proposition: Lemma signr_scalq x : (scalq x < 0) = (x.2 < 0).
proof: Proof. by rewrite -!sgr_cp0 sgr_scalq. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order ssralg countalg div ssrnum) mathcomp(ssrint prime archimedean)