Talk:Discrete Fourier transform

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Are the equations for the dft and inverse dft swapped??

Latest comment: 2 years ago1 comment1 person in discussion

I have been working through the dft by hand, I have checked my math multiple times and have used wolfram alpha to provide more checking, but for the input x={1,2,3,4}

I keep getting X={10, -2+2i, -2, -2-2i}

and wolfram is giving me fft{1,2,3,4} = {5, -1-i, -1,-1+i}, but the ifft{1,2,3,4} = {5, -1+i, -1, -1-i}

This is only one half what I calculated by hand and so this is what makes me think the dft and inverse dft are swapped.

Also there might be something about dividing the result by 2, to be explored. 209.159.200.170 (talk) 20:33, 3 December 2022 (UTC)Reply

Motivation

Latest comment: 2 years ago1 comment1 person in discussion

Please add a section explaining what this algorithm accomplishes. I passed an entire undergrad course on this topic, and still don't understand what the purpose of the transform is. Please help -- I'm not the only one! KatyKathinka (talk) 00:02, 23 April 2023 (UTC)Reply

Link to subsection in Representation theory of finite groups no longer exists

Latest comment: 1 year ago1 comment1 person in discussion

"Further information: Representation theory of finite groups § Discrete Fourier transform" is missing 2A0C:5BC0:40:10C0:DE4A:3EFF:FE6D:C214 (talk) 14:57, 4 March 2024 (UTC)Reply

Aren't the Plancherel and Parseval theorem mistaken for each other?

Latest comment: 5 months ago1 comment1 person in discussion

In the "properties" section, the "The Plancherel theorem and Parseval's theorem" subsection asserts that Plancherel is a specific case of Parseval. But the respective Wikipedia pages of the two theorems (https://en.wikipedia.org/wiki/Plancherel_theorem and https://en.wikipedia.org/wiki/Parseval%27s_theorem) say the contrary... 2A01:CB08:46C:8200:E099:9A9:605B:52AF (talk) 05:58, 16 March 2025 (UTC)Reply