TeX, LaTeX and Friends

bp2017

1:05 AM

Why the first line of every paragraph is always indented with \everypar{\noindent}?

6:06 AM

@bp2017 \noindent is for starting a new paragraph with no indentation. When the \everypar tokens are inserted, a new paragraph has already been started, and the indent inserted. Better to set \parindent to zero.

@bp2017 If this is latex, better not use \everypar anyhow, as it is used by latex. (Notably in lists.)

Harald Hanche-Olsen

7:56 AM

@bp2017 But if you must do this, {\setbox0\lastbox} after the paragraph has been started but before anything has been added to it, will remove the paragraph indentation (which is an \hbox). It can be used in \everypar.

Faheem Mitha

8:57 AM

I just noticed that \newcommand doesn't give an error if the number of arguments specified are not provided.

E.g. \newcommand\foo[2]{#1 #2}

Then \foo{foo} works. \foo{foo}{bar} also works.

Joseph Wright

@FaheemMitha Er, not exactly

Faheem Mitha

@JosephWright Well, it doesn't give an error, at any rate.

Joseph Wright

@FaheemMitha TeX will accept a balanced text here, which is zero or more tokens in braces or a single token without them

@FaheemMitha #2 in the first case is whatever the next non-space token is

Faheem Mitha

@JosephWright Oh, it just grabs the next thing available? Wonderful.

Joseph Wright

@FaheemMitha Yes: try making the replacement text #2 #1 and you'll see it more clearly

Faheem Mitha

8:59 AM

Are those xparse functions any less, um, flexible?

Joseph Wright

@FaheemMitha No, because this is a fundamental feature of TeX

Faheem Mitha

@JosephWright Ok.

@JosephWright Suppose there is no next thing? There is not in my example.

No, I take that back. One sec.

Joseph Wright

@FaheemMitha There is some next thing unless you are at the end of the file

Faheem Mitha

@JosephWright See, for example:

\begin{document}
\foo{foo}{bar}\\
\foo{foo}
\end{document}

Where \foo is defined as above.

Joseph Wright

@FaheemMitha You do have stuff after \foo{foo}: \end is the next token

@FaheemMitha try a document that is just

\newcommand{\foo}[2]{#1 #2}
\foo{oh no!}

and you get

Runaway argument?
! File ended while scanning use of \foo.
<inserted text>
                \par
<*> test.tex

?

Faheem Mitha

9:03 AM

@JosephWright I see.

@JosephWright Is TeX actually trying to typeset \end here, then?

Joseph Wright

@FaheemMitha Not typeset, you are just re-inserting the token into the input stream, and it does whatever it does (in LaTeX, \end is a macro, so gets expanded)

Faheem Mitha

@JosephWright That's what I meant.

Apparently expanded into nothing printable.

It would be nice if some error checking could happen here...

Joseph Wright

@FaheemMitha \end just looks up \enddocument here, and that then does all of the tidying up for a document

@FaheemMitha What do you mean?

Faheem Mitha

@JosephWright I mean, if \newcommand declares 2 arguments, then if the user clearly didn't intend to pass two args, an error would be thrown.

But it sounds like TeX can't tell the difference.

Joseph Wright

@FaheemMitha You can look ahead for a { token (if you don't want things to be expandable), but it's ... painful. Also, a lot of people would find it a surprise: for example, you used \newcommand\foo not \newcommand{\foo} above ...

Faheem Mitha

9:09 AM

@JosephWright That's true, I did. My mistake.

Joseph Wright

@FaheemMitha It's not a mistake, really: Lamport in his book does stick strictly to braces, but they are almost-certainly over-the-top for cases where only a single token is allowed (like \newcommand's first argument)

Faheem Mitha

@JosephWright I thought that was standard. All the examples have it.

Joseph Wright

@FaheemMitha Well yes, because it has to be a single token

Faheem Mitha

@JosephWright But it still works if you don't have the braces?

Joseph Wright

@FaheemMitha Yes, because TeX grabs a balanced text comprising one token in both cases

Faheem Mitha

9:18 AM

@JosephWright Sounds like brackets are "safer".

Joseph Wright

@FaheemMitha Yes, which is why Lamport's book always uses them

Faheem Mitha

Ok.

David Carlisle

@FaheemMitha actually not, they allow you to do \newcommand{\foo1}{something} which passes in \foo1 as first argument (which then doesn't work)

Faheem Mitha

@DavidCarlisle Because TeX doesn't like the integer?

David Carlisle

@FaheemMitha yes the argument has to be a single token, using braces rather hides that fact as it lets you pass in an arbitrary token list

Faheem Mitha

9:22 AM

@DavidCarlisle What's the advantage, though? Does it give a better error message?

Checking...

It gives the same error in both cases.

David Carlisle

@FaheemMitha mostly clearer documentation if you document the command takes a single token (expl3 N argument type) as opposed to a braced list (expl3 n)

Faheem Mitha

> ERROR: You can't use `macro parameter character #' in horizontal mode.

David Carlisle

@FaheemMitha then you didn't use the example I used. (but the behaviour in either case is spurious accidental expansion as newcommand does no error checking)

Faheem Mitha

@DavidCarlisle What was that example again?

@DavidCarlisle Are the xparse commands any betterm in any respect?

As in, in there any reason to prefer them from the pov of error checking?

David Carlisle

you get no error from either form here, but the behaviour is perhaps not what you expect

\documentclass{article}

\begin{document}

\newcommand{\fooa1}{something}

\newcommand\foob1{something}

\end{document}

Ulrike Fischer

9:32 AM

@DavidCarlisle did you see the complain about a mailing list answer here tex.stackexchange.com/q/498032/2388 ;-)?

Faheem Mitha

@DavidCarlisle Both definitions typeset "something". The first, with a 1 in front.

Joseph Wright

@FaheemMitha xparse does do more error checking up-front, yes

David Carlisle

@FaheemMitha the first one defines nothing and typesets 1something the second one defines \foob to be 1 then typesets something

Faheem Mitha

Wonderfully confusing if you weren't expecting it.

@DavidCarlisle It doesn't define anything?

David Carlisle

@UlrikeFischer yes @HenriMenke didn't like my follow question it seems:-)

Ulrike Fischer

9:34 AM

@DavidCarlisle better now;-)

wilx

So I have again been looking at fontspec documentation and I have noticed the Renderer property can take Harbuzz and Graphite values. But neither works here on Linux with TexLive 2019. Are those only available on some platforms?

David Carlisle

@FaheemMitha well it defines some internal tokens to nonsense values, it doesn't define\fooa or \fooa1 or anything else that you might access.

Faheem Mitha

@DavidCarlisle Oh. I know TeX doesn't like integers in macro names. But I can never quite remember why. Though I've read explanations.

Perhaps it makes it change modes or something.

David Carlisle

@FaheemMitha nothing much to do with integers here

Faheem Mitha

@DavidCarlisle Oh?

Ulrike Fischer

9:41 AM

@DavidCarlisle I found the question that triggered the lua question: tex.stackexchange.com/q/498021/2388.

@wilx no it is broken. I already made a bug report: github.com/wspr/fontspec/issues/370. Currently you have to use e.g RawFeature={mode=harf}.

wilx

@UlrikeFischer Yup, that's the same error I saw. Thanks.

Not that I have any use for that. I was just tinkering with my document. :)

Paulo Cereda

10:00 AM

Morning quack!

Joseph Wright

@PauloCereda QUACK

Paulo Cereda

@JosephWright ooh a duck

Joseph Wright

@PauloCereda Who are you who are so wise in the ways of science?

Paulo Cereda

@JosephWright Arthur ~~Reutenauer~~, king of the Britons? :)

Joseph Wright

@PauloCereda :)

Paulo Cereda

10:08 AM

@JosephWright now I want to watch the movie again. :)

Faheem Mitha

@JosephWright I'm guessing Monty Python.

Joseph Wright

@FaheemMitha Got it in one

Faheem Mitha

That was a guess, I didn't actually search.

Harald Hanche-Olsen

@FaheemMitha It has everything to do with category codes (catcodes for short) So yes, it does have something to do with integers, just not in the way you were thinking. Letters and digits have different catcodes.

Faheem Mitha

@HaraldHanche-Olsen Hmm. I hadn't registered that. But Ok.

Paulo Cereda

10:19 AM

@HaraldHanche-Olsen feline schemes. :)

Faheem Mitha

I thought all of ASCII was one code. And spaces were another. And then special characters had their own.

> 11. Letters: the alphabet.

Harald Hanche-Olsen

@PauloCereda I am currently living with my sister’s cats, so I know a bit about their schemes.

Paulo Cereda

@HaraldHanche-Olsen ooh

Faheem Mitha

I've not noticed numbers having their own catcodes.

Joseph Wright

@FaheemMitha No, they are catcode-12 ('other')

Faheem Mitha

10:23 AM

@JosephWright Oh, I see.

Harald Hanche-Olsen

@FaheemMitha It doesn’t seem that giving digits their own catcode would have been very useful.

Faheem Mitha

@HaraldHanche-Olsen Depends what one was going to do with them, I suppose.

I guess TeX probably wasn't going to add them together.

I don't see why they couldn't lumped in with the letters, though.

From a typography point of view, are they really different?

Joseph Wright

@FaheemMitha Well catcodes are more about TeX than typography

Faheem Mitha

@JosephWright I thought TeX was about typography.

Harald Hanche-Olsen

@FaheemMitha A control sequence is named by a backslash followed by one or more characters with catcode 11, or a single character with a different catcode. Giving digits catcode 11 would change the meaning of \count0. I guess it boils down to Knuth’s preference.

@FaheemMitha Yes but it’s also the mahinery to make typography happen.

Faheem Mitha

10:35 AM

@HaraldHanche-Olsen So, if you use integers to number stuff, then they have to be handled differently?

Joseph Wright

@FaheemMitha Well yes, you'd need to say \count 0 not \count0 or similar

Faheem Mitha

Like those toks things?

Joseph Wright

@FaheemMitha Also have numbers, yes

Harald Hanche-Olsen

@FaheemMitha Those too. And \box and \dimen and …

Faheem Mitha

I don't think I've even seen a register in the wild. They mostly seem to stay hidden.

Harald Hanche-Olsen

10:38 AM

@FaheemMitha Latex hides them. In the plain tex world, thet are all over the place. And in any latex class file.

Faheem Mitha

@HaraldHanche-Olsen I guess LaTeX hides a lot of stuff. By design.

A bit of a shock to the system if you need to do some actual programming.

Harald Hanche-Olsen

@FaheemMitha Absolutely!

Skillmon

2:27 PM

Is this really still on topic? tex.stackexchange.com/questions/498057/…

Joseph Wright

@Skillmon No

Skillmon

@JosephWright thanks.

Is stuff put into the TEXMFLOCAL considerably faster loaded than TEXMFHOME, does anyone have some experience with this?

egreg

@Skillmon TEXMFLOCAL uses ls-R files, whereas TEXMFHOME must be searched explicitly. Thus file finding is faster for the former.

@Skillmon I guess that with an SSD there is not so big a difference, provided TEXMFHOME is not large and deep.

Skillmon

@egreg reasonable assumption

Faheem Mitha

2:44 PM

Does anyone have a reference to a primer for Lua callbacks? What they are used for, how they can be used etc.?

Simple examples strongly preferred.

Joseph Wright

@FaheemMitha chickenize code is pretty good (seriously!)

Skillmon

@JosephWright I love how chickenize is always brought up when one asks for Lua examples.

Joseph Wright

@Skillmon 'Cause it's good Lua code, even if the outputs are ... special

Faheem Mitha

@JosephWright David mentioned that one once before. But it's not exactly a primer.

Skillmon

@JosephWright I love the guttenbergenize option (I'm studying at the same university where he plagiarized his doctor's thesis).

@FaheemMitha texdoc luatex starting from page 165 the Lua callbacks are described.

Faheem Mitha

2:57 PM

@Skillmon I see it. But it's a bit overwhelming. Mostly a list. Are there any callbacks invoked when calling a macro?

Joseph Wright

@FaheemMitha No

Faheem Mitha

@JosephWright Ok.

Skillmon

3:10 PM

@FaheemMitha well, depends, if the macro contains a \directlua...

Faheem Mitha

@Skillmon Hmm.

Skillmon

@FaheemMitha but without parsing the input there is no way of telling whether the user called any macro that is not handled by Lua (but you can hook into the file reading)

@DavidCarlisle \newcommand\foo{\directlua{bar}} is a macro, isn't it?

David Carlisle

@Skillmon sorry misread

Skillmon

@DavidCarlisle no problem :)

Faheem Mitha

@Skillmon Hook into the file reading?

Skillmon

3:15 PM

@FaheemMitha if I'm not mistaken you can alter the tokens TeX sees with Lua callbacks, before TeX tokenizes them (I'm not very familiar with how LuaTeX works)

Faheem Mitha

@Skillmon Probably. Oh, you mean as TeX reads the file?

David Carlisle

@FaheemMitha all the callbacks are listed and categorised in the luatex manual. not sure what else you are looking for

Skillmon

@FaheemMitha yes.

Faheem Mitha

Ok.

Skillmon

@DavidCarlisle I guess he looks for something which is a bit more explanatory on how to use them, what they do, containing small examples.

David Carlisle

3:17 PM

@Skillmon chickenize:-)

Skillmon

@DavidCarlisle was already proposed:

31 mins ago, by Joseph Wright

@FaheemMitha chickenize code is pretty good (seriously!)

Faheem Mitha

It's possible I don't need callbacks for now.

Skillmon

@FaheemMitha If you told us what you're trying to achieve, it would be easier to help you :)

Faheem Mitha

@Skillmon Nothing in particular really. Though I did, at one point, write macros inside a Lua string, inside a Lua loop. That did feel a little clumsy.

I was planning to post it as an answer here.

David Carlisle

@Skillmon yes I know

Skillmon

3:24 PM

36 mins ago, by Skillmon

@JosephWright I love how chickenize is always brought up when one asks for Lua examples.

Paulo Cereda

4:01 PM

ooh chickens

Skillmon

5:09 PM

@PauloCereda not as tasty as ducks.

Paulo Cereda

@Skillmon oh no

cis

It is 39.4 deg Celsius today.....

..............................................

Haw-Haw!
I hacked pgfmath into a CAS; with GNUPLOT:

\newcommand\Function[3][fixed,precision=6]{%%%%%%%%%
\sbox{\mycalc}{%%
\begin{tikzpicture}[]
\begin{axis}[]
\addplot[blue,domain = {#3:#3+0.1}] plot gnuplot[id=mycalc]{#2};
%\addplot[blue,domain = {pi:2*pi}] plot gnuplot[id=mycalc]{5};
\end{axis}
\end{tikzpicture}
}%%%
%\usebox{\mycalc}
%
\pgfplotstableread[header=false]{\jobname.mycalc.table}\tempdata%
%\pgfplotstabletypeset[string type]{\tempdata}
%
\pgfplotstablegetelem{0}{1}\of\tempdata
\pgfmathsetmacro\y{\pgfplotsretval}
\pgfmathprintnumber[#1]{\y}%

0

A: pgfmath / gnuplot: How to use gnuplot for complicated calculations?

Something like that: Short: % arara: pdflatex: {shell: yes} \documentclass[margin=5mm, varwidth]{standalone} \usepackage{pgfplots, pgfplotstable} \pgfplotsset{compat=1.16} \newsavebox{\mycalc} % See to: http://gnuplot.sourceforge.net/docs_4.2/node53.html \begin{document} \newcommand\Funct...

Skillmon

5:26 PM

I found a facebook page about LaTeX-memes.

Alan Munn

4

I especially like this one.

wilx

Heh. So meta.

Skillmon

scontent-dus1-1.xx.fbcdn.net/v/t31.0-8/…

Paulo Cereda

5:44 PM

@AlanMunn LOL

Zaz & Nolwenn Leroy - La Foule (2013)

►

@AlanMunn ^^ Two of my favourite French singers singing Edith Piaf. :)

Alan Munn

@PauloCereda <3

Paulo Cereda

@AlanMunn <3

Alan Munn

@PauloCereda My Spotify is mainly French these days.

Paulo Cereda

@AlanMunn That's good. :)

I need to move on to Spotify...

Joseph Wright

@PauloCereda Huh?

Paulo Cereda

5:50 PM

@JosephWright I don't use it. :)

Joseph Wright

@PauloCereda Ah

@PauloCereda I got a free account very early on ...

Paulo Cereda

@JosephWright really?

Joseph Wright

@PauloCereda Yes, I don't remember exactly when

In other news, anyone want to buy a Mac Mini ...

Paulo Cereda

@JosephWright Interesting.

@JosephWright I cannot afford one yet, but I want to get it in the future. :)

Joseph Wright

@PauloCereda It's an old one ..

Paulo Cereda

5:52 PM

@JosephWright oh I got it now

@JosephWright getting room for a new one, perhaps? :)

Alan Munn

@JosephWright Like all streaming platforms, it's pretty crap for classical music. Not so much because of what's there, but because of the lack of useful (and visible) metadata.