Integrability of Sinusoidal Function on [-1, 1]: Finding L(f, P) and U(f, P)

In summary, the problem asks to determine if the function f(x) = sin(1/x^2) on [-1, 1] is integrable, with the exception of x = 0 where it takes on the value a. The difficulty lies in finding the upper and lower partitions, as the function oscillates significantly. However, it is possible to show that the function is Riemann integrable outside of any interval [-\epsilon, \epsilon], and then use theorems to show that you can choose partitions inside that interval that approach 0 as ε approaches 0.
  • #1
neom
13
0
The problem states:

Decide if the following function is integrable on [-1, 1]

[tex]f(x)=\left\{{sin(\frac1{x^2})\;\text{if}\;x\in[-1,\;0)\cup(0,\;1]\atop a\;\text{if}\;x=0}[/tex]

where a is the grade, from 1 to 10, you want to give the lecturer in this course

What I don't understand is how to find L(f, P) and U(f, P) since when I look at the graph of the function it oscillates a lot. So how do I choose the partition. It seems I would need an infinite partition almost to make it work. Or is there another way to do it?

Any help would be much appreciated as I am really lost on this problem.'

Edit: Sorry for the function not showing properly, don't know what I did wrong there

Should be

[tex]sin(\frac1{x^2})\;\text{if}\;x\in[-1,\;0)\cup(0,\;1][/tex]
&
[tex]a\;\text{if}\;x=0[/tex]
 
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  • #2
Showing something is Riemann integrable doesn't mean you have to choose partitions. You probably have some theorems that you can use to show f(x) is Riemann integrable outside of any interval [itex][-\epsilon,\epsilon][/itex]. Now show you can choose upper and lower partitions inside that interval that approach 0 as ε approaches 0.
 

FAQ: Integrability of Sinusoidal Function on [-1, 1]: Finding L(f, P) and U(f, P)

What is Riemann integrability?

Riemann integrability is a mathematical concept that measures the ability to find the area under a curve using a specific method called the Riemann integral. It is a fundamental concept in calculus and is used to solve various mathematical problems.

What are the conditions for a function to be Riemann integrable?

A function is Riemann integrable if it is bounded and continuous on a closed interval. This means that the function must have a finite limit at every point within the interval and must not have any vertical asymptotes.

What is the significance of Riemann integrability?

Riemann integrability is important because it allows us to compute the area under a curve, which has numerous applications in mathematics, physics, and engineering. It also serves as a foundation for more advanced integration techniques.

What is the difference between Riemann integrability and Lebesgue integrability?

The main difference between Riemann integrability and Lebesgue integrability is the approach used to find the area under a curve. Riemann integration divides the area into small rectangles, while Lebesgue integration divides the area into smaller, more uniform subintervals.

Can all functions be Riemann integrable?

No, not all functions can be Riemann integrable. For a function to be Riemann integrable, it must meet certain conditions, as mentioned in the second question. Functions that do not meet these conditions, such as those with vertical asymptotes, are not Riemann integrable.

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