Can you Call this a standard limit?

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Discussion Overview

The discussion revolves around the limit expression lim x->0 sin(nx)/x = n for real numbers n. Participants explore its validity, derivation, and whether it constitutes a novel discovery or a known result in calculus.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant claims that lim x->0 sin(nx)/x = n is valid and has not seen it in textbooks.
  • Another participant provides a derivation using the substitution y = nx, leading to the conclusion that the limit equals n.
  • Some participants argue that the limit is a trivial corollary of the standard limit lim x->0 sin(x)/x = 1.
  • A participant expresses frustration over being accused of claiming a discovery, asserting that their approach is more efficient.
  • Several participants challenge the notion of originality, stating that the limit has been encountered by many students and appears in various calculus textbooks.
  • One participant emphasizes that simply writing down a limit that has not been explicitly stated does not constitute a significant discovery.
  • Another participant argues that the limit is not trivial and suggests that it is superior to the standard limit.
  • Some participants express concern over perceived hostility in the discussion, emphasizing the importance of open-mindedness in scientific discourse.

Areas of Agreement / Disagreement

Participants generally disagree on the originality of the limit and whether it represents a significant mathematical discovery. Multiple competing views remain regarding its status as a standard limit.

Contextual Notes

There are references to various calculus textbooks and online sources, indicating that the limit may be known in some contexts, but the discussion remains focused on the participants' differing perspectives on its originality and significance.

ZeroPivot
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lim x->o sin(nx)/x = n for n E real numbers

i haven't seen it in any books but it works.
 
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If we put ##y = nx##, then the limit is equivalent to
$$\lim_{y \rightarrow 0} \left( \frac{\sin(y)}{y/n}\right) = \lim_{y \rightarrow 0}\left( n \frac{\sin(y)}{y}\right) = n \left(\lim_{y \rightarrow 0} \frac{\sin(y)}{y}\right)$$
The limit inside the parentheses on the right hand side is standard, equal to ##1##. (Proof?)
 
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ZeroPivot said:
lim x->o sin(nx)/x = n for n E real numbers

i haven't seen it in any books but it works.
It can be derived from this limit:
$$\lim_{x \to 0}\frac {sin(x)}{x} = 1$$

$$\lim_{x \to 0}\frac{sin(nx)}{x} = \lim_{x \to 0}\frac{n \cdot sin(nx)}{nx} $$
$$= n \lim_{u \to 0}\frac{sin(u)}{u} = n\cdot 1$$
 
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so I am a genuise right for inventing it?
 
ZeroPivot said:
so I am a genuise right for inventing it?
Usually, potential candidates for the Fields Medal must wait to see if it is awarded to them. :smile:
 
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ZeroPivot said:
so I am a genuise right for inventing it?
I've seen this problem in several calculus books, so I think you're premature in saying that you invented it.
 
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Mark44 said:
I've seen this problem in several calculus books, so I think you're premature in saying that you invented it.

problem yes, but general standard solution no. they just say lim x->o sint/t = 1
my way is far more efficient.
 
Since it has appeared as a problem in many textbooks, thousands upon thousands of students have worked it, so you can't say you invented something that many people have done before you thought of doing it.
 
Mark44 said:
Since it has appeared as a problem in many textbooks, thousands upon thousands of students have worked it, so you can't say you invented something that many people have done before you thought of doing it.

many people have done many things but since i have not seen anywhere

lim x->o sin(nx)/x = n

you can say that I invented it. its like you know dancing many people could have foxtrotted but its the person that calls it foxtrot and creates a perimeter of foxtrot he/she is the inventor.

The GREAT thing about my standard limit is that its FAR superior to the wellknown standard limit that is lim x->0 sinx/x = 1 this is far inferior to my limit.
 
  • #10
It is not "your" limit. It is a completely trivial corollary.
 
  • #11
arildno said:
It is not "your" limit. It is a completely trivial corollary.

show me where lim x->0 sin(nx)/x = n is written?

i feel a lot of hostility here i don't know why, i thought this forum was about comradery and discussing ideas about science without persecution.
 
  • #12
Zero, just because you write something down which has not been literally word for word written down doesn't mean it is a great discovery that you have made. Anybody who has a solid understanding of calculus would have been able to calculate your limit immediately upon seeing it.

Furthermore, not that it's terribly relevant, but your result is stated in this here yahoo answer:
http://answers.yahoo.com/question/index?qid=20090919181027AADfJkR
lim x->0 sin(nx)/nx = 1

A genuine mathematical discovery is when you can answer a problem that people have been unable to answer before; answering a problem that people simply haven't bothered to write down before isn't a discovery, it's just applying some math to a problem.
 
  • #13
We are disputing your claim that you "discovered" something that has appeared in print for many years. I don't have any calculus textbooks with me right now, but I'll bet you could find this in many of the books that are used in calculus courses, such as Thomas-Finney, Larson, and others.
 
  • #14
Ok we have a lot of haters here today.

All I am saying is that the standard limit: lim x->0 sin(nx)/x = n is FAAAAAAR superior than lim x->0 sin(x)/x = 1
its not trivial at all. the yahoo link provided above is not my Standard Limit and its not as simple and elegant.

I think people here should be more open minded about discoveries you know a lot of scientist work so far they become nearsighted to great solutions and things do slip the system.
 
  • #15
ZeroPivot said:
Ok we have a lot of haters here today.
You are confused if you think what has transpired here falls under the category of "hate." No one has said anything of a personal nature about you. We have made valid points that contradict your claim of inventing something.
ZeroPivot said:
All I am saying is that the standard limit: lim x->0 sin(nx)/x = n is FAAAAAAR superior than lim x->0 sin(x)/x = 1
its not trivial at all. the yahoo link provided above is not my Standard Limit and its not as simple and elegant.
As already stated, "your" limit is well known, and is an easy corollary of the sin(x)/x limit.
ZeroPivot said:
I think people here should be more open minded about discoveries you know a lot of scientist work so far they become nearsighted to great solutions and things do slip the system.

Since you don't have any more to offer, I am closing this thread.
 

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