快速傅里叶变换：史上最巧妙的算法

Reducible's visual walkthrough of the Fast Fourier Transform, motivated by polynomial multiplication. It shows how the FFT's key ideas can be discovered by asking the right questions.

Why HN likes it: HN repeatedly calls it a fantastic explanation that made FFT click, with some rewatching it periodically.

“It derives the FFT algorithm from polynomial multiplication and it’s fantastic . I rewatch it every 6 months or so.”