I tried compiling a document with an included Hebrew word. I copy and pasted the \usepackage example loading English and French as an example. Since then, my document will not compile no matter what I do. I have completely removed babel from the preamble and it now complains that I am not loading English. I tried using \usepackage[english]{babel}, but then it tells me I'm not loading french. I add french, it complains about my encoding. But I don't have a single french word or accent in my text!   \documentclass{report} \setcounter{tocdepth}{3} \begin{document}   This will not compile, with the following logfile:  This is pdfTeX, Version 3.1415926-2.5-1.40.14 (TeX Live 2013/TeX Live for     SUSE Linux) (format=pdflatex 2013.12.10)  20 MAR 2014 19:43 entering extended mode  \write18 enabled.  file:line:error style messages enabled.  %&-line parsing enabled. **/home/michael/Dropbox/ProjectMalynne/TEX/.Main.tex.swp (/home/michael/Dropbox/ProjectMalynne/TEX/.Main.tex.swp LaTeX2e <2011/06/27> Babel <3.9f> and hyphenation patterns for 78 languages loaded. (/usr/share/texmf/tex/latex/base/book.cls Document Class: book 2007/10/19 v1.4h Standard LaTeX document class (/usr/share/texmf/tex/latex/base/bk10.clo File: bk10.clo 2007/10/19 v1.4h Standard LaTeX file (size option) ) \c@part=\count79 \c@chapter=\count80 \c@section=\count81 \c@subsection=\count82 \c@subsubsection=\count83 \c@paragraph=\count84 \c@subparagraph=\count85 \c@figure=\count86 \c@table=\count87 \abovecaptionskip=\skip41 \belowcaptionskip=\skip42 \bibindent=\dimen102 ) (/usr/share/texmf/tex/latex/cjhebrew/cjhebrew.sty Package: cjhebrew 2004/08/27 v. 0.1a cjhebrew Hebrew Typesetting System ) (/tmp/.Main.tex.aux  /tmp/.Main.tex.aux:6: Package babel Error: You haven't loaded the language     english yet.  See the babel package documentation for explanation. Type  H <return>  for immediate help.  ...                                                l.6 \select@language{english}  Here is how much of TeX's memory you used:  244 strings out of 493315  2957 string characters out of 6145892  52158 words of memory out of 5000000  3777 multiletter control sequences out of 15000+600000  3640 words of font info for 14 fonts, out of 8000000 for 9000  957 hyphenation exceptions out of 8191  23i,0n,17p,200b,49s stack positions out of 5000i,500n,10000p,200000b,80000s  /tmp/.Main.tex.aux:6:  ==> Fatal error occurred, no output PDF file produced!   Again, I'm not loading babel, and I keep getting exceptions. I tried trashing the aux files, but it's no use. Any ideas?

I've been trying to change the language of my LaTeX document by replacing \usepackage[swedish]{babel} with \usepackage[english]{babel} but I only get this message:  ! Package babel Error: You haven't loaded the option swedish yet.   I've read in an other question at this forum that compiling enough would solve the problem, but that doesn't work for me. Does anyone know what I should do?


I have been using an authentication through my Gmail account because  many years ago I thought it was a good method from a security standpoint, (even if the fact to use an E-mail as an account is a huge source of problems in the security field: the 2 of them don't belong to the same class of privacy level, one is public when the other is private).  Since recent events I am now convinced of the contrary: Google doesn't take care enough of security and privacy and at the same time is becoming too large a data keeper. It will become too large a target and probability to fail is increasing with the size of the target.  Then I would like to switch from my actual Google E-mail authentication (for example: bob@gmail.com) to a different StackExchange one (for example: alice@gmx.com).  I already read . And did this. I have now two logins.  But this blog entry doesn't explain how to initialize the password to the new account (here alice@gmx.com).  Moreover the screen capture of this documentation page shows a "change password" field when I don't have any.  Now that my StackExchange E-mail (alice@gmx.com) is registered as an account to access StackExchange, how could I initialize its password? I hope it couldn't be my password to my Google E-mail.  If not, where is the documentation explaning how this is avoided?  I suggest the page  might be improved so as to clarify this part of an account creation.

I no longer use the service that I originally used to register, and would like to change the service I use to log in, or at least add a second account.  Is this possible? How do I change my login provider or associate a backup method to log in?     For more information, see "" in the .


quick question, I am able to create schematics in EAGLE and other online based tools. But for the purpose of creating basic schematics, i.e. no model numbers, with basic stencil component outlines?  I have VISIO but it does not have all the required shapes, such as op-amps, or is it a case that there is no free option available?

I was going to add a bit of information to my post on a previous day using schematics and some instructions. What programs are being employed for this purpose?  I mostly want to see what others are using and that I can easily use to give descriptive schematics.  In a perfect world, and I know this is a case of me wishing, it would be:   Free. Extremely easy to draw schematics in. Allows simple production of waveforms for the inputs/outputs.


I understand that the gravity has to have a pull greater than the speed of light, but I thought that when gravity pulls light it doesn't accelerate it only blue-shifts it. So then why does gravity only pull light in when it has a g force greater than its velocity?  Also is there any evidence that gravity blueshifts light

In  (ignoring Hawking radiation), why is a  black? Why nothing, not even light, can escape from inside a black hole? To make the question simpler, say, why is a  black hole black?


We have a website that lots of our contents are from other sources and we also have a link to those sources at the bottom of each content, but recently we started to generate content by ourselves, which means we're going to have more exclusive content which is written inside out own company.  There are two questions here:  1- How to let Google clearly knows that those contents are from those sources? (I'm worried about the negative point from Google)  2- How to let Google know this is exclusive content, and different from rest of contents on the website? (any meta-tag or tag?)

This is a general, community wiki question regarding duplicate content.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .     What does Google consider to be duplicate content? Will the way I am presenting my content result in a duplicate content penalty? How can I avoid having my site's content treated as duplicate content?


Table was created with:   CREATE TABLE IF NOT EXISTS `mathsqs` (        `questions` varchar(5000) NOT NULL,  ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;   I have inserted data through PHP using mysqli. To confirm the insertion, I tried SELECT * FROM mathsqs LIMIT 1 on the Windows command line. It shows question marks for non english characters.  How do I see the exact posted data in MySql command line?  Example data I'm trying to handle:     இரு எண்களின் பெருக்கல் பலன் 3375 அவ்வெண்களின் மீ.பெ.வ 15

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


Iam a new learner but i canť  completely understand English films or distinguish between the words when I hear it   And What is the best way to acquire the sense of language?  And is that take too much time?

I've been trying to improve my listening skills for about 9 months.  I realized that I can understand "BBC Radio 4 extra" very well (especially the drama), but I find it's hard to understand "CNN" and most TV movies.   I just want to know your Opinion. Is the British accent easier to understand than the American accent or they are the same?  What is the best way to understand movies? I watch  movies with English subtitles but I think I'm improving my listening skills slowly. Is there any other way to understand movies ?


For my Master Thesis I need to cite patents. One patent is held by a company. By adding the company as an author I get B. F. GmbH instead of the complete name. Same happens, when I enter the company as a holder. How can I force biblatex to print out the whole name?  I use biblatex with chem-angew as style.   \documentclass[a4paper,12pt,twoside]{article} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[ngerman]{babel} \usepackage[backend=bibtexu,style=chem-angew,firstinits=false]{biblatex} \bibliography{Masterthesis}   \begin{document}  wurde als Imprägniermittel für Leder patentiert\cite{Lederimpr}.   \newpage \printbibliography \addcontentsline{toc}{section}{Literatur}  \end{document}   That is the .bib entry  @Patent{Lederimpr,   Title                    = {Process for Rendering Leather and Skins Water-Resistant},   Nationality              = {Deutschland},   Number                   = {DE1960B057177 19600323},   Year                     = {1961},   Holder                   = {(Boehme Fettchemie GmbH)}, }

I want to list a company name in the author field of a bibliographic entry:  @book{CUDA,   author    = {NVIDIA Corporation},   title     = {NVIDIA CUDA Compute Unified Device Architecture Programming Guide},   publisher = {NVIDIA Corporation},   year      = {2007} }   But the entry keeps showing up "N. Corporation".  Is there a way to get the full author name to show up?  I'm currently using the siam BibTEX style.


I couldn't understand how I can get the following result on expansion:  $$3(1-3x)^{-2}=\sum_{n=0}^{\infty}(n+1)3^nx^n.$$ Any ideas?

How can I evaluate $$\sum_{n=1}^\infty\frac{2n}{3^{n+1}}$$? I know the answer thanks to , but I'm more concerned with how I can derive that answer. It cites tests to prove that it is convergent, but my class has never learned these before. So I feel that there must be a simpler method.  In general, how can I evaluate $$\sum_{n=0}^\infty (n+1)x^n?$$


Let $f \in \Bbb C[x_1, ..., x_n]$ be a homogeneous polynomial of degree $d$, and assume that $f=gh$, where $g,h \in \Bbb C[x_1, ..., x_n]$. Is it true that $g$ has to be a homogeneous polynomial of degree $k \leq d$.  I tried to write $$f(\lambda x_1,  ...,  \lambda x_n) = \lambda^d f(x_1, \dots, x_n) = g(\lambda x_1,  ...,  \lambda x_n)h(\lambda x_1,  ...,  \lambda x_n) = \lambda^d g(x_1, \dots, x_n) h(x_1, \dots, x_n)$$  for all $\lambda, x_i \in \Bbb C, \lambda \neq 0$. What can I do next?

Let $k$ be a field.  Suppose I have a homogeneous polynomial $f$ in $k[x,y,z]$. If $f$ is reducible, does it always decompose as a product of homogeneous polynomials? Thanks!


So i made a cartoon squid and i want to add some suction cups, so i hit CNTRL+7 and aligned them to one of the tentacles, but now i need it to stick to the bottom, so i add a shrinkwrap modifier and it makes it flat which i need it to be thick, how can i fix this?  Here is a picture:   .blend file:     I have tried other ways but the suction cups hang over the tentacle and it wont "stick" to the tentacle..i have tried answers that are a duplicate of my question but i get the same results. I have tried latice, and shrinkwrap but to no avail.   I still have this problem.

I have a sphere and stretched. I have made a curve and i want that curve to be shrinkwrap on it. I add the shrinkwrap modifier on to it but it lost the original shape. Its flat on the surface.     How can i get the original shape without going flat on the surface. Any suggestion or help


I cannot solve this simple equation, since I cannot find nowhere how ladder operators works on the magnetic quantum number:   $$\langle m|\hat a^\dagger \hat a+\hat a\hat a^\dagger)|m\rangle$$

I'm studying for a test in quantum mechanics and I'm having a hard time understanding how to use . There are no examples in my text book, only definitions that I can't understand how to use, so I hope you can help me instead.  So, there's an assignment where you're supposed to calculate first order correction to the ground state using ladder operators. In the right answer they say that  $$E_0^1 = \langle 0|H'|0\rangle$$  where does the zeros come from? I understand that they're coming from the wave function $\psi$. But I don't really understand the theory behind this.  Then, after some calculations it's written in the right answer  $$ \langle 0|aa^\dagger a^\dagger|0\rangle +\langle0|aaa^\dagger a^\dagger|0\rangle =\langle0|aa^\dagger a|1\rangle +\langle0|aaa^\dagger|1\rangle$$  What are the mathematical rules of these ladder operators? How did these zeros become ones?  I would really appreciate if someone could help me understand this a little bit better.


I am going to use Poisson regression in my model, but I don't know what assumptions I need to check to verify adequacy of the model. In a normal regression, I had to check Gauss Markov assumptions for my estimates to be BLUE. Do I have to check same assumptions for Poisson? Can I apply tests like White's test, Breusch Pagan test, etc., to Poisson regression? I googled these questions but unfortunately didn't find anything helpful, so if you know good source please share.

What diagnostic plots (and perhaps formal tests) do you find most informative for regressions where the outcome is a count variable?  I'm especially interested in Poisson and negative binomial models, as well as zero-inflated and hurdle counterparts of each. Most of the sources I've found simply plot the residuals vs. fitted values without discussion of what these plots "should" look like.  Wisdom and references greatly appreciated. The back story on why I'm asking this, if it's relevant, is .  Related discussions:


Here are these two SQL queries:  SELECT `o`.`date`, `i`.`description`, `o`.`quantity` FROM `orders` AS `o`, `items` AS `i` WHERE `i`.`itemID` = `o`.`itemID`;   and  SELECT `o`.`date`, `i`.`description`, `o`.`quantity` FROM `orders` AS `o` JOIN `items` AS `i` ON `i`.`itemID` = `o`.`itemID`;   I get one result less with the first one. Can someone explain the difference between the two?

Is there any efficiency difference in an explicit vs implicit inner join? For example:  SELECT * FROM table a INNER JOIN table b ON a.id = b.id;   vs.  SELECT a.*, b.* FROM table a, table b WHERE a.id = b.id;


I was wondering how I might go about removing punctuation from user input and creating a set from the words in the input. So far I have this.  input_set = set(self.entry.get().lower().split(' '))

It seems like there should be a simpler way than:  import string s = "string. With. Punctuation?" # Sample string  out = s.translate(string.maketrans("",""), string.punctuation)   Is there?


I am stuck on this one, do not know where to start. Any hint would be appreciated.  What is the cardinality of $[P(\omega)]^{\omega}$? Is it equal to $|P(w)|$? How do I show that?

I need to find the cardinality of the set $S$ of all infinite subsets of $\mathbb{Q}$.   It's easy to prove $\operatorname{card} S=\mathfrak c$ if you first prove that the cardinality of the set of all finite subsets of $\mathbb{Q}$ is $\aleph_0$.   But is there some other proof for the statement without using the second one (about finite subsets)? Probably there is =)


It's relatively simple to prove that this sum converges by using that $|\sin(t)|\leq|t|$ to get that $|f(x)|<\frac{\pi^2 x}{6}$, but this doesn't give boundedness.  I've tried using  and the approximation $\lfloor t \rfloor \approx t$, but the maximum possible error term is linear in $x$ ($2x/\pi$ if I remember correctly), and I've tried to use the Chinese Remainder Theorem to construct values of $x=\frac{\pi}{2} N$ for which the $\sin(x/n)\approx 1$ for small values of $n$, but I haven't been able to get anywhere with that as the behavior of numbers that are close to $n\bmod 4n$ for lots of $n$ is not very nice. My hunch says that there should be values of $x$ for which "the stars align" and the first few terms are close to $1/n$, where "few" is enough for $f(x)$ to get arbitrarily big, but I'm not sure if there's a way to rigorize this via a probabilistic argument.  For completeness, here's a bit of what I've done so far:  Say it were possible for $\sin(x/n)$ to equal $1$ for every $1\leq n\leq K$. Then  $$f(x) = H_K+\sum_{n=K+1}^{\lfloor x\rfloor} \frac{\sin(x/n)}{n} + \sum_{n=\lfloor x\rfloor+1}^{\infty} \frac{\sin(x/n)}{n}.$$  Using for the first sum that $-1\leq \sin(x)$ and for the second sum that $t\sin(1)\leq \sin(t)$ for $0\leq t\leq 1$,  $$f(x)\geq H_K - \left(H_{\lfloor x\rfloor}-H_{K+1}\right)+x\sin(1)\zeta\left(2,\lfloor x\rfloor+1\right),$$  where $\zeta(s,q)$ is the . It shouldn't be too hard to prove that $\zeta(2,q)>1/q$ (although I don't know of a proof offhand), so this implies  $$f(x)\geq H_K - \left(H_{\lfloor x\rfloor}-H_{K+1}\right)+\frac{\sin(1)x}{\lfloor x\rfloor+1}.$$  If $K$ and $x$ are both *large*, this is asymptotically about  $$\ln\left(\frac{K(K+1)}{x}\right)+C$$  for some constant $C$. Thus, if we could make $K$ grow a bit faster than $\sqrt{x}$, we would be able to prove that $f$ is unbounded.  Unfortunately, $\sin(x/n)=1$ for all $1\leq n\leq K$ is not possible for $K\geq 2$ for modular reasons (specifically numbers that are $1\bmod 4$ are not also $2\bmod 8$). So, we would need to find a threshold $\mu$ as well as a $K$ for which $\sin(x/n)>\mu$ for all $1\leq n\leq K$, and then weaken our bounds accordingly. Or, we could try to use a better bound than $-1$ on $\sin$ for the first sum. I'm not really sure.

For any $x\in\mathbb{R}$, the series $$ \sum_{n\geq 1}\tfrac{1}{n}\,\sin\left(\tfrac{x}{n}\right) $$ is trivially absolutely convergent. It defines a function $f(x)$ and I would like to show that $f(x)$ is unbounded over $\mathbb{R}$. Here there are my thoughts/attempts:   $$(\mathcal{L} f)(s) = \sum_{n\geq 1}\frac{1}{1+n^2 s^2} = \frac{-s+\pi\coth\frac{\pi}{s}}{2s}=\sum_{m\geq 1}\frac{(-1)^{m+1}\,\zeta(2m)}{s^{2m}}$$ is a function with no secrets. It behaves like $\frac{\pi}{2s}$ in a right neighbourhood of the origin, like $\frac{\pi^2}{6s^2}$ in a left neighbourhood of $+\infty$. The origin is an essential singularity and there are simple poles at each $s$ of the form $\pm\frac{i}{m}$ with $m\in\mathbb{N}^+$. These facts do not seem to rule out the possibility that $f$ is bounded; For any $N\in\mathbb{N}^+$ there clearly is some $x\ll e^N$ such that $\sin(x),\sin\left(\frac{x}{2}\right),\ldots,\sin\left(\frac{x}{N}\right)$ are all positive and large enough, making a partial sum of $ \sum_{n\geq 1}\tfrac{1}{n}\,\sin\left(\tfrac{x}{n}\right) $ pretty close to $C\log N$. On the other hand I do not see an effective way for controlling  $ \sum_{n>N}\tfrac{1}{n}\,\sin\left(\tfrac{x}{n}\right) $ - maybe by summation by parts, by exploiting the bounded-ness of the sine integral function? Some probabilistic argument might be effective. For any $n\geq 3$ we may define $E_n$ as the set of $x\in\mathbb{R}^+$ such that $\sin\left(\frac{x}{n}\right)\geq \frac{1}{\log n}$. The density of any $E_n$ in $\mathbb{R}^+$ is close to $\frac{1}{2}$, so by a Borel-Cantellish argument it looks reasonable that the set of points such that $|f(x)|\geq \frac{\log x}{100}$ is unbounded, but how to make it really rigorous? To compute $\lim_{x\to x_0}f(x)$ through convolutions with approximate identities seems doable but not really appealing.


Premise  I saw an interesting example of a machine learning logistic classifier for modeling/predicting sentiment for customer reviews. One of the first things in the example was a note on probabilities. Namely, how many reviews were thought to be positive (user liked the product). It was denoted as the following math notation, which is followed by a quote:  $P(y=1)=.7$     Degrees of belief: "I expect 70% of rows to have y=1 (exact number   will vary for each specific dataset, as each dataset would be a   different subset of the underlying population)   When I think about that, it seems to makes sense at surface level, the math concerning probabilities/conditional probabilities aren't too overbearing, but my intuition hasn't been able to reconcile exactly why this information is important. Assuming two outcomes: y=0 and y=1, P(y=1)=.7 would mean 70% of reviews are positive and 30% are negative. If we have a large enough sample size, we could expect the population values to be in the neighborhood of this. Maybe it's .7 or .5; I don't see how it changes how we estimate our coefficients for the model. To me, it just seems like a fun-fact, like I said, I don't see how I'm supposed to use this information during implementation.  The only thing I could think of is that if P(y=1)=.0001 or some really small number, that would mean we have a noticeable case of class imbalance and that could affect classification accuracy (some models are more robust to class imbalance than others). While this is an important consideration, and would probably merit finding P(y=1), I still can't help but wonder is there anything else...  Question  How can we best utilize the knowledge of P(y=1) in classification?  Further Clarification:  Answers may expand on P(y=1) as it relates to any of the following:   heuristic for model accuracy weights for model model selection

I have a question regarding classification in general. Let $f$ be a classifier, which outputs a set of probabilities given some data D. Normally, one would say: well, if $P(c|D) > 0.5$, we will assign a class 1, otherwise 0 (let this be a binary classification).   My question is, what if I find out, that if I classify the class as 1 also when the probabilities are larger than, for instance 0.2, and the classifier performs better. Is it legitimate to then use this new threshold when doing classification?  I would interpret the necessity for lower classification bound in the context of the data emitting a smaller signal; yet still significant for the classification problem.  I realize this is one way to do it. However, if this is not correct thinking of reducing the threshold, what would be some data transformations, which emphasize individual features in a similar manner, so that the threshold can remain at 0.5?


She doesn't has a book. She doesn't have a book.  Why is the first sentence wrong? We use 'has' with singular, and 'she' is singular.

Does and has both are used with singular pronouns (He has the bottle , He does play cricket , etc) whereas Do and have are used with plural pronouns ( They have the bottle , Do they like cricket? , etc)  But still we use Does with have ( She does have a car ). Why? Shouldn't it be     She does has a car.


Well we know that is is the correct form for singular and are is the correct form for plural, right?  As such "There is a great pizza place in Chicago" would be correct in prose or dialogue as would "No, actually there are many great pizza places in Chicago."  However, I hear and occasionally myself say, "If you go to Gino's, I'd stick to the one downtown, but there's several locations now."  So my question is: Is this tense mismatch an eccentricity of speech, or is there any basis for this contraction of there's in plural?  Are you hungry now?  Edit: My question specifically asks for an irregular usage concern. Of course I know what it's supposed to say.

It seems I put a   Bounty assigned by outside party, two lengthy, reference-citing answers, one "-1" (awarded the bounty), one "-2", two others scored "0" and "-2" respectively, the answers suggesting one or the other is correct, 73 comments and no consensus so far - and me, as the asker, lost without a clue what to think of the answers anymore -  this is no longer "Learners' Level" question, so I thought I'd bring it here and hear what the experts have to say.    Original question:  Plurality of verb depending on plurality of list elements  An edit was suggested to my sentence.     There was were an orange, some grapes, two apples and a small pile of cherries on the plate.   In my native language plurality of the verb always follows plurality of the first element on the list. There were an orange,... sounds awkward to me, no matter what follows up. My simple solution was reordering:     There were some grapes, an orange, two apples and a small pile of cherries on the plate.   But that's not the first time I faced this situation and I'd like to know what the rules of grammar say about that - was my editor overzealous or am I trying to copy rules of my language that don't apply in English?    Someone linked a  for negatives, where the situation is more clear-cut ("There is no..."). Same applies to connection with "or" apparently, per accepted answer there. Still, nothing for "and".  It seems there is a consensus that in that if the verb goes after the list, it will be plural.     an orange, some grapes, two apples and a small pile of cherries were on the plate.   There doesn't seem to be clear consensus for:     On the plate { was | were } an orange, some grapes, two apples and a small pile of cherries   Adding more to the confusion is the abbreviated form: "There's"     One last note. In North America, at least, there is a widespread use of using a singular form like "there is" and "there was", without regard for the subject item or items, and this "there is" is often shortened to "there's":           There's three apples on the table!      Could you please clarify this mess?


I know that if $U$ is an open subset of the complex plane $\mathbb{C}$ and $f:U\to \mathbb{C}$ is a holomorphic function and $f$ is one-to-one, then the derivative $f'(z)$ is different from zero for every $z\in U$.  But how to prove converse of this problem:  If $f'(z)\neq 0,  \;\forall z\in U$, then  $f(z)$ is locally injective?

I am trying to solve the following problem:     Let $f:U\to V$ be a holomorphic function such that $f'(z)\neq 0$ for all $z\in U$. Show that for all $z_0\in U$, there exists a disc $D_\varepsilon(z_0)\subseteq U$ such that $f:D_\varepsilon(z_0)\to f(D_\varepsilon(z_0))$ is bijective.   Atempt:  I am trying to use Rouche's Theorem, but I am stuck on a particular step. Let $z_0\in U$. Since $f'(z_0)\neq 0$, there is a disc $D_r(z_0)\subseteq U$ such that $$f(z)=f(z_0)+(z-z_0)h(z),\quad\forall z\in D_r(z_0)$$ where $h$ is holomorphic on $D_r(z_0)$ and $h(z)\neq 0$ for all $z\in D_r(z_0)$.   Let $0<\varepsilon<r$ to be defined later and fix $w\in D_\varepsilon(z_0)$. To show that $f$ is injective in $D_\varepsilon(z_0)$ is to show that the function $f(z)-f(w)$ has exactly one zero in $D_\varepsilon(z_0)$. But $$F(z):=(z-z_0)h(z)$$ has exactly one zero in $D_\varepsilon(z_0)$, so we might want to apply Rouche's Theorem with $F$ and $$G(z):=f(z)-f(w)-(z-z_0)h(z)=f(z_0)-f(w)=-(w-z_0)h(w)$$ to conclude that $F$ and $F+G$ have the same number of zeros and hence $f$ is injective. But that means that we need to find $0<\varepsilon<r$ such that $|G(z)|<|F(z)|$ on $\partial D_\varepsilon(z_0)$. That is, $$|w-z_0||h(w)|<|z-z_0||h(z)|$$ for all $w\in D_\varepsilon(z_0)$ and $z\in\partial D_\varepsilon(z_0)$.  Can we find such $\varepsilon>0$?  It seems intuitive since if we expand $h$ in a power series at $z_0$, $h(z)=\sum_{n=0}^\infty a_n(z-z_0)^n$, then $$|w-z_0||h(w)| = |w-z_0|\sum_{n=0}^\infty a_n|w-z_0|^n < |z-z_0|\sum_{n=0}^\infty a_n|z-z_0|^n.$$ for $w\in D_\varepsilon(z_0)$ and $z\in\partial D_\varepsilon(z_0)$. But this is of course not a proof.


How do I call a button to perform an action in my code? I know to use action listeners, but what if the button doesn't have a variable name like below?  I'm new to Java, so please be patient with me.   public class Game {     public static void main (String[] args)     {         JFrame frame = new JFrame ("Game");          frame.setLayout(new GridLayout(7, 6));          for(int i = 0; i < 42; i++)         {             frame.add(new JButton()); // This is the part I'm talking about!!!         }          frame.getContentPane().add(new gameBoard());         frame.pack();         frame.setVisible(true);     }   Thanks.

private JButton jBtnDrawCircle = new JButton("Circle"); private JButton jBtnDrawSquare = new JButton("Square"); private JButton jBtnDrawTriangle = new JButton("Triangle"); private JButton jBtnSelection = new JButton("Selection");   How do I add action listeners to these buttons, so that from a main method I can call actionperformed on them, so when they are clicked I can call them in my program?


How do you produce a single bracket in LaTeX? I just want to insert a " [ " without closing the bracket. Is there a way to do this?

I have a very long equation that must be separated into two lines, and it has several pairs of nesting \left \right delimiters. Unfortunately, it seems that they need to be on the same line in order for them to work.  Also I'm using the align environment because I need the aligning functionality. Is there a way to have the size of delimiters automatically adjusted over multiple lines?


I need to pass an IEnumerable and a delegate to my method, and then filter it and return an IEnumerable collection with numbers that pass filter. Func<int, bool> filter = x => x % 3 == 0;   public static IEnumerable<int> Filter(IEnumerable<int> numbers, Func<int, bool> filter) {     foreach (int number in numbers)      {         if (filter.Invoke(number))          {             // add number to collection         }     }      // return collection }  I have tried creating a new collection like this: IEnumerable<int> result = new IEnumerable<int>();  But it is not possible since IEnumerable is an abstract class. How should I create and return this collection? I know that there is a lot of easy ways to do this, but can't find any.

In the  question one of the answers had the following code snippet:  IEnumerable<object> FilteredList() {     foreach(object item in FullList)     {         if(IsItemInPartialList(item))             yield return item;     } }   What does the yield keyword do there?  I've seen it referenced in a couple places, and one other question, but I haven't quite figured out what it actually does.  I'm used to thinking of yield in the sense of one thread yielding to another, but that doesn't seem relevant here.


I have this code that assigns each time different set from the list in the train and test set. I am struggling to understand the code.  df_list = [df1, df2, df3, df4, df5, df6] for i in range(6):     train = pd.concat(df_list[0:i] + df_list[i+1:])     test = df_list[i]   Does it say that it goes from df1[0] all the way until df6[5] and add to this every time one df?  Can you please help me to understanding the code?

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


Let $(a_n)_n$ be a sequence in $\mathbb C$ such that for any sequence $(x_n)_n \in c_0$ the sum $\sum a_nx_n$ is convergent. Show that $(a_n)_n$ is in $l^1$  I have shown $(a_n)_n$ is in $l^p$ for all $p>1$. I was trying to figure out what goes wrong for the sequence $(1/n)$ in which case we get a concrete $x_n=1/(log{ }n)$. So how do I do this general case ?  EDIT: Since there were some comments regarding duplicates of some post let me post an approach I was trying  We know $c_0^*=l^1$ so if $(a_n)_n$ is not in $l^1$ the functional from $c_0 \rightarrow \mathbb K$ given by $(x_n)_n \mapsto \sum a_nx_n $ is unbounded and hence we will get a sequence of sequences say $(x_{n,k})_n$ such that $ |x_{n,k}|<1/k$ $ \forall n$ but $\sum a_{n,k}x_n > \epsilon \forall k $ (after possibly multiplying by $e^{i\theta_k}$ )  Consider the sequence $(z_n)_n$ given by $z_n=\sum_{k} \frac {x_{n,k}}{k}$. Using DCT it is easy to see that $lim_{n\to \infty} z_n =lim_{n\to \infty} \sum_{k}\frac{x_{n,k}}{k}=0 $ and hence $(z_n)_n\in c_0$ but $\sum a_nz_n> \epsilon \sum 1/k$ which goes to infinity. But the catch is in the last part. Any insight will be helpful.

Here is what I know/proved so far:  Let $c_0\subset\ell^\infty$ be the collection of all sequences that converge to zero. Prove that the dual space $c_0^*=\ell^1$.  $Proof$: Let $x\in c_0$ and let $y\in\ell^1$. We claim that $f_y(x)=\sum_{k=1}^\infty x_ky_k$ is a bounded linear functional. Clearly $f_y$ is bounded since $$ |f_y(x)|=\left|\sum_{k=1}^\infty x_ky_k\right|\le\sum_{k=1}^\infty |x_k||y_k|\le||x_k||_\infty\sum_{k=1}^\infty |y_k|=||x_k||_\infty||y||_1. $$ We can also easily see that $f_y$ is linear. Let $x,z\in c_0$ and $y\in\ell^1$ then $$ f_y(x+z)=\sum_{k=1}^\infty (x_k+z_k)y_k=\sum_{k=1}^\infty (x_ky_k+z_ky_k)=\sum_{k=1}^\infty x_ky_k+\sum_{k=1}^\infty z_ky_k=f_y(x)+f_y(z) $$ and for $\alpha\in\mathbb{R}$ $$ f_y(\alpha x)=\sum_{k=1}^\infty \alpha x_k=\alpha\sum_{k=1}^\infty x_k=\alpha f_y(x). $$  Let $\varepsilon>0$ and since $y\in\ell^1$, we know that $\sum_{k=1}^\infty |y_k|$ converges. So there exists $N\in\mathbb{N}$ such that whenever $n>N$ we have  $$ \sum_{k=n}^\infty |y_k|<\varepsilon. $$ Now define the following sequence $x=\{x_k\}_{k=1}^\infty$ as $$ x_k=\begin{cases} \operatorname{sgn}(y_k),&\,k\le N\\ 0, & \,k>N \end{cases}. $$ Thus $x\in c_0$ and   $$ \begin{align} \left|f_y(x)-||y||_1\right|&=\left|\sum_{k=1}^\infty x_ky_k-\sum_{k=1}^\infty |y_k|\right|\\ &=\left|\sum_{k=1}^N\operatorname{sgn}(y_k)y_k-\sum_{k=1}^\infty |y_k|\right|=\left|\sum_{k=1}^N |y_k|-\sum_{k=1}^\infty |y_k|\right|=\left|\sum_{k=N+1}^\infty |y_k|\right|<\varepsilon. \end{align} $$  So we conclude that \begin{equation} \ell^1\subseteq c_0^*. \end{equation} Observe that the above argument also establishes that $||f_y||_*=||y||_1$.  Now let $f$ be any linear functional on $c_0$ and let $\{e_k\}$ be the sequence with a 1 in the $k$-th position and zero elsewhere. Then for any $x\in c_0$ we have $$ |f(x)|=\left|f\left(\sum_{k=1}^\infty e_kx_k\right)\right|=\left|\sum_{k=1}^\infty f(e_k)x_k\right|\le\sum_{k=1}^\infty |f(e_k)|\,|x_k|\le||x||_\infty\sum_{k=1}^\infty |f(e_k)|. $$ Since $f$ is a bounded functional, we must have $\sum_{k=1}^\infty |f(e_k)|$ converging, otherwise $f(x)$ would be unbounded. Thus $\{f(e_k)\}_{k=1}^\infty\in c_0$ and we conclude that  \begin{equation} c_0^*\subseteq\ell^1.  \end{equation} Thus (1) and (2) tell us that  $$c_0^*=\ell^1.$$    QUESTIONS: If we take $c$ to be the collection of sequences that converge to some real number and $c^*$ to be it dual space, I know that $c^*=\ell^1$ as well, but I am not sure how to prove it. Is it enough to observe that if $x\in c$ and that $x\to x'$ then $x-x'\in c_0$, therefore they have the same dual space? I am a little fuzzy here, obviously.  Also, can someone clean up my align environment. I can't figure out how to make it compile properly. The code looks fine on my LaTeX implementation, but it doesn't work here.


I am trying to move one class from an arraylist to another of the same type but associated with a different class. The reason im doing this is that the vehicle is moving from one class (Depot) to another. And I want to replicate that. However I'm finding it difficult to do so.  Here is my code:  if (depotSelection.equals("Lpool")) {     Vehicle v = depots.get(depotNo).getVehiclebyReg(vehicleSelection);     depots.get(0).makeVehicle(v);     depots.get(depotNo).removeByVehicleReg(vehicleSelection);     exit = true;     break; } if (depotSelection.equals("Leeds")) { Vehicle v = depots.get(depotNo).getVehiclebyReg(vehicleSelection); depots.get(1).makeVehicle(v); depots.get(depotNo).removeByVehicleReg(vehicleSelection); exit = true; break; } if (depotSelection.equals("MChester")) {     Vehicle v = depots.get(depotNo).getVehiclebyReg(vehicleSelection);     depots.get(2).makeVehicle(v);     depots.get(depotNo).removeByVehicleReg(vehicleSelection);     exit = true;     break; }   And here is the code to that I am using to remove it:  public void removeByVehicleReg(String regNo) {     vehicles.removeIf(v -> v.getRegNo().equals(regNo)); }   This is the current exception I am getting:  Exception in thread "main" java.util.ConcurrentModificationException     at java.base/java.util.ArrayList$Itr.checkForComodification(ArrayList.java:1042)     at java.base/java.util.ArrayList$Itr.next(ArrayList.java:996)     at DepotSystem.reAssignVehicles(DepotSystem.java:400)     at DepotSystem.depotMenu(DepotSystem.java:166)     at DepotSystem.logOn(DepotSystem.java:123)     at DepotSystem.entryMenu(DepotSystem.java:89)     at Entry.main(Entry.java:10)

We all know you can't do the following because of ConcurrentModificationException:  for (Object i : l) {     if (condition(i)) {         l.remove(i);     } }   But this apparently works sometimes, but not always. Here's some specific code:  public static void main(String[] args) {     Collection<Integer> l = new ArrayList<>();      for (int i = 0; i < 10; ++i) {         l.add(4);         l.add(5);         l.add(6);     }      for (int i : l) {         if (i == 5) {             l.remove(i);         }     }      System.out.println(l); }   This, of course, results in:  Exception in thread "main" java.util.ConcurrentModificationException   Even though multiple threads aren't doing it. Anyway.  What's the best solution to this problem? How can I remove an item from the collection in a loop without throwing this exception?  I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get.


I have Samsung Galaxy Chat B5330 and I was wondering if there is a way to get USB-OTG support on this.     sorry for my bad English.

Some Android devices can act as a USB host, so that you can use other USB devices attached to them. For instance, browse or import the photos stored on a camera from your phone, or copy files onto a USB memory stick attached to your tablet, plug a full-size USB keyboard or mouse into a tablet, or use an external GPS or wifi device.  How can I tell if my device can do this?


I'm following a lightsaber tutorial. A video is loaded as an image texture material to a plane that then is set to always face the user/camera. A plane with a emission material is created and then I go frame by frame to line it up or use motion tracking with a stick I'm holding in the video.(I'm trying both just for fun.) The problem is that the video frames are changing position with around 1 or 2 frames ahead or after at random.(So I can't just change the video offset.) When loading the video into a movie clip editor the video lines up correctly. The video cant be loaded as a background video because this removes the emmision from the saber. I'm rendering in EEVEE. The video is set to auto update the video frame when a new frame is selected.I set the frame count high for the video (around 6000, later 2000 but did no difference). Tell me if you need any more information.

I am trying to render an edited clip at 23.98 fps for use with motion tracking in a different project that shares the same frame rate. However, when I go to the tracker when the rendered clip is loaded, some of the frames show up twice in a row, thus throwing off the whole track. Any idea why this is happening?


Which is correct "I wished I was a painter" or "I wished I were a painter"?  I've seen in several places that "I wish I were a painter" and "I wish I was a painter" are both correct (e.g. ), but I have not been able to find a solid answer to past tense "wished".

Possible Duplicate:          Which one is the correct form: "Wish I was here" or "wish I were here"? I've heard both of them many times but I don't know which one is correct.


I will start by saying that I have nothing against any individual or company making a profit out of goods, services or intellectual property they produce. However, I do not like the fact that publishing houses, such as Elsevier (just to name the largest one), make a profit out of the voluntary/non-retributed work of others. By this, I refer to the fact that the core product these journals are selling are scientific articles written by others, based on research funded by others, and with a quality control (peer review) carried out by others with no cost to them. Then, research and academic organizations pay these publishers large amounts of money in the form of subscription fees to gain access to content the community provides for free.  Because of this, I have decided to, whenever possible, I will try to avoid submitting my articles to for-profit publishing houses and will try to rely as much as I can on the journals published by scientific societies. In my field (physics, materials science, chemistry) this is not necessarily a problem, since the APS, AIP, IoP, ACS, RSC, etc. publish a number of reputable journals that can suit my needs. I understand that other authors might not have a choice, or might simply choose to also publish with for-profit houses. This might force me to publish at a venue not of my liking when I coauthor a paper with people interested in sending the collaborative work to such venues. This is not a huge problem for me.  The case of peer review is more complicated, because refusing to review papers sent to me by a for-profit house does not only hurt the publishing house, but also the authors that submitted the paper, who are precisely the community whose interests I am attempting to protect by taking my overall stance against publishing corporations.  By submitting my work only to specific journals I am not actively engaging in any action that could be considered offensive by the for-profit journals and their editors. However, by refusing to review their papers I am directly saying "no" to the editor who sent me the work. I would like to know how I would be hurting my career by "soft boycotting" for-profit journals in the cases a) not submitting there, b) not agreeing to review their papers and c) both.

I fully support the Elsevier boycott, and came from mathematics (BS and MS) into my current PhD program in an engineering subdiscipline. I'm finishing up my PhD now and starting a post-doc soon.  I've already refused to review an article a few years ago for an Elsevier journal, and the editor seemed quite angry about it.  Once again I have been asked to review an article for an Elsevier journal, only this time the journal editorial board has a prominent researcher who I have had personal contact with, is a recently retired Emeritus Professor from my department, and if he became angry about my refusal he could potentially harm my career.   Does anyone have any specific examples of, or even better statistical data showing that boycotts of Elsevier journals had negative career impacts on early career/junior scientists?


I'm trying to clear parents of some mirrored and seperated objects and even if I clear parent while keeping transform, the scale and rotation of the objects still change and warp the objects which destroys all the work. I don't quite understand how to get this to work.

When I select the Mesh (scaled by empty), hit Alt+P choose "Clear Parent and Keep Transformation", it clears parenting, but transformation is not kept.  Is there any visible reason why the operator is not working on this specific model (blend file, collection 02)? What kind of hidden setup can cause this issue?  For now it seems like different rotation (mesh and empty), cause the issue. If empty and mesh is the same rotation (collection 01 and 03) Alt+P works fine. Since Empty is rotated it fails (see collection 02).


I am in class 10 and I have just read the electromagnetism chapter. They always keep on saying that electricity produces magnetism! but how!? We know electrons move, but how do they produce something that can exert a force on something metallic far away from those electrons? I have tried to read about it on wikipedia but I am not able to understand the complicated terms! Please answer in such a way  that it will remove all my confusions!

I'm tutoring high school students. I've always taught them that:     A charged particle moving without acceleration produces an electric as well as a magnetic field.   It produces an electric field because it's a charge particle. But when it is at rest, it doesn't produce a magnetic field. All of a sudden when it starts moving, it starts producing a magnetic field. Why? What happens to it when it starts moving? What makes it produce a magnetic field when it starts moving?


If I have a p-value of 0.01 on a statistical test, does that mean the probability of my hypothesis being wrong is 1%?   If not, why not?

After taking a statistics course and then trying to help fellow students, I noticed one subject that inspires much head-desk banging is interpreting the results of statistical hypothesis tests.  It seems that students easily learn how to perform the calculations required by a given test but get hung up on interpreting the results.  Many computerized tools report test results in terms of "p values" or "t values".  How would you explain the following points to college students taking their first course in statistics:   What does a "p-value" mean in relation to the hypothesis being tested?  Are there cases when one should be looking for a high p-value or a low p-value? What is the relationship between a p-value and a t-value?


I would like to be logged into 3 different gmail accounts at once.  I thought that command/switch combination would accomplish this by opening new browser windows with separate incognito mode:  "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" -incognito --new-window https://mail.google.com   Clicking on the shortcut will launch a new window, and it will be incognito, and it will be directed to gmail. I then log in, and then rerun the shortcut and log in with my next account  But, the 2nd window that launches is logged in as my 1st user (why is chrome sharing cookies accross incognito windows - scary!) If I change the log in inside session 2, I then lose the 1st session's log in!  I need the igcognito windows to each be in their own session. How can I acheive this?  Any ideas?  Thanks  (Note: I actually want to acheive this with an intranet site - not gmail, but I am using gmail to illustrate my point)

When opening new Internet Explorer window, a new browser session is issued. Therefore you can login with two different accounts on the same service (let's say ). The same does not apply when opening a new tab in the same window in Internet Explorer.  How can I get a new browser session when opening a new tab or window on Firefox?  How about Google Chrome?


I frequently notice I forgot to add a change or made a syntax error immediately after creating a new commit. In these situations I always:  do the right thing(TM) git commit filename -m "fix" git rebase -i HEAD~2 jxxxrf:wq  Is there a shorthand to combine steps 2, 3 and 4 into one?

I wrote the wrong thing in a commit message.  How can I change the message? The commit has not been pushed yet.


I am developing a website in  and am looking for the appropriate front-end and back-end plugins to crop, rotate, and resize images. I have enough experience on Stack Overflow to know that such a question is not appropriate for that forum. What would be the appropriate place to ask for help with what plugins and libraries to use on a project?

Where in Stack Overflow can I ask, which software is best suitable for specific purpose? For example, a good software which is free for fashion related. The application should be able to show a preview how a person looks in different hair styles and eyeglass frames etc.


When I look at "Meta Stack Overflow" , I see many users asking good and bad questions, but I noticed that users asking bad questions who got downvoted don't seem to lose any reputation at all. Is it normal or do the downvotes and upvotes in this need to be validated by a moderator?

I noticed that the reputation from the main site carried over to meta on Gaming (at least the first upvote), I guess that doesn't work the other way around, right?  Is it then impossible to have a meta reputation higher than the site reputation?


She may/might be honest.   This sentence already has the meaning that      She may/might not be honest.   1. Why do we sometimes say:     She might and/or might not be honest.   2. Which conjunction is (more) correct: "and" or "or"?  So, the question is not on when to use "might" and when to use "may", it is about why each comes along with its negation, and what difference that usage makes to the meaning. Is it just about emphasis?  The second question is about the conjunction that should be used between them: "and" or "or"? Both versions  are used frequently on the web.

I may not be coming in tomorrow...    I might not be coming in tomorrow...       When should I use "may" and "might"?


I found this example in Mozilla developers page, but can't understand the concept.     function outside(x) {        function inside(y) {           return x + y;        }        return inside;     }     fn_inside = outside(3); //returns inside(y) -- from firebug     result = fn_inside(5); // returns 8      result1 = outside(3)(5); // returns 8   It seems like 3 is somewhat stored in the function 'inside' and during the second call adds it with 5 and returned 8.  And how does the second call to outside (outside(3)(5)) returned value (8) instead of the inner function (inside) unlike the first call?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


Everything except for the main method was written by my professor, so supposedly it should work. For reference, I'm pretty sure this code is supposed to remove any repeating letters from a string, turning "blaahhhblah" into "blahblah". This code compiles with no errors or warnings (compiled under the 1999 standard) but gives a seg fault when I run it and I have no idea why. I feel like there's probably an obvious answer to this, but we don't use a book for this course and the professor hasn't taught very well so I'm lost.  void g(char* a) {   char* b = a;   while(*b) {     while(*a == *b)       b++;     a++;     a* = b*;   } }  int main() {   char* x = "blaahhhblah";   g(x); }

The following code receives seg fault on line 2:  char *str = "string"; str[0] = 'z';  // could be also written as *str = 'z' printf("%s\n", str);   While this works perfectly well:  char str[] = "string"; str[0] = 'z'; printf("%s\n", str);   Tested with MSVC and GCC.


The idea came from a now-deleted answer to another question (dealing with why people would/wouldn't use household cleannig spell).  In a typical fantasy RPG, spell casters are frequently limited in how many spells they can cast.   Usually this is implemented by giving the spell caster a finite amount of something called "mana" points, and casting each spell subtracts a certain amount of mana points from the caster (usually more complicated/powerful spells cost more points).  Is there a concept in Potterverse that a spell caster is limited in how many spells they can cast by some limited reservoir of a resource necessary for casting the spells?   (obviously, not implemented by mana points :). But perhaps a mention in canon that someone was utterly exhausted by casting many spells and couldn't cast more).

Often in fantasies involving magic casting spells requires a certain physical or mental toll on the caster. I don't recall any mention of spells being physically or mentally taxing in the Harry Potter universe.  Does this mean they can cast an unlimited number of spells in a given day without any negative effect to themselves?


I have recently installed Ubuntu on my system to start learning Linux.  My boss has challenged me to install Canon lbp 2900b on my computer. I have Googled many pages but none of them are working fine for me. Many of the commands are giving me some dependency errors.  I'm not much versed with programming knowledge, please can anyone help me with simple instructions and tutorial.

I downloaded Linux CAPT driver V2.60 from Canon and installed both .deb packages, which were listed under the 64bit folder with Ubuntu Software-Center. My Canon printer still won't be recognized. Is there anything else I have to do? My printer is connected over USB.  Ubuntu would make a great replacment for my office, but unfortunately without printer support I will still rely on Windows.


Most of us have seen microwave ovens with metal racks or shelves, which challenges the common notion that you can't (safely) put metal in a microwave oven.  What's going on here?  Is it a matter of these shelves being made of a specific metal (if so what are the properties that allow it to be used in a microwave oven?) or of being placed in just the right place in relation to the waves that will be emitted, or something else entirely?  If it is a matter of using just the right metal (or alloy), then which metals are okay to use in a microwave oven?

I heard that electrons accumulate at points on metals, and this clearly explains the arcing phenomenon, but how does a microwave make an electron imbalance on the fork?


I need to voltage boost my battery voltage 3V to 12V DC to power cheap RF module transmitter. The boost voltage will last until I transmit 3 or 4 bytes of serial data. Roughly 5ms time.  I read  wonderful article by olin lathrop & trying to understand it.  I need 3V to boost upto 12V. 50mA current is more than enough. Supply battery is CR123 3V Cell.  I have some questions...!  1) Where is the boosted output voltage calculation? How to calculate it?  2) What component values need to change in the attached diagram to get 12V/50mA?         – Schematic created using

I am trying to build a DC-DC Buck-Boost Converter using  basic schematic and an Arduino with the analogWrite() function as my PWM generator. I only want to step up 2.4-3V to ~5V. If it's just the capacitor and no load, the converter works so good that I have to switch it off after a few seconds since the voltage I measure on my capacitor is exceeding the capacitor limit. However, when I connect any load to the capacitor(for example a motor or a resistor) my voltage drops to a really low value(0.1-2v) and stays that way no matter what frequency PWM signal I send to the transistor using Arduino. I really tried but couldn't find the cause of the problem. Is it because I have two grounds, the battery pack one and the Arduino one? Is it because of the inductor(I tried using a smaller, 45uH, torroidal one but couldn't get any better results)? So what am I doing wrong?   I only expect to draw 500mA of current at 5 volts at the output side, and according to  calculator my inductor and transistor should be fine.  Components: 100uF 35V electrolytic capacitor, 200uH inductor, BYW29 rectifier diode, TIP 120 power transistor, 1k resistor    A schematic of the circuit or at least how it is supposed to look. Maybe I miswired something? The resistor is to represent  the load, the value doesn't matter since my problem persists at any value but the multimeters "infinite" resistance.   This is how my circuit looks   I used one coil of an old transformer as my inductor    However I also tried this inductor


Let $F$ be a field. Why is $\frac{F[x]}{(x-1)}\oplus \frac{F[x]}{(x-1)}$ not isomorphic to $\frac{F[x]}{(x-1)^2}$ as $F[x]$-modules?  My initial thought was to say the direct sum is generated by 2 elements but the other one is generated by 1. Is there any truth to this line of thinking?

Need help with this question:     Let $R$ be a PID, and let $\pi\in R$ be prime. Is it ever the case that $$R/\langle\pi\rangle \times  R/\langle \pi\rangle$$ is cyclic as $R$-module?    So my attempt is horrible, here it goes   Proof: Since $\langle\pi\rangle$ is a prime ideal, $R/\langle\pi\rangle$ is either isomorphic to R or $0$ (Since every prime ideal is either zero or maximal in a PID.) If it is 0, this is trivially cylcic. However if it was R, then $R \times R$ is cylic if and only if R is cyclic.  So this is my horrible attempt, I just need help getting pointed to the right direction.


I have a directory with *.txt files.   How can I list the txt filenames that are still having non-unix eol's? So windows and mac eols.

I need to periodically run a command that ensures that some text files are kept in Linux mode. Unfortunately dos2unix always modifies the file, which would mess file's and folder's timestamps and cause unnecessary writes.   The script I write is in Bash, so  I'd prefer answers based on Bash.


how does one add more more social links and their associated icon/symbol(e.g codeplex, bitbucket) in moderncv.   I tried to include this:       \ifthenelse{\equal{#1}{codeplex}}  {\collectionadd[codeplex]{socials}             {\protect\httplink[#3]{www.codeplex.com/#3}}}     {}%   but nothing seems to work.

How do I add extra links to the footer of a moderncv document that are not covered by the default commands?


I need to prove that $5^n-1$ is divisible by $4$, $\forall n \in \mathbb{N}$.  So for the inductive step I know that:  $$5^{n+1} -1= 5\times5^n -1$$  but how do I get from there to:  $$(5^n -1) + 4\times 5^n?$$  (That is the solution to the exercise.)

Prove by induction that $5^n - 1$ is divisible by $4$.   How should I use induction in this problem. Do you have any hints for solving this problem?  Thank you so much.


Suppose I'm flying through the air after a jump, and grab the end of a rope that's hanging straight down. At the moment I grab the rope, I have a certain velocity vector $v$ and am only under the influence of gravity. What kind of trajectory do I follow after grabbing the rope?  For instance, suppose the vertical component of $v$ is negative (downward). Does the rope just instantaneously zero out the vertical component of $v$, while leaving the horizontal component intact? If the vertical component of $v$ is positive, do I continue to move in a parabola, unaffected by the rope until it becomes taught?

When two bodies, free of movement, are linked by a physical constraint (a maximum distance between them) how do their masses and velocities influence each other? Which formula with theses parameters gives the force applied by one of the two on the other?  For example : I have two box (grey and red) that are next to each other attached by a rope of maximum length L, the grey one jump following the yellow curve C and i'm trying to get the equation to find the force applied to the red box when the distance between the boxes reach L. V is the velocity when the gray box reach the red circle. It would probably split into the radial force and the tangential force depending on the angle. I guess the answer would probably work for every position on the red circle.  I tried to read about pendulum but there was only the gravity taken into consideration, and it kinda felt like the tension was vertical. There might be an answer for me in one ticket but i just couldn't find it.


I need a way to keep auto-increment counter between mysql service restart.   As docs states by default after restart mysql autoincrement counter start from max(id)+1. How can I keep the last autoincrement value?  This is a big problem for me. I'm using envers to keep entities audits. I get as many errors as many "last rows" I delete.  Suppose I'm starting insert data into an empty table. Suppose to insert 10 rows. Then suppose to delete the last 8. In my table I will have as result 2 entities, with id 1 and 2 respectively. In the audit table I will have all 10 entities, with id from 1 to 10: entities with id from 3 to 10 will have 2 action: create action and delete action.  auto-increment counter is now setted to 11 in main table. Restarting mysql service auto-increment counter goes to 3. So if I insert a new entity, it will be saved with id 3. But in audit table there is already an entity with id = 3. That entity is already marked as created and deleted. It result in an assertion failure during update /delete action because envers cannot handle this inconsistent state.  Thanks

I recently read that because of how InnoDB recalculates the AUTO_INCREMENT value when the server restarts, any records on the high end of the ID list may have their IDs reused.  Normally, this isn't a problem, because when a user is deleted everything associated with the ID is deleted from other tables too.  But I'm deliberately leaving their forum posts orphaned, labelled as "Posted by =User #123=", so that past conversations are retained. Clearly, should an ID be reused, this will be a problem.  I've never had this issue before because there were always enough new users to make it unlikely for an ID to be reused in this way. However on my new project signups are rare and inactive user deletions frequent (especially since the "Open Alpha" accounts only last for three days as a preview), and such ID reuse has happened three for three now.  I have "fixed" the issue by saving the correct value for AUTO_INCREMENT elsewhere and using that instead of relying on the internal value. Is there an actual way to have InnoDB remember the actual last value?


Say I have the following in R  rm(list=ls()) set.seed(1000) n<-20 x<-rnorm(n, 0.5,1) y<-rnorm(n, 0.5,1) type<-rep(2,n) df1<-data.frame(x,y,type) x<-rnorm(n, -0.5,1) y<-rnorm(n, -0.5,1) type<-rep(5,n) df0<-data.frame(x,y,type) df<-merge(x=df0,y=df1,all=T) plot(df$x,df$y,col=df$type)     Now as you can see I have classes that overlap -- say the cost of classifying the red class incorrectly is 10 times the cost of classifying  the blue class incorrectly.  Say I want to use a logistic regression -- how would I do incorporate the cost into my logistic regression model?

I want to make my classifier prioritise finding true cases (1) even if that means that a lot of the false cases (0) are also classified as true.  Specifically I wish to find the weights to my features that gives at least 97 % of my true cases as true and as a small fraction as possible of my false cases as false.   What should I be looking for in a logistic regression setting? Of course I can just adjust the intercept but I assume that there must be some better way?


This is more of a question about philosophy of mathematics. There is an apparent circularity in set theory and logic, in the means that we use set theory to define model theory, and we use results from model theory for proofs in set theory. And, analogously, we use set theory to prove facts from logic (unique readability, for example) and we define set theory using logic. I feel that we can reduce all this notions to a single syntactical idea of logical consequence, and from there we can define things in a non-circular way. However, I can't seem to make this notions all fit together in a logical, foundational manner. Does anyone know of an article or book that addresses this issue?

I wonder about the foundations of set theory and my question can be stated in some related forms:   If we base Zermelo–Fraenkel set theory on first order logic, does that mean first order logic is not allowed to contain the notion of sets? The axioms of Zermelo–Fraenkel set theory seem to already expect the notion of a set to be defined. Is there are pre-definition of what we are dealing with? And where? In set theory, if a function is defined as a set using tuples, why or how does first order logic and the axioms of Zermelo–Fraenkel set theory contain parameter dependend properties $\psi(u_1,u_2,q,...)$, which basically are functions?


I have the following string:  DB Results:
ripster.ultima
raghav.jhavar

   I want to extract "ripster.ultima" and "raghav.jhavar", so I used the following regex:  (?<=
)(.*)(?=<\/b><\/center>)  Now, this works in some cases, but not in all:   In the link above, the first example is a single line. When I put in a single line, it does not select the individual strings. However, if its separated by a new line as seen in the second example, the strings I want are highlighted.   How do I get the strings in the first example?

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


I'm trying to solve this     $$\int_{0}^{\infty} e^{-4x^2}dx$$   I saw how $\int_{\infty}^{\infty} e^{-x^2}dx$ it's done and how it covers the whole plane, then I assume that from $0 \ to \ \infty$ it's the right part of the plane, My problem comes when I try to cover the first and the fourth quadrant of the plane, I know that in polar coordinates $0\le r \le \infty$, but      What about $\theta$ for this case? How $\theta$ moves in order to cover the right half of the plane?

How to prove  $$\int_{0}^{\infty} \mathrm{e}^{-x^2}\, dx = \frac{\sqrt \pi}{2}$$


Ubuntu server system (no X installed) that runs several networking daemons.  It's been headless for years but I recently attached a monitor to it and installed some cli monitoring utilities (glances and pysensors) as this server is also my NAS gateway.  Been on this horrific easter-egg hunt searching for how-to disable the screen-blanking / powersaver mode for the terminal.    I'm hesitant to remove acpi as a package because of unknown/future interdependencies.  Somewhere, there's some obscure config setting that will prevent the monitor from blanking.  I've disabled the sleep option in the monitor's firmware - and, of course a key-press on the kb will awaken the screen...but not sleeping at all is optimal.  thanks...

How to disable blank screensaver on Ubuntu Server?  There's no desktop or X, only console (command-line interface).


I'm attempting to get a modded Minecraft Java Edition server up and running, but my friend joining me keeps getting the following error:  io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection timed out: no further information:   I also get the same error if I attempt to join myself not using 'localhost.'  I've forwarded the port 25565, allowed it through my firewall on both TCP and UDP, allowed all copies of Java platform SE Binary (i have many for whatever reason) through private and public, and all Minecraft executables through the firewall, but in case that wasn't enough I then turned off my firewall entirely, reinstalled Minecraft and did it all over again. My friend has the exact same mods as the server and I, the same Minecraft version as the server and I, but still gets this error. How do I fix this?  EDIT: It also does not work in vanilla.

I am getting the following error when I try to connect to a Minecraft server:  This is all servers, not just one. The error says:  io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: no further information: Version 1.12  I've tried:  Restarting Minecraft Restarting Computer Uninstalling and Reinstalling Mincraft Uninstalling and Reinstalling Java Altering Firewall Restarting Internet I've messed with my port, made a second windows account, reset netsh winsock Checked hosts Made a new WINDOWS account  The overlay in the bottom right is Geforce's Overlay for game capturing. I don't have any mods installed. A Mojang support ticket wouldn't help. Im desperate.


The definition of the exponential with integer exponents is straightforward to define: $x^n=\underbrace{x\cdot\ldots\cdot x}_{n-\text{times}}$.  These days I've been thinking about the formal definition of the exponential with real exponents.   My question:     What is the definition of $a^{b}$, where $a,b\in \mathbb R$.

We all know that $2^5$ means $2\times 2\times 2\times 2\times 2 = 32$, but what does $2^\pi$ mean? How is it possible to calculate that without using a calculator? I am really curious about this, so please let me know what you think.


But my reviewing stats show 82 edit reviews:    Is it a bug or I misunderstood something?

The counter for the Copy Editor badge progress is off by double digits in my profile. As you can see, I've had 100 edit suggestions accepted, but the progress counter shows 75:    Also, you can see yet a third count in my activity section:    I actually noticed the discrepancy a while back, but I was curious the badges would end up being based on the real count or the incorrect count in the progress stats, so I decided to wait until I reached 80 before posting on meta. When I reached 80, I realized that the badge progress counter is decremented when a post you've edited is removed, so I waited until I was over 80 not including removed posts. Then I waited until I was well above that threshold, just to be sure.   Based on the rep reversals in my profile, only 9 of the 100 posts I've edited have been removed. The 98 in the activity log makes sense, because I've seen that those entries go away when the post they refer to is deleted, so the number is the total number of edits (accepted and rejected) minus the number removed. There's one extra (100 approved + 6 rejected - 9 removed = 97, but the activity section's counter shows 98), but I'm sure there's a simple and logical explanation.  However, I can't explain why the badge progress counter only shows 75 when I have 91 accepted edits that haven't been removed. I'm not sure how rollbacks affect the count, but I find it unlikely that more than 16 of my edits have been rolled back. I'm not aware of any except one that I rolled back myself after realizing it was a mistake, even though it was approved.  Also, as of this writing I don't have the Strunk & White badge, even though I passed 80 in the number of approved edits minus the number removed about a week ago. So, it appears that the badges are based on the same query that produces the flawed badge progress counter.  [I edited the title to make it clear to the tomato-throwers that this was intended as a "I noticed a discrepancy, why don't the numbers add up?" question, not a "Hey, no fair, where's my badge??" question. The discrepancy was explained in the accepted answer.]


Popup with message "You haven't voted on a question in a while. Questions need votes too." is displayed so shortly and dissapears so quickly, that I managed to read and understand, what it says, after about fifth attempt or so. Though, I think, my English is quite good.  People with worse understanding of English simply won't read / understand, what this message is saying.  If I'm not mistaken, this popup uses the same mechanism as the one used to display "Thanks, we'll take a look at it". But -- if, again, I'm not mistaken, the second one is displayed noticeable longer.  It there any reason, why this -- kind important -- message, telling people, that they should vote also on question, is displayed so shortly?

I recently got warnings just after having upvoted an answer. It said something about the fact that I haven't voted for a question for a long time and that questions need votes too.   The problem is that it disappeared so fast that the first time I could not read it at all. Well, ok, to be honnest I could probably read the 2-3 first words :-) but not more.  Could not this message stay a little longer on the page ?


I know just enough networking to be dangerous. The nitty gritty low level details of NAT are not something I am particularly knowledgeable about.  I accidentally found myself in a discussion earlier today about placing a bunch of our nodes behind a NAT Gateway. (1 public IP address and X private LAN addresses). I called up the 16 bit limit to source and destination port fields in the TCP protocol, ( - page 15) and mentioned that it would limit us to some 65,000 connections (65536). -- I am not so confident about that answer anymore. Can you help me with some details?  I understand that an incoming port (server port) on our side can accept as many connections as there are sourceIP x SourcePort combinations. Let's discount those for the time being and focus on connections originating in the LAN, traveling through the NAT Gateway, and ending on a random host at a random port.  On a normal [Linux] system, outgoing connections I believe are limited to 1 per port per Source IP. If we pretend that we live in a simple world where each system only has 1 IP address, then a 'normal system' would be limited to an absolute maximum of 65536 connections.  1) In TCP is a single source IP limited to 65536 MAX theoretical outgoing connections?  2) Or is the limit actually 65536 connections for each Remote Host?  2) [Written another way]: Can the same source port be used for a different remoteHostIP:RemotePort combination?  For example: (Is the following OK?)  Source IP   |Source Port |Remote IP|Remote Port    192.168.0.20:36500   -->    8.8.8.8:23 192.168.0.20:36500   -->    8.8.4.4:23   3) Are the answers to questions 1 and 2 different for a ...'not normal system' [Cisco router acting as a NAT Gateway]?  Ex: A specialized networking device that has one public facing IP and up to ~65,000 Lan IPs [or more] behind it? Is there magic at place or is the answer to question 2 just always: yes? (or no)  4) The above questions all assume a stateful TCP connection. Is the story any different with a stateless conection like UDP?  And Ultimately:  5) Will our LAN be limited to 65536 (or some other theoretical limit) concurrent connections to the outside world through a single public IP address?  Thank you! :)    For purposes of this question, we are behind very BEEFY AND BRAND NEW Cisco Nexus gear (7000 series I think). It may be better to ignore memory/etc limitations unless they can be specifically quantified.

If there is a limit on the number of ports one machine can have and a socket can only bind to an unused port number, how do servers experiencing extremely high amounts (more than the max port number) of requests handle this? Is it just done by making the system distributed, i.e., many servers on many machines?


I don't have last name in any of my id proof. So while booking tickets my dad has given 00 in place of surname. Because it was mandatory to fill last name. Will it create any problem for me?

I have booked tickets for my parents to visit Mauritius for a week and my mom's passport (given name is xxxx) doesn't have surname, so in the e-ticket form her name has been printed as "Mr xxxx". I have spoken to the travel agency and Air Mauritius, but didn't get any information regarding the issue.  Can anyone please tell me if there might be a problem boarding the flight?  I am very anxious right now since its their first international flight.


I'm trying to decrement a number and then print it, all outsourced to two methods.   Why does the method decrement(number) return 10 and not 9?  public static void main(String[] args) {     int a = 10;     printB(a); }  private static void printB(int number){     decrement(number);     System.out.println(number); }  private static int decrement(int b){     b -= 1;     return b; }

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


I am a relatively newer Python developer, but I come from a Java background. In Java, there is one-line Boolean checker/assigner (for lack of a better term):  int result = (x)?y:z;   I am trying to use a similar approach in Python, but I am not sure whether this structure exists. Is there a way to declare a variable, check whether a condition is true and assign it to one of two values without using if/else?

If Python does not have a ternary conditional operator, is it possible to simulate one using other language constructs?


I tried to search for a folder in its parent folders instead of its child sub-folders (usually any search bash command will do). I need to know whether any reverse alternative for any search commands actually exists.

I'm nested deep in a file tree, and I'd like to find which parent directory contains a file.  E.g. I'm in a set of nested GIT repositories and want to find the .git directory controlling the files I'm currently at. I'd hope for something like  find -searchup -iname ".git"


I've a table that allow me to add or remove row. <button data-action="add-item">Add line</button>

             Line	             Element

                              1             	                              <input type="text" name="element[]">             	                              <button data-action="remove-item">                     Remove                 </button>

             	             Total:	                              <input type="number" name="EST_ItemsSum">

  My issues is are:  How can I insert the line number in front of each line ? How can I remove the line when I click on the Remove button (dynamic way with event propagation) ?  Here my JS code: // Add item $('[data-action="add-item"]').click(function(){     $('table > tbody > tr:first').clone().find('input').val('').end().insertBefore('table > tbody > tr:last'); })  // Remove item $('[data-action="remove-item"]').click(function(){     $(this).closest('tr').remove(); })

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I am learning some discrete mathematics and stuck on following problem : Let $G$ be a graph with $100$ vertices prove/disprove that there are two vertices with same degree. I know that for a given vertex  $v$ there are $99$ choices for a neighbor of this vertex hence degree  ${\rm deg}_{G}(V) \le 99$ But after this I don't know how should I proceed ?

I want to prove this claim using contradiction:     Let $G$ be a simple graph with $n$ vertices. Prove by contradiction that $G$ has two vertices having the same degree (Consider the vertex of smallest degree and vertex of largest degree).    I think I know where to start. The vertex of the largest degree is $n-1$ in this graph and the smallest is 1. How can I use contradiction to prove the statement above? I studied the proof of this using pigeonhole but I wanna use contradiction this time.


I have this code where i get multiple data from database using ajax jquery and php. which works and displays the data in the webpage but the problem is that the links in the data (like  tag link) isn't responding or showing any sign of a click event even after i add a click event. this is my code before HTML

  JQUERY AJAX getProducts(); function getProducts() {     $.ajax({         url: "adminbked/getData.php",         method: "POST",         data: {             action: "getProducts"         },         success: function (data) {             $(".pro-bd").html(data);             // This is the dataTable plugin             $("#proTable").dataTable();         }     }) }  getData.php <?php  require "../../db/dbconn.php"; $POST = filter_var_array($_POST, FILTER_SANITIZE_STRING);  if(isset($POST['action']) && $POST['action'] == "getProducts") {     $status = "Yes";    $sql = $conn->prepare("SELECT * FROM shopping_products_info ORDER BY productId DESC ");    $sql->execute();    $result = $sql->get_result();    $html = '';    while($row = $result->fetch_assoc()):         $html .= '

';  endwhile;  echo $html;  }   This is the click event $(".bt-dlt").click(function () {    var id = $(this).attr("id");    console.log(id) })  Please is there anything i did that makes the link not clickable. what should i do.


This video  talks about the background radiation which we can observe today. It's from the beginning of the universe and has traveled so long that the expansion of the universe has changed its wavelength to microwaves, instead of visible light.  The way the video describes it i would think that as some point the waves from the background radiation would have to not be observable anymore, because they have been absorbed by an object along the way. Could they lose energy and not only their wavelebgth gets super long, but also their amplitude very low? And finally: will the universe at one point expand so fast (faster than light speed) that the background radiation waves cant ever catch up to us and we wont be able to observe them? If it ever should cease to be observable by us, when would that be approximately?  As i stated in the title: Will the background radiation get "dimmer"? If so when will it be "turned off"

Will we ever reach a point where all the light that was set free by recombination finally reaches us from our point of view and the CMB stops "shining" for observers on Earth?


Starting from today the Google Hangouts panel in my Gmail tells me that I should join Google+ to use Hangouts. Is there a way to revert the plugin to the old Google Talk plugin in Gmail?  (Please note that the plugin is completely useless this way, showing me only that message, therefore I can't really use it to turn it back.)  EDIT: screenshot (sorry that I couldn't make it to be English)

I don't like the new Google Hangout integration with my gmail web app.  It's too busy, too much color, and too hard to see what status people are.  In short, get off my lawn.  Can I get the old Google Chat interface back?


I just started to try and learn Java and in making a program to practise I have run into an issue and was hoping smoeone could help me.  I'm sure it is something very basic but I can't spot it.  I have a '+' button that when clicked add the value of a text field into an integer variable.  Below is the code:     private void cmdPlusActionPerformed(java.awt.event.ActionEvent evt) {                                                 // TODO add your handling code here:         intTotal=intTotal + Integer.parseInt(txtDisplay.getText());     }      I get a whole bunch of errors like below:  Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException   I thought maybe what I was doing to convert the text into integer was wrong, but even if I replace with something like:  intTotal=intTotal + 1;   It gives me the same error so I'm not sure what I am doing wrong.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Good day i have another question. I'm making a good progress in rigging. thanks too the this community but i encountered a problem  When i move the character the collar doesn't follow. The character is downloaded here  And sorry for asking too many question. i learn from doing things than watching all the stuff. if i watch a whole series of tutorial i got distracted and lost interest. And this is the blender file  This question is different

I didn't address this in a while because I was busy with something else, but now it has cycled back into my schedule.  Right now I have a shirt modeled and bones set in place. It's already technically rigged, but the only issue is the buttons.   I'm not entirely sure how to go about connecting them to the shirt's deformations. I tried to combine them and the shirt into one object, but because of the shirt's modifiers, (Solidify and subsurf, which I don't want to apply yet), the buttons become extremely deformed. I've tried to match the weight painting intensity where a button is at in correspondence with the shirt, but that doesn't seem to work, maybe it has to do with the specifics of where the button is?   Is there a way to make the buttons follow the shirt's deformations without deforming the mesh vertices of the button? I know that if I probably apply the modifiers on the shirt and combine it with the buttons, it would be okay, but I'm not okay with doing that just yet with the shirt.    I rigged the shirt by deleting all vertex groups, assigning empty groups to the mesh from the armature, and then assigned automatic groups in the weight paint menu.  Is there a way to do this?


I am familiar with programming, but I am learning Java. Why is it ok in Java to say   A test = new B()   Where A would be a different class from B (obviously). I understand that the new B() portion is just calling the initializer method for the B class. What confuses me is why would you WANT to do that? Is the A test creating the object in computers memory, with the initialization of A?    This question has nothing to do with interfaces. Why this is marked as a duplicate I have no idea...

I have seen this mentioned a few times and I am not clear on what it means. When and why would you do this?   I know what interfaces do, but the fact I am not clear on this makes me think I am missing out on using them correctly.   Is it just so if you were to do:  IInterface classRef = new ObjectWhatever()   You could use any class that implements IInterface? When would you need to do that? The only thing I can think of is if you have a method and you are unsure of what object will be passed except for it implementing IInterface. I cannot think how often you would need to do that.   Also, how could you write a method that takes in an object that implements an interface? Is that possible?


I need to improve an existing solution to be able to do multiuser editing within a PostGIS database from ArcMap. Available for the solution is ArcGIS for Desktop 10.3 [Basic]. (No non-free Extensions or ArcGIS for Server)  There is already an existing solution implemented as an ArcMap-AddIn. It uses an editable exchange Format (Shapefile) which is read out to the database and updated from the database if there is a change in the Shapefile or PostGIS database. This solution is prone to errors and needs to be improved.  I know it is possible to read from PostGIS databases in the new ArcGIS for Desktop versions using a query layer. But then the layer can't be edited. The solution needs to be implemented as an Add-In or an Extension. Whatever is required.  As the “” is capable of such a connection. That's why I thought it might be possible to write a ArcMap Extension. Any Advice?  I know similar questions have been asked. But the questions and the answers I found, did relate to old versions of ArcGIS. There has been a lot of change relating PostGIS databases in the resent ArcGIS versions.     I found a clue to a good solution in  answer to a different question. It links to a coustom implementation of a "Plug-in Data Source" (). It is a good example I could use as a template for my PostGIS implementation. But this solution didn't implement write support. The same answer claims, write support for "Plug-in Data Sources" was introdused with version 10.1 SP1. My search didn't find any documentation for this. I can only find the old "read-only"  for "Plug-in Data Sources". In the lower part of the comments to the answer, Ragi Yaser Burhum and Petr Krebs try to implement write support. Sadly they didn't resolve there issues (at least publicly). I think  is a branch of their work. Maybe anybody of you could point me to documentation (or a solution) for write support in a "Plug-in Data Source".

I have been working with QGIS/PostGIS for a while now, without problems, but now I have to change QGIS for ArcGIS Desktop 10.1.  I am having trouble adding a layer from PostgreSQL and being able to edit that layer. I want to work directly with the database, and if I change something in the map it should be reflected on the database.  Can I do this without a Geodatabase?


Blender newbie here, I made a car in blender 2.75 and used the mirror modifier to create its other side. I created a tire that is basically the part of the car mesh, is it possible to separate the tires from the car body so I can use it in my Unity game.   Here's the image

I've just made a set of armor by using a male body mesh model I downloaded and selecting certain faces from the model and duplicating them to create viable armor pieces.   Since the pieces are just duplicated from the same mesh male model, then it's still part of the same object.   How do I separate the armor piece from the model to make the pieces separate?


I have lot of objects which are bounded by opacity mask.   I need to get rid of my opacity mask, clipping each object where it intersects with my mask. It is a lot of hassles to do it manually.  Is there some other easy way? Some automatic clip of all objects?

Is it possible to trim a clipping mask in Illustrator? I have an image that I created a mask for, but the entire image is so much larger than the space I need, I would like to crop the rest of the image to the mask.  Basically, I need the same result as in Photoshop when you Right-click > Apply Mask.


This question is problem 11(a) in chapter 1 in 'Topics in Algebra' by I.N. Herstein.   These are the properties of equivalence relation given in this book.   Prop 1 $a \sim a$ Prop 2 $a \sim b$ implies $b \sim a$. Prop 3 $(a \sim b$ and $b \sim c)$ imply $a \sim c$.   Statement Property 2 of an equivalence relation states that if $a \sim b$ then $b \sim a$. By property 3, we have the transitivity i.e. $a \sim b$, and $b \sim c$ then $a \sim c$. What is wrong with following proof that property 2 and 3 imply property 1? Let $a \sim b$; then $b \sim a$, whence by property 3 (using $a = c$), $a \sim a$.    I think I can prove this to be wrong. Without proving equivalence relation first, one can not use $a = c$. Right? After all, equality is equivalent to 'equivalence relation' and 'axiom of substitution' are satisfied. If this is right, then I have trouble with the next part of this problem.    Part 2 Can you suggest an alternative of property 1 which will insure us that prop 2 and prop 3 do imply 1?  Can one give such a formulation without using the idea of '=' or otherwise?    EDIT : Italics are my comments. Rest is as it appeared in the book.  Notion of Equality  I have read in Terry 'Analysis 1' in Appendix A.7 published by Hindustan Book Agency that there are four axioms of 'equality'. First 3 are same as equivalence relation where $\sim $ in replaced by $ = $. The fourth one is known as axiom of substitution. Given any two objects $x$ and $y$ of some type, if $ x = y $, then $f(x) = f(y) $ for all functions or operations $f$.

Definition: Given a set $X$, a relation $R$ on $X$ is any subset of $X\times X$.  A relation $R$ on $X$ is said to be  reflexive if $(x,x) \in R$ for all $x \in X$, irreflexive if $(x,x) \not\in R$ for all $x \in X$, transitive if $(x,y) \in R$ and $(y,z) \in R$ implies that $(x,z)\in R$, intransitive (or antitransitive) if $(x,y) \in R$ and $(y,z) \in R$ implies that $(x,z)\not\in R$, symmetric if $(x,y) \in R$ implies that $(y,x) \in R$, antisymmetric if $(x,y) \in R$ and $(y,x) \in R$ implies that $x=y$.   Given any combination of the properties listed above, is there a nontrivial (i.e. nonempty) relation which satisfies that combination of properties?


I want to make 1 job and 1 schedule using quartz, but every job is run based table in the database  foreach (var i in query) {  scheduler.ScheduleJob(JobBuilder.Create<i.classname>().Build(), TriggerBuilder.Create()                     .WithSimpleSchedule(x => x                         .WithIntervalInSeconds(40)                         .RepeatForever()                       )                     .Build()); }   i.classname is a string, how to make a class ?

Is there a way to create an instance of a class based on the fact I know the name of the class at runtime. Basically I would have the name of the class in a string.


I've solved an exercise in  that said:     Show that if Lie algebra $L$ is nilpotent, then its Killing form is zero.   I'm wondering is the opposite true? In Humphreys, we work mainly with Lie algebras over an algebraically closed field of characteristic zero, so let's assume that.  This is what I've tried:  Let's assume that Killing form is zero. That gives us solvability of $L$, so we know (as a corollary of Lie's theorem) that there is a basis of $L$ in which all matrices in $ad \ L$ are upper triangular. Then, $\kappa(x,y) = tr(ad(x) \ ad(y))$ is a scalar product of diagonals of $ad(x)$ and $ad(y)$ in that basis. If I could show that this somehow implies that for every $x \in L$ diagonal of $ad(x)$ is all zeros, it would follow all eigenvalues of $ad(x)$ are zero and this would imply that $ad(x)$ is nilpotent. Then,  would give us nilpotency.  But I don't know how to do that.

When is the Killing form $\kappa$ of a Lie algebra $\mathfrak g$ null, i.e. $\kappa(\cdot,\cdot)=0$? Surely this is true for any Lie algebra with trivial bracket, but is this the only case? I can't seem to find any nontrivial examples.


Find the value $C$ such that $\int^{\infty}_{0}(\frac{x}{x^2+1} - \frac{C}{3x+1})dx$ converges  $$\int^{\infty}_{0}(\frac{x}{x^2+1} - \frac{C}{3x+1})dx$$  How do I do this?  The only thing I can think of is creating a common denominator?  $$\displaystyle\int\limits^{\infty}_{0} \dfrac{x^2\left(3-c\right)+x-c}{\left(x^2+1\right)\left(3x+1\right)}\,\mathrm{d}x$$  Something tells me $C = 3$ is right, but I don't know why I think that or if it's even right.

Find the value of the constant C for which the following integral $$\int_{0}^{\infty} \bigg(\frac{x}{x^2+1} - \frac{C}{3x+1}\bigg)dx$$  converges. Evaluate the integral for that value of C. Make sure to fully justify your answer.  \  My solution:   $$\lim_{A\to\infty}\int_{0}^{A} \frac{x}{x^2+1} dx - \lim_{A\to\infty} \int_{0}^{A} \frac{C}{3x+1} dx$$  $$= \lim_{A\to\infty} \frac{1}{2} ln(x^2+1) \bigg|_{0}^{A} - \lim_{A\to\infty} \frac{C}{3} ln|3x+1| \bigg|_{0}^{A}$$  $$= \frac{1}{2}(\infty + 0) - \frac{C}{3} (\infty + 0)$$  Idk how to make it converge.


i've given them a texture but when i render it it looks lame, and kind of scratchy any help?

I know that this question is a bit old or maybe overdone, but I'm running the latest edition of Blender and when I use the Cycles engine I get really fuzzy results and I can't find a simple, non-compromising solution to the quality.  I don't know exactly what I'm doing wrong here, but I'm sure others share my frustration.  Leaving everything in default settings, I started a new project and switched to the Cycles render.  I duplicated the cube and set colors for two Diffuse BSDF shaders, then went ahead and made walls and a floor all sharing the same diffuse shader.  I made two windows to emit blue light.  The screenshot has gaps between the walls because of the setup:  I'm aware that it's considered very incomplete and many have come to terms with some amount of noise, but is this normal?  Furthermore, with default settings or not, I can't change the amount of noise produced.  Supposedly, using "progressively refine" in the rendering tab should make it refine itself indefinitely, however Cycles only counts to 10 refines and then stops, creating a render which is a pixel-perfect match of the ordinary rendering method when it's completed.  I understand that there are tricks that can be used to reduce noise, but at the cost of extra processing time and usually small quality conflicts, like blurring.  My question essentially boils down to is this Cycles' current limit?


Evaluate: $$2\cdot\int_{0}^{1} \frac{\log(x)}{\sqrt{1 - x^2}} dx$$  Using Complex Integration.  I want to do something with the unit circle, but I am not quite sure how to work-around with the unit circle and the integral.  Will someone have an idea?  Thanks =)

I know the integral is possible with a simple fourier series expansion of $-\log(\sin(x))$  But I am interested in complex analysis, so I want to try this.  $$I = \int_{0}^{\pi} \log(\sin(x)) dx$$  The substitution $x = \arcsin(t)$ first comes to mind.   But that substitution isnt valid as,   The upper and lower bounds would both be $0$ because $\sin(\pi) = \sin(0) = 0$  What is a workaround using inverse trig or some other way?  Inverse sine is good, because that gives us a denominator from which we will be able to find poles.  $$x = arctan(t)$$  Is also good, but it would hard to do.  Idea?


I couldn't enable Wifi in my Hp Envy laptop with Ubuntu 14.04. This version is newly installed.   I did try out most of the solutions listed here and they didn't work for me.  This is my output of rfkill list   0: hci0: Bluetooth  Soft blocked: no Hard blocked: no   1: acer-wireless: Wireless LAN  Soft blocked: yes Hard blocked: no   2: phy0: Wireless LAN  Soft blocked: no Hard blocked: no

Note - I know nothing about Linux, just switched over from Windows. Also not an accomplished coder.  Installed Ubuntu 16.04 on a Dell laptop; it worked.  Installed it on an HP laptop (model 17 -x061nr) and the wi-fi will not work. In Network Settings, the option to turn Wireless on is present, but when I click it on it immediately switches back off again. I have no Ethernet ports available. I can download something on the Dell laptop and transfer it via flash drive, but that's it.  The HP's network controller is a RTL8723BE PCIe wireless network adapter, from Realtek. Prior to installing Ubuntu on this laptop, it was running Windows 10; the wi-fi worked there. The wireless isn't entirely kaput - the first time I switched it 'on,' the name of my wi-fi network appeared for half a second before the wireless switched off.  I've powercycled the laptop, reinstalled Ubuntu, and disabled, then re-enabled Networking. I looked in Software & Updates; it had one notification that the device is using an alternative driver (Processor microcode firmware for Intel CPUs from intel-microcode (open source)). I've tried enabling the wireless with and without using that device.  I've looked around the forums for similar issues, but haven't found anything quite like this.  Advice? Any further info required?  rfkill list all: 0: hci0: Bluetooth     Soft blocked: no     Hard blocked: no 1: phy0: Wireless LAN     Soft blocked: no     Hard blocked: no 2: acer-wireless: Wireless LAN     Soft blocked: yes     Hard blocked: no   Update: Wi-fi is now enabled. Thanks very much for the help!