What is the best way to explain how to choose between "its" and "it's"?

Probably one of the most frequent grammar mistakes in the English language is:     The dog sat on it's mat.   Since spelling checkers don't catch it, and it is even logical, since you would correctly write:     The dog sat on Fluffy's mat.   What is the best way to explain to a learner of English how to choose between it's and its?


If an object is free falling under gravity, then where is the pseudo force applied?

If I am travelling in a train and the train accelerates forward then I experience a pseudo force backward. But if someone is free falling under gravity where does he experience pseudo-force because pseudo is experienced in an accelerated frame.


How to disable sleep/screensaver Kubuntu 12.04 LTS and VLC?

I watch VLC for a while, then about 15 min. later, it sleeps.  Where can i find the how to disable the screen-saver or how to disable sleep?


If $0<x<1$ and $0<y<1$ then prove $x+y<1+xy$

I first came across this problem on  and have tried to solve it myself. Here is what I did (may seem laughable to those who know the answer!):  Let $a = x+y$ and $b=1+xy$  I figured that to prove $x+y<1+xy$ to be correct, I need to find an equation which will allow me to plot a graph, $d = b-a$, showing that $b - a$ approaches 0, but never touches it. This is where I am stuck and don't know how to proceed. Presumably, if my method has been correct so far, I need to simplify it in some way so that there is one variable only.   (I haven't really been taught anything like this at school but since I want to study maths later on, I figured it may be helpful to try some challenging questions like this. This seemed fairly easy at first, but can't get my head around it, so any helpful answer which I can learn from is greatly appreciated.)


How to verify observe or check the source of AC line noise

I'm using a complicated system which reads pressure measurements and sends to an ADC. I will not go to details of the system because I just noticed a big difference due to different AC mains connections.   Below is a basic illustration of the system:    The system is always in the second floor. If I plug the AC power cord to the mains in 2nd floor I get a very noisy spiky output. Both with 2 prong and 3 prong connector. So it seems its not earth related.  But if I leave the system in the second floor and plug the AC power cord in the 1st floor I get a very clean output.  Below shows this difference. Both voltage is on vertical axis represents sensor data and scaled with factor 100.(For example 10 in vertical pressure axis is 0.1 Volt). These wild spikes are like HF noise.    I tested it many times and I'm sure this is the source of the noise. The place in the 2nd floor has an AC motor and florescent lambs. But this happens some days. Some days not.  I mean if I use the mains power in 2nd floor for powering up the system I observe this on some days.  But if I use the 1st floor's plug there is never noise.  Something is causing noise on AC lines in the second floor.  Since neutrals are all connected in a building could it be the live is being exposed to noise in 2nd floor?   Can I measure/verify this with noise with a scope and a step down transformer? Or with an RC differentiator?


I  have a script which monitor a directory and call a function with certain arguments. And in this script a open file.log to explain what happened each time there is a new file in the monitored directory.  This is the prototype of my function :   def and_now_my_watch_begin(dir_to_watch, function_to_call, *args_for_function):   I would like to know if there was any way to get function's name like a function.name.to_str() or something like this ?


Function $\mathbb{R}\to\mathbb{R}$ that is continuous and bounded, but not uniformly continuous

I found an example of a function $f: \mathbb{R}\to\mathbb{R}$ that is continuous and bounded, but is not uniformly continuous. It is $\sin(x^2)$. I think it's not uniformly continuous because the derivative is bigger and bigger as $x$ increases. But I don't know how to prove this is uniformly continuous. Is $\sin(x^2)$ uniformly continuous then? if it isn't, can you guys think of any other examples? thanks


“E: The list of sources could not be read.” while trying to update

i am get this error while trying to run update command  mostafa@mostafa-Satellite-C660:~$ sudo apt-get update E: Type '<!DOCTYPE' is not known on line 1 in source list /etc/apt/sources.list.d/playonlinux.list E: The list of sources could not be read.   How can i solve this? i am using ubuntu 14.04 LTS


So, I know that there are many questions on stack overflow out there that are trying to handle circular dependencies. But none of those could really answer my question, if it is possible to have two classes know each other, and, more importantly, access information from each other. So, basically, I have read that you could use forward decleration, but with forward decleration, I couldn't access any fields. Maybe I should also add that I am really new to C++.But enough talking, let's get to an example: Let's say we have a class called Scene and a class called EntityBase, which are defined as following: EntityBase.h #pragma once #include <string> #include "Scene.h"  class EntityBase { public:     std::string entityId;     Scene scene;       EntityBase(std::string entityId);      /*      This method will be called when this object is added to the scene      */     void onAddedToScene(Scene* scene);      /*     This method will be called when this object is removed from the scene     */     void onRemovedFromScene(Scene* scene); };   Scene.h #pragma once #include <vector> #include <string> #include "EntityBase.h"  class Scene { public:     std::vector<EntityBase> entities;     std::string name;      Scene(std::string name);      void addToScene(EntityBase& entityBase); };   The question arises, How can I print out the name of Scene(and use every method of Scene) while EntityBase can fully access Scene too? So, I'd really appreciate if you'd tell how to do this, because I will probably need to access every field and/or method later.


How to seal a foundation wall hole 7' feet deep around a 2" pipe in a cold heavy snow climate

Our foundation has a 2" hole for the water main / well pipe which is about 7' below the ground outside. During spring thaw when there is several feet of snow melting, the ground gets saturated, and water leaks in between the pipe and the cement foundation. Ideas for repairing from the inside would be ideal, however even options for what we can do by digging up around the foundation on the outside are appreciated. This  suggests caulk or cement (perhaps this means ?) will fail, epoxy is better though will eventually fail due to rigidity, preferring instead injecting a “high-viscosity polyurethane” (Perhaps  or  ?). I also found this video suggesting this  I've found 4 existing questions here, though no conclusive answer:     talks about a foundation seal compound on the outside, though not specific enough to figure out which to try or how to apply. talks about cleaning and packing around the pipe from the inside with  or   --> these seem to be roofing products, do we have anyone who can verify success with this approach?      suggests using epoxy, though as I summarized above, it seems some sites suggest epoxy is too rigid and thus will fail over time.      No proposed solution.      Proposes  --> The product page doesn't seem to talk about sealing leaks in foundation, is this the right long term solution? Proposes expanding foam is not good (doesn't elaborate on why). proposes a channel outside the house to keep water away --> won't work for us, as this is from spring melt of many feet of snow (the channel would be buried).


$ \forall \epsilon \in \mathbb{R}^{*}_{+} , | x -y | < \epsilon \iff x = y $

Prove that for all  $ \epsilon > 0, \epsilon \in \mathbb{R} $ for every $ x, y \in \mathbb{R} $ if $ | x - y | < \epsilon \iff x = y$  (this question has similar ones in, but this one has the full proof, not only the hint).


Where does the $i$ come from in the Schrödinger equation?

I am currently trying to follow Leonard Susskind's "" lecture series on quantum mechanics. (I know a bit of linear algebra and calculus, so far it seems definitely enough to follow this course, though I have no university physics education.)  In general, I find these lectures focus a bit too much on the math and not really on the physical motivation behind it, but so be it (if there are other courses aimed at those with reasonable math skills that focus more on physical meaning, let me know!). However, that's only indirectly related to what my question is about.  In , Susskind sets out to derive an expression for what he earlier labelled the time-development operator $U$:  $$|\psi(t)\rangle = U(t)|\psi(0)\rangle$$  He starts out as such:  $$U(\epsilon) = I + \epsilon H$$  which makes sense because the change in time will have to be small, i.e. on the order of a small $\epsilon$. However, he then goes ahead and changes this into:  $$U(\epsilon) = I - i\epsilon H$$  which of course is still fine, because we still don't know what $H$ is supposed to be. Now my problem lies with the fact that Susskind then proceeds to derive an expression for $H$ and, subsequently, the Schrödinger equation in which it figures, from the above equation. The $i$ never gets lost and ends up in that equation.  Could we not just as easily have left the $i$ out, or put a 6 or whatever there? Why put $i$ there? I finished the entire lecture hoping Susskind would get back to this, but he never does, unfortunately. (Which is, I guess, another symptom of this course, with which I'm otherwise quite happy, occasionally lacking in physical motivation.)   For those of you who know this lecture, or similar styles of teaching: am I missing something here? Alternatively, a general answer as to why there is an $i$ in the Hamiltonian and the Schrödinger equation?


Find a bijection between $[0,1)\sim(0,1)$.   Well I know that $$[0,1)\sim(0,1)=[0,\frac{1}{2})\cup [\frac{1}{2},1)\sim(0,\frac{1}{2}]\cup [\frac{1}{2},1).$$  So I found this function: \begin{align} f(x)&=-x+\frac{1}{2} &\text{ if } x\in [0,\frac{1}{2})\\ f(x)&=x &\text{ if } x\in [\frac{1}{2},1)\\ \end{align} Which is surjective but not injective because $f^{-1}(\frac{1}{2})=0,\frac{1}{2}$. Is this the correct conclution to make about $f(x)$? What is a function that works/is bijective?  This question is different than the other questions on bijections between simple real intervals because I want feedback on this specific function, $f(x)$, and I find mapping from a half closed set to an open set more confusing than mapping an open set onto a closed set.


Can I set Ubuntu 12.10 to automatically reboot to Windows once only?

Is there some way when I'm in Ubuntu 12.10 that I can set it to reboot automatically to Windows just once, so that when I'm in Windows I can reboot and it will automatically boot back into Ubuntu?  I need this because often when I travel I access my home computer for email and other personal info that I don't want to travel with or leave to the tender mercies of the "cloud".  On rare occasions, I need to temporarily boot into Windows 7 to do something Windows-specific, but then I want to be able to boot back into Ubuntu because that's where most of my computing takes place.  Any ideas?  Thanks in advance!


Let $a$, $b$ and $c$ be positive real numbers with $abc=1$. Prove that   $$ \frac{a^{n+2}}{a^n+(n-1)b^n}+\frac{b^{n+2}}{b^n+(n-1)c^n}+\frac{c^{n+2}}{c^n+(n-1)a^n} \geq \frac{3}{n} $$   for each integer $n$.   I have used Cauchy-Schwarz inequalities and Jensen inequality. But I am stuck. I need some idea and advice on this problem. Induction would be cruel.


How to output comments on comments in cycle?

Structure table Comments:  id (int 11) NewsIdn (varchar 10) CommentsIdn (varchar 10) // ForCommentsIdn (varchar 10) //have CommentsIdn comments(answers) reply to which users  Text (varchar 100) DateCreate (datetime)   I would like output comments and comments(answers) for comments, ie. structure output data on page:  -- comment 1 -----answer on comment 1 --------answer on answer on comment 1 (№1) --------answer on answer on comment 1 (№2) --------answer on answer on comment 1 (№3) ----------answer on answer №3 on answer on comment 1 ------------- ---------------N                        ***                        ***                        *** -- comment 2 -----answer on comment 2 --------answer on answer on comment 2 (№1) --------answer on answer on comment 2 (№2) --------answer on answer on comment 2 (№3) ----------answer on answer №3 on answer on comment 2 ------------- ---------------N                         ***                        ***                        *** -- comment N -----answer on comment N --------answer on answer on comment N (№1) --------answer on answer on comment N (№2) --------answer on answer on comment N (№3) ----------answer on answer №3 on answer on comment N  AND IE.   I get first comment:  SELECT * FROM COMMENTS WHERE NewsIdn='1122121' // value NewsIdn as example   But How output comments on comments in cycle ?  Tell me please how make it?


I received a mail today from Academia.edu (a site I wasn't previously aware of), asking me to confirm that I co-authored a paper with a colleague.  Having looked into it a little it sounds like it might be a useful site - the idea of a "social network for scientists" is one I've seen the need for in the past. However, partly due to bad experiences with the seemingly similar ResearchGate, I'm also skeptical.* Without signing up for an academia.edu account the site doesn't offer much information, so I would like the following information:   What specific features does academia.edu offer to its users? Is it genuinely useful for any of the following purposes (each of which seems genuinely needed)   as a platform for networking with academics for discovering relevant research as an effective system for post-publication peer review for organising references among a small team of people working on a project  Will it send out mails to my colleagues without my express and explicit permission? (I.e. are the mails I received today the result of a deliberate action by my colleague, who is aware that I will be emailed and wishes me to join the site; or are they essentially spam from a social networking site aggressively trying to expand its user base?) It's clear from its  that it's a private, venture-capital funded company. What is its business model?   In short, is this a site that has some genuine utility for academics, or should I just ignore it?  *I've never signed up for ResearchGate but I regularly receive spam from it purporting to be from my colleagues, who aren't aware that it's being sent on their behalf. I would be mortified if my senior colleagues received such mails claiming to be from me, so I won't touch it with a barge pole.


Is there any trick to calculate $\int\ln(x+\sqrt{x^2-1})dx$ faster?

$$\int\ln(x+\sqrt{x^2-1})dx$$ To evaluate the integral we can apply integral by parts (using $u=\ln(x+\sqrt{x^2-1})$ and $dv=dx$). but my question is: is there other approach to evaluate the integral faster? I think there might be something because we can write it as: $$\ln\left(x+\sqrt{x^2-1}\times\dfrac{x-\sqrt{x^2-1}}{x-\sqrt{x^2-1}}\right)=\ln\left(\cfrac1{x-\sqrt{x^2-1}}\right)=-\ln(x-\sqrt{x^2-1})$$ But I don't know how to use this.


PostgreSQL JSONB Execution Plan with high Offset

How does PostgreSQL work i.e. the execution plan on JSONB query with high Offset number and how to improve the performance? Considering the below "Test Query", help me to clarify the following:  As the SubYear is 2050 which is a future date on which there are no cases available yet does it require a full table scan or is there any alternative approach to tune this ?  When the same query is modified to retrieve the data with "SubYear" < 2050, there are lot of results i.e. 35k+. How does PostgreSQL works on it when the Offset is set to a high number lets say 30k ?   Test Query : select     * from     sub_test df,     jsonb_array_elements(json_data) jba where     (jba->>'name')::text = 'SubYear'     and (jba->>'value')::numeric > '2050';


Question about determinant of a block matrix

I was studying block matrices and suddenly this question came to my mind. Let $A, B \in \Bbb R^{n \times n}$. From this , $$\det \begin{pmatrix} A & B\\ B & A\end{pmatrix} = \det(A-B)\det(A+B)$$ even if $A$ and $B$ do not commute. Does a similar condition hold for the following block matrix? $$\begin{pmatrix} A & -B\\  B & A \end{pmatrix}$$


hyperref: how to format text in a forms text-field

I would like to pre-format the text in a form text-field, e.g. make it bold, italic or use a specific font. The following code generates a simple text-field:  \documentclass{scrreprt} \usepackage{hyperref} \begin{document} \textbf{The Text Field} \begin{Form} \TextField[]{\ } \end{Form} \end{document}   Is it possible to pre-format the text in the text-field? The hyperref package manual (10/2011) speaks of an optional parameter format and the use of JavaScript to format the field. Can this be used to format the text in the field? And if yes, how is it done? (I am not proficient in JavaScript)


How to convert string to datetime in python?

I want to convert this string "Fri, 03 Jun 2016 08:01:26 GMT" to datetime in python.  Thanks in advance


Is it ok that LaTeX doesn't have a wordcounter?  texcount is a very valuable external esource to determine how many words you have in your document, but it relies . But instead of using a console to figure this out it could be a good option to a have a visual input on how long a document's pdf gets while running one compilation after another.    One possible way to have wordcount done in a visual manner would to have the number of words signaled and printed to the resulting pdf on a certain amount of periods. One could have this wordcount set for each paragraph, page, chapter, and/or full text. How could this be done?   How do get wordcount on our working file pdf?  Options could be the total number in the 1st page, or as draft options, or as a separate page. The possibilities are endless. This SE site is full of places where it's stated that LaTeX can do anything. A comment ot this question explains quite well that tex is not optimal for word count so an external source is a good thing. But maybe there's some way to connect the external tool to tex?      if using luatex it might be more reasonable as you could count in lua without disturbing the tex macros so much   I'd prefer LaTeX but if luatex is a chance ... how would it work?    The other chance would have the result printed to the beginning of the preamble of the document in the master document where our main.tex file is. This has been suggested before and is not the main question here:


include plotmarks in the title of a plot

I want to use markers form \usetikzlibrary{plotmarks}, like: pentagon*, diamond*, square* and triangle* in the title of the plot. They work as markers in the plot but i get an error when in want to include them in the title (instead of the "x" in \mathbf{})    This is my code:  \begin{filecontents*}{data.txt} b d c 1 a 2    2 b 4    3 c 6    4 d 8    5 e 10   6 f 12   7 g 14   8 x 16   9 x 18   \end{filecontents*} \documentclass[paper=a4,ngerman,xcolor=dvipsnames]{article} \usepackage[ngerman]{babel} \usepackage[utf8]{inputenc} \usepackage{pgfplots} \pgfplotsset{compat=1.14} \usepackage{siunitx} \usepackage{caption} \usepackage{graphicx} \usepackage{lipsum}  \pgfplotscreateplotcyclelist{mycolorlist}{ blue!01!green,every mark/.append style={fill=blue!10!black},mark=+\\ }  \begin{document} \begin{figure}   \begin{tikzpicture}     \begin{axis}[         grid=both,         width=12cm,          height=9cm,         xtick pos=left,         ytick pos=left,         title style={draw,fill=none,name=legend},         title={%             ${\color{red}\mathbf{x}}=\SI{100}{\kilo\Hz}$,             ${\color{red}\mathbf{x}}=\SI{10}{\kilo\Hz}$,             ${\color{red}\mathbf{x}}=\SI{1}{\kilo\Hz}$,             ${\color{red}\mathbf{x}}=\SI{100}{\Hz}$,             ${\color{red}\mathbf{x}}=\SI{10}{\Hz}$,             ${\color{red}\mathbf{x}}=\SI{1}{\Hz}$},         xlabel={R}, ylabel={Z},          legend style={at={(0.02,0.98)},anchor=north west,cells={anchor=west}},         legend style={font=\footnotesize},         cycle list name=mycolorlist,         scatter,         point meta=explicit symbolic,         scatter/classes={           x={},% empty argument means: use the default style                  g={mark=o,red!10!black},           f={mark=square*,red!20!black},           e={mark=diamond*,red!30!black},           d={mark=triangle*,red!40!black},           c={mark=pentagon*,red!50!black},           b={mark=*,red!60!black},           a={mark=oplus,red!70!black},           z={mark=*,red!80!black}           },         ]         \addplot table [x=b,y=c, meta=d]{data.txt};          \legend{Z}    \end{axis}   \end{tikzpicture} \end{figure} \end{document}   \pgfuseplotmark{square*} works but it also changes the title.   . . . title style={draw,fill=none,name=legend},         title={%             ${\color{red}\pgfuseplotmark{o}}=\SI{100}{\kilo\Hz}$,             ${\color{red}\pgfuseplotmark{square*}}=\SI{10}{\kilo\Hz}$,             ${\color{red}\pgfuseplotmark{diamond*}}=\SI{1}{\kilo\Hz}$,             ${\color{red}\pgfuseplotmark{triangle*}}=\SI{100}{\Hz}$,             ${\color{red}\pgfuseplotmark{pentagon*}}=\SI{10}{\Hz}$,             ${\color{red}\pgfuseplotmark{*}}=\SI{1}{\Hz}$,             ${\color{red}\pgfuseplotmark{oplus}}=\SI{20}{\mHz}$},   It looks like this:    After using \def\showmark#1{\tikz[baseline]\node[red]{\pgfuseplotmark{#1}};} the problem with the y-alignment is fixed, but the title is not centered anymore.    Using \showmark{square*}=$\SI{100}{\kilo\Hz}$ instead of \showmark{x}=$\SI{100}{\kilo\Hz}$ leads to:


How to iterate over map in Salesforce Lightning Component?

I have a aura map attribute defined in my component file as below  < aura:attribute name="FilesNameMap" type="Map" />   But i am not able to understand how to iterate this in the component file as we know that the <aura:iteration> will work on List but not for Map.  Below is the code which i tried to iterate the Map but couldn't succeed.  < aura:iteration items="{!v.FilesNameMap}" indexVar="key" var="item" > //- logic </ aura:iteration >


How many times does Sneak Attack damage apply with several attacks?

I've designed for a campaign a duo of rogues. My character is as Sniper, and his follower is a Knife Mistress. Couple of questions about them.  Our party is about to ambush several trolls. My Sniper will hide near their camp, and shoot the weakest one when fight begins. His follower will then rush the troll and slice him in several pieces.  My Knife Mistress is high enough to have BAB +6/+1, is dual-welding daggers and has the Improved Two-Weapons Fighting feat. I get 4 attacks (+8, +8, +3, +3).  Now, does she deal Sneak Stab's damages on each attack (×4), only on main hand attack (×2), on only once per round (×1), as in 5e?


How to test if these two samples are from the same distribution? (These are tweets located near some tourist attractions.     If yes, is there a simple implementation in Python?


Prioritize non-accepted answers with more than 10:1 votes of the accepted

The SE model works well; OP asks and accepts, the community votes. You get two answers for the price of one; the one that works for OP and the one that works for the community.  Let's face it: sometimes OP is wrong.  I'm proposing that when a non-accepted answer's votes outweigh that of the accepted by at least 10:1*, the non-accepted answer is prioritized over the accepted one.  There are tons of examples across the network but for example, .  * Good ratio? Open question, please discuss.     This proposal isn't about "community accepted" answers per se, as suggested by , but merely about prioritization in the UI.


How can I colourfuly highlight some lines of an algorithm using algorithm2e?

I am trying to achieve something like this:     This image is linked from .  also provides a solution and seems simpler. Both answers deal with the algorithmicx package however. I am interested in the solution for the algorithm2e package.   I read the documentation of the algorithm2e package but didn't find an answer.   How can I achieve the colored effect?  EDIT:  Here is sample code to create a minimum working example.  \documentclass{article}  \usepackage[ruled]{algorithm2e} % http://www.ctan.org/pkg/algorithm2e  \begin{document}  \begin{algorithm}[h]  \caption{Evolutionary algorithm}   initialize population \;  \For( \emph{Evolutionary loop}){$g := 1$ to $G_{max}$}  {     do things \;     evolve population \;  }  celebrate \; \end{algorithm}  \end{document}


Mathematical proof that Fermions are half-integer spin particles, and half-integer spin particles are Fermions

See:        It was said that all fermions were half integer spin particles and all half spin particles were fermions. The Griffiths's testbook said that it could be proved in relativistic quantum and was taken as axiom in non-relativistic theory.  My question was that:   Could you give me the complete proof that Fermions are half integer spin particles, and half integer spin particles are Fermions? Is there a way to prove it without relativistic condition?


I have selected the unanswered tag's and seeing unanswered questions,   But when I am click the last page in paging , there can see answered questions in unanswered tag.   Is it bug? or correct?


Anomalous connection to china from debian server

TL;DR I didn't ask how to take care of my compromised server. I asked how to detect if a file is anomalous/extraneous/non-official. So this is not a duplicate of the question on compromised servers. This is obvious to anyone who take 2 minutes to read both questions before flagging as duplicate.  This morning we had a report of anomalous huge outgoing traffic from one of our debian servers. I tried to launch netstat -tpe as root and i found . unama is an unknown process, i searched online and i couldn't find any reference to it.  I launched a whois 173.254.230.36 and i found that the ip belongs to a chinese organization named meiyunla.  Then i tried with which unama, just to discover that it is an unreadable binary file located at /bin/unama.  Does anyone knows how to detect if this unama file is an official package to have or if it is something anomalous?  edit  Just for info, in the end it was some kind of a virus, which made our server part of a botnet. Deleting the file was useless, as after some minutes it was there again, using from 60% to 100% of the cpu.   We had to shut down the server and launch a new one, reinstalling all the software from scratch.  Just one thing: never use ssh password authentication on a public ip :)


As you may know the word "the" never appears on the label of products made in any country except the USA. I've found both "Made in USA" and "Made in the USA" on product labels, but which is the right one?


javascript event when you hit 'back' onto the page?

What event can i use to run code when a user visits another page then hits back to load my page again?  I wrote window.onload = function() { ... and it works when i hit refresh but not forward then back.


If $A\subseteq \{ 1, 2, ... 2n \}$ has $n+1$ elements, then it contains $a$, $b$ such that $a\mid b$

Let $ A $ be subset of of $ \{ 1, 2, ... 2n \} $, such that: $ Card(A) = n + 1$.  Prove that there exist at least two distinct elements $a,b$ in $ A $ such that: $ a \mid b $.    We have:  $$ \{ 1, 2, ... 2n \} =  \{ 1, 2, ... n \} \cup  \{ n+1, n+2, ... 2n \} $$  Intuitively, I know that every subset $ A $ of $ \{ 1, 2, ... 2n \} $ with $ n + 1 $ elements contains at least 2 elements $ a $ and $ b $ such: $ b = 2a $.  I don't know how to prove it mathematically. Thank you for your help.


I've seen the other thread  but I don't think the answer satisfied the actual question.  What I have continually read is that Naive Bayes is a linear classifier (ex: ) (such that it draws a linear decision boundary) using the log odds demonstration.  However, I simulated two Gaussian clouds and fitted a decision boundary and got the results as such (library e1071 in r, using naiveBayes())   As we can see, the decision boundary is non-linear.  Is it trying to say that the parameters (conditional probabilities) are a linear combination in the log space rather than saying the classifier itself separates data linearly?


I am wondering if I can use a list within a list. I know that the following sentence may seem as though it would be better if reworded, but I am using euphemisms and simplifications for what I am actually writing. I am trying to boil it down, so what you see below is just a microcosm of the sentence I am actually writing.      I went there because I was sad, lonely, foolish, and in need of shelter, love, and contentment.


Should a noun after the determiner *their* take in the form of singular or of plural?

Should I say     Some people use the word "flat" to describe their phone when its battery is dead.   or     Some people use the word "flat" to describe their phones when their batteries are dead. (I wanted to use "their" here to refer to the phone's instead of the people's)   or      Some people use the word "flat" to describe their phones when their battery is dead. (I wanted to use "their" here to refer to the phone's instead of the people's)   Which one is grammatically correct and why?


Why continue to teach and use hypothesis testing (when confidence intervals are available)?

Why continue to teach and use hypothesis testing (with all its difficult concepts and which are among the most statistical sins) for problems where there is an interval estimator (confidence, bootstrap, credibility or whatever)? What is the best explanation (if any) to be given to students? Only tradition? The views will be very welcome.


config ip adrress of a network interface through ubuntu terminal

I am trying to configure ip address of network interfaces through terminal in ubuntu systems. So far successfully changed the IP address and other things through editing the interface file in the directory /etc/network/interfaces.  Is there any possibilities in changing the ip address of the interface through terminal using commands like configuring ip address of the router.  Thanks,Mohan


How to fix cut romex line that was cut before receptacle

Can the romex be spliced in line and then shrink wrapped ? Or  bring receptacle outletbox closer to cut line.


Cartoon in a world with magic stones wielded by four children which combine to become stronger, and can summon creatures

Can you please help me find this animated show? There is a four member team with two boys and two girls. The boys can summon, with their stones, a rock golem (black wearing summoner) and a robot (orange wearing summoner). The two girls can summon something like a dragonfly (green wearing summoner, little girl) and the blue girl, I don't remember what she can summon.  I don't know where the animated show comes from.  By throwing the stone, they activate the stone's power. Each stone has different characters on it. When you don't match them correctly, you get a rebound effect.


Subsets $A$ of $\Bbb{Z}$ such that $xy \in A \implies x \in A, $ or $y \in A$. Primality of arb. subsets.

If $$ A \subset \Bbb{Z} $$ is such that $xy \in A \implies x \in A, $ or $y \in A$.  Then $A$ is either a prime ideal or ? Can we describe all "prime subsets" of $\Bbb{Z}$ that aren't prime ideals in one fell swoop? It's not just a subset closed under taking divisors, though those are counted, and so it's also not just a subset of negative prime numbers together with $\{0, -1\}$ either.


I've set up my own server and I'm really struggling to stop any outgoing email go to spam.  I've used allaboutspam and mail-tester.com to test it and they both come back with perfect results. No issues with reverse lookup, dkim or spf records. As far as I'm aware, I'm not on any black lists.  Below is the SPF record I'm using. The record name is cornhillfarm.co.uk  v=spf1 ip4:95.138.166.68 +a +mx ~all   Here's a brief clip of the header sent to gmail from the account  Delivered-To: me@email.co.uk Received: by 10.70.38.39 with SMTP id d7csp343605pdk;         Mon, 1 Dec 2014 08:46:42 -0800 (PST) X-Received: by 10.194.121.129 with SMTP id lk1mr30339186wjb.99.1417452401636;         Mon, 01 Dec 2014 08:46:41 -0800 (PST) Return-Path: <info@cornhillfarm.co.uk> Received: from grid3.woodbridgemedia.co.uk (grid3.woodbridgemedia.co.uk. [95.138.166.68])         by mx.google.com with ESMTP id xv5si30948234wjc.162.2014.12.01.08.46.40         for <me@email.co.uk>;         Mon, 01 Dec 2014 08:46:40 -0800 (PST) Received-SPF: pass (google.com: domain of info@cornhillfarm.co.uk designates 95.138.166.68 as     permitted sender) client-ip=95.138.166.68; Authentication-Results: mx.google.com;        spf=pass (google.com: domain of info@cornhillfarm.co.uk designates 95.138.166.68 as permitted sender) smtp.mail=info@cornhillfarm.co.uk;    dkim=pass header.i=@cornhillfarm.co.uk Received: from grid.woodbridgemedia.co.uk (grid3.woodbridgemedia.co.uk [127.0.0.1]) by grid3.woodbridgemedia.co.uk (Postfix) with ESMTPA id 32C32B4490 for <me@email.co.uk>; Mon,  1 Dec 2014 16:46:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cornhillfarm.co.uk; s=default; t=1417452404; bh=ARgAG5dpW0g4y11fXdXMWe/ZrWwUJlaCkCKhW45skOU=; h=Date:From:To:Subject; b=jMEbxoDGBpx5U9MGmvoQ11Xzf3SFy5EZbtS1j5uIysR9g/uc02vP/9anss7tUpKhn  QAML+qYjGGo7CU9lfdQqtyxhYukWHoZysQsy2nIVm/uYzmQDbWFiiiOJopMqQdgnkm  xArDQ7FucQgChsGF9g1iX1qyzpkMRGCbEJ1JFpOs=   Any ideas on what I've done wrong here to try and get it out of the spam folder?  If you need any other information about my setup that I've missed, let me know and I'll send the relevant information.  Thanks in advance!


Is there some clever way to do this in SQLite that I have not thought of? Basically I want to update three out of four columns if the record exists, If it does not exists I want to INSERT the record with the default (NUL) value for the fourth column. The ID is a primary key so there will only ever be one record to UPSERT. (I am trying to avoid the overhead of SELECT in order to determine if I need to UPDATE or INSERT obviously) Suggestions?  I cannot confirm that Syntax on the SQLite site for TABLE CREATE. I have not built a demo to test it, but it doesn't seem to be supported. If it was, I have three columns so it would actually look like: CREATE TABLE table1(      id INTEGER PRIMARY KEY ON CONFLICT REPLACE,      Blob1 BLOB ON CONFLICT REPLACE,      Blob2 BLOB ON CONFLICT REPLACE,      Blob3 BLOB  );  but the first two blobs will not cause a conflict, only the ID would So I assume Blob1 and Blob2 would not be replaced (as desired)  UPDATEs in SQLite when binding data are a complete transaction, meaning Each sent row to be updated requires:  Prepare/Bind/Step/Finalize statements unlike the INSERT which allows the use of the reset function The life of a statement object goes something like this:  Create the object using sqlite3_prepare_v2() Bind values to host parameters using sqlite3_bind_ interfaces. Run the SQL by calling sqlite3_step() Reset the statement using sqlite3_reset() then go back to step 2 and repeat. Destroy the statement object using sqlite3_finalize().  UPDATE I am guessing is slow compared to INSERT, but how does it compare to SELECT using the Primary key? Perhaps I should use the select to read the 4th column (Blob3) and then use REPLACE to write a new record blending the original 4th Column with the new data for the first 3 columns?


Can someone explain the overall plot device of Quiet Earth (massive spoilers)?

In the 1985 movie, Quiet Earth, the protagonist finds himself apparently the only man on Earth. Later, he finds:      two others who, like him were at the moment of death. He further determines that this is all due to an American experiment. Here's where I get a little fuzzy...was it that an entirely different reality was created and these folks were shunted to it, or did truly everyone else get wiped out? The ending, where the protagonist is shunted to a THIRD existence, seems to bear out the alternate reality existence...does this mean that the events are experienced only by the characters in the movie, and everyone else is just fine back in reality prime? Or did everyone get wiped out?   Which one is it?


Simple efficient concatenation of CSV files

Consider a large number of CSV files (*.csv) living in some folder. They all have the same exact header.    How can I efficiently concatenate them all into a single CSV file with the same single header?    I found a number of solutions that solve similar but more specific problems.         The current awk solution doesn't work.   $ cat concat_my_csv_files.sh     #!/usr/bin/env zsh     awk '         FNR==1 && NR!=1 { while (/^<header>/) getline; }         1 {print}     ' $1/*.csv > $2  $ ./concat_my_csv_files /some/path/to/csv/files/ full_join.csv   when I do:  grep -F column_A full_join.csv   I see several rows having it.


Is it possible to import Borderlands save data into the PC version?

With the release of Borderlands 2 imminent, I would like to play it on my PC.  An issue occurs, however, as I played the original on Xbox and would like to import that save data into Borderlands 2 when it comes out.    Now, as good as this game is, I do not want to buy it again and play through it for a 6th time, just get my data over to my PC.  Is there a tool similar to the import tools for Mass Effect that I can use to bring my Xbox data over?


If $f(\mathbb{C})\subset \mathbb{C}-[0,1]$ then $f$ is constant

If $f:\mathbb{C}\longrightarrow\mathbb{C}$ is an entire function such that $f(z)\neq w$ for all $z\in \mathbb{C}$ and for all $w\in [0,1]\subset \mathbb{R}$, how to prove that $f$ is constant (without using Picard's little theorem).   Any hint would be appreciated.


Let $A$ be connected and $U$ be clopen in $Y-A$. Prove $A\cup U$ is connected. [Dugundji]

This problem is on Topology - James Dugundji (1978), Chapter V (connectedness) Section 3, Problem 3. The problem says:  Let $A\subset Y$, where both $A$ and $Y$ are connected. Let $U$ be any set both open and closed (clopen) in $Y-A$. Prove that $A\cup U$ is connected.  What I have recognized so far is:  $Y-A$ is not connected by definition. $U$ is the union of its connected components by clopen's property. $A\cup B$ is connected if its connected component equals itself.  I don't know how to approach this problem using that properties.


How to create unsavable image as a figure?

Self-explantory question. I'm looking to make an image unsavable for someone browsing a doc online in overleaf, could be jpg, png or pdf.


Handling multiple regex matches in Ampscript

Given this string:  SET @text = "Salesforce Everything else"   And this function:  SET @matching = '\s+(?:[^>]*?\s+)?href="([^"]*)"' SET @output = RegExMatch(@text, @matching, 1)   How can I manage to find and print an arbitrary number of matches in my string? E.g. in above example, I would like to present e.g. a rowset with each URL in each row.


Imported TIF has dark gray background instead of white

using QGIS 2.6  I import a TIF file, and expect the import to show an image that has black lines on a white background (with some other colors here and there), as the native windows viewer will see a white background.   The file, 49MB, imports, but   The TIF image has a dark gray background instead of a white background  I can't tell why.   Any hints?  The same thing happens if I import the TIF image into georeference, which is how I discovered this in the first place.  I created/exported the TIF image using PDFCreator (from a print of a PDF to a TIF, using that program).   Within PDFCreator, I chose a TIF export that set the color map to 4096 colors, as the default created a TIF file that was twice as large.  On testing with the default size (16 million colors or some such).... That file imported and showed the background as white.  And I can't tell why, for that, either.   Any hints?  ======== In response to the comment/question by @BradHards:  The TIFFTAG_PHOTOMETRIC is not present in either file.  The gdalinfo for the large file and small file are identical, but for the presence of two extra lines on the file where the white background turns to dark gray.  Each band sets NBITS=4 for Image Structure Metadata: eg:     Band 1 Block=5100x68 Type=Byte, ColorInterp=Red   Image Structure Metadata:     NBITS=4 Band 2 Block=5100x68 Type=Byte, ColorInterp=Green   Image Structure Metadata:     NBITS=4 Band 3 Block=5100x68 Type=Byte, ColorInterp=Blue   Image Structure Metadata:     NBITS=4   Something about the NBITS=4 state turns the background dark gray.  Alternatively, there is some other problem with the PDFCreator export.  These are the full GDALInfo:  Small with dark gray background:   Driver: GTiff/GeoTIFF Files: small file.tif Size is 5100, 6600 Coordinate System is `' Metadata:   TIFFTAG_DATETIME=2015:01:28 16:41:04   TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)   TIFFTAG_SOFTWARE=GPL Ghostscript 9.07   TIFFTAG_XRESOLUTION=600   TIFFTAG_YRESOLUTION=600 Image Structure Metadata:   INTERLEAVE=PIXEL Corner Coordinates: Upper Left  (    0.0,    0.0) Lower Left  (    0.0, 6600.0) Upper Right ( 5100.0,    0.0) Lower Right ( 5100.0, 6600.0) Center      ( 2550.0, 3300.0) Band 1 Block=5100x68 Type=Byte, ColorInterp=Red   Image Structure Metadata:     NBITS=4 Band 2 Block=5100x68 Type=Byte, ColorInterp=Green   Image Structure Metadata:     NBITS=4 Band 3 Block=5100x68 Type=Byte, ColorInterp=Blue   Image Structure Metadata:     NBITS=4   Large with white background   Driver: GTiff/GeoTIFF Files: larger file.tif Size is 5100, 6600 Coordinate System is `' Metadata:   TIFFTAG_DATETIME=2015:01:28 17:07:16   TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)   TIFFTAG_SOFTWARE=GPL Ghostscript 9.07   TIFFTAG_XRESOLUTION=600   TIFFTAG_YRESOLUTION=600 Image Structure Metadata:   INTERLEAVE=PIXEL Corner Coordinates: Upper Left  (    0.0,    0.0) Lower Left  (    0.0, 6600.0) Upper Right ( 5100.0,    0.0) Lower Right ( 5100.0, 6600.0) Center      ( 2550.0, 3300.0) Band 1 Block=5100x68 Type=Byte, ColorInterp=Red Band 2 Block=5100x68 Type=Byte, ColorInterp=Green Band 3 Block=5100x68 Type=Byte, ColorInterp=Blue


Why/how does including . in PATH pose a security risk?

I was reading  to understand the inner workings of bash when I saw this:  You should never have . in your PATH as it poses a security risk, among other problems.  and couldn't figure out why this is a security risk and the answer didn't elaborate.


Suppose $p$  and $p^2+2$ are prime numbers, prove that $p^3+2$ is also a prime number. Actually I do not know what is the relationship among square numbers, cube numbers and prime numbers


split the content of a specific column with variable number of strings

I need to print each "word" in the second column in a new line, copying the text in the first column in each new line. The columns are tab separated and all "words" in the second column start with "GO:" and are separated by a blank space. Also, there are different number of "words" in each line, from one to dozens.  For example  TRINITY_DN23871_c0_g1_i1   GO:0003735 GO:0005783 GO:0005829   TRINITY_DN6318_c1_g1_i1    GO:0004707 GO:0005524   Desired output  TRINITY_DN23871_c0_g1_i1   GO:0003735 TRINITY_DN23871_c0_g1_i1   GO:0005783 TRINITY_DN23871_c0_g1_i1   GO:0005829 TRINITY_DN6318_c1_g1_i1    GO:0004707 TRINITY_DN6318_c1_g1_i1    GO:0005524   I have tried with awk   awk -v RS=" " '{print}' unique.ID_all.unique.GOs2   but what I got was  TRINITY_DN23871_c0_g1_i1 GO:0003735 GO:0005783 GO:0005829 TRINITY_DN6318_c1_g1_i1 GO:0004707 GO:0005524   and I'm out of ideas. Anybody can help?


How to allow another user in a group to read a file

I need help in this question please I have tried several times. Create a file, /home/jack/secretf7b079, containing the string secret5cd51b. Make sure the file is owned by jack. Use a group to enable cedric to also read the file, but not write to it. Make sure pedri can't access the file. The code I have used by jack user: cat > /home/jack/secret7b079 and include the string secret5cd51b. sudo adduser cedric jack, to add the user cedric to jack group. chmod 640 /home/jack/secret7b079 Thanks!


I'd like to install Vagrant software on Ubuntu 16.04, but their , only lists Debian and Cent OS. Is it possible to run this software on Ubuntu?


Swap definition of starred and non-starred command

I don't like the fact that I am required to use \abs* when I want the vertical line of the absolute value to automatically re-size. I pretty much always want it to re-size, so would like to swap the definition of the two commands, but not sure how to do that. My attempt below is commented out as it does not compile.  I can't think of a case where I'd want to use the version that does not resize, but in case some corner case arises in the future I don't want to loose that. Or, is there a good reason to not to do this swap, and  go and change all occurrences of \abs to \abs*.  \documentclass{article}  \usepackage{amsmath} \usepackage{mathtools}  \DeclarePairedDelimiter\abs{\lvert}{\rvert}  %\let\oldabs{\abs}% %\let\oldabs*{\abs*}% %\let\abs{oldabs*}% %\let\abs*{\oldabs}%  \begin{document} Not sure why this is the default behavior, but it is: \[\abs{\frac{1}{2}}\]  Would prefer to get this behavior using \textbackslash{abs}, instead of having to use \textbackslash{abs*}. \[\abs*{\frac{1}{2}}\] \end{document}


Is R's glm function useless in a big data / machine learning setting?

I am surprised that R’s glm will “break” (not converge with default setting) for the following “toy” example (binary classification with ~50k data, ~10 features), but glmnet returns results in seconds.  Am I using glm incorrectly (for example, should I set max iteration, etc.), or is R’s glm not good for big data setting? Does adding regularization make a problem easy to solve?  d=ggplot2::diamonds d$price_c=d$price>2500 d=d[,!names(d) %in% c("price")]  lg_glm_fit=glm(price_c~.,data=d,family = binomial())  library(glmnet) x=model.matrix(price_c~.,d) y=d$price_c lg_glmnet_fit=glmnet(x = x,y=y,family="binomial", alpha=0)  Warning messages: 1: glm.fit: algorithm did not converge  2: glm.fit: fitted probabilities numerically 0 or 1 occurred    EDIT: Thanks for Matthew Drury and Jake Westfall's answer. I understand the perfect separation issue which is which is already addressed.    And in my original code, I do have the third line which drops the column that derives the label.  The reason I mention about "big data" is because in many "big data" / "machine learning" settings, people may not carefully test assumptions or know if data can be perfectly separated. But glm seems to be easily broken with "unfriendly" messages, and there is not a easy way to add the regularization to fix it.


I am trying to draw a very simple network diagram. My code:       \begin{tikzpicture}     \node[draw, shape=circle] (v0) at (0,0) {$v_0$};     \node[draw, shape=circle] (v1) at (1,0) {$v_1$};     \node[rectangle,minimum width=6em,draw] (v3) at (0.5,-1) {$v_3$};     \draw [thick] (v0) -- (v1)     (v0) -- (v3)     (v1) -- (v3);     \end{tikzpicture}   This produces the following figure:   I want the lines from the upper two nodes to go straight down towards the edge of the rectangle. Is there a simple way to do this?


What is the past participle of the verb to get?

I get often confused with the verb to get in the past tenses. I see gotten, got, etc. Could someone kindly clarify with some few examples?  Shall I say:  I have got   or   I have gotten


I am confused with the input and output, can anyone tell me why I get such output.  #include<iostream> #include<stdlib.h> using namespace std;  int main() {     int ival, oddcnt(0), evencnt(0);     while (cin >> ival) {         switch (ival) {         case 1, 3, 5, 7, 9:             oddcnt++;             break;         case 2, 4, 6, 8, 10:             evencnt++;             break;         }     }     cout << "Quantity of odd number:" << oddcnt << "\n"         << "Quantity of even number:" << evencnt << endl;     system("pause");     return 0; }   This is the result I get: Input:1 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 6 6 6 7 7 7 7 8 8 9 9 10 10 10 EOF Output:Quantity of odd number:2        Quantity of even number:3


What does "node size" refer to in the Random Forest?

I do not understand exactly what is meant by node size.  I know what a decision node is, but not what node size is.


Hartshorne's proof of Proposition 2.5, Chapter II of his book Algebraic Geometry

Let $S = \sum_{n\ge 0} S_n$ be a graded commutative ring. Let $f$ be a homogeneous element of $S$ of degree $> 0$. Let $D_+(f) = \{\mathfrak{p} \in\operatorname{Proj} S\mid f \notin \mathfrak{p}\}$. Let $S_{(f)}$ be the degree $0$ part of the graded ring $S_f$, where $S_f$ is the localization with respect to the multiplicative set $\{1, f, f^2,\dots\}$. The proposition states that      $D_+(f)$ is isomorphic to Spec $S_{(f)}$ as locally ringed spaces.   Part of his proof is as follows. For $\mathfrak{p} \in D_+(f)$, let $\psi(\mathfrak{p})=\mathfrak{p}S_f\cap S_{(f)}$. Then $\psi(\mathfrak{p}) \in$ Spec $S_{(f)}$. He wrote that the properties of localization show that $\psi\colon D_+(f) \rightarrow$ Spec $S_{(f)}$ is bijective. I wonder why $\psi$ is surjective.


Why aren't all the badges shown on the track menu?

I like using the 'Track Badges' menu on my profile a lot (I know what you're going to say, I just have a knack for these things), but I keep noticing something a bit unusual.  Many of the Badges featured on the actual list do not get featured on this menu. For example, I've been hoping to be able to track progress for the Pundit badge (ten comments with score of five or more), but it doesn't show up in the menu.  Why not?


Rigid bodies: angular velocities, momentum, Inertia Tensor, rotational kinetic energy. Books suggestions?

I'm having a hard time with understanding how to model the rotational kinetic energy of rigid bodies. I will appreciate any good suggestion about resources such as books or videos regarding topics like adding angular velocity vectors (with inclined axis), and how to calculate Inertia Moments and Inertia Tensors. These are some exemples of the systems I will try to model:        Any suggestions or advice will be really helpful. Thanks in advance.


Why did the Daleks try to blow up the TARDIS?

While watching Doctor Who, I found something that troubled me. The Daleks attempted to blow up the TARDIS; but the last time we saw the TARDIS explode it took the entire universe with it. There was another moment in which the Daleks attempted to destroy the TARDIS at the Crucible. Why did the Daleks attempt to destroy the TARDIS knowing it would blow up the universe and them along with it.


Remove leading zeros before decimal in Datatables

I want to remove the number to the left side of the decimal if that digit is less than 1.  Basically, I want to remove a zero if its there.  Meaning 0.25 would become .25 but 1.50 would remain 1.50  $(document).ready(function() {   $('#mytabl').DataTable({     "searching": true,     "pageLength": 40,     "scrollX": true,     "paging": false,     "info": false,     drawCallback: () => {       const table = $('#mytabl').DataTable();       const tableData = table.rows({         search: 'applied'       }).data().toArray();       const totals = tableData.reduce((total, rowData) => {         total[0] += parseFloat(rowData[1]);         total[1] += parseFloat(rowData[2]);         return total;       }, [0, 0]);       $(table.column(1).footer()).text(totals[0]);       $(table.column(2).footer()).text(totals[1]);     }   }) });


What size should an image be for printing a very large (10m x 2m) banner

I work as a graphic designer and until know I have worked only in vector. Now I have to do a very big banner like a landscape and I have to use a photo for this. What is an acceptable resolution for an image for a 10m x 2m banner?


What’s the difference between arbitrary and random

I googled and it showed that the main meaning of “arbitrary” is “based on random choice or personal whim, rather than any reason or system”, while that of “random” is “made, done, happening, or chosen without method or conscious decision.” It seems that they have pretty the same meaning, is there any difference between them?


I was checking my old set of homework problems that I found this one:     If $G$ is a group, show that $x^2ax=a^{-1}$ has a solution if and only   if $a$ is a cube in $G$.   One direction is easy. If $a$ is a cube in $G$ then there exists $y \in G$ such that $a=y^3$. Now with direct manipulations it is shown that $x=y^{-2}$ is a solution to $x^2ax=a^{-1}$.  The other direction is harder though. I first attempted to isolate $x$ and then somehow show that it's necessary for $a$ to be a cube. But since I had no idea how to isolate $x$ I gave up. Then I decided to prove the existence of $y \in G: a=y^3$ by showing that a particular map is bijective so I can come up with a nice variable change to conclude that $a$ must be a cube, but this attempt failed as well. I'm tired now, so I think I'm giving up. I'm looking for a hint or a complete solution if a hint is not possible at this stage.


Does matter turning into energy, or vice versa, violate the Law of Conservation?

I'm new to physics. And I have curiously wondering about the relationship between matter and energy. From what I understand, one can create the other, but is it truly creating or just aiding in the process?


Possibility of adding a directory in Python-nested?

What is the best way to check if the directory a file is going to be written to exists, and if not, how to create the directory using Python? Does a flag exists as "open", that makes this happen automatically?


The only 1-manifolds are $\mathbb R$ and $S^1$

I recall having heard somewhere that the only 1-manifolds (second countable, Hausdorff, connected spaces locally homeomorphic to $\mathbb R$) are $\mathbb R$ and $S^1$. Is this true? If so, is there a reasonably elementary proof?


How to highlight in yellow a specific part of a string using jquery

I would like to know how to highlight in yellow only the plus sign (+) of a string using jQuery.   For example: Text: Lorem ipsum dolor sit amet, consectetur adipiscing elit +


Contact from wizpert.com via stackoverflow?

Well today as I was going home I got a strange email, in my private inbox (email associated with S.O.) asking me if I had solved a question on S.O. that I didn't ask. To be more precise I had given an answer.   After reading:       and several other email related issues on S.O. I decided to let you all know about this because probably I am not the only one.   So the mail subject was:     Re: Deleted facebook account - Cannot access my apps?   which refers to   And the body (masked last name of sender):      Hi Jimmy,      Just wondering if you ever got this question answered.  If not, maybe   a brief chat with a html wizpert could help: link   .      Good luck getting this resolved!      Cheers,      Michael      ------------------------- Michael W%^%^GF Founder, CEO @ Wizpert   Now I know that my email address is not visible and I read about the MD5 regarding gravatar but I don't think this is the case. I thought about some methods and sure it's possible via metadata, github, etc for someone to get my mail, but I do not dare to think that this has reached an automated level, so that some service could easily get the email of S.O. members.   I didn't get annoyed by the message, since the CEO took the time to contact me :-p but someone else could get annoyed by these kinds of messages, since they come in the important inbox of gmail.   What is more strange is that Wizpert seems to be a nice site and also is active in the Careers 2.0 if I am not mistaken.   Another thing that crossed my mind is that since Wizpert needs unanswered questions to promote their services, possibly this is an action of Wizpert trying to attract people into their services.   Well that's it, I hope I did good to let you know (maybe I did't include the correct tags).


A continuous function which does not converge to its Fourier series.

Where can I find an example (or the theorem) for a continuous function which does not converge pointwise to its Fourier series, as well as its explanation?  I would prefer a web page or a free site or an "easy" to find book.   Thanks for your help!


Are there matrices such that $AB=I$ and $BA \neq I$ ?   $A$ and $B$ are square matrices


I have the following program:  #include <opencv/cv.h> #include <opencv/highgui.h> #include <opencv2/imgproc/imgproc_c.h>  int main(int argc, char** argv) {    return 0;  }   I run the following gcc command:  gcc -std=c99 -I/shared/sav/opt/include -I/shared/sav/opt/include/opencv -I/shared/sav/opt/include/opencv2 -I/shared/sav/Downloads/openCV-2.3.1/include -L/shared/sav/opt/lib -L/shared/sav/Downloads/openCV-2.3.1/build/lib -lopencv_highgui -lopencv_imgproc -lopencv_core -lm my_program.c -o my_program   and I have the following error messages:  /tmp/cczX8weZ.o: In function `cvDecRefData': my_program.c:(.text+0xa68): undefined reference to `cvFree_' /tmp/cczX8weZ.o: In function `cvGetRow': my_program.c:(.text+0xbc0): undefined reference to `cvGetRows' ...   and other things like those above.  What is the cause of the problem and how can I solve it?


I'm learning about switches in Javascript, and whenever I add a case, I'm not sure whether to use single quotation marks or double quotation marks.  switch(answer) {     case 'hello':         console.log("Hello there!");         break; }   vs  switch(answer) {     case "hello":         console.log("Hello there!");         break; }   Note that in the line with the case, I put double quotation marks instead of single quotation marks on the second example. Which one is correct?


Heartbleed: What is it and what are options to mitigate it?

This is a  about understanding and remediating the Heartbleed security issue.   What exactly is CVE-2014-0160 AKA "Heartbleed"? What is the cause, what OSs and versions of OpenSSL are vulnerable, what are the symptoms, are there any methods to detect a successful exploit?   How can I check to see if my system is affected? How can this vulnerability be mitigated? Should I be concerned that my keys or other private data have been compromised? What other side effects should I be concerned about?


For which $n$ and $k$ are there nontrivial homomorphisms from $S_n$ to $\mathbb{Z}/k\mathbb{Z}$?

The question  got me curious and thinking about the following:   For which $n$ and $k$ are there nontrivial homomorphisms from the symmetric group $S_n$ to the cyclic group $\mathbb{Z}/k\mathbb{Z}$ of order $k$? I'm thinking it might be an open problem. Is this a problem with a known solution? If so, how can we prove it?   Thanks!


Are these adjectives interchangeable?  I always hear: 'An Arab man.' but never 'An Arabic man.' and I always hear 'Arabic coffee' but never hear 'Arab coffee.'


Here, I wanted to verify that:     The property of being characteristic is a transitive relation among subgroups of a group $G$.   For subgroups $N,H\leq G$, we have $N$ char $G$ and $H$ char $N$. So $N$ char $G$ implies: $$\forall\psi\in Aut(G); \psi(N)=N$$ $H$ char $N$, so for all elements in $Aut(N)$, $H$ is remained never changing. Especially, when I take $\psi'=\psi|_{N}$ then $\psi':N\to Aut(N)$ would be in $Aut(N)$ and $\psi'(H)=H$. Since the last equality is true for $H$ and the maps, caused by restriction on $N$, then I have $H$ char $G$.  Honestly, I am inly not satisfied form the conclusion here and think I am losing something. Thanks for your hints.


Is 10.04 LTS Still Supported by the Ubuntu Desktop Advanced?

Is  10. 04 LTS Still Supported by the Ubuntu Desktop Advanced?  If yes, until when?


We use "append" and "prepend" for adding to the end and to the beginning respectivly. Is there a word for removing in same place


If I enter anagram strings like "act" and "cat" then it gives this error: Exception in thread "main" java.lang.NullPointerException     at examples.Anagram.main(Anagram.java:20)  import java.util.Scanner;  public class Anagram {     public static void main(String[] args){         Scanner sc = new Scanner(System.in);         System.out.print("Enter the String 1:");         String str1 = sc.nextLine();         System.out.print("Enter the String 2:");         String str2 = sc.nextLine();         Boolean isAnagram = false;         Boolean[] isVisited = new Boolean[str1.length()];          if(str1.length() == str2.length()){             for(int i=0;i<str1.length();i++){                 char c = str1.charAt(i);                 isAnagram = false;                 for(int j=0;j<str2.length();j++) {                     if (c == str2.charAt(j) && !isVisited[j]) {                         isAnagram = true;                         isVisited[j] = true;                         break;                     }                     if (!isAnagram) {                         break;                     }                 }             }         }         if(isAnagram){             System.out.print("Anagram:)");         }else{             System.out.print("Not a Anagram:(");         }     } }


Windows 10 Start Menu can't have multiple shortcuts with the same target

Problem  If you create two shortcuts with the same target then only one of them is displayed in the Start Menu. This is true for:   search results within the Start menu manually browsing program folders within the Start menu pinned shortcuts within the Start menu   This is important because:   the shortcuts might have different settings defined in the Properties dialog, such as different compatibility settings, or be set to start in different directories. some programs install a shortcut to a command prompt which is set to open in the program's installation folder. This enables easy access to the program from the command line without having to modify %PATH%, but it means that users who are unaware of this "lose access" to CMD. Programs that do this:           Things I've tried   Renaming shortcuts   Only the shortcut that comes first alphabetically is displayed  Using folders doesn't help   Only the shortcut in the folder that comes first alphabetically is displayed  Pinning shortcuts doesn't help   the pinned shortcut updates to point to the displayed shortcut      Steps to reproduce  Fully up-to-date Windows 10 Home.   Start → search for "Command Prompt" (or "cmd"). (Optional) Right-click on Command Prompt → Pin to Start.   This makes Command Prompt available when you open the Start menu without searching for anything.  Right-click on Command Prompt → Open file location   This opens a File Explorer window in %APPDATA%\Microsoft\Windows\Start Menu\Programs\System Tools  Copy the Command Prompt shortcut and rename the copy "AAA Command Prompt"   This ensures it appears before Command Prompt when files are listed alphabetically.  (Optional) Right-click on the new AAA Command Prompt shortcut → Properties   Change something. (E.g. set the "Start in" directory to a different location, such as C:\)    Notice that it is now not possible to access Command Prompt from the Start menu - it has been replaced with AAA Command Prompt everywhere. If you rename AAA Command Prompt to ZZZ Command Prompt then you get back the ordinary version and lose the customised version. Moving the shortcuts to different folders within %APPDATA%\Microsoft\Windows\Start Menu\Programs\ doesn't help.    Any ideas?


Is it safe to use letters A and B for drives?

My computer (a modern one, with Windows 8.1) is equipped with a DVD drive and a SD card reader. I'm considering assigning letters A and B to DVD and card reader. I know well that those letters were reserved for floppy disk drives (I'm old enough to remember the floppy disks era), but I am 99.99% sure that I will never use floppy disk drive. Is there any rational reason not to use A and B letters for DVD and card reader then?  To be perfectly clear: I am not asking what is the story behind letters A and B - I know it already. I just want to know the consequences of assign A or B to drive that is not a real floppy drive.


What are the first/most influential works on galaxy-scale apocalypse?

It seems that planetary or galaxy-scale destruction is a common trope in science-fiction. I'm thinking of things like the halos in Halo or the Dakara weapon in Stargate, able to wipe out all lifeforms in the Galaxy in mere moments. Are there any prior works showing similar technology? I'm mainly interested in litteratures but also welcome works in other media. If so, what is the first notable work showing this concept, and what are the most influent ones?


Find users within the radius of location based on zip code

I have an app/site and need to perform a search for all users located within a user specified distance of their zip code. I have two tables, one with user data and a second with zip code information. I'm having difficulties figure out the query to find users that are within the distance.  I don't understand geospatial query needed to make it work.  User Table Structure  username        zip  =====================    tester55        60608    Tester1         00544    iosuser1        73120    Tester3         01002   Zipcodes Table Structure  zip     latitude     longitude ------------------------------ 00501   40.8154      -73.0451 00544   40.8154      -73.0451 01001   42.0702      -72.6227 01002   42.3671      -72.4646   I want to use the zip code of a user to find other users within a certain radius.  Here are the queries I have so far, I'm trying to figure out how to make it one query.  First Query      Select users.zip, users.username, zipcodes.zip as user zip,  zipcodes.longitude as userlong, zipcodes.latitude as userlat from users, zipcodes where users.zip = zipcodes.zip AND username = 'tester55   Second Query  SELECT zipcodes.zip, zipcodes.city, zipcodes.state, zipcodes.longitude, zipcodes.latitude, ( 3959 * acos( cos( radians(userlat) ) * cos( radians( zipcodes.latitude ) )      * cos( radians( zipcodes.longitude ) - radians(userlong) ) + sin( radians(userlat) ) * sin(radians(zipcodes.latitude)) ) ) AS distance  FROM zipcodes HAVING distance < 50 ORDER BY distance   Any help is greatly appreciated.


Prove convergence of sequence defined recursively $a_{n+1} = \sqrt{6+a_n}$

We have a sequence: $$a_1=\sqrt{6}$$ $$a_{n+1} = \sqrt{6+a_n}$$  The problem is to check convergence and then find the limit. We know that sequence converges when it is monotonic and bounded. With a little trying I can guess, that this sequence must be bounded by 3 and it's monotonic. Then I can prove my guess:  Proving upper boundary I guessed $a_n<3$:   For $a_1 = \sqrt{6} < 3$ $a_{n+1}= \sqrt{6+a_n}$ $a_{n+1} = \sqrt{6+3} = 3$   However, I personally don't like this proof. It requires guessing and checking if I was right.  Later I could use this and prove monotonicity, but I'd like to ask you for some better proofs you may know.


Can nginx location blocks match a URL query string?

Can   match a URL query string?  For example, what location block might match HTTP GET request  GET /git/sample-repository/info/refs?service=git-receive-pack HTTP/1.1


It is well known that the ring of formal power series over a field $K[[x_1,x_2,\ldots,x_n]]$ is an UFD. My question is the following: the ring $K[[x_1,\ldots,x_n]][x_1^{-1},\ldots,x_n^{-1}]$ is also UFD? I was not able to find any reference on such a result.


Why there is no Syncing Mechanism for Editing posts?

It happened many times that I submit an Edit Suggestion and immediately after that I see the post has already been edited by another guy (usually higher-rep) and my edit has been rejected by either Community or reviewers.  Why there is no mechanism to prevent simultaneous edits and avoid unfair rejection?   This is my first attempt to edit the post:   As you can see it got rejected by community because another user submitted an edit. And immediately after that I wanted to re-edit my edit which turned to this (Actually it rolled back all the edits):


How do I set exposure with a manual flash?

I recently got an old Canon AE-1 film camera back in working order. I'd like to use my modern 430EXII Speedlight flash with it, however since there is no TTL metering, I have no idea how much the flash will affect the exposure of my shot (note that I have confirmed that the AE-1 will trigger the flash). I'd rather not discover that my shots were either blown out or way to dark after going through several rolls of film.  Are there any basic rules-of-thumb or basic calculations for anticipating how much a burst from the 430EXII will affect the exposure of a subject at various distances?


Why not just ram the Borg with unmanned ships?

In "The Best of Both Worlds, Part 2", when it seems all is lost, as a last resort, Riker decides he is going to ram the Borg at maximum warp in a bid to stop them reaching Earth, which would of course destroy the Enterprise.  We never find out if it would have worked, and yes it was an act of despair, but the question remains: why did Starfleet not just use unmanned ships as weapons, or even just strap a huge ship-sized missile to a warp drive?


Proof of a double summation reduction identity

I'd like to see a proof of this identity I discovered:  $$ \sum_{i=1}^{n}\sum_{j=1}^{i}a_j = \sum_{i=1}^{n}a_i(n-i+1) $$  Probably there's something I forgot because I couldn't manage it.  [edit]Possibly with just identities, not examples please!  [edit2]No induction procedure, either.


Wifi disconnects abruptly and frequently

Wifi disables abruptly. Tried the solution available on the internet.None worked.Need to disable and enable wifi to start the connection. Cant upgrade to Ubuntu 18.04 as download stops due to wifi issue.Need help.   output after running lspci command:  $ lspci -knn | grep -i net -A3 02:00.1 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 12)          Subsystem: ASUSTeK Computer Inc. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [1043:200f]          Kernel driver in use: r8169          Kernel modules: r8169  03:00.0 Network controller [0280]: Ralink corp. RT3290 Wireless 802.11n 1T/1R PCIe [1814:3290]          Subsystem: Foxconn International, Inc. RT3290 Wireless 802.11n 1T/1R PCIe [105b:e055]          Kernel driver in use: rt2800pci          Kernel modules: rt2800pci


Prove that $\gcd(a, b) = 1 ⇒ \gcd(a^2, b^2) = 1$

I have a question from a sample exam I find difficults to solve:  Prove that if $\gcd(a, b) = 1 ⇒ \gcd(a^2, b^2) = 1$ .  I don't have any idea how to start. I'd like to get helped. thanks!


Can two voltmeters connected to the same terminals show different values? Circuit with induced EMF

The circuit shown below consists of two resistors connected in series that form a closed loop. No electrical sources are in that loop.Let’s assume that the resistance of the wires that connect the resistors and form the loop is zero.Inside the loop is an external changing magnetic field that induces inside that loop a constant EMF of 1 V.   The current inside the loop is calculated using Ohm’s Law :  The problem was introduced by former MIT professor Walter Lewin. The problem was introduced in this video (starting at 35th min of the video):  In the video is shown that two voltmeters connected to the same terminals show different values. Can two voltmeters connected to the same terminals show different values? My solution to this problem would be: To measure the voltage between points D and A, the circuit has to be divided into two halves, the left half of the loop and the right half of the loop. If the induced EMF is considered to be equally distributed through the loop then in every half of the loop there is an induced EMF of 0.5 V:  The polarity of the the induced EMFs is according to Lenz law.  The voltage between points D and A by writing the equation trough the left half of the loop is:  The voltage between points D and A by writing the equation trough the right half of the loop is:  The conclusion is that there is a unique voltage value between points D and A, and the measured value should be 0.4 V. Now let’s connect to the circuit between points D and A two voltmeters. The two connected voltmeters together with the wires that connect them to the main circuit form a second loop. Let’s assume that the resistance of the wire that connects the voltmeters and forms the second loop is zero. The left half of the second loop is connected to the voltmeter between points C and B, the right half of the second loop is connected to the voltmeter between points F and E. There is also an induced EMF of 1V inside the second loop. If the induced EMF is considered to be equally distributed through the second loop then the final circuit can be represented with the model shown on below.  The voltage between points C and B is defined with the following equations:  The voltage between points F and E is defined with the following equations:  The calculations above match the measurement performed by professor Walter Lewin. My main question is : What is the theoretical potential difference between points D and A?


CentOS 6 how to clear machine ID for a template?

I want to create a template from CentOS 6 so that each VM feels like a unique install. I found sys-unconfig which works but I don't like that it asks for a new password on boot. What alternatives are there?


Use raw json in Command attribute (/setblock)

So, I'm making a machine in a minecraft server that detects if someone is holding a cake named Flying Cake and then make them be able to fly. It was working perfectly, until I realized plugin's commands can't use selectors. This is a problem because the /fly command cannot detect which player to toggle flight.  So far I have this command: execute if entity @a[distance=..10,nbt={SelectedItem:{id:"minecraft:cake",tag:{display:{Name:"\"Flying Cake\""}}}}]  And this one: setblock ~2 ~ ~ command_block{Command:""}  What I'm trying to do is make the second command block set the next command block to /fly (player) enable. To do that, you need to get raw JSON in the {Command:""}. I will be using: [{"text":"fly "},{"selector":"@a[distance=..10,nbt={SelectedItem:{id:"minecraft:cake",tag:{display:{Name:"\"Flying Cake\""}}}}]"},{"text":" enable"}]  Is this possible?


Does the flight itinerary provided for Schengen visa strict the country of entry?

I already have a Schengen visa. Initially my plan was to spend the whole period in the country already applied for -Spain-, and my flight itinerary was inbound and outbound from Spain accordingly.  Due to some changes in plan, my point of entry seems to have to change to Germany instead (where I will spend about 5 nights), then I will make my way down to Spain (staying for around 30 days) until I leave back home.  Would that be acceptable, or is it in anyway penalized?  Please note, the question isn't about being penalized for entering from a country other than which issued the Visa, but rather to not-follow/change the itinerary plans already submitted under which the Schengen Visa was initially granted.     I have already emailed the embassy about the change in plans and awaiting the reply (24-48 hours), but it would great to get an insight   from fellow travelers.


I'm a new blender user so i may make mistakes from here and there sometimes, but I have this problem where this weird dotted box is on my interface window and it's starting to annoy me.   I'm not sure how to fix it, and everytime i press shift+z it's like a window for rendering your scene.  So again, i'm not sure how it got there or how to get rid of it. If anyone can tell me how to get rid of it, that would be great. Thanks!


Is the topologist's sine curve a manifold?

I'm studying about manifolds. I'm an engineer and want to grasp the concept of manifold without too deep dive into rigorous mathematics. My question is whethere the "topologist's sine curve" defined as $S = \{(0, y) : y \in (-1,1)\} \cup \{(x, \sin (1/x)) : x \in (0, 2/\pi)\}$ can be a manifold. I tried to find some explnations in books and web. However, what I found are all about (path/local) connectedness. I'm not familiar with topology and not want to study it extensively. So I tried to understand the question with very minimal knowledge.  As far as I understand, to say that a set is a manifold, I need to set a topology (open subsets) on the set. As a subset of $\mathbb{R}^2$, every open set in $S$ should have a form $S \cap A$ for an open set $A \in \mathbb{R}^2$. Any interval in the vertical axis part of $S$, e.g. $I = \{(0, y) : 0 < y < 1/2\}$, cannot be an open set in $S$. It is because every open set in $\mathbb{R}^2$ containing $I$ also contains some other part of $S$ : there is no way to express $I$ in the form of $S \cap A$ where $A$ is open in $\mathbb{R}^2$. Then there is no homeomorphism from an open subset of $S$ containing $I$ to an open set in $\mathbb{R}$. It is because, if there is one, the preimage of an open interval in $\mathbb{R}$, to which $I$ is mapped, must be open but $I$ is not open. So there cannot be a coordinate chart for $I$ and $S$ is not a manifold. This is what I understand. My first question is whether or not this understanding is correct.  The second question is whether $S$ can be a manifold if I give a different topology. I cannot express precisly how to define the topology but intuitively the sine function part is homeomorphic to an open interval in the real line and the vertical part is also homeomorphic to an open interval in the real line, if I consider $S$ as a space of its own, not a subspace of $\mathbb{R}^2$. Is this true? If true, how can I express the topology precisley?    This question is not a duplicate of . I read it. However, the concept of connectedness confuses me. As I said in the first paragraph, I want to understand my question with minimal knowledge on topology such as just the definition of open sets, continuous functions and manifolds. Moreover the linked question does not concern my second question.


Should I use a hyphen in the term "in(-)situ visualization"?

The term in(-)situ visualization denotes a visualization or graphics that is depicted in place, for instance, a  that is embedded into text.  As the dictionaries tell, the adjective or adverb in situ is written as two words. But for concatenated terms in scientific language, oftentimes, in-situ (with a hyphen) is placed in front of the main noun. Searching for the term in Google and Google Scholar, I find both alternatives about equally frequent. Also, the  lists both versions for related terms such as in(-)situ burning.  What is the correct spelling of in(-)situ visualization? Is there a specific rule that applies?


Recover content from a deleted user and assign ownership to other user

There is a user that needs to be deleted but I need to keep his content. I want to know if there's a way to transfer the ownership of all of his content (nodes, userpoints, etc.) to another user? I tried , but there is no option there.  I know that I can delete the user and keep the content and give it to the Drupal anonymous user, but it´s possible to set up an specific user?


Electronic Devices and airport security checks

I have seen recently that the US and UK have announced that all 'electronic devices' will have to be 'powered up' before allowing them on board a plane, I believe for the UK it's on all flights though I am not sure about the US.  Starting next month I am going to doing a fair amount of travelling overseas and I am concerned about some particular items I will be carrying like an external HDD, Apple TV, Apple wifi router and a mini PC (similar size to the Apple TV).  These devices don't have a battery and so can't be 'powered up', even if they are plugged in to the mains without a screen or keyboard you wouldn't really be able to tell they were actually 'on'.  I have tried to find out what the 'rules' are but they seem intentionally vague, does anyone have experience of carrying similar devices recently and know whether there might be a problem with the above.   I don't really want to end up at the airport facing losing a lot of expensive equipment and valuable data or missing the flight.


How to join all objects created in a Python script?

I have a script that creates a bunch of objects and at the end joins all the objects in the scene into one big object using this piece of code: bpy.context.view_layer.objects.active = bpy.data.objects["Base"] bpy.ops.object.select_all(action="SELECT") bpy.ops.object.join()  This works fine if I start with an empty scene, and then copy the final object into my main scene. However, I would like to have a script that creates a new object in the main scene, so I need a way to join all the objects created with the script, and not the ones already in the scene. I thought of adding some unique prefix to all the created objects, then selecting all the objects with that prefix, join them, and finally remove the prefix from the final object, but that solution seems very tedious and wrong. How would you solve this?


Files from mounted volume cannot be send to trash, only deleted permanently

I use Ubuntu 18.04.3 on the laptop with two logical volumes. When I select some file on the home volume and press "Del", it goes to Trash. On the mounted volume when I press "Del" it is removed permanently. If I do the right click on the file I also see only "Delete permanently" option.  It did not work like this before, and I am not sure what changed, because I think that I did not install any updates in the time period when the behavior changed.  The folder ".Trash-1000" on the mounted volume still exists.  Any idea how to turn on the "Delete to trash" option again?  UPD: About the size of the file: I am experimenting now with a 5 kb txt file.


Why does Ubuntu offer an old version of GNS3 instead of the latest one?

I notice that GNS3 v0.8.7-2 was installed on Ubuntu via sudo apt install gns3 instead of the new version which is  as this question is asked.  May I know why Ubuntu still using the old version of GNS3 in it's repository?  user@linux:~$ sudo apt show gns3 Package: gns3 Version: 0.8.7-2 Priority: optional Section: multiverse/net Origin: Ubuntu Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com> Original-Maintainer: Daniel Lintott <daniel@serverb.co.uk> Bugs: https://bugs.launchpad.net/ubuntu/+filebug Installed-Size: 22.7 MB Depends: ucf, python:any (>= 2.7.5-5~), dynamips (>= 0.2.8), python-qt4 (>= 4.5), xdotool, xterm Recommends: wireshark Homepage: http://www.gns3.net/ Download-Size: 3,219 kB APT-Sources: http://my.archive.ubuntu.com/ubuntu bionic/multiverse amd64 Packages Description: Graphical Network Simulator  GNS3 is a graphical network simulator that allows simulation of  complex networks and to launch simulations on them. It is an excellent  complementary tool to real labs for administrators of Cisco networks  or people wanting to pass their CCNA, CCNP, CCIP or CCIE certifications.  It can also be used to experiment with features of Cisco IOS or to check  configurations that need to be deployed later on real routers.  .  You may configure devices ranging from Cisco routers, Cisco PIX firewalls,  Cisco ASA Firewalls, Cisco IDS to JunOS routers using Qemu or Pemu. GNS3  uses dynamips as an emulation back end, an IOS emulator which allows users  to run IOS binary images from Cisco Systems.  .  Cisco IOS, PIX, ASA or JunOS software images are not included.  user@linux:~$    I know I can get the latest version by updating the repo and install it as follows.  sudo add-apt-repository ppa:gns3/ppa sudo apt-get update sudo apt-get install gns3-gui   I just want to know why Ubuntu didn't use the latest version of GNS3 by default?


If $f(x)$ is a real valued $C^2$ function on the real line such that its value is between $-1$ and $1$. Then, if $f(0)^2+f'(0)^2=4$, I have to show that there exists $x_0$ on the real line such that $f(x_0)+f''(x_0)=0$. I think I have to use a very ingenious maximum-minimum theorem for $g(x)=f(x)^2+f'(x)^2$ but I am just stuck.... I cannot find a way to solve this problem....Could anyone please help me? It's so frustrating...


Real line $\mathbb R^1$ with the countable complement topology is not compact

The real line with the countable complement topology is not compact.  I create an open cover of $\mathbb R$ by: Let $\mathbb Q$ denote the rationals. Let an open cover be defined be the set of $\mathbb Q-\{q\} $, where $q \in \mathbb Q$. Then this set is countable. I am unsure how to proceed from here. And is this a good example of an open cover that doesn't have a finite subcover? Which will lead to my conclusion of not compact?


I've just made a bootable usb on windows7, and now I want to replace my windows7 with Ubuntu. When I choose the option replace windows 7 with Ubuntu, I need to select a drive. Since I have only one drive in my desktop, I must use it. But on my windows the drive is partitioned into a C  and D drive (both 500GB). I put all my files on the D drive, so I can still use them in Ubuntu. My intention is to install Ubuntu on the c drive from windows, but when i click on advanced partitioning tool, I see that there are four partitions:  sda1(ntfs): 14.7 GB, sda2(ntfs): 104.9 MB, sda3(ntfs): 492.7 GB, sda4(ntfs): 492.7 GB   My problem is that I don't really know what the first two partitions are, and which one is the c:/ drive from windows. I guess it is the third, but I must be sure because otherwise all my data is lost. What exactly do I have to do to just install Ubuntu on one partition and keep another partition with my files (the d in windows)? Also I don't really know on what type of filesystem Ubuntu has to be installed on(fat, ntfs, ext,..). The desktop that I'm working on is a Acer Aspire AX3900. Thanks (and sorry for my bad English).


Need help why here have java.lang.NullPointerException

Why here have  Exception  in thread "Thread-0" at unsynch.Bank.transfer(Bank.java:30)     at unsynch.UnsynchBankTest.lambda$0(UnsynchBankTest.java:22)     at java.lang.Thread.run(Unknown Source) Thread[Thread-3,5,main]Exception in thread "Thread-2" java.lang.NullPointerException   Code:  public void transfer(int from, int to, double amount) throws InterruptedException {     bankLock.lock();     try     {         if(accounts[from] < amount)              sufficientFunds.await();    //当前条件不符合。被阻塞，放弃锁         System.out.print(Thread.currentThread());         accounts[from] -= amount;         System.out.printf("%10.2f from %d to %d", amount, from, to);         accounts[to] += amount;         System.out.printf(" Total Balance: %10.2f%n",getTotalBalance());         sufficientFunds.signal();  //通知阻塞线程激活。     }     finally     {         bankLock.unlock();     } }


Looking for count down clock in CEWP using html/jquery

I am looking to insert a count down clock in content editor web part using html / jQuery. Did any one ever do this? I am unable to figure out how to start as am not a pro in scripting.


Appending a dictionary of dictionaries with another dictionary of dictionaries not getting order correct

I have 4 python dictionaries where the value of each key is another dictionary: a={'a': {'e': 4}} b={'b': {'f': 5}} c={'c': {'g': 6}} d={'d': {'h': 7}}  I want to merge dictionaries a, b, c and d together so that I have one final dictionary that looks like: {'a': {'e': 4}, 'b': {'f': 5}, 'c': {'g': 6}, 'd': {'h': 7}}  where the order of the parent dictionary is in the order in which I add each original dictionary. So I created an empty dictionary and did this: x={} #create empty dictionary x.update(a) #update with first dictionary print x x.update(b) #update with second dictionary print x x.update(c) #update with third dictionary print x x.update(d) #update with forth dictionary print x  The result is this: {'a': {'e': 4}} {'a': {'e': 4}, 'b': {'f': 5}} {'a': {'e': 4}, 'c': {'g': 6}, 'b': {'f': 5}} {'a': {'e': 4}, 'c': {'g': 6}, 'b': {'f': 5}, 'd': {'h': 7}}  I am not sure why, after the third update, that c is added to x between a and b. And then after the forth update, d somehow gets added at the end. It seems random. Keep in mind, that sorted will not work. The above is an example of what I want and my keys may not always be in alphabetical order. I simple want the order in which I added each dictionary. Edit: This is for python 2.7, but appreciate answers for 3.6 as I will be migrating a tool from 2 to 3 in the near future.


Why am I getting java.lang.NullPointerExeption error?

I'm trying to write a program that converts images to grayscale and then saves copies of the images with a new name ("gray-" + fname), but I'm getting error message java.lang.NullPointerExeption when I run the program.   The  gray.save();   line at the bottom of the below code gets highlighted. I'm not sure why the program says the variable gray is null. Should I change the order of the lines? Thanks for your help.  import edu.duke.*; import java.io.File;     public class ImageConverterAndSaver {         public ImageResource makeGray(ImageResource inImage) {         ImageResource outImage = new ImageResource(inImage.getWidth(), inImage.getHeight());         for (Pixel px:outImage.pixels()){             Pixel inPixel = inImage.getPixel(px.getX(), px.getY());             int grayConversion = (inPixel.getRed() + inPixel.getGreen() + inPixel.getBlue()/3);             px.setRed(grayConversion);             px.setGreen(grayConversion);             px.setBlue(grayConversion);         }         return outImage;     }         public void doSave(){         DirectoryResource dr = new DirectoryResource();         for (File f: dr.selectedFiles()) {             ImageResource image = new ImageResource(f);              String fname = image.getFileName();             String newName = "gray-" + fname;             image.setFileName(newName);             ImageResource gray = makeGray(image);             gray.draw();             gray.save();         }     }     }


Installing Linux on hard disk that will be used by another computer with different hardware

I was given a laptop with a totally dead display. I do not want to pay to replace the broken display, but I would like to use the laptop as a server and connect to it via SSH to control it.  I have pulled out the internal hard drive from the broken laptop, and I want to install Debian GNU/Linux and the SSH server onto this HDD using a working Debian laptop.  However, the hardware in the two laptops is very different, and I am wondering what kind of problems I would run into when I plugged the drive back in to the laptop with the broken display because of this?  How would I make this work? What is the proper way for me to install a bootable copy of Linux onto a HDD that will be used by a computer with different hardware?


I am working on a ASP.NET  project with SQL as back end.(This SQL server is provisioned in cloud using Azure) Part  of my Project, I need to store lot of PDF file (like invoices, Customer Updates) etc. The Number of these PDF files are expected to big in number (5TB may be) Now that I provisioned my SQL server in Azure, I am looking best practices On Where I can store the files?  Can I use Azure Blob? Is it cheaper? or storing in SQL server itself is better (I know backup is a concern) Or any other suggestion?


Does the Shape Water cantrip work on snow or ice?

The spell description specifically says you can freeze water, but it doesn't mention unfreezing/thawing water that was already frozen or if frozen water counts as water.  Can I use Shape Water to either:   Apply any of the standard effects to an equivalent volume of ice without thawing it? or;    Thaw an equivalent volume of ice (assuming the effect lasts for an hour then the water freezes again).   This question is specifically about using the spell to effect ice. My party is about to head into snowy mountain region and I want to know if I can use it whilst there.


How do I not be a war spectator, but be able to battle in clan wars?

I have never been in a clan war before. I've tried, but it doesn't let me. How do I not be a spectator? I want to be in a war. Thank you!!


I am trying to find values of $r>0$ such that $\lim\limits_{n\rightarrow \infty} \sum\limits_{k=1}^{n^2}\frac{n^{r-1}}{n^r+k^r}$ is finite. I have tried to use integral methods for this limit such as $\sum\limits_{k=1}^{n^2}\frac{n^{r-1}}{n^r+k^r}=\sum\limits_{k=1}^{n}\frac{n^{r-1}}{n^r+k^r}+\sum\limits_{k=n}^{n^2}\frac{n^{r-1}}{n^r+k^r} = \frac1n\sum\limits_{k=1}^{n}\frac{1}{1+(\frac kn)^r}+\sum\limits_{k=n}^{n^2}\frac{n^{r-1}}{n^r+k^r}$. So the first term, I could use the integral method to estimate. However, the second one is hard to evaluate. Could you please help me with this? Thanks


How to digitize an image graph to excel data?

I'm trying to compare my model results with an experiment. I want to overlap the model curve with experiment curve from a paper.   What are my options for digitizing the graph from an image in the pdf paper to excel data?


How to install ATI graphics card drivers?

AMD 's website is not opening.So how shall I install my ATI graphics card driver?


How do I make the speed of an animated object constant instead of accelerating?

I am relatively new to Blender and am looking for help with my animation. I know all about keyframing but my question is how to make the speed of an object constant when it moves between 2 keyframes, instead of it starting slow, going quickest in the middle, and slowing at the end.


I know that a flat adverb is an adverb that has the same form as its related adjective, but does that mean any adverb without the -ly suffix is grammatically correct? For instance, if I said I am “extreme angry,” is that the same as saying I am “extremely angry”? Or is saying that it is “dangerous hot outside” the same as saying it is “dangerously hot outside”? I realize that flat adverbs are less common than they used to be, but that doesn’t change the question: Are flat adverbs always formed from words, namely adjectives, missing the -ly suffix?  Thank you  PS:  is what prompted my question:     “Flat adverbs used to be much more common than they are today. For example, in Robinson Crusoe, Daniel Defoe writes of weather that is "violent hot." Samuel Pepys wrote in his famous diary of being "horrid angry." But most of these adverbs have long since been abandoned.”   Bolded words are my emphasis.


Standard charger for Macbook Pro insufficient

I recently bought a MacBook Pro (15-inch, 2018) and I am using the OOTB Power Adaptor (87W) and USB-C cable.  I am finding that when I run computationally expensive processes (e.g. I utilize multiple cores for data analysis), that the laptop will discharge (albeit at a slower pace) even when plugged in. This is obviously problematic if I have a continuous process, that is meant to last multiple hours.  This laptop is an upgrade from a 2015 MacBook Pro, with the Magsafe 2 Power Adaptor, on which I never experienced this problem.  Is there a solution to this? Perhaps an upgrade to the Power Adaptor (I think 87W is the max Apple provides) or the USB C Cable? Or is there something else?


Rename command not found when running a script

I'm trying to to execute a script, which uses the command rename.   When I execute it, I get a message rename: command not found. Any ideas?   if [[ -z '$3' ]]; then     shopt -s dotglob     rename "$EXPRESSION" ./* else     rename "$EXPRESSION" "$3" fi


how can i display the latest items from another site collection

I have a web application, with three site collections . and i want inside my team site to be able to display the latest pages that  have been added to my enterprise wiki site collection. so what are the available approaches which i can follow?  Thanks in advance for any help.  Regards


Contacts don't appear in contact book, but they appear in 'To' field. Why?

When creating a new email in Microsoft Outlook 2007 all the contact's I've ever contacted appear as they should in the 'To' field when I start to type.   The problem I'm having is I need to save them to an Excel sheet but I don't want to go through each one and type them out manually so I was going to export my address book. When I looked in the contact's section there weren't any contacts there.  How do I access the contacts that are showing up in the 'To' field?


Multisite: List all Blogs alphabetically

Right now I do this …
     <?php          $blog_list = wp_get_sites();         foreach ($blog_list AS $blog) {             global $blog_id;             $currentblog = get_blog_details( $blog['blog_id'] );             echo "blogname . "'>".$currentblog->blogname."";         }     ?>
   Is it possible to list all Blogs alphabetically. How would I do that?


Can you get more pc boxes in pokemon y/x?

Can you get more pc boxes In pokemon x and y?


Is it possible that black holes might devour all masses of the universe?

I am only an interested layman in cosmology and GR. In recent years, we have learned that black holes indeed exist in the universe and that almost all galaxies contain massive black holes in their centers. Black holes, in essence only devour other (stellar) matter and they also swallow each other as has been demonstrated by the gravitational wave discoveries. Is it possible that black holes eventually will "eat" most or even all normal and dark matter of the universe? And could this, and a merging of black holes, lead to a situation where all the universe ends up being a few or even only one black hole?


I found this explanation:   but what about present?  I continue to work or I continue working? Are they the same?


Topological spaces in which a set is the support of a continuous function iff it is the closure of a open set.

An exercise of Rudin's Real and Complex Analysis says:     Is it true that every compact subset of $\mathbf{R}^1$ is the support of a continuous function? If not, can you describe the class of all compact sets in $\mathbf{R}^1$ which are supports of continuous functions? Is your description valid in other topological spaces?   I proved that, in every metric space, a set (not necessarily compact) $A$ is the support of a continuous function if and only if it is the closure of an open set.  However, I don't think that this characterization holds for every topological space.  So, in order to find a counter-example, I tried to use the discrete and the trivial topologies. However, the discrete topology is metrizable and this characterization holds for topological spaces with the trivial topology.  Is this result true for any topological space? If not, what would be a counter-example?