Can e be accurately calculated using the limit definition?

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Discussion Overview

The discussion centers around the evaluation of the limit definition of the mathematical constant e, specifically through the expression lim (1 + 1/n)^n as n approaches infinity. Participants explore various methods of evaluating this limit, including the potential use of L'Hôpital's rule, and relate the concept to applications in finance, particularly in the context of compound interest.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant questions the possibility of evaluating the limit definition of e and expresses curiosity about rearranging the limit for evaluation using L'Hôpital's rule.
  • Another participant provides a detailed derivation using logarithms and L'Hôpital's rule, concluding that Y = e.
  • A participant mentions their interest in the connection between e and compound interest, particularly in hypothetical scenarios involving a 100% effective interest rate.
  • Discussion includes a reference to historical instances of high inflation rates in certain countries, suggesting that extreme financial conditions can challenge standard approximations.
  • Another participant adds to the discussion by referencing Zimbabwe's current economic situation as a parallel to the previous point about inflation and financial calculations.
  • A participant shares a link to an article discussing the Annual Percentage Yield (APY) for continuous compounding, noting that it indicates growth will be some multiple of e, although it does not solve the limit directly.
  • There is a mention of a lack of similar analyses regarding consumer price indices, indicating an area of interest for further exploration.

Areas of Agreement / Disagreement

Participants express varying degrees of interest in the mathematical evaluation of e and its applications, but there is no consensus on the methods or implications discussed. The conversation includes both mathematical reasoning and practical financial considerations, with no definitive agreement on the best approach to evaluating the limit.

Contextual Notes

Some discussions involve assumptions about financial scenarios that may not be realistic, and the mathematical steps presented may depend on specific interpretations of limits and logarithmic properties. The exploration of e's applications in finance introduces additional complexities that are not fully resolved.

cmcaulif
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Is it possible to evaluate the limit definition of e:

lim (1+1/n)^n ?
n->INF

I have seen approximations using binomial theorem, but I am curious as to if the limit could be rearranged and evaluated using L'hopital for instance.

thanks
 
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Sure

[tex]Y=\lim x\rightarrow\infty (1 + 1/x)^x[/tex]
[tex]\ln Y = \lim x\rightarrow\infty (x * ln(1 + 1/x))[/tex]
[tex]\ln Y = \lim x\rightarrow\infty (\frac{ln(1+1/x}{x^{-1}})[/tex]
Apply L'Hopital
[tex]\ln Y = \lim x\rightarrow\infty(\frac{\frac{-1}{x^2}}{1+1/x} * \frac{1}{\frac{-1}{x^2}})[/tex]
[tex]\ln Y = 1[/tex]
[tex]Y = e[/tex]
 
cheers, that helps a lot.

I was reading about compound interest and continually compounded interest(APY) and e kept on coming up, and specifically this expression if the effective interest rate is at 100%(obviously won't occur in real life, but very interesting for study).
 
"... obviously won't occur in real life ..."

Well, not so long ago (say 10yr) inflation and exchanges rate variations in some east-European countries (like Poland) were extremely high. Financial calculations at that time could not rely on approximations!
 
^ or Zimbabwe right now.
 
'Well, not so long ago (say 10yr) inflation and exchanges rate variations in some east-European countries (like Poland) were extremely high. Financial calculations at that time could not rely on approximations!'the article I was reading only dealt with APY:

http://members.optusnet.com.au/exponentialist/Calculating%20the%20Annual%20Percentage%20Yield%20(APY)%20For%20Continuous%20Compounding.htm

but it shows that the limit to the growth at any interest rate will be some multiple of e(though it just used an excel sheet of calcs instead of actually solving the limit).

I haven't seen anything like this regarding a consumer price index, though that would be interesting too.
 
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