Fact unitGI_out : {in [predC unitGI], invGI =1 id}.
Definition GI_comUnitRingMixin :=
ComUnitRingMixin mulGIr unitGIP unitGI_out.
Canonical GI_unitRingType := UnitRingType GI GI_comUnitRingMixin.
Canonical GI_comUnitRingType := [comUnitRingType of GI].

Lemma normGIE (x : GI) : ('N(x) = truncC (`|'Re (val x)|) ^ 2 + truncC (`|'Im (val x)|) ^ 2)%N.