@samcarter Normally Germans put too many "the" but here you seem to have forgotten one: "fearless duck" -> "featherless duck".

@marmot = dinner

@AlanMunn Oh no!

@marmot oh no

@StefanKottwitz OMG

@CarLaTeX The ship regained some power and is currently heading west at about 3 knots. Almost 400 of the 1300 people on board have been evacuated by helicopter. At the height of the crisis, they were literally minutes from the biggest shipping disaster in recent years. It could so easily have ended with more than 1000 deaths.

@HaraldHanche-Olsen OMG!

@CarLaTeX Indeed. Hustadvika is one of the most notorious areas along the Norwegian coast. No islands to shelter behind, big waves rolling in from the Atlantic, and shallows offshore leading to extreme breaking waves. There have been many shipwrecks there, at great cost of human lives. The ship was drifting powerless at 7 knots, just about a hundred meters from the shallows when they managed to regain some level of control.

@HaraldHanche-Olsen If it is so dangerous, why do they do cruises there?

@CarLaTeX The cruises typically go all the way up the Norwegian coast. It's a very beautiful place, totally worth it! But some stretches, Hustadvika being one of them, are too dangerous to traverse when weather is as bad as it was. They should probably have delayed their passage. They had already skipped one destination (Bodø) due to bad weather; perhaps the captain felt a certain pressure to catch up to their schedule.

@HaraldHanche-Olsen It terrible to risk people's life for economic reasons!

Some relevant news at nrk.no – perhaps google translate can help you make sense of it. And watch the video in the center below the top item. It may be blocked outside Norway, but hopefully not.

@CarLaTeX Yes, but we do not know yet what was the motive for the decision to go ahead. For sure, once the crisis is over, there will be all sorts of hearings. Better not rush to conclusions. But it does not look good at present.

Currently I see only one helicopter flying nearby. Why is the evacuation so slow?

Even when the weather is bad, I think there should be more helicopters.

@JouleV There is room for only one helicopter at a time hovering above the ship. They have four helicopters taking part in total.

@HaraldHanche-Olsen Yes, but there should be more helicopters on the sky at the same time.

Also, even highly trained rescue helicopter personell need a bit of rest. They've been going all night. And helicopters need refueling.

I zoomed a large area, and there is still only one

The helicopters probably don't show up while on the ground. The next one should take off in time to start hoisting passengers the moment the previous one is done.

Some ship details here

@HaraldHanche-Olsen The video is shocking, I didn't see the news on TV in Italy

@CarLaTeX Well, you've had your own cruise ship disaster. Maybe an almost-disaster far away is not considered newsworthy in comparison. And yes, I am glad I am not aboard.

Past track of the ship

@HaraldHanche-Olsen Oh, yes, the Condordia was worse! And there was also a man who tried to burn a bus with 50 children on board two day ago near Milan!

@CarLaTeX There are so many serious news around the world that newspaper can't report all of them.

@JouleV you're right

It seems off topic but an Antonov is coming right to the scene

@JouleV Probably just a coincidence. Flying high over, I presume. What site do you get these from, btw? I once knew where to get these, but have lost track. Hmm, googling flight radar I see several.

@HaraldHanche-Olsen I am using flightradar24.com

Aviation news often refers to this site so I think it is good

@JouleV Yeah, looking at it now. The Antonov is at 34000 feet, definitely coincidence there.

Rescue helicopter at 325 feet, ground speed 1 knot. Clearly working on hoisting passengers.

@HaraldHanche-Olsen Yeah. I have been tracking it for 15 mins and it doesn't seem to change position.

I really don't know who operates that helicopters. Most of the rescue helicopters are ~50 years old Sea Kings operated by the military.

@HaraldHanche-Olsen If the sky is clear the Antonov can take an image of the evacuation. But I don't think it is.

It's cloudy. Oh, I see now that the helicopter is operated by CHC Helicopter Service. That is a commercial company servicing oil platforms in the North Sea, among other things.

Hello everyonee

Denmark is sending a rescue helicopter. Not to help with this evacuation, but to bolster the Norwegian rescue services while they're busy with the cruise ship.

Suppose that we have to write \[\vec T:\Bbb R^3\to\Bbb R^3 "such that" M(\vec T)_{E,B}=\begin{pmatrix}1&2&0\\1&1&0\\0&0&2\end{pmatrix}\]

@manooooh Hello. As you can see, we've been going off topic this morning.

@HaraldHanche-Olsen yes, my first observation was the follow-up of the flight of an airplane :O

@manooooh Yes? I'd write \colon instead of :. But are you asking what to use in place of "such that"?

where "such that" is text. How would you write the latter? I would write it as: [\vec T:\Bbb R^3\to\Bbb R^3\;\text{such that}\;M(\vec T)_{E,B}=\begin{pmatrix}1&2&0\\1&1&0\\0&0&2\end{pmatrix}]

@HaraldHanche-Olsen yup!

Maybe we could use \[\text{\(\vec T:\Bbb R^3\to\Bbb R^3\) such that \(M(\vec T)_{E,B}=\begin{pmatrix}1&2&0\\1&1&0\\0&0&2\end{pmatrix}\)}\]

@manooooh Something like that, but perhaps I'd use more space around the text. I'd have to typeset it to be sure.

Actually, I'd probably prefer to have $\vec T:\Bbb R^3\to\Bbb R^3$ such that in the preceding text, leaving only the condition in the display.

@HaraldHanche-Olsen like \quad? But "such that" is the same as \mid i.e. | with a little space around it, so in that sense I think we would be incosistent?

@manooooh I would read \mid as “such that” only in a set constructor.

@HaraldHanche-Olsen oh... You would be even happier to know that the teachers of my university always use f:A to B/... :)) (my eyes bleed!)

@manooooh I know that is the conventional wisdom, but I am not too sure about the rationale for it. On occasion, I'd just use normal spaces within the \text{…}.

@HaraldHanche-Olsen even if we are enclosing a long formula with matrices etc?

@manooooh Honestly, I don't know for sure. Maybe someone else will speak up. But you'd probably want the matrix to be in display mode, which speaks against it.

@HaraldHanche-Olsen ok, no problem, I like your way of not putting all the formula in display. Thanks!!

@JouleV It's returning to land now. And I don't see any others in the air, still. A bit odd that, but perhaps they have decided to curtail the rescue. The ship has three out of four engines operational now, and they're escorted by two tugboats.

When Bertrand Russell announced his first child, a friend said, “Congratulations, Bertie! Is it a girl or a boy?”

Russell said, “Yes, of course. What else could it be?”

@PauloCereda These days, that seems much more complicated.

@HaraldHanche-Olsen Enumerated set? :)

@PauloCereda A continuum, perhaps?

@HaraldHanche-Olsen ooh

It's official now: The rescue operation is suspended while the cruise ship is towed to land. I guess the crisis is over, only the questions remain. And I shall stop spamming the chat with this stuff.

@manooooh No way! :-) For several reasons. You should write \vec{T} and \mathbb{R}. The command \Bbb has been deprecated for more than 20 years. The colon or the \colon command is personal preference (I use the latter). Using \text{ such that } is simpler, but “where” seems better.

@egreg hello! 1) \vec T is an efficient way to write when the parameter is atomic, so I see no reason to write \vec{T} (I'm the only person who sees the source code). 2) \mathbb{R} is tedious to write, so in my preamble I defined \renewcommand{\Bbb}{\mathbb}, which makes \Bbb not deprecated. 3) I think you are right with the use of \colon. (cont'd)

(cont'd) 4) Ok, I will use ...\text{ text here }.... I have been told that I have to write "such that", so I write that. I did not want to make a personal interpretation to leave things unchanged

Thanks!

I take this opportunity to ask you if in the following image you would use parentheses or not to denote the inverse:

Code: \[\begin{cases}\vec T(1,0,0)=(1,1,0)\\\vec T(0,1,0)=(1,0,0)\\\vec T(0,0,1)=(0,0,2)\end{cases}\implies\begin{cases}(\vec T)^{-1}(1,1,0)=(1,0,0)\\(\vec T)^{-1}(1,0,0)=(0,1,0)\\(\vec T)^{-1}(0,0,2)=(0,0,1)\end{cases}\]

(We do not discuss the use of cases in this example but about the use of parentheses). If we write \vec{T}^{-1} then the arrow and -1 are very close to each other, so the output is ugly. But I think if we are parentheses the output is ugly, too. Any suggestion?

But I think if we use parentheses*

@manooooh You're being inconsistent. Don't be. ;-)

@manooooh For instance, the editor will not break \vec{T} across lines.

@egreg the use of \vec A is not the kind of incosistency that any author can have. They are writing styles, and since I have found one reason that it is better than others, it is sufficient for me to adopt it

@manooooh Good luck. But don't say I didn't warn you.

@egreg Personally, I always turn off automatic linebreaking in my LaTeX files. In running text, I insert a newline after the end of every sentence, frequently behind commas, and in general I try to avoid breaking meaningful phrases while keeping lines short. Among other reasons to avoid \vec T, the one that occurs to me is if the code is to be parsed by something other than latex. Further reasons?

@manooooh Don't use \vec: it's ugly and old-fashioned.

@egreg On that, at least, I agree. But sometimes (rarely) you have to hold your nose and do it anyway.

@HaraldHanche-Olsen @manooooh Besides, a linear map is not a (geometric) vector.

@egreg Good point. But I wonder what causes the awful placement of the arrows in @manooooh's example?

Arrows are bad enough, but that is beyond bad.

@HaraldHanche-Olsen A thin space helps. ^^^^^

@HaraldHanche-Olsen Maybe half a thin space for the vector

@egreg Yes, but shouldn't the arrow be centered over the top of the T?

@HaraldHanche-Olsen DEK decided differently

@HaraldHanche-Olsen accents do usually account for the italic slope but the shift in cm over arrow is excessive, if people used over-arrows more there would probably be more complainants:-)

@CarLaTeX I promised not to spam the chat further with this, but I just learned that the Norwegian coastal express decided not to go out in the storm. These guys rely on some 120 years of experience sailing the Norwegian coast. Admittedly, their ships are smaller, but still …

@HaraldHanche-Olsen too much dangerous argh!

@CarLaTeX They are just now being towed into sheltered waters. (Click on ships to identify.)

@marmot Would a featherless duck be very cold in the water?

@samcarter Not if the water is boiling.

@samcarter I guess in Brazil it is OK.

@marmot I think a (live) featherless duck would have difficulties floating. They probably rely on trapped air in their feathers. They probably would not quite sink, but they'd be much deeper in the water than normal ducks. Look at cormorants for an example.

@HaraldHanche-Olsen On TV here, too, now

@HaraldHanche-Olsen You are inspiring @DavidCarlisle for bad ideas about boiling water and ducks

@marmot With @PauloCereda definition of freezing to be below 20\degree C this might indeed work

@HaraldHanche-Olsen But ducks have long necks, a bit lower in the water should not be a problem.

@HaraldHanche-Olsen Good point. We marmots usually do not like to swim, that's why I didn't think about that.

@samcarter Yes, and you have the explanation why he thinks that below 20 degrees it's freezing.

@marmot A well though through theory :)

@samcarter As I said, you forgot a the... ;-)

@HaraldHanche-Olsen They possibly have read Edgar Allan Poe.

@egreg :)

@samcarter quack. :)

@HaraldHanche-Olsen Quack quack! I'm on the train to chocolate heaven :)

@samcarter ooh

@samcarter And where is that?

@samcarter my glycemia rose up only looking at it

@CarLaTeX :)

@samcarter Yummy! I need to be careful with sugary stuff myself, so I always go for the dark chocolates. The darker, the better. They taste better, too.

(Do not underestimate the power of the dark side.)

@HaraldHanche-Olsen Nor the power of the duck side.

@HaraldHanche-Olsen -- Better taste to a point. 100% is a bit too intense for my taste. 70 - 90% is good.

@barbarabeeton I have never tasted 100% chocolate, so I wouldn't know. The darkest I can usually get is around 86%, and I don't feel the need to go much beyond that.

@HaraldHanche-Olsen I totally agree with the dark side. I usually stay in the 79-95 percent range. Once I had 99% chocolate and it was actually good, however one could only eat very small bits of it.

@samcarter I can't resist making the case for the fairafric project: Chocolate is made in Ghana from locally produced cocoa, and much of the profit stays in Ghana where it could actually do some good. I've had the good luck to be able to support the project through kickstarter.

@egreg my premise is that any vector must have an arrow at the top

@manooooh *Very* old-fashioned. And useless.

@manooooh Let G be a group and K a field. Then G is a subset of the group ring K[G], which is also a vector space over K. Therefore every element of G is a vector. Now use the arrow over every element of any group. ;-)

@egreg sorry my teachers did not teach using that definition, hence I never will use an arrow at the top of an element of any group

@egreg what I think is visually annoying is e.g. \vec{AB}. The arrow is very short. Do you have a better proposal (besides not using arrows)?

@manooooh \overrightarrow{AB}; it's possible to have a smaller arrow: tex.stackexchange.com/a/248297/4427

Lol! But I do not want smaller arrows :)... Thanks!

I did not remember overrightarrow since it seems that it was not made to denote a vector (vec=vector... uh)

@manooooh It's more commonly used for things other than vectors. In geometry, for example, one can use \overrightarrow{PQ} for the ray starting at P and passing trhough Q. But in high school geometry, it is more commonly just the vector from P to Q, which one learns later in life to write as Q−P.

@HaraldHanche-Olsen yes exactly!! \vec{AB} means B-A, but... I learned that from a subject called "Algebra and Analytic Geometry" (note the word "Geometry"), so? Should I treat the vector AB as \vec{AB} or \overrightarrow{AB}?

How robust would something like \ifx\foo\undefined instead of \ifcsname be (say\undefined is guaranteed to be undefined)?

@Skillmon Have you seen tex.stackexchange.com/a/31658/80496 ? Basically \ifx\undefined should be as robust as \ifdefined, but if you do not need non eTeX compatibility I do not see the point. \ifdefined also looks much nicer IMHO. If you want to replace \ifcsname you additionally have to remember that you can not do something like \expandafter\ifx\csname ...\endcsname\undefined, because \csname makes undefined names \relax.

@manooooh The arrow in \vec{AB} is way too short! You need to use \overrightarrow or @egreg's shorter variant. But of course, you should make a new command such as \vector for this use, rather than redefining \vec. One reason why redefining existing commands is risky, is that some package may redefine them again in an \AtBeginDocument hook.

@HaraldHanche-Olsen we never talked about redefining a command, but you are right. Thanks!

@Skillmon one of the main motivations for the etex versions was to avoid filling the string pool but that's less of an issue these days. in latex you can use \@ifundefined of course, especially the latest releases which use \ifcsname internally

@manooooh I do get conversations mixed up all the time sometimes.

Hi, all! I'm trying to move my list subscriptions to Gnus, instead of my inbox. But I'm not able to find a way to do so for "comp.tex.tex". I've seen the TUG listinfo page (tug.org/mailman/listinfo), and I can find many of those, though not all in the nttp server "news.gmane.org". "comp.tex.tex" is not even in this page, and is linked as a google group. Any handy pointers to which server I should subscribe to?

@DavidCarlisle motivation is to be a tiny bit faster than \@ifdefinable or \@ifundefined for macros which are already constructed.

@MarcelKrüger I'm aware of those limitations, but thanks for reminding me.

@MarcelKrüger Unless somebody does \def\undefined{defined} ;-)

@egreg but that was assumed to not be the case in my question. Of course \ifdefined is better.

Is this still the best way to deal with a bunch of related "numbered" commands?

I get mildly terrified when I see things like \csname and \expandafter, so just asking.

@DavidCarlisle ^^^ any objections? ;-)

@marmot not prime

@DavidCarlisle Yes, we had this before. Wrong number range for a paliprime.

@FaheemMitha yes or avoid numbers

@marmot tough

@DavidCarlisle You only have a bit more than 500k to go.

@HaraldHanche-Olsen This look like an interesting project! They even have chocolate bars in my preferred percent range!

@marmot Very good and my compliment for.....111,111

@CarLaTeX Done! :-)I'm sorry about the question about a destination that wasn't removed right away. I deleted it. This day I do not feel well: I am with tachycardia, nausea, vomiting and with cervicalgia. I took a pill to be able to respond a bit to everyone. Thank you.

@Sebastiano I wish you feel better soon.

@StefanKottwitz Thank you. I cried this afternoon and tonight. It's happening to me every weekend. Even now I cry. Maybe I'm tired but today in Sicily everyone was on the beach with 23 degrees and I was with a scarf in my neck. This afternoon I went to bed. I recovered a bit but nothing. I also took some magnesium and potassium. Probably only the small pill of aceclofenac made me feel little better. But my head still turns and I'm going to go to bed in a while. It's 23:49 here.

@StefanKottwitz My chest hurts too, maybe from intercostal problems. But often, either because of anxiety or otherwise, I get strong beats.

@StefanKottwitz I'm taking up duty at school tomorrow. I wish you a peaceful rest and good work. Often I don't even know what I write :-( Very cordial greetings.

@Sebastiano Take time for yourself. Good weather will come again. Don't worry about anxiety or feeling pressure from other people, many just think about themselves and actually are not interested personally much in others who they don't know personally or as friends. 90% worries what others may think badly is like 1% what those others actually care about thinking bad since it doesn't touch them personally anyway.