Trying to invert an expression

  • Thread starter Morberticus
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In summary, the conversation is about a transform expressed as n(k) = ∫cos(x-y)f(x,y)dxdy and whether there is a name for it. The person is trying to invert it to obtain f(x,y) but is not used to the 2D integral on the right-hand side. They tried to turn it into a Fourier transform but got stuck. It is mentioned that the correct expression is n(k) = ∫cos(k(x-y))f(x,y)dxdy and it is suggested that it is analogous to the cosine transform. The person is directed to a resource that may be helpful and it is noted that it is possible to use the inverse Fourier transform.
  • #1
Morberticus
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I've come across an expression that looks like

n(k) = ∫cos(x-y)f(x,y)dxdy

Is there a name for this transform? I would like to invert it to obtain f(x,y) but I'm not used to the 2D integral on the RHS. I tried to turn it into a Fourier transform:

n(k) = 1/2 ( ∫eixe-iyf(x,y)dxdy + ∫e-ixeiyf(x,y)dxdy)

but got stuck. Any help would be appreciated.

Thanks
 
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  • #2
Hi, there is something of strange, where is ##k## in the integral?, you say ##n(k)## but in the right side I don't see ##k##, and what is the domain of integration ?
 
  • #3
You are right! Sorry, I forgot about the k when writing down the expression(s). The correct expression is

n(k) = ∫ cos( k(x-y) ) f(x,y) dxdy

Thanks
 
  • #4
I think your transform is analogous to the ''cosine transform'', I hope you can find something useful here

http://dsp-book.narod.ru/TAH/ch03.pdf

but I think (as you wrote...) it is possible to use the inverse Fourier transform...
 

FAQ: Trying to invert an expression

1. Can any expression be inverted?

Yes, any expression can be inverted as long as it follows the rules of algebra and does not contain any undefined values.

2. What is the purpose of inverting an expression?

Inverting an expression allows us to solve for a specific variable or unknown value. It can also help simplify complex equations.

3. How do you invert an expression?

The first step is to isolate the variable that you want to solve for. Then, you can use algebraic operations such as multiplication, division, addition, and subtraction to rearrange the equation and solve for the variable.

4. Are there any limitations to inverting an expression?

There are certain expressions that cannot be inverted, such as ones with multiple variables or ones that contain trigonometric functions. In these cases, we can still simplify the expression, but we cannot solve for a specific variable.

5. Can inverting an expression lead to incorrect solutions?

Yes, inverting an expression can lead to incorrect solutions if the algebraic steps are not performed correctly. It is important to check the solution by plugging it back into the original expression to ensure it is valid.

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