Function: qfbnupow
Section: number_theoretical
C-Name: nupow
Prototype: GG
Help: qfbnupow(x,n): n-th power of primitive positive definite quadratic
 form x using nucomp and nudupl.
Doc: $n$-th power of the primitive positive definite
 binary quadratic form $x$ using \idx{Shanks}'s NUCOMP and NUDUPL algorithms
 (see \kbd{qfbnucomp}, in particular the final warning).