Fast Fourier Transforms (FFTs) : this module implements some basic FFT operations. Most of them are similar to the same funcitons in Matlab, and you will find it very easy to use in case you are familiar with Matlab.
type rmat = Owl_dense_matrix_d.mattype cmat = Owl_dense_matrix_z.matfft x performs an FFT operation on matrix x. If x has more than one row, then one FFT operation will be performed on each of them. The input is a real dense matrix, and the returned result is a complex dense matrix.
fft_complex x is similar to fft x but is performed on complex matrices.
ifft x performs the inverse operation of FFT on x. Note the input x is a complex matrix, both the output from fft x and fft_complex x can be used as the input of ifft.
fft2_complex x is similar to fft2 x but is performed on complex matrices.
ifft2 x performs the inverse operation of FFT on x, i.e., the inverse function of both fft2 and fft2_complex.
fftshift x shifts the zero frequency component in the middle. This is especially useful when plotting the figures.