Decompose Even & Odd parts of a function?

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Discussion Overview

The discussion revolves around the decomposition of functions into their even and odd parts, specifically focusing on examples such as the complex function f(x) = e^ix, the Heaviside step function, and polynomial functions like f(x) = x^2 and f(x) = x^3. Participants explore the definitions and implications of even and odd functions in various contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the meaningfulness of decomposing complex-valued functions into even and odd parts.
  • Another participant presents a general formula for decomposing any function into even and odd components.
  • A participant suggests that for the Heaviside step function, the even part might equal the odd part, prompting a challenge from another participant.
  • Clarifications are made regarding the even and odd parts of the Heaviside function, with specific values provided for positive and negative x.
  • Further exploration is conducted with polynomial functions, where participants analyze the even and odd parts of f(x) = x^2 and f(x) = x^3.
  • One participant discusses the absolute value function, providing a breakdown of its even and odd components for positive and negative x.
  • Participants express uncertainty about the correct use of LaTeX formatting in the discussion.

Areas of Agreement / Disagreement

There is no consensus on the meaningfulness of decomposing complex-valued functions into even and odd parts, and participants present differing views on the even and odd components of the Heaviside function and the absolute value function.

Contextual Notes

Participants rely on specific definitions and properties of even and odd functions, but there are unresolved assumptions regarding the applicability of these definitions to complex functions and piecewise functions like the Heaviside function.

radiator
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How would you decompose a given function to its even and odd parts? let's say you have f(x)=e^ix, and would like to know the even and odd parts of it? how do you proceed?

Thank you
 
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It is not particularly meaningful to decompose complex-valued functions as "even" or "odd".

however, any function f(x), can be written as the sum of two functions:
f(x)=(f(x)+f(-x))/2+(f(x)-f(-x))/2
 
Thanks arildno,
I suppose if I have a step function, the even part will be equal to odd part?
i.e. f(x) = (H(x) + 0)/2 + (H(x) - 0 )/2
since H(x) = 0 for x<0
 
Not really.

For positive x, H_even(x)=1/2, and of course, for negative x, we have H_even(x)=1/2

The odd part of the Heavyside function is, for x>0, H_odd(x)=1/2, whereas for x<0, H_odd(x)=-1/2.
 
I get it, but just to further understand more

suppose again I have f(x) = x^2 , which means the f_e(x) = x^2 and f_o(x) = 0, similarly f(x) = x^3 gives f_e(x) = 0 and f_o(x) = x^3 which is graphically a reflection around the y-axis and the origin, respectively.

but for absolute x it would be f_e(x) = (x+x)/2 = x for x>0 and f_e(x) = (x+(-(-x)))/2 = x
f_o = (x-x)/2 = 0 for x>0 and f_o(x) = (x-(-(-x)))/2 = 0 for x<0 , is this right ?

btw I though latex works here but I can't find the correct code, test: <latex> $\beta$ <\latex>
 
Now, for x>0, we have:

|x|=(|x|+|-x|)/2+(|x|-|-x|)/2, that is =(x+-(-x))/2+(x--(-x))/2=x+0, as it ought to be

For x<0, we have:
|x|=(|x|+|-x|)/2+(|x|-|-x|)/2=(-x+-x)/2+(-x--x)/2=-x+0, as it ought to be.

Thus, f_(e)(x) equals the absolute value function itself. Also as it ought to be, I may add.
 
Thanks very much arildno :)
 

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