Understanding the Delta Function: Integrating from -∞ to ∞

In summary, the delta function is a mathematical concept used to represent point sources or impulses in physics and engineering. It is defined as having infinite height and unit area at x = 0, with a value of 0 everywhere else. The delta function can be used for integration by breaking it down into two separate integrals and has applications in solving differential equations and calculating probabilities. It can also be used as a basis for representing other functions through delta function expansions.
  • #1
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My book loves to represent the delta function as:

δ(r-r')=∫-∞exp(i(r-r')k)dk

Now I can understand this formula if the integration was over the unit circle since. But this is an integration for which the antiderivative as no meaningful limit as x->±∞
 
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  • #2
The integral written is only true as formality. What's really going on is that Dirac is a tempered distribution, and hence has a Fourier transform. It can be shown that ##\hat\delta = 1##. What the equation is trying to say is that the Inverse Fourier of the constant 1 is Dirac delta.
 

Related to Understanding the Delta Function: Integrating from -∞ to ∞

1. What is the delta function?

The delta function is a mathematical concept that represents an infinitely tall and narrow spike centered at the origin. It is often used in physics and engineering to model point sources or impulses.

2. How is the delta function defined?

The delta function is defined as follows: δ(x) = 0 for all x ≠ 0 and ∫δ(x)dx = 1. In other words, it is zero everywhere except at x = 0, where it has infinite height and unit area under the curve.

3. How do you integrate from -∞ to ∞ using the delta function?

The delta function can be used as a tool for integration from -∞ to ∞ by representing it as a limit of a sequence of functions. This allows the integration to be broken down into two separate integrals from 0 to ∞ and from -∞ to 0, which can then be evaluated using the properties of the delta function.

4. What is the significance of integrating from -∞ to ∞ with the delta function?

Integrating from -∞ to ∞ with the delta function allows for the evaluation of integrals involving discontinuous or unbounded functions. It also has applications in solving differential equations and calculating probabilities in statistics and probability theory.

5. Can the delta function be used to represent other functions?

Yes, the delta function can be used as a basis for representing other functions through the concept of delta function expansions. This involves expressing a function as a sum of scaled and shifted delta functions, similar to a Fourier series representation.

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