can't type lower cased e in amazon ec2 (Amazon Linux)

After a few days of operation on my new ec2 build, the following happens:   I log into SSH, everything is fine, I do my coding I return the next day, and log into SSH I cannot type a lower cased e anymore--I get the error ding when I type it I try to ssh from a different computer, same problem I reboot the server, same problem I open nano or vi and e works fine, just not in bash or sh I terminate the server, create a new one, install from scratch, a few days later it happens again   This is baffling! Where do I even start to troubleshoot?  My Local Machine Setup(s):   windows XP or 7 putty (latest) or cygwin/openssh   The EC2 setup   Amazon Linux (default options) node.js iptables forwarding port 80 to node on port 8003 emacs, npm, and openssl-devel no other mods       Output of stty -a while I can't type an e  sh-4.1$ stty -a speed 38400 baud; rows 30; columns 95; line = 0; intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0; -parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts -cdtrdsr -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff -iuclc -ixany -imaxbel -iutf8 opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke   In case it helps someone else with a similar issue, I created a script (called sub) to convert upper-cased E to lower-cased, then echo the command back. Then I run it in backticks to get an e on the command line::  #!/bin/sh echo ${@//E/e}  > `sub Emacs /Etc/profilE`   UPDATES   This breaks for all users In bash only (csh works fine) In emacs edit mode only   I've created  and hone in the solution.


Object doesn't recognized, how to solve?

I have a simple code to work with getters and setters. I have created a object from book class in another class. But this object doesn't recognize by the class. Why is that? I get this error      An object reference is required for the nonstatic field, method, or property 'member'              class Book {     private int num;      public void setNum(int no)     {         this.num = no;     }           public int getNum()     {         return this.num;     }   }  class Program {     Book bb = new Book();     public static void Main()     {         bb.setNum(10);         Console.WriteLine("Insert value" + bb.getNum);     } }


QGIS DEM (Terrain models) Mode Slope creates wrong data

I have a DEM raster file downloaded from the . The file can be downloaded .  I am trying to create a slope raster in percent with the DEM tool in QGIS. The GDAL command is the following:  gdaldem slope /Users/Downloads/n41w107/imgn41w107_13.img /Users/Downloads/slope.tif -p -s 1.0 -b 1 -of GTiff   The tool runs fine, but the created file slope.tif has strange data. The statistics for the band are the following:  STATISTICS_MAXIMUM=29834248 STATISTICS_MEAN=1845376.751065 STATISTICS_MINIMUM=0 STATISTICS_STDDEV=1658350.0283881   So they are obviously way to big for percent. What am I doing wrong?    Update: I calculated the Slope in degrees and got the following statistics:  STATISTICS_MAXIMUM=89.999809265137 STATISTICS_MEAN=89.583139343302 STATISTICS_MINIMUM=0 STATISTICS_STDDEV=5.9592219763749   A mean of 89 degrees seems really high to me. Is that reasonable?


I would like to create a command that ends a beamer frame. However, this leads to the error message quoted below - probably due to the same problem that prevents indentation of frame commands, cf. .  The error message is: ! File ended while scanning use of \next.  Below is a failing MWE that can be made working by commenting out \end{frame} in the definition of \pfooter plus uncommenting it at the bottom.  \documentclass[english,10pt]{beamer}  \usepackage{listings}  \newcommand{\pheader}[1]{%     \section{bla: blabla}     \begin{frame}[fragile]{blabla} }  \newcommand{\pfooter}{\end{frame}     % some other commands }  \begin{document} \pheader{}   \begin{lstlisting}[gobble=4]     1234567890   \end{lstlisting}    bla \pfooter{} % \end{frame} \end{document}


Can I use perfect infinitive for future plans?  For instance: It will be fun to have travelled with you during next week.  Is it grammatically correct?


Similes and Metaphors - are similes a subset of metaphors?

I've always been taught that metaphors and similes both draw a parallel between two disparate ideas/thoughts/objects, but that a simile is a more explicit comparison using the word "like" or "is", whereas a metaphor's connection is more implicit. For example, "His injured ankle burned like a hot stove" is a simile, where as, "His injured ankle was a hot stove of pain" is a metaphor.  However, I recently heard a colleague note that similes are nothing more than a special kind of metaphor. In other words, all similes are metaphors. This seems to contradict what I was always taught (and , for what that's worth). Can anyone straighten me (or my colleague) out?


How do you embed iFrame content into a CartoDB infoWindow?

All,  I'm trying to embed Youtube videos and SoundCloud audio clips into a CartoDB infoWindow. I'm trying to do this by simply using the {{embed}} column and entering it into the custom infoWindow html...
   x

name

{{name}}

description

{{description}}
                 {{embed}}

   To see the result, click one of the two point features in the map:  Result Map:     SoundCloud embed code:     Youtube embed code:


Corrupted JPG has undesired color bars overlay

I have transferred photos from my camera SD card to my computer (using a card/ram reader) and deleted the original photos. Now I have just realized there are color bars overlaid in photos. Here is an example:    You can download the original image (which includes metadata) here. Note that the colorbars are not present in the thumbnail!:     The blame seems to be on the transfer. Do you agree? Why transferring a photo can potentially corrupt it? I haven't seen this problem with other file types.  As I don't have the original photos, there any way to fix/reduce this corruption?


Why don't languages raise errors on integer overflow by default?

In several modern programming languages (including C++, Java, and C#), the language allows  to occur at runtime without raising any kind of error condition.  For example, consider this (contrived) C# method, which does not account for the possibility of overflow/underflow.  (For brevity, the method also doesn't handle the case where the specified list is a null reference.)    //Returns the sum of the values in the specified list. private static int sumList(List<int> list) {     int sum = 0;     foreach (int listItem in list)     {         sum += listItem;     }     return sum; }   If this method is called as follows:  List<int> list = new List<int>(); list.Add(2000000000); list.Add(2000000000); int sum = sumList(list);   An overflow will occur in the sumList() method (because the int type in C# is a 32-bit signed integer, and the sum of the values in the list exceeds the value of the maximum 32-bit signed integer). The sum variable will have a value of -294967296 (not a value of 4000000000); this most likely is not what the (hypothetical) developer of the sumList method intended.  Obviously, there are various techniques that can be used by developers to avoid the possibility of integer overflow, such as using a type like Java's , or the  keyword and  compiler switch in C#.  However, the question that I'm interested in is why these languages were designed to by default allow integer overflows to happen in the first place, instead of, for example, raising an exception when an operation is performed at runtime that would result in an overflow.  It seems like such behavior would help avoid bugs in cases where a developer neglects to account for the possibility of overflow when writing code that performs an arithmetic operation that could result in overflow.  (These languages could have included something like an "unchecked" keyword that could designate a block where integer overflow is permitted to occur without an exception being raised, in those cases where that behavior is explicitly intended by the developer; C# actually .)  Does the answer simply boil down to performance -- the language designers didn't want their respective languages to default to having "slow" arithmetic integer operations where the runtime would need to do extra work to check whether an overflow occurred, on every applicable arithmetic operation -- and this performance consideration outweighed the value of avoiding "silent" failures in the case that an inadvertent overflow occurs?  Are there other reasons for this language design decision as well, other than performance considerations?


Which command controls the open file limits?

Which command / configuration file controls the open file limits on OS X?  Is there a different command for OS X 10.5 / 10.6 / 10.7?  The options I explore below are ulimit, sysctl, and launchctl  "Too many open files" is apparently a common error on Leopard, perhaps other versions of OS X:        There are many (related?) ways to view the open file limits:  $ ulimit -a core file size          (blocks, -c) 0 data seg size           (kbytes, -d) unlimited file size               (blocks, -f) unlimited max locked memory       (kbytes, -l) unlimited max memory size         (kbytes, -m) unlimited open files                      (-n) 2048 pipe size            (512 bytes, -p) 1 stack size              (kbytes, -s) 8192 cpu time               (seconds, -t) unlimited max user processes              (-u) 512 virtual memory          (kbytes, -v) unlimited   $ launchctl limit cpu         unlimited      unlimited       filesize    unlimited      unlimited       data        unlimited      unlimited       stack       8388608        67104768        core        0              unlimited       rss         unlimited      unlimited       memlock     unlimited      unlimited       maxproc     1024           2048            maxfiles    2048           4096         $ sysctl -a | grep files kern.maxfiles = 32768 kern.maxfilesperproc = 16384 kern.maxfiles: 32768 kern.maxfilesperproc: 16384 kern.num_files: 2049   It has been claimed in some of the above posts that these can be modified with the following commands:  sudo launchctl limit maxfiles 16384 32768 sudo ulimit -n 32768 sudo sysctl -w kern.maxfilesperproc=16384 sudo sysctl -w kern.maxfiles=32768   However, out of the above commands, only the sysctl commands have any apparently effect (i.e. ulimit -n and launchctl limit show no change after the above commands have been entered, while sysctl -a does show the requested changes).  The corresponding locations to change these parameters for the OS are:  /etc/sysctl.conf /etc/launchd.conf   I also discovered one  which reads that ulimit only controls the current shell.  How can I adjust upwards the max files / max open files limits on macOS?


Method Chaining Won't Work for the dynamically created element in JQuery

I have 3 input fields inside a table row that are needed to validate on the client-side without pressing the submit button:     <input name="clr" type="number" class="form-control" min="27" step="any"> 	    <input name="litre" type="number" class="form-control" min="0.5" step="any"> 	    <input name="fat" type="number" class="form-control" min="3.0" max="7.0" step="any"> 	   So I attach blur and invalid events. I also need to attach those two events on the dynamically created input fields.   Below code is work for static input fields:  $('input[name="clr"], input[name="litre"], input[name="fat"]').on('blur', function(event) {   event.target.checkValidity();   $(event.target).removeClass("errorClass"); }).on('invalid', function(event) {   setTimeout(function() {     $(event.target).focus().addClass("errorClass");   }, 50); });   For dynamically created elements I tried this code:  $(document).on({     'blur': function(event) {       event.target.checkValidity();       $(event.target).removeClass("errorClass");     },     'invalid': function(event) {       setTimeout(function() {         $(event.target).focus().addClass("errorClass");       }, 50);     }   },   'input[name="clr"], input[name="litre"], input[name="fat"]' );   BUT this won't work!   Can anyone give me suggestion how can I overcome this problem?  EDIT: Heres, how I created the dynamically elements:  let clrTd = '<input name="clr" type="number" class="form-control" min="27" step="any">	'; let litreTd = '<input name="litre" type="number" class="form-control" min="0.5" step="any">	'; let fatTd = '<input name="fat" type="number" class="form-control" min="3.0" max="7.0" step="any">	';  $(document).on('blur', 'input[name="code"]', function () {     if ($(this).closest("tr").is(":last-child") && $(this).val() != '') {         var markup = "
" + clrTd + litreTd + fatTd + "
 ";         $("#editableTable tbody").append(markup);     } });


What's a better way to make this insert more secure and safe from injection and manipulation

I've been trying to put together functions in a more secure way that keeps us safe from injection or manipulating inserts by calling different columns to be updated. In your opinion, is this function safe at all, and if not what would you suggest is a better way to do it, and why. This function is called when a user updates their profile, or specific parts of their profile, as you can see I've made an array with items which is all they can update in that table. Also, the user_id I am getting is from the secure encrypted JSON token that's attached to their session, they are not sending that. Thanks for your time. function updateProfile( $vars, $user_id ) {     $db = new Database();     $update_string = '';     $varsCount = count($vars);     $end = ',';     $start = 1;     $safeArray = array( "gradYear", "emailAddress", "token", "iosToken", "country",  "birthYear", "userDescription" );     foreach($vars as $key => $value) {         if(in_array( $key, $safeArray )) {             if($start == $varsCount) {                 $end = '';             }                       $update_string .= $key . '=' . '"' . $value . '"' . $end;         }             $start++;     }      if($start > 0) {         $statement = "update users set " . $update_string . " where userId = '$user_id'";         $query = $db->updateQuery( $statement );         if($query) {             $response  = array( "response" => 200 );         } else {             $response  = array( "response" => 500, "title" => "An unknown error occured,  please try again");         }      }


How many Valyrian steel swords are there at the beginning of GoT, and who owns them?

As of 298 AL, where A Game of Thrones  begins, where were the various Valyrian steel weapons that exist?  That is to say, before the 1st chapter starts. The swords are already in someone's hands at the beginning. I just want how many and who owns them. I don't want to know how they pass to new owners as the story progresses.


How are setuid, suid, sudo, and su all related?

I have a feeling the setuid bit, the nosuid mount option, sudo, and su are all related given their names.  But how do they relate to one another?  Are some of them used in conjunction?   If they are not, then why are their names so similar?


Has average response time changed since The Firing, and if so, by how much?

What leads me to ask: I requested assistance with a thorny problem via the "Contact Us" on Nov. 6.  No answer; tried again on Nov. 17.  Still nothing (December 8).  How many SOS's are there in the current backlog?  What's the average wait time to get a response from "Contact Us"?  How many SOS's are received per week?  How do those numbers compare with those that were occurring prior to The Firing?  Is average wait time calculated and recorded?  If so, how could I look at it?  Has the data guru been looking at these issues at all?  Have the community managers and/or management noticed or hypothesized a correlation between reduction of wait time and the general level of trust?  And now, two feature requests:   When a user sends a message to the CM team via "Contact us" or an email to community-support@stackoverflow.com, arrange for the automatic response to include an estimated number of days of wait time. Publish somewhere (here perhaps) the average wait time on an occasional, on-going basis, e.g. approximately once a month.     How this question is different from the proposed duplicate:  The proposed duplicate seems to be saying that average response time is between one day and one week, and that if it's going to be longer, one can expect an email to that effect.  In these difficult times, I'd be surprised if the numbers were the same.  I'd like to know how they compare.  My target answer author: the data guru, I forget her name (hope someone will help me and edit this part).


Developing for Ubuntu tablet using Python

I want to start developing for the Ubuntu tablet, but I don't think that I can use python with the SDK. I heard that you can make games with Python in Blender and I wanted to know if there was a quick and easy way to port games from Blender onto the Ubuntu phone platform and how to do it. If there isn't, are there other ways to make games using Python for the Ubuntu tablet?


sed command – sed 's/test/toast/' – not replacing all 'test' in file

Shouldn't the second 'test' line also get replaced? How would I have to write the command to replace all 'test'? $ sed 's/test/toast/' texttest.txt  toast file test file hahahaha 1 toast file test file hahahaha 2


I want to write an algorithm for two circles intersection and touching cases . How can I do it with a quadtratic equation?

Given that two circles with coordinates (x1, y1) and (x2, y2) and radius r1 and r2 respectively . I need to find an equation , which can be used in code to to find the coordinates and the presence of touching and intersection .  Like Ay2 +  By + C = 0 .     Circle 1 (x - x1)2 + (y - y1)2 = R1 * R1   Circle 2 (x - x2)2 + (y - y2)2 = R2 * R2


Inappropriate review audit answer for "FTPS versus SFTP versus SCP"

A while ago I failed a review audit because of the known problem that  and that the answer is not completely correct.   The failed review audit:  The inappropriate answer with my comment:    Could you please remove the answer from the audit pool if it does not get corrected?  Also please do something with the problem that . Such unjustly failed audits discourage reviewers from voluntary help to Stack Exchange.


Is “a choice between one of two options” grammatically correct?

In:     a choice between one of two options   I would like to know if this is correct grammatically. I came across it in a scientific paper. I think the “one of ” part should be removed. Am I correct?


So I want to write the following sentence about a future job that I would like to have but I don't know which preposition should I use.     I would like to work in/on/at something related to arts.


I have a little issue, my bibliography (using Biblatex, biber) is written in upper case while I did note specified anything (I think), and I'm not happy with this.  Here is a little example :  \documentclass[a4paper,10pt,twoside]{article} \usepackage[english,french]{babel} \usepackage{filecontents} \usepackage[     backend=biber,     style=chem-angew,     doi = false,     url = false,     sorting = none, ]{biblatex} \setlength\bibitemsep{0.8\itemsep} \renewcommand*{\bibfont}{\small} \begin{filecontents}{sample.bib} @article{myArticle, author={Author}, title={Title}, journal={Journal}, year={2000}, volume={1}} \end{filecontents} \addbibresource{sample.bib}  \begin{document} \begin{refsection}  Let's cite this : \cite{myArticle}.  \printbibliography \end{refsection} \end{document}   And I obtain "AUTHOR" with the A bigger than the other letters, but still everything in capitalized letters. I saw people have similar issue, but usually this is the opposite.


He became firm ‘friend’ or ‘friends’ with?

I was reading BBC culture page ( See  ). In the middle of the text, we see:  He became firm friends with the Shakespeare and Company owner in a relationship that lasted until his death 40 years later.  Q1: Does the writer make a mistake? Q2: Why has the writer used the plural form of "friend"?


I have recently purchased a hybrid bike with suspension (not sure if that is relevant to this question). It came with two pieces of plastic. Any ideas what they may be for?


I have a person table. I also have a car table and books table.  The car and book tables both have a foreign key back to person.  I am trying to count the number of books and cars each person has. I tried:  SELECT      Person.Name,      COUNT(BooK.bookid) books,      COUNT(Car.CarId) cars  FROM Person, Book, Car  WHERE Person.ID = Book.PersonID = Car.PersonID    but I get:  Incorrect syntax near '='


What is the formula for determining time dilation (as the object in motion)?

The formula for calculating how much time passes for a still observer is T=TO/(1-v^2/c^2)^1/2.  How do I calculate what TO is?


What hash is concatenating with the data to be signed in TLS 1.3 CertificateVerify message?

According to specification, to create data that will be signed with server private key for CertificateVerify message, we need to concatenate 64 space characters, the string "TLS 1.3, server CertificateVerify", null and the hash of all handshake messages to this point. During the handshake process, we choosing the cipher suite and signature scheme... So, if the cipher suite is, for example, TLS_AES_256_GCM_SHA384 and the signature scheme is rsa_pss_rsae_sha256 (different hash algorithms), hash of which algorithm should be used as handshake hash in data to sign, SHA-384 or SHA-256?


Impossible to boot or install from USB stick (Ubuntu 17.10 - ROG G20AJ)

I want to install Ubuntu 17.10 on my Asus ROG G20AJ computer, equipped with the Nvidia GTX 980 Ti GPU and Intel Core i5 CPU.  I've taken a USB drive with a live CD Ubuntu version (that I've already used to install Ubuntu with success on a laptop PC, also Nvidia, Intel, and Windows-powered), but I stick on the GRUB. I've disabled Secure Boot and Fast Boot. I enabled CSM and UEFI execution (my Windows system is installed with UEFI mode).  But by booting on the USB drive, I stick to the GRUB screen with any option (Install Ubuntu or Try Ubuntu without installing) broken. Indeed, when I boot in both options, I'm faced with these errors and the PC doesn't continue to boot:    I've also tried to add acpi=off nomodeset options to both boot commands. Instead of that error logs, the computer gets stuck on a black screen indefinitely.  How can I make Ubuntu installable on my computer via the USB stick, since the latter works on another computer before without any problems?


Could it be a structure of "How many -singular noun- is there?"

We had an argument in our collage if it's possible to have such structure:     "How many -singular noun- is there?"   For example:      How many chair is there?   The claim of the supporters: This structure should be used in case that t is not known whether there is one one or more chairs there. While just in case that it is known certainty that there are more than one chair, it should be "how many chairs are there".    The claim of the opponents: This structure cannot be since using the phrase "how many" always should be with a plural noun.  Both sides are not native English speakers, then I would like to know what is the truth.


Is it better to put hyphens in a domain name?

Both in terms of SEO and user friendliness, is it better to put hyphens in a multi-words domain name or not ?  For example, is www.stackoverflow.com better than www.stack-overflow.com ?


How energy is conserved in destructive interference of plane waves?

Let us consider two plane waves of same amplitude and frequency but having 180 degrees phase difference.Both the waves are having energy E in them which is directly proportional to the square of the amplitude.So the total energy is two times E.Now if both waves interfere,the amplitude of resulting wave is zero and the energy in the resulting wave is zero.What happend to the energy in both plane waves


What kind of checks and balances are in place for over-zealous, puritan moderators who seem to have nothing better to do with their time than make it very difficult for people with genuine questions to get answers? Case in point- I was working on an answer to  on GIS Stack Exchange, which I considered to be on-topic. The OP was asking a programming question related to prominent GIS software and features. Next thing I know, the question is put on hold as off-topic. Per the  page:      Keep the site reasonably on topic by closing, migrating, or removing   blatantly off-topic questions.   With as little reputation as I have, is there nothing I can do to help users like this escape the oppressiveness and get answers to their questions?


Improving Rigidbody collision between real-time movable object and other Rigidbodies

I have a cube that has been scaled to be rectangular (controlled by a remote Raspberry Pi gyro/accelerometer/magnetometer) and am translating its orientation into Unity via calls to transform.localEulerAngles = new Vector3(...). This works wonderfully (the cube object modeled to be a Pi rotates perfectly), however now I'm running into issues with the actual physics.        Initially the ball will land on and roll around the Pi object, however when I start to increase the speed of my movements the ball will sometimes fall through the Pi.  The cube has a Rigidbody (no gravity, is kinematic) and Box collider (not triggered), and the sphere has a Rigidbody (has gravity, not kinematic) and Sphere collider (not triggered) attached.  I've tried varying the collision detection from discrete to continuous on both objects and have noticed similar behaviors.  The intent is to turn this into a marble maze type game, and the issue that I have is similar.  If I roll the ball into the joint between a wall and the floor (both stretched cubes), rotate it down, and then rotate it up, the ball will fall through the joint.  I have the same movement code attached to the GameArea object below.  Again, same issue with various types of collision detection applied.       My assumption is that this is a quickness of movement thing, as the cubes overlap each other (there's not a space for the ball to sneak through).  For reference, in the physics colliders section of the project preferences, all relevant layers are supposed to collide with each other.  I don't mind getting into code-based collision detection, but this seemed fairly trivial for Unity to take care of so I was wondering if I was missing something obvious.


Prove that there exists a unique function $f: [0, \infty) \to [0, \infty)$ which satisfies the equation $f(f(x))=6x-f(x)$  $f(x)=2x$ seems to satisfy except $f(0)=0$ but $0$ is not in the codomain. Let $f(0)=a \implies f(a)=a$ which means there's a fixed point. Also, I can show that it's an injective function.


How to make String.Contains case insensitive?

How can I make the following case insensitive?  myString1.Contains("AbC")


Python why is 10e26 != 10**26 ? (Floating point inaccuracy?)

I was trying to process some rather large numbers in python and came across an overflow error. I decided to investigate a little bit more and came across an inequality I cannot explain. When I evaluate 10^26 I get:   >>> 10**26 100000000000000000000000000   Which is perfectly logical. However when I evaluate 10e26 and convert it to an int I get:  >>>int(10e26) 1000000000000000013287555072   Why is this? Do I not understand the e notation properly? (From what I know 10e26 is 10*10^26 as seen in this answer: )   10^26 is way past the max integer size so I was also wondering if there was any mechanism in python which could allow to work with numbers in scientific format (not considering all those zeros) in order to be able to compute operations with numbers past the max size.


I'm using Cox-Regression to analyse the risk of loan portfolios.   I found out that with increasing sample size, my regressors are getting more and more significant (p-values are shrinking) due to shrinking standard errors.  How valuable are these p-value statistics in the end? I'm concerned that these p-values are only "good" due to my large data set. Is there maybe like a limit of how big the data set should be?


What is the best option to save country wise state and city information? XML or database?

I'm creating a list of all countries and major cities in the world. The list has about 7000 nodes including countries, states and cities. It seems like this: United States - California - Los Angeles  And I need to search locations by keyword. I've created a XML file to store them, the file is about 300kb and average query time is 30-40ms. But now I need to search locations by multiple languages, so I must extend the file which is a problem. I like the convenience of reading XML directly but I need the extensibility of database. I wonder which one I should use to store data like these that don't change often but need to be queried?


I am developing a project, for which I want to scrape the contents of a website in the background and get some limited content from that scraped website. For example, in my page I have "userid" and "password" fields, by using those I will access my mail and scrape my inbox contents and display it in my page.  I done the above by using javascript alone. But when I click the sign in button the URL of my page () is changed to the URL (.) which I am scraped. But I scrap the details without changing my url.


Install MikTex shared for dual booting Linux/Windows

I have a dual booting machine, and I want to be able to work on my documents regardless of the OS I'm in.   I can easily install MikTex in both OS independently. However, I think is a waste of space to have a duplicate repository. Is there a way to install it in such a way that the DB or other components that are independent from the OS can be shared and updated accordingly?


How, if at all, does pure mathematics benefit from $2^{74207281}-1$ being prime?

So a couple of days ago the $17$ million digit number $2^{57885161}-1$ was beaten by the $22$ million digit number $2^{74207281}-1$ at being the largest known prime number.  Are there any specific (purely mathematical) implications of the fact that this particular number is prime? In particular, does this resolve something other than the question if $2^{74207281}-1$ is prime, in the style of some newly discovered theorem resolving previous conjectures? Is it perhaps a counterexample to something so far believed to be true?  Edit: I'm aware of the many non-(strictly mathematical) practical implications and reasons to continue the search for large primes (cryptography etc), but I'm not aware of any strictly mathematical uses of particular numbers being prime, which is why (and what) I'm asking.


I have downloaded a digital soil map of the world from:   It has lots of files in it with different endings (shp, sbx, xls etc.). I am using QGIS 3.4. When I add vector layer and add the shapefile, all it does is loads a bunch of polygons with no soil colour to differentiate them (they are all the same colour). When I try to load all the files in the zip file at once, the same thing happens.   Can anyone tell me what I am doing wrong?


When or where did "sth" come to mean "something"?

This is not the same question as  although one of it's answers is a partial answer to this question.  This question does not relate to "what does sth mean?" but those that it has that meaning for.  In  user @jon-hanna explains that the abbreviation originated in dictionaries, guides, and reference books, misleading readers into thinking that such abbreviations are standard use.  This answers one meaning of the where part of the question, leaving open the when which @jon-hanna has not addressed, and where this has been observed.    I'm a native speaker, born and living in england, and widely read from modern books and many classics.  I've seen sth as an abbreviation of something, but only informally from those who have learned English as a second language.  I've seen this from Chinese and also those from eastern Europe.  I the late 1990's I asked one user where he learned the term and he reported that his language teacher taught that abbreviation as being current in the English speaking world.  When I first saw this on a computer forum I had to ask what it meant, as the obvious sexually transmitted herpes (derived from STD) did not fit the context.  So the questions are:   where and when did this abbreviation originate? have you seen this used by native English speakers anywhere in the world? (particularly pre-internet age, ~1990)


Just wondering, is there a way to have a model change depending on the camera angle? For example, in front view, you can see Mickey Mouses ears typically on top his head. But on side view his years keep facing the camera as they would from the front view. Not sure if I'm asking the right question, but is there a way to have that Mickey Mouse ears effect thing depending on the angle? And also, is there a way to have the front and side view models to change seamlessly?


How to set custom keyboard shortcuts from terminal?

How to set custom keyboard shortcuts from terminal for different Linux versions?  Basically I want to know where Linux stores the keyboard shortcut files and how it can be edited.  On my research I found a file ~/.config/compiz-1/compizconfig but it was more or like encrypted when I tried to open it with nano.


SanDisk 16GB SD memory card is suddenly unreadable on my phone and computer

I have a 16GB SanDisk SD memory card that suddenly started showing this message to me on my phone:  “UNSUPPORTED SANDISK SD CARD”  And says:  “This device doesn't support this SanDisk”  It then takes me to the formatting and erase option. I tried connecting the card to my computer with card reader but it is not showing up in “My Computer.” However the sound does come when I connect but the card is not shown. I did a virus scan just to be sure of my computer while it is fixed, its clean. I need the files in the card.


suid bit in SuSE has no effect through system()

[EDIT: Revisiting this question and seeing it is still wrongly marked as a duplicate] The following question on SE is not a duplicate as it asks about executing bash with the suid bit, which is a special case and does not work at all:  The first difference is that in my example I execute whoami, not bash. The second difference is that it actually works as expected on Ubuntu, but not on SuSE.  Suid bit works fine on my PC running Ubuntu, but not on a SLES test instance. The nosuid flag is not set on the mounted xfs file system on the SLES machine. ls shows that ony my machine and the SLE Server, the same permissions are set for the executable. So why does the executable still run as the current user instead of as the owner?  execsudo.c:  #include <stdio.h> #include <stdlib.h>  int main(int argc,char *argv[]) {     system(argv[1]);     return 0; }   bash:  gcc -o setuid-test execsudo.c ; sudo chown nobody ./setuid-test; sudo chmod +s ./setuid-test; ./setuid-test "whoami"  # Outputs current user instead of nobody   [EDIT 2]  I still have not worked out the problem, but I suppose it might be because the SuSE machine is a VM. A workaround might be to configure this behaviour via /etc/sudoers instead.


Showing that $f_n$ is the number closest to $\frac{1}{\sqrt{5}}(\frac{1+\sqrt{5}}{2})^n$

I want to prove that the the $n$th Fibonacci number $f_n$ is the integer closest to $\frac{1}{\sqrt{5}}(\frac{1+\sqrt{5}}{2})^n$. What would be a rigorous way to go about this? I assume I'll have to use a recurrence relation and maybe Binet's Forumla. I just don't know how to go about tying it all together, so any advice on how to proceed would be much appreciated.


Is $a \le b$ a true statement if $a < b$?

My question is:  Is $a \le b$ true if $a < b$?   For instance: Is $3 \le 4$ a true statement? I think yes, because $a \le b$ is defined as $a < b\vee a = b$ and this should be true, even if $a = b$ is always false, right?  Thank you very much for your help! FunkyPeanut


In The Last Jedi, the resistance fleet, seemingly about to be destroyed, fortuitously comes across the planet Crait, and Leia "reveals" a plan to stealth down to the planet to escape.  This is news to the audience, who thus far knew that Admiral Holdo's plan was... to just keep running until they died?   ...or was it?  Did Vice Admiral Holdo know about the presence of Crait and/or intend to go there all along?  Answers directly from the movie are preferable, but other canon material is also acceptable.  Incidentally, if she did know about Crait, why was this information not shared with the rest of the resistance command?  Corollary question discussed , though I would prefer an explanation from canon material instead of speculation.


Let's say I have a bunch of points:    What is the best way to get a certain amount of closest neighbors. For example I wan't the 8 closest points for point no 57.  This without using brute force.  O yeah, if possible, it would be great if it's efficient for moving points as well.


It seems that the top half of my mesh might be inverted somehow. It has a weird shadow on it. Not sure what this problem is called. I'm new to Blender. Any advice on how to fix this?


Will time exist in heat of the universe?

Will there be any sense of time during the heat death of universe? Since there is no interesting events I think you cannot measure time.


expected area of a triangle determined by randomly placed points

Three points are placed at independently and at random in a unit square. What is the expected value of the area of the triangle formed by the three points?


Coin tossing game with one yes/no question.

Let's assume we are playing a game. You have $100$ coins, you toss them and do not tell me the results. I can ask one yes/no question and after your answer I'll start guessing the coin results. For each correct result I'll get $1$ dollar and for each wrong guess I'll lose $1$ dollar. What is the best strategy for me to play the game? What is the average income of the strategy?   Edit: Here is a strategy with higher than $1$ dollar return. Ask whether number of heads are greater than or equal to tails. If the answer is yes guess all them to be heads otherwise guess all of them to be tails.


Need a regex to capture numbered citations

Bit of a regex newbie... sorry. I have a document with IEEE style citations, or numbers in brackets. They can be one number, as in [23], or several, as in [5, 7, 14], or a range, as in [12-15].   What I have now is [\[|\s|-]([0-9]{1,3})[\]|,|-].  This is capturing single numbers, and the first number in a group, but not subsequent numbers or either number in a range.  Then I need to refer to that number in an expression like \1.  I hope this is clear! I have a suspicion I don't understand the OR operator.


how long does the cycle length have to be in stream ciphers?

could someone tell me how long the cycle length must be in stream ciphers, so a security exists. how to compare the cycle length to the state space?  I investigate the algorithm spritz and I have the attainability of the states under investigation with key lengths of 1 - 10 and n = 6. now I have the values but I still do not know how to interpret them. the maximum cycle length for N = 6 is 660.390 and the smallest 12. But how should I evaluate this with regard to the safety? I hope I have described it somewhat better.


MySQL Access denied for user 'root'@'localhost'

In my server, everytime I try to access MySQL I get the error:        Access denied for user 'root'@'localhost' (using password: NO)   when I try mysqladmin -u root -p password I get        Access denied for user 'root'@'localhost' (using password: YES)   How can I access MySQL in my Ubuntu server 12.04?


I am writing a chess game using Java and Swing, And I wanted to get the tile position on which a mouse clicked. I searched through internet, but all of them were really off, and never accurate. When I clicked on a tile's first half, it said it was tile 1, but on the second half, it said it was tile 2, but it was still tile 1. So I was wondering, how can I do it? My tile size is (75, 75) This is the code I've written for tileX: Math.floor((double)evt.getX() / 75), and this is the code I've written for tileY: Math.floor((double)evt.getY() / 75). Code for drawing: ImageIcon l_winter = new ImageIcon("/Users/user/NetBeansProjects/chess/src/b/bibe/assets/winter/light.gif");         ImageIcon d_winter = new ImageIcon("/Users/user/NetBeansProjects/chess/src/b/bibe/assets/winter/dark.gif");         ImageIcon l_wood = new ImageIcon("/Users/user/NetBeansProjects/chess/src/b/bibe/assets/wood/light.png");         ImageIcon d_wood = new ImageIcon("/Users/user/NetBeansProjects/chess/src/b/bibe/assets/wood/dark.png");         String theme = th;         int color = 0;         for (int i = 0; i < 600; i = i + 75) {             for (int j = 0; j < 600; j = j + 75) {                 JLabel panel = new JLabel();                 panel.setText(null);                 panel.setSize(75, 75);                 if (color == 0) {                     if (theme.equals("wood")) {                         panel.setIcon(l_wood);                     } else if (theme.equals("winter")) {                         panel.setIcon(l_winter);                     } else {                         panel.setText("notexture");                     }                     //panel.setBackground(new Color(white[0], white[1], white[2]));                     color = 1;                 } else {                     if (theme.equals("wood")) {                         panel.setIcon(d_wood);                     } else if (theme.equals("winter")) {                         panel.setIcon(d_winter);                     } else {                         panel.setText("notexture");                     }                     //panel.setBackground(new Color(black[0], black[1], black[2]));                     color = 0;                 }                 panel.setLocation(j, i);                 getContentPane().add(panel);             }         if (color == 0) {             color = 1;         } else {                color = 0;             }         }


How can I turn off the fullscreen setting if I can't access the menu?

I turned on fullscreen but Minecraft crashed and now it crashes every time I start it. Please tell me how to turn fullscreen off if I can't access the settings menu.


I can't get the BibLaTeX Package to work. When I run the 'create bibiliography'-command from TextMate I get the following error Message  INFO - This is Biber 1.9 Command bibtex exited with status 2   The Produced PDF-Document contains only  [wikipedia ]   but no bibliography.  The log of the pdftex doesn't show any useful information on this error  Document Class: scrbook 2015/02/07 v3.16 KOMA-Script document class (book)  LaTeX Warning: Citation 'wikipedia' on page 1 undefined on input line 8. LaTeX Warning: Empty bibliography on input line 9. LaTeX Warning: There were undefined references.  Output written on Minimalbeispiel.pdf (1 page, 18613 bytes).   a Minimalexample which produces this error is  \documentclass{scrbook} \usepackage{biblatex} \addbibresource{library.bib}  \begin{document}  \cite{wikipedia} \printbibliography  \end{document}   and the library.bib-Entry is  @misc{wikipedia,     Author = {Wikipedia},     Note = {[Online; accessed 24-March-2015]},     Title = {Porosity --- Wikipedia{,} The Free Encyclopedia},     Url = {http://en.wikipedia.org/w/index.php?title=Porosity&oldid=651280533},     Year = {2015},     Bdsk-Url-1 = {http://en.wikipedia.org/w/index.php?title=Porosity&oldid=651280533} }   I have already used several hours searing the Web for help but couldn't find anything helpful.  I'm using TextMate version 2.0-beta.6.8 and the MacTeX-2014 Bundle  Greetings and thanks for any Help


Why did the most important lords want this character freed?

In the season 8 episode finale of Game of Thrones the highest important lords met with Grey Worm to free      Tyrion and Jon. While it was pretty clear why they wanted to free Jon it was unclear to me why they also asked for Tyrion.   To make things even more strange, they asked about his opinion of a potential solution which becomes the actual final one in the end      (choose king and nominate someone).   I thought they (besides Sansa and Bran) don't like him and wanted to judge him? Or am I missing something?


If $\left|z^3 + {1 \over z^3}\right| \le 2$ then $\left|z + {1 \over z}\right| \le 2$

$\displaystyle \left|z^3 + {1 \over z^3}\right| \le 2$ prove that $\displaystyle \left|z + {1 \over z}\right| \le 2$     $$\left|z^3 + {1 \over z^3}\right| = \left(z^3 + {1 \over z^3}\right)\left(\overline z^3 + {1 \over \overline{z}^3}\right) = \left(z + {1\over z}\right)\left(z^2 - 1 + {1\over z^2} \right)\left(\overline z + {1\over \overline z}\right)\left(\overline z^2 - 1 + {1\over\overline z^2} \right)$$  $$=\left|z + {1\over z}\right|^2\left|z^2 - 1 + {1\over z^2} \right|^2 \le 2$$  $$\therefore \left|z + {1\over z}\right| \le \sqrt{2}$$ where $\displaystyle \left|z^2 - 1 + {1\over z^2} \right| \ge 1$.     But I am not able to prove $\displaystyle \left|z^2 - 1 + {1\over z^2} \right| \ge 1$, need some help on this.


I am using ubuntu 14.04 system. Please anyone can tell me how to set static IP address on my system.


Is it possible to add to this render data?

I'm making an addon as a personal project and it estimates the total render time left for an animation render. i want to show how much time is left to the user. but a pop-up wont work and crash blender. is there a way to show data here? if not, is there another way to show this data?


I have problems proving the following result:     Each $f: \mathbb{R}^2 \rightarrow \mathbb{R}$ such that $\forall a,b \in \mathbb{R} \ : \ f_a(y) := f(a,y), \ f_b(x) := f(x,b) $ are polynomials is a polynomial with two variables.   If I consider $f$ as a function of $x$, then its derivative  $f'(x) = \frac{\partial f}{\partial b}(x)$. Similarly if we treat $f$ as a function of $y$.   I assume that $f_a(y) = \frac{\partial f}{\partial a} (y) $ and $f_b(x)=\frac{\partial f}{\partial b}(x)$.  But I am not sure if we can assume that, because  the degree of the derivative should be smaller than the degree of the original function (and it isn't).   Actually, I'm not even sure if what I'm trying to prove is true, because in the original formulation of the problems there is written $f_a(y) := (a,y), \ f_b(x):=(x,b)$. But that didn't make sense.  Could you help me here?  Thank you.


I'm reading the proof of the multiplicative property of $$s_k(n)=\sum_{d|(n,k)}f(d)g\bigg( \frac kd\bigg)$$ The book wrote that in order to understand the proof, we need to know if $a,b,k,m$ are integers such that $(a,k)=(b,m)=1$, then $$(ab,km)=(a,m)(b,k).$$  I have written proof, but I don't know is it consistent, and this seems used more tools than it necessarily has to.   My proof: Let $$S_1=\{d: d|(a,m), d>0\}\\S_2=\{d: d|(b,k), d>0\}\\S=\{d:d|(ab,km), d>0\}.$$ I will prove the statement by showing that the function $\phi:S_1\times S_2\to S$ defined as $$\phi(d_1,d_2)=d_1d_2$$ is bijective, and complete the proof by connecting the maximal elements from these partial ordering sets.  Obviously, for $d_1\in S_1, d_2\in S_2$, this tells us $d_1 $ is both divisor of $a$ and $m$, and $d_2$ is both divisor of $b$ and $k$, hence $d_1d_2$ is both divisor of $ab$ and $km$, so we can tell $\phi(S_1\times S_2)\subseteq S$.  To show one-to-one, if we have $c_1,d_1\in S_1$ and $c_2,d_2\in S_2$ such that $$\phi(c_1,c_2)=\phi(d_1,d_2)$$ then $$c_1c_2=d_1d_2$$  In particular, $c_1|d_1d_2$, we need to show $c_1|d_1$. Indeed, if $(c_1,d_2)>1$, this implies $a,k$ have common factor larger than $1$, contradicts the assumption. Therefore $c_1|d_1$. A similar argument implies $d_1|c_1$, therefore $c_1=d_1$. Again a similar argument implies $c_2=d_2$, which shows one-to-one.   To show onto, let $d\in S$, since $d|ab$, we can split $d$ into $d_1d_2$ such that $d_1|a$ and $d_2|b$. Since $(a,k)=1$, we see $(d_1,k)=1$, by property of $S$ we see also $d_1|m$, therefore $d_1\in S_1$, a similar argument implies $d_2\in S_2$. So every number in $S$ has a preimage in $S_1\times S_2$  This completes the proof. Is there any mistake in the proof?     Edit: A proof about the statement: If $d|ab$ then there are $d_1,d_2$ such that $d=d_1d_2$ and $d_1|a, d_2|b$.  Let $ab=p_1^{e_1}\cdots p_r^{e_r}$ for distinct prime factors $p_1,\cdots,p_r$, then we can write $$a=p_1^{x_1}\cdots p_r^{x_r}\\b=p_1^{y_1}\cdots p_r^{y_r}$$ where some of $x_i, y_i$ can be zero, and $x_i+y_i=e_i$ for all $i=1,\cdots,r$.  Since $d|ab$, we can write $$d=p_1^{f_1}\cdots p_r^{f_r}$$ with $f_i\leq e_i$ for all $i=1,\cdots,r$. Then since $$f_i\leq x_i+y_i$$ Split into two cases:   Case 1: $f_i> x_i$, then we can choose $g_i=x_i$ and $h_i=f_i-x_i$.  Case 2: $f_i\leq x_i$, then we can choose $g_i=f_i$ and $h_i=0$.  Then the choice $$d_1=\prod_{i=1}^r p_i^{g_i}, \quad d_2=\prod_{i=1}^r p_i^{h_i}$$ will prove the statement.


Is it always best practice to not include text punctuation in inline math mode?

It has been pointed out on this site, e.g. , that text punctuation doesn't belong to the formula in inline math. I've been following this practice for a long time, so I write for all $v\in V$, where ... as opposed to for all $v\in V,$ where .... However, the first version prevents kerning between V and the comma. Note that the comma is a lot closer to the V in the second version:    \documentclass{article} \begin{document} $v\in V$, where \quad $v\in V,$ where  \end{document}   Note that there's no difference between the two versions if I replace V with A:    Now I'm wondering: Should I start including punctuation in my formulas to enable proper kerning, at least as long as fonts are used where the text and math punctuation glyphs look the same? Or are there reasons why the kerning is not desirable anyway?


how is current measured through ammeter?

If we join a shunt through a galvanometer,it makes an ammeter.but in parallel arrangement voltage is same and only some amount of current is passed and not the total current of circuit.so how does the ammeter gives the value of total current in circuit????


Cancelled Summer Program due to COVID-19

I am sure this question has been asked in some capacity on this site. I am a first year graduate student. I was contracted for a summer program that would have looked very good on my CV about 6 weeks ago.   However, due to the spread of COVID-19 the program was cancelled. Is there any way I can express this on my CV (possibly have an asterisk next to this activity)? If not, how should I explain the situation when applying for positions next year (because, now it is unlikely I will have anything noteworthy to put on my CV for this summer).  Thank you


Very slow disk performance on Dell PowerEdge 2950 w/ PERC 6/i running RAID 10

I recently set up a server running Ubuntu 10.04 LTS on a Dell PowerEdge 2950 server - it has 6 500 gb 7200RPM SATA drives setup in a RAID 10 config.  I am seeing extremely poor disk performance - the RAID array reports all disks are normal and using MegaCLI, it looks like the BBU is fine.    hdparm -tT /dev/sda reports:   Timing cached reads:    90 MB in  2.05 seconds =  43.96 MB/sec Timing buffered disk reads:   24 MB in  3.11 seconds =   7.72 MB/sec   So as you can see, it takes forever to something as simple as an apt-get upgrade and even logging into the server.    How do I go about troubleshooting what is causing this?  I upgraded the firmware on the PERC 6i RAID controller to the latest, but didn't see any improvements.


I'm trying to log-in to my tablet, which I haven't been on in about 2 months. I can't remember my PIN. It's not giving me a chance to log-in with my Google account, so I don't know what to do.


Looking for a post-apocalyptic trilogy where pilot is nursed back to health by natives of the land

I read a series of books around 2005. I think it might have been a trilogy.  Basic story line is in a post apocalyptic world. The main character is a pilot for the Federation or something similar to that. He crash lands, is nursed back to health by the natives, comes to like and respect them, and does not want to fight against them.  Also in the later book I think it also involves another race who are very Japanese-ish. They drink sake and the "clan" names are things like Fu-Jitsu and Mitsu-Bishi.


I have a problem with sendmail.  All of the sudden it started sending emails that its not supposed to send (obviaou spam messages about viagra, porn etc.). I checked some tools that supposedly check if server is an open relay and they say its not, but here is the excerpt of mail.log  Jul  6 18:13:23 onejob sendmail[30792]: t66IDN9E030792: Authentication-Warning: onejob.com: www-data set sender to mari_gill@onejob.com using -f Jul  6 18:13:23 onejob sendmail[30792]: t66IDN9E030792: from=mari_gill@onejob.com, size=480, class=0, nrcpts=1, msgid=<201507061813.t66IDN9E030792@onejob.com>, relay=www-data@localhost Jul  6 18:13:23 onejob sm-mta[30780]: STARTTLS=client, relay=mailin-01.mx.aol.com., version=TLSv1/SSLv3, verify=FAIL, cipher=DHE-RSA-AES256-SHA, bits=256/256 Jul  6 18:13:23 onejob sm-mta[30793]: t66IDN56030793: from=<mari_gill@onejob.com>, size=790, class=0, nrcpts=1, msgid=<201507061813.t66IDN9E030792@onejob.com>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jul  6 18:13:23 onejob sendmail[30792]: t66IDN9E030792: to=twistedkush24@aim.com, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30480, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (t66IDN56030793 Message accepted for delivery)   How do I figure out what causes sendmail to send all those emails?


How to deal with variables that are follow ups of prior questions when using panel data?

I have a panel data set where one of the variables is employment status is where 1= employed and 0 = not employed. The other variables are for those who have employ=1, such as place of employment, sector, number of hours worked etc.   I would like to run a fixed-effects model where I have the variables above as independent variables. However, those who have employ=0 have missing values for the workplace, sector , number of hours etc.    Under crossectional data, I would have made a subset of employed individuals and just analysed that but I don't know how to deal with this issue in panel data.


I want to install Ubuntu 12.04.03 onto my HP laptop along side Windows ( Dual Boot ) Under the "God Mode" for Windows 8, I have a partition utility - 500GB Free on the system drive, what is recommended for Ubuntu?  Also, driver compatibility - AMD A8 - APU 1.9Ghz quad core, Radeon 7640G Video,  AMD High Def Audio, with IDT High Def Codec. Qualcomm Atheros WiFi Realtek PCIe FE Family Controller  Are there any know issues with any drivers or dual OS with Win 8.1?


Not so much as [something] as [something else]

Consider the sentence:     "She sees him not so much as her uncle as her friend."   Is this sentence correct? I feel something is missing, or perhaps I am disturbed by the extra 'as'. Compare with:     "He is not so much her friend as (he is) her uncle."   What do you suggest?


Loading relations in linq2entities automatically

When i have a relation between two entities in my model:  [GroupMember] (*) ----- (1) [User]  and tries to select items from this relation with LINQ:  From entity in _user.GroupMember select entity  I always get an empty result unless I load the relation first with following statement:  _user.GroupMember.Load()  Is there a way to avoid loading the relations like this?


I am able to see logged-in users via the who or last command.  How can I log off a particular user who login through SSH?


Are roots of $\det(A-tB)$ with symmetric matrices real?

Let $A$, $B$ be symmetric real matrices $n \times n$-type. Let's consider the polynomial $$ f(t)=\det(A-tB). $$  If $B$ is positive definite, then it is known that $f$ has only real roots. Is the same true for nonsingular $B$ (and $A$, $B$ symmetric)?


unable to retrieve data of a single row using room database

Unable to get particular record from database getting this output.  My output is :      java.lang.RuntimeException: Unable to start activity ComponentInfo{appwork.com.example/appwork.com.example.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.arch.lifecycle.LiveData.observe(android.arch.lifecycle.LifecycleOwner, android.arch.lifecycle.Observer)' on a null object reference   I am using room database, Modelview, Repository and Dao file to get Live data but unable to get particular record from database via following things      <pre><code>     public class MainActivity extends AppCompatActivity {          private NoteViewModel noteViewModel;          @Override         protected void onCreate(Bundle savedInstanceState)         {             super.onCreate(savedInstanceState);             setContentView(R.layout.activity_main);              noteViewModel =      ViewModelProviders.of(this).get(NoteViewModel.class);             noteViewModel.getNote("test7").observe(this, new Observer<Note>()             {                    @Override                    public void onChanged(@Nullable Note note)                    {                        Toast.makeText(MainActivity.this,                             "found title is : " +note.getTitle(),                             Toast.LENGTH_LONG).show();                    }                  });             }         }         public class NoteViewModel extends AndroidViewModel     {         private LiveData<Note> note;          public NoteViewModel(@NonNull Application application)         {             super(application);     //        note = repository.getNote("");         }          public LiveData<Note> getNote(String search)         {             repository.getNote(search);             if(note != null)             {                 return note;             }             return null;         }     }       public class NoteRepository {          private NoteDao noteDao;         private LiveData<Note> note;          public NoteRepository(Application application)         {             NoteDatabase noteDatabase =      NoteDatabase.getInstance(application);             noteDao = noteDatabase.noteDao();         }          public LiveData<Note> getNote(String search)         {             new SearchNoteAsyncTask(noteDao).execute(search);             if(note != null)             {                 return note;             }             return null;         }          public static void asyncFinished(LiveData<Note> results)        {             note = results;        }          public static class SearchNoteAsyncTask extends AsyncTask<String, Void, LiveData<Note>>         {             private NoteDao noteDao;             private LiveData<Note> note;              private SearchNoteAsyncTask(NoteDao noteDao)             {                 this.noteDao = noteDao;             }               public LiveData<Note> doInBackground(String... search)             {                 return noteDao.getNote(search[0]);             }              public void onPostExecute(LiveData<Note> result)             {                 asyncFinished(result);                         }         }     }      @Dao     public interface NoteDao{     @Query("Select * from note_table where title =:search Order By priority DESC")         LiveData<Note> getNote(String search);     }   I am getting response in Repository call but unable to get value from public   static class SearchNoteAsyncTask extends AsyncTask<String, Void, LiveData<Note>>   Any working example will be great!  thanks


To close laptop lid without doing anything

how to close my laptop lid in ubuntu 18.04.2 without doing anything? i tried sudoedit /etc/systemd/logind.conf and also sudoedit /etc/UPower/UPower.conf


wifi is very poor and unstable --> after installing ubuntu mate 16.04 in HP Pavilion 15-ab032tx Notebook

I have installed ubuntu mate 16.04 in my HP Pavilion 15-ab032tx Notebook. (windows 8.1 is also there though i have dual booted). I have updated and upgraded by: sudo apt-get update sudo apt-get upgrade - in terminal then I found wifi signals shows very poor and often disconnects. But when i log into 'Windows' wifi gets full signal strength and stable. then I searched lot for solution I tried:    and many more methods but still no solution I am new to ubuntu.. help me to fix this please. thanks.. some informations that may require for solution are below: hardware info: after typing sudo lshw in terminal  `my pc                           description: Notebook     product: HP Pavilion Notebook     vendor: Hewlett-Packard     version: Type1ProductConfigId     serial: ###     width: 64 bits     capabilities: smbios-2.8 dmi-2.8 vsyscall32     configuration: administrator_password=disabled boot=normal chassis=notebook family=103C_5335KV G=N L=CON B=HP S=PAV X=Null sku=### uuid=###                     *-network                 description: Wireless interface                 product: RTL8723BE PCIe Wireless Network Adapter                 vendor: Realtek Semiconductor Co., Ltd.                 physical id: 0                 bus info: pci@0000:08:00.0                 logical name: wlo1                 version: 00                 serial: d8:5d:e2:62:c4:65                 width: 64 bits                 clock: 33MHz                 capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless                 configuration: broadcast=yes driver=rtl8723be driverversion=4.4.0-28-generic firmware=N/A ip=192.168.0.100 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn                 resources: irq:18 ioport:5000(size=256) memory:c6100000-c6103fff   ` andproduct info:   I am extremely very sorry for the long post please help me to fix this problem. Thanks in advance...


Ubuntu with full disk encryption - bad password after upgrade to 18.04

A few months ago I set full disk encryption during installation of Ubuntu 17.10. Now, I've decided to upgrade. The upgrade ran to the end without any problems. However, after reboot I am not able to log into my encrypted disk.  Where can be the problem? I am 100% sure I press the "right keys" on the keyboard, but technically I don't know what I am writing because of "*" characters and maybe after upgrade my keyboard layout changed. I use some characters which might be somewhere else on the keyboard. What language is default after upgrade?   By the way, I've already tried Caps-lock, but still no luck.  Help will be really appreciated. I am not a fan of installing my system and all backups over and over again.


Does it make sense to get a PhD if a person does not want to be in academia and prefers to stay in business?

I am working in a highly technical field (quantitative finance/ statistical analysis) for a private company with a Master of Science degree in economics.   Does it make sense to get a PhD (in quantitative finance, math, statistics) if I do not want to be in academia and prefer to stay in business.    What I expect from PhD:    Structure and deepen my knowledge in the relevant fields through high quality classes (where I sit and listen and learn and do homework to make sure that I have learned). Get the ability to read any scientific article in the related fields and without much pain understand 90% of it to the very last detail (and implement ideas from the article in my work). Possibly acquire certain thinking and problem solving culture (so vague... and I guess after my Master I have a fair part of it already(?))      Also important:   PhD was never mentioned as a prerequisite for a promotion or a salary increase.  My colleges who have PhD are not visibly advantaged by the company (do not know about the rest of the industry, but the company being a big player is representative of it). I enjoy learning new stuff on my own (not a problem to spend many nights with a math book), but hate the status of a student (little money, slave of professors and their peculiar exam requirements).    So should I go for a PhD or rather a specialized Master, or develop myself through separate university courses of my choice and professional programs + self-study?   Any pieces of advice from people used to be in my situation?


Using wpdb to connect to a separate database

I want to connect wpdb to another database. How do I create the instance and pass it the database name/username/password?  Thanks


I want to learn a real microcontroller with STM32F4. Which library should I use (HAL, SPL, or CMSIS)?

From what I know, ST will stop to develop Standard Peripheral Libraries (SPL) for the next generations of STM32. And HAL is not ideal for people who want to understand well about STM32 and microcontrollers. Can you suggest me which one is the best to use (for learning and working in the future)?


How can I distribute a native executable for a Python program?

Lately all of my work has been in Python (and Ruby), and I'm in love with those two languages. There are many libraries for game development on Python but the problem I see is that many of those frameworks don't cover the "distribution" aspect of game creation. I'd like to code my game on Python (and any other pure Python extra libraries I need) and be able to distribute an executable for the main PC platforms (Windows, Mac and Linux).  Any options out there or what are the best combinations for this? (maybe pyglet + cx_freeze)


problems with downloading Winehq on Ubuntu 16.04

I was following the instructions on the  for winehq installation. When I executed   sudo apt-add-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ xenial main'   a blank line appeared with no response and it brought me back to the input line. I thought maybe it worked and then I executed sudo apt update and it said   Malformed entry 6 in list file /etc/apt/sources.list (component).    Can anyone help?   deb-src https://archive.Ubuntu.com/Ubuntu   xenial-security main restricted universe multiverse   Also if I may add I am running a chroot


Include protection/unprotection actions in profile's activity or votes tab

Having a record of all actions taken on a site, as is provided by the "activity" and "votes" tabs of our profile, comes in handy very often. Perhaps the most common case is being able to find a question I've interacted with in the past, to see if anything has changed about it. This applies to questions a user has protected as much as anything else. Users are theoretically encouraged to unprotect questions when it's no longer necessary, as emphasized , but in practice they often do not. In many cases it's hard to blame them: unless they specifically marked it as a favourite, the site doesn't keep any record of the question to allow them to find it again. We should help users more easily review their own protections in the future.    For personal review, the votes tab is adequate, but there may also be value in displaying this publicly in the activity tab. In the past I have specficailly noticed users with a history of repeatedly protecting questions over-egearly. It would be useful to be able to review other users' protection histories to see if this is the case. Even if this is not available to regular users, it may be helpful to moderators, unless their user activity views already allow them to filter down to see this.


How to import Sybase .db file into SQL Server database?

I've been given a Sybase .db file by a client and I need to import that into a new SQL Server database so that I may see the data as well as the tables and their relationships, any ideas on how that might be done shall be really appreciated :)


I just built a new PC, and I'm looking to dual boot Windows and Ubuntu. I have a 256gb SSD, which I would rather be dedicated to Windows. I also have a 2tb hard drive, which is where I'd like to put Ubuntu. I'd like Ubuntu to take about 256gb on the HDD, with about 1.75tb of shared storage for both Ubuntu and Windows. How would I go about doing this?


Plotting a 3d surface in tikz, with a limit to the infinity

I want to plot the function 1/(x²+y²), but since it tends to infinity in (0,0), I get a horrible plot:  \documentclass{article} \usepackage{tikz} \usepackage{pgfplots} \begin{document} \begin{tikzpicture}   \begin{axis}[grid=both]     \addplot3 [surf] {1 / (x^2 + y^2)};   \end{axis} \end{tikzpicture} \end{document}     By restricting the domain of z, I get anyway a not so nice plot:  \documentclass{article} \usepackage{tikz} \usepackage{pgfplots} \begin{document} \begin{tikzpicture}   \begin{axis}[grid=both,restrict z to domain=0:1]     \addplot3 [surf] {1 / (x^2 + y^2)};   \end{axis} \end{tikzpicture} \end{document}     I would like to get something smooth, which finish in a circle (the circle of the intersection of this function with the plane z=1 for example).  Something like this would be great:


A signal from a measurement is filtered with an analog 2nd order low pass filter. The original signal which consists of the sum of two exponentials (one positive amplitude the other one negative amplitude) slightly changes its shape. Since the information of important parameters can only be extracted from the unfiltered signal, I would like to undo the filtering digitally. I am aware that it is not possible to obtain the full original bandwidth, but could I theoretically increase the bandwidth? The filter's transfer function numerator is 1 while the denominator is a 2nd order polynomial.  Added:  My goal is to determine the values of an RC low pass (life science application). A voltage pulse is applied to the low pass filter. The arising current (which is a mono-exponential and contains the information of the R,C values in its time constant) is converted to a voltage (with an I-V-converter). The signal is then low-pass-filtered with a 2nd order Bessel filter. The sampling rate of the system is 20 kHz while the cutoff frequency of the filter is 3 kHz. Fitting algorithms are used to cancel noise in the output. My goal is to obtain the mono-exponential for any output signal.   Added: This is the actual circuit I wish to analyze.   I would like to obtain the current input at the ampere-meter for any output voltage. Of course in this simulation there is no noise. Before I apply the method to the real system I would like to make it work for the simulation. I've been using the MATLAB system identification toolbox in order to estimate the transfer function. By applying the inverse transfer function to the output I should be able to recover the original current input.


How can I set the defaults for pictures in my document?

I was wandering if there is a command that will let you define the size of graphics globally throughout then entire document. Most of my images are photos and should all be the same size and it would be good if I could change one thing that will affect the size of them all, rather than having to do it manually. For the odd picture here and there that has different dimensions I can adjust their size manually.  Question content copied with permission from .


I’m going to Queenstown, NZ in a couple of weeks and want to take my (very new, very precious) Canon 7D with me. I’ve done a little bit of research on how to protect my baby from cold climate (e.g. ) and found that the biggest problem is probably going to be condensation. Some suggestions have been to place the camera in a plastic bag or letting the camera gradually adjust to the new temperature or placing silica gel in the camera bag to absorb moisture. I am leaning toward the latter at the moment because it sounds like it’s the easiest, so I was just wondering if anyone has had any experience in this matter and could share their wisdom.  As an alternative I could take my Canon 350D, as I really wouldn’t care if that got damaged in the snow. However I’m a film student and tend to take just as many videos as photos – hence why I really want to take the 7D. But I would seriously regret it if it got damaged… dilemma!   So as I actually haven’t used a question mark in the body of text, I will specify that the question is: What safety precautions should I take when taking photos in the snow?  Cheers.


I moved a minimal background I had to another layer, then decided to just delete it and remake it on that layer, better than before. I made a nice background, and then I went to test it out, and moved it back to render it, and it showed the same everything I had last time! Nothing I had deleted or added was changed! I added and deleted a few things to test it out, and the render stayed the same, no matter where I moved the camera, or moved on the timeline.  I have no idea what to do! I saw a bunch of people say "Maybe you used H to hide it instead of deleting it." I tried the solution and it didn't work. I've been using X to delete everything.


How to travel x (e.g. 10) miles and get new co-ordinate having direction towards another location?

I'm trying to create a large but optimal circle that covers two intersecting circles. For that, I need to calculate new radius and new center point. I'm able to get the optimum radius by how can I get the new center point coordinate? I think we need to travel some X miles from one point to another. I have the calculation for X miles, but how to get the coordinate? See below illustration. I have points A and B as geo coordinates. I wanted to travel x miles (let's say 10 miles) from Point A to Point B and get the co-ordinate of point P. We can easily get the midpoint coordinates by (x1 + x2) / 2 formula which is 50% traveled from A to B but what if I want to travel 10% from point A towards point B?


SOQL Like operator with %%% returns all records of given object

If i run below query it returns all records of that object:  Select ID, name from Contact where Name like '%%%'   This should return only those records which have % in the name. For example if i run below query it will return only those records which have test in the name.  Select ID, name from Contact where Name like '%test%'   Any idea, What is going on here?


How can a black hole grow, as seen by an outside observer?

How can a black hole grow in mass, if it takes an infinite time to cross the event horizon,  for matter approaching the black hole (as seen from an outside observer far from the black hole)?  To make a black hole, one must concentrate mass or energy sufficiently that the escape velocity from the region in which it is concentrated exceeds the speed of light.  So , as seen from an outside observer, we have redshift and time dilation (all the GR effects in action ) for matter approaching the event horizon of a black hole.   Eventually (in finite time ),  the outside observer sees sufficient matter (energy ) accumulating in a small neighborhood of the event horizon of the original  black hole that other  black holes must emerge (in the neighborhood of the event horizon of the original black hole ). So the outside observer sees a continuous merging of black holes , those formed in the neighborhood of the event horizon of the original black hole, and the original black hole itself. That could explain how a black hole can grow, even as seen from an outside observer.   Question.  Is this explanation correct?


How to compare the user input that's a string with an integer?

So I want to ask the user how old he is in Python. I want to give an assertion error when the input is 0 or lower and when the input is not an integer, so for example the user types something like a comma or something else. This is what I have now test = input("How old are you?: ") assert test > 0 and type(test) == int, "Must be more than 0 and only numbers"  And this doesn't work, because when the user types in an integer like 15, it is considered a string and > is not allowed between a string and an integer. So I tried to make the input an integer, like this: test = int(input("How old are you?: ")) assert test > 0 and type(test) == int, "Must be more than 0 and only numbers"  This above works for the first assert. When the user puts as input -1 or 0, it gets an assertion error. However, it does not work for the second assert, because the type is already an integer. How can I solve this?


Need help identifying a comic book about a wizard

I need help with identifying the comicbook, what follows is my best effort to gather whatever I remember from reading it years ago (circa year 2000, but I'm positive it was older than that):   The main character was a guy with white hair, who wanted to become powerful.  Through some training and a deal of some kind he was able to become a mage of sorts. The training was set on some other world, or possibly even parts were happening in different dimension. His powers might have had something with travelling between dimensions, but I'm not  100% sure. Also, I seem to recall there was a hard limit of how many times he could use them. Then followed a part where he was famous, but someone framed him into a scandalous plot (it was a sexual scandal, I think) using his clone or a doppelganger. At the end of the issue     the main character is seen trapped in some strange state, unable to move or escape using his powers (this might have to do something with the deal he made earlier). I remember the scene at the end as this: he is suspended in mid-air, his friends look at him in disbelief while some malevolent figure explains to them that he is now trapped forever.  His name was the title of the comic. The second and third parts were set on futuristic-looking planet.   Rings any bells? I'd like to read it again only I can't google it out.


When you write the command name wrong, bash often does this:  septi@norbert:~$ good No command 'good' found, did you mean:  Command 'gold' from package 'binutils' (main)  Command 'gmod' from package 'gmod' (universe)  Command 'goo' from package 'goo' (universe)  Command 'god' from package 'god' (universe)  Command 'geod' from package 'proj-bin' (universe)  Command 'gord' from package 'scotch' (universe) good: command not found   Or sometimes it does this:  septi@norbert:~$ nftp No command 'nftp' found, but there are 23 similar ones nftp: command not found   Is there any way to ask bash to show these 23 similar commands for me? And, is there a way to show similar commands, including those that aren't yet installed, instead of running the application, ftp for example?


How to access a site you host from within your own network?

I have web site being hosted on my computer, so that mysite.com is served from one of my machines. However, even though everyone else can access this site normally, if I type its name (or, indeed, any subdomain such as x.mysite.com), I can't get the site to show. Now, if I edit the hosts file to redirect mysite.com to 192.168.1.5, everything is fine.  However, this is not a viable solution because then I need to edit the hosts file on every machine on the network. So, my question: is there an easier way?


Calculate a specific day's Date to another date, and print their difference?

Today is 3/26/2016. I want to Print out how many days are until  4/05/2016 ex.  The answer is 10 days. I want to do this with Javascript Code.  With standard javascript or with the use of a Library or Framework. Just to calculate the Difference between two dates. Easy, no too complicated.  InsertDateHere     -------         3/26/2016     InsertDateHere  ------  4/05/2016     ResultHere     -------------- AnswerHere ("10" ex.)  if anyone can help, please Do. Thanks a lot People!


Recovering Original Win8 to Toshiba Satellite c850 after formatting hard disk

I have Toshiba Satellite c850 B516 with Original Win8 installed. I accidentally formatted the internal hard disk. There is no serial number written on the bottom of my laptop. How can I recover my original Win8 even if all my personal data is lost.


I have a lot of sections in my beamer presentation. Because of that I cannot see all of them in the header.  Since I'm using the Darmstadt theme, it seems that the header has enough space two write the sections in 2 lines.  How can I do that? I could use other theme too.  \documentclass[hyperref={pdfpagelabels=false},xcolor=dvipsnames]{beamer} \usepackage{lmodern} \usepackage[utf8]{inputenc} \usepackage{subfigure} \usepackage{wasysym} \usepackage{pdfpages} \usepackage{beamerthemeshadow} \usepackage{caption} \usepackage{xcolor} \usepackage{multicol} \usetheme{Darmstadt}  \begin{document}  \begin{frame} \titlepage \end{frame}  \begin{frame}\frametitle{TOC} \begin{multicols}{2} \tableofcontents \end{multicols} \end{frame}  \section{Section 1} \begin{frame} \frametitle{Section 1}  \end{frame}  \end{document}   Thanks


"We propose the session focuses on ..." or "We propose the session focus on ..." Which is correct?

I understand a verb in English needs to match the sentence subject. Is the subject here "we" or "session", or am I seeing this incorrectly?


How to publish my project on the software center?

I have a project which enable to execute commands with the voice, .  How can I publish it on the ubuntu's software center?


Bender Rodriguez. The lovable robot with a SERIOUS alcohol problem.  One thing always perplexed me, though. How does he store everything?     How did he get all these treasures? He stored them in his abdomen for years on end. But many of these riches are far larger than his midsection (see the bender to the right, one row back, and the bender one back and one toward the center of the pirate).  And we see him do this with his majestic midriff multiple times throughout the series.   But how is this terrific thorax possible? In- and Out-Of-World explanations welcome.


Subscripts and superscripts on accented math characters

\documentclass{article}  \begin{document}  ${x_i}^j$ works as expected but not with an hat as in ${\hat{x}_i}^j$. The way I found to make it work is $\mbox{$\hat{x}_i$}^j$.  Is there an nicer solution?   \end{document}


Can $\|f\|_p\to\infty$ arbitrarily slowly? (Looking for hints.)

Given $f$ is Lebesgue measurable on $(0,1)$ and not essentially bounded, is it true that to every positive function $\Phi$ on $(0,\infty)$ such that $\Phi(p)\to\infty$ as $p\to\infty$ one can find an $f$ such that $\|f\|_p\to\infty$ but $\|f\|_p\leq\Phi(p)$ for all sufficiently large $p$?  My gut instinct tells me "no", but I don't have any logical arguments to back me up. If anyone has a suggestion as to where to start when thinking about this problem, I would appreciate it. (This question is asked in Chapter 3 of Rudin's Real and Complex Analysis text, which is entitled "$L^p$ Spaces".


I was under the impression that Stack Exchange sites were forums, or forum-like objects.  If they are not forums: Why aren't they? What defines a forum?


Canadian citizen needs insulin in US during lockdown

I am a 67 years old Canadian Citizen who came to US to visit my son on Feb 29th, 2020. Can't go back due to Covid19, how can I get insulin?


Prove that for every prime number $|\{1\leq x \leq p^2 : p^2 | (x^{p-1}-1) \}|=p-1$

Show that for every prime number $p$:  $$|\{1\leq x \leq p^2 : p^2 | (x^{p-1}-1) \}|=p-1$$  I'm not really sure how to approach this, any ideas?


Filtering ping output through multiple pipes fails

Trying to capture only the packets return time from ping output, I issued  $ ping 192.168.0.1 | grep -o '[^ =]* ms'   and it worked, displaying each packet time when it arrived. Since I also wanted to get rid of the unit of time, thought this would suffice:  $ ping 192.168.0.1 | grep -o '[^ =]* ms' | grep -o '^[^ ]*'   But, to my surprise, it hangs, showing no output. Replacing the first command with an echo of a sample line from ping output, however, works as expected (it outputs 5.07):  $ echo '64 bytes from 192.168.0.1: icmp_seq=10 ttl=64 time=5.07 ms' | grep -o '[^ =]* ms' | grep -o '^[^ ]*'   I found other means of getting only the time without the milissecond unit, but still: What is the issue with ping command? Why is passing it through one pipe is OK, but not through two?  PS: These below also fail, while their echo versions succeed, thus the problem can't be with grep  $ ping 192.168.0.1 | grep -o '[^ =]* ms' | sed 's_ ms__' $ ping 192.168.0.1 | grep -o '[^ =]* ms' | cut -f 1 -d ' ' $ ping 192.168.0.1 | cut -f 7 -d ' ' | cut -f 2 -d '='


Write an expression for $(\cos θ + i\sin θ)^4$ using De Moivre’s Theorem.

Obtain another expression for $(\cos θ + i \sin θ)^4$ by direct multiplication (i.e., expand the bracket). Use the two expressions to show  $$ \cos 4\theta = 8 \cos^4 \theta − 8 \cos^2 \theta + 1,\\ \sin 4\theta = 8\cos^3\theta \sin\theta − 4 \cos \theta\sin \theta. $$ You may use the well-known identity: $\sin^2 \theta + \cos^2 \theta = 1$, but do not use any multiple angle formula.  I got using DMT that $(\cos \theta + i\sin \theta)^4 = (cos 4\theta + i\sin 4\theta)$ and using direct multiplication, I got $\cos^4\theta + \sin^4\theta - 4\cos^3\theta*\sin\theta*i - 4\cos\theta \sin^3\theta i - 6\cos^2\theta\sin^2\theta$


How can I check through command-line the computer form(Desktop, notebook or All-in-one)?

For a very specific reason I need to check the computer form factor(Desktop, Notebook or All-in-one) remotelly, using a command  through the command-prompt, powershell or vbs(Windows 7/8 systems).   There is any way to do such thing?  Thanks in advance.


How long does it take to update my “Hot Meta Post up-vote” in home page?

I have up-voted a question in Meta Webmasters Stackexchange. That question is available in home page under Hot Meta Post list. But my count has not been updated. Why it’s not updating quickly? If it will take time means what’s the approximate time duration?  Screenshot for reference:


If i use two or more lighters to heat an iron spoon, will it melt?

If i start heating an iron spoon with one lighter and i start adding more lighters to that "heating system", can the temperature increase so high that it would melt the spoon ?


How does wizard & cleric spell preparation and casting work?

In 3.X wizards had spellbooks, while clerics had their entire spell list, but they both memorized/prepared spells every day from those lists, and had a certain number of slots for preparing spells in.  Now in 5e preparing spells and spell slots aren't the same thing. What's going on here? How does their spellcasting work now?


Can Windows 7 boot from an external USB or FireWire drive?

Other operating systems can boot from external USB or  drives, but Windows has, to my knowledge, never had this ability, at least not officially out of the box.  How is it with Windows 7? Can it be installed to and booted from an external drive?


Why is there always a capacitor on input and output of a voltage regulator?

Looking at the datasheet I can see that the voltage regulators are not just a zenner diode inside, they are complex devices. I have noticed that there is always a capacitor at the input and another one at the output. An example is the uA7800 series fixed voltage regulators.  I have read that one of them is to "stabilize the circuit operation" while the other is to "reduce ripple on the output". Looking at the datasheet, why do they have this fixed value? And if they do have a fixed value then why not just fabricate them into the voltage regulator itself? e.g for the uA7800 series it is 0.33uF at the input and 0.1uF at the output. It is not explained why they have these values.


So if you look a the image I extruded the side and filled a face at top, the bottom is empty and I wanted to create a loop around the 3 sides but it will only appear for one side any tips.


When I have read this article '' i still don't understand the difference between difference between Causality and Correlation?  I understand about causality but not correlation. Maybe you have any concrete example?  Thanks!


If $q$ is coprime to $a$ then $a\mid nq-1,\,$ so $q$ is invertible mod $a$

I think the following is true:  If $q$ is coprime to $a$ then $a\mid (nq-1)$ for some $n\in\mathbb Z$.  I have started to first reducing $n\in\mathbb Z$ to $n\in\{1,\ldots,a-1\}$ and then considering all the cases $q = ka + j$ for $j=1,2,3,\ldots,a-1$. I stopped at $j=3$ and found that this is kinda messy. Does anyone have an elegant proof for this (maybe using some results from number theory)?  [Note: question has been generalized from prime $q\nmid a$ to $\,q$ coprime to $a$]


Replace dash with idem/eadem in verbose-trad1

I'm currently using biblatex with the verbose-trad1 style.  Now, I saw in the bibliography that the author gets replaced by a dash when it is multiply referenced because he/she has more than one book:    (this is an example from ).  Now, I was asked to replace the dashes with idem/eadem. Is it possible? The author of  wrote     With biblatex, the author can be replaced by a dash (or “idem”) in the bibliography   so I think it is possible, but.. How?  EDIT: I already knew that there was a solution for the problem (in fact I already linked the question marked as duplicate in the original text).  Now, since the author of the other question asks for a way to put idem/eadem for partial matches, and he already knew a way to put it for complete matches, I assumed that there was another way to put idem/eadem instead of dash in the bibliography already embedded in some style or requiring something else. I was asking for that style or something else...


Timestamp on "others with this badge" page

I'm looking at the pages that show "others with this badge", such as :     The time of day is of very little usefulness, and could probably be removed. The year is missing in some cases, and present in others such as '12.   This feels weird.  I thought it was just omited for the current year, but here it shows December of 2013 without an '13. It would be much cleaner in all cases if it just showed in dd MMM yyyy format, such as:  "Awarded 22 May 2014 to"   Just a suggestion.  Thanks.


Virtual method, but non-virtual destructor

class A { public:     virtual void x() = 0;     virtual void y() = 0;     virtual int z() = 0; };  class B: public A { public:     void x();     void y();     int z();     void w(); };  class C: public A { public:     void x();     void y();     int z(); };   "Class 'i' has virtual method 'j' but non-virtual destructor", where i = A, B C, and j = x, y, z  Do I need a virtual destructor?


Are traditional IRAs worse than taxable brokerage accounts at high incomes?

Brokerage accounts are seen as relatively tax-inefficient, since you invest with post-tax dollars, and growth is taxed upon realizing gains. The traditional IRA allows you to deduct contributions and defer taxes until you take distributions in retirement ...  Unless you are covered by a retirement plan from work and make over   $71,000/year if single, or $118,000/year if married filing jointly.   The numbers above come from . Above those thresholds, you can still make contributions to a traditional IRA, but those contributions will be post-tax. Distributions are taxed as ordinary income, excluding post-tax principal.  Similarly, eligibility to make direct Roth IRA contributions phases out to zero according to a :   $131,000 if single, or $193,000 if married filing jointly.   Looks to me that someone who cannot make direct Roth IRA contributions also cannot deduct traditional IRA deposits from income.  Assume   investment period is 20 years, is some garden variety ETF (VTI/VXUS/etc), those investments return 5%, the current marginal tax rate is 28%, the expected marginal tax rate at retirement is 25%, the long term capital gains rate is 15%, the entity is not eligible to make Roth IRA contributions, and 401k contributions are already maxed out.   A $5000 of gross income contribution into a traditional IRA at retirement might grow to an after-tax sum of:  (5000) * (1 - 0.28) * (1 + (1.05 ** 20 - 1) * (1 - 0.25)) = $8064   Instead, since contributions were going to be taxed anyway, why not put it in a brokerage account? Then you could claim the favorable long-term capital gains rate.  (5000) * (1 - 0.28) * (1 + (1.05 ** 20 - 1) * (1 - 0.15)) = $8659   All I found was , and the accepted answer says to still make a traditional IRA contribution, but I still don't see why that would be a good idea. What am I missing here?


In-universe that is. Out-of-universe explanation may just be that it sticks out against the black Vader / backgrounds.  White strikes me as an especially poor choice of colour for uniforms. Except for snow, it sticks out like a sore thumb.  Is it because, like the , they engaged in a lot of melee combat where it was important to easily see your friendlies in chaos? Was white an important part of Empire symbolism?


Why does ASP.NET webforms need the Runat="Server" attribute?

Why do I have to specify runat="server" on all my ASP.NET controls when it is a mandatory attribute and server is the only option available in my limited knowledge of ASP.NET, and I get an error if I don't use it?  I do understand that I can optionally use it on my HTML tags, and I do understand the client/server paradigm and what it is actually specifying.  Is it a redundant tag that could just be implied by the control being an ASP.NET control, or is there an underlying reason?


My AC adapter reads...           Output: +12V DC symbol 12.5A           Input:  100-240V~                   50-60Hz 2.5A  I would like some clarification on if i'm reading/understanding this correctly. The input is the range in which the brick will work when I plug it into the wall and the output is what the brick pushes out for the computer (what the computer need to draw to power on when I turn it on). If say I were to have 20 of these same computers plugged in would I trip a standard 120V / 20A breaker in my home?   I know you add the Amps and make sure the total doesn't go over the 20A but am I using the 2.5A that the brick pulls or the 12.5A. Kind of a stupid question but its something that's always confused me when I look at it.


Trying to factor $x^4-3$ over $\Bbb{F}_p$ with $p\equiv 3\mod{4}$

So I am trying to show that $f(x) = x^4-3$ will factor over $\Bbb{F}_p$ when $p\equiv 3\mod 4$, with $p\neq 3$. Specifically, I am trying to show that $f$ will factor into irreducibles such that there is at least one factor of degree 2.  My Work So Far  So if I assume that it can be factored, we would have $$ x^4-3 = (x^2+ax+b)(x^2-ax+d) = x^4 + (b+d-a^2)x^2 + a(d-b)x + bd.$$ Because we want the linear term to be 0, we need either $a=0$ or $d-b = 0$. Now if $a=0$ we get that $b=-d$, so $-b^2 = -3$. That is, $3$ is a square. If $d-b = 0$, then we would have $b^2 = -3$, so $-3$ is a square. Because $-1$ is not a square when $p\equiv 3\mod{4}$, we know that one of $-3$ or $3$ must be a square, but not both, so $a=0$ or $d=b$, but not both.  If $a=0$, that is $3$ is a square, then we have $f(x) = (x^2 +b)(x^2-b)$. Then one of $b$ or $-b$ is a square, but not the other, so $f$ will factor into two linear terms and a quadratic. So this case works.  The trouble I am having is with the second case. If $d=b$, then we have  $$ f(x) = (x^2 + ax + b)(x^2 -ax +b)$$ with $2b = a^2$. This is where I get stuck. How do I know that such an $a$ can exist?  Edit: If there is a better approach to solving this, that would be great to know as well. I haven't been taught any of the relevant number theory to solve this, so I'm kind of out of my element here.


Deleted comments persist in the global inbox

A comment directed to popular demand, posted and deleted in my question about high rep users is still in my and popular demands' global inbox.  Additionally, edits do not affect the global inbox.


Derivative of vector product with respect to a vector

I would like to derive the following expression with respect to a vector $x \in \mathcal{R}^N$:   $a a^T b$  where $a, b$ are vectors in $\mathcal{R}^M$.  My idea is to apply the following  $ \frac{\partial a}{\partial x} a^T b + a (\frac{\partial a}{\partial x})^T b + a a^T \frac{\partial b}{\partial x}$ but it is dimensionally wrong.   In fact: $\frac{\partial a}{\partial x} a^T b$ has dimension: $(MxN) (NxM) (Mx1)$ or $a (\frac{\partial a}{\partial x})^T b$ has dimension: $(Mx1) (NxM) (Mx1)$ that are really dimensionally wrong.  I'm assuming that the derivative of a vector $a \in \mathcal{R}^M$ with respect to another vector $a \in \mathcal{R}^N$ is a matrix $a \in \mathcal{R}^{MxN}$.   Moreover, even in the very simple example: I want to derive $a^T b$ with respect to $x$: $(\frac{\partial a}{\partial x})^T b + a^T \frac{\partial b}{\partial x}$, the first addendum seems to be a column vector in $\mathcal{R}^N$ while the second one is a row vector in $\mathcal{R}^N$. What am I doing wrong? I know I can fix this by transposing the function $a^T b$ when partially deriving with respect to $a$ (then the first addendum becomes $b^T \frac{\partial a}{\partial x}$) but I would like to know if there is a generic rule for that.  Thank you to anyone that can provide to me some hints.  Marco    My question is a bit different with respect to  since that is the differentiation about the transpose of a vector while here I'm questioning about the dimensionality of vector product derivative.   Moreover, I add a dummy question that may help me in solving this: In case of a derivative of scalar-vector product, i.e. $\frac{\partial (c a)}{\partial x}$, with $c \in \mathcal{R}, a \in \mathcal{R}^M$ and $x \in \mathcal{R}^N$, I would say that the derivative is $\frac{\partial (c a)}{\partial x} = \frac{\partial c}{\partial x} a + c \frac{\partial a}{\partial x}$. Now, the first addendum has a wrong dimensionality: (1xM) (Nx1). Now, I know that the things works if I do: $\frac{\partial (c a)}{\partial x} = a \frac{\partial c}{\partial x} + c \frac{\partial a}{\partial x}$, i.e., if I set the scalar on the right side before deriving with respect to $c$. In this case I know that, for dimensionality, $a c$ is more correct than doing $c a$ but I would like to know if there are some rules that I'm aware of. Then my question is: why do I have to do this?


Is there any way to erase personal information from my phone that has already been stolen?

My phone has been stolen. I do not want the thief to have access to any of my personal information such as calls, texts, and information saved in the phones contents. Is there any possible way I can get this information erased from my phone?