Which armor/weapon type is the strongest to forge?

I like to relay on my own forged armor and custom enchants it giving it a more personal touch since i spent all that cash/time buying/collecting the items needed to make the armor  I got Deadric and Dragonbone smithing perks and looking at the initial stats of the armors Deadric has a greater value despite that Dragonbone needed a Blacksmithing skill of 100 to unlock the perk.  My Flawless Platemail has been beating initial Orcish armor for a while so knowing that i can further improve Dragonbone and Deadric Armor, with a Blacksmithing skill of 100, no potions to boost and being able to improve armor/weapons right after i forge them, i am wondering which armor/weapon set is more powerful to forge, Deadric and Dragonbone  NOTE 1: i use a one-handed sword (ie. Blades katana) so for comparison between Deadric and Dragonbone sets only compare one-handed swords, not maces or axes   NOTE 2: the enchantments on my armor don't boost resistances to attacks (they mainly boost Mana regeneration and Carry Weight) and my sword always has a 1 second Soul Trap so answers should avoid possible increases to attack/armor rating done via enchantments  NOTE 3: an answer doesn't need to be all Deadric/Dragonbone or even include them (as i am just going by the last 2 perks in the Blackmithing Skill), it just need to include Armour i can make in any forge and further improve at the armor bench/grind stone


Flashlight switch: display the desired state or the current state

Situation: I need to design a view in a mobile application (iOS + android) to scan qr-codes. The view needs a toggle to switch the flashlight "on" and "off". Problem: I first designed the switch that represented the current state of the flashlight (V1). This means that when the flashlight is "off" the icon shows a crossed out light bulb and when the flashlight is "on" the icon shows a glowing light bulb.  Like toggles work in settings for example:  When I tested my design in a prototype (Adobe XD) is feels very strange to turn on the flashlight by clicking on an icon that shows a crossed out light bulb. For this reason I have created another variant that shows exactly the opposite:  When I want to turn "on" the light, I click on the icon with the light "on " When I want to turn "off" the light, I click on the icon with the light "off".  It's like a play and pause button on a music player  When I want to play the song, I click on the play icon When I want to pause the song, I click on the pause icon     I had a discussion with a colleague about whether it makes sense to display what the user wants to achieve, or the current state. Displaying the current state makes less sense to me in this context, because the user knows that the flashlight is off when sitting in the dark. And as I said it feels weird to click on this crossed out icon. Now I am successfully confused how to solve this problem. I think it's not good to break the switch behavior everyone is used to know, even if it feels weird to me. What do you guys think?


Flask, one flash message not getting displayed

I know flash is set up properly as all other flash messages are being displayed correctly.  I have updated one view. It used to call the flask route from a javascript window.location function but now am using $.post() to send parameters to the route.   The location of the flash call hasn't changed (I put a print statement just before it and that executes so I know the interpreter gets to the flash call).   All code in the route's method executes correctly but the flash message does not show and I am at a loss. Nothing coming up from Google searches.  Here are the last 3 lines in the route method  db.session.commit() flash('Database Updated') return redirect(url_for('index'))


Extension of a morphism $k^*\rightarrow X$ to $\mathbb{P}^1\rightarrow \overline{X}$

EDITED: In the context of defining the Hilbert-Mumford criterion for stability in moduli problems, we need to extend the morphism of varieties $\lambda_x:k^*\rightarrow X$, (where $X$ is a quasi projective variety and $k^*$ is seen as an algebraic group) to a morphism defined in $\mathbb{P}^1$.  We identify $a\in k^*$ with $[1:a]\in\mathbb{P}^1$. So we want to extend the morphism to $[0:1]$ and $[1:0]$. It seems that the extension always exist in this context. The answers I'm finding involucrate schemes and the valuation criterion for properness.  Is there simpler answer in the context of varieties?  Thank you so much.


Error in sudo apt update in ubuntu 20.04

sudo apt update Err:17 http://ppa.launchpad.net/leaeasy/dde/ubuntu focal Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]      Err:18 http://ppa.launchpad.net/mc3man/trusty-media/ubuntu focal Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]       Err:19 http://ppa.launchpad.net/mc3man/xerus-media/ubuntu focal Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]      Err:20 http://ppa.launchpad.net/petrakis/wdt-main/ubuntu focal Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]      Err:21 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]      Err:22 http://ppa.launchpad.net/webupd8team/java/ubuntu focal Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]      Err:23 http://ppa.launchpad.net/webupd8team/java/ubuntu eoan Release        404  Not Found [IP: 2001:67c:1560:8008::15 80]      Reading package lists... Done      E: The repository 'http://ppa.launchpad.net/leaeasy/dde/ubuntu focal Release' does not have a Release file.      E: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu focal Release' does not have a Release file.      E: The repository 'http://ppa.launchpad.net/mc3man/xerus-media/ubuntu focal Release' does not have a Release file.      E: The repository 'http://ppa.launchpad.net/petrakis/wdt-main/ubuntu focal Release' does not hav      E: The repository 'http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu focal Release' does not have a Release file.      E: The repository 'http://ppa.launchpad.net/webupd8team/java/ubuntu focal Release' does not have       E: The repository 'http://ppa.launchpad.net/webupd8team/java/ubuntu eoan Release' does not have   I upgraded Ubuntu version to 20.04. Now I can't use "sudo apt update" or "sudo apt-get update". It gave me those PPA errors. Can anyone help me to fix those errors. Thank you.**


Wald test in regression (OLS and GLMs): t- vs. z-distribution

I understand that the Wald test for regression coefficients is based on the following property  that holds asymptotically (e.g. Wasserman (2006): , pages 153, 214-215): $$ \frac{(\hat{\beta}-\beta_{0})}{\widehat{\operatorname{se}}(\hat{\beta})}\sim \mathcal{N}(0,1) $$ Where $\hat{\beta}$ denotes the estimated regression coefficient, $\widehat{\operatorname{se}}(\hat{\beta})$ denotes the standard error of the regression coefficient and $\beta_{0}$ is the value of interest ($\beta_{0}$ is usually 0 to test whether the coefficient is significantly different from 0). So the size $\alpha$ Wald test is: reject $H_{0}$ when $|W|> z_{\alpha/2}$ where $$ W=\frac{\hat{\beta}}{\widehat{\operatorname{se}}(\hat{\beta})}. $$  But when you perform a linear regression with lm in R, a $t$-value instead of a $z$-value is used to test if the regression coefficients differ significantly from 0 (with summary.lm). Moreover, the output of glm in R sometimes gives $z$- and sometimes $t$-values as test statistics. Apparently, $z$-values are used when the dispersion parameter is assumed to be known and $t$-values are used when the dispersion parameter is esimated (see ).  Could someone explain, why a $t$-distribution is sometimes used for a Wald test even though the ratio of the coefficient and its standard error is assumed to be distributed as standard normal?  Edit after the question was answered   also provides useful information to the question.


Is there an elementary proof that $n \mid \phi(p^n-1)$?

When I teach finite fields, one fun corollary is that $n \mid \phi(p^n-1)$, where $\phi$ is the Euler-phi function and $p$ is prime.  I spent several minutes in my office after class one day looking for an obvious reason.  But I failed.  I couldn't see a proof that doesn't essentially recast the argument that the cyclotomic polynomial $\Phi_{p^n-1}(x)$ splits into all primitive polynomials of degree $n$ in $\mathbb{Z}_p[x]$.  Is there an elementary (let's say "polynomial-free") proof of this divisibility?  More generally: Prove that for all positive integers $a,n$ with $a > 1, n | \phi(a^{n}-1)$.


How do you split a string into tokens in C++?


Saving Processing result to GeoJSON string instead of QgsVectorLayer or GeoJSON file

I run processing.run("native:buffer") and from newly created vector I get all features and export them to string using QgsJsonExporter(). My problem is that newly created vector gives new IDs to all features and they aren't equal to attribute ID's values. And after exporting them to GeoJSON using QgsJsonExporter() I get GeoJSON features with identifiers. However I can solve this by declaring processing.run("native:buffer") algorithm OUTPUT to .geosjon file and opening it afterwards. Is there a way that I can get GeoJSON string without IDs without having to save OUTPUT to .geojson and reading it to string afterwards. vl = QgsVectorLayer(sys.argv[1],"mygeojson","ogr")  def runProcessingNativeBuffer(inputGeoJson, distance):     processing.algorithmHelp("native:buffer")     return processing.run("native:buffer",                          {'INPUT': inputGeoJson,                           'DISTANCE': distance, 'SEGMENTS': 5,                           'END_CAP_STYLE': 0, 'JOIN_STYLE': 0,                           'MITER_LIMIT': 2, 'DISSOLVE': False,                           'OUTPUT': "TEMPORARY_OUTPUT"})  ats = runProcessingNativeBuffer(vl, sys.argv[2])  vl1=ats['OUTPUT']  features = vl1.getFeatures() exporter = QgsJsonExporter() print("GEOJSON",exporter.exportFeatures(features))  IDs in properties are fine I don't need additional IDs in "features"


Splitting string into pair of characters in Ruby

I have a string (e.g. "AABBCCDDEEFF") and want to split this into an array with each element containing two characters - ["AA", "BB", "CC", "DD", "EE", "FF"].


It is well known that a two dimensional system to first order is locally Hamiltonian from Darboux' theorem. For example,  \begin{equation} \dot x = f(x,y), \qquad \dot y = g (x,y)  \end{equation} Admits the following Poisson structure,  \begin{equation} \{x,x\}=\{y,y\} =0 , \qquad \{x, y\}= -\{y,x\} = F(x,y)  \end{equation} Where $F\neq 0$ and Hamilton's equations being,  \begin{equation} \dot x = F(x,y) \frac {\partial H}{\partial y}, \qquad \dot y =-F(x,y) \frac{\partial H}{\partial x} \end{equation} If now we have an $n$-dimensional system $\dot x_i=f(x_1,\dots , x_n)$ where $i=1,\dots , n$, can we in general give conditions for the admission of a Hamiltonian system?   If I had a system and wanted to solve it's dynamics, is there a way I could test to see if it is Hamiltonian? By this I mean, let us assume I have a collection of variables and can monitor their time evolution in a computational experiment. Is there a way I can use the very powerful theory of Hamiltonian mechanics to someway solve my own system? i.e how can I take it beyond the use of $q$s and $p$s to solve my own problems!


Note: I didn't downvote! (yet)  Earlier today, I flagged an answer as it really wasn't an answer at the time. However, the poster later added a JSFiddle example (which didn't really answer the question either but merely repeated the OP's post) but it got a few comments going, and got the OP engaged, which resulted in some useful comments before the answerer bowed out. The OP also commented via their own comments and on other posts.  It is the habit of this particular user, s/he should have used the comments IMHO to extract the extra info needed or make their original observation in the first place, and I shouldn't have been so quick off the mark with a flag! I'm not worried about the wrong flag but what if anything should or can be done in a situation similar to this.  I know it was likely a "FGITW" type answer, where a user was hoping to edit (may still happen) but again IMO it failed this time. If it was me who'd tried it, I would delete but then I wouldn't want to delete what may be useful comments = hence the quandary and my question.  Is there anything that can be done to either retract the flag or explain why the flag in the first place (beyond the original not an answer!)?  My apologies to whoever saw my flag!


I have just downloaded a google-font. I want to use it in a specific section of the page. I think I am using the font in an incorrect manner.  .page-header {     font-family: 'Calligraffitti', cursive;     src : url('../fonts/Calligraffitti/Calligraffitti-Regular.ttf'); }   If this is incorrect, could you tell me the correct way of using a font that is not installed on a system?


How to prove that $(X^y - X) \bmod 3 = 0$ always when $y$ is odd and $y > 1$, and $X >1$?


Why is type I error not affected by different sample size - hypothesis testing?

I don't understand why the probability of getting a type I error when performing a hypothesis test, isn't affected. Increasing $n$ $\Rightarrow$ decreases standard deviation $\Rightarrow$ make the normal distribution spike more at the true $µ$, and the area for the critical boundary should be decreased, but why isn't that the case?  (Cross posted on .)


How do I disable "Link Preview" in Chrome?

This feature magnifies links when it seems unsure of which you touched. .  Beyond its annoyance, as I have to click everything twice, this bubble seems to break several dropdowns, as the menus will not expand in the zoomed view because the zoomed view is just a glorified image.


I have a hard time verbalizing how shocked and horrified I am to learn that questions can be and actually are deleted.  The only reasonable use case I see is spam or very clear abuse.  But anything else should not be put to death. At the age of 6, in my first school year, I learned: "Every question has value." "There are no bad questions."  I still consider this true to this day.  Deleting questions is so senseless. Why delete information? What seems unimportant to you might be important to someone else! You can't objectively measure that.   That's what we have the voting system for. Popular questions rise to the top automatically. Very unpopular ones drop to the bottom.  I have been a passionate contributor until now, but if I know that my questions can be deleted anytime, (as well as my answers to deleted questions) I don't see any point in contributing my work. If I spend my time and it gets deleted, my work was completely in vain. There are few things I despise more in this world than senselessness. And creating something that is destroyed is the the ultimate senselessness.  I would recommend treating all work respectfully. Preserve information. This is like burning books. Please stop that, this is horrible. Thank you.  Questions are being deleted . Or for .


Strange fringe pattern on long exposure photo

While compositing a series of long exposure images, I noticed this strange fringe-like pattern getting brighter at each layer blended in "lighten" mode. It features a circle and a cross in the middle and those deformed lines around it, sightly brighter than the rest of the image. It looks like a lens issue, but I've shot some sky photos with it before, , so I think a badly placed light source could be the cause of this effect.  Lens: Vivitar 28-210mm F3.5-5.6 AF Zoom  Camera: Canon t5i  Shot at 28mm F3.5, 20 images of 30s each, raw, no camera denoise.  Is there a way to remove such pattern? Is it something common in this kind of setup?


I have started to use TexStudio for making my documents in LaTeX (beginner mode, by the way); and I was wondering if there is any software that allows to make graphs so they can be transformed directly to LaTeX. I mean not necessary plots, but like a sort of Paint so that I can export the graphs to LaTeX, if they are TexStudio plugins would be great.


How can I evaluate $\sum_{n=2}^\infty n(n-1)x^n$?

How can I evaluate $\displaystyle\sum_{n=2}^\infty n(n-1)x^n$?   I know the answer thanks to Wolfram Alpha, but I'm more concerned with how I can derive that answer.


Singular or plural verb for compound subject?

Which is correct?  "When quality and integrity matter..." or "When quality and integrity matters..."?


Is it possible to use whose as the possessive form of which?    Based on classic films -- whose screenplays were mostly dramatic -- Bordwell exposed his theory of the hero.    Is that correct?


Must you have an uncompleted destination card in Ticket to Ride?

Put another way, once you complete the destinations on your initial destination cards, do you have to draw a new destination card or can you play without having an uncompleted destination?


Disable cache for specific sites in Chrome

Is there a way to tell Chrome to disable caching for specific sites? I'm doing dev work, and I'd like to avoid caching localhost.


Is the following statement is True/false ? reagarding closed ball

Is  the following statement is True/false ?  For $x∈\mathbb{R}^n$ , let $B(x,r)$ denote the closed ball in $\mathbb{R}^n$(with Euclidean norm) of radius $r$ centered at $x$. Write $B=B(0,1)$.If $f,g:B→\mathbb{R}^n$ are continuous functions such that $f(x)≠g(x)$ for all $ x∈ B$, then   There exist $ϵ>0$ such that $ B(f(x), ϵ) ∩ B(g(x), ϵ)=\varnothing$  for all $ x∈ B$  My attempt :  i take  $f(x) = x$, $g(x) = x+1$, now  i visualize the diagram  i take $ϵ$ as constant  that greater then $0$  from  the diagram  i can conclude that this statement is false .  Is  its  True ?  any hints/solution will be appreciated  thanks u


If $A+A^T$ is negative definite, then the eigenvalues of $A$ have negative real parts?

Assume that $A$ is non-symmetric. "If $A+A^T$ is positive definite, the eigenvalues of $A$ have positive real parts" (originally, it was with negative definite/negative real parts, but I suspect it doesn't matter). This was claimed in a comment of an answer to .   Could anyone provide a proof for this?  Is the other direction true? If yes can anyone present a proof, if not a counterexample.  If $A$ is diagonalizable is the other direction true? If yes can anyone present a proof, if not a counterexample.    Thank you.  (In case anyone wonders what the motivation behind this is, I'm looking into it with the hope of getting some simple geometric intuition for the conditions of asymptotic stability of the origin of a continuous-time LTI system $\dot{x}=Ax$ (i.e. that the eigenvalues have negative real parts). If the other direction of the claim is true, it implies that the angle between the velocity vector $\dot{x}$ and the position vector $x$ is always greater than $\pi/2$, hence the state is always 'being pushed roughly in the direction of the origin'.)


Proving that an integer is even if and only if it is not odd

There is , but the definition of "even" and "odd" that I am using uses integers instead of just natural numbers; i.e.,   An integer $n$ is even iff there is some integer $k$ such that $n=2k$. An integer $n$ is odd iff there is some integer $k$ such that $n=2k+1$.   Here is what I have so far:  First we show that an integer $n$ is even or odd. We first use induction on the positive integers. For the base case, $1=2\cdot0+1$ so we are done. Now suppose inductively that $n$ is even or odd. If $n$ is even, then $n=2k$ for some $k$ so that $n+1=2k+1$ (odd). If $n$ is odd, then $n=2k+1$ for some $k$ so that $n+1=2(k+1)$ (even). This closes the induction, so every $n\in\mathbf{Z}^+$ is even or odd.  Now we show every $n\in\mathbf{Z}^-$ is even or odd. Let $n\in\mathbf{Z}^-$. Then $n=-k$ for some $k\in\mathbf{Z}$ (I think this follows immediately from most definitions of the integers.). Suppose $k$ is even. Then $k=2j$ for some $j$ so that $n=-k=-2j=2(-j)$ (even). Now suppose $k$ is odd. Then $k=2j+1$ for some $j$ so that $n=-k=-(2j+1)=-2j-1=-2j-1+1-1=-2j-2+1=2(-j-1)+1$ (odd).  For $0$, note that $0=2\cdot0$ (even).  Now we show that $n\in\mathbf{Z}$ cannot be both even and odd. Suppose for the sake of contradiction that $n\in\mathbf{Z}$ is both even and odd. Then there are integers $k,j$ such that $n=2k=2j+1$. This implies that $2(k-j)=1$ (like in the referenced question). So we must show that $1$ cannot be even in order to complete the proof.  This is where I am having trouble. I know that if I let $f:\mathbf{Z}\to\mathbf{Z};x\mapsto2x$ be a function, then $f$ is increasing so since $f(0)=0$ and $f(1)=2$ and $0<1<2$, there is no integer $m$ such that $f(m)=1$. But this seems complicated so I was wondering if there was an easier way to do this.  So my real question is: how can I show that $1$ is not even?  (This is not homework.)


Is there an automatic function in QGIS to package all files in a project for transferability?

In my project, I use a lot of geodata from different directories. Now I want to give the QGIS project to a colleague (eg on a CD).  Is it possible to copy the shapes from different directories automatically to one directory?


I need help with the following question:  Find all the integer solutions for: $3x^2+18x+95\equiv 0\pmod {143}$  My solution: First I know that $143=11\cdot 13$ then because $\gcd (11,13) = 1$ then $3x^2+18x+95\equiv 0\pmod {143}$ if, and only if $$3x^2+18x+95\equiv 3x^2+7x+7\equiv 0\pmod {11} \\ 3x^2+18x+95 \equiv 3x^2+5x+4\equiv 0\pmod {13}$$ I don't know how to solve those equations and I don't know how to combine it to the big solution for the real question (I know about the CRT, but I didn't realy understood how to use it, I'd love help with this). thanks in advance


Ubuntu 16.04 freezing when streaming videos

I am having a problem in pinpointing this issue, but here is the info:  Every once in a while, after some time, when I am watching streaming videos (Youtube, Udemy, Teachable, etc.) my laptop would freeze (as in it freezes and the audio keeps repeating the last 1 second). This also happened once when I had spotify open, but I think it was youtube, since I wasn't playing anything on spotify( that has been installed as snap, btw).  When this freeze happens, no matter how much time I wait, try to go for another TTY, nothing works, and I have to "Hard Reset" the machine.  I checked dmesg after reboot, see if I can find anything that helps, but didn't find anything (I am not sure what I am looking for).  I looked around to see if this would be a Firefox problem (latest version from ubuntu's repository), but couldn't find any similar problem.  For the record, this is my system info:  System: Ubuntu 16.04 x64 LTS with Gnome Shell v3.18.5 CPU: Intel(R) Celeron(R) CPU  N2820  @ 2.13GHz RAM: 4GB DDR3 Kernel: 4.4.0-119-generic   The laptop is not overheating, and this doesn't happen when I am listening to music/playing local videos, so I guess it is related to Firefox/wireless card.  Any help in pinpointing this issue will be appreciated. Also, if there's need of any additional info, please let me know.  P.S.: I know there will be the new ubuntu version (18.04) soon, but I really want to know why this is happening, so I don't make the same mistake.


Is there an intuitive explanation why a circle is not contractible?

We can prove that circle is not contractible (homotopic equivalent to a point). But is there an intuitive explanation of why this is so?


Why do radioactive isotopes have a half-life? I know that they decay in order to become stable but why would it take out enough subatomic particles to be half? Or am I approaching this question the wrong way: the remaining radioactive substance is going to be half in x amount of time and the other half will be stable atoms.


How do I start a Cron job 1 min after @reboot?

I need my script to be executed a minute after each reboot. When I apply @reboot in my crontab it is too early for my script - I want the script to be executed after all other tasks that are routinely run on reboot. How might I run the script sometime after reboot?


HP Laser Jet 2035 printer problems with 18.04

I have just upgraded to Ubuntu 18.04. It's all fine, except that my printer, a HP Laser Jet 2035, does not work. I keep getting messages about drivers, but I either can't find them or can't download them?   The printer was working great in 16.04, so I am not sure what advantage I now have!


I understood that LinkedList is implemented as a double linked list. Its performance on add and remove is better than Arraylist, but worse on get and set methods.  Does that mean I should choose LinkedList over Arraylist for inserting?  I wrote a small test and found ArrayList is faster in inserting. Then how does linked list faster than ArrayList?  Please refer the below example which I have done.        import java.util.Date;     import java.util.LinkedList;     import java.util.List;      public class TestLinkedList {          public static void main(String[] args) {              long lStartTime = new Date().getTime();             System.out.println("lStartTime:: " + lStartTime);             List<Integer> integerList = new LinkedList<Integer>();             for (int i = 0; i < 10000000; i++) {                 integerList.add(i);             }              long lEndTime = new Date().getTime();             System.out.println("lEndTime:: " + lEndTime);              long difference = lEndTime - lStartTime;              System.out.println("Elapsed milliseconds: " + difference);          }      }


Imagine the following scenario:  I am using SQL Server 2005. I have a transaction that is calling, among other SQL statements, a stored procedure that also has a transaction inside. The outer transaction sometimes fails and it is rolled back after the stored procedure is called and committed successfully.  My question is, does the stored procedure's transaction rollback too?


I recently came across this definition: Let $(X,d)$ be a metric space and $A$ be a nonempty subset of $X$. For each $x\in X$ we define a distance from $x$ to $A$ by the equation  $d(x,A)=\inf\{d(x,a) | a\in A\}$  I would guess that such a function will be continuous. But is there an easy and rigorous way to prove it?


After installing Debian 8, I started poking around /bin (as I'm always wont to do), and I noticed that ls and vdir share, not only the same manpage (except for the whatis line), but the exact same compiled size. The only thing they don't have in common is the inode number (which seems inefficient, but that's tangential).  Is there any reason for this? What's the historical precedent? Why would we want to have both?  I'd never ever heard of vdir before today, so it can't be immensely common, and it seems like it should be easy to simply have vdir be a script that calls ls with the correct arguments.


Cayley's Theorem and proving $S_n$ is isomorphic to a group of permutations.

If $G$ is a finite group, then $G$ is isomorphic to some subgroup of $S_n$.  I was able to prove this theorem by using the fist part of Cayley's theorem.   But I can't prove that $S_n$ is isomorphic to a group of permutations. How can I show that?


Is there any other word I can use instead of respectively?   This word provides me a way to describe a list of items conveniently in a single sentence and hence save space. I've used this many times and there are mainly two reasons I am asking this:   I'm just looking for alternatives, since I don't want to use the same word everywhere. Another small reason is that I find the word respectively a bit long which makes writing short sentences using it difficult.   Since an example of its use was requested: "Samantha, John and Jack bought apples, mangoes and oranges respectively from the market." (I know it's not a very creative one.)  I also looked for synonyms at  but the only close ones I found were correspondingly and individually. I'm unsure whether these are valid substitutions for the use of respectively as in my example.


HISTTIMEFORMAT modification. In /etc/bash.rc or /etc/profile?

I'd like to add the date/time to the output of the history command in CentOS/RHEL 6. I would like this to apply to all users on the machine by default. This itself is easy. It seems to just be a case of adding:  export HISTTIMEFORMAT="%Y%m%d %T  "   Where should that be added? I've seen some conflicting info on whether to add this to /etc/profile or /etc/bashrc. I believe both would work equally well.  Does anyone have any advice as to which file I should use for this specific modification?


How to recursively find big files in a directory on a Windows 7 operating system

IT is on my case. They say I am using too much hard drive space, and need to use less.  I start looking for the culprits which are huge and are the cause.  Problem is I have multiple nested directories, and am having a hard time finding them.  How can I do find the big files in a given directory and its sub-directories?  Ideally, I would be able to sort them from large to small.  Thanks


For continuous $f$, $\int_0^x f(t)dt = ∫_x^1f(t)dt$ implies $f=0$.

If $f:[0,1]\to\mathbb R$ is continuous and $\int_0^x f(t)dt = ∫_x^1f(t)dt$ then prove that $f(x)=0$.  I suppose that $f(x)$ isn't zero, set $g(x)= \int_y^xf(t)dt$ with $y\in[0,1]$ and use Bolzano but I don't know if it's right.


MySQL Replication : 1 Slave / Multiple Masters

I have a web app with 2 web servers and 2 database servers. The DBs are setup for multimaster replication. (this is the primary environment)  I also have the exact same setup on a different location acting as standby, in case the primary env fails. (this is the backup env)  What I need is for the backup env to be in sync with the dbs of the primary site. However, all DBs in both environments have already replication configured.  How can I achieve my goal?  Thanks


i can not boot to usb drive windows vista

I cannot boot to my USB hard drive with ubuntu as I do not see an option. I have rearranged the boot menu and it still hasn't worked I am using a gigabyte motherboard and at the top of my bios it says 1984-2008 I have been stuck on this for 2 days now


How to install Oxford Advanced Learner's Dictionary 9th on ubuntu 16.04

I have a oxford dictionary mdf file.I want to install in ubuntu 16.4. How to install OALD9 on ubuntu 16.04.


How to sort a list whose elements are dict objects?

I was trying to sort a list whose element is dictionary. I want to sort my list by the key Route. Here I did: MenuList = [     {         'Title': [             {'Description': 'Form Customer Center'},             {'Route': 'LoanCentre'},             { 'Menu': [                 {'Parent': 'Customer'},                 {'Order': 4}             ]}         ]     },     {         'Title': [             {'Description': 'Customer'},             {'Route': 'CustomerCenter'},             { 'Menu': [                 {'Parent': 'Customer'},                 {'Order': 3}             ]}         ]     } ]      print (MenuList.sort())  TypeError: '<' not supported between instances of 'dict' and 'dict'>  Any thought to sort this kind of list please? I just want to get result of this: MenuList = [      {         'Title': [             {'Description': 'Customer'},             {'Route': 'CustomerCenter'},             { 'Menu': [                 {'Parent': 'Customer'},                 {'Order': 3}             ]}         ]     },     {          'Title': [             {'Description': 'Form Customer Center'},             {'Route': 'LoanCentre'},             { 'Menu': [                 {'Parent': 'Customer'},                 {'Order': 4}             ]}         ]     } ]


I have a romex cable feeding an outdoor yard light.  It was cut, I spliced it, soldered it and wrapped it with tape. Is there a way to splice and bury it safely to code?   If not, I'll need to dig a 30 foot trench to replace the whole length.


I have 2 lists:   name = ["Stirling","Lana","Cyril","Pam","Ray","Cheryl"]  alias =["Duchess","Truckasaurus","Chet","Cookie Monster","Gilles de Rais","Cherlene"]   I need to create a dictionary such that the name is the key and alias is the value, in this particular way:  Stirling : Duchess   Also I have to use the for loop to do so.


Program crashes when I try to add contents of a class to on array

I am trying to add a class to an array and I get Exception in thread "main" java.lang.NullPointerException in my addAstronaut class. package gov.nasa.spacevehicles;  import gov.nasa.personnel.Astronaut;  public class SpaceStation {  //private members    private String name;    private double stationWeight;    private double altitude;  private Object[] Astronauts; private int totalAstronauts;  //overloaded constructor public SpaceStation(String name, double weight) {    int altitude = 0;    int totalAstronauts = 0;  }  //method public void addAstronaut(String name, double height, double weight) {      Astronauts[0] = new Astronaut(); // Exception in thread      Astronauts[1] = new Astronaut();      Astronauts[2] = new Astronaut();            stationWeight = stationWeight + weight;    }


Personal checks containing entire account number

I noticed that when I login to my bank account online I have to type my password twice in order to see my full checking account number. Then I was writing a check and noticed the entire account number is at the bottom for anyone to see. That seemed like a security issue to me. Am I being too paranoid or would it be wise to avoid using personal checks because of the account number being visible to anyone? Also, is it possible to request personal checks with the account number partially hidden?


How many combinations are there to pull at least 1 ace with 10 cards.

We have deck of cards (52 cards). 10 random cards will be picked. How many chances are there, that atleast 1 of the random cards is "ace".  At first I tried to calculate how many different possibilities are there to pull 10 random cards without any extra conditions. According to formula nCk= n! / k!(n-k)!: I got 52! / 10! * 42!  Next I tried to calculate how many possibilities are to pull 10 cards from deck, that does not contain any "aces" I got 48! / 10! * 38!  Then I could subtract second answer from first and I would be left over with answer. Since the numbers are too huge to try on calculator, I wondered if my solutions works.


Intersections of all subgroups is a nontrivial subgroup, so every element has finite order.

I need help to prove this result:  "Let $G$ be a group such that the intersection of all its subgroups other than $\{1\}$ is a subgroup different from $\{1\}$. Then all its elements have a finite order".  I know I must think of an element $g$ of infinite order. That will imply that every subgroup has infinite order (because it will contain an element like $g^k$). After this, I don't know which step I can take. Can someone help?


What does the first character of UNIX mode string indicate?

I'm very familiar with linux file permissions, and special perms (sticky bit, suid, guid) But I don't know what the c stands for? Is it a permission, or something else? I've done some googling with and can't figure it out. Here's the device file that has it. steven@A215:~$ ls -l /dev/null crw-rw-rw- 1 root root 1, 3 Dec 29 20:58 /dev/null   Image Reference:


Can a wizard telepathically speak with & control their familiar whilst incapacitated yet conscious?

A wizard (with a familiar) is possessed by a ghost. Can this incapacitated yet conscious-observing wizard still speak telepathically to their familiar, one that is within 100'?


"An SQL Server database schema" or "a SQL Server database schema"?

Possible Duplicate:          I got the following sentence from the book I'm reading:     You can take a database-first approach   by first creating a SQL Server   database schema.   From what I learned, I think it should be "an SQL Server database schema", not "a SQL Server database schema". So which one is correct?


On all the sites I have an account I have the blue avatar, the same as here. But I just noticed that I have a red avatar on Area51. I read  why. Is there a way to get the same avatar on Area51 as I have on Meta? I'd prefer doing this without making Gravatar.


Using boolean subtract to create window holes

To create window holes I used the boolean modifier. It works well 90% of the time, but every now and then it creates these lines in the surface of the solid, visible even though I turn off the wireframe view mode. I tried dissolve Edge, but in edit mode those oblique lines are not seen if I select the boolean solid to subtract.


How to submit form to an other page using jQuery, Ajax with out leaving my page

I want to submit a multipart/form-data form without leaving my page or reloading using jQuery and AJAX. When I submit it with PHP only it does the job well but leaves the page.  HTML:  <form  action="" id="myform" method="POST" class="myform" enctype="multipart/form-data"> <input type="file" id="image" name="file"> <input  border="4" type="submit" value="submit"  id="sumit" name="submit"  class="button" />   jQuery:  $(function() {    $('.myform').submit( function() {         $.ajax({              url    : 'c_create.php',             type    : 'POST',             data    : formdata(),                    success : function( data ) {                          alert('ok');                              },             error   : function(){                          alert('error');                       }          });          return false;     }); });   Any help will be greatly appreciated. Thanks in advance. :)


Almost every solid state physics textbook says crystal momentum is not really physical momentum. For example, phonons always carry crystal momentum but they do not cause a translation of the sample at all.   However, I learned that in indirect-band-gap semiconductors, we need phonons to provide the crystal momentum transfer to make happen electron transitions between the top of the valance band and the bottom of the conduction band. Along with absorbing or emitting photons, of course.   Photons do carry physical momentum. For the purpose of momentum conservation, it seems that phonons do carry physical momentum as well.  How can we explain this?  ========================================  To put it more specifically, I drew a graph to tell the story:    K (capital) is crystal momentum.  For such transition, photon provides most of the energy transfer (and a little momentum transfer hk, k in lower case), phonon provides most of the momentum transfer (and a little energy).  Similar graphs can be found in most solid state physics textbooks. The picture tells me, either the photon participating in the transition carries crystal momentum, which value is equal to physical moemntum hk, or the crystal momentum itself is a kind of physical momentum.  However, one can prove that a phonon does not carry physical momentum (here I quote Kittel's "Introduction to Solid State Physics"):    So, how do we explain the momentum transfer in the electron transition aforementioned?


Setting up From Addresses and SAP in Marketing Cloud

Working on setting up private subdomains through end client. Marketing Cloud has a SAP sku provisioned but where do you obtain the SPF and DKIM to pass to client for DNS setup and how does one access/view the SAP information for the Marketing Cloud instance?


Most fonts broken in firefox after update to 57 (ubuntu 16.04)

After updating to Firefox "quantum" all text on most webpages is gone or show as small squares.    The issue occurs on most websites including google, askubuntu.com and the built in firefox new tab page. It does not occur on mozilla.org or a few other sites I've randomly tested.  Starting Firefox from terminal yields this error message:   (/usr/lib/firefox/firefox:3897): Pango-WARNING **: failed to create cairo scaled font, expect ugly output. the offending font is 'Ubuntu 11' (/usr/lib/firefox/firefox:3897): Pango-WARNING **: font_face status is: file not found (/usr/lib/firefox/firefox:3897): Pango-WARNING **: scaled_font status is: file not found (/usr/lib/firefox/firefox:3897): Pango-WARNING **: shaping failure, expect ugly output. shape-engine='PangoFcShapeEngine', font='Ubuntu 11', text='●'   EDIT:  This appears to be caused by the combination of having fonts stored in a non-default location (on a separate drive from my OS) and  bug in firefox 57.


Script to avoid typing very long password into SSH

I first use my team's account to ssh a server and then login to my server. To login to initial team's account, I need to enter a long very complex 30 character machine generated password and then in the next prompt I enter a pin and yubikey. I cannot use public, private key pair to make ssh easy. Currently I copy that long 30 character password to clipboard and then paste into terminal. Server keeps kicking out inactive connections and I end up doing this many many times. Is there any easy way to accomplish this task? I am open to using any clipboard trips or write a script to do this.


how to add data to an object in js (react)

I am trying that a variable that I have just defined has the value of an object and that I can also add more information to it at the same "level" Something like that:   let obj1 = {   name: "jhon",     address: {       city: "abc123",       country: "def456",       zipcode: "123456",     },     job: {       position: "qwe123",       experience: "12 years",     }, }  let obj2 = {   info1: "abc123456",   info2: "12345678978",   info3: "1234567d78778", }  let myobj = {    name: "jhon",   address: {     city: "abc123",     country: "def456",     zipcode: "123456",   },   job: {     position: "qwe123",     experience: "12 years",   },      info1: "abc123456",   info2: "12345678978",   info3: "1234567d78778",    }  console.log(obj1) console.log(obj2) console.log(myobj)    Let me explain, I want "myobj" to be equal to obj1 and obj2. obj1 and obj2 come from different parts and I want the data to be in "myobj" at the same level, as shown in the code


Trouble centering text over image in flexbox

I have some trouble to centre text over an image in flexbox. I am trying to make 3 images that are next to each other and in the middle of each image there is some text which also has a semitransparent background. I've created a short  to demonstrate my problem.  .hello li {     margin: 24px 0px;     display: flex; }  .hello img {     height: 180px;     width: 300px;     justify-content: space-between; }  .hello li p {     text-transform: uppercase;     background: rgba(36, 36, 36, 0.5);     color: white;     width: 180px;     height: 60px;     position: absolute;     left: 50%;     top: 50%;     transform: translate(-50%, -50%);     justify-content: center;     align-items: center;     text-align: center;     display: inline-flex; }


Stack Overflow - Home - Interesting tab: Showing almost no yellow card (interesting) questions

I am a web developer who is used to navigating the Interesting tab in the Home page of Stack Overflow to find fresh new questions that use the tags that I configured in my profile (JS, HTML, CSS, ReactJS, regex, etc...).  Usually, this tab shows an abundance of yellow card questions, so questions that have at least one of the tags that I am intersted in. However, today, I am seeing almost no such cards and the questions I get in the page have random tags, and even some of them are really old (but with fresh answers).    This behavior seems odd to me and it's disrupting. I am not sure if it's a bug or something the Stack Overflow developers are experimenting with.  Does anybody have a clue what's happening?


Is conservation of momentum and energy valid for non-inertial frames?

Conservation laws of momentum and energy are said to be the most basic principles of physics. Are they also valid for non-inertial frames, and in what way?


Can a smartphone send directly a message to another smartphone 20 miles away?

According to ,      a typical cellphone has enough power to reach a cell tower up to 45   miles away   So, can a smartphone send directly a message to another smartphone 20 miles away?


Multiple types of parts with multiple types of information (unspecified amount)

I'm having trouble designing a database for a project I was working on recently. It's to do with a garage management system.  So I've realised I need to store multiple types of parts (Tyres, engines, wheel bases, this list needs to grow), with multiple types of details, some that each part shares (name, part number, condition, quantity) and some that are unique to each part (engines have weight and power, tyres have size and alloy type) and that also needs to grow too. This can't be limited to just 2 kinds of unique information, it needs to be infinite, so that more can be added at a later date if required  How can I design a database that is capable of storing all of this information without having tables for each specific part, so a table for tyres, a table for engines etc? I want to keep it so the least amount of tables as possible is used, so once designed, no new tables are added as new data is added.  Any help is appreciated.


Induction proof concerning a sum of binomial coefficients: $\sum_{j=m}^n\binom{j}{m}=\binom{n+1}{m+1}$

I'm looking for a proof of this identity but where j=m not j=0    $$\sum_{j=m}^n\binom{j}{m}=\binom{n+1}{m+1}$$


How to copy remote NAS file behind a router

BACKGROUND  A UNIX NAS operates behind a Unix Router.  The router's SSH port is open to the WAN, however the SSH port of the NAS is LAN accessible only.  One is able to SSH to the router from any WAN connections (i.e. Starbucks) from Unix command line (Bash).  To access the NAS, one must provide login through the router and then login to the NAS.  QUESTION  Is it possible to remotely retrieve (from NAS side of router) files from the NAS via:    command-line (scp, rsync, etc)? application (FileZilla)?   Examples are preferred & appreciated.


I play a teleportation and extra dimensional sorcerer in my group and I'm getting close to obtaining the spell  which requires "a diamond worth at least 5,000 gp". How big would a  be? My reason for asking is that I want to place the diamond on top of my legendary staff, and the size definitely dictates whether I can or can not do so.


In my Dell notebook I had installed Windows 10. When I installed Ubuntu 17.04, I can't run Windows from Ubuntu grub/that violet window/. It shows that I have Windows 10 in last row, but when I choose Win10 it doesn't run, only shows grub after dark screen. When I installed Ubuntu I chose the first option: Install with windows 10. How can I solve this problem?


Highlight all keys that look like '&name=' in a text with grep console

I am using grep console plugin in my development environment and I want to highlight parts of my console that look like '&name='.  I tried with following regex: [&].*[=]  I want lines like this:     lorem&variable=something{ipsum}&paramter="555"   to look like this     lorem&variable=something{ipsum}&paramter="555"   What would be the grep command to do that


How can I reduce Spacing of the following subequations:  $ \begin{subequations} \begin{equation} x_{n+1}= x_n + v_n \Delta t + \frac{1}{2} a_n \Delta t^2 \end{equation}     \begin{equation}  v\left(t_n+\Delta t/2\right)= v_n + \frac{1}{2}a_n \Delta t \end{equation} \begin{equation} a_{n+1}=\frac{1}{m} F(x_{x+1},t_{n+1}) \end{equation} \begin{equation} v_{n+1}=v(t_n+\Delta t/2) + \frac{1}{2}a_{n+1}\Delta t \end{equation} \end{subequations} $   I do not know how to embed the code here correctly.


Solve the following equation: $\sqrt {\sin x - \sqrt {\cos x + \sin x} } = \cos x$

Solve the following equation:  \begin{array}{l}{\sqrt{\sin x-\sqrt{\cos x+\sin x}}=\cos x} \\ \text{my try as follows:}\\{\sin x-\sqrt{\cos x+\sin x}=\cos ^{2} x} \\ {\sin x-\cos ^{2} x=\sqrt{\cos x+\sin x}} \\ {\sin ^{2} x+\cos ^{4} x-2 \sin x \cos ^{2} x=\cos x+\sin x} \\ {\sin ^{2} x+\cos ^{4} x-2 \sin x \cos ^{2} x-\cos x-\sin x=0} \\ {\sin ^{2} x+\cos ^{4} x-2 \sin x\left(1-\sin ^{2} x\right)-\cos x-\sin x=0} \\{\sin ^2}x + {\left( {1 - {{\sin }^2}x} \right)^2} - 2\sin x\left( {1 - {{\sin }^2}x} \right) - \cos x - \sin x = 0\\ {\sin ^{2} x+\sin ^{4} x-2 \sin ^{2} x+1-2 \sin x+2 \sin ^{3} x-\cos x-\sin x=0} \\ {\sin ^{4} x+2 \sin ^{3} x-\sin ^{2} x-3\sin x-\cos x+1=0}\end{array}  Now i think it gets more complicated , any help would be appreciated


How to format old disk after installing new boot disk?

I just installed a  as a Windows 10 boot drive on an Acer Aspire E15. The computer previously had Windows 10 installed on a 1 TB HDD.   This is what my current configuration looks like:    Disk 1 is the SSD boot drive running Windows 10. Currently, the EFI System Partition appears to be listed as a boot drive during restarts, which is a problem. How can I format Disk 0 (the old 1TB HDD) so that the drive contains a single partition with no strings attached?  I have tried the following DISKPART commands with no success (See errors below).   DISKPART> list disk    Disk ###  Status         Size     Free     Dyn  Gpt   --------  -------------  -------  -------  ---  --- * Disk 0    Online          931 GB  1041 MB        *   Disk 1    Online          232 GB      0 B        *  DISKPART> delete disk override  The disk you specified cannot be deleted. Please select an empty missing disk to delete.  DISKPART> list disk    Disk ###  Status         Size     Free     Dyn  Gpt   --------  -------------  -------  -------  ---  --- * Disk 0    Online          931 GB  1041 MB        *   Disk 1    Online          232 GB      0 B        *  DISKPART> clean  Virtual Disk Service error: Clean is not allowed on the disk containing the current boot, system, pagefile, crashdump or hibernation volume.


if $m,n,k$ are any three positive integers prove that $$(m,n)(m,k)(n,k)[m,n,k]^2=[m,n][m,k][n,k](m,n,k)^2$$ where $(a,b)$ denotes gcd of $a$ and $b$, $[a,b]$ denotes lcm of $a$ and $b$. I tried with the formula $(a,b)[a,b]=ab$


Extract reply addresses from all emails in an outlook folder (sent on behalf of)

I've got to send a bulk email out to a bunch of people in reply to emails they sent me. I've got all the original emails stored in a single outlook folder. I want to extract all of the reply addresses from the emails in that folder so I can send an email to all of them.  The article  shows you how to export the FROM address of these emails, however a large amount of them came from a web service that sends emails 'on behalf of' the person I'm trying to mail to. So I need the reply-to address, and the export wizard doesn't do that.  Does anyone have a tip on how to do this? This is Outlook 2007 on Exchange 2010.


I am trying to ask the user for two ints separated by a space. I also want to store the two separated numbers into two integer variables. Please help it is so simple I am having a hard time finding a good source for it.  System.out.print("Please enter 2 integers (separated by spaces): ");             String numbers = kb.nextLine();             kb.useDelimiter(" ");


Force adding certain page on the TOC without using \chapter* command

I want to include my cover page in the table of contents. Since, i'm not using \chapter{...} or \chapter*{...} to write the title. The reason is i put image logo on the top, so i won't use \chapter*{...}. But i  don't know how to add this page in the TOC. Maybe there is something like : \addcontentsline{toc}{page 1}{`covername`} ?  Please help and thanks!


I am trying to find x values for points along the normal distribution curve, and I ended up with a problem that goes back to the method of solving $x = \ln x$. Right now, I have $\ln(a \mu) - \ln(10) = \frac {-1} {2a^2} $. This is not something I know how to solve. I tried Googling this type of problem and nothing came up. How does one solve for a variable both inside and outside of a natural logorithm, specifically in the example problem above? Could anyone explain how this could be done?


Interpreting the Cross Section Ratio $R$

Below is experimental data for the ratio $$R=\frac{\sigma(e^+e^-\rightarrow hadrons)}{\sigma(e^+e^-\rightarrow\mu^+\mu^-)}$$ as a function of the centre of mass energy $\sqrt s$. I am interested in the peak at around $100GeV$ which corresponds to the resonance of the $Z^0$ boson. There are two ways of looking at this that I have in mind:  We can effectively ignore the electromagnetic process around this energy, and so each process should have it's own Breit-Wigner peak centred on the mass energy of the $Z^0$. The ratio of these is just a constant. Thinking in terms of Feynman rules and again ignoring the electromagnetic process around this region, each process has the same propagator and vertex factors (roughly - ignore quark mixing) and there are some extra factors due to different quarks being possible and colour degeneracy, but still the ratio should be a constant (one possible issue here is interference between Feynman diagrams which I have neglected?).  So my question is why does the peak exist in the data?


Export 3D model from Blender to .U3D for use in PDF file

.pdf files supports , you can view the model from any angle by mouse movements - sort of like looking through the viewport, only the object is fully rendered, "real", etc. This requires a .ud3 file. Blender does not export a .ud3 file. Any alternatives to achieve this?


There's something not quite right with the achievements drop down on stackexchange.com (All of the site icons are wrong)

I just checked my (meagre) achievements for today on  and got this:    Where as it should look like this:    The site icons are a bit awry.


How can photons destructively interfere?

This is a concept I don't fully understand. If I have two photons each with frequency $\nu$, then they each have an energy of $E = h\nu$. If they get matched with an inverted phase, then the summed wave will be null due to destructive interference. Then where does the energy go? It cannot radiate, since that would produce an extra E-M wave, right?


Wireframe shading issue in Blender 2.91 viewer

I'm new to Blender and I've been trying to get the wireframe shading to work since 2 days and been having this issue shown in the image below:  Whenever I try to go into wireframe shading mode it makes the object transparent. Things I have tried:  Uninstalling and reinstalling Blender. Loading factory settings. Turning on wireframe in overlay drop-down. Selecting wireframe in viewport display under object properties.  Any help regarding this issue is appreciated.


Calculating $\int_{- \infty}^{\infty} \frac{\sin x \,dx}{x+i} $

I'm having trouble calculating the integral  $$\int_{- \infty}^\infty \frac{\sin x}{x+i}\,dx $$  using residue calculus. I've previously encountered expressions of the form   $$\int_{- \infty}^\infty f(x) \sin x \,dx $$  where you would consider $f(z)e^{iz}$ on an appropriate contour (half circle), do away with the part of the contour that wasn't on the real axis by letting the radius go to infinity, then recover the imaginary part of the answer to get back the sine. However here, I can't replace the sine with $e^{iz}$ in my complex function because $$\operatorname{Im} \frac{e^{ix}}{x+i} \neq \frac{\sin x}{x+i}\cdots$$  How to remedy this? I'm not sure if substituting $\sin x = \frac{1}{2i}(e^{ix}-e^{-ix})$ and solving two integrals is how this problem is meant to be solved, although I'm 99% sure it would work


I'm having problems trying to find the pnp4nagios package. I don't know what to do.   apt-get install pnp4nagios -y


A proof for the identity $\sum_{n=r}^{\infty} {n \choose r}^{-1} = \frac{r}{r-1}$

Do you have any idea to prove the following identity via a combinatorial (or algebraic) method?  $\sum_{n=r}^{n=\infty} {n \choose r}^{-1} = \frac{r}{r-1}$  This is  of the book Chen C.C., Koh K.M. Principles and techniques in combinatorics. The book does not give a solution, although it mentions: "see H. W. Gould, Combinatorial Identities, Morgantown, W.V. (1972), 18-19".  many thanks in advance, Shahram


Is this an attempt at fraud/impersonation? stockoverflows.com

I just stumbled upon , which seems to be an attempt to impersonate the Stack Overflow website.   Should something be done about this? At first thought, I'm concerned about the possible attempt to steal login credentials. At the very least, there's a copyright infringement issue — of the site design and logo, if not of the CC content.  For what it's worth, the domain registrar is hiding behind whois privacy:  Domain Name: stockoverflows.com Registry Domain ID: 1927798280_DOMAIN_COM-VRSN Registrar WHOIS Server: whois.namesilo.com Registrar URL: https://www.namesilo.com/ Updated Date: 2016-03-28 Creation Date: 2015-05-11 Registrar Registration Expiration Date: 2016-05-11 Registrar: NameSilo, LLC Registrar IANA ID: 1479 Registrar Abuse Contact Email:  Registrar Abuse Contact Phone: +1.6024928198 Status: clientUpdateProhibited Status: clientRenewProhibited Status: clientDeleteProhibited Status: clientTransferProhibited Registry Registrant ID:  Registrant Name: Domain Administrator Registrant Organization: See PrivacyGuardian.org Registrant Street: 1928 E. Highland Ave. Ste F104 PMB# 255 Registrant City: Phoenix Registrant State/Province: AZ Registrant Postal Code: 85016 Registrant Country: US Registrant Phone: +1.3478717726 Registrant Phone Ext:  Registrant Fax:  Registrant Fax Ext:  Registrant Email: pw-39ff5aac5e30e92abbca1d2b54f52045@privacyguardian.org Registry Admin ID:  Admin Name: Domain Administrator Admin Organization: See PrivacyGuardian.org Admin Street: 1928 E. Highland Ave. Ste F104 PMB# 255 Admin City: Phoenix Admin State/Province: AZ Admin Postal Code: 85016 Admin Country: US Admin Phone: +1.3478717726 Admin Phone Ext:  Admin Fax:  Admin Fax Ext:  Admin Email: pw-39ff5aac5e30e92abbca1d2b54f52045@privacyguardian.org Registry Tech ID:  Tech Name: Domain Administrator Tech Organization: See PrivacyGuardian.org Tech Street: 1928 E. Highland Ave. Ste F104 PMB# 255 Tech City: Phoenix Tech State/Province: AZ Tech Postal Code: 85016 Tech Country: US Tech Phone: +1.3478717726 Tech Phone Ext:  Tech Fax:  Tech Fax Ext:  Tech Email: pw-39ff5aac5e30e92abbca1d2b54f52045@privacyguardian.org Name Server: PNS11.CLOUDNS.NET Name Server: PNS12.CLOUDNS.NET Name Server: PNS13.CLOUDNS.NET Name Server: PNS14.CLOUDNS.NET Name Server: PNS15.CLOUDNS.NET Name Server: PNS16.CLOUDNS.NET Name Server: PNS17.CLOUDNS.NET Name Server: PNS18.CLOUDNS.NET Name Server: PNS19.CLOUDNS.NET Name Server: PNS20.CLOUDNS.NET DNSSEC: unsigned URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/  Domains - cheap, easy, and secure at NameSilo.com  http://www.namesilo.com


Why are quadratic equations called quadratics?

The word "quad" generally means 4. Quadratics don't have 4 of anything. Can anyone explain where the name comes from?


How can I define a math operator behaving like \lim or \sum with limits?

I want to define \ext to behave exactly like \lim.  I tried \newcommand{\ext}{{\mathrm{ext}}\,} but that doesn't behave exactly like \lim.


Recently I've tried to join my friend's server on Minecraft without any success I don't have mods The version is 1.16.5 I have windows 10 The error is io.netty.channel.abstractchannel$annotatedconnectexception I've restarted my pc, my pc's wifi, I've restarted minecraft a few times, I've updated the java firewall stuff What can i do?


GIven Unencrypted and encrypted data (AES-GCM) both, is it possible to calculate the Chiper key of AES-GCM

Sorry for a simple curiosity, Given Unencrypted and encrypted data (AES-GCM) both, is it possible to calculate the Chiper key of AES-GCM ?


Does $M_n(R_1)\cong M_n(R_2)$ imply $R_1\cong R_2$?

Let $R_1,R_2$ be two rings with identity. If for some $n\in\mathbb N$, $M_n(R_1)$ and $M_n(R_2)$ are isomorphic as rings, can we deduce that $R_1\cong R_2$? I can prove it when both $R_1,R_2$ are local or commutative.


I have à request to display opportunities related to product object by using visualforce page on Product2


Can I cast spells in the middle of another spell resolving?

Say I had  and I used  on something, could I respond to Cloudshift bringing the creature back into play with  or something similar?


Why does size and used space in df output contradict available space

Running the following command:  $ df -h   Gives the following output:  Filesystem                        Size  Used Avail Use% Mounted on /dev/md2                           91G   85G  1.2G  99% /home   Which means out of the 91 total only 85 is used, which should leave 6 Avail (91 - 85 = 6). Why is Avail only 1.2?  This question is explicitly about the contradiction between the Used - Size and the Avail column in df output as opposed to a discrepancy between df and du output such as in . In my case there are no deleted files still in use on the filesystem.


Why not show (or make it optional) only hot questions in chosen communities?

It would be more convenient than having the costumers manually filtering them, and it's useful too. Similar question websites supports such features after all.


I used to see conditions like  if (something == 0){do it}, but  now I've met this sentence in iOS_Book   if (nil == s)   Is this the same as if (s == nil) and if not, what is the difference?


Just like we can check COM ports in windows 7 or lower , by going to  Control Panel >> Device Manager >> Ports   How should we  check it in Windows 10?


Give an example of a non-separable subspace of a separable space

I'm trying to find an example of a non-separable subspace of a separable space.  What kind of examples are there?


Help needed in a quiz question related to continuity of f'(x)

This question was asked in my real analysis quiz and I am unable to prove it true/ false.  State True/False -> Let f : $\mathbb{R}$-> $ \mathbb{ R} $ be a differentiable function. Then f'(x) is continuous.   I thought that f'(x) can be discontinuous as differentiability of f implies continuity of f not anything about f'(x) but I am unable to find an example. I tried sin(1/x) ,  cos(1/x) but it couldn't be such an example.


How to understand the analysis and execution principle of JavaScript

var a = 1; (function a(){     console.log('0:', b)     console.log('1:', a)     a = 100     var b = 2     console.log('2:', a)     console.log('3:', b) })(); console.log('4:', a)    How to understand the change process of 'a' in the function 'a'. Where is the value 100. For normal, pre-analysis and execution should like this: var any = 1 function any(){} pre-analysis process:  GLOBAL { any: undefined } GLOBAL { any: function any(){} }  execution process:  GLOBAL { any: 1 }  But you can't understand the 'a' above in this way. Could you please help me?


Interpreting a binomial regression model in R with cloglog link function

I have built a binomial regression model using the equation: logit_1 <- glm(past_adl_binary~., family = binomial(link = "cloglog"),                 data = newdata)  The outcome of the model is as follows:  Can anyone help me interpret the outcome of this model? I understand that all of the coefficients are significant apart from sunangle. Can I use this equation (100*exp(parameter estimate)-1) to calculate the increase/ decrease in percent probability of my y-variable (1 or 0) changing based on my predictor variables?  For example, for habitat_categoryONDEEP: 100*(exp(-0.173)-1) = -15.886.  Would this suggest that a habitat category of ONDEEP decreases the probability of my y-variable being 1 by 15.9%, compared to the reference category?


Another word for (sounds like) 'manual' labor/task

I remember a word that is spelled something like 'meanual' labor or work. It is supposed to mean not manual (physical) but just something which requires a lot of hard work and grinding.


Most shell scripts I use have syntax like   ./shellscript.sh -first_argument_flag <first_argument_value> -second_argument_flag <second_argument_value>   but all of the online resources for shell scripters only discuss passing positional arguments like  ./shellscript.sh <first_argument_value> <second_argument_value>    which are subsequently used in the script as "$1" , "$2", etc.   I would like to use the first, more user-friendly syntax rather than the positional argument syntax. As an example, suppose I want to echo a filename with flag -f and a directory with flag -d. Call this script echofd.sh. I want  ./echofd.sh -f myfile.txt -d /my/directory/    to produce the output  Your File is: myfile.txt  Your Directory is: /my/directory/   and regardless of which order -f and -d are positioned in calling the script.


Can I use a spell with a casting time of "Bonus Action" as my action?

I get that some spells are "especially swift" to cast and thus have a casting time of "Bonus Action". But is there any reason I couldn't cast such a spell as my Action?   Does it make a difference if the idea is for the one spell to be cast all by itself on a turn or if the desire is to use another Bonus Action (possibly a spell) on the same turn?


Can you wear armor and second skin to utilize multiple upgrade slots?

Can you wear 2 sets of armor to get the multiple upgrade slots? Ex. wearing a second skin under a defrex hide to get a total of 2 upgrade slots


Okay i can't download any app to my phone without it alway sayrERROR DOWNLOAD APP THERE IS INSUFFICIENT SPACE ON THE DEVICE. I'VE ONLY GOT 1 APP MYSELF DOWNLOAD TO MY PHONE IT CALKED VAULT FOR MY PICTURE SO HOW DO I FREE UP SPACE I'VE CLEAR A THE CACHE I HAVEN'T CLEAR THE DATA BECAUSE I DON'T KNOW IIF I'M SUPPOSED TO PLEASE HELP ME


Am I able to put uncooked chicken back in my fridge for a day?

I just took my chicken breast out of the packet and cut it up to make schnitzel then realised I had no oil. Is it safe to put it back in my fridge for a day?


How to get things off your head in Minecraft Mo' Creatures mod

I installed the Mo'Creatures mod into Minecraft, then made a fish bowl. After catching a fish I went to put it on top of a bookshelf in my room, but instead of placing it, the bowl just dropped at my feet. When I tried to pick it up my character put it on his head. Now I'm stuck with a fish bowl on my head and I can't find any mention anywhere of how to get it off. There are a number of other animals from the mod that you can put on your head for some effect, but no mention of how to remove them pretty much anywhere.


Probability that the equation so formed will have real roots

Three dice named A,B,C are thrown and the numbers shown on them are put for $a,b,c$ respectively in the quadratic equation $ax^2+bx+c=0$.What is the probability that the equation so formed will have real roots?    Since the roots are real.Therefore,$b^2\geq 4ac$  When $b=2$,then $a=1,c=1$;When $b=3$,then $a=2,c=1$;When $b=3$,then $a=1,c=1$ When $b=3$,then $a=1,c=2$;When $b=4$,then $a=2,c=2$;When $b=4$,then $a=1,c=4$ When $b=4$,then $a=4,c=1$;When $b=4$,then $a=1,c=3$;When $b=4$,then $a=3,c=1$ When $b=4$,then $a=1,c=2$;When $b=4$,then $a=2,c=1$;When $b=4$,then $a=1,c=1$ When $b=5$,then $a=2,c=3$;When $b=5$,then $a=3,c=2$;When $b=5$,then $a=5,c=1$ When $b=5$,then $a=1,c=5$;When $b=5$,then $a=2,c=2$;When $b=5$,then $a=3,c=1$ When $b=5$,then $a=1,c=3$;When $b=5$,then $a=2,c=1$;When $b=5$,then $a=1,c=2$ When $b=5$,then $a=1,c=1$;When $b=6$,then $a=3,c=3$;When $b=6$,then $a=2,c=4$ When $b=6$,then $a=4,c=2$;When $b=6$,then $a=2,c=3$;When $b=6$,then $a=3,c=2$ When $b=6$,then $a=5,c=1$;When $b=6$,then $a=1,c=5$;When $b=6$,then $a=2,c=2$ When $b=6$,then $a=3,c=1$;When $b=6$,then $a=1,c=3$;When $b=6$,then $a=2,c=1$ When $b=6$,then $a=1,c=2$;When $b=6$,then $a=1,c=1$  I have counted 35 cases and my probability is $\frac{35}{216}$,but in the book $\frac{43}{216}$ is the answer.  Which 8 cases i have left,i checked but could not find.Please help me.


What is precisely the role of the '&' character in a bash/shell redirection?

So as I'm writing my own shell for school, I have to implement redirections.  I've looked at the GNU Bash manual, and a fair amount of tutorials, but I'm still having troubles understanding what exactly means the ampersand in these redirections. I know when I have to use them when using simple redirections, like &>file or 2>&- but I don't get the precise meaning of it.   Could someone explain?


I want to add a symbolic link to another folder I want to say ln -sf / var / www / html to /home / var / exemple / public This is good. / home / var / example / public belongs to a user who creates. in any case this is fine to do in production


How to solve a Distance-Speed question where speed and distance are given but have to find a specific point in time?

The distance between Town A and Town B is 450km. Guy A travels from Town A to B at the speed of 80km/h; while Guy B travels from Town B to Town A at the speed of 70km/h. When will Guy A and Guy B meet, if both of them started at the same time?  I don't really understand where to start with. Help!


I read somewhere that this can be used for the reverse polarity protection in the circuit. But I am quite confused with its operation. Can somebody help me with this.         – Schematic created using


Entry to The US before 30-day grace period for student visa

The F student visa allows me to enter the US up to 30 days before the program starts. For starting to set up things it is of my interest to arrive sooner than that. How hard is it to travel there beforehand with a tourist visa (waiver) and leave to, say Mexico, to then re enter on a proper date within the 30 days with the student visa? This seems easier than requesting for a status change inside the US from tourist to student..


Can a warlock with the UA Raven Queen patron cast spells on targets that they can only see using their Sentinel Raven's sight?

A  not only grants me a Sentinel Raven, but also the handy ability to see through its eyes.  Unlike the telepathic connection with a regular familiar, I don't have to use an action to do so.    If I am blinded, but my Sentinel Raven is not (and within telepathic range), can I use my raven's sight to cast spells that require me to see my target? Would this negate any disadvantage resulting from me being blinded? Or would I still suffer disadvantage, for example, because I have to cast from my raven's perspective and not my own point of view?


Is it possible to have a singularity with zero mass?

A singularity, by the definition I know, is a point in space with infinite of a property such as density.  Density is Mass/Volume.  Since the volume of a singularity is 0, then the density will thus become infinite because Mass/0 = undefined  However, is it possible to have a singularity with a mass of 0? 0/0 is indeterminate, but would it be possible for a singularity to exist even if its mass and volume were zero?


Achieving Flat-End line buffers in QGIS?

I need to buffer a series of lines by 40m, however I only want the buffer to come off the sides and not off either end of the line.  I know in ArcGIS there is a "flat-ends" tickbox that achieves exactly this, however unfortunately I can't use ArcGIS at this current time.  Is there any way to achieve this in QGIS?   I've had a look at some of the work arounds, but due to the scale of my datasets (national road networks) none of the ones I have found so far are feasible.


Java will not recognize "(" and ")" strings

I am trying to interpret a string input from the user. I take in a phrase, split it into an array, and compare each value in the array to ")" as a boolean. The problem is it will read the string "( 3 + 5 )", and I know that the array that takes in the string is ["(","3","+","5",")"] and when I print out position 0 and 4 of the array, it returns "(" and ")". I know that these are type string of length 1, however, when I compare the exact same values to the "(" ")" in the code, it returns false.  Any idea what's wrong? Here's my code. The parts that I am having trouble with are the if statements.      public String buildExpression(String E){         String[] exprArr=E.split(" ");               int len=exprArr.length;         BTStacker S = new BTStacker();         String val;         for (int i=0; i<len; i++){             val=exprArr[i];             System.out.println(val);             if (val=="("){                 System.out.println("2");             }             else if(val != ")"){                 BSTree T=new BSTree();                 BSTNode v=new BSTNode(val,null);                 T.addRoot(v);                 S.push(T);             }             else{                 BSTree Ty = S.pop();                 BSTree T=S.pop();                 BSTree Tx=S.pop();                 T.attach(T.root(),Tx,Ty);                 S.push(T);             }          }     }


What do atomic orbitals represent in quantum mechanics?

I am learning the basics of quantum mechanics and am familiar with the Schrödinger equation and its solution, but I was confused about what the familiar atomic orbital shapes represent? Do they represent nothing physical and are just plots of the wavefunction in 3D polar co-ordinates? Or do they represent the region where probability of finding an electron is $90\%$? Or something else? Levine 7th ed. states that  An atomic orbital is just the wavefunction of the electron  Wikipedia instead states that  In atomic theory and quantum mechanics, an atomic orbital is a mathematical function describing the location and wave-like behavior of an electron in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus. The term atomic orbital may also refer to the physical region or space where the electron can be calculated to be present, as predicted by the particular mathematical form of the orbital


"for which 'blah blah'" vs. "which 'blah blah' for"

When is it appropriate to use "for which" instead of "which .. for"?  e.g. (talking about webpages)     This method is useful for deprecated pages for which users have made bookmarks   vs     This method is useful for deprecated pages which users have made bookmarks for   My instinct is that both sentences are semantically the same. The first example seems a little archaic, and it seems to clash with my prior use of "for". However, the second example doesn't seem to emphasis that the bookmark is for the deprecated page.  Is there any meaningful difference? Which should I prefer, and it what other circumstances should I use one over the other?  Thanks for reading


How do i uninstall Mac OS after installing Ubuntu

I've decided to uninstall Mac OS from my MacBook Pro.  How do I remove the OSX partition after installing it with rEFInd?


How can I inject a service class properly without getting nullpointer exception?

I'm working on a Spring Boot application and I'm trying to inject my UserService class into my TenantIdentifierResolver class because I want to use the createUser() method. However i get a nullpointer exception. For some reason userService is set to null, what am I missing here? @Component public class TenantIdentifierResolver implements CurrentTenantIdentifierResolver {      public static final String DEFAULT_TENANT = "default_schema";      private UserService userService;      @Override     public String resolveCurrentTenantIdentifier() {         String tenant =  TenantContext.getCurrentTenant();         if(tenant != null){             userService.createUser(tenant);             return tenant;         } else {             return DEFAULT_TENANT;         }     }      @Override     public boolean validateExistingCurrentSessions() {         return true;     } }  I've tried to use @Autowired or make a constructor injection but then I got this error: The dependencies of some of the beans in the application context form a cycle: ┌─────┐ |  entityManagerFactory defined in class path resource [org/example/membership/config/HibernateConfig.class] ↑     ↓ |  tenantIdentifierResolver (field private org.example.membership.service.UserService org.example.membership.multitenancy.TenantIdentifierResolver.userService) ↑     ↓ |  userService defined in file [C:\project\Member\server\target\classes\org\example\membership\service\UserService.class] ↑     ↓ |  userRepository defined in org.example.membership.repository.UserRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration ↑     ↓ |  (inner bean)#18957a3d └─────┘  This is my UserService class @Service public class UserService {      private UserRepository userRepository;     private TenantService tenantService;      public UserService(UserRepository repository, TenantService tenantService) {         this.userRepository = repository;         this.tenantService = tenantService;     }      @Transactional     public User createUser(String tenant) {         Tenant tenant = new Tenant();         tenant.setTenantName(tenant);         tenantService.initDatabase(tenant);         return tenant ;     } }  This is my HibernateConfig class @Configuration public class HibernateConfig {     @Autowired     private JpaProperties jpaProperties;      @Bean     JpaVendorAdapter jpaVendorAdapter() {         return new HibernateJpaVendorAdapter();     }          @Bean         LocalContainerEntityManagerFactoryBean entityManagerFactory(         DataSource dataSource,         MultiTenantConnectionProvider multiTenantConnectionProviderImpl,         CurrentTenantIdentifierResolver currentTenantIdentifierResolverImpl     ) {          Map<String, Object> jpaPropertiesMap = new HashMap<>(jpaProperties.getProperties());       jpaPropertiesMap.put(Environment.MULTI_TENANT, MultiTenancyStrategy.SCHEMA);       jpaPropertiesMap.put(Environment.MULTI_TENANT_CONNECTION_PROVIDER, multiTenantConnectionProviderImpl);              jpaPropertiesMap.put(Environment.MULTI_TENANT_IDENTIFIER_RESOLVER, currentTenantIdentifierResolverImpl);          LocalContainerEntityManagerFactoryBean em = new  LocalContainerEntityManagerFactoryBean();         em.setDataSource(dataSource);         em.setPackagesToScan("org.example*");         em.setJpaVendorAdapter(this.jpaVendorAdapter());         em.setJpaPropertyMap(jpaPropertiesMap);         return em;     } }


In which kind of Journal should i publish my math applied based paper regarding a political problem?

I'm currently working on a voting analysis paper, most of the theory is about, "math", i'm talking about linear algebra, programming, big data, and that specific knowledge area, however the paper is all oriented into  a specific problem regarding politics as it's entirely related to voting analysis and stablishing political networks based on it, so to which kind of journal would be better to send it in order to get published, one of applied math, or one of political science. i've check and it meets requirements of both journals.  Which are the advantages of publishing on one instead of the other?


I have a polyline feature class and a polygon feature class. I would like to clip the extent of the polyline which are NOT overlaid on the polygon.   How can I do that?  I should be looking for similar tool as intersect, but intersect clips the polyline that overlaid on the polygon. I want an opposite of that.


Prove convexity of $f(x)=\sum_{i=1}^{n}{x_i\ln{x_i}}-\left(\sum_{i=1}^{n}{x_i}\right)\ln\left(\sum_{i=1}^{n}{x_i}\right)$ over $\mathbb{R}_{++}^n$

Prove convexity of $$f(x)=\sum_{i=1}^{n}{x_i\ln{x_i}}-\left(\sum_{i=1}^{n}{x_i}\right)\ln\left(\sum_{i=1}^{n}{x_i}\right)$$ over $\mathbb{R}_{++}^n$.  I found the gradient and the Hessian of $f(x)$, but didn't manage to prove $\nabla^2f(x)\succeq0$. Any other method (using convexity rules etc.) accepted as well. $$\frac{\partial{f}}{\partial x_i}=\ln(x_i)-\ln\left(\sum{x_i}\right)$$ $$\frac{\partial^2{f}}{\partial x_i x_j}= \begin{cases}        \frac{1}{x_i} - \frac{1}{\sum{x_i}} &\quad \text{if }i=j\\        \frac{1}{\sum{x_i}} &\quad \text{if }i\neq j\\      \end{cases}$$ Please advise. Thank you. Edit: While trying to prove that $A=\nabla^2f(x)\succeq0$, the expension of $y^TAy$ that I got is: $$y^TAy=\sum_{i=1}^{n}{\frac{y_i^2}{x_i}}-\frac{1}{\sum_{i=1}^{n}{x_i}} \sum_{i \neq j}{y_i y_j}$$ One possible way of proving convexity is showing $y^TAy\geq0$ for any $y \in \mathbb{R^n_{++}}$.


Backup Subversion Repositories with rsync

Is it ok to Synchronize the SVN Repository directory using the rsync command. Will there be any issues, will the repository files get corrupted due to this? (I use rsync only when no one is using the repositories).


What does recursive cosine sequence converge to?

I have a sequence defined as follow:  $a_0 = 1, a_n=\cos\left(a_{n-1}\right)$.  I want to count $\lim_{n\rightarrow\infty} a_n$ - it definitely does have limit by looking at the graph, the first few numbers of the limit are 0.7390851, but I have no idea, if that number is related to some other real number ($\pi$ or something like that).  The sequence is from , but they don't provide actual result for their own sequence.


How to determine best cutoff point and its confidence interval using ROC curve in R?

I have the data of a test that could be used to distinguish normal and tumor cells. According to ROC curve it looks good for this purpose (area under curve is 0.9):    My questions are:    How to determine cutoff point for this test and its confidence interval where readings should be judged as ambiguous? What is the best way to visualize this (using ggplot2)?   Graph is rendered using ROCR and ggplot2 packages:  #install.packages("ggplot2","ROCR","verification") #if not installed yet library("ggplot2") library("ROCR") library("verification") d <-read.csv2("data.csv", sep=";") pred <- with(d,prediction(x,test)) perf <- performance(pred,"tpr", "fpr") auc <-performance(pred, measure = "auc")@y.values[[1]] rd <- data.frame(x=perf@x.values[[1]],y=perf@y.values[[1]]) p <- ggplot(rd,aes(x=x,y=y)) + geom_path(size=1) p <- p + geom_segment(aes(x=0,y=0,xend=1,yend=1),colour="black",linetype= 2) p <- p + geom_text(aes(x=1, y= 0, hjust=1, vjust=0, label=paste(sep = "", "AUC = ",round(auc,3) )),colour="black",size=4) p <- p + scale_x_continuous(name= "False positive rate") p <- p + scale_y_continuous(name= "True positive rate") p <- p + opts(             axis.text.x = theme_text(size = 10),             axis.text.y = theme_text(size = 10),             axis.title.x = theme_text(size = 12,face = "italic"),             axis.title.y = theme_text(size = 12,face = "italic",angle=90),             legend.position = "none",             legend.title = theme_blank(),             panel.background = theme_blank(),             panel.grid.minor = theme_blank(),              panel.grid.major = theme_line(colour='grey'),             plot.background = theme_blank()             ) p   data.csv contains the following data:  x;group;order;test 56;Tumor;1;1 55;Tumor;1;1 52;Tumor;1;1 60;Tumor;1;1 54;Tumor;1;1 43;Tumor;1;1 52;Tumor;1;1 57;Tumor;1;1 50;Tumor;1;1 34;Tumor;1;1 24;Normal;2;0 34;Normal;2;0 22;Normal;2;0 32;Normal;2;0 25;Normal;2;0 23;Normal;2;0 23;Normal;2;0 19;Normal;2;0 56;Normal;2;0 44;Normal;2;0


Determinant of a block lower triangular matrix

I'm trying to prove the following: Let $A$ be a  $k\times k$ matrix, let $D$ have size $n\times n$, and $C$ have size $n\times k$. Then,  $$\det\left(\begin{array}{cc} A&0\\ C&D \end{array}\right) = \det(A)\det(D).$$  Can I just say that $AD - 0C = AD$, and I'm done?


What to know to start learning Quantum Mechanics

I am very interested in Quantum Mechanics, and I want to start learning some of the mathematics behind it - the simplification first, of course. What kind of mathematical ideas do I need to know and understand to follow along (e.g. Calculus, etc...). I'm sure that there is a huge list, but what are the main ones?


Microsoft silverlight not in Ubuntu 13.04 Netflix desktop app

I thought it would be fun to put Ubuntu 13.04 64-bit on my PC, I have been told Netflix would work on 64-bit, bit it didn't. I checked terminal, long story short with 64-bit was I don't know what foreign architecture support and I don't know how to use it. I dual operated it with Ubuntu 13.04 32-bit and got the Netflix desktop app and now I need Microsoft silverlight. Please help me I am at my witts end. I need to know how to use netflix on Ubuntu 13.04 32 or 64 bit (terminal says i386 in foreign architecture support in 64-bit). thanks


why does this regex lead to catastrophic backtracking?

I'm trying to match everything after the first occurrence of a table element and before closing a body tag in an html document.  This is the regex that I tried with:  (?:<table>(.|\s)*<\/table>)((.|\s)*)(?:<\/body>)   I got no matches for this regex.  I'm using JavaScript.    When I switch to PHP mode on regex101.com, I notice that this regex leads to catastrophic backtracking.  I've isolated the section that breaks it, and apparently it's this:  <table>(.|\s)*<\/table>   What's wrong with this expression?


Word for someone who is driven by morality

I'm looking for a word to describe someone who is very driven by morality, constantly trying to do what they believe is morally right.  This word would be used in a sentence like "I really admire her; she truly is a (...) person."


I have an enum with values like this (the example just shows a few of the values but you will catch on): _800, _830, _900, _24HOURS, CLOSED  These have a corresponding value, so I added to my enum, which you can do in Java, a value field and a getter and setter for the value, like this (for space sake I do not show the getter and setter but they are the standard ones):   enum Hours {     _800("08:00"),     _830("08:30"),     CLOSED("Closed"),     APPT("By Appt.")     // etc     ;      Hours(String v) {         val = v;     }     String val;  }   I also want to be able to go the other direction, that is, if I have a value (e.g. "08:00") I want it to return the enum _800.  So to the enum I added a map:   static Map<String,String> valToEnumMap = new HashMap();   then I added this to my constructor:      Hours(String v) {         val = v;         valToEnumMap.put(v, this);     }   and a new method:  Hours valToEnum(String v) {    return valToEnumMap(v); }   but when I try running it I get an initialization error at the point where it tries to insert into the map.  I have tried other things like   valToEnumMap.put(v, valueOf(name());   but the same error.  I did find a workaround but it is very slow, so I wonder what I did wrong?  Here is the workaround I used which is slow:  public static OfficeHoursTimes valToEnum(String val) {         for (OfficeHoursTimes o : OfficeHoursTimes.values()) {             if (o.getVal().equals(val)) {                   return o;             }         }         return null; }   But there has to be a better way


Wiping Windows 7 with Ubuntu 14.04 installed

Is it possible for me to wipe my Windows 7 partition (and then re-install W7)?? I already have 14.04 installed and whilst I still want to have Windows on my machine, I have all my data backed up and I no longer need the data on the Windows partition. Is this doable?  Thanks!


Compactly supported continuous function is uniformly continuous

Let $f:\mathbb R \rightarrow \mathbb R$ be continuous and compactly supported. How can I prove that $f$ is uniformly continuous ? I was trying to prove it by contradiction but get stuck. My attempt was as follows:  Let $E$ be the compact support of $f$. On $E$ we know that $f$ is uniformly continuous. If we assume that $f$ is not uniformly continuous we know $$ \exists \epsilon > 0 \forall \delta > 0 \exists x,y \in \mathbb R: |x-y|<\delta \wedge |f(x)-f(y)| \geq \epsilon $$ Let $\delta_n := \frac 1n$ and fix this $\epsilon > 0$. Compute a $\delta > 0$ s.t. $\forall x,y \in E:|x-y| < \delta \rightarrow |f(x)-f(y)| <\epsilon$. Let $n \geq N$ s.t. $\frac 1N < \delta$. Then we may assume wlog that $x_n \in E$ and $y_n \in \mathbb R \setminus E$ wehere $x_n,y_n$ are the points corresponding with $\delta_n$. This gives a sequence of points where $|x_n-y_n| \rightarrow 0$ and $x_n \in E$ and $y_n \in \mathbb R \setminus E$.  I now want to use somehow the continuitiy of $f$. How can I do this ? Is this approach a good one ? Can it be more simple ?  New idea: I know that $E$ is compact so $(y_n)_{n=0}^\infty$ has a convergent subsequence $(y_{n_j})_{j=0}^\infty$ whit limit say $y \in E$. Now  $$  |x_{n_j}-y| \leq |x_{n_j}-y_{n_j}|+|y_{n_j}+y| \rightarrow 0 $$ So I can take $x_{n_j}$ close to $y$ to get $|f(x_{n_j})-f(y)| = |f(y)| <\frac \epsilon 2$ by the continuity. I can also take $y_{n_j}$ close to $y$ to get $|f(y_{n_j})-f(y)| <\frac \epsilon 2$. We further have $$  |f(y_{n_j})| \leq |f(y_{n_j})-f(y)| + |f(y)| $$ s.t. $$   |f(y)| \geq |f(y_{n_j})| - |f(y_{n_j})-f(y)| \geq \frac \epsilon 2 $$ because $|f(y_{n_j})| \geq \epsilon$ per construction. So we have $|f(y)| \leq \frac \epsilon 2$ and $|f(y)| > \frac \epsilon 2$ which is a contradiction.    New solution: Let $\epsilon > 0$. Let $\delta_1$ for the uniform continuity on $E$. Further $$  \forall x \in E,\ \exists \delta_x > 0\ \forall y \in \mathbb{R}: |x-y|< \delta_x \rightarrow |f(x)-f(y)| < \epsilon $$ Compute an open finite over of $E$ $$  E \subseteq \bigcup_{i=1}^N B\left(x_i,\frac{\delta_{x_i}}2\right) $$ Write $\delta_i := \delta_{x_i}$. Let $\delta_2 := \min_{i=1,\cdots,N} \frac {\delta_i} 2$ and $\delta := \min(\delta_1,\delta_2)$.   Assume $|x-y|< \delta$. If $x,y \in E$ or $x,y \notin E$ we are done. Otherwise assume $x \in E$ and $y \notin E$. Then $x \in B\left(x_i,\frac{\delta_i}{2}\right)$ for some $i$. Further $$  |y-x_i| \leq |y-x|+|x-x_i|\leq \delta_2 + \frac{\delta_i}2 \leq \delta_i $$ thus $y \in B(x_i,\delta_i)$ which proves the claim.


What is "total" in the output of "ls" command?

I have an empty directory. I am using following command to view the contents of that directory. ls -lart  The output I get is below. total 12 drwxr-xr-x 5 root  root  4096 Oct  2 12:26 .. drwxr-xr-x 2 apx   aim   4096 Nov 29 18:40 .  I don't have any files in this directory, then what counts out to 12 here (total 12)?


attr_accessor isn't working for variable setting in Ruby class

I was trying to get an understanding of Ruby classes and the auto generated getters and setters that come with attr_accessor. How come for the code below, I'm able to get it but not set it? Moreover, setting works for my store instance variable later in code (not shown). From what I , it seems with an attr_accessor I should be ble to read and write.   class HashMap     attr_accessor :store, :num_filled_buckets, :total_entries      def initialize(num_buckets=256)         @store = []         @num_filled_buckets = 0         @total_entries = 0         (0...num_buckets).each do |i|             @store.push([])         end         @store     end      def set(key, value)         bucket = get_bucket(key)         i, k, v = get_slot(key)          if i >= 0             bucket[i] = [key, value]         else             p num_filled_buckets # <- this works             num_filled_buckets = num_filled_buckets + 1 if i == -1 # this does not             # spits out NoMethodError: undefined method `+' for nil:NilClass             total_entries += 1             bucket.push([key, value])         end     end ...


Exclude questions with ignored tag in subscribed tag email

I'm subscribed to a tag. But I also ignore a tag. The two are sometimes used together, and I don't want to get the question(s) with the tag I ignore to my mail box in that case.  Please exclude those questions from the mail, and if this cause no questions to match, don't send any mail.


I do not know why it returns the Call to a member function fetchAll() on a non-object error because I am using the fetchAll method on the _sth object.  Does anybody know why it does this?  FormValidator PHP  $users = $this->_db->query("SELECT * FROM $ruleValue WHERE $input = ?", array($inputValue)); if($users->count()) {     $this->addError($input, $rule); }   Method  public function query($sql, $params = array()) {     $this->_sth = $this->_dbh->prepare($sql);      if($this->_sth = $this->_sth->execute($params)) {         return $this->_sth->fetchAll(PDO::FETCH_OBJ);     }      return false; }


Let $a \in \Bbb{Z} _{\ge2}$ . Suppose that for all m,n $\in \Bbb{Z}^+$ if $a | mn$, then $a | m$ or $a | n$. Prove that a is a prime number

to prove that a is a prime number, I need to show that a only has 2 divisors: 1 and itself. My approach to this question is to use the definition of divisibility and the hint in the question that since $a = k(mn)$, a will either be $a = i(m)$ or $a = j(n)$ (where i, j, k are constants) to show that either m and n either has to be a or 1. I'm not sure if the approach I'm taking is a correct/logical one.


ADB detects my device but fastboot doesn't

i am wanting to unlock the bootloader on my Samsung Galaxy A5 2017. The problem that I have encountered is that fastboot doesn't actually detect my device but adb does!  I have tried 'adb devices' and that finds my device but when i try 'fastboot devices' it doesn't appear with anything.  If you have any solutions please tell me!


I was looking for an answer for this problem in terms of matrices, but I really don't know how to prove this result. The proposition says that:  Let $A\in M_{m\times k}(\mathbb{C})$, $B\in M_{k\times p}(\mathbb{C})$ and $C\in M_{p\times n}(\mathbb{C})$, then $\textrm{rank}(AB)+\textrm{rank}(BC)\leq \textrm{rank}(B)+\textrm{rank}(ABC)$


How to automatically create Windows thumbnails recursively?

I am using Windows 8.1 with Windows Explorer. The image cache ("thumbs.db") is created when I visit a folder containing video, photo, or other such files. I have a problem with this because I have multiple folders with large videos and photos that are constantly changing. Every time I open a folder containing these files I have to wait several seconds until the thumbnail cache is created.   One workaround would be to disable the thumbnail cache. But I like to see thumbnails so this is not a solution for me. Instead, I would like to call a batch or another program every x-seconds that creates the Windows thumbnails recursively. I could then open the folders without delay.  How can I accomplish this?


If I SSH into a server via terminal and start a process to copy files, is it killed after I log out?

And if so, can it be kept alive somehow?  (This is not a duplicate question since I did not know that logging out will kill a process. Maybe others also don't and so ask the wrong question.   I would suggest that the answers include a link to the other .)


On creating a new bank account for "sugar payments"

Recently, I became a sugar baby and found a daddy who wants me to create a new bank account for him to send money to. He doesn’t want to use a cash app because he has been scammed in the past.  Is this a scam?  Is it normal to create a new bank account?  Would he be able to see my location?


I am struggling with a Bad Math Delimiter error, could I please ask for some help with this issue?   \documentclass{article} \usepackage[utf8]{inputenc}  \usepackage{setspace} \usepackage{mathrsfs}  \usepackage{amsmath} \usepackage{graphicx} \usepackage{multirow} \usepackage{eurosym} \usepackage{amstext} \usepackage{hyperref} \usepackage{grffile} %Stops the file name of figures appearing \usepackage{color} \usepackage{mathabx} \usepackage{float} \usepackage{pdfpages} \DeclareRobustCommand{\officialeuro}{%   \ifmmode\expandafter\text\fi   {\fontencoding{U}\fontfamily{eurosym}\selectfont e}}  \title{UCFB Diss} \author{danrawly} \date{}   \title{Dissertation} \author{} \onehalfspacing \usepackage{algorithmic}  \renewcommand{\familydefault}{\sfdefault} \textheight=23cm \textwidth=16cm \topmargin=-2cm \oddsidemargin=0cm \parindent=0mm \pretolerance=2000 \tolerance=3000  \begin{document}    $$t= \dfrac{(\bar{x_1}-\bar{x_2})}{\sqrt{\dfrac{S_1^2}{N_1} +\dfrac{S_2^2}{N_2}}}\)$$  \end{document}   Thank you in advance


Shall I accept an answer that answers part of my question?

So I bet you all met into a scenario, where someone wrote a good, detailed answer which answers part (or most, or the core) of your question. Then should you mark it as accepted? Or should you just don't accept it immediately, and wait if he updates the question or other better answers are written. As a question which's marked with an accepted answer might make people don't click into it.


How can I find out the number of seconds since 1970 using DateTime in C#

I am currently using this code:   var stringSecsNow = DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1)).TotalSeconds.ToString();   But is there some other way. I seem to recall in another language that there was an easier way to do this?


We can see who earned the most reputation in the current week, current month, current quarter, current year or all time. There is this  for that. Also see the below screenshot.    What struck me as odd was the different users for the Mathematics site. So I clicked on the picture that is listed as top user for the current year, which led me . Also see the below screenshot:    Here a different user is shown as the top user for 2019 when compared to the overall overview. I suspect the week or month listing to be somewhat volatile, but the difference between both users in this case is so big I can hardly blame caching.


Is a bank statement needed to apply for a German visa if I have an invitation?

I want to know that will it still be necessary for me to sent my bank statement to the Germany embassy for schengen visa , whilst i received a invatation from the one inviting me from Germany ?


With arrays, why is it the case that a[5] == 5[a]?

As Joel points out in , in  (aka: K & R), there is mention of this property of arrays in C: a[5] == 5[a]  Joel says that it's because of pointer arithmetic but I still don't understand. Why does a[5] == 5[a]?


In this question, I assumed the two side strings will also move with velocity $u$ and broke the vectors along the direction of motion of M and I got the velocity of the mass as $u\cos\theta +u\cos\theta = 2u\cos\theta$. (Both velocities of the two strings vector resolved and added) But the answer was wrong, as they broke the velocity of the mass, say $v$, into $v\cos\theta$ along the direction of the string and equated $$v\cos\theta = u$$ $$v=u\sec\theta$$ However, I do not find why my method of approach is wrong and why theirs should be correct. Please explain. Thank You!


Is green board or cement board required on shower/tub walls in massachusetts?


Find the number of zeroes of $p(z)=z^6+z^3+10z^2+4z+3$ inside the annulus $1<|z|<2$

Find the number of zeroes (counting multiplicity) of $p(z)=z^6+z^3+10z^2+4z+3$ inside the annulus $1<|z|<2$. I think this can be solved using Rouché’s theorem. First consider $|z|\leq 1$ on the boundary $|z|=1$ and $|z^6+z^3|<|10z^2+4z+3|$ which can be shown using triangle inequalities, the left side is at most $2$ while right side is at least $3$. We could also consider $|z|\leq 1+ \epsilon$ and our proof still works. Thus $p(z)$ has 2 roots inside $|z|\leq 1$. Also for $|z|= 2$ we have $|z^6+z^3|>|10z^2+4z+3|$. Thus we have 6 zeroes of $p(z)$ inside $|z|<2$ and therefore 4 of them are in $1<|z|<2$. Is this correct? The only "tricky" part is ruling out that there are zeros on $|z|=1$.