Hi. How do you label equations, sections, etc? By numbering or by name?

\documentclass{article}
\usepackage{hyperref}
\usepackage{amsmath}
\begin{document}
Pythagoras' Theorem:
\begin{equation}\label{pythagoras}
    a^2+b^2=c^2
\end{equation}
where $c$ is the length of the hypotenuse and $a,b$ is the length of the other two sides.

Besides, Albert Einstein is most well-known for his famous formula
\begin{equation}\label{einstein}
    E=mc^2.
\end{equation}

Now we have to prove \eqref{pythagoras} and understand \eqref{einstein} properly.
\end{document}

and

\documentclass{article}
\usepackage{hyperref}
\usepackage{amsmath}
\begin{document}
Pythagoras' Theorem:
\begin{equation}\label{eq:1}
    a^2+b^2=c^2
\end{equation}
where $c$ is the length of the hypotenuse and $a,b$ is the length of the other two sides.

Besides, Albert Einstein is most well-known for his famous formula
\begin{equation}\label{eq:2}
    E=mc^2.
\end{equation}

Now we have to prove \eqref{eq:1} and understand \eqref{eq:2} properly.
\end{document}

what do you prefer?

@JouleV Names or words are better to remember!

@Kurt I'd choose the first one. Of course, in a short document, names are far better than numbers, but IMO in very long documents it is very easy to have two similar labels for two different equations.

I don't know if anyone has the same issue, but I can't avoid the repetition of labels.

@JouleV Then use longer labels, two, three ore more words. Then you can make each label existing only one time ...

@JouleV You can find very interesting labels on very highly cited papers on the arXiv. Examples include "interpolistheworstbandonearth" in a paper that introduces a LaTeX switch that allows you to transition from the east coast metric to the west coast metric... 😉

@marmot Not 'nickelbacktheworstbandonearth' ? I'm surprised.

@AlanMunn I wouldn't exclude this. (The author is actually not too far, by US standards, from where you live.)

@marmot That could be anywhere between Chicago and Toronto. ;)

@AlanMunn Yes, that's very accurate: Northern Illinois University.

@CarLaTeX Someone was just asking for a TikZ version of the <s>Mona</s> Marmot Lisa. So sad that @samcarter is not around. :-(

@marmot It's really sad, but do not write mona alone in Italian, because it has a double meaning in some dialects :)

@CarLaTeX I tried to cross out M..a but it didn't work.

Another one ;-)

@ChristianHupfer congrats!

^^^ reflection invariant. again. ;-)

@marmot Guess when you will reach 100k :)

@JouleV Perhaps before the end of the month?

@JouleV in less than 5 days

I thought I could see when you reach 98989 but I'm too late :|

@JouleV These scores are not meaningful I think (and one can always go back, just award some bounties, I don't know if there is an upper limit on bounties one could award.

A palindrome for me, too ^^^

Oh my ... Today is flooded with palindromes...

Congratulations!

Incredible: answered now to an August 23rd's question and the OP immediately accepted!

@marmot Rotation invariant?

@mickep Yes by 180 degrees. ;-)

@CarLaTeX OP is exhausted. No water, no food, since August!

@mickep He has been anxiously waiting for months, lol!

@CarLaTeX I'm wondering why the OP didn't start a bounty if he needs an answer so much like that.

@JouleV Perhaps he didn't need the answer so much, but by chance he was online when I answered

@CarLaTeX Such chances are so rare.

@JouleV That's why it's incredible! :)

@JouleV using a number defeats the whole purpose of the \label system. Don't do that.

@DavidCarlisle Thanks for the suggestion!

@JouleV more specifically, the label mechanism is there as the numbers are automatically generated in the output and change as you edit in the source and so you need a mechanism to be able to refer to sections/equations without knowing their number. It is very confusing to look at a source ref of \ref{eq:5} that references equation 10

@marmot Last chance to take the survey: stackoverflow.blog/2019/02/07/…

Please, everyone take the Stack Overflow 2019 survey and complain about the bad design.

@CarLaTeX Thank you

@DavidCarlisle I think it is clear now why @Krishna had document changes between luatex 1.07 and 1.09: on the luatex list Patrick posted an example showing that font expansion has changed.

@UlrikeFischer yes just saw. Is that an engine change or a change in the matching lua code or...?

@DavidCarlisle well it could be a rounding problem somewhere due to lua52->lua53. But my guess is that it is an engine problem. Let's wait what Luigi says.

@DavidCarlisle I get a difference also without luaotfload and with \font\tenrm=phvr8t at 10bp, so it is the engine.

@UlrikeFischer I'm also interested to hear what he says about that other email:-)

@DavidCarlisle me too ;-).

@JouleV I think Leonardo built a time machine and copied this from you. ;-)

@DavidCarlisle Yes, but if you type QM notes, it is quite likely that at a given point you end up writing \label{eq:SchrodingerEq1}, \label{eq:SchrodingerEq2} and so on or \label{eq:SchrodingerEqInHAtom1}, \label{eq:SchrodingerEqInHAtom2} etc. if you manipulate these equations slowly.

@marmot using numbers in themselves is not bad, as long as you make it clear (to your later self) that the numbers are just making unique ids, not relating to the printed number it is using \label{eq:3} for the equation that happens to be number 3 in the current draft that is bad

@DavidCarlisle I fully agree with that.

@marmot It's the very first time I work with such a big document :) Only in standalone class but it takes 2.43 MB and GitHub can't display it fully ;-)

@JouleV Just imagine how hard it was for Leonardo. At that time computers had even less memory. ;-)

Look at it! I don't think we can produce that file ourselves with that accuracy in less than ten years. Maybe a book is needed to store the file.

And modern computers can do it in less than 10 seconds...

@JouleV That's probably true. (TikZ stands for "TikZ ist kein Zeichenprogramm.", meaning "TikZ is not a drawing tool." ;-)

@marmot otherwise translated as "tikz is not picture mode"

@DavidCarlisle Hmm, does that mean you will post a Marmot Lisa soon? ;-)

@DavidCarlisle You should prefer Tikz actually, because there is a z in it... but most likely it should be called Tikzzz for you to abjure that picture mode heresy ;-)

@ChristianHupfer only one z is not enough.

@UlrikeFischer That's why I proposed to rename Tikz to Tikzzz or Tikzzzzzzzzzzzzzz ....

@UlrikeFischer Did you get mail?

@marmot no.

@UlrikeFischer According to DHL you should get mail today.

@marmot oh. Real mail. Normally it should already have been here. I could check below. Wait a minute.

@UlrikeFischer looks like font expansion should be fixed

@marmot no nothing to see. But not really surprising, in the last time I often get DHL messages with "your package comes on friday" and then they bring it saturday.

@DavidCarlisle good - the new output looked rather bad in some places.

Good afternoon to all with all my heart.

@marmot How are you, you and driver? :-)

@Sebastiano I am sleepy and the diver is drowsy. How are you?

@Kurt Hi friend and good work.

@marmot perhaps time zone confusion. You are quite far away ;-).

@UlrikeFischer Yes, quite possible. But even in California it is Monday by now.

@marmot To be honest, I'm always very tired. This afternoon I slept for 3 hours and I woke up almost half an hour ago. In a while I'm leaving to do my mum's shopping: I'll have to buy the washing machine's laundry and the color saver. :-). I'm very tired because I work in two schools and my commitments have doubled. A strong hug. You're great!!!!!

@Sebastiano Hi Sebastiano. Did you succeed in correcting undefined labels?

@Sebastiano Mille grazie but I am not great....

@UlrikeFischer Hi :-) time zone confusion is into my mind: please help me to to get rid of the confusion and problems :-(

@UlrikeFischer Yes, and they will probably be surprised to learn that some of their cars by accident drove here. ;-)

@Kurt Fixing the labels is not a problem but it is the time I miss. When I come here I relax and am happy to have found some wonderful friends. You are part of one of them.

@Kurt I like to tell the truth for better or for worse. I also teach my students that. I had to select separately the premise of the book (the most important and most significant part of the content) and work on it this afternoon. Day 14 I will be in Catania for the first review.

@Kurt You can see the hour and the day of this file "premessa".

Best regards everybody. I go!

@marmot You are great, for my humble opinion.

@Sebastiano Yes, time is running ... And relaxing is important. And thanks.

@Sebastiano Good luck for that day!

@Sebastiano In Germany we say: Ich drücke Dir die Daumen! (Sorry, do not know if there is something like that in english and I do not speak italian.

@Sebastiano I think we should not make such statements on the chat, nor on the main site, since they could be taken as implying a "ranking" or something of this sort....

@marmot You mean rep points aren't an indication of greatness? I'm shocked.

@AlanMunn don't you consider the ability to copy images from Wikipedia to be a sign of greatness?

@DavidCarlisle The only true sign of greatness is the ability to render any desired image in picture mode.

@UlrikeFischer hmmmmm (also @JosephWright)

@DavidCarlisle As expected

@DavidCarlisle like my l3draw mail?

@JosephWright yes

@JosephWright yes (but note @AlanMunn's comment above)

@AlanMunn No, are they supposed to be? If so, how would you interpret my score, which is a complex number? Of course, for privacy reasons I can only reveal its absolute value. ;-)

@marmot 99999+0 i ;-)

@marmot You just don't want us to know that your actual score is negative? :)

I have a command that will format a 'todo' :

\newcommand{\todo}[1]{{\color{blue} \textbf{TODO : }}{\color{red} \textbf{#1}}}

I'm wondering if there's an easy way to make that appear in the contents page, having a list of the todo's might be useful

@baxx Did you see (for example) the fixme package?

no I haven't seen that

Or todonotes. They could be what you look for.

@baxx ctan.org/pkg/todonotes

Thank you I will try that now

\newcommandx{\improvement}[2][1=]{\todo[linecolor=Plum,backgroundcolor=Plum!25,‌​bordercolor=Plum,#1]{#2}}

is there anything obviously wrong with this?

taken from here tex.stackexchange.com/a/178806/69118

@UlrikeFischer and @DavidCarlisle I feel guilty that I didn't get around to posting a MWE for that luatex 1.07 vs luatex 1.09 issue

ah i need xargs

@Circumscribe No, it has a non-trivial phase, which is different from 0 or pi, simply because I used all my pi's up for the borders of the MWEs in my answers. :-)

@Krishna well it looks like it'll be fixed in luatex 1.10 so no harm done

@Kurt Incrocio le dita! In Italian language is the same thing :-) Thank you very much.

@marmot Ok, but I wrote it as a token of appreciation. I'm not mischievous and I don't even think about impropriety and that someone believes that my compliments can affect the score. My appreciation comes from the heart.

@Sebastiano This was not meant to be a criticism. I just feel we should not give attributes to users (OK, maybe calling mean users "mean" is an exception, but everyone knows it is a joke;-).

@mean you are not David Carlisle

@StefanKottwitz who will that have pinged? :-)

@DavidCarlisle not you!

@StefanKottwitz no because I am not mean

@DavidCarlisle And I checked before. No user is mean.

@StefanKottwitz shame:-)

@DavidCarlisle There is no @shame either.

@DavidCarlisle, @UlrikeFischer Interesting team mails from that chap from a well-known Linux entity

@JosephWright ?

@DavidCarlisle Ooh, not to the team, just Bruno, Frank and me ... I'll forward

@JosephWright oh for crying out loud:-)

@DavidCarlisle Seen it?

@JosephWright yes

@DavidCarlisle Guess you see why I've not named them here :)

@JosephWright "tradition" seems to involve running time backwards

@DavidCarlisle :)

@JosephWright meanwhile that other non-team email probably should be discussed on the team list.....

@DavidCarlisle The HB one?

@JosephWright yes

@DavidCarlisle oh

@DavidCarlisle Totally expected outcome

@JosephWright yes but it leaves open the question of what to do, I'm not sure if it's feasible to have a texlive setup such that a binary lua module is loadable in all texlive platforms (maybe Karl would know)

@DavidCarlisle Almost certainly not. We are back with the issue that the LuaTeX team have a very definite vision.

@JosephWright this makes it all seem very easy so long as the basic code has been compiled on all the platforms, but it always seem more complicated in practice lua.org/pil/8.2.html

@DavidCarlisle I meant a very small binary, very few things beyond Lua itself

@JosephWright yes but if we take that as given, the question is could texlive build a shared library on all the platforms that it builds luatex and could the difference in shared library naming conventions all be hidden in a suitable lua, so the end result was the same as an extended engine as far as higher level code concerned

@JosephWright I suppose i could try building it on cygwin....

@DavidCarlisle That's one for the TL list I think

@JosephWright if that is soluble then really there is no issue, already as far as i understand the windows texlive build moves things between being linked into the executable and being implemented via shared dll libraries, and noone really notices any difference.

@DavidCarlisle I guess .. outside my area of expertise

@DavidCarlisle In other news, are we going to just save all the primitives in the 2e kernel ...

@JosephWright why is \(pdf)primitive so useless? if you have the feature at all, don't you want to do \expandafter\let\expandafter\savedyear\primitive\year ?

@JosephWright and just hope it's Ok in plain? (if anyone is using expl3 from plain)

@DavidCarlisle If a plain user moves \year, they are own their own!

@DavidCarlisle Er, yes, it's not ideal: the closes you can get is \protected\def\year{\primitive\year} or similar (I guess a \count). That gets you the value ...

@DavidCarlisle It's probably Hans' fault

@JosephWright is there really no devious use of \primitive that can be used to re-generate a csname with the original definition

@DavidCarlisle Don't think so, no

@DavidCarlisle It's not expandable

@JosephWright so define \tex_foo:D in the format and defien \primitive to be \csname\string#1 stripped of the :D and tex-\endcsname

@JosephWright I know, which makes it fairly useless, as far as i can tell.

@DavidCarlisle Yup

@DavidCarlisle I was just thinking we define \@@foo for all \foo

@DavidCarlisle It's not my fault

@JosephWright hm

@PauloCereda I knew you would take credit for it. ;-)

@JosephWright that would be the 2e way but more likely to clash with packages doing something similar already and then blows a few hundred csnames that you will re-do as :D so I was thinking use this as a thin end of a wedge to slip in expl3 just startung with the names....

@DavidCarlisle Quite frankly, I think 'Unless you are FMi, and you change a primitive, expect LaTeX to break' would be a fair position

@DavidCarlisle There is that, aye

@DavidCarlisle I use like 200 for Unicode case changing

@JosephWright but people copy code from the core packages and kernel and we re-define \end and \everymath and \par (at times) and \input and \over and ....

@JosephWright I couldn't afford 2 to make a sensible error message for \pagestyle{zzz} (we really should fix that:-)

@DavidCarlisle I think I did say FMi can change primitives ;)

@DavidCarlisle Yeah, different mindset

@JosephWright my mindset never really changed:-)

@DavidCarlisle \protected

@JosephWright scary newfangled ideas

I used to think \protected was my favourite e-TeX primitive, by now we have \expanded, which is almost-e-TeX, I'm conflicted

@DavidCarlisle :)

@DavidCarlisle But we do save them somewhere

@DavidCarlisle In the end, we are clearly going one way: probably you are right and we should just add ltnames or similar

@JosephWright ?

Just saw a strange looking imaginary unit in an arXiv paper, so I thought “let's have a look at the source”.

\newcommand{\ii}{\dot{\iota}}

wat?

@HenriMenke There are all sorts of conventions around, some use simply upright i's, others use the double-stroke lower-case i's that Mathematica uses, and so on. Personally I like each of them better than just italic i's and having to guess what e^{i\omega_i} means in a formula.

@marmot except my answer is better:-)

@marmot surely you are not accusing me of secretly editing my answer and invalidating your claim of its incorrectness?

@marmot I wonder if @egreg will be able to avoid the temptation to try to steal a tick with an expl3 g answer. personally I think any answer using g deserves a downvote:-)