Function: thueinit
Section: polynomials
C-Name: thueinit
Prototype: GD0,L,p
Help: thueinit(P,{flag=0}): initialize the tnf corresponding to P, that will
 be used to solve Thue equations P(x,y) = some-integer. If flag is non-zero,
 certify the result unconditionaly. Otherwise, assume GRH (much faster of
 course).
Doc: initializes the \var{tnf} corresponding to $P$, a univariate polynomial
 with integer coefficients. The result is meant to be used in conjunction with
 \tet{thue} to solve Thue equations $P(X / Y)Y^{\deg P} = a$, where $a$ is an
 integer.

 If $\fl$ is non-zero, certify results unconditionally. Otherwise, assume
 \idx{GRH}, this being much faster of course. In the latter case, the result
 may still be unconditionally correct, see \tet{thue}. For instance in most
 cases where $P$ is reducible (not a pure power of an irreducible), \emph{or}
 conditional computed class groups are trivial \emph{or} the right hand side
 is $\pm1$, then results are always unconditional.
