I'm seeing this very often recently - what does it mean?  public void IPersistenceRepository<TEntity> : IDisposable {                                                                        |                                                                        v     public IEnumerable<TEntity> Where(Expression<Func<TEntity, bool>> @predicate);  }   or  public IDomainEventHandler<TEvent> : IEventHandler {                                |                                v     public void Handle(TEvent @event);  }

Possible Duplicate:          I understand that the @ symbol can be used before a string literal to change how the compiler parses the string.  But what does it mean when a variable name is prefixed with the @ symbol?


I have below image. This is a scan paper, and when print out, it's too blur.    I want to use Photoshop for editing this image, so printer print out will be clearer. I don't know this question is suitable on on this site or not. If not, I don't know which tutorial online help me do this work. Please tell me.   Thanks :)

I'm using Adobe Photoshop.  I noticed that there are other questions similar to this one.   However, the reason I'm posting my question is, when I followed the instructions in the  about removing the background from a signature, it was not working for me on this document. I needed to select several times for each letter. Many times I was also getting parts of the background with the letters.  Is there some shortcut?  It looks like it will take me a whole day to select all the text, letter by letter.  Perhaps the reason the Magic Wand tool is not working well is because the text is handwritten and the edges are not well defined?  So, here's the picture.  (I thought I uploaded it the first time, I'm trying again now)    Basically, I would like guidance on how to remove the background and put the text on a solid white background. (If possible in an easier more efficient manner than selecting each letter one by one)  P.S. For those curious, this is a handwritten marriage document in the Hebrew language written on parchment with a quill.


Hello I have created windows tasks in the Task Scheduler in Windows 7 that executes batch files. Everything works fine, however I have a problem. I dont want the tasks to run over the weekends. How do I accomplish this?? I dont see any settings in the triggers tab of the task that allows me to do this.  Any ideas and suggestions are appreciated!

Is it possible to schedule a task only for working days (Monday to Friday)?


A friend has asked me to perform maintenance oh his computer. The described symptoms point to a performance issue with the hard drive. I want to objectively confirm this suspicion by measuring the performance of his 5400 RPM disk.  Which tools would you recommend for this job? Are there any (published) standard guideline numbers that I could use for the purpose of comparing my findings?

I'm trying to find out why my application is very slow on a certain machine (runs fine everywhere else). I think i have traced the performance-problems to hard-disk reads and writes and i think it's simply the very slow disk.  What tool could i use to measure hd read and write performance under Windows 2003 in a non-destructive way (the partitions on the drives have to remain intact)?


This is hardly a major issue, but in pursuit of standards, I noticed that the styling (and standard) of the descriptors in the closure dialog box is somewhat lower than expected:

"Should" word in italics is shifted down in the vote-to-close popup when there is at least one pending close vote.  Just have a look at this:        Now without close votes:        So the issue occurs when there is a close vote on it. It doesn't look good.    Tested on Chrome 27.0.1453.116 m, Windows XP. And it looks fine on Firefox 21.0 and Opera 12.02 (Windows XP)  Here is an example of a slightly different but obviously related problem in Windows 7 SP1 and Firefox 21.0:    This seems to have something to do with how line-height and/or margin attributes are being interpreted.  Can this be fixed?


Is there a way to stop a particular app from establishing ANY sort of outgoing connections to the internet but I still want the app to be able to use the internet when I want to but still be able to block "unverified  connections at the same time. Such a thing exists?

In Android, is it possible to block apps from accessing the Internet? Many apps will often connect to remote servers in the background, including Google's own apps or system services. Over time this can eat away at a user's data limit set by a mobile carrier. Does Android allow an app to act as a firewall whereby the user can select which apps have access to the Internet? Or does the device have to be rooted to have that ability?


Will there be any spyware be contained in the next LTS version 16.04?  I'm asking this because Ubuntu has been associated with spyware .

Richard Stallman states that Ubuntu "has installed surveillance code". See:   Is this true?   I agree with him that "Any excuse Canonical offers is inadequate....".


Suppose $a$ and $b$ are real numbers. Prove that if $a < b < 0$ then $a^2 > b^2$.   My attempt:   We know that if $x > y$, then $-x < -y$. We also know that if $x > y\ge 0$, then $x^2 > y^2$.   Now consider our example:  Given that  $a < b < 0$  $$\tag1 a<b$$  $$\tag2 -a > -b$$  $$\tag3(-a)^2 > (-b)^2$$  $$\tag4 a^2 > b^2$$  Is it correct? Any suggestions for improvement would be welcome.

Given $a > b$, where $a,b ∈ ℝ$, is it always true that $a^2 > b^2$?


I installed Ubuntu on my PC alongside Windows 10 with a USB key. When I turn on my PC it starts Windows; it gives me no choice to use Linux or Windows. What should I do?

I installed Ubuntu alongside Windows but I did not disable secure boot as someone told me it could cause problems with boot loader. So when installation finished and I rebooted, the system went straight into Windows. I went to Ubuntu IRC Support and they told me to turn off the secure boot and reinstall Ubuntu. I did that but my system still boot into windows.  This is a picture of partitions on my system:    This is my first Ubuntu install on my new laptop. I followed everdaylinux guide to install it and I used something else option.


I am just about to kill the wall of flesh and i dont want the crimson/corruption to spread over my base or jungle i am thinking that i can just put 4 wood blocks around to stop the corruption/crimson

After the Wall of Flesh, the Hallow appears and Corruption/Crimson spreads even faster.   Corruption/Crimson spreads through everything   Except Hallow  Hallow spreads through everything   Except mud (jungle) Except synthetic blocks like gray-brick  The results of Hallow and Corruption meeting are unpredictable   How can I stop them both permanently and effectively from taking over the world, considering both the top layer and underground?  (Eg, simply placing gray brick on top of the surface won't stop the underground spread?)  And, is it worth the effort?


While I expect the quick answer to be “One round is one round or one round is six seconds?” I don’t think that ‘in game’ that is really true.  There are a number of one-round effects that last for more or less than one round.  So how long does that one-round effect last?  For example: color spray states:     each creature affected by this spell is blinded until the spell ends   So when would the blinded creatures see again?

The Rage class feature of the Barbarian allows you to rage for one minute given you either took damage or attacked every round. A round is defined as a 6-second interval. So the rage can last up to 10 rounds. Now my question is, does it end at the end of your 10th round or at the beginning of your 11th round? There are other effects like that, also concentration spells with the duration of 1 or 10 minutes. Sometimes those are activated before combat starts and end during combat. In general: Does an effect/concentration end at the end of your last turn during the timespan or at the beginning of your first turn after the timespan?


I have applied for UK standard visitor visa to attend my graduation ceremony for the Postgraduate course which i have completed last year. I have submitted the invitation letter from university, flight reservation, educational certificates, hotel booking. My uncle is funding my trip i have attached his banks statement and affidavit of financial support, he is funding because  i have opened bank account two months ago so according to UKVI policy banks statements should be for last six months so for that reason i have attached my statement as well to show the proof that why my uncle is funding my trip and still got rejected. Kindly please help me related to this problem and after how many days i should re apply again and what documents i should provide because my graduation ceremony will be held on 20th July 2017.     THE DECISION      I Have refused your application for visit visa because i am not satisfied that you meet the requirements of paragraph V 4.2 - V4.10.   of appendix V: Immigration rules for visitor because:      ⦁ You have applied for a visa to visit the United Kingdom for 2 weeks. I have considered your application against paragraphs V4.2 - V   4.10.       ⦁ I note that you have previously travelled to the united Kingdom, and with your earlier application provided full details to satisfy the   Entry Clearance Officer (ECO) at that time that you had met the   requirements of the immigration Rules as a visitor; however each case   must be decided on its individual merits at the time of application.      ⦁ You state you wish to visit the UK to attend your graduation ceremony held on 18/07/2017 at ABC University. I note you have   provided a letter from the University. Whilst i acknowledge this   invite, I must be satisfied with your overall personal circumstances   and intentions.      ⦁ You state in your application you are a Voluntary/ Unpaid worker. In support of your application you have provided your bank   statement. However the documents you have provided do not demonstrate   you are involved in any volunteering or unpaid work and as such it is   not clear how you are now financially supported in Pakistan. You have   submitted a bank statement from BARC  with a latest balance of 700   pounds. However there are a number of unexplained cash deposits into   the account throughout which are not sourced and it is not clear where   these funds originate from. You state your uncle will cover your cost   of 1500 pounds towards your trip. I note you have provided a letter   from him, a copy of passport and his bank statement. However the   documents do not demonstrate his employment circumstances or his   monthly income. It is therefore not clear where the 2900 pounds held   in his bank account originate from. As such, without evidence of the   origin of this money, i am not satisfied that is genuinely yours and   available to fund the proposed visit. I have considered the evidence   and information submitted in your application but i am not satisfied   that you have accurately presented your circumstances and therefore   your intentions in applying to enter the UK. This undermines the   credibility of your application to the extent that i am not satisfied   that you are genuinely seeking entry as a visitor or intend to leave   the UK at the end of your visit. Paragraph V4.2(a) (c) (e)       Future applications      Any future UK visa applications you make will be considered on their individual merits, however you are likely to be refused unless   the circumstances of your application change.      In relation to this decision there is no right of appeal or right to administrative review.

Many of the UK visa refusals we see here share a common pattern and the prevailing reasons refer to V 4.2 (a) and (c).    I do understand that, while the applicants may describe very different individual circumstances, there's a consistent pattern and, broadly, fall into specific categories:    Credibility (lifestyle, lack of ties, visit history, lies & omissions) Funding (insufficient funds, provenance of funds, funds parking) Sponsorship (family, friends, employer)   Question: What most commonly triggers a UK visa refusal where V 4.2 (a) and (c) are given as the grounds?  Secondarily: Given that there is a clear pattern, to what extent are these refusals predictable? Does sponsorship make a difference? Is there a set of personal circumstances, however abstract, where a refusal is all but guaranteed? For example, why do those we see here on TSE who sought entry for the PLAB or British Army appear to be refused with a common theme? Is there a uniform shortcoming or is it just discrimination?   PLAB: What is about applications for a visa, for the purpose of sitting the Professional and Linguistic Assessments Board (PLAB) exam, that seem to invite refusals. After all, the test is given so that international medical graduates can show that they qualify to practise medicine in the UK. The first part, PLAB 1, can be taken in centres outside of the UK. However, PLAB 2 can be taken only in the UK. Why can't you can't get a visa just to sit the exam, promising that you'll leave immediately after?    British Army: Since Commonwealth citizens are eligible to apply online to join, even those who don't reside in the UK, why is it so difficult to get a visa just to attend an interview to see whether you are suitable? Even with an invitation from the Army, such visa applications seem to be unsuccessful. Isn't a career in the British Army a valid reason?     Lastly:  After such a refusal, what approaches would increase the chance of a successful application?


I'm studying for an upcoming exam, and have been given the following question:      For which primes p is the polynomial $f(x) = x^2 + x + 1$ irreducible in $\mathbb{Z}_p[x]$?   I think I can use Eisenstein's Criteria here, but I am confusing myself as I try to apply it. Any help is appreciated!

Find all primes $p>2$ for which $x^2+x+1$ is irreducible in $\mathbb{F}_p[x]$   Attempt. Since $x^2+x+1$ is of degree 2, it is reducible iff it has a root in $\mathbb{F}_p$. It has a root in $\mathbb{F}_p$ iff $x^3-1=(x-1)(x^2+x+1)$ has a root other than 1. The latter has a root other than $1$ iff $\mathbb{F}_p$ has elements of order $3$, which happens iff $3\mid |\mathbb{F}_p^{\times}|=p-1$, which happens iff $p\equiv 1\bmod 3$. So $x^2+x+1$ is irreducible iff $p\not \equiv 1\bmod3 $.   I am getting a different answer than my professor, who has $p\equiv 1\bmod 3$. If I am incorrect, were am I going wrong?  Update. Now I am unsure about my own reasoning. What if $1$ is a root of $x^2+x+1$? I don't know why I am considering roots of $x^2+x+1$ other than $1$ when $1$ can be a root.


I've had a look at  and read the very good answer  and I understand that signature and encryption are usually different algorithms. For clarity, here I am just talking of RSA.  For long messages usually a hash is computed, padded, and then encrypted with the private key, and sent along with the message. The receiver can decrypt the signature with the public key and compare with the hash (re)computed on the message (and verify the padding integrity).  For short messages ( m < N ), what I (still) do not understand is the need of complex algorithms like ISO/IEC 9796.  Given that encryption is not the important factor but only verification is needed, the sender could encrypt the whole message with the private key (like it is normally done for the hash). The receiver decrypts the message with the public key, gets the message and implicitly verifies the sender.  Obviously textbook RSA would be subject to existential forgery (which wouldn't be a problem with formatted messages) and maybe to multiplicative forgeries. So one has to add padding, like in standard RSA.  If there are security issues on this mechanism, for what I understand they are exactly the same than for standard signature. So the only downside is that without the public key the receiver cannot get the message.  EDIT: I'va also read the answers to  but as stated, I am asking in case of m < N.  So, are there more reasons not to encrypt the original message + some padding?

The  below illustrates the process of  a message with RSA:    As diagram shows, the message is first hashed, and the signature is then computed on the hash, rather than on the full message.  Why hash the data before signing it? Why not sign the whole message? Of course, it'll save time if you sign just the hash value, but I've heard there are also security issues with directly signing the full message. If so, what are they?


I use mac to play minecraft. But the F3 on this thing does like all windows. Is there a way to change it? and if cant is there another button that does the same thing.

I recently switched my whole system to Mac OSX (Snow Leopard 10.6) from Windows 7. Now I've installed WoW and imported my old configs/addons without any problems, besides that my keybindings from F1 to F7 are completely overriden by some Mac functions like brightness/sound/keyboard backlight etc.  How can I use my F-Keys in games?


I just thinking about the reason behind the @isTest liking, as it is admired by compiler or for some other reasons Salesforce does.

Is there any advantage to using the older testMethod keyword to identify test methods or is it better to use the @IsTest annotation?  Does the location of these test methods have any significance? E.g. Either being included within the definition of the class being tested or defined in a separate class.


The WinterBash site defines  as follows:    So why will I win that hat by posting this question, even though it is not "on the hour" right now?

Timezones... are complicated. We have full hour offsets, half hour offsets...  And time keeping isn't always accurate. So does the Hero Of Time hat assume full or half hour offsets (or literally any timezone) and how close to 7:00 at somewhere do I have to post for my hat?


Paraphrasing Griffith's: For some particle of mass m constrained to the x-axis subject to some force $F(x,t)=-∂V/∂x$, the program of classical mechanics is to determine the particle's position at any given time: $x(t)$. This is obtained via Newton's second law $F=ma$. $V(x)$ together with an initial condition determines $x(t)$.  The program of quantum mechanics is to obtain the particle's wave function $\Psi(x,t)$, gotten from solving the Schrôdinger equation:  $$i \hbar \frac{∂\Psi}{∂t} = -\frac{\hbar^2}{2m}\frac{∂^2\Psi}{∂x^2} + V\Psi .$$  This is a simple case, but it illustrates the program, and generalizes to multiple particles, 3 dimensions, spin, and magnetism easily.  What is the equivalent program of quantum field theory?  And also, what is the specific representation of the "state" within that program? For example, in quantum mechanics for 1 particle in 3 dimensions, excluding spin, $\Psi: R\times R^3 \rightarrow C $ subject to normalization constraints.  Another property of the previous two programs is that it is immediately clear how the state variables evolve numerically over time (if not calculable).  And for such a solution program, is there an algebraic derivation, the way the Galilean group provides such a derivation for the Schrôdinger equation in quantum mechanics?  I'm aware of second quantization, and that particle number changes, and I've seen various Langrangians, but only for specific cases, and these are unsatisfying compared to the seemingly generic programs of other branches.  An answer dependent on Hamiltonian mechanics, classical field theory, exterior calculus, or abstract algebra is fine.  Edit: This is not a duplicate. I've seen the other question, and it's getting at how QFT differs from single-particle QM generally. I'm asking what is the specific solution program that is just generic enough to encompass all of quantum field theory, and incidentally the mathematical structure of the instances of the state variables in it, and also incidentally whether an algebraic derivation of the program exists.

As I understand it, quantum mechanics for particles was developed to replace classical mechanics for particles. In essence, we realized that particle cannot be given an exact place and momentum but must be described using probabilities and more specifically wave functions.   Is quantizing a field the same idea? That is, suppose I am considering an electric field $\mathbf E(\mathbf x,t)$. Does quantizing a field mean that we no longer believe the field can have a definite value at points in spacetime? Does this mean we are looking to find a wave function analogue for fields?


I have a CSV file  that has following form.      I read the CSV using CSV reader. It outputs the objects in following form instead of the string.  Output  [Ljava.lang.String;@138617da  **  This is my code. What is wrong with code?     public  void readFeatures () throws IOException{             File(classLoader.getResource(filename).getFile());      CSVReader reader = new CSVReader(new FileReader(file));     List myEntries = reader.readAll();      for( int i = 0; i< myEntries.size(); i ++){         System.out.println(myEntries.get(i).toString());     }  }

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


I'm in China, so wikipedia is blocked. However, before the English wikipedia is blocked, using wikipedia dictionary already gives "wikipedia server is currently unavailable". The wikipedia dictionary still shows "wikipedia server is currently unavailable" when I turn on a VPN, configure a proxy, and went to school where wikipedia can be opened in the browser (so unblocked by a VPN). Why is this the case? How can I fix this problem?

When using Wikipedia in Dictionary.app on macOS Big Sur 11.0.1, Dictionary.app sends HTTPS requests to *.b.akamaiedge.net and is not utilizing system proxy (HTTP or socks5). How do I fix this?


user@ubuntu:~$ sudo apt update Hit:1  focal InRelease Hit:2  focal InRelease Hit:3  focal-updates InRelease Hit:4  focal-backports InRelease Hit:5  focal InRelease Hit:6  focal-security InRelease Hit:7  stable InRelease Reading package lists... Done Building dependency tree Reading state information... Done All packages are up to date. N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://as-repository.openvpn.net/as/debian focal InRelease' doesn't support architecture 'i386'  N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://as-repository.openvpn.net/as/debian focal InRelease' doesn't support architecture 'i386'>

I installed Ubuntu 18.04 and then while installing Virtualbox i get the 'i386' error message after I did:  $ sudo apt-get update Get:1 http://nl.archive.ubuntu.com/ubuntu bionic InRelease [242 kB] Hit:2 http://security.ubuntu.com/ubuntu bionic-security InRelease                                                                 Hit:3 http://ppa.launchpad.net/danielrichter2007/grub-customizer/ubuntu bionic InRelease                                          Hit:4 http://nl.archive.ubuntu.com/ubuntu bionic-updates InRelease Hit:5 http://nl.archive.ubuntu.com/ubuntu bionic-backports InRelease Get:6 http://download.virtualbox.org/virtualbox/debian bionic InRelease [4429 B] Get:7 http://download.virtualbox.org/virtualbox/debian bionic/contrib amd64 Packages [1426 B] Fetched 248 kB in 1s (209 kB/s)      Reading package lists... Done N: Skipping acquire of configured file 'contrib/binary-i386/Packages' as repository 'http://download.virtualbox.org/virtualbox/debian bionic InRelease' doesn't support architecture 'i386'   I found several answers on Askubuntu for the 'i386' message but I don't know how to apply this to my situation


Take the square $[0,1]^2$ we take $n$ random lines through the square. You can choose random lines by choosing a point on one of the sides of the squares and randomly choosing a different point on any of the other three sides and then drawing a line connecting them.   What is the probability that after $n$ of these random lines the largest region is greater than or equal to $0.5$?  Any tips or cases help, thanks.

Say you have a stick which breaks randomly into three pieces (we can choose the points randomly). What is the probability that the area is greater than or equal to $0.4$?   I can see it has something to do with Heron's formula but I just can't put t together.


I'm looking for this short story - Astronauts make an emergency landing on a spiky/needle-like surface planet which turns out to be a storage facility for alien stuff. Astronaut almost starves to death, he can't figure which of the alien stuff is edible or poisonous. Some items he opens turns out to be alien weapons. That's all I remember.   It was in a SF anthology with another short story - How's the Night Life on Cissalda by Harlan Ellison

I read this short story in about 1974 or 1975.  It was in a library book, definitely a hardcover collection of science fiction short stories.  Two men are marooned in space.  They gain access to an alien space station (or maybe some sort of emergency shelter).  They don't know anything about the aliens (there are none present; the station was either abandoned,  automated, or an emergency outpost).  The story is about them trying to figure out what the stuff in the station does, and whether any of it is food that they can eat.  The phrase "One man's meat is another man's poison" was used several times; it's the first time I ever encountered it (I was about 8-9 at the time).


why different between using nextLine or without nextLine      str==str2 is false but  str4==str5 is true   There are some Example code.  Scanner scan = new Scanner(System.in); System.out.println("Input data1"); String str = scan.nextLine(); System.out.println("Input data2"); String str2 = scan.nextLine(); String str3 = str; String str4 = "a"; String str5 = "a";  System.out.println("str==str2 : " + (str==str2)); System.out.println("str2==str3 : " + (str2==str3)); System.out.println("str==str3 : " + (str==str3)); System.out.println("str4==str5 : " + (str4==str5)); System.out.println(""); System.out.println("str.equals(str2) : " + (str.equals(str2))); System.out.println("str2.equals(str3) : " + (str2.equals(str3))); System.out.println("str.equals(str3) : " + (str.equals(str3))); System.out.println("str4.equals(str5) : " + (str4.equals(str5)));   input same data,  output  str==str2 : false   str2==str3 : false   str==str3 : true  str4==str5 : true  str.equals(str2) : true   str2.equals(str3) : true   str.equals(str3) : true   str4.equals(str5) : true

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I have a problem with my realtek network card not connecting after resuming from suspend mode.   Ubuntu 13.10 Realtek network card using the r8712u driver on an Acer Aspire all in one z5101, any help appreciated.  This is the fix for this Machine Here is a technique that sometimes works:  gksudo gedit /etc/pm/config.d/config Add a single line:  SUSPEND_MODULES="r8712u" Proofread, save and close gedit. Reboot, suspend and let us have your report.  for me the driver is r8712u. You find the driver by sudo lshw -C network  the line driver = 'the driver', the driver is what you use in that line  SUSPEND_MODULES="the driver"

I tried to post to this thread  for if I understand their question I am having the same problem, but the answer option won't work for.  After suspend, the wireless is disconnected and the only way to get it to reinitialize/be recognized is to do a full restart.  At first I thought it was my gnome-shell (for lock screen disappeared there with 13.10), but when I switched to the default Ubuntu it's still doing it and it's kinda driving me nuts for I have to reopen all my files and browsers/tabs/windows every time. I don't know how to show the terminal stuff the above asker shows, but it sounds like the same issue and it only started with 13.10 upgrade a few days ago.   Any help would be much appreciated!!! -- Thanks so much, ser.


Every time I start up my windows 10 Home edition PC, after a few minutes this thing will pop up.   I always have to close it, then go to its tray icon and close it there.  I don't want to use it. How can I stop it from starting up every day?  I use a local win10 account, not connected to online  edit: my task manager

I have Windows 10 with Office installed (utilizing Office365).  I have never installed OneDrive explicitly, but every now and then I see this popup on my laptop:    I don't want to use OneDrive.  How do I get rid of it permanently?  In Add/Remove programs I don't see an option to uninstall OneDrive.


How do I bypass the google verification on my galaxy s6 after I factory reset the phone? Had to reset the phone after an app I downloaded made my phone have a melt down causing me to reset it but now I can not move past the Google setup. When I did the hard reset I was unaware that The gmail verification would be an issue unfortunately I no longer have access to the original google account. how do i get around this so i can use my phone???

I won a Samsung Galaxy S6 Edge, signed into it with my Google account, played around with it, wiped it, and sold it.  Now the person can't get past setup because it's saying he must login with an account previously synced to the phone.   Is there anything I can do from my side to remove this lock?


I'd like to know if there is a way to automize this process. When writing the slides for my course I create a version to be displayed in class (with pause etc.), then I copy the content of my beamer presentation adding the handout option at the begin to be uploaded to the students (and save same paper).  A. Normal presentation: \documentclass{beamer}  B. Handout presentation: \documentclass[handout]{beamer}   Is there a way to automize these 2 steps? When I compile the normal presentation (A.), I want LaTeX to automatically produce a handout version (B.) too (and put it in a folder named "Handout"), besides the classical PDF output.

As someone who often gives talks abroad, I usually do not know beforehand which resolutions the projector supports. Thus, I always create both a 4:3 and a 16:9 version of my slides, using e.g.  \documentclass[aspectratio=169]{beamer}   Is there a way to create both without having to change this line? I use pdflatex.


The expression `\bf{\textbackslash [ formulae \textbackslash ]}`   the result is     The expression ‘[ formulae ]’   (don't mind for not showing the '\' expressions in the result. That's not a problem ;) )  Always the second, or closing single quote being bold.  I don't know why this happens even though the quote is outside of the \bf command :(

I want to collect the most common mistakes, misconceptions, pitfalls, etc that (La)TeX and Friends users make. Please one answer for each mistake, misconception, pitfall, etc.  I am only interested in more technical, objective cases rather than psychological, social, subjective cases.  From this complete infinite list of technical and objective cases, we can have a reference how  to teach newbies much better directly or indirectly via writing a good book.  The technical and object cases are, for example, as follows.   Beginners sometimes use $\huge E=mc^2$ with the hope they will get a huge formula. It actually does not produce the expected result. The correct way is \huge $E=mc^2$. Beginner sometimes use longtable inside table because they assume longtable is the longer version of tabular which is able to be sandwiched in table. etc.


Consider the following MWE, typeset by lualatex from TeX Live 2016:  \documentclass[paper=A4, parskip=half]{scrartcl}  % % Packages %  % Fonts \usepackage{fontspec}  % Languages \usepackage{polyglossia} \setmainlanguage{english}  % Mathematics \usepackage{mathtools} \usepackage{amsthm} \usepackage[math-style=TeX, bold-style=upright]{unicode-math} \setmathfont{Latin Modern Math} \mathtoolsset{mathic=true}  % Microtype \usepackage{microtype}  % % Document %  \begin{document} Let \(A\) and \(B\) be two sets.  The set difference, denoted \[   A \setminus B \] consists of all elements of \(A\) except those which are also elements of \(B\). \end{document}  %%% Local Variables: %%% mode: latex %%% TeX-engine: luatex %%% TeX-master: t %%% End:   The corresponding output    does not include the \setminus sign.  Is this a bug in Latin Modern?  Changing the math font to XITS Math, for example, fixes the issue.

What can i put into \setmathfont{<...>.otf} for the unicode-math package to make it all work (with XeLaTeX or LuaLaTeX)?  There are several suggestions on the  of unicode-math, but the first option is commercial, and the second and the third do not work with the following example:  % !TEX TS-program = xelatex  \documentclass{article} \usepackage{unicode-math} \setmathfont{latinmodern-math.otf} % \setmathfont{texgyrepagella-math.otf} % \setmathfont{xits-math.otf}  \begin{document} $X\setminus Y$ \end{document}   I do not get the \setminus character in the output.  The \setminus character is also missing if i do not set a math font at all (i do not know which font is used in this case).  It works with xits-math, but i do not like it.  Is it expected by the way that the \setminus character is left blank without giving any warning?


I am interested in the functional equation $$f(r \cos \phi)+f(r\sin \phi)=f(r),\qquad r\geq 0,\ \ \phi\in[0,\pi/2]\text.$$ Let's assume that $f:[0,\infty)\to\mathbb R$ is monotone. Clearly, $f(x)=ax^2$ is a solution. Are there any other solutions?

Find all such monotonous function $f:[0,+\infty)\to \mathbb R$, such that for any real $r\ge0$ and $\varphi \in \left[\frac{\pi}6, \frac{\pi}4\right]$, $$f(r \cos \varphi)+f(r \sin \varphi)=f(r)\text.$$  My work so far:  If $\varphi \in \left[\frac{\pi}6, \frac{\pi}4\right]$ then $$\frac{\sqrt2}2\le\cos \varphi\le\frac{\sqrt3}2$$ $$\frac12\le\sin \varphi\le\frac{\sqrt2}2$$  If $r=0$ then $f(0)=0$  If $\varphi= \frac{\pi}{4}$ then $$f(r)=4f\left(\frac r2\right)$$  $f(x)=cx^2$ for $x\ge0$ and $c\in\mathbb R$


If $X$ is a continuously distributed random variable and $F$ is the c.d.f. of its distribution, then $F(X)$ is uniformly distributed in the interval $(0,1).$  While i'm clear with the mathematical proof, I'm looking for an intuitive answer to this.

Let $X$ be a random variable with a continuous and strictly increasing c.d.f. function $F$ (so that the quantile function $F^{−1}$ is well-deﬁned). Deﬁne a new random variable $Y$ by $Y = F(X)$. Show that $Y$ has a uniform distribution on the interval $[0, 1]$.  My initial thought is that $Y$ is distributed on the interval $[0,1]$ because this is the range of $F$.  But how do you show that it is uniform?


What is the difference between the two types of casts available in c#?    Specifically, what is the difference between.   (int)7.6 and 7.6 as int and similar casts?

Consider the following code:  void Handler(object o, EventArgs e) {    // I swear o is a string    string s = (string)o; // 1    //-OR-    string s = o as string; // 2    // -OR-    string s = o.ToString(); // 3 }   What is the difference between the three types of casting (okay, the 3rd one is not a casting, but you get the intent). Which one should be preferred?


This is a followup to the post . When I compile my document, my bibliography sometimes exchange the name of the author with lines. One of the entries that had a line instead of the name in my original document, has name shown here. In my previous problem (linked above) the solution was a simple "switch". I have looked for the solution in the manual, but I probably do not understand where it is mentioned.  Sorry about the long MWE, but it felt necessary to add all the bib-entries to show my problem.  \documentclass[a4 paper,12pt]{report} \usepackage{graphicx}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{times}  \usepackage[english]{babel}  \usepackage[ authordate, backend=biber, natbib, maxbibnames=99, ibidtracker=false, ]{biblatex-chicago}  \addbibresource{mybib.bib}  \usepackage{csquotes}  \begin{filecontents}{mybib.bib} @BOOK{lpd,   title = {Longman Pronunciation Dictionary},   publisher = {Pearson Education Limited. Essex},   year = {2008},   author = {Wells, J.},   edition = {3rd},   date-added = {2014-02-25 15:30:14 +0000},   date-modified = {2014-04-26 18:18:22 +0000},   keywords = {wells} }  @BOOK{wellint,   title = {English intonation An Introduction},   publisher = {Cambridge University Press Cambridge},   year = {2006},   author = {{Wells, J.}},   date-added = {2014-02-05 12:51:13 +0000},   date-modified = {2014-04-25 15:24:39 +0000},   keywords = {intonasjon} }   @ARTICLE{wellstrans,   author = {Wells, J.},   title = {Transcribing Estuary English},   journal = {Speech Hearing and Language: UCL Work in Progress},   year = {1994},   volume = {8},   pages = {259-267},   date-added = {2014-01-22 13:35:58 +0000},   date-modified = {2014-04-26 18:18:05 +0000},   keywords = {wells} }  @MISC{wells1991,   author = {Wells, J.},   title = {The Cockneyfication of RP?},   howpublished = {http://www.phon.ucl.ac.uk/home/estuary/cockneyf.htm},   month = {4},   year = {1991},   date-added = {2014-04-12 17:01:31 +0000},   date-modified = {2014-04-26 18:18:13 +0000},   keywords = {wells} } \end{filecontents}  \begin{document}  Now, let's add some quotes from the different publications. Here is publication 1 \citep{lpd}, and number two \citep{wellint}. And then we add number three \citep{wellstrans} and four with a slightly different format, just because \citet{wells1991} probably would like it better, and try to compile it.  \printbibliography \end{document}

I am using the biblatex chicago package. It's producing dashes for a repeating  author in the bibliography.  I tried different solution like, for example, including  \makeatletter \AtEveryBibitem{%   \global\undef\bbx@lasthash%   \clearfield{extrayear}} \makeatother   but that does not work. How can I avoid dashes?


I have a while loop like this in my Console Application:  count = 0; while (count < 60) {    count++;  }   Okay so this loop runs very fast.  What i want is that it only adds count++ maybe once every second.   Is this somehow possible to do?

Just this - How do you add a timer to a C# console application? It would be great if you could supply some example coding.


How is $\left(\frac {p-1}{2}\right)! ^2 \equiv -1 \pmod p$. I was using this result for a proof ($x^2$ = -1 (mod p) ) and was stuck on this part. NOTE, this result is only when p is a prime of form 4k+1. note: please don't delete my question without atleast informing me of the reason.

Assume $p$ is prime and $p\ge 3$.  Through experimentation, I can see that it's probably true. Using Wilson's theorem and Fermat's little theorem, it's equivalent to saying $2^2 4^2 6^2 \cdots (p-1)^2 = (-1)^{\frac{p+1}{2}}$ mod $p$, but I can't figure out any more than that.


I'm working on a project where I'll be using VisualForce to render custom PDF service reports. So my page will take in the ID of a Service object (from Field Service Lightning) and populate all the data from there and its related records. One requirement is that we be able to take attached signature images and include them in the report.  I see there are many ways to attach files including "Notes & Attachments" and "Files". We'd prefer to use Files as it's a newer feature set. However I have only managed to do this successfully with Attachments so far. This is my working code that displays all related Attachment images:  <apex:repeat value="{!CKSW_BASE__Service__c.Attachments}" var="att">     <apex:image url="{!URLFOR($Action.Attachment.Download, att.id)}"         rendered="{!contains(att.ContentType, "image")}" /> </apex:repeat>   So you can see I grab the entire Attachments related list, I use the global $Action provider to generate a URL for the attachment, and then render it only if it is actually an image.  But what do I do if the image was attached using the Files feature (which I understand has the API name ContentVersion) instead of Attachments? What is the structure of the related lists I can use, if any, and can I fetch the URL using URLFOR rather than hard-coding /sfc/servlet.shepherd/version/download/{id}? I am not finding this to be well-documented.  EDIT: Okay I found the related list... I would have to iterate over CKSW_BASE__Service__c.ContentDocumentLinks and then get the LatestPublishedVersion property to have the ContentVersion ID. But I am stuck on finding a way to use URLFOR with this object.

How can I display an image which is stored in files?  For attachments I can use the code below, but it doen't work for files.  <apex:image id="Stat1" URL="/servlet/servlet.FileDownload?file=0698E0000008w5e" width="15" height="15"/>


input      > a='Vikas'    > echo $a     Vikas   my required output is   echo $a | <some command>  vIKAS

My question is how can I convert all text from uppercase to lowercase and vice versa? That is to change the cases of all the letters. It has to be done with a sed replacement somehow.


I'm learning about strongly stationary processes with the definition:  This implies that they have the same distribution for every $t$, I don't really understand what more "same joint distribution" adds. Could someone give a simple example where a process has the same distribution for every $t$ but not the same joint distribution for some indices?

I read that this is because the mean and variance completely specify a normal distribution. However, e.g. for a Poisson distribution the mean, variance and third moment can all be expressed with the same parameter lambda. Is this not what it means to 'completely specify' a distribution?  What is an example of two Poisson distributions having the same mean, variance and different higher moments? If we treated weak stationary as if it was strict stationarity, what would happen when we try to do time series analysis?


If the title of the magazine is plural, eg "Reflections", "Homes and Gardens" - should I write:   "Reflections" explore the issue ... or: "Reflections" explores the issue...  Is a singular or plural form correct?

1) "The book 'The Three Musketeers' is a wonderful example of..." Here we have a proper noun, a title that happens to end in a plural, and I have no sense that the verb should be plural. "Musketeers"/is seems proper/natural/correct, and 'are' not at all.   However, such certainty begins to wane in other examples: 2) "'The Heidi Chronicles' is a wonderful example of..." doesn't completely shake my confidence, but it moves the needle, at least a little bit. But, practically speaking, I wouldn't have a second thought about correcting a student who used 'are' instead of 'is'.  Here's the one that really bothers me: 3a) " 'The Basement Tapes' are a wonderful example of..." I don't think this sounds any less proper/natural/correct than 3b) " 'The Basement Tapes' is..." In fact, 3a seems less awkward than 3b.  Why?


Two values, $x$ and $y$ are selected at random and independently of each other from the interval. What is the probability.   The only idea I have thought of is using BinomPdf, but I still don't know how to implement that into this.  This is a question I am solving on my own that I have discovered. If you send the answer and work it would not assist me cheating or anything malicious.

Two numbers are chosen randomly and independently from the unit interval $(0,1)$.  What is the probability that they differ by more than $\frac{1}{2}$? Hint: Think of the $2$ numbers chosen as coordinates in the Cartesian plane. Draw a square with vertices at $(0,0)$,$(1,0)$,$(1,1)$, and $(0,1)$. Allowable choices for the $2$ points lie below the line $y=x-\frac{1}{2}$ or the above $y=x+\frac{1}{2}$. Find the combined area of these regions.  I need help on this. I know what $y=x-\frac{1}{2}$ and $y=x+\frac{1}{2}$ looks like but I am not understanding the problem as a whole


In CS:GO there are a couple of rules I know for awarding MVP, such as a bomb plant and 1 kill giving an MVP over 2 kills, etc.  But when 2 players get the same amount of kills, how is the MVP rewarded? Is it based off the amount of damage?

This hasn't been asked yet, but what determines how or who gets an MVP award in CS:GO? After a match, there's always a little blurb that first states who got MVP first, and then a random fact (Player X got Y knife kills, Player X lasted Y rounds without dying, etc.).  Do these two factors both "factor" into getting an MVP award? Is it a set percentage of enemies you kill? Is there a priority list (ie, planting bomb, defusing, etc.)?


Find out the number of real roots of equation $f'(x) = 0$, where    $$f(x)=(x-1)(x-2)(x-3)(x-4)(x-5)$$    How can I differentiate this function without expanding it to the polynomial form. Am I underestimating some theory of equation concept associated with it? (I know the product rule approach and solving by simplifying but I want to know is there any other way to solve it)

Let   $$f(x) = (x-1)(x-2)(x-3)(x-4)(x-5),\quad -\infty< x<\infty.$$   The number of distinct roots of equation   $$\frac{d}{dx}f(x) = 0$$   is exactly ?     The only method that I know is to multiply and then find the derivative of function then apply Sturm's theorem but it seems vague when you have to solve the question in 3 to 5 minutes . So you are requested to suggest a plausible alternative approach.


Hi Have a java class with two methods as below.  public class HelloWorld {     public static  void main(String[] args)     {         String a=null;         returnOriginalString(a);         System.out.println(a);         a="Hello";         System.out.println(a);     }      private static void returnOriginalString(String a)     {         a="Hello World";     }   }   when i print the above message i still get String a as null even after changing the string in second method.And one more thing if i update the string in same method it returns the correct value.How can i update the value of a without using any String methods.?

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


I have the following code inside a backbone view:  var BookView = Backbone.View.extend({  initialize: function() {     this.render(); },  render: function() {    this.model.fetch({     success : function(model, resp, opt) {        alert(this.$el.html() ); //THIS ONE DOESN'T WORK?     }   });   alert(this.$el.html() ); // THIS ONE WORKS FINE }  });   I have two alert(this.$el.html() ); calls, one outside the fetch, and one inside. But for some reason, the one outside the fetch call works, but the one inside the fetch call returns an error:  Uncaught TypeError: Cannot read property 'html' of undefined

I just came across an interesting situation in JavaScript.  I have a class with a method that defines several objects using object-literal notation.  Inside those objects, the this pointer is being used.  From the behavior of the program, I have deduced that the this pointer is referring to the class on which the method was invoked, and not the object being created by the literal.    This seems arbitrary, though it is the way I would expect it to work.  Is this defined behavior?  Is it cross-browser safe?  Is there any reasoning underlying why it is the way it is beyond "the spec says so" (for instance, is it a consequence of some broader design decision/philosophy)?  Pared-down code example:  // inside class definition, itself an object literal, we have this function: onRender: function() {      this.menuItems = this.menuItems.concat([         {             text: 'Group by Module',             rptletdiv: this         },         {             text: 'Group by Status',             rptletdiv: this         }]);     // etc }


$f_n$ be a sequence of differentiable functions on $[a,b]$ such that $f_n(x)\rightarrow f(x)$ which is riemann integrable consider the statements    $f_n$ converges uniformly.  $f_n^{'}$ converges uniformly. $\int_{a}^{b}f_n\rightarrow \int_{a}^{b}f$ $f$ is differentiable.   we need to find out which of the statement is not true.

Let $f_n$ be a sequence of differentaible functions on $[0,1]$ to $\mathbb{R}$ converging uniformly to a function $f$ on $[0,1]$, Then    $f$ is differentiable and Riemann integrable there $f$ is uniformly continuous and R-integrable $f$ is continuous, need not be differentiable on $(0,1)$ and need not be R-integrable on $ [0,1]$, $f$ need not be continuous.   Well I think 2 is only correct statement  as every $f_n$ are differentiable on $[0,1]$ hence uniformly contnous, and as they converge uniformly to $f$ on $[0,1]$ so $f$ is uniformly continuous and every continuous function is rieman integrable..Am I correct?


I want to read the name entered by my user using C programmes.  For this I wrote:  char name[20];  printf("Enter name: "); gets(name);   But using gets is not good, so what is a better way?

What is the simplest way to read a full line in a C console program The text entered might have a variable length and we can't make any assumption about its content.


Is $Hom_\mathbb{R}(\mathbb{R},\mathbb{R})$ (linear transformations) = $Hom(\mathbb{R},\mathbb{R})$ (morphisms of abelian groups)? No hypothesis of continuity is assumed.  Obviously $Hom_\mathbb{R}(\mathbb{R},\mathbb{R}) \subseteq Hom(\mathbb{R},\mathbb{R})$.

What is an example of an abelian group homomorphism from $\mathbb{R}$ to $\mathbb{R}$, respecting addition, that is NOT a linear transformation?  I'm trying to understand to what extent the scaling condition for the linear transformation is necessary. For $\mathbb{Q}$ vector spaces, maps that preserve addition also preserves scaling.  It seems the situation is more complicated for $\mathbb{R}$.  I guess I can "choose" a basis of $\mathbb{R}$ as a $\mathbb{Q}$ vector space and go from there, but are there any explicit examples, preferably without using the Axiom of Choice?   More generally, is there a description of the group of abelian group homomorphisms from $\mathbb{R}^n$ to $\mathbb{R}^m$?


Voltage source as we know is the battery but what is the current source? Is it just a voltage source converted to a current source on paper to simplify the computation of the circuit or it really exists and if it exists what is its example ?

What I understood from the definition of current sources is that it is a source which supplies a constant current across a load no matter how the other parameters (like resistances for example) in the circuit are changed. Am I right?  If I'm right, what is an example of a current source used in a practical circuit?   Wikipedia gave the example of a  as a constant current source. (I didn't read the article, because there was a note that the section appeared to contradict itself. I didn't want to get confused.)  I can think of voltage sources - for example a battery which has a constant potential difference across its ends irrespective of the changes in the circuit it is connected to, but I cannot think of a current source. Any example I can think of involves change in the current when the resistances are changed.


I just got a Lenovo ideapad 520, which includes a fingerprint scanner. It works fine for Windows, but when using Fingerprint GUI it simply doesn't detect the device. So I'm assuming I need a driver for this device, but I can't find any drivers online.  Does anyone know how to make this work in ubuntu 16.014?

I have a  with a fingerprint reader:    How to make Ubuntu recognise it and use it for login?  I already tried:  sudo add-apt-repository ppa:fingerprint/fingerprint-gui sudo apt-get update   ... but this GUI did not recognizes my device. Does anyone knows any other option?


Let $R=\prod_{n\in\mathbb{N}}\mathbb{Z}$ and $M$ be $R$ regarded as $R$-module is usual way.     Then the submodule $N=\bigoplus_{n\in\mathbb{N}}\mathbb{Z}$ is not finitely generated   Hint: for every $n\in\mathbb{N}$, $e_n=(0,…,0,1,0,…)\in N$ (the $1$ is on the $n-$th position).  Please help me to prove this result. Thanks in advance

Let $R=\prod_{n\in\mathbb{N}}\mathbb{Z}$ and $M$ be $R$ regarded as $R$-module is usual way.  The submodule $N=\bigoplus_{n\in\mathbb{N}}\mathbb{Z}$ is it finitely generated?  Thanks


I want to write a recursive function p() that takes a list and returns a list of all permutations of the input list.  Ex.  >>>permutations([1, 2,3]) [[1, 2,3],[2, 1, 3],[2, 3, 1],[1, 3, 2],[3, 1, 2],[3, 2, 1]]   I want to recursively call on a sublist l[1:] for all permutations of all elements of the original input list except the first element, l[0], and then generate the permutations of the original list by adding l[0] to those permutations.  So far, I have  def p(list):     if len(list)==1 or 0:         return list     result = []     for i in list[1:]:         result.append(i + list[0])     result += [list]     return result   But I know something is wrong.... help please?

How do you generate all the permutations of a list in Python, independently of the type of elements in that list?  For example:  permutations([]) []  permutations([1]) [1]  permutations([1, 2]) [1, 2] [2, 1]  permutations([1, 2, 3]) [1, 2, 3] [1, 3, 2] [2, 1, 3] [2, 3, 1] [3, 1, 2] [3, 2, 1]


If a product is a multiple of $4$, I conclude that one of the numbers is a multiple of $2$ the following way: If $$ab \equiv0\pmod 4$$ then $$ab = 4X = 2(2X) = 2Y$$ (where $Y = 2X$) This implies that either $a$ or $b$ is a multiple of $2$ so $a$ or $b$ is even. My question is if this approach is correct or there is a more "formal" way to do it. Additionally what other conclusions can we draw by knowing that $ab$ is a multiple of $4$?

We have $q, p$ prime and $tq = (p-1)(p+1)$ for some positive integer $t$. The book I'm reading says that because $q$ is prime, it divides $p-1$ or $p+1$.   Question: Why exactly does it matter that $q$ is prime here?


So, does my 6-yr old Core-2 Duo 32-bit processor system work best with the 32-bit distro, or will the 64 bit version work?

What is the difference between 32-bit and 64-bit Ubuntu? I've heard the 64-bit platform performs better and can detect more than 4GB of RAM. Also, while some apps haven't ported to 64-bit yet, ia32-libs lets a 64-bit machine run them.  If so, why not promote 64-bit over 32-bit?


I am given this problem, and the solution reasons differently from me and obscurely, to me     Let $G$ have order $30$. Show that it is not simple.   The solution is apparently     So, what I don't undestand is, say $n_3=10$ for a contradiction. This tells me that there are $10$ distinct Sylow $3$-subgroups. Now Since each have prime order $3$, they are all cyclic. By distinctness, each need to have a different generator or they will have identical elements. This simply tells me that $G$ has at least $10$ distinct elements that have order $3$. Period.  Why $20$? In a similar manner, I don't understand where the $4$ came in for $n_5$. It says "we use Lagrange" but how? Take $P_j$ for the $j$th Sylow $5$ subgroup then simply, Lagrange tells us merely that $30=6 \cdot |P_j|$.  So there are $6$ different left or right cosets of $P_j$ by $G$. Period.  I can infer nothing more or anything close to what the solution is saying, very obscure. Please help    Have been linked to an almost identical problem, and I read through the solutions given. Now, I think I would like to still ask "why does the nontrivial elements of a cyclic group always generate the group?" Trying it out with small groups it turns out true but is there a rigorous proof of it?  And also, still, why is Lagrange showing up here?

I have this following question from my class note on Sylow Theorem:     Show that a group of order 30 can not be simple.   For that I know the followings: (1) A simple group is one that does not have non-trivial normal group,  (2) Group $G$ is p-group if there exists an integer $e$ such that $|G| = p^e,$  (3) A $p$-subgroup $H$ of $G$ is called Sylow p-subgroup of $G$ if $p \nmid |G/H|,$ and finally  (4) A subgroup $H$ of $G$ is a Sylow p-subgroup if there exist integers $e$ and $m$ such that $|G| = p^em,$ and $(e, m) = 1,$ and also $|H| = p^e,$  but unfortunately I don't know how to weave them into a solution, any help would therefore be very much appreciated. Thank you for your time and help.  PS. If you have choices of elegant versus dummy down-to-earth solutions, do please give me the latter. I know it would be tedious for you but you have a slowpoke turtle down here. Thank again for your patience.  POST SCRIPT : ~~~~~~~~~~~~~~~~~~~~~~~  I came across a very simple solution by John Beachy , consisting of only 2 lines, which I adapted to fit group order of 30:  EDIT (j.p.) Unfortunately the linked solution cannot be easily adapted to this case here. I kept the text as far it was correct.  (1) Recall Sylow's Theorem: If $|G| = p^em; p, e, m \in \mathbb Z^+; (p, m) = 1;$ the number of $Syl_p (G) = s$, then $s \equiv 1\pmod p$ and $s \mid m.$  (2) For $|G| = 5 \cdot 2 \cdot 3$, suppose that $p = 5, e = 1$ and $m = 6.$ Therefore $s \equiv 1\pmod 5 $ and $s \mid 6,$ thus $s = \{1, 6 \}$. The 5-Sylow subgroup is normal if and only if $s=1$, and in this case $G$ is not simple. (3) Now look at .  Hope this will be useful for some of you and thank you very much for those of you who have helped me.


Let $A \in \mathbb C^{m\times m}$ and $B \in \mathbb C^{n\times n}$, and let $C=\begin{pmatrix} A & 0 \\ 0 & B\\ \end{pmatrix} \in \mathbb C^{(m+n)\times (m+n)}$.   Calculate the minimal polynomial of $C$ based on the minimal of $A$ and the minimal of $B$.  Prove that $C$ is diagonalizable if and only if $A$ and $B$ are.   The attempt at a solution  I have no idea how to prove 1). For 2) I got stuck in a lot of parts:  $\Leftarrow$ If $C$ is diagonalizable, then $C=P^{-1}DP$ where $D$ is a diagonal matrix. Somehow, I must construct from D two diagonal matrices $D_1 \in \mathbb C^{m\times m}$ and $D_2 \in  \mathbb C^{n \times n}$ and two invertible matrices $Q$ and $S$ so that $A=Q^{-1}D_1Q$ and $B=S^{-1}D_2S$, I don't know how to construct all these matrices.  $\Rightarrow$ Suppose $A$ and $B$ are diagonalizable, so $A=Q^{-1}D_1Q$ and $B=S^{-1}D_2S$, with both $D_1$ and $D_2$ diagonal matrices. My guess is $C$ can be written as   $\pmatrix{Q^{-1}&0\\ 0&S^{-1}}\pmatrix{D_1&0\\ 0&D_2}\pmatrix{Q&0\\ 0&S}$.   Now, I would have to prove that $\pmatrix{Q^{-1}&0\\ 0&S^{-1}}\pmatrix{Q&0\\ 0&S}=Id_{m+n}$ and that $C=\pmatrix{Q^{-1}&0\\ 0&S^{-1}}\pmatrix{D_1&0\\ 0&D_2}\pmatrix{Q&0\\ 0&S}$ in order to show $C$ is diagonalizable.  I would appreciate help in all these points where I am stuck and any suggestion or hint with regard to 1.

I am trying to prove that:  The matrix $C = \left(\begin{smallmatrix}A& 0\\0 & B\end{smallmatrix}\right)$ is diagonalizable, if only if $A$ and $B$ are diagonalizable.  If $A\in GL(\mathbb{C}^n)$ and $B\in GL(\mathbb{C}^m)$ are diagonalizable, then is easy to check the $C\in GL(\mathbb{C}^{n+m})$ is diagonalizable. But if I suppose that $C$ is diagonalizable, then exists $S = [S_1, S_2, \ldots, S_{n+m}]$, $S_i\in\mathbb{C}^{m+n}$, such that $S^{-1}CS = \mbox{diag}(\lambda_i)$ . Now $CS_i = \lambda_iS_i$, and  if $S_i = \left(\begin{smallmatrix}x_i\\y_i\end{smallmatrix}\right)$, $x_i\in\mathbb{C}^n$ and $y_i\in\mathbb{C}^m$, then $$Ax_i = \lambda_ix_i\quad\mbox{ and }\quad By_i = \lambda_iy_i.$$ So, if I can justify that $\{x_1,\ldots,x_{n+m}\}$ have exactly $n$ linear independent vectors and $\{y_1,\ldots,y_{n+m}\}$ have $m$ linear independent vectors, I will prove that $A$ and $B$ are diagonalizables, but I don't know how to prove that? Please, anyone have an idea? Thanks in advance.


How far does gravity's influence extend?  I've recently (re-)seen 'The Universe' season 1 where it's said that 'take these two dice, place them perfectly still in empty space 1 inch apart and within an hour they'll touch due to their gravitational attraction'.  I get the explanation and it makes sense.  Imagine a universe that has NOTHING AT ALL in it (except the properties of spacetime as we know it, static (therefore devoid of dark energy/matter) and the two die (dice)) - placed an inch apart, they'd eventually touch, a metre apart would they still eventually touch? a kilometre? A mile? A light year? xxx light years?  i.e. if there were no other gravitational influences, would the dice eventually touch if they were placed at opposite sides of the visible universe (given that the extended un-visible universe were also devoid of any mass)?  I believe yes as Newtonian physics states the attraction is the inverse square of distance - the attraction would be almost infinitely small, but surely there would be some and would take 'some time' to touch.

Lets say that there are only two bodies in the universe, 65 kg each. Other than that the universe is completely empty, no neutrons, no photons, no dark energy/matter, not even neutrinos (that is to make things less complicated. If the loss of other things leads to something like the universe exploding like a bubble at the speed of light or something, you can change these parameters. I'm mainly concerned about gravity here). Those two bodies are placed apart from each other at the distance of the observable universe. Will they start moving into each other? Will they collide? (Optional question: If so, with how much speed will they collide?)


I want to know good books I can  use to learn real analysis by myself. I only have the upcoming Christmas holidays were I get 2-3 weeks off. Any suggestions?

Does anyone have a recommendation for a book to use for the self study of real analysis? Several years ago when I completed about half a semester of Real Analysis I, the instructor used "Introduction to Analysis" by Gaughan.   While it's a good book, I'm not sure it's suited for self study by itself.  I know it's a rigorous subject, but I'd like to try and find something that "dumbs down" the material a bit, then between the two books I might be able to make some headway.


Consider a system having spherical symmetry filled with gas. If it expands or compress, there is some work done by system or surroundings, respectively, according to the equation $W=nRT\log(v_2/v_1)$. But the coordinates of centre of mass of system is same at the centre of sphere, so according to original definition of work ($W$ equal to force times displacement) it should be zero. I can't understand where is the mistake.

Take a sponge ball and compress it. The net force acting on the body is zero and the body isn't displaced.  So can we conclude that there is no work done on the ball?


I want to install npm. I've updated everything but I can't fix the problem.   The message I get is:  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  npm : Depends: node-gyp (>= 0.10.9) but it is not going to be installed E: Unable to correct problems, you have held broken packages.   Could you help me?

After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


so please bear with me on this.  I struggle some in understanding certain aspects of the concept of inheritance.  As such, I was wondering, what would be the difference between implementing one class, say "Child", as the child of another, say "Parent", versus simply making "Child" create and utilize a "Parent" object within itself?  For example, given the parent class as:  class Parent:     def __init__(self, arg):         self.arg = arg      def parent_method(self):         print(self.arg)   What would be the difference between making and implementing a child class:  class Child(Parent):     def __init__(self, arg):         super().__init__(arg)  Child('foo').parent_method()   Versus:  class Child:     def __init__(self, arg):         self.parent = Parent(arg)      def call_method(self):         self.parent.parent_method()  Child('foo').call_method()   Both of which simply print:  foo   Is the only difference here syntactical? I mean, it definitely seems more efficient to use inheritance here, but is there something else I'm missing?  Thanks!

There are two schools of thought on how to best extend, enhance, and reuse code in an object-oriented system:   Inheritance: extend the functionality of a class by creating a subclass. Override superclass members in the subclasses to provide new functionality. Make methods abstract/virtual to force subclasses to "fill-in-the-blanks" when the superclass wants a particular interface but is agnostic about its implementation. Aggregation: create new functionality by taking other classes and combining them into a new class. Attach an common interface to this new class for interoperability with other code.   What are the benefits, costs, and consequences of each? Are there other alternatives?  I see this debate come up on a regular basis, but I don't think it's been asked on  Stack Overflow yet (though there is some related discussion). There's also a surprising lack of good Google results for it.


I thought I know how to add pagination to a custom loop and I've seen these questions and tutorials:        but for some reason it doesn't work at this time. I created myfile.php, named it to "My Page Template" and set that to be my front page in Admin Panel > Settings > Reading.  $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;  $args = array(     'post_type' => array('my_custom_post_type'),     'paged' => $paged,     'posts_per_page' => 3,     'ignore_sticky_posts' => 1 );  $wp_query = new WP_Query( $args ); var_dump($wp_query); if($wp_query->have_posts()) :     while($wp_query->have_posts()) : $wp_query->the_post();         // show post     endwhile; endif;  next_posts_link('Next posts');  wp_reset_query(); wp_reset_postdata();   What happens:   Front page shows 3 posts as expected. "Next posts" link is shown and points to  as expected. While I'm on  it shows the same set of posts and "Next posts" link points to  which is not what I want. var_dump($wp_query) shows public 'max_num_pages' => float 8. var_dump($wp_query) shows public 'found_posts' => string '24' (length=2). var_dump($wp_query) shows public 'is_paged' => boolean false. var_dump($wp_query) shows 'paged' => int 1 (when I'm on page number 2). When I'm renaming $wp_query to $my_custom_query then "Next posts" link doesn't show at all.   Is there anything else I should do here?  UPDATE: I managed to set proper $paged by changing $paged = (get_query_var('paged')) ? get_query_var('paged') : 1; to $paged = (get_query_var('page')) ? get_query_var('page') : 1; but it still shows a wrong navigation link.

I have added a custom/secondary query to a template file/custom page template; how can I make WordPress use my custom query for pagination, instead of using the main query loop's pagination?  Addendum  I have modified the main loop query via . Why isn't pagination working, and how do I fix it?


I have this problem:   Show that $(1093)^2|2^{1092}-1$.   By this | I mean divide. I would like to write here my progress but I have absolutely no clue how to do show that it divides. Any ideas? Thanks

I can't solve this problem; it may be easy though.  Is the number $2^{1093} -2$ a multiple of $1093^2$?  I do appreciate any kind of help.


There is a grade-school explanation of how a wing works that goes approximately like this (although I'm leaving out an erroneous bit):     Because of the geometry of the way the wing meets the air, air accelerates as it goes over the top of the wing. There is something called Bernoulli's Principle that says that the pressure of a fluid decreases as its velocity increases. Because the pressure against the top is less than the pressure against the bottom, there is lift.   The oft-included erroneous bit is a claim about why the air speeds up over the top. The claim is that the air along the top has to make it over in the same length of time that it would have taken to go along the bottom. Since it has a longer trip over the top, the story goes, it has to go faster. This is not the right reason at all. There is no rule  of equal transit time and, in fact, the air along the top of the wing takes less time to get to the trailing edge.  People often point to that error and say it shows that the Bernoulli effect is not a correct explanation for flight. For instance,  makes the assertion that the Bernoulli effect is "at best a minor contribution to the actual lift", and none of the answers contradict this. But seems to me that the true situation only makes the Bernoulli effect even more important, because the acceleration of the air stream is greater than you would think if you believed the equal-transit-times story. Why is this wrong?  I also hear that it isn't the Bernoulli effect, it's that the wings redirect the air downwards. But it does not seem to me that those two explanations are mutually contradictory. If they are, I would like to understand that as well.

What aerodynamic effects actually contribute to producing the lift on an airplane?  I know there's a common belief that lift comes from the Bernoulli effect, where air moving over the wings is at reduced pressure because it's forced to travel further than air flowing under the wings. But I also know that this is wrong, or at best a minor contribution to the actual lift. The thing is, none of the many sources I've seen that discredit the Bernoulli effect explain what's actually going on, so I'm left wondering. Why do airplanes actually fly? Is this something that can be explained or summarized at a level appropriate for someone who isn't trained in fluid dynamics?  (Links to further reading for more detail would also be much appreciated)


\documentclass{article}  \usepackage{amsmath} \begin{document}  $$\sqrt{\sum_{n=1}^\infty \frac{1}{n^2}}$$  \end{document}     The top left part of the root is not aligned with the rest. How do I fix it?  EDIT: I forgot to add that I have the old root setup in preamble, but the break occurs with or without the closed root.

When the height of the radicand exceeds a certain threshold, LaTeX replaces the check-sign-like part of the root sign with a more vertical one. This behavior has a flaw: The vertical replacement part does not align properly with the vinculum (the horizontal bar). For example,  \documentclass{article} \begin{document} \[ \sqrt{\sqrt{\sqrt{\sqrt{\sqrt{\sqrt{\sqrt{}}}}}}} \] \end{document}   produces  .  I've found a few related questions here on Stack Exchange. The question  is nominally about LuaLaTeX, but the first comment, by user egreg, seems to imply that the question is related to mine. The comment blames the PDF rendering, and there may be some truth to that — the misalignment seems less noticeable to me on a high-density screen (eg. the retina MacBook Pro). However, it's not a problem with any single PDF viewer: I've seen the misalignment in Latexian, Preview, and Skim on OS X, in Adobe Reader on Windows, and on a printed copy.  The solitary answer to that question, by the way, doesn't seem to relate my problem.  The misalignment is also evident in the question . Its solution produces a slanted radical, but leaves a noticeable gap between the two components of the radical.  Does anyone else see the misalignment? Any idea what the underlying cause is? And are there any workarounds?


If my laptop has an available RAM of 8GB how can I can make the available RAM to be increased to say 8+128 GB. I am not sure if this could be done, but I guess there are devices like RAID servers etc which when attached to the computer will provide the computer with more RAM. So are there such devices available? What else is required to enable them to increase a computer's RAM ie. can I attach it by USB and what softwares are required (among other things)?

Is USB RAM or a USB processor a feasible concept for development?


Suppose there's a file that keeps appearing in my home directory automatically even after I delete it. Knowing nothing more about it, is there a way to figure how what keeps putting that file there? Is there a way to track down the program/process that creates it?

Three files have suddenly appeared in my home directory, called "client_state.xml", "lockfile", and "time_stats_log". The last two are empty. I'm wondering how they got there. It's not the first time it has happened, but the last time was weeks ago; I deleted the files and nothing broke or complained. I haven't been able to think of what I was doing at the time reported by stat $filename. Is there any way I can find out where they came from?  Alternatively, is there a way to monitor the home directory (but not sub-directories) for the creation of files?


I'm trying to create a tkinter program and I would like to know if tkinter has a OnQuit function or something similar. I would just like to know when the user quits the window.

How do I handle the window close event (user clicking the 'X' button) in a Python Tkinter program?


I am working with my document class set as [twocolumn]{article} and all is working well however I would like to know if it is possible to use the whole page witdth for text within the document.  I have tried using \centerline and center to try and nudge the text however they only centre to the middle of the column (as expected).  I also cannot use multcols so I am stuck to whatever is possible with twocolumn.    Edit:  \documentclass[twocolumn]{article}  \usepackage[italian]{babel} \usepackage{cuted} \usepackage[T1]{fontenc} \usepackage{varwidth}  \AfterEndEnvironment{strip}{\leavevmode}  % Allow me to use \newpage to swap sides. \makeatletter \renewcommand*\cleardoublepage{\clearpage\if@twoside   \ifodd\c@page \hbox{}\newpage\if@twocolumn\hbox{}%   \newpage\fi\fi\fi} \makeatother  \begin{document}  \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Fare}} \begin{description} \item io faccio \item tu fai \item lui/lei fa \item noi facciamo \item voi fate \item loro fanno \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Andare}} \begin{description} \item io vado \item tu vai \item lui/lei va \item noi andiamo \item voi andate \item loro vanno \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Potere}} \begin{description} \item io posso \item tu puoi \item lui/lei può \item noi possiamo \item voi potete \item loro possono \end{description} \end{minipage}  \vspace{0.5cm} \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Leggere}} \begin{description} \item io leggo \item tu leggi \item lui/lei legge \item noi leggiamo \item voi leggete \item loro leggono \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Scrivere}} \begin{description} \item io scrivo \item tu scrivi \item lui/lei scrive \item noi scriviamo \item voi scrivete \item loro scrivono \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Parlare}} \begin{description} \item io parlo \item tu parli \item lui/lei parla \item noi parliamo \item voi parlete \item loro parlano \end{description} \end{minipage}  \vspace{0.5cm} \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Sapere}} \begin{description} \item io so \item tu sai \item lui/lei sa \item noi sappiamo \item voi sapete \item loro sanno \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Conoscere}} \begin{description} \item io conosco \item tu conosci \item lui/lei conosce \item noi conosciamo \item voi conoscete \item loro conoscono \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Pensare}} \begin{description} \item io penso \item tu pensi \item lui/lei pensa \item noi pensiamo \item voi pensate \item loro pensano \end{description} \end{minipage}  \newpage  \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Capire}} \begin{description} \item io capisco \item tu capisci \item lui/lei capisce \item noi capiamo \item voi capite \item loro capiscono \end{description} \end{minipage}% \begin{minipage}[t]{.165\textwidth} \textsc{\textbf{Studiare}} \begin{description} \item io studio \item tu studi \item lui/lei studia \item noi studiamo \item voi studiate \item loro studiano \end{description} \end{minipage}  % Adding a strip environment here breaks the layout. % This is where I want my full-page text.  \end{document}

I'm posting today because I would like to reduce white space in a document I'm writing. The content is two-columns but I have floating tables that span across both columns (table*).   At some point, the text ends in the beginning of the first column of a new page. I would like to include my table on this page since it has a lot of free space below the text, but when I insert the table* right after the text, it goes to the top of the next page instead:    Do you know a way of obtaining the desired behavior?  Minimal working example :  \documentclass{article} \usepackage{lipsum}  \begin{document} \twocolumn  \paragraph{} \lipsum[1]  \begin{table*} \centering \begin{tabular}{|c|c|c|c|} \hline Column 1 & Column 2 & Column 3 & Column 4 \\ \hline Column 1 & Column 2 & Column 3 & Column 4 \\ \hline \end{tabular} \end{table*}%   \end{document}


Let $f: [a,b] \longrightarrow \mathbb{R}$ be an increasing function. If $x_1, \cdots, x_n \in [a,b]$ are distinct, show that $\sum_{i=1}^{i=n} o(f,x_i) < f(b) - f(a).$   I would like to know if my proof is correct and, if that's the case, an opinion if my proof writing is fine and an advice about how to write this better. Thanks in advance!  My attempt:     Let $P := \{ [t_{i-1},t_i] \ ; i = 1, \cdots, n, \ t_0 = a, t_n = b \ and \ x_i \in (t_{i-1},t_i) \ for \ each \ i \}$ a partition of $[a,b]$. The definition of oscillation of $f$ at $x$ given by Spivak is $o(f,x) := \lim_{\delta \rightarrow 0} [\sup f(B(x,\delta)) - \inf f(B(x,\delta))]$, then $[\lim \inf f((x_i - \delta, x_i + \delta)), \ \lim \sup f((x_i - \delta, x_i + \delta))] \subset [t_{i-1},t_i]$ when $\delta \rightarrow 0$ and $o(f,x_i) = \lim \sup f((x_i - \delta, x_i + \delta)) - \lim \inf f((x_i - \delta, x_i + \delta)) < f(t_i) - f(t_{i-1})$ for $i = 1, \cdots, n$. It's clear now that $\sum_{i=1}^{i=n} o(f,x_i) < \sum_{i=1}^{i=n} f(t_i) - f(t_{i-1}) = f(b) - f(a). \square$

Let $f$ be an increasing function defined on $[a,b]$ and let $x_1 < x_2 < \dotsb < x_n$ be $n$ points in the interior of $[a,b]$. Show that $\sum_{k = 1}^n [f(x_k^+) - f(x_k^-)]\leq f(b^-) - f(a^+)$.   The proof I have is very wordy and sketchy. I know it would be easier if I could find a telescoping sum but I've got a road block in my mind. :/


I'm a little bit confused by the notation "$K[t]$", what does it denote? I know that $K[X]$ is the polynomial ring over $K$, so the elements $P$ of $K[X]$ look like $P(X) = \sum_{n=0}^\infty k_n X^n$ with $k_n \in K$. Is $K[t]$ then just the image of the homomorphism $P \mapsto P(t)$ with $P \in K[X]$? Wouldn't that just be same as $K(t)$, which is the smallest field that contains both $K$ and $t$? What's the difference?

I have a question about notation specifically square brackets $[$ and round brackets $($.  My textbook doesn't explain any of this and I cannot find a reliable source online to confirm the difference.  So my question is: What is the difference between round brackets and square brackets in terms of notation in Field Theory? For example, I see $F(x)$ and $F[x]$ in my textbook and I've always assumed they were the same thing. But apparently they're not. Is there ever a time they're the same?  I wanted to know the difference, it may be a silly question but it's something I want to make sure I understand.


How about adding 's to the name of a company that ends in s for a possessive?  Is it the same guideline (go by how it would be pronounced)?  Thanks.

What is the possessive of a noun ending in ‑s?  Are these both right, or is the second one wrong?   the boys' books the boss' car


I have a DIV that I want to keep centered and docked to the bottom of the page.  I've pretty much achieved that except that it lists to the right.  I've setup a  to demonstrate the problem.  I suspect that I need to adjust margins but so far my attempts have been fruitless.  I tried adding:  margin: 0;   but nothing.  What am I missing?

Best way to center a <div> element on a page both vertically and horizontally?  I know that margin-left: auto; margin-right: auto; will center on the horizontal, but what is the best way to do it vertically, too?


I am using datatables to bind a DataSource to a GridView. This is how I do it.  I declared the dattable as follows.   private DataTable dt_CompanyNames;   Then  private void get_CompanyNames() {      dt_CompanyNames = new DataTable();      dt_CompanyNames = objDesignation_Bll.Get_CompanyNames();      gridCompanies.DataSource = dt_CompanyNames;      gridCompanies.DataBind(); }   So my question is What If I do those in below ways.  First I have to do this.  private DataTable dt_CompanyNames=new DataTable();   Then in my method I am using these statements.  1) Method 1   dt_CompanyNames.Clear();   2) Method 2   dt_CompanyNames.Rows.Clear();    3) Method 3   dt_CompanyNames.Reset();   4) Or should I stick with my exisiting method?  dt_CompanyNames = new DataTable();   In this method it always create new Datatable when each time this function calls. Is it good?  So what is the difference among those?  Is there one better than the other in terms of efficiency?

I recall there is a difference between some methods/properties called directly on the  class, and the identically named methods/properties on the  property. (Might have been the RowCount/Count property for which I read this.) The difference is one of them disregards , and the other respects/uses it.  In this particular case I'm wondering about the difference between  and . I can imagine one of them actually removes all rows, and the other one just marks them as deleted.  So my question is, is there a difference between the two Clear methods, and if so what is the difference?  (Oh, this is for .NET 1.1 btw, in case the semantics changed from one version to another.)


I have a situation where my root filesystem is supposed to have plenty of free space, but Debian behaves as if it had no free space left. Non-root users even refute to write anything complaining about the lack of free space. I.e. for example:  ~$ echo "qwertyu" > test -bash: echo: write error: Spazio esaurito sul device   (Sorry about the language, I didn't install the server myself. The error reads "ran out of free space on the device"). But root writes to the same directory without complaints. Also if I do df -h as root I get this:  /# df -h File system                                             Dim. Usati Dispon. Uso% Montato su rootfs                                                   48G   46G       0 100% / udev                                                     10M     0     10M   0% /dev tmpfs                                                   397M   88M    310M  23% /run /dev/disk/by-uuid/8063903c-80ad-4f72-81b0-cd67dbd48fc7   48G   46G       0 100% / tmpfs                                                   2,0G     0    2,0G   0% /dev/shm tmpfs                                                   2,0G     0    2,0G   0% /sys/fs/cgroup tmpfs                                                   5,0M     0    5,0M   0% /run/lock tmpfs                                                   100M     0    100M   0% /run/user /dev/sdb1                                                99G  9,6G     84G  11% /disk2   But du entries don't add up:  /# du -sh /* | sort -hr du: impossibile accedere a "/proc/12905/task/12905/fd/4": File o directory non esistente du: impossibile accedere a "/proc/12905/task/12905/fdinfo/4": File o directory non esistente du: impossibile accedere a "/proc/12905/fd/4": File o directory non esistente du: impossibile accedere a "/proc/12905/fdinfo/4": File o directory non esistente 9,4G    /disk2 3,8G    /var 3,2G    /data 1,6G    /usr 277M    /opt 130M    /root 129M    /lib 88M /run 45M /home 18M /boot 7,6M    /bin 6,0M    /sbin 5,2M    /etc 28K /tmp 16K /lost+found 8,0K    /media 4,0K    /srv 4,0K    /selinux 4,0K    /mnt 4,0K    /lib64 0   /vmlinuz 0   /sys 0   /proc 0   /initrd.img 0   /dev   (Error says "Cannot access yada yada: No such file or directory"). Be aware that /disk2 is a mount for an another partition.  Checking the filesystem didn't help either:  /# e2fsck -n /dev/sda1 e2fsck 1.42.5 (29-Jul-2012) Warning!  /dev/sda1 is mounted. Attenzione: essendo un controllo a sola lettura, il journal non verrà ripristinato. /dev/sda1: clean, 86568/3145728 files, 11666588/12563712 blocks   ("Being it a read-only check, the journal will not be recovered", but I guess the "clean" just below rules out this possibility).  Any idea what might be going on here? Consider the system runs on a VM somewhere and I can only access it via SSH.

I have a fileserver where df reports 94% of / full. But according to du, much less is used:  # df -h / Filesystem            Size  Used Avail Use% Mounted on /dev/sda3             270G  240G   17G  94% / # du -hxs / 124G    /   I read that open but deleted files could be responsible for it but a reboot did not fix this.  This is Linux, ext3.  regards


I want to display an interference pattern with  and \addplot3. The idea is to draw the surface I(x,y)=(1+V*cos(x)) and to show the influence of the visibility factor (V) on the pattern. For a bad visibility (V=0.15 for example) the contrast should be bad, but that's not what I obtain.    Here's the TikZ code:  \documentclass{article} \usepackage{pgfplots} \usetikzlibrary{calc} \begin{document} \begin{tikzpicture}[] \begin{axis}[ name=plot1, width=10cm,  height=3cm, xmin=-12, xmax=12, ymin=0,ymax=2.5, samples=50, axis lines=middle, inner axis line style={=>}, xlabel={$\phi$}, ylabel={$I/I_0$}, xlabel style={anchor=west}, ylabel style={anchor=south}, xtick=\empty, ytick={1,2}, ] \addplot[domain=-12:12]{1+.15*cos(deg(x))}; \end{axis} \begin{axis}[name=plot2,at={($(plot1.south)+(0,-2mm)$)},anchor=north,colormap/blackwhite,view={0}{90},width=10cm,height=2cm,xmin=-12, xmax=12,ymin=0, ymax=2,samples=50,hide axis] \addplot3[domain=-12:12, surf,shader=interp]{1+.15*cos(deg(x))}; \end{axis} \end{tikzpicture} \end{document}   Any idea?

I have two surface plots, which I would like to have to same color for the same height. So, as the first plot is dark blue for f(x,y)=0, the right plot should also be dark blue for f(x,y)=0. However, the color dark blue is assigned to the lowest point of the plot. Thus, the color for f(x,y) in the right plot is a bright orange.  Sample source:  \documentclass{report} \usepackage{pgfplots}  \begin{document}  % first plot \begin{tikzpicture} \begin{axis}[] \addplot3[surf,colormap name=hot,domain=-2:2] {exp(-x^2-y^2)}; \end{axis} \end{tikzpicture}  % second plot \begin{tikzpicture} \begin{axis}[] \addplot3[surf,colormap name=hot,domain=-2:2] {exp(-x^2-y^2)-exp(-(x-1)^2-(y-1)^2)}; \end{axis} \end{tikzpicture}  \end{document}     How can I force the plots to have the same color for the same height?


We installed on grid solar plant. Before installation P. F. was always maintained to 0.99 by capacitor banks(APFC panel). But after solar connection is varies and goes down up to 0.16. APFC panel CT position is on grid only. Should it be after combination of solar and grid?

We installed solar plant in factory. After that power factor goes down to 0.16. Normally it never goes below 0.85 in history even if we keep APFC off. We always maintained it to 0.99. Note - Main meter is uni directional and not bidirectional.


My daughter is traveling from SA to Ireland Dublin via Heathrow .  She will be catching a connecting flight to Dublin via an Irish airline  What visa is required ?

Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.


I am a developer using Linux fedora.I seen in lot of links that it is not a good idea to use root user,because someone can easily hack my password.Instead create a separate account for development purpose.But i am using my own fedora machine and myself only using.In this case is it recommend to use a separate account instead of "root".Need more clarification

I've often come across posts on forums or other websites where you see people joking in such a manner about running/logging in as root as if it's something awful and everyone ought to know about it. However, there isn't much that a search reveals on the matter. It maybe widely known to Linux experts, but I really don't know why. I remember always running as root when I first tried Linux years ago (Redhat and Mandrake) and don't remember running into any problems because of that. There are actually some distros that have a bright red background with alert signs all over it as wallpaper for the root user (Suse?). I still use the "Administrator" account for regular use on my Windows installation and haven't ever run into any problems either.


#include <iostream> using namesapce std; class A {   public:          virtual ~A(){cout<<"delete A"<<endl}; }; class B: public A {   public:          B(int n):n(n){}          void show(){cout<<n<<endl;}          ~B(){cout<<"delete B"<<endl;}   private:          int n;  } int main() {    A *pa;    B *pb = new B(1);    pa = pb;    delete pa;    pb->show();    return 0; }   when destructor of calss A is virtual ~A(){...},the output of program:     delete B   delete A   1  when destructor of class A is ~A(){...}, the output of progarm:     delete A    0  why the value of n is different, when destructor of class A is virtual or non virtual?  when call destructor of B to destroy object, why the calss member n is still existent?

I have a solid understanding of most OOP theory but the one thing that confuses me a lot is virtual destructors. I thought that the destructor always gets called no matter what and for every object in the chain. When are you meant to make them virtual and why?


A minimal example of my code is shown. The problem is, first of all, that the space between the title of the example and the description of the problem is too large. So I want to reduce the space, but I cannot figure out how. Secondly, if the example is too long it should continue on the next page, but the command allowframebreaks does not do the job.        \documentclass[10pt, ]{beamer}  \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage[T1]{fontenc}  \usepackage[framemethod=TikZ]{mdframed}  % Example enviroment \newcounter{exm}[section]\setcounter{exm}{0} \renewcommand{\theexm}{\arabic{section}.\arabic{exm}} \newenvironment{exm}[3][]{% \refstepcounter{exm}% \ifstrempty{#1}% {\mdfsetup{% frametitle={% \tikz[baseline=(current bounding box.east),outer sep=0pt] \node[anchor=east,rectangle,fill=white!100] {\strut \small{Eksempel~\theexm: #2}};}} }% {\mdfsetup{% frametitle={% %\tikz[baseline=(current bounding box.east),outer sep=0pt] %\node[anchor=east,rectangle,fill=white!100] {\strut \small{Eksempel~\theexm:~#1: #2}};}}% }% \mdfsetup{innertopmargin=0pt,linecolor=green!80,% skipabove=7pt, skipbelow=0pt, rightline=false, leftline=true, topline=false, bottomline=false, linecolor=green, innerleftmargin=5pt, innerrightmargin=5pt, innertopmargin=0pt, leftmargin=0cm, rightmargin=0cm, linewidth=3pt, innerbottommargin=0pt,% frametitleaboveskip=\dimexpr-\ht\strutbox\relax } \begin{mdframed}[]\relax% \label{exm:#3}}{\end{mdframed}}  \newcommand{\exam}[4]{% \begin{exm}{#1}{#2} \begin{small} \begin{textit} #3   \end{textit} \\[0.2cm] \textbf{Solution:} \\ #4 \end{small} \end{exm} }  \begin{document}  \section{Section Title} \begin{frame}[allowframebreaks]{Frametitle} \exam{Title of the example}{LabelName}{Descibtion of the problem...}{A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.A very long text. A very long text. A very long text. A very long text. A very long text. A very long text.} \end{frame}   \end{document}

The mdframed environment fails to break into several pages (slides) when used in a frame environment from the beamer class.  In the other hand, the boitecoloriee environment from the boites package can be broken into several pages.  Here is a document that demonstrates the issue. It should not be compiled directly into pdf because boitecoloriee uses pstricks.  \documentclass{beamer} \usepackage{xcolor,boites,boites_exemples,pstricks} \usepackage{mdframed} \usepackage{lipsum}  \begin{document}  \begin{frame}[allowframebreaks]{Using \texttt{boitecoloriee}}   \begin{boitecoloriee}     \lipsum[1-2]   \end{boitecoloriee} \end{frame}  \begin{frame}[allowframebreaks]{Using \texttt{mdframed}}   \begin{mdframed}     \lipsum[1-2]   \end{mdframed} \end{frame}  \end{document}   Maybe is there a way to fix mdframed to work in slides too. Any clues?


If I draw at random from a set of 50 numbers( say 1:50), five numbers without replacing the drawn number, and then repeat this process ten times starting each 'draw' from the full set, how likely is it that I will draw every number of the set? How do I calculate this? Would it be 50( the number of 'draws') divided by 500 ( the total number from which the draws were taken) i.e.10% or is it more complicated than this?

I'm playing the , which is an Internet adaption of the classic Panini albums that are usually published for the soccer world cup, European championship, and possibly other tournaments.  The album has placeholders for 424 different stickers. The purpose of the game is to collect all 424. The stickers come in packs of 5, which can be obtained through codes found online (or, in case of the classic printed album, bought at your local newsstand).  I make the following assumptions:   All stickers are published in the same quantity.  One pack of stickers does not contain duplicates.     How can I find out how many packs of stickers I need to acquire in order to be reasonably sure (let's say 90%) that I have all 424 unique stickers?


Let $p$ be a prime number. Find all positive integers $x$ and $y$ for which $$\dfrac{1}{x} + \dfrac{1}{y} = \dfrac{1}{p}.$$  Multiplying the given expression by $xy$ results in $y+x = \dfrac{xy}{p} \Rightarrow p(x+y) = xy$. I was suggested to get this to the form $(x-p)(y-p) = p^2$, which seems a bit weird to me since I usually with these kinds of questions I would find a system which would lead to finding the correct $(x, y)$, but having the term $p^2$ is not something I've seen before. Is the idea behind this so that I would want to have an expression where I have something of the form $(x-k)(y-n) = p$ and could deduce from here that either $(x-k) = 1$, $(y-n) = p$ or the other way around since $p$ can only have the factors $1$ and $p$?

Write down the set of distinct solutions and prove your list is complete. $x$ and $y$ are positive integers.  I have rewritten it as $\frac{(x+y)}{xy} = \frac1p$, but I don't understand where to go from here?


Let $x,y \in \mathbb{C}$ and  $d(x,y)=\frac{2|{x-y}|}{\sqrt{1+|{x}|^2}+\sqrt{1+|y|^2}}$  I am unable to show the triangle inequality for this metric.

Show that $(X,d)$ is a metric space where $X =\Bbb C $ and the distance function is defined as:   $$d(x,y) = \frac {2|x-y|}{\sqrt {1+|x|^2} +  \sqrt {1 + |y|^2}}, \text{ for } x,y \in \Bbb C.$$   I have done the proof of the first two propositions for being a metric, but I'm having a problem in proving the triangle inequality.


I am comfortable when I am asked to calculate the range of a rational function, but how do we do the reverse? I came across this problem.  If $$f(x)= \frac{x^2 + x + c}{x^2 + 2x + c}$$ then find the value of $c$ for which the range of $f(x)$ does not contain $[-1, -\frac{1}{3}]$.

If the range of the function $f(x)= \dfrac{x^2+x+c}{x^2+2x+c}, x\in \mathbb R$ is $\left[\dfrac 56, \dfrac 32\right]$ then $c$ is equal to?    Attempt:   $y=  \dfrac{x^2+x+c}{x^2+2x+c}$  For real values of $x$, $\Delta \ge 0$  $\implies 4y^2(1-4c) +1-4y(1-2c) - 4c \ge 0$  What do I do next? I am really unable to understand the concept to be followed after this. Could someone explain that?   The answer is:       $c= 4$