proposition: Theorem SF2B_B2SF : forall x H, SF2B (B2SF x) H = x.
proof: Proof. intros [sx|sx| |sx mx ex Hx] H ; try easy. apply f_equal, eqbool_irrelevance. Qed.
imports: Coq(ZArith Reals Psatz SpecFloat) Core Round Bracket Operations Div Sqrt Relative