Talk:Limit (mathematics)

What about limits in R when you go from right and from left side of the point p? The general limit the article is talking about doesn't have to exist (e.g. lim_(x->0+)(ln(x)) can be calculated (0+ means from right) while lim_(x->0-)(ln(x)) isn't defined in R). INAM, but I think it should be explained in the article. Thanks.

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is it an "unbounded limit" or "limitless because it is unbounded"? Pizza Puzzle

To be honest, I'm not sure what you mean... If f(x) tends to infinity as x tends to c, then f(x) is unbounded in any neighbourhood of c. I would say that it has no limit, because infinity isn't really a "limit" as such... Unless, of course, you define it to be one... (cf. Dumpty, 1871) -- Oliver P. 21:29 3 Jun 2003 (UTC)

Well, what i mean, is that u changed this article to state that something had a "limit of infinity" - ill fix it. Pizza Puzzle

No, I didn't say anything about anything having a "limit of infinity". I did, however, say that a function can have a limit as its argument tends to infinity. Admittedly, what I added was not particularly well written, but it didn't say what you seem to think it said. -- Oliver P. 15:42 8 Jun 2003 (UTC)

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Removed this:

====A Brief Note Regarding Division by Zero====

In general, but not in all cases, should u directly substitute c for x (into f(x)) and obtain an illegal fraction with division by zero, check to see whether the numerator equals zero. In cases where such substitution results in 0 / 0, a limit probably exists; in other cases (such as 17 / 0) a limit is less likely. For instance; if f(x) = x³ + 1 / x - 1; then, if one substitutes 1 for x, one will obtain 2 / 0; the limit of f(x) (as x approaches 1) does not exist.

I can't be bothered to do the graph offhand, but there will be a limit: either + or - inf. User:Tarquin

oops Pizza Puzzle

Plus and minus infinity are not limits according to the definition in the article. Please make sure that you have some understanding of the article before you go removing bits. -- Oliver P. 15:42 8 Jun 2003 (UTC)

I'm not aware that infinity is a limit; because, infinity is not a real number and my understanding is that limits must be real numbers. Pizza Puzzle

Yes, that's what I just said. I said it in reply to your statement that "there will be a limit: either + or - inf". If you have changed your mind, and are retracting your previous statement, please replace what you removed from the article. -- Oliver P. 16:02 8 Jun 2003 (UTC)

No sir! I did not state that there will be a limit either + or - inf. The user who does not sign his messages stated that. I have added:

• the behavior of a function as its arguments get "close" to some point (or attempts to get close to infinity),

which I believe is what u are referring to above. There is now the question of, if the above user was wrong, does that mean I can reinsert my text:

• For instance; if f(x) = x³ + 1 / x - 1; then, if one substitutes 1 for x, one will obtain 2 / 0; the limit of f(x) (as x approaches 1) does not exist.

or would that be a hostile revert? He had initially removed the entire paragraph, which I put most of it back in, but I didnt put the final line back since there was a debate of sorts regarding it.

ACHTUNG SPITFEUER

• As x approaches 0, F(x) = 1 / x² is not approaching a limit as it is unbounded; a function which approaches infinity is not approaching a limit. Note that as x approaches infinity, F(x) = 1 / x² does approach a limit of 0.

Pizza Puzzle

Oh, I see! In that case, I apologise unreservedly for having accused you. I'll blame Tarquin for my error, though, since he was the phantom non-signer. ;) There is a problem in that there are different ways of defining what a limit is. I'll give the article some thought, and come back to it later. I wouldn't object to you putting that example back in, although you should leave out the idea of substitution; a limit only depends on the behaviour as you appraoch the point, not at the point itself. -- Oliver P. 16:15 8 Jun 2003 (UTC)

The subsitution point is, IF you substitute, and you get division by zero, if you get 0 / 0, then there is probably a limit, otherwise there probably isn't. Pizza Puzzle

Oh, I'll think about it later. I should be doing work... -- Oliver P. 16:29 8 Jun 2003 (UTC)

Now here, this text says (in so many words): "The limit, L of f(x), as f(x) increases (or decreases) without bound is an infinite limit. Be sure that you see that the equal sign in "L = infinity" does not mean that the limit exists. Rather, this tells you that the limit fails to exist by being boundless."

It would appear, that it is correct to refer to "infinite limits" but one should understand that an "infinite limit" is not a limit. See also: "unbounded limit" Pizza Puzzle

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Would it be too much to expect User: AxelBoldt[?] to explain some of his more "major" changes? It appears that a great deal of information was deleted. If he had a problem with it, it would have been more appropriate to discuss it or improve it; rather than merely deleting it. Pizza Puzzle