Some new GP features
lfundual
Ld=lfundual(L) returns the dual L-function of L, such that
the usual functional equation holds:
ΛL(s) = ΛLd (k − s)
where  is the root number.
? L = lfunqf(matdiagonal([1,2,3,4]));
? Ld = lfundual(L);
? eps = lfunrootres(L)[3]
%45 = 2.4494897427831780981972840747058913920
? lfunlambda(L,Pi)/lfunlambda(Ld,2-Pi)
%46 = 2.4494897427831780981972840747058913920