I have been using a WD external drive for a couple of years with no problems but now I can not read it. The light is on when connected to the laptop, it does the useual  flashing light and you can feel feel the disc rotating but that is it.  In windows explorer it shows the drive (F:) but will not show what is on the drive. Clicking on the drive brings up a warning message - Windows explorer not responding.  This happens to all programs used to try and access the data on the drive, office programs etc. Including EaseUS and Data lifeguard for windows. WD drive utilities program does not even recognize it is connected. Using the Data lifeguard software, this carries out an analysis of drive and then disappears as it shut down. Checking with task manager it does not show it as running but remove the WD drive from the USB port the lifeguard program appears showing the details if the laptop internal drive.  Any one with any idea with what may have cased the issue and what can be done to rectify?

What steps can I take to try to recover lost or inaccessible data from any storage device?  Answers:   This applies to any computer storage device, e.g. internal/external hard drives, USB sticks, flash memory. The most important thing is to STOP using it, any type of I/O can ruin your chances of a recovery.     We have separate questions covering common problems with USB flash drives in greater detail:


After a question get closed, it can be reopened after it was substantially enhanced.   But it may be substantially enhanced while it has one or more close votes, but not closed yet.  I think it should be possible to get the close votes removed in case there is a majority that it should be reopened if it were closed. Some close votes mean a question is only partially closed. Now, few or just one vote could close it. I think partly closing should be reverted if it would be voted to reopen when completely closed.   Is this possible? If not, is it a helpful feature?

My request is simple: Many times, there will be a question where some people feel like it should be closed. At the same time, I'll feel like it's a perfectly legit question, and it should therefore NOT be closed. Right now, I have to wait till it gets enough close votes (which it always does for some reason, as soon as 1 or 2 people vote to close, e/o else decides to vote as well) and then vote to re-open. How about, as soon as there's one vote to close, there should be an option to counter the close vote, something like "vote not to close" or whatever. This would then bring the "Vote to close" number down by one. Only when the vote to close outnumbers the vote not to close by 5, that's when a question is indeed closed. Any thoughts?


How to redirect every vhost to https but without duplicating configuration. I have 4 websites on the same vps running Nginx and I want to redirect everything to https.

There appear to be many questions and guides out there that instruct how to setup nginx to redirect http requests to https. Many are outdated, or just flat out wrong.   # MANAGED BY PUPPET  upstream gitlab {   server unix:/home/git/gitlab/tmp/sockets/gitlab.socket; }  # setup server with or without https depending on gitlab::gitlab_ssl variable server {   listen *:80;   server_name gitlab.localdomain;   server_tokens off;   root /nowhere;   rewrite ^ https://$server_name$request_uri permanent; } server {   listen *:443 ssl default_server;   server_name gitlab.localdomain;   server_tokens off;   root /home/git/gitlab/public;    ssl                           on;   ssl_certificate               /etc/ssl/certs/ssl-cert-snakeoil.pem;   ssl_certificate_key           /etc/ssl/private/ssl-cert-snakeoil.key;   ssl_protocols                 SSLv3 TLSv1 TLSv1.1 TLSv1.2;   ssl_ciphers                   AES:HIGH:!ADH:!MDF;   ssl_prefer_server_ciphers     on;    # individual nginx logs for this gitlab vhost   access_log  /var/log/nginx/gitlab_access.log;   error_log   /var/log/nginx/gitlab_error.log;    location / {     # serve static files from defined root folder;.     # @gitlab is a named location for the upstream fallback, see below     try_files $uri $uri/index.html $uri.html @gitlab;   }    # if a file, which is not found in the root folder is requested,   # then the proxy pass the request to the upsteam (gitlab puma)   location @gitlab {     proxy_read_timeout 300; # https://github.com/gitlabhq/gitlabhq/issues/694     proxy_connect_timeout 300; # https://github.com/gitlabhq/gitlabhq/issues/694     proxy_redirect     off;      proxy_set_header   X-Forwarded-Proto $scheme;     proxy_set_header   X-Forwarded-Ssl   on;      proxy_set_header   Host              $http_host;     proxy_set_header   X-Real-IP         $remote_addr;      proxy_pass http://gitlab;   } }   I've restarted after every configuration change, and yet I still only get the 'Welcome to nginx' page when visiting http://192.168.33.10. whereas https://192.168.33.10 works perfectly.   Why will nginx still not redirect http requests to https?   I've also tried the following configurations      listen *:80;   server_name <%= @fqdn %>;   #root /nowhere;    #rewrite ^ https://$server_name$request_uri? permanent;    #rewrite ^ https://$server_name$request_uri permanent;   #return 301 https://$server_name$request_uri;   #return 301 http://$server_name$request_uri;   #return 301 http://192.168.33.10$request_uri;   return 301 http://$host$request_uri;   The logs   tailf /var/log/nginx/access.log 192.168.33.1 - - [22/Oct/2013:03:41:39 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20100101 Firefox/24.0" 192.168.33.1 - - [22/Oct/2013:03:44:43 +0000] "GET / HTTP/1.1" 200 133 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20100101 Firefox/24.0"  tailf /var/log/nginx/gitlab_error.lob 2013/10/22 02:29:14 [crit] 27226#0: *1 connect() to unix:/home/git/gitlab/tmp/sockets/gitlab.socket failed (2: No such file or directory) while connecting to upstream, client: 192.168.33.1, server: gitlab.localdomain, request: "GET / HTTP/1.1", upstream: "http://unix:/home/git/gitlab/tmp/sockets/gitlab.socket:/", host: "192.168.33.10"   Resources


I use rsync to copy directories including files, with --remove-source-files I let rsync delete source files. Unfortunately it doesn't delete directories so I would like to delete all empty directories under SOURCE1 and SOURCE2. The find -exec rmdir command does this but unfortunately it also deletes the SOURCE directories itself  Copy.sh  SOURCE1="/mnt/download/transmission/complete/" SOURCE2="/mnt/download/sabnzbd/completed/"  sudo rsync --remove-source-files --progress --ignore-existing -vr  /mnt/download/transmission/complete/ /mnt/dune/DuneHDD_1234 sudo rsync --remove-source-files --progress --ignore-existing -vr /mnt/download/sabnzbd/completed/ /mnt/dune/DuneHDD_1234 find $SOURCE1 -not -name "complete" -type d -empty -prune -exec rmdir --ignore-fail-on-non-empty -p \{\} \; find $SOURCE2 -not -name "completed" -type d -empty -prune -exec rmdir --ignore-fail-on-non-empty -p \{\} \;   I also tried the following code  * find $SOURCE1 -mindepth 2 -type d -empty -prune -exec rmdir --ignore-fail-on-non-empty -p \{\} \; find $SOURCE2 -mindepth 2 -type d -empty -prune -exec rmdir --ignore-fail-on-non-empty -p \{\} \;   And without  * find $SOURCE1 -type d -empty -prune -exec rmdir --ignore-fail-on-non-empty -p \{\} \; find $SOURCE2 -type d -empty -prune -exec rmdir --ignore-fail-on-non-empty -p \{\} \;   I could add a mkdir test and change SOURCE1 to "/mnt/download/transmission/complete/test" and this way it always deletes the directory that I just created but I would like to do it the proper way  Example: I created 6 directories:  test10/  test10/test11/  test10/test11/test12/  test10/test11/test12/test  test1/  test1/test2/  test1/test2/test3/  test1/test2/test3/test  After running copy.sh I end up with perfectly copyed directories and files (test1/test2/test3/test and test10/test11/test12/test) on destination and deleted directories and files on source INCLUDING source ($SOURCE1 and $SOURCE2) itself.  Is there a way to tell find to exclude the source directory itself? In other words: Everything UNDER the folowing directories shoud be deleted but not the directories themselves:  SOURCE1="/mnt/download/transmission/complete/" SOURCE2="/mnt/download/sabnzbd/completed/"

Suppose I have a dir tree like this:  ROOTDIR     └--SUBDIR1         └----SUBDIR2             └----SUBDIR3   I am looking for a command such that when I input:  $ [unknown command] ROOTDIR   The whole dir tree can be deleted if there is no file but only dirs inside the whole tree. However, say if there is a file called hello.pdf under SUBDIR1:  ROOTDIR     └--SUBDIR1         └--hello.pdf         └----SUBDIR2             └----SUBDIR3   Then the command must only delete SUBDIR2 and below.


I have a device with multiple USB inputs wired in parallel (Raspberry Pi 2B with Kedei Display, each of the units has an Micro USB input). Are there any dangers of connecting both inputs at once, powered by different powerbanks/chargers? I don't want to do this to increase the supplied current, but rather to swap power supplies without having to turn off the device. So e.g. the connected powerbank is about to run out of power, so I connect a wall charger to the second port and then disconnect the powerbank. Are there any possible negative interactions between the two power supplies? (e.g. different ground potential (especially with two wall chargers), slightly different voltages that cause power to flow in the wrong direction, different voltage fluctuation frequencies from the regulators in the power supplies that cause problems, ...) Related questions While this question seems similar to other questions posted on electronics.stackexchange.com, those questions are quite different in some aspects.   Both of these questions don't actually use different power supplies, but instead multiple ports on the same powerbank. Also both of them do that, to increase supplied current.  This question actually talks about two different power supplies, but also here the idea is to increase current.

I'm designing a board that can be powered either by USB or an ATX power supply.  They can both be plugged in at the same time, independently.  I'd like the ATX to provide 5V if its plugged in, but fall back to the USB if possible.  The chips in the circuit will all be running at 5V.  Any ideas?


I am a Filipina. I booked a tour package with Expat Explore for 10 days tour in Europe. But the start and end point of the tour will be in Greenwich. Basically, I will enter London on June 1, then leave with the tour group to Paris on June 2. Then return to Greenwich on June 11 after the tour.My flight back home will be on June 12. So that means I will enter twice in London.  I want to know if UK Visa is good for multiple entry or single entry only?

I'll be going to UK as sponsored visitor - am I allowed to apply for Multiple visa entry to UK?


I am currently using ubuntu 18.04.I was trying to provide another user sudo permission.After editing visudo ,I can.t fix my sudo...  :~$ sudo /etc/sudoers: syntax error near line 9 sudo: parse error in /etc/sudoers near line 9 sudo: no valid sudoers sources found, quitting sudo: unable to initialize policy plugin riyadh@riyadh-Inspiron-3593:~$

How do I edit an invalid sudoers file? It throws the below error and it's not allowing me to edit again to fix it.  Here is what happens:  $ sudo visudo >>> /etc/sudoers: syntax error near line 28 <<< sudo: parse error in /etc/sudoers near line 28 sudo: no valid sudoers sources found, quitting


How to prevent arp spoofing and mitm attack? I need simple solution. In network we have several workstation, switch and router.

In my campus, some people they are using netcut in Windows and they are blocking us not to use Internet.  Since I am a Ubuntu user, I can't install  neither nutcut nor netcut-defender to protect and even I tried TuxCut. It's is also not working properly.  Can any one give me the right solution for this?


I have an Ubuntu LTS 16.04.02 with an 4.4.x Kernel from March.  When I try to update the system it claims to be uptodate. This is not true. So why do not get the updates?  root@p1sr1:~# uname -a Linux p1sr1 4.4.0-66-generic #87-Ubuntu SMP Fri Mar 3 15:27:09 UTC 2017 i686 i686 i686 GNU/Linux  root@p1sr1:~# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 16.04.2 LTS Release:    16.04 Codename:   xenial   root@p1sr1:~# sudo apt-get update OK:1 http://archive.canonical.com/ubuntu xenial InRelease OK:2 http://ppa.launchpad.net/x2go/stable/ubuntu xenial InRelease OK:3 http://de.archive.ubuntu.com/ubuntu xenial InRelease Paketlisten werden gelesen... Fertig                   root@p1sr1:~# sudo apt-get upgrade Paketlisten werden gelesen... Fertig Abhängigkeitsbaum wird aufgebaut.        Statusinformationen werden eingelesen.... Fertig Paketaktualisierung (Upgrade) wird berechnet... Fertig 0 aktualisiert, 0 neu installiert, 0 zu entfernen und 0 nicht aktualisiert.**   Edit: after some further information via the comments, it seems that the source.list seems to be not ok on my system.  Does anyone have a default sourcelist for LTS 16.04.2, I like to compare with my system.  Edit II After getting the correct source.lists I could now update to Kernel 4.10 but I am still on LTS 16.04.2 !!  I tried to do an dist-upgrade but this comes back with 0 packages to update... So I am in a much better state now but the initial question:  How can I upgrade from LTS 16.04.2 to LTS 16.04.3 is still on my desk. Any hint is highly well come!

I am looking for the best method to restore /etc/apt/sources.list to default from the command line.  Is there no way to reference the source code of the package which generates this file or something like that? I want a trusted and version-independent way of restoring this file.  Solutions Ruled Out  Before you mark this as a duplicate, note that I have reviewed  already. It is only applicable if you have the Ubuntu GUI available. This question is specific to the command line.  I have also reviewed  where the accepted solution is someone pasted the contents of their sources.list file. This is not an appropriate way to restore the file as the intentions of the person providing the file contents cannot be verified and the file is subject to change with new releases.  I checked out the , but this is also not from Ubuntu so I do not plan to use it.


Alrighty, so I have a program that is supposed to take the first name of the customer, and regardless if the letters in the name are capitalized or lower case, if they are Mike or Diane, it sets the discount to being true and then later on applies the discount. By default discount = false.   Heres getting the name and setting discount to true:  if (firstName == "Mike" || firstName == "Diane")   {      discount = true;   }   And here's later on when I'm trying to apply the discount and lower the cost:  if (discount == true)   {      System.out.println("You are eligible for a $2.00 discount!");      cost = cost - (2.00);   }   However the problem is that when I use Mike or Diane, whether capitalizing or not, it simply does not apply the discount to the price. It compiles and runs, it just doesn't apply the discount.

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?


I have a two files. File 1 looks like this:  a  1   b  6  c  8  The second file is:  a  2 b  4.5 c  3.8  I want to merge file 1 and file 2 in a way that always outputs:  a  1 a  2  b  6 b  4.5 c  8 c 3.8

I have tried to get the 2 files output in a single file.  I have tried below command:  cat file1 file2   but here file2 data is appending to file1.  What I need is file1 1st line followed by file2 first line, and file1 second line followed by file2 second line etc.  Can anybody tell me how to do this in a simple way?


Let's say hypothetically I want to make a videogame based on pathfinder. To what extent can I use their content?  From what I can gather, I can use all mechanics, items, and bestiary, but I can't use any copyrighted content such as artwork, story (such as adventure paths) or proper names? I also assume I can't use the word pathfinder except to say the game is based on its rule set.  Does this sound correct? Am I missing anything?

I am sketching out my 2012 programming project, and Im planning to make a classic fantasy RPG game.  The world design, plots, characters and all that I can make, but being a avid tabletop role-player, I would love to use a stable and tested rpg system like Pathfinder, since its balanced and interesting.  Would there be a problem if I make a game (indie dev, but still planning on selling it) using the pathfinder license ? Do I have to purchase a license? And would I able to say that it's based on the Pathfinder ruleset, or should i keep that under wraps.  All big official D&D games boast with that they are official, so doesn't this mean that unofficial games can exist too ?  It's not because I wan't to jump the lowest fence, and all storylines and the game setting will be by my own hand. But I love the Pathfinder system and actually think it could use some publicity as well.  If not, I guess I could make a Pathfinder-like system, with a few measely differences... But I would rather not, since it would feel a bit of a rip...


In a terminal I copy a line by Ctrl+a and Ctrl+k. I want to copy the text into clipboard when another window become active so that I can use the text another application, like a text editor or a browser.  Is there way to do it?

In  the top answer shows how to copy text that has been previously selected with the mouse on a gnome-terminal, to the clipboard in X11.  My question is: Say I copy a piece of text from the terminal using bash set-mark and copy keyboard shortcuts (i.e. set-mark + M-w). Is it possible to share this clipboard with X11?   EDIT: In the original question, I talked about sharing the clipboard with GNOME, but as Gilles points out below, GNOME doesn't specifically have a clipboard (it's general to X), so I have updated the question.


First of all I'll describe my problem. I'm writing a publication in which I need to introduce three tables that have a lot of data. In order to fit the maximum space allowed, I made the tables smaller but this causes the tables to be very small and makes difficult to read the data. The tables can't overcome the width of the column. Any tip or solution that can help? Thank you in advance.

I have a table that I want to insert on a page, but at least one (perhaps both) of the following conditions are met:   The table is too wide to fit within the text block or page. That is, I'm exceeding some horizontal restriction. The table is too tall to fit within the text block or page. That is, I'm exceeding some vertical restriction.   What are my options to make this table fit? If it doesn't fit, regardless of my attempts, what other options exist?


Which domain would return better results in Google with search phrase "hair salon" if I hypothetically have several domains, same age with identical content, marketing and SEO? hair.salon vs hair.* (.com, .net, .eu)  I'm building a brand, lets call it "hair". I will buy several domains and redirect them to primary domain, but can't decide which domain to keep as primary.  Does domain extension even contribute to SEO in that way or it doesn't matter what domain extension I use and it's all about content, backlinks, marketing?  Thanks

I've noticed .com is the standard top-level domain, but when should I not use .com? What are the most common alternatives? If someone has foo.com registered, should I choose a different domain or register foo.somethingelse?


In my QGIS-version (2.18.12, Windows) when opening the expression string builder or the field calculator there is no inline help for the functions. I actually never managed to activate this. Is there an option that I am missing?

I don´t have in field calculator "selected function help".


Self-irony is very popular in my home country, Denmark, and I find it defined on the Internet as "the ability to laugh at oneself, to take oneself lightly".  I also find it in some dictionaries but apparently not in the most widely used. Does the word (combo) exist or don't native English speakers know how to laugh at themselves?

I don't mean people with low self esteem.  But there are people who feel happy at being able to make other people laugh at their own expense. I remember someone telling me there is a word for them, I can't find it.  Let me explain:  I sometimes, while sitting with a group of people, might just tell them a personal embarrassing story, which might be completely fabricated, to make other people laugh. And when they laugh, I feel happiness.  I'm also self deprecating, but not in a way that I hate myself, rather,  just my work (I'm a screenwriter) and knowing I can do better. I do not self deprecate myself in public (I don't praise myself either).   Edit: Now that its mentioned, I think the word I'm talking about was used to describe a person's sense of humor. Or it could be a word used to describe a psychological trait/disorder.  Edit: I just looked up humor styles on Wikipedia. And after reading it, I guess the word that closely matches what I'm looking for is 'Affiliated Humor' but in a 'Self Defeating' style.


Given an ordered set $X$, say a subset $Y$ of $X$ is convex in $X$ if for each pair of points $a<b$ of $Y$, the entire interval $(a,b)$ of points of $X$ lies in $Y$. An interval is of the form $(a,b),(a,b],[a,b),[a,b]$, and a ray is of the form $(a,+\infty),(-\infty,a),[a,+\infty),(-\infty,a]$. Let $X$ be an ordered set. If $Y$ is a proper subset of $X$ that is convex in $X$, does it follow that $Y$ is an interval or a ray in $X$?  Well, suppose $Y$ has a smallest element $a$ and a largest element $b$. Then $[a,b]\in Y$, and so $Y=[a,b]$ and $Y$ is an interval. What if $Y$ has no smallest element? So for each element $a\in Y$, there exists an element $b\in Y$ such that $b<a$. What then?

This is from Exercise 7 in p. 92 in Munkres's Topology.  Except for the trivial cases such as $Y$ is empty set or singleton, it seems if $Y$ is convex in an simply ordered set $X$ then $Y$ is interval or ray.  But I cannot start my proof because I cannot use $\sup$ or $\max$ functions.  What should I do?


i have enabled the nested virtualization on a GCP VM instance running Ubuntu. it was working perfectly. from last few days this vm was power off and today when powered it on nested virtualization was disabled?  any idea why its disabled now and how i can enable it again?  root@ubuntu:~# grep -cw vmx /proc/cpuinfo 0 root@ubuntu:~# init 0

I am using GCE for nested virtualization. I am aware of the specific CPU architecture to be used for nested-virtualization compatibility.  Everything is going smoothly and I am using this feature without any issues, however, if I apply the recommendation for instance resizing I noticed that this feature 'nesting virt.' is not available.  I know this by running command grep -cw vmx /proc/cpuinfo and lsmod.


I'm trying to check 2 tables (10k plus rows) for inconsistent data. e.g. both table have a "id" and "price" column and I want to know when id are equal are the price also equal. I would like to create a output that tells me exactly which id have different/inconsistent prices.  I have to do this check 3 times where 1a,1b,1c is all on different servers. table1 - table1a table1 - table1b table1 - table1c  Is this more efficiently done with pure SQL or with a programming language + SQL (python with pyodbc or java with jdbc etc). Since I'm new to SQL I don't know how trivial this would be with pure SQL.

I have two databases - Database1 and Database2.  Both databases contain a table that has similar structure, exemplified as follows:   =========================================================================================== | ID | Name | PhoneNoFormat | DialingCountryCode | InternationalDialingCode | InternetTLD | =========================================================================================== |    |      |               |                    |                          |             | ===========================================================================================   However, due to some reason, (a) one of the tables in one of the databases has data that is not exactly the same as (b) that contained in the other table in the another database.  So, how can I compare Database1.Table1 against Database2.Table1?  I tried using the following query, but nothing happened so was wondering if I have to rewrite it:  SELECT MIN(TableName) as TableName,        ID,        Name,        PhoneNoFormat,        DialingCountryCode,        InternationalDialingCode,        InternetTLD  FROM  (    SELECT  'Table A' as TableName,           A.ID,           A.Name,           A.PhoneNoFormat,           A.DialingCountryCode,           A.InternationalDialingCode,           A.InternetTLD    FROM [D:\DATABASE1.MDF].[dbo].[Table1] AS A    UNION ALL    SELECT 'Table B' as TableName,          B.ID, B.Name,          B.PhoneNoFormat,          B.DialingCountryCode,          B.InternationalDialingCode,          B.InternetTLD    FROM [D:\DATABASE2.MDF].[dbo].[Table1] AS B  ) tmp  GROUP BY ID, Name, PhoneNoFormat, DialingCountryCode, InternationalDialingCode, InternetTLD  HAVING COUNT(*) = 1  ORDER BY ID


Suppose that I have files that I'm afraid to even expose to a system that is connected to the Internet. Therefore, I've put them on a separate computer, which does not have Wi-Fi or any other sort of Internet connection. Though, this means that it's still accessible by USB flash drives and it still has Ethernet ports (since that's relevant to my job) which can be used to connect to the Internet. I know  but can I also disable all networks, the creation of new network connections and any sort of access to the functions that might enable people to do so, unless I need them? I don't want to deal with ports every time I need to test code or equipment. I already have my firewall configured and don't want to disrupt that. What I'm essentially looking for, is a way to doubly secure the computer. What if I forget to lock my computer and within the five minutes it takes to go to the lock screen someone accesses it? Even if people can access the computer, I don't want them to be able to send anything out or in during that time, unless they provide my password. P.S. The title is about physical Ethernet ports where you have to jack a cable in, not the ports that are configured by software inside the computer.

I did the following:  ufw default deny outgoing, sudo ufw allow out 80 which I thought would let me use the Internet but didn't can y'all help?  Also are there any other ports used by Ubuntu for which I should allow outgoing traffic for? I hear these 20, 21, 53, 123, 443 are some what do you all think?  Thanks


How frequent do I have to place powered rails to keep climbing at full speed?   Some people say that you only have to use the same amount from powered and non powered, but you can do like 3 powered and 3 unpowered. This is not true, I tried that out. The best way seems to be switching between powered and non-powered (one powered, one non-powered, one powered, ...), which brings a big waste of redstone torches with it. Any other ideas? I didn't test it enough to prove it.  This is NOT the same question as . I ask specifically for full speed and not "minimum of powered rails/maintain reasonable speed".

When going up a slope, how often must you insert a powered rail to keep your cart going? What is the minimum to keep going at all, and what is a good recommendation for maintaining a reasonable speed?


When you put champaign in a glass, or any other CO2 containing liquid, than often there arise bubble mostly from the same spot.  Bow it is said that the cause for that is that bubbles of CO2 'like to gather' at a tiny unevenness (a sharp point or hole) of the glass. But why should CO2 molecules do this?

Glassware with scratched/etched surfaces generate more bubbles (, ). Why these rough surfaces allow easier heterogeneous nucleation?


Many years ago I took a philosophy class that covered Descartes.  The teacher logically explained to us the "I think Therefore I am" over the course of a week.  He also said that it was one of the very few things that you could prove.  He made it seem like there were other things that could also be proven at the most basic of levels, but he never talked about them.  He then went on to some other topic I think it was about Leibnitz and Monads.  My question is, are there other ideas or things that are provable like the "I think therefore I am" and if so, what are they?  I'm also aware from reading Wikipedia that the "I think therefore I am" can be generalized even further.  But are there any fundamental ideas like it that can also be proven?  I don't know if this helps, but apparently this teacher is one of the best in understanding and interpreting the philosophy of Immanuel Kant.  So it's possible that some of those provable ideas he was referring to might be from Kant.  edit: I want a list of proved things in bullet format preferably. From the other similar questions I was able to get: 1.cogito ergo sum 2.axioms of logic  Are there anymore?

I don't understand philosophy very well, and so I am wondering whether you can "prove" anything in philosophy. It always seems you can go a layer down, and find another question, almost endlessly until you get to the question of "why/how/are we here?"  Can you prove, absolutely, and 100% that something is true, in the field of philosophy?


I am new to Lyx and have spent the better part of a week getting things to work correctly. I am stumped how to fix the problem of the bibliography sorting order not working.  I have a LyX file like this:     Mary had a little lamb.   I insert a citation so now I have:     Mary had a little lamb [1].   I then realize that I needed to cite Mary so I insert again:     Mary [2] had a little lamb [1].   No matter what I do in settings etc, I can not get it to print:     Mary [1] had a little lamb [2].   My set up:  LyX version 2.0.4 MiKTex 2.9 I am using Zotero in conjunction with LyX to build BibTeX database. I have tried different styles: unsrt, plain, ieeter  LyXserverPipe: \.\pipe\lyxpipe  I am totally tired of trying to get this up and working. I am sure the effort will be repaid, but what a pain.  Any help is appreciated.

Can thebibliography be sorted by citation order? Or is there a solution with an inlined bibliography that can be sorted?  Not having an additional .bib file would be preferable.  My current bilbiography is inluded in the rest of the article inside a thebibliography block.  \begin{document} \section{Example} The citations in\cite{ne} the bibliography should\cite{flowers} be ordered  according which order they appear in the text.   \begin{thebibliography}{9}  \bibitem{fetebok} \emph{Internal Combustion Engine Fundamentals}  \bibitem{ne} \emph{Förbränningsmotorer}  \bibitem{flowers} \emph{HCCI Research Towards Development for Stationary Power  Applications}  \end{thebibliography}   Should output:  The citations in[1] the bibliography should[2] be ordered  according which order they appear in the text.   Bilbiography [1] Förbränningsmotorer [2] HCCI Research Towards Development for Stationary Power Applications [3] Internal Combustion Engine Fundamentals


The Lagrangian for a particle of mass $m$ in a potential well $V(r)$ is given by $$ L = \frac{1}{2}m(\dot{r}^2 +r^2\dot{\theta}^2) - V(r).  $$  Working though the Euler-Lagrange equation I get  $$\frac{\partial L}{\partial r}=mr\dot{\theta}^2-\frac{\mathrm{d}V(r)}{\mathrm{d}r} $$ $$\frac{\mathrm{d}}{\mathrm{d}t}\frac{\partial L}{\partial \dot{r}} = m\ddot{r} $$  so the equation of motion for the $r$ coordinate is:  $$ m\ddot{r} = mr\dot{\theta}^2-\frac{\mathrm{d}V(r)}{\mathrm{d}r}. $$  Now the above Lagrangian tells me that there is a conserved quantity $ \frac{\partial L}{\partial \theta} = mr^2\dot{\theta} = l$ so I can express the equation of motion as   $$ m\ddot{r} = \frac{l^2}{mr^3}-\frac{\mathrm{d}V(r)}{\mathrm{d}r}.\tag{1} $$  Well if I was to substitute $l$ directly into the Lagrangian before solving for the equations of motion I get  $$ L = \frac{1}{2}m\bigg(\dot{r}^2 + \frac{l^2}{m^2 r^2}\bigg) - V(r). $$  This Lagrangian gives me   $$\frac{\partial L}{\partial r} = -\frac{l^2}{mr^3} - \frac{\mathrm{d}V(r)}{\mathrm{d}r} $$  and the equation of motion  $$ m\ddot{r} = -\frac{l^2}{mr^3}-\frac{\mathrm{d}V(r)}{\mathrm{d}r}. \tag{2}$$  I have a minus sign on the first term on the RHS and I have a contradiction between $(1)$ and $(2)$. What is going on?

A mass of point performs an effectively 1-dimensional motion in the radial coordinate. If we use the conservation of angular momentum, the centrifugal potential should be added to the original one.     The equation of motion can be obtained also from the Lagrangian. if we substitute, however, the conserved angular momentum herein then the centrifugal potential arises with the opposite sign. So if we naively apply the Euler-Lagrange equation then the centrifugal force appears with the wrong sign in the equations of motion.   I don't know how to resolve this "paradox".


We say that a sequence of random scalars $\{z_{n}\}$   converge in probability to a constant $\alpha$   , if for any $\epsilon>0$  ,$$\lim_{n\rightarrow\infty}\mathbb{P}\left(|z_{n}-\alpha|>\epsilon\right)=0$$  I understand the application of this notion to the Weak Law of Large Numbers, where I understand that when the sample size grows, the sampling distribution of the sample mean approaches the population value. However, the sample mean is a statistic. How can I think of a *sequence *of random scalars when it is not a statistic? What does $n$ mean in that case? Does it still mean sample size? What would convergence in probability mean in that setting? What 'distribution' or hypothetical distribution do we have in mind to compare to $\alpha$?

What is the intuitive difference between a random variable converging in probability versus a random variable converging in distribution?  I've read numerous definitions and mathematical equations, but that does not really help. (Please keep in mind, I am undergraduate student studying econometrics.)  How can a random variable converge to a single number, but also converge to a distribution?


root's default PATH is  $ sudo su # echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games   After creating /etc/cron.d/myjob  35 * * * * tim ( date && echo $PATH && date ) > /tmp/cron.log 2>&1   /tmp/cron.log shows the default value of PATH is:  /usr/bin:/bin   Is the default PATH value in a crontab file not the one for the root? Why?  Whose PATH value is it?   WIll the default PATH value be different if I add the job in /etc/crontab or a file under /etc/cronb.d/?  Does it matter which user is specified in the cron job? (such as tim in the above example)  Thanks.

Cron doesn't use the path of the user whose crontab it is and, instead, has its own. It can easily be changed by adding PATH=/foo/bar at the beginning of the crontab, and the classic workaround is to always use absolute paths to commands run by cron, but where is cron's default PATH defined?  I created a crontab with the following contents on my Arch system (cronie 1.5.1-1) and also tested on an Ubuntu 16.04.3 LTS box with the same results:  $ crontab -l * * * * * echo "$PATH" > /home/terdon/fff   That printed:  $ cat fff /usr/bin:/bin   But why? The default system-wide path is set in /etc/profile, but that includes other directories:  $ grep PATH= /etc/profile PATH="/usr/local/sbin:/usr/local/bin:/usr/bin"   There is nothing else relevant in /etc/environment or /etc/profile.d, the other files I thought might possibly be read by cron:  $ grep PATH= /etc/profile.d/* /etc/environment /etc/profile.d/jre.sh:export PATH=${PATH}:/usr/lib/jvm/default/bin /etc/profile.d/mozilla-common.sh:export MOZ_PLUGIN_PATH="/usr/lib/mozilla/plugins" /etc/profile.d/perlbin.sh:[ -d /usr/bin/site_perl ] && PATH=$PATH:/usr/bin/site_perl /etc/profile.d/perlbin.sh:[ -d /usr/lib/perl5/site_perl/bin ] && PATH=$PATH:/usr/lib/perl5/site_perl/bin /etc/profile.d/perlbin.sh:[ -d /usr/bin/vendor_perl ] && PATH=$PATH:/usr/bin/vendor_perl /etc/profile.d/perlbin.sh:[ -d /usr/lib/perl5/vendor_perl/bin ] && PATH=$PATH:/usr/lib/perl5/vendor_perl/bin /etc/profile.d/perlbin.sh:[ -d /usr/bin/core_perl ] && PATH=$PATH:/usr/bin/core_perl   There is also nothing relevant in any of the files in /etc/skel, unsurprisingly, nor is it being set in any /etc/cron* file:  $ grep PATH /etc/cron* /etc/cron*/* grep: /etc/cron.d: Is a directory grep: /etc/cron.daily: Is a directory grep: /etc/cron.hourly: Is a directory grep: /etc/cron.monthly: Is a directory grep: /etc/cron.weekly: Is a directory /etc/cron.d/0hourly:PATH=/sbin:/bin:/usr/sbin:/usr/bin   So, where is cron's default PATH for user crontabs being set? Is it hardcoded in cron itself? Doesn't it read some sort of configuration file for this?


Is there a death of black holes? If yes, what is the average lifetime of a black hole and what happens when a black hole dies?

Does it just vanish into space leaving nothing behind or does it expel some material?    Also, talking more about black holes, as far as I understand the term "temperature", it is defined by the amount of kinetic energy of the particles of a body and from what I have read, there are no particles inside a black hole, I know that you can find the temperature of a black hole by analyzing its Hawking radiation but I cant really understand how the term "temperature" can be applied to a black hole. Does it mean that whatever is that it is inside a black hole has kinetic energy? Have physicist already experienced the death of any regular black hole (by regular I mean space-sized black holes not micro ones created in labs)? Also, where is the Hawking radiation form? Because if it is released by the black hole I bet it must have formed outside the event horizon, but how exactly?


I've written a PHP code I would like to sell. I want to prevent other PHP programmers from buying the code and than reselling it as their own. (it happens) I might even let others download the code for free, but still don't want those others to upload it to their sites and presenting it as theirs.  I was wondering if there is a way to hide the code from someone who gets a hold of it by somehow converting it to binary or byte code so that whoever downloads it from my site won't able to view the actual code or change it. I mean without requiring the one running the PHP code to install on it's server.  I've seen threads about this from 2011 and 2014 (that didn't have solutions without bugs and do not support PHP7) and wondered if there is anything new in 2017...

First of all, I'm not looking for miracle... I know how PHP works and that there's not really way to hide my code from the clients without using encryption. But that comes with the cost of an extension to be installed on the running server.  I'm looking for something different though... I'm not looking to encrypt my code or even obfuscate it. There are many PHP scripts without encrypted/obfuscated code but they are commercial applications. For instance, vBulletin and/or IP.Board forum applications.  I just want to know what approach do these guys use for their applications...  I'm also open to any other suggestions.  Please note that I'm a single person and not working for a company. My product is also very specific, it won't sell that much. I just want you guys to know that I can't afford to consult a legal professional either to sue someone or prepare a commercial license. I'm just looking for a simple way to protect my simple product, if it's indeed possible, somehow...


First every time it asks me for a password in a terminal all the keys on my keyboard stop working completely fine all the time until it asks for the terminal password so I cant do anything  Second. When it first booted up I was so happy my DVD drive which stopped working in Windows was suddenly cured and burned a few DVDs but now it doesn’t even show up anywhere   I'm completely new to this so type slowly

When I'm about to install a program in the terminal it wants the password:  [sudo] password for xxx:   But when I start to type my password nothing happens. What should I do?


I have a key value storage which I have data stored. When I retrieve the value it is a JSON with a property "compressed_value", this value is a string and I don't know how to decompress or deserialize it. I tried a lot of approaches, one of them try to cast the string to a byte[] using .getBytes() with different charsets, and using GZIPInputStream but I always get the error "java.util.zip.ZipException: Not in GZIP format". The value es something like: "H4sIAAAAAAAA/wtOzC3ISVUoSa0oUSjJSCxRyFRITswrUUhJLU4tykzMyaxK1VFISczLVQQAkIb0eioAAAA=". When I paste it in a web like  one, it deserialize the value without problem. Example code public class Main {     public static void main(String[] args) throws IOException {     String compressedValue = "H4sIAAAAAAAA/wtOzC3ISVUoSa0oUSjJSCxRyFRITswrUUhJLU4tykzMyaxK1VFISczLVQQAkIb0eioAAAA=";          try {             final int BUFFER_SIZE = 32;             ByteArrayInputStream is = new ByteArrayInputStream(compressedValue.getBytes());             GZIPInputStream gis = new GZIPInputStream(is);             byte[] data = new byte[BUFFER_SIZE];             int bytesRead;             ByteArrayOutputStream baos = new ByteArrayOutputStream();             while ((bytesRead = gis.read(data)) != -1) {                 baos.write(data, 0, bytesRead);             }             gis.close();             is.close();             System.out.println(baos.toString("UTF-8"));         } catch (IOException ex) {             ex.printStackTrace();         }     } }

I have an image that is Base64 encoded. What is the best way to decode that in Java? Hopefully using only the libraries included with Sun Java 6.


In below code variable even if a,c and d stores the same value  (a==c) - is false while (a==d) is true String a="test", String b=a.toUpperCase(); String c=b.toLowerCase(); String d="test"; System.out.println(a==c); // o/p - false System.out.println(a==d);  // True

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?


I can see that Ubuntu 16.04 (Xenial Xerus) did not get Java 11 packages through official updates. However Ubunu 18.04 LTS (Bionic Beaver) got Java 11  even though 18.04 release date is earlier than Java 11 release date?  I was wondering if Ubunu 18.04 LTS (Bionic Beaver) will get Java 17? or if it does not exist in release, it is not included ever?  Is there an official document describing this for Java LTS releases? I found the SRU but it seems to have somewhat conflicting information.  For example the  (SRU) clearly explains in 2.2. Other safe cases     In the following cases a stable release update is also applicable as   they have a low potential for regressing existing installations but a   high potential for improving the user experience, particularly for   Long Term Support releases.   in the same heading, it also says:     For Long Term Support releases we sometimes want to introduce new   features. They must not change the behaviour on existing installations   (e. g. entirely new packages are usually fine).   Now Java 17 would be a discrete update, as it would not effect existing Java 8/11 installations. Because for example providing openjdk-11-jdk package does not do any changes to systems where openjdk-8-jdk package is installed. Therefore, logically thinking the Ubuntu documentation says that newer LTS Java updates should gladly be included in 18.04 when Java 17 is available.   However this was not the case for 16.04 so why isn't Java 11 included with 16.04? I don't quite understand this.  In addition, for example 14.04 was released with . This is much more disruptive update compared to adding a new Java XX version package to repository.  Thanks!

Why are packages in the official Ubuntu repositories older than the latest (upstream) versions from Debian Sid, PPAs, the authors, etc.?


I'm trying to generate a apex class from WSDL actually i am importing some Web Services which are in the RPC/Encoded style.  i am having this issue while generate apex code from WSDL  Error : Unsupported WSDL style 'rpc'. Only supports Dcoument/literal/wrapped services.  Is it possible to develop Apex Code by hand which will talk with these Web Services? Some how i really want to create this class, if you have any suggestion would be helpful for me, thanks in Advance

We have an application which we need to integrate with salesforce.   Unfortunately this legacy application supports RPC SOAP calls only, we cannot use out of the box wsdl2apex to build the integration on it. Doing so gives the error:     Unsupported WSDL style 'rpc'. Only supports Document/literal/wrapped services.   We are considering an inbetween Heroku layer where we can build a custom java app to build the integration between salesforce and other application. Is there a better way to do this or how do you guys currently do an SOAP RPC call using apex? Is there any tool which can do SOAP RPC integration?


I am trying to use a JS variable in CSS.   In JavaScript it's:  var bodybg = "#fff"   And in CSS:  body {   background-color: bodybg; }   How do I achieve that?

It's easy to set inline CSS values with javascript. If I want to change the width and I have html like this:

   All I need to do is:  document.getElementById('id').style.width = value;   It will change the inline stylesheet values. Normally this isn't a problem, because the inline style overrides the stylesheet. Example:

   Using this Javascript:  document.getElementById('tId').style.width = "30%";   I get the following:

   This is a problem, because not only do I not want to change inline values, If I look for the width before I set it, when I have:

   The value returned is Null, so if I have Javascript that needs to know the width of something to do some logic (I increase the width by 1%, not to a specific value), getting back Null when I expect the string "50%" doesn't really work.  So my question: I have values in a CSS style that are not located inline, how can I get these values? How can I modify the style instead of the inline values, given an id?


Example of file with duplicate lines:   # more  file.csv   spark2-env,spark_thrift_cmd_opts,--driver-memory 15g --executor-cores 7  spark2-thrift-sparkconf,spark.memory.offHeap.enabled,true  mapred-site,yarn.app.mapreduce.am.command-opts,-Xmx5324m -Dhdp.version=${hdp.version}  spark2-env,spark_thrift_cmd_opts,--driver-memory 15g --executor-cores 7   We created the following awk in order to delete the lines with duplicate strings only in fields 1 and 2, but awk from some unclear reason also deletes  the line where field 3 is duplicate.  What is wrong with my awk syntax?   # awk -F, 'NR==FNR{a[$1,$2]++; next} a[$1,$2]==1'  blueprint_param_file.csv  blueprint_param_file.csv   spark2-thrift-sparkconf,spark.memory.offHeap.enabled,true  mapred-site,yarn.app.mapreduce.am.command-opts,-Xmx5324m -Dhdp.version=\${hdp.version}   Expected output:  spark2-env,spark_thrift_cmd_opts,--driver-memory 15g --executor-cores 7 spark2-thrift-sparkconf,spark.memory.offHeap.enabled,true mapred-site,yarn.app.mapreduce.am.command-opts,-Xmx5324m -

by the following command we can print the duplicate lines from file  uniq -d string file.txt   but how we can do it on csv file ?  we need to print the duplicate lines only on fields 1,2 from csv file - not include field 3  FS - ","  for example:   spark2-thrift-sparkconf,spark.history.fs.logDirectory,{{spark_history_dir}}  spark2-thrift-sparkconf,spark.history.fs.logDirectory,true  spark2-thrift-sparkconf,spark.history.Log.logDirectory,true  spark2-thrift-sparkconf,spark.history.DF.logDirectory,true   expected results:   spark2-thrift-sparkconf,spark.history.fs.logDirectory,{{spark_history_dir}}  spark2-thrift-sparkconf,spark.history.fs.logDirectory,true   second:  how exclude the duplicate lines from the csv file ( I mean to delete only the duplicate lines on fields 1,2   expected output:   spark2-thrift-sparkconf,spark.history.Log.logDirectory,true  spark2-thrift-sparkconf,spark.history.DF.logDirectory,true


I write tic tac toe and i have small problem.  When checking the fields, console write error:  Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at pl.knugi.Main.sprawdzKombinacje(Main.java:164) at pl.knugi.Main.actionPerformed(Main.java:179)   This code:      public boolean sprawdzKombinacje(String p){     String[] spr = new String[3];     for(JButton[] c : check){         int a = 0;         for(JButton b : c){             spr[a]=b.getText();             a++;         }         if(spr[0].equals(p)&&spr[1].equals(p)&&spr[2].equals(p)){             return true;         }     }     return false; }   Variables:  JButton[] check1 = {button1, button2, button3}; JButton[] check2 = {button4, button5, button6}; JButton[] check3 = {button7, button8, button9}; JButton[] check4 = {button1, button4, button7}; JButton[] check5 = {button2, button5, button8}; JButton[] check6 = {button3, button6, button9}; JButton[] check7 = {button1, button5, button9}; JButton[] check8 = {button3, button5, button7}; JButton[][] check = {check1, check2, check3, check4, check5, check6, check7, check8};   What am i doing wrong?  Problem is b.getText(), because this is AbstractButton. Then how I getted text from my button ?

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?


I noticed on my phone bill that I have a lot of sent SMS messages which I'm not aware of and can't find in the sms app.  Is there a way to find out which app is sending these messages? And how to view the details of these messages on my android phone (I'm using Galaxy S7 Edge).

I normally have "Block Premium Messaging" set up on the phones in my family. This is a verizon content block the prevents you (or family members) from sending messages to premium services that charge.  Recently, I had to replace a phone that broke and when the new phone was activated the blocks I had set up were cleared. On my bill was a $9.99 charge for a text to one of these premium services.   I know nobody sent the SMS to the service to sign up for this. I suspect some application on the phone sent the SMS message. Is there a way I can find out which app on my phone is sending SMS messages to premium services? Can I view all the apps that have permission to send SMS messages?  -- update -- well, I ran RL Permissions and no downloaded apps have the Send SMS permissions. I must have already deleted the offending app or something else is going on.


I have no idea of proving $H\otimes l^{2}(\Gamma)\cong\bigoplus\limits_{g\in \Gamma}H$,where H is a hilbert space,$\Gamma$ is a discrete group, $l^{2}(\Gamma)$ is the set of all complex valued square summable fuctions on $\Gamma$.

Let $H,~K$ be the Hilbert space. if $\{v_{j}\}_{j\in J}\subset H$ and $\{w_{i}\}_{i\in I}\subset K$ are the orthonormal bases, then how to construct the isomorphic mapping: $H\otimes K \rightarrow \bigoplus\limits_{i\in I}H$. Here, the $H \otimes K$ is the tensor product of two Hilbert space.


EDIT: I found the solution for the problem. The float package is necessary to use figures in a multicol environment.  When trying to insert an image into a document, I am unable to use a figure. This following code describes what I am trying to do, but it is not functional.  \documentclass[twoside]{article} \usepackage{graphicx}  \begin{multicols}{2}  \begin{figure}[h]     \includegraphics{image} \end{figure}   On the other hand, not declaring the image as a figure works. The following code is functional, but since the image is not a figure, I cannot properly caption and whatnot:   \documentclass[twoside]{article} \usepackage{graphicx}  \begin{multicols}{2}  \includegraphics{image}   How do I properly insert the image as a graphic, so that I can work with it more?

I am having the following problem with adding a figure inside the multicol environment:  \documentclass[10pt, twoside]{book} \usepackage{graphicx} \usepackage{subfig}  \begin{document}   \begin{multicols}{2}  a test file for picture inclusion along with the captions and labeling \begin{figure}  \centering  \includegraphics[width=5cma]{Cauchy_sequence_illustration-png}\\  \caption{Lets see}\label{pinki} \end{figure} \end{multicols}  \begin{figure}  \centering   \includegraphics[width=5cm]{Cauchy_sequence_illustration-png}\\  \caption{Lets see}\label{pinki} \end{figure}    \end{document}    After this while I am pressing Ctrl + Shift + X (usually I compile like this in DVI format and then clicking "dvi--->pdf" I convert it into PDF document.) the picture in multicol environment is not shown in YAP Viewer but the second one (which is outside of multicol environment) is shown along with the caption.  Kindly help me how to handle this problem. Please note that I am using the figure in .ps format. And I am not allowed to use any other format according to the instruction.


I am having Dell studio 1458 with Intel core i5 processor @ 2.27 Ghz and 4GB ram with 320 GB Hard disk space.Weather it is enough for latest ubuntu.

I'm thinking about installing Ubuntu Desktop, but I don't know what flavor is the best for my system. What are the minimum and recommended hardware requirements? What kind of CPU? How much memory? Should I have Hardware Acceleration? What flavor should I use?  This is an attempt of a canonical answer. My answers have the "official  requirements", the recommended are a mix of official sources and opinion based (along with the answer it's told the source). You can comment or edit if you feel that the information is obsolete or incomplete. It is a good rule of thumb that any system capable of running Windows Vista, 7, 8, x86 (Intel) OS X will almost always be a lot faster with any Ubuntu flavor even if they are lower-spec than described below.


I saw the main Stack Exchange site  has tiles for all of their sites. Is the size of the tiles/speechbubbles representative of the (logarithmic?) quantity of questions for each site or the current activity for each site?  Regardless, very cool feature.

I noticed that  has been changed, and by default sites are shown by balloons.  What is not clear to me is why some sites are shown with a bigger balloon than other sites. For example, WordPress Answers has less questions, answers and users than Programmers, but its balloon is bigger. What are the criteria used to show the sites on that page?


When installing updates, I get this error:  $ sudo apt-get update  Hit:11 http://ppa.launchpad.net/lutris-team/lutris/ubuntu cosmic InRelease Hit:13 http://ppa.launchpad.net/system76/pop/ubuntu cosmic InRelease            Reading package lists... Done  N: Skipping acquire of configured file 'main/binary-1386/Packages' as repository 'http://apt.pop-os.org/proprietary cosmic InRelease' doesn't support architecture '1386' N: Skipping acquire of configured file 'main/binary-1386/Packages' as repository 'http://us.archive.ubuntu.com/ubuntu cosmic InRelease' doesn't support architecture '1386' N: Skipping acquire of configured file 'restricted/binary-1386/Packages' as repository 'http://us.archive.ubuntu.com/ubuntu cosmic InRelease' doesn't support architecture '1386' N: Skipping acquire of configured file 'universe/binary-1386/Packages' as repository 'http://us.archive.ubuntu.com/ubuntu cosmic InRelease' doesn't support architecture '1386' N: Skipping acquire of configured file 'multiverse/binary-1386/Packages' as repository 'http://us.archive.ubuntu.com/ubuntu cosmic InRelease' doesn't support architecture '1386' repository 'http://ppa.launchpad.net/system76/pop/ubuntu cosmic InRelease' doesn't support architecture '1386'   That happens to me errors from repository's of ubuntu, system 76 winehq also for updates.   $ dpkg --print-foreign-architectures i386 1386   I try to remove 1386 (I must have installed while updating and installing updates for ubuntu, wine or lutris)  $ dpkg --remove-architecture 1386 dpkg: error: unable to create new file '/var/lib/dpkg/arch-new': Permission denied   Does anyone have idea of how to remove or 'instill privileged' for access to read & write to system architecture.

Getting below error message while issuing :  sudo apt-get update  Get:1 http://us.archive.ubuntu.com/ubuntu xenial InRelease [95.8 kB] Ign:2 http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.2 InRelease                                                                                Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease                                                                                Hit:4 http://ppa.launchpad.net/canonical-x/vulkan/ubuntu xenial InRelease                                                                                Hit:5 http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.2 Release                                                                             Hit:6 http://us.archive.ubuntu.com/ubuntu xenial-security InRelease                                                   Ign:7 http://dl.google.com/linux/talkplugin/deb stable InRelease                                                      Hit:8 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease                                                    Ign:9 http://linux.dropbox.com/ubuntu wily InRelease                                            Hit:10 http://ppa.launchpad.net/numix/ppa/ubuntu xenial InRelease                               Get:12 http://dl.google.com/linux/chrome/deb stable Release [782 B]       Hit:13 http://dl.google.com/linux/talkplugin/deb stable Release                   Ign:14 https://apt.dockerproject.org/repo ubuntu-wily InRelease           Hit:15 https://apt.dockerproject.org/repo ubuntu-wily Release             Get:16 http://dl.google.com/linux/chrome/deb stable Release.gpg [181 B]   Hit:17 http://linux.dropbox.com/ubuntu wily Release                                   Get:20 http://dl.google.com/linux/chrome/deb stable/main amd64 Packages [1,191 B] Fetched 98.0 kB in 0s (118 kB/s)                                  Reading package lists... Done N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://dl.google.com/linux/chrome/deb stable InRelease' doesn't support architecture 'i386'   This cuts across various releases of ubuntu


which one is correct- Let's go on a bus/go in a bus/ go by a bus ? I am confused with these three options.

Examples:   In a car, van, etc. On a bus, boat, motorcycle, etc.   How can one decide which preposition to use? Is memorization the only way or is there a better way?  Note: People generally explain this by either distinguishing between open and closed vehicles or between large and small vehicles. However, the examples I've given defeat both explanations.


My internal storage is about 50MB and my SD Card is about 300 MB. When I want to download an app that only need 20 something MB, it says insufficient storage. Even though I delet most of my apps and make my internal storage to about 100MB, it still says insufficient storage when I want to download an app that need 20MB. Please help me to solve this problem as soon as possible.

Every time I go to install a new app, I get the message "Insufficient storage", and an unable to install anything!  I am using Samsung GT19060 my internal memory is 8GB. I have not downloaded anything but anytime I try to download something it will tell me low memory space.


I know for a fact that the information is right, but when I try to log in, it says: InvalidCredentialsException: Invalid credentials. Invalid username or password. The launcher's version is 1.6.89-j (the java version, the program executes a javabinary). Also, if it helps, I am on Debian 8, 32-bit (I know I can't use the newer versions, I only want to run the older ones that support the 32-bit LWJGL).

We just got a new laptop (ASUS) though we did have a mac.  We are trying to log onto Mojang to download Minecraft and it keeps saying, "The username and password are not recognized."   We have done all the usual procedures; we have reset the password, we are using the email, not the username to sign in, and it looks like the minecraft login servers are working etc. etc.  We quit Minecraft on the old computer and shut off that computer thinking that was the issue.   Still, we can't get onto Mojang.  We are accessing mincraft through firefox and trying to download it to the new computer but we can't get into the account to do that!  What in the world could be the issue?


Where can I get a list of all Plain TeX macros. In the TeXbook, it is said that Plain TeX adds about 600 macros (to the ~300 TeX primitives). Where are they listed (with their documentation)?

Everywhere in the TeX community, I see suggestions like \parskip, \obeylines, \parindent, etc. I'd be surprised not to find them even in the most basic LaTeX packages. So I figured they must be deeper down in the TeX core as primitives. Knowing how they work would be very useful.  Googling for tex primitives takes me to . Is there a printable PDF version of such a reference?


I suppose my function isn't correctly defined since when I replace table html code, table rows don't trigger anymore the function they are bound with.  Here is my HTML table:
           bla bla	           30,00
   And my javascript code:  var formAjaxSubmit = function(form, modal, obj_to_replace = false) {     $(form).submit(function (e) {         e.preventDefault();         $.ajax({             type: $(this).attr('method'),             url: $(this).attr('action'),             data: $(this).serialize(),             success: function (xhr, ajaxOptions, thrownError) {                 if ( $(xhr).find('.has-error').length > 0 ) {                     $(modal).find('.modal-body').html(xhr);                     formAjaxSubmit(form, modal);                 } else {                     $(modal).modal('toggle');                      if (obj_to_replace !== false) {                         $(modal).modal('toggle');                         obj_to_replace.parentNode.innerHTML = xhr;                     }                 }},             error: function (xhr, ajaxOptions, thrownError) {                 // handle response errors here             }         });     }); };  $('.open-row-modal').click(function() {     var url = $(this)[0].attributes.href;     var parent_card = findAncestor($(this)[0], 'card-default');     let load = $('#form-modal-body').load(url.value, function () {         $('#form-modal').modal('toggle');         formAjaxSubmit('#form-modal-body form', '#form-modal', parent_card);     }); });  function findAncestor (el, cls) {     while ((el = el.parentElement) && !el.classList.contains(cls));     return el; }   When the table is replaced, the click function is not triggered anymore.

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.


I was looking in /usr/bin tonight and saw this:    The symbolic link in cyan / red is a curiosity:  lrwxrwxrwx  1 root root          25 Jul 19 04:48 ubuntu-core-launcher -> ../lib/snapd/snap-confine*   As I don't use snapd yet (Ubuntu 16.04 / Unity Interface) I'm not really concerned but I'm curious if anyone else has encountered this strange coloured link and what it means with all the dangerous looking red?

What do the different colours in Ubuntu's ls command mean? For example, when I type the ls command in one of my folders, I get one of the files in light green, the other (which is a folder) in blue with green highlighting.   What do those colours mean, and there is any manual about all the colours?


By placing 27 squares with an area of 1 meter inside of a circle with the radius of 2 meters, prove that exist such a point that belongs to 3 different squares. (each one of the squares $\subseteq$ in the circle completely)   now I know that the combined area of the squares is 27 and 2 combined area of the circles is only $8\pi<27$ so the point that I need to prove that exist is indeed exist but I can't figure out how to do it formally with the Pigeonhole principle.  thanks in advance and sorry about the english  edited: I need a solution that involves the Pigeonhole principle

By placing 27 squares with side $1$ in a circle with radius $2$, such that each square is entirely inside the circle, prove that there exists a point that 3 squares share (inside of their area).    I thought about dividing the circle into 9 equal areas and using the pigeonhole principle, but got stuck there. Any hint will help.


I started my Ubuntu 18.04 this morning and it is booting for over 20 minutes now. I already figured out, that by pressing escape, I can get into a mode where I am able to see what is going on. It says: "failed to mount media/m-proc" see systemctl status "media-m\\x2dproc.mount" for details.   But I don't know how to do that. How can I access a terminal or something if it is still booting? Sorry, for this very basic question!

How do I access the recovery mode in Ubuntu 18.04? I don't see any form of grub bootloader when the system boots - it just goes straight into the OS.


I have a div tag which contains text, and I want to align the contents of this div vertically center.  Here is my div style:        div {      height: 200px;      line-height: 200px;      text-align: center;      border: 2px dashed #f69c55;    }    span {      display: inline-block;      vertical-align: middle;      line-height: normal;    }   Here is my html
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Haec et tu ita posuisti, et verba vestra sunt. Non enim iam stirpis bonum quaeret, sed animalis. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Haec et tu ita posuisti, et verba vestra sunt. Non enim iam stirpis bonum quaeret, sed animalis. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Haec et tu ita posuisti, et verba vestra sunt. Non enim iam stirpis bonum quaeret, sed animalis. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Haec et tu ita posuisti, et verba vestra sunt. Non enim iam stirpis bonum quaeret, sed animalis.
   I wanna text like in image below:-   i.stack.imgur.com/a5wQe.png

I have a div with two images and an h1. All of them need to be vertically aligned within the div, next to each other. One of the images needs to be absolute positioned within the div. What is the CSS needed for this to work on all common browsers?

testing...


I have been studying Cauchy criterion for sequences, and have come across a rather simple proof for the harmonic series, and why it diverges.   More so, we have the following:  $$\sum_{n=1}^{\infty}\frac 1n=\infty\Rightarrow divergent$$  Here is my simple proof:  Consider the sequence $\left\{a_n\right\}_{n=1}^{\infty}$ such that $a_n=\frac 1n$, then $\forall \epsilon>0,\exists \ N \in\mathbb{R}$ for $m,n\in \mathbb{N}$, such that,  $$m,n>N\Rightarrow|a_m-a_n|<\epsilon$$  Pick $m=2n$, then we have the following:  $$|a_{2n}-a_n|=\sum_{k=n+1}^{2n}\frac {1}{k}\geq \sum_{k=n+1}^{2n} \frac {1}{2n}=\frac 12$$  So pick $\epsilon=\frac 12\Rightarrow  \left\{a_n\right\}_{n=1}^{\infty}$ is not Cauchy and thus divergent.  My question is, are there any other slick and easy proofs for the above claim, and if so, what are they? This series at first surprised me, as it initially doesn't seem divergent.  Thanks in advance!

Can someone give a simple explanation as to why the       $$\sum_{n=1}^\infty\frac1n=\frac 1 1 + \frac 12 + \frac 13 + \cdots $$   doesn't converge, on the other hand it grows very slowly?   I'd prefer an easily comprehensible explanation rather than a rigorous proof regularly found in undergraduate textbooks.


I have a c# Windows Service that is required to call an exe periodically.  That exe need to interact with desktop. When I installed the service, I clicked "Allow service to interact with desktop" option.     Service Starts fine but it is not running the exe as expected.           var myProcess = new Process         {             StartInfo = new ProcessStartInfo(@"C:\windows\TestApplication\TestApplication.exe"),             //StartInfo = new ProcessStartInfo(@"C:\temp\Projects\TestConsoleApp\TestConsoleApp\bin\Debug\TestConsoleApp.exe"),         };         myProcess.StartInfo.Domain = "MyDomain";         myProcess.StartInfo.UserName = "Testuser";         myProcess.StartInfo.Password = pwd;         myProcess.StartInfo.CreateNoWindow = true;         myProcess.StartInfo.UseShellExecute = false;         myProcess.StartInfo.CreateNoWindow = true;         myProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;         myProcess.Start();         myProcess.WaitForExit();   Any ideas as to what could be the issue? Is Local System Account does not have access to the System ? How do I find the Local System Account?   Any pointers?

I'd like to periodically run an arbitrary .NET exe under a specified user account from a Windows Service.   So far I've got my windows service running with logic to decide what the target process is, and when to run it. The target process is started in the following manner:   The Windows Service is started using "administrator" credentials. When the time comes, an intermediate .NET process is executed with arguments detailing which process should be started (filename, username, domain, password). This process creates a new System.Diagnostics.Process, associates a ProcessStartInfo object filled with the arguments passed to it, and then calls Start() on the process object.   The first time this happens, the target process executes fine and then closes normally. Every subsequent time however, as soon as the target process is started it throws the error "Application failed to initalize properly (0xc0000142)". Restarting the Windows Service will allow the process to run successfully once again (for the first execution).  Naturally, the goal is to have target process execute successfully every time.  Regarding step 2 above: To run a process as a different user .NET calls the win32 function CreateProcessWithLogonW. This function requires a window handle to log the specified user in. Since the Windows Service isn't running in Interactive Mode it has no window handle. This intermediate process solves the issue, as it has a window handle which can be passed to the target process.  Please, no suggestions of using psexec or the windows task planner. I've accepted my lot in life, and that includes solving the problem in the manner stated above.


we are given $z^n=(z+1)^n=1$, $z$ complex number. we want to prove that $n$ is divisible by $6$. I showed that $|z|=|z+1|=1$. Hence $z$ is on the intersection of two unit circles, one centered at $(0,0)$ and the other one centered at $(-1,0)$. Then $z$ can take two values $z=\operatorname{cis}(2 \pi /3)$ or $z=\operatorname{cis}(4 \pi/3)$. Then from $z^n=1=\operatorname{cis}(2 \pi k)$, $k$ integer I showed that $n$ should be divisible by $3$. I am left to show that $n$ should be divisible by $2$. I think if I figure out a way to show that $\operatorname{arg}(z+1)=\pi/3$ or $-\pi/3$ then I would be done, by using $(z+1)^n=\operatorname{cis}(2\pi k)$. but how can I do this? Any ideas are welcome! Thanks in advance!

Let $z$ be a complex number, and let $n$ be a positive integer such that $z^n = (z + 1)^n = 1$. Prove that $n$ is divisible by 6.  For this problem I am stumped...how should I begin? Also there's a hint for it:  From $z^n = 1$, prove that $|z| = 1$. What does the equation $(z + 1)^n = 1$ tell you? What do the resulting equations tell you about $z$?  Could someone give me a hint on where to begin? thanks in advance


Note: I couldn't find a straight-forward answer in any of the duplicates flagged for this question. The problem is the "right answer" seems to depend very heavily on which release you are running and whether you have a desktop or server profile. I have a bit of both because I installed lubuntu-core to provide some basic remote X functionality and it seems NetworkManager was installed as well but we prefer to edit our network config by hand not use the GUI tools.  Situation is I have a remote Ubuntu 14.04 server I need to reconfigure networking on. I need to safely add a bridged interface eth1 to the remote system without breaking remote connectivity. I have a new /etc/network/interfaces file I want to load but because I don't have an equivalent machine to test it on or physical access to the server I have some questions about my new configuration:   Is the gateway configuration and metric in the file below valid for what I'm trying to do and, Will network manager override or interfere with what I'm doing here? Currently when I ifup eth1 network manager just brings it down automatically. I'm afraid to disable NM in case it kills the remote connection, and If I reboot the system with the updated file and my current configuration should it be able to receive a remote SSH connection when it comes back up?   The server has NetworkManager currently running however I don't need it. I only care that the configuration in /etc/network/interfaces is used and that the machine remains accessible for remote SSH login at all stages of reconfiguration (ie, I do not want to get locked out by a misconfiguration or by taking both interfaces down without a script or reboot automatically and correctly bring them back on).  eth0 is the default interface for host traffic. eth1 is going to be a bridge for a KVM virtual machine with it's own external IP address. Both interfaces connect to the same physical switch and share the X.X.X.0/24 subnet. My understanding is I need a bridge for this to work BUT I also need to be careful about my gateways and metrics because I have 2 interfaces on the same network.  The host currently has the following NetworkManager status:  # nmcli d status DEVICE     TYPE              STATE eth1       802-3-ethernet    unavailable eth0       802-3-ethernet    unmanaged   And configuration in NetworkManager.conf:  [ifupdown] managed=false   I've created the new config below:  # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback  # The primary network interface auto eth0 iface eth0 inet static         address X.X.X.4         netmask 255.255.255.0         network X.X.X.0         broadcast X.X.X.255         gateway X.X.X.1         # dns-* options are implemented by the resolvconf package, if installed         dns-nameservers X.X.X.2         dns-search example.com         # Interfaces with lower values get used first         metric 10  ### NEW BRIDGED INTERFACE ON ETH1 ### auto eth1 iface eth1 inet static         address X.X.X.7         netmask 255.255.255.0         network X.X.X.0         broadcast X.X.X.255         # do I need gateway here or will it conflict with eth0 ?         # gateway X.X.X.1         metric 20  auto br0 iface br0 inet static         address X.X.X.200         netmask 255.255.255.0         network X.X.X.0         broadcast X.X.X.255         gateway X.X.X.1         bridge_ports eth1         bridge_stp off         bridge_maxwait 5         # dns-* options are implemented by the resolvconf package, if installed         dns-nameservers X.X.X.2         dns-search example.com         metric 30   As I said though, with this new config just added to the server an ifup eth1 only works until NM decides to remove it. That's making testing anything problematic but I'm worried simply disabling NM could be much worse.

I have seen a lot of questions related to Bridge and network manager. however none of them seem to apply to what i seen AND want.  I setup my bridge in /etc/network/interfaces. This works perfectly; it uses a nice static ip etc.  However once I rebooted, the network manager says it is unmanaged (as in it can't manage the bridge/connections).  Now this would normally be fine, but I kind of need/want something else on this computer as well.  The first question is:  Is it possible using openVPN (or any other vpn) connection on a bridged interface?  If so, how do I get Network Manager to manage the bridged interface? (as at this point VPN is set up there, but doesn't work/connect because it's unmanaged.)


Last summer I did an internship in an industry for 9 weeks. It was a great experience and my supervisor was a very formal and professional lady. On my last day, she asked about my graduation date and I told her it’s just 6 months away as it was my last semester. She responded: "Send me your CV when you graduate.”  I sent her a mail today and got this reply.   “Good to see your email and glad to know that you have achieved an important milestone.  Congratulations on your graduation. Your CV has been received and shall be forwarded to HR.  All the best for your future endeavors.”  What should be my response now? I don’t wanna sound immature  or unprofessional.  I was thinking about a thank you or something but I don’t know  if that would be appropriate.

I did a summer internship in an industry for 9 week. It was a great experience and my supervisor was a very formal and professional lady. She rarely smiled but appreciated my work every now and then. On my last day, she asked about my graduation date and I told her it’s just 6 months away as it was my last semester.  She responded: "Send me your CV when you graduate.”  Now I want to write to her. How do I begin with that? It’s been 6 months and there’s no particular opening in that department. Should I send my CV in the first mail itself? If so should I also include a cover letter? What's the best way to introduce myself?


I have 2 classes: class A and class B, both classes are packageless (in default package). I want to import and use A's static variable into B. How do I do that so that it compiles?  The following is not compiling:  A.java  public class A {     public static int x = 10; }   B.java  import static A.x;  public class B {     public static void main(String[] args) {         System.out.println(x);     } }   Compiler output: B.java:1: error: static import only from classes and interfaces

I'm working now together with others in a grails project. I have to write some Java-classes. But I need access to an searchable object created with groovy. It seems, that this object has to be placed in the default-package.   My question is: Is there a way to access this object in the default-package from a Java-class in a named package?


How can I resequence the value start of a Sequence in PostgreSQL?

I ran into the problem that my primary key sequence is not in sync with my table rows.   That is, when I insert a new row I get a duplicate key error because the sequence implied in the serial datatype returns a number that already exists.  It seems to be caused by import/restores not maintaining the sequence properly.


We know from Euler's formula that for $\theta \in \mathbb{R}$  we have $e^{i\theta} = \cos(\theta) + i \sin (\theta)$ which is a single complex number.  However, If I apply the definition of complex power $z^\alpha = e^{\alpha \log z}$ I get the following for $z=e$ and $\alpha = i \theta$:  $e^{i \theta} = e^{i \theta \log e} = e^{i \theta (Log|e| + i\arg e)} = e^{i\theta (1+2k\pi i)} = e^{-2k\pi \theta} \cdot e^{i\theta}$ with $k \in \mathbb{Z}$  This means that $(1-  e^{-2k\pi \theta}) \cdot e^{i \theta} = 0$.  We know that $e^{i \theta}$ cannot be zero. So it must be that $1-  e^{-2k\pi \theta} =0$ for all real $\theta$. This means that $k=0$. So $e^{i\theta} = e^{-2k\pi \theta} \cdot e^{i\theta}$ does not hold for all $k \in \mathbb{Z}$. What is going on here?   Also $e^{i \theta}$ is supposed to take infinitely many values since the exponent is neither a real integer, nor a rational fraction. Which way is it?  EDIT:  If I input $e^{\pi i}$ to Wolfram Alpha:    I get both a single valued result -1 and a multivalued result.

If we define  $$e^z=1+z+\frac{z^2}{2!}+\cdots$$  then it is single-valued.  However, if we write  $$e^z=e^{z\ln e}$$  then it is multi-valued.  Besides, $a^z$ is multi-valued in general. It is kind of strange if only when the base is $e$ that it is single-valued.  My thought: Is it true that there are two exponential functions, let's call them $\exp(z)$ and $e^z$?  Where $\exp(z)$ is defined by  $$\exp(z)=1+z+\frac{z^2}{2!}+\cdots$$  and is single-valued, while $e^z$ is defined by  $$e^z = \text{exp}(z\ln e)$$  and is multi-valued?  Here $\ln z$ is defined by $\exp(\ln z)=z$ and is multi-valued.


The program is designed to scan the user for the first two cards they receive and tell them what they have. Unfortunately, when it asks "Are the cards suited?: " it terminates before input can be taken. I also could learn how to organize the conditions in a switch statement rather than all these ugly if-else statements as well.   package Test; import java.util.Scanner; public class Test { public static void main(String[] args) {              // TODO Auto-generated method stub             int card1 = 0;             int card2 = 0;             String fc1, fc2;             String answer;               Scanner scan = new Scanner (System.in);             System.out.println("First card: ");             if (scan.hasNextInt())             {                     card1 = scan.nextInt();             }             else             {                     fc1 = scan.next();                      if (fc1 == "A")                     {                             card1 = 14;                     }                     else if(fc1 == "K")                     {                             card1 = 13;                     }                     else if (fc1 == "Q")                     {                             card1 = 12;                     }                     else if (fc1 == "J")                     {                             card1 = 11;                     }             }              System.out.println("Second card: ");             if (scan.hasNextInt())             {                     card2 = scan.nextInt();             }             else             {                     fc2 = scan.next();                     if (fc2 == "A")                     {                             card2 = 14;                     }                     else if (fc2 == "K")                     {                             card2 = 13;                     }                     else if (fc2 == "Q")                     {                             card2 = 12;                     }                     else if (fc2 == "J")                     {                             card2 = 11;                     }             }           if (card1 == card2)           {              System.out.println("You have a pair.");          }          else           {         System.out.println("Are your cards suited?(y/n): ");         answer = scan.nextLine();               if (answer == "y")              {                  if (card1 >12 && card2 > 12)                  {                      System.out.println("High value suited cards.");                  }                  else                      if (card1 == card2++ || card1++ == card2)                      {                          System.out.println("Suited connectors.");                      }              }              else                  if(answer == "N")                  {                      if (card1 >=12 && card2 >= 12)                      {                          System.out.println("High value cards, hold.");                      }                      else                          if(card1 > 5 && card2 > 5)                          {                              if(card1++ == card2 || card1 == card2++)                              {                                  System.out.println("Connectors.");                              }                              else                              {                                  System.out.println("Fold");                              }                         if (answer != "y" || answer != "n")                         {                                 System.out.println("Invalid entry.");                         }                      }              }             }              }                   }

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?


I was going through the section on Binomials in Mathematics: Analyses and Approaches (IB). The author stated the expansion of $(1+x)^n$ as follows:  $$ (1+x)^n = { {{n} \choose {0}} + {{n} \choose {1}}x + {{n} \choose {2}}x^2 + \;...\; + {{n} \choose {n}}x^n} $$  Then, he said that it could be used to prove the following relationships/equations:  $$ 2^n = { {{n} \choose {0}} + {{n} \choose {1}} + {{n} \choose {2}} + \;...\; + {{n} \choose {n}}} $$  $$ 0^n = { {{n} \choose {0}} - {{n} \choose {1}} + {{n} \choose {2}} - {{n} \choose {3}} + \;...\; + (-1)^n{{n} \choose {n}}} $$  I was able to derive these relationships on my own, but got stuck on the expansion of $4^n$, here is the result, based on the original expansion of $(1+x)^n$. Could someone please explain how to derive this? $$ 4^n = { {{2n+1} \choose {0}} + {{2n+1} \choose {1}} + \;...\; + {{2n+1} \choose {n}}} $$

I've worked out a proof, but I was wondering about alternate, possibly more elegant ways to prove the statement. This is my (hopefully correct) proof:  Starting from the identity $2^m = \sum_{k=0}^m \binom{m}{k}$ (easily derived from the binomial theorem), with $m = 2n$:  $2^{2n} = 4^n = \binom{2n}{0} + \binom{2n}{1} + \cdots + \binom{2n}{2n-1} + \binom{2n}{2n}$  Applying the property $\binom{m}{k} = \binom{m}{m-k}$ to the second half of the list of summands in RHS above:  $4^n = \binom{2n}{0} + \binom{2n}{1} + \cdots + \binom{2n}{n-1} + \binom{2n}{n} + \underbrace{\binom{2n}{n-1} +\cdots \binom{2n}{1} + \binom{2n}{0}}_{\binom{m}{k} = \binom{m}{m-k} \text{ has been applied}}$  Rearranging the above sum by alternately taking terms from the front and end of the summand list in RHS above (and introducing the term $\binom{2n}{-1} = 0$ at the beginning just to make explicit the pattern being developed):  $4^n = (\binom{2n}{-1} + \binom{2n}{0}) + (\binom{2n}{0} + \binom{2n}{1}) + \cdots + (\binom{2n}{n-1} + \binom{2n}{n})$  Finally, using the property $\binom{m}{k} + \binom{m}{k-1} = \binom{m+1}{k}$ on the paired summands, we get the desired result:  $4^n = \binom{2n+1}{0} + \binom{2n+1}{1} + \cdots + \binom{2n+1}{n}$


Good Day!  I Need help with a Libgdx Project. What i want is to remove a tile, which is in my graphics layer (layer 0).  This is what i got so far:  if(object1.getUserData() != null && object1.getUserData() == "polyblock"){        polyblock1 = true;        System.out.println("PLAYER 1"); }else if(object1.getUserData() != null && object1.getUserData() == "redcoin" || object1.getUserData() == "greencoin" ||  object1.getUserData() == "bluecoin" ){            B2dObjectGetter.getCell(object1.getUserData() == "redcoin" ? 3 : object1.getUserData() == "greencoin" ? 4: 5).setTile(null);       }   The coin bodies and the getCells Method:  for (int i = 3; i <= 5; i++){      for (MapObject obj : map.getLayers().get(i).getObjects().getByType(EllipseMapObject.class)) {             Ellipse ellipse = ((EllipseMapObject) obj).getEllipse();              bdef.type = BodyDef.BodyType.StaticBody;             bdef.position.set((ellipse.x + ellipse.width / 2) / GameJLibGDX.PPM, (ellipse.y + ellipse.height / 2) / GameJLibGDX.PPM);              CircleShape shape = new CircleShape();              coinbodies[i] = world.createBody(bdef);             shape.setRadius(ellipse.width / 2 / GameJLibGDX.PPM);             fixdef.shape = shape;             coinbodies[i].createFixture(fixdef).setUserData(i == 3 ? "redcoin" : i == 4 ? "greencoin" : "bluecoin");         }     }  }  public static TiledMapTileLayer.Cell getCell(int i){     TiledMapTileLayer layer = (TiledMapTileLayer) map.getLayers().get(0);     System.out.println(coinbodies[i].getFixtureList());     return layer.getCell((int)(coinbodies[i].getPosition().x * GameJLibGDX.PPM / 128),(int)(coinbodies[i].getPosition().y*GameJLibGDX.PPM / 128)); }   It seems to work really fine except one Thing:  Blue coin got hit:    Green coin got hit:    Red coin got hit: Cant post more than two Pictures :(. The red coin is disappering and everything is fine. But only if I hit them one after another. So i mean in the order: Redcoin, Greencoin, Bluecoin  I noticed something really weird:    but:    Thank you for your time!


Ran into the 260 character file path limit today, did some googling and found  article describing how to remove the limit. Followed the steps for group policy (I have Windows 10 Pro) and then restarted.  Edit: looked in the registry path mentioned in the article. The value is already set to 1  However, the problem still occurs, and I can't create the files because the "filepaths(s) would be too long".  I'm running Windows 10 Pro Build 14393.953.

I updated to the Windows 10 home anniversary edition version 1607 and set LongPathsEnabled to 1 with regedit.exe but the File Explorer doesn't seem to work with long paths still. If you select a long path file and try to rename it, no option will be available. I restarted the computer after making the changes and update.   Is there any way to enable renaming in the File Explorer in the new updated version? Did I miss a step somewhere?


My old xournal is 0.4.5, which is /usr/bin/xournal. I just installed a new version 0.4.8 by compiling from source to /usr/local/bin/xournal.  When I call xournal directly from the terminal, it is the old version.  $ xournal   When I call /usr/local/bin/xournal, it is the new version.  $ /usr/local/bin/xournal    But which shows that xournal is /usr/local/bin/xournal  $ which xournal /usr/local/bin/xournal   Isn't which supposed to show the actual path when calling xournal?  My PATH puts /usr/local/bin before /usr/bin, so why doesn't calling xournal  call /usr/local/bin/xournal but /usr/bin/xournal?  $ echo $PATH ”/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games”    Thanks.

When I execute a program without specifying the full path to the executable, and Bash must search the directories in $PATH to find the binary, it seems that Bash remembers the path in some sort of cache. For example, I installed a build of Subversion from source to /usr/local, then typed svnsync help at the Bash prompt. Bash located the binary /usr/local/bin/svnsync for "svnsync" and executed it. Then when I deleted the installation of Subversion in /usr/local and re-ran svnsync help, Bash responds:  bash: /usr/local/bin/svnsync: No such file or directory   But, when I start a new instance of Bash, it finds and executes /usr/bin/svnsync.  How do I clear the cache of paths to executables?


I'm having trouble proving the following equation:  $$\lim_{n→∞}\left(\frac{∑^{n}_{k=1}k^{m}}{n^{m+1}}\right)=\frac{1}{(m+1)}$$  A link to a proof would suffice. Thank you.

What is the result of the next limit:   $$ \lim_{n \to \infty} \frac{ \sum^n_{i=1} i^k}{n^{k+1}},\ k \in \mathbb{R} $$  Why (theorem)?


So, I'm starting out my first project in VS2010, and I see that I can drag and drop files into the project tree, lovely. However, this doesn't resolve missing includes? I'm assuming it's not good form to put all the header files in the same folder as the source code files. Yes, I know there's such a thing as an include environment variable, but surely I'm not expected to store all the headers for every project I ever do in there, until the end of time?  Clearly I'm misunderstanding something. Please be gentle, new to C++ as well.

I checked out a copy of a C++ application from SourceForge (HoboCopy, if you're curious) and tried to compile it.  Visual Studio tells me that it can't find a particular header file. I found the file in the source tree, but where do I need to put it, so that it will be found when compiling?    Are there special directories?


If you shine a flashlight pointing outwards inside a black hole, would the photon go down to the singularity? Is there any way to visualize the path of a photon going to the singularity, or would that path be irrelevant because the singularity is in all directions?

$$ A $$  Light is travelling away from the absolute center of the Schwarzchild black hole (i.e. none of that spinning/stretching field) at $\ C $, and so shouldn't $\ \Delta C$ need to be greater than $\ C $ in order for the light to collapse into the black hole, therefore violating the relativistic limit of $\ C $?    It seems like light would just 'hover' right in the center of a black hole then. Because if it goes away from it, the event horizon pulls it back, and if it goes into it, the velocity change must be greater than $\ C $ which violates general relativity; so technically there's no way for the light to move away, and so it would just be still.  The thing is that the light must move at the speed of light or general relativity doesn't work. It's massless... But in the center of a black hole, if the above is true (it can't move or escape), then it is not travelling at the speed of light. So it cannot be still.  It cannot be spinning in a constant orbit either, because that would require velocity in an outward angle. And it cannot move in an outwardly fashion, only in an inwardly one.  Is it spinning in an infinitely decaying spiral towards the center?  If so what happens to it if and when it reaches the direct and complete center, i.e. The case of it being 'shot' from the center.    $$ B $$  If you shot light at an angle towards a black hole, but not directly to the center of it  then that light from the outside will eventually become the same as the light that I said was shot from the center to the outside; because in both cases, they end up in an infinitely decaying spiral.    If so it would end up exactly like the light in the above paragraph, so then we need to figure out what happens to that light to figure this one out, or vice versa.    $$ C $$  If you shot light directly towards the center of a black hole it would have no spiral to decay into, so therefore it must stop at some point in the center of a black hole. If it stops though, it loses it's momentum and violates general relativity again because it's energy "disappears".    If so then it violates conservation laws. So I'm assuming this simply is not true.    Is the light travelling into a black hole somehow still travelling at the speed of light, in every direction possible where that direction keeps it facing towards the center?  If so, why is there not a point at which the only thing left for the light to do is stay still, since all other paths would increase the distance between it and the black hole's center, and therefore become Case A. And if there isn't, what would happen if there was?  Also, if it's a time and observation answer where it supposedly takes and infinite amount of time for C to hit the center, wouldn't it be the case that the black hole is 'eating' all of the available light in the universe and keeping it in stasis?  Also, what happens in a Kerr black hole then? Does it just rip the field of time/gravity at an angle such that the light would never get closer than the center?


In other words, what is the largest clique that can be drawn without any crossing edges in $\mathbb{R}^n$?  It's trivial in $\mathbb{R}$: 2.  In $\mathbb{R}^2$: 4, as we know that $K_5$ is non-planar  But what if we take it further to $\mathbb{R}^3$ and beyond? I can imagine at least a planar clique of size 6 in $\mathbb{R}^3$ by adding a vertex "above" and "below" the planar form of $K_4$ and adding edges appropriately. But is that the limit? Is there a general law for $\mathbb{R}^n$?

When adding nodes to a graph with a restriction that all nodes in the graph have a direct connection to all other nodes, how can one detect when a higher dimension is needed so the edges do not cross each other? By crossing I mean one can stretch an edge, circle around all other nodes and not touching any other edge.  For example, three nodes form a triangle and can reside in a 2D plane. Adding one node you can still put four nodes in a 2D plane without crossing edges. But adding the fifth node you have to go to 3D to avoid edge crossing.  It seems like any time a prime number of nodes is added the dimension needs to bump up.


For the past 3 weeks, I have been getting this BSOD error on my laptop: Driver State Power Failure.  I have , but I have no idea how to analyse them.  I am not able to find the problematic driver, so I thought I should reset them all.  How can I reset them to factory versions?

For the past two weeks, I've been getting this BSOD error on my Lenovo laptop. I have even reset my laptop ("rest this PC"), but it's still happening.  My laptop details:     I have the latest Nvidia driver for my Nvidia Geforce MX150: 431.60 released on 23 Jul 2019.  I have the latest BIOS for my laptop: 8TCN53WW15  released on 15 Jul 2019.     I have run WhoCrashed, it says it says the problem was caused by some driver which could not be identified. If I get to know the problematic driver I will update/uninstall it.  How can I analyze my dump files, so that I can find the problematic driver?  Edit 1: If you get "Oops there was a problem with the network" on google drive page while accessing dump files, just click on download. They will be downloaded. I don't know what's causing this.