Square of Dirac delta function

In summary, the question is whether the square of a Dirac delta function, ##(\delta(x))^2##, is still a Dirac delta function, ##\delta(x)##. The conversation discusses this topic and explores the idea that the squared function may be a multiple of the original function with a larger area under the graph. However, WolframAlpha shows that this is not the case and the correct answer is that the squared Dirac delta function is not defined. The conversation also mentions the concept of separating generalized functions into "smooth" and "singular" parts.
  • #1
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Is the square of a Dirac delta function, ##(\delta(x))^2##, still a Dirac delta function, ##\delta(x)##?

A Dirac delta function peaks at one value of ##x##, say 0. If it is squared, it still peaks at the same value, so it seems like the squared Dirac delta function is still a Dirac delta function, ##\delta(x)##, or some multiple of it, ##k\delta(x)##, where ##k>1##, since the area under graph seems larger.

How about the square root of a Dirac delta function?
 
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  • #2
It is something totally different than just multiplying by a constant.One thing to think about. The Del function is sometimes described as a rectangle of width d, and height (1/d) then take the limit as d->0. (so height approaches infinity)
At all values of d, you get an area of (d/d) = 1. But if you have (Del)^2, the width is essentially the same as Del, but the height is infinity^2 ?

WolframAlpha produced a surprising result for this. http://www.wolframalpha.com/input/?i=(DiracDelta[t])*(DiracDelta[t])
 
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  • #3
The Dirac delta "function" is defined by its behavior inside an integral: ∫f(x)δ(x)dx = f(0). It is a generalized function, not a function.
I think that your comment about an increased area of δ2 is confusing the delta function with an approximation of the δ function.
One approach to multiplying generalized functions is to separate them into their "smooth" and "singular" parts. In that, δ(x)2 = 0. (see https://en.wikipedia.org/wiki/Generalized_function#Algebras_of_generalized_functions)
 

1. What is the Square of Dirac delta function?

The square of Dirac delta function is a mathematical function that represents a point mass or impulse at the origin, with a value of infinity at the origin and zero everywhere else. It is also known as the squared delta function or the impulse response function.

2. How is the Square of Dirac delta function defined?

The Square of Dirac delta function is defined as the product of two Dirac delta functions: δ(x)*δ(x). This results in a function that is zero everywhere except at the origin, where it is infinity.

3. What is the significance of the Square of Dirac delta function in physics?

The Square of Dirac delta function is commonly used in physics to describe the response of a system to an impulse or point force. It is also used in signal processing and quantum mechanics to represent the state of a particle at a specific position.

4. How is the Square of Dirac delta function graphically represented?

The Square of Dirac delta function is graphically represented as a spike at the origin, with a value of infinity. It is often depicted as a square, hence the name, to differentiate it from the regular Dirac delta function, which is represented as a single spike.

5. What are the properties of the Square of Dirac delta function?

The Square of Dirac delta function has several properties, including symmetry (δ(x)*δ(x) = δ(-x)*δ(-x)), linearity (δ(a*x) = 1/|a|*δ(x)), and scaling (δ(ax) = 1/|a|*δ(x)). It also follows the sifting property, which states that the integral of the Square of Dirac delta function over any interval containing the origin is equal to 1.

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