proposition: Lemma real_eqr_norm2 x y : x \is real -> y \is real -> (`|x| == `|y|) = (x == y) || (x == -y).
proof: Proof. move=> Rx Ry; rewrite real_eqr_norml // normrE andbT. by case: real_le0P; rewrite // opprK orbC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)