How to stop this javascript count down when finished?
Stop setInterval call in JavaScript
Allow cancelling of stars from message Currently, the only way to cancel stars in a chat transcript is when the chat-message is visible in the chatroom's sidebar.    However, in a fast-moving, multi-star chatroom, the window of opportunity to cancel can be short, and rapid changes in starring can quickly make this impossible to do in a timely way.  We use stars as markers in moderator chat events (where the Community managers disseminate important information to the moderator teams) as well as for town halls during elections.  Feature request: Allow mods/room owners to cancel stars from the chat message menu box, including in the transcript. Chicken Stock gelatinous What is the number of invertible $n\times n$ matrices in $\operatorname{GL}_n(F)$? $F$ is a finite field of order $q$. What is the size of $\operatorname{GL}_n(F)$ ?  I am reading Dummit and Foote "Abstract Algebra".  The following formula is given:  $(q^n - 1)(q^n - q)\cdots(q^n - q^{n-1})$.  The case for $n = 1$ is trivial.  I understand that for $n = 2$  the first row of the matrix can be any ordered pair of field elements except for $0,0$. and the second row can be any ordered pair of field elements that is not a multiple of the first row.  So for $n = 2$  there are $(q^n - 1)(q^n - q)$ invertible matrices.  For $n\geq 3$, I cannot seem to understand why  the formula works.  I have looked at Sloane's OEIS A002884.  I have also constructed and stared at a list of all $168$ $3\times 3$ invertible matrices over $GF(2)$.  I would most appreciate a concrete and detailed explanation of how say $(2^3 - 1)(2^3 - 2)(2^3 - 2^2)$ counts these $168$ matrices. REST API composite query: How do I use the result of a query subrequest in the referenceId of another subrequest? Mathoverflow - why so different How can I stop being prompted to unlock the 'default' keyring on boot? Prove that $L(V,W)$ forms a vector space Let $V$ and $W$ be vector spaces over a field $F$. Let $L(V,W) = \{T:V\to W : T \text{ is linear} \}$, that is, $L(V,W)$ is the collection of all linear functions from $V$ to $W$. For $S,T \in L(V,W)$ and $a \in F$, define new functions $(S+T):V \to W$ and $ aT :V \to W$ by $(S+T)(x) = S(x)+T(x)$ ; $(aT)(x) = a(T(x))$.   Prove that $S+T$ belongs to $L(V,W)$ and $aT$ belongs to $L(V,W)$. Let $G$ be a connected planar graph with a planar embedding where every face boundary is a cycle of even length. Prove that $G$ is bipartite.  Any hints/tips will be greatly appreciated. Why is ++i considered an l-value, but i++ is not? Why is ++i is l-value and i++ not? No sound in Ubuntu except at log in I installed Ubuntu 12.04 a month ago and am using it till now. I failed to notice that all this time there was no sound at all while running Ubuntu, even while playing a game in Wine. The weird thing is that only the startup sound comes when I log in (Indian/African drum tone), then comes the utter silence.  I tested both Digital Output (S/PDIF) and the speakers in the sound settings but can hear nothing.  Any help? Is it possible to cancel or clear a notification created by using notify-send? So I wrote a little script that makes sure a certain user plugs in a laptop when he logs on (it disables if he doesn't). The script uses notify-send to tell him to plug it in. If he plugs it in, the script quits. Is it possible to clear the notification automatically when he plugs it in? I'm thinking it might require somehow getting the process id spawned by notify-send and killing that PID, but I don't know how to do this.  Here's the current script:  #!/bin/bash   cat /sys/class/power_supply/BAT0/status OUTPUT="$(cat /sys/class/power_supply/BAT0/status)" echo "${OUTPUT}" if [ "${OUTPUT}" = "Charging" ] || [ "${OUTPUT}" = "Unknown" ]; then     echo charging or full elif [ "${OUTPUT}" = "Discharging" ]; then     notify-send -i /home/evamvid/Documents/Programming/OokiNoUse/power25.png "Hey there brother" "plug it in"     COUNTER=0 while [ "$COUNTER" -le 12 ] do     cat /sys/class/power_supply/BAT0/status     OUTPUT="$(cat /sys/class/power_supply/BAT0/status)"     echo "${OUTPUT}"     if [ "${OUTPUT}" = "Charging" ] || [ "${OUTPUT}" = "Unknown" ]; then         exit     elif [ "${OUTPUT}" = "Discharging" ]; then         COUNTER=$(($COUNTER+1))         echo $COUNTER         sleep 1     fi done fi Writing someone else's master's thesis: Unethical and illegal? It is really difficult for me to decide on this situation: when someone calls me and asks for work-for-hire for his/her thesis. I don't know what to do. I want to help and earn money but I think this way of earning money is unethical.  I think that receiving the title of thesis and giving back prepared manuscript is the intention that some people have, when asking for their thesis to be written.  There are plenty of websites offering such services!   The question is that: Is it legal and or ethical to write someone else's master's thesis as work-for-hire? Are functions of independent variables also independent? How do I extract text that lies between parentheses (round brackets)? How we differentiate between flash memory and SD card memory? Mapping JSF .xhtml files to no extension How to find the sum $$\sum^n_{k=1} (k^2+k+1)k!$$  What I tried as follows :   $$\sum^n_{k=1} (k^2+k+1)k!$$  =$$\sum^n_{k=1} (k^2)k!+ \sum^n_{k=1} (k)k! + \sum^n_{k=1} (1)k!$$  Now we can write $\sum^n_{k=1} (k^2) $ as $$\frac{n(n+1)(2n+1)}{6}$$ but what to do with $k!$ please guide thanks....... Add days to JavaScript Date How to add days to current Date using JavaScript. Does JavaScript have a built in function like .Net's AddDay? I can't understand where the final keyword is really handy when it is used on method parameters.    If we exclude the usage of anonymous classes, readability and intent declaration then it seems almost worthless to me.   Enforcing that some data remains constant is not as strong as it seems.    If the parameter is a primitive then it will have no effect since the parameter is passed to the method as a value and changing it will have no effect outside the scope.  If we are passing a parameter by reference, then the reference itself is a local variable and if the reference is changed from within the method, that would not have any effect from outside of the method scope.    Consider the simple test example below. This test passes although the method changed the value of the reference given to it, it has no effect.  public void testNullify() {     Collection&lt;Integer&gt; c  = new ArrayList&lt;Integer&gt;();           nullify(c);     assertNotNull(c);            final Collection&lt;Integer&gt; c1 = c;     assertTrue(c1.equals(c));     change(c);     assertTrue(c1.equals(c)); }  private void change(Collection&lt;Integer&gt; c) {     c = new ArrayList&lt;Integer&gt;(); }  public void nullify(Collection&lt;?&gt; t) {     t = null; } Metric is continuous, on the right track? Let $X$ be a metric space with metric $d$. Show that $d:X\times X\rightarrow \mathbb{R}$ is continuous.   The problem is taken from Munkres Topology second edition, Section 20.  I know that if $d$ is a metric on $X$ then $d:X\times X\rightarrow \mathbb{R}$. My thinking is that the topology that is on $X$ is the topology induced by the metric $d$, and that the topology on $X\times X$ is the product topology on that space where we take the basis to be $$\mathcal{B}=\{ U \times V \mid \text{ $U,V$ both open in $X$}\}.$$ Am I on the right track to say that we define some new metric on $X\times X$ and show that this metric induces the same topology as the product topology and then work with the function $d$ as a function between metric spaces to show continuity? The question doesn't mention anything about defining some new metric and I've tried to solve the problem by looking at $X\times X$ as having the product topology, but in picking some point $(x,y) \in X\times X$ and some neighborhood around $d(x,y)$ in $\mathbb{R}$, I haven't yet found the way to make a neighborhood around $(x,y)$ which maps into the neighborhood around $d(x,y)$.