I'm trying to show a function has non-uniform continuity

In summary, the function f(x) = x^3 can be shown to have non-uniform continuity by choosing two sequences x_n = 1/n and y_n = 1/n^2, which both converge to zero. This satisfies the conditions of |(xn) - (yn)| approaching zero and |f(x_n ) - f(y_n)| approaching a real number.
  • #1
rbzima
84
0
I'm trying to show a function has non-uniform continuity, and I can't seem to think of 2 sequences (xn) and (yn) where |(xn) - (yn)| approaches zero, where f(x) = x3. Can anyone think of two sequences?
 
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  • #2
Where are the two sequences x_n and y_n separately supposed to converge?
 
  • #3
sutupidmath said:
Where are the two sequences x_n and y_n separately supposed to converge?

|x_n - y_n| need to converge to 0.
|f(x_n ) - f(y_n)| needs to converge to some real number, where f(x) = x^3
 
  • #4
I don't know if i am getting you right, but if there are no additional conditions imposed there, then i think the following would work

[tex]x_n=\frac{1}{n}[/tex] [tex]y_n=\frac{1}{n^2}[/tex] these both converge to zero and also

let [tex] |a_n=x_n-y_n=\frac{n-1}{n^{2}}|-->0, \ \ as \ \ n-->\infty[/tex]

Also:

[tex]|f(x_n)-f(y_n)=\frac{1}{n^{3}}-\frac{1}{n^6}=\frac{n^3-1}{n^6}|-->0, \ \ as \ \ \ n-->\infty[/tex]
 

What does it mean for a function to have non-uniform continuity?

Non-uniform continuity means that there are points in the function's domain where the function is not continuous and therefore breaks the definition of continuity. This can occur in functions where there are abrupt changes or discontinuities in the function's behavior.

How can I determine if a function has non-uniform continuity?

To determine if a function has non-uniform continuity, you can examine the function's behavior at different points in its domain. If there are any points where the function is not continuous, then the function has non-uniform continuity. You can also use the definition of continuity to check if the function satisfies the conditions for uniform continuity.

What is the difference between uniform and non-uniform continuity?

The main difference between uniform and non-uniform continuity is that uniform continuity requires that the function is continuous at every point in its domain, whereas non-uniform continuity allows for the possibility of discontinuities in the function's behavior at certain points.

Can a function have both uniform and non-uniform continuity?

No, a function cannot have both uniform and non-uniform continuity. A function can either be uniformly continuous or not, depending on whether it satisfies the definition of uniform continuity. If a function does not satisfy the conditions for uniform continuity, then it is considered to have non-uniform continuity.

Why is it important to show that a function has non-uniform continuity?

Showcasing that a function has non-uniform continuity is important because it helps to better understand the behavior of the function and where it breaks the definition of continuity. This information can be useful in analyzing and solving problems involving the function, and also in determining its limits and derivatives at certain points.

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