explain xkcd - User contributions [en]

Talk:2697: Y2K and 2038

2022-11-14T13:43:36Z

141.101.107.157: ICYMI

Y2K issues solved back in 1996. Even wrote a letter to the Board of Trustees.
2038 Problems are not-my-concern. Retired 9/30/2022.[[Special:Contributions/172.70.110.236|172.70.110.236]]
:Many of the people who helped solve the Y2K problem were pulled out of retirement. Lots of the issues were in old COBOL software, and there weren't enough active programmers who were competent in COBOL. So keep your resume ready. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 20:07, 11 November 2022 (UTC)

this is so weird I just finished a research assignment on the Y2038 problem [[Special:Contributions/172.71.166.223|172.71.166.223]] 18:27, 11 November 2022 (UTC)

Somewhere there is an essay about the unexpected synergy between the Y2K bug and the burgeoning open source movement, which may or may not be useful for the explanation. [[Special:Contributions/172.70.214.243|172.70.214.243]] 20:18, 11 November 2022 (UTC)
:https://www.livehistoryindia.com/story/eras/india-software-revolution-rooted-in-y2k is a fascinating essay too. [[Special:Contributions/172.70.214.151|172.70.214.151]] 21:03, 11 November 2022 (UTC)
:I wouldn't be surprised if there's such an essay, but I suspect it's more of a coincidence. The late 90's was also when the Internet was really taking off, and that may be more of a contributor. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 23:04, 11 November 2022 (UTC)
::All involved what epidemiologists call coordinated or mutually reinforcing causes, IMHO. [[Special:Contributions/172.71.158.231|172.71.158.231]] 01:41, 12 November 2022 (UTC)

Speaking of which, what comes after Generation Z? Generation AA? ZA? Z.1? Help! [[Special:Contributions/172.70.214.243|172.70.214.243]] 07:24, 12 November 2022 (UTC)
:{{w|Generation Alpha}} [[Special:Contributions/172.69.34.53|172.69.34.53]] 07:27, 12 November 2022 (UTC)
::[[1962|Zuckerbergs Army.]] --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 15:18, 12 November 2022 (UTC)
:::The Legion of the Doomed [[Special:Contributions/172.70.162.56|172.70.162.56]] 10:20, 14 November 2022 (UTC)

I've been unable to confirm this so I'm moving it here: A major problem had struck IBM mainframes on and after August 16, 1972 (9999 days before January 1, 2000) that caused magnetic tapes that were supposed to be marked "keep forever" instead be marked "may be recycled now."{{Actual citation needed}} [[Special:Contributions/172.71.158.231|172.71.158.231]] 07:37, 12 November 2022 (UTC)

Does the arrow move over time? ... should it? (I think so!) It could be done server side and only regulars would [see, sic] that it changes over time. Then... perhaps we could see different versions of the strip cached on the Internet. --[[Special:Contributions/172.71.166.158|172.71.166.158]] 08:30, 12 November 2022 (UTC)
It isn't, of course, but if it was a .GIF with ultralong replace-cycles then only those who ''kept the image active'' would see the arrow move in real-time. (It would reset to ''now's'' "now" upon each (re)loading, so it would have an even more exclusive audience, aside from those that cheat with image(-layer) editing. ;) ) [[Special:Contributions/172.70.162.57|172.70.162.57]] 13:32, 12 November 2022 (UTC)

Should we mention anything about that it is that specific year in a specific calendar? As far as I know there was also {{w|Japanese_calendar_era_bug|fear of a similiar bug in Japan}} recently. However Wikipedia seems not to be up to date about it. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 15:18, 12 November 2022 (UTC)

Does anyone know of an actual program or OS that stored the year as two characters instead of a single byte? I have (and had back then) serious doubts that any problems existed. Even the reported government computers had people born prior to 1900 entered, so they already had to have better precision than "just tack on 1900." Even using a single signed byte would still have been good for another 5 years from now. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 17:22, 12 November 2022 (UTC)
:In my experience (I lived and worked through the Y2K preparations) it wasn't so much "an actual program", or necessarily a fundemental limitation of an entire OS (though the roots of the problem effectively date back to key decisions surrounding the developmet of the IBM System/360 in the 1960s), but a matter of how data was held in human-readable but space-saving format. Someone in the '70s (or even up into into the '90s) may have decided their system could store some date as the six characters representing DDMMYY (or ay of the other orders) secure in the knowledge that the century digits were superfluus - and would have perhaps sent the footprint of a standard record over some handy packable length for the system, say 128 bytes. Which was a lot in those days.
:(If the year ''value'' had been recorded in 16bit binary, or even 2x7bit or doubled 6-bit, it could have been as good for the computer, but ''oh the fuss'' to convert to and from a human-orientated perspective. And it worked neatly enough, right?)
:And a useful implementaion might be used, in some form or other for a long time... Sometimes the storage system is upgraded (kilobytes? ha, we have megabytes of space now!) and the software to handle it might be ported and even rewritten, but at each stage the extra data has to match the old program, and the new program has to read and write the current data, however kludged it actually is. And it works, at least under the care of those who dabble in the dark arts of its operation. And not many others are bothered or even have any idea of what ;ies beneath the surface.
:Until somebody starts to audit the issue and asks everyone to poke around and check things... Thenthings get sorted in-situ ''or'' a much needed (YMV!) change of process is swapped in, in the place of old and (possibly) incorrect hacks. [[Special:Contributions/172.69.79.133|172.69.79.133]] 20:00, 12 November 2022 (UTC)
::Sometimes the "savings" of storing data in a compact form are exceeded by the "cost" of having to convert it between the convenient-to-use form and the compact form. I used to work on a system that used 32-bit words for all data types: characters, shorts, longs. When we started running out of space, we "manually" packed our data, stuffing multiple shorts and bytes into words. But in some cases, the additional code needed to pack/unpack would have taken more space than what we'd have saved in the data, without even looking at the processing time cost. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 05:52, 13 November 2022 (UTC)
:The first computerised passport system for the UK had a y2K issue. In fact, it was designed in, because it was supposed to be replaced before 1999. Unfortunately, progress with its replacement was running late. We thought that we could get away with two digits for certain dates because the software was going to be thrown away before the end of 1999. And yes, two digit years were common in COBOL programs because decimal numbers coded using ASCII or EBCDIC were the default for numeric data. [[User:Jeremyp|Jeremyp]] ([[User talk:Jeremyp|talk]]) 15:32, 13 November 2022 (UTC)

:1. Having done programming since 1966, I know that much data was stored on 80-character cards (and way before that year and the IBM System/360) and using 2 characters (2.5% of the card) to store the "19" was not acceptable. As processes moved into the tape and disk world, human nature tended to not expand the field to 4 characters (the future is a long way off until, suddenly, it isn't). [[Special:Contributions/172.70.178.65|172.70.178.65]] 07:57, 13 November 2022 (UTC)
:: I wouldn't call punch cards a *real* Y2K problem. They had been replaced by then. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 18:55, 13 November 2022 (UTC)

:2. I actually saw a Y2K failure. It occurred at the beginning of 1999 when a job scheduling program scheduled a job for the year 1900 because it was always keeping the schedule active a year in advance. The scheduling software had actually been fixed but the upgraded version had not been installed yet, so there was no significant outage. [[Special:Contributions/172.70.178.64|172.70.178.64]] 08:02, 13 November 2022 (UTC)

''"an actual program or OS that stored the year as two characters"'' In years 2000-2002, it was common to see dates on web-pages showing as "19100". I/we always assumed the 19 was hard-coded, the 1-99 was a script, just concatenated. ''PRR'' [[Special:Contributions/172.70.130.154|172.70.130.154]] 06:52, 14 November 2022 (UTC)

"[https://www.explainxkcd.com/wiki/index.php?title=2697:_Y2K_and_2038&oldid=298667 I've never heard of anyone actually recompiling to a 33-bit integer format]" - that's not what was said, but it seems to be about programming so as to pack 33-bits of precision across (or within) whatever standard bit-boundaries the system normally provides for. Which is not so fanciful, and used to be a good creative coding practice, if done well. See 8x7bit to/from 8x7bit packing or unpacking (or as an in-transit stage), which was a regular requirement at one time (arguably still is, but mostly invisibly to the user, in the usually 6-bit rationalisation that is MIME). But the edit above doesn't preclude that interpretation, so just noting this here. [[Special:Contributions/141.101.107.157|141.101.107.157]] 13:43, 14 November 2022 (UTC)

Talk:2696: Precision vs Accuracy

2022-11-11T09:29:50Z

141.101.107.157:

87.532% of all statistics are just made up. [[Special:Contributions/172.70.178.220|172.70.178.220]] 11:10, 9 November 2022 (UTC)

Why is 'Barack Obama is 6'1"' and 'Barack Obama has 4 legs' medium precision? It seems to give exact value, so high precision. [[User:Tkopec|Tkopec]] ([[User talk:Tkopec|talk]]) 11:44, 9 November 2022 (UTC)
: OK, I get it. 6'1" means something between 6'0.50" and 6'1.49". For height it's OK, but when counting legs, it seems like a stretch. [[User:Tkopec|Tkopec]] ([[User talk:Tkopec|talk]]) 12:30, 9 November 2022 (UTC)
:: The four legs are probably considered to be only medium precise, not because of the number but because of the imprecise term "leg". While humans can walk on all four extremities, thereby using them as legs, the upper two are commonly referred to as arms. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 14:54, 9 November 2022 (UTC)
:: (ECed by Bischoff) Plus a person's height (excluding differences to footwear and perhaps hairstyle) varies by an inch or so over the course of a day, as the spine compresses whilst mostly upright (would depend a bit upon your daily activities, but "an inch" or 2-3cm is the typical quoted value, with all the questions about precision ''as well as'' accuracy). Within an inch of such a foot-and-inch value is basically between slightly over a percentage point of drift across a continuum of ultimately non-integer values.
:: The number of legs is ''generally'' a whole number (perhaps lower-limb amputees could claim "half a leg", but is that for above the knee or below or... that's beyond my wish to define, I would leave it up to the individual amputee to finesse to their own liking) and assigning decimals, even .000(recurring), would be ''over-''precise. A definite plain figure (however inaccurate) being the happy and acceptable medium between that and the vague imprecision (never mind inaccuracy) of the kind in the cell below. [[Special:Contributions/172.71.178.137|172.71.178.137]] 15:00, 9 November 2022 (UTC)
:::The medium is because it says most, and not all! --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 08:08, 10 November 2022 (UTC)
::::It says "most cats", indeed, but the above was about Obama, singular. Though I think it's covered anyway... [[Special:Contributions/172.70.85.25|172.70.85.25]] 09:44, 10 November 2022 (UTC)
:::::All the statements about 'Barack Obama' ought to be medium precision at best, because there could be more than one Barack Obama, and it doesn't give any further contextualisation to identify, for example 'the Barack Obama who was president of the United States of America'. [[Special:Contributions/141.101.107.157|141.101.107.157]] 09:29, 11 November 2022 (UTC)

Someone should add an explanation of the difference between precision and accuracy. [[User:Nutster|Nutster]] ([[User talk:Nutster|talk]]) 13:13, 9 November 2022 (UTC)
:Tried it myself. Maybe made it too compact, but I often go on too long so I tried made it as brief and snappy as I felt I could. Over to other editors to rewrite or replace. [[Special:Contributions/172.71.178.137|172.71.178.137]] 15:00, 9 November 2022 (UTC)
::That there is confusion over this was a bit of a surprise to me, about 20 years ago, when I worked (as I did for many years) in the outdoor pursuits trade. GPS units would give a 12-character grid reference (1m<sup>2</sup>), but couldn't be relied upon to that level. I would tell people they're more precise than they are accurate, until it became apparent that they were waiting for me to complete the joke they thought I'd begun, as I was so clearly contradicting myself, what with the two words meaning identical things.
::Having gone on to explain the difference between the words, the neat brevity I'd sought was lost.
::Obviously they can be used sort of interchangeably in casual conversation, but I thought the difference was well enough known that, when talking about a navigational instrument, it would be obvious what was meant.
::Nope. [[User:Yorkshire Pudding|Yorkshire Pudding]] ([[User talk:Yorkshire Pudding|talk]]) 20:18, 9 November 2022 (UTC)
:::I deal with OS Grid References a lot, in a similar context, and a number of people who give 10-digits or more (2x5, for 1m res) from devices that typically don't ever settle down to less than 3m, and provably can be tens of metres off if there happens to be a small tree or shrub nearby.
:::(In fact, the other day I was geohashing myself, and my device was insisting I was in a totally different bit of the open field, 50m or so, no matter how much I sat it down at the provably correct point and wandered away so that even ''I'' wasn't obscuring its view of the sky. But it was good enough for me, which was all I do it for, so after giving it 5 minutes I counted it as done.)
:::And, in yet another activity, the publicised information for an event included a 12ish-DP reference for the starting area (vaguer than that), but just the ''postcode'' for the HQ (a very definite building that you could bullseye on a map), in a rural area where it covered half the valley! [[Special:Contributions/172.70.86.12|172.70.86.12]] 22:19, 9 November 2022 (UTC)

How is 17.082 palindromic? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 14:54, 9 November 2022 (UTC)
:My error, I meant an anagram! (Was going for "anagramic", and my brain clearly rebelled.) [[Special:Contributions/172.71.178.137|172.71.178.137]] 15:00, 9 November 2022 (UTC)

High Precision High accuracy, Randall Munroe misses when Obama was president. Low precision Medium-rare accuracy, so do we, Randall, so do we. {{unsigned ip|172.70.130.154 }}

It is so annoying that the US uses . and , to mean the opposite of what most European countries (including Denmark where I live). So when I read this it states that Obama was president less than 3 days (70 hours) but it more than 70000 feet tall. :-) Of course I now the difference but I have to think about it more than if everyone used the same standard. Also height should use SI units as everyone should ;-) (weight given in number of cats is the new SI unit as far as I know, but don't use inches and feet ;-D ) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 08:17, 10 November 2022 (UTC)
:Well, as a UKian, I was happy enough. Tell you what, though, let's develop a [[927: Standards|new and mutually-acceptable standard notation]]... ;) [[Special:Contributions/172.70.85.25|172.70.85.25]] 09:44, 10 November 2022 (UTC)
::Good idea. Lets meet on [[2562|11/12/22]] to discuss the details. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 13:41, 10 November 2022 (UTC)

I think Randall missed an opportunity to clarify how high precision can make something inaccurate. He could have said that Obama is 6’ 1.02173” tall, which would clearly be very precise, and also clearly inaccurate, simply because of the excessive precision. [[User:John|John]] ([[User talk:John|talk]]) 15:22, 10 November 2022 (UTC)
:Saying 6'1.0278 would have been more in theme, there. And it would be not really more inaccurate (might even be closer to the truth...) but would convey a false precision.
:Interstingly, when Andrew Waugh measured Mount Everest (before it was so named) he got a diffraction-adjusted figure of 29,000 feet, but decided to announced that it was 29,002 so that it didn't just like a rough figure rounded to the nearest hundred or even thousand feet. This made him the first person to put two feet on the top of Everest!
:(...The actual error was not bad, given his measurements had to be made from hundreds of miles away. Current official measurements with on-the-spot modern GPS say 29,031.7 feet (for the snow-peak, which is all that Waugh could mention), after 170ish years of (by some estimates, but contested) about a foot of extra height per decade through the continuing techtonic raising of the Himalaya. And any unknown differences in snow-depth. Certainly it was within tens of feet, i.e. a dozen or so metres. With a bit of an error-bar, but not really that big when you consider it...)
: So, arguably, that case was a deliberately false accuracy to help convey the true precision. [[Special:Contributions/172.70.90.3|172.70.90.3]] 16:15, 10 November 2022 (UTC)

I was expecting maybe a reference to Schrödinger's President when I first read the comic - but later realized that this could have been misconstrued as a threat. Oops!