give me a tip?


I get the result -2.7755575615628914e-17 when my code 0.3 - 0.2 - 0.1 runs in Google Chrome browser. Why? and what does the wrong result stand for?

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


Ok here's the issue. Normally the Chinese postdocs have to be under 35 years of age plus under 3 years from PhD. However, I am slightly over 3 years from PhD. However, I already will have a one year postdoc experience (currently pursuing) prior to starting a (second) postdoc in China. My age would be around 37 by that time though. So, aren't there any age relaxations for people already having some postdoc experience? By the way, I also have a 2.5 years of University (teaching+research) experience prior to starting my (first) postdoc. This is really an ugly rule if it still doesn't allow any age relaxations provided all the University experience plus a postdoc.

It's been 4 years since my PhD and now I'm applying for a postdoc in China. The Chinese website mentions that the age limit for applicants is 35 years and the applicants must have received their PhD within the last 3 years.  I heard that Chinese universities are strict with age when it comes to postdoc positions. However, they can be more lax on post-PhD experience.


I am trying to install Ubuntu 13.10 32 bit on older PC with only 256MB of RAM but every time it gets to the screen where choice needs to be done between demo and install it just hangs and I can not go any further. Sometimes it hangs even sooner on the purple screen. The mouse get sluggish and clicking on buttons does not do anything. Is it possible to run this OS on this older PC and if so what steps should I take to get it installed?? If I can not use Ubuntu on this PC can someone recommend another Linux OS which can be used?? Just trying to move away from Windows XP.

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


I have a question regarding Atwood's machines. Consider the following machine and text accompanying it:       The tension in the short string connected to $m_1$ is $2T$ because there must be zero net force on the massless left pulley, because otherwise it would have infinite acceleration.    My problem is that I don't see why the net force on the left pulley must be zero, since it means that the acceleration of the left pulley must be zero, although it clearly is moving upwards (and thus accelerating) when the mass $m_2$ is accelerating downwards.

Imagine a massless and frictionless pulley with two weights hanging either side of the pulley by a massless string.    Rather than being fixed to a ceiling, the pulley is being pulled upward by an external force F, with the weights and string still attached.  Due to Newton's 2nd Law,  $\Sigma F_y=F-2T=ma$,  where $T$ is the tension in the string on either side of the pulley and $a$ is the vertical acceleration of the pulley.  Clearly, since there is a net upward force, the pulley itself will accelerate upwards.  But because the $m=0$,   $F-2T=0$.  Does this not then suggest that the pulley has a constant velocity?


Out of curiosity, I just wanted to know: What is the reason that we can't delete more than five answers of our own in a day?  I am aware of the fact that this is a feature of Stack Overflow, but is there any specific reason for such a restriction as I am just trying to delete my own answers, not anyone else's, so shouldn't I have the authority to do so?  I get the point which Mysticial mentioned in comments, but what about the users who have a large number of reputation points, say more than 10k or may be 5k?  Ok I got the point that it is to restrict the rage quitters to delete there good quality answers. But why it is set to 5? As even then also any rage quitter can delete his standard good quality answer also!(Sorry if that is too obvious)  My curiosity becomes more after watching the some good answers(Score of 255) getting detete from this question:-

I'm trying to  when I run into this:     "You have already deleted 5 of your own posts today; further deletes are blocked"      I found conflicting information on this very annoying limit:   This post from May 25, 2010: . This is marked . If this is no longer the case, please edit that question and flag it as . Then , indicates that the problem has risen from the dead -- despite :     Each time that I've seen it (pruning subpar answers), it's been a user who is deleting their own redundant zero-upvote answers. Can you tweak the algorithm slightly so answers with less than one upvote don't count towards tripping this flag?     (Emphasis added.) :     I don't mind it when         cleaning up redundant answers on questions that have multiple alternate good answers   cleaning up old, "less awesome" answers that are no longer reflective of the user's current skill level         (Emphasis added.)     So why do we have barriers in place, to making SO answers less, "less awesome"?      Proposed Solution:  Please let us (¿once again?) delete an unlimited number of our own answers, when they have zero up-votes and are not marked as the answer.  Otherwise, please edit the linked questions to clear up the confusion.


I am new to AES and I am too much confused about the generation of S-box in AES. I don't have any idea of $GF(2)^8$ field and how the things are happening around. Please answer this question with a example in layman language.

I'm trying to understand how the AES S-Boxes are calculated. I understand how the multiplicative inverse is calculated over $GF(2^8)$, but I'm confused by the description of the affine transformation. I haven't been able to Google a good explanation of how the S-Box values are calculated. Can someone explain how this works, starting after the calculation of the multiplicative inverse?


I'm very limited in writing Latex code and I could not find how to solve my problem searching in the forum ou googling around.  My problem: I have to write a document with many algorithms and show both the source code and the final typesetting.  This is a MWE of the result I want:  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{algpseudocode} \begin{document} The code \begin{verbatim} \If{$a > b$}     \State $c \gets a$ \Else     \State $c \gets b$ \EndIf \end{verbatim}  is typeset as  \begin{algorithmic}     \If{$a > b$}         \State $c \gets a$     \Else         \State $c \gets b$     \EndIf \end{algorithmic} \end{document}   However, I don't want to replicate the code of each algorithm, as it makes hard to maintain and leads to inconsistencies.  I'd like to know if there is a way to define a code and render it as an algorithm and as a source code.  Here is an M(non)WE of what I'd like to have:  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{algpseudocode} \begin{document}  \newsamplecode{\ExampleOne}{     \If{$a > b$}         \State $c \gets a$     \Else         \State $c \gets b$     \EndIf }  The code  \begin{Verbatim}     \ExampleOneCode \end{Verbatim}  is typeset as  \begin{algorithmic}     \ExampleOneAlg \end{algorithmic} \end{document}   So far, I'm trying to store the source code and make it available as two distinct macros. It's obviously not working and I'm running out of ideas. Here is what I got:  \newcommand{\newsamplecode}[2]{%     \expandafter\def\csname sc#1\endcsname{#2}     \expandafter\newcommand\csname sc#1verb\endcsname{\verb|#2|} }   This successfully works:  \newsamplecode{codigodez}{     \State Input $s$     \If{$s$}         \State \textbf{say} \textit{ok}     \EndIf }  \begin{algorithmic}     \sccodigodez \end{algorithmic}   But I'm not able to render the source code in any way. I tried to use the xstring package to convert the argument to verbatim and/or to replace \ with \textbackslash. Until now, the internal commands (like \State) seems to be evaluated before any processing I try to apply.  If anyone could point me to a solution, I appreciate.    Edit with my solution  I created a new environment, which saved the code as is, and new commands to input the saved file in distinct context: to typeset as algorithm and to show it verbatim.  \documentclass{article}  \usepackage{algorithm} % numbered algorithms \usepackage{algpseudocode} % algorithmic typeset  \usepackage{tcolorbox} % to save verbatim \usepackage{fancyvrb} % to load verbatim preserving tabs  % environment and commands \newenvironment{definecode}[1]{\begingroup\tcbverbatimwrite{\jobname_code_#1.tmp}}%     {\endtcbverbatimwrite\endgroup} \newcommand{\algcode}[1]{\input{\jobname_code_#1.tmp}} \newcommand{\sourcecode}[1]{\VerbatimInput{\jobname_code_#1.tmp}}  \begin{document}  % a code to be stored \begin{definecode}{mycode} \State $x \gets 1$ \While{$x < 10$}     \State $x \gets x-1$ \EndWhile \end{definecode}   % using the stored code See Alg~\ref{alg:my}.  \begin{algorithm}     \caption{My algorithm.}     \label{alg:my}     \begin{algorithmic}[1]         \algcode{mycode}     \end{algorithmic} \end{algorithm}  And this is the source for Alg~\ref{alg:my}:  \sourcecode{mycode}  \end{document}   I opted to use the commands to detach an "algorithm name" in the code from its actual file name. I know that if I use the same name the file will be overwritten, but I can manage it manually for now.

In (La)TeX documentation and tutorials, it is common to show a snippet of code next to the output it generates. It might be two minipages side by side, or a code listing followed by boxed output, or whatever. For a trivial example, we might see  \[ sin \theta \] next to its output, sin θ  Whenever I've done this, I had to use two copies of the code, e.g., once inside verbatim and once inside a minipage or framed box). This just begs for inconsistencies and maintainability problems, since it's very easy to fix one copy and not the other. So, is there any way to display a bunch of code and to execute (a copy of) it, showing the results?  I'm pretty sure it's not straightforward: the code needs to have different catcodes for reading and displaying, but catcodes get assigned only once, when the text is encountered. But if there's no better way, it should be doable by reading the code verbatim and saving a copy in the .aux file, from where it'll get read and interpreted the next time around. But I've never seen such a thing. Has anyone else here?


I'm currently working on making a basic TextEditor in Java FX but I'm having a bit of difficulty. I am trying to incorporate the MVC development style and using any object of type Document in the model when working with the editor although when I try to save the area of the contents I get a NullPointException when I try set any variables in the when the Document is initialised to null. It works fine with it set to a new document will null parameters though...  Any information on the reasoning for this would be really appreciated!  Edit:   Sorry for the ambiguity, I was meaning in terms of initialising an object that I am trying to then set variables for. I had it initialised to simply null:   Document workingDocument = null    When I changed this to:   Document workingDocument = new Document(null, null);   I understand what creating a new Documents does in terms of memory but not what simply initialising it to null does...

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 am conducting an experiment with a control group and a treatment group. Both groups will take a pre and post treatment depression inventory. What statistical procedure do I use to determine if the treatment reduced depressive symptoms significantly?  T-test or ANOVA, which kind and why?

Imagine the following common design:   100 participants are randomly allocated to either a treatment or a control group the dependent variable is numeric and measured pre- and post- treatment   Three obvious options for analysing such data are:   Test the group by time interaction effect in mixed ANOVA Do an ANCOVA with condition as the IV and the pre- measure as the covariate and post measure as the DV Do a t-test with condition as the IV and pre-post change scores as the DV   Question:    What is the best way to analyse such data?  Are there reasons to prefer one approach over another?


I have a problem with WIFI connection on just installed ubuntu 14.04 . There are no drivers available to update.   lspci gives the following results:   00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b) 00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 0b) 00:14.0 USB controller: Intel Corporation Lynx Point-LP USB xHCI HC (rev 04) 00:16.0 Communication controller: Intel Corporation Lynx Point-LP HECI #0 (rev 04) 00:1b.0 Audio device: Intel Corporation Lynx Point-LP HD Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 1 (rev e4) 00:1c.2 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 3 (rev e4) 00:1c.3 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 4 (rev e4) 00:1c.4 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 5 (rev e4) 00:1d.0 USB controller: Intel Corporation Lynx Point-LP USB EHCI #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation Lynx Point-LP LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation Lynx Point-LP SATA Controller 1 [AHCI mode] (rev 04) 00:1f.3 SMBus: Intel Corporation Lynx Point-LP SMBus Controller (rev 04) 06:00.0 Network controller: Broadcom Corporation BCM43142 802.11b/g/n (rev 01) 07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 07) 08:00.0 3D controller: NVIDIA Corporation GF117M [GeForce 610M/710M/820M / GT 620M/625M/630M/720M] (rev a1)   iwconfig shows :  ppp0      no wireless extensions.  lo        no wireless extensions.  eth0      no wireless extensions.   Please help...

I'm having serious problems installing the Broadcom drivers for Ubuntu. It worked perfectly on my previous version, but now, it is impossible.   What are the steps to install Broadcom wireless drivers for a BCM43xx card?  I'm a user with no advance knowledge in Linux, so I would need clear explanations on how to make, compile, etc.    lspci -vnn | grep Network showed:   Broadcom Corporation BCM4322 802.11a/b/g/n Wireless LAN Controller [14e4:432b]      iwconfig showed:  lo        no wireless extensions. eth0      no wireless extensions.   NOTE: Answer below is updated every time new information is added and confirmed working.


A couple of recent blog posts pointed me to . This question was deleted and is now only visible to users with 10k+ reputation.  What is the reasoning for deleting it instead of putting a historical lock on it?  The answers are pretty valuable to anybody using the Delphi IDE, but are not available unless your reputation is so high you may not even need the answers.  Similar questions exist that have not yet been deleted. What is the risk of them being deleted instead of getting a historical lock? I would hate to see the content of those questions and answers lost to the greater part of this community.

Problem background  This question is addressed to you, ♦ moderators. There is e.g. , which is full of very useful information. It's been a community wiki with more than 17k views with 51 answers.  The question is off-topic, there's nothing to discuss, but why it was deleted ? Couldn't you just lock it as you did with a several posts around ? The biggest problem is that our community can't even undelete it because it's protected by the ♦ law.  So now it's a community wiki question, which can't be seen nor even undeleted by the community.  Question  Could you undelete that question and let the community decide what to do with it? And if that is possible, could you lock that question to keep its content visible and as it is?    P.S. those reopen votes are there because of curiosity. We shall keep that question closed.


In Landau-Lifshitz - Vol 1. Mechanics, right after the introduction of the principle of leas action, there is the following comment:  It should be mentioned that this formulation ($S = \int\limits_{t_1}^{t^2} L(q, \dot{q}, t) dt$) of the least action is not always valid for the entire path of the system, but only for any sufficiently short segment of the path. The integral for the entire path must have an extremum, but not necessarily a minimum. This fact, however, is of no importance as regards the derivation of the equations of motion, since only the extremum condition is used.    Why is the least action principle not always valid for the entire path? Derivation of the equations of motion requires an extremum, not necessarily a minimum? How do we mathematically check if an extremum is in fact a minimum in this case? What are some physical examples that might give me further insight into this statement?

Edit: The previous title didn't really ask the same thing as the question (sorry about that), so I've changed it. To clarify, I understand that the action isn't always a minimum. My questions are in the points 1. and 2. below.  I understand that "principle of least action" is somewhat of a misnomer, since we find that to determine the path taken by a system, we need only impose the condition that the action be stationary, i.e., that $\delta S$ should vanish to first order for small variations of the path, and this leads to the Euler-Lagrange equations. In The Classical Theory of Fields, Landau & Lifshitz discuss the relativistic action for a free particle:  So for a free particle the action must have the form $$S = -\alpha \int_a^b ds$$ (...) It is easy to see that $\alpha$ must be a positive quantity for all particles. In fact, as we saw [earlier], $\int_a^b ds$ has its maximum value along a straight world line; by integrating along a curved world line we can make the integral arbitrarily small. Thus the integral $\int_a^b ds$ with the positive sign cannot have a minimum; with the opposite sign it clearly has a minimum, along the straight world line.  There is also a footnote, addressed a couple of paragraphs earlier, but which is relevant:  Strictly speaking, the principle of least action asserts that the integral $S$ must be a minimum only for infinitesimal lengths of the path of integration. For paths of arbitrary length we can say only that $S$ must be an extremum, not necessarily a minimum.  I have two questions regarding this:  How is the condition "the action must be a minimum for infinitesimal displacements" formulated? I've never heard of that outside of Landau & Lifshitz's books, and in Mechanics they mention it as well but doesn't go into detail. Is this discussed a bit more somewhere?  If for the whole path the action only needs to be stationary, how can we make the argument for the negative sign? If the action had to be a minimum then it would make sense, but surely the fact that $\delta S$ = 0 isn't affected by an overall sign?


I read (the beginning) of a short story about a man who invented nanobots.  He went into a radioactive room (nuclear reactor) where he trapped himself and started reading a book.  It may have been a short story written by Isaac Asimov, but I am not sure.  As far as I can remember, it was in a collection of short stories.  I also remember that during that time, I read Asimov's Science Fiction.  It was supposed to be continued on the next volume, but I did not find that volume.  I read that sometime between 1988 and 1992... but it was a bit older, when I read it.

I remember reading it while in middle school in English in the United States, so the latest it would have come out was 1998. I don't remember if it was all one author, or even the same universe. These are the stories I remember:   A man finds a way to create a medicine that prevents radiation poisoning (or possibly makes someone fireproof... it's a little confused in my head) and learns that part of the problem is finding a market for it. I vividly remember the inventor telling someone to not "let the doorknob ream you" as it slams shut. A bout of graffiti artists leads to the city buying anti-graffiti paint that dissolves any other paint put on top of it. After learning the futility of trying to paint over it, the protagonist consults with a friend and learns that the anti-graffiti paint will eat away at the paint above it at a steady rate, and will even eat successive layers of the anti-graffiti paint. he uses this property to engineer an animation involving a harlequin thumbing this nose at the officials even as they try to wash it away. Some guys (I want to say a gang) go to a clinic for an illegal nanotech transformation. The viewpoint character gets turned into a woman while a friend gets turned into a dog. After roaming about in their new forms, they return to find the clinic being raided, meaning there's no one to turn them back. I think I remember something bad happening to the one transformed into a dog where the transformation continued, erasing his human thought patterns. There was also a scene where the viewpoint character submitted to being sexually assaulted by his former friends as if it was simply to be expected given his form.   I don't remember if the first or the second story was the actual first story of the collection... I want to say that those are the order that they showed up as in the book.


I am wondering if it is possible to run a command without keyboard.  Actually, I would like to run dmesg and save the output into a text file. I have written previously a bash script which does the job, and without keyboard I can log in to the Guest account, but I cannot run the script. Even if I make it executable, it doesn't run if I double-click on it.  So, is there a way to run a command or a script without using keyboard?

When I double-click on a script in Nautilus to run it, the script just opens in my text editor with no option to run it. Using Nautilus, how do I run executable text files and/or scripts?


I have an object with over a million vertices. When I select subdivision surface, my Mac starts the rainbow circle and sits still. How do I fix this issue?

Essentially, my problem is that i am trying to render a scene, however, blender crashes on me early during the render. I only have about 14 total objects in the scene. (It's not that complex) I tried to render a different blender file which was bigger than the one that i am having problems with, and the scene renders just fine. There is no difference in the render presets for both of these files. However, i still cannot render the other scene. It gets to preparing scene data, but then it crashes.  Thank you.


In Fallout Shelter, do the stats of the parents affect the baby's?  E.g. If both parents have a high strength stat, will the baby have one too?

In Fallout Shelter you're able to make babies when you assign a male and female dweller to a residential area. When the babies are born, what determines the SPECIAL stats? It seems to be somewhat influenced by their parents, but there seem to be other variables. I want to breed children with high SPECIAL scores.


I have an installation of Ubuntu 16.04 on a dual boot machine.  Today I went to log in and it wont accept my password.  I tried following this guide:   I ran:  Press Enter for maintenance (or press Control-D to continue): root@mikes-ubuntu:`# mount -o rw,remount / root@mikes-ubuntu:`# ls /home root@mikes-ubuntu:`#   then  root@mikes-ubuntu:`# ls /home root@mikes-ubuntu:`#   According to the tutorial the users should be listed and from there you can reset the password. However, no user is listed at all....  Then I added a new user. However I cant log into that user either...  Press Enter for maintenance (or press Control-D to continue): root@mikes-ubuntu:`# mount -o rw,remount / root@mikes-ubuntu:`# ls /home root@mikes-ubuntu:`# root@mikes-ubuntu:`# ls /home root@mikes-ubuntu:`# ls snap root@mikes-ubuntu:`# adduser mike2 Adding new user 'mike2' ...   Does anyone have any tips on how to salvage this machine?

My Ubuntu is stuck in a login loop when trying to enter my desktop. When I login, the screen gets black and soon after that the login screen comes back.   I've read that the problem might be caused by an error depending on the graphics, here's my graphics card: ATI Radeon 7670M


I am an Indian travelling from India to Cayman Islands via Dubai and US.  I have a valid Cayman islands work permit. I have a layover in Newyork / Miami for around 5 hrs maximum. Should I need a transit visa to transit US or if I have a dubai visa, is it enough to transit US and reach Cayman islands?  if so what is the best alternative option to reach cayman islands without taking a US visa?

In Europe usually you don't need to go through immigration to change planes (unless you are entering/exiting Schengen). Is it the case in the US as well? May I catch a connecting flight on one of the US airports if I don't have US visa?


Current Lenovo think pad laptop SSD is permanently damaged. I have a new SSD with nothing on it. I have no DVD drive on laptop.  I can put Windows 8.1 ISO on a USB drive and that's all I can do. So, can I simply insert the new SSD to laptop, insert the USB drive to laptop, turn the power on and succeed installing the OS this way?

I downloaded Windows 8 as an ISO image, and I'd like to install it on a computer that doesn't have an optical drive.   Is it possible to install Windows 8 from a USB drive? How would I do this?


I have run the following command accidentally  sudo chmod 777 -R /   What should I do to get back to previous state?

I accidently ran  sudo chmod 755 -R /   instead of  sudo chmod 755 -R ./   I stopped it after few seconds, but now there is some problems such as  sudo: must be setuid root   How can I revert permissions back?


Is the following sentence grammatically incorrect because the word "they" is plural when there is only one teacher? How can it be corrected?     Thomas may be afraid to speak to the teacher as he feels they hold   prejudice against him.   Alternatives I concidered are     Thomas may be afraid to speak to the teacher as he feels he hold   prejudice against him.   and     Thomas may be afraid to speak to the teacher as he feels the teacher hold   prejudice against him.   but these seem even more awkward.

Is this sentence grammatically correct?  Anyone who loves the English language should have a copy of this book in their bookcase.  or should it be:  Anyone who loves the English language should have a copy of this book in his or her bookcase.


Reference: Atiyah and Macdonald, Introduction to Commutative algebra, page 46  Let $A$ be a commutative ring with 1 and $M$ a $A$-module. Then we define $Supp(M)$ to be the set of prime ideals $\mathfrak p$ of $A$ such that $M_\mathfrak p \neq 0$.  It is known that if $M$ is finitely generated then $Supp(M)=V(Ann(M))$ where $Ann(M)=\{f\in A |~ f M=0 \}$ and $V(E)=\{\mathfrak p \in Spec(A)|~ \mathfrak p \supset E\}$ for a subset $E$ of $A$.  (1) What is the relationship between $Supp(M)$ and $ V(Ann(M))$ if we drop the finitely generated condition, and do we have good examples to illustrate this?  (2) Another question is about the "naturality" of the support. Given a ring homomorphism $f:A\to B$ and a finitely generated $A$-module $M$, then we have  $$ Supp(B\otimes_A M) = f^{*~-1}(Supp(M)) $$ where $f^*: Spec B \to Spec A$ is induced by $f$.   I can only prove $ Supp(B\otimes_A M) \supset f^{*~-1}(Supp(M)) $ by using (1) and observing that $f(Ann(M))\subset Ann(B\otimes_A M)$.

I have a question which should be pretty basic commutative algebra, but I can't find a reference and I'm stuck on proving a result myself, so here it goes:  Let $\varphi: S \to R$ be a morphism of commutative rings and let $M$ be a finitely generated $S$-module. Then, we can "extend the scalars of $M$" by considering $M \otimes_S R$, which is naturally an $R$-module. I would like to get a description of $\text{Supp}(M \otimes_S R)$ (as an $R$-module) involving $\text{Supp}(M)$ and $\varphi$.  Maybe this helps: by Eisenbud's Commutative algebra with a view toward algebraic geometry, Corollary 2.7, the problem can probably be solved by finding a description of $\text{Ann}(M \otimes_S R)$ and it is not difficult to see that $\varphi(\text{Ann}(M))R \subset \text{Ann}(M \otimes_S R)$, but I fail to prove the other inclusion.


If we will look at the  of their properties, we will find the same mass for all. That looks like a result of some calculation, rather then a result of measurement. Was that important particles really found?

Why do the four spin 3/2 $\Delta$ baryons have nearly identical masses and lifetimes despite their very different $u$ and $d$ quark compositions?


I experienced in a predictive model for a dataset I have from experiments on human subjects, that the error of the prediction in 10-fold cross validation is less than leave-one-subject-out (leave-one-person-out). I think leave-one-person out has advantage over the K-Fold CV since it takes intra-individual variability into account and thus has higher generalization power than K-Fold. However I am not sure if I am missing any advantage of K-Fold over leave-one-subject-out.

Computing power considerations aside, are there any reasons to believe that increasing the number of folds in cross-validation leads to better model selection/validation (i.e. that the higher the number of folds the better)?  Taking the argument to the extreme, does leave-one-out cross-validation  necessarily lead to better models than $K$-fold cross-validation?  Some background on this question: I am working on a problem with very few instances (e.g. 10 positives and 10 negatives), and am afraid that my models may not generalize well/would overfit with so little data.


I want to see all my files, folders, and shortcuts in a simple, alphabetical list, without regard to what kind of file it is or whether it's a file or folder. Is there any way to do this? I'm talking about...  Alpha (file) Beta (folder) C (file) D (shortcut) E (file) Etc.  Thanks to anyone with an answer.

Is there a way to sort folders and files by their name all mixed together in Windows 7?  It would be easier to understand if you .  I want my folders and files arranged like the BEFORE situation of the first screenshot.  If there is no way to do that with Windows Explorer, is there any file management programs that I should try?  I've already tried Total Commander.


Please check below   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND  2561 redis     20   0 2761160   2.3g   1028 S 200.0 30.0  58:33.49 sysupdate  2576 redis     30  10  577576  61120    540 S 194.7  0.8  54:20.02 networkservice  I have no idea where they came from. How can I manage them

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


how do I install 12.04 when I am using 13.8? Is there a way to go back to 12.04 or do I have to install it over the old OS?

I just installed a new version of Ubuntu and I want to roll it back to the previous version.  How can I do that? Is that even possible?


Can I use "would" if there are no conditionals?  Here's example     That would be Jo calling. I'll answer it.   I don't think there's an implicit conditional behind that sentence. So I thought that "would" is used just for prediction or possibility, without conditional implication. Is it correct?  If it's incorrect, what is the conditional behind that example sentence?  Sorry for my poor English.

I have been reading these two posts on would:  &   If you want a domestic SUV, then the best choice would be the Ford Escape Hybrid. If you want functional air filters, the best choice would have to be K&N Air Filter. If you really want to use WMA, the best choice would be 2-pass encoding. If you really need a fighter bay, the best choice by far would be a manta bay.  Very similar examples exist with present-tense forms of to be:  If you want real wood, the best choice is engineered flooring. If you want to stay in colonial Quito, the best choice is the Hotel Real Audiencia. If you want HD programming, Dish Network is the best choice.  The post and its comments say that with respect to perceived speaker (un)certainty, perhaps the preterite makes the speaker seem more rather than less certain, by emphasizing that the logic of the hypothetical situation is being carefully evaluated. But I don't fully understand what on earth the logic here is. The auther mentioned this usage of would is quite fashionable. If so, it will account for the majority of would usages. Is it true?


The title kind of explains itself.  Docky will just randomly crash.  It will ask If I would like to restart or keep closed, If I try and restart, it wont.  Its becoming frustrating as I prefer Docky over Launcher.  Anyone have a fix for this?  BTW I'm a Ubuntu noob.... Thanks in advance for your help.

All operating systems freeze sometimes, and Ubuntu is no exception. What should I do to regain control when...   just one program stops responding? nothing at all responds to mouse clicks or key presses? the mouse stops moving entirely? I have an    In what order should I try various solutions before deciding to pull the power plug?  What should I do when starting up Ubuntu fails?  Is there a diagnostic procedure I can follow?


I can't find the way to align equations this way  And I can't align the list the way below  For the list I tried this   \begin{flalign*}     %\begin{equation*}     %\begin{aligned}     &x \tab &- \text{координата вдоль провода,}\\     &i \tab &- \text{время,}\\     &i(x, t) &- \text{распределение тока вдоль провода,}\\     &v(x, t) &- \text{распределение потенциала вдоль провода,}\\     &C \tab &- \text{ёмкость провода на единицу длины,}\\     &G \tab &- \text{утечка на единицу длины,}\\     &R \tab &- \text{сопротивление на единицу длины,}\\     &L \tab &- \text{индуктивность провода на единицу длины}.     %\end{aligned}     %\end{equation*}     \end{flalign*}   but get this Can anyone help me with pointing to some references or help to resolve it?

I have a equation that needs to be left aligned within the cases environment. Here's my code so far, which does not work:  \documentclass{article}  \usepackage{amsmath}  \newcommand{\diff}{\mathop{}\!d} \begin{document}  \begin{equation}\label{eq:algin}  \begin{aligned} \begin{cases} u_i^{k+1}(x)=\arg \min_{u} \Bigg\{ {}& \lambda\sum_{i=1}^{N}\int_{\Omega} r_i(x)u_i(x)\diff x  + \frac{\gamma}{2} \sum_{i=1}^{N}\int_{\Omega} \left( u_i(x)-m(x) \right)^2\diff x  + \frac{\mu}{2}\int_{\Omega} \left( u_i(x)-m(x) \right)^2\diff x \Bigg\}, \\ f'(x_{0})=0 \text{ : } z=f(x_{0}) \text{ is de horizontale raaklijn.} \\ \lim_{x\to x_{0}} f'(x)=\pm\infty \text{ : } x=x_{0} \text{ is de verticale raaklijn.} \\ g(x_{0}){R}_{0} \text{ : } z-f(x_{0})=f'(x_{0})\cdot(x-x_{0})   \text{ is de raaklijn.} \end{cases} \end{aligned} \end{equation}  \end{document}    My wrong output is:   I'm trying to get output like this:    This is my expected result    Thanks egreg. I found that when equation is so long (we cut it before), the equation number will automatically locate in bottom. Could we can relocate it in middle?  Code  \documentclass{article}  \usepackage{amsmath,mathtools}  \newcommand{\diff}{\mathop{}\!d} \DeclareMathOperator*{\argmin}{arg\,min}  \begin{document}  \begin{equation} \begin{dcases} u_i^{k+1}(x) \!\begin{multlined}[t] =\frac{-\lambda r_i(x)+\gamma \bigl( r_i(x)+b_i(x)\bigr)+\gamma \bigl( \alpha-\beta\bigr)}{\theta}\\  -\frac{\sigma \bigl( -\lambda\int_{i=1}^N r_i(x) \diff x + \sigma\sum_{i=1}^N \bigl( r_i(x)-b_i(x)\bigr) +\gamma N \bigl( 1-r_i(x)\bigr)\bigr)}{\gamma\bigl( \sigma N -1\bigr)}, \end{multlined} \\[1ex] f'(x_{0})=0 : z=f(x_{0}) \text{ is de horizontale raaklijn.} \\[1ex] \lim_{x\to x_{0}} f'(x)=\pm\infty : x=x_{0} \text{ is de verticale raaklijn.} \\[1ex] g(x_{0}){R}_{0} : z-f(x_{0})=f'(x_{0})\cdot(x-x_{0})   \text{ is de raaklijn.} \end{dcases} \end{equation} This is text \end{document}


I just got a Stack Exchange account a week or so ago, and I have not posted any questions. I went to post my first question and I got a message saying, "You can only ask 50 questions in a 30-day period." I haven't posted a single question yet. Any ideas how I can get around this?

I have only asked 2 questions ever; when I now try to ask a question, it says that I have exceeeded the limit of 50 questions/30 days.  What's going on? How can I fix it?


Earth is an accelerating frame. However, all experiments done on earth behave as if Earth is an inertial frame. How is this possible? Is there an experiment which can be done on earth to show it really is accelerating?

In many practical applications, one can consider the Earth-Centered Inertial () reference frame approximately as an inertial reference system, though strictly speaking, it is non-inertial.   Is there any quotable reference, where this claim is supported by a detailed estimation how small the effects are that one neglects if one considers the Earth's frame as inertial?


The app crashes when you click the button. There is a NullPointerException error, how can I fix that?  XML file of the crash button   <Button     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="@string/clickaqui"     android:id="@+id/registro"     android:layout_below="@+id/textView"     android:layout_centerHorizontal="true"     android:onClick="onRegister"/>   AndroidManifest:  <application     android:allowBackup="true"     android:icon="@mipmap/ic_launcher"     android:label="@string/app_name"     android:supportsRtl="true"     android:theme="@style/AppTheme" >     <activity android:name=".CreateMessageActivity" >         <intent-filter>             <action android:name="android.intent.action.MAIN" />              <category android:name="android.intent.category.LAUNCHER" />         </intent-filter>     </activity>     <activity android:name=".RegisterActvity"         android:label="@string/app_name">     </activity> </application>     Code of the crash button:  Intent intent = new Intent(CreateMessageActivity.this,    RegisterActvity.class);         startActivity(intent);

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?


On the Wikipedia page it says that . Wikipedia also say . However if particles are actually "dimensionless" there would be no way to deduce angular momentum, since angular momentum requires non-uniform momentum of an entity, which has to mean the entity consists of more than one point in space. Can someone explain to me how these two concepts are compatible?

I often hear about subatomic particles having a property called "spin" but also that it doesn't actually relate to spinning about an axis like you would think. Which particles have spin? What does spin mean if not an actual spinning motion?


I have three arrays/lists:  list1 = range(1,10) list2 = range(1,10) list3 = range(1,10)   I want to create an list of tuples containing an assortment of each of the values in my three lists. Essentially I want an output such as:  combo = [(1,1,1), (1,1,2), (1,1,3) ... (1,4,2), (1,4,3) ... (4,5,4), (4,5,5) ... (10,10,9), (10,10,10)]   It seems like such as simple problem, but I don't know where to start.

How can I get the Cartesian product (every possible combination of values) from a group of lists?  Input:   somelists = [    [1, 2, 3],    ['a', 'b'],    [4, 5] ]   Desired output:  [(1, 'a', 4), (1, 'a', 5), (1, 'b', 4), (1, 'b', 5), (2, 'a', 4), (2, 'a', 5) ...]


I'm currently developing a 3D game engine in C# using OpenTK.  I have basic game objects, and each game object has transform (translation, rotation and scaling). A game object can have components (much like Unity).  One game object (The camera game object) has three components, A camera, free move and a free look component. The free move component allows the user to move the camera around the scene, whilst the free look camera is SUPPOSED to rotate the camera. However, I get this odd effect:    (Note that, the plane isn't changing position, it seems the camera is ... turning upside down?)  On top of that, once I rotate the camera, moving the camera (using the arrow keys) gets really weird, up can become down, left can become right. It's all very odd.  Anywho, here is the update method for my Free Look component:  protected override void OnUpdate(object sender, UpdateEventArgs e) {     Rectangle bounds = Game.GetCurrentGame().Window.Bounds;      Vector2 center = new Vector2(bounds.Left + (bounds.Width / 2), bounds.Top + (bounds.Height / 2));      Vector2 mousePosition = new Vector2(System.Windows.Forms.Cursor.Position.X,                                             System.Windows.Forms.Cursor.Position.Y);     Vector2 deltaPosition = center - mousePosition;      bool rotX = deltaPosition.X != 0;     bool rotY = deltaPosition.Y != 0;      if(rotY)         Transform.Rotate(new Vector3(0, 1, 0), MathHelper.DegreesToRadians(-deltaPosition.X * sensitivity));     if(rotX)         Transform.Rotate(new Vector3(1, 0, 0), MathHelper.DegreesToRadians(-deltaPosition.Y * sensitivity));      if (rotY || rotX)         System.Windows.Forms.Cursor.Position = new Point((int)center.X, (int)center.Y);      base.OnUpdate(sender, e); }   here is the Rotate method in my transform class:  public void Rotate(Vector3 axis, float angle) {     rotation = (Quaternion.FromAxisAngle(axis, angle) * rotation).Normalized(); }   I hope someone can help me get to the bottom of this, I've been so frustrated!  If there's any other code you need to see, just let me know.

I see questions come up quite often that have this underlying issue, but they're all caught up in the particulars of a given feature or tool. Here's an attempt to create a canonical answer we can refer users to when this comes up - with lots of animated examples! :)    Let's say we're making a first-person camera. The basic idea is it should yaw to look left & right, and pitch to look up & down. So we write a bit of code like this (using Unity as an example):  void Update() {     float speed = lookSpeed * Time.deltaTime;      // Yaw around the y axis using the player's horizontal input.             transform.Rotate(0f, Input.GetAxis("Horizontal") * speed, 0f);      // Pitch around the x axis using the player's vertical input.     transform.Rotate(-Input.GetAxis("Vertical") * speed,  0f, 0f); }   or maybe  // Construct a quaternion or a matrix representing incremental camera rotation. Quaternion rotation = Quaternion.Euler(                         -Input.GetAxis("Vertical") * speed,                          Input.GetAxis("Horizontal") * speed,                          0);  // Fold this change into the camera's current rotation. transform.rotation *= rotation;   And it mostly works, but over time the view starts to get crooked. The camera seems to be turning on its roll axis (z) even though we only told it to rotate on the x and y!    This can also happen if we're trying to manipulate an object in front of the camera - say it's a globe we want to turn to look around:    The same problem - after a while the North pole starts to wander away to the left or right. We're giving input on two axes but we're getting this confusing rotation on a third. And it happens whether we apply all our rotations around the object's local axes or the world's global axes.  In many engines you'll also see this in the inspector - rotate the object in the world, and suddenly numbers change on an axis we didn't even touch!    So, is this an engine bug? How do we tell the program we don't want it adding extra rotation?  Does it have something to do with Euler angles? Should I use Quaternions or Rotation Matrices or Basis Vectors instead?


The trash folder has obviously been deleted. How can I restore the trash so that I can delete files?

I am a user of Xubuntu and I have a problem with it. When I delete any files outside home they can't be deleted and instead of that, a message appears to me and says "Unable to find or create trash directory". I hope I find a solution for this problem, as I can't get rid of useless files. Thanks.


My (UK) MacBook Air keyboard doesn't have # marked. It has ± and §, which I have never used,  but it doesn't have #, which is an extremely common character in computer code. Instead, I have to use the unmarked OPT+3.  I'm using terminal to SSH into a remote server. And through this connection I am loading up the nano editor. In order to access certain nano keyboard shortcuts, I have to go into the terminal settings and allow "Use OPT". But then I can't type # characters.

I am using Terminal version 2.5, where I have two requirements:  I need to be able to type the Meta key. I need to be able to type the # character, too (Option+3 for the UK keyboard layout)  How can I satisfy both of these? By default, (2) is satisfied, but (1) is not. I can then turn on "Use Option as Meta key", which satisfies (1), but breaks requirement (2). How can I have both? (It shouldn't be so hard for me to just be able to type.) Edit: what I'm looking for, for example, might be a way to just "Use Option as Meta key" for the left/right Option key, or a way to override the "Use Option as Meta key" for the sole exception of the # character.


Ok so if primitive data types in java are passed into methods, they are treated as pass by value. And if object data types are passed into methods, they are treated as pass by reference right? So in this code:  //Class 1 public void passByValue(int x){     x = 0; }  public void passByReference(Integer y){     y= 40; }  //MainClass(contains main method)      int primitiveType = 50;     Integer wholeInteger = 100;     Class1 a = new Class1();      a.passByValue(primitiveType);     a.passByReference(wholeInteger);      System.out.println(primitiveType);     System.out.println(wholeInteger);   This should result in primitiveType being equal to 50(variable hasnt changed). I understand that, however the Integer object is also not changed... So how does this work? Thanks!

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


For example, my entire party is versed in Arcana and they attempted to recall lore on a spell.   Party member A made the skill check while being helped by B and failed with advantage. B tried while being helped by A and failed with advantage. C tried while being helped by D and failed with advantage. D tried while being helped by C and failed with advantage. E tried while being helped by A and succeeded because of advantage.   By working together in this way can a party of X size perform 2X skill checks on the same task?

Picking a lock typically requires a DC 15 Dexterity check (Basic rules, p. 49). Likewise for manacles (p. 50), which can alternately be escaped with a DC 20 Dexterity check or broken with a DC 20 Strength check. But what happens if you fail?  The general rules for ability checks state (p. 58):     If the total equals or exceeds the DC, the ability check is a success—the creature overcomes the challenge at hand. Otherwise, it’s a failure, which means the character or monster makes no progress toward the objective or makes progress combined with a setback determined by the DM.   As a DM, how can I handle this in practice? In our last session, the players wanted to get inside a locked building to rescue people trapped inside. Picking the lock seemed like an easy enough task for the rogue, but unluckily he failed the check, and I wasn’t prepared for the consequences. There wasn’t much time pressure and no obvious reason why he couldn’t try again, so I allowed another attempt, but it just didn’t feel right.  I’m sure that similar situations will come up again, so I’d like some advice on how to deal with checks so that they don’t just turn into a tedious exercise of rolling until you succeed. I presume that  was left out of the game for good reason, but I’m not sure what to do instead. I suspect that this was a good occasion to use “progress with a setback” but that’s a fairly new thing for D&D and I’m not sure how to go about it. I’m unsure when I should use setbacks versus lack of progress, and in the latter case I’m unsure when I should allow players to try again versus requiring a different approach.  For example, suppose that a manacled player tries to pick the lock and fails the DC 15 Dexterity check. Now, the player could try to pick it again, or he could try one of the other escape methods, or he could wait for somebody else to rescue him, or he could simply succeed with some setback like a minor injury. How do I choose how to proceed? Or do I let the players choose?


I have a function that depends on the internet and downloads files, however sometimes the download time is too long or the sending request processes is failing.I wanted to know how can I set some-thing like a timer for the function, and if it exceeds the time (lets say a minute) to rerun the function from the beginning.

There is a socket related function call in my code, that function is from another module thus out of my control, the problem is that it blocks for hours occasionally, which is totally unacceptable, How can I limit the function execution time from my code? I guess the solution must utilize another thread.


Is there any reference in Canon or Legends on how the hyperspace travel of the Death Star is performed?  Is it in anyway similar to the hyperspace travels performed by other starships in the Star Wars universe? Or is there another kind of ftl-drive I am not aware of?  I understand that a , but is this referenced anywhere else? As a more technical approach, how would a massive body like this would achieve integrity in a hyperspace jump? Would all of these supposed hyperdrive thrusters need to be synchronized before the jump in order for the entire Death Star jump?

In the Star Wars saga, one of the most iconic weapons of the Empire was the Death Star: a self sustained weapons platform the size of a moon, with the capacity to destroy a planet. in A New Hope, we see the first Death Star in close proximity to the planet Alderaan, holding the planet hostage as the Empire tries to deduce the location of the Rebel Alliance's headquarters. In Return of the Jedi, we see the second Death Star in "dry dock" over the forest moon of Endor as it is being constructed.  My question is: How did the Death Star move? I imagine a spherical space station the size of a moon would be utterly massive, requiring a massive amount of thrust to move it. If it was constructed in low orbit of an inhabited planet/moon, the gravitational field would be immense, consisting of the planet/moon's gravity, and the Death Star's own considerable gravity. Breaking that gravitational field would be a massive task, yet we see no thrusters or engines on either Death Star. Were they hidden, stored under the station's surface while not in use? Was the station towed by another vessel?


I'm running Ubuntu 18.04, it crashes about once a week. Sometimes while watching video sometime or just web-browsing. I check the system log and kernel log they don't have any strange output at the crash time, last output before crashing is something normal being outputed several times a day.   And I not able to use Ctrl+ALT+F3 to enter virtual terminal or REISUB reset , every time I had to restart my PC by powerbutton. How can I find where the problems are?

I have read  and tried to follow the selected answer's advice. I have also read  but the second question I believe is unrelated to my issue. (But I'm not sure.)  When Ubuntu (Or possibly just Unity) crashes everything stops working. I have to completely turn the machine on and off. I cannot do the SysReq soft-reboot because I have not been able to find a key-equivalent for my keyboard/laptop model.   I can provide logs upon request, but to be honest I don't know which ones would be of use, or how much of those logs would be of use.   My computer is a Dell Inspiron 11 3000 series. I believe  is my model, assumed after cross-checking system specs with the listing I linked. The PC is running the newest LTS release of Ubuntu 14.04 Trusty Tahr.   At first I believed this to be a problem that only occurred during video playback, but while the system doesn't crash near as often when not playing back video, it still will occasionally.   I'm a software engineer, so I HAVE to have a reliable computer. I've recently decided to open-source all of my company's non-client-specific code, and changed all of my servers to Debian, and also installed Ubuntu on my main workstation. The company now uses 100% open source software on all of its machines. However, I will be forced to return to Windows if I can't resolve this issue, and I would really be bummed about that.    What are the steps, in plain language for an Ubuntu novice, of diagnosing crashes on Ubuntu? Once discovered, what resources can I use to fix these issues? And finally, is there a chance that I will be forced to use proprietary software in order to correct these issues?    Thanks.


I was trying to install Linux dc++ in my Ubuntu 14.04 using terminal. But the following was shown in terminal:  Reading package lists... Done  Building dependency tree         Reading state information... Done  Package linuxdcpp is not available, but is referred to by another package.  This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'linuxdcpp' has no installation candidate   What should I do to install Linuxdc ++?

How do I get to the Universe Repository in supported versions of Ubuntu?