Definition of asymptotic relation

In summary, the asymptotic relation between a function and a power series is defined as the limit of the difference between the function and the truncated power series approaching zero as x approaches the center point x0. This captures the idea of asymptoticity in that it shows how the power series approximates the function as x gets closer to the center point.
  • #1
hanson
319
0
Hi all!

Can anyone explain to me why the asymptotic relation between a function and a power series is defined in such a way:

For all N,

[tex]
f(x) - \sum_{n=0}^N a_n(x-x_0)^n << (x-x_0)^N
[/tex]

How does this incorporate the idea of asymptoticity?

Please kindly help.
 
Last edited:
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  • #2
hanson said:
Hi all!

Can anyone explain to me why the asymptotic relation between a function and a power series is defined in such a way:

For all N,

[tex]
f(x) - \sum_{n=0}^N a_n(x-x_0)^n << (x-x_{0})^{N}
[/tex]

How does this incorporate the idea of asymptoticity?

Please kindly help.
It means that:
[tex]\lim_{x\to{x}_{0}}\frac{f(x) - \sum_{n=0}^N a_n(x-x_0)^n}{(x-x_{0})^{N}}=0[/tex]
 
  • #3


The asymptotic relation between a function and a power series is defined in this way because it takes into account the behavior of the function as x approaches a certain value, typically denoted as x_0. The term "asymptotic" refers to the behavior of the function as it approaches a particular value, and this definition captures that by considering the difference between the function and the power series as x approaches a certain value.

The notation used, "<<" (much less than), indicates that the difference between the two expressions becomes increasingly smaller as x approaches x_0. In other words, the function and the power series approach each other in a way that is not equal, but the difference between them becomes insignificant as x gets closer to x_0. This is the essence of asymptoticity - the two expressions may not be exactly equal, but they behave similarly as x approaches a certain value.

Furthermore, the use of the summation symbol and the upper limit of N in the power series allows for a more precise definition of the asymptotic relation. By considering the sum of increasingly higher powers of (x-x_0), we can capture the behavior of the function at different orders of magnitude as x approaches x_0. This allows for a more comprehensive understanding of the asymptotic relationship between the function and the power series.

I hope this helps to clarify the definition of the asymptotic relation and how it incorporates the concept of asymptoticity.
 

1. What is the definition of asymptotic relation?

The asymptotic relation is a mathematical concept that describes the behavior of a function as its input approaches a certain value, usually infinity. It is used to compare the growth rate of two functions and determine if they are similar or different.

2. How is asymptotic relation different from equality?

Asymptotic relation is a looser form of comparison than equality. While equality requires two functions to have the same output for a given input, asymptotic relation only requires the functions to have similar growth rates. This means that two functions can be asymptotically related even if they are not equal.

3. What is the significance of asymptotic relation in mathematics?

Asymptotic relation is important in many areas of mathematics, including analysis, number theory, and graph theory. It allows us to compare the complexity or efficiency of different algorithms or functions, and make predictions about their behavior as the input size grows.

4. Can two functions have more than one asymptotic relation?

Yes, two functions can have multiple asymptotic relations. For example, if a function has a polynomial growth rate, it can be asymptotically related to all other polynomials with the same degree. It is also possible for a function to have no asymptotic relation with another function.

5. How is asymptotic relation denoted in mathematical notation?

The most common notation for asymptotic relation is the "big O" notation, which uses the symbol "O" followed by the function inside parentheses. For example, if f(n) is asymptotically related to g(n), it can be denoted as f(n) = O(g(n)). Other notations include the "little o" notation (smaller growth rate) and the "Theta" notation (equal growth rate).

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