Math is hard. Apparently

[madbaker]

2010 is the start of a new year. It is not the start of a new decade. Nor was 2000 the start of a new millennium. You start a new cycle with year 1, not year 0.

To pre-empt the "If that's how people use it, it's correct" argument, I offer this riddle:

Q: "How many legs does a dog have if you call a tail a leg?"
A: "Four. Calling a tail a leg does not make it one."

What I'm reading: Ken Scholes, Canticle

Comments

[antoniseb.livejournal.com]

Centuries start on the year one, but decades are merely any stretch of ten years. So, if I say "The Sixties" I am referring to a ten year span. Is 1970 one of "The Sixties"?

[madbaker.livejournal.com]

By that logic a new decade starts every year. Or every day, minute, or second.

[antoniseb.livejournal.com]

And so it does... but my greater point is that it is convenient to refer to the years 1980 through 1989 as "The 80's", and call it a decade.

[madbaker.livejournal.com]

No.

Count to ten: 1, 2, 3... 10.

[madbaker.livejournal.com]

Convenient perhaps, but still wrong.

[aimeric.livejournal.com]

No computer scientist starts with 1! (okay, unless you're programming in old versions of Fortran). Arrays/etc are 0-indexed.

It always bugs the hell out of me that there is no year 0. It does mean that the last decade BC is 10BC - 1BC and the first decade is 1AD - 10AD (instead of 10 - 1BC, then 0-9 AD). Personally, though, I really, really, *REALLY* wish the latter was the system we used.

Still, if you take AD literally, then we're stuck. 1AD is indeed the first Year of (someone's) L-rd.

Of course, if one terms a decade as any 10 years, then one can get away with it to some extent...but the 1st Decade of (someone's) L-rd is still, by definition, 1AD to 10AD.

(now if we could just change AD to "Number of Years After the Birth of (someone's) Lord", then we could number starting from 0, and I'd feel MUCH better)

(actually, if I want to get *REALLY* pedantic, one could *still* define the 1st Year of (someone's) Lord as 0. Ordinals and Cardinals do not have to match. If I have a sequence 0,1,2,3...9, then 0 is the 1st number, so 0 is the 1st year of (someone's) Lord. But no one listens to me anyway...)

[goldenstag.livejournal.com]

But computer scientists aren't people ... have you ever eaten with one? (Oh yeah, you are one ...) heh.

Working with different programming languages can get weird, as some start counting at 1, some start at 0 ... (January = month 0 ... that takes some getting used to).

Playing Devil's Advocate

[aimeric.livejournal.com]

(first, note that I agree that, under current definitions, the "1st decade of the 21st century" is 2001 - 2010)

Consider:
How many days are in a year? Depends on the year. In some cases, 365. In others, 366.

So how many years are in a decade? Why not define the 1st decade as 1-9 and everything else AD as xxx0 - xxx9?
(of course, the last decade BC is still 10 - 1 BC, so people will still complain).

Of course, a counter to this is that a year is defined the way it is to prevent the drifting of the seasons, because the earth does not circle the sun in an integral number of days. The constraint is therefore based on the physics. No such constraint exists with the definition of decade, and besides, "decade" means 10 (my counter to the last is that December isn't the 10th month anymore, either).

(Of course, I still want a Year 0, dammit! Then again, I might as well ask for a Jan 0 as well, while we're at it, which I suspect wouldn't go over so well)

And regarding your riddle, I have a LONG response to that, which I'll save for a separate post. (short response: I know the intent, but the phrasing is ambiguous in at least a couple of respects, so there are multiple possible answers. If you want a single answer, phrase the question unambiguously. Then again, I suspect that the point of posing the riddle is a presumption that there is only one correct interpretation, so that actually restating it unambiguously destroys its use as a riddle :) )

[aimeric.livejournal.com]

Not quite.

"The 1990's" means "four-digit years beginning with 199". They span 10 contiguous years, so they are a decade.

This is not the same as "The last decade of the 20th century", which is 1991-2000.

Decade is just 10 contiguous years. If I say "I've worked at this place for a decade", I mean 10 years since my first day on the job.

[madbaker.livejournal.com]

I want a Year 0 as well.

[aimeric.livejournal.com]

Then again, if one says "2009 is the last year of the decade", then the statement is ambiguous. However, while they could mean either "the last year of the 00's", or "the last year of the 1st decade of the 21st century", the phrasing suggests the latter (since the former doesn't even use the word decade). In which case, as originally stated, the statement is indeed incorrect.

(I'm sorry, I've been having too much fun with this thread)

[madbaker.livejournal.com]

But then you get into the confusing issue where 10 decades do not coincide with a century.
In bond terminology, going from a price of 99 to a price of 100 is known as a "change of handle". Going from 2009 to 2010 is a change of handle but it's not a change of decade. Except as noted above where a change of decade is a continuous (and therefore meaningless for any precision) process.
Barbie's Dictum: Math is Hard.

[the-cheese-lady.livejournal.com]

Were you listening to Ronn Owens this morning too? :)

And, yes, you and I agree.

[aimeric.livejournal.com]

"But then you get into the confusing issue where 10 decades do not coincide with a century."

Again, it depends. One century is 100 years, therefore 10 decades.

If you say 20th century AD, then they consist of 1901-1910, 1911-1920, ..., 1991 - 2000.

If you say "the 1900's", then they consist of the 00's, the teens, the twenties, the thirties (1930 - 1939), etc. Again, 10 decades in one century, but this is not the same as the 20th century AD (1900 is not part of the 20th century; nor is 2000 part of the 1900's).

All of which still comes down to what is meant when someone says "the last year of this decade". By itself, it's meaningless unless you establish the context. Though we'd probably agree that this is probably shorthand for "the last year of the 1st decade of the 21st century AD"...in which case your original gripe is absolutely correct.

My problem is that the current AD numbering system is confusing, since, as you've pointed out, in our current system, "change of Decade AD" != "change of handle". But if one were to change/create a new system using xxx0 - xxx9, one runs into thorny issues when trying to address the years around 10BC - 10AD. (is there a year 0? If so, which Decade is it in? Or is it in *two* different Decades [-9 to 0, 0 to 9]? Or neither?)

The current system has the virtue of being symmetrical around the pivot point, but you lose a year, so time calculation is a little annoying: while Jan 1 1AD to 5AD is 4 years, Jan 1 2BC to 5AD is 6 years, not 7. Plus the annoying non-change-of-handle-vs-decade issue.

Personally, I'd prefer using C-type remainders: a decade begins if (year mod 10) == 0. So -10 to 1 is a decade, as is 0 to 9. In this system, a decade always begins in a year that ends in a 0.

True, under this scheme, "change of handle == change of decade" only if the year is >=0. But anyone dealing with BC has to deal with odd calculations anyway (see above), as does anyone who has to deal with the 11-day jump in the 1582 Gregorian calendar. I'd rather have the asychronicity if it most calculations easier. If there's no simple uniform solution in engineering, it's often advantageous to make the common case fast rather than introduce a general solution with greater complexity.

Still, regardless of any scheme I'd prefer, it does annoy me that many people don't understand the current scheme. Which is probably a very long, roundabout way of saying that I agree with you :)

[madbaker.livejournal.com]

The riddle is attributed to Abraham Lincoln. I don't usually listen to the radio; I was just feeling ranty when I posted this.

[fionnbharro.livejournal.com]

I came to the post late (just now, as a matter of fact), and I agree with you, wholeheartedly.

Thanks for the rant; it's one of my pet topics.

[fionnbharro.livejournal.com]

You don't play football, do you (I mean the 'American' kind -- not soccer)?

There's a fifty-yard line right smack-dab in the middle of the field, with a 49-yard line on either side.

Now; contrast this with Canadian Rules American Football.

See? See?!!?