  While galaxy cluster catalogs were compiled many decades ago, other
structural elements of cosmic web are detected at definite level only in the
newest works. For example, extragalactic filaments were described by velocity
field and SDSS galaxy distribution during the last years. Large-scale structure
of the Universe could be also mapped in the future using ATHENA observations in
X-rays and SKA in radio band. Until detailed observations are not available for
the most volume of Universe, some integral statistical parameters can be used
for its description. Such methods as galaxy correlation function, power
spectrum, statistical moments and peak statistics are commonly used with this
aim. The parameters of power spectrum and other statistics are important for
constraining the models of dark matter, dark energy, inflation and brane
cosmology. In the present work we describe the growth of large-scale density
fluctuations in one- and three-dimensional case with Fourier harmonics of
hydrodynamical parameters. In result we get power-law relation for the matter
power spectrum.
