Angular Momentum of a rigid, extended object: When we see a rotating object, is the state of rotation is totally relative?

Angular momentum of an object is a physical quantity that depends on the chosen point about which to calculate the angular momentum. It is often said that an object that has been thrown up in the air and is rotating, is physically rotating about the center of mass. I don't think that is what is physically happening. We chose the center of mass as the point of rotation because it is convenient mathematically (it makes the separation of translation and rotational energy easier). We could choose any other point (inside, outside the object, in motion or at rest relative to the object) and calculate the rotation about that arbitrary point. It is not a physical fact that the free object rotates about the center of mass. Even an object that is constrained to rotate about a fixed axis, we could describe the rotation about any point, not necessarily points on the fixed, constrained axis.


Finding an isomorphism between $\mathbb{Z}[i]/(7)$ and $\mathbb{Z}[\sqrt{-2}]/(7)$

I was having some trouble finding an explicit isomorphism between $\mathbb{Z}[i]/(7)$ and $\mathbb{Z}[\sqrt{-2}]/(7)$.  $\textbf{What I have noticed is}:$   7 is a prime element in $\mathbb{Z}[i]$ so $(7)$ is a maximal ideal in $\mathbb{Z}[i]$ and $\mathbb{Z}[i]/(7)$ is  a field.  7 is also a prime element in $\mathbb{Z}[\sqrt{-2}]$   $\textbf{What I have been trying to do is this}$   Find a surjective homomorphism between $\mathbb{Z}[i]/(7) \rightarrow \mathbb{Z}[\sqrt{-2}]/(7)$. Since $\mathbb{Z}[i]/(7)$ was a field, the kernel of this homomorphism will be either the whole ring or just $0$. In the latter case it would be a isomorphism.    I am having trouble finding this surjective homomorphism:  I have noticed that $\bar{{i}}^{2}=-1$ so the image of $\bar{{i}}$ must be sent to something whose square is $-1$. Any help would be appreciated. I may be missing some obvious insight.


Could you please suggest a good book on statics and dynamics. The portions I have to cover include   Statics : Equilibrium in 2&3 dimensions, Virtual work,Common catenary etc  Dynamics : Rectilinear motion,SHM,Work and energy,Work and energy,Central orbits


Why do video game framerates need to be so much higher than TV and cinema framerates?

It seems that video games need to have something like 60 frames per second in order to be smooth and realistic. But TV and films only have about 24 or 25. Why the difference?


Which is the best software to create 3D mockup from scratch?

I am always get stuck when I have to create a specific position/view/custom mockup. I want to design the mockup very realistic like the image. I can't find any options to create such mockup but I am curious how covervault.com creates the mockup which software does he uses? Thank you guys!


Prove or disprove that $\forall k \in {{\Bbb Z}^ + }:k \geqslant 5,{\text{ }}{6^k} + 1$ is composite.

How can I show this? I was doing some proves, and this question came out of nowhere, but I felt curious about this and so I tried this. The question is that given any $k \in {{\Bbb Z}^ + }$ such that $k \geqslant 5$, show that ${6^k} + 1$ is composite. This question looks and feels extremely difficult to prove for me, and so I want help from this. Luckily, I did some proves such as using By Induction, By Contradiction, and more, and nothing worked. Also, I tried looking this problem through the Internet, and nothing... What I tried to do was the following, though: Show that if $$A = \{ {6^k} + 1|{6^k} + 1{\text{ is prime}}\} $$then $A = \{ 7,37,1297\} $. Especially, only when $k = 1$, $k = 2$ or $k = 4$, ${6^k} + 1$ is prime. Or equavilently, ${6^k} + 1$ is prime iff $k = 1$, $k = 2$ or $k = 4$. Any ideas? Thanks, Joshua. Update: This question is already answered. Thanks, everyone for helping. Update 2: I think that I can prove this (but not completely). Proof: Let $k \in {{\Bbb Z}^ + }$ and odd. Then $k = 2m + 1,m \geqslant 2$. $\Rightarrow {6^k} + 1 = {6^{2m + 1}} + 1 = 6 \cdot {36^m} + 1$. Since $36 \equiv 1(\bmod 7) \Rightarrow 6 \cdot {36^m} + 1 \equiv 6 \cdot {1^m} + 1 = 6 \cdot 1 + 1 = 7 \equiv 0(\bmod 7)$. Hence when k is odd, $6^k + 1$ is composite. If $k = ab$ and $b$ is odd, then $6^k + 1 = 6^{ab} + 1 = 6^{ab} + 1 \Rightarrow 6^a + 1|(6^{ab}+1)$.


My first section title clashes with my header, but does not for any subsequent section titles. How can I fix this?      %Preamble \documentclass[british]{report} \usepackage[utf8]{inputenc} \usepackage[a4paper,left=25mm, right=25mm,top=25mm,bottom=25mm]{geometry} %Formats page \usepackage{babel} \usepackage{graphicx} %Allows images \graphicspath{ {images/} } %Sets image folder location \usepackage[useregional,showdow]{datetime2} %Allows dynamically updating date \usepackage{fancyhdr,lastpage} %Headers and Footers \pagestyle{fancy} \fancyhead[C]{     \title{XXX: Xxxx 12 Xxxxxxxxx Xxxxxxxxxxx - Xxxxxxxxx 1}\\ \author{Xxxx Xxxx Xxxxxx Xxxxx}\\     XXX: 12345678 $\vert$ XXX: 12345678} \fancyfoot[C]{$\thepage$ of $\pageref{LastPage}$}  \fancypagestyle{empty}{\renewcommand{\headrulewidth}{0pt}\fancyhead{} \fancyfoot[C]{$\thepage$ of $\pageref{LastPage}$}}    %Document Information \title{XXX: Xxxx 12 Xxxxxxxxx Xxxxxxxxxxx - Xxxxxxxxx 1} \author{Xxxx Xxxx Xxxxxx Xxxxx}   %Document Content \begin{document} \maketitle  \section*{Question 1} \setcounter{page}{2}   \pagebreak \section*{Question 2}  \pagebreak \section*{Question 3}  \pagebreak  \end{document}


Is the possessive of a name that ends in 's' pronounced differently if it refers to a group of people (like a band) instead of a single person?

How do you think names that have the plural "s" should be pronounced when they get the apostrophe? I researched this on the web and I couldn't find any very reliable results. For example, how should these three words be pronounced?  The Beatles'  Red Hot Chili Peppers'  Mr. Jingles'   Context: In case you don't know, The Beatles are a band, Red Hot Chili Peppers are also a band. "Jingles" is a last name that includes the plural "s". It is not a band name. I know that normally, when a plural word gets the apostrophe, you don't make a second /ɪs/ or /ɪz/ sound. For example, you don't say, /ɡɑɪzɪz/ when you say  "guys' ". But I think we might pronounce another /ɪs/ or /ɪz/ when we say the words I gave because names like "The Beatles" represent one singular band while they also represent the people in the band. When you say "Mr. Jingles" also it represents one person. So I thought it may be correct to pronounce the example words I gave as, "The Beatles + /ɪz/", "Red Hot Chili Peppers + /ɪz/", "Jingles + /ɪz/".


What is the equivalent to "ByRef" in Java?

I'm working on translating some code from VisualBasic to Java and I've encountered a snag when using the ByRef keyword in VB. That doesn't exist in Java!  How should I simulate a ByRef call in Java?  Edit: Just to clarify for those who don't know VB, ByRef identifies a variable in the parenthesis after calling a function and makes it so that when that variable is changes inside of the function, it will also change higher up where it is called as opposed to ByVal where only the value of the variable is remembered. Changing a ByVal variable in the method will not affect the variable where it is called.


What is the best way to clear all controls on a form C#?

I do remember seeing someone ask something along these lines a while ago but I did a search and couldn't find anything.   I'm trying to come up with the cleanest way to clear all the controls on a form back to their defaults (e.g., clear textboxes, uncheck checkboxes).  How would you go about this?


In the Euclidean Ring ${\Bbb Z}_3[x]$, what is the remainder of the euclidean division of $x^4+2x^3+x^2+2x+2$ by $x^2+2$?

So far I've $(x^2+2)(x^2+2x-1)+4-2x$   but the options for the remainder are: $2x+1$, $2x$, $x+1$, or $x$.


How to keep Alt+Shift from inadvertently opening the menu bar of the current app on Windows (or how to make ALT purely a modifier key)

I'm a long-time Linux user, and a non-native speaker. Just like in Windows, Linux supports the Alt+Shift keyboard combination to switch between input languages. However, its behavior is more forgiving if you mistype and press Alt, followed by Shift, without overlap. On Linux (and  OSX), this results in nothing. On Windows, it detects the lone "Alt" key being pressed, and activates the menu bar of whatever app you're running.  On Windows, this is especially unnerving in a chat application like Skype, when you are frequently switching between languages, and you may not immediately see that you mistyped, Windows selected the menu for you, and the next characters you're typing actually open up some weird menu, or log you out, or inadvertently start a video call. So it's a pet peeve, but it's driving me crazy.  In short, the question boils down to how do you make Left Alt in Windows to behave purely as a modifier key (without triggering any action if it is pressed all by itself)?  AutoHotKey or AutoIt hackery is okay. However  solution doesn't really work, since it breaks most Alt+something shortcuts.


Coupon Collector's Problem with X amount of coupons already collected.

I am having an issue with understanding how to calculate a specific case of the Coupon Collector's Problem. Say I have a set of 198 coupons. I learned how to find the estimated amount of draws to see all 198 coupons, using the following equation:  $$n \sum_{k=1}^n\frac1k$$  It turns out that for $n = 198$, the expected number of draws is approximately 1162. Let's assume, however, that I already have some of the coupons, say 50. How should I go about solving the same problem, given that I've already collected $X$ of them?


I've got on Stack Overflow a couple of questions I made, which I'm now able to respond myself. I would like to update them just for future reference. But I don't find how to do it.   I suppose is a reputation limit (I've got 140 points) but I'm not finding the required level. Can anyone tell me what are the requirements?   EDIT:   My question:   SOLVED: I see my questions were edited and now I see the button. I'm doubting myself but I think it was back to life because of the edit. Thanks :)


Remove "In" from bibliography in biblatex with apa-styple

I try to remove "In" word from the bibliography with APA-style. I found some comments suggest me to use the renewbibmacro, but it still appears in the bibliography. This is my sample code \documentclass{article} \usepackage[utf8]{inputenc}  \title{TExtTemp} \author{mynameisbee } \date{November 2020}    \usepackage[ backend=biber, bibencoding=utf8, style=apa6, citestyle=numeric, firstinits=true, isbn=false, doi=false, url=false, sorting=none, clearlang=true, natbib=true, intitle=true, date=year, uniquelist=false, maxbibnames=6, maxcitenames=1, defernumbers=true ]{biblatex}  %% for a list number index \makeatletter \RequireBibliographyStyle{numeric} \makeatother    \DeclareFieldFormat[inproceedings]{title}{\textbf{#1}} \DeclareFieldFormat[inproceedings]{booktitle}{#1} \DeclareFieldFormat[article]{title}{#1} \DeclareFieldFormat[article]{journaltitle}{\textbf{#1}} \DeclareFieldFormat[article,unpublished,misc]{volume}{\textbf{#1}}  %% remove comma in Author name %\DeclareNameAlias{default}{last-first} \renewcommand*{\revsdnamepunct}{} %remove "in" out from proceeding \renewbibmacro*{in:}{}    \begin{filecontents}{jobname.bib} @article{Ellen,   title={Pathogen-Host Interactions: Antigenic Variation V. Somatic Adaptations},   journaltitle = {Journal of Signal Processing Systems},   author={Hsu, Ellen and Du Pasquier, Louis},   volume={57},   year={2015},   publisher={Springer} }  @inproceedings{Pisit,    title = {Latent Cognizance: {{What}} Machine Really Learns},   booktitle = {{{ACM}} International Conference Proceeding Series},   author = {Nakjai, Pisit and Ponsawat, Jiradej and Katanyukul, Tatpong},   date = {2019},   pages = {164--170} } \end{filecontents}  \addbibresource{jobname.bib}  \begin{document}  \cite{Ellen} is a chapter in \cite{Pisit}.  \printbibliography[title=REFERENCES] \end{document}  This is my result. In the red block, "In" word is still appear. Another question, I want to remove the bracket (green block). How can I remove it? Thank you for all suggestions. I am sorry for my language.


Is it always necessary to use definite article before superlative?

Normally we use definite article when we want to talk about something known or specific, but I noticed that always people used to put a definite article before superlatives even when they are talking about something generally.   For example:      "The best quality of gold can be found in the most of the   countries".   and I'm wondering what's wrong for example with:      Best quality of gold can be found in most of countries   ?  Is it always necessary to use definite article before superlatives? No exceptions? If there are examples for not using definite articles when using superlatives I'd like to know about them.   For example, can I say I am happiest. He is fastest. She is friendliest. without using definite article?


how to pass variables between 2 bash scripts (export doesn't work)

here are 2 example scripts: script.sh: #!/bin/bash export TEST=1  script2.sh: #!/bin/bash ./script.sh echo $TEST  script.sh is supposed to assign 1 to the TEST variable and script2.sh is supposed to run script.sh to assign 1 to the TEST variable and then print the value of the TEST variable (1). that doesn't work for some reason. there is no output, and if I run script.sh and then run echo $TEST it won't print anything - the variable is empty or nonexistent. any idea why/how to do that properly? thanks in advance!


Best Azure Service for Large no of SQLServer Databases

We have a dedicated SQL Server Machine for a SAAS application with about 200+ databases, the server has E5-2620 with 64 GB RAM, Now we want to move all the databases to the Azure, so for looking into the options we can either go with a Virtual Machine like (DS13 v2) which can support all these DBs or can use the Azure SQL Elastic Pools like Standard with 400 eDTUs.  My Question is that in the Long Run and from management and scalability point of view which option is better, and also will the Standard Elastic Pool with 400 eDTU's can provide the same performance as the Virtual Machine?  One of the major concerns for us is the performance of the SQL DBs in Azure, as this is one of the reason to move the whole application to the Azure so that in the future as the no of users grow we can easily upgrade our instances to cater the increased load.


Can a single PS Plus subscription be used on two different profiles on the same PS4?

Both my girlfriend and I play on the PS4 at home, so there are 2 profiles on PS4. When we set our profile in PS4, we set the console as the primary console.  Now we want to buy PSN Plus subscription, and I want to know if the same subscription can be used in both profiles, or  only in one.   In case the same subscription can be used in both profiles, how can we set it up? Or is automatic?


Vertical-align: middle doesn't work in CSS

I have one container div 'full-h' named with 100vh min-height.  Inside that I have a 'content' div with unknown height.   Inside content div I have 2 items with unknown height.  I'm trying to centering this two item vertically on desktop for 100vh min-height. If the height of the content is higher than the screen height on mobile devices, I want the height to be determined automatically according to the content. So I used min-height instead of height.   I have tried many different methods as a result of my research on the internet for hours. I tried to use flexbox and table content. But whatever I do it doesn't work. I thought that the problem might be related to my computer and I restarted my browser and computer. I've run my code on JSFiddle. But the result is the same. Many thanks to all of you in advance.  Here is JSFiddle:   Here is the code:  HTML    body {   margin: 0;   padding: 0; }  .full-h {   min-height: 100vh;   background-color: #666; }  .v-center {   display: table; }  .content {   display: table-cell;   vertical-align: middle;   background-color: #999; }

Hello World!

Lorem ipsum dolor sit amet, consectetur adipisicing elit. Quaerat, quidem. Expedita, aperiam, molestiae sequi necessitatibus, natus dolorum enim laborum incidunt praesentium itaque a. Nobis sint nisi accusamus omnis, est perspiciatis.


Empirical Distribution: problem from "All of Statistics"

I'm working through this textbook, and here is a problem I'm stuck on. Setting: We are given an unknown distribution $F$, observed independent  data points $X_1, ..., X_n \sim F$, the empirical distribution function $\hat F_n$, and two values $a,b \in \mathbb{R}_+$. Tasks:  use the central limit theorem to find the limiting distribution of $\hat F_n(a)$ find a term for the value of $\text{Cov}(\hat F_n(a), \hat F_n(b))$  My thoughts: The central limit theorem only tells me something about the sample mean, which doesn't meaningfully restrict specific points on the CDF. Even if I knew $\mathbb E(F)$ exactly, there are still an uncountably infinite number of possible values of $F(a)$. So the application doesn't seem trivial. My idea was to define a new sequence of random variables $A_1, ..., A_n$ where $A_i := 1_{X_i \le a}$. Now, we have $A_i \sim \text{Bernoulli}(p)$, where $p = F(a)$ is unknown. The sample mean $\overline{A_n}$ will converge to $F(a)$ by the weak law of large numbers. Now, I can apply the Central Limit Theorem to the $A_i$ and obtain that $\overline{A_n} \rightsquigarrow Z$ where $Z \sim N(p, p(1-p)/n)$. So, it appears that $N(p, p(1-p)/n)$ may be the solution to the first problem. However, the second task made me doubt whether this is right. Since $\text{Cov}(X,Y) = \mathbb E(XY) - \mathbb E(X) \mathbb E(Y)$, I would have to compute $\mathbb E(\overline{A_n}\overline{B_n})$ (with $\overline{A_n}$ as above and $\overline{B_n}$ analogously for point $b$) somehow, and I have no idea how to do this.


Proving that there exists a solution to the quadratic equation

Let $n\in\mathbb{Z}_{>0}$. Prove that there exist $x,y,z\in\mathbb{Z}_2$ (2-adic integers) such that $x^2+y^2+z^2=n$ if and only if $n$ is not of the form $4^m(8k+1)$ with $k,m\in\mathbb{Z}_{>0}$.  I suppose this problem has to do with the Hasse principle. However, in class we only saw results for quadratic equations in two variables. Does there exist an efficient way to solve this type of problem?


Prove that $\int_0^\infty\frac1{t^x+1}dt = \frac\pi x \csc \frac\pi x$

I'm stuck on this identity: $$ \int_0^\infty\frac1{t^x+1}dt = \frac\pi x \csc \frac\pi x $$ Could someone show me a proof for this? What I've tried: I've thrown a bunch of substitutions and integration by parts at this, but they haven't led me to the answer. I did, however, find these identites: $$ \int_0^\infty\frac1{t^x+1}dt = \int_0^\infty\frac{t^{x-2}}{t^x+1}dt = \int_0^1\left( \frac{1-t}t \right)^{1/x}dt $$ But none of these seem to lead anywhere helpful. I also tried introducing another variable to turn it into something similar to the Laplace Transform, but I'm not very familiar with methods like that, so they've led nowhere.


Prove that $\sqrt 2 +\sqrt 3$ is irrational.

Please prove that $\sqrt 2 + \sqrt 3$ is irrational.  One of the proofs I've seen goes:     If $\sqrt 2 +\sqrt 3$ is rational, then consider $(\sqrt 3 +\sqrt 2)(\sqrt 3 -\sqrt 2)=1$, which implies that $\sqrt 3 − \sqrt 2$ is rational. Hence, $\sqrt 3$ would be rational. It is impossible. So $\sqrt 2 +\sqrt 3$ is irrational.   Now how do we know that if $\sqrt 3 -\sqrt 2$ is rational, then $\sqrt 3$ should be rational?  Thank you.


Nginx - Redirect a bunch of domains to a single domain, with SSL

Nothing insidious going on but I've got a bunch of domains that we've bought for a service and I don't want to buy an SSL certificate for them all (there's about 11).  As an example, we've got:  example.com thisisexample.com ourexample.com theexample.com   I have an SSL certificate for example.com and it is the main domain we're going to use. To protect our IP we've bought up a lot of similar domains and we're redirecting them all to example.com.  I've setup some redirects already and they're working fine on HTTP/80, both www and non-www.  However, accessing any of the domains on HTTPS/443 shows the privacy error.  Is there any way around this without having to buy lots of certificates? Can I not redirect https for one domain to another and allow that to terminate SSL?  EDIT:  My question is relating to Nginx, not Apache2.


I have a question in real analysis!  If $K$ is compact metric space, show that there is a countable dense subset $E$ of $K$  How can i prove it?  Could you help me for the idea or proof?


what is the meaning of RMSE in caret::train

I'm confused by the exercise solutions of the book Applied Predictive Modeling.  In   at the beginning of page 4  Resampling results   RMSE   Rsquared  RMSE SD  Rsquared SD   1.382  0.8716    1.014    0.08729 The RMSE is slightly more than 1.4%   To my knowledge RMSE isn't a % (of what?) It's  mse <- mean(residuals(fit)^2) rmse <- sqrt(mse)   Can someone help me on this?


Where to download older Blender versions? Namely Blender 2.80

Where to download Blender 2.80?  I downloaded Blender 2.82a but it always crashes. So I'd like to try 2.80 but I can't find it on the official Blender site.


What is safest way to install 20.04 with Windows 10

I've done this before on my machines, but this one belongs to my wife! I usually have success, but sometimes it turns in to a time consuming nightmare. EDIT How about this for safety?  Buy new small drive Install Linux OS with only new drive connected Run this way to get accustomed Connect both drives and modify Windows boot manager to point to new drive as a secondary choice. /EDIT  Computer is ACER desktop ATC-605-UB11 HD has only one partition large enough for an OS. I tried running MINT from the USB stick and it worked great. Also would like GRUB to default to Windows at least in the beginning. Should I use windows partition tool or Ubuntu. Thanks! Stan


Problem about continuous functions and the intermediate value theorem

Let $S^{1} := \lbrace(\cos\alpha, \sin\alpha) \subset \mathbb{R}^{2} | \alpha \in \mathbb{R}\rbrace$ be the circumference of radius $1$ and $f: S^{1} \to \mathbb{R}$ a continuous function. Prove that there exist two points diametrically opposed at which $f$ assumes the same value.  My idea for the solution: Define $\varphi: S^{1} \to \mathbb{R}$ as$$\varphi(\cos\alpha, \sin\alpha) = f(\cos\alpha, \sin\alpha) - f(-\cos\alpha, -\sin\alpha).$$ If $f(\cos\alpha, \sin\alpha) = f(-\cos\alpha, -\sin\alpha)$ for all $\alpha \in \mathbb{R}$, the result follows. Otherwise, there exist $\alpha_{1},\alpha_{2}$ such that $$f(\cos\alpha_{1}, \sin\alpha_{1}) - f(-\cos\alpha_{1}, -\sin\alpha_{1}) > 0$$ and $$f(\cos\alpha_{2}, \sin\alpha_{2}) - f(-\cos\alpha_{2}, -\sin\alpha_{2}) < 0.$$ Applying the intermediate value theorem, we prove the result. Is this a correct idea? I appreciate your commentd. Thanks!


I have troubles proving the next result:     \begin{equation} \limsup\sqrt[n]{n|a_{n}|}=\limsup\sqrt[n]{|a_{n}|} \end{equation}   where $a_{n}$ is a bounded sequence.   My attempt: Since $\limsup(s_{n}t_{n})\leq\limsup(s_{n})\limsup(t_{n})$ and $\lim\limits_{n\rightarrow\infty}\sqrt[n]{n}=1$ I have the inequality $\fbox{$\leq$}$. But I can't prove the other inequality.  I will appreciate any hint, thanks.


The most efficient way to pay off loans/credit?

Supposed you have a fixed amount of money to commit every month to debt repayment... well above all minimum payment requirements.  All other quirks and conditions being equal.  The only differences are the interest rates and the balances.  That said, Ive frequently seen it written that the best way to pay off your debts is to pay minimums on all but the highest interest rate loan, where you dump any surplus money. But I am wondering if this is necessarily the optimum way of doing it?!?! Doesnt it make more sense to pay off whichever loan is accruing the most in interest every month in terms of dollar amount? Not percentage.  i.e. the product between balance and interest rate.  Or am I wrong about this?


Proving $\sin\frac\pi7 \cdot \sin\frac{2 \pi}{7}\cdot\sin\frac{3 \pi}{7} = \frac{\sqrt7}{8}$

Prove    $$\sin\frac\pi7 \cdot \sin\frac{2 \pi}{7}\cdot\sin\frac{3 \pi}{7} = \frac{\sqrt7}{8}$$   I tried using the product to sum identities but those got me nowhere. Any help would be great.


Why are gender pronouns conventionally written as subject/object?

When gender pronouns are explicitly stated they tend to be given in the form "subject-pronoun/object-pronoun" e.g. he/him, she/her, they/them. Where does this convention originate from? Is there a particular reason why two forms are stated rather than just the subject-pronoun?


Consider a photon is an energetic particle and therefore has a gravitational field. When a photon passes a molecule or particle of dust in space it will pull the dust towards it and deform the dust. This will lose energy in the normal Newtonian way, and the energy is supplied by the photon.   Assuming that the speed of light is constant this implies that the photon will become less energetic and therefore red-shift over its travels, simply as a consequence of interactions with near objects. Is the effect real and/or measurable?


I want to speed up my system. How can i use crontab to automate the deletion of unnecessary files and cache ? In what other ways can i speed up my system ? I have disabled most of the startup applications to boot my system faster.


Is the saturation current different for different base current in CE configuration of a transistor?

I've been reading my school textbook and found out that a Transistor can act in 3 different modes i.e. active mode, saturation mode and cut-off mode (let's just for now ignore the reverse-active mode). The cut-off mode is the mode when no current flows through the base if I am right (I am talking about the C-E config). The saturation mode is when all the current provided by the external cell flows through the Transistor.  So what actually is the active mode. Also is the value of saturation current different for different values of base current?


our project basically involves reading files about the premier league and returning 1. outcomes of games played, 2. fixtures yet to be played and 3. the leaderboard(table). I'm displaying a menu in the command line and also taking in the user input from there. I'm using a while loop to match the userinput with what output to display but I wanted to say if they don't enter 1,2 or 3 that there's an error and to display the menu again and ask them to enter another input. However now if I do enter 1,2 or 3, it doesn't display my results I can't get out of the while loop. Can anyone help me? This is my code!  while(userInput == false)     {         Scanner input = new Scanner(System.in);         String pattern = "[1-3]{1}";         String userChoice;         System.out.println(menuOptions);         userChoice = input.nextLine();         if(userChoice == "1")         {             System.out.print(outcomesResults);             userInput = true;         }         if(userChoice == "2")         {             System.out.print(fixturesResults);             userInput = true;         }         if(userChoice == "3")         {             System.out.print(leaderboardResults);             userInput = true;         }         else if(!userChoice.matches(pattern))         {             System.out.println();             System.out.println("Error: unidentified selection. Please choose 1,2 or 3");             userInput = false;         }     }


JavaScript - Call a function by a string

This question is already existing in a different way, but my code is mostly different so I dont get the solution out of the other answers. That's a example Code:  http://jsfiddle.net/e52n28xs/   I want start the function like this:  var test1 = {     start: function() { } }; var fn = 'test1'; fn.start();   I know the following works, but I need the string option.  test1.start();   Maybe that's impossible?


Keeping track of bibliography references for an entire research group

This is a related question to my previous one about .   Given the relatively large number of papers that are out there, it's inadvisable to force every student to start from ground zero in building up a reference library. To me, this suggests that there should be some centralized ways of keeping track of bibliography references.   The low-cost but high-maintenance route to me would be to have an SVN repository to which people can update their own personal bibliography files. Are there other more time-efficient routes to manage this process when:   people have different computing platforms and workflows (Windows with Office, OS X with iWork, Linux with TeX, etc.)? working with collaborators at other institutes?  it's important (according to university/workplace regulations) not to have data stored "in the cloud"?


I have an equation like this:  \begin{equation} \begin{split} |a+bi|=\sqrt{a^2+b^2}\\  |a+bi|^2=a^2+b^2\\ |a+bi|^2=(a+bi)(a+bi)\\         =(a+bi)(a-bi)\\         =a^2+b^2i^2\\         =a^2+b^2 \end{split} \end{equation}   the resualt looks like this:    How can I align this equation, that all of = symbols to be under each other


Word for the behavior of people who complain at everything you do

I usually tend to see the behavior in which someone takes an action, and people criticize, and even suggest what they should have done, yet when they take that same suggestion people still criticize.  For instance: I'm slim; when I eat with my family, everyone exclaims at the amount of food I'm eating. When I eat normally, they ask "Don't you know, you should eat more so you can grow better?" When I don't eat, the same shouting takes place. So in other words, is there a word I could use to describe them or their behavior in this regard?


I have a brand new latest model of an iPod touch. Is there any way to import music videos or tv shows into it, that i've downloaded over the internet with/without iTunes? I can't figure out this iTunes thing. It doesn't seem to let me import videos from my hard disk. Wants me to connect to some iStore or something.


Convert newline-delimited list with spaces into arguments

I'm trying to write a script that I can run from the context menu in Caja (a clone of Nautilus). Its purpose is to pass the files that are selected in the file manager to a given program (for example, 7zip). A list of selected files is provided in the system variable $CAJA_SCRIPT_SELECTED_FILE_PATHS, separated by newlines. I want to pass each line of this variable to the program as an argument, even if they contain spaces.  After failing at quote-wrapping, I tried the following line:  echo "$CAJA_SCRIPT_SELECTED_FILE_PATHS" | xargs -d "\n" 7z a archive.7z   While it worked for 7zip, I changed the script so that the arguments are passed to a program I wrote and something went wrong, so I want a way to execute this in a terminal to get output from the program. I was using xterm -hold -e, but I haven't been able to make a command with a pipe in it execute this way because the shell will try to pipe output from xterm. I also tried shell redirection (by adding > log.txt to the end of the line), and it made a file for 7zip's usual output but a blank file for my program, which outputs messages just fine in the terminal.  Finally, I want a POSIX-compliant (or otherwise standard) solution so that it will work the same way on BSD and Linux.  EDIT: To clarify, I want to change some thing like this:  /path/with/a space /another/path   Into what I would hypothetically get from something like this:  char *argv[]={"/path/with/a space", "/another/path"};   EDIT2: That's how it should be in the program recieving the arguments, not the shell!


How to use a web page that requires Flash player 11.6?

I want to visit a web page that requires Flash player 11.6, but I aslo visit the page of download of , and they tell us.     Note: Flash Player 11.2 is the last supported Flash Player version for Linux. Adobe will continue to provide security updates.   Does anybody know a way to visit a website with this restrictions?


Method invocation 'getInt' may produce 'java.lan.NullPointerException'

I am a beginner and i wan to know what is 'java.lan.NullPointerException' and how to fixe this error?   Method invocation 'getInt'  may produc 'java.lan.NullPointerException'


Let $K_1 \supset K_2 \supset... $ be a sequence of connected compact subsets of $ \Bbb R^2 $. Is $ K = \cap_{i=1}^\infty K_i $ is connected?

I have managed to write down two proofs showing the connectedness of $K$. But still shaky about both of them. Here are the proofs:  1)Suppose $K$ is disconnected. Then we write it's separation as $ K = U \cup V $. Hence $ K $ is open since U and V are open.  Now, since each $K_i$ is compact in $\Bbb R^2$, hence by Heine-Borel  theorem it is closed and bounded. Hence $K$ is also closed and bounded and non-empty.  We have got that $K$ is open as well as closed. But the only open and closed sets in $\Bbb R^2$ are ${\emptyset}$ and the whole $\Bbb R^2$. But because $K$ is non-empty and bounded, hence it is not one of them. Hence our assumption was wrong. Hence K must be connected.  another proof I thought was like this:  2)Let $f : K_1 \to \{0,1\} $ be a continuous function. Then it's constant by connectedness of $K_1$ . Say $f(K_1)=0$. Then restricting the function to K, we get that $f(K)=0$.  Can any other proof be given? are these proofs valid?


partitioning of a set with kn members into k subsets such that each subset has n members

we know that $S(n,k)$ is the number of ways we can partition a set with $n$ members to $k$ subsets ( each subset has at least one member). imagine we have a set with $k*n$ members. we want to partition this set to $k$ subsets such that each of them has $n$ members. how many ways can we do this ?


Winforms: Single instance instead of multiple per run of exe on notify icon type of app without main form shown in taskbar

I would like to know if there is a way for me to determine if the existing process can be launch or open instead of creating a new instance if I click the exe application of my winforms. Currently I only have a checker if there is an existing process with the same name but I'm not familiar with opening an existing exe application. Note: I do not have main form that shows in taskbar Note: my system is running in background and only show a system tray icon


I logged into a CentOS box today to find the following"  There were 11126 failed login attempts since the last successful login. Last login: Tue Mar 10 14:36:47 2015 from X.X.X.X   Thats 11 THOUSAND login attempts in the last 3 days. WTF? Please note that this is a brand new IP I got from my provider and the box is brand new. I've yet to publish anything off of this box.  Why would I be getting such a large number of login attempts? Is it some kind of IP / Port scan?  There are essentially 4 culprits, 2 from China (MOVEINTERNET-NETWORK), 1 from Hong Kong (HEETHAI-HK) and 1 from Verizon (Verizon Online LLC (VRIS)).  This is only happening on SSH. No issues on HTTP. Should I Null route the culprit subnets? What do you guys suggest?


How old do I have to be to take a loan, and how should I go about the process?

I'm currently 16 and have been invited to attend a National Youth Conference for National Security in Washington DC this upcoming fall. I just moved in with my mom and this trip isn't exactly ideal for us financially. My mom said I was more than welcome to go on the trip as long as I came up with the money. I could make the money over the summer but the enrollment deadline is June 24. I've made a Go Fund Me page but I don't think that will help in time. I'm not sure how old I must be to take out a loan or anything about the process. Any help/advice is appreciated in this situation


how to send email through SP hosted app without using SP.Utilities.EmailProperties

i want to send email using SharePoint hosted app  to receiver(not only share point user),i followed  but it is allowed me to send mail to only SharePoint users,and when am trying to send mail to some one who is not a SharePoint user then am getting the error at  _api/SP.Utilities.Utility.SendEmail by saying bad request     (Failed to load resource: the server responded with a status of 400   (Bad Request))   is there any way to send email through SP-Hosted App without using SP.Utilities.EmailProperties?


Is there a way to tell ping to show its usual termination statistics without stopping the execution?  For instance, I'd like to quickly view:  --- 8.8.8.8 ping statistics --- 2410 packets transmitted, 2274 received, +27 errors, 5% packet loss, time 2412839ms rtt min/avg/max/mdev = 26.103/48.917/639.493/52.093 ms, pipe 3   without having to stop the program, thus losing the accumulated data.


Default value for an attribute of type Object

I am trying to default Site_Name__c for an attribute "SEComp" from other attribute.  It is giving compilation error as Cannot mix expression and literal string in attribute value, try rewriting like {!'foo' + v.bar}  It appears I am getting stuck defaulting from other attribute but default just works fine if I say 'Site_Name__c': 'Abc'  What is the right way of defaulting for this?  <aura:component implements="force:appHostable,flexipage:availableForAllPageTypes,force:hasSObjectName" controller="KF_CompanyLookupController"> <ltng:require styles="/resource/SLDS231/assets/styles/salesforce-lightning-design-system.css"/> <aura:handler name="init" value="{!this}" action="{!c.doInit}"/> <aura:attribute name="SEComp" type="Searcher_Express_Company__c"                 default="{'sobjectType' : 'Searcher_Express_Company__c',                            'Site_Name__c': {!v.defaultSite.siteName}}"/> <aura:attribute name="defaultSite" type="KF_CompanyLookupController.Site"/>    helper class  getUserSite : function(component){         var action = component.get("c.getdefaultSite");         action.setCallback(this,function(response){             var state = response.getState();             if (state === "SUCCESS") {                 component.set("v.defaultSite",response.getReturnValue());             }             else if (state === "ERROR") {                 var errors = response.getError();                 if (errors) {                     if (errors[0] && errors[0].message) {                         console.log("Error message: " +                                  errors[0].message);                     }                 } else {                     console.log("Unknown error");                 }             }         });         $A.enqueueAction(action); }   Apex controller  public class Site {     @AuraEnabled     public String siteName {get;set;}     @AuraEnabled     public String siteID {get;set;}     public Site (){       this.siteName = siteName;       this.siteID   = siteID;     } }     @AuraEnabled public static Site getdefaultSite(){     Site dSite = new Site();     User currentUser = [select Division, Country, Office__c from User where id = :UserInfo.getUserId()];     system.debug('currentUser - Division: ' + currentUser.Division + ' Country: ' + currentUser.Country + ' Office__c: ' + currentUser.Office__c);     if (currentUser.Division == 'Futurestep') {         // 1. check to see if user is FS       dSite.siteID = '50';       dSite.siteName = 'Futurestep';     } else if (currentUser.Country == 'United States' || currentUser.Country == 'Canada' || currentUser.Country == 'Brazil') {     // 2. check to see if user is in NA       dSite.siteID = '0';       dSite.siteName = 'North America';     } else {       String userOffice = currentUser.Office__c;       if (!String.isEmpty(userOffice)) {         List<Business_Rule_Processor__c> defaultSites = [Select Site_Name__c,Site_Id__c from Business_Rule_Processor__c                                                           where RecordType.Name = 'Default Site'                                                           AND Type__c = 'Default Site'                                                           AND Active__c = true                                                           AND Office__c includes (:userOffice)];         if (defaultSites.size() > 0) {           string defaultSiteName = defaultSites[0].Site_Name__c;           String defaultSiteId = defaultSites[0].Site_Id__c;           if (!String.isEmpty(defaultSiteName)) {             dSite.siteName = defaultSiteName;             dSite.siteID = defaultSiteId;           }         }       }     }   System.debug('dSite value is'+dSite);   return dSite; }


How can I return an array of objects in java?

Following is what I have done so far, but I get an exception every time I run it: class Student{     int sNo; }  public class Array {     public static Student[] createObj() {         Student[] s = new Student[10];         for(int i = 0; i<10;i++) {             s[i].sNo = i+1;         }         return s;     }     public static void main(String[] args) {         Student student[] = createObj();         for(int i = 0; i<10;i++) {             System.out.print(student[i].sNo);         }     } }  This is the exception: Exception in thread "main" java.lang.NullPointerException     at Array.createObj(Array.java:9)     at Array.main(Array.java:14)


Using egrep to find matches in a file while piping output from a cat command

I am using cat to output 6 lines of text from a text file called wordlist.txt. I am piping it to egrep and want to find matches in a second file called 8compdic.txt  command I am using is given below:  cat wordlist.txt | egrep - 8compdic.txt | less   Am getting output which has all the lines in *compdic.txt


Normal operator $\Rightarrow$ S invariant implies $S^\perp$ invariant

Here is a question as phrased in Advanced Linear Algebra (Steven Roman):     Show that a linear operator $\tau$ on a finite-dimensional complex inner product space $V$ is normal if and only if whenever $S$ is an invariant subspace under $\tau$, so is $S^\perp$.   I'm only interested in the $\Rightarrow$ direction. Wikipedia (and ProofWiki)  that uses some kind of computation with the trace. Linear Algebra Done Right chooses an orthonormal basis and then uses the fact that $\Vert \tau v \Vert = \Vert \tau^* v \Vert$.  However, the above  proofs seem a bit too computational to me. Can the following argument work?  (Use $\odot$ for orthogonal direct sum.) Suppose that $\tau$ is normal and write $$V=E_{\lambda_1} \odot \cdots \odot E_{\lambda_k}$$ where the $E_{\lambda_i}$ are the eigenspaces of $\tau$. If $S$ is a $\tau$-invariant subspace then $\tau|_S$ is diagonalizable, so $$S=\widetilde{E}_{\lambda_1} \odot\cdots\odot \widetilde{E}_{\lambda_k}$$ where the $\widetilde{E}_{\lambda_i} \le E_{\lambda_i}$ are the eigenspaces of $\tau|_S$ (which could be trivial). Then choose orthogonal complements $D_i$ such that $E_{\lambda_i} = \widetilde{E}_{\lambda_i} \odot D_i$, and then $$S^\perp = D_1 \odot\cdots\odot D_k.$$ Since each $D_i$ is a subspace of an eigenspace, they are all $\tau$-invariant.


Ubuntu and windows bootable usb partition type

So i want to create 2 bootable usb sticks: one for windows 7 and one for ubuntu 14.04. I want to boot those usb's in UEFI mode, both having 64bit ISO's, and install the two OS's in UEFI mode dual boot. (different story-different question). I have found that i must use a FAT32 or a FAT16 format for the usb.  So i go to disk utility (using master boot record) => edit partition. But there's so many partition type options.  My questions are:    Do i use FAT16 or FAT32? If we take FAT16 for example, what option should i choose between the following:    FAT16 <32M (0x04) Hidden FAT16 <32M (0x14) FAT16 (0x06) Hidden FAT16 (0x16) w95 FAT16 (LBA) (0x0e) Hidden w95 FAT16 (LBA) (0x1e) EFI (FAT -12/16/32)    Thanks a lot for the upcoming support!


installing numpy for python 3.1.2 on Ubuntu 10.04

I have installed numpy for python 2.6.5. I want to use it for python 3.1.2 and I don't know how to install it. I'm new to ubuntu and I don't know how to install it from  file. I am using Geany for programing in python3.  If I managed to installed it from there would it work in Geany?


What is the minimum charging current for NCR18650 li ion battery?

I need a rechargeable battery pack for my project, I need to know what is the minimum charging current for NCR18650 li-ion battery?  In the datasheet, it says max charge current is 2A. what is the minimum charge current?  I use tp4056 module for charging, I can change the charging current   is 300mA to 600mA ok for charge current? will it damage the battery or affect badly for a battery lifetime?  Delaying in charging time is not a problem for my application .


I was looking at my Impact rating on Arqade earlier, and I noticed that it had reached 945K.  Excited, I waited a few hours to see if it was climbing at a steady rate, only to find it had gone back down to 944K.   I don't have a screenshot to prove this, but I'm almost certain that it was 945K earlier.  I know this is a new metric for SE, but is it possible for it to go down over time?  It says it's based on upvotes and question views, but neither of those went down between the time I saw the 945K and the time it went back to 944k.


Minor vote-to-close bug when one voter is promoted to moderator

Check out ; my name appears twice. I voted to close before made moderator pro tempore, and again afterwards, and my name appears in the list twice because of that. It's a very minor bug which admittedly will happen pretty rarely, but it should at least be on the bug report list.


Can somebody help me to evaluate $$\lim_{(x,y,z) \rightarrow (0,0,0)} \frac{xy+4yz^2+5xz^2}{x^2+y^2+z^4}?$$ The first thing I tried to do was set $x=y=0$ and evaluate the limit, and I got that the limit of the function was $0$. I did the same thing for $x=z=0$ and $y=z=0$. So, I was pretty confident the limit was $0$. My online homework said that was incorrect. I think set $x=y$, set $z=0$ and took the limit, which was $\frac{1}{2}$. So basically, I found a direction in which to take the limit that didn't agree with the other directions. Can somebody tell me more about how I should think about this? How would I know to set $x=y$ in the future? I felt like it was a lucky guess. Thanks!


I am importing a mesh into blender to modify some parts before I use it with babylonjs. What I am trying to achieve is to move all of the triangles from the selected (shown in the image below) to a seperate sub-mesh for each of the triangle.    The reason i want to do this is because using babylonjs I need to visualise a color change where if color is selected for a square, all of the others around it will have the same color base that fades out more the further the square is.


Python matches the part after a .* at its last occurance

Im trying to read the server states from the guildwars API. For that i match the servername, then comes an occasional language specifier and a ",\n which i intend to match with .* and after that follows the population. But instead of directly matching the first occurrence of population it instead matches the last one. Can someone tell me why( and how to fix this)?  Edit: I found a workaround. By substituting .* with .{,20} it works.  relevant part of the API "name": "Riverside [DE]", "population": "Full"   with urlopen('https://api.guildwars2.com/v2/worlds?ids=all') as api: s = api.read() s = s.decode('utf-8') search = re.search(r'''Riverside.*"population": "''',s,re.S) print(search) s = s[search.span()[1]:] state = re.search(r'[a-zA-Z]*',s) print(state)


Calling a winform control method from a separate thread

I'm writing a plugin that interacts with a winform map control that can display shapefile layers.  I have a timer that will start a background worker to make changes to the displayed shapefile layer.  Once the shapefile gets updated I call a method that's part of the shapefile layer object to refresh the the layer displayed on the map.  When I call the method it initiates a bunch of other events and methods that's part of the map control.  I continually get a Cross-Thread error when the the refresh is called.  Any suggestions how I could accomplish this?  Should I be looking at using something else besides a backgroundworker?


How to iterate over arguments in a Bash script

I have a complex command that I'd like to make a shell/bash script of.  I can write it in terms of $1 easily:  foo $1 args -o $1.ext   I want to be able to pass multiple input names to the script. What's the right way to do it?    And, of course, I want to handle filenames with spaces in them.


Electronic switch with high number of poles

I have two cables each with 10 pins, that connects between two PCBs. I would like to be able to connect and disconnect them from each other. Something like this , however instead of pressing manually I want to automate it.  I have also looked into relay boards but have not found any that have several outputs and it would be too bulky having 20 relays.     To clarify I need to connect/disconnect 20 pins with one signal, it is not necessary to be able to control them individually. The pins are used for SPI communication, however I was hoping to find something like  but with 10 poles instead. We use this for testing purposes and not in the final design, as of now we manually disconnect the cable during each test. So I am looking for some already created device that can act as the "dis-connector".


This might be a silly question, but I can't seem to be able to find the answer anywhere: suppose I have this simple plain TeX code:  \newskip\myskip \myskip = 10pt plus 4pt minus 2pt   Now, how can I access (read) those stretch and shrink parts, those 4pt and 2pt values?  After David's answer: this is what I wanted:  %%%! tex \newskip\spaceskipFixed  % nonsensical values just for testing \spaceskipFixed = 10pt plus 4pt minus 2pt \spaceskip = \spaceskipFixed  % wrong, glue becomes dimen, stretchability and shrinkability gone \def\modifyspaces #1 {%     \spaceskip = #1\spaceskipFixed }  \def\text{Aha oho haha hoho!} \newbox\gauge \setbox\gauge = \hbox{\modifyspaces .5 \text} \def\showline #1#2{     \line{\hbox to\wd\gauge{#1\hfill}\hskip 2em {\spaceskip = 0pt\tt\% #2}\hfill} }  \line{\text\hskip 2em{\spaceskip = 0pt\tt \% unmodified, wild spaces}\hfill} \vbox to 0pt{\noindent\kern \wd\gauge\hbox{\vrule width .1pt height 0pt depth 15mm}\par\vskip -15mm} \showline{\modifyspaces .5 \text}{simple text with modified spaces, width \the\wd\gauge} \showline{\hbox to 92pt {\modifyspaces .5 \text}}{hbox to 92pt, no shrinkability => overfull}  % fixed \def\modifyspaces #1 {%     \spaceskip = #1\spaceskipFixed plus #1\gluestretch\spaceskipFixed minus #1\glueshrink\spaceskipFixed } \showline{\hbox to 92pt {\modifyspaces .5 \text}}{hbox to 92pt, shrinkability preserved, all shiny} \bye


The problem:      A jet flew from Tokyo to Bangkok, a distance of 4800km. On the return   trip, the speed was decreased by 200 km/h. If the difference in the   times of the flights was 2 hours, what was the jet's speed from   Bangkok to Tokyo?   From the problem, we can see that the variables are:  Distance:   T to B = 4800km  B to T = 4800km  Speed:  T to B = $x$km/h  B to T = $x-200$km/h  Time:  T to B = $x$h  B to T = $x-2$h  The problem definitely needs to be solved using the distance formula, $d=s*t$. Rearranging it for time, we get $t=d/s$  What do I do from here? I know from solving similar previous problems that I have to factor it and get the x-intercepts (one of them will be the jet's speed) but how to I solve up to that point when there are two unknowns?  Thank you!


Why did Gates McFadden leave after season 1 of TNG?

In Season 2 of TNG, Dr Crusher (played by McFadden) leaves, I understand, to take a position at Starfleet Medical.  I'm interested, however, in the out of universe reason as to why did McFadden leave for season 2, then return for season 3?


What are the guidelines for sharing blog posts and when it becomes self promotion?

I'm thinking about posting some pieces of code and small tutos on a blog. I'm currently writing these for myself and thought it could be nice to share it with the community.  Then it got me thinking: would it be appreciated if I would ask a question on stackoverflow, and immediately answer it with a link to my brand new fancy blog post ?  I feel like either :    It's basically self promoting a personal blog, which is not the point here   or   It's nice to share some knowledge with the community so why not ?   What do you think ?  edit I wasn't necessarily speaking about answering with just a link. Could be some succint guidelines, and some link to a more elaborate answer, or whatever form it could take to make it interesting enough so it's worth doing it :)


I need help please about being accused on cheating

My prof is accusing me of chatting on an Online exam. I did not cheat. The exam was 30 multiple-choice and 3 short answers. I got all MCQ right, except I made some mistakes in the short answer. In the exam, His concern only on the last 3 short answer questions.  he claimed that he cheats from the test bank ( Answer key of the test book). Also, he claimed that I answered one question similar to the textbook; however, this question's answer included only simple mathematical addition of some numbers. This does not show any valid reasons for his accusation. Moreover, during the meeting, he blamed me for choosing the wrong answer for a question. Thus, I am being blamed for answering questions, whether they are right or wrong. and another question was because I answered similar to the test bank  as he was like," this part of the question was not in the test bank) Secondly, he accused me of violating academic Integrity in my online quizzes, and his concern was, "My other concern is that you spent on average 18 minutes on all online quizzes following the first quiz that included short answers, whereas the class spent anywhere between 40 minutes to 2 hours. The majority of students use a second attempt to improve their score on the first attempt." Note: all the quizzes are theory 30 MCQ, except the first quiz was 25 MCQ and 1 short-answer. He sent me an email to discuss, and then during the online meeting, he asks me to do an oral exam." he was like, so I can prove some evidence,"  and I refused to make the oral exam as it's unfair to be exam orally for something I don't do it. He gave me zero on the midterm and put me under academic integrity. Please advise me what I should do? I have my review of the hearing next week.


Show that for any positive integer n, the kth root of n is either an integer or irrational

I have proved this for the square root of n, but not for any root of n. To prove this where k=2, I showed that: If n is a perfect square then $\sqrt n$ is an integer and not irrational. If $n$ is not a perfect square, assume to the contrary that $\sqrt n$ is rational and can be written as $\frac{a}{b}$. $\sqrt n$ = $\frac{a}{b}$ where $a,b$ are integers with $GCD(a,b) = 1$ then $ n = \frac{a^2}{b^2}$ where $b \neq 1$ But $\frac{a^2}{b^2}$ is not an integer so there is a contradiction. So $ \sqrt n \neq\frac{a}{b}$ and $\sqrt n$ must be irrational. How would I expand this to show that it works for any value of $k$ where $k$ is the $kth$ root of $n$?


Anime with a boy hiring a creature from a stone, meets a man named Dante and starts a journey to collect crystals

I am from India, this anime or animated series (I can't remember this was made by the Japan or other countries) was aired between 2009 and 2012 probably in Jetix/Disney XD (but I'm not sure).   This anime starts with a boy (the main character, I forgot his name) who find a stone (or crystal like thing) in his dad's property, his dad was missing that time. Some day he accidentally hire a creature/monster from that stone. Other day some creature attack him and he was saved by his creature and the story begins.   In his journey to solve the mystery he meets a middle aged man 'Dante' (probably that was the name; this is the only character name I can remember). He had also some stone. After that they meet with one girl and a women (one of the girls is same age with the main boy character and probably will become his partner as the story goes on). Another women probably Dante's partner.  Four of them started their journey to collect all the stone/crystal. They are collecting twelve legendary creatures to defend against their enemy. I watched till they collect 4 legendary creatures' stones. This anime is kind of touch with archeological things.  This story kind of matches with 'Kiba' anime series. This animation series name probably between 5 to 6 letters. That  galactic football was also hiring besides this anime series.


How can i see my iPad screen on a web browser

I'm looking for an application that enables me to preview my iPad screen, on a PC or Mac Desktop. Since I have a presenter on stage that will have an iPad in his hands, and I want to preview his screen on a giant screen behind him.  I was reading some of your answers, but the air play can't find it on either iPad store or Mac store! I'm willing to jailbreak the device if needed.


How to configure Ubuntu Unity to have fixed workspace for external monitor

I am using Unity (ubuntu 13.04). Is there any way to make one of the workspace stay fixed for external monitor.  For example, I am in the middle of the presentation and I just want to quickly switch to another workspace,do somethings and come back to this workspace. This way, my audience, will not notice any interruptions (this is when they are taking notes, and I want to browse my emails).  I have seen my professor doing this on his Mac but I do not know how to do that on Ubuntu.


I remember reading one of my father's books when I was younger.  It was about a guy who ended up getting in trouble with the law and was required to wear a ring that could not be removed and would shock the wearer any time they committed a crime (No matter how minor.)    The book was probably published in the early to mid 80s.  I thought the name of the book was 'The Ring', but I am unable to locate anything.  The cover had a car with a single wheel driving on a metal I-beam.


How to customize default sizes new created objects

I work with metric system and units in millimeters. But all new geometry from Shift+A is 200mm. How can I change it?


Morphism between quotient polynomial rings

Le $\Bbb{K}$ be a field. I want to show wether $\frac{\Bbb{K}[X]}{\langle X^2 \rangle}$ and $\frac{\Bbb{K}[X]}{\langle X^2  + 1\rangle}$ are isomorphic. First thing to note is that there is an nilpotent element $[X]$ in the first quotient. But in the second one I think it will depend on the roots of $X^2+1$ because for example in $\Bbb{F}_2$, $x^2+1=(X-1)^2$ so $[X-1]$ is nilpotent. So in the case where it can't be factorized there is no nilpotent element (how to prove that ?). Otherwise I don't see any morphism we can exhibit. Any hint ?


My 4TB Seagate Backup plus works externally, not internally

I just recently purchased a a 4TB Backup Plus and installed about 1.5GB worth of data. I connected it using the USB 3.0 input on my motherboard. Works fine.  I then decided to use the bare drive itself, internally. So I took apart the external and opened it up. I removed the HDD and installed it in my tower. When I powered on the PC (Windows 8.1 Pro), and tried to open the drive, it gave me the:     This drive must be formatted, blah, blah, blah…   Then:     …the volume does not contain a recognized file system, blah, blah…   I’ve unplugged it from the tower (Desktop) and used the bottom adapter which housed the external drive and connected it using the USB 3.0 again and it works fine. It just won’t work internally using the SATA III ports.  The drive model is  and my file system is NTFS. When I first plugged it in using the USB 3.0, I did a full format.


Preparing an old Windows XP computer for Xubuntu and installing it

I have done research, and am looking to eliminate Win XP from an old computer, and want to run XFCE with libreoffice.   Main question: Do I download and create .exe file on media of XFCE or Xubuntu? Is XFCE something you install AFTER Xubuntu, or does it include Xubuntu? Should I leave WinXP on computer, then install OS which will let me wipe drive before installing new OS? If there is a great installer guide that answers these questions, point me that way!  If not, details appreciated.


NullPointerException when using Scanner.nextInt()

I am creating a program that calculates how many numbers between A and B are divisible by K. This program should allow the user to input first the number of test cases then get the corresponding A, B, and K values depending on the number of test cases. Sample Input:      2     1     10     3     8     20     4   Output would be:      Case 1: 3     Case 2: 4   However, I  keep getting a NullPointerException right after hitting enter after the second line. In this case, I only get to enter:       2      1   Here is the code:      import java.util.Scanner;  public class ABK {  public static void cases(int no, int[] first, int[] second, int[] div){     int[] outputs = null;     for(int i = 0; i < no; i++){         for(int x = first[i]; x <= second[i]; x++){             if(x%(div[i]) == 0)                 outputs[i]++;             else continue;         }     }      for(int i = 0; i < no; i++){         System.out.println("Case " + (i+1) + ": " + outputs[i]);     } } public static void main(String[] args){     int noOfCases = 0;     int[] a = null, b = null, k = null;     Scanner scanner = new Scanner(System.in);     noOfCases = scanner.nextInt();     if(noOfCases < 0 || noOfCases > 1000){         System.out.println("Invalid number of cases. Only numbers from 1 to 100 are allowed.");         System.exit(0);     }     for(int i = 0; i < noOfCases; i++){         a[i] = scanner.nextInt(); //THIS IS WHERE THE NULLPOINTEREXCEPTION APPEARS         b[i] = scanner.nextInt();         k[i] = scanner.nextInt();     }     for(int i = 0; i < noOfCases; i++){         if(a[i] < 1 || a[i] > 1000){             System.out.println("Invalid value of a. Only numbers from 1 to 1000 are allowed.");             System.exit(0);         }         if(b[i] < 1 || b[i] > 1000){             System.out.println("Invalid value of b. Only numbers from 1 to 1000 are allowed.");             System.exit(0);         }         else if(a[i] > b[i]){             System.out.println("Invalid value of b. It must be larger than a.");             System.exit(0);         }         if(k[i] < 1 || k[i] > 1000){             System.out.println("Invalid value of k. Only numbers from 1 to 9999 are allowed.");             System.exit(0);         }     }     cases(noOfCases, a, b, k); }   }  I've tried other "fixes" such as initializing the Scanner variable or using a new class that implements scanner.nextInt() but none worked for me. Thank you in advance for your help.


"Unable to generate the derived image located at public://styles/uc_category/public/tg.jpg"

(Drupal 7 under Linux)  This is clearly a Drupal permissions problem, but I'm baffled. If I   rm -rf styles   and refresh the page causing the error, styles and it's sub-dirs are re-created thus:  drwxr-xr-x 3 www-data www-data 4096 Jan 25 16:07 styles  drwxr-xr-x 3 www-data www-data 4096 Jan 25 16:07 uc_category  drwxrwxr-x 2 www-data www-data 4096 Jan 25 16:07 public   But I still get the error. And I still get it if I  chmod -R 777 styles   Any suggestions?


No upgrade available for 19.04 from 18.10

I'm pretty new to running linux, but I know that 19.04 was released today and I wanted to upgrade from my current 18.10. However, when I follow the release notes here:  I get the message "The software on this computer is up to date". I made sure that my update settings are set to "any new version" and "normal" in the /etc/update-manager/release-upgrades file.   What am I doing wrong?  Thanks for the help!  Side note: I had to disable this PPA:  because it would cause errors in apt updating. Do I need to re-add it? If so how do I do so without it giving me an error?  Edit: I have followed the procedure recommended in the documentation which is identical to the suggested duplicate, but I am not given the option to upgrade. I have not yet tried the   do-release-upgrade -d    option as I don't want to upgrade to the developer version.


I'm currently learning Java, I'm just curious about the code that I wrote a minute ago, it works, but I want to know if there is a better alternative (that isn't "use the clear method").      public static void main(String[] args) {      ArrayList al = new ArrayList();      al.add("A");     al.add("B");     al.add(5);      System.out.println(al.size());      Iterator i = al.iterator();      while (i.hasNext()) {         Object next = i.next();         System.out.println("Removing " + next.toString() + "...");         al.remove(next);         i = al.iterator();     }      System.out.println(al.size()); }   Especially, because I don't really know what can be in a specific position in an ArrayList (they contains objects of every kind), I used a generic "Object next" variable. I don't know if it is acceptable.  I know that there are methods to clear an ArrayList, I just wanted to try to understand how ArrayLists works, thank you.


Today I started to create a set of generic answers for most common SO questions.  The main reason I want this to be done (by my hands or not) is that it would make closing such questions very quick and simple.  When you see a question asked on SO for the third time in an hour and you have some spare time, please create a generic question and answer so that, in the future, such questions could be easily marked as duplicates.  Here's my first post of this sort:    I know that many questions have such generic answers. But some don't, and I'd love to see the gaps filled.  So, once again, whenever you find a question which is trivial and can't find a valid duplicate to close it, please spend some time and create such question and answer.


ORA-00937: - "not a single-group group function"

I have  a select  select distinct     min(trunc(ALL_SUBS_DAY.CHARGE_AMT * SUP.SHARE_USAGE, 4)) + (ALL_SUBS_DAY.CHARGE_AMT - sum(trunc(ALL_SUBS_DAY.CHARGE_AMT * SUP.SHARE_USAGE, 4))) as CHARGE_AMT from table names;   when I try to run it I get not a single-group group function. If I do it like this  select      min(trunc(ALL_SUBS_DAY.CHARGE_AMT * SUP.SHARE_USAGE, 4)) + (ALL_SUBS_DAY.CHARGE_AMT - sum(trunc(ALL_SUBS_DAY.CHARGE_AMT * SUP.SHARE_USAGE, 4))) as CHARGE_AMT from table names group by SUBS_DAY.CHARGE_AMT, SUP.SHARE_USAGE;   it works. Wasn't distinct supposed to work like group by? Do I really need to list every single column or is there a way not to do it?


Is it a good idea to make most actions in a game driven by simple tiny threads (in Java)?

I'm thinking of for example making the jump action of a character, that takes ~1s, a distinct runnable, so then other threads can read its state, with additional control over the action itself by the "action thread". Are people doing this? What is there to consider when thinking about creating and destroying hundreds (or thousends) of threads a second in a bigger game or other application?


At least how many numbers are needed to be taken to be sure that there are at least 11 numbers among these numbers where the difference between any two is divisible by 7?


How to convert a single char into an int

I have a string of digits, e.g. "123456789", and I need to extract each one of them to use them in a calculation. I can of course access each char by index, but how do I convert it into an int?  I've looked into atoi(), but it takes a string as argument. Hence I must convert each char into a string and then call atoi on it. Is there a better way?


Question building in English vs. in French

Question about language grammar etymology. In French the question «Do you love?» can be written as «Aimez-vous?» in German — «Mögen Sie?», but in English — «Do you love?». Why should we use the verb «to do» in order to form the question? Why, according to the English grammar, it is not possible to build the question only with words inversion, e.g. «Love you?» like in French or German?  In other words, why English which has quite a common Latin/Roman base with French and German has such different question building form.  Thanks.


Is there a term for creating a new meaning for an existing word?

I'm looking for a technical term for using a noun as its own verb form where such usage is not extant. For example, using intellect as a verb (to intellect). Is there such a term? It doesn't seem to be a neologism or an example of metonymy.


Artificial Neural Network for time series analysis - $R^2$ scores

I've looked at an introduction to simple ANNs for time series analysis . In the tutorial, the train dataset r2 score is 0.897 and the test dataset r2 score is 0.789. They end up with some pretty neat predictions (see graph below, also from the same tutorial). Now my question is, for real world time series data, is there a consensus on what r2 scores make for an acceptable model?


Is there any child safety software for Ubuntu?

I have a son, 13 years old, who needs his laptop for school for better writing, etc. But naturally he wants to play with it after working.  Are there any programs or packages for safety on the internet? A program limiting the time on the web and filtering the webpages would be great.


Difference between Cohen's d and Hedges' g for effect size metrics

For an effect size analysis, I am noticing that there are differences between Cohen's d, Hedges's g and Hedges' g*.    Are these three metrics normally very similar?   What would be a case where they would produce different results?  Also is it a matter of preference which I use or report with?


Globally associate file type with certain application

I don't need "Ubuntu-tweak" and i know about GUI method of associating certain files with certain applications using right click and "Open with". I am having problem setting filetype association globally in a file:  /usr/share/gnome/applications/defaults.list   E.g.:  image/x-psd=gimp.desktop   If i want to open all PSD's in a photoshop, i have created photoshop.desktop file and placed it under /usr/share/applications. Now when i press Super (windows) key and type Photoshop i see that icon, but i can't:   drag'n'drop that on my desktop. How can i do that? if i change image/x-psd=gimp.desktop to image/x-psd=photoshop.desktop it still opens in a gimp. Why?   Thanks in advance.


Word for phrases that are examples of what they describe

Is there a word (or phrase) for phrases that are examples of what they describe? For example, "You the verb" to tell someone they forgot a verb in an online posting, or "spacesmakethingseasiertoread".


Nullpointer Exception - Concurrent Hashmap

I want to increase a counter for a ConcurrentHashmap, but the key can be deleted at any time by another thread. So I check if the key still exists before increasing the counter.  I have the following code:  if(this.myMap.containsKey(key)) {     this.myMap.put(key, this.myMap.get(key) + 1); }   myMap is created like this:  private Map<String, Integer> myMap = new ConcurrentHashMap<String, Integer>();   But from time to time I get a NullPointer Exception in the line where I increase the integer. This doesn't happen often (maybe 1 out of 10 Million runs).  Is there another way to increase the counter? Or Do I even need a HashMap?


Multiplying Taylor series and composition

I have two questions:  A. I know the taylor series for $\arctan(x)$ and for $e^x$. How do I find the series for $\arctan(x)\cdot e^x$ ?  B. Say I want to find the series for $\arctan(g(x))$, do I just subtitue $x$ with $g(x)$, Or do I have to start the process of finding the series from the beginning?  Thanks!


The new notification system didn't notify me of my Investor badge :(

Today I got awarded an Investor badge:    ... but the new notification system didn't show me no shiny grey (1) (or show me it at all...):    (it's not any further down, I promise)  Needless to say, I'm very angry:


Shortcut for quick directory navigation in the bash shell

I'm looking for shortcuts that would help me to navigate directories quickly and efficiently.


The past couple of days I've been periodically getting this pop up through my antivirus. I'm not familiar with what to do with malware but I have made sure there are no recently installed apps- I have uninstalled and reinstalled my Chrome- 'reset' and 'repaired' the automatic windows edge and yet it still pops up.  I don't know what to do from here and I'm really hoping someone can help me.


How to Integrate this function $\int(1-x^2)^ndx$

The actual question was to find the area bounded by the curve $y=\int_{-1}^{1}(1-x^2)^ndx$ and coordinate axes. But I haven't came across these type of problems with power $n$.


Determine if a triangle is right angled with only coordinates

What is the easiest way to determine that, given 3 coords, they DON'T form a right angled triangle?  EG, (0, 0, 0), (0, 1, 0), (1, 0, 0) - forms a right angled triangle  (0, 0, 0), (0, 1, 0), (1, 0.5, 0) - does not form a right angled triangle


Upgraded from 16.04 to 17.04, cannot connect to libraries

I was upgrading my system (on laptop) from 16.04 to 17.04. To do so I upgraded from 16.04 to 16.10 to 17.04 using sudo do-release-upgrade -d. It all went fine, until I tried opening my browsers (firefox and chrome). Then I performed a sudo apt-get update and got the following. How do I fix this?  Err:1 http://dl.google.com/linux/chrome/deb stable InRelease   Could not resolve 'dl.google.com' 0% [Working]  Err:2 http://ca.archive.ubuntu.com/ubuntu zesty InRelease   Could not resolve 'ca.archive.ubuntu.com' 0% [Working] Err:3 http://security.ubuntu.com/ubuntu zesty-security InRelease   Could not resolve 'security.ubuntu.com' 0% [Working] Err:4 http://ca.archive.ubuntu.com/ubuntu zesty-updates InRelease   Could not resolve 'ca.archive.ubuntu.com' 0% [Working] Err:5 http://ca.archive.ubuntu.com/ubuntu zesty-backports InRelease   Could not resolve 'ca.archive.ubuntu.com' Reading package lists... 0% Reading package lists... Done W: Failed to fetch http://ca.archive.ubuntu.com/ubuntu/dists/zesty/InRelease  Could not resolve 'ca.archive.ubuntu.com' W: Failed to fetch http://ca.archive.ubuntu.com/ubuntu/dists/zesty-updates/InRelease  Could not resolve 'ca.archive.ubuntu.com' W: Failed to fetch http://ca.archive.ubuntu.com/ubuntu/dists/zesty-backports/InRelease  Could not resolve 'ca.archive.ubuntu.com' W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/zesty-security/InRelease  Could not resolve 'security.ubuntu.com' W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/InRelease  Could not resolve 'dl.google.com' W: Some index files failed to download. They have been ignored, or old ones used instead. $ exit exit  Script done on Sat 15 Apr 2017 03:24:29 PM ADT   edit: This question has not been answered, and none of the other answered questions have solved this.  (edit: honestly, I have given up and downgraded back to 16.04)


Number of helpful flags appearing different

The User Profile Page shows how much helpful flags a user has raised. Clicking on that number redirects to another page that shows the complete details of the flags, their number, helpful, declined, etc. The number of helpful flags shown there is not equal to the number I view on the Profile Page.  It's not the first time but I've noticed it many times before as well.   Is this happening only with me or anybody else has experienced it?


Understanding differences between S&P500 index-tracking ETFs

I'm trying to understand the difference between S&P 500 trackers. Example:     SPY   IVV   VOO     They all have different prices (IVV being $1 more, on average than SPY, and VOO being about 50% of the others). Additionally in short observation today, IVV seems to be tracking more closely to the S&P 500.  Am I miss understanding the purpose of trackers -- surely they should all be pretty much tracking the S&P500?  Is there a good explanation of this somewhere?


Finite Dimensional $k$-Algebra has finitely many Maximal Ideals

I have a question about an argument used in Tamas Szamuely's "Galois Groups and Fundamental Groups" in following excerpt (see page 102):  We start with affine variety $X$ of dimension $n$. According Noether Normalization Lemma there exist an injection $\mathcal{O}(\mathbb{A}^n_k) = k[x_1,...,x_n] \to  \mathcal{O}(X)$.  The contravariant category equivalence between affine varieties over $k$ and that of finitely generated reduced $k$-algebras induce a surjection $\phi: X \to \mathbb{A}^n_k$.  Let $M_p=(x_1-a_1,..., x_n -a_n)$ an maximal ideal of $\mathbb{A}^n_k$.  I have following two questions:   Why is the fiber $\mathcal{O}(X)/M_P \mathcal{O}(X)$ a finite dimensional $k$-algebra? If 1. holds: Why does it imply that a finite dimensional $k$-algebra has finitely many maximal ideals?


Separate /home partition on arch-based distros take more space than used

/dev/dm-1 861G 325M 817G 1% /home   I have a separate luks encrypted /home partition with 861G allocated out of a 931G HDD.   The usage is around 1%, but the availabe space is only 817G.   I am having this problem with multiple Arch-based distros like Manjaro, Antergos. I reported this on their forums, but couldn't find a solution yet. They concluded this might be a problem with inode configuration. So I think this must be a problem irrespective of distros.   Is it possible to configure a separate /home partition on a 1TB HDD?  Why is the reported available space only 817G out of allocated 861G?


I would like to have a left brace around equations in the align environment.  How can I do this?  (I would like to use this environment because I would like to number each individual equation to be able to refer to it.)    So my code looks like this, and I want to have a curly brace on the left around the the 3 equations.  How can I do this?  \begin{align} & F= ma \\ & v= at \\ & W= F s \end{align}   EDIT: I didn't want to use the empheq package, because I get the error ''empheq.sty'' not found.


Show error messages and information that a program was killed on another terminal

If I open a program, say evince, from the GNOME GUI, it is not attached to a terminal. If I send it a signal, it acts accordingly but nothing shows up in my terminal.  If I were to open it in a terminal to start with and allow it to run in the foreground, it would show what signals it had received.  Say I run evince as just evince from the terminal. And then in another, I run ps -e, find its PID, and then do kill -11 [PID]. It will print out "Segmentation fault (Core dumped)". For other signals, it may print "Received signal..." How can I start a terminal and have it shows signals that are sent to a program that was not started within a terminal but rather a GUI?  Is it possible to open a program in the GUI, and then attach a terminal to it so I can see the same behavior as if I had opened it from within the terminal?


Adding new menu item to QGIS Desktop app?

I need to add new menu item to the top level menu of QGIS Desktop (2.7.0); I.e. it shall be on same level as "Project", "Edit", "View", "Layer" etc.  As far as I know there is pretty nice way how hide menu items (Settings->Customization) Plus using QgisInterface () I can add new items to Menus already defined in QGIS (addLayerMenu, addPluginToDatabaseMenu etc) from my plugin code.  But I need new Menu item on top layer (this is req from customer).


$$\lim_{n \rightarrow \infty} \sum_{k=1}^n \sqrt{n^4+k} \  sin\frac{2k\pi}{n}$$ I have found this Riemann Sum look-alike, but I have no idea how to approach it. Can you perhaps help me solve this?  The answer should be $-\frac{1}{4\pi} $.


When will "Present Perfect vs. Past Tense" cases be affected by culture?

Regarding actions taken in the past, besides the differences those two tenses have semantically, my teacher shared that it could be a British vs American English case.   When talking about past action, British prefers present perfect because they take into account that the effect from their past action still happens until now. As for American, they prefer to state the action only. It happened in the past, so past tense it is.     I have had dinner. [British]   vs.      I had dinner. [American]   I hope to hear it from the native speakers, both British and American. What do you think about this? Is it true?  If it is, I don't think it can apply to all cases of past actions. There have to be cases when both style agree to use the same tenses. Could you please help me define the situation when this kind of difference applies and when doesn't?


Remove HTML Tags from an NSString on the iPhone

There are a couple of different ways to remove HTML tags from an NSString in Cocoa.   is to render the string into an NSAttributedString and then grab the rendered text.   is to use NSXMLDocument's -objectByApplyingXSLTString method to apply an XSLT transform that does it.  Unfortunately, the iPhone doesn't support NSAttributedString or NSXMLDocument. There are too many edge cases and malformed HTML documents for me to feel comfortable using regex or NSScanner. Does anyone have a solution to this?  One suggestion has been to simply look for opening and closing tag characters, this method won't work except for very trivial cases.   For example these cases (from the Perl Cookbook chapter on the same subject) would break this method:  <IMG SRC = "foo.gif" ALT = "A > B">  <!-- <A comment> -->  <script>if (a<b && a>c)</script>  <![INCLUDE CDATA [ >>>>>>>>>>>> ]]>


How do I transfer the solaris syslogs to another windows server. Please share the source and destination configuration steps in detail.


What is the inverse of   $$f(x)=\sin(x)+x.$$  I thought about it for a while but I couldn't figure it out and I couldn't find the answer on the internet.  What about  $$f(x)=\sin(a \cdot x)+x$$  where $a$ is a known real constant.  Thank you for taking the time to read this question! Sorry if this has been asked before...


What introductory courses on statistics are available online?

I'm looking for a full online course on college-introductory level statistics (and beyond). I've seen a few options on statistics.com ($600usd online courses ouch), and coursera (starts over a month from now).   I wonder if there are other good resources that could constitute a course on statistics (books seem to supplement courses well, but not replace them quite perfectly). Academic credit & certification options are a plus, but not necessary.  Thoughts?


"unresolved external symbol" error when trying to compile C++ project

I am trying to implement a few classes but i got the following error when compiling the codes. I have tried to removed all the redundant codes but none of them helps. I have no idea what went wrong.  Here is the error i get when compile the code:  Severity    Code    Description Project File    Line Error   LNK2019 unresolved external symbol "public: __thiscall FullArray<int>::FullArray<int>(unsigned int)" (??0?$FullArray@H@@QAE@I@Z) referenced in function _wmain  FinancialDerivatives    C:\Users\Jeremy Nguyen\Documents\Visual Studio 2015\Projects\FinancialDerivatives\FinancialDerivatives\FinancialDerivatives.obj 1 Error   LNK1120 2 unresolved externals  FinancialDerivatives    C:\Users\Jeremy Nguyen\Documents\Visual Studio 2015\Projects\FinancialDerivatives\Debug\FinancialDerivatives.exe    1 Error   LNK2019 unresolved external symbol "public: virtual __thiscall FullArray<int>::~FullArray<int>(void)" (??1?$FullArray@H@@UAE@XZ) referenced in function _wmain  FinancialDerivatives    C:\Users\Jeremy Nguyen\Documents\Visual Studio 2015\Projects\FinancialDerivatives\FinancialDerivatives\FinancialDerivatives.obj 1   FullArray.h file:  #pragma once #include <vector>  template <class V> class FullArray { private:     std::vector<V> m_vector;        // Use STL vector class for storage  public:     // Constructors & destructor     FullArray();     FullArray(size_t size);     FullArray(const FullArray<V>& source);     FullArray<V>& operator = (const FullArray<V>& source);     virtual ~FullArray(); };   FullArray.cpp file:  #include "stdafx.h" #include "FullArray.h"   template<class V> FullArray<V>::FullArray() {     m_vector = std::vector<V>(1);   // vector object with 1 element }  template<class V> FullArray<V>::FullArray(size_t size) {     m_vector = std::vector<V>(size); }  template<class V> FullArray<V>::FullArray(const FullArray<V>& source) {     m_vector = source.m_vector; }  template<class V> FullArray<V>& FullArray<V>::operator=(const FullArray<V>& source) {     // Exit if same object     if (this == &source) return *this;      // Call base class constructor     //ArrayStructure<V>::operator = (source);      // Copy the embedded vector     m_vector = source.m_vector;      return *this; }  template<class V> FullArray<V>::~FullArray() { }   main file:  #include "stdafx.h" #include "FullArray.h"  int _tmain(int argc, _TCHAR* argv[]) {     FullArray<int> tmp(5);     return 0; }


babel package and lstlisting caption incompatibility

I am using babel package for Turkish language and I also use listings package. A code sample for one of my listings is as follows:  \begin{lstlisting}[label=some-code,caption=Poo Class] public class Person {      public int ID { get; set; }     public string Name { get; set; }     public string Surname { get; set; }  } \end{lstlisting}   As header, what I am getting is this:     Listing 7.1: Poo Class   I would like it to be like this:     Kod Örneği 7.1: Poo Class   Am I asking too much?


Which partition should I install the bootloader on?

I am about to install Ubuntu 10.10 on my Windows 7 system  I will be dual booting with Windows 7 and want to use Windows 7 as my default OS for now. Where should I put the bootloader/GRUB; on the Windows partition or the root partition of Ubuntu? I have read elsewhere that Windows 7 tends to corrupt grub2.  Also, is there a way to use Windows 7's bootloader instead of selecting the OS from grub? I don't know much about bootloaders.


How to edit /etc/fstab if it in ro mode?

Me set "data=journal" in etc/fstab file, after that i reboot, but system doesn't booting. After that me boot from LIVE-CD and tried to delete "data=journal" from /etc/fstab, but file works in ro mode.  blkid & /dev/disk/*:  ubuntu@ubuntu:~$ sudo blkid /dev/sda1: UUID="5aab4fef-bdbd-4f6f-bf59-7c164354a8fa" TYPE="ext4" PARTUUID="93d3e9f3-01" /dev/sr0: UUID="2018-10-17-22-44-30-00" LABEL="Ubuntu 18.10 amd64" TYPE="iso9660" PTUUID="133f436e" PTTYPE="dos" /dev/loop0: TYPE="squashfs" /dev/loop1: TYPE="squashfs" /dev/loop2: TYPE="squashfs" /dev/loop3: TYPE="squashfs" /dev/loop4: TYPE="squashfs" /dev/loop5: TYPE="squashfs" /dev/loop6: TYPE="squashfs" /dev/loop7: TYPE="squashfs" ubuntu@ubuntu:~$ ls -l /dev/disk/by-id total 0 lrwxrwxrwx 1 root root  9 Jan 10 16:17 ata-VBOX_CD-ROM_VB2-01700376 -> ../../sr0 lrwxrwxrwx 1 root root  9 Jan 10 16:17 ata-VBOX_HARDDISK_VB78947f38-edb217dd -> ../../sda lrwxrwxrwx 1 root root 10 Jan 10 16:19 ata-VBOX_HARDDISK_VB78947f38-edb217dd-part1 -> ../../sda1 ubuntu@ubuntu:~$ ls -l /dev/disk/by-uuid total 0 lrwxrwxrwx 1 root root  9 Jan 10 16:17 2018-10-17-22-44-30-00 -> ../../sr0 lrwxrwxrwx 1 root root 10 Jan 10 16:19 5aab4fef-bdbd-4f6f-bf59-7c164354a8fa -> ../../sda1 ubuntu@ubuntu:~$ ls -l /dev/disk/by-label total 0 lrwxrwxrwx 1 root root 9 Jan 10 16:17 'Ubuntu\x2018.10\x20amd64' -> ../../sr0


I tried to install , from snap, but after installation I tried to run it with lsd, and I got the error  cannot open directory'.': Permission denied (os error 13)  Any ideas?  Edit


Yosemite auto creates multiple desktops (spaces) on main monitor

Since upgrading to Yosemite I've been having issue with OS X creating additional desktops on my main monitor for no apparent reason. I usually have 3 different desktops setup on my main monitor and just one on my second monitor. By the end of the day, OS X will usually have created 2-3 extra desktops automatically.  I can't find any setting or shortcut that might be causing this to happen. There also doesn't seem to be any reason for it since it can happen as soon as I boot up my computer.  Is there a way to set a maximum number of desktops so I can prevent this from happening?  Image from related question -


be confused the use between adjective and adverb when it is in front of adjective

How to use adjective and adverb correctly without being confusing. In this case because when I translate this sentence from my mother language to English, it fairly seem to be the same. Please help me. Thanks in advance         Cable cars are environmental friendly.   Cable cars are environmentally friendly.


How to open a web page from my application?

I want to make my WPF application open the default browser and go to a certain web page.  How do I do that?


Is it safe to unplug a UPS during operation?

Interestingly there is no word in the manual and nothing to be found on the internet. But it seems like an obvious question: While a UPS (let’s use APC Smart-UPS 1500RM as an example) drives equipment/server, is it safe to disconnect the mains power cable? Which implications does this action have? I have done this in the past and did not have issues. However, it does not feel right because that would interrupt earth connection as well. How come then, that the manual contains lots of obvious warnings but does not explicitly warn against disconnecting during operation?


Showing an isometric isomorphism between $C([0,1])$ with sup norm to itself

Let $T:C([0,1])\rightarrow C([0,1])$ defined by  $Tf (t) = f(t) + \int_{0}^{t} f(s) ds$,  It is easy to show that $T$ is a linear and continous operator, but I'm stuck about showing injective,surjective or exhibiting its inverse. How can i compute those things?


Prove that for any positive integer $n $: $(2n)!$ is divisible by $({n!}) ^2: $   If you know a solution to the problem, please help..  Sorry, this problem was edited by another user who changed some values. I have now fixed the problem.


I'm not very familliar with jQuery and it's functions.  Does anyone know what these declarations are doing? (Btw. they wrap the entire .js content)   (function ($) { 'use strict' ... })(jQuery);  (function () { 'use strict' ... })();   The second I guess, is a declaration of an anonymus function to not make variables inside accessable from outside.  I know there's a ready function that is called when the DOM was loaded.   $(function () { 'use strict' ... });   Though I can't figure out what the first 2 functions do.


I have this following query and I want to display the results where masini > 2 but when I run the query it says that 'masini' is not an existing column but it's the name of a custom column I defined on the first row. I am new to MySQL.. can anyone point me in the right direction? This is my query:  SELECT pers.serie_buletin AS persoana, COUNT(prop.serie_buletin) AS masini  FROM persoana pers  JOIN proprietate prop ON pers.id_persoana = prop.serie_buletin WHERE masini > 2 GROUP BY persoana ;   I defined the column on this line, in this part "COUNT(prop.serie_buletin) AS masini" but it says "Error Code: 1054. Unknown column 'masini' in 'where clause'". What am I missing?


How to calculate ray polygon intersection?

I'm in a class where we are creating a ray tracer from the ground up in C++. I'm at a point where I can't seem to wrap my head around the math that is required to calculate the point at which a ray intersects a polygon.  We have some direction for how to do this, but all of the class materials as well as my Googling of the subject have not helped.  These are the functions we must complete:  bool polygon::Intersect(const ray &R, intersection &inter) {     // To Do: If you have implemented the "CalculateNormal" method      // below, should already be calculated and placed in the member      // "n".     //     // Now, using n, you need to calculate the intersection of the     // ray with the plane containing the polygon.  Then, once you      // have that point, you need to loop through each edge in the     // polygon and make sure the point is to the left of that edge.     //     // If it is to the left of every edge, then fill the structure     // inter with all of the data for the intersection and return      // true, if not, return 0.      //      // Don't forget to check to see if the t you calculate for the     // ray is > 0.      return false; }  void polygon::CalculateNormal(void) {     // To Do: Use the edges of the polygon to calculate the normal     // of the polygon. You should be careful to take care of the      // case where two edges give you a zero normal.  Place the      // normal into the member "n" so that the intersection method     // can use it when called.     //  }   Could someone please explain this in a bit further detail?  Note: I am not asking for anyone to write the code or do my homework for me, but instead help me understand what exactly is going on here.  Thank you.


When using (s), should "is" or "are" be used?  Regardless of what option(s) is decided.  or Regardless of what option(s) are decided.


What provokes an opportunity attack?  In 3.X moving out of a threatened square, standing up from prone, casting a spell (unless cast defensively), or making a ranged attack provoked, while in 4e moving out of a threatened square or making a ranged/area attack provoked.


How can I remotely trigger a video capture with adb?

Currently, I'm using DroidCam to expose my cell phone as a webcam to Linux, and recording a stream with VLC. This works, but when mastering a video (and not streaming live), I don't need a webcam. I just need a raw video file. Is there anyway with ADB to trigger recording a live stream and just saving it under /data?


I wonder why the degree of the zero polynomial is $-\infty$ ?  I heard that, it is $-\infty$ to make the formula $\deg(fg)=\deg(f)+\deg(g)$ hold when one of these polynomials is zero. However, if that was the only reason we could have said that it is $\infty$ instead.


Bending of light Ray in radially varying refractive index

If light passes near a massive object, the gravitational interaction causes a bending of the ray. This can be thought of as happening due to a change in the effective refrative index of the medium given by $$n(r) = 1 + 2 \frac{GM}{rc^2}$$ where $r$ is the distance of the point of consideration from the centre of the mass of the massive body, G is the universal gravitational constant, M the mass of the body and c the speed of light in vacuum. Considering a spherical object find the deviation of the ray from the original path as it grazes the object.


Why would a student go to a lecture at all if everything was in the   book already? The lectures make sense if and only if the lecturer   tells more than in the book(s) and in more detail (or at least, in a   better/more clear way). [not my comment]   Especially in light of the Internet in general, what is the added value of a lecture over a (hypertext)book?  Reasons I can think of:   spoken word might stick better, because our language is not primarily based on text, the possibility to ask for clarification, some material might not translate well to media   I dislike those arguments, because a huge class can neither run at a comfortable speed for all at once nor answer everyone's questions. The expectation seems to be that the students should be homogeneous and everyone nonconforming should be filtered out.   personal contact affects us on a deeper level, role models are important   Depending on the class size, even that is doubtful.   to form communities,   which would substitute or supplement the professors, but obviously at a different rate.  This is a trick question, because it depends on the style of the lecture.  In my experience the lecturer is acting as a medium and I'm watching them half the time writing on the board, or someone is asking obvious or distracting questions.


Here is the situation.  I have hexagonal board,and a unit on it,with speed or move value 4.Diffrent terrain has a diffrent cost.When i click on the unit,game should show me a move range.  My solution was to check each  hex in range of 4,with A* pathfinding,and if path cost was less than 4 then this hex was in range.Finally game nicely show me range of that unit.  My question is:   Is there other solution to search for range on hex grids or square grid,because even if i am really proud of what i did in my solution,i think,it is a little to exaggerated?:))  What make me ask this question?I noticed that when unit speed is 4 or 6 or even 8,time to computing range for my computer was really good,but when speed was 10 and more i noticed that i needed to wait few second to compute.Well in real games i rather dont see something like this and my A* pathfinding is rather well optimized,so im thinking that my solution is wrong.  Thanks for any replies.


How to join these two tables without Foreign Key?

I want to generate monthly report and the total in a year based on position(jawatan) that has been applied. Table 1 : tpermohonan (mohon_id pemohon_id mohon_tarikh mohon_online)     mohon_id pemohon_id mohon_tarikh mohon_tkhluput     1 2 2018-12-23 2019-12-23     Table 2 : kod_jawatan (jawatan_id jawatan_kod jawatan_nama)     jawatan_id jawatan_kod jawatan_nama     1 A0001 accountant     My desired output is :     Bil Jawatan(Position) Jan Feb March Apr May Jun July Aug Sep Oct Nov Dec Total


What would be the least expensive way to boost a DC voltage?   The aim is to convert 1.2 V/1.5 V (from an AA/AAA cell) to 3.3 V to power a small 8-bit microprocessor, like Atmel ATtiny45 or ATtiny2313, and also (if possible) 6 V to power a buzzer.  Also, what would be the maximum current one could draw safely from an alkaline battery, after boosting it to 3.3 V/6 V?  Finally, how I could compute the duration for which the alkaline battery would last, given a certain consumption?


Decomposition of Harmonic function into sum of holomorphic and anti-holomorphic function

How do you prove that a harmonic planar mapping $f(x,y) = u(x,y) + i v(x,y)$ for real $u,v$ can be written as $f(x,y) = \phi(x,y) + \overline{\psi}(x,y)$ where $\phi$ is a holomorphic function, and $\overline{\psi}$ is an anti-holomorphic function (conjugate of a holomorphic function)?


Why does “expecto patronum” work on a boggart-dementor?

In the third book Lupin uses a boggart to practice expecto patronum with Harry. Why does this work? The boggart is simply changing its appearance to look like a dementor it is not actually becoming one?


I have seen horses falling down many times in war movies while running. How do they make horses fall down in war movies? Are they highly trained to know fall down at some place or some barriers are given to them?