Diffie-Hellman key exchange: Why is $(g^{k_1} \bmod n )^{k_2} \bmod n \equiv (g^{k_2} \mod n)^{k_1} \bmod n$

In a Diffie-Hellman key exchange, with a generator $g$ and a modulo $n$, and two keys $k_1$ and $k_2$, why is   $(g^{k_1} \bmod n )^{k_2} \bmod n \equiv (g^{k_2} \mod n)^{k_1} \bmod n$


Access denied to a folder after removing administrator permission

I wanted to encrypt a specific folder in my company domain and now I cannot access it.  This is Windows 7, I am administrator on of my PC.  On the folder I did right click->properties->security  for the System and Administrators I did Deny all. and for me (DOMAIN\ME) I gave full control.  Now I cannot access the folder. I tried to set the permissions back, but with no success


I made a small animation. Very simple, just a floating cube and a color changing light. After fighting a bit with key frames it was time to render, I realized I have no idea how to export this. How do I export the video?


Is it the right way to use present continuous when talking about the future?

Some  say   Sometimes, speakers use the Present Continuous to indicate  that something will or will not happen in the near future.  Examples:  I am meeting some friends after work. I am not going to the party tonight. Is he visiting his parents next weekend? Isn't he coming with us tonight?    say:  The present continuous is used to talk about arrangements for  events at a time later than now.  There is a suggestion that more than one person is  aware of the event, and that some preparation has already happened. e.g.  I'm meeting Jim at the airport = Jim and I have discussed this. I am leaving tomorrow. = I've already bought my train ticket. We're having a staff meeting next Monday = all members of staff have been told about it.   I think the second one makes more senses.  But my question is that:  Is present continuous tense only used for future arrangements? & If there is no future arrangement then we can not use present continuous tense right?  See this example,  "I am seeing my mom this afternoon" could mean "My mom & I have agreed to meet each other before"  "I am going to see my mom this afternoon" could mean "I've got a plan to see my mom, but my mom may not know it she & I have not arranged a meeting yet"   "I will see my mom this afternoon": "Will" in this case expresses a Voluntary Action. I'm willing to see my mom.  "I am going to the beach this afternoon" could mean I agreed with myself that I am going to go to the beach this afternoon & I prepared stuffs (swimming suits, sun scream, etc) for that.


Need help in recording mutual funds on tax returns

If I record the proceeds and costs of all short term and long term mutual fund transactions, why are there additional capital gain distributions?  It seems like double taxation.


Intuition for why sum of gaussian RVs is different from gaussian mixture

I know that in the case of Gaussian mixture, the "intuition" is that you're drawing from a PDF which itself is just a sum of weighted Gaussian PDFs.  I don't understand the intuition behind how the sum of two iid Gaussian RVs leads to a Gaussian RV. I know the maths behind it, but I'm having a hard time visualizing how the sum of two Gaussian RVs leads to a Gaussian RV (and not a mixture).


Why do we multiply the magnetic flux by the winding number?

A current I flows through a solenoid (with n turns). Self inductance is $L$. If the magnetic flux is $\phi$, I am taught that $-n\phi=LI$  I dont understand the part with $n$, why do we have multiply by $n$? $\phi$ itself represents the whole magnetic flux there, if $\phi$ implied the flux only occurred by one coil, then it would be correct.   Moreover, flux change by a coil ($n$ turns) in $dt$ time is $d\phi$, so the induced electromagnetic force is   $$dE=n \cdot \frac{d\phi}{dt}$$   Why do we multiply by $n$ here? If $\phi$ means the whole flux, then why multiply?


Ubuntu's C drive or system drive partition isn't showing

I've installed Ubuntu by watching a tutorial from internet. I had already dual booted Windows 7 and windows 10. so, I decided to install Ubuntu in the windows 10 drive to replace it with Ubuntu. So, I did it.Now when I start my computer it shows 4 menus from which I can select between Ubuntu and windows. But when I start my windows 7 and go to my computer I cannot see that partition/drive (i,e one of my partition that i used for installing Ubuntu isn't accessible from my windows 7). Now I want to uninstall my Ubuntu and want to get back that partition for using it to store my data or something else. please help me.


I've linked scilab to gnome application menu (by creating a *.desktop file) but it's closed immediately when I run it from menu

I have downloaded scilab and extracted it to /home/user/apps/scilab-6.0.1/. There isn't any problem executing from command line and scilab runs perfect after I type the following command:  ~/user/apps/scilab-6.0.1/bin/scilab   To link scilab to the gnome application menu and favorite apps, I've created the following scilab.desktop file in the path /usr/share/applications/:  [Desktop Entry] Comment=Scientific software package for numerical computations Exec=/home/user/apps/scilab-6.0.1/bin/scilab %f GenericName=Scientific Software Package Icon=/home/user/apps/scilab-6.0.1/share/icons/hicolor/256x256/apps/scilab.png Name=Scilab StartupNotify=false Terminal=false Type=Application Categories=Science;Math;   The scilab icon appeared in the menu as a result, but when I click on it, it opens and closes immediately. What should I do to solve this problem?


What are the minimum content and traffic requirements for Google AdSense?

I have a blog which is only 35 days old. What are the requirements for Google AdSense?  How many page views are required and how old does the site have to be?


Is it legal to clone a character from other game?

Is it legal to make a character very similar/exact from other game? E.g. take characters from Team Fortress 2 game, remake them in pixel art and use it in my game, but just change their names(with an intent to make money).  Would I get in trouble?


Given two points "A" and "B" outside of a given circle of center "O". Where is the point X on the circle, such that AX + XB is the shortest possible?  For the problem "Given two points "A" and "B" on the same side of a given line. Where is the point X on the line, such that AX + XB is the shortest possible", there is that trick of reflecting one of the points about the given line, let's say the point A, and then the point X is the intersection of the line A'B with the given line. But I did not find a way of using that trick to this variation that changes the line for a circle...  Is there a way of solving the problem without long calculations? Something like the trick for the points and a straight line?


I have created the following code to open a .pdf file from the root directory of my installed program.  private void HelpButton_Click(object sender, RoutedEventArgs e) {     System.Diagnostics.Process proc = new System.Diagnostics.Process();     proc.EnableRaisingEvents = false;     proc.StartInfo.FileName = "Help Me.pdf";     proc.Start(); }   The problem is that the program, once installed and started from the desktop icon, will not open the .pdf file.  However, when started from the actual file that the desktop shortcut is pointing to, the button opens the file just fine.  I have also tried the following with the same effect.  private void HelpButton_Click(object sender, RoutedEventArgs e) {     ProcessStartInfo helpInfo = new ProcessStartInfo("Help Me.pdf");     helpInfo.WorkingDirectory = Assembly.GetExecutingAssembly().ToString();     Process.Start(helpInfo); }  private void HelpButton_Click(object sender, RoutedEventArgs e) {     ProcessStartInfo helpInfo = new ProcessStartInfo("Help Me.pdf");     Process.Start(helpInfo); }   private void HelpButton_Click(object sender, RoutedEventArgs e) {     System.Diagnostics.Process.Start("Help Me.pdf"); }   Any help would be greatly appreciated


I want to solidify my understanding of the "coding to interface" concept. As I understand it, one creates interfaces to delineate expected functionality, and then implements these "contracts" in concrete classes. To use the interface one can simply call the methods on an instance of the concrete class.  The obvious benefit is knowing of the functionality provided by the concrete class, irrespective of its specific implementation.   Based on the above:    Are there any fallacies in my understanding of "coding to interfaces"? Are there any benefits of coding to interfaces that I missed?   Thanks.


Derivation of the formula for Ordinary Least Squares Linear Regression

How was the formula for Ordinary Least Squares Linear Regression arrived at?  Note I am not only looking for the proof, but also the derivation. Where did the formula come from?


Let A be a right R-module. Suppose for every  left ideal J of R, the homomorphism $f:A\otimes J\to A$ defined by $f(x\otimes y)=xy$ is injective, then A is a flat R-module.(the identity 1 is in R)  I found the result in my book but didn't give me the proof, and I felt very confused about it! Can someone tell me how to prove it?


Thumb-drive (USB) not detected after formatting

After formatting my USB thumb-drive (16 GB) is not detectable on my Ubuntu 20.04 (Linux) pc - it (the thumb-drive) was fine before the formatting). Neither the 'Disks' utility nor 'GParted' detect it. It is not detected when using Terminal commands: $ lsblk     $ sudo fdisk -l My pc is Ubuntu 20.04 but I also have a Windows 10 laptop.


Is there a way to make particles behave like rigid body objects?

I want to create a scene that has a lot of irregularly shaped objects piled up on the ground.  I don't want the objects to intersect with eachother.  I started off by creating a particle system that uses an object group containing these objects.  No matter what settings I 'messed with' I could not get the individual objects to behave the way I want them to - They would interact with the ground like perfect spheres, and they would pass through the other particle objects.  Is there a way to make particles have rigid body physics so they behave with each other and with the ground like real objects?  Or failing that - is there a way to copy rigid body attributes to many objects? (i.e. plan be - don't use a particle system, but rather make lots and lots of copies of the objects and just let them fall)  Edit:  I ended up applying the settings 26 times (there are 26 unique objects) and then copying those 26 objects several times. To produce this    but this was before there were any replies to this question. Thanks to WChargin's answer I will be able to copy the attibutes in one action next time I do something like this :)


Questions:   Why are the top corners of this number line missing? Why aren't the bottom corners or any other corners of this number line missing? How do I ensure the corners are always there?     \documentclass{article}  \usepackage[left=1.5cm,right=1.5cm,top=2cm,bottom=2cm]{geometry} \usepackage{tikz}   \begin{document}  \begin{tikzpicture}[line width=0.08cm]  \draw (0,0)--(5,0); \draw (0,0.3)--(5,0.3);  \foreach \x in {0,...,5}  {  \node at (\x,-0.55) {\x};  \draw (\x,-0.3)--(\x,0.3);  }  \foreach \x in {0,...,5}  \draw (\x,0)--(\x,0.3);  \end{tikzpicture}  \end{document}   That code yields this:


I am developing this site here: bottlesbeach.eu Now I'm trying to center the profile picture avatar inside the navbar:  I tried to use: vertical-align: middle  But as you can see from the image, my avatar continues to remain anchored at the top. Do you have any ideas to solve this? Navbar:   .avatar {   vertical-align: middle;   width: 30px;   height: 30px;   border-radius: 50%;   float: right;   vertical-align: middle; }
    Send a Bottle   Bottles   Chat   About   Donate   Log-in


Is it possible to Idle, and get trading cards?

In order to receive Steam Trading Cards, you must play a game for some period of time. Is it possible to keep the game open as you go run errands, and have the cards when you get back, or do you have to be actively playing the game to receive cards?


Let $G$ be a matrix Lie group. Its Lie algebra $\mathfrak{g}$ comes equipped with a symmetric (2,0) tensor known as its Killing from, denoted $K$ and defined by  $$ K(X,Y) = -\text{Tr}(\text{ad}_X \circ \text{ad}_Y)$$  where $\text{ad}_X \in \text{GL}(\mathfrak{g})$ defined by $\text{ad}_X(Y)= [X,Y]$. Show that $K$ is Ad-invariant, in the sense that  $$  K(\text{Ad}_A(X), \text{Ad}_A(Y)) = K(X,Y) \quad \forall X,Y \in \mathfrak{g}, A \in G $$.  Here $\text{Ad}_A(X) = AXA^{-1} \in \mathfrak{g}$.   I suppose that it suffices to prove it on a basis, but it isn't a big deal to let $X$ and $Y$ be arbitrary. Choosing a basis $E_j$ for $\mathfrak{g}$, I write $$ [E_j,E_k] = {c_{jk}}^l E_l $$ $$ X = a^kE_k, Y = b^kE_k $$ and  $$ AE_kA^{-1} = {d_k}^lE_l. $$ Then $$ [X,[Y,E_m]] = [a^kE_k,[b^lE_l,E_m]] = a^kb^l {c_{kn}}^j {c_{lm}}^n E_j$$ and so the trace of this operator is $a^kb^l{c_{kn}}^j{c_{lj}}^n$. The left hand side is $$  [AXA^{-1},[AYA^{-1},E_m]] = [a^k{d_k}^lE_l,[b^n {d_n}^j E_j,E_m]]= a^kb^n{d_k}^l{d_n}^j {c_{jm}}^r {c_{lr}}^k E_k$$ so the trace of this operator is $$ a^kb^n{d_n}^j{d_k}^l{c_{jk}}^r{c_{lr}}^k $$  assuming the indices are correct. Now these two have to be the same somehow. Using that $\text{Ad}_A{[X,Y]}=[\text{Ad}_A{X}, \text{Ad}_A{Y}]$ may be promising, but I haven't found anything useful with it. A hint would be appreciated.


Should I write:     To gain insight on this obstacle, she will begin to analyse . . .    or     To gain insight into this obstacle, she will begin to analyse . . .   Google shows (much) more results for "into" than for "on".


Why is it considered bad to expose List?

According to FXCop, List should not be exposed in an API object model.  Why is this considered bad practice?


Is it more Java-thonic to throw an exception or return null?

I have an unfortunate Java library that I've inherited that parses JSON.  Right now, if you ask for a key that doesn't exist in a JSON array, it dies with a null pointer.  I'm going to edit the library to do something more reasonable.  I think I have two options:  1) Return null so the caller can check  2) Throw a more explicit exception (more descriptive than "Null Pointer"), forcing the caller to handle the case where they asked for a non-existent key.  I come from a python background and am strongly drawn to number 2, seeing as it will ensure that some bonehead can't call this function and then continue on with a null value, crashing their application later on and possibly corrupting data.  Which way do YOU think is more in line with best practices of Java?  This is not a duplicate of other language-independent questions on the same topic.  This is specifically in the context of Java!!!!


Problem:Let $k$ be an odd positive integer. Prove that $(1+2+3...+n)|(1^k+2^k+3^k+...+n^k)$ for all positive integers $n$.  My Attempt: Proof (By Induction on $k$): Let $P(k)$ be the proposition that $(1+2+3...+n)|(1^k+2^k+3^k+...+n^k)$ for all positive integers $n$ when $k$ is odd. Then $P(1)$ and $P(3)$ are trivially true. So for $k\geq 5$, we assume that $P(k)$ holds. We would like to show that $P(k+2)$ also holds. In order to do that consider the following sums  $$1^{2}(1^k+2^k+3^k+...+n^k)=1^{k+2}+2^k+3^k+...+n^k$$ $$2^{2}(1^k+2^k+3^k+...+n^k)=2^2*1^k+2^{k+2}+2^2*3^k+...+2^2*n^k$$ $$..$$ $$n^2(1^k+2^k+3^k+...+n^k)=n^2*1^k+n^2*2^k+n^2*3^k+...+n^{k+2}$$ Note that $$1^2(1^k+2^k+3^k+...+n^k)+2^2(1^k+2^k+3^k+...+n^k)+...+n^2(1^k+2^k+3^k+...+n^k)\equiv 0\pmod {\frac{n(n+1)}{2}}$$  Therefore, if we denote $\sum_{i=1}^{n}i^2=s$, then    $(t)(1^k+2^k+3^k+...+n^k)-t+\sum_{i=1}^{n}i^{k+2}\equiv 0\pmod {\frac{n(n+1)}{2}}$ which implies that $P(k+2)$ holds. Hence by PMI we are done.  Now I am a bit hesitant in convincing myself whether this proof is correct or not. This is because I have never seen induction performed in this manner. Any reasons as to why this argument falls would be much appreciated.


Is there any way I can clear the X clipboard from a cron job? The usual commands for xclip don't seem to work.  echo -n | xclip -selection clipboard   doesn't work from cron.


Ancient statues actually slow-moving creatures, classroom short story from <= 1980

There's been a couple of questions lately about different creatures/rocks/trees that are living at a different time-rate than humans, and it got me thinking about a story that I'd read when I was in 6th grade and hoping to find again.  I read the story in English, in the US, in 1980. Here's where it gets tricky... the story was actually on a card, maybe 6" x 8", with a small illustration on each side. It was in a teacher's box with many other cards (different stories) in a classroom. We were assigned to read a story/card once a week or so and there might have been questions about the story on the card itself, or we might have just had to note that we read it. I don't think that all the rest of the stories were necessarily Sci-Fi, just short stories to get the attention of a 6th grader. I do not remember any of the other stories.  The story itself was short, as I said, maybe 2 pages (card sides) long, and illustrated with 1 or 2 drawings of 2 large (maybe 30-50') statues that vaguely resembled Easter Island statues but had arms and legs. One statue was sitting/laying on the ground, and the other was standing nearby. There had been pictures of the statues taken quite a few years previously, and a person was in a small plane taking more pictures now. Comparing the pictures it was noticed that the statues were slightly moved (the standing one's hand had moved closer to what appeared to be a gun on it's hip), and it was determined that they weren't statues but rather creatures who lived at a much slower time rate than humans, and that the standing one was coming to the defense of the fallen one.  Does this sound familiar to anybody?


After MacOS High Sierra install, localhost fails and apache has syntax errors

After upgrading to MacOS High Sierra, I haven't been able to access my localhost. I tried restarting Apache, but it still didn't work. So I did apachectl configtest and got this error message:     httpd: Syntax error on line 544 of /private/etc/apache2/httpd.conf:   Syntax error on line 8 of /private/etc/apache2/other/+php-osx.conf:   Cannot load /usr/local/php5/libphp5.so into server:   dlopen(/usr/local/php5/libphp5.so, 10): Symbol not found: _environ\n    Referenced from: /usr/local/php5/libphp5.so\n  Expected in:   /usr/sbin/httpd\n   Line 544 of my httpd.conf file is Include /private/etc/apache2/other/*.conf  The +php-osx.conf is an alias to entropy-php.conf, and line 8 of that file is LoadModule php5_module        /usr/local/php5/libphp5.so  The remaining lines of entropy-php.conf are: LoadModule php5_module /usr/local/php5/libphp5.so  <IfModule mod_php5.c>      AddType application/x-httpd-php .php     AddType application/x-httpd-php-source .phps      <IfModule mod_dir.c>         DirectoryIndex index.html index.php     </IfModule>  </IfModule>   I am using Apache/2.4.28 (Unix) and PHP 5.6.30.  Everything was working fine until the update. I have searched online for any solution this issue, but to no avail. Someone posted a similar question here a couple of years ago regarding the same syntax error, however, he didn't provide enough details or any follow-up regarding his setup, and no solution could be offered:


I've read  that in order to create a file inside a directory in Linux, one should have write permission to that directory. However when examining this (in Ubuntu Server 14) it did not worked.  osboxes@osboxes:~$ mkdir mydir  osboxes@osboxes:~$ chmod 200 mydir  osboxes@osboxes:~$ ls -l d-w------- 2 osboxes osboxes 4096 May 25 09:52 mydir  osboxes@osboxes:~$ touch mydir/myfile touch: cannot touch 'mydir/myfile': Permission denied   only after adding execute permissionto mydir I could touch that file. So execute permissions are also needed in order to touch a file?  EDIT: from @Pablo Bianchi  I learn that      Write (w)      The ability to rename files in the directory, create new files, or   delete existing files, if you also have Execute permissions. If you   don't have execute perms, then write perms are meaningless."   So I guess that execute perms are ndeed required in order to use write perms to create new files.


Here's my question, it is rather straightforward: does $\sum_{n=0}^{\infty} \frac{(n+1)(n+2)}{2^n}=16$? First I tested if $\sum_{n=0}^{\infty} \frac{(n+1)(n+2)}{2^n}$ diverges to make sure it doesn't add to $\infty$. I found that taking the limit of the series as n approaches $\infty$ gives no information. Then I expanded the series to get $\frac{2}{1}+\frac{6}{2}+\frac{12}{4}+....$ and found no pattern. My goal is to evaluate the series and find out if it's equal to 16 or not. How should I do that? or is there another approach to the question?


How to subtract n days from current date in java?

I want to subtract n days from the current date in Java.  How do I do that?


Let $G$ be a finite group and $H \leq G$, $K \leq G$. For an element $g \in G$, prove $$|H|[K:K \cap (g^{-1}Hg)]=|K|[H:H \cap (gKg^{-1})].$$  I am not sure where to start proving this. A hint would be helpful please.


Is the length of ethernet frame fixed between different media?

According to wikipedia, ethernet frame is 1522 bytes long.  However, in wireshark's wiki, it seems it is not always true:       As the Ethernet hardware filters the preamble, it is not given to Wireshark or any other application. Most Ethernet interfaces also either don't supply the FCS to Wireshark or other applications, or aren't configured by their driver to do so; therefore, Wireshark will typically only be given the green fields, although on some platforms, with some interfaces, the FCS will be supplied on incoming packets.     Questions: 1. Is the length of ethernet fixed between all hardware? 2. How to know the length of ethernet frames in linux?


Calculate circle's offset given distorted ellipse, when projected onto a sphere

I have a circle moving on a spherical surface. If the camera angle is fixed, is there a way to calculate the original circle's offset from the centre given the distorted ellipse formed when the circle moves to the edge of the sphere(as seen from the camera)? I've looked into Listing's plane and the Tissot directrix(because I'm working with eyeball rotation), but neither seems to provide a clear solution to this. I've also looked papers regarding eyeball roation but they seem to focus on the physiological aspects rather than the math of the movement. In other words: In the picture above, given one of the outer nine images as well as the middle one, I want to calculate how much the circle(i.e. iris) has moved/rotated from its position in the middle picture. I assume it has to do with comparing the distorted ellipse with the circle, but I can't seem to find out how. Is there some formula for this?


EDIT: Here's the project file:    I followed Blender Guru's tutorial for making an animated flag, and everything seemed like it was working fine. I even walked away from the render last night seeing each frame rendering with all the materials intact.  I wake up to this:    In 3D view, when I go to rendered shading mode, it looks correct:    But if I actually render it, the materials disappear:    Why is this??  I used the Import Images as Planes add-on for the flag texture, so I'm under the impression from the tutorial that UV mapping is not necessary, but anyway, the regular glossy textures of the metal flagpole and Suzanne head are also disappearing.  I googled and searched, but this doesn't seem to be the same as any problem I've seen anyone else post about. What am I doing wrong?  Thanks in advance!


Ability to mark dated answers as deprecated

It is common while reading posts on the site to come across answers that are several years old and contain deprecated code.  Currently, there is not a visible indicator that warns viewers that code is deprecated.  Would it be possible to include some type of icon or note at the top of answers to quickly indicate to viewers that code is deprecated?


What kind of recommendations do you have for a very good source to learn Galois Theory? Is there any Atiyah-MacDonald-type book on Galois theory? What is your opinion on the chapters from Lang, and Dummit and Foote?


What happens when when casting an int to unsigned int in C?

I have:  int i = -INT32_MIN unsigned int ui = (unsigned int)i   What will happen when I cast the int to an unsigned int?   What are the rules for casting? Is casting safe? Will casting always produce a predictable value?


Is correcting a common misspelling too minor an edit?

I've come across a fellow that is apparently trawling SO looking for the common "calender" misspelling and correcting instances to "calendar."  He often does only that... leaving things like "Thanks" and "Regards, JoeBob" in the questions.  Should edits such as his be rejected as too minor in review?  See also a proposed spelling edit on a  that was closed as NARQ hours ago.


I want to rid this  of mine. Since it is put on hold, I can not delete it. No need of showing it, so I am suggesting that even if the questions are on hold, a user having the ability to delete his questions is more friendly.


Can players in 5e ready an action before combat begins? If so, does this impose any penalties?  (, but it is written for 4e and IMO the answer left something to be desired)


Does there exist a universal formula of first-order logic that is satisfiable only by structures with infinite domains?

Following up this question - :  Does there exist a universal sentence $A:=\forall x_1 \dots \forall x_n \varphi(x_1 ,\dots ,x_n )$ (where $\varphi$ does not contain quantifiers) that is satisfiable but not in finite models (i.e. only in infinite models)?


Biblatex, How to make Author First name to be short for Harvard Referencing?

For example:  @book{cohen2013statistical,   title={Statistical power analysis for the behavioral sciences},   author={Cohen, Jacob},   year={1988},   publisher={Routledge},   edition = {2} }   Outcome:    It suppose to be:  Cohen, J., 2013. Statistical power analysis for the behavioral sciences. Routledge.   where the first name become short Cohen, J.


How can I ger a line break after the label of a description environment item? I'd like to keep the indentation and the bold face for the item label, but I'd like to have the body of the item in a separate paragraph, because it starts with an itemize environment and indenting that looks really strange.  Adding \\ does not work (error message “no line to end here”), neither does a blank line or \par (no effect). Even \,\par has no effect.  Example:  \documentclass{article} \begin{document}  \begin{description} \item[Animals:]   \begin{itemize}   \item Dog   \item Cat   \item Fish   \end{itemize} \item[Colors:]   \begin{itemize}   \item Red   \item Green   \item Blue   \end{itemize} \end{description} \end{document}   It renders like this:


Why are upvotes and downvotes locked after 5 minutes?

5 minutes after voting a lock is placed on votes for the question/answer. A user can only recast his/her vote if the post is edited.  So my question is    Why is there a locking mechanism on question/answers? Should the locking time be increased to 10 min OR 15 min?


Do I have to remove the old thinset before installing new tile?

I will be installing some new 12x12 tiles in two bathrooms approx 25 sq/ft each. When I pulled up the old tiles, there was no thin set that had made contact with them so the removal was very easy. Now, the thin set on the floor is a different story. I have been chipping away at it by hand in one bathroom to get to the cement floor below and it has been a bugger to get off. Before I attempt to continue this process in the second bathroom, I would like to know if it is absolutely required to do so if it is well adhered to the cement underneath?  (It's my hope, obviously, that I can tile over the old thin set as long as it is level and firmly attached.)  EDIT: My subfloor is a concrete slab with the thin set on it. It must be chipped away to remove vs. cut and replace sub floor.


The calculation in cell I15 should result in 0 but instead it is 0,0000000000000000004336808.... Any idea why this happens? The calculation is pretty simple, just 0,00125574 - 0,00125574 Below is the sheet that I'm referring to:


Many things have glow in the dark properties (glow sticks, paint, toys ..), and I am wondering what is the physics behind them. How do these materials store light energy and emit it later when dark?  What dictates the wavelength(s) of the glow? Is there a limit on how much energy can be stored and recovered in these materials? Do they give out heat as well as light?


Transform data type EWKT and GeoJSON to SRID 900913


how to recover password android with permission denied?

I get the following message:  adb: error: failed to copy '/data/misc/wifi/wpa_supplicant.conf' to '.\wpa_suppl icant.conf': remote Permission denied   I can not copy nothing from my android to recover my password of mi wifi


How to calculate such sums of Legendre symbols?

How to calculate such sums as $\sum_{x\in\mathbb{F}_p} \left(\frac{x^2+ax+b}{p} \right)$  If $x^2+ax+b$has a root, $b$ may be eliminated and the sum is evaluated to be $0+\sum_{x\in\mathbb{F}_p^*} \left(\frac{1+ax^{-1}}{p} \right)=-1$. Otherwise to linearize it, you need to go into quadratic extensions. So I guess there may be a solution resorting to extensions of $\mathbb{F}_p$.  It is easy to extend the symbol since the extension is cyclic. But then I need to sum in an unfamiliar space. Can we fix this and eventually give a proof in this flavor?  Any reference is welcome.


Why is the air in high atmosphere typically colder than on the ground?

The air at 10.000m altitude is mostly a lot colder than at the ground. Even if you are in the desert in temperatures of 40 degrees Celsius, the air above you will be significantly colder (below 0 degrees Celsius).  Considering that warm air is lighter than cold air, wouldn't one expect that the air on the surface of the earth is colder than in the atmosphere? Why doesn't the warm air just ascend while the cold air descends such that in the end the ground is cold while the high atmosphere is warm?  I suppose it has something to do with the pressure difference, but I can't figure out how exactly at the moment.


Do damage-over-time effects such as Melf's acid arrow or vitriolic blast stack with themselves?

I've seen many posts and discussions online that assume that the damage-over-time spell effects such as Melf's acid arrow (Player's Handbook) and vitriolic blast (Compete Arcane) self-stack, meaning that hitting a target with a second spell will deal additional damage each round. One warlock eldritch essence invocation, brimstone blast (CA), even has (poorly written) language presumably to specifically exclude itself from this capability.  However, stacking DoT spells might fly in the face of the rules for , specifically these two sections:     Same Effect More than Once in Different Strengths   In cases when two or more identical spells are operating in the same area or on the same target, but at different strengths, only the best one applies.      Same Effect with Differing Results   The same spell can sometimes produce varying effects if applied to the same recipient more than once. Usually the last spell in the series trumps the others. None of the previous spells are actually removed or dispelled, but their effects become irrelevant while the final spell in the series lasts.   This section would support that damage effects stack, since damage is not named as a special case (only bonuses/penalties):  From Player's Handbook page 171:     Spells or magical effects usually work as described, no matter how many other spells or magical effects happen to be operating in the same area or on the same recipient. Except in special cases, a spell does not affect the way another spell operates.   There is no mention of restrictions to damage -- all examples given for the section in the PHB relate to buffs and penalties except for the section regarding Instantaneous Effects:     Two or more spells with instantaneous durations work cumulatively when they affect the same target. For example, when two fireballs strike a same creature, the target must attempt a saving throw against each fireball and takes damage from each according to the saving throws’ results. If a creature receives two cure light wounds spells in a single round, both work normally.   This could be interpreted as saying that in all other cases, damage does not stack. However, the rest of the section deals with bonuses and penalties rather than damage, so fireball could just as easily have been a poor choice of example.  Here are some posts on other message boards implying that the damage effect from Melf's acid arrow and vitriolic blast are supposed to stack:       Multiple instances of Vitriolic Blast stack, so if you attack thrice with Eldritch Glaive, you'll do an extra 6d6 damage on the next round, and so on.        Vitriolic Blast seems to be a "must have" invocation to me. I haven't ever heard of a warlock that didn't get it or doesn't plan on getting it. It makes sense, being the only way a warlock can ignore SR and hurt golems. The automatic (no save), stacking extra 2d6 per round is pretty impressive as well. [emphasis added]        What stacking rules? This is no bonus or malus, it's simply damage.   The consensus from what I can find online seems to be that damage is not considered a bonus or penalty, and thus is not part of the stacking rules. However, the game seems to be unclear from what I can tell. All examples given for "can't do" are definitely not damage examples.  So the big question is: Do damage effects on a specific target stack?  This post is different from a  because it deals strictly with damage stacking and not bonus/penalty stacking. Damage stacking appears to possibly be a special or at least different case.


How is this polynomial reducible in $\mathbb{Z}[x]$

This question was asked in my abstract algebra quiz and professor gave answers  but my answer is wrong.  Question: Is $x^4+x^2 +1 =0$ irreducible in $\mathbb{Z}[x]$?  Root of $x^4+x^2 +1 =0$  doesn't exists in $\mathbb{Z}$ as it is always +ve and as $x^4+x^2 +1 =0$ is irreducible over $Z_2$ so it is irreducible over rationals and hence irreducible over integers. But answer is that it is reducible! Can you please tell what mistake I am making and what is right way to do?


JavaScript how to copy a data like the ctr+c in windows

I have a button on my website.  This button is called copy.  When the user clicks it, I want to have something be copied.  I already make the JavaScript function like this:  function copyToClipboardCrossbrowser(s, el) {}   where s is the data to be copied.  How please?  Thanks


Why is my object showing up in render image but not render animation

I'm not sure what went wrong, I have particles that I set as objects and they show up in render image but not render animation. I'm using cycles as the render engine. The actual objects do show up its just that the particles set as objects (more specifically a collection) does not show up. Any help would be greatly appreciated.


Prove that there is no rational lowest upper bound for $\sqrt{3}$.

I am trying to prove this and have looked at similar questions to gauge how to approach this. I have: Suppose that there exists a smallest rational number greater than $\sqrt{3}$. We shall call that number $n$, which, as it is rational, can be expressed as $\frac{p}{q}$ $\frac{\sqrt{3}+n}{\sqrt{3}}$ is a number greater than $\sqrt{3}$ but less than $n$, but this number would no longer be rational now, would it?


My players have been asking to improvise specific combat actions, mostly the archer wanting to aim at specific body parts. I haven't been able to find anything in the DMG or the PHB on the subject so I was wondering how I should deal with this.    How (if at all) should an attack roll be modified when targeting a specific body part? If there is not RAW on this I am open to playtested house rules per .


How to solve weird geometry when sculpting uv sphere?

FYI - I'm pretty new to blender. I'm playing around with the sculpting tools and was using the grab / inflate brushes on a UV sphere mesh that I had previously used a subsurf modifier on. It gets this weird spiky pattern near the poles and I can't really seem to smooth it out. Why does this happen and how can I fix it?


Let $\Omega$ be an open subset of C not containing $0$. Let $f$ be a complex valued continuous function on $\Omega$. Suppose $(f(z))^2=z^3$. Prove that f is holomorphic on $\Omega$.


Should "kenward-roger"/"satterthwaite" degrees of freedom be used with "GLMM" fitted with penalized quasilikelihood"?

Should kenward-roger degrees of freedom correction be used with generalized linear mixed models fitted with penalized quasilikelihood/"PQL"? There's no reason it isn't implementable but the question is whether this provides any advantage for making inferences.


I am writing a test case which I consider handling exception in it. I wrote it this way.  @Test public void myTest() {     int result = mymethod(a + b);     try{         assertEquals(1, result);     }catch(Exception e){         throw new RuntimeException();     }  }   Is this the write way? I am a little bit confused as I have not done this before.


Assume a coin has a probability p to get a head H. Suppose a coin is tossed until the partern T,T appear in the last 2 tosses. Once he got T,T then the game is finished. What is the expected number of flips is expected for the game?  I tried to find out the distribution of $N$ where $N$ stands for the expected value of the no. of tosses before getting T,T, but i don't know what kind of distribution is that, seems need another apporaches


Why is my table before the section title?

I would like to change the position of my table so that it is not before the title of the current section as show in my screenshot  .  Here is what I've tried so far:  \subsection{Cinétique d'oxydation des joints de grains avec teneur nominale en chrome}  La cinétique blah blah blah d'essai.  {\renewcommand{\arraystretch}{1.2} \begin{table} \centering \caption{Données utilisées pour la calibration de la cinétique d'oxydation des joints de grains présentant une teneur nominale en chrome à 320/325°C} \resizebox{\textwidth}{!}{     \begin{tabular}{|c|c|c|c|c|}     \hline \textbf{Repère} & \textbf{Échantillon} & \textbf{pox max (nm)} &     \textbf{Température (°C)} & \textbf{Temps (h)} \\     \hline     \hline B356 (TT 1h x 720°C) & 1816-22 & 10 & 325 & 0,16 \\     \hline T265 & 1866-20 & 307 & 325 & 100 \\     \hline B356 SA & 1866-187 & 847 & 320 & 1000 \\     \hline \end{tabular}  } \label{tab:calibrecinetique} \end{table}} \FloatBarrier  Sur la Figure   I have no idea why LaTeX always prints the table before the title, as I have enough place after (this is the beginning of the page). I've tried to use as for image the [H] to force the positionning, and also the FloatBarrier to force the cache of floating objects to be released (it would work if the table is printed ways after, which is not the case here).


How to write dashes in "a 2-4-room-apartment"?

I want to write in the announcement a description of an eventual apartment, which I am searching as a rental. I am interested in apartments with 2, 3, or 4 rooms. How should I write the compound adjective with numbers? With dashes or not — to indicate the range of rooms. If with dashes, should it be em or en dashes?  E.g.         a 2-to-4-room apartment?   a 2-4-room apartment?


After running an upgrade from Ubuntu 11.10 (Oneiric Ocelot) to 12.04LTS (Precise Pangolin), a window popped up saying that the upgrade failed and that I should run sudo dpkg --configure -a.  Running that command gave me:  sudo dpkg --configure -a dpkg: error: parsing file '/var/lib/dpkg/status' near line 55497 package 'indicator-displex':  blank line in value of field 'Description   Trying to run apt-get install -f gives me many dependency errors along with that same dpkg error.


Are there any specific advantages of using custom ROMs? I am using a stock ROM and removed all the bloatware. I tried few tweaks in build.prop and init.d and use greenify for better RAM and battery management. Other than the custom UI is there any real advantage of custom ROMs over stock ROMs?


Unable to find or create trash directory?

I am a user of Xubuntu and I have a problem with it. When I delete any files outside home they can't be deleted and instead of that, a message appears to me and says "Unable to find or create trash directory". I hope I find a solution for this problem, as I can't get rid of useless files. Thanks.


Bind change Event on dynamically added element

I have this html table:

    ID	    Sanity Check	    Result

    1	    <input name="sanityItem" size="20" maxlength="255" type="text">	    Not available yet

    2	    <input name="sanityItem" size="20" maxlength="255" type="text">	    Not available yet

   Whenever the user enters anything in input field I like to add new empty input field. This works fine with jQuery:  $("input[name='sanityItem']").change(function(){    var emptyRows = 0;    $("#sanityTestsTable tbody > tr td:nth-child(2) input").each(function(){        if ( $(this).val() == "" )           emptyRows++;     });          if ( emptyRows < 2 ) {       $("#sanityTestsTable tbody > tr").each(function(index){          if ( $(this).is($("#sanityTestsTable tbody > tr:last")) ) {             var txt1 = "
" + (index + 1) +"	<input name=\"sanityItem\" size=\"20\" maxlength=\"255\" type=\"text\">	Not available yet
";               $(txt1).insertAfter(this);             var lastRow = $("#sanityTestsTable tbody > tr:last");                             // This does not work:             lastRow.on("change", null, lastRow, $("input[name='sanityItem']").change() );          }       });    } });   Howver the change event is not caught on new inserted rows. New rows are only added when initial rows 1 or 2 are edited. When you enter text into new row (e.g. 3) then I like further empty rows to appended. What is the proper usage of .on() call? I also tried with .bind() but no success either.  After many "try and errors" I got it:  function changeHandler() {         var emptyRows = 0;         $("#sanityTestsTable tbody > tr td:nth-child(2) input").each(function(){ if ( $(this).val() == "" ) emptyRows++; });                 if ( emptyRows < 2 ) {             $("#sanityTestsTable tbody > tr").each(function(index){                 if ( $(this).is($("#sanityTestsTable tbody > tr:last")) ) {                     var txt1 = "
" + (index + 1) +"	<input name=\"sanityItem\" size=\"20\" maxlength=\"255\" type=\"text\">	Not available yet
";                       $(txt1).insertAfter(this);                     // Attach change handler to last row                     $("#sanityTestsTable tbody > tr:last td:nth-child(2) input").on("change", function() { changeHandler() });                 }             });         }  }  $("input[name='sanityItem']").change( function() {changeHandler()} );


How to get latitude /longitude in Degree Minute Second (DMS) using QGIS field calculator?

I  have come up with the following expression to convert 5.1234   to   5° 7`24.24"   toint ($x) || '° ' || toint((($x) - toint ($x)) * 60) ||'`' || substr( (tostring(((($x) - toint ($x)) * 60) - toint((($x) - toint ($x)) * 60)) * 60),1,5) || '"'  Here’s the problem : for some  points such as 5.1234, it works. but for others,  it doesn’t.  I suspect the problem is the integer conversion which round up the decimal figures instead of truncating it.  Is there any other option? thanks.


Is it possible that a sourced shell script knows its location? I've read  but the answers focus on bash and tcsh and fail if a POSIX shell is used. .  A solution doesn't need to be 100% reliable. It's unlikely that the path contains hard or symlinks.  # sourcing the script should yield the absolute path to the script . somedir/thescript  # within “thescript” -> /tmp/foo/bar/somedir   Some background: The script is part of an existing application containing dozens of binaries in a bin directory in a known location (varies per architecture) relative to the sourced script. To use the application the user sources the script which prepends the bin directory to the PATH, so the application's binaries can be easily invoked in the current shell (whichever shell that might be).


Spinner selection not passing into "if" statement

I have the following code:  public void convert() {      String val = (String) spinner1.getItemAtPosition(spinner1.getSelectedItemPosition());     System.out.println(spinner1.getItemAtPosition(spinner1.getSelectedItemPosition()));     System.out.println(val);     if(val == "mm" || val == "cm" || val == "m" || val == "km")     {         System.out.println("got into if statements");         initiateLengthConvert();     }     System.out.println("never got it");    }   Now when the first to print statements print out, if I selected "mm", then it prints out:  mm mm never got it   Why won't it pass into the if statement? "val" and the possibilities match up, so it doesn't make any sense to me.


How to solve the differential equation for power series $(1+x^2)y'' - 6xy=0$ for $x_{0}=0$

I have tried for the power series but when suppose the solution is $y(x)=\sum _{n=0}^\infty a_nx^n$ appeared sums dependents of $a_n$, $a_{n+2}$ and $a_{n-1}$ and this is not possible.  assume $y(x)=\sum _{n=0}^\infty a_nx^n$ solution,  so   $ y'(x) = \sum_{n=1}^\infty na_nx^{n-1}$ and $y''(x)=\sum_{n=2}^\infty n(n-1)a_nx^{n-2}$  then the equation $(1+x^2)y'' - 6xy=0$ is:  $\sum_{n=2}^\infty n(n-1)a_nx^{n-2}+ \sum_{n=2}^\infty n(n-1)a_nx^{n} - \sum_{n=0}^\infty 6a_nx^{n+1}=0$  We can shift the dummy indices, taking k=n−2 in the first sum, k=n in the second sum and k=n+1 in the last sum:  $\sum_{k=0}^\infty(k+2)(k+1)a_{k+2}x^k+\sum_{k=2}^\infty k(k-1)a_{k}x^k- \sum_{k=1}^\infty6a_{k-1}x^k=0$  taking $k=0$ and $k=1$, we have $2a_{2}=0$ so $a_2=0$ and $ 6a_3x-6a_0x=0$ so $a_3=a_0$. For $k>1$ we have  $(k+2)(k+1)a_{k+2} + k(k-1)a_k - 6a_{k-1}=0$  so  $a_k=\frac{ 6a_{k-1} -(k+2)(k+1)a_{k+2} }{k(k-1)}$    and $a_2=0, a_3=a_0$.  but this recorrence not determines the solution cause $a_k$ depends of $a_{k-1}$ and $a_{k+2}$.


How do I get just the date when using MSSQL GetDate()?

DELETE from Table WHERE Date > GETDATE();   GETDATE() includes time.  Instead of getting  2011-01-26 14:58:21.637   How can I get:  2011-01-26 00:00:00.000


I need to look up for agreements from '2014-06-01' to $today. I am trying to make loop.   $today=date('Y-m-d 00:00:00');  $first_day=$my_counter['Counter']['created'];  $pointer = $first_day;            while ($pointer < $today) :             echo $pointer."<br>";             $pointer = $pointer + '24:00:00';  // +86400 or +1d not work                         endwhile;


Tikz: foreach loop and hard-coded version producing different output

It seems to me that the following two pieces of tikz code should be equivalent; why do they produce different output?  Is there a way I can get the output of the hard-coded variant using a loop?  \documentclass[tikz]{standalone} \usetikzlibrary{calc} \begin{document}  \begin{tikzpicture} \def \m {3} \foreach \s in {1,...,\m} {   \node (tmpnode\s) at ({90 - 360/\m * (\s - 1)}:1cm) {$\s$}; } \foreach \s in {1,...,\m} {   \draw[bend left,->] let \n1={1+int(mod(\s,\m))} in (tmpnode\s) to (tmpnode\n1); } \end{tikzpicture}  \begin{tikzpicture} \def \m {3} \foreach \s in {1,...,\m} {   \node (tmpnode\s) at ({90 - 360/\m * (\s - 1)}:1cm) {$\s$}; } \draw[bend left,->]  (tmpnode1) to (tmpnode2); \draw[bend left,->]  (tmpnode2) to (tmpnode3); \draw[bend left,->]  (tmpnode3) to (tmpnode1); \end{tikzpicture}  \end{document}


C# Call generic method with type as string with lambda argument

Lets say I have: public class ConcreteJob {     public void ExecuteConcreteJob(string someParam) { } }  I am used to execute it on Hangfire scheduler: var client = new BackgroundJobClient(); client.Enqueue<ConcreteJob>(job => job.ExecuteConcreteJob("test_string_param"));  Now I would like to replace concrete type ConcreteJob with its string representation "ConcreteJob". Use reflection and do something like this (very simple said): client.Enqueue<"ConcreteJob">(job => job.ExecuteConcreteJob("test_string_param"));  I am getting lost in all the reflection... Lambda as parameter makes this different from other threads on stack overflow. What I have so far: var jobType = Type.GetType("ConcreteJob"); MethodInfo methodInfo = typeof(BackgroundJobClient).GetMethod("Enqueue").MakeGenericMethod(jobType); var funcDelegateType = typeof(Func<>).MakeGenericType(jobType); dynamic lambda = Expression.Lambda(funcDelegateType,         Expression.Call(             Expression.Parameter(jobType, "job"),             jobType.GetMethod("ExecuteCleanup"),             Expression.Constant(UserPrincipalName))     ); methodInfo.Invoke(client, new[] { (Action)(lambda) });


I've been working on a new method for analyzing and parsing datasets to identify and isolate subgroups of a population without foreknowledge of any subgroup's characteristics.  While the method works well enough with artificial data samples (i.e. datasets created specifically for the purpose of identifying and segregating subsets of the population), I'd like to try testing it with live data.  What I'm looking for is a freely available (i.e. non-confidential, non-proprietary) data source.  Preferably one containing bimodal or multimodal distributions or being obviously comprised of multiple subsets that cannot be easily pulled apart via traditional means.  Where would I go to find such information?


I have a question on Holder space.Is the space $C^2(\mathbb{R}^n)$ embedded in $C^{1,\alpha}(\mathbb{R}^n)$? I think in the bounded domain case, this should be true. But what if in the case where the domain is not bounded? Thanks for any hint!


Is it an open problem about Riemman Hypothesis non-trivial zero?

Let's assume RH was correct, and $1/2+Ki$ is any one of non-trivial zero of $\zeta$, is following problem open?  1) $K$ is irrational number  2) $K$ is transcendental number


How to tell whether a field is required or not in Apex by describe fields

I want to know how I tell whether a field is required or not in an Apex controller.   In my controller I get the record id and then get the object of that record by a describe call, then I get all the fields of that object, but I am not able to tell which field is required and which is not.


Does the estimation process in a regression effect multicollinearity tests

Does the applicability of VIF vary based on the parameter estimation process? For example, can I use VIF to check for multicollinearity if the parameters in my logistic regression are estimated using the Maximum Likelihood method or non-linear least squares for example?  When I look at the VIF formula it appears to me that it should be applicable for any regression, linear or non-linear given that the dependent variable itself isn't in the actual equation. However, surely the parameter estimation process plays a part in whether is multicollinearity or not?


if $f > g$ for all $x$ on $[a,b]$, is the $\int f > \int g$ on $[a,b]$?

I know that there is a theorem saying that if $f \geq g$ on $[a,b]$, then $\int f \geq \int g$, but I am wondering if we only have $f > g$, can we absolutely get a result of $\int f > \int g$.   From the proof, it seems that it is possible that if $f > g$, $\int f = \int g$, but this does not make intuitive sense to me.   Any help would be greatly appreciated.


i have a computer with windows xp home edition. I want to install Ubuntu. I am connect to the internet on a windows 10 computer. I want to create a cd/dvd for the xp computer. how is that done?


Use Digital Persona DLL Library in Linux server

I don't have much experience with Linux OS. I managed to use ctypes in Python to access a function in Digital Persona SDK DLL file using this code: import ctypes dpfjDll = ctypes.CDLL("dpfj.dll") .....  Testing of calling the function worked perfectly on my windows machine, but when I deployed the app to our linux server, I got the following error: OSError: dpfj.dll: cannot open shared object file: No such file or directory  Any idea what is going on? Update: I tried for testing to set the absolute path temporarily for the file, and now I am getting this error message: OSError: /home/......./main/helper/dpfj.dll: invalid ELF header


I'm accessing a directory from my cross-platform c++ code. I know that this directory has three sub directories, but their names are randomly generated.  What I want is a list with the names of these directories (not files!) as type std::string. I would very much like to avoid using libraries, such as boost or qt, and keep to standard c++, if possible.


Let $n\in\mathbb{N}$ and $x_1,x_2,x_3.....,x_n \in\mathbb{Q}$ with $x_i > 0$ and $\prod_{i=1}^{n} x_i = 1$  prove that $\sum_{i=1}^{n}x_i \geq n$ (hint:use induction).  Been stuck on that for hours. It seems as if the terminology of the question is not well defiened because they use "Let $n\in\mathbb{N}$" and not "For each $n\in\mathbb{N}$"   Could I get some insight and help please?


What is the Taylor series for the function $f(x)=\cos(x)$ centered at $a=(-\pi/4$)?

The title is the extent of the problem. It is a problem from my Calculus II practice test that I am having trouble solving.


Is it wrong to say $ \sqrt{x} \times \sqrt{x} =\pm x,\forall x \in \mathbb{R}$?

Is it wrong to say $$ \sqrt{x} \times \sqrt{x} =\sqrt{x^2}= \pm x$$ I am quite sure that  $\sqrt{(x)^2} = \pm(x)$  But, does $\sqrt{x } \times \sqrt{x} =- (x)$ doesn't holds in $\mathbb{R}$ but if we assume $\mathbb{C}$ it holds right?


How to find regression coefficients $\beta$ in ridge regression?

In ridge regression, the objective function to be minimized is: $$\text{RSS}+\lambda \sum\beta_j^2.$$   Can this be optimized using the Lagrange multiplier method? Or is it straight differentiation?


I accidentally deleted the entire "downloaded" album full of pictures from my Samsung Galaxy S2 (SPH-D710) and am trying to use a  I downloaded.  My phone will not show up as a remove-able storage device on my computer, or on the program. I have tried to change the USB settings on my phone but there is no USB settings when I go to Settings > Wireless and networks as most information instructs.   I found the setting for USB debugging by going to Settings > Developer options and can turn that on and off, but that is the only setting I can find relating to USB storage.   When I connect it to the USB cord it gives me MTP or PTP options but again no USB options.   Any advice??? Thank you!


Message for duplicates on Meta sites is incorrect

On Meta sites we can close a question as a duplicate of another question which has no answers.    Which makes the current duplicate message incorrect:       marked as duplicate by USER X hours ago      This question has been asked before and already has an answer. If   those answers do not fully address your question, please ask a new   question.   At the time of writing,  is closed as a dupe of  which has no answers, but the close reason is as above (stating "already has answers").    This is for Meta sites only, main sites are different as you cannot close as duplicate if the supposed dupe question has no answers.


Why Latex cannot compile when I add "\left[ ]\right"

Successful code:  \documentclass[a4paper,cs4size,UTF8]{ctexart}                         \usepackage{amsmath}                  \usepackage{mathtools} \usepackage{amssymb} \begin{document} \end{document} \begin{equation} \begin{split} & L_1=\frac{1}{2} Trace \left[ \sum_{i=1}^{n}\sum_{p=1}^{i} (U_{ip}J_iU_{i1})\dot{q}_p\dot{q}_1 +\dots +     (U_{ip}J_iU_{it})\dot{q}_t \dot{q}_2+\dots +(U_{ip}J_iU_{ii})\dot{q}_p\dot{q}_i)  \right]\\ & \quad =\frac{1}{2} Trace [\sum_{i=1}^{n} \\ &  (U_{i1}J_iU_{i1})\dot{q}_1\dot{q}_1 +\dots +(U_{i1}J_iU_{it})\dot{q}_1  \dot{q}_t+\dots +(U_{i1}J_iU_{ii})\dot{q}_1\dot{q}_i \\ & +(U_{i2}J_iU_{i1})\dot{q}_2\dot{q}_1 +\dots +(U_{ip}J_iU_{it})\dot{q}_2 \dot{q}_t+\dots +(U_{i2}J_iU_{ii})\dot{q}_2\dot{q}_i \\ & + \qquad \vdots \qquad \quad  +\qquad \qquad \vdots \qquad \qquad \quad +\qquad \qquad \vdots \\ & +(U_{ii}J_iU_{i1})\dot{q}_i\dot{q}_1 +\dots +(U_{ii}J_iU_{it})\dot{q}_t \dot{q}_2+\dots +t(U_{ii}J_iU_{ii})\dot{q}_i\dot{q}_i  ] \end{split} \end{equation} \end{document}   However,when I add \left[ ]\right  \documentclass[a4paper,cs4size,UTF8]{ctexart}                         \usepackage{amsmath}                  \usepackage{mathtools} \usepackage{amssymb} \begin{document}  \begin{equation} \begin{split} & L_1=\frac{1}{2} Trace \left[ \sum_{i=1}^{n}\sum_{p=1}^{i} (U_{ip}J_iU_{i1})\dot{q}_p\dot{q}_1 +\dots +     (U_{ip}J_iU_{it})\dot{q}_t \dot{q}_2+\dots +(U_{ip}J_iU_{ii})\dot{q}_p\dot{q}_i)  \right]\\ & \quad =\frac{1}{2} Trace \left[\sum_{i=1}^{n} \\ &  (U_{i1}J_iU_{i1})\dot{q}_1\dot{q}_1 +\dots +(U_{i1}J_iU_{it})\dot{q}_1  \dot{q}_t+\dots +(U_{i1}J_iU_{ii})\dot{q}_1\dot{q}_i \\ & +(U_{i2}J_iU_{i1})\dot{q}_2\dot{q}_1 +\dots +(U_{ip}J_iU_{it})\dot{q}_2 \dot{q}_t+\dots +(U_{i2}J_iU_{ii})\dot{q}_2\dot{q}_i \\ & + \qquad \vdots \qquad \quad  +\qquad \qquad \vdots \qquad \qquad \quad +\qquad \qquad \vdots \\ & +(U_{ii}J_iU_{i1})\dot{q}_i\dot{q}_1 +\dots +(U_{ii}J_iU_{it})\dot{q}_t \dot{q}_2+\dots +t(U_{ii}J_iU_{ii})\dot{q}_i\dot{q}_i  \right] \end{split} \end{equation} \end{document}   It failed,So my question is how to resolve this problem.


In the following example of mine, is it possible to substitute "until" for "by" or not? - You must be home by 7 o’clock. I guess until doesn't work here.


Geometric intuition of the dimension of Grassmannians and flag manfolds

I wish to understand geometrically (not just algebraically) why the dimension of the Grassmanian $G(k,n)$ is $k(n-k)$ and the dimension of a flag manifold $F(k_{1},k_{2},...,k_{n},N)$ is $\sum_{i=1}^{n}k_{i}(k_{i-1}-k_{i})+Nk_{n}$ (in fact with understanding the Grassmanian case it would be enough because the flag are just "nested" Grassmanians).  I am thinking in a spatial way in the well known $G(2,5)$ but I am unable to see geometrically how the space of all $2$-planes in $\mathbb{P}^{5}$ can be $6$-dimensional.


Set bash as default program for *.rdp files

I have a xfreerdp connection file like:  xfreerdp /v:10.1.60.151 -sec-nla /cert-ignore   The file name is test.rdp and I can run it with bash in a terminal with the command bash test.rdp    But I need to run this file from GUI with double click.     I'm tryng to set bash as default to open *.rdp files but I couldn't figure out I can do that.  I don't mind changing the filename extension   I also want to know if I can run this file directly when I download with Chrome.


How to show $c_n=\frac11 + \frac12 + \cdots + \frac1n - \ln n$ is a sequence of positive numbers?

For  $n \in \mathbb{N}$ let  $c_{n}$ be defined by $$c_{n}=\frac{1}{1}  + \frac{1}{2} + \cdots + \frac{1}{n} - \ln n$$     We have to prove that $c_{n}$ is a decreasing sequence of positive numbers. I've already shown the first part, that it is a decreasing sequence by considering the difference of   $$c_{n+1}-c_{n} = \ln \left(1- \frac{1}{n+1} \right) +\frac{1}{n+1} $$ and then using the expansion of $\ln (1-x)$ for $-1\leq x \leq 1$. But I'm having some trouble in showing the second part that all terms in the sequence are positive. I tried using first form of induction but but stuck in the inductive step, can somebody please suggest explain that to me? or better suggest some other way to prove that part? Any sort of welcome as log as it leads to the solution, thanks in advance.


I downloaded all the files that came along the iso of ubuntu 15.10 provided on the ubuntu website. But when i copied them to a usb, it shows no signs of the 15.10 installer. PLSSSS help!!!


Crond stopped sending e-mails for no apparent reason

I have a cron job that I want to run just once a day (executes a rake task), but while I'm testing it I have it set to run every 5 minutes. It was running perfectly fine this morning and sending me e-mails with the output but it has inexplicably stopped sending me mail.   When I checkout /var/log/syslog I can see that the cron job is still running, but the line that normally shows an email being sent has stopped appearing.  When I run service postfix status I get postfix is running.   I haven't changed the cron job itself. I still have this:  MAILTO="myemail@gmail.com" */5 * * * * cd /u/apps/myapp/current && /usr/local/bin/rake my_task RAILS_ENV=staging   No idea what's going on here. Any ideas?


How do I generate random integers within a specific range in Java?

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


How can I get a ClamAV report on infected files in the terminal?

I scanned my system with CLamAV by the terminal and I wanna know what files are infected. How can I get a report for that?  I want a report on my last scan, not on the next one


Why Ubuntu disconnects from wifi when turning on hotspot and how to solve this problem?

Why Ubuntu disconnects from Wi-Fi when turning on hotspot and how to solve this problem??


Anti-Aliasing for Regions in C# and Alpha Masking

I want to draw a torus onto a given picture. The torus/ring itself should be drawn with transparency. Because there is no drawTorus, I use graphics path to get the result.  That's my code so far:  Image bmp = Bitmap.FromFile(Application.StartupPath + "\\background.jpg"); Graphics g = Graphics.FromImage(bmp); g.SmoothingMode = SmoothingMode.AntiAlias;  Rectangle r1 = new Rectangle(bmp.Width / 2 - bmp.Height / 2, 0, bmp.Height, bmp.Height); Rectangle r2 = Rectangle.Inflate(r1, -50, -50);  GraphicsPath p1 = new GraphicsPath(); p1.AddEllipse(r1); GraphicsPath p2 = new GraphicsPath(); p1.AddEllipse(r2);  Region re = new Region(p1); re.Xor(p2);  g.FillRegion(new SolidBrush(Color.FromArgb(80,0,0,0)),re); g.Save();   The result looks like this:   The problem with this is, that SmoothingMode is ignored. You can see it here:   I've read that this is because Regions aren't affected by the SmoothingMode parameter.   But how to fix it?    Is there an other way to write the code above without regions? I read about AlphaMasking over , but this also won't work, because it would influence the transparency of the torus, too.


What is the difference between RS-232 and TTL UART?

I always need to communicate with the TTL UART port on the MCU with a computer. When I talked about that, people always refer the UART port as an RS-232 port. Are they correct? If not, what is the difference between them?  Also, can I use a RS-232-to-USB converter for a TTL UART port?


Have red shifted photons lost energy and where did it go?

I think the title says it. Did expansion of the universe steal the energy somehow?


While reading Reid's "Introduction to Algebraic Geometry", I came across the following passage:     "A finitely generated $k$-algebra is a ring of the form $A = k[a_1,\cdots,a_n]$, so that $A$ is generated as a   ring by $k$ and $a_1, \cdots , a_n$; clearly, every such ring is isomorphic to a quotient of the polynomial ring,   $A = k[X_1, \cdots ,X_n]/I$"   My question is: why must such ring be isomorphic to a ring of the form $k[X_1, \cdots ,X_n]/I$?


Are there canon examples of students permanently transferring from one school to another in Potterverse?

Are there either examples, or a mention of this having happened, of students permanently transferring from one magical school to another in Potterverse?  Canon only please (books/JKR/Pottermore).  Please note that I am only asking about transfers, e.g. you must already be studying in one school. Therefore an example of Malfoys considering sending Draco to Durmstrang is not in scope, since that happened before he attended Hogwarts. Also, guest-studying during Tri-Wizard doesn't count as it wasn't permanent.  Also, if the answer is a "no", please provide evidence (other than "well I read the books before and I don't remember a single case like that", unless you have eidetic memory) from entire canon.


Airplane bathroom:       Why are there ashtrays in the bathrooms on nonsmoking flights?


My iPhone won't download certain free apps

My App Store keeps saying this item is free in the store, that this item will be added to your purchases, and will be available even if your family sharing status changes. And it then says cancel or download.  I click download and it won't download and keeps popping up the same message over and over again. How do I make it stop? I can't download certain free apps.


Passing table-valued parameter for IN operator

How can I pass string parameter with table-value for stored procedure in SQL Server (using c#).  My code:  C#  SqlParameter tvpParam = cmd.Parameters.AddWithValue( "@inoper", "'New York','Boston'");         tvpParam.SqlDbType = SqlDbType.NVarChar;   Stored procedure:  ... WHERE     City IN (@inoper)...   What am I missing here?


Determine the Galois group of $X^4 - 2X^2 +2$ over $\Bbb Q$ and prove $\sqrt 2 \in \Bbb Q(\alpha)$ where $\alpha$ is a root of $X^4 - 2X^2 +2$

Determine the Galois group of $X^4 - 2X^2 +2$ over $\Bbb Q$   EDIT : I want to address the particular polynomial and not the full general case. In order to solve this problem, I want to have a self-contained proof/answer and am not willing to reproduce the general argument when even it might not be required. If you can provide help overcoming this simple obstacle then please help, instead of just lazily labeling the question as duplicate !  The result that is being linked\suggested, it boils down to the same problem whether $\sqrt 2$ is in the field $\Bbb Q(\alpha)$ or not, so it's pointless to refer the link just by merely looking at the form of the polynomial!  Mt attempt :  Obtained roots of $X^4 - 2X^2 +2$ to be : $\pm \frac{1}{\sqrt 2}(\sqrt{1+\sqrt 2} \pm i \sqrt{\sqrt 2 -1})$ . Then considered $\Bbb Q(\alpha)$ where $\alpha=\frac{1}{\sqrt 2}(\sqrt{1+\sqrt 2} + i \sqrt{\sqrt 2 -1})$ .  So I need to show whether $\frac{1}{\sqrt 2}(\sqrt{1+\sqrt 2} - i \sqrt{\sqrt 2 -1}) \in \Bbb Q(\alpha)$  or not (then the Galois group will be of order 4 or 8 respectively) .   I have observed that $\sqrt 2 \in \Bbb Q(\alpha) \implies $ $\frac{1}{\sqrt 2}(\sqrt{1+\sqrt 2} - i \sqrt{\sqrt 2 -1}) \in \Bbb Q(\alpha)$  So, (1) How to show (if it is true) $\sqrt 2 \in \Bbb Q(\alpha)$ ?  (2) How to obtain the Galois group ? If (1) is true I was tempting to use computational tricks like the ones exhibited in    Thanks in Advance for help!   has been asked on this polynomial before, but the OP was confused himself , I could not follow his arguments and most importantly the question did not had any answer.


Are there fields and ordered fields of every infinite cardinality?

On the top of my head, I cannot think of any fields of cardinality more than that of the reals. (It is known that the process of algebraic closure does not increase the cardinality of an infinite field.)  What is the simplest way to give an example of a field (and an ordered field) of a specific cardinality $\alpha$?  I see there is the "Field" of surreal numbers, but it is a proper class rather than a set (and hence do not have a cardinality as such). However, there seems to be some modified construction which gives proper fields with the cardinality of some strongly inaccessible cardinal.


Why does my .bash_history contain duplicate segments?

Since I keep my bash history under source control, I've noticed that sometimes sizable segments of the history end up repeated, sometimes hours or days after their original execution. I use Debian 7.7 and have the following config:  shopt -s histappend  export HISTCONTROL=ignoreboth:erasedups export HISTSIZE=1000000 export HISTFILESIZE=1000000   I suspect there is some interaction between multiple terminals, histappend, and erasedups. I'm answering this question myself but if someone disagrees or has more detail I would like other answers!  Edit: I believe this is not a duplicate -- there are many questions asking how to ignore duplicate entries; I'm asking about getting rid of a buggy behavior around mistakenly duplicated history segments. (Whole chunks repeated that I had actually executed only once.)


Difference between $\mathbb{Z}/p\mathbb{Z}$ and $\mathbb{Z}_p$

Assuming $p$ is a prime obviously, am I missing something or are both sets just $\{0, 1, \dots, p-1\}$. I also still don't fully understand what a quotient is, so maybe that has something to do with this? Please enlighten me.


I just installed Virtualbox, and the latest (Ubuntu 14.04 LTS), and the only USB device which detects is my Logitech mouse.  I'm using VirtualBox.


Google doesn't use meta description on SERP

We changed the sites UI, CMS, link structure. Also Bought a new and better domain name. After we completed everything. We did below step by step;   Created a new web application for old.com/page1.html to new.com/page1.html 301 redirection. Used webmmaster tools for 301 redirection. Sent new sitemaps a long with robots.txt   Although we've got a custom title,meta descrpition and meta keywords for every page, Google takes a piece of sentece from content and uses it for MetaDescription. This is a big problem for our potential clicks on SERP. What should we do for getting back MetaDescription?  The old site is : indirimkodlari.gen.tr  The new site : indirimkodu.gen.tr  Google still shows the old url and right meta description with it.    The new domain name with randomly scraped on Google search of site.com/url    Solution Looking at Google's search cache by using "view source" shows we used the wrong field from database for MetaDescription! Changed it, fixed, and solved!.


Hard Drive Full With Files From Removed App,, How Do I Delete Space So I Can Boot?

I recently used deluge to download a torrent but forgot to set the location as a USB drive so my hard drive had 0bytes remaining, I deleted the file and used force quit to kill deluge as it was hanging. Unfortunately I pressed the mouse too soon and killed unity which caused the system to crash. Now I can't boot, I get a "couldn't get size" error on a black screen. In recovery the hard drive is showing as "103gb - 98% used, 0% free". I don't think I removed the file from deluge and normally if you delete a file from a hard drive but don't delete it from your torrent client, the free space does not show up, it only shows up when you remove it from the torrent client. So I figured this could be the problem. I removed deluge from root shell prompt, hoping it would free up the missing 5gb but it didn't. I've used clean and fcsk but I can't free up any more space, I did free up 167mb of space by removing un-needed packages but I still don't have any free space. I tried running Nautilus to remove any remaining files from deluge, but it won't run, can't remember what the exact error was but it couldn't run a display server or something, I guess cos of the lack of space ? I've been trying to fix this for days, can anyone help ? Thanks


I do want to order CTP by year. I have a taxonomy called 'annee' (year), and a CTP called 'moto' (motorbike). Issue is, when im trying to order by the taxonomy, it's ordering only by taxonomy ID, and not by Taxonomy Value. Do you have any solution ?   if ( is_post_type_archive( 'motos' ) ) {      $query->set( 'posts_per_archive_page', 24 );     $query->set( 'order', 'DESC' );     $query->set( 'orderby', 'meta_value_num' );     $query->set( 'meta_key', 'annee' );     return; }      Thank you.


java - Null pointer exception when calling a method

For reasons that even my com sci teacher can't figure out, I am trying to call a method in my main but when i run the program, java throws the following error:  Exception in thread "main" java.lang.NullPointerException         at GUIcreatorr.AddComponents(GUImaker5.java:390)         at GUImaker5.main(GUImaker5.java:425) Java Result: 1 BUILD SUCCESSFUL (total time: 5 seconds)  here's my code:  `class GUIcreatorr implements ActionListener {     private JFrame frame;     private CardLayout cardLayout = new CardLayout();     private JPanel contentPanel;      //more constructors here for the various panels i am adding to contentPanel      public void AddComponents()     {         //ADDS ALL FIVE PANELS TO CONTENT PANE         contentPanel.setLayout(cardLayout);         contentPanel.add(panelMenu,"panelMenu");         contentPanel.add(panelMenu,"infoPanel");         contentPanel.add(panel1,"panel1");         contentPanel.add(panel2,"panel2");         contentPanel.add(panel3,"panel3");         contentPanel.add(panel3,"winPanel");         contentPanel.add(panel3,"losePanel");          frame = new JFrame("Maple Gang-Gang: Shooting Cups game");         frame.setContentPane(contentPanel);         cardLayout.show(contentPanel, "panelMenu");          frame.setSize(1000, 800);          frame.setLocationRelativeTo(null);          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);          frame.setVisible(true);      }      @Override         public void actionPerformed(ActionEvent e)         {         throw new UnsupportedOperationException("Not supported yet.");         } }  public class GUImaker5 {     public static void main(String[] args)     {         GUIcreatorr letsPlay = new GUIcreatorr();          letsPlay.AddComponents();      }  }`   As you can see, my method AddComponents takes all the panels i created in previous methods of the same class, and adds them to a content pane to be displayed. Am I doing something wrong, or is there a way to simply make java ignore the NullPointerException error? I am a beginner programmer, but I've heard of using try/catch exceptions. should I use one of those to fix my problem,and if so how?  thanks in advance for the desperately needed help!!!


I need the data within 2 Parentheses.   Something sorta like this.  textBox1.Text += "IndexError[0] : (untabbedIndex) in Program.cs";   I need to only get the untabbedIndex in the string. I've tried splitting the string again, but no luck.


I have downloaded an osm file from Geofabrik download server and opened this .osm.pbf-file in QGIS. So there are 5 classes - lines, multiline strings, multipolygons, other_relations, and points.  I wanted to add some additional number of points and give them attributes in this vector layer. And finally, save it as .osm.pbf again, As I need the .osm.pbf for osmosis.  Is there a method to do the same? As editing in that layer is not happening.


Are there any divisibility rules using 7?

Divisibility rules of 1,2,3,4,5,6,8,9 are first or second grade math. Are there any divisibility rules for numbers with factors including 7. I noticed that the digits of 7x starting with x=1 to x=5 have digits that add up to 7, 5, 3, 10, and 8.


Where does Google Chrome for Linux store user specific data?

Where does Google Chrome for Linux store user specific data such as bookmarks ?  I can't find a .chrome or .google directory under my home directory, any other directory I should look at ?


$\int e^{\cos(x)} \cos(nx)\ dx$ using the residue theorem

I am trying to evaluate the following integral using the residue theorem:  $$\int_0^{2\pi} e^{ \cos(\theta)} \cos(n\theta) d\theta$$  I have already evaluated $\int_0^{2\pi} e^{e^{-i\theta}} e^{i n\theta} d\theta$ using the residue theorem by making the substitution $z = e^{i\theta}$ and then finding the coefficient of the $z^{-1}$ term in the Laurent series expansion. Now, however, this no longer works, so any help would be appreciated.  Thank you.


floating point errors / how to truncate two decimal places in python

I am trying to truncate (by two decimal places) an array of floats in a numpy array. I do this by doing the following to each element: np.trunc(100 * i) / 100  However, due to some floating point problems in python, sometimes this formula above does not work. Take for example -2.01 * 100 = -200.99999999999997. Thus, the np.trunc(100 * -2.01) / 100 will not work. it will output -2.00. Is there a better way to truncate two decimal places in python using np.trunc? Without np.trunc? Thank you!


Deriving torque equation from Newton's 2nd Law

I'm trying to understand the derivation of the torque equation $\vec{r} \times \vec{F} = I \alpha$. My textbook derives this easily enough from Newton's 2nd Law for a single point with mass $m$ and  radial distance $r$, with the force applied at the same distance $r$, as (if we drop the vector notation for simplicity) $F=ma=m(r\alpha)$, so $rF=mr^2 \alpha = I\alpha$. (Note, there are both 'ay's and 'alpha's there; they look similar.)  The textbook stops there and concludes that the equation holds for any rotating body. But then I tried this derivation for two points positioned along a rigid, massless rod (which points perpendicular to an axis about which it rotates). If there's a point-mass $m_1$ a distance $r_1$ from the axis of rotation and another point-mass $m_2$ at a distance $r_2$, and the force is applied at (for example) distance $r_2$, I get $F=m_1 a_1 + m_2 a_2 = m_1 r_1 \alpha + m_2 r_2 \alpha$, so  $r_2 F= (m_1 r_1 r_2 + m_2 {r_2}^2 )\alpha$. But $m_1 r_1 r_2 + m_2 {r_2}^2$ isn't the correct value for $I$ here. What am I missing?


Please undo tag merge of [cordova] and [phonegap]

There has been a  about this and the accepted and high voted answer was not to merge. Still the merge was done [status-completed].  A     about this issue because this merge is simple wrong.  It is like merging Chrome into Webkit.  Yes, there has been confusion about the two names when Cordova was new but this .  So please stop this merge.


BigDecimal.Divide gives incorrect result

I am getting incorrect result while performing the division using BigDecimal. number1 = 221500.0 number2 = 12.0 Here is my code snippet:  BigDecimal d1 = new BigDecimal(String.valueOf(number1)).setScale(13, 4); BigDecimal d2 = new BigDecimal(String.valueOf(number2)).setScale(13, 4); return (d1.divide(d2, 13, 4 )).doubleValue();   18458.333333333332  if I performed the same calculation using the calculator it gives  18458.333333333333333333333333333  Let me know any issues with handling the scale in BigDecimal. It will be helpful if someone let me know how to arrive the same result with calculator.


Some Sold State Disks (SSD) have a  (MTBF) of 2,500,000 hours. If you divide that by the rough number of hours in a year you get 2500000÷(365×24) ~= 285 years before there is a problem.  I know that the first generation SSD's used to have a short life - but now the estimated time before they fail seems absurdly high. Most warranties only cover them for 1-3 years it seems.  How long are the modern, SATA III drives supposed to last?


How is the kurtosis of a distribution related to the geometry of the density function?

The kurtosis is to measure the peakedness and flatness of a distribution. The density function of the distribution, if it exists, can be viewed as a curve, and has geometric features (such as curvature, convexity, ...) related  to its shape.  So I wonder whether the kurtosis of a distribution is related to some geometric features of the density function, which can explain the geometric meaning of kurtosis?


Which way to draw diode in a circuit diagram

Im having a bit of trouble drawing a circuit with a diode in. I know the current flows from negative to positive, but convention says that current goes from positive to negative.  When drawing a circuit with a diode do you draw the arrow pointing to the positive (matching the actual flow of electrons) or towards the negative terminal (matching conventional current)?  If you follow convention then surely when building circuits from the diagram the diode will not allow current as it is actually facing the incorrect way?


where should I ask a question about using Microsoft Word?

I've got a problem using Microsoft Word - surely there's a Stack Exchange site for that, isn't there?


What is wrong with my reasoning on this ACT English question

I am taking the ACT english section, and I came across this question. The background is "Even in the middle of winter, the sun, high in a blue sky, keeps me warm. Like me, wildlife avoids the ski resorts; I spot tracks made by elk, coyote, fox and even the endangered lynx".  The question is asking about the word in bold, "me". It is asking which pronoun I should replace it with, or if I should keep it. The options are:  A: No Change B: them, C: we, D: I,  I initially said D, I, as the answer. I did this because I rearranged the sentence so it read "Wildlife avoids the ski resorts like I do". The answer is A, not D. What am I doing wrong in this question? Any help would be appreciated.


I need help in solving this proof when $p_1$, $p_2, \dotsc, p_n$ are distinct prime numbers

So I was working on one of the exercise question for school and I came across this question and I wanted to know if someone can help me in providing a proof for this question. So the question is:  Prove if $p_1, p_2,\dots , p_n$ are distinct prime numbers where $p_1 = 2$ and $n > 1$ then $p_1p_2p_3 \dots p_n + 1$ can be written in the form $4k + 3$ for some $k \in \mathbb N$.


How do we perform transverse measurements in a two level system?

In quantum mechanics any two level system can be mapped onto effective spin variables. If the system is defined by two energy levels, $|E_1\rangle$ and $|E_2\rangle$, the Hamiltonian is  $$ H = \left(\begin{array}{cc} E_1 & 0 \\ 0 & E_2 \end{array}\right) \, .$$  This can be recast as  $$ H = \frac{E_1+E_2}{2} 1\!\!1 + \frac{E_1-E_2}{2} \sigma_3\, .$$  $1\!\!1$ is the identity operator and $\sigma_3$ is the third pauli matrix. This is very nice because we can now apply our knowledge and intuition of spin dynamics to any two level system.  My question is the following: for a real spin I can measure expectation values of $\sigma_{1,2}$ by physically rotating my system and align its $x$ or $y$ axis with my measuring apparatus. How do I do this (in the lab!) with a pseudo-spin system? Imagine I am looking at a cold atom and I want to know if the system is in an symmetric or anti-symmetric superposition of $|E_1\rangle$ and $|E_2\rangle$, how do I do it?


I followed some instructions to uninstall Ubuntu on my HDD because I would like to reinstall Ubuntu on an external HDD.   I burned the image on a dvd. Unfortunately when starting the computer with the DVD, Windows was was completely uninstalled (I was trying to uninstall Ubuntu).  Therefore is it possible to go back and restore windows?


How to prove $\int_{-\infty}^{+\infty} f(x)dx = \int_{-\infty}^{+\infty} f\left(x - \frac{1}{x}\right)dx?$

If $f(x)$ is a continuous function on $(-\infty, +\infty)$ and $\int_{-\infty}^{+\infty} f(x) \, dx$ exists. How can I prove that $$\int_{-\infty}^{+\infty} f(x) \, dx = \int_{-\infty}^{+\infty} f\left( x - \frac{1}{x} \right) \, dx\text{ ?}$$


Traveling to Edinburgh then up to the Highlands then to Ie of Skye and finally to Glasgow. Any tips on what to pack for clothing?


Is there any parameter (in terms of physical quantities such as mass, length, charge...) which can be used to decide when to treat a system quantum mechanically and not classically?


Any application wherein i can create photo mosaic

I am new to Ubuntu and  I wonder if there's an application that i can install so  I can create mosaic out of my photos.  Any help is much appreciated.


Sum of 3 correlated normal random variables

I know that sum of 2 correlated normal random variables are written as $X+Y\sim N(\mu_x+\mu_y,\sigma^2_x+\sigma^2_y+2\rho_{xy}\sigma_x\sigma_y)$, I am now wondering how is 3 correlated normal random variables are constructed. Is it in the form of $X+Y+Z\sim N(\mu_x+\mu_y+\mu_z, \sigma^2_x+\sigma^2_y+\sigma^2_z+2\rho_{xy}\sigma_x\sigma_y+2\rho_{yz}\sigma_y\sigma_z+2\rho_{xz}\sigma_x\sigma_z)$? Thank you so much!


Determining confidence interval with one observation (for Poisson distribution)

When you make only one measurement, how do you determine 95% confidence interval for the Poisson distribution?  Let's say that I make one measurement of a quantity $x$ and obtain $x=10$. Also it is known that the population $x$ is Poisson-distributed. If I want to calculate 95% confidence interval for the population mean, then how can I find the corresponding z-score?   One says the margin of error for 95% is $1.96\lambda$. I wonder how to obtain the $1.96$. Please note that in the example above the sample size is one.


Cant upload SVG files after updating Wordpress 4.7.1

I updated Wordpress to 4.7.1 and cant upload SVG anymore.  I had a function in my functions.php file   function cc_mime_types($mimes) {    $mimes['svg'] = 'image/svg+xml';    return $mimes; } add_filter('upload_mimes', 'cc_mime_types');   but it also dont help now.


UV Filter that best suits Nikon 18-140 mm lens

Please let me know the size of UV filter that best suits Nikon 18-140 mm lens.


In blender 2.81a, there are two denoising tools:   Under layer properties, you can scroll down and enable denoising Also in layer properties, you can check "denoising data" under passes > data and in the compositing workspace, you can add a denoising filter        Is there a difference between these two? If so, what is different and is one of them "better" (faster, more efficient etc) than the other?  Any help would be appreciated. Thanks


how to handle figure when using subfiles in latex document

when I am using subfiles in my tex document: \subfile{./chapter-2020-02/chapter-2020-02}  when the subfile using figure like this: \begin{figure}[htbp]     \centering     \includegraphics[scale=0.3]{mavenauthpassword}     \caption{Maven}     \label{fig:mavenauthpassword} \end{figure}  shows this error: ! LaTeX Error: File `mavenauthpassword.tex' not found.  what should I do to using figure correctly when using subfiles in latex document?


in Internet Explorer 8, view source with Notepad

How can I set Internet Explorer 8 the old style "view source" to open with Notepad?  (I set HTML editing to Notepad, but I want the Right-Click - View source to open in notepad)


C++ singleton - when is the destructor called?

The following seems to be the recommended way to define a singleton in C++:  class Singleton { private:      Singleton();  public:     static Singleton & get_instance() {         static Singleton instance;         return instance;     }       ~Singleton() {         // destructor      }      Singleton(Singleton const&) = delete;     void operator=(Singleton const&) = delete; }   Now, take this function:  void foo() {    Singleton & s = Singleton::get_instance(); }   I expected the destructor to be called when the singleton instance goes out of scope in that function, but it's not. When does the destructor get called?


"Is there any notebook on the desk?"  "There isn't any notebook on the desk."   I read these sentences in a worksheet made by someone whose native language isn't English.   Are these sentences grammatically correct?   Because I thought any is used with aren't and are  "Are there any notebooks on the desk?"  "There aren't any notebooks on the desk."


How to check if my code is subjecte to sql injection

How to check if my code is subject to sql injection . I am new to php,I followed the code from w3schools php tutorial,But i think this code is subject to sql injection.Please help me by telling how can i avoid sql injection in the following script.Any help will be appreciated   $conn = =mysqli_connect("localhost","root","123456","db");     $conn->set_charset("utf8");     // Check connection     if ($conn->connect_error) {       die("Connection failed: " . $conn->connect_error);     }     $i=0;     for($i=0;$i<count($_SESSION['storecart']);$i++){     $sql = "INSERT INTO cart( fname, email, mobile, commaddress, city, zipcode,state, country, vazhipaduuser, mainlist, price, date, nakshatram) VALUES ('".$_SESSION['user']['fname']."','".$_SESSION['user']['email']."','".$_SESSION['user']['mobile']."','".$_SESSION['user']['commaddress']."','".$_SESSION['user']['city']."','".$_SESSION['user']['zipcode']."','".$_SESSION['user']['state']."','".$_SESSION['user']['country']."','".$_SESSION['storecart'][$i]['name']."','".$_SESSION['storecart'][$i]['mainlistdata']."',".$_SESSION['storecart'][$i]['price'].",'".date('Y-m-d', strtotime($_SESSION['storecart'][$i]['date']))."','".$_SESSION['storecart'][$i]['nakshatram']."');";     //echo $sql;          if ($conn->query($sql) === TRUE) {      // echo "New record created successfully";     } else {       //echo "Error: " . $sql . "<br>" . $conn->error;     }     }     $conn->close();


Let $u:\mathbb{C}\rightarrow\mathbb{R}$ be a harmonic function such that $0\leq f(z)$ for all $ z \in \mathbb{C}$. Prove that $u$ is constant.

Let $u:\mathbb{C}\rightarrow\mathbb{R}$ be a harmonic function such that $0\leq u(z)$ for all $ z \in \mathbb{C}$. Prove that $u$ is constant.  I think i should use Liouville's theorem, but how can i do that? Help!


What is the difference between the command  $ env FOO=bar baz   and  $ FOO=bar baz   What effect does env have?


How to add Ubuntu image to Windows 8 boot menu

Is it possible to add an image to the Windows 8 boot menu for Linux/Ubuntu?


I have a problem with shortcuts after upgrading to Ubuntu 17.10, and have no idea how to debug it.   Problem is following: When I use shortcuts like Shift+Alt+Insert it behaves as Shift+Insert or Alt+Insert depending on which key was pressed first.   It's possible that is's only java problem (I have this behavior stably reproducible in CLion IDE, and unstable in others), but seems it's overall problem.   Is is some known issue, or is there any easy way to debug which presses/released events are happen?  UPD: Seams, I got the problem. Alt+Shift is set up as keyboard layout change shortcut. So, when shift is pressed, alt press changes layout and not delivered to applications, and visa versa if alt is already pressed, shift is not delivered. Is there any way to fix it?


working with the refreshApex feature in LWC

Okay, i'm looking to see if I can get some help in understanding the documentation as laid out here:   I want to refresh a component after a record CRUD operation, the form is being populated from a call to an apex method. The data from this method (called with the @wire service) is then passed into a js function that splits the data into complete and incomplete todo items. Wire service call is:     @wire(getTodos, {     searchKey: '$searchString'   })   sendForSplitting({     error,     data   }) {     if (error) {       this.error = error;     } else if (data) {       this.splitTodos(data);     }   }   In an event handler i want to trigger an update to this dataset, the documentation above seems to reference that I can refresh the apex on a wired method. From that doc:      To refresh a wired method, you must pass the argument the wired method receives (which is the wired value).   To date, I have tried both:     handleCreate() {     return refreshApex(getTodos, {       searchKey: '$searchString'     });   }   and    handleCreate() {     return refreshApex(this.sendForSplitting({       error,       data     }));   }   Both of which throw errors - refresh failed because configuration is not available. How can I make this work? I want to ensure the lists update upon user interaction without having to resort to a manual refresh of the page...


Draw Cone intersected by a plane in Latex

how do I draw this using Tikz package in latex?


Variable coefficient rises, then falls as lambda decreases (LASSO)

I am regressing a continuous predictor on over 60 variables (both continuous and categorical) using LASSO (glmnet).  In examining the variable trace plot, I notice that as log lambda increases, one of the key variables has a coefficient that actually increases.  Then, after a certain point, it begins to decrease like we would expect.    To make sure this wasn't a fluke, I ran 10 models using bootstraps and obtained very similar results.    Is this possible, or is there a problem with the data?  If legitimate, what does this trend in the variable's coefficient tell us about the variable and the relation to the response?


What tense should this sentence be phrased in based on the accompanying action which has taken place?

In the following scenario you can buy/sell offices in different cities, so say the user purchases an office in London, then the user sells it and we wish to show the user a message that the sale has taken place, should it be phrased like:  this,     You sold your Office which is situated in London for  495,000.   or     You sold your Office which was situated in London for  495,000.


Native Youtube app suddenly stopped working on iPad 1

It's been some weeks now, whenever I try to used my Youtube app, it tells me it's impossible to connect to Youtube. Since it's an iPad 1, I have had trouble finding information online.  Did Google or Apple stop supporting the app? Is it finally obsolete? Is there another app I could use that works on iOS 5?  Just to be clear, I did not tinker with my device. I did not change its parameters, I did not jailbreak it, it connects to the Internet just fine and I've tried the app on different Internet connections. Also, this is not a login problem, the app just refuses to let me browse videos, whether I'm logged in or not.  Thanks for your help.


Use (Windows) BitLocker-encrypted drive on Ubuntu 14.04 LTS

How could I mount my BitLocker encrypted drive on Ubuntu?  I have checked the  website, and it had no BitLocker support, and I have no idea how to install Dislocker on my computer.   I can not remove the encryption because my school computers use Windows OS instead of Linux OS. Also because I installed Ubuntu because my Windows OS was not working.


Does anybody know if exists a solution for this bug?

I have been using ubuntu 13.10 (amd64bits) for a while and always the same problem happen with me when I add a new VPN connection.  My problem is the same as described in the follow website ->    The process name with bug is : nm-connection-editor. I also try to kill the process but without success.  Obs.: Between first problem (+-7months ago) and today, I had updated my OS a few times, the bug still alive! One important thing about kill the process, if I do not kill, the process still using around 30% of my CPU, but if I kill the process, then it turn to 0% CPU usage, but still showing as a process alive. ;(  Any idea how to get around??


How do you set up a python project to be able to send to others without them having to manually copy and paste the code into an editor

I made a cool little project for my friend, basically a timer using tkinter, but I am confused on how to let them access this project without having vscode or pycharm. Is it possible for them to just see the Tkinter window or something like that?  Is there an application for this? Sorry if this is a stupid question.


WiFi driver for Qualcomm Atheros rev[30]

My wifi is working fine on Windows 10 but it is not detecting in Linux.  I am facing the same problem as described in   How can I fix this?


Getting base name of the source file at compile time

I'm using GCC; __FILE__ returns the current source file's entire path and name: /path/to/file.cpp. Is there a way to get just the file's name file.cpp (without its path) at compile time? Is it possible to do this in a portable way? Can template meta programming be applied to strings?  I am using this in an error logging macro. I really do not want my source's full path making its way into the executable.


Left-aligning LaTeX Bibliography Display

I have problem on how to make the bibliography item left-aligned. My current bibliography output is below.    As  you can see, the reference item code is currently right-aligned, and I need it to be left-aligned. Any idea on how to achieve that?  My current code for the bibliography is  \usepackage{natbib} %.... \nocite{*} \bibliographystyle{alpha} \bibliography{references}   Thank you.  update  Below is the code after i reduce many of it. The problem still occur on this code. I use MiKTeX 2.9.  \documentclass[bahasa, 12pt, a4paper, final]{report} \usepackage{babel} \usepackage{natbib} \usepackage{url}   \begin{document}     \nocite{*}     \bibliographystyle{alpha}     \bibliography{references} \end{document}


Be somewhere "on time", "at that time" or "in time"?

Do both imply the same meaning?   John told me to be there at 6pm. I will be there on time. John told me to be there at 6pm. I will be there in time. John told me to be there at 6pm. I will be there at that time.   I can feel that in time needs a for or a to but am not sure. Like in I'll be there in time for the show to start. or  I'll be there in time to see it. (on time won't work)


Finite Groups as Galois Groups of Field Extensions

Let $F$ be a field, and $x_{1}, \dots, x_{n}$ free variables. Let $K=F(x_{1},x_{2},\dots,x_{n})$, being the fraction field of the ring of polynomials in the variables $x_{1},\dots,x_{n}$. Show that $S_{n} \subset \mathrm{Aut}(K)$, and in particular, use this result to show  that any finite group $G$ is the Galois group of an extension of fields.    I'm lost on how to show this. I've seen other answers around, but they invoke the Fundamental Theorem of Galois Theory (which I haven't seen). What would be a way to get started on this problem? (and if possible without using the Fundamental Theorem of Galois Theory). I know that for the second statement, one would need to use Cayley's Theorem at some point.    Thanks for the help!


What is the difference between zooming in and cropping?

If I take a photo by zooming in (optical) and cropping a photo without zoom. What would be the difference between the two?  I know cropping reduces the photo quality but I'm interested in other differences, if any.


Is there any reason why i wouldnt be asked to update to new 16.04?

I could just do it via usb but why the hassle if you don't have too, any reason why it wouldn't just be offering the update?


In Javascript  parseInt(null) returns a NaN parseNumber(null) also returns a NaN    isNaN('abcd') returns true, as 'abcd' is of course not a number, isNaN(5) returns false    but strangely    isNaN(null) returns false, which is odd as implies it is a number, but as we saw in the parseNumber it was seen by that as NaN  There appears to be an inconsistency between the way null is viewed by parseInt and by isNaN one sees it as NaN and the other sees it as a Number. Why are they inconsistent?