My family and I are travelling from Australia in about a month.  We would like to hire a car from Dublin airport, drive north to Belfast, take it over to Scotland ( via ferry - no other way) and then back to Dublin airport over a period of a month.    Are there any car hire companies that will allow us to take the car from Ireland to the UK? (My research suggests not). Are there any additional steps that I have to take beyond normal renting of a car?

My wife, two kids and I will be traveling in Ireland and the UK Nov. 1st through 21st. We're flying into and out of Dublin. Our plan is to do a clockwise tour: Fly into Dublin -> Belfast -> Scotland -> England/London -> Back to Dublin to fly home.  We've been planning to rent a car when we land in Dublin (doing just things outside Dublin at the start of the trip) and have a car all the way until London, then turn in the car and take a train/ferry to get back to Dublin before flying home.  However, reading through the car rental section of Rick Steve's 2012 Ireland book is causing us to question if this is the right plan.  He says (p. 480):     If your trip covers both Ireland and Great Britain, you're better off   with two separate car rentals, rather than paying for your car to ride   the ferry between the two islands. On an all-Ireland trip, you can   drive your rental car from the Republic of Ireland into Northern   Ireland, but be aware of drop-off charges ($75-150) if you return it   in the North.   So it seems like he recommends against doing one car rental for both islands, but he also recommends against renting in the Republic of Ireland and returning it in Northern Ireland (our other option for our current itinerary).  So we're not sure which is best here.  A few questions about this:   If we do one car rental all the way from Dublin to London, will there be a similar $75-$150 fee? Is there an easy place to return a car on the Northern Ireland side of one of the Northern Ireland -> Scotland ferries, and an easy place on the Scotland side to rent a car?  We'd like to minimize the number of buses/whatever we need to take between car rentals since we'll be lugging around car seats for both of our children (on top of carrying them and our luggage). Will one way be significantly cheaper than the other?  Besides the basic cost of taking the car on the ferry and the drop-off charges, our credit card will cover insurance in Scotland/England but not in Ireland, so we could potentially get a better rental rate by renting a second vehicle once we're on Great Britain. Although, I know you often get a better rate when keeping a car rental for longer, so that may negate any benefit from the credit card covering the insurance.


I got a single entry Schengen visa C type from my Qatar to Italy for 10 days validity on next November and now I have to visit France after those 10 days directly, so is it normal to apply for another visa to France and have back to back two visas one from 02-11 till 11-11 and another one from 11-11 to 17-11?  Also is there any effect of having both as a single entry?

I am traveling to Germany on May 1st for an exhibition for which I have already obtained a visa and its validity is up to May 13th. I am returning on May 12th and then traveling on May 17th to UK, and from UK to Switzerland for vacation with family. As time is very short for applying for a Schengen visa again after returning on the 12th with May 13-14 being a Saturday and Sunday, can I apply for Schengen visa again and can I get 2 valid Schengen visa?


I have  that was asked on a low traffic window (you can see it in the views) and was not answered yet. This is my first experience with a question not being answered almost immediately.  I was wondering if there was a way to draw attention to it without expending rep in a bounty (because it's not that it wasn't answered to my sattisfaction, it wasn't really answered) and without editing it to bump it to the front page (a practice I don't like)

I asked a question almost as soon as I got my account. I got a few decent answers, but none of them helped solve my problem. The question has long since become buried by newer questions, and there's still no accepted answer. Unfortunately, because there are quite a few answers with votes, to a casual observer it probably looks like the question was answered and I just neglected to mark an answer as accepted, and the system does not consider it "unanswered".  Or, I asked a question that was a bit more difficult to answer. After waiting for some time, I received no answers, little or no comments, and only a few views. The question does show up in the "unanswered" list, but no one has answered my question.  In either case, what's the protocol for me to try to get this question answered?  I see several options:   Post the question a second time, possibly linking to the original, to get attention for the original question. This is encouraged on sites like Reddit.  However, it's probably not appropriate here, since we're encouraged to check for duplicates and not submit a question that's already been asked by someone else, so this probably falls under that heading. Wait for some kind of wiki-like talk page to be implemented, then post a plea on the talk page for input and hope that activity on the talk page bumps up the question. Edit the question, but do nothing further on the Stack Exchange site. If I edit my post to say that I haven't accepted any of the current answers but am looking for more, then the question might get answered eventually by people browsing through old questions to find something they can answer. Post the question on other sites, but link to my original question on Stack Exchange. People will either answer here, or they'll answer on the other site and I can post the accepted answer here myself.  This might be considered spamming, so it might be better to do this without the link.      For more information, see the "" page in the .


There is a computer that has been sitting in our lab office that nobody has used in +8 years. It's running Ubuntu 14.04. I've been trying to download some useful software to it, but I've run into a lot of issues with python packages and different things not working.. possibly because of how old this version of Ubuntu is, or issues with what is already installed on it, which I had no part in doing. It tried updating a lot of things the first time I logged onto it, and ultimately I had to revert all of the updates because it no longer worked and got stuck in a login loop. At this point, there is nothing worth saving on this computer, and I would really like to just delete everything and install a newer version of Ubuntu to start from scratch with. Whats the best way to do this?

How will Ubuntu automatically allocate the disk partition sizes when we select Erase disk and install Ubuntu during installation?    Can the settings for automatic space allocation be changed?


Im observing the below behavor in a TCP connection between a server application and a client which run on two different red hat machines.  Example 1   Client acks everything until now (ACK with WND = 1424) Server sends 296 bytes to TCP layer and it is sent to the client(PUSH/ACK) Server sends 296 bytes to TCP layer and it is sent to the client(PUSH/ACK) Server sends 296 bytes to TCP layer and it is sent to the client(PUSH/ACK) Server sends/tries to send 239 bytes to TCP layer but: either one of the following two happens   the OS waits ~30ms until ACK from client is received before sending these bytes (this x bytes send will be referred as delayed message below) the tcp send call returns EWOULDBLOUCK or EAGAIN (I think this is not possible because 239+239+239+239 < 1424. Please correct me if I'm wrong    Example 2   Client acks everything until now (ACK with WND=1424) Server sends 239 bytes to TCP layer and it is sent to the client  Server sends/tries to send 239 bytes to TCP layer and one of the two things in the above happens   The problem I want to understand is why the server application or the OS waits until the ACK when window size for the client is big enough? Is this something I can tune in the OS level. Can I force server to send all bytes until the window of the client is filled?  As per my understanding there are two possible reasons   Server application does not pass the 'delayed message' to TCP level becuase the send system call returned EWOULDBLOUCK or EAGAIN.  Application does pass the message to TCP layer, but the operating system does not send it until an ACK from the client is received.   In all the delayed message scenarios, there is an ACK from the client before the SEND of the delayed message. Also the working logic of the application suggests that it does pass the message to the TCP layer.  Can you please suggest where I should focus on the troubleshooting of this.    Is it some OS level setting I can set in either the client or server side Is this somehow a fault in the application server? Am I wrong in assuming OS doesn't return EWOULDBLOCK until messages fill up the window

The considered application (server) has a number of clients connected. It processes each message from the client and sends two output messages. The output messages are generated sequencially and written to the socket. I observe that occassionnaly the second output message is delayed by a big time for a client. I'm trying to understand the reason for this.   Below is the filtered TCP flow between the application and the client captured from the client side.     14908 is the input message from client. 14910 and 15337 are the two ouput messages 14910 is not delayed. But 15337 is delayed around 40ms. As I can see, the 15337 packet is not sent until the ack 15336 is received.   The application sends a packet to TCP layer if the socket does not return EWOULDBLOCK or EAGAIN . I'm assuming the socket is not blocked because the window published in #14908 is 1424 and #15336(len=229) shouldn't send it to EWOULDBLOCK.  So can you please help me understand what causes the TCP layer from delaying the sending of #15337 until the ack for #15336?


It seems that there has been a regression in the "close" text in the Low Quality Posts review queue. For example, on , it can be seen that  is shown to have cast a "vote to close". As far as I am aware, a question cannot be closed by only sub-3k users from the Low Quality Posts queue, unlike how "Recommend Deletion" works. Is the display of "Close" instead of "Recommend Closure" not incorrect?

I was in the Low Quality Review queue, and the following review confused me:    It's showing eight "Close votes", which should be more than enough to close a question.  I checked the question's , and it wasn't somehow closed, then re-opened in the middle of the review.  So I then checked on each of the users, and noticed that the majority of them are under 3000 reputation, meaning they can only "Recommend Close".    However, all reviews are simply showing as "Close", which is extremely confusing.  Is this a bug, or possibly an undocumented change related to ?    Another recent example:


I have a building dataset that shows areas of different building types ie. educational, medical, and residential.   How do I assign each type of building a numerical value so if I have 7 buildings that are medical type then it would show a value of 1 so I would have 7 rows of "1" in ArcMap?

I'm looking for duplicate records in dbf files based upon the attribute called 'ID'. I have various dbf files from 500,000 records to 1.5 million and I know there are a host of duplicates.   I would like to add a field 'Duplicate' that says Yes or No (or 1 or 0 is fine) when the ID attribute is present elsewhere. Using the following python script in Field Calculator returns 1 for a duplicate entry and 0 for unique entry;  uniqueList = [] def isDuplicate(inValue):   if inValue in uniqueList:     return 1   else:     uniqueList.append(inValue)     return 0 isDuplicate(!FIELD_NAME!)   However, the 1st record of, for example, 5 duplicate IDs will also be returned as a 0 (the subsequent 4 are considered the duplicates). I would need all 5 to be marked as duplicate as the ID exists elsewhere.  Using the following code will give you an incremental count of how many times that ID occurs with 1 meaning the 1st occasion and so forth;  UniqueDict = {} def isDuplicateIndex(inValue):     UniqueDict.setdefault(inValue,0)     UniqueDict[inValue] += 1     return UniqueDict[inValue]  isDuplicateIndex( !YOUR_FIELD! )   I just want a 1 (or Yes) if the ID of that record exists elsewhere! (ArcGIS version 10.1)  I have seen other answers such as  but it doesn't quite work.


I want to compute the last four digits of $7^{2020}$ using the Chinese Remainder Theorem (CRT). Here is what I've got so far: Obviously \begin{align} 10000 = 10^4 = 2^4 \cdot 5^4, \end{align} so due to CRT we know \begin{align} \mathbb{Z}/10000\mathbb{Z} \cong \mathbb{Z}/16\mathbb{Z} \times \mathbb{Z}/625\mathbb{Z}. \end{align} I also do know that \begin{align} \varphi(16) = 8 \quad \text{and} \quad \varphi(625) = 500 \end{align} and therefore \begin{align} 7^8 \equiv 1 \operatorname{mod} 16 \quad \text{and} \quad 7^{500} \equiv 1 \operatorname{mod} 625. \end{align} (I know that one can find a lot of almost similar questions here on MSE, but I am only interested in solutions, which use CRT. That's due to the fact that I struggle to see how CRT works for those kind of problems. Up to now I used CRT only to compute a solution for multiple congruences. Hence, I would appreciate solutions/hints which straight forward show how to apply CRT here (without any fancy tricks etc.).)

How do I get the solution given by CRT to match another solution, e.g. the least positive? For example say I have X = 1234. I choose mi as 5, 7, 11, 13. This satisfies the simple requirements of . More precisely given in my example k = n = 4, and the product of any k - 1 is smaller then X how come simply computing the remainder of each won't give equations that solve to X = 1234. In the case of the example, x = 4 mod 5 x = 2 mod 7 x = 2 mod 11 x = 12 mod 13  Which resolves to  (won't CRT produce the smallest?) Any hints?  Below is the solution linked to on "Math Celebrity" (cached to avoid link rot).


I thought this would work nmcli d wifi list wlo1 ssid ZTE_H168NA66FE3 password *********** I got this Unknown parameter: wlo1 Unknown parameter: ssid Unknown parameter: ZTE_H168NA66FE3 Unknown parameter: password Unknown parameter: AZsyPnsU IN-USE  SSID               MODE   CHAN  RATE        SIGNAL  BARS  SECURITY          *       ZTE_H168N87DF8C    Infra  10    270 Mbit/s  93      ▂▄▆█  --    My interface  cat /proc/net/wireless Inter-| sta-|   Quality        |   Discarded packets               | Missed | WE  face | tus | link level noise |  nwid  crypt   frag  retry   misc | beacon | 22   wlo1: 0000   70.  -31.  -256        0      0      0      2      2        0  How to fix this problem?

i need to learn to do it just using the commands in the terminal. any help would really help thanks


Mostly the reason given is that that three numbers are required to specify a point uniquely in our world. But this is utter nonsense!  It has long been mathematically proven that $\mathbb{R}$ is in bijection with $\mathbb{R}^3$, i.e. $\mathbb{R}$ and $\mathbb{R}^3$ have the same . So what is the “additional theoretical structure” (which has to be physical, not mathematical, since we’re describing our physical world) that prompts us to label our space as “3D”?    Note: I am not talking about including time as the fourth dimension. This is under the theory of relativity. And I am asking a more general question.

I've often heard the argument that having 3 spatial dimensions is very special. Such arguments are invariably based on certain assumptions that do not appear to be justifiable at all, at least to me. There is a  on Wikipedia.  For example, a common argument for why >3 dimensions is too many is that the gravitational law cannot result in stable orbital motion. A common argument for <3 dimensions being too few is that one cannot have a gastrointestinal tract, or more generally, a hole that doesn't split an organism into two.  Am I being overly skeptical in thinking that while the force of gravity may not be able to hold objects in stable orbits, there most certainly exist sets of physical laws in higher dimensions which result in formation of stable structures at all scales? It may be utterly different to our universe, but who said a 4D universe must be the same as ours with one extra dimension?  Similarly, isn't it very easy to conceive of a 2D universe in which organisms can feed despite not having any holes, or not falling apart despite having them? For example, being held together by attractive forces, or allowing certain fundamental objects of a universe to interpenetrate, and thus enter a region of the body in which they become utilized. Or, conceive of a universe so incomprehensibly different to ours that feeding is unnecessary, and self-aware structures form through completely different processes.  While I realise that this is sort of a metaphysical question, is 3+1 dimensions really widely acknowledged to be particularly privileged by respected physicists?


$$\sum_2^\infty e^{3-2n}$$  I only have memorized the sum of at index zero. So I reindex  $$\sum_0^\infty e^{-2n-1}$$  This gives me the sum as  $$\frac{1}{1- \frac{1}{e} }$$  This is wrong. Why?

$$\sum_2^\infty e^{3-2n}$$  The formulas for these things are so ambiguous I really have no clue on how to use them.  $$\frac {cr^M}{1-r}$$  $$\frac {1e^2}{1-\frac{1}{e}}$$  Is that a wrong application of the formula and why?


if I use:  \includegraphics{Graph}   the image will show up, but not if I use  \begin{figure} \includegraphics{Graph} \end{figure}   Any idea why? Missing package? I need it because in the figure I will add the caption and label...  Thanks  Minimal example:  \documentclass[twoside]{article} \usepackage[utf8]{inputenc} % Use 8-bit encoding that has 256 glyphs \usepackage[hmarginratio=1:1,top=32mm,columnsep=20pt]{geometry} % Document margins \usepackage{multicol} % Used for the two-column layout of the document \usepackage{graphicx} \begin{document} \begin{multicols}{2} % Two-column layout throughout the main article text  I add the figure. \begin{figure}  \includegraphics{Graph} \end{figure} % \includegraphics{Graph} % with this would work \end{multicols} \end{document}   Solution:  Don't use begin and and figure.  Use direct \includegraphics{Graph} and on a new line \captionof{figure}{the caption}\label{textorefer}  Thanks all for the help!!

I want to add an image to my paper but I have a problem.  When I add the image with just \includegraphics[]{} tag, everything works fine, and the picture shows up when I compile my document.  When I use \begin{figure} \includegraphics[]{} \end{figure} - syntax the image does not appear in the compiled document.   The relevant part of my header include is :   \usepackage{graphicx}  \graphicspath{ {pics/} }   And later on I add the image with this block:  %This does not work  \begin{figure}   \centering     \includegraphics[width=.4\textwidth]{generalPolya}   \label{generalPolya} \end{figure}    %This works  \includegraphics[width=.4\textwidth]{generalPolya}   I guess it's some sort of issue in the graphics package, but I've copied the setup from a previous paper I had, so it should work. Any ideas on what's wrong? Thanks in advance.  Edit:  Thanks for all the responses. I created a minimal working example. Apparently multicols messes with the figure tag:  \documentclass[]{article} \usepackage{multicol} % Used for the two-column layout of the document \usepackage{amsmath} \usepackage{graphicx} \graphicspath{ {pics/} } \title{\vspace{-15mm}\fontsize{24pt}{10pt}\selectfont\textbf{Lorem ipsum}} % Article title \begin{document} \maketitle % Insert title \begin{multicols}{2} % %This does not show up \begin{figure}[h]     \includegraphics[width=.4\textwidth]{generalPolya} \end{figure} %This shows up. \begin{center}         \includegraphics[width=.5\textwidth]{chair} \end{center} \end{multicols} \end{document}   What shows up after compiling the document is this    What is wrong with this syntax?


I have a multiple-entry Italian Schengen visa that will last a couple of months. Within this period, I want to go to Switzerland for a weekend, and to Austria for another weekend. Can I just get on a train and arrive there? Or do I need to do some paperwork, request another visa, or something?

I am going to apply for visa to go Germany, but I have an idea to go Belgium too. Is it possible to enter Belgium if I have visa for Germany.


Are there any more "proofs" of an accelerated expansion of the universe other than: $1:$ that galaxies that are farther away from us are also more redshifted. $2:$ using "Baryon acoustic oscillations" to compare the sound horizon today with the sound horizon at the time of decoupling (using the CMB)?

Astrophysicists believe that dark energy exists and makes up ~70% of the universe's energy content. What is the evidence that dark energy exists? Wikipedia gives :   Supernovae. A specific type of supernovae (type 1A) are supposed to be standard candles - that is, their luminosity is known. In turn this lets us measure distance to faraway galaxies, check how fast those galaxies are receding from us, and check if that recession speed is increasing over time. CMB. Data from the Cosmic Microwave Background indicates the universe is approximately flat. Visible matter + dark matter can account for ~30% of the energy content required to make the universe flat, leaving ~70% for something else - dark energy. BAO. Baryon acoustic oscillations act as a "standard ruler" that lets us measure how the Hubble constant varies with redshift (i.e. time), and see if the recession speed is increasing with time. Late-time ISW. ISW stands for integrated Sachs-Wolfe effect. The idea is that, usually, a photon that enters a potential well gains energy as it falls in and loses energy as it emerges, and gain/loss exactly cancel. If a universe is expanding in accelerated fashion, then this is untrue; the potential wells / hills are smoothed out and there is a permanent shift in the photon's energy and therefore temperature. If we see a correlation between hot and cold spots on the CMB and the locations of superclusters and voids, then it's a sign of accelerated expansion. Galaxy evolution. This uses (known) evolution of early-type galaxies as a standard clock. Once we know how long it takes for a galaxy to evolve from one state to another, as well as their redshifts, we can reconstruct how the Hubble constant varies over time, and see if the recession speed is increasing with time.   Two questions:   Did I understand any of these five methods wrong? Are there any other lines of evidence for the existence of dark energy?


I had some problems with Apache, so I removed the entire folder from /etc , /var... now the command:  sudo apt-get install apache2   doesn’t work, I guess because there are no apache folder anymore. So:   Do I have to download it? Any other solution?

I recently was messing around with my Apache config and wanted to reinstall so I could start from fresh. I followed some forum posts about reinstalling the apache2 package and this ended up deleting my /etc/apache2 folder.  Now matter how many things I try I can't seem to do a full wipe of the Apache install and then reinstall. sudo apt-get install apache2 or reinstall doesn't do anything. I can't seem to remove it using Synaptic either.   Is there anything I can do to have a fresh Apache install on my computer again?


I understood the "technique" for doing SVD and PCA.  However, I couldn't understand these two claims:   PCA/SVD decorrelate the variables They do so using orthogonal transformations   For 1, PCA does the eigen decomposition of covariance matrix and SVD operates on the data matrix. How to explain that they decorrelate the variables?  In 2, I think I am missing some matrix transformation properties. How to see the transformations involved in the techniques of PCA/SVD and why are they only orthogonal.  Many thanks.

Principal component analysis (PCA) is usually explained via an eigen-decomposition of the covariance matrix. However, it can also be performed via singular value decomposition (SVD) of the data matrix $\mathbf X$. How does it work? What is the connection between these two approaches? What is the relationship between SVD and PCA?  Or in other words, how to use SVD of the data matrix to perform dimensionality reduction?


I have tried running both Firefox and Chromium. Both state I need to run Microsoft Silverlight to watch. Can't put Silverlight in Ubuntu. Does anyone have any links I can check to get more detailed instruction? Thanks.

I just installed 14.04 LTS on my laptop. I tried to go on Netflix but it tells me to install silverlight but that does not work either. What are my options to get Netflix working on my laptop?


I've just upgraded to Valmiera in QGIS, the only way to do spatial analyses appears to be with the experimental AniMove plugin (?) which is not appearing in my GUI.   Can anyone tell me where to find the plugin and how to make it work?

I have sucessfully installed AniMove by activating experimental plugins (yay! thanks gis.stackexchange). But I can't find it in Qgis! Yes I have activated it. Where is it? Is this a common bug? I searched for it the toolbox, I looked up the names of the several single tools based on this  and only found "Kernel Density", which is filed under SAGA. But I don't have SAGA installed (and don't know if I need to?)


I'm using a blue wire as a c-wire, however when I went to connect the blue wire at the furnace, it already had a white wire ( not from a thermostat) corrected to the c-terminal. Can / wires be connected to c terminal? If not, what do I do with the white wire?  Thanks

TL;DR: Can you terminate more than one common on the furnace C terminal?   Background:  I've linked a diagram of how my non-programmable thermostat is currently hooked up. I want to replace it with a Trane Z-Wave thermostat that requires constant power. There's already a blue wire in the 18/5 bundle, but it's disconnected on both ends. The C terminal on the furnace control board is already in use by the rooftop condenser. If possible, I'd like to connect the blue wire to the stat and terminate it on the same C terminal on the furnace that is already in use by the A/C.    Some model numbers:   Furnace: Goodman GKS9 Gas Furnace with A/C (CAPF) -  Old stat: Honeywell TH3210D1004 non-programmable New stat: Trane TZEMT400BB3 Z-Wave


I have a method to search an specific item, but when i use this code and try to use the return object, i get NullPointerException  public Obra buscarInfoObra(String filtro) {     SQLiteDatabase db = helper.getReadableDatabase();     Obra obraSelecionada = null;       Cursor cursor = db.rawQuery("SELECT * FROM " +BancoDadosHelper.TABELA_OBRA+ " WHERE "+BancoDadosHelper.COLUNA_NUM_OBRA + "=" +filtro, null);      if (cursor.moveToFirst()){         String numObra = cursor.getString(cursor.getColumnIndex(BancoDadosHelper.COLUNA_NUM_OBRA));         int anoObra = cursor.getInt(cursor.getColumnIndex(BancoDadosHelper.COLUNA_ANO_OBRA));         String descObra = cursor.getString(cursor.getColumnIndex(BancoDadosHelper.COLUNA_DESCRICAO_OBRA));         String jurisdicionado = cursor.getString(cursor.getColumnIndex(BancoDadosHelper.COLUNA_JURISDICIONADO));         String tipoObra = cursor.getString(cursor.getColumnIndex(BancoDadosHelper.COLUNA_TIPO_OBRA));         String tipoObjeto = cursor.getString(cursor.getColumnIndex(BancoDadosHelper.COLUNA_TIPO_OBJETO));         String endereco = cursor.getString(cursor.getColumnIndex(BancoDadosHelper.COLUNA_ENDERECO_OBRA));          obraSelecionada = new Obra(numObra,anoObra,descObra,jurisdicionado,tipoObra,tipoObjeto,endereco);     }      cursor.close();     db.close();     return obraSelecionada;   What i'm doing wrong?  [EDIT]This is not a duplicate,i know what is a NullPointerException, but i don't understand why im getting this exception. I already try to put an existing data directly on code, but still getting NullPointer..

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?


What is the simplest/best way to ensure only one instance of a given script is running - assuming it's Bash on Linux?  At the moment I'm doing:  ps -C script.name.sh > /dev/null 2>&1 || ./script.name.sh   but it has several issues:   it puts the check outside of script it doesn't let me run the same script from separate accounts - which I would like sometimes. -C checks only first 14 characters of process name   Of course, I can write my own pidfile handling, but I sense that there should be a simple way to do it.

What's a quick-and-dirty way to make sure that only one instance of a shell script is running at a given time?


I'm trying to hide/show metaboxes dependant on the page template chosen. This has been working fine until I have come to show a metabox on more than one chosen page template.  The below code displays the Rich Content Editor for default pages, but not page-child.php pages. I'm guessing I have written the code incorrectly:  (function($){     $(function() {         $('#page_template').change(function() {             $('#postdivrich').toggle($(this).val() == 'page-child.php') ;             $('#postdivrich').toggle($(this).val() == 'default') ;         }).change() ;     }) ; })(jQuery) ;

I'd like to have a custom field interface show up only when a certain template is assigned to a particular WordPress page.  Any ideas?


Let's say you measure the time it takes for 10 oscillations of a mass undergoing simple harmonic motion to within ± 0.01s, what is the uncertainty of the period of one oscillation?

I have a number of measurements of the same quantity (in this case, the speed of sound in a material). Each of these measurements has their own uncertainty.  $$ v_{1} \pm \Delta v_{1} $$ $$ v_{2} \pm \Delta v_{2} $$ $$ v_{3} \pm \Delta v_{3} $$ $$ \vdots $$ $$ v_{N} \pm \Delta v_{N} $$  Since they're measurements of the same quantity, all the values of $v$ are roughly equal. I can, of course, calculate the mean:  $$ v = \frac{\sum_{i=1}^N v_{i}}{N}$$  What would the uncertainty in $v$ be? In the limit that all the $\Delta v_i$ are small, then $\Delta v$ should be the standard deviation of the $v_i$. If the $\Delta v_i$ are large, then $\Delta v$ should be something like $\sqrt{\frac{\sum_i \Delta v_i^2}{N}}$, right?  So what is the formula for combining these uncertainties? I don't think it's the one given in  (though I may be wrong) because it doesn't look like it behaves like I'd expect in the above limits (specifically, if the $\Delta v_i$ are zero then that formula gives $\Delta v = 0$, not the standard deviation of the $v_i$).


A programming error lead to multiple insertions of identical rows in this table.  I am aware that constraints in the schema could prevent the insertions.    I am trying to find a way to delete all but the newest (highest id) row for each round/number pair.  I could definitely script this but I wondered if there is a way to do this in pure SQL?

What is the best way to remove duplicate rows from a fairly large SQL Server table (i.e. 300,000+ rows)?  The rows, of course, will not be perfect duplicates because of the existence of the RowID identity field.  MyTable  RowID int not null identity(1,1) primary key, Col1 varchar(20) not null, Col2 varchar(2048) not null, Col3 tinyint not null


This article was very helpful, but would also like to include a previous button, is it possible?

Is there a way of adding a button in the Dispform.aspx or the editform.aspx that will take you to the next item in the list?


I'm getting this error package inputenc error unicode char - (U+2212) on the following part of my text: (it's happening at lines 98-99)  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{amssymb} \usepackage{graphicx} \usepackage[english]{babel}  \title{Discrete math Assignment 4} \author{Me} \date{January 2018} \setlength{\parindent}{0pt}  \begin{document}  \maketitle    \textbf{Exercise 4b)} Let $x \in N$. Let $x_k, x_{k−1}, \cdots , x_1, x_0$  %98        be the digits of $x$, so that %99 $$x = x_k 10^k + n_{k-1} 10^{k-1} + \cdots + x_1 10 + x_0.$$ Note that $10 \equiv -1$ ($\mod{11}$). Thus $$x \equiv x_k(-1)^k + x_{k-1}(-1)^{k-1} + \cdots -x_1 + x_0  (mod\ 11 )$$  $$ = (x_0 + x_2 + x_4 + \cdots ) - (x_1 + x_3 + x_5 + \cdots) ( mod\ 11).$$  We have $11|x$ if and only if $x \equiv 0 ( mod\ 11)$, i.e. if and only if $$x_0 + x_2 + x_4 + \cdots \equiv x_1 + x_3 + x_5 + \cdots\  (mod\ 11). $$ In other words, $11|x$ if and only $11$ divides the difference of the sums of the even and odd place digits of $x$.  \end{document}

My beamer presentation presents this problem Package inputenc Error: Unicode char − (U+2212)(inputenc) not set up for use with LaTeX. \end{frame}. I tried remove some elements and I see that problem appear when I use - in equation. I'd like one hint about this problem.   \documentclass[pt]{beamer} \usepackage[T1]{fontenc} \usepackage{amsmath} \usepackage[utf8]{inputenc} \usepackage[brazil]{babel} \usepackage{upgreek} \usepackage{mathtools} \usetheme{Berlin}  \begin{document} \begin{frame}{Convergência - Prova}     %\justifying     Sem perda de generalidade a demonstração foi focada numa partícula unidimensional. Reescrevendo a Equação, tem-se que     \begin{equation}     x_i(t + 1) + \alpha_1 x_i(t) + \alpha_2 x_i(t − 1) = \alpha_3     \end{equation}     onde     \begin{equation}     \begin{aligned}     \alpha_1 &= (1 + \omega) + u(r_1 - r'_1)c_1 + u(r_2 -r'_2)c_2 + c_1r{'}_1 + c_2r'_2 \\     \alpha_2 &= \omega \\     \alpha_3 &= u(r_1 - r'_1)c_1p + uc_2(r_2g - r'_2n) + c_1r'_1p + c_2r'_2n                         \end{aligned}     \end{equation} \end{frame} \end{document}   Sorry by english


Hi I am forcing nginx to use SSL for port 8080, here is my conf:  server {         listen        8080 ssl;         server_name   example.com;         access_log   /var/log/nginx/access.log  main;          include /etc/nginx/ssl.conf;          location / {             proxy_pass         http://192.168.1.20;         }      }   the https://example.com:8080 works fine but when use http://example.com:8080 the nginx has the error message shown:  The plain HTTP request was sent to HTTPS port   now my question is how to get http://example.com:8080 auto redirect or rewrite to https://example.com:8080 by editing my nginx conf file?

I have one nginx server setup(two config files) with two gunicorn web servers setup and running. One gunicorn is production and the other is staging.   I want nginx to serve http requests to xyz.com as well as https requests to xyz.com to the production gunicorn server @ 127.0.0.1:8000.    I have accomplished this with:  server {    listen 80;    server_name xyz.com;    return 301 https://$http_host$request_uri; }  server {    listen 443 ssl;    server xyz.com;    ..... <<< ssl stuff   location /{       .... proxy_stuff       proxy_pass http://127.0.0.1:8000;   } }   I also want http traffic to xyz.com:8080 and https traffic to xyz.com:8080 to hit the staging server @ 127.0.0.1:8081. I have been been able to get https traffic to xyz.com:8080 working as follows:  server {    listen 8080 ssl;    server_name xyz.com;    ...... << ssl stuff    location / {       ...... << proxy stuff       proxy_pass http://127.0.0.1:8081;    } }   But I can't seem to find a way to redirect http traffic at xyz.com:8080 to https traffic at xyz.com:8080. I have tried the same redirection that I did with port 80 but have not been successful.   Could use some direction.


infinite small or large, infinite slow or fast, infinite long time or short, any kind of infinite counts. Are there any real-life example out of Math, that is infinite? This is the whole knowledge I know now: size: I know Planck length is the observation size limit, so, are there 0 point particles exist? Electrons don't have size, but is it the same to say "don't have size " and "size is 0"? Observable universe have a 45 Billion light year radius, so there is a maximum size limit, right? time: Planck time is the shortest time; the life span of the universe is the longest time. speed: Light speed is the fast limit; 0 kelvin does not exist, so 0 speed does not exist. mass: The energy of our universe is finite so the mass is finite, information is finite too. difference: not only 0 speed does not exist. all rational number are not exist, all number are not constant, in real life. Can you find exactly 3 apples? no matter how did you define what is "a apple" you always get more or less amount of your definition in real world. Did I made mistakes? Are there any examples that are infinite? P.S. I don't know which tag this question belongs to. help me to add them please. P.S. help to Solve the question, not Block the question, please.

Sometimes people fail at asking a question by being too broad, unclear like . So I'll take a stab at what I believe to be the same question, but more concise and clearly stated:     Does infinity exist in either terms of structure, parameters, or   measurement in any physical systems?   Can infinity have any real connection with reality?  Or is infinity purely a mathematical concept just used by physicists as a convenient way to describe the very large, an approximation?  I have heard that if you model a physical system (), and you run into infinity as a solution, then you have either made an error in your calculations or your model is wrong.


I need a verb meaning "to present a fact/the facts".  E.g. "If you cannot lie you must word here".  I know using multiple words is easy but I need it to be one word.  I do not mean "to speak honestly" because that is too vague and unlike this word, it would not fit.  E.g.    If someone asks "How many people watched the 1966 FIFA World Cup Final: England v West Germany?"  If you said "I don't know." you would be speaking honestly but you would not be presenting the "truth/facts" about it.  If you said "32.80 million rounding to the nearest 10,000. You would be presenting the facts"

What is a verb to describe someone speaking honestly? Instead of "Joe speaks honestly about today", I'd like to say "Joe honests about today". But an actual, real word.


I've recently been looking at different questions and proofs in my book and one eludes me for the 2nd day in the row.     Let $N \geq 4$. Show that if $p$ is a prime such that $p \equiv 1 \pmod{N!}$ then none of the numbers $1, 2, \ldots, N$ are primitive roots modulo $p$.   I've tried using CRT, the fact that $\left(\frac{ab}{p}\right) = \left(\frac{a}{p}\right)\left(\frac{b}{p}\right)$ and Gaussian sum $G(p)$ properties, yet to no avail.  This proof has been really bugging me, could you please point me in the right direction?

for $N \ge 4$. Show for prime numbers,  $p \equiv 1$ mod $(N!)$ that none of the numbers $1,2,...,N$ are primitive roots modulo $p$   I can't figure out where to start with this question, all I can think to use is the Legendre symbol and Euler's Criterion but I haven't been able to do it. Any help would be much appreciated.


for $N \in \mathbb N$ and $k \in \mathbb N$ prove that there exist unique $0\le x_1 \lt x_2\lt \dots \lt x_k$ such that $$N = \sum_{i=1}^k \binom{x_i}{i}$$  edit: i've tried looking for combintorial proof but i couldnt find the right interpretation since $x$-es are not given.  then i tried looking at right pascal triangle and tried a few numbers, I found out that i always take the biggest possible $x_k$ for $k$, then the biggest possible $x_{k-1}$ for $k-1$ sort of how you find binary expression for natural numbers.

I need some advice as I am struggling with the following combinatorics exercise.  Let $k$ be a given positive integer. Show that any non-negative integer $N$ can be written uniquely in the form $$N=\binom{x_k}{k}+\binom{x_{k-1}}{k-1}+\dots+\binom{x_1}{1},$$ where $0 \leq x_1 < \dots < x_{k-1} < x_k$.  The exercise is accompanied by this advice:  Let $x$ be such that $\binom{x}{k} \leq N < \binom{x+1}{k}$. Then any possible representation has $x_k = x$. Now use induction and the fact that $N-\binom{x}{k} < \binom{x}{k-1}$ to show the existence and uniqueness of the representation.  I am really stuck and thus grateful for the slightest hint on how to solve it.


How can I show that for positive reals $$ \frac{a}{b}\leq \frac{c}{d}, $$ that $$ \frac{a}{b}\leq\frac{a+c}{b+d}\leq\frac{c}{d}. $$ Thanks in advance.

I'm reading a introductory book on mathematical proofs and I am stuck on a question.     Let $a, b, c, d$ be positive real numbers, prove that if $\frac{a}{b} < \frac{c}{d}$, then $\frac{a}{b} < \frac{a+c}{b+d} <\frac{ c}{d}$.


I was just wondering if it is possible to install Ubuntu on a USB Flash Drive, and then run Ubuntu from the USB without rebooting, touching the boot menu, or installing. Just using it on Windows 7, from a USB. Then, say the USB is removed, it goes back to Windows 7.  Many of you will probably ask why I would do this when I can just install it, and here's why: I already have Ubuntu installed at home, but I want to run it at school without touching anything I could get in trouble for. Also, I have no administrator rights, except I do know how to use the login screen as an admin account, but I can't download anything. (I enabled command prompt in the login screen in place of sticky keys, and then typed: explorer.exe to bring up the start menu, etc,)  Anyway, again, I was just wondering if this is possible to do. Thanks.

If you are hurrying to reply, System → Administration → StartUp Disk Creator -- no, that's not what I'm talking about.   I want to try Ubuntu 11.04's Unity without touching my existing Ubuntu install.  To do this, I need to install the nVidia drivers first (sigh).  To do this, I need changes to persist a reboot.  To do this, I need to really install Ubuntu on a USB key.  How do you do that?    What I tried   I tried to make a USB key from , then boot from it, then choose "Install Ubuntu." The installer refused to install to the installation media itself. I tried, from my installed copy of Ubuntu:  sudo kvm /dev/sdb --cdrom .cache/testdrive/iso/ubuntu_natty-desktop-i386.iso   ...but the installer didn't detect the disk properly.


I'm having a problem with the result of the average in my UserForm. So, I have 4 textboxes where the user will input the grades then upon clicking the button, it will get the average of it. Here's my code: Dim Total As Double, i As Integer    If IsNumeric(tb_music) Then Total = Total + CDbl(tb_music): i = i + 1  If IsNumeric(tb_arts) Then Total = Total + CDbl(tb_arts): i = i + 1  If IsNumeric(tb_pe) Then Total = Total + CDbl(tb_pe): i = i + 1  If IsNumeric(tb_health) Then Total = Total + CDbl(tb_health): i = i + 1    tb_mapeh.value = Round(Total / i, 0)  I tried to input a grade of 88, 91, 92, and 91. When using a calculator, the result will be 90.5, right? The result of my code above is 90. I need to show the result as 91. Can someone help me? Any help is highly appreciated. Thank you!

I had an application for returning closest matches to certain values in a large  cluster of values( as in my earlier )   and I chose a VBA solution. While in the course of using the said application, I observed that the results for the value of 0.5 were not correct. I had been using the VBA Round function which I found to be returning 0 for 0.5 rounded to integer whereas the worksheet round function returns 1. Strangely, the VBA round function returns 2 for 1.5. I had to substitute the worksheet function in place of the VBA one.  Am I missing something?


The question is  and it shows up as follows when I use          Note there is a question that looks similar but is essentially different, as it's a 1 year old, status-completed bug report:

I watch a number of different tags at the same time using the tag filters and I noticed that today, the sort order of the newest tab seems to have an issue.  Towards the bottom of the first page, I have questions from May 2011 and Dec 2011.  There seems to be questions missing/skipped in the sorted list.   When I check the old questions listed, I can see no recent updates that would have pushed it to the top.  Even so, newest sort order used to be ordered by the question posted date, not active date.    See  for example.  Is this bug?  How can I restore the correct sort order as it was before?  EDIT: Just checked again and now it's fixed.  I wonder, what was the problem?


I am trying to insert comments in my component mark up but it is failing to save with the error :  "Failed to save undefined: markup://c:TestComp:6,72: ParseError at [row,col]:[7,72] Message: The string "--" is not permitted within comments.: Source"  This is because of the two dashes that I am using in slds class(like slds-text-heading--medium) for one of the tag that I am enclosing in comments. Is there any work around for this?  For Example :  <!--<div>         <ui:button class="slds-button--brand" label="click me" aura:id="button" press="{!c.clicked}"/>         <ui:button class="slds-button--brand" label="click2 me" aura:id="button2" press="{!c.clicked2}"/>         <button class="slds-button slds-button--brand" press = "{!c.clicked2}">Button</button>  </div>-->   Issue is coming because for buttons I am using slds-button--brand styling and -- is not allowed within commented code.

In a Lightning Component, I have the following markup which I have to comment in and out for testing purpose  <force:inputField value="{!v.account.Name}" class="form-control uiInput--input input" />   now when I try to comment it out like this  <!--<force:inputField value="{!v.account.Name}" class="form-control uiInput--input input" />-->   the API tells me     markup://c:elfL1:6,81: ParseError at [row,col]:[7,81] Message: The   string "--" is not permitted within comments.   Since I didn't figure out that fancy class name uiInput--input (Salesforce did so...) it would be nice to be able to toggle that om/off OR avoid to use class names like this...


Given the matrix $A$ such that $A^3=0$. Determine if matrix $A^2-A+I$ is invertible, and if it is, find it's inverse.  Is it possible to directly evaluate matrix $A$ from the condition $A^3=0$? If not, can we use Cayley-Hamilton theorem?

Is the matrice $A^2-A+I$ invertible?  $A^2=A-I /\cdot A$  $ A^3 = A^2 - A$  $A^2=A$  Thus I conclude that $\lambda=0$ is one of the eigenvalues of this matrice and it isn't invertible, my conclusion comes from the fact that the eigenvalues of the matrices $A,A^2,...$ are all connected, and if $A^3=O$ that means that those two have the same eigenvalues.


So uh, I'm rather new to the Cycles Engine, and while I've been able to find a lot of it out, I'm struggling with one specific thing. The center of this model I'm working on, (Not my model by the way) has a kind of ball of lightning in the center, comprised of multiple plane meshes kind of randomly rotated within the model. However, attempting to recreate this in cycles is giving... odd results.  As you can see, the alpha is getting applied properly, but as multiple of the meshes layer up, the meshes kind of, create a blackness again, as if they were created without the alpha layer. But as you can see, the edges of the lightning, where there isn't another mesh behind it, is still transparent.    You can observe it more here with this tower of planes, after five or so, they suddenly turn black.

Using v2.73, cycles and a very simple scene: an array of cubes, no big deal.   If I set the shader's material to transparent, the cubes in the foreground do become transparent but those far away in the back do not disappear completely and this strange dark things appear (visible in rendered mode and in final renders)    I've played with the clipping distance on the viewport and camera, but I can't figure out how to make those ghosts go away...


I want to create Key/Value Pair but with only one Set, not Dictionary with multiple pairs. (I don't want to use Array of size 2.)  What is the best way to do in C#?

I'm interested: What is C#'s analog of std::pair in C++? I found System.Web.UI.Pair class, but I'd prefer something template-based.  Thank you!


I have come up with 2 approaches but I'm not sure which one would be more appropriate.  1) $E[XY] = \sum_{m = 1}^{\infty} kP(X = k) * \sum_{n = 1}^{\infty} tP(Y=t)$  2) $E[XY] = \int_{-\infty}^{\infty}\int_{-\infty}^{\infty}xyf_{X,Y}(x,y)dxdy$  I am asked to prove the following.  $$E[XY] = \sum_{m=1}^{\infty}\sum_{n=1}^{\infty} P(X \geq m, Y \geq n)$$

Let $X$ be a non-negative random variable and $F_{X}$ the corresponding CDF. Show,   $$E(X) = \int_0^\infty (1-F_X (t)) \, dt$$   when $X$ has : a) a discrete distribution, b) a continuous distribution.   I assumed that for the case of a continuous distribution, since $F_X (t) = \mathbb{P}(X\leq t)$, then $1-F_X (t) = 1- \mathbb{P}(X\leq t) = \mathbb{P}(X>  t)$. Although how useful integrating that is, I really have no idea.


I ran a two-way ANOVA and got a significant interaction. I ran a Tukey.HSD() post-hoc test in R and no pairwise comparisons were significant. Is this an error on my part? My adviser insists that this is not possible. If it is possible, why does this happen?

I performed with R an ANOVA and I got significant differences. However when checking which pairs were significantly different using the Tukey's procedure I did not get any of them. How can this be possible?  Here is the code:  fit5_snow<- lm(Response ~ Stimulus, data=audio_snow) anova(fit5_snow)  > anova(fit5_snow) Analysis of Variance Table  Response: Response           Df Sum Sq Mean Sq F value  Pr(>F)   Stimulus   5  73.79 14.7578  2.6308 0.02929 * Residuals 84 471.20  5.6095                   --- Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1   df<-df.residual(fit5_snow) MSerror<-deviance(fit5_snow)/df  comparison <-  HSD.test(audio_snow$Response, audio_snow$Stimulus, df, MSerror, group=FALSE)  > comparison <-  HSD.test(audio_snow$Response, audio_snow$Stimulus, df, MSerror, group=FALSE)  Study:  HSD Test for audio_snow$Response   Mean Square Error:  5.609524   audio_snow$Stimulus,  means                  audio_snow.Response   std.err replication snow_dry_leaves            4.933333 0.6208034          15 snow_gravel                6.866667 0.5679258          15 snow_metal                 6.333333 0.5662463          15 snow_sand                  6.733333 0.5114561          15 snow_snow                  7.333333 0.5989409          15 snow_wood                  5.066667 0.7713110          15  alpha: 0.05 ; Df Error: 84  Critical Value of Studentized Range: 4.124617   Comparison between treatments means                                Difference   pvalue sig        LCL      UCL snow_gravel - snow_dry_leaves  1.9333333 0.232848     -0.5889913 4.455658 snow_metal - snow_dry_leaves   1.4000000 0.588616     -1.1223246 3.922325 snow_sand - snow_dry_leaves    1.8000000 0.307012     -0.7223246 4.322325 snow_snow - snow_dry_leaves    2.4000000 0.071587   . -0.1223246 4.922325 snow_wood - snow_dry_leaves    0.1333333 0.999987     -2.3889913 2.655658 snow_gravel - snow_metal       0.5333333 0.989528     -1.9889913 3.055658 snow_gravel - snow_sand        0.1333333 0.999987     -2.3889913 2.655658 snow_snow - snow_gravel        0.4666667 0.994348     -2.0556579 2.988991 snow_gravel - snow_wood        1.8000000 0.307012     -0.7223246 4.322325 snow_sand - snow_metal         0.4000000 0.997266     -2.1223246 2.922325 snow_snow - snow_metal         1.0000000 0.855987     -1.5223246 3.522325 snow_metal - snow_wood         1.2666667 0.687424     -1.2556579 3.788991 snow_snow - snow_sand          0.6000000 0.982179     -1.9223246 3.122325 snow_sand - snow_wood          1.6666667 0.393171     -0.8556579 4.188991 snow_snow - snow_wood          2.2666667 0.103505     -0.2556579 4.788991


I wish to connect my Google Server in one room to a switch in another room using ethernet cat 5e cable. What is the maximum cable length I can use between both nodes to avoid high RTT?

What is the max distance for cat5e cables in 1000Mbps (1 Gigabit) Full Duplex mode?


I want to Differentiate between User defined columns and default columns for a given list  in SharePoint online using CSOM (using  Microsoft.SharePoint.Client) . I searched alot but no luck.  Anyone please suggest how to meet the above requirement or any workarounds.  Thanks in Advance.

When iterating the fields of a list how do you know which columns are yours and which are built-in ?  I know a solution for "classic" SDK using SPField.SourceId  but I can't find one for CSOM.  I thought UserCreated was the way to go for but   So how do you tell apart theirs and mine ? Using a combination of Hidden CanBeDeleted FromBaseType ? Checking for a list of special internalNames ?          ClientContext context = new ClientContext(siteUrl);         context.Credentials = creds;         Web web = context.Web;         var list = web.Lists.GetByTitle(listName);          context.Load(list.Fields);         context.ExecuteQuery();          foreach (Field field in list.Fields)         {         bool thisColumnWasCreatedByUser =                        field .FromBaseType == false &&                     //this.InternalName != "Title" && // builtin but I'd rather keep it                     field .InternalName != "_dlc_DocId" && // probably safe                     field .InternalName != "_dlc_DocIdUrl" &&                     field .InternalName != "_dlc_DocIdPersistId" &&                     field .InternalName != "Combine" && // sucks                     field .InternalName != "RepairDocument" // sucks too         }   EDIT  Mixing suggestions by Viraj Gorajia and Dikesh Gandhi, my current solution is  bool thisColumnWasCreatedByUser =  field .FromBaseType == false && (!field .SchemaXml.Contains(" SourceID=\"http")) && // remove "Title", "Combine", "RepairDocument"  (!field .EntityPropertyName.StartsWith("OData__")) // field .Sealed == true could be working too but I don't know if it could exclude valid results


I want to find out whether a package that is not installed on Ubuntu is available in my configured repositories using a shell script, preferably not one that needs to examine the output from a command to determine what is happening. I have no problems determining whether a package has been installed, but determining if it is available is another problem.

I am specifically interested in determining whether a 32-bit version of OpenJDK 8 exists in the apt/Ubuntu repos.  According to , you can install the 32-bit version of the Open JDK 7 packages via:  sudo apt-get install openjdk-7-jre:i386   How can I do the equivalent of an ls -al to see what packages exist for OpenJDK 8, and specifically, the 32-bit ones?


Can I purchase a Ubuntu system on a CD or DVD and install it myself? Or can I ship my brand new PC to you for you to perform this?

I need to upgrade my existing Ubuntu system, and I also want to install Ubuntu on a new laptop.  I would like to have an installation CD or DVD to do both of these.  Where exactly I can order or request an Ubuntu installation CD/DVD/USB?


I'm sure I've made a silly mistake here, so I would be very grateful if someone could help me clear it up! Here is my reasoning:  The Lagrangian in a spherical potential is  $$ \mathcal{L}=\frac{m\mathbf{v}^2}{2}-U(r) = \frac{m}{2}(\dot{r}^2 +r^2\dot{\theta}^2+r^2\sin^2(\theta)\dot{\phi}^2)-U(r). $$ Now $\frac{\partial\mathcal{L}}{\partial\phi}=0$, so the corresponding momentum $p_\phi=\frac{\partial\mathcal{L}}{\partial\dot{\phi}}=mr^2\sin^2(\theta)\dot{\phi}$ is constant in time. This means that the Lagrangian can instead be written  $$ \mathcal{L} =\frac{m}{2}(\dot{r}^2 +r^2\dot{\theta}^2+\underbrace{[r^2\sin^2(\theta)\dot{\phi}]}_{p_\phi}\dot{\phi})-U(r) =\frac{m}{2}(\dot{r}^2 +r^2\dot{\theta}^2)-U(r)+\frac{d}{dt}(\frac{m}{2}p_\phi \phi). $$ Since $p_\phi$ is constant the last term is a total derivative and so can be omitted completely, and the Lagrangian may be written as  $$ \mathcal{L}’= \frac{m}{2}(\dot{r}^2 +r^2\dot{\theta}^2)-U(r) $$ The Lagrangian now has $\frac{\partial\mathcal{L}’}{\partial\theta}=0$ which was not true for the original one. Something has clearly gone wrong, but where?  Also, following the same logic for $\theta$ gives that  $$  \mathcal{L}’’= \frac{m\dot{r}^2}{2}-U(r) $$  Which is also wrong - the effective potential energy has the wrong form.

If there is a system, described by an Lagrangian $\mathcal{L}$ of the form   $$\mathcal{L} = T-V = \frac{m}{2}\left(\dot{r}^2+r^2\dot{\phi}^2\right) + \frac{k}{r},\tag{1}$$   where $T$ is the kinetic energy and $V$ the potential energy, it is also possible to define the total energy $E$ of the system   $$ E = T + V =\frac{m}{2}\left(\dot{r}^2+r^2\dot{\phi}^2\right) - \frac{k}{r}.\tag{2}$$  If the angular momentum $M$ is defined by $$ M = m r^{2} \dot{\phi},\tag{3}$$ then $E$ can be written as  $$ E = \frac{m}{2}\dot{r}^2 + \underbrace{\frac{M^2}{2mr^2}-\frac{k}{r}}_{V_\textrm{eff}\left(r\right)},\tag{4}$$  where the last two terms are written as new, "effective" potential $V_\textrm{eff}\left(r\right)$.    In addition, using the definition of $M$, the Lagrangian $\mathcal{L}$ can be written as  $$ \mathcal{L} = \frac{m}{2}\dot{r}^2 + \underbrace{\frac{M^2}{2mr^2}+\frac{k}{r}}_{-V_\textrm{eff}\left(r\right)},\tag{5}$$  where the sign of $V_\textrm{eff}\left(r\right)$ has been changed, since $\mathcal{L} = T-V$. But from this argument, it appears that there are two different possible ways to construct the same effective potential. This seems to me contradictory. Where is my mistake?


Note:This question is not about how to fix a NullPointerException. This question is about why a piece of code that has been updated still generates a stacktrace in the Android Studio application for an older version.   I have a class that checks internet connectivity. This class, however, used to have an invalid piece of code, like this:  public class InternetConnectivityChecker {     private Context context;      public InternetConnectivityChecker(Context context) {         context = context;     }   I fixed this piece of code by changing it to:  public class InternetConnectivityChecker {     private Context context;      public InternetConnectivityChecker(Context context) {         this.context = context;     }   I kept getting a stacktrace, pasted below. To fix that, I decided to remove the invokation of the class altogether.  This class used to be called from SamaWebViewClient, on line 22. However, now it is not being called anymore:  public class SamaWebViewClient extends WebViewClient {     private com.sama7.sama.listeners.OnReceivedErrorListener onReceivedErrorListener;      public SamaWebViewClient(com.sama7.sama.listeners.OnReceivedErrorListener listener) {         this.onReceivedErrorListener = listener;     }      @Override     public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {             onReceivedErrorListener.onReceivedError();     }  }   However, now when I run my code in debug mode, even though I get 0 errors and 0 warnings in the Gradle Build window, this is what I see in logcat:  03-02 08:49:29.240 24373-24373/com.sama7.sama E/AndroidRuntime: FATAL EXCEPTION: main                                                             Process: com.sama7.sama, PID: 24373                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference                                                                 at com.sama7.sama.InternetConnectivityChecker.isConnected(InternetConnectivityChecker.java:15)                                                                 at com.sama7.sama.SamaWebViewClient.onReceivedError(SamaWebViewClient.java:22)                                                                 at com.android.webview.chromium.WebViewContentsClientAdapter.onReceivedError(WebViewContentsClientAdapter.java:582)                                                                 at org.chromium.android_webview.AwContentsClient.onReceivedError(AwContentsClient.java:355)                                                                 at org.chromium.android_webview.AwContentsClientCallbackHelper$MyHandler.handleMessage(AwContentsClientCallbackHelper.java:160)                                                                 at android.os.Handler.dispatchMessage(Handler.java:102)                                                                 at android.os.Looper.loop(Looper.java:145)                                                                 at android.app.ActivityThread.main(ActivityThread.java:5832)                                                                 at          java.lang.reflect.Method.invoke(Native Method)                                                                 at     java.lang.reflect.Method.invoke(Method.java:372)                                                                 at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)                                                                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 03-02 08:49:38.015 24373-24373/com.sama7.sama I/Process: Sending signal. PID: 24373 SIG: 9   Why am I not getting the latest application built and deployed to my Samsung Galaxy S5 device?

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?


$$\forall \ a, b \in \mathbb{R}, prove \hspace{5mm}\frac{|a+b|}{1 + |a+b|} \leqslant \frac{|a|}{1+|a|} + \frac{|b|}{1+|b|}$$  I decided to take different cases to solve this problem.  For $a, b \geqslant 0$ and for $a, b < 0$, the inequality is obvious as $$\frac{|a+b|}{1 + |a+b|} = \frac{a}{1+|a+b|} + \frac{b}{1+|a+b|}$$ when $a, b \geqslant 0$ and $$\frac{|a+b|}{1 + |a+b|} = \frac{-a}{1+|a+b|} + \frac{-b}{1+|a+b|}$$ when $a, b < 0$  For $a \geqslant 0, b < 0$ and $|a| > |b|$, I was able to prove the inequality. However, I'm unable to prove in the case where $a \geqslant 0, b < 0$ and $|a| < |b|$.

Prove that for every $a, b\in R\setminus\{0\}$ is correct this inequality:  $$\frac{|a+b|}{1+|a+b|}<\frac{|a|}{1+|a|}+\frac{|b|}{1+|b|}.$$


How is electrical energy converted to heat in a circuit? I read on quora and other sites that it is due to  how much resistance it receives due to colliding with atoms. However what exactly does it mean to collide with atoms? Is the kinetic energy just transferred to the atom's electrons it interacts with and does that promote the electron to a higher energy state, and when it is de-excited it releases heat in the form of infrared radiation? How does resistance explain why copper is better conductor than iron?

Ohm is defined as      "a resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere, the conductor not being the seat of any electromotive force"    according to  wikipedia page. However, I still don't understand what exactly is resistance and ohm. Does resistance decrease the amount of electrons passing through a conductor per unit time or does it decrease the energy that a single electron carries or none of them? I know what Ohm law is and I also know the mathematical background of resistance but I can not understand the logic behind it.   For example, when we talk about a conductor that should be insulated by an electrical insulator we have to know how many ohms that is needed to determine the size of the insulator for a good insulation. But I would like to know how it is determined. Thus, I would be pleased if someone could explain the logical background of resistance and ohm. Thanks.


When deleting from the review queue, it's perfectly possible to do so without leaving a form comment:       Add a comment for the author?      Leaving a comment is optional, but can help the author learn how to improve their post or avoid making the same mistake in the future.   I'd like the same option to be available (maybe as a checkbox) when voting to close as a duplicate or using a custom reason to save me the trouble of manually deleting it later.    These comments are already deletable at will, so if I'd rather they not be posted at all in some cases, I should have that option. In both cases (duplicates, custom reasons), IMO they're unnecessary:   the close review already shows duplicates in tabs for custom reasons, they should be shown at the top in review instead of hidden in an editable comment (since the custom reason itself can't be edited). (And the reason is already shown in the close vote dialog anyway, so it's not as if they vanish if the comment is deleted, or, as I am asking, not posted at all.)     TL;DR:  I'd like an option to be made available which would allow me to vote to close without leaving a comment. I'm not asking for this to be made the default, nor am I asking that the comments not be posted at all in all cases for everyone.

As far as I see the "Blatantly off-topic" flag      Blatantly off-topic (this question has nothing to do with %site topic%)    is only available for low-rep users without the close vote privilege.  What is the reason to remove this option for high-rep users? I think it could be very usefull in some cases where now we must select      Other (add a comment explaining what is wrong)    option and waste time to type obvious message for a reason.


Many times we've seen this scenario happen - a question was posted and currently doesn't meet the standard or is unclear.  A user with voting privileges sees the content, downvotes it, and moves on with their day.  They were not obligated to make comments on their downvotes (they should, but they're not required to).  However some of these questions are redeemable - sometimes the original poster would amend the question up to standard per suggestions, or sometimes they want to clarify their position with the downvoters (especially on answers) but the downvoter is already long gone from the post.  My question is thus: should those who downvote a question/answer receive notifications on new edits and comments so they can review their decisions? I think it's beneficial because:   Notifications can easily be ignored, so it's not an annoyance.     It allows the downvotee a channel to reach out to the downvoter without pestering them.   It would generally promote better voting ratio and reduce the view of "toxicity" on some of the communities.

Prologue:  This is an effort to follow up on  which is marked as a duplicate of  highly voted and status-declined feature request (although they seem to be different, one focusing on the OP and the other on the downvoter).   My New Year's resolution was to downvote more.  So on January 3rd or so, I saw a post that was low quality, and downvoted.  Two days later, I came back to see if it was ready to be deleted or had gotten piled with downvotes, to find it with a significant positive score!  At which point, I noticed that the answer had been significantly improved.  So I retracted my downvote, changed it to an upvote, and immediately resumed my dearth of downvoting again.  I think I have a responsibility to downvote bad posts, despite that oh-so-painful -1 rep penalty.  But if I am also going to have the responsibility to follow up on every downvote I cast, I'm not going to bother. I don't want my downvote to leave a residual penalty on posts that were once low quality, and I am not going to trouble myself to keep checking up on every post I downvoted.  Can a downvoter have an option to be notified when a post they voted down was edited?  I wouldn't make this an automatic thing, because not all downvoters want it, and it isn't applicable to all cases of downvoting (although  that this should be part of the responsibility of a downvoter).  Personally, I would make this a universal toggle on-off option on the user profile page, not a question-by-question option, but I don't have strong feelings about it.


Can I build a transistor through two diodes?  I am studying transistor and, from what I understand, a transistor it is two diodos, right?  I am thinking using two diode, just like this (), to make the place the transistor (e.g. BC548).  Someone already experience this?

Another form of the question is: will joining two diodes with wires (pn-np) make a transistor-equivalent?  I read that they are not equivalent, but why?


"It would have needed an exceptionally strong Confundus Charm to bamboozle that goblet into forgetting that only three schools compete in the tournament... I'm guessing they submitted Potter's name under a fourth school, to make sure he was the only one in his category..."   — Alastor Moody   I know this is a seemingly unimportant detail, but it has bothered me ever since I first read the book years and years ago. What was the name of the fake school that was written on the slip of paper to assure Harry would be picked? Has this ever been revealed?

In the Goblet of Fire, students were supposed to put their name and the name of their school in the Parchment they put inside the Goblet.  It is clearly stated that Fred wrote "Fred Weasly, Hogwarts", in his.  But when the parchments come out, the school's name isn't there. It simply says 'Harry Potter'. Why?  Since no one was surprised at the absence of school name, I don't think this was the result of Moody's Confundus charm.


I was wondering if anyone knew the meaning of the brackets that have been rotated 90 degrees in this equation:  $$\gamma(s,z) \asymp z^s \ \Gamma(s) \ \gamma^{*}(s, 0) = z^s \frac{\Gamma(s)}{\Gamma(s+1)} = \frac{z^s}{s}$$

I'm reading a  by Andrew Granville on analytic number theory.  On page 22 of the paper, there appears a strange looking symbol, undefined.  I've circled it in red in the screenshot below.    Since it's not defined in the paper, I'm assuming it must be standard notation.   From the context, I'm assuming it means something like "as compared to", or "with reference to", but that's just a guess.  Can anyone identify the symbol, even better explain what it means and/or provide a reference?  Is there a name to speak the symbol?  Thanks in advance.


I am trying to remove certain words from a dataframe column and failing miserably...  Some of my sample data:      Stock_Name Vanguard US Government Bond Index GBP Inc (Hedged) Vanguard US Government Bond Index GBP Acc (Hedged) Vanguard US Government Bond Index GBP Inc Vanguard US Government Bond Index USD Acc   The dictionary:      replace_values = {         r'\bAcc\b': "",         r'\bInc\b': "",         r'\b(Hedged)\b': "",         r'\bGBP\b': "",         r'\bUSD\b': "" }    df["Stock_Name"] = df["Stock_Name"].replace(replace_values,regex=True)    The output I am getting:  Vanguard US Government Bond Index   () Vanguard US Government Bond Index   () Vanguard US Government Bond Index   Vanguard US Government Bond Index     for some reason the parentheses are being omitted. I have tried adding '()' to my replace values dict but it doesn't seem to do anything.

I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps?


I'm writing a novel and still getting use to rules for commas. In my novel I have this:   "Well, she better not eat any of my customers,or I’ll be having cougar tonight."  does this comma before the well look correct? I'm confused because I thought you could only have commas between independent clauses but at the same time it feels right.

I am no native speaker and always confused about the comma in introductory phrases, in particular in prepositional phrases. Is there any hard rule when a comma must be set? If I make a google search for certain phrases, I often find both variants. Typical examples where I am not sure whether a comma must be set are:        First[ly][,] I must phone mother   In this case[,] we must...   For simple problems[,] the algorithm...   From Lemma 1.2[,] we obtain...   For a typical user[,] the algorithm...   In our theory[,] we...   A dark line on the horizon[,] the mountain range we were headed for seemed somehow not as threatening as when we had started out on the trip.   Avidly reading her novel[,] Jane did not notice that her stop was approaching.   To be sure[,] it is not easy to see a solution.   When you get to Rome[,] give me a ring.


I have a file with words separated by ',' on lines, every line has the same number of words, say 4. So ther are in the form  of:  something1,something2,something3,something4  I want to search for the line that contains on the 4th column exactly something4, but how do i do that if there exists another line that is something like this:  something1,something2,something3,1_something4  with grep I will get both these lines, but I only want the line that has on the 4th element exactly something4 what should I do?

I want to apply grep on particular column in column command.  myfile.txt  3,ST,ST01,3,3,856 3,ST,ST02,4,9,0234 6,N1,N101,2,3,ST 6,N1,N102,1,60,Comcast 6,N1,N103,1,2,92   My Command:  column -s, -t < myfile.txt | grep -w "ST"   Here I want to only grep the pattern ST in 2nd column. How to do this ?  Expected Result:  3       ST            ST01              3            3            856 3       ST            ST02              4            9            0234


Someone I know went into the Large Emails "folder" and cleared it out thinking that those were just duplicates. She didn't realize that she was actually deleting the emails from her many folders.  Now, all the emails are in her Deleted Items folder. Since they came from several different folders, reorganizing them back to those folders is going to be a major task.  Is there any way in Outlook 2010 to select all the emails at once and tell it to move them back to the folders they were orginally in? This in a stand-alone environement (no Exchange Server).


A trivial question, but for some reason my mind is foggy and I could use some verification. We know that the joint bivariate pmf $P[X=i,Y=j]$ can be expressed using CDFs as follows \begin{align} P[X=i,Y=j]&=P[X\leq i,Y\leq j]-P[X\leq i-1,Y\leq j]-P[X\leq i,Y\leq j-1]+P[X\leq i-1,Y\leq j-1]\\ &=\sum_{m=0,1}\sum_{n=0,1}(-1)^{(n+m)}P[X\leq i-m,Y\leq j-n] \end{align} I would like to verify that the above relationship holds for any dimension - e.g. \begin{align} P[X=i,Y=j,Z=k]=\sum_{m=0,1}\sum_{n=0,1}\sum_{l=0,1}(-1)^{(l+n+m)}P[X\leq i-m,Y\leq j-n,Z\leq k-l] \end{align}

Suppose I have two discrete-support random variables, $X$ and $Y$.   They have joint CDF $F(X,Y)$.  If I want to find  $\Pr(a \leq X \leq b , c \leq Y \leq d)$.  It is obviously not:  $F(b ,d)-F(a-1 ,c-1)$.  What is it then, in simplest terms with respect to the CDF?  I believe, for two dimensions, it is:  $F(b ,d)-F(a-1 ,d)-F(b,c-1)+F(a-1,c-1)$.  What is it for an arbitrary $d$ dimensions?


Good evening everyone.  I have this code that I slightly need to modify to make the "wave curves" as showed in photo I attach here.   \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \draw [thick, gray, ->] (0,-1) -- (0,5)      % draw y-axis line node [above, black] {$x_{3}$};              % add label for y-axis \draw [thick, gray, ->] (-5,0) -- (5,0)      % draw x-axis line node [right, black] {$x_{2}$};              % add label for x-axis  \draw [thick, black, ->] (0,0) -- (-4,4)      % draw y-axis line node [above, black] {$x^{'}_{3}$};              % add label for y-axis \draw [thick, black, ->] (0,0) -- (4,4)      % draw x-axis line node [right, black] {$x^{'}_{2}$};              % add label for x-axis      \filldraw[fill opacity=0.1,fill=blue] (0,0) -- (1,0) arc (0:135:1cm) node[midway,above,opacity=1.0]{$\theta$} -- cycle; \filldraw[fill opacity=0.1,fill=red] (0,0) -- (2,0) arc (0:45:2.0cm) node[midway,right,opacity=1.0]{$\phi=\theta-90^{\circ}$} -- cycle;  \end{tikzpicture}  \end{document}   Does anyone know if it's possible to realize something similar to the attached photo and how to do it?  Thanks a lot in advance :)

I want to sketch this figure.. if you guide me to draw one of this arrows with direction i would be grateful..


We write when we need to remember something, be it an idea, a quote or the outcome of a study.  In the second clause, the beginning is be. What is the grammatical rule behind it?

What does be it mean in this context and what kind of sentence is this? (grammatically)     There is no one in our society who is not ethnocentric to some degree, no matter how liberal and open-minded he or she might claim to be. People will always find some aspect of another culture distasteful, be it practices, a way of treating or relatives, or simply a food that they cannot manage to get down with a smile.


Is there a better way to clean the log file? I usually delete the old logfile and create a new logfile and I am looking for a shorter type/bash/command program. How can I use an alias?

I am aware of three methods to delete all entries from a file. They are  >filename touch filename1 filename < /dev/null  Of these three I abuse >filename the most as that requires the least number of keystrokes. However, I would like to know which is the most efficient of the three (if there are any  more efficient methods) with respect to large log files and small files. Also, how does the three codes operate and delete the contents?  1Edit: as discussed in , this actually does not clear the file!


I'm desperately looking for a way to enable TUN/TAP on a VPS in order to use an OpenVPN client. The VPS is based on Parallels Virtuozzo. I've been reading a ton of tutorials and forum topics, and here is the output I'm getting with the commands I often see :  lsmod | grep tun (no output)  modprobe tun FATAL: Module tun not found.    When I try to run the client, here is what I get at some point :  ERROR: Cannot open TUN/TAP dev /dev/net/tun: Operation not permitted (errno=1)   The server is running CentOS 6.7. Let me know if there is anything other piece of information I need to provide.  UPDATE : I found out that only the host should be able to help me by enabling TUN/TAP on the container. However, they don't "offer this feature" for some reason. I found a similar case here :  Do you have any suggestions?  Thanks

I'm trying to set up an OpenVPN server on my VPS for myself when I'm in public places, using this tutorial,   However whenever I try to start the server, it gives me this,  root@vps:~# /etc/init.d/openvpn start  * Starting virtual private network daemon(s)...                                                                 *   Autostarting VPN 'server'                                                                           [fail]   The log contains this  Tue Dec 11 10:53:32 2012 Diffie-Hellman initialized with 1024 bit key Tue Dec 11 10:53:32 2012 /usr/bin/openssl-vulnkey -q -b 1024 -m <modulus omitted> Tue Dec 11 10:53:33 2012 TLS-Auth MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ] Tue Dec 11 10:53:33 2012 ROUTE: default_gateway=UNDEF Tue Dec 11 10:53:33 2012 Note: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2) Tue Dec 11 10:53:33 2012 Note: Attempting fallback to kernel 2.2 TUN/TAP interface Tue Dec 11 10:53:33 2012 Cannot allocate TUN/TAP dev dynamically Tue Dec 11 10:53:33 2012 Exiting   So obviously it's something to do with the tun, but I don't understand how to fix it.  Thanks!


after install the latest stable version of Google Chrome on a fresh CentOS 7 I get this error when trying to run it as "root".  [root@ip-172-31-49-161 /]# google-chrome & [4] 11889 [root@ip-172-31-49-161 /]# [1:1:0912/031926:ERROR:image_metadata_extractor.cc(111)] Couldn't load libexif. [1:1:0912/031926:ERROR:nacl_fork_delegate_linux.cc(314)] Bad NaCl helper startup ack (0 bytes)   Do you have any idea how to solve this problem?

I am having a bad time trying to run Chrome on my CentOS 7.1 server. I know, it does not have a screen, it's a server. But I installed GNOME anyway and using VNC I can see the screen on a remote computer.  If I execute export DISPLAY=:0;firefox &  I can see the firefox running just fine!  The problem is with Chrome. I installed it on my CentOS 7.1 and when I run it as "root" (I know I shouldn't, but in this case I can only run it as root cause no other user is allowed in this server) I get error message that is WELL SPREADED on the Internet and nobody still found a good solution.  I try to run chrome with this:  google-chrome &   I get this error:  [root@ip-172-31-49-160 /]# google-chrome & [4] 11889 [root@ip-172-31-49-160 /]# [1:1:0912/031926:ERROR:image_metadata_extractor.cc(111)] Couldn't load libexif. [1:1:0912/031926:ERROR:nacl_fork_delegate_linux.cc(314)] Bad NaCl helper startup ack (0 bytes)   Unfortunatelly Chrome does not open. What am I doing wrong?  **      **


I am having an issue with what I believe is the anisotropic shading on my object. It's causing this weird radial pattern on the texture beneath it in an actual render, but it looks good in the rendered view inside the viewport. In the image, the bottom is the viewport rendered view, and the top is an actual render with the same amount of samples.

I was following  on creating a watch and noticed that when I rendered the watch, some pieces were messed up.  I'm new to 3D modeling and I've just learned Blender, I can't explain it well, so here's a picture:    Other examples:     I don't know if it's a problem with my World texture, the object, or the object's texture/material, so I can't even guess how to fix it. What causes this? Is it possible to fix it?


In some bash codes, I see an extra character is added before the string comparison. Can somebody explain the reason? if [ "x$VAR" = "xString" ]; then ... fi

I have encountered comparisions of variables to string literals multiple times over the years which had one character prefixing the variable and the literal, e.g.  if [ "x$A" = "xtrue" ]; then   in order to check whether $A is "true".  I assume this is done to achieve shell compatibility or to work around a longterm bug, an unintuitive behavior, etc. Nothing obvious comes to mind.  Today I figured I want to know the reason, but my research didn't turn up anything. Or maybe it's just me making something out of a rather frequent exposure to rare occurances.  Is this practice still useful, maybe even best?


Post transcription, introns are removed and exons are rearranged randomly. If that's the case (which it is according to the book EDEXCEL SNAB A2 topic 6) then shouldn't the protein produced be different every time? Shouldn't the order of amino acids be different? And if it is, doesn't that mean that the protein produced is different?  To quote : "When mRNA is produced, its introns are removed by spliceosomes and a different number of exons is put together at different orders which changes the sequence of amino acids in proteins."  Quote from the book:        Genes contain sections that don't code for amino acids.          These sections of DNA are called introns. All the bits that do code for amino acids are called exons.    During transcription both introns and exons are copied into mRNA.    The introns are then removed by a process called splicing -- introns are removed and exons joined forming mRNA strands. This takes   place in the nucleus.    The exons can be joined together in different orders to form different mRNA strands.         If this process happens,how can a gene code for a specific protein? This process means that exons are arranged differently, and this means that amino acids are arranged differently, and doesn't that mean that different proteins are going to be produced than the one coded for?

Are there any cases in which the splicing machinery constructs an mRNA in which the exons are not in the 5' -> 3' genomic order? I'm interested any such cases, whether they involve constitutive or alternative splicing.


I am trying to make something like this work.  string operator = "+"; int randomNumber = 1; int randomNumber2=2;  if(randomNumber+operator+randomNumber2 == 3)   But can't seem to get it to work, I also tried to do a char with no luck either.

I need to evaluate a mathmatical expression that is presented to me as a string in C#.  Example noddy but gets the point across that the string as the expression.  I need the evaluate to then populate an int.  There is no Eval() in C# like in others langugaes...  String myString = "3*4";   Edit:  I am on VS2008   Tried the Microsoft.JScript. = Its deprecated method (but still complies - warning)  However the Microsoft.JScript dll that I have doens work on      public object InvokeMember(string   name, BindingFlags invokeAttr, Binder   binder, object target, object[] args);   Complains that there is a missing ";"  go figure...  EDIT 2  Solution - was the codeDom one - it worked for as there are no security issue - only me ever going to be running the code.  Many thanks for the replies ...  And the link to the new Dragon Book  awesome   EDIT 3  Matt dataTable.Compute() also works - even better for the security conscious.  (parameter checking noted)


What crimes are punished with sentences in Azkaban? Or what must be proved in a trial to merit a stay in Azkaban other than murder?

Of all the people we know, in the books, who were sent to Azkaban, the majority are Death Eaters (Dolohov, Lucius, Crouch Jr, Bellatrix and so on) or suspected to be involved with them (Sirius, Stan, et cetera). They were imprisoned for using the Unforgivable Curses, as well as for being accomplices of a seriously dark wizard. What other crimes are Azkaban-worthy, in normal circumstances? I'm looking for anything that's been stated in the books, or on Pottermore (basically, anything 'canon'), or anything one can conclude from information in the books. I think smaller crimes are punished by imposing a fine, but what about bigger ones? Surely murder and torture (i.e. crimes against humanity) aren't the only ones punishable by imprisonment? That certainly isn't the case in contemporary Muggle society. My thoughts Off the top of my head, I can name these crimes:  Being an unregistered Animagus1 That was what Hermione threatened Skeeter with.  Trespass and robbery2 That's how Sturgis Podmore was imprisoned.   Notes  Several of the arrests in the Half-Blood Prince and the Deathly Hallows were made by an authoritarian (if that's the right word on this case) government, in the time of war. They do not count as normal.  I don't mean that there should be an answer to this question, I was wondering if it was ever addressed in the books. I certainly don't expect a list of all people sent to Azkaban, and the reasons for doing so!     1 "Well, yes," said Hermione calmly, taking a sip of her drink. "Otherwise, as you very well know, I will inform the authorities that you are an unregistered Animagus. Of course, the Prophet might give you rather a lot for an insider's account of life in Azkaban."  The Beetle at Bay, Harry Potter and the Order of the Phoenix     2 Sturgis Podmore, 38, of number two, ... charged with trespass and robbery ... sentenced to six months in Azkaban.  Percy and Padfoot, Harry Potter and the Order of the Phoenix


I try to delete a question on meta through the mobile site but it simply reloads and nothing happens. Then I switch to the full site and try again and see the following notice:     Sorry, this question has answers and cannot be deleted; flag it for moderator attention instead.   It is until then that I understand why nothing happens. Can you show this message on the mobile site as well, just like the one that shows up when you try to upvote your own question? It caused a little bit of confusion when the page just reloads.

There is some sort of delay for deletion of your own closed questions (2 days, I think) for non-mods. Now, when you try deleting a closed question on the desktop site, it nicely tells you "please wait xyz to allow for possible reopening" (in a box similar to the "please consider adding a comment explaining why you downvoted" thingy).  On mobile, it just reloads the page—there is no indicator that deletion is not allowed.  Either completely disable the delete button on mobile for closed questions, or give it a popup as well. Not letting the user know what's wrong is confusing.


I dont have a page down or page up buttons on my keyboard, and i noticed ctr+down=end ctr+up=home (at least in firefox)  Are there shortcuts for page down and page up?  (keyboard does not have a fn key like a macbook)   Solution(firefox only): space=pageDown & shit+space=pageUp

I use a MacBook pro and am using Linux Mint. I know this is an Ubuntu forum but Mint is built on top of Ubuntu so I am trying here.  The Macbook Pro doesn't have a Page Down or Page Up button. Applications such as Epiphany and Terminal use these buttons to switch between tabs. Ubuntu and Mint both use APT so I assume all applications are the same if not extremely similar. You cannot re-key-bind the terminal nor Epiphany. So I tried the Keyboard settings app and Keyboard Layout app to see if I could change the keys. This proved futile.  What I want is either to rebind the keys in Epiphany and the Terminal, or bind Page up and Page down to something else.


Is there a tool that can be used for batch checking images for corruptions such as these (in this case, occured due to error while moving file),

Sometimes when you're downloading an image and the connection breaks mid stream, you are left with a half downloaded image. If you try to view it you get the upper part of the image and the bottom part is usually coloured grey or green or some other color.  In other words, it is corrupted.  Is there a way to check whether the image is damaged in that way or otherwise corrupted?


The title is self-explanatory.  Anything of that sort  \href{run:path/to/file.pdf#chapter2}{go to chapter 2 of file.pdf}   ?

Can I create a link from one file into another one. So that when the resulting pdf files are in the same directory the link takes me from one to the other? Does another package do that?  Added on 1/20/2012, Reason for the question: I want to submit a document to an organization which wants it to be split into A.pdf for body of paper and B.pdf for the references, C.pdf etc. I assume they will reside in a common directory. They may be viewed individually or coalesced together into a single document.


This has always annoyed me. Bluetooth turns on when I boot up my laptop, and it's a real drain if I forget to turn it off. It's been a year, and I'd like to find the solution, finally, here.  Thank you :)

How can I deactivate Bluetooth on system startup?


I have a model where i need to make a lot of holes. The kind of the problem is in all of them the same. The position and size of the hole(s) is already set by a face and they should not change. So what i need to do is to punch the face through the part of the model to a backface. Here is an simplified illustration of the problem:     Update1: I don't have a separate mesh to make holes.  Update2: I have this problem probably more than 30 times in my mesh. So doing an extrusion, deleting backface, punching hole, recreating the backfaces, making the tunnel is unpythonic. Is there a shortcut for this?

How do I make a hole in an object created by me? Please help, youtube tutorials didn't help at all. Hope the image help.


I'm doing a java project and want to produce a word doc or pdf of inputted (formatted) text. I've read that I could use Apache POI xwpf, but I know infinitely more LaTEx commands than apache poi. How would I get my java program to open miketex and compile a tex file?

I want to render math formulas in my Java GUI application. I am looking for a library made for computer use, not web use, which can render TeX. I have already tried jLatexMath, but it's very slow when I use it in my application. If there are any other/better, could you point me in the right direction?


Is it possible to create a URL or hyperlink that opens up a mail search in Outlook 2010?  I often have e-mail messages associated with Outlook tasks, so I'd like to include in my task notes a URL that brings up an Outlook search for e-mail belonging to a specific category.

I'm going through a process of creating documentation from a long list of emails.  This process is ongoing and I don't have control of the input (the fact that the source is coming via email).  The documentation I am creating links to (or contains) the information from the emails.    What I've been doing is exporting the email thread to html, making available on our intranet and then linking to it in my documentation.  Sometimes new emails in the same thread come in after I create the link thus causing problems.  Also, it'd be ideal to keep the privacy of these emails and not have to repost the content.  Also, it'd be easier for me if I didn't have to export them to html.    What would be ideal is to be able to create a link to the user's own outlook email (something like outlook://search:subject:"howto create blue widgets").  This obviously assumes the user has that email thread in their inbox.  Can I do something like that?


Is there a way in the report class to change the name of a document header?  For example, change \chapter{Test Chapter} from  Chapter 1 Test Chapter   to   Part 1 Test Chapter   I don't want to use \part, just to change the name applied to the \chapter command.  Example Input:  \documentclass{report} \begin{document} \chapter{Test Chapter} Test text \end{document}   Expected Output:  Part 1 Test Chapter  Test text   Thanks!

I'd like to modify the names used to typeset some of my document elements. For example, the caption of figure floats should change from "Figure" to "Fig.", and my \tableofcontents sectioning heading shouldn't read "Contents", but "Table of Contents". How can I do that?  \documentclass{article} % \usepackage[english]{babel} \begin{document} \tableofcontents \section{foo} \begin{figure}[h] \centering \rule{1cm}{1cm}% placeholder for graphic \caption{A figure} \end{figure} \end{document}


I'm a novice in Blender and my problem is the roof isn't transparent everywhere, when I put camera in a certain angle the location of the transparent changes.  I use BlenderGuru pro lighting skies for the light.

I have a glass plane mixed with a diffuse fresnel (and a .png texture):    This glass plane shows up diffuse when viewed at an angle. When viewed straight on, it looks fine, like a regular glass plane. How can I get rid of this diffuse effect?


i am using document class book. I have tried openany, oneside, cleardoublepage  But the blank page is not removed between two lists. My lists are quite lengthy though

Please how can I delete the blank page between List of Figures and List of Tables?  I tried this:   \listoffigures  \nopagebreak[0]  \listoftables   but nothing changed. Here is my code:  \begin{document} \tableofcontents  \nopagebreak[0] \backmatter  \listoffigures \nopagebreak[0] \listoftables \newpage \clearpage{\pagestyle{empty}\cleardoublepage} \mainmatter \include{Introduction} \end{document}   I just want to delete the white page between \listoffigures and \listoftables.


There are some people who (without having a stated theory that I know of) insist that Gravity, Electricity, and Magnetism are related. Some point to symmetry in Maxwell's Equations as a potential indication of this (intuitive) connection. Is it possible that there are "Maxwell-like" equations that relate Electricity and Magnetism directly to Gravity? All forms of electromagnetic energy do interact with gravity. Are there any physicists who are working on this sort of theory?

In classical mechanics, we had Newton's law of gravity $F \propto \frac{Mm}{r^2}$.  Because of this, all laws of classical electrostatics applied to classical gravity if we assumed that all charges attracted each other due to Coulomb's law being analogous.  We can "tweak" classical electrostatics to fit gravity.  In modern physics, does the reverse work?  Can we "tweak" General Relativity to accurately describe electrostatics or even electromagnetism?


Wich are the options for Ubuntu Desktop management over network?   Not installation deployment over network. Management of more than 1000 Ubuntus desktop over network.  Something like Red Hat Satellite... to generate reports about updates, memory usage, disk usage, install software and other management tasks.

Recently I got in charge of managing 2 computer labs (currently 35 workstations, could double in a month or two) in university with total control over software stack as long as I install a bunch of commonly used scientific software (Mathematica and friends).  I plan to use Ubuntu for various reasons.   Installing Ubuntu and managing updates etc by hand is certainly an option, But I want to know if there is a more efficient way to do this stuff in and a more "Don't Repeat Yourself" manner?  Tasks   Ubuntu installation Installation (duplication) of same software stack and configuration over each workstation Keeping them updated


I wrote this really nice app that works just fine in Linux.  It uses strptime(). Windows doesn't have this.  Is there a Windows alternative for this?  My coworker needs to use this app.  (I tried googling it already to no avail)

Is there a good equivalent implementation of strptime() available for Windows?  Unfortunately, this POSIX function does not appear to be available.   - summary: it converts a text string such as "MM-DD-YYYY HH:MM:SS" into a tm struct, the opposite of strftime().


I need to find a chart of historic prices for Exide Technologies' old stock symbol: XIDE. This was the symbol of the company until its bankruptcy, after which its symbol changed to EXIDEQ.  Where can I find the stock prices of XIDE, and other delisted stocks, for free on the internet?

With services like Google Finance or Yahoo Finance it is very convenient to find the historical stock price metric of a listed company, but if the company is not listed, I can't find the data.  For example, I want to see the price metrics for Macromedia, which had been listed in 1993 on NASDAQ (MACR), then acquired by Adobe in 2005. How could I find its historical price metrics?