proposition: Lemma r_of_p0 p : p != 0%:pr -> [r_of p, 0%:pr] = 1%:pr.
proof: Proof. by move=> p0; apply val_inj; rewrite /= r_of_pqE s_of_p0 divff. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) mathcomp(reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(lra ring Rstruct)