7 earlier thoughts
You can do a discrete Fourier transform in just one short line of J:
dft=: +/ .* ^@o.@(0j2&% * (*/ -)@i.)@#
Courtesy of this post by Andrey Paramonov which I indirectly found via a link from Dave's recently TIL post on the jlang hashtag.
2 later thoughts
ctrl + enter
alt + enter