Transforming piecewise continuous functions

In summary, the integrals in Laplace transforms and Fourier series can be added because the integration operator is linear, and continuity is not necessary for Laplace transforms. The function must meet certain conditions related to integrability, but continuity is not one of them.
  • #1
djeitnstine
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I was just reflecting upon my math courses and wondered why can we transform any piecewise continuous functions by using transforms such as laplace transforms or converting to Fourier series by simply adding the required integrals on the respective bounds?
 
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  • #2
djeitnstine said:
I was just reflecting upon my math courses and wondered why can we transform any piecewise continuous functions by using transforms such as laplace transforms or converting to Fourier series by simply adding the required integrals on the respective bounds?

Your statement is a little confusing. In any case, continuity is not necessary for Laplace transforms, which are integrals from 0 to oo, while Fourier series are obtained by integrals over a finite interval. The function has to meet certain conditions related to integrability, but continuity is not one of them.
 
  • #3
Yes but why can the integrals simply be added in both cases?

Example:

[tex]f(t)= \left\{^{5, t<1}_{sin(t), t>1}[/tex] So the laplace transform of this would be

[tex]L\left\{ f(t) \right\} = \int_0^1 5e^{-st}dt + \int_1^{\infty} sin(t)e^{-st}dt[/tex]

Why can they just be added?
 
Last edited:
  • #4
djeitnstine said:
Yes but why can the integrals simply be added in both cases?

Example:

[tex]f(t)= \left\{^{5, t<1}_{sin(t), t>1}[/tex] So the laplace transform of this would be

[tex]L\left\{ f(t) \right\} = \int_0^1 5e^{-st}dt + \int_1^{\infty} sin(t)e^{-st}dt[/tex]

Why can they just be added?

Well.

[tex]L\left\{ f(t) \right\} = \int_0^{\infty} e^{-st} f(t) dt [/tex]

[tex]L\left\{ f(t) \right\} = \int_0^1 f(t)e^{-st}dt + \int_1^{\infty} f(t)e^{-st}dt[/tex]

[because the integration operator is LINEAR]

which then becomes

[tex]L\left\{ f(t) \right\} = \int_0^1 5e^{-st}dt + \int_1^{\infty} sin(t)e^{-st}dt[/tex]
 
  • #5
Hmm. I should be hitting myself in the head.
 

1. What is a piecewise continuous function?

A piecewise continuous function is a mathematical function that is defined by different equations on different intervals of its domain. This means that the function has different rules for different parts of its input values, but it is still continuous overall.

2. How do you transform a piecewise continuous function?

To transform a piecewise continuous function, you can apply different transformations such as translations, reflections, or stretches to each piece of the function. These transformations will affect the shape and position of the function, but each piece will still be continuous.

3. What are the advantages of using piecewise continuous functions?

Piecewise continuous functions are useful for modeling real-world situations where different rules apply in different scenarios. They allow for more flexibility and accuracy in representing complex relationships between variables.

4. How do you graph a piecewise continuous function?

To graph a piecewise continuous function, you can first graph each individual piece of the function on its respective interval. Then, you can connect the pieces together to create a continuous graph. It is also helpful to label the points of intersection between the different pieces.

5. What are some common applications of piecewise continuous functions?

Piecewise continuous functions are commonly used in fields such as physics, engineering, and economics to model situations where different rules apply in different scenarios. They can also be used in computer programming and data analysis to represent complex relationships between variables.

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