Whenever I put 2 trees onto a document, the system always tells me I am missing \tikzlibrary{calc} on the second tree (I have the same line for both trees) on this line \draw[dashed,rounded corners=10]($(1-1) + (-.2,.25)$)rectangle($(2-2) +(.2,-.25)$); even though I have it right above it.
I've been googling for some time now, and can't find the manual for the TikZ library calc. All I see is people using it. Where can I find the manual or some info?  Is it the same as the LaTeX package calc? The latter doesn't seem to mention TikZ in the manual.
Apps retaining data after being deleted After most recent kernel update (4.15.0-44-generic) my tablet freezes whenever plugged into docking station I performed the most recent kernel update on my Dell 5290 2-in-1 earlier today.  But moments after I plug it into its docking station, the screen flickers, blanks and freezes.  The only item left on the screen is the mouse pointer, and it is stuck.   If I leave the tablet not plugged in, it runs just fine.  It seems to be the docking station that triggers the freeze.  That said, I can log into the tablet via ssh even with the screen frozen.  So the system is still running.  But if I try to reboot the tablet via the reboot command, nothing appears to happen. sudo reboot -f will reboot the system, while sudo reboot will not.  Any ideas where I should start looking to identify this problem? Finding specific users by their location and a tag score 3D arrows with TikZ Asymptote does give 3D arrows when drawing three dimensional figures (they even have shade!). Could we fake it with TikZ? Here's an example, manually written, with just one arrow worked:  \documentclass{scrartcl} \usepackage{tikz} \usetikzlibrary{arrows.meta} \begin{document} \begin{tikzpicture}[-&gt;,scale=2]   \draw[&gt;={Triangle[width=3pt,length=5pt]}] (0,0,0) -- (1,0,0);   \draw[&gt;={Triangle[width=3pt,length=5pt]}] (0,0,0) -- (0,1,0);   \draw[&gt;={Circle[sep=-.9pt,width=3.08pt,length=2pt]Triangle[width=3pt,length=5pt]}] (0,0,0) -- (0,0,1); \end{tikzpicture} \end{document}     But that's (wrongly) manually calculated by trial and error (apart from the fact that it's not perfect, seeing how the other two axis —x and y— are oriented, it should have certain slant). It would be nice to have an interface like the other arrows  &gt;={3D[length=⟨real length⟩,width=⟨real width of the base⟩]}   Which would then calculate from those values (and, of course, also taking into account x=⟨x vect⟩,y=⟨y vect⟩,z=⟨z vect⟩)  Circle[sep=⟨value⟩,width=⟨value⟩,length=⟨value⟩,slant=⟨value⟩] Triangle[width=⟨value⟩,length=⟨value⟩] % And I'm not sure if `slant=⟨value⟩`                                        % is necessary in this Triangle case   Example  Using the code from the answer (thanks to Symbol1), for instance, this code (taking the idea from another question, link in the comments)  \begin{tikzpicture}[x={(0cm,1cm)},                     y={({cos(30)*1cm},{sin(30)*-1cm})},                     z={({cos(20)*1cm},{sin(20)*1cm})},                     thick,                     scale=3]   \pgfmathsetmacro{\ax}{.4}   \pgfmathsetmacro{\ay}{.6}   \pgfmathsetmacro{\az}{-.6}   \pgfmathsetmacro{\bx}{.4}   \pgfmathsetmacro{\by}{-.7}   \pgfmathsetmacro{\bz}{-.8}   \draw[densely dotted,thin] (\ax,\ay,\az) -- (\ax,0,\az);   \draw[densely dotted,thin] (\ax,\ay,\az) -- (0,\ay,\az);   \draw[densely dotted,thin] (\ax,0,0) -- (\ax,0,\az) -- (0,0,\az);   \draw[densely dotted,thin] (0,0,\az) -- (0,\ay,\az) -- (0,\ay,0);   \draw[densely dotted,thin] (\bx,\by,\bz) -- (\bx,0,\bz);   \draw[densely dotted,thin] (\bx,\by,\bz) -- (0,\by,\bz);   \draw[densely dotted,thin] (\bx,0,0) -- (\bx,0,\bz) -- (0,0,\bz);   \draw[densely dotted,thin] (0,0,\bz) -- (0,\by,\bz) -- (0,\by,0);   \draw[-{Cone3}] (0,0,0) -- (1,0,0) node[right] {$x$};   \draw[-{Cone3}] (0,0,0) -- (0,1,0) node[above right] {$y$};   \draw[-{Cone3}] (0,0,0) -- (0,0,1) node[below right] {$z$};   \draw[-{Cone3}] (0,0,0) -- (0,0,-1) node[above left] {$-z$};   \draw[thin] (0,0,0) -- (0,-.9,0);   \draw[-{Cone3}] (0,0,0) -- (\ax,\ay,\az) node[below left] {source};   \draw[-{Cone3}] (0,0,0) -- (\bx,\by,\bz) node[above right] {sim}; \end{tikzpicture}   gives this figure What is meant by "object serialization"? Can you please explain it with some examples? How to import a module given its name as string? How do I tail a log file and keep tailing it when the latest one changes date? The new notice for protected questions looks like this:     Earn 10 reputation in order to answer this question. The reputation requirement helps protect this question from spam and non-answer activity.  The phrasing of this notice leaves out a lot of info, and is incorrect in many cases:  In the case where the user has just created their account on the site (whether or not they have the association bonus of +100), the default 1 for signing up does count toward the required 10. The message implies that the user has to earn 10 more reputation for a total of 11 (or 111), while the actual requirement is 10 (or 110).  If the user just registered and started off with the association bonus, then later lost part of it (e.g. through bounties or making a downvoted post), earning 10 reputation is not enough to answer protected questions. According to the literal wording of the notice, earning 10 reputation is enough regardless of previous rep loss, but this is not the case.   The easiest fix that can be made, to at least fix part of the problem, would be to explicitly indicate that the association bonus does not count. This was implemented in the prior protected question notice in response to , but was omitted from the new notice. This omission  , and adding this back would remove that. Can we please fix this notice? SPSite and SPWeb object dispose inside foreach loop More homework help.  Given the function $f:A \to B$.  Let $C$ be a subset of $A$ and let $D$ be a subset of $B$.  Prove that:  $C$ is a subset of $f^{-1}[f(C)]$  So I have to show that every element of $C$ is in the set $f^{-1}[f(C)]$  I know that $f(C)$ is the image of $C$ in $B$ and that $f^{-1}[f(C)]$ is the pre-image of $f(C)$ into $A$.  Where I'm stuck is how to use all of this information to show/prove that $C$ is indeed a subset.    Do I start with an arbitrary element (hey, let's call it $x$) of $C$? and then show that $f^{-1}[f(x)]$ is $x$?  I could use a little direction here...  Thanks. Is it a problem if a UK visa was issued but not used? Last year, my wife and I were issused 6-month visieor visas for the UK. She did not travel with me and, therefore, didn't use her visa. I am currently applying for a visitor visa for my daughter and myself.  Will the fact that my didn't use her visa have any negative affect on our new application? How do the comment replies (aka &quot;pinging users&quot;) work?  Who can I send an @reply to? How do I respond to a specific user when entering my comment? Will they be notified? What do people mean when they talk about &quot;pinging&quot; another user?  Related: How can I report bugs with or request features for the Stack Exchange mobile apps? I'm using the official Stack Exchange mobile app for iOS or Android, and  My app crashed! It doesn't look good on my new smartphone. It won't run after I updated my device. I noticed another bug. I have an idea for a new feature which is currently not in the app.  How do I report bugs with or request features for the iOS and Android apps? Also:  I've used the built-in functionality of the app to report a bug or submit a feature request. Did I do the right thing? The app prompted me to post on Meta after an error occurred. Should I post about it here? I'm wondering why the latest version is from 2017. I've heard rumors that the apps are no longer supported; is that true? I can't find the app on my device's app store anymore! Where did it go?     We get a lot of bug reports from users about the mobile apps, which are unsupported, and at the moment, there is no centralized Q&amp;A pair for those to be closed as duplicates of (the relevant answers are spread across multiple unrelated questions). This question is an FAQ proposal, to serve as a directly-related duplicate target for those questions. Prove that if $P$ is a $p$-Sylow subgroup of $G$ and $N \triangleleft\&gt; G$ then:    $ PN/N $ is a $p$-Sylow subgroup of $G/N$ $P \cap N $ is a $p$-Sylow subgroup of $N$ I have a SQL Server 2005 database using the full recovery model. If I execute the following commands:  ALTER DATABASE test SET RECOVERY SIMPLE; ALTER DATABASE test SET RECOVERY FULL;   or   BACKUP LOG test WITH  truncate_only;   Then try to run a log backup:  BACKUP LOG test TO  DISK = 'backupfile.bak'   I receive the error message:     BACKUP LOG cannot be performed because there is no current database backup.   Question:     How do I check that I will not be able to take a log backup, without running a backup log command? When my phone MOTOROLA G3(2015) is updated to Marshmallow, its not showing files when connected to PC. While connecting, it shows options as charing only, PTP, MTP, MIDI. When I select MTP, it shows the external card, but not showing the contents, where as internal memory is detected and all files are shown. $\sum\limits_{n=1}^{\infty}\frac{1}{1+z^n}$, $|z|&gt;1$.  There are two facts that my professor uses that I am confused about.  The first is: $|1+z^n| \geq ||z|^n-1|$, I believe this is true for any $|z|$.  The other is: $\frac{1}{|z|^n-1} \leq \frac{2}{|z|^n}$, I believe this is also true for any $|z|$.  Can anyone prove these statements for me? How to reduce the number of authors above >3 to 'First Author et al., (year)'? I am looking for an app that can monitor my C: (system) drive and find which program is creating a folder, with the rather generic name TEMP1\, on that drive.  I wouldn't mind if it could hook the creation of files too – as there a couple of files created as well (quite probably from another process). Google does not help me, as the names of those files are a bit generic too (not as TEMP1 though – dvmaccounts.ini and dvmexp.idx).   The problem is that every time I delete those, they are recreated on startup, so the utility I'm searching must start up on boot and also start fast. It should also be really clever, as my C: drive is huge. I thought the new Apple font was called San Francisco, but I cannot find it in the font list of the Keynote.app for my Mac. Is it called another way or it is not available for Keynote?  I am currently using OS X El Capitan.