Is 2 a variable?
That, of course, is the joke.
Now, speaking as Moderator:
Alex_Dubinsky, personal insults are not permitted in this forum. Surely we can discuss a math joke without the need for words like “self-righteous” and “absolutism”? I have issued an Official Warning for this.
Expano: there’s no need to taunt him about it? (Just a friendly comment from me to you.)
This has always been my understanding of the joke. Actually, I heard it as “2 + 2 = 5 for large values of 2 and small values of 5.” This gets in both a reference to asymptotics and epsilonics of the sort often done in analysis. (E.g., sin(x) = x for small values of x.) (And yes, of course, part of the joke is that 2 and 5 are not variables.)
Quaere:
Are any of you here the originator of the statement? That is, are you the first person to have ever used it?
Unless you are that person, you cannot say what it means. You can only say what you thought it to mean when you used it, or when someone used it in your hearing.
When I first heard it, many, many moons ago, it was in the context discussed in the column by Dex. md200, I’m not saying your interpretation is wrong, but how long ago did you first hear/use the comment? It is quite possible that by the time you used it, someone had interpreted it to mean what you are saying, rather than the somewhat simpler meaning indicated by Dex. Or it could be the other way around, though it appears that, in writing the column, Dex researched the meaning, and presumably would have found evidence of such a migration.
For the same reason, I submit Exapno Mapcase cannot make his claims with any degree of confidence either.
You are correct, DSYoungEsq, we cannot be definitive without cites.
It is plausible that md2000 and Topologist are correct, that the joke arises out of the programming community and got cross-pollinated to the math community. I recall first hearing it in the '80s, and having to have it explained. Generally, when jokes have to be explained they are poor jokes, or not aimed at that audience.
Whereas if you are used to hearing statements with the disclaimer “for large/small values of x”, then that pattern would be an injoke clue.
Think of xckd comics, and how many people are puzzled by various items there, because the context is so injoke driven. I am reminded of one of my favorite punchlines, “assume a spherical chicken”, which is preposterously silly and makes no sense unless you are familiar with the penchant for certain types of problem analysis popular in engineering, i.e. making radical simplifying assumptions to allow a first principles approach, then look at the effects of the changes for the more complex case (if you get around to it).
That said, I fail to see a substantive difference between a programming origin and use relating to precision of estimations vs. computational precision, and a mathematical use relating to estimations and rounding in general. They both are related to the same phenomenon - the fact that values are effected by the precision with which they are computed.
I told you geek humor was not pretty…
I first heard the joke in university around 1983. It was a logical joke coming after several courses of computational math in the vein of “x=x+1 for sufficiently large values of x.” Maybe it flames up spontaneously every few years from the over-heating of student brain cells.
I found it a few years later in a collection of homemade buttons for sale - at a science fiction convention, I think. It included buttons of clever sayings like “Those who can, do; those who can’t, write the manual”.
So it’s an obvious joke around anyone who’s taken higher-level computational math or statistics courses. For sufficiently large values of a variable, the largest-exponent term determines the result.
Along the same lines are the jokes :
“There are 3 types of people in this world, those who can do math and those who can’t.”
“Crooks variable engineering constant, K - defined as Y=KX, where Y is the desired result and X is the observed reult. SImply apply K to the observed result to get the necessary result.”
“How different professions prove all odd numbers are prime -
Mathematician: 1 is prime, 1+2=3 is prime, 3+2=5 is prime, 5+2=7 is prime.
Therefore, by induction, all odd numbers are prime.
Physicist 1 is prime, 3 is, 5 is, 7 is, 9 - experimental error, 11 is prime, 13 is prime… see - all odd numbers are prime.
Engineer: 1 is prime, 3 is prime, 5 is prime, 7 is prime, 9 is prime, 11 is prime,… All odd number are prime.”
Guess which student discipline that last one made fun of?
See I told you geek humor was not pretty.
The problem being, of course, that 1 is not prime. :eek:
Computer engineer: 1 is prime, 3 is prime, 5 is prime head-twitch 5 is prime head-twitch 5 is prime head-twitch …
Total Tangent:
One of my favorite quiz questions, What comes next in the sequence 1, 3, 5, 7 …
(a) 9
(b) 11
© 8
All three answers can be correct.
(a) 9 is next in the sequence of odd numbers
(b) 11 is next in the sequence of odd prime numbers
© 8 is next in the sequence of numbers that have an “e” in their English spelling.
Which is why any good quiz/test discussing sequences asks for the formula for determining the nth term of the sequence described, rather than just asking for the next term.
ETA: Dex, since you’ve joined the discussion again, did your research suggest a possible date of origin of the joke?
I thought the joke went:
There are 10 types of people in the world, those that can do math, and those that can’t.
That would be, “There are 10 kinds of people in the world, those that understand binary, and those that don’t.”
Yeah, the binary one is a bit tooooo geek-humor.
There’s also less math, more irony:
“There are two types of people in this world - people who put everyone into categories, and those who don’t”.
And of course, there’s the physics joke about whether hell is exothermic or endothermic.
You can find it with google:
It ends (usually) with the comment that since XXXXX (some girl) had said that Hell would freeze over before she’d sleep with him, and he hadn’t gotten anywhere with her yet, hell must be exothermic.
All in all, too much physics humor - more funny because of the pseudoaccuracy of the logic.