Held Packages error while trying to install ROS in Ubuntu 16.04 and 14.04

I'm trying to install ROS Kinetic Kame in my Ubuntu 16.04 VirtualBox VM but when I run sudo apt-get install ros-kinetic-desktop-full, I'm getting the following error :  anant@Ubuntu-ROS-DK:~$ sudo apt-get install ros-kinetic-desktop-full [sudo] password for anant:  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  ros-kinetic-desktop-full : Depends: ros-kinetic-desktop but it is not going to be installed                             Depends: ros-kinetic-perception but it is not going to be installed                             Depends: ros-kinetic-simulators but it is not going to be installed                             Depends: ros-kinetic-urdf-tutorial but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I googled a lot and found many answers on StackOverflow and AskUbuntu but non of them seemed to help.So I tried installing ROS Indigo Igloo in Ubuntu 14.04 but again when I ran the sudo apt-get install ros-indigo-desktop-full command I got the same error but with different packages.Here is the full error message:  anant@Anant-ROS-DK:~$ sudo apt-get install ros-indigo-desktop [sudo] password for anant:  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  ros-indigo-desktop : Depends: ros-indigo-common-tutorials but it is not going to be installed                       Depends: ros-indigo-geometry-tutorials but it is not going to be installed                       Depends: ros-indigo-robot but it is not going to be installed                       Depends: ros-indigo-ros-tutorials but it is not going to be installed                       Depends: ros-indigo-visualization-tutorials but it is not going to be installed                       Depends: ros-indigo-viz but it is not going to be installed E: Unable to correct problems, you have held broken packages.   Thanks.


No conflicts with the variable decleare inside the main and the one decleare inside the namspace

I'm studying c++ namespace and i made a simple code to understand it. In particular i made this code and i don't understand why it doesn't give me the compiler error that i'have already decleare the variable 'a'. Is the compiler help me in some way?  #include<iostream> using namespace std; namespace funzioni_e_altro {     int a=5;     int b=20;     int c=10; } int main() {     using namespace funzioni_e_altro;     int a=0;     cout<<funzioni_e_altro::a<<"\n";     cout<<b<<"\n";     cout<<a<<"\n";  return 0; }   I expect it gave me a compiler error, but it gave me the outputs:  5  20  0


How does virtual particle become real particle in Hawking radiation?

I am new to black hole and general relativity and am just getting introduced to these concepts.  According to my understanding, virtual particle that forms because of quantum fluctuation becomes real particle because of gravitational effects that prolong the life of virtual particle. Is this correct understanding?


How many vertices are in the complete graph with m edges?

I know in a graph with n vertices, there are m = (n(n-1)/2) edges, but in a graph with m edges, how many vertices are there?


how to prevent arm from twisting with rig

Right now I have a base mesh of a human with a basic rig structure, I am trying to have him point a finger gun but whenever I raise the characters arms the mesh twists. (see below)    I don't know what is causing this but I have good topology and the rig vertex groups are all pretty good. any ideas?


How to get dialog box input directed to a variable?

I have been teaching myself bash scripting and have run into an issue. I have written a script to take input from the user, using the 'read' command, and make that input a variable to use later in the script. The script works, but....  I would like to be able to get it setup using 'dialog'. I found out that  'dialog --inputbox' will direct the output to 'stderr' and in order to get that input as a variable you have to direct it to a file and then retrieve it. The code I found to explain this is:  #!/bin/bash dialog --inputbox \  "What is your username?" 0 0 2> /tmp/inputbox.tmp.$$  retval=$?  input=`cat /tmp/inputbox.tmp.$$`  rm -f /tmp/inputbox.tmp.$$  case $retval in 0)  echo "Your username is '$input'";; 1)  echo "Cancel pressed.";;  esac   I see that it is sending the sdterr to the /tmp/inputbox.tmp.$$ with 2>, but the output file looks like 'inputbox.tmp.21661'. When I try and cat the file it gives me an error. So I am still unable to get the user input from the --inputbox as a variable.   Example Script:   echo "  What app would you like to remove? "  read dead_app  sudo apt-get remove --purge $dead_app   So as you can see it is a basic script. Is it even possible to get the variable as a word from dialog --inputbox?


How to roll perception checks for characters who aren't actively looking without arousing suspicion?

This applies to all d20 systems, but with an example from the from the Pathfinder  (emphasis mine):  Stonecunning: Dwarves receive a +2 bonus on Perception checks to potentially notice unusual stonework, such as traps and hidden doors located in stone walls or floors. They receive a check to notice such features whenever they pass within 10 feet of them, whether or not they are actively looking.  In this case, does the GM roll the check in secret or ask the player roll the check? If the GM asks the player to roll for the check, what stops situations like:  GM: (interrupting) "Gimli, Roll a perception check." Dwarf player: "Oh, it's a natural one, I guess I don't see anything." Human player: "Okay, I'll roll a perception check for anything unusual in this room. Nice! 19. How about 19, does 19 work for you?" GM: "Gimli, everything looks kosher to you. Aragon, you notice a rock coloured tarp on the ground here, covering what looks like a pit trap."  In this case, by telling the dwarf to roll his "free" perception check, he's telegraphed to the players that there is something to notice. How can this be fixed, without bluffing checks for nothing in particular to throw off the signal to noise ratio of similar checks?


How to fix "Input/output error" on USB Flash drive?

I am using a 64GB flash drive with Ubuntu, and I still can read and write to it. But when I navigate to a certain folder is gives me the error message  Error when getting information for file '/media/alexander/D0f9-E846/Music/Misc/t....": Input/output error   Instead of the points there are some strange characters to see. I am not able to delete that directory.   The format is "W95 FAT32" and should stay in that format.   I assume formatting the flash drive will help only? Or is there another way of fixing this issue?


What is fast download media and how to remove it?

For the past couple of weeks something was installed on my pc. Either a virus or a bloatware that came alongside another software and I did not notice it. It shows custom system tray notifications (not the default windows 10 ones) about software needing update. If I click Update Now Windows will prompt me if I trust the Fast Download Media software.  Where did this software come from? I am unable to find it in the apps settings to uninstall it. How do I remove it?


How is it that you read a mathematics book? Do you keep a notebook of definitions? What about theorems? Do you do all the exercises? Focus on or ignore the proofs?  I have been reading Munkres, Artin, Halmos, etc. but I get a bit lost usually around the middle. Also, about how fast should you be reading it? Any advice is wanted, I just reached the upper division level.


How do I make GDM the default display manager?

I believe my question says what I am trying to achieve.   Steps I tried to make gdm my default display manager:   sudo dpkg-reconfigure than select gdm as my default. Edit /etc/X11/default-display-manager and change its content to  /usr/sbin/gdm    After the above two steps I logged out myself and after that when I see my login screen it still shows lightdm as my display manager.  What am I doing wrong here.?


Do deathtouch and deathtouch-like effects stop trample damage?

My friend has a trample deck, and I have a  that says "Whenever Stinkweed Imp deals combat damage to a creature, destroy that creature."  Can a creature destroyed this way still deal trample damage?  What if I block with a creature that actually has deathtouch?


Why when I perform RSA 5 times do I get my original input back out?

If I perform RSA on my input 5 times, I get the original input back out. Why is it that often, iterating RSA encryption just a few times cycles yields back the original value, when the public modulus N is small?


Ideas to measure 2D position of an object constrained to X-Y plane

I am working on a project, and an aspect has come up where I would like to measure (track continuously) the X and Y position of an object across a 2D plane. The object is moved by a person, with the object's movement constrained to the 2D plane (so no Z-axis displacement).    Constraints:   I would like measured position resolution of 1 mm, ideally 0.5 mm or better. The space over which the object moves is 30 cm X 30 cm. Whatever method of measurement I use shouldn't significantly constrict the movement of the object. Also, please just assume that the plane on which the object moves is air, and NOT an actual solid surface (for project-specific reasons that are hard to verbalize). The good news is: The object is completely OK to be modified as necessary (LED on top, or string attachments, or anything else).   What might be a method to get that kind of resolution?  I am considering various approaches, but I don't know if any of them will fulfill the resolution requirement. Since there aren't many constraints on my existing system, I am OK with even a complex / bulky implementation, just as long as it's precise enough.  Here are a couple of my ideas so far:  (1) Infrared-based range sensors (only need two actually)   (2) Two long calipers/micrometers connected from the object to the sides   (3) Two strings, each connected from the object to a freely bending strain gage leaf on the side


Does Argon2id provide less protection against side-channel attacks than Argon2i theoretically and/or practically?

LUKS 2 encryption uses Argon2i as the default PBKDF. As the key is used on each access, I guess side-channel attacks are a significant threat factor. However, as I'm not a cryptographer, I am not qualified to say but I'm still interested whether this choice has its grounds. Specifically, I am not interested in whether Argon2i provides less protection against TMTO, but whether Argon2id provides less protection against side-channel attacks. Also, it is interesting whether using Argon2id is practically safe enough for situations in which side-channel attacks are the main threat factor.


send email using webmail domain go to inbox but with php mailer go to spam even if domain already verified

i know there is already others question why mail goes to spam. But all answer i see is they need to authentication their domain first.  If we login to webmail in our domain and sent email directly from there, then it goes to inbox of the receiver. But when we sent the email from third-party application such as php mailer. it will be sent into the spam.  we have authentication our domain using mailchimp but our email still goes to the spam. there is an simple example of phpmailer setting we use.  <?php // Import PHPMailer classes into the global namespace // These must be at the top of your script, not inside a function use PHPMailer\PHPMailer\PHPMailer; use PHPMailer\PHPMailer\Exception;  //Load composer's autoloader require 'src/Exception.php'; require 'src/PHPMailer.php'; require 'src/SMTP.php';  $mail = new PHPMailer(true);                              // Passing `true` enables exceptions try {     //Server settings     $mail->SMTPDebug = 2;     $mail->ismail();     $mail->Host = 'localhost';  // Specify main and backup SMTP servers       //Recipients     $mail->setFrom('info@homecentra.com');     $mail->addAddress('receiver.homecentra@gmail.com');     // Add a recipient      //Content     $mail->isHTML(true);                                  // Set email format to HTML     $mail->Subject = 'Here is the subject';     $mail->Body    = 'This is the HTML message body <b>in bold!</b>';     $mail->AltBody = 'This is the body in plain text for non-HTML mail clients';      $mail->send();     echo 'Message has been sent'; } catch (Exception $e) {     echo 'Message could not be sent.';     echo 'Mailer Error: ' . $mail->ErrorInfo; }   Oh just for information, the email goes to spam only to Gmail user, if it sent to Yahoo or other email provider it wil still sent to inbox. And our email goes to spam only just recently, before we use the same thing even without authentication to mailchimp and it will goes to the inbox. We hope you can give us a solution  here the prove our domain already verified


Been trying to find this book for years...Furturistic, end of civilization, virtual thing

I've googled off and on for years, but I can't seem to find it.  It's set a little bit into the future.  Most humans have been wiped out by a virus, but there are three (or four?) cities left.  Every time a new section of land opens up that can actually be lived on, the cities have a virtual competition (war), to decide who gets it.    I remember that the kids that play the simulations are bred for it (take athletic genes and mix them in), and I remember that one of the kids is deformed, but in the simulation they make him seem normal.  The players aren't supposed to ever meet, but one of the players is a hacker, and set everything up.  I think I read it as a teen - maybe 15 years ago?  I started reading at a college level really early, so it's hard for me to judge.  I don't remember how old it is or anything.  I remember I got it from a library at school, and loved it.  Even though it will probably ruin my memory, I would love to find it again!  Thanks!


Using a variable defined in an If statement?

Sorry if this sounds dumb, but I can't seem to figure out how to use the variable that I defined in the If statements.  import java.util.Scanner;  public class HelloWorld {     public static void main(String[] args) {         Scanner scanner = new Scanner(System.in);            //Prompt for Enchantment Type         System.out.println("Armor/Tool/Weapon");          //Wait for response         String input1 = scanner.nextLine();          if(input1 == "Armor"){             int type = 0;         }         else if(input1 == "Tool"){             int type = 1;         }         else if(input1 == "Weapon"){             int type = 2;         }         else {             int type = 3;         }          //This is where I need to access the type int         if(type == 1){          }     } }   I can't figure out how to use the type string outside of it's block. I know that I'm supposed to read on scope and stuff, but I'd really like someone to just explain it to me.


How to hand solder pads underneath an IC?

I have to design a board with a package case called MSOP-16  It has a large ground pad underneath the IC.  What are good methods for soldering this pad by hand with a soldering iron?    Since it is a prototype, I was thinking to put a large enough via inside of the pad and to heat the via and drop solder through it from the other side after the outer pins have already been soldered.


I sometimes see cases where off is followed by of, and it sounds awkward to me. For example, I would prefer     This story is based on a true story.   to     This story is based off of a true   story.   What do native speakers think/prefer? Should I avoid that kind of usage?


Jquery 'On' method not working on dynamically appended row on table

I have a table with 3 rows added by myself in html. i have a button "Add New Row" which appends a new row with "Edit" button inside last "td". now when i try to click on this newly generated "Edit" button, my script is not getting called. i don't understand what is wrong with my code snippet. I read about jquery "On" method it supposed to be able to generate an event but i don't know why it is not generating event in my code.    $(document).ready(function() {    $(".row").click(function() {       var markup = "
			<button id='myNewRow' class='btn btn-sm btn-mdb-color btn-rounded editbtn' >edit</button>
";       $("table").append(markup);    }); });  $(document).ready(function() {   $('.editbtn').on('click', function() {     console.log('sulabh')      var currentTD = $(this).parents('tr').find('td');     if ($(this).html() == 'Edit') {       $.each(currentTD, function() {         $(this).prop('contenteditable', true)       });     } else {       $.each(currentTD, function() {         $(this).prop('contenteditable', false)       });     }      $(this).html($(this).html() == 'Edit' ? 'Save' : 'Edit')    });  });

       Name       	       Position       	       Office

       Tiger Nixon	       System Architect	       Edinburgh	       <button id="edt" class="btn btn-sm btn-mdb-color btn-rounded editbtn">edit</button>

       Garrett Winters	       Accountant	       Tokyo	       <button id="edt" class="btn btn-sm btn-mdb-color btn-rounded editbtn">edit</button>

       Ashton Cox	       Junior Technical Author	       San Francisco	       <button id="edt" class="btn btn-sm btn-mdb-color btn-rounded editbtn">edit</button>

       Cedric Kelly	       Senior Javascript Developer	       Edinburgh	       <button id="edt" class="btn btn-sm btn-mdb-color btn-rounded editbtn">edit</button>

       Name       	       Position       	       Office


Of a death certificate and a gravestone, which record should be trusted more in determining birth date?

I have an ancestor for whom I have very little information for.  I am trying to identify the exact birth date for this person.  I have a death certificate which lists the birth date as "May 1st", however the gravestone for this person lists "May 4".  I am certain that the numbers were readable, so there is definitely a discrepancy in the dates.  Which record should be trusted more?  I know that the family supplies the date for both the death certificate and the gravestone, however I would suggest the family would be more concerned that it be correct on the gravestone, as the death certificate might be created in haste.  Is there general guidance for this?  For those who may be curious, attached below are the records.  I missed it before, but the year of the birthdate is actually different by 1 as well. (1962 on the gravestone and 1961 on the death certificate)  I am actually more concerned about the year than the actual date, of course.


Are these studies about red algae reducing cold virus by 92% believable?

I was using this spray meant to hasten recovery from the common cold. A study [1], sponsored by the pharmaceutical company that produces the spray, stated it reduced virus by 92% (this value only appear on the promotional material), and so shortens the duration of the common cold.  Meanwhile a doctor told me that these kinds of things don't work.  I found some "similar" studies [2,3, 4, 5 ,6] but I lack the competence to assert their value.  Does someone have some perspective on this? Are these believable studies? Was it well designed, and has it been duplicated?  If so, why wouldn't the pharmaceutical produced a certified and expensive drug instead of a no-prescription drug? I would think anything that would hasten common cold would get an enormous buzz (and profit...).  [1]  [2]  [3]  [4]  [5]  [6]


How to correct "Malformed line in sources.list"

I know the question how to correct a malformed line in sources.list has been asked.  I tried to follow the instructions on the posted answer but I can't access sources.list when I enter sudo -H gedit /etc/apt/sources.list I get the following:  o protocol specified Unable to init server: Could not connect: Connection refused  (gedit:18598): Gtk-WARNING **: cannot open display: :0 bill@bill-GA-880GA-UD3H:~$


How can I encrypt or obfuscate Flask code?

For safety reasons, is there any way to protect flask app code?  I have tried to compile a .py into a .pyc, but the web app won't run.  I have also tried to use a , but the effect is not ideal.  Whether the flask application can be packaged by pyinstaller or cptyhon.


Sufficiently many idempotents and commutativity

It is a well-known result that if a ring $R$ satisfies $a^2=a$ for each $a\in R$, then $R$ must be commutative. See  for proof.  I am wondering whether the same result holds for finite rings if we only assume sufficiently many (but not necessarily all) elements of the ring are idempotents. Recall that an element $a\in R$ is called idempotent if $a^2=a$. For example, suppose $R$ is a finite ring in which at least $80$% elements are idempotents. Can we conclude that $R$ is commutative? More generally,      Does there exist an absolute constant $0<k<1$, such that whenever a finite ring $R$ satisfies   $$\frac{\textrm{Number of idempotents}}{|R|}\ge k$$ then $R$ is   commutative.   Motivation: We know that if every element of a group $G$ satisfies $a^2=1$, then $G$ must be abelian. This is a relatively easy exercise. However, it turns out that we only need 75% percent of elements to satisfy $a^2=1$ in order force $G$ to be abelian. See  For reference, $a\in G$ is called involution  if $a^2=1$.


Intel Ethernet Connection I219-V not working under Linux on an ASUSPRO B laptop, e1000e driver reports: "The NVM Checksum Is Not Valid"

I have a problem with an : when I boot it with Ubuntu 16.04 (or NixOS 16.03) the Ethernet port does not work.  The driver used is , it reports:  $ dmesg | grep e1000e [    5.643760] e1000e: Intel(R) PRO/1000 Network Driver - 3.2.6-k [    5.643761] e1000e: Copyright(c) 1999 - 2015 Intel Corporation. [    5.644308] e1000e 0000:00:1f.6: Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode [    5.877838] e1000e 0000:00:1f.6: The NVM Checksum Is Not Valid [    5.907340] e1000e: probe of 0000:00:1f.6 failed with error -5   Under Windows 7 Ethernet port works fine: I can connect to the Internet. According to Windows, I have .  I have searched for "official" , but none is listed as supporting I219-V.  However, e1000e is listed as supporting I218-V, and I've got a confirmation from  mailing list that e1000e should support I219-V.  Just in case I tried using the latest version 3.3.4 of e1000e, but the error was the same: "The NVM Checksum Is Not Valid."  It looks like indeed there is a mismatch of the checksum of the non-volatile memory of I219-V.  I have tried another ASUS laptop of the same model, and the error was the same, so this does not look like an accidental corruption.  Neither ASUS nor Intel customer support could suggest any solution.  I have discovered , but according to the  (for version 1.6.13.0) it is only intended for PCI, not OEM on-board, Ethernet cards.  However, I decided to run it without parameters just to print the list of Intel network ports, and this is what I've got:  $ sudo ./bootutil64e  Intel(R) Ethernet Flash Firmware Utility BootUtil version 1.6.13.0 Copyright (C) 2003-2016 Intel Corporation  Type BootUtil -? for help  Port Network Address Location Series  WOL Flash Firmware                Version ==== =============== ======== ======= === ============================= =======   1   D017C2201F59     0:31.6 Gigabit N/A FLASH Not Present   I do not quite understand what "FLASH Not Present" means here.  I posed a  on SuperUser.SE about fixing the NVM checksum. Here I am asking if and how anyone managed to successfully install Linux with working Ethernet on an ASUSPRO B8430UA laptop or on any other laptops with Intel Ethernet Controllers which had "The NVM Checksum Is Not Valid" error.


Given a sample of n units out of a population of N, population median can be estimated by the sample median.  How can we get the variance of this estimator?


how to capture output for Process into a C# variable?

I am running below command in windows command prompt and it's giving output like below,  C:\>logman.exe FabricTraces | findstr Root Root Path: C:\ProgramData\Windows Fabric\Fabric\log\Traces\   Now, I am trying to mimic the same in C# program and would like to capture the output (C:\ProgramData\Windows Fabric\Fabric\log\Traces\) into a variable.  How to do this, here's the code I tried,  Process P = Process.Start("logman.exe", "FabricTraces | findstr Root");             P.WaitForExit();             var result = P.ExitCode;


How do I focus in low light for long exposures?

I've been trying to take some long exposure shots at night with my Canon 450D. The problem I'm having is that I can't seem to get a shot in focus. The low light conditions prevent AF from working at all, nor is there enough light for me to get the focus correct by hand. I've tried through the viewfinder and the LCD, but they're both so dark I can't tell if I'm in focus or not.  Perhaps this is a lens issue? I have the 18-55mm ƒ/3.5 kit lens and the 50mm ƒ/1.8 EF lens; neither of them have focus markings, so I'm not sure if I'm hitting ∞ or if my lenses are even capable.  Thank you very much for the suggestions. I’m not able to shine a light, as I’m hoping to get landscapes and night sky shots, and I don’t have anything powerful enough to reflect back. I tried focusing with the 50mm ƒ/1.8 wide open, but I couldn't see anything. I don't think lens speed is going to make a difference.  It sounds like trial and error is my best shot here, which is unfortunate.  Side note: It sucks that the 450D has no way to display the focal length. This info is recorded in the image metadata, so it would seem like it should be available.  I have two more options that I came up with:   Set up during the evening, when there is enough light to focus, then take the shot at night. Potentially impractical due to time, but I see no reason it wouldn’t work. Use another camera. I tried again with my PowerShot S90, and got significantly better results. I was able to manually set the focus to infinity, and the wider angle / smaller sensor meant that I didn't have to worry as much about depth of field causing blur. While the S90 only allows for 15s exposures, CHDK removes that limitation.


How to use Cubic to create a custom Ubuntu live CD image?

How do you install Cubic and use it to create a customized Ubuntu live CD *.iso file that can be burned to CD/DVD or copied to a bootable USB?


If I say something like "SPDT switch" it's assumed to be a non-momentary switch.  Is there standard nomenclature for unambiguously specifying a non-momentary switch?


I have problems with displaying api on my website

I have a coursework related to making a website displaying  this api. and then also using the search bar later on to search for specific things. I have no idea on how apis work. i have created a website with a searchbar and everything. I just dont know how I could display this api. total begginer. if anyone could help me explain js or anything. thank you


Keyboard shortcut to show/hide hidden files in Finder in macOS Mojave

In macOS Sierra, it used to be Command + Shift + .. But that does not appear to work in macOS Mojave. Has something changed?  What is the keyboard shortcut to show/hide hidden files in Finder without restarting in macOS Mojave?


Pagebreak doesn't work with floats and longtabu

I'm using LuaTex. If i have a figure and a longtabu on one page, the text after it just doesn't break.  MWE  \documentclass{scrreprt}  \usepackage{ltablex} \usepackage{tabu} \usepackage{lipsum}  \begin{document}     \begin{figure}         \vspace{10cm}     \end{figure}      \begin{longtabu} {XX}         \textbf{Test} & \textbf{Test} \\      \end{longtabu}      \lipsum[1-5] \end{document}   Result    How to make the text break correct?


Given an integer array of size n, find the k-th largest element without sorting the entire array

I am having some problems with a sorting problem.  The statement:  Write a method KthLargest() that, given an array containing integers in some arbitrary order and an integer k, returns the k-th largest element in the array. Assuming that k is a small number and n is a very large number, your algorithm should be as fast as possible in terms of the worst-case number of comparisons, so do not sort the entire array of size n to find out the k-th largest element. You may use the Arrays.sort() method provided in the Java library.  I have clear ideas on how to do this problem... That is if I can sort the entire array first.  public static int KthLargest(int[] inputArray, int k) {     Arrays.sort(inputArray);     return inputArray[k]; }   However, the problem statement specifically states that I must not sort the entire array.


Can I mix dual-rank and single-rank ram for my Dell XPS 15 9750 laptop

I want to upgrade the ram for my dell xps 15 9750 which is now 8gb ram (2x4gb). I buyed 16gb (ddr4 2666 dual-rank) ram.  Is it possible to mix single-rank (4gb ddr4 2666) and dual-rank (16gb ddr4 2666) together ???  If I mix this together, is there any risk for my laptop ????   Thank you in advances


I'm writing a .sh file which should open monodevelop in root mode. I don't want a terminal to be used for it since it has to stay open.  Now, what I currently got:  #!/bin/bash sudo monodevelop   Now I need to run it in a terminal, but I want my script to bring up a dialog when clicked on Run (not Run in terminal) so I can enter my password for sudo, so it will run monodevelop as root afterwards.  Is there any way I can get this done?


How to use measured step response to tune control system

How does one use a measured step response to tune either a PID or convolution control scheme? Inspired by , I'm interested a more detailed explanation of how to implement a control system based on the measured step response.  I would not try to guess all the effects.  There are probably some non-obvious things going on, and you can't know all the parameters. I would measure the step response.  Find two pump settings that both result in the ball being within the measurable range within the tube.  Then have the controller suddenly switch from one setting to the other open loop.  Meanwhile measure what the ball does over time.  That is the step response.  You can take the derivative of that and get the impulse response.  From the impulse response you can predict the motion of the ball for any history of pump settings, assuming this is a linear system.  It is probably linear enough over the small range of settings to keep the ball within its normal range. You can use this as a simulation base to find the parameters for old fashioned PID control.  Or you can use the impulse response directly to do a convolution control.  You have to low pass filter the control input enough so that convolution kernel doesn't go negative unless your pump is actually reversible and can suck the ball back down.  How exactly does this work? ; I assume "convolution control" is the use of the pole-zero or transfer function, but don't see exactly how to get the parameters. RELATED:  *


Meaning of complex Fourier transformation function

what does it mean, if the Fourier transformation function of an electromagnetic wave is complex? I know that normally the FT function $f(k)$ shows the wavenumbers that are involved in the wave. but i always thought the wavenumbers are always real numbers. Hope someone can help me


Why is my Nikon d3100 with 18/55 lens suddenly fuzzy?

I was taking some inside pictures with my Nikon D3100 and 18/55 lens when, all of a sudden, the lens started to work funny -- the more I zoomed in on the subject, the fuzzier the picture looked in the viewfinder. I shut the camera down. The next day I tried it again and saw the same effect. Then I got the idea of seeing how a picture would actually look on the LD screen, and just as suddenly, what I saw through the viewfinder was normal. Things were OK again. What happened?


Prove that:  $a^3\cos(B-C) + b^3\cos(C-A) + c^3\cos(A-B) = 3abc$  Here a,b,c are the sides of the triangle ABC opposite to angles A, B, C respectively.  My attempt: I tried putting $a = 2R \sin(A)$ and replacing $\sin(B+C) = \sin(A)$ but that didn't help out. I tried applying AM $\ge$ GM but that too did not work out for this question.   Please help me out!!!


Where can I buy a "roaming" or "international" SIM card — one with attached phone numbers in multiple countries?

In the past I have found two companies that offered one sim card with multiple (international) numbers attached to it. The first one, of which I forgot the name, offered one sim card with the possibility to add different european numbers to it. They don't longer exist, hopefully because they were ahead of their time.   I recently learned of the existence of a  that offers a so called "two country sim". It gives both a Surinamese and a Dutch mobile telephone number. You are always available through both numbers. Both in the Netherlands and in Suriname you won't have roaming costs. The company aims at the large Surinamese community in the Netherlands.   I do like this concept. Since I travel frequently I would really like to have such a sim card. Since telesur proves that the technology works, there should be others. Does anyone know of similar companies, preferably combining Belgian, Dutch, German, French and UK numbers?


How can I get Firefox to use Dolphin instead of Nautilus?

I am using dolphin as my file manager and when I download something via firefox, I right click the download dialog and choose "open folder", I always get nautilus.   Why doesn't firefox open the folder with dolphin? Thanks  Note: I tried adding the tag "dolphin" but because of my low rep I can't create new tags :(


Let $f$ be continuous. Then $\int_{0}^{x}\left[\int_{0}^{t}f\left(u\right)du\right]dt=\int_{0}^{x}f\left(u\right)\left(x-u\right)du$

Let $f:\mathbb{R}\to\mathbb{R}$ be a continuous function. Then $$\int_{0}^{x}\left[\int_{0}^{t}f\left(u\right)du\right]dt=\int_{0}^{x}f\left(u\right)\left(x-u\right)du$$ Hint: Prove that if $F'(x)=G'(x)\;\;\;\forall x\in \mathbb R$ and there exists $x_0$ such that $F(x_0)=G(x_0)$, then $F(x)=G(x)\;\;\;\forall x\in \mathbb R$ This is a true/false question BTW. I think I managed to solve it, but I completely ignored the hint which is usually a red flag. therefore I need your opinion. My way: Let $F\left(x\right)=\int_{0}^{x}f\left(u\right)du$ for all $x\in \mathbb R$. LHS: $$\int_{0}^{x}\left[\int_{0}^{t}f\left(u\right)du\right]dt=\int_{0}^{x}F\left(t\right)dt$$ RHS: $$\int_{0}^{x}f\left(u\right)\left(x-u\right)du\underset{\begin{cases} a=x-u & b'=f\left(u\right)\\ a'=-1 & b=F\left(u\right) \end{cases}}{\overset{I.B.P}{=}}F\left(u\right)\left(x-u\right)\biggr|_{0}^{x}+\int_{0}^{x}F\left(u\right)du=$$ $$\left(0-0\right)+\int_{0}^{x}F\left(u\right)du=\int_{0}^{x}F\left(u\right)du$$ Thus RHS=LHS. $\blacksquare$ My biggest concern was integrating by parts while $x$ is both in the integral itself and in the integral bound. thank you.


Facebook verification can't validate my ID

I used my nickname as my middle name and my maiden name, and now I'm locked out of my Facebook account. I did not know that this was not allowed according to the Facebook Terms of Service. When I try to verify my identity with my driver's license, it says it can't validate.   I need to have my Facebook account back only to access my pictures. I have irreplaceable pictures of my family that I want very much not to lose. Any help would be greatly appreciated.


Does exist a singular cardinal $\lambda$ which $\kappa < \lambda \implies 2^{\kappa}<\lambda?$

I'm reading about inacessible cardinals. I don't know anything about them, I just know basic set theory, cardinal operations etc., but I am too curious to leave this question that now I'm (probably) not able to totally understand...  So, a (strongly) inacessible cardinar is a regular uncountable cardinal $\lambda$ such that  $\kappa < \lambda \implies 2^{\kappa}<\lambda$. I know that if the hypothesis of being uncountable is dropped then $\aleph_0$ satisfy the other 2 properties (regular and $\kappa < \aleph_0\implies 2^{\kappa}<\aleph_0)$. But I can't think what happens if we drop the hypothesis of $\lambda$ being regular. Does exist a uncountable singular cardinal $\lambda$ such that $\kappa < \lambda \implies 2^{\kappa}<\lambda$? Why?


I'm new to ubuntu . I have to setup ftp server on ubuntu , vsftpd service always failing after basic installation and changes in /etc/vsftpd.conf file.  I've done below changes after install vsftpd software .  write_enable=YES local_umask=022 chroot_local_user=YES allow_writeable_chroot=YES pasv_min_port=40000 pasv_max_port=40100  I'm getting below error while checking the status of the service. Please help  root@helmor:~# sudo systemctl status vsftpd ● vsftpd.service - vsftpd FTP server    Loaded: loaded (/lib/systemd/system/vsftpd.service; enabled; vendor preset: enabled)    Active: failed (Result: exit-code) since Sun 2017-06-04 19:13:59 IST; 22s ago   Process: 1801 ExecStart=/usr/sbin/vsftpd /etc/vsftpd.conf (code=exited, status=2)   Process: 1798 ExecStartPre=/bin/mkdir -p /var/run/vsftpd/empty (code=exited, status=0/SUCCESS)  Main PID: 1801 (code=exited, status=2) Jun 04 19:13:59 helmor systemd[1]: Starting vsftpd FTP server... Jun 04 19:13:59 helmor systemd[1]: Started vsftpd FTP server. Jun 04 19:13:59 helmor systemd[1]: vsftpd.service: Main process exited, code=exited, status=2/INVALIDARGUMENT Jun 04 19:13:59 helmor systemd[1]: vsftpd.service: Unit entered failed state. Jun 04 19:13:59 helmor systemd[1]: vsftpd.service: Failed with result 'exit-code'.  I'm using this guide


variational problem: obtain the lagrangian from the PDE equations of motion

given the 2 PDE  $$ \Delta u-au_{tt}+u_{t}=0$$  and $$ \Delta u + Du*Df=0 $$  here $ \Delta u $ is the Laplacian $ Du= grau$ and * means scalar product $u_{t} = \frac{\partial u}{\partial t}$  my doubt is what term should i include to get the linear part of the equations $ u_{t} $ and $Du*Df $ from the Euler Lagrange equations in $ R^{n} $ thanks


What is the difference between `cuTexObjectCreate` and `cudaCreateTextureObject `?

The references show little differences between them, only about types used and errors returned.  vs  I have the feeling that the former was introduced first (even though both are for compute capability 3.0) but it was never deprecated (cuda 11.3). Which one should I use ?


Prob. 7, Chap. 3 in Baby Rudin: If $a_n \geq 0$, then how does convergence of $\sum a_n$ imply convergence of $\sum \frac{\sqrt{a_n}}{n}$?

Here's Prob. 7 in the Exercises of Chapter 3 in the book Principles of Mathematical Analysis by Walter Rudin, 3rd edition:      Prove that the convergence of $\sum a_n$ implies the convergence of $$ \sum \frac{\sqrt{a_n}}{n}$$ if $a_n \geq 0$.    How to show this? I have no clue! Can anybody here please be of any help?  Is this result a special case (or application) of a more general result about infinite series?


Performance of using static methods vs instantiating the class containing the methods

I'm working on a project in C#. The previous programmer didn't know object oriented programming, so most of the code is in huge files (we're talking around 4-5000 lines) spread over tens and sometimes hundreds of methods, but only one class. Refactoring such a project is a huge undertaking, and so I've semi-learned to live with it for now.  Whenever a method is used in one of the code files, the class is instantiated and then the method is called on the object instance.  I'm wondering whether there are any noticeable performance penalties in doing it this way? Should I make all the methods static "for now" and, most importantly, will the application benefit from it in any way?


Differences among Doctoral Degrees/titles

I have two colleagues who hold doctoral degrees. They are moving to the US within the next couple months. Both of their doctoral diplomas, one from Europe and the other from South America, literally say: "Doctor of Engineering".   We were discussing about this situation and, although they are doctors, I don't know if it would be "legal" for them to use the PhD letters at the end of their names or if D.Eng would be the adequate choice. So far, they have not been asked to do any kind of nostrification process.  Are there any legal, formal or professional implications associated to this or is it just a matter of putting a set of letter at the end of your name?


Connection pools being reset with Error: 18056, Severity: 20, State: 46. & Perfmon Counters not showing

We are using SQL Authentication (to reduce the number of connection pools) & .NET 4.0 connection strings to connect to SQL Server Enterprise Edition 2012 SP1 on a Windows 2008 R2 Enterprise Server:     Microsoft SQL Server 2012 (SP1) - 11.0.3000.0 (X64)   Oct 19 2012 13:38:57   Copyright (c) Microsoft Corporation   Enterprise Edition (64-bit) on Windows NT 6.1  (Build 7601: Service Pack 1)   We use about 50 servers split into 8 different groups different parts of a website.  Our website is using this SQL Server to log visit tracking data. Over the last few days it has spat out the following messages about the resetting connection pools:     The client was unable to reuse a session with SPID 1327, which had been reset for connection pooling. The failure ID is 46. This error may have been caused by an earlier operation failing. Check the error logs for failed operations immediately before this error message.   Error log reads:     Error: 18056, Severity: 20, State: 46.   The client was unable to reuse a session with SPID 959, which had been reset for connection pooling. The failure ID is 46. This error may have been caused by an earlier  operation failing. Check the error logs for failed operations immediately before this error message.   Login failed for user 'xxxx'. Reason: Failed to open the database 'xxxxxxxx' configured in the login object while revalidating the login on the connection. [CLIENT: 10.xx.xx.xxx]   After some digging, I found this document on the CSS blog:  and this one by Aaron Bertrand: . I know the error number is different but the failure ID is the same with a number of the messages are identical).  Failure ID 46 suggests that the login did not have permissions. Our logins default to the master database and the db name is specificied in the connection string.  I wanted to check the number of connection strings pools, etc. and checked all the counters in Perfmon for .Net Data Provider for SqlServer. It only gave me the option of defaultdomain9675 for the instance, so I selected that assuming that is a system generated ID name for our Datacentre network. Unfortunately all of the counters are reading zero. On one of our other main servers the connection pools are hovering around 10 which is what I expected to see on a healthy server with that kind of load.  My question is 3 fold   Can anyone suggest why the Windows 2008 R2 Server is not showing .Net Data Provider for SqlServer? Has anyone experienced this as I obviously believe that the login not having permissions is a red herring ? If different groups of web servers have the same connection string syntax but with slightly different whitespace, would this cause the server to use another connection pool?   Min & max memory settings are 20GB & 58GB respectively. The server is a dedicated database server with 64GB of RAM. I don't think memory is the issue as the box seems to have a decent page lfe expectancy. Auto close is not enabled. The server is always up: this is a 24x7 website with heavy usage.


"Participate in Meta" should be deleted in Help Center > Privileges

doesn't seem to be necessary because Meta SE doesn't have its own Meta.  According to , the privilege to post a comment is set at 5 reputation. It seems to be far lower than other sites which require 50 reputation points and  is set at 100 reputaiton. Are they intentional?


Using SFINAE to detect a member function

In C++11, to find out whether a class has a member function size, you could define the following test helper:  template <typename T> struct has_size_fn {     typedef char (& yes)[1];     typedef char (& no)[2];      template <typename C> static yes check(decltype(&C::size));     template <typename> static no check(...);      static bool const value = sizeof(check<T>(0)) == sizeof(yes); };   Is there a similar trick for doing this in C++98 without relying on compiler extensions such as typeof?


How to check a part of an input | Python

I want to check a specific part of an input but I don't know "where" it is I tried with this: a = input('Enter command') if a[0:5] == '(Command name)':      if a[7:?] == '(Subject)':          if a[?:len(a)] == '(Choice)':              To be continued  So, the input is divided into three parts; The command, the subject, and which type of the command it will run. But which index should the ? be? I don't know the length of the word. Is it impossible? No, I know that I can make it, just not how.


use one date variable but format it different ways

In a shell script, there are the following variables: datestamp=$(date '+%Y-%m-%d_T%H-%M-%S') datestamp_pretty=$(date '+%m/%d/%Y at %I:%M:%S %p')  The first one is used as part of the output filename while the second one is used to display a nicely readable date and time in the contents of the file.  Since these are created separately, the seconds can be off slightly.  Is there a way to create a single date variable and then format it two different ways?  If so, how is this done?


How can I find a list of job applications I have submitted?

I've submitted several job applications, how can I see a list of all these applications? Does this functionality exists on Stack Overflow Careers? If not present this could be a nice and (I think) simple feature to implement.


Java regex matching a filename(#).extension

Given a List containing filenames, I would like to be able to have the number of potential duplicates of a file. A duplicate is defined as a file whose name is either equal or match the naming convention basename(number).extension .  The first step would be to be able to assert whether a filename matches some pattern. I thought I could do it with a regex. Here it is :      String basename = "file1";     String extension = "txt";     String patternExpression = "^%s(\\(\\d+?\\))??\\.%s$";     Pattern patter = Pattern.compile(String.format(patternExpression, basename, extension));     assert pattern.matcher("file1.txt").find() : "file1.txt should match";     assert pattern.matcher("file1(2).txt").find() : "file1(1).txt should match";   In this code sample, the assertions will pass. The problem with this approach happens when the basename contains some characters interpreted by the Regex compiler. I would like to tell the regex compiler to match exactly the basename and to not interpret it.  1) Is that possible ? 2) Isn't there a way to do that more easily ? I feel like there must be an easy way that I'm completely missing...  Thanks for the help !


I was wondering if it was possible to set the default disk to be used my MSIs, E.G. Install to D:\Program Files by default rather than C:\Program Files, and, if it is possible, how to do so. Thanks!


when gcc/g++ encounters an ICE (internal compiler error), then recent versions of the compiler will print a neat stack trace before exiting.  Questions: What technology is used to implement that? GCC is written in C++, afaik some conservative revision like C++03.  Does it require exceptions, signals or even interpretation of debug-info? Is there host/OS dependence?   Playing around with own C/C++ code, all I found is __builtin_return_address which allows to print code address that can be used to display locations by piping them through an external tool like addr2line...  Note:  Unfortunately, this question has been prematurely closed... In particular, the linked thread does not address the following points:   GCC does not use Boost. GCC does not use external libraries like linunwind or libexcept to all of my knowledge. GCC does not necessarily use glibc. For example I can cross-compile GCC on linux for host mingw32, and stack traces work just fine.


I searched many articles to understand the concept of namespace? But I could not understand. Can anyone explain the concept of namespace with simple example? Why do we import namespace?


I was reading through some of the posts regarding reference to something "possessed" by more than one person, and I can't seem to find an agreement of the usage of of myself.  Is it correct to say the following?     The efforts of myself and my ilk.   I understand that something like:     The efforts of my ilk and I   is incorrect, but I'm not sure about the former. I know it's neither an intensive or reflexive use, so I assume that it is incorrect, but any clarification in this regard would be appreciated.  Thanks for your time.  Edit: While the usage of "myself" has been adequately explained elsewhere, I just wanted clarification for this particular usage. I've heard it used frequently, but I couldn't find a grammatical basis for it. I apologise for the lack of clarity.


Why cannot fermions have non-zero vacuum expectation value?

In quantum field theory, scalar can take non-zero vacuum expectation value (vev). And this way they break symmetry of the Lagrangian. Now my question is what will happen if the fermions in the theory take non-zero vacuum expectation value? What forbids fermions to take vevs?


I just got done with my bachelors in Computer Science. After four years of CS, I realized I don't really like programming or anything to do with computers. I'd rather work for organisations which solve real world problems. Anyhow, I was wondering if I could get admission in Economics or international relations or something. Will I be able to get into a good university (I'm interested in European unis) and what future prospects would I have as a professional?


According to A Student's Introduction to English Grammar, Tense is defined as follows:     Tense. A system marked by verb inflection or auxiliaries whose basic use to locate the situation in time: I liked it (past tense, past time), I like it(present tense, present time).   However, the author also points out:     ..., English is not one of them: it has no future tense. It does have several ways of talking about future time, and the most basic one does involve the auxiliary will.   These two quotes made me puzzled because, as noted above, Tense is denoted by inflection or auxiliaries and the auxiliary will seems to clearly meet the criteria. In conclusion, my question is   Why doesn't the auxiliary will qualify as future tense?


is there a way to make multiple color along a path in illustrator

I have a curved path, I tried to duplicate it 3 times And play with the strokes and the offset, but the line crosses itself when there's a curve.  Is there A better way to make a multiple color along a path? Thanks for the help


How can I sort x,y co-ordinates from a list of dictionary?


Android sqlite database getallRows() checking for null gives error

I have tried all forms of error checking in order to catch and deal with the error checking but nothing works and it keeps crashing.   Cursor cursor = null;     try{      cursor  = mydb.getAllRows();     }finally{         if(cursor == null)         {             // I want to exit here and do nothing.              // Crashes here.           }         else{if(cursor.moveToFirst()){              do{                 String id= cursor.getString(0);                 String text = cursor.getString(1);                 String cooktime = cursor.getString(2);                 String difficulty = cursor.getString(3);                 String making = cursor.getString(4);                     }while(cursor.moveToNext());              }           cursor.close();          }      }   I know mydb has nothing in it, so how do I error check with this issue so it doesn't crash.   Error Log   12-03 14:54:21.259: E/AndroidRuntime(16766): FATAL EXCEPTION: main 12-03 14:54:21.259: E/AndroidRuntime(16766): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.exasmple.test/com.exasmple.test.List_of_recipes}: java.lang.NullPointerException 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2338) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.access$900(ActivityThread.java:148) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.os.Handler.dispatchMessage(Handler.java:99) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.os.Looper.loop(Looper.java:137) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.main(ActivityThread.java:5457) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at java.lang.reflect.Method.invokeNative(Native Method) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at java.lang.reflect.Method.invoke(Method.java:525) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:854) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:670) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at dalvik.system.NativeStart.main(Native Method) 12-03 14:54:21.259: E/AndroidRuntime(16766): Caused by: java.lang.NullPointerException 12-03 14:54:21.259: E/AndroidRuntime(16766):    at com.exasmple.test.List_of_recipes.onCreate(List_of_recipes.java:114) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.Activity.performCreate(Activity.java:5234) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302) 12-03 14:54:21.259: E/AndroidRuntime(16766):    ... 11 more   EDIT:  Thanks for the help everyone, I used a try catch method as suggested by  Nathan.  try{         Cursor cursor  = mydb.getAllRows();          // Do everything here      }catch (NullPointerException e){          // if caught then I do nothing and move on.      }   This stopped my problem from crashing instead of try{} and finally{}. The problem was also found within the .getAllRows() class call.


Permission not granted for creating file in /home

I am new to Ubuntu. I want to create a new dir in /home, lets call it myDir, and then I want to create a .txt file that outputs the current date. All these through terminal comands. So, to be more specific... I am in /home and I type   sudo -l #So I can type comands as superuser, I think. sudo -mkdir myDir #That works fine, the new directory is created, but    then.  sudo date > myDir/output.txt    It still does not give me any permission.  Someone might wonder, "You really have to create a new dir in /home?", well to tell you the truth, yes I do! Its a step from a school exercise and I am also really curious. I'am telling you so far I love ubuntu (installed 3 days ago) and if I can manage to fix a problem with my internet connection (one issue at a time) I am so gonna delete windows from my laptop!   Thank you in advance!


USB flash drive stuck in RO after DDing ISO

After I used dd to make a USB drive from an Ubuntu ISO, I am unable to format it for normal use. I ran: sudo dd if="ubuntu-16.04-desktop-amd64.iso" of="/dev/sdb" bs=4M  In order to create a bootable USB drive. However, after I was done with it, I wanted to format it as FAT32 and use it like a normal USB drive. No problem, should be easy, right? WRONG. I have tried:  Using the included Disks application to format it. It threw an error about corrupt GPT tables and wouldn't give me an override option. Using Gparted the erase the current partition table and write a new MBR table [completed successfully] After that I created a FAT32 partition spanning the entire volume, and remounted. [Showed up in Files, good so far] Attempted to copy a file to it. It thre an error saying the medium was read-only. Erased the partition table again in Gparted and this time created an NTFS partition spanning the entire disk. [Same RO error when attempting to copy a file onto it] Repeated the procedure trying this time with EXT4 [Same RO error] Repeated procedure trying a GTP table instead of an MBR table. {Same error]  Finally, I tried running: sudo hdparm -r0 /dev/sdb  And remounted. Still the same error. Keep in mind that I remounted it after formatting it each time. I am at a total loss. Has dd bricked my USB drive?


How to draw the phase portrait (integral curves) of a planar system of Differential Equations

I would like kindly to ask if there is any on the web, free plot engine for  a plane phase potrait? Thanks a lot.


I am pretty sure this story dates from the 1940's or 1950's. The first lunar expedition orbits the moon and discovers it is only a façade made of wood and canvas.


I had the beta drivers running previously and after a standard update it stopped working. What I've tried so far:  sudo apt-get remove --purge fglrx*   Then downloaded drivers from Amd website and unzipped it and ran:  sudo ./amd-driver-installer-catalyst-13-4-x86.x86_64.run --buildpkg Ubuntu/trusty sudo dpkg -i fglrx*.deb   After this the Ubuntu  guide wants to make this:  aticonfig --initial   and it returns:  Unable to open /etc/ati/control, please reinstall the driver. aticonfig: No supported adapters detected   The adapter is 280x and as said, it worked previously with the same drivers and with the same installation procedure.  Any ideas?


<script type="text/javascript">  var a = new Array( "Jane", "Tom,",  "Alan,", "Mary"); </script> <script type="text/javascript"> document.write(a[Math.floor(Math.random()*a.length)]); </script>  ate an apple     Is there away of reusing the answer to (a[Math.floor(Math.random()*a.length)]) later on in a script?     So for example I could later use text along the lines of Harry asked "answer" if they had enjoyed the apple


Unit Test is Providing 0% Coverage for Apex Trigger - Test class for trigger

trigger Splittrigger_newclass on Indexing__c (before delete,after insert) { list<C_Voyage__c> lstvoyage=new list<C_Voyage__c>();     list<string> q = new list<string>();     list<string> p = new list<string>();         //To store parent ids     list<id> IndIds=new list<id>();     for(Indexing__c Ind:trigger.old)     {         IndIds.add(Ind.id);         system.debug('inids>>>'+IndIds);     }       //Collecting all child records related to Parent records     list<C_Voyage__c> listVoyage=[select id,main_case_id__c from C_Voyage__c where Indexing__c in :IndIds];     system.debug('listVoyage'+listVoyage.size());     //deleting child records     delete listVoyage;      for(Indexing__c y:trigger.new)     {         system.debug('INdex>>>>>'+y);         if(y.Voyage_Created_Ref__c !=null)         {     p=y.Voyage_Created_Ref__c.split(',');     for (Integer i = 0; i < p.size();i++) {         C_Voyage__c tst = new C_Voyage__c();         tst.Voyage_Ref__c = p[i];         tst.Voyage_Type__c = 'Created';         tst.Indexing__c= y.Id;         tst.main_case_id__c= y.Case_Indexing_Ref__c;         lstvoyage.add(tst);         system.debug('listofvoyage>>>>>'+lstvoyage);     }    upsert lstvoyage;      if(y.Voyage_Amended_Ref__c !=null)     {      q=y.Voyage_Amended_Ref__c.split(',');      for (Integer j = 0; j < q.size();j++) {         C_Voyage__c atst = new C_Voyage__c();         atst.Voyage_Ref__c = q[j];         atst.Voyage_Type__c = 'Amended';         atst.Indexing__c= y.Id;         atst.main_case_id__c= y.Case_Indexing_Ref__c;         lstvoyage.add(atst);     }     upsert lstvoyage;     }     } } }


Prove that the sample variance equals $\frac{1}{2 n(n-1)} \sum_{j \neq k}\left(Y_{j}-Y_{k}\right)^{2}$

How to prove that the sample variance $S^2=\frac{1}{n-1} \sum_{j=1}^n\left(Y_{j}-\bar{Y}\right)^{2}$ is equal to $$\frac{1}{2 n(n-1)} \sum_{j \neq k}\left(Y_{j}-Y_{k}\right)^{2}?$$ I tried to write $Y_{j}-Y_{k}$ as $Y_{j}-\bar{Y}-(Y_{k}-\bar{Y})$, but I don't have idea what to do then.


Based on everything I've ever understood about Star Wars, it seems that Force users (even those with whom the Force is strong like Anakin and Luke) usually require significant training before being able to wield the Force even somewhat competently. Rey's ability to use the Jedi mind trick--even on a rank-and-file stormtrooper--without any training already seems to push the bounds of plausibility. Yet compared to her other Force exploits, this is seemingly one of her more mundane accomplishments.      Rey doesn't even really consider the possibility of being able to use the Force until Kylo Ren is already digging into her mind. Somehow, though, she is able to fight him off and even penetrate his own mind even though he is (apparently) trained in the Dark Side of the Force and she has barely even heard of the Force. She also decisively beats him in a lightsaber duel. How is this possible for someone completely untrained to defeat a trained Force practitioner? Was she really that strong? Is Kylo Ren really that weak?


How do I export a website to an app in safari? There is this feature in iOS 7 called 'save to home screen', I'm looking for something similar on OS X.


I can't use my outward flight ticket but need my return ticket. If I do not show on my outward flight, I am worried that the company might cancel my return flight. I have spoken to the flight company and they say I would have to cancel both tickets but the refund is so low, it's better to keep both tickets and not show for the outward flight. Should I tell the carrier that I am not going to use the outward ticket and pray they don't cancel my return flight.


Radius of convergence of $\sum_0^{\infty} n!x^{n^2}$

What can be said about the radius of convergence of the poower series  $$\sum_0^{\infty} n!x^{n^2}$$  I know that $\limsup_{n\to\infty}(n!)^{\frac1{n}}\to\infty$. Is that of any use here? Should I use ratio test or root test? Any hints? Thanks beforehand.


Does a spellcaster know when concentration ends?

Does a spellcaster know when concentration ends on one of their spells?  For example, when a wizard casts invisibility, that target is invisible until they attack or after one hour. So if the character attacks and the spell ends is the wizard aware that their spell that they are concentrating on ended earlier than expected?


I'm following  online.  At a point the author talks about "dynamic callback" to a function.  Could someone explain me what it is exactly because I didn't get it?


Sort the files by size retrieved from a series of folders

I retrieved all the pdfs in $HOME directory  $ find -E ~ -regex ".*/[^/].*.pdf"   It print more than 1000 files; I intent to sort them by size and searched   $ stat -f '%z' draft.sh 184   I drafts the script:  #! /usr/local/bin/bash  OLD_IFS=IFS  IFS=$'\n'  touch sorted_pdf.md  for file in $(find -E ~ -regex ".*/[^/].*.pdf") do     file_size=$(stat -c "%s" $file)     ....  done > sorted_pdf.md  IFS=OLD_IFS   It's hard to work them together and get my result. Could you please provide any hint?  I refactored the code   #! /bin/zsh OLD_IFS=IFS  IFS=$'\n'  touch sorted_pdf.md  for file in $(find -E ~ -regex ".*/[^/].*.pdf") do     # file_size=$(stat -c "%s" $file)     printf '%s\n' $file(DoL)  done > sorted_pdf.md  IFS=OLD_IFS   but get error report  $ ./sort_files.sh  ./sort_files.sh: line 12: syntax error near unexpected token `(' ./sort_files.sh: line 12: `    printf '%s\n' $file(DoL)'


How to create a seamlessly looping ocean

Is there a way animate the ocean modifier so it loops continuously?  I would like to make an animation where the last frame seamlessly goes into the first without the ocean "jumping":    How can I achieve this?


How to upgrade to ubuntu 17.04 from 16.04 using command line?

I want to upgrade my ubuntu to recent version which contains latest kernel 4.10. I saw following links.  and  but it didn't work.  How can I upgrade 17.04 from 16.04.2 in command line?


What do I call the ′ in mathematical formulae?

As in x′ = x + t  "Ex (?) equals ex plus tee".  In Russian it is called "штрих" (shtrikch).


Java: Array List Printing object reference instead of array

I'm am very much a rookie when it comes to coding. What I'm trying to accomplish is to load grades from a txt file and put them into an existing array.   I have actually solved this. and In the program the array does retain the values. But when I got to print them I get the object reference aka [I@5c647e05 rather than the array. Below is my code.     public static void main(String[] args)    {         int[] list = new int[15];         Scanner in = null; // create a scanner object         loadGrades(in, list);          System.out.println(list);     }      public static void loadGrades(Scanner in, int[] list) {          int grades; // int variable         try { // try                         in = new Scanner(new FileReader("Proj5Data.txt"));// change filename         } catch (FileNotFoundException ex) { // catch             System.out.println("File not found");             System.exit(1);         }         for (int i = 0; i < list.length; i++) {                          grades = in.nextInt(); // var                 list[i] = grades ;// put the int in the array at the counter value                     }         in.close();      }   Print results as:  [I@5c647e05 BUILD SUCCESSFUL (total time: 0 seconds)


zeros of derivative and increasing function

Let $f: \mathbb{R} \to \mathbb{R} $ be a differentiable function. Is it true that $f$ is strictly increasing on $\mathbb R$ if and only if $f'(x) \geq 0$ on $\mathbb R$ and the set $X = \{x \in \mathbb{R} \,| \, f'(x) = 0\}$ is countable?


I know this question is similar to "", but I do not consider it a duplicate because my interface is not named via a udev rule, and none of the other answers in that question worked for me.  So I have one WiFi adapter on this laptop machine, and I would like to rename the interface from wlp5s0 to wlan0:  root@aj-laptop:/etc/udev/rules.d# iwconfig wlp5s0    IEEE 802.11  ESSID:off/any             Mode:Managed  Access Point: Not-Associated   Tx-Power=off              Retry short limit:7   RTS thr:off   Fragment thr:off           Encryption key:off           Power Management:on  eth0      no wireless extensions.  lo        no wireless extensions.  root@aj-laptop:/etc/udev/rules.d# ifconfig wlp5s0 wlp5s0: flags=4098<BROADCAST,MULTICAST>  mtu 1500         ether 00:80:34:1f:d8:3f  txqueuelen 1000  (Ethernet)         RX packets 0  bytes 0 (0.0 B)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 0  bytes 0 (0.0 B)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0   However, there are no rules for this interface in 70-persistent-net.rules or any of the other files in the /etc/udev/rules.d/ directory.  Is there any way that I can rename this interface?


Does anyone have code to emulate a 16-bit input shift register with an ATtiny2313?

I would like to use an ATtiny2313 to emulate a Super Nintendo controller because I have an ATtiny2313 but I do not have an input shift register and I don't feel like soldering wires onto an existing SNES controller board.  This application requires 12 inputs (bits 13-16 are always 1) and a latch, clock, and data out pin.  Do you have this code lying around? It can't be more than 20 instructions.


Suggestion when you are browsing in the tags screen:  When you select a TAG, and then a question, when you press back button, back to select TAG again when should be to the questions about the TAG you selected previously as you do on the other options.


Who built the Jedi Temple on Coruscant? Both Canon and Legends answers are acceptable.


i have problem with open containing folder in ff/chromium instead instant open it open it minimized into launcher ( So the file explorer icon shake )  How can i force to open it instantly without minimizing it ?  Thank you for all help :)


In the code below, there is a Grid which contains points. Likewise, Element and Face also have points but I want to them to point to points in Grid.   Should I use smart or raw pointers. If I use smart pointers should I use std::unique_ptr or std::shared_ptr?  struct Vector3 {     vector <double> dim;      Vector3 ()     {         dim.resize(3);     } };  struct Element {     vector <Vector3*> points; };  struct Face {     vector <Vector3*> points; };  struct Grid {     vector <Vector3> points;      vector <Element> elms;     vector <Face> faces; };


I've a form when I click one radio button to load a subform. Ok this work perfectly, but has 3 selectors that I need external data when only this subform loaded. So, I did in this way:  $(document).on('focus', '#reemb', function () {     $.getJSON("/banks.php", function (json) {         $('#bank').empty();         $.each(json, function (i, obj) {             $('#bank').append($('<option>').text(obj.name).attr('value', obj.code));         });     });      $.getJSON('/statecity.json', function (data) {         var items = [];         var options = '<option value="">State</option>';         $.each(data, function (key, val) {             options += '<option value="' + val.name + '">' + val.name + '</option>';         });         $("#state").html(options);          $("#state").change(function () {              var options_city = '';             var str = "";              $("#state option:selected").each(function () {                 str += $(this).text();             });              $.each(data, function (key, val) {                 if (val.name == str) {                     $.each(val.city, function (key_city, val_city) {                         options_city += '<option value="' + val_city + '">' + val_city + '</option>';                     });                 }             });             $("#city ").html(options_city);          }).change();      }); });   This work fine, but everytime that I need to change one date the selectors clear and load again.  I tried to add tag onload to start the function to load selectors in this subform, but don't works. Also tried change events to .on, but also don't work. How I need to do this?   Thx!!


I recently have question that was downvoted and closed as "primarily opinion-based " I even got the "Peer Pressure" badge, I have immediately deleted my question, and  because of it, I've searched why my question is closed... I have viewed back my question and after navigating back to my profile, my reputation before I asked it is restored, I have viewed the delted question, the downvotes are still there but my reputation is restored. Are reputation restored on immediate delete on questions? Is this a feature?


Why should a voltmeter have a higher resistance than of any circuit element across which the voltmeter is connected?

According to my textbook, it is said that, for an ammeter:     It is essential that the resistance $R_A$ of the ammeter be very much   smaller than other resistances in the circuit. Otherwise, the very   presence of the meter will change the current to be measured.   Which makes definite intuitive sense to me. One would hope its resistance is very low, because otherwise it would be like trying to measure the speed of a car by putting spikes under its tires just before.   However, what it says for voltmeters is not intuitive for me:      It is essential that the resistance $R_V$ of a voltmeter be very much larger than the resistance of any circuit element across which the voltmeter is connected. Otherwise, the meter alters the potential difference that is to be measured.   Why would it having a small resistance cause a hamper on anything? Why does restricting the current of charge carriers a necessity in measuring potential difference in the circuit? This is coming from someone who is very unfamiliar with circuits in general, but trying to learn incrementally.


I am developing a Nodejs application that the user interacts with via HTTP on localhost. There are practically no parameters and the daemon has virtually no dependencies and it just needs to be up by log-in time.  I would like to follow the idioms on each platform for start-up scripts, and that means Upstart on Ubuntu and systemd on Fedora.   Are there any good tutorials for writing systemd system files? Are there any 'best practices' to be aware of?   I have found these resources:        I am mostly looking for an API of sorts as a reference, as well as a basic format to follow.


Unknown error: '' (“The cache has no package named wine1.6-i386”)

I'm using Ubuntu 16.04 LTS. The error:   Unknown error: '<class 'KeyError'>' (“The cache has no package named wine1.6-i386”)   keeps showing in the panel on the desktop. I installed wine some time ago to use only one specific program, but it never worked and I don't really need wine. So I just uninstalled the program as well as wine and hoped this would solve the problem, but it didn't.   I found other posts with a similar problem here, but those solve the problem by updating wine and I wanted to delete it from the system.  What does the error mean? Are there any processes that try to access wine or is it independent of the wine installation? What can I do about it?


My internal storage capacity is running low,  what can I do?

Currently, my internal storage is running low on space.    What can I do besides moving applications to the external memory, as to free up more space, but preserve my current applications and avoid uninstalling?  (Some of them won't be moved)


I need to convert a Particle System to a mesh object, so I can export it to Unity 3D. How could I do this?


Monte-Carlo simulation with sampling from uniform distribution

I used to work with Monte-Carlo simulations for a while. In my case, I generated random data for a variety of input parameters according to uniform distributions (with non-negative support), say for example two variables $a$ and $b$ where data is generated: $a_1, \dots, a_n \leftarrow U(1,2)$ and $b_1, \dots, b_n \leftarrow U(4,5)$.   Eventually, I evaluated a deterministic model $M$ for all generated pairs $(a_i,b_i)$ and calculate some statistics, like sample average of $\frac{M(a_1,b_1) + \dots + M(a_n,b_n)}{n}$.  Here is my question: What is the purpose of drawing random samples from the uniform distribution, rather than deterministically select $n$ equally distributed point from the interval $[1,2]$ and $[4,5]$ respectively and simply evaluate $M$ with those points? So, what would be the purpose of doing this stochastically rather than deterministically?


How can I replace a 4-way mechanical switch with occupancy sensor(s)?

There is a stairwell in our house, which is currently lit by a fixture controlled by three switches: a 4-way and two 3-ways. The wiring was done very recently and, I'm certain, in accordance to modern code (which may help you figure out the diagram, even if I don't know it).  I started with replacing the existing 4-way with a 3-way sensing switch from Lutron (). Predictably, one of the remaining mechanical switches stopped having any effect whatsoever. I was hoping, the second of the remaining mechanical switches will remain in control to allow explicit control of the light. This proved to be incorrect - sometimes it has an effect, some times it does not, and some times it disables the sensing switch (it clicks, but the light stays off).  While the new sensor works perfectly well detecting humans on the same floor, if a person descends the stairs from the upper floor, the light does not go on until one descends to the middle of the stairs - when the feet come to about the same level, where the sensor is.  So, it seems, I need either:   One occupancy sensor with a sensor looking up as well as sideways. This would, probably, be the easiest and most sensible option. It will let me remove the remaining mechanical switch.   or   Two occupancy sensors, that can work together - adding the second to where I currently have the semi-functional mechanical switch. This would provide the most complete sensor-coverage.   or   Figure out, what's wrong with the current setup - why is the existing mechanical switch misbehaving? I'm sure, I miswired something... Should I replace it with a 1-pole switch now, that I only have 2 switches on the circuit?   Update:  So I tried to follow  linked to by mac and found it easy to connect the sole red wire on the 3-way mechanical switch to one of the black wires.  Unfortunately, that did not improve the situation much. Depending on the position of the (newly rewired) mechanical switch, the sensor either works or it does not.  I'm certain, I mis-wired the sensor when replacing the old 4-way switch with it. Could somebody set me straight, please?  In addition to ground, there were four wires connected to the 4-way switch (duh!): two red on one side, and two black on the other. The new switch has 3 connectors: one blue and two black. What do I connect to what?


How to modify itemize vertical spacing within blocks in beamer?

I have noticed that when I have "itemize" environments defined within blocks in beamer, that they introduce more vertical spacing between the top and the bottom of the blocks, than vertical text. Since I have a slide with some text filled blocks and directly after, a slide with only "itemize" holding blocks, I would like the spacing between the itemized text and the block to be the same as for regular text.   On  I have read about "squeeze" option, but it doesn't seem to work...   Additional info:  The problem is in the additional vertical space that is included by the "\itemize" environment. I have found  on how to remove vertical spacing from the itemize list, and I am using this approach. However, it is a brute force approach. What I would like to know if it is possible to have the same vertical space between the end of the itemize list and the bottom of a block, as the one set between the normal text and the bottom of the block.   MWE:   \documentclass[10pt]{beamer} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{exscale} \usepackage{epsfig} \usepackage{fancybox} \usepackage{lmodern} \usepackage[T1]{fontenc} \usepackage{overpic}  \usepackage{multimedia}  \usetheme{default} \usecolortheme{crane}  % -- Modifications that enable the footline and set black color for the fonts  \setbeamertemplate{footline}{%     \begin{beamercolorbox}[wd=\paperwidth,ht=2.25ex,dp=1ex,right, rightskip=1mm, leftskip=1mm]{titlelike}         \textcolor{black}{             %\inserttitle\hfill\insertauthor\hfill\insertframenumber%             Something\hfill Something Else \hfill\insertframenumber%         }     \end{beamercolorbox} }  \setbeamertemplate{itemize items}[square]  \setbeamercolor{item}{fg=black} \setbeamercolor{frametitle}{fg=black} \setbeamercolor{block title}{fg=black} \setbeamercolor{title}{fg=black} \setbeamercolor{block body}{bg=white}  % END Modifications  \begin{document}   \begin{frame}   \frametitle{text blocks}     \begin{block}{block}         block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   blockk     \end{block}{block}      \begin{block}         block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block     \end{block}     \begin{block}{block}         block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block   block     \end{block} \end{frame}  \begin{frame}   \frametitle{itemize blocks}     \begin{block}{item}         \begin{itemize}             \item item              \item item              \item item         \end{itemize}     \end{block}     \begin{block}{item}         \begin{itemize}             \item item              \item item              \item item         \end{itemize}     \end{block}     \begin{block}{item}         \begin{itemize}             \item item              \item item              \item item         \end{itemize}     \end{block}   \end{frame}  \end{document}


Make a duration bar and a button that shows how much you have corrected

I want this so that on Feed I can see how much I have to wait and, if for example it shows me that I have been banned then on duration bar will show if I’m banned temporary or permanent. On temporary it shows the count down and make the count down to start when all the posts are 100% corrected.   And make for each user to have on each posts percentage button which shows: dark which means bad, yellow which means good and green which means green, 100% correct post.  And when a user writes an answer or a question, then it will show a bar with colors that have a line and the line will move according to how much you have corrected. Because, I really need to know wether I’m banned permanently or not.   What do you think about that?


Animation in blender: How to link restrict visibility with restrict viewport rendering

I have created an assembly sequence and the viewport visibility of the components have been restricted along the animation. BUT I forgot to retrict the viewport visibility as well :(  Now I would like to link the viewport visibility with the viewport rendering only without affecting the rest of my animation. Is there any way to do this?   This script in the console doesn't create link:  "for ob in bpy.context.scene.objects: ob.hide_render = ob.hide" ; is there a script that would enable this?


Which Wi-Fi channel should I use for my Wi-Fi?

which channel is the best fit for my Wi-Fi?  I'm the one on channel 7.


PHP getting all occurrence in single line

is this a limitation on any regex result? What I need is to get all the occurrence in a single line, but preg_match_all return the first and end of the expression. Is there any other way to get all the occurrence on the line?  $re = "/(media|images)(.*)(.jpg|.jpeg|.png)/"; $str = 'images/test/test-1.png" alt="test-1" />                Array         (             [0] => images/test/test-1.png" alt="test-1" />                Array         (             [0] => images         )      [2] => Array         (             [0] => /test/test-1.png" alt="test-1" />                Array         (             [0] => .png         )  )


PCA on Wine data with only one binary data(white/red wine) and other quantitative data

I am working on wine data with the following format:  head(wine,2)      ID color fixed.acidity volatile.acidity citric.acid residual.sugar chlorides free.sulfur.dioxide 1 2419 white           6.6             0.56        0.22            8.9     0.034                  27 2  285   red           9.9             0.59        0.07            3.4     0.102                  32   total.sulfur.dioxide density   pH sulphates alcohol quality 1                  133 0.99675 3.20      0.51     9.1       5 2                   71 1.00015 3.31      0.71     9.8       5   I want to do a PCA on the data but I am wondering how to deal with the binary categorical data here. I know this issue has been talked a lot of times but I'm trying to understand what is the simple way to deal with this particular data. My ultimate plan is to predict wine quality by combining local kernel method and PCA


Let there be an imaginary digital lock that verifies a simple 4-digit passcode (in base 10 numbers, like 4281 or 3349, etc.)  BUT unlike other locks, it does not reset after a failed trial. That means if you enter 1823917 consecutively, you have in effect tried 1823, 8239, 2391, and 3917 (if it were a traditional lock) i.e. If the passcode was 8239, it would open after you enter 18239. Since it requires fewer guesses, I suppose it's not so good of a lock in terms of security, but as a question out of pure curiosity:  What would be the most efficient method to opening this lock (the pattern of entering the numbers)  and how many numbers would you have to input in order to guarantee success?


Treat Close Votes review the same as Suggested Edits review

When an edit is suggested to a post, it's noted in the following way:    If you are able to use the Suggested Review queue, clicking on edit (1) takes you directly to the review queue location where you can perform your review.  Can the same be done for those able to review the Close Votes review queue? That is, when you click on the close (1) button at the bottom of the post    it takes you to that specific entry in the review queue.  This has the added benefit of leaving the reviewer in the Close Votes review queue where other clean-up might be required.


Is "Does" or "Did" dropped when it occurs at the beginning of a sentence?

I watch a lot of American shows and I noticed that the actors tend to drop "does" or "did" from the dialogue when a sentence begins with it. For example: Does she have a name? becomes She have a name? Did you do it? becomes You do it? Not sure if this is a common occurrence in other cultures as well. I wanted to know if this is a general rule in english to verbally drop the "does" or "did" when a sentence begins with it.


Floating sidebar clash with footer in team page

Here is a screenshot from  page, with the floating sidebar: (all good so far)        After I scroll down to footer it just combines both:        Can it please be fixed?


Cardinality of a set of closed intervals

What is the cardinality of the set S of all closed intervals on the real number line with rational (positive) lengths?  I believe the number of intervals with a specific fixed length but varying start points is |R|, and the number of intervals with a fixed start point but varying lengths is |Q| = |N|. I think the answer to the question would then be |S| = |R x N| = |R|? I'm not quite sure how to prove the last equality though. Would I have to define a bijective function that maps elements of (R, N) to R? How would I approach doing so?


- but IMHO there has to be a simpler solution. If num-lock is on in the BIOS - why is it turned off during linux boot and/or KDE/Gnome/whatever startup?


For finite group $G$ of order $n$ such that there exists a unique subgroup of order equal to each positive divisor of $n$. Is it necessarily cyclic?

Let $G$ be a finite group of order $n$. Suppose $k$ is a positive integer such that $k|n$, then there exists a unique subgroup of order $k$.   Is it necessarily cyclic?  If $G$ is Abelian, then I can prove it, but if $G$ is nonAbelian, then it is difficult to me to prove or disprove.


I was reading in the comments of this question: , and came across the term 'signal-to-unicorn ratio' and I have been unable to find out what it means.  Can anyone explain it?


Can I get around a Pokemon copyright with new art and minor changes?

If I develop a game that is essentially pretty much Pokemon (you're a trainer, you catch "monsters" and put them to fight and level up etc), and I do the next things:   I'm a trainer with a 6-"Monsters" party. Mechanics like the PC, Gym Leaders and "tall grass" will be used. I will throw an "ball" to catch the weakened "monster". I will use common item names, like "potion", "high potion". The battles are almost the same as Pokemon in terms of mechanics (four moves, elements, critical, evasion etc) I will NOT use Pokemon names nor graphics... artwork is mine. Some of the attack names will match Pokemon attack names. I think it is okay, like "ember". Come on.   With all these points, I shouldn't run into copyright issues or anything right? Even if the game feels a lot like Pokemon itself?


iPhone tethering not working via bluetooth

I can successfully tether my Mac (10.7.3) to my iPhone4 (5.0.1) via wifi, no problem, been doing it for months.  However, when I try to tether via bluetooth instead, I can't seem to see the internet from my mac.  Network Settings reports a green light for Bluetooth PAN, but my browser can't connect to anything at all.  My Mac reports very similar IP addresses for both, starting with 172.20.10 and differing only in the last octet.  Any idea why I can't successfully tether via bluetooth?


Does mass dilate in general relativity. For example if I was accelerating will my mass dilate?  Thanks


What is the difference between a "singular noun" and a "plural noun treated as singular"?

I'd always thought that words like "physics" and "mathematics" were singular: after all, we say "physics is the study of…" etc. But apparently, according to the the comments , each of these words is actually a "plural noun [usually treated as singular]":   (highlighting/ellipsis added by me) (NOAD = New Oxford American Dictionary)  One, Is this categorization valid? That is, is it correct to say, as the NOAD does, that these words are indeed plural (but treated as singular), rather than to say that they are singular? The accepted answer on that question, by user RegDwigнt, has a different analysis that speaks in terms of “news” being "uncountable", "used with singular verbs", and "etymologically, it used to be a plural form", and thereby carefully avoids addressing this issue, of whether these nouns are indeed plural-treated-as-singular. So my question remains.  Two, If so, what makes these words plural? Is it the fact that they end in s? (Surely "bus" is not plural?) Is it history? (Were they used as plural at some time? How far back in history does one go to decide whether a noun is singular or plural?) Is it the fact that they don't have any distinct forms treated as plural?  Most importantly, why do we even have a grammatical category of "plural nouns treated as singular"? What purpose does it serve, and how are such nouns functionally distinguishable from nouns that are actually singular? When/if the reason is history, is there a rationale for saying "plural nouns treated as singular" rather than "singular nouns that were formerly plural"?  Edit: My question isn't just about "-ics" words, but all words in the category "plural nouns treated as singular" (assuming that the category isn't just -ics words).  Edit 2: The image and part "One" of the question were added later; previously I took for granted that the categorization was valid.


How to handle a column named table in database table

I am currently working with Joomla. I want to insert a new row into #__content_types table, but there is a column named table that is currently giving me errors. How do I insert the data despite the name of the column 'table'? INSERT INTO #__content_types(type_id, type_title, type_alias, table, field_mappings) VALUES ('14','SVG Image','com_view_vv.form','{"special":{"dbtable":"#__table","key":"id","type": "Corecontent","prefix":"JTable","config":"array()"},"common":{"dbtable": "#__ucm_content","key":"ucm_id","type":"Corecontent","prefix":"JTable","config":"array()"}}', '{"common": {"core_content_item_id":"id","core_title":"name","core_alais": "alias"},"special":{"imptotal":"imptotal","impmade":"impmade","clicks": "clicks","clickurl": "clickurl","custombannercode":"custombannercode","cid":"cid","purchase_type": "purchase_type","track_impressions":"track_impressions","track_clicks":"track_clicks"}}');


Near, near to and nearby. What's the difference?

Why isn't near, near to and nearby always interchangeable?    They can precede the noun.     I live nearby the railway station     I live near the railway station    I live near to the railway station   When they are adverbs they can follow noun +  be   The railway station is nearby (my house) The railway station is near my house The railway station is near to my house   But we don't normally say:     ?Meet me at the near railway station   or    ?Meet me at the railway station near (to)   The accepted version is:     Meet me at the railway station nearby   Meet me at the nearby railway station   Why?


Show that $\sum_{n=1}^\infty r^n\cos(n\theta)=\dfrac{r\cos\theta -r^2}{1-2r\cos\theta+r^2}$ whenever $0<r<1$.

Note I have seen that this question has already been posted but I believe my concerns with the question have yet to be answered.  Question: Write $z=re^{i\theta}$, where $0<r<1$, in the summation formula $$\sum_{n=0}^\infty z^n=\dfrac{1}{1-z}$$ whenever $|z|<1$. Then, with the aid of the following theorem,     Suppose that $z_n=x_n+iy_n$ ($n=1,2,\dots$) and $S=X+iY$. Then   $$\sum_{n=1}^\infty z_n=S \text{ if and only if }\sum_{n=1}^\infty x_n=X \text{ and } \sum_{n=1}^\infty y_n=Y$$   show that  $$\sum_{n=1}^\infty r^n\cos(n\theta)=\dfrac{r\cos\theta -r^2}{1-2r\cos\theta+r^2} \text{ and } \sum_{n=1}^\infty r^n\sin(n\theta)=\dfrac{r\sin\theta}{1-2r\cos\theta+r^2}$$ whenever $0<r<1$.  Proof: Let $z=re^{i\theta}$, where $0<r<1$. Recall $$\sum_{n=0}^\infty z^n=\dfrac{1}{1-z}$$ whenever $|z|<1$. Replace $z$ by $re^{i\theta}$ in the summation.  $$\sum_{n=0}^\infty \left(re^{i\theta}\right)^n=\sum_{n=0}^\infty r^ne^{i\theta n}=\dfrac{1}{1-re^{i\theta}}$$ whenever $\left|re^{i\theta}\right|<1$. Replace $e^{i\theta}$ by $\cos\theta +i\sin\theta$.  \begin{equation*} \sum_{n=0}^\infty r^ne^{i\theta n} =\dfrac{1}{1-r\cos\theta-ir\sin\theta} =\dfrac{1-r\cos\theta+ir\sin\theta}{((1-r\cos\theta)-ir\sin\theta)((1-r\cos\theta)+ir\sin\theta)}=\dfrac{1-r\cos\theta+ir\sin\theta}{(1-r\cos\theta)^2+(r\sin\theta)^2}=\dfrac{1-r\cos\theta+ir\sin\theta}{1-2r\cos\theta+r^2\cos^2\theta+r^2\sin^2\theta}=\dfrac{1-r\cos\theta+ir\sin\theta}{1-2r\cos\theta+r^2} \end{equation*}  whenever $\left|re^{i\theta} \right|<1$.   Replace $e^{i\theta n}$ by $\cos(n\theta)+i\sin(n\theta)$.  $$\sum_{n=0}^\infty r^n(cos(\theta n)+i\sin(\theta n))=\dfrac{1-r\cos\theta}{1-2r\cos\theta+r^2}+i \cdot \dfrac{r\sin\theta}{1-2r\cos\theta+r^2}$$ whenever $\left|re^{i\theta}\right|<1$.   By the theorem, we have the next two sums:  $$\sum_{n=1}^\infty r^n\cos(n\theta)=\dfrac{1-r\cos\theta}{1-2r\cos\theta+r^2}$$ and $$\sum_{n=1}^\infty r^n\sin(n\theta)=\dfrac{r\sin\theta}{1-2r\cos\theta+r^2}$$ whenever $\left|re^{i\theta}\right|<1$.  So my questions are:    How can I get $1-r\cos\theta$ to become $r\cos\theta -r^2$? What do I do with the $n=0$ term of both sums?


Russian (Czech, Polish, etc.) tradition of equations breaking

According to the Russian (Czech, Polish, etc.) typesetting tradition, we have the following rules of equation breaking:  If an equation cannot be fit into one line, a typesetter should put part of the equation to the next line. First of all, breaking is allowed on binary relation symbols (=, <, etc.) and signs +, -. In the second place, breaks are allowed on multiplication signs (not on divisions!). The symbol where the break was done should be repeated in the beginning of the next line. The "x" sign should be used in case of break in multiplication.  The question is how to achieve this behaviour. As one can see, it's not an issue for displayed equations since breaking is always done manually. Interesting part are embedded equations which LaTeX can break without repeating the sign of operation. Possible yet conservative solution is to turn off equation breaking inside paragraph at all. Unfortunately this could cause too large spaces between words.


As a 10k user, how do I ignore deleted answers?

I just became a 10k user over at maths.SE, and now I see deleted answers, but I don't want to see them. (They're distracting.)  How do I ignore deleted answers? If there's not already a non-contrived way of achieving this, would it be possible to add a "[.] hide deleted answers" switch in the prefs tab (or something similar)?


I'm trying to do a number checker in imessage. We all know that there is no such api, so I'm trying to use the tools at hand. The main took with past issues on this site on this topic.  I made a loop that inserts a number into a string, and by the color of the number (blue - registered, red - missing), using the standard utility Digital Colors Meter determines the color of the number. Then, depending on the color, it either adds a variable with a number from the initial txt file to the new one, or starts the script from the beginning. At least it should be.  But something is going wrong in loop. It checks the color, inserts numbers, everything is fine, but apparently the wrong condition, apparently the wrong data types. It inserts different numbers into the scatter. Some will insert, some will not, regardless of the initial condition. What could be the reason? Where is the error?      tell application "Digital Color Meter" to activate     tell application "System Events"         tell process "Digital Color Meter"             click menu item 1 of menu 1 of menu bar item 4 of menu bar 1         end tell         do shell script "/usr/bin/python -c \"import objc;bndl = objc.loadBundle('CoreGraphics', globals(), '/System/Library/Frameworks/ApplicationServices.framework');objc.loadBundleFunctions(bndl, globals(), [('CGWarpMouseCursorPosition', 'v{CGPoint=dd}')]);CGWarpMouseCursorPosition((" & 1002 & "," & 222 & "));\""         set rgbColors to words of (the clipboard)     end tell     if rgbColors is equal to {"77", "39", "38"} then         exit repeat     else         do shell script "echo " & quoted form of n & " >> /Users/oneone/Desktop/base2.txt"     end if   Only the color check condition for Digital Color Meter is presented here.  Through the do shell, the color is read at the mouse position and the variable is added to the new file.


Prove that $\lim_{n \to \infty}(a^n + b^n+c^n) ^{(1/n)} = \max \{a,b,c\}$, for $a, b, c > 0$

Prove that $\displaystyle\lim_{n \to \infty}\left(a^{n} + b^{n} +c^{n}\right)^{1/n} =  \max\left\{a,b,c\right\}$ for $\displaystyle a, b, c > 0$.


Is it possible to de-bevel all or parts of a mesh?

Is there an easy way to un-bevel parts of a mesh that have been beveled? e.g. Convert this:  into a normal cube? Edit: Is this possible with perhaps some trick of calculating where the original edge was and collapsing all the selected edges to that point? (python?)