proposition: Lemma sqrtr0 : sqrt 0 = 0 :> R.
proof: Proof. by move: (sqrtr_sqr 0); rewrite exprS mul0r => ->; rewrite normr0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)