  The Fourier transformation is an effective and efficient operation of
Gaussianization at the one-point level. Using a set of N-body simulation data,
we verified that the one-point distribution functions of the dark matter
momentum divergence and density fields closely follow complex Gaussian
distributions. The one-point distribution function of the quotient of two
complex Gaussian variables is introduced and studied. Statistical theories are
then applied to model one-point statistics about the growth of individual
Fourier mode of the dark matter density field, which can be obtained by the
ratio of two Fourier transformed cosmic fields. Our simulation results proved
that the models based on the Gaussian approximation are impressively accurate,
and our analysis revealed many interesting aspects about the growth of dark
matter's density fluctuation in Fourier space.
