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scipy.fftpack.fftn

scipy.fftpack.fftn(x, shape=None, axes=None, overwrite_x=0)

Return multidimensional discrete Fourier transform.

The returned array contains:

y[j_1,..,j_d] = sum[k_1=0..n_1-1, ..., k_d=0..n_d-1]
   x[k_1,..,k_d] * prod[i=1..d] exp(-sqrt(-1)*2*pi/n_i * j_i * k_i)

where d = len(x.shape) and n = x.shape. Note that y[..., -j_i, ...] = y[..., n_i-j_i, ...].conjugate().

Parameters :

x : array_like

The (n-dimensional) array to transform.

shape : tuple of ints, optional

The shape of the result. If both shape and axes (see below) are None, shape is x.shape; if shape is None but axes is not None, then shape is scipy.take(x.shape, axes, axis=0). If shape[i] > x.shape[i], the i-th dimension is padded with zeros. If shape[i] < x.shape[i], the i-th dimension is truncated to length shape[i].

axes : array_like of ints, optional

The axes of x (y if shape is not None) along which the transform is applied.

overwrite_x : bool, optional

If True, the contents of x can be destroyed. Default is False.

Returns :

y : complex-valued n-dimensional numpy array

The (n-dimensional) DFT of the input array.

See also

ifftn

Examples

>>> y = (-np.arange(16), 8 - np.arange(16), np.arange(16))
>>> np.allclose(y, fftn(ifftn(y)))
True