How evaluate this f(x)=x^2+(1)/(1+2x^4) with fourier tranform

ormaybesaladqh

ormaybesaladqh

Answered question

2022-10-23

How evaluate this f ( x ) = x 2 + 1 1 + 2 x 4 with fourier tranform

Answer & Explanation

ehedem26

ehedem26

Beginner2022-10-24Added 13 answers

The Fourier transform of f(x) doesn't exist in the usual sense, but since f can be viewed as a tempered distribution, we can interpret the Fourier transform in that setting. (I'm using the normalization f ^ ( ω ) = e i ω t f ( t ) d t. If you're using something else, the answer is a little different.)
First of all, Fourier transform of 1 is 2 π δ ( ω ). Hence
t F 2 π i δ ( ω ) t 2 F 2 π i 2 δ ( ω ) = 2 π δ ( ω ) .
The second term is less problematic, and exists in the usual sense. It is a standard exercise in residue calculus to compute the Fourier transform of 1 1 + 2 x 4 . The result (and especially all the intermediate steps) are very messy though. I get:
f ^ ( ω ) = 2 π δ ( ω ) + { π q e q ω ( cos q ω sin q ω ) , ω < 0 π q e q ω ( sin q ω cos q ω ) , ω 0
where q = 2 1 / 4 / 2

Do you have a similar question?

Recalculate according to your conditions!

New Questions in Differential Equations

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?