Index of a groupsubgroup pair

The program INDEX calculates the index of a group subgroup pair. The index can be calculated in two different ways given:
 Option A
 The space group ITA numbers.
 The number of formula units per conventional unit cell.
 Option B
 The space group ITA numbers.
 The lattice parameters.
The number of formula units per conventional unit cell Z_{c} is simply related to the number Z of formula units per primitive unit cell via the socalled centring factor f, Z=Z_{c}/f, with f=1 for primitive lattices, 2 for I, C, B, A centred, 3 for Rcentred and 4 for Fcentred lattice.


