"System" storage on macOS Sierra is 470GB!

My Mid 2012 MacBook Pro 13" says I suddenly ran out of Storage space.   My Mac barely has any data and my upgrade to Sierra was a clean install. Nothing was ported from previous backups.   If you see the image below, the "System" section in the left column says that it is consuming 466.82 GB. What I don't understand is why does my Mac require so much space? As far as I know, it should never increase 50 GB of space. Any help is appreciated.


What is the meaning of "[:-2]" in "header_text = f.read(header_text_size)[:-2].decode('utf-16').encode('utf-8') "

header_text = f.read(header_text_size)[:-2].decode('utf-16').encode('utf-8')   What is the meaning of [:-2] in this Python code? I want to translate this into Java, and I need to know what it does.


Type of vs Types of, kind of vs kinds of

I found a line on a page where I got, What type of books do you need?  I think what types or kinds of books do you need? is more appropriate. I would like to know the real use of them. If I am not wrong type of follows countable one and noun has to be singular. On the other hand types of follow uncountable one and noun has to be plural. Could someone help me out with this issue? Please give some example also.


Custom numeric format string to always display the sign

Is there any way I can specify a standard or custom numeric format string to always output the sign, be it +ve or -ve (although what it should do for zero, I'm not sure!)


Every number has the factors of $1$, itself, $-1$, and the negative version of itself (itself multiplied by $-1$).  So let's take for example $5$, it has the factors:     $ 1$   $ 5$   $-1$   $-5$   Since the definition of a prime number is a number with the factors 1 and itself, should this not mean that all numbers are composite?


jQuery - select the associated label element of a input field

I have a set of input fields, some of them have labels associated, some not:  <label for="bla">bla</label> <input type="text" id="bla" />  <label for="foo">bla <input type="checkbox" id="foo" /> </label>  <input ... />   so, how can I select the associated label for each input, if it exists?


Testing the goodness of fit for a Poisson model

I need help in calculating the goodness of fit for a Poisson model. The online literature on it is quite scarce, so if you have any useful articles and links I would appreciate it very much.  Here is how the table looks like from SPSS. The outcome variable is a count of patents a company has.


What is the official rule when mentioning a city/ state in a sentence?  I always thought there was a requirement for a comma between the city and state, however is there also supposed to be a comma afterwards?     Tim also enjoys football games, jumping on his motorcycle and being a   guide for the Fredrick, Alabama, restaurant scene.   I personally think it looks clunky, however I'm told that it is opinionated and that the above is correct.  Should the sentence be written like this?     Tim also enjoys football games, jumping on his motorcycle and being a   guide for the Fredrick, Alabama restaurant scene.


How to distinguish between gold, silver, and bronze tag badges on SEDE?

How can I distinguish between the levels of , say , querying ? For example, Mr. Jon Skeet has all the gold, silver and bronze badges for LINQ, so the query select * from Badges b with (nolock) where     b.Name = 'linq' and b.UserId = 22656  returns 3, with no distinction between them. Is it possible to include such information into the dump, for example, keep a unique badge ID (40 for the gold  badge)?


Should I publish work from my undergrad now that I am in graduate school and no longer working in the same field?

During my undergrad (past 3 years) I worked in a niche ecology lab and during the time generated some data. The work I did was not exactly groundbreaking but I think it was solid publishable work and could find a home in a decent journal.   My PI is encouraging me to write up my work and submit it for publication in the next few months but I have just started graduate school and am working in an entirely different field (Biophysics with a sprinkle of cell biology).   Considering that I expect writing up the work for publication will be a significant undertaking (seeing how it would be my first time writing a paper for publication), and the disparity between the subject of the paper and my current/future research, would it be worth the time commitment to follow my PIs advice and write the paper? Would there be any real benefit for my career in a different field if this work does get published?


Can not unlock my Android device as have no internet connection?

I have an Android device which is running Android 4.0.3 (or something like that).  My little brother decided to try and guess my lock screen pattern the other day, and ended up locking me out.   I have since been unable to log back in to the tablet using my Google Account details. I provided the correct login details, however it says they are incorrect. Could this be connected to the fact I have no internet connection?  I have no internet connection as the device is WiFi only, and the WiFi is currently turned off. I cannot turn it on, as I am locked out.  How can I log back into my tablet without wiping the user data?


Clearly, uncountable cardinals exist. How do we know that $\aleph_1$ is the smallest one? Is there a proof that there is no cardinal strictly between $\aleph_0$ and $\aleph_1$.


Does IEEE membership have any value whatsoever on the CV?

Some CS veterans would probably shoot me on sight for questioning its value, but let's face it, you are a member of IEEE if you're paying them a fee every year, and I don't think there's anything else keeping you from entering if you're in CS/EE. I see every single professor writing it on his CV though, and it is beginning to look like a must-have.  Agreed, you get some (limited) access to papers from their library, and a discount for conferences and the rest of the library, but as a student I can't afford to skip classes to go to conferences (and often I can't afford the travel costs either), and I have few things pressuring me to read papers, if any. In fact I haven't come across a subject with so little material on it with public access that I felt I needed access to other papers.  I'm not denying the existence of people that actually use the papers they have access to, but I am confident that a survey would reveal that not even a quarter of the members access the libraries.  To sum up my points:   It only shows that you pay a fee every year Probably without using anything of what you get for that fee It just adds a line to your CV that doesn't really say anything about you.   So does it have any value? Do people notice this? Is it worth renting a title and nothing else?  Concerning whether or not it is a duplicate of :  That question assumes membership is already active and asks if it is worth mentioning it, however it costs nothing to mention something you already have so the parameters are significantly different. This question questions if it is even worth obtaining the membership, essentially also asking if this (or any) title is worth paying for, given that many others already do so.  Even though some of the answers do make mention of whether it holds any value to those who answered, they do not address if university staff or recruiters pay attention to this, or even how it affects them. One could even see it as renting a title to compensate for lack of other things to write on the resume.


Are there any repercussions to killing Policemen?

If I kill all the policemen in the police station with the alarm activated will it prevent me from continuing the game?   What about other repercussions?


Is it possible to "upgrade" from a 32bit to a 64bit installation?

As per title, I wish to know if I can, after a successful 32bit setup and consequent software installations, update to a 64bit version.  I know how to partition (actually one of the solutions is to set /, /etc, /home, /var/www, and /opt as separate partitions) and I know that a clean install is way better than a dirty one, yet I would like to know if/how it's possible to do that.


Help me check the directory that my shell is currently in

I have this question from an assignment, but the school's resources are inaccessible at the moment, so I need some help. Google is not very helpful for this.  I have only just installed ubuntu, so this is probably basic to some, but not me im afraid. Does anyone know how to 'Check the directory that your shell is currently in'? My assumptions are that terminal is considered my shell, and that I should look for the program file. I have looked around the usr subdirectories using ls. I can't find terminal listed there. If there is a better way to interpret the question I would like to hear about it. :)


why string multiplied by and integer and variable multiplied by integer is not same?

Suppose on the following example:  a='a'   while multiplying by an integer both a*2 and 'a' *2 yields same result  >>a*2 'aa' >>'a' *2  'aa'   however this does not hold same for comparing:  >>a*2 is 'aa' False >>'a' * 2 is 'aa' True >> a*2 is 'a' *2 False


How to access FTP with read AND write access in finder?

I just read that finder has purposely restricted access when it comes to connecting to FTP sites. Not sure how any apple exec could possibly think this is acceptable. Simply put, I need to find a way to force finder to allow write access for a FTP server. Transmit no longer provides this functionality. Im not looking for any third party software. There should be a terminal command that forces finder to allow access?


In JavaScript I encode part of uri:  var imageName = "test space in name of image.jpg" var sentWithAjaxVariable = encodeURIComponent(imageName); //sentWithAjaxVariable in console is "test%20space%20in%20name%20of%20image.jpeg"   On server side, in handler I want to decode this variable like this:  var imageName = context.Request.Params["sentWithAjaxVariable"]; var decodedImageName = context.Server.UrlDecode(imageName); //decodedImageName in watch => "test%20space%20in%20name%20of%20image.jpeg"   why not decode?


Drop to root shell (security vulnerability?)

I've known about the ability to drop to a root shell for quite a while. You just hold shift and select (recovery mode) from the list of kernels presented.  I would mess up an install, then drop to root shell and be confused as to how that's useful when it's read only and I can't actually fix anything. Recently I discovered  post from 2012, showing how you can run:  mount -o remount,rw /   Which will remount root in read-write mode. I was happy that now I can edit things, and fix whatever config file I shouldn't have changed in whatever ways, but now I'm root, with access to everything root can access?   Pretty cool I thought, unless I'm somebody who doesn't own my computer. I can read all of the password containing files with permissions of root:root 400. I can modify config files and cause all kinds of mayhem.  So the question is, if someone has physical access to my machine, is my system vulnerable to their knowledge of this? Is there something I'm missing?  Is full disk encryption the only way to go?


I have a strange problem, when I'm inserting data into the database.  When I'm passing the value from form field in English, everything works as expected (the value is inserted). However, when I pass the value in another language (e.g. Russian), the value inserts, but it is empty in database table. Not null, just an empty value.  I am using the . I have tried to set the proper charset with mysql_query("SET NAMES utf8");, but it doesn't work, and the table data in the database is set as utf8 and utf8_general_ci.  Anybody knows how to solve this issue?  Hey guys, I just found out that the problem in my Controller, the incoming parameters are in wrong charset. Here is the output result: ��� ������� Does anybody know how to set charset in Kohana controller?


Leibniz Rule for Covariant Derivative Question

I am watching a series of lectures about General relativity by F. Schuller. In the Lecture 7 - Connections (  ) he gives the properties for a covariant derivative respect to a vector field. But instead of the Leibniz rule: $$\nabla_v(T\otimes S)=(\nabla_v T)\otimes S + S \otimes (\nabla_vS)$$ he gives this rule: $${ \nabla_v}(T(w,Y)) =        ({ \nabla_v}T)(w,Y)+T({ \nabla_v}w,Y)+T(w,{ \nabla_v}y)$$ And he claims is equivalent to the Leibniz rule,  but I cannot even derive this rule from the Leibniz rule. Some help please??


Impose a re-entry delay on users kicked out of a chat room

Currently, moderators can kick users out of a room.  I've done this to two users now, and they just come right back into the room.  I conclude that it's not effective for its presumed purpose (slowing down trolls or other troublemakers, on a room-specific basis).  I propose that a delay be imposed on users after getting kicked, before they can re-enter a room.  It wouldn't have to be a large delay; 15 minutes at the most.  This would satisfy those folks who need a way to slow down users that are disruptive, without having to resort to long lists of users with write access and use of "gallery mode."  It's also a less blunt instrument than suspending users from chat.  In addition, if this isn't already a feature request,  I think room owners should be able to kick users.


Conservation of momentum involved in explosions

Bomb explosion is an example for conservation of momentum.Initial momentum of the bomb or the system is said to be equal to final momentum of the system.How is this possible?The individual particles are in motion after the explosion,right?Then how is final momentum and initial momentum the same.I can't visualise.Help me visualise. ;)  If for example for easy method of understanding,a bomb consisted of three identical particles.Initial momentum is zero.But how can final momentum be zero.Arent the three particles move in the x,y,z plane with different velocities in different directions?


does inverse of continuous function is also continuous?

Suppose that $f:R\rightarrow R $ is continuous and does have an inverse function. How can I prove that $f^{-1}$ is also continuous?


It is fairly easy to show that harmonic functions satisfy the mean value property, but it seems harder to show the converse. I've seen the following theorem without proof:     If $u \in C(\Omega)$ satisfies $$u(z) = \frac{1}{|\partial  B_r(z)|}\int_{\partial B_r(z)} u\,dS$$ for all $z \in \Omega$ and   $B_r(z) \subset \Omega$, then $u \in C^\infty$ and $u$ is harmonic on   $\Omega$.   When I try to prove it myself, I got stuck. Could anyone kindly show me how to prove this? Thanks.


Render Shadeless Image as Background with Cycles in Blender 2.9

How can I make a png image with an alpha mask shadless, meaning the image, which I want to use it as a background, won't be affected (washed out) by the lights in the scene? I am currently using Blender 2.91. From tutorials, in older version of Blender, there was a shadless option somewhere in the material properties but I can not find it in my current version of Blender. Simple example is provided in the screenshot below. Regards


Is there any way to encrypt the huge amount of data using RSA?  I was supposed it is possible but when I read some articles what I saw is that, this is bad practice or they say can only encrypt bit length/8 characters only i.e. if I use 1024 then I could able to encrypt 1024/8 = 128 characters and so on. So if I want to encrypt more data (characters) then my RSA bit length is to be increased.


How can I prove $\frac {d}{dx} {x^n} = n x^{n-1}$ for $ n \in \Bbb R$ without circular reasoning?

I just cannot prove that $$\frac {d}{dx} {x^n} = n x^{n-1}$$ for $ n  \in \Bbb R$.  For $n \in \Bbb{N}$, I can use the definition of a derivative :  $$\frac {d}{dx}x^n = \lim_{h \rightarrow 0} \frac{(x+h)^n - x^n}{h}$$  Now applying "Binomial Expansion" for $\displaystyle (x+h)^n=\sum_{i=0}^{n}{n \choose i }x^{n-i}h^i$ and expanding, the $x^n$ term in the numerator cancels out and the $h$ from denominator divides the entire remaining expression . Taking limit $h$ tending to $0$ gives the required result.  I have been taught that the derivative result holds for all real $n$. But I am not aware of any "formula" which can allow me to expand a binomial expression with real index. I do know about the Taylor Expansion, but if I remember correctly, it utilises the very derivative that I am trying to find.  How can I proceed ?


I overheard my manager asking "What are you up to?"  What does that idiom mean? Is it an informal/negative way of asking??


Group homomorphisms and which of the following statements are true (NBHM-$2014$)

Let $G$ be a finite group of order $n\ge2$. Which of the following statements are true? a. There always exists an injective homomorphism from $G$ into $S_n$. b. There always exists an injective homomorphism from $G$ into $S_m$ for some $m\lt n$. c. There always exists an injective homomorphism from $G$ into $GL_n(R)$.  I think b. is right (don't know how to prove though). I also think that c. is false. But not sure.


Incorrect Disk space usage in Linux server

I can see the used disk quota on server is 81G for partition /dev/sda3 mounted to '/' as follows.  Filesystem      Size  Used Avail Use% Mounted on /dev/sda3       106G   81G   20G  81% / tmpfs           1.9G     0  1.9G   0% /dev/shm /dev/sda1       477M   52M  400M  12% /boot tmpfs           1.0G     0  1.0G   0% /var/lib/mysqltmp /usr/tmpDSK     4.0G  183M  3.6G   5% /tmp   But when Iam checking with the '/' directory by executing du -sh command it is taking only 17G of disk space, can any one advice where this remaining space is utilized, any advice ? Iam using CentOS release 6.7 (Final)


Can a USB 2.0 cable support USB 3.0 charging?

I have some USB 3.0 ports on my motherboard which can deliver up to 900 mA of current I believe.  If I plug in a USB 2.0 cable, I can still get up to 900 mA right? I have some devices that uses USB charging and outputs from 1A to 2A but I'm not sure if the cable provided is a factor or not since I'm just using a generic USB cable for this.


This put in the context of a age problem will be:     the product of my age seven years ago and seven years later is some perfect square   Since this is a age problem that perfect square has to be between 1 and 100. I've try every factor of number between 1 and 100 inclusive, and found none that matches.  Can there be another way besides trial and error?


Does SEO ranking based on domain apply to domains with forwarding?

Lets say I have a site at "myrandomdomain.com". I want to target a keyword "my keyword" and so I buy "mykeyword.com". Can I still have the keyword benefits of having mykeyword.com when it just forwards to myrandomdomain.com? The domain would not be masked. My guess would have been no but SEO Moz seems a bit unclear about it:     A 301 redirect is a permanent redirect which passes between 90-99% of   link juice (ranking power) to the redirected page.   I'd just like to make sure before I switch my site over. If it would have the same effect to forward it I'll just do that.


Power off an USB device in software on Windows

I would like to power cycle an USB device through software on Windows.  I am doing development on a small USB power microcontroller. This chip will revert to native behavior on a power cycle and allow a code download.  Since my code will crash the device when things go wrong -- making it ignore all USB commands -- I have to physically unplug the device from the system.    I want to do development remotely, and not have to be physically present.     So far I have tried using "devcon" to disable portions of the USB stack. While this takes the hubs into D3 (should be powered off!), there is still power being supplied to the device.    Are there any preexisting solutions or SetupAPI tricks that might help?


Is "walk" in this sentence correct? Could it be replaced with walks or will walk?

Almost every creature you see, besides the elephants, walk on two legs, like me.


Assuming no editing, what's the difference between in-camera jpegs and lightroom jpegs?

I have a Canon 6D. I usually shoot RAW + JPEG. I shoot RAW so I have the option to edit, but I don't actually edit most of my pictures.  I've noticed that if I just import into Lightroom and export JPEG's at full resolution and where quality is roughly 80, the file ends up being about the same size as the full res JPEG version from the camera.  What's the difference (other than time taken) between these two? Is there a (practical) difference?


When asking someone questions about the future, would you ask Will you not? or Will not (won't) you?  For example, of     1. Will you not go to school today?    2. Will not you go to school today?    3. Won't you go to school today?  which are grammatically correct?  It's very confusing to me.


I have a 5v dc supply generated from voltage divider and this 5v is used to drive L293d.  But the problem is as soon as 5v supply is given to L293d the voltage drops to less than 2v.  what could be the problem??


Atmospheric pressure experiment using a cup with a fluid to hold a glass plate

When I was in high school, my teacher did an experiment to show the power of atmospheric pressure.  Experiment: Prepare a glass bottle, fill with water, put a glass plate on the bottle, make sure there is no air in the bottle, just water. Hold the glass bottle and plate, and invert them. Slowly, release the hand which hold the plate. Because the atmospheric pressure, the glass plate will not fall down.    Question 1: As we know, if we didn't put water into the glass bottle, just air in the glass bottle the glass plate will fall down. So, If we use other liquid instead of water, this liquid has smaller density than water, like alcohol, the plate will not fall down. But, if we continue to chose the smaller density liquid until the liquid has density like air the plate will fall down. So, if there is a threshold density of liquid make the plate between falling  down and not falling down?  Question 2: If we put the bottle and plate into water slowly, when the plate and part of bottle are in the water but part of the bottle still above the water, will the plate fall down?  Question 3: Continuing question 2, when both bottle and plate are in the water I know the plate will fall down. So, how does the pressure of water and atmosphere change?  Is there a good description of this phenomena?  Why does the trick continue to work with lower density fluids and why does placing the plate in the water cause it to fall?


pointer and then object after new operator in C++

I got this snippet of code and if you see in the return statement of NewNode after new in bracket i have buff. What does this buff in bracket is doing in new statement.   struct Node     { int key; }      Node* NewNode(int key)     {char *buff = allocate();     ...     return new (buff) Node(key)}


Randomly choose a name from an array (values at beginning of array more likely)

So I have a list of the top 100 boys names in Ireland:  Here's my PHP:  <?php $top100irishNames = <<<END Jack James Daniel Sean Conor Adam Harry Ryan Dylan Michael Luke Charlie Liam Oisin Cian Jamie Thomas Alex Noah Darragh Patrick Aaron Cillian Matthew John Nathan David Fionn Evan Ethan Jake Kyle Rian Ben Max Eoin Tadhg Finn Callum Samuel Joshua Rory Jayden Joseph Tyler Sam Shane Mark Robert Aidan William Ronan Eoghan Alexander Leon Cathal Mason Tom Oliver Andrew Oscar Ciaran Bobby Jacob Senan Rhys Scott Benjamin Cormac Kevin Lucas Alan Donnacha Jakub Christopher Filip Killian Josh Alfie Tommy Ruairi Odhran Oran Leo Isaac Dara Jason Zach Martin Peter Brian Danny Niall Tomas Edward Stephen Logan Kacper Anthony Billy END;  $top100irishNames_arr=preg_split("/\n/",$top100irishNames); for($i=0;$i<25;$i++){     echo getRandomWeightedElement($top100irishNames_arr)."\n"; }   function getRandomWeightedElement($arr) {     $rand = mt_rand(1, (int) sizeof($arr));      for ($i=0;$i<sizeof($arr);$i++) {         $rand -= $i;         if ($rand <= 0) {             return $arr[$i];         }     } }  ?>   Jack, James, Daniel, Sean, etc. should output a lot...  But here's some random output:  Ryan Cian Luke Charlie Harry Luke Harry Charlie Oisin Ryan Luke Luke Michael Liam Liam Adam Ryan Oisin Conor Oisin Liam Oisin Daniel Adam Oisin   I don't see any Jack/James/etc.?  I'm trying to have the sampler output the names at the beginning of the array most often, and the names at the end of the array least often.


cat command doesn't show the lines of the text

i am trying to read an odt file from terminal. When i type cat myfile.odt it shows me an image like this


Proof explanation on a group of order $595$ having a normal Sylow $17$-subgroup.

Prove that a group of order 595 has a normal Sylow 17-subgroup.  The proof is as follows:     By Sylow, $n_{17} = 1$ or $35$. Assume $n_{17} = 35$. Then the union of the Sylow   $17$-subgroups has $561$ elements. By Sylow, $n_5 = 1$. Thus, we may form a   cyclic subgroup of order $85$ (from a previous theorem) But then there are $64$ elements of order $85$. This gives too many elements.   My question is:  Where does this $64$ come from?


How does one find a decreasing sequence of closed balls ( not necessarily concentric) in a complete metric space whose intersection is empty?


What motion can emerge in a still universe?

I consider a very large non homogeneous cloud of dust in isolation. No external gravitational interactions. It is initially completely still and start collapsing under the its own gravity.  Can the separate gravitational collapse of denser subparts, interacting with the rest of the cloud, induce spinning motion in some of these subparts?  To avoid consideration of limit conditions, the cloud may be considered infinite.  I am interested in an answer primarily in Newtonian mechanics. But if relativity can change the answer, that is interesting too, as a complement.  The same goes for quantum mechanics (though I doubt it is compatible with my stillness hypothesis). BUT, my primary interest is pure Newtonian mechanics.  I did some research on the site, and this question has not been asked or answered previously with the explicit precondition of initial stillness of everything, i.e. lack of any relative motion between any two parts of any size.  My prime motivation for asking it is that all questions regarding motion and (angular) momentum seems to be answered somewhat tautogically by: there is this motion because there is that motion, exchanging this for that here and there.  Of course. collapse does create motion. So the question is really about spinning motion and orbital motion.  My own belief, though I do not have the math to prove it formally, is that lack of homogeneity is enough to cause the emergence of angular momentum in equal opposite amount in different parts of the cloud, so that the total angular momentum remains null.


Splitting a range into an even number of n groups

I'm trying to setup threads with an even number of API pages to query for each thread. Example below has 9 pages that I want to call in total, and I want to split into 2 threads: first thread would ideally query pages 1-4, and the second thread would query pages 5-9. But I'm having some trouble getting it to evenly and properly distribute. The following works for threads = 2 and an even number of pages, but not for odd number of pages because I call the variables as range(page_start, page_end) and want the 9th page: import math pages = 9 page_end = 1 threads = 2  for thread in range(1,1 + threads):     page_start = page_end     page_end = page_start + math.floor(pages/threads)      print(page_start, page_end)  # Output is  # 1 5 # 5 9  # when it should be the following  # 1 5 # 5 10  Every time I fix this, it breaks when pages is set to an even number.


Is there any evidence of black holes existing?

Yes, I am aware of observations of "massive objects", for example near the center of the galaxy. But is there any evidence that the object in question is a black hole, with all its commonly attributed properties? Or are black holes just an unconfirmed artifact of general relativity, i.e. something that is an abstract mathematical concept and not a real object?  EDIT: That is not an answer to my question. I did not ask about means of detecting them, I am aware of those means. I'm interested if there's anything suggesting that the properties commonly attributed to black holes, other than large mass, have anything to do with reality, or are completely abstract and deduced from math.


Simple way to find determinant of a given matrix

Consider the $(m-1)\times (m-1)$ matrix $M$ shown below.   $$ M=   \left[ {\begin{array}{cc}    1 & 1/2 & 1/2 & \ldots & 1/2\\    1/2 & 1 & 1/2 & \ldots & 1/2\\ \vdots \\ 1/2 & 1/2 & 1/2 & \dots & 1   \end{array} } \right]$$  I would like to show that $\det (M)=\frac{m}{2^{m-1}}$. I have tried induction, but the computation gets rather messy. When $m=2$, $\det(M)=1=2/2$, and when $m=2$, $\det(M)=1-1/2^2=3/2^2$.   I know some people are very good at seeing tricks to compute the determinant of a matrix like this without induction. Any ideas?  Thanks!


Question of size in double slit experiment

I have a few questions about double slit experiment.   In order to get an interference pattern with electromagnetic waves, what is the relationship between widths and separation of slits with the wavelength of the wave? What about if we want to get an interference pattern for electrons? What is the wavelength of electrons when they behave as waves? What about bigger objects? I've read that the interference pattern has been reproduced with big molecules. Is there any theoretical or practical limit on the size of particles for which an interference pattern is possible? This is my main question.


Getting image dimensions without reading the entire file

Is there a cheap way to get the dimensions of an image (jpg, png, ...)? Preferably, I would like to achieve this using only the standard class library (because of hosting restrictions). I know that it should be relatively easy to read the image header and parse it myself, but it seems that something like this should be already there. Also, I’ve verified that the following piece of code reads the entire image (which I don’t want):  using System; using System.Drawing;  namespace Test {     class Program     {         static void Main(string[] args)         {             Image img = new Bitmap("test.png");             System.Console.WriteLine(img.Width + " x " + img.Height);         }     } }


Bonjour à tou.tes !  In my document (compiled with LuaLaTeX) the footnote counter restarts at 1 in each new chapter.  How do I do to number all footnotes continuously?  For example:  \documentclass[10pt,a4paper,openany,notitlepage]{book} \usepackage[bottom]{footmisc} \begin{document} Bonjour,  I'm trying\footnote{to use footnotes} hard ! \chapter{Chapter one} Here I am\footnote{out there} so lost with it ! This is not a footnote\footnote{yolo}. \chapter{Chapter 2} encore une\footnote{cirhose} \end{document}                       After compilation:


I have had trouble with sound (now fixed) since upgrading to 19.10, and in the middle of trying the common solutions, the Software Center "disappeared". I got aware of quite late, so I don't know what caused it.  Anyway, would you know how to reinstall it ? Trying sudo apt-get install software-center doesn't work.


An abstract noun that refers to the quality of accomplishing something first

I am looking for a noun that means firstness as exemplified in the following  Examples   Roger Bannister was the first person to run a mile in under four minutes.  Not many of us can achieve firstness in something.  Neil Armstrong exhibited firstness by being the first person on the moon.  Some people prefer to answer first in a quiz, even if they get the answer wrong. They prefer firstness over correctness.  I thought of primacy. However the dictionary meaning doesn't fit -- primacy refers to importance rather than temporal 'firstness'.  I specifically want it to mean that the person achieves or completes something sooner than anyone else. Not that they achieve it better or to more acclaim.  Question: What is a noun (or failing that a short phrase) that means 'firstness' and would fit into those sentences without changing any other words?


Are there any WYSIWYG LaTeX table editors that you recommend for creating LaTeX tables?


I just downloaded the ISO and i don't have any blank cd's to put it on, can i install from an external hard drive?


When developing urban planning documentation (f.e. a master plan of a territory) each scheme or plan must be collected in a file in .mxd format. Does QGIS software generate a .mxd file?


Moto G2 is not detecting in ubuntu 14.04

I am using ubuntu 14.04 . My Motorola Moto G is not detecting when i plug it using usb. Is it because of missing driver? How can i get drver for ubuntu?


Tightest convex set containing curves of length 1

What is the smallest (either in terms of perimeter or area) convex shape in $R^2$ such that all curves of length 1 are properly contained within it ? I'm thinking a right triangle with sides of $1/\sqrt(2)$, but I'm not sure how to reason about this rigorously. Any pointers would be appreciated.


Trying to Mask Text in Ai. It is not going well

When I follow the instructions in the Adobe tutorial the mask is created but the color is totally off. I am using a gold texture and the screenshot below is what I end up with.  here's what it looks like before the mask (box and text are grouped)    then here's what it looks like when I use the mask (first mage shows transparency palette and placed image outline)     it doesn't seem to matter if the text is white or black, if the texture is clipped or unclipped, masked or inverted. I am pulling my hair out. What am I doing wrong?


When making a pie, you almost always have to make holes in the dough with a fork. This is called docking.  What is the exact reason for doing this? Are there kinds of pastry (puff, short crust, flaky) where this isn't necessary? Do you only need to do it when blind-baking? When you're using baking weights, does it still make a difference?


Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("GMT")); java.util.Date fromDate = cal.getTime(); System.out.println(fromDate);   The above code doesn't print the date in GMT, but rather prints in the local timezone. How do I get a GMT equivalent date from the current date (assuming that the program can run in Japan or SFO)


I do not know how to solve the following:     Show that If $(b,c) = 1$, then $(a,bc) = (a,b)(a,c)$   Thanks.


Proving $\int\limits _0^\infty\frac {\sin^{2n+1}x}{x}dx=\frac 1 {4^n}\binom{2n}{n}\int_0^\infty \frac {\sin{x}}{x}dx$

The question is     Prove that for any $n\in\mathbb N$, $\int\limits _0^\infty\frac {\sin^{2n+1}x}{x}dx=\frac 1 {4^n}\binom{2n}{n}\int_0^\infty \frac {\sin{x}}{x}dx$   I don't have any ideas how to solve it and I'll be glad to get a hint.


Any difference between 'it is impossible' and 'it is not possible'?

I am working as software engineer.  I have to use sentences like 'it is impossible' or it is not possible' in many emails.  I want to know that both are same or some has more impossible look than other?


Is the maximum function of a continuous function continuous?

Suppose $f(x)$ is continuous on the closed interval $[a,b]$. Define $m(x)=\max_{a\leq s\leq x}\, f(s)$, $a\leq x\leq b$. Is $m(x)$ continuous necessarily? Thank you.


Google Drive Search resulted in two files of the same name, and same named folder, but one of them is shared, while to other one is not

Search resulted in two files of the same name, and same named folder, but they are physically two different folders & files.  One is shared, the other is private. I can only access the private file/folder by using search. Can't see/access it during regular traverse of the Google Drive folder (only access the shared one).


Is the Standard LaTeX Book class capable of a Novel's dimensions, and the front back matter?

Can the standard LaTeX “Book” class adjust to the paper size and structure of a Novel sized book?  It would be smaller than the standard dimensions that LaTeX seem to be setup for.  The LyX dialog box for adding a custom paper size keeps the [ok] button grayed out after I’ve made my adjustments.  Would that requires another package to support customization, or does it require an adjustment in the settings of MikeTeX first?     I’d like to customize the standard paper sizes used in Novels, for instance those that fit nicely on a bookshelf with other novels, something small but not tiny.  ()  The “12mo” paper size would be perfect; it’s an American Library Association standard size, also known as "Duodecimo" 17.5-20 cm (5” x 7-3/8”).  Is the standard LaTeX using Book Class capable enough for typesetting a novel in final form typesetting a page that would fit on those dimensions, even if I have to use 8.5 X 11 and trim it, with all the proper pieces (front matter, main matter, back matter) of a commonly published novel?     I’m not thinking of a submittal to an editor, and not a submittal to a publishing house that converts submittals using their own system, but rather something that could be used for direct printing from pdf?  LyX or another LaTeX front end seems like the perfect solution for a Fiction project if the default packages are all that’s necessary.  I suppose if it can handle a scientific textbook with tables, formula and diagrams, then it’s more than capable enough.  That’s why I’m thinking that I could just use the Standard LaTeX Book class and create a template to fill in on LyX, and all the text would be typeset with precision, all in its proper spot, with the excellent word spacing and justification controls that LaTeX excels at, since a Novel is the simplest type of book, page after page of the same font and formatting.  But I'd use the KOMA Book (scrbook) class or Memoir if necessary.  Also, I’ll probably just use InkScape, Scribus or Gimp for the front and back cover graphics and skip text altogether there.    The scenes would not be numbered like "2.4.2.1".  A Novel usually has the following layout:   Front Cover (use a graphics program: Scribus, InkScape or GIMP) Front Matter Table of Contents Dedication Prologue Main Matter (Parts, Chapters, Scenes, and insets for monologues or poem) Epilogue Back Matter Back Cover (use a graphics program: Scribus, InkScape or GIMP)


How to handle installed Managed Packages failing tests?

I have several AppExchange apps installed that are failing tests. What is the recommended approach to resolving this? Are tests run when a new package is installed? Is there a way to determine what is actually failing besides the name of the method and something like "expected true, actually false"? The test results rarely show enough information to be useful.   What I'm doing atm, is checking for updates for the packages, and then writing the company with the failing test results.   Any feedback would be appreciated.


How many full-time instructor positions to apply for as a Masters-holder?

I am leaving graduate school in May with a Master of Science in Mathematics.  For the past few weeks, I have been applying to full-time instructor/lecturer positions (mostly 2-year with a few 4-year).  I started with a list of ~40 and after whittling it down, have completed applications for 18.  The past few days I've been reading application blog posts and how-tos and the writers talk about applying to dozens of schools (even ).  And these are PhD holders with a lot more experience, which is making me worried.   There's a lot of information for PhD required professor positions so I wanted to ask-just how competitive is the teaching only scene?  I know that "applying to more places equals higher probability of getting a job" but I've more or less applied to everywhere I'd like to go.  However, I don't want to regret not lowering my standards and being unemployed for an entire year.


Is search a necessary navigation element?

I often have arguments about navigation at work with programmers who think search is a required part of any navigation. I think this is because programmers are advanced computer users who use search a lot and therefore have a preference for it. But I haven't seen any evidence that navigation is not effective without search. Many sites are easy to navigate and use without it, although it does of course add something when it exists. However, just putting search in your navigation isn't usually enough - search is a totally different paradigm and needs equal attention to be done right. You can't just "throw it in there" - it's not just a case of "setting up Lucene", as I sometimes hear.  So, is there any evidence that search is necessary for navigation to work?  No opinions please - looking for hard evidence, literature, references, etc.


Show how many edits I already suggested and if it's over the limit

I think there should be a markdown counting of suggestion limit, like how many I applied and how many I've left. Or is it already there and I didn't get it yet?


weird outcome using special chars in mysql query

Something weird happened, my (php-mysql)website is working but I don't understand how it's possibile and I'm looking for an explanation.  I have a database with a list of shops, every shop as a name that could have special chars in it like è, à, ì, ò and ù.  Here's how I constructed the link to the shop webpage so that I could have url without accents:  $noaccent_name = str_replace([" ","è","à","ù","ò","ì","'"],["-,"e","a","u","o","i","%27"], $shop_name);  echo 'link';   In the .htaccess file this link is rewriten by the rule:  RewriteRule ^eng/kiwishop/([A-Za-z0-9\-\+\']+)$ kiwishop.php?shop=$1&lang=en [NC,L]   Now the variable $_GET['shop'] is used by kiwishop.php to retrive all the data about that shop in the database. And so I need the vowels to "take back" their accents to match the name in the database. Here's what I have done:  $shop = htmlspecialchars($_GET['shop']); $shop = str_replace(["'", "%27", "e", "a", "o", "u","i","-"], ["\'", "\'", "è", "à", "ò", "ù", "ì", " "], $shop); $sql = "SELECT * FROM `{$lang_database}` INNER JOIN `Info` ON `shopid` = `Info`.`id` WHERE nome = '{$shop}'"; $result = query($sql, $connection);   And it's perfectly working but then I realized there is a big mistake because all the vowels are replaced with vowels with accent.   For example if I have a $shop_name = "Art Caffè" in the database. In the link I have "art-caffe". But the $shop variable that I use in the query is "àrt càffè" and if I dump the variable $sql I get:  SELECT * FROM `Kiwishop` INNER JOIN `Info` ON `shopid` = `Info`.`id` WHERE nome = 'Ã rt cÃ ffÃ¨'   But the result of the query gives me what I was looking for, i.e. all the data related to the shop "Art Caffè". How is that possible? I don't wanna change the code because I had hard time make everything work, but I want to understand the reason so that I know what I'm doing.  Can someone see why that's happening? Thanks!


Why bounty messages cannot include line breaks?

I published  in Unix & Linux StackExchange.  I've added a bounty with quite a long bounty message. The original bounty message included 3 line breaks so to be comprised of three passages (I've added the line breaks with CTRL+Return/Enter):     From all I've read so far, a "callback" seems to me as "a function   that is being called back after a given event was triggered". So far   so good, but I feel a simple, clear example for this in Bash is yet to   have been given (an answerer might first need to example an event in   Bash).      Either way, example in some current answers seem to me a bit   complicated-for-no-good-reason in a way that makes them undidactic or   including details that might be uneeded to explain how the callback   concept in Bash.      Please do not abstain longevity, if it will make a code example   simpler, more rewarding, and inclduing less Bash-keywords   (encapsulated behavior) that might not be familiar to Bash newbies and   will make the attempt to understand the code example even more   confusing and hence undidactic.   Sadly, it seems that this site doesn't support line breaks in bounty messages so now the current state is that the bounty message appear as one big block of text which is less , and less comfortable or efficient to read:     From all I've read so far, a "callback" seems to me as "a function   that is being called back after a given event was triggered". So far   so good, but I feel a simple, clear example for this in Bash is yet to   have been given (an answerer might first need to example an event in   Bash). Either way, example in some current answers seem to me a bit   complicated-for-no-good-reason in a way that makes them undidactic or   including details that might be uneeded to explain how the callback   concept in Bash. Please do not abstain longevity, if it will make a   code example simpler, more rewarding, and inclduing less Bash-keywords   (encapsulated behavior) that might not be familiar to Bash newbies and   will make the attempt to understand the code example even more   confusing and hence undidactic.   I ask the community, first in the context of Web Accessibility, then in the context of general reading comfortability, to add these options:   An option to support line breaks (CTRL+Return/Enter) in bounty messages. An option to edit bounty messages (AFAIK, as of 09/23/2018, these cannot be edited).


How to enable parental control in specific user account in Windows 7?

I have my laptop used by my room mates, I have a user account and everyone knows the password for the same. I don't want to put parental controls on my user account and want to create a room mate specific user account and set parental controls for specific things as below:   No Access to specific drive/ folder in the drive. A installed software in my login available/non-available to other login Limited usage of internet sites(I guess thats to be done in browser)   Just needed that much, :P hope no one gets mad on me. I tried to solve issue by my own but was unsuccessful in 2nd part. :(


How come we write drought and draught but pronounce [draut] and [dra:ft] or write enough and though but pronounce [i’naf] and [đou]?

How come we write drought and draught but pronounce [draut] and [dra: ft] or write enough and though but pronounce [i’naf] and [đou]?


How do I get rid of these bats on minecraft

I was building a mob zoo and my bats got out and they fly around and annoy me. How do i remove them?


I have a daily time series and when trying to check for normality I am getting the QQ plot below. Any ideas as to what is the plot saying about my data?


Can averaging all the variables be seen as a crude form of PCA?

This question just occurred to me out of the blue. PCA is a way to reduce dimensions. Another way that is often (perhaps too often) used is to take mean values of two or more variables. This is done a great deal to create "scales" or "ratings" that get published in the popular press about various political issues. Dimensions are naively "averaged" and this cumulative "average" is portrayed as a magical one-number-sums-all figure.  Is this, nevertheless, a very crude relative of PCA? If so, what assumptions does it have? I can think of the following:   Sphericity is perfect or near-perfect. All variables are perfectly orthogonal from all other variables. Variables are all perfectly scaled against each other.   What else would there be?


I am learning java programming from   This guy, till now have been using the void keyword before declaring any method but once he reached to the passing parameters in methods part, he starting using the public keyword instead of the void keyword. Why did he start using public instead of void?  I have a vague understanding of both the keyword but it would be better if you could explain these keywords to me too.


The closure of $\{ z:|f(z)|<c\}$ is the set $\{z:|f(z)|\leq c\}$.

Exercise: Let $f$ be entire and non-constant. For any positive real number $c>0$ show that the closure of $\{ z:|f(z)|<c\}$ is the set $\{z:|f(z)|\leq c\}$.   Solution: Let $\varepsilon>0$ and define $A:=\{ z:|f(z)|<c\}$. Then, because $f$ is continuous (via entire) and non-constant, there exists $z\in A$ such that   $$B(c;\varepsilon)\cap A \neq \varnothing .$$  That is to say that $c$ is a limit point of $A$. Since $A^-$ must contain all of its limit points, we have that $\{z:|f(z)|\leq c\}$.    Is my solution correct? I have another way of doing it using a sequence $z_n\to z$, but I would prefer to use the above if it correct. The reason I am feeling unsure about my solution is because I am not sure how we know (geometrically) that $|f(z)|$ goes all the way up to the boundary (i.e. $c$). Is it safe to say that $|f(z)$ gets infinitely close to $c$ but does not touch because $f$ is entire & non-constant? FYI I am new at these concepts so please be a detailed as possible. Thank you in advance!  Note: I am using the notation $A^-$ to indicate the closure of $A$. This is the notation used in my text (Complex, Conway) and I suspect it is used as to not be confused with the complex conjugate.


I have made two accounts and they are both stuck on the Pokeball loading screen, what I'm saying is the Pokeball keeps spinning and I cannot get on the game. I'm turning my phone into airplane mode does not work.


Switching easily between windows 8 and Ubuntu

Is there an easy way to switch between Ubuntu and Windows 8 without restarting? I need both for my work and restarting everytime seems cumbersome but also inefficient. I've heard that it was possible to do so for windows 7 though Vmare  Machine: Lenovo g500


Are there specific rules about which races can mate with each other?

Is mixing races allowed? How would you choose which perks to take from each race?  For example: There are Half elves and half orcs but what about a half dwarf? or a half gnome? or even a half-Elf Half-orc?


Changing 'data block' name of object from python script

I am trying to change the name of the object in the data block from the python script. The operation name is: bpy.ops.outliner.id_operation(type='RENAME').  But I am not experienced on Blender and I don't know how to use that function, so can someone help me on that subject please?    Thanks in advance.


It Won't Render: Stuck on the 1st 4 tiles, played with Resolution, sample size and max steps with no luck

So I'm at that step where I am finally ready to Render my first big project. Aaaaaand it's been stuck on the first 4 tiles for the last 2 hours?   I am using a MacBook Pro Processor: 2.5 GHz Intel Core i5 Memory: 4 GB 1600 MHz DDR3 Graphics: intel HD Graphics 4000 1024 MB  (I include these because I have no idea what affects a computers ability to render but I assume it's one of them, most liekly the graphics card).  So anyways here are the pictures, as you can see I played with changing the resolution, the sample size and the max steps to see if I got different results but it just keeps getting stuck at those 1st four tiles. I've rendered a few other small projects successfully but this was my first time changing some values. I assume i've managed to accidentally change the wrong values and thats causing some conflict thats either stopping the render itself or is making it just too much for my computer.  My goal was the render this particular picture at a good enough resolution and clarity that it could then be made into a poster. So i wanted the resolution to be good and the sampling to be high.       Since writing this there has been no change to any of the numbers at the top of the render result (the time left, etc)


Host resources management - vSphere Client

I'm using vSphere Client version 6.7, having 2 hosts in a cluster. i want to know before i'm entering one host into maintenance mode, if the other host will be able to hold both servers resources. yes i know, i could calculate it by using free/used space in CPU,Storage,Memory fields. i want to know if there is a simulator or something like that that will show me what will be the situation after i will move all VMs to the other host. Thanks!


How to prove this inequality of bounded complex number.?

$|a_1\cdots a_m - b_1\cdots b_m|\leq \sum\limits_{j=1}^m|a_i-b_i|$  Where $|a_i|\leq 1, |b_i|\leq 1$, and they are any complex number satisfying the condition.


No response from Professor; how should I remind him about writing a recommendation for me?

I'm applying to a BS/MS program and I'm gathering recommendations. I'm an international student from China and I was transferred to my current college last year.  Two weeks ago, I went to see my professor during his office hours to ask if he could write me a recommendation letter. He agreed and told me to email him.  I sent my request a week later and it was just a general email asking for recommendation (without mentioning when I'd visited him).   I still haven't got a response from that professor. It's possible that the professor didn't recognize me in the email, since I sent that only one week after going to his office.  Should I leave him a reminder in a follow-up email? Or should I do so in person?


Ability to filter your questions by unanswered or not chosen

I have a lot of questions and I really like to give approval to all of them to ensure I am giving feedback to the people answering and not have any lingering questions.    Is there anyway to filter my questions to just see the one that don't have an answer selected? This will save me time instead of just scrolling through all questions.


Why does hair know when it needs to stop to grow

I'm still not quite sure if head hair grows endlessly, or if it stops at some point, but that's not the question.  When the hair on my leg grows, it obviously doesn't grow endlessly, but it also stops at some point. I learnt that hair is dead matter, so why does the body know that my hair reached maximum length, and realizes I cut it when I did?


GRUB2 shows Windows 7 or Windows Recovery Environment instead of Windows 10

This is a Q&A that I recently have figured out, so I have posted the answer below.  After installing Windows 10, every time I get a kernel update or I run the update-grub2 it always shows Windows 7 or Windows Recovery Environment instead of Windows 10.  How do I fix this permanently?


If I were to write a sentence beginning with a question, where would the question mark go? It does not seem right at the end of the sentence.  For example:     Was there something changed recently because internet shouldn't be dropping this low, even for a small plan.   The format of the sentence doesn't feel right having a question mark at the end and it does look right having one at the end of question:     Was there something changed recently? because internet shouldn't be dropping this low, even for a small plan.   What is the correct way to format a question like this?


intuition behind cyclicality of the trace?

The trace of a matrix product is "commutative" (i.e. cyclical): $$\operatorname{trace}(AB)=\operatorname{trace}(BA)$$  I know how to prove this. I was wondering, are there any intuitive ways to understand why this must be true? One reason why I don't see it intuitively is that I don't really understand intuitively what the trace represents (e.g. geometrically).


How come when I try to cd into a new parition nothing happens?

My primary partition is C:\  But I want to cd into G:\  When I type in on command prompt "cd G:\", nothing happens. It just prints the directory I'm in which is C:\  My OS is Windows 8.


Use two or more IP addresses to prevent DoS attacks

N00b question  But say I had a dedicated server with two IP addresses, and the software (We'll just use Apache as an example) was using both IP address to serve content, in the event of a DoS attack on one of the IP addresses, could I just use something like IP Tables to null route/drop all incoming connections on one of the two IP addresses, effectively rendering the attack useless and still serving the users?


$(A\cap B)\cup C = A \cap (B\cup C)$ if and only if $C \subset A$

I have a set identity: $(A \cap B) \cup C = A \cap (B \cup C)$ if and only if $C \subset A$.  I started with Venn diagrams and here is the result:   It is evident that set identity is correct. So I started to prove it algebraic:  1) According to distributive law: $(A \cap B) \cup C = (A \cup C) \cap (B \cup C)$  2) ...  I stuck a little. Because $C$ is a subset of $A$. I thought of pulling out: $(B \cup C)$ but it seems wrong step to me.  How to prove this identity having in mind that $C \subset A$?  Updated  Venn diagram for $C ⊈ A$


How to tell if a JavaScript function is defined

How do you tell if a function in JavaScript is defined?  I want to do something like this  function something_cool(text, callback) {     alert(text);     if( callback != null ) callback(); }   But it gets me a     callback is not a function   error when callback is not defined.


Is rain considered Running Water for a Vampire's weakness?

I'm currently playing Curse of Strahd. Personally knowing some actual Vampiric Lore and having also read through the Monster Manual, I know that running water is a weakness to Vampires.   Is rain considered Running Water for a Vampire's weakness Harmed by moving water?   This was brought up, in our game, due to Strahd standing out in the rain for our first time meeting him.


Doesn't matter if it's selected or not, but whenever I click LMB, the cursor always appears there. It's also preventing me from selecting objects by clicking; I can only drag select, and it sucks trying to select a single object through bunches of them. I've been able to blend on other devices without this issue. How do I turn this off?


How does the Doctor keep track of his age?

Throughout the Dr. Who series, the doctors have claimed to be hundreds, even thousands of years old, (the tenth and eleventh both claim to be around 900, but throughout the series, eleven jumps into the thousands, even though its only been a few years for his companions, and now the 12th claims to be 2,000) but in relation to what?  He is constantly jumping around through time, making it difficult to track.  Does he claim his age to be in relation to Gallifrey as if he hadn't left or it hadn't been burned, (or saved, it's all too timey-wimey for me to make sense of) or does he simply not know?


I would like to execute a number of bash commands from a Rakefile.  I have tried the following in my Rakefile   task :hello do   %{echo "World!"} end   but upon executing rake hello there is no output? How do I execute bash commands from a Rakefile?  NOTE:This is not a duplicate as it's specifically asking how to execute bash commands from a Rakefile.


How can I install apt packages non-interactively?

If I run:  sudo apt-get --yes install postfix    or  sudo bash -c 'yes | apt-get --yes install postfix'   an interactive prompt appears to configure postfix. I need to automate the installation of postfix (I can modify the configuration files after the install).  Is there some magic that lets me install postfix (and other package) without human intervention?


How can I convert from uppercase to lowercase all directories and sub-directories in Ubuntu 16.04.2?

Path:  / DIRECTORY_ROOT        /SUB_DIRECTORY   And convert that to:  / directory_root        /sub_directory   I tried: rename 'y/A-Z/a-z/' * but it only changes the root directory and not sub directories. I'm new to Ubuntu, thanks for the help!


Finding $\lim_{n\to\infty} a_n^n$ where $a_n=\frac{(n!)^2}{(n+k)!(n-k)!}$

For each $k\in\mathbb N$, I am trying to find $\lim_\limits{n\to\infty} a_n^n$ where $$a_n=\frac{(n!)^2}{(n+k)!(n-k)!}$$   Simplifying the factorials I have $$a_n=\frac{n(n-1)\ldots(n-k+1)}{(n+k)(n+k-1)\ldots(n+1)}$$  I tried to rewrite this as $$a_n=\frac{\left(1-\frac{1}{n}\right)\left(1-\frac{2}{n}\right)\ldots\left(1-\frac{k-1}{n}\right)}{\left(1+\frac{k}{n}\right)\left(1+\frac{k-1}{n}\right)\ldots\left(1+\frac{1}{n}\right)}$$  But all this tells me is that $a_n\to 1$.  Using Stirling's approximation, I think I also have $$a_n\sim \frac{n^{2n+1}}{(n+k)^{n+k+\frac{1}{2}}(n-k)^{n-k+\frac{1}{2}}}$$  Don't think this helps either. Any hint would be great.


Find the value of $\space\large i^{i^i}$?

Is $\large i^{i^i}$ real ? How to find it?   Thank You!


Why touching tooth filling with aluminum foil feels so weird?

I have read that there is and electrical current, but why and how?    How big can this current (and voltage) be (does an amount of foil, saliva, tooth filling have any influence on this)? Can it "dry out" after some time? Can it be harmful if occurs for longer period?


Overlapping positive definite block matrices

Let $A \in \mathbb{R}^{p \times p}$ and $B \in \mathbb{R}^{q \times q}$ be nonsymmetric positive definite matrices in the sense that $v^T A v > 0, \forall v \in \mathbb{R}^p$ and $v^T B v > 0, \forall v \in \mathbb{R}^q$.  I know that $A \oplus B$, i.e. a matrix with a block structure \begin{align} \pmatrix{A & 0 \\          0 & B} \end{align} is positive definite and I also know that if $p=q$, then $A+B$ is positive definite as well.  Can I say that as well if the blocks overlap partially? When?   For instance a matrix as follows: \begin{align} \pmatrix{a_{11} & a_{12} & a_{13} & a_{14} & 0& 0\\          a_{21} & a_{22} & a_{23} & a_{24}& 0& 0\\          a_{31} & a_{32} & a_{33} + b_{11} & a_{34} + b_{12} &b_{13}&b_{14}\\          a_{41} & a_{42} & a_{43} + b_{21} & a_{44} + b_{22} &b_{23}&b_{24}\\          0 & 0 & b_{31} & b_{32} &b_{33}&b_{34} \\          0 & 0 & b_{41} & b_{42} &b_{43}&b_{44}} \end{align}


Why is bash not respecting ${PATH} and/or symlinks?

I am on OSX and installed Homebrew to get the GNU coreutils.  I wanted gsort to be used instead of the preinstalled sort command so I created a symlink to gsort.  My limited experience tells me that running sort from the CL or in a script will use gsort, however that's not what's happening:  $ which gsort; which sort /usr/local/bin/gsort /usr/local/bin/sort $ ll /usr/local/bin/ | fgrep sort 1083450 lrwxr-xr-x  1 alex  admin  -   34B Mar 23 15:56:52 2016 gsort@ -> ../Cellar/coreutils/8.25/bin/gsort 1083466 lrwxr-xr-x  1 alex  admin  -   35B Mar 23 15:56:52 2016 gtsort@ -> ../Cellar/coreutils/8.25/bin/gtsort 1088327 lrwxr-xr-x  1 alex  admin  -   34B Mar 23 16:57:41 2016 sort@ -> ../Cellar/coreutils/8.25/bin/gsort $ echo ${PATH}  /usr/local/opt/gnu-sed/bin/:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin $ gsort --version | fgrep GNU sort (GNU coreutils) 8.25 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. $ /usr/local/bin/sort --version | fgrep GNU sort (GNU coreutils) 8.25 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. $ sort --version | fgrep GNU sort (GNU coreutils) 5.93 the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.   Notice that when checking the version of gsort and sort (when using the absolute path to the symlink) it properly shows the newer coreutils version, but just running sort still gives me the old, preinstalled version.  Can anyone tell me why?


I have an array like this:  ["News & Politics", "Personal Journals", "Society & Culture", "Technology", "Arts", "Natural Sciences", "Business", "Comedy", "History", "Tech News", "TV & Film", "Design", "Performing Arts", "Education", "Christianity", "Investing", "Sports & Recreation", "Professional", "Social Sciences", "Automotive", "Science & Medicine", "Management & Marketing", "Sexuality", "Philosophy", "Self-Help", "Literature", "Buddhism", "Places & Travel", "Music", "Language Courses", "Careers", "Food", "Kids & Family", "National"]   I need to "push" these values into a select with each of the items in the array being it's own option.  How do I go about accomplishing this?  The array is stored as variable all_cat_unique, but (of course) the following doesn't work. I just appends the entire array to the select a bunch of times.  $.each(obj.entry, function(i, data) {      $('#all-categories').append('<option>'+all_cat_unique+'</option>'); });   Thanks.


How long does the Final Fantasy XI main story take to complete?

I'm looking for relative values here. For example, if it takes a person about 40 hours to complete only the story for the average Final Fantasy, then how long, in comparison, would the Final Fantasy XI story take?  In other words, how much longer is the FF-XI storyline completion compared to Final Fantasy storylines?  This does not include expansion packs or downloadable content.


Is $\mathbb{R}^\omega$ endowed with the box topology completely normal (or hereditarily normal)?

Just out of curiosity, I'd like to know more properties of box topology. I found  quite interesting, but unfortunately, it hasn't attracted too much attention. I also searched it in MathOverflow, the comment by Ramiro de la Vega in  asserted it's been known the answer is negative. However, I can't obtain any further information on the Internet. Could somebody provide a disproof, or at least offer some useful links?


I ran the meat through mincer once, formed burger approx. 3cm high, seasoned it, oiled from one side and put it in very heated pot and I put the lid on it. When I was turning it the other side down, it started to fall apart.  What do I need to change in my process to keep the hamburger whole? I guess the flaw can be that the meat is not enough oily, it didn't taste very oily. But the meat that I have isn't oily, will adding some external oil fix it?


What are the automorphisms acting on $Q\sqrt[3]{2}$ that fixes Q?

For the field $Q(\sqrt[3]{2})$, the elements in the field are in the form of $a + b\sqrt[3]{2}+c\sqrt[3]{4}$, where a,b,c, are elements of Q. Is the automorphism group that fixes Q  $C_{3}$? multiplying all elements in $Q(\sqrt[3]{2})$ by $\sqrt[3]{2}$, will result a cyclic cycle of period 3, but what about mapping $\sqrt[3]{2}$  to  $-\sqrt[3]{2}$? For extension fields like $Q(\sqrt{2},\sqrt{3})$, the mapping towards a radical's negative counterpart is part of the automorphism group. Should this also be part of the automorphism group that fixes Q?


How many squares can fit in a circle without going outside the perimeter?

How many squares of side length $x$ can fit in a circle of diameter $n\cdot x$, where $n$ is any positive number, such that none of the squares overlap the perimeter of the circle and all of the squares are aligned in a grid (i.e. no zig-zagging of edges)? For example:  This is for a project I'm doing using Excel, so it'd be ideal to have a formula, versus an infinite series or a c++ function. Thanks! [Edit]:  Some folks have suggested  but I think that only works when the circle is very large (relative to the squares).  For example, a circle of 3x gives a result of 0.4, when clearly (from the image above) you can fit 4 squares inside.


Will Internet Explorer run on Windows 10?  I can't seem to find an answer to this anywhere.  I have just updated to Windows 10 and need to be able to do web development testing on Internet Explorer, but when I go to  it says "Looking for Internet Explorer? You’re in the right place, but Internet Explorer requires a Windows PC."


Is there a way to find $a$ and $b$ keywords in an affine cipher when only ciphertext but no plaintext is known?

I know simple formulas like  $$E(x) = (ax+b)\pmod n$$  where $E(x)$ stands for encryption,  $$D(y)= z(y-b)\pmod n$$  where $D(y)$ stands for decryption,  and   $$ax==1\pmod n$$  Assuming someone gives us an encrypted string, is there a way to find $a$ and $b$ from that string? If not, what informations we should have to find $a$ and $b$ keywords from the encrypted string? Is there a way to find a and b keywords in an affine cipher when only ciphertext but no plaintext is known?    Note that this is not a duplicate of . In that other question, the user knows beginning of both encrypted and decrypted message.


This function is generating a array with json objects on it:  var estoque={}; function unpack_estoque(tnm,total,estoque_vl,id,tid,st) {     tnm=tnm.split("|");     total=total.split("|");     estoque_vl=estoque_vl.split("|");     id=typeof id != 'undefined' ? id.split("|") : null;     tid=typeof tid != 'undefined' ? tid.split("|") : null;     st=typeof st != 'undefined' ? st.split("|") : null;      for (var i in tnm)         estoque[i]={             "id": id != null ? id[i] : null,             "tid": tid != null ? tid[i] : null,             "total": total[i],             "estoque": estoque_vl[i],             "tnm": tnm[i],             "st": st != null ? st[i] : null         }; }   Now how do i get the estoque length to loop through the collected items?  estoque.length returns undefined while for (var i in estoque) loops through JSON object and not estoque[] root array.  Thanks.


How can I calculate the distribution of 3d6, keep and rerolling any 1s and 2s, once?

The way my DM wants to try is roll 3d6 and reroll any 1's or 2's once. If you roll a 2 and the reroll ends up being a 1 you have to take the 1.


Read a particular value from INI file to Text box

I need to be able to read the "Country=" section of the INI file and place the value in a text box in my application? The text box is called "cbxctry". I have looked at using streamreader but not sure if this is correct? Please let me know if you need any further information.  INI File  [Carrier] Name=Singtel ChargeStructure=Business Rates CountryId=88 Country=Singapore Ident=99101 MeterRate=0 DefaultChargeBand=N NetworkDigits=  [CallCategories] N=National I=International M=Mobile L=Local F=Free P=Premium DE=Directory Enquiries     CODE  private void btnnewtariff_Click_1(object sender, EventArgs e) {     Stream myStream = null;     SaveFileDialog openFileDialog1 = new SaveFileDialog();      openFileDialog1.InitialDirectory = @"D:\tig2020\Carriers\'";     openFileDialog1.Filter = "inf files (*.Inf)|*.Inf|All files (*.*)|*.*";     openFileDialog1.FilterIndex = 1;     openFileDialog1.RestoreDirectory = false;     openFileDialog1.OverwritePrompt = true;      if (openFileDialog1.ShowDialog() == DialogResult.OK)     {         try         {             if ((myStream = openFileDialog1.OpenFile()) != null)             {                 using (myStream)                 {                     txtnewtariff.Text = openFileDialog1.FileName;                 }             }         }         catch (Exception ex)         {             MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);          }


Workaround that allows the use of digits as part of counter names?

I tried to define indexed counters, such as x1, x2, . . . etc, by defining them like this : \newcount\x1, \newcount\x2, . . . etc, but it didn't work. Is there a workaround for this in TeX or LaTeX ?   I have written a small tex-file that illustrates what happens when you try it. Note added : With the remark made by @cfr, that in LaTex one may use the command \newcounter{name} the question has a good answer that cannot easily be found by using the search engine. (I have some good reference books for TeX, but not for LaTeX.)  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%  Example tex-file that illustrates what happens  %% %%  when you use a number in the name of a counter  %% %%                                                  %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%           \documentclass{article} \usepackage[paperwidth=0.75in, paperheight=1.5in]{geometry} \pagestyle{empty}  \begin{document}  \newcount\a  \newcount\b \newcount\c7  \a=1   \b=41 \c7=78  \noindent a = \number\a   \par \vskip 5pt \noindent b = \number\b   \par \vskip 5pt \noindent  c7 = \number\c7   \end{document}


Is it possible to autosave as docx and pdf at the same time?

In MS Word Mac, is there a native way to save the document I am currently working on as .docx and a .pdf file with one click?  I need the document to be in both formats.  behavior now: first I save it as .docx by clicking cmd + s, then go to save as > pick .pdf from the dropdown > click export  expected: cmd + s results in 2 files, one .pdf and one .docx with current changes.


Is there anyway for Ubuntu, or any Linux flavor/distro, that natively supports it? I installed a clean copy of Ubuntu and only a few songs of my 100,000+ music library was imported. (to Rhythmbox). My computer in question does not have internet access. No terminal (sudo apt get) will work unless the packages (support files) can be downloaded then sideloaded (via USB) to the computer


Java How to get the index of a Map of HashMap

Forgive me if  it seems simple but I couldn't figure it out easily. I thought about using a loop but was wondering if anybody knows an easier way: I have:  Map<String, Integer> map = new HashMap<>();          map.put("ClubB", 1);         map.put("ClubA", 2);         map.put("ClubC", 2);         map.put("ClubD", 2);         map.put("ClubE", 3);         map.put("ClubF", 2);         map.put("ClubG", 2);   I need to get keys or values at specific index in my tests. For example I need to get the key and value at index 3 etc. The reason is that I use a comparator and sort the Map and would like to show that the value at a specific index has changed.  Thanks for any ideas.  UPDATE:  I used:  HashMap leagueTable = new HashMap(); Map<String, Integer> map = sortByValues(leagueTable);   public <K extends Comparable<K>, V extends Comparable<V>> Map<K, V> sortByValues(final Map<K, V> map) {         Comparator<K> valueComparator = new Comparator<K>() {             public int compare(K k1, K k2) {                 int compare = map.get(k2).compareTo(map.get(k1));                 if (compare == 0) {                     return k1.compareTo(k2); // <- To sort alphabetically                 } else {                     return compare;                 }             }         };         Map<K, V> sortedByValues = new TreeMap<K, V>(valueComparator);         sortedByValues.putAll(map);         return sortedByValues;     }   I then used aloop to print out values:  for (Map.Entry<String, Integer> entry : map.entrySet()) {                      System.out.println( entry.getKey() + ", " + entry.getValue() ); }


The question is not about the real photons bursted out of an atom and their size (I call them real photons) but about the quantized modes in a box and that they are called photons (I call them QED photons). I wonder what common has the real photon and the QED  photon with each other.  According to QED quantization procedure of the EM field as known Debye decomposed EM field in a box in Fourier components, then Born, Jordan and Heisenberg quantized the amplitude of the standing waves (SW) so the energy was devided into pieces hv and hence the amplitude of the SW is multiple of n (integer). So it turns out that the photon in QED is a standing wave with energy = hv whereas its length seems = length of the box. There are some questions about this notion of photon (as pictured in QED) I want to find answers.   The standing wave fills the whole box at once – so a photon appears on top of the existing standing wave like dropping above immediately, whereas the atom in the walls should have delivered the energy hv and this seems not relativistic (there should be some moment that energy left the wall, so at that moment there can not be EM amplitude near the other wall or in the center of the box). As the length of box can be varied it turns out that the length of the photon depends on the length of the box, which is unknown to the atom. For distant objects this seems extremely unbelievable as for item 1 so for item 2. (but QED says that one easily stretches the box to infinity and all is the same.) In order to insure the release of proper frequency an instantaneous process is needed which to measure the distance of the box and to deliver the info to the emitting atom.   I think some answers maybe based on Heisenberg uncertainty principle though I haven’t seen these questions ever asked anywhere and nonetheless some answers. I hope someone knows a paper or book where they are posed and cleared and will be so kind to share this knowledge.


I have an issue with Ubuntu 18.04. I was preparing a presentation and I had to force the shut down since the screen was blocked. When I rebooted this was the message (on black screen), no more. I have tried to do different things and the most relevant lines are: 1)Started GNOME Display Manager.ever.tcher Service....system changes.pp link was shut down 2)Stopping user manager for UID120.... I trided with systemcl status display-manager from root: gdm-service - GNOME Display manager Loaded:loaded (/lib/systemd/system/gdm.service; static; vendor preset enabled) Active:Inactive(dead) I tried to check with journalctl to understand a bit more and apparenly this is the first reboot since I have installed a huge software (suspicious). I would not be surprised if there is some mismatching. I have isolated all the " install " in dpkg.log when I installed the software, but I don't know if the solution can be to remove them one by one since they are quite a lot. Any suggestion please?


Is Jean Valjean lying when he tells Javert that he will turn himself in after 3 days?

In , when Jean Valjean is confronted by Javert in the hospital, he says that if he is allowed to ensure Cosette's safety he will turn himself in in 3 days.  JVJ: Before you say another word Javer, listen to me, there is something I must do.  This one leave behind a suffering child. There is none but me who can intercede. Three days are all I need.  Then I'll return. I pledge my word. Then I'll return... JAV: You must think me mad. I've hunted you across the years, men like you can never change. A man such as you.  Jean Valjean then defeats Javert and escapes to find Cosette.  After securing her safety, however, he does not turn himself in but continues to run. Is Jean Valjean lying about his intentions or did he change his plans when Javert didn't believe him, and if so, why?


Question:  Prove that a finite subset in a metric space is closed.  My proof-sketch: Let $A$ be finite set. Then $A=\{x_1, x_2,\dots, x_n\}.$ We know that $A$ has no limits points. What's next? Definition: Set $E$ is called closed set if $E$ contains all his limits points.  Context: Principles of Mathematical Analysis, Rudin


Is it possible to use Cognito Forms offline or some way to implement an offline solution?

Is it possible to use  offline, or some way to implement an offline solution?


I just installed Ubuntu 14.04 64-bit and enabled the nvidia drivers. Now I am trying to install WINE but I get the message:  nvidia-libopencl1-331 has to be removed before installing WINE (translated from Dutch). Is this a bug? Or should I proceed removing this package?


Is it okay to upvote someone's questions so I can speak with them in chat?

I had a situation earlier where I was trying to help someone with an issue. If I upvote all their questions so we can move it to chat, is that ok? They did not have enough rep to chat.


how to detect error and restart microcontroller for embedded system with Esp 12 or Esp 32

one thing that make me confused is how the microcontroller notice the errors and restart by itself let me give an example we have cooler system with Esp 32 and temperature sensor,when temperature be Above 25 centigrade degrees cooler will work until temperature reduce to 25 degree . all the thing will work in the loop . for example after 1 week of work errors come to esp , how is possible that Esp notice the error and restart automatically for fixing the error . i don't want restart the board manually


Find OS by interpreting TCP/IP fingerprints when using nmap

When I ran the command: nmap -O ip_address to identify the OS, I got the following result:  OS:SCAN(V=5.05BETA1%D=8/23%OT=22%CT=1%CU=42341%PV=N%DS=0%DC=L%G=Y%TM=4A91CB     OS:90%P=xxxx)SEQ(SP=C9%GCD=1%ISR=CF%TI=Z%CI=Z%II=I%TS=A)OPS(O1     OS:=M400CST11NW5%O2=M400CST11NW5%O3=M400CNNT11NW5%O4=M400CST11NW5%O5=M400CS     OS:T11NW5%O6=M400CST11)WIN(W1=8000%W2=8000%W3=8000%W4=8000%W5=8000%W6=8000)     OS:ECN(R=Y%DF=Y%T=40%W=8018%O=M400CNNSNW5%CC=N%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+     OS:%F=AS%RD=0%Q=)T2(R=N)T3(R=Y%DF=Y%T=40%W=8000%S=O%A=S+%F=AS%O=M400CST11NW     OS:5%RD=0%Q=)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%T=40%W     OS:=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)     OS:T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=N%T=40%IPL=164%U     OS:N=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=40%CD=S)   How can I find the most likely OS on this scanned computer? How can I interpret this result? What suggests that the OS may be Linux for example, and what suggests that it may be another OS, for example Windows? I am trying hard to understand it. Please help me. Thanks in advance


I suggest creating a definite list of guidelines for when to migrate questions from one site to another and adding it to the Community Wiki. I didn't find it in one place.  If I'm wrong, please point me to that place.


Unable to use or open Notepad++ after installation

I have recently installed Ubuntu 18.04 on my laptop. I tried installing Notepad++ using the following commands:   sudo snap install notepad-plus-plus     However, after installing it, I can see Notepad ++ is installed but I am unable to open it.  When I run snap run notepad-plus-plus I get the following results:  wine cmd.exe /c echo '%ProgramFiles%' returned empty string, error message    "wine: WINEARCH set to win64 but '/home/my-username/snap/notepad-plus-plus/common/.wine'   is a 32-bit installation."   I also tried the suggestion mentioned in     but can't get Notepad ++ to open.


Problem: How many 5-digit numbers have distinct digits and are divisible by 3? My direction: I have tried to find all numbers with 5 digits that are divisible by 3 (30000 numbers) and then I will subtract from it numbers that do not have 5 distinct digits but I can't find it.


Find the maximum value of $x_1x_2+x_2x_3+\cdots+x_nx_1$ if $x_1+x_2+\cdots+x_n=0$ and $x_1^2+x_2^2+...+x_n^2=1$.  I can get by Cauchy-Schwarz that $x_1x_2+x_2x_3+\cdots+x_nx_1 \leqslant 1$, but can expression $x_1x_2+x_2x_3+\cdots+x_nx_1$ be smaller?


I have below code which is submit form using Jquery AJAX with image upload. When ajax call server file I cannot acces $_FILES variable.  function submitForm()         {               var data = $("#ff").serialize();              $.ajax({                  type : 'POST',                 url  : 'register_process.php',                 data : data,                 contentType: false,                  cache: false,                                    processData:false,                  beforeSend: function()                 {                      $("#error").fadeOut();                     $("#register_btn").html('&nbsp; sending ...');                 },                 success :  function(response)                 {                           if(response=="ok"){                          //$("#register_form_succ").fadeIn();                         $("#register_form_succ").html('Registration successful Click here to login');                     }                     else{                          $("#error").fadeIn(1000, function(){                                   $("#error").html(' '+response+' !');                         });                     }                 }             });             return false;         }   and HTML below  <form method="POST" action="register.php" enctype="multipart/form-data" id="ff" name="reg">
                      I am new user !

                                      Full Name *:                     <input type="text" placeholder="Please enter Full Name" name="name" id="name" autofocus>                                                       Username *:                         <input type="text" placeholder="Please enter Username" name="username" id="username">                                                       Password *:                         <input type="password" placeholder="Please enter Password" name="password" id="password">                                                       Email *:                         <input type="email" placeholder="Please enter Email" name="email" id="email">                                                       Photo *:                         <input type="file" name="photo" id="photo">                                   <input type="submit" class="sendButton" name="register_btn" name="register_btn" value="Save"/>
I already Registered. Login here
                                 </form>   But in register_process.php i cant get $_FILES variable. it is blank


Intro to quantum computing for programmers

I'm looking for an entrypoint to learning about quantum computing to which I'm exposed only by popular science articles and some qiskit materials so far. I understand that it's entirely possible that I'm insulated from the underlying math and implementation details, but I'm not interested in that. Considering my background is in classical programming, mostly imperative languages, what's a good book or set of other materials to get me started but with a view to eventually go deep?


Why (\x)^2 and \x^2 produce different results in Tikz plot?

(\x)^2 will plot correct parabola, while \x^2 will have negative x branch upside down. Why () are required for this formula to work?  \documentclass[10pt]{article} \usepackage[utf8]{inputenc} \usepackage{tikz} \usetikzlibrary{shapes.geometric} \usetikzlibrary{shapes.misc}  \begin{document} \begin{figure}[!htb]     \begin{tikzpicture}         \draw[very thin,color=gray] (-4.1,-4.1) grid (4.1,4.1);         \draw[->] (-4.2,0) -- (4.2,0) node[right] {$x$};         \draw[->] (0,-4.2) -- (0,4.2) node[above] {$f(x)$};          \draw[thick,purple,domain=-3:3,smooth] plot (\x,{0.5*\x^2});         \draw[thick,brown,domain=-3:3,smooth] plot (\x,{0.2*\x^3});     \end{tikzpicture}  \caption{$y=1/2 x^2, y=1/5 x^3$} \end{figure}  \end{document}


improving fitting results of neural network

I've trained fitnet network for prediction steel's yield stress with MATLAB ann toolbox.   The neural network should predict yield stress. I have about 250 vector inputs. Every input vector has 12 parameters as inputs plus one parameter as target (yield stress). ann should predict yield stress.  The inputs are weight percent of chemical elements that are used in steel.  Here is my code snippet:  inputs=transpose(inputs); targets=transpose(targets);  net =  feedforwardnet(20); %net.trainParam.max_fail=1000  % Setup Division of Data for Training, Validation, Testing net.divideParam.trainRatio = 70/100; net.divideParam.valRatio = 15/100; net.divideParam.testRatio = 15/100;  % Train the Network [net, tr] = train(net,inputs,targets);   Here are the ann training results:  Here is the regression plot:   Here is the actual output (green) and neural network output (red) charts in one diagram:    As it can be seen the charts are not overlapping. This means that network has not worked well.  How can I improve results? Should I use other network or topology. Is my data very noisy or incorrect or they are less to train ann? I've taken data from here:


Table with 100 % width and vertical / horizontal alignment

I want to draw the following table in LaTeX. In the first column the text should be left aligned. The text in all other cells should be centered. The first problem occurs with D in the first row. If I write a \centering in front of D, I get a LaTeX error. The second problem is, that I want to vertically align the text in all cells but I don't know how. I have found a solution but it doesn't work if the width of the first column is specified.  \documentclass{article} \usepackage{blindtext} \usepackage{tabularx}  \begin{document}   \begin{tabularx}{\textwidth}{|p{4cm}|X|X|X|X|}     \hline                & \centering A & \centering B & \centering C & D\\     \hline     \blindtext & 123 & 123 & 123 & 123\\     \hline   \end{tabularx} \end{document}


What is the value of Ricci scalar at $r=0$ inside Black Hole? Since $R_{\mu \nu}=0$ is vacuum solution and valid outside event Horizon of black hole where there is no mass energy density. But inside black hole at $r=0$ what is the value of Ricci scalar, where $T_{\mu\nu}\neq 0$.  At this point geometry blow up (having infinite curvature) and Kretschmann scalar have value $K=\frac{48 G^2 M^2 }{r^6}$.


Can I download a server world and build on it locally?

I have an 'online' Minecraft server that I have been building on for the past couple of months. There are some big edits that I want to make on the map, but the server only has 512mb of RAM so it crashes.   My question is, is it possible to download the world from the server so that I can load it up on my computer locally and run it in single player to make large edits? I would later hope to re-upload the map onto the server after I finish making changes.


click function not working as expected on dynamically created elements Jquery

I have list of dynamic created elements which when clicked fires a ajax request and displays the result. The problem is it works only when it is clicked twice. The first click on element doesn't work. Whereas the second click works perfectly. I don't understand the reason behind this. I did try unbind() but it didn't help   $("#profiles_name ul a").on('click',function(event){         $.ajax({    }   });   });.   I did try $("#profiles_name ul a").unbind().on('click',function(event).. It didnt work still.   Here is my dynamically created tag

Frontend Dev

   Also to keep in note that, For example if i have two dynamically created list, When i click on list 1(first time) it doesnt work list 1( second time) works. After page refresh,  click on list 1(first time) doesn't work and click on list 2 (first time) works. i.e First click doesnt work irrespective of the dynamically created element.


$ echo $(( 255 )) 255 $ echo $(( 33 )) 33 $ echo $(( ~33 )) -34 $ echo $(( ~255 )) -256 $    and my kernel is:  $ uname -a Linux HOSTNAME 3.2.0-40-generic-pae #64-Ubuntu SMP Mon Mar 25 21:44:41 UTC 2013 i686 i686 i386 GNU/Linux     QUESTION: ~ is for negating the number AFAIK. But why does ~33 produce -34 and why does ~255 produce -256?


Ubuntu 18.04.5: cannot load module for Intel Wifi adapter

I'm running an Acer notebook that comes with an Intel WiFi adapter. The included kernel does not support it natively, so I found some separate  drivers which are installed via dkms. Unfortunately when calling modprobe iwlwifi  an error modprobe: ERROR: could not insert 'iwlwifi': Required key not available  is returned. I already found a solution to disable scure boot via mokutil, but this does not work for me here - when I do this, loading of the kernel fails at grub boot level and I can't get into it at all. So...how can I fix that, how can I get my 18.04.5 working with the Wi-Fi 6 AX200 chip? Thanks! UPDATE: to all the "I'm so clever in closing questions"-people: my question was NOT answered somewhere else. The solution you linked to suggested to disable secure boot - which doesn't works with newer BIOS versions. Disabling secure boot via MOK prevents Ubuntu from booting at all. So thanks for closing this question while not understanding what really is going on!


High performance, high availability backend configuration

We have a mobile app project which at this moment gets very low traffic (few server hits per day) but due to potential cooperation with a big company we might soon start serving as much as 500.000 customers per month.  Our backend services are hosted at DigitalOcean (and we'd like to keep it that way as much as possible) and we have CloudFlare (free version) in front which also handles DNS and other related stuff.  The backend service is divided into 5 Node.js apps: api (serving data from the database), cdn (serving images), cms (admin content management), shared_modules (codebase shared between 4 other apps) and www (landing page for the mobile app). Currently all 5 apps are being "dockerized" within one DO droplet (Dokku-based image, the cheapest $5/mo droplet).  The most important apps are api and cdn which must always be available because they're the backbone of our mobile app.   I do understand that at least each app should get its own droplet but it's obvious that won't be enough to serve so many customers. Ideal solution would let us spin additional droplets per-request basis without much additional configuration to do so.   While I'm also aware that app optimization plays a major role when it comes to high-performance setup, at this moment I'm more interested in the server architecture aspect.  My question is what would be the most reliable (and also the cheapest) server architecture setup which would be able to serve so many customers per month?  EDIT: I disagree this question is related to the linked question simply because I'm providing specific information (numbers, technologies/services used) and I'm looking for specific solutions (the exact server-side architecture to handle high availability, high performance requirements in my case). The linked question is related to high availability, high performance in general or theory (which might be sufficient for writing a thesis) but it is NOT what I'm looking for. The linked question DOES NOT answer my question at all. If I were to look for "dry" information on high availability, high performance then I would go through Wikipedia and not ServerFault. In light of everything said I'd kindly ask you unlock this question because I'm not getting my answer from the linked question. Thanks.


Can you help me paint the hall this weekend?    Can you help me to paint the hall this weekend?      Do we add "to" the second verb (paint) because it's in the infinitive?


Set a cookie whenever front page is viewed

I run  (currently 7.15) since longer time and have the problem with cookies:  I need 2 cookies for non-Drupal PHP-scripts at my web site.  I set them in the hook_init of my custom module:  /**  * Implements hook_user_login().  */ function pref_user_login(&$edit, $account) {     if ($account->uid <= 0) {       return;     }      #drupal_set_message('
Hello, '.$account->name.'
');     $auth  = md5(join('_', array($account->uid, MY_SECRET)));     $year  = time() + 60 * 60 * 24 * 30 * 12;     setcookie('pref_id', $account->uid, $year, '/', '.preferans.de');     setcookie('pref_auth', $auth, $year, '/', '.preferans.de'); }   The problem is, that I need to set the both cookies each time a logged in user visits the front page and not just when the user logs in.  Does anybody please have an idea how to do it, maybe by JavaScript if I can't do it regular way?


Need Title of Sci-Fi Space movie - Girl escapes space prison-ship and lands on Earth

I recall seeing the start of this movie during the early 1990s.  Action takes on a sort of space prison-ship. Prisoners have shaved heads, all dressed in light suits. The guards are wearing sorts of headsets - presumably to protect them from the psychic powers of the prisoners.  There is a bit of "romance" between two of the guards - (a guy and a girl). The guy takes off his headset, the girl insists he puts it back, he insist on having a kiss, she rejects him and goes about her business. He's upset by this and lingers around. The prisoners then use their psychic powers to make him a bit sick and weary - he slumbers around and opens doors of the prisoner cells. The prisoners crawl out. Other guards sound the alarm and shoot at the prisoners, but are overwhelmed.  Prisoners crawl to some sort of central gate and try to open it. The girl from the previous scene escapes the spaceship in a shuttle and lands on Earth - there she is rescued by a nerdy guy. Because she's unaware of Earth morality, she undresses in front of him before having a bath.  The movie had somehow decent visuals and effects, more style, more like Lucas THX 1138 - minimal but with style.


Does a 240v water heater circuit require a neutral?

I am confused something. I want to install a tankless water heater. Mounting the device, the plumbing, wiring, routing to the 200amp panel is all easy and straight forward. Where I get stumped is the two breakers. 75A (2x40)A 240 8 AWG The directions show to run 2 8/2 with ground. The Illustrations show to connect both black(hot) and white(N) to the two prongs on the breaker. I totally get 240v using a black red and white. but 240 connecting the Neutral to a hot I do not get. I guessing something like a dryer really is has two components using 120v each sharing a nuetral and we call it a 240v. But true 240v is doubling up on the hot but what about the neutral? If anyone can explain this I'd appreciate it. UPDATE Thanks for all the comments but seriously guys, getting all hung up on the "White is just a color" is odd. I know a white wire is a wire. So when you connect a wire to the hot and another wire to the neutral (in this case they are (pink and blue) on the panel. Then connect the other ends of these 2 wires to a 120v outlet. The current being AC travels in alternating directions on this pair of wires. So if I instead connect both of these wires to hot and connect the other ends to lets say one of the heating chambers of a tankless water heater. I got lost on how the alternating current occurs the same on 2 hots rather that a hot and a neutral. That my question. I am not asking how the current knows it's on a pink wire.


The Markdown rendering on deleted content should be disabled or reduced

Deleted content, including content that is deleted via spam and rude/abusive flags is still visible to users with enough reputation (generally 10k+, I believe). I think the Markdown rendering of this content should be changed so that links are not "active" and images are not displayed. Ideally, the Markdown render would vary based on how the post was deleted such that content that was deleted as spam would have no active links and rude/abusive content would have no images. From a practical standpoint, just turning the Markdown rendering off for deleted content would be enough.  For example, on a site I am a moderator on, we have a user who is spamming/abusing the site with NSFW images. Our users are rapidly flagging, downvoting, and deleting the content and the site moderators are on top of the issue. I am hoping at some point the community managers (CMs) will purge our list of NSFW posts. Until that happens, a bunch of the posts on our front page are not safe for high rep users (those who can see deleted content) to view while at work.  It seems the system try to hide the content from high rep users if it has been flagged, however, mods are still presented with the content. If a high rep user wants to interact with a deleted post they would eventually have to look at the content. Further, users do not always flag and delete in the best possible way. By turning off the Markdown renderer users would be "safer".