I got a new PS3 recently and previously I used my brothers PS3 with my own account anyways I want to transfer all my stuff onto the new one. I really don't wanna start over on all my games and plus I spent a lot of money on games I bought on the play station store so how do I get them to the new PS3... Sorry if I'm typing a lot I just want to get the right answer. Like I said before I really don't wanna start over with all my games so idk how to get the saved data onto the new one. Thanks for your help I really appreciate it   Btw I have a large USB hard drive that I could use Im not sure if that'll help or anything and I think there might be a way to transfer everything using ps+ but I don't know how I would do that..


Is Stack Exchange in violation of New York labor law, in using volunteer moderators? I found a  document, which states:  Q: Can for-profit and non-profitmaking institutions have unpaid volunteers? A: By definition, the term volunteer means a person who works for a non-profitmaking institution under no contract of hire…and with no promise of compensation, other than reimbursement for expenses as part of the conditions of work. A person may do volunteer work in a non-profit organization, if that organization is set up and operates strictly for charitable, educational or religious purposes. For-profit organizations may not use unpaid volunteers (who meet certain criteria) except for a short term recreational or amusement event run by that organization.  Am I drawing the correct conclusion, that actually a for-profit organization, such as Stack Exchange, is not permitted, under New York State labor law, to use volunteer labor for moderation tasks?  Related:


Wordpress speed slow after .5 million single image post via wp-cli

I am trying to Creat Wordpress website that will contain 10 Million post, such that when i upload a single its become a post with it's own name as title.  and i am importing these images with Wp-cli. now the problem i am facing is that i have uploaded about half a million images and now Wordpress has become slow, its taking too much time to import images. please suggest me any solution for this   Images Importing goes slow down, Server usage only 1% i am doing this Via WP-cli with this command  wp media import ~/Pictures/processed-images-medium/\*\*\/\*.jpg   every time when image upload its become a Unique post you can check it at here  http://www.wallpaper2k.com/naked-art-first/


Does there exist a GCD domain $R$ in which the relationship $aR \cap b R \subseteq \mathrm{lcm}(a,b) R$ is untrue?

Question. Does there exist a GCD domain $R$ in which the equation $aR \cap b R \subseteq \mathrm{lcm}(a,b) R$ is untrue?  Remark. The superset direction is always true: since $a \mid \mathrm{lcm}(a,b)$, thus $a R \supseteq \mathrm{lcm}(a,b)R.$ Similarly since $b \mid \mathrm{lcm}(a,b)$, we deduce $bR \supseteq \mathrm{lcm}(a,b)R$. Combining these results, we infer that $aR \cap b R \supseteq \mathrm{lcm}(a,b) R.$


Why do some Area 51 profiles not have a network profile?

I was  stalking searching some user profiles under new proposals on Area 51. I found some accounts do not have a network profile page. If we click on Network profile in the profile page in Area 51, we are taken to  with a sign post of a Panda.   If it helps, it is frequently seen in new user accounts aged 1 or 2. Does it happen if the user only has an account on Area 51 and not anywhere on the network or some other reason?  Initially I thought  are only ones with this problem but even some  also take to Page Not Found (Thanks to Rob).  Why is Network profile "Page Not Found"?


How to replace regex in all files that match this regex

Let's assume that I have some files(in a directory tree - for example, ~/home) that may something I am looking for: e.g. I'm looking for a string a.2 and I want to change it for b.3. I know that I can list them by running grep -R 'a\.2' *. This will show me matches, prepended with filenames. However, I don't know how to replace them. How can I do that?


What is the notation for total number of rows in a matrix M?

Consider a matrix M(i,j). It has n columns and m rows. How do I indicate m rows for matrix M? What is the notation?


Editing capabilities document in GeoServer

I've got several layers in GeoServer, one of which I'm trying to use as a WMS in desktop programs (Manifold 8). I've set it up correctly, but whenever I bring it into Manifold, it projects the layer into EPSG:4326, which unfortunately can't work with my map - I need it in EPSG:3857. The layer in question is wrapped inside a more overarching layer definition, which contains all the layers - and coordinate systems that allow them all to be used flexibly. However, I want to put this layer on its own in the capabilities document, and only allow it to use EPSG:3857. How, in GeoServer, would I edit, or override, a capabilities document?


Cannot see my wifi [10ec:d723] when trying Ubuntu

I am having an issue with wifi; it seems when I'm trying Ubuntu without installing, it only detects connection via the ethernet cable.  I can't connect and none of the available wifi networks are detected.  $ lspci 00:00.0 Host bridge: Intel Corporation Device 5904 (rev 02) 00:02.0 VGA compatible controller: Intel Corporation Device 5916 (rev 02) 00:04.0 Signal processing controller: Intel Corporation Skylake Processor Thermal Subsystem (rev 02) 00:08.0 System peripheral: Intel Corporation Sky Lake Gaussian Mixture Model 00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21) 00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21) 00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI (rev 21) 00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21) 00:1c.0 PCI bridge: Intel Corporation Device 9d10 (rev f1) 00:1c.4 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1) 00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port (rev f1) 00:1f.0 ISA bridge: Intel Corporation Device 9d4e (rev 21) 00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21) 00:1f.3 Audio device: Intel Corporation Device 9d71 (rev 21) 00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21) 01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Sun XT [Radeon HD 8670A/8670M/8690M / R5 M330] (rev 83) 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15) 03:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device d723     $ lspci -knn | grep Net -A3 03:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:d723]     DeviceName: Hanksville Gbe Lan Connection     Subsystem: Hewlett-Packard Company Device [103c:8319]


How do I set Windows to boot as the default in the boot loader?

How do I set the bootloader so that in my dualboot with Windows 7/Ubuntu 11.04, Windows start up as standard instead of Ubuntu?


I am trying to grab the extension of an uploaded file and echo it back on my page.  $file_name = $_FILES['profile_pic']['name']; $file_extn = end(explode('.', $file_name)); $file_temp = $_FILES['profile_pic']['tmp_name'];  echo $file_extn;   The error I am receiving is      Strict Standards: Only variables should be passed by reference in C:\xampp\htdocs\reptile_forum+help\includes\widgets\logged_in.php on line 67.   Line 67 is the "$file_ext ="  Am I not using end() properly? Is there something else I can use to get me the same result?  Note: The array displays perfectly when I remove end() and use print_r(), it just seems as though end() isn't registering the array or something like that.


Windows 10 Start menu, notification center, store apps not working

Everything in Windows 10 worked perfectly for just 3 or 4 days after upgrading from 8.1. Yesterday I wanted to use the search feature, so I press win+s and get the error "Critical Error: Your Start menu isn't working. We'll try to fix it the next time you sign in."  (I also can't open the settings app since that's also a 'metro' app)  I have tried everything I could find and nothing worked for me.  Things I've tried include:   In powershell:   Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}  The answer .   And things like that.  "Did you modify the registry?"  Yes:   Adding Sublime Text 3 to the "Open with" list (It can't be because of this can it?) Back in Windows 8; Adding a few things to the RMB menu of some files (no trouble at all)   So what can I do to fix these problems?


The error: "mount: only root can do that" while mounting a partition

I've installed Ubuntu 12.04 along with Windows 8.1. When I tried to open the C: drive in Ubuntu a window is popping out saying to run this command:  mount -t ntfs-3g -o remove_hiberfile /dev/sda2 /media/2A36EE3236EDFEA7   After running the command I'm getting the error mount: only root can do that.   What should I do?


In STL maps, is it better to use map::insert than []?

A while ago, I had a discussion with a colleague about how to insert values in STL . I preferred map[key] = value; because it feels natural and is clear to read whereas he preferred map.insert(std::make_pair(key, value)). I just asked him and neither of us can remember the reason why insert is better, but I am sure it was not just a style preference rather there was a technical reason such as efficiency. The  simply says: "Strictly speaking, this member function is unnecessary: it exists only for convenience." Can anybody tell me that reason, or am I just dreaming that there is one?


Why does Walter White wear the hat everytime when he acts like Heisenberg?

In Breaking Bad, why does Walter White wear the hat everytime when he acts like Heisenberg? Does it symbolize his attitude or something else?


Applying class to dynamic element in jquery

Iam creating a dynamic input and applying a class to it, but its not working. My class:  $(".numeric_input").keypress(function(e) {     var a = [];     var k = e.which;     for (i = 48; i < 58; i++)        a.push(i);     if (!(a.indexOf(k)>=0))        e.preventDefault(); });   My code:  var table = document.getElementById('sizeTable'); for(var i=0;i<sizes.length;i++) {     $("	").html('<input type=text class=numeric_input name=rows['+i+'].quantity>').appendTo(tr);     $(tr).appendTo(table); }   The same class applied to other elements are working fine. Any help


I upgraded from Ubuntu 19.10 to 20.04. Many articles mention that the latest LTS will not support python2. But I still have it. Why is that?  $ python Python 2.7.18rc1 (default, Apr  7 2020, 12:05:55)  [GCC 9.3.0] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> print "hello world!" hello world! >>>


Stained Glass Cheat to Transform into Clear Glass

Is there a Minecraft command that transforms all Stained Glass in the world into normal Clear Glass? I built a structure with Stained Glass but I don't like the colours. Does anyone know how to change this?


What is the C# Mathf.Lerp equivalent in Python?

I have a basic menu script with a slider. The idea is that the slider will control the rotation of a bone. That bone will then rotate the object. I worked out the exact euler angles to rotate it by, and now I'm a little bit stuck. I've used C# for quite some time and C# has this thing called , and I wondered if there is a python equivalent? If so, what is it?  Here is what I'm aiming for:  elif origin == 'screen_rotation':     bones = bpy.context.object.pose.bones      Mathf.Lerp(bones["Screen"].rotation_euler[1] = 0, bones["Screen"].rotation_euler[1] = 1.58825, screen_rotation)


Does the given matrix have a square root?

Given the following matrix, I was asked to tell whether the matrix is the square of some matrix or not.  $$ \begin{pmatrix} 1 & 0 & 0\\ 0 & -1 & 0\\ 0 & 0 & -1 \end{pmatrix} $$  Since this matrix is diagonal, a square root is  $$ \begin{pmatrix} 1 & 0 & 0\\ 0 & i & 0\\ 0 & 0 & i \end{pmatrix} $$ Am I right?


I am working with JasperReports and iReport tool. One of the requirements the client wants is that the PDF file will be generated to a 100 page document only.   Could you please help me? How can I generated the 100 page PDF document?


Could a site be created that does not collect PII?

Last fall, Tim Post ♦  that the primary reason that the accounts of underage users are deleted on sight is that there are laws against holding a minor's Personally Identifiable Information (PII). This has caused some consternation among both child users who have been banned and adult users who appreciated the contributions of child members that have been banned due to their age.  That rigamarole has led me to come up with the idea of proposing a programming site for underage users (tentative name: Stack Overflow for Teens) that would be more or less like a "regular" Stack Exchange site but where no PII would be collected from participants, or at least the gathering of PII would be completely voluntary and underage users found to have disclosed PII could continue participating after their PII was deleted (and perhaps a short suspension to teach them a lesson, especially if they have continued to provide PII after being warned that they are not old enough to do so).  Is a site that does not collect PII feasible? I have not (yet) proposed such a site because I (currently) lack the . The fact that underage users can't come onto the current Area 51 obviously doesn't help much, but that's not the focus of my question. I'm not asking about finding a community, but if I could find enough sympathetic adults to push through a proposal for a site for underage users, is this something that would be feasible or would Stack Exchange the company be likely to shoot it down as unfeasible either in a technological or business sense? E.g. "This is a great idea, but I have to close this proposal because the programming effort to remove all mandatory PII collection points would cost more than the company has, and the company's model anyways involves the monetization of PII so there's really little reason we would want this."


To improve first poster experience, can questions have a suspend state before they can be voted for close?

Possible names for this feature:  "Suspended" "Under review"  I am sure newbies find it quite confronting to ask a question and then have it "closed". A suspend state would be more friendly:  "Suspension" feels less "permanent" than "close" A novice poster will feel like they have an opportunity to rectify it (unlike the feeling of "closed") A novice poster will feel more welcome in the SE community Those with fewer credibility points may have right to moderate suspensions, adding more people to that review queue, leading to faster response after a novice rectifies More automation should be possible, because false-positives of "suspension" are not as confronting as a false-positive of "close". Thereby, more suspension/unsuspension can be actioned faster with smaller queues for moderators, and a fast response for novices, being a friendlier experience.  I think it would be simpler if there was a "suspend" state for questions instead.  We probably wouldn't need  We probably wouldn't need  We probably wouldn't need  We probably wouldn't need   What other feature requests could be nullified by this idea? Design:  There should be fewer votes to suspend - making administration lighter It should unsuspend after being edited by the OP or another editor A suspended question MAY BE closed automatically by the system if left unedited after suspension for X days The usual close rules will apply, but likely with fewer votes needed for closing/reopening, but more review queue work to be focused on the suspend/unsuspend than on closing/reopening People should still be able to post answers. Such answers can help show a reviewer (who doesn't understand the niche technology) whether it is a more specialised Q/A or whether it truly is duplicate. The ability to still get answers for a "suspended" question would be much more friendly to novices and those answering alike  Is this a good design?


I am very new to Latex and I have a file I need to compile. When doing so I get the message: The required file tex\latex\arabi\bblopts.cfg is missing. It is a part of the following package: arabi".  I hit install and install the package. However, the next time I compile the file I get the same message over and over.  What is the issue?  I also attached message screenshot


Permission denied when running make install

I'm trying to install llvm. I cloned the repository and ran ./configure. Now, I need to run sudo make install. When I run this, I get the following errors:  harshilsharma63@ubuntu:~/llvm$ sudo make install [sudo] password for harshilsharma63:  llvm[0]: Installing include files make: execvp: /home/harshilsharma63/llvm/autoconf/mkinstalldirs: Permission denied make: *** [install-local] Error 127 harshilsharma63@ubuntu:~/llvm$ sudo make install llvm[0]: Installing include files make: execvp: /home/harshilsharma63/llvm/autoconf/mkinstalldirs: Permission denied make: *** [install-local] Error 127   I have installed build-essentials. I cloned the repository using svm in fedora and copied the downloaded files from Fedora -> Windows -> Ubuntu.  Note: I'm using Ubuntu 12.04


TexStudio with Jabref: compilation fails

I am using TexLive 2015 with TexStudio. I am editing my bibliography with Jabref.   I recently updated TexStudio and face bibliography compilation troubles since then.  When I compile, the log file indicates: "empty bibliography" and "undefined references". I guess this is due to an error in the path between Jabref and texstudio or a wrong setting in TexStudio. I changed the default bibliography tool in Texstudio to put Biber rather than Bibtex but the compilation doesn't work whatsoever. My JabRef-generated literature file (thesegain2017.bib) is saved in the same folder than my tex-files.   My knwledge stops right here. Would someone have any idea on how to work this out? Many thanks !  Below my minimal working example:  \documentclass[french]{article} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{lmodern} \usepackage[backend=biber,style=verbose-trad1, ibidtracker=context]{biblatex} \renewcommand{\mkibid}[1]{\emph{#1}} \usepackage{csquotes} \usepackage[perpage]{footmisc} \addbibresource{thesegain2017.bib} \usepackage[a4paper]{geometry}  \usepackage[english,francais]{babel}  \begin{document}  Blalalblla\autocite{Bourdieu1979}  \printbibliography  \end{document}   Here is the .bib file:   % This file was created with JabRef 2.10.  % Encoding: UTF8  @Book{Bourdieu1979,   Title                    = {La distinction, Critique sociale du jugement},   Author                   = {Bourdieu, Pierre},   Year                     = {1979},   Location                 = {Paris},   Pagetotal                = {670},   Publisher                = {Les éditions de Minuit},    Owner                    = {Mailys},   Timestamp                = {2014.05.14}  }   In the .bbl file I found that:   % $ biblatex auxiliary file $ % $ biblatex bbl format version 2.5 $ % Do not modify the above lines! % This is an auxiliary file used by the 'biblatex' package. % This file may safely be deleted. It will be recreated by % biber as required.  \begingroup \makeatletter \@ifundefined{ver@biblatex.sty} {\@latex@error {Missing 'biblatex' package} {The bibliography requires the 'biblatex' package.}   \aftergroup\endinput} {} \endgroup   But in the .blg file, I found that:  [0] 05015a72.pm:324> INFO - This is Biber 2.1 [0] 05015a72.pm:327> INFO - Logfile is 'my file.blg'


Kali linux doesnt show new updates and upgrades

I have my old 2016.2 kali version on usb stick.I installed it on dual boot. I ran uname -a in terminal and got output: Linux kali 4.6.0-kali1-686-pae #1 SMP Debian 4.6.4-1kali1 (2016-07-21) i686 GNU/Linux which i suppose is kali 2016.2. But when i do sudo apt-get update; sudo apt-get upgrade and sudo apt-get dist-upgrade it doesn't install anything. And 2017.1 is out.


Are questions on Jobs (formerly Careers) off-topic at Meta Stack Exchange?

From  it appears that the Meta site for Jobs (formerly Careers) is now  but I do not recall that being written here on Meta Stack Exchange in other than a comment or two.  Are questions on Jobs (formerly Careers) now off-topic here at Meta Stack Exchange?  I think they must be because some recent questions on that topic have been migrated from here to :       Looking for guidance I found  but it seems concerned with arrangements for Careers rather than Jobs, and thus to be outdated.


How does delete[] "know" the size of the operand array?

Foo* set = new Foo[100]; // ... delete [] set;   You don't pass the array's boundaries to delete[]. But where is that information stored? Is it standardised?


Japanese storing SQL Server and display PHP

I have problem with Japanese Characters. I want to store Japanese Characters into a SQL Server database. When I try to display in Terminal it's good but when I try in HTML page Japanese characters are replace with question marks. I don't understand why it's work in console and not in web browser.  I try to change collation for the database, change charset to html page, without any effect  How can I fix that?  Thanks


Exact form of distance preserving map $T:\mathbb R^2 \to \mathbb R^2.$

Let $T:\mathbb R^2 \to \mathbb R^2$ be distance preserving, i.e., $|T(a)-T(b)|=|a-b|$ for all $a,b\in \mathbb R^2.$ From here can we say the exact form of $T$?   If $T(x)=Ax+b,$   where $A^TA=I$ and $x,b\in \mathbb R^2$ and $b$ is fixed, then $T$ is distance preserving.  But my question is that 'Can we say that the above mentioned mappings are only distance preserving map?'


How to open the Preview window maximised by default?

Does anyone know how to open Preview.app with the window maximised by default, in order to automatically fit the screen?  Right now, the Preview window opens almost half screen and I think it is quire annoying to enlarge it manually. Thanks.


John: "I gave the waiter a $50 dollar tip and he gave me a dirty look. Maybe I should have given him more?" Bill: "No, $50 is enough, I would have thought." Should it be: "No, $50 was/would be enough, I would have thought"?


How does `(sum & operand) === operand` work in the following code? (Bitwise And)

The following code checks if sum has operand, the code is very straightforward, but I'm confused by the condition (sum & operand) === operand. I've read the  doc, confused me even more, can someone explain it in simple terms? const has = (sum, operand) => (sum & operand) === operand  console.log(has(7, 4))


Running a script during booting/startup; init.d vs cron @reboot

I am currently trying to understand the difference between init.d and cron @reboot for running a script at startup/booting of the system.   The use of @reboot (this method was mentioned in  by hs.chandra) is some what simpler, by simply going into crontab -e and creating a @reboot /some_directory/to_your/script/your_script.txt and then your_script.txt shall be executed every time the system is rebooted. An in depth explanation of @reboot is   Alternatively by embedding /etc/init.d/your_script.txt into the second line of your script ie:  #!/bin/bash # /etc/init.d/your_script.txt  You can run chmod +x /etc/init.d/your_script.txt and that should also result for your_script.txt to run every time the system is booted.  Q1: What are the key differences between the two? Q2: Which is more robust? Q3: Is there a better one out of the two? Q4: Is this the correct way of embedding a script to run during booting?  I will be incorporating a bash .sh file to run during startup.


Where can I obtain an English dictionary with structured data?

I would like to download an English dictionary -- not just a  -- in a structured format such as TXT, XML, or SQL.   Specifically, I need phonetic pronunciation and parts of speech (definition is not required).  Surprisingly, I can't find this online anywhere.  is available , but it only the mediawiki articles themselves. Crawling all articles and extracting the phonetics and parts of speech would be a huge exercise.   Is this available anywhere? I don't mind paying.   Note: cross-posted .


When I do a branded search for a website the structure shows like ( see image ). I would love to remove Privacy Policy page or Manipulate the structure I see now ( showing pages I want to ). How I can do it?     I already added robots - nosnippet meta tag to remove all rich snippets from a page, but it didn't work. Are there any other methods except removing page from indexation?


I have a script that calls an application that requires user input, e.g. run app that requires user to type in 'Y' or 'N'. How can I get the shell script not to ask the user for the input but rather use the value from a predefined variable in the script?  In my case there will be two questions that require input.


I know that many people believe that math is discovered, but here I want to know if pure mathematics, in specific, is discovered or invented and why. There are definitely many arguments to both sides. Personally, I believe that pure math is discovered but my mind could be changed. I know that pure math has gone a bit too abstract recently, but I don’t believe that it makes it any less a discovery. When something is invented there is possibility that the results could have been different depending on the organism that invented it. I don’t think that this applies to math because any organism anywhere would come to the same conclusions. I would love to hear a second opinion.


Position of superscript when superscriptd item has \hat over it

I am trying to typeset he following inline math for a camera-ready document:  $\hat{\boldsymbol \Sigma}_{P}^{-1} \hat{\boldsymbol \Sigma}_{G}$   It appears that the superscript -1 is aligned considering \Sigma and the \hat symbol as  complete item. This increases the line spacing. What I would like to typeset is the -1 aligned with \Sigma only, i.e. to move it downward a little. Is that feasible and, if so, how can this done?


Is someone trying to hack into my server? What can I do?

A few weeks ago I posted a question here about some ssh issues I was having with an Ubuntu 12.04 box. Fast forward to today and I am trying to allow someone else access to the machine, but they keep getting password errors. I checkout out var/logs/auth.log for more info, and found this:  May 11 19:45:33 myserver sshd[9264]: Did not receive identification string from 211.110.xxx.x May 11 19:45:38 myserver sshd[9267]: Did not receive identification string from 211.110.xxx.x May 11 19:45:44 myserver sshd[9270]: Did not receive identification string from 211.110.xxx.x May 11 19:45:49 myserver sshd[9274]: Did not receive identification string from 211.110.xxx.x   I have almost 10000 lines that all seem to say more or less the same thing (there are also 4 auth.log.gz files, which I'm assuming are more of the same?). Sometimes there is a random username attached to the request, input_userauth_request: invalid user bash [preauth]  I don't know much about servers, but it looks like someone is trying to gain access to mine.  Googled around for how to block an IP address in Ubuntu and ended up with this: iptables -A INPUT -s 211.110.xxx.x -j DROP, but after running that command and checking the logs, I'm still getting requests from this one IP every 5 seconds.   How can I find out more about what's going on and deal with these constant requests?


History list without timestamp and unique the results

Using bash, I save my history with the timestamp.   How do print the history omitting the timestamp?   alias h=history alias g=grep -i   To find lines that I used for heroku, I type:  > h | g heroku   I'd like to unique the results without the time-stamp, naturally.  This question is somewhat related:   However, sometimes I want to see the duplicate in the history to see the context under which a command was run.


(block) size of /dev, /etc, /proc, /home, explanation?

Can somebody explain, why a standard folder has always 4kB and some special directories have more or less?  some examples:   /dev   3280B, 0 Blocks, 16 Links /etc   12288B, 24 Blocks, 119 Links /proc  0B, 0 Blocks, 85 Links /home  4096B, 8 Blocks, 4 Links


What is the interstellar density of mm sized "dust" particles?

If you assume an interstellar spacecraft of 100 m in diameter traveling to the nearest star - that ship would plow through 3 x 10^20 m^3 of interstellar space.  At 0.5 c the energy release of such a spaceship encountering a piece of space "dust" weighing (~0.01g) becomes significant. Only one such impact would be enough to cause severe spacecraft damage given the kinetic energy involved (150,000 Joules).  This collision would explode like a pinpoint bomb (30 g of TNT - one half the charge in a hand grenade).  So, what are the chances of such a space ship encountering such a interstellar grain of dust in traveling to the nearest star?


I feel like I've fallen at the first hurdle, importing a DXF file.  By that I mean, I figured out how to enable the dxf import tool, and imported the file I had, but that's about it.  I'm struggling how to manage the workspace and actually view the file I've imported or do anything with it. Maybe I'm doing the import process wrong? Do I import it as a new scene, do I center geometry, etc, etc?  When I selected center geometry I could at least see something, but it looked like my imported file is maybe way to big for the workspace, as all I could see when I zoomed right out, was the first letter or so of some text from the imported file. (see screen shot).    Ok, I went the other way as you pointed out. Used 0.01, which brought a lot more into view, but still very large, so... used 0.001 which brought more into view, but it doesn't look anything like the plans I see in Autodesk?    To give you an idea of what it should be looking like, this is it in autocad. View from each side, floor plan for ground and 1st floor... two view of the entire building plot, one showing topography and a street view elevation.    Two more Blender screen grabs: this is imported at 0.0001. The first image is relatively close up to the workspace grid, and then second is zoomed out. The closer view looks like I'm getting close to the size I need. In the zoomed out view... I've no idea what is forming the large circular patterns as I can't see anything like that in the original drawings???  Would it help my progress if I removed some of the layers from the original file? I obviously don't need things like drains and internal wood framing, water mains, wiring, etc.     As you can see from the last screen grab... I've kinda got the plans into the work area, but I don't know what is affecting the view. What is causing this grey shading across the work area?  There was more of it, in ever increasing circles going out from the center, but I removed some by hiding certain layers, but can't seem to view just the plans without this shading?


Difference between “combination of ” and “combination between”

I have read both two uses:   The combinations of a, b and c, taken two at a time, are ab, bc, ac. We can not help but noticing a harmonious combination between classic and contemporary.   Are both uses interchangeable? Perhaps substitute combinations among for combinations of in the first sentence? Any idea is appreciated.


I want to change the colors that appear in the dropdown here:     If I open the Colors window and select another color, nothing changes. The steps outlined for older versions of Keynote don't work.  Thanks!


I've read tons of threads like this one, but I haven't come to a solution yet. I have a PC that I bought back in 2012, which has been having issues over the last few years. Lately I've just resorted to using my laptop instead. At any one point it just freezes and I have to hard-restart it. Usually I run Windows 10 on it, but today I tried Ubuntu, which also froze after a few minutes after just exploring the UI.  Details on the hardware:   Is there any hope for my computer, or should I just scrap it and buy another? Thanks, /Nils


How do I select all but two types of entities in Minecraft with the type selector?

I've asked this question towards a developer for Minecraft and I thought I'd ask here too since they might not see the question.  How do I select all but two types of entities in Minecraft?  For example, something like: /say @e[type=![Player,Item],r=50] (to clarify I also tried type=Item,Player, type=Item,type=Player etc)  Should select any entity that does not match players or items, so things like Creepers, Ghasts, XPOrbs, PrimedTNT and so on within a radius of 50 blocks and print them to the chat.  Instead it ignores one of the flags, and works with the other instead.


How do I protect myself if a scammer has my name, email, state and birthdate?

I gave a scammer my first and last name, gmail and birthdate. How can I protect myself from credit card and loan theft?


I have a scene set up with some objects with really nice shaders I mixed up in the Node Editor, and they look really good. However, I am trying to create a light blooming effect on the emission effect applied to one of my shaders. I have ramped up the strength of the emission effect, but while it makes it brighter, it doesn't give it the 'aura' look that I am seeking. Any advice on how to create the effect I am looking for?


Prove that $\sqrt{x_1}+\sqrt{x_2}+\cdots+\sqrt{x_n} \geq (n-1) \left (\frac{1}{\sqrt{x_1}}+\frac{1}{\sqrt{x_2}}+\cdots+\frac{1}{\sqrt{x_n}} \right )$

Let $x_1,x_2,\ldots,x_n > 0$ such that $\dfrac{1}{1+x_1}+\cdots+\dfrac{1}{1+x_n}=1$. Prove the following inequality. $$\sqrt{x_1}+\sqrt{x_2}+\cdots+\sqrt{x_n} \geq (n-1) \left (\dfrac{1}{\sqrt{x_1}}+\dfrac{1}{\sqrt{x_2}}+\cdots+\dfrac{1}{\sqrt{x_n}} \right ).$$  This is Exercice 1.48 in the book "Inequalities-A mathematical Olympiad approach". Attempt I tried using HM-GM and I got $\left ( \dfrac{1}{x_1x_2\cdots x_n}\right)^{\frac{1}{2n}} \geq \dfrac{n}{\dfrac{1}{\sqrt{x_1}}+\dfrac{1}{\sqrt{x_2}}+\cdots+\dfrac{1}{\sqrt{x_n}}} \implies \dfrac{1}{\sqrt{x_1}}+\dfrac{1}{\sqrt{x_1}}+\cdots+\dfrac{1}{\sqrt{x_n}} \geq n(x_1x_2 \cdots x_n)^{\frac{1}{2n}}$. But I get stuck here and don't know if this even helps.


I'm doing a highschool project and I wanted to know how to delete showing text in the terminal. I don't know how I can show text, delete it and write some text above while the script is running, without any interaction of the user. Obviusly I want this on a shell script and run it later. Sorry if my English is so bad.


Removing Installation Done outside the Package Manager

It's been a while since I started using (ubuntu) linux as my desktop, and I have a question about uninstalling software outside the scope of the package manager.  Most linux or unix distribution comes with a package manager and its repository, but not all software can I find in the repository. For example, I cannot install vmware linux virsion with apt, yum, emerge, or whatsoever; it comes with a shellscript installer.  In such cases, in order to uninstall, is the only way possible simply tracking the whole installation script and undo whatever was done? I believe there must be some more sensible way, but I couldn't find any.


Are there tips and tricks to overcome a fear of flying?

Are there tips and tricks for people with fear of flying that can makes them have a more pleasant experience when flying? I know drugs can do magic, and . I'm ideally after official advice and recommendations, but other tips and tricks would be nice as well.


Why would someone not use Foreign Keys in a MySQL database?

I'm confused about something, time and again i've seen developers including team leaders tell me that using foreign key constraints on their DB is bad practice, that it adds "logic to the database" but that goes against everything i've ever learned about SQL so far...   I need someone to tell me if i'm wrong for thinking that foreign key constraints are a major benefit or if i'm totally wrong and if so why. It just makes sense to me that in order to ensure data integrity you'd refuse any data that doesn't make sense being there, i'm sorry if this is a duplicate question, but i'm not really finding any definitive answers i'm happy with.


How do I install wine on a 64 bit install of Ubuntu 20.04.1?

Most things I try(following mostly outdated tutorials online) come up with missing dependencies. Can someone please walk me through installing everything required?


Can I downgrade from iOS 11 developer beta? I'm not worried about data preservation

I simply want to get rid of this buggy beta.  I regretfully installed the beta on my dailydrive/main device.  I'm aware that I may not be able to preserve all of my data because I didn't make any backups whatsoever, therefore I've performed manual backups of my most precious files.  I just want to go from iOS 11 Beta 2 to a clean and completely-reset latest-version of iOS 10.  I have the developer beta if that makes a difference.


What's the best way to protect your house from Endermen stealing your walls?

Since Endermen are capable of picking up blocks, they can pick up your blocks from your house.   What's the best way to prevent Endermen from stealing your blocks?


Find integers $t,z$ satisfying $(a+b)z+abt=1$

Let be $a,b,u,v$ integers and $au+bv=1$. I have to find integers $t,z$ satisfying $(a+b)z+abt=1$.  I think I can solve it by congruence. What do you think?  I realised $$bz\equiv 1 \quad (\text{mod}\, a)\Longrightarrow z\equiv v \quad (\text{mod}\, a)$$  $$az\equiv 1 \quad (\text{mod}\, b)\Longrightarrow z\equiv u \quad (\text{mod}\, b)$$  Any ideas? Thank you.


Return JSON from C# and deserialize it back in JS

Let's say we have this C# method:  [WebMethod] [ScriptMethod(ResponseFormat = ResponseFormat.Json)] public string GetEventsJson() {   Event[] events = new Event[] {   new Event   {     Ref = 1,     Name = "Some Name",     Date = new DateTime(2017, 3, 20, 12, 0, 0),     Description = "Some Description",     Localization = "Localization"   }   };   return Newtonsoft.Json.JsonConvert.SerializeObject(events); }   And we call this web service method via CORS request. It returns string like that:  <?xml version="1.0" encoding="utf-8"?> <string xmlns="http://tempuri.org/">[{"Ref":1,"Name":"Some Name","Date":"2017-03-20T12:00:00","Description":"Some Description","Localization":"Localization"}]</string>   Now, i'm trying to deserialize this back in JavaScript, I was trying to simple:  var data = jQuery.parseJSON(JSON.stringify(json));   or   var data = jQuery.parseJSON(json);   But it only returns error with second method:  Uncaught SyntaxError: Unexpected token < in JSON at position 0   Or does nothing with first method (I cant get for example data.Description because it says it's undefined)  So the question is: what is proper way to deserialize JSON returned by C# webservice?


I have the following patterns: "[list of tickets] [] : List of tickets" Example 1 How can I parse the above strings to validate the pattern below. [Jira-Ticket-list] [TAG] : <Some notes>" Also how can I parse the tickets and tag out of the string above? Expected output: Example 1: Tickets = [list of tickets] Tag = [TAG-0.3.4]


I constantly have error message "Low disk space". According to my storage I have "C" drive 464 Gb.  So I ran TreeSize to get the details of what taking space and it seems like all my stuff occupies 127 GB. What takes the rest of 337 GB? How can I fix it?


This is my first time working Biblatex, and bibliographies in Latex in general. I am writing a Math paper and would like to use the IEEE style. However, I am having a problem where there are empty brackets '()' in some citations. From what I've gathered, this problems seems to happen when the citation is referred to as @online. However, the sample.bib file was generated using Zotero and @online was chosen whenever a website was cited. I have shown a sample code with 2 citations where this problem occurs and one where it does not below. My hope is to be able to remove those brackets. For reference, I am using Overleaf as the editor. main.tex file: \documentclass{article} \usepackage[utf8]{inputenc}  \usepackage[ backend=biber, style=ieee ]{biblatex}  \addbibresource{sample.bib}  \begin{document}  Test one \cite{brit_time_nodate}  Test two \cite{lynn_primality_nodate}  Test three \cite{nitaj_mathematical_nodate}  \printbibliography  \end{document}  sample.bib file: @online{brit_time_nodate,     title = {Time Complexity (Exploration)},     url = {https://www.khanacademy.org/computer-programming/time-complexity-exploration/1466763719},     titleaddon = {Khan Academy},     author = {Brit, Cruise},     urldate = {2021-02-19},     langid = {english}, }  @online{lynn_primality_nodate,     title = {Primality Tests},     url = {https://crypto.stanford.edu/pbc/notes/numbertheory/millerrabin.html},     titleaddon = {Stanford University},     author = {Lynn, Ben},     urldate = {2021-02-20}, }  @misc{nitaj_mathematical_nodate,     title = {The Mathematical Cryptography of the {RSA} Cryptosystem},     url = {http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.357.6080&rep=rep1&type=pdf},     publisher = {Laboratoire De Mathématiques Nicolas Oresme},     author = {Nitaj, Abderrahmane},     langid = {english}, }   Output:  As a secondary question, what another citation style be suitable for a Mathematics paper? I would prefer to not use generic Latex styles but rather well-known standards (such as MLA, Chicago etc.) that is also suitable for Maths. Any help would be much appreciated!


I'm new to AJAX, jQuery, and JavaScript, so I'm sure I'm missing something simple here.  This is a hard problem for me to describe, but I'll do my best.   I have two html files, index.html and news.html.  I'm using AJAX to update a div that I have declared in the index.html file (its name is contentDiv).  I'm using the class attribute on several tags to pass information into my jQuery script.    When I click the link on the index.html page to load news.html into the contentDiv, it loads properly.  I then click a link to a .pdf file that is on the news.html file and nothing happens.  I'm trying to replace news.html with the .pdf requested.    I have the following in index.html         Here is an  tag in index.html that is working properly:  Terms and Conditions   Here is the news.html link that also works (this link is also located on index.html):  Current News/Announcements   The problem is when I click this link that is located in the news.html file, nothing happens:     I've tried this both with and without importing the same .js files that I do in the index.html file and both with and without the same document.ready script that is in index.html.  I would think that the . js imports and document.ready code would not be necessary in news.html because I'm using ajax to load news.html into index.html, but that's just a guess.   Does anyone have any ideas on where I'm going wrong?   Thanks


I have been trying to upload my picture in my US visa application but I keep getting this error: "Error: There was a missing or invalid parameter in the request" and I couldn't do anything beyond that.  Last night I was able to upload the photo but it didn't let me review and confirm it.  I'm worried as my US visa interview is tomorrow at 11:45AM.  What can I do now?


I am trying to create a 2D game in Java where a user is prompted for a row width and column length. A 'world' object is created that looks like this when printed (where P is the player's character):  P--- ---- ---- ----   The user can then enter up, down, left, right or exit which should move the P around and do nothing if the move would move the character off the map. My issue is after I enter the width and length, I get the following error:  java.lang.NullPointerException at World.displayWorld(Driver.java:90) at Driver.main(Driver.java:28)   I believe this means that Java is seeing worldDimensions.length as empty/null?? I thought I was assigning a value to it when the world object is created.. Any guidance is much appreciated!  Here's my code:   import java.util.Scanner;  public class Driver {     public static void main(String args[]) {          //Create a scanner object         Scanner input = new Scanner(System. in );          boolean exit = true;          //Prompt user to enter world width and height         System.out.print("World width: ");         int userWidth = input.nextInt();         System.out.print("World height: ");         int userHeight = input.nextInt();          //Create a world object         World world1 = new World(userWidth, userHeight);         world1.displayWorld();          System.out.println("Possible inputs: up, down, left, right, exit");          while (exit = true) {             //display world             world1.displayWorld();              System.out.print("ACTION > ");             String userAction = input.next();              if (userAction == "up" || userAction == "down" || userAction == "left" || userAction == "right" || userAction == "exit") {                 switch (userAction) {                     case "up":                         world1.moveUp();                         break;                     case "down":                         world1.moveDown();                         break;                     case "left":                         world1.moveLeft();                         break;                     case "right":                         world1.moveRight();                         break;                     case "exit":                         exit = false;                         break;                 }             } else {                 System.out.println("Invalid Input. Possible inputs are: up, down, left, right, or exit.");             }         }      } }  class World {     static private char[][] worldDimensions;     static private int characterRow;     static private int characterColumn;      public World(int userWidth, int userHeight) {         char[][] worldDimensions = new char[userHeight][userWidth];         int characterRow = 0;         int characterColumn = 0;          for (int row = 0; row < worldDimensions.length; row++) {             for (int column = 0; column < worldDimensions[row].length; column++) {                 if (characterRow == row && characterColumn == column) {                     worldDimensions[row][column] = (char)                     'P';                 } else {                     worldDimensions[row][column] = (char)                     '-';                 }             }         }     }      public void displayWorld() {         for (int row = 0; row < worldDimensions.length; row++) {             for (int column = 0; column < worldDimensions[row].length; column++) {                 System.out.print(worldDimensions[row][column]);             }             System.out.println();         }     }      public void moveUp() {         if (characterRow - 1 >= 0) {             characterRow--;         }     }      public void moveDown() {         if (characterRow + 1 <= worldDimensions[0].length) {             characterRow++;         }     }      public void moveLeft() {         if (characterColumn - 1 >= 0) {             characterColumn--;         }     }      public void moveRight() {         if (characterRow + 1 <= worldDimensions.length) {             characterRow++;         }     } }


$\|h(x)-h(y)\|\geq 3\|x-y\|$ prove that image of open is open

Let $h:\mathbb{R^2}\rightarrow \mathbb{R^2}$ be a surjective map such that   $\|h(x)-h(y)\|\geq 3\|x-y\|$ for all $ x,y\in \mathbb{R^2}$. Here $\|\cdot\|$ denotes euclidean norm on $\mathbb{R^2}$.  Prove that the image of every open set (in $\mathbb{R^2}$) under $h$ is an open set.  My try : Every open set in $\mathbb{R^2}$ can be written as union of balls $B_r(a)$ of radius $r$ entered at $a$ and every ball $B_r(a)$ can be obtained by  scaling up and translating the center of the unit ball $B_1(0)$ in $\mathbb{R^2}$ .So it is enough to prove that $h(B_1(0))$ is open set . So i have to show that for any $(a,b)\in \mathbb{R^2}$ there exists an open ball $B_r(h(a,b)) $ such that $B_r(h(a,b)) \subset h(B_1(0))$ .  My problem is that i can't find an appropriate $r$ .   Please help from here. If the above  approach is completely wrong then provide a solution. Thank you


Find if set $I$ of all injective functions $\mathbb{N} \rightarrow \mathbb{N}$ is equinumerous to $\mathbb{R}$

I need to find if set $I$ of all injective functions $\mathbb{N} \rightarrow \mathbb{N}$ is equinumerous to $\mathbb{R}$. Still, I have no idea how to work with set of functions, it's something new to me since I have only encountered sets of numbers before.


I am having Refresh Token to generate Access Tokens in Salesforce and by using api calls I can successfully retrieve data using Postman... But my problem is I am automating one of the scenarios in Salesforce including login... So is there a way to login into Salesforce by using Access Token in Web Browser so that I can skip the verification step which is asking each time when I start my test Automation?  My instance is  and I need to proceed to this page after login


how do i replace a character in my array with another character?

i have a array - the output of my array looks like this:  Array (     ["US"] => 186     ["DE"] => 44     ["BR"] => 15     ["-"] => 7     ["FR"] => 3 )   and i want to replace the "-" with "other"  so it should look like this at the end:  Array (     ["US"] => 186     ["DE"] => 44     ["BR"] => 15     ["other"] => 7     ["FR"] => 3 )   could someone help me with this? str_replace havent worked with me... and if you could i want to have the "other" part of the array at the bottom -  like this:  Array (     ["US"] => 186     ["DE"] => 44     ["BR"] => 15     ["FR"] => 3     ["other"] => 7 )   thanks :)  current code:   $array_land = explode("\n", $land_exec_result);  $count_land = array_count_values($array_land);         arsort($count_land);         $arr['other'] = $count_land["-"];         unset($count_land["-"]);   but this havent worked for me :/


When searching with a tag, tag info displays twice

When searching with a tag, for example , the C++ tag information displays twice:    This is reproducible for me on both Chrome and Edge, but only on Stack Overflow, not on beta sites or Meta SE.


Locating the first item in a list of lists

I have this scenario:  >>> y=[[1]] >>> y=y*2 >>> y [[1], [1]] >>> y[0].append(2) >>> y [[1, 2], [1, 2]]   What I'd like to do is add the 2 into the first list within the outer list i.e. this is the desired output:  [[1, 2], [1]]


How can one find out your progress towards the Curious, Inquisitive & Socratic badges?

These badges were only recently added to StackExchange. I would like to know if there is any way I can find out how many more questions I should ask to get these badges.   For e.g. like the counters for the review-related badges:


So I am trying to install and update some packages and for that I need some space (around 1 GB) in my root because every-time I open my Ubuntu I get a message that there is not enough space in your root. My gparted looks like this:  I am having a hard time understanding how can I increase my root space as I have much unallocated space in my drives. I have already tried resizing2fs my /dev/sda5 but nothing worked. I got an output saying that "The filesystem is already 9301770 blocks long. Nothing to do". What else can I do or how should I proceed ?


I have a full component of eggs at the moment. Mostly 2k with a couple of 5k (and a 10k incubating )  Other than buying a load of incubators and walking loads. Is there a way to get rid of the more common eggs to give me a chance to pick up others.  There doesn't seem to be an equivalent to transfer for the eggs.


How to see download count of an Android app on Google Play store?

I cannot see the download counts of one app on Google Play.   How can we know that number of one app?


How to Change Element in 2d list in this case

In this , I want to change first element of second nested list but.  L1=list('|  |') L2=[L1,L1] print L2  >>>[ [ '|', ' ', ' ', '|' ], [ '|', ' ', ' ', '|' ] ]  L2[1][0]='@' print L2  >>>[ [ '@', ' ', ' ', '|' ], [ '@', ' ', ' ', '|' ] ]   Its Change both nested list!! Where I am going Wrong??


Google Earth multiselect points to delete or drag & drop

How can i select multiple items in Google's Earth sidebar "places" menu to delete or to move to a folder?


Question appears multiple times in a search result with Q : and A :

The Stack Overflow search shows questions twice. See  for example.  Results include "A: Add Search Engine into MVC Music Store" and "Q: Add Search Engine into MVC Music Store".  Why is search displaying the question twice, and what does "Q" and "A" mean?  Edit:   @Stephen answer :  The search is returning both a question (Q) and an answer (A) to the question, as both posts match your search criteria.  and my another question  If the question have multiple (like 100) answer ,then the answer link(A: Question Link) shown 100 times?  Is it correct functionality ? But i saw only one answer link , not a other answer link .. why ?


Makeglossaries - cannot compile glossary list

I am trying to get the glossaries package to work. I have created a minimal .tex file to test it.   I am using TeXworks. My .tex file currently looks like this:  \documentclass{amsart} \usepackage{amsmath, amssymb,amscd}  \usepackage{glossaries}  \newglossaryentry{test}{     name=Test,     description={is a test} }  \makeglossaries  \begin{document}  This is a \gls{test}.  \printglossaries  \end{document}   The compiled pdf has the sentence "This is a Test", but there is no glossary list. I am currently compiling under the option "pdfLaTeX+MakeIndex+BibTeX".   I have tried compiling just under MakeIndex by itself and then compiling the pdf again, but there is still no list.  I have tried adding a "makeglossaries" option to the list of compiling options according to the following directions I found:     "You go to TeXWorks > Preferences > Typesetting, and add a processing tool. Name it "makeglossaries" (or whatever you'd like, really), enter the program "makeglossaries" (which should be already installed somewhere---don't worry about the full pathname), and add a single argument: "$basename" so that your main filename will be passed to the makeglossaries process."   But when I compile under the new "makeglossaries" option I get the following error:     makeglossaries.exe: The Perl interpreter could not be found.   After searching for info on this error I downloaded ActivePerl, following the link from this Stack Exchange question: . But I still get the error when compiling under the "makeglossaries" option.  Can anyone help me figure out how to get the glossary list to appear in the compiled pdf?


I am currently in high school and we are studying radicals. I had asked my math teacher why $\sqrt{ab}=\sqrt{a}\sqrt{b}$ (for all a,b>0) and he tries to prove it by arguing that $a^{1/2}*b^{1/2}=(ab)^{1/2}$ (an exponent law). However, I find this proof problematic since $x^{1/2}$ is simply defined as $\sqrt{x}$, so the reasoning is circular.   My view is that $\sqrt{ab}=\sqrt{a}\sqrt{b}$ because once we square both sides we get $ab=ab$. Since we're obviously referring to the positive root, and the function $f(x) = \sqrt{x}$ is injective, it necessarily follows that the original expressions $\sqrt{ab}$ and $\sqrt{a}\sqrt{b}$ are equivalent because for injective functions it is not possible to map distinct elements in the domain to the same element in the range ($ab$). Hence they are equivalent expressions.   My question therefore is, is my proof valid and/or rigorous (I find it convincing but maybe it's wrong; I just want to be clear) and secondly was my teacher's proof correct?


how do i create a slideshow in GIMP for a wallpaper

how do i create a slideshow in GIMP image editor using jpeg images saved in a folder and use it as wallpaper in Ubuntu 12.04 LTS version? The slideshow has to be timed so that the wallpaper keeps changing at fixed time interval, and background music is also present..


Where to ask questions about programming languages themselves?

Note that this question is much more specific than , and the accepted answer there does not answer my question clearly (but it seems to suggest StackOverflow as the answer).  Here are a few examples of questions about programming languages themselves, not about their application or particular implementation:         The question I have in mind for asking would be: "Scheme's facilities for building expressions with interpolation (quasiquoting) seem incomplete, what are the alternatives?".  For asking questions about programming languages, the only alternatives among the Stack Exchange sites that I can currently (2017) think of are:   , , and .   I believe that for quite some time already Stack Overflow is reserved for practical issues.  Once I posted there a  about Scheme, and it got migrated to Programmers/SoftwareEngineering.  I used to ask questions about programming languages on Programmers.SE, but that site was converted into Software Engineering and its scope changed.  Now it is reserved for questions about   software development methods and practices requirements, architecture, and design quality assurance and testing configuration management, build, release, and deployment   Programming language syntax and semantics do not fit into any of these categories.  There is left the site about Computing Science, which seems to be a good fit as questions about   programming language semantics, formal methods   are allowed, but I noticed that they do not even have tags for individual programming languages.  I am a bit lost.


What does the register keyword do in C language?  I have read that it is used for optimizing but is not clearly defined in any standard.  Is it still relevant and if so, when would you use it?


So when you're looking for questions, you can filter questions based on a certain tag, by simply writing that tag in the search.  However, can you do the exact opposite of that, i.e, certain tags filtered out? That would be very helpful for me, as I have to scroll pages after pages of the same tag before I can find an answerable question.  Remember, this is different from looking up a certain tag. I can answer questions with every tag but a certain one.


Proving the existence of a sequence of functions converging to 0 with an added property

This is a problem from Rudin's Functional Analysis:  Show that there is a sequence of functions $\{ f_n \}$ in $X$ (the vector space of all complex functions) such that $f_n \to 0$ pointwise, but if any sequence $\{ \gamma_n \}$ tends to $\infty$, $\gamma_n f_n \not\to 0$.  The hint says to use the fact that the collections of all complex sequences converging to $0$ has the same cardinality as $[0,1]$. Honestly, this confused me more than it helped me.  My main issue is through the method of showing existence: I am not sure if I should attempt to construct an explicit sequence $f_n$, or if I need to appeal to other nonconstructive means such as Zorn's Lemma, etc. I have been trying to construct clever choices of sequences for a good bit now, but it always seems like I will be able to find a sequence that diverges slowly enough to allow that $\gamma_n f_n \to 0$.   Thanks!


Counterexample for "the Lie algebra is commutative iff the Lie group is commutative"

If $G$ is a connected Lie group, and $\mathfrak g$ is its Lie algebra, then $G$ is commutative iff $\mathfrak g$ is commutative. But when we remove the "connected" condition, could you provide a counterexample? Further, without the "connected" condition, is one direction always right?  Thank you!


Prove that $$a^2(1+b^4)+b^2(1+a^4)≤(1+a^4)(1+b^4).$$  This is a problem from the pre College mathematics. Please help. This inequality has to be proved for all reals $a$ and $b$


What do two question marks together mean in C#?

Ran across this line of code:  FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();   What do the two question marks mean, is it some kind of ternary operator? It's hard to look up in Google.


I know this question may have been asked before but i really need some advise according to my needs. Have finalized upon Nikon d5300 but not able to decide upon the lenses. Should i go for 18-55+55-200 or just 18-140? I need zoom because i will travel (not much) and would like to do macro photography or portraits. But not sure of the comfortability level while changing the lenses. Please help!


I can't find a program I wanted from the software centre, so had to download a tar file, but it wont install. Do I have to have a degree in physics or coding just to get it to install? I can't understand why a mouse click wont start the install process? I've tried to figure out the 'compile' etc commands, but I can't do it. Thanks


Alternating sum of binomial coefficients: given $n \in \mathbb N$, prove $\sum^n_{k=0}(-1)^k {n \choose k} = 0$

Let $n$ be a positive integer. Prove that   \begin{align} \sum_{k=0}^n \left(-1\right)^k \binom{n}{k} = 0 . \end{align}   I tried to solve it using induction, but that got me nowhere. I think the easiest way to prove it is to think of a finite set of $n$ elements, but I can't find the solution.


I am about to buy clothes to cosplay Pansy Parkinson- but... what were clothes like in the wizarding world? Parkinson is a blood supremacist so she wouldn't wear muggle clothes, and since so many wizards are pureblood, what do they wear? is it linked to a specific time?


Sorting an arraylist into map using iteration

I am making a small programme, part of which iterates over an arraylist sorting the different competitors into a map depending on abilty of each competitor in the array list. It seems to work apart from one problem. The first if statement is not working. Any competitor classed as beginer is not sorted into beginerResults, but instead standardResults. The others are working fine however. Any suggestions?    public void sort()   {     for (Golfer rating : competitors)     {        if (competitors.getScore()== "beginer")       {         beginerResults.put(competitor.getName());         }       if (competitors.getScore()== "Intermediate")       {         intermediateResults.put(competitor.getName());         }       else       {         expertResults.put(age.getName());       }     }   }


I'm trying to put equation numbers next to text as if said text was an equation. If I use \text{} in an align* environment, it typesets the text right-aligned and the whole environment centered, but that's not what I want. I would like the text to look like in an itemize or enumerate environment (for example, indented), but still with an equation number behind it. And that equation number should come from the regular equation number "pool".  Ideally, it would look like this:  We have to make sure that:   A is very b,             (1)   A is not c.              (2)   How can I write this in LaTeX?


Why catch Exceptions in Java, when you can catch Throwables?

We recently had a problem with a Java server application where the application was throwing Errors which were not caught because Error is a separate subclass of Throwable and we were only catching Exceptions.  We solved the immediate problem by catching Throwables rather than Exceptions, but this got me thinking as to why you would ever want to catch Exceptions, rather than Throwables, because you would then miss the Errors.  So, why would you want to catch Exceptions, when you can catch Throwables?


Surface reflectance product - do I always need it?

There is a neat Surface Reflectance product of Landsat imagery. I know the difference between SR and raw products: SR presents calculated values, that are supposed to represent state of the Earth surface, while "normal" products are disturbed by all kinds of scattering on the way from the Sun to the surface and back to the sensor.  Now, I'm performing a land classification of terrain to extract boundaries between two types of land use. I have many images and this is unsupervised classification. Do I really need SR product here? Would I need it, if it was supervised classification? I suppose it's no in both cases, as I don't directly compare any values between images. I just need to know exact position of this boundary.


Why does the Lorentz transformation have to be a linear transformation?

In my textbook, they say the following statements before doing a proof for the Lorentz transformation:     We know that the Galilean transformation $x' =  x - vt$ is incorrect, but what is   the correct transformation? We require a linear transformation so that each   event in system $K$ corresponds to one, and only one, event in system $K$.   Why must it be a linear transformation? Wouldn't any one-to-one function work?


AES encrypted data length using WebCrypto

What I'm trying to do is encrypt 16 byte packets of data using the 128 bit AES-CBC encryption provided by SubtleCrypto.encrypt() in a web browser.  What I expected to find was 16 bytes of encrypted data for 16 bytes of input.  What I actually find is 32 bytes of encrypted data for 16 bytes of input.  Specifically, 15 bytes of input produces 16 bytes of output, 16 bytes of input produces 32 bytes of output, and 17 bytes of data produces 32 bytes of output.  My question is, why does 16 bytes of input data produce 32 bytes of output?  I would have suspected that this might happen only with > 16 bytes of input data, not >= 16 bytes.  Save the following test code to a file and open with a web browser.     <title>WebCrypto encrypt test</title>
See console log.


Best way to burn data to dvd using command line

I have three kinds of file:  Iso file, Directory, Txt file,  ISO: debian7.iso Directory: Archives from /var/cache/apt/archives File: README   I want to burn them into a DVD using command line...  NOTE:  I don't want my iso file be extracted  What I tried is:  sudo wodim  dev=/dev/dvdrw -v -data /path/to/debian7-64bits/   But is gives me errors  What is the best way to do that?  Thanks


Where can I get the source code for stackoverflow.com's WMD version?

I think the question is self-explanatory - its not that that I want SO source code.  What I am looking for is how they added image upload from PC feature. I need to implement it too.


For any polynomial $p(x) = a_0 + a_1x + · · · + a^kx^k$ and any square matrix A, $p(A)$ is defined as $p(A) = a_0I + a_1A + · · · + a_kA^k$. Show that if v is any eigenvector of A and $χ_A(x)$ is the characteristic polynomial of A, then $χ_A(A)v = 0$, Deduce that if A is diagonalizable then $χ_A(A)$ is the zero matrix.  I got that $p(\lambda)$ is the eigenvalue of $p(A)$ and if A is diagonalizable then $χ_A(x)$ is the zero matrix since p(A) is similar to its diagonal matrix p(D)  $$p(D) = a_nD_n + · · · + a_1D + a_0I$$  =  $\begin{matrix} p(\lambda_1) &0&...&0\\0& p(\lambda_2)&...& 0 \\ ...&...&...&...\\0&0&... & p(\lambda_n) \end{matrix}$


Negative Effects on UX from Text on Images

Jakob Nielsen in "Eyetracking Web Usability," recommends against placing text on top of images or textured background in advertisements because only 35% of people will look at it.  Is there any other research addressing how text on images or patterned background affects the usability or readability of that text or site?


What forms of identification can I use if I don't have a credit / debit card on the Deutsche Bahn if passports aren't allowed?

I will be traveling on my own to Germany in a few days, and will take the train on Deutsche Bahn.   I am 17, and have no credit cards, debit cards, etc. My parents will be booking the journey in advance with their credit card. I just have no idea what valid ID I could use that falls under the requirements, especially if passports aren’t allowed.


How big of a neutron star would be needed to form a quark star inside of it?

A quark star is a hypothetical type of compact exotic star composed of quark matter. These are ultra-dense phases of degenerate matter theorized to form inside particularly massive[citation needed] neutron stars. -Wikipedia   If you add enough mass to a neutron star it forms a black hole but how much mass is needed to form a quark star? When do neutrons and protons start to break down into a mush of quarks and gluons?


Can anyone tell me what I'm doing wrong? I have a database with a table called henry_author that looks like this:  Table Name: henry_author | author_num | author | ----------------------- | 0          | james  | | 1          | jack   |   I'm trying to get both the numbers from the henry_author table.  Here is what I'm doing:  public static void main(String[] args) throws Exception {     Connection conn = null;     PreparedStatement pstmt = null;     Statement stmt = null;      try {         conn = getConnection(); // this is basically the DB_URL, USER, PASS and DriverManager.getConnection() method/function I made         String query = "SELECT author_num FROM henry_author";         ResultSet rs = stmt.executeQuery(query);          while (rs.next()) {             int number = rs.getInt("author_num");             System.out.println("Author num: + number);         }      } catch (SQLException sqle) {          sqle.printStackTrace();      }  }   I keep getting the error: java.lang.NullPointerException. No clue on what is wrong with the code.


I tried to install steam on Linux but it says “you are missing the following 32 bit libraries,and steam may not run: libic.so.6


Why do "Community Wiki" Q & A not get awarded reputation?

I stumbled across a  on SO while looking for answers and ended up adding my own  to the list of suggested solutions. Soon after this I realized that this question was a community wiki before I had added my answer to it.  According to the community this was the best answer as it received most upvotes for the question but I received nothing for it. Why?  Questions:   Why does making a question/answer a part of the community wiki mean no one can earn points for contributing to it?  What's the reason for the reputation being disassociated with the contributor?   I understand on a technical level that the posts sort of gets owned by the community user instead of me but that shouldn't mean I get nothing for contributing should it?  Edit:   I've read the post  and I'm not concerned with what Community Wiki posts are. I'm concerned with the rep-denial aspect and the reasoning behind it.   That said Robert's answer addressed this.


How to switch data display in UI of 2.7 back to 2.6 style?

is there a way to make 2.7x version of blender to display numbers-data in fields like x/y/z etc. like in 2.6x version of blender?  Make all data appeal at center, not like in 2.7 new style, when for example in location tabs “x” is always at the left and numeric value is at the right? Thank you.


If $\gcd(a,1729) \neq 1$, show that $a^{37 }\equiv a \pmod {1729}$

The question is for any integer $a$, show that $a^{37} \equiv a \pmod{1729}$.  I have already proven using fermat's little theorem that if $a$ and $1729$ are relatively prime, then it is true, but I do not know how to do it if they are not. Please help.


Change time after which locked computer turns off display

I have (I think) a standard sleep / turn off display settings in my Windows 10:    Yet my computer turns off display after 30 seconds since locking the computer.  If I lock computer manually, display's power is cut-off (display is turned off) after just 30 seconds since lock / stop of work. If I stop the work, but do not lock the computer then Windows locks it up after two minutes and then turns off the display after another 30 seconds.  To summarize: My display is never turned of after 15 minutes, despite above settings, it lasts turned on for between 30 seconds and 150 seconds at most.  How can I control when my display for locked computer is turned off, or how can I enforce that my display will always be turned of -- as set / said -- after 15 minutes and not even a second earlier?  Edit: I went through all advanced power settings etc., all for nothing -- everything I look or check, I can clearly see the same setting -- 15 minutes. I must be looking in an incorrect place, though.


Book about a pair of siblings that had powers, the younger brother had powers to control people but concealed it the whole time?

I think the book had dragon in the title not too sure. The older sister I think had ability to control fire I think. They somehow ended up in a castle. I can't remember much of it.


Limit of sequence $x_n=\frac{1^p+2^p+...+n^p}{n^{p+1}}$

The limit the following sequence is $\frac{1}{p+1}$. I have tried to prove it, but I don't success. Could you help me?  $$x_n=\frac{1^p+2^p+...+n^p}{n^{p+1}}$$  $$p\in\mathbb{N}$$  Thanks in advance!


Problem with assigning delegates in for-loop

I have an application that is capable of plugins (MEF). The plugins are WPF UserControls that import services.  The user can select the wanted plugin from the main menu of the application.  To do this, i use the following loop:  foreach(IToolPlugin Plugin in ToolPlugins) {     Plugin.Init();     MenuItem PluginMenuItem = Plugin.MenuItem; //New MenuItem but with Header set.     PluginMenuItem.Click += new RoutedEventHandler(delegate(object o, RoutedEventArgs e) { DoSomething(Plugin.Control);});     PluginsMenu.Items.add(PluginMenuItem); }   That works very fine for a single item. But as soon as i have more than 1 plugin, all menuitems execute the delegate of the last loop. Or at least with the Plugin.Control of the last loop.  How can i fix this? Thanks for any help.


Given $x,y\neq 0$ such that $x^2+xy+y^2=0$. Evaluate the following, $$\left(\frac{x}{x+y}\right)^{2013}+\left(\frac{y}{x+y}\right)^{2013}$$   I have tried to merge the fraction, factorize the numerator and simplify the fraction, but I don't know when to use the initial equation. Any ideas or solution would be helpful.


The piece under key hinge –– that looks like a nipple –– came loose. What to do?

The left arrow key on my 2014 model Mac Air has been acting weird, so I took off the key cap and hinge to see what was going on and I discovered that the tiny piece that looks like a nipple (or a suction cup, if you will) is not attached to anything. I took off another small key to see how it should be. The nipples under other keys are firmly attached to either side of the key hole, but this one is kinda loose.   As a result, the key works but you have to push really hard on it.  How can I fix this? Can I just superglue it in place or do I need to get a new nipple-thingy?  thanks.


AES encryption time difference for same data

When encrypting same data with AES, encryption time for the first encryption is longer than the second one.  In the same program, I have written encrypt() function twice and measure elapsed time. I don't know why?


I accidentally executed      sudo chmod -R 777 /   I was actually trying to change a specific folder permission recursively, btw i did stop the command before it changed everything.  But now, i can't execute for example      sudo   Every time i try to sudo something it throws me this error:     effective uid is not 0, is sudo installed setuid root?   Btw i know i can use chown -R root:root /usr/bin where sudo is located, but of course i don't have the permissions to do this.  So, how can i revert this process? Or at least save the sudo file without reinstalling everything?  The system is still connected to the internet and seems to work fine besides the sudo issue.  Thanks in advance.


How do I abort the execution of a Python script?

I have a simple Python script that I want to stop executing if a condition is met.  For example:  done = True if done:     # quit/stop/exit else:     # do other stuff   Essentially, I am looking for something that behaves equivalently to the 'return' keyword in the body of a function which allows the flow of the code to exit the function and not execute the remaining code.


Guidance for new users who are responding to comments

There is a pattern that I frequently see with new users: the user posts a question, someone leaves a comment requesting clarification, and the user posts the clarification in a comment.  I anticipate this is likely because new users might not be familiar with our mission of building up an archive of high-quality questions that will be useful to others, and so it doesn't occur to them that we'd prefer them to respond by revising their question to improve it. I think we could help users by providing guidance in this situation.  In particular, I am imagining that a brief message could be shown, under the following conditions:  A user ("the asker") posts a question The asker has reputation below some threshold (say, below 30) There is a comment under their question from someone else The asker has not posted a comment under this question yet The asker moves the focus into the comment field  Then perhaps we could have a message that provides guidance on when to comment vs when to edit their question.  For example: "Edit your question if you are adding more details." (though this probably needs revising and improvement) I am thinking this might help teach newcomers about how to use the site, and in a way that is fairly unobtrusive for experienced folks.  I am also hoping it will lead to higher-quality questions, by avoiding a situation where there is critical information buried in the comments, and make life easier for experienced users, as they won't need to repeatedly guide new users on this.


Equivalent of ".gitignore" file with Subversion

I am being forced to work with Subversion on a current project.  Someone has unkindly added the bin and obj folders to the repository.  Other than removing them, and committing the removal, is there an equivalent of .gitignore file I can add to the repository to make the guilty party in the development team never add them again?  I know I can alter my own global ignore pattern, but ideally I'd like the whole development team to be able to share this on a project level.


Cardinality of a set that contains a transitive relation.

I want to compute the cardinality of the following set: $$A= \{ R\subset \mathbb{N}\times\mathbb{N} : R \text { is  a transitive relation}\}$$  I understand that the cardinality is bounded above by $|P(\mathbb{N}\times \mathbb{N})| = 2^{\aleph_0}= \aleph$, but how to find a lower bound?


Is a resistor needed for LEDs in this beatbox project?

I'm making a LED beatbox (). I'm using 8 LEDs (5 millimeters, I don't know if this helps) and my power source is 12 VDC 800 mA. Do I need to add a resistor? If yes, which one should I use?


Value of Series $\sum_{n=1}^{\infty} \frac{1}{1-x^n}$

i have encountered the following series on a Physics problem: \begin{equation} S = \sum_{n=1}^{\infty} \frac{1}{1-x^n} \end{equation}  I would like to know if there is any specific Function assigned to this series. Thanks for you attention.


Colon or comma: there are plenty of options [: , ] from X to Y

Is a comma or a colon the correct punctuation of the following sentence?     There are plenty of meals from which to choose /// from pasta to steak.   At the break between clauses, denoted by /// it seems a colon is warranted as what comes before is a complete sentence, and what follows is explanatory details and not a complete sentence.   But a comma also makes sense, as it turns the last portion of the sentence into a modifier. But the modifier from pasta to steak would not be modifying the thing that comes immediately before, so it seems to violate that rule.   I see a similar question here:  but that question's modifier clause does not contain the from x to y structure, and as such the answer to that question does not fully apply here. We would not replace the colon with words such as namely, that is, as, for example, for instance, because, as follows, because the word from would make that awkward: options namely from pasta to steak


Proving theorem connecting the inverse of a holomorphic function to a contour integral of the function.

I am asked to prove this theorem:  If $f:U \rightarrow C$ is holomorphic in $U$ and invertible, $P\in U$ and if $D(P,r)$ is a sufficently small disc about P, then   $$f^{-1}(w) = \frac{1}{2\pi i} \oint_{\partial D(P,r)}{\frac{sf'(s)}{f(s)-w}}ds$$     The book says to "imitate the proof of the argument principle" but I am not seeing the connection.


Retriving all Active picklist values of all recordtypes

Can you please guide me best way to retrieve all active picklist values of all recordtypes of object. Can it be possible through API or any Apex Script.  I want something like below and i will write them in my file:  Obect Name, RecordTypeName, PicklistValues   Thanks


I am trying to send automated email when ever some body register on my website. There is no exception whenever I register myself on website (Local server) . I also added using system.Net.Mail and web.Config script a. Following is my piece of ASP.NET code:   public void SendWelcomeMail()     {         string EmailTO = TextBoxEmail.Text;         string EmailFrom = "exampleEmail@gmail.com";         string Pass = TextBoxPassword.Text;         try         {             MailMessage message = new MailMessage();             message.From = new MailAddress(EmailFrom);              message.To.Add(new MailAddress(EmailTO));              message.Subject = "Welcome";             message.Body = "You are now registered with your email ID "+EmailTO;             message.Body = "Your Password is "+Pass;             SmtpClient client = new SmtpClient();             client.Send(message);         }         catch         {             Response.Write("Sorry there is an exception. Some thing must be wrong");         } }


Fibonacci Sequence In Python (Most Efficient)

Anyone know the most efficient way of displaying the first 100 numbers in the Fibonacci Sequence in Python please?  Here is my current code:  fib1,fib2,fib3= 0,0,1    while fib3< 100:      print(fib3)      fib1=fib2      fib2=fib3     fib3=fib1 + fib2


The terminal does not display Devanagri scripts (Hindi, Nepali, etc.) properly

The terminal is not combing Unicode characters correctly. How do I solve this?


I would like to inject some elements directly after the <body> tag.   Is that possible using only WordPress hooks?


Are the effects of general relativity accounted for in the calculation of the trajectory of the PARKER probe?

I think about the precession of the perihelion of the trajectory as the probe comes closer to the sun than Mercury, which was the first successful test for the general relativity.


Is SO using a vendor available API to show edit history of posts? I have a mongodb setup which implements versioning of documents and I would like to emulate something similar to this:


How to stretch the figure environment across textheight?

When I use the figure environment to set an image as a float in a separate page ([p] specifier), I want to be able to use up the full text height, so that the image and its caption are precisely alligned with text on the adjacent page. I want to have captions at the bottom. This means I need to set the image height to \textheight MINUS the height of the caption that comes after.  I am aware of question:  and the solution offered there works in continuous text, but not in the figure environment.  I was also made aware of question , which comes very close to what I need, except I think that having to set the number of lines in a caption manually is a little awkward, and I am looking for a completely automatic way of computing the caption height.


System.out.print ("Create a savings account? Enter yes or no: "); String createSavingsAccount = console.readLine(); if (createSavingsAccount == "yes") {     System.out.print ("Enter the balance in the savings account: ");     savingsBalance = Double.parseDouble(console.readLine()); }    When I enter yes, the program skips the if statement and goes back to the main menu. How do I get it to check the user input?


What does "All round him the long scar smashed into the jungle was a bath of heat" mean?

I don't understand this sentence:     All round him the long scar smashed into the jungle was a bath of heat.    What does it mean? Can a scar be a bath of heat?


Finding the maximum value of $\int_0^1 f^3(x)dx$

Find the maximum value of $\int_0^1 f^3(x)dx$ given that $-1 \le f(x) \le 1$ and $\int_0^1 f(x)dx = 0$   I could not find a way to solve this problem. I tried to use the cauchy-schwarz inequality but could not proceed further  $$\int_0^1 f(x) \cdot f^2(x) dx \le \sqrt{\left(\int_0^1f^4(x)dx\right) \left( \int_0^1 f^2(x) dx\right)}$$  Any hints/solutions are appreciated.


Prevent apt-get update from getting i386 packages?

I'm on 64-bit Lubuntu 14.04 LTS. I keep the system fully updated by running apt-get update and apt-get dist-upgrade twice daily.  However, I notice that apt-get update "gets" both i386 and amd64 packages for nearly everything. For example:  Get:47 http://archive.ubuntu.com trusty/universe amd64 Packages [5,859 kB]   and  Get:51 http://archive.ubuntu.com trusty/universe i386 Packages [5,866 kB]   I've run dpkg -l | grep ":i386" but I just get back the prompt, indicating, I think, that I have no i386 packages installed.  My reason for asking is that if I could prevent the "getting" of i386 packages during apt-get update, I save my bandwidth and lessen the load, however marginally, on Canonical's servers.


Does anybody know a way to add a command to an item (emerald, stick, other ingredients), then when left or right clicked, it executes a command?


Why “Would you mind if I asked you something?” is correct?

Instead of "Would you mind if I ask you something?" Why past tense, I don't get it?


There are some proprietary apps that are being provided only in 64-bit version.


I have posted a similar question before. But the issue remains still. So it happens after I upload my system for galaxy S3 two week ago. And after that  whenever I connect to my laptop , it wouldn't pop up the option to let me select MTP as before. And  this is what  displayed in control panel-> Hardware and Sound ->Devices and Printers     Does anyone know a possible solution to this?


I'd like to find the SVD for the following matrix: $$\left(\begin{array}{cc} 5 & 5\\ -1 & 7 \end{array}\right)$$  I've calculated the eigenvalues and eigenvectors of $XX^{T}$ and the eigenvectors of $X^{T}X$, arriving at  $$X=\left(\begin{array}{cc} 5 & 5\\ -1 & 7 \end{array}\right)=U\Sigma V^{T}=\left(\begin{array}{cc} \frac{1}{\sqrt{2}} & \frac{1}{\sqrt{2}}\\ \frac{1}{\sqrt{2}} & -\frac{1}{\sqrt{2}} \end{array}\right)\left(\begin{array}{cc} \sqrt{80} & 0\\ 0 & \sqrt{20} \end{array}\right)\left(\begin{array}{cc} \frac{1}{\sqrt{10}} & -\frac{3}{\sqrt{10}}\\ \frac{3}{\sqrt{10}} & \frac{1}{\sqrt{10}} \end{array}\right)^{T}$$ This does not work. However if I multiply the second column of $U$ by -1: $$\left(\begin{array}{c} \frac{1}{\sqrt{2}}\\ -\frac{1}{\sqrt{2}} \end{array}\right)\mapsto\left(\begin{array}{c} -\frac{1}{\sqrt{2}}\\ \frac{1}{\sqrt{2}} \end{array}\right)$$  Everything works out.   The question is why? Both are normalized orthogonal eigencectors, shouldn't either one work? How do I choose?


I have a question of multivariable analysis and I don't know how to resolve this.     The $n \times n$ orthogonal matrices form a compact subset of $\mathbb{R^{n^2}}$?   I will be very grateful for the help.


Are players allowed to accept multiple levels of Disadvantage?

I'm fairly certain that you can't have Disadvantage more than once on the same roll for any reason. But it still seems possible to gain Disadvantage from multiple sources, even if every instance but the first is negated.  Can players intentionally use this to forego multiple penalties? For example, if a PC has 3 levels of exhaustion and is fighting a basilisk, can they say "I'm going to avert my eyes because I'll have Disadvantage on my attack roll anyway?" or should there be some further penalty?


A problem with the functional $F(\chi) = \int_{\mathbb{R}}(\chi'^2+\chi^2(1-\chi)^2)dx$.

Let $X:=\{\chi \in H^1_{\text{loc}}(\mathbb{R})\}$ such that $\chi(0)=\frac {1}{2},\; \chi(-\infty)=(0)$ and $\chi(\infty)=1$.  Consider the functional $$F(\chi) = \int_{\mathbb{R}}(\chi'^2+\chi^2(1-\chi)^2)dx$$  Prove that $F$ has a minimizer on $X$ and compute it.  Hints: Let ($\chi_n)_{n\in \mathbb{N}}$ be a minimizing sequence.  We may assume $0 \le \chi_{n} \le 1$, why?  Can we assume that each $\chi_n$ is monotone?   Extract a subsequence that is weakly converging in $H^1_{\text{loc}}(\mathbb{R})$, i.e., weakly on each bounded interval of $\mathbb{R}$. Study lower semicontinuity.   Deduce the Euler-Lagrange equation in the weak form for the minimizer.  Does the candidate minimizer satisfy the conditions at $\pm\infty$?   Show that the minimizer $\chi$ is more regular. Integrate the equation to compute the explicit solution.  This method of solving such a problem is new to me so I don't really understand the hints, can somebody help me in any way?


How can I get to the last wave of the pumpkin Moon in terraria 1.2.3 console?

I wanted to challenge the Pumpkin Moon. I keep getting to Wave 8 and the night ends. The problem might be that I'm not killing them fast enough. I tried an arena but it either fails, kills me, or is very slow. I have a lot of really good Items. I currently wear Dragon Armour, Spectral Armour and Titan Armour. If that makes a difference. I got the Horsemans Blade. I was able to get Red's Wings before they updated it. How do I get to wave 15 of the pumpkin moon? What strategy do I use?


PHP Gives Me Wrong Result Of Subtraction With Floating Number

I have this code :  <?php  $a = 991.3;  $float = floor($a); $float = $a - $float;  echo $float;   it gives me this as result:   0.29999999999995   why not 0.3? and how to get 0.3 instead of 0.29999999999995?


If time travels slower nearer gravity wells, why can't the galaxy rotation speeds being faster on the outer edges than the inner areas be explained by relativity? What necessitates dark matter?


Alternative Method to Acquire El Capitan Upgrade

Is there a way to acquire a copy of the El Capitan upgrade without downloading it first via the App Store, for example via a USB Drive? I know you can make a USB Drive after downloading El Capitan, but I am trying to skip the download itself.


Dimension for a closed subspace of $C[0,1]$.

Let $X \subset C^1[0,1]$ be a closed subspace of $C[0,1]$ (with sup norm).   Prove that $X$ has to be finite-dimensional.


Prove $\sum\limits_{r=0}^n{n\choose r}^2={2n\choose n}$

The question is to prove:$$\sum\limits_{r=0}^n{n\choose r}^2={2n\choose n}$$   using the binomial expansion of $(1+x)^n$ and $(1+x^{-1})^n$.   So firstly: $$(1+x)^n=\sum_{i=0}^n\frac{n!.x^n}{i!.(n-i)!}$$ $$(1+x^{-1})^n=\sum_{i=0}^n\frac{n!.x^{-n}}{i!.(n-i)!}$$ and we can work out that: $$\sum_{r=0}^n\left[\begin{pmatrix}n\\r\end{pmatrix}\right]^2=\sum_{r=0}^n\left(\frac{n!}{r!(n-r)!}\right)^2$$ but I am unsure of where to go from here


Whats the best way to make the background of these light balls transparent?

Magic wands doesn't work.  Tried using GIMP and zooming in to add to alpha channels but there must be a better way?


If $A$ is a matrix, then express it in the form $A^{-1} = A^2 + pA + qI$

I am given a matrix $ A = \begin{bmatrix}5 & 7 & 3\\ 1 & 5 & 2\\ 3 & 2 & 1\end{bmatrix}$ and I have to express it in the form $A^{-1} = A^2 + pA + qI$ I thought for a while but cannot think of anything else other than computing $A^{-1}$ and $A^2$ and then actually solving it. Or a better method to multiply $A$ on both sides and then compute the result requiring me to compute $A^3$ in that case. My question is, that is it possible to find out this expansion using a better and more efficient method because the one above seems quite tedious.


How is there no limit to a human lifespan again?

It's probably just misconstrued pop science, but I thought a read an article recently that said there's no known limit on how long humans can live. I could have sworn though that there were a few automatic processes that took place though, like that the chromosomes all shorten in length every time they're copied (is there any limit to that? Also, why does that matter?), the retinas in the eyes harden, the metabolism slows down, the heart muscles wears out, etc.  So, how could it be true?


Let $f(z)=\sum\limits_{n=0}^{\infty}a_n z^n$ be an analytic function in $|z|\leq R$ such that $|f(z)|\leq M$. Prove an inequality about $f$'s zero

Let $f(z)=\sum\limits_{n=0}^{\infty} a_n z^n$ be an analytic function in $|z|\leq R$, such that for all $z$, $|f(z)|\leq M$. Let $z_0$ be one of $f$'s zeros such that for all other zeros $z$, $|z_0|\leq |z|$. Let's write $d=|z_0|$. Show that $d\geq \frac{R|a_0|}{M+|a_0|}$.   I tried several directions here. For example, I used Cauchy's theorem to write out:  $$f(z_0)=\int\limits_{|z|=R}\frac{f(z)}{z-z_0}dz$$  such that: $$0=|f(z_0)|=\left|\space \int\limits_{|z|=R}\frac{f(z)}{z-z_0}dz\right|\leq 2\pi R\cdot \frac{M}{R-d}$$  I also tried looking at the circle $|z|<d$, such that since $z_0$ is $f$'s closest circle then, for all $|z|<d$, $f(z)\neq 0$. I used Cauchy's theorem here to show that:  $$\forall |z|<d, 0<|f(z)|=\left|\space\int\limits_{|\xi |=d}\frac{f(\xi)}{\xi-z}d\xi\right|\leq 2\pi d \cdot \frac{M}{d-|z|}$$  This didn't yield any results.  In order to get $a_0$ into this equation, I tried to say that this is in particular true for $z=0$, such that:  $$|a_0|=|f(0)|\leq 2\pi d\cdot \frac{M}{d}$$  But this didn't yield any results.   What would be a good direction for this type of question?


Best way to power 30-90 LEDs on 3.5 OR 12v

I have 6 3x10 blocks of LEDs (3 blocks red, 3 blocks white), all controlled individually.    r r r r r r r r r r + r r r r r r r r r r -   r r r r r r r r r r   (wired in parallel)  I'm controlling the blocks of LEDs using an Arduino MKRZERO.  I'm able to make 1 LED shine very bright per every output pin on the Arduino. However, I cannot make an entire block of lights shine very bright. They're actually very dim.  The I/O pins on the Arduino can only handle 3.5 volts.  If I by-pass the Arduino, I'm able to make a block of lights shine very bright.  At most I will have 3 blocks (90 LEDs total) shining, and at least 1 block (30 LEDs); except when it's off where obviously there would be no LEDs on.  The blocks will flash, only being on for no more than 1 second.   Everything needs to be powered by a 12v car charger (cig lighter port).  Currently I have an adapter that plugs into the car charger, and coverts to USB. I then took a USB cable and wired it to a voltage step down that goes to the Arduino. From the Arduino pins I have wires going to the light blocks.  The lights I'm using are 5mm clear straw hat red and white.    Multiplexing Where you can trick the brain into thinking all the lights are on. If I went this route, I would at most have 3 LEDs on at a time right? I've never seen this done with flashing blocks of LEDs, or this many... or really ever seen this.  Transistors To my understanding I can put 12 volts to all the lights, and use transistors connected to the Arduino that would act as a switch for each block of lights. One transistor per block of lights, right?  I'd like to go the easiest, and least expensive route.


Ambiguity between methods of calculating quartiles. Which method is more correct?

I am having confusion between two methods of calculating the first quartiles.  Let me explain by an example:  $A = [1,2,3,4,5]$  The method that I know:  To find the first quartile in the list above I first find the median = $3$ that is the 3rd element.  Now I split the list in the following fashion:  $(1,2)$  $3$  $(4,5)$  Now we take the list $(1,2)$ and we find the media between them that is $(1+2)/2 = 1.5$.  So according to my calculation the first quartile $Q_1 = 1.5$.  The nearest rank method()  $ n = \lceil\frac{P}{100} \times N\rceil$  So for the above list the $0.25$ percentile or the first quartile $Q_1$ will be   $\lceil \frac{25}{100} \times {5} \rceil = 2$  which is 2nd position.  So which is correct $1.5$ or $2$ ? Or does chosing any of them is fine ?  If I am correct in my original calculation why am I getting a difference between the 2 methods.  This different from  since my question involves in understanding which method is more correct.


Does Voldemort have the "Unicorn's blood curse"?

Quirrel drank Unicorn blood while Voldemort was inhabiting his body, and he himself drank a potion containing the substance (mixed with Nagini's venom) as well. So does that mean Voldemort has this unspecified "half-life curse"?  Two part question: Does Voldemort have the unicorn-blood curse persisting throughout the series? and If he does, how does it affect him?


I'am trying to write an equation where thee is this special caracter: \^{e}  \begin{equation} \^{e} = 1 \end{equation}   But the probleme is \^{e} is invisible, I see only “= 1”


Why did the format of full-form URLs to answers change?

As I pointed out in , the URL scheme for full-form links to answers has changed from:  https://site/questions/question-id/question-title/answer-id#answer-id   to:  https://site/questions/question-id/question-title#answer-id   Pretty much every link that redirects to an answer, including short-form links to answers (i.e. https://site/a/answer-id) and ?lastactivity links to questions, for example, now redirect to the latter form of URL, instead of the former one. (Interestingly, the responses tab in one's own user profile still consists of hard links to the old form.)  Why was this change made? It seems to have , as those are still looking for the old form of URL. Additionally, as per Tim Stone's comment, it also seems to have .  As a test for the above, I tried manually changing the URL to the old form, and it properly oneboxed in chat and properly changed the page and scrolled down.  It also briefly affected SmokeDetector (a community project that widely affects SE sites), until I filed an issue with them and had it fixed.  Was it done because search engines were showing multiple results, since it wasn't clear to them that they were looking at the same page since the URLs to answers were technically different?


Does $f(x)$ is continuous and $f = 0$ a.e. imply $f=0$ everywhere?

I wanna prove that   "if $f: \mathbb{R}^n \to \mathbb{R}$ is continuous and satisfies $f=0$ almost everywhere (in the sense of Lebesgue measure), then, $f=0$ everywhere."  I am confident that the statement is true, but stuck with the proof. Also, is the statement true if the domain $\mathbb{R}^n$ is restricted to $\Omega \subseteq \mathbb{R}^n$ that contains a neighborhood of the origin "$0$"?


I have been playing with the settings for the text object recently, and every time I add a new text object, I need to change the font to my favorite one. (Eurostile LT ExtendedTwo) Is there any way to change the default font so I do not need to change it every time I add a new text object?   Example: