proposition: Lemma ger0_Im (x : R[i]) : 0 <= x -> Im x = 0.
proof: Proof. by move: x=> [a b] /=; simpc => /andP [/eqP]. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg ssrint div ssrnum rat poly closed_field) mathcomp(polyrcf matrix mxalgebra tuple mxpoly zmodp binomial realalg) mathcomp(mxpoly)