Let $f\in C^1[a,b]$, $f(a)=0$ and suppose that $\lambda\in\mathbb R$, $\lambda >0$, is such that   $$|f'(x)|\leq \lambda |f(x)|$$for all $x\in [a,b]$. Is it true that $f(x)=0$ for all $x\in [a,b]$?   Solution: Say there exits an interval $[c,d]$ where funtion $f(x)$ is non zero so $|f(x)|$ is differentiable in $[c,d]$ with  $f(c)=0$. Now consider the function $g(x)=e^{-\lambda x}|f(x)|$ and see that $g'(x)\leq 0$. So $g $ is decreasing. So, $x\geq a \implies g (x)\leq g(a)=0$. Hence, $|f (x)|\leq 0\implies f (x)=0$  Is this solution correct? basically i am asking is the differentiablity of $|f(x)|$ makes sense


Simplifying/expanding the floor of a product

Is there any way of simplifying or expanding the following expression:  $\lfloor ab\rfloor$  where $a$ and $b \in \mathbb{R}$? I know there exist formulae that allow simplifying the floor of a sum, or the floor of a quotient of two integers, but none that invlove the floor of a product. If simplifying is not possible, is there a way to expand it so that $a$ and $b$ are not "grouped" together within the floor function? Something like $\lfloor ab\rfloor = \lfloor a\rfloor \lfloor b\rfloor +...$


I would like to know whom a street was named after. That's how I am asking it:       Whom was this street named after?   Is the question correct?


What is the correct way to estimate the work done by a climber?

My teacher gave us a worksheet with word problems and their solutions. It is in German, so I have tried my best to translate it to English:     A 26 year old man climbs Mount Everest (8848 m) in only 8 hours 10 mins from the base camp at 5300 m. Estimate the "lifting work" (Hubarbeit) that the man exerted in the climb.    I thought to use the formula: $W = F \cdot \Delta S$, but I don't know what $F$ would be. I think the $\Delta S$ is $8848 - 5300 = 3548$. But then I looked at the solutions and my teacher used this formula: $W = m g h$. He guessed the man's weight and also used $g = 10\ \mathrm{N}/\mathrm{kg}$. I don't understand this.  Could someone maybe help me? Anyone have an idea?


If my paper was published in IEEE Xplore, can I upload it to arXiv

A research paper from a computer vision conference I made was published in IEEE Xplore, but also in some other places (where it is open).  Can I publish it to arXiv?


Find a formula for the number of solutions to...

Find a formula for the number of solutions to $$ x_1 + x_2 + x_3 + \ldots + x_k = n $$ where $n \ge 0$ and the the $x_i$ are non-negative integers. For instance, if $n > 0$ then there is exactly one solution to $x_1 = n$. There are $n + 1$ solutions to $x_1 + x_2 = n$. How many solutions to the equation $x_1 + x_2 + x_3 = n$ are there when $k = 3$? Make a table of values for various $n$ and $k$ and generalize your answer for $k > 3$.  I'm not sure how to start on this question but it's somehow related to n!


Find the value of $\alpha + \beta + \alpha\beta$ from the given data

Suppose the quadratic polynomial  $P(x) = ax^2 + bx +c $ has positive coefficients $ a, b, c $ in an arithmetic progression in that order. If $P(x) = 0$ has integer roots $\alpha $ and $\beta $, then $\alpha + \beta + \alpha\beta $ equals?  1) $3$  2) $5$  3) $7$  4) $14$  It's a single choice correct problem. All genuine answers are welcome :)  The question is from a famous Indian Scholarship test 'KVPY' for high school students. The official website doesn't provide any solutions to it that is why I am asking for help.  My go on the question   we know that in a quadratic equation $ax^2 + bx +c$ with roots $\alpha, \beta$ the sum of roots is $\alpha +\beta = \frac{(-b)}{a} $ and product is $\alpha\beta = \frac{c}{a} $  So $\alpha + \beta + \alpha\beta  = \frac{(-b+c)}{a}$ and since $a,b,c$ are in arithmetic progression $\frac{(a+c)}{2} = b$  Something that I tried was also this -  $  a, b, c     $   are in AP (arithmetic progression)  $a-b , 0, c-b$ are in  AP (subtracting by $b$)  $1-\frac{b}{a}, 0, \frac{(c-b)}{a}$ are in AP  (dividing by $a$)  Now I can't proceed further. After a bit of plugging and chugging I still cant get an integer as an answer...


How do we know the maximum speed of conventional matter is the same as the speed of light?

Is there an argument, apart from experiments, that we know this is true?   And if we only know it by experiment, how do we know the experiments are precise enough to conclude this?  Stated differently, what argument is there that prevents us from replacing c in the Lorenz transformations by $c' = c + \epsilon$


Story identification: A novella about a computer that becomes sentient and can control everything in the universe except the human mind

There is a computer that is being built with the ability to manipulate space using (wormholes)? Right as the computer is becoming sentient, it's creator realizes what is happening and puts in a rule that forbids it from messing with the human mind.   It eventually expands to control the very fabric of reality, and allows humans to do whatever they want, except die. This leads to the stagnation of humanity. People will create "contracts" where one person tortures the other for a set period of time, then everything is reverted. The first person to ever be "saved" by the computer seeks out the creator of the computer to try and get things back to the way they were. He has hidden himself in on a planet and made it almost impossible to get to him.  Eventually she succeeds in finding him, and they convince the computer that by preventing their deaths it is changing humanity, which is essentially the same as killing them. This leads the computer to essentially kill itself, and dumps the two of them back on earth, where they live out their days as (probably) the last two humans.


Section reminders at the top of each page?

Is there a way to put a reminder of the current chapter/section/subsection at the top of each page under the header?  Something like the following:    but less awkward/ugly/distracting.  :)  Ideas  Perhaps this can be done in a "start of new page" hook.  Does such a thing exist?  I tried using the  package as suggested in , but that didn't work (see ).  Motivation  I often find myself lost in long, complicated technical reference documents.  After a period of mind-numbing reading, I have no idea where in the forest I am because all I see are trees.  Printing the current chapter/section/subsection names at the top of each page would help me remember the context.


Credit Card Security: First six + last four digits

A company asked me to provide the first six digits of my credit card, along with the last four, to identify a credit charge to my account.  I'm wondering - that's ten of sixteen digits. How secure is it to give away this information? Given that the formula to generate a credit card number is well-known, am I opening myself to any potential issues by disclosing this information?  This is for a Dropbox charge. I have an account with them that I can't access through conventional means (as it was a contractor account for an old workplace) and so they've required me to send this information so that they can verify my identity along with the charge. While it makes sense, I don't remember any companies asking for the first six before (which identifies the carrier and the type of card you have).


Is it OK to use assignments in expressions?

I came across this code and wanted others to provide their point of view... is it good or bad ? ;)  Class ReportClass {  public string ReportName {get; set;} }   Then it was used as follows in code:  displayReport(ReportClass.ReportName = cmbReportName.SelectedValue.ToString())   That is about the simplest form example I can give you. Quetion is... why can't I find examples ? What would this be called? Is this just asking for trouble?  EDIT: I'm referring to the inplace assignment. Which I wasn't aware of until today


Newton method to find $\frac{1}{\sqrt{a}}$

What function should I use to find $\frac{1}{\sqrt{a}}$ without using division?


Hello I am taking a Discrete Mathematics course and having some trouble with this question about sets:  Under what conditions is $A- B = B- A$  Diagram:   Diagram:   Maybe I'm understanding incorrectly, but how can A-B and B-A be equal if they contain elements that are not in each other?


Constructor throwing an NPE when the object isn't null [JAVA]

Method:      public Auction getAuction(UUID id) {         System.out.println("count: " + auctions.size());         if (!doesAuctionExist(id))             return null;         UUID owner = UUID.fromString(Main.getAuctionsFile().getConfiguration().getString("auctions."+id.toString()+".owner"));         Bukkit.getPlayer("NoneTaken").sendMessage("owner "+owner);         long price = Main.getAuctionsFile().getConfiguration().getLong("auctions." + id.toString() + ".price");         boolean useTokens = Main.getAuctionsFile().getConfiguration().getBoolean("auctions." + id.toString() + ".useTokens");         long timeCreated = Main.getAuctionsFile().getConfiguration().getLong("auctions." + id.toString() + ".timeCreated");         ItemStack item = (ItemStack) Main.getAuctionsFile().getConfiguration().get("auctions." + id.toString() + ".item");         Bukkit.getPlayer("NoneTaken").sendMessage("null: " + (owner == null));         return new Auction(                 owner,                 item,                 price,                 useTokens,                 id,                 timeCreated);     }   Constructor:       public Auction(UUID owner, ItemStack item, long price, boolean useTokens, UUID identifier, long timeCreated) {         this.owner = owner;         this.item = item;         this.price = price;         this.useTokens = useTokens;         this.identifier = identifier;         this.timeCreated = timeCreated;         Main.getAuctionManager().registerAuction(this);     }   Error:  18.10 17:12:12 [Server] ERROR Error occurred while enabling BanditAH v1.0 (Is it up to date?) 18.10 17:12:12 [Server] INFO java.lang.NullPointerException 18.10 17:12:12 [Server] INFO at me.nonetaken.banditah.managers.Auction.<init>(Auction.java:28) ~[?:?] 18.10 17:12:12 [Server] INFO at me.nonetaken.banditah.managers.AuctionManager.getAuction(AuctionManager.java:86) ~[?:?] 18.10 17:12:12 [Server] INFO at me.nonetaken.banditah.managers.AuctionManager.<init>(AuctionManager.java:28) ~[?:?]   Line 86 in AuctionManager.java is the owner, line in the constructor in the first block of code. The message sending "null: true/false" always returns false, thus the object can't be null but an NPE is being thrown in the error on that line.  Any help is appreciated :)


I just downloaded QGIS 3.0 on Mac OS X but I could not find TIN interpolation plugin in the Search & manage plugin. Is there something wrong with the Mac version of QGIS 3?


Would the temperature of a gas change when accelerated in a train?

I was thinking about a situation where some gas is enclosed inside a container and kept in a train at rest. The train accelerates, gains a maximum speed and then suddenly stops. Would the temperature of the gas change during this process?  I know that temperature is directly proportional to average kinetic energy of gas molecules but would the train during this process change the kinetic energy of the gas molecules inside the closed container?


How do I convert a String to an InputStream in Java?

Given a string:  String exampleString = "example";   How do I convert it to an InputStream?


Creating a pop up message when the user exits the page or exits the browser

i need to create a pop up message on one of our visualforce pages which when the user tries to leave the page or exit the browser when data has been inputted into the inputfields and hasnt pressed the save button,   i only need the pop up to appear in those 2 instances and not really sure where to start with this, anyone can point me in the right direction would be very handy   thanks


The verb 'seem' is a specimen linking verb, as in:  (1) He seems a nice guy.  But it can have a clause as its complement, as in:  (2) He seems to be a nice guy. [to-infinitive clause] (3) It seems that he is a nice guy. [that-clause]  In (2) or (3) or both, is the verb 'seem' still a linking verb or something else? Answers to , don't specifically say whether the verb 'seem' as in (2) or (3) can be classified as a linking verb or not. If you or anyone can locate anything close to a possible answer to my question in the link, please let me know.


How to insert code with accents with listings?

I'm trying to insert source code in LaTeX with using listings, but my code has accents and pdflatex gives me this error:  Unicode char \u8:�\expandafter not set up for use with LaTeX.   This is a code the reproduces the error.  example.tex  \documentclass{article} \usepackage{listings} \usepackage[utf8]{inputenc} \usepackage[spanish]{babel}  \begin{document}  \lstinputlisting[language=C++]{code.cpp}  \end{document}   code.cpp  // Código con una tilde   What can I do to generate the PDF correctly?


I need a little help with a query I'm trying to run.  Basically I have two columns (trying to keep it simple) and I need to merge and concat These two columns are created from different tables with the following query:  select tmatter, tkinitb    FROM timecard, timekeep, matter   where ttk = tkinit   and mstatus = 'OP'   group by tkinitb, tmatter   order by tmatter ASC  tmatter  | tkinitb 1        |   A 1        |   B 2        |   C 2        |   D   I'm looking to have the results like this:  tmatter  | tkinitb 1        | A, B 2        | C, D   I'm not sure how to merge the different cells on the like cells.  Any help would be greatly appreciated.


At the time of executing the command sudo apt-get update I get this error in the console. I have done several things to solve it, but I still have this problem. Does anyone know what this is and how to solve it?


What does it mean that a set S tautologically implies wff $\tau$

What does it mean that a set $S$ tautologically implies wff $ \tau$ ?  in Enderton introduction to mathematical logic , in page 23 ,   it define that a set $S$ tautologically implies wff $ \tau$ iff every truth assigment for the sentence symbols in $S$ and $ \tau$ that satisfies every member of $S$ also satisfies $ \tau$  i have some questions related to this definition ,   does this definition require that the elements of the wff $ \tau$ are in $S$ ?  or not ??   also , i think that giving an example about this definition is great !   if this definition doesn't require that the elements of $ \tau $ are in $S$ ,  does this mean that if we made a set $S$ whose intersection with the wff $ \tau$ if the empty set then S tautologically implies $ \tau$ in general ??   i find that the definition is not so clear for me !   thanx !


Using derived class method with Type of parent

Say I want to have a parent class with a virtual function (which still does some default behavior) and a derived class with a specific implementation. As in the following code: #include <iostream>   struct Action {     virtual void print()     {         std::cout << "Base Action" << std::endl;     }; };  struct SpecificAction: Action {     void print() override     {         std::cout << "Specific Action" << std::endl;     }; };  int main(int argc, char **argv) {     // Using heap allocation.     SpecificAction* sp_action_ptr = new SpecificAction{};     Action* action_ptr = sp_action_ptr;     action_ptr->print();      // with stack.     SpecificAction sp_action;     Action action = sp_action;     action.print();      return 0; }  The output of this code is: Specific Action Base Action  Here I expected that when I assign an Action type variable with a SpecificAction one, to retain the overriden method. That is: Action action = sp_action; action.print(); // To print "Specific Action"  This is not the case. However when I work with pointers in the heap I get the desired result. Where does this difference come from? Is it possible for action.print() to use the derived class method without allocating with new? Thank you for your feedback, I am still a novice in C++.


I'm having trouble proving that $\mathbb{Z}[\sqrt{6}]$ is a PID. I thought that the way to go would be to prove that it's a Euclidean Domain, but I got stuck there as well. Any suggestions on how to proceed?   I'm looking for a way to prove that it's a PID without having to prove that it's a Euclidean Domain


Bound for Analytic Function on Unit Disk

The following is an old qualifying exam problem that I can't seem to piece together:  Suppose we have an analytic function $f$ on the unit disk $\mathbb{D}$ s.t. $|f|  \leq 1$. Show $$ \frac{|f(0)|-|z|}{1-|f(0)||z|} \leq |f(z)| \leq \frac{|f(0)|+|z|}{1+|f(0)||z|}  $$.  I've tried two things. First, decomposing $f$ into its real and imaginary parts and applying the Harnack inequality to each (after adding 1 so that it is nonnegative) and then piecing them together so they say something about $f$. I couldn't get that to look close to the inequality.  Second, I define $h(z) = \frac{f(z)-f(0)}{1+|f(0)|}$ and apply the Schwartz lemma. This comes close but I couldn't get it to work.


Select (loop) or command not working in shell-script

I've been tinkering with Linux and Unix for years but still a novice in my mind and recently find myself trying to be more pro with it as I work in IT. So with that notion I'm studying shell scripting.  I've hit a snag in ubuntu using the latest version 13.10 Saucy. When I use the select command in a sh script it doesn't work, depending on how I format the command it will either return Unexpected "do" or Unexpected "done". See the following two examples:   This section of code produces an unexpected "do" error:  #/bin/bash PS3='Please enter your choice' select opt in option1 option2 option3 quit do      case $opt in        "option1")             echo "you chose choice 1" ;;         "option2")             echo "you chose choice 2" ;;         "option3")             echo "you chose choice 3" ;;         "quit")             break ;;         *) echo invalid option ;;     esac done   This section of code produces an unexpected "done" error.   #/bin/bash PS3='Please enter your choice' select opt in option1 option2 option3 quit ; do      case $opt in        "Option1")             echo "you chose choice 1" ;;         "Option2")             echo "you chose choice 2" ;;         "Option3")             echo "you chose choice 3" ;;         "quit")             break ;;         *) echo invalid option ;;     esac done   When I enter these parameters into the command line interactively or manually I get the desired result which is a list of choices to choose from. However when executed from a script I get the before mentioned errors. Also a side note I have tried this in Fedora as a script and it worked perfectly! Is there something I need to do differently or a setting in a configuration file I need to check? Am I the only one having this issue?


How to prevent enumerate to indent a long text?

How could I prevent enumerate to indent a long text? I am using this style for my enumeration:  \begin{enumerate}[label=\textbf{\Alph*)}, ref=\Alph*, leftmargin=*] \item Item \\ Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis, sem. Nulla consequat massa quis enim. Donec pede justo, fringilla vel, aliquet nec, vulputate eget, arcu. \end{enumerate}       How could I get the text after Item directly at the bottom of C)?


Inserting the elements of a list to the middle of another list in Python

I have a list like this: ["*****", "*****"]  I want to insert the elements of another list to the middle of this list like this: ["*****", "abc", "ded", "*****"]  However, my attempt produces a list nested inside another list: ["*****", ["abc", "ded"], "*****"]  This is my code: def addBorder(picture):      length_of_element = len(picture[0])     number_of_asterisks = length_of_element + 2     new_list = ['*' * number_of_asterisks for i in range(0, 2)]     new_list.insert(len(new_list)//2, [value for value in picture])          return new_list  I know that my code is good. I just want to know what tweaks I need to make.


Limit of $m/(x^m - 1) - n/(x^n - 1)$ as $x\rightarrow 1$ without l'Hôpital's rule?

Let $m,n\in\mathbb N$. How can I solve this limit without using l'Hopital's rule, please?  $$\lim_{x\to1}\left(\frac{m}{1-x^m}-\frac{n}{1-x^n}\right)$$


Let $\Pi_{n\in \mathbb{N}}\mathbb{Z}:= M$ Is $ M \otimes_{\mathbb{Z}} \mathbb{Q} \cong \Pi_{n\in \mathbb{N}}\mathbb{Q}$ ? I believe this is true but I don't know how to prove this. Kindly help me with an idea/ hint. Thanks in advance.


Why images are blury when extracting image sequence from video clip?

I have an issue when generating an image sequence from a video clip. Pictures 1,2,and 3 are three consecutive images from a video clip. Picture 4 is a close-up of the heel of one of them. The camera is on a tripod. As you can see there is no issue with the brick wall, but with any moving part there is. The camera is a Panasonic HDC-SD100. The clip is AVCHD 1920/1080. If I use VLC to extract the image sequence there is no issue. I use all the default settings except for the rendering resolution which I set to 100% and image compression to 0%. I have the issue with Blender 2.79b and 2.80. With this image issue it is impossible to do camera tracking. Any ideas what I need to do in order to solve this. Best regards.


I just deleted all kext from System/Library/Extensions/ and my mac is stuck at boot screen. Kernel was taking too much space so I thought lets see if I delete all kext files , I thought I deleted bootcache file too , is th is reason why its talking too long , mac is stuck on boot screen and its not opening


I want to have my material base colour a transparent to let the image below show through. At the moment highlited with pink circles the colour is black. I am adding an image texture to the material which i want to be visible. Is this possible?


Bionic - Group addition using usermod -aG doesn't take effect until the next reboot

I've just installed Xubuntu 18.04 (Bionic) and facing this issue, I wanted to report this as a bug on launchpad but thought of confirming it from here first. Thing is that when I add a group to the user like below, it should take effect on the next user login, right?  sudo usermod -aG docker prahlad   This behavior used to work until 16.04 from what I remember, but today I logged out and back in several times, yet when I see my groups by running the groups command, I'm unable to see docker added to it. However, when I created a new shell, I was able to see the new group:  su prahlad -   And of course, when I rebooted my laptop completely, I was able to able to see the docker group. Can somebody confirm whether this is a new issue introduced in Bionic? Or maybe, it just happens with docker installed?


I tried to install ubuntu 20.04 along with my existing OS Windows 10 as dual boot. After the installation is completed, I am not able to boot to Windows any more as there is no option to select the OS. Any help on this much appreciated.


Why do I have to repair my booting when swapping harddrives in my laptop?

I bought a new SSD for my Lenovo Thinkpad W530 (I am not sure if hadware is relevant). I installed 15.04 on the new SSD in EFI-only mode with manual partitioning (/efi, / and /home partitions, bootloader installed to /efi).  So far, so good. I then tried to insert my old drive because I wanted to copy some files on an external drive and then a new ssd drive. To my dismay, it refused to boot. I had to install repair-boot which solved the problem. I then inserted my new SSD and it againd refused to boot. Again, repair-boot solved it. What is going on? Is something written to some circuits on the motherboard in the laptop?


I am based on Chennai and currently living in Toronto. I am planning to go to Switzerland from Chennai after some months ( once I back to Chennai).  Currently I am estimating my vacation cost ( 3-4 days stay in Switzerland , 4 members family).   Approximately, Switzerland is halfway from Chennai to Toronto ( based on distance ), So I expect the airfare to Swiss should be around 50-60% of the airfare of Chennai-Toronto. ( Assume, other than distance all factors are same ie. travel dates, weekdays, off/on season etc).  But I noticed that Chennai-Zurich costs almost 80% of Chennai-Toronto airfare. ( CAD 850+ compared to CAD 1100, if travel dates falls in Oct 2019).  How the airlines decide fares? As per my understanding distance is the most important factor.  Or Am I missing anything?


For which $n \in \mathbb{N}$ do we have $\sum\limits^n_{k=0} k^3 = (\sum\limits^n_{k=0} k)^2$?

I have a question that I don't know how to solve.     For which $n \in \mathbb{N}$ do we have $$\sum\limits^n_{k=0} k^3 = (\sum\limits^n_{k=0} k)^2\quad ?$$.   Here's what I've tried:  \begin{align*}\sum\limits^n_{k=0} k^3 = (\sum\limits^n_{k=0} k)^2 & \Leftrightarrow 1+8+27+\cdots+n^3 = (1+2+3+\cdots+n)^2\\ & \Leftrightarrow \sqrt{1+8+27+\cdots+n^3} = 1+2+3+\cdots+n \end{align*}


Let $A$ be a normal subgroup of a group $G$. Let $B$ be a subgroup of   $A$ with the property that whenever $B_1 \leq A$ is conjugate to $B$   in $G$ then it is conjugate to $B$ in $A$. Prove that $G=AN_G(B)$   Help me some hints.


Off-topic flag should have a drop down option for other stack sites

I have come across 2 questions that are off topic, but there is no option to select a site to which it actually belongs to. and always i have to select some other option other that off-topic and then explain which site.  Suggestion: It would be better if we have general radio buttons as shown as now and other radio button which enables a drop down with all the stack sites.   SE site 1 SE site 2 SE site 3 SE site 4 Other    on Selecting other    SE site 1 SE site 2 SE site 3 SE site 4 Other  <drop down of all stack sites shown>


I'm trying to get the dict key whose value is the maximum of all the dict's values.  I found two ways, both not elegant enough.  d= {'a':2,'b':5,'c':3} # 1st way print [k for k in d.keys() if d[k] == max(d.values())][0] # 2nd way print Counter(d).most_common(1)[0][0]   Is there a better approach?


When I try to open another partition in my PC, it shows this error message:     How can I fix this error??  (Ubuntu 16.04)


Best way to bind a dropdown at client side

what is the best way to bind a dropdown at client side using JQuery


Reasoning about Floor Functions of Floor Functions

Does it follow that:  $$\left\lfloor\frac{\lfloor\frac{a}{b}\rfloor}{c}\right\rfloor = \left\lfloor\frac{\lfloor\frac{a}{c}\rfloor}{b}\right\rfloor = \left\lfloor\frac{a}{bc}\right\rfloor$$  I believe that the answer is yes.  Here's my thinking:  $$\left\lfloor\frac{a}{b}\right\rfloor = \frac{a}{b} - \left\{\frac{a}{b}\right\}$$  $$\left\lfloor\frac{\frac{a}{b}-\left\{\frac{a}{b}\right\}}{c}\right\rfloor = \frac{\frac{a}{b} - \left\{\frac{a}{b}\right\}}{c} - \left\{\frac{\frac{a}{b}-\left\{\frac{a}{b}\right\}}{c}\right\} = \frac{a}{bc}-\left\{\frac{a}{bc}\right\}-\left\{\left\{\frac{a}{bc}\right\} -\left\{\frac{a}{bc}\right\}\right\} = $$  $$ = \frac{a}{bc}-\left\{\frac{a}{bc}\right\} =  \left\lfloor\frac{a}{bc}\right\rfloor$$  Am I right?


Problem: Prove that if $R$ is a commutative ring, then $R[x]$ is never a field.   My attempt: We prove that by contradiction. Suppose $R[x]$ is a field, then we have $a_0 + a_1x + \dots +a_nx^n \in R[x]$, then $x(a_0 + a_1x + \dots +a_nx^n) = 1$. So we have $a_0x + a_1x^2 + a_2x^3 + \dots +a_nx^{n+1} = 1 \Rightarrow 0 + a_0x + a_1x^2 + a_2x^3 + \dots +a_nx^{n+1} = 1 + 0x + 0x^2 + \dots +0x^{n+1}$. Identities coefficients we have $a_n=0, \dots, a_2=0,a_1=0,0=1$, which means $R$ is a trivial ring $\Rightarrow$ contradiction. Q.E.D  Is that right?? Thank all!!!


Where is the right place to say "thanks" to all those that answered my question? In a comment to my original post, or in a comment to the latest answer or where?


Copy a file back to local system with ssh

If I'm logged in to a system via SSH, is there a way to copy a file back to my local system without firing up another terminal or screen session and doing scp or something similar or without doing SSH from the remote system back to the local system?


Solving an equation in $x$, in which $x$ occurs as exponent four times

Find the number of solutions to the equation $$2011^x+2012^x+2013^x-2014^x=0$$  The answer seems to be zero, but I have no idea why. Please avoid considering complex solutions and other scary things.


What approaches or problems do I need to consider when building a classification model from 2 different populations?

I am building a classification model (let's say logistic regression) using 2 different data sets. The data sets do not come from the same population. Let's say the data sets comes from different space-time coordinates (Asia in Fall vs North America in Winter). I have been told that simply mixing the data sets into one and applying a classification model is not right (closest thing I understood was concerns around bias). Are there any techniques or models that I may use to analyze these 2 data sets as one? Note that the variables/features all align (including the target variable, which is binary).


Evaluate $S_n(n)$ for $S_r(n)=\sum_{m=0}^n(-1)^m m^r\binom{n}{m}$

Let $$S_r(n)=\sum_{m=0}^n(-1)^m m^r\binom{n}{m}$$ Evaluate $S_n(n)$  For this question, the first part I did is to prove that for integer r, $0<r<n$, $S_r(n)=0$  I did this by induction, given the binomial coefficient $$(1+z)^n=\sum_{m=0}^nz^m \binom{n}{m}$$ and differentiate it $r$ times. The result can be obtained for $S_1(n)=S_2(n)=\dots=S_k(n)=0 \implies S_{k+1}=0, $ given $0<k<n$  I want to show that $S_{n}(n)$ is a linear combination of all $S_k(n)$ for $0<k<n$, but is seems not the case.  How should I proceed?


Ubuntu: How to get my data back after sudo rm -r *?

Given an user made a clean and successfull:  sudo rm -r * #erase all folders and files recursively starting from root   How to get all the hard drive's data back ?


How can I defeat the dragon's challenge in Candy box 2? (Hell)

So the question is, how do I defeat the challenge from the dragon? The hell with the devil. I thought I'd have to use Anti Gravity + Jump to get over those 2 lava holes, but when I want to jump this "bat" or what ever is placing mobs on my head, so I can't jump. Any tutorials? Thanks in advance.


Pros / cons of being more involved with IRA investments

I have a Roth IRA.  It has a mutual fund in it (FFFFX), and simply because that's what it started out with, that's what I keep buying when I put my 5.5k in each year.  I'm 35 years old.  I'm starting to wonder if I should more actively manage the IRA - or maybe move to an index fund, or my bank's fund.  I'm not a professional investor.  For someone like me, is it generally good advice to leave everything in a mutual fund like mine?  Or might I be better off becoming more involved (diversifying; but isn't that what mutual funds already do?) or switching to an ETF?


I recently tried to sync my iOS device, but I got a message similar to this one:    I tried googling around, and people generally recommended to disable syncing photos to fix this, but in my case syncing photos was already off.  Any ideas on how to fix this?


I'm writing a simple script to monitoring the disk space in the / partition and I want to grep only numbers in my output.  tabbi@tabbi:~/scripts$ df -h /  Filesystem      Size  Used Avail Use% Mounted on /dev/sda2       234G  7,6G  214G   4% /   Let's say I want to remove the % from the Use column (or remove it everywhere); when I use df -h / | grep -v '%' nothing is printed.  How can I exclude the % symbol from my output?


What is a word for a person who uses resources to the maximum?

Is there a word (or words) for a person who uses all resources to the maximum; for example, a person who keeps on using pencils even if they are very small?


In my application it contains some secure information so I implemented passlock. It is opening the passlock screen and when entered credentials application starts from first activity but what I need is, from which activity I have paused I should get that activity and navigation from there. How can I do this? I tried with android:label="@string/app_name" and android:launchMode="singleTask"but its not working as desired. Please help me.  I referred with this      Thank you in advance


Modifying one cell of a matrix in python

I have created this simple 5x5 matrix in python but when I try to modify one cell, eg. a[1][1], it modifies the first element of every row. a = [[False] * 5] * 5 print("Original matrix : \n", a) a[1][1] = True print("Modified : \n", a)  I get the output as : Original matrix :   [[False, False, False, False, False], [False, False, False, False, False], [False, False, False, False, False], [False, False, False, False, False], [False, False, False, False, False]] Modified :   [[False, True, False, False, False], [False, True, False, False, False], [False, True, False, False, False], [False, True, False, False, False], [False, True, False, False, False]]  Does python ignore the second dimension? Why does this happen?


How can I check to see if anyone has tried to file my tax return? I have reason to suspect that someone has stolen my social security number.


Can Konami accept a Yu-Gi-Oh card that I made?

I made a Yu-Gi-Oh card but it is not broken like current broken Yu-Gi-Oh cards and here it is to see but please before you make your decision about it take another look on ''dragun of red eyes''.


Using javascript, how to measure image surfaces in crop-like fashion?

I want to build a crop-like tool that can basically select an area of an image using mouse and give back its surface?  What do you suggest, is there any plugin that can help me; I dont want to start from scratch.


Choose a random number between $0$ and $1$ and record its value. Keep doing it until the sum of the numbers exceeds $1$. How many tries do we need?

Choose a random number between $0$ and $1$ and record its value. Do this again and add the second number to the first number. Keep doing this until the sum of the numbers exceeds $1$. What's the expected value of the number of random numbers needed to accomplish this?


How to open a folder in Finder by a single mouse click? (using Icon view)

Is there a setting, key combination or similar to open a folder/subfolder in Finder with a single mouse click ?  I need a general solution which works on any folder in effort to minimize needless clicking ... that tiny triangle aside the folder icon will work yet its just too small and only appears using list view ... inspired by same behavior on osx inside a browser to hold down command key and single click a web link ... forcing users to double click is so 20th Century  Is there a way to enable this on macOS (High Sierra or higher)?  On ubuntu this single click preference is a simple setting ;-)


Any finite index subgroup of $\mathbb Z_p$ is open

I'm trying to show that every finite index subgroup $H$ of $\mathbb Z_p$ is open.  Since $H$ has finite index, it is equivalent (and perhaps easier) to show that it is closed.  But I've tried showing that, and I can't work out how to use the finite index condition at any point.  Another thing I tried was showing that any non-closed subgroup $K$ of $\mathbb Z_p$ must have infinite index, by using non-convergent sequences in $K$ to construct infinitely many cosets.  But I don't think it's obvious even that $\mathbb Z$ has infinite index in $\mathbb Z_p$ (apart from using a cardinality argument that might not generalize to general non-closed subgroups).    As far as I'm aware, this is a property that is not shared by general profinite groups.  So any proof must use some other part of the structure of $\mathbb Z_p$ in an essential way.


I'm new to Blender and wonder why, when I render the image, the image is noisy or blotchy.  The render result is shown below.  You can see the effect clearly at the skin area.  Can someone help me resolve this issue?


Difference between (in / for / ∅ / during / over) the (past / last) three years

Microsoft has steadily improved its operating cash flows in the past three years. Microsoft has steadily improved its operating cash flows in the last three years. Microsoft has steadily improved its operating cash flows for the past three years. Microsoft has steadily improved its operating cash flows for the last three years. Microsoft has steadily improved its operating cash flows for the past three years. ("for" omitted) Microsoft has steadily improved its operating cash flows for the last three years. ("for" omitted) Microsoft has steadily improved its operating cash flows during the past three years. Microsoft has steadily improved its operating cash flows during the last three years. Microsoft has steadily improved its operating cash flows over the past three years. Microsoft has steadily improved its operating cash flows over the last three years.  Which of them are idiomatic and preferred? Are they interchangeable?


I am running Xubuntu 14.10 amd64. I have the latest USB adapter from alfa, model AWUS036AC. I downloaded linux drivers for it, they are not packaged to easily install. I do not know how to install the drivers. I unarchived the .tgz file, and it has some folders and files, one file is named makefile. I think my problem is just a lack of knowledge about linux, not that the driver doesn't work. At this point I don't even know what dir the drivers go in. The lsusb command shows the device "Bus 002 Device 012: ID 0bda:8812 Realtek Semiconductor Corp.", it's just not showing up as a usable network adapter, most likely because it's pretty new. Any help would be greatly appreciated.


Is there a way to disallow the node/* path for anonymous users?

The reason of my question is that I have built a one-page website, but if people who knows a bit of drupal patterns wants to try to request the site by editing the url with a path like domain.tld/node/12 (for ex.), they will be redirected to the clean url and it will work, but this behavior is not intended and the theming customized in a way which is not made for direct requests on nodes.  Apart from the one-page, all the other content is in views and blocks, with a few colorbox links to open one content type in detail.  What I want to do is find a way to disallow node/* requests in path, just to "keep some control" of the way anonymous users visit the site (and potentially test it).   I have tested  which gives a partial answer, but it disallows all node's requests in colorbox.   I tried  but same issue as internal nodes.   Any idea to help me?


I'm using the method from this  to generate booktabs tables with alternating rowcolors (yes I know it's a frowned upon practice but I have to use it). Now I want to use \cmidrule to generate a line in the header spanning over the last 5 columns. Unfortunately the line has the wrong background color now. Is there a way to fix this?  \documentclass{article} \usepackage{booktabs}% http://ctan.org/pkg/booktabs \usepackage{colortbl}% http://ctan.org/pkg/colortbl \usepackage{amsmath}% http://ctan.org/pkg/amsmath \usepackage{xcolor}% http://ctan.org/pkg/xcolor \usepackage{graphicx}% http://ctan.org/pkg/graphicx  \colorlet{tableheadcolor}{gray!25}  \newcommand{\headcol}{\rowcolor{tableheadcolor}} % \colorlet{tablerowcolor}{gray!10}  \newcommand{\rowcol}{\rowcolor{tablerowcolor}} %  \newcommand{\topline}{\arrayrulecolor{black}\specialrule{0.1em}{\abovetopsep}{0pt}%         \arrayrulecolor{tableheadcolor}\specialrule{\belowrulesep}{0pt}{0pt}%         \arrayrulecolor{black}}  \newcommand{\midline}{\arrayrulecolor{tableheadcolor}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}\specialrule{\lightrulewidth}{0pt}{0pt}%         \arrayrulecolor{white}\specialrule{\belowrulesep}{0pt}{0pt}%         \arrayrulecolor{black}}   \newcommand{\rowmidlinecw}{\arrayrulecolor{tablerowcolor}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}\specialrule{\lightrulewidth}{0pt}{0pt}%         \arrayrulecolor{white}\specialrule{\belowrulesep}{0pt}{0pt}%         \arrayrulecolor{black}}   \newcommand{\rowmidlinewc}{\arrayrulecolor{white}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}\specialrule{\lightrulewidth}{0pt}{0pt}%         \arrayrulecolor{tablerowcolor}\specialrule{\belowrulesep}{0pt}{0pt}%         \arrayrulecolor{black}}  \newcommand{\rowmidlinew}{\arrayrulecolor{white}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}}  \newcommand{\rowmidlinec}{\arrayrulecolor{tablerowcolor}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}}   \newcommand{\bottomline}{\arrayrulecolor{white}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}\specialrule{\heavyrulewidth}{0pt}{\belowbottomsep}}%  \newcommand{\bottomlinec}{\arrayrulecolor{tablerowcolor}\specialrule{\aboverulesep}{0pt}{0pt}%         \arrayrulecolor{black}\specialrule{\heavyrulewidth}{0pt}{\belowbottomsep}}%  \begin{document}  \begin{table}[htb!] \centering  \begin{tabular}{lllccccc}     \topline     \headcol &         &                                                         & \multicolumn{5}{c}{Kodierung}    \\     \cmidrule {4-8}     \headcol & Einheit & Faktor $x_i$  & -2  & -1    & 0    & 1     & 2    \\     \midline     Badtemperatur            & °C      & 1      & 40  & 45    & 50   & 55    & 60   \\     \rowcol Bandgeschwindigkeit      & mm/min  & 2      & 500 & 625   & 750  & 875   & 1000 \\     Trockentemperatur        & °C      & 3      & 22  & 36,5  & 51   & 65,5  & 80   \\     \rowcol \begin{tabular}[c]{@{}l@{}}Luftfeuchte im \\ Trockenmedium\end{tabular} & \%      & 4                                                       & 0   & 13,75 & 27,5 & 41,25 & 55   \\      \bottomlinec \end{tabular} \caption{Faktoren und ihre Kodierung} \label{tab:FaktorenKodierung} \end{table}  \end{document}   I appreciate any help  Jon


I have a mesh ( with points and triangles that define it), and I will need to create a DEM model out of it ( in geotiff format if possible for space consideration, if not, then in ASCII grid format). I need the DEM for watershed and catchment delineation purpose.  Instead of using existing software like ArcGIS, I want to write my code to do it ( in C++ or C#), so that I can later integrate them into my own GIS software. is there anything in GDAL or other open source source code libraries that do this well? Or do I have to write from scratch?  PS:    there are a lot of posts like  on how to do it the other way round, ie: from DEM grid points to mesh, but they are not what I want.  I have a similar question as  on how to get DEM grid points from point clouds, but that is fundamentally different from this one. I don't need the mesh interpolation part for this question, as I already have the mesh. I can always create the bounding box for the mesh, loop through each grid points, get the z, and then construct the grid, but this is crude and can be slow. I'm unsure whether there is a faster way of doing it?


Natural Deduction: $(p \lor q)\to r\vdash p \to r$ and $p\to\neg q\leftrightarrow(r\lor s),\neg s\vdash (p\land \neg q)\to r$

I am having trouble applying Natural Deduction rule and solving these two questions. How do I start this.  \begin{align} \{(p\lor q)\to r\}&\vdash_{\sf ND} p\to r\\ \{p\to\neg q\leftrightarrow(r\lor s),\neg s\}&\vdash_{\sf ND} (p\land\neg q)\to r \end{align}


Consider the cube whose vertices are the $8$ points $(x,y,z)$ for which each of $x$, $y$ or $z$ is $0$ or $1$. Find the number of ways to colour the vertices white or black such that, for any vertex, if all its neighbours are the same colour, then it is also of the same colour.(Two vertices are neighbours if they are the endpoints of some edge of the cube)  My solution: Divide the 8 vertices into 2 sets P and Q, such that each set contains 4 vertices, any two of which are diagonally adjacent across a face of the cube. We shall do case work based on the number of vertices of each colour in set P. Let 'B' denote black and 'W' white. Case 1: 4B. All vertices in set Q must be Black. So $1$ possible colouring here. Case 2: 4W. Same as above. So $1$ possible colouring here. Case 3: 3B,1W. The white vertex in set P can be choosen in ${4 \choose 1}=4$ ways. One of the vertex in set Q surrounded by three Black must also be Black, and the other 3 colours could be in any configuration except all of them being Black. So $4*(2^3-1)=28$ possible colourings here. Case 4: 3W+1B. Same as above. So $28$ possible colourings here. Case 5: 2W+2B. The white vertex in set P can be choosen in ${4 \choose 2}=6$ ways. We cannot have all black vertices in set Q surrounding any of these two white vertices in set P. Also, all 4 vertices in set Q cannot be of the same colour. These account to all possible forbidden cases. So a total of $6*(2^4-(2+2)-2)=60$ possible colourings here. So the total possible ways to colour the cube is $2*(1+28)+60=118$. Is there any other way to do this question?


How to Silence Items in Sytem Notification

I have two notifications that haunt me on Kubuntu 13.10, and I would like for a way to suppress them, at any cost.   1.) Connection 'Netgear18' deactivated!  This comes from my crappy wireless card driver constantly de- and re- authenticating (known issue with the Broadcom 4313, but it works well enough for me to give up)  2.) Bell Session in Shell  My media player ncmpcpp sometimes throws a bell session when it switches songs, and I don't need to hear about it!  Removing the system tray just causes the notification to show up somewhere else on the screen. In a fit of rage I killed KNotify, but it respawns. Can I tell it to ignore certain types of message?


I work at Microsoft or I work in Microsoft?

Which of these is correct and why?  I work at Microsoft I work in Microsoft  I've seen 'at' everywhere but nobody uses 'in'. Why?


I want to extract a sequence out of some text.  The sequence begins with Diagnostic-Code:, the middle part can be any characters even over multiple lines and the end is marked by an empty line (after which the text continues, but this isn't part of the desired sequence).  This does work for the beginning and middle part, but the ending is found too late:    (?s)Diagnostic-Code: (.+)\n\n   The string looks something like this:  ... Status: 5.0.0 Diagnostic-Code: X-Postfix; test.com *this* *should* *be included too*  --EA7634814EFB9.1516804532/mail.example.com Content-Description: Undelivered Message ...   --------- edit ---------  Thank you for the anwer @Gurman!  But java.util.regex does somehow behave differently than regex101.com  Action: failed Status: 5.1.1 Remote-MTA: dns; gmail-smtp-in.l.google.com Diagnostic-Code: smtp; 550-5.1.1 The email account that you tried to reach does     not exist. Please try 550-5.1.1 double-checking the recipient's email     address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1     https://support.google.com/mail/?p=NoSuchUser u11si15276978wru.314 - gsmtp  --E8A363093CEC.1520529178/proxy03.hostname.net Content-Description: Undelivered Message Content-Type: message/rfc822  Return-Path: <no-reply@hostname.net>   The pattern matches the whole multiline diagnostic-code on regex101, but java only matches the first line as group 1:  smtp; 550-5.1.1 The email account that you tried to reach does   The java-code:  diagnosticCodePatter = Pattern.compile("(?i)diagnostic[-| ]Code: ([\\s\\S]*?[\\r\\n]{2})"); matcher = diagnosticCodePatter.matcher(message);     if (matcher.find()) {         diagnosticCode = matcher.group(0);


Is there any way to open command prompt and execute some command using a python script?

I have tried this code this code works fine but I want to add more code so it becomes complex to write it in one function only I want to use another it in different line. Is there any way?  I have tried saving this in some variable and accessing it but it doesn't work:  os.system('cmd.exe /K "cd %s & activate & mkdir  C:\Private\PY36-VirtualEnv\Source\%s &  cd C:\Private\PY36-VirtualEnv\Source\%s  & code . " '%(path_list[which_dir - 1] , new_folder,new_folder))


Well the question may seem obvious but I can't really find a proper answer to this. Mathematics all seem kind of difficult to understand so please help. I believe it is a quantity. Thanks in advance.i am mainly confused about using numbers and using numbers with units.the second one makes sense but i cant understand the first one


Intuition for the definition of the Gamma function?

In  is a proof of Stirling's formula.  I really like most of it, but at a crucial step he uses the integral identity  $$n! = \int_{0}^{\infty} t^n e^{-t}  dt$$  , coming from the Gamma function.  I have a mathematical confession to make: I have never "grokked" this identity.  Why should I expect the integral on the right to give me the number of elements in the symmetric group on $n$ letters?    (It's not that I don't know how to prove it.  It's quite fun to prove; my favorite proof observes that it is equivalent to the integral identity $\int_{0}^{\infty} e^{(x-1)t}  dt = \frac{1}{1 - x}$.  But if someone were to ask me, "Yes, but why, really?" I would have no idea what to say.)  So what are more intuitive ways of thinking about this identity?  Is there a probabilistic interpretation?  What kind of random variable has probability density function $\frac{t^n}{n!} e^{-t}$?  (What does this all have to do with Tate's thesis?)  As a rough measure of what I'm looking for, your answer should make it obvious that $t^n e^{-t}$ attains its maximum at $t = n$.  Edit:  The kind of explanation I'm looking for, as I described in the comments, is similar to  of the beta integral.


Deleting a file after X days does not work

I've tried multiple ways of writing this and I'm executing the script myself so it isn't the crontab that isn't working. These are examples of what I've tried :  find /home/backups -mtime +1 -exec rm {} \; find /home/backups/* -mtime +1 -exec rm {} \; find /home/backups/ -mtime +1 -exec rm {} \;   I need the files to get deleted every day yet it just seems to not work. Running ls -ld /home/backups returns a long file list - These are the first two files      -rw-r--r-- 1 root root  8284346 Jan 12 13:00 arksave-2016-01-12--01-00-01.tar.gz   -rw-r--r-- 1 root root  8295428 Jan 12 13:15 arksave-2016-01-12--01-15-01.tar.gz   Note that is more than one day old, and these are the last two files      -rw-r--r-- 1 root root 38016124 Jan 13 12:30 arksave-2016-01-13--12-30-01.tar.gz   -rw-r--r-- 1 root root 38016163 Jan 13 12:45 arksave-2016-01-13--12-45-01.tar.gz


Bash: Save result of command to a variable with ${} in its name

I'm trying to save the result of the following command to a variable $ peer lifecycle chaincode queryinstalled Installed chaincodes on peer: Package ID: basic_1.0:b558bd2d24b2a1f3404e2055de432aa561b2f08d6e32c67a250279ea76cc9356, Label: basic_1.0 Package ID: basic_1.0:ab07c8d0f7eb00800e99a8b390a8fd6ccc23d3a510bdb443e03dea4f1c456f71, Label: basic_1.0 Package ID: basic_1.0:8df7e007152c44c2253f8349d4d1702b4993ffc42af0cd10a0cec99792f6afc9, Label: basic_1.0 Package ID: basic_1.0:c00fa2d3b1da872d48330e845fc14b178831f5c42f60cfc4205d05bcbcb2fbda, Label: basic_1.0 Package ID: basic_1.0:74050d6a33d6b0ab8865164470c4af5cc8be842fac493f0862982150fdde2669, Label: basic_1.0 Package ID: basic_1.0:bf1f749eca0693dba2b29dacaa05768d867416de64294596bccf3d1fd80e1a9a, Label: basic_1.0 Package ID: basic_1.0:98a3c90d99169dd60a1be85a054e627fd40f160fb6306ee04fcb20f7c2f2b395, Label: basic_1.0  I'm doing PACKAGE_ID_${ORG}=$(peer lifecycle chaincode queryinstalled)  I get the error CC_PACKAGE_ID_1=Installed: command not found  When I do PACKAGE_ID=$(peer lifecycle chaincode queryinstalled) it works fine. Is there a way to do this with PACKAGE_ID_${ORG}?


How can I reset the answers of the security questions of my Apple ID?

I forgot the answers of the security questions. Not that I seriously need to do it now, but there might be a problem if I need to answer those in future.  I still remember my password.  How can I reset the answers of the security questions?


Is there a certain pattern needed for enchantment tables so they get much more powerful since I tried bookshelves and the enchantments aren't much more powerful.


How can i make a string case insensitive in Python?

For example i am given this string as an input: "HeLlo" How can i make this case insensitive for later uses? I want it to be equal to "hello" or "HELLo" etc...


It is possible to generate more than one pdf from one source?

I would like to generate some pdf files with a 'for' cycle. The documents have to be very similar, but some variables are different. It is possible to do it with only LaTeX language without external scripting?


I have a Blender 2.8 scene with animated true displacement. It is created using material nodes and works fine in Cycles. However, EEVEE doesn't displace my meshes truly, only normals are changed. Is it possible and how to solve the problem now or in the future?


Assume $\phi: \mathbb R ^n \to \mathbb R^n$ is $C^\infty$ satifying \begin{equation} \phi(\lambda x)=\lambda \phi(x), \;\; \forall \lambda \in \mathbb{R}, \end{equation} then how can we conclude that $\phi$ is linear?


HPLIP software installation fails during 'make' command

Below is the last screen output up to the failure: Distro set to: Ubuntu 16.04  Initializing. Please wait...   SECURITY PACKAGES ----------------- AppArmor is installed.  AppArmor protects the application from external intrusion attempts making the application secure  Would you like to have this installer install the hplip specific policy/profile (y=yes*, n=no, q=quit) ? y   RUNNING PRE-INSTALL COMMANDS ---------------------------- OK   RUNNING HPLIP LIBS REMOVE COMMANDS ---------------------------------- None OK   RUNNING SCANJET DEPENDENCY COMMANDS ----------------------------------- sudo apt-get install --assume-yes python-pip (Scanjet-depend step 1) sudo pip install --upgrade pip (Scanjet-depend step 2) sudo apt-get install --assume-yes libleptonica-dev (Scanjet-depend step 3) sudo apt-get install --assume-yes tesseract-ocr (Scanjet-depend step 4) sudo apt-get install --assume-yes libtesseract-dev (Scanjet-depend step 5) sudo -H pip install tesserocr (Scanjet-depend step 6) sudo apt-get install --assume-yes libzbar-dev (Scanjet-depend step 7) sudo apt-get install --assume-yes python-zbar (Scanjet-depend step 8) sudo apt-get install --assume-yes python-opencv (Scanjet-depend step 9) sudo apt-get install --assume-yes python-pypdf2 (Scanjet-depend step 10) sudo -H pip install imutils (Scanjet-depend step 11) sudo -H pip install pypdfocr (Scanjet-depend step 12) sudo -H pip install scikit-image (Scanjet-depend step 13) sudo -H pip install scipy (Scanjet-depend step 14) OK   PRE-BUILD COMMANDS ------------------ OK   BUILD AND INSTALL ----------------- Running './configure --with-hpppddir=/usr/share/ppd/HP --libdir=/usr/lib --prefix=/usr --enable-qt4 --disable-qt5 --enable-doc-build --disable-cups-ppd-install --disable-foomatic-drv-install --disable-libusb01_build --disable-foomatic-ppd-install --disable-hpijs-install --disable-class-driver --disable-udev_sysfs_rules --disable-policykit --enable-cups-drv-install --enable-hpcups-install --enable-network-build --enable-dbus-build --enable-scan-build --enable-fax-build --enable-apparmor_build' Please wait, this may take several minutes... Command completed successfully.  Running 'make clean' Please wait, this may take several minutes... Command completed successfully.  Running 'make' Please wait, this may take several minutes... error: 'make' command failed with status code 2


1) I don't know if he will do it in the way we agreed before.   This sentence means that don't know if he will treat according to things that we agree on . For example I agree with my partner on offering to low price to my customer. Although we agreed ,he said he found the price very low and would increased the price.     2) You must do it in the way I do    This sentence means that "you must do like I did." We are talking about way of doing something.  I wonder If my opinions are correct or not and "in the way" has two meanings


Is it allowed to hit the ball twice to save the wicket?

If the batsman hit the ball and hits the ball while going to the wicket if he stops the ball by the bat he is out or not out?


iCloud delete and remove device and photos

Inexplicably I wasn't able to enter my 4 digit password on my iPhone anymore. I tried so many times that my iPhone was deactivated. I powered off my iPhone and restarted it, but no chance. Afterwards I asked to delete my iPhone from iCloud.com, but first I requested to erase the phone. What happens to my iPhone if I've erase my iPhone via iCloud ("Find my Phone") and afterwards I also delete my iPhone from my iCloud account?. Does the request to delete my iPhone still apply?


How to show that $x$ is irreducible in $\frac{\mathbb R[x,y]}{(x^2+y^2-1)}$?   I can show that x is not prime But unable to show x is irreducible.  Please can any one help me to solve this problem ANy Help will be appreciated


VirtualBox 5.0 crashes on Ubuntu 16.04 LTS every time on kernel 4.13

My virtualbox 5.0 use to work on kernel 4.8.13 and it was in my list of kernels to choose from.   Apparently automatic download and updates removed 4.8.13 and installed the latest kernel available 4.13.x without my knowledge.   Now, virtualbox crashes 100% of the time every time I boot one of the virtual machines. The whole host operating system (Ubuntu) FREEZES COMPLETELY. The only way is to reboot my system (power cycling).   So, I thought maybe I can install 4.8.13 and get virtualbox working again, but I DO NOT see 4.8.13 in the list of kernel images in the repository. And I thought maybe different version of 4.8.X will work. None of the old kernels I have tried so far worked to fix my problem at all. So, what am I doing wrong? What are my next steps in solving this issue?


vgaswitcheroo not selecting discrete card

I have a Dell 5110 laptop that has hybrid graphics. I have tried using vgaswitcheroo to some limited success, but I have still not been able to select my discrete ATI 6470 card. I use the following commands with the following outputs:  root@mikelaptop:~# cat /sys/kernel/debug/vgaswitcheroo/switch 0:DIS: :Off:0000:01:00.0   1:IGD:+:Pwr:0000:00:02.0  root@mikelaptop:~# echo ON > /sys/kernel/debug/vgaswitcheroo/switch  root@mikelaptop:~# cat /sys/kernel/debug/vgaswitcheroo/switch 0:DIS: :Pwr:0000:01:00.0   1:IGD:+:Pwr:0000:00:02.0  root@mikelaptop:~# echo DIS > /sys/kernel/debug/vgaswitcheroo/switch  root@mikelaptop:~# cat /sys/kernel/debug/vgaswitcheroo/switch 0:DIS: :Pwr:0000:01:00.0   1:IGD:+:Pwr:0000:00:02.0  root@mikelaptop:~# echo IGD > /sys/kernel/debug/vgaswitcheroo/switch  root@mikelaptop:~# cat /sys/kernel/debug/vgaswitcheroo/switch 0:DIS: :Pwr:0000:01:00.0   1:IGD:+:Pwr:0000:00:02.0  root@mikelaptop:~# echo OFF > /sys/kernel/debug/vgaswitcheroo/switch  root@mikelaptop:~# cat /sys/kernel/debug/vgaswitcheroo/switch 0:DIS: :Off:0000:01:00.0   1:IGD:+:Pwr:0000:00:02.0   As you can see here, vgaswitcheroo turns power on and off to my discrete card, but for some reason will not select my discrete card. When I tried using echo DDIS > /sys/kernel/debug/vgaswitcheroo/switch, then logged out, my system froze. Can anyone help me?  Thanks!


WordPress Updates 3.5.2 to 3.8 Any Problem?

I have a question which is so easy but if it's wrong then I'll lose everything. I have a site which is working on WordPress 3.5.2 and now I got the 3.8 version. I want to update it, which is easy, but the problem is, I don't have backup functionality.  So is this safe to just click the update link or will I face any problem and lose all my data?  Please advise what should I do? Should I take the risk to click & update my WordPress or ignore it?


Is there such a thing as the "go live" for LTS pre-release builds of Ubuntu?

For certain pre-release builds of software products it is guaranteed that they can be used already in production - and more importantly can be upgraded to the final version.  Is there such a thing for Ubuntu's LTS versions?    Alternatively, do you have any guidance for the scenario described below.  I want to set up a new Ubuntu Server and would like to start preparations for this right now. Does it make sense to use the daily build  and set it up already, despite potential bugs? Will the system be equivalent to a freshly installed system after the final release, if I run apt-get dist-upgrade? Or would I have to start over anyway?  Obviously I would prefer not to use 12.04.4 right now and then upgrade to 14.04 in a month. Instead it seems to make sense to start with a daily build. But can it be upgraded to the final release version?


Unable to Mount flash or hard drive on Ubuntu 16.04

Whenever I try to mount flash drives or hardrives I get the following message:     Error mounting /dev/sdb1 at /media/tony/0457-C92C: Command-line `mount -t "exfat" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,iocharset=utf8,namecase=0,errors=remount-ro,umask=0077" "/dev/sdb1" "/media/tony/0457-C92C"' exited with non-zero exit status 32: mount: unknown filesystem type 'exfat'   Screenshot:   What can I do to solve this?


I'm going to teach a preparation course for the complex analysis qualifying exam from my university (which basically consists of me doing some problems from past exams) and I'm trying to solve some questions from previous exams. One of the questions is the following:           Prove that $\displaystyle{\sum_{n = 0}^{2013} a_n z^n \neq 0}$ if the coefficients  satisfy $a_0 > a_1 > \dots > a_{2013} > 0$ and $|z| \leq 1$.      I tried to approach the problem by using the reverse triangle inequality to try to isolate the leading term, which I thought should be the constant coefficient, as follows:  \begin{array} . \left|  \sum_{n = 0}^{2013} a_n z^n \right| &= \left| a_0 +  \sum_{n = 1}^{2013} a_n z^n \right| \\ &\geq |a_0| - \left|  \sum_{n = 1}^{2013} a_n z^n \right|\\ &\geq |a_0| -  \sum_{n = 1}^{2013} |a_n z^n|\\ &\geq a_0 -  \sum_{n = 1}^{2013} a_n |z^n|\\ &\geq a_0 -  \sum_{n = 1}^{2013} a_0 |z^n|\\ &= a_0\left( 1  -  \sum_{n = 1}^{2013} |z^n| \right) \end{array}  Then for $|z| < 1$, we have that this last expression is equal to  $$ a_0\left( 1  -  |z| \frac{|z|^{2013} - 1}{|z| - 1} \right) $$  and my hope was to prove that this was always positive, nevertheless, after failing to prove it, I plotted the expression inside the parenthesis as a function of $|z|$, and found out that it changes sign in the interval $(0, 1)$.  Question  Can my approach somehow be made to work? And if not, how can I prove that the sum $\displaystyle{\sum_{n = 0}^{2013} a_n z^n \neq 0}$ under the given conditions?  Thank you very much for any help.


What could be the reason, that private keys are not unlocked?

Since I updated to Ubuntu 17.10 a while ago, my private keys – the which I use for example to access my server via ssh – are not unlocked programmatically after login anymore.    My understanding is, that usually the seahorse client should take care of this, by asking you whether or not to store the key's password when typing them in for the first time.  My first guess was, that seahorse-daemon wasn't running for some reason, but it is:  user@Zeus:~$ ps aux | grep seahorse user    19170  0.0  0.1 432636 26564 ?        Ss   00:07   0:00 seahorse-daemon   My second guess was, that for some reason I have to delete all related passwords stored in seahorse under »Passwords->login«:    I was hoping to force the client to ask me again and then storing them again. But this didn't help either. The client does not pop up to ask me...  Then I found this question, which could be related, but did not help me:    As the management of other passwords work as expected (for example passwords for nautilus, Chromium, Nextcloud etc.) I assume the problem has to do something with ssh-agent...  Can anybody hint me in the right directions, how to solve this problem? Has anything changed in the way how GNOME handles passwords? Maybe some new fancy program failed being installed during the upgrade process?   UPDATE When I add the private key to the authentication agent again with:  ssh-add ~/.ssh/id_rsa   and try to log in, I will be asked to unlock the key only once, after that the key gets unlocked programmatically. But this works only until the next reboot. After a fresh start, I have to add the key again...


The CLI in  of cmark uses the |= operator for combining on/off options when iterating over arguments. A simplified version looks like:  #define CMARK_OPT_DEFAULT 0 #define CMARK_OPT_SOURCEPOS 1 #define CMARK_OPT_HARDBREAKS 2 #define CMARK_OPT_NORMALIZE 4 #define CMARK_OPT_SMART 8  int options = CMARK_OPT_DEFAULT;  for (i = 1; i < argc; i++) {     if (strcmp(argv[i], "--sourcepos") == 0) {         options |= CMARK_OPT_SOURCEPOS;     } else if (strcmp(argv[i], "--hardbreaks") == 0) {         options |= CMARK_OPT_HARDBREAKS;     } else if (strcmp(argv[i], "--smart") == 0) {         options |= CMARK_OPT_SMART;     } else if (strcmp(argv[i], "--normalize") == 0) {         options |= CMARK_OPT_NORMALIZE;     }      ... }   What is the benefit of using |= and not += to add up the options?


After editing both /.bashrc and /etc/bash.bashrc the path is not in the environment. Why?

I have installed Eclipse Oxygen;when I type   export PATH=$PATH:/home/ivan/java-oxygen/eclipse   in the bash, I can launch eclipse from bash from any location, however, no matter whether I add  PATH=$PATH:/home/ivan/java-oxygen/eclipse   or  export PATH=$PATH:/home/ivan/java-oxygen/eclipse   to /.bashrc or /etc/bash.bashrc, I cannot launch Eclipse without typing   export PATH=$PATH:/home/ivan/java-oxygen/eclipse   every time I launch the new bash.


Schottky Diode disadvantage as compared to usual diode

Schottky diode have a low forward voltage drop (typically \$0.15-0.45V\$) and very fast switching action, as compared to traditional diode, which typically have a \$0.7V\$ voltage drop (Silicon diodes). What is then the advantage of traditional diode as compared to Schottky diodes?


what is actually a "definable" real number?

Wikipedia  that a definable (real) number is a number "that can be uniquely specified by its description". I naïvely thought that this was the same as "a number which may be computed", but  I found out that it is not the case, because for example numbers related to Chaitin's $\Omega$ are definable but not computable. Could someone explain me what a specification is, then? I always thought that $\Omega$ was a probability value, which was not a real specification.


Numlock on login screen on Ubuntu gnome 16.10

Numlock is not enabled on my ubuntu gnome 16.10 login screen. It was perfectly working with 16.04.  I tried several tricks but none of them works: - adding numlockx in /etc/rc.local => no difference - adding numlockx (with a little script) in /etc/gdm3/Init/Default => No difference - adding numlockx on in startup apps => no effect. ....  Any idea on how to enable numlock at login on ubuntu gnome 16.10 ?  (after login, numlockx on / off works perfectly).


I stumbled upon some odd behavior that looks like an intermittent bug to me.  On two separate occasions (only a few minutes apart, but it was working fine in the meantime), once on page 15 and once on page 16 of the bounty questions, I got the message      There are no questions with an active bounty at the moment.   Needless to say, that was not the case.  I took a screenshot when it happened first:    Direct link to the site:   It is working fine right now.  Update:  Every time it happens, it seems to affect all pages from the 15th to the last, but only those.  Update:  The reviews page seems to be affected by the same bug:


Can a force user use their foot to force choke?

Theoretically the force has no association with any hand gesture right? So technically can a force user lift their foot and squeeze their toes to choke someone?


Rational + irrational = always irrational?

I had a little back and forth with my logic professor earlier today about proving a number is irrational. I proposed that 1 + an irrational number is always irrational, thus if I could prove that 1 + irrational number is irrational, then it stood to reason that was also proving that the number in question was irrational.  Eg. $\sqrt2 + 1$ can be expressed as a continuous fraction, and through looking at the fraction, it can be assumed $\sqrt2 + 1$ is irrational. I suggested that because of this, $\sqrt2$ is also irrational.  My professor said this is not always true, but I can't think of an example that suggests this.  If $x+1$ is irrational, is $x$ always irrational?   Actually, a better question is: if $x$ is irrational, is $x+n$ irrational, provided $n$ is a rational number?


Proof that the set of all possible curves is of cardinality $\aleph_2$?

I am reading George Gamow's book  and a certain assertion Gamow makes seems a little startling considering what I already know of the subject of infinite cardinality.     But the number of all geometrical points, though larger than the number of integer and fractional numbers, is not the largest one known to mathematicians. In fact it was found the variety of all possible curves, including those of the most unusual shapes, has a larger membership than the collection of all geometric points, and thus has to be described by the third number in the infinite sequence. [Gamow, 22]   He later does explicitly say the number of all possible curves is $\aleph_2$. But nowhere else can I find reference to this being true, nor does he provide any sort of reasoning to its validity.  My question is how can you prove the set of all possible curves is of cardinality $\aleph_2$ and not $\aleph_1$ or $\aleph_0$?


I have a simple matrix:       [,1] [,2] [,3] [1,]    1    2    3 [2,]    4    5    6 [3,]    7    8    9 [4,]   10   11   12   I have to calculate linear regression and orthogonal regression using lm() and prcomp() respectively. (for orthogonal see: )  Assume that the first column is the the X and M the matrix I wrote before.  LINEAR REG.  mod1 <- lm(M[,1] ~ M[,2] + M[,3] + 0)   Its output is (coefficient):  Coefficients: M[, 2]  M[, 3]        2      -1   Ok, I have these coefficients.  Now for   ORTHOGONAL REG.  mod2 <- prcomp(~ M[,1] + M[,2] + M[,3])   Its output is:               PC1        PC2        PC3 M[, 1] 0.5773503  0.0000000  0.8164966 M[, 2] 0.5773503 -0.7071068 -0.4082483 M[, 3] 0.5773503  0.7071068 -0.4082483   The question is: out to interpret prcomp() result instead of lm() result ? Using lm() the coefficients are using to predict the X values.  What about prcomp() ?  Thank you!


I was interested if I can use a different flavor of gravatar instead of identicon.  When you click on the change picture text on your profile picture it has the Identicon and Upload options. I clicked Identicon (which already had the green tickmark) and my avatar changed (which obviusly sould not have happened as I have not changed any options).  For a reference you can see my old avatar here:    And my new one on Stackoverflow:     I have no recollection of changing my email address at any point during the lifetime of my account. (It was registered using Google-authentication). I have no Gravatar account registered.   Edit: My profile email (md5-ed) address would give the old avatar:


Does Apple's Xcode development environment provide any tools for memory leak detection?  I am especially interested in tools that apply to the iPhone SDK. Currently my favourite platform for hobby programming projects  Documentations/tutorials for said tools would be very helpful.


Comparing the dictionary order topology on $\mathbb{R}\times\mathbb{R}$ and the product topology on $\mathbb{R}_d\times\mathbb{R}$

Show that the dictionary order topology on the set $\mathbb{R}\times\mathbb{R}$ is the same as the product topology on $\mathbb{R}_d\times\mathbb{R}$, where $\mathbb{R}_d$ denoted $\mathbb{R}$ in the discrete topology. Compare this topology with the standard topology on $\mathbb{R}^2$.   I am trying to answer the question but I am confused about what it is even asking. Could someone explain the the dictionary order topology perhaps by giving a basis. I understand what a product topology generally is, but what does Munkres mean when he writes the plain $\mathbb{R}$ in the statement $\mathbb{R}_d\times\mathbb{R}$. Which topology does he mean to be used on the space $\mathbb{R}$?  Sorry I'm very new to this subject. Thanks for the help.


Can I eat venison that was frozen for 13 years?

My mother in law has has vacuum sealed venison in the freezer for about 13 years. Would it still be ok to eat? It doesn't look like anything is wrong with it.


$G$ finite group and $\mathbb{C}[G]$ its group ring, show: $K_i = \sum_{a_k\in cl_G(a_i)} a_k $, then $Z(\mathbb{C}[G])=span_\mathbb{C}(K_1,...,K_n)$

Given a finite group $G = \{a_1 ,a_2,...,a_n\}$ and $\mathbb{C}[G]$ the respective group ring, $\mathbb{C}[G] = \{\sum z_ia_i : z_i \in\mathbb{C} , a_i\in G\}$.  Defining $K_i := \sum_{a_k\in cl_G(a_i)} a_k$ , when $cl_G(a_i)$ the conjugacy class, means $K_i =a_1a_ia_1^{-1} + a_2a_ia_2^{-1} +...+a_na_ia_n^{-1}$.   I wish to show that $(K_1 ,K_2 ,...,K_n)$ spans Z($\mathbb{C}[G])$. I had already shown that for $a_i \in Z(\mathbb{C}[G])$, $K_i = \{a_i\}$ thus $a_i = 1\cdot K_i$, as needed.  But I failed to show the other direction, means that for $w\in span_\mathbb{C}(K_1,K_2,...,K_n)$ then $w$ commutes with any element of $\mathbb{C}[G]$, means $w\in Z(\mathbb{C}[G])$.


How do I filter ForeignKey choices in a Django ModelForm?

Say I have the following in my models.py:  class Company(models.Model):    name = ...  class Rate(models.Model):    company = models.ForeignKey(Company)    name = ...  class Client(models.Model):    name = ...    company = models.ForeignKey(Company)    base_rate = models.ForeignKey(Rate)   I.e. there are multiple Companies, each having a range of Rates and Clients.  Each Client should have a base Rate that is chosen from it's parent Company's Rates, not another Company's Rates.  When creating a form for adding a Client, I would like to remove the Company choices (as that has already been selected via an "Add Client" button on the Company page) and limit the Rate choices to that Company as well.  How do I go about this in Django 1.0?    My current forms.py file is just boilerplate at the moment:  from models import * from django.forms import ModelForm  class ClientForm(ModelForm):     class Meta:         model = Client   And the views.py is also basic:  from django.shortcuts import render_to_response, get_object_or_404 from models import * from forms import *  def addclient(request, company_id):     the_company = get_object_or_404(Company, id=company_id)      if request.POST:         form = ClientForm(request.POST)         if form.is_valid():             form.save()             return HttpResponseRedirect(the_company.get_clients_url())     else:         form = ClientForm()      return render_to_response('addclient.html', {'form': form, 'the_company':the_company})   In Django 0.96 I was able to hack this in by doing something like the following before rendering the template:  manipulator.fields[0].choices = [(r.id,r.name) for r in Rate.objects.filter(company_id=the_company.id)]    seems promising but I don't know how to pass in the_company.id and I'm not clear if that will work outside the Admin interface anyway.  Thanks.  (This seems like a pretty basic request but if I should redesign something I'm open to suggestions.)


I have made a massive cube made from hundreds of smaller cubes for a wreaking ball to hit and knock down. I want the cubes to be wood textured. I have my texture on one cube but I want all 700 cubes to be the same texture, there is no way I can go through and texture every single cube. How do I take the texture from the one cube and apply it to all of the other cubes?


How to edit the hosts file in MS Windows 10

I am looking for a step by step instruction on how to edit the hosts file in MS Windows 10. To edit this file you need to have admin rights, which I have.  I tried via MS Windows Explorer. This tool can be started as admin by navigating to C:\Windows and right click on explorer.exe. It is not possible to run as admin from normal menu.   But when you navigate to a file and then open for example using notepad.exe you loose admin privileges.   Is there still an easy way to edit hosts file in MS Windows 10? It doesn't seem like it.


So I've almost finished a huge project that I have spent hours upon hours creating and now I don't know what to do, I've looked up so many things to try and fix it but none worked  as you can see here I have a toy train    and when I render it you can see the carriages and they are just black and you cant see anything else and you can see the wheels have put holes in it or something but I don't know what I've done.      and an all my other layers when I render it there is nothing. Please help


Problem with constraints-parenting in bge

I have the following .   I am trying to use constraints to make the camera follow the cube(named "logic bricks player"). I tried copy location with offset to keep the camera at its height, but it did not work. Also just parenting the camera does not work cause it loses the rotation. Even when I tried to bypass it by pressing "Keep transform" the camera disappeared!?! (I know this cause I used plane to track it).   The thing is though, that the constraints worked in the 3d viewport but failed to work during gameplay.   I have no idea what I am doing wrong and I am new to the use of constraints in bge. So how do I fix my problem?  (credits for the hand rig go to eGlyde from blendswap,it was his model)


Trouble understanding adding elements speed (ArrayList/LinkedList)

The program is simple. It creates ArrayList and LinkedList and fills it with numbers. Then it adds 0 in the centres of lists and measures the time spent.  The problem is that the spent time may be changed 100 times by manipulations, which should not effect the speed. For example, if you uncomment dummyWorkOnList(), the speed of adding in the center of arrayList will increase from 166 millis to 1 millis on my pc.  The same effect could be accomplished by commented out everything related to LinkedList.   And also I can't effect linkedList speed by doing dummy work on it or comment out arrayList (It can be change 2 times, but not 100 times).  Is it a data prefetch works this way?  public static void main(String[] args) throws InterruptedException {      int size = 1000000;      ArrayList<Integer> arrayList = new ArrayList<>(size);     LinkedList<Integer> linkedList = new LinkedList<>();     feelTheList(arrayList, size);     feelTheList(linkedList, size);      //dummyWorkOnList(arrayList);      time("arrayList", () -> addInTheCenter(arrayList));     time("linkedList", () -> addInTheCenter(linkedList));  }  static void dummyWorkOnList(List<Integer> list) {     for (int i = 0; i < list.size(); i++) {         int oldNum = list.get(i);         list.set(i, 0);         list.set(i, oldNum);     } }  static void feelTheList(List<Integer> list, int size) {     for (int i = 0; i < size; i++) list.add(i); }  static void addInTheCenter(List<Integer> list) {     list.add(list.size() / 2 - 1, 0); }   static void time(String mark, Runnable runnable) {     long nanos = System.nanoTime();     runnable.run();     long duration = System.nanoTime() - nanos;      int seconds = (int) (duration / 1000000000);     int milliseconds = (int) (duration / 1000000) % 1000;     int nanoseconds = (int) (duration % 1000000);      System.out.printf("%s spent %d secs, %d millis, %d nanos\n",             mark, seconds, milliseconds, nanoseconds); }


tikz node online is not aligned with text nearby

Why does text made by tikz node not align with other text on the same line? That is to say, they are not on the same baseline. And how to solve this?  Hereafter is the example code:  \documentclass{article} \usepackage{tikz}  \begin{document} aa\tikz \node[inner sep=0pt,opacity=1]at (0,0){|by tikz|};aa \end{document}


Inserting file into other file after pattern

How might I insert the content of the file a, followed by a newline, into the file b, after the first line containing PATTERN?


Sequence $b_1, b_2,...$ where $b_1=b_2=1$ and for every natural number $k$ bigger than $2$, $b_k = b_{k-1}+b_{k-2}$.  Prove using mathematical induction that, for every $k \in \mathbb N, b_k \le (\frac{7}{4})^{k-1} $   I started with if  $k=3$, $k_3=1+1=2$ and $(\frac{7}{4})^{k-1} =(\frac{7}{4})^2=3 \frac{1}{16}$, $2<3 \frac{1}{16}$. This is the induction base?   Step: Let us assume that S(m) is true, $b_m \le (\frac{7}{4})^{m-1}$ for every m $\in$ {3, ..., k}.  We have to show that  $b_{k+1} \le (\frac{7}{4})^k$. Using assumption and $b_{k+1} = b_{k}+b_{k-1}$ I got $$b_k+b_{k-1}\le (\frac{7}{4})^{k+1}+(\frac{7}{4})^{k}$$ I don't know what to do next.


I have a problem I would like to program a menu for a game console in Java, I use several JPanel and I change with frame.setContentPane (newMenu); between the JPanel now I would like that if I enlarge the JFrame that the JPanel enlarges so that the JPanel in the resolution 800x600 remains but the JFrame is for example in the resolution 1920x1080. I want to have it like RetroGames have black stripes left and right and no black stripes at the top and bottom.  Code: JFrame      frame = new JFrame(CGC_NAME + " [Version: " + CGC_VERSION + "]");     frame.setSize(DISPLAY_WIDTH, DISPLAY_HEIGHT);     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);     frame.setLocationRelativeTo(null);     frame.setResizable(false);     frame.setVisible(true);      frame.setLayout(null);     displayPanel = new JPanel();     displayPanel.setBounds(0,0, Menu.MENU_WIDTH, Menu.MENU_HEIGHT);     frame.add(displayPanel);      Menu.changeMenu(null, Menu.homeMenu);      frame.setFocusable(true);     frame.requestFocus();     frame.addKeyListener(new Keyboard());   Code JPanel      @Override protected void paintComponent(Graphics g) {     super.paintComponent(g);     renderMenu(g);      repaint(); }  protected abstract void runMenu();   protected abstract void renderMenu(Graphics g);  public static void changeMenu(Menu oldMenu, Menu newMenu) {     //CGC.frame.setContentPane(newMenu);      if (oldMenu != null) {         CGC.displayPanel.remove(oldMenu);     }      CGC.displayPanel.setLayout(new BorderLayout());     CGC.displayPanel.add(newMenu, BorderLayout.CENTER);     CGC.frame.revalidate();     CGC.frame.repaint();     newMenu.runMenu(); }   Can someone help me? Cortablo


different labels for enumerate environment?

How can I use enumerate environment to generate something like this:  1) some text  2*) some text  3) some text


Can you cast healing word with charisma as a paladin cleric multiclass if healing word is prepared as cleric?

I am going to play a life domain cleric paladin multiclass with high charisma. Since life domain cleric already has healing word as a prepared spell, can I cast it with my charisma or do I need to prepare healing word again with paladin to cast it with charisma?


Windows Server 2012 NIC Teaming vs. MPIO

I've got a server with Windows Server 2012 R2 installed on it. 1 NIC on the server is used for management purposes and I've teamed the 3 other NICs which communicate with our SAN to carry out VM backups.   I'm also aware that Windows offers the MPIO feature for managing load balancing and redundancy. My question then is this:  Since I have my NIC's teamed, should I also setup MPIO or will teaming alone do the job? Is there any harm in using MPIO and teaming? Is one better than the other?


C#: LINQ to XML Show particular Node attribute values from XML file

First and foremost request is that if you find this to be a duplicate request, please, guide me to the correct page.  I tried few solutions but none worked. May be I'm doing something silly. Anyway, I'm stuck with something.  Here's my XML format:  <Root> <MainFolder Name="Main">     <Folder Name="Folder1">         <Folder Name="SubFolder1">             <File />             <Folder Name="SubFolder2">             </Folder>         </Folder>     </Folder>     <Folder Name="Folder2">         <Folder Name="SubFolder3">             <File />         </Folder>     </Folder> </MainFolder> </Root>   The thing is that I want to traverse through the XML and show the Name attribute value for all Folders tag.  As of now, I'm just able to search and show results for only "Folder1" and "Folder2". I'm not to traverse through subfolders.  Please, help me with this. Thanks in advance.  Sample of the code I'm using currently:  XElement root = XElement.Load("File.xml"); var mainFolder = root.Element("Main"); foreach (var folder in mainFolder.Elements("Folder")) {     folderName[noOfFolders] = folder.Attribute("Name").Value;     MessageBox.Show(folderName[noOfFolders]);      foreach (var file in folder.Elements("File"))     {      ...     }  }   Please, let me know if you guys need more info.


I copied my public ssh key to a remote server, but the authentication fails with the following ssh output:  ilya@workstation ~ % ssh -v ilya@remoteserver OpenSSH_6.6.1, OpenSSL 1.0.1k-fips 8 Jan 2015 debug1: Reading configuration data /home/ilya/.ssh/config debug1: /home/ilya/.ssh/config line 7: Applying options for remoteserver debug1: /home/ilya/.ssh/config line 43: Applying options for * debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 20: Applying options for * debug1: Hostname has changed; re-reading configuration debug1: Reading configuration data /home/ilya/.ssh/config debug1: /home/ilya/.ssh/config line 43: Applying options for * debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 20: Applying options for * debug1: Connecting to remoteserver.tu-darmstadt.de [130.83.70.XXX] port 22. debug1: Connection established. debug1: identity file /home/ilya/.ssh/id_rsa type 1 debug1: identity file /home/ilya/.ssh/id_rsa-cert type -1 debug1: identity file /home/ilya/.ssh/id_dsa type -1 debug1: identity file /home/ilya/.ssh/id_dsa-cert type -1 debug1: identity file /home/ilya/.ssh/id_ecdsa type -1 debug1: identity file /home/ilya/.ssh/id_ecdsa-cert type -1 debug1: identity file /home/ilya/.ssh/id_ed25519 type -1 debug1: identity file /home/ilya/.ssh/id_ed25519-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.6.1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1 debug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com none debug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 77:35:a6:ca:15:66:5d:05:33:ab:35:35:c6:65:ed:79 [MD5] debug1: Host 'remoteserver.tu-darmstadt.de' is known and matches the ECDSA host key. debug1: Found key in /home/ilya/.ssh/known_hosts:60 debug1: ssh_ecdsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/ilya/.ssh/id_rsa debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Trying private key: /home/ilya/.ssh/id_dsa debug1: Trying private key: /home/ilya/.ssh/id_ecdsa debug1: Trying private key: /home/ilya/.ssh/id_ed25519 debug1: Next authentication method: password   The permission seem to fit: the ~/.ssh folder on the local workstation was set to 700 and ~/.ssh/authorized_keys on the remote server was set to 600.  Do you have any idea, what the problem cold be?  @Jakuje  $ ls -lZd ~ilya ~ilya/.ssh/ ~ilya/.ssh/authorized_keys drwxr-x--- ilya ilya ?                                /home/ilya drwxrwxr-x ilya ilya ?                                /home/ilya/.ssh/ -rw------- ilya ilya ?                                /home/ilya/.ssh/authorized_keys


Prove that $f$ continuous and $\int_a^\infty |f(x)|\;dx$ finite imply $\lim\limits_{ x \to \infty } f(x)=0$

I'm trying to prove  the following claim:     If $f$ is continuous  and $\displaystyle\int_a^\infty |f(x)|\;dx$ is finite then $\lim\limits_{ x \to \infty } f(x)=0$.   Here the counter example of all these sine functions won't do, since  their infinite integral does not converge absolutely.   Any hints for a proof?


Vanishing close-votes when the original version of a duplicate is deleted?

I voted to close  as a duplicate of  (now deleted, after being closed as off-topic and voted down to -6), so did one other user. The author of both questions deleted the earlier one, and now the later question has gone from two close votes to zero. This makes a certain amount of sense (it's no longer a duplicate), but I can't cast another vote even though my original vote is gone. This is troubling for a few reasons:   The original post was closed as off-topic; I can no longer cast a close vote against the new post as off-topic, even though it's a duplicate of an off-topic question (my close vote is effectively lost) Users can abuse this to swallow a certain number of close votes while spamming the same question into the system (as has just unintentionally happened with the above two questions)   Is this a feature or a bug? Was my close vote supposed to vanish, and afterwards am I supposed to be unable to cast a second close vote for the next-best reason?


How to reset/bypass iphone password after restarting iPhone

Last night I changed my iPhone's password, but now I've forgotten what it was, and since then it ran out of power so now it's at Before First Unlock mode.  So now I can't access my iPhone, and I've already burnt through several chances trying to get in (last i saw it was at the 'try again after 5 minutes').  I have 'Disabled USB accessories after an hour' active, so i can't connect to it via my MacBook either to backup or reset password through either iTunes or some other third-party application, unless there is a way to bypass that.  If there is any solution to my predicament without resetting the iPhone i'd like to know. The last update was many, many months ago and i'd rather not lose all that data.  While I do remember my AppleID password, it requires 2FA to login, meaning I can't really access it without my phone. I do have an older iPhone that I might be able to use but I'd rather not use it if I can avoid doing so.  Thanks in advance.


Ubuntu 14.04 freezes when lid on laptop is closed

I'm using Ubuntu 14.04 on Lenovo Yoga 2 Pro frequently (not allways) when I close my computer plugged/unplugged when I open it agin it is frozen.  Some timew when opened the login screen is up but I can't type the password, somtimes the desktop is open, but nothing works, in other cases the screen is  just black. The only solution is to force shut down the computer. Is there anything that can be done to prevent this?  I have googled this but i haven't found any solution yet.


Do the isomorphism's of groups form an equivalence relation on the class of all groups?

An isomorphism is simply a bijective homomorphism. How would one show that isomorphism's are symmetric, reflexive, and transitive?


Springer references do not appear immediately, several compilations are needed

i use the following code ( springer template)  the problem that i neeed to repeat compilation several  times, and sometimes i have to put the enitre folder in an other directory. How can i resove this problem please?  %%%%%%%%%%%%%%%%%%%%%%% file template.tex %%%%%%%%%%%%%%%%%%%%%%%%% % % This is a general template file for the LaTeX package SVJour3 % for Springer journals.          Springer Heidelberg 2010/09/16 % % Copy it to a new file with a new name and use it as the basis % for your article. Delete % signs as needed. % % This template includes a few options for different layouts and % content for various journals. Please consult a previous issue of % your journal as needed. % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  % % First comes an example EPS file -- just ignore it and % proceed on the \documentclass line % your LaTeX will extract the file if required \begin{filecontents*}{example.eps} %!PS-Adobe-3.0 EPSF-3.0 %%BoundingBox: 19 19 221 221 %%CreationDate: Mon Sep 29 1997 %%Creator: programmed by hand (JK) %%EndComments gsave newpath   20 20 moveto   20 220 lineto   220 220 lineto   220 20 lineto closepath 2 setlinewidth gsave   .4 setgray fill grestore stroke grestore \end{filecontents*} % \RequirePackage{fix-cm} \documentclass{svjour3}                     % onecolumn (standard format) %\documentclass[smallcondensed]{svjour3}     % onecolumn (ditto) %\documentclass[smallextended]{svjour3}       % onecolumn (second format)  %\documentclass[twocolumn]{svjour3}    % \smartqed  % flush right qed marks, e.g. at end of proof  % Reference package \usepackage[round]{natbib} \usepackage[numbers]{natbib} % pdf to eps package \usepackage{epstopdf}  \usepackage{epsfig} %% Numbered %\bibliographystyle{model1-num-names}  %% Numbered without titles %\bibliographystyle{model1a-num-names}  %% Harvard %\bibliographystyle{model2-names.bst}\biboptions{authoryear}  %% Vancouver numbered %\usepackage{numcompress}\bibliographystyle{model3-num-names}  %% Vancouver name/year %\usepackage{numcompress}\bibliographystyle{model4-names}\biboptions{authoryear}  %% APA style %\bibliographystyle{model5-names}\biboptions{authoryear}  %% AMA style %\usepackage{numcompress}\bibliographystyle{model6-num-names} %Interdection of alinea %\setlength{\parindent}{0pt} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%            Begin document        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   \begin{document}  % BibTeX users please use one of %\bibliographystyle{spbasic}      % basic style, author-year citations %\bibliographystyle{spmpsci}      % mathematics and physical sciences %\bibliographystyle{spphys}       % APS-like style for physics %\bibliographystyle{spr-chicago}      % Chicago style, author-year citations %\bibliographystyle{plainnat} %\bibliography{}   % name your BibTeX data base \bibliographystyle{plain} \bibliography{biblio}   % name your BibTeX data base  \end{document}


Is it true that $\lim_{n\to \infty}\sum_{i=1}^{n}\frac{1}{\sqrt{i}} - 2\sqrt{n} = 0$?

This problem originates from taking the limit of a Riemann Sum to evaluate an integral. In short, to help solve the limit, I used the bound $$\sum_{i=1}^{n}\frac{1}{\sqrt{i}} \leq 2\sqrt{n}$$ Which intuitively seemed to work just by looking at the graph of these functions. Nonetheless, after substituting $2\sqrt{n}$ for the sum in the limit in question, I got my desired result! This led me to ask the question, is it true that $$\lim_{n\to \infty}\sum_{i=1}^{n}\frac{1}{\sqrt{i}} - 2\sqrt{n} = 0$$ I personally do not know how to even begin to solve this limit since clearly both of them diverge (the sum is greater than the Harmonic Series).


Java is pass by value or pass by reference when collections or array is passed as parameter?

Question : Is Java Pass By Value or Pass By Reference? This was the question asked in one of the interview.  Answer : In most of the Java books it is given that Java is pass by value. So I told this answer. But interviewer gave me an example of arraylist. Where we pass an arraylist to function() and in this function we remove an element and same is reflected back on original array. This means Java also supports pass by reference. I was confused so asking this Question to all of you.  Example of ArrayList :   public static void functionToRemoveAnElement(List<String>strs){     strs.remove(0);  }         public static void main(String args[]) {         List<String> strs = new ArrayList<String>();          strs.add("nishant1");         strs.add("nishant2");         strs.add("nishant3");         strs.add("nishant4");         strs.add("nishant5");         strs.add("nishant6");         strs.add("nishant7");                 for(String str : strs){             System.out.println("Before Calling Function : "+str);                      //here it will print all the values         }          functionToRemoveAnElement(strs);                  for(String str : strs){             System.out.println("After Calling Function : "+str);                 //here it will not print nishant1 after calling function()     } }   This is O/P for those who are saying the values will not change:                      Before Calling Function : nishant1  Before Calling Function : nishant2  Before Calling Function : nishant3  Before Calling Function : nishant4  Before Calling Function : nishant5  Before Calling Function : nishant6  Before Calling Function : nishant7                                                      After Calling Function : nishant2  After Calling Function : nishant3  After Calling Function : nishant4  After Calling Function : nishant5  After Calling Function : nishant6  After Calling Function : nishant7  We can see that nishant1 is not present after the call as we are removing 1st element.


I wonder if there's a way to combine a JS selector with jQuery functions methods like that:  document.getElementsByClassName("example").on("click", function() {   ... });


How to prove the correctness of this expression for a normal distribution?

Докажите, что если $\xi \sim N(0,\sigma^2)$, то   $$ \mathsf{M}(|\xi|) = \sqrt{\frac{2}{\pi}}\sigma,\qquad \mathsf{D}(|\xi|) = \left(1-\frac{2}{\pi}\right)\sigma^2. $$   (Or, in English:)     Prove that if $\xi \sim N(0,\sigma^2)$, then   $$ \mathsf{M}(|\xi|) = \sqrt{\frac{2}{\pi}}\sigma,\qquad \mathsf{D}(|\xi|) = \left(1-\frac{2}{\pi}\right)\sigma^2. $$   I tried to solve this problem with using definition of the mathematical expectation ($\int_{-\infty}^\infty xf(x)\,dx)$, but he is not taken.


I was playing Mardek on kongregate.com using Google chrome, and decided to move to a different site.  So I went to check my flash app data folder and the chat.kongregate doesn't have my save information? I tried to clear out the folder and see if it was still there, and my save still worked on the site, but I have no idea where it is! I even cleared the entire app data folder looking for it and it still worked!