NEDAS.utils.fft_lib module

NEDAS.utils.fft_lib.fft2(f: ndarray) → ndarray

2D FFT implemented by pyFFTW. If pyFFTW is not available, will switch to np.fft.fft2

Parameters:

f (np.ndarray) – Input field, of shape (…, ny, nx), of float32 type, the last two dimensions will be transformed by the 2D FFT.

Returns:

Output field in spectral space, of complex64 type.

Return type:

np.ndarray

NEDAS.utils.fft_lib.ifft2(fh: ndarray) → ndarray

Inverse 2D FFT implemented by pyFFTW. If pyFFTW is not available, will switch to np.fft.ifft2

Parameters:

fh (np.ndarray) – Input field, of shape (…, nky, nkx), of complex64 type, the last two dimensions will be inverse transformed by 2D FFT.

Returns:

Output field in physical space, of float32 type.

Return type:

np.ndarray

NEDAS.utils.fft_lib.fftwn(n)

Wavenumber sequence corresponding to the FFT output in 1 dimension.

Parameters:

n (int) – The size of the dimension

Returns:

The sequence of wavenumber (0,1,2,…-2,-1) for this dimension

Return type:

np.ndarray

NEDAS.utils.fft_lib.get_wn(fld)

Generates a meshgrid of wavenumbers corresponding to the input field dimensions.

Parameters:

fld (np.ndarray) – Input field, the last two dimensions are the horizontal directions (ny, nx)

Returns:

Wavenumbers corresponding to the input fields dimensions, relative to the domain size (nx or ny, whichever is larger).

Return type:

np.ndarray