On trying to install Ubuntu 12.10 Desktop amd64 to a desktop pc using a ga a75 ud4h motherboard (which is using an AMD 3870k APU with a new 1TB HDD) following the advice in the  and  have now got to grub option screen for EFI install. Booting live dvd in EFI mode gives "Secure Boot is not enabled" just before grub kernel option list shows.  If the option to "Install Ubuntu" or "Try Ubuntu without installing" is selected gives "can not read cd/0" and "the kernel must be loaded first" errors. Using DVD or USB installation media gives same results and there has never been at any point an UEFI entry in bios/firmware settings or boot device list/s. It might be helpful to say that have had an alternative non-linux OS installing EFI mode on this hardware giving a GPT installation automagically using USB installation media when the hdd space was completely unallocated space. The USB device was listed under hard drives in bios/firmware one time boot list and did not have an UEFI entry. i.e. it installed EFI although no EFI or UEFI entry was assigned to the device like what is shown in many tutorials regarding UEFI installs. The only constructive information regarding this question is found at  and  but can not work out the answer. Checking md5sum and sha256 checksums on downloaded .iso and used "Check disk for defects" to check burned .iso when booting DVD in BIOS mode. No errors found. "Check disk for defects" will not run (or any other options) when DVD booted in EFI mode. Due to trying different distributions as well as older and newer flavours of Ubuntu all giving similar results in that no options from grub option screen in EFI mode are bootable (if getting that far) as well as spending time searching Ubuntu Forums have come to conclusion the firmware on this system is hardcoded to handle Microsoft EFI files only. After installing Windows EFI mode here is a  and here is a link to a thread i started at  which may be helpful to others building a dual boot system. Installing BIOS mode and using Boot-Repair to install grub-efi is not a complete solution due to the inability of using installation media EFI mode for recovery and maintenance due to the "you need to load kernel first" and "can not read cd/files" errors as described when trying to boot installation media using EFI. Secure Boot is not an issue. Using msinfo32 from windows confirms Secure Boot is not supported on this hardware. How to edit kernel or load kernel for EFI install? = How to EFI install Ubuntu? PLEASE CONSIDER: This is not a dupe!  The linked question that is indicated to having a working answer does not have a working answer to "###How to edit kernel or load kernel for EFI install? = How to EFI install Ubuntu?" therefor the workaround of installing using BIOS then manually install grub-efi without renaming bootloaders which works to get Ubuntu booting using EFI or using boot-repair to do this (and many unnecessary "fixes" if recommended repair is not changed in advanced settings) also works.  This goes some way to confirming hardcoding of firmware is not stopping grub the boot manager seeing the vmlinuz.efi files in /casper on DVD.  I would like an answer to this so would like this question to be reopened.


Does anyone know how to find the radius of convergence of the series $\sum\ z^{n!}$, where $z$ is a complex number?  I tried to use the definition: $$\frac{1}{R}=\limsup\left|\frac{a_{n+1}}{a_{n}}\right|$$ but I wasn't successful.


Why was the Weekly Day of Silence post deleted?

Why was the  deleted?  It was an answer to the question .  The system didn't allow me to vote to undelete -- there was a message saying it had been deleted by a moderator.  Why was no explanation given?    Response to closure:   This question is different from the proposed duplicate and should not be closed. The  was itself closed as a duplicate of .  I'm going to invoke the Transitive Law of Duplicates and explain how my question is different from Question Y.  First, my question is about the deletion of an answer, and Question Y is about the deletion of a question.  Second, when Question Y was deleted, an explanatory comment was provided.  In this case, no explanation was given, and the second part of my questions asks specifically about this.  Third, the target audience for Question Y was volunteer moderators, whereas mine was aimed at any participant feeling frustrated and impotent to make their voice heard.  Lastly, Question Y urged an extended, continuous work stoppage.  I suggested taking off one day per week, to show, through silence, the belief that the conflict can be resolved through transparency and dialogue.  Note, I have not found any clause in the Code of Conduct or the terms of service stating or implying that subscribers agree to visit the site and participate actively with any particular frequency.  I would think that a side benefit to the company of my proposal would be the reduction of traffic one day a week, which could contribute to an easing of tensions, by lightening the workload of the (paid) Community Managers, who have been stretched to the limit, coping with both increased volume on Meta.SE, and reduced volunteer work product.  I do understand that the company needs to be able to turn a profit, so as to be able to continue to host the sites in the network, and maintain and update the software.  There was no intent on my part to damage the company's image or profitability; and I don't believe there was any suggestion of such an intent in my post.  Below is a screenshot of the first half of the post in question.      (If any member of SE staff feels that this is somehow disrespectful or hurtful to the company -- I would just ask, please don't purge the question from the site. Instead, please simply remove the image, if you feel that is necessary.)    Second response to second closure (after the questions was reopened and then closed again):  In the proposed duplicate's answer, Tim wrote     Once you get to the "I'm done talking!" stage, it's probably more forcing than persuading, and that we just can't host.   My question was all about persuading.  It called for transparency and dialogue.   It had nothing to do with forcing.    Another update:  I've gotten kind of lost in the ups and downs of this question's roller coaster history.  But here is a comment.  Tim didn't say they would quash all protest.  In practice SE has not quashed all protest.  You can call my proposal protest if you like.  I think it's more productive to look at what sort of action is being proposed, and how it's being proposed.  The line was drawn in an arbitrary way, even though Tim specifically said they would have to look at where to draw the line on a case by case basis.  I don't see that anything is to be gained by the movement for transparency and dialogue censoring itself.  If management wants to shut down my proposal, let them shut it down.  We do not need to make that decision for management.  Let the question stand, and let the proposal stand.  Let us prepare the ground for management to respond in a meaningful way.  I invite someone to vote to reopen, so that this will show up in the review queue.  (I'm not allowed to re-vote to reopen.)


How to output the values from an array of unknown length in C++

For a programming class, we have to make a procedure that only take in as parameter the pointer for an array: void myprocedure(int * myArray) and then outputs the elements in it. Since I only know how to do so using a for loop,I tried first to calculate the length of the array by using the line sizeof(myArray)/sizeof(int), only to later realize that sizeof(myArray) doesn't give the size of said array, but rather the size of the pointer.  I need a code that would either let me calculate the size of the array from my procedure, or output the elements in the array without having to know how much are there in.


How to cut a mesh into smaller pieces with python?

I have a big terrain object, I'm trying to write a script that cut it in smaller pieces and then I will export the pieces to other formats. This is required by a game engine because the mesh, if not subdivided at export time, is not properly culled, resulting in slow rendering.  I tried to use bpy.ops.view3d.select_border() but it fails with message:  RuntimeError: Operator bpy.ops.view3d.select_border.poll() expected a view3d region   A search revealed that select_border must be called from 3d view, probably by clicking a button. But this is not a generalized script, it is specific to this model, I will rewrite parts of it if I need it for another model. I want to run it from text editor directly.  The only solution I can see for now is to iterate every vertex of the selected object and if they are inside the defined tile size, then duplicate, separate, export, delete, and repeat moving one tile to the left, starting at object dimensions[0] / 2 * -1, dimensions[1] / 2 * -1. Iterate vertices and select them can be done from text editor.  Is there a more convenient way of doing this?


Is there an elementary explanation of why the row-rank of a matrix equals its column-rank (without using adjoint maps, resp. lots of technical computations)? What is the geometric intuition behind this?


mySQL passing a variable as cells name does not results in cells content

To query in different cells of a given table I want to use one function where I pass the cell´s name to query, like this :  $cell = 'frames';  $query = $this->db->prepare('SELECT :cell FROM time_table WHERE time = :time '); $query->bindValue(':cell', trim($cell), PDO::PARAM_STR); $query->bindValue(':time', trim($time), PDO::PARAM_STR); $success = $query->execute(); $query_result = $query->fetchAll();   print_r($query_result);   But instead of getting the content of the frames I get the cell' name, which is frames.  What do I need to do to get the content ?


Coupon collector's problem: mean and variance in number of coupons to be collected to complete a set (unequal probabilities)

There are $n$ coupons in a collection. A collector has the ability to purchase a coupon, but can't choose the coupon he purchases. Instead, the coupon is revealed to be coupon $i$ with probability $p_i=\frac 1 n$. Let $N$ be the number of coupons he'll need to collect before he has at least one coupon of each type. Find the expected value and variance of $N$. Bonus: generalize to the case where the probability of collecting the $j$th coupon is $p_j$ with $\sum\limits_{j=1}^n p_j=1$  I recently came across this problem and came up with/ unearthed various methods to solve it. I'm intending this page as a wiki with various solutions. I'll be posting all the solutions I'm aware of (4 so far) over time.    EDIT: As mentioned in the comments, this question is different from the one people are saying it is a duplicate of since (for one thing) it includes an expression for the variance and it covers the general case where all coupons have unequal probabilities. The case of calculating the variance for the general case of coupons having unequal probabilities has not been covered anywhere on the site apart from , which this one intends to consolidate along with other approaches to solve this problem.    EDIT: Paper on the solutions on this page submitted to ArXiv:


Earlier I had asked a question about the series: $$ \sum_{n=1}^{\infty} \sum_{m=1}^\infty \frac{1}{{n^2 +m^2}}. $$ Which looks like some kind of double series version of the Basel problem.  Much to my disappointment this series was shown to diverge here ().  There could still be a series worthy of being called the Double Basel Problem. $$ \sum_{n=1}^{\infty} \sum_{m=1}^\infty \frac{1}{{(n^2 +m^2)^2}}. $$ This double series is certainly convergent; however evaluating the sum involves tackling some series I have never seen before.   Using the same kind of trick from the other problem and differentiating, this double series can be reduced into: $$ \sum_{n=1}^{\infty} \frac{\pi^2}{4n^2} {csch}^2\pi n + \frac{\pi}{4n^3} \coth \pi n - \frac{1}{2n^4} $$ Has anyone seen series like the first two? How do we even begin to make progress on this kind of thing? Thanks for all of your help!


I need to solve $3x^2 + 6x +1 \equiv 0 \pmod {19}$  I saw the same problem here -     but didn't understand how he got to the conclusion   $x(x+2) \equiv 6 \pmod {19}$  and anyway im trying to solve it how we learned in class -   multiply both sides and the modulo by $4a$ then solve the two equations  $y^2 \equiv b^2 -4ac \pmod {4an}$  $2ax + b \equiv y \pmod {4an}$  so I tried multiplying the hole thing by $4a$ , that is $4 \times 3$  and got to $(2 \times 3x + 6)^2 \equiv 36 -4 \times 3 \pmod {19 \times 4 \times 3}$  now I am stuck . any help will be appreciated


Can't post feedback, but can post answers; or, how to address a problem with an existing answer?

I just created an SO account to offer some feedback to .  Although I can apparently post a whole answer, or even edit others' answers (okay, it's moderated, but still), I can't post feedback to the one answer on that page I wanted to.  I don't have anything to add further to the other answers already posted, but I wanted to post a likely explanation as to why the poster of the linked answer didn't get a flush.  (The calls to flush and close lack parens, so all you get is a reference to the function, not an invocation of it.)  The tips popup for the answers makes it clear that answers should answer the OP, not address other answers.  I don't want to edit the answer at hand (even if it would be accepted), because it's not my post.  Can I do anything, or should I wait until I've built up enough reputation?


Have you previously applied to enter or remain in canada? What should I put?

I was applied for a permanent residence visa for canada, they declined on 2005. In 2012 I entered in canada with swazi passport (while allow port entry). Now I am applying for a visit visa with swazi passport.   So what should I put yes or no?  If yes what should I write. Ex. In 2012 i enterd in canada but I didnt apply for remain in canada.


Which is correct: "Who is Greek president" or "Who is the Greek president"?

I saw this in  on Stuff.  Who is Greek president?  Jose Barroso Karolos Papoulias Lucas Papademos Panagiotis Pikrammenos  (sic)  Surely the word "the" should be in there somewhere?  But I've heard, for example, "US President Barack Obama" used instead of "the US President Barack Obama", so I'm curious if this construct is actually valid.


I wanted to know how I can grab numbers out of a string in C++.  I'm getting the string from an input and will be getting multiple lines, but I already have the line reading working. Note: the lines always have an even number of ints  Here's what I'd like the code to look something like:  std::getline(std::cin, line);// line looks something like "10 3 40 45 8 12" int a, b; while(!line.empty() /*line still has ints to extract*/) {     a = someMethod(line);//gets first int.  So, 10 first loop, 40 second, 8 third     b = someMethod(line);//gets second int. So, 3 first loop, 45 second, 12 third     myMethod(a,b);//a method from elsewhere in my code.  It's here so you know that I need both a and b }   Anything similar would help. Thank you very much!


I have a problem. I'm trying to render an image and the resolution is 500x280. After I render the image and save it, for some reason the image gets resized to 250x140. I'm unsure why it happends.


Locking of questions is currently in place, and is typically used in cases like halting edit wars. However, instead of locking an entire question and its answers, I think that it would also be beneficial to able to lock individual answers, leaving the question and other answers still active.  Some reasons why I think it would be useful:   If an answer falls prey to an edit war: Admittedly, I haven't actually seen this happen for an answer, just questions. But locking only the answer would be a helpful option in such a case. For specific use on MetaSO: There are a number of questions on MetaSO that have the form where the question is simply a container for a general class of feature request, with the answers representing the specific individual feature requests that are accepted or declined. For example, . Some of the retagging suggestions in the answers have been completed, and these are indicated with a "DONE" icon placed at the top (example ). However, the answer can still be edited, voted on, and commented on, which isn't really of any use now that the request has been filled. The answer could be deleted, but then there's no record of previously suggested and accepted requests. It would be nicer if the answer alone could be locked, freezing the editing, voting, and commenting so that it can simply remain there for posterity.   So, what's the community's take? Is this a useful/feasible feature request?    EDIT: As Kyle so adeptly pointed out with his answer, this feature is already enabled. In short, you pretty much can't do anything to a locked answer... unless you're a mod, in which case you can unlock it.  As a summary, here's what you can't do to locked answers:   Edit Up/downvote Flag Mark as accepted (I was kinda surprised by this one) Comment Upvote comments Flag comments


how refraction takes place at atomic level?

when light beam is incidented at some angle on the surface of a medium some part of the light is reflected and some refracted. I want to know about refraction. As the photons interact with the atom and get reemitted in all the directions, how the photons know to a particular angle they should refract?


I am studying 7th and I am having hard time with this problem. Need help. How to find the value of B in the following equation? A=B^e mod C Thanks in advance :-)


Where did the idea of genetic memory originate?

Recently I started re-watching (/playing in the background whilst I work) the Sci-Fi series Andromeda.   In the first series I come to an episode with a familiar sounding premise. The heroes arrive on a planet inhabited by people who pass on memories through the generations. That is, if you have a kid, that kid remembers everything that you remember up to the point it was conceived.  Now, Andromeda is an old series, it's from the turn of the millennium. But this sounds awfully familiar to me.... Assassin's Creed much?  The entire premise of the Assassin's Creed games is based on the idea that locked within our genetic code is the memories of our ancestors and with a special machine these can be unlocked and explored.  It strikes me that an idea such as this cannot possibly have came from an episode of a low budget early 2000s science fiction show. That Andromeda and Assassin's Creed must be taking their influence from earlier works.  Does anyone know where this idea originates? Are there any other prominent examples of it in practice?


Python Exception instances can be indexed directly

I just discovered that a python exception can be indexed directly very similarly to a Sequence type object, like so:  >>> e = Exception('msg') >>> print e[0] msg >>> e = Exception(1,2,3) >>> x,y,z = e   It looks like BaseException contains methods for example __getitem__ and __getslice__ that implement this syntax.  However, what surprise me is that I can not find any relevant description about this behavior in the documentations I can think of looking into, e.g., related sections of  and .  Is this a documented syntax and where is it documented?


new to blender, but eager to learn, and spending lots of time with blender now. I am trying to make a simple solar animation in Blender 2.79, Cycles engine.  The earth spins around the sun's (scene's) Z axix, but earth also has a constant tilt of 23.4 degrees to the sun. I need to keep this earth tilt constant and make the earth spin around it's own Z axis.  I cannot figure out how shift the earth-mesh-objects coordinates. Even if I set the transformation orientation to Local, the earth still spins around the global scene's Z axis when I try to animate or rotate the Z axis of the earth.  I have googled and searched but cannot find an answer.  BTW! I don't want to change the angle of the sun to the earth to achieve the same effect. I also suppose I could manually apply rotations to all axis of the earth to simulate this, but this complicates things as I also have other objects I need to apply this to.  Any tips on how to separate the earths axis from the scene and being able to apply separate/local rotations? As you see in the attached picture the sun and the earth mesh has different axis, but still, when trying to animate the earth it rotates around the scene/suns axis and shifts the poles of the earth around.


Validation Error less than training error?

I found two questions  and  about this issue but there is no obvious answer or explanation yet.I enforce the same problem where the validation error is less than training error in my Convolution Neural Network. What does that mean?


Why is $|e^{i \lambda z}| |e^{- \lambda y}|= |e^{- \lambda y}|$ here?

Let $z \in \Gamma (R)$ where this is the upper semi circle centred at the origin with radius $R>1$. Let $z=x+iy$ with $x \in \mathbb{R}$ and $y \geq 0$. So   $$|e^{i \lambda z}|=|e^{i \lambda z}| |e^{- \lambda y}|= |e^{- \lambda y}|$$  where $\lambda \in \mathbb{R}^{+}$.  How can the last equality possibly be true?


I'm new to salesforce and I have to parse  JSON and store the values in variables. I have used json2apex which generated 2 classes for me. When I use system.debug I can see it's reading the JSON object, however I have no idea how to store this many variables it in List<> format I used this line to store them but it does not work: for(Meals m: retrievedMeals){ mealData.add(m.meals[]); } Can somebody please give me help me to store these values? public class Meals { @AuraEnabled public List<Meals> meals;  @AuraEnabled public String idMeal; @AuraEnabled public String strMeal; @AuraEnabled public String strCategory; @AuraEnabled public String strArea; @AuraEnabled public String strInstructions; @AuraEnabled public String strMealThumb;  public static Meals parse(String json) { return (Meals) System.JSON.deserialize(json, Meals.class);     } }   public with sharing class MealsRetriever { private static final String MEAL_URL = 'https://www.themealdb.com/api/json/v1/1/search.php?s='; private static final String GET = 'GET';  public static List<Meals> getMealData(){      List<Meals> mealData = new List<Meals>();      Http httpCallout = new Http();     HttpRequest req = new HttpRequest();     req.setEndpoint(MEAL_URL);     req.setMethod(GET);      HttpResponse mealResponse = httpCallout.send(req);     Meals mealParseResponse = Meals.parse(mealResponse.getBody());     List<Meals> retrievedMeals = mealParseResponse.meals;          /*this is the part where i try to store the values, but I dont know how     for(Meals m: retrievedMeals){        //Meals.idMeals = retrievedMeals.get('idMeal');     }       return mealData;     } }


Triangle Inequality for norm integral $\|f\|_1=(\int_a^b [|f|^2+|f'|^2]\mathsf dx)^{1/2}$.

Define $C_1^1[a,b]$ to be the space of continuously differentiable functions on $[a,b]$, with norm $$\|f\|_1=\left(\int_a^b[|f|^2+|f'|^2]\mathsf dx\right)^{1/2}.$$ Show that this is a proper definition of a norm. Is this normed space complete?  I'm stuck on the triangle inequality part. I'm having a hard time showing that $$\|f+g\|_1\leq \|f\|_1+\|g\|_1.$$ Any hints or solutions are greatly appreciated.


What Ubuntu version should I use? Here are the specs.   Intel Celeron 2.80Ghz Processor LGA775 socket motherboard (Asus P5PE-VM) 2GB RAM 80GB Hard Drive Intel 865G + Intel ICH5 Chipset Intel Extreme Graphics 2   Thanks in advance Bombet


How to open a PDF form file that says Please wait...?

When I try to open  it looks this way (I have tried Evince, Chrome and Firefox), saying     Please wait...      If this message is not eventually replaced by the proper contents of the document, your PDF viewer may not be able to display this type of document.      You can upgrade to the latest version of Adobe Reader for Windows®, Mac, or Linux® by visiting .      For more assistance with Adobe Reader visit .     I have found  saying     Certain PDF files (dynamic XFA forms) created in Adobe LiveCycle can only be opened in Adobe Reader and Adobe Acrobat. When you try to open these files in an alternative PDF viewer, then you will see this error message.   How are such files meant to be opened on Ubuntu given the official Adobe Acrobat Reader package is deprecated?  It's not a real problem for me practically as I have actually managed to install Adobe Acrobat Reader 9 (BTW I am, however, afraid this ancient version is going to start having problems with opening new files of this kind soon) on Xubuntu 15.10 a reasonably tidy way by unpacking the old Ubuntu DEB package, putting the necessary files to a subdirectory in /opt and editing the Reader's launch scripts but I believe it's a pretty serious issue for using Ubuntu in commercial/academy/government environments so there is to be a more proper way.


Minecraftpocketedition username double § problem

On minecraft PE I accedently typed in two § instead of one § for my username and whenever I try joining a server it says invalid name and I can't change my username! Why?  (This is not a duplicate from the invalid name problem because I typed in §§ it didn't just come up!)


In Git, What is the difference between "remotes/origin/HEAD" and "remotes/origin/master"

>git branch -a * master   remotes/origin/HEAD -> origin/master   remotes/origin/master   Are they both same, if yes then why do we have two.


Proving that $A_1\times A_2 \times \cdots \times A_n$ is countable

If $A_1$,$A_2$,...,$A_n$ are countably infinite sets, is $A_1\times A_2\times...\times A_n$ countable? it seems that an infinite Cartesian product of countable sets may still be uncountable for every x∈[0,1) in a countable set.


I recently came across this issue. I searched online and found that a stranded preposition might be no longer treated as incorrect, but it's just a guess. Are you still taught not to end a sentence with a preposition or is it a myth now?


Can a single molecule have a temperature?

A show on  the weather channel said that as a water molecule ascends in the atmosphere it cools. Does it make sense to talk about the temperature of a single molecule?


I frequently use ccleaner to (cover my tracks), clean up unused data stored on my computer from web traffic and hotfixes on my windows system.  I was wondering if there is a piece of software that does the same thing for ubuntu that ccleaner does for windows?  Please and thank you.


PHP: what are the diff between goto and another control structures like while

I checked the opcodes of an application and noticed that the goto command performs the JMP operation. However, some structures such as if, while, and for also use the JMP like goto.  The questions are: 1. Why shouldn’t we use goto? 2. Has the goto command been deprecated in PHP? 3. what's the meaning of Dinosaur in this picture?


Let $R$ a commutative ring and $M$ a $R$-module. Prove there is a bijection between the set of $R[x]$-module structures on $M$ and $\mathrm{End}_{R-\mathsf{Mod}}(M)$.  I really don't even know how to start with this question.


email regex not working properly with javascript/angular

I have created a regular expression for email validations. var regex = "^([a-zA-Z]+([\.-_]?[a-zA-z0-9]+)*)\@([a-zA-Z0-9]+)([-][0-9a-z]+)?\.([a-z-]{2,20})(\.[a-z]{2,3})?$" To match emails: 1. update@update  2. mohit.bhagat@B-9com.com 3. mohit.Bhagat@us.thalesgroup.com 4. mohit@gmail.com.com.com  If you run this over online  1 and 4th will fail while 2, 3 will pass. But when I run this code in Javascript( Browser console ), 1st also passes the validation. I am using Angular application.


Why is this error happening? I'm using freemarker-2.3.20 and spring-webmvc-3.2.17   Caused by: java.lang.NoSuchMethodError: freemarker.template.Configuration.<init>(Lfreemarker/template/Version;)V         at org.springframework.ui.freemarker.FreeMarkerConfigurationFactory.newConfiguration(FreeMarkerConfigurationFactory.java:320)         at org.springframework.ui.freemarker.FreeMarkerConfigurationFactory.createConfiguration(FreeMarkerConfigurationFactory.java:250)         at org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer.afterPropertiesSet(FreeMarkerConfigurer.java:114)         at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)         at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)         ... 58 more


Bottom to top explanation of the Mahalanobis distance?

I'm studying pattern recognition and statistics and almost every book I open on the subject I bump into the concept of Mahalanobis distance. The books give sort of intuitive explanations, but still not good enough ones for me to actually really understand what is going on. If someone would ask me "What is the Mahalanobis distance?" I could only answer: "It's this nice thing, which measures distance of some kind" :)   The definitions usually also contain eigenvectors and eigenvalues, which I have a little trouble connecting to the Mahalanobis distance. I understand the definition of eigenvectors and eigenvalues, but how are they related to the Mahalanobis distance? Does it have something to do with changing the base in Linear Algebra etc.?  I have also read these former questions on the subject:       I have also read .  The answers are good and pictures nice, but still I don't really get it...I have an idea but it's still in the dark. Can someone give a "How would you explain it to your grandma"-explanation so that I could finally wrap this up and never again wonder what the heck is a Mahalanobis distance? :) Where does it come from, what, why?   UPDATE:   Here is something which helps understanding the Mahalanobis formula:


Using query to populate JList using the DefaultListModel

I am a Java novice building a multiple Frame TabbedPane application with multiple panels.  On one of my one of panels I am using a JList and attempting to populate it using a query.  I am using SQLite as the DB.  private JList<String> listTTSearch;  public void loadList() {     try {         String query = "select tt_name from TriTiers";         PreparedStatement pst = dbConn.prepareStatement(query);         ResultSet rs = pst.executeQuery();         DefaultListModel<String> DLM = new DefaultListModel<String>();          while(rs.next()){             DLM.addElement(rs.getString("tt_name"));         }         listTTSearch.setModel(DLM);         pst.close();         rs.close();      } catch (Exception refreshTable) {      } }   No errors are thrown and the JList, listTTSearch is not being populated. Other aspects of my application are working well with the DB.  A similar posts seems to address this issue , but does not seem to plausible to fix my issue.  Any assistance or guidance would be greatly appreciated.


How can I escape apostrophes in my SQL statement?

Not to get into a discussion about SQL injection and sanitizing and etc...  For various reasons, I am doing the unspeakable and building and executing a dynamic SQL query WITHOUT using query params.  So... I'm building a list of columns and a list of values, and then I have the following code:  insertRecord.setSql("INSERT INTO MyTable(" & columns & ") VALUES(" & values & ")");   This works properly for most records, but for a few records one of the string field values has an apostrophe or single quote:  'SHERIFF'S OFFICE'   This is giving me the SQL error: Incorrect syntax near 'S'.  I have tried using preserve single quotes in several ways and it doesn't help:  insertRecord.setSql("INSERT INTO MyTable(" & columns & ") VALUES(" & preserveSingleQuotes(values) & ")");   OR  insertRecord.setSql(PreserveSingleQuotes("INSERT INTO MyTable(" & columns & ") VALUES(" & values & ")"));   Is there any way to escape all the apostrophes, or otherwise format my sql string properly, other than using a ReplaceNoCase(colValue, "'", "''") on each value individually as I'm building the string (which does work)?


how much of a difference does bike weight make when trying to maximize the bike's top speed?

Today I was at a bike shop looking at single speed bikes. I rode one, but didn't buy it because I like to bike fast, and this bike must have weighed 2x more than my aluminum road bike (the bike was steel).  The store owner told me that the bike weight will not have as great of an effect on my top speed as many other things both on the bike and things I could change about how I ride.  Is he right or wrong? Does bike weight make a big difference or is it just very good marketing?


Can stationary time series contain regulary cycles and periods with different fluctuations

I just started trying to undestand the notion of stationary in time series. Basically I have 2 questions:  Can stationary time series contain regulary cycles and thus seasonality patterns? For exmaple in this tutorial it is stated that stationary time series can not have seasonal components (predicitable cycles)  whereas in this figures () the green time series that clearly has cycles (and thus seasonality) is labeled as 'stationary' (and I have seen these kind of figures quite often if you just google 'stationary time series) Can a stationary time series have periods with no fluctuations and periods with high fluctuations? As far as I understood the variance and the (aut)covarianz should not change over time making such a time series not stationary. But here in this picture () the time series below is labeld as stationary altough it has periods with changing fluctuations.  I hope you can help me as I am confused about the concept of stationarity. I'd appreciate every comment. The bounty is to expire quite soon. So I'd be happy if some could at least give me one answer to my questions. It will help me a lot. Why is nobody answering the questions? Are they not clear enough? If so, please tell me. I think they are important and fundamental as the concept of stationarity is quite important.


Whose answer should you accept: Another person's or your own?

I asked a question about a programming problem and someone wrote a couple of comments, trying to help me find the source of the problem and even pointing out a problem with my code that was easy to fix (but that wasn't the problem I originally asked the question for).  Eventually that other person suggested a different way of doing what I was trying to do but I ended up fixing the problem within my original code myself. Afterwards I asked the other person to post his suggestion as an answer, which I already upvoted (because it works too) and I'm also going to post an answer explaning how to fix my original code with the solution I found.  Now I'm not sure what to do with those two answers: My answer fixes the code and solves the problem but the other guy's answer works too and he suggested the alternative way of doing it before I was able to fix the code myself.  Which answer do you accept in that case? The answer that came first or the answer that stays true to the original code?


Attaching a rope (curve or mesh) to two other objects

I've already read two threads on this but the instructions given are not clear enough for me.  i would like to attach the ends of the highlighted mesh, so that animating this part isnt so tedious.


If dark matter only interacts with gravity, why doesn't it all clump together in a single point?

I'm a complete layperson. As I understand, dark matter theoretically only interacts with the gravitational force, and doesn't interact with the other three fundamental forces: weak nuclear force, strong nuclear force, and electromagnetism.  Those are my understandings going in. If I'm wrong, please correct me. I've done some googling, and I haven't found anything confirming or denying that dark matter is affected by either of the fundamental nuclear forces.  So since dark matter only interacts with gravity, what causes any dark matter particle to be repelled from another? If they can pass freely through each other, and they are gravitationaly attracted to each other, why don't such particles clump together in a single 'point' in space?   It seems to me that particles occupying a single 'space' are philosophically not distinct particles, but I don't know how actual physics would play into this.  Edit , author's credentials unknown, but implicitly claims to be a physicist or astronomer, says "...[P]hysicists generally take all dark matter to be composed of a single type of particle that essentially interacts only through gravity."  Edit 2 The author is this , "Professor of Science on the physics faculty of Harvard University."


When to use the gerund form of a verb after "to"?

I would like to understand when to use the gerund form of a verb after "to." I had in my mind that every verb used after "to" was in its infinitive form, like for example:   It is hard to play the piano when your fingers are cold. Call me if you decide to buy those pants.   However, I have come across sentences where this logic is not followed; for example:   I got used to reading in the bus. He went back to studying mathematics.   This is getting me very confused, so I need some help with this.


Free API or database for Continent, country, city, region/state?

Is there a database or API that can provide: Continent, country, city and region/state? It should also have the country codes in ISO format. It would also be great if if could all be in one file for easy access. Ideally, the API/database shouldn't have too many fields as I would prefer concise data. It would be a good bonus if it included support for different languages.  I found that GeoNames contains too many places and landmarks. Same with Yahoo GeoPlanet. GeoDataSource is too scattered between different files. I prefer something that is not too big and concise and possibly with an hierarchical structure.    Actually I found one here!!!!


Lat/Long co-ordinates are not plotting onto EPSG:3857 OSM basemap correctly

Excuse me if this is a stupid question, but I've honestly tried to find the answer in a few threads here on SE, and I cannot seem to follow the suggested steps correctly.    Project is in  (WGS 84 / Pseudo-Mercator) BaseMap (OpenStreetMap) layer is set to EPSG:3857 Vector data has been imported from CSV, and has Lat/Long coordinates, set to EPSG:3857.    The layer appears right in the middle of the map, around 0,0 obviously.   Why is this, what am I doing wrong?


Helping understanding finding a limit without L'hopital's rule?

$\lim \limits_{x \to 0}x\sin\left(\frac{1}{x}\right)$   I need to find and prove this limit.  I can easily plug it into wolfram alpha, but I want to make sure I learn something.  It's been 3 years since my Calculus 2 course and I just cannot remember how to tackle this one.  Hints?


What exactly are the differences between "diligent", "assiduous" and "sedulous"?

From :   (formal) showing great care and effort in your work synonym: diligent  (formal) working very hard and taking great care that everything is done as well as it can be synonym: diligent  (formal) showing care and effort in your work or duties  These definitions look alike. What they have in common is that these words mean to take care and to put effort into your work. All words are formal. None of these seems to be a proper term in a specific field, e.g. medical, law. I also looked at  to get more details. This adds the connotation of steady and earnest to diligent and unremitting attention and persistent application to assiduous. But in the end, these additional information are again describing an equal thing, i.e., continuously doing your work. The entry on sedulous doesn't add any more content; it refers to diligent and again describes the word with perseverance. From this point (checking dictionaries only), I don't see any difference at all. I continued with a corpora search. From : Diligent is most used in combination with work, effort, research, study but also student, people.  She's a diligent student. His diligent research identified the value of ...  Assiduous is also most used with work, effort, research but not with student, people. Merriam-Webster's Learner's Dictionary entry on  lists student as example though.  He's assiduous in his work. With assiduous attention to detail ...  Sedulous is most used, um, to little results.  has even less content. Merriam-Webster's example is, once again, a student. So, diligent is used most often, followed by assiduous and sedulous is quite rare. All words are formal. All words seem to be usable as an attribute to a person (e.g., student) but also specifying the intense care and effort on work, e.g., a research. I don't see any significant difference in these words, besides frequency. When is a student diligent, assiduous or sedulous? And when is a research diligent, assiduous or sedulous? Or simply: What are the subtle distinctions which aren't represented by dictionaries?


Seeking a combinatorial proof $\sum _{k=0}^{2n} (-1)^k \binom{4n-2k}{2n-k}\binom{2k}{k}=\binom{2n}{n}\times 2^{2n}$

I would appreciate if somebody could help me with the following problem  Q: Seeking a combinatorial proof $(\binom{n}{k}=\frac{n!}{k! (n-k)!} )$  $$\sum _{k=0}^{2n} (-1)^k \binom{4n-2k}{2n-k}\binom{2k}{k}=\binom{2n}{n}\times  2^{2n}$$


Countdown timer to logout of application

I have developed a staff record system for my company. The problem im facing is that the staff leaves their systems logged on and even forget to logout. I want the system to logout the user after leaving the system idle for 10 minutes. I have virtually no idea on how to go about it. I need your help


I had installed Ubuntu 13 10 my ethernet is working fine. But when I want to connect with my Wi-Fi it ask me a key after entering the key it again ask me for the key but its not connecting to my Wi-Fi network.


I've already see a  by Marko Riedel which I list it follows:     The standard way to treat these sums is to integrate   $$ f(z) = \frac{1}{(z+\alpha)^2} \pi \cot(\pi z)$$   along a contour consisting of a circle of radius $R$ and with $R$ going to infinity and hence being larger than $\alpha$, where the circle does not pass through the poles on the real axis.   Now along the semicircle in the upper half plane we have   $$|f(z)| \le \frac{1}{(R-|\alpha|)^2}\pi \left|\frac{e^{i\pi R\exp(i\theta)} + e^{-i\pi R\exp(i\theta)}} {e^{i\pi R\exp(i\theta)} - e^{-i\pi R\exp(i\theta)}}\right|= \frac{1}{(R-|\alpha|)^2} \pi  \left|\frac{e^{2i\pi R\exp(i\theta)}+1}{e^{2i\pi R\exp(i\theta)}-1}\right| < \frac{1}{(R-|\alpha|)^2} \pi   \frac{1+e^{-2\pi R\sin(\theta)}e^{2i\pi R\cos(\theta)}} {1-e^{-2\pi R\sin(\theta)}e^{2i\pi R\cos(\theta)}}$$   This last term is clearly $O(1/R^2)$ as $R$ goes to infinity as the quotient of the two exponentials goes to one since $\exp(-R)$ vanishes and there is no singularity when $\theta = 0$ or $\theta = \pi$ as $R\cos\theta = \pm R$, which is not an integer by the assumption that the circle avoids the poles and hence cannot be one.     My question: It is clear that for each $z=Re^{i \theta}$ , $f(z)=O(1/R^2)$ ，but can this guarantee that the last term on RHS is uniform bounded ? Since $\theta$ varies on a compact interval $[0, \pi]$ , I want to show that for each $ \theta \in [0, \pi]$ , and a fixed positive number $M \gt 1 $ there exist an open ball contains $\theta$ and a fixed $R_{\theta}\gt 0$ , for every $R \ge R_{\theta}$ and $x \in $ the open ball $$\frac{1+e^{-2\pi R\sin(x)}e^{2i\pi R\cos(x)}} {1-e^{-2\pi R\sin(x)}e^{2i\pi R\cos(x)}} \le M$$  For $\theta \neq 0,\pi$ , it is easy to find the desired $R_{\theta}$ and the open ball , but if $\theta = 0$ or $ \theta = \pi$ , for every open ball containing $\theta$ , it behave erratically near $\theta$ , I have no idea how to deal with this .


converting a javascript string to a html object

can I convert a string to a html object? like:  string s = '

'; var htmlObject = s.toHtmlObject;   so that i can later on get it by id and do some changing in its style  var ho = document.getElementById("myDiv").style.marginTop = something;   Thanx a million in advance, Lina


I recently updated the Ubuntu OS and now I cannot get the Java programs to connect to the MySQL database. The following error occurs: java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:3306/PTAX?useSSL=false  I searched the web and the only thing I found was to install libmysql-java. However, when I try to install it, the message below occurs. Unable to locate package libmysql-java


Proving the following inequality without using AM-GM inequality.

Let $x,y,z \in \Bbb R^+$ such that $x+y+z=3$. Prove the inequality   $\sqrt x+\sqrt y+\sqrt z \ge xy+yz+zx$     I tried to prove that $\sqrt x+\sqrt y+\sqrt z-(xy+yz+zx)\ge 0$ I squared the equality, put the value of $xy+yz+zx$ (in terms of $x^2+y^2+z^2$). Now I tried to prove that the above expression but failed.    Thanks for hints or solutions.


HashMap: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.HashMap.put'

I've initialized HashMap#onCreate method and i want to use HashMap in addLocation method. Everything looks okay but I don't understand why I get this error:  java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.HashMap.put(java.lang.Object, java.lang.Object)' on a null object reference   when I call locationList#put method.  Here's my code:  public class InitLocationsOnStartup extends Application implements LocationListener {     HashMap < String, Double[] > locationList;     List < StationViewModel > stations;      @Override     public void onCreate() {         super.onCreate();         stations = new ArrayList < StationViewModel > ();         locationList = new HashMap < > (); //      }      public void getStations(List < StationViewModel > list) {         this.stations = list;         addLocation(locationList);     }      public HashMap < String, Double[] > addLocation(HashMap < String, Double[] > locationList) {         for (int i = 0; i < stations.size(); i++) {             latLong = new Double[] {                 Double.parseDouble(stations.get(i).getLatitude()),                     Double.parseDouble(stations.get(i).getLongitude())             };              if (stations.get(i).getStationName() != null && latLong != null) {                 locationList.put(stations.get(i).getStationName(), latLong);              }         }         return locationList;;     }


According to HTML specs, the select tag in HTML doesn't have a readonly attribute, only a disabled attribute. So if you want to keep the user from changing the dropdown, you have to use disabled.  The only problem is that disabled HTML form inputs don't get included in the POST / GET data.  What's the best way to emulate the readonly attribute for a select tag, and still get the POST data?


Using Android app 1.0.59  The button to see revisions seems to be broken in the Android app. The app does nothing when I click the "Edited " words (which should bring me to a page with revisions).  My internet connection is perfect.  The app is not lagging.  Is it possible to fix this bug?


In the manual page of tar command, an option for following hard links is listed.  -h, --dereference       follow symlinks; archive and dump the files they point to  --hard-dereference       follow hard links; archive and dump the files they refer to   How does tar know that a file is a hard link? How does it follow it?  What if I don't choose this option? How does it not hard-dereference?


Situations where "Without Loss of Generality" expressions can be used.

I am trying to understand in what situations mathematicians use the expression "without loss of generality". The  states that the expression is useful in symmetric situations such as if we assume two outcomes $a$ or $b$, then we can assign a symbolic math where we can make assumptions such as assume $a>b$, so in such scenario we don't loose any generality as we can equally say assume $b>a$, because symbols are symmetric and can be used interchangeably. Is this the correct understanding of the expression?


No secondary button (right click) on touchpad

I'm experiencing a serious problem with the new Ubuntu 18.04:  System Dell XPS 13 with a freshly installed Ubuntu 18.04 LTS.  Problem description The touchpad provides only primary button (single click and double click), but no secondary button. In particular, when using the "test Your Settings" option in Settings -> Devices -> Mouse & Touchpad, any click on the touchpad is signaled as primary button, no matter where I click (left or right side of the touchpad). This remains the case even after I change the Primary Button from Left to Right (in Settings -> Devices -> Mouse & Touchpad -> General).  In comparison, an external mouse connected to my laptop (via usb) works fine: it provides both primary and secondary buttons with sides corresponding to the choice of Primary Button (in Settings -> Devices -> Mouse & Touchpad -> General).  This may be related to   Any ideas?  Update: Meanwhile, I found out that in addition to the solution proposed by EntropyWins, one can also control this touchpad behavior via the Tweaks tool (a.k.a. gnome-tweaks) under Keyboard & Mouse -> Touchpad -> Mouse Click Emulation. In any case, as EntropyWins explains in his answer, this is not a bug.


Are tripods same for all cameras. I am buying my first good camera Nikon D3300 with Nikkor 55-200 VR II, AF-S

I am beginning to learn photography and am buying my first hardware. I have boiled down to Nikon D3300 with Nikkor 55-200mm lens. I am also looking for a tripod because I guess one needs a stable hand to take good shots using a lens. So the question is: Are all tripods suitable for all cameras or there is a specific tripod for each brand?   In any case what tripod should I use? I live at the edge of a forest (I am not allowed to go inside without permission). But wild peacocks and deer do venture out. I wish to capture them (in my camera) but cannot carry the camera the whole day in my hands.  Can I use the same tripod with binoculars?  This question is partly answered in another place but I asking as to how to decide which tripod is more suitable for my requirement of capturing scenery and wild animals. Are there different tripods good for different requirements?


The names of summer months: With or without "the"

This question is the last one for today :)  There is a sentence: "What are the names of (the) summer months?"  Is the article "the" necessary here, before "summer months"? Can the zero article be used here? The question means not specific summer months, but all of them - June, July, August.  Many thanks!


Is it possible to add line breaks in comments?

I've read through the comment formatting section on the .  Adding line breaks to comments doesn't appear to be mentioned, and practice also leads me to believe that line breaks in comments are not possible.  But just in case I'm missing something:  is it possible to add line breaks to comments?


Ubuntu PXE installation is not asking for the hostname or domain

I'm using a PXE server for installing systems in my network. I want it to ask for the hostname and domain on every install instead of asigning 'kickseed' everytime. I cannot figure out what is causing this as I've not specified the name anywhere as far as I can tell and the configuration is only slightly adapter from a working one for Debian Wheezy. I've already seen the other questions on here that were similar, but none of the solutions seemed to work/apply to my case (e.g. "netcfg/get_hostname=...").  kernel ubuntu/14.04_server/amd64/linux append vga=normal ks=http://10.150.253.2/install/kickstart.ks initrd=ubuntu/14.04_server/amd64/initrd.gz locale=de_DE netcfg/wireless_wep= netcfg/interface=eth0 preseed/url=http://10.150.253.2/install/ubuntu/14.04_server/amd64/ubuntu.seed keymap=de --   The seed file:  d-i debian-installer/locale string de_DE.UTF-8 d-i debian-installer/language string de d-i debian-installer/country string DE d-i debian-installer/locale string de_DE.UTF-8 d-i languagechooser/language-name-fb select German d-i localechooser/supported-locales en_US.UTF-8 d-i console-setup/ask_detect boolean false d-i keyboard-configuration/layoutcode string de d-i console-setup/layoutcode string de  d-i netcfg/choose_interface select auto d-i netcfg/dhcp_timeout string 60 d-i netcfg/disable_dhcp boolean false d-i netcfg/wireless_wep string d-i hw-detect/load_firmware boolean true  d-i mirror/protocol string ftp d-i mirror/ftp/hostname string <...> d-i mirror/ftp/directory string /ubuntu d-i mirror/ftp/proxy string d-i mirror/ftp/mirror select <...> d-i mirror/suite string trusty d-i mirror/udeb/suite string trusty d-i mirror/udeb/components multiselect main, restricted  d-i clock-setup/utc boolean true d-i time/zone string Europe/Berlin  d-i partman/default_filesystem string btrfs  d-i base-installer/kernel/image string linux-image-generic-lts-utopic  d-i passwd/root-login boolean true d-i passwd/make-user boolean false d-i passwd/root-password-crypted password <...> d-i user-setup/encrypt-home boolean false  d-i apt-setup/restricted boolean true d-i apt-setup/universe boolean true d-i apt-setup/multiverse boolean true d-i apt-setup/services-select multiselect security d-i apt-setup/hostname string <...> d-i apt-setup/directory string /ubuntu apt-mirror-setup apt-setup/partner boolean true  tasksel tasksel/first multiselect standard  d-i pkgsel/include string \         openssh-server \         vim-nox \         ntp \         xinetd  d-i pkgsel/language-packs multiselect de, en d-i pkgsel/update-policy select unattended-upgrades  popularity-contest popularity-contest/participate boolean false  d-i grub-installer/only_debian boolean true d-i grub-installer/with_other_os boolean true  d-i finish-install/reboot_in_progress note  xserver-xorg xserver-xorg/autodetect_monitor boolean true xserver-xorg xserver-xorg/config/monitor/lcd boolean true xserver-xorg xserver-xorg/config/monitor/selection-method \        select medium xserver-xorg xserver-xorg/config/monitor/mode-list \        select 1024x768 @ 60 Hz  d-i preseed/late_command string \         in-target wget http://10.150.253.2/install/ubuntu/14.04_server/amd64/ubuntu_postinst.sh -O /root/postinst.sh; \         in-target /bin/bash /root/postinst.sh; \         in-target rm /root/postinst.sh


Ideal contained in a finite union of prime ideals

Let $I \subset R$ be an ideal and $P_i$  $(i=\{1,...,n\})$ prime ideals with $I\subseteq\bigcup_{i=1}^nP_i$. Prove that then $I$ is contained in one $P_i$.   I don't know how to show this because I don't have any approach.  So I am looking for something to start with or something like a sequence of tips (Since I know this is a large proof)  Thanks in advance!


Does bounty history get migrated along with a question?

I somehow think this is a dupe, so sorry if it is.  My search-fu is turning up empty...  Do migrated questions retain bounty history?  For example, say a question has a bounty set on one site before enough people vote it closed and migrate it.  The bounty expires on the one site, then it gets enough close votes to migrate.  Is it no longer possible to accept that answer on the target site since the bounty on the first site expired?  I know this probably doesn't happen that often on SO, but I've seen it a few times on SF.  Mainly when the OP doesn't want the question migrated....


Why is the determinant useful when finding eigenvectors?

I understand that the eigenvectors of a linear transformation are the vectors that, when transformed, are simply scaled by a factor of the corresponding eigenvalue. Therefore $$ A\vec{x}=\lambda\vec{x}. $$ We can replace the scaling of the vector $\vec{x}$ by $\lambda$ with its equivalent linear transformation, $\lambda I$. Then we can rearrange this equation as follows: $$ A\vec{x}-(\lambda I)\vec{x}=\begin{bmatrix}0\\0\end{bmatrix}\\  (A-\lambda I)\vec{x}=\begin{bmatrix}0\\0\end{bmatrix}\\  $$ For this to be true either $\vec{x}$ must be a zero vector or the transformation $A-\lambda I$ must have $\vec{x}$ in its null-space. The course I'm following says that we can solve for $\lambda$ by finding when the determinant of $A-\lambda I$ is zero, but why does that guarantee that $\vec{x}$ will become the zero vector when transformed by $A-\lambda I$? I understand that for $\vec{x}$ to be an eigenvector this transformation must have a determinant of zero, but I don't see how the inverse can be true; having a determinant of zero doesn't gaurantee that $\vec{x}$ will be transformed into the zero vector. For example, let $$ (A-\lambda I) = \begin{bmatrix}1&2\\0&0\end{bmatrix}, \vec{x}=\begin{bmatrix}1\\1\end{bmatrix} $$ Then, although $\det\begin{bmatrix}1&2\\0&0\end{bmatrix} = 0$, it does not gaurantee $(A-\lambda I)\vec{x}$ to be the zero vector. $$ \begin{bmatrix}1&2\\0&0\end{bmatrix}\begin{bmatrix}1\\1\end{bmatrix}=\begin{bmatrix}3\\0\end{bmatrix}  $$ We can see that the transformation gives us $\begin{bmatrix}3\\0\end{bmatrix}$ and not the zero vector. Why does finding when the determinant of this transformation is equal to zero help us find the eigenvectors? Am I missing something?


$$ \begin{align}x^2&=x+x+\cdots\ (\text{$x$ times})\\ \implies \dfrac{\mathrm d}{\mathrm dx}(x^2)&=\dfrac{\mathrm d}{\mathrm dx}(x)+\dfrac{\mathrm d}{\mathrm dx}(x)+\cdots \ (\text{$x$ times})\\ \implies 2x&=1+ 1+\cdots \ (\text{$x$ times})\\ \implies 2x&= x \\ \implies 2&=1 \end{align}  $$  Which is obviously wrong. So, where am I wrong?


What do the interconnection symbols mean on the MTR (subway) map in Hong Kong?

Looking at this  map in Hong Kong:      I notice they used different interconnection symbols:   ...  What do they mean?


How does a tourist visa from VisaToRussia with Airbnb work?

When applying for a tourist visa via , when it asks me for an address, am I required to specify a hotel or can I directly choose a location from Airbnb?  This differs from other questions as it is specific to how VisaToRussia operates.


As the title states, I was wondering if the droid's name is C3PO or C3P0. R2D2, another droid, has a letter, number, letter, then another number. I was wondering which name is correct. Thanks!


I need to write some phonetic transcription in my article, but the compiler can not run it properly. MWE is below,  \begin{tabular}{|c|c|c|c|}     \hline     Words & Phonetics & Students Pronounced & Source \\     \hline      Language &  /’læƞgwIdʒ/ & /leƞgwIdʒ/   & S1,S2,S4,S5,S6\\     Important&  /Im’pᴐ:tnt/ & /Im’pᴐ:tent/ & S1,S2,S3,S5,S8,S9\\     \hline  \end{tabular}   but compiler replace all non-standard character into a question mark (?). This probably because I copy and paste the text. But when I type by using Cyrillic letter symbols from side panel, my code generates errors.   Language - /’l\cyrae \ng{}gwId\cyrabhdze/ - /’l\cyre \ng{}gwId\cyrabhdze/       resulting in   "error undefined control sequenced".     What does it mean?


How to select a specific row based on another row from same table


How can I move my /home directory to another partition if it's already part of the / partition?

I have a wonderful running Maverick Meerkat install going on right now. I want to move my /home to another partition as per many suggestions.   How can I go about doing this without reinstalling the entire Ubuntu system? Can I simply create the partition with gparted and then change the mount point of /home in fstab to reflect it or is it a bit more difficult?


How do I resolve "error processing archive" when trying to upgrade Ubuntu?

I am trying to do an upgrade on Ubuntu 14.04. I run:  sudo apt-get -u dist-upgrade   When I run that, I get this error:  dpkg: error processing archive /var/cache/apt/archives/linux-image-3.13.0-24-generic_3.13.0-24.47~precise2_amd64.deb (--unpack):   Here's the entire output:  Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following packages will be upgraded:   linux-image-3.13.0-24-generic 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/52.3 MB of archives. After this operation, 155 MB of additional disk space will be used. Do you want to continue? [Y/n] Y (Reading database ... 63480 files and directories currently installed.) Preparing to unpack .../linux-image-3.13.0-24-generic_3.13.0-24.47~precise2_amd64.deb ... Done. Unpacking linux-image-3.13.0-24-generic (3.13.0-24.47~precise2) over (3.13.0-24.46) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.13.0-24-generic_3.13.0-24.47~precise2_amd64.deb (--unpack):  trying to overwrite '/lib/modules/3.13.0-24-generic/kernel/mm/hwpoison-inject.ko', which is also in package linux-image-extra-3.13.0-24-generic 3.13.0-24.46 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.13.0-24-generic /boot/vmlinuz-3.13.0-24-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.13.0-24-generic /boot/vmlinuz-3.13.0-24-generic Errors were encountered while processing:  /var/cache/apt/archives/linux-image-3.13.0-24-generic_3.13.0-24.47~precise2_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   How do I resolve this? Thanks!


I'm talking about this web part. This web part displaying a few posts (description + title).


while read loop not working inside alias

In Bash, the following command echo foo | while read line; do echo $line; done  outputs foo; however, the following alias bar="echo foo | while read line; do echo $line; done" bar  outputs a \n (or empty space). What is causing this difference in behavior?


I am new to android. I am trying to make a navigation drawer with the help   URL.  Everything works perfectly except one thing.  In my activity_home layout, when I try to add a menu(named drawer_view), in design view of this layout, it is displaying a rendering problem.    Its been about a day that I tried on google for the solution but nothing works.  Please help me out for the same.  Here is the activity_home.xml  <android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:id="@+id/drawer_layout"     android:layout_width="match_parent"     android:layout_height="match_parent">     <!-- The main content view -->     <LinearLayout         android:layout_width="match_parent"         android:layout_height="match_parent"         android:orientation="vertical">      <!-- The ActionBar displayed at the top -->     <include         layout="@layout/toolbar"         android:layout_width="match_parent"         android:layout_height="wrap_content" />     <FrameLayout         android:id="@+id/content_frame"         android:layout_width="match_parent"         android:layout_height="match_parent"         />     </LinearLayout>     <android.support.design.widget.NavigationView         android:id="@+id/nvView"         android:layout_width="wrap_content"         android:layout_height="match_parent"         android:layout_gravity="start"         android:background="@android:color/white"         app:menu="@menu/drawer_view"         app:headerLayout="@layout/nav_header"         />  </android.support.v4.widget.DrawerLayout>   Here is the drawer_view.xml  <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android" >      <group android:id="@+id/group_feature"         android:checkableBehavior="single"          >         <item android:id="@+id/first_item"             android:checked="true"             android:icon="@drawable/coc"             android:title="@string/first_name"/>         <item android:id="@+id/second_item"             android:checked="true"             android:icon="@drawable/cricinfo"             android:title="@string/second_name"/>          <item android:id="@+id/third_item"             android:checked="true"             android:icon="@drawable/flipkart"             android:title="@string/third_name"/>      </group>     <group android:id="@+id/group_settings"         android:checkableBehavior="single">         <item android:id="@+id/navdrawer_item_settings"             android:icon="@drawable/setting"             android:title="@string/action_settings"/>      </group> </menu>   Here is my style.xml file  <resources>     <!-- Base application theme. -->     <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">         <item name="colorPrimary">#673AB7</item>         <item name="colorPrimaryDark">#512DA8</item>         <item name="colorAccent">#FF4081</item>      </style>     Here is the nav_header.xml code  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="192dp"     android:background="?attr/colorPrimaryDark"     android:padding="16dp"     android:theme="@style/Base.ThemeOverlay.AppCompat.Dark"     android:orientation="vertical"     android:gravity="bottom">      <TextView         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:text="Header"         android:textColor="@android:color/white"         android:textAppearance="@style/Base.TextAppearance.AppCompat.Body1"/>  </LinearLayout>   Thanks


How to multiply on a calculator which only allows add, subtract and reciprocal

Assume we have a calculator with the following flaw. The only operations can be done by it are $+$ and $-$ and $\dfrac{1}{x}$ i.e. you only can add or subtract two numbers and also calculate the reciprocal but you can't multiply or divide. Using this calculator how can you multiply two numbers?   I twiddled with lots of formulas but I got nowhere. Sorry if  I can't add any further information or idea. I appreciate any solution on this....


Equivalent condition for finite cyclic commutative group

Let $G$ be a finite, commutative group. Is  $$\text{$G$ is cyclic.}$$ equivalent to  $$\text{For each $n$, there are at most $n$ pairwise  different elements of $G$,}$$ $$\text{such that the order of such an element divides $n$.}$$ ?


How does $(a,b)$ where $a,b\in \mathbb{Q}$ form a basis for $\mathbb{R}$?

Well I can't think how the open set $(\sqrt{2},\sqrt{3})$ can be formed from this basis.


Let $f(p/q)=1/q$ if fraction $p/q$ is in lowest terms and $f(x)=0$ for irrational $x$ and when $x=0$. Show it is integrable on $[0,1]$.  My idea: Construct a partition such that $U(p,f)-L(p,f) < \epsilon$. The lower sum should be 0. It suffice to show $U(p,f)< \epsilon$. Consider a interval $[p/q-\delta, p/q+\delta]$. The length and $sup \ f(x)$ of the interval are known.   And I know the number of such interval is finite. However, I do not know how to construct such interval so I do not know how many interval are there exactly.    Edit: As OP, I am the first to vote for close, as well as reopen. The reason for close is that the function is the same as the one in the link. However, the reason for reopen is that the definition of integration is slightly different, and I do not stuck in the same place as the OP in the link. In addition, it seems the answer does not address my question. So, I vote for reopen.


What Star Wars Legends (EU) content has successfully become a part of Disney canon?

As we all know, when Disney took over the galaxy and executed the executive order to rewrite history, the only existing content to still be recognized as canon are the 6 movies, the Clone Wars and the Rebels cartoons.  The entire EU is thus relegated as Legends - non-canon, but certainly not to be ignored as a potential source of inspiration for future content. So, are there anything (people, events, tech, locations, books etc.) that originated in the EU but has successfully remained part of D-canon?  To put it differently, are there any entities which were not originally considered canon by Disney, whose existence were not suggested in any way by what Disney originally considered canon (no appearance, not mentioned, not implied), but we know is part of Disney's canon now? Basically things that were thrown back into the mix. They didn't necessarily need to be from the EU - it can just as easily be whatever George Lucas and his company created that was initially dumped but brought back in again at a later point.


How can I run badblocks and smartctl over SSH, close SSH without interrupting badblocks and smartctl?

I have a server with a hard drive I'd like to test using smartctl (smartmontools) and badblocks. I would use smartctl first, then badblocks.  My question is three parts:   How can I run the commands over SSH so the process won't stop when I close the Terminal? How can I output the badblocks results and the smartctl info to a file? How can I run smartctl and then badblocks will start automatically (when smartctl is finished) without having to SSH again?   Thank you.


How can I draw a line around text, but open on one side?

I'd like to do something similar to \boxed{whatever}, but with the box open one side. Something like the following.  \documentclass{article}  \begin{document}  \[ \overline{\underline{abc |}} \]  \end{document}   which results in the following output (ugly, but conceptually close to what I want):    I suppose there is a simple way to do what I need, but I couldn't find it.


I need a mirrored symbol \Gamma. Is it posible? I can't find this symbol and I do not know a way to mirror the symbol. I use unicode math.


Increasing the maximum number of enumerate environments?

I am using the outlines package to write some outlines, and occasionally four levels are not enough to present my data. I understand that this is a limitation of LaTeX, as you cannot nest more than four levels of enumerate environments. Is there any way to increase this limit? If not, why is the limit exactly four?


I installed ubuntu 13.10 on my laptop but it won't boot into unity just command line and says running in low graphics mode. How do I fix this.  I have an HP 15-g029wm laptop with amd radeon hd 3330 graphics


Making Ubuntu less resource heavy - running slowly for graphic design

I work mostly in graphic design (GIMP) photo processing (in the past Lightroom and now Darktable) and creating and maintaining websites. I'm currently working on a low spec machine: IBM Think Pad R51, HDD 80 Gb, RAM 1x 512 Mb and 1x 256 Mb, Intel® Pentium(R) M processor 1500MHz , Graphics Intel® 852GM/855GM x86/MMX/SSE2 My question is, what is the most appropriate version of Linux to run lighter on the machine when working with the internet, GIMP and Darktable?


After a few updates on Windows and Kubuntu, on Kubuntu I no longer have write and modify access to NTFS drives, can only read NTFS partitions even as root. Systen config: 128GB M.2-SSD drive, 1TB S-ATA-HDD drive. Installed dualboot: Windows 10 Home, Kubuntu GNU/Linux sda           8:0    0 931.5G  0 disk └─sda1        8:1    0 931.5G  0 part /media/User/DataDrive (NTFS) nvme0n1     259:0    0 119.2G  0 disk ├─nvme0n1p1 259:1    0   499M  0 part ├─nvme0n1p2 259:2    0    99M  0 part /boot/efi ├─nvme0n1p3 259:3    0    16M  0 part ├─nvme0n1p4 259:4    0    60G  0 part /media/User/Windows-10-Home (NTFS) └─nvme0n1p5 259:5    0  58.7G  0 part /Kubuntu (XFS)


Generic Handlers (.ashx) intellisense issue on Visual Studio 2010

I am trying to expand and collapse methods and other things on an ashx file like any other code behind file. When I do tools > options > text editor and adding ashx as an extention of visual studio c#, everything seems ok at the beginning. I can expand and collapse the methods also see the properties and methods at the top of the file. But then I lost most of intellisense. I cant reach my userdefined objects and methods.   Similar Issues that I have found did not help me to solve this problem


Styling multiple files on Libre Office Calc

Here's what I do now:   Get CSV file from extrenal source Open it in Calc Apply style (set colors, fonts, etc.) Export as PDF   Is it possible to get rid of step 3? Somehow loading data to already styled document?  Columns on different CSV files are always the same, but rows might have different data.  I am open to other alternatives too.


Question about MySQL triggers performance

I currently have a database that stores some transactions for several users, for example purchasing or selling products is stored as 1 entry in the transactions table. It can also store profits made between transactions (stored in another table called profits).  I also need to store a daily history of purchases, revenues and profits for each user. I have a history table that looks something like this:  user_iduser   date        total_buy  total_sell total_profit     2500    2016-04-02     24555       45121        2566   Right now, the way I keep the history table updated is outside the database side. The application automatically calculates and updates this table everytime the user logs in (after fetching whatever new transactions come from that day) and updates the corresponding totals for that day. The application also runs a script everyday at midnight that fetches every user's transactions and updates their totals for the previous day. However, I would prefer if this behavior was done by the database instead if possible (the less code the better).  So my question is: would creating triggers be a good way to do this, performance wise? It would be simple to create a trigger that, for example updates a user's history.total_buy column everytime a new 'buy' transaction is inserted, but considering I have several million transactions already stored and thousands of new ones arriving a day, wouldn't the constant trigger calls put a stress on the database? Or am I just getting worried for no reason?


Let's consider non-decreasing sequence of integer not negative numbers and $d_1 \geq d_2 \geq \cdots \geq d_n \geq 0$

Prove that such sequence is a graph sequence  of some graph $G$ which does not contain loops iff $d_1 \leq d_2 + d_3 + \cdots + d_n$. IMPORTANT: by condition $d_1 + d_2 + \cdots + d_n = 2k$ for some integer $k$ I was trying to solve this one by assuming that $d_1 > d_2 + d_3 + \cdots + d_n$. I was planning on coming to contradiction. But I haven't managed to. All ideas for solution will be much appreciated!


How many ways can we let people into a movie theater if they only have half-dollars and dollars?

My interest in combinatorics was recently sparked when I read about the many things that the Catalan numbers count, as found by Richard Stanley. I picked up a copy of Brualdi's Combinatorics, and while browsing the section on counting sequences I found a nice little puzzle that has definitely puzzled me.     Let $m$ and $n$ be nonnegative integers with $n\geq m$. There are $m+n$ people in line to get into a theater for which admission if $50$ cents. Of the $m+n$ people, $n$ have a $50$-cent piece and $m$ have a $\$ 1$ dollar bill. The box offices opens with an empty cash register. Show that the number of ways the people can line up so that change is available when needed is   $$ \frac{n-m+1}{n+1}\binom{m+n}{m}. $$     I first noted that the first person to enter must be one of the $n$ with a half-dollar. Now the register has a half-dollar change. The second person can be either a person with a half-dollar or a dollar. In the first case, the register will now have two half-dollars, in the second case, the register will now have one dollar bill. So it seems to me that when one of the $n$ people with a half-dollar enters, the number of half-dollars in the register increases by $1$, and when one of the $m$ people with a bill enters, the number of half-dollars decreases by $1$ but the number of bills increases by $1$.   I tried to model this by looking at paths in $\mathbb{Z}^2$. The $x$-axis is like the number of half-dollars, and the $y$-axis is the number of bills. You start at $(0,0)$, and you can take steps forward $(1,0)$ or backwards diagonally $(-1,1)$ corresponding to who enters, but you must always stay in the first quadrant of the plane without crossing over the axes. The goal is to make $m+n$ moves, and I figured maybe the number of such paths is counted by $\frac{n-m+1}{n+1}\binom{m+n}{m}$, but I'm not sure how to show this. I don't know if this observation simplifies the problem at all, as I don't know how to finish up. I'd be happy to see how this problem is done, thank you.


Can't connect to minecraft server on Hamachi anymore

Up until a couple of hours ago, I could connect to my Hamachi server from another PC in my local network. But now I can't reach that server any more. In the server list it says "Can't connect to server". When I try to connect anyway, it says "java.net.ConnectException: Connection timed out: no further information" followed by the server's IP address.  The server is operating correctly - I believe - since I can connect with a client on that same computer. The server also hasn't got any mods running.  Hamachi apears to be working correctly too, the PC running the server shows up with a green icon saying "direct tunnel". I also moved my Hamachi connection up in the list to be the default connection. Didn't help. I've also restarting both Hamachi and the Hamachi network adapters, on both PCs.  Java is updated to the latest version on both PCs. There's also a firewall rule allowing both jre6 and jre7 to have inbound and outbound connections.  My logs aren't showing anything out of the ordinary either. Here's an example (that exception starting at line 2 has something to do with the console not showing anything, but that is a completely different matter.). I have tried connecting multiple times here:  [23:30:22] [Server thread/INFO]: Starting minecraft server version 1.7.2 [23:30:22] [Server console handler/ERROR]: Exception handling console input java.io.IOException: De ingang is ongeldig     at java.io.FileInputStream.readBytes(Native Method) ~[?:1.7.0_25]     at java.io.FileInputStream.read(Unknown Source) ~[?:1.7.0_25]     at java.io.BufferedInputStream.read1(Unknown Source) ~[?:1.7.0_25]     at java.io.BufferedInputStream.read(Unknown Source) ~[?:1.7.0_25]     at sun.nio.cs.StreamDecoder.readBytes(Unknown Source) ~[?:1.7.0_25]     at sun.nio.cs.StreamDecoder.implRead(Unknown Source) ~[?:1.7.0_25]     at sun.nio.cs.StreamDecoder.read(Unknown Source) ~[?:1.7.0_25]     at java.io.InputStreamReader.read(Unknown Source) ~[?:1.7.0_25]     at java.io.BufferedReader.fill(Unknown Source) ~[?:1.7.0_25]     at java.io.BufferedReader.readLine(Unknown Source) ~[?:1.7.0_25]     at java.io.BufferedReader.readLine(Unknown Source) ~[?:1.7.0_25]     at ll.run(SourceFile:78) [minecraft_server.1.7.2.exe:?] [23:30:22] [Server thread/INFO]: Loading properties [23:30:22] [Server thread/INFO]: Default game type: SURVIVAL [23:30:22] [Server thread/INFO]: Generating keypair [23:30:22] [Server thread/INFO]: Starting Minecraft server on *:25565 [23:30:22] [Server thread/INFO]: Preparing level "world" [23:30:22] [Server thread/INFO]: Preparing start region for level 0 [23:30:23] [Server thread/INFO]: Done (1,039s)! For help, type "help" or "?"   Here's also my server.properties file:  #Minecraft server properties #Fri Dec 06 23:30:22 CET 2013 generator-settings= op-permission-level=4 allow-nether=true level-name=world enable-query=false allow-flight=false announce-player-achievements=true server-port=25565 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=false spawn-animals=true hardcore=false snooper-enabled=true online-mode=true resource-pack= pvp=false difficulty=1 enable-command-block=true gamemode=0 player-idle-timeout=0 max-players=20 spawn-monsters=true generate-structures=true view-distance=15 spawn-protection=16 motd=A Minecraft Server   Other answers also suggested using port-forwarding. Unfortunately, I can't use that. I'm using Hamachi so that I can host my server from wherever I am with my laptop.  EDIT: I reinstalled Hamachi on both PCs, and started a new Hamachi network, but still nothing.


$AB = C$, prove if $C$ is invertible, then $A$ and $B$

Let $A, B, C$ be $n \times n$ matrices and assume $AB = C$. Prove if $C$ is invertible, then $A$ and $B$ are invertible and specify inverses.


How to find Thevenin equivalent of circuit?

I'm trying to find the Thevenin equivalent for this circuit. I'm confused how to do this, but my solution so far is:   Mesh 1: 0 = 2(I1) + 2(I0) - 2I0(volt source) Mesh 2: = ? Vth = Vab = I1 - I2 Rth = (2+4) * (2+4) / (2+4+2+4) = 3ohm    Is this in the right direction?


What word describes random unfitting accusations

I really dont know how to describe this. Im having a discussion with someone, I was sharing information that I found on a topic. Randomly im called out as being rude when nowhere was there evidence of rudeness exchanged. This person seems to have a history of claiming people have a problem or are being rude out of the random blue.   Is there a word to describe these random accusations that dont connect to anything?


Does anyone know the equation of a 3-Dimensional egg. Like a real egg( the uneven type where it is more wide on one side), not an ellipsoid in 3D cartesian form.I can't seem to find it anywhere, I mean there is one even for the heart in 3D, so there should be one for an egg right?


Can a Time Lord/Lady regenerate into a different race? If a Time Lord/Lady can gender swap, I was wondering this.


Real projective space homeomorphic to sphere

Consider the unit sphere $S^n$ with the equivalence relation that identifies antipodal points of $S^n$. Show that the quotient space $S^n/\sim$ is homeomorphic to the projective space $\mathbb{RP}^n$.  I know that $\mathbb{RP}^n=\overline{B^n}/\sim$, so if I can define a homeomorphism from $\overline{B^n}$ to $S^n$, I think that should be sufficient. My thought was to define a function on the ball so that every point on a line that goes through the origin is mapped to the outermost point, a point on the sphere. But I don't know how to write this explicitly. I have seen questions like this stated, with the explanation I came up with given, but there is no explicit definition of the homeomorphism.


What is the status of apt-get relative to apt?

I use apt for update, full-upgrade, and to install, remove, and purge. Sometimes I use autoremove but it is probably unnecessary because I am not lacking disk space. I do not recall ever needing to use apt-get since I became aware of apt.   Has apt made apt-get unnecessary for the vast majority of users?


The volume “boot” has only 0 byte disk space remaining?

I am in Ubuntu 12.04.  When I install the software updates with "Update Manager", there is a pop up dialog which tells me "The volume "boot" has only 0 byte disk space remaining"  My current kernal in use is:  myname: ~$ uname -r 3.11.0-19-generic   The content of boot folder is:  Laptop1:~$ ls -lah /boot total 215M drwxr-xr-x  4 root root 2,0K abr 26 14:49 . drwxr-xr-x 23 root root 4,0K abr 26 14:48 .. -rw-r--r--  1 root root 983K oct 23  2013 abi-3.11.0-13-generic -rw-r--r--  1 root root 983K nov 12 18:33 abi-3.11.0-14-generic -rw-r--r--  1 root root 983K ene 30 18:53 abi-3.11.0-15-generic -rw-r--r--  1 root root 984K feb  3 23:20 abi-3.11.0-17-generic -rw-r--r--  1 root root 985K mar 11 20:06 abi-3.11.0-19-generic -rw-r--r--  1 root root 985K abr  1 23:08 abi-3.11.0-20-generic -rw-r--r--  1 root root 160K oct 23  2013 config-3.11.0-13-generic -rw-r--r--  1 root root 160K nov 12 18:33 config-3.11.0-14-generic -rw-r--r--  1 root root 160K ene 30 18:53 config-3.11.0-15-generic -rw-r--r--  1 root root 160K feb  3 23:20 config-3.11.0-17-generic -rw-r--r--  1 root root 160K mar 11 20:06 config-3.11.0-19-generic -rw-r--r--  1 root root 160K abr  1 23:08 config-3.11.0-20-generic drwxr-xr-x  5 root root 1,0K abr 26 14:48 grub -rw-r--r--  1 root root  26M nov 23 17:56 initrd.img-3.11.0-13-generic -rw-r--r--  1 root root  26M dic 24 14:55 initrd.img-3.11.0-14-generic -rw-r--r--  1 root root  26M feb  1 20:46 initrd.img-3.11.0-15-generic -rw-r--r--  1 root root  26M feb 22 14:00 initrd.img-3.11.0-17-generic -rw-r--r--  1 root root  26M abr 22 20:57 initrd.img-3.11.0-19-generic -rw-r--r--  1 root root  26M abr 26 14:48 initrd.img-3.11.0-20-generic drwx------  2 root root  12K oct 30 21:03 lost+found -rw-r--r--  1 root root 173K jun 17  2013 memtest86+.bin -rw-r--r--  1 root root 175K jun 17  2013 memtest86+_multiboot.bin -rw-------  1 root root 3,2M oct 23  2013 System.map-3.11.0-13-generic -rw-------  1 root root 3,2M nov 12 18:33 System.map-3.11.0-14-generic -rw-------  1 root root 3,2M ene 30 18:53 System.map-3.11.0-15-generic -rw-------  1 root root 3,2M feb  3 23:20 System.map-3.11.0-17-generic -rw-------  1 root root 3,2M mar 11 20:06 System.map-3.11.0-19-generic -rw-------  1 root root 3,2M abr  1 23:08 System.map-3.11.0-20-generic -rw-------  1 root root 5,4M oct 23  2013 vmlinuz-3.11.0-13-generic -rw-------  1 root root 5,4M nov 12 18:33 vmlinuz-3.11.0-14-generic -rw-------  1 root root 5,4M ene 30 18:53 vmlinuz-3.11.0-15-generic -rw-------  1 root root 5,4M feb  3 23:20 vmlinuz-3.11.0-17-generic -rw-------  1 root root 5,4M mar 11 20:06 vmlinuz-3.11.0-19-generic -rw-------  1 root root 5,4M abr  1 23:08 vmlinuz-3.11.0-20-generic   Questions:  Among those files in boot folder, which can be removed?  Thank you:)


Did Time Lords grant The Doctor enough regeneration energy to have more than one regeneration?

In Time of The Doctor, Time Lords gave The Doctor regeneration energy using which The Doctor regenerated. Does the 14th Doctor (commonly known as 12th) have any regeneration energy left? Can he regenerate again (using the same regeneration energy)?


You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 's stan',

I have this error. I don't know where is mistake. Can anyone help me? Here is my code:  <?php         include 'config.php';                            if ($tip_vesti == 'Vest') {         $sql = "INSERT INTO `vesti`(`tip`, `naslov`, `uvod`, `vest_image`, `razrada`, `zakljucak`, `video`, `date`)                      VALUES ('$tip', '$naslov', '$uvod', '$vest_image', '$razrada', '$zakljucak', '$video', '$date')";         } else if ($tip_vesti == 'Odaberi jedno') {             $error = "Molimo odaberite tip vesti";         } else if ($tip_vesti == 'Transfer') {             $sql = "INSERT INTO `transferi`(`tip`, `naslov`, `uvod`, `vest_image`, `razrada`, `zakljucak`, `video`, `date`)                      VALUES ('$tip', '$naslov', '$uvod', '$vest_image', '$razrada', '$zakljucak', '$video', '$date')";         } else {             $sql = "INSERT INTO `blogovi`(`id_user`, `tip`, `naslov`, `uvod`, `vest_image`, `razrada`, `zakljucak`, `video`, `date`)                      VALUES ('$id_user', '$tip', '$naslov', '$uvod', '$vest_image', '$razrada', '$zakljucak', '$video', '$date')";         } ?>


Number of arrangements of the letters of the word "MISSISSIPPI" if all the S's and P's are separated.

If the number of arrangements of the letters of the word "MISSISSIPPI" if all the S's and P's are separated is $K\cdot\dfrac{10!}{4!\cdot4!}$ then $K$ equals  My attempt is as follows:-  Assuming question is asking to separate all instances of S and all instances of P but S and P can be together  First arrange $M,I,I,I,I$, they can be arranged in $\dfrac{5!}{4!}=5$ ways  $5$ characters will give $6$ gaps, so choose any $4$ gaps out of $6$ and insert $S's$ over there $\implies \displaystyle{6\choose 4}$  Now we have $5\cdot\displaystyle{6\choose 4}$ arrangements containing $9$ characters and all $S's$ are separated. Now its time to push $P's$  $9$ characters will give $10$ gaps, so choose any $2$ gaps out of $10$ and insert $P's$ over there $\implies \displaystyle{10\choose 2}$  So total arrangements will be $5\displaystyle{6\choose 4}{10\choose 2}=5\cdot\dfrac{6!}{4!\cdot 2!}\cdot\dfrac{10!}{2!\cdot 8!}=\left(\dfrac{5\cdot 4!}{2!\cdot 2!\cdot 8\cdot7}\right)\dfrac{10!}{4!\cdot 4!}$  $$K=\dfrac{15}{28}$$, but actual answer is $K=1$  What mistake am I doing here?


I bought a Mac Mini mid 2011 and sometimes i have an hard reboot. I thought it was a power problem and I replaced it but nothing seems to have changed.  If i execute log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 1h the result is kernel: (AppleSMC) Previous shutdown cause: -128  I searched online but i cannot find anything.  Any suggestion?


To prove that if $n$ is odd, then $8 \mid n^2−1$, observe that as $n$ is odd either $n = 4k+1$ for some integer $k$ or $n=4k+3$ for some integer $k$. In the first case $n^2 -1=8(2k^2+k)$ and in the second case $n^2-1 = 8(2k^2 + 3k + 1)$.  Given an odd integer $a$, establish that $a^2 +(a+2)^2 +(a+4)^2 + 1$ is divisible by $12$. Solve by consideration of six cases.


How did the equation $|A- \lambda I| = 0$ came for finding Eigen values of a Matrix

Does anyone know how this equation came.I was studying about Eigenvalues and a doubt that arised was how could the equation $(A- \lambda)V = 0$ become $|A- \lambda I| = 0$.


How rotating body have same angular velocity and acceleration

Does a body rotating about a fixed axis have to be perfectly rigid for all points on the body to have the same angular velocity and the same angular acceleration


What is physical interpretation of dot product?

Consider two vectors $V_1$ and $V_2$ in $\mathbb{R}^3$. When we take their dot product we get a real number. How is that number related to the vectors? Is there any way we can visualize it?


It seems to me that the set of all numbers really used by mathematics and physics is countable, because they are defined by means of a finite set of symbols and, eventually, by computable functions.  Since almost all real numbers are not computable, it seems that real numbers are a set too big and most of them are unnecessary.  So why do mathematicians love this plethoric set of numbers so much?


does Voice of the Chain Master effectively replace Devil's Sight If the warlock's familiar is an imp?

to me, the Voice of the Chain Master invocation reads that it completely upgrades the basic Find Familiar spell, increasing the range of the telepathic communication to 100 feet and no longer requiring an action to perceive through its senses.  I have read Crawford's Sage Advice saying you still require an action, but that was 4 years ago and he is known to change his rulings (though it might not have changed, just that people have not asked in a while)


locally on $S$ one of the coordinates is a $C^∞$ function of the other coordinate. Show that $S$ is a submanifold of $R^2$

Suppose that a subset $S$ of $R^2$ has the property that locally on $S$ one of the coordinates is a $C^∞$ function of the other coordinate. Show that $S$ is a regular submanifold of $R^2$  My prof gave me a hint saying we must take charts $(U,x,y-f(x))$ and $(V,x,y-g(x))$ and show they are compatible and so are their adapted charts. What does he mean?  A subset $S$ of a manifold N of dimension $n$ is a regular sub- manifold of dimension k if for every p ∈ S there is a coordinate neighborhood $(U, φ ) = (U, x_1 , . . . , x_n )$ of p in the maximal atlas of N such that U ∩ S is defined by the vanishing of n − k of the coordinate functions. By renumbering the coordinates, we may assume that these n − k coordinate functions are $x_{k+1} , . . . , x_n$ .


Assignment behavior differs for whole object and its attributes

For example we have the following JavaScript code:  function f(o) {     o.message = "set in f";     o = {         message: "new object!"     };     console.log(`inside f: o.message="${o.message}" (after assignment)`); } let o = {     message: 'initial value' }; console.log(`before calling f: o.message="${o.message}"`); f(o); console.log(`after calling f: o.message="${o.message}"`);   In these particular lines  o = {     message: "new object!" };   we are creating new object with name 'o', but in the previous line  o.message = "set in f";   we are modifying attribute of the original object with name 'o' (hence modifying the object itself in my understanding).  My question is why does assignment behavior differ in these situations? Shouldn't it be the same for object itself and its attributes?  For example 'o' assignment in the function body should have changed the original 'o' object instead of creating new one.


finding size of a structure in c language

In a structure of node size of data is 4 bytes and the size of node* is 8 bytes while the size of node is 16 bytes. After 4+8=12 where is 4 extra bytes of node?    I do not understand anything about this.  struct node {     int data;     struct node* next; }s; int main() {      printf("node => %d \n",sizeof(s));      printf("node.data => %d \n",sizeof(s.data));      printf("node* => %d ",sizeof(s.next));  return 0;  }  /*OUTPUT-   node => 16   node.data => 4  node* => 8 */


Is there a way to find out how much it would have cost to buy a particular airplane ticket at some point in the past?    For example, how could I find out how much it would have cost to buy a one-way itinerary from airport A to airport B on October 1, 2011 for travel on November 1, 2011?


How to decode blob code from base64 using java?

i have to test if the cvs file exists and could be downloaded from a webapp, So in the download link element, i see this :  <a class="" target="_blank" download="Myfile(2014-07-01 2014-07-31).csv" href="blob:de3889b8-23d4-4776-bn8f-68f34911fad9">   it is encoded in Base64 using java.  How can i decode the content of href in order to download the csv file? Thank you


Why is Hamilton's Principle not the 'Principle of Least Action'?

Hamilton's Principle is that the first order variations of $\displaystyle\int^{t_2}_{t_1} L$ $ dt$ for an on-shell trajectory in the configuration space should vanish provided the varied off-shell trajectories meet the on-shell trajectory at $t_1$ and $t_2$.   The only reason I can think of as to why this should not be called the Principle of Least Action is that it is not - it is the Principle of Stationary Action. But leave that distinction aside for a moment because it is sort of irrelevant for the doubt that I have, as will become clear in the rest of my post.   The issue that I have is that my Professor is insisting that the condition obtained on the ''$\Delta$ - variation" of $\displaystyle\int^{t_2}_{t_1} L$ $ dt$ about an on-shell trajectory in the configuration space for a system with conserved Hamiltonian (both on-shell and off-shell) is exclusively what should be called the Principle of Least Action. This condition is that $$\Delta \displaystyle\int^{t_1}_{t_2}p\dot q dt=0$$ where the $\Delta$-variation is defined as the following:  $$\Delta \displaystyle\int^{t_1}_{t_2}p\dot q dt=\displaystyle\int^{t_1+\Delta t_1}_{t_2 + \Delta t_2}p\dot q dt + \delta \displaystyle\int^{t_1}_{t_2}p\dot q dt$$ with a key difference from the variations considered in the Hamilton's principle that apart from varying the limits of integration as well, we do not require the varied off-shell trajectories to coincide with the on-shell trajectory at the end-points of the on-shell trajectory.   Now, I have always read that $\displaystyle\int L dt$ is what is called action and thus, I think that a variational principle associated with the same should be called the Principle of Least (Stationary) Action. Whereas $\displaystyle\int p\dot q dt$ defer from $\displaystyle\int L dt$ by $\displaystyle\int H dt$ - jeopardizing the possibility of its variational principle's to be called "Principle of Least (Stationary) Action" (leave alone an exclusive right to be called so).


Java method with changing parameters inside a loop

I'm calling this method inside a while loop in main method. Unless i set the string in as kayit when i declare it, following if blocks doesn't get executed.  void handleInput(Ziyaretci ziyaretci, ArrayList<Musteri> musteriler,  int sayac) {     Scanner girdi = new Scanner(System.in);     boolean sw2 = true;     String in;     in = girdi.next();     if (in == "kayit") {         String isim = "nll";         String sifre = "sifre";         System.out.println("Kullanici ismini gir: ");         while (sw2) {             isim = girdi.next();             sw2 = false;             for (int i = 0; i < musteriler.size(); i++) {                 if (musteriler.get(i).isim == isim) {                     System.out.println("Bu kullanici ismi kullaniliyor :( Başka bir isim dene");                     i = musteriler.size();                     sw2 = true;                 }             }                }         System.out.println("Sifreni gir: ");         sifre = girdi.next();         if (ziyaretci.ekle(isim, sifre, sayac, musteriler))              System.out.println("Kayit islemi basarili bir sekilde gerceklestirildi.");         else              System.out.println("Kayit islemi sirasinda beklenmedik bir hata meydana geldi");     } }


Omitting "INTO" in "INSERT INTO" Statement

You can apparently interchangeably include or omit INTO in INSERT statements at least both in MySQL and SQL Server:  -- works: INSERT INTO Table (Column) VALUES (1); -- also works: INSERT Table (Column) VALUES (1);   Why is this and which approach should be taken?


A common saying like in Hindi "Juldi ka kaam shaitan ka" translation "Anything done in hurry has Satan's reflection in it. "  Something like truism, but it's meaning on google doesn't say what I mean. I want a word for "truism but useful."


Show that any metrizable space $X$ is Hausdorff

I wish to show that any metrizable space $(X,\mathcal{T})$ is Hausdorff  Proof attempt:  Let $d$ be the metric that generates the topology on $X$. Pick two points $x,y \in X$, we wish to produce two disjoint open sets that separates $x,y$.  Let $B_\epsilon(x)$ and $B_\delta(y)$ be two metric balls containing $x,y$ respectively. Suppose that  $B_\epsilon(x) \cap B_\delta(y) \neq \varnothing$       Stuck Here: Hmm...How should I adjust $\epsilon, \delta$ so that these   balls are separated?   Idea: Reduce $\epsilon$ by half. If they are still intersecting...reduce $\delta$ by half. Continue ad infinitum         Is there a more satisfying solution i.e. closed form expression for   reduced $\epsilon, \delta$ so they are no longer intersecting. Thanks!