Function fftn_simd 

pub fn fftn_simd<T>(
    x: &[T],
    shape: Option<&[usize]>,
    axes: Option<&[usize]>,
    norm: Option<&str>,
) -> FFTResult<ArrayD<Complex64>>
where
    T: NumCast + Copy + Debug + 'static,

SIMD-accelerated N-dimensional FFT