FFT converts vector to [[Complex]]

[jcollard]

This has awful run time implications:

unm-hip/Data/Image/Complex.hs

Lines 306 to 311 in 95272db

	fft' :: FFT a -> Int -> Int -> Vector a -> Vector a
	fft' range rows cols orig = if check then fromRows rows' else err where
	check = and . map isPowerOfTwo $ [rows, cols]
	err = error "FFT can only be applied to images with dimensions 2^k x 2^j where k and j are integers."
	(fromColumns -> cols') = map (fftc range rows cols 0 (rows-1) orig) [0..cols-1] -- FFT on each col
	rows' = map (fftr range cols 0 (cols-1) cols') [0..rows-1] -- FFT on each row