Where to ask questions related to the junction between programming and mathematics?
Which computer science / programming Stack Exchange sites do I post on?
Vortex in liquid collects particles in center At xmas, I had a cup of tea with some debris at the bottom from the leaves.  With less than an inch of tea left, I'd shake the cup to get a little vortex going, then stop shaking and watch it spin.  At first, the particles were dispersed fairly evenly throughout the liquid, but as time went on (and the vortex slowed, although I don't know if it's relevant) the particles would collect in the middle, until, by the time the liquid appeared to almost no longer be turning, all the little bits were collected in this nice neat pile in the center.  What's the physical explanation of the accumulation of particles in the middle?  My guess is that it's something to do with a larger radius costing the particles more work through friction... How can i integrate one SFDC org to another SFDC using Rest Api I am trying to integrate one Salesforce org to other org by using Oauth setup, I wanted to use  use consumer key and consumer secret key in my REST class to connect with the org, after connection part completion, I want to access Get(), Put(), Post(), etc. Including the ability to set Oauth and Authorization headers needed for Salesforce Rest API calls.  Actually I'm new in REST implementation so can you please explain me by using code samples. how to add xsl attribute A curious integral The following integral has been on my mind for a while $$\int_0^\infty \frac{\sin(x)}{e^x-1}\,\mathrm d x \tag{$\dagger$}$$    Let us indicate the integrand as $f(x)=\frac{\sin(x)}{e^x-1}$. The following are a couple of observations.   The integrand can be extended by continuity in $0$ since $$\lim_{x\to 0}f(x)=\lim_{x\to 0}\frac{\frac{\sin(x)}{x}}{\frac{e^x-1}{x}}=1$$ This is the original reason I started playing around with this integral. Mathematica yields the result $$\int_0^\infty \frac{\sin(x)}{e^x-1}\,\mathrm d x=\frac{\pi}{2}\textrm{Coth}(\pi)-\frac 12 \approx 1.076674047$$ which, following numerical evidence, seems correct. Complex analysis may be useful here, since the integrand is a holomorphic function on $\mathbb C$. I tried writing $\sin(z)=\frac{e^{iz}-e^{-iz}}{2i}$, but I was not able to find an appropriate integration contour to solve the problem. The $-1$ in the denominator breaks the simmetry of the expression. This made most of my substitutions useless.   Can this integral be evaluated correctly, preferrably through complex analytic methods? Do conjugate priors just lead to a posterior that is a modification of the parameters of the prior? We know, for example, that the conjugate relationship between the classic beta-binomial is as follows:  \begin{align}  y &amp;∼ \mathcal{Bin}(n,\ θ)  \\  θ &amp;∼ \mathcal{Beta}(α,\ β)  \\ θ|y &amp;∼ \mathcal{Beta}(y + α,\  n − y + β) \end{align}  Notice how the posterior is just a change in parameterization compared to the prior. Is the posterior of conjugate priors just a change in parameters? What is the difference between apt and apt-get? I read about the new fancy progress bar which was added to apt 1.0 in  and how to enable it . However on running sudo apt-get update, I did not see the fancy progress bars. On reading the second link again, the solution explicitly requires you to use sudo apt update.  Hence my question is the difference between apt and apt-get. I thought they were one and the same. I recently received an old iMac secondhand.  I have no way to reach the original owner. I am trying to upgrade the OS software, but the prompts demand the administrator's name (which is auto-filled) and password (which I do not have).  I understand why these security features are in place, but is there any way in the world for me to access Admin. privileges without the password? If G is a group of order n=35, then it is cyclic I've been asked to prove this.   In class we proved this when $n=15$, but our approached seemed unnecessarily complicated to me. We invoked Sylow's theorems, normalizers, etc. I've looked online and found other examples of this approach.    I wonder if it is actually unnecessary, or if there is something wrong with the following proof:   If $|G|=35=5\cdot7$ , then by Cauchy's theorem, there exist $x,y \in G$ such that $o(x)=5$, $o(y)=7$. The order of the product $xy$ is then $\text{lcm}(5,7)=35$. Since we've found an element of $G$ of order 35, we conclude that $G$ is cyclic.   Thanks. I've read a new study which suggests that yawning may help you keep a cool head. Also, the findings might hold some hope for sufferers of insomnia, migraines, and even epilepsy.  Is there any conclusion about what the function of yawning is and why do we yawn? Why are cryptography algorithms not exported to certain countries? There have been strict laws about the export of crypto software to certain countries. I can understand the intent, but never gauged the fact that there is nothing stopping these countries from developing their own crypto software. So why limit the export?   And in light of the recent NSA revelations, of backdoors being engineered into crypto algos, wouldn't the export of such compromised algorithms have helped to unravel secrets? How do I tell if matrices are similar? I have the following code:  Using cmd As SqlCommand = Connection.CreateCommand     cmd.CommandText = "UPDATE someTable SET Value = @Value"     cmd.CommandText &amp;= " WHERE Id = @Id"     cmd.Parameters.AddWithValue("@Id", 1234)     cmd.Parameters.AddWithValue("@Value", "myValue")     cmd.ExecuteNonQuery End Using   I wonder if there is any way to get the final SQL statment as a String, which should look like this:  UPDATE someTable SET Value = "myValue" WHERE Id = 1234   If anyone wonders why I would do this:   for logging (failed) statements for having the possibility to copy &amp; paste it to the Enterprise Manager for testing purposes Can I disable GNOME legacy tray in 17.04? How do I install "non-free firmware" (wifi driver) from USB? (Debian) Possible Duplicate:          As a English non-native speaker it is difficult for me to understand when I must use present perfect or past simple because in my official language there isn't the present perfect tense. I know that present perfect is related to something that happened in the past but its result is important now. But for instance:        The message has been sent.   The message was sent.      Please help me point me out any examples/contexts where I should use 1. instead of 2. Nick Fury told Captain America that he has been "asleep" for nearly 70 years. If Dominic Cooper was playing Howard Stark Senior (grandfather of Tony Stark) then it is fine, but if he was playing Howard Stark (father of Tony Stark) then after 70 years he should be around 90 or above.  Tony Stark, his son, should be 60 to 70 years.  Is that possible?  Tony doesn't look 70 years in The Avengers. Can't find boot-repair package for the newest version of Ubuntu How to log out user from web site using BASIC authentication? Error with square bracket in table \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] &amp; [] &amp; [] &amp; [] &amp; []\\         [] &amp; [] &amp; [] &amp; [] &amp; []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   I cannot run the above code, latex returned an error about missing number, but I can't see anything I am missing.  And the weirdest thing is that  \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] &amp; [] &amp; [] &amp; [] &amp; []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   This code works.  Anyone have any idea? How do I restore .bat files association with the system (make them run when double-clicked)?