What is the significance of Epsilon here? Elementary analysis

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The discussion focuses on the definition of convergence for sequences, specifically how a sequence (sn) converges to a real number s using the epsilon (ε) criterion. It explains that for every ε > 0, there exists a number N such that for all n > N, the absolute difference |sn - s| is less than ε. This concept is analogous to the epsilon-delta definition used for functions as x approaches a finite limit, but here it applies as n approaches infinity. The conversation emphasizes understanding the meaning behind the definition rather than just applying it in problems. Clarity on this concept is crucial for grasping the fundamentals of convergence in analysis.
retspool
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So i am almost 3/4 through elementary analysis but i seem to be unable to comprehend the basic definition of convergence of series

this is how the defn goes.

A sequence (sn) is said to converge to a real number s provided that

for each ε > 0 there exists a number N such that n>N implies |sn - s| < ε

where lim Sn = s where Sn approaches infinity
I am able to use this definition in the homeworks and problems, but i don't know what it means.

-retspooL
 
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welcome to pf!

hi retspool! welcome to pf! :smile:

(have an infinity: ∞ and try using the X2 icon just above the Reply box :wink:)

i assume you're happy with the epsilon-delta method for a function f(x) as x –> a where a is finite?

this is the same, except that instead of x -> a we have x -> ∞, and instead of "nested" neighbourhoods of a getting arbitrarily close to a, we have "nested" neighbourhoods of ∞ getting arbitrarily close to ∞, ie neighbourhoods of the form (N,∞) …

for any ε, we can find an interval (N,∞) in which |f(x) - s| < ε :smile:
 
Gotcha,

Thanks
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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