Why is the error function defined as it is?

$\newcommand{\erf}{\operatorname{erf}}$ This may be a very naïve question, but here goes.  The  $\erf$ is defined by $$\erf(x) = \frac{2}{\sqrt{\pi}} \int_0^x e^{-t^2}dt.$$ Of course, it is closely related to the normal cdf $$\Phi(x) = P(N < x) = \frac{1}{\sqrt{2\pi}} \int_{-\infty}^x e^{-t^2/2}dt$$ (where $N \sim N(0,1)$ is a standard normal) by the expression $\erf(x) = 2\Phi(x \sqrt{2})-1$.  My question is:     Why is it natural or useful to define $\erf$ normalized in this way?   I may be biased: as a probabilist, I think much more naturally in terms of $\Phi$.  However, anytime I want to compute something, I find that my calculator or math library only provides $\erf$, and I have to go check a textbook or Wikipedia to remember where all the $1$s and $2$s go.  Being charitable, I have to assume that $\erf$ was invented for some reason other than to cause me annoyance, so I would like to know what it is.  If nothing else, it might help me remember the definition.  Wikipedia says:     The standard normal cdf is used more often in probability and statistics, and the error function is used more often in other branches of mathematics.   So perhaps a practitioner of one of these mysterious "other branches of mathematics" would care to enlighten me.   The most reasonable expression I've found is that $$P(|N| < x) = \erf(x/\sqrt{2}).$$ This at least gets rid of all but one of the apparently spurious constants, but still has a peculiar $\sqrt{2}$ floating around.


How to maintain order of key/value pairs in dictionary of python?

I am creating a module in which a dictionary is used. This dictionary contains some key/value pairs, whose order must be preserved when using in other modules. But whenever I iterate over dictionary and print the keys, the keys are not in the order in which they key/value pairs are inserted.  So my question is how should I preserve the order of key/value pair in a dictionary?  Any help will be highly appreciated...  Thanx in advance...


sculpting and connecting from different bodyparts

I am beginner and sculpt a body at the moment. I guess my way wasn't very effective. I created a body with different body parts. Each body part is a separate object. I sculpt mostly and I realized I wanna connect the different object to sculpt in a better way. This should be the way anyway at the end. I have no idea how to do this. I used a subdivision surface mod and it is just.. messy. In a old video I have seen there is a kind of bridge addon? I would be happy for any recommendation or tip. I attach a picture.


Can Classical Mechanics and/or Quantum Mechanics explain the formation of a single hydrogen atom?

If we have a single electron and a single proton, Can Classical Mechanics and/or Quantum Mechanics explain why the electron revolves around the proton and not the proton around to electron?


R-4.0.1 Not sure I understand this message: Warning message: In proj4string(x) : CRS object has comment, which is lost in output

Context: I want to store the TIFF data to use it for running a linear regression model later on. Ultimate goal: Create a carbon map using field data as a basis. Libraries: library(sp) library(raster) library(tidyverse) library(rgdal)  plotcoord <- SpatialPointsDataFrame(AGCplot[,3:4], AGCplot[,1:2],proj4string=CRS('+proj=longlat'))  pspcoord<-spTransform(plotcoord, CRS('+proj=utm +zone=21')) #Omzetten naar UTM21N (= S1) plot(pspcoord)  s1 <- stack('Some.tif')  colnamen = c("plotid","AGC","B2","B3","B4","B5","B6","B7","B8","B8A","B11","B12","NDVI","NDWI","MMRI","IRECI","MASI","VV","VH")  s1_e <- extract(s1,pspcoord,method='bilinear')  Upon extraction I get the following message: Warning message: In proj4string(x) : CRS object has comment, which is lost in output


It seems that Stackoverflow has lost one of my achievement event, as I'm not sure, I just describe what I saw.   I answered this  today  I received a "vote up" I received the "accept" achievement event and get my new reputation I saw the "accept" flag on the  I fresh the  minutes later, the "accept" flag gone and my reputation reduced to former value I checked the "achievement" events, the one I received at step 3 is gone, the one I received at step 2 remains   There is another explanation besides Stackoverflow got bug: The author withdrawn the accept operation; the effect of withdraw event is not add another event but delete the related "accept" event. I never withdrawn the accept operation so I am not sure about that explanation.  Actually, I'm a little curious about the process of the 'accept' operation. I think it's more like, instead of change the reputations instantly, the operation just write an event to a distributed queue, then a realtime job consume the event from the queue, finish the actions including add the reputation of author and answerer, push a notification to author and answerer, etc.


Using a Unicode Character in the Document

I would like to use star and crescent (U+262A) emoji in my document, even though I have read several articles in this environment, I couldnt realize how to do it. Please can anyone give me a hand? Thanks in advance


Evaluate $\int_0^{\infty}\frac{\ln x}{x^a(x+1)}dx$ where $0<a<1$

I'm trying to compute this integral, $$\int_{0}^{\infty}\frac{\ln x}{x^{a}(x+1)}dx \hbox{ where } 0<a<1$$ I drew a typical Pacman contour with branch cut at positive real axis. Then, we have $$\int_{\Gamma}\frac{\ln z}{z^{a}(z+1)}dz=\left(\int_{L_{1}}+\int_{L_{2}}+\int_{C_{R}}+\int_{C_{\epsilon}}\right)\frac{\ln z}{z^{a}(z+1)}dz$$ The function has a pole at $z=-1$. Then, by residue theorem, the whole integral becomes  \begin{align*} \int_{\Gamma}\frac{\ln z}{z^{a}(z+1)}dz&=2\pi i\text{res}(\frac{\ln z}{z^{a}(z+1)};-1)\\&=2\pi i\lim_{z\rightarrow-1}(z+1)\frac{\ln z}{z^{a}(z+1)}\\&=2\pi i\lim_{z\rightarrow-1}\frac{\ln z}{z^{a}}\\&=2\pi i\frac{\ln e^{i\pi}}{e^{i\pi a}}\\&=2\pi i\frac{\ln1+i\pi}{e^{i\pi a}}\\&=-\frac{2\pi^{2}}{(e^{i\pi})^{a}} \end{align*} On $L_1$, $z=xe^{i\epsilon}$ where $\epsilon\leq x\leq R$  On $L_{2}$, $z=xe^{i(2\pi-\epsilon)}$ where $\epsilon\leq x\leq R$  On $C_{R}$, $z=Re^{i\theta}$ where $\epsilon\leq\theta\leq2\pi-\epsilon$  Lastly on On $C_{\epsilon}$, $z=\epsilon e^{i\theta}$ where $\epsilon\leq\theta\leq2\pi-\epsilon$  So I tried to compute them separately and I anticipate the curves will both go to $0$ by ML inequality, and two linear integrals will consist of the term $\int_{0}^{\infty}\frac{\ln x}{x^{a}(x+1)}dx$ and hence simply solve for it. But I'm having trouble physically solving it out. I think the log is throwing me off. Can anybody please help me?


What's the /summon syntax to summon equipped mobs

What I need to type when I want to summon "equipped" mobs? I want to summon headless zombies(wearing air on their head). So, can you tell me what to type in the chat(after "summon zombie") for each part of the body's equipment, please? Edit:Tell me also on other parts of the body.


Delete Javascript object item adding null value

I have an javscript object finalTitleList =[{"Title":"ffd","Iscompleted":"","Id":0},                  {"Title":"fdfmdbk","Iscompleted":"","Id":1},                  {"Title":"fdf,d","Iscompleted":"","Id":2}]  Suppose i like to delete an 2nd item using delete finalTitleList[1], after deletion it delete the item but length is not updated(snapshot attached: contain only 2 item but showing length 3). So when i am adding that object in localstorage using localStorage.setItem("TaskTitleList16", JSON.stringify(finalTitleList));  On place of deleteditem it shows null. I want to completely remove that item, please help me.


R - Lasso Regression - different Lambda per regressor

I want to do the following:  1) OLS regression (no penalization term) to get beta coefficients $b_{j}^{*}$; $j$ stands for the variables used to regress. I do this by   lm.model = lm(y~ 0 + x) betas    = coefficients(lm.model)   2) Lasso regression with a penalization term, the selection criteria shall be the Bayesian Information Criteria (BIC), given by  $$\lambda _{j} = \frac{\log (T)}{T|b_{j}^{*}|}$$  where $j$ stands for the variable/regressor number, $T$ for the number of observations, and $b_{j}^{*}$ for the initial betas obtained in step 1). I want to have regression results for this specific $\lambda_j$ value, which is different for each regressor used. Hence if there are three variables, there will be three different values $\lambda_j$.   The OLS-Lasso optimization problem is then given by  $$\underset{b\epsilon \mathbb{R}^{n} }{min} = \left \{ \sum_{t=1}^{T}(y_{t}-b^{\top} X_{t}  )^{2} + T\sum_{j=1}^{m} ( \lambda_{t}|b_{j}| )\right \}$$  How can I do this in R with either the lars or glmnet package? I cannot find a way to specify lambda and I am not 100% sure if I get the correct results if I run   lars.model <- lars(x,y,type = "lasso", intercept = FALSE) predict.lars(lars.model, type="coefficients", mode="lambda")   I appreciate any help here.    Update:  I have used the following code now:  fits.cv = cv.glmnet(x,y,type="mse",penalty.factor = pnlty) lmin    = as.numeric(fits.cv[9]) #lambda.min fits    = glmnet(x,y, alpha=1, intercept=FALSE, penalty.factor = pnlty) coef    = coef(fits, s = lmin)   In line 1 I use cross validation with my specified penalty factor ($\lambda _{j} = \frac{\log (T)}{T|b_{j}^{*}|}$), which is different for each regressor.  Line 2 selects the "lambda.min" of fits.cv, which is the lambda that gives minimum mean cross-validation error. Line 3 performs a lasso fit (alpha=1) on the data. Again I used the penalty factor $\lambda$. Line 4 extracts the coefficients from fits which belong to the "optimal" $\lambda$ chosen in line 2.  Now I have the beta coefficients for the regressors which depict the optimal solution of the minimization problem   $$\underset{b\epsilon \mathbb{R}^{n} }{min} = \left \{ \sum_{t=1}^{T}(y_{t}-b^{\top} X_{t}  )^{2} + T\sum_{j=1}^{m} ( \lambda_{t}|b_{j}| )\right \}$$  with a penalty factor $\lambda _{j} = \frac{\log (T)}{T|b_{j}^{*}|}$. The optimal set of coefficients is most likely a subset of the regressors which I initially used, this is a consequence of the Lasso method which shrinks down the number of used regressors.  Is my understanding and the code correct?


Why can't I filter on IS NOT NULL in this query

I am trying to filter NULL results in my query but it is giving me an error.  My query:  SELECT   cnt.id,   cnt.title,   cnt.introtext,   cnt.fulltext,   cnt.ordering,   cnt.images,   cnt.alias,   cnt.state,   f.item_id,   MAX(CASE     WHEN f.field_id = 3 THEN f.value   END) AS inslider FROM snm_fields_values f JOIN snm_content cnt   ON cnt.id = f.item_id WHERE cnt.state = 1 AND f.value = 'ja' AND inslider IS NOT NULL GROUP BY f.item_id ORDER BY f.item_id, inslider   This query gives me:      Unknown column 'inslider' in where clause.   inslider is the row that returns a null value, when I remove the IS NOT NULL line from the above query, my result is:    ( I know an image is bad instead of text but I couldn't get it formatted nicely on SO. )  How can I filter a result if it returns NULL on inslider (which is an alias).


biblatex: Use the shorttitle of an xref in bibliography

I would like to show only the shorttitle of an xref in the the bibliography entry referrring to it. Currently it shows the full information:  MWE:  \documentclass{book} \usepackage{polyglossia} \setmainlanguage[spelling=new,babelshorthands=true]{german} \usepackage[autostyle]{csquotes} \usepackage[style=authortitle-dw, edsuper=true, namefont=smallcaps, useprefix=true, ibidemfont=smallcaps, idemfont=smallcaps, idembibformat=dash, shorthandibid=true, backref=false, backrefstyle=none, hyperref=true, isbn=false, backend=biber, citereset=chapter, bibencoding=utf8]{biblatex} \DeclareFieldFormat{pages}{#1} \DeclareFieldFormat{page}{#1} \DeclareNameAlias{sortname}{family-given} \DeclareNameAlias{default}{family-given} \DeclareNameAlias{byeditor}{family-given} \DeclareNameAlias{bytranslator}{family-given} \DefineBibliographyStrings{german}{     andothers = {et\,al\adddot},     editor    = {Hg\adddot} ,     editors   = {Hg\adddot} } \urlstyle{same} \renewbibmacro*{publisher+location+date}{%     \setunit{\addperiod\space}%     \printlist{location}%     \iflistundef{publisher}     {\setunit*{\space}}     {\setunit*{\addcolon\space}}%     \printlist{publisher}%     \setunit*{\addcomma\space}%     \usebibmacro{date}%     \newunit} \usepackage{filecontents} \begin{filecontents}{\jobname.bib}      @book{b2,         year = {2014},         title = {Redefreiheit: Öffentliche Debatten der Bevölkerung im Herbst 1989},         address = {Leipzig},         edition = {1. Aufl.},         publisher = {Leipziger Uni-Vlg},         isbn = {386583888X},         editor = {Ahbe, Thomas and Stiehler, Volker and Hofmann, Michael},         shorttitle = {Redefreiheit}     }      @incollection{bauer,         crossref   = {schwobel},         author     = {Bauer, Gisa},         title      = {Transformationen des Religiösen},         subtitle   = {Die historisch-materialistische Geschichtsschreibung in der DDR als Heilsgeschichte},         shorttitle = {Transformationen}     }        @collection{schwobel,         title      = {Geschichte und Gott: XV. Europäischer Kongress für Theologie},         address    = {Leipzig},         year = {2014},         number     = {39},         series     = {VWGTh},         editor     = {Schwöbel, Christoph},         shorttitle = {Geschichte},     }      @book{bulischop.2006,         author     = {Bulisch, Jens},         year       = {2006},  url = {http://www.kirche-mv.de/fileadmin/ELLM-Downloadtexte/Beste-60JahreMKZ.pdf},  urldate = {2015-07-28},         title      = {Evangelische Presse in der DDR},         address    = {Göttingen},         number     = {43},         publisher  = {Vandenhoeck und Ruprecht},         isbn       = {3525557442},         series     = {AKZG},         shorttitle = {Presse},     } \end{filecontents}  \addbibresource{\jobname.bib} \begin{document}     text \footcite{bulischop.2006} text.     text \footcite{bauer} haha.      \printbibliography \end{document}     Instead of the text circled in red I would like to have:  SCHWOBEL, Christoph (Hg.): Geschichte And additionally I would like to have the referenced entry also in the bibliography.


Why are "fun" and "hulk" phonetically transcribed with the same vowel but pronounced differently?

I see many words in English have the same phonetics but I don't know why they sound different.  It means if we read the phonetics and pronounce, it will be wrong. Here are the examples.   fun : /fʌn/  hunt : /hʌnt/ luck : /lʌk/  hulk : /hʌlk/ bulk : /bʌlk/   As you can see, the vowels in the words above are spelled with the same letter ("u") and transcribed with the same phonetic symbol ("ʌ"), but all of them sound different.  Fun and hunt sound similar, but they sound quite different from hulk or bulk.  If I pronounce the u vowel on hulk ~ luck or fun, it might be wrong   Fun  Hulk  Or listening to Robert Downey Jr    Why? What's the role of the phonetic symbol "ʌ" and how do I pronounce these words correctly based on reading phonetics?


Recovering data from a laptop that cannot boot

I have a laptop with Linux Mint installed. I had a power outage, and currently, it cannot boot - it shows grub rescue when booting.  I don't mind formatting and re-installing the system, but there are a couple of files which I'd like to recover.  I ran Boot-Info from a live USB, but it didn't help. Here are the logs:   Can you please help me with this? I'm not familiar enough with Linux to understand much from the logs.


How to let the people know that my document was produced with/on LaTeX

I want to put a LaTeX "notice" in my document, something like "This document was created using LaTeX". However, I think the words in italic might be wrong: should it be "created", or "produced", or what?, and should it be "using", or "on", or what?


Forming SOAP header through apex class if the WSDL provided has no information regarding the header

<soapenv:Header>   <wsse:Security SOAP-ENV:mustUnderstand="1" xmlns:SOAP-ENV="SOAP-ENV">      <wsse:UsernameToken wsu:Id="UsernameToken-1" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">         <wsse:Username>oneview</wsse:Username>         <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">oneview123</wsse:Password>      </wsse:UsernameToken>   </wsse:Security>     Here is how my header is structured in request .By default when my stub is generated from WSDL no information regarding  header in WSDL .So is there any code in apex i can start and include in my stub class and create this kind of header.  Update:  <wsp:Policy wsu:Id="UsernameToken" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" xmlns:wsp="http://schemas.xmlsoap.org/ws/2004/09/policy">     <wsp:ExactlyOne>         <wsp:All>             <sp:SupportingTokens xmlns:sp="http://docs.oasis-open.org/ws-sx/ws-securitypolicy/200702">                 <wsp:Policy>                     <sp:UsernameToken sp:IncludeToken=".../IncludeToken/AlwaysToRecipient"/>                 </wsp:Policy>             </sp:SupportingTokens>         </wsp:All>     </wsp:ExactlyOne> </wsp:Policy>   The WSDL has wsp and policy .Do WSDL to apex support this.Any help appreciated


Let $f(z)$ be a holomorphic function on the unit disk $\mathbb{D}$ such that $\lvert f(z)\rvert \leq \frac{1}{1-\lvert z\rvert}$ for all $z\in \mathbb{D}$. Show that $\lvert f'(z)\rvert \leq \frac{4}{(1-\lvert z\rvert)^2}$ for all $z\in \mathbb{D}$. The only inequality that I know that looks sort of like this is the Schwarz-Pick lemma, but we do not have that $f(z)$ has range contained in $\mathbb{D}$, so we can not use this as is. I have also tried using the Cauchy Integral formula to estimate \begin{equation}\lvert f'(z)\rvert =\lvert \frac{1}{2\pi}\int_{\lvert \zeta\rvert =r}\frac{f(\zeta)}{(\zeta-z)^2}d\zeta\rvert\end{equation} for $1>r>\lvert z\rvert$, but I ended up with something going to infinity on the RHS as I tried to take $r\to1$. At this point I'm sort of throwing ideas at a wall, so if someone could give me a small hint, that would be excellent.


Are units in English singular or plural?

I am a little bit confused about using units in English, sometimes I hear that people use singular units for plural things, sometimes they use plural ones. Which one is correct?   3 meter(s) long? during a 2 week(s) period? 0.5 dollar(s)


How long can cooked food be safely stored at room/warm temperature?

If I leave fully-cooked food (particularly meat) out at warm temperature - say on the counter or in a crock pot that's been turned off -  how long will it stay safe to eat?  Does it make any difference if I re-cook the food afterward?


I see related questions such as:   and  But does Superman need to eat?   And if so, what happens if he doesn't?


I need to use InfoStat for one of my classes, but there's only a Windows version available for download. I've tried using it through Wine, but it doesn't work properly. Is there any software available for Linux that offers the same (or at least similar) features? (Please keep in mind that I've just moved to Linux and I'm slowly learning my way around it). Thanks!


Downloading third party softwares in local repository using apt-mirror

Currently I have setup a local repository using apt-mirror to establish a offline local repository for Ubuntu 16.04.  However, only the official packages are downloaded. I would like to make the third party libraries like Google Chrome, OwnCloud etc. to be also available in my offline local repository.  What changes shpuld I make in the file mirror.list so that apt-mirror can do the job?


3 Letters of Recommendation for Bio Grad School

I'm a rising senior in college and I'm looking into grad programs in biology. For the Letter of Recommendation requirement I have found that usually 3 are required. Currently I can only think of 2 mentors who are in the field of study I would like to go into who can write strong letters. Is it bad if the third came from a professor in a completely different field, or as I like to think of as the humanities research that interprets the science research I'm interested in? Thank you! Or should I ask one of the post-docs in the lab I work with (in addition to the PI of the lab) since they are working in the relevant field?


How could Harry do Lumos without touching his wand in OotP?

I was wondering how come Harry was able to do Lumos without touching his wand in OotP. I remember that he tried to do magic without his wand before (or afterwards), and he couldn't.  Sorry if this is a repeat question. I couldn't find the answer anywhere.


Prove that the group isomorphism $\mathbb{Z}^m \cong \mathbb{Z}^n$ implies that $m = n$

Let $m$ and $n$ be two nonnegative integers. Assume that there is a group isomorphism $\mathbb{Z}^m \cong \mathbb{Z}^n$. Prove that $m = n$.   I tried using a contrapositive, ($m \neq n$ implies $\mathbb{Z}^m \ncong \mathbb{Z}^n$), and I think the problem is that there won't be a homomorphism, but did not get anywhere. Is there a better approach to this problem?


Single site SE flair not displaying the correct icon

I'm having reports from users of my community that the peoples profile flairs are displaying the old beta icon instead of the correct one for their community.  Here is what I see:    The combined flair seems to be unaffected.  Even after clearing my browser cache, I see this on Area 51:    It seems to be affecting Beta and Graduated sites, but not Meta.SO for some reason:


Drugging Robert Michael Fischer on Flight

In Inception, why does Cobb slip the sedative into Robert's glass of water himself, taking considerable amount of risk at getting caught? Why didn't the Air hostess get the pre-drugged water for Fischer? Is there any reason for this?


Highlighted text is not readable in text editor with dark mode on Ubuntu 20.04 LTS

I have an issue with the text editor on Ubuntu 20.04. With dark mode enabled, the highlighted text is not readable.   Is there any way to fix this?


Modify all bash commands through a program before executing them

I am trying to create a program which require such feature. The flow will be like:   User enter a bash command User hit the enter My script will get command, current directory,.. as variables. Program can optionally modify the command. Modified command will get executed normally.   Is there any way to do this?  Note: I need this for my personal use, I am not going to distribute this program.


Why does my user number show up in the search box when clicking my profile information?

Hey all-  I just noticed that if you click on your username on the top bar, when your profile shows up, in the search bar at the top you'll find an explicit search for your user account.  For my meta account, for example, I see user:157031 whenever I click on my profile.  Is this deliberate?  If so, can I suggest removing that text?  It means that I have to manually delete the contents of the search field if I want to do a search from my profile screen.  Thanks!


change the command+tab and command+` behavior in Mountain Lion

When it is a switch between applications, we use Command+Tab, and when it is a switch within an application, we use Command+`.  Can I just use Command+Tab for all cases, as in Windows?


Cannot parse bibliography items in biber

I am experiencing a rather weird issue. I am using some citations in a document and surprisingly some items are not parsed. My code is  \RequirePackage{filecontents} \begin{filecontents*}{cite.bib}  @article{Chiari,     author    = "M. Chiari, L. Giuntini, P.A. Mando, N. Taccetii",     title     = "Proton elastic scattering cross-section on boron from 0.5 to 3.3 MeV",     journal   = "Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms",     volume    = "184",     number    = "3",     pages     = "309-318",     year      = "2001",     month     = "November", hyphenation={english}  }  @article{Mayer, title = "The $^{11}B\left(p,\alpha_0\right)^8Be$ nuclear reaction and $^{11}B(p,p)^{11}B$ backscattering cross sections for analytical purposes ", journal = "Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms ", volume = "143", number = "3", pages = "244 - 252", year = "1998", note = "", issn = "0168-583X", doi = "http://dx.doi.org/10.1016/S0168-583X(98)00383-8", url = "http://www.sciencedirect.com/science/article/pii/S0168583X98003838", author = "M. Mayer and A. Annen and W. Jacob and S. Grigull", hyphenation={english} }  @article{Rihet, title = "States in $^{12}C$ from resonant proton scattering ", journal = "Journal de physique ", volume = "38", number = "1", pages = "17 - 19", year = "1977", % note = "", issn = "0168-583X", doi = "http://dx.doi.org/10.1051/jphys:0197700380101700", url = "http://jphys.journaldephysique.org/articles/jphys/abs/1977/01/jphys_1977__38_1_17_0/jphys_1977__38_1_17_0.html", author = "Y. Rihet, A. Genoux-Lubain, H. Beaumevieille, R. Seltz, C. Gerardin,  D. Magnac-Valette ", hyphenation={english}  }  \end{filecontents*}  \documentclass[11pt,a4paper]{book} \usepackage[english,greek]{babel} \usepackage[utf8]{inputenc} \usepackage{kerkis} \usepackage[bibencoding=auto,backend=biber,babel=other]{biblatex} \addbibresource{cite.bib} \renewbibmacro{in:}{} \newcommand{\eng}[1]{\latintext#1\greektext} \newcommand{\gre}[1]{\greektext#1\latintext}  \begin{document}  το ενεργειακό και γωνιακό εύρος(\cite[\eng{Chiari}]{Chiari}) καλύπτουν για την γωνία των $120^\circ$ τις ενέργειες $2250,2800\;keV$ για το $^{11}Β$ (\cite[\eng{Mashkarov}]{Mashkarov}, \cite[\eng{Dejneko}]{Dejneko}) και όλο το ενεργειακό εύρος  για το $^{10}Β$ (\cite[\eng{Overley}]{Overley}). στην ενέργεια των $3300keV$(\cite[\eng{Rihet}]{Rihet}). Τέλος, λόγ $2250\;keV$(\cite[\eng{Mayer}]{Mayer}). Η επιλογή των εν λ \cite[\eng{Mayer}]{Mayer} και \cite[\eng{Chiari}]{Chiari}, οι οποίες είναι πειραματικές, η απόδειξη της μη έντονης  γωνιακής εξάρτησης φαίνεται από τα δεδομένα του \cite[\eng{Chiari}]{Chiari}. \printbibliography \end{document}   and my output is    My compilation process is   pdflatex -shell-escape file.tex biber file pdflatex -shell-escape file.tex   Any idea on why is this happening and how can it be fixed?


Center of free group (of rank greater than 1) is trivial

I am currently reading through a solution of the following problem and I am having a bit of trouble. The problem is as follows:     Let $S$ be a set and $F$ be the free group on $S$. Show that if $|S| > 1$, then $Z(F)$ is trivial.    In order to deduce a contradiction, suppose that $w \in Z(F) \setminus \{e\}$ (where $e$ is the identity element). Let $w = a_{1}^{\pm1} \cdots a_{n}^{\pm 1}$ be the reduced word expression for $w$. Since $w \in Z(F)$, we have  $$ \left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right)w = w\left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right). $$ Now the left-hand side reduces to  $$ \left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right)w = \left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right)\left(a_{1}^{\pm1} \cdots a_{n}^{\pm 1} \right) = a_{n}^{ \pm 1}. $$ Comparing this to the right-hand side, we deduce that it must be the case that $a_{n}^{\pm 1}=a_{n-1}^{\pm 1} = \cdots = a_{1}^{\pm 1}$; so write $w = \left(a_{1}^{\pm 1}\right)^n$.    [Now every part of the proof makes sense to me thus far, but I do not see the rationale for the coming part.]     Since $|S| > 1$, let $b \in S$ be such that $a_{1}^{\pm 1} \neq b$. Then $wb = bw$ because $w \in Z(F)$, and so $\left( a_{1}^{\pm1} \right)^n b = b\left(a_{1}^{\pm 1} \right)^n$. However this implies that $a_{1}^{\pm 1} = b$, which is a contradiction.    I cannot see how to deduce that $a_{1}^{\pm 1} = b$ from $\left( a_{1}^{\pm1} \right)^n b = b\left(a_{1}^{\pm 1} \right)^n$. The solution says to consider the reduced words, but this does not seem to be very helpful considering $\left( a_{1}^{\pm1} \right)^n b$ and $b\left( a_{1}^{\pm1} \right)^n$ are already reduced.


Newbie here: Different results on PC and MAC. Why?

I am trying to learn the basics of C/C++ right now. I am going through a course on Lynda.com  My questions deals with a sequence of code from Chapter 4 "Macro caveats from the Course C/C++ Essential Training". I have followed all the setup procedures to get Xcode and Eclipse setup correctly on a Mac and Eclipse on a PC. When I run this code on a MAC and PC I get different results. Just trying to understand why that is happening and what I can do to get the same result on both.  Here is the code:  // working.c by Bill Weinman <http://bw.org/>  #include <stdio.h> #define MAX(a, b) ( (a) > (b) ? (a) : (b) )  int increment() {     static int i = 42;     i += 5;     printf("increment returns %d\n", i);     return i; }  int main( int argc, char ** argv ) {     int x = 50;     printf("max of %d and %d is %d\n", x, increment(), MAX(x, increment()));     printf("max of %d and %d is %d\n", x, increment(), MAX(x, increment()));     return 0; }   On a PC I get this result:  increment returns 47 increment returns 52 max of 50 and 52 is 50 increment returns 57 increment returns 62 increment returns 67 max of 50 and 67 is 62   On a MAC (both Xcode and Eclipse) I get this result:  increment returns 47 increment returns 52 increment returns 57 max of 50 and 47 is 57 increment returns 62 increment returns 67 increment returns 72 max of 50 and 62 is 72   Why is this happening and what can I do to make sure the results are the same?


This is NOT a duplicate. The other answers do not apply to this situation.   When trying to boot a 64 bit image in a headless VirtualBox, I get      This kernel requires an x86-64 CPU, but only detected an i686 CPU.   Unable to boot – please use a kernel appropriate for your CPU   My processor is 64 bit.  uname -a     Linux medusa 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux   It supports VMX  egrep '(vmx|svm)' /proc/cpuinfo  flags       : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat   pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc  arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx smx est  tm2 ssse3 cx16 xtpr pdcm lahf_lm dtherm tpr_shadow vnmi flexpriority   And the virtualization options are enabled in BIOS.  I've set the ostype to both Linux_64 and Ubuntu_64 but neither work. I've also tried setting VBoxManage modifyvm <vmname> --longmode on  "use a 32 bit image" isn't a solution, which is why I'm asking the question again. I see it's come up many times, and "your processor is 32 bit" is a very common response.  A potentially relevant piece of information is that the processor was upgraded after the initial installation of Ubuntu. I moved the processor that supports virtualization into this computer. I've had 64 bit VM's running on this machine before, with the same setup; I'm not sure if actually installing on the supported processor matters.


Is there any way that I can specify the order of gmail filters? A simple and concrete example: suppose that I have defined 3 gmail filters, F1, F2, F3.  But I did not define them all at the same time, say I did F1, F3 first.  Then I thought of F2 and defined it in gmail's Settings --> "Filters and Blocked Addresses".  gmail puts F2 at the end of my list so that it is F1, F3, F2.  Is there any way that I can make the gmail filter list have the order F1, F2, F3?  When I look at "Filters and Blocked Addresses", I do not see any kind of arrow or "move up" / "move down" functionality for the list. The reason why I want to specify the order of my filter list is that I have a fairly complicated filter hierarchy, and I am occasionally adding or removing filters from that hierarchy.  I would like my filter list to be in the same order as a depth first drill down of my label hierarchy. The only way that I currently know of to achieve my result is to remove all my filters and then add them back in the order that I want.  That is an awful solution.


Okay... So I've installed Ubuntu 14.04 (Upgraded from 12.04.3 ) I've been using Ubuntu for about two years now and I know myself around the system pretty well...   Every time I attempt to shut down the computer I always get stuck on the Ubuntu Splash menu and have to push the button to shut it off.  Specs:    6GB ram Intel Core 2 Duo CPU E7400 @ 2.80 GHz x2G  Graphics: Gallium 0.4 on AMD RV635 64bit OS Ubuntu 14.04 1TB hard drive (Dual booted Windows 7 on 600GB partition)


Is it right/possible to tag someone in comment while asking question

While asking any question, if I know some one knows the answer from the community, is it right to tag him in comment to get attention and increase probability of getting right answer quickly.  It might flood that user with lots of notification, but it seems to be a better way to get attention from someone appropriate quickly. Is it right/possible?   As I know there is bounty option available for getting attention on question, but that can be used after 2 days, so this might be a better option.


Python regex capturing before and after a pattern

I'm trying to get all the words before and after a given pattern in a sentence. Below is the code I'm using. Of course this is not perfect, so any suggestions are welcome.  My issue at hand is that, this is working for some patterns but not for others. For example, the given pattern below is not working, ie. re.match returns None.  sentence = "The agreements in this Section shall survive the resignation of the Administrative Agent, the L/C Issuer and the Swing Line Lender, the replacement of any Lender, the termination of the Aggregate Commitments and the repayment, satisfaction or discharge of all the other Obligations."  s = "commitments.*repayment" rex = "(?i)((?:\\S+\\s+){0,30})\\b" + s + "\\b\\W*((?:\\S+\\s+){0,30})" p = re.match(rex, sentence, re.IGNORECASE) print p   What am I doing wrong?


I am planning to buy a Mac Mini. I have a Windows laptop and wanted to get a Mac. But my job requires me to move every 3-4 months, so don't want to get a monitor that I will have to carry around all the time. My plan was to get the Mac Mini and use my Windows laptop as a monitor whenever I use the Mac Mini... But i am not sure if this is possible... Maybe some external card or something...? Please let me know if this is possible at all...?


Black Bodies, why is $\nu_{max}\neq {c}/\lambda_{max}$?

I am trying to find Wien's law from Planck's equation but instead of $\lambda$ I am finding frequency.   I found it:  $$\nu_{max} = \frac{(2.82)k_bT}{h}.$$  The following question asks: Why $\nu_{max}\neq {c}/\lambda_{max}$?  I cannot use $\nu = \frac{c}{\lambda}$ to turn Wien's law into frequency: $$\lambda_{max}=\frac{b}{T},$$ where $b$ is Wien's displacement constant.   EDIT   The question I am wondering about is b)


Is Ice Knife's explosion damage affected by rolling a critical?

One of the druids in my group have the spell Ice Knife which specifies:     Make a ranged spell attack against the target. On a hit, the target   takes 1d10 piercing damage. Hit or miss, the shard then explodes. The   target and each creature within 5 feet of the point where the ice   exploded must succeed on a Dexterity saving throw or take 2d6 cold   damage.     When making the first roll he rolled a natural 20. The piercing damage of the knife .   Does the explosion of the shard also benefit from the increased damage from the critical hit?  (4d6 rather than 2d6)


SE website not listed on my profile main page

My profile main page ():  My SE websites ()  "Software Recommendations" is missing on my profile main page. I think it's related to the repeatedly dismissed bug


Not able to Sort Url Column in LWC Datatable

i am trying to build datatable where I want to show Product Name as url so that User can go that particular record   JS where i am making my name field as URL    {         let nameUrl;      this.showSpinner = false;      this.allProducts = result.map(row =>{      nameUrl = `/${row.Id}`;      return {...row,nameUrl}   });   Now when I am trying to sort "nameUrl" in my datatable the sort direction stays "asc" and doesn't change to "desc" even after clicking multiple time. I am not able to understand why this is happening. When i am using the same sort function for any other field it works perfectly fine. Can anyone let me know where i am wrong and how i can rectify the same  JS file for my Data Table   export default class SearchProductDataTable extends LightningElement { @api products; @track sortBy; @track sortDirection; @track allProducts; @track prodNameObject = []; cols = columns;   handleSortdata(event){      let sortbyField= event.detail.fieldName;     if(sortbyField ==='nameUrl'){         this.sortBy = 'Name';      } else{         this.sortBy = sortbyField;      }     this.sortDirection = event.detail.sortDirection;     console.log('This is the sort direction ',this.sortDirection);     //Console Log : When nameUrl field is clicked Sort Direction is always 'asc'     this.sortData(this.sortBy, this.sortDirection); }  sortData(fieldName, sortDirection){     let data =  [...this.products];     console.log('This is the sort value of nameurl ',fieldName);     //function to return the value stored in the field     let key =(a) => a[fieldName];      //console.log('This is key value ',key);     let reverse = sortDirection === 'asc' ? 1: -1;     data.sort((a,b) => {         let valueA = key(a) ? key(a).toLowerCase() : '';         let valueB = key(b) ? key(b).toLowerCase() : '';         console.log('This is Value A',valueA);         console.log('This is Value B',valueB);         let vale = (valueA > valueB) - (valueB > valueA);         console.log('This is Vale ',vale);         console.log('This is the value of reverse',reverse);         return reverse * ((valueA > valueB) - (valueB > valueA));     });     this.products = data;  }  get showTable(){     if(this.products.length > 0){         return true;     } else {         return false;     }  }   Data Table Columns :  const columns = [ {     label:'Prd Record Link',     fieldName:'nameUrl',     type:'url',     typeAttributes: {label: { fieldName: 'Name' },                      target: '_blank'},     sortable: true,     wrapText: true }, {     label: 'Product Name',     fieldName:'Name',     type:'text',     sortable:true,     wrapText: true }, {     label: 'Product Code',     fieldName:'ProductCode',     type:'text',     sortable:true,     wrapText: true }, {     label:'Eng Status',     fieldName:'Eng_Status__c',     type:'text',     hideDefaultActions:true }, {     label:'Quotable',     fieldName:'Quotable__c',     type:'text',     hideDefaultActions:true }, {     label:'Quoting Rules',     fieldName:'Quoting_Rules__c',     type:'text',     hideDefaultActions:true }, {     label:'USD Price',     fieldName:'USD_Price__c',     type:'currency',     typeAttributes:{currencyCode: 'USD'},     hideDefaultActions:true }, {     label:'AUD Price',     fieldName:'AUD_Price__c',     type:'currency',     typeAttributes:{currencyCode: 'AUD'},     hideDefaultActions:true }, {     label:'CAD Price',     fieldName:'CAD_Price__c',     type:'currency',     typeAttributes:{currencyCode: 'CAD'},     hideDefaultActions:true }, {     label:'China Price',     fieldName:'China_Price__c',     type:'currency',     typeAttributes:{currencyCode: 'CNY'},     hideDefaultActions:true }, {     label:'EUR Price',     fieldName:'EUR_Price__c',     type:'currency',     typeAttributes:{currencyCode: 'EUR'},     hideDefaultActions:true }, {     label:'GBP Price',     fieldName:'GBP_Price__c',     type:'currency',     typeAttributes:{currencyCode: 'GBP'},     hideDefaultActions:true }];


Programmatically render user edit form with form mode

I can't figure out to render the user profile form with a custom display mode. I did search the forum and internet and it seems that this piece of code should work:    function mymodule_entity_type_build(array &$entity_types) {       $entity_types['user']->setFormClass('my_custom_form_display_mode_id', 'Drupal\user\ProfileForm'); }   combined with  $user = \Drupal::entityTypeManager() ->getStorage('user') ->load(1);  $formObject = \Drupal::entityTypeManager()   ->getFormObject('user', 'my_custom_form_display_mode_id')   ->setEntity($user); $form = \Drupal::formBuilder()->getForm($formObject);   However, the form that gets loaded actually contains all fields and is not even using the default form mode. What am i doing wrong?


As a comment in  user  wrote:     Another reason to avoid | true is that if the command produced enough output to fill up the pipe buffer, it would block waiting for true to read it.   Do we have some way of finding out what the size of the pipe buffer is?


I have the following setup  Object : CurrencyConversion__c  Field  : Input_Currency__c  Field  : Convert_Currency__c  I want to invoke a callout to an external webservice via a trigger (before inserting a record) in the above custom object.  I will pass "Input_Currency__c" as parameter (Id will not be passed) and the HTTP Response will contain value for "Convert_Currency__c" which I will stamp it back.  Since this webservice will be asynchronous how am I to identify the same record for which this callout was made by the time I get the response from the webservice ?


Convert string with encoded UTF8 symbol into cyrillic symbol c#

From request  I receive an answer like this:      "\"1   \u0410\u0441\u043a\u043e\u043b\u044c\u0434\u0456\u0432\u0441\u044c\u043a\u0438\u0439".   For request I'm using:  HttpWebRequest request = (HttpWebRequest)WebRequest.Create(FullRequestString);     request.Method = "GET";   I receive response by the construction:  HttpWebResponse response = (HttpWebResponse)request.GetResponse(); using (Stream stream = response.GetResponseStream())  {   using (StreamReader reader = new StreamReader(stream))    {    string line = "";    while ((line = reader.ReadLine()) != null)     {   How can I transform the character like \u043b into cyrillic symbol


Why can we apply the $E=hf$ equation for electrons?

So in my textbook, it states that the $E=hf$ equation applies to electrons, and all particles, not just photons.   But in order to prove this, wouldn't these particles need to have zero mass, to satisfy $E=pc$ from Einstein's equation?  In Einstein's theory of relativity $E^2= p^2c^2 + m^2c^4$, we get $E=pc$ because we consider the mass to be zero.   For $E=hf$ to work for other particles, don't we need to assume electrons have zero rest mass?


Is it possible to download using the Windows command line?

Without using any non-standard (Windows included) utilities, is it possible to download using the Windows command line?  The preferred version is Windows XP, but it's also interesting to know for newer versions.  To further clarify my question:   It has to be using HTTP The file needs to be saved Standard clean Windows install, no extra tools   So basically, since everybody is screaming , I want simple Wget functionality, without using Wget.


What is the difference between MapBox and CartoDB ?


Let $n$ be a integer not equal to zero, $p$ a prime and $$|n|_p = p^{-\operatorname{ord}_p(n)}; |0|_p=0$$  Proposition: $|xy|_p=|x|_p|y|_p$  We want to show: $\operatorname{ord}_p(ab)=\operatorname{ord}_{p}(a)+\operatorname{ord}_p(b)$ So if we suppose there is a largest integral $v$ such that $p^{v}|(ab)$, then we can split up v such that $p^{v_1}|a,p^{v_2}|b$. If we suppose that there exist $v_1,v_2$ with them both being the largest integers such that $p^{v_1}|a, p^{v_2}|b$,  with $v_1+v_2= : v $ then $p^v|ab$. (I don't believe this to be a formal proof but rather my best own "idea" I can come up with...)  The script also mentions that the padic valuations' sums are bounded: $|x+y|_p\le \sup\{|x|_p,|y|_p\}$, how to show this?   Edit:   According to Robert Israel and Bill Dubuques answers, the first proposition is proven, if I understood correctly:   Given $ord(a)= v$ and $ord(b) = u$ which is the same as $a:= p^{v}m, b:= p^{u}n$ with $gcd(m,p)=gcd(n,p)=1$, because $ab=p^{u+v}mn$ with $gcd(mn,p)=1$ it follows that $ord(ab)=ord(a)+ord(b)$ and so $|xy|_{p}=p^{-ord(xy)}=p^{-(ord(x)+ord(y))}=|x|_{p}|y|_{p}$  Now to show: $|x+y|_{p}\le sup\{|x|_{p},|y|_{p} \}$  and the second can be tackled like this: set $a:=p^{v}m. b:=p^{u}n$, then checking two cases $1:(u=v)$ and $2:(v<u)$: $(a+b)=p^{v}m+p^{u}n= p^{v}(m+p^{u-v}n)$ so in case of (u=v) it follows that  $ord(a+b)= u = sup\{ord(a),ord(b)\}$  and in case of $(v<u)$ because the biggest v is $v:= u-1$: $ord(a+b)\le p^{u-1}(m+pn) \le p^{u}(m+n)= sup\{ord(a),ord(b)\}$  It seems that I did something wrong in both cases...


How to write "\" the set difference symbol without LaTeX getting confused?

I am trying to use the "\" symbol in my text for set difference but LaTeX gets confused and will not read it. How can I make it work?


Maximum number of points in a skill per level?

I remember when creating my level 1 rogue many moons ago - for my first Pathfinder game ever - that our GM told us there was a max. number of skill points we could put into each skill.   I don't remember the reason for this, what the limit was or whether any of our group had seen this in the rules. I've not been able to find anything so far. Is anyone able to fill me in?


Why isn't this awk command doing a full outer join?

Objective: Merge the contents of two files using common key present in the files   file1.txt  =========  key1   11  key2   12  key3   13    file2.txt  =========  key2   22  key3   23  key4   24  key5   25    Expected Output :  ==================  key1   11  key2   12    22  key3   13    23   key4   24  key5   25   Approaches tried:   join command:  join -a 1 -a 2 file1.txt file2.txt ## full outer join  awk:  awk 'FNR==NR{a[$1]=$2;next;}{ print $0, a[$1]}' 2.txt 1.txt    Approach 2 is resulting in a right outer join and NOT a full outer join:     key1  11    key2  12    22    key3  13    23    What needs to be modified in approach 2 to result in a full outer join?


Awaiting AE recommendation - Can be rejected?

I already referred to this , ,  I recently submitted my paper to a journal 40-45 days back. For the first 10 days, it was reviewed by the managing editor and sent to us for some format issues, etc. Later, it has been under "Awaiting review scores" for the past 25 days. And from the past few days, I see it as "Awaiting AE recommendation". I know the next stage is to Editor In chief. But my question is as below a) Is it possible to be rejected at this point? Because we didn't receive any email till now on clarifications, request to revise something, etc. Could it mean direct rejection? Like reviewers gave low scores and it is bound for rejection? b) For ex: Let's say the paper requires some revision based on reviewers. In that case, will it be communicated directly to us (by the managing editor) or even request for revisions/clarifications will also happen through "AE" and "EIC" c) Am I right to understand that based on the info that I shared, there are only two possible outcomes. Either outright reject or acceptance notification is the next possible step? No revisions because it is already "Awaiting AE recommendation"


How to add dictionary key-values to an object as properties

This question has already been asked, but not exactly like this (I can't use any of the answers): I want to call a function that returns a dictionary, and if this dictionary is not None, loop on it and use its key + values on an object. NB: this object is from a class and its class can't be modified. Something like: def check_ok(s):   return {'prop_1': 'x',           'prop_2': 'y'}   def check_and_update(obj, st):     result = check_ok(st)     if result is not None:         for k, v in result.items():             obj.k = v  # doesn't work, of course  What is the solution?


How do I programmatically place a block?

From UI you can add a block in a region in that way:     Go to Admin -> Structure -> Block layout (/admin/structure/block).   Click on "Place block" button besides the region name.     I want to do the same thing but programmatically. How do I add an existing block to a region and save it? This block should then be displayed in that region and be  available in the Block layout page.


My hard disk has been formatted accidently

I chose the second option for installing Ubuntu because I thought it would only remove Windows (8.1). However, now I have an empty hard drive.  I had very important files on my hard drive. What should I do? My future as a vet has been formatted!


Set a environmental variable that includes a dash

I've read through multiple postings and can't seem to export a variable with a special character in Centos 7.5 (I believe the special character is the problem, please correct me if it's something else).  The command  export TEST-ME=blah returns -bash: export: TEST-ME=blah: not a valid identifier.  I've tried escaping with a backslash and multiple variants of single and double-quotes with the same result.  What am I doing wrong?


How do I copy files using Windows Batch?

I have a directory with several subdirectories with files. How can I copy all files in the subdirectories to a new location?  Edit: I do not want to copy the directories, just the files...  As this is still on XP, I chose the below solution:   for /D %S IN ("src\*.*") DO  @COPY "%S\" "dest\"   Thanks!


Let me start with a simpler version of my actual problem. Say I have a partition $\mathbb{N} = \cup_k I_k$ where the $I_k$ are disjoint, and an absolutely convergent series $\sum_n x_n$ in $\mathbb{R}^d$. I want to show the identity $\sum_n x_n = \sum_k \sum_{i\in I_k} x_i$. In this simple situation I can show this using Fubini's theorem, but actually I'm interested in the situation of Banach space valued series that converge unconditionally, so I'd appreciate a more elementary approach that is better suited for generalization.


Error In Displaying Message When There Is An Attachment

I am trying to display an error message in SharePoint 2013. I added the following code inside my ItemAdding() event receiver to force it to have error:  properties.Status = SPEventReceiverStatus.CancelWithError; properties.ErrorMessage = "test";   It works okay, I can see the error message.  However, when I attach any files, and try again, after saving, the attachment will disappear. When I attach again, I will get a server error:   Please advise.


How to convert color code into media.brush?

I have a rectangle that i want to fill with a color. When i write Fill = "#FFFFFF90" it shows me an error:     Cannot implicitly convert type 'string' to 'System.Windows.Media.Brush   Please give me some advice.


How can I simply and sustainably remove Chess from my macBook Air, Mojave?

I have a list of applications I was interested in possibly removing as long as the OS does not need them to function.  For starters I want to remove Chess and Stocks as I never use them.  However when I right click on them on Finder, there is not option to delete.  I can't imaging that Chess is integral to the OS working so how can I delete it?  I need it deleted it in such a way that when my computer automatically updates it does not show up again.  Thanks.


Realtion of acceleration and deformation

What will happen if I apply 10N force to a body's one end and 11N to it's others end? Which force will accelerate it, which force will deform it? Why?


Possible Duplicate:          I have two antivirus programs installed (Avira and Avast), and it is really impacting performance. I tried uninstalling them using the Add/Remove Programs control panel applet, but I get an error massage.  I checked Program Files and some of the files seem to be missing (which may explain why they did not work correctly anyway).  Is there a way to solve this problem?


Where can I get the repositories for old Ubuntu versions?

Where can I get the old repositories for Ubuntu versions? In my case, it's 9.04 Jaunty?   I found all the official repositories and their mirrors have been removed. I am wondering where I can get the repository list for this version?


How can I see all the members of a group in Linux?


How can I read my hard drive’s SMART status in Windows 7?

How can I read the  S.M.A.R.T. state of my HDDs while using Windows 7, either automatically or manually?


I am inserting into two tables at the same time, tss_client and tss_details. First, I insert into tss_details, then using Details_ID from there, I insert into tss_client.   How to I get the most recent ID, from tss_details? I'm trying LAST_INSERT_ID() but it doest work   addDetailsQry.prepare("INSERT INTO tss_details(Username, Password, Email, Description, etc..) "                       "VALUES (:Username, :Password, :Email, :Description, etc..");   addClientQry.prepare("INSERT INTO tss_client(Client_Name, Website, Contact_Details_ID)"                      "VALUES (:Client_Name, :Website, :LAST_INSERT_ID()");  addDetailsQry.bindValue(":Username", username); addDetailsQry.bindValue(":Password", password); addDetailsQry.bindValue(":Email", email); addDetailsQry.bindValue(":Description", description);  addClientQry.bindValue(":Client_Name", clientName); addClientQry.bindValue(":VAT_Number", VATNumber); addClientQry.bindValue(":Website", website); addClientQry.bindValue(":Contact_Details_ID", /*what would i put here*/ );  if(addDetailsQry.exec()) {     qDebug() << "Client Details added!";      if(addClientQry.exec())     {         qDebug() << "Client added!";     } }   The ID column in tss_details is an identity.   I'm using ODBC and SQL Server version:     'Microsoft SQL Server 2016 (RTM) - 13.0.1601.5 (X64)   Apr 29 2016 23:23:58   Copyright (c) Microsoft Corporation  Express Edition (64-bit) on Windows 10 Pro 6.3  (Build 14393: )   and  I get:     [Microsoft][ODBC SQL Server Driver][SQL Server]'LAST_INSERT_ID' is not a recognized built-in function name.


Oneboxing a Stack Exchange post using HTTPS does not work

When you post a link from Stack Exchange into the chatbox using HTTPS, the link does not onebox. However, if you change the link to HTTP, it works. See the screenshot below:    HTTPS URLs should onebox, too.


Ubuntu 17.10 (x11).    Is it possible for an administrative user to have a password for the login screen that is different from the password for elevated permissions?  If so, how do I change the login password for just the login screen?


How to install Gnomeradio in Ubuntu 16.04?  Thanks.


Exercise 1.10 from Silverman "The Arithmetic of Elliptic Curves "

I am having trouble with Silverman's exercise 1.10(b). The converse of (a) is easy because there is no integer solution to the equation when $p \equiv 3$ mod $4$. However, this method does not work for (b) because we always get empty set when intersecting whatever $V_p (p \equiv 3 $ mod $4)$ with $\mathbb{Q}$. I tried to intersect two varieties $V_p, V_q$ with something else, for example $\mathbb{Q}({\sqrt{p}})$ and try to tell the difference, but this is hard since it is very possible for $V_q$ to have nonempty intersection with $\mathbb{Q}({\sqrt{p}})$ and I think it is true that if so then $V_p, V_q$ are isomorphic over $\mathbb{Q}({\sqrt{p}})$. Are there some invariants I can use in this circumstance to show that two varieties are not isomorphic over $\mathbb{Q}$?


My computer A has two networks, one connects to internet. The other one connects to computer B. How can I setup A to route all the internet traffic from B through a proxy running on A without setting B too much, possibly acting like a transparent proxy?


Where can I ask this question about a life choice?

I've tried the Chemistry Exchange and they suggested the academia exchange and the academia exchange suggested asking meta and in both of those exchanges I was told my question was off topic. My question is a life choice about two different awards and which one to take. Where on StackExchange can I ask it?  The Description:  As part of my Chemistry A Level Techniquest has given me the opportunity to do 70 hours of a task with a group and if done correctly I could gain a Gold CREST award which can be put on my CV for Uni.  As part of my gold CREST award I must do talks to High Schools and primary school children on why Chemistry is fun but also important to everyday life. I thought this could be really enjoyable but....  I am also doing a Silver Duke of Edinburgh at the same time. I want to take Science related courses in University and revising for A Levels at the same time as doing a GOLD CREST award and Duke of Edinburgh seems really difficult.  I was thinking I should drop one but which one should I drop?  Is it even possible to do revision, and both challenges at the same time?  Which is better to put on a CV?  What option gives me more life skills?


Can you get duplicate items out of Loot Box?

I've never gotten a duplicate item out of a Loot Box, but I'm wondering if it's even possible.  Does it automatically turn into gold depending on the rarity of the item?  How does the game handle duplicate items?


iPhone not charging in Windows. Driver without iTunes?

On a Windows 8 machine, I've connected an iPhone 4s. Windows makes a audible chime for 'device connected', but doesn't allow charging in any USB port.  iTunes isn't installed, and cannot be installed at this time under corporate policy.  The iPhone shows as a generic device / toaster under Control Panel's Devices as below. The iPhone does NOT show as charging.  Is there a driver to install to ensure the iPhone is detected and can charge via USB without installing iTunes?  I've tried:   forcing Windows Update


First-year matrix problem: How do you show that a sum of an identity matrix and another matrix is equal to the sum's inverse?

The following is the problem at hand:  $A^4 = 2A^2.$ Prove that $(I-A^2) = (I-A^2)^{-1}$  My attempts at a solution:  $I = A^{-1} * A,$ therefore we can start with $(A^{-1}A - A^2) = (A^{-1}A - (1/2)A^4) = (A^{-1}A - A^2) = (A^{-1}A - (1/2)(A^{-4})^{-1}) = ???$  I'm having problems with the fundamentals of this question. Sure, I can play around with the individual matrices on the left side, but that doesn't help to handle the inverse of a sum of matrices, like how the transpose of a sum is equal to the sum of the transpose of its individual matrix terms. How do you approach this without delving into more complex matrix operations?


Given a Debian-based OS, If the OS image becomes corrupted, how can it reinstall over the network remotely

We have a raspberry pi system that needs to be able to remotely re-image itself, if the image becomes corrupted or on demand. How do I go about doing this?  Also, how do I setup a pi that wasn't originally configured to do this?  The OS I am using is Raspbin, also device is 4 hours drive away. So physically changing the SD card is a no go.


Motivation behind the definition of tangent vectors

I've been reading the book Gauge, Fields, Knots and Gravity by Baez.  A tangent vector at $p \in M$ is defined as function $V$ from $C^{\infty}(M) $ to $\mathbb R$ satisfying the following properties:   $V(f+g)=V(f) + V(g)$. $V(\alpha f)= \alpha V(F)$. $V(fg) = V(f)g(p) + V(g)f(p)$.   Can someone explain me what is the physical interpretation of tangent vectors and the above definition?


Which is more preferable to write $\log(x)$ or $\ln(x)$

Which one is more preferable to write when you are writing an exam. Is it $\log(x)$ which denotes the natural logarithm or is it $\ln(x).$


Simplify the subtraction of two summations.

$$\sum_{i=1}^n (3i^2 +4) - \sum_{j=2}^{n+1} (3j^2 +1) $$  I thought I would use the distributive rule but the question stipulates that my answer should not include a summation sign...


Difficulty computing a tricky integral (computing the expected value of $e^X$ where $X$ is standard normal)

I suspect that this exact integral has been asked about before, but finding it among the sea of questions title "difficult integral" is daunting. I am trying to compute  $$\frac{1}{\sqrt{2\pi}}\int_{-\infty}^{\infty}e^{-\frac{x^{2}}{2}+x}dx$$  This integral showed up when I found myself needing to compute the expected value of $e^{X}$ where $X$ is a standard normal random variable. Wolfram says that the integral evaluates to $\sqrt{e}$, but I haven't been able to get it to work out. Any help would be appreciated.


Aligning equality signs while using stack relations

I am working with an align environment and would like to add some hints at the equality signs by specifying the used equation number at some steps. However, if I do that the equality signs don't align anymore. Is there a way to get the equality signs to align instead of the whole stack relation? See below for a minimal example. \documentclass{book}  \usepackage{amsmath}  \begin{document}  \chapter{Test align equality}    \begin{equation}\label{eq::ac}     a=c   \end{equation}    \begin{align*}     a &= b \\     &\stackrel{(\ref{eq::ac})}{=} c   \end{align*} \end{document}


What is the definition of a symmetric distribution?

What's the definition of a symmetric distribution? Someone told me that a random variable $X$ came from a symmetric distribution if and only if $X$ and $-X$ has the same distribution. But I think this definition is partly true. Because I can present a counterexample $X\sim N(\mu,\sigma^{2})$ and $\mu\neq0$.  Obviously, it has a symmetric distribution, but $X$ and $-X$ have different distribution! Am I right? Do you guys ever think about this question? What's the exact definition of symmetric distribution?


I wonder how to log GPU load. I use Nvidia graphic cards with CUDA.  Not a duplicate: I want to log.


'tasksel install lamp-server' verses 'apt-get install lamp-server^'

Is there a reason why 'tasksel install lamp-server' or 'apt-get install lamp-server^' is better than another when setting up a fresh lamp server (or other group install)? Are they really any different or does one simply map to the other somehow?   is about practice related to installing a lamp server, this question is about philosophy behind the two methods of installing a task. lamp-server is simply used as an example. I know how to accomplish what I want to accomplish. What I'd like to know more about is why there are two methods and which method is preferred in which circumstance. The other comes across more broad than I intend this to be.


Font of the Stack Exchange for Android app is too small

I use a Nexus7 2. When I use Stack Exchange on it, the font inside the app is too small. It's too hard to read. How can I make it larger?


redirect rule for http://www.example.com/http://www.example.com

Checking web master tools I've found a third party has incorrectly linked to my site with a url following this pattern:    I added in a rule to my htaccess file, however I get a 403 forbidden response.  RewriteRule ^http://www.example.com / [r=301,l,nc]   How should I go about resolving this rule?  Thanks


Why Can't I Flag from the Low Quality Review Queue?

I just spotted a spam answer in the VLQ review queue on Travel. I wanted to flag but there was no link. So I clicked Delete and then used the history to get to the question and flagged it as spam. But why wasn't that an option in the Review?


Gravity in an Earth-sized hole in "solid" outer space

I'm a math PhD student, and far from an expert on physics. If anything is ambiguous or uses the wrong terminology, please correct it or let me know.  About a decade ago, a friend gave me a paradoxical thought experiment that I still haven't been able to resolve, although I've asked around here and there:     Suppose that earth and outer space were "flipped" in such a way that the vacuum of space became an earth-like solid and earth became an earth-sized hole in this solid: a "Swiss cheese universe". How much gravity would a person experience if they were standing inside of the earth-sized hole with their feet on the boundary?   I have two mutually exclusive answers which are equally convincing to me. I'm interested to hear an explanation of which answer (if any!) is correct, and where the reasoning breaks down in the wrong answer.  Answer #1: The person experiences earth-like gravity.  This answer argues that for almost every particle in the universe (shown below in blue and red) there is a particle in the "opposite" position which creates an equal and opposite pull. Except for that the particles in an earth-sized sphere right underneath the person (shown in yellow) don't have "opposite" particles, so the net force the person experiences is due to the particles in the earth-sized sphere underneath them.    Answer #2: The person experiences no gravity.  Due to the , if the person is inside of a hollow sphere of any mass and thickness, they experience no force due to gravity. In particular, in the limit, as the thickness goes to infinity, the force due to gravity remains zero.


How can I transform a date to string when the date is retrieved from a SQL?

I am trying to show the DATE in a word document. However, the code broke with the following exception. (I believe I need to change the DATE to STRING       d.add_run(date_implemented(Part_No_New_Part))   File "C:\Program Files (x86)\Python37-32\lib\site-packages\python_docx-0.8.7-py3.7.egg\docx\text\paragraph.py", line 37, in add_run     run.text = text   File "C:\Program Files (x86)\Python37-32\lib\site-packages\python_docx-0.8.7-py3.7.egg\docx\text\run.py", line 163, in text     self._r.text = text   File "C:\Program Files (x86)\Python37-32\lib\site-packages\python_docx-0.8.7-py3.7.egg\docx\oxml\text\run.py", line 104, in text     _RunContentAppender.append_to_run_from_text(self, text)   File "C:\Program Files (x86)\Python37-32\lib\site-packages\python_docx-0.8.7-py3.7.egg\docx\oxml\text\run.py", line 134, in append_to_run_from_text     appender.add_text(text)   File "C:\Program Files (x86)\Python37-32\lib\site-packages\python_docx-0.8.7-py3.7.egg\docx\oxml\text\run.py", line 142, in add_text     self.add_char(char)   File "C:\Program Files (x86)\Python37-32\lib\site-packages\python_docx-0.8.7-py3.7.egg\docx\oxml\text\run.py", line 156, in add_char     elif char in '\r\n': TypeError: 'in <string>' requires string as left operand, not datetime.datetime   Repl Closed  I am able to generate the document. However, this is my Output  Date implemented: (datetime.datetime(2011, 5, 31, 0, 0),)  I want my output to be like this:  Date Implemented: 5/31/2015    The functions are the following:  def date_implemented(Part_No_New_Part):     dsn_tns = cx_Oracle.makedsn('Server_NAME', 'XXXXX', service_name='TEST')     conn = cx_Oracle.connect(user=r'XXX', password='XXXX', dsn=dsn_tns)     c = conn.cursor()     w_sql =('SELECT RELEASED_DT FROM TABLE1         WHERE PART_NO = UPPER(TRIM(:Part_No_New_Part)) AND STATE =\'Released\'')     c.execute(w_sql,[Part_No_New_Part])     for result in c:         if result ==' ':             print(" ")         else:             print('')     return result   def document(result):         d = doc.add_paragraph()     d.add_run('Date implemented: ').bold=True     d.add_run(date_implemented(Part_No_New_Part))


nextLine() in java cannot get the exactly value I want

public static void main(String args[]){     System.out.print("Type new, wil display TRUE:");     Scanner sc = new Scanner(System.in);     String userInput = sc.nextLine();      if(userInput=="new"){         System.out.println("TRUE");     }else {         System.out.println("FALSE");     } }   I have no idea why new not equals to new.   Please give me some hints :)


Complex Integration doubt in the solution

I'm trying to find the value of $$\int_0^\infty e^{-ax}\cos(bx)\,dx,\quad a>0.$$  by integrating $e^{−Az} ,A=\sqrt{a^2+b^2}$, over an appropriate sector with angle $ω$, with $cos ω=\dfrac{a}{A}$.  I'm seeing some solutions and I have the following questions:  1) It seems $ω= cos^{−1}(a/A)$ is strictly between 0 and $\pi/2$?  2) Why is it true that $\cos(\theta) \geq 1 - \dfrac{2\theta}{\pi} $?  how to prove?  Can someone answer both questions with details?


How do I specify in Javascript regex for beginning sequence of characters and ending sequence of characters

I have a string representing HTML, and I am trying to use str.replace(regex, "") to replace all instances of regex in a string with an empty string.  The substring that I need to replace begins with <!--[if and ends with <![endif]-->, and there are multiple occurrences in the string. Here is the regex that I tried: const regex = /^(<!--\[if).*(<!\[endif]-->)$/g  To me, this says "a string that begins with <!--[if and ends with <![endif]--> and has any number of characters in between, while escaping the opening square brackets and using the global flag."  That's what I want, so I can use str.replace: const newString = oldString.replace(regex, "")  I'm not catching any matches.  I can only think that I'm missing something about the grouping of the sequence of characters at the beginning and end.


I was using blender and I created a little character and when it came to putting it in pose mode so I could begin to animate it, from then on the navigation around the 3D window will not work it will zoom in and out but the only way for me to navigate now is through the View menu and this obviously takes forever and I can't get the angles I want, could I have pressed something to make it this way? I just generally cannot navigate at all around my interface.


I have some problems understanding  of this problem:  Given $f,g : \mathbb{R} \rightarrow \mathbb{R}$ - continuous functions with period $1$, prove that  $$\lim _{n \rightarrow \infty} \int_0^1 f(x)g(nx) \, dx = \int_0^1 f(x) \, dx \cdot \int_0^1g(x) \, dx$$  It says there that if we split this integral into $n$ parts to get  $$\int_0^1 f(x)g(nx) \, dx = \sum_{r=0}^{n-1} \int_{\frac{r}{n}}^{\frac{r+1}{n}} f(x)g(nx) \, dx$$  we will have   $$\int_0^1 f(x)g(nx) \, dx = \sum_{r=0}^{n-1} f\left(\frac{r}{n}\right) \int_{\frac{r}{n}}^{\frac{r+1}{n}}g(nx) \, dx$$  because for large $n$, $f$ is roughly constant over the range.  Could you tell me why $f$ is roughly constant over the range for $n$ large enough?  I would really appreciate all your insight.


Nodejs closures and res object in a callback function

I want to import some data from a json file (which contains a json array of objects) into mongodb using mongoose. When the route '/import' is called I load the file via "require" and start iterating.  router.get('/import', function (req, res) {   var data = require('../import/1.json');   nTotal = data.length;   for (var i = 0; i < nAppCount; i++) {     var obj = new MyObject(data[i]);     obj.save(check);   } });   Since JSHint warns me not to "make functions inside a loop", I created my function called check as follows:  function check (err,doc){   nProcessed++;   if (err) {     logger.log('error', err.message, err.errors);   } else {     logger.log('debug', "%d of %d processed",nProcessed, nTotal);     if (nProcessed===nTotal) {       res.render('index');     }   } }   Everything works as expected until the end but when all objects are processed I get:     ReferenceError: res is not defined   Isn't "check" supposed to "know" res variable being a closure function? How am I going to access "res"?  Note: I can make it work if I ignore jsHint warning.


Is it safe to drive in the Baltic countries during winter?

I am planning to drive from Kaunas to Riga between Christmas and New Years Eve. I would like to know how the road conditions usually are in this time of the year? Especially on the smaller roads. And is there anything special to consider when driving this route?


Omitting all xsi and xsd namespaces when serializing an object in .NET?

The code looks like this:   StringBuilder builder = new StringBuilder(); XmlWriterSettings settings = new XmlWriterSettings(); settings.OmitXmlDeclaration = true; using (XmlWriter xmlWriter = XmlWriter.Create(builder, settings)) {     XmlSerializer s = new XmlSerializer(objectToSerialize.GetType());     s.Serialize(xmlWriter, objectToSerialize); }   The resulting serialized document includes namespaces, like so:   <message xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"      xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"      xmlns="urn:something">  ... </message>   To remove the xsi and xsd namespaces, I can follow the answer from .  I want my message tag as <message> (without any namespace attributes).  How can I do this?


Does "it is entirely possible that" require the subjunctive form of the verb following "that"?

For instance, take the following sentence (from a real email exchange):  it is entirely possible that one WebEx is not enough   Is it correct? Should it be  it is entirely possible that one WebEx be not enough   ?  My reasoning is as follows:  (1) it is necessary that you be here --> (2) it is necessary that one WebEx be here -->  (3) it is necessary that one WebEx be enough -->  (4) it is necessary that one WebEx be not enough -->  (5) it is entirely possible that one WebEx be not enough -->    Is it true that the grammatical context is preserved throughout the entire transformation, starting with a sentence known to require the subjunctive (1) and ending with my example (5) ?  I have performed a few simple Google searches and the results are quite confusing:   "it is necessary that he be" yields 170,000 results "it is necessary that he is" yields 342,000 results "it is possible that he be" yields 985,000 results "it is possible that he is" yields 4,040,000 results   Of course, no conclusions can be drawn from these results ...


I took a look at the special situation that $f=1$, $${\lim_{h \to 0^+}}{\int_{-1}^1 \frac{h}{h^2+x^2}f(x)\,dx} ={\lim_{h \to 0^+}}{\int_{-1}^1 \frac{h}{h^2+x^2}\,dx} = \left.{\lim_{h \to 0^+}} \arctan{\frac{x}{h}} \right|_{-1}^1 = \pi $$  but I don't know how to find the next step.


Can multiple spells be activated with the same mana?

So first off I am fairly new to MTG and I was playing with my friend today and he corrected me on my move making. The way I thought it worked is that, for example, if I have a creature that requires 1 Mountain to attack it can attack after I tap the Mountain and the creature. However my friend said that the same land can be used multiple times in a turn, so I could use 2 other creatures on the battlefield that only required 1 Mountain to attack. Is this correct?


I can't install anything on Ubuntu 14.04 , kept saying "HASHSUM MISMATCH"?

Today I installed Ubuntu 14.04 . After that I tried to install Skype . But it gave the following error  E: Failed to fetch ht tp://security.ubuntu.com/ubuntu/pool/main/g/gcc-4.8/libgcc-4.8-dev_4.8.4-2ubuntu1~14.04.3_amd64.deb  Hash Sum mismatch E: Failed to fetch ht tp://security.ubuntu.com/ubuntu/pool/main/g/gcc-4.8/gcc-4.8_4.8.4-2ubuntu1~14.04.3_amd64.deb  Hash Sum mismatch E: Failed to fetch ht tp://security.ubuntu.com/ubuntu/pool/main/q/qt4-x11/libqtcore4_4.8.5+git192-g085f851+dfsg-2ubuntu4.1_i386.deb  Hash Sum mismatch E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?   Even when i tried to execute sudo apt-get -f install it also gave me the error . What is the problem ? I tried all the possible solutions out there in the internet , but none of them worked . Did anyone face this kind of problem ? I even tried apt get-update . But even after updating it didn't work .


How to add the only user on a Debian system back into the sudo group?

I'm using Debian on a headless server that I'm connecting to via ssh.  When I installed Debian, I did not create a root account, so the first user created was in the sudo group. Then I added that user to another group, but in my ignorance I used:  sudo usermod -G NewGroup UserName   instead of:  sudo usermod -aG NewGroup UserName   Without the 'a' (append), this removed the user from every group (including sudo) other than the default UserName group.  I've learned my lesson now, but is there any way to regain superuser access to this installation?  This is a test environment with nothing to backup or recover, so I can simply reformat if all is lost, but I thought I'd ask anyway.


how i show not related column in group by function at oracle

I just wanna display the name of who gain max salary at the department select first_name from(select max(e.salary),e.department_id from employees e group by e.department_id)


why are odd versions of Ubuntu rarely used?

I can see among my friends that Ubuntu versions which were released in odd year (2019, 2017, 2015, 2013) were rarely used. In the past, I could see that people were using it evenly (11.04 and before), but since 2014 with 14.04 LTS, no one used 15.04 and 17.04. They are also using 18.04 now even when it is the end of 2019 (19.10 released). Or is it just me, my friends and my colleagues?


Function always continuous in a Sobolev Space?

Hy everybody got a quick question. I know that all function F in a Sobolev Space has a continuous representative called U such as U=F almost everywhere.  Lets take for example: The Sobolev space on ]-1,1[    the function F(x)=0 on x<0 and F(x)=1 x>0  we can't find a continuous representative because it would be on a larger interval let say ]-eps ,eps[ so not in a Sobolev space the function F(x)=x on x<0 and x>0 and F(0)=1 where we could find the representative U=x   My question is: if F isn't continuous is it sure that it isn't an element of a Sobolev Space? It was given was given as a necessary condition in my course.  Thanks for the help.


Is it possible to dynamically create and modify images on a per pixel level in JavaScript (on client side)? Or has this to be done with server based languaged, such as PHP?   My use case is as follows:   The user opens webpage and loads locally stored image A preview of the image is displayed The user can modify the image with a set of sliders (pixel level operations) In the end he can download the image to his local HDD   When searching in the web I just found posts about using IE's filtering method, but didn't find anything about image editing functions in JavaScript.


Why do we seek to preserve gauge symmetries after quantization?

Gauge symmetries do not give rise to conservation laws via Noether's theorem, and they represent redundancies in our description of the system. So why do we want to keep them after quantization? For example:     But gauge symmetries are not symmetries at all. They are redundancies in our   description of the system. As such, we can't afford to lose them and it is imperative that they don't suffer an anomaly in the quantum theory.   (From , Chapter 5, Page 108).  If they are redundancies, then why do we want to formulate a theory with them in it? They give rise to all sorts of inconveniences, e.g. having to define a new functional integral that only integrates over physically distinct configurations.  I have seen how, by assuming a symmetry, e.g. U(1) symmetry, one can derive some beautiful results, such as the Maxwell Lagrangian, as done by Peskin and Schroeder. But why demand that there be gauge symmetries in the first place?


How do LIGO and Virgo know that a gravitational wave has its origin in a neutron star or a black hole?

It is being said that gravitational-wave detectors are now able to distinguish neutron star waves from those originating from black holes.  Two Questions:   How do LIGO and Virgo know that a gravitational wave has its origin in a neutron star or a black hole, if their gravitational fields, except for their intensity, are identical in that space beyond the radius that defines them? Is this identification accurate and reliable?


Installed as a dual boot ubuntu 13.04 alongside win8 and no grub?

i previously had windows 7 on my machine when i bought it i installed win8 now but i wanted to try out ubuntu so i installed alongside win8 but there was no grub screen to choose ubuntu.. if anyone knows of a way to fix this please let me know !! THANK YOU


list automatically changing without reference

I have a list of links which i am getting from BeuitfulSoup object, after links2=links1then i edited links1 ,but links2 got changed as well so i test in IDLE.  Example of a list which i want to modify but keep the original one intact, how can i do it?  a=[1,2,3] b=a a.append(4) print b   Output  [1, 2, 3, 4]   i want b to stay [1,2,3]


What is development by inspection (DBI) and how is it done?

While reading  I noticed the DBI concept.  If I understand correctly, the idea is to develop a film while being able to see the progress (and apply the fixer once you're happy with the result).   Is that what it means?   If so:   I assume you can't use the same chemicals you'd use normally, right? (I'm more interested in B/W, if it makes a difference) A green filter is mentioned; is there a reason why green is used? Any other relevant skills or knowledge needed to do DBI?


Two 401k accounts with two employers, should I combine them?

I currently have two 401(k) investment accounts, one is with my old employer, whom I left in 2015, and the other is with my current employer.   The old 401(k) has been steadily making money off my previous contributions (have earned about $1000 in the last 2 years), however, I do not know if or how to change my portfolio for this particular account.   My current 401(k) that I contribute to is with Vanguard and I am somewhat able to adjust my portfolio.   A few details:   25 years old Current company only matches up to $1,000 annually The current combined total of both is ~$10,000 (about half in each account)   Should I transfer my old 401(k) into the current 401(k) account, leave them as is, or transfer and combine in a completely new investment company?


Any advantage to installing Ubuntu-only system with UEFI vs Legacy?

I'm building a new Ubuntu/Mythbuntu system.  It's not dual-boot with Windows or any other OS.  New motherboard supports UEFI (of course).  Should I install it as UEFI or stick with Legacy?  I ask because I've been having some trouble trying to install as UEFI (depending on Ubuntu/Mythbuntu flavor used, it either fails during install or on first boot).  That will be another thread if it turns out UEFI is the "preferred" way to go.


The  package redefines the \dots command so that it "guesses" the correct height of the dots with respect to its context. For example  $x, \dots, y$   will produce three lowered dots, aligned with the commas. While  $x \to \dots \to y$   uses centered dots that align with the arrows. However, if I define my own macros, amsmath can no longer guess and it always uses the lowered dots. For example  \newcommand{\myto}{\to} $x \myto \dots \myto y$   uses the wrong dots. How can I tell amsmath that I want centered and not lowered dots?  Btw., I know about \cdots but what I want is \dots to still be able to guess the correct ones automatically.


What about the reciprocal of Heine theorem?

$i.e.$ What are the subsets $H$ $\subset$ $\mathbb R$ such that all continuous function $f$ $:$ $H$ $\to$ $\mathbb R$ is uniformly continuous ?  Compact sets of course, but think about $\mathbb Z$ or more complicated subset.


No hungarian letters with UTF-8 encoding in php

I have a problem with my Display datas from Mysql php page. My problem is when I want to display some hungarian specific chars like "á" or "é" they replaced with question marks. I set all of my tables and rows to utf8_hungarian_ci, and the entire table and rows to utf8_unicode_ci, but it doesn't work. A tried in my php code to set this "header(Content-Type: text/html; charset=utf-8)" at the beginning of my php code, but i haven't got any success with that. Can anybody help me? Thank you! Edit: The code that I trying to use:  <?php header('Content-Type: text/html; charset=utf-8'); function testfun() {   $con=mysqli_connect('blabla"); // Check connection if (mysqli_connect_errno()) { echo "Failed to connect to MySQL: " . mysqli_connect_error(); }  $result = mysqli_query($con,"SELECT * FROM adatok");  echo "
";  $i = 0; while($row = $result->fetch_assoc()) {     if ($i == 0) {       $i++;       echo "
";       foreach ($row as $key => $value) {         echo "" . $key . "	";       }       echo "
";     }     echo "
";     foreach ($row as $value) {       echo "" . $value . "	";     }     echo "
"; } echo "
";  mysqli_close($con);   }    testfun();  ?>


Does the magnitude of covariance have any real meaning?

I am not able to understand logic behind coming up with this formula for covariance. We know that the sample covariance formula is:    $${\rm Cov}(x,y)=\frac{\sum(x_i - \bar{x})(y_i - \bar{y})}{n-1}$$  I am not able to understand the logic behind the numerator. Why are we multiplying the terms? I mean, I know we need to find the change in x is appearing along with change in y (if they co-vary), so this formula will give direction of that change in terms of sign of the number that you get after substituting the values in the formula. And also we will be able to make some comparisons, e.g., having a covariance of 50 is more evidence of x and y moving together than having it as 30. So their ordering will make sense. But if you just think of a single value of covariance without having to compare it with anything else, does it have any real intuitive meaning (just the number in itself)? For example, in case of variance or standard deviation one can easily see that it is average number of 'deviation from the mean' per data point in the sample. But here in case of covariance, I am not able to come up with any such intuitive understanding.     As I was adding tags for this question just now—I saw this as the tag description for the covariance the tag:      Covariance is a quantity used to measure the strength and direction of the linear relationship between two variables. The covariance is unscaled, & thus often difficult to interpret   So probably my difficult to understand covariance can be attributed to this.


Google Chrome 81 doesn't launch after installation in Ubuntu 18.04

I'm using Ubuntu 18.04.4 LTS. I have installed Chrome browser v81 but when I'm trying to launch the browser, I'm getting below error message:  [22725:22742:0418/111128.075479:ERROR:disk_cache.cc(184)] Unable to create cache [22725:22725:0418/111128.075495:ERROR:process_singleton_posix.cc(404)] readlink failed: Permission denied (13) [22725:22725:0418/111128.075524:ERROR:process_singleton_lock_posix.cc(19)] readlink(/home/ewsetiawan/.config/google-chrome/SingletonLock) failed: Permission denied (13) [22725:22742:0418/111128.075531:ERROR:shader_disk_cache.cc(606)] Shader Cache Creation failed: -2 [22725:22725:0418/111128.075545:ERROR:process_singleton_posix.cc(256)] readlink(/home/ewsetiawan/.config/google-chrome/SingletonLock) failed: Permission denied (13) [22725:22725:0418/111128.075552:ERROR:process_singleton_posix.cc(280)] Failed to create /home/ewsetiawan/.config/google-chrome/SingletonLock: Permission denied (13) [22725:22725:0418/111128.075565:ERROR:process_singleton_posix.cc(404)] readlink failed: Permission denied (13) [22725:22725:0418/111128.075574:ERROR:process_singleton_lock_posix.cc(19)] readlink(/home/ewsetiawan/.config/google-chrome/SingletonLock) failed: Permission denied (13) [22725:22725:0418/111128.075607:ERROR:chrome_browser_main.cc(1408)] Failed to create a ProcessSingleton for your profile directory. This means that running multiple instances would start multiple browser processes rather than opening a new window in the existing process. Aborting now to avoid profile corruption.   Uninstalling and reinstalling doesn't solve the problem. What to do The browser isn't launched. How can I do to solve this problem?


Create points symbology with more than one parameter

In QGIS i would like to create symbology for points layer where the symbology will take into account more than one parameter (currently two). i.e.: My points layer has street names and house numbers and i would like to have each street with a different symbol and each number with a different color. Each street_name+house_number is unique. I wouldn't mind if distant streets share symbols.   What will be the best way to achieve it in QGIS? Consider that Rule-based symbology is manual and i have many streets, i don't see it as a good solution for this specific problem.


Variable expansion succeeds with echo but fails without a command (execution by expansion)

I created a file nano ~/uncwe/configurations/variables.sh. This file contains:  set -a rse="~/${repo}/internal_software/rse.sh" set +a   I sourced the file, then tried to execute:  ${rse} bash ${rse}    Both output No such file or directory, although, echo ${rse} returns:     ~/uncwe/internal_software/rse.sh   That's odd to me, because that file ~/uncwe/internal_software/rse.sh is alive and kicking, and I can run it directly by:  ~/uncwe/internal_software/rse.sh   In this case, the file runs just fine.  Hence I'd like to ask why is the file's execution fail when done by expanding the variable that contains its path as in both ways shown above?  It is important to me to run this file from expanding the variable (and not use an alias) because I need to run that script inside scripts (and aliases aren't good for that in the current release of Bash).


Why are there separate copies of the Terms of Service per site, if the link in each site just goes to Stack Overflow's version?

I noticed that each site in the network has its own copy of the Terms of Service, e.g. , , , etc.  But the link to the terms in the footer of each site just goes to Stack Overflow's version, not the local per-site copy.  In the past, there used to be a single copy of the terms on stackexchange.com, but since the terms were recently changed in May 2018, the current arrangement of having a copy on each site was adopted.  What's the point of having a copy of the terms on each site if the footer link just goes to Stack Overflow's version?  (Side note: the old link to the terms hosted on stackexchange.com now redirects to Stack Overflow's version as well.)


Difference between echo -e and echo -e " "

What is the difference between running the echo command with argument passed in quotes v/s without quotes? echo -e hi\n    # Output = hin echo -e "hi\n"  # output = hi  (with extra new line) echo -e hi\\n   # output = hi  (with extra new line)  I want to understand the difference between the above 3 commands and how the bash interprets them? P.S - I am trying to explore the echo command with the option -e


I was once told by an English professor that a comma should never be used before but in a sentence. For years, I have followed her advice but sometimes I just feel like it just needs to be there. On the other hand, my brain also tells me that the word but is, in a sense, performing the same function as a comma in the sentence.    Does anyone know if there is a rule for this?


Beginner at Python : Exiting inner for loop soon as completing the job

After finding the first list1[k] > list2[m,0] I want to increase the the value of list2[m,1]. The main thing is that after the first found value and increase of list2[m,1] I dont want to continue the inner for loop. I tried to use break at the end but it didnt work.Any suggestions?    for k in range(0, rang+1):     for m in range(0, len(dir)): # len(dir) is the row number of list2        if list1[k] > list2[m,0]:         list2[m,1] += 1


Putty ssh client fails with Segmentation fault after upgrade to 17.10

sudo putty fails with:  Invalid MIT-MAGIC-COOKIE-1 keyUnable to init server: Could not connect: Connection refused (putty:2153): Gtk-WARNING **: cannot open display: :0   putty fails with  Segmentation fault (core dumped)   I uninstalled and purged putty. After reinstalling the errors remain.


Academic papers using Stack Exchange data

As a result of  myself, the need arose to track other Stack Overflow-based research. The following is an attempt to list the academic papers mentioning Stack Overflow/Exchange or using Stack Exchange data. This also includes the works mentioned in  that started the trend, as well as two other questions on meta, , and . If you know of papers that are not listed, please edit the answer directly. I realised it might be useful to have all the BibTeX entries in a single file, so I started .


Why is Wolverine not able to walk or run properly in Logan?

In Logan, Wolverine seems to have a problem in his right leg from his first appearance. We can see that until the last scene before he took the full dose of the drug, he was barely able to run.   What caused that is not specified anywhere in the movie. Is there any information available on it?


I have raster image that projected by WGS1984 UTM Zone 37N. But my shapefile was Adindan UTM Zone 37N. Due to this, it doesn't overlay the same. I tried to define projection for the raster image to Adindan UTM zone 37N, But not match. So, how can I display the raster image in Adindan UTM Zone 37N without change WGS1984 UTM Zone 37N?


Conditions under which group solvability is invariant under an homomorphism.

Let $G$ be a solvable group and $f: G \rightarrow H$ an isomorphism. My question is if $H$ is a solvable group.   Let $1=G_0 \trianglelefteq G_1 \trianglelefteq ... \trianglelefteq G_n = G$ be a normal series of $G$ whose factors are abelian groups. Clearly, $1=f(G_0) \trianglelefteq f(G_1) \trianglelefteq ... \trianglelefteq f(G_n) = H$ is a normal series of $H$ but are the quotients abelian?  Is there a weaker condition for invariance?


I was playing MTG with my lady and came across this scenario: She had a creature with 2 +1/+1 counters, and 2 . She attacks with the creature, both triggers hitting the stack. I play  while the triggered abilities on the stack, killing the creature. Since the creature isn't around anymore, I believe the triggered abilities will fizzle, meaning she doesn't get the lands as no +1/+1 counters are placed as the creature is dead. Can anyone confirm my resolution?


How can I compute the integral $\int_{0}^{\infty} \frac{dt}{1+t^4}$?

I have to compute this integral $$\int_{0}^{\infty} \frac{dt}{1+t^4}$$ to solve a problem in a homework. I have tried in many ways, but I'm stuck. A search in the web reveals me that it can be do it by methods of complex analysis. But I have not taken this course yet. Thanks for any help.


This is not a boarding card .... go to check-in for visa check and boarding card?

i just bought a Ryanair plane ticket from Marrakech to Milano-Bergamo, but I see on the ticket that this is not a boarding card and I need a visa. I'm a Moroccan passport holder  who lives in italy, so I have  an italian identity card and an unlimited residence permit, and actually I never needed a visa to travel to/from  Morocco/ Italy. I traveled to Marrakech one month ago with a normal ticket ( with the QR code). So now i have to go back to Italy. I don't know why i received a boarding pass like that.... Can someone help  me, please?


I am reading Goodfellow's original  on GANs.  What I struggle to understand is his notation of the subscript in expected values.  $\mathbb{E}_{\boldsymbol{x} \sim p_{data}(\boldsymbol{x})}$ ....  If I understand it correctly then $\boldsymbol{x}$ is a realization of some random variable $\mathbf{x}$, but how can there be an expectation wrt. $\boldsymbol{x}$?  Or is $\boldsymbol{x}$ a random variable?  Thank you.  Edit: I do not think this is duplicate, as the referenced question does not answer what $\boldsymbol{x}$ means.


I am making a simple matchmaker as a learning project in JAVA. My program so far just asks a few questions, but I wanted to do gender specific questions, so I asked for their sex (m or f) and then attempted to add a message that only showed if sex was m. The dialog should say "well done, you are male!". Else it restarts method. Every time, no matter what I type it restarts the program.  Here is my code:  import javax.swing.JOptionPane;  public class Main {      public static void main(String[] args){         setVars();     }      public static void setVars(){         String name = JOptionPane.showInputDialog(null, "What is your name?");         String sAge = JOptionPane.showInputDialog(null, "What is your age?");         String sex = JOptionPane.showInputDialog(null, "What is your sex?\n(Enter  m or f)");          if (sex == "m"){             JOptionPane.showMessageDialog(null, "Well done, you are male.\nKeep Going!");         }         int age = Integer.parseInt(sAge);         String chars = JOptionPane.showInputDialog(null, "Name three charectaristics");     } }


Do t-test of two sample groups with variance 0

I'm trying to do a Welch's t-test of two sample groups which turn to have estimated variance equal to 0.  As could be seen from wikipedia page of Welch's t-test: , the formula for calculating the t-stat:  $$ t= \frac{\overline X_1 - \overline X_2}{\sqrt{\frac{s_1^2}{N_1} +\frac{s_2^2}{N_2}}} $$  contains 0 at the denominator and the t-stat could not be calculated (obviously my C++ program retuns me a NaN value...)  I need a way to handle this an calculate the t-test anyway, could you tell me how to proceed in these cases?


Since I want to take advantage as much as possible of the space in a poster I'm making I want to make the footnotes (that include citations) appear continuous (in one line). After searching I found  that says that I can achieve that using the footmisc package.  The problem is that when I use it, my footnotes disappear. Consider the following example code. If you remove the \usepackage[norule,para]{footmisc}, the footnotes appear properly.  \documentclass{beamer} \usepackage[norule,para]{footmisc} \usepackage{biblatex}  \begin{document}  \begin{frame}[fragile]   \begin{columns}     \begin{column}{.49\textwidth}       \begin{beamercolorbox}[center,wd=\textwidth]{postercolumn}         \begin{minipage}[T]{.95\textwidth}           \parbox[t]{\textwidth}{             \begin{block}{Test}               this is some test text\footnotemark             \end{block}}         \end{minipage}       \end{beamercolorbox}     \end{column}     \footcitetext{osborne-rubinstein}     %Second Column %     \begin{column}{.49\textwidth}       test\footnotemark     \end{column}     \footcitetext{test}   \end{columns} \end{frame}  \end{document}   Is there some problem with the footmisc package and the the beamer class or am I doing something wrong?


finding which program produces a log file

I am using Ubuntu 15.10 and I have an email account configured on the terminal.   Probably a left-over from the time I tried to configure that account, I have some logs being printed to a file in my home directory a couple of times day.   An example of a log (one line, split here for readability):  28 12:36:02 host=smtp.gmail.com tls=on auth=on   user=***@gmail.com from=***@gmail.com recipients=&&& smtpstatus=553   smtpmsg='553 5.1.2 The recipient address <&&&> is not a valid RFC-5321 address. q65sm28155223wmd.6 - gsmtp'   errormsg='recipient address &&& not accepted by the server' exitcode=EX_DATAERR   It is printed to ~/msmtp.log  My question is how can I discover where does this printing comes from in order to kill it?  Solution: The log was printed by msmtp itself. A quick look at the msmtp manfile showed that the configuration file is ~/.msmtprc . I edited this file to change the log file.


Evaluate   $$ \int_0^{+\infty} \frac{1}{(1+x^2)(1+x^{\phi})}\, dx \, \, \, (\phi>0) $$  See my answer below for a solution using a nice substitution.