AddTranslationsCrystGroup( G, basis )
Since TranslationsCrystGroup (see TranslationsCrystGroup) needs a
presentation of the point group, the computation of G.translations can
be rather time consuming. If a basis of the translation lattice is known,
AddTranslationsCrystGroup can be used to add this knowledge to a
CrystGroup. If G.translations is already known, its value is kept
without further notice. It is the responsibility of the user that the
basis handed over to AddTranslationsCrystGroup is a correct basis of
the translation lattice. In case of doubt, the function
CheckTranslations (see CheckTranslations) can be used to check
whether the basis added was indeed correct.
Warning: The component G.translations must never be set by hand.
The functions TranslationsCrystGroup and AddTranslationsCrystGroups
have important (and wanted) side effects.
GAP 3.4.4