Export CAD .STEP files format with Mathematica?
Is it possible to create .stp 3D model from Graphics3D ？
Does 'rm .*' ever delete the parent directory? The expression .* is expanded by bash to include the current and parent directories:  $ ls -la total 2600 drwxrwxrwx   2 terdon terdon 2162688 Sep 10 16:22 . drwxr-xr-x 142 terdon terdon  491520 Sep 10 15:34 .. -rw-r--r--   1 terdon terdon       0 Sep 10 16:22 foo $ echo .* . ..   If I run rm -rf .* on my Debian using GNU bash, version 4.2.36(1)-release and rm from rm (GNU coreutils) 8.13, I get this message:  $ rm -rf .* rm: cannot remove directory: `.' rm: cannot remove directory: `..'   Is this a GNU thing or is it POSIX? Are there any *nix systems where the command above will silently delete . and ..?  Also, is this a safety feature of the shell or of the rm command itself? Why square the difference instead of taking the absolute value in standard deviation? Restore main APFS container to full disk Adapt Ubuntu to a high-DPI resolution screen How can I adapt Ubuntu to a high resolution display?  I have a display with 3200x1600px on only 11'' and everything looks really tiny. Do the SSH or FTP protocols tell the server to which domain I am trying to connect? When using the ssh or ftp commands from the Bash shell, does the server that I am connecting to learn of the domain name used? I understand that the domain name is locally translated into an IP address via DNS. In HTTP, after that happens, the server is told the original domain name as well in order to serve the correct page, or to present the correct TLS cert (SNI).  host serverfault.com GET /   Does a similar phenomenon happen when connecting to ssh or ftp?  I ask because I am  trying to ssh into a server (GoDaddy webhosting) which expects a domain name, but is not letting me in when I try to connect via user@IPaddress as the DNS is not yet moved to the GoDaddy IP address. Modifying agsm.bst package bibliography output I would like to change the URL output from:  URL: the html link  into:  [Online]URL: [Accessed on]  I am using:  \usepackage[comma]{natbib} \bibliographystyle{agsm} Persist variables between page loads I have got codes like the following (generated by Kile). How can I add a caption. I guess I should have used the table environment. Is there any solution now?  \newcommand{\mc}[3]{\multicolumn{#1}{#2}{#3}} \begin{center} \begin{tabular}{rccll}      &amp;   &amp; \mc{3}{c}{Colin}\\      &amp;   &amp; a &amp; \mc{1}{c}{b} &amp; \mc{1}{c}{c}\\\cline{3-5} Rose &amp; \mc{1}{c|}{A} &amp; \mc{1}{c|}{(1,2)} &amp; \mc{1}{c|}{(2,5)} &amp; \mc{1}{c|}{(4,4)}\\\cline{3-5}      &amp; \mc{1}{c|}{B} &amp; \mc{1}{c|}{(7,4)} &amp; \mc{1}{c|}{(3,5)} &amp; \mc{1}{c|}{(0,6)}\\\cline{3-5} \end{tabular} \end{center} What is the penalty for dual US citizens who lie on the ESTA form in order to enter under VWP using their second passport? Number of total possibilities for an equation I need to find the number of possibilities for which the following equation exists:  $$x_1 + x_2 + x_3 + \cdots + x_{10} \leq 70$$  Each variable is a non-negative integer.  I tried simplifying the question to the point of finding the number of possible solutions to each equation seperatly:  $$x_1 + x_2 + x_3 + \cdots + x_{10} = 70,$$ which is ${79}\choose{10}$.  $$x_1 + x_2 + x_3 \cdots + x_{10} = 69,$$ which is ${78}\choose{10}$.  $$x_1 + x_2 + x_3 + \cdots + x_{10} = 68,$$ which is ${77}\choose{10}$, and so forth.  Then I thought about adding all of these together. This seems a bit too much work considering that the textbook solution is: ${80}\choose{10}$, and I can't seem to figure out the idiomatic way of approaching these kind of questions.   Any help is greatly appreciated. Should "move-to-chat" be provided on demand (as a button perhaps)? When comments get too chatty the move-to-chat feature asks if you'd like to move it out. But this often happens after the fact and thus doesn't prevent it.   I propose that:   Move-to-chat be provided as a button along side so that a user who knows their question or conversation may become drawn out may elect to preempt and take the conversation "off-line" JTable won't show column headers How to exclude a column from SELECT query? Plot Option Precedence while combining Plots with Show[] I'm using the alpha version of the android app on the first generation nexus 7 tablet.  The font size is a little bit small for my liking and I'm not able to pinch zoom to increase the font size.  Is this a feature that is planned in the release? Density of states for arbitrary dispersion relation If I have a 3D dispersion relation   $E=E(k_x, k_y, k_z)$ I have an equation for the density of states, which is   $D(E)=\frac{1}{\nabla_k E}\int\frac{dS}{(2\pi)^3}$  1) I am confused about the integral. What am I integrating over, exactly? It must have units of the $k$ vector, so it's a k-space integral, but what is the surface that is relevant?  3) Where does that equation come from, how is it derived? Require minimum reputation on the target site for migration I was wondering if it's possible to run an Ubuntu virtual machine using VirtualBox in background, I mean, without any window open.  The idea is to connect via SSH to the Linux host, that would be running in background.  Has anyone ever done something like this? Is it possible? Prove : $$ \text{If } \; x-\lfloor x \rfloor + \frac{1}{x} - \left\lfloor \frac{1}{x} \right\rfloor = 1 \text{, then } x \text{ is irrational.}$$  I think the way to go here is to falsely assume that $x$ is rational, thus having $x=\frac mn$ with $m,n$ integers and go with that, we also know that $x$ with the celling belongs to the integers and that $\frac 1x$ with the celling gotta be a $0$. Still can't prove it. Thank in advance ! how to find $|GL_2(F_p)|$ I need to find $|GL_2(F_p)|$, I am very very uncomfortable in counting, so please help here I proceed,  $\begin{pmatrix}a&amp;b\\c&amp;d\end{pmatrix}$ be such an invertible matrix, so we need and sufficient that $ad\neq bc$, so if i chose all non zero $a,b,c$ arbitrarily and chose $d\neq a^{-1}bc$ and form matrices then the cardinality   will be $(q-1)^3\times (q-2)$, well now if one of $a,b,c,d$ be zero then other three can be anything nonzero so in this case cardinality will be $4(q-1)^3$, so finally if two entries are $0$ then they must be opposite to each other i.e diagonally, but other two must be nonzero, so cardinality in that case $2(q-1)^2$, so total number is just sum of three cases.