Evans Partial Differential Equations chapter 7 exercise 10 (uniqueness of regular solutions to the telegraph equation)

I would like to know how to solve exercise $10$ of chapter 7 of Evans' Partial Differential Equations, second edition. The problem goes like this:  Suppose $U\subset\mathbb{R}^n$ is an open and bounded set with smooth boundary, and $T>0$. Show there exists at most one smooth solution of this initial/boundary-value problem for the telegraph equation $$\begin{cases} u_{tt}+du_t-u_{xx}=f&\text{ in }(0,1)\times(0,T)\\ u=0&\text{ on }(\{0\}\times[0,T])\cup(\{1\}\times[0,T])\\ u=g,u_t=h&\text{ on }[0,1]\times\{t=0\} \end{cases}$$  I have no idea of what shall I do... if we suppose $u$ and $v$ are regular solutions of the given problem, then $u-v$ is a regular solution to the following problem $$\begin{cases} u_{tt}+du_t-u_{xx}=0&\text{ in }(0,1)\times(0,T)\\ u=0&\text{ on }(\{0\}\times[0,T])\cup(\{1\}\times[0,T])\\ u=0,u_t=0&\text{ on }[0,1]\times\{t=0\} \end{cases}$$ However, I don't know how to prove that any regular solution to the last problem must be identically zero in $(0,1)\times(0,T)$... I think the best way to proceed would be to make some change of variables in order to get rid of the term in $u_t$ above, and get some hyperbollic problem. I am completely lost, so any help will be appreciated.


I'm beginning Pathfinder and I'm curious as to how reliable the information is on that site.    I only ask because occasionally I find it is lacking sources and I know it also has some 3rd party items on the site as well and I don't know if any of that ever seeps into the mechanics.  thank you!


I want to send screenshots and images in chat. How can I achieve that?


Is $\mathbb{R}\setminus\{0\}$ endowed with $d(x,y)=|\frac{1}{x}-\frac{1}{y}|$ complete?

Consider $\mathbb{R}^*=\mathbb{R}\setminus\{0\}$ and let $d:\mathbb{R}^{*}\times\mathbb{R}^*\to [0,+\infty[$ the function defined as $d(x,y)=|\frac{1}{x}-\frac{1}{y}|$.  Is the metric space $(\mathbb{R}^*,d)$ complete? If I have the following sequence $\{n\}_{n\in\mathbb{N}}$ it does not converge once $\lim_{n\to\infty} \frac{1}{n}=0$ but $0\notin\mathbb{R}^*$ I have the above idea but I do not think is enough. Question: Can someone provide a proof for this statement? Is $(\mathbb{R},d)$ complete? Thanks in advance!


I was just answering a  and saw this:  As you can see, there is no name in the third comment. What's this?


Placement of original author and editor are swapped compared to web

In browsers the author of a question is to the far right at the bottom and anyone who has edited the question is shown to the left of that. In the app those two have swapped places, creating unnecessary opportunities for confusion due to habit.    App Version: 1.6.2.5 Device: iPhone 5 (Global) OS Version: Version 10.2 (Build 14C92)


I was allotted spectacles when I was in class 1.My lens power was then $-1$.Now after 12years it has became three times.I don't get why my lens power is increasing at such a fast rate.One reason I feel is use of computers and smartphones.I try to avoid them but it is a important part of my study.I fear if this continues I will be blind one day.Can anyone please suggest some measures I could take to avoid this.Please note I donot want to undertake a operation and wear contact lenses.Thanks.


Is there a way to cat files as they are created?

Unlike the answer to this question () I want to be able to see content of files that haven't been created yet as or after they are created.  I don't know when they will be created or what they will be named.  That solution is for a specific file and actually mentions in the question title creating a "hook" to a specific file.  My question is different because I don't want to hook anything, and what I do want is not specific to a particular file.  My question's title specifies "..as they are created" which should be a clue that the files I am interested in do not exist yet.  I have an application that users use to submit information from a website.  My code creates output files when the user is finished.  I want to be able to see the content of these files as they are created, similar to the way tail -f works, but I don't know ahead of time what the filenames will be.  Is there a way to cat files as they are created or would I have to somehow create an endless loop that uses find with the -newermt flag  Something like this is the best I can come up with so far:  #!/bin/bash # news.sh  while true do   d=$(date +"%T Today")   sleep 10   find . -newermt "$d" -exec head {} + done   For clarification, I don't necessarily need to tail the files.  Once they are created and closed, they will not be re-opened.  Existing files will never change and get a new modification time, and so I am not interested in them.


Help me learn to be a Salesforce Developer

I am a fresher and planning to make my career in Salesforce. I really need help from experts.  What is the requirements and what should i know to become a salesforce developer?I am currently working as Java developer


Does there exist a non constant entire function $f: \mathbb C \to \mathbb C$ which is square integrable?

Does there exist a non constant entire function $f: \mathbb C \to \mathbb C$ which is  i.e. $\int_{\mathbb C} \vert f(z)\vert^2 dz< \infty$ ?   I think that answer to above question is no and this should be direct application(probably by power series expansion of $f$) of some theorem but i am unable to solve this.Any ideas?


I have a small problem with the \column command in the beamer class.   Up to now, it has worked perfectly but somehow a problem with the spacing has appeared.  \documentclass{beamer}  \begin{document}  \begin{frame}[fragile]  \frametitle{Argumente}  \begin{columns}[c] % The "c" option specifies centered vertical alignment while the "t" option is used for top vertical alignment      \column{.45\textwidth} % Left column and width     \centering \textbf{Pro}     \vspace{0.2cm}      \begin{itemize}         \item Vergleichbarkeit mehrerer Studien gewährleistet         \item Entscheidungshilfen für gesundheitspolitische Fragen         \item Überblick über Forschungslage     \end{itemize}      \column{.45\textwidth} % Right column and width     \centering \textbf{Kontra}     \vspace{0.2cm}      \begin{itemize}              \item \enquote{Äpfel-Birnen Problem}         \item \enquote{Garbage in - garbage out}         \item \emph{Publication bias}            \end{itemize}  \end{columns}  \end{frame}  \end {document}   It looks like this. I think the problem is quite obvious. I would like to make the "Pro" and the "Kontra" as well as the items appear in one line    Thank you very much for your help.   Helena


$\lambda_{\max}\geq n$ for a positive reciprocal matrix

Prove that $\lambda_{\max}\geq n$ for a positive reciprocal ($a_{ij}=\frac{1}{a_{ji}}$ for all $i,j\in\{1,2,\dots,n\}$) square matrix $A$, where $n$ is the number of rows of $A$ and $\lambda_{\max}$ is its dominating eigenvalue. Also prove that $\lambda_{\max}=n$ if and only if $A$ is consistent ($a_{ij}a_{jk}=a_{ik}$ for all $1\leq i,j,k\leq n.$) If anyone knows the proof or can give a link to it, it would be very much appreciated as I cannot find it anywhere.


Can you trip as part of a Tome of Battle Maneuver?

If a ToB Maneuver such as Daunting Strike calls for a melee Attack as part of the maneuver, can this melee attack be resolved as a trip attack/include a trip attempt?


I'm trying to find out whether there is any kind of equivalent command line one-liner which replicates the exact identical functionality of the 'Lock Screen' menu option available via the Keychain app in OS X 10.6  I'm aware of the all the 'usual' solutions (sleep/screensaver preferences to require a password on reactivation) but these are not suitable to me.  I'm also aware of this option:  /System/Library/CoreServices/Menu\ Extras/user.menu/Contents/Resources/CGSession -suspend   which is also not suitable for me.  The perfect functionality is the 'Lock Screen' option however I have not yet found an elegant way to call it.  At the moment, I am calling via Automator, which isn't elegant!  I have read much about this issue and my understanding is that no-one has yet found the 'holy grail' but I was wondering whether that might have changed.


Making ffmpeg process first audio stream differently than all others

I'm trying to write a command such that ffmpeg executes a given instruction for the first audio stream in a file and a different instruction for any and all others.  In the test case below, for example, I want the first stream copied to the output file and all others converted to mono.  If I write it this way  ffmpeg -i INPUT -map 0 -c copy -map 0:a:0 -c:a:0 copy -map -0:a:0? -c:a libfdk_aac -ac 1 OUTPUT   the first audio stream is ignored when the mapping is overridden later in the command line.  But if I move the instruction for that stream to after the others'  ffmpeg -i INPUT -map 0 -c copy -map -0:a:0? -c:a libfdk_aac -ac 1 -map 0:a:0 -c:a:0 copy OUTPUT   it's no longer ignored, but becomes the last audio stream in the file.  I know I'm close here; I just can't see what I'm doing wrong.


How to remove monkey test and time service?

I am using a Micromax Canvas A116. It's not a rooted phone. I've done a factory-reset, but still malware app existing. How to remove monkey test, time service in mobile phone? And everytime phone gets reboot and unwanted apps like get touch, paytm etc., get installed. How to resolve this?    Screenshot (click to enlarge)  I tried all the possible ways


Two square matrices with the same minimial polynomial are similar for $n=5$ or $n=6$

Let $\mathbb{F}$ be a field, $\lambda \in \mathbb{F}$ and $A,B \in M_n(\mathbb{F})$ such that $m_A(x)=m_B(x)=(x-\lambda)^k$ and such that the geometric multiplicity of $\lambda$ in $A$ equals to the geometric multiplicity of $\lambda$ in $B$. a. Prove that for $n=5$ or $n=6$- $A$ and $B$ are similar b. Find an example for $n=7$ for which $A$ and $B$ are NOT similar    My main question here is whether I should try proving it for $n=5$ and $n=6$ seperately? Or should I try proving it for any $n$ and then observe that it holds only for $n=5$ or $n=6$? Plus, any hints or suggestion regarding my main question or the question above will be welcome


If each term $a_k$ is either 0 or 1, how many sequences are there $a_1, a_2, \cdots$ , $a_n$ such that    $$a_1 \leq a_2 \geq a_3 \leq a_4 \cdots?$$   If we let $f_n$ be the number of ways for a n-term sequence, we can get a recursive formula.   Suppose $a_1=1$. Then $a_2=1$ and $a_3=0,1$ which is actually $f_{n-2}$.  Suppose $a_1=0$. If $a_2=1$, we get $f_{n-2}$ by similar reasoning. If $a_2=0$, $a_3=0$ so the cycle repeats. Thus the # of ways in this case is $f_{n-2}+f_{n-4}+f_{n-6}+\cdots$.  So the recursive formula will be $$f_n=2f_{n-2}+f_{n-4}+f_{n-6}+\cdots$$ and $f_1=2, f_2=3$. How do I get a closed form, or did I find the wrong recursive relation?


When multiplying fractions by whole numbers, what is the correct way to write the operator?

I am currently working through an assignment and one of the parts of my solutions is to multiply $\frac{3}{64}$ by three. The assignment is much more complex than that, don't worry! But in thinking about how to write this in LaTeX, it inspired another question.  I've looked up previous questions and I have found two solutions - either $\frac{3}{64}\cdot3$ or $\frac{3}{64}\times3$ will do the job. However, the answers for these questions don't really go over why and when to use $\cdot$ and $\times$. In this case, what would the correct operator be? In addition - and more generally - where would each symbol be mostly used and why?


Finding an uncountable chain of subsets the integers

How to find an uncountable subset of $P(\mathbb{N})$ such that every two elements of it can be compared. In fact, give an uncountable subset of $P(\mathbb{N})$ such that has totality property. We mean by $P(\mathbb{N})$, the powerset of natural numbers set $\mathbb{N}$.


Is it acceptable to add a duplicate answer to several questions?

Let's say there is a user who has found a satisfactory answer to a common question asked on Stack Overflow (or other Stack Exchange website).  This answer may be a snippet of code, or an addon, or a framework, or something else.    Is it acceptable for this user to formulate an answer for one question, find every related question and then copy the exact answer to each of those questions?  And, if not, what should  users who finds themselves in this situation do?


How can a proton be converted to a neutron via positron emission and yet gain mass?

The mass of a neutron is greater than mass of a proton so how is it possible in positron emission for a proton to form a neutron and a positron?


Definition of complex conjugate in complex vector space

I am starting reading about Hodge theory and while reading the definition of abstract Hodge structure a very basic question came to my mind... What is the definition of the conjugate of a subspace of a complex vector space?  I found online the definition of conjugate of an entire vector space, but when we do the Hodge decompostition we want $V_{\mathbb{C}}=\oplus_{p,q \in \mathbb{Z}}V^{p,q}$ with the requirement $\overline{V^{q,p}}=V^{p,q}$. So I want to take a conjugate inside the space $V_{\mathbb{C}}$. I can see it if my space is of differential forms, but what is the definition for an abstract one?  Also, if I take the tensor product of two vector spaces, is this conjugation induced componentwise?  I know the question is pretty basic, but I couldn't find any reference for such definitions.


How do I write a mathematical equation for seasonal ARIMA (0,0,1) x (2,1,2) period 12

Can someone could help me write the mathematical/backshift equation for the seasonal ARIMA (0,0,1) x (2,1,2) with 12 periods? I'm confused with how to go about this. I would prefer an equation involving $B$, $Y_{t}$, $e_{t}$, $\phi$, $\Phi$, $\theta$, and $\Theta$.  This is different from other models that have previously been answered and I don’t understand the explanation in FPP2.


The connotation of adjective 'appropriate' is positive, while that of the verb is negative.   1. What's this phenomenon called, though this question allows any part of speech (and not just an adjective and verb, as above)? I ask this so that I can try to find lists of such words.   2. Why? Does the etymology depend on each word, or is there a more general theory?


The following minimal example no longer produces bold fonts in math mode, using either {\bf b} or \mathbf{b}. \documentclass{beamer}  \begin{document}  Text mode: {\bf b} $ = b$  \[ \text{Math mode with \texttt{bf}:}\quad {\bf b} = b \]  \[ \text{Math mode with \texttt{mathbf}:}\quad \mathbf{b} = b \]  \end{document}  I am using pdflatex on Ubuntu 20.04. The precise version is:  pdfTeX 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian) kpathsea version 6.3.1 Copyright 2019 Han The Thanh (pdfTeX) et al. There is NO warranty.  Redistribution of this software is covered by the terms of both the pdfTeX copyright and the Lesser GNU General Public License. For more information about these matters, see the file named COPYING and the pdfTeX source. Primary author of pdfTeX: Han The Thanh (pdfTeX) et al. Compiled with libpng 1.6.37; using libpng 1.6.37 Compiled with zlib 1.2.11; using zlib 1.2.11 Compiled with xpdf version 4.01   On a different computer, with TeX Live 2013, the pdf is created as intended, with bold fonts also in math mode. Below the output of TeX Live 2013 and TeX Live 2019 side by side.  The following error is reported in the .log file when using TeX Live 2019:  LaTeX Font Warning: Font shape `OT1/cmss/b/n' undefined (Font)     using `OT1/cmss/m/n' instead on input line 8.  The same error does not occur when using the older installation.


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I'm having difficulty listing my comments on Stack Exchange Data Explorer. I'm not experienced with it. I tried this query, and it didn't list anything. 42672 is my id on SuperUser. SELECT   Id AS [Comment Link],   Text FROM Comments where UserId=42672


How can I have my terminal start with an ASCII banner?

How can I have my terminal in Ubuntu start with an ASCII banner every time from default?


I currently have Centos 7 installed on EC2 with the following: Apache Php Mysql Iptables Firewalld    Apache running     Redirecting to /bin/systemctl status  httpd.service ● httpd.service -   The Apache HTTP Server    Loaded: loaded   (/usr/lib/systemd/system/httpd.service; enabled; vendor preset:   disabled)    Active: active (running) since di 2016-01-26 01:18:52   UTC; 16min ago        Docs: man:httpd(8)              man:apachectl(8)   Process: 4387 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)  Main PID: 4392 (httpd)   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:    0 B/sec"    CGroup: /system.slice/httpd.service              ├─4392 /usr/sbin/httpd -DFOREGROUND              ├─4393 /usr/sbin/httpd -DFOREGROUND              ├─4394 /usr/sbin/httpd -DFOREGROUND              ├─4395 /usr/sbin/httpd -DFOREGROUND              ├─4396 /usr/sbin/httpd -DFOREGROUND              └─4397 /usr/sbin/httpd -DFOREGROUND   FIREWALLD Disabled:     ● firewalld.service - firewalld - dynamic firewall daemon    Loaded:   loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor   preset: enabled)    Active: inactive (dead)   IPTABLES ENABLED     ● iptables.service - IPv4 firewall with iptables    Loaded: loaded   (/usr/lib/systemd/system/iptables.service; enabled; vendor preset:   disabled)    Active: active (exited) since di 2016-01-26 01:14:23 UTC;   2min 27s ago   Process: 4317   ExecStart=/usr/libexec/iptables/iptables.init start (code=exited,   status=0/SUCCESS)  Main PID: 4317 (code=exited, status=0/SUCCESS)   IPTABLES RULES     Chain INPUT (policy ACCEPT) target     prot opt source   destination   ACCEPT     all  --  0.0.0.0/0     0.0.0.0/0            state   RELATED,ESTABLISHED       ACCEPT     tcp  --   0.0.0.0/0            0.0.0.0/0            tcp dpt:80       ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp   dpt:22       ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0      Chain FORWARD (policy ACCEPT) target     prot opt source   destination               Chain OUTPUT (policy ACCEPT) target     prot opt source   destination   Iptables sysconfig file:     *filter       :INPUT ACCEPT [0:0]       :FORWARD ACCEPT [0:0]       :OUTPUT ACCEPT [214:43782]      -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT      -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT      -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT      -A INPUT -i lo -j ACCEPT COMMIT   Selinux:     getenforce: Disabled   My virtualhosts are correct, pass the configtest and all.. So with these settings, I still receive nothing on my webserver. Nothing in my access logs or error logs.. What I am overseeing in my configuration?  Thanks in advance.


What happens if the empty set is not a subset of every set?

$\hskip8pt$ Definition. If $A$ and $B$ are sets, then $A$ is a subset of $B$ iff every element of $A$ is also an element of $B$.  The empty set $\{\}$ is a subset of every set because, if $A$ is an arbitrary set, then every element of $\{\}$ is also an element of $A$. This statement is said to be "vacuously true" because $\{\}$ has no elements.  But what about statements that imply the negation of this?  Namely: the empty set $\{\}$ is not a subset of any set because, if $A$ is an arbitrary set, then not every element of $\{\}$ is an element of $A$. Couldn't this statement be vacuously true because $\{\}$ has no elements?  What about: the empty set $\{\}$ is not a subset of some sets because there exists a set $A$ with the property that not every element of $\{\}$ is an element of $A$. Couldn't this statement be vacuously true because $\{\}$ has no elements?  I understand that the fact that the empty set is a subset of every set (by vacuous truth) is merely a convention (I might be wrong, and it might be a necessity, to avoid contradictions or something). Is it possible to develop a (contradiction-free) mathematical formalism where we adopt the opposite convention? If so, what are the consequences?


Set footer to the bottom in Single page application

I am trying to create a Single page application.  html content:

   All my application content will go inside contentDiv along with ng-view.  css content:  .containerDiv { position: relative; min-height: 100%; background-color: beige; }  .headerDiv { height: 60px; background: black; width: 100%; }  .contentDiv { padding-bottom: 60px; }  .footerDiv { position: absolute; left: 0; bottom: 0; right: 0; background-color: pink; width: 100%; height: 60px; }   Everything works fine with non-positioned elements and footer stay at the bottom, when content height increases.  I want to add positioned elements(absolute or relative) in the contentDiv as per my requirements.  When height of my positioned element increases, it breaks my page as footer remains at same position and elements overrides it.  Suppose I want to add a table in contentDiv

   I want to align table at particular location in html.  .data{  position:absolute/relative;  top: 300px;  left: 400px; }   If height of the table increases, it will go out of the scope of footer. The height of the table is dynamic.


How to kill a player when they touch a block?

I am making a multiplayer parkour map on bedrock edition, and I have it set up where when a player steps on a grass block they die. But when a player steps on a grass block it just kills anyone who touches it.  First: A repeat command block (set to always active and unconditional)   execute @e [type=player] ~ ~ ~ testforblock ~ ~-1 ~ grass   And then I have a chain command block (set to conditional and always active)  kill @e [type=player]   And it does work..... IF in singleplayer only. (which is not at all what I want)  Thank y'all in advance.


I need to add a new directory to my PATH so that SublimeText can find it. I assume this should be added to either .bash_profile, .bashrc, or .profile.   Which one should I add it to?   .bash_profile already has:   export PATH="/home/josh/.rvm/gems/ruby-2.1.5/bin:/home/josh/.rvm/gems/ruby-2.2.0/bin:/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:$PATH"   in it.  .bashrc and .profile both have:  export PATH="$PATH:$HOME/.rvm/bin"   in them.   Should I have all of these in just one of the files and do multiple 'export' statements just get chained together when processed, even if from different files?


It is a general question on linear regression with polynomial terms. I am using x and x^2 as my independent variables and my regression equation is as follows y=a0+a1*x+a2*x^2+a3*z+e. I am doing regression to find the coefficients. I have read through  article, which explains that I need to de-mean the variable x before I run the regression to obtain my coefficients a1 and a2. Once we de-mean our new variables (de-meaned and its square) are not correlated.  I was wondering is it necessary to always de-mean the variables when we use the polynomial term as well?  EDIT: Clarifying further - when i am using the linear and quadratic terms both. Do I need to de-mean the linear term (call it demean_x) and take the square of it (demean-x^2) and use them for regression instead of x and x^2.


I have OpenSuse 15.1 "Magic Leap" installed.  I noticed that there seems to be two conflicting commands named ss.  When I run which ss, I get this:     /usr/sbin/ss   And when I try to inspect, notice this...  >* whatis ss ss (8)               - another utility to investigate sockets   Which to me looks like the iproute2 command I expect - a modern replacement to netstat and the like. However, attempts to use this said command to for example list all active tcp connections on the machine show that the command in my default namespace is different!    See what happens with ss -t  >* ss -t su: invalid option -- 't' Try 'su --help' for more information.   Which to me looks like ss is now an alias for su, the super user util.   So, is this an OpenSuse "feature", bug or what?   Also, invoking the command from an unprivileged shell automatically summons sudo and leaves me on a root shell - further hinting at the later possibility!  I don't wish to install a deprecated netstat if there's a new, modern way to do things, but then, how do I get to the proper ss command?      UPDATE:   As per muru's suggestion, here's the output of type -a  >* type -a ss ss is aliased to `sudo su' ss is /usr/sbin/ss ss is /usr/bin/ss   Further, upon inspection with file, I find that these two "versions" of ss reported above, actually are the same. See the following...  >* file /usr/bin/ss /usr/bin/ss: symbolic link to ../sbin/ss >* file /usr/sbin/ss /usr/sbin/ss: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/l, for GNU/Linux 3.2.0, BuildID[sha1]=4cb972d442c793ac1783b508f94e7aaceaf83088, stripped >* /usr/sbin/ss --version ss utility, iproute2-ss170705   So, at the same time, ss seems to be an alias for sudo su, yet upon inspection, seems to be the iproute2 command. Weird.


Python error with OpenLayers plugin QGIS 2

I've been using QGIS for a while but since using QGIS 2 the OpenLayers plugin doesn't work for me on my home PC. However, I have installed the same version at my workplace with success. I have looked through other posts, and tried setting the CRS and allowing on the fly but it doesn't work for me.  Can anyone offer any other guidance?   I have also tried uninstall/ re-install.  Error code below:     An error has occurred while executing Python code:      Traceback (most recent call last):     File "C:\Users\Lee/.qgis2/python/plugins\openlayers_plugin\openlayers_plugin.py", line 48, in addLayer       self.plugin.addLayer(self)     File "C:\Users\Lee/.qgis2/python/plugins\openlayers_plugin\openlayers_plugin.py", line 194, in addLayer       layer = OpenlayersLayer(self.iface, self.__coordRSGoogle, self.olLayerTypeRegistry)     File "C:\Users\Lee/.qgis2/python/plugins\openlayers_plugin\openlayers_layer.py", line 64, in __init       self.page = OLWebPage()     File "C:\Users\Lee/.qgis2/python/plugins\openlayers_plugin\openlayers_layer.py", line 38, in init       proxy = getProxy()     File "C:\Users\Lee/.qgis2/python/plugins\openlayers_plugin\tools_network.py", line 42, in getProxy       proxy.setPort(settings.value("/proxyPort", 10, type=int))   TypeError: unable to convert a QVariant of type 10 to a QMetaType of type 2      Python version:   2.7.5 (default, May 15 2013, 22:44:16) [MSC v.1500 64 bit (AMD64)]      QGIS version:   2.0.1-Dufour Dufour, d94c044      Python path: ['C:/PROGRA~1/QGISDU~1/apps/qgis/./python/plugins\processing', 'C:\Users\Lee\.qgis2\python\plugins\GeoCoding', 'C:/PROGRA~1/QGISDU~1/apps/qgis/./python', 'C:\Users\Lee/.qgis2/python', 'C:\Users\Lee/.qgis2/python/plugins', 'C:/PROGRA~1/QGISDU~1/apps/qgis/./python/plugins', 'C:\PROGRA~1\QGISDU~1\bin\python27.zip', 'C:\PROGRA~1\QGISDU~1\apps\Python27\DLLs', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\plat-win', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\lib-tk', 'C:\PROGRA~1\QGISDU~1\bin', 'C:\PROGRA~1\QGISDU~1\apps\Python27', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\PIL', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\win32', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\win32\lib', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\Pythonwin', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\Shapely-1.2.18-py2.7-win-amd64.egg', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\six-1.3.0-py2.7.egg', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\wx-2.8-msw-unicode', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\xlrd-0.9.2-py2.7.egg', 'C:\PROGRA~1\QGISDU~1\apps\Python27\lib\site-packages\xlwt-0.7.5-py2.7.egg', 'C:\Users\Lee\.qgis2\python\plugins\mmqgis/forms', 'C:\PROGRA~1\QGISDU~1\apps\qgis\python\plugins\fTools\tools']


With a phone of 1 GB internal memory, I am able to install apps for 700 MB only. More than that I get the insufficient memory alert.   Storage shows:   Total space 0.98  Available 71.49 Apps 601 Cache 1.88   Another phone of the same model is able to able to install apps for the entire 1GB.  Phone runs on Android version 4.2.x. Default write disk is external SD card.   Thanks in advance. Screenshots below:    Screenshots: My phone, other phone (click images for larger variants)


Maximum current on gpio header pins (not on device)

I have a lot of low current devices in need of 5V or 12V power. So far I have been using cable connectors like this:  The problem is that by "a lot" I am talking about 15-20 devices consuming only a few milliamperes. As you can imagine this is starting to take a lot (too much) space when using those cable connectors. I am now planning to use an empty PCB breakout like this:  and solder a GPIO header onto it. Then I am going to solder all the pins of the GPIO header together using a thick naked copper strand thus providing me a lot of connection points to take power from. Now my question is, what are those GPIO headers normally rated for? The pin pair that I will be using to supply the power/ground will ultimately have to handle the sum of all devices. The power source is not intended to supply much more than 3A and has built-in overcurrent protection that should trigger at around 3.3A. Since the raspberry pi can also be powered from the GPIO 5V pin which is using the same type of connector I am assuming 3A should probably not exceed the rating, however "assuming" is never good. I was not really successful in finding anything official for those headers since whatever I am searching just shows information about either arduino or r-pi ratings. Maybe important: I am not using the typical GPIO 26 AWG cables to supply the power, its 18 AWG cables. Just for completeness what I mean by GPIO header:


How to drop certain values for a factor variable while fitting a GLM?

My response var is a binary variable. In the predictor variable i have a type variable with levels as l1,l2,l3,l4. And when i run a logit (glm(redonse ~ type, family = "binomial"), Some levels of type variable turn out to be insignificant. i.e typel2 comes out to be insignificant. So my question is that, could i drop a that level for a variable somehow. ie i drop typel2 (treat typel2 as NULL or so)and then run the glm. i hope the question is clear.


Is there a faster alternative to dict(zip(list1,list2)) in python3?

Need to find a faster alternative to python's dict(zip(list1,list2))  I'm using dict(zip(list1,list2)) in a script for random forest classification which creates a dictionary from two lists. This takes about 0.002 seconds per execution. However its too slow for bulk prediction(when it needs to be executed 80K+ times)  for inp in listOfInputs[:]:     pp = clf.predict_proba(inp)[0]  # clf is the classifier     probaDict = dict(zip(clf.classes_,pp))   This loop takes 0.6 seconds if len(listOfInputs)=290 which is slow. I need an efficient alternative for use with large bulk inputs for which  len(listOfInputs)=80,000+


Such questions are inevitable. Technology makes guns, and questions on how to use them follow. How do I shoot [targets] [birds] [other people] [my own foot]?  It's no surprise that we all see "how do I do the inadvisable" on many different subjects on the many variations of Stack Exchange. So how should you respond to someone asking how to shoot themselves in the foot?  Most/all of us immediately want to find out why the OP is asking. This is mainly prudence guarding against accidents. But it isn't always possible for an OP to answer that question of "why". They've spent days analyzing it and the logic that led them to ask this question isn't simple to explain without pages of work. Or more commonly they're a little unclear themselves, and are unable to explain why they want something, just that they really really want it and could someone tell them how please.  I've seen multiple ways of responding such questions, including but not exclusively:   Ignore the question. Move on and let the tumble weed deal with the OP. There's no shame in it. Assuming the OP has an XY problem and answering an entirely different question the OP didn't ask. This frequently frustrates the OP as they've put some thought into the fact that shooting themselves in the foot really is what that want. Endless lectures on the dangers of guns, both in comments and answers.  Also frustrating to the OP. See above. Down voting the question.  Even though the question is clear, well formed and posted on the right site for the subject. If one person has asked how to do it, then chances are that another will want to as well. Simply giving the answer to their question explaining how to load, aim and pull the trigger. I mildly prefer this but it does lead to concerns that future readers will fail to realize that an ambulance and hospital will be required.   These are merely my observations of what others do. I was wondering if the community has any ideas of best practice:   How do we satisfy the OP and protect future readers? Do we need to do both these things? Should such questions be worthy of down voting? Is it better to leave such questions unanswered, even if the technical answer is simple enough to give?


How to use awk to find and replace with calculation?

I have several CSS files under a folder contains 0.2rem or 0.5rem 0.6rem, now I want them to be all divided by 2, become 0.1rem and 0.25rem, 0.3rem. How can I use awk or sed or gawk to accomplish this?  I tried the following command but have no success:  find . -name "*.css" | xargs gawk -i inplace '{gsub(/([0-9\.]+)rem/, "(\\1 * 0.5)rem"); print $0}'


How to split string and push in array using jquery

var string = 'a,b,c,d'; var array = [];   As we can see above I have one string values with separator*(,)*. I want to split these values and wants to push in the array. At last I want to read my array by using for loop. Please suggest.


How to change the Fieldname(s) in the attribute table

I joined some data from excel to arcmap, but the added fieldnames from the excel table (land, Germany, field3, field4, ...) aren't the fieldnames which I want to use. For example land=district and Germany has to be 2006. When I only change the alias name, the name removes when I turn my PC off... Is there a way to change them permanently.  I found out that the data was visable at the attribute table, but it was not at the fields in the shapefile properties. By exporting the joined shapefile to a new shapefile this problem is fixed, but the fieldname(s) are still not editable.   I saw you can edit the names at the shapefile properties, but when I change them it gives a "Alter field name Failed" error.  Does somebody know a solution?


Using Python from both OSGeo4W and ArcGIS Desktop?

This question was asked several years ago at: , but it seems that versions have changed since then.  I currently have ArcGIS 10.0 installed (not sure when I will upgrade to 10.1) and I would like to install OSGeo4W on my computer as well.  ArcGIS 10.0 installs Python 2.6.5 and OSGeo4W wants to install Python 2.7.2.  Can these two packages use the same Python installation despite different versions?  Otherwise, is there an easy way to install OSGeo4W with the correct Python version and keep the two Python versions completely separate on a single computer?


What happens when post older than 60 days scored +3 or higher is deleted by 6 "No Comment" recommendations?

As far as I understand, it is possible for post scored +3 or higher to land in Low Quality queue and be deleted by 6 "No Comment" recommendations.  Besides a , what happens in this case? As far as I understand,   moderators can't find about this since system doesn't raise a flag for their attention authors can't find it out since there's neither , nor  that could be visible in profile, nor is it listed in  in their profile deleted post is added to the list of recently deleted in  page   Is my understanding correct? Is there something worth worrying about in this process?    For the sake of completeness, same seems to be happening to old posts without votes at all, or those having zero reputation "balance" due to up/down votes split. I don't ask about these because I don't even know whether there is a reason to worry about deletion of higher voted posts.


Given a series of numbers, generate new numbers that are "similar" to the original numbers

I'm a programmer but I don't know much about stats, so please excuse me if this question sounds naive.  I have two computers that are in different locations.  I have made N measurements for the network distance between them.  So it's essentially a series of N numbers like 200ms, 173ms, 212ms....  Now, I need to write a simulator that simulates these two computers.  What I need is a generator that can generate new network distances between them.  So for instance, if the generator generates something like 183ms, then it'd be reasonable.  But if it generates, say, 1 billion ms, then that wouldn't make sense since it deviates so much from the original data set.  So how would I generate new numbers that are similar to the numbers in the original series?  P.S. I'm not sure what tags I should use for this question because I don't know much about stats... feel free to add tags that you think are more appropriate.


Just started to learn vector, but I got this error from VC++2010 and stuck there, help please....  "error C2228: left of '.push_back' must have class/struct/union"  #include <vector> #include <iostream> #include <limits>  using namespace std;  int main() {     vector<double> myVector();     double temp = 30.0;     myVector.push_back(temp);   //this line makes error ?? why??      return 0; }


My question is may seem vague to some, but for me is a concept I am now learning for the first time (Tensors). I'm now reading from "APPLICATIONS OF CLASSICAL PHYSICS" by Roger D. Blandford and Kip S. Thorne. There in Ch.1 they introduce a the notion of a tensor being a "thing" that accepts vectors as inputs and gives out numbers or more specifically a real value. So the detailed version of my question is, if someone can think of Tensors as operators acting on multiple vectors at once. Or are vectors a special kind of operators? I know that scalars and vectors can be thought as operators. But scalars and vectors can also be thought as tensors. Does the concept of tensors incorporate operators or the other way around? Or am I losing the point entirely


Do we have to use starred equations with \tag?

Consider the following MWE: \documentclass{amsart} \usepackage{hyperref} \begin{document} \begin{equation}     \tag{tag}     1+1=0 \end{equation} \clearpage \begin{equation}     \label{mylabel}     1+1=3 \end{equation} Eq~\eqref{mylabel} is on page \pageref{mylabel}. \end{document}  If I compile it with pdflatex, the \pageref correctly says that the equation (1) is on page 2, however the hyperref points to page 1. If we change the first equation to equation*, the hyperref points correctly to page 2. Note that this change does not alter the aux-file, but in the log-file the warning pdfTeX warning (ext4): destination with the same identifier (name{equation.0.1}) has been already used, duplicate ignored  disappears. Hence, my question is: Should one always use starred environments (like equation*) for \tagged equations? (I cannot find something related in the documentations of amsmath and hyperref.)


What should raise red flags to detect fabricated data

In academia, there has been recently some cases that came to light of very well known scientists that have fabricated their data out of thin air.  In some instances these papers have been cited many times by other researchers and some of them have even been praised. Thus, when the truth came to light, it also appears to the  public that scientists have bad peer-review processes.  In light of the presented reasons, how can a reviewer make at least some sanity test that the data is (most likely) not fabricated? Suggesting so could come as a great injury to the researcher, but I think there should be some kind of mechanism to control this.


How to solve given Recurrence Equation $a_{n} = 6n^2 + 2n + a_{n - 1}$?

How to solve given Recurrence Equation $a_n = 6n^2 + 2n + a_{n - 1}$ ?  Given $a_{1} = 8$  Find the value of $a_{99}$ ?    Is there any procedure or approach for such questions ?


I would like to recognize a good answer giving away some points to the guy who answered. In this case I did a dumb and incorrect question and the guy foreseen why my question was incorrect and corrected it (curious guys ), but I already did this before some times. Correct me if I'm wrong, but I think that this is a somewhat common practice.  The thing is that waiting for the bounty time and then one extra day to reward the answer takes... time. I know that the bounty time is to avoid giving bounty hastily, but many times the answer for a well-defined question is correct or wrong, no middle way.   Plus, when using bounty hunter the way I'm doing, I don't want my question to have any extra attention. I just want to reward a guy.  What about open the possibility to give away some extra bounty instantly for the accepted answer? Or even better, add a "reward" option, since it is semantically different from a bounty?  Note that it has it value to SO too - I'm actually telling, judging by that answer, that this guy is X * 2 points more reliable then myself.


A good substitution to prove $\frac{f(b)-f(a)-(b-a)f'(a)}{g(b)-g(a)-(b-a)g'(a)}=\frac{f''(c)}{g''(c)}$.

Let $f'(x)$ and $g'(x)$ satisfy the hypothesis of mean value theorem, then prove that     $$\frac{f(b)-f(a)-(b-a)f'(a)}{g(b)-g(a)-(b-a)g'(a)}=\frac{f''(c)}{g''(c)}$$   where $g''(c)\neq 0$. I have tried various things like Cauchy MVT with $f'(x)$ and $g'(x)$, substituting $h(x)=\dfrac{1}{g'(x)}$ ,$h(x)=f'(x)+\dfrac{a}{g'(x)}$ where $a\in\mathbb{R}$, but it didn't lead anywhere. Any help will be appreciated. Please note that I am allowed to use only Cauchy's MVT, LMVT and Rolle's theorem.


My overall upgrade went well, but I am left with a critically lingering issue of mysql-server not being able to install itself, and nothing I am trying gets it to work.  This is the error I see when trying to install/reinstall it:  Setting up mysql-server-5.7 (5.7.11-0ubuntu6) ... Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details. invoke-rc.d: initscript mysql, action "start" failed. dpkg: error processing package mysql-server-5.7 (--configure):  subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of mysql-server:  mysql-server depends on mysql-server-5.7; however:   Package mysql-server-5.7 is not configured yet.  dpkg: error processing package mysql-server (--configure):  dependency problems - leaving unconfigured No apport report written because the error message indicates its a followup error from a previous failure.                    Processing triggers for systemd (229-4ubuntu4) ... Processing triggers for ureadahead (0.100.0-19) ... Errors were encountered while processing:  mysql-server-5.7  mysql-server E: Sub-process /usr/bin/dpkg returned an error code (1)   I've tried completely removing it, though doing so attempts to install MariaDB because of dependencies (?). Any suggestions on what I can do to fix this would be most welcome.  EDIT: Looks like I'm not the only one:


Whenever I click on software updater it says Failed to download repository information.  It's been saying this for the past few days now and I don't know why, my Internet connection is fine, I am able to manually download software.  Sometimes it crashes when I click okay, then attempts to look for updates again and gives me the same message.  Any ideas?  [EDIT] I just tried an answer posted where I reset where the downloads come from, but I was left with this message:  W:The repository 'http://ppa.launchpad.net/noobslab/noobslab-conky/ubuntu xenial Release' does not have a Release file.,  W:Data from such a repository can't be authenticated and is therefore potentially dangerous to use.,  W:See apt-secure(8) manpage for repository creation and user configuration details.,  W:https://content.runescape.com/downloads/ubuntu/dists/trusty/InRelease: Signature by key AAC9264309E4D717441DB9527373B12CE03BEB4B uses weak digest algorithm (SHA1),  E:Failed to fetch http://ppa.launchpad.net/noobslab/noobslab-conky/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not Found,  E:Some index files failed to download. They have been ignored, or old ones used instead.


Understanding Negative feedback loop circuit with an Ideal Op-Amp

The following is given as an example of a negative feedback loop in my textbook, note that the op amp is assumed to be ideal.  However I do not seem to get the logic behind this acting as a negative feedback loop, suppose if \$V_{in}\$ is \$0.01 \$ after passing through the op amp it should be amplified to \$+6\ \mathrm V\$. Now \$V_{out}\$ is \$+6\ \mathrm V\$ hence the inverting input will also become \$+6\ \mathrm V\$ thus the difference between the two inputs becomes \$-5.99\ \mathrm V\$ thus \$V_{out}= -6\ \mathrm V\$ and this process shall repeat over and over again, would the circuit then just cycle between being \$+6\ \mathrm  V\$ and \$-6\ \mathrm V\$ until the power supply is disconnected? How is this considered a negative feedback, am I missing something crucial?


In the RSASSA-PKCS-v1_5 signature scheme, the first step is to perform an encoding on the hashed data. (0x00||0x01||PS||0x00||T). Is this encoding important for security ? What happens if the hash is directly encrypted without encoding ?


UnitTesting Fundamentals - What exactly to test?

I know that Unit Testing is all about testing individual units of code and mocking the other dependencies like database connections, file I/O etc.  I have a few questions on unit tests   what is that "UNIT" in unit testing that we need to test? Is it a method of a class? or a use-case? Because use-case testing seems more of an integration test to me. Mocking external dependencies. Does it mean to mock all references to any external class even if it is same package?


Can not send email by smtp using G Suit account.

This question might be flagged as a duplicate But it is not. Because the code sends email successfully  when using normal gmail account that ends with @gmail.com. The problem only happens when using G suit accounts that are custom and ends with @yourdomainname.com.   I am using this code to send email. My account has two-step verification so I created an app password for verification and use it to send email.   using (var mm = new MailMessage(PrivateSettings.SenderEmail, message.Destination))         {             mm.Subject = message.Subject;             mm.Body = message.Body;             mm.IsBodyHtml = true;             var smtp = new SmtpClient             {                 Host = "smtp.gmail.com",                 EnableSsl = true             };             var networkCred = new NetworkCredential(PrivateSettings.SenderEmail, PrivateSettings.EmailPassword);             smtp.UseDefaultCredentials = true;             smtp.Credentials = networkCred;                             smtp.Port = 587;                             smtp.Send(mm);                }   The above code sends email successfully  when I use my normal gmail account which is se.natnael.zeleke@gmail.com.   But when I use one of my G Suit account , connect@tatarri.com , to send email it fails and shows this error message.     So my question is; is their additional configuration that should be done for G suit gmail accounts.  Additional Info.  I configured both email accounts to use app password. connect@tatarri.com is also registered as admin in my G suit account.   Both email accounts have their IMAP enabled in settings.  I bought tatarri.com domain name from namecheap.  Thank you.


VUE JS: If I had a string such as "8^3", how would I store 8 and 3 as two separate variables?

I'm creating a calculator using VUE JS. I was wondering how to do exponents in that if I had something like "8^3", how would I split the string into the two separate digits?


I plan to self-study linear algebra this summer. I am sorta already familiar with vectors, vector spaces and subspaces and I am really interested in everything about matrices (diagonalization, ...), linear maps and their matrix representation and eigenvectors and eigenvalues. I am looking for a book that handles every of the aforementioned topics in details. I also want to build a solid basis of the mathematical way of thinking to get ready to an exciting abstract algebra next semester, so my main aim is to work on proofs for somehow hard problems. I got Lang's "Intro. to Linear Algebra" and it is too easy, superficial.  Can you advise me a good book for all of the above? Please take into consideration that it is for self-study, so that it' gotta work on its own. Thanks.


Emphasized Wrinkles, Freckles, and Dark Spots

Is there a name in photography postprocessing for this kind of look?      How can it be achieved?  There are other photos of this sort, but I can't find them right now.


I installed Ubuntu 12.04 LTS in Windows 8.1 using vmware workstation. When I open a file in the terminal using vi filename.c, the arrow buttons will not work properly, pressing up arrow prints A, down arrow B, right arrow C,left arrow D. How can I overcome this problem?


Recently learnt that Intensity= nhv ; where n is the number of photos per unit area My textbook specifies that the photoelectric current only depends upon the number of photons striking per unit time and area. So, why is that photoelectric current remains constant when frequency is changed keeping the Intensity constant? ie- if intensity is kept constant and frequency is doubled , shouldn't the photoelectric current become half the value?  Edit: I understand how frequency affects intensity ,just want to know what exactly  controls photoelectric current; intensity or number of electrons.


12.04 LTS with Windows 7 dual booted.  I installed Ubuntu from windows 7 via WUBI so that I can dual boot both.  When I try to boot Ubuntu the grub menu appears and I am not able to boot Ubuntu  I have some important data stored in it.  grub menu displays this message   GNU GRUB version 1.99.21ubuntu 3.14 minimal BASH-like line editing is supported for the first word ,TAB lists possible command completion, Anywhere else RAB lists possible device or file complete.


I want to cleanup my home folder and have managed to move out most of the configuration files to the .config folder. But, one file I'm not able to figure out is the .bashrc file. How can I specify bash to load .bashrc from a custom location?


Looking For A Physics Textbook That's not Super Complicated

I'm looking to be able to digest and comprehend some basic fundamental concepts, so that I may apply them in my hobby of electronics.   I got a copy of "Fundamentals Of Physics" by Halliday & Resnick. The teaching style is pretty bland,lacking very little detail, and most concerning is the fact that right out the gate your comprehension of concepts is tested by over the top questions, basically the level of complexity excels to quickly.  I have self-studied out of books that get real complicated, but its after proper instruction, and your not that worried about anything when you get there cause you know you have digested all the prerequisite subjects well.   Im looking for a high-school level physics book like that, it gets complicated, but it's very instructional and progressive. Does anyone know of any good physics books that fit the description?


I'm not really that familiar with AC, I've just started talking about it in my classes. But from what I understand, one of its formulations is that it is possible to create a set made from choosing elements from a series (potentially infinite) of other sets.  Are we doing this in the Diagonal argument? We have a countably infinite number of sets (each with a real number) and we create a different one by choosing a digit from each of the subsets.  Is this correct? Or am I misunderstanding AC, making some other error?  EDIT: It seems that someone asked which axioms of ZF did the argument use and it got answered. My question then becomes: Why doesn't Cantor's Diagonal argument depend on the Axiom of Choice?


Prove that $\sum_{j = 0}^p {p \choose j}{p + j \choose j} \equiv 2^p + 1 ~(\text{mod}~p^2)$

Let $p$ be an odd prime. Prove that $$\sum_{j = 0}^p {p \choose j}{p + j \choose j} \equiv 2^p + 1 ~(\text{mod}~p^2)$$  I have tried to write the problem as $$\sum_{j = 0}^p {p \choose j}{p + j \choose j} - 2^p - 1  \equiv 0~(\text{mod}~p^2)$$ Which mean I have to prove that the expression on the left side is divisible by $p^2$, but this doesn't help.  I also know that since $p$ is odd prime, we have $2^{\varphi(p^2)} = 2^{p^2 - p} \equiv 1 ~(\text{mod} ~p^2)$ by Euler's theorem. So the expression before can be rewritten as $$\sum_{j = 0}^p {p \choose j}{p + j \choose j} - 2^p - 2^{p^2 - p} \equiv 0~(\text{mod}~p^2)$$ But this also doesn't seem to help. I think I have to modify the sum somehow, but I gut stuck. The sum looks like a hypergeometric function, but knowing this doesn't help either.  Anyone?


The expression $\,\mathbf F_\mathrm G\boldsymbol{=}m\, \mathbf G\,$ and $\,\mathbf F_\mathrm E\boldsymbol{=}q\, \mathbf E\,$ make sense, but is there any derivation for $\,\mathbf F_\mathrm B\boldsymbol{=}q\,\left(\mathbf v\boldsymbol{\times}\mathbf B\right)$?


Minimum Processor Requirements: 12.04 vs 14.04 vs 16.04

I've searched around; found the minimum processor requirements for Ubuntu 16.04 in an offical format. I can't find offical guidelines for 12.04 and 14.04 ... just various people giving their opinions.  Does anyone know the URL(s) for where Ubuntu bury this information? - I have an old 32-bit machine with a T1350 processor (not even dual-core) running at 1.8GHz - It's running Windows 10 slowly with it's maximum 4gb of installed RAM. - I have Lubuntu downloaded ... - I'm just thinking that Ubuntu may give me a better experience than Lubuntu ... but which to choose ...   Thanks folks.  Regards, T


what are Mixins in the React.js framework?

I am reading Reactjs documentation and came across mixins,but i dont understand mixins clearly.What are mixins and what are they used for?


What is the purpose of the default keyword in this scene

I saw a question, which looks like this:  public @interface Controller {  /**  * The value may indicate a suggestion for a logical component name,  * to be turned into a Spring bean in case of an autodetected component.  * @return the suggested component name, if any  */ String value() default "";   }  What is the default keyword, and the "" after default?


What are the differences between "sudo -s" and "su root"? As they both can provide root permission.


I have two different servers(A1, B1) with mysql-5.1.73 and currently, I'm replicating DBs with another two servers(A2, B2).   I would like to know is it possible to do a centralized DB replication, which means replicating DBs of both Master_A1 and Master_B1 to a single Slave_A2.  P.S: database and their table names will be same in both Master servers.


For the purpose of Windows 10 reset, what are considered apps?

Windows 10 has an option to do a PC reset that keeps your personal files, but uninstalls any apps and drivers you have installed.  What are considered personal files and what are considered apps for this? For example, I got 600 GB of games installed, are these considered apps or personal files? Is my dropbox desktop client considered an app or a personal file? Are apps just the ones you install through the Windows 10 store, or also any other apps you may have installed?


Conservation of momentum and energy in an explosion

One simple problem is physics is to determine the mechanical energy difference after an explosion. To do this, you must assume that momentum is conserved because in a explosion you have internal forces, so, using Newton's third law, you get that the total momentum is conserved.  How true is that? I mean, when a explosion happens you have LIGHT and SOUND being propagated. And they carry energy and momentum. It's clear to me that if you only consider the momentum of the parts of the body + the momentum of the sound wave + the momentum of the light wave this should be equal to zero. However, it's not so clear if the momentum of the body should be equal of the sum of the momentum of its fragments. I have some conjectures, but I didn't find nothing related to that: I) The waves propagate symmetrically, so, because momentum is a vector, it should be zero. However, the explosion may not be total symmetric, so I don't know if this argument is valid. II) The momentum is not conserved for the body, but the momentum of the wave is negligible.   These are the two possibilities I considered, so I don't know if they are valid.


AMP Script Marketng Cloud EncryptSymmetric

I would like to encrpt a emailaddress with AES and decrypt  with a other java appclication. I try   %%[SET @encData=EncryptSymmetric(emailaddr, "AES;mode=cbc;padding=pkcs7", @null, "1111222233334444", @null, "0000000000000000", @null, "00000000000000000000000000000000") ]%%   this works for encryption, but the can't decrypt this email. I have try  a lot of implementations : I got errors like this:  javax.crypto.BadPaddingException: pad block corrupted  my initVector is in my javaclass :   byte[] initialVector   =new  byte[] { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };   It's 16 bytes long, but in the AMPScript function 32 chars?  What is my problem?


What is the advantage of using kosher salt

I have seen a number of recipes that call for using "kosher salt". This is ridiculous to me, as I very well know that all salt is kosher, and so I am wondering what I am missing here. What is the advantage (and uses) of kosher salt as opposed to ordinary table salt?


How may I find out how to bring a terminal up?

I am a brand new user of Ubuntu and cannot figure out how to get to a terminal. What do I need to know?


Does there exist some strictly positive function such that both the derivative and second derivative are strictly negative?

If $f(x) > 0$ over the reals is it possible to have $f'(x) < 0$ and $f''(x)< 0 $ over the reals? Assuming $f$ can be differentiated twice.


If a manifold M has zero Euler characteristic, there is a non-vanishing vector field on it

There is hint: if M has isolated singular points, find a diffeomorphism to make these singular points in a any neighborhood which you want. How can we do next?


Cartoon Network show with three main characters who battle with cards

I have been searching for ages and ages. But can’t find anything, so does anyone remember a show on Cartoon Network (I think it was, but I’m not sure) where there were 3 main characters and they used cards or something to get powers? One of them was a girl with blue hair and another, I think, was a boy with blonde hair. But the other boy (I think his hair was brown) was like the leader of the trio. And there was this villain that was the blue-haired girl's father. I think her name was like Nya or Mia Idek. But it was around the same time period as the 2004 Ben 10 and I thought I remembered the name, but there is no trace of it.


Count metric induced topologies on countable set.

How many topologically distinct metrizations of countable set are there? One can find countably many different ones by arranging points on a plane for example. Are there more than that? How would one approach this?


Is exponential map, $X \mapsto e^X$ for matrices injective?

As I know, exponential function is strictly monotonic increasing function. So it means that for $x,y \in \mathbb{R}$, if $e^x=e^y$ then $x=y$. But how about exponential matrix? If I have two matrices $X,Y$ satisfy $e^X=e^Y$, does that mean $X=Y$?


Sans serif upright lower-case Greek letters for beamer class

I use the beamer class with the cmbright package which provides sans serif Greek and Latin letters for the math mode and also sans serif-ish versions of math symbols such as \partial. Unfortunately, it does not seem to provide upright versions of the lower-case Greek letters. I know the upgreek package, but the letters it provides have a serif-ish look about them which does not combine nicely with cmbright.  Here is what I mean:  \documentclass{beamer}  \usepackage{cmbright} \usepackage[Euler]{upgreek}  \begin{document} \begin{frame} $\alpha\beta\gamma\delta\epsilon\varepsilon\zeta\eta \theta\vartheta\iota\kappa\lambda\mu\nu\xi\pi\varpi \rho\sigma\tau\upsilon\phi\varphi\chi\psi\omega$\\ $\upalpha\upbeta\upgamma\updelta\upepsilon\upvarepsilon\upzeta\upeta \uptheta\upvartheta\upiota\upkappa\uplambda\upmu\upnu\upxi\uppi\upvarpi \uprho\upsigma\uptau\upupsilon\upphi\upvarphi\upchi\uppsi\upomega$ \end{frame} \end{document}     Maybe someone knows a solution? Ideally, there should also be a way to get a bold version of the letters. Thanks a lot!


What do you mean by Ciphertext indistinguishability

Wiki definition :      A cryptosystem is considered secure in terms of indistinguishability   if no adversary, given an encryption of a message randomly chosen from   a two-element message space determined by the adversary, can identify   the message choice with probability significantly better than that of   random guessing (1⁄2). If any adversary can succeed in distinguishing   the chosen ciphertext with a probability significantly greater than   1⁄2, then this adversary is considered to have an "advantage" in   distinguishing the ciphertext, and the scheme is not considered secure   in terms of indistinguishability. This definition encompasses the   notion that in a secure scheme, the adversary should learn no   information from seeing a ciphertext. Therefore, the adversary should   be able to do no better than if it guessed randomly.   I understood the meaning of this but what do you mean by Indistinguishability under chosen-plaintext attack and Indistinguishability under chosen ciphertext attack ? Could anyone give me an example, and answer in easy understanding language.


When to use "than" and "of" in comparative sentences

The self-storage industry has three times the footprint than McDonald’s.   Or:     The self-storage industry has three times the footprint of McDonald’s.


Suppose I have following equation:  $$ a_1 + a_2+\cdots+a_k=n$$ $$a_1,a_2,\cdots,a_k\in\{m,m+1,m+2,\cdots,m+l  \}$$ and  $$m*k<n$$  I am asked to calculate how many different solution that equation has. What I came up with is changing variables: $a_i=a_i'+m$ and then my equation looks like this: $$ a_1' + a_2'+\cdots+a_k'=n-k*m$$ $$a_1',a_2',\cdots,a_k'\in\{0,1,2,\cdots,l  \}$$ It may seem a little nicer to solve but still there's that $l$ limitation which I am not so sure know what to do with. Is there any  "general" method to do this type of task? I already tried substituting one of variables like that: $a_i'=a_i''+l+1$ and then solving "smaller" equation but it just doesn't feel like the right way to do this.  My original equation is: $$a+b+c+d=45$$ $$a,b,c,d\in\{5,6,\cdots,15\}$$  I'll be thankful for any help or tips.


I have a problem undestanding the correspondance of my data to my principal components in PCA. I have a dataset of 50 columns and 20 samples. I use the mapcaplot to apply the PCA algorithm and come up with my plot. However I am unable to understand the meaning of the axes (PC1 and PC2) and therefore understand the linear combination of each of my variables. I also ran the pca algorithm and come up with the coeff matrix, the latent and scores. Still I cannot understand it. Could anyone point me to the right direction please?


How long should I quick soak my dry black beans?

Yesterday I decided I wanted to make a soup using dry black beans. At 11:30 I started soaking them in a glass container and transferred them to a pot 5 hours later to be quick soaked. How long should I soak & cook them?


Can I install more than two desktop enviroment in the same pc?

I want to try out a different desktop environment that my brothers using as it was looking pretty good but I have no experience using it. So I was just wondering if I could install it on my pc without deleting existing ones. I have KDE and gnome installed in pc and is it possible to install one more without deleting any of the existing two? If possible that also mention how many desktop environment can be installed in one system.  My current os is ubuntu 18.04.3  thank you!


Aside from just the idea that it has to be "something" (maybe lead, steel, whatever), what is it about silver that makes it so special that it can kill a werewolf where other bullets or a stake to the heart can't?


Sharing a FTB LAN world when one of us is offline

Me and my friend are using Tunngle to play FTB together using lan. When my friend is unavailable to host I had the idea for him to share the world save on Google Drive. This way I could play the game by myself, send the file back to him and he could host when we play together.   He sent me the file after we played together for a bit. When I put the folder in my save and booted it up I was playing as my friend, same location same inv.  Does anyone know a way that I could play as my own character as I left off when we were playing over Tunngle?


Why have the home releases of the recent Star Wars films been in March?

I've noticed that with Star Wars (at least the recent ones) the films get released in cinemas in December and then home release comes out March.   I get they target December for the cinema release because of the Christmas holiday period but is there a reason why the home release seems to fall in March? I don't recall any sort of holiday season for March.


How can I grep for a string containing regex metacharacters like $ and '?

I want to search all files in the current directory and below for the substring $form['#node']. So, I have tried, initially:  grep -R "\$form\[\\\\'" . and grep -R "\$form\[\'" .  But it returns no results. However,   grep -R "\$form\[" returns plenty of results, as there are instances of entries such as $form['#id'] or $form['#node'] in the files. Is there any reason why adding the escaped single quote causes an issue? I can't seem to find any clear indication of exactly how to escape a single quote in this case.  I need to check that my escaped characters are working as intended in this scenario.


now that there are past a few months. I do have the same Problem. I have an Dell Inspiron 17 5770 2018, Core i7-8550U, 16GB RAM, 2TB HDD, 256GB SSD (5770-0371)  and it has a graphicscard AMD Radeon 530, 4GB, HDMI.  I tried installing the driver on Ubuntu 16.04 and 18.04 . None of them is working. Is there a solution?


Would Gollum qualify, as a Ringbearer, to go to the Undying Lands?

If Gollum had not died in Mount Doom, would he have been allowed to join the elves, Bilbo, and Frodo in the Undying Lands?  He was, after all, by far the longest-lasting bearer of the One Ring (not counting Sauron himself before it was taken from him), which is the reason given for Frodo, Bilbo, and Sam’s being allowed to go there.  And would his being or not being allowed to go to the Undying Lands be affected by whether or not the Gollum part of him would vanish after the destruction of the Ring, leaving only Sméagol behind?  Note: As Richard’s answer (with comments) points out, there are various logistical practicalities that would likely get in the way of Gollum ever getting anywhere. However, what I am asking here is whether whoever decides who is and isn’t allowed to go to the Undying Lands would consider Gollum, as a Ringbearer, qualified to go there.


I'm trying to conduct a two sample t-test on  on food and drink workers in the Seattle MSA to see if there is a mean difference in levels of employment before and after the enactment of an increase in the minimum wage after April 1, 2015. The background for this project is that many people say that an increase in the minimum wage will force low-skill employers to cut their staff in order to minimize costs.   I've included my code below but I'm not certain it's correct. I separated the data into two variables (observations before and after the minimum wage increase took effect), but why am I getting such a ridiculously small P-value? Is that correct? Any help is appreciated.   #seattleData <- read.table(file=file.choose(), 2 # header=T, sep=",",) food_drink_workers <- seattleData$food_drink_workers afterMinWageLaw <- food_drink_workers[304:346] beforeMinWageLaw <- food_drink_workers[1:303] boxplot(beforeMinWageLaw, afterMinWageLaw) options(scipen = 100) t.test(beforeMinWageLaw, afterMinWageLaw, mu=0,      alternative "less", conf=.95,      var.equal = FALSE, paired = FALSE)   Results:  Welch Two Sample t-test  data: beforeMinWageLaw and afterMinWageLaw  t = -36.92, df = 160.8, p-value < 0.00000000000000022  alternative hypothesis: true difference in means is less than 0  95 percent confidence interval:  -Inf -38.87279  sample estimates:  mean of x mean of y  103.8059 144.5023


Why is the df for the χ² test of independence (r − 1)(c − 1)?

I understanding that if Z1, Z2, …, Zk, are independent standard normal variables, then Z12 + Z22 + … + Zk2 has a χ² distribution with k degrees of freedom.   However, say we have a 2 rows and 3 columns, then we're taking (observed - expected)2 divided by expected for 6 cells. Why then is the degrees of freedom not 6?


I am currently using SE app for Android. I just posted a travel question but could not create a new tag for my question.  I know that:   This is SO meta, and my issue is with travel, but I am afraid that this applies to all SE sites 2 I don't have yet enough reputation to create a tag autonomously on Travel like I can on SO, but at my level it should be possible to peer review tag creation requests   Is it possible to create question tags from android SE app? I have tagged this question with only existing tags but could not find a way to create a new one. On the site, if you tab/enter without picking an existing tag the page will propose to create, but eventually can fail when you submit the form if you have very low rep (this MIGHT have changed by the time I had low rep on SO)  OR it is just that I haven't yet learned to use the application


Similar question search works better than actual search

I wanted to open a question titled "What's the best SQLite Cocoa library?". The suggestions told me that the question might be closed for being subjective, but also suggested some similar questions. The answer I found this way was better than the answers that I found when I searched using the search box. In fact, the question I found didn't even appear in the list from the direct search.   Is there some way to use the better search without opening a question? Is there a reason they're so different?


Show that $\mathbb{Z}[\sqrt{-2}]$ is unique factorization domain. I am unable to proceed. Any help, thanks in advance.


My problem is when in an open javafx project and try to run it without editing it, an error appear like this, and everything install for java FX.


Why can't I sculpt on a plane when using Subdivision Surface?

When I add Subdivision Surface I just simply can't sculpt anymore, but...it works with multiresolution...any ideas why is that?  Thanks


What is the term for a word that has come to mean the opposite of its orignal meaning?

What is the term for a word that has come to mean the opposite of its original meaning"


Should I include name of potential advisor on my statement of purpose (SOP)

I am currently writing my statement of purpose (SOP) for top graduate schools in engineering majors in US. I am wondering should I include name of my potential advisor on my SOP (Is it a good idea to do that)? The problem is I am thinking if I do not include name of advisor it might be the sign I did not look at his/her research page and I am not very specific about my plan. On the other side, if I include name of potential advisor and my application is not competitive or he/she is not accepting any graduate student this might cause others not to look at my application since they might think I am not interested in their research.


How to remove coolrom.com malware from ubuntu?

I've been dumb and downloaded the malware from coolrom that inputs some sort of """search engine""" in firefox. I'm trying everything to clean that but without success. Someone knows how should I do it?


Casting operands in floating point comparison works not as expected

When I want to compare two floating points values. I get strange results.  My example compiled with x86_64-w64-mingw32-g++ test.c -mfpmath=387:  #include "math.h" #include "stdio.h" int main(int argc, char **args) {      double t1 = atof("999990") * 1e-9;     double t2 = atof("999990") * 1e-9;     printf("1) Compare of two variables \"t1 != t2\": ");     if (t1 != t2) {         printf("Not Equal\n");     }     else {         printf("Equal\n");  //This is taken     }     printf("2) Compare of Variable with calculated value \"t1 != atof(\"999990\") * 1e-9\": ");     if (t1 != atof("999990") * 1e-9) {         printf("Not Equal\n");  //This is taken     }     else {         printf("Equal\n");     }     printf("3) Compare of Variable with casted calculated value \"t1 != (double)(atof(\"999990\") * 1e-9)\": ");     if (t1 != (double)(atof("999990") * 1e-9)) {         printf("Not Equal\n");  //This is taken??     }     else {         printf("Equal\n");     }     return 0; }   First comparison: OK  Second comparison: OK (assuming right term is a 80Bit precision)  Why evaluates the third comparison to unequal? Why is the cast to double not recognised? Why is the result of the comparison different than the first case?


Why does grep not work with redirection?

Using the top command with redirection works fine:  top > top.log   Now I want to use grep to filter a certain line:  top | grep "my_program" > top.log   But the log file will remain empty. But grep delivers an output when using  top | grep "my_program"   Where my_program has to be replaced by a running program to see some output.  Why does my approach not work ? And how can I fix it ?


preg_replace on the actual match ( index 1) instead of whole string

Consider  preg_replace('/(lets go).*/', "going", "lets go somewhere")   It will output: "going", I want "going somewhere".   preg_replace seems to replace using the first match which is the whole string "lets go somewhere". How can I make it ignore index 0 and only target index 1?


A user on the Ask Ubuntu General Room posted a link to . After some googling around, all I can find is that it is a mysterious security bug, that uses the same website template as Heartbleed.  I manage Linux Servers, a mysterious security bug does not sit well with me. What exactly is it, and how can I protect my servers from it?


Are these two sentences distinguishable on contextual grounds?

1) Let me see if I can find a match on tinder?  2) Let me see if I could find a match on tinder?  For instance, in healthy banter with your friend, you tell him he's so ugly that no one would swipe right on him. He rebuts in either of these counter statements.  (As for my own rationale: the first sentence conveys an 'ability' while second implicates a 'possibility')


Migrating from Windows 10 to Ubuntu 16.04 LTS without loosing data in "D:" drive

I have two partitions on my hard drive. One with Windows 10 installed and the other with my personal data, "C:" and "D:" respectively. I want to remove windows from that machine and install Ubuntu on it (no dual-boot). Is there a way by which I can install Ubuntu without loosing data on "D:". And, is it possible to mount "D:" as "/home" in Ubuntu during installation? If it is possible, then how to do it?  Thanks in advance.  EDIT: I was not asking . Instead, I was saying can I mount that "D:" partition as "/home" by converting it to ext4 without formatting it.


Preseed values for keyboard-configuration

I'd like to activate ctrl+alt+backspace on multiple pcs (Ubuntu 14.04) using  dpkg-reconfigure keyboard-configuration   I don't want to do the dialog every time so i tried:  debconf-get-selections | grep "^keyboard-configuration" > config.dat   on a host where i answered the dialog with the desired answers  On the host where i want to do it non interactively i tried:  debconf-set-selections config.dat  dpkg-reconfigure -f noninteractive keyboard-configuration   it ran without asking, but afterwards the selections where reset to the default values  How can i get dpkg to use my predefined values? Or is there another possibility to enable the ctrl+alt+backspace for all users without going through dialogs?  EDIT  to summarize: my problem is that  dpkg-reconfigure -f noninteractive keyboard-configuration   doesn't seem to respect my preseeded selections. Can anyone find something wrong in the procedure how i try to do it or could this be a bug?


Data extension values in the "Update Contact" activity in Journey Builder

I'm looking for a way to use fields from a data extension (that is the entry source for a journey) in the "Update Contact" activity.  I want to create a sort of log in a different data extension. Let's say I have a sourceDEthat is used by the journey and a journeylogDE where I would like to write the email of contact that's currently in the journey.  What should I write in the value field to get a value from the currently used record in the sourceDE?  I tried {{Contact.Attribute.sourceDE.email}}, but it did not return any values.   I would appreciate it if you could give me any tips how to fix this issue.


How to change horizontal alignment of \frac?

Typing \frac{W+W^*}{2} gives a fraction in which the denominator appears to the eye to be in the wrong position. Is there a way to correct this, i.e. place the 2 in under the + (without using arbitrary negative spacing)?


Matrix exponential of a traceless $2\times2$ complex matrix

How to calculate $\exp\left(t\begin{bmatrix}0 & z\\z^* & 0\end{bmatrix}\right)$, or $\exp\left(\begin{bmatrix}0 & v\\w & 0\end{bmatrix}\right)$ (where: $v, w \in \mathbb{C}$) in general?


Problem with brackets in more than one row

I format my equations with an array to have them look nicer. I also use the \left( and \right) for brackets. One part of the equation is too long and needs to be splitted into two lines. This is my try so far  \begin{array}{ccl} x & = & \left( … long term… \\ & & … long term … \right) \end{array}   But this gives me the error missing \right. There is defenely no other missing \right) involved. If I remove the first \left and last \right it works, but I still want to keep my adjusted brackets. How to solve this?


What kind of RAM does a 2010 motherboard support?

Thanks for Zeiss Ikon' s comment. A:     I have an old computer. The motherboard is made in 2010.  It is missing a RAM card so I bought a DDR3 1600 RAM. But the motherboard does not support it.  What kind of RAM is suitable for a 2010 motherboard? Thanks.  EDIT: I cannot start Windows, so using software is not a solution.


I am facing the error parameter Id is missing,while conga composer from VF page button click

when i select the records in vf page ,after click on the VF Button the conga should be call along with id for generating the PDF but on button click the window is opening but showing error that "ID Parameter is missing" ? how to over come the issue? your reply will be appricated ,please reply asap.  vfpage:  <apex:commandButton value="Generate Invoice" action="{!GenerateInvoice}"  onclick="openConga(setOfIds)" reRender="table1"/>  <script> function openConga(setOfIds){   if(setOfIds !=Null){   var Formastring=setOfIds.splits(',');   var joinIds=Formastring.join("'|'");   var removeSpace=joinIds.replace(" ","");   var removeLeft=removeSpace.replace("[","");   var removeRight=removeLeft.replace("]","");   var finalSetIds=removeRight;    var CongaUrl ="/apex/APXTConga4__Conga_Composer?sessionId={!$API.Session_ID}" +"&serverUrl={!$API.Partner_Server_URL_290}&Id={!Payment_Id}" +"&QVar1Id=[sql1221]a186C0000007yB3?pv1=" + finalSetIds +"&TemplateId={QVar1}";  window.open(CongaUrl, "Conga","menubar=no,height=600,width=800");    } } </script>   controller:  [28-01-2019 12:13]  Sakhare, Ankita:   public PageReference GenerateInvoice() {     selectedEsr = new List < Payment__c > ();     for (wrappayment wp: paymentList) {         if (wp.selected == true) {             Payment_Id = wp.pay.id;          }     }      return null; }


I have a simple class which will be useful for me with generating random numbers using default_random_engine.  Random.h:  #include <random>  using namespace std;  class Random {     public:         Random();         ~Random() {}     private:         static default_random_engine _engine; };   Random.cpp:  #include "Random.h"  Random::Random() {     _engine = default_random_engine{}; //Will this be initialized every time I create an object of type Random? }   Will _engine be initialized every time I create an object of type Random? I just want it to stay like it is after the first initialization because I was told I can use the same engine multiple times.


Flag panel no longer has "you have already raised this flag"

Previously, I was unable to select a flag when I had already flagged it, however now when I flag I am still able to select it, only to find when I have clicked it that "You have already flagged this post for moderator attention".  Is this a bug, and if so, can this be fixed?


Why is a unified field theory necessary?

I have read almost everywhere that the biggest questions in physics is to unify all the fundamental forces but I simply do not understand why do the forces have to follow a same set of rules or why is unification of Forces necessary?


I have looked through a post of structure padding in geeksforgeeks,   But I don't know why in this case:  int main()  {       struct C {          // sizeof(double) = 8          double z;           // sizeof(short int) = 2          short int y;          // Padding of 2 bytes           // sizeof(int) = 4          int x;      };       printf("Size of struct: %d", sizeof(struct C));       return 0;  }    I know y (short int) is followed by x (int) and hence padding is required after y. But why the padding here is 2?


Memory leaks in my Java server application

I have a simple Java server application implemented using com.sun.net.HttpServer API. It receives REST requests almost every second, reads a large HashMap for some texts and simply sends back the texts after some processing. The server part simply looks like this:  public class Server implements Runnable {     static final Logger logger = LogManager.getLogger(Server.class);     static int serverPort = 9002;     HttpServer server;      public Server() {         Thread t = new Thread(this);         t.start();     }      public void run() {         try {             server = HttpServer.create(new InetSocketAddress(serverPort), 0);             logger.info("EventRetriever REST server listening to port: " + serverPort);             server.createContext("/getEvents", new MedatadaHandler());             server.setExecutor(null);             server.start();         } catch (IOException e) {             logger.error(e);         }     }      class MedatadaHandler implements HttpHandler {     @Override             public void handle(HttpExchange he) throws IOException {             //...             String response = requestEvents();             he.sendResponseHeaders(200, response.length());             OutputStream os = he.getResponseBody();             os.write(response.toString().getBytes());             os.close();     } } //some other functions...      public String requestEvents(){     //read from a HashMap, some processing, creating a JSON and sends it while logging it in file             logger.info(jsonString);             return jsonString;     } }   }  While running as a docker container, I see the memory usage increases over time, like an average of few MB over few seconds. Apparently, somewhere here we have a memory leak. Is it the unused objects, the j4logger loggings, or whatnot, I don't really know. I just tried to call a System.gc() explicitly once every few minutes. It does some remedy, but I am not sure where the problem is coming from.   What is the problem and how to fix it?  EDIT: how do I know the problem is coming from this part of program? Well, I have other thread responsible for filling those HashMaps every 5 mins, then going to sleep. Even when that's on sleep, I see memory increase. The only part is this server which is serving every second.


How to prevent inline link URL from counting towards comment length limit?

Is there a way to prevent an inline link URL (the one in parentheses) from counting towards the comment's length limit? How? If not, please implement this. Is there another input technique to make only the human-readable portion count?


How can I summon Lighting in a certain spot?

For a little things I'm doing I need to make charged creepers. However, finding one in the wild is almost impossible and I need to have people see the creepers change into charged creepers, therefore using /summon to summon a charged creeper won't work. Is there a command to summon lightning?


My original laptop charger broke, so I got another one that is similar. The problem is that the 2nd one broke too. I found a different one, but don't know would it work. My laptop battery is completely dead and won't charge. Laptop requirements: +19v = 3.42A 65w Charger I found: 24v = 5A (24vdc) I'm not very familiar with voltages and stuff, but would it work? And does it Change a lot if the requirements are +19v and not just 19v?


Account for spatial autocorrelation with a binomial regression model

I am using a binomial regression model for presence/absence, with 20 independent variables to test. The data has x and y coordinates and I would like to understand how can I take into account the spatial autocorrelation.  I already studied the correlation between the variables and run the same model for 1000 different samples (I have a big dataset that allows me to do this) to understand the distribution of each parameter and check for variables that might be introducing problems in my model.   glm_model <- glm(PA ~ Var1 + Var2 + Var3 + Var4 + Var5,family=binomial(link=logit))  However I believe I also need to account for spatial autocorrelation. I saw that there is a package that might help me (spdep), however I am not sure I completely understand if I can use my model or not. My question is what are my options ?


this is the work I need to reproduce, kindly help with the coding

The page above has work am trying to reproduce but the Greek numeration with marks in parentheses(bold) and the tree diagram have given me trouble. I don't seem to be getting it right. Am new to latex, so kindly help me.


Prove that any set of 2015 numbers has a subset who's sum is divisible by 2015

I assume this is correct to any size set, not 2015 in particular... it's obviously true for 2. I know from pen and paper it's true for 3, and 4....  I understand that I should look at the reminders, and build pigeonholes from them.  If one of the numbers has a 0 reminder obviously the entire set is divisible, so the possible reminders go from 1 to (n-1). i have n numbers hence one of the reminders repeats. the sums of the reminders go from 1 to n*(n-1)....  And that's it...  Any and all help would be appreciated.    Of course I mean non empty set...


Can a photon be called a disturbance in the electromagnetic field?

Total noob here.  I know that electromagnetic waves do not need a medium to travel. I analogize a photon as a single pulse/oscillation in the electromagnetic field and its propagation is the motion of that pulse through the electromagnetic field. Kind of like the pulse that travels through a string if you jerk it.


Will Windows 10 erase all my files if I upgrade from Windows 8.1?

I have the little Get windows 10 icon in my toolbar now, and I'd like to update, but I'm afraid that it'll erase my files. If I update from Windows 8.1 to Windows 10 will my data get erased? For those who don't know, this is the icon.


Why are there so many places to put a binary in Linux? There are at least these five:   /bin/ /sbin/ /usr/bin/ /usr/local/bin/ /usr/local/sbin/   And on my office box, I do not have write permissions to some of these.  What type of binary goes into which of these bins?


How to achieve a realistic material for an operative phone screen?

I'm trying to recreate an electronic device where the screen is ON - like this:     I can easily achieve the off version, just a glossy sharp black material, but as regards the "on" version, displaying an image that looks like it is behind a pane of glass and "emitting" a texture, so to speak, I have no idea.


Why is 5[a] valid and does not generate an error of invalid identifier?

In  it is explained that the [] operator in a[5] is defined as *(a + 5) and because + is commutative, 5[a] means *(5 + a) and so the two expressions refer to the same memory location. Fine.  However, C also defines in 6.4.2.1 that an identifier cannot start with a digit. In 5[a] the array identifier is 5 which is not a valid identifier. Why does 5[a] not generate an error about an invalid identifier?


For example:  $(a+b)^2 = a^2 + b^2 + 2ab$  $(a+b)^3 = a^3 + b^3 + 3ab(a+b)$  So my doubt regarding these identities are why does the identity differ when the power is changed and is there any derivation for it?


Installed Ubuntu 15.1 on USB (full install) but it won't boot

I'm still a newbie with Linux but I'm trying to learn. I have two USBs, one is 4GB and has the ISO install of Ubuntu (I think it's called live, the one with maximum of 4GB of permanent storage) and got a 64gb usb to make a permanent full install on it. I installed it following  tutorial and everything looks fine (I had to create the EFI partition with the Terminal though) but it just won't boot, the live install boots without problems.   I'm using the school's computers which have the UEFI menu password protected so I can't access that and I won't have a laptop for like 3 weeks (main reason why I'm doing this). I tested it with a friend's laptop disabling the Secure boot but it still wouldn't boot. I also saw that some tutorials don't add the EFI partition so I tried without that one and still won't work. And I know it's not the 64GB usb not booting because I had a live install on it too before and it booted fine.  Please, I have been trying to make it work for two days now, any ideas? I can barely understand this stuff so if you could explain step by step that would be awesome.


Prove that if $R$ is a non-commutative ring with $1$ and if $a,b \in R$ and if  $ab =1 $ but $ba \neq 1$ then $R$ is infinite  I'm not sure about this one.  I noticed that $ba$ is an idempotent, and thus $(1-ba)$ is idenmpotent... So far I have 5 elements wooh! Only need $\infty$ more! Haha but seriously i'm pretty confused, insight appreciated!


Existence of a measurable cardinal $\kappa$ by the existance of $\kappa$-complete ultrafilter

Let $U$ be a countably complete free ultrafilter over S. Prove that there is an uncountable cardinal $\kappa, \kappa \le |S|$ with a $\kappa$-complete free ultrafilter over $\kappa$.   Is the following attempt correct:  I say that $\kappa$ is the smallest cardinal such that the intersection of $\kappa$ many members of $U$ is not a member of $U$ and assume a sequence {$A_{\alpha} : \alpha \in \kappa$} and $B_{\beta}$= $\bigcap$ {$A_{\alpha} : \alpha \lt \beta$}\ $A_{\beta}$. Now I need to prove that there is an ultrafilter that contains $B$ and I am stuck there.


Salts, how does the script know what the salt is?

I am new to PHP programming and trying to grasp the idea of hashing and encryption for protecting passwords, credit card details and such. I've done a lot of reading about MD5 which I think I understand the basics of now. I've seen places recommending that I use SHA2, which I don't understand how to implement.   Back to my question. I can understand how a script can tell if a password is correct or not by hashing the password and comparing the value against the hashed one in the database. My problem occurs when trying to understand salts. If I have a dynamic salt such as the date (yes, I have heard its a bad one to use), how does the script know that a password is correct because the salt will be different for the entered password and the one stored in the database.  For example: Say the original password was created on the 21/02/2011:   unhashed with salt:  mypassword210211  hashed with salt:  cbc0a790b2f28fc72ca43eb749028b9f    Then if I check my password today:   unhashed with salt:  mypassword30012012  hashed with salt:  e4af7ca7e263750a15be642d903c9ac9    They're completely different, so how does the script know that they are the same? Do I have to store the salt used on the specified password in the database so it knows what to use next time?  I'm rather confused and its highly likely that I am not understanding the whole hashing process properly. I've done my research, but whether I have done correctly or not I don't know.


Let $X$ be a geometric random variable with parameter $\theta$ find $m_X(t)$

Let $X$ be a geometric random variable with parameter $\theta$ find $M_X(t)$, moment generating function.   $m_X(t)=E(e^{tX})=\sum_x e^{tx} p_X(x)$  $$\sum_x e^{tx} p_X(x)= \sum_x e^{tx}(1-\theta)^x\theta$$ $$=\theta\sum_x[e^t(1-\theta)]^x$$  I need to simplify $\sum_x[e^t(1-\theta)]^x$   To do this I could use $\sum_{k=1}^{\infty} q^k = \frac{q}{1-q}.$   However, how to show that $e^t(1-\theta)<1$?  But I'm not sure how to do this.


Connection between t and F distributions

We have: $Z\sim N_{0,1}$ (standard normal distribution) , $U\sim X^2_{k}$ ($X^2$ distribution, with k df) with $Z \bot U$ Then $X = \frac{Z}{ \sqrt{U  /k} } \sim t (k)$ (t-distribution, with k df) I am missing how $X^2 \sim F(1,k)$


Why have "my" and "your" been used in place of "me" and "you" in "...There is no connection between **my** having no pencil and **your** having..."

Following is an excerpt from , by Albert Einstein and Leonard Infeld:     Let us follow the motion of the idealized car on the idealized switchback as it begins to roll downward from the starting-point. As it moves its distance from the ground diminishes, but its speed increases. This sentence at first sight may remind us of one from a language lesson: "I have no pencil, but you have six oranges." It is not so stupid, however. There is no connection between my having no pencil and your having six oranges, but there is a very real correlation between the distance of the car from the ground and its speed. We can calculate the speed of the car at any moment if we know how high it happens to be above the ground, but we omit this point here because of its quantitative character which can best be expressed by mathematical formulae.   I wonder why have the author used "my" and "your"  in place of "me" and "you" in the sentence, "...There is no connection between my(me) having no pencil and your(you) having six oranges..."  I am confused, about when to use "me" and when to use "my". E.g in the following sentence should I use "me" or "my"?     I was in real, no King, of the forest in the past. I am asking the Tiger to imagine a scenario in which I be king of the forest in past. Since, the sentence is present perfect the fact of my being the king in the past has present consequences and I am for sure, not King of the forest at present in that imaginary scenario --- the consequence is the fear of me in the pythons. The Tiger thinks that the fear in the Pythons would be because of something else not because of my(me?) being the King in the past. I am asking him, wouldn't my being the King in the past enough to make a fear of me in pythons?   Please explain me in simple English, when to use me and when to use my, while referring to myself? How do the sentences appear to native English speaker, when we replace me with my? I do not know technical English grammar, like gerund, verb or noun things.


why does echo "something" >> file disappears? (written by another process)

I'm redirecting the stdout and stderr of a 3rd party process to a log file. I want to add markers to that log file, they disappear when I get the final file.  3rdParty-process &> log & <<3rdParty-process prints a lot to stdout>> echo "myMark" >> log cat log #my mark is here <<3rdParty-process prints a lot to stdout>> cat log #my mark is NOT here   Any ideas?


Why does `ls -d *[!e]*` display all files instead of omitting all files that contain an e?

ls -d *e* prints out all files containing an "e" somewhere in it. But the opposite, ls -d *[!e]* does not seem to work. Why exactly is that?  is it because ls takes * as its own argument and expands all the files?  I understand I can do: ls -d !(*e*) (in Bash with extglob set, or in ksh).


Today I'm having hard time with linear algebra problems; this is one:  $\forall A,B\in M_n(\mathbb{K})$,   $\mathrm{rank}(A)+\mathrm{rank}(B)\le \mathrm{rank}(AB)+n$  $M_n(\mathbb{K})$ is the space of square matrices in the field $\mathbb{K}$, for instance $\mathbb{C}$ or $\mathbb{R}$.  .  If I consider A and B as linear mappings from $\mathbb{K}^n$ to $\mathbb{K}^n$ I have:  $\mathrm{rank}(A)=\mathrm{dim}(\mathrm{Im}(A))=n-\mathrm{dim}(\mathrm{Ker}(A))$  $\mathrm{rank}(AB)=n-\mathrm{dim}(\mathrm{Ker}(AB))$  so, the inequality becomes:  $\mathrm{dim}(\mathrm{Ker}(A))+\mathrm{dim}(\mathrm{Ker}(B))\ge\mathrm{dim}(\mathrm{Ker}(AB))$  Is this correct? Now, how can I conclude?  .  I thought that if $\mathbb{K}=\mathbb{C}$ then A and B are for sure triangularizable and then, maybe in some way developing the products I can show directly that the inequality holds??  .  Thank you.


How to horizontally center a div-block containing images?

I'm trying to horizontally center a div-block containing images (playing cards placed there by Javascript), but somehow it doesn't work (images are still left-aligned). Here's the HTML:

   And here's the CSS:  #dealerarea{ position:absolute; width:100%; height:96px; top:15px; } #dealercards{ display: block; margin-left: auto; margin-right: auto; }   What i'm doing wrong? Thanks in advance!  Edit: I can't give a fixed "width" to inner div, because it changes every time (depending on the number of card images).


In the Harry Potter movies, Ron, Harry and Hermione joke about how old Dumbledore is, but end up laughing. I wondered how old he was, since he 'invited' tom riddle to Hogwarts....etc.


In the following code :  magicnumber = 256 for n in range (500):     if n is magicnumber:         print ("the magic number is " , n)         break     else:         print(n)   The loop breaks at 256, but if you set magicnumber to 257, it doesn't. Why ?


Prove using contradiction that any prime number greater than $3$ is of the form $6n \pm 1$.  Thanks for any help