A bard who takes the Magic Initiate feat and chooses the bard spell list for the feat can use spell slots to cast the 1st-level spell they learn from the feat. A wizard who takes the feat and chooses the wizard list can do the same. Can an Arcane Trickster rogue or Eldritch Knight fighter who takes the Magic Initiate feat and picks the wizard spell list also use their spell slots to cast the 1st-level spell they pick for the feat? Both the AT rogue and the EK fighter use the wizard spell list for their Spellcasting feature, so one could assume that they could use their spell slots to cast a wizard spell from the feat... But is that assumption correct?  This Q&A addresses the general case:  However, the Arcane Trickster rogue and Eldritch Knight fighter are a bit of an exception and aren't specifically addressed by that Q&A. Both the Arcane Trickster rogue and Eldritch Knight fighter use the wizard spell list, even though they are not themselves wizards. As a result, I'm not 100% sure if my assumption about their interaction with the feat is correct.

Can you cast a spell learned from the Magic Initiate feat using spell slots? Say I play a wizard who learns cure wounds by taking the Magic Initiate feat. Could I cast that spell using the Wizard's spell slots?


I have to classfier a medical images, but these images are big(3000x2900),, i need way to resize. and then training it. Can i training these images without resize???

Is there an obvious way to do this that I'm missing?  I'm just trying to make thumbnails.


I am stuck currently on this question while learning Linux. Can anyone help me?

I often see things like     read man xyz   For more information read xyz's man page.   see info xyz    so I wonder:   How can I get help on terminal commands generally? What exactly are these man and info pages?   How can I find and view them?


I was trying to create the same as in this tutorial:    But when I do exact the same my objects keep regrowing. So each next object will be even bigger then the one before.  Can someone please tell me what I did wrong here?

We know that the there is an Object Offset option for Array modifier, but when trying to make a circular array with that offset object as the center of the array circle, it always doesn't behave quite like what's expected. So how to make a nice and controllable circular array?  P.S.: There is an old  about moving the object's origin. I wonder if there is any way to do this without changing the location of the origin. :)


I have received a refusal for a UK visit visa. Below is the relevant text of the refusal. What does this mean and what steps can I take to significantly increase my chances of success in a potential new attempt to apply?      The Decision      I have refused your application for a visit visa because I am not satisfied that you met the requirements of paragraph(s) V4.2-V4.10 of the Appendix V: Immigration Rules for Visitors because:      Home Office records shows that you have been previously been refused a UK visa (VAF Shefo/344051). However each application has to be assessed on it own merits using the information and evidence submitted.      You state that you wish to visit the United Kingdom to attend your interview with the British Army and you have provided a reference letter in support of this. You state that your sister will fund your trip and you have provided her bank statements. However, the onus is on you to qualify for a visit visa based on your own circumstances and your own intentions.      In order to be able to  make a decision on whether or not to grant you a visit visa in this category, I have taken into account your stated circumstances in Ghana, the reason for your visit and your proposed travel arrangements. I note that you state you earn GHS 266.00 (48.44) pounds per month employed as a sales representative. You appear to have no property, investment,savings or asset in your own country. I must take into account your personal and economic circumstances in Ghana when coming to my decision and given that you would not be able to afford to fund this visit without third-party financial assistance, I am not satisfied that your personal circumstances in Ghana are such that you would have sufficient intention to leave the United Kingdom at the end of your visit as stated.       Given the statement you have made and the documentary evidence you have presented to support your application I am not satisfied that your circumstances in Ghana, coupled with your reasons for wishing to travel to the UK, are such that you have shown your intention are as stated or that you intend to leave the UK at the end of your proposed visit.      In light of all the above , I am not satisfied that you are a genuine visitor and will leave the UK at the end of your visit. Your application for visit visa has been refused under paragraph V4.2(a).

The UK Visas and Immigration Directorate publishes  that provides helpful tips that can result in successful visa applications. Section 2 of this guidance opens is entitled "other documents you may want to provide" (emphasis mine).  Section 2: other documents you may want to provide – all visitors This section provides guidance on the types of documents that you may want to provide to help us consider your application against the Immigration Rules. Previous travel documents/passports, which show previous travel. Financial documents showing that you have sufficient funds available.  These must clearly show that you have access to the funds, such as:  bank statements building society book proof of earnings such as a letter from employer confirming employment details (start date of employment, salary, role, company contact details) where a third party (who is either in the UK or will be legally in the UK at the time of your visit) is providing financial support to you e.g. a business, a friend or a relative, documents to show that they have sufficient resources to support you in addition to themselves and any dependant family should be provided   The first item is "bank statements" and this ties in with the , which says...  evidence that you can support yourself during your trip, eg bank statements or payslips from the last 6 months  (Note 'eg' is a Latin abbreviation meaning "for example"; this appears to be optional rather than a fixed requirement.) Question: How should someone interpret this such that the chances of success are maximized? How many statements should I submit? What are they looking for and what do my bank statements tell about me?


I need to put a quote in my research paper. My friends give me different answers so I'm confused now...  Would it be      According to "Title", "blah blah blah."   or     According to "Title," "blah blah blah."

I have been/am being taught that end punctuation should always go inside quotes. For example, you are supposed to write:     Marvin thought it was "awful."   The problem is I do not see how does this make sense. Intuitively, I always wrote:     Marvin thought it was "awful".   as that makes more logical sense — you want a quote to be an exact replication of what somebody else said, so why should you add punctuation inside?  I always thought it made more sense to not touch the quote and add anything after or before if it must be added.  So, why should I put end punctuation inside quotes?


I have this problem I know I need to approximate the value with taylor polynomial and its error formula is $$|R_n(x)|\leq \frac{1}{(n+1)!}|x-a|^{n+1}$$ but i couldnt figured it out i should calculate up to which degree. Should I use radians? Can anyone help me about that

I need to calculate $\cos(\pi/20)$ with an error less than $10^{−5}$ of Taylor/Maclaurin series, What I did is like that:  $$|R_n(X)|=\left|\frac{(-1)^nC}{(n+1)!}\right|=\left|\frac{C}{(n+1)!}\right|_{0<C<\frac{\pi}{20}}<\frac{\frac{\pi}{20}}{(n+1)!}=\frac{\pi}{20(n+1)!}<10^{-5}$$  The statement is true when n=7, is my answer correct?


I tried extruding the edges along their normals but it would not follow the angle properly, so i was wondering if there was a way to extrude the face and as i pull it out, it will scale it to keep the edges co planar to their origin edges and corresponding face.

I am trying to extrude faces of a cylinder along local normals. 3dsmax can do it easy, couldn't find how to do it in blender.  The extrude region option extrudes it as shown in the first example. I want it done like the 2nd example.


I can't find my iphone 6 using find my phone and I am not sure if the battery has died or someone turned it off.  Is there any way to find out the last location of my iphone before the battery died or the phone was turned off?

My phone was stolen last night. I made sure it was in Lost Mode in iCloud and it was immediately in Offline status when I open iCloud. I am positive the thief switched it off. Now I am 100% certain the Find my iPhone option was turned on on my iPhone, but will the "Lost Mode" be of any help if it was not turned on on the iPhone? Would it be showing "Offline" if I did not turn on the option?


I there a way to pad String result in SQL server?   Select str from table_name where...   I want str to return with length of 13 with leading '0'.  For example:   if str = '12345678910' my where will return 13 positions: '0012345678910' str = '12345' -> '000000012345'   In addition, after padding the result i need to query str 3,4 position.  Is there a way to do all of this in one query?

Let's say I have an int with the value of 1. How can I convert that int to a zero padded string, such as 00000001?


Suppose that k(·, ·) and k 0 (·, ·) are kernels. Prove that l(·, ·) where l(x, y) = k(x, y) + k0 (x, y) is also a kernel.  I am having trouble proving this, can you help?

I am reading the Pattern Recognition and Machine Learning book by Bishops. I have some difficulties proving the (6.21) equation. Can someone help me?   N.B: If someone has a better title for this question, i'm opened to it as i couldn't find the good words.


I heard some sentences with this form from English speakers: "what I do know is that..." or  " We do share the same..." The question is: what is the applicant of do in these sentences? Why they use it before main verbs?

What is the difference between I play and I do play?  For example:  If someone were to ask to me, do you play soccer?


I've created a class that's designed to rotate a vector. (I realize this functionality basically already exists in STL, I'm just trying get a handle on template classes.)  My specification file:  template <class T> class ShiftVec { private:     vector<T> vec;  public:     ShiftVec(vector<T>);     vector<T> getVec();     void shiftRight(int);     void shiftLeft(int); };   My implementation file:  template <class T> ShiftVec<T>::ShiftVec(vector<T> v) {     vec = v; }  template <class T> vector<T> ShiftVec<T>::getVec() {     return vec; }  template <class T> void ShiftVec<T>::shiftRight(int n) {     rotate(vec.begin(),            vec.end()-n, // this will be the new first element  template class ShiftVec<int>; template class ShiftVec<double>; template class ShiftVec<bool>; template class ShiftVec<string>;   When I run this, I get a bunch of errors that look like this:  Undefined symbols for architecture x86_64:   "ShiftVec<int>::shiftRight(int)", referenced from:       _main in main.o   "ShiftVec<int>::getVec()", referenced from:       _main in main.o   "ShiftVec<int>::ShiftVec(std::__1::vector<int, std::__1::allocator<int> >)", referenced from:       _main in main.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)   I'm not sure exactly what's going wrong here. A push in the right direction would be helpful.

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I can see an answer where it suggests a 3-wire run from the fixture but I'm hoping to use existing wiring and it only has black and white wires coming from the bathroom fan to the old timer switch.   The new modern timer switch has red, white and black wires out (and green of course).  Which wires connect to which wires please?  and thanks Scott

I'm trying install  but the instructions do not match reality. The instructions refer to the existence of a black (load) cable and a white (neutral) cable supposedly coming out of the wall, but instead I have two black cables and a naked wire. Is the naked wire the equivalent of the white in the diagram?


I'm currently taking a course where I acquired the textbook as an e-book. Physical copies were available too, but I find kindle-versions far more convenient as I can read it wherever, whenever, using the kindle app on my phone.  Then naturally during lectures, I'll have my phone out (on mute of course) so that I can access the book. This is no different to any other student in the hall who have their physical copy out. In fact, I am less disturbing, because when those other students need to look something up, you'll hear pages turning, while my finger is silently scrolling my phone.  And yet, my professor doesn't seem to realize the benefits of technology and bans usage of phones. I of course do not intend to follow this policy: I've paid money for my e-book and am not going to spend more money for another physical copy just to appease this tosser.  However, my question is specifically, what should I do? Should I just keep on using my phone as usual, or should I contact some authority figure immediately? I'm not really worried about what he can do (because there's not really anything he CAN do, he can't throw me out of class or anything), but I would still like to take optimal steps.

Inspired by another question where a user asks how to handle students with a phone, my question is from the opposite perspective: what is the correct response when a lecturer asks one to put away the phone?   This actually recently happened to me (a few months ago), and for obvious reasons (not wanting to interrupt the flow of the lecture, not wanting to have a falling out with the professor, etc), I just put my phone down.   But to be honest, I don't think that's the correct response, or at least I feel this is not the way it should be, because I find such demands inappropriate for a number of reasons, and so I shouldn't be giving in to them, should I?    My reasoning:  First of all, and this may sound immature, but what I do with my phone is none of the lecturer's business. As long as I am not disturbing anybody (audio is always off, I am never typing loudly because it's a touch-screen, and nobody is distracted by the screen because I make sure to sit in the back), it shouldn't be a problem.   Secondly, I find that such demands can impede my learning. I often use the phone to look up information related to what the lecturer is actually talking about. If a topic is mentioned that I don't quite recall, a quick google search or a 10-second glance at the topic's Wikipedia page brings me up to speed. Or perhaps the textbook for the course is on my cloud server and I need to the phone to actually access the book, if I didn't bring (or even buy) the physical copy.   Finally, I find it highly disrespectful to call a student out for being on a phone in the middle of a lecture in front of all others. Such conversations, if they need to be had, should be had in private. Approach me after the lecture or during the break if you have a problem. Don't call me out in front of the entire class.


I am a rookie programmer in Java. I want "aaa" to be printed in main and displayed "123". In C++ if use pointer in the define arguement (e.g. char * a), and will return the value to the variable which is passed to the function.  How do I make this happen in Java? and I don't want to have a return type of String. (I need to use the argument to print). It shows null" for now.. If anyone could help I will appreciate!   public class DeppDemo {     private String aaa;      public void abc(String a) {         a = "123";     }      public static void main(String[] args) {         DeppDemo demo = new DeppDemo();         demo.abc(demo.aaa);         System.out.println(demo.aaa);     } }

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 a web site that provides daily real estate updates. Users register, and we send them an email every day. However, Gmail is marking all of our emails as spam. What should we be looking out for?

This is a tricky one and I've always relied on techniques, such as permission-based emails (i.e. only sending to people you have permission to send to) and not using blatantly spamish terminology.  Of late, some of the emails I send out programmatically have started being shuffled into people's spam folder automatically and I'm wondering what I can do about it.  This is despite the fact that these particular emails are not ones that humans would mark as spam, specifically, they are emails that contain license keys that people have paid good money for, so I don't think they're going to consider them spam  I figure this is a big topic in which I am essentially an ignorant simpleton.


When I read a source code C#, I see a line   return new Form(ElementType.Checkbox, ((IHTMLInputElement)htmlElement).@checked);     But I can NOT find it with keyword .@checked. Could you please tell me what is .@checked called and its meaning?    Update answer Firstly, Thanks @Yeldar Kurmangaliyev, @Erik Funkenbusch and @TcKs. Secondly, I'm sorry for making duplicate post. Because I searched with ".@checked" and saw nothing. Finally, I understood that @ sign help define a variable whose name is as same as C# keyword, like this:    string @string = "This is a string"; string str = @string; // str = "This is a string"

I discovered that you can start your variable name with a '@' character in C#.  In my C# project I was using a web service (I added a web reference to my project) that was written in Java. One of the interface objects defined in the WSDL had a member variable with the name "params". Obviously this is a reserved word in C# so you can't have a class with a member variable with the name "params". The proxy object that was generated contained a property that looked like this:  public ArrayList @params {     get { return this.paramsField; }     set { this.paramsField = value; } }   I searched through the VS 2008 c# documentation but couldn't find anything about it. Also searching Google didn't give me any useful answers. So what is the exact meaning or use of the '@' character in a variable/property name?


An eye-glazingly, mind-numbingly boring debate is raging on usmessageboard.com over hyphenation. One user posted     full-throttle, out-of-the-gate, naked attempt by the press   to which another user responded     Has any other POTUS " out-of-the-gate" [sic] preceded and commenced their presidency   which the first user took as an attack on his grammar, and, well, the to-hyphenate-or-not-to-hyphenate debate has raged ever since.   In an attempt to restore the tranquility of the board and its usual civil tone, I offered to submit an appeal for arbitration here.   The question mentioned of which mine may be a duplicate does indeed answer many of the points raised in the battle raging elsewhere, but doesn't address others, which I will try to list below. Nor does it cover the [sic] aspect of our controversy. I realize the question could be split into two separate questions, but that would reduce the chance our community would receive the fairest possible judgment from our community.   And that brings up the objection below to the appeal for arbitration. I imagine there are any number of reasons someone might post a question here. Some, I suppose, are composing an email at work their boss will see, and they want to be as precise as possible so that they make a good impression. Others may be working on a thesis they are going to present and want to be sure of their lingual footing during the orals. Another might be composing a letter to a cheating lover and she wants to express her broken heart in a crystal clear voice free of any quaver an ungrammatical sentence would give it. We neither ask them the reason, nor sanction them if they offer the reason.   I offered the reason because I thought it was a light-hearted and inoffensive addition to my question without detracting from it.   The aspects of this question that weren't addressed in the other's answer, thorough as it was:   Since hyphenation is to be used to form a compound word immediately preceding a noun, out-of-the-gate should not have been hyphenated because of the interposition of the word "naked" between the adjectival phrase and the modified noun, "attempt". The OP responded that the stack of adjectives all qualified as immediately preceding the noun; The temporal quality of "out of the gate" made it adverbial and thus undeserving of a hyphen. In response, the OP maintained "out-of-the-gate" was indeed adjectival; The [sic] was not a criticism of the OP's grammar, but a defense against the possibility the OP's mistake would be imputed to the respondent.   So there you have it. Was this a mistake?     full-throttle, out-of-the-gate, naked attempt by the press

Someone has asked for answer to these topics. However, I still want someone to provide me with simple and universal answers. I recently read a sentence from the English-speaking person. It is in an article. It is, ' The available options for mitigating pad cratering are not universally effective (see link below), but they may be helpful on a case by case basis until more crack resistant laminates are developed and become available.  '  If I am to write this, I will use 'a case-by-case basis until more crack-resistant laminates'   Can anyone tell me when to use a hyphen to coin a new word?


Find $$\lim_{n\to\infty} \sum_{k=1}^{n}\left( \frac{k}{n}\right)^{n}$$  I can't compare it with similar series and I can't change it to Riemann's sum.

I'm asked to find $\displaystyle\lim_{n\to \infty}\sum_{k=1}^n \left(\frac{k}{n}\right)^n$.  It seems that the sum converges.  I managed to prove that $\forall n,1<\sum_{k=1}^n \left(\frac{k}{n}\right)^n<e$  But I don't know how to prove convergence, nor find the value of the limit.


please could someone give me a relatively straight forward answer why the gravitational field strength follows a straight line (linear) relationship with distance from the center of the Earth but when you get to the surface it follows a 1/r^2 relationship?

If you could travel to the center of the Earth (or any planet), would you be weightless there?


Find the inverse Fourier transform of $\widehat{f}(\xi) = \frac{1}{1+\xi^2}$. I wanted to use the inverse Fourier formula to solve the problem. $$ f(x) =  \frac{1}{2 \pi} \int_{-\infty}^{\infty} e^{ix\xi} \frac{1}{1+\xi^2} d\xi $$ Integration by part is not helpful at the first stage, and I am not sure about differentiating both side w.r.t $x$ and then taking the derivative inside and then using integration by parts. (I have issue with taking the derivative as well, in the sense how do we know that function is differentiable and even ignoring that issue, I am not able to find a closed form).

I need help to calculate the  Fourier transform of this funcion  $$b(x) =\frac{1}{x^2 +a^2}\,,\qquad a > 0$$ Thanks.


If $ G $ has no non-trivial automorphism, then $ G $ is abelian and $ g^2 = e $ for all $ g \in G $ .  With the assumption, I dont know how to start the proof.  If there is no non-trivial automorphism, then there is only trivial automorpism, the identity morphism. But how can I show  $ g^2 = e $ for all $ g \in G $ with it?

Well, this is an exercise problem from Herstein which sounds difficult:   How does one prove that if $|G|>2$, then $G$ has non-trivial automorphism?   The only thing I know which connects a group with its automorphism is the theorem, $$G/Z(G) \cong \mathcal{I}(G)$$ where $\mathcal{I}(G)$ denotes the Inner- Automorphism group of $G$. So for a group with $Z(G)=(e)$, we can conclude that it has a non-trivial automorphism, but what about groups with center?


I have an If statement in Java but it doesn't funtion correctly. I put a condition but the if doesn't respect that.  My code :  btnNewButton.addActionListener(new ActionListener() {         public void actionPerformed(ActionEvent e) {             String name="";             String surname="";             name = txtName.getText().toString();             surname = txtSurname.getText().toString();             if (name!="" && surname!="") {                 msgAlarm.setText("<html>Insert all data<br/>before continuing!<html>");                  Runnable runnable =                          (Runnable) Toolkit.getDefaultToolkit().getDesktopProperty("win.sound.exclamation");                  runnable.run();             }else {             System.out.println("Else Started");             }   However when I run the program and the txtName and txtSurname are empty, Java run first statement. How can I resolve? Many Thanks.

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?


Under the "Close" dialog as well as the explanation below a closed question:     Questions on Stack Overflow are expected to relate to programming or   software development within the scope defined in the FAQ. Consider   editing the question or leaving comments for improvement if you   believe the question can be reworded to fit within the scope. Read   more about closed questions here.   I understand that the links forward to the appropriate help center page, but it's still incorrect.

Close reasons still have links to the FAQ in them - these should be referred to as the Help Center, since that's what it is now.   Not Constructive (emphasis obviously mine)     We expect answers to be supported by facts, references, or specific expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, see the FAQ for guidance.  Off Topic (ditto)     Questions on Stack Overflow are expected to relate to programming or software development within the scope defined in the FAQ. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope.  Too Localized (...)     This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, see the FAQ.  Not A Real Question (...)     It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, see the FAQ.    All of these should be changed to "see this Help Center topic" (or similar). Since, y'know, it's the Help Center, now, not the FAQ.


I have a fun little  deck. From Gatherer     Whenever Shocker deals damage to a player, that player discards all the cards in his or her hand, then draws that many cards.   Note that the errata does not specify combat damage. When the stars align I usually have the following auras on the Shocker.      : Enchanted creature gets +2/+2 and has "Tap: This creature deals 1 damage to target creature or player." : Whenever enchanted creature deals damage to a player, return target creature that player controls to its owner's hand.     My understanding is that when I damage a player (I even targeted myself to get a new hand in desperation) that his hand is discarded and new cards are drawn. Then at the same time a creature (assuming there is a legal target) returns to his hand. Netting the player 1 extra card in his hand once the action is completed.   Is this correct? Are there rules addressing this scenario?

I had several humans on the battlefield.  On turn three, I played . On turn four, I played . On turn five, during my upkeep, this question came up.  At this point, I need to draw/reveal three cards. If I reveal a human, Descendants' Path will allow me to cast it without paying its mana cost.  So, does it matter when I draw the human?  The static abilities state "at the beginning up your upkeep..." which leads me to believe that those two draws/reveals would happen before my normal draw. If that's the case, does the draw order happen in the same order that I played the enchantments?  In the end, that's how we decided to do it. I drew first for Triumph of Ferocity, then I revealed for Descendants' Path, then I drew for my turn. Did we do it right?


What was John Napier's motivation to introduce the logarithmic function?  It neither makes the calculations easier nor accurate (at least for me). How could people think of its importance even before Calculus came into play and showed its connection with the exponential function or, area under the graph $\dfrac{1}{x}$ ?

In the wikipedia article on logarithms, I am clueless about the approach and motivation for the following computations done by Napier (and the mysterious appearance of Euler's number) in this . Please help me understand:       By repeated subtractions Napier   calculated $10^7(1 − 10^{−7})^L$ for L   ranging from 1 to 100. The result for   $L=100$ is approximately $0.99999 = 1  − 10^{-5}$. Napier then calculated the   products of these numbers with $10^7(1  − 10^{−5})^L$ for L from 1 to 50, and   did similarly with $0.9995 ≈ (1 −  10^{−5})^{20}$ and $0.99 ≈ 0.995^{20}$.   These computations, which occupied 20   years, allowed him to give, for any   number ''N'' from 5 to 10 million, the   number ''L'' that solves the equation      $$N=10^7 {(1-10^{-7})}^L$$      In modern notation, the relation to   natural logarithms is:      $$L = \log_{(1-10^{-7})} \!\left(  \frac{N}{10^7} \right) \approx 10^7  \log_{ \frac{1}{e}} \!\left(  \frac{N}{10^7} \right) = -10^7 \log_e  \!\left( \frac{N}{10^7} \right)$$      where the very close approximation   corresponds to the observation that      $${(1-10^{-7})}^{10^7} \approx  \frac{1}{e}. $$   I understand the computations, but I don't know what's going on.


Let $f:\mathbb{R}\to \mathbb{R}$ be a continuous function such that $\forall x \in R$ and $ t \geq 0$, $f(x)=f(xe^t)$. Then prove that $f$ is a constant function.  This is what I did: For a typical $t =t_0$ we have: $$f(x)=f(xe^{t_0}) \to (1)$$ Now plugging $x=1$ above we get: $$f(1)=f(e^{t_0}) \to (2)$$ Also plugging in $x=e^{-t_0}$ in $(1)$ we get: $$f(e^{-t_0})=f(1)\to (3)$$ So from $(2),(3)$ we have: $$f(e^{-t_0})=f(e^{t_0}) \to (4)$$ Similarly we get: $$f(-e^{-t_0})=f(-e^{t_0})\to (5)$$ from $(4),(5)$ we get: $$f(x)=f\left(\frac{1}{x}\right), \forall x \in R-\{0\}$$ Any way to proceed from here?

This question was asked in :     Let $f: \mathbb{R} \to \mathbb{R}$ be a continuous function such that   for all $x\in\mathbb{R}$ and $t\ge 0$, $$f(x)=f(e^{t}x)$$ Show that   $f$ is a constant function.     My attempt:  Suppose that $f$ is not a constant function. Then $f(0)\ne f(x_0)$ for some $x_0 \in \mathbb{R}$. We eliminate the possibilities that $x_0>0$ and $x_0<0$, thus proving that our assumption was wrong.  Case 1: ($x_0>0$). Let $k$ be any real number between $f(0)$ and $f(x_0)$ (not inclusive). Then by the intermediate value theorem,  there exists $y_0 \in (0, x_0)$ such that $f(y_0)=k$. But $f(y_0)=f\left( e^{\ln \left( \frac{x_0}{y_0}\right)  } y_0\right) = f(x_0)$ which contradicts our assumption that $f(y_0)$ was between  $f(0)$ and $f(x_0)$.  Case 2: ($x_0<0$). Let $k$ be any real number between $f(0)$ and $f(x_0)$ (not inclusive). Then by the intermediate value theorem,  there exists $y_0 \in (x_0, 0)$ such that $f(y_0)=k$. But $f(x_0)=f\left( e^{\ln \left( \frac{y_0}{x_0}\right)  } x_0\right) = f(y_0)$, a contradiction again.    Is this proof correct? I was probably looking for a direct proof if there's any. Alternative proofs are welcome.


I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I just finished a website that I designed and submitted it to  for performance reviews, and this is the results I got:    It says I need to set expiry date or a maximum age in the the HTTP headers, but I don't know how it is possible to set the expiry date for anything other than cookies/sessions, so I have no clue what this means or how to do it.

I have recently analysed my website with pagespeed addon on firebug. It suggested me to set expiration on CSS, JS and image files.  I am wondering how do i do this?


Let $$S_n=e^{-n}\sum_{k=0}^n\frac{n^k}{k!}$$  Is the sequences$\{S_n\}$ convergent?  The following is my answer,but this is not correct. please give some hints.  For all $x\in\mathbb{R}$, $$\lim_{n\rightarrow\infty}\sum_{k=0}^n\frac{x^k}{k!}=e^x.$$ then   $$\lim_{n\rightarrow\infty}e^{-n}\sum_{k=0}^n\frac{n^k}{k!}=1.$$

I'm supposed to calculate: $$\lim_{n\to\infty} e^{-n} \sum_{k=0}^{n} \frac{n^k}{k!}$$ By using WolframAlpha, I might guess that the limit is $\frac{1}{2}$, which is a pretty interesting and nice result. I wonder in which ways we may approach it.


I want to know how to prove that there exists a group of base . these base make the matrix of this map is a matrix whose Principal diagonal element is all zero.

Prove that if $A$ is a square matrix and $\mathrm{Tr}(A)=0$, then there exists an invertible matrix $R$ such that the matrix $T=R^{-1}AR$ has all entries on its main diagonal equal to $0$.   It seems like the formula $A=S\Lambda S^{-1}$, but maybe it does not help.  Thanks so much.


I was using image references to create a character however after pressing some keys on my keyboard, which activated a short cut, when i attempted to go into front view to see my reference u=image, it appeared to have disappeared. As i was following a tutorial and therefore was doing it as a learning exercise i was willing to restart the project again, i started a new file. However once i re entered the reference images it still would not appear on my front view (I did set the axis' correctly)  If anyone knows of anything that could help that would be most appreciated,  Thank you, Nura

How do I put a backdrop behind the model that I am creating so that I can compare the picture to the model while editing?


Up to isomorphism, I would like to say that there are only two groups of order $21$. There is the cyclic one, and using Sylow's theorems it is easy to see that there could be at most two nonabelian ones. Is there a way to show that there is in fact only one (up to isomorphism) without having to write down all the elements and the corresponding tables (I only see that for now)?

Let $G$ be  a group of order  $21$. Find the number of non-isomorphic groups of order $21$  My solution: If  the group $G$ is commutative,then $G$ can be expressed as a direct product of cyclic groups of prime power order,i.e it is either $\mathbb  Z_3\times \mathbb Z_7$ or $\mathbb Z_{21}$ which is same  My problem is when $G$ is commutative.How to proceed here?


Suppose I have some slightly messy data with an r squared of 0.9, and so fits a line pretty well.  If I were to extrapolate based on the slope and intercept of the fit, I would expect my y values to be pretty close while the x values are close to the range of the data, but as my x values got farther out, I would expect more uncertainty.  What would be the best way to find how big the confidence interval is of y values.  So where 95% of scenarios so that match the same slope, intercept and r squared will pass through?

I have noticed that the confidence interval for predicted values in an linear regression tends to be narrow around the mean of the predictor and fat around the minimum and maximum values of the predictor. This can be seen in plots of these 4 linear regressions:    I initially thought this was because most values of the predictors were concentrated around the mean of the predictor. However, I then noticed that the narrow middle of the confidence interval would occur even if many values of were concentrated around the extremes of the predictor, as in the bottom left linear regression, which lots of values of the predictor are concentrated around the minimum of the predictor.  is anyone able to explain why confidence intervals for the predicted values in an linear regression tend to be narrow in the middle and fat at the extremes?


With tools like Process Hacker it's easy to find which Windows Services are being executed by an instance of svchost.exe, but this doesn't provide many informations.   Is there any way to find the CPU usage for each service?

Because my laptop fan was spinning up for no reason, I had a look at the CPU usage and I see  svchost with 12.5% CPU, which is basically a full core.  Now, I'm aware that  svchost runs services and I know how to display the services it runs in Task Manager or Process Explorer ().  Now I know which services are run, but I don't know which service eats the CPU time. I could disable one service after another, but I don't really like doing this (it could break things that are currently in use and I could forget turning the service back on later).  Therefore I'd like to know whether it's possible to instruct Windows to run only one service per svchost the next time I boot my PC. While I might have the slight disadvantage of several processes, I could immediately find out which one it is and it would be a much easier decision of whether or not to stop or restart the service.


What frequency means for a single photon?

I picture light ray as a composition of photons with an energy equal to the frequency of the light ray according to $E=hf$. Is this the good way to picture this? Although I can solve elementary problems with the formulas, I've never really been comfortable with the idea of an object having or being related to a "frequency". Do I need to learn quantum field theory to really understand this?


I know many politicians that avoid interview questions by talking a lot but not really communicating anything.  You could say that what they were saying was full of banalities or canned answers or that they were waffling, but is there a better word for this behaviour?  I'd like to say some thing like That response was a _____ or he\she is ___ing?

Some people write bloated books and long essays with skilful use of hooks, e.g. Jared Diamond; some others speak in long-drawn sentences with torrents of words, e.g. Noam Chomsky. It reminds me of a tactic politicians use in public discourse to waste people's time. I came across this word before but I can't retrieve it from either memory or the internet.


In my research I used a lot python libraries that I need to cite, I wonder if there is an accepted format for citing open-source software?  Do I just put them together with all other references? Do I create two separate references sections: "Article References", "Software References"? Or maybe there is another way to do it?  Just to be clear, I think I am good with the format of the citation itself, it is given , but I am not sure where do I put those citations in a paper.

When writing a manuscript for a scientific article, I often wonder what software I should cite or acknowledge, and how.  The first problem is to make a choice which software to cite. On the one hand, there is no way to cite all software, as this would mean to cite my whole software stack (Linux, GNU tools, emacs, git, ...). On the other hand, not citing any software is not fair, either. Furthermore, some software explicitly asks to be cited, some software doesn't. Also, some software is really crucial to the results, some isn't. Another important aspect is that citing software is not only about giving credit to the authors of the software, but also to give other scientists hints on what software they might want to use. So, the choice which software to cite is a problem.  The second problem is how to cite the software. Some (scientific) software does provide a classical scientific article that can be cited. However, in this case, no URL to the software is given. Others do not have an associated article. How do I cite these? I have seen people that cite the manual of a software, others just give the URL. What is the way to go?  Another aspect is where to cite the software. Some software can be cited in the course of the articles text, but when it comes to more fundamental software, other places may be more appropriate.  Are there any good ideas out there on any of these aspects?


I have an Olympus OMD EM5 and a Leica 25mm which takes wonderful pictures in daylight.  I was trying to take night pictures with this setup and I had the following results (after several tries and double-checking)  f/1.4, 1.3s extremely blurry    f/2, 3.2s sharp   f/3.2, 8s sharper   I don't understand why this would happen. Is there any phenomenon responsible for that?  Thanks!

Another question related to the Olympus OMD EM5. I bought this camera to replace my Nikon D90 and I'm very satisfied with it.   However, I find very hard to do the focus at night. With the Nikon D90, I could look through the viewfinder and use the focus ring to do a manual focus at infinity.  With the Olympus, the viewfinder is electronic and doesn't catch enough light, so it's impossible to do the focus visually. Not to say that the autofocus doesn't work at night. How do you deal with this? If I take a photo of a landscape, can I just turn the focus ring all the way to the right?  Thanks!


(or Gabriel's horn) is an example of a solid figure with infinite surface area and finite volume.  Is it possible to build the opposite (finite surface area but infinite volume) in an n-dimensional space? If not, how do we prove it?  More formally:   Let $S$ be an open subset of $\bf{ℝ^n}$ that is homeomorphic to $\bf{ℝ^n}$  and $S$ has infinite volume. If $T\cap \overline S\setminus S$  has a definable finite surface for every closed bounded $T\subset \Bbb R^n$, is it possible for $S$  to have finite area?

Is there any pathological shape that has a finite surface area but an infinite volume? Sort of like the opposite of a Gabriel's horn.


I can view all jpg images in a folder using the function :  $list = glob('../uploads/images/*.jpg'); usort(    $list,    create_function('$b,$a', 'return filemtime($a) - filemtime($b);') ); foreach($list as $file) {     echo '<img src="../uploads/images/'.basename($file).'"/>';    }   How do I get regular expression in the file format? I tried to accept jpg and JPG but did not work: $list = glob('../uploads/images/*.("%.+.[jJ][pP][eE]?[gG]$%i")');

I'm trying to display an array of files in order of date (last modified).  I have done this buy looping through the array and sorting it into another array, but is there an easier (more efficient) way to do this?


OS: Ubuntu 16.04 (Desktop enviroment)  HDD size: 1TB   De-Fragmentation: In Windows it is mandatory to defrag the hdd. Otherwise system will become slow. Is it required in Ubuntu or any Linux distro? If yes, Kindly guide me on the secure procedure. Currently I am using BleachBit. Dose it take care of all the maintenance required? Or do I need to do some other stuff?

Why is defragmenting unnecessary in Ubuntu?


I've made my own Camera object, with a forward vector as well as a up vector. I happen to be programming in Android using OpenGL ES 2.0 but I think this question is relevant to all frameworks, it seems to be some math issue I'm not understanding.  Here's a gif of my Pitch/Yaw working correctly:    Here's a gif of Pitch/Yaw in a circle, causing the square to rotate, because the camera is tilting (the up vector becomes negative as I continue).    Here's pseudocode for my pan/yaw functions:  function pitch(amount) {     if (amount == 0) return;     forward = normalize(forward + up * amount);      // Now fix the incorrect up vector     right = cross(forward, up);     up = normalize(cross(right, forward)); }  function yaw(amount) {     if (amount == 0) return;      right = cross(forward, up);     forward = normalize(forward + right * amount); }   I get the same issue if I use Vector rotations instead of Vector Addition (amount is an angle and I use a Rotation Matrix in the X or Y axis)  Pitch: forward = normalize(rotated(forward, angle, Vector3(1, 0, 0))); Yaw: forward = normalize(rotated(forward, angle, Vector3(0, 1, 0)));   Why is this happening? Is there a way to stop it?  EDIT: I followed the instructions at  to pitch using the local X axis and yaw using the world Y axis, same result.  Here's the new pseudocode:  function pitch(angle) {     if (angle == 0) return;      right = cross(forward, up);     forward = normalized(rotated(forward, angle, right));      // Fix the now incorrect up vector     up = normalized(cross(right, forward)); }  function yaw(angle) {     if (angle == 0) return;      forward = normalized(rotated(forward, angle, Vector3(0, 1, 0))); }   You can see all the code at

My goal is to program a camera to point towards the mouse cursor. I attached the following script to the Main Camera.   using UnityEngine; using System.Collections;  public class CameraController : MonoBehaviour {      public float sensitivity;      // Update is called once per frame     void Update () {         transform.Rotate (Input.GetAxis ("Mouse Y") * -1 * sensitivity, Input.GetAxis ("Mouse X") * sensitivity, 0);     } }   I "told" the camera to rotate around the x and y axes. Whenever it does this, the camera tilts sideways. When I checked the rotation of Main Camera, I saw that the z rotation had changed. Why is it rotating around the z axis when I left it at 0?


I recently visited a question with unformatted code. Before I could format it however, a low-rep user made an edit that was basically what I was going to do.  Here's the problem: I'm now not given the opportunity of just fixing the question like I normally could. I can only approve their edit, .  Why is it that I'm now blocked from simply fixing a question because someone else made an edit before me that requires approvals? If I can be trusted to carry out arbitrary edits on a question, it seems to follow that I should also be trusted to single-handedly approve an edit (or at least be allowed to still make my own). It's the same result: a single user allowing/causing an edit to happen to someone's post.  I think posts should be allowed to be edited as normal, even if there are pending suggested edits. I also think any user capable of making unchecked-edits to a post should also be allowed to single-handedly approve other edits.    I'll note though that this problem only seems to exist on the desktop site. When there's a pending edit, the edit button is replaced with a edit(#) button that brings up a review window instead of a direct editing screen.  In the app however, I can still make edits freely even when there's a pending suggested edit. The functionality doesn't change (likely due to limitations of the app).    (This stemmed from SO, but I believe it applies to the entire network.)

It's not consistent to leave an edit pending for approval (thus not making available for everyone else and locking its state) after a user who has those privileges have given his endorsement.   You could say why don't I improve the edit, but that makes no sense for something that is correct and it would not follow the "keep it simple" policy.  Update:  This is the current time line:   Someone who doesn't know about formatting makes a question. It's not legible A user without edit privileges amends the formatting. The correction is not visible, still not legible. I see the question and the pending revision and then cast my approval. It doesn't take effect yet, still not legible. Even for me if I didn't take care of copying the question source because it disappears from my own revision page!   I might agree that one's approval is indicative of both revision's quality and editor's competence. But we should retain that the main objective is to ask and answer questions. So, I propose this model:   Someone who doesn't know about formatting makes a question. It's not legible A user without edit privileges amends the formatting. The correction is not visible, still not legible. A user with edit privileges cast his approval. Revision takes effect. Although it keeps the pending approval (the Edit (1) button). If a second user with edit privileges cast a rejection, it also takes effect as a rollback.


Can we call matter without mass as energy? just a simple defintion to the word energy; massless matter= energy? and I'm not asking about photons.

Some physical quantities like position, velocity, momentum and force, have precise definition even on basic textbooks, however energy is a little confusing for me. My point here is: using our intuition we know what momentum should be and also we know that defining it as $p = mv$ is a good definition. Also, based on Newton's law we can intuit and define what forces are.  However, when it comes to  many textbooks become a little "circular". They first try to define work, and after some arguments they just give a formula $W = F\cdot r$ without motivating or giving intuition about this definition. Then they say that work is variation of energy and they never give a formal definition of energy. I've heard that "energy is a number that remains unchanged after any process that a system undergoes", however I think that this is not so good for three reasons: first because momentum is also conserved, so it fits this definition and it's not energy, second because recently I've heard that on general relativity there's a loss of some conservation laws and third because conservation of energy can be derived as consequence of other definitions.  So, how energy is defined formally in a way that fits both classical and modern physics without falling into circular arguments?


I'm having problems with a NullPointerException.  I was doing the debugging and the element is not null, I have the problem in the first IF and I can not see what the problem is. I thought that happened when the state of the element was null, but I tried to fix it and it did not work  // Update: The problem is when I Check the status  for (Items item : master.getItems()) { try {     if (item.getCompany_status().equals("active") || item.getCompany_status().equals("open")) {  if (item.getAddress_snippet() == null) {     cont2++;     Company c = new Company(item.getTitle(), "");                                 arrayCompany.add(c); }else {     cont2++;     Company c = new Company(item.getTitle(), item.getAddress_snippet());                                      arrayCompany.add(c); } } catch (Exception e) {      e.printStackTrace(); } } }

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


if observer 1 sees observer 2 moving toward  him at near the speed of light, observer 1 will say that his clock runs faster then observer's 2 clock, but observer 2 will see observer 1 toward him at near the speed of light, and observer 2 will say that observer 1 clock moves slower than his.  when they meet and compare clocks, what will the outcome be?

Suppose we have two twins travelling away from each other, each twin moving at some speed $v$:    Twin $A$ observes twin $B$’s time to be dilated so his clock runs faster than twin $B$’s clock. But twin $B$ observes twin $A$’s time to be dilated so his clock runs faster than twin $A$’s clock. Each twin thinks their clock is running faster. How can this be? Isn’t this a paradox?


How do I install Silverlight plugin in Ubuntu? And how to configure browser with Silverlight plugin?

I need Silverlight installed on my Ubuntu system, so that I can see some of the Microsoft websites(mainly videos).  Are there any alternatives to Silverlight in Ubuntu? If so, what are they and how do I install them?


This question's my profesors. I know $x^n$ is a pointwise convergent sequence. But I don't know how can I show that this limit. Can you show me solution of this question. $f:[0, 1]\rightarrow \mathbb{R}$ continuous function. $$\lim_{n\rightarrow \infty }\int_0^{1}x^nf(x) \, dx$$ Find the limit.

I am trying to solve the following problem at the level of a senior undergrad analysis level. So, the problem is as follows: We are given a function $f$ which is continuous on the interval $\left [ 0,1 \right ]$, and the question is to find the limit: $$\lim_{n\rightarrow \infty}\int_{0}^{1}x^{n}f(x)dx\;.$$ The second part of the problem is to deduce the following limit: $$\lim_{n\rightarrow \infty}n\int_{0}^{1}x^{n}f(x)dx\;.$$  For the first part: I just did the following: For every $0\leq x< 1$: $x\leq M$, where $0< M< 1$. Then: $$\int_{0}^{1}x^{n}f(x)dx\leq M^{n}\int_{0}^{1}f(x)dx\;.$$ Then: $$\lim_{n\rightarrow \infty }\int_{0}^{1}x^{n}f(x)dx\leq \lim_{n\rightarrow \infty }M^{n}\int_{0}^{1}f(x)dx= 0.\int_{0}^{1}f(x)dx=0\;,$$ so $$\lim_{n\rightarrow \infty }\int_{0}^{1}x^{n}f(x)dx=\lim_{n\rightarrow \infty }f(1)\int_{0}^{1}1dx=f(1)\;.$$ Does that make sense? If not, please show me the correct one.  As for the second part, I have no idea what to do. Any help?


Learning Android and Java.  I have lot of strings and tedious to type long methods chain so decided to create a class so can use on multiple fragments and activities.  This class method should allows to get string by it's name. For instance   Instead of using this code in fragment  getResources().getString(R.string.string_name);   I want result using the class method  utils.getStringItem("string_name");   Java Class  import android.content.Context;  public class Utils {     Context context;     String  resource;      public Utils(Context context) {         this.context = context;     }      public String getStringItem(String resource) {         String packageName = context.getPackageName();         int    resId       = context.getResources().getIdentifier(resource, "string", packageName);         return context.getString(resId);     } }   Fragment Class  import android.os.Bundle; import android.support.annotation.NonNull; import android.support.v4.app.Fragment; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup;  import java.util.ArrayList;   /**  * A simple {@link Fragment} subclass.  */ public class PlacesFragment extends Fragment {      ArrayList<Place>           mPlaces;     RecyclerView               mRecyclerView;     RecyclerView.LayoutManager mLayoutManager;     RecyclerView.Adapter       mAdapter;     Utils                      utils = new Utils(getActivity());       public PlacesFragment() {         // Required empty public constructor     }       @Override     public View onCreateView(             @NonNull LayoutInflater inflater, ViewGroup container,             Bundle savedInstanceState     ) {          View rootView = inflater.inflate(R.layout.fragment_places, container, false);          mRecyclerView = rootView.findViewById(R.id.recyclerView);          mPlaces = new ArrayList<>();          mPlaces.add(new Place(                 utils.getStringItem("string_name"),                 "content text goes here.",                 R.drawable.img.cdd,                 4.0f         ));          mRecyclerView.setHasFixedSize(true);         mLayoutManager = new LinearLayoutManager(getActivity());         mAdapter = new PlacesAdapter(mPlaces);         mRecyclerView.setLayoutManager(mLayoutManager);         mRecyclerView.setAdapter(mAdapter);          return rootView;      }  }   This is giving me error and app is getting crash on startup.  Error Message  java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference         at com.codepaints.myapp.Utils.getStringItem(Utils.java:14)         at com.codepaints.myapp.PlacesFragment.onCreateView(PlacesFragment.java:48)


I am trying to minimize my typing with creating a few scripts, but I'm stuck.  echo "Creating the plex.tar.gz" dd if=plex.bin of=plex.tar.gz bs=200 skip=1; sync echo "I am now unpacking the plex.tar.gz" tar -zxf plex.tar.gz echo "It should all be done"   and I keep getting  xx:~/plex$ sudo ./plex_create Creating the plex.tar.gz 510616+1 records in 510616+1 records out 102123230 bytes (102 MB, 97 MiB) copied, 1.43576 s, 71.1 MB/s : not foundte: 2: ./plex_create: sync I am now unpacking the plex.tar.gz tar (child): plex.tar.gz\r: Cannot open: No such file or directory tar (child): Error is not recoverable: exiting now tar: Child returned status 2 tar: Error is not recoverable: exiting now It should all be done xxx@xxx:~/plex$   What I would require would be actually text and running command, when done, text, another command and so on.  Thank you very much.

This is my script:  #!/bin/bash hd='pwd' cd $hd   When I try to run it, it fails with:  line 3: cd: $'pwd\r\r': No such file or directory   What is going on?


I am trying to upgrade to the newest LTS. What am I missing here? chris@chris-x1 ~> lsb_release -a  No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 18.04.5 LTS Release:    18.04 Codename:   bionic  chris@chris-x1 ~> sudo do-release-upgrade  Checking for a new Ubuntu release There is no development version of an LTS available. To upgrade to the latest non-LTS develoment release  set Prompt=normal in /etc/update-manager/release-upgrades.  Update with resolution  Run software-properties-gtk In the Ubuntu Software tab I selected the first 4 checkboxes (probably too many). This updates a bunch of caches Ran sudo do-release-upgrade  At this point the installation was kinda wonky. I had missing icons and my theme customizations were MIA. Couldn't run upgrades due to broken packages so I ran sudo apt dist-upgrade and this seemed to resolve everything. I can sort out the rest later.

I understand that the first point release of Ubuntu 18.04, namely 18.04.1 is now available and that my system should now offer it as an update.  My current OS version is 16.04.5 LTS. In System Settings/Software and Updates I have set 'Notify me of a new Ubuntu version' to 'For long term support versions'. I have tried both the main server and the server for United Kingdom, neither offers an update when Software Updater is clicked or via the Ubuntu Software icon.  Can anyone please tell me why I don't get the option of updating to 18.04?  Edit:  I don't remember the details exactly, but I think that my last LTS point release update was offered automatically a lot sooner after the published release date than where we are now with 18.04.1.  Edit 10th August  It appears that there has been some problem with the update process and that it should be fixed next week, see:    Edit 14th August 18.04.1 LTS now available from UK server,


Lately I noticed wired stuff in my computer like files disappearing, a restart without a reason no warning or notification just restarted suddenly, so I thought maybe someone is assessing my computer remotely than I checked the event log it haven't been logged the file disappearence and the restart, also when I opened the task manager the cpu usage is high after 1 second at most the usage drops and the application list change, so how do I make sure that my computer is being accessed remotely and how I prevent it from happening again and if is possible I want to know who is accessing it.  Note I have kaspersky installed but before I install it I used the computer With out anti virus.

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


So I have this problem that I want to have a factory / manager class UserManager that manages Users. And Users have both UserType1 and UserType2 extending to it.  currently I have this for UserManager.   public abstract class UserManager<T extends User> {     // T is either UserType1 or UserType2     public ArrayList<T> users; }   Now I want to create UserType1 or UserType2 depending on conditions, e.g.  public T create(boolean isType1) {     if(isType1) // create UserType1     else // create UserType2 }   And I can't just do  T newUser = new T();   I'm stuck, any help is appreciated!!

Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is no (due to type erasure), but I'd be interested if anyone can see something I'm missing:  class SomeContainer<E> {     E createContents()     {         return what???     } }   EDIT: It turns out that  could be used to resolve my issue, but it requires a lot of reflection-based code, as some of the answers below have indicated.  I'll leave this open for a little while to see if anyone comes up with anything dramatically different than Ian Robertson's .


Suppose I consider the affine cipher defined by $E(x) = ax + b \bmod n$  on the standard alphabet of 26 letters. Which choices of $a$ and $b$ lead to proper encryption functions?  Using the information provided from this :  They say that $a=5$ and $b=8$ works, but $a=4$ and $b=5$ does not work.  My understanding is that in cases where it does not work then different letters prior to applying this cipher results in the same ciphertext having applied the cipher.  However, I consider this explanation to be quite woolly. How would I know which choices would work prior to applying the cipher?

In the , the key $k = (a, b)$ should have the following property, i.e. GCD of $a$ and the modulus should be 1:     $\gcd (a, m) = 1$, where $m$ is the set of possible moduli   My question is, why it is required that $a$ should have the above property? What is the significance of this? And why is $b$ excluded from this condition?


The USDA nutrition data says these foods have much better nutrition raw than cooked.  Can I make them safe to eat without cooking?   Expand them and soften with water so they don't grow after being eaten Remove anti-nutrients and indigestible parts.   Can they be sprouted? Or soaked with lemon juice?  Or if I boil them, does the water contain the removed nutrients and can I eat that?

I searched Google with the following keywords:     calories in 1 tbsp brown rice   The result was:        As you can see the calories, after cooking have severely reduced.   What can I do to maintain the default level of calories in cooked rice?  I am not talking about increasing calories by adding extra materials like oil. I wish to know some cooking method which does not destroy the calories so much.  Note: I do NOT throw any water during the process of cooking rice.


I recently installed Ubuntu 20.04 dual-boot alongside pre-installed Windows 10 on my laptop (on the same SSD disk, but separate partitions) with a UEFI boot loader.  now I can not write, create or edit anything on my NTFS HDD partitions. I've searched for the problem and tested the below configuration for the mount point in /etc/fstab but unfortunately, it doesn't work.  LABEL=Learnings /mnt/Learnings ntfs rw,exec,users,umask=000,dmask=000,fmask=000,uid=1000,gid=1000,x-gvfs-show 0 0   this is the ls -l command result on an NTFS partition which denotes I have the right access to files and folders.  -rwxrwxrwx 1 mohsen mohsen    78 Feb 16 21:30  /mnt/Learnings/Note.txt drwxrwxrwx 1 mohsen mohsen     0 Apr 23 21:56  /mnt/Learnings/TEMP   also, it should be noted that:   I've disabled the hibernation mode in windows 10 with powercfg.exe /hibernate off command. I'm not sure if it relates, but I've recently twice experienced the blue screen page on Windows while I was backing up the disk and also while I was trying to restart the OS.   Thanks in Advance, Mohsen.

When I try to do a ntfsck to a NTFS partition I get this:  sudo ntfsck /dev/sdb1 Unsupported: replay_log() Volume is dirty. Unsupported: check_volume() Checking 161792 MFT records. Unsupported cases found.   How can I clean a "dirty" NTFS volume without having to actually use windows chkdsk tool in the NTFS volume.  I also did a ntfsfix and it said that everything was OK but it actually was not.  I also get the same "Dirty" error when trying to check the filesystem using the Disk Utility:    I am starting to think I need some powerful soap.


I think I remember reading that a function $f:A\rightarrow B$ is a subset of $A\times B$ such that for each $a\in A$ there is exactly one element of $f$ such that $\{a\}\in F$ (assuming $(a,b) = \{\{a\},\{a,b\}\}$, although I guess this detail isn't important probably). Wouldn't this definition mean that we cannot know what the codomain of the function is?

A function $f$ is defined as a set of ordered pairs $(x, y)$ such that $(x,b), (x,c) \in f \Longrightarrow b=c$. Since $y$ is determined uniquely by $x$, it is customarily denoted $f(x)$.   One difficulty I am having with this definition is that it does not specify the codomain. In particular, $f:\mathbb{R} \rightarrow \mathbb{R}_{+}$  such that $f(x)=\exp(x)$ and $g:\mathbb{R} \rightarrow \mathbb{R}$ such that $g(x) = \exp(x)$ would be the same functions under this definition.   But this is absurd. One is bijective, the other is not.


When I use chromium-browser this happen   $ chromium-browser [15136:15170:0301/012914.214743:FATAL:nss_util.cc(631)] NSS_VersionCheck("3.26") failed. NSS >= 3.26 is required. Please upgrade to the latest NSS, and if you still get this error, contact your distribution maintainer. Aborted (core dumped)   I found that this might help, but it did not work:  $ chromium-browser --disable-extensions [15208:15242:0301/013019.381998:FATAL:nss_util.cc(631)] NSS_VersionCheck("3.26") failed. NSS >= 3.26 is required. Please upgrade to the latest NSS, and if you still get this error, contact your distribution maintainer. Aborted (core dumped)   When I use launcher the icon shows in the dock, then disappears.

I upgraded to Chrome 61.0.3163 via ppa on Ubuntu 16.04 but it won't launch because NSS out of date. Launching Chrome in terminal gives:  NSS >= 3.26 is required. Please upgrade to the latest NSS, and if you still get this error, contact your distribution maintainer.   Running   sudo apt-get install libnss3   gives  libnss3 is already the newest version (2:3.21-1ubuntu4)   Should I try to get a newer version of libnss that's not in the repository? I downgraded my version of Chrome for now.  Edit:  apt-cache policy libnss3 libnss3:   Installed: 2:3.21-1ubuntu4   Candidate: 2:3.21-1ubuntu4   Version table:  *** 2:3.21-1ubuntu4 500         500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages         100 /var/lib/dpkg/status  cat /etc/apt/sources.list # deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted  # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://us.archive.ubuntu.com/ubuntu/ xenial main restricted # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial main restricted  ## Major bug fix updates produced after the final release of the ## distribution. # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial-updates main restricted  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## universe WILL NOT receive any review or updates from the Ubuntu security ## team. deb http://us.archive.ubuntu.com/ubuntu/ xenial universe # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial universe # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial-updates universe  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu  ## team, and may not be under a free licence. Please satisfy yourself as to  ## your rights to use the software. Also, please note that software in  ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://us.archive.ubuntu.com/ubuntu/ xenial multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial-updates multiverse  ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. # deb-src http://us.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse  ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. deb http://archive.canonical.com/ubuntu xenial partner deb-src http://archive.canonical.com/ubuntu xenial partner  # deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted # deb-src http://security.ubuntu.com/ubuntu xenial-security universe # deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse


When entering from a rarer to a denser medium, the speed of light decreases.I know that the frequency remains constant.But if frequency is cycles/sec then doesn't that mean more speed will lead to more cycles/sec? and if the wavelength changes, should i see a different color all together? I'm not familiar with the 'complicated math' so is there another way to understand?

What determines the color of light -- is it the wavelength of the light or the frequency?  (i.e. If you put light through a medium other than air, in order to keep its color the same, which one would you need to keep constant: the wavelength or the frequency?)


I'm looking for a  that can take full page screenshots. I am aware there are various extensions, but haven't found any that would take full page images.

Is there some way in Safari, possibly via a third-party extension, to save the running contents of a Web page as a PNG image?  I understand I could print the page to PDF and use Preview to export it as a PNG image. However:   I’d prefer not to create a temporary PDF file and then manually open Preview to export the PDF contents to PNG; I’d like the contents to be running instead of paginated, i.e., no page breaks; When the PDF file contains multiple pages, Preview seems to export the current page only to PNG.   I don’t have any experience with OS X automation but I suspect it could be used for this, though I want conditions 2 and 3 to be met.  I’m running Safari 5.1.1 on OS X Lion.


I have a very simple script reading a text file which is in a different directory:  IFS=$'\n' read -d '' -r -a urls < ../dat/urls.txt   This works fine when running the script from the directory the script is in e.g) ./fetch_urls  But if I run the script from the say the user home or via cron it fails to resolve the urls.txt file. e.g.  /home/my-user/data-transfer/fetch_urls.sh   It fails with:  line 3: ../dat/urls.txt: No such file or directory   Is there some way to make it work so it always resolves correctly the urls.txt file. Or maybe I have to pass the location of urls.txt as a parameter?

How do I get the path of the directory in which a  script is located, inside that script? I want to use a Bash script as a launcher for another application. I want to change the working directory to the one where the Bash script is located, so I can operate on the files in that directory, like so: $ ./application


java.lang.NullPointerException: Attempt to invoke interface method 'org.andengine.opengl.texture.ITexture org.andengine.opengl.texture.region.ITextureRegion.getTexture()' on a null object reference          at org.andengine.entity.sprite.Sprite.preDraw(Sprite.java:243)         at org.andengine.entity.Entity.onManagedDraw(Entity.java:1354)         at org.andengine.entity.Entity.onDraw(Entity.java:1162)         at org.andengine.entity.Entity.onManagedDraw(Entity.java:1385)         at org.andengine.entity.Entity.onDraw(Entity.java:1162)         at org.andengine.entity.Entity.onManagedDraw(Entity.java:1385)         at org.andengine.entity.scene.Scene.onManagedDraw(Scene.java:260)         at org.andengine.entity.Entity.onDraw(Entity.java:1162)         at org.andengine.engine.Engine.onDrawScene(Engine.java:627)         at org.andengine.engine.Engine.onDrawFrame(Engine.java:617)         at org.andengine.opengl.view.EngineRenderer.onDrawFrame(EngineRenderer.java:105)   getting nullpointer exception. Does not get any idea to solve it.

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


The question gave the hint that :For any invertible matrix B,rank(AB)=rank(A)and rank(BA)=rank(A).  I was thinking to prove that λI−A is invertible, hence by the property of the rank of matrices given, rank(λI−A)=rank((λI−A)^2).  However I realized that since λ is an eigenvalue of A, the det(λI−A) is zero hence is not invertible. Is there anyway to prove this?

Let $A$ be a diagonalizable matrix and $\lambda$ be an eigenvalue of A. Prove that rank($\lambda I - A$) = rank(($\lambda I - A)^2$).  The hint they provided is that for any invertible matrix B, rank(AB) = rank (A) and rank(BA) = rank(A).


I have created a business  for a client of mine. The client runs a business of providing therapeutic and behavioral services to youth and families experiencing developmental, emotional, and behavioral challenges.  The company is called Progressive Option Support Services. The client wanted to optimize the website so it can show up in the top of google search results when you search for "progressive option support services". I have no previous experience in SEO so I followed few blogs and articles on how I can improve the search ranking of the site and implemented it. Some of the things I did were:   Using h1 tag in the website Giving a proper meta description, title etc for the site Making sure there are no broken links. Giving a proper value to the alt attribute of an html image element. Creating a sitemap.xml and submitting it to google search console. Creating a robots.txt file. Making sure there are no canonicalization issues with the site. Using the keywords the client wants to associate with the business on the site and meta description.   However when the client searches for "progressive option support services" the first result she gets is the website for Progressive Insurance. It's not a sponsored advertisement, its the actual progressive insurance website.   However if you google "progressive leasing", you will see the following search result:    So it makes me think that whatever SEO optimisation I did for the site is not working. When I google "progressive option support services" on my browser I see the site I created.    So I do not know why the client see's Progressive Insurance website in the top of the search result whereas I see the actual website. The client and I are in different geographical regions (New Jersey, USA and Mumbai, India), so maybe that might be the deciding factor on why she sees the insurance company and I don't. But by that logic when she searches "progressive leasing" - she sees the result for progressive leasing (the first image).  Another question I had was how can I show my search result the way Progressive Leasing shows up, i.e the sitmap below the search result?  Here is the github link of the website code:   Any suggestions and/or modifications which will help the site show up will be very appreciated.  Thank you all.

What are the best ways to improve a site's position in the Google search results?


I'm new to python. I tried to store bunch of strings to an array and at the end print out the array, however it print out as a long list of characters. here is my code:  user_with_no_records = [""] for user_test_docs in json_data['results']:    ... do something here ...    user_with_no_records.extend(user_test_docs['userId'].replace("'", '"')) ... pprint(user_with_no_records)   instead of print out :  "1234-4a20-47c0-b23c-a35a", "53dd-4120-4249-b4f6-ebe2"   it print out  "1","2","3","4","-","a","2","0"....

What's the difference between the list methods append() and extend()?


I can't find my terminal window, I just installed version 12.04.3, Help..

What is a terminal? How do I open a terminal window? How do I use the terminal?


I have problem with inputing eps files from Matlab in my latex document.   Matlab version is R2016a. Windows version is 10, editor is Texmaker 5.0.3, MikTeX is version 2.9.  The first case is when I use latex + dvips + pstopdf build option, with using \usepackage{graphicx}. As a result I got compiled pdf, it shows some eps files, but it does not show eps figures which i generated from Matlab. Exactly, it cutted my document at the place where I inserted eps figure with includegraphic command.  The second case is when I use pdflatex build option, with \usepackage{epstopdf}. It compile my document, without any cuts, only places where need to be figures from Matlab are empty. Caption of missing figures also exists.  I tried to generate again Matlab figures, even with different combination of extension, for example as -deps, -depsc, -deps2, -depsc2, but I got the same result. I am not sure is that some Matlab bug, or Latex?   When I open eps file from Matlab with GIMP, it has proper content, it exist, I cannot see why, after compiling, it is not in pdf?  This is log file, from the second case:

I wish to  include eps images generated from Matlab plot (pdf is generated by Matlab as a whole page, that's why eps), however the conversion fails, leaving blank pdf image. The messaghe is:  MiKTeX GPL Ghostscript  9.25: Unrecoverable error, exit code 1    Sorry, but "MiKTeX EPS-to-PDF Converter" did not succeed. The log file hopefully contains the information to get MiKTeX going again: C:\Users\Andrey\AppData\Local\MiKTeX\2.9\miktex\log\epstopdf.log   The content of the log file  2019-12-03 06:29:05,797+0100 INFO  epstopdf - starting with command line: epstopdf --outfile=images/kkk-eps-converted-to.pdf images/kkk.eps 2019-12-03 06:29:06,456+0100 FATAL epstopdf - Invalid argument 2019-12-03 06:29:06,457+0100 FATAL epstopdf - Info:  2019-12-03 06:29:06,457+0100 FATAL epstopdf - Source: Libraries\MiKTeX\Core\Stream\FileStream.cpp 2019-12-03 06:29:06,457+0100 FATAL epstopdf - Line: 68   I have recently installed and updated Miktex and compile with LuaLatex.  Here is the  content of the eps, if needed   What is wrong with it? I have no idea what to do about it.  Update  First of all I'd like to that I do compile with --shell-ecape (from TexStudio)  Process started: lualatex.exe --shell-escape -synctex=1 -interaction=nonstopmode    I tried suggestion from Christian Shenk. The command is   mgs.exe -q -sDEVICE=pdfwrite -dSAFER -dAutoRotatePages=/None -dPDFSETTINGS=/prepress -dMaxSubsetPct=100 -dSubsetFonts=true -dEmbedAllFonts=true -sOutputFile=images/kkk-eps-converted-to.pdf - -c quit   I tried to execute it  in command processor. It creates a 0 byte pdf file and gets  stuck.  Update 2  I executed  epstopdf --outfile=images/kkk-eps-converted-to.pdf images/kkk.eps   And I did get additional information  Error: /invalidfont in /findfont Operand stack:    Helvetica-BoldOblique Execution stack:    %interp_exit   .runexec2   --nostringval--   --nostringval--   --nostringval- -   2   %stopped_push   --nostringval--   --nostringval--   --nostringval--   false   1   %stopped_push   2015   1   3   %oparray_pop   2014   1   3   %oparray_pop   --nostringval--   1998   1   3   %oparray_pop   1884   1   3   %oparray_pop   --nostringval--   %errorexec_pop   .runexec2   --nostringval--   --nostringval--   --nostringval--   2   %stopped_push   --nostringval--   1967   1   3   %oparray_pop Dictionary stack:    --dict:973/1684(ro)(G)--   --dict:0/20(G)--   --dict:123/200(L)-- Current allocation mode is local   I have no clue how I can fix it. It mentions something about "Helvetica-BoldOblique", but the images don't use it, but regular Helvetica.


Really sorry about the title, if there is any appropriate one please do change it to that.  I have written below sample code to understand virtual functions.   class A {     public:     virtual int f() {cout << "1";}; }; class B : public A {     public:     int f() {cout << "2";} }; int main() {     A a = *new B();     A* c = &a;     c->f();     A* pa = new B();     pa->f();     B* b; }   The above code outputs 12, I expected that it would print 22.  I thought when a virtual function is invoked from a pointer, it gets dynamically binded. So, I don't understand why the above output is different.

Someone mentioned it in the IRC as the slicing problem.


Can someone help me with the integral     $ \int_{0}^{1} \frac{x^2-1}{\log{x}} dx $   Tried substitution $ u = \log{x} $ but nothing came out. Thanks to helpers.

How to figure out the following integral? I have not been able to solve it from some time. $$\int_0^1\frac{x^{2} -1}{\log x}\,dx$$


A short while ago I had posted about adding a comma to the value once it reached a certain number (1000).   At the moment, the value is going up $11 every second, although I would like to implement a change so that it goes up $11.43 every second.   For example: 0, $11.43, $22.86 ... and then when it reaches $1000 it should have the comma ($1,024.56). You should get the drift.  Here is my jsFiddle:   var millisecs = 1000; setInterval(function() {     var $badge = $('#badge');     var num = parseInt($badge.text().replace(',', ''))+11;     $badge.text(num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",")); }, millisecs);   Any help will be much appreciated.  Cheers

I would like to format a price in JavaScript. I'd like a function which takes a float as an argument and returns a string formatted like this: "$ 2,500.00"  What's the best way to do this?


FILE:  I'm doing motion tracking scene and the objects that I put in are not rendering. They are rendering in viewport and in other places but not in the final render. The shadow catcher seems to not work too. I didn't pack the background movie, it's too heavy.   I tried:       FIRST Image is how it should looks like (taken from viewport) SECOND is how it looks

This is meant to solve this problem once and for all. What is every reason an object isn't showing up in a render or viewport in when using the cycles render engine?


Find  $$\lim\limits_{n \to ∞} \frac{{\sqrt 1}+\cdots+{\sqrt n}}{n{\sqrt n}}$$  The series in the numerator is what throws me off.  I have tried just about everything, I'm stuck on how to write it in a form where I can find the limit.

$$\lim_{n \to \infty} \dfrac{\sqrt 1 + \sqrt 2 + \dots + \sqrt{n}}{n\sqrt{n}}$$   $$\lim_{n \to \infty} \dfrac{\sqrt 1 + \sqrt 2 + \dots + \sqrt{n}}{n\sqrt{n}} =\lim_{n\to \infty} \dfrac1{n}\sum^{n}_{k = 1} \sqrt{\dfrac k n} $$  While searching this question I found, .   Like in the accepted answer I first compared my series to LRAM,    $$\int_a^b f(x)\,dx=\lim_{n\to\infty}\frac 1n\sum_{i=1}^n f\left(a+\frac{b-a}n i \right)$$  I got $a = 0$, $b = 1$ and $f(x) =\sqrt{x}$ so,  $$\int_0^1 \sqrt{x}\ dx = \dfrac2 3$$ should be the answer.  Is there any simpler method to do this sum ? I have not learnt this method to do infinite sums so I can't use it.


I recently did a backup of a table,compressed it and partition it.Then I did replication to it using the filter option to get latest data.Now I can only see the latest records and not the old records but the ndf files are there. Is there a way to recover these records?I mean tie back the partition to this table so that I can see the data?

We have 2 servers:  Server A. production (no partitions) Server B. New Server (partitions and compression)  We restored a backup to the new server, partitioned a large table by datetime and turned on compression, and we were happy. Trying to be clever, we turned on replication to update the new server with the latest data on the large table, but that broke the partitioning and compression. We cannot query any old data on the new server, only data from when we turned on replication. The clustered index is the old one, and compression is not on, and no partitions to be seen in SSMS, it's using the PRIMARY filegroup  (same as the current live server is using). On the physical disk, I can see the partition files, and they are still massive with GBs of data, so I know the data is there, but it appears the table has lost the link to it. It appears turning on replication replicated the filegroup side of things. Is there a way to point the table back to partitions and save all the work we did getting it ready for switch over? It's a pretty large database. This one table is 11TB on the production server. SQL Server 2017 Enterprise Edition.


I am working towards completing my undergrad honours thesis and I am in the process of analyzing and writing up my discussion section that is dealing with some form of multiple regression (can't figure out which it is based on my data and what my professor is looking for - In our meetings she can never articulate what I am looking for properly so I just agree and find my answers elsewhere). I have done stats in the past (Worked in SPSS), had no problem in the class with regression, but we only dealt with regression relationships that had 1 dependent and 1 independent variable (y = a + bX). In my analysis I am running 5 different models, with the first model having 1 dependent, and 2 independent, the next has 1 dependent and 3 independent, etc.   The Issue: In the final coefficient table in SPSS after running a regression analyses, I am having troubles understanding how/ why/ the meaning of the values changing. Please correct me if I am wrong, but when you run a regression analyses with multiple independent variables and 1 dependent variable, your answer will look something like this: Lets say for this example there are 2 Independent variables, variable 1 is significant, and variable 2 is not significant: "Variable1 has an impact on the dependent variable while controlling for variable 2. Variable 2 has no impact on the dependent variable while controlling for variable 1"  I am somewhat certain this statement is correct although rather limited in its meaning in the data. At this point that is ok as I can get assistance making this statement stronger within the thesis. My question then is as follows: What is meant by 'controlling for variable 1/ 2'? When we say controlling for, what is actually going on? How is the data actually controlling for it? The way I'd understand it is from a simple equation like this:  Constant (B = 5), Variable 1 (B = 10, Sig. = 0.04), Variable 2 (B = 15, Sig. = 0.98)   y = 5 + 10(x) + 5 + 15(x).  From here, if we were examining variable 1 controlling for variable 2, I am thinking the  equation would then turn into:  y = 5 + 10(x) + 5 + 15(0) so we'd be left with y = 5 + 10(x) + 15?   Sorry to make this post extremely long but thank you for you in advance for any assistance in the matter.  TLDR: What does 'controlling for' mean in a hierarchical or standard or multivariate regression analysis? Please explain in the simplest terms as I am not a stats major nor will I understand complex responses.   Thanks again,  Michael

Here is the article that motivated this question:   I liked this article, and it nicely demonstrates the concept of “controlling for other variables” (IQ, career, income, age, etc) in order to best isolate the true relationship between just the 2 variables in question.    Can you explain to me how you actually control for variables on a typical data set?      E.g., if you have 2 people with the same impatience level and BMI, but different incomes, how do you treat these data?  Do you categorize them into different subgroups that do have similar income, patience, and BMI?  But, eventually there are dozens of variables to control for (IQ, career, income, age, etc)  How do you then aggregate these (potentially) 100’s of subgroups?  In fact, I have a feeling this approach is barking up the wrong tree, now that I’ve verbalized it.  Thanks for shedding any light on something I've meant to get to the bottom of for a few years now...!


Reading about category theory a category is a collection of objects "types" that have morphisms "transformations" with two properties: Associativity: for every object all its morphisms should be associative when composed together. Identity: for every object must have one identity morphism which doesn't change any of his other morphisms when it is composed with them. So associativity seems like a reasonable property that ensures correct composition. but why is identity important? what purpose does it serve? and why is it called "identity" and not just "neutral morphism"? And why do some categories like "magma, semigroup" don't have identity or associativity but are still called categories? for anyone else that comes here: ignore this link  and go directly to this link   it is possible to define isomorphisms without identities, but it is a bit more complicated and less elegant. I think you're reading far too much into Eilenberg and Mac Lane: they weren't trying to make some "universal" definition that applies to every situation imaginable; they were just making a natural-seeming definition that works in all the relevant examples they could think of." Considering "associative" operations which don't have identities is thus analogous to considering finite sets but not allowing the empty set. Of course, this is sometimes useful to do, but unless you have a good reason to, it is probably not the natural thing to do.  Thank you PrudiiArca for your help and special thanks to Eric Wofsey for the answer

One common definition of a category features objects, arrows, an associative composition law for arrows, and an identity map requirement: for every object there must be an self-pointing arrow that behaves as left-side and right-side identity for composition.  I have no problem seeing how one could use a formalism of objects and arrows between them to structure our thoughts on a wide variety of areas.  Also, it's easy to see why one would want to have a basic building operation (i.e. the composition law) in such a formalism.  With a little more thought I can also see why one would stipulate that this composition law be associative: making composition associative has the effect of replacing the "pair of arrows" with the "sequence of arrows" as the formalism's basic building operation, and I can see that this change may make the formalism more flexible.  I can't come up with any rationale at all for requiring that there be an identity arrow for every object.  What is lost by dropping this requirement?  Note that dropping this requirement does not preclude the existence of identity arrows, and therefore, it does not preclude defining concepts (e.g. inverses, isomorphisms) that depend on the concept of an identity arrow.  In fact, AFAICT, if one were to drop the identity arrow requirement, one could still define functors, natural transformations, cones, etc. (except that the definitions, of course, would not have the usual stipulations for the identity).  EDIT: To sharpen the question a bit, and maybe make it less of a "philosophical issue", I note that several times I've come across remarks from Saunders Mac Lane to the effect that their aim (his and Eilenberg's) in coming up with category theory was to arrive at the concept of natural transformation.  In fact, in , Mac Lane writes (p. 18):     "category" has been defined in order to define "functor" and "functor" has been defined in order to define "natural transformation".   As I noted earlier, the definitions of functor and natural transformation don't seem to rely much on the identity law requirement for categories.  So I could make my question a bit more concrete: how does requiring that every object in a category have an identity contribute to what Eilenberg and Mac Lane were aiming for?


I am reading a the proof of a theorem that says that $3$-perfect codes can only have length $7$ or $23$. I do not understand the following:  It follows from the definition that if $n$ is the length of a $3$-perfect then we must have that $(n+1)((n+1)^3-3(n+1)+8) = 3 \cdot 2^k$ for some $k \in \mathbb{Z}^+$. Now the proof claims that $16$ can not divide $(n+1)$.  I do not why. Any help or hints appreciated.

I'm trying to solve an exercise from the book Fundamentals of Error Correcting Codes, can somebody help me? The problem is the following:     Let $C$ be an $[n, k, 7]$ perfect binary code.       (a) Using equality in the Sphere Packing Bound, prove that      $$(n+1)[(n+1)^2 −3(n+1)+8]=3·2^{n−k+1}.$$      (b) Prove that $n+1$ is either $2^b$ or $3·2^b$ where, in either case,   $b≤n−k+1$.       (c) Prove that $b < 4$.       (d) Prove that $n=23$ or $n=7$.       (e) Name two codes that are perfect $[n, k, 7]$ codes, one with $n = 7$   and the other with $n = 23$.   For part a) I could easily prove the claim :)  For part b) I answered in the following way:     From part a) we know $n+1=(3·2^{n−k+1})/(n^2-n+6)$, so since $n$ is a   natural number, then so is $n+1$ and thus we can consider three cases:   1) $(n^2-n+6)$ divides $3$ (it does not divide $2^{n-k+1}$) -> $n+1=2^{n-k+1}$   OK       2) $(n^2-n+6)$ divides both $3$ and $2^{n-k+1}$ -> $n+1=2^b$ with $b<=n-k+1$ OK        3) $(n^2-n+6)$ divides $2^{n-k+1}$ (it does not divides $3$) -> $n+1=3·2^b$ with $b<=n-k+1$ OK   I'm really not sure if it's enough to prove the claim or if there is some "more mathematically" proof. any suggestion?  For part c) I'm completely lost. I cannot find a way to prove that $b<4$. (I tried to use the information that $C$ is a perfect code. but I'm stuck!) & also for part d) & e) I need any suggestions.


In the following standard \documentclass{book} all headers are in upper case.   How can I modify the code below to make lower case headers?  The even pages show the chapter number and name, and the odd pages show the section number and name. The first page of a chapter has no header, only the page number in the footer. The other pages show the page numbers on the headers: odd pages on the right and even pages on the left, as shown.      It was created with  \documentclass{book} \usepackage{lipsum}  \begin{document}  \title{Standard \LaTeX{} Book} \author{The Author} \date{The Date} \maketitle \tableofcontents  \chapter{Test Chapter One} \section{Test Section One} \lipsum[1-6] \section{Test Section Two} \lipsum[1-6] \section{Test Section Three} \lipsum[1-6]  \chapter{Test Chapter Two} \section{Test Section One} \lipsum[1-6] \section{Test Section Two} \lipsum[1-6]  \end{document}   Remark: the question   is not sufficiently similar to this one to help me to find a possible solution by my own.

I am writting my thesis. I don't want the headers in each chapter to appear just in capital letters. Can I override the class file to get the header as " My First Chapter"?


According to the 13.04 release schedule, the Beta 2 release for 13.04 was made available today (April 4). Does anyone know where I can download it? Thanks!

I'd love to test the latest Ubuntu alpha/beta (otherwise known as "Ubuntu+1"), but I can't find it.   Where can I find download for the pre-releases of Ubuntu?


I want to install Python 3.9 in Ubuntu. When I run sudo apt-get python in the terminal it says that it will install Python 2 which I don't want. When I type sudo apt-get install python3.9 it shows that it is an invalid operation. How do I install Python 3.9?

How can I install a different version of Python using apt-get?  Obviously I realise I can install using the source tar ball, however I would prefer not to install from source and instead use the package manager, as that's what it's there for. Surely somewhere reputable builds .deb files for the latest Python releases (why python.org don't is beyond me) that I can reference.   What do I need to do to reference them and what issues might it create when upgrading to the next version?  If there is no way except for building from source, is there a (pseudo) package that I can can install that will provide all of the dependencies needed without having to find and install each individually? So that I don't get:  The necessary bits to build these optional modules were not found: _bz2                  _curses               _curses_panel       _dbm                  _gdbm                 _lzma               _sqlite3              _ssl                  _tkinter            readline              zlib


I am trying to migrate user accounts from a Drupal 7 site to a Drupal 8 site.  On the Drupal 8 site, I have a module that programmatically adds users using the following code.  $user = User::create(); $user->uid = ''; $user->setUsername('test'); $user->setEmail('test@abc.com'); $user->set("pass", $S$E96L22SibwKw5GrZrrCqCz7mxSjr9Z2pSB3GqBs5eeheTBPxOlJc); /*hashed value*/ $user->save();   The module creates the accounts correctly, but the user passwords are re-hashed.

I want to migrate some users from my Drupal 7 installation to a new Drupal 8 installation. I do not want to migrate the whole site or any content. And I also do not want to migrate all users.  The problem is the password; I can export from Drupal 7 and import users to Drupal 8, but the passwords do not work anymore. I've also tried to update the hashes (password) in the database directly; so I copied the password fields from Drupal 7 to Drupal 8. That also doesn't work; I think the salt changed in Drupal 8.  Is there any solution for this?