Function returning two things seperated by a comma in C
What does the comma operator do?
I know they have their adherents, but do more or less esoteric branches of mathematics such as Category Theory and/or Quantum Logic provide powerful tools for new theory development or are they just occasionally-useful presentational frameworks?  More particularly, is it worth investing the time to study these formalisms? Solidify thickness doesn't correspond to specified scale I'm Having trouble with setting the thickness applied by solidify. The selected block is 15 by 28 cm (single mesh sides) and the thickness of solidify is set to 3mm (pointing inwards). Checking off even thickness makes it even worse. I was using the function in a different object earlier today and it worked just fine. Is there something I'm missing or is this just a bug?   Feel free to treat me like an idiot, I've literally started using blender yesterday :) Calculating the longest distance within polygon in QGIS I want to calculate the "diameter" of polygons in QGIS.  The "diameter" defined as the distance between the two most distant points of the polygon.  I couldn't find a fitting solution in the field calculator. Maybe you have some ideas? Integration by partial fractions; how and why does it work? Could someone take me through the steps of decomposing  $$\frac{2x^2+11x}{x^2+11x+30}$$ into partial fractions?   More generally, how does one use partial fractions to compute integrals $$\int\frac{P(x)}{Q(x)}\,dx$$ of rational functions ($P(x)$ and $Q(x)$ are polynomials) ?    This question is asked in an effort to cut down on duplicates. See .  Also see . Can you catch a native exception in C# code? In C# code can you catch a native exception thrown from deep in some unmanaged library? If so do you need to do anything differently to catch it or does a standard try...catch get it? Sex worker student offering her (lawful) services One of my students is an escort/stripper and she has offered me (and other faculty in my department) her "services". I am pretty sure my initial reaction of "thanks for letting me know, now can you answer the question about how to calculate the standard deviation", may not have been the best reaction. The offers have continued. My head of school is aware of the issue, and has asked if I want him to do anything.  Is the student doing anything wrong by offering her services to me? For what it is worth, prostitution is legal in the UK. Is this any different then a student telling me she works in a restaurant?  What is the correct response in a situation like this? Conditional \endinput I want to prevent processing rest part of a package in case if it is loaded not from lualatex. For some reason I cannot load ifluatex package, so I borrowed definition of \ifluatex from that package and invented the following chunk of code:  \expandafter\ifx\csname luatexversion\endcsname\relax % = not \inluatex   %\typeout{^^J********************** not LuaTeX^^J}   \PackageError{babel}{     ^^J\space\space * Option russianu is intended for LuaTeX only.              ^^J\space\space * Option russian  is used instead.                     }   \relax   \input{russianb.ldf}     \let\@next@action\endinput \else   %\typein{^^J********************** LuaTeX^^J}   \let\@next@action\relax \fi \@next@action   It seemed to work but Is there a better solution. In particular, it is desirable to avoid introduction of \@next@action because it is used the only time.  Just to explain: my goal is to hack babel with option russian to make it working painlessly with LuaLaTeX without any additional hacks (as described, eg, in  and ) Let $p&gt;3$ be a prime. Prove that $24 \mid p^2-1$.   I know this is very basic and old hat to many, but I love this question and I am interested in seeing whether there are any proofs beyond the two I already know. When transiting Moscow (SVO), citizens of which countries need a transit visa? How does pointing a CNAME on my domain to a service-provider's server enable them to offer customized services? Does the  tag position in HTML affects performance of the webpage? Dual-boot boot menu does not show up after installing Ubuntu 15.10 alongside Windows 10 How to specify the SMTP server in PHPMailer? The following time-frequency correspondence illustration is in .    Also a gif animation version (if the animation doesn't show, please open the following image in a new window):    This picture has so much explanatory power, and I would like to replicate it in TikZ for future use.  Here is what I came up with:  \documentclass{minimal} \usepackage{tikz}  \begin{document} \begin{tikzpicture} [x={(1cm,0.5cm)},z={(0cm,0.5cm)},y={(1cm,-0.2cm)}] \draw[-&gt;,thick,blue!90] (0,6.5,0) -- (6.2,6.5,0) node[right] {Frequency}; \draw[-&gt;,thick,red!90] (0,0,0) -- (0,6.5,0) node[below] {Time}; \draw[-&gt;,thick] (0,0,0) -- (0,0,2) node[above] {Magnitude}; \foreach \x in {0.5,1.5,2.5,3.5,4.5,5.5}{   \draw[blue!50] (\x,0,0)   \foreach \y in {0,0.02,...,6.28}{     -- ({\x},{\y},{sin(\x*\y*(157))/sqrt(2*\x)})   };   \draw[blue!90, thick] (\x,6.5,0) -- (\x,6.5,1/\x); }  \end{tikzpicture} \end{document}   This is the output so far.    I have two questions:   How to produce that red superposed sine wave of all the blue sine waves? I don't know if there is a sum function or I have to use loop yet again? How to make the camera projection in TikZ more similar to the perspective in that wikipedia illustration?   Any suggestion and tweaking of the parameters I used in the sample drawing are welcome as well.  Thanks in advance!    Update 1:  Here is a new version using tikz, more readable than the first one. Yet the superposition of the sine waves are done manually...I still don't know how to use foreach to produce a sum.  \begin{tikzpicture}[x={(1cm,0.5cm)},z={(0cm,0.5cm)},y={(1cm,-0.2cm)}] \draw[-&gt;,thick,black!70] (0,6.5,0) -- (6.2,6.5,0) node[right] {Frequency}; \draw[-&gt;,thick,black!70] (0,0,0) -- (0,6.5,0) node[below right] {Time}; \draw[-&gt;,thick] (0,0,0) -- (0,0,2) node[above] {Magnitude}; \foreach \y in {0.5,1.5,...,5.5}{ \draw [cyan!50, domain=0:2*pi,samples=200,smooth]   plot (\y,\x, {sin(4*\y*\x r)/\y }); \draw[blue, ultra thick] (\y,6.5,0) -- (\y,6.5,1/\y); } \draw [red, thick, domain=0:2*pi,samples=200,smooth]  plot (0,\x, {sin(4*0.5*\x r)/0.5 + sin(4*1.5*\x r)/1.5 + sin(4*2.5*\x r)/2.5 + sin(4*3.5*\x r)/3.5 + sin(4*4.5*\x r)/4.5 + sin(4*5.5*\x r)/5.5} ); \end{tikzpicture}   The result is as follows: Solving "mv: Argument list too long"? I have a folder with more than a million files that needs sorting, but I can't really do anything because mv outputs this message all the time  -bash: /bin/mv: Argument list too long   I'm using this command to move extension-less files:  mv -- !(*.jpg|*.png|*.bmp) targetdir/ Short story identification: society partitioned off by high wall How do you parse and process HTML/XML in PHP? AMT stock option scenario Is it possible to run Microsoft Office 2010? Examples:        Data can be imported to and exported from the application.    Data can be imported and exported from the application.   Data can be imported to the application and exported from it.                  The manager defined the products that should be added to and removed from the store.   The manager defined the products that should be added and removed from the store.   The manager defined the products that should be added to the store and removed from it.      I assume that the third sentence is correct in my examples. My question is whether the two other sentences are correct.