Function: qfbnucomp
Section: number_theoretical
C-Name: nucomp
Prototype: GGG
Help: qfbnucomp(x,y,L): composite of primitive positive definite quadratic
 forms x and y using nucomp and nudupl, where L=[|D/4|^(1/4)] is precomputed.
Doc: \idx{composition} of the primitive positive
 definite binary quadratic forms $x$ and $y$ (type \typ{QFI}) using the NUCOMP
 and NUDUPL algorithms of \idx{Shanks}, \`a la Atkin. $L$ is any positive
 constant, but for optimal speed, one should take $L=|D|^{1/4}$, where $D$ is
 the common discriminant of $x$ and $y$. When $x$ and $y$ do not have the same
 discriminant, the result is undefined.

 The current implementation is straightforward and in general \emph{slower}
 than the generic routine (since the latter takes advantage of asymptotically
 fast operations and careful optimizations).

Variant: Also available is \fun{GEN}{nudupl}{GEN x, GEN L} when $x=y$.
