Proving that two systems of linear equations are equivalent if they have the same solutions

I've just begun to work learn Linear Algebra on my own through Hoffman and Kunze's book and the first problem set already has a question that I can't solve:  Prove that if two homogeneous systems of linear equations in two unknowns have the same solutions, then they are equivalent.  I can't seem to figure out how to prove this without resorting to case work where you account for the cases where one of the coefficients are zero and when both are.  Is there an elegant way to prove in general that when two systems of linear equations have the same solutions, they are equivalent? The converse is obvious enough though.  Definition of equivalence from the text :     Let us say that two systems of linear equations are equivalent if each equation in each system is a linear combination of the equations   in the other system.


Are "white" and "black" ever capitalized when referring to people?

What is the accepted custom regarding capitalization when it comes to "White" and "Black" when referring to race, whether they are being used as nouns or adjectives?


What is the point of listing 1000 authors for a single scientific paper?

I arrived at the printer room this afternoon to collect my printing and I happened to notice that someone was yet to collect a printout of  that has been all over the scientific news the last few days/weeks. Of course, I was curious, so I had a peek.  It struck me that there was only one author... until I saw the asterisk indicating a full list of authors could be found at the end of the article.  There I found three full pages of authors. I have no intention of counting the exact number, but a quick estimate by word count suggests there are over 1000 authors from 133 institutions.  You always need to give credit where credit is due, that is a given. But to put it in context, there are at most 7 words of article per author. In fact, I can think of a number of problems coming from so many authors (like who do you contact if you have a question - the list is alphabetical and there doesn't appear to be a designated contact person).  What is the value of listing so many authors and why should (or shouldn't) it happen?  Update: Thanks everyone for the thoughtful answers. As much as I want to choose an answer, I honestly cannot decide between the two most upvoted, so I'm going to abstain from choosing one.


Roman numerals become “too wide” in table of contents

Following minimal document:  \documentclass{report}  \begin{document} \renewcommand*\thechapter{\Roman{chapter}} \tableofcontents \setcounter{chapter}{6} % Problem starts at chapter 7 \chapter{Seven} \chapter{Eight} \section{Eight-one} \section{Eight-two} \end{document}   yields this output (cut to size for your convenience):    Clearly, the chapter (and section) headings hang into the chapter (section) numbers. For the previous chapter numbers, this isn’t a problem since all chapter titles are aligned to the same column and the numbers I–VI are sufficiently narrow.  (The same happens regardless of document type, I’m actually using scrreprt with the same result.)  How can I prevent this?


labeling a group of members as private/public in c#

in a c++ class declaration, you can label a group of members as private or public, e.g.  private:   int x;   double y;   seems like there's no way to do this in c#. am I wrong?


I am trying to capitalize the first letter in each word for my page title in Nuxt.js My current code capitalizes the first word, however I need it to also capitalize the rest.    head() {     return {       title: this.$route.params.models.charAt(0).toUpperCase() + this.$route.params.models.slice(1).split('-').join(' ') + ' | ' + this.title,       meta: [         { hid: 'description', name: 'description', content: '' }       ]     }   }   How would I approach this?


I've started reading about Random Forests and one of the attributes that appeals to me is that they are good at dealing with independent variables that interact with one another.  Does Random Forest also "automatically" transform variables into, for example, the square of the variable?  Is there a good reason to square or perform other transformations of a variable (of course dependent on the situation)? For example if I have y = x1 + x2 + x3 is there anything to be gained by running the model y = x1 + x1^2 + x2 + x2^2 + x3 + x3^2?


What is the equivalent command to pathmunge in CentOS?

I have some installation  but they use pathmunge which caused me an error in Ubuntu. What is the equivalent syntax to the following script to do the same in Ubuntu?  /etc/profile.d/openssl.sh pathmunge /usr/local/openssl/bin   I did add pathmunge command to Ubuntu using this answer:  run nano ~/.bashrc && source ~/.bashrc and paste this:  pathmunge () {         if ! echo $PATH | /bin/egrep -q "(^|:)$1($|:)" ; then            if [ "$2" = "after" ] ; then               PATH=$PATH:$1            else               PATH=$1:$PATH            fi         fi }   When I login, I get this error:


Unable to launch Firefox w/geckodriver (v0.14.0) on Selenium ( Java 3.1.0)

I am trying to run a test program to confirm my selenium installation. I have a 64 bit windows desktop and have downloaded the 64 bit version of Geckodriver from seleniumhq.org   Here is my source code :  import org.openqa.selenium.WebDriver; import org.openqa.selenium.firefox.FirefoxDriver;  public class Name {  public static void main(String[] args)  {      String Firefoxdriverpath = "C://Desktop//geckodriver-v0.14.0-win64//geckodriver.exe";         WebDriver driver;     System.setProperty("webdriver.gecko.driver", Firefoxdriverpath);     driver = new FirefoxDriver();     driver.get("http://www.google.com");     System.out.println(driver.getTitle());     driver.close();  } }   I am getting a runtime error :  Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/base/Function     at Name.main(Name.java:15) Caused by: java.lang.ClassNotFoundException: com.google.common.base.Function     at java.net.URLClassLoader.findClass(Unknown Source)     at java.lang.ClassLoader.loadClass(Unknown Source)     at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)     at java.lang.ClassLoader.loadClass(Unknown Source)     ... 1 more   Any pointers on what I may be missing is helpful?


I need my footer to remain at the bottom of the page in landscape form. Most entries say that \usepackage{pdflscape} should do that, but it doesn't seem to be working,   \documentclass[12pt]{article} \addtolength{\parskip}{\baselineskip} \usepackage[margin=1in,includefoot]{geometry} \usepackage[fleqn]{amsmath} \usepackage{mathtools} \usepackage{siunitx} \setlength{\parindent}{0.25in}    %Tables preamble \usepackage[none]{hyphenat} \usepackage{float} \usepackage[thinlines]{easytable} \usepackage{longtable} \usepackage{array, booktabs, makecell, multirow} \renewcommand\theadfont{\bfseries\small} \newcommand\mceight[1]{\multicolumn{8}{l}{#1}} \newcommand\mctwelve[1]{\multicolumn{12}{c}{#1}} \usepackage{arydshln} \setlength\dashlinedash{0.2pt} \setlength\dashlinegap{1.5pt} \setlength\arrayrulewidth{0.3pt} \usepackage{pdflscape} \usepackage{afterpage}  \widowpenalty500 \clubpenalty=9996 \exhyphenpenalty=50 %for line-breaking at an explicit hyphen \brokenpenalty=4991 \predisplaypenalty=10000 \postdisplaypenalty=1549 \displaywidowpenalty=1602 \floatingpenalty = 20000  \usepackage[labelfont=bf, textfont=bf]{caption}  % Header and footer \usepackage{fancyhdr} \pagestyle{fancy} \fancyhead{} \fancyfoot{} \fancyfoot[R]{ \thepage\ } \renewcommand{\headrulewidth}{0pt} \renewcommand{\footrulewidth}{1pt} \usepackage{booktabs} \usepackage{dcolumn}   \begin{document}  \afterpage{\clearpage}  \begin{landscape} \begin{longtable}[ht]{ l*{12}{S[table-format=2.3]}} \caption{Quantile regresion results (pooled sample) for 2010-11} \label{tab:quantile}                                                             \\ \toprule \thead[b]{Dependant Variable:\\ log(hourly wages)}     & \mctwelve{\thead{Percentiles}} \\     \cmidrule(lr){1-1}\cmidrule(lr){2-13}       \multirow{2}{*}{\thead{Independent\\ Variables}}     & \multicolumn{2}{c}{10th}         & \multicolumn{2}{c}{30th}             & \multicolumn{2}{c}{50th}                 & \multicolumn{2}{c}{70th}                     & \multicolumn{2}{c}{90th}                         & \multicolumn{2}{c}{OLS}                   \\ \cmidrule(lr){2-3}\cmidrule(lr){4-5}\cmidrule(lr){6-7} \cmidrule(lr){8-9}\cmidrule(lr){10-11}\cmidrule(lr){12-13}     & {coeff} & {t-stat} & {coeff} & {t-stat} & {coeff} & {t-stat}     & {coeff} & {t-stat} & {coeff} & {t-stat} & {coeff} & {t-stat}  \\ \hdashline                                                               \\ \endfirsthead  %%%% \caption[]{Quantile regression results (contd.)}    \endhead                                    \toprule \thead[b]{Dependant Variable:\\ log(hourly wages)}     & \mctwelve{\thead{Percentiles}} \\     \cmidrule(lr){1-1}\cmidrule(lr){2-13}       \multirow{2}{*}{\thead{Independent\\ Variables}}     & \multicolumn{2}{c}{10th}         & \multicolumn{2}{c}{30th}             & \multicolumn{2}{c}{50th}                 & \multicolumn{2}{c}{70th}                     & \multicolumn{2}{c}{90th}                         & \multicolumn{2}{c}{OLS}                   \\ \cmidrule(lr){2-3}\cmidrule(lr){4-5}\cmidrule(lr){6-7} \cmidrule(lr){8-9}\cmidrule(lr){10-11}\cmidrule(lr){12-13}     & {coeff} & {t-stat} & {coeff} & {t-stat} & {coeff} & {t-stat}     & {coeff} & {t-stat} & {coeff} & {t-stat} & {coeff} & {t-stat}  \\     \midrule                                                                \\ \endhead \midrule \multicolumn{12}{r}{\footnotesize\textit{Continued on the next page}} \endfoot \endlastfoot %%%%        \textbf{Constant}     & 1.107   & 9.96     & 1.606   & 20.07    & 1.859   & 26.76 & 2.095   & 29.12    & 2.642   & 28.94    & 1.740   & 27.51     \\ \hdashline \textbf{Gender}     & 0.542   & 23.7     & 0.503   & 30.1     & 0.480   & 33.24 & 0.418   & 27.28    & 0.309   & 15.99    & 0.443   & 33.33     \\ \hdashline  \bottomrule     \label{tab:quantilereg}  \end{longtable} \end{landscape} \end{document}


What is the healthiest way to drink alcohol excessively and chronically?

If someone who is otherwise healthy decided to drink fairly heavily and consistently over a long period of time, what is the healthiest way to do so?  Example: Stay extra hydrated by drinking more water, take a multivitamin, get more sleep, etc.  Obviously the best solution would be to cease drinking, but IF that person is stubborn and won't quit - what's the best way to go about it?


Where do the white lines come from in my composite?

I'm having this issue for years now, and I'm not sure if I am doing something wrong on my end, or if what I would like to achieve - or expect to see - is even possible. My question is about compositing artifacts when using Blenders mask layers. Let me explain:    In the Blend file provided, there are two objects: Dragon A and B. Each of them is on a separate layer, rendered on a separate render layer, and masked with the other one. So A is masked out by B, and B is masked out by A. Like this:  scene setup    RenderLayers A and B    When I render, I write out two MultiLayer EXRs with 16bit depth. That Stuff, I feed into the following comp:    and it gives me this:    You can clearly see the white lines around the areas where the dragons mask each other.  If I comp in a weird fashion like this:    I get this:    It's not perfect, but still a lot better than the first one. What I am doing is kind of cutting off the bright alpha values, making a 0.75 alpha value equal 1.  My question is: Why do I see the white background shine through after all? Is it something which is fundamentally unchangeable and we have to live with? Am I doing something wrong on my side? Do you have an alternative solution?  Edit  The solution Ray Mairlot came up with solves the issue by only masking one of the two, the other one would exist un-masked underneath, and thus provides a perfect overlay. However, I'd like to still mask one against the other for specific reasons: I'm sending images to a web application, which layers them dynamically (a configurator in essence). There can be 30 or more image layers, each of them needs to be downloaded by the website visitor. If I could mask one part against the other, the individual file size would be smaller. Not really a necessary reason, but that's why the idea came up. The other reason is, if I mask the layers, the individual layers render faster. This can save me some 30% of the render time per configurator (which renders on average for 12 hours).


wrong numbering for subcaption in scrbook

When using the scrbook document class in combination with the subcaption  package, the numbering of subfigures seems broken. Consider:  \documentclass{scrbook} \usepackage{xcolor} \usepackage{caption} \usepackage{subcaption} \captionsetup{%   format=hang,%   font=small,%   labelfont={sf,bf},%   aboveskip=0.2\normalbaselineskip,%   position=top } \pagestyle{empty}  \begin{document} \begin{figure}   \caption{Black}   \label{fig1}   \centering \rule{2cm}{2cm} \end{figure}  \begin{figure}   \caption{More figures}   \label{fig2}   \centering   \begin{subfigure}{.3\textwidth}     \centering     \caption{Blue}     \label{fig2a}     \color{red}\rule{2cm}{2cm}   \end{subfigure}   \begin{subfigure}{.3\textwidth}     \centering     \caption{Green}     \label{fig2b}     \color{green}\rule{2cm}{2cm}   \end{subfigure}   \begin{subfigure}{.3\textwidth}     \centering     \caption{Blue}     \label{fig2c}     \color{blue}\rule{2cm}{2cm}   \end{subfigure} \end{figure}  Figure \ref{fig1} shows a black box. Figure \ref{fig2} shows colored boxes, where Figure \ref{fig2a} shows a red box, Figure \ref{fig2b} shows a green box, and Figure \ref{fig2c} shows a blue box. \end{document}   This results in the following display:    Clearly, the figure numbering in the text references is off by one for the subfigures. Instead, if I change the document class to article, it looks fine:     Why does this happen, and how can I prevent it?


Terms of use for procedural generation/simulation?

does anybody know if you need to pay royalties if you were to use something like an object with blender's ocean modifier or smoke simulator in a paid game?


screen shuts down when connecting to dock

I have a Lenovo T480s that I connect to my dock at work every day. Today all of a sudden my monitors remain black after I'm prompted for the encryption key for my disk. Usually, the login prompt should turn up.   Booting my machine without the dock works fine. Any ideas to how I can fix this? Any help is appreciated.


Could anyone give me some recommendations for an undergraduate textbook in combinatorics?

So, I have this textbook in combinatorics as part of my course in discrete math. Now, I'm not sure if this is a thing with all combinatorics textbooks, but it feels more like an advanced exercise book with some refreshers than a textbook meant for someone not very familiar with the field. Like, something you'd use to prepare for an exam or just kill time if you're already good at the subject, rather than using it to study from the ground up. Basically, they explain something, provide a couple of easy exercises, and the difficulty then abruptly picks up and oftentimes they'll suddenly get the jump on you with solutions that have nothing to do with the material taught in the section. This is all nice and good, but it makes it impossible for me to actually get the hang of anything. I think part of the reason is that the book is about 200 pages long and 50 pages are dedicated to detailed solutions, which are nice, but not as good as just more exercises. I'm used to books that provide 50+ exercises at the end of each section, starting off easy and then gradually picking up in complexity until the questions are even harder than what you'd expect in an exam. Just to emphasize the importance of this - Calculus was a complete nightmare for me at first but the book I'm studying from gradually got me on good terms with the subject, and I eventually started to enjoy it so much that I kept on studying from it without realizing that I'm well into calculus 2 material, integrating left and right, and really looking forward to the calculus 3 stuff. Now, I tried to google some recommendation, but every book I came across had one of two problems: it's either the same as the book I'm using right now (not enough exercises, so the difficulty picks up abruptly), or it has no solutions whatsoever to any of the problems. I would greatly appreciate a good recommendation. I really do appreciate this field but I can't find any entry point that isn't a frustrating mess.


I am writing my thesis with by use of the classicthesis style by use of biblatex for my bibliography. biblatex offers a compatibility mode for natbib and all of the basic commands shall work according to the documentation of biblatex. However, the command \Citet{} which is important for capital letters of authors like "van Krevelen" or "de Nevers". In my case \Citet{} does the same like \citet{}     \documentclass[     twoside,openright,titlepage,numbers=noenddot,headinclude,     footinclude=true,cleardoublepage=empty,     headsepline,     dottedtoc,     BCOR=5mm,paper=a4,fontsize=11pt,      ngerman,american,     ]{scrreprt}       \PassOptionsToPackage{utf8}{inputenc}    \usepackage{inputenc}    \usepackage[american]{babel}     \PassOptionsToPackage{%     backend=biber,     isbn = false,     doi = false,     language=auto,     style=authoryear-comp,     sorting=nyt,     maxbibnames=1,     natbib=true     }{biblatex}     \usepackage{biblatex}      \addbibresource{example.bib}      \usepackage{classicthesis}       \begin{document}         When citing with "Citet" one obtains for example:          \Citet{Krevelen.1950}.     \end{document}   with example.bib:  @article{Krevelen.1950,     author = {{van Krevelen}, D.W. and Hoftijzer, P.J.},     year = {1950},     title = {Studies of Gas Bubble Formation},     volume = {46},     number = {1},     journal = {Chemical Engineering Progress} }


Does hypnotic pattern make enemies automatically fail any saves, such as dexterity?

An enemy hit by Hypnotic Pattern is charmed (0 speed and incapacitated).  Does this make any sort of non-damage saves such as dex saving throw fail automatically because enemy is charmed / 0 speed / incapacitated?


Show that $A$ is invertible where $\left\lVert I - A \right\rVert < 1$

Let $A \in \mathbb{R}^{n \times n}$ be a real $n \times n$ matrix such that $$\left\lVert I - A \right\rVert < 1$$ where $I$ is the identity matrix and $\left\lVert A \right\rVert = \sup_{x \in \mathbb{R}^n \\x \neq 0} \frac{\left\lVert Ax \right\rVert}{\left\lVert x \right\rVert}$. I need to show that $A$ is invertible.   I'm not sure how to proceed here. I was thinking that since $\left\lVert I - A \right\rVert < 1$, I could use the fact that $A$ is a Lipschitz continuous function with Lipschitz constant $\left\lVert A \right\rVert_{\text{Lip}} < 1$, i.e., $A$ is a contraction. Since $A$ is a contraction and $\mathbb{R}^{n \times n}$ is complete, then by the Banach Fixed Point Theorem, $A$ has a fixed point. But I'm not sure how this would show that $A$ is invertible or if this is the right track.


I am a PhD student in the field of education and I enjoy reading SE questions to stimulate my mind when I need a break. I find academia to be one of my most frequently visited sites.    When reading questions, answers, and comments to questions of teaching practices I often see content I consider problematic given what is “known” (a word I will use loosely here) from research in educational psychology.    How do professors and lecturers learn to teach?    I do not mean this flippantly as I often see high-quality contributions on SE as well.   I suspect teaching courses as doctoral students is a consistent practice across fields, but I am curious to know what accompanies this in fields outside of education.  What other resources are provided besides having professors and lecturers learn on the fly and make their own conceptions of what good teaching practices are?  I understand this may be largely field and institution dependent. I also am asking from a U.S. context, but I would be interested to know if the structure is noticeably different between countries.


I have a NVIDIA GTX 960 graphics card with 2 GB of memory.  The problem I encounter is in virtualbox I can only give up to 128 MB of video memory. I need much more, so how do I configure virtualbox to give a virtual machine 1.5 GB of video memory?


Combinatorial proof that $\sum \limits_{k=0}^n \binom{2k}{k} \binom{2n-2k}{n-k} (-1)^k = 2^n \binom{n}{n/2}$ when $n$ is even

In  I prove, using generating functions, a statement equivalent to  $$\sum_{k=0}^n \binom{2k}{k} \binom{2n-2k}{n-k} (-1)^k = 2^n \binom{n}{n/2}$$ when $n$ is even.  (Clearly the sum is $0$ when $n$ is odd.)  The nice expression on the right-hand side indicates that there should be a pretty combinatorial proof of this statement.  The proof should start by associating objects with even parity and objects with odd parity counted by the left-hand side.  The number of leftover (unassociated) objects should have even parity and should "obviously" be $2^n \binom{n}{n/2}$.  I'm having trouble finding such a proof, though.  So, my question is     Can someone produce a combinatorial proof that, for even $n$, $$\sum_{k=0}^n \binom{2k}{k} \binom{2n-2k}{n-k} (-1)^k = 2^n \binom{n}{n/2}?$$   Some thoughts so far:   Combinatorial proofs for $\sum_{k=0}^n \binom{2k}{k} \binom{2n-2k}{n-k}  = 4^n$ are given by  and by .  The proofs are basically equivalent.  In Phira's argument, both sides count the number of paths of length $2n$ starting from $(0,0)$ using steps of $(1,1)$ and $(1,-1)$.  By conditioning on the largest value of $2k$ for which a particular path returns to the horizontal axis at $(2k,0)$ and using the facts that there are $\binom{2k}{k}$ paths from $(0,0)$ to $(2k,0)$ and $\binom{2n-2k}{n-k}$ paths of length $2n-2k$ that start at the horizontal axis but never return to the axis we obtain the left-hand side.  With these interpretations of the central binomial coefficients $2^n \binom{n}{n/2}$ could count (1) paths that do not return to the horizontal axis by the path's halfway point of $(n,0)$, or (2) paths that touch the point $(n,0)$.  But I haven't been able to construct the association that makes these the leftover paths (nor do all of these paths have even parity anyway).  So perhaps there's some other interpretation of $2^n \binom{n}{n/2}$ as the number of leftover paths.    Update. Some more thoughts:  There's another way to view the identity $\sum_{k=0}^n \binom{2k}{k} \binom{2n-2k}{n-k}  = 4^n$.  Both sides count the number of lattice paths of length $n$ when north, south, east, and west steps are allowed.  The right side is obvious. The left side has a similar interpretation as before: $\binom{2k}{k}$ counts the number of NSEW lattice paths of length $k$ that end on the line $y=0$, and $\binom{2n-2k}{n-k}$ counts the number of NSEW lattice paths of length $n-k$ that never return to the line $y =0$.  So far, this isn't much different as before.  However, $2^n \binom{n}{n/2}$ has an intriguing interpretation: It counts the number of NSEW lattice paths that end on the diagonal $y = x$ (or, equivalently, $y = -x$).  So maybe there's an involution that leaves these as the leftover paths.  (Proofs of all of these claims can be found on , for those who are interested.)


Recently I wanted to get info of struct timespec a field of lstat structure, but I couldn't get any. I tried  $ man timespec $ man -k timespec  timespec: nothing appropriate.   After some time I went through man page of clock_gettime for unrelated query and there I got to know the structure of timespec. But this was accidentally. So timespec word was present in man page of clock_gettime but I was not able to search it.  So, I would like to know, how to search for a word in all manpages? or do a grep kind of search? Any hints?


What would happen to short positions if one entity owns All the share and isn't selling?

Edit:  while related and interesting, does not ask or answer the question I'm asking. What it asks is what happens with regards to things like votes and dividends while there are outstanding long positions. One of the answers also covers what happens when a short squeeze forces short positions to cover when very little (but non-zero) stock is available for perchance. Specific it doesn't cover the question of what would happens if shorts are some how force to cover their position when no stock is offered for sale.  Original question: Basically a short squeeze, but even more so.  Person Z buys 10% of the float. They offer to loan it to short positions (with some sort of obligation to return it by a fixed date). The shot positions sell it back into the market. Person Z buys another 10% of the float. Go back to step 2 Repeat until Z is long by >100% of the float.  At this point there can be plenty of liquidity as 90+% of the stock is in owned by people other than Z. But what happens if Z then switches to doing nothing at all? They just let all the loan terms expire, collecting the returned shares but refuse to sell anything. Eventually they own all the shares, but someone still owns them more and there are none to buy... at any price. Granted this is 100% hypothetical and almost surely wouldn't happen in real life, but if it did... ?  The closest situation that I could see actually happening would be a contract denominated in a currency that no longer exists (say it was in DEM before the Euro came along) with no provisions for anything else. But in that case both parties are motivated to resolve the situation. But in the hypothetical above, the long position doesn't care. At a guess, some court would step in and either declare the long potion to be illegal, force a sale of shares at some set price, force the long position to accept something else of value or just declare the short positions bankrupt and liquidate them.


I stumbled upon this page:  Based on the description, it is clear that X12 must be an entirely new window system built from scratch, rather than an extension of X11.  So, my question is whether there are any actual ongoing efforts related to X12 development within any community, software alliance, etc?   EDIT:  I have checked the following question before asking this one:  However, the questions itself, as well as the answers are actually about x11 updates, which is why I don't believe this is a duplicate.


Checking whether a GeoServer service is WMS or WMTS?

I'm using GeoServer 2.10.1 connected to a PostGIS database. I have created a new workspace and activated the WMTS checkbox in the workspace definition. The service URL always contains wms either when I activate WMS or WMTS option. Then, I guess that this is not a good way to check whether the service is WMS or WMTS...  The service URL is as follow:  http://my.server.fr/geoserver/myworkspace/wms?   A layer complete URL is a follow (copied from Layer Preview page):  http://my.server.fr/geoserver/myworkspace/wms?service=WMS&version=1.1.0&request=GetMap&layers=test&styles=&bbox=1466568.5,6127476.88999999,1528548.733,6176365.98899999&width=768&height=605&srs=EPSG:3947&format=application/openlayers   I can't see any other place than the worspace definition where to specify this option for a given service (neither within stores or layers definition).  I need to make sure that the service is WMTS and not WMS. I have checked layers display within QGIS but I'm not able to find this information out within QGIS GUI.  Is there a simple way to check this out?


Significance contradiction in linear regression: significant t-test for a coefficient vs non-significant overall F-statistic

I'm fitting a multiple linear regression model between 4 categorical variables (with 4 levels each) and a numerical output. My dataset has 43 observations.  Regression gives me the following $p$-values from the $t$-test for every slope coefficient: $.15, .67, .27, .02$. Thus, the coefficient for the 4th predictor is significant at $\alpha = .05$ confidence level.  On the other hand, the regression gives me a $p$-value from an overall $F$-test of the null hypothesis that all my slope coefficients are equal to zero. For my dataset, this $p$-value is $.11$.  My question: how should I interpret these results? Which $p$-value should I use and why? Is the coefficient for the 4th variable significantly different from $0$ at the $\alpha = .05$ confidence level?  I've seen a related question, , but there was an opposite situation: high $t$-test $p$-values and low $F$-test $p$-value. Honestly, I don't quite understand why we would need an $F$-test in addition to a $t$-test to see if linear regression coefficients are significantly different from zero.


Example of non-isomorphic structures which are elementarily equivalent

I just started learning model theory on my own, and I was wondering if there are any interesting examples of two structures of a language L which are not isomorphic, but are elementarily equivalent (this means that any L-sentence satisfied by one of them is satisfied by the second).  I am using the notaion of David Marker's book "Model theory: an introduction".


In The Force Awakens, she has a vision, and a voice says:     These are your first steps   Now a number of former Jedi have become 'luminous beings' (not this crude matter). I'm trying to work out which one it is. It seems to be one of Yoda, Obi-Wan, Qui-Gon or even Anakin.   My question is: In Rey's vision, whose voice says "These are your first steps"?


I made a bit of a mistake, being a lazy bachelor and inexperienced at cooking.  I was making chili and when it came time to add beans I discovered I didn't have any canned beans.  I did however have some dried beans.  I decided to save time and add these directly to the pot of chili and add some water.  However, after much simmering the beans maintain a certain unpalatable crispness.  I have also read that undercooked beans contain a chemical lectin which can cause stomach discomfort.  I have also read that beans should be soaked, the water discarded to remove the lectin, and then boiled to cook them.  Is there any way to salvage this?  Should I just continue cooking the chili for hours?  Will I have to throw out my potentially delicious chili?


Determine the ring homomorphism with domain $\mathbb{Q}?$

Determine all the ring homomorphism from $\mathbb{Z}$ to $\mathbb{Q}$  and  $\mathbb{Q}$ to $\mathbb{Z}$ My attempt : Ring homomorphism from $\mathbb{Z}$ to $\mathbb{Q}$ Here $\mathbb{Z}$ is cyclic  and we know that any ring homomorphism send $1$ to $1$ So $f:\mathbb{Z} \to \mathbb{Q}$  send each integer  $n$ to the rational number $\frac{n}{1}$ This implies  identity is the only such homomorphism  from $\mathbb{Z}$ to $\mathbb{Q}$ But here im  confused  that how  to determine the ring homomorphism  from $\mathbb{Q}$ to $\mathbb{Z}?$


How can I change the settings of my table of contents, so that the sections and subsections are not indented as shown in the second picture. I would also like to center the title of the Contents. I am using the article class.


If a quadrilateral has a pair of equal opposite sides, and a pair of equal opposite angles, then is it necessarily a parallelogram?

I’m sorry I couldn’t upload a photo, so I’ll try to explain it as best as I can.     The quadrilateral has a pair of opposite and equal sides, and has a pair of opposite equal angles (85 degrees in the question).   Can I say this is a parallelogram or not?    I tried drawing a shape with those conditions that is not a parallelogram and I failed. Thanks in advance, and again sorry for not having a photo and I hope I explained it well enough.


Why do we use their instead of his in this sentence?     another driver flashes their lights


I am using Ubuntu 12.10 32-bit.  The machine detected the network printer Canon MF4800, but it can not find a driver.  The screen prompts for a driver.  I selected Canon but I cannot find the the series of my printer.  I went to the Canon website and searched for a Linux driver but drivers are not not available for the Linux OS.


When do I use present perfect tense instead of the simple past?

I've finished my work.   I finished my work.     When do I use one or the other?


I have a script that deletes files 7 days or older and then logs them to a folder. It logs and deletes everything correctly but when I open up the log file for viewing, its very sloppy.  log=$HOME/Deleted/$(date)  find $HOME/OldLogFiles/ -type f -mtime +7 -delete -print > "$log"   The log file is difficult to read  Example File Output: (when opened in notepad)  /home/u0146121/OldLogFiles/file1.txt/home/u0146121/OldLogFiles/file2.txt/home/u0146121/OldLogFiles/file3.txt   Is there anyway to log the file nicer and cleaner? Maybe with the Filename, date deleted, and how old it was?  Any suggestions help!


i'm looking for a simple code of function on java to round some decimals,   Example :  the input number will always be on this format #.## so the code should do this :  input 100.00 result 100.00 rounded by 0.00  input 100.01 result 100.00 rounded by -0.01  input 100.02 result 100.00 rounded by -0.02  input 100.03 result 100.05 rounded by +0.02  input 100.04 result 100.05 rounded by +0.01  i'm not sure if there is a java function that can provide this result.


Find a generator of the intersection of two cyclic subgroups, $\langle a^m\rangle\cap\langle a^n\rangle$

Let $a$ be an element in a group $G$. What is a generator for the subgroup $H = G_1 \cap G_2$ where $G_1, G_2$ are the groups generated by $a^m, a^n$, respectively?  Please can someone check my proof that I posted below?    I had actually already solved the question! I was just wondering if anybody could write out a fully rigorous proof so I can check if mine works. Basically, the problem is easy if the order of $a$ is infinite, but in the case where the order of $a$ is finite, a bit more care needs to be taken.  Anyway, here's how I did it:  We will prove that $⟨a^{lcm(m,n)}⟩ = H$.  Firstly, note that $a^{lcm(m,n)} \in G_1, G_2$ so $⟨a^{lcm(m,n)}⟩ \subseteq H$.  Now assume $a^k \in H$. If $a$ has infinite order, $m|k$ and $n|k$, implying that $lcm(m,n)|k$, so $a^k \in ⟨a^{lcm(m,n)}⟩$. If $a$ has finite order, say $r$, then there exists an integer $x$ such that $r|k-mx$ as $a^k \in G_1$. Thus $gcd(m,r) | k$. Similarly $gcd(n,r) | k$. So $lcm(gcd(m,r), gcd(n,r))|k$. It is not hard to show that this big lcm expression equals $gcd(lcm(m,n), r)$, so $gcd(lcm(m,n), r) | k$. Now let $lcm(m,n)=dp, r=dq$ for coprime $p,q$. Then $d|k$ so write $k=de$ for an integer $e$.   We would like to find an integer $s$ such that $r|k-slcm(m,n)$, but this is equivalent to $dq|de-sdp$ iff $q|e-sp$, and such $s$ can be found as $p,q$ are coprime!  Hence $a^k \in ⟨a^{lcm(m,n)}⟩$ and we are done.  Please let me know whether or not this proof is correct, and have I complicated things?


immediate fact $p/q \cdot b^n$ is a integer

in this question, under the answer of Calvin Lin,  I am not quite sure how is it an immediate fact that $p/q \cdot b^n$ is an integer. I tried couple of examples and they do work, but is there anyway to prove this?


I tried looking for ways to solve this equation and came across something like Lambert's W function, which, by the way, I did not understand a bit, because I've never learned it nor do I have a decent mathematical background. I also came across one more method called the Newton's method, but never used it either. Can the procedure to solve this equation be made a little bit clearer? I just plugged in the value on my calculator and it solved it for me, I guess it must have used some trial and error. Please advise.


If $x\sqrt{1+y}+y\sqrt{1+x}=0$ find $y'$

Find $\frac{dy}{dx}$ if $x\sqrt{1+y}+y\sqrt{1+x}=0$ for $-1\leq x\leq 1$   My Attempt $$ x\sqrt{1+y}=-y\sqrt{1+x}\implies x^2(1+y)=y^2(1+x)\implies x^2+x^2y=y^2+xy^2\\ 2x+2xy+x^2\frac{dy}{dx}=2y\frac{dy}{dx}+y^2+2xy\frac{dy}{dx}\\ \frac{dy}{dx}\Big[ x^2-2y-2xy \Big]=y^2-2x-2xy\\ \frac{dy}{dx}=\frac{y^2-2x-2xy}{x^2-2y-2xy} $$ How do I proceed further and find the derivative ?


Which of Tolkiens works describes the populations around and past the Sea of Rhun?

Are there any parts of Tolkiens books that outline in more detail the populations and life East of Rhun? I have seen differences in locations of cities and towns around the Sea of Rhun itself, as well as an Island in the centre that sometimes is omitted in other maps.. I'm wanting to know what is the best and most detailed description of this part of middle earth.


Probably that an $80\%$-truthful person actually rolled a $6$

A person, $A$, speaks the truth $4$ out of $5$ times. The person throws a die and reports that he obtained a $6$. What is the probability that he actually rolled a $6$?  I know there is a similar question like this  but my doubts are different from it and also I want to identify and solve total probability theorem questions so I posted a side doubt also. In my attempt, I defined the events  \begin{align*}  E_1&: \text{The person tells the truth.} \\  E_2&: \text{The person lies.} \\  E_3&: \text{The person reports that the die landed on a 6.}  \end{align*}  I noted that $P(E_1)=\frac{4}{5}$, $P(E_2)=\frac{1}{5}$, $P(E_3|E_1)=6^{-1}$ and $P(E_3|E_2)=0$ and obtained  \begin{align*}  P(E_3) = \frac{4}{5} \cdot \frac{1}{6} + \frac{1}{5} \cdot 0 = \frac{2}{15}. \end{align*} However, the correct answer is, $\frac{4}{9}$. What did I do wrong?  Side doubt: Even though the first experiment (truth and lying) is different from the second experiment, can we still apply total probability theorem? In my book the dependent experiment lies inside the sample space associated with the mutually and exhaustive events.


Blender not rendering specified dimensions

I was making a channel art photo for my YouTube channel, and everything went smoothly. But when I rendered the image it wasn't the resolution that I specified. I wanted the image to look like this:   But the rendering came out like this:  How do I make it so it doesn't do this??


How can I get the average width of a region or inside a curve? or  How can I calculate minimum,maximum, and average width of an irregular polygon? I have attached a figure, I want to know  how can I calculate width of yellow areas which are inside the polygons that exist in the main shape file.


How to prevent computer from going to sleep

On Win7SP1 I have a long job to run and want to save monitor power. I turn off the monitor. A few moments later the Win7 PC goes to sleep (cutting the job). I don't want that.  I want the Win7 PC to continue working on the job with the monitor off. What's the relevant control?


How to replace special regex chars in Python?

I need to match the following pattern:  text1.cps.text2 text1.text2.cps.text3 cps.text1   where text1, text2 are some random words. cps is one of several possible words. So I wrote the following regexp:  pattern = "(\w+\.)*?({0})(\w+\.)*"   And than I iterate over list of possible words:  for word in ['cps.','cps.tbl.']:    p = pattern.format(word)   So the problem is that item from the possible words can contain special regex chars. So I am looking for function that replaces each special character into something like that:  cps\. and cps\.tbl\.


I am not able to install ubuntu on macOs

When I boot the pendrive and choose the first option, the screen goes black, but on already I left it for hours and nothing appears!  P.S.: I already left separate space for the system and storage of ubunto in fat 32.  Version of MacOs: 10.15.4  someone help me please.  Thank you very much in advance.


App crashes while trying to get my Camera IDs

So I'm relatively new to Android and trying to build a Camera App. But I'm allready stuck with catching the Camera IDs.  I have my public CameraManager, a public String array and a public TextView and I was just trying to get the CameraIDs from my CameraManager and display the first of my IDs in my textview. And the App builds without errors but as soon as I try to execute it on my phone, it just crashes. Where is my mistake?  public CameraManager mCamera; public String[] cameraIDs; public TextView text = (TextView)findViewById(R.id.text);   And in my onCreate function:  try {     cameraIDs = mCamera.getCameraIdlist();     text.setText(cameraIDs[0]); } catch (CameraAccessExeption e) {     text.setText("Sorry, couldn't find camera device."); }   And, as requested, the error log from my phone:  java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.test/com.example.test.ThrowActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2360) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2509) at android.app.ActivityThread.access$1000(ActivityThread.java:153) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:5527) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:117) at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:149) at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:29) at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:54) at android.support.v7.app.AppCompatDelegateImplV23.<init>(AppCompatDelegateImplV23.java:31) at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:200) at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183) at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519) at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190) at com.example.test.ThrowActivity.<init>(ThrowActivity.java:26) at java.lang.Class.newInstance(Native Method) at android.app.Instrumentation.newActivity(Instrumentation.java:1068) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2350) ... 9 more   line ThrowActivity.java:26  public TextView text = (TextView)findViewById(R.id.text);


Sorting ls output where files end in numbers

Here is the output of my normal ls command:  f1  f10  f11  f12  f13  f14  f15  f16  f17  f18  f19  f2  f20  f3  f4  f5  f6  f7  f8  f9   So I have 20 files. I need them displayed as :  f1  f2 f3  f4  f5  f6  f7  f8  f9 f10  f11  f12  f13  f14  f15  f16  f17  f18  f19  f20     Is there any single-line command to this other than writing a script? I am sure some of you must have faced this weird situation. Note: the above is just a sample. In the actual scenario I need a list of all the file names in proper sorted order. (ranging from f{0..10000})


round() behavior when used with float and without

I am very new to Python. I am learning basic stuff and stumbled at this.  Why is 5 in the decimal not rounding to the next higher decimal digit in this example below?  >>> round(2.67576,4) 2.6758 >>> round(2.67575,4) 2.6757   I was expecting that the answer to both the expressions would be the same, but they aren't


What is the difference between a job and a process?

What is the difference between a "job" and a "process"?


If I turn off my PC while downloading a game will the download restart?

I'm downloading Fortnite and was wondering if I can turn off my PC while it's downloading. What would happen if I turned off my PC?


I want to attach some files to a post on one of Stack Exchange sites. What is the best way to do this?


Is there commercial-grade computer animation software available for Ubuntu, similar to the professional software sold for the Windows operating system?  This question goes out to those of you who may be using such software professionally.  My daughter recently graduated from the Art Institute of Seattle, and needs to put together an animation portfolio in order to interest employers in the field.  As you know, such software is usually provided by the employer and the costs are high - several thousand dollars.  I suggested that she investigate Ubuntu as a possible way to acquire the tools she needs.  But, since I have no idea what might be available, either as open source or proprietary animation software, I am reaching out to the Ubuntu community for help in the hope someone who is using such software can help her.  Thank you for reading this post, and for any information you might have.


Why does time reversibility imply equilibrium in a thermodynamic system?

I'm reading through Kardar's Statistical Mechanics of Particles; in the section 1.5 he says:     A reversible process is one that can be run backward in time by simply reversing its inputs and outputs. It is the thermodynamic equivalent of frictionless motion in mechanics. Since time reversibility implies equilibrium, a reversible transformation must be quasi-static, but the reverse is not necessarily true.   Why time reversibility implies equilibrium ?


Why my mesh isn't moving with my armature?

so, I am creating a cel-shaded RPG, and I created this low poly character for now so I can get the base animations and stuff done in unity. I rigged the character following a tutorial by Royal skies LLC on youtube, and the armature does not move with the mesh. can someone please tell me how to fix this? also it is worth mentioning that I am new to blender but pretty comfortable with unity.


In the derivation of the LSZ reduction formula equation (5.21) Srednicki claims that in case of an interaction term in the Lagrangian density $a^{\dagger}(\textbf{k})$ will no longer be time dependent. Now does that mean that the only modification to the formula of $\varphi(x)$ will be a time dependence of $a$'s and $a^{\dagger}$'s? So is that like an ansatz we use for $\varphi(x)$? Now even if we do assume this form of $\varphi(x)$, in line two of the derivation he makes the substitution $$a^{\dagger}(\textbf{k},t)= -i \int\:d^3x \:[e^{ikx} \partial_0\varphi(x) - e^{ikx} ik_0 \varphi(x)]\tag{5.2}.$$ Now in the derivation of this formula if we remember we explicitly had to use the time independence of the $a$'s. So what am I missing in this derivation that justifies the substitution in the case the $a$'s are time dependent?


I was suspended 1 day after already being contacted by a moderator, is this a moderator error?

June 13:  I answered several questions related to "how to make a carousel view (UI element) for Android OS" by giving them a few hints and a link to my blog:  or the open source project location on google code:  , instead of including the 37KB source code on SO, which in my opinion is not practical.  June 14: ChrisF issued a warning :     Hello,      I'm writing in reference to your Stack Overflow account:            We noticed that a substantial proportion of your posts seem to exist   only to promote your product or website. Per the FAQ:  Be careful, because the community frowns on overt self-promotion and tends to vote it down and flag it as spam. Post good, relevant       answers, and if some (but not all) happen to be about your product or   website, so be it. However, you must disclose your affiliation in your   answers. Also, if a huge percentage of your posts include a mention of   your product or website, you're probably here for the wrong reasons.   Our advertising rates are quite reasonable; contact our ad sales team   for details.      Any type of "astroturfing" promotion is not acceptable. It brings down   the overall value of genuine recommendations for everyone on the site.      If you can stay within the above guidelines, and offer questions and   answers of genuine benefit to the community which happen to mention   your affiliation or product in context -- and with full disclosure --   then your future contributions are welcome.      Regards, ChrisF Stack Overflow moderator   I replied asking if I should have posted the full 37KB source code , the relevant images, and the entire explanations instead of simply giving the short hints + link to code. No reply!  June 15: Out of the blue, without posting anything else from ChrisF's warning, I get another message, this time from Andrew Barber, who decided to take ChrisF's action further, and lock my account, saying:     Hello,      I'm writing in reference to your Stack Overflow account:            We noticed that a substantial proportion of your posts seem to exist   only to promote your product or website. Since you have been warned   about this multiple times in the past - including just a couple days   ago - and continue to make these posts, I am suspending your account   temporarily for 30 days.      When you return, if you can stay within our guidelines, and offer   questions and answers of genuine benefit to the community which happen   to mention your affiliation or product in context -- and with full   disclosure -- then your future contributions are welcome.      Regards, Andrew Barber Stack Overflow moderator   I feel uncomfortable with Andrew's attitude, of suspending my account after I already got a warning from ChrisF. I feel bad about not getting an answer to my reply after the warning, especially when the effort I put into creating the carousel tutorial was for helping others.  If they are not happy about putting links, ok , be it so, but at least they should have answered saying "stop putting links. we don't like that. instead flood SO with hundreds of line of code, and waste additional hours of your precious time into duplicating your original tutorial, because that is what we like".  C'mon guys, this really seems to be the wrong attitude, and I  don't think I will feel like helping others around here again. A warning might be ok even regardless of motives and facts, but what Andrew did seems to be an error.


Security importance of Key Schedule in Block Cipher

For example block cipher AES-128, Key size is 128bit and it is used to make a 10 round key which is total 320bit.  Question 1. If i use another Key schedule algorithm in AES, then security decreased or remain same? In other words, if the key schedule algorithm of AES has some relationship with AES encryption itself, then it will be decreased, or it will be same if the new key schedule algorithm is safe enough.  Question 2. Why we expand key? brute force will take O(2^128) time regardless of the key schedule is strong or not. what is the advantage of making key expend? I was curious about this when I was learned about 3DES. Which developed because the former DES has weak key length 56bit so vulnerable to brute force attack, i was wondering why doesn't they just remove key schedule process and use the whole round key as a key.


Multiple Groups Graph on Google Sheets. Please Help


Determine all primes $p$ for which $5$ is a quadratic residue modulo $p$

I need to determine all primes $p$ for which $5$ is a quadratic residue modulo p.    I think I'll need to use quadratic recprocity laws to do this, i.e., I need to need to find numbers $p$ where $x^2$ is congruent to $5 \bmod p$. I'm ok doing this for single values of $p$. But how do I find all primes for which this holds?   Thanks.


convex function in open interval almost everywhere differentiable

Let $I \subset \mathbb{R}$ be an open interval and $f: I\to \mathbb{R} $ is convex. (That is, whenever $a, b \in I$ and $0\leq t\leq 1$ then $$f((1-t)a + tb) \leq (1-t)f(a) +tf(b).$$ How can I prove that $f$ is differentiable almost everywhere? The proof of Alexandrov theorem or the contents in Rockafellar's "Convex analysis", Theorem 25.5 mentioned in  are too difficult for me, who is studying elementary real analysis. Are there any other proof of this? (I hope there is because it is the simplest case in which $ n =1$.)


W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://repository.spotify.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 13B00F1FD2C19886 W: Failed to fetch http://repository.spotify.com/dists/stable/InRelease   W: Some index files failed to download. They have been ignored, or old ones used instead.   How can I fix spotify?


Which is greater? $\sqrt{n}^{\sqrt{n+1}}$ or $\sqrt{n+1}^\sqrt{n}$  I know that $\sqrt{n}^{\sqrt{n+1}}$ is greater but I tried using induction and I couldn't figure it out. Thanks for the help.


How to make git mark a deleted and a new file as a file move?

I've moved a file manually and then I've modified it. According to Git, it is a new file and a removed file. Is there any way to force Git into treating it as a file move?


I installed VMworkstation on a fresh Windows 10 operating system. When I tried to create any machine I got the following error:     VMware Workstation and Hyper-V are not compatible. Remove the Hyper-V role from the system before running VMware Workstation.   I checked the "Windows Features" and I found that Hyper-V is disabled. Also I used the following CMD shell and power shell commands to disable Hyper-v.  CMD Shell  bcdedit /set hypervisorlaunchtype off   CMD Shell  dism.exe /Online /Disable-Feature:Microsoft-Hyper-V-All   PowerShell  Disable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All   Then I restart the machine, then I reinstall the Vmware workstation again and still it doesn't work.  Update: The operating System is windows 10


Are virtual particles limited by the speed of light?

I have recently been reading about Quantum Electrodynamics which I found very interesting, but even more confusing.  I understand photons mediate the electromagnetic force and interactions between charges can be described by virtual photon exchange. And that in Quantum Mechanics particles paths can be evaluated by sum over all paths...  An electron travelling from one point to another will take all paths, emitting and reabsorbing virtual photons. Does the electrons take all paths including those that involve faster than light velocities?  Is this question null, Does it mean anything to ask about properties of virtual particles?  Do I have the wrong idea about what virtual particles are?


I have to evaluate a function (3x-2) in a interval [-10,10] with precision increments from 1, 0.1, 0.01, 0.001, 0.0001, etc. I tried this  a=1.0 for x in range(1,40):     for y in range(-10,10,a):         c=3(x)-2         print(c)     a=a/10   (The first for is because I need to get 40 decimals) But I got this error   for x in range(-10,10,a): TypeError: 'float' object cannot be interpreted as an integer   Thanks for the help.


How can I save an altered image in MATLAB?

I want to read an image into MATLAB, draw a rectangle on it, and then save the image.  Also, I'm just learning MATLAB--please be gentle. It seems like it should be simple, but I can't seem to do it.  im = imread('image.tif'); imshow(im); rectangle('Position', [100, 100, 10, 10]); imwrite(im, 'image2.tif');   Even though I can see the rectangle on the image, the saved image does not display the rectangle. How can I save the image and have the rectangle show up?  FWIW, I've already tried saveas(), but that gives me a HUGE image. Is there a way to use saveas() and make the saved image the correct size?


I'm trying to double arrows their X Motion and it's working great except for the part that I can't apply the scoreboard data to the entities. My system is so build that it can handle multiple arrows at once but I get stuck in the last command  execute as @e[type=arrow] store result score @s Bullet.Y run data get entity @s Motion[1] 100000  execute as @e[type=arrow] run scoreboard players operation @s Bullet.X *= 2 F.Data  execute as @e[type=arrow] run data modify entity @s Motion[0] set from **score @s Bullet.X**   This is not a thing but it would be really handy to use. I just don't know how to do this with using a valid command.


How to gunzip files recursively (or how to UNDO 'gzip -r')

I am learning Linux and I was trying the gzip command. I tried it on a folder which has a hierarchy like  Personal/Folder1/file1.amr Personal/Folder2/file2.amr Personal/Folder3/file3.amr Personal/Folder4/file4.amr   I ran     "gzip -r Personal" and now its like  Personal/Folder1/file1.amr.gz Personal/Folder2/file2.amr.gz Personal/Folder3/file3.amr.gz Personal/Folder4/file4.amr.gz   How do I go back?


Is walking up/down the road/street applicable if the street is not sloped?  I think I heard something about "with/against the numbering of houses" but I'm not sure if it's correct.  Also, if that were correct, why is walking down the street  than walking up the street?


Cannot mount USB stick - errors out with "$MFTMirr does not match $MFT"

I have an NTFS-formatted USB stick.  When I connect it to a Windows system, it works fine.  However, I receive this error output when I try and mount the USB stick on my Linux machine:  Error mounting /dev/sdb1 at /media/: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000" "/dev/sdb1" "/media/sorin/LICENTA"' exited with non-zero exit status 13: $MFTMirr does not match $MFT (record 0). Failed to mount '/dev/sdb1': Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the /dev/mapper/ directory, (e.g. /dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation for more details.   What can I do to fix this issue and make my USB stick usable on Linux again?


Quadratic models with R. The use of poly(..) and I(..) functions (R-language)


, the author makes 4 French baguettes. That is probably 2 more baguettes than I can eat before they get stale.  Recipe (transcribed from the video):  Ingredients:   Bread flour, 700 g Instant dried yeast, 0.5 tsp Kosher salt, 1.5 tsp Cool tap water, 520 g   Steps:   Whisk 1st 3 ingredients together. Add water and mix with the handle of a wooden spoon. Cover the bowl with clear wrap and rest for 45 minutes at room temperature. Repeat 4 times:   Turn onto a flat surface, wet your hands, and fold from each side to center, then use a dough scraper to put the dough back into the bowl (2:30 in the video). Cover the bowl with clear wrap and rest for 45 minutes at room temperature.  Sprinkle the work surface with bench flour and turn out the dough. Divide the dough into 4 equal pieces (each about 310 g). Shape the baguettes (6:30). Leaving the baguettes on the work surface, cover them with lightly oiled clear wrap. Let them rest for 15 minutes. Prepare a well floured bakers couche (7:20). Form the baguettes (7:50), dust lightly, and transfer to the couche. Cover with a tea towel and let them rise for 20 minutes, then a further 12 minutes while the oven preheats to 200°C/400°F. Place a pan of boiling water in the bottom of the oven. Transfer each baguette to a lightly oiled baking sheet using a peel or cardboard covered in aluminum foil (10:45). Spray the baguettes lightly with water Score the baguettes with a razor blade or very sharp knife (11:20). Place the baking sheet(s) in the oven and spray a little water over them to moisten the crust. Bake for 8 minutes, then turn the baking sheet(s) 180° for more even baking, releasing the steam from the oven carefully. Transfer the baguettes to a cooling rack.   Note that I have not tried this recipe yet, but plan to very soon.  How late in the process can I freeze the dough? I assume that when I want to eat it later, I can just thaw the dough and continue the process from that point.


Do you have tricks or techniques to remember all the rules to the games you're playing? I would like to run my first game as a gamemaster, but I'm struggling with remembering all the feats and competency rules.


I am new to GIS software. I've played with Google earth a bit and am familiar with downloading Canadian topographic maps. Anyways, I've been playing around with qgis. I have imported a few georefferenced tiff files and a gpx file.   I am having difficulty displaying the raster maps correctly though. The maps looks squished in the vertical dimension. If I zoom in each pixel is not square, it is a short/fat rectangle. I feel like it has to do with the coordinate system?  Does anyone have any ideas what i might do/read up on in order to figure out how to make the pixels square and the maps not stretched?


Uniformly continuous function $f:[0, \infty)$ $\to$ $\mathbb R$

I've got some inquiries while doing exercise. I want to share it and ask advices.  Here's the problem.    We have uniformly continuous function $f:[0, \infty)$ $\to$ $\mathbb R$ satisfies $\lim\limits_{n\to\infty}$ $f(n+x)=0$ whenever $x \in [0, 1]$ and $n \in \mathbb N$. Show that $\lim\limits_{x\to\infty}$ $f(x)=0$. And if the uniformly continuous condition changes into continuous condition, the statement still holds?    In my trial, I approached with the $\epsilon$ - $\delta$ method and made some outcome but little bit unsatisfied. And I have difficulty in finding some easy counter-example of the if-question. I wonder there are any ideas better than $\epsilon$ -$\delta$ method and easy counter-examples.  EDIT:  Here's the specification about the curiosity I have.  In this problem, the difference between limit through natural number and through real number matters. I think because of $\mathbb N$ $\subsetneq$ $\mathbb R$, limit through $\mathbb R$ implies limit through $\mathbb N$ but the converse doesn't. What I had to request was the logical explanation about this difference and background understanding of this theme. This situation is very common in analysis but I haven't seriously thought about it.


Short story about a boy who lives in a time warp to age faster

A long while back I read a fairly short story about a boy who happened across a bunker that was stocked with supplies for longterm survival, MREs and such I believe.   The major plot device was that in the sink (I think) there was a gateway or portal to a black hole. He comes to this conclusion after holding a stopwatch outside of the doorway of the bunker and notices that it is spinning extremely slowly. He comes to the conclusion that he will stay in the bunker for a calculated amount of time such that he is an adult in the outside world when he leaves.  However, at a certain point he notices a creature getting ever-closer in the sink or portal. At the end of the story when he leaves the creature or machine completely destroys the portal and bunker with it. I'm not sure of the conclusions he makes on this, perhaps that the creature was built to destroy the warp in space-time by some other species on the other end of it.  Does this sound familiar to anyone? I've wondered about what the title of this story is for years lol  Thanks!


Compare Strings according to my method code in java

Im new to java. sorry if had made any mistakes in asking the question. How to compare 2 strings, This is my code. I appreciate everyone who tried to help me.  public static void displayLogin() {     System.out.println("\n****** Login Menu ******");     Scanner loginInput = new Scanner(System.in);     System.out.print("Enter Username: ");     String userName = loginInput.next();     System.out.print("Enter Password: ");     String password = loginInput.next();     if (userName == "admin" && password == "admin123") {         displayMainMenu();     } else {         System.out.println("\n#Incorrect Username or Password, Please Try Again#");         displayLogin();     }     loginInput.close(); }


Does deleting an iMessage on a device deletes it in all of the other iCloud synced devices?

If I have my iPad and my iPhone synced through iCloud and I can see that my text messages  are being received/sent on both. If I send an iMessage on my iPad and immediately delete the entire text thread on my iPad, does it in turn delete the text threat off of my iPhone?  If not, does it show the iMessage I sent from my iPad?  Pretty much what happened was I was over my buddy's house and his iPhone and iPad are synced to iCloud.  I am assuming this because he had been text messaging me all day and all of the most current text messages were showing on his iPad.  I used his iPad to send a text message to my wife with some of our bank account information she needed.   I immediately deleted the text thread from the ipad (My wife also has an iPhone so I am assuming it was an iMessage).   My question is does this iMessage go to his phone still if I deleted it?  Or does it delete from his phone because I deleted it from his iPad?


How can I create a 'little subtitle' for a section?

Here's my code:  \documentclass[]{article} \usepackage{titlesec}  \begin{document}  \titleformat{\section} {\normalfont\Large\bfseries}{\thesection}{1em}{}[{\titlerule[0.8pt]}]  \section*{29th March 2014} \textit{A little subtitle}  Here starts my first paragraph. \end{document}   Here's a screencap of the resulting document:   I'd like the 'little subtitle', being part of the section title, to be situated above the horizontal line.  I assume the easiest way to implement this is to create a section format with two inputs: a "Date" and a "Little subtitle". In this case, my code would then be:  \section*{29th March 2014}{A little subtitle}   How would I go about doing that?


How to upgrade the HTC One X (with AT&T) from ICS to Jelly Bean from Indian telecome?

I purchased HTC One X unlocked (with AT&T) with Android ICS. I am using this phone in India with Airtel SIM.  How can I upgrade the device to Jelly Bean?


Prove a.s. convergence of $(X_n)_n$ satisfying $E(X_{n+1} \mid F_n) \leq X_n+Y_n$ for $\sum_n Y_n<\infty$

I am have a problem with proving a convergence of a sequence of random variables in the given context:  Let $F_n$ be a filtration. Assume that $X_n$ and $Y_n$ are non-negative and integrable $F_n$-adapted random variables for $n\geq 0$. Furthermore, I assume that: $\mathbb{E}[X_{n+1} \mid F_n]\leq X_n+Y_n$ and that  $\sum_{n}Y_n < \infty$. Under the above conditions, I should show that $X_n$ converges almost surely for $n\rightarrow \infty$.  My approach has been to define a variable $Z_n=X_n-\sum_{i=0}^{n-1} Y_i$, and to set this into the expression for the conditional mean of $X_{n+1}$, but this did not gave any result. Anybody has an idea to this?


Eval on clone object changes values of parent object

This is a part of a large function, but to put it simply:  var round1 = {gg: "wp"}; var round2 = round1; eval('round2.gg="bp"')   This gives:     round2 == {gg: 'bp'}   But also changes:    round1 == {gg: 'bp'}   How to get around this ?  Edit: why I need eval ?  As a part of my function, i have the paths of the bigobject recorded as strings in an array, such that i can use eval to change the value of a specific property and copy it in a cloned object.   Example:  var bigobject = {   a: { x: "1", y: "2" },   //b: similar } var pathobject [".a.x",".a.y",".b.x",".b.y"]   // This eval is run in loop, so i = index of loop. but lets say i=0 var temp_object = bigobject; var i=0; eval('temp_object' + pathobject[i] + '=' + '5');


How can I easily find other players in Mincraft PE multiplayer?

We are playing multiplayer on a local wifi on Minecraft PE. Since it is an unlimited world size, when a new player joins the world we cannot find each other. Is there an easy way to find each other or teleport to where player is?


I was wondering, I have optifine and I can get HD yexture packs but if I get anything over 128x Minecraft crashes.  Why is this happening?  My computer is very new and has great proccesors and graphics cards.  My processor is an intel i7 3,4Ghz and my graphics card is a one of the higher AMD Rathelons and I usually get 200fps with Minecraft.  I also have 8GB of RAM.  EDIT: When I use mc-patcher with a 256x256 texture pack I get this error report:  ---- Minecraft Crash Report ---- // Would you like a cupcake?  Time: 6/23/13 7:46 AM Description: Rendering screen  java.lang.OutOfMemoryError: Java heap space     at bio.a(SourceFile:388)     at bio.<init>(SourceFile:136)     at bio.<init>(SourceFile:108)     at biq.a(SourceFile:127)     at biq.c(SourceFile:94)     at bir.b(SourceFile:80)     at bge.d(SourceFile:350)     at bge.c(SourceFile:301)     at bjx.a(SourceFile:146)     at axt.a(SourceFile:175)     at bjw.a(SourceFile:109)     at bfq.b(SourceFile:768)     at net.minecraft.client.Minecraft.K(SourceFile:597)     at net.minecraft.client.Minecraft.run(SourceFile:526)     at java.lang.Thread.run(Unknown Source)   A detailed walkthrough of the error, its code path and all known details is as follows: ---------------------------------------------------------------------------------------  -- Head -- Stacktrace:     at bio.a(SourceFile:388)     at bio.<init>(SourceFile:136)     at bio.<init>(SourceFile:108)     at biq.a(SourceFile:127)     at biq.c(SourceFile:94)     at bir.b(SourceFile:80)     at bge.d(SourceFile:350)     at bge.c(SourceFile:301)     at bjx.a(SourceFile:146)     at axt.a(SourceFile:175)     at bjw.a(SourceFile:109)  -- Screen render details -- Details:     Screen name: bjw     Mouse location: Scaled: (125, 143). Absolute: (375, 530)     Screen size: Scaled: (427, 321). Absolute: (1280, 961). Scale factor of 3 Stacktrace:     at bfq.b(SourceFile:768)     at net.minecraft.client.Minecraft.K(SourceFile:597)     at net.minecraft.client.Minecraft.run(SourceFile:526)     at java.lang.Thread.run(Unknown Source)      -- System Details --     Details:         Minecraft Version: 1.5.2         Operating System: Windows 8 (amd64) version 6.2         Java Version: 1.7.0_25, Oracle Corporation         Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation         Memory: 5540872 bytes (5 MB) / 904527872 bytes (862 MB) up to 954466304 bytes (910 MB)         JVM Flags: 2 total; -Xms512m -Xmx1024m         AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used         Suspicious classes: [com.prupe.mcpatcher.MCPatcherUtils, Config, MCLogger, ...], [com.prupe.mcpatcher.mod.ColorizeItem, AAHelper, TessellatorUtils, ...]         IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0         LWJGL: 2.4.2         OpenGL: AMD Radeon HD 7570 GL version 4.2.12002 Compatibility Profile Context 9.12.0.0, ATI Technologies Inc.         Is Modded: Very likely; Jar signature invalidated         Type: Client (map_client.txt)         Texture Pack: 1.5TP_HD_By_Lancer_256x256.zip         Profiler Position: N/A (disabled)         Vec3 Pool Size: ~~ERROR~~ NullPointerException: null


I know similar questions have been asked before, though any links to contact Google Scholar that were provided in older answers no longer work. I have two last names, example: First name Jane, Last name "Doe Smith". The google scholar algorithm chooses only the second part of my name as my "last name", even when the journal has published my work as Doe Smith, Jane. Instead Google Scholar will present it as JD Smith. Is there anything I can do? Any way to contact Google Scholar, or fix it myself? I'm assuming the answer is to just live with it. I thought about just publishing under Jane Doe or Jane Smith from now on, but I've already published a lot under my name, and realistically, if I were to pick one I'd want it to be Doe, which may confuse the system that always wants to pick Smith.


Let H be a proper subgroup of G and  a $\in$ G, a $\notin$ H. Suppose that for all b $\in$ G, either b $\in$ H, or Ha = Hb. Show that H is normal subgroup of G. How do I proceed on this?


xUbuntu Default desktop Icons do not display?

Even though I have the default icons set to display in Settings, they do not display. See the image below. Ideas????


I have a server at mysite.no-ip.org. Everything is working fine and I have a blog and owncloud that I access writing mysite.no-ip.org/blog and mysite.no-ip.org/owncloud. Now, I want to create subdomains so that I can write blog.mysite.no-ip.org and owncloud.mysite.no-ip.org.  I have looked a lot into it and the simplest tutorial was this one which I followed.   Except that I am not on my server but ssh into it remotely so if I use localhost I cannot see if this works I believe. This is my first obstacle, can I follow this tutorial without being present next to the server?  I also just discovered CNAME records which (I am not completely sure) seem necessary to what I want to do. I use no-ip.org and I have tried to follow something like this but this is not really clear either   Does anyone have any pointers? This is quite shady to me and I have no idea if I am far from the solution or really close (at least if I could try localhost that would be a first step in order to check my Apache conf but I can't even do it since I ssh).  Anyways, thanks for your help in advance. Any help, link is welcomed.


In The Force Awakens, we see that FN-2187's superior, Captain Phasma, is a woman.   Are there other female stormtroopers in any of the other Star Wars movies? What do we know about them? Do they have relationships, or children?


"Accept null hypothesis" or "fail to reject the null hypothesis"?

I'm trying to conduct a Student's t-test for a table of values while trying to follow the explanation and details found on . I understand that if the p-value is   <.01 then it's really significant >.05 it's not significant in between then we need more data   But on that page they seem to accept their null hypothesis no matter what the p-value is. So I'm really not understanding now when to accept or reject the null hypothesis.    When you do you accept or reject the null-hypothesis? Is it true that you are never supposed to accept your null hypothesis, but rather reject or fail to reject the null?


In general, how to determine the cardinality of the set of expression over a language?

For a given language L, with its set of variables $V$, function symbols $F$, relation symbols $R$. Once we are given the cardinality of $V$, $F$, $R$. Is there any way to define the cardinality of the set of expressions over this language?   I think maybe there can be a systematic way to find the cardinality (which may be very messy, but if it is such a way to deal with that, I really wish to learn about it also). And also I expect to learn (if there are) some useful tricks to determine it simply use the relation of the size of the set of expressions and the size of finite strings (which can be find much easily in this related question below).  Related question:      Both of above seems talked about the set of finite strings  So could someone give some way to determine the size of the set of expression? Any help will be appreciate.


Convert from digit number to hex string with zero leading digit

Is there a built-in Python function that convert from digit number to hex string with zero leading digit?  I wrote her:  def convert_to_hex_string(number):     number = format(number, 'x')     if len(number) == 1:         number = '0' + number     return number  >>> convert_to_hex_string(7) '07' >>> convert_to_hex_string(10) '0a' >>> convert_to_hex_string(11) '0b' >>> convert_to_hex_string(666) '29a'   but I was wondering could already have a built-in in Python (analogue .toString("X2") in C#)


Suppose I have a list of multi-part questions and each question has a QuestionNumber like 1, 1a,1b,2,2a and so on. I want to fetch a list of questions from the database using linq-to-entities, but ordered by QuestionNumber. The problem is that rather than using the correct order, it will use lexicographic ordering like   1 11 11a 11b 1a 1b 2 22   What I have so far is a custom comparer:  public class QuestionCompare : IComparer<Question> {     public int Compare(Question x, Question y)     {         string a = x.QuestionNumber;         string b = y.QuestionNumber;          if (a == b)         {             return 0;         }          int aInt;         bool aBool = Int32.TryParse(new String(a.Where(Char.IsDigit).ToArray()), out aInt);         int bInt;         bool bBool = Int32.TryParse(new String(b.Where(Char.IsDigit).ToArray()), out bInt);         if (aBool)         {             if (bBool)             {                 if (aInt > bInt)                 {                     return 1;                 }                 else if (aInt < bInt)                 {                     return -1;                 }                 else                 {                     string aLetter = new String(a.Where(Char.IsLetter).ToArray());                     string bLetter = new String(a.Where(Char.IsLetter).ToArray());                     return StringComparer.CurrentCulture.Compare(aLetter, bLetter);                 }             }             else             {                 return 1;             }         }         else         {             if (bBool)             {                 return -1;             }             else             {                 return StringComparer.CurrentCulture.Compare(a, b);             }         }          return 0;     } }   And you can call Array.Sort(questionArray,new QuestionCompare()) to put the questions in the correct order.  However, I feel like this is a common and well defined order so I'm wondering if there are better implementations, perhaps even something built in to the .Net framework.


The square of an integer is congruent to 0 or 1 mod 4

This is a question from the free Harvard online abstract algebra .  I'm posting my solutions here to get some feedback on them.  For a fuller explanation, see  post.  This problem is from assignment 6.  The notes from this lecture can be found .     a) Prove that the square $a^2$ of an integer $a$ is congruent to 0 or 1 modulo 4.   b) What are the possible values of $a^2$ modulo 8?   a) Let $a$ be an integer. Then $a=4q+r, 0\leq r<4$ with $\bar{a}=\bar{r}$.  Then we have $a^2=a\cdot a=(4q+r)^2=16q^2+8qr+r^2=4(4q^2+2qr)+r^2, 0\leq r^2<4$ with $\bar{a^2}=\bar{r^2}$.  So then the possible values for $r$ with $r^2<4$ are 0,1.  Then $\bar{a^2}=\bar{0}$ or $\bar{1}$.  b) Let $a$ be an integer. Then $a=8q+r, 0\leq r<8$ with $\bar{a}=\bar{r}$.  Then we have $a^2=a\cdot a=(8q+r)^2=64q^2+16qr+r^2=8(8q^2+2qr)+r^2, 0\leq r^2<8$ with $\bar{a^2}=\bar{r^2}$.  So then the possible values for $r$ with $r^2<8$ are 0,1,and 2.  Then $\bar{a^2}=\bar{0}$, $\bar{1}$ or $\bar{4}$.  Again, I welcome any critique of my reasoning and/or my style as well as alternative solutions to the problem.  Thanks.


I'm trying to make a list of features songs have such as BPM, Rhythm, Time signature, etc. I need features that are measurable.


What's the difference between size_t and int in C++?

In several C++ examples I see a use of the type size_t where I would have used a simple int. What's the difference, and why size_t should be better?


Why is using a local constant faster than accessing a global constant

In [8]: %paste PRIME = 16777619 UINT32_MAX = 4294967295  # (2 ** 32) - 1 def fnv1a_32_global(string):     hashval = 2166136261     for character in string:         hashval ^= ord(character)         hashval = (hashval * PRIME) & UINT32_MAX     return hashval  In [9]: %timeit fnv1a_32_global(mystr) 1000000 loops, best of 3: 990 ns per loop   In [6]: %paste def fnv1a_32_local(string):     hashval = 2166136261     PRIME = 16777619     UINT32_MAX = 4294967295  # (2 ** 32) - 1     for character in string:         hashval ^= ord(character)         hashval = (hashval * PRIME) & UINT32_MAX     return hashval In [7]: %timeit fnv1a_32_local(mystr) 1000000 loops, best of 3: 967 ns per loop   I am trying to confirm (and understand why) initializing a local var on every function call and accessing it is faster than once initializing a global var and accessing it.  This result is consistent across several test attempts.  Additinal question: can this code be made even faster (I tried using a c-library pyfasthash. It is even slower than the above implementations)


Is the wifi password stored somewhere in windows-7?

One of my friend connected me to the wifi in our area . Now my computer automatically connects to that wifi. I don't need to enter the password. I wanted to browse internet using my android phone. Since i don't know the password i can't connect to the wifi network. Is there any file/folder where the password for the wifi is saved on windows-7 pc ?


Why do we use double hyphen in "tar --anchored" and single hyphen in "tar -b"?

Why do we use double hyphen in tar --anchored and single hyphen in tar -b?  I mean to say why some command line options have single hyphen (-) while some others have double (--)?  Also a git example:  git commit --amend git commit -a


How to start a process and leave it running using php?

I want to start a process which outputs to a text file. I want to be able to start it and have seperate button to stop it. I have tried using popen, exec, passthru but my understanding is they all wait till the process exits to return data to php? Is there any way i can just start  a process and leave it running. All i want returned is the pid. Here is what I have tried so far.  <?php $data=$_POST['data']; $args = escapeshellarg($data); $cmd = "./fw {$args}". " 2&>lg.log & echo $!"; passthru($cmd, $output);   $arr = array("pid"=>$output); echo json_encode($arr); /* $handle = popen('./fw {$args} 2>&1', 'r'); echo "'$handle'; " . gettype($handle) . "\n"; $read = fread($handle, 209600); echo $read; pclose($handle); */  ?>   Solution suggested in the linked question works with this  $cmd = "./fw {$args}". " >lg.log & echo $!"; exec($cmd, $output);   but if i want stderr redirect too and change it to  $cmd = "./fw {$args}". " 2&>lg.log & echo $!"; exec($cmd, $output);   it stops working. Then i get the return value for pid only after I kill the process.


How to get a 2D silhouette of a 3D mesh in Blender 2.8?

I would like to just take a 2D silhouette outline of a side of one of my 3D meshes. I located the question  but since it was made over a year ago, and I am using Blender 2.8, the script does not work for me. Any advice on how to update it? It seems to error out around this part:  copy = ob.copy() sil = bpy.data.meshes.new("silhouette") copy.data = sil scene.objects.link(copy) scene.objects.active = copy copy.select = True bm.to_mesh(sil)   Also, more importantly, how would I export the silhouette? Like it wouldn't save as an stl file.


ubuntu 20 printer hp laser jet p1566 the printer always give me the same message "printing stopped" printer worked in good condition with any another device has windows operating system


Imagine that I'm writing the Jordan form of a matrix and I know that the eigenvalue needs to appear 4 times in the diagonal (algebraic multiplicity is 4) and we need 2 Jordan blocks (geometric multiplicity is 2). Now how do I know the size of the blocks? It could be a 1x1 and 3x3 block ou two 2x2 blocks, right? Also in the first case how do I know which block comes first in the diagonal?


$$\sum_{n=2}^\infty\frac{(-1)^n}{\sqrt[3]{n}+ (-1)^{\frac{n(n+1)}{2}}}$$ None of convergence tests I know (Leibnitz, Dirichlet, Abel) works becaues of the denominator.  I know that sum of convergent series is convergent too and I tried using this information with no results.


Print message only if checkbox field is alter using form alter

I have created a checkbox in user edit using form alter and based checkbox state I want to print the message. For this I used below code  function module_form_user_profile_form_alter(&$form, &$form_state) {    $form['account']['checkbox'] = array(     '#type' => 'checkbox',     '#title' => 'Test check',    );    $form['#submit'][] = 'module_simplenews_unsubscribe'; }  //~ //Submit handler for Subscribe/unsubscribe newsletter. function module_simplenews_unsubscribe($form, &$form_state) {    if ($form['account']['checkbox']['#value'] == 0) {     drupal_set_message(t("You are checked"));   }  if ($form['account']['checkbox']['#value'] == 1) {      drupal_set_message(t("You are unchecked"));   } }   It works fine. When checkbox is checked/unchecked and user saves the profile it prints respective message. But when user doesn't modify this checkbox field and modify some other field and saves, again it prints message based on checkbox state.  I want to display the message only when checkbox field is modified. How can I achieve this?


how can I check integer overflow in C/C++?

I want to know how to determine overflow in C/C++. if my input for integer is 9999999999999999999999 , It is a very big number and if I run the below code I will get a garbage output.   #include <stdio.h>  int main(){     int a;     scanf("%d",&a);     printf("%d",a);     return 0; }   Is there any way to know , if the input is a big number, I can output "Input is too big" .  Note that, I have already checked  . But the question is different from my one.


How to divide list into 3 sections that are equal in length(sort of) - Python

Ok so like lets say a list of length n. n>= 5  I have to choose two index's in the list that will be the cutting point. These 2 elements will be removed as the list will become 3 new lists.  There will be 3 sections: A , B and C. A must be bigger or equal to B. and B must be bigger or equal to C. The difference between all 3 sections can only be a maximum of one. With these restrictions what is the formula in finding the 2 index's of a list with the length n?   For Example a list with 5 elements. The 2 index's would be index 1 and index 3.  [1,2,3,4,5] = > [1] [3] [5] with 2 and 4 being the elements that were removed due to the specific index's being cut.  A bigger list with the length of 19 for example  [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] The index's that will be the cutting points are index 6 and index 13.   The 3 new formed lists will be [1,2,3,4,5,6] [8,9,10,11,12,13] and [15,16,17,18,19]. You can see that the first two are bigger than the last one as the rules state and the difference in length between each list is not bigger than 1.


I'm trying to find an alternative to the standard tombstone qed symbol for more informal papers. I initially thought of an empty square with Pub written inside, but what would actually be better would be a small beer mug symbol. (much like the one found in this set of icons )  Unfortunately there doesn't seem to such a symbol in the comprehensive latex symbol list (although many funny symbols can be found there). Has anyone thought about this? Is there any quick-and-dirty solution?


Solve congruence system $\ x\equiv m_i-1 \pmod{m_i}\,$ for $\,i = 1,\ldots, k$

Find natural number $x$ so that $$\begin{align}x&\equiv 9\pmod{10}\\ x&\equiv8\pmod9\\ &\ \ \vdots\\ x&\equiv 1\pmod2\end{align}$$


Improper integral of sin(x)/x from zero to infinity

I was having trouble with the following integral: $\int_{0}^\infty \frac{\sin(x)}{x}dx$. My question is, how does one go about evaluating this, since its existence seems fairly intuitive, while its solution, at least to me, does not seem particularly obvious.


Construct an algorithm to find the multiple of A such that A%B is maximized

Suppose we have two numbers A and B. We need to find a multiple of A such the A % B is maximized One such solution can be to traverse B multiples of A? is there any other soltuion?(In case B is huge)  Suppose A=3 and B=10. then 10 multiples of 3 are 3,6,9.......30.   Max remainder will be 9%10=9.  Suppose A=14 and B=11 then 11 multiples of 14 are 14,28..........140,154.  Then max remainder 98%11=10 .  Is there any more effective way to find this?


I am creating a game in unity and have run into a problem when resetting the speed to 0.   The game uses multiple throttle levels: -2 -1 0 1 2. When set to a throttle level the object is meant to speed up to a set speed. This works but when I come to reset it to 0 the speed sets its self to 0.0999999 even though 0 is set.   How can I fix this?   using UnityEngine; using System.Collections; using System;  public class Script_Control : MonoBehaviour { public static float speedLvL; public static float speed; public static float health; public static float manoverablity; public static float tarSpeed; public static float curSpeed;            // Use this for initialization void Start () {  //setting per ship stats speedLvL = 0F; speed = .25F; health = 25F; manoverablity = .25F; //General Stats tarSpeed = 0F; curSpeed = 0F;  }  // FixedUpdate is called once per Time void FixedUpdate () {     Debug.Log(curSpeed); //setting speed  if (speedLvL == 0F){     tarSpeed = 0.00000F; } if (speedLvL == 1F)  {     tarSpeed = speed/2F; } if (speedLvL == 2F)  {     tarSpeed = speed; } if (speedLvL == -1F)  {     tarSpeed = -speed/5F; } if (speedLvL == -2F)  {     tarSpeed = -speed/2.5F; }  if (curSpeed < tarSpeed){     curSpeed += .1F; } if (curSpeed > tarSpeed){     curSpeed -= .1F; }     transform.Translate(curSpeed, 0, 0);  } void Update(){      if (Input.GetAxis("Throttle") > 0 && speedLvL <= 1 &&  speedLvL >= -2){         speedLvL = speedLvL+1;               DateTime t = DateTime.Now;          DateTime tf = DateTime.Now.AddSeconds(.25);         while (t < tf)         {             t = DateTime.Now;         }      }         if (Input.GetAxis("Throttle") < 0 && speedLvL <= 2 &&  speedLvL >= -1){         speedLvL = speedLvL-1;         DateTime t = DateTime.Now;          DateTime tf = DateTime.Now.AddSeconds(.25);         while (t < tf)         {             t = DateTime.Now;         }     }      if (Input.GetAxis("Stearing") < 0){         transform.Rotate(Vector3.forward* Time.deltaTime, manoverablity );      }     if (Input.GetAxis("Stearing") > 0){         transform.Rotate(Vector3.forward* Time.deltaTime, -manoverablity);      } }    }   `


I would like to change the function of scroll lock. After pressing scroll lock, it should turn off the screen (and of course no backlight). I have tried the following:   have set the custom command "xset dpms force off" for the scroll lock in the keyboard shortcuts in ubuntu system. But no effect. have tried also to set by script using autokey (which I use for other purposes). But no effect.   My target is to make it simple, and not to write some big scripts and to let them load every time I want the screen off.  I have read something about remaping through xmodmap, but... If I use xev in terminal, then after pressing scroll_lock:     FocusIn event, serial 38, synthetic NO, window 0x6200001,       mode NotifyUngrab, detail NotifyAncestor      KeymapNotify event, serial 38, synthetic NO, window 0x0,       keys:  2   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0              0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0         FocusOut event, serial 38, synthetic NO, window 0x6200001,       mode NotifyNormal, detail NotifyNonlinear   ... and there is no info about keycode...  kind regards  Pepo


prove the following inequality using am gm hm or weirstrass etc

For $a_0,a_1,a_2,......,a_n \in R, \,\, a_0<a_1<a_2<....<a_n$ show that $$ \frac n{a_1-a_0}+\frac {n-1}{a_2-a_1}+....+\frac 1{a_n-a_{n-1}} \ge \sum_{k=1}^n \frac {k^2}{a_k} $$ i recently studied inequalities am gm hm , tchebychev, weirstrass, cauchy schwarz. i am trying to solve some questions i don't know how to start on this one can someone please help me on this.


I have an API response which returns a date time object in String. I need to convert it into a UTC Datetime object to compare with the current datetime.  How do I convert this to an UTC DateTime object?  received    "2019-03-22T06:35:57Z"


How can I install both Windows 7 and Ubuntu 14.04?

I have an 80 GB hard drive and 8 GB of RAM. Do I need to make a partition to install Ubuntu 14.04 and Windows 7 alongside each other?   I have tried but I could not do it. Please help me out.


If $a_n \to 0$ then $(a_1+\cdots+a_n)/n \to 0$

Where $a_n \in C$, intuitively I think this must be true as if are taking an average of almost all arbitrarily small numbers then the average will be arbitrarily small.   let $\epsilon>0, \exists N:|a_n|<\epsilon, \forall n>N$ $$ |(a_1+\cdots+a_n)/n|<\epsilon$$ $$|a_1+\cdots+a_N+\cdots+a_n|<e n$$  I know this is wrong but this was what I was thinking $$|a_1+\cdots+a_N|+(n-N)\epsilon<en$$ Could I have a rough hint on a how to better estimate the value of $ |(a_1+\cdots+a_n)/n|$


Is cross-posting a question on multiple Stack Exchange sites permitted if the question is on-topic for each site?

It is possible to migrate a question from one Stack Exchange site to another by closing, but if I have a question that I think is on-topic for multiple Stack Exchange sites, is it OK to post it on both (multipost)?   For example, I have a question that's earned me the tumbleweed badge on SO and I'm not sure what the best thing to do with it is. It's about a web server so it might be answerable on Server Fault but it's really more of a programming thing, hence the posting the question on Stack Overflow.    Is there any way to make the question visible on multiple sites (crosspost) and then accept the answer wherever it came from?


HashSet.Contains is fast but I need to search for multiple properties of an object

I have a     var  itemList = new List<Item>()    and a     var  searchSet = new HashSet<TestItem>(new TestItemComparer());   For each element in the itemList I look for its existance in the searchSet via the Number property.  I search like this: ( The item.Numer is an enumerated element of the itemList)  var isFound = searchSet.Contains(new TestItem{ Number = item.Numer });   public class TestItemComparer: IEqualityComparer<TestItem>     {         public bool Equals(TestItem x, TestItem y)         {             return x.Number == y.Number;         }          public int GetHashCode(TestItem obj)         {             return obj.Number.GetHashCode();         }     }   The reason why my searchSet has a comlex type TestItem and not integer is because I still want to combine my search with some other properties on the TestItem class.  How can I still use this amazing fast HashSet.Contains method but combine the Number search with other properties?  Should I change my TestItemComparer for this?


Where Did the Atlantis Gate Address Come From?

In the first episode of Stargate Atlantis, the only mention of where the 8-symbol address came from, was Daniel Jackson mentioning, "recently, we've been able to determine the...". But how, exactly, did they figure out that the address for Atlantis was 8 symbols, let alone what the 8th symbol was? Was it stored in the Ancient outpost?


How to make a button appear as if it is pressed?

Using VS2008, C#, .Net 2 and Winforms how can I make a regular Button look "pressed"? Imagine this button is an on/off switch.  ToolStripButton has the Checked property, but the regular Button does not.


Why does find -mtime +1 only return files older than 2 days?

I'm struggling to wrap my mind around why the find interprets file modification times the way it does.  Specifically, I don't understand why the -mtime +1 doesn't show files less than 48 hours old.   As an example test I created three test files with different modified dates:   [root@foobox findtest]# ls -l total 0 -rw-r--r-- 1 root root 0 Sep 25 08:44 foo1 -rw-r--r-- 1 root root 0 Sep 24 08:14 foo2 -rw-r--r-- 1 root root 0 Sep 23 08:14 foo3   I then ran find with the -mtime +1 switch and got the following output:  [root@foobox findtest]# find -mtime +1 ./foo3   I then ran find with the -mmin +1440 and got the following output:   [root@foobox findtest]# find -mmin +1440 ./foo3 ./foo2   As per the man page for find, I understand that this is expected behavior:   -mtime n         File’s  data was last modified n*24 hours ago.  See the comments         for -atime to understand how rounding affects the interpretation         of file modification times.   -atime n        File  was  last  accessed n*24 hours ago.  When find figures out        how many 24-hour periods ago the file  was  last  accessed,  any        fractional part is ignored, so to match -atime +1, a file has to        have been accessed at least two days ago.   This still doesn't make sense to me though.  So if a file is 1 day, 23 hours, 59 minutes, and 59 seconds old, find -mtime +1 ignores all that and just treats it like it's 1 day, 0 hours, 0 minutes, and 0 seconds old?  In which case, it's not technically older that 1 day and ignored?   Does... not... compute.


You cannot contract "there are"!!. Right or Wrong?

claims that  Contractions The contraction of there is is there's.  There's a good song on the radio. There's only one chocolate left in the box.  You cannot contract there are.  There are nine cats on the roof. There are only five weeks until my birthday.   So, can we not say There're nine cats on the roof?


I have more than 20 filters, how can I easily reorder them?


Can't use metacity themes in gnome flashback session (metacity) Ubuntu 16.04

I'm using the gnome flashback session with metacity window manager, but I can't change to any metacity theme in any of the tweaking tools, as they're not even appearing in the lists. Is there anything I can do?


After the events of the final episode of *Game of Thrones*, who rules Casterly Rock now?

Now that Tyrion is no longer a fugitive of the Crown and as the most senior successor to be ruler of Casterly Rock, can he be head of House Lannister as well as being Hand of the King?