Make the search box return results from all StackOverflowian sites?

There should be an easy way to search Server Fault from Stack Overflow (and the others)  The easiest thing would be to add a "Try searching Server Fault" link next to the "Alternately, try your search in Google:" on the no-results page, but this wouldn't help with overlapping searches..  For example, searching for [sql] error 1234 might have better results of ServerFault, but a programmer might only searching SO for such a problem (a reasonable thing to do)  Maybe there could be a SO/SF/SU/Meta buttons at the top of the search results, which jump you between sites?  Since the user may not be logged into ServerFault, I guess it'd be best to display the results on the current site (with the different colour scheme maybe?), obviously all the links would go to the correct site (http://serverfault.com/questions/... in the example image)  A good example of such a feature is Google.


Binding an enum to MVVM Light RelayCommand CommandParameter

I'm trying to bind the command parameter in XAML for a RelayCommand<MessageTokens> as below, where MessageTokens is an enum   public ICommand OpenInvoiceWindowCommand         {             get             {                 return _openInvoiceWindowCommand ??                        (_openInvoiceWindowCommand = new RelayCommand<MessageTokens>(OpenInvoiceWindow, prm => CanExecuteOpenInvoiceWindowCommand));             }         }   The XAML is:    <Controls1:RadMenuItem Command="{Binding SupplierInvoiceViewModel.OpenInvoiceWindowCommand}" CommandParameter="{Binding Source={x:Type ShipmentDetails:DebitInvoiceViewModelBase}, Path=MessageTokens.SupplierInvoice}" Header="Register a supplier's invoice"/>   Using Telerik's RadGridView the code crashes with      at GalaSoft.MvvmLight.Command.RelayCommand`1.CanExecute(Object parameter)    at Telerik.Windows.Controls.RadMenuItem.CanExecuteApply() in c:\Builds\WPF_Scrum\HotFix_2010_Q3\Sources\Development\Controls\Navigation\Menu\RadMenuItem.cs:line 2105    at Telerik.Windows.Controls.RadMenuItem.ChangeCommand(ICommand oldCommand, ICommand newCommand) in c:\Builds\WPF_Scrum\HotFix_2010_Q3\Sources\Development\Controls\Navigation\Menu\RadMenuItem.cs:line 2124    at Telerik.Windows.Controls.RadMenuItem.OnCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) in c:\Builds\WPF_Scrum\HotFix_2010_Q3\Sources\Development\Controls\Navigation\Menu\RadMenuItem.cs:line 1623    at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)    at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)    at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)    at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)   etc.  If I change the parameter to RelayCommand<string> instead of RelayCommand<MessageTokens> the code runs fine.  I'm loathe to do this since I lose all the benefits of strongly typing my parameters.  I suspect that I am not declaring the enum properly in XAML. I've tried     CommandParameter = "<fullpath>..MessageTokens.SupplierInvoice>"   but that gives an InvalidCastException in MVVMLight.  Does anyone have any suggestions?  Many thanks Jeremy     Edited with the solution   The issue was because I wasn't properly referring to the inner class in the CommandParameter binding with the + sign.  the correct XAML should be:  <Controls1:RadMenuItem Command="{Binding SalesInvoiceViewModel.OpenInvoiceWindowCommand}" CommandParameter="{x:Static local:DebitInvoiceViewModelBase+MessageTokens.SalesInvoice}" Header="Raise a sales invoice"/>


Is a complex matrix A such that A^k = I; the n×n identity matrix and where k>1 diagonalizable provided that 1 is not an eigenvalue of A.


How can I sync two timers (client / server) when epoch times differ slightly between devices?

This is a question that I'm curious about, for perfectionism sake. It's not a problem that I'm completely stuck on.  I have a webpage that enables me to set a countdown timer. This countdown timer runs on the server, so an action can be executed when the timer finishes, even if the webpage has been closed.   I suspected it would be as simple as sending the endtime for the timer to the server, getting the current time on the server, set a timeout (NodeJS), and that's it. However, when I do this, the timer on the server finishes about 1.5 seconds before the one on the webpage, consistently. Like I said, this is not a big problem at all, but it made me wonder.  Something else I thought of, while thinking about this problem, was calculating the difference in time between now and the endtime on the webpage, sending this delta to the server, and setting a timeout with this delta. For my case (LAN only), I think this would pretty much "fix" the issue, since I don't expect any network hickups on my LAN. However, when something does go wrong, the timers obviously would be completely out of wack.  So how can I get these two timers "perfectly" synced?


Title of a book about trying to control “the moment”

I read this book which I think is from the early 2000s. I don’t know what it is called, who wrote it, or who published it, so I’m hoping a kind soul can help me out.  There’s this extra-dimensional construct call “the moment” in which a single instant of time or all of time itself can be inhabited. Characters in the book discover how to access “the moment,” and then different groups fight to control it. Their incursions into “the moment” begin to harm the future, kind of like a butterfly effect.  Has anyone read this thing before?


$\int_{I^n}(\min_{1\leq i\leq n} x_i)^a dx$

Let $I=[0,1]$. Find  $$\int_{I^n} \left(\min_{1\leq i\leq n} x_i \right)^a dx,$$  for $a\in \mathbb{R}$. Please help to solve this. Thank you.


For matrices $A, B, C,\,$ If $AC=BC$, can we say that $A=B$?

Suppose we have $n\times n$ matrices $A, B$, and there is no information about singularity of $A, B$.   Also $C$ is a $n\times n$ projection matrix, i.e. singular matrix and it is not the zero metrix.  If $AC=BC$, can we say that $A=B$?  All comments would be appreciated.


Comments aren't displayed on Area 51 if the comment section has to be expanded

I commented on a question on Area 51 two hours ago. The question having received over 5 comments, one has to expand the comment section to view all comments. However, mine does not show up:    Someone replied to my comment and it also doesn't show up, either to them or to me.  Link to the question:


Can I mill an opponent who has Emrakul, the Aeons Torn by comboing until opponent's deck is stacked in an exact way?

Let's say I'm running a mill deck. I have some kind of infinite mill combo ready and available (e.g.  imprinting a creature,  and  - this lets me sacrifice Myr Retriever to Grinding Station, retrieve another Myr Retriever, mill opponent for 3 cards, and cast a new Myr Retriever for free). However my opponent has two copies of  in his deck. Since Emrakul shuffles back in to the deck each time it's put into the graveyard, this means I can't actually mill him out.  However, through repeated use of the mill combo I can in principle 1) figure out every card in his deck, and then 2) mill him until the last three cards in his deck are Emrakul, Emrakul, and [irrelevant card] (I assume here the number of cards in opponent's deck before I start the mill combo is divisible by three). This means opponent must hard cast Emrakul to win, and I already know (e.g. via ) that he doesn't have the resources to do this. So I win anyway by milling in three turns.  This kill will take a long time to execute, for obvious reasons, because each time I mill an Emrakul it gets shuffled back into opponent's deck. I'll need the deck to be stacked in exactly such a way that the two Emrakuls + an irrelevant card are at the bottom of the deck. This will happen eventually, just probably not for a very long time.  Question: can I actually execute this kill in paper, or will standoff rules kick in first?


I see pictures online of everyone having all these Pokémon to catch being everywhere around them, but it seems like I can only ever see one or two. I live in a rural area, but even walking miles through the farmland, it's rare to find any Pokémon.  Why is this? How can I find more Pokémon?


How to make a ISO image from a Bootable DVD in windows?

I am using Windows 7. And I want to install ubuntu 12.04 to my new Notebook PC. It has no DVD-ROM so I wanna make *.iso file so I can install it fom a usb. I have the Ubuntu 12.04 bootable DVD. How to make those files in the DVD a iso image?


I am wondering why the 2nd if statement is not being evaluated to true...   while ((tmp = yearReader.readLine()) != null) {         if(tmp.length() >= 22){             System.out.println(tmp.substring(0, 12));             if(tmp.substring(0, 12) == "
<a href="){                 System.out.println("This should print...");             }         }     }   Prints this...
<a href=
<a href=
<a href=


When a block in resting on a table (the table is on Earth) the table stops the block from going more down, from where does it get the energy to apply a force opposite to gravity?


Difference between using #include and #include in C++

What is the difference between using #include<filename> and #include<filename.h> in ? Which of the two is used and why is it is used?


How can I capture the result of var_dump to a string?

I'd like to capture the output of  to a string.  The PHP documentation says;     As with anything that outputs its result directly to the browser, the  can be used to capture the output of this function, and save it in a string (for example).   What would be an example of how that might work?  print_r() isn't a valid possibility, because it's not going to give me the information that I need.


Is there a word that describes this gesture of interlocking hands on the lower stomach?

Specifically, I am referring to the traditional gesture some female service staff members seem to do, when demonstrating their work or their readiness to receive orders.  Also, this is the gesture Alice Cullen performs in Twilight movies on several occasions (if I remember correctly).  I could not find a photo with this exact gesture. It is similar to the one shown in the first photo, but the hands are held higher with demonstrativeness, tension, sharpness of movement and gesture itself (possibly with emotion and a smile), and military-like demeanor. The main difference with with the second photo is that in the gesture I refer to, the hands are held in the front and not in the back; also, the way the hands are interlocked is different (more like in the first picture).


"My wife and I am": Singular / Plural and the rule of proximity issue

"My wife and I am" = one family, a singular number. Therefore satisfies  the use of "am" for both number and proximity issues.


$\delta : C([0,1])\to\mathbb{R}$, $f\mapsto f(0)$, with sup-norm is bounded but unbounded with one-norm.

The following is a problem out of Hunter's Applied Analysis that I am working on. I am looking for proof verification for the first part, and any constructive feedback/hints/tips for the second part of the question.     Let $\delta : C([0,1])\to\mathbb{R}$ be the linear functional that evaluates a function at the origin $\delta(f)=f(0)$. If $C([0,1])$ is equipped with the sup-norm,   $$\|\ f \|_{\infty} = \sup_{0\leq x\leq 1} |f(x)|,$$   show that $\delta$ is bounded and compute its norm. If $C([0,1])$ is equipped with the one-norm,   $$\|\ f \|_1 = \int_0^1 |f(x)|dx,$$   show that $\delta$ is unbounded.    First recall that for normed spaces $(X, \|\ \cdot \|_X)$ and $(Y, \|\ \cdot \|_Y)$ the norm of a linear operator, $T:X\to Y$ is defined as: $$\|\ T \|_{\text{op}} = \sup_{\|\ x \|_X = 1} \|\ Tx \|_Y $$ So in our example we're tasked with finding  $$\|\ \delta \|\ = \sup_{\|\ f \|\ = 1} \|\ \delta(f) \|\ = \sup_{\|\ f \|\ = 1} |f(0)|$$ Then, note that  $$\|\ \delta \|\ =\sup_{\|\ f \|\ = 1} |f(0)| \leq \sup_{\|\ f \|\ = 1 } \left( \sup_{0\leq x\leq 1}|f(x)| \right) = \sup_{\|\ f \|\ = 1 } \|f\|_{\infty} = 1 $$ this establishes that $\delta$ is bounded.   As far as the second bit of the question, consider the norm as: $$\|\ \delta \|\ = \sup_{\|\ f \|_1 \neq 0} \dfrac{\|\ \delta(f) \|\ }{\|\ f \|_1 } = \sup_{\|\ f \|_1 \neq 0} \dfrac{|f(0)|}{\|\ f \|_1 } $$ So I want to show the existence of an $f\in C([0,1])$ such that $f(0)= c > 0$ and $\int_0^1 |f(x)| = 0$. My first thought was $\cos(2\pi x)$ but the absolute value messes that example up. Anyway, needless to say, I'm stuck here. Any tips or hints?


finding a value in a JSON object (Python)

I have a JSON object in Python that represents operation data, and it's heavily nested. In constructing my UI for it, it looks like I'll need to show a section of it in a tree view.    Is there a way to find a key in a JSON object in Python? From the docs, it doesn't look like it. I could write something to traverse the object and find it, but if there's an out of the box way, that'd be preferable. Is there such a way?    Thank you for your time.


Design of the frontpage is broken at 110% zoom

The frontpage looks like the following screenshot for me as I have a zoom level of 110% set:    It looks perfectly fine if I set the zoom to 100%, but then the text is a bit too small for me. I'm using the latest Chrome on Windows 7.


How many ways can you pick from a list when for each pick you can either pick 1 or 2 items from the list?

Suppose you have x amount of bagels, each day you must eat 1 bagel minimum or 2 bagels maximum..how many different ways can you eat all the bagels?


A number with 6 distinct digits which get multiplied by 5 if we move the last digit to front

There is a number with 6 different digits, if we pick the last digit of that number and place before that number we got $5$ times our number.  How to find such a number?


Any Dice Help - Reroll 1's in dice pools

I have made some progress in AnyDice showing the probability for dice resolution system in the RPG system I've been working on. Here is the link to what I have so far:   I need particular help on when a roll gets a 2 or 3 that that die can be rerolled once. I am interested to see how this alters the probability of success.


Today I asked a question on this site regarding inertia, and while reading one of the answers, a question popped up  Why does a body have inertia?  I looked up this site and several others, but could not find any resources.


For what integer values of $y$ is $\frac{3y-1}{y-3}$ an integer?

I have encountered this as part of a bigger problem but I really don't know how to go on about it. I would also appreciate it if you could specify a certain technique to follow when facing such a problem.


Quick doubt about chinese theorem: Giving the wrong answer

i was doing an exercise, where I ended up with this equation: $p = 1 mod (5)$ $p = 1 mod (2)$ I was trying to use Chinese theorem to see what number p takes form, but it is giving a wrong answer: $p = \sum a^{i}x^{i}M^{i}$ $a^{i} = x^{i} = 1$ $p = \sum M^{i}$ $ p = 5 + 2 = 7$ :q


How do I search for a hidden file in macOS?  I know the Command Shift . shows hidden file on Finder, but I am looking for a way to search for it.  For Example, I want to look for .npmrc file, and it does not find it in SpotLight nor in Finder Search


Why doesn't terminal show color schema once logged as root?

I'm currently using Debian 7 Wheezy, and I've noticed that the colors palette on terminal (which might be useful to identify among a large set of files and folders) are not enabled once I log as root.  Same, I've noticed the tab completion doesn't work the same in this situation.  How can I configure these issues?


Is the salt value a secret or can it be stored in cleartext just like the IV?

From Wikipedia I read that the IV is used to randomise the mapping of cleartext to cipher text and that the IV is usually stored (in cleartext) together with the encrypted record. ()  However if I look at a specific implementation in C# when deriving the key using Rfc2898DeriveBytes, a salt value is required and I understand the need of the salt. But obviously I will need the salt later on the regenerate the key from my secret passphrase. Does that imply that the salt itself is not a secret and can be stored together with the encrypted record in cleartext, just like the IV?  string passphrase = "Hello World, I'm the secret!"; string salt = "13245678";  var deriveBytes = new Rfc2898DeriveBytes(passphrase, Encoding.UTF8.GetBytes(salt), 50000);  using (var rijndael = new RijndaelManaged()) {     rijndael.KeySize = 256;     rijndael.Key = deriveBytes.GetBytes ( rijndael.KeySize / 8 );     rijndael.IV = deriveBytes.GetBytes ( rijndael.BlockSize / 8 );   ... }


Setting Objects to Null/Nothing after use in .NET

Should you set all the objects to null (Nothing in VB.NET) once you have finished with them?   I understand that in .NET it is essential to dispose of any instances of objects that implement the IDisposable interface to release some resources although the object can still be something after it is disposed (hence the isDisposed property in forms), so I assume it can still reside in memory or at least in part?  I also know that when an object goes out of scope it is then marked for collection ready for the next pass of the garbage collector (although this may take time).  So with this in mind will setting it to null speed up the system releasing the memory as it does not have to work out that it is no longer in scope and are they any bad side effects?  MSDN articles never do this in examples and currently I do this as I cannot  see the harm. However I have come across a mixture of opinions so any comments are useful.


If $0\leq A\leq B$ on Hilbert space and $A^{-1}$ exists, show that $A^{-1}\geq B^{-1}$

Does  anyone know how to show this? Let $H$ be a Hilbert space and $A$, $B$ bounded positive operators defined on $H$ such that $A^{-1}: H \rightarrow H$ exists and hence bounded and $A \leq B$. Therefore, $B^{-1}: H \rightarrow H$ exists and bounded. Show that $A^{-1} \geq B^{-1}$.   I tried to use this theorem "If two bounded self-adjoint linear operators $S$ and $T$ on a Hilbert space $H$ are positive and commute, then their product $ST$ is positive." However, I don't know whether $A$ and $B$ commute with each other. Are there any other ways to deal with it? I am using book of Kreyszig.


Can I only target other creatures, not myself, when casting spells such as Invisibility that target "a creature you touch"?

Invisibility reads: "A creature you touch becomes invisible until the spell ends..."  Greater Invisibility says: "You or a creature you touch becomes invisible until the spell ends..."  By omission, does this suggest that one cannot use Invisibility on oneself?


Ubuntu not booting after upgrade to 20.04 from 18.04

I upgraded Ubuntu to 20.04 from 18.04. But after the upgrade I'm having trouble booting my system. I'm getting the following message displayed: **/lib/systemd/systemd-udevd: error while loading shared libraries: liblzma.so.5: cannot open shared object file: No such file or directory Gave up waiting for root file system device. Common problems: - Boot args (cat /proc/cmdline) - Check rootdelay= (did the system wait long enough?) - Missing modules (cat /proc/modules; ls /dev) ALERT! UUID=................................ does not exist. Dropping to a shell! BusyBox v1.30.1 (Ubuntu 1:1.30.1-4ubuntu6.3) built-in shell (ash) Enter 'help' for a list of built-in commands. (initramfs)**  I tried a few solutions from various forums that involved booting with a live USB stick, but nothing worked. Please somebody suggest how to rescue this. I'm really falling behind with my work. Ubuntu is installed on sdb4.


Show that $n^5-n$ is divisible by 80 given that n is an odd integer greater than 1.

I tried to prove it by simple binomial expansion but I am stuck.  I assumed, $n=(2k+1) ,k=1,2,3,......$ and after expanding the expression $(2k+1)^5-(2k+1)$ I arrived at this expression$→$ $8k+40k^2+80k^3+80k^4+32k^5$. Now I cannot proceed further with the first, second and last term hindering my approach..  Can anyone please help me with this? Also, it will be great if you can give me some other ideas (like with Fermat's theorem) for this sum.  Thank you..


It's been a while since I've been invited to a private beta and here are some thoughts on my experience with accessing the Sustainability private beta.  On my laptop I wasn't logged into the SE network. When I clicked on the invitation link and  went through to the landing page I was only provided an option to sign up for an SE account. I then clicked on the login option on the top banner I was then allowed to choose to sign in with my Google OpenID.  Just now I tried to access the site with my mobile phone. I was already logged into the SE network on a few sites. When I went to the new Sustainability site I was not given any option to log in, although I am already signed in to the SE network and I already have an invitation. I do understand that I wasn't following the invite link, but to me it shouldn't be that hard to sign me in, check if I'm invited and then pass me through. I'm sure there is a reason it was done this way, but again, it feels kind of clunky for a user with an invite to not be able to log into the site without having to open my email.  I then opened the Area 51 Sustainability page (already signed in to A51 account) to see if I could log in from there to save me the hassle of having to experience Hotmail on my phone, but clicking the "Visit the site now!" link from Area 51 only took me to the same page.  After opening my Hotmail account I clicked on the link and went through to the site. However unlinke on my laptop the mobile version took me immediately to a page where I was given options to choose my Open ID provied e.g. Google. Not sure if this is because I was already signed into the SE network or not.  No major dramas, just a bit awkward on the usability side.


What will the universe look like for anyone falling into a black hole?

I've heard that, from the perspective of an external observer, something falling into a black hole will eventually look "frozen": light waves will move to the infrared and further into lower frequencies.  But what about that unfortunate individual falling into such a black hole? What will he/she see when looking back at our universe?   For instance, I wonder, will it be the ultimate end of the Universe? Can someone who just crossed events horizon of the black hole still receive messages from our side?


I have this confusion related to PCA. Lets say I have a 100 dimensional data, then the projection into the first principal component is given by the average over all the dimensions.  How is it so?


I am trying to design the following table. The cells in the third and fouth row are merged. I tried multicolumn makes more column but I could not manage to do it in way that it merges.


Is the answer “Don't do that” an acceptable response to a “how do I” question?

Hold up! before you click that button to report this question as a duplicate of , consider that not only is that question 10 years old, but is also fairly non-specific, and doesn't make good use of the  blog post in the following year.  To fix a 10 year old question and expect new answers is to paint a 10 year old car and expect to sell it for MSRP.   This question is about questions that begin with "how do" or "how does", meaning questions about methodology and application. It's been a meme in most outside communities that on stack exchange the answer to the question "How do I do A" is objectively "No, don't do A, do B instead". While this may be helpful in some instances, it's at the least, very condescending.  This means this question is actually two wrapped up in eachother, and very intertwined. The first is, as above, "Is the answer "Don't do that" an acceptable response to a "how do I" question?". The second is then, following the first, "When can we assume that the person doesn't actually want to know what their question asks?" The very two are asking two parts of the same scale.  I want to throw one more subject into the ring just to make answers more concise, and cut-throat. Stack exchange isn't know for being particularly "nice". Despite the "Be nice" policy employed site wide, many users feel that they are rejected for asking questions that may be trivial to others, even if a bit ignorant. The epitome of this, in my opinion, is EE.SE, who usually refuse most (even slightly) ignorant, questions based on . This has caused a huge riff in the community over the years. Going back to good subjective bad subjective,  the riff appears in the professional elites, which, in a sense are the 'top 1%ers' of the site, controlling a majority of the reputation and the subjective commoners. There have been multiple people who straight up leave because the users there won't abide to said arbitrary standards, and as such the "don't so that" is said a lot there. Thus the question I want to throw in is: Does your answer support the "Be nice" policy, and will your answer have a positive effect on users if what your answer was the rule?  So let me repeat my questions: Is the answer "Don't do that" an acceptable response to a "how do I" question? When can we assume that the person doesn't actually want to know what their question asks? Does your answer support the "Be nice" policy, and will your answer have a positive effect on users if what your answer was the rule?  I encourage all to use examples of "Don't do it" answers in your answer.


Is the "Amazon Basics" tripod worthwhile for night landscapes and astrophotography?

I am learning photography. I am really interested in night landscapes, moon, star trails. I need a cheap tripod, but not a useless one. Is the  worth getting? It's 60 inches. I'm 73.5 inches tall.


Stop Excel from automatically converting certain text values to dates

Does anyone happen to know if there is a token I can add to my csv for a certain field so Excel doesn't try to convert it to a date?  I'm trying to write a .csv file from my application and one of the values happens to look enough like a date that Excel is automatically converting it from text to a date.  I've tried putting all of my text fields (including the one that looks like a date) within double quotes, but that has no effect.


Find the mean and variance of a random variable that is the absolute value of a normal distribution

Let $X \sim \text{Normal}(\mu, \sigma^2)$. Let $Y = |X|$. Find the pdf of $Y$, as well as $\mathsf E(Y)$ and $\mathsf{Var}(Y)$.  I'm assuming if I can just find the pdf, it'll be simple to find the expected value and variance. I've done method of transformations before, but the absolute value is just throwing me off.   EDIT: I found the pdf to be $\frac 1{\sigma\sqrt{2\pi}}e^\frac {-(y-\mu)^2}{\sigma^2} - \frac 1{\sigma\sqrt{2\pi}}e^\frac {-(y+\mu)^2}{\sigma^2}$, which is the folded normal. However, I still cannot figure out how to get $E(Y)$ and $Var(Y)$.


If my friend has GTA 5 for 360 and I have one can I invite them to my game online?

My friend and I want to play GTA 5 together online, but I have an Xbox one and she has an Xbox 360. Can I join or invite them to my game so we can play together?


Proving $S_n$ is generated by the set $\{(1\text{ }2),(2\text{ }3),\cdots,(n-1\text{ }n)\}$ of $n-1$ transpositions.

I am struggling with the end of my proof.   So far I have used the fact that $S_n=\langle T\rangle$ where $T=\{(i\text{ }j)|1\leq i<j\leq n\}$ to show that $S_n$ is generated by the set $\{(1\text{ }2),(1\text{ }3),\cdots,(1\text{ }n)\}$ of $n-1$ transpositions.   I am struggling with proving that $S_n$ is also generated by the set $\{(1\text{ }2),(2\text{ }3),\cdots,(n-1\text{ }n)\}$ of $n-1$ transpositions. Essentially I want to show that each $(1\text{ }i)$ is a product of these transpositions to reach this conclusion.   Here is what I have so far...    Consider any $(1\text{ }i)$ transposition in $S_n$. Notice by the composition of a permutation that \begin{eqnarray*} (1\text{ }i-1)(i-1\text{ }i)(1\text{ }i-1)&=&\begin{bmatrix}     1       & i-1 & i   \\     i-1       & 1 & i    \end{bmatrix} \begin{bmatrix}     1       & i-1 & i   \\    1       & i & i-1  \end{bmatrix} \begin{bmatrix}    1       & i-1 & i   \\     i-1       & 1 & i \end{bmatrix}\\ &=& \begin{bmatrix}     1       & i-1 & i   \\     i-1       & 1 & i    \end{bmatrix} \begin{bmatrix}    1       & i-1 & i   \\     i       & 1 & i-1 \end{bmatrix}\\ &=& \begin{bmatrix}    1       & i-1 & i   \\     i       & i-1 & 1 \end{bmatrix}\\ &=& (1\text{ }i) \end{eqnarray*}  Now we want to use this property, call it STAR, to show that $S_n$ is also generated by the set  $$Y=\{(1\text{ }2),(2\text{ }3),\cdots,(n-1\text{ }n)\}$$ of $n-1$ transpositions. Notice for each $(i\text{ }j)$ in $Y$ that $j-i=1$. Suppose $n=2$. Then $S_2=\{(1),(1\text{ }2)\}$, and we done because $2-1=1$. Suppose $n=3$. Then $S_3$ is generated by the set $\{(1\text{ }2),(1\text{ }3)\}$. By STAR,  $$ (1\text{ }3)=(1\text{ }2)(2\text{ }3)(1\text{ }2) $$ $$ (1\text{ }2)=(1\text{ }1)(1\text{ }2)(1\text{ }1) = (1\text{ }2) $$ Therefore $S_3$ is generated by $\{(1\text{ }2),(2\text{ }3)\}$ and for each $(i\text{ }j)$ we have $j-i=1$.    And here is where I am struggling. I do not know how to apply induction to this. I want to show that each side part will continue breaking down using the property I stated until all of $S_n$ is created. Here is why I think this: $$ (1\text{ }1)(1\text{ }2)(1\text{ }1)=(1\text{ }2) $$ $$ (1\text{ }2)(2\text{ }3)(1\text{ }2)=(1\text{ }3) $$ $$ \cdots $$ $$ (1\text{ }n-1)(n-1\text{ } n)(1\text{ } n-1)=(1\text{ }n) $$ Any input would be much appreciated. Best.


What is the difference between JAVA Runnable class to start thread?

The difference between mode 1 and mode 2 start thread? Method 1: I use the same Runnable object to start multiple threads Method 2: I use different Runnable objects to start multiple threads package com.hbase.a;  public class MyThreadB implements Runnable {     private  int tik = 100;      public void run() {        //do ...     }        public static void main(String[] args) {         // method-1          MyThreadB myThreadB = new MyThreadB();         new Thread(myThreadB).start();         new Thread(myThreadB).start();         new Thread(myThreadB).start();         new Thread(myThreadB).start();                 // method -2          new Thread(new MyThreadB()).start();         new Thread(new MyThreadB()).start();         new Thread(new MyThreadB()).start();         new Thread(new MyThreadB()).start();      } }


any knows where do i get this tool from?

Anyone knows where to get this tool Go2Shell from? Needed for App installation:


Can you get a Mathematics PhD if you're an engineer?

I'm a Software Engineering and Mathematics student. And I'll probably get my engineering degree much sooner than my Maths degree (I'm not sure I'll get it, but I'll try, as Eng. takes a lot of time off my day).  So, my question is pretty simple: Can an engineer get a Maths doctorate?  For further details, my engineering course has pretty basic maths stuff: Calculus, a bit of logic, introductory number theory, graph theory, some numerical analysis, etc.  However, I'm enrolled in a pure maths course which covers pretty 'advanced' stuff, will it matter that I passed these subjects even if I don't get my math degree?  E: Please consider reopening this question, I've added details that may be relevant to this particular scenario.


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I am using ArcGIS 10.2.2 for Desktop and I need to print\export individual maps of some 300 point Shape\layers (plant occurrences) to PDF (or JPG). Basemap extent remains fixed. Naming each Map with the Shape Name (spp. name) and text box of spp. name.   Are there ESRI solutions to this, or will this need a Python script?   At first was thinking Data Driven Pages would help; not sure now (looks like that'll do multiple regions of the same layout).


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The master bedroom and middle bedroom of my 3 bedroom mobile home is without power. None of the breakers have flipped. I even changed the breaker that controls that part of the house and my ceiling fan in my living room. Still nothing in those listed bedrooms, but the ceiling fan is working fine and I'm getting 115 VAC to the breaker. I was thinking it could be a short to one of the plugs in the middle room. It was working fine earlier in the morning. I went into the middle room to turn on an electric heater and everything went dark. I changed the plug and still nothing.  What should I do now?


Can someone with ONE minecraft account and two computes play together?

I have a friend who really likes the Minecraft PC version , but I want to play with on 2 computers, CAN I DO IT?


What is the difference between apt and dpkg?

This is probably a dumb question--I'm pretty new to Linux, so I apologize in advance. Doing some research for a gestures app, I discovered libinput-gestures.  suggests that it is compatible with Ubuntu 20.04. I know that I had installed something similar, and now I want to check if that was the one I had installed. With that background, I did some investigating into how to check if packages are installed. I found apt list --installed and dpkg --list. I know that if I filter down to apt list --installed | grep lib I do see a couple of lib-type packages, as does dkpg --list | grep libinput. My question is twofold--what are these two package managers used for (clearly they serve different purposes, but  suggests that the two operate together in some capacity), and how do I know where to search for a package like libinput-gestures?


tail -f, but when the file is deleted and re-created (not appended)

I'm trying to watch for any new output of a log file. Another script (not under my control) is deleting the file then creating a new one with the same name. Using tail -f doesn't work because the file is being deleted.


My electron Apps show "NORMAL" in top right

I use some electron apps, like every body, and i have a pixel "NORMAL" on top right corner of some of Apps, and inside menu of menubar. Screens of apps with NORMAL:      I start an Electron Apps project last year (for testing), so i have some electron dependences for development. I have Electron Fiddle. Electron Fiddle is a Electron Apps and he doesn't have "NORMAL", same for the default hello world apps of Electron Fiddle. Screens of apps without NORMAL:     Some info about my env:  Ubuntu 20.10 GNOME 3.38.1 X11  I use same apps on Windows 10, and didn't have any "normal". Any idea ? ANSWER: @RayWu said in  :  Spotify is not an electron app, it is a CEF app. Do you have any kind of GPU overlay enabled?  After this I look for NVIDIA Settings displaying "normal" and found this  Works for me, this is fixed, thanks :)


pipe entire directory of image files into ffmpeg on Windows 10 to make mp.4

I have a directory of jpgs with filenames in the following format: 2020-06-01-000533.jpg 2020-06-01-001528.jpg 2020-06-01-002532.jpg ... 2020-060390235533.jpg  I don't want to rename them because these filenames are useful for other aspects of this use case. I would like to run the following ffmpeg command on these files in order to create an MP4 from them: ffmpeg -i <this directory of files> -r 24 -c:v libx264 -pix_fmt yuvj420p output.mp4  I've seen solutions in StackExchange that recommend using glob, but that doesn't work on Windows 10.


This is going to sound like a stupid question, but I cannot understand how I get this result (I understand why, but it looks like there is no relation).  $p, q$ primes  why do we have this?  $p \cdot (p^{-1} \mod q) + q \cdot (q^{-1} \mod p) = pq + 1$  I don't see the relation between the left and right side, but still it works.


How to make sure browsers load the most recent version of a file after updating?

When rolling out a new website change or web application change, sometimes browsers load old javascript or image files when you navigate to the site. Oftentimes it takes a manual refresh of the page for the browser to load in the newly updated files.  How can I make sure that after an update, users receive the most up-to-date files the first time they load the page, rather than having to manually refresh to clear out any cached files. Is there a very reliable way to do this through sending expires headers or last modified?


I have successfully found out how to add space between entries in the list of contents, but how can I make it work with the lists of figures ad tables?    \documentclass{report} \usepackage[a4paper,bindingoffset=0.5cm, left=2.6cm,right=2.6cm,top=2.6cm,bottom=3cm, footskip=.67cm]{geometry}  \usepackage{etoolbox} \preto\chapter{%     \ifnum\value{chapter}=0\addtocontents{toc}{\vskip0.1pt}\fi     }  %\preto\figure{% %   \ifnum\value{figure}=0\addtocontents{lof}{\vskip10pt}\fi %} \usepackage{longtable} \usepackage{graphicx} \usepackage{float}  \begin{document}  \tableofcontents  \begingroup \let\cleardoublepage\relax \let\clearpage\relax \listoffigures \listoftables \endgroup  \section{Prologue} \section{Acknowledgements} \section{Abstract} \section{Introduction}  \begin{figure}[H]     \centering     \includegraphics[scale=0.5]{gfx/no-cloud}     \caption{There is no cloud} \end{figure}  \section{Theoretical framework}  \begin{figure}[H]     \centering     \includegraphics[scale=0.7]{gfx/lb-stick}     \caption{Libreboot sticker} \end{figure}  \begin{figure}[H]     \centering     \includegraphics[scale=0.6]{gfx/Trisquel}     \caption{Fully free GNU/linux} \end{figure}  \begin{figure}[H]     \centering     \includegraphics[scale=0.6]{gfx/TEX}     \caption{tex.stackexchange.com} \end{figure}   \setcounter{table}{0} \begin{longtable}[H]{c c}     Q & A  \\     \hline     ? & !\\     \caption{Q\&A} \end{longtable}   \begin{longtable}[H]{l r}     1& 2\\     \caption{Numbers} \end{longtable}  \end{document}   ----------  \documentclass{report} \usepackage[a4paper,bindingoffset=0.5cm, left=2.6cm,right=2.6cm,top=2.6cm,bottom=3cm, footskip=.67cm]{geometry}  \usepackage{etoolbox} \preto\chapter{%     \ifnum\value{chapter}=0\addtocontents{toc}{\vskip0.1pt}\fi     }  %\preto\figure{% %   \ifnum\value{figure}=0\addtocontents{lof}{\vskip10pt}\fi %} \usepackage{longtable} \usepackage{graphicx} \usepackage{float}  \begin{document}  \tableofcontents  \begingroup \let\cleardoublepage\relax \let\clearpage\relax \listoffigures \listoftables \endgroup  \section{Prologue} \section{Acknowledgements} \section{Abstract} \section{Introduction}  \begin{figure}[H]     \centering     \includegraphics[scale=0.5]{gfx/no-cloud}     \caption{There is no cloud} \end{figure}  \section{Theoretical framework}  \begin{figure}[H]     \centering     \includegraphics[scale=0.7]{gfx/lb-stick}     \caption{Libreboot sticker} \end{figure}  \begin{figure}[H]     \centering     \includegraphics[scale=0.6]{gfx/Trisquel}     \caption{Fully free GNU/linux} \end{figure}  \begin{figure}[H]     \centering     \includegraphics[scale=0.6]{gfx/TEX}     \caption{tex.stackexchange.com} \end{figure}   \setcounter{table}{0} \begin{longtable}[H]{c c}     Q & A  \\     \hline     ? & !\\     \caption{Q\&A} \end{longtable}   \begin{longtable}[H]{l r}     1& 2\\     \caption{Numbers} \end{longtable}  \end{document}


Given $P$ idempotent, show that $I-P$ is idempotent.

As title, given $V$ as a finite dimensional vector space over $F$. Suppose the linear transformation $P: V \rightarrow V$ is idempotent. I need to show that $I-P$ is idempotent.  I know that a matrix is idempotent if $P^2=P$, and that $P$ must be a square matrix.  So I need to show that $(I-P)^2 = (I-P)$? I don't have a clue on how I should proceed.   Thanks in advance!


Solve the SDE $dX_t=\alpha \,dt + \sigma X_t \,dB_t$, $X_0=x_0$

So I got the following SDE to solve:  $$dX_t=\alpha\, dt + \sigma X_t \,dB_t, X_0=x_0$$  This is what I've tried:  Using Ito's I should get the following relations:  $$X_t=f(s,x)$$ $$\alpha = \frac{1}{2}\frac{d^2f}{dx^2}+\frac{df}{ds}$$ $$\sigma X_t=\frac{df}{dx}$$  The second equation, which seems to be a ODE:  $$\frac{df}{dx}-\sigma X_t=\frac{df}{dx}-\sigma f=0$$ Using the integrating factor: $$I = e^{\int -\sigma \,dx}=e^{-\sigma x + g(s)}$$ $$\frac{df}{dx}I-\sigma fI=0$$ $$(fI)'=0$$ $$f=CI^{-1}$$ Using the initial value: $$f(0,0)=x_0=C$$ $$f=x_0e^{-\sigma x + g(s)}$$ The problem for me is now to solve $g(s)$.  Differentiating by $x$ twice and $s$ once gives: $$\frac{df}{ds}=g'(s)f$$ $$\frac{d^2f}{dx^2}=\sigma^2f$$ $$\alpha = \frac{1}{2}\frac{d^2f}{dx^2}+\frac{df}{ds}$$ $$\frac{1}{2}\sigma^2f+g'(s)f=\alpha$$  At this point I'm quite unsure on what to do.


Possible Duplicate:          My question is in the Title.  How do I get to Terminal in Ubuntu 12.04 ?


Been trying over and over, but nothing happens. Tried reinstalling Steam along with Ubuntu but that didn't do anything either. Tried other forums with helpful tips but no good. I'm running out of ideas and I don't know what else I can do. Can someone please help me before I start pulling my hair out? I'm going mad.


Sharepoint Framework for Sharepoint 2013

I know the new SPFx will be released for Sharepoint 2016 sometime in the year 2017. But are there any plans to also bring this for Sharepoint 2013?  Are there any possibilities/hacks to add a Sharepoint app created with SPFx in the Sharepoint 2013 app catalog?


First, some background.  For the sake of argument, since as far as I know from Canon, there are no limits on the distance a portkey can take you, if you knew from Muggle sources what space was like, could you devise a way to portkey to another solar body?  For example, let's look at Neptune's system. The only activity there was basically what we learned on the Voyager 2 flyby in 1989, and since, there hasn't been any more Muggle exploration, and neither are there plans to.  For a particularly enterprising Witch or Wizard, what's stopping them from taking a portkey out to Triton or Nereid? Presumably there are enough applicable charms to keep the explorers safe (the bubblehead and warming charms could conceivably allow them to breathe and stay comfortable in the hostile environments, and I assume there are spells or charms to allow physical constructs for protection and/or travel - transfiguration, for example).  The basics:  In Canon, the requirements for international portkeys are the consent of the authorised person or people within the governing bodies of both the source and destination (example: France and England in the case of Arthur meeting Bill and Fleur). However, in Quiddich Through The Ages, there is a note about referee tampering in which at least one unlucky sap had his broom turned into a portkey which dumped him in the middle of the Sahara. However, going off-planet involves going somewhere without a (human) governing body to authorize incoming travellers, so I assume the same rules wouldn't apply, though I imagine there would still be some bureaucratic involvement from the local authorities prior to departure.  So from a strictly theoretical point or view, is it plausible? Could it be done? And if so, why hasn't it?   Having read the other "Wizards In Space" questions, I don't see the answers I'm looking for. The other questions don't address the plausibility of using spells and portkeys for extra-planetary exploration and instead only rule out apparition and brooms.  For the sake of argument, would it also be (theoretically) possible to add an extra-planetary location to the Floo Net (once you get there, that is, presumably by portkey)?


What happened to the Stack Exchange Store?

There used to be a place where you could buy Stack Exchange branded gear, what happened to it?


"There must be some kind of story or legend behind it[=entrance   stone]. Maybe it's famous and on display at a shrine or   someplace." "It could be, I suppose." "Or maybe it's just in   some house, and people use it as a weight when they make pickles."   "No, that's not possible." "Why not?" "Because nobody can   move the stone." "Nobody except you, you mean." "Yes, I   think Nakata probably can." "After you move it, then what?"   Nakata did an uncharacteristic thing––he pondered this for a good long   time. At least he looked like he was, briskly rubbing his short,   salt-and-pepper hair. "I don't really know about that," he   finally said. "All I know is it's about time somebody moved   it." Hoshino did some pondering himself. "And that somebody's   you, right? At least for now." (Kafka on the Shore, tr. by Philip   Gabriel)   Why is moved a past form; is it a kind of subjunctive?


A problem involving ideals and prime ideals.

Please help me with a solution to this problem.  Let $R$ be a commutative ring. Let $A_1, A_2$ be two ideals of $R$, and $P_1, P_2$ two prime ideals of $R$.  Assume that $A_1 \cap A_2 \subseteq  P_1 \cap P_2$. Show that there exist $i, j \in \{1,2\}$ such that $A_i \subseteq P_j$.


How can I call this argument using the regex test method?

It seems like you cant call an argument in your regex expression. Is there such a way? I want it to return true if the key search is in the string. function sequenceSearch(str, key) {   console.log(/key/g.test(str)); } console.log(sequenceSearch('arcata', 'cat')); //true


What is the exact definition of unknotted spanning arc?

I've just studied "An introduction to knot theory" by W. B. R. Lickorish. On page 4, to define the sum of two knots $K_1$ and $K_2$, he has mentioned the following sentence: "regarded $K_1$ and $K_2$ as being in distinct copies of $S^3$, remove from each $S^3$ a ball that meets the given knot in an unknotted spanning arc ..." I have two questions: 1-What does it mean by a ball that meets the knot in an unknotted spanning arc? 2-What is the exact definition of an unknotted spanning arc? I(think) know what is intuitive behind it, But I want to know the formal definition.


How to change white background of an gif image to transparent

I have an gif Image like example    and I want to make its background transparent from white. I am an learner of Photoshop so please describe steps to do it. Currently I was trying to edit each and every layer of this image but its really tough to go through all the layers and I am sure there is an easier way for it


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Insufficient Power when using one power source vs two

So I've been working on a wireless remote relay switch using several components and have struck a break wall. The issue I'm having is that the D0 siginal output triggers the relay but only at short range. When using 2 different power sources the relay behaves as it should with pretty good distance.  Basically the issue I think I'm having is related to a power one which is beyond me and hopefully someone can guide me in the right direction.  Below is the some details of each main component:   315mhz SC2272-M4 Receiver (5v) 315mhz 4-CH SC2262 Transmitter (12v) High & Low Level SRD-05VDC-SL-C Relay circuit for Uno 3 (5v)   Here's what I've tried.         – Schematic created using   Basically what I'm finding is that D0 is dropping mA and not driving the high level trigger, but it works fine with its own power source, something I hoped to correct by using a 1AMP+ Mains USB supply. Is there a better way to resolve this issue. Oh, I've also messaged the seller of the high low level trigger relays to find out the exact mA at which the low and high triggers trigger on.  Updated:  As recommended I have tested the circuit with a multimeter and here's what I've discovered.  When activating relay:   Data 0 (DCA - 20m) drops from 8.70 to 7.75 (very unstable sometimes can drop as low as 1.0) Data 0 (DCV 5v) drops from 5v to 4.3v (very unstable when range is increased, as low as 0.33v)


Is there a way to enable Two-factor authentication for my apple id without any physical device?

Apple has stopped publishing my apps in appstore, because my appleId has to be enabled with "Two-factor authentication" first. Now I have no MAC nor any iOS Phone / Tablet anymore.  How can I enable "Two-factor authentication" without to be bounded to any physical device. I can still manage the disabled apps in "Apple Store Connect", but I am forced to enable "Two-factor authentication".


How can I handle two separate file part as one (mount, virtual join, etc)?

I have tried to download a 8GB ISO image file. Unfortunately the file system was FAT32 on the pendrive. Max file size was only 4GB. The download process was aborted at a point, but as I used wget for download, I got a partial file. Then I examined the incomplete file, for its size, and I continued the download with cURL, explicitely defining the byte range. After successful download I have two separate file parts. Question is, how can I handle them as one: some kind of virtual join, or kind of mount, without copying them really together. I have no free space for phisically joining them on hard disk, this is why I downloaded them onto a 16 GB FAT32 pendrive.


stackexchange site in other language for specific communities networks

Is it possible to have a stackexchange site for some specific community in the local language of the country ?  For example, in my country, if I want to use the stackexchange to create some network community (social, education, etc), free and useful for the population, in the local language.  What are the possible solution ? customisation, collaboration, ... ?  Thanks & Regards.


Why are coke bottles that much fizzier if you shake them?

We've all been there: you drop your bottle of soda at some point and when you try to open it, it bursts into foam. My question is, then: why does shaking a carbonated drink make the dissolved gas escape?


Name list replaced by dash in bibliography

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I am preparing response to comments given by the reviewers for my thesis. I wrote each of their comment as a question using exam document class. For giving response to their comments I am using answer option. So the format is somewhat like this:   \documentclass[answers]{exam} \begin{document} \section{First Reviewer Comments}     \begin{questions}     \question First comment.     \begin{solution}     My response.     \end{solution}     \end{questions} \end{document}   It prints [Solution: My response] inside a box. I want to replace "Solution" by "Response". How to do this ?


When I punch a wall, Why doesnt my fist go through instead of staying at rest on the wall? What is cancelling out the force of my punch?


Does network interface device have device inodes

Does network devices have device nodes because i have looked inside /dev directory and have not found any corresponding device node although it's up and running


I am new to using Linux, I have always used Windows in the past. My question is regarding the Ubuntu Software station where you can download new software and stuff. I have yet to try to download anything, but when I have tried deleting certain programs it doesn't always work. Half the time I click "Installed" or "Updates" at the top it just continuously loads and goes nowhere. I have yet to be able to access the updates tab but I can see I have 14 available updates. When I have tried deleting programs they sometimes actually are deleted, but sometimes it just says removing and never changes, or it will finish but once I close the Ubuntu software program and return to it, the program I deleted is once again under the "Installed" tab. I am decent with computers but by no means a programmer or anything, I have never used anything like Terminal so any options with that will only get me lost, although I do hope to become better with Terminal.  Any tips or tricks to get the Ubuntu Software "Store" to work properly?


Bijection between [a,b) and [a,b] intervals.

I need help with finding a bijection between these two intervals: [a,b) and [a,b]. It is told that a,b are in R (real numbers). I know how to construct a bijection if a,b are integers, but i have no idea how to do it if they are real. Any ideas?  Edit: If anyone is still watching, can you tell me if I'm doing this right?  So the bijection will be f(x) = 1) a if x = a and 2) b/p-1 if x != a and x = b/p , where p is in R - {0}.  By taking the p from R - {0} and not from N, I think this could work for real numbers.  Because a < b, every number from a to b can be written as b/p. So the function moves every number upwards if I express myself that way, thus reaching the b.


Say I have the following key-value file I want to highlight using the listings package:  some.key=Some value   I want the key to be red, the equal sign to be black and the value to be blue. How do I define a language in listings that does that? I am aware of the moredelim, morekeywords but I can't figure out how to use their options to do what I want.


I've taken a screenshot, how do I edit it?

I'm used to taking screenshots in Windows and then editing them before posting them (with MSPaint)  How can I edit a simple image quickly on OSX?    I took a picture of a P.O. and I want to remove any PII information


Unable to use Gparted on 17.10. I have already tried "sudo xauth merge $HOME/.Xauthority" and with gksu and gksudo. Gksudo has another issue in Ubuntu 17.10. I am unable to enter password in the prompt that appears.


Which facility upgrade unlocks maneuver nodes in KSP

Which  unlocks  in career mode in KSP?  The  hints that maneuver nodes are now unlocked with a facility upgrade:     Are there any perks for upgrading?      The building in question   will upgrade visually, both from the outside and the inside. More   gameplay mechanics will be also be unlocked as the player progresses   through the different building tiers. For example, allowing EVAs in   space or being able to use maneuver nodes in the map view.


The roots of transcendent equation $\tan(x)=x$

Can we find the roots of equation $\tan(x)=x$.    I once found a formula which gives its roots approximately. Any link will be wlecomed.


How to download/install/configure a pre-installed Ubuntu image

I'm planning on buying a Dell with pre-installed Ubuntu image.  In case something goes wrong, how do I reinstall Ubuntu from scratch with the Dell's image containing all of Dell's specific drivers?   I couldn't even find a downloadable image on  :-(


I have linked a new USB drive with my system and i am not able to copy any file to it. I tried to change the permission by using below command:  /media$ sudo chmod 777 0000-7D6C   "0000-7D6C" is the drive name. But it gives below message:  chmod: changing permissions of `0000-7D6C': Read-only file system   Can anybody help me please.


Problem in figure environment in article

\documentclass{article} \usepackage{graphicx,amsmath,tikz} \begin{document}  \begin{figure} \includegraphics{1.2.jpg} \caption{d} \end{figure} \end{document}   By using the above code I am getting the following error..     Unknown graphics extension: .2.jpg. \includegraphics{1.2.jpg}   How to fix that??


Show that $\lim_{n \to \infty} \frac{1}{\sqrt{n}} \int_{[0,1]^n} |x|dx= \frac{1}{\sqrt3}\space $

Let $(\Omega, \mathcal{M}, \mu)$ be a measure space, $E \subset \Omega$ and $f: \Omega \to \mathbb{R}$ are measurable. Let $E_t= \{x \in E \space | \space |f(x)| \geq t \}$ for $p>0$. I already showed that for $p>0$: $$\mu(E_t) \leq \frac{1}{t^p} \int_E |f|^pd \mu \space .$$ Now I want to show that  $$\lim_{n \to \infty} \frac{1}{\sqrt{n}} \int_{[0,1]^n} |x|dx= \frac{1}{\sqrt3}\space .$$ $[0,1]^n \subset \mathbb{R}^n$ is the unit-cube, $|x|$ is the euclidean norm and the integration is with the Lebesgue measure in $\mathbb{R}^n$.  I was told that the first step is to show $$\lambda(E_t) \leq \frac{1}{n} \frac{A}{t^2}$$ with using the Lebesgue measure in $\mathbb{R}^n$, with $t>0$, $p=2$, $E=[0,1]^n$ and $f(x)=\frac{|x|^2}{n}-\frac{1}{3}=\frac{1}{n}\sum_{k=1}^n(x^2_k-\frac{1}{3})$ for $A>0$. How do I do that? $i \neq j: \int_E (x_i^2-\frac{1}{3})(x_j^2-\frac{1}{3})dx$ and $|\int_E \frac{|x|}{\sqrt{n}}dx-\frac{1}{\sqrt{3}}| \leq \sqrt{3} \int_E |\frac{|x|^2}{n}-\frac{1}{3}|dx \leq \sqrt{3}(\lambda(E_t)+t\lambda(E$ \ $E_t))$ are also tips we've been given but I don't really know how to apply them.


instance of class cause nullPointerException

I am importing an Excel 2007 file with poi in Eclipse. My problem is a NullPointerException, but I have no idea how to figure out where it is coming from. Maybe something is wrong with the instance of class Data. This is the code:  import java.io.*; import java.io.*; import java.util.ArrayList;  import org.apache.poi.openxml4j.exceptions.InvalidFormatException; import org.apache.poi.ss.usermodel.Cell; import org.apache.poi.ss.usermodel.DateUtil; import org.apache.poi.ss.usermodel.Row; import org.apache.poi.ss.usermodel.Sheet; import org.apache.poi.ss.usermodel.WorkbookFactory; import org.apache.poi.ss.usermodel.Workbook; import org.apache.xmlbeans.XmlOptions;  class Data{     public Data(){};     public Data(double[] codnt, int ctgr1, int ctgr2) {     //  super();         this.codnt = codnt;         this.ctgr1 = ctgr1;         this.ctgr2 = ctgr2;     }     double codnt[];     int ctgr1;     int ctgr2;   } class Center{     public Center(int cycle, Data[] c) { //      super();         this.cycle = cycle;         this.c = c;     }     int cycle;     Data c[]; } public class KmeansCluster {     @SuppressWarnings({ "static-access", "null" })     public static void main(String[] args)throws IOException,InvalidFormatException{         InputStream is = new FileInputStream(new File("src//artificial_exp1.xlsx"));         Workbook wb = WorkbookFactory.create(is);         Sheet sheet = wb.getSheetAt(0);         ArrayList<Data> list = new ArrayList<Data>();         int i = 0;         try {             for (Row row : sheet) {                 Data dataTemp = new Data();                 // int i = 0;                 int j = 0;                 for (Cell cell : row) {                     row.getCell(0).setCellType(cell.CELL_TYPE_NUMERIC);                     dataTemp.codnt[j] = cell.getNumericCellValue();                                    j++;                     System.out.println("cell.getnumericcellvalue() is " + cell.getNumericCellValue() + "datatemp.condt[j] is " + dataTemp.codnt[j]);                     System.out.println(" test passed !");                 }                 dataTemp.ctgr1 = (int) dataTemp.codnt[j - 2];                 dataTemp.ctgr2 = (int) dataTemp.codnt[j - 1];                 list.add(dataTemp);                 i++;             }             Data data1 = (Data) list.get(0);             System.out.println(data1.codnt[0]                     + "    is the content of the first blank.");         } catch (Exception e) {             System.out.println(e.toString());         }     }  }


Why does the LM1117 data sheet specifically specify tantalum capacitors?

I'm planning on using an  to regulate 5 V to 3.3 V. Looking at (  the ) data sheets for the LM1117, they recommend 10 µF tantalum capacitors between input and ground and between output and ground.  I understand the need for the capacitors, but it's not clear to me why these should specifically be tantalum. I have a bunch of electrolytic 10 µF capacitors sitting around here, whereas if it does for some reason need to be tantalum, I'll have to order those.  Why are they so specific about using tantalum capacitors?


Are there any gay characters in Star Trek?

If you discount species that only have one gender (which are homosexual by default), and species that change their appearance or body (like Changelings and Trills), are there any homosexual characters in the prime universe?  I am aware of Ezri and Lita being homosexual or bisexual in the Mirror Universe, but I am interested in the canon prime universe.  This question is explicitly about homosexuality. I am not focusing on those who are bisexual characters (there is one, Garak) or transgender characters (there is an entire episode covering that topic.)  This is also not a question about the legal status of LGBT peoples in Star Trek - its about if there were any on screen characters who were homosexual (identified as such on screen or in the background by the actor or producers.)


A trilogy which started as fantasy but ended up as science fiction

I remember reading a trilogy of books during the '80s or '90s. I was in the USA and the books were in English. The first had the appearance of pure fantasy (and I thought it was). The second shifted pretty seamlessly to science fantasy. In the third you realized the whole story had been science fiction.  Half-remembered details include   the world being transformed or terraformed, though it was habitable to begin with people were transformed too. All men became horny, handsome, ripped hunks, while the women became over-boobed, horny bimbos. I say that because the transformation affected their minds too, not as an insult.  Even though their minds were affected, they could still strive to and succeed in think(ing) normally and rationally. ... This will sound weird, but I don't think this plot point came off as farcical. two types of mages: those who could change matter and those who would use illusions.  The illusionists might have been considered the more powerful. a realm of heavy mist or fog. The illusionists may have been strongest when there. one of the lead females unexpectedly gaining male genitalia. I think she eventually became an over-boobed bimbo too. Eventually I think she became fully female again.  Oh!! -- I think it was a switch! A guy got her crotch, and she got his. the author may have been pretty prolific at the time (multiple books per year)     (response to "duplicate" notice)   The series Soul Rider is indeed the short answer to both questions. The original question, however, provides only background information (so far as I could tell) for the first 3 volumes -- written and published as a trilogy.  Instead the question apparently concerns itself with volumes 4 and 5, which was/were prequel story(ies) published after the trilogy. From book summaries, they are science fiction telling of an interstellar human civilization and how it eventually came to found a colony on an isolated planet and begin terraforming it. The question describes them losing track of technology. The events in item 2 probably predate the trilogy by hundreds or thousands of years, with different characters. The first volume of the trilogy, where my question begins, appears as a fantasy story about a medieval civilization with magic. Over the course of the trilogy you learn more about the world, and by the third volume you realize that it has been a science fiction story all along. The questions are completely different, describing different things.  But if it is common practice in SF&F to declare::link as duplicates such questions if they have the same answer, I have no objection. Hopefully the linkage will go both ways though, so people with knowledge only of the trilogy can know about the prequels, and people who know only about the prequels can find the trilogy.   Q1: I'm looking for a series of movies about a little boy who rides a flying speed racer.  He grows up, makes friends, has adventures, and fights a lot of people. He doesn't like sand. I think he yells near the end, like he was really sad or something. But maybe he didn't. Q2: I'm looking for a series of movies, a trilogy I think, about a teenage boy. He meets some robots and an old guy, and then his parents are killed by some bad guys. He makes more friends, has adventures, and fights a lot of people. One of the bad guys can't breathe very well and wears a big helmet. Now he says he's the kid's father. In the end there is a big fight, and they blow up the really big spaceship of the bad guys. Then they do it again, this time with help from a bunch of teddy bears. Once they have answers, are Q1 and Q2 duplicates?


I was going through some articles about "African American Vernacular English". . . These articles give some examples, but they do not clearly specify hard rules to be followed in AAVE.  First of all, I don't even have strong skills in Standard English, so understanding AAVE seems a lot more difficult for me. I did, however, craft a few sentences in both SE and AAVE to validate what understanding I do have. Are the following conversions correct? You don't have to validate each and every item, but rather guide me with rules that I should follow, but didn't, in the following examples.   What the hell are you all doing here?  —  What the hell y'all doin' here? Hey you! What the hell are you doing man? Stop that nonsense now. Do you get it?  — Hey you! What the hell ya doin’ man? Stop that nonsense now. D'ya get it? Come on, can't you open your mouths?   — Come on, ya can't open your mouths??  Hey, who's out there?  —  Hey, who out there? I know, you're listening to us   — I know, ya listenin’ to us Somebody is out there man. — Somebody out there man. Wow, it's delicious.  — Wow, it delicious. Holy crap, who're these people? — Holy crap, who these people?


Is   $$S=\sum_{n=2}^{\infty} \frac{1}{(\log n)^{\log n}}$$ convergent  or divergent?   My attempt :  $(\log n)^{\log n} = \exp((\log \log n)^2) \le \exp(((\log n)^{1/2})^2) = n$ for $n \ge N_0$, so $$\sum_{n=2}^\infty \frac 1 {(\log n)^{ \log n}} \ge C + \sum_{n=N_0}^\infty \frac 1 n = \infty$$  so it  is divergent   Is its true ?


Startup Disk Creator not recognizing selected ISO in 13.10

I recently downloaded the Lubuntu 12.04 LTS ISO for Power PC (I want to install it on an old iBook G4), but when I go to select the ISO in Startup Disk Creator, it just remains blank in the Source disc image (.iso) or CD: area.   Here is the screenshot from before (and it looks the same afterwards) selecting the ISO.     As you can see, the ISO is on the desktop separate from any other ISOs, IMGs, etc.  I read this question: , but that didn't help. Neither did  or .  Two of those are 12.04 and one is 12.10, so they are both not my version, if that changes anything.  Does anyone have any clue why this is? I am going to attempt it with Unetbootin and if that fails, manually via the terminal and dd.


In the Last Jedi movie, there is a scene where      her spaceship is taken down, Princess Leia is thrown into outer space, and seen floating there, frozen.    However, she manages to survive this, while any ordinary human being couldn't.   How did she manage this? Is this done by using the Force?


prove that a graph with degree $\frac{n-1}{2}$ has a diameter of at most 2

I try to solve the following:     let $G$ be a simple graph with minimum degree of $\frac{(n-1)}{2}$ with $n$ vertices. prove that $G$ is connected and that the diameter of $G$ is at most $2$   I Know how to prove that the graph is connected -      assume that we take some connected component K, for each $v\in k$ we have that $deg(v)=\frac{n-1}{2}$ so that means that we have at least $\frac{n-1}{2}+1=\frac{n+1}{2}$ vertices which implies that if we have more then one connected component we have more than $n$ vertices - a contradiction   But  how to prove the diameter part? my way of thinking was to compute how many vertices can I reach after "two moves" trail but I got some not conclusive result:  $$\frac{n-1}{2} + \frac{n-1}{2}\cdot ( \frac{n-1}{2} -1)$$ $$\Downarrow$$  $$=\frac{(n-1)^2}{4}$$ which is not bigger than $n-1$ for all $n$ I know how to work around this but this seems "lame" I am sure there is some other elegant way.


I received call one of a company. They are implementing and installing Ubuntu Desktop OS in there client systems and they need:      Create one user as a temporary user and that user should have 3 options enabled in client system:          google chrome with one fixed URL(http:192.168.1.1)    printer access for printing    scanner access for upload docs.          All remaining functionality should be disabled.    For the above process, what resources do we have to use and how can we disable everything? The Company is asking to make a professional document for the above installation. Please help me with this issue.


Limit of the Recursive Sequence $X_1=1, X_{n+1}= \frac 1{1 + X_n}$

We have that $$ X_1 = 1, \quad X_{n+1} = \frac 1{1 + X_n}. $$ If $X_n$ has a limit find algebraically the value of the limit. The sequence goes; $$1,\frac{1}{2},\frac{3}{5},\frac{5}{8}, ...$$ The sequence appears to be converging to 0.6 as $n$ tends to infinity. May you have a say on this one. Thanks


I recently decided to watch Doctor Who, and started viewing the 2005 version. I have the first two episodes from the first season, and I can't help but wonder what is the etymology of the name "Doctor Who"? And why does the protagonist call himself "the Doctor" (or is it "the doctor")?


The operator == is undefined for the arguments type bool

Could anyone help me with that? I get the error stated with the following code:    if (actualStep.getChanged() == null) {         notificationCombo.setItems(FXCollections.observableArrayList("There are no new changes."));         notification.setImage(notificationBLUE);     }   I get a Nullpointer when compiling as the boolean is not inizalized.


If $A$ and $B$ are Positive semidefinite matrices, then $\operatorname{Col}(A B) \cap N u l l(A B)=$ $\{0\}$ .

If $A$ and $B$ are Positive semidefinite matrices, then show that $\operatorname{Col}(A B) \cap \text{Null}(A B)=$ $\{0\} $. From this, I have been able to show that eigenvalues of $AB$ are non-negative. I tried to show that the Null space of $AB$ and $(AB)^2$ are equal for proving the required statement, but I could not show so. How can we approach this problem?


Find all primes that can be represented by $n^3+1$, $n\in \Bbb N$.   This is a problem from a math olympiad contest, no answer provided.   For sure 2 is one of them (when $n=1$), are there others?


Leaflet markers from CSV with multiple columns employing omnivore

Goal: Show markers for lat-lon positions from a CSV file. The other columns need to be placed in pop-up as attributes.  CSV file can be seen at:   Code:  headers = ['iata', 'title', 'city', 'state', 'country'] // determined programmatically and excludes latitude longitude  customLayerLocalData = L.geoJson(null, {     onEachFeature: function (feature, layer) {         var popupContent = '';         $.each(headers, function (h) {             popupContent += feature.properties + '.' + headers[h];             if (h != headers.length - 1) {                 popupContent += '+'             };          });         layer.bindPopup(popupContent);     },     pointToLayer: function (feature, latlng) {         return L.circleMarker(latlng, customMarkerOptions);     } }); layerLocalData = omnivore.csv.parse(fr.result, null, customLayerLocalData).addTo(map);   Problem: The pop-up shows the object:   [object Object].iata +[object Object].title +[object Object].city +[object Object].state +[object Object].country   If I change: layer.bindPopup(popup content); to layer.bindPopup(eval(popup content));, it works. But, I am not happy with this solution (does not feel right). Morever, in this case new lines can't be inserted inside the custom geoJSON layer.  I'm looking for a smarter solution that can interpret the 'popupContent' and pass onto to layer.bindPopup correctly.


I want to install PSTricks (I use Texmaker). I have downloaded the files from the following page:  but nowhere do they say where the files should be copied or how the package should be installed. Can someone help me? I am new to latex.  This is what i get :  ! Undefined control sequence. <recently read> \c@lor@to@ps l.142 ...ddiv=0,gridlabels=0](0,0)(-16,-12)(13,24) The control sequence at the end of the top line of your error message was never \def'ed. If you have misspelled it (e.g., `\hobx'), type `I' and the correct spelling (e.g., `I\hbox'). Otherwise just continue, and I'll forget about whatever was undefined. ! Undefined control sequence. \XC@usec@lor ...string \color@ #1#2\endcsname \@@ \fi \space l.142 ...ddiv=0,gridlabels=0](0,0)(-16,-12)(13,24) The control sequence at the end of the top line of your error message was never \def'ed. If you have misspelled it (e.g., `\hobx'), type `I' and the correct spelling (e.g., `I\hbox'). Otherwise just continue, and I'll forget about whatever was undefined.


Does quantum chromodynamics imply continuous space?

I am thinking it does.  That's because a pillar of quantum chromodynamics is renormalization, which is itself due to the assumption that electrons are point particles (having no extent).  A point particle has no place in a discrete universe, as it wouldn't exist at all.  This question is asking the specific question about renormalization and the assumptions of electron radius, and just the broad issue of quantum mechanics itself.


I want to delete the paragraph that jquery create when I click the paragraph.
cutsom event
 <button class="clcik">click</button>   jquery:  $(function () { "use strict";  $(".test").on("click", function () {     $(this).hide(); });  $("button").on("click", function () {     $("
delet this paragraph
").insertAfter($(this)); });  $("p").on("click", function () {     (this).hide(); }); });   update: @LinkinTED solved it, but dose there best practice for for that code?


Limit of the sequence $\lim_{n\rightarrow\infty}\sqrt[n]n$

Possible Duplicate:          I know that   $$\lim_{n\rightarrow\infty}\sqrt[n]n=1$$  and I can imagine that $n$ grows linearly while $n$th root compresses it exponentially and therefore the result is $1$, but how do I calculate it?


The description for Hat Trick is:     hit the reputation cap on three different days   First of all, I'm not complaining :)  I received this hat (hard to say "earned") a couple of hours ago, without actually reaching 200 (yet).


unable to open ubuntu in Oracle VM Virtual box

When i start the Ubuntu in Oracle VM Virtual box, it throws following error.   This kernel requires an x86-64 CPU,but only detected an i686 CPU. Unable to boot- Please use a kernel, appropriate to your CPU.   Kindly lend your help to overcome this issue.


What does dash "-" mean in Unix command line?

Given this diff command:     ./a.out < 1.in | diff - 1.out     What does - mean after the word diff? Thanks for the help!


A regular polygon $\mathcal{P}$ is inscribed in a circle $\Gamma$. Let $A$, $B$, and $C$ be three consecutive vertices of the polygon $\mathcal{P}$, and let $M$ be a point on the arc $AC$ of $\Gamma$ that does not contain $B$. Prove that $MA \cdot MC = MB^2 - AB^2.$  I have tried inscribing the polygon in a unit circle with no luck.  Any help is greatly appreciated!


I've just started learning Java, when trying to compile the below source code using "Javac" I am getting the following error:  "C:\Java>javac 99Bottles.java  99Bottles.java:1: error:  expected  public class 99Bottles { //open Class "99Bottles"  Can't seem to figure out if this is a syntax error or if i'm missing something? Any advice would be greatly appreciated, thanks    public class 99Bottles { //open Class "99Bottles"     public static void main (String[] args) { //Open main method         int Beernum = 99; //delcate intergar called "Beernum" with value of 99         String word = "bottles"; //delcare the string "word" with a value of "bottles"          System.out.println(Beernum + " " + word + "of beer on the walL");  //prints         System.out.println(Beernum + " " + word + "of beer"); //prints         System.out.println("you take one down"); //prints         System.out.println("you pass it around"); //prints          Beernum = Beernum - 1; //subtract 1 from the value of "Beernum"          if (Beernum > 0) { //Check if Beernum is greater than 0                 System.out.println(Beernum + " " + "of beer on the wall"); //prints         } else { //if the if statement is not true run this                 System.out.println("no more bottles of beer on the wall"); //prints             }              } }


How do I extend ext4 partition using GParted?

I don't know how to extend partition sda6 (ext4) with the unallocated space 265.54 gib


how to get texures with models from 3ds max into blender

so I recently found out how to rip game models from a game, thing is for the texures to come with them I had to texture them in 3ds max. I use blender to animate so I was wondering if there was a way, if any to get the model from 3ds max with the textures on it. I tried doing it a few different ways but the texures were all messed up when i put them on the model. any ideas?  before you mark as a duplicate I know how to get the model in blender, I do not know how to make the textures correct on the model once it's in blender


Using Firefox's "awesome" bar to search strings with periods?

I was a Google Chrome user for a while, and that browser was pretty smart about figuring out whether something is a domain name (e.g. date.com) or something I want to google for (e.g. DateTime.Parse).  Firefox, on the other hand, always tries to resolve strings that contain periods as domain names, even if it makes no sense (".parse" is not an allowed top-level domain at the moment).  Can I somehow configure it to be smarter about it?  Addendum: Yes, I know that Firefox has a dedicated search box for search queries; I just don't want to make that little bit of mental effort every time I need something online.


"GPG Error: Clearsigned file isn't valid" When Installing Mongodb

I am trying to install mongodb using .  I get to the step where you do sudo apt-get update and most of this runs just fine until I get the error as follows.  E: GPG error: http://downlaods-distro.mongodb.org dist InRelease:   Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)   This means I can't continue with the installation. Is there any way I can fix this? I am completely lost.


I am doing some multivariate regression. When I plot QQnorms to check my model assumptions (errors normally distributed), I get   Question: How do you interpret the above? Are the normality assumptions completely off? What's with those "breaks" near the ends of some of the plots? Is this caused by outliers?


Every $n\times n$ matrix is the sum of a diagonalizable matrix and a nilpotent matrix.

I would like to prove that every $n\times n$ matrix is the sum of a diagonalizable matrix and a nilpotent matrix. How is this possible? I'm not sure where to begin really- I know that a nilpotent matrix is one of which some power is the zero matrix.  I also know that a matrix A can be written as $AP=PJ$ with $P$ invertible and $J$ of Jordan form.  I have proven that any strictly upper triangular matrix is nilpotent, so $J$ can be written as $D+N $, with D diagonal and $N$ nilpotent, but how can I change this for A? Thank you!


How to stop gdalwarp creating world-spanning outputs near the dateline?

I'm using gdalwarp to manipulate SRTM tiles near the the dateline (i.e. 180°, aka the antimeridian). SRTM tiles have a very slight (1/2 pixel) overlap with the meridian. You can see this using gdalinfo:  gdalinfo S16W180.hgt Driver: SRTMHGT/SRTMHGT File Format Files: S16W180.hgt Size is 1201, 1201 [...] Lower Left  (-180.0004167, -16.0004167) (180d 0' 1.50"W, 16d 0' 1.50"S) Upper Right (-178.9995833, -14.9995833) (178d59'58.50"W, 14d59'58.50"S) [...]   So the source spans the dateline by a tiny amount.  This causes problems with gdalwarp, which ends up creating huge globe-spanning outputs.  gdalwarp -t_srs "epsg:900913" S16W180.hgt test.tif gdalinfo test.tif Driver: GTiff/GeoTIFF Files: test.tif Size is 1703, 5 [...] Lower Left  (-20037508.330,-1806798.473) (180d 0' 0.00"W, 16d 7'13.00"S) Upper Right (20032839.451,-1689152.120) (179d57'29.01"E, 15d 5'45.84"S)   Note the longitudes span (almost) the entire globe, and also the number of lines is unexpectedly small (5)  Is this a bug in gdalwarp? If not, what are the correct options to pass to gdalwarp to get a sensible output?


How to create a rounded edges like this In Illustrator CS6 (Example included)

Sorry for such a newbie question. I tried google but can't find anything similar. I'm using Illustrator CS6 so I don't have CC's rounded corner tool. I tried Effects > Stylize > Round Corners but it doesn't work.  Here's what happens: (as you can see it distorts it)    I also tried applying a stroke to circle and removing the bottom half of circle then applying rounded caps to stroke but I don't like the final result.  Here's what I want to do.   This is what i have created by manually adjusting the corners using the pen tool but it looks pretty bad.


Looking for sci-fi novel I read about humanity finding alien station on orbit of Earth

I am looking for a novel that I'd love to re-read it with my wife (my 13-year old self must be proud of me I guess). Key Plot points The plot was about humanity finding an alien station on an orbit of Earth. (I'm not sure if it wasn't Moon itself). On this station there were thousands of ships ready to travel so there rose a company that paid people to get on those ships and explore the galaxy. The problem was humans didn't understand how to steer those ships so they had to rely on preset targets. Of course there was no telling where particular ship was to go and fair amount of them never returned. Chronology and other relevant information I read it as an early teenager back in early 2000s. It was Polish translation of a foreign (possibly English) story. I think (not sure) that the book wasn't new at the time. It was just one of those books you dig out in a library and take to see if it's good. I don't recall cover either and even if I did it'd be of the Polish version. Additional information could be that the narration was led along the psychoanalytics of the main protagonists where he relives his memories from inside the station and his journeys.


I would like to better understand the gram-schmidt process. The statement of the theorem in my textbook is the following:     The Gram-Schmidt sequence $[u_1, u_2,\ldots]$ has the property that $\{u_1, u_2,\ldots, u_n\}$ is an orthonormal base for the linear span of $\{x_1, x_2, \ldots, x_k\}$ for $k\geq 1$. The formula for $\{u_1, u_2,\ldots, u_n\}$ is:   \begin{equation} x_k   = \left|\left| x_k - \sum\limits_{i<k}\langle x_k, u_i\rangle u_i \right|\right|_2^{-1} \left(x_k - \sum\limits_{i<k}\langle x_k, u_i\rangle u_i\right) \end{equation}   Note that I am primarily interested in how all of the vectors are orthogonal. The norm term in the above equation tells me that all the vectors will be unit vectors and hence we get an orthonormal set. Anyway, I see how this works algebraically; Let $v = x_k - \sum\limits_{i<k}\langle x_k, u_i\rangle u_i$. Now, take the dot product of $\langle v, u_j\rangle$ for some $j<k$: \begin{equation}   \langle v, u_j\rangle = \langle x_k, u_j\rangle - \sum\limits_{i<k}\langle x_k, u_i\rangle\langle u_i, u_j\rangle \end{equation} When we assume in the induction hypothesis that we have an orthonormal basis for $i<k$ then the sum is zero except when $i=j$. This leaves us with: \begin{equation}   \langle v, u_j\rangle = \langle x_k, u_j\rangle - \langle x_k, u_j\rangle = 0 \end{equation}  OK, I can logically follow algebra, but how can I see this geometrically? Can someone provide both 2D and 3D examples/plots? Since I am specifically interested in seeing how all the vectors meet at 90 degrees.


How does a bike's weight affect the overall experience of owning it?

Naturally, carrying a light bike up the stairs is much more enjoyable compared to a heavier bike. Are there any other aspects of a bike which are affected by its weight?  For example, would the weight affect handling at low speeds? Higher speeds? Turning? Stability in strong crosswinds, heavy rain or other adverse weather conditions?  What does the weight say about a modern bike's components? About its durability or dependability? Maintenance? Wear and tear?  Are lighter bikes always better? What would be a reasonable weight threshold below which gains are diminishing?  As an inexperienced cyclist looking for a new bike, I'm unsure how much I should be paying attention to its weight.  UPDATE: what specific weight ranges should I be looking for these days? What would be considered very heavy, reasonable, and at what weight do we enter the multi-thousand-dollar pro racing bikes?  I found a cheap made-in-China fixie in Singapore (where I live); when I learned it weighs 17kg I realized why it's so cheap!


Why didn't this character from Harry Potter become a ghost?

We know that characters in HP world become ghosts after their deaths if they were scared of death and they have chosen to die.      "I was afraid of death. I chose to remain behind. I sometimes wonder   whether I oughtn't to have… well, that is neither here nor there ...   in fact, I am neither here nor there ... I know nothing of the secrets   of death, Harry, for I chose my feeble imitation of life instead." --   Harry Potter and the Order of the Phoenix, p. 861   This seems to be the case of       Peter Pettigrew   he obviously doesn't want to die, he is scared (at the moment of his death as well as his whole life). He was a rat all his life, I would guess he would be a rat in this decision.    So did he became a ghost? If not, why?


Why if $a =b$ then $a = 0$ is not a correct statement

Bogus Claim: If $a$ and $b$ are two equal real numbers, then $a = 0$  $a = b$  $a^2 = ab$  $a^2 - b^2 = ab - b^2$  $(a-b)(a+b) = (a-b)b$  $a + b = b$  $a = 0$  I found this in my proof handouts, and correct me if I'm wrong,but is it wrong because after line 4 we divide both sides by $(a - b)$ which would be $0$ if $a = b$ ?


Store all items from filename to another then return that file

So lets say i was given a function to store whatever is in one filename to a different file name, how would i do that?  def return_newfile(self, filename):      ......     .....     ....     self.return_newfile(data)


How to evaluate "performance" of my model?

I am very new to Machine Learning, and this is my first project on which I am working. I am trying a binary classification problem, trying to predict claim(yes/no) from an insurance dataset. In my dataset, I have about 7% positive class (1534 Positive datapoints, 21076 Negative datapoints). I have 7 features (2 numerical, 5 categorical).   My model is giving the following performance metrics:               precision    recall  f1-score   support            0       0.95      0.70      0.81      6311           1       0.12      0.52      0.19       472 avg / total       0.89      0.69      0.76      6783   Being a beginner, I am having difficulty understanding how good/bad my model is based on these metrics. How much can I improve my model, given the small and highly skewed dataset which I have? I have taken the following approach: Randomly sample 50-50 splits of the data 10 times, train a Logistic Regression on each, and then average the predictions of all the 10 models.


don't get mad please as I always don't share a MWE. Actually, I am working on a LaTeX file which has several themes associated to it and so it is a bit difficult to put up a MWE.  What I wanted to inquire is that how to Slightly Tab a complete paragraph horizontally. I am using \quad and it just tab the first line but not the rest of the lines of the paragraph.


Redirecting *.aux, *.log files, with a command in the tex file

Is there a latex command that can be included in a file compiled with pdflatex that can direct the *.aux, *.log files resulting from the compilation process, to a specific folder ?  I have seen several posts on this question in stack-exchange however all of them have solutions which involve making changes in the latex front-end used. I repeat, I am looking for a command that we can just include in the tex file.  The reason for doing this is that I wish to collaboratively edit tex files with another person over dropbox. We may be using different editors or operating systems even. So, I want the change to be made on the tex file that accomplishes the task of redirecting of *.aux, *.log files to a specific folder.


Show that $f$ is not differentiable at $(0,0)$ - $\frac{x_1^2x_2}{x_1^2+x_2^2}$

Let the function $f: \mathbb{R^2} \to \mathbb{R}$ defined as       $$f(x) =    \begin{cases}    \frac{x_1^2x_2}{x_1^2+x_2^2},       & \quad \text{if } (x_1,x_2) \not= 0  \\  0,  & \quad \text{if } (x_1,x_2) = 0  \\    \end{cases} $$      Show that $f$ is not differentiable at $(0,0)$.   I think I can use the directionnal derivative or the polar coordinate, but I don't know how.  Is anyone is able to explain to me how I can use these properties? If I can't, could you propose to me an alternative?  P.S. Please, don't try to use a very specific analysis theory; I am only an undergraduate student (bachelor).


I have here a very long table list and the client is telling me that all the data are important and they wanted to see it. Is there any way to make this a user friendly?


I installed  (Precise Pangolin), 64 bit. Nowhere was I asked to set password for root.  I just installed  software. It was installed under the /root folder by default. Now I try do something on that folder. I tried with su to switch to root, but I don't know its password.   Should I always use sudo or get the default root password, if any?  How do I create a  for software installed inside the /root directory?


Are reputation points counted in total or per site?

I'm kinda confused, because I'm new enough that I can't upvote but I know that I've had at least 15 notifications about reputation points... Where do I find my reputation count anyway?  And as a side question, how long have the users with 200 reputation points been here? There's a bunch of things that don't work unless you have that much, including the flair badges and that little graph on your user profile.   Edit: I realize there is a similar-sounding question, but that question/answer thread never explained that a user has a different reputation score for each stack, unlike the answers found here. (Thanks)


So all my friends keep telling me that if you add up all the numbers from 1 to infinity, (1+2+3+4...) then the answer is -1/12. They showed me this proof with infinite sums, but I didn't understand it, so all I'm asking is does it really equal -1/12?


It seems to me that there is no such thing as time. There  is only movement in the universe and we compare our own movement to a different object to have a sense of time. It can be a clock or a atomic vibration.  Does this view of time work within the current framework of phsics?  Do physicists have an explanation/proof about time's existence?


"There were undefined references. Please (re)run Biber" when reference is in a table despite all references are considered

My output looks fine. However there are the following warnings when compiling a document with references inside a table, when using TexLive. With MikTex this warnings will not occure:  There were undefined references. Please (re)run Biber on the file: minimalexample and rerun LaTeX afterwards.  Here is a minimal example: \documentclass[preview]{standalone} \usepackage{luatex85,tabularx} \usepackage[style=numeric-comp,backend=biber,sorting=none,maxbibnames=99]{biblatex} \addbibresource{references.bib}  \begin{document}     \begin{table}         \centering         \begin{tabularx}{\linewidth}{c}             \cite{reference} \\         \end{tabularx}     \end{table}     \printbibliography \end{document}  The appropriate bib-file is: @article{reference,   title={Reference Title},   author={Name, S.},   journal={Journal},   volume={1},   number={1},   pages={1},   year={2011},   publisher={Publisher} }  Is there a mistake in my code or could it be a bug? Edit: The Biber log file is:  [0] Config.pm:304> INFO - This is Biber 2.12 [0] Config.pm:307> INFO - Logfile is 'minimalexample.blg' [24] biber:315> INFO - === Fr Feb  5, 2021, 23:31:16 [46] Biber.pm:371> INFO - Reading 'minimalexample.bcf' [106] Biber.pm:889> INFO - Found 1 citekeys in bib section 0 [119] Biber.pm:4093> INFO - Processing section 0 [131] Biber.pm:4254> INFO - Looking for bibtex format file 'biblatex-examples.bib' for section 0 [139] bibtex.pm:1512> INFO - LaTeX decoding ... [362] bibtex.pm:1329> INFO - Found BibTeX data source 'biblatex-examples.bib' [386] UCollate.pm:68> INFO - Overriding locale 'en-US' defaults 'normalization = NFD' with 'normalization = prenormalized' [387] UCollate.pm:68> INFO - Overriding locale 'en-US' defaults 'variable = shifted' with 'variable = non-ignorable' [387] Biber.pm:3921> INFO - Sorting list 'none/global//global/global' of type 'entry' with template 'none' and locale 'en-US' [387] Biber.pm:3927> INFO - No sort tailoring available for locale 'en-US' [389] bbl.pm:636> INFO - Writing 'minimalexample.bbl' with encoding 'UTF-8' [390] bbl.pm:739> INFO - Output to minimalexample.bbl


Prove that $\sqrt{\frac{a}{b+c}}+\sqrt{\frac{b}{a+c}}+\sqrt{\frac{c}{a+b}} \gt 2$

Prove that If $a,b,c \in R^+$ Then  $$\sqrt{\frac{a}{b+c}}+\sqrt{\frac{b}{a+c}}+\sqrt{\frac{c}{a+b}} \gt 2$$  My try:  I assumed:  $$x=\sqrt{\frac{a}{b+c}}$$  $$y=\sqrt{\frac{b}{a+c}}$$  $$x=\sqrt{\frac{c}{b+a}}$$  Then we have:  $$\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=\left(\frac{a}{b}+\frac{b}{a}\right)+\left(\frac{a}{c}+\frac{c}{a}\right)+\left(\frac{c}{b}+\frac{b}{c}\right)$$  Now by AM GM Inequality we have:  $$\left(\frac{a}{b}+\frac{b}{a}\right) \ge 2$$  So we get:  $$\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2} \ge 6 \tag{1}$$  Using $(1)$ we need to prove:  $$x+y+z \gt 2$$  Any idea here?


Getting rid of type 3 fonts for manuscript

I am trying to submit a pdf file made with pdflatex on linux to a journal. I did not realize the issues with type 3 fonts. Using pdffonts, the issue seems to be coming from .eps image files that I have from using \includegraphics.   Unfortunately, I made the graphics using python and matplotlib and from doing research it seems like by default it will make texts using type 3 fonts. Worst of all, all the data to make these graphs are on my school computer and I am on break for a month. I have spent the last couple of hours trying to research anyway to get around remaking these figures. Is there anyway I can convert a .eps file to not have type 3 fonts once it is created? I've tried searching for solutions during the compiling process with pdflatex or using inkscape or something to convert it, all to no avail.  I'm really hoping somebody has a solution so I don't have to wait a month to get this paper submitted.


ubuntu 17.10 popup keyboard on touch screen

I have installed 17.10 on a Lenovo 14 flex with touch screen.  Each time I touch the screen a keyboard pops up.  I can find no way to disable this feature.  I can not type using it, making this even more annoying.  Any way to disable this?  Thanks


undefined reference to Stack::push(int const&)

Stack is a template class with a vector m_elem. Vector type is also template. So in main I am trying to push an int into the vector but it is showing undefined reference. No idea y is this happening. The program is as follows.  main file  int main() {        Stack<int> intStack;     intStack.push(7);     return EXIT_SUCCESS; }   .h file  template<class T> class Stack {     public:         void push(T const& elem);     protected:     private:         vector<T> m_elem; };   .cpp file  template<class T> void Stack<T>::push(T const& elem) {     m_elem.push_back(elem); }   Error showing is  undefined reference to Stack<int>::push(int const&)   Can someone please help me. Thanking You in advance.