WyckoffPositionsQClass( G, S )
For space groups with larger point groups, most of the time in the
computation of Wyckoff positions (see Wyckoff Positions) is spent
computing the subgroup lattice of the point group. If Wyckoff positions
are needed for several space groups which are in the same Q class, and
therefore have isomorphic point groups, one can avoid recomputing the
same subgroup lattice for each of them as follows. For the computation
of the Wyckoff positions of the first space group S one uses a call to
WyckoffPositions. For the remaining space groups, S is then passed
as a second argument to WyckoffPositionsQClass( G, S ), which uses
some of the results already obtained for S.
GAP 3.4.4