I'm writing a script and currently need to automate the processes of change a line in a file from     <policy domain="path" rights="none" pattern="@*"/>   to     <policy domain="path" rights="all" pattern="@*"/>   (changing "none" to "all") while maintaining spacing. What's the easiest way of doing this from the command line without using a ton of external packages?

What's the simplest way to do a find and replace for a given input string, say abc, and replace with another string, say XYZ in file /tmp/file.txt?  I am writting an app and using IronPython to execute commands through SSH — but I don't know Unix that well and don't know what to look for.  I have heard that Bash, apart from being a command line interface, can be a very powerful scripting language. So, if this is true, I assume you can perform actions like these.  Can I do it with bash, and what's the simplest (one line) script to achieve my goal?


This specific thought experiment is for a story I'm writing. Assume a spacecraft can travel at 3/4 the speed of light. It leaves Alpha Centauri A and travels 3.6 LY. Being a non-physicist layperson I used the basic Time=Distance/Velocity. This made for an approximation of 4.7 years to travel 3.6 LY at $(3/4) c$ (please correct me if I'm wrong). However, that is not accounting for the time dilation that occurs when an object travels at near the speed of light. I know that for objects traveling at such high speeds, time will pass much slower than normal whilst the point of origin time will pass much faster. This results, I believe, in the traveling object seeming to move slowly e.g. more time passes, while the traveler will experience time more slowly e.g. less time passes. My question(s) are: for the $(3/4) c$ traveler, how long would it appear to take to reach 3.6 LY from their point of origin? For the observer (Alpha Centauri), how much time would pass for them before the traveler reached their destination?

Suppose I wanted to travel to one of the recently discovered potentially Earth-like planets such as Kepler 186f that is 490 light years away. Assuming I had a powerful rocket and enough fuel, how long would it take me?


I am trying to run a service on port 61009 on localhost on centos8, but getting connection refused. I tried opening the port using firewall-cmd command. The output of the firewall-cmd --list-all looks like the following. public (active)   target: default   icmp-block-inversion: no   interfaces: eth0   sources:    services: cockpit dhcpv6-client ssh   ports: 61008-61010/tcp 61022-61024/tcp 61009/tcp   protocols:    masquerade: yes   forward-ports:    source-ports:    icmp-blocks:    rich rules:        My OS details are as follows. NAME=“CentOS Linux” VERSION=“8 (Core)” ID=“centos” ID_LIKE=“rhel fedora” VERSION_ID=“8” PLATFORM_ID=“platform:el8” PRETTY_NAME=“CentOS Linux 8 (Core)” ANSI_COLOR=“0;31” CPE_NAME=“cpe:/o:centos:centos:8” HOME_URL=“https://www.centos.org/” BUG_REPORT_URL=“https://bugs.centos.org/” CENTOS_MANTISBT_PROJECT=“CentOS-8” CENTOS_MANTISBT_PROJECT_VERSION=“8”  telnet localhost 61009 telnet: connect to address ::1: Connection refused Trying 127.0.0.1... telnet: connect to address 127.0.0.1: Connection refused How can i open ports on centos8?

This is a  about Connection Refused    We see a lot of questions to the effect      When I try to connect to a system I get a message      Connection refused      Why is this ?


Ok so here is the question. I am trying to insert a variable into my query that is pre-defined. However it is not working. The query works if I just give it a value, but when I insert a variable into it, it fails. help?  $connection = new mysqli('localhost', 'user', 'pass', 'db');   $username = "test";  if (mysqli_connect_errno()) {     printf("Connect failed: %s\n", mysqli_connect_error());     exit(); }  if ($result = $connection->query("INSERT INTO users (username, password, email, firstName, lastName, createDate) VALUES ('".$username."', 'test', 'test', 'test', 'test', 'test')")){    echo "success";   $result->close();  } else {   echo "error"; }  $connection->close(); ?>   If I replace $username with any value, it works.. Am I missing something here?

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?


I have a CentOS server running Exim, with a standard LAMP stack installed.  The problem is that there is a process that is sending out unsolicited emails, AND I do not know how to locate the process.  Here is what I have done:   I have done a tail /var/log/exim_mainlog to see what is going on.  This is some of the output:  2016-02-14 01:42:00 SMTP connection from (jabosupply.dcr103.com) [255.255.255.255]:33165 closed by QUIT 2016-02-14 01:42:00 1aUlhH-0006fx-UO => cpm147 <lstockings@site1.com> R=localuser T=local_delivery 2016-02-14 01:42:00 1aUlhH-0006fx-UO Completed 2016-02-14 01:42:03 1aUlhL-0006gS-RD <= AmeliaCruz@site2.com H=(site2.com) [255.255.255.255]:54467 P=esmtp S=25154 id=456dfg4.G880UOMSX255.255.255.255@lisalou.vegan$ 2016-02-14 01:42:04 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1aUlhL-0006gS-RD 2016-02-14 01:42:04 1aUlhL-0006gS-RD => cpm147 <duke@site1.com> R=localuser T=local_delivery 2016-02-14 01:42:04 1aUlhL-0006gS-RD Completed 2016-02-14 01:42:04 SMTP connection from (site2.com) [255.255.255.255]:54467 closed by QUIT 2016-02-14 01:42:05 SMTP connection from [255.255.255.255]:40445 (TCP/IP connection count = 5) 2016-02-14 01:42:05 no host name found for IP address 255.255.255.255 2016-02-14 01:42:11 SMTP connection from [255.255.255.255]:58622 (TCP/IP connection count = 6) 2016-02-14 01:42:12 1aUlhU-0006hP-C9 <= GregoryLittle@site3.com H=(site3.com) [255.255.255.255]:48668 P=esmtp S=37419 id=DV59FTL1CMF.gfjh3ufdg45q1111.6603.WE@chimail1.m$ 2016-02-14 01:42:12 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1aUlhU-0006hP-C9 2016-02-14 01:42:12 SMTP connection from (site3.com) [255.255.255.255]:48668 closed by QUIT 2016-02-14 01:42:12 1aUlhU-0006hP-C9 => cpm147 <duke@site1.com> R=localuser T=local_delivery 2016-02-14 01:42:12 1aUlhU-0006hP-C9 Completed 2016-02-14 01:42:17 SMTP connection from [255.255.255.255]:40445 lost 2016-02-14 01:42:17 1aUSE4-0000ZZ-Tp == erika.guerra@fresno.heald.edu R=dkim_lookuphost defer (-1): host lookup did not complete 2016-02-14 01:42:17 1aUj64-0004bS-6P Message is frozen 2016-02-14 01:42:17 1aULQ4-0002bv-Bs Unfrozen by errmsg timer 2016-02-14 01:42:18 1aULQ4-0002bv-Bs ** alisa_mckinney@site4 R=dkim_lookuphost T=dkim_remote_smtp H=smtp.secureserver.net [255.255.255.255]: SMTP error from remote mail server $ 2016-02-14 01:42:18 1aULQ4-0002bv-Bs alisa_mckinney@site4: error ignored 2016-02-14 01:42:18 1aULQ4-0002bv-Bs Completed  Tried turning off mail for the server via WHM - this is successful, but not a permanent solution! Done a top to see the exim processes.  There are anywhere from 0 to 1 to about 7 of them, with user of either root or mailnull.  So the hosted user account is not identified.   I am thinking there must be a PERL script or PHP script somewhere that is running this.  I need to identify it.  Can anyone help me locate the physical source of the script that is running.  P.S. My server is not high-use and none of the websites have mailing scripts.  I'm thinking this must have been injected so I am also changing passwords.  But my priority is to locate this.

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


I own a pair of usb powered speakers, and I am having trouble finding how to set the usb speakers as the default output. I found the setting where you can switch the outputs but no where to asssign a default. I took screenshot here:

Ubuntu's desktop gui is great for changing audio settings (System->Preferences->Sound), like the default input/output device and setting the volume.  However, I would like to be able to do these things from the command-line. What tool is the gui using behind the scenes?


int[] testArray = new int[200000000];  Stopwatch st2 = new Stopwatch(); st2.Start();  for (var j = 0; j < testArray.Length; j++) {  }  st2.Stop();  Console.WriteLine("Total milliseconds - FOR LOOP: {0}", st2.Elapsed.TotalSeconds);    Stopwatch st = new Stopwatch(); st.Start();  foreach (var arr in testArray) {  }  st.Stop();  Console.WriteLine("Total milliseconds - FOREACH LOOP: {0}", st.Elapsed.TotalSeconds);   Results:     for: 0,7046522 seconds   foreach: 0,05508682 seconds   Why is my foreach faster? I thought that my for loop would be faster than the foreach

In C#/VB.NET/.NET, which loop runs faster, for or foreach?  Ever since I read that a for loop works faster than a foreach loop a  I assumed it stood true for all collections, generic collections, all arrays, etc.  I scoured Google and found a few articles, but most of them are inconclusive (read comments on the articles) and open ended.  What would be ideal is to have each scenario listed and the best solution for the same.  For example (just an example of how it should be):   for iterating an array of 1000+ strings - for is better than foreach for iterating over IList (non generic) strings - foreach is better than for   A few references found on the web for the same:               [Edit]  Apart from the readability aspect of it, I am really interested in facts and figures. There are applications where the last mile of performance optimization squeezed do matter.


Today when I'm taking a look at my terminal, I realized that there is a weird string in my shell prompt.  It seems that I've never seen this weird string before.  What is that for?

My computer name in System Preferences > Sharing is set to "archos", but is showing as "iphone" on Terminal. It just started doing this after I loaded Xcode for doing iPhone development: Last login: Mon Nov  7 14:46:55 on ttys001 iphone:~ travis$   Any ideas what could be causing this?


From :    How does the system extrapolate from the existing userbase how many users there are likely to be with at least a certain rep score in forty days' time? I can think of a few possible algorithms none of which make much sense. Has the algorithm used ever been made public?  (I've seen  from 2012, but I don't think this is a duplicate. The old meta post has a lot of guesses at possible algorithms, but nothing is confirmed.)

Taking Biology as an example, :     Every site needs a solid group of core users to assist in moderating   the site. We recommend:         150 users with 200+ rep (on pace for 83 users  at 90 days)   10 users with 2,000+ rep (on pace for 2 users at 90 days)   5 users with 3,000+ rep (on pace for 0 users at 90 days)      At the current time, there are   70 users with 200 rep or more 2 users with 2000 rep or more   See  (36 per page)  So assuming that the projected extra thirteen 200 rep users are the next thirteen closest, the Area 51 projections say that the thirteenth user is expected get 44 reputation points, that is, 22% more than they have currently in the next 17 days.  Yet this doesn't seem to be the same logic as applied to the next category. Four users are within 170 reputation points (8.5% more) and some are only 22 reputation points (1.1%) away from crossing the threshold. Surely they are more likely to do this in the next seventeen days than the 200 reputation points users (I am sure their reputation per day is higher too) so why don't these users show up in the on pace stats?  Could the projections be broken for the middle category?  Similarly for the third category, a user is 66 reputation points (2.2%) away from the 3000 mark yet doesn't show up in that bracket. Surely they should be doing at this point?  I also think it's unlikely to be a caching problem as some of the 2k users haven't gained reputation points over the last couple of days but are still within striking distance.


In Season 5 of Stargate: SG-1, team member Daniel Jackson was briefly replaced by Jonas Quinn, a human from Langara. In addition to an optimistic, almost child-like curiosity about everything, Quinn shows numerous intellectual abilities above and beyond the average human. He can read quickly, remembers everything he reads or watches on TV (photographic memory?), and is even able to learn new languages abnormally fast. He often shrugs off his abilities, simply calling himself "a quick study".  Unfortunately, we never see much of Quinn's planet or nation, with other Langarans only appearing in a couple of episodes. Quinn eventually leaves SG-1 to return there, joining the new ruling council on his planet and hoping to unite his people. However, we never really hear any more about Quinn or the Langaran people after that.  Is Jonas Quinn typical of humans on Langara, or is he unique even there?

Did Stargate SG-1 ever explain why the Kelownans like Jonas were able to learn so fast?  Did it have something to do with the experiments that were conducted by the Goa'uld?


Question: $$\lim\limits_{x\to\infty}\frac{1}{x}\int_0^x\frac{dt}{2+\cos(t)}$$  My approach:  $f(x)=\dfrac{1}{2+\cos(t)}$  is continuous on $\mathbb{R}$  $\implies$ $\int_0^x f(t)\,dt$  is a antiderivative of $f$ $\iff$ $\iff$  $(\int_0^x f(t)\,dt)'=f(x)$  $$\lim\limits_{x\to\infty}\frac{\int_0^x\frac{dt}{2+\cos(t)}}{x}\stackrel{L'H}{=}\lim\limits_{x\to\infty}\frac{\left(\int_0^x\frac{dt}{2+\cos (t)}\right)'}{x'}=\lim\limits_{x\to\infty}\frac{1}{2+\cos(x)}$$ which does not exist  Note: In order to use L'Hospital rule it is only necessary that $\lim\limits_{x\to\infty}g(x) = \pm\infty$ , $g$ being the function in the denominator.   The book from which I took this problem says the answer is $\frac{1}{\sqrt 3}$. How do I get to that result, is my approach correct?

$$\lim _{x\to \infty }\frac{1}{x}\int _0^x\:\frac{dt}{2+\cos t}$$  Can someone explain to me if it is a limit of type $\frac{\infty}{\infty}$ or not and why ? I considered it to be one, applied L'Hospital and got $\cos\infty$, which would mean that the limit does not exist, but the answer is $\frac{1}{\sqrt{3}}$


Is it ok If we enter the country together however the adult leaves them in the state to go travel?

My daughter who is just under 18 has a child accompanied visa to the UK. I am traveling with her to the UK for a few days. We return from UK on the same day except that she returns to India and I am heading to San Francisco an hour later on the same day.   Is that okay or will we have an issue at immigration into the United Kingdom?


I know that atmospheric lensing is what causes the moon to look bigger on the horizon, but I assume this effect is still taking place when the moon is overhead too, albeit to a smaller effect. However, would the moon appear to change in size if you looked from an earth with no atmosphere?

Possible Duplicate:          I made a little research about this and found this article  that states the explanation of the moon being bigger at the horizon  is still debated.   I found this which looks pretty 'big'  but however this kind of repetitive shots  show no decrease in the aparent moon radius.  What I am trying to understand is if it is a real illusion, if the atmosphere makes the image bigger or what other explanation could be possible and of course plausible.


I have seen this question asked before, but never has it gotten a real answer. With the popularity of this plug I find it hard to believe it does not have a standard name or IEC name.  Does anyone know the real name of this or is it truly just an oddball DC Barrel-jack connector that HP and Dell love to use?   Here is a related question with no good answer:  And another here:  Just to clarify I really care about the female jack, not the plug.

So I'm wondering if anyone has any information about the Dell power supplies which have 3 contacts on the barrel.    I know the 3 are power, ground, and some sort of communication link. Does anyone know what the communication line is for and/or what kind of protocol it uses?  Thanks  EDIT The reason I ask is I'm considering trying to build my own semi-advanced charger (not for a laptop but something else... it's a long story) and while I'm sure I could figure out a charging circuit given the internet as a resource, I was wondering what they use the communication line for and if it's necessary for my purposes. It seems the answer is no since I will be the only one using my device and thus don't need to worry about people plugging in not kosher chargers...


I'm looking for a word, term, or phrase that refers to a type of behaviour; somewhat similar to what's commonly known as "Malicious Compliance"; but without the necessary implication of malice aforethought.  That is to say; the behaviour in question is characterised by a strict, blind adherence to the rules. Regardless of (or ignorant to) the potentially negative impact it may have or the damage it could cause without considering any unique, individual, or extenuating circumstances. Possibly even to the detriment of the system that the rules are intended to protect.

I'm looking for a single word noun that would perfectly summarize the stereotypical nerdy uptight virgin student council president.   Basically, a more proper version of the slang word "square": a person who always does what they're supposed to even if it means sacrificing things like fun and happiness and who casts a judgemental gaze on anyone who does otherwise.   I'm trying to describe a certain person, and so far I've got "an OCD, judgemental, paranoid, uptight", but I need a noun to finish it off.


I have a Canon 60D (crop factor 1.6x) and an 85mm f1.8 prime lens. Now I want to add a 2x teleconverter and attach the 85mm lens to it.   My question is: What will the effective aperture be?

I just bought a Canon 2X extender and I always believed that it would only result in 2 stops' loss of light and not change the aperture.    However, when I tested this extender on a Canon 135mm f/2 lens, the maximum aperture I could set went down to F/4.  So it kind of confused me, because if I step down the aperture to f/5.6, is it actually setting the aperture to f/5.6 or f/2.8 (i.e., 1 stop below f/2)?


I am planning to take a 1 week trip outside the US in April 2018. My H1B visa expires first week of September 2018. I just want to know if there will be any issue at port of entry in the US with 4 months left on my H1B visa. Thanks.

I'm a bit surprised from my US Visa. I plan to go to a conference on 3rd of April. Amazingly though, the visa expiration date is written as April 3rd.  So what does that mean. Can I enter the US on April 3rd? or should I enter one day earlier?


I am writing a program that will take a disk file with an array of strings with a max size of 100 and do a few things to them. However, I am getting a console error due to my bubblesort method searching for and trying to sort 100 (the length of the array) items while the disk file may have, lets say, 15 items. The bubblesort method is returning a console error due to it searching for the remaining 85 items and trying to sort 85 blank items. I am totally lost on how to fix this problem. Is it possible to get the items in the disk file, pass them onto another array and then bubblesort that one so the 85 blank spots are eliminated? Or is adding a counter an option that will solve my problem? I am fairly new at java coding so any help would be greatly appreciated.  Here is the error i am getting:   Exception in thread "main" java.lang.NullPointerException at java.lang.String.compareTo(Unknown Source)     at Assignment7.bubbleSort(Assignment7.java:52)     at Assignment7.main(Assignment7.java:12)  here is my code:   import java.io.*;  import java.util.*;  public class Code3 {  public static void main(String[] args) throws IOException {       String[] list2, targets, list1;     list1 = getInput("C:\\Users\\Steave\\Desktop\\file14.txt");     list2 = bubbleSort(list1);                                                 targets = getInput("C:\\Users\\Steave\\Desktop\\upload6.txt");      double seqAvg = seqSearch(list1, targets);     double binAvg = binSearch(list2, targets);     System.out.println("Average number of searches for the seqeuntial search is " + seqAvg);     System.out.println("Average number of searches for the binary search is " + binAvg);  }//end of main method  public static String[] getInput(String filename) throws IOException {     String[] inputArr = new String[100];      Scanner in = new Scanner(new File(filename));     int count = 0;     while(in.hasNext()) {           if (count < 100){             inputArr[count++] = in.next();         } else {             break;         }          }            in.close();     return inputArr;  }// end getInput method     //This method will sort the array and pass it onto a list. public static String[]bubbleSort(String[] inputArr) {      String[] Array2 = inputArr.clone();      for (int i = 0; i<Array2.length; i++)     {       for (int j = 0; j<Array2.length-1; j++)       {           if (Array2[j].compareTo(Array2[j+1]) > 0)         //CONSOLE ERROR HERE           {             String temp = Array2[j];             Array2[j] = Array2[j+1];             Array2[j+1] = temp;           }        }     }       return Array2;  }// End of sort method.  //This method will do a sequential search on the list1 public static double seqSearch(String[] list1, String[] targets){       {           for (int j = 0; j < list1.length; j++)           {               for(String str:targets){               if(list1[j].equalsIgnoreCase(str)){                   return j;               }           }              {                 return j;              }          }          return -1;        }  }//end of sequentialSearch method       //This method will do a binary search on the list      public static int binSearch(String[] list1, String[] targets) {        int lo = 0;         int hi = list1.length - 1;         int mid = -1;          while( lo <= hi ) {           mid = (lo+hi)/2;            for(String str:targets){           if(list1[mid].equalsIgnoreCase(str)){               return mid;           }            hi = mid-1;             } for(String str:targets){           if(list1[mid].equalsIgnoreCase(str)){               return mid;           }       }              lo = mid+1;            {             return mid;           }         }         return mid;       }    }

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?


Is there a simple way of getting a list of figure filenames from a tex file? for example if I have included 10 png, 5 pdf and 3 eps files, is there a script that can output the filenames to a list so I can make sure they all get kept/moved to a different directory together? I've looked at the extract package, but that produces a tex file with the figure code extracted. I guess I can use 'grep', such as cat my.tex | grep eps, but just checking there isn't a standard tex command to do this.

I have a TeX document that is embedding a huge amount of figures from a fig folder that is full of another humongous amount of other figures.  I would like to move the document along with its figures, but I don't want to take the whole fig folder, just the figures in there that are embedded by the document.  Is there a package (or any other way) that allows me to, for example, print out the filenames of all the figures embedded by the document? Something like:  fig/figurename1.eps fig/figurename2.eps ... etc   I could then just copy-paste that list and add some cp's in a plain text file and automate the copy of those files to my desired location by running the file in my shell:  $ cp fig/figurename1.eps wherever/fig/ $ cp fig/figurename2.eps wherever/fig/ ... etc   Of course this is just an idea, if somebody has an alternative to the "file listing and copy-pasting in a shell file" I would be happy to listen =)


For Drupal 7, I found   What is the equivalent code for Drupal 8?  UPD: here  I found the case when you can use the code during deployments, specially when your module has updates in own dependencies.

In Drupal 7, if we wanted to push code to our environments enabling modules, we would call  in hook_update_N(). We no longer have that in Drupal 8, so how do we programmatically enable modules? Do we use Drupal 8's Configuration Manager or hook_update_N()?  A diff on the exported configuration yields this:  +++ b/cim/sync/core.extension.yml @@ -10,6 +10,9 @@ module:    config: 0    contact: 0    contextual: 0 +  ctools: 0   So it seems the module is enabled via code using Configuration Manager. We're also working with the idea of this:  function mymodule_update_8003() {   $modules = array(     'ctools',   );   \Drupal::service('module_installer')->install($modules); }   What is the correct method?


Let's say my grav cannons (D3 damage) shoot at some crisis suits (3 wounds each) and the suits fail 3 saves. I roll damage and get a one, a two and a three. Should I have rolled the dice in order? Or can I roll them together and allocate? Or do I roll them together and the other player allocates?  To see how different this could be:   If I allocate, I'll apply the three first, then the one and the two, killing two models If the target player allocates, he'll apply the two, then the three, killing one model. The one then gets applied to a fresh model, leaving it with two wounds. Or, if applied in order, I might have rolled the one first, then the three, then the two. That would kill one model and leave another with one wound remaining.

I have read the freely available , which explains the core rules. However, I am still a bit confused regarding how exactly to resolve damage.   Imagine a unit of Space Marines gets 10 shots at a unit of Orks. The weapons of the Space Marines have an Armour Penetration value of -2, and a Damage Value of 2 as well. Out of those ten shots, six shots hit. Of those six hits, four of them wound.  The next step would require me to allocate "Wounds". How many Wounds did I generate? Is it 4, because 4 shots hit and passed the Wound roll? Or is it 8, because each shot would deal 2 damage? The Ork player would then have to allocate the wounds and roll Saving Throws. Let's assume his Orks have a saving throw of 4+. Does this mean he has to roll 4 individual Saving Throws (one per shot) or 8 individual Saving Throws (one per damage). Imagine one Ork had the ability to roll Invulnerability Saves. Are those Save rolls per-shot, or per-damage?


What stops the energy produced at the hilt of the Lightsabers from extending ridiculously far?   The Lightsabers are generally sword length (or spear length for Darth Maul), so what keeps them that way?

I always see blades of lightsabers have more or less the same length (dual blades are double). Why is that?  Can't a longer or shorter length be advantage in some case?    I am NOT expecting infinite length lightsabers (due to energy issues), but have we seen adjustable length blades in the Canon?


I am trying to get a list of folders from the root directory in my JSP project and then display them to the user in a table, with links to child folders and the size of the folder. The code below is to get a list of directories inside the WebContent folder.  String absolutePath = this.getServletContext().getRealPath("/") + relativePath; String fileList = "
File Name	Size [B]	Last Updated
";  File folder = new File(absolutePath); File[] listOfFiles = folder.listFiles();  for (int i = 0; i < listOfFiles.length; i++) {     if (listOfFiles[i].isDirectory()) {         Path file = listOfFiles[i].toPath();         BasicFileAttributes attr = Files.readAttributes(file, BasicFileAttributes.class);          String time = attr.lastAccessTime().toString();          fileList += "
&nbsp;"             + "<button onclick='navigate(this);'>" + listOfFiles[i].getName() + "</button>	" + attr.size() + "	"              + time.replace("T", " ").substring(0, time.indexOf("."))              + "
";     } }   When I run the project locally, there is no problem. But after deploying my .war file on a server, when running I get a 500 error (null pointer exception) at line:  for (int i = 0; i < listOfFiles.length; i++)   Which tells me that the Folder array has not been initialized with the child folders.   I am assuming that I don't have the same access to these folders on the server as I do when I am running locally.  Any ideas how to access these folders?  P.S. The server is running on Unix.


I just realized I can't unrar .rar files on my Ubuntu machine!  What's the easiest way to accomplish this fundamental task? If possible I'd love something like 7Zip that I can just right Click, and extract and have the program worry about how to do it regardless if it's a .zip, a .rar or a .foo compressed file.


So I have a US itunes account and a German one, because the US gets stuff earlier. The German one is my main account and I use that for the mac app store and for the apps on iTunes but I mainly use the US one for movies and TV shows.  I recently bought a movie from the German account, and when I tried to stream it on the mac, it told me that this computer is already associated with an Apple ID and after switching I have to wait 90 days.   So if my understanding is correct, if I opt to use my German account to download or stream the movie I just bought, I cannot access my stuff on the US account for the next 90 days, atleast not on this particular mac?   Was this always like that? I remember being able to switch back and fourth without a problem.

On my old laptop, I used a shared Apple ID to purchase music on iTunes. It was a little tedious because it was connected to my sister's bank account, so I had to send her money before each purchase I made, so that her account wouldn't overdraw.  That laptop died, and now I have a new one with a new Apple ID connected to my own bank account. However, some of my purchased songs were lost, so I temporarily logged into iTunes with my old Apple ID to re-download them. Right when I was about to download, iTunes warned me that I would need to associate my new laptop with the Apple ID, and that after you associate a device with your Apple ID, you can't associate that device with another Apple ID for 90 days.  I really don't want to be stuck on my old Apple ID for 90 days, is there a better way to do this?


There have been  asked about the specifics of mounted combat, especially as a paladin.  and are mostly based on the rules we have in PHB p198 and on Jeremy Crawford's tweets:        The mount summoned by the find steed spell serves the summoner. It isn't an independent creature.       While ridden, the steed follows the normal mounted combat rules (PH, 198). Unridden, it has normal action options.    From what I gather from this, a mount summoned from the '' spell is intelligent and loyal enough to obey your orders without question while you are mounted on it, but is not considered an 'Intelligent creature', which could use any type of action while you are mounted, but may go against your orders. This is called an 'independent creature' in the PHB. While mounted, the non-independent creature has only the Dash, Disengage and Dodge actions, along with moving.  I have an issue with the accepted answer for this , which says the following:        The mount is "unusually intelligent": without direction it will use its movement etc. in an "unusually intelligent" way. With direction it will probably do what you telepathically say but it is an independent creature and, at the DM's behest, may do something different subject to its "unusual loyalty".   When you mount your mount you choose if you will control it or if, as it is "unusually intelligent", you will allow it to act independently as per the rules for . It all cases that I can think of, allowing it to be independent is the superior option.      To me this goes against Jeremy Crawford's tweets : the mount is not an independent creature and cannot be used as such.  Therefore, how exactly would an unmounted paladin direct, say, a summoned warhorse, during combat? Would he fully control the creature, through telepathy, allowing for attacks and trampling charges? How much does the DM has a say in whether or not the creature chooses to obey or not?

I have read so many things already that I'm more confused than before. So decided to ask this by myself.  My paladin just got his Find Steed spell, and after some tweaking and talking, he decided to get a Worg and I was okay with it. This last session was his first time using it and I have few doubts when it comes to combat.  I know that while mounted, he uses the mounts movement and actions. But what about when unmounted? What if the combat began with him walking by his mount's side?   Does the mount share his initiative? Are the actions that the mount do, part of the Paladin's actions? Or are they both separately, having his Action, Movement and Bonus Action and then the mounts Action and movement?   We've stated that it can understand him but not talk back, he just telepathically receives feelings as a feedback to his commands, knowing that the mount understood what he needed. Last session he just said things to the mount like "I tell the mount to protect the ranger and the druid" and in case they got hit, it would attack them, but it didn't really do anything at all, as I didn't know when it would act and I had too many things already to remember about the mount.


Somewhere in my document I have some equation:  \begin{equation}     \label{some_equation}     ... \end{equation}   I would like to repeat this equation later (so that the reader does not have to flip back and forth between sections), but would like it to appear with the same label (e.g. if it was numbered as equation (1), I would like its "clone" to also appear with the numbering (1)). Is there an easy way to do this?

Let's say I have written an equation in my paper and numbered it:  y = a + bx    (1)   Then, later in the paper, I want to remind the reader by showing the same equation with the same equation number.  Sure, I can repeat the equation, but LaTeX gives it a new equationn number:  y = a + bx     (2)   How do I force LaTeX to use the original equation numbers?


In reading through the original GCM specification (), the composition of the 128 bit Initialization Vector as a concatenation of a 96b nonce and a 32b unsigned wrapping counter seems arbitrary and forces the scrambling pattern to repeat every 232 16-byte block.  Is the algorithm expected to be secure for significantly longer stream lengths if for example the IV were a 128b nonce XORed with a 64b or 128b counter, or are there known cryptanalysis issues that begin to arise?


Is there any additional advanced search operators that would enforce the existence of [=1] in search results? Using double quote "[=1]" does not work. I couldn't find relevant info in   In particular, I'm looking to search in  where such argument can show up in the code.  This particular expression currently cannot be searched with Google nor Bing advanced search operators.

Situation: It started out as me  for the literal string C-c in  but it ended up omitting the - sign and showing results which contained the strings C/C++ and C & C++.  is an example of a post which contains that string of characters (yet fails to show up in the results).  Things I've tried:   post suggests that I can use the undocumented code: operator, but when I do that, it just wraps the whole term in double quotes like .  As @terdon in Unix & Linux chat has , using this  does yield some relevant results, but it doesn't show me  that is supposed to be there. edit: It appears that the Symbolhound query no longer returns that result.  Finally,  says that you can search for literal characters, but as you can see:    Quoted phrases are exact matches except for case-sensitivity, for example, you can search  or .  The second example (symbols) leads to 0 results.  So by now I assume that the search engine has changed (but the old documentation still lingers on this site). Is there a method for me to search for strings that include special (or is it literal?) characters?


The closest I got was umask to change the default permissions set for files/folders. However, umask doesn't seem to allow enabling the x bit for files:  The base permissions for directories are 0777 (rwxrwxrwx) and for files they are 0666 (rw-rw-rw-).   I also saw this  which makes sense, but still, umask clearly has an involvement in the issue, not just touch's code, because when I change umask, touch's results are affected).  Is there any way to create files with the execution bit set, at least for the user section (ideally -rwx-r-x-r-x = 755)

When writing answers on here, it's often necessary to create a new script and chmod +x it to make it executable. I won't go into whether this is a good thing or not, but explaining to people that they need to fire in three separate command (and teaching them to use nano!) is a bit of a waffle.  Is there anything easier?


I just downloaded the latest version of Mozilla Firefox For Developers and Thunderbird Mail, from the mozilla's official site...  Both are .tar.bz2 files, I just clicked on it, but they are not executing.  Tried a lot of the other resources, tried the methods mentioned in the best questions on askubuntu.com too, but couldn't installed it.  How can you I install them, if anyone can tell me the correct way please.  Thanks in advance.

Mozilla released the Firefox Developer Edition! How do I install it on Ubuntu?  Source:


I'm reading an article about Direct Linear Transformation which processes data using SVD, and the data set is standardized so that it has zero mean and unit standard deviation (n.b., some people call this transformation 'normalized').  In that article, it is said that for numerical reasons, the data set has to be normalized to make sure the DLT algorithm stable.   I wonder what are those numerical reasons? Does it mean if I have 2 data sets of the same objects, if no standardization is done, the DLT algorithm will give out 2 numerically different results?  UPDATE  In computer vision,  (DLT for short) is a method of homography estimation, it solves the overdetermined linear system via SVD $$Ah=b$$to find a solution $h$ under constraint $\|h\|=1$. Actually it finds the least square solution which minimize $\|Ah - b\|$.  I understand the basic idea of this algorithm, but it is recommended to standardize the data set before applying DLT on it, and  is a intro about how to do the standardization. It is lectured that data standardization is important to DLT, without standardization the results from DLT are not stable, and the reason is that DLT is quite dependent on the coordinates of the points in the data set.  I wonder why? Just because DLT involves solving the linear system using SVD and $A$ might be singular?

In what circumstances would you want to, or not want to scale or standardize a variable prior to model fitting?  And what are the advantages / disadvantages of scaling a variable?


I'm not sure anyone will know the answer to this question, unless you are responsible for writing the Jave API, but when the Java API says "equals", does it always mean that a.equals(b) evaluates to true, or sometime does it mean a == b is true? I have recently extended a class and wondered if I needed to override a method depending on where or not it used == or .equals. Specifically, I extended  and was curious about the .isEqualTo(Object other) method. I checked the source () and found that this method uses .equals for comparison. I'm curious if I can be confident that when I read things like      "Creates a new BooleanExpression that holds true if this ObjectExpression is equal to a constant value."   that the method is not using the == operator. Although, as I think of it, the API can't possibly mean .equals either, since (for example)  String constant = "constant"; ObjectExpress<String> stringExpression = new MyStringExpression("constant");  constant.equals(stringExpression)   will always evaluates to false. So maybe my question should be "when the API says 'equals', does it always refer to the most reasonable way to apply .equal or sometime does it refer to the analogous way to apply ==?"    EDIT  I think based on the answers I should clarify: this is not a question about the difference between == and .equal. It is about to which the Java API is referring when it uses the English word "equals".

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Use Schröder-Bernstein Theorem to show construct a bijection between $(0,1)$ and $(0,1]$  Let $f : (0,1) \rightarrow (0,1] $ be defined as $x \mapsto x$  and $g : (0,1] \to (0,1)$ be defined as $x \mapsto \frac{x}{2}$  The theorem states if we have two injective functions $f,g$ between sets then there exists a bijective function $h$ between them.  Define   $A^*  \subset (0,1)$ to be $\{x \in (0,1) : x = \frac{p}{q} \,\&\, p = 1 \, \& \, q = 2^k, 1 \le k \} $ and   $ A'  \subset (0,1) $ to be equal to $(0,1) \backslash A^*$  and  $B^*  \subset (0,1]$ to be $\{x \in (0,1] : x = \frac{p}{q} \,\&\,  p = 1 \, \& \, q = 2^j, 0 \le j \}$  $ B'  \subset (0,1] $ to be equal to  $(0,1] \backslash B^*$   Define $h : A \to B $ to be defined by $ h(x) \displaystyle \Bigg \{ \begin{array} x f(x) = x \,\, \text{if} \, x \in A' \\ g^{-1}(x) = 2x \, \text{if} \, x \in A^*\end{array}  \\  $  So $A^* \cup A' = (0,1) \,\&\, B' \cup B^* = (0,1] \,\&\, A' \cap A^* = \emptyset \,\&\, B' \cap B^* = \emptyset $  and  $A^* \mapsto B^* \, \& \, A' \mapsto B'$

How to define a bijection between $(0,1)$ and $(0,1]$?   Or any other open and closed intervals?   If the intervals are both open like $(-1,2)\text{ and }(-5,4)$ I do a cheap trick (don't know if that's how you're supposed to do it): I make a function $f : (-1, 2)\rightarrow (-5, 4)$ of the form $f(x)=mx+b$ by \begin{align*} -5 = f(-1) &= m(-1)+b \\ 4 = f(2) &= m(2) + b \end{align*} Solving for $m$ and $b$ I find $m=3\text{ and }b=-2$ so then $f(x)=3x-2.$  Then I show that $f$ is a bijection by showing that it is injective and surjective.


I'm actually not sure if it was a book series, but there was a question to identify this story several months ago that linked to a website that explained the history and events that took place in this universe.  The setting was in the future in our solar system. There was a plague on Earth, "The Black Plague" I believe, that was killing plants on farms, and  it found it's way into orbital farms. There was an event where contact with either Venus or Mercury was lost and the machines on the planet took over. They started shooting at whatever ship came close, then started sending machines out into the solar system to assimilate other machinery.  I also remember a section describing artificial intelligences that are god-like. One in particular, named Gaia I believe, saved the solar system from the machines and plague. There were multiple tiers of existence, or something, with combinations of biological and artificial entities.  I remember a section describing how people who were living around Jupiter didn't really care about what was happening to the inner planets, but the machines that were attacking eventually reached them and it was bad.

There is a site with lots of stories all set in a future with super powerful AIs regarded as Gods, the most powerful being matrioshka brains. They have a specific terminology but I can't remember their names. Earth has been converted into a similiar godlike computer called "Gaia" and has expelled all humans creating a dystopian exodus across the solar system. And something about rogue Von Neumann machines causing a huge crisis dubbed the "technopocalypse".


We have in our LAN a nginx server configured in https.  In front, we have Haproxy with SSL and we need to establish a connection SSL from backend to nginx server. Is it possible to do this?  Client -> Haproxy:SSL -> SSL:Nginx  backend pkiservices     mode http     option httplog     option forwardfor     server pki pkiservices.example.com:443   With this configuration, Nginx return an erreur 400 (The plain HTTP request was sent to https port).  Thanks in advance

I would like terminate SSL at HAProxy, do some manipulation on the header, rewrite URL and re-encrypt traffic and send to backend servers as SSL?  I can't seem to find a way to do this. I can get regular SSL termination done, and send plain HTTP requests to backend. But I need to send SSL to backend.   I would like to have the following features:   Extract x-forwarded-for headers, to get the real client IP behind proxy. Implement session stickiness using cookie.  Do some URL rewriting.  Send SSL traffic to backend using cookie based session stickieness.    Unless I terminate SSL at haproxy end, I cannot get URL rewriting done.   Any help from the good people here would be highly appreciated.


After safely remove or eject it, i want to remount it without unplug it, and re-plug it again .. so Any suggestion pls?  PS  after using eject all usb memories are out of fdisk command scope i don't think it is that easy   `       Device Boot      Start         End      Blocks   Id  System /dev/sda1       109473792  1953525167   922025688   83  Linux /dev/sda3         2050048    99706297    48828125   83  Linux /dev/sda4        99708926   109471743     4881409    5  Extended Partition 4 does not start on physical sector boundary. /dev/sda5        99708928   109471743     4881408   82  Linux swap / Solaris  Partition table entries are not in disk order`   None of them is the usb memory

When I right-click the desktop icon for my USB drive or SD card I have the choice to "Eject" or "Safely Remove Drive":    In the Tree side pane in Nautilus, I can either "Unmount" or "Eject":    The Places side pane in Nautilus has some kind of eject icon:    What do all of these do?  Specifics I've been wondering about include:   What happens when a drive has multiple partitions mounted? Under what conditions is a prompt to empty the trash displayed? Do any of these result in a state in which the drive cannot be mounted again without first being physically reconnected?


I have a series of eps images that I would like to display in a sequence of slides in a Beamer presentation. The result would be like a stop motion animation effect. The images are titled image1.eps to image50.eps. I can obviously do this with a sequence of 50 identical slides, differing only in the index on the image file, but I wanted to see if it's possible to automate the process somehow.

I am currently working on a conference presentation and I am using the very nice tikz and pgfplotspackages in combination with beamer.  To stress out some content in my figures, I use beamer's overlay system.  When I use some small tikzpictures everything is integrated inside the document using some \input commands. However, for large pgfplots figures (you see me coming), I have quite long compilation times.  My current solution is to precompile my big pictures separately using multiple tikzpictures and to call some \includegraphics with overlay options.  Beamer code  \documentclass{beamer} \begin{document} \begin{frame} \includegraphics<1>[page=1]{image} \includegraphics<2>[page=2]{image} \includegraphics<3->[page=3]{image} \end{frame} \end{document}   where image is built using   \documentclass[tikz]{standalone} \begin{document} \begin{tikzpicture}     \begin{axis}[]     % Plot to be displayed on overlay 1         \addplot[domain=0:1,samples=100]{x};      \end{axis} \end{tikzpicture} \begin{tikzpicture}     \begin{axis}[]         % Plots to be displayed on overlay 2         \addplot[domain=0:1,samples=100]{x};          \addplot[domain=0:1,samples=100]{x^2};      \end{axis} \end{tikzpicture} % And so on \end{document}   I know there are some externalization ways to do this, but I was wondering what the opinion of the community was on this matter.  Sorry in advance, if this is a double.  EDIT related to standalone beamer option   Using standalone with the beamer option seems to produce an nteresting result (thanks samcarter). However, the output has the size of a beamer frame, instead of fitting the pgfplots axis. See the MWE below.  \documentclass[beamer]{standalone} \usepackage{pgfplots} \begin{document} \begin{standaloneframe} \begin{tikzpicture} \begin{axis}[] \only<1>{\addplot[domain=0:1, samples=100]{x};} \addplot[domain=0:1, samples=100]{x^2}; \addplot[domain=0:1, samples=100]{x^3}; \only<4>{\addplot[domain=0:1, samples=100]{x^4}}; \end{axis} \end{tikzpicture} \end{standaloneframe} \end{document}


There are 2 ends. Namely south end a north end. Distance between both ends are 120metres  If 2 toy cars drive from both ends at same time when will they meet. If the toy car from south to north goes in a speed of 12 metres per second and the toy car from north to south goes in a speed of 8 metres per second! I got an answer as 7.5 seconds. But I'm not sure with it. Please big help if you can solve this out.

At 10:30 am car $A$ starts from point $A$ towards point $B$ at the speed of $65$ km/hr, at the same time another car left from point $B$ towards point $A$ at the speed of $70$ km/hr, the total distance between two points is $810$ km, at what time does these two cars meet ?  This is what I have tried,     $t_1 = \frac{810}{65} \,$ km/hr $= 12.46 \, $hr    $t_2 = \frac{810}{70} \,$ km/hr $= 11.57\,$ hr     $t_1-t_2 = 0.89 \,$ hr    $t_1-t_2 = 0.89\cdot 60 = 53.4 \,$ minutes   but this couldn't be the answer because how could these two cars could meet after $53.4$ minutes ?


I am wondering why do we say "It's about time that I did something about that.", because I was expecting the present tense after "It's" and here I don't get why we say "I did".

It's time colleges helped you compare apples to apples. (The Boston Globe)  If the time is a present moment, why does the journalist use "help" in the past tense? Or is "helped" subjunctive?


I want to distribute a Python package with . Along with the package the following should be installed:   a starter script  a .desktop file to run the start script an icon for the .desktop file   I used the following setup.py file (full version is ):  from setuptools import setup  setup(   # ...   data_files=[     ('share/icons/hicolor/scalable/apps', ['data/mypackage.svg']),     ('share/applications', ['data/mypackage.desktop'])   ],   entry_points={     'console_scripts': ['startit=mypackage.cli:run']   } )   The starter skript trough entry_points works. But the data_files where put in an egg file and not in the folders specified, so they can't be accessed by the desktop shell.  To work around this, I used the following setup.cfg file:  [install] single-version-externally-managed=1 record=install.txt   This does work, but it kinda feels to me more like a workaround. Am I doing something wrong here?  What's the preferred way to handle this?

Currently I'm using the auto-tools to build/install and package a project of mine, but I would really like to move to something that feels more "pythonic".  My project consists of two scripts, one module, two glade GUI descriptions, and two .desktop files.  It's currently a pure python project, though that's likely to change soon-ish.  Looking at setuptools I can easily see how to deal with everything except the .desktop files; they have to end up in a specific directory so that Gnome can find them.  Is using distuils/setuptools a good idea to begin with?


Suppose $(X,M,\mu)$ is a measue space with $\mu(X)=1$ and $f:X\rightarrow[0,\infty)$ is measureble. Let $$A = \int_Xf\ d\mu$$  Show that  $$ \sqrt{1+A^2} \ \le \  \int_X\sqrt{x+f^2}\ d\mu \ \le \ 1+A $$  The first equality seems obvious but I don't know how to officially prove and I'm completely stuck with the second equality. Any help would be appreciated!

I've been learning about $L^p$-spaces and came across this problem in Rudin's Real and Complex Analysis:     Suppose $\mu(\Omega)=1$ and $h:\Omega \to [0,\infty]$ is measurable. If $A= \int_\Omega {h d\mu}$, prove that:   $$ \sqrt{1+A^2} \leq \int_\Omega \sqrt{1+h^2}d\mu \leq 1+A $$   I've already shown that $\sqrt{1+A^2} \leq \int_\Omega \sqrt{1+h^2}d\mu$ using Jensen's inequality applied to the convex function $\varphi(x)=\sqrt{1+x^2}$. I can't seem to show the latter inequality. Any help or hints would be appreciated. Thank you in advance!


A discussion arose in  about how rare it was for witches/ wizards to get into relationships with Muggles.  I was under the impression that it was fairly common, as I could immediately bring to mind at least three people who were conceived of this type of relationship:   Dean Thomas Severus Snape Tom Riddle (Voldemort)   Are there many other wizards/ witches in canon who had relationships/ marriages/ families with Muggles? (Not including squibs).

As part of my digging into heritability of magic, I am trying to see if there's any difference between the chances of being a wizard with one Muggle parent if your mother vs. your father was a Muggle.  As far as I know, JKR didn't cover that explicitly, but we can at least make a guess based on statistics.  As such: Of all the half-Muggles mentioned by JKR (books, supplemental books, interviews, Pottermore) where we know who was a Muggle among parents, how many were Muggle fathers vs Muggle mothers?  To avoid creating an endless list of answers, if you can think of another example that wasn't tallied before, please edit it into an existing answer.  NOTE: this question uses "half-Muggles" instead of JKR's term "half-blood" because I only care about kids whose one parent was a Muggle; whereas in Potterverse, the "half-blood" term also applies to those whose second parent was Muggle-born magic user (such as Harry Potter).


Which of these two sets of examples are more correct?     Finally, I decided to not go to the party.   Finally, I decided not to go to the party.          Tell your sister not to worry about the exam.   Tell your sister to not worry about the exam.

This is one thing that keeps bugging me, and maybe there's a direct answer. Grammatically, which one is more correct of these two?  Does it make a difference?  I tried not to do that. I tried to not do that.


I've successfully installed Ubuntu (or so I'm told) on my Dell laptop alongside a clean Windows XP install. When I turn on the computer it boots directly into Windows with no options given to boot into Linux. What am I missing?

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


I have an Indian Passport and am travelling from Berlin to Dubai with Turkish airlines and have to change the airports in turkey. Do I need a visa for that?

I have an Indian passport and am planning to visit Germany with a valid visa. To book a flight for Germany (Mumbai – Dusseldorf), I came across some connected flights that stop at Istanbul.  Do I need to have visa for Turkey?  This is the first time I am travelling outside my country, and any information on this will be helpful.


Let $A=$ $\{$ $(x_1,x_2,x_3....)$: $x_i\in \mathbb{Q}$ $\forall i$ and $\exists$ $k>0$ such that $l>k$ $\implies$ $x_{l}=x_{l+1}$ $\}$  Show that the set is countably infinite.  I'm not sure how to do this, may someone help? I'm not sure where to start as well.

On the one hand concatenation of the finite sequence produces a set that is a subset of the natural numbers. On the other hand, while Cantor's diagonal argument fails to produce a sequence with trailing zeros (at the same time not on the list)--I was wondering if there is a way to salvage the diagonal argument?


I am using centos7 locally. Mistaken I deleted text file(keystone.conf.disabled) using rm, from /etc/httpd/conf.d directory, How to recover this file. This file is very important to me. Please help me..  I try to but in vain It is giving message Filesystem n  [vagrant@localhost conf.d]$ debugfs -w /dev/mapper/wks01-root debugfs 1.42.9 (28-Dec-2013) /dev/mapper/wks01-root: No such file or directory while opening filesystem debugfs:  lsdel lsdel: Filesystem not open debugfs:     I try also using as root user  [vagrant@localhost conf.d]$ su Password:  [root@localhost conf.d]# debugfs -w /dev/mapper/wks01-root debugfs 1.42.9 (28-Dec-2013) /dev/mapper/wks01-root: No such file or directory while opening filesystem debugfs:  lsdel lsdel: Filesystem not open debugfs:

Is there a command to recover/undelete deleted files by rm?  $ rm -rf /path/to/myfile   How can I recover myfile? If there is such a tool how can I use it?


Can we also assign a subnet to a computer as an ip address?

If it's subnet then it should have 254 hosts. But it's showing me that it's my private ip address of my linux VM but it looks like subnet. If i use ip addr command it shows my ip is 10.0.1.178/24 as show below but if i use ifconfig command it show my ipaddres is 10.0.1.178 as show below Output of ip addr eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 qdisc fq_codel state UP group default qlen 1000     link/ether 02:e4:6b:7e:e5:ea brd ff:ff:ff:ff:ff:ff     inet 10.0.1.178/24 brd 10.0.1.255 scope global dynamic eth0        valid_lft 1928sec preferred_lft 1928sec     inet6 fe80::e4:6bff:fe7e:e5ea/64 scope link         valid_lft forever preferred_lft forever  Output of ifconfig eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9001         inet 10.0.1.178  netmask 255.255.255.0  broadcast 10.0.1.255         inet6 fe80::e4:6bff:fe7e:e5ea  prefixlen 64  scopeid 0x20<link>         ether 02:e4:6b:7e:e5:ea  txqueuelen 1000  (Ethernet)         RX packets 782364  bytes 646522004 (646.5 MB)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 363184  bytes 42400501 (42.4 MB)


I wonder how to solve this problem using mathematical induction: $1 + \frac{1}{\sqrt{2}} + \frac{1}{\sqrt{3}} + ... + \frac{1}{\sqrt{n}} > \sqrt{n}, n\geq2$ I showed true for $n = 2$ Assumed true for $n = k$, the tried to prove true for $n = k + 1$, but I was unable to finish proof. How should I prove this inequality correctly?

I am just starting out learning mathematical induction and I got this homework question to prove with induction but I am not managing.  $$\sum\limits_{k=1}^{n}{\frac{1}{\sqrt{k}}\ge\sqrt{n}}$$  Perhaps someone can help me out I don't understand how to move forward from here: $$\sum\limits_{k=1}^{n+1}{\frac{1}{\sqrt{k}}+\frac{1}{\sqrt{n+1}}\ge \sqrt{n+1}}$$ proof and explanation would greatly be appreciated :) Thanks :)  EDIT sorry meant GE not = fixed :)


Let $\phi:A\rightarrow B$ be a ring homomorphism. Let $X＝ \operatorname{Spec}(A)$, $Y= \operatorname{Spec}(B)$. If $q\in Y$, then $\phi^{-1}(q)$ is a prime ideal of $A$. Hence $\phi$ induces a mapping $\phi^* :Y\rightarrow X$. Show that:       If $b$ is an ideal of $B$, then    $$\overline{\phi^*(V(b))}＝V(b^c).$$   Here $b^c$ is the ideal $\phi^{-1}(b)$.    I can prove that the left side is contained in the right side. But I can't prove the right side is contained in the left side.

The following is exercise I.21.(iii) of Atiyah-Macdonald:     Let $\phi \colon A \to B$ be a ring homomorphisms. Let $X = \operatorname{Spec} A$ and $Y = \operatorname{Spec} B$ [and let $\phi^\ast \colon Y \to X$ be the induced mapping, $\phi^\ast (\mathfrak q) = \phi^{-1} (\mathfrak q)$]. Show that   [...]   iii) If $\mathfrak b$ is an ideal of $B$, then $\overline{\phi^\ast (V (\mathfrak b))} = V (\mathfrak b^c)$.   [...]   After trying myself for a while, I looked at solutions posted on the internet, one of which presented the following solution.     It is clear that $\mathfrak p \in \overline{\phi^\ast (V (\mathfrak b))} \color{blue} \Leftrightarrow r (V (\mathfrak b)^c) \subset \mathfrak p$ and $\mathfrak p \in V (\mathfrak b^c) \Leftrightarrow \mathfrak b^c \subset \mathfrak p$. Then it suffices to show that $\mathfrak b^c \subset \mathfrak p$ if and only if $r(V (\mathfrak b)^c) \subset \mathfrak p$, which is true because $r(V (\mathfrak b)^c) = r(V (\mathfrak b))^c \color{blue} = r(\mathfrak b)^c = r(\mathfrak b^c)$.   where I have marked the things I don't understand in blue.  In the meanwhile I have found a different proof for the exercise, but I still don't understand this proof. In particular   I don't understand the connection between taking the closure and taking the radical. I don't know if $r(V (\mathfrak b)^c)$ is a shorthand for the set of elements contained in the contractions of prime ideals contained $\mathfrak b$ or for the ideal generated by these elements or something else. I don't see why the marked equality holds.


I wrote a class file, but I found if I want to change the space between the math environment and text by the , the indentation appears in front of the 'abstract'. Here is the mwe,              \begin{filecontents}{mycls.cls}             \NeedsTeXFormat{LaTeX2e}             \ProvidesClass{mycls}             \LoadClass{article}             \newdimen\@bls             \@bls=\baselineskip             \renewcommand\section{\@startsection {section}{1}{\z@}%                                    {1.2\@bls  plus .3\@bls minus .1\@bls}%                                    {5pt\@afterindentfalse}%                                    {\sffamily\large\bfseries\raggedright}}             \newbox\absbox             \def\abstract{\lrbox\absbox\minipage{\textwidth}%             \sffamily%             \hspace{-\fill}\section*{\normalsize\noindent Abstract}\vskip -1.5mm\relax%             }             \def\endabstract{\endminipage\endlrbox}              \def\keywords#1{%             \gdef\@keywords{\begin{minipage}{\textwidth}{\normalsize\sffamily \textbf{Keywords}}\\ \parbox[t]{\textwidth}{#1}\end{minipage}}}             \let\@keywords\@empty              \def\@maketitle{{\noindent\usebox\absbox\par}             {\vspace{20pt}%             {\noindent\normalsize\@keywords}\par}{\vskip2em\relax}}             \end{filecontents}             \documentclass{mycls}             \usepackage{lipsum}             \begin{abstract}             \lipsum[1]             \end{abstract}             \keywords{Hello}             \begin{document}             \maketitle             \lipsum[1]             \begin{equation}\label{eq:test}             a^2+b^2=c^2             \end{equation}             \lipsum[1]             \end{document}    The class and code above gives    But if I add the code              \expandafter\def\expandafter\normalsize\expandafter{%                 \normalsize                 \setlength\abovedisplayskip{40pt}                 \setlength\belowdisplayskip{40pt}                 \setlength\abovedisplayshortskip{40pt}                 \setlength\belowdisplayshortskip{40pt}             }   in the class file, the output will be    Some space appears in front of the 'abstract' and 'keywords'.  I want to know where the space comes from and how to cancel it.

I have  experience where empty spaces cause unwanted effects. It is not easy to trace the cause of these unwanted effects. In order to eliminate any doubt, I often overuse % as follows.   \usepackage% [% left=3cm, right=3cm% ]% {geometry}   or  \newcommand{\mycommand}% {% This is my command.% }   I got an extreme example that will break what Leo Liu said     In fact, only spaces which would be   output have to be removed by comment.   The following code does not produce output, but we cannot remove the % and leave a blank line between two elements of a list below.  \newpsstyle{gridstyle} { gridwidth=0.4pt, % griddots=0 }   Shortly speaking, where are the necessary places to be appended with % to remove unwanted spaces?


Upgraded the os last night and this afternoon my settings and safari icons disappeared.  help!!  how do I get them back?

I updated to High Sierra on my Macbook Pro when it was released. Since I have updated, a lot of my applications show the attached icon when I open them. Does anyone know a fix to this?


For example you have a HashMap<String, String>  how can you sort values in the hashmap and print them to console  what would be the best ways to do it?

I am relatively new to Java, and often find that I need to sort a Map<Key, Value> on the values.  Since the values are not unique, I find myself converting the keySet into an array, and sorting that array through array sort with a custom comparator that sorts on the value associated with the key.  Is there an easier way?


I am currently using  to check for rootkits on my MacBook. Does anyone know of a more efficient piece of software to run rootkit checks on MacBooks and macOS?

I'm looking at buying a second-hand Mac, probably one that does not include an OS installation disk.  How can I scan it to make sure that it has not had security threats installed on it?  Is there a CD or DVD image I can boot it up with to perform this scan offline?  Edit: prospective machine would be a 2011- or 2012-vintage MacBook Pro.  Also note that I don't have reliable access to high-speed internet, so solutions that involve downloading 5GB over the Internet are not ideal.  For others, though,  may be helpful.


I have some CSV files that need to be converted to ESRI shapefile. These files are built like explained in the section "Building line geometries" from the . For example one file can be like this:  > head river_xy2.csv                                                                                way_id,pt_id,x,y 1,1,11.836,44.829 1,2,11.827,44.829 1,3,11.818,44.829 1,4,11.809,44.838 1,5,11.8,44.847 1,6,11.791,44.856 1,7,11.782,44.856 1,8,11.773,44.856 1,9,11.764,44.856   GDAL understands this, for example I can do:  ogrinfo river_xy2.csv -dialect SQLite -sql "SELECT way_id, MakeLine(MakePoint(CAST(x AS float),CAST(y AS float))) FROM river_xy2 GROUP BY way_id"   And I get a nice list of OGRFeatures in output. However, how can I save that to a shapefile? If I try to use GDAL_translate:  > gdal_translate -of "ESRI Shapefile" -a_srs EPSG:4326 river_xy2.csv river_xy2.shp ERROR 4: `river_xy2.csv' not recognized as a supported file format.   While if I remove the first row I get an error after the first feature:  ERROR 1: Ungridded dataset: At line 549, change of Y direction   EDIT: It looks like I can do:  ogr2ogr -dialect SQLite -sql "SELECT way_id, MakeLine(MakePoint(CAST(x AS float),CAST(y AS float))) FROM river_xy GROUP BY way_id" -a_srs EPSG:4326 river_xy.shp river_xy.csv


I see somewhere that the value of the integral $$ I(\alpha)=\int_0^\infty \frac{1}{(1+x^2)(1+x^\alpha)} \mathbb dx,\alpha\in \mathbb R^+ $$ does not depend on $\alpha$. So $I=\pi/4$ for all $\alpha$. How can I prove this?  I tackled the special case $\alpha=2$ quite easily by contour integration, but find it quite awkward to deal with general $\alpha$. Contour integration doesn't seem to work for $\alpha=\sqrt 2$, for example.  I tried $dI/d\alpha$ and $I(\alpha)-I(\beta)$, but both lead to very complicated functions that don't lead to anywhere.

Let $a$ be a non-zero real number. Is it true that the value of $$\int\limits_0^\infty \frac{\mathrm{d} x}{(1+x^2)(1+x^a)}$$  is independent on $a$?


In the answer to  Ittay Weiss wrote that, "...a sum of infinitely many positive elements can be bounded only if there are countably many elements." Though I asked about a rigorous proof of this fact and a reply was given, as can be easily seen, I still have some doubts which I need to clarify. I also didn't understand how Weiss's comment gives a proof of my question and so I am asking it here again.   It seems from the phrasing of the quote that there are other types of sum of positive elements for which the number of elements isn't countably infinite. What are some examples of sums of this type? To be precise, if sum of positive elements for which the number of elements isn't countably infinite then should it be necessarily uncountable?  If so, then how do we define a "sum" of uncountable number of positive quantities?  What is meant when we say that the "sum" is unbounded?  Why is a sum of infinitely many positive elements can be bounded only if there are countably many elements?    Any help will be appreciated.

Claim: If $(x_\alpha)_{\alpha\in A}$ is a collection of real numbers $x_\alpha\in [0,\infty]$ such that $\sum_{\alpha\in A}x_\alpha<\infty$, then $x_\alpha=0$ for all but at most countably many $\alpha\in A$ ($A$ need not be countable).  Proof: Let $\sum_{\alpha\in A}x_\alpha=M<\infty$. Consider $S_n=\{\alpha\in A \mid x_\alpha>1/n\}$.  Then $M\geq\sum_{\alpha\in S_n}x_\alpha>\sum_{\alpha\in S_n}1/n=\frac{N}{n}$, where $N\in\mathbb{N}\cup\{\infty\}$ is the number of elements in $S_n$.  Thus $S_n$ has at most $Mn$ elements.   Hence $\{\alpha\in A \mid x_\alpha>0\}=\bigcup_{n\in\mathbb{N}}S_n$ is countable as the countable union of finite sets. $\square$  First, is my proof correct? Second, are there more concise/elegant proofs?


I am hoping for a problem I am working on that the function defined above is an isomorphism of groups, but I cannot manage to prove it. Is $[a \cdot \sigma] = [a \cdot id: \Delta^n \to \Delta^n]$ for any $\sigma: \Delta^n \to \Delta^n$?

The homomorphism $a \mapsto [[a \cdot f]]$ is supposed to be an isomorphism between $A$ and $H_n(D^n, S^{n - 1};A)$ for any homeomorphism $f: \Delta^n \to D^n$. I have proven that it is well defined and injective, but why is it surjective?  The group $H_n(D^n, S^{n - 1};A)$ is generated by elements of the form $a \cdot \sigma + b \cdot \tau + c \cdot \partial(\kappa)$ where $\sigma: \Delta^n \to D^n$, $\tau: \Delta^n \to S^{n - 1}$ and $\kappa: \Delta^{n + 1} \to D^{n + 1}$ and I do not see how an element of this form represents the same equivalence class of $[[m \cdot f]]$ for some $m \in A$. We can write $\sigma$ as $f f^{-1} \sigma$ to get $f$ in there, but I don't see that working out. Any hints?


I'm trying to start a number of threads at the same time but it is not working. Heres my code:           var previous = 0;          var threadList = new List<Thread> {};         for (var i = (int)partSize; i <= responseLength; i = i + (int)partSize)         {             var t = new Thread(() => Download(URL, previous, i));             //t.Name = i.ToString();             threadList.Add(t);             //t.Start();             //t.Join(300);             //new Thread(() => {Download(URL,previous, i);}).Start();             //var t = Task.Factory.StartNew(() => Download(URL, previous, i));              previous = i;         }          foreach (Thread t in threadList)         {             //Console.WriteLine(t.Name);             t.Start();         }   OUTPUT:  77296,86958 77296,86958 77296,86958 77296,86958 77296,86958 77296,86958 77296,86958 77296,86958   After displaying this for a while, it hangs up and eventually crashes.   Expected output with different code:          for (var i = (int)partSize; i <= responseLength; i = i + (int)partSize)         {             var copy = previous;             var t = new Thread(() => Download(URL, copy, i));             t.Start();             t.Join();              previous = i;         }   OUTPUT:  0,9662 9662,19324 19324,28986 28986,38648 38648,48310 48310,57972 57972,67634 67634,77296   As for the output the first number indicates where to start downloading a piece of a file and the second number indicates where to finish (in bytes) How can I start every thread in the list, with the parameters I am assigning to it? I am lost, so any help would be awesome. Thanks!

I met an interesting issue about C#. I have code like below.  List<Func<int>> actions = new List<Func<int>>();  int variable = 0; while (variable < 5) {     actions.Add(() => variable * 2);     ++ variable; }  foreach (var act in actions) {     Console.WriteLine(act.Invoke()); }   I expect it to output 0, 2, 4, 6, 8. However, it actually outputs five 10s.  It seems that it is due to all actions referring to one captured variable. As a result, when they get invoked, they all have same output.  Is there a way to work round this limit to have each action instance have its own captured variable?


I could not find the meta of Web Applications. It should have been easier to find (I did not find it actually, I just added "meta" to the URL).

How do you expect users to:   Know that a site's meta-site exists (and what it's for)? Find the hyperlink to the meta-site?   I know it exists, of course, and how to get there; I'm wondering how (or even whether) you expect new or naive users to do that.  I think there isn't a link to Meta from the main site, am I right (except one link in the "list of all 171 Stack Exchange sites" drop-down menu on the toolbar)?  Sometimes I tell people to post a question on Meta instead of on the main site -- I don't realise that they may not know that Meta exists, and that if they do (because they've been there before) they don't know how to get there (because they haven't yet investigated everything on the toolbar).


I have an android phone which shows a peculiar icon on top right corner of the screen (notification area):  I believe: Icon number 1 is for signal Icon number 3 is for wifi Icon number 4 is for battery.  What does icon number 2 indicate? I could not find it on searching the net. Thanks for your help.

After I factory reset my Nokia 6, this icon appeared. I've never seen it before. What is this icon in the highlighted part?


here is how it looks. I was modelling on solid view. I switched to Material view and now the models are not visible in the wireframe and solid view.

When looking at my objects in 3d view I'm seeing a gray cone that seems to be hiding other objects.   Can anyone help me turn this off and explain what it is please.  Screenshots attached.


I have a form where i attach the OnChange method like  $(document).ready(function () {     $('#fieldId').change(function () {     ...    } }   But i have the case when i add a new record with the Id "fieldId" from a function as   function addTeamMember() { var newItem= "<input  id='fieldId' type='text'>" $("#other").append(newItem); ... }   But the Change is not fired when i change the newly added field. Can somebody help me with an idea?  Thanks.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


It'd be extremely handy if we were able to paste images directly into the post textarea (both from photos saved on my iPhone, and photos from other websites, if there's any difference).   I'd expect this action would upload the image to i.stack.imgur.com, and the markdown for the image inserted into the cursor position.   Currently, it's a bit of a faf to go to the full website view on a browser, upload the image, then return to the mobile app to insert the markdown yourself.

So this is pretty obvious. Image upload?    How about allowing to attach images in questions from the photo gallery, by perhaps sending the image for off-site storage like done from the full-web version?


I have a Lenovo Ideapad A10 Android 4.2.2 netbook with a Rockchip RK3188 processor. The Rockchip RK3188 is a fast ARM SoC primarily designed for tablets. Unfortunately I soft bricked it and I wasn't unable to flash a recovery firmware since Lenovo does not support the device or maybe the developers are too lazy to create a recovery image for the device. Anyway I'm asking if I can install Ubuntu onto the device's internal storage?  I was able to run Slackware from the external SD card, but somehow it's quite buggy. I cannot install picuntu on it, and I think Lenovo does not allow it or there are some other reasons behind it.

I have a device on which I would like to install Ubuntu. How do I find out if Ubuntu will work on it?


This question is from Gallian Page 69 Q 9. Suppose a subgroup od D_4 contains H and D. I want to show that these two generated whole of $D_4$. Now rotation will generate other rotations which is fairly clear. But i am confused about how reflections can generate other reflections? Because a reflection say V will, if applied again and again can generate only V and identity which is $R_0$ but how do other reflections can be generated by this  Thanks a lot

Let be $D_n$ the group of symmetries of a regular n-sided polygon. Prove that $D_n$ is generated by a minimum rotation angle and a reflection (about a symmetry axis).  I really do not know how to start . Some help plis


Show that the polynomial $x^2+y^2-1$ is irreducible over $\mathbb{Q}[x,y]$.    Theorem : Let $A$ an integral domain and $I$ a proper ideal of $A$. If $f(x) \not \equiv a(x)b(x) \pmod I$ for any polynomials $a(x)$, $b(x)$ $\in A[x]$ of degree $\in [1, \deg(f))$, then $f(x)$ is irreducible in $A[x]$  I think I have to use this theorem, maybe in using the ideal $(y^2)$  The fact that $\mathbb{Q}[x,y]=\mathbb{Q}[x][y]$ and $\mathbb{\mathbb{Q}[y]}$ is a unique factorization domain could it help me here? Is anyone could help me at this point?

How can I prove that $\mathbb{Q}[x,y]/\langle x^2+y^2-1 \rangle$ is an integral domain?  Also, I need to prove that its field of fractions is isomorphic to the field of rational functions $\mathbb{Q}(t)$?    (The question is taken from )


The dragon ball super anime started last week.  I'm wondering when this takes place. I know it takes place after the defeat of buu, like a few months or something.  But with the releases of the movies I'm wondering where does those fit in? Can anybody answer me this?

At the end of the Dragon Ball series we can see . There had been years of peace so we see Goten and Trunks all grown to teenagers, yet in the Super series they are still young. So it seems that Uub does not exist yet and the Super series does not follow directly after the Dragon Ball series, the same way the GT series did. So where does it fit in? When does the Super series take place?


Let's say I am using the hyperref package, which automatically hyperlinks eqref, cite, etc.   I know its a stretch, but has anyone ever encountered a PDF viewer (I'm very happy with Sumatra) that can show a small balloon when I hover over such a link, that shows the linked equation or bibliography item? Instead of having to click on it and jump to the correct page.

This idea came into my mind while I was listening to a speaker presenting his results in a seminar, he used lots of equation references in his later slides, however I can't remember which equation he was referencing to for he gave several models during an earlier stage of the presentation.   We could use hyperref to get hyperlinks on the \eqref, but clicking it would go back to the original page where the equation was labeled, and somehow interrupt the presentation.  I have several workarounds in mind: (1) exploit the \pause option as the overlay, once hitting space, the referenced equation would show. (2) use tikz to insert a minipage into the frame that contains the referenced equation.  However, both solutions require the referenced equation taking up spaces in the current slide the presenter is on, the best solution is still I said in the question title: mouse over the \eqref number, then a comment popping up showing the equation.  My google-fu leads me to a package called comment, however I didn't find any nice examples of how to use that package to produce beautiful slides.  Hence I wonder is it possible to produce some mouseover events like the title said, or any other workarounds are welcome too.


"Given an associative F-algebra do there necessarily exist elements a1.a2∈K satisfying a1∗a2=a?"  I have a question to add to the one linked below:    My question:  Will there always exist a1,a2∈K satisfying a1∗a2=a? I thought for F-algebra "*" didn't necessarily have an identity element, or associativity.  I know it tells us we have an associative F-algebra, but why do those elements 'have' to exist?  There were 2 instances mentioned where they do exist, but I am wondering if they 'have to exist.'  I may just be paying too much attention to one word, but I want to make sure I understand the subject.  Thanks!

Let $F$ be a field and let $(K,*)$ be an associative $F$-algebra which, as a vector space, is finitely generated over $F$. Given an element $a\in K$, do there necessarily exist elements $a_1,a_2 \in K$ satisfying $a_1*a_2=a$?  I'm not sure how to go about this. Since we have an associative $F$-algebra we know that $v*(w*y)=(v*w)*y$ for all $v,w,y \in K$.


According to "" you can stack their use to increase an ability score multiple times, even beyond 20.  So in theory, you can increase an ability score as much as you like. What practical limitations are there, if any, that would prevent a high-level character from getting an arbitrarily-high ability score via Tomes or Manuals?  In earlier editions I could point to hard limits to deal with munchkins wanting to exploit these, and I'm concerned by the lack of any obvious limit I can point at to stonewall them in 5e.

I am looking at items like Manual of Bodily Health, Tome of Clear Thought, etc.  Quoting from Manual of Bodily Health     If you spend 48 hours ... your Constitution score increases by 2, as   does your maximum for that score.   This sounds to me like when you read the tome according to the instructions, you are then allowed to increase your CON up to a maximum of 22.     Is that a correct reading -- that these magic items allow a player to override the usual ability score maximum of 20? Probably, you were already at 20 when you read it, but if, say, you were at 18 and read it to bring your CON up to 20, could you then later increase your CON further via feats or ability score increases gained at certain levels? Can you read more than one book of the same type, to increase your maximum by an additional 2 points?


I am currently struggling to get my head around what eigenvalues and eigenvectors truly are as Khan Academy says that eigenvalues are just a scalar by which a vector is scaled and the eigenvector is the resultant vector that is not equal to zero, but other sources say different things.   I was wondering whether someone would be able to provide a simple explanation of what eigenvalues and eigenvectors are, and it would be greatly appreciated if a visual supplement is provided. I need to learn these to find the general solution to a markov matrix and am becoming quite confused.   Thanks!

Been browsing around here for quite a while, and finally took the plunge and signed up.   I've started my mathematics major, and am taking a course in Linear Algebra. While I seem to be doing rather well in all the topics covered, such as vectors and matrix manipulation, I am having some trouble understanding the meaning of eigenvalues and eigenvectors.  For the life of me, I just cannot wrap my head around any textbook explanation (and I've tried three!), and Google so far just hasn't helped me at all. All I see are problem questions, but no real explanation (and even then most of those are hard to grasp).  Could someone be so kind and provide a layman explanation of these terms, and work me through an example? Nothing too hard, seeing as I'm a first year student.  Thank you, and I look forward to spending even more time on here!


Previous post     As hopefully most moderators are aware, we've been working over the last few months to revamp the moderator flag dashboard.  After running a small and then wide alpha, collecting and addressing plenty of feedback along the way, we're officially launching the new design mostly. Mostly? We like the new design, we think it makes more sense, will be easier to build on, and is just more pleasant.  That said, today might not be the day for you to try a new moderating tool.  You may be under a spam attack or cleaning up a bunch of nasty comments from someone's unfriendly bot and a sudden change could mess everything up.  For the next few weeks, you will be able to use the old UI by deselecting the "Admin Dashboard Refresh" checkbox on your site's /users/preferences/current. But please don't unless you have to, and please switch back when you have the bandwidth.  The new dashboard is the shipped product, and the old one won't stick around forever - if something's blocking you from using it, we need to address that not ignore it! What's new?  Old UI  New UI   As described in the alpha phase announcement post:  Beyond appearances, there have been some thoughtful reworks:  More / clearer context for flags (e.g., edited-after-flag indicator, post owner indicator). Consistent location and ordering for actions on posts, flags, and comments (making muscle memory matter!) Comment editing, move comments to chat works the same in the dashboard and on the question page. The flag "waffle bar" stays better in sync with changes happening the page and vice versa. Same with actions taken inside embedded posts. Responsive design for phones and tablets. Previously undiscoverable UI components are now actual buttons. "No further action" has been brought inline with the page. Smaller quality-of-life improvements along the way.   There are some additional improvements over what shipped last month:  Less content shifting to minimize mouse movement when handling comment flags. Less information overload. Flagged answers are treated as the primary UI element rather than their parent question.  (Less question information, links go to answer.) Auto-flags don't have the long unneeded dismiss UI. Previously viewed posts are less faded and should be easier to read without hovering over them. Various bug fixes and design tweaks.  A special note for international site mods I've reached out to the international team with the (mostly accurate) list of recently introduced strings that need to be translated for this feature.  The strings and hashes are available in . Next steps At the end of July 2019, we will review feedback we receive and run additional rounds of interviews. After this, we expect to share an updated timeline on when the legacy UI will be decommissioned. If everything is relatively minor, we would aim to turn it off as early as early August. Bugs and Feature Requests Since we are officially out of alpha, all bugs and feature requests should be done in the form of questions tagged  on MSE, not answers on this post.  Feel free to post an answer here if you have specific concerns about the release process.

Previous posts                  As of today, the Moderator Flag Dashboard is officially graduated and the old version sent to the smelter's yard.  Based on stats from the past month, virtually all moderators were already on the new UI (thank you) so you hopefully won't notice any change.  That said, I would like to highlight the handful of improvements we made over the last month and a half based on your feedback:   A more responsive navigation bar at the top of moderator pages, improving the mobile experience. Similarly, , increasing room on the screen for the first question. . .  Not only do the headers look better, they now function better.  Now you scroll to and highlight the post/comment each time you click the link, not just the first time. .  Posts by the same user are grouped together and ordered newest first. .  We eliminated the VLQ (auto) side effect so now "Resolve all flags (auto)" doesn't do anything surprising.  If you still want to leave a comment or decline, you can do so with the buttons next to the individual flags.   Bugs and Feature Requests  Since this project is officially launched, all bugs and feature requests should be done in the form of questions tagged  on MSE, not answers on this post.  Feel free to post an answer here if you have specific concerns about the release process.


OS: Ubuntu 16.04  I've looked at a lot of different articles and threads, and I still can't get my cron.hourly jobs to run automatically. I am trying to run a backup on my PostgreSQL database. In /etc/cron.hourly, I have only one script named pg_backup. Here are the permissions on it:  -rwxr-xr-x   1 root root  1543 Oct 16 19:07 pg_backup   If I run run-parts --test /etc/cron.hourly, the output is as follows:     /etc/cron.hourly//pg_backup   That looks good. If I run the script using run-parts manually, it works as expected and backs up my database. Here's the command I'm using:  run-parts -v --report /etc/cron.hourly  That's great, but for whatever reason, it's not running every hour by itself. I really don't know what could be wrong. I've checked all the logs and haven't been able to find any error messages.  What am I missing?  UPDATE  I noticed that my /etc/crontab file has the shell specified like so: SHELL=/bin/sh. My script runs in bash. Is it sufficient to have the shebang at the top of my script for it to use bash? #!/bin/bash  UPDATE 2  As suggested by Broco, I put the job in my crontab, and it's still not working. Here's what I did:  sudo crontab -e  Then I added the following to the file:  * * * * * root /etc/cron.hourly/pg_backup  I made it run every minute to get quicker feedback on whether or not it's running, and it seems to be running but isn't actually performing the backup.  Here's part of my syslog. I used the command grep CRON /var/log/syslog:  Oct 17 14:02:01 User CRON[63871]: (root) CMD (root /etc/cron.hourly/pg_backup) Oct 17 14:02:01 User CRON[63870]: (CRON) info (No MTA installed, discarding output) Oct 17 14:03:01 User CRON[63917]: (root) CMD (root /etc/cron.hourly/pg_backup) Oct 17 14:03:01 User CRON[63916]: (CRON) info (No MTA installed, discarding output) Oct 17 14:04:01 User CRON[63966]: (root) CMD (root /etc/cron.hourly/pg_backup) Oct 17 14:04:01 User CRON[63965]: (CRON) info (No MTA installed, discarding output) Oct 17 14:05:01 User CRON[64013]: (root) CMD (root /etc/cron.hourly/pg_backup) Oct 17 14:05:01 User CRON[64012]: (CRON) info (No MTA installed, discarding output) Oct 17 14:05:01 User CRON[64014]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1) Oct 17 14:06:01 User CRON[64060]: (root) CMD (root /etc/cron.hourly/pg_backup) Oct 17 14:06:01 User CRON[64059]: (CRON) info (No MTA installed, discarding output) Oct 17 14:07:01 User CRON[64106]: (root) CMD (root /etc/cron.hourly/pg_backup) Oct 17 14:07:01 User CRON[64105]: (CRON) info (No MTA installed, discarding output)

This is a  about using cron & crontab.   You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you gather information that will help the community help you. This information should be edited into your original question.  The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below.  This addresses the cron system with the crontab highlighted.


I got signed out of Pokemon go and when I logged back on it had a whole new account, Ive realised Its not actually giving me the option to sign in, only sign up? Does anyone know how I can get the option to sign in back? I've tried deleting the app and redownloading it, turning the phone off etc, I can't work it out! I have it on iPhone with all the latest updates working   Thanks in advance

I just updated the Pokemon go app and it asked me to log in again and I'm back at the very start, please help!


Does anyone know a good book about generalized linear models. I am a practitioner and need to master the concepts of generalized linear model, but also my experience tells me that knowing about the background math equations will also be a great help. So to sum it up I am looking for a book (or books) which gives a great intuition about the concepts and also I am looking for a book which explains the equations from A to Z. Below I have written my agenda from most important to least. Please if you know a good reference for each, tell me. Thanx   Generalized linear models' concepts Generalized linear models' equations Alternatives for logistic regression for correlated data (equations, concepts and everything!)

Is there consensus in the field of statistics that one book is the absolute best source and completely covering every aspect of GLM - detailing everything from estimation to inference?