where, in Equation , the secular approximation part of equation 2 for large B 0 has been assumed (see Ref. for a general discussion). The distant dipolar field is a nonlocal quantity, making its computation difficult. However, as has been recognized long ago, Equation 11 has the form of a convolution in the real space, so that its Fourier transform with respect to the spatial coordinates is local quantity, which is expressed as a product in the reciprocal space. In terms of the three-dimensional Fourier transforms