I need to strip part of JWT token and I am courious which one is faster, or less complex internally.  Example input string:  const input = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOjMsInR5cGUiOjAsImlhdCI6MTU4MTk3NDk1MCwiZXhwIjoxNTgxOTc4NTUwfQ.oEwxI51kVjB6jJUY2N5Ct6-hO0GUCUonolPbryUo-lI"   Which one of those methods is faster?  const output =  input.split('.').slice(2,3).join('.');   const output =  input.replace("eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.","");   const output =  //REGEX replace   I not found any informations about speeds of those methods and I am not exactly master in making tests :D

I need to get execution time in milliseconds.  I originally asked this question back in 2008. The accepted answer then was to use  However, we can all agree now  that using the standard  API is more appropriate. I am therefore changing the accepted answer to this one.


My progress is that I applied Hölder’s for this,  $3(a^2b+b^2c+c^2a) \frac{(ab^2+bc^2+ca^2)}{abc} \geq (a+b+c)^3$   whereas  $3(a^2b+b^2c+c^2a) \frac{(ab^2+bc^2+ca^2)}{abc} =  (1+1+1)(a^2b+b^2c+c^2a)(\frac{b}{c} + \frac{c}{a} + \frac{a}{b})$  And I was lost here. Can anyone check or continue this proof?

if $x,y,z$ are positive real numbers,Prove:$$3(x^2y+y^2z+z^2x)(xy^2+yz^2+zx^2)\ge xyz(x+y+z)^3$$ Additional info:$\sum_{cyc}$ denotes sums over cyclic permutations of the symbols $x,y,z$. I'm looking for solutions and hint that using Cauchy-Schwarz and AM-GM because I have background in them.  Things I have done: Writing Left hand side in expanded form:$$LHS=3(\sum_{cyc}x^3y^3+\sum_{cyc}xy^4z+3x^2y^2z^2)$$ Right now I don't have good idea were to start(Is expanding and looking for AM-GM is good?).So any hint is appreciated. Source : This inequality can be found as Problem 42, page 13, in the book "Old and New inequalities" by Titu Andreescu, where it is attributed to Manlio Marangelli.


I am unable to highlight the intersection area of $x^2+y^2=2x ; x=y^2$ using TikZ, I have tried two different codes by using pgfonlayer, as mentioned below, one is running but giving output as filling shade in the form of triangle, other is not running which I have shown below in comments.   Please help... thanks   \documentclass{article} \usepackage{tikz,pgfplots} %\usepackage[x11names]{xcolor} \usepackage{tikz} \usetikzlibrary{intersections} \pgfdeclarelayer{bg}    % declare background \pgfsetlayers{bg,main}  % order of layers (main = standard layer) \pgfplotsset{compat=1.13} \usepackage{amsmath} \usetikzlibrary{positioning}      \begin{document}     \begin{tikzpicture}   \draw(1,0)circle(1cm); % DRAW CIRCLE \draw[blue,line width = 0.50mm]   plot[smooth,domain= -2:2,variable=\y] ( {(\y)^2},\y);  \draw (-2,0)--(4,0) (0,-2)--(0,4); \draw(1,1)node(a){A}--(1,0)node(c){C}; \draw(2,0)node(b){B}--(0,0)node(o){O};   \begin{pgfonlayer}{bg}    % select background \path [fill=blue!50] (o.center) --(a.center) --(b.center) -- cycle;  \end{pgfonlayer}  I have tried the following code as well, but it is showing some error, please help.  %   \begin{pgfonlayer}{bg}    % select background %   \clip plot[smooth,domain=0:2] (\sqrt{1-(x-1)^2}, \x); %   \fill[red]  plot[smooth,domain= -2:2,variable=\y] ({(\y)^2},\y); %   \end{pgfonlayer} \end{tikzpicture}  \end{document}

Unable to fill color in the intersection region of $y =\sqrt{x}, y =x , using tikz by the given code.  Please help, thanks  \documentclass{article} \usepackage{tikz,pgfplots} %\usepackage[x11names]{xcolor} \usepackage{tikz} \usetikzlibrary{intersections} \pgfdeclarelayer{bg}    % declare background \pgfsetlayers{bg,main}  % order of layers (main = standard layer) \pgfplotsset{compat=1.13} \usepackage{amsmath} \usetikzlibrary{positioning}      \begin{document}      \begin{tikzpicture}[domain=0:2, scale = 0.75, dot/.style={circle,fill,inner sep=1pt}]     \draw(-4,0)--(4,0);     \draw (0,-4)--(0,4);      \draw(0,0)--(3,3);     %\draw[black, line width = 0.50mm]   plot[smooth,domain=0:2] (\x, {\sqrt{\x}});      \draw[blue,line width = 0.50mm]   plot[smooth,domain= 0:2,variable=\y]     ( {3(\y)^2},\y);     \draw(1,0)--(1,1);     %\draw[black, line width = 0.50mm]   plot[smooth,domain= -2:2] (\y,  {(\y)^2});     \draw(2,3)node($y=x^2$){$y=x$};     \draw(5,2)node($x=y^2$){$\sqrt{x}=y$};     \draw [left=.2cm](0,0)node(o){O};     \draw[right=.1cm](1,1)node(a){A};       \begin{pgfonlayer}{bg}    % select background     \clip plot[smooth,domain=0:2] (\x, {\x});     \fill[red]  plot[smooth,domain= 0:2,variable=\y] ({(\y)^2},\y);     \end{pgfonlayer}     \end{tikzpicture}  \end{document}


Say I have two files (file1.txt & file2.txt).  file1.txt: (contains only list of words, one per line)  Car Ricky   file2.txt: (contains lines (phrases) using words from file1.txt and more)  he has a Car there is no food I have a book road is straight Ricky is a good student   The output should be:  he has a Car Ricky is a good student

Does anyone know of any linux tool specifically designed to treat files as sets and perform set operations on them? Like difference, intersection, etc?


My company is planning to develop iphone-native-applications.  I'm good with Linux.  The questions are:  Do we need a MAC machine to develop iphone-app?  Can a normal development-framework like NETBEANS / ECLIPSE suffice?  What are the other pre-requisites that i might need?  Any help is very much appreciated.  Plz, pardon with me being totally naive with this IPHONE :-)  Thanks

I've heard that you need to get a Mac if you want to develop iPhone apps. Is this true?   Is it possible to develop iPhone apps using Linux? If yes, what do I need and where do I download the necessary tools?


I've been a teacher.     VS       I was a teacher.   I no longer teach, but I used to teach. Can I used "have been" here?  I have been a teacher

What is the difference between the three sentences below?   I have been married with her for three years. I was married with her for three years. I married her for three years.


Hi I using java and testng for my test suite and allure report for reporting , issue is I am not able to figure out how to implement condition where  Blacklist specific header value Logged response only if test case failed.  I am using Listners at class level package testListnersT;  import com.aventstack.extentreports.markuputils.ExtentColor; import com.aventstack.extentreports.markuputils.MarkupHelper; import configurationAPI.BaseConfiguration; import io.qameta.allure.Attachment; import io.restassured.RestAssured; import io.restassured.filter.log.LogDetail; import io.restassured.filter.log.RequestLoggingFilter; import io.restassured.filter.log.ResponseLoggingFilter; import org.testng.ITestContext; import org.testng.ITestListener; import org.testng.ITestResult;  import java.io.ByteArrayOutputStream; import java.io.PrintStream;  public class ListenersT extends BaseConfiguration implements ITestListener {      private final ByteArrayOutputStream request = new ByteArrayOutputStream();      private final ByteArrayOutputStream reponse = new ByteArrayOutputStream();      private final PrintStream requestVar = new PrintStream(request, true);      private final PrintStream responseVar = new PrintStream(reponse, true);       public void onFinish(ITestContext arg0) {         // TODO Auto-generated method stub      }      public void onStart(ITestContext arg0) {         RestAssured.filters(new ResponseLoggingFilter(LogDetail.BODY, responseVar),                 new RequestLoggingFilter(LogDetail.BODY, requestVar));     }      public void onTestFailedButWithinSuccessPercentage(ITestResult arg0) {         // TODO Auto-generated method stub      }      public void onTestFailure(ITestResult result) {         childTest.info(result.getThrowable());         childTest.fail(MarkupHelper.createLabel("FAIL", ExtentColor.RED));     }      public void onTestSkipped(ITestResult arg0) {         // TODO Auto-generated method stub     }      public void onTestStart(ITestResult arg0) {         // TODO Auto-generated method stub      }      public void onTestSuccess(ITestResult arg0) {         logRequest(request);         logResponse(reponse);     }       public byte[] attach(final ByteArrayOutputStream log) {         final byte[] array = log.toByteArray();         log.reset();         return array;     }      @Attachment(value = "request")     public byte[] logRequest(final ByteArrayOutputStream stream) {         return attach(stream);     }      @Attachment(value = "response")     public byte[] logResponse(final ByteArrayOutputStream stream) {         return attach(stream);     }  }  Below is sample test code  @Epic("Entity")     @Story("Service")     @Description("Test Desc")     @Test(priority = 1, groups = {"testOne"})     public void verifyTEST(Method method) {              domainURL = env.apiBaseURL();                       body = JsonBuilderFactory.buildObject()                 .add("id", 12345)                                 .getJson();          response = given()                 .config(config.logConfig(LogConfig.logConfig().blacklistHeader("key")))                 .header("Content-Type", "application/json")                 .header("key", Key())                 .body(body.toString())                 .post(domainURL);         assertThat(response.path("statusMsg").toString()).as("").contains("SUCCESS");     }

I am using rest-assured and allureRestAssured for testing api given().header("Content-Type", "application/json")                 .header("key", key()).filter(new AllureRestAssured())                 .body(body.toString())                 .post(baseURI);  Problem here is its logged headers also , which contains auth key , which I dont want to be exposed in report generated , how can I ignore that .


Is there a general consensus about whether the universe is deterministic? Is it still up in the air?  I have attempted to read other physics.stackexchange answers and do some independent research, but I'm not a physicist and most literature is beyond my comprehension. If you answer this question, I would most appreciate it if you could attempt to explain it as simply as possible. As soon as I have to start to look up theories or definitions that are used, the web pages that explain it generally go over my head.  The easiest way to phrase my question that I can think of:  Assume there is a being existing prior to the big bang, with infinite intelligence, physics knowledge, memory, and time. The only limitation is this being can not time travel to observe the future universe. However, this being knows everything about everything as it currently stands. Once the big bang happens, could this being map out every interaction in our universe throughout all time?

What are the main problems that we need to solve to prove Laplace's determinism correct and overcome the Uncertainty principle?


#!/bin/bash  counter=2  while [ $counter -lt 19 ] do            username= head -n $counter ./user_sheet.csv | tail -n 1 | cut -d ';' -f1          psswd= head -n $counter ./user_sheet.csv | tail -n 1 | cut -d ';' -f2          full_name= head -n $counter ./user_sheet.csv | tail -n 1 | cut -d ';' -f3          group= head -n $counter ./user_sheet.csv | tail -n 1 | cut -d ';' -f4          second_group= head -n $counter ./user_sheet.csv | tail -n 1 | cut -d ';' -f5           sudo useradd $username -m -g $group -s /bin/bash -c $full_name          if [ second_group = LPGestionnaires ]         then                  usermod -a -G $second_group $user         fi          #echo "$username:$psswd" | chpasswd          ((counter++)) done echo Execution complete   The part where it says sudo useradd $username -m -g $group -s /bin/bash -c $full_name is the part that isn't working, my -g option isn't seeing the variable $group argument as an argument, when I execute my script it returns this: useradd: group '-s' does not exist  I'm pulling the data from a .csv file that is located correctly.  If anyone could help that would be great!  Thanks!

Is there a way to assign a value to a variable, that value which we get in terminal by writing any command?  Example command: sensors  From that we get CPU temperature. How can I assign this value to a temp_cpu variable?


In Ta-Pei Cheng's Relativity, Gravitation and Cosmology book, he stated the equivalence principle as  Physics in a frame freely falling in a gravity field is equivalent to physics in an inertial frame without gravity.  But from wikipedia, an  is defined as a frame of reference that is not undergoing acceleration. So why is the freely falling frame of reference in a gravity field, which is accelerating, an inertial frame?

Note: For the purposes of my question, when I refer to free fall assume it takes place in a vacuum.   From my (admittedly weak) understanding of the equivalence principle, falling in a gravitational field is physically indistinguishable from floating in interstellar space. This would make sense to me if gravity simply caused an object to move at a constant velocity. Moving at a constant speed, or floating in space, are just two different ways of describing an inertial frame, and are fundamentally no different. But free falling in a gravitational field means accelerating continuously, and doesn't an accelerating body experience a force? Then isn't free falling fundamentally different from floating in space?


How can I invite my Facebook friends to Stack Overflow? Is it possible?

Since we're all into this OpenID thing, I think it would be really useful (and quite easy) to implement a friend invitation feature that grabs a list of friends from one's webmail contact list with an option to choose who to invite to SO, SF or SU. Something in the line of Facebook's friend invitation and recommendation feature.


I'm looking for a query to achieve the following:  Current table format   user_id   meta_key    meta_value -------   --------    ---------- 1         address1    abc street 1         city        austin 1         state       TX   Desired output  user_id   address1    city         state -------   --------    ----------   ----- 1         abc street  austin       TX

I've created main SELECT statement like below. For every row in Base table (base on IDKey I've added columns with values from result of INNER JOIN of few tables.  SELECT   IDKey,    Name,    (select Amount from Table1 INNER JOIN Table2 ... where ID=IDKey) AS AmountTypeX,    (select Amount from Table1 INNER JOIN Table2 ... where ID=IDKey) AS AmountTypeY FROM BaseTable   BaseTable:  IDKey Name  ---------- 1     Ian 2     John 3     Ann ...   INNER JOIN of few tables Table1, Table2... :   ID Amount Type -------------- 1  100    X 1  200    Y 2  300    X 2  400    Y 3  500    X 3  600    Y ...   Result looks like:  IDKey  Name  AmountTypeX  AmountTypeY ------------------------------------- 1      Ian   100          200 2      John  300          400 3      Ann   500          600 ...   Do you have any suggestion how to avoid this nested SELECT statements in the main query at the begining and made this query simpler and more effective ?  I wast thinking about PIVOTING of the INNER JOIN result to look like below (all data for particular ID in one row) and then JOIN with main query but Have no idea how to do this and is it possible.  ID  X   Y ----------- 1   100 200 2   300 400 3   500 600 ...


Is there any simple way to estimate the VC dimension for GBM? Or, for more specific implementation XGBoost?   XGBoost usually has large variability when training on a dataset with less than 500 samples more than 1000 features. Is there any way to estimate the model complexity of XGBoost with certain hyperparameters?

What is the  of a decision tree with k splits in two dimensions? Let us say the model is CART and the only allowed splits are parallel to the axes.  So for one split we can  and then for any labeling of the points we could get perfect prediction (i.e.: shattered points)  But what about 2 splits, or any general k?


I want to play on Minecraft servers, I can get on, but can't do anything, I can only play like one day per month. Do I need the latest version of Java or something? I am now using OpenJDK Java 7 Runtime to play Minecraft. By the way, the happened after I turned off my computer during the upgrade to 14.04 LTS. Before it was all normal. And now I am back to 12.04. Thanks to whoever that helps.  I already got Java 8 but there's a problem, I can't even play Minecraft now! When I go in one of my worlds this comes out:  AL lib: (EE) alc_cleanup: 1 device not closed pure virtual method called terminate called without an active exception   Now what? :/

How can I install Java on Ubuntu 12.04?  I have:    Java(TM) SE Runtime Environment (build 1.7.0_21-b11) Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)


I was searching through the internet to find PCI Express card edge connector footprints / technical drawings / pin spacing / layout of the module cards that you stick in these connectors you can find on a modern PC/server motherboard.    I wasn't able to find anything so I thought I could maybe ask here? I found some for Altium Designer which I don't have access to and also I am using (Autodesk) Eagle.  If you are wondering, I wanted to create a PCIe 3.0 x8 card that could hold two M.2 NVME SSDs since I could not find this anywhere either. Everyone only sells the type that holds one NVME (PCIe) and one SATA SSD. This is not what I need.  M.2 NVME interface is basically just a PCIe x4 interface, in another form factor. Therefore I don't see a problem with making a x8 standard card for PCs/servers that could hold two of those and properly route their interfaces.  Can anyone help? Thank you!

I can see this as being 50/50 between here and Eng.SE, so I decided to ask here as it deals with the PCI Express standard.  I'm attempting to create a library of PCI Express card edge footprints in Altium Designer, but I'm running into two dilemmas as to how the Card Electromechanical Specification lays out the the card edge dimensions. The image below is a snippet of the mechanical spec:    The two issues I'm having are:   The length (or, I suppose, height) of the normal-size pins are not specified. I was able to infer based on the height of the PRSNT2# pin and the difference in distance between edge of pin to edge of card that the normal pin should be 4.20mm high - is that correct? The distance of B12 to the key centerline is specified as 1.50mm, but not the distance in the other direction, that of B11 to the centerline. I'm a little uncomfortable making the assumption that the two are the same and that the pitch between the pins is 3.00mm - can anyone confirm (or deny) this?


In Google "documents" (not Spreadsheets), I've a script to insert Date. How do I create a keystroke to activate the script?

This question specifically applies to Google Documents, not Google Spreadsheets (but if the answer applies to both, all the better).  Google Documents has built-in . I would like to define my own key binding or shortcut so that I can run a user-defined script on the document directly without using the mouse. For scripts that I want to run often, having a key binding or shortcut I can press saves me wasted motion from having to use the mouse to pull down a menu and run the script.  I have scoured the  and found no mention of allowing this level of customization.    Do I conclude that Google did not include this feature?  I have not investigated possibilities of using Firefox-specific extensions but that would be my next approach (e.g., ).  Note that this is not the same question as asked in  .


I have this  Power MOSFET. In the datasheet, it is given as the Gate Threshold voltage is 3V maximum. But that is for a condition of drain current in microamps. But, my condition is, I require a continuous drain current of 5A from a 10V source with Gate Source voltage as 10V. Whether can I use this part? (Mainly asking for the threshold voltage and the maximum drain source voltage)

This is a screenshot of IRF9640 MOSFET datasheet. Will you please tell me, what is meant by max and min value of Vgs threshold voltage. Also what they mean by test condition.  Whether the max and min values are only applicable for specified test condition? What will be the threshold voltage for a switching circuit and how the range varies?  My doubt is, for p channel mosfet to turn on Vgs < Vgs(th). For IRF9640 in what volt it will turn on -3 or -5? When i used in my application Vs is 6v and Vg is 3v hence Vgs=-3v but it won't turned on, Why? It turned on when Vgs=-3.3v.  If we consider -2v as threshold, it should turn on when Vgs=-3v. Why they given a range for threshold voltage. Whether we have to test each mosfet to know their threshold. What i am pointing is that, if we have two IRF9640, will Vgs(th) is differ from each other?


I want to ask if I delete a pic from iCloud online, does it get deleted from the iPhone too?

If I delete a photo from my iCloud will it also be removed from my devices that are connected to my account?


It is difficult to see through a closed glass window from the inside of a well lighted room, when it is dark outside. However it becomes relatively easy to see outside, when the light in the room are switched off explain.

In day, when you look in the room through the window out, you can clearly see what happens outside. At night when it's dark outside but there's light inside you can look in the window but it becomes a mirror.  Why?


I have a scenario where I want to store values of command run output to array   I have a dat set like below  ID|SAL|COST|PER|TAG 1"|"10.1"|"12.22"|"10.1"|"A"  2"|"10.223"|"12.333"|"10.1"|"B"   after running the below command I am getting sum of column output as  awk -F"|" 'NR==1{for(i=1;i<=NF;i++){if ($i ~ /SAL|COST/){print i;}}}' demo.txt  2 3   But the issue is I want the generated output need to be stored in array I am using below approach not working using mapfile -t   mapfile -t array < <(awk -F"|" 'NR==1{for(i=1;i<=NF;i++){if ($i ~ /SAL|COST/){print i;}}}' demo.txt)   when I print echo "${array[@]}" it gives me only one output value not all the value  output: 3   **need all the output values need to be printed. when I echo array **  2 3

DATA SET file name "demo.txt"  ID|SAL|COL|PER|TAG|GER 1"|"1.11"|"2.22"|"1.1"|"2.2"|D" 2"|"1.234"|"3.234"|"2.2222"|"2.34"|"B" 3"|"1.234"|"35.23"|"3.2"|"2.34"|"A"   I have created a function which will automatically calculate decimal column sum below is the function I am calling that function in main.sh script   demo() { FILE_NAME="$1" COLUMN_NAME="$2"  alpha=( $(awk -F"|" 'NR==1{for(i=1;i<=NF;i++){if ($i ~ /'$COLUMN_NAME'/){print i;}}}' $FILE_NAME) )  for each in "${alpha[@]}" do    awk -F'"?\\|"?' '{T+=$('$each')} END { printf "%.2f\n", T }' $FILE_NAME   done  }   Script : main.sh   #function called in main.sh script   demo demo.txt 'SAL|COL|PER|TAG'   issue is how do i get the output into an array   below is the output i am getting need to store into array1   3.57 40.68 6.52 6.88   second array is this below output getting from another program   array2={3.57 40.68 6.52 6.88}   **so that I can match the array1 with array 2 position value    array1[0] with array2[0]  array1[1] with array2[1]  array1[2] with array2[2]  array1[3] with array2[3]    if all succeed should display success status as YES  i have solution which is partially working ... help me with some solution  so that i can store each value of an array to array1   FILE_NAME="$1" COLUMN_NAME="$2"  alpha=( $(awk -F"|" 'NR==1{for(i=1;i<=NF;i++){if ($i ~ /'$COLUMN_NAME'/){print i;}}}' $FILE_NAME) )  declare -a array=();  for each in "${alpha[@]}" do         #var=($(awk -F'"?\\|"?' '{T+=$('$each')} END { printf "%.2f\n", T }' $FILE_NAME))         mapfile -t array <<< "$(awk -F'"?\\|"?' '{T+=$('$each')} END { printf "%.2f\n", T }' $FILE_NAME)"         #awk -F'"?\\|"?' '{T+=$('$each')} END { printf "%.2f\n", T }' $FILE_NAME done  echo "${array[@]}"


I have a dropdown on my html page, when it is first loaded, it is set to a default value. But when a user changes the value, I'm checking the selected value against another text field. If the condition does not satisfy, I want to show an alert to the user and reset the dropdown.   I'm able to show the alert with my condition, but how do I reset the dropdown after showing an alert to the user.

I have the following HTML <select> element:  <select id="leaveCode" name="leaveCode">   <option value="10">Annual Leave</option>   <option value="11">Medical Leave</option>   <option value="14">Long Service</option>   <option value="17">Leave Without Pay</option> </select>   Using a JavaScript function with the leaveCode number as a parameter, how do I select the appropriate option in the list?


Any other designers have suggestions on how/where to find photography on luxury fashion designers?  I'm looking for legitimate licensing.  I know the main sites like Shutterstock, iStock, and Getty Images. Where do you go about finding more industry specific photographs though? A lot of the stock sites by nature focus on broad topics and subjects for mass appeal. Should I just try to find a professional fashion photographer that might be able to license me out some of his unpublished pieces - where would I even begin finding that?

I am running a web site design service for local small business owner. I want avoid legal issues on the images I use. Usually, the images found on Flickr are forbidden for commercial use. Where would be a normal channel to get pictures for commercial use with minimal cost? How can I validate that the picture I used has no legal risk?


I own the PHB, DMG and MM physically.  I've also downloaded the various free pdfs from the WotC site (Elemental Evil Player's Companion, various Unearthed Arcana, etc).  I find it convenient to be able to search through these pdfs via text matching and that I can carry them around all in my pocket. Not so with the PHB, DMG and MM; they live at home and must be searched through the good ol' fashioned way if ever I need to look something up.  Is there a (legal) way to aquire a digital copy of these core rulebooks (also Volo, SCAG, etc)?    Obviously I won't accept "scan 'em all in yourself" as an answer ('coz I'm a lazy millennial) but I will accept "no, there isn't" if there really isn't anything available to download (legally).   Also note that I am aware of the basic player/DM rules that are available but since it is cut down (understandably since it's free) I don't want that as an answer either.  Finally, there's this suspect looking site, (it's the first hit if you Google "lost mines of phandelver"); given that it appears to offer every D&D book ever for free, I'm guessing this is not legal? Assuming this is the case, I don't want that as an answer either.

As much as I like having the hardcover core rule-books in front of me, usually I read or reference most information for RPGs on my computer.  Unfortunately, my google-fu has failed me at finding places to buy a Player's Handbook PDF, or even whether said PDF exists at all.  My question is this: Is there any place I can go to legally buy a D&D 5e core rulebook PDF?  I'm not looking for the starter set or basic rules, since those are incomplete (and free), I'm just looking for the core books in PDF format.


I am currently having a problem with removing sudo access from a user. The user is not in the sudo group but is able to carry out sudo commands and I am not sure how I can restrict the user from carrying out sudo commands. I have tried using the sudoer file but Can't seem to figure it out. Thanks so much for the help !

If you give a user sudo privileges how can I remove the sudo privileges and make the user become just a regular user?  I used:  sudo adduser username sudo   Now I've changed my mind.


I've been looking for a chicken soup with matzo balls recipe that would duplicate my grandma's (she died without passing on the recipe.)  sounded like it would be close. I followed it to the letter, and let it cool in the fridge overnight so it would be easier to remove the fat.   When I took it out of the fridge, I was able to pull a solid layer of fat off the top, but the "soup" underneath is not liquid - it's gelatinous. Is this normal? If not, what did I do wrong? And is there any way to fix it? I had planned on giving jars of it to friends, but it looks pretty disgusting when cool, even if it does heat up correctly (which I'm not sure it does; it's reheating on the stove now.)

I made chicken stock recently from chicken thigh bones and skin (just needed the thigh meat and the bone-in-with-skin were cheaper).  After cooling it in the fridge I ended up with gelatinous semisolid stuff underneath a layer of fat a few mm thick.  I removed the fat, but am wondering whether the "stock" underneath it is useable for anything.


I'm using mysql_real_escape_string() on every INSERT before anyone asks. However, I want users to be able to type apostrophes but they come up as back slashes. However, I also want them to be able to use backslashes.  The users are trusted but is it possible to allow these characters whilst also preventing the possibility of an SQL injection?

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


Are there cases in which the inline keyword on a virtual method is not ignored by the compiler?  I am thinking for example to cases such as the following:  struct Interface {     virtual void f() = 0; };  struct Dummy : Interface {     inline virtual void f() override {} };  int main() {     Dummy a;     a.f();      return 0;   }   Can code like this be optimized?

I got this question when I received a code review comment saying virtual functions need not be inline.   I thought inline virtual functions could come in handy in scenarios where functions are called on objects directly. But the counter-argument came to my mind is -- why would one want to define virtual and then use objects to call methods?  Is it best not to use inline virtual functions, since they're almost never expanded anyway?  Code snippet I used for analysis:  class Temp { public:      virtual ~Temp()     {     }     virtual void myVirtualFunction() const     {         cout<<"Temp::myVirtualFunction"<<endl;     }  };  class TempDerived : public Temp { public:      void myVirtualFunction() const     {         cout<<"TempDerived::myVirtualFunction"<<endl;     }  };  int main(void)  {     TempDerived aDerivedObj;     //Compiler thinks it's safe to expand the virtual functions     aDerivedObj.myVirtualFunction();      //type of object Temp points to is always known;     //does compiler still expand virtual functions?     //I doubt compiler would be this much intelligent!     Temp* pTemp = &aDerivedObj;     pTemp->myVirtualFunction();      return 0; }


Ok so I have this question:   Two point charges of charge -2 µC and -3 µC respectively are separated by a distance of 15 cm. Point X is positioned at an equal distance away from each of the charges.      a. Determine the net electric field at X.     b. Find the point of equilibrium between the charges.   I've started writing out the formula for the electric field from charge -2 µC to point X, but I'm just confused about how you are supposed to do it when you don't know the distance between the charge and point X (the r or d value in the formula).

I am just very confsed about how to do these sort of questions where they give you a point in the middle of two charges. The farthest I've gotten in questions relating to coulomb's law, is using the formula \$F = {kq_1q_2 \over d^2}\$ to work out one of the unknowns when given two variables. Can someone please explain how you would do a question like this:  Two point charges of charge -2 µC and -3 µC respectively are separated by a distance of 15 cm. Point X is positioned at an equal distance away from each of the charges.      a. Determine the net electric field at X.     b. Find the point of equilibrium between the charges.


I have a database with full backup of almost 2GB. When I perform a full backup (without compression) and then compress it with winrar it become 140MB, but when I backup WITH COMPRESSION syntax the result is 315MB, and unfortunately after compression with winrar the size not changes. How can I use T-SQL for full compression at maximum level?

Daily we ship our SQL Server backups across the WAN. We need to minimize the size of these backups so it does not take forever.   We don't mind if our backup process takes a bit longer; as it stands we need to move 30gigs of compressed backup across the WAN that takes over 10 hours.   There are 2 options we have to get smaller daily backups.    Log shipping, which would mean we would have to restructure DR process.  Strip information out of the db and rebuild on the other side (drop non clustered indexes, pack clustered indexes at 100% - rebuild on the other side)   Both would involve a fair amount of work from our part. We are using SQL Server 2008 pro, all backups are compressed.   Are there any commercial products that can give us similar backup size to option (2)?    Is there a comprehensive script out there that will allow us to accomplish (2)? (handling indexed views, filtered indexes, foreign keys and so on)


I've looked into the ones from Haida and Nisi which are both suitable, though they're quite pricey for me currently - does anybody know of any cheaper possible alternatives? I understand there's the 160mm specifically made for use with this lens, though obtaining filters for it is difficult and limited. I'm hoping for something which may be cheaper than both Haida and Nisi, and still suitable for the 14mm lens. Thanks!

Will this  work with a ? Which adapter ring would I need to buy for it? Thank you, and apologies if any of this comes across as confusing - I'm very new to filters and what-not. I posted on another account yesterday and received some very useful tips, but had to remove it as it was a duplicate account causing me login issues. Thanks, guys!


The duplicate question above is different from this question, is I need to boolean the text from a cilinder. And that requires converting it to a mesh, which messes up the text in similar matter shown below.  I want to do the following, but it doesn't yield nice results:   Create some text Add Modifier "Curve" ALT + C -> "Mesh from curve" Give it some dimension: Add modifier "Solidify"   Then the result looks like this:   See especially the 'e'. I want to use this curved text to cut out the text from a cilinder. But that will never work propery as the letters are already messed up. Without curving they look fine, but I want it curved.  I must be possible to have nice curved 3D text in blender! How can I achieve this? I finally want to print  Thanks!

What's the simplest way to wrap extruded text around a cylinder that has a specific radius (for example, the label on a can of baked beans)?  I've tried using the Simple Deform modifier, but that (a) doesn't allow you to choose a radius and (b) requires the text to be converted to a curve.  I'm trying to model a cylinder with radius of 30, which has a line of embossed text that runs around the curved side, facing outward.  Thanks!


Is there any way to find out top 10 most used commands in history? Here top 10 means commands which I have used most of the time i.e. the commands whose used count is more than others.

How can I make a list with most used commands in terminal?  I know that this question may be unuseful for any future proposals for some of us, but even like this, the list can be useful when we don't remember a command used once or some times in the past, when we can search at the end of this list.


In some textbooks, I have seen the authors treat differentials such as $dx$ as a difference, so $dx$ = $x_2$ - $x_1$  My question is, how legal is this? I realize the differential is a quantity smaller than any conceivable real number but shouldn't this be $dx$ $\approx$ $x_2$ - $x_1$?

In my Calculus class, my math teacher said that differentials such as $dx$ are not numbers, and should not be treated as such.  In my physics class, it seems like we treat differentials exactly like numbers, and my physics teacher even said that they are in essence very small numbers.   Can someone give me an explanation which satisfies both classes, or do I just have to accept that the differentials are treated differently in different courses?  P.S. I took Calculus 2 so please try to keep the answers around that level.  P.S.S. Feel free to edit the tags if you think it is appropriate.


I'm a newbie Ubuntu user. Every time I log in to my OS, I always add:  xhost +si:localuser:root   How can I add Xhost to root permanently?  My kernel version is 4.13.0-46-generic.  I have tried , to edit something in /etc/pam.d/..., but this doesn't work for me.

I installed Ubuntu 17.10. Now I am having trouble with gksu:  $ gksu -dg synaptic No ask_pass set, using default! xauth: /tmp/libgksu-HgUjgQ/.Xauthority STARTUP_ID: gksu/synaptic/8760-0-alex-XPS-15-9530_TIME4974977 cmd[0]: /usr/bin/sudo cmd[1]: -H cmd[2]: -S cmd[3]: -p cmd[4]: GNOME_SUDO_PASS cmd[5]: -u cmd[6]: root cmd[7]: -- cmd[8]: synaptic buffer: -GNOME_SUDO_PASS- brute force GNOME_SUDO_PASS ended... Yeah, we're in... Unable to init server: Could not connect: Connection refused (synaptic:8767): Gtk-WARNING **: cannot open display: :1 xauth: /tmp/libgksu-HgUjgQ/.Xauthority xauth_env: (null) dir: /tmp/libgksu-HgUjgQ   If I don't use -g, the password dialog is disabled. So looks like a problem with creating a tty for root.  Any advice?


For a time series object (in terms of theory/concepts), do we have to have the data for each date? In some cases the customers do not make purchases/sales amounts during the same month. For example, I want to predict the sales for each customer based on their dates. I am missing some dates for sales, would this be a problem for prediction? The data below:  > amount <- c(10,11, 50, 12,30) > dates <- as.Date(c("2012-01-01", "2012-02-01", "2012-05-15", "2012-08-15", "2012-12-10")) > data <- data.frame(amount , dates) > data   amount      dates 1     10 2012-01-01 2     11 2012-02-01 3     50 2012-05-15 4     12 2012-08-15 5     30 2012-12-10  > ts(data)   We can see that row 1 and 2 are consecutive, however 3rd, 4th, 6th, 7th, 9th, 10th, and 11th month are missing. Would this be a problem?   Thanks!

I tried a forecasting method and want to check if my method is correct or not.  My study is comparing different kinds of mutual funds. I want to use the GCC index as a benchmark for one of them but the problem is that the GCC index stopped in September 2011 and my study is from January 2003 to July 2014. Thus, I tried to use another index, the MSCI index, to make a linear regression, but the problem is that the MSCI index is missing data from September 2010.   To get around this, I did the following. Are these steps valid?    The MSCI index is missing data for September 2010 through July 2012. I "provided" it by applying moving averages for five observations. Is this approach valid? If so, how many observations should I use?  After estimating the missing data, I performed a regression on the GCC index (as dependent variable) versus the MSCI index (as independent variable) for the mutually available period (from January 2007 to September 2011), then corrected the model from all problems. For each month, I replace the x by the data from the MSCI index for the rest period. Is this valid?   Below are the data in Comma-Separated-Values format containing the years by rows and the months by columns. The data are also available through this  .  Series GCC:  ,Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec 2002,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,117.709 2003,120.176,117.983,120.913,134.036,145.829,143.108,149.712,156.997,162.158,158.526,166.42,180.306 2004,185.367,185.604,200.433,218.923,226.493,230.492,249.953,262.295,275.088,295.005,328.197,336.817 2005,346.721,363.919,423.232,492.508,519.074,605.804,581.975,676.021,692.077,761.837,863.65,844.865 2006,947.402,993.004,909.894,732.646,598.877,686.258,634.835,658.295,672.233,677.234,491.163,488.911 2007,440.237,486.828,456.164,452.141,495.19,473.926,492.782,525.295,519.081,575.744,599.984,668.192 2008,626.203,681.292,616.841,676.242,657.467,654.66,635.478,603.639,527.326,396.904,338.696,308.085 2009,279.706,252.054,272.082,314.367,340.354,325.99,326.46,327.053,354.192,339.035,329.668,318.267 2010,309.847,321.98,345.594,335.045,311.363,299.555,310.802,306.523,315.496,324.153,323.256,334.802 2011,331.133,311.292,323.08,327.105,320.258,312.749,305.073,297.087,298.671,NA,NA,NA   Series MSCI:  ,Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec 2007,NA,NA,NA,NA,1000,958.645,1016.085,1049.468,1033.775,1118.854,1142.347,1298.223 2008,1197.656,1282.557,1164.874,1248.42,1227.061,1221.049,1161.246,1112.582,929.379,680.086,516.511,521.127 2009,487.562,450.331,478.255,560.667,605.143,598.611,609.559,615.73,662.891,655.639,628.404,602.14 2010,601.1,622.624,661.875,644.751,588.526,587.4,615.008,606.133,NA,NA,NA,NA 2011,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA 2012,NA,NA,NA,NA,NA,NA,NA,609.51,598.428,595.622,582.905,599.447 2013,627.561,619.581,636.284,632.099,651.995,651.39,687.194,676.76,694.575,704.806,727.625,739.842 2014,759.036,787.057,817.067,824.313,857.055,805.31,873.619,NA,NA,NA,NA,NA


I have a reusable ship in orbit and wish to add some parts to it (e.g. parachutes, heat shield, Mono-Fuel ...).  Is it possible?   Is there a mod that lets an engineer to do it?

I have a few satellites and stations orbiting my planets, but I'd like to add onto them. I've seen numerous videos on using docking clamps to attach my new ship to the existing station, but can I do that on a part-by-part basis? For example, I take an extra fuel tank up there, can I attach just the tank to my station, then send my vessel back to Kerbin? I'm not talking about refueling, but rather transferring individual parts from my ship to the station in orbit.  I'd prefer to not have to use an unmanned probe and jettison everything but the desired part in space after docking if possible, but if that's the only way I guess I don't have a choice.


Following the  thread on meta.tex.sx, it's clear that the spoiler markup has a wrinkle or two that I didn't at first appreciate.  For information's sake, the spoiler feature is contentious because it collides with the syntax for Latex errors.  Is there a precise description of when a blockquote will be treated as a spoiler?  Two related threads containing some information on the syntax:

Use cases:   Programming puzzles. This way the answer can be posted the same time as the question, eliminating doubt that no answer is possible for hard questions and proving that the question is not a homework exercise (since the author already has the answer) The socratic method. In your answer you can ask a leading question, and then once the reader has a guess they can click to reveal the answer.     EDIT: now that several new websites have been created through SE 2.0, this became much more important.  Websites such as  really need it.


I installed Ubuntu onto my hard drive (from this website), then I transferred it onto my USB flash drive.  When I try to boot it up it doesn't show up on my screen. What am I missing?

This is the third time I've tried to install Ubuntu Server 14.04.03 64-bit on the same laptop, and each time it caused different problems.  Each time I wrote the same iso image to a USB flash drive by using a different application and OS.   Universal USB Installer (pendrivelinux.com) from Windows WinImage writer from Windows built-in image writer from Linux Mint 17.2    The iso image is the same in all three cases, the USB flash drive is the same, and the laptop is the same. However each time the installation of Ubuntu gave me different installation options. For example, the last time I installed Ubuntu, it didn't show all the packages to choose while installing (Basic Ubuntu server, etc.).


Evaluate the sum $$\sum_{k=0}^{\infty} \left ( \frac{2^k}{3^{2^k}+1} \right )$$  I first tried to see weather the sum actually converges, by ratio test it does as $\lim_{n\to \infty}|\frac{a_{n+1}}{a_n}|<1$ where $a_n$ is the nth term. Now I am left with finding the actual sum. I thought to write it so that it can telescope, but can't find any suitable representations. Any hints for the evaluation part? Any Taylor polynomials etc?  Update: Wolfram says its $1/2$


Just wondering how one could visualise a curvature in spacetime. If anyone has a site, image or video showing this it would be appreciated.

With only a limited knowledge of , I usually explain space-time curvature (to myself and others) thus:  "If you throw a ball, it will move along a parabola. Initially its vertical speed will be high, then it will slow down, and then speed up again as it approaches the ground.  "In reality, the ball in moving in a straight line at constant velocity, but the space-time curvature created by the Earth's gravitation makes it appear as if the ball is moving in a curved line at varying velocity. Thus the curvature of space-time is very much visible."  Is this an accurate description, or is it complete     nonsense?


I need to get from Paris Beauvais Tille Airport to Paris center. What are my options (times, prices)?  I'll be travelling as two (or three) adults plus two small kids, therefore comfortable options are most important and speed (time) is little more imporant to me than price.

Paris has 3 airports (Orly, Roissy, Beauvais), what are the options to go to or to come from there?  (There is also Vatry (XCR) but there is very few flights and i see the shuttle system is currently off.)


I need to be able to define where a specific menu was called. Here is the basic interface:    Each line has a triangle at the end. When I click the triangle, a menu pops up, which will include a few operators that will change the action relevant to that row. The problem is, I can't figure out how to pass parameters into the menu to tell the menu "this is the action you're changing." I'm probably misunderstanding something about properties. Here's some relevant code.  class ShotsActionChange(bpy.types.Menu):     bl_idname = "SHOTS_MT_alter_action"     bl_label = "Alter action"      action_id = bpy.props.IntProperty(default=0)      def draw(self, context):         layout = self.layout         layout.label(text="This is a test!")  # ....  # row-generator loop for the panel's draw method, where this menu is called:     def action_row(self, layout, action, object=None):         iconi = self.get_data_icon(object)         obj_text = ""          if object is not None:             obj_text = object + " :: "          row = layout.row()         row.label(icon=iconi, text="")         row.label(text=obj_text + action)         row.menu("SHOTS_MT_alter_action", text="", icon="DOWNARROW_HLT")   What I want is for that last line to do something along the lines of:  row.menu("SHOTS_MT_alter_action", text="", icon="DOWNARROW_HLT").action_id = action   And that way, I can pass something into the menu. It spouts errors right now, but I don't think I know enough about the API to know whether this is impossible or just needs to be reworked. The menu itself is a hub for multiple operators, but do I need an operator that controls the opening of the menu? Any help is much appreciated.

I am trying to loop over all the cameras in my scene to populate a menu, and be able to access properties of each camera from the submenu of each menu item. For the minute, I'm just trying to get it to work with one property, the focal length:    I am able to loop over each camera and create a menu item by simply using the camera.name property in the text property of the menu item:  def draw(self, context):     layout = self.layout      for camera in bpy.data.cameras:          row = layout.row()          row.menu(CamerasSubMenu.bl_idname, text=camera.name)   However, what I don't really know how to do is make each submenu's properties relate to whichever camera I selected in the first menu. I managed to pass the camera_name to the submenu class with this in the last line of the camera loop:  CamerasSubMenu.camera_name = camera.name     And then access it with:  class CamerasSubMenu(bpy.types.Menu):     bl_label = "Camera Properties"     bl_idname = "view3d.camera_properties_menu"      camera_name = bpy.props.StringProperty()      def draw(self, context):         layout = self.layout          row = layout.row()         row.prop(bpy.data.cameras[self.camera_name], "lens")       But the lens property (the focal length) is always the focal length of whichever camera name got passed in last in the loop, e.g. 'Camera.001'. So all submenus are accessing Camera.001's focal length instead of the individual focal lengths.   I presume I'm going about this completely the wrong way, but I attempted it in a similar way I would pass data to an operator (which works).  So, is there a way to have a unique submenu per camera or should I just try something completely different?  Full code:  import bpy  class CamerasSubMenu(bpy.types.Menu):     bl_label = "Camera Properties"     bl_idname = "view3d.camera_properties_menu"      camera_name = bpy.props.StringProperty()      def draw(self, context):         layout = self.layout          row = layout.row()         row.prop(bpy.data.cameras[self.camera_name], "lens")       class CamerasMenu(bpy.types.Menu):     bl_label = "Cameras"     bl_idname = "view3d.cameras_menu"      def draw(self, context):         layout = self.layout          for camera in bpy.data.cameras:              row = layout.row()              row.menu(CamerasSubMenu.bl_idname,text=camera.name)              CamerasSubMenu.camera_name = camera.name         def register():     bpy.utils.register_module(__name__)       def unregister():     bpy.utils.unregister_module(__name__)    if __name__ == "__main__":     register()   bpy.ops.wm.call_menu(name=CamerasMenu.bl_idname)


Does any one know how can I list this remote folders mounted on nautilus?  I tried this but it doesn't seem to work:

I've setup a connectio to an FTP server in Nautilus / Nemo / Caja, the file manager. Now I can browse the contents via this file manager.  How can I browse these files via the command line? What is the path to this network connection? Is this possible, is this a system connection, or specific to the file manager, and do I have to setup a separate FTP connection to do that? If I open this connection in Caja, I see it in Nemo as well, so it seems like a system connection.


I'm using echo $(cal) and echo "$(cal)"in Linux and it gives me different results as in the picture. The double quotes should not interfere with $ in this case, so what gives the echo "$(cal)" that horizontal style comparing to echo $(cal).  This is the result:    echo "$(cal)"  Su Mo Tu We Th Fr Sa                      1    2  3  4  5  6  7  8    9 10 11 12 13 14 15   16 17 18 19 20 21 22   23 24 25 26 27 28 29   30   echo $(cal)   June 2019 Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

I used one of the following  echo $(stuff) echo `stuff`   (where stuff is e.g. pwd or date or something more complicated).  Then I was told this syntax is wrong, a bad practice, non-elegant, excessive, redundant, overly complicated, a cargo cult programming, noobish, naive etc.  But the command does work, so what exactly is wrong with it?


I get a message:     Sorry, you are only allowed to ask 50 questions in a 30 day period   Why is there a question limit? 50/month is just not enough :)

I noticed that I can only perform certain actions such as commenting a finite number of times in a given period of time. Obviously, rate limiting is in place to prevent accidental misuse or intentional abuse of certain features.  Where else is rate limiting applied on Stack Exchange sites, and what are the limits?


I link 3  figures below  .      The white bulbs were on my backside on the ceiling as is visible in their reflection in the television. I was sitting almost between (length wise) the bulbs and the television. I took the photographs of their reflection in the LCD.   What are these crosses of rainbow coloured fringes?   Is it interference or diffraction?   And whatever of the 2 it is, how is it happening?   Why only 2 crosses of coloured fringes in the reflection of every bulb , when the angle of each bulb is different?   The bulbs were on my backside so Lloyd's mirror like explanation isn't possible.   Why only 2  crosses of coloured fringes are appearing in the reflection of all the bulbs when they are at different angles?   How is this being caused?   I don't know whether stack exchange is the right place to ask this question by uploading the pictures related to the question , but I couldn't find anyone who could give a reasoning and so I posted it here.   Ever more interesting is that the reflection of the CFL visible in 1st and 2nd pictures is not showing any such pattern.

I was up late working with my red LED headlamp on and when I was looking at the black part of my LCD (Apple Retina Macbook Pro) screen I noticed this interesting diffraction pattern. I'm confused because all I can think of that would cause this are Fourier and Fraunhofer patterns which I thought required more advanced optics the light to be collimated. One friend suggested it might be the polarizer. Any thoughts?  Unfortunately, the picture doesn't show this, but along the x and y axes there were discrete points not a continuous streak. Sorry for the horrible photo quality.


Is there a rule for good usage as concerns applying a number word as "one", "two" and so on as opposed to Arabic numerals as "1342"? Is it, for instance, a rule that numbers less than 20 should be designated with number words and larger numbers with Arabic numerals?

The junction has a stop sign on each of the four entrances.   The junction has a stop sign on each of the 4 entrances.   The first is preferred, for some reason, by many English texts. Why? I haven't seen this phenomenon in other languages.


I would like to prove it using Euler's Theorem, which states that if $\gcd(a,n)=1$,then $a^{\phi(n)}=1 \pmod{n}$. Then, $480$ should be factored, but I am unsure how to proceed with the proof. Thanks in advance.

I am trying to show that $a^{12} \equiv 1 \mod 32760$ for each $a \in \mathbb{Z}$ coprime to $32760$. I have found the prime decomposition $32760 = 2^3 \cdot 3^3 \cdot 5 \cdot 7 \cdot 13$ and determined $\phi(32760)$, where $\phi$ is the Euler's totient function. This gives me that $\phi (32760) = 8640$.   Using Euler's congruence, this gives that $a^{8640} \equiv 1 \mod 32760$, but this is still far from the result I want to show... I also know a consequence of Eulers congruence, which states that $e \equiv e' \mod \phi (n)$ implies that $a^e \equiv a^{e'} \mod n$, but I do not see how to use this...  Any hints would be appreciated.  $\textbf{EDIT:}$ I made a mistake in my primefactorization, it is edited now.


Sometimes I come across some texts with a few mistakes in typing, something like 2 or 3 characters, that I can't correct, specially because is mandatory to fix at least 6 characters and I don't want to add more content to arrive at the missing characters. What I can do to fix the content ? There is not a mistyped edit mode?

Possible Duplicate:          Occasionally I come accross a post like , where    the lack of code formatting is a significant problem the post is so deliberately simple that further changes disrespect the original author's intent.     How should I attempt to improve such posts, given the 6 non-space character limitation?  Submit an overzealous edit and assume it will be pared down if necessary?  Give up and come back when I hit 2k?


I'm trying to install Apache into Ubuntu Desktop 18.04.1, but retrieving the error: package apache2 has no installation candidate Any help, please? Thanks!

There are now errors when updating and I cannot install most software due to a corrupted  /etc/apt/sources.list   file. Is there a copy I can download to replace it?  The file would be for Ubuntu 12.04 (Final Beta) in the United States.


Using only awk, how would you convert the following text from this: $ cat latest.csv psga,alp1acscf0001vm001oam001p1n004v001,192.7.129.7,UVP apsga,alp1acscf0001vm001oam001p1n004v002,192.7.129.8,UVP apsga,alp1acscf0001vm002oam001p1n004v001,192.7.129.9,UVP apsga,alp1acscf0001vm003oam001p1n004v001,192.7.129.10,UVP apsga,alp1acscf0001vm004cif001p1n004v001,192.7.129.11,UVP apsga,alp1acscf0001vm004cif001p1n004v002,192.7.129.12,UVP apsga,alp1acscf0001vm005cif001p1n004v001,192.7.129.13,UVP  I managed to get the following output: $ awk -F','  '{ print substr($2, 1, 14),  (substr($2, 1, 18)),$3 }' latest.csv alp1acscf0001v alp1acscf0001vm001 192.7.129.7 alp1acscf0001v alp1acscf0001vm001 192.7.129.8 alp1acscf0001v alp1acscf0001vm002 192.7.129.9 alp1acscf0001v alp1acscf0001vm003 192.7.129.10 alp1acscf0001v alp1acscf0001vm004 192.7.129.11 alp1acscf0001v alp1acscf0001vm004 192.7.129.12 alp1acscf0001v alp1acscf0001vm005 192.7.129.13  However, I would like the first substr($2, 1, 14) only once at the beginning of the line and the remainder in a single line as below: alp1acscf0001v alp1acscf0001vm001 192.7.129.7 alp1acscf0001vm001 192.7.129.8 alp1acscf0001vm002 192.7.129.9 alp1acscf0001vm003 192.7.129.10 alp1acscf0001vm004 192.7.129.11 alp1acscf0001vm004 192.7.129.12 alp1acscf0001vm005 192.7.129.13

Good day. Using only Linux OS tools, how would you convert the following text from this: cat latest.csv apsga,alp1acscf0001vm001oam001p1n004v001,192.7.129.7,UVP apsga,alp1acscf0001vm001oam001p1n004v002,192.7.129.8,UVP apsga,alp1acscf0001vm002oam001p1n004v001,192.7.129.9,UVP apsga,alp1acscf0001vm003oam001p1n004v001,192.7.129.10,UVP apsga,alp1acscf0001vm004cif001p1n004v001,192.7.129.11,UVP apsga,alp1acscf0001vm004cif001p1n004v002,192.7.129.12,UVP apsga,alp1acscf0001vm005cif001p1n004v001,192.7.129.13,UVP  I managed to get the following result: cat latest.csv`|awk -F',' '{print $2, $3}'|awk '{ $1 = substr($1,1,21); print $1","$2}' alp1acscf0001vm001oam,192.7.129.7 alp1acscf0001vm001oam,192.7.129.8 alp1acscf0001vm002oam,192.7.129.9 alp1acscf0001vm003oam,192.7.129.10 alp1acscf0001vm004cif,192.7.129.11 alp1acscf0001vm004cif,192.7.129.12 alp1acscf0001vm005cif,192.7.129.13  I would like the end result to look like this: ALP1A/alp1acscf0001v,UUID,192.7.129.7,SSH2,alp1acscf0001vm001oam ALP1A/alp1acscf0001v,UUID,192.7.129.8,SSH2,alp1acscf0001vm001oam ALP1A/alp1acscf0001v,UUID,192.7.129.9,SSH2,alp1acscf0001vm002oam ALP1A/alp1acscf0001v,UUID,192.7.129.10,SSH2,alp1acscf0001vm003oam ALP1A/alp1acscf0001v,UUID,192.7.129.11,SSH2,alp1acscf0001vm004cif ALP1A/alp1acscf0001v,UUID,192.7.129.12,SSH2,alp1acscf0001vm004cif ALP1A/alp1acscf0001v,UUID,192.7.129.13,SSH2,alp1acscf0001vm005cif  Thanks in advance, Bjoern


This is a rather bizarre problem that I am experiencing. My Ubuntu 14.10 does not let me log in despite proper password. Here is what happens:    I try to log into my machine by entering the password. The password gets accepted, my laptop screen blinks, and brings me back to the login screen.     After having tried this many times I tried Guest Session. When I click on login in guest session, the same story repeats itself.    The only thing different from yesterday (when I could properly log in) is that I installed virtual box and Genymotion for Android development. Also, I made a simple change to /etc/profile to have genymotion in my path.  How do I solve this?

My Ubuntu is stuck in a login loop when trying to enter my desktop. When I login, the screen gets black and soon after that the login screen comes back.   I've read that the problem might be caused by an error depending on the graphics, here's my graphics card: ATI Radeon 7670M


So I had a dual boot Linux and windows 10 and I just wanted to go back to windows 10 so me being absolutely dumb just goes ok and deleted the Linux boot and now I get a grub error I just want to go back to windows 10 but I don’t want to reinstall anything

After I deleted my Ubuntu partition, I rebooted my computer and I only get a prompt:   grub rescue >   The command ls lists   (hd0) (hd0,msdos5) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1) (hd1) (hd1,msdos1)   I check them one by one:  ls (hd0,msdos5)/ ls (hd0,msdos1)/   But I cannot find the right partition.


Should I buy/purchase web hosting?   Should I buy/purchase Adobe Photoshop?   Should I buy/purchase this car?   Should I buy/purchase this land?      When should I use buy and purchase? Why?

When we use the word "to buy" and when the word "to purchase"? I do not understand the difference between these words.


I am  sure that it holds for ordered sets but in the case of unordered set such as $$A={(1,2,3)}, B={(5,1,4)}$$ it does not hold. As $A+B$ will be ${(6,3,7)}$.    $\inf(A+B)=3$ $$\inf(A)+\inf(B)=1+1=2$$

If $A,B$ non empty, upper bounded sets and $A+B=\{a+b\mid a\in A, b\in B\}$, how can I prove that $\sup(A+B)=\sup A+\sup B$?


It seems to me that's very tricky to get people engaged in a SE site outside of the one they initially joined. One incentive might be to introduce network-wide badges.   These might include, for example:   Having over 1000 reputation on 5+ SE sites Have a question with 5+ upvotes on 5+ SE sites Have an answer with 10+ upvotes on 5+ SE sites etc.   I'd personally like to see this, but I think it might be good for SE as a whole, too.

It might be useful to encourage existing users of stackoverflow to cross pollinate other stack exchange sites.  While rep-sharing is not useful, as rep is meant to be a measure of expertise in one subject, badges may be one way to encourage participation across many sites.  This was triggered by seeing how few people actually had greater than 1k rep on all three main sites (SO, SF, SU) via Dennis Williamson's  app.  I had tried to do this by hand prior to the API under the assumption that many people would be answering questions on all three sites, but it turns out there are only 33 people, of all the users of stackoverflow, that have a 1k+ reputation on all three sites.  Over time it may be useful to provide badges that appear on all sites one is participating in that are awarded for extraordinary participation in the whole universe of Stack Exchange sites.  For instance, a silver badge might appear on all my profiles if I obtain 1k rep on 5 or more sites, and a gold badge if I have more than 3k rep on 5 or more sites.  I would hesitate extending this much past 5 sites as we don't want to encourage spamming questions and answers on sites where the user has little interest, but across the universe of stackapps I know I'm proficient or expert in at least 10 current sites, and while it's not a big nudge, the idea that I can get extra awards - especially ones that appear on all sites I'm in - would move me to participate a little more on sites that I am registered on, but don't visit regularly.    I expect, eventually as sites are launched, most users of any one site will have some interest or knowledge in at least 5 other sites.  This may provide the extra nudge some sites need to maintain an excellent rating in terms of usage.


(Using Principled BDSF)   I'm aware that glasses are naturally going to have a bit of black anyway, and I have no problem with the black sections around the base of the main section and the beginning of the handles, but the rim just can't be correct, can it? It started out from following the BlenderGuru tutorial, but his looks nothing like what I ended up with.  If you look at the .blend and image you'll see there is definitely a problem there (at least I hope so - I'd rather a fixable problem than a generally incorrect model/scene). Rotating around shows that, even when the rim has only 2 layers opposed to 4 for the light to pass through, the problem is always there on the rim. Thickness of the glass and how many layers it passes through is not what is affecting the rim. Those 2 things do affect the base/handles, but I'm happy with that.  I have tried adjusting geometry and applied the first layer of Subsurf as other posts said to - no change.   I tried adjusting the bounce levels on light paths, under both Path and Branched Path Tracing - caustics and transmissions etc etc - but nothing seemed to happen.   I added an HDRI in case lighting was an issue, but again, no change in the rim.  The only thing that seemed to do anything is applying a Solidify modifier at a very low thickness above Subsurf in the stack, but this surely isn't the correct solution and the IOR seems off to me after doing so. I have already applied thickness to the model anyway, so it's not like I have a paper-thin glass.

My model has a clear plastic (or glass) dome with objects inside.  The objects appear dark.  I've tried the glass shader with color 100% RGB, with very small IOR, and using just a refraction shader.    I know Cycles has problems with caustics, but I just want broad illumination to fall clean through the glass.  The light-to-column path can ignore refraction, but is blocked or tremendously attenuated. The camera-column path needs refraction, and seems to work fine anyway.  This demo image offers all optical paths of interest:   light upon object, seen directly light upon object, seen through glass (looks okay) light through glass onto object, seen directly. This is the shadow on the lit side of the column just below the glass tubing.  I expect full illumination, but there is shadow.  There is some light, but it's diffuse light from the floor. light through glass onto object, seen through glass. This     I did at one point try non-progressive rendering, and find extremely coarse light where there shouldn't be shadow, but this is not a practical way to make nice images. I've even tried cranking up certain sampling settings to many thousands, but still get bad noise though less, at the cost of long render times. I  would like to finish my creations sometime before "Star Trek, the Generation After the Next" becomes real life, if you know what I mean.  The next image is an example. I think Transmission in Sampling was 5000, but not sure.    I'm using Cycles in Blender 2.67 on a quad core Linux machine, 16GB RAM. Machine limits have never been a problem for 3D rendering.  Possibly, I screwed up some setting when I made my startup file, and just need to fix it. OTOH maybe this is just a limitation of path tracing, or of the way Cycles does it. If that's the case, what to real-world Blender artists do when they need to produce images on a budget and schedule?  What is the practical real-world fix?


when user runs the application twice or more in the system tray number of running same application increases , this creates parallely multiply running on same application how to handle this?   Here is the picture to understand what I am talking about:

Sometime I see many application such as msn, windows media player etc that are single instance applications (when user executes while application is running a new application instance will not created).  In C#, I use Mutex class for this but I don't know how to do this in Java.


For a long time, each vote for a question gave you only 5 rep because if you have a question, do no research on it, then put it on a Stack Exchange site (especially Stack Overflow) and it's a popularly asked question, it will get hundreds of upvotes.  Look at the top voted questions on Stack Exchange, they have no research and very little content – most of them are one or two sentences – but the hundreds of people who look up the same question see the answer, think "Oh, that's useful", then upvote it. And if you have a question about a somewhat obscure topic, put a lot of research and time into it, it will get very few upvotes.  Why?  Because it's not a popular question.  All of the popular questions are taken, so there's nothing you can do.  Users can get a lot of non-deserved reputation that way. The very text of the upvote button says, "This question shows research effort; it is useful and clear", but that's not the reason why people upvote the top questions. The question is, what can be done about it?  For a time there was awarding of only half-reputation for question upvotes but that's not fair to those who actually have good questions.  And forcing people to put a lot of text into the question body will just be a frustrating annoyance. Are there any solutions to this?

Why do some very simple questions get lots of upvotes while some of the really logical questions get very few upvotes?  On Stack Overflow I have seen dozens of simple questions (whose answers are easily available on the Internet) get many upvotes, while some very logical questions sometimes only get one or two upvotes. What should we do?


I'm looking for a fantasy novel, pre-2000. It's young adult fantasy.   Magical abilities involved talents similar to psychic abilities. One character could hide the group, preventing others from seeing them. One character could start fires. They were on some sort of quest and had to go into the enemy territory.   Argh! It's so frustrating. I can't remember much about the book, but would recognise it instantly.  It's not Xanth and not Julian May. It's sort of a Stephen King's Firestarter meets Andre Norton type novel.

This is a book I read as a child, so sometime in the 1980's  . It was actually a two part book series, both normal novel length. It was a swords and sorcery style setting.  Details are sketchy, but I'll give you what I can remember.  It centred around  a boy on a quest against some demon-like villain wizard type character. At some stage a girl was kidnapped and they were off to rescue her ( fairly generic stuff)  . I think the girl also had magic powers, healing I think.  This boy could control the weather or elements. He encounters a monk type character who ends up travelling with him and becomes a teacher of sorts. This monk is actually blind, but can still sense his surroundings, DareDevil style. ( I cannot remember if this was a magical ability or just something the monk had developed over time. ). I seem to remember this character had black, reptilian style eyes.  There may have been more people travelling with them I don't recall.  I recall the encounter with the main enemy took place on the top of a mountain, this mountain had the top taken off so was perfectly flat. ( I hope I'm not getting muddled with a different book with this detail)  The baddie know the boy could only control the elements if he was exposed to them, so ended up sealing the room he was fighting in so the boy had no contact with the outside. He won through by using a dagger or sword to make a crack in the floor through the protection, giving him enough of a connection with the outside to use his powers. I /think/ he died during this battle, and the girl they were rescuing brought him back to life. ( Or maybe she dies, and was brought back to life somehow)


In our 6th grade math class we got introduced to the concept of integers. With all the talk about positive and negative, it got me wondering. Is the amount of elements in $\mathbb{Z^+}$ less than the amount of elements in $\mathbb{Z}$?  Here is how I thought of it. If we have $\mathbb{Z^+}$ and add one element to the "back" of it ($\mathbb{Z}^{\geq-1}$) there are certainly more elements in that new set, so there must be more elements in $\mathbb{Z}$ than in $\mathbb{Z}^+$ but on the other side if we try to express the amount of elements in them "numerically" (In a loose sense of the word) they both have $\infty$ elements.    So what is the right answer? Is there even one?  (Please note I am a bit of a layman when it comes to mathematics)  Edit: About the possible duplicate, I am not looking for a bijection between the two sets, I am looking for if they even have the same number of elements and why a bijection shows that they do/don't

How would I show the following have a bijection. Which is one to one and onto ofcourse.  $\mathbb{Z}\rightarrow \mathbb{N}$  I know I need to find a function. But I do not see the pattern that makes integer go to natural. I already did this problem from natural to integer but now I want to see it done this way.  I have listed some numbers  $,..,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,..$  $1,2,3,4,5,6,7,8,9,10,11,12,13,14,.$


HDD; debian OS; orangepi; 2TB; (SCSI DISK) (WDC WD20 03FZEX-00SRLAO)  ......................  I am trying to mount my 2TB WD hdd. as "mount rw, /dev/sda1 exthdd; mount -o rw /dev/sda1 /media. lsblk: disk recognized. DMESG | TAIL : couldn't mount RDWR b/c of unsupported optional features (400)  "Failed to mount "exthdd". Error mounting /dev/sda1 at media/username/exthdd: command line 'mount -t "ext4" -o uhelper=udisks 2,no dev,nosuid "/dev/sda1" "media/username/exthdd - exited with non-zero exit status32: ; "mount: wrong fstype, bad options, etc etc etc........other"  *****After reading the 'similar' article, I tried the following:  "turn it off on an already created filesystem" "sudo tune2fs -O ^metadata_csum /dev/sdb1"  Did not work. The aforementioned article talks about an SD CARD, my media is a hdd.  Not able to mount either "ro,noexec" or "rw" on my desktop computer where the hdd was formatted. I was able to mount it to a laptop w/ ubuntu, but was not able to copy, paste, or create a folder as "permission denied". I think this hdd was specifically formatted to be solely used with my username for this desktop, debian OS, computer.  I see to format external media, do the following... You'll see where it says "chown" that it asks for my username. I'm wondering if I can do something to remove my username from the hdd (if it's on there) so it will work on other systems.....??????  Thanks.

I try to run Android from SD-card. This card is prepared. There are partitions: boot(FAT32), rootfs(ext4), system(ext4), cache(ext4) and usedata(ext4). Boot partitions has files to run u-boot: MLO, u-boot.bin and uImage. To run it I use commands  mmcinit 0 fatload mmc 0 0x80000000 uImage setenv bootargs 'console=ttyO2,115200n8 mem=456M@0x80000000 mem=512M@0xA0000000 init=/init vram=10M omapfb.vram=0:4M androidboot.console=ttyO2 root=/dev/mmcblk1p2 rw rootwait rootfstype=ext4' bootm 0x80000000   Than I see how Linux starts. But after few seconds on step of loading rootfs I see an error message  [    4.015655] EXT4-fs (mmcblk1p2): couldn't mount RDWR because of unsupported optional features (400) [    4.036499] sd 0:0:0:0: [sda] Attached SCSI removable disk [    4.079986] List of all partitions: [    4.083801] b300        31162368 mmcblk0  driver: mmcblk [    4.089660]   b301             128 mmcblk0p1 f9f21f00-a8d4-5f0e-9746-594869aec34e [    4.097839]   b302             256 mmcblk0p2 f9f21f01-a8d4-5f0e-9746-594869aec34e [    4.106018]   b303             128 mmcblk0p3 f9f21f02-a8d4-5f0e-9746-594869aec34e [    4.114288]   b304           16384 mmcblk0p4 f9f21f03-a8d4-5f0e-9746-594869aec34e [    4.122436]   b305              16 mmcblk0p5 f9f21f04-a8d4-5f0e-9746-594869aec34e [    4.130676]   b306            8192 mmcblk0p6 f9f21f05-a8d4-5f0e-9746-594869aec34e [    4.138916]   b307            8192 mmcblk0p7 f9f21f06-a8d4-5f0e-9746-594869aec34e [    4.147094]   103:00000     524288 mmcblk0p8 f9f21f07-a8d4-5f0e-9746-594869aec34e [    4.155334]   103:00001     262144 mmcblk0p9 f9f21f08-a8d4-5f0e-9746-594869aec34e [    4.163574]   103:00002   30342128 mmcblk0p10 f9f21f09-a8d4-5f0e-9746-594869aec34e [    4.171874] b310            2048 mmcblk0boot1  (driver?) [    4.177734] b308            2048 mmcblk0boot0  (driver?) [    4.183593] b318        15179776 mmcblk1  driver: mmcblk [    4.189453]   b319          102400 mmcblk1p1 00000000-0000-0000-0000-000000000000 [    4.197692]   b31a           10240 mmcblk1p2 00000000-0000-0000-0000-000000000000 [    4.205932]   b31b               1 mmcblk1p3 00000000-0000-0000-0000-000000000000 [    4.214141]   b31d          262144 mmcblk1p5 00000000-0000-0000-0000-000000000000 [    4.222351]   b31e        13228032 mmcblk1p6 00000000-0000-0000-0000-000000000000 [    4.230682]   b31f         1572864 mmcblk1p7 00000000-0000-0000-0000-000000000000 [    4.238891] No filesystem could mount root, tried:  ext4 [    4.244812] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,26) [    4.254089] CPU1: stopping   I don't know why it happens.  How can I solve this problem?


I'm trying to find out if using "limit 1" would work faster while executing a "select" query on MySQL database with milions of records, like:  SELECT * FROM users where id = 99999;  SELECT * FROM users where id = 99999 LIMIT 1; /* Is it faster? */   I made some tests executing some queries with and without the LIMIT, but the difference between them are really small (using LIMIt has some better speed tho), but I'm not sure if there is any difference between using the "WHERE" in a not indexed column and in an indexed column, if it would have some performance problem or not.  Should I use the "LIMIT 1" in all queries that I want to return only one result even knowing that the "WHERE id = 99999" will return only one row?

When I add LIMIT 1 to a MySQL query, does it stop the search after it finds 1 result (thus making it faster) or does it still fetch all of the results and truncate at the end?


I read somewhere that removing .pdb file cause increase in performance of the program. What are the cons and pros of removing these files?

I am deploying ASP.NET and Web Service solutions to IIS for a development server. It looks like the last person that did this job deployed all the .pdb files too. I asked about it, and was told that they "provide better stack trace info in the logs" if they are left on the server.  Is there any truth to this? I've always left them behind, never deploying them to anywhere other than my local machine.  For an internal development IIS server (not production, not accessible to the outside world) is there any reason to or not to deploy the .pdb files? Is there anything bad that could happen? Do they really provide any benefit?


I want to add a list (a) to another list (b). But with the twist, that I can change list a and the added list a in list b stays as it was. So that I can add list a again.  for example:  a = [a, b , c] b = [1, 2] b.append(a)   now b is [1, 2, a, b, c]  a = [4, 3]   and now b should stay [1, 2, a, b, c] so that I could append b again by a so, that it would be [1, 2, a, b, c, 4, 3]  So I try to create a list b, that is like an overview of the whole thing and need the list a, that I added earlier to stay the same in list b while I change it in the second run through the for loop.   (I am still kinda new to python and stack overflow so sorry for any mistakes xd)  Edit: I saw, that this question got linked to similar one, but the key difference (at least in my eyes) is, that I don't want to mutplicate the same thing, but to add a list (a) to another list (b) and being able to change a. At the same though the a in b should stay the same.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I have quite a simple question. Energy can be defined as capacity to do work.   But I have read     When energy is exchanged between thermodynamic systems by thermal interaction, the transfer of energy is called heat.   I can't understand what is the work done. For example, what is the work done in cooling water from 20 to 40 celsius (1 atm)?   So, is heat a form of energy if energy is capacity to do work?

Is it energy?  Is it energy per unit volume?  Is it energy per unit time i.e power?  What is it?


My USB's 16 GB, but I only get to use 4 GB in persistence file. Any way to increase it?

I want to make a persistent live Ubuntu USB drive with more than 4GB of storage.   I know there is an option of installing directly on the drive but I don't want to do this as it will restrict the drive from working on different computers.   One option is to make an additional partition with extra space but if I do this how can I get newly installed software to be stored on this partition?


I want to shoot amazing portraits like the ones I see in magazines or model shots. Can it be done with my  EF-S 18-55mm IS 2? If not, please give names of affordable cheap lenses I can buy for this.

I have a Canon T2I, and also a good prime lens (50mm / f1.8) but I cannot seem to take close up portraits like I see in magazines. Do I need a better lens?


What I'm doing wrong here? Why is the gear like reseting its rotation?   (Gif too heavy to upload here)

I'm try to rig a low poly clock for blender, so I added a copy rotation constraint so the minute hand would automatically spin with the second hand, but when I rotate the second hand 180 degrees, the minute hand reverses its rotation.


Getting "main" java.lang.NullPointerException in Selenium  I am new to Selenium and I have started POM structure by following Youtube/Udemy tutorials. Iam getting this error.  My POM class code :  package Pages; import org.openqa.selenium.WebDriver; import org.openqa.selenium.chrome.ChromeDriver;  public class Guru99Homepage {     WebDriver driver;      public Guru99Homepage(WebDriver driver) {         this.driver = driver;     }      public void browserlaunch() {         System.setProperty("webdriver.chrome.driver", "/Users/saurabh.gupta/eclipse-workspace/Project/Driver/chromedriver");         driver = new ChromeDriver();     }      public void openguruwebsite() {         driver.get("http://demo.guru99.com/V4");     }  }   2nd POM Class :  package Pages; import org.openqa.selenium.By; import org.openqa.selenium.WebDriver;  public class Guru99LoginPage {     WebDriver driver;      public Guru99LoginPage(WebDriver driver) {         this.driver = driver;     }      public void username(String User_name) {         driver.findElement(By.xpath("//input[@name='uid']")).sendKeys(User_name);     }      public void Password(String Pass) {         driver.findElement(By.xpath("//input[@name='password']")).sendKeys(Pass);     }      public void clickat_loginbutton() {         driver.findElement(By.xpath(" //input[@name='btnLogin']")).click();     } }   Test case :  package TestCases; import org.openqa.selenium.WebDriver; import Pages.Guru99Homepage; import Pages.Guru99LoginPage;  public class Guru99Login{      public static void main(String[] args) {         WebDriver driver = null;         Guru99Homepage homepage = new Guru99Homepage(driver);         Guru99LoginPage lgnpage = new Guru99LoginPage(driver);          //Browserlaunch         homepage.browserlaunch();          //WebsiteOpen         homepage.openguruwebsite();         //driver.manage().window().maximize();         lgnpage.username("mngr47659");         lgnpage.Password("123456@");         lgnpage.clickat_loginbutton();     } }   "I am able to open browser but after that Iam getting the below error message"   INFO: Detected dialect: W3C Exception in thread "main" java.lang.NullPointerException     at TestCases.Guru99Login.main(Guru99Login.java:31)   Please help me ,so that I can start pom structure with your support.  Thanks

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied) E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?   I've done everything i could and i still get this can anyone help?

I have just booted my clean Ubuntu 18.04 LTS VM and tried to install some application with sudo apt install.  But got error message:     E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)       E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?   What process created the /var/lib/dpkg/lock-frontend file in Ubuntu? How to gently stop it and take manual control on APT?


I'm using XML to create a dynamic SQL Query. I need to use the operator IN, but I can't make it work with multiples values.  To illustrate my matter here is what does work :  exec sp_executesql N'SELECT * FROM commercial_element WHERE specific_info IN (@IncludedListB)                 ',N'@IncludedListB nvarchar(30)',@IncludedListB='BAR'   The parameter @IncludedListB is built as a string in C#  filter.IncludedListB = 'BAR';   What I am trying to do is passing multiple paramters in the operator IN :  exec sp_executesql N'SELECT * FROM commercial_element WHERE specific_info IN (@IncludedListB)                 ',N'@IncludedListB nvarchar(30)',@IncludedListB='''BAR'',''BSO'''   Building like so :  filter.IncludedListB = ''BAR','BSO'';   Focusing only on the SQL Why does my second query doesn't work ? I'll figure it out for the C#.

How do I parameterize a query containing an IN clause with a variable number of arguments, like this one?  SELECT * FROM Tags  WHERE Name IN ('ruby','rails','scruffy','rubyonrails') ORDER BY Count DESC   In this query, the number of arguments could be anywhere from 1 to 5.  I would prefer not to use a dedicated stored procedure for this (or XML), but if there is some elegant way specific to , I am open to that.


I know there are a lot of questions about this issue already - but now I have experienced it myself and I am a kind of baffled. I simply don't understand the system. There is no place other than this to raise my incomprehension issue.   Today I (also) experienced :     You have failed too many recent review audits – looks like you might   need a break. Come back in 2 days to continue reviewing.   After one apparently "wrong" audit, which I by the way didn't understand should be wrong at all. Of course I have failed audits before, once in a while, and I have made mistakes after reviewing thousands of post in all the categories. But what's making me wonder most, is why it is coming now, when I have passed all audits in the past 4 or 5 days, without a single "stop and listen"-message?   Could the moderators look into this?   I appreciate the system, and if I am wrong I am wrong. And to me a pause is good. I just do not understand why my quarantine comes now, when I actually have passed all the audits except one, and not the day where I didn't pass 5 times.   I can understand "too many", but not "too many recent".   I post this because I have read  post,  and  (to clarification) post already.

This morning I did what I usually do, which is to go through and do some reviews (close votes, mostly). I was reviewing a post in the Low Quality queue that was questionable, but I let it pass (I've seen a lot worse, but this one seemed, to me at least, to be a valid answer to the question). Immediately, I got the screen that told me that I'd failed an audit. That I'm okay with, and I fully understand.  Right after it, though, it's now giving me everyone's favorite message:     You have failed too many recent review audits – looks like you might   need a break. Come back in 2 days to continue reviewing.   I swear I haven't failed a single review audit in at least a month, maybe even longer. Why is it locking me out after failing only 1 audit?!? Is there a counter that just never resets no matter how long it is in between failing audits? That seems a little unfair...


Suppose given a exact sequence, $$0 \to A\xrightarrow{\enspace f\enspace} B\xrightarrow{\enspace g\enspace} C\to 0$$ I want to show the sequence,$\DeclareMathOperator{\Hom}{Hom}$  $$0→\Hom_R(N,A) \xrightarrow{\enspace f_*\enspace}\Hom_R(N,B)\xrightarrow{\enspace g_*\enspace} \Hom_R(N,C)$$ is also exact.  Here $f_*:\Hom_R(N,A)\to \Hom_R(N,B)$ is defined to be, $$f_*:f\mapsto h\circ f$$where $h$ is a $R$-homomorphism from $A$ to $B$.  I'm having trouble proving exactness at both points. Please help. Thanks!

If    $$ 0 \to A \to B\to C,$$    is a left exact sequence of $R$-module, then for any $R$-module $M$,    $$ 0 \to \operatorname{Hom}_R(M,A)\to \operatorname{Hom}_R(M,B)\to \operatorname{Hom}_R(M,C), $$    is left exact.   I proved the above, and highlighted what I'm a little unfamiliar with: Let $$ 0 \to A\ \xrightarrow{i}\ B\ \xrightarrow{f}\ C, $$  and  $$ 0 \to \operatorname{Hom}(M,A)\ \xrightarrow{\operatorname{Hom}(M,i)}\ \operatorname{Hom}(M,B)\ \xrightarrow{\operatorname{Hom}(M,f)}\ \operatorname{Hom}(M,C). $$  We need to show that  $$ \ker\left(\operatorname{Hom}(M,f)\right)=\operatorname{Hom}(M,i)(\operatorname{Hom}(M,A)). $$   Let $i \circ \varphi \in \operatorname{RHS}$. Then $f \circ i \circ \varphi : M \to C$ is $0$ since $f \circ i \circ \varphi(M) \subseteq f( i(A)) = f(\ker(f))=0$.  Conversely, let $\psi \in \operatorname{LHS}$. Then $f \circ \psi = 0$ so that $ f(\psi(M))=0$. Hence $\psi(M) \subseteq \ker(f)=i(A)$. Since the image of $\psi$ is contained in the image of $i$, we may factor $\psi$ as $\psi=i \varphi$ with $\varphi : M \to A$. (Here is my trial, but I'm not fully understanding this: Since $i$ is injective, $i(A)$ is isomorphic with $A$. So $i^{-1}(\psi (M)) \subseteq A$ and if we let $\varphi=i^{-1} \psi$, then $\psi = i \varphi$.)  And I have one more question: The above looks very messy, especially the notation. Is there a better proof/understanding about it?


According to my Windows Explorer, I'm running out of space on my C: drive, with only 22 GB left out 517 GB.  However, I ran  and , each of these shows that the C: drive only takes up just less than 260 GB.  Here's an image of all three of them together.    Why is so much space (~235 GB) unaccounted for, and where can I being looking for the spacing-hogging culprits?  I'm not sure what to do.

How can I visualize which folders and files are taking up all of the space on my hard drive?  I'm getting some conflicting reports on the size of hard drive contents. Namely what is and isn't there and what folders are actually using the space.   I need to know which of the files or folders the culprits behind all this hidden bloat. Also there should be a print option to get it on paper.


The Fermat numbers are defined by $F_m = 2^{2^m} + 1$.  Prove that for $m \ne n$ we have $(F_m, F_n) = 1$.  I have to first prove that $F_{m+1} = F_0F_1 \cdots F_m + 2$ by representing $F_{m+1}$ in terms of $F_m$.

I've been working with the Fermat numbers recently, but this problem has really tripped me up. If the Fermat theorem is set as $f_a=2^{2^a}+1$, then how can we say that for an integer $b<a$, the $\gcd(f_b,f_a)=1$?


Consider the following:  \documentclass{memoir} \usepackage{array} \begin{document} \begin{tabular}{l>{\raggedright}p{0.45\textwidth}}         foo   & bar  \\         one   & two  \\         three & four \\ \end{tabular} \end{document}   It gives me the following error message:  ! Extra alignment tab has been changed to \cr. <recently read> \endtemplate   l.6         one   &                     two  \\ ?    Clearly I am doing something wrong but I just can't figure it out. Can someone explain it to me?

I would like to create a table with some columns' width specified, while the text in those columns should be centered both horizontally and vertically. I found out that  \usepackage{array} \begin{tabular}{| c | c | m{5cm} |}   vertically centers the text in the last column, but justifies it horizontally (like text in normal paragraphs).  Update: With Jake's method, it seems both \\ and \hline cause an error. How to fix it?


I just graduated college in May, and I spent my entire college career convinced that I would never study again. I had a plan for my future, and it involved working- no more school. I had considered grad school, but never very seriously.   Now, however, I am very much considering a grad or PhD program. Unfortunately, because of my intentions before, I hadn't done much research in college, opting instead for leadership and work experience. I also didn't foster any significant relationships with my professors. I talked to them enough to learn the material and pass the class, but, in my opinion, not enough for a glowing recommendation.  Now, I feel like I wasted something. How can I get into grad school when I am unable to procure stellar recommendation or show that I took classes in pure, theoretical mathematics? (I took more classes that concerned mathematics applied, like statistics and practical life models and such)  Would it be necessary for me to take more classes? Go back to school? That seems unnecessary, since I already have a bachelor's degree in Math, but I don't know what I can do.

Background I was ignorant as an undergraduate and didn't focus heavily in any specific area. I finally graduated with a single math/computer science degree that consisted of 5 math classes beyond multivariable calculus and a few relatively basic computer science classes (algorithm analysis, SQL database design, etc.). My only research experience is in economics. Now, I work at a research institution in economics where I primarily write Stata/MATLAB code. Question I'd like to get more mathematics under my belt over the next few years in order to either enroll in a PhD program in economics/finance or a M.S. program in finance. What are my options for getting more math experience that I can use in graduate school admissions? Options These are the options I thought of so far, but I would like to know more if possible.  Study enough courses through a system like Open CourseWare to gain enough experience to enroll in more advanced undergraduate classes part time, which my employer might pay for, and then ideally move into an M.S. program in applied math.  Return to my alma mater for a M.S. degree in math that would at least give me a basis to either move into another math graduate program with higher rankings or a lower-ranked graduate program in the fields of my choice.  Join the Air Force and hopefully take advantage of the GI bill to take more courses somewhere and gain entrance into an M.S. program in applied math.  (Sadly) Forgo advanced mathematics and find a consulting job, which although unpleasant in the field of economics (in my opinion), wouldn't be difficult to obtain given my research background in the field.   Do I have any other options? I also plan to take the GRE subject test in mathematics to prove that I have at least minimal knowledge, regardless of what course I pursue (since many graduate programs will require it).


What’s the difference in single thread performance between Intel(R) Xenon(R) CPU E5-2697 v2 @ 2.70GHz 2.69 GHz & Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz?

I want to compare (not precisely, no accurate benchmarking, just the big picture) two CPUs, the one of my main gaming PC (built in Feb 2011) and the one of my newest PC (built last week).  One has an Intel Core i7 870 and the other has an Intel Core i7 3630QM.  One would think that the new one would destroy the other or at least show a noticable difference, and I am only taking about their specifications, not even in practice! and it is not that obvious...  I mean when looking at the specs, the frequencies look close, the number of cores is the same, I mean what in the specs make one of those CPUs better that the other...  Comparing CPUs used to be way easier back in my days ;)


==> Until more recently, Product XYZ had not been ready but Provider XYZ has made changes to the product a while ago that address the issue and   markets are now embracing the product.   Is this sentence grammatically correct? My thinking was:    1) Had not been / past perfect --> It is ready ever since Provider XYZ has released the product but since that was a while ago its a condition that changed in the past before the present.   2) Has been /present perfect --> Provider XYZ released a product but this release is affecting the present and future and I want to underline that by using present perfect. I also don't know the exact moment when they released it.    Thank you for your help, much appreciated. Just wanted to make sure I am using past perfect correctly. At what point would you use "past tense" in a sentence like this? E.g. if you know exactly when the product was released.

I came across something really strange today in class. Because it was an anecdote, the story changed from past to present. Then, in the same sentence, the writer used the past perfect tense with the present tense.     "I go into the room, and see the guy take my bag that I had left there."   Can this possibly be correct?


I have inherited the computer of a former employee. My office is on a small network. I log onto the domain with his old credentials. I have tried changing it in Control Panel under user account settings but it does not give me that option. Maybe because it is the admin account? I've been using it for a while as is, but would prefer to see my name instead of old employees, but I would also like to keep all my account settings, files, docs, etc. I've also just upgraded to Windows 8. Thanks in advance for the input.  My user account properties:    Old user account properties, note, there is only one tab:    Computer name:

When I log in on a Windows 8 machine for the first time with my Microsoft Account (by providing an e-mail address), a new user folder is created:  C:\Users\dzinx_000   In previous versions of Windows, I could choose the name of this folder (it was equal to my username). As I use the commandline often, it is quite annoying to me.    Can I somehow rename it to dzinx?  Does simply renaming the folder break everything?


Can you please help me with this one? I'm having a physics test and I could really use your help.  So the problem is, can the total mechanical energy of an object be less than the objects kinetic energy?

I was solving a true or false question regarding total mechanical energy and the following was the problem.     It is possible for a moving object to have negative total mechanical energy.   This is my claim.  Total mechanical energy is defined as   $$M=K+U$$  where $K=\frac{1}{2}mv^2$ and $U=mgh$.  No matter which direction the object is moving $K$ must be positive due to the $v^2$. (I am assuming that mass is also never negative.)  Potential energy is also positive because $g=9.8$ and height is a distance, which is also non-negative.  And yet, the problems says that the answer is true, as in the total mechanical energy is allowed to be negative.  What am I not seeing here ?


Is there a simple way to add symbols (circles, triangles etc) to the end of a line in QGIS?

I would like to show arrowheads in the endings of every drawn linestring.  Is it possible in QGIS?    I have been trying to use a marker line but repeats all de arroheads all over the line, it is not restricted to the ends: