来自官方MATLAB文档:

FFT函数(fft，fft2，fftn，ifft，ifft2，ifftn)基于名为 FFTW a>.

要在N为复合值(即N = N ₁ N ₂ )时计算N点DFT，FFTW库使用 Cooley-Tukey算法，该算法首先计算N ₁ 大小为N ₂ 的变换，然后计算大小为N ₁ 的N ₂ 个变换.

To compute an N-point DFT when N is composite (that is, when N = N₁N₂), the FFTW library decomposes the problem using the Cooley-Tukey algorithm, which first computes N₁ transforms of size N₂, and then computes N₂ transforms of size N₁.

当N是质数时，FFTW库首先使用

When N is a prime number, the FFTW library first decomposes an N-point problem into three (N – 1)-point problems using Rader's algorithm. It then uses the Cooley-Tukey decomposition described above to compute the (N – 1)-point DFTs.

我不确定Apple的Accelerate Framework如何计算此类FFT，但我在这里偏爱MATLAB来产生正确的结果.

I'm not sure how Apple's Accelerate Framework computes such FFTs, but I'm favouring MATLAB here to produce correct results.