Function: hgmalpha
Section: hypergeometric_motives
C-Name: hgmalpha
Prototype: G
Help: hgmalpha(H): returns the alpha and beta parameters of the hypergeometric
 motive template H.
Doc:  returns the alpha and beta parameters of the hypergeometric motive
 template $H$.
 \bprog
 ? H = hgminit([5]); \\ template given by cyclotomic parameters
 ? hgmalpha(H)
 %2 = [[1/5, 2/5, 3/5, 4/5], [0, 0, 0, 0]]
 @eprog
