[Wien] About "Bolz Trap"

[Oleg Artamonov]

Dear Georg Madsen,

I would like to use the scheme of the interpolation from the  "Bolz 
Trap" package to get some intermediate derivations.
How is it possible to extract (if it is possible) the group velocity 
(the states density) and the effective mass?

Thanks in advance,
                            Oleg Artamonov.