proposition: Lemma pow2_Rle_inv a b : 0 <= a -> 0 <= b -> a ^ 2 <= b ^ 2 -> a <= b.
proof: Proof. move=> Ha Hb H. apply sqrt_le_1 in H; try exact: pow_even_ge0. by rewrite /= !mulR1 !sqrt_square in H. Qed.
imports: mathcomp(all_ssreflect) mathcomp(all_algebra vector reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(Rstruct) ssrR realType_ext Reals Lra mathcomp(lra)