proposition: Lemma find_pivotP m n (A : 'M[E]_(m.+1, n.+1)) : pick_spec [pred ij | A ij.1 ij.2 != 0] (find_pivot A).
proof: Proof. exact: pickP. Qed.
imports: mathcomp(all_ssreflect) mathcomp(all_algebra) mathcomp(all_fingroup) mathcomp(all_real_closed) CoqEAL(binetcauchy ssrcomplements mxstructure minor) CoqEAL(smith dvdring polydvd) CoqEAL(similar perm_eq_image)