.... and the winner is .... ^^^^^ @UlrikeFischer CONGRATS!

@Mico Pinging you again

@marmot in Vernier question from yesterday, in 3d with rotation, I think the rate at which the scale rotates is not equal to the handle of the Vernier moving in ;)

@UlrikeFischer give us a weather update ^^

@marmot happy day, mr. marmot!

@marmot ;-) I added an edit to my answer. <<< @Raaja

Very nice @UlrikeFischer

@PauloCereda this deserves to be an answer in the Groundhogday (have my +1) ;)

@DavidCarlisle I did beat @Skillmon! So I put in an order for a cider. And I mean real english dry cider, not cidre or some modern foreign reimplementation based one pears or pineapples.

@UlrikeFischer congratulations!

just noticed that jfbu deleted his profile. Does anybody know why?

@Skillmon ;-). I added this to the answer: As winner I will ensure that over the next seven weeks the weather is perfect for some people in some places at some times. I already got a number of wishes:

@UlrikeFischer I vote for -5°C and much snow!

@Skillmon should it be actually snowing or should only be lots of snow of the ground?

@UlrikeFischer snowing every second day, the other day sunshine (but still -5°C and no melting).

@Skillmon I suggest the west alps, high enough.

@UlrikeFischer but I'm in Bayreuth and can't go on a vacation right now :(

@Skillmon I'm trying to arrange for snow in Bayreuth for the second half of the month.

I'm still trying, from time to time, to understand luatex's treatment of \Uleft and \Uchar as applied to absolute values and norms. I discovered that it gets it wrong even with cm fonts. Here is evidence, in plain tex to keep the number of potential offenders down:

\input luaotfload.sty

\newdimen\size \size 21pt
\def\test{
  \ifdim\size<4.5pt \cdot
  \else
    \Uleft  height \size depth \size axis |
    {\advance\size -1pt \test}
    \Uright height \size depth \size axis |
  \fi}

$\test$

\bye

Seems they work best with integer multiples of 3pt.

Does anyone with a newer luatex want to try it? I am on 1.07.0 (TL 2018).

@HaraldHanche-Olsen I get the same with newer luatex. You could ask on the luatex list, if and how it is supposed to work with legacy math fonts (remove then luaotfload, it is not relevant). With context (and so an open type math font) it looks like this.

@marmot Happy Groundhog Day! Will you reveal what the special surprise is or shall I?

@samcarter ooh surprises

@PauloCereda not only surprise, but special surprise :)

@samcarter ooh

@UlrikeFischer Thanks for looking. The luaotfload was there because I was using the Libertinus math font to begin with. I get similar results both with Libertinus and with STIX Two. What open type math font was used in your example? (I would try it myself, except I never so much as had a look at context.)

@HaraldHanche-Olsen the default font in context is latin modern math (and I have to know enough about context to build test files as you get much faster answers with them ...)

@samcarter oh a conspiracy.

Hello everyone. I've never seen this construction before, \def\mylst{{{"1b", "2b", "1a", "2a"}} as well as the call `\mylst[mod(\x-\y+8,4)] of these answer: tex.stackexchange.com/a/472297/138900 What is this structure? Do you have any documentation on this subject?

@UlrikeFischer have any multi-line descriptions you want to upload?

@AndréC the def is just a def and if you expand it out it's just some pgf synatx for accessing items in a list. The "call" isn't a call it is just data passed to \pgfmathsetmacro

@DavidCarlisle I'm planning a luaotfload update in the next week and can then try.

@DavidCarlisle Thank you very much, this intrigues me even more because I didn't find any documentation on this subject in the TikZ manual. Do you know where in the pgf manual this is documented?

@AndréC does pgf have a manual? @UlrikeFischer never told me about that.

@AndréC it's just this, which shows that \zzz is c:

\documentclass{article}

\usepackage{pgf}

\begin{document}

\pgfmathsetmacro\zzz{{"a","b","c","d"}[2]}
\show\zzz

\end{document}

@DavidCarlisle hm projection

@DavidCarlisle huuuum

@PauloCereda huuuum[0,5]=hm ?

@DavidCarlisle car/cdr? :)

@PauloCereda \show\@car

@DavidCarlisle ooh

@DavidCarlisle Yes the pgf and tikZ manual is called pgfmanual.pdf :-) Your ECM does not produce anything on my system.

@DavidCarlisle I was pinged by @car, lol

@CarLaTeX better than getting hit by one. :)

@PauloCereda for sure!

@AndréC yes it will, on any system, it produces no output just shows the definition of \zzz in the log. delete \show if you would rather typeset \zzz than see its definition

@samcarter I will certainly provide a surprise but this does not prevent you from providing one/ ;-)

@DavidCarlisle ^^^ Arrays are described in detail on p. 999 of the pgfmanual.

@DavidCarlisle why should you need it? You have a gold pgf badge.

@UlrikeFischer I don't need mythical sources

@marmot very suspicious, seems like that's 666 but you are holding it the wrong way up.

@DavidCarlisle Both of them match zzz, so why do you care?

@Skillmon That's a real shame. He was an excellent contributor.

@Skillmon Fighting with a user, writing complaints in longish shouting all-caps, 2 comments got flagged and deleted because of this, becoming angry about this, not talking even though there were sensitive approaches, self-initiating deletion.

Probably a deeper reason, when self-deleting after years due to what happened on a day

No secret as it happened visibly in public comments with explanation, but after deletion this off-topic discussion and rants have been cleaned up.

@StefanKottwitz Could you contact him and ask him to come back?

@Skillmon He accused me and a moderator of bullying him.

@Raaja Hmhh, could well be, but could you perhaps be more specific? (All I was doing was to impose a linear relation between the two, and then there is a mod condition for a full turn for the "wheel".)

@StefanKottwitz didn't see the conversation. It's a shame.

@marmot if ever you need tikz help from a real tikz expert

@CarLaTeX He decided to not respond any more and to not talk about this, so, no. But he can come back at any time with a new account.

@StefanKottwitz It's a pity to lose a skilled user, but that's it...

@UlrikeFischer I'm happy to inform you, that as part of your win of the Groundhog Challenge, you get to choose the next animal (or other being) for the tikzlings (or a custom duck if you prefer) :) (cc @marmot)

ooh a platypus

@PauloCereda I second this! @UlrikeFischer

@Skillmon <3

@PauloCereda Oh, this looks funny!

@samcarter Or a being. ;-)

@DavidCarlisle A true master piece, indeed.

@marmot I explicitly allowed also non-animal beings :)

@marmot ooh a bee-ing

@samcarter Oh yes. I read too fast...

@PauloCereda ^^^ bee-ing

@samcarter ooh Das Bee

@PauloCereda All letters correct, just a few missing in between: B<i>e<n>e

@samcarter ooh Molto Bene

A lot of bees

@egreg @CarLaTeX ^^

@PauloCereda perfect!

There are so many odd symbols to be found in unicode. I wonder who why ⦞ (U+299E ANGLE WITH S INSIDE) esists? And why no angles with any other letters inside? It appears that the unicode-math package assigns this symbol to \angles, which I was going to use for \langle…\rangle constructs. Well, I am doing that anyhow, but now I have to explicitly override that other definition in \AtBeginDocument. Oh well.

@HaraldHanche-Olsen it was added at 3.2 as part of the sitipub/stix submission, so we could blame @barbarabeeton

@DavidCarlisle -- i guess you can blame me for the name, but the reason that there aren't any angles with other letters inside is that this symbol appeared in the monotype symbol collection (metal type) with the meaning "multiple angles".

@barbarabeeton it looked like a "include legacy set" inclusion:-)

@barbarabeeton Ah well, in that case both the unicode name and the tex name make sense. A separate symbol for multiple angles makes less sense to me, but I guess someone somewhere had a desperate need for such a symbol.

@HaraldHanche-Olsen -- since it was monotype, i suspect that was used in (elementary) geometry textbooks.

@DavidCarlisle Is there a handy place to look up such information? It's not the first time I felt curious about the background for some unicode symbol.

@HaraldHanche-Olsen I used this: unicode.tex = everything I know about unicode

@HaraldHanche-Olsen w3c.github.io/xml-entities/unicode.xml (the xml view not the rendering you see in a browser)

@HaraldHanche-Olsen entry is:

      <character id="U0299E" dec="10654" mode="math" type="other">
         <unicodedata category="Sm" combclass="0" bidi="ON" mirror="Y" mathclass="N"/>
         <mathlatex set="unicode-math">\angles</mathlatex>
         <AIP>angles</AIP>
         <entity id="angles" set="STIX"/>
         <operator-dictionary form="infix" lspace="3" rspace="3" priority="270"/>
         <description unicode="3.2">ANGLE WITH S INSIDE</description>
      </character>

Why doesn't the pdftex manual state that \pdfstrcmp does expand its arguments fully?

And why do I learn just now (from looking into \pdfstrcmp) that pdfTeX also implements \pdfmatch.

@DavidCarlisle Okay. For some odd reason, my browser wouldn't download the file. I had to copy the link and use curl to get a copy.

@HaraldHanche-Olsen I inherited that file from Sebastian Rahtz, but I've had it since about 1997 or so, shuffling the information around as things changed. It's the master source for the entity names in mathml and html these days.

@Skillmon But \pdfmatch is mentioned in the pdftex manual right after \pdfstrcmp?

@Skillmon I think "string" is the hint.

@HaraldHanche-Olsen exactly how I found it just now. Never looked into the pdfstrcmp entry in the manual up to now (as I was wondering whether it mentions the full expansion).

@DavidCarlisle yeah, because in TeX we totally think 'every macro expanded' when we read string? :)

@Skillmon yes, as in "not a token list"

@DavidCarlisle then why does \tl_to_str:n do a \detokenize in l3, instead of an e-type expansion? Is this a bug?

@Skillmon in expl3 str means the kind of thing returned by \string that is catcode 12 or 10 token list

@DavidCarlisle exactly, and that is what I understand as string in TeX, the thing that \string does, not a full expansion. Perhaps I'm too stupid...

@Skillmon the pdftex manual is like the texbook, you need to read the source or test the implementation first and then interpret the words given that information.

@DavidCarlisle that might be the correct approach to it.

@HaraldHanche-Olsen -- i have a really nastily formatted table (ascii only) where i recorded most of the information where various items came from. i suppose i can make it available. but it isn't "finished" -- i was taken off the project before i had a chance to resolve some problems caused by the reuse of some temporary pua id's during the creation of the font. but i think most of the unicode assignments are reliable. it hasn't been touched since 2007. would that be useful?

@barbarabeeton It might be fun to have a look, for sure. But more for curiosity's sake than any real use.

@HaraldHanche-Olsen -- well, i have less than a week before i lose access to it. so if it might be useful to someone, i have to do something now. (@DavidCarlisle -- should i make it available from the tug box?)

@CarLaTeX Fortunately, there are still his 11 packages on CTAN ctan.org/author/burnol

@AndréC Let's hope he'll come back

@AndréC Yes, quite a few are really useful. etoc is one that should get more attention, in fact, it's really nice, but people don't know it much. Or maybe they just like flags.

@barbarabeeton Well, if I get a copy, I'll hang on to it at least, might reformat it into something more useful and make it available to others, but I can't know what could be done without having seen it.

@UlrikeFischer People in California are already complaining about the weather....

@marmot The weather here is crazy. Two days ago, -22, today it's 6.

@AlanMunn To me these look very similar. Both are even integers, none of which is a prime. ;-)

@marmot But they're both palindromes. (If you ignore the - sign.)

@AlanMunn True, but I thought your point was a dramatic change of weather.

@marmot Trust me, the difference between -22 and 6 is substantial. It's the difference between winter coat vs sweater and rain shell.

@AlanMunn Oh, wait. 6 is a perfect number, 22 is not. Are you sure it was not 28?

@marmot Kind of the same for you but when it's 19 and 22.

@AlanMunn 19 is not a perfect number AFAIK.

@marmot It never got that cold here, I don't think this week. In other places I've lived though, yes.

@marmot No but you Southern Californians complain about how cold it is for anything below 20 it seems.

@HaraldHanche-Olsen -- okay. i've posted them so that you can look at them. go to tug.org/~bnb/stix-tables.html and you will find links to two files. both are plain ascii. the "main table" is very large. the file with the layout description is much smaller, and can be viewed directly in the browser (well, it did that for me) so you can see what you're up against.

@barbarabeeton yes you could thanks (@HaraldHanche-Olsen my xml version is far easier to use:-) I spent many a happy hour cross checking that data against barbara's table:-)

@AlanMunn Here it is really much more rainy this winter than in the previous few years. (And yes, people in Southern California complain that it is too cold when temperature drops below 23 degrees Celsius, and too hot if it is above 25 degrees. Luckily, most of the time there is no reason to complain.)

@marmot Also we should get very worried if the temperature reaches the next perfect number after 28. (It can't even do that in the - direction).

@DavidCarlisle -- but i don't think your xml version identifies the sources of the items. i thought that was what @HaraldHanche-Olsen was interested in. (for the assignments, though, i agree about ease of use. i just didn't,. and don't, have the tools necessary to manipulate xml files in the way i needed to munge that table -- but could use utility sorts to great advantage.)

@barbarabeeton a few differences from the last version i had, i suppose I had better check against unicode.xml again:-)

@AlanMunn 496 degrees Kelvin are good for sauna....

@DavidCarlisle -- no. don't count on it. the one i posted is from 2007. i guess i should mention that in the file with the links.

@AlanMunn I don't know his packages. After one of his comments, I asked him to answer a question using his xint package, he didn't want to, but finally he did. tex.stackexchange.com/questions/454345/… He was discreet, certainly too discreet to make his packages better known.

@barbarabeeton I just compared against stix-tbl-public.txt which might be a filtered version? unicode.xml has some historical data such as AFII entries but not kept up to date (and I don't have as many entries as you do for \angles it seems)

@DavidCarlisle -- what's the date of your file? i just looked at what can be seen in the browser file, and it has much less info than my table.

@barbarabeeton Okay, thanks, downloaded. I will have a look later. Got other things on my agenda for the rest of the evening.

@barbarabeeton the stylesheet rendering in the browser discards most of the information, if you save the file and look at the xml you will see typical entries like :

      <character id="U029A0" dec="10656" mode="math" type="other">
         <unicodedata category="Sm" combclass="0" bidi="ON" mirror="Y" mathclass="N"/>
         <latex>\Elzlpargt </latex>
         <mathlatex set="unicode-math">\gtlpar</mathlatex>
         <Elsevier grid="bi9" ent="z.lpargt">
            <desc>left parenthesis, gt</desc>
         </Elsevier>
         <APS>lpargt</APS>
         <AIP>arcr</AIP>
         <entity id="gtrpar" set="STIX"/>
         <entity id="lpargt" set="8879-isoamsc">

@CarLaTeX He is a former student of the Ecole Polytechnique (the most difficult with ENS in France). It's the elite, so changing his mind will be complicated.

@barbarabeeton so it has the entity and character names as far as I know them and also the uniocde character class data and the data from the tables from the unicode math TR

@AndréC Ooooh

@DavidCarlisle -- okay. yes, what you show does have more info. i'll take a closer look sometime after i'm finished cleaning up and out of here. but, as i said, until i get all my tug and personal files transferred to someplace else, i can't afford the time. if i lose my tug archives, never mind some personal records, that would be disaster.

@barbarabeeton sure look after your records first, and good luck with this week.

@marmot Its just a minor (most probably) off-topic remark. I meant, when you rotate and push the handle at a angular velocity (v_1), the scale of a Vernier will also rotate at the same angular velocity (v_1). However, in your answer, the angular velocities are different ;)

@Raaja Yes, that's what I meant by linear relation. (Well possible that I screwed it, but at least I tried to implement this proportionality.)

@Raaja better now? (The relation was indeed linear, I think, i.e. as it should be, but the offset was not really intelligently chosen.)

@Skillmon if someone could explain what a platypus is

@PauloCereda you might be in need of that bat

@DavidCarlisle oh what happened?

England won at Rugby (don't mention the cricket:-)

@DavidCarlisle Oh my!

@samcarter oh no, Gert is protesting, he says it looks like a Dortmund player.

we are 2 down in a 3 match series against the west indies, do you think we have a chance?

@DavidCarlisle I... I have no idea!

@UlrikeFischer A masked drunk duckmarmot at midnight perhaps, see a platypus typing in the chat:

@PauloCereda I'll get @egreg to explain the maths to you, but so far we have lost 2, they have won two and there is one match left....

@DavidCarlisle ooh there's a chance

@PauloCereda I hope you are better at cricket than mathematics

@marmot sorry currently handling the antarktis. California must wait a few days.

@UlrikeFischer It looks like you got the two confused. The weather is really awful today.

@PauloCereda speaking of Rugby, we could ask @egreg or @CarLaTeX if they watched the Scottish match

@DavidCarlisle in Italy this is called soccer.

@marmot ?

@DavidCarlisle What you guys call rugby is called soccer in Italy.

@DavidCarlisle bring on the ducks!

@marmot really? That's just weird since soccer is an abbreviation of association football, mostly used in the US to distinguish it from American football:-)

@DavidCarlisle Well, this was an attempt to politely inform you that rugby does not really play a role.

@marmot it plays a role of filling in when the cricket team is being demolished in another part of the world.

@DavidCarlisle ooh

@DavidCarlisle Cricket? What is cricket?

@marmot ask @PauloCereda, he carries the bat with him at all times.

@DavidCarlisle I thought that's his cell phone.

@marmot self-protection?

@marmot yello

@StefanKottwitz Probably. In the US they also have such bats for something called baseball.

@marmot isn't this weekend the soup bowl thing, do they all get soup?

@DavidCarlisle normally that is a perfect day for cycling because there are no cars on the street. too bad it's raining!