What is the basis for the inner product of functions?

In summary, the inner product of two functions f(x) and g(x) can be represented by the integral \int_{a}^{b} f(x)g(x)dx. This integral satisfies the properties of an inner product and can also be extended to include a positive integrable function. More information on the basis of this inner product can be found at the link provided.
  • #1
sid_galt
502
1
What is the proof that the inner product of two functions f(x) and g(x) is

[tex]
\int_{a}^{b} f(x)g(x)dx
[/tex]

Or is this actually a definition of the inner product for functions? If it is a definition, then what is it based on?

Thank you
 
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  • #2
You've gotten it backwards:
That particular integral can be shown to fulfill the PROPERTIES OF AN INNER PRODUCT.

For your info, if w(x) is a positive integrable function, the following can also be shown to be an inner product:
[tex]<f,g>\mid_{w}=\int_{a}^{b}f(x)g(x)w(x)dx[/tex]
 
  • #3

1. What is an inner product of functions?

An inner product of functions is a mathematical operation that takes two functions and produces a scalar value. It is similar to the dot product of two vectors, but instead of operating on vectors, it operates on functions. It is often used in functional analysis and is a fundamental concept in modern mathematics.

2. How is the inner product of functions calculated?

The inner product of functions is calculated using the formula:

⟨ f, g ⟩ = ∫ f(x)g(x) dx

where f and g are two functions and the integral is taken over the entire domain of the functions. This formula may vary depending on the specific inner product space being used.

3. What is the significance of the inner product of functions?

The inner product of functions has many important applications in mathematics, physics, and engineering. It allows us to measure the similarity between two functions, find the length of a function, and define orthogonality between functions. It is also used to define important concepts such as inner product spaces, orthogonality, and projections.

4. Can the inner product of functions be negative?

Yes, the inner product of functions can be negative. This can occur when the functions have different signs over certain intervals, resulting in a negative value when integrated. However, in some cases, the inner product may be defined to always be positive, depending on the specific inner product space being used.

5. What is the geometric interpretation of the inner product of functions?

The geometric interpretation of the inner product of functions is similar to that of the dot product in vector spaces. It measures the angle between two functions and can be used to define orthogonality and projections. It can also be used to find the distance between two functions, similar to how the magnitude of a vector is used to find its length.

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