Exploring the Relationship between the Step Function and Dirac Delta Function

In summary, the conversation discusses the proof of the derivative of the step function, represented by the symbol θ(x), using the Dirac delta function. The solution involves recognizing that 1 - θ(x) is equivalent to the Heaviside step function and using this to simplify the problem.
  • #1
CasualDays
9
0
Derivative Using Dirac Delta Function

Homework Statement


Let [tex]\theta[/tex](x) be the step function:

[tex]\theta[/tex](x) be equivalent to

1, if x > 0
0, if x [tex]\leq[/tex] 0

Show that [tex]\frac{d \theta }{dx}[/tex] = [tex]\delta[/tex](x)


Homework Equations


In the previous portion I was able to prove
x [tex]\frac{d}{dx}[/tex] ([tex]\delta[/tex](x))= -[tex]\delta[/tex](x)


The Attempt at a Solution


I thought the problem was a heavyside problem but upon closer inspection, I noticed that on the heavyside step function it is 1 when x [tex]\geq[/tex] 0.

So how do I resolve this? Is there a way to change it so that it looks like a heavyside function, because that makes the problem much more convenient.:smile:
 
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  • #2
Hi CasualDays! :smile:

(have a theta: θ and a delta: δ :smile:)

Hint: what is 1 - θ(x)? :wink:
 
  • #3
tiny-tim said:
Hi CasualDays! :smile:

(have a theta: θ and a delta: δ :smile:)

Hint: what is 1 - θ(x)? :wink:

It's always the easy solutions that allude me..:biggrin:
 

Related to Exploring the Relationship between the Step Function and Dirac Delta Function

1. What is the Dirac Delta function?

The Dirac Delta function, denoted by δ(x), is a mathematical function that is defined to be zero everywhere except at x = 0, where it is infinite. It is often used in physics and engineering to describe point-like particles or impulses.

2. How is the derivative of the Dirac Delta function defined?

The derivative of the Dirac Delta function is defined using the concept of the generalized function. It is defined as the limit of a sequence of functions that approach the Dirac Delta function, and it is equal to zero everywhere except at x = 0, where it is undefined.

3. Why is the derivative of the Dirac Delta function undefined at x = 0?

The derivative of the Dirac Delta function is undefined at x = 0 because the function itself is not continuous at this point. The Dirac Delta function has an infinite discontinuity at x = 0, which makes it impossible to define a derivative at this point.

4. What is the physical interpretation of the derivative of the Dirac Delta function?

The physical interpretation of the derivative of the Dirac Delta function is that it represents an infinitely short and strong impulse. It can be thought of as a spike or a point-like particle that has an instantaneous effect on a physical system.

5. How is the derivative of the Dirac Delta function used in applications?

The derivative of the Dirac Delta function has many applications in physics and engineering. It is commonly used to model point-like forces or impulses in mechanics and to describe point charges in electromagnetism. It is also used in signal processing to represent sudden changes in a signal or to filter out unwanted high-frequency components.

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