Measurable functions and division by zero

In summary, the conversation discusses whether the function g(t) = f(t)/t on [0,1] is measurable, given that f is measurable on [0,1] and that g agrees with the measurable function g_0 = g|_{(0,1]} almost everywhere. The conclusion is that g is indeed measurable on [0,1] despite the potential problem of division by zero at t=0, as g is defined on the whole interval [0,1] and there is nothing in the definition of measurable functions that prevents a function from being infinite.
  • #1
AxiomOfChoice
533
1
Consider the function [itex]g(t) = f(t)/t[/itex] on [itex][0,1][/itex], where [itex]f[/itex] is measurable on [itex][0,1][/itex]. Does it follow that [itex]g[/itex] is measurable on [itex][0,1][/itex]? I know there's a problem -- namely, division by zero -- only on a set of measure zero -- namely, [itex]\{0\}[/itex] -- and that [itex]g[/itex] agrees with the measurable function [itex]g_0 = g|_{(0,1]}[/itex] almost everywhere. So I'd think the answer is "yes," since I was under the impression that if two functions agreed almost everywhere, then if one was measurable, the other was too...but I thought that was only if the functions were defined on the same set, and [itex]g[/itex] and [itex]g_0[/itex] clearly are not.
 
Physics news on Phys.org
  • #2
There is nothing in the definition of measurable functions to prevent a function from being infinite.
 
  • #3
In other words, g is defined on the whole interval [0,1]:
[tex]g:[0,1]\to\overline{\mathbb{R}}[/tex]

taking the value [itex]\infty[/itex] at t=0.
(well, I don't know how f is defined, but at least if f if is everywhere finite this makes sense)
 

1. What are measurable functions?

Measurable functions are mathematical functions that assign a numerical value to every element in a given set. These functions are used to measure the properties and characteristics of a given system or phenomenon.

2. Why is it important to have measurable functions?

Measurable functions are important because they allow us to quantitatively analyze and understand complex systems or phenomena. By assigning numerical values to different elements, we can make comparisons, draw conclusions, and make predictions.

3. How is division by zero handled in measurable functions?

In measurable functions, division by zero is undefined. This is because division by zero leads to an infinite result, which is not a meaningful or useful value in most cases. Therefore, it is important to avoid dividing by zero in measurable functions.

4. Can measurable functions handle negative values?

Yes, measurable functions can handle negative values. In fact, many real-world systems and phenomena involve negative values, and measurable functions are designed to handle them. However, in some cases, negative values may not be relevant or meaningful, and it is up to the scientist to determine their significance.

5. What is the difference between a measurable function and a non-measurable function?

The main difference between a measurable function and a non-measurable function is that a measurable function assigns a numerical value to every element in a given set, while a non-measurable function may not. Measurable functions are useful for quantitative analysis, while non-measurable functions may be used for other purposes such as qualitative analysis or modeling.

Similar threads

Replies
1
Views
932
Replies
8
Views
2K
Replies
1
Views
956
Replies
3
Views
1K
Replies
12
Views
2K
Replies
1
Views
153
  • Calculus
Replies
2
Views
1K
Replies
2
Views
958
  • Calculus and Beyond Homework Help
Replies
1
Views
278
Back
Top