A question on sequence of functions.

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The discussion centers on the existence of a continuous function g: R -> R that is not periodic, yet allows for every sequence of real numbers {a_k} to produce a sequence of functions g_k(x) = g(x + a_k) with a uniformly converging subsequence on R. Participants propose various functions, including g(x) = sin(e^x) and g(x) = exp(-x^2), while examining the implications of the Arzelà-Ascoli theorem. Ultimately, the consensus suggests that functions like g(x) = sin(x) + cos(πx) exemplify the desired properties, as they are continuous, bounded, and exhibit equicontinuity.

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  • #31
ok, what about the question with which iv'e opened the thread?
 
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  • #32
loop quantum gravity said:
i thought a periodic function has a small period which is non zero, here clearly there isn't such period.
anyway, if this is considered a periodic function then back to the original question is there such a function which is not periodic?

I think NateTG's example sin(x)+cos(pi*x) is an excellent example of a function that statisfies your requirements (as are 'almost periodic' functions in general). How many times has that been stated on this thread? Can you prove it?
 
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  • #33
i think by arzela ascoli theorem i only need to show that it's uniformly bounded (obviously it is by: 2. and that this sequence of functions is equicontinuous, which is also bacause of the first derivative is uniformly bounded so it's equicontinuous.

ok, thanks Dick,Nate and also Matt, i appreciate your help on this question.
 

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