Tracing through the execution znlog does
h = Rg_to_Fp(Mod(148670581, 268890659), 10);
(forgive my conflation of C and GP for the moment) which sets h = 0 and hence
p_log(0, Mod(10, 268890659), 268890658, 10)
is undefined. But really the Rg_to_Fp call is invalid since 10 does not divide 268890659.
I don't have a good idea of what the code is supposed to be doing at this point...
Charles Greathouse
Analyst/Programmer
Case Western Reserve University