Talk:Discrete Fourier transform

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

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)

Motivation

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)

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

"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)

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

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)

Recent YouTube video

I came across a YouTube video recently which appears to be gaining some traction, discussing the topic of mathematics articles on Wikipedia. It begins with some criticism of this article, which editors may find helpful in improving our coverage of the topic. Hence, I'm posting it here for anyone who is interested. [1] Golem08 (talk) 23:52, 6 November 2025 (UTC)

The video is basically a 14 minute digression. It starts off with complaining that Wikipedia is bad at teaching math, only to recognize that Wikpedia is WP:NOTTEXTBOOK. Then he goes on that Wikipedia is also bad as a reference and that the cited references are written by people who are also bad at teaching math. Completely ignoring the fact that publications in mathematical journals are not written to "teach maths". It's like looking up sheet music by Bach, only to complain that it doesn't teach you to play it yourself and that musical notation is not intuitive enough.

The last 10 minutes of the video are about how to test random number generators, which has nothing to do with wikipedia.

That being said, I do think the DFT article is a bit messy. I feel it has been written with an "application focus" in mind, taking very little time to talk about the underlying mathematical context. It may be beneficial to talk a bit more about it's relation to the Fourier transform and/or Fourier series.

Kind regards, Roffaduft (talk) 09:03, 7 November 2025 (UTC)