Find $$\lim_{n \to\infty}{\left(\left(\frac{n}{n^2+1^2}\right) + \left(\frac{n}{n^2+2^2} \right)+ \dots +\left(\frac{n}{n^2+n^2} \right)\right)}$$   Is there some sort of a theorem or a method behind this type of limits? I mean, I can't even begin to do the task, since I have no clue.  Recent findings have shown that it might be related to Rieman's sums, yet again, this hardly makes the matters clear.


Will a battery short out when the terminals are directly connected together or will internal resistance save it?

I intended to make a simple electromagnet, then I saw  where the user is connecting wires together with no resistance at all. I was wondering why it doesn't short out and make the battery dead.   Does this  have internal resistance that will prevent shorting out?   If so what will be the current flowing through the battery and how long the battery can last powering the electromagnet, since capacity (like 1000mAh) is not mentioned on it?


What is "pure energy" in matter-antimatter annihilation made of?

I used to read the term "pure energy" in the context of matter-antimatter annihilation.  Is the "pure energy" spoken of photons? Is it some form of heat?  Some kind of particles with mass?   Basically, what does "pure energy" in the context of matter-antimatter annihilation refer to?


Proving $\rm \frac i 2 \ln\frac {x+i}{x-i}=\arctan x$ .

Proving $$\rm \frac i 2 \ln\frac {x+i}{x-i}  =\arctan x$$  I'd like to prove this identity without taking the derivatives and integrating, what are some cool ways to prove this?


Origin/reason for the expression "on the bus" instead of "in the bus"

This is sort of a follow up to my question .  I was told a while ago that the reason why we use "on the bus" instead of "in the bus" is because back in the day buses were open, that is, they didn't have a roof.   Is this story correct or is there another reason why the correct expression is "on the bus", in spite of the fact that when one gets on the bus, he is actually inside the bus?


There is a bug in ubuntu (cannot find a medium containing a live file system)

I cannot install ubuntu, and there is no way for me to submit a bug report, because I don't have ubuntu, because I can't install ubuntu.  I've followed all the instructions several times, and it just doesn't work on my system.  I know people are going to tell me to try a bunch of different stuff, but it just doesn't work. I've tried everything.  There is something wrong with ubuntu.  It does the same thing with Mint.  I guess there's not real way for me to report it though, so I don't know what to do.  It's weird though, because it works on a partition.  However, when I try to install it (I create a bootable USB drive (Yes, I've tried unebootin, I've tried dd, turning it into an img and leaving it as an ISO)), I can boot, it gives me the option to try or install ubuntu. I click install, and it says it cannot find a medium containing a live file system, whatever that means.  I'm using a Mid 2010 MacBook with an i5 Processor and an after market crucial 250 GB solid state drive.  Also, wanted to point out I've tried all this stuff in every usb slot.


pgfplots legend style for plots with error bands


Removing Unused WP SEO Codes display on html page

I recently noticed something displaying on my html source. Here are they.  <!-- This site is optimized with the Yoast WordPress SEO plugin v2.1.1 - https://yoast.com/wordpress/plugins/seo/ --> <meta name="robots" content="noindex,follow"/> <script type='application/ld+json'>{"@context":"http:\/\/schema.org","@type":"WebSite","url":"https:\/\/kl.ncc.my\/","name":"NCC KL \/ Selangor"}</script> <!-- / Yoast WordPress SEO plugin. -->          <script type="text/javascript">             window._wpemojiSettings = {"baseUrl":"https:\/\/s.w.org\/images\/core\/emoji\/72x72\/","ext":".png","source":{"concatemoji":"https:\/\/kl.ncc.my\/wp-includes\/js\/wp-emoji-release.min.js?ver=4.2.1"}};             !function(a,b,c){function d(a){var c=b.createElement("canvas"),d=c.getContext&&c.getContext("2d");return d&&d.fillText?(d.textBaseline="top",d.font="600 32px Arial","flag"===a?(d.fillText(String.fromCharCode(55356,56812,55356,56807),0,0),c.toDataURL().length>3e3):(d.fillText(String.fromCharCode(55357,56835),0,0),0!==d.getImageData(16,16,1,1).data[0])):!1}function e(a){var c=b.createElement("script");c.src=a,c.type="text/javascript",b.getElementsByTagName("head")[0].appendChild(c)}var f;c.supports={simple:d("simple"),flag:d("flag")},c.supports.simple&&c.supports.flag||(f=c.source||{},f.concatemoji?e(f.concatemoji):f.wpemoji&&f.twemoji&&(e(f.twemoji),e(f.wpemoji)))}(window,document,window._wpemojiSettings);         </script>         <style type="text/css"> img.wp-smiley, img.emoji {     display: inline !important;     border: none !important;     box-shadow: none !important;     height: 1em !important;     width: 1em !important;     margin: 0 .07em !important;     vertical-align: -0.1em !important;     background: none !important;     padding: 0 !important; } </style>   I have checked all my plugins, i find no where to delete them. Does someone here facing same issue? I just want the robot meta tag to display. Just to delete the rest of coding above. Any solutions?


I created a simple crontab job.   It should execute every 15 minutes to alert me that I need to take a short break. However, it does not work. I don't know why.   Please help me if you have experience with crontab. I used the command crontab -e to create this file and save it.  # Edit this file to introduce tasks to be run by cron. #  # Each task to run has to be defined through a single line # indicating with different fields when the task will be run # and what command to run for the task #  # To define the time you can provide concrete values for # minute (m), hour (h), day of month (dom), month (mon), # and day of week (dow) or use '*' in these fields (for 'any').#  # Notice that tasks will be started based on the cron's system # daemon's notion of time and timezones. #  # Output of the crontab jobs (including errors) is sent through # email to the user the crontab file belongs to (unless redirected). #  # For example, you can run a backup of all your user accounts # at 5 a.m every week with: # 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/ #  # For more information see the manual pages of crontab(5) and cron(8) #  */15 * * * * /home/galaxy/Documents/projects/Bash/cron_job.sh   This file is supposed to execute the script cron_job.sh every 15 minutes.  This is a Bash shell script that has a chmod value of 500. It contains one command to create a new gnome-terminal and immediately run a command inside that new terminal to cat the file take_a_break. That is a text file with a simple message telling me to take a break.   Running from the terminal directly either the shell script or just running the command contained inside of it works flawlessly, but the crontab job does not work at all. Maybe I formatted something incorrectly.   Here is the contents of the file cron_job.sh:   #!/bin/bash  gnome-terminal -e "bash -c \"cat /home/galaxy/Documents/ascii/take_a_break; exec bash\""   The reason I put the command inside a shell script is because cron did not run it previously, but cron also does not run the shell script.   I checked and it seems to me that I have the correct syntax.  Also if it is relevant, trying to run the crond command gives an error:  $ crond No command 'crond' found, did you mean:  Command 'cron' from package 'cron' (main) crond: command not found


What happened to my camera and how to set it back to default?

My camera became all distorted and if I add a different camera, it does the same thing.


android studio error: 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference

This is the error. I tried a few things, but still got no results.   Process: com.lucastan96.flashchat, PID: 6114 java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference     at com.lucastan96.flashchat.ChatListAdapter.getView(__ChatListAdapter.java:101__)     at android.widget.AbsListView.obtainView(AbsListView.java:2366)     at android.widget.ListView.makeAndAddView(ListView.java:2052)     at android.widget.ListView.fillUp(ListView.java:820)     at android.widget.ListView.layoutChildren(ListView.java:1793)     at android.widget.AbsListView.onLayout(AbsListView.java:2165)     at android.view.View.layout(View.java:20672)     at android.view.ViewGroup.layout(ViewGroup.java:6194)       boolean isMe = message.getAuthor().equals(mDisplayName);     setChatRowAppearance(isMe, holder);      String author = message.getAuthor();     holder.authorName.setText(author);     String msg = message.getMessage();     holder.body.setText(msg);      return convertView;   and the line 101 is at "boolean isMe = message.getAuthor().equals(mDisplayName);"


Find the $1000$th digit after the decimal point of $\sqrt{n},$ where $n=\underbrace{11\dots1}_{1998 \text{ 1's}}$

Find the $1000$th digit after the decimal point of $\sqrt{n}$, where $n=\underbrace{11\dots1}_{1998 \text{ 1's}}$.   Obviously, $\underbrace{11\dots1}_{1998 \text{ 1's}}=\dfrac{1}{9}\left(9\cdot10^{1997}+9\cdot 10^{1996}+\dots+9\right),$ so we want to find $\left(\dfrac{10^{1998}-1}{9}\right).$ If only there was some way to convert this expansion into some closed form. I'm not sure if calculus would be useful. The problem asks for a single digit, so if we consider repeating digits, everything will be a lot easier. There seems to be a pattern in the decimal expansions of numbers consisting of only $1.$  For instance,  $$\sqrt{1}=1,$$ $$\sqrt{11}=3.3166247...$$ $$\sqrt{111}=10.5356537...$$ $$\sqrt{1111}=33.3316666...$$ $$\sqrt{11111}=105.408728...$$ $$\sqrt{111111}=333.333166...$$ $$\sqrt{1111111}=1054.09250...$$  Every term of the form $\displaystyle\sum_{n=0}^{2k+1}10^n$ has $k+1$ $3$'s at the beginning and $k+1$ 3's right after the decimal expansion, followed by one $1,$ and $2(k+1)$ $6$'s. Proving this would prove that the $1000$th digit is $1.$ This is the same as showing that $\sqrt{\left(\dfrac{10^{2m}-1}{9}\right)}=\dfrac{10^{m}-1}{3}+\dfrac{1}{3}-\dfrac{1}{6}\cdot 10^{-m}+\epsilon_m$ where $|\epsilon_m|<10^{-2m}.$  Edit: the previous question I asked was inspired by the current one, but the previous question seemed to have a rather unpleasant answer, so I changed it.


C++ string to int without using atoi() or stoi()

Hi I am new to C++ and trying to do an assignment where we read a lot of data from a txt file in the format of   surname,initial,number1,number2   I asked for help before an someone suggested reading the 2 values as string then use stoi() or atoi() to convert to int. This works great, except I need to use this parameter "-std=c++11" for compiling or it will return an error. This is not a problem on my own computer which will handle "-std=c++11", but unfortunately for me the machines which I have to present my program on does not have this option.  If there another way which I can convert string to int that doesn't use stoi or atoi?  Here is my code so far.  while (getline(inputFile, line)) {     stringstream linestream(line);      getline(linestream, Surname, ',');     getline(linestream, Initial, ',');     getline(linestream, strnum1, ',');     getline(linestream, strnum2, ',');     number1 = stoi(strnum1);     number2 = stoi(strnum2);      dosomethingwith(Surname, Initial, number1, number2); }


tikz bounding box of a cubic Bézier curve

This document  \documentclass[DIV=16]{scrartcl} \usepackage{tikz} \pagestyle{empty} \begin{document} \hrule \begin{center} \begin{tikzpicture}[scale=.3]     \draw[domain=-1:5] plot (\x,{0.5*\x*\x*(\x-3)}); \end{tikzpicture} \end{center} \hrule \begin{center} \begin{tikzpicture}[scale=.3]     \draw (-1,-2) .. controls (1,7) and (3,-20) .. (5,25); \end{tikzpicture} \end{center} \hrule \end{document}   produces this output:  So, the second picture has a much larger bounding box, which is probably due to the control points. Is there a possibility to force tikz to calculate the real extrema rather than just looking at the terminal points and the control points?  Edit: The bounding box shall automatically be correct WITHOUT adding new points to the curve. It is okay for me, if you say that there is no possibility without changing tikz itself. This just means that I can ask the tikz development for this feature without overlooking something obvious.


What if the hard disk is partitioned into more than 26 sections in Windows?

As we know, in Windows the partition location is prefixed with [a-z]:. What happens if there are more than 26 partitions?


R equivalent of ArcMap split by Attributes?

I have a shapefile of 50 polygons. I've read it into R. Now I want to use R to export 50 shapefiles, one for each polygon. This seems like an intuitive application of . But I'm having a devil of a time doing it.  I tried a for loop (like ).  STNCODES <- unique(ptsbuf_400@data$STNCODE) for (i in 1:length(STNCODES)) {   tmp <- data[ptsbuf_400@data$STNCODE == STNCODES[i], ]   writeOGR(tmp, dsn=getwd(), STNCODES[i], driver="ESRI Shapefile",            overwrite_layer=TRUE) }   I get the following error:     Error in data[ptsbuf_400@data$STNCODE == STNCODES[i], ] :    object of   type 'closure' is not subsettable   This seems to be the cause of the error, but I'm at a loss how to fix it:     data[ptsbuf_400@data$STNCODE == STNCODES[i], ]   Amtrak station data     works--likely there is some difference between the spatial object generated by readOGR/writeOGR and read_sf and write_sf--the latter seems to be a vector, while the sp object is not?


How to disable validation property in mvc web api c# that allow html content

I need to create a web api that accepts a multipart form request that contains input for text, file fields. Now I'm facing a problem that I cannot send html text through the text field.  [HttpPost] public HttpResponseMessage SampleController() {     try     {         var httpRequest = HttpContext.Current.Request;         var sendItem = httpRequest.Params["Body"];     } }   The code above shows the api controller. It accepts a 'Body' field that contains Html contents. When parsing the request by controller caught an Error shown below.     System.Web.HttpRequestValidationException: 'A potentially dangerous Request.Form value was detected from the client (Body="
Hai
").   Web.config:  <system.web>   <compilation debug="true" targetFramework="4.7.2" />   <httpRuntime targetFramework="4.7.2" /> </system.web>   How to solve this issue so that it can accept text with html?


I am using sed for string replacement in a config file.  User has to input the string salt and then I replace this salt string in the config file:  Sample config file myconfig.conf  CONFIG_SALT_VALUE=SOME_DUMMY_VALUE   I use the command to replace dummy value with value of salt entered by the user.  sed -i s/^CONFIG_SALT_VALUE.*/CONFIG_SALT_VALUE=$salt/g" ./myconfig.conf   Issue : value of $salt can contain any character, so if $salt contains / (like 12d/dfs) then my above sed command breaks.  I can change delimiter to !, but now again if $salt contains amgh!fhf then my sed command will break.  How should I proceed to this problem?


Prove $99^{100}>100^{99}$ using binomial theorem

Prove $0<(1+\frac{1}{n})<3$ and hence prove $99^{100}>100^{99}$.  I did the first part and showed $0<\frac{1}{n^{n-1}}\le3$ and hence $0<(1+\frac{1}{n})<3$. But for the second bit, I don't know how to incorporate the first bit to help me prove th inequality.


Prepared vs. Prepare & Was drunk vs. Got drunk

"I'm preparing for my next exam". "I'm getting prepared for my next exam" "He was drunk" vs. "He got drunk" Does "Get" change the meaning of "Drunk" & "Prepare"? Also, is "Be prepared" or "Be prepare"?


How to fix this error when running sudo apt-get update?

I'm getting the error below when I run: sudo apt-get update  Any idea how this can be fixed?


Is there a way to see all Steam achievements in one account?

I want to check which of my games need the least achievements to achieve a perfect status.   The only way to see the game stats that I know of is to go to the games list from a player profile but that's too tedious, especially with over 250 games with varying degrees of play-times and achievement completion.


How to create a wrapping horizontal list

I'm attempting to create a list view in Android that shows clickable items that wrap horizontally much like the "To" field in the OS X and iPhone's Mail programs. They have a horizontal list of names that wrap vertically and each name is a separate object, the list is not just a single string. My questions are:   Is there a way to do this with a ListView or some other type of AdapterView? Everything I've seen and experimented with is either horizontal scrolling or vertically  stacking, but not horizontal wrapping. Are you aware of an existing app with available source that has a view like this that I could look at as an example? The Google Mail/SMS apps just has a single string in the too field that isn't clickable.


Steam not opening - "tar: This does not look like a tar archive"

I am new to Linux and I have Ubuntu 17.04 64-bit (Budgie).  I cannot open steam. It is updated to latest version. When I open it it pops up but after some time it disappears. When I try to run it from a terminal I get this output:  tar: This does not look like a tar archive xz: (stdin): File format not recognized tar: Child returned status 1 tar: Error is not recoverable: exiting now find: ‘/home/ghazi/.steam/ubuntu12_32/steam-runtime’: No such file or directory


How to Make Indoor Photography Not Blurry

I am a beginning photographer with a Canon Rebel XTI. I'm trying to get indoor portraits of my son, but I can't seem to get non-blurry photos because the shutter speed is too slow as I need to let the light in, however he is moving thus causing the blurriness. Whenever I change the shutter speed, the photos become too dark. If anyone has any tips, techniques or settings on the camera they could suggest that would be most appreciated. Maybe I need a different lens?   Thank you!


Do some file get excluded from being saved in the locate database?

Does the locate database not save certain files? Like are there files that excluded from the database by default?


How can I set footnotes to different font and size to main text?

I have to prepare a document with the following criteria - 1.5 spacing, text in Times New Roman, Size 12 (with footnotes throughout in Calibri, Size 10). Since I'm using luaLaTeX to get the fonts I'm not sure if the  answers apply. In my MWE I am able to get the times font and have the 1.5 line spacing but how can I set the footnote font to size 10 and Calibri?  \documentclass[12pt,a4paper,onecolumn]{article} \usepackage[margin=1.5in,footskip=0.25in]{geometry} \usepackage{fontspec} \usepackage{microtype} \setmainfont{times} %\setmainfont{Calibri} \usepackage{titling} \setlength{\droptitle}{-2cm} \usepackage [autostyle=once,english=british]{csquotes} \usepackage [UKenglish,american,british]{babel} \usepackage[notes, backend=biber, includeall=false,]{biblatex-chicago}  \usepackage{setspace} %\doublespacing \onehalfspacing  \begin{document}  This is test.\footnote{Test footnote.}  \end{document}


How should I phrase an important question that I need to ask a professor?

When needing to ask a professor about something important and potentially delicate, what is an appropriate way to phrase the question or write the email?  Examples include:   Requesting a recommendation letter Asking for exceptions to policy (e.g., ignoring a course prerequisite, rescheduling an exam) Asking if you can do research with them, join a group, get into a program Scheduling a meeting, exam, or defense Letting them know about a change of plans Letting them know about a life event affecting your work or studies (e.g., wedding, funeral, sickness, vacation)


How do I make a curved surface out of rectangular blocks?

For a Peggle-like game, I want to make blocks that follow a curve, like this:    The blocks would then disappear as the ball hits them.  I managed to draw some horizontally, but I'm having trouble making them follow a path:    How do I do this? Do I need to create Box2D objects with custom vertices?


My 3 y old DD is refusing to sit on potty/toilet after a bad spell of constipation?

My 3 year old daughter is fully potty/toilet trained apart from wearing a nappy for bedtime. She had constipation recently which was very painful for her. This has cleared now, but she is still refusing to sit on the potty or toilet and holding in her wee until it literally burst out of her. I have asked if she wants to wear a nappy and she refuses that as well. Please help!!!


How do I check if an image field is empty in a template file?

I am trying to check if the user_picture field is empty using the twig template, but I am not able to do this.  I tried lots of ways:-  {% if node.user_picture.value %} {% if node.user_picture.entity %} {% if content.user_picture.value %} {% if content.user_picture|render.entity %} {% if content.user_picture|render %}     Sample of code:    {% if node.user_picture.value %}
User-picture 02
     {{ user_picture }}   {% else %}
Anymonus-picture 02

   {% endif %}


Record a list of installed packages and configurations before installing a higher version of Ubuntu?

I now have 12.04 installed, and would like to install 14.04.   Is it recommended to create a list of installed packages, so that I can install them back after installing 14.04?  What about those packages installed with no record in dpkg, such as those installed by configure, make and make install from source?  If yes, how? Is it also recommended to save the configurations of 12.04 and installed packages somewhere, so that I can make the same configurations after installing 14.04?  If yes, how to do that (efficiently)?   Thanks.


I need help with increasing the size of the file-system partition. Partitioning-o-phobia!

When I firstly installed Ubuntu I gave it 20GB of space for the filesystem. ...time passed and I get a message "the system has only 300MB available" so I need to enlarge the filesystem.  Here's my partition table:      I'm a total noob to partitioning and I have a horrible experience with it; once i had this problem:  on my notebook. Thanks to the great support I got, I gained the tumbleweed badge and I couldn't fix it and I had to re-install windows. The notebook didn't have much important data but this computer's much more important to me. I have backed up the data on the "Database" partition.  anyways  I need step-by-step instructions how to take space from the "Database" partition to enlarge my "filesystem" partition. and what about that red exclamation mark at /dev/sda6?  how do I deal with it? ... what is it?? The red exclamation is not gone!  Tell me any extra information you need to know. Thanks in advance! :D


Is DDR4 RAM compatible in a DDR3 RAM slot?

I'm looking to get a RAM upgrade for my SONY VAIO VPCEH25FM. If I get DDR4, is it compatible with a DDR3 slot?


Creating New Site Collection "2013 experience version will be used"

We are using, i think, SharePoint Online as a part of Office 365. Perhaps I have the terminology correct, it is confusing.  When I go to the SharePoint Admin Center and lick on site collections I noticed that all of our site collections are Version 2013.  When I go to create a new site collection the window says: "2013 experience version will be used".  Is 2013 the newest version? I have read about 2016. Can you create a site collection using a 2016 experience? It seems as though even though we user SharePoint through Office 365 there are still versions that match up with the on-prem versions?  My questions:  1) Can I create a site collection using 2016  2) What do the versions mean, and will there always be a version even though we are using SharePoint through Office 365.


Blur the whole document and add a demo watermark on each page

This  is about blurring text but it is not about blurring everything in the document.  shows how to add the watermark over all pages (but it does not work with pictures,  shows how to do it with some extra star over pictures).   How can I blur the whole document and add a DEMO watermark on each page and possibly leave only one sentence without blurring?


Is the image of a null set under a differentiable map always null?

Let $n$ be a positive integer.  $\;  $  Let $f : \mathbb{R}^n \to \mathbb{R}^n$ be everywhere .  Let $S$ be a subset of $\mathbb{R}^n$ with  zero.  Does it follow that $\{f(s) : s\in S\}$ has Lebesgue measure zero?  (I know it would if $D(f)$ is continuous.)


Savings accounts are insured by CDIC up to $100k. Is it a total of $100k across all savings accounts I have with different banks or 100k per account?


I've read that function composition "generally does not commute."  Not counting compositions involving the identity function, and compositions of a function and its inverse, are there examples of functions on the reals (for example) $f, g$ where $fg = gf$ outside of these cases?


Parallel DNA double-helices with Watson–Crick base-pairing: Why do they not occur?

I know that parallel DNA helices exist and are governed by Hoogsten base pairing, but why can’t they be possible with Watson-Crick pairing? In the diagram below, if we were to flip one of the strands while keeping the other the same, it appears as though hydrogen bonding is still possible.  The only specific suggestions that I could find was because of the DNA replication process and the negative polarity of hydoxyl group on the phosphates. Moreover, after flipping one strand, the DNA nucleotides form enantiomers. Are these possible reasons, or are there others?


Contact still visible in Whatsapp after deleting out of my contactlist from my phone

I deleted a contact/number out of my contact list from my smart phone. But if I open WhatsApp I can still see that same contact/person that I deleted earlier. How is this possible?


Given Newton's third law, why are things capable of moving?

Given Newton's third law, why is there motion at all? Should not all forces even themselves out, so nothing moves at all? When I push a table using my finger, the table applies the same force onto my finger like my finger does on the table just with an opposing direction, nothing happens except that I feel the opposing force. But why can I push a box on a table by applying force ($F=ma$) on one side, obviously outbalancing the force the box has on my finger and at the same time outbalancing the friction the box has on the table? I obviously have the greater mass and acceleration as for example the matchbox on the table and thusly I can move it, but shouldn't the third law prevent that from even happening? Shouldn't the matchbox just accommodate to said force and applying the same force to me in opposing direction?


international travel with dual citizenship and 2 passports

I am a dual citizen with Philippines and US. My US passport just expired and I am renewing it, no rush. Out of curiosity, I want to know if it is possible to travel with just my Philippine passport. Filipinos need a visa to enter the US, but I am a US citizen. I assume that leaving the US would be no issue, but upon re-entry where would I go for customs, a US citizen with a foreign passport?  DUPLICATE QUESTION FLAG: A similar question has been asked of a US-Canada dual citizenship, but Canadians do not need a visa to enter the US. And I am asking about more than just entry to the US, but also leaving the US, and details as to where I would go for re-entry in US customs.


Files in the same directory seen differently by different tools

I have installed chocolate(packet manager) programs at:  C:\ProgramData\chocolatey\bin  And also installed fzf(search tool) as GVIM plugin.Accidently installed at the same dir:   C:\ProgramData\chocolatey\bin  There is weird situation where different tools see different files in this dir:   cmd.exe - see fzf.vim files  cmder.exe - see choco files explorer - see choco files  totalcmd.exe -see fzf.vim files nerdtree(gvim) - see chocolatey/bin as one name and there are fzf.vim files   I have installed Cygwin and Gow(linux commands at Win) projects at my Windows 7 64bit with NTFS partition. Does it have a connection with path that sometime is typed in "linux way" using / insted \?  I had similar situation with some Cygwin dir before.


Can textures be set to specific size and tiled that way?

Not sure how to explain this, since English is not my native language, but Sketchup automatically tiles everything and you just have to set a length and width of the texture in the material section, you set it in inches, centimeters or whatever and it will be that size no matter what face you apply it to.  In Blender I can't seem to find that, I know that you can down and upscale textures in the uv editor and make them tile, but what if I want the same texture (to remain the same size, for example 5x5 centimeters) on 2 different size faces? I can try by downscalling it, but that's not precise, so can I adjust the texture size automatically and not in relation to the size of a face I'm working on?  For example I have a grass lawn on one part of the map in Blender and another one on the other part of the map, how do I make the texture to be the exact same size here and there, no matter what the size of those lawns are?


Radius of convergence of entire function

Let $f$ be an entire function on the complex plane.      Is the radius of convergence of $f$ around any point $z_0$ infinite? If so, why?   Thank you.


Why does the version of Java verified by Oracle differ from the version shown at the command line?

Questions  Why do versions differ?   Should we trust Oracle's verification routine?    In some cases, the  is different from the version shown at the command line.   Example    That example, in detail  According to Oracle in the browser:    Java 7 Update 9   According to the Java Console:   Java Plug-in 10.9.2.05 Using JRE version 1.7.0_09-b05 Java HotSpot(TM) 64-Bit Server VM   According to the java command:   sh-3.2$ java -version java version "1.8.0-ea" Java(TM) SE Runtime Environment (build 1.8.0-ea-b58) Java HotSpot(TM) 64-Bit Server VM (build 25.0-b02, mixed mode)


Can we do anything about suggested edits being wrongly approved by weighting votes?

The case in point is .  Here, The edit was correctly rejected by one user and incorrectly approved by 3.  The underlying problem is that the three users (apparently) have little / no understanding of the language being used in the solution.  Editor 1: Approved     Total Rep 3721     Total Answers: 132     Objective-C specific¹ answers: 2     Objective-C specific score: 0   Editor 2: Approved     Total Rep 3134     Total Answers: 28     Objective-C specific answers: 0     Objective-C specific score: 0   Editor 3: Approved     Total Rep 2721     Total Answers: 151     Objective-C specific questions: 7     Objective-C specific answers: 1     Objective-C specific score: 4    Editor 4: Rejected     Total Rep 10746     Total Answers: 414     Objective-C specific answers: about 20, some duplicates between tags.     Objective-C specific score: >30, some duplicates between tags.   Here the pattern seems to be that those with low scores in the relevant tag, unsurprisingly, mistakenly approved an invalid flag.  Would a viable solution be to give higher weighting to those votes where the user voting has a given score in the answers tags?  ¹ Those with tags I associate with Objective-C, , , etc. I may well have missed some.


When asking using smartctl, I got the answer:     Sector Sizes:     512 bytes logical, 4096 bytes physical   When asking using fdisk, I got the answer:     Sector size (logical/physical): 512 bytes / 512 bytes   When asking using blockdev, I got the answer:  > RO    RA   SSZ   BSZ   StartSec            Size   Device rw   256   > 512  4096          0   1000204886016   /dev/sdc   Why are there differences? What are the consequences of this? What do I have to do?


i have an error in the numbering of the tables. some of the number are missing and don't know what is the problem. the following picture illustrate the problem. please i need your help!


Measure theory convention that $\infty \cdot 0 = 0$

In the preface of Terry Tao's notes on measure theory he states that in the extended real number setting we adopt the convention that $\infty \cdot 0 = 0 \cdot \infty = 0.$   He explains that it's a useful convention which makes it natural to define integration from below (e.g. integrals as supremums of nonnegative simple functions). He seems to be saying, "Let's define it this way, because it makes our lives simpler." Is more justification not needed?  This 'fact' helped me during my midterm today in showing that $\mu(E \times \mathbb{R})=0$ for any measure-zero set $E$, but I felt sleazy using it.  Any thoughts (philosophical or otherwise) on why or how we can do this and still have self respect as mathematicians?


Is there a way to have an encrypted folder on macOS with fast read/write operations?

I've tried and used Disk Utility to create an encrypted image, so I can store data in it securely. However, when I tried to write files to this image, the write operation was too slow (to write ~50 GB of data, it would take 1 day as estimated).  My question: is there a robust alternative that allows creating an encrypted space in the hard disk to store data with fast read/write operations?  Edit: Adding details:  Device :   Apple MacBook Pro (15-inch, Mid 2012)   Processor : 2.6 GHz Intel Core i7 Memory : 8 GB 1600 MHz DDR3 Hard drive : APPLE HDD HTS547575A9E384   Rotational Rate:  5400 Partition Map Type:   GPT (GUID Partition Table)  OS version : 10.12.1   I am transferring data to an encrypted image on the hard drive. Its encryption type is 128-bit AES.  Source of data  The external hard drive that I am transferring data from : StoreJet Transcend Media.   Partition Map Type : GPT (GUID Partition Table)  Encrypted. Encryption Type : AES-XTS


Need help to understand the output of ls -l command. I created one file testa in my home directory. When I run the ls -l command it shows up with two similar names. What does the symbol (~) mean with the file "testa". Below is the sample output:  testa testa~


Is it possible for the MD5 hash of a string to be the original string itself?

For example, I have a string s and the MD5 of s is m. So is it possible for s=m.  Now it can be found by iterating through all possible combinations but there are 2^128 combinations to check through and I do not have the resources to do so. Is any such case possible and if it is possible then what is the case?


Difference between standard beta and unstandard beta distributions?

What is the difference between standard beta and unstandard beta distributions? How to understand in an article if it is not described if it is standard or not?


Units of "mean free time" of a wave/particle

Suppose you have a wave $\phi$ with a complex angular frequency:  $$\phi = e^{j\omega t} = e^{j(\omega_R+j\omega_I)t} = e^{j\omega_Rt} e^{-\omega_It} = e^{\frac{-t}{\tau}} e^{j\omega_Rt} $$  Here, $\tau = 1/\omega_I$ is the time necessary for the amplitude to decay with $1/e$.  Now my question: what is the unit of $\tau$?    I would think that the unit is seconds. In this case, the exponent becomes dimensionless and this suits with the definition time necessary for the amplitude to decay with $1/e$. $\tau$ is the inverse of the imaginary part of the radial frequency. So one can argue that the unit can be second/rad.   What is the unit of $\tau$ and do you need to multiply or divide by $2\pi$ in the calculation of $\tau$ (to get rid of the radians)?


Do you see the outside world from inside the black hole (can you see past the horizon from inside it)?

I have read these questions:           And none of these answered the viewpoint of somebody being inside the black hole. What I found out on this site is that for an infalling observer, nothing special happens (other then being spagettified) but clocks seem to run normally, and an infalling observer would not even notice the event horizon.  For an infalling observer's view, there is no such thing as event horizon. What I did not find is what does somebody see when inside the black hole? Can you look out? Can I see past the horizon?  Question:   Do I see the outside world when looking out from inside the black hole? Can I see past the horizon from inside it?


Combinatoric meaning to $1+2+\dots+n=\frac{n(n+1)}{2}= {n+1 \choose 2}$

It is well known that $$ \sum_{k=1}^{n} k = \frac{n(n+1)}{2} .$$ As the story goes, Gauss notices that there are $n/2$ pairs of numbers that add up to $n+1$, hence the formula above. But obviously the right hand side is ${n+1 \choose 2}$, namely $$ \sum_{k=1}^{n} k = {n+1 \choose 2} .$$ Is there a "combinatorial proof" of this second equation? I am trying to see the connection between the sum (and Gauss' method) to the problem of choosing $2$ objects from $n+1$ objects.


My misto sprays in a stream. I have cleaned it amd follow the instructions. What can I do to correct this problem?


OR condition in Views Contextual Filters

I have a Content Type named "Match" which has a local and visitor. Both are node references to a Content Type named "Team".  In Views I need to ask for matches of a specific team, no matter if that team is the local or the visitor. In contextual filters I can set a value for "local" and for the "visitor" each one in particular. So I guess I need an OR condition in this case.  Does anyone know how to solve that problem?  Edit: I found  module already but that's the problem, my website is too big and currently in production so we don't want to have problems because of bugs or something.


Are mounts proficient in armour (barding)?

Mounts can be given barding to duplicate the effect of armour at 4x the cost. However, barding makes no statement about armour proficiency, nor does the stat block for some of the more obvious mounts (Riding Horse, Warhorse, etc.).  If a mount is given barding, is it proficient in it? If not, how is it possible for them to gain proficiency?  The penalties for wearing armour without proficiency are no spellcasting and disadvantage on ability checks, saving throws, and attacks that use Strength or Dexterity.  Assuming they are not proficient, do mounts with barding have disadvantage on Strength and Dexterity -based ability checks and saving throws?  And finally, non-humanoid creatures are not explicitly stated to use either Strength or Dexterity in their attacks, but I would assume physical attacks have to use one of these two, so:  Assuming they are not proficient, do mounts with barding have disadvantage on attacks?


One object having two different colors and distortions

So my question is how do I fix an object that was made by joining two separate objects together. Specifically what I want to fix is the color issue, I need it to be one color and without any distortions.(greyish black parts) Would be glad if anyone can provide feed some back.


C++ does not have native support for lazy evaluation (as Haskell does).  I'm wondering if it is possible to implement lazy evaluation in C++ in a reasonable manner. If yes, how would you do it?  EDIT: I like Konrad Rudolph's answer.  I'm wondering if it's possible to implement it in a more generic fashion, for example by using a parametrized class lazy that essentially works for T the way matrix_add works for matrix.  Any operation on T would return lazy instead. The only problem is to store the arguments and operation code inside lazy itself. Can anyone see how to improve this?


Can't I use two different condition at "on" in a join?

Tried this :  myStructs = from MyObject s in MyObjects             join c in Categories on s.CategoryID equals c.Item1 && s.Stars equals c.Item2             select s;   but seems I can't wrote 2 condition at the join? Where am I wrong? On SQL this can be done as well...


Evaluating the limit of $\left(\frac{\sin x}{x}\right)^\frac{1}{x^2}$ for $x\to 0^+$

What is   $$\lim_{x \to 0^+} f(x)\quad\text{ where }\quad f(x) =\left( \frac{\sin x}{x}\right)^{1/x^2}$$  ? The problem suggests to use a Taylor expansion, but it is not clear to me what to expand.


Exporting as obj.All at once (noob question)

So i wanted to ask you guys if you can select all the objects you want to export all as different files.Instead of exporting one at a time.


Are "over-visible" and "over-visibility" correct/idiomatic words?

I want to say that someone is too visible, as in the following sentence:     Unlike philosophers who suffer from invisibility in the society,   sociologists enjoy over-visibility.   Is the use of "over-visibility" in the above sentence correct?


How to safely remove proprietary Intel driver

I recently installed the proprietary Intel drivers for my Toshiba Satellite A105 s4284 running Ubuntu 14.10. Nouveau was working just fine, I was just attempting to make it so that I was able to run CS:S (no need for explanation on that.)  Long story short, I went and downloaded the Intel Graphic Drivers for Linux* from . After downloading and installing the .deb, I ran intel-linux-graphics-installer which opened up a window that downloaded & installed the open Intel drivers. I then rebooted, and it's slow. Very slow, especially on 3D effects and when I hit Alt+Tab.  Now, I don't know if the previously installed Nouveau drivers are conflicting with these new Intel drivers (if that's the issue, what should I do about fixing it?) What I do know is that my system isn't behaving right and I want it to (obviously.) If removing the Nouveau drivers isn't the solution, how can I safely remove the just-installed Intel drivers?  Does anyone have any suggestions?


Group of order 10 has an element of order 5, without using Cauchy's or Sylow's theorems

This is almost a duplicate of the following questions (but, read further):      But, I wasn't able to apply the proof to my case of a group of order 10 and an element of order 5.  In my case, if I try a proof by contradiction, I'm left with the fact that every element in $G$ is of order 2, but if I divide them into subgroups, every subgroup is of order 2, and has one unique element.  I also tried other methods to prove the theorem, but couldn't come up with anything meaningful.  I'm a beginner in the field, and am not familiar with theorems such as Cauchy's or Sylow's theorem (I'm aware of Lagrange's theorem). Therefore, please try to provide a simple answer, thanks!


How does Newton's third law hold during arm wrestling?

What happens when two people are arm-wrestling and one is winning? How is the torque that they apply on each other's arms different? And how do they follow Newton's third law of rotational motion? For example - Let's say you have arm A on the left and arm B on the right (representing the arms). arm A exerts 50 N towards the right. arm B exerts 40 N to the left. I.e. Force𝐴𝑜𝑛𝐵=50𝑁 and Force𝐵𝑜𝑛𝐴=40𝑁. Applying Newton's third law now, Force𝐵𝑜𝑛𝐴=50𝑁 and Force𝐴𝑜𝑛𝐵=40𝑁. Thus there is a net force of 90N in each direction. How can one person be winning in this scenario?


Let $\left| {{a_{ii}}} \right| > \sum\limits_{i \ne j} {\left| {{a_{ij}}} \right|} $.Why does $A$ is nonsingular? .

Let $A \in {M_n}$ and $\left| {{a_{ii}}} \right| > \sum\limits_{j \ne i} {\left| {{a_{ij}}} \right|} $.Why does $A$ is nonsingular?


MWE:  \documentclass[]{article}  \usepackage{xcolor} \usepackage{color} \usepackage{listings}  \definecolor{maincs}{RGB}{255,0,0} \definecolor{secondarycs}{RGB}{255,179,246} \definecolor{tertiarycs}{RGB}{79,139,87}  \lstset{ language=[LaTeX]TeX, basicstyle=\ttfamily\normalsize, columns=fullflexible, breaklines=true, texcsstyle=*\color{maincs}, texcs={documentclass,begin,end,chapter,section,subsection,label,alpha}, moretexcs=[2]{usepackage,input}, texcsstyle=*[2]{\color{secondarycs!80!black}}, moretexcs=[3]{\n,\,renewcommand,tablename,contentsname,indexname,chaptername, figurename,listfigurename,listtablename,hyphenation,sin,cos, index,printindex,item,jobname,date,makeindex,maketitle,title,author,tableofcontents}, texcsstyle=*[3]{\color{tertiarycs}}, inputencoding=utf8, extendedchars=true, literate={ö}{\"{o}}1 {ü}{\"{u}}1 {Ş}{\c{S}}1 {ç}{\c{c}}1 {İ}{\.{I}}1 {ı}{\i}1,}  \begin{document}  \begin{lstlisting} \begin{eqnarray*} x + y &=& z + t\\ &=& u + 6\\ \end{eqnarray*} \end{lstlisting}  \end{document}   and displaying    But that I want    That is, \\ add to list. What will I do?


How to change the title of the current terminal tab using only the command line

None of the currently posted answers works/answers the question. As per my original question, neither setting PS1 nor PROMPT_COMMAND had any effect.  Using only a command at the command prompt, how do I change the title of the current terminal tab? Many posts suggest this: echo -en "\033]0;New terminal title\a"  but it does nothing. None of the current answers works (some don't answer the question), so for clarity:  Once the title is changed, I don't want it to change if I change directory etc I don't want the same title on all tabs. I only want to set the title for the tab I run the command in I want multiple tabs to each have different titles  Also, the PROMPT_COMMAND variable is not set in my terminal sessions. If I set it: PROMPT_COMMAND='echo -en "\033]0;New terminal title\a"'  it has no effect. What is the correct command?  FYI, the output of uname -a is:  Linux d136172 3.13.0-45-generic #74-Ubuntu SMP Tue Jan 13 19:36:28 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux


Sum of reciprocals of primes factorial: $\sum_{p\;\text{prime}}\frac{1}{p!}$

The series $$\sum_{p\;\text{prime}}\frac{1}{p}=\frac{1}{2}+\frac{1}{3}+\frac{1}{5}+\frac{1}{7}+\frac{1}{11}+\cdots$$ diverges as is well known. How about the following? $$\sum_{p\;\text{prime}}\frac{1}{p!}=\frac{1}{2!}+\frac{1}{3!}+\frac{1}{5!}+\frac{1}{7!}+\frac{1}{11!}+\cdots$$ Its convergence is easily obtained by comparing with the series $e=\sum_{n=0}^\infty\frac{1}{n!}$. Numerically, we get $$\sum_{p\;\text{prime}}\frac{1}{p!}\simeq 0.675198$$ Can we find the specific value?


Imagine this directory structure:  app/    __init__.py    sub1/       __init__.py       mod1.py    sub2/       __init__.py       mod2.py   I'm coding mod1, and I need to import something from mod2. How should I do it?    I tried from ..sub2 import mod2 but I'm getting an "Attempted relative import in non-package".  I googled around but found only "sys.path manipulation" hacks. Isn't there a clean way?      Edit: all my __init__.py's are currently empty    Edit2: I'm trying to do this because sub2 contains classes that are shared across sub packages (sub1, subX, etc.).  Edit3: The behaviour I'm looking for is the same as described in  (thanks John B)


Collective Noun: Is the possessive with "children" singular or plural?

Which is preferred:     Children will have their picture displayed.   OR   Children will have their pictures displayed.   The actually photographs of children not drawings


Is there a way to install Windows over the network?

I work at my university's tech support center, and we frequently have customers who need their Windows OS's reinstalled. We use USB drives, DVDs, and CDs that contain the installation .iso file, since we can boot to them.    My question is, is there a way for us to install Windows from a centralized server? That is, could we boot to the NIC on the customers' computers and install Windows from there? The closest thing I have found is using  to do this, and while it works, the software is very picky because SERVA needs to have the client computer's NIC driver in order to work. Since we see hundreds of customers a day, we cannot guarantee to be able to load all drivers, and therefore we can't help everyone.


Can a string be used as array index in C?  Ex: String      Corresponding value "ONE"       1 "TWO"       2 "FIVE"      5 "TEN"       10  When a string in the above list is passed to the function, the function must return the corresponding value indicated above. Can this be achieved by declaring a constant array with string as index  int *x; x["ONE"]  = 1; x["TWO"]  = 2; x["FIVE"] = 5; x["TEN"]  = 5;  return x["string received by the function"];   The above logic does not work as expected; is there a workaround to implement the above logic in order to have a string-indexed array?


WHY is there conflict between python versions?

I know that ubuntu 18.04 LTS needs python 3.6 for doing a lot of its stuff, but I need to run a lot of python 3.7 applications and I don't get that why there is a conflict between them, I had to go over all non-running programs in /usr/bin and change the line #!/usr/bin/python3 to #!/usr/bin/python3.6 and I'm not sure if there are some more files I should change, and I'm worried someday my PC won't boot up 'cause of that :(  Is there a way to make that conflict go away and use only python3 command for everything?  P.S. I did a lot of searching and came up with nothing so if this is a duplicate question I'm sorry  Thank you all in advance :)  Edit:  This is the error log output when I run a system program with python3.7  Traceback (most recent call last):   File "/usr/bin/add-apt-repository", line 11, in <module>     from softwareproperties.SoftwareProperties import SoftwareProperties, shortcut_handler   File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 28, in <module>     import apt_pkg ModuleNotFoundError: No module named 'apt_pkg' Error in sys.excepthook: Traceback (most recent call last):   File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook     from apport.fileutils import likely_packaged, get_recent_crashes   File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>     from apport.report import Report   File "/usr/lib/python3/dist-packages/apport/report.py", line 30, in <module>     import apport.fileutils   File "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in <module>     from apport.packaging_impl import impl as packaging   File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 24, in <module>     import apt   File "/usr/lib/python3/dist-packages/apt/__init__.py", line 23, in <module>     import apt_pkg ModuleNotFoundError: No module named 'apt_pkg'  Original exception was: Traceback (most recent call last):   File "/usr/bin/add-apt-repository", line 11, in <module>     from softwareproperties.SoftwareProperties import SoftwareProperties, shortcut_handler   File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 28, in <module>     import apt_pkg ModuleNotFoundError: No module named 'apt_pkg'   It's also the same if I run an app that needs 3.7 with the 3.6 version.


What is considered an enemy for an Orc's Aggressive trait?

Volo's Guide to Monsters says that you may play an  character, which gives you the following trait,  (p. 120):  Aggressive. As a bonus action, you can move up to your speed toward an enemy of your choice that you can see or hear.  My question is: what can be considered as an enemy for this trait to apply?  Anything I want Any living creature, including non-hostile ones Only creatures that are hostile to me (actual enemies)  For example, can I choose a tree as my enemy, justifying it by a "Me find tree insult my race, me hate tree, me ANGRY!", and then bonus-move toward said tree?


Locked votes can be changed by editing a post

This is somewhat related to this question:    But relates more to the senario that when a vote has been locked for a particular post, the user can edit the post (by maybe just adding new line or something) and subsequently the user can then change the vote the that was previously locked.  It's a strange feature but essentially renders the functionality of locking votes useless for users with enough points to edit posts.


Adding an [AuthorYear] block at the beginning of bibliography entries

I want to add a block at the beginning of my bib entries of the form      [Lastnameauthor(s) Year]   When the shortauthor field is defined it should use this field +Year instead. The following example is fairly minimal:  \begin{filecontents*}{test.bbx} \ProvidesFile{test.bbx}  [\abx@bbxid $Id: test.bbx,v 0.9d 2010/09/03 20:11:58 lehman beta $]  \RequireBibliographyStyle{authoryear}  \DeclareBibliographyDriver{article}{%   \usebibmacro{bibindex}%   \usebibmacro{begentry}%   %---add something here---   \usebibmacro{author/translator+others}%   \setunit{\labelnamepunct}\newblock   \usebibmacro{title}%   \newunit   \printlist{language}%   \newunit\newblock   \usebibmacro{byauthor}%   \newunit\newblock   \usebibmacro{bytranslator+others}%   \newunit\newblock   \printfield{version}%   \newunit\newblock   \usebibmacro{in:}%   \usebibmacro{journal+issuetitle}%   \newunit   \usebibmacro{byeditor+others}%   \newunit   \usebibmacro{note+pages}%   \newunit\newblock   \iftoggle{bbx:isbn}     {\printfield{issn}}     {}%   \newunit\newblock   \usebibmacro{doi+eprint+url}%   \newunit\newblock   \usebibmacro{addendum+pubstate}%   \setunit{\bibpagerefpunct}\newblock   \usebibmacro{pageref}%   \usebibmacro{finentry}}  \endinput  \end{filecontents*} \begin{filecontents*}{MeineBib.bib}   @article{example,  author={Firstname Lastname and First Last},   title={Title},  journal={Journal},  year={Year},   pages={Pages}, }    \end{filecontents*}  \documentclass[12pt,ngerman,    ]{scrartcl} \usepackage[ngerman]{babel} \usepackage{filecontents} \usepackage[babel,german=quotes]{csquotes} \usepackage [bibstyle=test]{biblatex} \bibliography{MeineBib}  \begin{document} \tableofcontents \cite{example} \printbibliography\end{document}   I'm guessing the solution lies here  DeclareBibliographyDriver{article}{%       \usebibmacro{bibindex}%       \usebibmacro{begentry}%       %---add something here---       \usebibmacro{author/translator+others}%   but I can't find out how. It should look like this  which is an existing style (natdin) in BibTeX, but not in biblatex.


Ring of matrices isomorphic to $O := \left\{a+b\frac{1+\sqrt{D}}{2}: a, b \in \mathbb{Z} \right\}$

Let $D$ be an integer such that it is not a perfect square in   $\mathbb{Z}$.       If $D \equiv 1$ mod $4$, the set $$T:= \left\{\left( \begin{matrix} a & b  \\ \frac{(D-1)b}{4} & a+b \\ \end{matrix} \right) : a, b \in  \mathbb{Z} \right\}$$ is a subring of $M_2(\mathbb{Z})$ which is isomorphic   to the ring $$O := \left\{a+b\frac{1+\sqrt{D}}{2}: a, b \in \mathbb{Z} \right\}.$$   My problem is to find an isomorphism. However, I find this relation : $$\det \left( \begin{matrix} a & b  \\ \frac{(D-1)b}{4} & a+b \\ \end{matrix} \right)$$ $$= a(a+b)-\frac{b^2(D-1)}{4}$$ $$= \left(a+b\frac{1+\sqrt{D}}{2}\right)\left(a+b\frac{1-\sqrt{D}}{2}\right)$$  and $D \equiv 1$ mod $4$ $\iff$ $\left(\frac{1+\sqrt{D}}{2}\right)\left(\frac{1-\sqrt{D}}{2}\right) = -k$ for some $k \in \mathbb{Z}$  Does someone could give me a little hint to help me complete this problem?


Consider a measurable space $(\Omega,\mathcal{F})$. Is the supremum of an uncountable family of Borel measurable functions of the type $f:\Omega\to\mathbb{R}$ a Borel measurable function?


Finite group generated by two elements; what can we say about another element?

If G is a finite group generated by $a,b \in G$, both $a$ and $b$ having order 2, what can we say about the order of another element $xy \in G$?  I was thinking that we can conclude that $xy$ has finite order because it is contained in G, but nothing else can be concluded. Is this correct or am I missing something?


Does this exist: software for noise cancellation

I'm aware that the best option for noise cancelling is to buy myself a pair of noise cancelling headphones...  But is there any software available that would use the pc mic and headphones to block background noise?


I want to recreate the following diagrams   Here is my MWE  \documentclass{standalone} \usepackage{tikz} \usetikzlibrary{calc,intersections}  \begin{document} \begin{tikzpicture}      \draw [->, name path=x] (-1,0) -- (9.5,0) node [right] {$x$};     \draw [->] (0,-1) -- (0,6) node [above] {$y$};      \node at (0,0) [below left] {$0$};      \coordinate (start) at (1,0);     \coordinate (k) at (2.6,0) ;     \coordinate (c) at (4.5,3.5);     \coordinate (end) at (9,0);     \draw [thick,name path=curve] (start) to[out=70,in=180]         (c) to[out=0,in=180] (end);         \draw [dashed] (2.6,2.81)node [above,left] {$(a,f(a))$} --(k) node [below=1mm] {$a$};         \draw [dashed] let \p1=(c) in (c) -- (\x1,0) node [below] {$x$};         \draw (4.5,3.5) node [above] {$(x,f(x))$};  \end{tikzpicture} \end{document}


How to show that $\mathbb Q(\sqrt 2)$ is not field isomorphic to $\mathbb Q(\sqrt 3).$

How to show that $\mathbb Q(\sqrt 2)$ is not field isomorphic to $\mathbb Q(\sqrt 3)?$   My text provides the hint as: Any isomorphism from $\mathbb Q(\sqrt 2)\to\mathbb Q(\sqrt 3)$ is identity when restricted to $\mathbb Q.$  Ya! I can see that: $\mathbb Q(\sqrt 2)\simeq\mathbb Q[x]/\langle x^2-2\rangle$ and $\mathbb Q(\sqrt 3)\simeq\mathbb Q[x]/\langle x^2-3\rangle.$ Now if $\phi$ be such an isomorphism then $\phi:1+\langle x^2-2\rangle\mapsto1+\langle x^2-3\rangle.$ Hence the restriction of $\phi$ over $\{q+\langle x^2-2\rangle:q\in\mathbb Q\}$ remains the identity.  Now what?


I'm making a program that will print out a set of savings for tomorrow only, and i wanted to specify what date tomorrow was, which i did like this:  Tomorrow = datetime.date.today() + datetime.timedelta(days=1)   Which gives the outpu:  2016-04-11   as you can see, it does give tomorrows date like planned, except it does it in the YYYY-MM-DD format, which is my issue. is there a way to have tomorrows date printed in the DD-MM-YYYY format? Cheers


Does Ubuntu 18.04 Server Raspberry Pi support hidden wireless?  I try to figure out this issue for a few days. could you give me advance. thanks  1)/etc/netplan/50-cloud-init.yam <- I don't have any idea to set hidden wifi.  network:    version: 2   renderer: networkd   wifis:     wlan0:       dhcp4: no       dhcp6: no       addresses: [192.168.1.31/24]       gateway4: 192.168.1.254       nameservers:         addresses: [8.8.8.8]       access-points:         myssid: {password: mypasswork}       ###no any idea for hidden wifi###   2)/etc/network/interfaces <- not working  allow-hotplug wlan0 iface wlan0 inet static address 192.168.1.31 netmask 255.255.255.0 gateway 192.168.1.254 wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf     network={     ssid="myssid"     scan_ssid=1     psk="mypassword" }


How to prove that a compact set in a Hausdorff topological space is closed?

How to prove that a compact set $K$ in a Hausdorff topological space $\mathbb{X}$ is closed? I seek a proof that is as self contained as possible.  Thank you.


Copy editor badge after 2000 reputation?

I currently have less than 2000 reputation. When I reach 2K reputation, I will receive the .  My question is: right now my edits are being counted for the Copy Editor badge; these edits are also reviewed before they are accepted. But after I've earned 2K, there won't be any peer reviews. So will my edits still  be counted and tracked for the Copy Editor badge?


I want to use MS Power Point and Excel In Ubuntu

For my office work, I want to use MS Power Point and MS Excel. I want to know if Microsoft Office is compatible with Ubuntu? If yes, how can I install it?  If it is not compatible then what is the alternate to MS Office?  Thanks.


MS Word document shows question mark symbol � on GitHub

I am hosting an HTML file, created using MS Word, on GitHub. For some reason, when I open the site, it shows question mark symbols in place of other symbols. .  I have no background in anything related to this (no web programming or MS Word) so I am confused. Why is this happening and how can I fix it?  Thanks!  Edit: .


Do technical indicators actually work while analyzing stocks?

I have tried various indicators such as SMA's, EMA's, stochastics, Bollinger bands etc, while trying to analyze a stock, but they often are only as effective as making a wild guess on picking a stock. My question here is, how can you use the indicators to effective use and which one of these is the most reliable(if any)?


Can I add a resistor to a 120V-24V power source to convert the amperage from 2.9 to 1.8?

I have an old Kodak printer dock for an Easyshare camera but I'm missing the power source for it. The dock requires 24V 1.8A power so I bought a power supply marked 24V (24.2 measured) and 70W but the printer only powers up and then shuts down after a few seconds. If the problem is the supply amperage is too high can I use a resistor inline somewhere to lower the amperage? As you may have guessed, I've done some research but I'm new to this kind of thing.


Android Null object reference on location

Okay so I am using this GPS location from  and I keep getting Null Object reference and not sure why.Here is my code:   boolean permissionGranted = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED;      if(permissionGranted)     {         if (GPS.sharedInstance(AppDashboard.this).canGetLocation() && GPS.sharedInstance(this).isPermissionEnabled()) {             double lat = GPS.sharedInstance(AppDashboard.this).getLatitude();             double lon = GPS.sharedInstance(AppDashboard.this).getLongitude();             Log.e(TAG, "Location: " + lat + "/"+ lon);         }         else         {             Log.e(TAG, "Can't get GPS locations");         }     } else {         ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 200);     }   My Manifest:  <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-feature android:name="android.hardware.location.gps" />   My Logcat:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference at com.gpsApp.utility.GPS.getLatitude(GPS.java:113)   And GPS Class 113  public double getLatitude() {     if (_locationManager != null) {         _latitude = _location.getLatitude();     }      return _latitude; }


Show that the series $\sum_{n=1}^\infty \frac{a_n}{S_n}$ diverges

Given that the series $\sum_{n=1}^\infty a_n$ of positive terms diverges and that $S_n = a_1 + a_2 + ... + a_n$  prove that $\sum_{n=1}^{\infty} \frac{a_n}{S_n}$ also diverges.


I want to make a logistic model from my survey data. It is a small survey of four residential colonies in which only 154 respondents were interviewed. My dependent variable is "satisfactory transition to work". I found that, of the 154 respondents, 73 said that they have satisfactorily transitioned to work, while the rest did not. So the dependent variable is binary in nature and I decided to use logistic regression. I have seven independent variables (three continuous and four nominal). One guideline suggest that there should be 10 cases for each predictor / independent variable (Agresti, 2007). Based on this guideline I feel that it is OK to run logistic regression.    Am I right? If not please let me know how to decide the number of independent variables?


Child Of Constraint Set Inverse with Python

When I try to use the "set inverse" operator in python there comes an error that it missed a context called "constraint". But I did it exactly like in the Info Panel.  bpy.ops.constraint.childof_set_inverse(constraint="Child Of", owner='BONE')   The Name of the constraint is correct and the also the owner


Cardinality and infinite sets: naturals, integers, rationals, bijections

I have alot of questions.   Do Infinite sets have the same cardinality when there is a bijection between them? Are $\mathbb{N}$ and $\mathbb{Z}$ infinite sets? I assume they are, but why? Why does there not exist a bijection between them? Why do $\mathbb{N}, \mathbb{Z}, \mathbb{Q}$ have the same cardinality? I assume there exists a bijection between them, but how can I find this function?


Does any problem arise when the order of an elliptic curve is equal to its prime field modulus?

Regarding cryptographic schemes in elliptic curve cryptography, is there a problem with having the order of an elliptic curve being equal to its prime field modulus?  That is, an elliptic curve where $\#E(\mathbb{F}_p) =p$ for some prime $p$?  As I understand it, this seems to be an optimal curve because by the lagrange's theorem the order of an elliptic curve's subgroup must be divisible by the order of the elliptic curve. But if the order of an elliptic curve is prime, that then that means that any point in this curve is a generator that produces all of the points in $E$ and has a cofactor of $1$. For example, .  So, is there some kind of 'gotcha' with this sort of elliptic curve? Something that might allow an attacker to easily solve it by some math trick? Of course, assume for an elliptic curve some large prime $p$ but with the same properties.


It suddenly came to my mind that this is quite strange:        Obama, with whom I was at school, has just come to live in our street.   Who are you hanging out with?      Obviously, both sentences are correct, so is "with whom".     But... why do you say "who are you hanging out with", not "whom"?


I'm trying to use Mike42 Classes Library, already connected to the printer and everything works fine. then I'm trying to print hebrew letters and Getting "?????" or Some Gibberish Strings.  Anyone already tried also?


ANDROID SQLITE: How to retrieve primary key of a certain row

Pretty simple question, but I still did not find my answer around the internet: Basically I just finished creating a new row and inserted it into the database, but I want to save the newly created primary key of that row. How do I access it? As it stands, I am trying to use the rest of the column's values to find a certain row, but I am getting the SQLiteException : bind or column index out of range.  Here is the code for my current function trying to get the keyid:          public String getPrimaryKey(String gameTitle, String gameType, String calories, String hours, String minutes) {         Cursor cursor = db.query(TABLE_NAME, null, null,new String[]{gameTitle, gameType,calories, hours, minutes},null, null,null,null);          if(cursor.getCount()<1)         {             cursor.close();             return "????";         }         cursor.moveToFirst();         String keyid = cursor.getString(cursor.getColumnIndex(KEY_ID));         cursor.close();         return keyid;      }   The strings being passed in the parameters are the other columns that I am trying to use to access the primary key.  Thank you very much!


Is the least inaccessible cardinal equivalent to the first aleph fixed point?

Let $I$ be the least / first inaccessible cardinal. As inaccessible cardinas are all aleph fixed points, and they are regular, so each inaccessible cardinal is an aleph fixed point after the previous one. My question is:      Is $I$ the first fixed point of the function $\alpha \mapsto \aleph_\alpha$?   My background for this question is that while I was reading about ordinal collapsing functions (specifically about collapsing large cardinals) I found that by collapsing the least inaccessible cardinal ($I$) you got the first omega fixed point, which gave me the question, as if $I$ is the first fixed point then it is also a fixed point of the collapsing function, which wouldn’t be as useful.


How much weight can screws in drywall hold?

I've always had the question of how much weight can a single screw into a drywall withstand?  For instance, I would like to do things like this:    It's hung with 5 screws. The whole thing weighs approximately 50kg (110 pounds) so we can say that each screw holds approximately 10kg (22 pounds).  The person who installed it said it was fine, but is it really?  Do somebody know a study or some numbers regarding how much weight this material can stand?  EDIT: Just to clarify, it's not screwed to the studs. It's screwed to the drywall.


Output rows in SQL table in one field with comma's

I have a table that lists items and section that they belong to and the subsections within that. Each item can belong to any number of sections and subsections and doesn't have to belong to all. Roughly like:  Item|Section|SubSection 1   |1      |1a 1   |1      |1b 1   |1      |1c 2   |1      |1b 1   |2      |2a 1   |2      |2b 2   |2      |2a 2   |2      |2c   Is there a select string or function that would allow me to pull out the Item, Section and then a string with the subsection with a comma or other delimiter.  i.e the results from above would look like:  Item|Section|SubSectionString 1   |1      |1a,1b,1c 2   |1      |1c 1   |2      |2a,2b 2   |2      |2a,2c   Kind regards  Matt


How to Use Pillow (PIL) Inside Blender Addon?

I want to do  from PIL import Image   inside a Blender addon. But it throws this error at me:  ModuleNotFoundError: No module named 'PIL'   Thus I've tried to install Pillow via pip like this:  import subprocess import ensurepip ensurepip.bootstrap() pybin = bpy.app.binary_path_python subprocess.check_call([pybin, '-m', 'pip', 'install', 'Pillow'])   But this doesn't work, either.  What am I doing wrong? :)


Apex batch class :System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out


I have just bought a shiny new Canon MG6250 multifunction printer/scanner and connected it via LAN. Installing the printing side of things was a breeze, however, I cannot work out how to set up scanning.   I installed the  from Canon's site but when I open GIMP or Simple Scan, they say there is no scanner detected. Using GIMP's 'update scanner list' button to search for the scanner does not find it.  How do I tell Ubuntu, GIMP or Simple Scan to look on the network for the scanner? Is there another utility especially for this?


How do I get a book graphic and description from the Amazon Book API?

sends an ISBN number to Amazon and gets back a small bit of XML including author, title, and publisher.  However, I also want to get small, medium and large graphic and book descriptions of the title.  Problem: I can find no REST URL examples/documention that work, either at Google or when logged into my "AWS Account" at Amazon Associates.  I find a lot of examples from 2003-2005 but they are all out-of-date and give errors, it seems that Amazon's cloud web services have obfuscated their simple REST API documentation for their books.  Can anyone point me to some documentation on how I can get detailed information about books at Amazon via REST/XML?   Here's what I have tried so .


Similar to , we want to sort by one element, then another.  we want to achieve the functional equivalent of   SELECT * from Table ORDER BY x, y     We have a class that contains a number of sorting functions, and we have no issues sorting by one element. For example:    public class MyClass {     public int x;     public int y; }    List<MyClass> MyList;  public void SortList() {     MyList.Sort( MySortingFunction ); }   And we have the following in the list:    Unsorted     Sorted(x)     Desired ---------    ---------    --------- ID   x  y    ID   x  y    ID   x  y [0]  0  1    [2]  0  2    [0]  0  1 [1]  1  1    [0]  0  1    [2]  0  2 [2]  0  2    [1]  1  1    [1]  1  1 [3]  1  2    [3]  1  2    [3]  1  2   Stable sort would be preferable, but not required. Solution that works for .Net 2.0 is welcome.


Do I need a transit visa travelling from London via Canada to the Dominican Republic?

I've got a Pakistani passport and a valid student visa for England. I'm going to travel to the Dominican Republic with a stay of 17 hours at a Canadian airport. Do I need a transit visa?


Given a polynomial function f(x), prove that f(a) - f(b) is divisible by a - b. I tried it with a few examples and it is coming out to be true. Is it true and if so how do we prove it ? Thanks


2.3 Tablet bootloop, trying to pull logfile with root adb

I have an old android tablet (2.3) which I've had for a number of years now. I've been trying to get access to the application data storage, because I had some important documents stored in a notes application. Using ADB in the past I've pulled the entire user storage directory to my PC, which I still have a copy of.  But now, it's stuck in a bootloop. When it turns on it shows the Polaroid logo, then blue screens for a bit then starts booting up. It shows the android booting logo with the windows-xp-like slider going across the screen. After 10 seconds that freezes and the tablet reboots.  I'm still able to access the tablet's root shell using ADB (I see # instead of $) and I've been trying to pull the log file to see why the tablet has been unexpectedly bootlooping. This is funny because I've only been pulling files from the tablet using ADB, and there is no touch so I don't understand how it's managed to damage it's own filesystem.  Upon browsing through the filesystem in root ADB, I've found that files I've pulled in the past from the user storage, don't appear under /mnt/sdcard and I can't locate them in the /data folder.  Is there any way that I can use ADB to pull the log file off the tablet?


Where to store program settings instead of HKEY_LOCAL_MACHINE?

I have some program settings that are currently stored in HKEY_LOCAL_MACHINE. Due to Vista and locked down users, some users don't have permission to HKEY_LOCAL_MACHINE, and those values don't really belong to HKEY_LOCAL_USER either (it has to be the same for all users), what's the best alternative location for storing these?  Majority of settings are stored in the DB already, but there are some that the program needs to know about before connecting to the DB. Ideally I'll like a way to implement this without needing to check what operating system is running.  This is for a desktop app written in Delphi.


Understanding a derivation of bias correction for the Adam optimizer

I'm reading  about the Adam optimizer and went up until the bias-correction section; in the paper they estimate the bias of the moving average of the squared gradient. These are the equations they use:    Where $v_{t}$ is the moving average of gradient squared, $g_{i}$ is gradient at the $i^{th}$ iteration and $\beta_{2}$ is a moving average parameter.  I don't understand how they make any of these transitions from the first row to the second and on to the third one. Could someone explain what rules are allowing them to do so ?


$\sum_{n=0}^{\infty}a_n$ diverges in the regular term but is Cesaro summable     Prove $a_n/n\to 0$ when $n\to \infty$   We used the definition of the Cesaro sum and obtained:  $\lim_{N\to \infty}\frac{1}{N+1}\sum_{n=0}^{N}S_n$=$\lim_{N\to \infty}\frac{1}{N+1}\left (  \sum_{n=0}^{N-1}S_n+\sum_{k=0}^{N}a_k\right )$=$\sum_{n=0}^{N-1}\frac{S_n}{N+1}$$+\sum_{k=0}^{N}\frac{a_k}{N+1}$=$L$  but from here we're kind of stuck  *($S_n$ is the partial sums of $a_n$)


How do you change TTY font size before login?

I am able to change the font in TTY by adding this script to ~/.profile:  if [ "$TERM" == "linux" ]; then      setfont /usr/share/consolefonts/Uni3-Terminus32x16.psf.gz fi   However this script is executed after login. The login prompt message is still tiny. How do I change the font size before login?


Is it possible to write the '%' symbol in text in LaTeX?

I'm a beginner trying to use LaTeX. I tried to write a sentence which includes the %-symbol using \text{}, but the function that the %-symbol has in LaTeX seems to block me from using it in a normal text sentence.  \documentclass{article} \usepackage[utf8]{inputenc} \begin{document} \maketitle  \text{I can't use the %-symbol} \end{document}


Is it possible to play Splitscreen Online?

Is it possible to play splitscreen online in starwars battlefront on the ps4. I've tried to invite my friends to the party, and then play, but that doesn't work. Please respond to me if you know


SEO - alt and title attributes for thumbnail images in recommended products?

I think that title almost explains it. What is best for SEO to use in section Recommended products for alt and title attributes of thumb images? Should they maybe be empty? Recomendded products are show on a page where one main product is opened, below main product in slider (as seen in most web shops).


C# cast options, is there any difference other than syntax?

I just ran across another way to cast objects in C#.  I have always used (CastType)variable.  I just noticed some code using variable as CastType.  The latter reminds me of VB.  Is there a difference between the two methods of casting other than syntax?


Is it allowed/desirable to post code snippets?

Instead of asking a question I would love to share the one or other code snippet I have created that is too small to make a full article on e.g. CodeProject.com or CodePlex.com.  Question: Would it be a good idea to post it as a Stack Overflow question? Or are there any other suggestions how to share it?  (Of course I could post it on my own weblog and then twitter about it, but I would love to put it in more of a programming context)


Prove that $\sqrt{2} +\sqrt{n}$ is irrational

Suppose $\sqrt{2} + \sqrt{n}$ is rational,  so it can be represented like so: $\sqrt{2} + \sqrt{n} = {x \over y}$  then  $\sqrt{2} = {{x \over y} - \sqrt{n}}$  so $\sqrt{2} = {x - y\sqrt{n}\over y}$  but $\sqrt{2}$ is irrational, which leads to a contradiction.  Does this proof make sense?  edit: fixed some mistakes


In the English textbook for third-graders in Vietnam, there’s a segment that goes:  My question is: is this a correct way to address your name as a teacher (as in Miss Hien) to your student? Shouldn’t it just be “I am Hien.” instead? Thank you for your input.


Retrieving Maxwell's equations from the minimum action principle

I'm currently working at the start of Alexei Tsvelik's book Quantum Field Theory in Condensed Matter Physics. I'm kinda stumped on a few essential steps.  Starting with the action:  $$S = \int dt \int d^3 x \mathcal{L}_{\mathrm{EM}} = \int dt \int d^3 x \left( -\frac{1}{4} F_{\mu \nu} F^{\mu \nu} + j_\mu A^{\mu}\right).$$  In the absence of any sources $j_\mu = 0$ and $c=1$, which after pulling in the negative sign implies  $$S = \frac{1}{2}\int dt \int d^3 x  \,\,\left(E^2 - B^2\right)$$ The next step is to take $\vec{E} = -\vec{\nabla} \phi + \partial_t \vec{A}$ and $\vec{B} = \vec{\nabla} \times \vec{A}$. Letting $\phi = 0$ and directly inserting these into the above yields:  $$S = \frac{1}{2} \int dt \int d^3 x  \,\left( (\partial_t \vec{A})^2 - (\vec{\nabla} \times \vec{A})^2 \right) $$  Now considering $\vec{A} = \vec{A}_0 + \delta \vec{A}$ as some minimal change in our vector potential, with $\vec{A}_0$ gives a minimum for the action and putting this into the above expression we have: $$\delta S = \int dt \int d^3 x \left(\partial_0 \vec{A}_0 \partial_0 \delta \vec{A} + \left(\vec{\nabla} \times \vec{A}_0\right)\cdot\left(\vec{\nabla} \times \delta \vec{A} \right) \right)+ \mathcal{O}(A^2)\,\,\,\,\,\,\, (1)$$ where I have the term  $$\mathcal{O}(A^2) = \int dt \int d^3 x \left( (\partial_0 \vec{A}_0)^2 + (\partial_0 \delta \vec{A})^2 - (\vec{\nabla}\times\vec{A}_0)^2-(\vec{\nabla}\times \delta\vec{A})^2\right)$$  The next step is where I lose our author and go from "Oh ok I get this" to "completely clueless". He rewrites $\delta S$ as:  $$\delta S =  \int dt \int d^3 (\delta x) \vec{A} \mathcal{F(\vec{A}_0)}+ \mathcal{O}(A^2)$$  where $\mathcal{F} = \frac{\delta S}{\delta A}$. What is the purpose of $x\to \delta x$ in the above expression? Is the functional derivative $\mathcal{F}$ a vector quantity? He has it bolded with a bolded $\vec{A}$ in the above expression. One last question takes the above expression further. We assume $\delta \vec{A}$ vanishes at infinity, as it should, and integration by parts yields:  $$\delta S =  -\int dt \int d^3 x \left( \partial^2_0 \vec{A}_0 - (\vec{\nabla} \times \vec{\nabla})\times \vec{A}_0  \right)\delta \vec{A}\,\,\,\,\,\,\,\, (2)$$ How exactly did we go from (1) to (2)? Thanks I appreciate your time!


How to set NACK on bad PEC in TWI used for SMBUS (ATMega8)

I want to implement the SMBUS protocol in my AVR device (ATMega1284P), which will have the role of slave. I need to support the PEC (Packet Error Code) feature, which means that the master device (which is not mine) will send a "checksum" byte after the last byte of its command, to which I need to respond with ACK or NACK depending on its validity.  I have some experience with I²C/SMBUS/TWI as I used it before, but it seems I can't solve this particular problem. Apparently, with AVR's TWI implementation I need to decide for ACK or NACK in the byte received prior to the PEC value; i.e., in response to a previous TWSR = 0x80 (data has been received). The problem is, I don't know in advance if the PEC I will be receiving next will be valid or not! Apparently setting or clearing the TWEA bit is only effective for the next byte to be received. Example:  1 - ME     = Prepare for TWI slave operation; set address and ACK 2 - MASTER = Writes SLA+W (gets ACK from step #1) 3 - ME     = INT with TWSR 0x60; Sets ACK/NACK for next byte (ACK) 4 - MASTER = Sends Byte (gets ACK/NACK from step #3) 5 - ME     = INT with TWSR 0x80; Sets ACK/NACK for next byte (ACK) 6 - MASTER = Sends Byte (gets ACK/NACK from step #5) 7 - ME     = INT with TWSR 0x80; Sets ACK/NACK for next byte (ACK) 8 - MASTER = Sends PEC Byte (gets ACK/NACK from step #7) 9 - ME     = INT with TWSR 0x80 (PEC); too late to ACK/NACK PEC value!   As you can see, I should decide for ACK/NACK in step #9, but the master's already got an ACK set at step #7!  As much as I digged into the docs, I cannot find a way to respond with NACK "on the fly" because the ATMega sets the interrupt AFTER sending the ACK (or NACK). TWSR will be either 0x80 or 0x88, which means "byte received, ACK sent" and "byte received, NACK sent" respectively.  Aside from implementing a bit-banging SMBUS library, is there some way to solve this?  Thank you.


Joint distribution of $\min(X_1,\ldots,X_n)$ and $\max(X_1,\ldots,X_n)$.

Let $X_1,\ldots,X_n$ be independent random variables with common cumulative distribution function $F$. I am trying to find the joint cumulative distribution function of $$U=\min(X_1,\ldots,X_n)\quad\text{and}\quad V=\max(X_1,\ldots,X_n).$$ The result that I get is $$F_{U,V}(u,v)=F(v)^n-(F(v)-F(u))^n,$$ but this seems wrong because letting $u\to\infty$ gives the marginal CDF $$F_V(v)=F(v)^n-(F(v)-1)^n,$$ while it should be $F_V(v)=F(v)^n$. I obtained the result as follows $$\begin{align} F_{U,V}(u,v) &= P(U\leq u,V\leq v) \\ &= P(V\leq v)-P(U>u,V\leq v) \\ &= P(X_1\leq v,\ldots,X_n\leq v)-P(u<X_1\leq v,\ldots,u<X_n\leq v) \\ &= F(v)^n-(F(v)-F(u))^n. \end{align} $$ But $$F_V(v)=P(V\leq v)=P(X_1\leq v,\ldots,X_n\leq v)=P(X_1\leq v)\cdots P(X_n\leq v)=F(v)^n.$$ What is wrong with these computations?


Search value in all tables content - oracle

I want to search a specific word in all tables content. I mean in all column contents of all tables.   I don't mean in all tables names or all column names.   Thanks.


Indicate the type/colour of badge awarded in the top bar achievements dropdown

Currently with the achievements dropdown for rep changes you see the site icon, then rep change, then a link, but when earning a badge there is a gap where the rep is for reputation achievements.  I think the empty space (where the mouse cursor is in the pic below) should have the badge icon there, possibly linking to the badge in question.


This is just... wrong. Chrome latest, just started now.  It only seems to be happening on SO, I checked several other SE sites.


fstab mount, boot stuck on "A start job is running for dev-disk-by\..."

I am running debian 8.1 and working on this for hours now! I try to auto mount seagate and medion on boot if they are plugged in, but if the server is booting without one of these LABELs it stucks here for 1:30min and boots into maintainace mode:  Give root password for maintenace (or type Control-D to continue):   I just want to mount my usb devices if they are present.. : /    /etc/fstab:  # /etc/fstab: static file system information.  #FIXED #<file system>                             <mount point>   <type>   <options>           <dump>   <pass> UUID=f243951c-f61c-4af7-88c5-79ba0a33caf8  /               ext4     errors=remount-ro   0        1 UUID=28737539-1569-4db7-9ea3-d74473502f39  none            swap     sw                  0        0  #REMOVABLE #<file system>   <mount point>   <type>    <options>                    <dump>   <pass> #LABEL=medion     /mnt/medion     ntfs-3g   rw,noauto,nobootwait,nofail  0        2 LABEL=seagate    /mnt/seagate    ntfs-3g   rw,nobootwait,nofail         0        2


How do i approach file encryption using encrypt-then-mac?

I'm programming a cryptographic application that encrypts files, locked with the password the user supplies. It's not intended to be used in production. It's a project for me to learn more about encryption.  I have programmed the encryption part already, it's in C# and i'm using CBC as cipher mode.  I want to add authentication to my encryption and i plan on doing that by using CBC + HMAC(SHA256). I know that i have to HMAC the IV + Ciphertext. And yes i know BouncyCastle has an API that offers GCM(which is probably preferred over using CBC + HMAC), but the API's barely have any documentation and i read that CBC + HMAC is probably just as secure if done correctly. KeePass() uses it too.  However i'm not sure how to go about generating keys for the HMAC and the encryption itself. If i understand correctly it's always best-practice to use different keys for different operations (and rightly so). I'm currently encrypting the file content with a key that is generated by deriving a 256 bit key with the PKBDF2 algorithm(which takes a salt and does 10.000 iterations), but i need a key for the HMAC too. What is the best way to go about generating a key?  If you notice any mistakes and/or misconceptions in this post please tell me.


I know that every adiabatic reversible process is an isentropic process.  Can a process be isentropic but still not reversible adiabatic?  Please provide me some examples.


I play Terraria on mobile and I'm getting bored. I would like to get to hard mode. I have tried 4 times without succes. The final is getting super close, but I keep getting killed by a hell bat. Is there a way to get rid of other mobs or any other overall advice?


I don't have .bash_profile or .bashrc files and I am definitely using the bash shell. I am using Mac OS X 10.11.1 El Capitan.  How do I permanently modify my $PATH to cut down the default values Apple ships?


Error when comparing a string in if-else statement java

I want to make a simple console calculator in Java and I want to ask the user that which operation do you want to perform here is my code to get a better understanding. import java.util.*; public class Calculator {     public static Integer add(Integer numb1 ,Integer numb2)      {         Integer result = numb1 + numb2;         return result;     }     public static void main(String[] args)      {         Scanner sc = new Scanner(System.in);         System.out.print("Which Operation do you want to perform : ");         String operate = sc.next();         if(operate == "add")         {             System.out.print("Enter 1st no.");             Integer fnumb = sc.nextInt();             System.out.print("Enter 2nd no.");             Integer snumb = sc.nextInt();             result = add(fnumb, snumb);             System.out.println(result);         }         sc.close();     }    }  I think the code is right but the lines under the if condition never executes please help. And please don't write that you don't need to use if-else because you only have 1 method that is - add() because I will add more methods like subtract and multiply


Problem  A group of $n~(1 \leq n \leq 30)$ bandits hid their stolen treasure in a room.  The treasure needs to be locked away.  The bandits want to ensure that at least $k~(1 \leq k \leq n)$ of the bandits must agree in order to retrieve the treasure.  They have decided to place multiple locks on the door such that the door can be opened if and only if all the locks are opened.  Each lock may have up to n keys, distributed to a subset of the bandits.  A group of bandits can open a particular lock if and only if someone in the group has a key to that lock.  Given $n$ and $k$, how many locks are needed such that if the keys to the locks are distributed to the bandits properly, then every group of bandits of at least size $n$ can open all the locks, and no smaller group of bandits can open all the locks?  For example, if $n=3$ and $k=2$, only 3 locks are needed - keys to lock 1 can be given to bandits 1 and 2, keys to lock 2 can be given to bandits 1 and 3, and keys to lock 3 can be given to bandits 2 and 3.  No single bandit can open all the locks, but any group of 2 bandits can open all the locks.  My thoughts  At first glance, I thought it was just a simple combinations problem ($nCr$), and the provided test cases confirmed my suspicions: when $n=3$ and $k=2$, $\binom{3}{2}=3$.  Likewise, when $n=5$ and $k=3$, $\binom{5}{3}=10$.  However, two cases where this doesn't work are where $n=2$ and $k=1$ and $n=5$, $k=4$ (it gives $2$ and $5$, respectively, when the correct answer according to the judging data should be $1$ and $10$).  Next, I bothered a colleague who's a math major, and he briefly glanced at it and suggested it might be a hypergeometric distribution problem.  However, if this is correct, I'm having trouble wrapping my head around it - all the examples I can find have 2 distinct categories, e.g. red and green marbles being drawn from an urn, and I don't see that here.  An example in the terms of this problem would be extremely helpful.  If this isn't correct, where do I go from here?  I've been spinning my wheels on it for quite a while.  Background  This is for homework for a CS class (I'm a CS major with 2 semesters of calc plus discrete).  I'd like to be able to understand the math behind it, because once I can understand it, I can program it.  This problem originally came from an ACM ICPC regional contest this year, but my professor has made it into a challenge homework problem.


In array there are four element so it size should be 4bit*4 = 16. (An int data type take 4 bit in my system to store the value.) But when i ran this code i only got 8 bit as the size of dynamicArray.  #include <stdio.h> #include <stdlib.h>  int main(void) {      //Dynamic arrays save memory by creating a pointer that stores     //the beginning of the array     int *dynamicArray = malloc(20 * sizeof(int));     *dynamicArray = 10;     printf("Address %x stores value %d\n", dynamicArray, *dynamicArray);      dynamicArray[1] = 20;     printf("dynamicArray[1] stores value %d\n", dynamicArray[1]);     dynamicArray[2] = 45;     printf("dynamicArray[2] stores value %d\n", dynamicArray[2]);     dynamicArray[3] = 34;     printf("dynamicArray[3] stores value %d\n", dynamicArray[3]);     printf("The size of dynamicArray is %d\n", sizeof(dynamicArray));      // Release unused memory:     free(dynamicArray);      return EXIT_SUCCESS; }   Here is the image of output.    Also suggest me website for C to check the in-built function properties or to know about them more. Thank you.


Is C++ pass by reference internally pass by value

The pass by reference mechanism provided by c++ internally again uses pointers and is just pass by value or is it something different ?


Why is the Converse to Lagrange's Theorem False?

Can somebody explain me how is the converse of the  Lagrange's theorem  false by saying that $A_4$ (alternating group) doesn't contain any subgroup of order $6$?


I've just bought a new Toshiba laptop, on which Windows 8 is preinstalled. I've installed Ubuntu Gnome 13.10 and GRUB2 correctly detects Ubuntu and Windows. But the strange problem is that when I try to boot Windows 8, it appears the following error:  /EndEntire file path:/ACPI(a0341d0,0)/PCI(2,1f)/UnknwnMessaging(12)/HD(2,200800,82000,a8d996409dcfe211,a8,59)/File(\EFI|Microsoft\Boot)/File(bootmgfw.efi)/EndEntire error: cannot load image.   I've tried to solve using boot-repair, using the auto-correction. But never has changed. Here is the log generated by boot-repair:   How can I fix this?


I was overloaded the two operators: operator<< and operator++  operator<<  ArithmeticSequence & ArithmeticSequence::operator++() {     this->lastElement += goToNext;     this->sum += lastElement;      return *this; }   operator++  ostream & operator<<(ostream & out, const ArithmeticSequence as) {     out << as.sum;     return out; }   now the main is:  ArithmeticSequence AS(1.3, 2.5); cout << "++AS sum: " << ++AS << " ++AS sum: " << ++AS << endl;   output:  ++AS sum: 20.2 ++AS sum: 11.4    the correct output need to be:  ++AS sum: 11.4 ++AS sum: 20.2   why the output is revers?


Is it possible to integrate Django web site and PHP forum by some apache directive in httpd.conf file? For example:  <VirtualHost *:80> ServerName myserver DocumentRoot home/myserver/www/ WSGIScriptAlias / /home/myserver/www/mywebsite/mywebsite/wsgi.py <Directory "home/myserver/www/mywebsite">     Order allow,deny     Allow from all </Directory> Alias /forum/ /home/myserver/www/mywebsite/forum/ <Directory /home/myserver/www/mywebsite/forum>     *tell apache it's PHP* </Directory>  I've seen this question, but no one said anything about directives..


Does Ubuntu work on a Raspberry Pi Zero?

A new super-cheap version of the Raspberry Pi . I'd like to stuff these all over my house doing cool nonsense.    My question is, will I be able to use Ubuntu on them?


Programatically determine the size of an array of strings

Is there a way in C to know how many values are in an array initialized like this?  char *string_array[] = {"one", "two", "three"};   Obviously there are three strings in the array but how can I determine the size at run time?


Does rsync verify files copied between two local drives?

I want to make a fresh new copy of a large number of files from one local drive to another.  I've read that rsync does a checksum comparison of files when sending them to a remote machine over a network.   Will rsync make the comparison when copying the files between two local drives? If it does do a verification - is it a safe bet? Or is it better to do a byte by byte comparison?


Trying to delete a zone file from a name server (remote) from a local machine (connecting to the remote server with a key pairing). Script on the name server is below (remzone) which is executable. #!/bin/bash sed -i '/$1/,+4d' /etc/named.conf rm -f /var/named/slaves/$1.db rndc reload echo "$1"  The local command I am running is..... ssh root@server '~/remzone domain.com'  When I run the command locally, the following output is provided. me@Main:~$ ssh root@server '~/remzone domain.com' server reload successful domain.com  When executing the command locally, the domain.com.db is removed from /var/named but it does not remove the matching line (+4 lines) from /etc/named.conf. Zone    "domain.com" IN {         type slave;         masters {XXX.XXX.XXX.XXX;};         file "slaves/domain.com.db"; };  When I run sed -i '/domain.com/,+4d' /etc/named.conf on the nameserver directly, it deletes the zone file correctly from the /etc/named.conf file. Any Ideas?


There are n chairs in a row. In how many ways can a teacher sit k students on these chairs so that no 2 students sit next to each other (and obviously no 2 students sit on 1 chair)?  I was thinking about inclusion-exclusion, that each student will sit next to each other, however it isn't good enough since there could be more chairs than students.  Basically currently I have no idea how to solve it.


As the tittle says, I've tried to render my model for quite a long time. I read a post here but I couldn't solve anything, this is my current configuration for lamp/camera  I have already tried every solution in threads here, doesnt solve anything, I've actived nodes but still doesnt show up.  I dunno if it can be because the size of the camera and the lamp (The object is like 40cmx25cmx7,5cm and the lamp/camera is default size)      EDIT: I've tried by recommendation of another user to delete and add another camera, the problem still persists


How do i protect my game assets as an individual?

For my first games, they will be well made, complete, but extremely simple, while i father enough funds to actually fund a game company.  But because I plan on releasing quality content under {insert my name here} Studio (trademark)(c)  and of course all of my games will be superseded by a (c), despite the fact I haven't even registered anything.  But the real question is, what steps do I need to take to make sure my content does not get stolen while im financially stable enough to file all the paperwork needed to maintain proper copyrights?  I'd also like to release a major title, but I'm scared to, because I know someone is going to try and steal it.


Keep running program requiring X server after logging off of ssh session

I have a python script that periodically generates a png image, and puts it on a server that I can access through a browser. The image displays the progress of a job I am running on the server. I'm using matplotlib to generate the images.  The python script goes to sleep after generating each image. After an hour, it wakes up, generates a new image, and then goes back to sleep.  I start the script over an ssh session. When I log off, the script gets killed. I've read the other threads covering this problem, but the proposed solutions do not work. The script is killed after I log off, even if I run it with  nohup script.py &> job-monitor.log &   or if I run it like this  script.py [Ctrl-Z] disown -h %1 bg 1   The strange thing is, when I log off and log back in, the script is no longer running, and job-monitor.log is empty.  What could be happening, and how do I get the script to continue running after I log off?  Additional information: I think the problem has to do with the plotting library I'm using, matplotlib. I think it may require an X session to produce a png, even though the graphic is just being saved to disk.


Is there a command to know whether my "/var/lib/dpkg/status" is fine? To be sure that there is nothing wrong in dpkg and its files

I ran different commands. Maybe I have also corrupted many things.  But I do not see any sort of error or crashes so far. So my main question is how do I know that my pc is healthy and there is nothing wrong in it?! I want to try all "Safe" commands that you guys probably know and see if something is wrong or not. Kind of like "Debugging my PC" as smooth as possible. Especially focusing on dpkg case. And other cases if you know.