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Sequence of discontinuous functions

  • Thread starter rapple
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  • #1
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Homework Statement


Need an example of a sequence of functions that is discountinuous at every point on [0,1] but converges uniformly to a function that is continuous at every point


Homework Equations





The Attempt at a Solution


I used the dirichlet's function as the template
f_n(x) = 1/n if x is rational and 0 if x is irrational

f_n(x) is discontinuous at every x in [0,1] and converges to f(x)=0

But this seems to be a erroneous analysis, because 1/n eventually goes to 0 so f_n(x) will be continuous as n->infinity

Can i get help in constructing this?
 

Answers and Replies

  • #2
Dick
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You already have a good example. What do you mean "because 1/n eventually goes to 0 so f_n(x) will be continuous as n->infinity". Can you give me an example of a value of n where f_n is continuous?
 
  • #3
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Can you give me an example of a value of n where f_n is continuous?
Since lim n->inf (1/n)=0, as n-> infinity, f_n(x) will be 0 for rationals as well.

which means that for any epsilon>0, if n is large enough, |f(x)-0|< epsilon for rational as well?
 
  • #4
Dick
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Less than epsilon, yes. Equal to zero, no. No f_n is equal to zero. Just because the limit is 0, that doesn't mean f_n becomes zero for any finite n.
 

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