  It is commonly assumed that a lattice of skyrmions, emerging in
two-dimensional non-centrosymmetric magnets in external magnetic fields, can be
represented as a sum of three magnetic helices. In order to test this
assumption we compare two approaches to a description of regular skyrmion
structure. We construct (i) a lattice of Belavin-Polyakov-like skyrmions within
the stereographic projection method, and (ii) a deformed triple helix defined
with the use of elliptic functions. The estimates for the energy density and
magnetic profiles show that these two ansatzes are nearly identical at zero
temperature for intermediate magnetic fields. However at higher magnetic
fields, near the transition to topologically trivial uniform phase, the
stereographic projection method is preferable, particularly, for the
description of disordered skyrmion liquid phase. We suggest to explore the
intensities of the secondary Bragg peaks to obtain the additional information
about the magnetic profile of individual skyrmions. We estimate these
intensities to be several percents of the main Bragg peak at high magnetic
fields.
