D.7.5.8 EGCDMain

Procedure from library zeroset.lib (see zeroset_lib).

Purpose:

compute the polynomial gcd of f and g over Q(a)[x]

Return:

poly

Assume:

basering = Q[x,a] and ideal mpoly is defined (it might be 0), this represents the ring Q(a)[x] together with its minimal polynomial.