On my server, the root partition is 73GB, but the disk says, it is full, although there are only about 6GB used on that device:  # df -h Filesystem                  Size  Used Avail Use% Mounted on udev                        997M     0  997M   0% /dev tmpfs                       202M   41M  162M  20% /run /dev/mapper/p22server-root   73G   68G  655M 100% /   (I use LVM on the server: /dev/mapper/p22server-root -> ../dm-0) If I check with   ncdu -x /   I find out that the total usage is just 5.9GB.   My guess is, that there must be files still open, that are not visible in the file-tree.   How can I debug this? I guess, that a reboot will restore the lost space, but rebooting is not possible right now.

I have a small ext3 / partition on a 2T drive which appears to have a discrepancy in its free space. How can I determine what is causing it and how it can be fixed.   After trying everything I could think of, I forced a fsck on boot which didn't have any affect.  I have other systems configured identically which don't exhibit this condition.  # df -h / Filesystem            Size  Used Avail Use% Mounted on /dev/sda1             9.7G  8.9G  318M  97% /  # du -shx --max-depth 1 / 5.2G    /  # lsof | awk 'BEGIN {t=0} /(deleted)/ {t+=$7} END {print t}' 0  # tune4fs -l /dev/sda1 | grep -E 'state|Free|Reserve|size|Inode' Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file Filesystem state:         clean Inode count:              2621440 Reserved block count:     131029 Free blocks:              212317 Free inodes:              2487281 Block size:               4096 Fragment size:            4096 Reserved GDT blocks:      639 Inodes per group:         32768 Inode blocks per group:   1024 Reserved blocks uid:      0 (user root) Reserved blocks gid:      0 (group root) Inode size:               128   Edit:  fsck says the partition is 2% non-contiguous.  For comparison to du above (sparseness):  # du -hxs --apparent-size / 4.9G    /


Show $${n \choose 1} + {n \choose 3} +\cdots = {n \choose 0} + {n \choose 2}+\cdots$$  A hint is given to consider the expansion $(x-y)^n$  However, when I plug in a number for $n$, I don't get an equality. $n=5$, for instance, I get $5+10 = 1 +10$.  How is this equality possible?

Can someone give me a hint how to evaluate $$ \binom{n}{0}+\binom{n}{2}+\cdots+\binom{n}{o(n)},$$ where $o(n)$ is $n$ if $n$ is even and $n-1$ otherwise ?


Im getting this strange NullpointerException whilst adding a JLabel to a JPanel:      loadoutAdvWeaponPanels = new JPanel[4][4];     loadoutAdvWeaponButtons = new JButton[4];     loadoutAdvPistolLabels = new JLabel[4][8];      //Init loadoutAdvPanels[0]      loadoutAdvWeaponButtons[0] = new JButton("Pistols");      loadoutAdvPistolLabels[0][0] = new JLabel("USP-S");     loadoutAdvPistolLabels[0][1] = new JLabel("P2000");     loadoutAdvPistolLabels[0][2] = new JLabel("Dual Berettas");     loadoutAdvPistolLabels[0][3] = new JLabel("P250");     loadoutAdvPistolLabels[0][4] = new JLabel("Five-SeveN");     loadoutAdvPistolLabels[0][5] = new JLabel("CZ75-Auto");     loadoutAdvPistolLabels[0][6] = new JLabel("Desert Eagle");     loadoutAdvPistolLabels[0][7] = new JLabel("R8 Revolver");      loadoutAdvWeaponPanels[0][0].add(loadoutAdvPistolLabels[0][0]);   The error occurs in the last line, but i dont know why.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I want to show the following:  $$ \sum_{r=1}^\infty \frac{1}{r(r+1)} = 1. $$  I've found this series as part of a calculation to prove a formula for the Gamma function. I know it converges to 1 because of the result of this calculation, but otherwise I wouldn't even know how to find this value, so any help is appreciated with how to find out the series converges to 1 and/or how to prove it converges to 1 (in case these steps are done separately).

I am confused on the following series: $$\sum\limits_{n=1}^{\infty}\frac{1}{n(n+1)} = 1$$ My calculator reveals that the answer found when evaluating this series is 1. However, I am not sure how it arrives at this conclusion. I understand that partial fractions will be used to create the following equation. I just don't understand how to proceed with the problem. $$\sum\limits_{n=1}^{\infty}\left(\frac{1}{n}-\frac{1}{n+1}\right) = 1$$


I have a string. Something like this:  myapp.exe email --to myemail@mail.com --subject "EmailSubject" --body "Test message".   How to parse every param value?

When building console applications that take parameters, you can use the arguments passed to Main(string[] args).   In the past I've simply indexed/looped that array and done a few regular expressions to extract the values. However, when the commands get more complicated, the parsing can get pretty ugly.    So I'm interested in:   Libraries that you use Patterns that you use   Assume the commands always adhere to common standards such as .


When sending mail from a different account (say beta@gmail.com) than my default in Gmail (say alpha@gmail.com), when someone reply to me I can see that my alpha@gmail.com is mentioned in the conversation along with beta@gmail.com.   For example:     From: alpha@gmail.com on behalf of beta@gmail.com   Also, I tried to send myself mail to gamma@gmail.com from beta@gmail.com (through alpha account) and when clicking the show original in the message I can see my alpha@gmail.com there.  When I send mails from beta@gmail.com I don't want the recipient to know about alpha@gmail.com. Is there any way to prevent that from happening other than logging out from alpha and logging in to beta?

Related to , I want to remove the "On Behalf Of" when I send an email from another Gmail account via the web ui. So, as of now, my email is being shown as From emailA@gmail.com on behalf of emailB@gmail.com. When inputting the email into the settings, Gmail appears to detect that the email is another Gmail account and does not ask you whether or not to use another SMTP server. Anyone has any ideas on how I can get around this?


NOTICE: This is NOT a duplicate!! The title is REMOVE not DELETE. The UNJOIN feature is what I was after. Please read the full post. I hope this clarifies the difference.  How do I remove myself from a community? I don't recall how I joined one perhaps an accidental mouse click. But I would like to know how to 'unjoin' a Stack Exchange community.  To clarify, this is NOT an account delete request, only to 'UNJOIN' a community or two.  UPDATE: There needs to be clarification about the DELETE and UNJOIN. I found the DELETE postings and wanted to be clear in this post that I DO NOT want to DELETE, only UNJOIN.   Go ahead and delete this message as I did not intend to duplicate the other questions that ambiguously mix DELETE with UNJOIN.

How can I delete my Stack Exchange account(s)? Also,  What happens to my content? Can I request it be deleted as well? What if I'm suspended, rate-limited, or banned from posting questions or answers? What will happen to my votes? Will other users be impacted? Why wasn't my account deleted immediately after the timer expiring? What will happen to my pending bounties and close, reopen, delete, or undelete votes? I want my account deleted on all Stack Exchange sites. How do I do this? Will my profile on chat be removed once I delete my site account?   For more information, see "" in the .


Question: Let $f:S^2\to S^2$ be a continuous map that is homotopic to the identity. Does $f$ necessarily have a fixed point?   I thought about this question after learning the proof of Brouwer Fixed Point Theorem with de Rham cohomology. I hoped to be able to prove the affirmative with a similar proof, but all my attempts failed.  My intuition that it should be true started from two facts:   If $f$ is a rotation of the sphere (i.e. $f\in SO(3)$) then $f$ has two fixed points. The . Intuitively, if $f$ is homotopic to the identity we can imagine a flow from each $x\in S^2$ to its image $f(x)$. This flow must have a stationary point $x_0$, meaning that $f(x_0)=x_0$.

Suppose $\phi:\mathbb{S}^2\to\mathbb{S}^2$ is a mapping, homotopic to the identity map.  Show that there is a fixed point $\phi(p)=p$.


I'm describing parameter search using a particle filter, for which I use .  On page 8 of the document, he states "and $p(\theta)$ is (approximately) a mixture of multivariate normal distributions,  $p(\theta)=\sum_{j=1}^{n} w_j N_p(\theta \mid m_j, M_j)$."  where $N_p(\mu, \Sigma)$ is a p-variate gaussian distribution.  I.e. he's using a conditional probability inside a Gaussian PDF. Is that notation allowed? I've not seen that anywhere. My professor (i'm a PhD student) says it's incorrect.

So I'm reading notes on Gaussian Processses, and came across  syntax $p(\mathbf{y} \mid \text{stuff}) = N(\mathbf{y} \mid \mathbf{0}, \mathbf{K})$ for multivariate normal distribution, and I'm not exactly sure how to decipher it the $\mathbf{y} | $ bit. I suppose it doesn't mean "mean $\mathbf{y}$ is conditional on zero vector", because I don't think that makes sense. Assuming this is standard notation for something and I'm just unfamiliar with it, what it means? E.g. how it differs from $N(\mathbf{0}, \mathbf{K})$?


I saw a part of this movie on TV a few months ago, and I don't know its title.   Details:   It was set in north america, after a nuculear holocaust. In it there were two warring factions, one made up of females and one made up of males. One of the scenes I remember is one of the males finding the United States presidential bunker in the middle of the desert they lived in.  They say 'president' like 'Prezz - ee - dent' They get a hazmat suit out of the bunker and one puts it on, and they take some hand grenades from the bunker and make a show of force outside the women's faction camp. The name of it was something like "America 5000"   What is the name of this movie?

This post-apocalyptic movie was probably made in the 80's.  It plays in a matriarchal society, where men are slaves. I remember only one scene, where the main guy escapes a camp of women (the women are like Amazons) and by accident he falls into a cave (the scenery is similar to Grand Canyon). It turns out that the cave is a long lost, hidden fort, and he is in a control room. He sees monitors and computers, and a recording starts where he sees how the human civilization was before the apocalypse, skyscrapers, and such stuff. I think that before that, nobody knew what happened, and how the old world was at all.


I'm trying to solve the following  $$\lim_{x\to \infty} \sqrt[x]{p(x)}$$  where $p(x)$ is a polynomial of finite degree.  I've tried to use the continuity of $\exp$ and $\log$ :  $$\exp(\log(\lim_{x\to \infty} \sqrt[x]{p(x)}))=\exp(\lim_{x\to \infty}\log( \sqrt[x]{p(x)}))=\exp(\lim_{x\to \infty}(\frac{\log(p(x))}{x})$$  I would like to conclude that the limit is zero so it turns out to be $e^0=1$ How can I do it rigorously? I've seen that log is asymptotically slower than x. I would get it if in the denominator there was $p(x)$ with a change of variable.

Let $ p(x)=\sum\limits_{k=0}^{d}a_kx^k $ polynomial such that $  \forall x>0, p(x)>0 $     Prove that:   $$ \lim_{n\to\infty}\sqrt[n]{p(n)}=1 $$


In brief the distributive law for natural numbers states that: Let $a$,$b$,$c$ naturals then $a \cdot (b+c) = a\cdot b + a\cdot c$ And this could be generalized by induction: Let $a, a_1, a_2, \ldots a_n$ naturals then $a\cdot (a_1 + a_2 + \ldots +a_n) = a \cdot a_1 + a\cdot a_2 + \ldots +a\cdot a_n$ Those are valid propierties  with other objects, for example, integers, real numbers, complex numbers, matrices, functions, etc.  because their definition is based on this. But what happens when $n$ is not a fixed natural but a variable? I'm interested in this because I want to know if the following is valid: Let $N$ be a natural number, then: $$ N = \overbrace{1+1+\ldots +1}^{N- times}$$ and multiplying by N on the left in both sides of the equality we get $$ N\cdot N = N \cdot(\overbrace{1+1+\ldots +1}^{N- times}) $$ now the left hand side becomes $N^2$ and until this point I agree this is valid. But I'm not sure that $N \cdot(\overbrace{1+1+\ldots +1}^{N- times}) = \overbrace{N + N + \ldots + N}^{N- times}$ becasue this will bring a contradiction if we think this as a function. $$N^2 = \overbrace{N + N + \ldots + N}^{N- times}$$ and derive both side with respect to N $$ \frac{d}{dN}(N^2) = \frac{d}{dN}\left((\overbrace{N + N + \ldots + N}^{N- times})\right) \\ 2N = \overbrace{1 + 1 + \ldots + 1}^{N-times} = N$$ And clearly the function $N$ is not equal to the function $2N$, hence a contradiction I'm sure that the distributive law is failing with the derivative operator, but I'm not sure with the multiplication operator. Being more specific: if $c$ is a constant and $v$ a variable is the following assertion valid? $$\overbrace{ c + c +c \ldots +c }^{v -\text{times}} =^{?} c \cdot(\overbrace{1+1+\cdot+1}^{ v-\text{times}}) $$ EDIT Because some users identified this as a possible duplicate of: . I want to add more information to explain why that does not answer my question. My current question is not about the derivative or why the proof fails, that is well answered there. My query is, as stated in the title, about the validity of distributive law when the amount of terms are variables.  Another example: Let  $n$ be a constant  thus $$ \sum_{k=0}^{n} 2^k = 2^0+2^1+...+2^n$$ (the upper n-times brace is obviated here) but if $n$ is a variable we could tend to infinity but this may cause trouble when trying to apply the basic arithmetic law: $$\sum_{k=0}^{\infty} 2^k = 2^0+2^1+2^2+... \\  = 1 + 2 \cdot (2^0 + 2^1 + 2^2+ \ldots ) \text{(Distributive law when $n$ variable tend to infinity)} \\ = 1 + 2 \cdot \sum_{k=1}^{n} 2^k   $$ But this is absurd because if the identity holds then: $$\sum_{k=0}^{\infty} 2^k = -1$$ The sum of only positive numbers being a negative number. So we cannot apply freely the basic properties of numbers when they are variable because that variable may behave like infinity. EDIT 2 Well, I will be the most specific I could reach here and if this doesn't have an answer I give up. Let $a$ be a number and $\{a_j\}_{ j\in J}$  an indexed collection of numbers. Then $$ a \cdot \sum_{j\in J}a_j = \sum_{j\in J}a\cdot a_j$$ if $J$ is finite. That's for sure, we begin with the (I think axiom) distributive law for naturals. But what if J is not finite. ie. be infinity but numerable or infinity but not numerable. This property still holds?  If so why? because the generalization of induction uses a set not finite but numerable. So it may not work when the set of index is not finite and not numerable.

Consider the following:   $1 = 1^2$ $2 + 2 = 2^2$ $3 + 3 + 3 = 3^2$   Therefore,   $\underbrace{x + x + x + \ldots + x}_{x \textrm{ times}}= x^2$   Take the derivative of lhs and rhs and we get:   $\underbrace{1 + 1 + 1 + \ldots + 1}_{x \textrm{ times}} = 2x$   Which simplifies to:   $x = 2x$   and hence    $1 = 2$.     Clearly something is wrong but I am unable pinpoint my mistake.


We are using ffmpeg in nginx-rtmp server. And wanted to add logo and scrolling text on live streams. Example video -   These scrolls are applied with OBS studio. We want move this process to server side where we can send a plain feed to server and ffmpeg can apply text scrolling and logo on fly. Can we do this with ffmpeg or any other server side tool OBS studio cli mybe, if yes how?

I have a photo and a text page. I want to make a video with a background image that I have and the text will run on that photo. Please help me with ffmpeg


Look at these two files:       They look to me entirely identical, but File 1 has 41 bytes and File 2 has 44 bytes.  Now, I would not care about 3 extra chars, however, I think these chars are also responsible to a strange error: when I clone and run these files, File 1 runs OK while File 2 returns an error on line 3: "./BasicCheck.sh: line 3: cd: case0 : No such file or directory".  So: what are these extra chars? Why do they cause errors? And what should I do to fix these errors?  My guess is that they are newlines - perhaps File 1 has Linux-based newlines and File 2 has Windows-based newlines. Is it correct? And why should it cause such errors?

I've created a bash script but when I try to execute it, I get   #!/bin/bash no such file or directory   I need to run the command: bash script.sh for it to work.  How can I fix this?


I'm trying to compare my model results with an experiment. I want to overlap the model curve with experiment curve from a paper.   What are my options for digitizing the graph from an image in the pdf paper to excel data?

Anybody have any experience with software (preferably free, preferably open source) that will take an image of data plotted on cartesian coordinates (a standard, everyday plot) and extract the coordinates of the points plotted on the graph?  Essentially, this is a data-mining problem and a reverse data-visualization problem.


I trying to deploy my package while validating changes salesforce given this error "Lightning Page Property 'itemInstances' not valid in version 47.0" do you guys have any insight for these king of errors. Please share if you got any solution for these. Thanks in advance.

When trying to deploy the converted metadata using VS code sfdx force:mdapi:deploy deploy to my Production Org and I get the error Property 'itemInstances' not valid in version 48.0 and Property 'processOrder' not valid in version 48.0. But when I go to Developer Console and open a class, even though it says 48.0, I have the option to select 49.0, so I am assuming I have 49.0. Yet I get this error. Pretty much all my classes, trigger and components are version 48.0, but I am not sure how that affects flexipages and Approval processes.


I am trying to change the value of an input field after the user clicks on a button. It changes the value to false, but it doesn't seem like it actually "refreshes" when calling the .val() again. Here's a JS Fiddle example:  As you can see, the alert shows that the value is true, and then it shows that it's false, but then it doesn't show that it's true any time after that anymore.   $("#filter_assessment_list").click(function(){   upcoming_assessments = $("#upcoming_assessments").val()   alert(upcoming_assessments)   if(upcoming_assessments){     $("#upcoming_assessments").val(false)   }   else{     $("#upcoming_assessments").val(true)   } }) <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <a class="btn btn-sm btn-primary text-white" id="filter_assessment_list" href="javascript:;">         Show only upcoming assessments </a>  <input type="hidden" name="upcoming_assessments" id="upcoming_assessments" value="true">

Can I convert a string representing a boolean value (e.g., 'true', 'false') into a intrinsic type in JavaScript?  I have a hidden form in HTML that is updated based upon a user's selection within a list. This form contains some fields which represent boolean values and are dynamically populated with an intrinsic boolean value. However, once this value is placed into the hidden input field it becomes a string.  The only way I could find to determine the field's boolean value, once it was converted into a string, was to depend upon the literal value of its string representation.  var myValue = document.myForm.IS_TRUE.value; var isTrueSet = myValue == 'true';   Is there a better way to accomplish this?


What is the minimum value of this expression?   $$\sin^2\theta+\cos^2\theta+\csc^2\theta+\sec^2\theta+\tan^2\theta+\cot^2 \theta$$   I tried grouping $\sin^2x+\csc^2x$, $\cos^2x+\sec^2x$ and $\cot^2x+\tan^2x$.  I got the answer as $6$ but the book says $7$. How?

Find the minimum value of      $\sin^{2} \theta +\cos^{2} \theta+\sec^{2} \theta+\csc^{2} \theta+\tan^{2} \theta+\cot^{2} \theta$   $a.)\ 1 \ \ \ \ \ \ \ \ \ \ \ \ b.)\ 3 \\ c.)\ 5 \ \ \ \ \ \ \ \ \ \ \ \ d.)\ 7 $  $\sin^{2} \theta +\cos^{2} \theta+\sec^{2} \theta+\csc^{2} \theta+\tan^{2} \theta+\cot^{2} \theta \\  =\sin^{2} \theta +\dfrac{1}{\sin^{2} \theta }+\cos^{2} \theta+\dfrac{1}{\cos^{2} \theta }+\tan^{2} \theta+\dfrac{1}{\tan^{2} \theta } \\ \color{blue}{\text{By using the AM-GM inequlity}} \\ \color{blue}{x+\dfrac{1}{x} \geq 2} \\  =2+2+2=6 $  Which is not in options.  But I am not sure if I can use that $ AM-GM$ inequality in this case.  I look for a short and simple way .  I have studied maths upnto $12$th grade .


How do I prove that iteration $x_{n+1}=\cos x_n$ converges for any $x_0\in \Bbb R$ ?

Possible Duplicate:         Does the following limit exist?  $$\lim_{n\to\infty}\underset{n}{\underbrace{\cos(\cos(...\cos x))}}$$  If yes, find the limit.  If no, please explain why the limit doesn't exist.  I think, the limit exists.  So, I tried to use Squeeze theorem but didn't work.


For example :   I have a private enum in my class, like this:    private enum MyEnum {    A(x,y),   B(x,y);      private final String x;     private final String y;      MyEnum(String x, String y) {         this.x= x;         this.y= y;     }      public String getX() {         return x;     }      public String getY() {         return y;     }  }   I want to use this type in test class, without redefining it again.  Also, I want to keep minimum visibility.

How do I unit test (using xUnit) a class that has internal private methods, fields or nested classes? Or a function that is made private by having  (static in C/C++) or is in a private () namespace?  It seems bad to change the access modifier for a method or function just to be able to run a test.


Let's suppose that $(f_n)_{n}$ is a sequence of continuous functions that converges pointwise to a continuous function $f(x)$ on a closed interval $[a, b]$. Is then the convergence uniform, too?  If it is so, how do you prove it? If it isn't, could you give a counterexample, please?    My attempt  I managed to write down the hypothesis in symbolical terms, but could not go beyond that:   continuity of the sequence  ($x_0\in[a, b]$):   $\forall n, \ \forall \epsilon >0 \ \ \exists \delta>0 \  : \ |x-x_0|<\delta \Rightarrow |f_n(x)-f_n(x_0)|<\epsilon $   continuity of the limit function ($x_0\in[a, b]$):   $\forall \epsilon >0 \ \ \exists \delta>0 \  : \ |x-x_0|<\delta \Rightarrow |f(x)-f(x_0)|<\epsilon $   pointwise convergence:   $\forall x\in[a, b], \ \forall \epsilon >0 \ \ \exists n_\epsilon>0 \  : \ n\geq n_\epsilon \Rightarrow |f_n(x)-f(x)|<\epsilon $  The thesis should be:  $\forall \epsilon >0 \ \ \exists n_\epsilon>0 \  : \ n\geq n_\epsilon \Rightarrow |f_n(x)-f(x)|<\epsilon \ \ \forall x\in[a, b]$    Note  Please do not bring sequences such as that of $x^n (x\geq 0)$ as a counterexample, because they are not counterexamples:  $\text{for  } n \rightarrow \infty , \ x^n \rightarrow f(x)= \begin{cases} 0 & \text{if  } 0 \leq x<1 \cr 1 & \text{if  } x=1 \end{cases}$  so there is a pointwise convergence to $f(x)$ on $[0, 1]$; but $f(x)$ - the limit function - is not continuous, then this example lacks the conditions for the theorem to be applied.

Let $K$ be a compact metric space. Let $\{f_n\}_{n=1}^\infty$ be a sequence of continuous functions on $K$ such that $f_n$ converges to a function $f$ pointwise on $K$.   on Walt. Rudin's book Principles of mathematical analysis, 7.13, if we assume   (1). $f$ is continuous;   (2). $f_n(x)\geq f_{n+1}(x)$ for all $x\in K$ and all $n$;   then it is proved that $f_n$ converges to $f$ uniformly on $K$.   Is there counterexample satisfying (1) but not (2)? And satisfying (2) but not (1)?


Let $X$, $Y$ be independent random variables with the same geometric distribution $\{q^kp\}$. Now let $U$ be the smaller of $X$ and $Y$, and put $V = X - Y$. Show that $U$ and $V$ are independent. This is what I have thus far: We just need to show that $P(U = u)P(V = v) = P(U = u, V = v)$. Let us first suppose that $X = Y$. Then, $V = 0$ and since it doesn't depend on $X$ and $Y$ specifically, we conclude that $P(U = u)P(V = v) = P(U = u, V = v)$ holds trivially. Now let's suppose $X \neq Y$. We first calculate the probability that $X$ is the smaller one. We notice that $P(X<Y) + P(X = Y) + P(X> Y) = 1$ and that $P(X<Y)  = P(Y > X)$. Computing $P(X = Y)$ gives $\sum_{i = 1}^\infty q^{2i - 2}p^2 = \frac{p^2}{1 - q^2}$ so that $P(X>Y) = P(X<Y) = \frac{1 - q^2 - p^2}{2(1-q^2)}$. Thus if we suppose that $U = X = u$ then $V = v$ happens with a probability of $q^{v - u - 1}p$ for $V< X$ (since $Y$ takes on positive integers) and $0$ otherwise. Thus \begin{equation}        P(U = u, V = v) =\begin{cases}        \frac{1 - q^2 - p^2}{1 - q^2}q^{v - u - 1}p & \text{ if } V< X\\        0 & \text{ otherwise}        \end{cases}    \end{equation} We now note that $P(U= u) = 2q^{u-1}p\sum_{k = u+1}^\infty q^{k-1}p + (q^{k-1}p)^2 = \frac{2q^{2u-1}p^2}{1 - q} + q^{2k - 2}p^2$. On the other hand, $P(V = v) = \sum_{i \geq  -v}^\infty q^{i-1}p (q^{i-v-1}p) = \frac{p^2q^{-v}}{1 - q^2}$ I'm very confused as to what to do next since $P(U = u)P(V = v)$ and $P(U = u, V = v)$ look totally different.

THE PROBLEM :     Let $X$ and $Y$ be independent and geometrically distributed with parameter $p$. Prove that $U=\min\{X,Y\}$ and $V=X-Y$ are independent. (This property characterizes geometric distributions.)   What I did was a brute-force computation of $P(U \leq u) \times P(V\leq v)$ which came out to be $$(1-q^u) \times \left(1-\frac{q^{v+1}}{1+q}\right)$$  However, computation of $P(U \leq u, V\leq v)$ is messier with lot of cases depending on the values of $u$ and $v$. I cannot get to the end. Is there any clever, nice way to solve the problem (without getting into messy calculations)? Thanks in advance.


Show that the locus of the charge in a uniform magnetic field is a circle (in the plane perpendicular to the magnetic field). Assume the charge has initial velocity vector perpendicular to the magnetic field.  By Lorentz Force Law, we have $\vec{F}=q\;\vec{v}\times\vec{B}$, where $\vec{F}$ is the magnetic force on the charge, $q$ is the charge, $\vec{v}$ is the velocity vector of the charge, and $\vec{B}$ is the magnetic field vector. First, I chose the plane that is perpendicular to magnetic field to be the $xy$-plane, and $z$-axis is chosen such that the magnetic field is in the negative $z$ direction. Rewriting the relation: $$m\vec{a}= qB<v_y,-v_x,0>, $$where $v_x$ and $ v_y$ are the velocity components in $x$ and $y$ directions. Then, we get three differential equations. Let $\vec{r}$ be the position vector of the charge, and $k=\frac{qB}{m}$: \begin{align*} \frac{d^2{r_x}}{dt^2}&=kv_y,\\ \frac{d^2{r_y}}{dt^2}&=-kv_x,\\ \frac{d^2{r_z}}{dt^2}&=0. \end{align*} I chose the initial position of the charge to be $\vec{r}(0)=\vec{0}$. But I am stuck here, because I have no idea how to relate $v_x$, and $v_y$. Can I do things like: $$r_x(t)=r(t)cos(\phi(t))?$$ Could someone lead me a help, a small hint is enough? Thank you.

When an electron moves in uniform external magnetic field, with velocity not perpendicular, I understand that the magnitude of force is only due to the perpendicular component of velocity and is perpendicular to both components of velocity. But this force, though only due to the perpendicular component, acts on the particle. So why is it that the parallel component of velocity is not changed whereas the perpendicular component of velocity keeps changing its direction.   Is there a way to prove that its path is helical, using only vectors, and to show that it does not affect the parallel component? I've tried looking everywhere but haven't found any proof using vectors.


I am preparing a report on my research to be sent to my group, however, I don't want the reader to select the text and content, copy the code listings, etc.  Is there any package or options to do so?

Is it possible to produce a PDF with un-copyable text? I mean, when you want to copy text from the PDF, you can't copy it or what you copy is nonsense characters.


If I am upvoted, +10 (or +5) appears in the top bar. But when I am downvoted, nothing notifies me except rep changes.And if I am on another SE site, I won't know that I got downvoted until I view my profile on that site. Why is it designed so?

When you get reputation, you get a +X green spot on your reputation feed telling you that you gained reputation and if you drop down the menu, you get more detail.  How about we make it that when you lose more than you got since the last time you checked, you see it red with a little -X.  For example, let's say you've just looked at the reputation bar so any old rep notification is gone and you ask a new question. 3 users downvote your question and 1 upvotes it. You will see it green because you gained 5 rep but you should see it red because you are at -1 rep.   This would help people improve their questions / answer by seeing, as soon as they get on the site, that they got negative feedback and that something needs to be checked / changed.    It shows here so it could very well be applied to the notification count:


I know how to get the number of derangements for a word that has no repeating letters for example "guitar":  $$6!\left(\frac{1}{0!}-\frac{1}{1!}+\frac{1}{2!}-\frac{1}{3!}+\frac{1}{4!}-\frac{1}{5!}+\frac{1}{6!}\right)$$  I also know how to get the number of derangements of a word with one set of repeating letters, such as "bottle", as this has been answered in another post.    However, when there are MULTIPLE sets of repeating letters, as in "MATHEMATICAL" (2 M's, 2 T's, and 3 A's), it becomes a bit more complicated considering if the first M is in the second M's place, according to the formula it's a derangement, but it actually is not. Could anyone help me out with this? Thanks!

I am wondering how to calculate the number of derangements for the word BOTTLE. I understand how to actually do the formula for derangements already. My issue is what do you do with repeated letters. Obviously, I will be over counting if I do the typical formula. Makes me think it is the number of derangements with the letter T in their original space, but I am not sure. Can anyone help, as I am wondering if I am supposed to use PIE to solve this. Thanks.


I tried the $2D$ case with $x,y \in (0,1)$ and $P(x+y < 1) = \frac{1}{2}$  I got this by sketching the inequalities in the question, namely $ 0\leq x,y\leq 1,  $ and $y < 1-x$ and seeing that the region that fits the criteria is only half the region allowed to make a choice from. I'm thinking of extending this to $3$ numbers chosen at random between $0$ and $1$, I'd get the inequalities $ 0 \leq x,y,z \leq 1 $ and $ z < 1-x-y $. The former of the inequalities represents a unit cube and the latter is some plane that chops the cube up, so the probability is probably the volume of the allowed region divided by the volume of the unit cube. The problem arises when I try to calculate the volume of the allowed region, I don't know how to set up the integrals that define that region. For the $2D$ case it was simply $$ A = \int_0^1 1-x\,dx = \frac{1}{2} $$ I can't come up with the integrals for the $3D$ case though. I've been told before the answer has something to do with the volume of a $3$ dimensional simplex and that it'd be $\frac{1}{3!}$ but I can't derive how. I think what I need to understand is how to set up the integrals defining a region like that  In general, if you have $ 0\leq x_0,x_1, \cdots,x_n \leq 1$ and $$x_n < 1 -\sum_{i=0}^{n-1} x_i $$ How do you set up the integrals that calculate the $nD$ volume of the region allowed by these inequalities? Could anyone please explain the thought process behind that I'm only aware of the $2D$ case

Let $T_n=\{x_i\ge0:x_1+\cdots+x_n\le1\}$. I know $T_n$ is tetrahedron.  My question: How can I compute the volume of $T_n$ for every $n$?


I am facing null pointer exception on driver.get(URL) while running the code.I am using Selenium 3 with TestNG.Here, I am trying to verify URL using Assert.Please help with some solutions.  import org.testng.Assert; import org.testng.annotations.Test; import org.testng.annotations.BeforeClass; import static org.testng.Assert.assertEquals; import org.openqa.selenium.By; import org.openqa.selenium.WebDriver; import org.openqa.selenium.chrome.ChromeDriver; import org.testng.annotations.BeforeClass; import org.testng.annotations.Test;  public class WithTestNG  { WebDriver driver;  @BeforeClass public void StartBrowser() { System.setProperty("webdriver.chrome.driver","C:\\Users\\Test\\Downloads\\ch romedriver_win32\\chromedriver.exe" ); driver.manage().window().maximize(); }  @Test public void OpenStore() { String URL = "https://www.facebook.com"; driver.get(URL);  String Actual_URL = driver.getCurrentUrl(); String Expected_URL = "https://www.facebook.com/"; Assert.assertEquals(Actual_URL, Expected_URL, "URL doesn't match"); System.out.println("URL verified");  }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


If G is a group of even order, prove it has an element $a \neq e$ satisfying $a^2 = e$.  My proof:  Let $|G| = 2n$. Since G is finite, there exists, $a \in G$ such that $a^p = e$ and by Lagrange's Theorem, p divides 2n. By Euclid's lemma, since p does not divide 2, p divides n. Let $n = pk$. Hence, $(a^n)^2 = (a^{pk})^2 = ((a^p)^k)^2 = (e^k)^2 = e$. Therefore, $a^n$ is an element that satisfy the condition. Is my solution OK?  For this problem, I am just wondering how I can solve this problem without using Lagrange's Theorem, as this problem is an exercise before the Lagrange's Theorem was taught.

I am working on the following problem from group theory:     If $G$ is a group of order $2n$, show that the number of elements of $G$ of order $2$ is odd.   That is, for some integer $k$, there are $2k+1$ elements $a$ such that $a \in G,\;\; a*a = e$, where $e$ is the identity element of $G$.


Finally found a way to a new table-row with jQuery but I don't know how I can remove the same table-row with a button click.  I have tried using this code but nothing happens.    $(document).ready(function() {     $("#btnAdd").click(function() {       $("table").append(         "
<input type='list' class='form-control'></input>	<button type='button' class='btn btn-info btn-rounded btn-sm my-0'>Omhoog</button>	<button type='button' class='btn btn-info btn-rounded btn-sm my-0'>Omlaag</button>	<button></button><button id='btnRemove2' type='button' class='btn btn-danger btn-rounded btn-sm my-0'>Verwijder</button>
"       );     });     $("#btnRemove").click(function() {       $("#tr1").remove();     });     $("#btnRemove2").click(function() {       $("#tr2").remove();     });   });   I wish to remove tr2 when clicking the button with id='btnRemove2' but when I click remove button nothing happens.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Can someone tell me if this scenario is a bad idea and if so, why?  I am collecting an image from a video stream once every second to use as an icon on a webpage to let users select which live video stream they would like to view. This image is getting stored repetitively in the database.  Would it be better to write and overwrite these images to a system file and select them from that location?  I am using SQL Server 2014 and my thought is that this technique may cause problems with the Log File...  Any suggestions would be appreciated.  Thanks!

So I'm using an app that stores images heavily in the DB. What's your outlook on this? I'm more of a type to store the location in the filesystem, than store it directly in the DB.  What do you think are the pros/cons?


If $a \equiv b \mod (nm)$, then is it always true that $$a \equiv b \mod n$$ $$a \equiv b \mod m$$  I feel like it's kind of obvious because if $a-b = k_1nm$, then $a-b = k_2n$, ($k_2 = k_1n$) but I can't find any resources on the topic, so maybe I'm wrong

I noticed relation between modulo operation and number which is power of two  Example I have to calculate $ 3431242341 \mod 2^5 $, which is $ 5 $ but it is equivalent to  $ ( 3431242341 \mod 2^9 ) \mod 2^5 $   I tried many examples and it seems to be true in general, and I am not sure if it is a coincidence or true in general that I can use first modulo operation ( greater number) and the result will be the same.


I am new with VBA My worksheet works as normal with the command button. When i tried to protect my worksheet, right click on the worksheet tab and selected protect sheet with password. Once i completed it, i generated my command button in the worksheet, it showed error as below  I did not use any code for protection but right click on the worksheet and clicked on protect sheet. It worked to other sheets except the sheet I am using command button. The code I used for the command button works well when the worksheet is not protected as below. Sub Hide_Unhide()      If Range("A4").Value = "Yes" Then         Rows("4:4").EntireRow.Hidden = True     Else         Rows("4:4").EntireRow.Hidden = False     End If          If Range("A5").Value = "Yes" Then         Rows("5:5").EntireRow.Hidden = True     Else         Rows("5:5").EntireRow.Hidden = False     End If      End Sub

The code snippet below changes the data validation state of a cell and runs when the Excel-2003 worksheet is unprotected. However, when I protect the work sheet the macro doesn't run and raises a run-time error     Run-time error '-2147417848 (80010108)':      Method 'Add' of object 'Validation' failed   I have tried wrapping the code with   Me.unprotect ... Me.protect   But this does not work properly.  So, how can I modify the code below to work (ie have the code modify the unlocked cell's validation) when the sheet is protected without the above run-time error?  Update  My original work book is an Excel 2003. I tested @ solution in Excel 2007 with the following definition for Workbook_Open  Sub WorkBook_Open()     Me.Worksheets("MainTable").Protect  contents:=True, userinterfaceonly:=True  End Sub   The code still fails with the following run-time error when the worksheet is protected     Run-time error '1004':   Application-defined or object-defined error   Thanks, Azim    Code Snippet  'cell to add drop down validation list' dim myNamedRange as String dim modifyCell as Range  modifyCell = ActiveCell.Offset(0,1)    ' set list values based on some conditions not defined for brevitity' If myCondition then    myNamedRange = "range1" Else    myNamedRange = "range2" End If  With modifyCell.Validation    .Delete     'Run time error occurs on the next line'    .Add Type:=xlValidateList, AlertStyle:=xlValidAltertStop, _         Operator:=xlBetween, Formula1:="=" & myNamedRange     ...     ' skipping more property setting code '    ... End With


This question is going to be a bit more vague than I usually ask on StackExchange sites, but it keeps coming up in my life so I'm going to ask it.  Suppose I have a dataset of N datapoints that are each a vector of K values. Then for each pair of columns of the data I compute some association measure like correlation, and for every pair whose association measure exceeds some threshold I declare, "These fields are associated---something's going on here!"  Then somebody will ask "How big is K?" and I'll say, "K=100,000" and they'll dismiss the correlations as merely a result of "data dredging".  But if I'm making far fewer comparisons (say K=10) then people will be less likely to level that charge against my findings.  So my question is this: why are correlations acceptable in the small but not in the large? Why are the comparisons considered less valid when there are more of them? Shouldn't our inability to trust large numbers of comparisons mean we also shouldn't trust small numbers of comparisons?

I have several hundred measurements. Now, I am considering utilizing some kind of software to correlate every measure with every measure. This means that there are thousands of correlations. Among these there should (statistically) be a high correlation, even if the data is completely random (each measure has only about 100 datapoints).  When I find a correlation, how do I include the information about how hard I looked for a correlation, into it?   I am not at a high level in statistics, so please bear with me.


Can we convert a hex string to a byte array using a built-in function in C# or do I have to make a custom method for this?

How can you convert a byte array to a hexadecimal string, and vice versa?


I want to know the array representaion of this code,   int []x[]={{1,2},{3,4,5},{6,7,8,9}};   The program is:   class Testsss   {     public static void main(String[] args)      {        int []x[]={{1,2},{3,4,5},{6,7,8,9}};        int [][]y=x;        System.out.println(y[2][1]);     }   }   Output is 7, as I executed. How can the values are represented in array form.

In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the  of the array, as defined by Object.toString():  int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray);     // prints something like '[I@3343c8b3'   But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:  // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; //output: [1, 2, 3, 4, 5]  // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; //output: [John, Mary, Bob]


Start with a base system.   apt-get install apache2   That results in it installing the package AND starting the service.  Is there some mechanism (standard across other packages as well if possible) to request that it NOT just arbitrarily start the service before it's even been properly configured?   There are multiple reasons for this, one example is if I'm installing a service in preparation to replace an equivalent service on the box - I certainly wouldn't want it trying to start in that case, but in general, just because I've requested a package be installed, doesn't mean I want it running/started automatically.   I realize I can issue update-rc.d afterwards, but the service has already been launched (or attempted to launch) at that point.  This question should be general, but I am in particular interested for Ubuntu 14.04 LTS.

As you're probably aware, by default when you install a package on a Debian or Ubuntu based system, if the package contains a service, that service will generally be enabled and started automatically when you install the package.  This is a problem for me.  I've found myself needing to manage templates for building LXC containers. There are several containers, each corresponding to a Debian or Ubuntu release. (There are also Red Hat-based containers, but they aren't relevant here.)  /var/lib/libvirt/filesystems/debian6_template /var/lib/libvirt/filesystems/debian7_template /var/lib/libvirt/filesystems/ubuntu1004_template /var/lib/libvirt/filesystems/ubuntu1204_template   Occasionally I will find that the templates have a missing package or need some other change, so I will chroot into them to install the package. Unfortunately when I do that, I wind up with several copies of the package's service running!  By way of example, I found the templates didn't have a syslog daemon, so I installed one:  for template in /var/lib/libvirt/filesystems/{debian,ubuntu}*_template; do     chroot $template apt-get install rsyslog done   And promptly wound up with four copies of rsyslog running. Not to mention two copies of exim4. Oops!    I read somewhere (though I can't find it again now) that it's not supposed to start services when running in a chroot, but that clearly isn't happening here.  One potentially viable  calls for temporarily replacing the various commands which actually start services, such as start-stop-daemon and initctl, though this is a lot more work than I really wanted to do. If I have no other choice, though...  The ideal solution here would be for Debian-based systems to stop doing this crap, but failing that, perhaps an obscure or undocumented command line option for apt-get?  In case it wasn't clear, I really want to keep anything related to managing the templates outside the templates, if possible.


I'm interested in a Dell machine with Ubuntu pre-installed (just for the sake of knowing it's 100% Linux compatible)  The Ubuntu that's being installed on Precision and XPS13 models, is that a stock Ubuntu or did Dell add some specific things to make it work with their hardware?  If i wanted to switch to Fedora or Elementary and then back to Ubuntu at some point in the future, it would be reassuring to know that a stock Ubuntu would just work without major tweaking.

Is Dell pre-installed Ubuntu the same as the general release? Or does the Dell pre-installed version have special Dell drivers etc?  I bought a Dell XPS 9730 with 16.04 which I replaced with 18.04. It is working fine (except suspend-on-close doesn't really suspend but that seems to be a known problem). I am just wondering if I need to look out for a Dell-special 18.04 when Dell finally start shipping it, or do they just ship the standard version of Ubuntu? (The XPS 13 is one of Dell's "Canonical approved" machines.)  Output of fdisk -l (all the 'loop's are snap apps but each app appears twice in lsblk, but that is the subject of another Question!):     Disk /dev/loop0: 3.7 MiB, 3813376 bytes, 7448 sectors Units: sectors   of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512   bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop1: 86.6 MiB, 90812416 bytes, 177368 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop2: 21 MiB, 22003712 bytes, 42976 sectors Units: sectors   of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512   bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop3: 12.2 MiB, 12804096 bytes, 25008 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop4: 140 MiB, 146841600 bytes, 286800 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop5: 2.3 MiB, 2428928 bytes, 4744 sectors Units: sectors   of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512   bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop6: 140 MiB, 146841600 bytes, 286800 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop7: 86.6 MiB, 90759168 bytes, 177264 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/nvme0n1: 953.9 GiB, 1024209543168 bytes, 2000409264 sectors   Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical):   512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512   bytes Disklabel type: gpt Disk identifier:   81530E63-3D66-4216-8090-8DA401ADA1B5      Device           Start        End    Sectors   Size Type   /dev/nvme0n1p1    2048    1050623    1048576   512M EFI System   /dev/nvme0n1p2 1050624 2000408575 1999357952 953.4G Linux filesystem      Disk /dev/loop8: 1.6 MiB, 1691648 bytes, 3304 sectors Units: sectors   of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512   bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop9: 13 MiB, 13594624 bytes, 26552 sectors Units: sectors   of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512   bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop10: 86.6 MiB, 90828800 bytes, 177400 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop11: 3.3 MiB, 3411968 bytes, 6664 sectors Units: sectors   of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512   bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop12: 139.5 MiB, 146276352 bytes, 285696 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes      Disk /dev/loop13: 21.6 MiB, 22609920 bytes, 44160 sectors Units:   sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512   bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes


I have a confusion with the perception skill:  We are in a dungeon, my rogue wood elf character is walking straight while looking for everything suspicious, like traps or anything. Should I roll for perception, or for passive perception?  I am asking this because my DM keeps telling me that it is for passive perception. However, I think its for perception because I am doing the action, and not just walking by distracted.

So, I'm trying to figure out how to run the scene from the beginning of Lost Mine of Phandelver (5e starter set) where the party is ambushed by goblins and I'm really confused as to how Passive Wisdom (Perception) works.  The included rulebook mentions on page 6 :     When you hide, there’s a chance someone will notice you even if they aren’t searching. To determine whether such a creature notices you, the DM compares your Dexterity (Stealth) check with that creature’s passive Wisdom (Perception) score, which equals 10 + the creature’s Wisdom modifier, as well as any other bonuses or penalties. If the creature has advantage, add 5. For disadvantage, subtract 5. For example, if a 1st-level character (with a proficiency bonus of +2) has a Wisdom of 15 (a +2 modifier) and proficiency in Perception, he or she has a passive Wisdom (Perception) of 14.   So the party is being ambushed by goblins and at that point the DM guide mentions on page 7 :     Check to see who, if anyone, is surprised. [...] Make a Dexterity (Stealth) check for the goblins, rolling once for all of them. Roll a d20, add the goblins' Stealth skill modifier (+6) to the roll and compare the result to the characters' Passive Wisdom (Perception) scores.   So to me this reads like I should roll 1d20+6 for the goblins and compare that to the static Passive Wisdom (Perception) score on the character sheet of a PC. The PCs don't get to roll anything as they're not actively looking for enemies, even though they are investigating the dead horses.  I would also think that if the characters were supposed to roll, the DM guide would clearly instruct so, given that this is the starter set.  However, watching  at around 8:01 I notice that the DM is explicitly asking his party for a perception roll. And the same thing happens on a couple of other videos where people are running the Lost Mine adventure. The DM always requests a roll.  So what gives? Shall I take it that the DMs ask for the roll because they consider the party to be actively seeking for hidden foes? Or am I just misreading the rulebook and the DM guide?


I have a xml file with servers in it.  <?xml version="1.0" encoding="UTF-8"?> <servers>    <server>       <location>Belgium</location>       <ip>192.168.0.1</ip>       <port>8080</port>       <crt></crt>    </server>    <server>       <location>Fhoto</location>       <ip>192.168.0.5</ip>       <port>7841</port>       <crt>http://127.0.0.1/serv.crt</crt>    </server>    <server>       <location>TestingPanel</location>       <ip>192.168.1.2</ip>       <port>6969</port>       <crt>http://testingpanel.com/server.crt</crt>    </server>    <server>       <location>TestingPanel2</location>       <ip>192.168.1.3</ip>       <port>6968</port>       <crt>http://testingpanel.com/server1.crt</crt>    </server> </servers>   I made a php page that can add servers to the file and it works great. Now I want to make a form where you can enter the IP and the php script should delete the whole node.  So for example. I have a form with a textbox and I enter "192.168.0.1". I want it to delete this:     <server>       <location>Belgium</location>       <ip>192.168.0.1</ip>       <port>8080</port>       <crt></crt>    </server>   I have this so far (basically nothing):  if (isset($_POST["deleteServer"])) {      //do processing }   Please guide me in the right direction as I have no idea how to do this. Thanks in advance!

I have several identical elements with different attributes that I'm accessing with SimpleXML:  <data>     <seg id="A1"/>     <seg id="A5"/>     <seg id="A12"/>     <seg id="A29"/>     <seg id="A30"/> </data>   I need to remove a specific seg element, with an id of "A12", how can I do this?  I've tried looping through the seg elements and unsetting the specific one, but this doesn't work, the elements remain.  foreach($doc->seg as $seg) {     if($seg['id'] == 'A12')     {         unset($seg);     } }


I have been trying to use Windows Phone Emulator and it complains that Hyper-V isn't there. Is Hyper-V only available on Pro versions of Windows?   I am running Windows 8.1 and I don't see it as a feature that can be turned on/off in Windows settings.

I've been following the guide linked below to enable Hyper-V in Windows 8 so that I can try out a few Linux distros without having to mess around with my UEFI bootloader on my machine, however, this option appear to be unavailable to me. Is this because I am using an OEM version of Windows 8?    According to this guide, the option to enable Hyper-V should be available in the 'Turn Windows features on or off' menu however my menu does not display this option:    I used to use Virtualbox on my Windows 7 machine but thought I had better try the built in functionality of Windows 8 so can someone confirm whether or not I need the Pro version of Windows 8 to do this as there seems to be mixed signals coming from a general Google search on the topic.


Let $V$ be a finite dimensional vector space and let $U_1, U_2, \dots, U_k$ be subspaces of $V$ such that $\dim U_1 = \dim U_2 = \dots = \dim U_k$. Gotta show that there exists a subspace $W$ of $V$ such that $$V = U_1 \oplus W = U_2 \oplus W = \dots = U_k \oplus W.$$   I let $\dim V = n$ and let $\dim U_i = m$. I then tried taking the basis of all subspaces and extended to a basis of $V$ $$u_{11},u_{21},\dots,u_{m1},u_{12},u_{22},\dots,u_{m2}, \dots, u_{1k},u_{2k},\dots,u_{mk}, x_{mk + 1}, x_{mk + 2}, \dots, x_n.$$ I then let $W = span\{u_{11} +u_{12},u_{12} + u_{13}, \dots, u_{1 (k-1)} + u_{1k}, \dots, u_{m1} + u_{m2},u_{m2} + u_{m3}, \dots, u_{m (k-1)} + u_{mk}, x_{mk + 1}, x_{mk + 2}, \dots, x_n\}$   But this would be a hassle to show it is linearly independent when doing a direct sum with any of the $U_i$'s and when showing it spans $V$.   Is my method right at all? Is there an easier way? Please, any kind of aid or hints would be greatly appreciated.

Prove the following. Let $U_1, U_2, ..., U_k$ be subspaces of finite-dimensional linear space $X$ such that  $\dim U_1=\dim U_2=\ldots=\dim U_k$  Then there is a subspace $V$ of $X$ for which  $X=U_1\oplus V=U_2\oplus V=\ldots=U_k\oplus V$  I tried the idea to show that, $V$ lies in the intersection of all of the complements of $U_i$, so $V\subset \bigcup_{i=1}^{i=k}U_i^c$, and I think that will work in case this interception is not empty. I am wondering if this is a right way, because I am stuck with proving that it's not empty, so would be thankful for any hint or direction.


I'm having a problem in my abstract class and its subclass. ActionDeck is a subclass of Deck which contains a no-argument constructor for ActionDeck, but whenever I get NullPointerException for the deque and array list instance variables my superclass has. It also marks it as unused in VScode. I'm not sure if I am implementing it correctly. What is wrong with my code? Deck.java abstract class Deck<C> {      protected Deque<C> deck;     protected ArrayList<C> temp;          public Deck () {         Deque<C> deck = new ArrayDeque<>();         ArrayList<C> temp = new ArrayList<>();       }  ActionDeck.java public class ActionDeck extends Deck<ActionCard> {      public ActionDeck() {         super();     }  So when I tried to add something into the arraylist in ActionDeck it spits out an error: Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.util.ArrayList.add(Object)" because "this.temp" is null         at ActionDeck.generateDeck(ActionDeck.java:26)         at Board.initializeData(Board.java:30)         at Main.main(Main.java:10)  Help would be appreciated, thank you!

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


In discussing geometrical optics, Fermat's principle of least time is often used to solve problems and is generally used as a replacement of laws of reflection and refraction. Fermat's principle is usually presented as an intuitive idea, but I wish to find a way where we can show that is is actually a result of least of reflection and refraction. We have explanation for laws of reflection and refraction and they must be the basic laws, with Fermat's principle being a consequence of it. Do we have any explanation suggesting that Fermat's principle is the direct consequence of laws of reflection and refraction?

whenever two media and two velocities are involved, one must follow Snell's law if one wants to take the shortest time.   Why snells law must be followed to travel diffrent media in shortest time?  Does this mean that the path followed by light in travelling through different media will give a straight line if different media are transformed into like first media? I think so because one would get shortest time if one travel in a straight line.  So how does this apply to particles? Does this statement points wave particle duality?


During the past week, I am having problems with "hash sum mismatch".  I keep getting hash sum mismatch regardless of the update source/server used.  This is involving the following:  W: Failed to fetch ... //archive.canonical.com/ubuntu/dists/trusty/partner/binary-amd64/Packages  Hash Sum mismatch W: Failed to fetch ... //archive.canonical.com/ubuntu/dists/trusty/partner/binary-i386/Packages  Hash Sum mismatch W: Failed to fetch ... //archive.ubuntu.com/ubuntu/dists/trusty-updates/main/i18n/Translation-en  Hash Sum mismatch W: Failed to fetch ... //archive.ubuntu.com/ubuntu/dists/trusty-security/universe/i18n/Translation-en  Hash Sum mismatch E: Some index files failed to download. They have been ignored, or old ones used instead.   There is a notice about checking the Internet connection.  It doesn't matter which update server I used.  I get the same results.    I have cleared out the var/lib/apt/lists and run apt-get update in the terminal but no change.  I have also a dir/file of /var/lib/apt/lists.old.  Do I or can I delete/remove this dir/file?  How can I fix it?

When I check for updates, I get a "Failed To Download Repository Information" error.   This is what comes up under details:   W: Failed to fetch gzip:/var/lib/apt/lists/partial/us.archive.ubuntu.com_ubuntu_dists_natty_main_source_Sources  Hash Sum mismatch,  E: Some index files failed to download. They have been ignored, or old ones used instead.


I seem to be running into an issue with creating new objects? Could someone please help me? The Set Up I am building a packaging mock up, that requires multiple boxes that slide together. the new object slides into / out of the old object. So Eventually these will be animated (Very New to Allot of This) The Question As per my images below, Both outer object and inner object have been set to the same size yet they visually appear two different sizes? The "Old Object" is created from the original default cube as per my memory. The second object is per a new added cube (1mm). How can I get an accurate scale? Any help on this would be much appreciated. I am learning allot of new skills with this project and very open to new avenues in thinking about 3D development. Thank you.

First time in metric system and I can't figure out what is the dimension in blender, first of all the scale of a cube is one and the dimension is 2:  scaling the edge of only one edge up in edit mode turns up the dimension of the whole object to the size of the scale of the edge, and not the object in an average:     So, I'm a bit confused, about what the dimension in blender actually refer to, and what the difference between it and scale is?     EDIT:  What if the bounding box length and the edge are of equal size:


Now i want to run android apps on my pc.I runned apps on pc by using bluestacks but i want to know any other way to run android apps on pc.Is there any alternative to this one.

Is there any method for using Android applications on a computer, because I found  tutorial but my laptop just has 1 GB of RAM and works very hard. I want to use WeChat on my PC because I like it very much.


I'm I total beginner and can't figure out what the problem is here - I want the scanner input to close after when the user enters "exit". When I try my code it says "Exit >" and I'm still able to do input. Is it something with the scope of input.close()?       String command;          do {         System.out.print("> ");         command = input.nextLine();           switch (command) {         case "register new dog":             System.out.println("You gave command: register new dog");             System.out.println("Command? ");             break;          case "increase age":             System.out.println("You gave command: increase age");             System.out.println("Command? ");             break;          case "list dogs":             System.out.println("You gave command: list dogs");             System.out.println("Command? ");             break;          case "remove dogs":             System.out.println("You gave command: remove dogs");             System.out.println("Command? ");             break;          case "exit":             System.out.println("Goodbye!");             break;          default:             System.out.println("Error: invalid command, choose again: ");             System.out.println("Register new dog");             System.out.println("Increase age");             System.out.println("List dogs");             System.out.println("Remove dogs");             System.out.println("Exit");            }      } while (command != "exit");      input.close();

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I'm missing the item after the pogo stick in the inventory although I'm already at the castle, what is it and how can I get it?

After beating the game, I still have several empty inventory spots.  I most likely missed several items in my addicted frenzy to finish the game.  What are all the items that can be found in the game? And where can they found?


I recently did a factory reset to my phone and to my surprise, the operating system remained to the last updated version (6.0.0) and not the version I had when I bought the phone (5.0.0).   Why does this happen? Doesn't a factory reset reset the operating system too?

I have a Samsung Galaxy S3 and have it updated to 4.1.2 from ICS. If I restore my phone to factory settings (either by going to settings or by rooting), will I lose my updates? If so, is there any other way to restore without having the above setbacks?


I was wondering what the difference is between these pairs of examples:   Okay, so if we are going to work where do we begin? Okay, so if we are going to work where do we start?   And   We are going to have a party tomorrow. We should start making preparations today. We are going to have a party tomorrow. We should begin making preparations today.

Today, when looking up the definitions of the phrasal verb "take sth up", I noticed that one of them was written like this: "to start or begin something such as a job." For the first time I realised that probably "start" and "begin" don't exactly mean the same thing.So the question is what the difference is between the two, and if there are cases when they mean exactly the same thing.


I'm trying to get different band names, but then i type  $Band = "Azuolas" and $Band="Ąžuolas" I gate both at the same time. how can I fix this?  $band =$_POST['band_name']; $sql= "SELECT  Band FROM Songs WHERE Band='".$band."' "; $query_run =mysqli_query($con, $sql); while($mysqli_fetch_assoc =mysqli_fetch_assoc($query_run)){ echo $mysqli_fetch_assoc['Band']."<br>"; }

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


The Problem: I have created a Codesandbox too clearly see the problem:  I basically have just a navbar with some padding, and below is the content area. I want to color the bottom like it is right now (or rather have select the full height of this bottom area, the color is for visibility and set its height to 100 %) but without producing a vertical scrollbar. I achieved the full height on the bottom area by selecting html, body and #root and set its height to 100%. This works but it gives me the scrollbar, because I think it's adding the scrollbar to it. Is there a way to avoid this or a better way using another technique? Basically: Take all available height but don't produce scrollbar Just adding a overflow: hidden works but I think if I have scrollable content on it (the page grows) it wont be displayed so thats no real resolution for this. I'm a bit rusted honestly and maybe I'm doing it completely wrong, but googling and this SO post didnt help me much unfort:  EDIT: I tried the first answer here "The flexbox way":  This works fine but when I want a container to have scrollable content inside without scrolling the whole page it doesn't work. It adds a scrollbar. I edited the example.

I am working on a web application where I want the content to fill the height of the entire screen.  The page has a header, which contains a logo, and account information. This could be an arbitrary height. I want the content div to fill the rest of the page to the bottom.  I have a header div and a content div. At the moment I am using a table for the layout like so:  CSS and HTML    #page {     height: 100%; width: 100% }  #tdcontent {     height: 100%; }  #content {     overflow: auto; /* or overflow: hidden; */ }

...

...

     The entire height of the page is filled, and no scrolling is required.  For anything inside the content div, setting top: 0; will put it right underneath the header. Sometimes the content will be a real table, with its height set to 100%. Putting header inside content will not allow this to work.  Is there a way to achieve the same effect without using the table?  Update:  Elements inside the content div will have heights set to percentages as well. So something at 100% inside the div will fill it to the bottom. As will two elements at 50%.  Update 2:  For instance, if the header takes up 20% of the screen's height, a table specified at 50% inside #content would take up 40% of the screen space. So far, wrapping the entire thing in a table is the only thing that works.


I am using a template with this preamble: \documentclass{ieeeaccess} \usepackage{cite} \usepackage{amsmath,amssymb,amsfonts} \usepackage{algorithmic} \usepackage{graphicx} \usepackage{textcomp}  I also need to add these packages: \usepackage{tikz} \usetikzlibrary{quantikz}  However there is a fatal conflict in compilation (I think between tikz and graphicx. How could I solve it?

I have been trying for a while to load the tikz package to the IEEE ACCESS template. Whenever I use the command \usepackage{tikz}, I am getting the error   /usr/local/texlive/2017/texmf-dist/tex/generic/pgf/math/pgfmathfunctions.random.code.tex, line 33 Missing number, treated as zero.   It was working fine with the IEEEtran template and I was able to draw my circuit diagrams in that.   Anyone has any idea how to solve this issue?


I submitted a paper to an editor of well-known journal via email. It has been almost a month I did not hear anything, even not an acknowledgement from the editor, though I sent them 2 follow up emails.  What should I do?

About 5 months ago I submitted a paper to a journal. The editors assigned a reviewer. In the meantime I sent a couple of revised versions, which did not help matters, but the editor ultimately wrote back and asked me to complete my revisions and re-submit the document. I did that within a couple of weeks. The editors did not acknowledge receipt of this submission, but I did not want to ask for one since I felt I had already been pestering them too much. A couple of weeks later, I notified the editors that I wanted to post a couple of graphs from the submitted paper on a blog, although I hoped to make it clear that only a very small component of the whole paper was being posted on the blog. The editors did not respond to this notification. More than two months went by after the re-submission, and I sent a message to the editor asking for a status update, just to be sure that the paper was still being considered and under review. It seemed to me that a very simple "yes, it is still being reviewed", or "no, we have considered your paper withdrawn and it is not being reviewed" or something like that, would suffice. About 10 more days passed with no response, and I thought I would telephone the editor with my question, on the off-chance that my emails were not getting through.  I left a message for him, and another week has gone by with no response. At what point do I take the non-response from the editor as a message that my paper is no longer under review and that I should re-submit it elsewhere? The journal is otherwise a reputable journal, and I would like my paper published there, but there are many others that interest me too.  I feel like I made a mess of the whole process, and am to be blamed for over-communication and confusion, but am I not owed the courtesy of a response from the editor?


How can I run a shell as Admin in Terminal if Im logged in as User with standard privileges? I know the passwords for user and admin account

I was trying to install , and I got  npm ERR! Error: EACCES, Permission denied '/usr/local/lib/node_modules' npm ERR!  npm ERR! Please use 'sudo' or log in as root to run this command. npm ERR!  npm ERR!     sudo npm "install" "." "--force" "--global" npm ERR!  npm ERR! or set the 'unsafe-perm' config var to true. npm ERR!  npm ERR!     npm config set unsafe-perm true   How can log in as a root?


There are $ 25 $ balls in a box. Some balls are red and the rest are blue. We select $ 2 $ balls in a row, one after the other. The selection happens without repositioning. We are given that the probability of choosing $ 2 $ same colored balls is equal to the probability of choosing $ 2 $ different colored balls. How many red balls are in the box? I would appreciate your guidance. Thank you very much in advance.

We have 25 stones in a bag. Some stones are black and the rest are white. We select 2 stones in a row, one after the other, without repositioning. If the probability of choosing two stones of the same color is equal to the probability of choosing two stones of different colors, find how many black stones are in the bag. I figured out this is a combinations problems with C(25,2) different pairs of stones but I face difficulty in expressing the total of different pairs of the same color stones. I would appreciate your guidance. Thank you very much in advance.


After waking my computer up from suspend, I was confronted with this:    It is reproducible, however the second time, it looked slightly different:    Notice the strange edges of all open windows, which seem to be showing the receptive area of the windows (perhaps the part that measures how close they are to other windows for snapping into place?)  Has anyone seen this before and is it a known issue, with a solution?  I haven't been able to find this problem explained anywhere else - perhaps because I don't know what to search for.  This machine has a newly installed Ubuntu 16.04 running on an Intel 6850k with an Nvidia graphics card using the driver 375 (installed via ppa).

NB: Nvidia has released an official fix; please see ,  and/or .  Upon waking up Ubuntu 16.04 from Suspend, the following graphical glitches appear around all windows, context menus, and similar:      This is currently known to affect the following NVIDIA cards running the proprietary drivers:  NVIDIA GeForce 610M, driver version 375.39, 340.102 NVIDIA GT 630M, driver version 375.39 NVIDIA GTX 650, driver version 375.39 NVIDIA GT 740M, driver version 378.13 NVIDIA GTX 745, unknown driver version NVIDIA GTX 850M, driver version 375.39, 378.13 NVIDIA GT 940M, driver version 375.39 NVIDIA GTX 950M, unknown driver version NVIDIA GTX 960M, driver version 378.13 NVIDIA GTX 970, driver version 375.39 NVIDIA GTX 970M, driver version 375.39 NVIDIA GTX 980 TI, unknown driver version NVIDIA GTX 1060, driver version 375.26, 375.39, 378.09 NVIDIA GTX 1070, driver version 378.09  The above above list has been sourced from reports from other users here on AU,  thread, and  thread. NB: This is be no means an exclusive list. It probably effects nearly all Nvidia cards.  Furthermore, this issue has been replicated on a clean install where the only change was a software update and the installation of the latest NVIDIA drivers.  What is going on, and how can it be resolved?


I have the below files in directory new:  Dec 14 04:35 New_folder Dec 13 05:50 abc.sh Dec 13 06:33 ashutosh.txt Dec 13 06:40 delete.sh Dec 13 07:19 test.bat Dec 14 04:44 test.sh Dec 14 04:30 xyz.sh   And running the below command  find /test/new/ -type f -mtime +1   According to definition of this command I will get all files which are older than one day, on 14 Dec when I am running, but I am not getting any file in the output.  What is a command line that works?

I'm struggling to wrap my mind around why the find interprets file modification times the way it does.  Specifically, I don't understand why the -mtime +1 doesn't show files less than 48 hours old.   As an example test I created three test files with different modified dates:   [root@foobox findtest]# ls -l total 0 -rw-r--r-- 1 root root 0 Sep 25 08:44 foo1 -rw-r--r-- 1 root root 0 Sep 24 08:14 foo2 -rw-r--r-- 1 root root 0 Sep 23 08:14 foo3   I then ran find with the -mtime +1 switch and got the following output:  [root@foobox findtest]# find -mtime +1 ./foo3   I then ran find with the -mmin +1440 and got the following output:   [root@foobox findtest]# find -mmin +1440 ./foo3 ./foo2   As per the man page for find, I understand that this is expected behavior:   -mtime n         File’s  data was last modified n*24 hours ago.  See the comments         for -atime to understand how rounding affects the interpretation         of file modification times.   -atime n        File  was  last  accessed n*24 hours ago.  When find figures out        how many 24-hour periods ago the file  was  last  accessed,  any        fractional part is ignored, so to match -atime +1, a file has to        have been accessed at least two days ago.   This still doesn't make sense to me though.  So if a file is 1 day, 23 hours, 59 minutes, and 59 seconds old, find -mtime +1 ignores all that and just treats it like it's 1 day, 0 hours, 0 minutes, and 0 seconds old?  In which case, it's not technically older that 1 day and ignored?   Does... not... compute.


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

I was very inspired by Michio Kaku's  on the possibilities of quantum computing and also listening to Talia Gershon's  on it.   As I come from a business & analytics background, what materials can I begin exploring to prepare to learn more about the field of quantum computing? Eg. what would I need to study to understand Peter Shor's algorithm,  on physics, etc.


This question is the inverse of: "Could an object orbit while moving at twice the speed, but at the same distance, if it had half the mass?"  I'm curious about the nature of orbits, but am not well enough versed in mathematics to understand Kepler's laws well. I have been wondering if the mass of a planet and a star it orbits could be determined based solely on the distance and speed of the orbit, or if the ability to orbit at a given speed/distance was based relatively on the mass of both objects (i.e., we could determine the ratio of the mass of the two objects, but not the actual mass).

Does the mass of both the parent object, and the child object affect the speed at which the child object orbits the parent object?  I thought it didn't (something like $T^2 \approx R^3$) until I saw an planet on the iphone exoplanet app, that is closer to it's star than a planet in another system, yet takes longer to complete one orbit. Both of the planets were a similar mass, as were the stars.


I am new to GIS application world. I would like to ask what are the other alternatives to   in the market preferably open source?

I currently know the following open source GIS servers:   : java based, vector and bitmap support, also supports. Is now on par with mapserver (performance-wise). : c/c++, used to be the fastest server. Better for raster than vector? : do not know this : the new kid on the block? do not know much about it, but it looks appealing : as far as i know, only retrieves vector-data for display in openlayers. There does exist a rails implementation.   If possible i would like some kind of comparison, which did you choose or prefer and why?  I am looking at building a rails website, and need some kind of GIS server. I will need raster and vector data (clickable). Is this doable with one server? Backend database will be Postgis.


I have built a neural network for approximating a certain function and decided on a metric how to evaluate the performance. Now, where do I start with optimizing to get the optimal result? I need to decide on number of layers, hidden neurons, learning rate, learning algorithms and all other hyperparameters. What is the usual  procedure and order in which to optimize all network's parameters? I guess I am looking for some kind of general guidelines to follow to obtain the best possible performance

I know that a neural-network architecture is mostly based on the problem itself and the types of input/output, but still - there's always a "square one" when starting to build one. So my question is - given a input dataset of MxN (M  is the number of records, N is the number of features) and a C possible output classes - is there a thumb-rule to how many layers/units should we start with?


Does there exist a ring having infinitely many zero divisors ?

Please help me to prove that if $R$ is an infinite ring, then $R$ has either an infinite number of zero divisors, or it has no zero divisors.


Creating a table in IEEE transaction format. The last cell of the table has to combine two rows. I can put the same text using the multirow package, but the horizontal separator cuts right through the text. Here is my code for the table.   \begin{table*} \centering \begin{tabular}[l]{|l|l|l|l|} \hline \textbf{Description} & \textbf{Constraints} & \textbf{Objective} &\textbf{Remarks}\\ \hline Sum rate maximisation with given sum power&$\sum_{i=1}^Kp_i$&$\sum_{i=1}^Kr_i$&Solved~\cite{Barman2014a}\\      \hline Sum power minimisation with given sum rate&$\sum_{i=1}^Kr_i$&$\sum_{i=1}^Kp_i$&Proposed here\\ \hline Weighted rate maximisation with individual power constraints&$p_i\leq p'_i\quad\forall i$&$\sum_{i=1}^Kw_ir_i$&Solved~\cite{Tse1998}\\ \hline Sum power minimisation with individual rate constraints&$r_i\leq r'_i\quad\forall i$&$\sum_{i=1}^Kp_i$&Sub-optimal solution proposed~\cite{Yu2006}\\ \hline Weighted sum power minimisation with individual rate constraints&$r_i\leq r'_i\quad\forall i$&$\sum_{i=1}^K\lambda_ip_i$&Not solved\\ \hline Weighted sum power minimisation with weighted rate constraint&$\sum_{i=1}^Kw_ir_i$&$\sum_{i=1}^K\lambda_ip_i$&\multirow{2}{*}{Standard convex problem}\\ \hline Weighted sum rate maxisation with target weighted power constraint&$\sum_{i=1}^K\lambda_ip_i$&$\sum_{i=1}^Kw_ir_i$&\\ \hline \end{tabular} \end{table*}   And here is my output table.  As you can see the problem is with the "Standard convex problem". How to make the line stop at the previous column. Also please tell me how to post a large block of code here with proper tabulation. I cannot format it correctly. Sorry for the trouble.

In a table, how can I draw a horizontal line that goes only through some of the cells? I mean a line like the one in the Foo and in the Bar area of this table:  +----+-----+ |Foo |1 |2 | |    |1 |2 | |    +--+--+ |    |1 |2 | |    |1 |2 | +----+-----+ |Bar |1 |2 | |    |1 |2 | |    +--+--+ |    |1 |2 | |    |1 |2 | +----+--+--+


I stumbled across a  on SO while looking for answers and ended up adding my own  to the list of suggested solutions. Soon after this I realized that this question was a community wiki before I had added my answer to it.  According to the community this was the best answer as it received most upvotes for the question but I received nothing for it. Why?  Questions:   Why does making a question/answer a part of the community wiki mean no one can earn points for contributing to it?  What's the reason for the reputation being disassociated with the contributor?   I understand on a technical level that the posts sort of gets owned by the community user instead of me but that shouldn't mean I get nothing for contributing should it?  Edit:   I've read the post  and I'm not concerned with what Community Wiki posts are. I'm concerned with the rep-denial aspect and the reasoning behind it.   That said Robert's answer addressed this.

Some questions and answers are marked Community Wiki and are owned by a community wiki user:  (In fact, this very question is one of them)  Why have Community Wiki posts? How do Community Wiki posts work? How does a post become a Community Wiki post? How can the Community Wiki status be removed from a post? How can I find Community Wiki posts?


I want to take pictures of moving cars/bikes so that the background is all blurred and the subject is sharp so it gives an impression of moment. Not like other pics where the subject seems stand still. BTW I shoot D7000.

In this photo nominated as , the background seems to blur while the rider is sharp. Wouldn't this normally be the other way?  How was this done?


Let $X$ be a the strong solution of the SDE on $\mathbb{R}$ $$dX_t = b(X_t)dt + \sigma(X_t)dW_t$$ $$X_0 = x$$ where $b,\sigma \colon \mathbb{R} \to \mathbb{R}$ are Lipschitz functions.  Dose the law of the random variable $X_t$ has a density w/r to the Lebesgue measure?     I tried to find the law of $X_t$ by applying Itô rule to $f(X_t)$ when $f \in C^2$ to try to find a formula for $\mathbb{E}(f(X_t))$ but I didn't get to anything nice.  Every help will be appreciated.

Suppose we have an sde of the form:  \begin{eqnarray} dX_t=b(X_t)dX_t + \sigma (X_t)dB_t \end{eqnarray} where $b$ and $\sigma$ are Lipschitz. Then we have existence and uniqueness of the solution $X_t$, which is an Ito diffusion.   When can we say that the distribution of $X_t$ for a particular t is absolutely continuous wrt Lebesgue measure (besides perhaps the initial distibution at $t=0$)?


Suppose I have private static MyClient _myClient that opens a connection to an external server. It implements IDisposable. The 'client' is created on first use:  if (_myClient == null)     _myClient = new MyClient (_myClientHostAddress);   I'm assuming once the above statement is executed the class loader puts the instance _myClient on the application stack.  Is this usage correct:  using (_myClient)   and if so what happens to _myClient when the using statement is out of scope?  Is _myClient marked for gc or popped directly off of the application stack by IDisposable?  If marked for garbage collection does the garbage collector pop it off the stack?  Thanks!

User  answered the wonderful  question by mentioning the using keyword. Can you elaborate on that? What are the uses of using?


I saw this video here    And I wanted to follow it to create my own HourBoost bot. So I purchased a £3 Ubuntu VPS from OVH and tried to follow his video directly and it doesn't work. I am beyond confused as he is using the full OS and mine is just the terminal. I am extremely new to this so I don't even know where I have gone wrong.  So far I'm here    Could anyone take the time to help me?  I don't think its that complicated considering the video is only 5 minutes.

I noticed over at the  website that node is currently at v 0.12.0.  Can someone let me know how to install the latest version of node together with npm (terminal commands please)?


In the help of the glm command in R, I read     the binomial family the links logit, probit, cauchit, (corresponding to    logistic, normal and Cauchy CDFs respectively) log and cloglog   (complementary log-log)   What are the difference between the "normal", Cauchy, log, cloglog models? When should I use them? Are these ONLY referring to different the error models? Anyone can provide Examples or recommendation to prefer one over the other?

What is the difference between  and ?  I'm more interested here in knowing when to use logistic regression, and when to use Probit.  If there is any literature which defines it using , that would be helpful as well.


I don't know if this question is trivial but let me put it in the first place.  I'm trying to find the sum of $\binom{n}{0}^2+\binom{n}{1}^2+\binom{n}{2}^2+\cdots+\binom{n}{n-1}^2+\binom{n}{n}^2$ or equivalently $\displaystyle \sum_{k=0}^n \binom{n}{k}^2$.  How would you proceed?

I was hoping to find a more "mathematical" proof, instead of proving logically $\displaystyle \sum_{k = 0}^n {n \choose k}^2= {2n \choose n}$.  I already know the logical Proof:  $${n \choose k}^2 = {n \choose k}{ n \choose n-k}$$  Hence summation can be expressed as:  $$\binom{n}{0}\binom{n}{n} + \binom{n}{1}\binom{n}{n-1} + \cdots + \binom{n}{n}\binom{n}{0}$$  One can think of it as choosing $n$ people from a group of $2n$  (imagine dividing a group of $2n$ into $2$ groups of $n$ people each. I can get $k$ people from group $1$ and another $n-k$ people from group $2$. We do this from $k = 0$ to $n$.


I am doing a multiple choice test, and they say that   $(p\oplus q)\land q$ is logically equivalent with $\neg (p \land q)$  I am confused about this, because normally I can verify with a truth trable, But I do not understand $\oplus$ could someone explain this for me?

Could someone show me the truth table for this proposition? I think I have the last two down, but I'm not sure what the symbol in the following one is: $$p\oplus (p\wedge q)$$


Is there a way to prioritize which programs are using my bandwidth? For instance I often have background downloads running when I play video games but would like to make sure Dota 2 has all the internet connection it needs. Is this possible?

Whenever my browser wants to download data, I want it to be granted as much of the bandwidth as it wants, while other applications must do with the leftover bandwidth; and when the browser is not transferring any data, other applications could be given the bandwidth. Something like the process priority in Windows task manager. Any method/software to accomplish this automatically?


I'm looking for a screenshot and upload tool similar to Gyazo and ShareX, that allows me to take screenshots of a certain area, or a whole window, etc and then gives me a link that it was uploaded to after.  Does anyone know of any decent software for this on Ubuntu 18?

I have noticed that many people use images in their Ask Ubuntu answers. What software are people using?


I was looking for an answer to this question for some days now:     Find a function f such that $f(f(x))=-x$   Please help, thank you!

Is there a function $f\colon \mathbb{R} \to\mathbb{R} $ such that $ f(f(x)) = -x$ ?


I have .java files that right now open with a default program that is notepad++, but I don't want a default program to open all my Java files, I want to choose every time.  How would I go about making it not have a default opening program?

How do you associate a specific file type to an application on a Windows (Vista) PC?


We've recently been doing a lot of work on our site's SEO (www.betterthanreviews.com). We recently did a push to update the rich snippets breadcrumb, meta description, and star rating.   After giving Google some time to index the site, it has updated the breadcrumbs and meta descriptions for our review pages, but the stars are still not showing. This is currently how it appears on a Google search (link to the actual page: http://www.betterthanreviews.com/home-security/livewatch):     This is what the Rich Snippets is supposed to look like, and how it appears in Google's testing tool:    More context: As seen in our html, we are using schema.org language. We initially were using schema.org/Corporation for the site, but we now have the page labeled as schema.org/HomeAndConstructionBusiness because Google will not show star ratings for the Corporation language. However, in our Webmaster Tools, the Structured Data is still showing the Corporation language, which could be a potential issue.  Here is a look at some of the coding that we used. But it can be looked at closer by inspecting the element:

         <meta content="4.5" itemprop="ratingValue" title="4.5 out of 5 stars" class="star-rating-readonly">            <meta content="2013-12-05" itemprop="datePublished">
Way better than my previous system

Scott H.
             •
2 months ago

I love it! The experience I have had so far is extremely positive. I had another alarm system before and I didn't like it but this one is really nice. I am telling everybody about it.

   Any suggestions for how to fix this?

I have applied structured aggregate rating to my website using Schema.org but after a couple of months the 1 to 5 rich snippets are not displaying for the given set of URLs in Google.  Here is an example URL:    To me this page should be displaying the rich snippets as I have tested it using the Google Rich snippet testing tool and it has flagged no issues.  So my question is: Is the site just not authoritative enough to display rich snippets yet (I have read that Google displays rich snippets "at discretion") or is there an error in my code that is not being picked up by the tool which is hindering the display, or something else?  UPDATE: I have updated my code according to @unor recommendation which clearly states rating only. I have introduced more fresh URL's into the Google index which already have ratings but the rich snippet is still not displaying...


I have a simple script that adds a click event listener to an element that is not currently on the screen. It works fine when I first visit a page but if I click a link to another page then come back it doesn't work, I don't get any errors in the console it just does nothing. Here is the script  $(function () {     // event listener for removing overlay and form when clicking form close button     addCloseButtonBehaviour(); });  function addCloseButtonBehaviour() {     $('body').on('click', '#close-button', function () {         $('#form-container').remove();         $('#full-screen-overlay').remove();     }); }   Can anyone tell me a way that I can do this and ensure that it works every time I visit the page? Thanks in advance everyone.

For all major browsers (except IE), the JavaScript onload event doesn’t fire when the page loads as a result of a back button operation — it only fires when the page is first loaded.  Can someone point me at some sample cross-browser code (Firefox, Opera, Safari, IE, …) that solves this problem? I’m familiar with Firefox’s pageshow event but unfortunately neither Opera nor Safari implement this.


I tried to unit and join the end anchor point with the path shown in the picture but I either get the paths interlocked or part of the drawing just disappear.

How do I get rid of these edges? I've tried the Join Tool. I've tried to highlight them with the white and the black arrow and then Object>Path>Join.  At this point I don't know what to google for, since everytime I search for a solution only the same suggestions come up, which I've tried.  Thanks


Is there a way to check if my internet connection is with a dynamic or static IP? I'm running OSX.

Maybe a stupid question but how can I tell if I have a static IP address or a dynamic IP address? Running Fedora-13


I have just started learning C from Ritchie and Kernighan's book. I am trying to reverse a string recursively, however, I get a segmentation fault with this code: #include <stdio.h> #include <string.h> void reverse (char s[], int l, int r);  int main () {       reverse("hello world", 0, 10); } void reverse (char s[], int l, int r) {           int temp = s[l];     s[l] = s[r];     s[r] = temp;          if (++l >= --r) {         return;     } else {         reverse (s, ++l, --r);     }     }  I'm not sure what im doing wrong, but I found that the segmentation fault occurs at s[l] = s[r];

The following code receives seg fault on line 2:  char *str = "string"; str[0] = 'z';  // could be also written as *str = 'z' printf("%s\n", str);   While this works perfectly well:  char str[] = "string"; str[0] = 'z'; printf("%s\n", str);   Tested with MSVC and GCC.


On a login form where the user must select the name of the store location that they are logging into, there may be up to 6000 values. For a company that only has 5-10 locations the dropdown works well.  What would be a good alternative to using a dropdown to make it usable for up to 6000 locations?

I have a field which needs to be populated from a large list of items (many thousands). These items have unique numbers as identifiers, and there can be many thousands of them. (Similar to the way that bug tracking software will label 1000 items from #1 -> #1000). The field must be populated with a valid value.   A dropdown is obviously not a suitable control here. I've thought of five possible solutions:   Free text input, with some kind of validation on input blur. As (1) but with a manual 'check' button which manually validates input instead of doing it automatically. As (1), but with a 'search' button which overlays a form allowing user to search on various item properties (ie. item title), and then select from a list of valid options? An inline sortable/filterable/pageable grid showing all items and some properties (such as identifier, Title, Date Created). As (4), but the grid is hidden by default. A 'search' button opens the grid in an overlay.    The first two options require the user to already know the ID of the item they are selecting or navigate away from the page and search for it. The inline grid might take up quite a lot of space for what is supposed to be a fairly simple selection. The overlays again seem quite complex for a simple control.  Are any of the options I've detailed appropriate? Is there a better way?


What would be the performance difference when getting result from return value and from output parameter of a function in c#?

Do out parameters in C# have any performance implications I should know about? (Like exceptions)  I mean, is it a good idea to have a method with an out parameter in a loop that will run a couple of million times a second?  I know it's ugly but I am using it the same way as Int32.TryParse is using them - returning a bool to tell if some validation was successful and having an out parameter containing some additional data if it was successful.


How many ways are there to seat six people at a circular table where two seatings are considered equivalent if one can be obtained from the other by rotating the table?  I've been struggling with this for a while now and would like to ask for some help.

How many different arrangements are there of eight people seated at a round table, where two arrangements are considered the same if one can be obtained from the other by a rotation?


Having an issue trying to upload a file via php unit through selenium. This is the code for my current attempt.    public function testFileUpload()    {      $filePath = '/Users/cdolan/Desktop/CamsodaTest/mern.png';      $this->flingLogIn();      $this->webDriver->findElement(WebDriverBy::cssSelector('.btn.btn-upgrade-nav.no-follow'))->click();       $this->webDriver->findElement(WebDriverBy::cssSelector('.add-pic'))->click();      sleep(3);      $file_input = $this->webDriver->findElement(WebDriverBy::cssSelector('#upload-button'))->click();      $file_input->setFileDetector(new LocalFileDetector());      $file_input->sendKeys($filePath)->submit();   The test seems to run and complete with no errors, however it will not upload a file! It seems to get stuck on this screen and then closes out without uploading anything.    Any advice would be appreciated.

This is a canonical question, intended to provide a comprehensive answer to many related questions  During the course of a Webdriver test, I want to upload files. However, this opens a native file picker, which Webdriver doesn't seem to support interacting with. How do I interact with it?